JPH06247060A - Heat-sensitive transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a heat-sensitive transfer image receiving sheet, which has high heat resistance and causes no lowering of gloss even at high temperature printing. CONSTITUTION:In the heat-sensitive transfer image receiving sheet concerned produced by laminating precoating layer mainly constituting of polypropylene copolymer resin and image receiving layer mainly constituting of thermoplastic resin on support in the order named, the polypropylene copolymer resin in the copolymer of propylene and one or more kind of compound selected from the group consisting of alkenylsilane and nonconjugative diene and treated so as to have the gel fraction thermally extracted with m-xylene of 20% or more. Due to high gel fraction at elevated temperature, the polypropylene copolymer resin causes no thermal shrinkage, resulting in obtaining heat-sensitive transfer image receiving sheet, which causes neither lowering of gloss at printing and nor blocking with donor sheet.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a precoat layer having a high smoothness and a polypropylene copolymer resin having a high temperature gel component as a main component, the image receiving layer being coated on the support, The present invention relates to a heat-sensitive transfer image-receiving sheet having high image quality and excellent gloss in an image area.

[0002]

2. Description of the Related Art As a means for color hard copy, a sublimation-type thermal transfer printer is particularly used for reproducing multicolor gradation images. The principle of such a sublimation-type thermal transfer printer is to convert an image into an electric signal, and further convert the electric signal into a heat signal by a thermal head to apply a sublimation-type ink (ink donor sheet). Is heated and the sublimated ink is fixed by an image receiving paper that is in close contact with the ink donor sheet, and the image is reproduced. The surface of such an image receiving paper is generally provided with an image receiving layer for fixing the ink with a polymer such as saturated copolyester and polyacetate.

In the sublimation type thermal transfer type printer, there has recently been a demand for higher printing speed and improved transfer image quality. When a porous support such as plain paper is used as the support for the image-receiving sheet for thermal transfer, the smoothness is low and the image quality is poor. In order to obtain a transferred image with high image quality without image unevenness, it is preferable that the image receiving layer has a high surface smoothness, and a Beck smoothness of at least 20.
It is required to be 00 seconds or longer, preferably 5000 seconds or longer. In order to improve the quality of transferred images, coated paper such as art paper and coated paper, synthetic resin film such as polyethylene, polypropylene, polypropylene terephthalate, polymethylpentene, vinyl chloride, vinylidene chloride, polystyrene and polyamide, or their synthesis It is unavoidable to use laminated paper in which resin is laminated on one side or both sides, synthetic paper, or the like.

However, in art paper and coated paper,
Even if an image receiving layer is provided thereon, the smoothness may be slightly lacked and the gloss tends to be poor. As the support, a support obtained by laminating synthetic resin film or synthetic resin on paper is used.
It can be said that it is excellent in terms of gloss and smoothness. Among them, particularly, the support used as a precoat layer by laminating polyethylene on paper by melt extrusion is laminated with other synthetic resin, as can be seen from the actual results used as a support in the present silver salt photography. It is cheaper and superior in laminating suitability, easy to manufacture, high gloss, firmness as a support, high surface smoothness, and not limited to water-based or organic solvent-based image-receiving layer coating liquid. It is an excellent image-receiving paper support having excellent adhesion to the image-receiving layer. However, when melt-extruded polyethylene is used as the precoat layer, since polyethylene has poor heat resistance, shrinkage due to heat of the thermal head occurs in combination with its high smoothness, and surface properties (particularly, fine wrinkles in the printed portion, In some cases, the non-gel component causes blocking with the ink donor sheet at a high temperature, resulting in deterioration of image quality.
In particular, this phenomenon tends to increase the printing speed, and when the thermal printing temperature inevitably increases, the above situation tends to be exacerbated. When polypropylene was used instead of polyethylene, the heat resistance was better than that of polyethylene, but it was still not sufficient.

[0005]

Therefore, the problem to be solved by the present invention is that a sublimation type thermal transfer image-receiving paper using a polypropylene copolymer resin layer laminated on a support by melt extrusion as a precoat layer has a high heat resistance. An object of the present invention is to provide an image-receiving sheet for heat-sensitive transfer capable of obtaining a good recorded image without lowering gloss and image quality even when the printing temperature is used.

[0006]

[Means for Solving the Problems] As a result of earnest research on means for solving the above problems, the following method has been found. That is, in a heat-sensitive transfer image-receiving sheet obtained by laminating a precoat layer containing a polypropylene copolymer resin as a main component and an image receiving layer containing a thermoplastic resin as a main component on a support, the polypropylene copolymer resin is propylene. And alkenylsilane or non-conjugated diene 1
It is a copolymer with more than one kind of compound, and the thermal m-xylene extraction gel fraction of the precoat layer is 2 by one or more kinds selected from a light irradiation method, an electron beam irradiation method and a heating method.
It is an invention of an image-receiving sheet for heat-sensitive transfer characterized by being cross-linked to 0% or more. The polypropylene copolymer resin is a copolymer of propylene and one or more kinds of compounds selected from alkenylsilanes and non-conjugated dienes, and may contain ethylene as a copolymer component. The precoat layer can include white pigments or voids.
That is, the present invention is a support capable of increasing the high temperature gel component of the polypropylene copolymer resin provided on the support by any method, and suppressing the decrease in gloss and the occurrence of blocking during thermal transfer recording. And a thermoplastic resin layer is applied onto the precoat layer to obtain a heat-sensitive transfer image-receiving sheet having excellent heat resistance.

The present invention will be described in detail below.

From the viewpoint of heat resistance, the polypropylene copolymer resin used in the present invention is a copolymer of alkenylsilane mainly composed of propylene, or a copolymer of propylene, alkenylsilane and ethylene, or It is a copolymer of propylene as a main component with a non-conjugated diene, or a copolymer of propylene resin with a non-conjugated diene and ethylene. Further, a ternary copolymer of propylene and alkenyl silane, a non-conjugated diene, or a quaternary copolymer of propylene and alkenyl silane, a non-conjugated diene and ethylene may be used. In the polymerized form, any structure such as isotactic, syndiotactic, atactic, etc. may be used. It is also possible to melt-extrude and laminate it on a support, or it is also possible to laminate an unstretched or stretched film by laminating it with a support. In laminating by laminating, it may be used in the form of a porous film or a foamed film. When laminating, general polypropylene, polyethylene and polymethylpentene (TP
It is also possible to mix and use other polyolefin resins such as X). In general polypropylene used by mixing, homopolymer, copolymer, terpolymer, etc.
There is no particular limitation. These unlaminated resins have many non-gel components at high temperature when they are uncrosslinked (almost 100% are non-gel components in uncrosslinked treatment), and they have fluidity in the high temperature region near the melting point, which is It adversely affects gloss and image quality.

As a method of reducing the high temperature non-gel component of the polypropylene copolymer resin constituting the precoat, a method of kneading a polyfunctional monomer and reacting it by heating,
Similarly, a method in which a polyfunctional monomer and a sensitizer are kneaded and reacted by light, a method in which light is irradiated in chlorine gas or acetylene gas to introduce a chloro group or a vinyl group to react with a polyfunctional monomer, and a dilute acetylene gas By plasma discharge in order to react with ozone, a method of reacting with a polyfunctional monomer having an allyl group or acryloyl group after being oxidized with ozone, and a sensitizer such as benzophenone or N-methyl-2-benzoyl-β-naphthiazoline is kneaded and irradiated with light to induce intramolecular reaction. There may be many methods such as a method of reacting the unsaturated bond, a method of graft-reacting a radical generated by light irradiation or γ-ray or electron beam irradiation with a monomer such as acrylic acid.

[0010] Polyethylene-based resins are used in the method of crosslinking by electron beam irradiation in terms of uniformity and easiness of reaction, but in the case of polypropylene-based resins, electron beams are used. It is known that the decomposition proceeds by irradiation, and the heat resistance is further reduced by simply irradiating the electron beam.

However, as shown by the present invention, as a polypropylene copolymer resin, a copolymer of propylene with alkenylsilane as a main component, or a copolymer of propylene with alkenylsilane and ethylene, or propylene as a main component. When a copolymer of a non-conjugated diene or a copolymer of a propylene resin, a non-conjugated diene and ethylene is used as a resin for the precoat layer, not only electron beam irradiation but also light irradiation and heat curing It was revealed that the cross-linking structure can be eliminated by the method, and the precoat layer having a cross-linking structure of a certain limit or more is very excellent for the sublimation type thermal transfer image-receiving layer.

The non-conjugated diene used as a copolymerization component in the present invention is, for example, 1,4-pentadiene, 1,4-
Hexadiene, 5 methyl-1,4-hexadiene, 1,
5-hexadiene, 1,5-heptadiene, 6-methyl-
1,5-heptadiene and the like, which are generally copolymerizable with propylene in the presence of a Ziegler catalyst. When copolymerized, one double bond remains in the side chain and has a crosslinking effect. The polymerization ratio of the non-conjugated diene is 0.5 to 10 mol% when copolymerized with propylene and ethylene components.
If the non-conjugated diene is less than this range, the cross-linking effect is not sufficient, and there is a problem in heat resistance and high temperature type retention, and if it is more than this range, uniform copolymerization becomes difficult and exfoliation occurs. And the effect of improving crosslinkability do not become better than a certain limit, which is economically disadvantageous.

The alkenylsilane used as the copolymerization component in the present invention is, for example, vinylsilane or vinylalkyl or vinyldialkylsilane compound such as vinylmethylsilane, vinylethylsilane, vinylpropylsilane, vinyldimethylsilane, etc. It can be easily copolymerized with an olefin compound in the presence of a Ziegler catalyst. The polymerization ratio of the alkenylsilane is within the range of 0.03 to 5 mol% when copolymerized with the propylene and ethylene components. If the amount of the alkenylsilane is less than this range, the crosslinking effect is not sufficient and the heat resistance and high temperature are high. There is a problem in mold retention, and if it exceeds this range, uniform copolymerization becomes difficult, and the effect of improving releasability and crosslinkability does not become better than a certain limit, which is economically disadvantageous.

In the precoat layer used in the present invention, a polypropylene copolymer resin is used as a main component, but an ethylene component is introduced in a form of copolymerizing with a propylene component, or blended with a polypropylene copolymer resin component. It is preferable to introduce the polyethylene component in such a form that the laminating suitability is improved. In this case, the molar ratio of the ethylene component to the propylene component is preferably 3: 1 or less. This is because when the ethylene component is more than this ratio, not only does it not contribute to the effect of improving the suitability for lamination, but also the heat resistance may decrease.

White pigments such as titanium oxide, zinc oxide, talc and calcium carbonate may be added to the precoat layer of the present invention for the purpose of improving the whiteness and image sharpness of the heat-sensitive transfer image-receiving sheet. it can. Furthermore, in the precoat layer of the present invention, a blue dye or pigment for color tone adjustment,
Various additives such as an antioxidant, a fluorescent whitening agent, an antistatic agent, a dispersant, a stabilizer, an ultraviolet absorber and an adhesion promoter can be appropriately combined and added.

The precoat layer according to the present invention is most preferably prepared by laminating a polypropylene copolymer resin of the present invention alone or in a mixture and laminating it on a support by melt extrusion to form a precoat layer. It is also possible to form a sheet by a means such as the above and then bond it to a support.
In this case, the crosslinking treatment may be performed before or after the bonding.

When using an electron beam, the amount of the electron beam to be irradiated is preferably adjusted within the range of about 0.5 to 30 Mrad in the absorbed dose to the polypropylene copolymer resin. A sufficient irradiation effect cannot be obtained at 0.5 Mrad or less, and even if the electron beam irradiation amount is increased above 30 Mrad, the crosslinking level and heat resistance of the polypropylene copolymer resin are hardly changed, and the paper or film support is deteriorated. Therefore, it is not preferable. As the electron beam irradiation method, a scanning method, a curtain beam method, or the like is adopted, and an accelerating voltage for irradiating the electron beam is preferably about 100 to 300 KV. Although the same treatment as electron beam irradiation can be performed using γ rays, the dose density is generally low, which is not preferable as a manufacturing method. When ultraviolet rays are used for crosslinking, a photoinitiator and, if necessary, a sensitizer are added. When ultraviolet rays are used, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, a tungsten lamp, etc. are preferably used.

It is an essential condition that the polypropylene copolymer resin used in the present invention has a thermal m-xylene extraction gel fraction of 20% or more when used as a precoat layer. The hot m-xylene-extracted gel fraction as used herein means the gel fraction when the polypropylene copolymer resin is extracted with hot m-xylene at the boiling point for 2 hours, and is a value obtained by the following method. . In the case of a heat-sensitive transfer image-receiving sheet, only 1 g of polypropylene copolymer resin in the precoat layer (A: the amount of polypropylene copolymer resin used) was separated and cut into several sheets, and then the standard maximum aperture was 1
Put in a glass filter of 6-40 μm (Shibata Kagaku Kikai Kogyo Co., Ltd., G3.5 in pore number), put in a sufficient amount of boiling hot m-xylene together with the glass filter and shake for 2 hours. When a component soluble in hot m-xylene is extracted with a hot m-xylene and then dried in vacuum, the amount of polypropylene copolymer resin remaining without being dissolved in hot m-xylene (B: residual amount of polypropylene copolymer resin) It is a value obtained by the following Expression 1.

[0019]

[Equation 1] Gel fraction (%) = 100 × B / A A: Amount of polypropylene copolymer resin used (g) B: Remaining amount of polypropylene copolymer resin (g)

As a matter of course, when the polypropylene copolymer resin contains an inorganic substance such as titanium oxide or zinc oxide, or a polymer other than the polypropylene copolymer, the weight is subtracted from the calculated value. I do. Regardless of the type of polypropylene, the thermal m-xylene extraction gel fraction when treated for 2 hours is a value of 1% or less as long as it is measured in the state where crosslinking is not performed.

In the present invention, the image quality of the image-receiving sheet for thermal transfer is improved because the gel fraction of the polypropylene copolymer resin forming the precoat layer plays a large role.
The fact that this improvement in image quality does not depend solely on the superiority or inferiority of the melting property of polypropylene means that the polypropylene copolymer resin precoat layer of the present invention in which the effect of improving image quality by electron beam irradiation is clearly recognized. It was also confirmed from the fact that the melting point range in thermal analysis and the heat of fusion per unit weight in the polypropylene copolymer resin precoat layer before irradiation hardly changed, and in the recording at high temperature, the melting point of the polypropylene copolymer resin was However, it can be seen that the image quality is not so affected.

Examples of the thermoplastic resin used in the image-receiving layer of the present invention include those having an ester bond such as polyester resin, polyacrylic acid ester resin,
Polycarbonate resins, polyvinyl acetate resins, styrene acrylate resins, etc. are available. Polyurethane resins having urethane bonds, polyamide resins (nylon), urea having amide bonds, etc. As a resin having a bond, a urea resin or the like can be used, and a copolymer containing one or more kinds of the above structural units of the resin as a main component,
For example, vinyl chloride-vinyl acetate copolymer, styrene-
It can also be used as a butadiene copolymer or the like, and the above resins can be used alone or in combination of two or more kinds. Any of the above thermoplastic resins can be preferably used for the purpose of the present invention, but in particular, for the purpose of increasing dyeability of sublimation dyes and measuring transfer density, polyester such as linear saturated polyester resin is used. Resins are preferred.

The above-mentioned thermoplastic resin may be dissolved in an organic solvent and applied on the substrate, or emulsified in an aqueous solution and applied on the substrate as an emulsion. Further, if necessary, an additive such as a dye, a pigment, a wetting agent, a defoaming agent, a dispersant, an antistatic agent, a release agent and a fluorescent brightening agent may be contained. In particular, regarding the pigment, the purpose of improving blocking can be achieved by incorporating inorganic particles typified by silica, calcium carbonate, kaolin clay, barium sulfate, titanium oxide and the like into the thermoplastic resin layer.

Further, a releasing agent can be used for the same purpose. Specifically, solid waxes such as polyethylene wax and amide wax, phosphoric ester type surfactants, silicone oil, Teflon powder, Fluorine-based and silicone-based compounds such as silicone powder can be used. However, curable silicone compounds are preferably used because it is difficult for blurring of transferred dye and transfer or reduction in image density to occur.

Examples of the curable silicone compound include a thermal reaction curable type, an ultraviolet curable type, an electron beam curable type and a catalyst curable type, which have an affinity with the image receiving layer component, a releasability from a donor sheet, and a sublimation. It can be appropriately selected and used depending on its affinity with the type dye. These release agents can be used by being dispersed in the image receiving layer, or can be provided as a top coat layer on the image receiving layer. When provided as a top coat, for the purpose of improving the sensitivity of the image receiving layer,
A thermoplastic resin such as a linear polyester resin can be used together with the release agent.

As the support used in the present invention, in addition to plain paper base paper, non-woven fabric, art paper, coated paper such as coat paper, synthetic resin film, synthetic paper and the like are used.

In the present invention, the base paper used as the paper support is ordinary natural pulp paper such as glassine paper, high-quality paper, coated paper, synthetic fiber, or so-called synthetic paper obtained by simulating synthetic resin film. Although it can be used, a natural pulp paper containing wood pulp of a softwood pulp, a hardwood pulp, and a mixed hardwood pulp as a main component is advantageously used. The thickness of the base paper is not particularly limited, but a smooth one is preferable, and its basis weight is preferably 30 to 300 g / m ² .

In the method of the present invention, the base paper containing natural pulp as a main component, which is advantageously used, may contain various polymer compounds and additives. For example, starch, starch derivatives (cationized starch, phosphate esterified starch, oxidized starch, etc.), polyacrylamide, polyvinyl alcohol, polyvinyl alcohol derivatives (complete saponification, partial saponification, carboxy modification, cation modification, and other various modifications). Polyvinyl alcohol),
Gelatin (alkali treatment, acid treatment, various modified gelatin)
Dry paper strengthening agents such as, natural polymeric polysaccharides such as star gum and alginic acid derivatives, higher fatty acid metal salts, rosin derivatives, dialkyl ketones, alkenyl or alkyl succinic anhydrides, epoxidized higher fatty acid amides, organic fluoro compounds, dialkyls Ketene dimer emulsion sizing agent, polyamide polyamine epichlorohydrin resin, melamine resin, urea resin, epoxidized polyamide resin, etc. wet paper strength enhancer, stabilizer, pigment, dye, antioxidant, optical brightener, various latex , Inorganic electrolytes (sodium chloride, sodium sulfate, sodium phosphate, calcium chloride, lithium chloride, magnesium chloride, magnesium sulfate, barium chloride, etc.), pH adjusting agents, fixing agents such as sulfuric acid bands and aluminum chloride, calcium carbonate, kaolin, Filler such as talc, clay, etc. Additives of the conductive agent and the like can be incorporated appropriately combined. These contents may be dispersed in the pulp slurry at the papermaking stage, or may be added at the tab size after papermaking,
Further, the solution may be applied with various coaters.

Examples of the method for applying the thermoplastic resin on the substrate include blade coating, air doctor coating, squeeze coating, air knife coating, reverse roll coating, gravure roll and transfer roll coating, bar coating and curtain coating. A method is used.

The polypropylene copolymer resin used in the present invention may contain a polyfunctional monomer having an unsaturated bond which can be polymerized by heat, electron beams or ultraviolet rays to promote crosslinking. Such a polyfunctional monomer is a compound having one or more carbon-carbon unsaturated bonds, and specifically includes an acryloyl group, a methacryloyl group, an acrylamide group, an allyl group, a vinyl ether group, a vinyl thioether group, and the like. Compounds, for example, acrylic acid alkyl ester, methacrylic acid alkyl ester, acrylonitrile, methacrylonitrile,
Examples thereof include acrylamide, vinyl acetate, vinyl propionate, vinylpyrrolidone and the like. There may be two or more unsaturated bonds in the molecule. In particular, unsaturated esters of polyols such as ethylene diacrylate, diethylene glycol diacrylate, glycerol triacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate and the like can be mentioned. Further, a compound having one or more epoxy rings,
For example, glycidyl acrylate and the like are also preferable. Furthermore,
These compounds may be high molecular weight compounds. Particularly preferred is a compound having an acrylate group at the terminal or side chain of the polymer chain, and examples thereof include a polyester skeleton, a polyurethane skeleton, an epoxy resin skeleton, a polyether skeleton, a polycarbonate skeleton, and a prepolymer having a silicone skeleton. These monomers and prepolymers may be used alone or as a mixture. Further, a polymerization initiator such as a peroxide can be used in combination for the purpose of promoting the thermal reaction.

In the present invention, as the photoinitiator used when treating the polypropylene copolymer resin by ultraviolet irradiation, acetophenones such as di- or trichloroacetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin alkyl ether, There are benzyl dimethyl ketal, tetramethyl thiuram monosulfide, thioxanthones, azo compounds, etc., and the curing reaction type and stability of UV curable resin,
Also, it is selected from the viewpoint of suitability with an ultraviolet irradiation device. The amount of the photoinitiator used is usually, with respect to the ultraviolet curable resin,
It is in the range of 0.1 to 5%. Further, a storage stabilizer such as hydroquinone may be used in combination with the photoinitiator.

As the sensitizer used in the present invention, an aliphatic amine, an amine containing an aromatic group, a nitrogen heterocyclic compound,
Allyl urea, O-tolylthiourea, sodium diethyldithiophosphate, soluble salts of aromatic sulfinic acid,
Photo-initiated with N, N-disubstituted-P-aminobenzonitrile compounds, tri-n-butylphosphine, sodium diethylthiophosphate, Michler's ketone, N-nitrosohydroxylamine derivatives, oxazoline compounds, carbon tetrachloride, hexachloroethane, etc. In general, the curing rate can be improved by sharing it with the agent.

As the light source used for the treatment by ultraviolet irradiation, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, a tungsten lamp, etc. are preferably used.

[0034]

The present invention provides a heat-sensitive transfer image-receiving sheet comprising a support and a precoat layer containing a polypropylene copolymer resin as a main component and an image-receiving layer containing a thermoplastic resin as a main component. The copolymer resin is propylene,
It is a copolymer with one or more compounds selected from alkenylsilanes or non-conjugated dienes, and the precoat layer is prepared by one or more methods selected from a light irradiation method, an electron beam irradiation method and a heating method. The thermal m-xylene extraction gel fraction of
The invention is an image-receiving sheet for heat-sensitive transfer, which is characterized in that it is cross-linked in an amount of at least%. By using the polypropylene copolymer resin as in the present invention, the high temperature non-gel component of the polypropylene copolymer resin at high temperature is reduced, and it is possible to suppress the decrease in gloss and the occurrence of blocking during thermal transfer recording. That is, in the present invention, the precoat layer of the polypropylene copolymer resin provided on the support is increased in the gel component by any method, and the thermoplastic resin layer is applied on the precoat layer to obtain a gloss property. , To obtain an image-receiving sheet for heat-sensitive transfer having excellent imageability and heat resistance.

[0035]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples.

Example 1 After performing corona discharge treatment on an art paper having a basis weight of 175 g / m ² , 10 wt% titanium oxide and 0.1 wt% polyfunctional silicone resin {1 , 3-
Polypropylene copolymer resin containing bis (3-methacryloxypropyl) tetrakis (trimethylsiloxy) disiloxane} (propylene and a non-conjugated diene; a copolymer of 5-methyl-1,4 hexadiene, the non-conjugated diene 1 mol%) and melt-extruded laminate at 25 g /
A precoat layer was formed by laminating with m ² .
The support having the precoat layer was irradiated with an electron beam (accelerating voltage: 200 KV, absorbed dose of about 0.5 Mrad) to adjust the gel fraction of the polypropylene copolymer resin to 60%. Polyester resin emulsion (Vylonal MD-13 with air knife coater on the precoat layer.
30: Toyobo Co., Ltd. and silica with dry solids of 3.0 g each
/ M ² and 0.5 g / m ² to obtain an image-receiving sheet for thermal transfer by coating and drying.

Example 2 An image-receiving sheet for thermal transfer was obtained in the same manner as in Example 1 except that the absorbed dose of the polypropylene copolymer resin by electron beam irradiation was about 2 Mrad and the gel fraction was 90%.

Example 3 After performing corona discharge treatment on an art paper having a basis weight of 175 g / m ² , a polypropylene copolymer resin containing 10% by weight of titanium oxide by a melt extruder (copolymer of propylene and vinylsilane) When combined, the vinylsilane was melt-extruded and laminated at 1 mol% of the total) at a laminating amount of 25 g / m ^{2 to} form a precoat layer. The support having this precoat layer was irradiated with electron beams (accelerating voltage: 200
KV, absorbed dose of about 5 Mrad) was performed to adjust the gel fraction of the polypropylene copolymer resin to 80%. On the pre-coat layer, a polyester resin (Vylon 200: Toyobo) and silica with a gravure coater and a dry solid content of 3.
An image receiving sheet for heat-sensitive transfer was obtained by applying as an ethyl acetate solution and drying it so as to have an amount of 0 g / m ² and 0.5 g / m ² .

Example 4 After performing corona discharge treatment on an art paper having a basis weight of 175 g / m ² , a polypropylene copolymer resin (propylene, ethylene, and vinylsilane) containing 10% by weight of titanium oxide was prepared by a melt extruder. The copolymer was subjected to melt extrusion lamination with a resin having a molar ratio of propylene: ethylene = 95: 5 and vinylsilane of 0.05 mol% of the whole) at a laminating amount of 25 g / m ² . The laminated base material is irradiated with ultraviolet rays from a medium-pressure mercury lamp to cross-link the laminated resin, and the cross-linked pre-coated
I got a layer. The hot m-xylene extraction gel fraction of the laminate resin after ultraviolet irradiation was 30%. An image receiving layer was provided in the same manner as in Example 3 to obtain an image receiving sheet for thermal transfer.

Example 5 The same support as in Example 1 was subjected to corona discharge treatment,
Polypropylene copolymer resin containing 10% by weight of barium sulfate (copolymer of propylene and vinyl silane, vinyl silane is 1 mol% of the total), low density polyethylene 5% by weight, solventless thermosetting silicone resin ( Tore Silicone Co., Ltd., trade name BY14-407 is mixed with a low temperature curing type catalyst (trade name BY14-408CAT, 1% relative to silicone resin) in a weight ratio of 1%, and a melt-extruded laminate is 25 g / m 2. A lamination amount of ² was applied to form a precoat layer. The laminated base material was aged at 80 ° C. for 1 day for crosslinking, and the thermal m-xylene extraction gel fraction was set to 40%. An image receiving layer was provided in the same manner as in Example 3 to obtain an image receiving sheet for thermal transfer.

Example 6 After carrying out corona discharge treatment on the same support as in Example 1,
Melt extrusion lamination was carried out with a resin of a copolymer of propylene and vinyl silane (vinyl silane was 0.1 mol% of the total) at a laminating amount of 25 g / m ² to obtain a precoat layer. The precoat layer was irradiated with ultraviolet rays from a medium-pressure mercury lamp to crosslink the precoat layer, and the thermal m-xylene extraction gel fraction was set to 20%. An image receiving layer was provided in the same manner as in Example 3 to obtain an image receiving sheet for thermal transfer.

Example 7 As a resin for forming a precoat layer, a copolymer of propylene and a non-conjugated diene (non-conjugated diene; 5-methyl-1,
4-hexadiene is 0.5 mol% of the total resin 30 μ
A biaxially stretched film having a thickness of m was produced. An electron beam curable resin (manufactured by Toagosei Kagaku Kogyo Co., Ltd., Aronix M1210 and M1) was used, using a support similar to that of Example 1.
13 in a weight ratio of 7: 3) is applied by a gravure roll in an amount of 20 g / m ² and laminated with a biaxially stretched film,
At a accelerating voltage of 250 kv, electron beam irradiation was performed so that the absorbed dose was 5 Mrad to obtain a support having a crosslinked precoat layer. The hot m-xylene extraction gel fraction of the laminate resin after this electron beam irradiation was 75%. An image receiving layer was provided in the same manner as in Example 1 to obtain an image receiving sheet for thermal transfer.

Comparative Example 1 The same art paper as in Example 1 was used as the support.
After subjecting the surface to corona treatment, melt extrusion lamination with homopolypropylene was performed at a laminating amount of 25 g / m ² . The hot m-xylene extraction gel fraction of this polypropylene was 1%. As in Example 1, pleth
A polyester resin emulsion (Vylonal MD-1330: Toyobo) and silica on an air-knife coater having a dry solid content of 3.0 g / m ² and 0.5 g /
An image receiving sheet for heat-sensitive transfer was obtained by coating and drying so as to be m ² .

Comparative Example 2 The same procedure as in Comparative Example 1 was carried out except that the same homopolypropylene as in Comparative Example 1 was laminated, and then the electron beam irradiation was performed at an acceleration voltage of 250 kv so that the absorbed dose was 5 Mrad. An image receiving sheet for thermal transfer was obtained. The hot m-xylene extraction gel fraction of the laminate resin after this electron beam irradiation was 0%.

Comparative Example 3 The same art paper as in Example 1 was used as the support.
After the surface was subjected to corona treatment, melt extrusion lamination with a copolymer resin of propylene and ethylene (molar ratio: 95: 5) was performed at a laminating amount of 25 g / m ² . The laminated base material was irradiated with ultraviolet rays from a medium-pressure mercury lamp to obtain a mold release material for mirror-shaped molding. The thermal m-xylene extraction gel fraction of the laminate resin after ultraviolet irradiation was 1%. An image receiving layer was provided in the same manner as in Example 3 to obtain an image receiving sheet for thermal transfer.

Comparative Example 4 The same support as in Example 1 was subjected to corona discharge treatment,
Melt extrusion lamination was performed with a resin of a copolymer of propylene and vinyl silane (vinyl silane was 0.05 mol% of the total) at a laminating amount of 25 g / m ² to obtain a precoat layer. The precoat layer was irradiated with ultraviolet rays from a medium-pressure mercury lamp to crosslink the precoat layer, and the thermal m-xylene extraction gel fraction was set to 10%. An image receiving layer was provided in the same manner as in Example 3 to obtain an image receiving sheet for thermal transfer.

Test The ink-sensitive sheet was attached to the image-receiving sheet for thermal transfer thus obtained.
The heating head and the heating time can be freely set, and a fixed area (1 cm x 2.5 c
m) was printed. The temperature at which wrinkles were generated on the surface of the precoat layer for each sample at a heating time of 0.5 seconds was used as a measure of heat resistance. The surface gloss of the cyan print at 200 ° C. was measured with a gloss meter and evaluated as gloss.
The presence or absence of blocking was visually determined. The gloss was evaluated by relative evaluation, with one having excellent gloss being rated as O, one having poor gloss being rated as X, and one being in the middle being rated as Δ.
With respect to blocking, a state in which nothing was observed was evaluated as ◯, and a state in which it was completely observed was evaluated as ×, and the results are shown in Table 1.

[0048]

[Table 1]

Evaluation In the examples, since the gel content of the polypropylene copolymer resin in the precoat layer is high, the fusible content is small in high-temperature printing, blocking with the donor sheet is prevented, and thermal contraction of polypropylene is also suppressed. Therefore, fine wrinkles do not occur, and therefore gloss does not decrease even after image transfer. In the comparative example, since the gel fraction in polypropylene of the precoat layer is low, the heat resistance is low,
Although it may be reduced by lowering the printing gloss or by using a silicone compound, blocking is generally likely to occur.

[0050]

INDUSTRIAL APPLICABILITY In the present invention, a thermoplastic resin and a precoat layer mainly composed of a polypropylene copolymer resin having a hot m-xylene extraction gel fraction of 20% or more melt-extruded on a support are provided. An image-receiving sheet for heat-sensitive transfer, which is formed by laminating an image-receiving layer as a main component, and has a precoat layer, so that it has good smoothness and cushioning properties, good adhesion between the image-receiving layer and the ink donor sheet, and polypropylene copolymerization. Since the non-gel component of the resin at high temperature is reduced compared to untreated polypropylene due to proper cross-linking,
At the time of thermal transfer recording, it is possible to suppress deterioration of gloss and occurrence of blocking.

Claims (3)

[Claims] 1. A heat-sensitive transfer image-receiving sheet comprising a support and a precoat layer containing a polypropylene copolymer resin as a main component and an image-receiving layer containing a thermoplastic resin as a main component. The resin is a copolymer of propylene and one or more compounds selected from alkenylsilanes or non-conjugated dienes, and is prepared by one or more methods selected from a light irradiation method, an electron beam irradiation method and a heating method. An image-receiving sheet for heat-sensitive transfer, characterized in that the pre-coat layer has a thermal m-xylene extraction gel fraction crosslinked to 20% or more. 2. The polypropylene copolymer resin is a copolymer of propylene and one or more compounds selected from alkenylsilane and non-conjugated dienes, and contains ethylene as a copolymer component. The image-receiving sheet for heat-sensitive transfer according to claim 1. 3. The heat-sensitive transfer image-receiving sheet according to claim 1, wherein the precoat layer contains a white pigment.