JPS58129074A - Ink composition for forming heat-sensitive transfer layer - Google Patents

Abstract

PURPOSE:The titled ink composition, containing a polyhydric alcohol, and a thermoplastic resin, etc. a colorant and an additive, and having improved transfer ratio and resolving property. CONSTITUTION:An ink composition obtained by incorporating (A) 30wt% thermoplastic resin, e.g. polyvinyl chloride, vinyl chloride vinyl acetate copolymer, as a binder, and/or a wax, e.g. paraffin wax or polyethylene wax, as a binder, with (B) 5wt% colorant, and (C) 5wt% additive, e.g. softening agent such as mineral oil or rapeseed oil, and (D) 5wt% polyhydric alcohol, preferably ethylene glycol, polyethylene glycol or glycerol, and further 55wt% diluent.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in ink compositions for forming heat-sensitive transfer layers.

In recent years, thermal transfer recording has been developed as an output method for terminals such as computers and facsimiles due to its low noise, maintenance-free nature, simplicity of the device, and ability to be made smaller and lighter.

Conventional thermal transfer recording paper is made by coating the surface of a substrate with good thermal conductivity with a binder made of wax or other low-melting substance that softens or melts when heated, and a mixture of coloring agent. Then, combine the recording paper with the recording medium and the transfer ink layer of the transfer paper.

Conventionally, ink compositions for forming a heat-sensitive transfer layer for such recording paper, which are printed in a pattern using heat-sensitive paper, include wax, wax, low-melting point resin, etc. having a melting point of 50°C to 10°C.
It is known to coat a material at 00°C with a coloring agent such as carbon as a hot-melt coach ink, or dilute it with a solvent and a diluent, and then use a known printing method or shayufu method. .

However, recording paper for thermal transfer using the above-mentioned conventional ink composition for forming a thermal transfer layer has unfavorable transfer rate and resolution.

The present invention eliminates the above-mentioned conventional drawbacks and is based on the fact that the addition of polyhydric alcohols to the ink composition significantly eliminates the above-mentioned drawbacks.

Specifically, the present invention relates to an ink composition for forming a heat-sensitive transfer layer characterized by comprising a thermoplastic resin and/or wax, a colorant, an additive, and a polyhydric alcohol.

The structure of the present invention will be explained below. Binders include waxes such as paraffin wax, microcrystalline wax, polyethylene wax, camphorax, beeswax, white wax, and carnauba wax, vinyl chloride, and vinyl chloride-vinyl acetate copolymers. , polyvinyl butyral, various cellulose resins, acrylic resins, or petroleum resins can be used. Next, known colorants such as various pigments and dyes can be used.

Further, as additives, minerals and oils such as rapeseed oil are used as softeners. As the polyhydric alcohol, polyhydric alcohols such as glycerin, polyethylene glycol, and polyethylene glycol having a molecular weight of 200 to 6,000, preferably 300 to 1,000 are preferably used, and the coating method is preferably heated coating, but other coating methods may be used.

A heat-sensitive transfer type recording paper prepared using the above-mentioned ink composition for forming a heat-sensitive transfer layer will be explained with reference to the drawings.

FIG. 1 is a round sectional view schematically showing the state of thermal transfer recording when conventional ink is used. On the substrate 1, a transfer ink layer 2 formed from a conventional ink composition and a recording sheet 3 are combined, and thermal printing is performed using a dot 4.

In the case of conventional ink, untransferred portions 5' corresponding to the transfer printing portions 5 remain on the substrate IT/C, and the image quality is poor in resolution due to a poor transfer rate.

FIG. 2 is a diagram showing a case in which a transfer ink layer 2I is formed using the ink composition of the present invention. By adding the polyhydric alcohol, the transfer rate is improved as shown in the transfer printing section 7, and the pattern of the thermal head can be faithfully reproduced as shown in 8.

In the present invention, the base sheet 1 may be any material as long as it has a strength that will not stretch or tear during use and will not be deformed or partially melted by the heat of a recording thermal head, such as polyester.

These include polypropylene, polystyrene, polycarbonate, polyimide and other plastics, film, glassine paper, capacitor paper, ledger paper, Indian paper and other papers, metal foil, and composites of the above materials. KL-paper composite sheets, metallized paper or metallized films are used.

Hereinafter, this will be explained in detail using examples.

Example 1 A transfer ink composition having the composition below a polyester film KB having a thickness of 6 μm was heated to 80° C. and roll coating was performed. Dry solids content was 4'I/rl.

The coated surface of this transfer paper was printed using a thermal printer manufactured by Shinko Electric Co.
When I passed it along with P3080K polyester film, I was able to get a black print with good image quality.

Comparative Example 1 A transfer paper was produced in the same manner as in Example 1 except for using the ink composition of Example 1 except that glycerin was removed, and the resulting transfer paper was used to print on a matte polyester film. The transfer rate of the printed portion was low, resulting in a so-called drop-through condition in the petal portion.

Example 2 Transfer ink compositions of the following colors were printed on a condenser paper having a thickness of 8 μm using a four-color gravure printing machine. At this time, the dry coating amount was 5P or more for each color ink.

Coloring material; Key CI 21090. Aka = CI 15850
I-CI 7416G, Crocarbon Grass, Riko's transfer paper, and calendered and smoothed high-quality paper were combined into a thermal printer and passed through a printing machine equipped with Do (manufactured by Toshiba), and the printed area was printed in 4 colors. Good image quality with sharp pattern edges and color-coded patterns was obtained.

Comparative Example 2 Transfer paper was produced in the same manner as in Example 2 using the ink composition of Example 2 except that polyethylene glycol was removed, and printing was performed on high-quality paper. However, the transfer rate of the printed portion was poor, leaving an ink film on the base paper, and the printing quality was poor.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing printing using a heat-sensitive transfer type recording paper formed using a conventional ink composition and FIG. 2 using an ink composition of the present invention. 1...Base sheet 2...Transfer ink layer 3...Recording sheet 4...Printing For business, door 5 open Show 58-129074 (3)

Claims (1)

[Claims] (1) An ink composition for forming a thermal transfer layer, characterized by comprising a thermoplastic resin and/or wax, a colorant, an additive, and a polyhydric alcohol. f21 polyfffr alcohol is ethylene glycol,
An ink composition for forming a heat-sensitive transfer layer according to claim 9, fl+, characterized in that it is polyethylene glycol or glycerin.