HK1100771B - Embossed release paper for production of synthetic leather, support thereof, synthetic leather utilizing the release paper and process for producing the same - Google Patents

Description

Embossed release paper for producing synthetic leather, support for the same, synthetic leather using the same, and method for producing the same

Technical Field

The present invention relates to an embossed release paper for producing synthetic leather, a support for the same, synthetic leather using the release paper, and a method for producing the same. More specifically, the present invention relates to an embossed release paper using an ionizing radiation curable coating material having a specific composition.

Background

Conventionally, embossed release paper has been used as a process release paper for synthetic leather. Further, as a raw material of synthetic leather, polyurethane (hereinafter abbreviated as PU), vinyl chloride (hereinafter abbreviated as PVC), a combination of PU and PVC, and the like are known.

Examples of the method for producing the PU leather include: coating a PU resin for a skin layer in a paste form on a release paper, drying and curing the resin at a temperature of 90 to 140 ℃, bonding the cured resin to a base fabric with a two-component curing type PU adhesive, reacting the resultant product in a curing chamber at a temperature of 40 to 70 ℃ for 2 to 3 days, and then releasing the release paper to produce a PU leather. These PU resins are generally of the organic solvent-soluble type, but recently, from the viewpoint of environmental problems, there are also aqueous types. In this case, the drying may be performed at a high temperature of 150 to 180 ℃.

In addition, as a method for producing PVC leather, there is a method in which a PVC sol is applied to a release paper, heated to 200 to 250 ℃ to gel the PVC sol, a PVC foam layer is formed and attached to a base fabric, and thereafter the release paper is peeled off to produce PVC leather.

Further, as a method for producing leather (also referred to as semi-synthetic leather) in which PU and PVC are combined, there is a method in which a paste-like PU resin for a skin-like layer is applied to a release paper, dried and cured, then a PVC foam layer is bonded to a base fabric, and thereafter the release paper is peeled.

Further, split leather (split leather) obtained by bonding these synthetic leathers to natural leather is also known.

In the production of PVC leather and semi-synthetic leather, a release paper coated with a silicone resin and embossed by embossing is generally used. However, since PVC has a relatively high film forming temperature, it has a disadvantage that it is poor in emboss formability and is liable to cause unevenness in gloss, and it is difficult to repeatedly use the release paper.

In contrast, in the production of PU leather, since the film forming temperature of PU is lower than that of PVC, a release paper is used in which a thermoplastic resin such as polypropylene and 4-methyl-1-pentene is extruded and coated, and embossed. The release paper for PU leather has excellent embossing formability, good releasability in the production of synthetic leather using two-component curing type PU, and excellent reusability. However, since the release paper is made of a thermoplastic resin, it has a problem that it is inferior in heat resistance and cannot be used for producing PVC leather.

From such a problem, the release paper extruded and coated with the thermoplastic resin is only partially used for PVC leather and semi-synthetic leather, and there is no release paper applicable to both PVC leather and PU leather.

In recent years, release papers using electron beam-curable resins such as isodecyl acrylate, which are excellent in emboss formability and heat resistance, have been used for both PU and PVC (Japanese patent publication No. 63-2780). The embossed release paper is obtained by the following method: an aluminum plate is embossed by applying an electron beam irradiation curable acrylate-based coating composition to the aluminum plate, pressing a paper web coated with a base containing a pigment and a binder onto the applied surface, irradiating the applied surface with an electron beam through the paper web layer to cure the coating film of the coating composition, and peeling the aluminum plate.

However, the above-mentioned release paper has an advantage of excellent emboss reproducibility, but the isocyanate curing agent used in the two-component curing type PU reacts with the electron beam curable resin on the surface of the release paper, and there is a disadvantage that the release paper is difficult to peel.

Further, since the strength of the release paper is deteriorated by electron beam irradiation and the heat resistance and durability of the release paper are deteriorated, there is a problem that the release paper is broken and cannot be used repeatedly when tension is applied to the release paper in a high-temperature drying oven in the production of synthetic leather.

In addition, since the electron beam curable resin is applied in a large amount, it is 40 to 150g/m²Therefore, the production cost of the release paper is also very high.

Further, there has been proposed a release paper using a resin containing, as a main component, a compound having an ethylenically unsaturated bond such as an epoxy acrylate resin which is cured by irradiation with ionizing radiation (Japanese patent publication No. Sho 64-10626). The embossed release paper is obtained by adopting the following method: the method for producing the paper comprises the steps of coating a coating material containing a compound having an ethylenically unsaturated bond as a main component on one surface of paper to form a cured coating layer, embossing the surface of the coating layer, and then irradiating the embossed coating layer with electron beams or ultraviolet rays to cure the coating layer.

However, as described above, it is not easy to peel off the two-component curing type PU material, and the practical use thereof has not yet been achieved at present.

In order to improve the above-mentioned problems, that is, the heat resistance of the release paper and the releasability when a two-component curing type PU is used, a method of using a silicone resin having an acryloyl group has also been proposed (Japanese patent application laid-open Nos. 5-269931 and 2001-62958). The embossed release paper disclosed in japanese unexamined patent publication No. 5-269931 is obtained by providing an ionizing radiation-curable resin layer on a support made of a paper having a clay coating layer, applying an acryl-containing silicone resin layer on the ionizing radiation-curable resin layer, embossing the surface of the resin layer, and then irradiating ultraviolet rays or electron beams to cure the ionizing radiation-curable resin layer and the silicone resin layer.

However, the resin raw material is not only expensive but also poor in releasability and processability, and thus has not been put to practical use.

Further, in the release paper of the type in which an uncured ionizing radiation-curable resin layer is provided on a support and the surface of the layer is subjected to embossing and then cured, as in the release paper with emboss disclosed in japanese patent publication No. 64-10626 and japanese patent application laid-open No. 5-269931, the surface morphology of the uncured ionizing radiation-curable resin layer before embossing is affected by the surface morphology of the uncured ionizing radiation-curable resin layer before embossing, and therefore, in order to obtain a release paper for synthetic leather having a glossy texture, the surface morphology of the uncured ionizing radiation-curable resin layer before embossing must be appropriate.

However, in the release paper using paper as a support, since the unevenness of the paper fiber also affects the surface of the uncured ionizing radiation curable resin layer, there is also a problem that it is difficult to obtain synthetic leather having a glossy texture. Further, when a tension is applied to the release paper in a high-temperature drying oven in the production of synthetic leather, the release paper having low heat resistance is used, and there is a problem that the release paper is broken and cannot be reused.

Disclosure of Invention

The present inventors have found that by using a specific ionizing radiation curable resin, an embossed release paper for synthetic leather production can be obtained which has excellent releasability even from a two-component curable PU adhesive and has excellent formability, heat resistance and durability.

The present inventors have also found that such release paper can be used for synthetic leathers such as PU, PVC, and semi-synthetic leathers.

The present inventors have also found that synthetic leather having a shape, heat resistance, durability and a glossy texture can be obtained by using a support made of a specific material as a release paper which can be used for any of synthetic leathers such as PU, PVC and semi-synthetic leathers.

Further, it has been found that by adjusting the content of the silicone compound in the release paper, excellent releasability is maintained even when the release paper is repeatedly used for the production of synthetic leather. The present invention is based on such findings.

Accordingly, a first object of the present invention is to provide an embossed release paper for synthetic leather production, which has shape-imparting properties, heat resistance and durability, is excellent in releasability even from a two-component curable PU adhesive, and can be used for synthetic leather such as PU, PVC and semi-synthetic leather, and a method for producing the same.

It is a second object of the present invention to provide an embossed release paper which is excellent in releasability and processability and which can produce synthetic leather at low cost even when the synthetic leather is produced by repeatedly using the release paper, and a method for producing the same.

It is a third object of the present invention to provide a support for an embossed release paper which is usable for synthetic leathers such as PU, PVC, and semi-synthetic leathers, has shape-imparting properties, heat resistance, and durability, and can give a glossy synthetic leather.

The embossed release paper for producing synthetic leather according to the first aspect of the present invention is an embossed release paper for producing synthetic leather, which comprises a paper having at least a support and an ionizing radiation curing film provided on the paper, and is obtained by embossing the curing film, wherein the ionizing radiation curing film is obtained by irradiating an ionizing radiation to cure a coating solution, the coating solution contains at least an ionizing radiation-curable composition having a softening point of 40 ℃ or higher, the curable composition comprises a reaction product of an isocyanate compound and a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, or an isocyanate compound, a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, and a (meth) acryloyl compound having no (meth) acryloyl group and being capable of reacting with an isocyanate group A reaction product of the compound.

In a second aspect of the present invention, there is provided a method for producing the embossed release paper for producing synthetic leather, comprising applying a coating liquid to a surface of a support so that the amount of the coating liquid applied after drying is 1 to 40g/m²A step of forming a coating film by evaporating and drying a solvent of the coating film; to the above-mentioned dried coating film, or the sameA step of embossing the support and the dried coating film; and a step of irradiating the coating film with ionizing radiation to form an ionizing radiation cured film, wherein the coating liquid contains at least an ionizing radiation curable composition having a softening point of 40 ℃ or higher, the curable composition containing a reaction product formed from an isocyanate compound and a (meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with the isocyanate compound, or a reaction product formed from an isocyanate compound, a (meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with the isocyanate compound, and a compound having no (meth) acryloyl group and capable of reacting with an isocyanate group, and the coating liquid is diluted with 10 to 1000 parts by weight of a solvent with respect to 100 parts by weight of solid components in the coating liquid.

A method for producing synthetic leather using an embossed release paper according to a third aspect of the present invention includes a step of applying a polyurethane resin composition to an ionizing radiation cured film subjected to the embossing process, and heating and drying the coating to form a skin-like layer; a step of bonding a base fabric to the surface layer with an adhesive to form a synthetic leather layer; and a step of peeling the release paper from the synthetic leather layer.

Further, a synthetic leather according to a fourth aspect of the present invention is a synthetic leather produced using the above-described embossed release paper, wherein a ratio of silicon derived from siloxane present on a release surface of the synthetic leather obtained by releasing the release paper is 20% or less.

Further, a fifth aspect of the present invention is a support for an embossed release paper for producing synthetic leather, comprising a base paper having a clay coating layer on one surface thereof, wherein the base paper has heat resistance such that a tensile strength measured by a measurement method based on JIS P8113 after being left at 230 ℃ for 3 minutes is maintained at least at 10kN/m in a longitudinal direction and a tear strength measured by a measurement method based on JIS P8116 after being left at 230 ℃ for 3 minutes is maintained at 500mN or more in both the longitudinal and transverse directions, and the clay coating layer is formed to have a smoothness of 100 seconds or more obtained by a measurement method based on JIS P8119, and surface irregularities due to pulp fibers of the base paper are absorbed.

According to the first to third aspects of the present invention, an embossed release paper for synthetic leather production can be realized which has shape-imparting properties, heat resistance, durability, and excellent releasability even with a two-component curable PU adhesive, and which can be used for synthetic leathers such as PU, PVC, and semi-synthetic leathers.

Further, according to the fourth aspect of the present invention, even when the synthetic leather is manufactured by repeatedly using the release paper, the embossed release paper for the synthetic leather can be obtained at low cost while being excellent in releasability and processability.

Further, according to the fifth aspect of the present invention, it is possible to realize a support for an embossed release paper which is usable for synthetic leathers such as PU, PVC, and semi-synthetic leathers, has shape-imparting properties, heat resistance, and durability, and can provide synthetic leathers having a glossy texture.

Drawings

Fig. 1 is a view showing an example of a process for producing an embossed release paper for producing synthetic leather according to the present invention.

Fig. 2 is a sectional view of a support of the embossed release paper for manufacturing synthetic leather according to the present invention.

Fig. 3 is a sectional view of the embossed release paper for manufacturing synthetic leather according to the present invention.

Detailed Description

(1) Embossed release paper for producing synthetic leather and method for producing same

The embossed release paper according to the present invention is embossed release paper for producing synthetic leather, which is provided with at least paper as a support and an ionizing radiation curing film provided on the paper, and which is embossed on the curing film, wherein the ionizing radiation curing film is formed by irradiating ionizing radiation to cure a coating liquid. First, the coating liquid will be described.

Coating liquid

The coating liquid used in the present invention is a composition containing an ionizing radiation curable composition having a softening point of 40 ℃ or higher, the curable composition containing a reaction product formed from an isocyanate compound and a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, or a reaction product formed from an isocyanate compound, a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, and a compound having no (meth) acryloyl group and being capable of reacting with an isocyanate group.

In the present specification, the term "(meth) acryloyl group" means an acryloyl group and/or a methacryloyl group, the term "(meth) acryloyl compound" means an acryloyl compound and/or a methacryloyl compound, (meth) acrylate "means acrylate and/or methacrylate, and the term" (meth) acrylic acid "means acrylic acid and/or methacrylic acid.

The isocyanate compound used in the present invention is a compound having at least 1 isocyanate group, and preferably a compound having 2 or more isocyanate groups. For example, aliphatic isocyanates such as phenyl isocyanate, ditolyl isocyanate, naphthyl isocyanate, hexamethylene diisocyanate, lysine methyl ester diisocyanate and 2, 4, 4-trimethylhexamethylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate and 4, 4 ' -methylenebis (cyclohexyl isocyanate), aromatic isocyanates such as tolylene diisocyanate, 4, 4 ' -diphenylmethane diisocyanate and naphthalene-1, 5 ' -diisocyanate, trimers of tolylene diisocyanate and reaction products of tolylene diisocyanate and an active hydrogen compound such as trimethylolpropane in a 3: 1 (molar ratio) can be used.

Further, it is preferable to use a compound having an isocyanate group bonded to a non-aromatic hydrocarbon ring, a trimer of a so-called alicyclic isocyanate compound, a reaction product with an active hydrogen compound, and the like. As the alicyclic isocyanate compound, isophorone diisocyanate, which is easily available on the market, is preferably used, but hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like can also be used.

The trimer of isophorone diisocyanate and the reaction product of isophorone diisocyanate and trimethylolpropane in a 3: 1 (molar ratio) ratio are preferred as the isocyanate compound used in the present invention, and among them, the trimer of isophorone diisocyanate is more preferred. A plurality of isocyanate compounds may be used in combination.

As the (meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with the isocyanate compound, a (meth) acryloyl compound having a hydroxyl group and/or a carboxyl group is cited. Hereinafter, the "(meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with an isocyanate compound" may be simply referred to as "specific (meth) acryloyl compound".

The reaction product of an isocyanate compound and a specific (meth) acryloyl compound having a hydroxyl group is generally referred to as "urethane acrylate". The reaction product of the isocyanate compound and the specific (meth) acryloyl compound having a carboxyl group is a compound having a structure in which a polymerizable (meth) acryloyl group is bonded via an amide group. These compounds are described below.

As the specific (meth) acryloyl compound having a hydroxyl group, a hydroxyl ester which is a reaction product of (meth) acrylic acid and a polyhydroxy compound is a representative compound. Further, compounds obtained by adding ethylene oxide, propylene oxide, caprolactone, and the like to the hydroxyl group of the hydroxy ester can be mentioned. There may be mentioned compounds obtained by esterifying a part of the hydroxyl groups of the hydroxy ester with a monocarboxylic acid.

Examples of such compounds include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, trimethylolpropane diacrylate, pentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate and other hydroxy (meth) acrylates, isocyanuric acid diacrylate, pentaerythritol diacrylate monostearate, 2-hydroxy-3-phenoxypropyl acrylate, and caprolactone, ethylene oxide, propylene oxide and ethylene oxide/propylene oxide adducts thereof.

In addition, the hydroxyl group of epoxy acrylate can also be used. Specific examples of the compound include epoxy acrylates obtained by reacting a compound having 2 epoxy groups in 1 molecule, such as neopentyl glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, hydrogenated bisphenol a diglycidyl ether, ethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether, with acrylic acid. These components also have an effect of increasing the crosslinking density because they have 2 (meth) acryloyl groups in 1 molecule.

Examples of the specific (meth) acryloyl compound having a carboxyl group include (meth) acrylic acid itself, and compounds produced by reacting a carboxylic acid anhydride, such as maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, with the above-mentioned hydroxyl (meth) acrylate.

Examples thereof include pentaerythritol triacrylate succinate monoester, dipentaerythritol pentaacrylate succinate monoester, pentaerythritol triacrylate maleate monoester, dipentaerythritol pentaacrylate maleate monoester, pentaerythritol triacrylate phthalate monoester, dipentaerythritol triacrylate phthalate monoester, pentaerythritol triacrylate tetrahydrophthalate monoester, dipentaerythritol pentaacrylate tetrahydrophthalate monoester, and the like.

When the isocyanate compound is reacted with the specific (meth) acryloyl compound, another active hydrogen compound capable of reacting with the isocyanate compound may be used in combination. That is, a compound having no (meth) acryloyl group and capable of reacting with an isocyanate group may be used in combination.

When such an active hydrogen compound is selected and used in combination according to the purpose, the softening point of the obtained curable composition may be increased, or the flexibility of the finally obtained cured coating film may be increased. As such an active hydrogen-containing compound, a hydroxyl-containing compound is generally used, but an amino-containing compound, a carboxyl-containing compound, and the like can also be used.

As the hydroxyl group-containing compound, polyhydric alcohols having 3 or more hydroxyl groups such as glycerin, trimethylolpropane, trimethylolethane, 1, 2, 6-hexanetriol, 2-hydroxyethyl-1, 6-hexanediol, 1, 2, 4-butanetriol, erythritol, sorbitol, pentaerythritol, dipentaerythritol, and the like; ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 2-methyl-1, 3-propanediol, 2-diethyl-1, 3-propanediol, 2-methyl-2-propyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 1, 6-hexanediol, 2-ethyl-1, 3-hexanediol, neopentyl glycol, 1, 3, 5-trimethyl-1, and aliphatic diols such as 3-pentanediol, 2, 4-trimethyl-1, 3-pentanediol, 1, 8-octanediol, 1, 9-nonanediol and 2-methyl-1, 8-octanediol, alicyclic diols such as 1, 4-cyclohexanediol and 1, 4-cyclohexanedimethanol, and aromatic diols such as benzenedimethanol and dihydroxyethoxybenzene.

In addition, high molecular weight polyols such as polyether polyol, polyester polyol, polyether polyol, polycarbonate polyol, and polyacryl polyol can also be used. Examples of the polyether polyol include bisphenol a, glycols such as ethylene glycol, propylene glycol and diethylene glycol, polyhydric alcohols having 3 or more hydroxyl groups such as glycerin, trimethylolethane, trimethylolpropane and pentaerythritol, and polytetramethylene ether glycols obtained by addition polymerization of alkylene oxides such as ethylene oxide and propylene oxide to polyamines such as ethylenediamine and toluenediamine and ring-opening polymerization of tetrahydrofuran.

Examples of the polyester polyol include those obtained by polycondensation reaction of a dicarboxylic acid such as succinic acid, adipic acid, sebacic acid, azelaic acid or phthalic acid, or a carboxylic acid such as tricarboxylic acid or tetracarboxylic acid such as trimellitic acid or pyromellitic acid, with a diol such as ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 2-diethylpropanediol, 2-ethyl-2-butylpropanediol, 1, 6-hexanediol, neopentyl glycol, diethylene glycol, 1, 4-cyclohexanediol or 1, 4-cyclohexanedimethanol, a triol such as trimethylolpropane or glycerin, or a triol such as bisphenol a or an aromatic polyhydroxy compound such as bisphenol F.

Examples of the polyetherester polyol include products obtained by reacting an alkylene oxide with a polyester diol, products obtained by reacting the above dicarboxylic acids or anhydrides thereof with an ether group-containing diol or a mixture of the ether group-containing diol and another diol, and poly (polytetramethylene ether) adipate. Examples of the polycarbonate polyol include those obtained by a dealcoholization condensation reaction of a polyol with a dialkyl carbonate such as dimethyl carbonate or diethyl carbonate, a dephenolization condensation reaction of a polyol with diphenyl carbonate, and a deethylenedicoupling reaction of a polyol with ethylene carbonate. Examples of the polyhydric alcohol used in the condensation reaction include aliphatic diols such as 1, 6-hexanediol, diethylene glycol, propylene glycol, 1, 4-butanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 2-diethylpropanediol, 2-ethyl-2-butylpropanediol, and neopentyl glycol, and alicyclic diols such as 1, 4-cyclohexanediol and 1, 4-cyclohexanedimethanol.

Examples of the amino group-containing compound (amine compound) include hexamethylenediamine, xylylenediamine, isophoronediamine, and N, N-dimethylethylenediamine. In addition, aminoalcohols such as monoethanolamine and diethanolamine can also be used as the active hydrogen-containing compound.

Examples of the compound having a carboxyl group (organic carboxylic acid) include lauric acid, stearic acid, oleic acid, palmitic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid.

In these active hydrogen compounds other than the specific (meth) acryloyl compound, the molar ratio of the reactive group of the active hydrogen compound to the reactive group of the specific (meth) acryloyl compound is preferably 50% or less, and particularly preferably 40% or less, in order not to impair the characteristics of the reaction product of the isocyanate compound and the specific (meth) acryloyl compound.

The reaction of the isocyanate compound and the specific (meth) acryloyl compound is preferably carried out using a solvent. By using a solvent, the reaction can be easily controlled, and the viscosity of the reaction product can be adjusted. As the solvent, inert solvents commonly used in this reaction are used, for example, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate, butyl acetate and isobutyl acetate, glycol ether ester solvents such as diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate and ethyl-3-ethoxypropionate, ether solvents such as tetrahydrofuran and dioxane, aprotic polar solvents such as N-methylpyrrolidone, and the like.

The reaction may be carried out by adding a reaction raw material to a solvent so that the concentration of the reaction product in the reaction product liquid becomes 30 to 80 wt%, and if necessary, reacting the reaction product liquid in the presence of 0.01 to 0.1 wt% of an organic tin catalyst with respect to the reaction raw material at 50 to 80 ℃. The charging ratio of the isocyanate compound, the specific (meth) acryloyl compound and, optionally, another active hydrogen compound used in combination therewith is preferably 0.5 mol or more, particularly preferably 1 mol or more, of the functional groups of the specific (meth) acryloyl compound and the other active hydrogen compound capable of reacting with the isocyanate compound, based on 1 mol of the isocyanate group of the isocyanate compound. The reaction time is usually about 3 to 8 hours, but it is preferable to keep track of the isocyanate group content in the reaction product liquid by analysis and stop the reaction when the target value is reached.

The ionizing radiation curable composition of the present invention is a reaction product of the isocyanate compound thus prepared and the specific (meth) acryloyl compound, and a reaction product having a softening point of 40 ℃ or higher is used. The softening point of the ionizing radiation curable composition is preferably 50 ℃ or higher, more preferably 60 ℃ or higher. When the softening point of the ionizing radiation curable composition is less than 40 ℃, blocking (blocking) occurs in the coating film before curing, and the emboss forming property is poor.

The softening point defined in the present invention means a softening point measured under the following conditions for a portion from which the solvent is removed from the reaction product.

Using a machine: レオメトリツクス corporation, ARES-2KFRTNI

Measurement model: dynamic viscoelasticity temperature dependence test, 25mm parallel plates

Measurement temperature range: -50 to 150 DEG C

Vibration frequency: 1 rad/sec

The temperature at which the melt viscosity reached 5000 Pa.s as measured under the above conditions was defined as the softening point

The (meth) acryl group in the ionizing radiation curable composition of the present invention has a molecular weight of an olefinic double bond (-C ═ C-) of 24, preferably 5% by weight or more, and more preferably 10% by weight or more. When the amount of the (meth) acryl group is small, the crosslinking density after curing by ionizing radiation is lowered, the solvent resistance, heat resistance and the like are insufficient, and peeling failure, sagging in forming a film of vinyl chloride and the like are caused.

The content of olefinic double bonds is measured by IR, NMR, etc., but when the production process is known, it can be determined by calculation from the amount charged.

The coating liquid used in the present invention is preferably configured to contain a siloxane compound in addition to the above components in order to impart releasability to the surface of the ionizing radiation-curable film. In the present invention, as described below, when the ionizing radiation curable film has a structure of two or more layers, a layer containing no siloxane compound may be provided.

In the present invention, it is preferable that the proportion of silicon derived from siloxane existing on the surface of the ionizing radiation curing film (i.e., the surface of the synthetic leather that is peeled off from the synthetic leather) is 5 to 30%, and that the proportion of silicon derived from siloxane existing on the surface of the ionizing radiation curing film is 5% or more when the step of producing synthetic leather using the release paper is repeated 5 times. In the present specification, the term "proportion of silicon derived from siloxane" refers to the atomic percent of silicon atoms (hydrogen atoms are ignored, among atoms detected from the surface of the release paper by X-ray photoelectron spectroscopy (hereinafter, XPS)). By setting the proportion of silicon present on the surface of the ionizing radiation curing film to 5 to 30%, excellent releasability can be maintained even when used in the production of synthetic leather. It has been found that if the proportion of silicon derived from siloxane on the surface of the ionizing radiation curing film is 5% or more when the step of producing synthetic leather using the release paper of the present invention is repeated 5 times, the releasability of the release paper can be sufficiently maintained even when the synthetic leather is produced using the release paper repeatedly.

The content of the siloxane compound in the coating liquid containing the ionizing radiation curable composition is 20% by weight or less, preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight. When the silicone compound is more than 20% by weight, the coating film becomes tacky and the cost increases, and when less than 0.5% by weight, the effect of improving the releasability is insufficient.

The siloxane compound used in the present invention may be either reactive or non-reactive. Examples of the reactive silicone compound include (meth) acryloyl-modified, vinyl-modified, amino-modified, mercapto-modified, epoxy-modified, carboxyl-modified, phenol-modified, and alcohol-modified silicone compounds.

Specific examples of the compound include (meth) acryloyl-modified siloxane include X-22-164B, X-22-164C (manufactured BY shin-Etsu chemical industries), FM-0711, FM-0721, FM-0725 (manufactured BY チツソ), vinyl-modified siloxane include XF40-A1987 (manufactured BY Toshiba シリコ - ソ), amino-modified siloxane include TSF4700, TSF4702, TSF4705 (manufactured BY Toshiba シリコ - ソ), X-22-161AS, KF393, KF864 (manufactured BY shin-Etsu chemical industries), BY16-208, SF8417 (manufactured BY letters レ. ダウコ - ニソグ. シリコ ソ), mercapto-modified siloxane include X-22-167B, KF-2001 (manufactured BY shin chemical industries), epoxy-modified siloxane, YF-3965, TSF-4730 (manufactured BY Toshiba シリコ - ソ Co.), KF105, X-22-169AS (manufactured BY shin-Etsu chemical industries Co.), SF8421, SF8413 (manufactured BY imperial レ - ダウコ - ニソグ - シリコ ソ Co., Ltd.), TSF4770, XF-A9248 (manufactured BY Toshiba シリコ - ソ Co., Ltd.), X-22-162A, X-22-3701E (manufactured BY shin-Etsu chemical industries Co., Ltd.), SF8418, BY16-750 (manufactured BY Du レ - ダウコ - ニソグ - シリコ ソ Co., Ltd.), phenol-modified siloxanes X-22-165B (manufactured BY shin-Etsu chemical industries Co., Ltd.), BY16-752, BY 8-150C (manufactured BY Duoji レ - ダウコ - ニソグ - シリコ ソ Co., Ltd.), alcohol-modified siloxanes, examples thereof include TSF4750, TSF4751 (manufactured BY Toshiba シリコ - ソ Co.), BY16-848, BY16-201 (manufactured BY Chinese imperial sciences レ. ダウコ - ニソグ. シリコ ソ Co.), FM-4411, FM-4425, FM-0411, FM-0425, FM-DA21 (manufactured BY チツソ Co.), and the like.

In addition, silicone compounds synthesized using these reactive silicones can also be used. The synthesized siloxane compound may or may not further have a reactive group. Examples of the silicone compound synthesized using a reactive silicone include silicone-modified (meth) acryl polymers and silicone-modified (meth) acrylates using (meth) acryloyl-modified silicones, silicone-modified epoxy acrylates using epoxy-modified silicones, silicone-modified urethane polymers and silicone-modified urethane acrylates using alcohol-modified silicones, and the like. Among them, silicone-modified urethane acrylate is particularly preferable.

The non-reactive silicone compound may be a silicone compound having no reactive group. Specific examples of the compound include dimethylpolysiloxane such as TSF451, YF3800 (manufactured by Toshiba シリコ - ソ Co.), KF96A (manufactured by shin-Etsu chemical industries Co.), SH200 (manufactured by Egyo レ, ダウコ, ニソグ, シリコ ソ Co.), methylphenylpolysiloxane such as TSF433, TSF434 (manufactured by Toshiba シリコ - ソ Co.), SH510, SH702 (manufactured by Egyo レ, ダウコ, ニソグ, シリコ ソ Co.), and polyether-modified siloxane such as TSF4440, TSF4445 (manufactured by Toshiba シリコ - ン Co.), KF-351, KF-353 (manufactured by shin-Etsu chemical industries Co.), SH3746, SH-3748 (manufactured by Bao レ, ダウコ, ニソグ, シリコ ソ Co.), SS-2803, and SS-2801 (manufactured by Japanese ユニカ -co.).

These siloxane compounds may be used alone, or two or more kinds thereof may be used, or a mixture of both reactive and non-reactive compounds may be used. In addition, from the viewpoint of compatibility with other components, the siloxane compound is preferably an aromatic, alicyclic or compound having a ring structure such as an isocyanuric acid skeleton. Examples of the siloxane compound having a ring structure include siloxane compounds such as methylphenylsiloxane having a phenyl group introduced into a side chain thereof, and methods of introducing a ring structure using a reactive siloxane. Examples of the method for introducing a ring structure using a reactive siloxane include siloxane compounds in which a phenyl group is introduced by copolymerizing a (meth) acryloyl-modified siloxane and styrene, siloxane compounds in which a ring structure is introduced into a siloxane-modified urethane polymer or a siloxane-modified urethane acrylate using monomers of diphenylmethane diisocyanate, naphthalene diisocyanate, and isophorone diisocyanate, terpolymers thereof, and the like. These siloxane compounds having a ring structure may further have a reactive group or may not have a reactive group.

In the present invention, the ionizing radiation curable film layer is preferably formed in two or more layers because pinholes are further reduced by providing two or more layers. Preferably, at least one of the two or more layers contains 0.5 to 20 wt% of a siloxane compound. More preferably, the uppermost layer (i.e., the release surface of the synthetic leather) disposed on the side opposite to the support side contains 0.5 to 20% by weight of the siloxane compound. By containing the siloxane compound on the surface of the uppermost layer in this way, the releasability can be improved, and the releasability of the release paper can be sufficiently maintained even when the release paper is repeatedly used to produce synthetic leather. When the ionizing radiation curable film is formed in a plurality of layers, the layer other than the uppermost layer may not contain a siloxane compound.

The coating liquid used in the present invention may contain, as optional components, a resin having film-forming properties, an inorganic pigment, and the like, in addition to the siloxane compound, in order to modify the curing properties of the reaction product.

In this case, the inorganic pigment is preferably contained in the lowermost layer in an amount of 0.5 to 50 wt%, particularly preferably 1 to 10 wt%. Examples of the inorganic pigment used in the pigment include talc, kaolin, silica, calcium carbonate, barium sulfate, titanium oxide, and zinc oxide.

In a more preferred embodiment, the inorganic pigment is contained in an amount of 0.5 to 50 wt% in the lowermost layer disposed on the support side, and the siloxane compound is contained in an amount of 0.5 to 20 wt% in the uppermost layer disposed on the side opposite to the support side. In this way, by containing the inorganic pigment in the layer on the support side and the silicone compound in the layer opposite to the support side (layer on the release surface side of the synthetic leather), excellent releasability can be provided. The reason for this is not clear, but when the inorganic pigment and the siloxane compound are contained in the same ionizing radiation curable film layer, the siloxane compound may be affected by the inorganic pigment (for example, the siloxane compound may be adsorbed on the inorganic pigment) depending on the coating conditions of the coating liquid. In addition, for example, when importance is attached to a design effect such as a mat feel to the surface of the release paper, an inorganic pigment may be added to the uppermost layer disposed on the side opposite to the side of the support.

As the resin having film-forming properties, methacrylic resin, chlorinated polypropylene, epoxy resin, polyurethane resin, polyester resin, polyvinyl alcohol, polyvinyl acetal, and the like can be used. These resins having film-forming properties may or may not have a reactive group. Examples of the reactive group include a (meth) acryloyl group, a vinyl group, an amino group, a mercapto group, an epoxy group, a carboxyl group, a phenol group, and a hydroxyl group. Methacrylic resins are preferred from the viewpoint of adhesion to substrates, film formation properties, and the like, but methacrylic resins having a glass transition temperature (Tg) of 40 ℃ or higher are preferred from the viewpoint of embossability, methacrylic resins having a Tg of 50 ℃ or higher are more preferred, and maleic anhydride, methacrylic acid, styrene, hydroxyethyl methacrylate, maleimide group-containing methacrylate, isobornyl group-containing methacrylate, and the like may be used as a copolymerization component in addition to ordinary methacrylic compounds.

The amount of the resin having film-forming property to be used is usually 70% by weight or less, preferably 1 to 70% by weight, more preferably 20 to 60% by weight as the content of the coating liquid. When the film-forming resin is more than 70% by weight, that is, when the content of the ionizing radiation curable composition is less than 30% by weight, the heat resistance after curing with ionizing radiation is insufficient. By blending an appropriate amount of a resin having film-forming properties, the adhesion to a base material, film-forming properties, and the like can be improved.

In addition to or instead of the above-mentioned resin or siloxane compound having film-forming properties, the coating liquid may contain a reactive monomer, a reactive oligomer, a pigment, a photopolymerization initiator, a polymerization inhibitor, a colorant, a surfactant, and the like.

As the reactive monomer, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, trimethylolpropane triacrylate, tris (acryloyloxyethyl) isocyanurate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and the like are preferably used.

As the reactive oligomer, epoxy acrylate, urethane acrylate, polyester acrylate, polyether acrylate, and the like are preferably used.

As the photopolymerization initiator, benzoin ethyl ether, acetophenone, diethoxyacetophenone, benzyl dimethyl ketal, 2-hydroxy-2-methylpropiophenone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1, 1-hydroxycyclohexyl phenyl ketone, benzophenone, p-chlorobenzophenone, Michler's ketone, N-dimethylaminobenzoic acid isoamyl ester, 2-chlorothioxanthone, 2, 4-diethylthioxanthone, and the like are preferably used.

In addition, a solvent is appropriately added for coating and a viscosity for easy coating is achieved. Examples of the solvent include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester solvents such as ethyl acetate, butyl acetate and isobutyl acetate, glycol ether ester solvents such as diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether, 3-methyl-3-methoxybutyl acetate and ethyl-3-ethoxypropionate, ether solvents such as tetrahydrofuran and dioxane, and aprotic polar solvents such as N-methylpyrrolidone.

Ionizing radiation curing film

The ionizing radiation-curable film constituting the release paper of the present invention is formed by applying the coating liquid and curing the coating liquid. The coating liquid may be obtained by diluting the solid content by 100 parts by weight with a solvent of 10 to 1000 parts by weight. The silicone compound can be suitably transferred to the surface in the step of drying while imparting a viscosity suitable for coating, for example, a viscosity of 10 to 3000mPa · s at 25 ℃ by dilution with a solvent.

As a coating method of the coating liquid, a known method such as direct gravure coating, reverse gravure coating, gravure offset coating, micro gravure coating, direct roll coating, reverse roll coating, curtain coating, blade coating, air knife coating, bar coating, die coating, spray coating is used, and after coating on a paper substrate, a coating film is formed by evaporating a solvent in a drying furnace.

If the coating liquid reaches 1-40 g/m according to the dry weight of the solvent after evaporation²Preferably 5 to 20g/m²By applying the above method, a good embossing property can be obtained.

The ionizing radiation-curable film layer is preferably formed in two or more layers, and the formation of two or more layers further reduces pinholes. When the ionizing radiation curable film layer is formed in two or more layers, the inorganic pigment is preferably contained in an amount of 0.5 to 50 wt%, particularly preferably 1 to 10 wt%, in the ionizing radiation curable film layer at the lowermost layer. As the inorganic pigment, talc, kaolin, silica, calcium carbonate, barium sulfate, titanium oxide, zinc oxide, or the like can be suitably used.

The ionizing radiation curing film layer may contain a siloxane compound. In this case, the siloxane compound may be contained only in the uppermost layer of the ionizing radiation curable film layer, or may be contained in each layer.

Since the coating film formed by applying and drying the coating liquid on the support is non-tacky, it can be wound up together with the paper substrate without blocking after drying, and embossing for subsequent processing can be performed off-line. Further, by appropriately setting the temperature of the embossing roll and the softening temperature of the coating liquid, the coating liquid does not adhere to the embossing roll, and good forming properties can be obtained.

The embossing is generally a method of forming by transferring a metal embossing roller having an uneven pattern, but a belt type or a flat plate type pressing device may be used. When the embossing roll is used, there are both-side embossing in which the back-up roll is formed into concave embossing with respect to the convex embossing of the embossing roll, and single-side embossing in which the back-up roll is formed without concave and convex embossing.

When the coating liquid is applied to the support, the coating liquid is heated to 50 to 150 ℃ by using the embossing device to perform forming. The temperature is preferably in a range higher than the softening point of the ionizing radiation curable composition contained in the coating liquid and lower than the temperature at which the resin melts. The heating method is a preheating method in which the coating liquid is heated in advance immediately before embossing, although the roller itself is usually heated by passing steam or the like to the embossing roller.

In order to obtain the above-mentioned excellent non-blocking property and shape-imparting property, the softening point of the ionizing radiation curable composition is 40 ℃ or higher, preferably 50 ℃ or higher, as described above. When the softening point is less than 40 ℃, the non-blocking property and the forming property become insufficient.

After the embossing, the curable coating film coated with the coating liquid is cured by irradiating ultraviolet rays or electron beams from the curable coating film side. As the ultraviolet light source, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a tungsten lamp, or the like is used. The electron beam irradiation method may be a scanning method, a curtain beam method, a wide beam method, or the like, and the acceleration voltage of the electron beam is preferably 50 to 300 kV.

Fig. 1 is a diagram showing an example of a process for producing release paper according to the present invention. In the figure, 1 denotes a take-up roller, 2 denotes an embossing roller, 3 denotes a backup roller, 4 denotes a take-up roller, 5 denotes a paper with a curable coating film, 6 denotes a paper with a curable coating film having an embossing, and 7 denotes an embossed release paper. Further, a indicates an embossing process, and B indicates an ionizing radiation irradiation process.

(2) Support for embossed release paper for synthetic leather production

Fig. 2 shows a support of the release paper for producing synthetic leather according to the present invention.

The support 11 of the embossed release paper for synthetic leather production of the present invention comprises a base paper 12 and a clay coating layer 13 formed thereon. The base paper 12 is made of a neutral paper having heat resistance such that the tensile strength measured by a measurement method based on the JIS P8113 standard is maintained at least at 10kN/m in the longitudinal direction even when left standing at 230 ℃ for 3 minutes, and the tear strength measured by a measurement method based on the JIS P8116 standard is maintained at 500mN or more in both the longitudinal and transverse directions. The clay coating layer 13 formed on the base paper has a smoothness of 100 seconds or more measured by a test method based on JIS P8119 standard, and is formed so that surface irregularities due to pulp fibers of the base paper are absorbed.

Therefore, the release paper using the support of the present invention has high heat resistance to withstand a temperature of 230 ℃ required for the production of vinyl chloride resin synthetic leather, and can withstand repeated use for 5 times or more in the production of synthetic leather.

As the pulp used for the base paper, pulp in which softwood pulp (N material) and hardwood pulp (L material) are mixed can be suitably used in order to obtain necessary strength and smoothness. In this case, the mixing ratio of the hardwood pulp (L material) is preferably 50 to 90% for improving the smoothness. When the mixing ratio of the hardwood pulp (L material) is less than 50%, smoothness is not preferable. On the other hand, if the amount is more than 90%, the strength of the base paper is lowered, which is not preferable. Further, a filler, a paper strength improver, a stabilizer, and the like may be added to the pulp raw material.

In order to impart sufficient heat resistance to the release paper, the base paper must be neutral paper. Examples of the filler for neutral papermaking include Alkyl Ketene Dimer (AKD), alkenyl succinic anhydride, and cationic polymers. Among these, alkyl ketene dimers are preferred because they are relatively stable. In addition, when aluminum sulfate is used as the fixing agent, the strength of paper is significantly reduced at a high temperature of 200 ℃ or higher, and therefore aluminum sulfate should not be used.

The basis weight of the base paper is preferably 100 to 200g/m from the viewpoints of strength as a release paper product, workability in processing synthetic leather, durability of the release paper when repeatedly used, suitability for embossing, and the like². The weight per unit area is less than 100g/m²In this case, curling and waving are likely to occur during the production of the synthetic leather. On the other hand, the weight per unit area is more than 200g/m²In this case, the emboss processability is deteriorated, and the release paper becomes thick, so that the roll diameter becomes large, and the work efficiency is lowered.

The base paper can be made by a fourdrinier multi-cylinder paper machine, a short-cylinder multi-cylinder paper machine, a fourdrinier/short-cylinder combined multi-cylinder paper machine, a fourdrinier/cylinder combined multi-cylinder paper machine, a fourdrinier yankee paper machine, and the like.

The clay coating layer is made of a coating material containing a binder such as styrene-butadiene latex, vinyl acetate latex, acrylic latex, starch, casein, etc., and an inorganic pigment such as kaolin, calcium carbonate, talc, silica, titanium oxide, aluminum hydroxide, etc. The coating material can be applied by an air knife coater, a blade coater, a bar coater, a roll coater, a reverse roll coater, a gravure coater, a die coater, a notch bar coater, a flow coater, or the like, or by a combination of these coaters. In order to obtain the required smoothness, i.e., the smoothness is 100 seconds or more in the test method based on JIS P8119, the coating amount is preferably 5 to 40g/m². The coating weight is less than 5g/m²The required smoothness is not obtained, and on the other hand, the smoothness is more than 40g/m²In time, embossing is givenAnd (5) reducing.

The clay coating of the base paper may be performed continuously in the papermaking step or in another step. Further, after the coating material is applied, the surface smoothness can be improved by passing the coating material through a calender roll.

In a more preferred embodiment of the support of the present invention, the base paper is a neutral paper made of a mixed pulp of hardwood pulp and softwood pulp having a mixing ratio of hardwood pulp (L material) of 50 to 90%, and is made to have a heat resistance such that even when left standing at 230 ℃ for 3 minutes, the tensile strength measured by the measurement method according to JIS P8113 is maintained at least at 10kN/m in the longitudinal direction, and the tear strength measured by the measurement method according to JIS P8116 is maintained at 500mN or more in both the longitudinal and transverse directions. In order to obtain such a support, it is preferable to use a base paper having a thickness of 5 to 40g/m²The coating amount of (3) is a clay coating layer having a smoothness of 100 seconds or more as measured by a measurement method based on JIS P8119. In the support of the release paper for producing synthetic leather, a smooth ionizing radiation curable resin layer can be formed on the clay coating layer. That is, the surface morphology of the ionizing radiation cured film obtained by embossing the ionizing radiation curable resin layer provided on the support and then curing the resin layer by irradiation with ionizing radiation is not affected by the unevenness due to the base paper fibers.

Fig. 3 shows a release paper for synthetic leather production formed using the support 11 of the release paper for synthetic leather production of the present invention.

The release paper for producing synthetic leather of the present invention is obtained by the following steps: a step of providing an uncured ionizing radiation curable resin film on the clay coating layer of the support; a step of embossing the uncured ionizing radiation curable resin film; and a step of irradiating the ionizing radiation-curable resin film with ionizing radiation to cure the resin after the embossing step.

The embossed release paper for synthetic leather production of the present invention has high heat resistance to withstand a temperature of 230 ℃ required for the production of vinyl chloride resin synthetic leather, and can be repeatedly used 5 times or more in the production process of synthetic leather. Further, since the release paper does not stretch during transfer, the release paper can be transferred to the skin layer with high transfer accuracy using a urethane resin, polyvinyl chloride, or the like. Further, the base paper has a glossy surface because it is not affected by the unevenness due to the pulp fibers. Therefore, the release paper having the synthetic leather with the glossy texture can be produced.

As the support in other embodiments of the present invention, non-coated papers such as security papers (wood-free papers), kraft papers, machine-glazed papers, plain white pressed papers, glass papers, and cup base papers, as well as art papers, coated papers such as coated papers and cast coated papers provided with an inorganic pigment coating layer, synthetic papers not using natural pulp, and the like can be used. In particular, when used for the production of PVC leather, neutral paper is more preferable than acid paper because heat resistance to high temperature processing of 200 ℃ or higher is required. In acid paper, a rosin-based filler using aluminum sulfate as a fixing agent is used as a filler, but in neutral paper, a neutral rosin-based filler, such as Alkyl Ketene Dimer (AKD) or Alkenyl Succinic Anhydride (ASA), is used without using aluminum sulfate as a fixing agent.

In addition, in the embossing, in order to have good shape, sufficient strength and moderate smoothness, the pulp is preferably a mixed pulp of coniferous pulp and broadleaf pulp, the coniferous pulp contains at least 20% and the weight per unit area is 80-250 g/m²。

In addition, when the interstitial layer is formed of the film-forming resin or a mixture of the resin and an inorganic pigment, the generation of pinholes due to the penetration of the coating liquid can be suppressed, and smoothness can be imparted to the support, which is preferable.

Examples of the film-forming resin used for forming the interstitial layer include polyvinyl alcohol, acrylic resin, styrene acrylic resin, cellulose derivatives, polyester resin, polyurethane resin, melamine resin, alkyd resin, aminoalkyd resin, polyvinyl chloride resin, polyvinylidene chloride resin, and these resins may be mixed and used.

Examples of the inorganic pigment to be added include talc, kaolin, silica, calcium carbonate, barium sulfate, titanium oxide, zinc oxide, and the like, and the inorganic pigment is usually added in an amount of 0.5 to 70% by weight based on the resin having film-forming properties. The interstitial layer may be 0.5 to 20g/m²If the amount is too small, the effect of the filler cannot be exerted, and if it is too large, the embossability is impaired. The filler material can be applied in the same manner as the coating liquid containing the ionizing radiation curable resin composition.

(3) Synthetic leather manufactured using embossed release paper and method for manufacturing same

Synthetic leather

The synthetic leather produced using the above-mentioned embossed release paper has a silicone-derived silicon content of 20% or less on the surface of the side from which the release paper is peeled. When the release paper is peeled off to produce a synthetic leather, a silicone compound is present on the surface of the synthetic leather obtained to some extent, which is transferred from the release paper. The present inventors confirmed this fact from XPS analysis of the surface of the release paper and the surface of the synthetic leather. That is, the amount of the siloxane compound (the ratio of silicon derived from siloxane) transferred from the release paper is smaller than the ratio of silicon derived from siloxane on the surface of the release paper, even if the amount is the largest. The present inventors have found that even when a synthetic leather is produced by repeatedly using a release paper, the proportion of silicon derived from siloxane present on the surface of the release paper from which the silicone is removed is 20% or less.

Further, even when the synthetic leather is repeatedly produced by using the release paper of the present invention as described above, the proportion of silicon derived from siloxane present on the release surface of the synthetic leather is 20% or less. Therefore, even when the release paper is repeatedly used, the excellent releasability of the release paper is maintained.

Method for producing synthetic leather of first embodiment

A method for producing a synthetic leather according to a first aspect of the present invention is a method for producing an embossed release paper that includes at least paper as a support and an ionizing radiation curing film provided on the paper, and that is obtained by embossing the curing film. The release paper is described later.

First, a polyurethane resin composition is applied to the ionizing radiation cured film embossed on the release paper, and the film is heated and dried to form a skin-like layer. As the polyurethane resin composition, a one-pack type of polyester aromatic isocyanate urethane, polyether aromatic isocyanate urethane, polycarbonate aromatic urethane, polyester aliphatic isocyanate urethane, polyether aliphatic urethane, and polycarbonate aliphatic isocyanate urethane can be suitably used. The polyurethane resin to be applied is usually dried by heating at 90 to 140 ℃ although it depends on the composition. By using the release paper used in the present invention, the synthetic leather can be embossed well without deformation or the like even when dried at a high temperature of 150 to 250 ℃. The polyurethane resin layer serving as the skin-like layer of the synthetic leather is formed on the release paper embossed in this manner.

Next, a base fabric is bonded to the skin layer with an adhesive to form a synthetic leather layer. As the binder, a one-part urethane resin, a two-part curable urethane resin, a melamine resin, or the like can be used, but when strength is required, a two-part curable urethane resin can be suitably used. The two-component curable urethane resin is used in a two-component form by mixing an aromatic or aliphatic diisocyanate as a curing agent with a polyester, polyether or polycarbonate prepolymer diol as a main component. The compound was reacted and used as a binder. After applying an adhesive to the skin layer, a base fabric is attached to the skin layer, and the adhesive is dried and cured, thereby attaching the skin layer and the base fabric. The bonding of the surface layer and the base fabric is usually carried out by reacting the adhesive in a curing chamber at 40 to 70 ℃ for 2 to 3 days. In the present invention, the skin layer and the base fabric may be bonded by either thermal lamination or wet lamination, but thermal lamination is more preferable. The surface layer and the base fabric are bonded to each other with the adhesive in this way, thereby forming a synthetic leather.

Then, the release paper is peeled from the synthetic leather to obtain the synthetic leather. By using the release paper used in the present invention, the release properties are excellent even when the PU resin is used as the skin-like layer, and therefore, the synthetic leather can be produced by repeatedly using the release paper.

Process for producing synthetic leather of the second embodiment

In the method for producing synthetic leather according to the second aspect of the present invention, a polyurethane resin composition is applied to the ionizing radiation-cured film embossed on the release paper, and the resulting film is heated and dried to form a skin-like layer, using the same method for producing release paper as described above. This step is the same as the first embodiment, and the description thereof is omitted.

Then, a wet intermediate layer is laminated on the surface layer, and the surface layer and the wet intermediate layer are pressed together from the release paper side by a heat roll. In this way, the synthetic leather is obtained by laminating the rear skin layer and the wet intermediate layer. The pressing is carried out by using a hot roller, and the hot roller is preferably 110-190 ℃. Here, the wet intermediate layer is obtained by applying a solution in which a urethane resin is dissolved in Dimethylformamide (DMF) to a base fabric, immersing the base fabric in water, and solidifying the urethane by replacing DMF with water. The microporous layer is formed in the wet intermediate layer obtained in such a step. Therefore, by incorporating the wet intermediate layer in synthetic leather, soft and rich synthetic leather can be obtained.

Then, the synthetic leather can be produced by cooling the portion to be synthetic leather (the laminate obtained by laminating the skin-like layer and the intermediate synthetic leather layer) and then peeling the release paper.

Method for producing synthetic leather of the third embodiment

A method for producing synthetic leather according to a third aspect of the present invention is a method for producing a release paper, using the same method as described above, wherein a vinyl chloride resin composition is applied to an ionizing radiation-cured film embossed on the release paper, and heated and dried to form a skin-like layer. Examples of the vinyl chloride resin composition include polymers obtained by copolymerizing vinyl chloride monomer and monomers such as vinyl chloride monomer and vinyl acetate, ethylene, propylene, and maleic acid ester. A vinyl chloride resin composition is obtained by adding a plasticizer such as a phthalic acid-based plasticizer or a fatty acid ester-based plasticizer to the above resin, pasting the mixture, and adding an antioxidant, a stabilizer, a filler, a pigment, and the like to the paste.

The vinyl chloride resin coated is usually cured by heating and drying at 200 to 250 ℃ depending on the composition. By using the release paper used in the present invention, the synthetic leather can be embossed well without deformation or the like even when dried at a high temperature of 200 to 250 ℃.

Next, a foamable vinyl chloride resin composition is applied to the skin layer containing a vinyl chloride resin, and the intermediate layer is formed by heating. As the foamable vinyl chloride resin composition, a composition obtained by adding a foaming agent such as azodicarbonamide or dinitrosopentamethylenetetramine to the same composition as that used for the skin layer can be used. Usually, the foamable vinyl chloride resin composition is applied to the skin layer and dried by heating at 180 to 250 ℃ to foam the foamable vinyl chloride resin and form the intermediate layer.

A synthetic leather layer was formed by bonding a base fabric to the intermediate layer with an adhesive. As the adhesive, a two-component curing type polyurethane adhesive or the like can be suitably used. After the adhesive is applied to the surface layer, a base fabric is attached to the surface layer, and the adhesive is dried and cured, thereby attaching the surface layer and the base fabric. The bonding step between the surface layer and the base fabric is usually carried out by reacting the adhesive in a curing chamber at 40 to 70 ℃ for 2 to 3 days. Thus, the resultant structure of skin layer/intermediate layer/adhesive/base fabric is a synthetic leather.

Then, the release paper is peeled from the synthetic leather to obtain the synthetic leather. By using the release paper used in the present invention, even when a PVC resin is used as the skin-like layer, the release paper is excellent in releasability, and therefore, the synthetic leather can be produced by repeatedly using the release paper.

Method for producing synthetic leather of the fourth embodiment

A method for producing synthetic leather according to a fourth aspect of the present invention is a method for producing a release paper, using the same method as described above, wherein a polyurethane resin composition is applied to an ionizing radiation-cured film embossed on the release paper, and heated and dried to form a skin-like layer. This step is the same as the first embodiment, and the description thereof is omitted.

Next, a foamable vinyl chloride resin composition is applied to the skin layer containing the polyurethane resin, and the intermediate layer is formed by heating. The intermediate layer is not described in detail as described above.

A synthetic leather layer was formed by bonding a base fabric to the intermediate layer with an adhesive. That is, the structure of skin layer/intermediate layer/adhesive/base fabric is formed into a synthetic leather.

Then, the release paper is peeled from the synthetic leather to obtain the synthetic leather. By using the release paper used in the present invention, even when synthetic leather (semi-synthetic leather) in which PU and PVC are combined is produced, the release paper is excellent in releasability, and therefore, the release paper can be repeatedly used to produce synthetic leather.

Examples

The present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

1.The embossed release paper of the first embodiment of the present invention

(1) Preparation of ionizing radiation-curable composition

The following five ionizing radiation curable compositions were prepared.

Ionizing radiation curable composition A

In a reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 206.1g of ethyl acetate and 133.5g of a trimer of isophorone diisocyanate (manufactured by degussa corporation, vestatat, T1890) were charged, and dissolved by raising the temperature to 80 ℃. After blowing air into the solution, 0.38g of hydroquinone monomethyl ether, 249.3g of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (ビスコ - ト 300, manufactured by Osaka organic chemical industries, Ltd.) and 0.38g of dibutyltin dilaurate were added. After allowing the reaction mixture to react at 80 ℃ for 5 hours, 688.9g of ethyl acetate was added thereto and the mixture was cooled. The infrared absorption spectrum analysis of the obtained reaction product liquid confirmed that the isocyanate group had disappeared in absorption. The softening temperature of the reaction product from which ethyl acetate was distilled off was 43 ℃.

Ionizing radiation curable composition B

A reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was charged with 256.67g of methyl ethyl ketone and 110g of a trimer of isophorone diisocyanate, and the mixture was heated to 80 ℃ to be dissolved. After blowing air into the solution, 0.30g of hydroquinone monomethyl ether, 381.2g of a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (KAYARAD DPHA, manufactured by Nippon chemical Co., Ltd.), 21.2g of 1, 4-butanediol and 0.30g of dibutyltin dilaurate were added. After allowing the reaction to proceed at 80 ℃ for 5 hours, 939.02g of methyl ethyl ketone was added thereto and the mixture was cooled. The infrared absorption spectrum analysis of the obtained reaction product liquid confirmed that the isocyanate group had disappeared in absorption. The softening temperature of the product obtained by distilling methyl ethyl ketone from the reaction product liquid was 42 ℃.

Ionizing radiation curable composition C

A reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was charged with 256.67g of methyl ethyl ketone and 110g of a trimer of isophorone diisocyanate, and the mixture was heated to 80 ℃ to be dissolved. After blowing air into the solution, 0.20g of hydroquinone monomethyl ether, 146.65g of a mixture of pentaerythritol tetraacrylate and pentaerythritol triacrylate, 30.08g of epoxy acrylate (epoxy ester 70PA, manufactured by Kyor chemical Co., Ltd.) and 0.20g of dibutyltin dilaurate were added. After allowing the reaction to proceed at 80 ℃ for 5 hours, 412.37g of methyl ethyl ketone was added thereto and the mixture was cooled. The obtained reaction product was analyzed by liquid infrared absorption spectroscopy, and it was confirmed that the isocyanate group absorption disappeared. The softening temperature of the product obtained by distilling methyl ethyl ketone from the reaction product liquid was 68 ℃.

Ionizing radiation curable composition D

256.67g of methyl ethyl ketone and 110g of isophorone diisocyanate (product of degussa corporation, VESTANAT, IPDI) were charged into a reactor equipped with a stirrer, reflux condenser, dropping funnel and thermometer, and dissolved by raising the temperature to 80 ℃. After blowing air into the solution, 0.40g of hydroquinone monomethyl ether, 448.53g of a mixture of pentaerythritol tetraacrylate and pentaerythritol triacrylate and 0.40g of dibutyltin dilaurate were added. After allowing the reaction to proceed at 80 ℃ for 5 hours, 1046.57g of methyl ethyl ketone was added thereto and the mixture was cooled. The infrared absorption spectrum analysis of the obtained reaction product liquid confirmed that the isocyanate group had disappeared in absorption. The distillation removal of methyl ethyl ketone from the reaction product liquid was a viscous liquid, and the softening temperature could not be measured.

Ionizing radiation curable composition E

A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (manufactured by Nippon chemical Co., Ltd., KAYARAD DPHA) was used as it is.

(2) Preparation of resin with film-forming property

The following three resins having film-forming properties were prepared.

Resin a

A solution prepared by dissolving 30g of isobornyl methacrylate, 65g of methyl methacrylate and 5g of glycidyl methacrylate in 200g of toluene was heated in a reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and when the temperature was raised to 65 ℃ and 2 hours after the temperature reached 65 ℃, 0.5g of 2, 2' -azobis (2, 4-dimethylvaleronitrile) was added thereto and reacted at 65 ℃ for 5 hours to obtain a copolymer. Thereafter, while blowing air, the temperature was intermittently raised to 108 ℃ and 0.2g of hydroquinone monomethyl ether and 0.2g of triphenylphosphine were added, and then 2.5g of acrylic acid was added to react for 5 hours, thereby obtaining a film-forming resin a having an acryloyl group.

Resin b

5g of 4-hydroxyethyl methacrylate, 20g of isobornyl methacrylate, 75g of methyl methacrylate, 200g of methyl ethyl ketone and 0.5g of 2, 2' -azobis (2, 4-dimethylvaleronitrile) were charged into a reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and polymerized at 65 ℃ for 6 hours. Thereafter, 0.2g of hydroquinone monomethyl ether and 0.2g of dibutyltin dilaurate were added thereto by blowing air, 10.7g of an isocyanate group-containing acrylate (VI-1, manufactured by Cikawa chemical Co., Ltd.) was added thereto, and the temperature was raised to 80 ℃ to conduct a reaction for 5 hours, thereby obtaining a film-forming resin b having an acryloyl group.

Resin c

A commercially available product of a methacrylate resin (パラペツト GF, manufactured by クラレ) was used as it was.

(3) Preparation of siloxane Compounds

The following three siloxane compounds were prepared.

Siloxane compound alpha

A reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was charged with 23.3g of methyl ethyl ketone, 10g of isophorone diisocyanate, 20.4g of a mixture of pentaerythritol tetraacrylate and pentaerythritol triacrylate, 0.10g of dibutyltin dilaurate and 0.10g of hydroquinone monomethyl ether, and after blowing air into the solution, the reaction was carried out at 25 ℃ for 3 hours, then at 80 ℃ intermittently, for 5 hours, 240.8g of an alcohol-modified siloxane (manufactured by チツソ company, FMDA21) was added to the resultant reaction mixture, and after further reaction for 5 hours, 609.3g of methyl ethyl ketone was added and cooled to obtain a siloxane-modified urethane acrylate (siloxane compound. alpha.) containing an acryloyl group and siloxane.

Siloxane compound beta

A solution prepared by dissolving 10g of 2-hydroxyethyl methacrylate, 40g of styrene, 40g of a methacrylic acid-modified siloxane (FM 0711, manufactured by チツソ Co.) and 2g of lauryl mercaptan in 200g of methyl ethyl ketone was heated in a reactor equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, and 0.6g of 2, 2' -azobis (2, 4-dimethylvaleronitrile) was added thereto at a temperature of 65 ℃ and 2 hours after the temperature reached 65 ℃ respectively, followed by a reaction at 65 ℃ for 5 hours to obtain a copolymer. Then, 22.2g of isophorone diisocyanate, 57.1g of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, was reacted at 25 ℃ for 3 hours, and while intermittently raising the temperature to 80 ℃ for 5 hours, 79.3g of an adduct was obtained, and this adduct 79.3g was added to the above-obtained copolymer and reacted at 80 ℃ for 5 hours to obtain a copolymer (siloxane compound β) having an acryloyl group and siloxane.

Siloxane compound gamma

A commercially available product of polyether-modified siloxane (SS-2803, manufactured by Japan ユニカ Co.) was used as it was.

(4) Pretreatment of the support

The weight per unit area used as a support was 125g/m²The neutral paper of (1) was coated with a silica-containing acrylic acid-based resin having the following composition by a bar coater as a coating material for a filler layer, and the thickness of the coating film after drying was set to 5g/m². After coating, the coating was dried at 110 ℃ for 1 minute.

[ acrylic resin ]

Styrene-acrylic emulsion

(X-436, manufactured by Star light Polymer Co.) 25 parts by weight

Water-soluble acrylic resin

(ヅヨンソソ Polymer company, PDX-6102) 25 parts by weight

Silicon dioxide

(サイシリア 350, manufactured by Fuji シリシア chemical Co., Ltd.) 10 parts by weight

25 parts by weight of isopropyl alcohol

25 parts by weight of water

(5) Preparation of coating liquid

Composition 1 was prepared by mixing 30 parts by weight of the ionizing radiation-curable composition a, 60 parts by weight of the film-forming resin b, and 10 parts by weight of the siloxane compound α (the parts by weight are all parts by weight of the solid content). A portion of the composition was sampled, the softening temperature was measured, and it was 76 ℃.

Compositions 2 to 9 were prepared by mixing the components at the mixing ratios (solid content parts by weight) shown in table 1 below in the same manner as described above. Silica (サイシリア 350, manufactured by fuji シリシア chemical company) was used as the inorganic pigment. A portion of the composition was sampled and the softening temperature was measured. The results are also shown in Table 1.

TABLE 1

(6) Production of release paper

With respect to the composition 1, 3 parts by weight of a photopolymerization initiator (イルガキユア 907, manufactured by チバスペシヤリテイ chemical company) and methyl ethyl ketone as a diluting solvent were added with respect to 100 parts by weight of solid content of the composition so that the solid content concentration became 30% by weight. Coating the obtained mixture on neutral paper without applying a gap layer by a bar coater to make the thickness of the coating film after drying about 5-10 g/m²And heating and evaporating at 110 deg.C for 1 min.

Thereafter, embossing is applied to the surface of the coating film. Embossing, in which a metal embossing roller having an uneven pattern is pressed against a paper roll having an uneven pattern as a backup roll.

The unevenness of a specific portion (3 mm. times.3 mm) of the emboss roller was measured by a three-dimensional surface roughness measuring machine (サ - フコム 590A, manufactured by Tokyo precision Co., Ltd.), and the center plane average roughness (Ra) was 12.99 μm and the ten-point average (Rz) was 65.78 μm.

At this time, the embossing roll temperature was set to 120 ℃ and the support and the dry coating film were simultaneously subjected to the embossing, and it was confirmed that the coating was favorably formed not only on the dry coating film surface but also on the back surface side of the support, and that the coating surface and the back surface side of the continuous paper were sufficiently formedThe concave-convex shape is formed. Next, using a high-pressure mercury lamp with an output of 120W/cm, 600mj/cm was conducted²The coating film is cured by ultraviolet irradiation to obtain release paper 1.

On the support (neutral paper having a filler layer or no filler layer) shown in table 2 below, each composition shown in the first column of table 2 was applied and dried in the same manner as described above. After drying, the respective compositions shown in the second column of Table 2 were applied and dried in the same manner. Thereafter, the embossing process was performed in the same manner as described above.

(7) Evaluation of

The obtained release papers 1 to 6 of examples and 7 to 9 of comparative examples were measured for embossing formability, heat resistance and releasability.

< emboss formability >

The unevenness of the embossed release paper corresponding to a specific portion of the embossing roller was measured by a three-dimensional surface roughness measuring instrument, and evaluated by the following criteria.

Very good: ra and Rz are both 85% or more of the value of the embossing roll

O: ra and Rz are both 70% or more of the value of the embossing roll, and one of them is 85% or more

And (delta): the value of Ra or Rz is 70% or more but less than 85% of the value of the embossing roll

X: the value of Ra and Rz is less than 70% of the value of the embossing roll

< production of PVC leather >

Coating 100g/m on the surface of the technical release paper by a bar coating machine²The vinyl chloride sol having the following composition was heated and cured at 220 ℃ for 3 minutes to form a leather sheet, and then peeled.

100 parts by weight of polyvinyl chloride (paste resin)

60 parts by weight of dioctyl phthalate

Blowing agent (azodicarbonamide) 3 parts by weight

Antioxidant (KF-80A-8, manufactured by Co., Ltd.) in 3 parts by weight

10 parts by weight of calcium carbonate

< Heat resistance >

The procedure of forming and peeling the leather sheet was repeated 5 times, and pattern running of the release paper and deterioration of the support were observed and evaluated according to the following criteria.

O: no abnormal shape at all until 5 th

And (delta): causing deformation and surface change, and cannot be used before 5 th time

X: can be used only 1 time due to molding deformation or breakage caused by support deterioration

< repeated Release Property >

The following single-component curing polyurethane was applied to the surface of a technical release paper by a bar coater and dried to 20g/m²Then, the mixture was dried by heating at 120 ℃ for 2 minutes.

[ one-component curing polyurethane ]

100 parts by weight of a main agent (CRISON, 7367SL, manufactured by Dainippon ink Co., Ltd.)

Colorant (DAILAC, TV-COLOR, manufactured by Dainippon ink Co., Ltd.) 15 parts by weight

30 parts by weight of solvent (methyl ethyl ketone)

Solvent (dimethylformamide) 10 parts by weight

Subsequently, a two-component curable urethane adhesive prepared as described below was applied by a bar coater and dried to give 20g/m²After the false deer skin is adhered thereon, the adhesive is cured by heating at 120 ℃ for 2 minutes and then cured at 50 ℃ for 24 hours to form a PU leather sheet.

[ two-pack curing type urethane adhesive ]

100 parts by weight of a base (CRISON, 4070, manufactured by DAJA INK CORPORATION)

50 parts by weight of a curing agent (CRISCON, NX, manufactured by Dainippon ink Co., Ltd.)

Accelerator (CRISVON, ACCEL, HM manufactured by Dainippon ink Co., Ltd.) 3 parts by weight

80 parts by weight of solvent (toluene)

40 parts by weight of solvent (ethyl acetate)

The obtained PU leather sheet was peeled from the release paper at a speed of 300 mm/min by 180 degrees using a tensile tester (テソシロソ RTC-1310A, manufactured by オリエソテツク Co.) to measure the peel strength. This was repeated 5 times, and the releasability was evaluated according to the following criteria.

Very good: the peel strength was less than 1N until the 5 th time, and the peelability was almost unchanged.

O: peeling was possible until 5 th time, but peeling was slightly deteriorated and peel strength was increased to 1N or more

And (delta): the releasability was rather deteriorated and became impossible to be peeled before the 5 th time

X: cannot be peeled off from the 1 st time

The results are shown in Table 2 below.

TABLE 2

As shown in the table above, the release papers 1 to 6 (examples 1 to 6) were excellent in all of embossing formability, heat resistance, and repeated releasability. On the other hand, in the release paper 7 (comparative example 1), the softening temperature of the coating material was low, and the emboss forming property was poor. In addition, in the release paper 8 (comparative example 2), embossing formability was poor. In addition, in the release paper 9 (comparative example 3), although the softening temperature of the coating material was high, the heat resistance was poor.

2.Synthetic leather obtained by the manufacturing method of the other embodiment of the present invention

Composition 10 was prepared by mixing 30 parts by weight of ionizing radiation-curable composition a, 60 parts by weight of film-forming resin b, and 10 parts by weight of silicone compound β (the parts by weight are all parts by weight of the solid content). A part of the composition was sampled and the softening temperature was measured to be 76 ℃.

Similarly to the above, 80 parts by weight of ionizing radiation-curable composition C, 10 parts by weight of film-forming resin b and 10 parts by weight of silicone compound α (the parts by weight are all parts by weight of solid matter) were mixed to prepare composition 11. A part of the composition was sampled and the softening temperature was measured to be 75 ℃.

< preparation of Release paper >

For the composition 10, 3 parts by weight of a photopolymerization initiator (チバスペシヤリテイ one chemical) was added per 100 parts by weight of the solid content of the compositionCompany product, イルガキユア 907), and methyl ethyl ketone was added as a diluting solvent so that the solid content concentration became 30% by weight. Coating the obtained mixture on neutral paper without applying a gap layer by a bar coater to a film thickness of about 5-10 g/m after drying²Coated and evaporated to dryness at 110 ℃ for 1 minute.

Next, 3 parts by weight of a photopolymerization initiator (イルガキユア 907, manufactured by チバスペシヤリテイ chemical company) and methyl ethyl ketone as a diluting solvent were added to 100 parts by weight of the solid content of the composition 11 so that the solid content concentration became 30% by weight. The resultant mixture was applied to the coating film made of the composition 10 in the same manner as described above, and then heated to evaporate and dry.

Thereafter, embossing is applied to the surface of the coating film. Embossing, in which a metal embossing roller having an uneven pattern is pressed against a paper roll having an uneven pattern as a backup roll.

At this time, the embossing roll temperature was set to 120 ℃, and embossing was simultaneously performed on the support and the dry coating film, and it was confirmed that not only the dry coating film surface but also the back surface side of the support was favorably formed, and that not only the coated surface but also the back surface of the paper was sufficiently formed with irregularities. Next, using a high-pressure mercury lamp with an output of 120W/cm, 600mj/cm was conducted²The coating film is cured by ultraviolet irradiation to obtain a release paper.

Example 7 (method for producing synthetic leather of first embodiment)

As the coating liquid for forming the skin layer, the following components were mixed and sufficiently stirred by a propeller mixer to prepare a mixture of the ester-based polyurethane resin composition.

< composition of ester-based polyurethane solution >

Ester-based polyurethane resin 100 parts by weight

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NB-637N)

Colorant 15 parts by weight

(ダイラツク TV-COLOR, manufactured by Dainippon ink chemical industry Co., Ltd.)

20 parts of methyl ethyl ketone

10 parts by weight of dimethylformamide

The prepared ester-based polyurethane resin was applied to the release paper obtained above with a blade coater so that the thickness was 20 μm, and the paper was hot-air dried at 100 ℃ for 2 minutes to form a polyurethane skin layer. Next, a two-component curable polyester urethane adhesive 1 having the following composition was applied to the urethane surface layer by a knife coater to have a dry thickness of 4 μm, and a knitted fabric was attached to the adhesive layer.

< composition of adhesive 1 >

100 parts by weight of main agent bi-component curing type ester polyurethane resin

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ 4070)

13 parts by weight of curing agent for curing polyurethane resin having two components

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NX)

3 parts by weight of curing accelerator for accelerator two-component curing type polyurethane resin

(クリスボソ ア ク セ ル HM manufactured by Dainippon ink chemical industry Co., Ltd.)

Solvent methyl ethyl ketone 30 parts by weight

The bonded product was dried with hot air at 100 ℃ for 5 minutes and then cured for 48 hours to react and cure the adhesive, and the release paper was peeled off to prepare a dry type PU synthetic leather.

Example 8 (method for producing synthetic leather of second form)

As the coating liquid for forming the skin layer, the following components were mixed and sufficiently stirred by a propeller mixer to prepare a mixture of the ester-based polyurethane resin composition.

< composition of ester-based polyurethane solution >

Ester-based polyurethane resin 100 parts by weight

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NB-637N)

Colorant 15 parts by weight

(ダイラツク TV-COLOR, manufactured by Dainippon ink chemical industry Co., Ltd.)

20 parts of methyl ethyl ketone

10 parts by weight of dimethylformamide

On the release paper obtained above, the prepared ester-based polyurethane solution was coated with a blade coater so that the drying thickness became 20 μm, and was hot-air dried at 100 ℃ for 2 minutes to form a polyurethane skin layer.

Next, a wet-type synthetic leather intermediate layer for forming the intermediate layer is prepared. As a resin for forming the wet synthetic leather intermediate layer, the following respective components were mixed and sufficiently stirred by a propeller mixer to prepare a mixture of an ester-based polyurethane resin composition.

< coating liquid for Forming intermediate layer of Wet synthetic leather >

100 parts by weight of a polyurethane resin

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NB-637N)

Colorant 1 part by weight

(グイラツク TV-COLOR, manufactured by Dainippon ink chemical industry Co., Ltd.)

160 parts by weight of film-making auxiliary agent

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ ア セ ス タ -SD-7)

10 parts by weight of dimethylformamide

On a base fabric formed of a tape-made small-loop multi-strand yarn (タム yarn) of 2.4 count 100% cotton, the above-mentioned coating liquid was applied with a blade coater so as to become 700g/m²Thereafter, the resulting solution was immersed in a coagulating solution (10% aqueous dimethylformamide) prepared at 30 ℃ for 5 minutes to form a film, and then washed with warm water at 60 ℃ for 15 minutes until the dimethylformamide was completely extracted. Thereafter, moisture was removed using mangrove (mangrove), and the wet synthetic leather intermediate layer was obtained by drying in an oven at 120 ℃.

Using a hot press at 180 ℃ under a pressure of 4kg/m²And under the condition of clamping and pressing, carrying out hot pressing on the obtained wet synthetic leather intermediate layer and the surface layer by using a hot roller. Subsequently, the wet polyurethane synthetic leather was produced by passing the wet polyurethane synthetic leather through a cooling roll and an air blowing area and then peeling off the release paper.

Example 9 (method for producing synthetic leather according to embodiment 3)

As the coating liquid for forming the skin layer, the following components were mixed and sufficiently stirred by a propeller mixer to prepare a mixture (sol-liquid mixture) of the polyvinyl chloride resin composition.

< PVC resin composition >

Emulsion polymerization polyvinyl chloride resin (average polymerization degree 1000)

(ZEST PX-QHP New first salt ビ Co., Ltd.) 20 parts by weight

Plasticizer dioctyl phthalate (DOT) 80 weight portions

Barium-zinc series composite stabilizer as stabilizer

(アデガスタプ LF-54, manufactured by Asahi Denka Co., Ltd.) 3 parts by weight

5 parts by weight of calcium carbonate as filler

Pigment titanium oxide 3 parts by weight

The above-mentioned sol mixture was applied to the above-obtained release paper by a doctor blade method so that the dry thickness became 300. mu.m, and hot air-dried at 150 ℃, 90 seconds and 195 ℃ for 3 minutes and 30 seconds to form a PVC skin layer.

Next, a knitted fabric was attached to the obtained PVC skin layer, and a release paper was peeled off to produce a PVC synthetic leather.

Example 10 (method for producing synthetic leather according to embodiment 4)

As the coating liquid for forming the skin layer, the following components were mixed and sufficiently stirred by a propeller mixer to prepare a mixture of the ester-based polyurethane resin composition.

< composition of ester-based polyurethane solution >

Ester-based polyurethane resin 100 parts by weight

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NB-637)

Colorant 15 parts by weight

(ダイラツク TV-COLOR, manufactured by Dainippon ink chemical industry Co., Ltd.)

20 parts of methyl ethyl ketone

10 parts by weight of dimethylformamide

On the release paper obtained above, the prepared ester-based polyurethane solution was coated with a blade coater so that the drying thickness became 20 μm, and hot air-dried at 100 ℃ for 2 minutes to form a polyurethane skin layer.

Next, the following components were mixed as a coating liquid for forming a foamed PVC layer, and sufficiently stirred by a propeller mixer to prepare a foamable PVC coating liquid.

< composition of foamable PVC coating liquid >

Emulsion polymerization polyvinyl chloride resin (resin obtained by copolymerizing epoxy group-containing monomers and having an average polymerization degree of 1500)

(ZEST PF-821 manufactured by NOVEL FIRST SALT ビ Co.) 20 parts by weight

Plasticizer dioctyl phthalate (DOT) 80 weight portions

Blowing agent azodicarbonamide (ADCA) 3 weight parts

Stabilizer barium-zinc series composite stabilizer 3 weight portions

(アデガスタプ LF-54, manufactured by Asahi Denka Co., Ltd.)

5 parts by weight of calcium carbonate as filler

Pigment titanium oxide 3 parts by weight

The above-mentioned foamable PVC coating liquid was applied to the polyurethane skin layer obtained above by a doctor blade method so that the dry thickness became 300. mu.m, and hot air-dried at 150 ℃, 90 seconds, 195 ℃, 3 minutes, and 30 seconds to form a foamed PVC layer.

Then, a knitted fabric was attached to the obtained foamed PVC layer, and a release paper was peeled off to produce a semi-synthetic leather.

< evaluation >

The same release paper was used as described above, and the synthetic leathers were produced by repeating 5 times, and pattern patterning of the release paper, deterioration of the support, and handling of the release paper were evaluated.

The pattern running of the release paper was evaluated according to the following criteria.

O: after 5 times of production, no pattern was formed by embossing

And (delta): the surface of the paper is embossed and shaped, or the surface of the release paper is changed, and the paper can not be used repeatedly for 5 times

X: the product can be used only 1 time, with deformation due to embossing or breakage due to support deterioration

Further, regarding the releasability of the release paper, a synthetic leather having a width of 15mm was peeled from the release paper at 180 ° at a speed of 300 mm/min using a tensile tester (テンシロソ RTC-1310A manufactured by オリエソテツク), and the peel strength was measured. Synthetic leathers were produced in the same manner as in the above examples by repeating 5 times using the same release paper, and the releasability when the synthetic leathers and the release paper were peeled was also measured.

Very good: after repeating this procedure for 5 times, the peel strength was less than 1N and the peelability was almost unchanged.

O: although the release paper can be used repeatedly 5 times, the releasability is slightly deteriorated and the peel strength is 1N or more

And (delta): when the release paper was used 5 times repeatedly, the releasability was considerably deteriorated and the release paper became impossible before the 5 th time.

X: the release paper could not be peeled from the 1 st time.

The results are shown in Table 3 below.

TABLE 3

3.Other forms of the embossed release paper of the present invention

Example 11

The resin to be the skin-like layer of the synthetic leather was prepared by mixing ester-based polyurethane solutions in a predetermined amount.

< composition of ester-based polyurethane solution >

Ester-based polyurethane resin 100 parts by weight

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NB-637N)

Colorant 15 parts by weight

(ダイラツク TV-COLOR, manufactured by Dainippon ink chemical industry Co., Ltd.)

20 parts of methyl ethyl ketone

10 parts by weight of dimethylformamide

On the release paper used in example 7, the formulated ester-based polyurethane solution was coated with a blade coater so that the drying thickness became 20 μm, and hot air-dried at 100 ℃ for 2 minutes to form a polyurethane skin layer. Next, a two-component curable polyester urethane adhesive 1 having the following composition was applied to the urethane surface layer by a knife coater to have a dry thickness of 40 μm, and a knitted fabric was attached to the adhesive layer.

< composition of adhesive 1 >

100 parts by weight of main agent bi-component curing type ester polyurethane resin

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ 4070)

13 parts by weight of curing agent for curing polyurethane resin having two components

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NX)

3 parts by weight of curing accelerator for accelerator two-component curing type polyurethane resin

(クリスボソ ア ク セ ル HM manufactured by Dainippon ink chemical industry Co., Ltd.)

Solvent methyl ethyl ketone 30 parts by weight

The laminate was dried with hot air at 100 ℃ for 5 minutes and then cured for 48 hours to react and cure the adhesive. Thereafter, in order to evaluate the suitability of the release paper obtained by repeated use, when the dry-type PU synthetic leather was produced by peeling the release paper from the release paper, the ratio of (1) the peel strength between the release paper and the synthetic leather, and (2) the siloxane existing on the surface of the release paper after peeling and the surface of the synthetic leather side were measured. Further, this operation was performed 5 times to confirm the change due to repeated use.

Example 12

Synthetic leather was produced and evaluated in the same manner as in example 11, except that the formulation of the adhesive 1 in example 11 was changed as follows.

< composition of adhesive 2 >

100 parts by weight of main agent bi-component curing type ester polyurethane resin

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ TA-265)

13 parts by weight of curing agent for curing polyurethane resin having two components

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NX)

3 parts by weight of curing accelerator for accelerator two-component curing type polyurethane resin

(クリスボソ ア ク セ ル HM manufactured by Dainippon ink chemical industry Co., Ltd.)

Solvent toluene/ethyl acetate (1/1) 25 parts by weight

Example 13

Synthetic leather was produced and evaluated in the same manner as in example 11, except that the formulation of the adhesive 1 in example 11 was changed as follows.

< composition of adhesive 3 >

100 parts by weight of main agent bi-component curing type ester polyurethane resin

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ TA-205)

13 parts by weight of curing agent for curing polyurethane resin having two components

(manufactured by Dainippon ink chemical industry Co., Ltd., クリスボソ NX)

3 parts by weight of curing accelerator for accelerator two-component curing type polyurethane resin

(クリスボソ ア ク セ ル HM manufactured by Dainippon ink chemical industry Co., Ltd.)

30 parts by weight of solvent toluene/ethyl acetate (1/1)

< repeated Release Property >

The releasability when the produced synthetic leather and the release paper were peeled from each other was measured by peeling the synthetic leather having a width of 15mm from the release paper at 180 ° at a speed of 300 mm/min using a tensile tester (テンシロソ RTC-1310A manufactured by オリエソテツク corporation), and measuring the peel strength. The same release paper was used to produce synthetic leather in the same manner as in the above examples, and the releasability when the synthetic leather and the release paper were peeled was also measured. The results are shown in Table 4 below.

TABLE 4

< proportion of silicon derived from siloxane present >

The ratio of silicon derived from siloxane in the release paper before the production of synthetic leather and the synthetic leather produced using the release paper as described above was measured. The measurement was performed as follows.

First, as a surface analyzer, an X-ray photoelectron spectroscopic analyzer (XPS, device name: ESCALB 220i-XL (manufactured by Thermo VG Scientific Co.) was used, and a release paper and a synthetic leather were cut into a square of 1cm at an arbitrary position, placed on a stage, and subjected to vacuum-pumping for pretreatment.

As the X-ray used, a non-monochromatic light Al — K α ray (output 300W) was used, and the X-ray was measured at a photoelectron incidence angle: the samples were set at 90 degrees, and silicon surface analysis was performed on each of the release paper and the synthetic leather to determine the amount of silicon derived from siloxane present on the surface. In addition, the treatment condition for measuring the background (background) of the result was carried out by the Shirley method. Further, similarly to the above, the same release paper was used, the production of synthetic leather was repeated similarly to the above examples, and the synthetic leather and the release paper were peeled off to measure the amount of silicon present in each. The results are shown in Table 5 below.

TABLE 5

4.Support body of the invention

Example 14

Comprises the following components in percentage by weight of L material 80%: to a pulp slurry of bleached kraft pulp in which an L material and an N material were mixed in an amount of 20% N material, 0.1% of an alkyl ketene dimer as a neutral filler was added based on the amount of the pulp. Using fourdriniersA short wire combined multi-cylinder machine, which made the slurry to a basis weight of 140g/m²The base paper of (1). Thereafter, in succession to the papermaking step, the paper was formed into a thickness of 9g/m on the base paper by an air knife coater²The base paper having a clay coating layer was produced by smoothing the clay coating layer with a calender roll.

The base paper having the clay coating layer prepared as described above was subjected to surface smoothness measurement by a measurement method based on JIS P8119 (using デヅタルペツク smoothness measuring machine manufactured by toyoyo seiki). Further, under the following conditions, tensile strength was measured by a test method in accordance with JIS P8113 (テンシロソ RTC-1310A manufactured by オリエソテツク) and tear strength was measured by a test method in accordance with JIS P8116 (エレメソドルフ tear tester manufactured by テスタ).

Condition (1): measurement conditions at Normal temperature (23 ℃ C., 50% RH)

Condition (2): after standing at 230 ℃ for 3 minutes (oven apparatus: MUFFLE FURANCEFP-31, ヤマト scientific Co., Ltd.)

The results are shown in Table 6 below.

From the results of Table 6, it is understood that the smoothness was 153.8 seconds, and that the tensile strength (kN/m) in the machine direction was 13.4kN/m, the tear strength (mN) was 627mN in the machine direction, 627mN in the transverse direction, and 500mN or more in both the machine direction and the transverse direction, with respect to the tensile strength and the tear strength, even under the condition (2).

The base paper having the clay coating layer prepared as described above was coated with a coating solution to prepare a coated base. The coating liquid used was: an ultraviolet-curable resin (composition 1 used in example 1 above) was added with a reaction initiator (イルガキユア 907, manufactured by チパスペシヤリテイ chemical company) in an amount of 3% by weight based on the solid content of the resin, and the mixture was dissolved in methyl ethyl ketone to obtain a coating solution. Using reverse coater on clayThe coating liquid was applied on the coating layer so that the weight of the coating liquid after evaporation and drying of the solvent became 10g/m²The solvent was evaporated and dried to prepare a coated substrate having an ultraviolet curable resin layer.

The coated substrate was passed through a mirror-finished calender roll, and the mirror surface of the calender roll was transferred to the surface of the ultraviolet-curable resin layer to examine transferability. Specifically, the surface of a calender roll at 110 ℃ was brought into contact with the ultraviolet-curable resin surface of the coated substrate, and a line pressure of 100kN/m was applied between the platen and the calender roll to transfer the ultraviolet-curable resin, and thereafter, a high-pressure mercury lamp (output 120W/cm) was used to perform transfer at 600mJ/cm on the transfer surface²The ultraviolet curable resin is cured by the ultraviolet irradiation of (1).

The evaluation substrate thus obtained was measured for 60 ° specular gloss (Gs (60 °)) on the transfer surface using a digital variable angle gloss meter (スガ test machine), and the transferability was evaluated.

The results are shown in Table 7 below. From the results in Table 7, it is understood that Gs (60 ℃ C.) is 74%, and that the transferability is good. The transferability was evaluated by the following criteria.

Gs (60 degree) is more than or equal to 80%: particularly good (verycircus)

80% is more than Gs (60 degree) is more than or equal to 70%: good (∘)

70% > Gs (60 degree) is more than or equal to 60%: difference (Delta)

60% > Gs (60 °): it was particularly poor and could not be used (X)

Further, a production test of polyvinyl chloride synthetic leather was repeatedly performed using the above evaluation substrate, and the number of times of use under the same substrate was examined to evaluate heat resistance. The evaluation criteria are as follows.

The substrate was evaluated not to break, and 5 or more times of substrates were used: good Heat resistance (. smallcircle.)

The substrate was evaluated for fracture less than 5 times: poor Heat resistance (X)

The results are shown in table 7. From the results, it was found that the evaluation substrate was a substrate having good heat resistance that can withstand use 5 times or more.

Example 15

Comprises the following components in percentage by weight of L material 80%: to a pulp slurry of bleached kraft pulp in which an L material and an N material were mixed in an amount of 20% N material, 0.1% of an alkyl ketene dimer as a neutral filler was added based on the amount of the pulp. The slurry was made into a sheet having a basis weight of 140g/m by using a fourdrinier and fourdrinier combined papermaking machine²The base paper of (1). Thereafter, in succession to the papermaking step, the raw paper was formed into a sheet of 18g/m by a blade coater and an air knife coater²The base paper having a clay coating layer was produced by smoothing the clay coating layer with a calender roll.

The base paper having a clay coating layer prepared as described above was evaluated in the same manner as in example 14.

The results are shown in Table 6. From the results of Table 6, it is understood that the smoothness was 462.3 seconds, and that the tensile strength (kN/m) in the machine direction was 12.8kN/m, the tear strength (mN) was 638mN in the machine direction, 578mN in the transverse direction and 500mN or more in both the machine direction and the transverse direction, with respect to the tensile strength and the tear strength, even under the condition (2).

An evaluation substrate was formed in the same manner as in example 14 using the base paper having the clay coating layer prepared in the above manner.

The obtained evaluation substrate was measured for 60 ° specular gloss (Gs (60 °)) on the transfer surface and evaluated for transferability and heat resistance in the same manner as in example 14.

The results are shown in Table 7. From the results in Table 7, it is understood that Gs (60 ℃ C.) is 83%, and that transferability is good. In addition, the evaluation substrate is a substrate having good heat resistance that can withstand use 5 times or more.

Comparative example 4

Comprises the following components in percentage by weight of L material 80%: mixing N material 20%In a pulp slurry of bleached kraft pulp of L-material and N-material, 0.1% of alkyl ketene dimer as a neutral filler was added based on the amount of the pulp. The slurry was made into a sheet having a basis weight of 140g/m by using a fourdrinier and fourdrinier combined papermaking machine²The base paper of (2) was prepared without clay coating.

The base paper without clay coating prepared as described above was subjected to the measurements of surface smoothness, tensile strength and tear strength in the same manner as in example 14.

The results are shown in Table 6. From the results of Table 6, it is understood that the smoothness was low at 77.2 seconds, and the tensile strength and tear strength were 10kN/m or more even under the condition (2) with the tensile strength (kN/m) in the machine direction of 14.0kN/m, the tear strength (mN) was 655mN in the machine direction, 605mN in the transverse direction, and 500mN or more in both the machine direction and the transverse direction.

An evaluation substrate was formed in the same manner as in example 14 using the base paper without the clay coating prepared as described above.

The obtained evaluation substrate was measured for 60 ° specular gloss (Gs (60 °)) on the transfer surface and evaluated for transferability and heat resistance in the same manner as in example 14.

The results are shown in Table 7. From the results in Table 7, it is understood that Gs (60 ℃ C.) is low, 52%, and transferability is particularly poor, and thus it cannot be used.

Comparative example 5

Comprises the following components in percentage by weight of L material 80%: to a pulp slurry of bleached kraft pulp in which 20% of N material was mixed with L material and N material, aluminum sulfate was added as a rosin-based filler and a fixing agent. The slurry was made into a sheet having a basis weight of 140g/m by using a fourdrinier and fourdrinier combined papermaking machine²The base paper of (1). Thereafter, in succession to the papermaking step, the paper was formed into a thickness of 9g/m on the base paper by an air knife coater²The base paper having a clay coating layer was produced by smoothing the clay coating layer with a calender roll.

The base paper having the clay coating layer prepared as described above was evaluated in the same manner as in example 14.

The results are shown in Table 6. From the results of Table 6, it is understood that the smoothness was low at 77.2 seconds, and regarding the tensile strength and tear strength, under the condition (2), the tensile strength (kN/m) in the machine direction was 4.2kN/m and less than 10kN/m, and the tear strength (mN) was 158mN in the machine direction and 125mN in the transverse direction, and less than 500mN in both the machine direction and the transverse direction.

An evaluation substrate was formed in the same manner as in example 14 using the base paper having the clay coating layer prepared as described above.

The obtained evaluation substrate was measured for 60 ° specular gloss (Gs (60 °)) on the transfer surface and evaluated for transferability and heat resistance in the same manner as in example 14.

The results are shown in Table 7. From the results shown in Table 7, it is understood that Gs (60 ℃ C.) is as high as 63% and that the transferability is good, but the fracture is caused in the 2 nd transfer, and the heat resistance is not good, and the practical value is low.

TABLE 6

TABLE 7

Claims (31)

1. An embossed release paper for producing synthetic leather, comprising at least paper as a support and an ionizing radiation curing film provided on the paper, wherein the film is formed by applying an embossing process to the curing film, and wherein the ionizing radiation curing film is a film obtained by curing a coating solution by irradiation with ionizing radiation, the coating solution is a composition curable by ionizing radiation having at least a softening point of 40 ℃ or higher, the curable composition contains a reaction product of an isocyanate compound and a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, or contains an isocyanate compound, a (meth) acryloyl compound having a (meth) acryloyl group and being capable of reacting with the isocyanate compound, and a (meth) acryloyl compound having no (meth) acryloyl group and being capable of reacting with the isocyanate compound A reaction product formed from a compound having an ester group reacted therewith.

2. The embossed release paper according to claim 1, wherein the ionizing radiation curing film further contains 1 to 70% by weight of a film-forming resin.

3. The embossed release paper according to claim 1, wherein the ionizing radiation curing film further contains 0.5 to 20% by weight of a silicone compound.

4. The embossed release paper according to claim 1, wherein an interstitial layer containing an inorganic pigment and a film-forming resin is applied to the surface of the support.

5. The embossed release paper according to claim 1, wherein the ionizing radiation curing film has a structure of at least two layers.

6. The embossed release paper according to claim 5, wherein at least one of the ionizing radiation curing films having a two-layer or more structure contains 0.5 to 50% by weight of an inorganic pigment.

7. The embossed release paper according to claim 5 or 6, wherein the ionizing radiation curing film having a structure of two or more layers contains 0.5 to 50 wt% of an inorganic pigment in a lowermost layer disposed on the support side.

8. The embossed release paper according to claim 5 or 6, wherein at least one of the ionizing radiation-cured films having a two-layer or more structure contains 0.5 to 20% by weight of a siloxane compound.

9. The embossed release paper according to claim 5 or 6, wherein the ionizing radiation-cured film having a structure of two or more layers contains 0.5 to 20% by weight of a siloxane compound in an uppermost layer disposed on a side opposite to a support.

10. The embossed release paper according to claim 5 or 6, wherein the ionizing radiation curing film has a two-layer or more structure, and the inorganic pigment is contained in an amount of 0.5 to 50 wt% in a lowermost layer disposed on the support side, and the silicone compound is contained in an amount of 0.5 to 20 wt% in an uppermost layer disposed on the side opposite to the support side.

11. The embossed release paper according to claim 5 or 6, wherein the ionizing radiation curing film having a structure of two or more layers contains 0.5 to 50 wt% of an inorganic pigment in the lowermost layer disposed on the support side, and 0.5 to 20 wt% of a silicone compound in each layer.

12. The embossed release paper according to claim 1, wherein the paper as the support is neutral paper.

13. The embossed release paper according to claim 1, which is formed by embossing a paper as a support.

14. The embossed release paper according to claim 3, wherein the proportion of silicon derived from siloxane present on the surface of the ionizing radiation curing film is 5 to 30%, and the proportion of silicon derived from siloxane present on the surface of the ionizing radiation curing film is 5% or more when the step of producing synthetic leather using the release paper is repeated 5 times.

15. A method of manufacturing the embossed release paper of claim 1, characterized by comprising: coating the surface of the support with a coating liquid so that the coating weight after drying is 1-40 g/m²A step for forming a coating film; evaporating and drying the solvent of the coating film; embossing the dried coating film or simultaneously embossing the support and the dried coating film; a step of irradiating the coating film with ionizing radiation to form an ionizing radiation cured film,

the coating liquid is formed by at least an ionizing radiation curable composition having a softening point of 40 ℃ or higher, the curable composition containing a reaction product formed by an isocyanate compound and a (meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with the isocyanate compound, or a reaction product formed by an isocyanate compound, a (meth) acryloyl compound having a (meth) acryloyl group and capable of reacting with the isocyanate compound, and a compound having no (meth) acryloyl group and capable of reacting with an isocyanate group, the coating liquid being obtained by diluting with 10 to 1000 parts by weight of a solvent with respect to 100 parts by weight of solid content in the coating liquid.

16. A method of manufacturing synthetic leather using the embossed release paper of claim 1, characterized by comprising: a step of applying a polyurethane resin composition to the embossed ionizing radiation curable film, and heating and drying the composition to form a skin layer; a step of forming a synthetic leather layer by bonding a base fabric to the surface layer with an adhesive; and a step of peeling the release paper from the synthetic leather layer.

17. The method of claim 16, wherein said adhesive is a two-part curable polyurethane resin.

18. The method according to claim 16, wherein said step of bonding said base fabric comprises applying an adhesive to said skin-like layer, drying said adhesive, and bonding said base fabric to said adhesive by heat lamination.

19. A method of manufacturing synthetic leather using the embossed release paper of claim 1, characterized by comprising: a step of applying a polyurethane resin composition to the embossed ionizing radiation curable film, and heating and drying the composition to form a skin layer; laminating a wet intermediate layer on the surface layer, and laminating the surface layer and the wet intermediate layer from the release paper side by a heat roll to form a synthetic leather layer; and a step of cooling the synthetic leather layer and then peeling the release paper.

20. A method of manufacturing synthetic leather using the embossed release paper of claim 1, characterized by comprising: a step of applying a vinyl chloride resin composition to the embossed ionizing radiation curable film, and heating and drying the resultant to form a skin layer; a step of applying a foamable vinyl chloride resin composition to the skin layer and heating the composition to form an intermediate layer; a step of bonding a base fabric to the intermediate layer with an adhesive agent to form a synthetic leather layer; and a step of peeling the release paper from the synthetic leather layer.

21. A method of manufacturing synthetic leather using the embossed release paper of claim 1, comprising: a step of applying a polyurethane resin composition to the embossed ionizing radiation curable film, and heating and drying the composition to form a skin layer; a step of applying a foamable vinyl chloride resin composition to the skin layer and heating the composition to form an intermediate layer; a step of bonding a base fabric to the intermediate layer with an adhesive agent to form a synthetic leather layer; and a step of peeling the release paper from the synthetic leather layer.

22. A synthetic leather produced by using the embossed release paper according to claim 14, wherein the synthetic leather obtained by peeling the release paper has a silicone-derived silicon content of 20% or less on the peeled surface.

23. The synthetic leather of claim 22, said release paper being a multi-use release paper.

24. A synthetic leather obtained by the method according to any one of claims 17 to 21.

25. A support used for the embossed release paper for synthetic leather production according to claim 1, which comprises a base paper having a clay coating layer on one side thereof, wherein the base paper has a tensile strength measured by a measurement method based on JIS P8113 standard after being left at 230 ℃ for 3 minutes, and is maintained at 10kN/m or more at least in the longitudinal direction, and a tear strength measured by a measurement method based on JIS P8116 standard after being left at 230 ℃ for 3 minutes, and is maintained at a heat resistance of 500mN or more in both the longitudinal and transverse directions, and the clay coating layer has a smoothness of 100 seconds or more measured by a measurement method based on JIS P8119 standard, and surface irregularities due to pulp fibers of the base paper are absorbed.

26. The support according to claim 25, wherein the base paper is a base paper obtained by papermaking using a mixed pulp of hardwood pulp and softwood pulp, and the mixed pulp contains 50 to 90% of hardwood pulp.

27. The support of claim 25 or 26 wherein said base paper is neutral paper sized with an alkyl ketene dimer.

28. The support body according to claim 25 or 26, wherein the base paper has a thickness of 100 to 200g/m²Weight per unit area of (c).

29. The support according to claim 25 or 26, said clay coating having a thickness of 5 to 40g/m²The coating amount of (3).

30. A method for manufacturing a release paper using the support for the embossed release paper for synthetic leather manufacturing of claim 25, characterized by comprising: a step of providing an uncured ionizing radiation curable resin film on the clay coating layer of the support; a step of embossing the uncured ionizing radiation curable resin film; and a step of irradiating the ionizing radiation-curable resin film with ionizing radiation to cure the resin film after the embossing step.

31. An embossed release paper for synthetic leather production produced by the method of claim 30.