JP2792380B2 - 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 a thermal transfer recording medium which can be thermally transferred by a thermal medium such as a thermal head, and more particularly, it can print on general-purpose paper and plastic substrates and has excellent abrasion resistance. The present invention relates to a thermal transfer recording medium which is excellent in gradation expression to give a printed matter.

[0002]

2. Description of the Related Art A thermal transfer recording medium has conventionally been used as a recording medium for transferring and forming an image on a recording sheet such as plain paper by a thermal printer, a thermal facsimile or the like.

[0003] This thermal transfer recording medium is a thermal transfer recording medium in which a recording layer comprising a heat-fusible substance such as wax and a coloring agent such as a dye or a pigment is provided on a substrate, or a recording medium comprising a substrate and a recording layer. There is known a thermal transfer recording medium in which a release layer made of a heat-fusible substance such as wax is provided between them. However, the thermal transfer recording medium having a recording layer containing a wax or a release layer has good dot reproducibility and sensitivity, but has low mechanical strength. There is a disadvantage that the adhesiveness with the polymer is poor.

In order to remedy this drawback, a method has been adopted in which a thermoplastic resin is added to one or both of the release layer and the recording layer. However, in this case, although a slight improvement is observed, a large amount of the wax component is still present, so that the abrasion resistance and the overlap transfer property are similarly deteriorated. In addition, when only a thermoplastic resin is used, there has been a problem that adhesion to a base material becomes strong and transfer becomes difficult, and heat sensitivity deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention enables clear printing on general-purpose paper and plastic substrates, and has improved abrasion resistance and overlap transferability, as compared with conventional thermal transfer recording media. An object of the present invention is to provide a thermal transfer recording medium which is excellent and can obtain a gradation image.

[0006]

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and the invention according to claim 1 is to form a release layer and a recording layer on a heat-resistant base material. In a thermal transfer recording medium formed by sequentially laminating, the release layer has a glass transition temperature of 50 to 100 ° C. and a molecular weight of 2000 to 2000.
A thermal transfer recording medium containing at least an acrylic resin in the range of 20,000, and wherein the recording layer contains at least an epoxy resin having a melting point of 60 to 100 ° C. and a melt viscosity at the melting point of 10,000 poise or less, and a coloring agent. I will provide a.

A second aspect of the present invention is based on the first aspect of the present invention, wherein the release layer has a glass transition temperature of 50 to 100.
The present invention provides a thermal transfer recording medium characterized by adding 0 to 60 parts by weight of a polyester resin having a molecular weight of 2,000 to 20,000 based on 100 parts by weight of the total solid content of the release layer.

Hereinafter, the present invention will be described in detail. The substrate used for the thermal transfer recording medium of the present invention is a film having heat resistance, high dimensional stability and high surface smoothness. Specifically, a polyester film having a thickness of 2 to 10 μm is exemplified. Note that a layer for preventing sticking to the thermal head may be provided on the back surface of the base material.

The release layer of the present invention has a glass transition temperature of 50 to 50.
It contains at least an acrylic resin at 100 ° C. and a molecular weight in the range of 2,000 to 20,000.

The acrylic resin having a glass transition temperature (Tg) specifically includes polyacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyisobutyl methacrylate, polyglycidyl methacrylate, and polyhydroxy methacrylate. It is appropriately selected from ethyl, acrylic acid-methyl methacrylate copolymer, and isobutyl acrylate-acrylamide copolymer. If the glass transition temperature is lower than the above-mentioned temperature, blocking tends to occur during storage of the printed matter after transfer. On the other hand, if the temperature is higher than the above-mentioned temperature, thermal sensitivity decreases, high energy is required at the time of transfer, and peeling off from the substrate becomes incomplete.

Further, even if the glass transition temperature is within the above range, if the molecular weight is less than the above range, the sensitivity is improved, but blocking tends to occur during storage. Further, if the ratio is more than the above, thermal sensitivity decreases, high energy is required at the time of transfer, and further, printability and transferability are reduced, which is not preferable.

On the other hand, the release layer component has a glass transition temperature of 5
A polyester resin having a molecular weight in the range of 0 to 100 ° C and a molecular weight of 2000 to 20,000 is subjected to a total solid content of the release layer of 100.
You may add 0-60 weight part with respect to weight part.

The polyester resin having a glass transition temperature (Tg) is appropriately selected from linear saturated polyester resins formed by polycondensation of a dicarboxylic acid component and a diol component. When the glass transition temperature is lower than the above-mentioned temperature, the blocking resistance in storage of the transferred printed matter decreases. On the other hand, if the temperature is higher than the above-mentioned temperature, thermal sensitivity is lowered, high energy is required for printing, and the printability is deteriorated.

Further, even if the glass transition temperature is within the above range, if the molecular weight is less than the above range, the blocking resistance in storage of the transferred printed matter decreases. In addition, if the ratio is more than the above, the thermal sensitivity is lowered, high energy is required for printing, and the printability is deteriorated.

The addition amount of the polyester resin is 0 to 60 parts by weight based on 100 parts by weight of the total solid content of the release layer. When the addition amount is 60 parts by weight or more, the adhesive strength between the substrate and the release layer is increased, which causes a decrease in thermal sensitivity.

Further, a thermoplastic resin other than an acrylic resin and a polyester resin and a lubricant may be mixed with the release layer component in an amount of 0 to 20 parts by weight based on 100 parts by weight of the total solid content of the release layer. Here, the thermoplastic resin is
For example, vinyl chloride resin, polyamide resin, epoxy resin and the like can be mentioned. On the other hand, the lubricant includes, for example, natural waxes such as Teflon powder, polyethylene powder, animal-based, plant-based, mineral-based and petroleum-based, and synthetic hydrocarbons. System, modified wax system, aliphatic alcohol and acid system, fatty acid ester and glycerite system, hydrogenated wax system, synthetic ketone, amine and amide system, chlorinated hydrocarbon system, synthetic animal wax system, alpho-olefin wax system, etc. And a metal salt of stearic acid.

Next, the recording layer of the present invention has a melting point of 60-10.
0 ° C and melting viscosity at melting point 10,000 poise
It consists of the following epoxy resin and coloring agent.

The epoxy resin having the melting point specifically includes bisphenol A type, novolak type, brominated type, alicyclic type epoxy resin and the like, and is appropriately selected from these. If the melting point is lower than the above-mentioned temperature, blocking occurs during storage. On the other hand, if the temperature is higher than the above-mentioned temperature, thermal sensitivity is lowered and high energy is required for printing, which is not preferable.

Further, even if the melting point falls within the above range, if the melt viscosity is higher than the above range, the thermal transferability decreases, and it is difficult to obtain a uniform transferred image in printing.

As the colorant, inorganic and organic pigments are preferable in consideration of the weather resistance of the image, and specific examples thereof include carbon black, oillet, and phthalocyanine blue. And a color visible image can be obtained.

The composition of the recording layer mainly composed of the above-mentioned respective components is such that the colorant is 10 to 30 parts by weight, the epoxy resin is 70 to 90 parts by weight, and the total solid content of the recording layer is 100 parts by weight. It is desirable for the layer thickness to be 0.5 to 2 μm.
Incidentally, a dispersant may be added.

In the production of the thermal transfer recording medium of the present invention, first,
The release layer composition is uniformly dispersed / dissolved with a suitable solvent to produce a release layer paint. The paint is applied and dried on a substrate by a coating method such as bar coating, blade coating, air knife coating, gravure coating or roll coating to form a release layer. Next, the recording layer composition is uniformly dispersed / dissolved with an appropriate solvent to produce a recording layer paint. The coating is performed by laminating and drying the coating by the coating method described above to provide a recording layer.

[0023]

The release layer of the present invention has a good response to heat and has the property that the transfer of the recording layer is possible even at low energy in order to facilitate the release from the base material. It is easy to transfer to a base material, has one-dot forming ability and reproducibility, has gradation expression power, and provides printed matter excellent in abrasion resistance and transparency in lamination transfer.

[0024]

EXAMPLES The thermal transfer recording medium of the present invention will be described in detail with reference to examples.

[Example 1] <Composition of coating for release layer> 5 g of azobisisobutylnitrile (AIBN) and 250 g of benzene were added to 100 g of ethyl methacrylate and stirred, and the mixture was stirred at 60 ° C for about 15 hours under a nitrogen atmosphere for about 15 hours. After polymerization, Tg 65 ° C, molecular weight 1
0000 acrylic resin was obtained.

The resulting acrylic resin dissolved in an organic solvent was used as a release layer paint.

<Composition of Recording Layer Paint> Epoxy resin (melting point: 83 ° C .; melt viscosity: 6000 poise) (EP1003 manufactured by Yuka Shell Epoxy Co., Ltd.) 80 parts by weight Pigment 20 parts by weight

On a 3.5 μm-thick polyethylene terephthalate film having a sticking prevention layer previously provided on the back surface, the release layer paint is dried to a dry weight of 0.5 g / m ² using a gravure coater or a bar coater. , And dried to form a release layer. The recording layer paint was applied on the layer by a gravure coater or a bar coater so as to have a dry weight of 1.0 g / m ² and dried to form a recording layer, thereby producing a thermal transfer recording medium.

The thermal transfer recording medium was transferred onto a transfer paper (general paper, synthetic paper, OHP sheet, etc.) using a thermal printer.

Example 2 <Composition of Release Layer Coating> 50 g of isobutyl acrylate and 50 g of acrylamide were combined with 5 g of azobisisobutylnitrile.
And 250 g of benzene, and the mixture is stirred.
Radical polymerization is carried out under nitrogen atmosphere for
C., a copolymer having a molecular weight of 15,000 was obtained.

A solution obtained by dissolving the obtained copolymer in an organic solvent was used as a paint for a release layer.

<Composition of coating material for recording layer> Epoxy resin (melting point: 69 ° C .; melt viscosity: 3000 poise) (Epiclon 1055, manufactured by Dainippon Ink and Chemicals, Inc.) 70 parts by weight Pigment 30 parts by weight

The coating method, the paper to be transferred and the transfer method are described in Example 1.
Is the same as

Example 3 Except that the components of the release layer were changed,
This is similar to the first embodiment.

<Composition of release layer paint> A mixture of 60 parts by weight of the acrylic resin having a Tg of 60 ° C. and a molecular weight of 10,000 obtained in Example 1 and 40 parts by weight of a linear saturated polyester resin (Byron 200 manufactured by Toray Industries, Inc.) Was used as a release layer paint.

Example 4 Except that the components of the release layer were changed,
This is similar to the first embodiment.

<Composition of release layer paint> 50 parts by weight of an acrylic resin having a Tg of 60 ° C. and a molecular weight of 10,000 obtained in Example 1, 45 parts by weight of a linear saturated polyester resin (Elitel 3200 manufactured by Unitika Ltd.) and polyethylene wax 5 A mixture of parts by weight was used as a release layer paint.

Comparative Example 1 Except that the components of the release layer were changed,
This is similar to the first embodiment.

<Composition of release layer paint> Polymethyl methacrylate (Tg 114 ° C., molecular weight 12,000)

[Comparative Example 2] Except that the components of the release layer were changed,
This is similar to the first embodiment.

<Composition of release layer coating composition> To 100 g of butyl methacrylate, 5 g of azobisisobutylnitrile and 250 g of benzene were added and stirred, and radical polymerization was carried out at 60 ° C. for about 15 hours under a nitrogen atmosphere. An acrylic resin having a molecular weight of 10,000 was obtained.

The obtained acrylic resin dissolved in an organic solvent was used as a release layer paint.

[Comparative Example 3] Except that the components of the release layer were changed,
This is similar to the first embodiment.

<Composition of release layer paint> Acrylic resin (Tg 75 ° C., molecular weight 30,000) (Dianal 113 manufactured by Mitsubishi Rayon Co., Ltd.)

Comparative Example 4 A recording layer component was changed, except that
This is similar to the first embodiment.

<Composition of Recording Layer Paint> Epoxy resin (melting point: 128 ° C .; melt viscosity: 15,000 poise) (Epicoat 1007 manufactured by Yuka Shell Epoxy Co., Ltd.) 80 parts by weight Pigment 20 parts by weight

[Comparative Example 5] Except that the components of the recording layer were changed,
This is similar to the first embodiment.

<Composition of Recording Layer Coating Material> Epoxy resin (melting point: 42.5 ° C .; melt viscosity: 1000 poise) (Ripoxy 90 manufactured by Showa Polymer Co., Ltd.) 80 parts by weight Pigment 20 parts by weight

Printability of Examples 1 to 4 and Comparative Examples 1 to 5,
Table 1 shows the results of the releasability, resistance, transparency, storage stability of the recording medium, and storage stability of the printed matter. Each data was tested by the following method.

[0050]

[Table 1]

Printability: The sharpness of the transferred image and the state of dot formation were evaluated by microscopic observation and an image processing apparatus. In addition, those having an unstable shape of one dot were regarded as defective.

Releasability: The recording layer completely peeled off from the substrate after thermal transfer was regarded as good, and the incomplete peeling was regarded as poor.

Resistance: The transferred image of the recording medium on which the overlap-transferred product was scratched with a nail and the thermal transfer was performed without tailing or disturbance was determined as good, and the image with disordered image was determined as defective.

Transparency: The image transferred to the OHP sheet is
Project with OHP, and if the image has transparency, it is good
Those that were cloudy were judged to be defective because they were not transparent.

Storage property: 2 at 40 ° C. and 90% RH atmosphere
It was left for 4 hours or more, and a sample in which no blocking occurred between the recording layer surface and the back surface was evaluated as good, and a sample in which blocking occurred was evaluated as defective.

Preservability: The formed recording medium is transferred and printed on a transfer-receiving member, and the printed matter is stacked several times on a sheet-by-sheet basis.
The print was left for 24 hours or more in an atmosphere of 0 ° C. and 90% RH.

[0057]

As described above, the thermal transfer recording medium according to the present invention is provided with a release layer having both easy releasability from the substrate and adhesion to the already-transferred layer during the overlap transfer. Since both the layer and the recording layer are excellent in thermal characteristics and storage characteristics, the thermal sensitivity, abrasion resistance and overlay transferability in transfer to general-purpose paper and plastic substrates are improved. Further, since the dot forming ability and the reproducibility are excellent, a gradation image can be obtained.

[0058]

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a thermal transfer recording medium of the present invention.

[Explanation of symbols]

 Reference Signs List 11 recording layer 12 release layer 13 base material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-255589 (JP, A) JP-A-61-244593 (JP, A) JP-A-3-248888 (JP, A) JP-A 63-244 199683 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (2)

(57) [Claims] 1. A thermal transfer recording medium comprising a release layer and a recording layer sequentially laminated on a heat-resistant base material, wherein the release layer has a glass transition temperature of 50 to 100 ° C. and a molecular weight of 20.
Thermal transfer characterized in that the recording layer contains at least an acrylic resin having a melting point of from 60 to 100 ° C. and a melting viscosity at the melting point of 10,000 poise or less and a coloring agent. recoding media. 2. The release layer has a glass transition temperature of 50 to 100 ° C.
2. The thermal transfer recording medium according to claim 1, wherein a polyester resin having a molecular weight in the range of 2,000 to 20,000 is added in an amount of 0 to 60 parts by weight based on 100 parts by weight of the total solid content of the release layer.