JPS6227181A - Thermal transfer material and production thereof - Google Patents

Abstract

PURPOSE:To enable printing with high density and favorable sharpness to be performed even on a recording paper having poor surface smoothness, by a construction wherein a heat-fusible material in a thermally transferable ink layer forms two or more kinds of domains which are constituted respectively of different fine particles of heat-fusible resins. CONSTITUTION:The thermal transfer material 1 has the thermally transferable ink layer 3 comprising a heat-fusible material on a base 2 which is ordinarily in the form of a sheet. The ink layer 3 is constituted of, for example, two kinds of fine particles of heat-fusible resins - kind A and kind B - which respectively form two kinds of domains (each of the domains consists of a single kind of the fine particles). In producing the thermal transfer material, the heat- fusible ink layer is provided by applying a coating liquid comprising as a main ingredient a mixture of dispersed two or more kinds of fine particles of heat- fusible resins, and drying the coating liquid at a temperature lower than the lowermost one of softening temperatures of the fine resin particles.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a thermal transfer material that can provide a transferred recorded image with good print quality even on a recording medium with poor surface smoothness during thermal transfer recording. and its manufacturing method.

[Conventional technology]

In addition to the general features of thermal transfer recording methods, such as the equipment used being lightweight, compact, noiseless, and easy to operate and maintain, the thermal transfer recording method does not require color-forming processed paper; It has the feature of excellent image durability, 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 consisting of a colorant dispersed in a heat-melting binder is coated on a support, which is generally in the form of a sheet. 70 Thermal transferable ink layer is superimposed on the recording medium so that it is in contact with the recording medium, and heat is supplied from the support side with a thermal head to transfer the melted ink layer to the recording medium, thereby supplying heat onto the recording medium. A transfer recording image is formed according to the 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 smoothness is rather special, and normal paper has various degrees of unevenness due to the entanglement of m-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 only penetrates and adheres to the convex parts of the surface or the vicinity thereof, resulting in sharp edges of the printed image. If the image is missing or part of the image is missing, the print quality will deteriorate.

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, when the thickness of the transferable ink layer is increased, bleeding increases 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. The present invention was made in order to provide a heat-sensitive transfer material that can provide high-quality and sharp prints.

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 heat-sensitive transfer material provided by the present invention is a heat-sensitive transfer material having a heat-transferable ink layer containing a heat-melting material on a support, in which the heat-melting ink layer contains two or more types of heat-melting materials. It is characterized in that it forms domains, and each domain is composed of different types of heat-melting resin fine particles.

In addition, the method for producing the thermal transfer material of the present invention, which has been discovered as a novel method that can advantageously produce the thermal transfer material of the present invention having the above structure, includes the method of manufacturing the thermal transfer ink layer of two or more types. After applying a coating liquid containing a mixture of dispersions of different types of heat-melting resin fine particles as a main ingredient, the coating liquid is heated at a temperature lower than the lowest softening temperature among the softening temperatures of the group of hot-melting resin fine particles. It is characterized in that it is provided by drying.

[Detailed description and examples of the invention]

In the heat-sensitive transfer material of the present invention, the heat-fusible material forms two or more types of domains within the heat-transferable ink layer, and each domain is composed of different types of heat-fusible resin particles. The cohesive force can be greatly reduced compared to a homogeneous system. These two or more types of domains proceed to fuse and become homogenized in the pattern heating section, forming a recorded latent image with high cohesive force, and the adhesive force that acts as the adhesive force of the recorded latent image to the recording medium. can occur. In addition, since it is composed of two or more types of domains, and there are domains with different functions or physical properties, such as adhesive strength or cohesive force when heated, the state is such that each function or physical property is more easily expressed than in the case of a homogeneous system. be able to. In this way, in the thermal transfer ink layer, there is a large difference in cohesive force between the heat applied area (pattern heating area) and the non-heating area, so a clear recorded image can be obtained, and the recorded latent image can be formed in the pattern. By generating adhesive force to the recording medium, a transferred recorded image with good print quality can be formed even on a recording medium with poor surface smoothness.

The present invention will be explained in more detail below. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

FIG. 1 and FIG. 2 respectively show one part of the thermal transfer material of the present invention.
FIG. 3 is a schematic cross-sectional view in the thickness direction showing an example.

In the present invention, a domain refers to, in a heterogeneous system, a composition,
It refers to a region that can be distinguished from others based on physical properties, etc., and each domain is composed of a single or a plurality of thermofusible resin fine particles.

When the same elements are represented by the same reference numerals, the thermal transfer material 1 shown in FIGS.
have.

The thermal transferable ink layer 3 is composed of two types of heat-melting resin fine particles, for example, type A (hollow circle in the figure) and type B (solid black circle in the figure). single A
A domain is formed by the heat-melting resin fine particles of the seed and B type. In addition, in the example of FIG. 2, each of the plural A
A domain is formed by a high-order aggregate of the seed and B type heat-melting resin fine particles. Alternatively, the state may be such that domains of single particles and domains of aggregates coexist.

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.

The thermal transferable ink layer 3 may contain a coloring material as necessary, and 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 diameter is about 15 microns, and when using a thermal head, the surface of the support that comes into contact with the thermal head should be coated with silicone resin, fluorine resin, polyimide resin, epoxy resin, phenol resin, melamine resin, acrylic resin. The heat resistance of the support can be improved by providing a heat-resistant protective layer made of nitrocellulose, etc.
Alternatively, support materials that could not be used conventionally can also be used.

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 heat-melting resin fine particles are produced by emulsion polymerization, suspension/ffi
Methods using polymerization processes such as polymerization, methods of mechanically dispersing hot-melt resins using dispersants, etc., low mechanical crushing thereof,
Among those obtained by spray drying method, precipitation method, etc., the softening temperature of fine particles is 50°C to 160°C, preferably 60°C to
A temperature of 150°C is used. In addition, the softening temperature here is determined using a Shimadzu flow tester CFT-500 type.
This refers to the outflow starting temperature of a sample measured under the conditions of a load of 10 kg and a temperature increase rate of 2° C./min.

The average particle diameter of the heat-melting resin fine particles is 20 ILm or less (
~0.014m), and even less than 10 (~0.1gm
degree) is preferable.

If it exceeds 20 gm, it is too large and the particle size may be the same as the ink layer thickness. In this case, voids are likely to occur in the recorded latent image when the adjacent particles are fused together by heat application, resulting in poor transferability, which is undesirable.For this reason, the particle diameter and ink layer thickness may not be the same. Undesirable.

The ratio of the different types of heat-melting resin fine particles constituting the heat-transferable ink layer can be arbitrarily selected depending on the functions or physical properties exhibited by each particle, and is not particularly limited.

The layer thickness of the thermal transferable ink layer is 1 to 20 ILm, more preferably 2 to 20 ILm.
If the layer thickness of the thermally transferable ink layer, which is preferably 10 pm, is as thin as less than IILm, the film properties of the latent image formed by heat application and fine particles fusing together will be weakened.
If it exceeds gm, it is difficult to achieve uniform fusion of the fine particles throughout, which is not preferable.

The thermal transferable ink layer is prepared by appropriately selecting two or more types of fine particles from among the above-mentioned examples of heat-melting resin fine particles, mixing the fine particles with each other as appropriate, and uniformly distributing the fine particles on the support, and then adjusting the softening temperature of the fine particles. The layer can be formed by heating to the following temperature conditions and fixing it on the support, but after appropriately mixing and coating a fine particle dispersion, for example, a resin emulsion, it is necessary to A method in which the layer is formed by drying at a temperature lower than the lowest softening temperature to remove the dispersion medium is particularly preferable. You can keep it.

Colorants include carbon black, nigrosine dye,
Lamp black, Sudan black SM, First Yellow G, Benzidine Yellow, Hifmen) Yellow, Indo First Orange, Irgazine e Red, Paranitroaniline Red, Toluidine φ Red, Carmine F
B, Permanent Bordeaux FRR, Pigment No. Orange R, Resole Red 2G, Rake Left C,
Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant φ Green B, Phthalocyanine Green, Oil Yellow GG, Zapon-First Niro10 GG, Kayaset Y963, Kayaset YG, Sumiplast e Yellow 〇G, Zapon First Orange RR,
Oil Scarlet, Sumiblast Orange G, Orazole Brown G, Pomelo First Scarlet C
It is possible to use one or more of the known dyed Φ pigments such as G, Eisensbiron Ban Red/BEH, Oil Pink OF, Victoria Blue F4R, First Gen Blue 5007, Sudan Blue, and Oil Peacock Blue.

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 wide tape used in 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 explained in more detail with reference to Examples.

Example (Ink 1) Ink 1 having a solid content concentration of 25% was prepared by thoroughly stirring and mixing each component of the above formulation.

Coating 0.3g/m2 of additive silicone resin for release paper.
Using an applicator, apply Ink 1 on the side opposite to the heat-resistant protective layer of the 3.5 m polyester support with the dried heat-resistant protective layer provided, and evaporate the water at 60°C to form a layer with a thickness of 3p.
A heat-sensitive transfer material (I) was obtained by forming an ink layer of m.

Comparative example〈Ink? ) L Ink 2 having the above formulation was applied to the same support surface as in Example 1 using an applicator and dried while drying to form an ink layer with a layer thickness of 3 m to obtain a thermal transfer material (II).

Thermal transfer recording was performed on the thermal transfer materials (I) and (II) thus obtained with the following softness.

e Thermal head Thin film head 24-dot configuration 1 dot size O, L4 x 0.15mm Distance between dots 0., Q1
5+nnn Heating element resistance value 315Ω ・Applied voltage 13. , 2 V - Applied pulse width 1.1 m5ec - Recording paper: pound paper (Beck smoothness: 7 to 8 seconds) The printing and transfer properties were evaluated, and the results are shown in Table 1.

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

〔Effect of the invention〕

The thermal transfer material of the present invention can provide high-density and sharp prints not only on recording media with good surface smoothness, but also on recording media with poor surface smoothness. . 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 drawings]

FIG. 1 and FIG. 2 respectively show one part of the thermal transfer material of the present invention.
FIG. 3 is a schematic cross-sectional view in the thickness direction showing an example. 1φ-eyelid thermal transfer material 2 2...Support. 3Il...Thermal transferable ink layer. A, B-Φ- different types of heat-melting resin fine particles. Agent Patent Attorney Sekihei Yamashita Figure 1

Claims (2)

[Claims] (1) In a heat-sensitive transfer material having a heat-transferable ink layer containing a heat-fusible material on a support, the heat-fusible material of the heat-fusible ink layer forms two or more types of domains, and each domain is of different types. A heat-sensitive transfer material characterized by being composed of heat-melting resin fine particles. (2) A heat-transferable ink layer containing a heat-fusible material is provided on a support, and the heat-fusible material of the heat-transferable ink layer is 2
When producing a heat-sensitive transfer material in which more than one type of domains are formed and each domain is composed of different types of heat-melt resin fine particles, the heat-transferable ink layer is formed by two or more types of different types of heat-melt resin fine particles. After applying a coating liquid containing a mixture of the dispersion as a main ingredient, the coating liquid is dried at a temperature lower than the lowest softening temperature among the softening temperatures of the group of heat-fusible resin fine particles. Characteristic method for producing thermal transfer materials.