JPS62149495A - Production of thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer recording medium in which adhesion between a coloring material layer and a base is favorable, a coated surface of the coloring material layer is homogeneous and smooth and fogging will not occur even at the time of transfer recording on a recording sheet such as an ordinary paper, by using a specified combination of a solvent, a heat- fusible substance and a resin for forming the coloring material layer. CONSTITUTION:A thermal transfer recording medium is produced by providing a coloring material layer on a base by solvent coating. In this method, a coating liquid comprising (a) a solvent, (b) a heat-fusible substance having a solubility in the solvent (a) of not less than 5wt% and (c) a resin having a solubility in the solvent (a) of not less than 0.2wt% and compatible with the heat-fusible substance (b) is applied to the base at normal temperature under the condition where the components (b) and (c) are dissolved in the component (a). The heat- fusible substance (b) preferably has a melting point of 40-100 deg.C. The softening point (by the ring and ball method) of the resin (c) is not particularly limited, but is preferably 50-200 deg.C. The coloring material layer comprises, for example, 50-90pts.wt. of the heat-fusible substance, 5-20pts.wt. of a coloring agent and 1-30pts.wt. of the resin per 100pts.wt. of the total amount of the layer.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a thermal transfer recording medium, and more specifically, a method for efficiently forming a coloring material layer that has good film adhesion to a support and has a uniform coating surface. The present invention relates to a method of manufacturing a thermal transfer recording medium.

[Prior art]

A thermal transfer recording medium has been conventionally used as a recording medium for transferring and forming an image on a recording sheet such as plain paper using a thermal printer, a thermal facsimile, or the like. This heat-sensitive transfer recording medium has at least one coloring material layer on a support, and the coloring material layer is, for example, a layer containing a coloring agent such as a pigment and a heat-fusible substance. It is being In addition, in order to obtain good reproducibility of the dye transfer image obtained from the color material layer coated on the support, the film Me, which has excellent surface smoothness and dimensional stability, is used. .

Thermal transfer recording media are manufactured by coating a coloring material layer on a support that has excellent surface smoothness and dimensional stability using a hot melt coating method or a solvent coating method.

The hot melt coating method is a method in which the composition forming the color material layer is heated to a temperature higher than its melting temperature to melt and liquefy and then applied.The solvent coating method is a method in which the composition forming the color material layer is heated to a temperature higher than the melting temperature to melt and liquefy and apply the composition. This method involves dissolving or dispersing the liquid in the liquid, applying it, and drying it. Among these, the present invention relates to a technique that belongs to the solvent coating method, and more specifically to a technique that allows solvent coating at room temperature.

Solvent coatings are generally applied at temperatures above 40°C (e.g. 5°C
It is carried out by heating to a temperature of 0 to 80°C. 18 thermofusible substances
When it is dissolved or dispersed in a medium, it can be melted at 719 degrees, which is lower than the melting point of the heat-melting substance, but as long as conventional heat-melting materials are used, it is difficult to apply it at temperatures below 40 degrees Celsius. be. In other words, a uniform coating surface cannot be obtained,
This may cause uneven transfer printing. In particular, if a heat-fusible substance with a low melting point and α is used, a uniform coated surface can be obtained, but the strength of the coated surface may be insufficient and scratches may occur during storage.

Therefore, heating coating is carried out; however, deterioration of the working environment due to evaporation of the two mediums, fluctuation (increase) in the solid content concentration in the coating liquid for forming the coloring material layer, and aggregation of the coloring material are unavoidable. Therefore, high-precision heat insulation equipment was required.

In order to solve the above problems, for example, 1.
No. 58-128897 discloses a technique in which a coloring material layer is applied using a wax (heat-melting substance) which melts in a solvent by 10% or more.

However, the heat-sensitive transfer recording medium obtained by the above method has the disadvantage that the coloring material layer is brittle, and the film adhesion between the coloring material layer and the support is poor, and background stains occur when transferred to a recording sheet such as plain paper. It also had the disadvantage of causing (fogging). Furthermore, when applying the coloring material layer, the coating is often performed while some of the wax is precipitated in the solvent, and the surface of the formed coloring material layer is often non-uniform.

Therefore, it is necessary to develop a solvent coating technology at room temperature that solves the above-mentioned drawbacks.

[Purpose of the invention]

The purpose of the present invention is to achieve good film adhesion C between the coloring material layer and the support by a solvent coating method at room temperature, to achieve a uniform and smooth coated surface of the coloring material layer, and to achieve recording properties similar to plain paper. An object of the present invention is to provide a method for producing a thermal transfer recording medium that does not generate capri even when transferred to a sheet.

[Structure of the invention]

The present inventors have conducted various studies on the constituent materials forming the coloring material layer regarding the coating of the coloring material WI on a heat-sensitive transfer recording medium using a solvent coating method. It was discovered that heavy industry problems could be solved by combining them, leading to the invention.

That is, the object of the present invention is to investigate methods for producing heat-sensitive transfer recording media 1 and 7), (1)) and (c) in which a coloring material layer is coated on a support by a solvent coating method.
Apply the coloring material layer forming coating solution containing the substance at room temperature (l)
)S! J' A method of manufacturing in which (c) is dissolved in (,, I)) is a heat-melting method that dissolves 5% by weight or more in (,) solvent ([,) solvent (,), which is particularly well-known. The present invention will be described in more detail below.

Specific examples of solvents used in the present invention include F-luene, xylene, trichlene, white spilint, etc., paraffinic solvents such as n-hexane, ligroin, and isoparaffin, and ketones such as acetone, cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone. system solvent, meta/
Alcohol solvents such as alcohol, ethanol, 2-propyl, butanol, ester solvents such as ethyl acetate, 0
Examples include water, a growth solvent such as a special solvent such as DMSO, and a mixture thereof. The amount of these solvents may be 0.5 to 50 parts by weight, preferably 1 to 19 parts by weight (1 part by weight) per 1 part by weight of the colorant layer components.

Note 11: The medium is placed at room temperature (range of about 0 to 40°C [!II)
5% by weight or more; heat-melting substances that undergo S-lysis vary depending on the solvent, but include waxes, higher fatty acids, higher alcohols, higher amides, and esters. As a specific example, when the solvent is Kijirenz, WA
X El-^X F, W^×■, WAX [lJ,
WAX OM, WAX OP, WAX GL3, W
Examples include AX KPS (hereinafter referred to as Izurera Hequist Co., Ltd. tJ1).

The melting point of these heat-melting substances is 30 to 150°C.
1 Preferably 40-100°C 1 Particularly preferably 60-100°C
90℃ is best.

The resin used in the present invention has 0.2 to 1 part of the above solvent at room temperature.
It dissolves in an amount of % or more, and has compatibility with the heat-fusible substance. Specific examples include ponyvinylbutyral, polypropylene, polyamide, cellulose acetate, polyvinyl acetate, and ethylene-ethyl acrylate.
) A) llE compound IE, ethylene-vinyl acetate copolymer,
Examples include acrylic resins such as poly7tyl/tacrylate, ronone derivatives such as polyisobutylene, petroleum resins, and the like.

The softening point (value measured by ring and ball method) of these resins is preferably 50 to 200°C, although there is no particular restriction.

The coating liquid used in the present invention contains at least one colorant. As coloring agents, there are various dyes and pigments that have been widely used in the industry. One can be used without another restriction. For example, the colorant layer (3I) can be dissolved or dispersed when melted, has a color, and is solid or semi-solid. The substance used as the colorant can include a variety of pigments known in the art.

Examples of the dye include direct dyes, acid dyes, basic dyes, disperse dyes, and oil-soluble dyes (including metal-containing oil-octadic dyes).

As pigments, mention may be made of black iso pigments (carbon black, Prussian blue, cadmium sulfide, iron oxide, laminate, etc.) and growth pigments (anthraquinone, anthurone, tri7ennooxanone, quinacridone, phthalocyanine, etc.). Lighten up.

Although the composition ratio of the coloring material layer of the present invention is not limited, for example, 50 to 90 parts of the heat-melting substance and 5 to 20 parts of the coloring material to 100 parts (parts by weight, same hereinafter) of the total amount of the coloring material layer. parts, and resins are 1 to 30 parts.

In the present invention, a so-called dispersant may be used to disperse the colorant or to keep the dispersion state stable. Specific examples include nrubitan sulfate ester, unsaturated fatty acid furkylamide, alkylimigzolin, polyacrylic acid partial fatty acid ester, alkylbenzenesulfonic acid calcium salt, and the like. These dispersants may be included in the coating material 11, t, or may be included in the coating solvent.

In addition to the above-mentioned components, the coating liquid used in the present invention 1 also contains the following ingredients:
fffli, % machining may be included. For example, it is possible to add powder or fine particles of a metal with good heat conductivity such as aluminum, copper, or zinc as a biological material. It is one step ahead of the heat transfer effect of melting, turning, or sublimation.Furthermore, vegetable oils such as castor oil, linseed oil, and olive oil, animal oils such as whale oil, and mineral oils are preferably used as softening agents. It's okay to be.

Examples of dispersion mills that can be used in the present invention include Disilver, Homomixer, Nigoo, roll mill, and sand mill.

Coating methods suitable for solvent coating a support with a colorant layer coating solution are known in the art, and these techniques can also be used in the present invention. For example, the coating solution is solvent coated using any known technique such as a reverse roll coater method, an extrusion coater method, a gravure coater method, or a wire bar coating method, and then the solvent is removed to form a color material layer of 15 μm or less. can be painted.

The support used in the present invention may be any known support, but it is desirable that the support has heat-resistant strength, dimensional stability, and surface smoothness. Heat resistance strength requires strength and dimensional stability to maintain the toughness of the support without becoming softened or plasticized by the heating temperature of a heat source such as a thermal hand, and surface smoothness requires the strength and dimensional stability of the support. The colorant layer containing the heat-fusible substance has sufficient smoothness to exhibit a good V conversion rate. The smoothness should preferably be 100!3 ec or more in the smoothness test 9 (JIS P8119) using a sandy surface, and if the smoothness is 300 sec or more, an image with better transfer rate and reproducibility can be obtained. Materials include, for example, papers such as plain paper, condenser paper, laminated paper, and coated paper; resin films such as polyethylene, polyethylene terephthalate, polyester, polystyrene, polypropylene, and polyimide; paper-resin film composites; and aluminum foil. Metal sheets such as the following are preferably used.

The thickness of the support is usually 60μ to obtain good thermal conductivity.
“It is preferably n or less, particularly 2 to 20 μm0.

Furthermore, in the thermal transfer recording medium of the present invention, the structure of the back surface fli+ of the support is []l:.

The thermal transfer recording medium of the present invention has only one coloring material layer obtained by the present invention, and may have other constituent layers such as a subbing layer, an intermediate layer, or an overcoat layer. That is, for example, examples of the undercoat layer include a silicone tray, melamine If resin, polyvinyl acetal resin, polyethylene, polyvinyl chloride, polyvinylidene chloride, fluorine, and oil. The coating can be performed prior to coating the coloring material layer.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Note that "parts" used below indicate "parts by weight."

Example 1 A coating solution for forming a coloring material layer shown below was manufactured by A.

Carbon black 8 parts ＾XV (manufactured by Hoechst, wax melting point 45-50°C) 82 parts NUC-3160 (manufactured by Nippon Unicar Co., Ltd. Ethylene-vinyl acetate copolymer, softening, α88°C) 10 parts xylene
600 copies At this time, it was confirmed that X and N[IC-3160 were completely dissolved in xylene.

This coating liquid was applied onto a polyethylene terephthalate film with a thickness of 6 μm using a roll coater at room temperature (20°C), dried by blowing warm air, and then a thermal transfer film having a coloring material layer with a dry V thickness of 3 μm was applied. A recording medium sample (A) was obtained.

In addition, the above coating solution minus carbon black was coated on a polyethylene terephthalate film under the same conditions *a After drying, observation under a microscope revealed that the coating was completely uniform and NUC-3160 was compatible with Δxv. It was confirmed that

Example 2 The following colors (yellow, magenta, cyan, blank)
A coating solution for forming a coloring material layer was prepared.

Color material* 8 parts W to X
V (+'+ij 6)
76th part NUC-:
! 100 (+iη description) 8 parts Ri-in 1-D-200 (manufactured by Nippon Zeon Co., Ltd. Aliphatic hydrocarbon type!j (fat softening point 100°C) 3 parts 1 part / 400 parts real color material H＋ocnL Yet four
12 (C, 1, 21090) Magenta: Pigm
enL Itcd 57: 1 (C4, 15850:
1) Cyan: Pig+oeut [1lue
15 (C0I, 74160) Blank: Carbon blank At this time, it was confirmed that NUC-3160 and Finton D-200 were completely dissolved in toluene.

This coating solution was coated on a polyethylene terephthalate film with a thickness of 6 μ'' at room temperature (25° C.) by gravure 4-color printing, and a thermal transfer recording medium sample (B) having a 4-color color material layer with a dry film thickness of 3 μIII was obtained. I got it.

Furthermore, when the above coating solution with the colorant removed was applied onto a polyethylene terephthalate film and observed under a microscope after drying, it was found that the film was completely uniform [C-3160 and Clenton D-200 had a compatibility with WΔXV of 1]. ``I confirmed that it was working properly.

Comparative Example 1 NLIC-31G from coloring material layer forming coating 1a of Example 1
The same procedure as in Example 1 was carried out except that O was removed.
J.

A medium sample (C) was obtained.

Comparative Example 2 In fact, in Ike Example 1, Ichihe X DJ instead of WAX V
(Hoechst red wax melting 5-''774-80℃)
A coating liquid for forming a coloring material layer was prepared in the same manner as in Example 1 except that 5.1 was used. At this time, X [l
J is partially precipitated.

Using this coating liquid, a thermal transfer recording medium sample (D) was obtained in exactly the same manner as in Example 1.

Comparative Example 3 In fact, in Example 1, Stylon+379 (polystyrene softened by Lugu Co., Ltd.) was used instead of NUC-3160.
A coating liquid for forming a coloring material layer was prepared in the same manner as in Example 1 except that ζ (91° C.) was used. At this time, -8XV and Styron 679 were completely dissolved in xylene.

Using this coating liquid, heat-sensitive Il was prepared in exactly the same manner as in Example 1.
I tried the photo recording medium and got "+ (E).

After removing the carbon black from the above coating solution, it was coated on a polyethylene terephthalate film and dried, and then observed with a microscope.
It was found that Styron 679 has no compatibility with ΔXV.

The thermal transfer recording medium samples obtained in the above examples and comparative examples were printed using a thermal printer (heating element density 8doL/
When a prototype (Ling) equipped with an IaIIl thin film type line thermal head was used to print on uniformly running paper with a CC Beck smoothness of 200 seconds, the results shown in Table 1 were obtained. For printing, samples (A), (C), (D), and (E) were printed in different colors, and samples <8) were printed in multiple colors.

Table 1 -X1) Observe the coloring material layer coating film with a magnifying glass.

Book 2) After bending the sample strongly, the coloring material layer was observed with a magnifying glass and evaluated using the following three-step method.

○No peeling of the coloring material layerΔ Some peeling of the coloring material layer is observed Evaluation was performed using a three-step method.

○ No stains at all △ Slight stains × Significant stains As is clear from Table 1, the samples obtained by the present invention had a uniform coated surface, and the coloring material layer and support were , :;λf
・It has good texture and suppresses the occurrence of scumming.

〔Effect of the invention〕

11 - Implementation of the invention (The following effects can be obtained from this.

(1) Support (has good film adhesion and a homogeneous coating surface)
1 layer can be applied at room temperature.

(2) Thermal transfer recording media are excellent printed products 71
1 on a recording sheet such as a sheet of paper]
There is no occurrence of rJ slippage.

<3) High F+ in the coating process? There is no need for a heat insulation fim, and it is possible to prevent deterioration of the working environment and pollution caused by evaporation of the solvent.

Claims (3)

[Claims] (1) In a method for producing a thermal transfer recording medium in which a coloring material layer is coated on a support by a solvent coating method, a coating for forming a coloring material layer containing each of the following substances (a), (b) and (c) The solution is at room temperature, and (b) and (c) are (a)
1. A method for producing a thermal transfer recording medium, which comprises coating the medium in a dissolved state. (a) Solvent (b) A thermofusible substance that dissolves at least 5% by weight in the solvent (a) (c) Dissolves at least 0.2% by weight in the solvent (a) and is compatible with the thermofusible substance (b) resin with (2) The method for producing a heat-sensitive transfer recording medium according to claim 1, wherein the heat-melting substance (b) has a melting point in the range of 40 to 100°C. (3) The method for producing a thermal transfer recording medium according to claim 1, wherein the resin has a softening point of 50 to 200°C.