JPS60174687A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent ground contamination from occurring due to adhesion of an alcohol and unnecessitate overcoat layers, by using a specified phenolic compound as a color developer. CONSTITUTION:A phenolic compound of the formula, wherein R is a 2-8C alkylene group having 1-5 ether bonds, used as a color developer is sparingly soluble in alcohols at normal temperature, is capable of sufficiently developing the color of a color forming dye, and can be easily synthesized from a corresponding dihalogenoether compound and a corresponding alkali p-hydroxbenzoate by thje usual method. A colorless or a light-colored color forming dye used in combination with the phenolic compound may be crystal violet latcone or the like. The ratio of the amount of the phenolic compound to the amount of the dye in the thermal color forming layer is about 1:1-5, and the thermal recording material is produced by applying a liquid for forming the thermal color forming layer to an appropriate base such as a paper, followed by drying. The thermal recording material thus obtained has excellent alcohol resistance at both ground parts and image parts, and ensures favorable image stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that has excellent color development and other recording suitability, and has good image stability.

[Prior art]

General heat-sensitive recording materials are coated on a support such as paper or film, and contain a colorless or light-colored dye such as a leuco dye as a color former, and a phenolic compound (particularly bisphenol A) as a color developer to make the color develop when heated. A coloring system consisting of an acidic substance such as an organic acid is further provided with a heat-sensitive coloring layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are dispersed. 45-140
No. 39, Japanese Unexamined Patent Publication No. 48-27736, etc., and has been widely put into practical use. This type of thermal recording sheet produces a colored image through an instantaneous chemical reaction between a coloring agent and a color developer during heating (a thermal printer or facsimile machine with a built-in thermal head is used for heating). because there is,
Compared to other recording materials, records can be obtained in a short time using relatively simple equipment without complicated processing such as development and fixing, there is less noise generation and environmental pollution, and the cost is low. Due to the advantages of
It is useful as a recording material for various information and measuring instruments such as medical measuring instruments. However, as mentioned above, when heat-sensitive recording materials are made of a combination of colorless or light-colored dyes and acidic substances, if alcohol such as alcohol adheres to the skin (heat-sensitive recording materials for train tickets and medical measuring instruments). (Alcohol may adhere to the recording material), which has a major disadvantage in that the image area and the background area cannot be distinguished from each other and the recording material loses its value. This phenomenon is thought to be due to the fact that one or both of a color-forming dye, an acidic substance, especially a phenolic compound, is dissolved in alcohol, and this dissolved component causes a color-forming reaction after the alcohol evaporates. However, color-forming dyes generally used in heat-sensitive recording materials have very low solubility in alcohol at room temperature. In contrast, phenolic compounds, such as bisphenol A, have a very high solubility. From this, it is considered that the above phenomenon is substantially caused by the dissolution of the phenolic compound in alcohol.

Therefore, if a phenolic substance with low solubility in alcohol is used, it can be expected to be effective in preventing scalp contamination due to adhesion of alcohol. Furthermore, from another point of view, a heat-sensitive recording material in which an alcohol-resistant polymer overcoat layer is provided on a heat-sensitive coloring layer has been proposed as a heat-sensitive recording material that can be expected to have a similar stain prevention effect.In this case, it is necessary to provide an overcoat layer. This impedes heat conduction, lowering thermal sensitivity and increasing costs.

〔the purpose〕

The purpose of the present invention is to prevent skin contamination due to alcohol adhesion by using a phenolic compound that has very low solubility in alcohol at room temperature and has sufficient ability to develop color from colorless or light-colored dyes. An object of the present invention is to provide a heat-sensitive recording material that does not require an overcoat layer that reduces heat sensitivity.

〔composition〕

That is, the heat-sensitive recording material of the present invention uses, as a color developer, the general formula:
- is an alkylene group of ~8. ) It is characterized by using a phenolic compound shown in the following.

The present invention is based on the discovery that the phenolic compound of the above general formula is hardly soluble in alcohol at room temperature, and has the ability to sufficiently develop color with ordinary color-forming dyes.
It has been achieved.

Specific examples of the phenolic compound having the above general formula used in the present invention include the following.

4-H3 2H5 Note that these phenolic compounds can be easily synthesized by a conventional method using the corresponding dihalogenoether compound and an alkali salt of p-hydroxybenzoic acid as raw materials.

The colorless or light-colored color-forming dye used in combination with the above-mentioned phenolic compound may be any conventionally known dye, including the following.

Crystal violet lactone 3-diethylamino-6-methyl-7-anilinofluorane 3-(N-ethyl-P-toluidino)-6-methyl-7
-anilinofluorane 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran 3-pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-ani Linofluorane 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-anilinofluoran 3-diethylamino-7-(0-chloroanilino)fluoran 3-diethylamino-7-(m-trifluoromethylanilino)fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3 -Diethylamino-6-methylfluoran 3-Cyclohexylamino-6-chlorofluoran Here, the ratio of the phenolic compound to the coloring dye in the heat-sensitive coloring layer is preferably about 1:1 to 5 (by weight). .

In addition, in the heat-sensitive coloring layer of the present invention, various conventional binders may be used as appropriate for bonding and supporting on the support. For example, polyvinyl alcohol, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl Water-soluble materials such as pyrrolidone, polyacrylamide, polyacrylic acid, starch, and gelatin, or water-based emulsion type materials such as polystyrene, vinyl chloride-vinyl acetate copolymer, and polybutyl methacrylate can be used as the binder.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of recording material, such as fillers, surfactants, thermofusible substances, etc. (or lubricant) etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-formalin resin, starch, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of thermofusible substances include taki-grade fatty acids or their esters, amides, or In addition to metal salts, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermoplastics. 5 of fusible organic compounds, etc.
Examples include those having a melting point of about 0 to 200°C.

The heat-sensitive recording material of the present invention is produced by coating a heat-sensitive coloring layer forming liquid containing the above-mentioned components on a suitable support such as paper, synthetic paper, or plastic film, and drying it. Nisu 8 - Used as an excellent heat-sensitive recording material.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Note that both parts and percentages are based on weight.

Example 1 A mixture of the following formulations was pulverized and dispersed in a magnetic ball mill for 2 days to prepare liquids A, B, and C.

(A) Liquid formulation 3-(N-cyclohexyl-N-methyl 20 parts Amino)-6-methyl-7-anilinofluoran Hydroxyethyl cellulose 10% 20 parts Aqueous solution 60 parts"! 11 Liangxiao 3-Oxapentane-Bis-Lucht 20 parts Oxybenzoate (compound Nα2, melting point 135-136°C) 10% of hydroxyethyl cellulose 20 parts Aqueous solution 60 parts αλ11E-made calcium carbonate 20 parts Methyl cellulose Next, 10 parts of solution A, 30 parts of solution B, 30 parts of solution C, and 10 parts of a 20% alkaline aqueous solution of isobutylene-maleic anhydride copolymer were mixed to form a thermosensitive coloring layer forming solution. and this is the basis weight 5
After coating and drying on 0 g/m high-quality paper so that the dry coating amount was 45 g/Tr1' to form a heat-sensitive coloring layer, the layer surface was further calendered so that the surface smoothness was 500 to 600 seconds. A thermosensitive recording material (a) was prepared.

Example 2 Thermal recording material (b) was prepared in the same manner as in Example 1 except that the following liquid (D) was used instead of the liquid CB) in Example 1.
It was created.

(20 parts of 3.5-dioxahebutamethylene bis-p-hydroxybenzoate (compound No. 5, melting point 138-139°C)) 10% of hydroxyethyl cellulose 20 parts Aqueous solution 60 parts Comparative Example 1 Example A heat-sensitive recording material (C) was prepared in the same manner as in Example except that liquid (E) having the following formulation was used instead of liquid (B) in Example 1.

[E] Liquid formulation Bisphenol A 20 parts 10% of hydroxyethylcellulose 20 parts Aqueous solution 60 parts Comparative Example 2 Same as Example except that liquid [F] of the following formulation was used instead of liquid (B) of Example 1. A thermosensitive recording material (d) was prepared by the method.

(F) Liquid formulation P-Hydroxybenzoic acid benzyl varnish 20 parts 10% of 11-ethyl hydroxyethyl cellulose 20 parts Water solution 60 parts Next, each of the above heat-sensitive recording sheets was contacted at a pressure of 2 kg using a commercially available thermal gradient tester. Printing was performed at a time of 1 second and a temperature of 150'C. Ethyl alcohol was applied thinly to the image area and the background area of each of the obtained recordings by contacting absorbent cotton soaked with ethyl alcohol. The density of the image area and background area after ethyl alcohol evaporated was measured using a Macbeth densitometer and compared with that before ethyl alcohol was applied. The results are shown in the table below.

Table [Effects] As is clear from this table, the heat-sensitive recording material 12- of the present invention has excellent alcohol resistance in both the background area and the image area, and has good image stability.

Patent Applicant Ricoh Co., Ltd. - Representative Patent Attorney Toshiaki Ikeura Proceedings Amendment Written March 19, 1981 Commissioner of the Japan Patent Office Kazuo Wakasugi 51. 1. Indication of the case Patent Application No. 30927 of 1982 2. Name of the invention Heat-sensitive recording material 3. Relationship with the person making the amendment Patent applicant address 1-3-6 Nakamagome, Ota-ku, Tokyo Name (
674) Rico Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo Date of amendment order Voluntary 6 Number of inventions increased by amendment 0 7. Subject of amendment Column 8, Detailed explanation of the invention in the specification, Contents of amendment The following amendments will be made b1 in the specification of the application.

(1) Correct "1-5" on the last line of page 4 to "1-5".

(2) On page 9, line 10, "waterfall grade fatty acids" will be corrected to "higher fatty acids."

(3) “Oxapentane” in the 4th line from the bottom of page 10,
Corrected to "oxapentamethylene".

(4) “Method” in line 8 of page 12 will be corrected to “method.”

Claims (1)

[Claims] (1) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, the color developer has a general formula, (wherein R is 2 carbon atoms containing 1 to 5 ether bonds)
~8 alkylene group. ) A heat-sensitive recording material characterized by using a phenolic compound represented by: