JPS6395990A - Thermal transfer recording material - Google Patents

Abstract

PURPOSE:To prevent defective transferring such as transfer of missing images, by coating a base with a coating agent comprising a polyester resin, a polyethylene wax and hydrophobic silica as essential constituents to produce a thermal transfer ink-receiving layer. CONSTITUTION:A polyester resin, a polyethylene wax and hydrophobic silica are dissolved or dispersed in a dispersant such as toluene and perchloroethylene to prepare a coating liquid. The coating liquid is applied to a base such as a polyethylene terephthalate film to provide a thermal transfer ink-receiving layer, thereby producing a thermal transfer recording material. The polyester resin is preferably a thermoplastic saturated polyester resin having a high molecular weight of 5,000-500,000. The polyethylene wax preferably has a molecular weight of 900-4,000, and the hydrophobic silica preferably has several hundreds to several thousands of silanol groups per primary particle of hydrophilic SiO2.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a new recording material for thermal transfer, and in particular, it is capable of providing extremely clear character and image printing quality using a thermal transfer color printer or the like. The present invention relates to a recording material suitable for overhead projects (hereinafter referred to as OHP).

(Prior art) The heat melt transfer method, which is one of the heat transfer recording methods, involves superimposing an ink ribbon having a heat melt ink layer on a recording material to print patterns such as letters and figures on the ink ribbon.
In this method, the ink ribbon is heated with a heating pattern to transfer the heat-melting ink from the ink ribbon to the recording material.

On the other hand, in an OHP in which characters, figures, etc. on the sheet are projected onto a screen by transmitting light through the sheet, the above-mentioned heat-melt ink transfer method is used to create the sheet.

In this case, the conventional recording materials used as sheets for OHP are transparent films coated with a rubber adhesive layer or acrylic adhesive layer, or coated layers containing a solid wax that is compatible with hot melt ink (# No. 50-154096) etc. have been used and proposed.

(Problem to be solved by the invention) However, as thermal transfer printers capable of high-speed printing have been developed in recent years, improvements in the clarity of print quality associated with high-speed printing have also been required for recording materials. or are not sufficiently meeting these demands.

In particular, in OHP sheets, when the ink-receiving layer is composed only of organic polymer materials as in the prior art, when recent high-speed printing models are used, some or all of the characters may be missing or solid. When printing, ink transfer is insufficient, leading to transfer defects such as sharp or irregular edges, blurring, or almost no transfer, making it difficult to obtain stable print quality. There is.

Of course, as a solution to this problem, many improvements have been made to ink ribbon inks, but so far nothing satisfactory has been achieved. In particular, when an ink ribbon compatible with plain paper is used, the print quality further deteriorates with the conventional film processing method.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a recording material in which a coating material for forming a thermal transfer ink receiving layer is coated on a base material, This paper proposes a thermal transfer recording material whose coating material includes polyester resin, polyethylene wax, and hydrophobic silica as essential components.

The polyester resin that can be used in this invention is a thermoplastic high molecular weight saturated polyester resin, with a molecular weight of 5000 to 500,000, preferably 10.000.
~50,000 is suitable.

Next, the polyethylene wax is low molecular weight polyethylene obtained by direct polymerization of ethylene, and has a molecular weight in the range of several hundred to several thousand, but one having a molecular weight of 900 to 4,000 is preferable.

Furthermore, hydrophobic silica has hundreds to thousands of silanol groups in one hydrophilic SiO2 primary particle, and these silanol groups can be treated with a silane compound to make them hydrophobic, which is particularly preferred. The material was treated using trimethylchlorosilane as a silane compound.

In addition, curing agents and crosslinking agents such as melamine, isocyanate, etc. may be added for the purpose of improving film strength.

Regarding the blending ratio of polyester resin, polyethylene wax, and hydrophobic silica, there was a tendency that when the proportion of polyethylene wax was relatively small, the printing performance decreased, and when it increased, the strength of the coating film decreased.

In addition, hydrophobic silica improves adhesion with ink by increasing the physical adhesion area due to the unevenness of the coating surface.
In the heated area, the heat from the heated area is not easily transmitted due to the heat insulating effect of the surface unevenness, which has an excellent effect on improving printing quality such as sharpening the printing edge surface.
If the amount added increases, powder dropout tends to occur, and if it decreases, printing performance deteriorates.

Based on the above-mentioned trends of each component, the blending ratio of these components is within a range not exceeding 3 parts by weight of polyethylene wax, preferably 0.1 to 3 parts by weight, and 5 to 50 parts by weight of hydrophobic silica to 10 parts by weight of polyester resin. They may be blended within a certain range, and a dispersion medium may be added to this as appropriate to obtain a coating material in the form of a solution.

The dispersion medium used here may be any one that is compatible with the polyester resin and polyethylene wax and that can uniformly disperse hydrophobic silica, such as petroleum solvents such as toluene and xylene, polar solvents such as MEK and DMF, 1.
1. Chlorinated solvents such as 1-trichloroethane, trichlorethylene, perchlorethylene, etc. can be used.

The substrate used for the recording material for thermal transfer of this invention should be specified depending on the use of the recording material, and the recording material for thermal transfer for OHP, which is one of the objects of this invention, is a transparent plastic sheet. For example, transparent films such as polyethylene terephthalate, polycarbonate, polyacetal, etc. are used, and in particular, biaxially oriented polyethylene terephthalate with a film thickness of 25 to 10071
The film thickness may be determined as appropriate depending on the characteristics and purpose of the printer.

The film thickness when coating the above-mentioned coating material on a base material is a dry thickness of 0. It is sufficient to have OIILm or more, and 0.05 to 3 JLm is appropriate when considering performance, economy, etc.

The coating method may be an air knife coater, bar coater, reverse coater, gravure coater, hot melt coater, or the like.

(Effects of the Invention) In summary, the recording material according to the present invention has a thermal transfer ink-receiving layer formed by coating the substrate surface with a coating consisting of polyester resin, polyethylene wax, and hydrophobic silica. This method almost eliminates transfer defects such as missing part or all of printed characters, and the thermal transfer ink is absorbed accurately. Therefore, even when using a high-speed printer, it is possible to obtain stable, extremely clear, high-quality printing.

In addition, when a transparent base material is used as a base material, the coated surface is physically strong and stable, and the recording material has excellent printing characteristics without adversely affecting its transparency. It is suitable as a thermal transfer recording material for OHP.

(Example) Examples of this invention will be shown below.

Example 1 Coating agents of various compositions were applied to a 50 JLm thick film of polyethylene terephthalate [manufactured by Toshi Co., Ltd., trade name Lumirr T] as a base material using a bar coater #5, and dried at 130°C for 30 seconds to make it transparent. A thermal transfer coating was prepared and its printing performance, haze, powder removal, and film strength were evaluated.

The evaluation criteria were as follows, and the composition of the coating material and the evaluation results are shown in Table 1.

Evaluation criteria (1) Printing performance: NEC thermal transfer printer PC-PR
-101T and the same printer PC-PR-101TL, the print or transfer was very clear ◎, the two models were fairly clear and good ○, 1
△ if only the model is good, × if both 2I types are bad
And so.

(2) Haze (transparency): Judging on OHP, comparing the transparency with that of the same base material without coating, ○ indicates the same transparency, and ○ indicates the same level of transparency. ×

(3) Powder removal: When the coated surface was rubbed with a finger, those that did not come off were marked as O1, those that peeled off a little, and those that peeled off indefinitely were marked as ×.

(4) Film strength: When the coated surface was rubbed with a fingernail, the coated surface did not peel off as ○, the coated surface peeled off a little as Δ, and the coated surface that peeled off easily as x.

Table 1 It can be evaluated that No. 6 to 10 and No. 14 to 19 in Table 1 above are the optimal results. From these results, it is clear that there is a tendency in performance depending on the blending ratio of polyethylene wax and hydrophobic silica to polyester in the coating material.
Good results have been shown when the amount of polyethylene wax does not exceed 3 parts by weight per 10 parts by weight of the polyester resin.

Example 2 A coating material having the composition shown in the following formulation example and comparative example was prepared, and a recording material was prepared in the same manner as in Example 1, and its properties were evaluated and shown in Table 2.

Blend example (1) Incyanate cross-linked polyester resin (
Atcoat 76H5:CAT] 0=100:6.5. (manufactured by Toyo Morton Co., Ltd.) 10 parts by weight Polyethylene wax (Hiwax 11011A, manufactured by Mitsui Petrochemicals) 0.25 parts by weight Hydrophobic silica (IIDK H-15 manufactured by WACHER) Add toluene to a composition of 35 parts by weight or more to solidify The minute concentration was set to 2.0z.

(2) Polyester resin (Kemit 1089 manufactured by Toshisha) 10 parts by weight Polyethylene wax (Hiwax 4252E manufactured by Mitsui Petrochemicals) 1 part by weight Hydrophobic silica (HDK H-2000 WACHER) 15 parts by weight or more Toluene was added to make the solid content concentration 2.5z.

(3) Polyester resin (Kemit KG682 manufactured by Toshisha Co., Ltd.) 10 parts by weight polyethylene wax (Hiwax 200MP).

1 part by weight hydrophobic silica (Aerosil R-812 manufactured by Nippon Aerosil Co., Ltd.)
Toluene was added to the composition of 2 parts by weight or more to give a solid content concentration of 1.5z.

(4) Polyester resin (Kemit KG682 manufactured by Toshi Co., Ltd.) 10 parts by weight Polyethylene wax (Hiwax 100pH manufactured by Mitsui Petrochemicals Co., Ltd.) 1 part by weight Hydrophobic silica (HDK H-2000/4 WACHE) manufactured by 1 company) 1
Solid content concentration by adding toluene to the composition of 5 parts by weight or more],
It was set at 75%.

Comparative Example (1) Polyester resin (Vylon 20, manufactured by Toyobo Co., Ltd.) 1 part by weight Wax (Montan Hiwax S, manufactured by Bequist Co., Ltd.) At least 1 part by weight of toluene was added to the composition to make the solid content concentration 2.52.

(2) Wax (Hiwax), +05A, manufactured by Mitsui Petrochemicals Co., Ltd.) 100 parts by weight Hydrophobic silica (Aerosil l?-972B manufactured by Hon Aerosil Co., Ltd.) Toluene is added to the composition of 5 parts by weight or more to solid content concentration 2 ．． It was set as Ol.

(3) For BLAN: The base material is intact and no coating material is applied.

Table 2

Claims (2)

[Claims] (1) A recording material formed by coating a base material with a coating agent that forms a thermal transfer ink-receiving layer, and the coating agent is composed of polyester resin, polyethylene wax, and hydrophobic silica as essential components. A recording material for thermal transfer characterized by: (2) The recording material for thermal transfer according to claim 1, wherein the base material is a transparent plastic sheet material.