JPS6011391A - Heat transfer paper - Google Patents

Abstract

PURPOSE:To obtain heat transfer paper prevented from wrinkle generation caused by moisture absorption, by using paper, of which the density is 0.95-1.15, the thickness is 9-20mum and the water content is 9-15%, as the base paper for the thermal transfer paper. CONSTITUTION:Paper with density of 0.95-1.15 (JIS C2111-6.3), a thickness of 9-20mum (JIS C2111-5.1) and water content of 9-15% (JIS C2111-8) is used as base paper and coated with known wax type carbon ink to obtain heat transfer paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer paper suitably used in thermal recording devices such as thermal printers. More specifically, the present invention relates to thermal transfer paper that prevents wrinkles due to moisture absorption and prevents printing problems.

BACKGROUND ART In recent years, thermal transfer materials made by applying thermal transfer ink onto a substrate have rapidly come into use in thermal printers, thermal facsimiles, etc., and are capable of producing clear and durable images on plain paper. As a base material, PET (polyethylene terephthalate) with 6 to 9 voices is used as a plastic film, and 10~ with paper.
Capacitor paper of about 13jI is usually used.

Using 6-9s PET as a base material, apply 3-3 to 30% heat-melting ink.
5? Thermal transfer paper coated with a smear of 0.5 to 1.5 mm can produce clear and high-resolution records, but it has the following drawbacks. That is, the surface of the PET film melts when it comes into contact with the thermal head and adheres to the thermal head, which tends to cause a sticking phenomenon that causes deterioration in image quality and inability to print.

In high-speed recording where the current application time is short, the applied power is high, so the stick phenomenon is particularly noticeable.

Therefore, attempts to provide a stick prevention layer on a plastic film have been proposed, and various publications can be found.

For example, in JP-A-55-7467, a heat-resistant protective film selected from the group consisting of silicone resin, epoxy resin, melamine resin, phenol resin, fluororesin, polyimide resin, and nitrocellulose is provided on one side of a plastic film. There is something. However, the exemplified thermal transfer material is a disposable consumable material and is expensive and impractical.

For this reason, capacitor paper, which does not cause the sticking phenomenon and is inexpensive, is used, but it has the following drawbacks.

In other words, thermal transfer paper is normally loaded in the form of a roll in a thermal recording device, but when the device is stopped for a while, wrinkles tend to form near the surface of the roll due to moisture. When printing, small wrinkles will cause a decline in image quality, and large wrinkles will greatly impair the print quality.Condenser paper uses a high-freshness bulb, so it is susceptible to dimensional changes due to moisture absorption.

In general, thin paper such as Pundensa paper has a moisture content of 8% or less (usually 4 to 5%), so when used as a base material for thermal transfer paper, in a high humidity atmosphere the paper will stretch due to moisture absorption and wrinkles will appear on the rolled surface. arise.

Such wrinkles are caused by standard operating temperature and humidity of 20°C, 65%R) I
However, it easily occurs, making it difficult to use at practical operating temperatures and humidity.

However, in order to solve these drawbacks, the present inventors conducted intensive research and found that in thermal transfer materials in which hot-melt ink is applied on a base paper, the base paper has a density of 0.95 to 1.
．． 15 (JIS C2111 6.3), thickness 9-20
11 (JIS C2111 5.1), moisture content 9-15
% (8 of JIS C2111), these drawbacks can be solved and a practical thermal transfer paper can be provided, and the present invention has been completed based on the new discovery.

When the density of the base paper is less than 0.95, the paper is thin and has low physical strength such as tensile strength, which tends to cause problems in the production of thermal transfer paper, and is easy to tear while running in a printer, making it difficult to handle. Moreover, thermal transferability also deteriorates. When the density of the base paper is greater than 1.15, the amount of voids in the paper is small, so the elongation of the fibers due to moisture absorption is propagated as is, and the paper is likely to elongate and cause wrinkles.

When the thickness of the base paper is less than 9111, the physical strength is weak and it is not practical. Furthermore, if the thickness of the base paper is more than 20#, the thermal transferability will be poor and a large amount of thermal energy will be required.

When the moisture content of the base paper is less than 9%, wrinkles are likely to occur due to moisture absorption, and when it is more than 15%, the smearability of carbon ink deteriorates.

As the heat-melting ink of the present invention, a conventionally known wax-type carbon ink can be used as is.

There are no particular restrictions. The hot-melt ink used in the present invention is composed of colorants, waxes, resins, oils, and the like.

As the coloring agent, for example, in the case of black, carbon black oil black or the like can be used.

As waxes, for example, 7< rough-in wax, carnauba wax, microcrystalline wax, montan wax, low molecular weight 14y ethylene wax, hollow, beeswax, rice wax, etc. are used.

Examples of resins include ethylene copolymers, rosin derivatives,
Used for petroleum resins, styrene resins, etc.

As the oil, mineral oil, vegetable oil, etc. can be used.

Example 1 A thin paper having an absolute dry basis weight of 13.9 fl-/d was made using a softwood bulb that had been beaten to a viscous state as a bulb. After successively damping the moisture, it is passed through a super calender to a thickness x sps density 1.07 P/m% moisture content 12
% base paper was prepared.

On this base paper, 4# of heat-melting ink having a melting point of 65° C. was applied using a hot-melt coater to produce a thermal transfer paper of the present invention.

Comparative Example 1 Using a viscous-beaten softwood bulb as a bulb,
A thin paper with an absolute dry basis weight of 13.9)/j was produced. After successively damping the moisture, a base paper having a thickness of 13 tones, a density of t, o 7 t/ctfl, and a moisture content of 5% was prepared by passing through a supercalender.

A heat-melting ink was coated onto this base paper using a hot-melt coater to prepare five thermal transfer papers other than those of the present invention.

Comparative Example 2゜The absolute dry basis weight is 15.6y/11/, the density is x, 2(1/d
A thermal transfer paper other than the present invention was prepared in exactly the same manner as in Comparative Example 1 except for the following.

Comparative Example 3゜Produced in exactly the same manner as Comparative Example 2 except that the water content was 9%,
A thermal transfer paper other than the invention was prepared.

Example 2 A thermal transfer paper of the present invention was prepared in exactly the same manner as in Example 1, except that the thickness was 14.6 μm and the density was 0.95 p/m.

Example 3゜Produced in exactly the same manner as in Example 2 except that the water content was 9%.
A thermal transfer paper of the present invention was prepared.

The thermal transfer papers obtained in Examples 1 to 3 and Comparative Examples 1 to 3 above were heated at 30°C and 70°C using a Fuji Xerox printer P6.
Printing was performed under the condition of %RH.

Each thermal transfer paper was loaded in the form of a roll, and 10 copies were printed on each RPC paper.

In Examples 1 to 3, there was no printing failure due to moisture absorption wrinkles. In the case of Comparative Examples 1 to 3, printing problems occurred on the first 1 to 2 sheets due to moisture absorption wrinkles.

Claims (1)

[Claims] In thermal transfer paper having a base paper coated with hot-melt ink, use paper having a density of 0.95 to 1.15)/d, a thickness of 9 to 20 degrees, and a moisture content of 9 to 15% as the base paper. A thermal transfer paper featuring