JPH01269590A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To enable a transferred image free of broken image parts and having favorable sharpness to be obtained even on a recording material low in surface smoothness, by providing a first ink layer, a specified second ink layer and a third ink layer on a base, in that order from the base side. CONSTITUTION:A thermal transfer recording material 1 comprises a first ink layer 3, a second ink layer 4 and a third ink layer 5 provided on a sheet-shaped base 2. The first ink layer 3 is provided for easy release of the second ink layer 4 from the base 2 at the time of heating to ensure favorable transferring. The second ink layer 4 comprises at least heat-fusible resin particulates, a water-soluble resin and a coloring agent. Particularly preferable examples of the water-soluble resin are polyvinyl pyrrolidone and polyvinyl alcohol. The water-soluble resin preferably has a weight average molecular weight of 12000-1500000. A heat-fusible material for the particulates may be, for example, a wax or a polyolefin resin such as a low molecular weight polyethylene. The third ink layer, which is adhered to a recording material when being heated, preferably comprises a resin-based heat-fusible material in an amount of 50-100%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer material used for thermal transfer recording.

[Conventional technology]

In addition to the general characteristics of thermal recording, such as the equipment used for thermal transfer recording being lightweight, compact, noiseless, and excellent in operability and maintainability, thermal transfer recording does not require colored processed paper, and the durability of the recorded image is improved. It has the characteristic of being excellent in sex,
Recently used method.

In such thermal transfer recording, when a wax-based heat-melting material is used for the heat-transferable ink layer of the heat-sensitive transfer material, the ink layer is completely melted by heat application, so the cohesive force of the heat-transferable ink layer is extremely low. There is a problem that it becomes small and the characters tend to be distorted.

In addition, wax-based thermal transfer ink layers have poor print abrasion resistance, and furthermore, when the surface smoothness of the recording medium is low, it is necessary to bring the thermal transfer ink layer into contact with the concave and convex portions of the surface of the recording medium. The thermally transferable ink layer is transferred only to the convex portions of the surface (so-called transfer defects). For this reason, printing quality is significantly degraded.

Therefore, for recording materials with low surface smoothness, the ink layer is placed in a state where the convex portions on the surface of the recording material are just bridged, and the concave portions of the recording material are covered. One possibility is to transfer the ink layer. To achieve this, a thermally transferable ink layer that exhibits tackiness when thermal energy is applied, but does not completely melt into a low-viscosity liquid, has high cohesive strength and appropriate flexibility, is used as a support. It needs to be placed on top.

In order to form such an ink layer, it is preferable that the ink layer is made of a heat-melting material containing resin as a main component.

If a resin-based thermal transfer ink layer is used, problems with crooked characters and scratch resistance will be eliminated, and sufficient cohesive force for cross-linking will be obtained.

[Problem that the invention seeks to solve]

However, when using a resin-based thermal transfer ink layer,
The border between the heating section and the non-heating section cannot be cut cleanly (the edges of the print may become wavy, resulting in poor print quality (so-called poor cutting).Also, there may be insufficient adhesion to the recording medium. In order to soften and melt the material until it exerts its power, it is necessary to input a large amount of thermal energy, which is undesirable because it shortens the life of the thermal printing head.

In order to prevent the thermal transfer ink layer from breaking, it is necessary that there be a large difference in cohesion between the heated and non-heated parts of the ink layer.However, hot melt coating or solvent coating The formed film-like ink layer has a strong cohesive force (becomes
It is difficult to maintain a large difference in cohesive force between the heated section and the non-heated section.

Therefore, the thermal transfer ink layer is composed of fine particles of heat-fusible material, and in the non-heating part, the fusion of the fine particles is suppressed, and in the heating part, the fusion of the particles progresses and the cohesive force increases.Thermal transfer material has been proposed.

However, there is a desire for a high quality thermal transfer material with even better printing quality.

The present invention has been made in view of the above-mentioned circumstances, and is applicable not only to recording media with good surface smoothness, but also to recording media with low surface smoothness, while maintaining various thermal transfer performances. It is an object of the present invention to provide a heat-sensitive transfer material that is free from transfer defects and can provide a well-defined transferred image.

[Means for solving problems]

The heat-sensitive transfer material of the present invention has a first ink layer, a second ink layer, and a third ink layer formed on a support in order from the support side, and the second ink layer is composed of heat-fusible resin fine particles. and a water-soluble resin, and the water-soluble resin has a number average molecular weight of 12,000 or more.

Hereinafter, the present invention will be described in detail with reference to the drawings as necessary. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

The thermal transfer material 1 of the present invention has a thermal transfer ink layer composed of at least a first ink layer 3, a second ink layer 4, and a third ink layer 5 on a sheet-like support 2, as shown in FIG. has.

The first ink layer 3 on the support 2 side is for easily releasing the second ink layer 4 from the support 2 during heating to obtain good transfer, and ideally the cohesive force during heating is 0. A material that satisfies the following is preferably used.

The material used for the ink layer 4 is preferably mainly wax, such as spermaceti wax, beeswax, lanolin, carnauba wax, and candelilla wax.

Natural waxes such as monk wax and ceresin wax, petroleum waxes such as paraffin wax and microcrystalline wax, oxidized waxes, ester waxes, and low molecular weight polyethylene.

Synthetic waxes such as Fischer-Tropsch wax,
Lauric acid, myristic acid, palmitic acid.

The main ingredients are higher fatty acids such as stearic acid and behenic acid, higher alcohols such as stearyl alcohol and behenyl alcohol, esters such as sucrose fatty acid ester, sorbitan fatty acid ester, amides such as oleylamide, and polyethylene glycol. is preferred. In particular, it is preferable to use polyethylene oxide as the main component. The number average molecular weight of the polyethylene oxide used in the first ink layer 3 is preferably 800 to 6,500, more preferably 1,
000 to 3,000 is preferable, more preferably 1,300 to 2
,500 is preferred.

If the number average molecular weight of the oxidized polyethylene is less than 800, the softening point of the first ink layer 3 will be low, and when stored at high temperatures, blocking etc. will easily occur. On the other hand, if the number average molecular weight is greater than 6,500, the degree of crystallinity increases, so that good adhesion to the support may not be obtained or the softening temperature may become too high. If the softening temperature is too high (if the softening temperature is too high, the energy applied by a normal thermal head will not be enough heat, the melted state of the first ink layer will be insufficient, and the transferability will deteriorate. In the present invention, the number average molecular weight of polyethylene oxide is VPO (VaporPr
essure Osmometery Method
d) is the value measured by the method.

The thickness of the first ink layer 3 is preferably 0.01 to 5 μm,
Furthermore, 0.1-2.5 micrometers is preferable. In addition, in order to control the adhesion between the support and the second ink layer 4, the first
For example, a polar material such as an acrylic resin or a vinyl acetate resin, or a non-polar material such as a wax may be added to the ink layer 3 in an amount of 50% or less, more preferably 30% or less, based on the first ink layer 3. Further, the first ink layer 3 may contain a colorant or a filler, but it is preferable not to add too much in order to obtain good adhesion to the support when not heated.

The first ink layer 3 may be a layer made of the above-mentioned materials in the form of a film, but it may also be formed from the above-mentioned materials in the form of fine particles and composed of these fine particles.

When the first ink layer 3 is composed of fine particles, the average particle size of the fine particles is preferably in the range of 0.01 to 5 μm, more preferably 0.1 to 2.5 μm.

The second ink layer 4 is composed of at least heat-melting resin particles, a water-soluble resin, and a colorant. When the second ink layer 4 contains the water-soluble resin, the water-soluble resin provides a protective film effect on the surface of the heat-melting resin fine particles, thereby preventing the fine particles from fusing together during the production of the heat-sensitive transfer material. I can do it. However, once heated, the heat-fusible resin fine particles are fused and homogenized, and a recorded image with high cohesive force is formed in the ink layer. Therefore, there is a large difference in cohesive force between the heated and unheated parts of the thermally transferable ink layer, and a sharp and clear recorded image can be obtained.

Examples of the water-soluble resin contained in the second ink layer 4 include celluloses such as methylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose, polyvinylpyrrolidone, methylvinyl ether-maleic anhydride copolymer, polyacrylamide, polyethylene oxide, polyvinyl alcohol, Examples include sodium polyacrylate. Among these, polyvinylpyrrolidone and polyvinyl alcohol are particularly preferred.

The weight average molecular weight of the water-soluble resin is preferably in the range of 12,000 to 1.5 million, more preferably 13,000 to 1.3 million. If the weight average molecular weight of the water-soluble resin is less than 12,000, the water-soluble resin will be thermally softened during the production of the heat-sensitive transfer material, reducing the protective film effect and causing resin fine particles to fuse together even in a non-heated state. On the other hand, if the weight average molecular weight of the water-soluble resin is greater than 1.5 million, it will be difficult for the heat-melting resin fine particles to efficiently fuse together during heating. Furthermore,
If the weight average molecular weight of the water-soluble resin is too large, the viscosity of the coating liquid for the second ink layer 4 will be high (and uneven coating will easily occur when forming the second ink layer 4. The weight average molecular weight of the resin is a value measured by a light scattering method.

Moreover, it is preferable that the glass transition temperature of the water-soluble resin is 60° C. or higher. The glass transition temperature of water-soluble resin is 60
If the temperature is lower than 0.degree. C., the heat softening of the water-soluble resin becomes large, and the protective film effect of the water-soluble resin is weakened during the production of a heat-sensitive transfer material, making it easy for resin particles to fuse together.

In addition, if the glass transition point of the water-soluble resin is high, it will be good in terms of cutting (but it will be inferior in terms of abrasion resistance).

For this reason, the glass transition point of the water-soluble resin is preferably 160°C or lower.

The content of the water-soluble resin in the second ink layer is preferably 0.1 to 50% in terms of solid content, and more preferably 0.5 to 35%. If the water-soluble resin content is less than 0.1%, it will be difficult to obtain the effect of containing the water-soluble resin, and conversely, if it is more than 50%, the water-soluble resin will fill in between the hot-melt resin particles. This causes fine particles to be firmly connected to each other, resulting in a high cohesive force.

The thermofusible materials used for the thermofusible resin particles constituting the second ink layer 4 include wax, polyolefin resins such as low-molecular polyethylene, polyamide resins, polyester resins, epoxy resins, polyurethane resins, Acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin9 Petroleum resin, phenolic resin, polystyrene resin.

Examples include elastomers such as styrene-butadiene rubber and isoprene rubber. Among these materials, examples of materials that exhibit remarkable effects of the added water-soluble resin include polyurethane resins, acrylic resins, polyvinyl acetate resin elastomers, and the like.

The thermofusible resin particles can be obtained 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, and precipitation methods. 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.

Note that the softening temperature referred to here is the temperature measured by Shimadzu Flow Tester CF.
Using T-500 type, load 10Kg, temperature increase rate 2'
This refers to the temperature at which the sample begins to flow out, measured under conditions of C/min.

The average particle diameter of the heat-melting resin particles is 0.01-10 μm
is preferable, and more preferably 091 to 4 μm.

The amount of the colorant contained in the second ink layer 4 is preferably 1 to 80% based on the second ink layer 4. Examples of the coloring agent contained include carbon black, nigrosine dye, lamp black, Sudan Black SM, and Fast Yellow G.
, Benzidine Niro, Pigment Yellow, India First Melengi, Irgazine Red, Valanitroaniline L Knot, Toluidine Red, Carmine F
B. Permanent Bordeaux FRR.

Pigment Orange R, Lysole Red 2G.

Rake φ Red C, Rhodamine FB, Rhodamine B
Lake, Methyl Skewer Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon Fast Yellow CGG, Kayaset Y963.
Kayaset YG, Sumiplast Yellow GG, Zapon
First Orange RR, Oil Scarlet, Sumiplast Orange G, Orazole Brown G, Pomelo First Scarlet CG.

Anzensbiron Red BEH, Oil Pink OP
, Victoria Blue F4R, First Gen Blue 50
One or more known dyes and pigments such as 07, Sudan Blue, and Oil Peacock Blue can be used.

The thickness of the Tsukiji ink layer 4 is preferably 0.1 to 10μ, more preferably 0.2 to 4μ. In addition, the second ink layer 4
may be separated into several layers as long as the conditions explained above are satisfied.

The third ink layer 5 is a layer that adheres to the recording medium by heating, and preferably contains 50 to 100% or more of a resin-based thermofusible material. By doing so, sufficient bridges can be formed between the convex portions on the surface of the recording medium, and a transferred recorded image with no character displacement and excellent scratch resistance can be obtained.

The resin-based heat-melting materials contained in the third ink layer 5 include polyolefin resin, polyamide resin, water-insoluble polyester resin, epoxy resin, polyurethane resin, polyacrylic resin, and polyvinyl chloride. based resin, cellulose based resin.

Polyvinyl alcohol resin 9 Right Oil-based resin, phenol-based resin, polystyrene-based resin, vinyl acetate-based resin, etc. are used.

The third ink layer 5 may include natural waxes such as spermaceti wax, beeswax, lanolin, carnauba wax, candelilla wax, monk wax, and ceresin wax in addition to resin-based heat-melting materials.

Petroleum waxes such as paraffin wax and microcrystalline wax, oxidized waxes, ester waxes,
Synthetic waxes such as Fischer-Tropsch wax,
Lauric acid, myristic acid.

Higher fatty acids such as valmitic acid, stearic acid, behenic acid, higher alcohols such as stearyl alcohol and behenyl alcohol, esters such as sucrose fatty acid ester, sorbitan fatty acid ester, amides such as oleylamide, natural rubber, styrene butadiene rubber,
Isoprene rubber.

Elastomers such as chloroprene rubber, polyisobutylene, polybutene, plasticizers, dispersants, oils such as mineral oil and vegetable oil, and fillers (for example, fine metal powders, fine inorganic powders, metal oxides, etc.) may be mixed as appropriate. I don't mind.

The thickness of the third ink layer 5 is 0.1 to 10 μm, more preferably 0.2 μm.
~4μ is preferred. The third ink layer 5 may be a layer made of the above-mentioned heat-fusible material formed into a film shape, but it may also be formed from the above-mentioned heat-fusible material in the form of fine particles and constituted by these fine particles. When the third ink layer 5 is composed of fine particles, the average particle diameter of the fine particles is preferably 0.01 to 10 μm, more preferably 0.1 to 4 μm.

Further, the third ink layer 5 may contain a colorant, but if the content of the colorant is too large, it becomes difficult for the third ink layer 5 to adhere to the recording medium. When layer 5 contains a colorant, the amount of the colorant is preferably 20% or less.

The total thickness of the entire thermal transferable ink layer is 0.3 to 20 μm.
It is preferably in the range of m, more preferably from 0.5 to
8 μm is good.

As the support 2, conventionally known films and papers can be used as they are, such as polyester, polycarbonate, and triacetylcellulose.

Plastic films with relatively good heat resistance such as polyphenylene sulfide and polyimide, cellophane or parchment paper, and condenser paper are preferably used. The thickness of the support is preferably about 1 to 15 microns when a thermal head is used as a heat source during thermal transfer, but when a heat source such as a laser beam that can selectively heat the thermal transfer ink layer is used, for example. There are no particular restrictions. 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. By providing this, the heat resistance of the support can be improved, or a support material that could not be used conventionally can be used.

The heat-sensitive thermal transfer material of the present invention may be prepared by mixing and stirring the materials of each layer to prepare a coating liquid, and applying this coating liquid onto a support using an applicator or the like.

The planar shape of the thermal transfer material 1 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, it is also possible to use a heat-sensitive transfer material in which heat-melting inks of several different tones are 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 thermal head, laser light, etc. can be used as a heat source for thermal transfer recording.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A 25% solution (coating solution 1) of polyethylene oxide emulsion obtained by emulsifying the above formulation 1 under pressure and heat was coated with a silicone resin for release paper to a thickness of 0.3 μm on the side opposite to the ink-applied surface. Using an applicator, the film was coated onto a polyethylene terephthalate film with a thickness of 6 μm on which a heat-resistant protective layer was formed and dried at 60°C for 3 minutes to give a layer thickness of 1.0 μm.
A first ink layer 3 was provided.

Further, the following formulations 2 and 3 were uniformly mixed using a propeller type stirrer to obtain coating liquids 2 and 3.

This coating liquid 2 is applied onto the first ink layer 3 using an applicator, and dried with hot air at 60°C for 1 minute.
A second ink layer 4 having a layer thickness of 1.5 μm was provided.

Further, the coating liquid 3 was applied onto the second ink layer 4 using an applicator, and dried with hot air at 50° C. for 1 minute to form a third ink layer 5 with a layer thickness of 2 μm. A thermal transfer material CI) was obtained.

Example 2. 3. 4 The formulations 4, 5, and 6 above were uniformly mixed using a propeller type stirrer to obtain coating liquids 4, 5, and 6, respectively. These coating liquids 4, 5 and 6 were respectively applied onto the first ink layer 3 obtained in the same manner as in Example 1 using an applicator, and dried with hot air at 60°C for 1 minute to obtain a layer thickness. 1.5
The second ink layer 4 had a thickness of μm.

A third ink layer 5 having a layer thickness of 2 μm was formed on each of the obtained second ink layers 4 by applying and drying the coating liquid 3 having the formulation 3 in the same manner as in Example 1. Thermal transfer materials ([1), (III) and (IV)] were obtained.

Comparative example 1. 2 The formulations 7 and 8 above were uniformly mixed using a propeller type stirrer to obtain coating liquids 7 and 8, respectively. This coating liquid 7
．． Example 1 except that 8 was replaced with coating liquid 2 of Example 1.
Coating and drying were carried out in the same manner as above to obtain thermal transfer materials (V) and (Vl) of Comparative Example 1.2, respectively.

The heat-sensitive transfer materials (1) to (Vl) thus obtained were
Cut to m width and use Canon ■ electronic typewriter - 8P4
Printing was performed on recording paper with a Beck smoothness of 2 seconds using 00X.

The printing energy was set to Vol. 4. The printing results are shown in Table 1.

Table 1 ◎: Very good.

○: Good. There is no practical problem at all.

×: Bad. Not practical.

〔Effect of the invention〕

As explained above, according to the present invention, since the water-soluble resin is contained, the heat-melting resin fine particles are not fused during the production of the heat-sensitive transfer material, but once the heat-sensitive transfer material is heated, the heat-melting resin particles are not fused. The fusion and homogenization of the meltable resin particles progress, and a sharp and clear recorded image can be obtained even on a recording medium with low smoothness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the thermal transfer material of the present invention. 2...Support 3...First ink layer 4...Second ink layer 5...Third ink layer Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] A thermal transfer material having at least a first ink layer, a second ink layer, and a third ink layer in order from the support side on a support, wherein the second ink layer is water-soluble with heat-fusible resin fine particles. containing a water-soluble resin, and the number average molecular weight of the water-soluble resin is 12.0.
00 or more.