JPS59148693A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium capable of preventing troubles of paper feeding with charge on the recording medium when a synthetic paper or synthetic resin film free of paper dust as a supporter for the thermal recording medium. CONSTITUTION:A thermal color forming layer containing a color forming substance and a developer to form color upon reaction with the color forming substance under heated condition is provided at least one side of the following supporter to obtain a desired thermal recording medium. The supporter is a synthetic paper or a synthetic resin film, whose surface to be coated with the thermal layer has a surface resistance value of 5X10<10>OMEGA or less in the atmosphere of 65%RH of 20 deg.C and the surface not to be coated with the thermal layer has a surface resistance value of 1X10<12>OMEGA or less.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording medium, and more specifically, the present invention relates to a heat-sensitive recording medium, and more specifically, to a method for solving paper feeding problems that occur due to charging of the recording medium when synthetic paper or synthetic resin film is used as a support for the thermal recording medium. The feeling of preventing such problems m1. @Regarding recording bodies.

2. Description of the Related Art Heat-sensitive recording materials in which a heat-sensitive color-forming layer containing a color-forming substance and a color-developing substance that develops color by reacting the color-forming substance with heat on a support are well known.

Such a /j8 thermal recording material is easy to maintain, has no odor and noise during recording, and has secondary color development, etc.
It is widely used as a recording medium for facsimiles, printers, etc.

Conventionally, paper has been mainly used as a support for these thermal papers. However, recently, the range of use of thermal paper has expanded, and it has come to be used in clean rooms and the like. When conventional thermal paper with paper as a support is used for such purposes, it generates paper dust and cannot be used in clean rooms where even the slightest dust is undesirable. Therefore, various heat-sensitive recording materials using synthetic paper or synthetic resin film as a support that do not generate paper dust have been considered.

Such a heat-sensitive recording material has the advantage of not generating paper dust (and is highly smooth, resulting in good dot reproducibility, high speed and halftone reproducibility, and good water resistance.

However, synthetic paper or synthetic resin film generally has higher electrical resistance, especially volume resistivity, than paper, and thermosensitive recording materials using these as a support are prone to paper feeding problems due to their chargeability. There is a drawback.

Conventional Japanese Unexamined Patent Publication No. 57-156292, No. 57-170794
, No. 57-199687, etc., various proposals have been made to solve paper feeding problems caused by charging. JP-A-57-156292 discloses a method in which a conductive material is contained in the recording layer or support, but when the conductive agent is contained in the recording layer, wear of the thermal head increases and
There are some drawbacks.

Furthermore, JP-A-57-170794 discloses a method in which a conductive material is coated on the back side of a heat-sensitive recording medium, but this type of recording medium does not have a sufficient antistatic effect when the support is a film or synthetic paper. Sarahi JP-A No. 57-199'687 uses a conductive base material as a support, but when the support is a film, it is not easy to uniformly disperse the conductive substance, and the volume resistivity value is low. 5 at 20℃654R)-1
It is difficult to make it less than ×10100·α.

The present inventors have conducted extensive research in order to solve the above-mentioned drawbacks and solve paper feeding problems caused by charging when synthetic paper or synthetic resin film is used as a support for a heat-sensitive recording medium, and as a result, the present invention has been developed. I arrived at the eggplant. That is, the present invention provides a heat-sensitive recording material in which a heat-sensitive color-forming layer containing a color-forming substance and a color-developing substance that develops color by reacting the color-forming substance with heat is provided on at least one surface of a support, The support is synthetic paper or synthetic resin film, and the surface resistance of the surface of the support to which the heat-sensitive layer is coated is 65% l at 20°C.
(, l() in an atmosphere of 5×10 10 Ω or less, and the surface resistance of the surface not coated with a heat-sensitive layer is ]X] 0 12 Ω or less.

The synthetic paper used as a support in the present invention is a synthetic resin film that has a string-like appearance and physical properties.
It does not include synthetic fibers made by wet or dry processes. Methods for manufacturing such synthetic paper include coating the surface of a synthetic resin film with a white pigment, and adding fillers or foaming agents to the synthetic resin film to make it opaque. It can be used as a support for inventions.

Further, the synthetic resin film used as a support in the present invention includes conventionally known synthetic resin films, evaporated polyester films, polyolefin films, cellulose films, polyamide films, etc. ().

K is the value expressed by 6iI of the surface electrical resistance value of the surface of the support.
This is carried out by applying a conductive substance to the surface of the support with or without a binder, and fixing it by methods such as dipping, evaporation, etc.

The present invention may be used as a substance (
・Inorganic electrolytes such as potassium chloride, calcium chloride, lithium chloride, alum ■Sulfates, sulfonates, carboxylates, phosphates,
Increased alkyl sulfonic acid, alkylaryl sulfonate,
naphthalene sulfonate, naphthalene disulfonate,
Anionic surfactants such as salts of formalin condensates ■Cationic surfactants such as alkyltrimethylammonium salts, alkyldimethylammonium salts, alkyldimethylbenzylammonium salts, alkylhyricinium salts■Polyethylene glycol, polypropylene Nonionic surfactants such as polyethers such as glycols and polyhydric alcohols; Ampholytic surfactants such as compounds with long-chain aliphatic groups, quaternary ammonium nitrogen, and carboxyl or sulfone groups (6) -y /l/ Mini lamb powder, copper powder, zinc powder, carbon black, graphite, silica, alumina powder,
Polymer electrolytes such as inorganic materials such as copper iodide, tin oxide, and zinc oxide, such as polydimethyldiallylammonium chloride, polyvinylbenzyltrimethylammonium chloride, and oligostyrene sulfonates. ■Organic semiconductors such as carbazole complexes and thiazine complexes ψ. Metal powder, carbon black, impurity-doped zinc oxide, tin oxide, etc. are preferable because of their small resistance change.

The binder used with the conductive material is not particularly limited, including polyvinyl alcohol, and may be water-soluble or solvent-based as long as it meets the purpose of the present invention.However, the binder on the heat-sensitive layer side may be water-resistant. Or preferably one that can be made water resistant.

A commonly used method can be used to coat a support with a heat-sensitive paint to obtain a heat-sensitive recording material. The heat-sensitive layer is provided on one side of the support, and in some cases on both sides. In this case, it is necessary that the surface resistance value of both surfaces of the support be 5×]012Ω or less.

The present invention will be explained in more detail below by giving Examples and Comparative Examples.

Example 1 Conductive tin oxide (manufactured by Nihon Kagaku Sangyo 5IDO-200) 9
0 parts, ammonium polyacrylate 20 parts circulating water solution, 2 parts, polyvinyl alcohol 12 parts aqueous solution 30 parts, and water 11 parts
3 parts were dispersed in a paint shaker for 5 hours, and after the dispersion, 30 parts of polyvinyl alcohol 12 circulating solution and 20 parts of dialdehyde starch 12 circulating solution were added to prepare a coating liquid for conductive treatment. This coating liquid was coated on commercially available synthetic paper (FPq-1+60 manufactured by Tamago Yuka Synthetic Paper, surface resistance 8.5 x 10"Ω).
) on one side of about 7 f/ltr? The coating was applied to a solid content and dried to obtain a support.

Next, Part A Crystal Violet Lactone 5 parts Zinc stearate 10 parts Calcium carbonate
27 parts polyacrylic acid] O'll+
Aqueous solution 5 parts polyvinyl alcohol 12 parts aqueous solution
30 parts water
50 parts Solution B 4.4'-isopropylidenediphenol 15 parts Calcium carbonate 27 parts Sodium polyacrylate 10% water solution 5 parts Polyvinyl alcohol 12
Aqueous solution 30f! A water
Disperse 50 parts separately in a paint shaker for 12 hours, then add 1 part polyvinyl alcohol.
A heat-sensitive coating liquid was prepared by adding 65 parts of a two-width aqueous solution.

This heat-sensitive coating liquid was applied to the side of the support coated with the conductive treatment liquid to a solid content of approximately 7 fl/m and dried to obtain a heat-sensitive recording material. Body band?lf characteristics are shown in Table 1.

Example 2 The conductive treatment liquid of Example was applied to both sides of a polyethylene terephthalate film having a thickness of 50 μm so that the solid content was approximately 79/J to obtain a support. One side of this support was coated with the heat-sensitive coating solution of Example 1 with a solid content of about 7 F//n? Table 1 shows the surface resistance value of the support and the chargeability of the heat-sensitive recording material.

Example 3 Conductive zinc oxide (ZEO manufactured by Nippon Kagaku Sangyo) was used in place of the conductive tin oxide used in the coating liquid for conductive treatment in Example 1, and the other conditions were the same as in Example J. A coating liquid was obtained. This coating liquid was applied to both sides of a polyethylene terephthalate film with a thickness of 50 μm so that the solid content was approximately 7 f/m'', and the support was coated with a brown color. The heat-sensitive recording material was coated to a coating thickness of about 722 cm.The surface resistance of the support and the chargeability of the heat-sensitive recording material are shown in Table 2.

Example 4 A support was obtained by vapor-depositing aluminum on both sides of a polypropylene film with a thickness of 504 m to a surface resistance of approximately 2Ω. The heat-sensitive coating liquid of Example 1 was solidified on one side of this support. The coating was coated and dried for about 722 minutes to obtain a heat-sensitive recording material. The surface resistance value of the support and the chargeability of the heat-sensitive recording material are shown in the table below.

Comparative Example 1 The synthetic paper used in Example 1 at ℃ was used as a support without applying the conductive treatment liquid, and 1 tfl of the sensitive νL coating liquid of Example 1 was applied to about 7
? /rr? The coating was applied and dried to obtain a heat-sensitive recording material. Table 1 shows the surface resistance value of the support and the chargeability of the heat-sensitive recording material.

Comparative Examples 2 and 3 The conductive treatment liquid used in Example was applied to one side of the polyethylene terephthalate film used in Example 2 at a solid content of approximately 72%.
．． It was coated so as to form the arm and dried to obtain a support. The heat-sensitive coating liquid of Example 1 was applied on the conductive layer 1* of this support, and the heat-sensitive coating liquid was dried and browned.
Comparative Example 3 was obtained by applying and drying the heat-sensitive coating liquid of Example 1 on the surface not in lj L, and the evaluation results are shown in Table 2.1.

Comparative Examples 4 and 5 The conductive treatment liquid used in Example 1 was applied to one side of the polyethylene terephthalate film that had been heated at ℃ in Example 2 at a solid content of about 7 f/rr? ', 1.5f/rr on the other side?
The coating was applied and dried to obtain a support.

The conductive treatment liquid for this support was 79/n? The coated heat-sensitive recording material was Comparative Example 4, and the conductive treatment liquid was 1.5 fl/rr?
A heat-sensitive recording material obtained by applying and drying the heat-sensitive coating liquid of Example 1 on the coated surface was designated as Comparative Example 5. The evaluation results are shown in Table J.

Fang 1 table The measurement method was as follows.

]) Surface resistance measurement method Example 4 used a strip chamber 4, and the others used a universal electrometer MM A7 and a resistance measurement box P-601. °C, 65
Measured at an applied voltage of 1 V in an atmosphere of CH R, H.

2) Charging property evaluation method using a static honest meter manufactured by Shishido Shokai ℃゛J4mm
A corona charge of 6 kV was applied from a distance of .degree.

3) Continuous printing is performed using a high-speed Sasanetsu printer using a paper-passing fixed head, and if the recording paper breaks into the main body or the recording paper rubs against each other due to static electricity, it will be marked as an "X" and will cause trouble. Those without were marked as ○.

In the above examples 1 to 4, the recording paper was charged.

In contrast, in the comparative example, there were problems in which the recording paper stuck to the main body or the recording papers were pushed into each other due to charging.

Patent applicant: Honshu Paper Co., Ltd.

Claims (1)

[Claims] A heat-sensitive recording material comprising a heat-sensitive color-forming layer containing a color-forming substance and a color-developing substance that develops color by reacting the color-forming substance with heat on at least one surface of a support, wherein the support is synthetic paper. or a synthetic resin film, and the surface resistance value of the surface of the support to which the heat-sensitive layer is coated is 65'%R at 20°C.
A heat-sensitive recording material having a surface resistance value of 5 x 10'Ω or less in an H atmosphere, and a surface resistance value of 1.X10'Ω or less on the surface not coated with a heat-sensitive layer.