HK1211544B

HK1211544B - Mold release film and production method for same

Info

Publication number: HK1211544B
Application number: HK15112300.3A
Authority: HK
Inventors: 荒木悟郎; 奥村畅康; 上野嘉己
Original assignee: 尤尼吉可株式会社
Priority date: 2013-01-11
Filing date: 2014-01-09
Publication date: 2018-05-11

Description

Mold release film and method for producing same

Technical Field

The present invention relates to a release film suitable as a release material.

Background

Polyester films represented by polyethylene terephthalate are widely used in industrial fields and industrial fields because of their excellent mechanical properties, heat resistance, and chemical resistance. Among them, the demand for engineering materials has been remarkably increasing in recent years, and particularly, a mold release material, which is one of the engineering materials, is widely used in the field of electronics and motors. Examples of applications of the release material include adhesive surface protective materials for adhesive materials such as adhesive sheets and adhesive tapes.

As a release material having a resin layer with releasability provided on a polyester film surface, for example, patent document 1 discloses a release sheet in which a resin layer containing a polypropylene-based modified polyolefin resin is provided on a polyester film by post coating (post coat). However, when an adhesive material having a high peel strength is applied to a resin layer provided by post-application, the components of the resin layer may migrate to the adhesive material, and therefore, there is a problem that the re-adhesiveness of the peeled adhesive material is lowered, the residual adhesion rate is lowered, and the performance as an adhesive material is impaired.

Patent documents 2 and 3 disclose release films in which a resin layer containing a polyethylene-based modified polyolefin resin is provided on a polyester film by in-line coating. However, since the resin layer containing the polyethylene-based modified polyolefin resin has a low peel strength, if the resin layer to which the adhesive is applied is subjected to punching, the end portion is lifted, and the punching cannot be performed perfectly.

In addition, when the release film described in patent documents 1 to 3, in which a resin layer is provided on one surface of a polyester film, is wound into a roll shape, depending on the composition of the resin layer, the components of the resin layer may migrate to the opposite surface of the surface on which the resin layer is provided, and the opposite surface may be contaminated.

Documents of the prior art

Patent document

Patent document 1, Japanese patent application laid-open No. 2011-

Patent document 2, Japanese patent laid-open No. 2012-20429

Patent document 3 Japanese laid-open patent publication No. 2012-144021

Disclosure of Invention

In view of these problems, an object of the present invention is to provide a release film suitable as a release material, which is capable of preventing a resin layer component from easily migrating to an adhesive material even if the peel strength between the resin layer and the adhesive material is high, maintaining a high residual adhesion rate of the peeled adhesive material, and preventing contamination of the surface opposite to the surface on which the resin layer is provided even when the release film is wound into a roll.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by including a step of applying a liquid material for forming a resin layer on a polyester film, and drying, stretching and heat-treating the polyester film applied with the liquid material, and have completed the present invention.

That is, the gist of the present invention is the following (1) to (5).

(1) A mold release film characterized in that a resin layer is provided on one surface of a polyester film,

the resin layer contains 100 parts by mass of a polypropylene-based modified polyolefin resin having a modifying component content of 1 to 10% by mass and 1 to 50 parts by mass of a crosslinking agent,

the peel strength between the resin layer and the adhesive is more than 3.0N/cm when the rubber adhesive is attached to the resin layer,

the residual adhesion ratio of the adhesive after the acrylic adhesive is adhered to the resin layer is 80% or more.

(2) The release film according to the item (1), wherein the resin layer further contains polyvinyl alcohol, and the content of polyvinyl alcohol is 10 to 1000 parts by mass per 100 parts by mass of the polypropylene-based modified polyolefin resin.

(3) The release film according to (1) or (2), wherein a contact angle of water on a surface opposite to the surface provided with the resin layer is 80 ° or less.

(4) The release film according to any one of items 1 to 3, wherein the polyester film has a multilayer structure in which 2 or more layers are laminated.

(5) A process for producing the release film according to the above (1), which comprises a step of coating a polyester film with a liquid material containing 100 parts by mass of a polypropylene-based modified polyolefin resin having a modifying component content of 1 to 10% by mass, 1 to 50 parts by mass of a crosslinking agent, and a liquid medium, and a step of drying, stretching, and heat-treating the polyester film coated with the liquid material.

The release film of the present invention is suitable for use in applications such as an adhesive surface protective material for an adhesive material such as an adhesive sheet and an adhesive tape, because the resin layer component is less likely to migrate to the adhesive material and the residual adhesion rate of the peeled adhesive material can be kept high even if the peel strength between the resin layer and the adhesive material is high. In addition, even if the release film of the present invention is wound into a roll shape, the surface opposite to the surface provided with the resin layer is not contaminated with the resin layer.

Detailed Description

The present invention will be described in detail below.

The release film of the present invention is a release film having a resin layer on one surface of a polyester film, the resin layer containing a polypropylene-based modified polyolefin resin and a crosslinking agent.

The polypropylene-based modified polyolefin resin used in the present invention is required to be a polypropylene-based resin in which propylene is the main component of the olefin component. By using propylene as the main component of the olefin component, the peel strength between the resin layer and the adhesive can be made to exceed 3.0N/cm when the obtained resin layer is attached to a rubber adhesive for measurement. The olefin component preferably further contains butene and ethylene from the viewpoint of improving film formability.

Examples of the modifying component constituting the polypropylene-based modified polyolefin resin include unsaturated carboxylic acid components, specifically, half esters and half amides of unsaturated dicarboxylic acids in addition to acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, and the like. Among them, in the aqueous dispersion of the resin described later, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable, and acrylic acid, methacrylic acid, and maleic anhydride are particularly preferable, in order to stably disperse the resin. These modifying components may be contained in the polypropylene-based modified polyolefin resin in an amount of 2 or more.

The proportion of the modifying component in the polypropylene-based modified polyolefin resin is desirably 1 to 10% by mass, more preferably 2 to 10% by mass, and particularly preferably 2 to 9% by mass. If the proportion of the modifying component is less than 1% by mass, the proportion of the polar group in the polypropylene-based modified polyolefin resin contained in the resin layer is reduced, and therefore sufficient adhesion to the polyester film may not be obtained, and the adhesive material may be contaminated. In addition, in the aqueous dispersion of a resin described later, it tends to be difficult to stably disperse the resin. On the other hand, when the proportion of the modifying component exceeds 10 mass%, the proportion of the polar group increases, so that the adhesion between the resin layer and the polyester film becomes sufficient, but the adhesion between the resin layer and the adhesive material also increases, so that the releasability from the adhesive material tends to decrease.

The polypropylene-based modified polyolefin resin may contain, in addition to the above components, other components in an amount of about 10% by mass or less of the entire polyolefin resin. Examples of the other components include (meth) acrylates such as 1-octene, ethyl (meth) acrylate, and butyl (meth) acrylate; (meth) acrylamides; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl pivalate, and vinyl versatate, and vinyl alcohols obtained by saponifying vinyl esters with an alkaline compound or the like; 2-hydroxyethyl acrylate; glycidyl (meth) acrylate; (meth) acrylonitrile; styrene; substituted styrenes; halogenated ethylenes; vinyl halides; vinylidene halides; carbon monoxide; sulfur dioxide, and the like. Mixtures thereof may also be used.

The copolymerization form of each component in the polypropylene-based modified polyolefin resin is not limited, and examples thereof include random copolymerization, block copolymerization and the like. Among them, random copolymerization is preferable from the viewpoint of easy polymerization. In addition, 2 or more kinds of polyolefin resins may be mixed so as to be a ratio of the constituent components of the present invention.

The polypropylene-based modified polyolefin resin is preferably obtained by introducing the above-mentioned unsaturated carboxylic acid component as a modifying component into a polypropylene-based resin, and the method is not particularly limited. For example, there may be mentioned a method of graft-copolymerizing an unsaturated carboxylic acid component onto a polypropylene resin, such as a method of heating and melting the polypropylene resin and the unsaturated carboxylic acid to a temperature not lower than the melting point of the propylene resin in the presence of a radical generator to cause a reaction, or a method of dissolving the polypropylene resin and the unsaturated carboxylic acid in an organic solvent and then heating and stirring the solution in the presence of a radical generator to cause a reaction. The former method is preferable from the viewpoint of ease of operation.

Examples of the radical generator used in the graft copolymerization include organic peroxides such as di-t-butyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, t-butylcumyl peroxide, benzoyl peroxide, dilauroyl peroxide, cumyl peroxide, t-butyl peroxybenzoate, methyl ethyl ketone peroxide, di-t-butyl diperoxyphthalate, and azonitriles such as azobisisobutyronitrile. They may be appropriately selected and used depending on the reaction temperature.

In the present invention, the resin layer is required to contain both the polypropylene-based modified polyolefin resin and the crosslinking agent. By containing the crosslinking agent, the constituent components of the resin layer are crosslinked, and various properties such as cohesive force and water resistance of the resin layer can be improved.

The amount of the crosslinking agent to be added is 1 to 50 parts by mass, preferably 2 to 40 parts by mass, and more preferably 2 to 30 parts by mass, per 100 parts by mass of the polypropylene-based modified polyolefin resin.

As the crosslinking agent, a crosslinking agent which crosslinks the modified polyolefin and the polyvinyl alcohol, a compound having a plurality of functional groups which react with carboxyl groups in the molecule, and the like can be used, and among them, an isocyanate compound, a melamine compound, a urea compound, an epoxy compound, a carbodiimide compound, a carboxyl group-containing compound, and the like are preferable,Oxazoline compounds, etc., particularly carbodiimide compounds,Oxazoline compounds are effective. These crosslinking agents may be used in combination.

The carbodiimide compound used as the crosslinking agent is not particularly limited as long as it has 1 or more carbodiimide groups in the molecule. The carbodiimide compound 1 has a carbodiimide moiety crosslinked with 2 carboxyl groups of a modified moiety of the polypropylene-based modified polyolefin resin.

Specific examples of the carbodiimide compound include compounds having a carbodiimide group such as p-phenylenebis (2, 6-xylylcarbodiimide), tetramethylenebis (t-butylcarbodiimide), and cyclohexane-1, 4-bis (methylene-t-butylcarbodiimide), and polycarbodiimides which are polymers having a carbodiimide group. 1 or 2 or more of them may be used. Among them, polycarbodiimide is preferable from the viewpoint of easy handling.

Commercially available products of polycarbodiimide include CARBODILITE series available from Nisshinbo Co., Ltd, and specifically include water-soluble types "SV-02", "V-02-L2", "V-04"; emulsion type "E-01", "E-02"; "V-01", "V-03", "V-07", "V-09" of the organic solution type; "V-05" of the solvent-free type.

Used as cross-linking agentOxazoline formationProvided that the compound has 2 or more atoms in the moleculeThe oxazoline group is not particularly limited.2 oxazoline compoundsThe oxazoline moiety and 1 carboxyl group of the modified moiety of the polypropylene-based modified polyolefin resin form amide esters, respectively, to effect crosslinking.

AsSpecific examples of the oxazoline compound include, for example, 2' -bis (2-)Oxazoline), 2 '-ethylene-bis (4, 4' -dimethyl-2-Oxazoline), 2' -p-phenylene-bis (2-Oxazoline), bis (2-Oxazoline-based cyclohexane) sulfides, etc. havingOxazoline-based compounds containingAn oxazoline-based polymer. 1 or 2 or more of them may be used. Among them, from the viewpoint of easy handling, it preferably containsAn oxazoline-based polymer.

As containingAs commercially available oxazoline-based polymers, there are exemplified EPOCROS series available from Japanese catalyst corporation, and specifically, water-soluble type "WS-500", "WS-700"; emulsion types "K-1010E", "K-1020E", "K-1030E", "K-2010E", "K-2020E", "K-2030E", and the like.

In the present invention, the resin layer preferably contains polyvinyl alcohol. By dispersing polyvinyl alcohol in the polypropylene modified polyolefin resin in the resin layer, the releasability of the polypropylene modified polyolefin resin can be reduced appropriately, and the effect of improving the adhesion of polyvinyl alcohol itself to the polyester film can be achieved. In addition, since the resin layer contains the crosslinking agent and the polyvinyl alcohol, minute protrusions are formed on the surface of the resin layer, and therefore, the slipperiness of the resin layer is remarkably improved.

The kind of polyvinyl alcohol is not particularly limited, and examples thereof include polyvinyl alcohols obtained by completely or partially saponifying a polymer of a vinyl ester.

When used as a liquid as described below, the polyvinyl alcohol is preferably water-soluble.

The average polymerization degree of the polyvinyl alcohol is not particularly limited, and for example, a polyvinyl alcohol having an average polymerization degree of 300 to 5000 can be used, and from the viewpoint of improving the stability of the liquid for forming the resin layer, 300 to 2000 is preferable.

When the polyvinyl alcohol is contained, the content thereof is preferably 10 to 1000 parts by mass, more preferably 10 to 600 parts by mass, still more preferably 20 to 400 parts by mass, and most preferably 30 to 300 parts by mass, based on 100 parts by mass of the polypropylene-based modified polyolefin resin. When the content of the polyvinyl alcohol is in this range, the influence of heating such as drying and heat treatment on the releasability of the resin layer when forming the resin layer on the polyester film can be further reduced.

Examples of commercially available polyvinyl alcohols include "JC-05", "VC-10", "ASC-05X" and "UMR-10 HH" of "J-POVAL" manufactured by Japan Vam & Poval; "PVA-103", "PVA-105" of "KURAAYYPOVAL" manufactured by KURARAAY corporation, "AQ 4104" and "HR 3010" of "PVA-105" and "EXCEVAL"; "PC-1000" and "PC-2000" of "DENKAPOVAL" manufactured by electrochemical industries, Ltd.

In the present invention, the resin layer may contain a lubricant within a range not to impair the effects of the present invention. Examples of the lubricant include inorganic particles such as calcium carbonate, magnesium carbonate, calcium oxide, zinc oxide, magnesium oxide, silicon oxide, sodium silicate, aluminum hydroxide, iron oxide, zirconium oxide, barium sulfate, titanium oxide, tin oxide, antimony trioxide, carbon black, and molybdenum disulfide, and organic particles such as acrylic crosslinked polymer, styrene crosslinked polymer, silicone resin, fluorine resin, benzoguanamine resin, phenol resin, nylon resin, and polyethylene wax.

In the release film of the present invention, the resin layer contains 100 parts by mass of a polypropylene-based modified polyolefin resin and 1 to 50 parts by mass of a crosslinking agent in a proportion of 1 to 10% by mass of a modifying component, and therefore the peel strength between the resin layer and the adhesive can exceed 3.0N/cm, preferably 3.0 to 5.5N/cm, more preferably 3.5 to 5.0N/cm when measured by attaching a rubber-based adhesive as an adhesive material to the resin layer. When the peel strength is 3.0N/cm or less, sufficient adhesion between the resin layer and the adhesive cannot be obtained, and the resin layer and the adhesive may peel off in the steps of storage, cutting, and conveyance.

In addition, since the resin layer component is less likely to migrate to the pressure-sensitive adhesive material, the release film of the present invention is less likely to cause a decrease in the peel strength of the pressure-sensitive adhesive after the acrylic pressure-sensitive adhesive as the pressure-sensitive adhesive material is attached to the resin layer, and can have a residual adhesion rate of 80% or more, preferably 82% or more, and more preferably 85% or more.

When the surface of an acrylic pressure-sensitive adhesive as a pressure-sensitive adhesive is contaminated with a resin layer of a release film, the re-adhesiveness of the pressure-sensitive adhesive is lowered, and the performance as a pressure-sensitive adhesive is impaired. Therefore, the higher the residual adhesion rate, the better.

In the release film of the present invention, the resin layer component is less likely to migrate to materials other than the adhesive material, and even when the release film is wound into a roll shape, the opposite surface to the surface provided with the resin layer is not contaminated with the resin layer. If the surface opposite to the surface provided with the resin layer is contaminated with the resin layer, the contact angle of the surface is increased. That is, the contact angle of water on the surface of the base polyester film is 60 to 70 DEG, while the contact angle of the surface of the resin layer is 90 to 100 DEG, and if the surface opposite to the surface provided with the resin layer is contaminated with the resin layer, the contact angle of the surface is increased from 60 to 70 DEG and approaches 90 to 100 deg. In the present invention, since the resin layer is not contaminated, even when the release film is rolled up in a roll form, the contact angle of water on the surface opposite to the surface on which the resin layer is provided can be set to 80 ° or less. If the contact angle of the opposite surface is 80 ° or less, it is considered that the opposite surface of the film is not contaminated, and the contact angle is preferably 75 ° or less. If the contact angle exceeds 80 deg., the opposite side of the film may be contaminated and the process may be contaminated.

In the present invention, the thickness of the resin layer is preferably in the range of 0.01 to 1 μm, more preferably 0.03 to 0.7 μm, and still more preferably 0.05 to 0.5. mu.m. When the thickness is less than 0.01. mu.m, sufficient releasability cannot be obtained, and when the thickness exceeds 1 μm, releasability is saturated, which may not be improved and residual adhesion may be lowered.

In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

Preferable specific examples of the polyester include polyesters such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1, 4-cyclohexylenedimethylene terephthalate) and polyethylene 2, 6-naphthalate, and copolymers thereof.

The acid component includes, but is not particularly limited to, isophthalic acid, phthalic acid, 2, 6-naphthalenedicarboxylic acid, isophthalic acid-5-sodium sulfonate, oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, cyclohexane dicarboxylic acid, and other dicarboxylic acids, 4-hydroxybenzoic acid, -caprolactone, and lactic acid.

Examples of the alcohol component include ethylene glycol, diethylene glycol, 1, 3-propanediol, neopentyl glycol, 1, 6-hexanediol, cyclohexanedimethanol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol a, and ethylene oxide adducts of bisphenol S.

In addition, a small amount of a 3-functional compound such as trimellitic acid, 1,3, 5-trimellitic acid, pyromellitic acid, trimethylolpropane, glycerol, pentaerythritol, or the like can be used.

These copolymerization components may be used in combination of 2 or more. In addition, can also be mixed with 2 or more kinds of polyester use.

In the present invention, polyethylene terephthalate and polyethylene-2, 6-naphthalate are particularly preferable as the polyester.

The intrinsic viscosity of the polyester is preferably 0.55 to 0.80, more preferably 0.60 to 0.75. If the intrinsic viscosity is less than the above range, the film is likely to be broken during film formation, stable production is difficult, and the strength of the obtained film is low. On the other hand, when the intrinsic viscosity exceeds the above range, shear heat generation increases during melt extrusion of the resin in the film production process, thermal decomposition and increase in gelled substance increase surface defects, foreign substances, and coarse protrusions on the surface in the film, or load on the extruder increases, and the production rate must be sacrificed, or control of the film thickness becomes difficult, and the film productivity decreases. In addition, too high intrinsic viscosity increases the polymerization time and the polymerization process, which becomes an important factor for increasing the cost.

The polymerization method of the polyester is not particularly limited, and examples thereof include an ester exchange method and a direct polymerization method. Examples of the transesterification catalyst include oxides of Mg, Mn, Zn, Ca, Li, Ti, etc., and compounds such as acetates. Further, examples of the polycondensation catalyst include compounds such as oxides and acetates of Sb, Ti, Ge, and the like.

The polyester after polymerization contains monomers, oligomers, by-produced acetaldehyde and the like, and therefore, it is preferable to carry out solid-phase polymerization at a temperature of 200 ℃ or higher under reduced pressure or by inert gas flow.

Additives such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, anchoring agents, and the like may be added as necessary in the polymerization of the polyester. Examples of the antioxidant include hindered phenol compounds and hindered amine compounds, examples of the heat stabilizer include phosphorus compounds, and examples of the ultraviolet absorber include benzophenone compounds and benzotriazole compounds.

The polyester may contain a roughened material, and the maximum particle diameter of the roughened material is preferably 0.2 μm or less. Examples of the roughening agent include inorganic particles such as silica, calcium carbonate, kaolinite, titanium dioxide, and silica alumina, and organic particles such as silicone, polymethyl methacrylate, and ethylvinylbenzene. The roughening agent may be used alone or in combination of 2 or more.

The release film of the present invention is industrially easily obtained by using a polyester film composed of the polyester as a base film, applying a liquid containing a polypropylene-based modified polyolefin resin and a crosslinking agent in a liquid medium on the polyester film, and drying, stretching and heat-treating the polyester film applied with the liquid to provide a resin layer.

In the present invention, the liquid medium constituting the liquid for forming the resin layer is preferably an aqueous medium. The aqueous medium includes water and an amphiphilic organic solvent, and means a solvent having a water content of 2% by mass or more, and may be water alone.

The amphiphilic organic solvent is an organic solvent having a solubility of water in an organic solvent of 5 mass% or more at 20 ℃ (the solubility of water in an organic solvent at 20 ℃ (described in, for example, a literature such as "solvent handbook" (published by society of society, 1990, 10 th edition)).

Specific examples of the amphiphilic organic solvent include alcohols such as methanol, ethanol, n-propanol and isopropanol, tetrahydrofuran and 1, 4-bis (tetrahydrofuran)Ethers such as an alkane, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, N-propyl acetate, isopropyl acetate, methyl propionate, ethyl propionate and dimethyl carbonate, ethylene glycol derivatives such as ethylene glycol N-butyl ether, organic amine compounds such as ammonia-containing diethylamine, triethylamine, diethanolamine, triethanolamine, N-dimethylethanolamine and N, N-diethylethanolamine, and lactams such as 2-pyrrolidone and N-methyl-2-pyrrolidone.

The liquid material for forming a resin layer can be prepared by adding a crosslinking agent to a liquid material of a polypropylene-based modified polyolefin resin.

As the liquid of the polypropylene-based modified polyolefin resin, an aqueous dispersion of the polypropylene-based modified polyolefin resin can be used. The method for dispersing the polypropylene-based modified polyolefin resin in an aqueous solution is not particularly limited, and examples thereof include the method described in international publication No. 02/055598.

The number average particle diameter of the dispersed particle diameter of the polypropylene-based modified polyolefin resin in the aqueous medium is preferably 1 μm or less, more preferably 0.8 μm or less, from the viewpoints of stability when mixed with other components and storage stability after mixing. Such a particle size can be achieved by the production method described in international publication No. 02/055598. The number average particle diameter of the polypropylene-based modified polyolefin resin was measured by a dynamic light scattering method.

The solid content concentration of the aqueous dispersion of the polypropylene-based modified polyolefin resin is not particularly limited, but is preferably 1 to 60% by mass, more preferably 5 to 30% by mass, in order to suitably maintain the viscosity of the aqueous dispersion.

The solid content concentration of the liquid for forming a resin layer obtained by mixing the aqueous dispersion of the polypropylene-based modified polyolefin resin and the crosslinking agent is not particularly limited, and may be appropriately selected depending on the lamination conditions, the target thickness, the performance, and the like. However, in order to form a uniform resin layer while maintaining the viscosity of the liquid material appropriately, the amount is preferably 2 to 30% by mass, and more preferably 3 to 20% by mass.

An antioxidant, an ultraviolet absorber, a lubricant, a colorant, and the like may be added to the liquid for forming the resin layer within a range not impairing the performance thereof.

In the present invention, as a method for coating the liquid for forming the resin layer on the polyester film, known methods such as gravure roll coating, reverse roll coating, wire bar coating, nozzle coating (リップコーティング), air knife coating, curtain coating, spray coating, dip coating, brush coating, and the like can be cited.

In the present invention, it is necessary to include a step of applying (in-line coating) a liquid material for forming a resin layer in a process for producing a polyester film, and drying, stretching, and heat-treating the liquid material together with the polyester film. Since the resin layer can be formed in a state where the degree of oriented crystallization of the surface of the polyester film is small by coating in the production process, the adhesion force between the polyester film and the resin layer is improved. Further, since the resin layer can be heat-treated at a higher temperature in a state where the polyester film is stretched as compared with off-line coating (post-coating), the releasability and the residual adhesive force can be improved without deteriorating the quality of the polyester film. Further, compared with off-line coating, the production process can be simplified, and the resin layer can be made thinner by stretching after coating, which is advantageous in terms of cost.

Next, an example of a method for producing a release film of the present invention will be described.

First, a sufficiently dried polyester is supplied to an extruder, sufficiently plasticized, melted at a temperature higher than a temperature at which fluidity is exhibited, passed through a filter selected as needed, and then extruded into a sheet shape by a T-die. The sheet was closely adhered to a cooling drum adjusted to a temperature of not higher than the glass transition temperature (Tg) of the polyester to obtain an unstretched film.

The obtained unstretched film is biaxially stretched to be biaxially oriented. The stretching method is not particularly limited, and a sequential biaxial stretching method or a simultaneous biaxial stretching method may be employed to produce the polyester film.

The release film of the present invention is produced by applying a liquid material for forming a resin layer in the above-mentioned polyester film production process, and drying, stretching and heat-treating the applied liquid material together with the polyester film.

In the simultaneous biaxial stretching method, the liquid material is applied to an unstretched film and dried, and then biaxially stretched in the longitudinal and width directions at stretching ratios of about 2 to 4 times, respectively, in the temperature range of from Tg to a temperature 50 ℃ higher than Tg of the polyester. The unstretched film may be subjected to preliminary longitudinal stretching by a factor of about 1.2 before being guided to the simultaneous biaxial stretching machine.

In the sequential biaxial stretching method, an unstretched film is heated with a roll, infrared rays, or the like and stretched in the longitudinal direction to obtain a longitudinally stretched film. The stretching is preferably conducted by a difference of 2 or more roll peripheral speeds, and the stretching is conducted in a temperature range of from Tg to a temperature 40 ℃ higher than Tg of the polyester by a factor of 2.5 to 4.0. The longitudinally stretched film is successively subjected to transverse stretching, heat fixing, and heat relaxation treatments in this order in the width direction to produce a biaxially oriented film. The transverse stretching is started at a temperature of from Tg to 40 ℃ higher than Tg of the polyester, and the highest temperature is preferably 100 to 40 ℃ lower than the melting point (Tm) of the polyester. The stretch ratio in the transverse direction is adjusted depending on the desired physical properties of the final film, and is preferably 3.5 times or more, more preferably 3.8 times or more, and still more preferably 4.0 times or more. After stretching in the longitudinal direction and the width direction, the film may be further stretched again in the longitudinal direction and/or the width direction, whereby the elastic modulus or the dimensional stability of the film can be improved.

In the case of producing a release film by the sequential biaxial stretching method, there are a method of applying a liquid material to an unstretched film and then stretching it in the longitudinal direction and stretching it in the transverse direction, and a method of applying a liquid material to a longitudinally stretched film and then stretching it in the transverse direction. The latter method is preferable for reasons of simplicity and ease of operation.

Immediately after the stretching, it is preferable to perform a heat-fixing treatment at a temperature lower than the Tm of the polyester by 50 to 10 ℃ for several seconds, and to perform a relaxation of 2 to 10% in the film width direction simultaneously with the heat-fixing treatment. After the heat-fixing treatment, the film is cooled to Tg or less to obtain a biaxially stretched film provided with a resin layer.

The polyester film as the substrate obtained by the above-mentioned production method is a single-layer film composed of 1 layer, but preferably the polyester film as the substrate has a multilayer structure in which 2 or more layers are laminated. By forming the polyester film into a multilayer structure, the surface roughness of each surface of the polyester film can be independently controlled.

When a multilayer film is used as the base polyester film, the layer provided with the resin layer in the outer layer of the multilayer film preferably does not contain the roughening substance. By not including the roughening material in the layer provided with the resin layer, the roughening material does not seep out to the interface between the base film and the resin layer and the surface of the resin layer, and it is possible to prevent the decrease in adhesion between the resin layer and the base film and the contamination of the adherend during peeling.

In the above-described production method, the film having a multilayer structure can be produced by a method in which the polyesters constituting each layer are melted, extruded using a multilayer die, laminated and fused before curing, and then biaxially stretched and heat-fixed; a method of melting and extruding 2 or more kinds of polyesters to form films, and laminating and fusing the polyesters in an unstretched state or after stretching. From the viewpoint of simplicity of the process, it is preferable to use a multilayer mold and perform lamination fusion before curing.

Since the release film of the present invention has good releasability from an adhesive material, a laminate can be formed by laminating an adhesive material on a resin layer.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The properties of the modified polyolefin resin, its aqueous dispersion and the release film were measured by the following methods.

(1) Constitution of modified polyolefin resin

With ortho-dichlorobenzene (d)₄) As solvent, at 120 deg.C¹H-NMR (GeMINI 2000/300, manufactured by Varian corporation, 300 MHz).

(2) Organic solvent content of aqueous dispersion

The aqueous dispersion or a product obtained by diluting the aqueous dispersion with water was directly charged into the apparatus by using a gas chromatography GC-8A manufactured by Shimadzu corporation, to determine the content of the organic solvent. The detection limit was 0.01 mass%.

The detailed conditions of the gas chromatography are as follows.

A detector: FID, carrier gas: nitrogen, column packing material: PEG-HT (5%) -Uniport HP (60/80 mesh) (manufactured by GL scientific instruments corporation), column size: diameter 3mm × 3m, sample input temperature (injection temperature): 180 ℃, column temperature: 80 ℃, internal standard substance: n-butanol.

(3) Solid content concentration of aqueous dispersion

The aqueous dispersion was weighed in an appropriate amount, and heated at 150 ℃ until the mass of the residue (solid content) became constant, to determine the solid content concentration.

(4) Number average particle diameter of polyolefin resin particles

The number average particle diameter was determined using a MICROTRACK particle size distribution analyzer UPA150(MODEL No.9340, dynamic light scattering method) manufactured by NIGHT CORPORATION. The refractive index of the resin used for the particle size calculation was 1.50.

(5) Peel strength of rubber-based adhesive

A pressure-sensitive adhesive tape (LP-24/rubber-based pressure-sensitive adhesive manufactured by Nichiban) having a width of 24mm and a length of 150mm was pressed against the resin layer side of the release film by a rubber roller to prepare a sample. The sample was held between a metal plate/a rubber plate/a sample/a rubber plate/a metal plate, left to stand under a load of 2kPa at 70 ℃ for 20 hours, and then cooled for 30 minutes or more to return to room temperature to obtain a sample for measuring peel strength. The peel strength between the adhesive tape and the release film of the sample for peel strength measurement was measured in a thermostatic chamber at 25 ℃ by a tensile tester (model 2020 precision Universal Material tester manufactured by Intesco corporation). The peel angle was 180 ℃ and the peel speed was 300 mm/min.

(6) Peel strength of acrylic adhesive

A polyester adhesive tape (No. 31B/acrylic adhesive manufactured by Nindon electric Co., Ltd.) having a width of 50mm and a length of 150mm was pressure-bonded to the resin layer side of the release film by a rubber roll to prepare a sample. The sample was held between a metal plate/a rubber plate/a sample/a rubber plate/a metal plate, left to stand under a load of 2kPa at 70 ℃ for 20 hours, and then cooled for 30 minutes or more to return to room temperature to obtain a sample for measuring peel strength. The peel strength between the adhesive tape and the release film of the sample for peel strength measurement was measured in a thermostatic chamber at 25 ℃ by a tensile tester (model 2020 precision Universal Material tester manufactured by Intesco corporation). The peel angle was 180 ℃ and the peel speed was 300 mm/min.

(7) Residual adhesion rate

A polyester tacky tape (No. 31B/acrylic adhesive manufactured by Rindong electrician Co., Ltd.) having a width of 50mm and a length of 150mm, which was peeled from the surface of a release film by the test for peel strength of the acrylic adhesive (6), was adhered to the corona-treated surface of a biaxially stretched polyester resin film (EMBLETPT-12 manufactured by Engico., Ltd., thickness of 12 μm), and left at room temperature under a load of 2kPa for 20 hours. Thereafter, the peel strength between the polyester adhesive tape and the biaxially stretched polyester resin film was measured in a constant temperature room at 25 ℃ by a tensile tester (model 2020 precision Universal Material tester manufactured by Intesco corporation). The peel angle was 180 ℃ and the peel speed was 300 mm/min. The peel strength obtained by this measurement was F1.

On the other hand, an unused polyester adhesive tape (No. 31B/acrylic adhesive manufactured by Nidok electric Co., Ltd.) having a width of 50mm and a length of 150mm was attached to a corona-treated surface of a biaxially stretched polyester resin film (EMBLETPT-12 manufactured by Youngco, Ltd., thickness 12 μm), and the film was left under a load of 2kPa at room temperature for 20 hours. Thereafter, the peel strength (peel angle 180 degrees, peel speed 300 mm/min) of the polyester adhesive tape and the biaxially stretched polyester resin film was measured in a tensile tester (model 2020 precision universal materials tester manufactured by Intesco corporation) in a thermostatic chamber at 25 ℃ and the obtained peel strength was F2.

The residual adhesion was obtained from the peel strengths F1 and F2 by the following formula.

Residual adhesion ratio (%) (F1/F2) × 100

(8) Contact angle

The film roll obtained by winding the obtained release film was allowed to stand at 40 ℃ for 3 days. After the treatment, the surface layer was cooled to remove the film, and the contact angle with water was measured by a liquid drop method for the surface of the release film on the resin layer side and the opposite surface thereof at a distance of 50m from the core. That is, pure water was dropped using a contact angle meter CA-D manufactured by Kyowa Kagaku K.K. under an environment of 20 ℃ and 65% RH so as to form a water droplet having a diameter of 2.0mm, and the contact angle after 10 seconds was measured. The average of 5 determinations was used.

The aqueous modified polyolefin resin dispersion for preparing a liquid for forming a resin layer was produced by the following method.

< production of Polypropylene-based modified polyolefin resin P-1 >

280g of a propylene-butene-ethylene terpolymer (VESTOPLAST 708 manufactured by Huels Japan, 64.8/23.9/11.3 (mass%)) was charged into a 4-neck flask, heated and melted under a nitrogen atmosphere, and then 32.0g of maleic anhydride as an unsaturated carboxylic acid and 6.0g of dicumyl peroxide as a radical generator were added thereto over 1 hour with stirring while maintaining the temperature in the system at 170 ℃. After the reaction was completed, the obtained reaction product was put into a large amount of acetone to precipitate a resin. This resin was further washed with acetone several times to remove unreacted maleic anhydride, and then dried under reduced pressure in a reduced-pressure dryer to obtain a polypropylene-based modified polyolefin resin P-1.

< production of Polypropylene-based modified polyolefin resin P-2 >

280g of a propylene-ethylene copolymer (propylene/ethylene: 81.8/18.2 (mass%), weight average molecular weight: 85, 000) was placed in a 4-neck flask, heated and melted under a nitrogen atmosphere, then 35.0g of maleic anhydride as an unsaturated carboxylic acid and 6.0g of di-t-butyl peroxide as a radical generator were added thereto over 2 hours with stirring while maintaining the temperature in the system at 180 ℃. After the reaction was completed, the obtained reaction product was put into a large amount of acetone to precipitate a resin. This resin was further washed with acetone several times to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum drier to obtain a polypropylene-based modified polyolefin resin P-2.

[ production of aqueous Polypropylene-based modified polyolefin resin Dispersion E-1 ]

60.0g of a polypropylene-based modified polyolefin resin (P-1), 45.0g of ethylene glycol N-butyl ether (Bu-EG, boiling point 171 ℃ C.), 6.9g of N, N-dimethylethanolamine (DMEA, boiling point 134 ℃ C., 1.0 equivalent per carboxyl group of the maleic anhydride component in the resin) and 188.1g of distilled water were charged into the above glass vessel using a stirrer equipped with a closable glass vessel having a pressure-resistant capacity of 1 liter with a heater, and the stirring was carried out at a rotational speed of 300rpm of a stirring blade. At this time, no precipitation of the resin occurred at the bottom of the vessel, and it was confirmed that the vessel was in a suspended state. Thus, this state was maintained, and after 10 minutes, the heater was powered on to heat the glass. The temperature in the system was then kept at 140 ℃ and further stirred for 60 minutes. Thereafter, the mixture was cooled to room temperature (about 25 ℃ C.) while stirring the mixture at a rotation speed of 300rpm by air cooling. Then, the resultant was subjected to pressure filtration (air pressure: 0.2MPa) using a 300-mesh stainless steel filter mesh (wire diameter: 0.035mm, plain weave) to obtain a milky yellow uniform polypropylene-based modified polyolefin resin aqueous dispersion E-1. Note that almost no resin remains on the filter.

[ production of aqueous Dispersion E-2 of Polypropylene-based modified polyolefin resin ]

P-2 was used as the polypropylene-based modified polyolefin resin. In a similar manner to the aqueous dispersion E-1 except for this, an aqueous polypropylene modified polyolefin resin dispersion E-2 was obtained.

[ production of aqueous Dispersion E-3 of Polypropylene-based modified polyolefin resin ]

250g of the aqueous polypropylene modified polyolefin resin dispersion E-1 and 90g of distilled water were charged into a 0.5L 2-neck round-bottomed flask, and the flask was heated by an oil bath under a magnetic stirrer and a Liebig cooler to distill off the aqueous medium. After about 90g of water and Bu-EG were distilled off, heating was terminated and the reaction mixture was cooled to room temperature. After cooling, the liquid contents in the flask were subjected to pressure filtration (air pressure 0.2MPa) through a 300-mesh stainless steel filter (wire diameter 0.035mm, plain weave) to obtain a milky-white uniform aqueous dispersion E-3 of a polypropylene-based modified polyolefin resin. The content of the organic solvent in the aqueous dispersion was 2% by mass.

[ production of polyethylene-modified polyolefin resin aqueous Dispersion E-4 ]

60.0g of maleic anhydride-modified polyolefin resin (BONDINE LX-4110 manufactured by Arkema Co., Ltd.), 90.0g of isopropyl alcohol (IPA), 3.0g of Triethylamine (TEA) and 147.0g of distilled water were charged into a glass vessel using a stirrer equipped with a closable pressure-resistant 1-liter capacity glass vessel equipped with a heater, and the rotational speed of the stirring blade was set to 300 rpm. Then, the temperature in the system is kept at 140-145 ℃ and stirred for 30 minutes. Then, the resulting mixture was cooled to room temperature (about 25 ℃ C.) while being stirred at a rotational speed of 300rpm in a water bath, and then subjected to pressure filtration (air pressure 0.2MPa) using a 300-mesh stainless steel filter (wire 0.035mm, plain weave) to obtain a milky uniform polyethylene-modified polyolefin resin aqueous dispersion E-4.

[ production of polyethylene-modified polyolefin resin aqueous Dispersion E-5 ]

60.0g of maleic anhydride-modified polyolefin resin (BONDINE HX-8210 available from Arkema corporation), 90.0g of IPA, 3.0g of TEA and 147.0g of distilled water were charged into a glass container using a stirrer equipped with a closable pressure-resistant 1 liter capacity glass container equipped with a heater. Then, the rotation speed of the stirring blade was set to 300rpm, the temperature in the system was maintained at 140 to 145 ℃, and the mixture was stirred for 30 minutes. Thereafter, the mixture was placed in a water bath and cooled to room temperature (about 25 ℃) while stirring at a rotation speed of 300 rpm.

The aqueous dispersion thus obtained, 180g of distilled water and 3.0g of DMEA were charged into a 0.5L 2-neck round-bottom flask, and the flask was heated with an oil bath under a magnetic stirrer and a Liebig-type cooler to distill off the aqueous medium. After about 180g of water and IPA were distilled off, heating was terminated and cooling was performed to room temperature. After cooling, the liquid contents in the flask were subjected to pressure filtration (air pressure 0.2MPa) using a 300-mesh stainless steel filter (wire diameter 0.035mm, plain weave) to obtain an aqueous polyethylene modified polyolefin resin dispersion E-5.

[ production of polyethylene-modified polyolefin resin aqueous Dispersion E-6 ]

60.0g of an acrylic polyolefin resin (PRIMACOR 5980I, manufactured by DOW chemical Co., Ltd.), 16.8g of TEA and 223.2g of distilled water were charged into a glass container using a stirrer equipped with a closable pressure-resistant 1 liter capacity glass container equipped with a heater. Then, the rotation speed of the stirring blade was set to 300rpm, the temperature in the system was maintained at 140 to 145 ℃, and the mixture was stirred for 30 minutes. Thereafter, the mixture was placed in a water bath and cooled to room temperature (about 25 ℃) while stirring at a rotation speed of 300 rpm. Then, the resulting mixture was subjected to pressure filtration (air pressure: 0.2MPa) using a 300-mesh stainless steel filter (wire diameter: 0.035mm, plain weave) to obtain a slightly cloudy aqueous dispersion E-6. At this time, almost no resin remained on the filter.

The composition and physical properties of the modified polyolefin resin and the physical properties of the resulting aqueous dispersion are shown in table 1.

TABLE 1

Example 1

< preparation of liquid for Forming resin layer >

An aqueous dispersion E-1 of a polypropylene-based modified polyolefin resin and an aqueous polyvinyl alcohol solution (Japan Vam)&VC-10 manufactured by Poval, polymerization degree: 1000, solid content concentration: 8% by mass) and as a crosslinking agentAqueous solutions of oxazoline compounds (EPOCROS WS-700, manufactured by Nippon catalytic Co., Ltd., solid content concentration 25 mass%) were mixed so that the solid content ratio of each component became the value shown in Table 3 to obtain liquid products.

< production of mold Release film >

Polyethylene terephthalate (polymerization catalyst: antimony trioxide, intrinsic viscosity: 0.62, glass transition temperature: 78 ℃, melting point: 255 ℃) B to which silica particles shown in Table 2 were added was fed into an extruder I (screw diameter: 50mm), polyethylene terephthalate A was fed into an extruder II (screw diameter: 65mm), melted at 280 ℃, and then the melts were laminated in confluence before reaching the outlet of the T-die. The cast film was extruded from the outlet of a T die so that the layer thickness ratio (I/II) was 4/6 and the total thickness was 380 μm, and rapidly cooled and solidified to obtain an unstretched film. The unstretched film sheet was stretched to 3.5 times at 85 ℃ by a roll longitudinal stretcher.

Then, the process of the present invention is carried out,the liquid for forming a resin layer prepared by the above method was applied to a 120-mesh gravure roll to give a thickness of 5g/m²After coating the surface of the polyester film layer extruded from the extruder I, it was passed through a hot air drying oven at 50 ℃ for 20 seconds.

Thereafter, the film sheet was continuously fixed at its end portion to a jig of a flatbed stretcher, stretched 4.5 times in the transverse direction at 100 ℃, and then heat-treated at 230 ℃ for 3 seconds with a relaxation rate of 3% in the transverse direction to obtain a release film having a thickness of 25 μm in which a resin layer was provided on one surface of 2 kinds of 2-layer polyester films.

The obtained release film was wound into a roll having a length of 500m under conditions of a width of 800mm, a winding tension of 118N/m, a winding contact pressure of 118N/m, and a winding speed of 100 m/min on a paper tube having an outer diameter of 10.5cm by using a hard chrome-plated pressure roller (maximum height SRmax of 7 μm) on the surface. The coefficient of friction of the pressure roller was 0.3 り, and the wrap angle (hugging き angle) of the film was 120 °.

TABLE 2

Examples 2 to 15 and comparative examples 4 to 9

The same procedure as in example 1 was carried out except that the thickness ratio (I/II/I) of the layers was changed to 2/6/2 when the polyester film was changed to 2 types and 3 layers, the thickness ratio (I/II) of the layers was changed to 10/0 when the polyester film was changed to a single layer, and the types of resins and the compositions of the liquid materials for forming the resin layers of the respective layers forming the film were changed to those described in table 3, thereby obtaining a release film.

Comparative example 1

The liquid material for forming a resin layer prepared in example 1 was coated on a corona-treated surface of a biaxially stretched polyester film (EMBETPEEPT-38 manufactured by YOUGHIGO CO., LTD., thickness 38 μm) using a Meyer bar coater, and then dried at 120 ℃ for 30 seconds to form a resin layer having a thickness of 0.5 μm on the film, and then cured at 50 ℃ for 2 days to obtain a release film.

Comparative examples 2 to 3

A release film was obtained in the same manner as in comparative example 1, except that the composition of the liquid material for forming a resin layer was changed to the composition shown in table 3.

The compositions of the liquid materials for forming resin layers used in examples 1 to 15 and comparative examples 1 to 9 and the properties of the release films are shown in table 3.

TABLE 3

The release films obtained in examples 1 to 15 had a peel strength between the resin layer and the rubber-based adhesive of more than 3.0N/cm, sufficient adhesion, and the residual adhesion rate of the acrylic adhesive after the adhesion to the resin layer was 80% or more, and the resin layer component was not easily transferred to the adhesive material, and even when the release film was wound into a roll, the contact angle of water on the surface opposite to the surface provided with the resin layer was 80 ° or less, and the release film was not contaminated with the resin layer.

On the other hand, in the release films obtained in comparative examples 1 to 3, since the resin layer was provided by off-line coating (post-coating), the components of the resin layer were easily transferred to the adhesive material, the residual adhesion rate of the acrylic adhesive after being attached to the resin layer was low, and if the release film was wound in a roll shape, the opposite surface to the surface provided with the resin layer was contaminated with the resin layer.

The release films obtained in comparative examples 4 to 6 had low peel strength between the resin layer and the rubber-based adhesive because the olefin component constituting the resin layer was polyethylene-based.

In addition, since the resin layers of the release films obtained in comparative examples 7 to 8 were not the configuration specified in the present invention, the components of the resin layers were easily transferred to the adhesive material, and the residual adhesion rate of the acrylic adhesive after being attached to the resin layers was low.

The release film obtained in comparative example 9 had a large content of the crosslinking agent in the resin layer, and therefore it was difficult to peel off the tacky adhesive material attached.

Claims

1. A mold release film characterized in that a resin layer is provided on one surface of a polyester film,

the residual bonding rate of the adhesive is more than 80% after the acrylic adhesive is adhered on the resin layer, and,

the contact angle of water on the surface opposite to the surface provided with the resin layer is 75 DEG or less.

2. The release film according to claim 1, wherein the resin layer further contains polyvinyl alcohol, and the content of the polyvinyl alcohol is 10 to 1000 parts by mass with respect to 100 parts by mass of the polypropylene-based modified polyolefin resin.

3. The release film according to claim 1 or 2, wherein the polyester film has a multilayer structure in which 2 or more kinds of layers are laminated.

4. A process for producing the release film according to claim 1, which comprises a step of coating a polyester film with a liquid material comprising 100 parts by mass of a polypropylene-based modified polyolefin resin having a modifying component ratio of 1 to 10% by mass, 1 to 50 parts by mass of a crosslinking agent, and a liquid medium, and a step of drying, stretching, and heat-treating the polyester film coated with the liquid material.