JP3152981B2 - Thermal transfer recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a thermal transfer recording medium used in a thermal transfer recording apparatus using a thermal head such as a word processor, a facsimile, and a bar code. More specifically, while maintaining high thermal sensitivity such as cover wrapping properties on paper with low smoothness and dot reproducibility, while improving high-temperature and / or long-term storage stability, The present invention relates to a thermal transfer recording medium in which troubles in running are prevented.

[0002]

2. Description of the Related Art Thermal transfer recording methods are widely used because the apparatus is simple, has low noise, is compact, is inexpensive, and can easily record on plain paper. However, the printing quality is easily affected by the surface smoothness of the receiving paper, and it has been difficult to perform clear printing on the receiving paper having poor surface smoothness. In addition, with the recent increase in the speed and resolution of thermal heads, thermal heads have become easier to store heat. As a result, the temperature around the heat-generating part also rises, so that the background of the transfer paper tends to be soiled. Has occurred.

In order to solve the above problem, recently, a heat-resistant protective layer for preventing sticking is provided on one surface (hereinafter referred to as a back surface) of a substrate, and the other surface (hereinafter referred to as a front surface) of the substrate is provided. A styrene resin with a laminated structure of a heat-meltable ink layer, a first thermal transfer layer which is a colored layer, and a styrene resin for improving printability on low-smooth paper / adhesiveness / ground stain resistance. A thermoplastic resin such as an acrylic resin, a polyamide resin, a butyral resin, a vinyl chloride-vinyl acetate copolymer resin, and an ethylene-vinyl acetate copolymer resin as a main component, and a tackifier resin, a wax, a colorant, and the like mixed as necessary. In general, a structure in which a second thermal transfer layer is formed is provided.

However, in a ribbon having such a structure, during high-temperature storage or long-term storage in a roll state, the transfer of the top thermal transfer layer to the heat-resistant protective layer on the back surface occurs, and troubles often occur in printing and running. . According to the structure of the conventional heat-sensitive transfer recording medium, some problems have been solved in terms of printability such as cover wrapping property on low-smooth paper, dot reproducibility, and ground stain resistance. On the other hand, in order to obtain clear printing with high thermal sensitivity, it is necessary to use a thermoplastic resin having a low softening point as a main component of the top layer as the second thermal transfer layer. However, when a resin having a low softening point is used for the top layer, which is the second thermal transfer layer, if the resin is stored at a high temperature or stored for a long period of time in a roll state, the resin of the top layer is provided directly on the back surface of the substrate or on the back surface. To the heat-resistant protective layer, which reduces the print quality on low-smooth paper due to reduced cover wrapping properties, reduced print quality due to dirt on the thermal head, the occurrence of stick phenomena, and the running of the ribbon in the cassette. Problems such as the occurrence of the above troubles have occurred.

That is, the conventional thermal transfer recording medium is incompatible with storage properties such as high-temperature and long-term storage, and printability such as cover wrapping property on low smooth paper, dot reproducibility, and ground stain resistance. was there. In order to solve the above-mentioned problem, the inventor first reacts one or two or more thermoplastic resins containing an atomic group having a bonding moment of 1.0 Debye or more with a terminal of dimethylpolysiloxane by the second thermal transfer layer. A coating composition containing a silicone oil into which a reactive functional group has been introduced is applied, and in particular, a reactive functional group to be introduced into the terminal of dimethylpolysiloxane has a functional group equivalent of 2
2,000 g / mol or less thermal transfer recording medium (Japanese Patent Application No.
No. 154,052), the second thermal transfer layer is bonded to a thermoplastic resin having at least one group or a bonding group selected from the group consisting of a hydroxyl group, a carboxyl group and an amide bond, and to a Si atom excluding the terminal of dimethylpolysiloxane. A heat-sensitive transfer recording medium (Japanese Patent Application No. 2-154053) obtained by applying a composition containing an amine-modified silicone oil in which an amine group is introduced so as to have an amine equivalent of 2000 g / mol or less to a methyl group. Proposed.

However, these thermal transfer recording media have been improved in stability at high temperature storage and long-term storage as compared with conventional thermal transfer recording media as a result of detailed follow-up tests. As a result of the preservation, the second thermal transfer layer tends to migrate, and as a result, the higher the printing temperature, the more likely it is that a driving problem occurs, and the result of the measurement of the coefficient of friction of the surface of the thermal transfer layer shows a decrease over time. Because of this, it was found that the running performance was unstable. That is, it was presumed that a part of the used terminal-reactive silicone oil or amine-modified silicone oil bleeded to the surface of the second thermal transfer layer more than originally expected. In other words, still, high-temperature and long-term storage, and cover wrap on low-smooth paper,
The problem of incompatibility in terms of dot reproducibility, printability such as ground stain resistance, and stable running performance has not been solved.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conventional product in which the second thermal transfer layer shifts to the rear surface, and even in a high-temperature and long-term storage state in which a sticking trouble occurs due to sticking. Prevents the thermal transfer layer from migrating to the back surface of the base material or the heat-resistant protective layer provided on this back surface, and significantly improves the sharpness of transfer to the transfer paper having poor smoothness and the background stain on the transfer paper. It is also an object of the present invention to provide a thermal transfer recording medium that smoothly stabilizes the tape running property.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a compound composition containing a specific thermoplastic resin, a specific silicone oil, and a specific crosslinking agent as a second thermal transfer layer. And found that the problem could be solved by applying the present invention, and completed the present invention.

That is, the present invention provides a heat-sensitive transfer recording medium having a laminated structure in which a first heat transfer layer as a colored layer is provided on a base material, and a second heat transfer layer is further provided thereon. A hydroxyl group, a carboxyl group, and a thermoplastic resin having at least one group or a bonding group selected from the group consisting of an amine bond, and a methyl group bonded to a terminal or a Si atom excluding the terminal of dimethylpolysiloxane as an amine equivalent. A heat-sensitive transfer recording medium which is a compounded composition comprising an amine-modified silicone oil having an amine group introduced therein so as to have a concentration of 2,000 g / mol or less and an aziridine-based crosslinking agent.

Next, the configuration of the present invention will be described. As the base material, a plastic film having relatively high heat resistance, such as polyester, polycarbonate, and polyimide, having a thickness of 2 to 20 μm, cellophane, paper, or the like can be used. If necessary, the surface in contact with the thermal head may be silicone or fluorine based. A heat-resistant protective layer or a stick prevention layer made of a polymer may be provided.

The heat-meltable ink of the first thermal transfer layer is a colorant,
It is composed of a vehicle and various additives. As the colorant, carbon black, organic pigments, dyes and the like can be used alone or in combination. Preferably, a material having a sufficient coloring density and not discoloring due to light, heat, temperature and humidity, a solvent, or the like is preferably selected. Melting point of 45 for vehicle
The main component is wax at ~ 120 ° C, and one or more selected from paraffin wax, carnauba wax, microcrystalline wax, candelilla wax, polyethylene wax, wood wax, beeswax, fatty acid amide, fatty acid ester and the like are used. However, the present invention is not particularly limited. In addition to the above configuration, various additives such as a fixing agent, a dispersing agent, and a leveling agent made of a thermoplastic resin may be added to the hot-melt ink as needed. The composition and thickness of the first thermal transfer layer are determined by the required print density and thermal sensitivity, but the thickness is preferably in the range of 0.1 to 10 μm.
Preferably, the range is 2 to 5 μm.

Next, the composition for forming the second thermal transfer layer will be described. Examples of the thermoplastic resin having at least one group or a bonding group selected from the group consisting of a hydroxyl group, a carboxyl group, and an amide bond (hereinafter, simply referred to as a thermoplastic resin) include cellulose derivatives, polyvinyl alcohol derivatives, and polyamide resins. Having a softening point of 50 to 20
One or more thermoplastic resins at 0 ° C., preferably 70 to 150 ° C., are used. More preferably, the amine-modified silicone oil, which is another component of the second thermal transfer layer, has good miscibility with an aziridine-based cross-linking agent, and a mixture with these is used as an alcohol, ketone, ester, or hydrocarbon. Select a thermoplastic resin that dissolves in volatile solvents such as. This is because these blended compositions are dissolved in these solvents and are applied in a thin film form on the first thermal transfer layer.

A specific silicone oil (hereinafter simply referred to as an amine-modified silicone oil), which is a second component of the second thermal transfer layer, has a methyl group bonded to a terminal or an Si atom excluding the terminal of dimethylpolysiloxane. Is an amine-modified silicone oil obtained by reacting an aliphatic amine compound or the like with an amine group, and one or more of them are used. In order to obtain a blended composition that meets the purpose of the present invention by mixing with the thermoplastic resin, it is necessary to use a compound having an amine group introduced therein so that the amine equivalent becomes 2000 g / mol or less. Amine equivalent is 2000g /
In the case of a compounded composition using an amine-modified silicone oil in excess of mol, the affinity for the thermoplastic resin is inferior and the applied thin film is non-uniform and the amine-modified silicone oil bleeds. It is not preferable because it causes defects such as phase separation in a liquid state.

The aziridine-based crosslinking agent, which is the third component of the second thermal transfer layer, promotes the reaction between the thermoplastic resin and the amine-modified silicone, and bleeds excess amine-modified silicone oil onto the surface of the second thermal transfer layer. The purpose is to prevent. As the aziridine-based crosslinking agent in the present invention, tris-1- (2-methylaziridine) phosphine, triethylenemelamine, tetramethylolmethane-tri-β-aziridinylpropionate, tri-1-
Aziridinylphosphine oxide, trimethylolpropane-tri-β-aziridinylpropionate, N, N
-One or two or more of hexamethylene-1,6-bis (1-aziridinecarboxamide) and the like are used.

Next, a method for preparing a coating composition using the above materials will be described. To mix the thermoplastic resin, the amine-modified silicone oil and the aziridine-based cross-linking agent, a method of dissolving and stirring them using a single or mixed solvent for dissolving them, and if necessary, adding the solvent, a roll mill, a pressure kneader After kneading using a kneading machine capable of applying a high shearing force such as described above, there is a method of letting down the kneaded product with the solvent. The mixing ratio of the thermoplastic resin, the amine-modified silicone oil and the aziridine-based crosslinking agent depends on the type of each material used and the quality of the intended thermal transfer recording medium, but the amine-modified silicone oil is 100 parts by weight of the thermoplastic resin. 5 to 100 parts by weight, based on the aziridine-based crosslinking agent,
Add 1 to 50 parts by weight per part by weight. When the amount of the amine-modified silicone oil is less than 5 parts by weight, the characteristics of the amine-modified silicone oil are not exhibited, and when it exceeds 100 parts by weight, bleeding and phase separation easily occur, which is not preferable.
If the amount of the aziridine-based crosslinking agent is less than 5 parts by weight based on the amine-modified silicone oil, no crosslinking effect is exhibited,
If it exceeds 50 parts by weight, unreacted substances will have an adverse effect. still,
If necessary, a low to medium molecular resin represented by a tackifier resin or the like may be added for the purpose of adjusting the softening point of the thermoplastic resin, and further, an additive such as a surfactant and a leveling agent May be added.

The amount of the solvent to be added to the coating composition depends on the type of the resin, the amine-modified silicone oil and the aziridine-based crosslinking agent and their mixing ratio, the type of the solvent, the coating method,
Although it depends on the thickness of the thermal transfer layer, it is preferably 50 to 99.5% by weight based on the total amount of the coating composition. The coating composition obtained from the above-mentioned material is subjected to a reaction with an aziridine-based cross-linking agent between the thermoplastic resin and the amine-modified silicone oil under heating and / or stirring, if necessary, before coating. May be.

In order to obtain the thermal transfer recording medium of the present invention from the above-mentioned composition, the first thermal transfer layer may be formed on the surface of the base material provided with a heat-resistant protective layer on the back side by a hot melt method or a solvent method, if necessary. After constructing using the composition, the composition is applied using a known coating method, that is, a gravure roll method, a kiss roll method, a Meyer bar method, and the like, and the solvent is volatilized to construct a second thermal transfer layer to obtain a product. . The thickness of the second thermal transfer layer is 0.
In the range of 0.5 to 5.0 μm, preferably 0.1 to 5.0 μm.
About 2.0 μm is good. Also, if necessary, the base material and the first
A release layer or an adhesive layer may be provided between the thermal transfer layers.

[0018]

The thermal transfer recording medium having a heat-fusible ink layer having a laminated structure according to the present invention has the following excellent properties. In the second thermal transfer layer, the amine group in the amine-modified silicone oil attacks and binds to the hydroxyl group and / or the carboxyl group in the thermoplastic resin and / or the terminal hydrogen atom of the amide bond, and these functional groups and atomic groups are bonded. Depending on the type, blending ratio, mixing method, etc., hydrogen bonds or other bonds are generated, and part or most of the surface of the second thermal transfer layer is covered with dimethylpolysiloxane having a small surface free energy, resulting in high temperature. In addition, preservability such as long-term storage is dramatically improved. The aziridine-based crosslinking agent has the function of accelerating the above reaction quickly and effectively. On the other hand, since the thermoplastic resin is partially bonded to the amine-modified silicone oil in the molecule, the inherent properties of the thermoplastic resin, such as film forming properties and thermal responsiveness, are present without any change. There is no reduction in printability such as cover wrapping property on smooth paper, dot reproducibility, and ground stain resistance.

[0019]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. (Example 1) A polyester film having a thickness of 4.0 µm was used as a base material. A heat-resistant protective layer made of silicone-modified urethane resin for stick prevention is provided on the back surface of the substrate. As the first thermal transfer layer components, 15% by weight of ethylene-vinyl acetate copolymer resin, 20% by weight of carbon black, carnauba wax 2
A compounded composition consisting of 0% by weight and 45% by weight of paraffin wax is sufficiently kneaded using a heated three roll for ink. The hot-melt ink thus prepared was applied on the surface of the substrate by a hot-melt gravure roll to a thickness of 3.0 μm to form a first thermal transfer layer.

As a second thermal transfer layer component, 50 parts by weight of polyvinyl butyral having a hydroxyl group in a molecule, 25 parts by weight of a ketone resin as a softening point regulator, and a methyl group bonded to Si atoms excluding the terminal of dimethylpolysiloxane. 25 parts by weight of an amine-modified silicone oil (KF857 manufactured by Shin-Etsu Chemical Co., Ltd.) into which an amine group is introduced so that the amine equivalent becomes 830 g / mol; trifunctional aziridine-based cross-linking agent [PZ-33 manufactured by Nippon Shokubai Chemical Co., Ltd.] 5 parts by weight were put into ethyl acetate and sufficiently stirred to prepare a 10% by weight ethyl acetate solution for coating. This solution is refluxed at 60 ° C.
After stirring for 10 hours, the mixture was cooled to obtain a solution for coating the second thermal transfer layer. The surface layer after drying was coated on the first thermal transfer layer with a wire bar so as to have a thickness of 1 μm, and dried to form a second thermal transfer layer, thereby obtaining a thermal transfer recording medium of the present invention.

Example 2 The procedure was the same as in Example 1 until the first thermal transfer layer was coated.
As the second thermal transfer layer component, 60 parts by weight of an alcohol-soluble polyamide resin having an amide bond in the molecule, and an amine equivalent of 840 g / mol at both ends of dimethylpolysiloxane.
Amine-modified silicone oil having an amine group introduced therein such as X-22-161A manufactured by Shin-Etsu Chemical Co., Ltd.
0 parts by weight, 15 parts by weight of a trifunctional aziridine-based cross-linking agent [PZ-33 manufactured by Nippon Shokubai Kagaku Co., Ltd.], 10 parts by weight of isopropyl alcohol, and 10 parts by weight of ethyl acetate were sufficiently kneaded using a heated two rolls. Later, this was put into ethyl acetate and sufficiently stirred to prepare an ethyl acetate-isopropyl alcohol solution for coating having a concentration of 10% by weight.
After stirring at 60 ° C. for 5 hours under reflux and cooling, a solution for coating the second thermal transfer layer was obtained. After drying, the surface layer was coated with a wire bar so as to have a thickness of 1 μm, and dried to form a second thermal transfer layer, thereby obtaining a thermal transfer recording medium of the present invention.

Comparative Example 1 A 10% by weight concentration ethyl acetate solution for coating was removed from the coating composition for coating of the second thermal transfer layer, except for the aziridine-based cross-linking agent, without heating under reflux. Each coating agent was applied under the same conditions as in Example 1 to obtain a thermal transfer recording medium.

Comparative Example 2 The aziridine-based cross-linking agent was removed from the coating composition for the second thermal transfer layer, and the ethyl acetate-isopropyl alcohol solution having a concentration of 10% by weight was not subjected to heat treatment under reflux. Then, each coating agent was applied under the same conditions as in Example 2 to obtain a thermal transfer recording medium.

Next, the following test results obtained after winding the heat-sensitive transfer recording medium obtained by the above operation into a roll and storing at 60 ° C. for 24 hours are shown in Table 1. The following test results are shown in Table 2. Test items Microscopic observation of the degree of transfer of the second thermal transfer layer to the stick prevention layer side Measurement of the friction coefficient of the surface of the second thermal transfer layer (JIS P-
8147 Conforms to the paper friction test method, the object is Uniword Processor paper manufactured by Mitsubishi Pencil Co., Ltd.) Printing test on transfer paper with a Beck smoothness of 50 seconds using a commercially available thermal transfer printer

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

As is clear from the above test results, the thermal transfer recording medium of the present invention is, as compared with the conventional thermal transfer recording medium, the back surface of the thermal transfer layer at the time of high temperature and long-term storage or the heat-resistant protective layer. This is a heat-sensitive transfer recording medium having an excellent laminated structure, in which transfer to a transfer paper is prevented, sharpness of transfer to a transfer paper having inferior smoothness, and background smear of the transfer paper are significantly improved.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A heat-sensitive transfer recording medium having a laminated structure in which a first thermal transfer layer, which is a colored layer, is provided on a base material, and a second thermal transfer layer is further provided thereon. A thermoplastic resin having at least one group or a bonding group selected from the group consisting of a group and an amine bond;
The methyl group attached to the i-atom has an amine equivalent of 20
A heat-sensitive transfer recording medium, which is a compounded composition comprising an amine-modified silicone oil having an amine group introduced therein so as to be not more than 00 g / mol and an aziridine-based crosslinking agent.