JP2010274513A - Thermal transfer sheet and printed matter thereof - Google Patents

Abstract

[PROBLEMS] To provide excellent fading resistance and surface resistance, prevent photodegradation reaction from the end of the layer, have high safety to the body even when a child or pet licks directly, and has sufficient UV-absorbing ability, Also provided are a thermal transfer sheet and a printed product thereof in which the binder resin is not discolored.
In a thermal transferable sheet, at least a part of one surface of a base sheet is provided with two or more transferable protective layers, and an ultraviolet absorber is contained in the outermost layer of the transferable protective layer. . Furthermore, the ratio P (P = WB / wu) between the weight average molecular weight WB of the binder resin contained in the transferable protective layer and the weight average molecular weight wu of the ultraviolet absorber contained in the transferable protective layer is 12 ≦ P It is in the range of ≦ 1300.
[Selection] Figure 1

Description

  The present invention relates to a thermal transfer sheet provided with a protective layer for protecting an image formed by various image recording apparatuses, particularly an image using a dye. Furthermore, the present invention relates to an image formed product (printed product) protected by using the thermal transfer sheet which is heated and transferred by various methods.

  The above-described thermal transferable sheet is also called a thermal ribbon. For example, there is a configuration in which a thermal transferable ink layer is provided on one side of a base sheet and a heat-resistant slipping layer (backcoat) is provided on the other side. . Using such a heat-transferable sheet, predetermined heating is performed from the thermal head of the thermal printer, and a part of the heat-transferable ink layer is melted and transferred to the transfer medium side, or sublimation in the heat-transferable ink layer By sublimating the dye and transferring it to the transfer medium side, a predetermined thermal transfer image formation, that is, printing, is performed.

  At present, the thermal transfer recording method has been widely used for recording image information on cards such as identification cards, amusement output materials, etc., because the advanced functions of thermal printers have advanced and various images can be recorded easily. Under such circumstances, there is a growing demand for durability of the transfer image recording medium obtained by the thermal transfer recording method, and in recent years, a protective layer has been formed so as to cover the transferred image recorded using the thermal transfer sheet. Many improvements have been made to improve the durability of the transferred image recording medium.

  However, when a transfer image recording medium obtained by a thermal transfer recording method using a thermal transfer sheet is exposed to sunlight or illumination light for a long time, the transfer image portion is affected by ultraviolet rays or ozone in the atmosphere. There was a problem that the color faded and the recording became unclear. Therefore, a method for providing a protective layer on a transferred image by a thermal transfer recording method using a thermal transfer sheet having a thermal transferable protective layer blended with an ultraviolet absorber in order to impart fade resistance to a recorded transferred image. Has been adopted.

  In the following Patent Document 1 and Patent Document 2, a layer using an ultraviolet absorber is provided to avoid fading or browning due to ultraviolet rays. However, in this configuration, an ultraviolet absorber is mixed in the outermost layer, but improvement of surface resistance (hardness, scratch resistance, etc.) is not considered, and fading or browning due to ozone in the atmosphere, No measures for abnormal transcription are taken into consideration. Further, there is a concern that the photodegradation reaction from the end of the layer starts and promotes fading.

  Further, in Patent Document 3, a layer containing an ultraviolet absorber exists in the outermost layer of the printed material after thermal transfer, and as described above, deterioration from the end portion corresponding to the layer thickness to the image portion occurs. When a sheet or pet licks the sheet surface directly, there is a problem such as a physical influence by the ultraviolet absorber component.

  In Patent Document 4, a thermal transfer resin and an ultraviolet absorber are reactively bonded to the protective layer.

  Patent Document 5 mainly relates to an ID card, but there is no ultraviolet absorber in the outermost layer in the printed product after transfer and the layer relating to transfer adhesion, and an ultraviolet absorbing layer in which the ultraviolet absorber is bonded to a binder resin. It is said. In this case, the effect of hardness on the outermost layer of the printed material is considered to be less likely to occur, but the layer thickness and the amount of bonding are required to maintain the UV absorbing ability, and the thickness of the layer is too thick. When winding the number of sheets (roll), there is a possibility that it cannot be mounted on the printing apparatus. Or, when the thickness is made appropriate, the amount of bonding is insufficient, and there is a possibility that the ultraviolet absorbing ability is lowered.

  In Patent Document 6, an ultraviolet absorber is mixed in the outermost layer on the substrate, but the binder resin is limited to a polyester resin and an epoxy resin. With these resins, the color on the image can be protected, but the binder itself may be discolored.

Japanese Patent Laid-Open No. 10-315641 Japanese Patent No. 2000-71626 JP-A-8-324142 Japanese Patent No. 4113899 Japanese Patent No. 3345684 Japanese Patent No. 2762751

  The object of the present invention is, in view of the above-mentioned present situation, excellent in fading resistance and surface resistance, prevents photodegradation reaction from the layer edge, and is highly safe to the body even when a child or pet licks directly. Another object of the present invention is to provide a thermal transfer sheet and a printed product thereof that have sufficient ultraviolet absorbing ability and do not discolor the binder resin.

In the present invention, in order to solve the above problems,
The thermal transferable sheet according to claim 1 comprises two or more transferable protective layers on at least a part of one surface of the base sheet, and an ultraviolet absorber is contained in the outermost layer of the transferable protective layer. It is characterized by that.

  The heat transferable sheet according to claim 2, wherein in the transferable protective layer containing the ultraviolet absorber, the weight average molecular weight WB of the binder resin contained in the transferable protective layer and the ultraviolet absorber contained in the transferable protective layer. The ratio P (P = WB / wu) to the weight average molecular weight wu is in the range of 12 ≦ P ≦ 1300.

  The printed matter according to claim 3 includes an image formed on a transfer medium and two or more transfer protection layers formed so as to cover at least a part of the image. The thermal transfer sheet according to claim 1 or 2 is used.

  According to the present invention, the thermal transfer sheet has two or more transferable protective layers, and the outermost layer contains an ultraviolet absorber, thereby preventing the color fading of a printed material using the same and the gloss of the image. Thus, a thermal transfer sheet and a printed material thereof having improved safety so that the body is not affected even when a child or pet directly licks can be obtained.

It is sectional drawing which shows an example of a structure of the thermal transfer sheet of this invention.

Hereinafter, the thermal transferable sheet of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic cross-sectional configuration when three layers are laminated on a base material as an example of the thermal transfer sheet according to the present invention. This thermal transfer sheet has a thermal transfer ink layer (yellow) 3, a thermal transfer ink layer (magenta) 4, a thermal transfer ink layer (cyan) 5, and a transfer-related layer 7 on one surface of the base sheet 1. The transfer-related layer 7 is sequentially provided in the longitudinal direction of the base sheet 1, and the transfer-related layer 7 has a two-layer structure including a release layer 6 and a transferable protective layer 8. It is provided on one side. And it is designed to peel at the interface between the release layer 6 and the transferable protective layer 8 while leaving the release layer 6 on the base sheet 1 side during thermal transfer. The transfer protective layer 8 is composed of two layers, a release layer 9 and an adhesive layer 10. Further, a heat resistant slipping layer 2 is provided on the other surface of the substrate sheet 1.

  The transfer-related layer 7 is shown in a three-layer structure in the example of FIG. 1, but further has a multilayer structure in which intermediate layers having functions such as an intermediate layer 1, an intermediate layer 2,. It is also possible and not limited to the configuration of FIG. Examples of functions that can be imparted to the intermediate layer include, but are not limited to, a heat resistance improving layer, a printing wrinkle reducing layer, or a layer that absorbs and smoothes unevenness of photographic paper. You can also have it.

  The base sheet 1 can be made of a material excellent in heat resistance and strength that is not softened and deformed by heat pressure during thermal transfer recording. Specifically, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, acetate, polycarbonate, polysulfone, polyimide, polyvinyl alcohol, aromatic polyamide, aramid, polystyrene, etc., synthetic resin film, condenser paper, paraffin paper, etc. Paper or the like can be used alone or in combination. Among these materials, a film made of polyethylene terephthalate is preferable in view of physical properties, workability, cost, and the like. The thickness may be about 2 to 50 μm in consideration of operability and workability, but is more preferably about 2 to 15 μm in consideration of handling properties such as transfer suitability and workability. Moreover, you may give an easily bonding process etc. to the surface and / or back surface of the base material sheet 1 as needed.

  The heat-resistant slip layer 2 is particularly necessary when a thermal head is used as a heating means at the time of thermal transfer recording, because the thermal head is not fused, and is positioned on the back surface when the thermal transfer sheet is wound with a roll. It is provided so that it does not stick to the transfer-related layer or ink layer, or because the dye or pigment of the thermal transfer ink layer does not migrate. Furthermore, it has releasability.

  The constituent material of the heat-resistant slip layer 2 is not limited to the following, but in particular, it was prepared by blending a functional additive imparting releasability and slipperiness, a binder, a curing agent, a solvent and the like. It is desirable to use a coating liquid. The thickness is preferably about 0.1 to 5 μm in terms of dry film thickness.

Specifically, the material of the heat-resistant slip layer 2 is an ultraviolet curing coating film of an acrylic oligomer, a synthetic resin such as polyester, polyurethane, polyacetal, polyamide, polyimide, or a synthetic resin thereof. As a curing agent, an isocyanate compound, Examples thereof include a cured coating film made of a composition to which an epoxy curing agent, a phenol curing agent, a melamine curing agent, or the like is added. Furthermore, the cured coating film which consists of what added release agents, such as a fluorine type, a silicone type, an alkyl type, an acrylic type, or the thing which copolymerized silicone can also be mentioned.
Further, a filler may be added to the heat resistant slipping layer as necessary. Examples of the filler to be added include silicone or fluorine powder, silica and resin powder, talc, calcium carbonate, resin filler, natural minerals such as montmorillonite, and flake-like filler.

  Conventionally known thin film forming methods such as a dipping method, a roll coating method, a screen printing method, a spraying method, a gravure printing method and the like used in the usual thin film formation are applied as the coating method of the coating liquid constituting the heat resistant slipping layer 2 Can be used. The optimum thickness varies depending on the type of coating liquid, the processing machine and the processing conditions, and is not particularly limited. Specifically, the thickness after drying is about 0.1 to 5 μm, preferably 0. It may be 5 to 3 μm. When the thickness is less than 0.1 μm, it is difficult to form a uniform coating film, and sufficient heat resistance may not be obtained.

  The thermal transfer ink layers 3, 4, and 5 are layers formed by supporting a thermally transferable dye or pigment with an arbitrary binder resin. As the dye or pigment, any dye or pigment used in a sublimation type or heat-sensitive melting type thermal transfer ink layer of a conventionally known thermal transfer sheet can be used, and is not particularly limited. .

  As the sublimation dye contained in the constituent material of the sublimation type thermal transfer ink layer, a sublimation disperse dye is preferably used. Specifically, examples of the yellow component include Solvent Yellow 56, 16, 30, 93, 33, Disper Yellow 201, 231, 33, and the like. As the magenta component, C.I. I. Disperse thread 60, disperse violet 26, C.I. I. Solvent Red 27, or C.I. I. Solvent Red 19 may be mentioned. Further, as the cyan component, C.I. I. Disperse blue 354, 24, C.I. I. Solvent Blue 63, 36 etc. are mentioned.

  The binder resin carrying the sublimable dye is not particularly limited, but cellulose resins such as ethylene cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate, polyvinyl alcohol, and polyacetic acid. Examples thereof include vinyl resins such as vinyl, polyvinyl butyral, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins. Among these, polyvinyl butyral, styrene-acrylonitrile copolymer resin, and phenoxy resin are preferably used.

  The ratio of the dye to the binder contained in the constituent material of the sublimation type thermal transfer ink layer is preferably about dye / binder = 10/100 (parts by weight) to 300/100. When the ratio of the dye / binder is less than 10/100, the amount of the dye is too small, the color development sensitivity becomes insufficient, and it becomes difficult to obtain a good thermal transfer image. On the other hand, when the ratio exceeds 300/100, the solubility of the dye in the binder is extremely lowered, so that the storage stability of the heat transferable ink layer is deteriorated and the dye is likely to precipitate.

  The dye contained in the constituent material of the heat-sensitive melt-type heat transferable ink layer is not limited to the following, but is a diarylmethane, triarylmethane, thiazole, methine, azomethane, xanthene Examples of heat-sensitive transfer dyes commonly used, such as azazine, axazine, thiazine, azine, acridine, azo, spirodipyran, isodolinospiropyran, fluorolane, rhodamine dactam, anthraquinone Can do.

  Further, the pigment to be included in the constituent material of the heat-sensitive melt type thermal transfer ink layer is not limited to the following, but is a known organic pigment or inorganic pigment, specifically, carbon black, azo, Mention may be made of pigments such as phthalocyanine, cynaridon, thioindigo, anthraquinone and isoindoline.

Examples of the binder resin carrying these pigments include styrene resins such as polystyrene and poly α-methylstyrene, acrylic resins such as polymethyl methacrylate and polyethyl acrylate, polyvinyl chloride, polyvinyl acetate, and vinyl chloride. Vinyl acetate copolymers, vinyl butyral such as polyvinyl butyral, polyvinyl acetal, polyester resin, polyamide resin, epoxy resin, polyurethane resin, petroleum resin, ionomer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, etc. Synthetic resins, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified maleic resin, polyisobutylene rubber, butyl rubber, styrene-butadiene rubber, butadiene-acrylonitrile Rirugomu, derivatives of natural resins and synthetic rubber polychlorinated olefins such as carnauba wax, can be mentioned waxes such as paraffin wax. Of these, polyesters and epoxy resins are preferably used.

  The ratio of the dye and / or pigment (hereinafter referred to as color material component) and the binder contained in the heat-sensitive melt-type heat transferable ink layer is from color material component / binder = 1/100 (parts by weight) to 200 / About 100 is preferable. This is because if the ratio of the color material component / binder is less than 1/100, the color material is too small and it becomes difficult to obtain a good thermal transfer image. This is because the cohesive force of the heat transferable ink layer is extremely reduced, so that the storage stability of the heat transferable ink layer is deteriorated.

The transfer related layer 7 is provided on the same surface of the base sheet 1 as the thermal transfer ink layers 3, 4, and 5. This transfer-related layer 7 has a multilayer structure of at least a release layer 6 and a transferable protective layer 8 and is provided on the substrate sheet 1 via the release layer 6. The layer 6 is peeled off at the interface between the release layer 6 and the transferable protective layer 8 while leaving the layer 6 on the substrate sheet 1 side, and the transferable protective layer 8 is transferred to the transfer medium side.
The release layer 6 may be a single type of resin or may contain two or more types of resins as long as it has good adhesion to the base sheet 1 and normally adheres to the transferable protective layer 8. However, it peels off from the transferable protective layer 8 without transfer failure during thermal transfer.

  Further, the release layer 6 may not be necessary. For example, the contact state between the release layer 9 and the surface of the base sheet 1 is normally close and does not cause stagnation due to poor contact, and the release layer 9 is clean from the base sheet 1 only during transfer heating. This is the case where the entire surface can be peeled off and the necessary gloss can be obtained.

  Examples of the constituent material of the release layer 6 include, but are not limited to, water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, natural rubber such as chlorinated rubber and cyclized rubber. Rubber derivatives, waxes such as natural wax, synthetic wax, fiber derivatives such as nitrocellulose, cellulose acetate, cellulose, cellulose acetate propionate, acrylic, polyurethane, polyamide, polyimide, polyacetal, chlorinated Examples include polyolefin resins, vinyl chloride-vinyl acetate copolymer systems, olefin-based thermoplastic resins, melamine-based, epoxy-based, polyurethane-based, silicone-based thermosetting resins, and the like.

From these materials, at least two kinds of resins are selected, and one of them is a resin similar to the main binder of the base sheet 1 and the constituent material of the release layer 6 is adjusted. The adhesion to the material sheet can also be controlled.
More specifically, when the base sheet is a polyester resin film, a mixture prepared by mixing a polyester resin and another resin in a common solvent may be used. In the case of a resin-based film, a film prepared by mixing a polystyrene resin and another resin in a common solvent may be used to form a thin film.

In the constituent material of the release layer 6, the addition amount of the resin similar to the main binder of the base sheet 1 is 0.2 to 40 parts by weight, preferably 0.5 to 100 parts by weight when the main binder is 100 parts by weight. The amount is about 25 parts by weight, and may be appropriately selected in consideration of the compatibility of the resin, the dissolving solvent, the drying conditions, and the compatibility with the resin used for the release layer.
In this case, it is preferable that the two are compatible as much as possible, but this does not necessarily mean that they should be compatible, and they are mixed evenly with a common good solvent and evenly dispersed even if they are not completely compatible. It doesn't matter if it is transparent.
However, in that case, care should be taken to ensure that there are no defects such as separation or repellency on the dry coating surface resulting in sea islands, segregation on the surface or back surface of the coating film, or segregation over time. There is a need.

  The transferable protective layer 8 constituting a part of the transfer related layer 7 is a layer for protecting the transfer image by transferring the transfer image recorded on the transfer medium so as to cover the transfer image. Since it is required to have a role to protect from scratches, ultraviolet rays, ozone, etc. and gloss as a design property, it is also transferred to the transfer medium by the thermal transfer method, so it always has adhesiveness to the transfer medium. In addition, it is also necessary to have releasability to easily peel from the base sheet side during thermal transfer.

  In order to satisfy such requirements, in the thermal transferable sheet of the present invention, the transferable protective layer 8 has a multilayer structure including at least a release layer 9 and an adhesive layer 10. The transferable protective layer 8 is laminated on the release layer 6 so that the release layer 9 and the release layer 6 are in contact with each other. As described above, two or more layers may be provided, and an intermediate layer having functionality may be additionally provided.

  The release layer 9 is positioned on the outermost layer when transferred onto the transfer medium, but it has transparency, friction resistance, contamination resistance, scratch resistance, mold release, hardness, heat resistance, Various properties such as ozone resistance and design properties such as gloss may be required.

Examples of the binder constituting the release layer 9 include, but are not limited to, styrene resins such as polystyrene and poly α-methylstyrene, acrylic resins including polymethyl methacrylate, polyethyl acrylate, and the like, and styrene. Copolymer, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal and other vinyl resins, polyester resins, polyamide resins, epoxy resins, polyurethane resins, petroleum resins, ionomers, Synthetic resins such as ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified maleic acid resin, ester gum, polyisobutylene , Butyl rubber, styrene - butadiene rubber, butadiene - acrylonitrile rubber, derivatives of natural resins and synthetic rubber such as polychlorinated olefins, carnauba wax, waxes such as paraffin wax is used.
In addition, engineering plastics such as polycarbonate, super engineering plastics, and the like can also be used from the viewpoint of dissolving solvent, viscosity, hardness, and the like. Among these, acrylic resins and cellulose derivatives can be mentioned.

  In some cases, a resin having an aromatic ring is preferably used. It has the steric hindrance due to the ring structure of the aromatic ring and entanglement of the aromatic ring, the hardness of the surface due to the denseness of the resin, the aromatic surface structure, etc. Can be granted. However, there is a concern about yellowing due to aromatic rings, so care should be taken in use.

  Examples of the resin having an aromatic ring include, but are not limited to, for example, styrene resin, xylene resin, phenol resin, ABS resin, phenoxy resin, ACS resin, AES resin, aniline resin, isocyanate resin, aromatic ring polyimide resin Oxetane resin, phthalic acid resin, ester resin, terephthalic acid resin, novolak resin, benzoxazine resin, resol resin, acenaphthylene, naphthalene, and other aromatic resins, AS resin, ABC resin, ASA resin, SAS resin, ACS resin, AMA resin, MS resin, MBS resin, nylon resin, polyester resin, polyarylate resin, PEEK resin, PEKK resin, PSU resin, PES resin, benzophenone, PBI resin, quinazoline resin, carbonate resin, etc., and aromatic ring Engineer with Mention may be made of a ring of plastic, super engineering plastics. Of course, the resin may be a copolymer resin with the resin having the aromatic ring, or the resin itself or a mixture.

  By mixing or copolymerizing the resin constituting the adhesive layer 10 and the resin having an aromatic ring, the compatibility problem can be avoided. Furthermore, the mixing amount can be freely changed. By increasing the molecular weight, it is possible to closely control the specific gravity of the resin in the layer and the free movement volume when the coating is formed. If necessary, the release layer 9 and the adhesive layer 10 can be formed into a cured coating film using a curing agent. However, in particular, the adhesive layer 10 can have both heat resistance and transferability.

  By not adding an ultraviolet absorber to the release layer 9 and imparting the ultraviolet absorbing ability to the adhesive layer 10, it is possible to share the role of each layer with respect to color resistance. The reason is as follows. First, when the thermal transferable protective layer 8 is transferred onto the transfer medium, the adhesive layer 10 exists immediately above the transferred image. Therefore, the end of the layer caused by ultraviolet rays is caused by the action of the ultraviolet absorber contained in the adhesive layer 10. The print color can be effectively protected by avoiding fading and color separation. Furthermore, since the peeling layer 9 is located on the outermost surface on the transfer medium and does not contain an ultraviolet absorber, it is possible to further improve the physical safety when a child or a pet licks the printed matter.

  Since the release layer 9 is located on the outermost surface on the medium to be transferred, not only ozone resistance but also transparency, friction resistance, contamination resistance, scratch resistance, releasability (transferability), hardness, design (Gloss), adhesion, etc. are required. For that purpose, silica, calcium carbonate, kaolin, talc, silicone powder, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, satin white, zinc carbonate, carbonic acid, as long as ozone, gloss, adhesion, and transferability are not impaired. Magnesium, aluminum silicate, calcium silicate, magnesium silicate, silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalosite, magnesium hydroxide and other inorganic fillers, acrylic plastic pigment, styrene Organic fillers such as plastic pigments, microcapsules, urea resins, and melamine resins, waxes such as PE, carnauba, and paraffin, and release agents such as silicone and fluorine may be added as appropriate. These may be liquid or solid, and the shape is not particularly limited, and an appropriate one is selected from various shapes such as flakes and true spheres. That's fine.

  However, although easy peel transferability at the time of thermal transfer is particularly sought, if too many releasable additives are added to the release layer, due to bleeding over time, etc. Since peeling may occur between the adhesive layer and the release layer, it is necessary to select an appropriate addition amount. The thickness of the release layer 9 may be about 0.2 to 5 μm (dry thickness), more preferably about 0.3 to 2.0 μm (dry thickness).

The basic physical properties required for the adhesive layer 10 are that it is transferred to the transfer medium side by thermal transfer to form a protective layer, the film is cut off during transfer, the thermal adhesiveness to the transfer medium is good, and transparent These are good properties, do not impair the sharpness of the transferred image of the transferred image recording medium, further maintain the ultraviolet absorbing ability, and have ozone resistance.
In the present invention, the printed matter is designed so that the ability of the ultraviolet absorber can be maximized, and other glossiness, transferability, safety, and the like are considered.

The constituent material of the adhesive layer 10 is not limited to the following, for example, acrylic resins, polystyrene, styrene resins such as poly α-methylstyrene, acrylic resins such as polymethyl methacrylate, polyethyl acrylate, Polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal and other vinyl resins, phenoxy resin, phenol resin, polyester resin, polyamide resin, epoxy resin, polyurethane resin, petroleum resin, ionomer , Synthetic resins such as ethylene-acrylic acid copolymer and ethylene-acrylic acid ester copolymer, cellulose derivatives such as nitrocellulose, ethyl cellulose and cellulose acetate propionate, rosin, rosin-modified maleic acid resin, ester gum, polyester Isobutylene rubber, butyl rubber, styrene - acrylonitrile rubbers, natural resins and derivatives of synthetic rubber polychlorinated olefins such as carnauba wax, waxes such as paraffin wax - butadiene rubber, butadiene.
Among these, acrylic resins, polyesters, epoxies, phenoxy resins, and the like can be given. Of course, as long as heat transfer adhesiveness can be provided, the resin is not limited to a thermoplastic resin, and a thermosetting resin or a mixture of a curing agent with the thermoplastic resin may be used. However, acrylic resins are preferred because of their high transparency and high light resistance.

In the present invention, the ratio P (P = WB / wu) between the weight average molecular weight (WB) of the binder of the layer and the weight average molecular weight (wu) of the ultraviolet absorber is defined. When the ratio P is larger than 1300, either the molecular weight WB of the binder is too large, or the molecular weight wu of the ultraviolet absorber is too small.
That is, when the binder molecular weight is too large, there is a problem that it is difficult to apply due to high viscosity, or the solvent solubility is poor, or the viscosity at the time of thermal transfer increases, making it difficult to transfer at the target interface. Moreover, the diffusion of the UV absorber during thermal transfer is inhibited, and the amount of the UV absorber dissolved in the binder is also affected.
On the other hand, when the molecular weight of the ultraviolet absorber is small, the diffusion becomes too large and there is a risk of diffusion to adjacent layers.
On the contrary, when the ratio P is smaller than 12, it is considered that the molecular weight of the binder is small and the viscosity is low, so that the coating is in a good direction and the adhesion with the multilayer is improved, but the film is It may become brittle and inferior in transferability. Alternatively, the molecular weight of the UV absorber may be large, but in this case, the UV absorber is difficult to dissolve in the binder, and conversely difficult to diffuse, preventing uniform distribution in the layer and absorbing UV light. There is a possibility that the effect of the agent is difficult to be effectively exhibited.
Therefore, in the present invention, the ratio P between the molecular weight of the ultraviolet absorber and the molecular weight of the binder is defined to be 12 ≦ P ≦ 1300. Under these conditions, the ultraviolet absorber can act efficiently.
Further, in the present invention, the protective effect is promoted by the presence of the adhesive layer 10 containing an ultraviolet absorber immediately above the print image surface, and further, since the ultraviolet absorber is not contained in the outermost layer of the printed matter, It is possible to efficiently combine effects such as increased safety.
In the present invention, a non-reactive UV absorber is used. At the time of thermal transfer, the outermost layer on the base sheet is mainly softened and transferred and adhered. At that time, the ultraviolet absorber can be diffused and exist throughout the outermost layer until reaching the surface or edge of the formed image.

As functional additives to be mixed in the constituent material of the adhesive layer 10, in addition to UV absorbers and light stabilizers typified by hindered amines, thermal antioxidants typified by hindered phenols, fluorescent brighteners , Antistatic agents, flame retardants, and the like. These additives can be mixed with the release layer 10 described above to such an extent that the required physical properties are not affected.
In the present invention, in particular, by mixing an ultraviolet absorber or a light stabilizer into the adhesive layer 10, the ultraviolet absorbing ability is evenly distributed even during thermal transfer, and the fading of the image can be prevented efficiently.
In addition, since UV absorbers and light stabilizers are not mixed in the outermost layer of the printed matter, the possibility of bleeding on the surface in various environments is reduced, and even if it comes out, the concentration is low and the safety is more The effect is high, and it is possible to prevent a decrease in gloss over time.

  The adhesive layer 10 may be provided in the form of a thin film by preparing a coating liquid by blending the functional additive, binder, solvent and the like as described above. The thickness of the release layer is preferably about 0.2 to 5 μm (dry thickness), but is not limited thereto.

  Specific examples of the ultraviolet absorber added and mixed in the adhesive layer 10 include those of benzotriazole, benzophenone, triazine, and salicylate, and those including JP-A-59-196292 and JP-A-59. -158287, JP-A 63-74686, JP-A 59-196292, JP-A 62-229495, JP-A 63-122596, JP-A 61-283595, Examples thereof include compounds described in JP-A-1-204788 and the like, and known compounds that improve image durability in photographs and other image recording materials.

  Examples of the benzotriazole-based ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1- Methyl-1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol, 2- (2H-benzotriazol-yl) -4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol and the like, mixtures thereof, modified products, Polymers and derivatives can be exemplified, and these can be used alone or in combination.

  Examples of triazine ultraviolet absorbers include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4-[( 2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2- Hydroxy-3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethyl) Phenyl) -6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine and the like, and mixtures, modified products, polymers, and derivatives thereof.

The amount of the UV absorber is 3 to 200 parts by weight, preferably about 5 to 100 parts by weight with respect to 100 parts by weight of the resin, although it depends on the UV absorbing ability of the UV absorber and the compatibility with the resin. Let
When the addition amount is less than 3 parts by weight, there may be a case where sufficient ultraviolet absorbing ability cannot be exhibited in the heat transferable protective layer. Moreover, when it exceeds 200 parts by weight, the cohesive force in the layer is also affected, and the toughness of the resin layer may be reduced, transparency may be lost, or blocking may occur.
In addition, some ultraviolet absorbers contribute to the provision of ozone resistance, and the amount of addition can be appropriately determined from the viewpoint of protecting the adhesive layer itself and protecting the image.

  In addition to the ultraviolet absorber, a hindered amine light stabilizer can also be added. Examples of hindered amine light stabilizers include dimethyl succinate 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, poly [{6- (1,1,3, 3-tetramethylbutyl) amino-1,3,5-triazine-2,4diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6 6-tetramethyl-4-piperidyl) imino}], N, N′-bis (3-aminopropyl) ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2,6,6- Pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3,5-di-t- Butyl-4-hydroxybenze ) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl), tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2, Examples include 3,4-butanetetracarboxylate.

  As an example of the present invention, the three-layer configuration has been described as described above, but more than that may be used. The binder resin for the release layer, the adhesive layer, and the intermediate layer need not be the same, and different resins can be used in combination depending on the function, or partially different resins can be laminated. In addition, it is preferable to appropriately consider the residual solvent after drying when forming the release layer and the adhesive layer.

The present invention is a thermal transfer sheet provided with two or more protective layers on a substrate sheet. As described above, one of the thermal transfer sheets is provided with a layer containing an ultraviolet absorber just above a printing screen. Since the color fading and disassembly from the part do not occur, the printed matter can be protected for a longer period.
Once the color decomposition starts, the chain reaction causes the decomposition reaction to be continued and promoted. If the stop reaction is not exceeded, the color fading and decomposition do not stop, so the anti-fading effect by the protective layer is very large.
Also, even if a child such as an infant or a pet licks the surface by any chance, no harmful components such as UV absorbers are present on the surface, so that the physical effects can be minimized.

  In addition, as a method for forming the thermal transfer ink layer, the release layer, the release layer, and the adhesive layer, any known thin film forming method that can be applied separately such as a gravure coating method and a slot coating method can be adopted. It can be formed by applying a thin film with a coating solution and drying it.

Example 1
Hereinafter, it explains in full detail based on an Example.
First, as the base sheet 1, a polyethylene terephthalate film (diamond foil: manufactured by Mitsubishi Chemical Polyester Film) with a thickness of 5 μm and an easy adhesion treatment was used. Then, 100 parts by weight of polyester polyol resin, 10 parts by weight of isocyanate curing agent (Takenate: manufactured by Mitsui Chemicals Polyurethane), and 1 part by weight of lubricant (phosphate ester: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) are used as materials for the heat-resistant slip layer 2. A coating agent was prepared by dissolving in a mixed solvent consisting of 36 parts by weight of methyl ethyl ketone and 36 parts by weight of toluene. The prepared coating agent was formed on the surface of the base sheet 1 on the non-adhesive side so as to have a dry film thickness of 1.0 μm by gravure coating to obtain a heat resistant slipping layer 2.

  The heat-sensitive ink layer 3 (yellow) is C.I. I. 3.0 parts by weight of Solvent Yellow 93, C.I. I. Transfer yellow ink by dissolving 1.0 part by weight of Solvent Yellow 16 and 5.0 parts by weight of polyvinyl acetal resin (Denka Butyral: manufactured by Denki Kagaku Kogyo Co., Ltd.) in a mixed solvent consisting of 45 parts by weight of methyl ethyl ketone and 45 parts by weight of toluene. A layer (yellow) coating solution was prepared.

  The heat-sensitive ink layer 4 (magenta) is C.I. I. 1.5 parts by weight of disperse thread 60, C.I. I. Disperse violet 26 and 1.5 parts by weight of polyvinyl acetal resin (Denka Butyral: manufactured by Denki Kagaku Kogyo Co., Ltd.) were used, and dissolved in a mixed solvent consisting of 46 parts by weight of methyl ethyl ketone and 46 parts by weight of toluene, thereby allowing transferability. An ink layer (magenta) coating solution was prepared.

  The heat-sensitive ink layer 5 (cyan) is C.I. I. 1.5 parts by weight of Solvent Blue 63, C.I. I. A transferable ink layer prepared by dissolving 1.5 parts by weight of Solvent Blue 36 and 5.0 parts by weight of polyvinyl acetal resin (Denka Butyral: electrochemical industrial property) and dissolving it in a mixed solvent consisting of 46 parts by weight of methyl ethyl ketone and 46 parts by weight of toluene. A (cyan) release layer coating solution was prepared.

As the release layer 6, 5 parts by weight of cellulose acetate resin (manufactured by Daicel Chemical Industries), 0.5 part by weight of polyester resin, dissolved in a mixed solution of 89.7 parts by weight of methyl ethyl ketone and 5 parts by weight of cyclohexanone, A release layer coating solution was prepared.

  For the release layer 9, 100 parts by weight of an acrylic resin (Dianar: manufactured by Mitsubishi Rayon) was used and dissolved in a mixed solvent consisting of 50 parts by weight of methyl ethyl ketone and 50 parts by weight of toluene to prepare a coating solution for the release layer.

  Adhesive layer 10 comprises acrylic resin: 100 parts of resin having a weight average molecular weight of 250,000, benzotriazole UV absorber: 20 parts by weight of weight average molecular weight: 510, 1 part by weight of a hindered amine light stabilizer, and a thermal antioxidant. One part was used and dissolved in a mixed solvent consisting of 50 parts by weight of methyl ethyl ketone and 50 parts by weight of toluene to prepare a coating solution for an adhesive layer.

  The coating liquid prepared as described above is applied to the surface of the base sheet 1 on the easy-adhesion side by a gravure coating method, the thermal transfer ink layer 3 (yellow), the thermal transfer ink layer 4 (magenta), and the thermal transfer ink layer 5. (Cyan) is formed in a surface sequence with a dry film thickness of 1.0 μm, and then a release layer 6 is formed in a surface sequence with a dry film thickness of 0.1 μm using a release layer forming coating solution. After forming the release layer 9 with a dry film thickness of 0.5 μm on the release layer 6 using the release layer coating solution, the adhesive layer coating solution is subsequently applied on the release layer 9. Then, the adhesive layer 10 was formed with a dry film thickness of 3.0 μm to produce the thermal transfer sheet of the present invention.

(Example 2)
The release layer 9 was formed in the same manner as in Example 1 above, and the adhesive layer 10 was further coated with 20 parts by weight of acrylic resin: weight average molecular weight: 350,000 resin and UV absorber: weight average molecular weight: 850, hindered amine. A coating solution for an adhesive layer was prepared by dissolving 1 part by weight of a light stabilizer and 1 part of a thermal antioxidant in a mixed solvent consisting of 50 parts by weight of methyl ethyl ketone and 50 parts by weight of toluene.

(Comparative Example 1)
The release layer 9 was formed in the same manner as in Example 1 above, and the adhesive layer 10 was further coated with 20 parts by weight of acrylic resin: weight average molecular weight: 350,000 resin and UV absorber: weight average molecular weight: 192, hindered amine. A coating solution for an adhesive layer was prepared by dissolving 1 part by weight of a light stabilizer and 1 part of a thermal antioxidant in a mixed solvent consisting of 50 parts by weight of methyl ethyl ketone and 50 parts by weight of toluene.

(Comparative Example 2)
The release layer 9 is formed in the same manner as in Example 1 above, and the adhesive layer 10 is formed thereon with an acrylic resin: weight average molecular weight: 8000 resin and an ultraviolet absorber: weight average molecular weight: 850, 20 parts by weight, hindered amine A coating solution for an adhesive layer was prepared by dissolving 1 part by weight of a light stabilizer and 1 part of a thermal antioxidant in a mixed solvent consisting of 50 parts by weight of methyl ethyl ketone and 50 parts by weight of toluene.

(Performance comparison) The thermal transfer sheets prepared in the above examples and comparative examples were subjected to performance comparison evaluation according to the following procedure.
(1) Adhesiveness Regarding the transfer-related layers (3 layers: release layer, release layer, adhesive layer) of the thermal transfer sheet prepared in Examples 1 and 2 and Comparative Examples 1 and 2, the temperature is 40 ° C. and the humidity is 65%. Stored under 14 days. Then, cello tape (registered trademark) (manufactured by Nichiban Co., Ltd., 25 mm width) was laminated on the transfer-related layer before and after storage with a rubber roller at room temperature, and after 5 minutes, it was peeled upward by 180 degrees with a peeling tester. Peeling (Orientec, peel speed: 30 mm / min, 25 mm width) was performed, and peel strength was measured.
Evaluation judgment:
○: The peel strength after storage is 95% or more of the peel strength before storage.
X: The peel strength after storage is less than 95% of the peel strength before storage.

(2) Light resistance The thermal transfer sheet produced in Examples 1 and 2 and Comparative Examples 1 and 2 was a thermal transfer printer sufficiently placed at room temperature (23 ° C., 50%), and a thermal ink layer Y (yellow), M (magenta), C (cyan), and transfer related layers (3 layers: release layer, release layer, adhesive layer) were sequentially printed on the entire screen, and solid black was printed. The printed matter was irradiated for 240 hours at BP 63 ° C. with a xenon weather meter (400 mJ / cm 2), and the difference in reflection density before and after the light resistance test was measured with a Macbeth reflection densitometer for an initial value OD = 1.0. It was measured.
Evaluation judgment:
○: The decrease in OD value after light resistance test is less than 0.2. The value in () is OD value. ×: The decrease in OD value after light resistance test is 0.2 or more.

(3) Gloss Using the thermal transfer printer prepared in Examples 1 and 2 and Comparative Examples 1 and 2 with the thermal transfer printer sufficiently placed at room temperature (23 ° C., 50%), the thermal ink layer Y (yellow), M (Magenta), C (cyan), transfer-related layers (3 layers: release layer, release layer, adhesive layer) were sequentially printed in full screen, and solid black was printed. The printed product was measured for 60-degree reflection gloss with a surface gloss meter (manufactured by HORIOBA), and then the gloss after storage for 7 days in an environment of 40 ° C. and 65% was also measured.
Evaluation judgment:
○: Gloss difference (initial gloss value-gloss value after storage) is less than ± 1.0 ×: Gloss difference (initial gloss value-gloss value after storage) is ± 1.0 or more

(4) UV absorber persistence (surface existence)
The transfer related layers (3 layers: release layer, release layer, adhesive layer) of the heat transferable sheet prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were transferred to a PET film having a thickness of 25 μm with a heating roll, A thermal transfer sheet having a configuration of PET, an adhesive layer and a release layer was formed. In the thermal transferable sheet, spectral absorption is measured by transmission with a spectrophotometer (manufactured by Hitachi, Ltd.), and an absorption peak value of 354 nm is obtained. Then, after storing for 7 days in an environment of 40 ° C. and 65%, the surface of the release layer was reciprocated 5 times with a dry Kimwipe, and the ultraviolet absorber that had been exposed on the surface was wiped off, and spectroscopic measurement was performed again.
Evaluation judgment:
○: The absorption peak value at 354 nm is kept higher than 95% of the absorption peak value before storage.
X: The absorption peak value of 354 nm is 95% or less of the absorption peak value before storage.

Table 1 below shows the performance comparison evaluation results.

  The thermal transfer sheet of the present invention can be used in a thermal transfer sheet having a layer for protecting an image formed by various image recording apparatuses, particularly an image using a dye.

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Heat-resistant slip layer 3 ... Heat-sensitive ink layer (yellow)
4 ... Heat-sensitive ink layer (magenta)
5 ... Heat-sensitive ink layer (cyan)
6 ... Release layer 7 ... Transfer related layer 8 ... Transferable protective layer 9 ... Release layer
10: Adhesive layer

Claims (3)

  A thermal transferable sheet comprising two or more transferable protective layers on at least a part of one surface of a base sheet, and an ultraviolet absorber contained in the outermost layer of the transferable protective layer.   In the transferable protective layer containing the ultraviolet absorber, the ratio P between the weight average molecular weight WB of the binder resin contained in the transferable protective layer and the weight average molecular weight wu of the ultraviolet absorber contained in the transferable protective layer. 2. The thermal transferable sheet according to claim 1, wherein (P = WB / wu) is in a range of 12 ≦ P ≦ 1300.   An image formed on a transfer medium and two or more transfer protection layers formed to cover at least a part of the image, wherein the transfer protection layer is the claim 1 or the claim. A printed matter, which is formed using the thermal transfer sheet described in 2.