JPH05169845A - Image-receiving sheet for thermal transfer recording - Google Patents

Abstract

PURPOSE:To obtain high recording sensitivity by forming an intermediate layer containing composite thermoplastic resin particulates, surfaces of which are coated with inorganic powder, between an image-receiving layer and a supporter in the title sheet with the image-receiving layer receiving a transfer image from a coloring-material transfer sheet. CONSTITUTION:In an image-receiving sheet for thermal transfer recording, in which an image-receiving layer receiving a transfer image from a coloring- material transfer sheet is formed onto a supporter, an intermediate layer containing composite thermoplastic resin particulates, surfaces of which are coated with inorganic powder, is formed between the image-receiving layer and the supporter. The composite thermoplastic resin particulates, surfaces of which are coated with inorganic powder, are acquired by bringing the co- called thermoplastic resin particulates such as a condensation resin represented by a nylon group, a polyester group, etc., and/or polymerization addition resin particulates represented by a polyurethane group, an epoxy group, etc., addition polymerization resin particulates, etc., represented by vinyl resin particulates into contact with inorganic powder under heated conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image-receiving sheet for thermal transfer recording, and more particularly to an improvement of an image-receiving sheet for thermal transfer recording using a heat sublimable dye, which has a remarkably improved recording sensitivity and recording image quality. Is provided.

[0002]

2. Description of the Related Art A thermal recording system, which can obtain a recorded image at the same time as an input signal, is used in various fields such as facsimiles, computer terminal printers, measuring instrument printers, etc., because it is relatively simple and inexpensive and has low noise. Has been done. As a recording medium used in these thermal recording systems, so-called color-developing type heat-sensitive recording paper, which is provided with a recording layer that undergoes a physical or chemical change by heating to develop a color, is most commonly used. However, color-type thermosensitive recording paper is liable to cause unwanted color development during the manufacturing process and during storage, and is also inferior in storage stability of the recorded image, causing fading due to contact with organic solvents and chemicals. There is a drawback that it is easy to cause.

Therefore, as a recording medium replacing the color-developing type thermosensitive recording paper, a system using a recording medium utilizing a colored coloring material itself has been proposed, for example, Japanese Patent Laid-Open No. 51-51.
In JP-A-15446, a color material which is solid or semi-solid at room temperature is applied on a support such as paper or polymer film, and the color material on the support is brought into contact with a recording paper to perform thermal recording. A method has been proposed in which a coloring material on a support is heated by a head and selectively transferred to recording paper to obtain a recorded image.

In this recording system, the coloring material on the support is melted, evaporated and sublimated by heat and transferred to recording paper to obtain a recorded image by adhesion, adsorption and dyeing, and plain paper is also used as recording paper. There are features available. In particular, in a recording method using a sublimable dye as a color material, an image excellent in gradation can be obtained, and therefore application development for full-color recording is underway.

However, when plain paper is used as the recording paper, dyeing is difficult to occur, sufficient color density is difficult to obtain, and a remarkable fading phenomenon occurs over time. Therefore, JP-A-57-107885 and US Pat.
An image receiving sheet in which an image receiving layer containing a thermoplastic resin as a main component is formed is proposed in JP-A-601484 and the like. By forming an image-receiving layer containing a thermoplastic resin as a main component, the recording sensitivity and storage stability are improved, but when the support is plain paper, a uniform image-receiving layer cannot be obtained, and the recording sensitivity, The image quality was insufficient. Therefore, JP-A-60-2367
No. 94, JP-A-61-144394, etc., an intermediate layer such as a thermoplastic resin is interposed between a support and an image receiving layer, and a color material layer of a color material transfer sheet is used at the time of printing. There has been proposed a method for improving the recording sensitivity and the image quality by improving the adhesion between the image receiving sheet and the image receiving layer to prevent air gaps and the like from occurring.

It has also been proposed that the intermediate layer be composed of fine resin particles made of a specific thermoplastic resin to further improve the image quality (Japanese Patent Laid-Open Nos. 63-87286 and 64-27996. Under the circumstances, Japanese Patent Laid-Open Nos. 1-136784 and 2-139293 do not provide satisfactory image quality.

On the other hand, it has been proposed to obtain good image quality and recording sensitivity by using a synthetic paper or a white film as a support, but it is deformed by heat applied at the time of recording and is expensive. There are still problems such as the fact that it is a different material, and it was not satisfactory.

[0008]

In view of the present situation, the present inventors have earnestly studied the improvement of an image-receiving sheet for thermal transfer recording which is useful in a recording system in which a colored coloring material, particularly a heat sublimable dye, is thermally transferred. The present invention has completed an image-receiving sheet which has an extremely high recording sensitivity and provides a recording layer of high image quality which is extremely excellent in resolution, sharpness, color density, dot dropout and the like.

[0009]

The present invention provides a thermal transfer recording image-receiving sheet comprising a support and an image-receiving layer for receiving a transfer image from a color material transfer sheet, which is provided between the image-receiving layer and the support. An image-receiving sheet for thermal transfer recording, characterized in that an intermediate layer containing composite thermoplastic resin fine particles whose surface is coated with an inorganic powder is provided on.

[0010]

In the image-receiving sheet of the present invention, the fine particles of the composite thermoplastic resin surface-coated with the inorganic powder constituting the intermediate layer are condensation type resins typified by nylon type and polyester type and / or polyurethane type and epoxy type. It can be obtained by contacting so-called thermoplastic resin particles such as poly-addition type resin particles typified by 1 and addition polymerization type resin particles typified by vinyl-based resin particles with inorganic powder under heating conditions.

Such thermoplastic resin fine particles are directly produced when producing a resin by emulsion polymerization, suspension polymerization, etc., liquid granulation in a non-solvent, further freeze pulverization, wet pulverization. It is manufactured by processing after the resin is manufactured by a mechanical granulation method such as a method. Among the resin fine particles as described above, the vinyl resin particles are particularly preferably used because the physical property values can be easily controlled by selecting the monomer and the fine particles can be easily produced.

The vinyl resin particles are synthesized by a so-called polymerization method by selecting one or more suitable monomers, and preferably in the form of an aqueous dispersion by an emulsion polymerization method, a suspension polymerization method or the like. Specific examples of the main component monomer include, for example, styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 4-methoxystyrene, vinyl chloride, vinylidene chloride, ethylene, vinylcyclohexane, methyl methacrylate, hexyl acrylate. , Vinyl acetate, acrylonitrile, and other vinyl-based monomers. For example, 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene and other rubber-based monomers are added to the resin particles to obtain a melting point and a softening point, The melting point, softening point and glass transition point of the resin particles can be increased by lowering the glass transition point or adding a crosslinking agent such as divinylbenzene.

Further, in order to modify the surface characteristics of the resin particles, an α, β-ethylenically unsaturated carboxylic acid monomer such as acrylic acid, methacrylic acid, maleic acid, itaconic acid or fumaric acid is added and copolymerized. It can also be modified by a polymer reaction or the like. Furthermore, it is also possible to modify the so-called ionomer resin by metal crosslinking. Furthermore, it is also possible to use non-expandable hollow resin fine particles having internal voids during the production of such thermoplastic resin fine particles, heat expandable resin particles containing a foaming agent that can be used as hollow resin particles by being foamed by heating when necessary. is there.

As the inorganic powder used for the surface coating of such thermoplastic resin fine particles, so-called inorganic pigments used in the general coating field are used, for example, clay, kaolin, combustion kaolin, delaminated kaolin. , Structural kaolin, aluminum hydroxide,
Aluminum oxide, heavy calcium carbonate, light calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, talc, silica and the like can be mentioned. In order to efficiently carry out the following surface coating, the above-mentioned thermoplastic resin fine particles The particle size of 1/10 or less of the particle size is preferably selected and used.

Coating of these inorganic powders on the surface of the thermoplastic resin fine particles can be carried out by any method such as a so-called mechanochemical reaction method or a so-called solvent coating method, but preferably, the thermoplastic resin is used. Under heating conditions where the surface of the resin fine particles may exhibit thermoplasticity,
Thermoplastic resin fine particles and inorganic powder in a free flowing gas,
A method of carrying out stirring and contact is selected.

Among them, as exemplified in US Pat. No. 4,722,943, heat-expandable resin fine particles are used as the thermoplastic resin fine particles, and surface coating of the inorganic powder, foaming of the heat-expandable resin fine particles, and formation of hollow fine particles are simultaneously performed. The composite thermoplastic resin fine particles obtained by the method of advancing are markedly effective in the present invention and are preferably used.

The composite thermoplastic resin fine particles surface-coated with the inorganic powder as described above may be used, if necessary.
An intermediate layer is formed by forming a coating liquid with binders and auxiliaries, coating on a support, and drying. Examples of binders include modified starch, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and casein. , Natural or semi-synthetic polymers such as gelatin and natural rubber; polydienes such as polyvinyl alcohol, isoprene, neoprene and polybutadiene; polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene; vinyl halides, vinyl acetate, styrene, (meth) ) Acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, vinyl polymers such as methyl vinyl ether and copolymers, polyesters, polyurethanes, polyamides, styrene-butadiene series, methyl methacrylate Examples include so-called coating binders such as synthetic polymers such as synthetic rubber latexes such as butadiene, maleic acid, and the like. Among them, at least one binder that can exhibit thermoplasticity in the recording energy range is selected and used. desirable.

It is needless to say that the amount of these binders used is arbitrarily selected within a range that does not impair the action and effect of the composite thermoplastic resin fine particles surface-coated with the inorganic powder constituting the intermediate layer. However, it is generally 500% by weight or less, more preferably 0.01 to
200% by weight is used. In addition to the above-mentioned composition constituting the intermediate layer, if necessary, calcium carbonate, talc,
Although it is possible to add inorganic or organic pigments such as kaolin, titanium oxide, aluminum hydroxide, zinc oxide, urea / formaldehyde resin fine particles, melamine resin fine particles, guanamine resin fine particles, etc., of the composite thermoplastic resin fine particles used in the present invention, Used within a range that does not impair the effects.

Further, for example, addition of dyes, pigments and / or fluorescent dyes for controlling color tone and whiteness, addition of ultraviolet absorbers for improving storage stability, antioxidants, etc., for imparting smearability, Various auxiliaries such as addition of a dispersant, a wetting agent, a defoaming agent and the like can also be added. If the thickness of the intermediate layer is less than 1 μm, the desired effect of the present invention cannot be expected, so 1 μm or more, more preferably 3 to 50.
An intermediate layer having a film thickness of about μm is formed.

By subjecting the intermediate layer thus formed to a smoothing treatment before or after forming the image receiving layer, the recording sensitivity of the image receiving sheet obtained can be further enhanced. The smoothing treatment is appropriately performed, for example, by heating / pressurizing treatment with a super calender, a cast drum, or the like. However, when the average particle diameter of the composite thermoplastic resin fine particles forming the intermediate layer is 0.1 μm or less, the smoothing treatment is performed. However, if it exceeds 100 μm, not only the coating suitability but also the effect of the smoothing treatment cannot be expected.
It is desirable to adjust in the range of about 50 μm.

In the image-receiving sheet of the present invention, the image-receiving layer provided on the intermediate layer is not particularly limited, but generally a thermoplastic resin layer having an effective dyeing ability for a sublimable dye is preferable. Used. Examples of the thermoplastic resin constituting the image receiving layer include polymers and copolymers of vinyl monomers such as styrene, vinyltoluene, acrylic acid ester, methacrylic acid ester, acrylonitrile, vinyl chloride and vinyl acetate; polyester,
Examples thereof include condensation polymers such as polyamide, polycarbonate, polysulfone, epoxy resin and polyurethane; and cellulose resins.

These thermoplastic resins may be used alone, or two or more kinds of resins having different properties may be used in combination. In addition, if necessary, other resin materials such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine resin, urea resin, urethane resin, epoxy resin, silicone resin, and fluororesin. May be contained, and it is also possible to modify the image receiving layer by adding a reactive compound such as a polyvalent isocyanate compound, an epoxy compound or an organometallic compound. However, it is necessary to keep the thermoplastic synthetic resin forming the image receiving layer within the range in which the thermoplasticity is not lost.

Further, for the purpose of improving the writing property, for example, heavy and light calcium carbonate, talc, clay, natural and synthetic silicic acids, titanium oxide, aluminum hydroxide, zinc oxide, urea formaldehyde resin powder, etc. are formed on the image receiving layer. It is also possible to add various auxiliaries such as inorganic and organic pigments, ultraviolet absorbers, antioxidants, antistatic agents, release agents and lubricants. The coating amount of the constituent components forming the image receiving layer on the intermediate layer is appropriately selected according to the purpose of use of the image receiving sheet, etc., but is generally about ² to 15 g / m ^{2 in} dry weight. ..
As the support, plain paper, synthetic paper, synthetic resin film or the like is appropriately selected and used, but plain paper is preferably used because it has excellent thermal characteristics. Further, the plain paper referred to herein is, for example, a paper obtained by ordinary paper-making with cellulose pulp as a main component and adding a paper-strengthening agent, a sizing agent, a fixing agent, an inorganic and an organic filler, and the like. Included are papers whose surface properties have been improved by size-pressing oxidized starch and the like, or by providing a precoat layer containing a pigment such as clay as a main component.
Paper having excellent surface smoothness such as art paper, coated paper, cast coated paper and the like is particularly preferably used.

These supports may be provided with an image-receiving layer after providing an intermediate layer. If necessary, before providing the intermediate layer and / or
Alternatively, for the purpose of controlling adhesiveness, barrier property, smoothness, concealment property, etc., it is also optional to further provide an anchor coat layer, or to extrude a laminate or bond a thin film substrate, and known materials and methods may be used. Available.

On the image-receiving layer, for example, Japanese Patent Laid-Open No. 59-59
No. 165688, JP-A No. 61-27290, etc., a thin heat-resistant release layer containing a silicon-based resin having a property of transmitting a sublimation dye as a main component is formed, It is also possible to prevent the dye or dye layer from being directly transferred from the color material transfer sheet.

The thus-obtained image-receiving sheet for thermal transfer recording of the present invention exhibits extremely excellent performance particularly as an image-receiving sheet when a sheet containing a heat sublimable dye is used as a color material transfer sheet, It has excellent recording sensitivity and can provide a recorded image with high image quality, which is extremely excellent in resolution, definition, color density, dot dropout, and the like.

Although the reason why such an excellent effect is obtained is not always clear, the composite thermoplastic resin fine particles surface-coated with the inorganic powder which is a constituent component of the intermediate layer exert their characteristics during thermal transfer recording. It is presumed that this is to uniformly control the heat transfer from the recording head and to improve the adhesion between the color material transfer sheet and the image receiving sheet.

The heat sublimable dye referred to in the present invention does not cause the transition of the coloring material even when it comes into contact with the image receiving sheet under normal handling conditions, but it is first melted, evaporated or sublimated by heating at 60 ° C. or higher. Etc. means a dye that causes a transition of a coloring material, for example, an azo type, a nitro type, an anthraquinone type, a disperse dye represented by a quinoline type, a triphenylmethane type, a basic dye represented by a fluorane type, It is used by appropriately selecting from various dyes such as oil-soluble dyes.

Further, the image-receiving sheet for thermal transfer recording of the present invention is not limited to the thermal recording system of contact heating with a thermal plate of a thermal printing unit, a thermal head, etc., but also a heat ray of an infrared lamp, a YAG laser, a carbon dioxide laser, etc. It is also useful for thermal recording by a non-contact heating method using radiation.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

[0031]

Example 1 Composite thermoplastic resin hollow fine particles coated with titanium oxide powder (trade name: F-30)
GS / TiO ₂ , particle size: 8 to 20 μm, hollow fine particles /
Inorganic powder ratio: 15/85, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 100
Part, polyvinyl alcohol (PVA-205, manufactured by Kuraray Co., Ltd.) 5 parts, polystyrene-acrylic copolymer latex (trade name: Sebian A-4720, manufactured by Daicel) 15
Water was added to the parts to prepare an intermediate layer coating liquid having a solid content concentration of 30%. Commercially available high-quality paper (trade name: TKP)
-13, basis weight 81 g / m ² , manufactured by Kanzaki Paper Co., Ltd.) and dried so that the dry weight was 10 g / m ² . Then
Aqueous polyester resin (Product name: Bayronal MD-1
200, solid content 34%, manufactured by Toyobo Co., Ltd.) is applied and dried on the intermediate layer so that the dry weight is 8 g / m ^2, and an image receiving layer is formed. Smoothing treatment with a super calender (linear pressure 20
0 kg / cm).

Next, a saturated polyester resin (trade name:
Byron 200, manufactured by Toyobo Co., Ltd. 100 parts, amino-modified silicone oil (trade name: KF-393, manufactured by Shin-Etsu Silicone Co., Ltd.) 1.5 parts, epoxy-modified silicone oil (trade name: X-22-343, Shin-Etsu Scientific Industry Co., Ltd.) (Manufactured by the company) 1.
5 parts of methyl ethyl ketone / toluene (weight ratio 1/1)
It is added while stirring with a mixer to prepare a coating liquid having a solid content of 15%, coated on the image-receiving layer in a dry weight of 2 g / m ^{2 and} dried, and heat-cured at 100 ° C. for 2 minutes for thermal transfer recording. An image receiving sheet was obtained.

[0033]

Comparative Example 1 An image receiving sheet for thermal transfer recording was obtained in the same manner as in Example 1 except that the intermediate layer was not provided.

[0034]

Comparative Example 2 As a coating liquid for the intermediate layer, thermally expandable hollow particles (trade name: Microsphere F-30, particle diameter 10/2
0 μm, Matsumoto Yushi-Seiyaku Co., Ltd.) 15 parts and titanium oxide powder (trade name: FA-55W, Furukawa Mining Co., Ltd.) 85 parts were replaced with composite thermoplastic resin hollow fine particles 100 parts in the same manner as in Example 1. This was carried out to obtain an image receiving sheet for thermal transfer recording.

With respect to the thus obtained three types of image receiving sheets for thermal transfer recording, a quality comparison test was conducted as follows.
That is, a blue heat sublimation dye (trade name: KST-B-71
4, manufactured by Nippon Kayaku Co., Ltd., 4 parts, polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 4
Parts of methyl ethyl ketone / toluene (weight ratio 1/1) 1
As an ink for forming a color material layer by dissolving in 100 parts, it is applied onto a polyester film having a thickness of 6 μm and heat-treated on the back surface so that the dry weight is 1 g / m ² , and the color material is transferred. Created a sheet.

Next, the coating surfaces of the color material transfer sheet and the image receiving sheet for thermal transfer recording are superposed, and heat is applied from the back surface of the color material transfer sheet by a thermal head (12 V, 4 to 16 mse).
Then, a thermal transfer recording image was formed on the image receiving layer surface of the image receiving sheet, and the recording density and image quality of each image receiving sheet and the recorded image were evaluated as follows, and the results are shown in Table 1.

[Evaluation] (Recording Density) Measurement was carried out with a Macbeth densitometer (RD-914) at five points with an applied pulse width of 4, 7, 10, 13, 16 ms. (Image quality) The image in the highlight part (7 ms) was observed with a 25x magnifying glass to evaluate dot reproducibility and dot dropout. (Evaluation Criteria) A: No dot dropout and good dot reproducibility. B: There are some missing dots, but there is practicality. C: Dot omission is conspicuous and there is a problem in practicality. D: Missing dots and poor reproducibility, no practicality.

[0038]

[Table 1]

[0039]

As is clear from the results of the table, the image-receiving sheets for thermal transfer recording obtained in the examples of the present invention have not only excellent recording sensitivity but also extremely clear and high color density recorded images, It was an image-receiving sheet for thermal transfer recording which was particularly excellent in image quality.

Claims (2)

[Claims] 1. A thermal transfer recording image-receiving sheet comprising a support and an image-receiving layer for receiving a transfer image from a color material transfer sheet, wherein the composite is surface-coated with an inorganic powder between the image-receiving layer and the support. An image-receiving sheet for thermal transfer recording, comprising an intermediate layer containing fine particles of a thermoplastic resin. 2. The image-receiving sheet for thermal transfer recording according to claim 1, wherein the thermoplastic resin fine particles are hollow fine particles.