JPH029683A - Thermal recording sheet - Google Patents

Abstract

PURPOSE:To perform writing having sharp hue using oily ink by incorporating not only a compound represented by a specific formula as a coupler but also 4-biphenyl p-tollyl ether or dibenzyl oxalate in a thermal color forming layer. CONSTITUTION:A compound represented by formula I (wherein R is a 1-3 alkyl group) is used as a coupler. There is no special limit as a basic leuco dye to be used but a triphenylmethane compound, an azaphthalide compound and a fluorene compound are pref. Other than the coupler and the dye, 4-biphenyl p-tollyl ether or dibenzyl oxalate is used as a sensitizer. The use amounts of these components per 1pts. of the basic leuco dye are usually set so that the org. coupler is 1-8pts., the sensitizer is 3-10pts. and a filler being other component is 1-20pts. and a binder is properly used in an amount of 10-25% by wt. of the total solid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a highly sensitive heat-sensitive recording sheet with improved writing properties using oil-based ink.

(Prior art) In general, heat-sensitive recording sheets are produced by grinding and dispersing a colorless or light-colored basic colorless dye and an organic color developer such as a phenolic substance into fine particles, and then mixing them together, filling them with a binder, etc. agent, sensitivity enhancer.

A coating liquid obtained by adding lubricants and other auxiliary agents is applied to a support such as paper, synthetic paper, film, or plastic. Color recording is obtained through a chemical reaction.

These heat-sensitive recording sheets can be used in a total of 11 recorders, convenience store terminals, printers, and facsimiles.

It is applied to a wide range of fields such as automatic ticket vending machines and barcode labels, but these recording devices are diversifying.

As performance increases, the quality required for heat-sensitive recording sheets also becomes more advanced.0For example,
As recording speeds increase, it is required to obtain clear colored images with high density even with minute thermal energy, and on the other hand, heat-sensitive recording sheets with excellent preservability such as light resistance, weather resistance, and oil resistance are required. ing.

On the other hand, bis(hydroxyphenyl) vinegar m Thermal responsiveness using
Heat-sensitive recording materials have been proposed that have excellent weather resistance, smoothness, water resistance, oil resistance, plasticizer resistance, and the like.

(Problems to be Solved by the Invention) However, the thermal responsiveness of these thermosensitive recording materials is still not satisfactory.

Furthermore, as thermal recording paper has recently become popular, there are more opportunities to add notes using oil-based felt-tip pens after thermal recording. However, since oil-based inks contain various organic solvents, for example, when writing on black color-forming thermal recording paper using oil-based ink, the original black color of the thermal recording paper, which is the coloring caused by the solvent, will be lost. A problem arises in that pure red writing cannot be obtained because the coloring and the red color of a similar ink are mixed. This applies not only to red but also to other colors.

An object of the present invention is to solve these problems and provide a highly sensitive heat-sensitive recording sheet on which writing can be done in clear colors using felt-tip pens with oil-based ink of any color.

(Means for Solving the Problems) The present invention uses the following general formula (
Using the compound represented by 1) and 4-biphenyl P
- By containing tolyl ether or oxalic acid dibenzyl ester, the above problems are solved at once.

OOR [wherein R represents an alkyl group having 1 to 3 carbon atoms, J] Specific examples of the compound represented by the general formula (1) include the following.

Methyl bis(4-hydroxyphenyl)acetate
Hydroxyphenyl) ethyl acetate bis(4-hydroxyphenyl) n-propyl bis(4-hydroxyphenyl) isopropyl acetate The basic colorless dye used in the present invention is particularly III
Although not subject to WE, preferred are triphenylmethane type, fluorane type, azatuclide type, fluorene type, etc., and specific examples thereof are shown below.

Triphenylmethane leuco dye 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalidonofluorane 3-(N-ethyl-p-tolubuino)-6-methyl-
7-anilinofluoran 3-(N-ethyl-N-ynamylamino)-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7-(o,p dimethylanilino)fluoran 3 -pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-anilinofluoran 3-diethylamino-7-(m-trifluoromethylanilino)fluoran 3-N-n-dibutylamino-6-methyl-7-anilinofluoran 3-N-n-dibutyl Amino-7-(O-chloroanilino)fluoran 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7-(a, p -dimethylanilino)fluoran 3-(N-methyl-N-protoruamino)-6-methyl-7-ayurifluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-dibutylamino-7 -(o-Chloranilino)fluoran 3-diethylamino-7-(o-chloroanilino)fluoran 3-diethylamino-6-methyl-chlorofluoran 3-diethylamino-6-methyl-fluoran 3-cyclohexylamino-6-chlorofluoran 3-diethylamino-benzo[a]-fluorane azaphthalide, leuco 8 3-(4-diethylamino-2-ethoxyphenyl)-
3-(1-ethyl-2-methylindol-3-yl)
-4-Azaphthalide 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-7-azaphthalide 3-(4-diethylamino-2-ethoxyphenyl) - 3-(1-cutyl-2-methylindol-3-yl)-4-azaphthalide 3-(4-N-cyclohexyl-N-methylamino-
2-methoxyphenyl) -3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide fluorene 1, leuco dyed 3, 6.6°-tris(dimethylamino)spiro[fluorene- 9,3°-phthalide] 3.6.6'-tris(diethylamino)spiro[fluorene-9,3°-phthalide] These dyes can be used alone or in combination of two or more.

In the present invention, 4-biphenyl p-tolyl ether or dibenzyl oxalate is used in addition to the above color developer and dye. These have functions as sensitizers, but
This is extremely effective for the purpose of the present invention.

In the present invention, as an image stabilizer.

4.4°-Butylidene (6-t-butyl-3-methylphenol) 2.2°-di-t-butyl-5,5′-dimethyl-4,
4-Sulfonyldiphenol 1.1. :l-tris(2-methyl-4-hydroxy-
5-cyclohexylphenyl)butane 1.1.3-tris(2-methyl-4-hydroxy-5-butylphenyl)butane, etc. can also be added.

The binder used in the present invention has a polymerization degree of 200
-1900 fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, other modified polyvinyl alcohols,
Hydroxyethylcellulose, methylcellulose dicarboxymethylcellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethylcellulose, acetylcellulose, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, Examples include polyvinyl butyral polystyrene and copolymers thereof, polyamide resins, silicone resins, terpene resins, ketone resins, and coumaron resins.

The amount of organic color developer and basic colorless dye used in the present invention,
The types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited.5 Usually, 1 to 8 parts of organic color developer to 1 part of basic colorless dye. , 3 to 10 parts of sensitizer and 1 to 20 parts of filler are used, and the binder is suitably in an amount of 10 to 25% of the total solid content.

A desired heat-sensitive recording sheet can be obtained by applying a coating liquid having the above composition to any support such as Paper 1 synthetic paper, film, or plastic.

The above-mentioned #1 color developer, basic colorless dye, sensitizer, and materials to be added as necessary are finely pulverized to a particle size of several microns or less using a grinder such as an attritor sand grinder or a suitable emulsifier. The coating liquid is prepared by adding a binder and various additive materials depending on the purpose.

This coating liquid includes fillers, mold release agents to prevent sticking such as fatty acid metal salts, lubricants to prevent pressure coloring such as fatty acid amide, ethylene bisamide, Monkun wax, and polyethylene wax, sodium dioctyl sulfosuccinate, Addition of dispersants such as sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, alginate, etc., benzophenone-based or triazole-based ultraviolet absorbers, other antifoaming agents, optical brighteners, waterproofing agents, etc. I can do it.

As fillers used in the present invention, all inorganic and organic fillers commonly used in the field of paper processing can be used, such as clay, talc, silica, magnesium carbonate, alumina, aluminum hydroxide, Magnesium, barium sulfate, kaolin, titanium oxide, zinc oxide, calcium carbonate, aluminum oxide, urea, formalin resin.

Examples include fine particles of polystyrene, phenol resin, and the like.

Furthermore, for the purpose of increasing color development sensitivity, an undercoat layer such as a polymer material containing filler may be provided under the heat-sensitive layer.

(Function) The reason why the heat-sensitive recording sheet of the present invention does not change color even when written with oil-based ink is considered to be as follows. Generally, when writing is performed on a heat-sensitive recording sheet with a felt-tip pen using oil-based ink, the color developer, leuco dye, and sensitizer in the heat-sensitive coloring layer are dissolved in the organic solvent contained in the ink.

Then, as the solvent evaporates, a coloring composition in which these color developer, leuco dye, and sensitizer are integrated is formed on the writing area. Therefore, for example, when red ink is used, the red color and the developed color of the heat-sensitive recording sheet are mixed, resulting in a dull written image.

On the other hand, the heat-sensitive recording sheet of the present invention uses a specific color developer bis(
It consists of 4-hydroxyphenyl)acetate, a leuco dye, and a specific sensitizer. Furthermore, the solubility of these materials in solvents is extremely low, and almost no color-forming composition is formed even when the solvent evaporates, so it is thought that discoloration due to oil-based ink does not occur.

Furthermore, in the present invention, the melting/dissolving diffusion rate and saturation solubility of the color developer with respect to the sensitizer used are extremely high, and the melting/dissolving diffusion rate and saturation solubility of the dye are also high. When a coloring agent, a sensitizer, and a leuco dye cause a physicochemical reaction, a coloring composition is quickly formed, and a colored image with high density can be obtained.

Furthermore, the sensitizer used in the present invention has a property that crystallization is extremely difficult to occur even when dissolved in the organic solvent contained in the oil-based marker and the subsequent vaporization of the solvent, so it can be written with oil-based ink. No white powder is produced when

(Example) The present invention will be explained below using examples. In addition, during explanation 1
Parts indicate parts by weight.

[Example (Test No. 1 to 2)] Solution A (developer dispersion) Solution B (dye dispersion) Cti (sensitizer dispersion) The above composition was ground with a sand grinder. A large amount of the composition is ground to an average particle size of 1 using a sand grinder.
The particles were ground to a micron diameter and then ground to an average particle size of 1 micron as shown below. Next, the dispersion liquid was mixed in the following proportions to prepare a coating liquid. A coating liquid was prepared by mixing the dispersion liquid in the following proportions.

50g of each of the above coating liquids was applied on one side of the base paper, 6.0g.
/r*'' and dried, and the sheet was treated with a supercalender to give a smoothness of 200 to 600 seconds to prepare a heat-sensitive recording sheet.

[Comparative Example 1 (Test Nos. 3 to 6)] Liquid E (Developer Dispersion) A heat-sensitive recording sheet was prepared in the same manner as in Example 1.

[Comparative Example 2 (Test No. 7 to 12)] Solution A (Developer Dispersion) Solution B (Dye Dispersion) Solution B (Dye Dispersion) Solution F (Sensitizer Dispersion) Of the above compositions The multiliquid was ground to an average particle diameter of 1 micron using a sand grinder, and then a dispersion liquid was mixed in the proportions shown below to prepare a coating liquid.

Thereafter, a heat-sensitive recording sheet was prepared in the same manner as in Example 1.

Table 1 summarizes the results of quality tests performed on the thermal recording papers obtained in the above Examples and Comparative Examples.

Sho (1) Note (2) Sho (3) Sho (4) Static color density: 10 g7c on a hot plate heated to 105℃
Press for 5 seconds at a pressure of m2 and color develops, which is measured using a Macbeth densitometer (RO-914, using an amber filter. The same applies hereinafter).

Dynamic color density: Matsushita Densen - Thermal facsimile UF-1
000, applied energy 0.58mj/Dot
, the image density recorded with a pulse width of 0.97 milliseconds was measured using a Macbeth densitometer.

Discoloration due to oil-based ink;! ? Using Nishi Kagaku oil-based red magic ink No. 500! It was written on a thermal paper sample, and the degree of discoloration compared to the original red color was visually checked.

O...Almost no discoloration △...Slight discoloration ×...White powder caused by oil-based ink that changes color in the heat: Written on a thermal paper sample using Teranishi Chemical oil-based red magic ink No. 500 After 15 minutes, the degree of white powder generation was visually measured.

0...-No white powder is produced. ×−・− White powder occurs (Effect of the invention) The following points can be mentioned as effects of the present invention.

When writing with felt-tip pens using oil-based ink, there is no discoloration or generation of white powder, making it possible to freely write on heat-sensitive recording sheets using these writing instruments.

(2) Excellent thermal response.

Procedure amendment writing method) August 4, 1986 1.7 Commissioner of the Office Kichi II Bunki 1986 s
Date of submission 1, 'iT' Indication of Patent Application No. 161871 of 1988 2, Name of the invention Heat-sensitive recording material 3, Relationship with the case of the person making the amendment Patent applicant's address and name 114 Oji, Kita-ku, Tokyo IT Item No. 4 No. 1 Jujo Paper Co., Ltd. 4, Agent 〒114 δ911 Spontaneous writing of procedural amendment) ■, Indication of case 2, Name of invention 1986 Patent Application No. 161871 Thermal Recording Sheet 3, Person making amendment Case Relationship with Patent applicant Address: 1-4-1 Oji, Kita-ku, Tokyo Name: Jujo Paper Co., Ltd. 4, Agent: 114 ff1911-51065,
Date of amendment order Vol. 5, date of amendment order Vol. 6, subject of amendment "Claims" column 7 of the specification, content of amendment (1) The claims are amended as shown in the attached sheet.

(2) The name of the invention is amended to “Thermal Recording Sheet 1.”

(3) "Various" on page 3, line 17 of the specification is corrected to "1" for r-butanol, toluene, xylene, ethyl acetate, etc.

(4) Change “to an organic solvent” on page 12, line 16 of the specification to r
Correct 1 for volatile organic solvents.

(5) “Magic” on page 13, lines 18-19 of the specification
is corrected as r ink 1.

Scope of Claims (1) A thermosensitive recording sheet in which a thermosensitive coloring layer containing a colorless or light-colored basic colorless dye and an organic color developer as main components is provided on a support, wherein the thermosensitive coloring layer has a Contains a compound represented by the following formula (I) as a color developer,
A heat-sensitive recording sheet characterized by containing 4- and phenyl p-tolyl ether or oxalic acid dibenzyl ester.

OOR [In the formula, R represents an alkyl group having 1 to 3 carbon atoms. ]

Claims (1)

[Claims] (1) In a heat-sensitive recording sheet in which a heat-sensitive color-forming layer containing a colorless or light-colored basic colorless dye and an organic color developer as main components is provided on a support, the heat-sensitive color-forming layer has the following organic color developer: 1. A heat-sensitive recording sheet which prevents discoloration caused by an oil-based marker and is characterized by containing a compound represented by the general formula (I) and 4-biphenyl p-tolyl ether or oxalic acid dibenzyl ester. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) [In the formula, R represents an alkyl group having 1 to 3 carbon atoms. ]