JPH0768958A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium in which contact bonding stain of a paper to be transferred is prevented without deteriorating transfer property. CONSTITUTION:A thermal transfer recording medium is constituted by providing an untransferring layer consisting of polyamide resin and/or urethane resin on base material and providing a mold release layer containing waxy substance as a main component thereon and furthermore providing a coloring transfer layer consisting of both a vehicle formed of heat melting resin as an essential component and a coloring agent thereon.

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 in which fouling due to pressure bonding is prevented.

[0002]

2. Description of the Related Art Conventionally, a vehicle containing a heat-meltable resin as a main component and a colorant are formed on a substrate such as a polyester film via a wax-based release layer. A thermal transfer recording medium provided with a colored transfer layer is known. The printing obtained from this thermal transfer recording medium has excellent scratch resistance, and is therefore preferably used for bar code printing and the like.

However, the conventional thermal transfer recording medium has the following problems.

That is, when the transfer paper and the thermal transfer recording medium are superposed on the platen in the thermal transfer printer and the print head is left pressed for a long time on the platen,
This is a phenomenon in which the colored transfer layer in the portion where the print head is pressed is transferred to the transfer paper, and the transfer paper is soiled (this phenomenon is pressure-bonding soiling).

In order to improve the adhesiveness of the colored transfer layer to the transfer paper in the above-mentioned thermal transfer recording medium, pressure-bonding stains have a strong adhesive property such as ethylene-vinyl acetate copolymer as the heat-melting resin. It is caused by that.

The above-mentioned long-term pressure contact condition is likely to occur in a line printer. That is, in a normal line printer, the print head is always in pressure contact with the platen, and therefore, when the time from the end of printing until the start of the next printing is long, pressure-bonding stains occur.

In view of the above points, an object of the present invention is to provide a thermal transfer recording medium which does not cause transfer smearing and does not cause pressure smearing.

[0008]

According to the present invention, a non-transfer layer comprising a polyamide resin and / or a urethane resin is provided on a substrate, and a release layer containing a wax-like substance as a main component is provided thereon. The present invention also relates to a thermal transfer recording medium having thereon a colored transfer layer comprising a vehicle containing a heat-meltable resin as an essential component and a colorant.

[0009]

[Operations and Examples] With the structure in which the specific non-transfer layer is provided between the base material and the release layer, the adhesive force between the non-transfer layer and the release layer is a colored transfer layer when not heated. It becomes larger than the adhesive force between the transfer paper and the transfer paper (of course, the adhesive force between the substrate and the non-transfer layer, the adhesive force between the release layer and the colored transfer layer, and the non-transfer layer and the release layer). The internal cohesive force of the layer and the color transfer layer is larger than the adhesive force between the color transfer layer and the transfer target paper), and the color transfer layer may transfer to the transfer target paper even after a long press contact condition as described above. There is no crimping stain.

At the time of printing, the release layer at the heated portion is separated in the layer, so that the colored transfer layer is transferred to the transfer paper, and the transfer is performed in the same manner as in a normal thermal transfer recording medium.

Further, in the thermal transfer recording medium of the present invention, since the adhesive force between the release layer and the substrate (non-transfer layer) is large, color transfer is caused by contact with other members when the thermal transfer recording medium is running. There is no phenomenon of layer falling off (generally called ink powder drop). This powder drop occurs even without the pressure contact state for a long time as described above, and also occurs in the serial printer. Therefore, the thermal transfer recording medium of the present invention can be preferably used in a serial printer.

As a means for increasing the adhesive force between the release layer and the base material, it is conceivable to blend a resin into the release layer. Then, at the time of printing, the release layer and the base material are separated from each other. The adhesive force, the internal cohesive force in the release layer, and the adhesive force between the release layer and the colored transfer layer are larger than the adhesive force between the colored transfer layer and the transfer paper, and the releasability becomes poor.

The colored transfer layer in which the resin is the main component of the vehicle is usually formed by a solvent coating method. However, when the colored transfer layer is coated with a coating after the release layer is formed on the substrate, the wax becomes a solvent. Although it is difficult to dissolve, it is difficult to incorporate the resin into the release layer because the resin is easily dissolved.

Next, the present invention will be described in detail.

In the present invention, a non-transfer layer made of a polyamide resin and / or a urethane resin is interposed between the base material and the release layer.

Polyamide resin and urethane resin have a large adhesive force to a substrate such as a polyester film, and a large adhesive force to a release layer containing a wax-like substance as a main component, so that no pressure-bonding stain and ink powder drop occur. .

However, since polyamide resins and urethane resins generally have a large adhesive force, in the step of forming the release layer after forming the non-transfer layer made of these resins, the non-transfer layer has the adhesive property, so that the coater is used. However, there is a possibility that there will be a problem in that it adheres to the roll and the coating work becomes difficult. In such a case, it is preferable to control the adhesiveness of the polyamide resin and urethane resin by using a filler together.

The polyamide resin used in the non-transfer layer in the present invention is not particularly limited as long as it is an ordinary thermoplastic polyamide resin having a relatively low molecular weight.
Particularly, a polycondensation product of dimer acid and polyamine and diamine is preferable.

The urethane resin used in the non-transfer layer in the present invention is not particularly limited as long as it is a urethane resin having ordinary flexibility, and examples thereof include polyester diol, polyether diol and polyester polyether diol. Diol component and tolylene diisocyanate, diphenylmethane diisocyanate,
Those obtained by reacting with a diisocyanate component such as hexamethylene diisocyanate and isophorone diisocyanate, and having an isocyanate group at both ends obtained by reacting the above polyester diol, polyether diol, polyester polyether diol with the above diisocyanate component Those obtained by reacting a prepolymer with a chain extender (diamine such as hexamethylenediamine, 4,4'-diaminodiphenylmethane, isophoronediamine, diol such as ethylene glycol, propylene glycol, and 1,4-butanediol) can give.

Among the urethane resins, polyester-based urethane resins have particularly good adhesion to substrates such as polyester films, while polyether-based urethane resins have particularly good adhesion to wax-like substances.
Therefore, in the present invention, it is more preferable to use a mixture of a polyester-based urethane resin and a polyether-based urethane resin or a polyester polyether-based urethane resin, and to improve the adhesiveness with the base material and the adhesiveness with the release layer, It is possible to more completely prevent pressure-bonding stains and ink powder drop. When using these urethane resins, the ratio of polyester-based urethane resin and polyether-based urethane resin (in the case of polyester polyether urethane resin, the ratio of polyester diol and polyether diol) should be adjusted in order to obtain good combined effect. Polyester-based urethane resin 100 parts (parts by weight, hereinafter the same applies to polyether-based urethane resin 10 to 300 parts, particularly 50 to 200 parts, preferably 70 to 120 parts.

Particles such as carbon black, titanium oxide, and silica can be used as the filler to be added to the non-transfer layer, if necessary. When a filler is added to the non-transfer layer, its content is 5 to 85% (weight%, the same applies below),
It is preferably 15 to 35% of the total. If the content of the filler is less than the above range, the tackiness of the resin cannot be sufficiently controlled, while if it is more than the above range, the adhesiveness between the base material and the release layer tends to be poor due to the decrease of the resin component.

If desired, the non-transfer layer may further contain an auxiliary agent such as a dispersant. The non-transfer layer may be crosslinked with an isocyanate compound or the like at a low crosslink density.

The non-transfer layer preferably has a softening temperature of 80 ° C. or higher, which is higher than the softening temperature of the colored transfer layer.

The non-transfer layer is preferably as thin as possible from the viewpoint of heat conduction and the like, and usually has a coating amount (solid coating amount, hereinafter the same) of 0.1 to ² g / m ² , particularly 0.3.
It is preferable to set it to 1.0 g / m ² .

The non-transfer layer is formed by applying and drying a coating solution prepared by dissolving and dispersing the above polyamide resin and / or urethane resin, a filler if necessary, and other compounding agents in an appropriate solvent. it can.

As the release layer in the present invention, an ordinary heat-meltable release layer containing a waxy substance as a main component can be used without particular limitation.

Examples of the wax-like substance include natural waxes such as wood wax, beeswax, carnauba wax, candelilla wax, montan wax, ceresin wax; petroleum waxes such as paraffin wax and microcrystalline wax; oxidized wax, ester. Synthetic waxes such as wax, polyethylene wax, Fischer-Tropsch wax, α-olefin-maleic anhydride copolymer wax; higher fatty acids such as myristic acid, palmitic acid, stearic acid, behenic acid; higher aliphatic alcohols such as stearyl alcohol and docosanol Higher fatty acid monoglyceride, sucrose fatty acid ester, sorbitan fatty acid ester, and other esters; stearic acid amide, oleylamide, and other amides and bisamides One or more, such as can be used.

Among these, the softening point is 60 to 90 ° C. and the penetration is 2
Hereinafter, those having a viscosity of 5 to 100 cps (90 ° C) are preferable,
Examples of such waxy substances include candelilla wax, carnauba wax, montan wax,
Examples include Fischer-Tropsch wax, paraffin wax, polyethylene wax and the like.

In the release layer, in addition to the waxy substance,
If necessary, fillers, oils, fatty acids, etc. may be added.

The release layer may be formed by a hot melt coating method, or a solvent solution of a wax-like substance,
It may be formed by applying a coating liquid composed of a dispersion liquid, an emulsion or the like on a substrate and drying it.

The coating amount of the release layer is preferably in the range of 0.1 to 4 g / m ² . If the coating amount is less than the above range, the peeling effect is poor, and if it is more than the above range, thermal diffusion becomes large, which is not preferable.

As the color transfer layer in the present invention, a conventional color transfer layer comprising a colorant and a vehicle containing a heat-meltable resin as an essential component can be used without particular limitation.

The vehicle may be, for example, one containing 40% or more of a heat-meltable resin, and optionally blended with a wax-like substance, a dispersant, an extender pigment and the like. When an image having excellent scratch resistance is desired, the content of the heat-meltable resin in the vehicle is preferably 60% or more. In this case, an extender pigment is blended in order to improve transferability. Is good.

The softening point of the colored transfer layer is usually about 50 to 170 ° C.

Examples of the heat-fusible resin include olefin copolymer resins such as ethylene-vinyl acetate copolymer and ethylene-acrylic ester copolymer, polyamide resin, polyester resin, epoxy resin, polyurethane resin. Resin, acrylic resin, vinyl chloride resin,
Cellulose resin, vinyl alcohol resin, petroleum resin, phenol resin, styrene resin, vinyl acetate resin, natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber and other elastomers, polyisobutylene, polybutene, etc. One type or two or more types can be used.

As the wax-like substance, those exemplified for the release layer can be used.

As the colorant, any of those conventionally used as a colorant for this type of heat-meltable ink can be used.
Various organic pigments and dyes are appropriately used. The content of the colorant in the ink layer is usually about 10 to 50%.

The coating amount of the colored transfer layer is usually 0.5 to 6 g / m 2.
² is appropriate.

The substrate in the present invention is generally a polyester film such as a polyethylene terephthalate film, a polyethylene naphthalate film, a polyarylate film, a polycarbonate film, a polyamide film, an aramid film, and other films for substrates of ink ribbons of this type. Various types of plastic films used can be used. The thickness of the base material is about 1 to 10 μm from the viewpoint of improving heat conduction, especially 2 to 7
About μm is preferable.

When the above-mentioned plastic film is used as a substrate, a silicone resin, a fluororesin, a nitrocellulose resin, or a silicone-modified urethane resin modified by these, for example, is formed on the back surface (the surface which is in contact with the heating head). A conventionally known stick-preventing layer made of various heat-resistant resins such as silicone-modified acrylic resin or a mixture of these heat-resistant resins with a lubricant may be provided.

Next, the present invention will be described with reference to examples.

Examples 1 to 5 and Comparative Examples 1 to 2 On the surface of a polyethylene terephthalate film having a thickness of 6 μm and having a silicone-modified acrylic resin layer having a thickness of 0.1 μm formed on the back surface, the non-transfer layer coating shown in Table 1 was applied. The working solution was applied and dried at 60 ° C. to form a non-transfer layer having a coating amount of 0.8 g / m ² . In Comparative Example 2, the non-transfer layer was not formed.

[0043]

[Table 1]

Next, paraffin wax was applied onto the non-transfer layer (in the case of Comparative Example 2, the base film) to form a release layer having a coating amount of 1.0 g / m ² . Then, a coating solution for coloring transfer layer having the following formulation was applied onto the release layer and dried to form a coloring transfer layer having a coating amount of 2.0 g / m ² and a softening point of 80 ° C.

Component Part Ethylene-vinyl acetate copolymer 6.8 Petroleum resin 1.4 Carbon black 1.6 Toluene 90 In Examples 1 to 4, there was no problem in the step of forming the release layer on the non-transfer layer. However, in Example 5, the non-transfer layer tended to stick to the rotor roll.

The following tests were conducted on each of the thermographic recording media obtained above. The results are shown in Table 2.

(1) Pressure-bonded dirt Between two pressing plates (temperature control of lower plate to 30 ° C. and upper plate to 40 ° C.), thermal transfer recording medium and paper (Beck smoothness 20
00 seconds coated paper) and a paper bottom, so that the thermal transfer recording medium is in the upper, and pigmented transfer layer of the thermal transfer recording medium is sandwiched what superposed in contact with the paper, 54kg / cm ²
After holding for 30 seconds under the load, the thermal transfer recording medium was peeled off from the paper to examine how much the colored transfer layer was transferred to the paper, and the pressure-bonding stain was evaluated on the basis of the following criteria in 5 grades.

1 ... 99% or more of the crimped part is transferred 2 ... 98-50% of the crimped part is transferred 3 ... 49-25% of the crimped part is transferred 4 ... 24-1% of the crimped part is transferred 5 ... Crimped part (2) Transferability Using each of the above-mentioned thermal transfer recording media, printing was performed on high quality paper (Beck smoothness of 200 seconds) at a printing speed of 152 mm / sec with a commercially available printer for thermal transfer barcode. The printing pattern was a mixture of ANK, barcode, graphic, and solid printing. The printing results were evaluated according to the following criteria.

1 ... Printing is not possible without transfer. 2 ... Transfer occurs, but ANK cannot be read and bar code cannot be read. 3 ... ANK can be read, but bar code cannot be read. 4 ... Good printing can be obtained with ANK, bar code, and solid printing, but graphics have defects. 5: ANK, barcode, graphic, and solid printing can be printed satisfactorily.

[0050]

[Table 2]

[0051]

According to the thermal transfer recording medium of the present invention, pressure-sensitive contamination of the transfer paper can be prevented without lowering the transferability.

Claims (3)

[Claims] 1. A non-transfer layer comprising a polyamide resin and / or a urethane resin is provided on a substrate, a release layer containing a wax-like substance as a main component is provided thereon, and a heat-melting property is further provided thereon. A thermal transfer recording medium provided with a colored transfer layer comprising a vehicle containing a resin as an essential component and a colorant. 2. The thermal transfer according to claim 1, wherein the urethane resin comprises a mixture or copolymer of a polyester urethane resin and a polyether urethane resin, and the ratio of the latter is 10 to 300 parts by weight relative to the former 100 parts by weight. recoding media. 3. The thermal transfer recording medium according to claim 1, wherein the non-transfer layer contains a filler in an amount of 5 to 85% by weight.