JP4456548B2 - Sublimation type thermal transfer sheet - Google Patents

Description

  The present invention relates to a sublimation thermal transfer sheet used for printing by a sublimation thermal transfer system.

  Conventionally, various thermal transfer methods are known. Among them, a dye transfer layer containing a sublimation dye can be supported on a sheet of paper or plastic film, and can be dyed on the surface of paper or plastic film. There have been proposed methods for forming various full-color images on a sublimation thermal transfer image-receiving sheet provided with a receiving layer. Since this method uses a sublimation dye as a color material, the density gradation can be freely adjusted and a full color image of an original can be expressed. In addition, the image formed with the dye is very clear and excellent in transparency, so it is excellent in intermediate color reproducibility and gradation reproducibility, and can form high-quality images comparable to silver salt photographs. Is possible.

  Here, the dye transfer layer and the storage stability of the dye transfer layer of the sublimation thermal transfer sheet are required. That is, the sublimation dye contained in the dye transfer layer is well held by the binder during storage of the sublimation thermal transfer sheet, and the sublimation dye is required to be released from the binder during printing. ing. Conventionally, an acetal-based resin has been used as a binder in such a dye transfer layer. However, the acetal resin is excellent in dye retention during storage, but has a problem of low sensitivity during dye transfer.

  Therefore, in order to solve such a problem, for example, a method of changing the ratio of the sublimation dye to the resin in the dye transfer layer is considered. However, when the amount of the sublimation dye is increased, the sublimation is performed. When the mold thermal transfer sheet is stored in a wound state, there has been a problem that the sublimation dye oozes out and moves to a dye transfer layer or a protective layer of another color. Further, when the amount of the resin is increased, there is a problem in that the printing sensitivity is lowered because the dye content in the dye transfer layer is reduced.

  Therefore, it is desired to provide a sublimation type thermal transfer sheet having a dye transfer layer that has excellent storage stability and high dye transfer sensitivity.

  In order to solve the above-mentioned problems, the present invention is a sublimation type thermal transfer sheet having a base material and a dye transfer layer formed on the base material and having dye transfer properties, wherein the dye transfer layer has a sublimation type. Provided is a sublimation type thermal transfer sheet comprising a dye, an ultraviolet curable resin, and a photopolymerization initiator.

  According to the present invention, since the dye transfer layer contains an ultraviolet curable resin, the dye transfer layer can have high heat resistance, and at the time of printing, the image receiving sheet, the dye transfer layer, Can be prevented from being thermally fused. Moreover, the said ultraviolet curable resin shall have a network structure bridge | crosslinked with high density by the effect | action of the photoinitiator contained in the said dye transfer layer. Therefore, during storage, the sublimation dye is well held by the UV curable resin, and only when heat is applied during printing, the mesh spreads and the sublimation dye is released from the dye transfer layer. can do. Therefore, according to this invention, it can be set as the high quality sublimation type thermal transfer sheet excellent in preservability and dye transferability.

  In the above invention, the ultraviolet curable resin is preferably a photosensitive cellulose resin. In particular, the photosensitive cellulose resin is represented by the hydroxyl group of cellulose or a cellulose derivative, and the following formula (1). A modified cellulose resin obtained by reacting an isocyanate group of a compound to be produced is preferable.

Here, in the above formula, ^{R 1} represents -H or -CH _3; ^{R 2} represents an alkylene group having 1 to 5 carbon atoms which may have an alkyl group in a side chain.

  This is because the heat resistance of the dye transfer layer is high and the dye retention and dye transfer properties can be further improved.

  According to the present invention, it is possible to prevent the image receiving sheet and the dye transfer layer from being thermally fused during printing. Furthermore, it is possible to obtain a high-quality sublimation thermal transfer sheet excellent in storage stability and dye transfer property.

  The present invention relates to a sublimation thermal transfer sheet used for printing by a sublimation thermal transfer system. This will be described in detail below.

  The sublimation type thermal transfer sheet of the present invention is a sublimation type thermal transfer sheet having a base material and a dye transfer layer formed on the base material and having dye transfer properties, and the dye transfer layer includes a sublimation dye and And an ultraviolet curable resin and a photopolymerization initiator.

  The sublimation thermal transfer sheet of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a sublimation type thermal transfer sheet of the present invention. As illustrated in FIG. 1, a sublimation thermal transfer sheet 3 of the present invention includes a base material 1 and a dye transfer layer 2 having dye transfer properties formed on the base material 1.

  In addition, the sublimation type thermal transfer sheet of the present invention has a printing apparatus in a state where the dye transfer layer 2 of the sublimation type thermal transfer sheet 3 and the receiving layer 12 of the image receiving sheet 11 face each other as shown in FIG. By applying heat from the thermal head 13, the sublimation dye sublimated from the dye transfer layer 2 moves to the receiving layer 12, and an image is printed on the image receiving sheet 11.

  Here, when the heat resistance of the dye transfer layer of the sublimation thermal transfer sheet is low, the dye transfer layer and the receiving layer of the image receiving sheet are thermally fused by heat from the thermal head, and the image receiving sheet. It is difficult to print well. However, in the present invention, since an ultraviolet curable resin and a photopolymerization initiator are used for the dye transfer layer of the sublimation thermal transfer sheet, the crosslink density of the resin in the dye transfer layer is high. And can be excellent in heat resistance. Therefore, when printing on a sublimation type thermal transfer image receiving sheet by the sublimation type thermal transfer method, the dye transfer layer and the receiving layer of the image receiving sheet are not thermally fused by heat applied from the thermal head. It can be.

  Moreover, the said ultraviolet curable resin can form the network structure bridge | crosslinked with high density by the effect | action of the photoinitiator contained in a dye transfer layer. Therefore, at the time of storage of the sublimation type thermal transfer sheet, the sublimation type dye can be held inside the network structure, and can be hardly released from the dye transfer layer. Further, since the network structure of the ultraviolet curable resin is expanded by heat applied during printing, the sublimation dye held inside the network can be easily released from the dye transfer layer during printing. Therefore, according to the present invention, a high-quality sublimation thermal transfer sheet excellent in dye transfer property and storage stability can be obtained.

Furthermore, in the present invention, a photosensitive cellulose resin is preferably used as the ultraviolet curable resin. Conventionally, when a cellulose-based resin is used as a binder for a dye layer, it has been known that sensitivity and storage stability are good, but along with the recent increase in the printing speed, the temperature of the thermal head has increased, Since heat fusion with the receiving layer occurs, problems such as a decrease in printing density due to suppression of the amount of dye used have occurred.
However, in the present invention, it is possible to improve the transfer sensitivity of the dye layer by using a photosensitive cellulose resin having ultraviolet curability among cellulose resins. In the present invention, by using the photosensitive cellulose resin, such an effect can be expressed because, even if a high temperature is applied by photocuring, it is not thermally fused to the image receiving layer, and the expansion / contraction action of the network structure, etc. This is probably because the dye is selectively released only when heat is applied, which leads to an improvement in sensitivity.

  The sublimation type thermal transfer sheet of the present invention has a substrate and a dye transfer layer formed on the substrate. Hereinafter, each structure of the sublimation type thermal transfer sheet of the present invention will be described in detail.

1. Dye transfer layer First, the dye transfer layer used for the dye transfer layer used for the sublimation type thermal transfer sheet of the present invention will be described. The dye transfer layer used in the present invention is formed on a substrate to be described later, contains a sublimation dye, an ultraviolet curable resin, and a photopolymerization initiator, and has dye transferability. is there. The dye transfer layer may be one in which a dye transfer layer having a specific hue is formed on the entire surface of the substrate. For example, a plurality of dye transfer layers containing sublimation dyes having different hues may be formed on the substrate. May be formed respectively.
Hereinafter, the ultraviolet curable resin, the photopolymerization initiator, and the sublimation dye used in the dye transfer layer will be described.

(UV curable resin)
First, the ultraviolet curable resin used in the present invention will be described. In the present invention, the dye transfer layer contains an ultraviolet curable resin, but the dye transfer layer contains an ultraviolet curable resin, the ultraviolet curable resin described later is the main component of the dye transfer layer. It is said to be a component, and includes the case where the ultraviolet curable resin is crosslinked by ultraviolet irradiation.

  The ultraviolet curable resin is not particularly limited as long as it has a dye holding property for holding a sublimation dye and a dye transfer property for transferring a sublimation dye, which will be described later, and can be cured by ultraviolet rays. is not. As such an ultraviolet curable resin, it is preferable to form a network structure by ultraviolet irradiation.

  The ultraviolet curable resin used in the present invention preferably has a softening point in the range of 50 ° C to 300 ° C, and more preferably in the range of 80 ° C to 250 ° C. This is because the heat resistance of the dye transfer layer can be increased, and the image receiving sheet and the dye transfer layer can be prevented from being thermally fused during printing. In addition, the said softening point is obtained from the result measured by a temperature rising rate; 3 degree-C / min with a rigid pendulum type surface physical property tester (RPT3000W by A & D), or the result is made into a graph.

  Examples of such ultraviolet curable resins include unsaturated polyesters, polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, polyol (meth) acrylates, melamine (meth) acrylates and the like (meta ) Acrylate, photosensitive cellulose resin, and the like. These may be used alone or in combination of two or more.

  In the present invention, among the above, the ultraviolet curable resin is preferably a photosensitive cellulose resin, and in particular, a hydroxyl group of cellulose or a cellulose derivative and a compound represented by the following formula (1): A modified cellulose resin obtained by reacting with an isocyanate group is preferable. This is because the heat resistance of the dye transfer layer is high and the dye retention and dye transfer properties can be further improved.

Here, in the above formula, ^{R 1} represents -H or -CH _3; ^{R 2} represents an alkylene group having 1 to 5 carbon atoms which may have an alkyl group in a side chain.

  Examples of the reaction method of the residual hydroxyl group of the cellulose or cellulose derivative and the isocyanate group of the compound represented by the formula (1) include organic metal catalysts (for example, organic tin compounds), and catalysts such as organic amine catalysts. In the presence of the above, there may be mentioned a method in which the compound (1) and cellulose or cellulose derivative are put in a reaction vessel and synthesized at a temperature of 60 to 90 ° C. and a reaction time of 2 to 24 hours.

Moreover, the reaction ratio of the hydroxyl group in the said cellulose or a cellulose derivative and the isocyanate group of the compound represented by said Formula (1) is 0.1-0.8 equivalent of isocyanate groups with respect to 1 equivalent of said hydroxyl groups. A range is preferable, and a range of 0.2 to 0.6 equivalent is more preferable. If it is less than 0.1 equivalent, it is not preferable because the photocurability is lowered. On the other hand, if it exceeds 0.8 equivalent, the storage stability may be lowered.
The hydroxyl group includes a modified hydroxyl group. That is, for example, in the cellulose derivative, the case where the hydroxyl group of cellulose is etherified is also included.

  Examples of the cellulose or cellulose derivative used for obtaining the modified cellulose resin include cellulose, methyl cellulose, ethyl cellulose, propyl cellulose, cellulose acetate, and cellulose butyrate.

In the compound represented by the above formula (1), specific examples of R ² include methylene group, ethylene group, propylene group, isopropylene group, butylene group, t-butylene group, and pentylene group. Of these, an ethylene group is particularly preferable.

  Specific examples of the compound represented by the formula (1) include acryloyloxyethylene isocyanate, acryloyloxypropylene isocyanate, acryloyloxyisopropylene isocyanate, acryloyloxybutylene isocyanate, methacryloyloxyethylene isocyanate, methacryloyloxypropylene isocyanate, Examples include methacryloyloxyisopropylene isocyanate and methacryloyloxybutylene isocyanate. Among them, a modified cellulose resin using methacryloyloxyethylene isocyanate has very high flexibility and can be preferably used.

  In this invention, 1 type (s) or 2 or more types can be used as a compound represented by the said Formula (1).

The weight average molecular weight of the modified cellulose resin used in the present invention is preferably 10,000 to 500,000, more preferably 30,000 to 300,000, and particularly preferably 50,000 to 300,000. If the molecular weight is less than 10,000, the releasability may be deteriorated. On the other hand, if the molecular weight exceeds 500,000, the viscosity increases, which is not preferable in production.
Here, the weight average molecular weight of the modified cellulose resin can be measured using, for example, GEL PERMEATION CHROMATOGRAPH HLC-8020 manufactured by Tosoh Corporation.

  In the present invention, modified cellulose resins having different molecular weights may be mixed and used.

As the ultraviolet curable resin used in the present invention, a mixture of the ultraviolet curable resin and another thermoplastic resin may be used. Examples of the other thermoplastic resins used in the present invention include, for example, vinyl resins such as polyacrylic ester, polystyrene, and polystyrene acrylic, various saturated and unsaturated polyester resins, polycarbonate resins, polycaprolactone resins, and polyolefin resins. Examples thereof include resins, polyamide resins such as urea resin, melamine resin, and benzoguanamine resin.
In the present invention, only one kind may be used as the other thermoplastic resin, or two or more kinds may be mixed and used.

  When a mixture of the ultraviolet curable resin and the other thermoplastic resin is used as the ultraviolet curable resin, the content of the other thermoplastic resin is based on 100 parts by weight of the ultraviolet curable resin. The amount is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and particularly preferably 20 parts by weight or less.

(Photopolymerization initiator)
The photopolymerization initiator used in the present invention will be described. As the photopolymerization initiator used in the present invention, various photosensitizers that are generally used as photosensitizers for ultraviolet curable paints can be used. Examples of such photopolymerization initiators include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, α-methylbenzoin, and α-phenylbenzoin; anthraquinone compounds such as anthraquinone and methylanthraquinone Benzyl: diacetyl; phenyl ketone compounds such as acetophenone and benzophenone; sulfide compounds such as diphenyl disulfide and tetramethylthiuram sulfide; α-chloromethylnaphthalene; halogenated hydrocarbons such as anthracene, hexachlorobutadiene and pentachlorobutadiene; .

  The content of the photopolymerization initiator in the dye transfer layer in the present invention is not particularly limited, but is usually in the range of about 0.5 to 10 parts by weight per 100 parts by weight of the ultraviolet curable resin.

(Sublimation dye)
Next, the sublimation dye used in the present invention will be described. The sublimation dye used in the present invention is not particularly limited as long as it is held by the ultraviolet curable resin and is transferred to the image receiving sheet and exhibits good color development. Such a sublimation dye is appropriately selected according to the hue of the sublimation transfer layer, the type of the sublimation thermal transfer sheet, the type of the ultraviolet curable resin, and the like. For example, diarylmethane, triarylmethane, and thiazole , Methocyanines such as merocyanine, pyrazolone methine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazolazomethine, azomethine typified by imidazoazomethine, pyridone azomethine, xanthene, oxazine, dicyanostyrene, tricyanostyrene Representative cyanomethylene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrrolazo, pyralazo, imidazoleazo, thiadiazoleazo, triazoleazo, diz Azo-based, such as a zone, spiropyran, India Linos Piropi run system, fluoran, rhodamine lactam, naphthoquinone, anthraquinone, and a dye quinophthalone system, and the like.

  In the present invention, when the mass of the resin component contained in the dye transfer layer (the UV curable resin, the diluting reactant described later, etc.) is 1, the dye is 0.1 to 3.5. In particular, it is preferably contained in an amount of about 0.3 to 3.0, particularly about 0.5 to 2.5.

(Other)
For the dye transfer layer, in addition to the ultraviolet curable resin, photopolymerization initiator and sublimation dye, for example, to adjust the crosslinking density of the dye transfer layer, a general thermoplastic resin, acrylic Reactive diluents such as other monofunctional or polyfunctional monomers and oligomers may be used.

  In the present invention, it is particularly preferred that a monomer having crystallinity is used together with the ultraviolet curable resin. When the monomer having crystallinity is used, the crystalline monomer is contained in the network structure constituted by the ultraviolet curable resin. Therefore, when heat is applied to the dye transfer layer at the time of printing, the crystalline monomer expands, and the network having the network structure is expanded. This is because the sublimation dye can be easily released from the network structure of the ultraviolet curable resin, and the dye transfer property of the dye transfer layer can be further improved.

  Examples of such highly crystalline monomers include caprolactone-modified monomers, such as KAYARAD HX-220, HX-620, DPCA-20, DPCA-30, DPCA-60, DPCA-120 manufactured by Nippon Kayaku Co., Ltd. (All are trade names), Daicel UCB's Ebecryl 2047 (trade name), Daicel Chemical Industries, Inc. PLACEL FM, FA series (trade names), and the like.

  The monomer having high crystallinity is in the range of 0.05 to 1.0, particularly in the range of 0.1 to 0.6, assuming that the amount (mass) of the ultraviolet curable resin contained in the dye transfer layer is 1. It is preferable that it is contained. This is because the dye transfer property can be improved.

  The dye transfer layer may contain a release agent. By adding a release agent, it is possible to further prevent thermal fusion between the receiving layer and the dye transfer layer during printing. Examples of the mold release agent include silicone-based surfactants and fluorine-based surfactants. The silicone-based surfactant is a compound in which a hydrophobic part is made of a silicone resin, and a hydrophilic group is introduced into the terminal and / or side chain thereof. Typical examples of the silicone resin include poly (dimethyl) siloxane, methylphenyldimethylpolysiloxane, tetramethyltetraphenylpolysiloxane, dimethylpolysiloxane / polymethylphenylsiloxane copolymer, polymethylsiloxane, tetramethylpolymethylsiloxane, Examples thereof include polymethylsiloxane / polydimethylsiloxane copolymer in which a part or all of the side chain methyl groups are substituted with phenyl groups or hydrogen atoms. Examples of the hydrophilic group introduced into the silicone resin include a polyether group, a polyglycerin group, a pyrrolidone group, a betaine group, a sulfate group, a hydroxyl group, a carboxyl group, a phosphate group, and a quaternary ammonium base.

  The hydrophilic groups introduced into these silicone resins can be used in appropriate combination. In addition, regarding the structure of the surfactant, not only a hydrophilic group is simply introduced into the terminal and / or side chain of the above-mentioned silicone resin, but also a polymer having a hydrophilic group introduced therein and a polymer having no hydrophilic group introduced therein are randomly copolymerized, blocked It may be copolymerized by copolymerization. Among these, a silicone surfactant into which polydimethylsiloxane is introduced as a silicone resin and a polyether group, polyglycerin group, or pyrrolidone group is introduced as a hydrophilic group is preferably used.

  The release agent is preferably contained in the solid content of the dye transfer layer excluding the dye in an amount of about 1% by mass to 10% by mass, especially about 3% by mass to 7% by mass.

  The dye transfer layer may contain a thermal polymerization inhibitor, a plasticizer, a surfactant, an antifoaming agent, and other additives as necessary. Here, examples of the thermal polymerization inhibitor include hydroquinone, hydroquinone monoethyl ether, p-methoxyphenol, pyrogallol, catechol, 2,6-di-tert-butyl-p-cresol, β-naphthol and the like. Examples of the plasticizer include dioctyl phthalate, didodecyl phthalate, triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl sebacate, and triacetyl glycerin. Examples of the surfactant include various anionic, cationic, and nonionic surfactants. Furthermore, as said antifoamer, various antifoamers, such as a silicone type and a fluorine type, are mentioned, for example.

  Examples of the other additive include organic fine particles such as polyethylene wax for improving the releasability from the image receiving sheet and the coating suitability of the dye transfer layer forming composition used for forming the dye transfer layer. Inorganic fine particles are exemplified.

(Method of forming dye transfer layer)
As a method for forming the dye transfer layer as described above, the sublimation dye, the photopolymerization initiator and the ultraviolet curable resin, and the additives described above are usually added in a solvent, and each component is dissolved or dispersed. To prepare a dye transfer layer forming composition. Thereafter, the composition for forming a dye transfer layer can be formed by irradiating with radiation after being applied onto a substrate described later and dried. As this coating method, known means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, or the like can be used. The dye transfer layer formed in this way has a dry coating amount of 0.2 to 6.0 g / m ² , preferably about 0.3 to 2.0 g / m ² .

  About the ultraviolet-ray used for hardening of the said composition for dye transfer layer formation, it can be made to be the same as that used for hardening of a general ultraviolet curable resin.

  In addition, the solvent used in the dye transfer layer forming composition is not particularly limited as long as it is an organic solvent that dissolves the ultraviolet curable resin as described above. In consideration of aromatic solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and cyclohexanone, and cellosolve organic solvents such as methyl cellosolve and ethyl cellosolve. A mixed solvent comprising a solvent is preferably used. Although the solid content concentration of the ultraviolet curable resin in the dye transfer layer forming composition is not particularly limited, it is generally preferably in the range of 1% by mass to 50% by mass.

  Further, a solvent may be added to the above composition for forming a dye transfer layer in order to improve coatability. Such solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, propylene glycol monomethyl ether, propylene Glycol monoethyl ether, propylene glycol monopropyl ether, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, tetrahydrofuran, cyclohexanone, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, 2-hydroxy Methyl propionate, 2 Ethyl hydroxypropionate, 2-hydroxy-2-methyl, methyl-3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, ethyl-3-propoxypropionate, propyl -3-methoxypropionate, methyl acetoacetate, ethyl acetoacetate, benzyl methyl ether, benzyl ethyl ether, dihexyl ether, ethyl acetate, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, benzene , Toluene, xylene, cyclohexanone, methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, glycerin and the like.

2. Next, the base material used for the sublimation type thermal transfer sheet of the present invention will be described. The substrate used in the present invention is not particularly limited as long as it can form the dye transfer layer and has predetermined heat resistance and strength. Examples of such a substrate include, for example, a polyethylene terephthalate film, a 1,4-polycyclohexylenedimethylene terephthalate film, a polyethylene naphthalate film, and a polyphenylene sulfide having a thickness of about 0.5 to 50 μm, preferably about 1 to 10 μm. Film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film, etc. are used. .

  The substrate may be subjected to an adhesion treatment on the surface on which the dye transfer layer is formed. Thereby, the wettability and adhesiveness of the composition for forming a dye transfer layer described above can be improved. As the adhesion treatment method, known resins such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, primer treatment, grafting treatment, etc. Surface modification techniques can be applied. Two or more of the above treatments may be used in combination.

  The primer treatment may be performed, for example, by applying a primer solution to an unstretched film at the time of film formation by melt extrusion of the plastic film and then stretching the plastic film.

  Moreover, you may form an easily bonding layer in the surface by which the dye transfer layer is formed as said adhesion process. The easy-adhesion layer is, for example, a polyester resin, a polyacrylate ester resin, a polyvinyl acetate resin, a polyurethane resin, a styrene acrylate resin, a polyacrylamide resin, a polyamide resin, a polyether resin, or a polystyrene resin. A layer formed using a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a vinyl resin such as polyvinyl pyrrolidone, a polyvinyl acetal resin such as polyvinyl acetoacetal or polyvinyl butyral, and the like. it can.

3. Sublimation type thermal transfer sheet The sublimation type thermal transfer sheet of the present invention is not particularly limited as long as it has the substrate and the dye transfer layer. For example, the dye transfer layer is formed on the substrate. In addition, a protective layer or the like may be formed. In addition, a heat-resistant slipping layer or the like is formed on the surface of the substrate opposite to the side where the dye transfer layer is formed in order to prevent adverse effects such as sticking or printing wrinkles due to the heat of the thermal head. There may be.

  Here, the image receiving sheet on which an image is printed by the sublimation type thermal transfer sheet of the present invention is not particularly limited, and may be the same as that used in printing by general sublimation type transfer. . In the present invention, it is particularly preferable to use an image receiving sheet having a receiving layer that does not contain the same type of resin as the ultraviolet curable resin used in the dye transfer layer. This is because if an image receiving sheet containing the same type of resin as the ultraviolet curable resin used for the dye transfer layer is used for the receiving layer, the dye transfer layer and the receiving layer may be thermally fused. As the image receiving sheet on which an image is printed by the sublimation type thermal transfer sheet of the present invention, for example, a sheet having a receiving layer containing a radiation curable resin, a thermoplastic resin or the like is used.

  Examples of the radiation curable resin include various polyesters such as unsaturated polyesters, polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, polyol (meth) acrylates, and melamine (meth) acrylates. Etc. can be illustrated.

  Examples of the thermoplastic resin include polyolefin resins such as polypropylene; halogenated polymers such as polyvinyl chloride and polyvinylidene chloride; vinyl polymers such as polyvinyl acetate, polyacrylic ester and polyvinyl acetal; polyethylene terephthalate, poly Polyester resins such as butylene terephthalate; polystyrene resins; polyamide resins; copolymer resins of olefins such as ethylene and propylene and other vinyl polymers; cellulose resins such as ionomers and cellulose diacetates, polycarbonates, etc. Can do.

  As the resin contained in the receiving layer, two or more kinds of the radiation curable resin or the thermoplastic resin may be mixed and used. The radiation curable resin and the thermoplastic resin may be used in combination.

  In the present invention, it is preferable that a heat-resistant slipping layer is formed on the surface of the substrate opposite to the side where the dye transfer layer is formed. Hereinafter, such a heat resistant slipping layer will be described. The resin for forming the heat-resistant slipping layer may be a conventionally known resin, such as polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin. , Styrene-butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetate propionate resin, cellulose acetate butyrate Rate resin, cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, polycarbonate Boneto resins, and chlorinated polyolefin resins.

  The slipperiness imparting agent added to or overcoating the heat resistant slipping layer made of these resins includes phosphate ester, silicone oil, graphite powder, silicone graft polymer, fluorine graft polymer, acrylic silicone graft polymer, acrylic siloxane, aryl Silicone polymers such as siloxane may be mentioned, but it is preferable to use a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound, and a phosphate ester compound. Further, it is more preferable to add a filler.

The heat resistant slipping layer is prepared by dissolving or dispersing the above-described resin, slipperiness-imparting agent, and filler with a suitable solvent on the base material to prepare a heat resistant slipping layer forming coating solution. Can be formed by coating with a forming means such as gravure printing, screen printing, reverse roll coating using a gravure plate, and drying. The coating amount of the heat-resistant slip layer is a solid, it is preferably a ^{0.1g / m 2 ~3.0g / m 2} .

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. In the examples, “part” or “%” is based on weight unless otherwise specified.

(Production Example 1)
Into a four-necked flask equipped with a thermometer, stirrer, dropping funnel and condenser, 3 g of cellulose acetate (trade name: L-20 manufactured by Daicel Chemical Industries) was added, 97 g of methyl ethyl ketone (hereinafter, MEK) was added, and 50 Dissolved at ° C. Subsequently, 1.25 g of methacryloyloxyethylene isocyanate (trade name Karenz MOI, manufactured by Showa Denko KK) was sequentially dropped, and after the dropwise addition, a heating reaction was performed at 60 ° C. to obtain a modified cellulose resin 1. The reaction was completed by measuring the amount of isocyanate in the reaction solution by back titration analysis and confirming that 90% or more of the charged isocyanate had reacted.

(Production Example 2)
In the same manner as in Production Example 1, 2.5 g of cellulose acetate (trade name: L-50 manufactured by Daicel Chemical Industries), 80 g of tetrahydrofuran (hereinafter referred to as THF) and 0.68 g of triethylamine were charged into the reactor, and the temperature was adjusted to 60 ° C. Stir. 0.75 g of methacryloyloxyethylene isocyanate (trade name: Karenz MOI, manufactured by Showa Denko KK) was sequentially added thereto, and after the addition, a heating reaction was performed at 60 ° C. to obtain a modified cellulose resin 2.

(Production Example 3)
In the same manner as in Production Example 1, 2.5 g of cellulose acetate (trade name: L-20 manufactured by Daicel Chemical Industries) and 97 g of MEK were charged in a reactor, and the temperature was stirred at 50 ° C. To this, 2.5 g of methacryloyl isocyanate (trade name: MAI, manufactured by Nippon Paint Co., Ltd.) was dropped, and after the dropping, a heating reaction was performed at 60 ° C. to obtain a modified cellulose resin 3.

(Production Example 4)
In the same manner as in Production Example 1, 2.5 g of cellulose acetate (trade name: L-70 manufactured by Daicel Chemical Industries), 80 g of THF, and 0.03 g of dibriltin dilaurate were charged into the reactor, and the temperature was stirred at 50 ° C. 1.65 g of methacryloyloxyethylene isocyanate (trade name: Karenz MOI, manufactured by Showa Denko KK) was added dropwise thereto, and after the dropwise addition, a heating reaction was performed at 60 ° C. to obtain a modified cellulose resin 4.

<Example 1>
(Formation of heat-resistant slip layer)
Apply a coating solution for forming a heat-resistant slipping layer having the following composition on one side of a polyethylene terephthalate film (PET) having a thickness of 4.5 μm as a substrate by gravure coating so that the dry coating amount is 1.0 g / cm ^2. And dried to form a heat resistant slipping layer.

(Coating fluid for forming heat resistant slipping layer)
-13.6 parts of polyvinyl butyral resin (trade name S-REC BX-1 manufactured by Sekisui Chemical Co., Ltd.)
・ 0.6 parts of polyisocyanate curing agent (trade name Takenate D218, Takeda Pharmaceutical Company Limited)
・ Phosphate ester 0.8 parts (Brand name Price Surf A208S, Daiichi Kogyo Seiyaku Co., Ltd.)
・ Methyl ethyl ketone 42.5 parts ・ Toluene 42.5 parts

(Formation of dye transfer layer)
On the surface opposite to the surface on which the heat-resistant slip layer of the base material was formed, a composition for forming a dye transfer layer having the following composition was diluted with methyl ethyl ketone to adjust the solid content of the composition to 5%. The one heated in the step was applied with a bar (the coating amount was 0.6 g / m ² (when dried)). Next, it is dried in an oven at 80 ° C. for 5 minutes, and then UV-cured (UV irradiation device, manufactured by Fusion UV Systems Japan Co., Ltd., light source; H bulb, 500 mJ / cm ² ) to obtain the sublimation type thermal transfer sheet A of the present invention. It was.

(Dye transfer layer forming composition (Example 1))
-Modified cellulose resin 1 (based on solid content) 100 parts-Photopolymerization initiator 5 parts (trade name Irg. 184: manufactured by Ciba Specialty Chemicals)
-40 parts of photocurable monomer (trade name KAYARAD DPCA-20 manufactured by Nippon Kayaku Co., Ltd.)
・ Release agent: Acrylic modified silicone 4 parts
(Product name: FS-730, NOF Corporation)
・ Cyclohexanone 5 parts ・ C. I. Disperse Yellow-201 280 parts

<Example 2>
A sublimation type thermal transfer sheet B of the present invention was obtained in the same manner as in Example 1 except that the composition for forming a dye transfer layer having the following composition was used.

(Dye transfer layer forming composition (Example 2))
-Modified cellulose resin 2 (based on solid content) 100 parts-Photopolymerization initiator 5 parts (trade name Irg. 184, manufactured by Ciba Specialty Chemicals)
-30 parts of photocurable monomer (trade name KAYARAD DPCA-60 manufactured by Nippon Kayaku Co., Ltd.)
・ Parting agent (trade name: KF615, Shin-Etsu Chemical Co., Ltd.) 3 parts ・ Cyclohexanone 10 parts ・ C. I. Disperse Yellow-201 270 parts

<Example 3>
A sublimation type thermal transfer sheet C of the present invention was obtained in the same manner as in Example 1 except that the dye transfer layer forming composition having the following composition was used.

(Dye transfer layer forming composition (Example 3))
・ Modified cellulose resin 3 (based on solid content) 100 parts ・ Photopolymerization initiator 8 parts (trade name Irg. 184, manufactured by Ciba Specialty Chemicals)
・ 40 parts of photocurable monomer (trade name: KAYARAD HX-220, manufactured by Nippon Kayaku Co., Ltd.)
・ Parting agent 4 parts (Brand name KF615 Shin-Etsu Chemical Co., Ltd.)
・ C. I. Disperse Yellow-201 290 parts

<Example 4>
A sublimation thermal transfer sheet D of the present invention was obtained in the same manner as in Example 1 except that the composition for forming a dye transfer layer having the following composition was used.

(Dye transfer layer forming composition (Example 4))
-Modified cellulose resin 4 (based on solid content) 100 parts-Photopolymerization initiator 8 parts (trade name Irg. 184, manufactured by Ciba Specialty Chemicals)
-30 parts of photocurable monomer (trade name Ebecryl 2047 manufactured by Daicel UCB)
-Mold release agent: 1 part of alkyl-modified silicone (trade name: KF-412 manufactured by Shin-Etsu Chemical Co., Ltd.)
・ C. I. Disperse Yellow-201 250 parts

<Comparative example>
A heat resistant slipping layer was formed on the substrate by the same method as in Example 1. Next, after the composition for forming a dye transfer layer having the following composition is diluted with methyl ethyl ketone on the surface opposite to the surface on which the heat-resistant slip layer of the substrate is formed, the solid content of the composition is adjusted to 5%. What was heated at 40 ° C. was coated with a bar (coating amount was 0.6 g / m ² (when dried)). Furthermore, it was dried in an oven at 80 ° C. for 5 minutes to obtain a sublimation thermal transfer sheet E.

(Dye transfer layer forming composition (comparative example))
・ Cellulose acetate resin 100 parts (trade name L-20 manufactured by Daicel Chemical Industries)
・ Silicone: 5 parts of acrylic modified silicone (trade name: FS-730, manufactured by NOF Corporation)
・ Polycaprolactone 50 parts (Brand name PLACCEL H5 manufactured by Daicel Chemical Industries)
・ C. I. Disperse Yellow-201 210 parts

(Production of image receiving sheet)
A composition for forming a receiving layer having the following composition was diluted with methyl ethyl ketone / toluene (1/1) to adjust the solid content to 10%. Thereafter, the diluted composition for forming a receiving layer was coated on synthetic paper with a bar coater. Subsequently, it was dried in an oven at 120 ° C. for 5 minutes to produce an image receiving sheet having a receiving layer. The coating amount of the receiving layer was 4 g / m ² (when dried).

(Receptive layer forming composition)
・ 100 parts of polyvinyl butyral resin (trade name S-REC BM-1 manufactured by Sekisui Chemical Co., Ltd.)
-Release agent Silicone: 5 parts of acrylic modified silicone (trade name: FS-730, manufactured by NOF Corporation)

<Evaluation>
The dye transfer layer of the sublimation type thermal transfer sheet prepared in Examples 1 to 4 and the comparative example and the receiving layer of the image receiving sheet are stacked so as to face each other, and printing is performed from the back surface of the sublimation type thermal transfer sheet under the following conditions. And an image was formed. When any of the above sublimation type thermal transfer sheets was used, 2.0 ≦ OD, and a high-density printed product could be obtained. Table 1 shows the evaluation at this time. Each test was performed by the following method.

(Print evaluation)
Condition Printing voltage 32V
Printing speed 1msec / Line
Heating element average resistance 5285Ω
Print density in main scanning direction 300 dpi
Sub-scanning direction printing density 300 dpi

(Print density test)
An image was formed under the above conditions, and the value at which the optical reflection density (OD) was maximized was measured by an optical densitometer (Spectrolino manufactured by Gretag Macbeth).

(Releasability test)
When the image was printed, it was examined according to the following evaluation criteria whether there was any thermal fusion between the image receiving sheet and the sublimation type thermal transfer sheet, or whether there was any problem when peeling by hand.
○: There is almost no resistance when peeling, and there is no problem caused by thermal fusion between the thermal transfer image-receiving sheet and the thermal transfer sheet.
Δ: Resistance is felt when peeling.
×: Cannot be peeled off due to heat fusion (abnormal transfer).

(Ribbon storage stability test)
Two types of the sublimation type thermal transfer sheet were prepared, which were kept in a room and those stored for 96 hours in an environment of a temperature of 40 ° C. and a humidity of 90% RH, and the respective print densities were measured by the above method. The evaluation criteria are as follows.
○: (1- (OD before storage) / (OD after storage)) × 100 is 15 (%) or less.
X: (1- (OD before storage) / (OD after storage)) * 100 is 15 (%) or more.

(Ribbon blocking test)
The transfer surface and the back surface of the sublimation type heat transfer sheet are overlapped, and a load of 20 kg / cm ² is applied in an environment of 50 ° C. and humidity 80% RH, and after storage for 96 hours, the dye layer adheres to the back side. Whether or not the dye layer was removed due to this was visually judged according to the following evaluation criteria.
○: Dye layer is not removed.
Δ: Part of the dye layer is removed.
X: Dye layer is removed.

It is a schematic sectional drawing which shows an example of the sublimation type thermal transfer sheet of this invention. It is explanatory drawing explaining the sublimation type | mold thermal transfer sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Dye transfer layer 3 ... Sublimation type thermal transfer sheet

Claims (2)

A sublimation type thermal transfer sheet having a substrate and a dye transfer layer formed on the substrate and having dye transfer properties,
The dye transfer layer contains a sublimation dye, an ultraviolet curable resin, and a photopolymerization initiator,
A sublimation type thermal transfer sheet, wherein the ultraviolet curable resin is a photosensitive cellulose resin. The photosensitive cellulose resin, wherein the hydroxyl group of the cellulose or cellulose derivative, a modified cellulose resin obtained by reacting an isocyanate group of the compound represented by the following formula (1), according to claim 1 The sublimation type thermal transfer sheet described in 1.

In the above formula, R ¹ represents —H or —CH ₃ ; R ² represents an alkylene group having 1 to 5 carbon atoms which may have an alkyl group in the side chain.

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