JP5043737B2 - Thermal transfer sheet and thermal transfer recording material - Google Patents

Description

  The present invention comprises a thermal transfer sheet, the thermal transfer sheet, and a thermal transfer image-receiving sheet provided with a dye-receiving layer on at least one surface of a substrate, and the dye layer of the thermal transfer sheet and the dye-receiving layer of the thermal transfer image-receiving sheet. The present invention relates to a thermal transfer recording material capable of transferring the dye in the dye layer to the dye receiving layer by superimposing and heating means, and in particular, corresponding to the increase in printing speed, the dye layer of the thermal transfer sheet and the transfer target (thermal transfer) in printing. A thermal transfer sheet that prevents abnormal transfer and thermal fusion with the image receiving sheet), has good adhesion and storage stability with the base material sheet, has excellent print density, and prevents uneven color of the print, and The present invention relates to the thermal transfer recording material used.

Conventionally, various thermal transfer recording methods are known. Among them, a thermal transfer sheet having a dye layer in which a dye for sublimation transfer is used as a recording material and this is supported on a base material such as a polyester film with a suitable binder. From the above, there are proposed methods for forming various full-color images by thermally transferring a sublimation dye onto a transfer material that can be dyed with a sublimation dye, for example, a thermal transfer image-receiving sheet having a dye-receiving layer formed on paper or a plastic film. Yes. In this case, as a heating means, yellow, magenta, cyan, and if necessary, color dots in which a large number of heating amounts of three colors or four colors of black are adjusted by heating with a thermal head of the printer are used as a thermal transfer image receiving sheet. The full color of the original is reproduced by the multicolored dots. The image formed in this way is very clear and excellent in transparency because the coloring material used is a dye, so the resulting image is excellent in the reproducibility and gradation of intermediate colors, It is possible to form a high-quality image similar to an image obtained by offset printing or gravure printing and comparable to a full-color photographic image. Therefore, the sublimation transfer method is used as information recording means in various fields.

  With the development of various hardware and software related to multimedia, this thermal transfer recording method is a full color hard copy of analog images such as digital graphics and video represented by computer graphics, satellite communication still images and CD-ROM etc. As a system, its market is expanding. The specific uses of the image receiving sheet by this thermal transfer method are diverse. Typical examples include printing proofs, image output, CAD / CAM design and design output, various medical analytical instruments such as CT scans and endoscope cameras, measuring instrument output applications, and instant photography. As an alternative to the above, for output of ID cards, ID cards, credit cards, and other facial images of cards, etc., as well as composite photos and amusement photos at amusement facilities such as amusement parks, game centers, museums, and aquariums Can be mentioned.

  In the dye layer of the thermal transfer sheet used in the sublimation type thermal recording system, the binder has many required functions such as compatibility with the heat sublimation dye and running property in the printer. Therefore, the materials that can be used as the binder of the dye layer are limited. For example, in Patent Document 1, a polyvinyl acetal resin is used. Moreover, in patent document 2, it consists of a mixture of polyvinyl butyral and a cellulose polymer from the point of the storage stability of the dye in a binder as a binder of a dye layer, and a cellulose polymer is 65 to 85 weight% of polyvinyl butyral. Disclosed is a binder that is 15-35% by weight. However, in conventional thermal transfer sheets such as those disclosed in these patent documents, the thermal transfer sheet and the image receiving sheet are fused to each other by heating during recording, and a part of the dye layer after printing is transferred to the receiving layer side. There has been a problem that abnormal transfer occurs or the dye layer and the receiving layer are not peeled off after printing.

  Recently, the problem of thermal fusion between the dye layer of the thermal transfer sheet and the receiving layer of the thermal transfer image-receiving sheet has been increasing because of the increase in the speed of printers and the use of various image-receiving sheets as described above. This is the main background. That is, in recent years, as the printing speed of thermal transfer printers has increased, there has been a problem that sufficient print density cannot be obtained. Even if the speed of the printer is increased, the voltage applied to the thermal head per unit time is increasing in order to obtain a sufficient print density. As a result, the energy applied to the thermal transfer sheet per unit time is increased, and thermal fusion of the dye layer is likely to occur. Therefore, it is difficult to use a high-speed printer with the polyvinyl acetal resin as disclosed in the related art, and there is a demand for a thermal transfer sheet with improved release performance that can be peeled off even when high energy is applied.

  On the other hand, as the specific application of the image receiving sheet by the thermal transfer method has been diversified, there has been a demand to use a receiving layer made of a material different from the receiving layer conventionally used for the image receiving sheet. For example, in various card applications, polyvinyl chloride (PVC) has been mainly used as a receiving layer in the past. However, in consideration of the environment, it has been changed to a material that does not generate harmful gases such as chlorine and hydrogen chloride during incineration. An alternative is sought. As such an alternative material, for example, when a polyester such as polylactic acid or an amorphous polyethylene terephthalate copolymer is used, the dye layer does not cause heat fusion when the receiving layer is polyvinyl chloride. However, it will cause intense heat fusion. Therefore, there is a demand for a thermal transfer sheet that can be printed even on a receiving layer that is likely to cause thermal fusion and has good releasability.

  In order to prevent thermal fusion from occurring, there is a method of adding a silicone-based release agent to the dye layer or the receiving layer (for example, Patent Document 3). However, when a release agent is added in a large amount to the dye layer, the storage stability of the thermal transfer sheet is often deteriorated, for example, the dye is transferred to the back layer. Furthermore, when a large amount of a release agent is added to the dye layer, the adhesion between the substrate and the dye layer is reduced, or when the dye layer is formed on the substrate, the dye layer ink is repelled on the substrate. However, there is a problem that uniform layer formation becomes difficult and color unevenness occurs in an image. Therefore, if a release agent is put in a large amount in the receiving layer, the release agent inhibits dyeing and the printing sensitivity is lowered and the printing density is lowered. There is a problem that the whiteness of the image is reduced, or the image is smeared or soiled.

On the other hand, Patent Document 4 provides a thermal transfer recording material that is capable of high-speed printing, has excellent printing density even during high-speed printing, and can obtain a thermal transfer printed material having high durability such as light resistance. For this purpose, it is disclosed that the binder resin contained in the dye layer contains a cellulosic resin. However, when 50% or more of the binder resin contained in the dye layer is a cellulose resin as in Patent Document 4, there may be a problem in the adhesion and storage stability between the substrate and the dye layer. .
Japanese Patent Laid-Open No. 60-101087 JP-A-3-19894 JP-A-1-200990 JP 2007-090780 A

  Accordingly, the present invention has been made in view of such a situation, and prevents abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, while corresponding to the increase in printing speed. Furthermore, an object is to provide a thermal transfer sheet that has good adhesion and storage stability with a base sheet, excellent printing density, and prevents uneven color printing, and a thermal transfer recording material using the thermal transfer sheet. .

  The thermal transfer sheet of the present invention is the thermal transfer sheet according to claim 1, wherein a heat-resistant slipping layer is provided on one side of the base sheet, and a dye layer containing a dye and a binder is provided on the other side of the base sheet. In the sheet, the binder in the dye layer contains a polyvinyl acetoacetal resin, a polyvinyl butyral resin, and a cellulose resin.

  This prevents abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, while maintaining high printing speed, and also provides adhesion and storage stability with the base sheet. It is possible to obtain a dye layer that is excellent in printing density and prevents color unevenness in printing.

  According to claim 2, in the total solid content of the binder in the dye layer, the polyvinyl acetoacetal resin is contained in an amount of 60 to 80% by weight, the polyvinyl butyral resin is contained in an amount of 20 to 30% by weight, and the cellulose resin is contained in an amount of 1 to 10% by weight. It is characterized by that. As a result, abnormal transfer and heat fusion corresponding to an increase in printing speed can be further prevented, the print density is higher, and uneven color printing can be further prevented.

  According to a third aspect of the present invention, the cellulosic resin is ethyl cellulose. Thereby, even if a high energy is applied at the time of printing or a receiving layer which is easily fused, the release performance is improved so that it can be peeled, and it is preferable from the viewpoint of the storage stability of the thermal transfer sheet.

  According to a fourth aspect of the present invention, the release agent is contained in the dye layer in an amount of 3 parts by weight or less based on 100 parts by weight of the total solid content of the dye layer binder. Thereby, abnormal transfer and thermal fusion with the transfer medium can be further prevented, and the release performance is improved, which is preferable.

  The thermal transfer recording material of the present invention comprises, as claimed in claim 5, a thermal transfer sheet according to any of the above and a thermal transfer image-receiving sheet provided with a dye-receiving layer on at least one surface of a substrate, and the dye of the thermal transfer sheet Layer and the dye-receiving layer of the thermal transfer image-receiving sheet, in a thermal transfer recording material capable of transferring the dye in the dye layer to the dye-receiving layer by heating means, the dye-receiving layer of the thermal transfer image-receiving sheet is polyester, polyurethane, And at least one selected from the group consisting of polycarbonate as a main component.

  The thermal transfer sheet of the present invention is capable of preventing abnormal transfer or thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, while responding to an increase in printing speed, and the adhesion between the base sheet and the dye layer. Properties and storage stability are excellent, the print density is excellent, and uneven color of the print is prevented. In addition, the thermal transfer recording material of the present invention prevents abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, while corresponding to the increase in printing speed, and the base sheet and dye. The adhesiveness and storage stability of the layers are good, the printing density is excellent, and the color unevenness of the printing is prevented.

  FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermal transfer sheet of the present invention, in which a thermal head on one surface of a substrate sheet 1 improves the slidability of the thermal head and prevents sticking. 3 and the dye layer 2 is formed on the other surface of the base sheet 1. FIG. 2 is a schematic cross-sectional view showing another embodiment of the thermal transfer sheet of the present invention. The heat-resistant slip layer 3 is provided on one surface of the base sheet 1 and the other surface of the base sheet 1 is provided. The undercoat layer 4 and the dye layer 2 are sequentially formed in order to improve the adhesion between the base sheet and the dye layer and to improve the thermal transfer characteristics.

  In the thermal transfer sheet of the present invention, at least a dye layer is provided on the other side of the base sheet provided with a heat-resistant slipping layer on one side. The dye layer provided on the other surface of the base sheet may be composed of a single layer of one color, for example, a plurality of dyes having different hues such as yellow, magenta, and cyan dye layers. The layers may be repeatedly formed on the same surface of the same base material in the surface order. Further, the thermal transfer sheet of the present invention may have a mode in which a thermal transferable protective layer that gives a function of protecting the transferred dye is repeatedly formed on the same surface of the same substrate as the dye layer in the surface order. .

Hereinafter, each layer constituting the thermal transfer sheet of the present invention will be described in detail.
(Base material sheet)
The base sheet 1 of the thermal transfer sheet used in the present invention may be any material as long as it has a conventionally known degree of heat resistance and strength, for example, about 0.5 to 50 μm, preferably about 1 to 10 μm. Polyethylene terephthalate film of thickness, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, Examples thereof include cellulose derivatives such as cellulose acetate, polyethylene films, polyvinyl chloride films, nylon films, polyimide films, ionomer films, and the like.

  The plastic film of the base material sheet is formed on the dye layer or the undercoat layer described later in order to improve the adhesion between the base material and the dye layer or the undercoat layer. It is preferable to perform an adhesion treatment on the surface on which the undercoat layer is formed. As the adhesion treatment, known resin surface modification 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. Quality technology can be applied as it is. Two or more of these treatments can be used in combination. The primer treatment can be performed, for example, by applying a primer solution to an unstretched film at the time of film formation by melt extrusion of a plastic film and then stretching the film. Among the bonding treatments, corona discharge treatment or plasma treatment that can be easily obtained without increasing the cost is preferable.

(Dye layer)
The dye layer 2 of the present invention is a layer formed by supporting a heat transfer dye with a specific binder described later. The dye to be used is a dye that melts, diffuses, or sublimates and transfers by heat. Any of the dyes used in conventionally known sublimation transfer type thermal transfer sheets can be used in the present invention, but is appropriately selected in consideration of hue, printing sensitivity, light resistance, storage stability, solubility in binder, etc. To do.

  Examples of the dye include azomethines such as diarylmethane, triarylmethane, thiazole, merocyanine, pyrazolone methine and the like, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazolazomethine, imidazoazomethine, and pyridone azomethine. , Xanthene, oxazine, dicyanostyrene, cyanomethylene represented by tricyanostyrene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrrolazo, pyralazo, imidazoleazo, Azos such as thiadiazole azo, triazole azo, dizazo, spiropyran, indolinospiropyran, fluoran, rhodamine lactam, naphthoquinone, anne Rakinon system include the quinophthalone like.

  In the present invention, the binder of the dye layer contains a polyvinyl acetoacetal resin, a polyvinyl butyral resin, and a cellulose resin, and includes the polyvinyl acetoacetal resin as a main component of the dye layer binder, and the polyvinyl butyral resin. And cellulosic resin. Containing the polyvinyl acetoacetal resin as a main component of the dye layer binder means that the most contained component in the binder is the polyvinyl acetoacetal resin, and the polyvinyl acetoacetal resin is based on the entire dye layer binder. In this sense, it is included in excess of 50% by weight. As long as the effects of the present invention are not impaired, other binder resins may be added in addition to the specific polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin.

  The content of the polyvinyl acetoacetal resin is preferably 60 to 80% by weight of the total solid content of the binder in the dye layer, more preferably from the viewpoint of storage stability of the thermal transfer sheet, releasability from the image receiving sheet, and the like. Is 60 to 70% by weight of the total binder. If the content of the polyvinyl acetoacetal resin is too small, problems such as poor adhesion to the substrate sheet and poor storage stability of the thermal transfer sheet arise. On the other hand, when the content of the polyvinyl acetoacetal resin is too large, there are problems such as a decrease in transfer sensitivity and a decrease in printing density.

  Moreover, it is preferable to contain 20-30 weight% of polyvinyl butyral resin and 1-10 weight% of cellulosic resins in the total solid of a dye layer binder. If the content of the polyvinyl butyral resin is too small, problems such as poor adhesion to the substrate sheet and poor storage stability of the thermal transfer sheet arise. On the other hand, when the content of the polyvinyl butyral resin is too large, problems such as abnormal transfer occur and the storage stability of the thermal transfer sheet decreases.

  If the content of the cellulose resin in the dye layer is too small, problems such as abnormal transfer occur. On the other hand, when the content of the cellulose-based resin is too large, problems such as a decrease in adhesion to the base sheet and a decrease in storage stability of the thermal transfer sheet arise. The thermal transfer sheet of the present invention comprises, as a dye layer binder, a polyvinyl acetoacetal resin as a main component, a polyvinyl butyral resin, and a cellulose resin, and a dye layer composed of these three component resins. While responding to higher printing speeds, abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target during printing are prevented, and adhesion to the base sheet and storage stability are good. It has excellent density and can prevent uneven color printing.

  The composition of the above dye layer is that the three components of the dye layer binder, polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulosic resin, have low compatibility with each other, they are separated, It is considered that the structure can be easily formed and the functions of each of the three components can be exhibited, and as a result, the releasability from the thermal transfer sheet is easily improved while maintaining the storage stability of the thermal transfer sheet.

  The polyvinyl acetal resin is obtained by reacting polyvinyl alcohol with an aldehyde to acetalize, but the polyvinyl acetoacetal resin used in the dye layer of the present invention is mainly composed of acetaldehyde as the aldehyde, It has become. Moreover, the polyvinyl butyral resin used for the dye layer of the present invention is acetalized using mainly butyraldehyde as the aldehyde.

  In the case of polyvinyl acetoacetal resin, in the acetalized structural unit, the ratio of acetoacetal groups is high, and the ratio of acetoacetalization degree to acetoacetalization degree (acetoacetalization / total acetalization), that is, acetalization is achieved. The ratio of the number of moles of the structural unit in which acetaldehyde is used to acetoacetalize is 50% to 100% with respect to the total number of moles of the structural unit. In the present invention, the degree of acetoacetalization is preferably close to 100%, and the degree of acetoacetalization of 100% is the most excellent in releasability from a thermal transfer sheet and storage stability, and the transfer sensitivity in printing. Is also preferable.

  In the case of polyvinyl butyral resin, the proportion of butyral groups is high in the acetalized structural unit, and the ratio of the butyral degree to the total acetalization degree (butyralization / total acetalization), that is, the acetalized structural unit The ratio of the number of moles of the structural unit butyralized using butyraldehyde is from 50% to 100% with respect to the total number of moles. In the present invention, the degree of butyralization is preferably 60% to 100%, the releasability from the thermal transfer sheet and the storage stability are good, and the transfer sensitivity in printing is high.

  Further, the cellulose-based resin of the dye layer binder used in the present invention is a resin made of a cellulose derivative, and a resin in which an arbitrary functional group is bonded to part or all of the hydroxyl groups of cellulose is mainly used. The functional group to be bonded to the hydroxyl group of cellulose may be appropriately selected according to various physical properties that are important for the dye layer while obtaining the effects of the present invention. In the present invention, two or more types of cellulose resins having different bonded functional groups may be mixed and used. Examples of the cellulose resin used in the present invention include methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, acetyl cellulose, and acetyl cellulose butyrate. Of these, ethylcellulose is preferred because it is excellent in improving the release performance so that it can be peeled off even when it is subjected to high energy or is easily fused.

  Ethylcellulose is a cellulose ether made by reacting ethyl chloride with alkali cellulose, and has a hydroxyl group substituted with an ethoxyl group. Among these, ethylcellulose having an ethoxyl group content of 44 to 50% is preferable from the viewpoint of strength and flexibility. In ethyl cellulose, the ethoxyl group content is preferably 46 to 49.5%, more preferably 48 to 49.5%, from the viewpoint of storage stability of the thermal transfer sheet. Here, the ethoxyl group content is a molecular weight of a substituted ethoxyl group with respect to a molecular weight per unit structure, and is obtained by ethoxyl group content = (molecular weight of substituted ethoxyl group) / (molecular weight per unit structure). Can do. In the case of complete substitution, (molecular weight of three ethoxyl groups) / (molecular weight per unit structure) = 135/246 = 54.88%.

  In the present invention, the cellulose-based resin used as the binder of the dye layer is contained in the total solid content of the binder in an amount of 1 to 10% by weight. Among them, the inclusion of 3 to 10% by weight improves the abnormal transfer prevention performance. From the viewpoint of improving storage stability. As a binder of the dye layer, other binder resins may be mixed with the above-mentioned specific polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin as long as the effects of the present invention are not impaired. Examples of such other binder resins include polyvinyl acetal resins that do not correspond to the specific resin, vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, and phenoxy resins. Can be mentioned.

  The dye layer of the thermal transfer sheet used in the present invention may contain a compound other than the binder resin and the heat transfer dye as necessary. Examples of other compounds used in the present invention include mold release agents. In the present invention, the binder itself used in the dye layer of the thermal transfer sheet provides an effect that it is difficult to fuse with the receptor layer of the thermal transfer image-receiving sheet. Can be improved. However, if a lot of release agent is added, when the adhesion between the base sheet and the dye layer is reduced or the dye layer is formed on the base sheet, the dye layer ink is repelled on the base sheet, Since it may be difficult to form a uniform layer and color unevenness may occur in the image, use a small amount within the range where such a problem does not occur and the effect of preventing thermal fusion is improved. Is preferred. A mold release agent is used 1 type or in mixture of 2 or more types. The amount of release agent added is 3% by weight with respect to 100 parts by weight of the total solid content of the binder from the viewpoints of adhesion to the base sheet, uniform layer formation, and prevention of hue change of the dye layer described later. Part or less.

  The release agent can be appropriately selected and used depending on the dye to be combined. Examples of the mold release agent include phosphate esters, silicone surfactants, fluorine surfactants, and the like. As the mold release agent used in the present invention, a phosphoric ester is preferable because it has an effect of improving the mold releasability even in a small amount, but does not adversely affect the surface shape of the dye layer. However, since the phosphate ester may decolorize the dye, the dye to be combined and the phosphate ester are appropriately selected and used. As the phosphate ester, an acid type and / or a neutralized phosphate ester is preferably used.

  It is preferable to mix acid-type and neutral-type phosphate esters and use them in the dye layer from the viewpoint of preventing hue changes in the dye layer. The mixing ratio of the acid type and neutralization type of the phosphate ester is such that the acid type / neutralization type = 80/20 to 50/50 can suppress the reaction between the dye and the phosphate ester. This is preferable from the viewpoint of preventing hue change. In particular, in the case where the concentration is improved by using indaniline and methine dyes in combination, it is effective to apply the above phosphate ester.

  Further, a silane coupling agent can be added to the dye layer. Examples of silane coupling agents include those containing isocyanate groups such as γ-isocyanatopropyltriethoxysilane and γ-isocyanatopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β -(Aminoethyl) -γ-aminopropyltriethoxysilane, those containing amino groups such as γ-phenylaminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane and β- (3,4-epoxy And those containing an epoxy group such as (cyclohexyl) ethyltrimethoxysilane. These can be used alone or as a mixture of two or more.

  In the silane coupling agent, for example, a silanol group generated by hydrolysis is condensed with a hydroxyl group of an inorganic oxide on the surface of the thin film layer to be chemically bonded to improve the adhesion. In addition, the epoxy group, amino group, etc. of the silane coupling agent react with the hydroxyl group, carboxyl group, etc. of the resin binder to chemically bond, improve the strength of the dye layer itself, cohesive failure of the dye layer during thermal transfer, etc. Can be prevented.

  In the dye layer of the present invention, the total amount of dyes is realized from the viewpoint of realizing a thermal transfer sheet excellent in color development properties while preventing the dye from transferring to the heat-resistant slipping layer on the back side of the thermal transfer sheet during winding and storage. The weight ratio (D / B) between (D) and the total amount (B) of the dye layer binder is preferably 2 to 2.5, more preferably 2.3 to 2.4.

The dye layer may contain the above-mentioned dyes, binders, and other various additives similar to those conventionally known in addition to the above-mentioned release agent and silane coupling agent, if necessary. Examples of the additive include organic fine particles such as polyethylene wax and inorganic fine particles in order to improve releasability from the image receiving sheet and ink coating suitability. Such a dye layer is usually prepared by adding the above-mentioned dye, binder, and additives as necessary in an appropriate solvent, and dissolving or dispersing each component to prepare a coating solution. The liquid can be formed on a substrate sheet by applying and drying. 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 layer thus formed has a coating amount at the time of drying of about 0.2 to 6.0 g / m ² , preferably about 0.3 to 3.0 g / m ² .

(Heat resistant slipping layer)
In the thermal transfer sheet of the present invention, a heat resistant slipping layer 3 is provided on one surface of the substrate sheet in order to prevent adverse effects such as sticking and printing wrinkles due to the heat of the thermal head. The resin for forming the heat-resistant slipping layer may be any 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 resin, cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, aromatic polyamide resin, polyimide resin, polyamideimide resin, poly 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, metal soap, silicone oil, graphite powder, silicone graft polymer, fluorine graft polymer, acrylic silicone graft polymer, acrylic. Examples thereof include silicone polymers such as siloxane and arylsiloxane. Preferably, it is a layer made of a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound, and a phosphate ester compound, and a filler may be added. More preferred.

The heat-resistant slipping layer is prepared by dissolving or dispersing the above-described resin, slipperiness-imparting agent, and filler in an appropriate solvent on the base sheet to prepare a heat-resistant slipping layer coating solution. This 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, 0.1g / m 2 ~3.0g / m} 2 is preferred.

(Underlayer)
In the thermal transfer sheet of the present invention, an undercoat layer 4 is provided between the base sheet and the dye layer for the purpose of improving the adhesion between the base sheet and the dye layer or improving the thermal transfer characteristics. May be. As the resin constituting the undercoat layer formed with the thermal transfer sheet of the present invention, preferred are polyester resins, acrylic resins, urethane resins, alkyd resins, homopolymers of N-vinyl pyrrolidone, or N-vinyl pyrrolidone. And copolymers with other components. In order to improve adhesion to the base sheet or dye layer, protective layer, or environmental preservation, the undercoat layer has a melamine compound, an isocyanate compound, an epoxy compound, a compound containing an oxazoline group, a chelate It is preferable to add a compound or the like.

  Examples of the N-vinylpyrrolidone include N-vinyl-2-pyrrolidone, N-vinyl-3-pyrrolidone, and N-vinyl-4-pyrrolidone. A homopolymer of this vinylpyrrolidone (a homopolymer of the same monomer species). ), Or a copolymer of these different monomers. Such a polyvinyl pyrrolidone resin has an official K value of Fickencher, and a grade of K-60 to K-120 can be used, and a number average molecular weight is about 30,000 to 280,000. By using this polyvinyl pyrrolidone resin for the undercoat layer, the transfer sensitivity is increased, and transfer unevenness and foil breakage failure of the protective layer transfer are prevented. When the polyvinyl pyrrolidone resin having a K value of less than 60 (K-15, K-30) is used, the effect of improving the transfer sensitivity in printing may not be exhibited.

  Also, a copolymer of the above-described N-vinylpyrrolidone and other copolymerizable monomer can be used. Examples of the copolymerizable monomer other than N-vinylpyrrolidone include vinyl such as styrene, vinyl acetate, acrylate ester, acrylonitrile, maleic anhydride, vinyl chloride (fluorinated) vinyl, and chloride (fluorinated and cyanated) vinylidene. Monomer. A copolymer obtained by radical copolymerization of the vinyl monomer and N-vinylpyrrolidone can be used. In addition, block copolymers, graft copolymers, and the like of polyester resins, polycarbonate resins, polyurethane resins, epoxy resins, acetal resins, butyral resins, formal resins, phenoxy resins, cellulose resins and the like and polyvinylpyrrolidone can also be used.

  Moreover, in the undercoat layer, a resin can be mixed in addition to the polyvinylpyrrolidone resin to improve the adhesiveness. Examples of the resin include polymers (copolymers) obtained from vinyl monomers such as styrene, vinyl acetate, acrylic acid esters, acrylonitrile, maleic anhydride, vinyl chloride (fluorinated) vinyl chloride (fluorinated, cyanated) vinylidene, and polyester resins. Polycarbonate resin, polyurethane resin, epoxy resin, acetal resin, butyral resin, formal resin, phenoxy resin, cellulose resin, polyvinyl alcohol resin and the like. Such a resin component is preferably added and used at a ratio of 1 to 30% by weight with respect to the solid content of the entire undercoat layer. If the addition amount of the resin component is small, sufficient adhesiveness cannot be exhibited. If the addition amount of the resin component is too large, the effect of improving the transfer sensitivity of polyvinyl pyrrolidone cannot be exhibited sufficiently.

  In addition, the undercoat layer in the thermal transfer sheet of the present invention prevents dye migration from the dye layer to the undercoat layer during printing, and effectively performs dye diffusion to the receiving layer side of the image receiving sheet, thereby enabling printing in printing. An undercoating layer made of colloidal inorganic pigment ultrafine particles may be used from the viewpoint of high transfer sensitivity and high printing density. Conventionally known compounds can be used as the colloidal inorganic pigment ultrafine particles. For example, silica (colloidal silica), alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or its hydrate, suspect boehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, magnesium oxide, oxidation Examples include titanium. In particular, colloidal silica and alumina sol are preferably used. These colloidal inorganic pigment ultrafine particles have a primary average particle size of 100 nm or less, preferably 50 nm or less, particularly preferably 3 to 30 nm, and thereby sufficiently exhibit the function of the undercoat layer. it can.

  In addition, the shape of the colloidal inorganic pigment ultrafine particles may be any shape such as a spherical shape, a needle shape, a plate shape, a feather shape, or an amorphous shape. In addition, it is possible to use an acid type treated so as to be easily dispersed in a sol form in an aqueous solvent, a fine particle charge converted to a cation, or a fine particle surface treated. In consideration of coating suitability when the undercoat layer is applied, it is preferable that the coating liquid for the undercoat layer has a low viscosity and fluidity. Further, the undercoat layer may be an undercoat layer containing the resin and the colloidal inorganic pigment ultrafine particles.

In order to form the undercoat layer, a composition obtained by dissolving the above-mentioned material in a solvent such as acetone, methyl ethyl ketone, toluene, xylene, alcohol, or water selected according to the coating suitability or in a sol form is dispersed. After forming the coating liquid which becomes and apply | coating to the base-material surface using conventional coating means, such as a gravure coater, a die coater, a roll coater, and a wire, it can form by drying and solidifying. In the dry coating amount, 0.01~5g / m ^2, preferably from 0.05 to 1 g / m ^2.

  The thermal transferable protective layer that imparts the function of protecting the dye transferred to the image receiving sheet, which may be formed on the thermal transfer sheet of the present invention, is not particularly limited, and can be formed by a conventionally known method. In addition, the thermal transfer sheet of the present invention may be further provided with detection marks and other configurations provided on the thermal transfer sheet.

Next, the thermal transfer recording material according to the present invention will be described in detail.
The thermal transfer recording material according to the present invention comprises the thermal transfer sheet according to the present invention and a thermal transfer image-receiving sheet provided with a dye-receiving layer on at least one surface of a substrate, and the dye layer of the thermal transfer sheet and the thermal transfer image-receiving sheet The thermal transfer recording material is capable of transferring the dye in the dye layer to the dye receiving layer by heating means. The dye receiving layer of the thermal transfer image receiving sheet preferably contains one or more selected from the group consisting of polyester, polyurethane, and polycarbonate as a main component.

  One embodiment of the thermal transfer recording material of the present invention is shown in FIG. The illustrated thermal transfer recording material 30 is a combination of a thermal transfer sheet 10 and a thermal transfer image receiving sheet 20, and the thermal transfer sheet 10 is provided with a dye layer 2 on one side of the base sheet 1, and the other side of the base sheet 1. Is provided with a heat resistant slipping layer 3. The thermal transfer image receiving sheet 20 has a configuration in which the dye receiving layer 12 is provided on one surface of the substrate 11. The thermal transfer sheet according to the present invention is not limited to the one shown in the drawing, and an easy-adhesion layer or the like is provided between the base sheet and the dye layer, or a layer such as an antistatic layer on the heat-resistant slipping layer. May be formed. In the thermal transfer image receiving sheet of the present invention, at least one surface of the substrate 11 may also serve as the dye receiving layer 12. That is, at least one surface of the substrate has dye-dyeing properties, and the surface of the substrate itself is a dye-receiving layer.

  The thermal transfer recording material of the present invention is a case where the dye transfer layer of the thermal transfer image-receiving sheet contains as a main component a material that is easily heat-sealed due to various demands by using the thermal transfer sheet according to the present invention as a thermal transfer sheet. However, it is possible to prevent abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, while maintaining high printing speed, and it has good storage stability and can prevent uneven printing. .

The thermal transfer recording material of the present invention comprises a thermal transfer sheet and a thermal transfer image receiving sheet as a set, and the thermal transfer sheet used for the thermal transfer recording material of the present invention is the thermal transfer sheet according to the present invention. Yes, as described above.
Below, each layer of the component in the thermal transfer image-receiving sheet used in the thermal transfer recording material of the present invention will be described.

(Base material)
It is desirable that the base material 11 of the thermal transfer image-receiving sheet 20 has a role of holding the receiving layer and has mechanical characteristics that can withstand heat applied during image formation and that does not hinder handling. The material of such a substrate is not particularly limited. For example, polyester, polyarylate, polycarbonate, polyurethane, polyimide, polyetherimide, cellulose derivative, polyethylene, ethylene / vinyl acetate copolymer, polypropylene, polystyrene, acrylic, poly Vinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene / perfluoroalkyl vinyl ether, polyvinyl fluoride, tetrafluoroethylene / ethylene, tetrafluoroethylene / Various plastic films or sheets such as hexafluoropropylene, polychlorotrifluoroethylene, and polyvinylidene fluoride Can be used is not particularly limited.

  White films formed by adding white pigments and fillers to the above plastic films or sheets, or sheets having microvoids inside the substrate, as well as condenser paper, glassine paper, sulfuric acid paper, synthetic paper ( Polyolefin, polystyrene), fine paper, art paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, cellulose fiber paper, and the like. Moreover, the laminated body by arbitrary combinations of said base material can also be used. Typical examples include a laminate of cellulose fiber paper and synthetic paper, and cellulose fiber paper and a plastic film.

  Moreover, the base material which carried out the easy adhesion process on the surface and / or the back surface of said base material can also be used. The thickness of these base materials is usually about 3 to 300 μm, and it is preferable to use a base material of 100 to 250 μm in consideration of mechanical suitability and the like. Moreover, when the adhesiveness of a base material and the layer provided on it is scarce, it is preferable to perform an easily bonding process or a corona discharge process on the surface. When polyvinyl chloride, polyester, polypropylene resin, vinyl chloride / vinyl acetate copolymer or the like is used as the base material of the thermal transfer image-receiving sheet, the base material itself can serve as a receiving layer for the sublimation transfer dye. it can. Accordingly, when polyester or vinyl chloride / vinyl acetate copolymer is used as the base material of the thermal transfer image-receiving sheet in the present invention, the base material itself also serves as the dye-receiving layer of the present invention. There is no need to provide a separate receiving layer.

(Dye-receiving layer)
The dye-receiving layer 12 of the thermal transfer image-receiving sheet 20 in the present invention is provided on at least one surface of the substrate, receives the sublimation dye transferred from the thermal transfer sheet 10, and forms the formed thermal transfer image. It is for maintaining. As described above, when the base material also serves as the dye-receiving layer, it is not provided separately. However, when the base material does not serve as the dye-receiving layer, one or more types of thermoplastics are provided on at least one surface of the base material. Provided with resin.

  In the present invention, as the thermal transfer sheet, the thermal transfer sheet according to the present invention including a dye layer that is difficult to be thermally fused is used. Therefore, as the dye receiving layer, a crystalline polyethylene terephthalate copolymer, polyester such as polylactic acid; Polyurethane; Contains polycarbonate (polycarbonate) produced by reacting phosgene or carbonate with divalent phenol such as 2,2-bis (4-hydroxyphenyl) propane (abbreviated bisphenol A) or glycol. It becomes possible to do. “Containing as a main component” as used herein means that the main component contained in the dye-receiving layer is at least one selected from the group consisting of the above polyester, polyurethane, and polycarbonate, This means that at least one selected from the group consisting of polyurethane and polycarbonate is contained in an amount exceeding 50% by weight of the dye-receiving layer. Unless the effects of the present invention are impaired, other binder resins may be added in addition to the specific resin.

  Specific examples of the crystalline polyethylene terephthalate copolymer include a copolymer of terephthalic acid, ethylene glycol, and cyclohexanedimethanol. The polylactic acid may be a homopolymer such as poly (L-lactic acid), poly (DL-lactic acid), syndiotactic poly (DL-lactic acid), atactic poly (DL-lactic acid), or a copolymer. There may be. Examples of the polylactic acid copolymer include polylactic acid as described above, β-propiolactone, β-butyrolactone, ε-caprolactone, 11-undecanolide, 12-undecanolide and other medium to large ring lactones, trimethylene carbonate (TMC) and cyclic carbonate monomers such as methyl-substituted trimethylene carbonate and oligomers thereof, cyclic ester oligomers, hydroxy acids such as ricinoleic acid and esters thereof, linear carbonate oligomers, linear ester oligomers, ester-carbonate oligomers, Examples thereof include those obtained by copolymerizing a comonomer that forms a bond that can be copolymerized with lactide and can be subjected to the action of a hydrolase, such as an ether-ester oligomer.

  In addition, the binder resin for the dye receiving layer is supplementarily a halogenated polymer such as polyvinyl chloride or polyvinylidene chloride, polyvinyl acetate, ethylene vinyl acetate copolymer, vinyl chloride / vinyl acetate copolymer, polyacrylic ester. Further, vinyl resins such as polystyrene and polystyrene acrylic, acetal resins such as polyvinyl formal, polyvinyl butyral, and polyvinyl acetal, cellulose resins such as cellulose acetate, polyolefin resins, and the like may be additionally used.

  In the dye receiving layer, a release agent may be added to the binder resin. However, there is a problem that the release agent inhibits dyeing and the printing sensitivity is lowered and the printing density is lowered, or the release agent is discolored to reduce the whiteness of the receiving sheet, or the image It should be used within the qualitative and quantitative range so as not to cause the problem of blurring or soiling. As the release agent used in the receiving layer in the present invention, conventionally known release agents, for example, solid waxes such as polyethylene wax, amide wax, Teflon (registered trademark) powder, fluorine-based, phosphate ester-based surface activity Any agent, silicone, etc. can be used. A particularly preferable release agent is a modified silicone, specifically, 1) modified silicone oil side chain type, 2) modified silicone oil both end type, 3) modified silicone oil one end type, and 4) modified silicone oil side chain. Both terminal types, 5) silicone graft acrylic resin, 6) methylphenyl silicone oil, etc. are mentioned.

  Modified silicone oils are divided into reactive silicone oils and non-reactive silicone oils. Examples of the reactive silicone oil include amino modification, epoxy modification, carboxyl modification, carbinol modification, methacryl modification, mercapto modification, phenol modification, one-end reactivity, and different functional group modification. Examples of the non-reactive silicone oil include polyether modification, methylstyryl modification, alkyl modification, higher fatty acid ester modification, hydrophilic special modification, higher alkoxy modification, higher fatty acid modification, and fluorine modification. Among the above silicone oils, reactive silicone oils of a type having a group that is reactive with the film-forming component may react with and bind to the hydroxyl group of the residue in the acetal resin, and appropriately use a curing agent, a catalyst, or the like. It is also possible to add and use. One or more release agents are used. Moreover, the addition amount of a mold release agent should just be adjusted suitably, but 0.5-10 weight part is preferable with respect to 100 weight part of resin for receiving layer formation normally.

  The dye-receptive layer contains a binder resin, a release agent, a curing agent and a catalyst can be added thereto, and various additives can be added as necessary. Pigments and fillers such as titanium oxide, zinc oxide, kaolin, clay, calcium carbonate, fine powder silica and the like can be added for the purpose of improving the whiteness of the receiving layer and further enhancing the sharpness of the transferred image. Further, a known additive such as a plasticizer, an ultraviolet absorber, a light stabilizer, an antioxidant, a fluorescent whitening agent, and an antistatic agent can be added to the receiving layer as necessary.

The binder resin listed above, the mold release agent listed above, and additives, etc. are optionally added, and kneaded sufficiently with a solvent, diluent, etc. to prepare the receiving layer coating solution. This is applied on the above-mentioned base material by a forming means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, and dried to form a receiving layer. To do. The coating amount of the receiving layer is preferably 0.5g / m ² ~4.0g / m ² in dry. When the coating amount is less than 0.5 g / m ² at the time of drying, unevenness occurs in fixing of the dye, the dye acceptability is lowered, and even if the coating amount is excessive, it is a waste of raw materials, In addition, a lot of drying time is required, and productivity is lowered.

  The thermal transfer image-receiving sheet used in the present invention includes an antistatic layer, a cushion layer, an intermediate layer added with a whitening pigment and a fluorescent whitening agent, and an easy-adhesion layer between the base material and the dye-receiving layer. A layer may be formed.

Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on weight.
Example 1
As a base sheet, a polyethylene terephthalate (PET) film (Mitsubishi Chemical Polyester Film Co., Ltd., Diafoil K203E) having a thickness of 6 μm on one side is used. The dye layer coating solution was applied by gravure coating so that the dry coating amount was 1.0 g / m ² and dried to form a dye layer, whereby a thermal transfer sheet of Example 1 was produced. In addition, the primer layer coating solution for heat-resistant slipping layer having the following composition was previously applied and dried on the other surface of the base sheet so as to have a coating amount of 0.2 g / m ² when dried. The following heat-resistant slipping layer coating solution is applied to the surface of the coating so that the drying temperature becomes 1.0 g / m ² and dried, followed by heat treatment at 60 ° C. for 5 days to form a heat-resistant slipping layer. Oita.

<Dye layer coating solution>
Solvent Blue 63 (cyan dye) 7.0 parts Polyvinyl acetoacetal resin 1 2.1 parts (# 6000-AS, manufactured by Denki Kagaku Kogyo Co., Ltd., degree of acetoacetalization 100% (all acetoacetalized structural units) Number of moles / total number of moles of all acetalized structural units), average degree of polymerization about 2400, Tg 110 ° C.)
0.6 parts of polyvinyl butyral resin 2 (Esreck BM-S, manufactured by Sekisui Chemical Co., Ltd., degree of butyralization 100% (total number of moles of butyralized structural units / total number of moles of all acetalized structural units) ), Number average molecular weight about 53,000, Tg 60 ° C.)
Cellulose resin 1 0.3 parts (Ethylcellulose, Etosel STD45, Nihon Kasei Co., Ltd., ethoxyl group content 45%)
Methyl ethyl ketone 45.0 parts Toluene 45.0 parts

<Primer layer coating solution for heat resistant slipping layer>
10.0 parts of polyester resin (Nichigo Polyester LP-035; manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Methyl ethyl ketone 90.0 parts

<Heat resistant slipping layer coating solution>
13.6 parts of polyvinyl acetoacetal resin (SREC BX-1 manufactured by Sekisui Chemical Co., Ltd.)
0.6 parts of polyisocyanate curing agent (Takenate D218, Takeda Pharmaceutical Company Limited)
Phosphate 0.8 parts (Pricesurf A208N, Daiichi Kogyo Seiyaku Co., Ltd.)
Methyl ethyl ketone 42.5 parts Toluene 42.5 parts

(Examples 2-6, Comparative Examples 1-4)
In the thermal transfer sheet prepared in Example 1, the thermal transfer of Examples 2 to 6 and Comparative Examples 1 to 4 was performed in the same manner as in Example 1 except that the dye layer coating liquid was changed to the composition shown in Table 1. A sheet was produced.
The details of the polyvinyl butyral resin 1 and the cellulose resin 2 used in each dye layer coating solution are as follows.

Polyvinyl butyral resin 1 (ESREC BH-S, manufactured by Sekisui Chemical Co., Ltd., butyralization degree 100% (total number of moles of butyral structural units / total number of moles of all acetalized structural units), number average (Molecular weight about 66000, Tg64 ° C)
Cellulose-based resin 2 (ethyl cellulose, N-50, manufactured by Hercules Co., Ltd., ethoxyl content 48.0 to 49.5, toluene: ethanol = 80: 20) Viscosity 40 to 52 mPa · s when 5% ethyl cellulose was dissolved )

[Evaluation]
1. Evaluation of abnormal transfer and thermal fusion The thermal transfer sheet prepared in each of the above examples and comparative examples was combined with the following thermal transfer image receiving sheet in an environment of 25 ° C. and 50% RH, and was subjected to 15 stages under the following printing conditions. A print with a cyan dye having 15 gradation levels was formed.
(Thermal transfer image receiving sheet)
(1) White vinyl chloride card (a substrate made of vinyl chloride also serves as a dye receiving layer)
(2) PET-G card (A polyester base material comprising a polyethylene terephthalate copolymer of terephthalic acid, ethylene glycol, and cyclohexanedimethanol also serves as a dye-receiving layer.)

(Printing conditions)
Thermal head; KEE-57-12GAN2-STA (manufactured by Kyocera Corporation)
Heating element average resistance value: 3303 (Ω)
Main scanning direction printing density; 300 dpi
Sub-scanning direction print density; 300 dpi
Printing voltage: 18 (V)
1 line cycle; 3.0 (msec.)
Printing start temperature: 35 (℃)
Applied pulse (gradation control method): Using a multi-pulse test printer that can vary the number of divided pulses from 0 to 255 in one line period and having a pulse length obtained by equally dividing one line period into 256 The duty ratio of the divided pulses was fixed to 85%, and the number of pulses per line period, 0 to 255, was divided into 15. Thereby, different energy can be given to 15 steps.

<Evaluation criteria>
Abnormal transfer refers to a phenomenon in which part of the dye layer is transferred to the receiving layer side after printing because the releasability between the dye layer and the receiving layer of the thermal transfer image receiving sheet is poor. Thermal fusion refers to a phenomenon in which the dye layer and the receiving layer cannot be peeled after printing because the releasability between the dye layer and the receiving layer of the thermal transfer image-receiving sheet is poor.
5: No abnormal transfer or thermal fusion occurs.
4: Abnormal transfer occurred in less than 40% of the screen area.
3: Abnormal transfer occurred in 40% to 60% of the stamp screen area.
2: Abnormal transfer occurred at 60% or more of the stamp screen area.
1: Thermal fusion occurs.

2. Evaluation of Adhesion with Substrate Sheet A mending tape MDLP-12 manufactured by Nichiban Co., Ltd. was pasted on the cyan dye layer of the thermal transfer sheet prepared in each Example and Comparative Example, and the tape was peeled at a 180 ° peel angle. Was peeled off, and the adhesion between the substrate sheet and the dye layer was evaluated.
<Evaluation criteria>
○: No dye layer is removed.
X: The dye layer adheres to the tape and peels off.

3. Storage stability of thermal transfer sheet The thermal transfer sheet prepared in each example and comparative example was stored in a 90 ° C. and 90% humidity environment for 96 hours, and then the abnormal transfer evaluation was performed except that the applied pulse was set to 0 on a white vinyl chloride card. Solid printing was performed using the printing conditions, and the printed matter was visually confirmed and evaluated. This is for checking whether the dye is deposited on the surface of the dye layer after leaving the thermal transfer sheet under the above environmental conditions. The thermal transfer sheet having excellent storage stability is printed under the above conditions. A non-printed portion (white portion) having no stain of dye and a thermal transfer sheet having poor storage stability is a printed matter having the above conditions, and the stain of the dye is generated in the non-printed portion.
<Evaluation criteria>
○: No stain on the dye.
X: Dye is dirty.

4). Dye transferability to heat-resistant slipping layer Dye layer and heat-resistant slipping layer of thermal transfer sheet prepared in each example and comparative example are opposed to each other, 20 kg / cm ² load is applied, temperature is 40 ° C. and humidity is 90% RH. It was stored for 96 hours in the environment. The color difference ΔE ^{* ab} of the heat resistant slipping layer before and after storage was determined under the following colorimetric conditions, and the dye transfer property to the heat resistant slipping layer was evaluated.
[Color measurement conditions]
Using a spectrophotometer, the chromaticity values L ^* , a ^* , and b ^* are measured with a white reference as an absolute value, a D65 light source, an observation field of view of 2 °, and a density standard as ANSI STATUS A. ΔE ^{* ab} was determined as follows.
Delta] E * ^ab = (difference between L ^* values of the heat-resistant lubricating layer before and after storage) ² + (difference a ^* value of the heat-resistant lubricating layer before and after storage) ² + (a heat-resistant lubricating layer before and after storage b ^* value Difference) ²

<Evaluation criteria>
A: The color difference ΔE ^{* ab} between the heat-resistant slip layer before and after being stored under load opposite to the dye layer is less than 3.0, which is very good.
○: The color difference ΔE ^{* ab} between the heat-resistant slipping layer before and after being stored under a load facing the dye layer is 3.0 or more and less than 5.0, which is good.
Δ: Color difference ΔE ^{* ab} between the heat-resistant slipping layer before and after being stored under load opposite to the dye layer is 5.0 or more and less than 6.0, which is bad.
X: The color difference ΔE ^{* ab} between the heat-resistant slipping layer before and after being stored under load while facing the dye layer is 6.0 or more, which is very bad.

5. Transfer density Using the thermal transfer sheet prepared in each of the examples and comparative examples, in combination with a white vinyl chloride card, printing was performed under the above-described abnormal transfer evaluation printing conditions, and maximum transfer was performed with the Macbeth reflection densitometer RD-918. Concentration was measured.
<Evaluation criteria>
A: Maximum transfer density is 1.7 or more. O: Maximum transfer density is 1.6 or more and less than 1.7. Δ: Maximum transfer density is 1.5 or more and less than 1.6.

The results of the above evaluations are shown in Table 1.
From the above evaluation results, in the thermal transfer sheets of Examples 1 to 6 according to the present invention using polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin (ethyl cellulose) as the binder of the dye layer, the printing speed is It became clear that the abnormal transfer between the dye layer of the thermal transfer sheet and the material to be transferred and the prevention of thermal fusion were high in the printing while corresponding to the high speed. The thermal transfer sheets of Examples 1 to 6 are also used for the thermal transfer image-receiving sheet (PET-G card) having a non-crystalline polyethylene terephthalate copolymer receiving layer that was easily heat-sealed according to the conventional thermal transfer sheet. Even if no release agent was blended, the abnormal transfer and heat fusion prevention performance was high.

  In addition, in the thermal transfer sheets of Examples 1 to 4 and 6, the adhesion to the base sheet and the storage stability were good, the printing density was excellent, and the color unevenness of the printing was not observed. Only in Example 5, the storage stability of the thermal transfer sheet is slightly lowered. In the dye layer of Example 5, the dye layer binder is composed of three components of polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin (ethyl cellulose). Ethyl cellulose is in the total solid content of the binder in the dye layer. And 20% by weight, and the content ratio is large. In addition, although the dye layer binder of Example 6 consists of three components, a dye layer binder, polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin (ethyl cellulose), polyvinyl butyral resin is the total solid of the binder in a dye layer. In the minute, it is 45% by weight, and the content ratio is large.

  The dye layer of Comparative Example 1 does not contain a polyvinyl butyral resin as a binder and is a two-component polyvinyl acetoacetal resin and a cellulose resin. However, in white vinyl chloride cards, abnormal transfer and thermal fusion are prevented. However, for the PET-G card, heat fusion occurred and the dye layer and the receiving layer were not peeled off, resulting in a portion. Further, the transfer density of the dye layer of Comparative Example 1 was insufficient.

  In addition, the dye layer of Comparative Example 2 is composed of only one component of a cellulose resin as a binder, prevents abnormal transfer and thermal fusion, has releasability, Defects occurred in the storage stability of the thermal transfer sheet and the dye transfer to the heat resistant slipping layer.

  The dye layer of Comparative Example 3 is composed of only one component of polyvinyl acetoacetal resin as a binder, and has good adhesion to the base sheet, storage stability of the thermal transfer sheet, and dye transfer to the heat resistant slipping layer. However, in the white vinyl chloride card, although abnormal transfer and thermal fusion were prevented, thermal fusion occurred in the PET-G card, and the dye layer and the receiving layer were not peeled off. Further, the dye layer of Comparative Example 3 had a low transfer density.

  The dye layer of Comparative Example 4 is composed of only one component of polyvinyl butyral resin as a binder, and has good adhesion to the base sheet, storage stability of the thermal transfer sheet, and dye transfer to the heat-resistant slip layer. Abnormal transfer occurred in both the white vinyl chloride card and the PET-G card.

  From the evaluation results of the above Examples and Comparative Examples, in the thermal transfer sheet of the present invention, the binder in the dye layer is composed of polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin, that is, the dye layer binder is composed of three components. In particular, the polyvinyl acetoacetal resin itself has high dye retention, high storage stability of the thermal transfer sheet, and high function to prevent dye migration to the heat-resistant slipping layer, and the cellulose resin itself is abnormal transfer and thermal fusion. The polyvinyl butyral resin itself has the storage stability of the thermal transfer sheet and the function of high transfer sensitivity. Each of these three-component binder resins separates each other in the dye layer, takes a sea-island structure, and can exhibit the function of each binder resin. In particular, in the total solid content of the binder in the dye layer, the content of the polyvinyl acetoacetal resin is 60 to 80% by weight, the polyvinyl butyral resin is 20 to 30% by weight, and the cellulose resin is 1 to 10% by weight. While supporting high speed, it prevents abnormal transfer and thermal fusion between the dye layer of the thermal transfer sheet and the transfer target in printing, and has good adhesion and storage stability between the base sheet and the dye layer, The printing density is high, and the effect of preventing uneven color printing is high.

It is a schematic sectional drawing which shows one embodiment which is the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows another one Embodiment which is the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows one embodiment which is the thermal transfer recording material of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material sheet 2 Dye layer 3 Heat resistant slipping layer 4 Undercoat layer 10 Thermal transfer sheet 11 Base material 12 Dye receiving layer 20 Thermal transfer image receiving sheet 30 Thermal transfer recording material

Claims (5)

In the thermal transfer sheet in which a heat-resistant slipping layer is provided on one side of the base sheet and a dye layer containing a dye and a binder is provided on the other side of the base sheet, the heat-resistant slipping layer is polyvinyl butyral. Resin and / or polyvinyl acetoacetal resin, the binder in the dye layer contains polyvinyl acetoacetal resin, polyvinyl butyral resin, and cellulose resin ,
In the total solid content of the binder in the dye layer, the polyvinyl acetoacetal resin is contained at 60 to 80% by weight, the polyvinyl butyral resin at 10 to 30% by weight, and the cellulose resin at 1 to 10% by weight. Characteristic thermal transfer sheet. The thermal transfer sheet according to claim 1, wherein the cellulose resin is ethyl cellulose. The thermal transfer sheet according to claim 1 or 2 , wherein the release agent is contained in the dye layer in an amount of 3 parts by weight or less with respect to 100 parts by weight of the total solid content of the dye layer binder. The thermal transfer sheet according to any one of claims 1 to 3 , wherein the weight ratio (D / B) of the total amount (D) of the dye and the total amount (B) of the dye layer binder is 2 to 2.5. . The thermal transfer sheet according to any one of claims 1 to 4 , and a thermal transfer image-receiving sheet provided with a dye-receiving layer on at least one surface of a substrate, wherein the dye layer of the thermal transfer sheet and the dye-receiving of the thermal transfer image-receiving sheet In the thermal transfer recording material in which the layers are superposed and the dye in the dye layer can be transferred to the dye receiving layer by heating means, the dye receiving layer of the thermal transfer image receiving sheet is selected from the group consisting of polyester, polyurethane, and polycarbonate A thermal transfer recording material comprising at least one kind as a main component.

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