JPH02145395A - Thermal transfer sheet and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve slipping properties and heat resistance by providing a transfer ink layer on one face of a base film, and providing a back layer made of specific crosslinked resin on the other side face to form a thermal transfer sheet. CONSTITUTION:A transfer ink layer melted by heating is laminated on one face of a base film, and a back layer made of crosslinking resin of reactive product of reactive polysiloxane compound, reactive resin and polyisocyanate on the other side face of a base film in contact with a thermal head to form a thermal transfer sheet. When the back layer is formed of the crosslinking resin obtained by the reactive polysiloxane compound, reactive resin and polyisocyanate, slipping properties and heat resistance can be compatible without using a large amount of mold release agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal transfer sheet and a method for manufacturing the same, and more particularly to a novel thermal transfer sheet having a back layer with excellent slip properties and heat resistance.

(Prior art and its problems) Conventionally, when printing output prints from computers or word processors using a thermal transfer method, a thermal transfer sheet with a heat-melting ink layer provided on one side of a base film has been used. .

The above conventional thermal transfer sheet has a thickness of 1 as a base film.
Using paper such as capacitor paper or paraffin paper with a thickness of 0 to 20 μm, or plastic film such as polyester or cellophane with a thickness of 3 to 20 μm, a layer of heat-melting ink made by mixing coloring agents such as pigments and dyes with wax is applied. It is manufactured by coating.

In addition, when using heat-resistant materials such as plastic films as the base film, the thermal head may stick during printing, impairing the peeling and slipping properties of the thermal head, or tearing the base film. A problem occurs.

In order to solve these problems, a method has been proposed in which the back layer is made of a resin with excellent heat resistance.However, it is recommended that the back layer be made of a resin with high heat resistance, that is, a resin that does not soften with the heat of the thermal head. In this case, the problem of adhesion of the thermal head is small, but good slip properties of the thermal head cannot be obtained.

For this reason, a method has been proposed in which silicone oil is included in the back layer made of a highly heat-resistant resin, but with this method, the silicone oil floats on the surface of the back layer, causing problems such as blocking of thermal transfer and dust adhesion. This has caused problems such as thermal head failure and printing defects.

Furthermore, as a method to solve the above-mentioned problems, a method has been proposed in which the back layer is formed of a silicone-modified polyurethane resin (for example, Japanese Patent Laid-Open Nos. 184717-1986 and 62-1982).
However, since the modified resin is essentially a linear thermoplastic resin, it exhibits good slip properties, but it softens or melts due to the heat of the thermal head.
It is unsatisfactory in terms of heat resistance to protect the base film.

Therefore, an object of the present invention is to provide a novel thermal transfer sheet having a back layer that exhibits both slip properties and heat resistance without using a large amount of a release agent.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a thermal transfer sheet comprising a transfer ink layer that is melted by heating on one side of a base film and a back layer on the other side of the base film that is in contact with a thermal head. The thermal transfer sheet is characterized in that it is formed from a crosslinked resin obtained from a reactive polysiloxane compound, a reactive resin, and a polyisocyanate, and a method for producing the same.

(Function) By forming the back layer from a crosslinked resin obtained from a reactive polysiloxane compound, a reactive resin, and a polyisocyanate, a back surface that has both slip properties and heat resistance can be created without using a large amount of mold release agent. A novel thermal transfer sheet having layers is provided.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to preferred embodiments.

As the base film used in the present invention, the same base film used in conventional thermal transfer sheets can be used as is, and other films can also be used, and there are no particular limitations.

Specific examples of preferred base films include polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride,
Polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber,
Examples include plastics such as ionomers, papers such as condenser paper and paraffin paper, nonwoven fabrics, and base films made of composites of these materials.

The thickness of this base film can be changed as appropriate depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 25 μm.

The back layer, which primarily characterizes the invention, is formed from a crosslinked resin (n·0 to 200) obtained from a reactive polysiloxane compound, a reactive resin and a polyisocyanate.

The reactive siloxane compound used in the present invention (3) has a hydroxyl group, an amino group, an epoxy group, a carboxyl group, or a thio group at the end or side chain of the siloxane segment (1=1 to 10, m-10 to 200, n-1 to 5) It is a compound having a reactive group such as an alcohol group, and the following compounds are preferred, and particularly preferred are alcohol-modified or a(rho 1 to 200, R, lower alkyl) or mino-modified polysiloxane. be.

(2) Amino-modified polysiloxane (1) Alcohol-modified polysiloxane (m-1 to lOl, 2 to 1O5 R-CH, or 0CTo) (Rho 1 to 200) (0 to 10゜n, 2 to 10 , R-CH3 or OCH+) (m-1 to 1O1 n-2 to 10) Shi■3 Shi■3 (IIl-IO to 200) (n・2 to 10) (m-1 to 10, n-2 to 10) (n -1 to 200) (Branch point 2 to 3, R-lower alkyl group, 1-2 to 200, m = 2 to 200, n = 2 to 200) (Branch point 2 to 3, R・Lower alkyl group, 1-2 to 200, m-2 to 200, n=2 to 200) (r+-1 to 200°R・lower alkyl group) (3) Epoxy-modified polysiloxane (n-1 to 10) (n=1 to 200) (+++-1 to 10, n-2 to 10) (4) Mercapto-modified polysiloxane (5) Carboxyl-modified polysiloxane (+++-1 to 101n・2 to 10) (mml to 1O1n・2 to 10) (n・2 to 1G) (n=1 to 200) (branch point・2 to 3.R・lower alkyl group, 1-2 to 200%ts-2 to 200, n=2 to 200
) (branch point 2 to 3, R lower alkyl group, 1-2 to 200, m" 2 to 200, n-2 to 2
00) (n-1 to 200, R-lower alkyl group)
(n=1 to 200, R-lower alkyl group) Examples of the reactive resin used in the present invention include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate,
Cellulose resins such as nitrate (tJ), vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone, polyacrylamide, polyester resins, etc., which contain hydroxyl groups, carboxyl groups, etc. Among these, those having three or more hydroxyl groups such as cellulose, acetal, butyral, polyester, and polyurethane are preferred.

As the polyisocyanate used in the present invention, general polyisocyanates can be used, but preferred are polyurethane polyisocyanates having a relatively high molecular weight and reacted with polyisocyanate dimers, trimers, or polyol compounds. .

These polyisocyanates are, for example, bamboonate (
(manufactured by Narita Pharmaceutical), Parnock (manufactured by Dainippon Ink Chemical), Coronate (manufactured by Nippon Polyurethane), Duranate (manufactured by Asahi Kasei Kogyo), Dismodur (manufactured by Bayer), Polyisocyanate MDI, TDI (manufactured by Miso Layer Ink), Crossnate (manufactured by Moriso Ink), (manufactured by Dainichiseika Kogyo Co., Ltd.), etc., and can be used in the present invention. In the present invention, it is preferable to use at least a portion of trifunctional or higher functional polyisocyanate.

The amounts of the reactive polyol compound, reactive resin, and polyisocyanate used as described above are such that the formed back layer has a crosslinked structure.In order to obtain particularly high heat resistance, the total amount of the three should be Our polyisocyanate is 10 times 1
% or more, preferably 20 to 70% by weight. If the amount of polyisocyanate used is less than 10% by weight, the heat resistance of the back layer will be insufficient, and the back layer will be
It is difficult to make the layer thinner than m, making it difficult to improve sensitivity. In addition, it is preferable to use the reactive polysiloxane compound in a proportion that accounts for 5 to 50% by weight of the total of the three components; if the amount used is too small, sufficient slip properties cannot be obtained, and if the amount is too large, the coating may deteriorate. This is not preferred because it lacks strength and adhesion to the base film. Furthermore, if the amount of reactive resin used is small, the formed film will become brittle, so it is preferable to use the reactive resin in a proportion that accounts for 10% by weight or more of the total weight of the three linings.

In addition, in order to improve the heat resistance of the back layer, hydrotalcite DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.) was used as a heat resistant agent.
Talc Micro Ace-1 (Japan Talc Group), Teflon Rubron Shi-2 (Daikin Industries), Graphite Fluoride 5CF-10 (Nisei Chemical Industries), Graphite AT40S (
Oriental Sangyo) or silica, calcium carbonate,
Fine particles of precipitated barium sulfate, urea resin crosslinked powder, acrylic resin crosslinked powder, silicone resin powder, wood flour, molybdenum disulfide, boron nitride, and the like can be included.

For the back layer, prepare a coating solution by dissolving or dispersing the above materials in a suitable solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc., and apply this coating solution using a gravure coater, roll coater, wire bar, etc. It is formed by coating by a conventional coating method, and reacting the reactive polysiloxane, the reactive resin, and the polyisocyanate during heat drying after coating to form a resin layer with a crosslinked structure. The crosslinked structure is sufficiently formed by treatment at a temperature of 50 to 100°C for several hours to several days. Of course, a curing catalyst or the like can be used in this reaction.

The coating amount, that is, the thickness of the back layer is also important, and in the present invention, the solid content is 1.0 g/m or less, preferably 0.1 g/m'' or less.
A back layer having sufficient performance can be formed with a thickness of 0.5 g/m''.

It is also effective to form a brimer layer made of polyurethane resin or the like prior to forming the above-mentioned back layer. Incidentally, in the present invention, conventionally known lubricants and mold release agents can be included within the range that does not impede the object of the present invention.

In the present invention, a heat-melting ink layer is further formed on the other surface of the base film using an ink containing necessary materials.

The ink for forming the hot-melt ink layer used in the present invention comprises a colorant and a vehicle, and may further contain various additives as necessary.

The coloring agent is preferably an organic or inorganic pigment or dye that has good properties as a recording material, for example, one that has sufficient color density and does not discolor or fade due to light, heat, temperature, etc.

Alternatively, it may be a substance that is colorless when not heated but develops color when heated, or a substance that develops color when it comes into contact with something coated on the transfer target. In addition to the colorants forming cyan, magenta, yellow, and black, colorants of various other colors can also be used.

The vehicle is mainly composed of wax, and mixtures of wax with drying oil, resin, mineral oil, cellulose, rubber conductors, etc. are used.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. In addition, various waxes such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolatum, assorted waxes, fatty acid esters, fatty acid amides, etc. are used. It will be done.

Further, in order to provide the hot-melt ink layer with good thermal conductivity and melt transferability, a thermally conductive substance can be blended into the hot-melt ink. Examples of this substance include carbonaceous substances such as carbon black, aluminum, copper, tin oxide, and molybdenum disulfide.

In addition to hot melt coating, methods for forming a hot melt ink layer directly or indirectly on a base film include:
Examples include hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods of applying the ink. The thickness of the ink layer formed should be determined to balance the required concentration and thermal sensitivity, and is in the range of 0.1 to 30 μm, preferably in the range of 1 to 20 μm.

In the present invention, a surface layer can be further formed on the ink layer. The surface layer forms a part of the transfer film, forms the surface in contact with the transfer paper, seals the printed area of the transfer paper during transfer, prevents scumming, and prevents the ink layer from being covered. It has the function of improving adhesion to transfer paper.

The wax used to form the surface layer is the same substance as the wax used in the hot-melt ink layer described above.

The surface layer made of the wax is formed by coating and cooling a wax melt, coating and drying an organic solvent solution containing the wax, coating and drying an aqueous dispersion containing particles of the wax, and the like.

The coating of the surface layer, as well as the formation of the ink layer, can also be done by various techniques. In the present invention, the thickness of this layer is preferably 0.1μ so as not to cause insufficient sensitivity even when printing energy is low as in high-speed printers.
m or more and less than 5 μm.

It is recommended that an appropriate amount of extender pigment be added to the surface layer. This is because bleeding and trailing of printed characters can be better prevented.

Thermal transfer images generally have glossy and beautiful prints, but the documents may become difficult to read, so matte prints are sometimes desirable. In such a case, for example, as proposed by the applicant (Japanese Patent Application No. 58-208306), an inorganic pigment such as silica, calcium carbonate, etc. is dispersed in a suitable solvent on a base film. It is preferable to form a thermal transfer sheet by coating a matte layer and then coating a heat-melting ink layer. Alternatively, the base film itself may be matted and used (the technique of Japanese Patent Application No. 58-208307, also proposed by the applicant).
.

It goes without saying that the present invention can be applied to thermal transfer sheets for color printing, so multicolor thermal transfer sheets are also included within the scope of the present invention.

(Effects) According to the present invention as described above, by forming the back layer from a crosslinked resin obtained from a reactive polysiloxane compound, a reactive resin, and a polyisocyanate, it is possible to A novel thermal transfer sheet having a back layer having both slip properties and heat resistance is provided.

(Example) Hereinafter, the present invention will be explained in more detail by giving Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 1 - Polyvinyl butyral resin (Eslec BX-1, manufactured by Shin-Etsu Chemical) 26.6 parts Siloxane diol having the following structure (X-22-160C1 manufactured by Shin-Etsu Chemical)
20.0 parts polyisocyanate (Takenate ^-3, manufactured by Narita Pharmaceutical Co., Ltd.)
53.3 parts toluene/methyl ethyl ketone (1/
1) An ink composition for the back layer was prepared by thoroughly kneading the above composition in an amount such that the solid content was 12.0% (n is a value such that the average molecular weight was 5,600), and a thickness of 6.0 μm was prepared. and 4.5 μm polyester film (
After applying Myabah #4 to one surface of the product "Lumirror" (manufactured by Bunshishi ■) at a coating weight of 10.5 g/rn'' (solid content), it was dried with warm air.The obtained film was Further, a heat curing treatment was performed in an oven at 65° C. for 6 days to form a back layer.

Separately, transfer the transfer ink composition with the following composition into a blade kneader.
The mixture was kneaded for 6 hours while heating to 90°C.

Nbarafin wax 10 parts Carnauba wax 10 parts Polybutene (VH-1
00, manufactured by Nippon Oil ■) 1 part carbon black (Geest 3, manufactured by Tokai Electrode ■)
2 parts The above ink composition is heated at a temperature of 100°C and applied to the other surface of the above base film using a hot melt roll coating method at a coating amount of about 5.0 g/rn' for thermal transfer. An ink layer was formed to obtain a thermal transfer sheet of the present invention.

Example 2 In place of the reactive polysiloxane of Example 1, a reactive polysiloxane with the following structure (X-22-161G, Shin-Etsu Chemical Co., Ltd.
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1, except that the same method as in Example 1 was used.

(n is a value that gives an average molecular weight of 3,880) Example 3 The procedure was the same as in Example 1 except that the back layer was formed using the following composition instead of the back layer of Example 1. A thermal transfer sheet of the present invention was obtained.

' 1 Ink polyvinyl butyral resin (S-LEC BX-1, manufactured by Block Chemical @) 19.3 parts siloxane diol (X-22-16011, manufactured by Shin-Etsu Chemical)
20.0 parts fatty acid amide (Aramide HT-P, manufactured by Lion ■)
5.0 parts melamine resin fine particles (Eposter S, manufactured by Nippon Shokubai Chemical Co., Ltd.) 17.0 parts Polyisocyanate (Takenate A-3, manufactured by Narita Pharmaceutical Co., Ltd.)
38.6 parts toluene/methyl ethyl ketone (1/l) Amount to give a solid content of 12.0% Example 4 Except for forming the back layer using the following composition instead of the back layer of Example 1. A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1.

1 part polyvinyl butyral resin (S-LEC BX-1, manufactured by Tanesui Chemical ■) 19.3 parts polysiloxane diol (X-22-160 [], manufactured by Shin-Etsu Chemical ■)
20.0 parts Taruri (Micro Ace L-1, manufactured by Nippon Taruri ■) 5.0 parts Melamine resin fine particles (Eposter S, manufactured by Nippon Shokubai Chemical Industry ■) 17.0 parts Polyisocyanate (Takenate A-3, Narita (manufactured by Yakuhin Kogyo)
38.6 parts amine catalyst (Desmoravid PP1, manufactured by Sumitomo Bayer Urethane) o
, oi part toluene/methyl ethyl ketone (1/l) Amount for solid content to be 12.0% Comparative Example 1 A thermal transfer sheet of a comparative example was prepared in the same manner as in Example 1 except that the back layer was not formed in Example 1. I got it.

Printing was carried out using the thermal transfer sheets of the above Examples and Comparative Examples under the following printing conditions, and the running performance of the head and the state of the thermal transfer sheet after printing were compared, and the results shown in Table 1 below were obtained.

Equipment used: Toshiba simulator equipped with a membrane-type thermal head Printing energy: 1.70 mJ/dot (area per dot is 4 x 10-'crn) Solid printing material: High-quality paper (Sanyo Kokusaku) Manufactured by Valve ■, YP46 version 135KG) 6.Om 4.5 Example 10 0 Example 20 0 Example 3 0 0 Example 4 0 0 Comparative example 1 x x○: Good heat resistance and slip property, no problem none.

×: Sticking, opening, and breakage.

Claims (6)

[Claims] (1) In a thermal transfer sheet that has a transfer ink layer that melts when heated on one side of a base film and a back layer on the other side of the base film that contacts the thermal head, the back layer is reactive. A thermal transfer sheet characterized by being formed from a crosslinked resin obtained from a polysiloxane compound, a reactive resin, and a polyisocyanate. (2) The thermal transfer sheet according to claim 1, wherein at least a part of the reactive resin and/or polyisocyanate has trifunctional or higher functionality. (3) The thermal transfer sheet according to claim 1, wherein the reactive polysiloxane compound is an alcohol- or amine-modified polysiloxane. (4) A method for producing a thermal transfer sheet comprising a transfer ink layer that is melted by heating on one side of a base film, and a back layer on the other side of the base film that is in contact with a thermal head, wherein the back layer A method for producing a thermal transfer sheet, comprising: coating a coating liquid containing a reactive polysiloxane compound, a reactive resin, and a polyisocyanate on a base film and crosslinking the film on the base film. (5) The method for producing a thermal transfer sheet according to claim 4, wherein at least a part of the reactive resin and/or polyisocyanate has trifunctional or higher functionality. (6) The method for producing a thermal transfer sheet according to claim 4, wherein the reactive polysiloxane compound is an alcohol- or amine-modified polysiloxane.