JP2597356B2 - Thermal transfer ink film - Google Patents

Description

The present invention relates to a thermal transfer ink film which gives good print quality even to an image receiving paper having a low surface smoothness.

(B) Prior Art In recent years, thermal transfer recording for forming a transfer image on plain paper using a thermal printer, a thermal facsimile or the like has been actively developed.

This thermal transfer recording has recently attracted attention because of its simple apparatus, easy maintenance, low cost and low maintenance cost, and low energy, clear and robust recording.

The thermal transfer ink film used for the thermal transfer recording has a hot-melt ink layer coated on a support, and the hot-melt ink layer includes a colorant such as carbon black or a dye and a hot-melt ink such as wax. It is known to contain substances. As the support, a film such as polyethylene terephthalate having excellent surface smoothness, dimensional stability, heat resistance and the like is used.

However, in the conventional thermal transfer ink film, the printing quality is greatly affected by the surface smoothness of the image receiving paper, and good printing is performed on the image receiving paper having high smoothness. At present, there is a drawback that the print quality is reduced, and the improvement is being made from various aspects of the printing apparatus and the ink film.

(C) Problems to be Solved by the Invention As described above, when the image receiving paper having low smoothness is used, the ink melted at the time of printing cannot penetrate into the concave portion on the image receiving paper surface, and the convexity on the surface cannot be obtained. Since the ink adheres only to the portion or the vicinity thereof, the edge portion of the printed image is not sharp or a part of the image is missing, thereby deteriorating the printing quality. Further, in order to improve the printing quality, it is conceivable to use a heat-fusible polymer having a low melting point, but in this case, the heat-fusible ink layer is tacky even at a relatively low temperature, Inconveniences such as deterioration of storage stability and staining of the non-printed portion of the image receiving paper are caused. Also, the thickness of the hot-melt ink layer is increased from the usual 3-5 μm to 7-10 μm,
Increasing the applied energy is relatively effective, but causes problems such as the life of the thermal head and the printing speed, and is not practical.

As described above, an object of the present invention is to provide a thermal transfer ink film capable of giving good printing quality even to an image receiving paper having a low surface smoothness.

(D) Means for Solving the Problems The present inventor has conducted intensive studies to solve these drawbacks. As a result, the present inventors have developed a thermal transfer ink film that provides good printing quality even on an image receiving paper having a low surface smoothness. Could be provided.

That is, a thermal transfer ink film in which a heat-fusible ink layer is provided on a support and a thermal tack composition is applied on the heat-fusible ink layer, wherein the thermal tack composition is a polymer, a solid plasticizer and Tackifier as the main component,
These compounding ratios could be provided when the solid plasticizer was 20 to 1000 parts by weight and the tackifier was 5 to 800 parts by weight based on 100 parts by weight of the polymer.

 Hereinafter, the present invention will be described in more detail.

A typical example of the types and ratios of various chemical materials used in the thermal tack composition of the invention is described in, for example, "Adhesion Handbook", 12th edition (published in 1980) published by the Society of Polymer Publishing.
Basically, polyvinyl acetate, butyl pomethacrylate, vinyl chloride-vinylidene chloride copolymer, synthetic rubber, vinyl acetate-2-ethylhexyl copolymer allylate, vinyl acetate-ethylene copolymer, vinyl pyrrolidone-styrene Copolymers such as copolymers, styrene-butadiene copolymers, vinylpyrrolidone-ethyl acrylate copolymers and dicyclohexyl phthalate, diphenyl phthalate, dihexyl phthalate, dihydroabiethyl phthalate, dimethyl isophthalate, sucrose benzoate, Ethylene glycol benzoate, trimethylolethane tribenzoate, glyceride tribenzoate, pentaerythritol tetrabenzoate, sucrose octaacetate, tricyclohexyl citrate, N-cyclohexyl-p-toluene It comprises a solid plasticizer such as sulfonamide, dehydroabiethylamine carbonate, methoxyethyl stearate-urea complex, and preferably further comprises indene resin, ethyl cellulose, petroleum resin (hydrocarbon resin), terpene resin, rosin derivative (polymerized rosin) , Hydrogenated rosin, pentaerythritol ester of rosin, resin acid dimer, etc.).

In the above chemical materials, the polymer forms the root of adhesion, and the solid plasticizer does not impart plasticity to the polymer at room temperature.
Therefore, although the composition is non-tacky at room temperature, it is first melted and turned into a liquid state by heating to dissolve the polymer to develop tackiness. The tackifier is a component for increasing tackiness when activated by heating. Once they are once melted, they crystallize slowly, so that the duration of adhesion after heat activation can be lengthened, increasing practical utility.

The melting points of these thermal tack compositions, i.e., polymers, solid plasticizers and tackifiers, are each 40 to 120 ° C, preferably 50 to 90 ° C. If a problem occurs, and the melting point is higher than 90 ° C., a problem of transfer efficiency occurs.

The compounding ratio of the thermal tack composition of the present invention is polymer 10
20 to 1000 parts by weight of a solid plasticizer, preferably 50 to 500 parts by weight, and 5 to 800 parts by weight of a tackifier, preferably 10 to 300 parts by weight with respect to 0 parts by weight, are mixed in an aqueous dispersion, and then heat-melted. It can be obtained by aqueous coating on the hydrophilic ink layer. Alternatively, solvent coating or hot melt coating may be used depending on the material used. Further, it may be contained in the heat-meltable ink layer by using a suitable method. In the formulation of the thermal tack composition, if the solid plasticizer is less than 20 parts by weight, the development of tackiness due to heating hardly occurs,
If the amount is more than 00 parts by weight, the adhesive strength after heating is reduced, and the adhesive duration after heat activation is reduced. Also, if the tackifier is 5
If the amount is less than 10 parts by weight, the tack / adhesive strength after heating is low.

In the present invention, when coating the thermal tack composition on the heat-fusible ink layer, the film thickness of the heat-fusible ink layer is 20 μm or less, more preferably 1 to 10 μm, and the thermal tack layer is 10 μm or less, more preferably. Is 1 to 5 μm.

As the thermal tack composition used in the present invention, that is, the polymer, the solid plasticizer and the tackifier, conventionally known ones can be used, and further, if necessary, the viscosity at the time of melting is reduced, and the tackiness at room temperature is reduced. A heat-meltable substance such as wax can be blended for the purpose of controlling.

Such heat-fusible substances include the following. That is, as a wax-like substance, rice wax, wood wax, candelilla wax, vegetable wax such as carnauba wax, lanolin, beeswax, animal wax such as shellac wax, mineral wax such as montan wax,
Paraffin wax, microcrystalline wax,
Oxidized paraffin wax, chlorinated paraffin wax,
Synthetic waxes such as ricinoleic acid amide, lauric acid amide, erucic acid amide, palmitic acid amide, oleic acid amide, 12-hydroxystearic acid, distearyl ketone, ethylenebisstearic acid amide, etc., sodium stearate, sodium palmitate, laurin Metal soaps such as potassium phosphate, potassium myristate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, lead stearate, and dibasic barium stearate;
Higher fatty acids such as palmitic acid and stearic acid, higher alcohols such as palmityl alcohol, stearyl alcohol and ceryl alcohol, polyethylene glycol,
It is a synthetic polyalcohol such as polypropylene glycol, and may be used alone or as a mixture of two or more. Also, the melting point of the exemplified heat-fusible substance is 40 to 120 ° C.
In particular, a particularly preferable substance is a wax-like substance having a melting point of 50 ° C to 90 ° C. In addition, the transfer efficiency in the present invention is deteriorated because it is hard to be melted by a thermal head. The reason why the present invention gives good print quality even to an image receiving paper having a low surface smoothness has not been elucidated in detail, but is considered as follows.

That is, if the characteristics of the thermal tack composition described above are applied to a thermal transfer ink film, the ink layer transferred by the heating of the thermal head becomes flexible and adheres to both ends of the concave portion, as if a bridge were formed. Transcribed. If the transferred ink layer is not flexible but rather fragile, it is believed that the objects of the present invention cannot be achieved.

As the heat-fusible ink layer of the present invention, a conventionally known ink layer is used as it is, and is not particularly limited.

The colorant to be contained in the hot-melt ink layer of the present invention may be appropriately selected from dyes and pigments. Examples of the dye include basic dyes, oil-soluble dyes, acid dyes, direct dyes, and disperse dyes. You can choose from. On the other hand, as the pigment, inorganic pigments such as carbon black and iron black can be used in addition to organic pigments such as phthalocyanine pigments.

The heat-fusible substance used in the heat-fusible ink layer of the present invention may be the same as or different from the heat-fusible substance used in the thermal tack layer.

As the polymer, for example, butyral resin, ethylene ethyl acrylate, styrene-butadiene copolymer, vinyl acetate resin, vinyl acetate copolymer, acrylic resin,
Methyl methacrylic resin, styrene / acrylonitrile resin, ethylene-vinyl acetate copolymer, polyester resin, petroleum resin and the like can be mentioned.

In the hot-melt ink layer and the thermal tack composition of the present invention, in addition to the main components, additives such as a surfactant, a dispersant, an antiblocking agent, an animal and vegetable oil, and a mineral oil may be appropriately used. good. However, in the present invention, as long as the amount of addition other than the above main component does not exceed 40% of the total weight part, it can be used together with the above main component.

As the support, thin paper such as condenser paper, typewriter paper and tracing paper, synthetic paper, cellophane paper, and also synthetic resins such as polyester film, polyimide film, polyethylene ethylene film, polycarbonate film, polystyrene film, and Teflon film The film is used as it is or after being subjected to heat treatment so as not to adhere to the thermal head. Heat-resistant processing, silicone resin, on the surface where the thermal head on the opposite side to the transfer layer applied to these papers or films,
It can be performed by providing an epoxy resin, a melamine resin, a phenol resin, a fluorine resin, a polyimide resin, nitrocellulose, or the like.

Coating machines are air knife coater, roll coater,
Coating is performed by a known coater such as a blade coater or a bar coater, and a known printing machine such as a flexo method or a gravure method may be used.

(E) Function The thermal transfer ink film of the present invention can be printed on an image receiving paper such as plain paper by a known thermal transfer recording system.
In addition, good printing can be performed even on an image receiving paper having low smoothness. That is, in a thermal transfer ink film having a heat-fusible ink layer on a support, by applying a thermal tack composition onto the heat-fusible ink layer, the thermal transfer ink film is transferred like a bridge in a concave portion of an image receiving paper. Thus, it is considered that the heat-fusible ink layer gives good image quality on the image-receiving paper with less characters and white spots in black solid printing.

(F) Examples and Comparative Examples Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but embodiments of the present invention are not limited thereto. In addition, the part used below shows a weight part.

Example 1 A hot-melt ink having the following composition was coated on a polyethylene terephthalate (PET) film having a thickness of 6 μm to a thickness of 3 μm.
Thus, a thermal transfer ink film was prepared using a hot melt coater.

Carbon black 100 parts 150 ° F paraffin wax 550 parts No. 1 carnauba wax 250 parts Ethylene-vinyl acetate copolymer 100 parts Next, an emulsion of the following thermal tack composition was water-coated on the above-mentioned thermal transfer ink film using an air knife coater. Work, A thermal transfer ink film (the present invention) having a thermal tack layer having a thickness of 3 μm on the heat-meltable ink layer was prepared.

The evaluation method was a thermal transfer facsimile manufactured by Oki Electric Industry Co., Ltd.
Using the No.2 chart of the Institute of Image Electronics Engineers on a thermal transfer ink film created using OF-101 and receiving paper with a Beck smoothness of 3, 30, 100, and 300 seconds, transfer of the resolution of characters and fine lines and solid black printing Sex was visually evaluated. The results are shown in Table-1 and Table-
It is shown in FIG.

Comparative Example 1 In Example 1, the heat-meltable ink and the solid material of the thermal tack composition were mixed and melted, and a thermal transfer ink film having a film thickness of 3 μm was formed using hot melt coating. The results are shown in Table 1. However, at the time of printing, since the thermal tack composition was mixed and melted in the hot-melt ink, it was difficult for the ink to separate from the film, and a blocking state occurred in the feeding of the thermal transfer ink film.

Comparative Example 2 In Example 1, the heat-fusible ink and the solid product of the thermal tack composition were mixed and melted, and a 6 μm-thick thermal transfer ink film was formed by hot melt coating. The results are shown in Table 1. However, at the time of printing, since the thermal tack composition was mixed and melted in the hot-melt ink, it was difficult for the ink to separate from the film, and a blocking state occurred in the feeding of the thermal transfer ink film.

Comparative Example 3 The thermal tack composition was not applied in Example 1,
A thermal transfer ink film having only a 3 μm-thick hot-melt ink layer was prepared. The results are shown in Table 1.

Comparative Example 4 In Example 1, a thermal transfer ink film having only a 6 μm-thick hot-melt ink layer was prepared without applying the thermal tack composition. The results are shown in Table 1.

Next, specific examples and comparative examples are shown for the compounding ratio.

Examples 2 to 5 and Comparative Examples 5 to 8 Examples 2 to 5 and Comparative Examples 5 to 8
A thermal transfer ink film was prepared in the same manner except that the composition of the thermal tack composition was changed as shown in Table 2, and the resolution of characters and fine lines, the thermal transferability of solid black printing, and the presence or absence of blocking were visually evaluated. Table 2 shows the results.

As is clear from Tables 1 and 2, in a thermal transfer ink film having a heat-fusible ink layer on a support, a thermal tack composition was applied on the heat-fusible ink layer, and the thermal tack composition was Polymer, a solid plasticizer and a tackifier as a main component, the mixing ratio of these polymers 100
By setting the solid plasticizer to 20 to 1000 parts by weight and the tackifier to 5 to 800 parts by weight with respect to parts by weight, it was possible to give good printing quality even to an image receiving paper having low surface smoothness. .

(G) Effects of the Invention The thermal transfer ink film of the present invention can provide good print quality even on an image receiving paper having low surface smoothness by coating or including a thermal tack composition on a conventional thermal transfer ink film. This has made industrial significance extremely high.

Claims (1)

(57) [Claims] 1. A thermal transfer ink film comprising a support having a heat-fusible ink layer provided thereon, and a thermal tack composition coated on the heat-fusible ink layer, wherein the thermal tack composition comprises a polymer or a solid. Mainly plasticizer and tackifier,
A thermal transfer ink film characterized in that the mixing ratio of the solid plasticizer is 20 to 1000 parts by weight and the tackifier is 5 to 800 parts by weight based on 100 parts by weight of the polymer.