JPS595093A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a high color concentration without heat escaping from a heat-sensitive head to a supporter by providing a layer composed primarily of fine hollow spherical granules between the supporter and the heat-sensitive coloring layer in a heat-sensitive recording material. CONSTITUTION:Fine hollow spherical granules (e.g., thermally expanded fine spheres, fine hollow glass powder, or fine hollow aluminosilicate powder) of a grain size of 10mum or less are dispersed in a binder (e.g., starch, casein, polyvinyl acetate, etc.) with water. The dispersion is coated on a supporter and dried to form an under layer, and then a heat-sensitive chromogenic substance and a binder are dissolved or dispersed in water to form a heat-sensitive coloring layer. As the heat-sensitive chromogenic substance, a composition composed of a combination of a compound with binary alcoholic hydroxyl groups, having a melting point of 100-180 deg.C, sulfur, and an inorganic salt or acetate of a metal may be cited preferably.

Description

[Detailed description of the invention] The present invention relates to heat-sensitive recording materials.

2. Description of the Related Art Heat-sensitive recording materials that are non-impact, have a fast recording speed, and are inexpensive are widely used as copy paper and for thermal printers of output devices of electronic computers.

This heat-sensitive recording material is generally formed by providing a single-layer or multi-layer heat-sensitive coloring layer containing a binder or a heat-coloring substance as a main component on a support such as paper or a plastic film.

It is important for heat-sensitive recording materials to effectively utilize minute heat obtained from a heat-sensitive head to obtain high color development (printing) of 8 degrees. Conventionally, for this purpose, improvements or selections have mainly been made to the binder, thermochromic substance, and additives of the thermosensitive coloring layer.

In response, the present inventors aimed to obtain a heat-sensitive recording material that can improve printing density even when using any of the known heat-sensitive color forming layer components. The present invention was completed after repeated studies, focusing on the fact that keeping the heat-sensitive layer in the heat-sensitive layer without escaping leads to improved print density.

That is, the present invention provides a heat-sensitive recording material having a heat-sensitive coloring layer on a support, in which a layer containing micro hollow spherical particles as a main component (hereinafter referred to as an "under layer") is provided between the support and the heat-sensitive coloring layer. It is characterized by:

The underlayer is provided to prevent heat from escaping from the heat-sensitive layer, and is designed to reduce the thermal conductivity of the layer as much as possible. That is, the micro hollow particles have low thermal conductivity (approximately 0.20 W/m or less).
In addition, hollow microparticles are used to further lower the thermal conductivity of the entire tC under.

Specific examples of micro hollow spherical particles used here include the following.

1) Expanded thermally expandable microspheres Hollow particles with a capsule wall made of thermoplastic material, containing a volatile expanding agent inside the core particle Thermoplastic material: Vinylidene chloride-acrylonitrile copolymer etc.

Volatile swelling agents 20-butane, isobutane.

neopentane petroleum ether Le et al.

Thermal conductivity = 0.02 to 0.06 w/m ・Example: Micronol 9-L manufactured by Matsumoto Yushi Co., Ltd., Bxp manufactured by Kemanord Co., Ltd.
ameal 2) Glass micro-hollow sphere powder borosinate glass microspheres Thermal conductivity == 0.11 W/m-Example: Gura, 6-Bell Company! I! ! Microca1M3
) Aluminosilicate micro hollow sphere powder for low foaming injection molding and standard injection mold Zolemix thermal conductivity = 0.07 W/m- Example: Nippon Fillite Co., Ltd. HFill IC The above micro hollow sphere particles have a particle size of 5 μm 1 to 200 μm. There is a range of about 100mm, but if you want to use the underlayer, it is recommended to select and use one with a diameter of 10IIm or less.

The thermochromic substance used in the present invention is found in many literatures related to thermosensitive copying paper and recording paper, but compositions consisting of the following combinations of components are preferred.

(,) A melting point of 100~ having a secondary alcoholic hydroxyl group, which is described in Japanese Patent Publication No. 41-14510.
A composition of a combination of a 180° C. compound, sulfur and metal inorganic salts or metal vinegar M salts.

Examples of compounds having a secondary alcoholic hydroxyl group include benzoin compounds such as benzoin, 2-methoxybenzoin, 4-chlorobenzoin, 4-dimethylaminobenzoin, 2-10-4'-dimethylaminobenzoin, and diphenylcarbinol. Carbinols such as resorcinol, pyrogallol, 3-hydroxytoluene-4-sulfonic acid, 4-nitroresorcinol, 4.
phenolic compounds such as 6-dibromoresorcin;
Examples include fatty acid polyhydric alcohols such as erythritol, sorbitol, galactose, maltose, mannitol, and saccharose. Inorganic metal salts and acetates of metals include a number of metals that react with hydrogen sulfide to form colored sulfides, such as copper, lead,
These include tin, molybdenum, conort, chromium, nickel, manganese, titanium, antimony, rhodium, osmium, mercury, iron, barium, bismuth, arsenic, magnesium, indium, and iridium.

(b) Comprised of a thermochromic compound described in % Publication No. 14511/1983, which is a combination in which the various inorganic metal salts 5- in the composition of a above are replaced with hexamethylenetetramine/metal salt adducts. Composition.

(c) A composition comprising a combination of a carbohydrate and a dehydrating agent, as described in Japanese Patent Publication No. 42-132!117.

Here, carbohydrates include saccharose, fructose,
Examples include galactose, starch, etc. - Examples of strong water agents include sulfuric acid, acetic anhydride, anhydrous zinc chloride, and sodium p-toluenesulfonate.

In addition to the above-mentioned compositions, a number of combinations of compounds such as those described below are known as compositions made of compounds that develop color upon heating.

(a) Combinations of long-chain fatty acid iron salts such as ferric stearate and ferric myristate and phenols such as tannic acid, gallic acid, and ammonium salicylate.

(B) Heavy metal salts of organic acids such as nickel, coronate, lead, copper, iron, mercury, and silver 6-salts such as acetic acid, stearic acid, and palmitic acid, and alkalis such as calcium sulfide, strontium sulfide, and norium sulfide. A combination with an earth metal sulfide, or a combination with the organic acid heavy metal base and 8-
Combination with organic chelating agents such as diphenylcarnocyto and diphenylcarnocin.

e→ Heavy metals such as silver, lead, mercury, and thorium oxalate J
f% oxalate in combination with sulfur compounds such as Na-tetrathionate, sodium thiosulfate, thiourea.

) Fatty acid ferric salts such as ferric stearate and 3
．． Combination with aromatic polyhydroxy compounds such as 4-dihydroxytetraphenylmethane.

(e) A combination of an organic acid noble metal salt such as oxalic acid or mercury with an organic polyhydroxy compound such as polyhydroxy alcohol, glycerin, or glycol.

(f) Combinations of noble metal salts of organic acids such as silver behenate and silver stearate with aromatic organic reducing agents such as protocatechuic acid, spiroindane, and hydroquinone.

(g) A combination of a fatty acid ferric salt such as ferric pelargonic acid or ferric laurate and a thiosemicarnosite or thiosemical Jsite derivative.

(g) Combinations of organic acid lead salts such as caproate, pelargonate, lead behenate and thiourea derivatives such as ethylenethiourea and N-dodecylthiourea.

(S) A combination of a heavy metal salt of a higher monofatty acid such as ferric stearate or copper stearate and zinc dialkyldithiocarnomate.

Closed) Those that form oxazine dyes, such as the combination of resorcinol and nitroso compounds, or those that form azo dyes.

Q→ Crystal Novel A colored dye is formed by heating using colorless dyes such as lactones such as iolet lactone, spiropyrans, and fluoranes, and bisphenol A1 and other phenols and organic acids.

(4) A diazonium salt and a coupler that form a diazo dye (diazo-based heat-sensitive layer).

However, the present invention is not limited to such a combination of thermochromic compositions, and any thermochromic material that develops color with heat, which is used in the field of thermal copying, can be applied.

In addition, known binder resins can be used for the underlayer and the heat-sensitive layer, such as starch, casein, polyvinyl acetate, polyvinyl alcohol, ethylene-acrylic acid alkali salt copolymer, styrene-citadiene. These include copolymers, ethylene-♂yl acetate copolymers, styrene-maleic acid copolymers, acrylic ester resins, acrylic ester-vinyl acetate copolymers, and the like.

In order to produce the thermosensitive recording material according to the present invention, micro hollow spherical particles are dispersed in a binder and water, and this is coated and dried on a support to form an underlayer. A heat-sensitive coloring layer may be provided by dissolving or dispersing the same in water.

Hereinafter, the effects of the present invention will be clarified through Examples.

Example 1 [Liquid A] Thermally expandable microspheres (Matsumoto Yushi Co., Ltd. Micropearl P-30
)ISfi parts PVKIO water solution 50 parts by weight water
45 parts by weight of the above composition was dispersed using a homomixer to prepare [Liquid A].

[Liquid B]

00,H.

Stearic acid amide 7 layers Salt pea vinyl acetate copolymer 5 layers 1 part Methyl cellosolve 877 layers The above composition was dispersed in a ball mill to prepare [Liquid B].

10- [0 liquid] Naphthol As 2 parts by weight 4-benzoylamino-2,5-jethoxy-acetoacetanilide 3 parts by weight N-sudearylbenzamide 10 parts by weight Imidazole sxi part Silica 5 parts by weight Inbutylene-maleic anhydride copolymer Combined 5 parts by weight water
70 parts by weight of the above composition was dispersed in a ball mill to prepare [Liquid C].

Undercoat 50 f/- high-quality paper with [reduced number of people] so that the dry electricity amount is 2φ-. xto'clj 1 in the air
The thermally expandable microspheres were allowed to expand for a minute. A on top of that
The liquid was coated and dried in a drying chamber so that the drying weight was 1 It and 2.5 t/-, and furthermore, liquid B was coated and dried so that the dry weight was 20 v/- to obtain thermosensitive recording paper.

Example 2 Glass micro hollow sphere powder (Mlcroca 1M manufactured by Plano 9-Bell) was used instead of the thermally expandable microspheres in Example 1.
A thermal paper was obtained in the same manner except that %.

Example 3 In Example 1, aluminosilicate micro hollow sphere particles (Fil1 manufactured by Nippon Philite Co., Ltd.) were used instead of the heat-formable microspheres.
A thermal paper was obtained in the same manner except that 1te) was used.

Example 4 [Liquid D] Crystal noseiolet lactone 10:i
ii part Stearic acid amide 15 parts by weight Silica f4. It part PVA 10% water bath liquid 10 parts water 6OJl
Part ii The above composition was dispersed in a ball mill to prepare [Liquid D].

[Liquid B]

Bisphenol A 20 parts PVAl 0% aqueous solution 2 Otp parts Water 60 parts The above composition was dispersed in a ball mill to prepare [Liquid E].

[F liquid]

Thermally expandable microspheres (Micropearl p-8o manufactured by Matsumoto Yushi Co., Ltd.)
s parts by weight Salt-pea-vinegar-picopolymer emulsion (50%) 10
Part by weight water 85
Part by Weight The above composition was dispersed in a ball mill to prepare [Liquid F].

Undercoat 50 f/- high-quality paper with [Liquid F] to a dry weight of 2-snow. The thermoplastic spherules were expanded by leaving them in a 110'C atmosphere for 1 minute. On top of that [D
A 1:1 mixture of [Liquid] and [Liquid E] is placed in the drying room f9.
The coating was applied and dried to obtain a heat-sensitive recording paper.

Example 5 In Example 4, instead of thermally expandable microspheres, glass micro hollow sphere powder (Mlcrocsl M manufactured by Grano-Pell Co., Ltd.
Thermal paper 13- was obtained by filtration using the same method aII except that ) was used.

Example 6 In Example 4, aluminosilicate micro hollow spheres (Nippon Philite Co., Ltd.'!RFil) were used instead of thermally expandable microspheres.
A thermal paper was obtained in the same manner except that llt.) was used.

Comparative Example For comparison, the thermally expandable microspheres in the undercoat liquid in Example 1.4 were replaced with solid caco (thermal conductivity: 2 to 3).
Thermal paper was obtained in the same manner except that the paper was replaced with W/m-K) and designated as Comparative Example 11 and Comparative Example 2, respectively.

When the heat-sensitive recording paper obtained as described above was printed using a facsimile machine IFAX 3300, color developed, and when measured with a Macbeth # dial, the density was as shown in the table below.

14- It can be seen that when micro hollow spherical particles are used for under-concentration, the direction of concentration is remarkable.

15- 519-

Claims (1)

[Claims] L. A heat-sensitive recording material having a heat-sensitive color forming layer on a support, characterized in that a layer containing micro hollow spherical particles as a main component is provided between the support and the heat-sensitive color forming layer.