JP2918909B2 - Many times thermal transfer media - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer medium that prevents background contamination during multiple printing.

2. Description of the Related Art Conventionally, various non-impact recording methods have been developed. One of the thermal transfer recording methods is a word processor, which has low noise and can be recorded on plain paper, and has a compact device and good storability. , Facsimile, label printer, ticketing machine and the like.

Conventionally, a thermal transfer medium used for such thermal transfer recording is of a one-time type in which an ink layer formed of a thermal fusible ink comprising a thermal fusible binder material and a colorant is provided on a base film. In this case, the ink layer at the printing location was chipped.

In order to reduce the running cost of this one-time type thermal transfer medium, various thermal transfer media capable of performing thermal transfer many times with the same medium have been proposed in recent years.

Problems to be Solved by the Invention However, since these multi-time thermal transfer media contain a large amount of colorant, marginal portions of the recording paper other than the printing portion are slightly stained with ink, that is, a so-called background stain is easily generated. There is. In addition, in order to prevent such background contamination, a method has been proposed in which a large amount of resin is contained in the hot-melt ink to maintain the printing density. However, when the amount of the ink component is reduced, the resin tends to stick to recording paper. However, there are drawbacks such as causing running failure. As described above, the conventionally proposed multiple-time thermal transfer medium cannot meet the user's wishes.

The purpose of the present invention is to remedy these disadvantages of the prior art,
An object of the present invention is to obtain a thermal transfer medium that can be printed many times without deteriorating the print quality and can obtain clear print quality without background contamination.

Means for Solving the Problems The present invention provides a thermal transfer medium, a multi-time thermal transfer medium comprising a heat-resistant porous resin layer impregnated with a hot-melt ink on a substrate, wherein the hot-melt ink is It is composed of a heat-meltable component mainly composed of polyethylene wax and a resin-coated pigment, or a composition in which a spherical filler is added thereto, and the resin coating the pigment is a polyamide resin, a phenol resin, a styrene resin, or a polyester resin. It has been found that the above object can be achieved by using one or two or more kinds selected from the above, and the present invention has been completed.

The hot-melt component is mainly composed of polyethylene wax, but a wax having good dispersibility such as polyethylene oxide wax, ester wax, and α-olefin maleic anhydride may be used in combination to enhance the dispersibility of the colorant. The amount used is desirably in the range of 50 to 95% by weight of the ink component. If the amount is more than this, the colorant is easily peeled off, and if it is less than this, the dispersibility becomes poor.

The resin for coating the pigment is a polyamide resin, a phenol resin, a styrene resin, a polyester resin, or the like, and has a softening point of 120 ° C. or higher because it is not melted during ink preparation. There is a risk of melting.

The resin that forms the heat-resistant porous layer is vinyl chloride,
Vinyl resins such as vinyl chloride / vinylidene chloride copolymers, polyester resins, styrene resins, polyamide resins and the like.

The resin-coated pigment is prepared by charging the pigment into a solution of the coating resin, dispersing the pigment uniformly, evaporating the solvent, drying, and cooling and pulverizing.

The fine-particle heat-meltable ink is obtained by charging a resin-coated pigment into the heat-meltable component, heating and finely dispersing the pigment, and then cooling and pulverizing to obtain fine particles of 0.1 to 5 μm.

The substrate is a film of polyester, polysulfone, polyacetal, polyimide, or the like, and preferably has a thickness of 10 μm or less. If necessary, a stick prevention layer formed of a heat-resistant resin may be provided on the surface of the opposite side of the ink layer from the thermal head.

 The thermal transfer medium of the present invention is manufactured as follows.

The resin that forms the porous layer is dissolved in a mixed solvent of a poor solvent and a poor solvent, and the fine powder of the hot-melt ink is added therein to 1.0 to 1.8 /
After charging at a ratio of 1.0 and uniformly dispersing, the mixture is applied to a substrate so that the total solid content has a thickness of 3 to 15 μm (preferably 7 to 10 μm), and the solvent is evaporated and dried to produce the product. On this occasion,
The hot-melt ink may be one in which a resin-coated pigment is dispersed in a hot-melt component, or one in which a spherical filler is added thereto.

Function In the thermal transfer medium of the present invention, at the time of transfer recording, both the pigment printed on the recording paper and the pigment remaining on the surface of the transfer medium without printing are coated with the resin.

Therefore, the background stain that is considered to be a thin ink stain on the margin of the recording paper in contact with the pigment by the pigment partially exposed on the coating surface of the base material is obtained by coating the pigment with a resin film as in the present invention. By not exposing the surface, the print quality can be significantly reduced without deteriorating the print quality.

Furthermore, when a spherical filler is added, the coated surface becomes uneven, so that the transfer medium and the transfer receiving paper are changed from surface contact to point contact, so that the contact area is reduced and the background stain is more effectively prevented. .

With such a thermal transfer medium, clear printing with almost no background stain can be obtained many times without deteriorating the printing quality.

Embodiment Next, an embodiment of the present invention will be described. (The number of each component in each of the examples and comparative examples is hereinafter referred to as “parts by weight”.) The pigment is charged into the resin solution according to the following formulation, kneaded, the solvent is evaporated, dried, and cooled and pulverized. Thus, a resin-coated pigment was obtained.

Carbon black (MA-11, manufactured by Mitsubishi Kasei Co., Ltd.) 23.5 Phenolic resin (Tamanol 352, manufactured by Arakawa Chemical Co., Ltd.) 5.8 Toluene 70.4 Activator (Plainact ALM, manufactured by Ajinomoto Co., Inc.) 0.3 100 The pigment thus obtained was put into the following hot-melt component, heated and dispersed, and then cooled and pulverized to obtain a fine-particle hot-melt ink.

Resin-coated pigment 18.6 Polyethylene wax (Nippon Seiro Co., Ltd., Vysen 0252C) 64.0 Dispersant (Mitsubishi Kasei Corp., PA-30L) 16.0 Dye (Orient Chemical Co., Ltd., Nigrosine Ex) 1.4 100 The hot-melt ink adjusted as described above was poured into a solution in which the following resin was dissolved in the following mixed solvent, and after being uniformly dispersed, a thickness of 8 μm was formed on a polyester film substrate.
And dried in hot air at 90 ° C. to obtain a black thermal transfer medium.

Heat-meltable ink 12.5 Polyester resin (manufactured by Toyobo Co., Ltd., Byron # 200) 12.5 Ethyl acetate 37.4 Toluene 37.3 Activator (manufactured by Ajinomoto Co., Inc., plainact ALM) 0.3 100 And a thermal transfer medium was obtained in the same manner as in Example 1, except that the parts by weight of each component were changed as described below.

Hot-melt ink 10.4 Polyester resin (Toyobo Co., Byron # 200) 10.4 Spherical filler (Nippon Shokubai Chemical Co., Ltd., Eposter M-60) 4.1 Ethyl acetate 37.4 Toluene 37.4 Activator (Ajinomoto Co., Ltd.) Plain act ALM) 0.3 100 When the thermal transfer media of Examples 1 and 2 obtained in this way were mounted on a normal thermal printer and printing was performed many times, there was no extreme decrease in density up to the fifth time. Good printing with almost no stain was obtained.

 Next, a comparative example will be described.

Comparative Example 1 The following heat-fusible component and colorant were heated and dispersed, and then cooled and pulverized to obtain a fine-particle heat-fusible ink.

Polyethylene wax 62.0 (Nippon Seiro Co., Ltd., Vicene 0252C) Dispersant (Mitsubishi Kasei Corp., PA-30L) 15.0 Ethylene / vinyl acetate copolymer resin (Mitsui DuPont Polychemical Co., Ltd., EVA410) 2.0 Carbon black (MA-11, manufactured by Mitsubishi Kasei Co., Ltd.) 18.6 Dye (Nigrosine Ex, manufactured by Orient Chemical Co., Ltd.) 1.4 100 The above-prepared hot-melt ink was prepared by dissolving the following resin in the following mixed solvent. The solution was poured into a dissolving solution, uniformly dispersed, coated on a polyester film substrate to a thickness of 8 μm, and dried in hot air at 90 ° C. to obtain a thermal transfer medium.

12.5 Resin (Toyobo Co., Ltd., Byron # 200) 12.5 Ethyl acetate 37.4 Toluene 37.3 Activator (Ajinomoto Co., Ltd., Plainact ALM) 0.3 100 The thus obtained thermal transfer medium of Comparative Example 1 is usually used. When printing was performed many times with the printer mounted on a thermal printer, clear printing could not be obtained due to soiling of the background.

Advantageous Effects of the Invention According to the present invention, by obtaining the above-described thermal transfer medium, it is possible to obtain a good number of good prints with no background stain and little density reduction.

Claims (1)

(57) [Claims] In a multiple-time thermal transfer medium comprising a heat-resistant porous resin layer impregnated with a hot-melt ink on a substrate, the hot-melt ink comprises a heat-meltable component mainly composed of polyethylene wax. And a resin-coated pigment, or a resin to which a spherical filler is added, and the resin for coating the pigment is one or two selected from a polyamide resin, a phenol resin, a styrene resin, and a polyester resin.
A multi-time thermal transfer medium, characterized in that it is at least one species.