JPS6398491A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To print with high density and favorable sharpness even on a recording material poor in surface smoothnes, by a construction wherein heat-fusible materials in a thermally transferrable ink layer constitute at least two kinds of domains, and at least one kind of the domains are constituted of colored heat-fusible resin particulates. CONSTITUTION:A thermal transfer material 1 comprises a thermally transferrable ink layer 3 comprising a heat-fusible materials, on a sheet-shaped base 2. The ink layer 3 has at least one kind each of domains constituted respectively of colored heat-fusible resin particulates A and a non-granular phase B. A plastic film having a relatively favorable heat resistance, cellophane or a parchment paper, a condenser paper or the like can be suitably used as the base 2. The thickness of the base is preferably about 1-15mum where a thermal head is expected to be used as a heat source. Since a large difference in cohesive force is generated between a heated part and a non-heated part in the thermally transferrable ink layer, a clear recorded image can be obtained, and since a latent image of the record produces an adhesive force for adhesion to a recording material imagewise, favorable printing can be achieved even on a recording material poor in surface smoothness.

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. Regarding.

[Prior art] In addition to the general features of the thermal transfer recording method, such as the equipment used is lightweight, compact, noiseless, and easy to operate and maintain, the thermal transfer recording method does not require colored processed paper. It also has the feature of excellent durability 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 colorant dispersed in a heat-melting binder is coated on a support, which is generally in the form of a sheet.
This thermal transfer material is superimposed on a recording medium so that its thermal transferable ink layer is in contact with the recording medium, and heat is supplied from the support side by a thermal head to transfer the melted ink layer onto the recording medium. Heat supply shape (pattern)
It forms a transferred recorded image according to the

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 fibers. Therefore, in the case of paper with large surface irregularities, the hot melted ink during printing cannot be transferred to the entire recording area of the paper, but only penetrates and adheres to the convex parts of the surface or the vicinity thereof. The print quality may deteriorate if the image is not properly printed or part of the image is missing.

Conventionally, in order to obtain recorded images of good print quality on such recording media with poor surface smoothness, it has been necessary, for example, 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 a decrease in storage stability, staining of non-printing areas of the recording medium, and smearing of transferred images. . Furthermore, if the thickness of the thermally 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.

Generally, methods for increasing print density include increasing the thickness of the colored ink layer and increasing the amount of coloring components added to the ink layer. However, if the layer thickness is increased or the amount added is increased, the cohesive force of the ink layer will decrease when heat is applied because the pigments, dyes, etc. that become the coloring components themselves do not have heat meltability, and the transferability may decrease. Printing becomes impossible. Furthermore, when the amount of non-thermofusible material added to the ink layer is increased in this way, even higher applied energy is required to obtain the original transferability.

[Problems to be Solved by the Invention] The present invention solves the conventional problems and is applicable not only to recording media with good surface smoothness while maintaining various thermal transfer performances, but also to recording media with good surface smoothness. The purpose of this invention is to provide a thermal transfer material that can print with high density and sharpness even on recording media that do not have a high density.

[Means for Solving the Problems] That is, the heat-sensitive transfer material provided by the present invention has a heat-transferable ink layer containing a heat-melting material on a support. The thermofusible material forms two or more types of domains, and at least one of the domains is composed of colored thermofusible resin fine particles.

[Detailed Description and Examples of the Invention] In the heat-sensitive transfer material of the present invention, since the heat-fusible materials form two or more types of domains in the heat-transferable ink layer, the cohesive force in the ink layer is reduced. It can be made much smaller than a uniform system. Coupled with the fact that these two or more types of domains are composed of at least one type of colored thermofusible resin fine particles, fusion and homogenization progress in the pattern heating section, resulting in a high cohesive force. It is possible to form a recorded latent image and to generate adhesive force that acts as an adhesive force of the recorded latent image to the recording medium. 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 shaped like a 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.

In addition, since colored hot-melt resin fine particles are used as the coloring component, even when the coloring component is increased to increase the concentration, the particle nature is maintained, and furthermore, when heat is applied, agglomeration between the heated part and the non-heated part is prevented. It is possible to maintain the difference in power. This makes it possible to form a transferred recorded image with high print density and good print quality without increasing the applied voltage.

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 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.

In the present invention, two or more types of domains are selected from one or more types of domains composed of heat-soluble resin particles and one or more types of domains composed of non-particulate phases. An appropriate number of domains are selected. In the present invention, when selecting this domain, it is necessary that at least one type of domain is constituted by colored hot-melt resin fine particles.

The thermal transfer material 1 shown in FIG.
have.

In the thermal transferable ink layer 3, the colored heat-melting resin fine particles A and the non-particulate phase B each form one or more types of "-domains."

The colored thermofusible resin fine particles A may constitute a single domain, or a domain may be constituted by a highly ordered aggregate. In addition, at least one type of domain is composed of colored thermofusible resin fine particles, and two or more types of 1 to 2 are composed of different types of colored thermofusible resin fine particles and non-colored thermofusible resin fine particles A. You can also configure the main. 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 "thermal meltability" 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.

As the support 2, conventionally known films and papers can be used as they are, such as polyester, polycarbonate, polyacetyl cellulose, polyphenylene sulfide 1, polyimide, and other relatively heat-resistant plastic films. , cellophane, parchment paper, condenser paper, etc. can be suitably used. The thickness of the support is preferably about 1 to 15 microns when considering the thermal spatula 1 as a heat source during thermal transfer. In addition, when using a thermal head, the surface of the support that comes into contact with the thermal head may be made of a heat-resistant material such as silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, acrylic resin, cellulose, etc. By providing a protective layer, the heat resistance of the support can be improved, or it is possible to use a support material that could not be used conventionally.

In the heat-transferable ink layer, heat-melting materials that can be used to constitute the heat-melting resin fine particles or non-particulate phase that form the domains include carnauba wax, paraffin wax, Sasol wax, and microcrystalline. Waxes, waxes such as castor wax, stearic acid, valmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, zinc valmitate, methylhydroquine stearate, glycerol monohydroxystearate, Higher fatty acids such as or their metal salts, derivatives such as esters, polyamide resins, polyamide resins, epoxy resins, polyurethane resins, acrylic resins (e.g. polymethyl methacrylate, polyacrylamide), polyvinyl acetate resins , vinyl resins including polyvinylpyrrolidone, polyvinyl chloride resins (e.g. vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinyl acetate copolymer, etc.), cellulose resins (e.g. methyl cellulose, ethyl cellulose, carboxy cellulose, etc.), polyvinyl alcohol resins (e.g. polyvinyl alcohol, partially saponified polyvinyl alcohol, etc.), petroleum resins, rosin derivatives, coumaron-indene resins, terpene resins, novolac type phenolic resins, polystyrene resins, polyolefin resins (
For example, polyethylene, polypropylene, boriztene,
(ethylene-vinyl acetate copolymer, etc.), polyvinyl ether resins, polyethylene glycol resins, elastomers, natural rubber, styrene-butadiene rubber, imprene rubber, and the like.

The softening temperature of the thermofusible material ranges from 40'C to 1500C, preferably from 60C to 140C.

In addition, the melt viscosity is 2 centivoise to 2 at 150°C.
It is preferable that it exhibits 00,000 centivoise (rotational viscometer).

Among these thermofusible materials, suitable thermofusible materials constituting the thermofusible resin particles include polyolefin resins such as Wanx, low molecular weight polyethylene, polyamide resins, polyester resins, epoxy resins, and polyurethane resins. resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, petroleum resins, phenolic resins,
Examples include elastomers such as polystyrene resin, styrene-butadiene rubber, and isoprene rubber.

The thermofusible resin fine particles can be produced by polymerization processes such as emulsion polymerization and suspension polymerization, by mechanically dispersing the thermofusible resin using a dispersant, etc., by low-mechanical pulverization, by the spray F-lying method, and by the precipitation method. 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 the sample measured using a Shimadzu flow tester CFT-500 under conditions of a load of 10 kg and a temperature increase rate of 2°C/min.

Colored thermofusible resin particles can be obtained by suspension polymerization, for example, by dissolving or dispersing coloring agents such as dyes and pigments in advance and subjecting them to suspension polymerization of colored monomers, or by using colored thermofusible resin particles. It can be obtained by a method such as mechanical crushing. The coloring materials used in this case are 1. Carbon black, Nigrosine dye, Lamp black, Sutan black SM, First Yellow G, Benzidine Yellow, Pigment Yellow, Indo First Orange,
Irgazine red, paranitroaniline red,
Toluidine Red, Carmine FB, Permanent Bordeaux FRB, Pigment Orange R, Lysol Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue, Pigment Blue, Prilliant Green 'N B, Phthalocyanine Green, Oil Yellow GG, f Hon First Yellow CGG, Kaya Set Y963. Kayaset YG, Sumi Blast Yellow G, Zapon Fast Orange RR, Oil Scarlet, Sumi Blast Orange G, Orazole Brown G, Pomelo Firth 1~Scarlet CG, Eisensubiron Red BEH, Oil Pink OP, Victoria Blue F4R, First Gen Blue 5007,
One or more known dyes and pigments such as Sudan Blue and Oil Peacock Blue can be used.

The average particle diameter of the hot-melt resin fine particles and the colored hot-melt resin fine particles is preferably 20 JLm or less (about 0.01 JLm), and more preferably 10 JLm or less (about 0.1 JLm). If it exceeds 207 zm, it is too large, so it may be useful if the particle diameter is the same as the ink layer thickness. In this case, when the particles are fused to adjacent particles by heat application, a bond is likely to be formed in the recorded latent image, resulting in poor transferability, which is undesirable. Further, for this reason, it is not preferable that the particle diameter and the ink layer thickness be the same.

Although the ratio of the colored or non-colored heat-melting resin fine particles to the non-particulate phase constituting the domains of the heat-transferable ink layer shown in FIG. 1 can be determined arbitrarily, the heat-melting resin fine particles 100 The amount of the non-particulate phase is preferably 2 to 400 parts by weight, more preferably 5 to 200 parts by weight.

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-mentioned 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 1 <Ink 1> Ink 1 having a solid content concentration of 25% was prepared by thoroughly stirring and mixing each component of the above formulation.

The colored wax emulsion was obtained as follows.

The above mixture was heated to 100°C, and the colored dispersion dispersed by an attritor was emulsified in water to form an emulsion with a solid content of 20% and an average particle size of 2 m.

Coating 0.3g/m2 of additive silicone resin for release paper.
Apply the ink IZe using an applicator onto the side opposite to the heat-resistant protective layer of a 3.5 μm polyethylene terephthalate film (hereinafter referred to as PET) that has been dried and provided with a heat-resistant protective layer.
lf cloth, water was evaporated at 60° C. to form an ink layer with a thickness of 5 μm, and a thermal transfer material (1) roughly shown in FIG. 1 was obtained.

Example 2 <Ink 2> (The above ratios are solid content ratios) The components of the above formulation were mixed to prepare Ink 1 with a solid content concentration of 25%. Note that the colored wax emulsion was obtained in the same manner as in Example 1. Ink 2 was applied using an applicator on the surface of the same PET opposite to the heat-resistant protective layer as in Example 1, and dried at 70°C to form an ink layer with a layer thickness of 5 gm. A thermal transfer material (n) shown below was obtained.

This ink layer was confirmed by microscopic observation to be fine particles of low molecular weight polyethylene oxide.

Comparative Example 1 <Ink 3> -1- Ink 3 having the formulation described above was applied onto the same support surface as in Example 1 using an applicator and dried to form an ink layer consisting of a single non-particulate layer with a layer thickness of 3 pm. Thermal transfer material (II
I) was obtained.

Thermal transfer material (I) (IT) (m) obtained in this way
Thermal transfer recording was performed under the following conditions.

・Thermal head Thin film head 24 totes configuration 1 dot size 0.14x 0.15mm distance between dots
[1,01511℃m・Heating element resistance value 31
5Ω ・Applied voltage 13.2V ・Applied pulse width 1.1 m5ec ・Recording paper Bond paper (Beck smoothness 7 to 8 seconds) Printing and transfer properties were evaluated, and the results are shown in Table 1.

Table 1: As shown in the table above, when the thermal transfer material of the present invention is used, it is possible to obtain high-quality printing with good sharpness and transferability even on paper with low smoothness, and with higher print density than conventional materials. can get.

[Effects of the Invention] The thermal transfer material of the present invention can provide sharp prints not only on recording media with good surface smoothness but also on recording media with poor surface smoothness. . Even when the coloring component is increased to increase the density, it is possible to provide high-quality prints with high print density without increasing the applied voltage.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view in the thickness direction showing one example of the structure of the thermal transfer material of the present invention. L...Thermal transfer material, 2...Support, 3...Thermal transferable ink layer, A...Colored thermofusible resin fine particles, B-...Non-particulate phase. Figure 1

Claims (1)

[Claims] 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 at least one of the domains is colored. A heat-sensitive transfer material characterized in that it is composed of fine heat-melting resin particles.