JPH059277B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an ink sheet used, for example, in thermal transfer printing.

[Prior art and its problems]

2. Description of the Related Art In recent years, various image reproducing devices such as home video and computer graphics have become widespread, and along with this, it has been desired to print reproduced image information. As such printing devices, for example, wire dot type, inkjet type, or thermal transfer type printing devices are being developed. Among these various printing devices, thermal transfer printing devices have features such as a simple mechanism, easy handling, low noise, and the ability to produce printed matter with good gradation. It is said that it does. The principle of printing using this thermal transfer printing device is as follows:
An ink sheet with a heat-sublimable ink layer provided on one side of the substrate and a receiving sheet are stacked together so that the receiving sheet and the ink layer of the ink sheet face each other, and the thermal head of a printing device is used, for example, from the substrate side of the ink sheet. It is heated to sublimate the sublimable dye in the ink layer of the ink sheet and transfer it to the receiving sheet. The ink layer in such an ink sheet is
It is well known that ink sheets are required to have excellent heat resistance and excellent storage stability, and in addition to these requirements, ink sheets are also required to be easy to handle. From this point of view, in order to construct an ink layer that is easy to handle and has excellent heat resistance and storage stability, research has focused on the binder, which is an important component of the ink layer. various proposals have been made. For example, an ink sheet in which the ink layer is composed of a natural or synthetic resin having a volatile dye and a reactive functional group, and a crosslinking agent (Japanese Patent Application Laid-Open No. 58-215397), or a photocured product of oligoacrylate or an aromatic An ink sheet composed of a photocured product of an epoxy resin and a sublimable dye using a group diazonium salt catalyst (Japanese Unexamined Patent Publication No. 178294/1982), or an ink sheet using polyvinyl butyral resin as a binder for forming an ink layer (Japanese Patent Application Laid-open No. 178294/1983), 1986-101087) etc. have been proposed. However, conventional dye-sublimation ink sheets,
Unlike heat-melting ink sheets, sublimable dyes have poor light resistance and sublimate when placed at high temperatures, so they are hardened using heat or light when forming the ink layer. If this is done, color fading may occur or the dye itself may sublimate, so transfer prints using such sublimation ink sheets still have the problem of low print density. Furthermore, although ethyl cellulose, cellulose acetate propionate, polyvinyl butyral, and saturated polyester resins have excellent heat resistance, when these resins are used as binders for ink layer composition, Due to its poor oil resistance, the problem of being attacked by the fat on your hands remains unresolved.

[Disclosure of the invention]

The present invention has been made in view of the above-mentioned problems, namely, it not only has excellent heat resistance and storage stability, but also is not attacked by lipids and the like, and the ink sheet is easy to handle. Furthermore, it was made as a result of intensive research into an ink sheet that can increase the printing density of transfer printed matter, and it is made of at least one selected from the group of polyvinyl butyral, ethyl cellulose, cellulose acetate propionate, and saturated polyester resin. A sublimation ink layer made of an epoxy resin and a sublimable dye is provided on a substrate, and the epoxy resin has a number average molecular weight of 10,000 or more, and the polyvinyl butyral resin, etc. The ratio of at least one resin selected from the group to the epoxy resin is 90 to 90 by weight.
It provides ink sheets set at 20:10 to 80:00. The molecular weights of polyvinyl butyral, ethyl cellulose, cellulose acetate propionate, and saturated polyester resins used in the present invention are selected from the viewpoint of adjusting the viscosity to a desired value during application of the paint for forming the ink layer. However, it has never been said that the properties of an ink sheet will deteriorate significantly unless the ink sheet has a special molecular weight, whereas the number average molecular weight of epoxy resins is approximately 10,000 or more. is particularly preferred. That is, when an epoxy resin having a number average molecular weight considerably smaller than 10,000 was used, properties such as heat resistance, oil resistance, and print density tended to be inferior. In addition, the ratio of at least one resin selected from the group such as polyvinyl butyral resin and epoxy resin should be such that the former: the latter = 90 to 20: 10 to 80 in terms of oil resistance and printing density. It is desirable that there be one. Further, as the sublimable dye used in the present invention, suitable dyes such as basic dyes or disperse dyes such as azo-based, anthraquinone-based, styryl-based, quinophthalone-based, and nitrodiphenylamine-based dyes are used. In addition, as the substrate used in the present invention,
Polyester resins such as polyethylene terephthalate and polycarbonate, cellulose resins such as acetylcellulose and cellophane, polyvinylidene fluoride, ethylene tetrafluoride-propylene hexafluoride copolymer, fluorine resins such as Teflon,
Appropriate resins such as polyether resins such as polyoxymethylene and polyacetal, olefin resins such as polypropylene, and imide resins such as polyimide and polyetherimide are used. Then, on one side of such a substrate, a coating material containing a resin selected from the group such as the sublimable dye, epoxy resin, and polyvinyl butyral is applied in a layer of about 0.1 to 3 μm.
The ink layer is formed by applying the ink layer to a thickness of about m. The solvent for forming such a paint may be any solvent that dissolves the epoxy resin and has appropriate volatility, such as xylene, cyclohexanone, methyl ethyl ketone, toluene, ethyl acetate, ethyl cellosolve, etc. is used. In addition, in order to improve the sensitivity during transfer printing, it is desirable that the sublimable dye be uniformly dispersed in a binder made of epoxy resin, etc. It is desirable that the resin etc. be sufficiently dispersed. In order to obtain such sufficient dispersibility,
It is desirable that the epoxy resin has a number average molecular weight of about 200,000 or less. In addition, in order to prevent the sticking phenomenon in which the thermal head of the printing device and the substrate are welded together, a heat-resistant protective film may be provided on the other surface of the substrate opposite to the side on which the ink layer is formed, if necessary. be. Further, an adhesive layer may be provided between the substrate and the ink layer.

[Example 1] The number average molecular weight represented by the above structural formula is approximately 12,000
5 parts by weight of epoxy resin, 5 parts by weight of BX-1 (polyvinyl butyral manufactured by Sekisui Chemical), 20 parts by weight of Kayaset Blue 714 (sublimable dye manufactured by Nippon Kayaku),
After dispersing 170 parts by weight of methyl ethyl ketone and 30 parts by weight of cyclohexanone in a ball mill for 1 hour,
Apply this paint to a specified thickness on one side of a 4.5 μm thick polyethylene terephthalate film and let it dry.
An ink layer with a thickness of 1 μm is provided. Next, a coating containing 3% by weight of silicone resin (KS-841 manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the other side of the polyethylene terephthalate film to a coating thickness of 0.3 μm, and the other side was coated with heat-resistant protection. An ink sheet according to the present invention provided with a film is obtained.

Example 2 The same procedure as in Example 1 was carried out using an epoxy resin having a number average molecular weight of about 60,000 to obtain an ink sheet according to the present invention.

Example 3 The same procedure as in Example 1 was carried out using an epoxy resin having a number average molecular weight of about 180,000 to obtain an ink sheet according to the present invention.

[Example 4] In Example 2, 1 part by weight of epoxy resin,
The same procedure was carried out using 9 parts by weight of BX-1 to obtain an ink sheet according to the present invention.

[Example 5] In Example 2, 4 parts by weight of epoxy resin,
The same procedure was carried out using 6 parts by weight of BX-1 to obtain an ink sheet according to the present invention.

[Example 6] In Example 2, 8 parts by weight of the epoxy resin,
The same procedure was carried out using 2 parts by weight of BX-1 to obtain an ink sheet according to the present invention.

[Example 7] In Example 2, N-50 was used instead of BX-1.
The ink sheet of the present invention is obtained in the same manner using ethylcellulose (Hercules Co., Ltd.).

[Example 8] In Example 2, CAP-1 was used instead of BX-1.
482-0.5 (cellulose acetate propionate manufactured by Eastman Co.) was carried out in the same manner to obtain an ink sheet according to the present invention.

[Example 9] In Example 2, Byron was used instead of BX-1.
290 (a saturated polyester resin manufactured by Toyobo Co., Ltd.) was similarly carried out to obtain an ink sheet according to the present invention.

[Example 10] The same procedure as in Example 2 was carried out using 4 parts by weight of BM-2 (polyvinyl butyral manufactured by Sekisui Chemical Co., Ltd.) and 1 part by weight of Byron 290 in place of 5 parts by weight of BX-1. Obtain an ink sheet.

[Comparative Example 1] The same procedure as in Example 2 was carried out except that the epoxy resin was changed to 10 parts by weight, but BX-1 was not used at all, and an ink sheet was obtained.

[Comparative Example 2] The same procedure as in Example 2 was carried out except that no epoxy resin was used and BX-1 was used in an amount of 10 parts by weight to obtain an ink sheet.

[Comparative Example 3] The same procedure as in Example 7 was carried out except that no epoxy resin was used and N-50 was added to 10 parts by weight to obtain an ink sheet.

Comparative Example 4 The same procedure as in Example 8 was carried out except that no epoxy resin was used and CAP-482-0.5 was used in an amount of 10 parts by weight to obtain an ink sheet.

[Comparative Example 5] The same procedure as in Example 9 was carried out without using any epoxy resin and with 10 parts by weight of Vylon 290.
Get an ink sheet.

[Comparative Example 6] Aronix M5700 (epoxy acrylate, monomer or oligomer form manufactured by Toagosei Chemical Industry Co., Ltd.) was used instead of the epoxy resin in Example 2.
and apply a paint containing such epoxy acrylate and dye in the same manner as in Example 1,
After drying, it is cured by irradiating it with an 80W ultraviolet lamp for 3 seconds, and then an ink sheet is obtained in the same manner.

【Characteristic】

The ink sheets obtained in each of the above examples were stacked so that the ink layer of these ink sheets and the receiving sheet faced each other, and a polyethylene terephthalate film was applied from the heat-resistant protective film side to a heating resistor density of 8 dots/mm. Transfer printing is performed by applying a power of 0.6 mJ per dot to a thermal head with
The storage stability and oil resistance were investigated and the results are shown in the table. The receiving sheet was made of polypropylene synthetic paper coated with polyester resin to a thickness of 6 μm. Then, print density is measured using Macbeth Densitometer (model number RD).
-918) and expressed as a ratio to that of Comparative Example 1.The heat resistance evaluation is based on the property that no sticking occurs between the ink sheet and the receiving sheet during transfer printing. The ○ marks indicate those that have stuck, and the × marks indicate that the ink sheet has stuck.
Leave it in an atmosphere with 90% humidity at ℃ for 24 hours, and mark ○ if there is no abnormality in the ink layer, mark × if the dye is agglomerated, or mark if the dye is slightly agglomerated. The oil resistance is evaluated by applying squalane to the ink layer and applying 20
The ink layer remains unchanged after a period of time with a mark ○, the dye in the ink layer is dissolved and aggregated with an x mark, and the dye with some aggregation is marked with a triangle.

[Table] As can be seen from the following, when transfer printing was performed using the ink sheet of this example obtained without substantially performing heat or photocuring treatment on the ink layer structure, the print density was high; The printing properties of the resulting printed matter are excellent. That is, compared to Comparative Example 6 in which the ink layer was formed by irradiation with light, the print density was improved by about 30%, and in addition, compared to Comparative Example 6 in which only epoxy resin was used as a binder without using polyvinyl butyral or the like. Even compared to No. 1, the print density is improved by about 10 to 20%. Furthermore, during transfer printing, no sticking phenomenon occurs between the ink sheet and the receiving sheet, and therefore damage accidents such as breakage of the ink sheet or the receiving sheet occur when the receiving sheet is peeled off from the ink sheet after transfer printing. Furthermore, even if such an ink sheet is stored in a bad environment, the ink layer is unlikely to deteriorate and has excellent storage stability. In addition, it has excellent oil resistance, meaning that even if the ink sheet is handled with dirty hands, the ink layer is unlikely to deteriorate, and the printing properties are unlikely to deteriorate, making it easy to handle. be. On the other hand, although the same epoxy resin is used in the composition of the ink layer, if a resin selected from the group such as polyvinyl butyral is not used, as shown in Comparative Example 1, the ink layer Although it has excellent properties such as heat resistance, storage stability, and oil resistance, the print density is lower than that of the present invention, probably because the binding power of the sublimable dye by the binder is too strong. In addition, no epoxy resin is used in the composition of the ink layer,
When polyvinyl butyral resin is used, as shown in Comparative Example 2, the printing density is high as in the case of the present invention, but the storage stability is poor, and therefore, printing using polyvinyl butyral resin that has been stored for a long time in a bad environment is not possible. In this case, the high density printing characteristics shown in the table cannot be obtained. Furthermore, the ink sheet of Comparative Example 2 also has poor oil resistance, making it difficult to handle. In addition, even if ethyl cellulose, cellulose acetate propionate, saturated polyester resin, etc. are used in the composition of the ink layer, if an epoxy resin is not used, as shown in Comparative Examples 3, 4, and 5, the composition of Comparative Example 2 The ink sheet is similar to the ink sheet of the present invention, and is much inferior in width to the ink sheet of the present invention. In addition, when the ink layer is formed by photocuring, that is, when the binder of the ink layer is like that of Comparative Example 6, the print density is low and the printing characteristics are different from those of this example. It has a very low fatal flaw.

【effect】

The ink sheet according to the present invention is a sublimation type ink sheet made of at least one selected from the group of polyvinyl butyral, ethyl cellulose, cellulose acetate propionate, and saturated polyester resin, an epoxy resin, and a sublimable dye as a base material. The epoxy resin has a number average molecular weight of 10,000 or more, and the ratio of the epoxy resin to at least one resin selected from the group such as the polyvinyl butyral resin is by weight. 90-20: Since the setting was 10-80, the printing density of the printed matter by transfer printing using this ink sheet is high, and the ink sheet and the receiving sheet are less likely to stick together during transfer printing. The ink sheet and the receptor sheet are less likely to be damaged such as breakage when the ink sheet and the receptor sheet are separated after transfer printing, and the ink layer is less likely to deteriorate even when placed in an adverse environment. Therefore, it is now possible to provide printed matter with excellent printing properties, and since the ink layer of this ink sheet is highly oil-resistant, the transfer printing properties are unlikely to deteriorate even when handled with dirty hands. The ink sheet is easy to handle, and the ink sheet can be replaced smoothly during transfer printing.

Claims (1)

[Claims] 1. Polyvinyl butyral, ethyl cellulose, cellulose acetate propionate,
and a sublimation ink layer composed of at least one type selected from the group of saturated polyester resins, an epoxy resin, and a sublimable dye,
The epoxy resin has a number average molecular weight of 10,000 or more, and the weight ratio of the epoxy resin and at least one resin selected from the group such as the polyvinyl butyral resin is 90 to 20:10 to 80.
An ink sheet characterized by being set to.