JP2598895B2 - Thermal transfer sheet - Google Patents

Description

The present invention relates to an improvement in a thermal transfer sheet, and more particularly, to a thermal transfer sheet having a matte printing function, an antistatic function, or a function of preventing leakage of confidential information.

[Conventional technology]

When a computer or word processor prints by a thermal transfer method, a thermal transfer sheet having a heat-meltable ink layer provided on one surface of a base film is used. Conventional heat-sensitive transfer sheets have a thickness of 10 to 20
Using a paper such as μ condenser paper or paraffin paper, or a plastic film such as polyester or cellophane with a thickness of 3 to 20μ, mixing the pigment with the wax and producing a hot-melt ink layer by coating. It was done.

However, prints or images recorded by a thermal printer are generally glossy. Although glossy printing is beautiful, it is not preferable from the standpoint of legibility. Therefore, it is desired to perform matte printing.

If paper is used instead of plastic as the base film, the glossiness of printing will be low, but it is still insufficient, and plastic, especially polyester, can be made into a thin film (1.
(Up to about 6μ) and high strength. Therefore, the demand for matte printing is strong.

Further, when the base film is made of plastic, static electricity is severely generated, and there are many problems in handling and printing quality such as clinging to hands or adsorbing dust, so that it is necessary to perform antistatic treatment.

In addition, reading can be performed by removing ions in a portion printed and heated by the thermal head,
There is a risk of leaking confidential information.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive transfer sheet which can improve the above-mentioned drawbacks of the conventional heat-sensitive transfer sheet, and can provide matte printing, antistatic or leak-proof functions.

Configuration of the Invention [Means for Solving the Problems] In the present invention, a heat-sensitive transfer comprising a mat layer containing carbon black as a resin and a matting agent on a base film and a heat-meltable ink layer on the base film A heat transfer sheet is characterized in that the heat solvent melting point ink layer contains a conductive powder.

[Specific description of the invention]

Base films include conventional polyester, polypropylene, cellophane, acetate, polycarbonate and other plastic films, and condenser paper,
Use paper such as paraffin paper. Polyester film is most suitable.

The hot-melt ink layer that characterizes the present invention must have the following properties. [If necessary for (2)] (1) Antistatic property: When the base film is plastic, it is particularly necessary to prevent generation of static electricity. If the surface resistance is 10 ⁹ Ω or less, problems such as clinging and sticking of dust in handling the ribbon will not occur in experience.

(2) The same color as the color of the mat layer is effective when it is necessary to prevent leakage of confidential information.

In order to obtain the above properties, the heat-meltable ink layer is composed of the following materials.

A) Conductive powder nickel, iron, copper, silver, aluminum, gold, cadmium, cobalt, chromium, magnesium, molybdenum,
Metal powders such as lead, palladium, platinum, rhodium, tin, tantalum, titanium, tungsten, zinc, zirconium or oxides or carbon blacks of these metal powders,
Conductive carbon such as graphite is used.

A) Colorant In addition to the colorants that form cyan, magenta, yellow, and black, colorants of various other colors can also be used.

That is, the hot-melt ink layer is selected and added as a colorant in accordance with the color to be provided to the hot-melt ink layer with carbon black or various dyes and pigments.

C) EVA, paraffin wax, carnauba wax, etc.

The coating amount of the hot-melt ink is suitably 3 to 5 μm in order to stably perform high-quality printing.

Further, the mat layer which is another feature of the present invention must have the following characteristics.

[If necessary for (4)] (1) Heat resistance: When the matte layer is softened or melted by the heat of the thermal head, heat energy is lost first, causing a decrease in sensitivity. Secondly, the matte layer adheres to the ink surface due to peeling between the base film and the matte layer, reducing the matte effect, and thirdly, the degree of adhesion between the matte layer and the hot-melt ink layer changes. However, when tackiness occurs in the mat layer, there is a problem that uneven transfer occurs due to the remaining ribbon of ink.

(2) Thermal exfoliation property ... It is necessary that the peeling property during heating between the mat layer and the hot-melt ink layer be good.

(3) Being a thin film: The preferred film thickness is 0.2 to 3 μm. In order to secure a preferable average mat depth of 0.15 to 2 μ, a thickness of 0.2 μ or more is required. If it exceeds 3 μm, the thermal sensitivity becomes low.

(4) The same color as the color of the hot-melt ink layer is an effective means when it is necessary to prevent leakage of confidential information.

In order to obtain the above properties, the mat layer is composed of the following resin and matting agent. In addition, a heat releasing agent or a lubricant and a coloring agent as described below can be used as needed.

A) Resin A synthetic resin having a glass transition point of 60 ° C. or higher is suitable. Representative examples are acrylic resins, polyester resins, phenolic resins, fluorine resins, polyimide resins, methyl methacrylate resins, vinylidene fluoride resins, vinylidene fluoride-tetrafluoroethylene copolymer resins, polyvinyl fluoride resins, acrylonitrile- And styrene copolymer resin.

A resin obtained by adding a compound having two or more amino groups or a diisocyanate or triisocyanate to a thermoplastic resin having an OH group or a COOH group is also suitable.

Thermoplastic resins having OH groups or COOH groups include polyester resins, vinyl chloride / vinyl acetate copolymers, polyether resins, polybutadiene resins, acrylic polyols,
Urethane or epoxy prepolymers with OH groups,
A nitrocellulose resin, a cellulose acetate propionate resin, a cellulose acetate butyrate resin, or a cellulose acetate resin is preferred. These resins are
In addition to those having an OH group or a COOH group in the polymerized unit, those having a terminal or side chain may be used.

Examples of the diisocyanate to be added to the above-mentioned thermoplastic resin having an OH group or a COOH group include paraphenylene diisocyanate, 1-chloro-2,4-phenyl diisocyanate, 2-chloro-1,4-phenyl diisocyanate, 2, Four
-Toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalenediisocyanate, hexamethylene diisocyanate and 4,4'-biphenylenediisocyanate, examples of triisocyanates are
Triphenyl methane triisocyanate and 4,4 ',
4'-trimethyl-3,3 ', 2'-triisocyanate-
2,4,6-triphenyl cyanurate. Examples of the compound having two or more amino groups include melamine, methylated melamine, methylated methylol melamine, butylated melamine, butylated methylol melamine, dicyandiamide, guanidine, biguanide, diaminomelamine, granylmelamine, urea, biuret, Ammeline, ammelide, butylated urea and methylated urea, and guanamines such as formoguanamine, acetoguanamine, benzoguanamine, phenylacetoguanamine, methoxyguanamine and N-methylolacrylamide copolymer polymers can also be used.

When a compound having two or more amino groups is used, as a curing catalyst, ammonium phosphate, triethanolamine, acetamide, urea, pyridine, paratoluenesulfonic acid, sulfanilic acid, guanidine stearate, guanidine carbon, and the like are used. I do. Diisocyanate, triasocyanate and amino compound are used alone or as a mixture of two or more, and are 5 to 40 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of a thermoplastic resin having an OH group or a COOH group. Added. As these crosslinking agents,
The mat layer is appropriately cured and the adhesive strength of the plastic film of the mat layer is increased.

B) Thermal Release Agent or Lubricant There are two types of substances that enhance the releasability between the mat layer and the hot-melt ink layer when heated, such as those that melt when heated to exhibit this performance and those that work as solid powders. .

Those belonging to the former group include waxes such as polyethylene wax and paraffin wax, amides, esters and salts of higher fatty acids, and phosphate esters such as higher alcohols and lecithin. The latter group includes fluoroplastics such as Teflon and polyvinyl fluoride, guanamine resins, boron nitride, silica, wood flour, talc and the like. Of course, two groups may be used together. The usage amount is 10-50 in the mat layer
% By weight of the thermal release agent or lubricant.

C) Matsut agent Use an appropriate amount of carbon black.

D) Colorant In addition to the colorants that form cyan, magenta, yellow, and black, other various colorants can also be used.

That is, the mat layer is selected and added as a colorant in accordance with the color which gives carbon black or various dyes and pigments to the mat layer.

The thermal transfer sheet of the present invention may include various modifications. One example is to provide a primer layer on the base film to increase the adhesion between the base film and the mat layer.
The primer layer can be easily formed by applying a known primer coating. For example, it is preferable to use a combination of an acrylic resin, a polyester resin, a polyvinyl acetate resin, a vinyl chloride / vinyl acetate resin, a polyol and a diisocyanate, a polyol and a melamine, or a combination of an epoxy resin and a diisocyanate as a binder. The primer dye has a remarkable improvement in adhesive strength, particularly when the base film is polyester.

Another example is to provide a layer for preventing staking between the base film and the thermal head, which may occur depending on printing conditions. The anti-stating layer has, as basic components, a heat-resistant resin and a substance that functions as a heat release agent or a lubricant. As a heat-resistant resin, a synthetic resin having a glass transition point of 60 ° C. or higher, or a compound having two or more amino groups or a diisocyanate or triisocyanate added to a thermoplastic resin having an OH group or a COOH group to cause a slight crosslinking. Those that have been cured are preferred. Thermal release agents or lubricants can be heated and melted by heating such as waxes or amides, esters and salts of higher fatty acids, or solid such as fluorine resin or inorganic powder. Some are useful.

[Action]

By forming a heat-meltable ink layer containing conductive powder on a mat layer containing carbon black as conductive powder, higher antistatic performance can be imparted. Further, the matte layer can print matted characters and graphics which are easy to see. Further, by adding an appropriate colorant to the mat layer in advance so as to have the same color as the hot-melt ink layer, the concealing property is improved, and a function of preventing leakage of confidential information can be provided.

〔Example〕

(Matsu layer ink I) ・ 6 parts by weight of polyester resin (Toyobo “Vylon 200”) ・ 7 parts by weight of vinyl chloride / vinyl acetate copolymer resin (“VINYLITE VAGH” manufactured by UCC) ・ 3 parts by weight of calcium carbonate ・ Carbon black 4 Weight (Cabot Corporation "Raben 155") ・ Methyl ethyl ketone 30 parts by weight ・ Toluene 30 parts by weight Based on the above composition, a 50% butyl acetate solution of isocyanate (Takeda Pharmaceutical “Takenate D-204”) is used. What was mixed at a ratio of 20: 3 (weight ratio, the same applies hereinafter) in the product: isocyanate is referred to as a mat layer ink I.

(Heat-meltable ink I)-10 parts by weight of paraffin wax-10 parts by weight of carnauba wax-1 part by weight of ethylene / vinyl acetate copolymer (Sumitomo Chemical "Smitate HC-10")-2 parts by weight of conductive carbon ( (Lion Akzo Co., Ltd .: Ketjen BLACK) Example 1 Using a 6 μm thick polyethylene terephthalate (Toray) as a base film, the mat layer ink I was applied by a gravure printing method at a coating amount of 1 g / m ² . On the mat layer ink I, the hot-melt ink I was heated at 100 ° C.
Roll coating method by hot melt method
μ to obtain a thermal transfer ink layer.

Comparative Example (Hot-melt ink III)-10 parts by weight of paraffin wax-10 parts by weight of carnauba wax-1 part by weight of ethylene / vinyl acetate copolymer (Sumitomo Chemical "Smitate HC-10")-2 parts by weight of carbon black (Tokai electrode "Seast SO") The above composition was heated at 100 ° C x 6 using a blade kneader.
What was kneaded for a time was used as a hot-melt ink III.

(Heat-meltable ink IV) The above-mentioned hot-melt ink I was prepared by changing the carbon black to 2 parts by weight of a yellow pigment (Dainichi Seika 2400).

The above composition was heated at 100 ° C. × 6 using a blade kneader.
What was kneaded for a time was used as a hot-melt ink IV.

Comparative Example 1 A 6 μm thick polyethylene terephthalate (Toray) was used as a base film, and the hot-melt ink III was heated to 100 ° C. without a matte layer by a hot melt method to a thickness of 5 μm by a roll coating method. It was applied to form a thermal transfer ink layer.

Comparative Example 2 Hot melt ink III of Comparative Example 1 was subjected to IV.

The heat-sensitive transfer sheets of Example 1 and Comparative Examples 1 and 2 were slit into ribbons and printed by a commercially available printer.

Medium to be transferred High-quality paper (Mitsubishi Paper "Tokuhyo Rishi" 46 / 72Kg Thermal head Thin-film thermal head Printing energy 1mJ / dot (4 × 10 ^-4 cm ² ) Next, gloss by the thermal transfer sheet of the present invention Erased printing,
The effects of antistatic and confidential leakage prevention are shown below. (Table.
1) In general, the matte required for printing depends on the glossiness of the recording paper and the reading conditions. However, if the glossiness measured with a gloss meter is approximately 30 or less, it is always sufficient. It can be said that there is. With the present invention, this can be easily achieved. In Table.1, if the glossiness was 30 or less, it was evaluated as ○, and if it was 30 or more, it was evaluated as ×. The antistatic effect is ○, 10 ⁹ Ω if the surface resistance after applying the hot-melt ink is 10 ⁹ Ω or less
If it was above, it was evaluated as ×. Regarding the effect of preventing leakage of confidential information, the ribbon after printing was observed and the portion from which the hot-melt ink was removed was readable, and x was impossible.

The gloss was measured at a measurement angle of 60 ° using a gloss meter (Murakami Color Research Laboratory “GM-3M”). Surface resistance is super insulation resistance meter YHP 4329A-16008A
Was measured.

〔The invention's effect〕

The heat-sensitive transfer sheet of the present invention has the above-described structure, and can be used to perform a heat-sensitive transfer having a matte printing, an antistatic function, or a security leakage preventing function.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsuro Irita 1-40 Kotake-cho, Nerima-ku, Tokyo (72) Inventor Kyoichi Yamamoto 7-29-5 Sagamidai, Sagamihara-shi (72) Inventor Kyohei Takahashi 4--Minamidai, Sagamihara-shi 11 Tsurugaoka housing complex 2-112 (56) References JP-A-60-219091 (JP, A) JP-A-59-198194 (JP, A) JP-A-60-107392 (JP, A) JP-A-60-1884881 (JP, A) Fully open sho 59-225991 (JP, U) Really open sho 59-64394 (JP, U) Fully open sho 60-212393 (JP, U)

Claims (5)

(57) [Claims] 1. A heat-sensitive transfer sheet comprising a base film provided with a mat layer containing a resin and carbon black as a matting agent and a heat-meltable ink layer, wherein the heat-meltable ink layer is electrically conductive. A heat-sensitive transfer sheet comprising a powder. 2. A heat-sensitive transfer sheet according to claim 1, wherein a mat layer is provided after a primer layer is applied to the base film, so that the adhesive strength between the base film and the mat layer is increased. 3. The heat-sensitive transfer sheet according to claim 1, wherein a layer for preventing sticking to a thermal head is provided on the other surface of the base film. 4. The conductive powder is nickel, iron, copper, silver, aluminum, gold, cadmium, cobalt, chromium, magnesium, molybdenum, lead, palladium, platinum, rhodium, tin, tantalum, titanium, tungsten, zinc, 2. The heat-sensitive transfer sheet according to claim 1, wherein the heat-sensitive transfer sheet is made of a metal powder such as zirconium or an oxide of these metal powders or a conductive carbon such as carbon black or graphite. 5. The heat-sensitive transfer sheet according to claim 1, wherein the heat-meltable ink layer and the mat layer have the same color.