JP2792602B2 - Thermal transfer sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal transfer sheet, and more particularly, to a novel thermal transfer sheet having an excellent heat-resistant slip layer (back layer) made of a specific material.

(Conventional technology and its problems) Conventionally, when printing an output print of a computer or a word processor by a thermal transfer method, a thermal transfer sheet provided with a heat-meltable ink layer on one surface of a base film is used. .

This conventional thermal transfer sheet has a thickness as a base film.
Using a 10 to 20 μm thick paper such as condenser paper or paraffin paper or a 3 to 20 μm thick plastic film such as polyester or cellophane, a wax is mixed with a coloring agent such as a pigment or dye to form a hot-melt ink layer. It is manufactured by coating.

Also, when a heat-sensitive material such as a plastic film is used as the base film, the thermal head sticks (sticks) at the time of printing, and the peeling and slipping property of the thermal head is impaired, or the base film is broken. Or other problems occur.

For this reason, a method of forming a heat-resistant layer made of a thermosetting resin or the like having high heat resistance has been proposed, but this method improves the heat resistance but does not improve the slip property of the thermal head.

In order to improve the slip property, it has been proposed to add a relatively low-melting lubricant such as silicone oil, a low-melting wax, a surfactant, etc. For example, if the manufactured thermal transfer sheet is wound into a roll, there is a problem that the thermal transfer sheet transfers to the ink layer on the opposite side and adversely affects the transferability of the ink layer. In addition, since these lubricants soften or melt during thermal transfer to slide the thermal head, there is a problem that the thermal head is inevitably contaminated.

It has been proposed to use inorganic fine particles such as talc and mica as a lubricant that does not cause such problems. However, in the case of these inorganic lubricants, there is a problem that the thermal head is significantly worn.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to have excellent heat resistance, without contaminating other articles and the thermal head, and without abrasion of the thermal head. Another object of the present invention is to provide a thermal transfer sheet provided with a back layer having a slip property.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention provides a thermal transfer sheet comprising a transfer ink layer which is melted by heating on one surface of a substrate film, and a back layer formed on the other surface of the substrate film in contact with a thermal head. A thermal transfer sheet wherein the layer is formed from a binder and a zinc salt or an aluminum salt of an alkyl phosphate.

(Action) By including a zinc salt or an aluminum salt of an alkyl phosphate as a lubricant in the back layer, it has excellent heat resistance, does not contaminate other articles and the thermal head, and wears the thermal head. Thus, a thermal transfer sheet having excellent slip properties can be provided.

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

As the substrate film used in the present invention, the same substrate film as used in the conventional thermal transfer sheet can be used as it is, and other materials can be used without any particular limitation.

Specific examples of preferred base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chloride rubber, ionomer, etc. Paper, such as plastic film, condenser paper, paraffin paper, and non-woven fabric.
A base film in which these are combined may be used.

The thickness of the substrate film can be appropriately changed depending on the material so that the strength and the thermal conductivity become appropriate, but the thickness is 0.5 to 50 μm, preferably 3 to 10 μm.
m.

The back layer which mainly characterizes the present invention is provided on one surface of the above-mentioned base film, and as the base film, for example, one having relatively excellent heat resistance such as polyethylene terephthalate film is used. preferable.

In the present invention, the back layer is formed from a binder resin, a zinc salt or an aluminum salt of an alkyl phosphate, and other necessary additives.

As the binder resin, for example, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose resin such as nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, Polyvinyl pyrrolidone, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polyacrylamide, vinyl resin such as acrylonitrile-styrene copolymer, polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane, and the like. Among them, cellulosic, acetal,
Butyral-based, acrylic resin-based, acrylonitrile-styrene copolymer-based, polyester-based, polyurethane-based, and the like are preferable, and particularly those having some reactive groups, for example, those having a hydroxyl group are used as a crosslinking agent. It is preferable to use a polyisocyanate or the like together to form a crosslinked resin layer.

The zinc salt or aluminum salt of an alkyl phosphate ester used in the present invention and mainly characterized by the present invention is obtained by substituting an alkali metal salt of an alkyl phosphate ester with a zinc salt or aluminum, and is itself a plastic. Various grades of additives are known from the market and all can be used in the present invention.

The zinc salt or aluminum salt of an alkyl phosphate ester particularly preferred in the present invention has a structural formula Wherein R is an alkyl group having 12 or more carbon atoms such as a cetyl group, a lauryl group, and a stearyl group, particularly a stearyl group, and M is zinc or aluminum. Here, n represents the valence of M.

The amount of the zinc salt or aluminum salt of the alkyl phosphate is preferably in the range of 10 to 150 parts by weight per 100 parts by weight of the binder, and when the amount is less than the above range, sufficient slip properties can be obtained. On the other hand, if it exceeds the above range, the physical strength of the back layer is undesirably reduced.

In the present invention, in forming the back layer from the above-mentioned materials, a heat releasing agent or a lubricant such as a wax, a higher fatty acid amide, an ester, or a surfactant is included as long as the object of the present invention is not hindered. I can do it.

In order to improve the heat resistance of the back layer, hydrotalcite DHT-4A (manufactured by Kyowa Chemical Industry),
Talc Micro Ace L-1 (manufactured by Nippon Talc), Teflon Lubron L-2 (manufactured by Daikin Industries), graphite fluoride
SCP-10 (manufactured by Sanbo Chemical), graphite AT407S (manufactured by Oriental Industries) or silica, calcium carbonate, precipitated barium sulfate, urea resin crosslinked powder, styrene / acrylic resin crosslinked powder, amino resin crosslinked powder, silicone powder, wood powder And fine particles of molybdenum disulfide, boron nitride and the like.

For the purpose of imparting an antistatic property to the back layer, a conductive agent such as carbon black and the like, and an antistatic agent such as a quaternary ammonium salt and a phosphoric ester can also be added.

To form the back layer, the material as described above is acetone,
A coating solution is prepared by dissolving or dispersing in a suitable solvent such as methyl ethyl ketone, toluene, xylene and the like, and the coating solution is applied by a conventional coating means such as a gravure coater, a roll coater, a wire bar and dried. Formed by

The coating amount, that is, the thickness of the back layer is also important, and in the present invention, the solid content is 0.5 g / m ² or less, preferably 0.1 to 0.
A back layer having sufficient performance can be formed with a thickness of 5 g / m ² . If the back layer is too thick, the sensitivity at the time of transfer decreases, which is not preferable.

It is also effective to form a primer layer from a polyester resin, a polyurethane resin, or the like on the base film before forming the back layer.

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

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

As the coloring agent, among organic or inorganic pigments or dyes, those having good characteristics as a recording material, for example, those having a sufficient coloring density and not discoloring by light, heat, temperature or the like are preferable.

In addition, a substance which is colorless when not heated but develops a color when heated, or a substance which develops a color when it comes into contact with a substance applied to a transfer target body may be used. In addition to the colorants that form cyan, magenta, yellow, and blocks, other various colorants can also be used.

As the vehicle, a mixture of wax as a main component, and other components such as a wax and a derivative of a drying oil, a resin, a mineral oil, cellulose, and rubber is used.

Representative examples of the wax include micro chloristerin wax, carnauba wax, and paraffin wax. Furthermore, various waxes such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti, Ibota wax, wool wax, shellac wax, candelilla wax, petrolatum, partially modified wax, fatty acid ester, fatty acid amide and the like are used. Can be

Further, a heat conductive substance can be added to the heat fusible ink in order to give the heat fusible ink layer good heat conductivity and melt transferability. Examples of this substance include carbonaceous substances such as carbon black, aluminum, copper, tin oxide, and molybdenum disulfide.

As a method for forming a hot-melt ink layer directly or indirectly on a base film, a hot-melt coat, a hot lacquer coat, a gravure coat, a gravure reverse coat, a roll coat, and the like are applied by various methods. And the like. The thickness of the ink layer to be formed should be determined so as to balance the required density with the thermal sensitivity, and is in the range of 0.1 to 30 μm, preferably 1 to 20 μm.

In the present invention, a surface layer can be further formed on the ink layer. The surface layer forms part of a transfer film,
It has a function of forming a surface in contact with the paper to be transferred, stopping a printed portion of the paper at the time of transfer, preventing background stains, and improving the adhesiveness of the ink layer to the paper to be transferred.

The wax used for forming the surface layer is the same substance as the wax used for the above-mentioned hot-melt ink layer.

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

Coating of the surface layer can also be performed by various techniques as in the formation of the ink layer. In the present invention, the thickness of this layer is preferably 0.1 μm so that the sensitivity may not be insufficient even when the printing energy is low as in a high-speed type printer.
m or more and less than 5 μm.

It is recommended that an appropriate amount of extender be added to the surface layer. Thereby, bleeding and tailing of the print can be prevented more favorably.

A thermal transfer image generally has a glossy print and is beautiful, but on the other hand, matte printing may be desirable because the document may be difficult to read. 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 or the like dispersed in an appropriate solvent is dispersed on a base film. It is preferable to form a thermal transfer sheet by coating and providing a mat layer, and then coating a hot-melt ink layer. Alternatively, the base film itself may be used after mat processing (the technique of Japanese Patent Application No. 58-208307 also proposed by the applicant).

Needless to say, the present invention can be applied to a thermal transfer sheet for color printing, and a multicolor thermal transfer sheet is also included in the scope of the present invention.

(Effects) According to the present invention as described above, the zinc salt or aluminum salt of the alkyl phosphate ester used in the present invention has a very excellent slip property, but is not less than 150 ° C., in many cases, With a melting point of 200 ° C or higher, it has excellent heat resistance, does not contaminate other articles and thermal heads, and has excellent slip properties without abrasion of the thermal head. A sheet is provided.

Examples Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the description, parts and% are based on weight unless otherwise specified.

Examples 1 to 5 Ink composition for back layer (1) Polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 6.0 parts zinc stearyl phosphate (LBT 1830, manufactured by Sakai Chemical Co., Ltd.) 6.0 parts urea resin Powder (organic filler, manufactured by Nippon Kasei Co., Ltd.) 1.8 parts Solvent (MEK / toluene = 1/1) 86.2 parts Ink composition for back layer (2) Polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 4.0 parts Polyvinyl butyral resin (ESLEK BLS, manufactured by Sekisui Chemical Co., Ltd.) 2.0 parts Aluminum stearyl phosphate (LBT 1813, manufactured by Sakai Chemical Co., Ltd.) 6.0 parts Melamine resin powder (Eposter S, manufactured by Nippon Shokubai Chemical Co., Ltd.) 1.8 parts Solvent (MEK / toluene = 1/1) 84.2 parts After stirring and mixing the above composition, dispersing with a paint shaker for 3 hours, and then treating 100 parts of the processed material with a polyisocyanate curing agent (Corone Capital L, manufactured by Nippon Polyurethane Co., Ltd.) 16
Parts and an appropriate amount of a diluting solvent (MEK / toluene = 1/1) were added to obtain ink for each back layer.

Each of the above inks was applied to a polyester film (thickness 6
μm, Lumirror F-53, manufactured by Toray Industries, Inc.) on a wire bar coater at a solid content of 0.2 g / m ² and 0.5 g / m ^{2 at} a rate of 48 hours in a 60 ° C. oven. Heat treatment was performed to form a back layer.

Back layer ink composition (3) Styrene / acrylonitrile copolymer (Sebian AD,
6.0 parts Cotton-like saturated polyester resin (Eritaire UE3200, manufactured by Unitika Ltd.) 0.3 parts Zinc stearyl phosphate (LBT 1813, manufactured by Sakai Chemical Co., Ltd.) 3.0 parts Crosslinked urea resin powder (organic filler, Nippon Kasei Co., Ltd.
3.0 parts Melamine resin crosslinked powder (Eposter S, Nippon Shokubai Chemical Co., Ltd.) 1.5 parts Solvent (MEK / toluene = 1/1) 86.2 parts Ink composition for back layer (4) Nitrified cotton H1 / 2 second resin (Celnova BTH1 / 2, Asahi Kasei Corporation
10.0 parts Cotton-like saturated polyester resin (Eritaire UE3200, manufactured by Unitika Ltd.) 2.0 parts Zinc stearyl phosphate (LBT 1813, manufactured by Sakai Chemical Co., Ltd.) 5.0 parts Urea resin crosslinked powder (organic filler, Nippon Kasei Co., Ltd.)
3.0 parts Solvent (MEK / toluene = 1/1) 80.0 parts Ink composition for back layer (5) Cellulose acetate propionate resin (CAP 482)
−05, Eastman Kodak Co., Ltd.) 10.0 parts Cotton-like saturated polyester resin (Polyester TP220, manufactured by Nippon Synthetic Chemical Co., Ltd.) 1.0 part Zinc stearyl phosphate (LBT 1813, Sakai Chemical Co., Ltd.) 3.0 parts Stearin Lithium acid (S-7000, manufactured by Sakai Chemical Co., Ltd.) 5.0 parts Solvent (MEK / toluene = 1/1) 80.0 parts / Toluene = 1/1) was added in an appropriate amount to prepare an ink for each back layer.

Each of the above inks was applied to a polyester film (thickness 6
μm, Lumirror F-53, manufactured by Toray Industries, Inc.) on a surface of a wire bar coater at a solid content of 0.2 g / m ² and 0.5 g / m ² , followed by hot-air drying to form a back layer. .

Separately, a transfer ink composition having the following composition was kneaded with a blade kneader for 6 hours while being heated to 1000 ° C.

Ink composition for forming transfer ink layer Paraffin wax 10 parts Carnauba wax 10 parts Ethylene / vinyl acetate copolymer (Smitate HC-10,
Sumitomo Chemical Co., Ltd.) 1 part carbon black (Seast 3, Tokai Electrode Co., Ltd.)
2 parts The above ink composition was heated at a temperature of 100 ° C., and coated on the other surface of each of the base films on which the back layer was formed by a roll coating method using a hot melt so that the coating amount was 5.0 g / m ² . To form a thermal transfer ink layer to obtain a thermal transfer ink of the present invention.

Using the thermal transfer sheet of the present invention obtained above, with a thermal printer, output 1W / dot, pulse width 0.3 to 4.5m
When printing was performed on plain paper under the conditions of sec. and a dot density of 3 dots / mm, the sticking phenomenon did not occur at all, no wrinkles occurred, and the thermal transfer sheet ran smoothly and had no problems.

Comparative Example 1 A thermal transfer sheet of Comparative Example was obtained in the same manner as in Example 1 except that zinc stearyl phosphate was not used.

A printing test was performed in the same manner as in Example 1. As a result, sticking was severe and printing was impossible.

Furthermore, the coefficients of friction, sticking resistance and stain resistance of the thermal transfer sheets of Examples and Comparative Examples were measured. The results shown in Table 1 below were obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-5884 (JP, A) JP-A-60-230896 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] 1. A thermal transfer sheet having a transfer ink layer which is melted by heating on one surface of a base film, and a back layer formed on the other surface of the base film contacting the thermal head. Is formed from a binder and a zinc salt or an aluminum salt of an alkyl phosphate. 2. A zinc salt or an aluminum salt of an alkyl phosphate, 2. The thermal transfer sheet according to claim 1, wherein R is an alkyl group having 12 or more carbon atoms, M is zinc or aluminum, and n represents a valence of M. 3. The thermal transfer sheet according to claim 1, wherein the zinc salt or aluminum salt of the alkyl phosphate is in a ratio of 10 to 200 parts by weight per 100 parts by weight of the binder.