JP2001047753A - Thermal transfer sheet and image-forming material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which prevents stain of rolls on the occasion of carrying the sheet and enables formation of an excellent image. SOLUTION: In a thermal transfer sheet having at least one photo-thermal conversion layer 14 and at least one image-forming layer 16 on a substrate, a static friction coefficient of the outermost surface layer on the side whereon the image-forming layer 16 is provided by coating is made 0.35 or below. For this thermal transfer sheet 10, a mode wherein the static friction coefficient is 0.20 or below, a mode wherein the outermost surface layer 16 is the image- forming layer, a mode wherein the photo-thermal conversion layer 14 contains an infrared ray absorbing dye, a mode wherein the outermost surface layer 16 contains a monoester of a 9-27C aliphatic acid and alcohol having 2-5 OH radicals and a mode wherein an image is formed by imagewise exposure by using a laser having a wavelength of 750 nm or above are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet used for an image forming method for forming a high-resolution image using a laser beam, and an image forming material using the same.
In particular, the present invention relates to a thermal transfer sheet useful for producing a color proof (DDCP: direct digital color proof) or a mask image in the printing field by laser recording from a digital image signal, and an image forming material using the same. About.

[0002]

2. Description of the Related Art In the field of graphic arts, a printing plate is printed using a set of color separation films produced from a color original using a lithographic film. In order to check for errors in the color separation process and the necessity of color correction, a color proof is made from the color separation film. A color proof is desired to have high resolution which enables high reproducibility of a halftone image and high performance such as high process stability. In addition, in order to obtain a color proof similar to an actual printed matter, as a material used for a color proof, a material used for an actual printed matter, for example, a printing paper as a base material and a pigment as a coloring material are used. Is preferred. Also,
As a method for producing a color proof, there is a high demand for a dry method using no developer.

As a dry-type color proofing method, a recording system for directly producing a color proof from a digital signal has been developed with the recent spread of an electronic system in a pre-printing process (prepress field). The purpose of such an electronic system is to produce a color proof of high image quality, and generally reproduces a halftone image of 150 lines / inch or more. In order to record a proof of high image quality from a digital signal, a laser beam that can be modulated by the digital signal and can narrow down the recording light is used as a recording head. For this reason, it is necessary to develop a recording material that exhibits high recording sensitivity to laser light and high resolution that enables high-definition halftone dots to be reproduced.

As a recording material used in a transfer image forming method using a laser beam, a photothermal conversion layer that absorbs a laser beam and generates heat, a wax and a binder in which a pigment is thermally fusible, and the like are provided on a support. (See Japanese Patent Laid-Open No. 5-58)
No. 045). In the image forming method using these recording materials, the heat generated in the laser light irradiation area of the light-to-heat conversion layer melts the image forming layer corresponding to the area, and is transferred onto the image receiving sheet stacked on the transfer sheet. Then, a transfer image is formed on the image receiving sheet.

Japanese Patent Application Laid-Open No. 6-219052 discloses that a light-to-heat conversion layer containing a light-to-heat conversion substance, a very thin (0.03-0.3 μm) heat-peeling layer, and a coloring material are provided on a support. There is disclosed a thermal transfer sheet provided with image forming layers in this order. In this thermal transfer sheet, by being irradiated with laser light, the bonding force between the image forming layer and the light-to-heat conversion layer that are bonded by the interposition of the thermal release layer is reduced, and the thermal transfer sheet is laminated on the thermal transfer sheet. On the image receiving sheet,
A high-definition image is formed. The image forming method using the thermal transfer sheet utilizes so-called "ablation". Specifically, in a region irradiated with a laser beam, the heat release layer partially decomposes and evaporates. This utilizes a phenomenon in which the bonding force between the image forming layer and the light-to-heat conversion layer is weakened, and the image forming layer in that region is transferred to the image receiving sheet laminated thereon.

In these image forming methods, a printing paper having an image receiving layer (adhesive layer) attached thereto can be used as an image receiving sheet material, and a multicolor image is transferred by successively transferring images of different colors onto the image receiving sheet. It has advantages such as being easily obtained. In particular, the image forming method using ablation has an advantage that a high-definition image can be easily obtained, and produces a color proof (DDCP: direct digital color proof) or a high-definition mask image. Useful for

[0007] However, the thermal transfer sheet is often conveyed in a roll during a coating step or a processing step during manufacturing, or during use by a user. At this time, the surface of the thermal transfer sheet may peel off and adhere to the roll surface. There is. The deposits adhere to the next-transferred thermal transfer sheet, causing image contamination. As a countermeasure, a method of providing a protective layer on the image forming layer has been adopted, but there is a disadvantage that the sensitivity is lowered. In particular, in the case of a thermal transfer sheet that is exposed using a laser, a precise printed image is required, and there is a problem that dirt adhering to the roll surface moves to the image portion, and if the image is soiled, the commercial value is greatly reduced. .

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a thermal transfer sheet capable of forming a good image by eliminating roll contamination when transporting the thermal transfer sheet, and an image forming material using the same.

[0009]

As a result of intensive studies, the present inventors have found that the coefficient of static friction of the outermost layer on the side where the image forming layer of the thermal transfer sheet is coated is adjusted to a predetermined range. , Eliminates roll contamination when conveying the thermal transfer sheet, and finds that the formed image can have high image quality,
The present invention has been completed. The means for solving the above problems are as follows. <1> At least one light-to-heat conversion layer on a support,
A thermal transfer sheet having at least one image forming layer, wherein the outermost layer on the side on which the image forming layer is coated has a coefficient of static friction of 0.35 or less. <2> The coefficient of static friction is 0.20 or less.
1> The thermal transfer sheet according to <1>. <3> The thermal transfer sheet according to <1> or <2>, wherein the outermost layer is an image forming layer. <4> The thermal transfer sheet according to any one of <1> to <3>, wherein the light-to-heat conversion layer contains an infrared absorbing dye. <5> The outermost layer comprises a fatty acid having 9 to 27 carbon atoms and O
The thermal transfer sheet according to any one of <1> to <4>, further comprising a monoester with an alcohol having 2 to 5 H groups. <6> An image is formed by imagewise exposing using a laser having a wavelength of 750 nm or more.
> To <5>. <7> A support having voids, an image receiving sheet having thereon a cushion layer and an image receiving layer, and
6> An image forming material comprising the thermal transfer sheet according to any one of <1> to <6>.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the thermal transfer sheet of the present invention will be described in detail. FIG. 1 shows one embodiment of the thermal transfer sheet of the present invention. The thermal transfer sheet 10 includes a support 12 and
On top of that, the light-to-heat conversion layer 14, and further thereon, the image forming layer 16 is arranged, but the thermal transfer sheet of the present invention is not limited to this structure, the light-to-heat conversion layer and the image forming layer, Each support may have two or more layers. The light-to-heat conversion layer 14 contains a resin and a light-to-heat conversion substance that converts irradiated light energy into heat energy.
The image forming layer 16 contains at least a pigment that is transferred to an image receiving sheet to form an image. Thermal transfer sheet 1
The static friction coefficient of the outermost layer on the side where the 0 image forming layer 16 is coated is 0.35 or less. When the coefficient of static friction of the outermost layer exceeds 0.35, the roll is soiled at the time of manufacture or during use by a user, and causes deterioration of an image. In the thermal transfer sheet 10 of the present invention, since the coefficient of static friction of the outermost layer is within the above range, it is possible to eliminate roll contamination when transporting the thermal transfer sheet and to improve the quality of the formed image. More preferably, the static friction coefficient of the outermost layer is 0.20 or less.

In the present specification, the coefficient of static friction of the outermost layer means a value measured by the following method. A sample of the thermal transfer sheet (5 cm × 20 cm) is adhered on a gantry. Adhesion is carried out using an adhesive tape (for example, polyester adhesive tape, No. 31B75 high, manufactured by Nitto Denko Corporation) with the support of the thermal transfer sheet on the pedestal side (image forming layer facing upward). On the outermost layer on the side where the image forming layer is coated, a stainless steel terminal (35 m
mx75mm, 2.5mmr curved surface, 200g) and slowly tilt the gantry. The inclination angle θ of the gantry when the stainless steel terminal starts to slide is measured, and tan θ is defined as a coefficient of static friction. In FIG. 1, although the light-to-heat conversion layer and the image forming layer are in contact with each other,
A configuration in which a heat-sensitive release layer described later is provided on the light-to-heat conversion layer may be employed.

The coefficient of static friction of the outermost layer on the side on which the image forming layer is coated can be adjusted to the above range by, for example, including a slipping agent for lowering the coefficient of static friction in the outermost layer. The outermost layer is preferably an image forming layer in that the sensitivity is increased.

In particular, liquid paraffin, denatured or undenatured silicone oil, a monoester of a fatty acid having 9 to 27 carbon atoms and an alcohol having 2 to 5 OH groups, and (C _n H _2n O) A method of adding a compound having a structure (where n represents an integer of 1 to 5), a method of adding a slipping agent such as a surfactant, or a method of adding fine particles such as graphite, ethylene tetrafluoride, and molybdenum disulfide. This method is preferable because the coefficient of static friction of the outermost layer can be easily adjusted to the above range.

The liquid paraffin is-(CH ₂ C)
H ₂ ) _n- (where n represents an integer of 3 to 10). _{Specifically, - (CH 2 CH 2)} 4 -,
_{- (CH 2 CH 2) 5} -, - (CH 2 CH 2) 7 -, - (CH
₂ CH ₂ ) ₈ -,-(CH ₂ CH ₂ ) _10- and the like can be suitably used.

The modified silicone oil is a resin in which a side chain and / or a terminal (including both one terminal and both terminals) of a polysiloxane skeleton is substituted with a functional group. Specifically, (CH ₂ CH ₂ O) _n C _X H _{2X + 1} , (CH ₂ CH ₂ O)
_n (CH ₂ CH ₂ CH ₂ O) _m C _X H _{2X + 1} (where n is 1 to 2
Integer of 0, m represents an integer of 1 to 20, and x represents an integer of 0 to 5. ) And the like in the side chain and / or terminal can be suitably used. Further, as the unmodified silicone oil, specifically, polydimethylsiloxane is preferable, for example, a compound S shown below.
-1 or the like can be suitably used.

In the present invention, the use of a monoester of the above-mentioned fatty acid having 9 to 27 carbon atoms and an alcohol having 2 to 5 OH groups as a slipping agent can particularly reduce the static friction coefficient, This is preferable in that roll contamination when the sheet is conveyed can be eliminated and a good image can be formed. Further, the fatty acid constituting the monoester is more preferably one having 11 to 21 carbon atoms. Further, the alcohol constituting the monoester preferably has 2 to 3 OH groups, and glycerin is particularly preferable. When the fatty acid has less than 9 carbon atoms, it may be insufficient to lower the static friction coefficient. On the other hand, when the number of carbon atoms exceeds 27, the solubility in the coating solution is reduced, and the surface of the thermal transfer sheet has The smoothness may be poor. Specifically, for example, the following compounds S-5 and S-6 can be suitably used.

The compound having a (C _n H _2n O) structure in the molecule (where n represents an integer of 1 to 5) is preferably (C _n H _2n O) _m (where , M represents an integer of 1 to 20). Specifically, (C ₂ H ₄ O) _m , (C ₃ H ₆ O) _m (where m is 1 to
Represents an integer of 20. ).

Examples of the surfactant include anionic, cationic and nonionic surfactants. Specifically, anionic surfactants having a structure such as -SO ₃ Na, -SO ₃ K, etc. For example, the following compounds S-7 and S-
8 or the like can be suitably used.

In the following, among the slip agents used in the present invention, one example of a slip agent particularly preferably used is shown.

[0020]

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The content of the above-mentioned slip agent or fine particles in the outermost layer can be appropriately selected depending on the kind of the material to be used, but is preferably 6 to 30 mg / m ^{2, and} more preferably 10 to 20 mg / m ^2.
mg / m ² is more preferred. If the content is less than 6 mg / m ² , the desired coefficient of static friction cannot be obtained, and the effects of the present invention may not be achieved. On the other hand, the content is 30 mg
/ M ² , not only does the static friction coefficient not decrease any more, but also the surface stickiness and adhesion resistance may deteriorate. However, depending on the type of the slip agent or the fine particles to be used, a desired static friction coefficient can be obtained even when the content in the outermost layer is 1 to 5 mg / m ² .

In the present invention, in order to adjust the static friction coefficient of the outermost layer to 0.35 or less, the following coating method and drying method are performed using the outermost layer forming solution containing the above-mentioned slip agent or fine particles. This can be suitably achieved. As the solvent used for preparing the outermost layer forming solution, toluene, MEK, ethanol, n-propanol, i-propanol, MIBK and the like can be used. As a method of applying the outermost layer forming solution,
A spin coating method, a doctor blade coating method, a Meyer bar coating method and the like are preferably used. To dry the outermost layer forming solution, 25 to 150 ° C., preferably 40 to 150 ° C.
A method using 110 ° C. warm air is preferred. The drying air is 0.
It is about 2 to 15 m / min, preferably 0.5 to 5 m / min. The drying time is about 10 seconds to 10 minutes.
0 seconds to 5 minutes is preferred.

Hereinafter, the support, the light-to-heat conversion layer, and the image forming layer, which constitute the thermal transfer sheet of the present invention, and other optional layers will be described in detail. [Support] The material of the support of the thermal transfer sheet is not particularly limited, and various support materials can be used according to the purpose. Preferred examples of the support material include synthetic resin materials such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and styrene-acrylonitrile copolymer. . Among them, biaxially stretched polyethylene terephthalate is preferable in consideration of mechanical strength and dimensional stability against heat. When the thermal transfer sheet of the present invention is used for producing a color proof using laser recording, the support of the thermal transfer sheet is preferably formed of a transparent synthetic resin material that transmits laser light.

The support of the thermal transfer sheet may be subjected to a surface activation treatment and / or the provision of one or more undercoat layers in order to improve the adhesion to the light-to-heat conversion layer provided thereon. Is preferred. Examples of the surface activation treatment include a glow discharge treatment and a corona discharge treatment.

[Light-to-heat conversion layer] The light-to-heat conversion layer contains a light-to-heat conversion material and a resin, and further contains other components as required.

(Light-to-heat conversion substance) The light-to-heat conversion substance is a substance having a function of converting irradiated light energy into heat energy. Generally, it is a dye capable of absorbing laser light (including a pigment; the same applies hereinafter). The thermal transfer sheet of the present invention is preferably such that an image is formed by imagewise exposing using a laser having a wavelength of 750 nm or more in that the material can be handled under a white lamp having a wavelength of about 400 to 600 nm. It is preferable to use a dye capable of absorbing such laser light.

When recording an image with an infrared laser, it is preferable to use an infrared absorbing dye as the photothermal conversion material. Examples of such dyes include black pigments such as carbon black, pigments of macrocyclic compounds having absorption in the visible to near infrared region such as phthalocyanine and naphthalocyanine, and laser absorbing materials for high-density laser recording such as optical disks. (Cyanine dyes such as indolenine dyes, anthraquinone dyes, azulene dyes, and phthalocyanine dyes), and organic metal compound dyes such as dithiol nickel complexes. Above all, infrared-absorbing dyes such as cyanine-based dyes show a large extinction coefficient for light in the infrared region, so when used as a light-to-heat conversion material, the light-to-heat conversion layer can be made thinner, and recording of a heat transfer sheet can be performed. This is preferable because the sensitivity can be further improved. Further, as the light-to-heat conversion material, a particulate inorganic material such as blackened silver can be used in addition to the pigment.

The preferred content of the light-to-heat conversion material in the light-to-heat conversion layer varies depending on the material used, but the light used for image recording (700 when using an infrared laser).
It is preferable that the light-to-heat conversion layer is contained so as to have a transmission optical density of 0.1 to 2.0 with respect to light having a wavelength in the range of 〜2000 nm). Is more preferred. If the optical density is less than 0.1, the sensitivity of the thermal transfer sheet may be low, and
If it is higher than 0, the production cost increases.

(Resin) The resin contained in the photothermal conversion layer is
It has at least the strength to form a layer on the support. Furthermore, at the time of image recording, while having a high thermal conductivity,
It is preferable that the resin is heat-resistant and does not decompose even by heat generated from the light-to-heat conversion material. Specifically, 20
It has a glass transition temperature of 0 ° C. or more and 400 ° C. or less, and a thermal decomposition temperature (TGA method at a rate of 10 ° C./min,
A resin having a temperature of 5% weight loss in an air stream) of 450 ° C. or more is preferred. More preferably, 250 ° C. or higher and 350
It is a resin having a glass transition temperature of 475C or lower and a thermal decomposition temperature of 475C or higher. Glass transition temperature is 200
If the temperature is lower than 0 ° C., fogging may occur in the formed image, and if the temperature is higher than 400 ° C., the solubility of the resin decreases,
Production efficiency may decrease. In addition, the thermal decomposition temperature is 4
If the temperature is lower than 50 ° C., fog and image quality (resolution) may be similarly reduced.

Specifically, acrylic resins such as polymethyl methacrylate, polycarbonate, polystyrene,
Vinyl chloride / vinyl acetate copolymer, vinyl resin such as polyvinyl alcohol, polyvinyl butyral, polyester, polyvinyl chloride, polyamide, polyimide, polyetherimide, polysulfone, polyethersulfone, aramid, polyurethane, epoxy resin, urea / melamine Resins. Among these, a polyimide resin is preferable.

Particularly, the polyimide resins represented by the following general formulas (I) to (VII) are soluble in an organic solvent, and the use of these polyimide resins is preferable because the productivity of the thermal transfer sheet is improved. It is also preferable in that the viscosity stability, long-term storage property, and moisture resistance of the light-to-heat conversion layer coating solution are improved.

[0032]

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In the above general formulas (I) and (II), Ar
¹ represents an aromatic group represented by the following structural formulas (1) to (3), and n represents an integer of 10 to 100.

[0034]

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[0035]

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In the above general formulas (III) and (IV), Ar ²
Represents an aromatic group represented by the following structural formulas (4) to (7), and n represents an integer of 10 to 100.

[0037]

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[0038]

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In the above general formulas (V) to (VII), n and m
Represents an integer of 10 to 100, respectively. In the formula (VI), the ratio of n: m is 6: 4 to 9: 1.

Incidentally, as a guide for judging whether or not the resin is soluble in an organic solvent, it is based on that at 25 ° C., at least 10 parts by weight of the resin is dissolved with respect to 100 parts by weight of N-methylpyrrolidone. When it is dissolved in 10 parts by weight or more, it is preferably used as a resin for the light-to-heat conversion layer. More preferably, the resin dissolves in 100 parts by weight or more based on 100 parts by weight of N-methylpyrrolidone.

(Formation of Light-to-Heat Conversion Layer) The light-to-heat conversion layer is prepared by preparing a coating solution in which a light-to-heat conversion substance and a binder resin are dissolved.
This can be provided by applying this on a support and drying it. Examples of the organic solvent for dissolving the polyimide resin include, for example, n-hexane, cyclohexane, diglyme, xylene, toluene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone, acetone, cyclohexanone, 1,4-dioxane, 1,3-dioxolan, dimethyl Examples include acetate, N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, dimethylacetamide, γ-butyrolactone, ethanol, methanol and the like. Coating and drying can be performed by using ordinary coating and drying methods. Drying is usually performed at a temperature of 300 ° C. or less, preferably at a temperature of 200 ° C. or less. When polyethylene terephthalate is used as the support, drying is preferably performed at a temperature of 80 to 150 ° C.

The weight ratio of the solid content of the light-to-heat conversion substance to the resin in the light-to-heat conversion layer is preferably from 1:20 to 2: 1, and more preferably from 1:10 to 2: 1. If the amount of the resin is too small, the cohesive force of the light-to-heat conversion layer decreases, and when the formed image is transferred to the image receiving sheet, the light-to-heat conversion layer is easily transferred together, causing color mixing of the image. On the other hand, if the amount of the resin is too large, the thickness of the light-to-heat conversion layer becomes large in order to achieve a constant light absorptivity, and the sensitivity tends to be reduced. The layer thickness of the light-to-heat conversion layer is preferably from 0.05 to 2.0 μm, more preferably from 0.1 to 0.3 μm.

[Image Forming Layer] The image forming layer contains at least a pigment for forming an image by being transferred to an image receiving sheet, and further contains a binder resin for forming a layer and, if desired, other components. contains. When the outermost layer is an image forming layer, the image forming layer may contain the slip agent or fine particles for adjusting the coefficient of static friction.

(Pigments) Pigments are generally classified into organic pigments and inorganic pigments. The former has properties such as excellent transparency of a coating film, and the latter generally has properties such as excellent concealing properties. May be appropriately selected according to the conditions. When the thermal transfer sheet of the present invention is used for printing color proofing, an organic pigment that matches or has a similar color tone to yellow, magenta, cyan, and black generally used for printing inks is preferably used. In addition, a metal powder, a fluorescent pigment, or the like may be used. Examples of preferably used pigments include:
Examples include azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, and nitro pigments. The pigments used in the image forming layer are separated by hue,
These are listed below, but are not limited thereto.

1) Yellow pigment Hansa Yellow G, Hansa Yellow 5G, Hansa Yellow 10G, Hansa Yellow A, Pigment Yellow L,
Permanent Yellow NCG, Permanent Yellow F
GL, permanent yellow HR. 2) red pigment permanent red 4R, permanent red F2R,
Permanent Red FRL, Lake Red C, Lake Red D, Pigment Scarlet 3B, Bordeaux 5B,
Alizarin Lake, Rhodamine Lake B. 3) Blue pigments Phthalocyanine blue, Victoria blue lake, Fast sky blue. 4) Black pigment carbon black. The image forming layer preferably contains 30 to 70% by weight of the pigment, more preferably 40 to 60% by weight.

(Binder Resin) As the binder resin for the image forming layer, an amorphous organic high molecular polymer having a softening point of 40 ° C. to 150 ° C. is preferable. As the amorphous organic high-molecular polymer, for example, butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, styrene, vinyltoluene, α-methylstyrene, 2-methylstyrene, Chlorstyrene, vinylbenzoic acid, vinylbenzenesulfonic acid sodium, styrene such as aminostyrene and derivatives thereof, homopolymers and copolymers of substituted products, methyl methacrylate, ethyl methacrylate, butyl methacrylate,
Methacrylic acid esters such as hydroxyethyl methacrylate and acrylic acid esters such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, α-ethylhexyl acrylate and dienes such as acrylic acid, butadiene, isoprene, acrylonitrile, vinyl ethers, and maleic acid And maleic esters, maleic anhydride, cinnamic acid, vinyl chloride,
A vinyl monomer such as vinyl acetate alone or a copolymer with another monomer can be used. These resins can be used as a mixture of two or more kinds. The image forming layer preferably contains 30 to 70% by weight of resin, more preferably 40 to 60% by weight.

(Other Components) -Plasticizer- Using the thermal transfer sheet of the present invention, a multicolor image is formed by repeatedly superimposing a number of image layers (image forming layers on which images are formed) on the same image receiving sheet. In the case of manufacturing, the image forming layer preferably contains a plasticizer in order to enhance the adhesion between images. Examples of such plasticizers include dibutyl phthalate, di-n-octyl phthalate, di (2-ethylhexyl phthalate, dinonyl phthalate, dilauryl phthalate,
Phthalates such as butyl lauryl phthalate and butyl benzyl phthalate; dibasic aliphatic esters such as di (2-ethylhexyl) adipate and di (2-ethylhexyl) sebacate; tricresyl phosphate; Examples thereof include phosphoric acid triesters such as 2-ethylhexyl), polyol polyesters such as polyethylene glycol ester, and epoxy compounds such as epoxy fatty acid ester.

In the image forming layer, the weight ratio of the plasticizer to the total amount of the pigment and the resin is generally
100: 1 to 100: 3, preferably 100: 1.5 to
Used to be 100: 2. In the image forming layer,
Further, a surfactant, a thickener and the like are added as required.

-Thermal Sensitive Material- The image forming layer may contain a thermosensitive material which is a material which generates gas by the action of heat or releases water or the like. When a heat-sensitive material is contained in the image forming layer, the bonding strength between the light-to-heat conversion layer and the image forming layer can be reduced by the action of heat generated from the light irradiation part of the light-to-heat conversion layer, and the image forming layer is transferred. It is preferable because the property is further improved. Examples of such a heat-sensitive material include a compound (polymer or low-molecular compound) that decomposes or degrades by heat to generate a gas, and / or a compound that absorbs or adsorbs a considerable amount of easily vaporizable gas such as moisture. (A polymer or a low molecular compound) or the like can be used. Examples of polymers that decompose or degrade by heat to generate gas include self-oxidizing polymers such as nitrocellulose, chlorinated polyolefin, chlorinated rubber, polyvinyl chloride, polyvinyl chloride,
Halogen-containing polymers such as polyvinylidene chloride, acrylic polymers such as polyisobutyl methacrylate in which volatile compounds such as water are adsorbed, and cellulose esters such as ethyl cellulose in which volatile compounds such as water are adsorbed, such as water. Natural polymer compounds such as gelatin to which volatile compounds have been adsorbed can be mentioned.
Examples of the low molecular weight compound which decomposes or degrades by heat to generate a gas include a compound which generates a gas upon exothermic decomposition such as a diazo compound or azide. It is preferable that the heat-sensitive material is decomposed or deteriorated by heat at 280 ° C. or lower, as described above, and particularly at 23 ° C.
It preferably occurs at 0 ° C. or lower.

(Formation of Image Forming Layer) For the image forming layer, a coating solution prepared by dissolving or dispersing a pigment and the binder resin or the like is prepared, and this is coated on a light-to-heat conversion layer (the following heat-sensitive release layer is formed on the light-to-heat conversion layer). When it is provided, it can be provided by coating on the layer) and drying. Examples of the solvent used for preparing the coating liquid include n-propyl alcohol, methyl ethyl ketone, propylene glycol monomethyl ether (MFG), and methanol. Coating and drying can be performed using ordinary coating and drying methods, but when the coating liquid contains the above-mentioned slip agent or fine particles for adjusting the coefficient of static friction, use the above-described coating and drying method. It is preferable to form a layer by carrying out. The thickness (dry layer thickness) of the image forming layer is preferably from 0.1 to 1.5 μm,
0.3 to 1.0 μm is more preferable. The layer thickness is 0.1μ
When the thickness is less than m, the image density may be insufficient, while when the thickness is more than 1.5 μm, the image quality may be deteriorated.

[Other Layers] (Thermal Release Layer) In the thermal transfer sheet of the present invention, a thermal release layer containing the above-mentioned thermal material may be provided between the light-to-heat conversion layer and the image forming layer. When the low-molecular compound is used as the heat-sensitive material to be contained in the heat-sensitive release layer, it is desirable to combine the low-molecular compound with a binder resin. As the binder resin, the polymer exemplified as the heat-sensitive material, which itself decomposes or degrades by heat to generate a gas, may be used, but a normal binder resin having no such property may be used. it can. When a heat-sensitive low-molecular compound and a binder resin are used in combination, the weight ratio of the former to the latter is preferably 0.02: 1 to 3: 1, and 0.02: 1 to 3: 1.
More preferably, the ratio is 5: 1 to 2: 1. The heat-sensitive release layer desirably covers the light-to-heat conversion layer over substantially the entire surface, and the thickness thereof is generally 0.03 to 1 μm.
And preferably in the range of 0.05 to 0.5 μm. When the heat-sensitive release layer is provided, it is preferable that the material has a barrier property with respect to the material of the image forming layer so that the interlayer adhesion does not change.

On a support, a light-to-heat conversion layer, a heat-sensitive release layer,
In the case of a thermal transfer sheet having a configuration in which the image forming layers are laminated in this order, the heat-sensitive release layer decomposes and degrades by the heat transmitted from the light-to-heat conversion layer to generate gas. Then, due to the decomposition or generation of gas, the heat-sensitive peeling layer partially disappears, or cohesive failure occurs in the heat-sensitive peeling layer, and the bonding force between the light-heat conversion layer and the image forming layer decreases. For this reason, depending on the behavior of the heat-sensitive release layer, a part of the heat-sensitive release layer may adhere to the image forming layer and appear on the surface of a finally formed image, which may cause color mixing of the image. Therefore, even when such transfer of the heat-sensitive release layer occurs, the heat-sensitive release layer is hardly colored, that is, high in visible light, so that no visual color mixture appears in the formed image. It is desirable to show permeability. Specifically, the light absorption of the heat-sensitive peeling layer is 50% or less, preferably 1 to visible light.
0% or less.

(Undercoat layer) It is preferable to provide one or more undercoat layers on the support of the thermal transfer sheet in order to improve the adhesion to the light-to-heat conversion layer provided thereon. . As a material of the undercoat layer, it shows high adhesiveness to both surfaces of the support and the light-to-heat conversion layer, and has a low thermal conductivity,
Further, it is preferable that the material has excellent heat resistance. Examples of such undercoat layer materials include styrene, styrene-
Butadiene copolymer, gelatin and the like can be mentioned. The thickness of the entire undercoat layer is usually 0.01 to 2 μm.
Further, on the surface of the thermal transfer sheet opposite to the side on which the light-to-heat conversion layer is provided, various functional layers such as an anti-reflection layer can be provided or surface treatment can be performed, if necessary.

The thermal transfer sheet of the present invention is combined with the following image receiving sheet. [Image-Receiving Sheet] The image-receiving sheet is usually provided with a support and one or more image-receiving layers provided thereon. If desired, any of a cushion layer, a release layer, and an intermediate layer may be provided between the support and the image-receiving layer. Or one or two or more layers. Further, when a back layer is provided on the surface of the support opposite to the image receiving layer,
It is preferable in terms of transportability.

(Support) Examples of the support include ordinary sheet-like base materials such as plastic sheets, metal sheets, glass sheets, and paper. Examples of plastic sheets include polyethylene terephthalate sheet,
Examples include a polycarbonate sheet, a polyethylene sheet, a polyvinyl chloride sheet, a polyvinylidene chloride sheet, a polystyrene sheet, a styrene-acrylonitrile sheet, and a polyester sheet. As the paper, printing paper, coated paper, or the like can be used.

It is preferable that the support has minute voids (voids) because curling can be prevented and image quality can be improved. Such a support is, for example, a thermoplastic resin, a mixed melt obtained by mixing an inorganic pigment or a filler made of an incompatible polymer with the thermoplastic resin, a single-layer or multi-layer by a melt extruder. It can be produced by forming a film and further stretching it uniaxially or biaxially. In this case, the porosity is determined by the selection of the resin and the filler, the mixing ratio, the stretching conditions, and the like.

As the thermoplastic resin, a polyolefin resin such as polypropylene and a polyethylene terephthalate resin are preferable because of good crystallinity, good stretchability, and easy void formation. It is preferable to use the above-mentioned polyolefin resin or polyethylene terephthalate resin as a main component, and appropriately use a small amount of another thermoplastic resin in combination. As the inorganic pigment used as the filler, those having an average particle size of 1 μm or more and 20 μm or less are preferable, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica and the like can be used. When polypropylene is used as the thermoplastic resin as the incompatible polymer used as the filler, it is preferable to combine polyethylene terephthalate as the filler. The content of the filler such as an inorganic pigment in the support is generally about 2 to 30% by volume.

The thickness of the support of the image receiving sheet is usually from 10 to
It is 400 μm, preferably 25 to 200 μm. Further, the surface of the support is subjected to a surface treatment such as a corona discharge treatment or a glow discharge treatment in order to enhance the adhesion with the image receiving layer (or the cushion layer) or the adhesion with the image forming layer of the thermal transfer sheet. May be.

(Image-Receiving Layer) It is preferable to provide one or more image-receiving layers on a support in order to transfer and fix the image-forming layer on the surface of the image-receiving sheet. The image receiving layer is preferably a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, for example, acrylic acid, methacrylic acid,
Acrylic esters, homopolymers and copolymers of acrylic monomers such as methacrylic esters, methyl cellulose, ethyl cellulose, cellulose polymers such as cellulose acetate, polystyrene, polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, etc. And homopolymers and copolymers of vinyl monomers, condensation polymers such as polyesters and polyamides, and rubber polymers such as butadiene-styrene copolymers.
The binder of the image receiving layer is preferably a polymer having a glass transition temperature (Tg) lower than 90 ° C. in order to obtain a proper adhesive strength with the image forming layer. For this purpose, it is also possible to add a plasticizer to the image receiving layer. Further, the binder polymer preferably has a Tg of 30 ° C. or higher in order to prevent blocking between sheets. As the binder polymer of the image receiving layer, the same as the binder polymer of the image forming layer, in that the adhesiveness with the image forming layer during laser recording is improved, and the sensitivity and the image strength are improved.
Or it is particularly preferable to use a similar polymer.

In the case where an image is once formed on the image receiving layer and then re-transferred to a printing paper or the like, at least one of the image receiving layers is preferably formed from a photocurable material. Examples of the composition of such a photocurable material include: a) a photopolymerizable monomer comprising at least one of a polyfunctional vinyl or vinylidene compound capable of forming a photopolymer by addition polymerization;
Examples of the combination include b) an organic polymer, c) a photopolymerization initiator, and, if necessary, additives such as a thermal polymerization inhibitor. As the polyfunctional vinyl monomer, unsaturated esters of polyols, particularly esters of acrylic acid or methacrylic acid (eg, ethylene glycol diacrylate, pentaerythritol tetraacrylate) are used.

Examples of the organic polymer include the above-mentioned polymer for forming an image receiving layer. As the photopolymerization initiator, a general photoradical polymerization initiator such as benzophenone and Michler's ketone is used in a ratio of 0.1 to 20% by weight in the layer.

The thickness of the image receiving layer is 0.3 to 7 μm, preferably 0.7 to 4 μm. When it is less than 0.3 μm, the film strength is insufficient at the time of retransfer to the printing paper, and the film is easily broken. If it is too thick, the gloss of the image after retransfer of the paper increases, and the closeness to the printed matter decreases.

(Cushion Layer) A cushion layer may be provided between the support and the image receiving layer. When the cushion layer is provided, the adhesion between the image forming layer and the image receiving layer can be improved at the time of laser thermal transfer, and the image quality can be improved. Further, at the time of recording, even if foreign matter is mixed between the thermal transfer sheet and the image receiving sheet, the gap between the image receiving layer and the image forming layer becomes small due to the deforming action of the cushion layer, and as a result, the image defect size such as white spots is reduced. Can also be reduced. Furthermore, when an image is transferred and formed and then transferred to a separately prepared printing paper or the like, the image receiving surface is deformed according to the uneven surface of the paper, so that the transferability of the image receiving layer can be improved, and By reducing the gloss of the object, the similarity with the printed matter can be improved.

The cushion layer is configured to be easily deformed when a stress is applied to the image receiving layer. To achieve the above effect, a material having a low elastic modulus, a material having rubber elasticity, or easily softened by heating. It is preferred to be made of a thermoplastic resin. The elastic modulus of the cushion layer at room temperature is 9.8 × 10 ^{5 to} 4.9 × 10 ⁷ Pa, particularly 2.9 × 10 ⁷ Pa.
^The pressure is preferably ^{6 to} 1.5 × 10 ⁷ Pa. In addition, JIS K2530 is required to squeeze foreign substances such as rubber.
The penetration (25 ° C, 100g, 5 seconds) determined by
It is preferable that it is above. The glass transition temperature of the cushion layer is 80 ° C. or lower, preferably 25 ° C. or lower. It is also possible to suitably add a plasticizer to the polymer binder in order to adjust these physical properties, for example, Tg.

Specific materials used as the binder of the cushion layer include rubbers such as urethane rubber, butadiene rubber, nitrile rubber, acrylic rubber, and natural rubber, as well as polyethylene, polypropylene, polyester, and styrene-butadiene copolymer. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, vinyl chloride resin containing a plasticizer, polyamide resin, phenol resin and the like. Although the thickness of the cushion layer varies depending on the resin used and other conditions, it is usually 3 to 100 μm,
Preferably it is 10 to 52 μm.

The image receiving layer and the cushion layer need to be adhered to each other up to the stage of laser recording, but are preferably provided so as to be peelable in order to transfer the image to the printing paper. In order to facilitate peeling, it is preferable to provide a peeling layer having a thickness of about 0.1 to 2 μm between the cushion layer and the image receiving layer. This release layer preferably has a function as a barrier for a coating solvent at the time of coating the image receiving layer.

The image receiving sheet combined with the thermal transfer sheet of the present invention may have a structure in which the image receiving layer also serves as a cushion layer. In this case, the image receiving sheet may be a support / cushionable image receiving layer or a support / cushion layer. It may have a configuration of an undercoat layer / cushionable image receiving layer. Also in this case, it is preferable that the cushioning image-receiving layer is provided so as to be releasable so that it can be re-transferred to the printing paper. In this case, the image after retransfer to the printing paper becomes an image having excellent gloss. The thickness of the cushioning image-receiving layer is 5 to 100 μm, preferably 10 to 40 μm.

(Other Layers) In the image receiving sheet, it is preferable to provide a back layer on the surface of the support opposite to the surface on which the image receiving layer is provided, since the transportability of the image receiving sheet is improved. . It is preferable to add an antistatic agent such as a surfactant and tin oxide fine particles and a matting agent such as silicon oxide and PMMA particles to the back layer in terms of improving transportability in a recording apparatus. The additive is not limited to the back layer,
If necessary, it can be added to the image receiving layer and other layers. The type of the additive cannot be specified unconditionally depending on the purpose, but for example, in the case of a matting agent, the average particle size is 0.1 mm.
Particles of 5 to 10 μm can be added in the layer in an amount of about 0.5 to 80% by weight. Various surfactants may be used as the antistatic agent so that the surface resistance of the layer is 10 ¹² Ω or less, more preferably 10 ⁹ Ω or less at 23 ° C. and 50% RH.
It can be appropriately selected from conductive agents and used.

[Image Forming Material] The image forming material of the present invention is a laminate comprising the thermal transfer sheet and the image receiving sheet. The laminate of the thermal transfer sheet and the image receiving sheet can be formed by various methods. For example, it can be easily obtained by stacking the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet and passing them through a pressure and heating roller. The heating temperature in this case is 160 ° C. or less, especially 1
30 ° C. or lower is preferred.

As another method for obtaining a laminate, a vacuum contact method is also suitably used. In the vacuum contact method, first, an image receiving sheet is wound on a drum provided with a suction hole for evacuation, and then a thermal transfer sheet slightly larger than the image receiving sheet is pressed while uniformly extruding air with a squeeze roller. This is a method of vacuum contact. As another method, there is a method in which an image receiving sheet is mechanically attached to a metal drum while being pulled, and a thermal transfer sheet is further applied and adhered to the metal drum while being mechanically pulled. Among these methods, the vacuum adhesion method is particularly preferable because temperature control of a heat roller or the like is not required and lamination can be performed quickly and uniformly.

[Image Forming Method] An image forming method using the image forming material of the present invention will be schematically described with reference to FIG.
Note that the same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. An image forming laminate 30 in which the image receiving sheet 20 is laminated on the surface of the image forming layer 16 of the thermal transfer sheet 10 is prepared. The image receiving sheet 20 has a support 22 and a cushion layer 24 and an image receiving layer 26 on the support 22, and the surface of the image forming layer 16 of the thermal transfer sheet 10 includes
The image receiving layer 26 is laminated so as to be in contact with the image receiving layer 26 (FIG. 2).
(A)). From the support side of the laminate 30, the laser beam 4
0 is illuminated in a time series like an image,
In the light-heat conversion layer 14, the area irradiated with the laser light generates heat, and the adhesion to the image forming layer 16 is reduced (FIG. 2B). Thereafter, when the image receiving sheet 20 and the thermal transfer sheet 10 are peeled off, the laser beam irradiated area 16 'of the image forming layer 16 is transferred onto the image receiving layer 26 of the image receiving sheet 20 (FIG. 2).
(C)).

The joining of the thermal transfer sheet 10 and the image receiving sheet 20 may be performed immediately before the laser beam irradiation operation. In this laser beam irradiation operation, usually, the image receiving sheet side of the image forming laminate is evacuated to the surface of a recording drum (a rotating drum having a vacuum forming mechanism inside and a number of minute openings on the surface). In this state, laser light is irradiated from the outside, that is, from the thermal transfer sheet side. The laser beam is scanned so as to reciprocate in the width direction of the drum, and the drum is rotated at a constant angular velocity during the irradiation operation.

As the laser light 40 used for light irradiation, gas laser light such as argon ion laser light, helium neon laser light, helium cadmium laser light,
Direct laser light such as solid-state laser light such as AG laser light, semiconductor laser light, dye laser light, and excimer laser light is used. Alternatively, light or the like obtained by converting these laser lights to half the wavelength through a second harmonic element can be used. In the image forming method using the thermal transfer sheet of the present invention, it is preferable to use a semiconductor laser in consideration of output power, ease of modulation, and the like. In the image forming method using the thermal transfer sheet of the present invention, the laser beam has a beam diameter of 5 to 50 μm (particularly 6 μm) on the light-to-heat conversion layer.
Irradiation is preferably carried out under such conditions that the range is about 30 μm), and the scanning speed is preferably 1 m / sec or more (particularly 3 m / sec or more).

The image forming method includes the steps of manufacturing a black mask,
Alternatively, it can be used for forming a single-color image, but can also be advantageously used for forming a multi-color image.
As a method for forming a multicolor image, for example, a method through the following steps can be mentioned. For example, a thermal transfer sheet having an image forming layer containing colorants having mutually different hues is prepared, and three types (three colors, for example, cyan, magenta, and magenta) of an image forming laminate obtained by combining this with an image receiving sheet are prepared. , Yellow) or four types (four colors, for example, cyan,
Magenta, yellow, black). To each of the laminates, for example, through a color separation filter, irradiate a laser beam according to a digital signal based on the image, subsequently, peel off the thermal transfer sheet and the image receiving sheet, each image receiving sheet color separation image of each color Are formed independently. Next, a multi-color image can be formed by sequentially laminating each of the formed color separation images on an actual support such as a separately prepared printing paper or a similar support.

[0075]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In the following description, “parts” means “parts by weight” unless otherwise specified. (Example 1) -Preparation of thermal transfer sheet- 1) Preparation of coating solution for light-to-heat conversion layer The following components were mixed with stirring with a stirrer to prepare a coating solution for a light-to-heat conversion layer. [Coating liquid composition for light-to-heat conversion layer]-Light-to-heat conversion material 10 parts (infrared absorbing dye: "NK-2014", manufactured by Nippon Kogyo Dye Co., Ltd.)-Binder 200 parts (polyimide resin: "Licacoat SN-20", new Glass transition temperature: 295 ° C, thermal decomposition temperature: 510 ° C, manufactured by Nippon Rika Co., Ltd. ・ 2000 parts of N-methyl-2-pyrrolidone ・ 1 part of surfactant (“MegaFac F-177”, Dainippon Ink & Chemicals, Inc. Co., Ltd.)

2) Formation of a light-to-heat conversion layer on the surface of a support On one surface of a biaxially stretched polyethylene terephthalate film having a thickness of 75 μm as a support, the coating solution for a light-to-heat conversion layer was applied by a spin coater (Whyler). Then, the coated material was dried in an oven at 120 ° C. for 3 minutes to form a light-to-heat conversion layer on the support. The obtained light-to-heat conversion layer had an absorption maximum near a wavelength of 830 nm, and its absorbance (optical density: OD) was measured by a Macbeth densitometer to find OD = 1.05. When the cross section of the light-to-heat conversion layer was observed with a scanning electron microscope, the film thickness was 0.4 μm on average.

3) Preparation of Coating Solution for Image Forming Layer The following components were prepared using a paint shaker (Toyo Seiki Co., Ltd.)
) For 6 hours, then remove the glass beads,
A yellow pigment dispersion mother liquor was prepared. [Pigment dispersion mother liquor composition]-24 parts of pigment (yellow pigment (CI Pigment Yellow 1)-12 parts of binder (polyvinyl butyral: "Denka butyral # 2000-L", manufactured by Denki Kagaku Kogyo KK, Vicat Softening) (Point 57 ° C) ・ Dispersing aid 0.8 part (“Solsperse S-20000”, manufactured by ICI Co., Ltd.) ・ n-propyl alcohol 110 parts ・ Glass beads (diameter 2 mm) 110 parts

Next, the following components were mixed while stirring with a stirrer to prepare a coating solution for a yellow image forming layer. [Coating solution composition for image forming layer] ・ 120 parts of the above-mentioned yellow pigment-dispersed mother liquor ・ 880 parts of n-propyl alcohol ・ 1 part of behenic acid ・ 0.8 parts of surfactant (“MegaFac F-177”, Dainippon Ink and Chemicals, Inc.)・ Sliding agent (compound represented by S-1) 2 parts

4) Formation of Image Forming Layer on Surface of Light-to-Heat Conversion Layer The above-mentioned coating solution for the image-forming layer was applied to the surface of the above-mentioned light-to-heat conversion layer for 1 minute using a wheeler.
After drying in an oven at 2 ° C. for 2 minutes, an image forming layer was formed on the light-to-heat conversion layer. The content (application amount) of the slip agent is 1
It was 0 mg / m ² . When the cross section of the image forming layer was observed by a scanning electron microscope,
μm. Through the above steps, a thermal transfer sheet in which a light-to-heat conversion layer and an image forming layer were provided in this order on a support was produced. The obtained yellow thermal transfer sheet is
When the absorbance (optical density: OD) was measured with a Macbeth densitometer, the OD was 0.7. After the thermal transfer sheet was stored for 10 days in an atmosphere of 25 ° C. and 60% RH, the following evaluation was performed.

<Evaluation of Coefficient of Static Friction> The coefficient of static friction was measured by the method described above. The measurement was performed in an environment of 25 ° C. and 60% RH, and the heat transfer sheet as a sample was conditioned for 2 hours before the measurement. Table 1 shows the results.

<Evaluation of Surface Contamination of Stainless Steel Terminal> The stainless steel terminal used for measuring the static friction coefficient was pressed against the surface of the thermal transfer sheet as a sample with a force of 3 kg, and 10 cm in diameter.
5 reciprocations over a distance of 20 cm at a speed of / sec. afterwards,
The stains on the stainless steel terminals were visually observed and evaluated as follows. That is, ◎ indicates that no dirt was observed, ○ indicates that dirt was hardly observed, △ indicates that dirt was slightly observed, X indicates that dirt was observed, and XX indicated that dirt was marked. did. Of these, ◎, ○, and 実 用 are practically acceptable. Table 1 shows the results.

Next, an image forming material composed of the thermal transfer sheet and the image receiving sheet was prepared by combining the above-mentioned thermal transfer sheet and the following image receiving sheet. -Preparation of Image Receiving Sheet- [Preparation of Cushion Layer Coating Solution] A cushion layer coating solution having the following composition was prepared. -Vinyl chloride-vinyl acetate copolymer 25 parts (MPR-TSL plasticizer manufactured by Nissin Chemical Co., Ltd.)-Hexafunctional acrylate monomer 12 parts ("DPCA-120", manufactured by Nippon Kayaku Co., Ltd., molecular weight) 1947)-Surfactant 0.4 part (Megafac F-177, manufactured by Dainippon Ink & Chemicals, Inc.)-Methyl ethyl ketone 75 parts

[Preparation of Coating Solution for Image Receiving Layer] A coating solution for image receiving layer having the following composition was prepared.・ Polyvinyl butyral 16 parts (“Denka Butyral # 2000-L”, manufactured by Denki Kagaku Kogyo KK)・ 200 parts of n-propyl alcohol

Using a narrow coater, a polyester film having voids (“Lumirror E-68L”, manufactured by Toray Industries, Inc.)
The above-mentioned coating solution for a cushion layer was applied thereon, the coating layer was dried, and then the coating solution for an image receiving layer was applied, and the coating layer was dried. The coating amount was adjusted so that the thickness of the cushion layer after drying was about 20 μm and the thickness of the image receiving layer was about 2 μm.

-Preparation of Laminate (Image Forming Material)-An image forming layer of the thermal transfer sheet and an image receiving layer of the image receiving sheet were overlapped to prepare a laminate.

<Evaluation of Image Quality> The laminated body was wound around a rotating drum provided with a suction hole for vacuum suction so that the support side of the image receiving sheet was in contact with the drum surface.
The laminate was fixed to the drum surface by applying a vacuum to the inside of the drum. The surface of the laminate on the drum was exposed from the outside with an outer drum type exposing machine equipped with a semiconductor laser having a wavelength of 808 nm, and a laser image was recorded on the laminate. This operation was repeated continuously for 100 sheets. The laser irradiation conditions are as follows. Laser power: 115 mW 1 / e ² Beam diameter: 20 μm Main scanning speed: 4 m / sec Sub-scanning pitch (sub-scanning amount per rotation): 20 μm

The stain on the obtained image was visually observed and evaluated as follows. That is, ◎ indicates that no dirt was observed, ○ indicates that dirt was hardly observed, △ indicates that dirt was slightly observed, X indicates that dirt was observed, and XX indicated that dirt was marked. did. Of these, ◎, ○, and 実 用 are practically acceptable. Table 1 shows the results.

(Examples 2 to 10, Comparative Examples 1 to 5) In Example 1, a slip agent shown in Table 1 (symbols represent the compounds exemplified above) was used for preparing the coating solution for the image forming layer. , Table 1
A thermal transfer sheet was prepared in the same manner as in Example 1 except that the amount was added so as to have the coating amount shown in Table 1, and the static friction coefficient and the surface contamination of the stainless steel terminal were evaluated in the same manner as in Example 1. Further, the obtained thermal transfer sheet and the image receiving sheet prepared in Example 1 were superposed to form a laminate, and the image quality was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative Examples 6 to 8) In Example 1, the compound A-1 represented by the following structural formula was used instead of the slipping agent used for preparing the coating solution for the image forming layer, and the results are shown in Table 1. A thermal transfer sheet was prepared in the same manner as in Example 1 except that the addition was performed so that the coating amount was obtained, and the static friction coefficient and the surface contamination of the stainless steel terminal were evaluated in the same manner as in Example 1. Further, the obtained thermal transfer sheet and the image receiving sheet prepared in Example 1 were superposed to form a laminate, and the image quality was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Comparative Examples 9 to 11) In Example 1, the compound A-2 represented by the following structural formula was used in place of the slipping agent used for preparing the coating solution for the image forming layer, and the coating shown in Table 1 was used. A thermal transfer sheet was prepared in the same manner as in Example 1 except that the amount was added so as to be the amount, and the static friction coefficient and the surface contamination were evaluated in the same manner as in Example 1. Also, the obtained thermal transfer sheet,
The image receiving sheet produced in Example 1 was overlaid to form a laminate, and the image quality was evaluated in the same manner as in Example 1. Table 1 shows the results.

[0091]

Embedded image

[0092]

[Table 1] From the results in Table 1, it can be seen that using the thermal transfer sheets of the present invention of Examples 1 to 10 having a static friction coefficient of 0.35 or less,
It can be seen that a good image can be obtained even if laser image recording is performed successively. This is because there is no roll contamination when conveying the thermal transfer sheet. On the other hand, when the thermal transfer sheets of Comparative Examples 1 to 11 having a coefficient of static friction of more than 0.35 are used, it can be seen that the image is stained. This is considered to be due to roll contamination when the thermal transfer sheet is conveyed, as can be seen from the evaluation result of the surface contamination of the stainless terminal.

[0093]

According to the present invention, it is possible to provide a thermal transfer sheet capable of forming a good image without roll contamination when the thermal transfer sheet is conveyed, and an image forming material using the same.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a thermal transfer sheet of the present invention.

FIG. 2 is a diagram schematically illustrating the steps of an image forming method using the image forming material of the present invention.

[Explanation of symbols]

 Reference Signs List 10 thermal transfer sheet 12 support 14 light-to-heat conversion layer 16 image forming layer 20 image receiving sheet 22 image receiving sheet support 24 cushion layer 26 image receiving layer 30 laminate 40 laser light

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H025 AA13 AA17 AB09 AC08 AD01 CA41 CA42 DA01 DA03 DA05 FA10 2H111 AA01 AA12 AA17 AA26 AA35 BA02 BA03 BA07 BA09 BA38 BA55 BA61 BA64 BA74 BA76 CA03 CA04 CA12 CA25 CA45

Claims (7)

[Claims] In a thermal transfer sheet having at least one light-to-heat conversion layer and at least one image forming layer on a support, the coefficient of static friction of the outermost layer on the side where the image forming layer is coated is provided. Is not more than 0.35. 2. The thermal transfer sheet according to claim 1, wherein the coefficient of static friction is 0.20 or less. 3. The thermal transfer sheet according to claim 1, wherein the outermost layer is an image forming layer. 4. The thermal transfer sheet according to claim 1, wherein the photothermal conversion layer contains an infrared absorbing dye. 5. The thermal transfer sheet according to claim 1, wherein the outermost layer contains a monoester of a fatty acid having 9 to 27 carbon atoms and an alcohol having 2 to 5 OH groups. 6. The thermal transfer sheet according to claim 1, wherein an image is formed by imagewise exposing using a laser having a wavelength of 750 nm or more. 7. An image comprising a support having an air gap, an image receiving sheet having a cushion layer and an image receiving layer thereon, and the thermal transfer sheet according to any one of claims 1 to 6. Forming material.