JP2988665B2 - Transfer sheet for image recording - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a thermal transfer recording by a thermal recording device such as a thermal printer, or an image recording used for photosensitive pressure-sensitive recording using a photo-curable microcapsule. It relates to a sheet to be transferred.

(B) Prior Art In recent years, thermal transfer recording for forming a transfer image on plain paper using a thermal printer, a thermal facsimile or the like has been actively developed. This thermal transfer recording is easy to maintain due to the simple mechanism of the apparatus, low in cost and fiber cost, and low-energy, clear and robust recording is possible. Recently, it has been widely used because color recording can be easily performed.

In particular, with respect to color thermal transfer recording, for CAD / CAM, color copying machines, video printers and the like, high-definition recording with good gradation reproducibility has been demanded. Various improvements have been made to the thermal head in terms of the device, and to the material, physical properties, and layer structure of the heat-fusible ink for the thermal transfer film, and to the recording method.

Also, the transfer paper has high smoothness, ink oil absorption,
Improvements such as air permeability have been made.

For example, there are the following known techniques for receiving paper. As disclosed in Japanese Patent Application Laid-Open No. Sho 60-255487, it is disclosed that tone receiving properties are obtained on an image receiving paper coated with a heat-fusible substance having a melting point higher than the melting point of the heat-fusible ink.

As disclosed in JP-A-57-182487, an image-receiving layer containing an oil-absorbing pigment having an oil absorption of 30 ml / 100 g or more (based on JIS K5101) is provided on the surface of an image-receiving sheet so that the image is stable and has no unevenness in density. It discloses that a recorded image is obtained.

On the other hand, photosensitive pressure-sensitive recording using photocurable microcapsules is performed by the following recording method. It is composed of a transfer sheet in which microcapsules are coated on a support and a transfer sheet represented by plain paper. At least one of the film of the microcapsules on the transfer sheet, the internal phase,
It is composed of a substance whose physical properties are changed by giving light, heat, or light and heat. A latent image is formed imagewise on the transfer sheet by this property. The internal phase of the microcapsules contains a colorant, which corresponds to an oil-based ink. The transfer sheet on which the latent image is formed is combined with the transfer sheet,
Given pressure, heat, or pressure and heat. As a result, the microcapsules in the image area are destroyed, and the inner phase, that is, the ink, is transferred to the image receiving sheet to obtain a recorded image.

As an example, JP-A-62-39844 discloses a method in which a photocurable resin and colored dyes and pigments are encapsulated in microcapsules and imagewise exposed to form a latent image, that is, by polymerizing a polymerizable compound in an exposed portion. By hardening the microcapsules and then applying pressure in combination with the sheet to be transferred, the uncured microcapsules are broken, and the colorant released is transferred to the sheet to be transferred. A pressure sensitive recording sheet is disclosed.

In JP-A-62-39845, a heat-meltable substance is used as a film material, and a photocurable resin or a microcapsule comprising an inner phase as a colored dye or pigment dissolved or dispersed in a photocurable resin and an organic solvent is used. A photosensitive thermal transfer type recording sheet which obtains an image by pressing and heating a combination of a transfer sheet and plain paper as a transfer sheet is disclosed.

(C) Problems to be Solved by the Invention There are various problems in the patent gazettes cited in the above prior art.

For example, in the case of thermal transfer recording, when a heat-fusible substance is applied to an image-receiving paper (transfer-receiving sheet), the resulting transferred image has a problem with long-term storage stability, particularly thermal stability.
In the case of an image receiving sheet (transferred sheet) provided with an image receiving layer containing an oil absorbing pigment, the heat fusible ink depends on the melt viscosity of the ink and the amount of oil absorbed by the pigment, resulting in a high-definition transferred image. There was room for improvement to get.

On the other hand, in photosensitive pressure-sensitive recording, plain paper has conventionally been used as a transfer-receiving sheet. But,
The image quality of plain paper is insufficient in terms of the density, color, resolution, and the like of the obtained image, and a high-quality image cannot be obtained. Especially in a color image, cyan,
In general, a method is used in which inks of colors such as magenta and yellow are transferred in a superimposed manner to mix colors, so that a high-quality color image cannot be obtained.

(D) Means for Solving the Problems The inventors of the present invention have conducted intensive studies, and as a result, provided a transfer sheet for image recording capable of obtaining a high-definition recorded image with good gradation reproducibility. It is.

That is, the transfer sheet for image recording provided by the present invention is obtained by coating a heat insulating layer having a void structure on a base material, and the heat insulating layer mainly contains polymer microspheres. Is what you do.

The polymer microsphere used for the heat insulating layer is composed of hollow resin particles or particles having a different phase structure.

Further, the hollow resin particles are made of a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin, and the hetero-phase structure particles are polyethyl acrylate-polystyrene copolymer resin, polybutyl acrylate-polystyrene. It is composed of a copolymer resin or a polymethyl methacrylate-polystyrene copolymer resin.

The transfer sheet for image recording used in the present invention can obtain a high-definition with gradation reproducibility and a transfer image with good transfer efficiency in color image recording in thermal transfer recording and photosensitive pressure-sensitive recording.

In addition, the same effect can be obtained in the recording of a monochrome image, and it can be used as receiving paper of an ink jet recording system which requires ink absorptivity.

 Hereinafter, the present invention will be described specifically.

The transfer sheet for image recording of the present invention will be described with reference to thermal transfer recording. The heat-meltable ink layer side of the thermal transfer film and the heat-insulating layer side of the transfer-receiving sheet provided with a heat-insulating layer made of polymer microspheres on the substrate are superimposed, and thermal recording is performed with a thermal head from the non-ink layer side of the thermal transfer film. Perform
When the energy applied by the thermal head is applied to the thermal transfer film, the heat-meltable ink melts and penetrates into the void structure in the heat insulating layer. Further, since the heat insulating layer has minute voids, heat of the thermal head is stored in the heat insulating layer.

For this reason, the applied energy required for thermal recording can be reduced. That is, transfer recording is possible even when the applied energy is reduced, and a transferred image with good tone reproducibility can be obtained by recording stepwise from low to high applied energy. Also, the recording becomes high definition.

In the photosensitive pressure-sensitive recording, the internal phase oil containing the dye and pigment encapsulated in the microcapsules is released due to the breakage of the microcapsules by pressure, but easily penetrates into the void structure portion of the heat insulating layer portion of the sheet to be transferred. As a result, an efficient transfer image can be obtained. In addition, heating may be used at the time of pressurization. As in the case of thermal transfer paper, thermal efficiency is improved by heat storage in the heat insulating layer, and the viscosity of the capsule contents is further reduced, so that transfer efficiency is improved.

In the present invention, as the polymer microspheres used for the heat insulating layer of the image-receiving sheet, hollow resin particles and hetero-phase structure particles serve the purpose of the present invention.

Hollow resin particles are resin particles having voids inside,
It has a particle size on the order of submicron to several tens of μm. Due to the internal voids, the layer applied on the substrate has a heat insulating effect due to the air contained therein. The voids between the particles of the coating layer have an oil absorbing effect. The shell of the hollow resin particles can change the pores to be coarse, microporous, and nonporous, and thus can also impart oil absorbency.

Heterophase structured particles are produced by seed emulsion polymerization method.
It is a composite polymer emulsion particle in which two or more kinds of polymer molecules coexist in the particle, and has a form such as gold rice sugar, a snowman, a wild strawberry, and a star.

These production methods use a polymer A particle produced by emulsion polymerization as a seed, and a monomer B is seed-emulsion-polymerized therein, thereby finally producing A / B composite particles composed of two types of polymer molecules. It is. The heterogeneous polymers form a heterophase structure in which phases are separated.

Since the hetero-phase structure particles having such a unique morphology are bulky, the coating layer on the substrate becomes a coating layer having a heat insulating property by having a void structure. Further, the void portion has a function as an oil absorbing property.

If the hollow resin particles and the hetero-phase structure particles are specifically exemplified, as the hollow resin particles, polystyrene, a styrene-based resin such as poly-γ-methylstyrene, polymethyl methacrylate, an acrylic resin such as polyethyl methacrylate, Styrene-acrylic copolymer resins and the like can be mentioned.

Examples of the hetero-phase structure particles include polyethyl acrylate-polystyrene copolymer resin, polybutyl acrylate-polystyrene copolymer resin, and polymethyl methacrylate-polystyrene copolymer resin.

In the present invention, these particle diameters are 10 μm or less in outer diameter,
Preferably it is 5 μm or less, more preferably 3 μm or less.

The heat insulating layer of the transfer sheet for image recording used in the present invention mainly comprises a combination of a polymer microsphere and a binder.

The mixing ratio of the polymer microspheres and the binder is adiabatic,
From the oil absorption property side, the binder is 5 to 100 parts by weight based on 100 parts by weight of the polymer microsphere, preferably 10 to 50 parts by weight based on 100 parts by weight of the polymer microsphere, and more preferably coated paper. Considering the dusting on the super calender during the production of the polymer, the amount is 15 to 30 parts by weight based on 100 parts by weight of the polymer microsphere.

In the combination of polymer microspheres and binder, inorganic pigments and organic pigments (spherical particles other than hollow resin particles) are used together within a range that does not impair the heat insulating properties in order to make oil absorption more effective in addition to heat insulating properties. May be.

Specifically, as the inorganic pigment, for example, clay, talc, calcium carbonate, calcium sulfate, barium sulfate,
Titanium oxide, zinc oxide, zinc sulfide, satin white, silicon oxide, zeolite, magnesium hydroxide, basic magnesium carbonate, alumina, synthetic silica, calcium silicate, diatomaceous earth, aluminum hydroxide, etc. Benzoguanamine resin, polyethylene, polystyrene, urea-formalin resin, polyamide resin and the like.

As the binder used in the present invention, a water-soluble polymer,
Synthetic resin latex and resins soluble in organic solvents can be used. Examples of the water-soluble polymer include oxidized starch, etherified starch, starches such as dextrin, carboxymethylcellulose, cellulose derivatives such as hydroxyethylcellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its derivatives, maleic anhydride resin, Further, a copolymer of two or more components of maleic anhydride and ethylene, styrene, isobutadiene, vinyl acetate, or the like is used. Examples of the synthetic resin latex include ordinary styrene-butadiene copolymer, conjugated diene-based polymer latex such as methyl methacrylate-butadiene copolymer, and acrylic such as acrylate and methacrylate polymer or copolymer. Polymer latex,
A vinyl-based polymer latex such as an ethylene-vinyl acetate copolymer, or a functional group-modified polymer latex with a functional group-containing monomer such as a carboxyl group of these various polymers;
Are used. As a resin soluble in an organic solvent, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, melamine resin, phenol resin, polyurethane,
A polyamide resin, an alkyd resin, or the like is used.

In the configuration of the heat insulating layer, if necessary, a dispersant, a thickener, a flow modifier, an antifoaming agent, a foam inhibitor, a release agent, a coloring agent,
The addition of a preservative, a pH adjuster or the like as appropriate does not matter at all as long as the properties are not impaired.

As the substrate used in the present invention, an opaque, translucent, or transparent support is used, and paper, synthetic paper, cloth, nonwoven fabric, glass, metal, cellophane, wood, synthetic resin film, and the like are used.

The coating method of the present invention includes aqueous coating and solvent coating depending on the combination of the above configurations. As a coating machine, any of a blade coater, a roll coater, a brush coater, a curtain coater, a chaplex coater, a bar coater, a gravure coater and the like can be applied. Drying after coating is performed by a usual drying method, for example, various methods such as a gas heater, an electric heater, a steam heater, and hot air heating to obtain a coated sheet.

The heat insulating layer is applied on the support at a dry coating amount of about 1 to 60 g / m ² . Preferably, the dry coating amount is about ² to 40 g / m ² . The required amount of coating may be provided at one time, or the required amount may be obtained by two or more coatings.

A transfer sheet in which only a heat insulating layer is provided on a base material is inferior in smoothness and may lower the image quality of an obtained image.
Therefore, as described above, after coating and drying, it is also possible to improve the finish of the image by giving the surface smoothness using, for example, a super calender or a gloss calender.

(E) Function The transfer sheet for image recording of the present invention has a heat insulating layer having a void structure on a base material. In thermal transfer recording, a high-definition transfer image with good tone reproducibility was obtained, and in photosensitive pressure-sensitive recording, a transfer image with good transfer efficiency was obtained.

(F) Example Hereinafter, the present invention will be specifically described with reference to examples. In addition, "part" shows a weight part.

(Preparation of thermal transfer film) A heat-resistant layer was coated on one side of a 6 μm-thick polyester film, and a hot-melt ink having the following composition was coated on the opposite side to a thickness of 3.0 μm using a hot melt coater. And a thermal transfer film.

13 parts by weight of carbon black Synthetic carnauba wax 40 Paraffin wax (155 ° F) 40 Ethylene-vinyl acetate copolymer 2 Petroleum resin 5 (Preparation of photosensitive pressure-sensitive recording transfer sheet) Photo-curable microcapsules containing cyan dye Production: 10% aqueous solution of ethylene-maleic anhydride copolymer
A solution was prepared by mixing 100 parts, 10 parts of urea, 1 part of resorcinol and 200 parts of water, and the pH was adjusted to 3.5 using an aqueous sodium hydroxide solution.

Separately, epoxy acrylate-based photocurable resin (trade name:
Lipoxy, manufactured by Showa Polymer Co., Ltd.) was dissolved in advance with 14.4 parts of cyan dye orazole blue in 165.6 parts, and then, under light shielding, 2,2-dimethoxy-2-phenylacetophenone (trade name: Irgacure 651, 0.8 part (Civer Kaigie Co., Ltd.) was added and emulsified and dispersed in the mixed aqueous solution to obtain an oil-in-water emulsion having oil droplets of 4 to 8 microns. Next, 2.5 parts of a 37% formaldehyde aqueous solution was added, the solution temperature was kept at 55 ° C., stirring was continued for 4 hours, and then cooled to room temperature to complete microencapsulation.

Further, under shading, 30 parts of this microcapsule and 20 parts of wheat starch as a stilt, 10 parts of paraffin wax
Parts, and 10 parts of SBR latex were blended and coated on a base paper having a basis weight of 50 g / m ² using a Meyer bar to obtain a photosensitive and pressure-sensitive recording transfer sheet.

Example 1 A base paper having a basis weight of 50 g / m ² was coated with a coating solution for a heat insulating layer having the following composition using an air knife coater so as to have a coating amount of 10 g / m ^2, and the surface was smoothed with a super calender. To give a transfer sheet for image recording. The polyacryl-polystyrene copolymer is a hetero-phase structure particle having a particle diameter of 1.0 μm, and has a morphological shape like spinous sugar.

Polyacrylic-polystyrene copolymer 100 parts by weight XMRP-100 (Mitsui Toatsu Chemicals) Ethylene-vinyl acetate copolymer 15 parts by weight OM-4000 (Kuraray) Comparative Example 1 Thermal transfer as a transfer sheet for image recording Recording paper (Mitsubishi Paper, trade name: TTR-T) was used.

Examples 2 to 13 and Comparative Examples 2 to 4 In the same manner as in Example 1, as shown in Table 1, polymer microspheres were respectively changed to prepare transfer sheets for image recording.

Table 1 shows the amount of the binder per 100 parts by weight of the polymer microspheres for the blending of the polymer microspheres and the binder. All of the hetero-phase structure particles used in Examples 11 to 13 are in the form of confetti. In Comparative Example 4, urea resin particles which are non-hollow resin particles were used.

Example 14 In the same manner as in Example 1, a transfer sheet for image recording was prepared with the following composition.

Polyacrylic-polystyrene copolymer XMRP-10
0 (manufactured by Mitsui Toatsu Chemicals) 100 parts by weight Calcined Kaolin ASICS (manufactured by Engelhard) 20 parts by weight Ethylene-vinyl acetate copolymer OM-4000 (manufactured by Kuraray) 24 parts by weight Comparative Example 5 Generally used as a transfer sheet for image recording Plain paper (Xerox paper) was used.

Evaluation 1. Thermal transfer recording The thermal fusible ink side of the thermal transfer film and Examples 1 to
14 and the transfer sheet for image recording prepared in Comparative Examples 1 to 4 were superimposed on the heat-insulating layer coating side, and evaluated by the following test method. The results are shown in Table 2.

Gradation Using a thermal head printer manufactured by Matsushita Electronic Components Co., Ltd., solid printing was performed by changing the applied energy from 0.27 to 2.0 mJ.

Those having a linear tendency between the density obtained by printing and the applied energy were represented by △, Δ, and ×, and those with no ○ were represented by x.

Using the same apparatus as for high definition, half printing was performed at an applied energy of 0.27 mJ, and the fineness due to the transfer of fine lines was represented by 、, Δ, and X, with good being X and poor being fine.

Adhesion A mending tape (Scotch tape) was adhered to the coated layer portion of the heat insulating layer of the transfer sheet for image recording, and the adhesion of the coated layer was evaluated by observing the peeling of the coated layer.

2. Photosensitive pressure-sensitive recording The image quality was evaluated by using the above-mentioned photosensitive pressure-sensitive recording transfer sheet, applying pressure between the rubber rolls by superimposing the image-recording transfer sheets of Examples 1 to 14 and Comparative Examples 1 to 4. The image quality of the obtained image was evaluated. The results are shown in Table 2.

Image Density The reflection density of cyan was measured with a reflection densitometer Macbeth RD-918 (manufactured by Macbeth).

Color of Image The color of the obtained image was represented by △, Δ, and ×, with good color being 良 い and bad color being ×.

From the results shown in Table 2, when the amount of the binder per 100 parts by weight of the polymer microspheres is large (Comparative Example 3), the thermal transfer recording (gradation and high definition) is inferior. Is inferior in adhesiveness. Further, in the photosensitive pressure-sensitive recording, the image density is low in Comparative Examples 3 and 4. In Comparative Example 2, although the image density was high, the coating layer was peeled off, which is not preferable.

(G) Effect of the Invention The transfer sheet for image recording of the present invention can obtain a high-definition image with high tone reproducibility and high transfer efficiency in thermal transfer recording and photosensitive pressure-sensitive recording, and is of industrial significance. It is extremely expensive.

Claims (5)

(57) [Claims] 1. A transfer sheet for image recording comprising a substrate and a heat insulating layer having a void structure as an image receiving layer,
The heat-insulating layer mainly contains polymer microspheres composed of hollow resin particles or heterophase structure particles, and the mixing ratio of the polymer microspheres and the binder is 5 to 100 parts by weight of the binder with respect to 100 parts by weight of the polymer microspheres. A sheet to be transferred for image recording, characterized in that the sheet is a part. 2. The transfer sheet for image recording according to claim 1, wherein said polymer microspheres comprise hollow resin particles. 3. The transfer sheet for image recording according to claim 2, wherein said hollow resin particles are made of a styrene resin, an acrylic resin, or a styrene-acrylic copolymer resin. 4. The transfer sheet for image recording according to claim 1, wherein said polymer microspheres are composed of particles having a different phase structure. 5. The method according to claim 1, wherein the hetero-phase structured particles are polyethyl acrylate.
The transfer sheet for image recording according to claim 4, comprising a polystyrene copolymer resin, a polybutyl acrylate-polystyrene copolymer resin, or a polymethyl methacrylate-polystyrene copolymer resin.