JPH0532075A - Thermal transfer sheet for multi-printing and method for printing many times - Google Patents

Abstract

PURPOSE:To provide the above thermal transfer sheet capable of multi-printing. CONSTITUTION:The present thermal transfer sheet for multi-printing and a method for multi-printing which uses said thermal transfer sheet are provided as follows: an ink layer consisting of a binder having polycaprolactone and wax as main components and a colorant is provided on one side surface of a base film: a transfer control layer which does not contain the colorant consisting of thermoplastic resin having polycaprolactone as a main component is provided further onto its surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet and a multiple printing method, and more particularly to a thermal transfer sheet and a multiple printing method capable of printing multiple times in the same area.

[0002]

2. Description of the Related Art Conventionally, when printing an output print of a computer or a word processor by a thermal transfer system, a thermal transfer sheet having a heat-fusible ink layer on one surface of a base film is used. The above-mentioned conventional thermal transfer sheet is used as a base material film such as condenser paper or paraffin paper having a thickness of 10 to 20 μm or a thickness of 3 to 20.
It is manufactured by using a film of plastic such as polyester or cellophane having a thickness of μm, and coating a hot-melt ink layer in which a colorant such as a pigment or a dye is mixed with wax.

[0003]

The greatest drawback of the above-mentioned thermal transfer sheet is that it can print only once in the same area of the thermal transfer sheet, which is very uneconomical. That is, in the case of a type ink ribbon in which a cloth tape which has been conventionally used is impregnated with ink, it is possible to perform printing more than once in the same area, whereas in the case of a thermal transfer sheet, it is possible to print once. Since the ink layer in the printed portion is entirely transferred by printing, printing cannot be performed twice or more at the same location, and the base material sheet used as the thermal transfer sheet becomes disposable once. In addition, the amount of ink actually transferred to the material to be transferred is a few% of the total amount of the thermal transfer sheet, and at most a dozen%.
Most other inks are discarded without being used. Therefore, an object of the present invention is to solve the above-mentioned drawbacks and to provide a thermal transfer sheet capable of printing many times.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention provides an ink layer composed of a binder mainly composed of polycaprolactone and wax and a colorant on one surface of a base film, and further comprises a thermoplastic resin mainly composed of polycaprolactone on the surface thereof. A thermal transfer sheet for multi-use printing, comprising a transfer control layer containing no colorant, and a multi-use printing method using the thermal transfer sheet.

[0005]

By using polycaprolactone and wax as the binder of the ink layer and the transfer control layer mainly of polycaprolactone, it is possible to print many times. When the control layer is not present, most of the ink layer is transferred by one printing, and printing more than that number does not result in practical density printing.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the preferred embodiments. As the base film used in the present invention, the same base film as that used in the conventional thermal transfer sheet can be used as it is, and other films can also be used and are not particularly limited. Specific examples of the preferred base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer and the like. , Such as plastic film, condenser paper, paraffin paper, non-woven fabric, etc.
Further, it may be a base film which is a composite of these. The thickness of the base film can be appropriately changed according to the material so that its strength and thermal conductivity are appropriate.
The thickness is preferably, for example, 2 to 25 μm.

In the present invention, when the adhesiveness between the base film and the ink layer formed on the surface is insufficient, it is preferable to form an adhesive layer (ink holding layer). The above-mentioned adhesive layer is not necessary when it adheres well to the ink layer. To form the adhesive layer, for example, polyvinyl acetate, ethylene-vinyl acetate copolymer, vinyl chloride-ethyl acetate copolymer, ethylene-acrylic acid ester copolymer, polybutene, petroleum resin, vinyl chloride resin, methacrylic resin Thermoplastic resins such as polyamide, polyester, and high molecular weight polycaprolactone are used. The thickness of the adhesive layer may be slight, for example, about 0.05 to 5 μm. By providing this adhesive layer, the adhesiveness between the base film and the ink layer is improved, and it is possible to effectively prevent the entire ink layer from being transferred by the first printing.

The ink layer formed directly on the base film or on the adhesive layer may contain a colorant and a binder as main components, and may further contain various additives as required. The colorant is preferably an organic or inorganic pigment or dye having good characteristics as a recording material, for example, a pigment having a sufficient coloring density and not fading due to light, heat, temperature or the like. Cyan, magenta,
In addition to the colorants forming yellow and black, colorants of various other colors can also be used. The binder is mainly composed of polycaprolactone and wax, and other resins for the adhesive layer can be mixed and used, but the other resin used in combination is equal to or less than the total amount of polycaprolactone and wax. If there are many other resins used together, it becomes difficult to print many times. The preferable combination ratio of the adhesive resin is 0.
It is about 3 to 5% by weight. Ink layer thickness is 5 ~ 15μ
About m is preferable.

In the present invention, a transfer control layer is provided on the surface of the ink layer. This transfer control layer is preferably formed from the same polycaprolactone used for the ink layer. In the most preferred embodiment, both the ink layer and this transfer control layer are formed from polycaprolactone having a molecular weight of about 6,000 to 20,000. The thickness of the transfer control layer is preferably about 0.3 to 2.0 μm. As a method for forming each of the above layers, conventionally known hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating and many other known methods can be used, and also a method using an aqueous or non-aqueous emulsion can be adopted. Is. The total layer thickness is 10 to 20 μm, preferably 10 to 12 μm.

When a material weak to heat is used for the base film, it is preferable to provide a layer for preventing sticking of the thermal head on the surface in contact with the thermal head. The sticking prevention layer contains a heat-resistant resin and a substance acting as a thermal release agent or a lubricant as basic constituent components. A resin having heat resistance has a glass transition point of 60.
Those obtained by adding a compound having two or more amino groups or a diisocyanate or triisocyanate to a synthetic resin having a temperature of not lower than ° C or a thermoplastic resin having an OH group or a COOH group to cause a slight crosslinking and curing are preferable. Thermal release agents or lubricants, such as amides, esters and salts of waxes and higher fatty acids, which act by melting by heating,
Some are useful as solids, such as powders of fluororesins and inorganic substances. By providing such a sticking prevention layer, thermal printing can be performed without sticking even on a thermal transfer sheet using a plastic film that is weak against heat as a base. You can take advantage of such advantages. Needless to say, the present invention can be applied to a thermal transfer sheet for color printing, so that a multicolor thermal transfer sheet is also included in the scope of the present invention. Further, the thermal transfer printer can be applied to either a line type or a serial type. The multiple-printing method of the present invention is a method of using the above-mentioned thermal transfer sheet and performing multiple printing multiple times using the same thermal transfer sheet with an ordinary thermal transfer printer, and the printer and the printing method itself used are conventional techniques. The same as

[0011]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on weight. Example 1 Emulsified components were sufficiently stirred according to the following formulation to prepare an emulsion ink. Emulsion ink : Polycaprolactone H1 (manufactured by Daicel Chemical Industries) (solid content 20%) 40 parts Paraffin wax HNP-11 (manufactured by Nippon Seiro Co., Ltd.) (solid content 20%) 40 parts Ethylene / vinyl acetate copolymer Everflex # 210 ( Mitsui Polychemical) (Solid content 20%) 10 parts Carbon black (Solid content 20%) 10 parts The above ink composition was applied to a surface of a polyethylene terephthalate film having a thickness of 6 μm by a roll coating method in a dry thickness of 1
An ink layer was formed by coating and drying so that the thickness was 2 μm. Next, polycaprolactone H1 is applied to the surface of the ink layer.
A methyl ethyl ketone solution (manufactured by Daicel Chemical Industries, Ltd.) is coated and dried by a roll coating method so that the dry coating amount becomes 0.5 g / m ^2, and a transfer control layer is formed. Got

Example 2 A polycaprolactone ink composition having the following composition was prepared by mixing for 5 hours while heating to 50 ° C. using a sand mill. Polycaprolactone ink : Polycaprolactone H1 (manufactured by Daicel Chemical) 80 parts Polycaprolactone H4 (manufactured by Daicel Chemical) 10 parts Paraffin wax (methyl ethyl ketone dispersion, solid content 20%) 45 parts Carbon black (methyl ethyl ketone dispersion, solid content 40%) 14 parts Methyl ethyl ketone 350 parts 10 g / dry weight of the above composition on the surface of a polyethylene terephthalate film having a thickness of 6 μm by a roll coating method
An ink layer was formed by coating so that the ink layer had a thickness of m ² . Next, a methyl ethyl ketone solution of polycaprolactone H1 (manufactured by Daicel Chemical Industries, Ltd.) was applied to the surface of the ink layer by a roll coating method so that the dry coating amount was 0.5 g / m ² and dried to form a transfer control layer. A thermal transfer sheet for multi-time printing of the present invention was obtained.

Example 3 A high molecular weight polycaprolactone adhesive layer (thickness 0.5 μm) between the substrate film and the ink layer in Example 1
A thermal transfer sheet for multi-time printing of the present invention was obtained in the same manner as in Example 1 except that the above was provided. Comparative Example 1 A thermal transfer sheet of Comparative Example was obtained in the same manner as in Example 1 except that the formation of the transfer control layer was omitted.

Example of Use Using the thermal transfer sheets of the above-mentioned Examples and Comparative Examples, printing was carried out a number of times at the same location under the following printing conditions, and the image density was measured to obtain the results shown in Table 1. Printing conditions Equipment used: Toshiba simulator equipped with a thin-film thermal head Printing energy: 0.4 mJ / dott (constant) Transfer material: Fine paper (made by Sanyo Kokusaku Pulp, KYP 46 edition 1)
25KG)

[Table 1]

[0015]

As described above, according to the present invention, there is provided a thermal transfer sheet for multi-use printing, which enables good printing with high density and small density difference.

Claims (4)

[Claims] 1. An ink layer comprising a binder mainly composed of polycaprolactone and wax and a colorant is provided on one surface of a substrate film, and further, a coloring comprising a thermoplastic resin mainly composed of polycaprolactone is provided on the surface thereof. A thermal transfer sheet for multi-use printing, comprising a transfer control layer containing no agent. 2. The thermal transfer sheet for multi-time printing according to claim 1, wherein an adhesive layer is provided between the base film and the ink layer. 3. The molecular weight of polycaprolactone is 6,000.
The thermal transfer sheet for multiple printing according to claim 1, wherein the thermal transfer sheet has a range of 0 to 20,000. 4. A thermal transfer method in which thermal energy is applied from the backside of a thermal transfer sheet with a thermal head to print on a transfer material, the thermal transfer sheet according to claim 1 is used as the thermal transfer sheet, and the same thermal transfer sheet is used. A method of printing multiple times characterized by printing repeatedly.