JP2996623B2 - Thermal transfer sheet - Google Patents

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 for forming an image by transferring a transfer layer on a support to an object to be transferred by a hot stamping method using hot stamping. The present invention relates to a thermal transfer sheet which can be favorably transferred onto a transfer body of a plastic film composed of a polyolefin or the like to be used, and in which a transferred image is excellent in mechanical abrasion resistance and the like.

[0002]

2. Description of the Related Art Conventionally, a heat transfer sheet for transferring an image on a support by transferring a transfer layer on a support to an object to be transferred by a hot stamping method by hot stamping, that is, a so-called hot stamping ribbon, is used for a material such as a packaging material. It may be used for printing the date of the expiration date of the food on the transfer body, and the configuration of the ribbon for hot stamping may be the one provided with a release layer, a colored ink layer on the support, or the release In some cases, a layer, a colored ink layer, and an adhesive layer are sequentially provided. However, these hot stamp ribbons do not have sufficient printing durability after transfer, or the transfer between the transfer target and the ribbon during transfer.
In some cases, pulling occurs due to the imbalance in adhesive strength, and transfer failure due to sticking occurs. In addition, conventional hot stamping ribbons using a metal-deposited layer such as gold and silver were also thin.However, in order to reduce the above-mentioned drawbacks, in a colored ribbon, the total of each layer excluding the support was not sufficient. It is designed to have a thickness of about 6.0 to 12.0 μm, which causes problems such as powder falling off due to the impact during hot stamp printing by hot stamping.

[0003] Conventional ribbons for hot stamping are:
The printed matter after transfer was relatively weak against mechanical abrasion. Further, in the packaging industry and the like, with the adoption of functional packaging materials and an increase in demand, the use of transfer-receiving objects has been expanded from conventional ones to those having a wider variety of types. Depending on the transfer target, good transfer cannot be performed with the ribbon having the conventional configuration, or the printed material is transferred, but the printed matter is removed by relatively simple rubbing. Problems such as not satisfying the abrasion resistance also occurred.

As means for improving the durability of printed matter,
A transfer layer containing chlorinated polypropylene has been proposed in JP-A-54-62009, and a combination of polyamide and chlorinated polypropylene in the adhesive layer has been proposed in JP-A-4-296588. However, these are those in which characters and pictures are applied to the sheet in advance and the whole is transferred with a heat roller, etc., and although the durability of the printed matter is improved, the thickness of the transfer sheet, powder fall,
The sticking of fine characters, surface peeling, etc. are not considered, and the hot stamp printing of the printing method of the present invention, in which a hot stamp ribbon coated with transfer ink is transferred by hot stamping and printed on the entire surface of the sheet, It could not be used practically.

[0005]

According to the hot stamping method of transferring and printing a hot stamping ribbon in which transfer ink is applied to the entire surface of a sheet by thermal engraving, it is not necessary to provide characters or pictures on the sheet in advance. From that
Necessary information can be printed more easily and when needed, which is very convenient. In particular, it is most suitable for applications in which print information frequently changes, such as printing the date on a packaging material such as food.

As described above, the environment in which a printed material printed by the hot stamp method of transferring and printing a hot stamp ribbon in which a transfer ink is coated on the entire surface of the sheet by thermal engraving is used, as described above. It is increasingly used in harsher environments. For example, printing under severe room temperature, use in an environment in which printed matter is mechanically scratched, and boiling in boiling water for tens of minutes.

[0007] Accordingly, as described above, a durable material is used for the object to be transferred, and the transfer of the material to the object to be transferred to the object or a printed object that only needs to be printed are required. There have been problems in obtaining printed matter having durability.

In other words, the hot stamping method of transferring and printing a hot stamp ribbon in which transfer ink is coated on the entire surface of the sheet by thermal engraving allows good thermal transfer to a durable transfer object, and further prints. A major issue has arisen in obtaining a printed material that satisfies both requirements of obtaining printed matter with sufficient durability.To achieve that task, it is necessary to consider the components of each transfer layer of the thermal transfer sheet and their thickness. I thought there was a big solution key. Although research on the composition of the components of the transfer layer has been conventionally conducted, no proposal has been made yet to reach the level required for the present invention. The aim of the invention is to propose exactly this solution.

[0009]

According to the present invention, in order to solve the above-mentioned problems, at least a heat sensitivity control layer, an anti-sticking layer, a colored ink layer and the like are sequentially laminated on a support, and the composition is specified in the composition. The present invention has been completed by blending the following components. That is, the present invention provides: “1. a thermal transfer sheet in which at least a thermal sensitivity control layer, a sticking prevention layer containing a water-soluble styrene-acrylic copolymer, and a colored ink layer are sequentially laminated on a support. 2. The thermal transfer sheet according to item 1, wherein the total of each layer excepted is 2.5 to 6.0 μm 3. The item 1 or 2, wherein the weight-average molecular weight of the water-soluble styrene-acrylic copolymer is 1500 to 15,000. 4. The thermal transfer recording medium of 4. The thermal transfer sheet according to any one of Items 1 to 3, wherein an adhesive layer is provided outside the colored ink layer 5. The first outermost layer containing chlorinated polypropylene as viewed from the support side Item 5. The thermal transfer sheet according to any one of Items 1 to 5, wherein the thermal transfer sheet according to any one of Items 1 to 5 includes a polyamide in the outermost layer when viewed from the support side.

[0010] According to the above configuration, the image is transferred by hot stamping.
When printing is performed using the above-mentioned thermal transfer sheet by the hot stamping method for printing, good thermal transfer can be performed, and a printed matter having sufficient durability can be obtained.

The thermal transfer sheet of the present invention is obtained by sequentially laminating at least a thermal sensitivity control layer, an anti-sticking layer containing a water-soluble styrene-acrylic copolymer, and a colored ink layer on a support.

The thermal sensitivity control layer is used to transfer the adhesive force between a transfer layer such as a colored ink layer and a support and the peeling force at the time of transfer when the transfer layer is thermally transferred by applying heat, in order to perform good transfer. This is a layer that is controlled to be optimal. Its composition is mainly composed of wax. Examples of the wax used for the heat sensitivity control layer include paraffin wax, candelilla wax, microcrystalline wax, polyethylene wax, beeswax, carnauba wax, gay wax, mokurou, nuka wax, montan wax, ozokerite, ceresin, ester wax, and Fischer-Trops wax. And higher fatty acid waxes such as myristic acid, palmitic acid, stearic acid, furomenic acid, behenic acid, lauric acid and margaric acid; and amide waxes such as stearinamide and oleinamide.

The thermal sensitivity control layer may contain a thermoplastic resin as a binder for the coating surface in addition to the wax.
In the case of printing with high-temperature hot stamping that loses the adhesive strength of the wax during transfer, it is necessary to generate a suitable tension between the support and the transfer layer, so the binder effect on the coated surface Apart from this, a thermoplastic resin is an essential component in terms of thermal sensitivity control. Without thermoplastic resin,
At the time of transfer, the adhesive strength to the support is remarkably reduced, and the printed matter is poor in sharpness and the surface is unclear.
The blending amount of the thermoplastic resin in the heat sensitivity control layer is preferably 5 to 15% by weight.

The sticking prevention layer assists the thermal sensitivity control layer when printing is performed by the hot stamp method of printing by hot stamping, and optimizes the adhesive force between the transfer layer and the support and the peeling force during transfer. It is a layer to control. Due to the action of the layer, transfer is preferably performed by thermal engraving under printing conditions in which good transfer cannot be obtained only by successively stacking a thermal sensitivity control layer, a coloring ink layer, and an adhesive layer on the support in order. Prevents sticking of the transferred object and the ribbon due to the imbalance between the adhesive force between the fine transfer layer and the support and the peeling force to the transfer generated for printing, and is excellent in fine patterns, etc. This makes it possible to obtain good printing.

The sticking prevention layer is substantially a layer made of a water-soluble styrene-acrylic copolymer. The sticking prevention layer is preferably such that the adjacent thermal sensitivity control layer and the colored ink layer have an incompatible relationship. It is considered that the sticking prevention performance is not greatly affected by the Tg and softening point of the copolymer, and is affected by the unique film strength and incompatibility of the copolymer. The water-soluble styrene-acrylic copolymer exhibits particularly good sticking prevention performance in the thermal transfer sheet of the present invention. Further, the thermal sensitivity to transfer is good, and the anti-sticking layer made of the copolymer is a layer having a very important meaning.

The weight average molecular weight of the water-soluble styrene-acrylic copolymer is preferably from 1500 to 15,000. When the average molecular weight is less than 1500, the film strength becomes weak,
It tends to stick easily, and if it exceeds 15000,
Thermal sensitivity tends to deteriorate, which is not preferable.

The sticking prevention layer may contain a coloring agent up to about 80% by weight in order to supplement the coloring power of the coloring ink layer. However, if a large amount is blended, the printability deteriorates, the sharpness deteriorates, and problems such as blurred printing occur, which is not preferable. It is preferably used within a range that does not substantially affect the performance of the water-soluble styrene-acrylic copolymer. When the mechanical resistance of the transferred image is required, it is better to reduce the content to about 40% by weight or not to contain it at all.

Furthermore, the incorporation of another thermoplastic resin or wax into the anti-sticking layer should be avoided as much as possible, since it has an adverse effect on the anti-sticking performance of the water-soluble styrene-acrylic copolymer.

The coloring ink layer comprises at least a coloring agent and a thermoplastic resin. Coloring agents include carbon black, permanent red, watching red, monolight fast red, alizarin lake, quinacridone, lake red, benzimidazolone red, phthalocyanine blue, cerulean blue, cobalt blue, victoria blue lake, ultramarine and navy blue. , Indanthrene blue, benzidine yellow, chrome yellow, cadmium yellow, Hansa yellow, molybdenum orange, disazo yellow, phthalocyanine green, zinc green, dioxazine violet, cobalt violet, mineral violet, benzidine orange, pyrazolone orange, permanent orange, indance Organic and inorganic pigments such as rembrilliant orange, aluminum powder, titanium oxide, and auramine and rhodamine One or two or more of the dye can be utilized. Pigments are preferred because they have good light fastness and good mechanical strength of the thermal transfer ink layer itself when the printed matter is used in an environment where ultraviolet rays are irradiated such as outdoor exposure.

As the thermoplastic resin, chlorinated polypropylene resin, polyamide resin, vinyl chloride resin, polyvinyl alcohol resin, acrylic resin, polyester resin, ethylene-methacrylic acid-acrylic acid copolymer,
Examples include an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, a polystyrene-polyisoprene copolymer, and a petroleum resin.

In particular, those containing a chlorinated polypropylene resin improve the various durability of the printed matter after transfer, and those using a combination of the chlorinated polypropylene resin and the polyamide resin show various durability of the printed matter after transfer. Not only improves the performance, but also for the conventional hot stamping where the transferred object needs the adhesive force of the ribbon like cellophane or nylon-based film or the surface is coated so as to inhibit the adhesive force It is preferable because good transferability can be obtained even for those that are not suitable.

An adhesive layer may be provided further outside the colored ink layer to separate the function from the colored ink layer. For the colored ink layer and the adhesive ink layer at that time, the same components as the components to be added to the colored ink layer can be used.
It is preferable not to add a coloring agent. A good effect can be obtained when a resin for improving durability and adhesion such as chlorinated polypropylene resin and polyamide resin is blended in the outermost layer.

The thermal transfer sheet of the present invention may be provided with various functional layers as long as the function of each layer described above is not substantially restricted. However, when the number of functional layers is increased, the total thickness of each layer is increased.

Further, since the thermal transfer sheet of the present invention has the above-described structure, the total thickness of each layer excluding the support can be extremely thinner than that of the conventional one. Good printed matter can be obtained without any problem such as generation of blemishes. The total of each layer excluding the support is preferably 2.5 to 6.0 μm.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermal transfer sheet of the present invention will be specifically described below.

As the support of the thermal transfer sheet, various conventionally known plastic films can be used. As the thermal transfer sheet of the present invention, a polyester film of about 6.0 to 15.0 μm can be used. If necessary, a heat-resistant lubricating layer may be provided on the back surface.

The thermal transfer sheet of the present invention is constituted by providing the above-mentioned various layers on a support. As a means for manufacturing each layer, the conventional hot stamping ribbon has a limited transfer means such as a thick layer of each layer due to its required transfer performance and cannot be coated with a gravure coater. With the above configuration, the thickness of each layer can be suppressed, and the layers can be manufactured without any particular restrictions. As a production method, a coating solution is prepared by dispersing and dissolving in a water-based or oil-based solvent to prepare a coating solution, and coating is performed to a required coating thickness by a coating method such as a gravure coater, a wire bar coater, and an air knife coater. A thermal transfer sheet can be obtained.

Since the sticking prevention layer is a layer substantially composed of a water-soluble styrene-acrylic copolymer, it is preferable to apply an aqueous coating.

When transferring with the thermal transfer sheet of the present invention, various plastic films can be used as an object to be transferred. Polyolefin films, polyester films, cellophane, nylon and the like are generally used. When a polyolefin film typified by a biaxially stretched polypropylene film is used as the transfer object, when a chlorinated polypropylene is blended in the colored ink layer or the adhesive layer of the thermal transfer sheet of the present invention, the adhesive becomes strong adhesive, and is excellent. Printing is possible. Further, when a polyester film, cellophane, nylon, or the like is used for the transfer target, when a polyamide resin, an ethylene-vinyl acetate copolymer, rosin, or the like is blended in the colored ink layer or the adhesive layer of the thermal transfer sheet of the present invention, the strength becomes strong. Adhesiveness and good printing can be obtained. However, when a polyamide resin is blended, boiling occurs for several tens of minutes in boiling water, so that it is better to use chlorinated polypropylene in combination. Further, a combination of chlorinated polypropylene and a polyamide resin is preferable because good transfer can be performed to almost all types of transfer-receiving bodies.

[0030]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to the following examples. In the examples and comparative examples, all “parts” are by weight unless otherwise specified.

Example 1 A thermal transfer ink layer component having the following composition was dispersed or dissolved in a toluene solvent on a 12 μm-thick polyester film support to obtain a solid content concentration of 1
It was adjusted to 5%, coated with a gravure coater to a coating thickness of 1.0 μm, and dried to prepare a thermal sensitivity control layer. (Thermal Sensitivity Control Layer Component) Microcrystalline wax 60 parts Polyethylene wax 30 parts Ethylene-vinyl acetate copolymer 10 parts On the thermal sensitivity control layer, a component having the following constitution was used as an anti-sticking layer with water / IPA = 2/1. Was prepared in such a manner as to have a solid content of 13%, and was coated with a gravure coater so as to have a coating thickness of 0.8 μm and dried to prepare an anti-sticking layer. (Anti-sticking layer) Water-soluble styrene-acrylic resin 100 parts (weight average molecular weight 7000) On the anti-sticking layer, as a colored ink layer, the following components were used in a solvent of toluene / IPA = 9/1. It is dispersed or dissolved to prepare a solid content concentration of 25%, coated with a gravure coater so as to have a coating thickness of 2.0 μm, and dried to prepare an anti-stick layer, and a black thermal transfer sheet is prepared. Obtained. (Colored ink layer) Chlorinated polypropylene resin 20 parts Polyamide resin 20 parts Rosin 20 parts Carbon black 40 parts

Example 2 A thermal transfer ink layer component having the following composition was dispersed or dissolved in a toluene solvent on a 12 μm-thick polyester film support to prepare a gravure coater having a solid content of 11%. Was applied to a coating thickness of 0.8 μm and dried to prepare a thermal sensitivity control layer. (Thermal Sensitivity Control Layer Component) Paraffin wax 30 parts Carnauba wax 40 parts Polyethylene wax 15 parts Ethylene-vinyl acetate copolymer 15 parts On the thermal sensitivity control layer, a component having the following composition was used as an anti-sticking layer, with water / IPA = It was dissolved in a 2/1 solvent to prepare a solid content concentration of 10%, and was coated with a gravure coater so as to have a coating thickness of 0.5 μm and dried to prepare an anti-sticking layer. (Anti-sticking layer) Water-soluble styrene-acrylic resin 60 parts (weight average molecular weight 1600) Carbon black 40 parts On the anti-sticking layer, as a colored ink layer, the following components are dispersed or dissolved in a toluene solvent. This was adjusted to a solid concentration of 23%, coated with a gravure coater so as to have a coating thickness of 1.8 μm, and dried to prepare an anti-sticking layer to obtain a black thermal transfer sheet. (Colored ink layer) Chlorinated polypropylene resin 20 parts Petroleum resin 40 parts Carbon black 40 parts

Example 3 In the same manner as in Example 2, the components having the above-mentioned constitutions were prepared so that the heat sensitivity control layer component had a solid content concentration of 30%, the sticking layer component had a solid content concentration of 25%, and the colored ink layer component had a solid content concentration. The concentration was adjusted to 35%, and each layer was sequentially formed on a support to obtain a black thermal transfer sheet. The coating thickness of each layer was 2.5 μm for the thermal sensitivity control layer, 1.5 μm for the sticking layer, and 4.0 μm for the colored ink layer, respectively, for a total of 8.0 μm.

Example 4 On the thermal sensitivity control layer of Example 1, an anti-sticking layer
The components having the following composition are dissolved in a solvent of water / IPA = 2/1 to prepare a solid content concentration of 13%, and coated with a gravure coater to a coating thickness of 0.8 μm and dried. Then, a sticking prevention layer was prepared. (Anti-sticking layer) 100 parts of water-soluble styrene-acrylic resin (weight average molecular weight 17000) On the anti-sticking layer, the same colored ink layer as in Example 1 was applied and dried to prepare an anti-sticking layer. Thus, a black thermal transfer sheet was obtained.

Comparative Example 1 The same thermal sensitivity control layer and colored ink layer as in Example 1 were sequentially applied on a support except that the anti-sticking layer of Example 1 was not applied to obtain a black thermal transfer sheet. Was.

Comparative Example 2 On the thermal sensitivity control layer of Example 1, an anti-sticking layer
The components having the following composition are dissolved in a solvent of toluene / MEK = 2/1, prepared so as to have a solid content of 13%, coated with a gravure coater to a coating thickness of 0.8 μm, and dried. Then, a sticking prevention layer was prepared. (Adhesion prevention layer) 100 parts of polyester resin On the adhesion prevention layer, the same colored ink layer as in Example 1 was applied and dried to prepare an adhesion prevention layer, and a black thermal transfer sheet was obtained.

Comparative Example 3 On the thermal sensitivity control layer of Example 1, an anti-sticking layer
The components having the following composition are dissolved in a solvent of toluene / MEK = 2/1, prepared so as to have a solid content of 13%, coated with a gravure coater to a coating thickness of 0.8 μm, and dried. Then, a sticking prevention layer was prepared. (Anti-sticking layer) 100 parts of a water-insoluble acrylic resin On the anti-sticking layer, the same colored ink layer as in Example 1 was applied and dried to prepare an anti-sticking layer, and a black thermal transfer sheet was obtained. Was.

Comparative Example 4 On a support of a polyester film having a thickness of 12 μm,
A thermal transfer ink layer component having the following composition is dispersed or dissolved in a toluene solvent to prepare a solid content concentration of 15%, and is coated with a gravure coater to a coating thickness of 1.0 μm and dried. A heat sensitivity control layer was prepared. (Thermal Sensitivity Control Layer Component) Carnauba wax 60 parts Polyethylene wax 20 parts Ethylene-vinyl acetate copolymer 20 parts Above the thermal sensitivity control layer, without a sticking prevention layer, the following components were used as a colored ink layer with toluene. It is dispersed or dissolved in a solvent to prepare a solid content concentration of 35%, coated with a bar coater so as to have a coating thickness of 8.0 μm, and dried to prepare an anti-sticking layer. A thermal transfer sheet was obtained. (Colored ink layer) Vinyl chloride-vinyl acetate copolymer 25 parts Polyamide resin 10 parts Petroleum resin 25 parts Carbon black 40 parts

The heat transfer sheet prepared as described above is mounted on a general-purpose hot stamping machine (heat stamping type), and printing is performed at a temperature of 140 ° C. using a biaxially stretched polypropylene film as a transfer object. Obtained. Table 1 shows the printing results.

[0040]

[Table 1] Here, the transferability, durability, powder removal, and sticking performance were evaluated by the following test methods. Transferability: Using a general-purpose hot stamping machine (heat stamping type), the transfer state when printing on a biaxially stretched polypropylene film at a temperature of 140 ° C. was visually checked. Durability: An adhesive tape having an adhesive strength of 900 gf / 25 mm was adhered to the transfer portion, and the change in the transfer portion after peeling off in the 180 ° direction was visually confirmed. Powder drop: Powder drop of the ink when the above-mentioned transferability test was performed 500 times continuously was visually confirmed. Sticking: At the time of the above-mentioned transferability test, sticking between the transfer sheet and the transferred body was visually confirmed.

As is clear from Table 1, all of the printed materials printed with the thermal transfer sheets of the present invention shown in Examples 1 to 4 are excellent in transferability and free from powder dropping and sticking during printing. It is a thermal transfer sheet having excellent durability of printed matter.

On the other hand, in the printing using the thermal transfer sheets of Comparative Examples 1 to 3, sticking occurs at the time of printing, and the transferability is poor. Was weak and inferior in durability.

The transferability of the thermal transfer sheet of Comparative Example 4 was excellent, but powder dropping occurred during continuous printing. Also, the durability of the printed matter was poor.

[0044]

As described above, in the thermal printing method in which the transfer layer on the support is transferred to the transfer target by the hot stamping method using thermal engraving, the thermal transfer sheet of the present invention has at least a thermal transfer sheet on the support. The sensitivity control layer, anti-sticking layer, colored ink layer, etc. are sequentially laminated, and specific components are blended into the composition, so that good printing can be performed on printing media that has a surface state that is difficult to thermally transfer. Can,
In particular, it can be satisfactorily transferred onto a transfer object of a plastic film made of polyolefin or the like used for a packaging material or the like. In addition, the image after printing is not dropped or damaged by strong mechanical abrasion, etc.
It has excellent durability that can maintain a good printing state.

Claims (6)

(57) [Claims] 1. A thermal transfer sheet comprising a support in which at least a thermal sensitivity control layer, an anti-sticking layer containing a water-soluble styrene-acrylic copolymer, and a colored ink layer are sequentially laminated. 2. The total of each layer excluding the support is from 2.5 to 6.
The thermal transfer sheet according to claim 1, which has a thickness of 0 µm. 3. The thermal transfer recording medium according to claim 1, wherein the weight-average molecular weight of the water-soluble styrene-acrylic copolymer is from 1500 to 15,000. 4. The thermal transfer sheet according to claim 1, wherein an adhesive layer is provided outside the colored ink layer. 5. The thermal transfer sheet according to claim 1, wherein the outermost layer contains chlorinated polypropylene as viewed from the support side. 6. The thermal transfer sheet according to claim 1, wherein the outermost layer contains polyamide as viewed from the support.