JPS6221582A - Thermal transfer material and production thereof - Google Patents

Abstract

PURPOSE:To provide a thermal transfer material enabling sharp printing with high density to be performed even on a recording medium having poor surface smoothness, by a method wherein the first ink layer is constituted of a homogeneous system comprising a heat-fusible material, and the second ink layer comprises fine particles of a heat-fusible resin and a non-particulate phase. CONSTITUTION:The first ink layer 3 and the second ink layer 4 comprising respective heat-fusible materials are provided on a sheet form base 2. The first ink layer 3 comprises a heat-fusible material forming a homogeneous system, for example, a non-particulate heat-fusible binder. The second ink layer 4 comprises domains constituted of fine particles A of a heat-fusible resin and a non-particulate phase B. At a patterwise heated part, mutual fusing and homogenization proceed, a latent record image having high cohesive force is formed, and an adhesive force functioning for adhesion of the latent record image to the recording medium is generated. Accordingly, because a large difference in cohesive force is generated between a heat-applied part and an unheated part in the second ink layer, clear record images can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is capable of producing transfer recorded images with good print quality even on recording media with poor surface smoothness during thermal transfer recording. This invention relates to a thermal transfer material and its manufacturing method.

[Conventional technology]

The thermal transfer recording method has the general features of the thermal transfer recording method, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability. It has the advantage of excellent intermittency of recorded images, and has been widely used recently.

This heat-sensitive transfer recording method uses a heat-sensitive transfer material in which a heat-transferable ink layer made of a coloring material dispersed in a heat-melting binder is coated on a support, which is generally in the form of a sheet. is superimposed on the recording medium so that its thermally transferable ink layer is in contact with the recording medium, and heat is applied from the support side by a thermal head to transfer the melted ink layer onto the recording medium, thereby applying heat to the recording medium -1x. A transferred recorded image is formed according to the supplied shape (pattern).

However, in the conventional thermal transfer recording method, the transfer recording performance, that is, the print quality, is greatly affected by the surface smoothness of the recording medium. Good printing is performed on recording media with high smoothness, but on recording media with low smoothness, In this case, there is a problem in that the print quality is significantly degraded. For this reason, paper with high surface smoothness is generally used as a recording medium, but paper with high surface smoothness is rather special, and normal paper has various degrees of unevenness due to the entanglement of fibers. Therefore, in the case of paper with large surface irregularities, the hot-melted ink cannot be transferred to the entire recording area of the paper during printing, but penetrates only to the convex parts of the surface or the vicinity thereof, resulting in the edges of the printed image. The image may not be sharp or part of the image may be missing, reducing print quality.

Conventionally, in order to obtain a recorded image of good print quality on such a recording medium with poor surface smoothness, for example, it is necessary to use a hot-melt binder with a low melt viscosity in at least the surface layer, or to use a thermally transferable binder. A method has been adopted based on the idea that by increasing the thickness of the ink layer, molten ink can faithfully adhere to or penetrate into the fine uneven structure of a recording medium such as paper. However, when a binder with a low melt viscosity is used, the ink layer becomes sticky even at a relatively low temperature, resulting in problems such as decreased storage stability and staining of non-printed areas of the recording medium, and also causes bleeding of transferred images. Furthermore, if the thickness of the transferable ink layer is increased, bleeding becomes larger and the amount of heat supplied from the thermal head also needs to be increased, resulting in a decrease in printing speed.

[Problems to be solved by the invention]

The present invention solves the conventional problems, maintains various thermal transfer performances, and improves density not only for recording media with good surface smoothness, but also for recording media with poor surface smoothness. This invention was made to provide a heat-sensitive transfer material that can print with high sharpness and sharpness.

The present invention has also been made to provide a novel method that can advantageously produce a thermal transfer material having the above-mentioned excellent characteristics.

[Means for solving problems]

That is, the thermal transfer material provided by the present invention has a first ink layer and a second ink layer each containing a heat-fusible material on a support, in order from the support side. The heat-fusible material of the first ink layer constitutes a homogeneous system, and the heat-fusible material of the second ink layer forms two or more types of domains, at least one of which is heat-fusible. It is composed of fine resin particles [and is characterized in that at least one other type of domain is composed of a non-particulate phase.

Further, in the method for manufacturing the thermal transfer material of the present invention, which has been discovered as a novel method that can advantageously manufacture the thermal transfer material of the present invention having the above structure, the second ink layer is heated to a softening temperature of After applying a coating liquid mainly consisting of a mixture of two or more types of heat-melting resin fine particle dispersions having different temperatures, the coating liquid is applied at a temperature between the lowest softening temperature and the highest softening temperature of the hot-melting resin fine particles. It is characterized in that it is provided by drying at a high temperature.

[Detailed description and examples of the invention]

In the thermal transfer material of the present invention, the heat-fusible material forms two kinds of domains in the second ink layer, so the cohesive force in the ink layer is greatly reduced compared to a homogeneous system. can be reduced. Coupled with the fact that at least one type of these two or more types of domains is composed of hot-melt resin fine particles, the fusion Φ homogenization progresses in the pattern heating section, resulting in a recorded latent image with high cohesive force. At the same time, it is possible to generate an adhesive force that acts as an adhesion force of the recording latent image to the recording medium. In this way, in the second ink layer, there is a large difference in cohesive force between the heat applied part (pattern heating part) and the non-heated part, which is a factor in obtaining a clear recorded image.

Further, the first ink layer is a homogeneous system of heat-fusible material, and has the function of regulating and suppressing the adhesion force to the support due to the adhesive force generated in the second ink layer when heat is applied.

In other words, the film strength changes in a pattern by applying heat.
The recorded latent image produces strong adhesive force to the recording medium and weak adhesive force to the support controlled by the first ink layer, resulting in transfer of the recorded latent image to the recording medium (formation of recorded image). ) has an extremely favorable power relationship. As a result, the thermal transfer material according to the present invention can form a recorded transfer image with good print quality even on a recording medium with poor surface smoothness.

Hereinafter, the present invention will be explained in detail. In the following description, "%" and "part" expressing product ratio are based on heavy standards unless otherwise specified.

FIG. 1 is a schematic cross-sectional view in the thickness direction showing one example of the thermal transfer material of the present invention.

In the present invention, a domain refers to, in a heterogeneous system, a composition,
An area that can be distinguished from others based on its physical properties.

The thermal transfer material 1 shown in FIG. 1 has a first ink layer 3 and a second ink layer 4 each containing a heat-melting material on a sheet-like support 2. The heat-sensitive transfer material 1 shown in FIG.

The first ink layer 3 is made of a heat-melting material that constitutes a homogeneous system:
11 For example, it is composed of a non-particulate heat-melting binder as a component.

In the second ink layer 4, one or more types of domains are formed by the thermofusible resin fine particles A and the non-particulate phase B, respectively. The heat-melting resin fine particles A may constitute a single domain, or a domain may be constituted by a high-order aggregate. Further, two or more types of domains I- may be constituted by different types of thermofusible resin fine particles A.

In this case, by changing the type of fine particles, domains with different functions or physical properties, such as hot adhesive strength or cohesive force, are formed, so that each function or physical property is easily expressed. Similarly, the non-particulate phase B may constitute two or more types of domains in a phase-separated state, for example.

Note that the term "thermofusibility" as used in the present invention means a property of melting and becoming liquid when heat is applied, or a property of softening by heat and exhibiting adhesive strength or adhesive strength.

At least one of the first ink layer 3 and the second ink layer 4
In addition to containing a coloring agent as necessary, each layer may also contain various additives such as a plasticizer and an oil agent.

As the support 2, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, polyphenylene sulfide, polyimide, cellophane, or parchment paper. , condenser paper, etc. can be suitably used. The thickness of the support should be 1 when considering a thermal head as a heat source during thermal transfer.
It is desirable that the thickness be about -15 microns. In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, acrylic resin, nitrocellulose, etc. is applied to the surface of the support that comes into contact with the thermal head. The heat resistance of the support can be improved by providing
Alternatively, support materials that could not be used conventionally can also be used.

Examples of the heat-melting binder that can be used in the first ink layer include carnauba wax, paraffin wax, Sasol wax, microcrystalline wax,
Waxes such as castor wax, stearic acid, palmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate.

Higher fatty acids such as zinc palmitate, methyl hydroxystearate, glycerol monohydroxystearate, or their metal salts, derivatives such as esters, polyamide resins, polyester resins, extremely high molecular acid epoxy resins, polyurethane resins, Vinyl resins, including acrylic resins (e.g. polymethyl methacrylate, polyacrylamide), vinyl acetate resins, polyvinylpyrrolidone, etc., polydiscontinued vinyl resins (e.g.
(vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, etc.), cellulose resins (for fM, methylcellulose, ethylcellulose, carboxycellulose, etc.), polyvinyl alcohol-based resins (e.g. polyvinyl alcohol, partially saponified polyvinyl alcohol) etc.), petroleum resins, rosin derivatives, coumaron-indene resins, terpene resins, novolac type phenolic resins,
Polystyrene resin, polyolefin resin (e.g.
polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, etc.), polyvinyl ether resins, polyethylene glycol resins, and elastomers,
Examples include natural rubber, styrene-butadiene rubber, and imprene rubber.

The softening temperature of the hot-melt binder is 40°C to 150°C
1 Preferably, the temperature is in the range of 60°C to 140°C. Further, it is preferable that the melt viscosity is 20,000 to 200,000 centiboise (rotational viscometer) at 150°C.

The thermofusible resin constituting the thermofusible resin fine particles includes:
Wax, polyolefin resins such as low-molecular polyethylene, polyamide resins, polyester resins, epoxy resins, polyurethane resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, petroleum resins,
Examples include phenolic resins, polystyrene resins, elastomers such as styrene-butadiene rubber, and isoprene rubber.

The thermofusible resin particles can be produced by polymerization processes such as emulsion polymerization and suspension polymerization, by mechanically dispersing the thermofusible resin using a dispersant, and by other methods such as mechanical crushing, spray drying, precipitation, etc. Among those obtained, the softening temperature of the fine particles is 50°C to 160°C, preferably 60°C to 15°C.
A temperature of 0°C is used. The softening temperature herein refers to the outflow start temperature of sample 1 measured using a Shimadzu flow tester CFT-500 under conditions of a load of 10 kg and a Jil temperature rate of 2°C.

The average particle diameter of the heat-melting resin fine particles is 20 gm or less (~
0.017z, m), and even less than 1O (~0.1p
(approximately Lm) is preferable.

If it exceeds 20 ILm, it is too large and the particle diameter may become the same as the ink layer thickness. In this case, voids are likely to occur in the recorded latent image when the particles are fused to adjacent particles by heat application, resulting in poor transferability, which is undesirable. Further, for this reason, it is not preferable that the particle diameter and the ink layer thickness are the same.

The ratio of the heat-fusible resin fine particles to the non-particulate phase constituting the second ink layer can be determined arbitrarily, but the ratio of the non-particulate phase to 100 parts of heavy acid of the hot-fusible resin fine particles 2～
It is preferably 400 parts by weight, more preferably 5 to 200 parts by weight.

The layer thickness of the first ink layer is 0.5-1OILm, the layer thickness of the second ink layer is 0.5-20pLm, furthermore 1-1OILm.
The total thickness of the first and second ink layers is preferably 2 to 25 #Lm. If the thickness of the second ink layer is thin, less than 0.5 μm, the film properties of the latent image formed by heat application and fine particles fusing together will be weak, and if it exceeds 2011 m, the overall This is not preferable because it is difficult to uniformly fuse the fine particles.

The first ink layer can be formed by hot melt coating, solvent coating, etc., using one or more of the heat-melting binders listed above, and using colorants, additives, etc. added as necessary. Can be painted.

The second ink layer contains, for example, the above-mentioned hot-melt resin fine particles or a dispersion thereof, the above-mentioned hot-melt binder or its solution or dispersion, and colorants, additives, etc. added as necessary. It is provided by applying a coating liquid by a conventional method and subjecting it to heat treatment if necessary. Note that in the second ink layer, the heat-melting resin fine particles remain in the ink layer in the form of particles, so when forming the ink layer, the coating liquid is usually heated at a temperature below the softening temperature of the hot-melting resin fine particles. It will be done.

Among these, in particular, two or more types of fine particles are selected from among the above-mentioned examples of heat-melting resin fine particles, and a dispersion of these particles, for example, a resin emulsion, is mixed and coated. Particularly preferred is a method in which the layer is formed by drying at a temperature between the temperature and the maximum softening temperature to remove the dispersion medium. In this case, coloring materials, additives, etc. added as necessary can be included in the dispersion or inside the fine particles. By this method.

Fine particles whose drying temperature is twice the softening temperature form a particulate phase, and fine particles whose drying temperature is below the softening temperature continue to exist as particulates.

Colorants include carbon black, nigrosine dye,
Lamp Black, Sudan Black SM, First Yellow G, Benzidine Yellow, Pigment Yellow, India First Orange, Irgazine Red, Valanitroaniline Red, Toluidine Red, Carmine F
B, Permanent Bordeaux FRR, Pigment Orange R, Lysol Fist Red 2G, Rake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Prilliant Green B.

Phthalocyanine Green, Oil Yellow GG, Zabon First Yellow CGG, Kayaset Y963, Kayaset YG, Sumiplast Yellow G, Zapon First Orange RR, Oil Scarlet, Sumiblast Orange G, Orazole Brown G, Pomelo First Scarlet CG, Aizens Viron Red φB
One or more types of known dyes and pigments such as EH, Oil Pink OP, Victoria Blue F4R, First Gen Blue 5007, Sudan Blue, and Oil Peacock Blue can be used.

These colorants may be used in at least one of the first ink layer and the second ink layer, but the second ink layer does not contain the colorant, and the colorant is only used in the first ink layer. If the second ink layer in contact with the recording medium does not contain a coloring material, the recorded image after transfer can be easily corrected in the event of erroneous printing.

The planar shape of the thermal transfer material of the present invention is not particularly limited, but it is generally used in the form of a typewriter ribbon or a 10-wide tape used for line printers. Further, for color recording, a heat-sensitive transfer material may be used in which heat-melting ink of several different tones is applied in stripes or blocks.

The thermal transfer recording method using the above thermal transfer material is not particularly different from a normal thermal transfer recording method, and a heat source such as a thermal head or a laser beam can be used as a heat source for thermal transfer recording.

EXAMPLES Hereinafter, the present invention will be further explained in JL terms by giving examples.

Example 1 <Ink 1> Ink 1 was prepared by dispersing carbon black by mixing each component of the above formulation in a sand mill for 30 minutes while heating it to 100°C. Ink 1 was hot-melt coated onto a 35 gm polyethylene terephthalate film (referred to as PET) using a Mayer bar to form a 1 μm thick first ink layer.

<Ink 2> (Hereinafter, the ratio is solid content ratio) Ink 2 was prepared by mixing each component of the above formulation. Ink 2 was applied onto the previously provided first ink layer using an applicator and dried at 80° C. to form a second ink layer with a layer thickness of 3 pLm to obtain a thermal transfer material (I).

In this second ink layer, fine particles of low molecular weight polyethylene oxide were confirmed by microscopic observation.

Example 2 Ink 3 was prepared by mixing each component of the formula E with -L of the first ink layer provided on PH7 obtained in Example 1. Ink 3 is applied using an applicator on the previously provided first ink layer, dried at 70°C to form a second ink layer with a layer thickness of 3#Lm, and the thermal transfer material (II) is applied. Obtained.

The presence of wax particles in this second ink layer was confirmed by microscopic observation.

Comparative Example On -L of the first ink layer provided on the 3y5gmPET obtained in Example 1, (Ink 4) Ink 4 of the above formulation was applied with an applicator and dried.
A second ink layer with a layer thickness of 3 JLm was formed, and a thermal transfer material (
I II I) was obtained.

Thermal transfer materials (I) and (I' I
), (III) were thermally transferred and recorded using the following properties.

i Thermal head Thin film head 24 dot configuration 1 dot size 0.14XO, 15mm Distance between dots 0.015
mm ・Heating element resistance value 315Ω ・Applied voltage 13.2V Applied pulse width 1.1m5ec ・Recording paper Pound paper (Beck purity 7-8 seconds) Printing and transferability were evaluated, and the results are shown in Table 1. .

Table 1: Using the thermal transfer material of the present invention: 1. As shown in the table above, even on paper with low smoothness, high-quality prints with good sharpness and transferability and high print density can be obtained.

〔Effect of the invention〕

The thermal transfer material of the present invention can print with high density and excellent IT separation not only on recording media with good surface smoothness, but also on recording media with poor surface smoothness. be able to. Furthermore, the method for producing a heat-sensitive transfer material of the present invention is a novel method, and it is possible to advantageously produce a heat-sensitive transfer material having such excellent characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view in the thickness direction showing one example of the thermal transfer material of the present invention. l...Thermal transfer material. 2. Association φ support body. 3--First ink layer. 4...Second ink layer. A...Thermofusible resin fine particles. B--Non-particulate phase. Agent Patent Attorney Seki Yamashita Figure 1-I;Achi-

Claims (2)

[Claims] (1) A thermal transfer material having a first ink layer and a second ink layer each containing a heat-fusible material on a support, in order from the support side, wherein the heat-fusibility of the first ink layer The materials constitute a homogeneous system,
The thermofusible material of the second ink layer forms two or more types of domains, at least one of which is composed of thermofusible resin fine particles, and at least one other domain is composed of a non-particulate phase. A heat-sensitive transfer material comprising: (2) A first ink layer and a second ink layer each containing a heat-fusible material are provided on the support in order from the support side, and the heat-fusible material of the first ink layer is uniform. and the thermofusible material of the second ink layer forms two or more types of domains, at least one of which is composed of thermofusible resin fine particles and at least one other domain. When manufacturing a thermal transfer material in which the second ink layer is composed of a non-particulate phase, the second ink layer is coated with a mixture of two or more types of heat-melting resin fine particle dispersions each having a different softening temperature. A method for producing a heat-sensitive transfer material, which comprises applying a coating solution and then drying the coating solution at a temperature between the lowest softening temperature and the highest softening temperature of the heat-fusible resin fine particles.