JPH03176191A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having high sensitivity and excellent in storage stability by containing 1, 2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide in a color forming layer. CONSTITUTION:In a color forming layer containing a colorless-light-colored color forming substance and the coupler developing the color of said substance at the time of heating, 1, 2-bis(3,4-dimethylphenyl)ethane represented by formula and a higher fatty acid amide compound are contained. In this case, both of them are simultaneously emulsified to be contained in the color forming layer. The higher fatty acid amide compound is 12 - 30C higher fatty acid amide and, for example, stearamide, 12-hydroxystearamide, N-hydroxymethylamide of higher fatty acid or N-hydroxymethylstearamide are designated. 1, 2-bis(3,4- dimethylphenyl)ethane has marked effect as a sensitizer and this effect can be markedly increased using the higher fatty acid amide compound.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat-sensitive recording material, and more particularly, 1,2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide type compound as a stimulant. By blending,
The present invention relates to a heat-sensitive recording material that achieves high sensitivity and has improved storage stability.

[Conventional technology and its problems]

A heat-sensitive recording material is a color-forming system consisting of a usually colorless or light-colored color-forming substance such as a leuco dye, a color developer that develops color when heated, and a sensitizer on a support such as paper, synthetic paper, or resin film. , a heat-sensitive coloring layer in which a binder and other additives are dispersed is provided, and when a heat-generating element such as a thermal knife or a hot pen comes into contact with this recording medium in a recording device, the dye and color developer react. The image is recorded as a color such as black.

Compared to other recording materials, heat-sensitive recording materials have advantages such as being able to record in a short time, generating less noise, and being inexpensive. It is widely used as a recording material for , telex, ticket vending machines, etc.

Conventionally, as colorless or light-colored color-forming substances, for example, leuco dyes having a lactone, lactam or spiropyran ring have been used, and as color developers, various acidic substances have been proposed, and in particular, phenolic compounds, such as , bisphenol A, p-hydroxybenzoic acid benzyl ester, etc. have been used singly or in combination, but when these phenols are used, it is difficult to achieve high speed and high density recording, and There was a drawback that color unevenness occurred.

Therefore, attempts have been made to achieve higher sensitivity by using a sensitizer, which is a third substance, as a color-forming substance or developer. For example, various waxes, dimethyl phthalate, stearamide, phenyl benzoate, terphenyl, bis(vinyloxyethoxybenzene, p-acetyloxybiphenyl, etc.) have been proposed.

However, these sensitizers are not effective unless used in large quantities, and do not fully satisfy the demand for high sensitivity of heat-sensitive recording materials.Furthermore, they cause fogging or discoloration during storage. It had the disadvantage of sipping, and was not practically satisfactory.

In addition, in Japanese Patent Publication No. 59-25674, melting point 60''
It has been proposed to use substituted biphenylalkanes with a temperature of C to 200°C as sensitizers, and it is stated that the use of these sensitizers improves the color development sensitivity compared to the case of using stearic acid amide. has been done. In the above publication, as specific examples of substituted biphenylalkanes,
1.2-bis(2,4-dimethylphenyl)ethane, 1
．． 2bis(2,4,5-trimethylphenyl)ethane and the like are mentioned as suitable compounds.

However, even when these substituted biphenylalkane compounds are used, they are not only insufficient for achieving high sensitivity for faster recording, but also have problems in terms of storage stability under harsh usage conditions. This was insufficient, and further improvements were strongly desired.

[Means for solving problems]

In view of the above-mentioned current situation, the present inventors have achieved high sensitivity and
As a result of extensive research to find a sensitizer with good storage stability, we found that among the substituted biphenyl alkane compounds used as sensitizers, there are no compounds specifically described in Japanese Patent Publication No. 59-25674. 2-bis(3,4-dimethylphenyl)ethane has a significantly greater effect as a sensitizer than other similar substituted biphenylalkane compounds, and this effect can be improved by using higher fatty acid amide compounds. We have found that it can be significantly increased.

In addition, the present inventors have found that the effect is even more pronounced when 1,2-bis(3,4 dimethylphenyl)ethane and a higher fatty acid amide compound are emulsified together. It has been found that the effect is even more pronounced when a highly purified higher fatty acid amide compound containing 90% by weight or more of a single higher fatty acid amide compound is used as the fatty acid amide compound.

The present invention has been made based on the above findings, and provides a heat-sensitive recording material provided with a color-forming layer containing a normally colorless or light-colored color-forming substance and a color developer that causes the rostrum to develop color when heated. The present invention provides a heat-sensitive recording material, characterized in that the coloring layer contains 1,2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide compound represented by the following formula. .

Although it is not clear why the combination of 1.2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide compound synergistically increases the sensitivity or significantly improves the storage stability. , 1.2-bis(3
, 4-dimethylphenyl) ethane and the higher fatty acid amide compound at the same time, the effect is further improved, so that due to some kind of inkling, both produce a low-energy coloring effect (increased sensitivity). It is presumed that storage stability is improved by preventing color development (prevention of fogging) at energy levels equivalent to storage conditions and by preventing volatilization of the sensitizer.

Hereinafter, the present invention having the above-mentioned summary will be explained in more detail.

Various dyes are well known as the usually colorless or light-colored color-forming substances used in the present invention, and there are no particular limitations as long as they are used in general pressure-sensitive recording paper, heat-sensitive recording paper, etc. .

Specific examples of these dyes include (1) triarylmethane compounds; for example, 3,3-bis(p dimethylaminophenyl)-6-dimethylaminophthalide (commonly known as crystal violet lactone), 3-(p -dimethylaminophenyl)-3(1,2-dimethyl-3-indolyl)phthalide, 3-(p-dimethylaminophenyl)
-3(2-phenyl-3-indolyl)phthalide, 3゜3-bis(9-ethyl-3-carbazolyl)-5dimethylaminophthalide, 3.3-bis(2phenyl-3-indolyl)-5- Dimethylaminophthalide, etc., (2) diphenylmethane compounds; for example, 4,4-bis(dimethylamino)benzhydrin benzyl ether, N-2
,4,5-)lichlorophenylleucoolamine etc., (
3) Xanthine compounds; for example, rhodamine-β-anilinolactam, 3-dimethylamino-7-medoxyfluoran, 3-dimethylamino-6-medoxyfluoran, 3-dimethylamino-7-lylorofluorane, 3-
Diethylamino-7-methoxyfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7 dimethylfluorane, 3-diethylamine-7methylaminofluorane, 3-diethylamino 7-octylamino Fluoran, 3-diethylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-6-chloro-7-r-chloropropylaminofluoran, 3-diethylamino-6-methyl-7-
Xylidinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6
-Chloro-7(β-ethoxyethylamino)fluoran, 3-diethylamino-7-(2-carbomethoxyphenylamino)fluoran, 3-diethylamino-7-ethylaminofluorane, 3-diethylamino-7-sibenzylaminofluoran , 3-diethylamino-7-(N
-acetyl-N-methylamino)fluoran, 3-diethylamino-7(N-methyl-N-chloroethylamino)fluoran, 3-diethylamino-7-(N-methylN-hensylamino)fluoran, 3-dibutylamino-6 -Methyl-7-anilinofluorane, 3 Dibutylamino-7-(2-chloroanilino)fluorane, 3-
Di-n-amylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-n-amylamino)-
6-Methyl-7anilinofluorane, 3-(N-methyl-N-nhexylamino)-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexylamino)-6 -Methyl-7-anilinofluorane, 3-C
N-ethyl-N-isopropylamino)-6-methyl-
7-anilinofluorane, 3(N-ethyl-N-n-amylamino)-6methyl-7-anilinofluorane, 1
-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-Nn-
hexylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-β-ethylhexylumino)-6-methyl-7-anilinofluorane, 3-(N
-ethyl-p-toluidino)-7-methylfluorane,
3-piperidino6-methyl-7-anilinofluorane,
3-(N-ethyl-p-toluidino)-6-methyl-=7
Anilinofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-(p-4luidino)fluorane, 3-pyrrolidino-6-methyl-7anilinofluorane, 3-pyrrolidino-6 -Methyl-7-p-butylphenylaminofluorane, etc., (4) Thiazine compounds; For example, benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc.; (5) Spiro compounds; For example, 3-methylsuvirodinaphtho. These dyes include pyran, 3-ethylspirogyrone, 3-benzylspirodinaphthopyran, 3-methylnat(3-methoxybenz)spiropyran, etc.
It is also possible to use a mixture of lffs.

Furthermore, the color developer used in the present invention includes, for example, p
-octylphenol, p-tert-butylphenol, ρ
Phenylphenol, p-hydroxyacetophenone, α-naphthol, β-naph[-l, ρ-tert-octylcatechol, 22゛-dihydroxybiphenyl, bisphenol A, I, l-bis(p-hydroxyalkyl)butane, 2.2-bis(4-hydroxyphenyl)
hebutane, 2,2-bis(3-methyl-4-human-1xyphenyl)propane, 2,2-bis).

5-dimethyl-4-hydroxyphenyl)propane, 2
2-bis(3,5-dichloro-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, bis(3,4-dihydroxyphenyl)sulfone, bis(3-allyl-4hydroxyfurnyl)sulfone , 4
-Hydroxy-4°-isopropoxydiphenyl sulfone, 1.1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)ether,
p-hydroxybenzoic acid, ethyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, butyl bis(4-hydroxyphenyl) acetate, l, ■.

3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, l, 1.3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, bis(2-(4 -Hydroxyphenylthio)ethoxy]methane, phenols such as 4-hydroxyphthalic acid dimethyl ester; aliphatic carboxylic acids such as oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearic acid, behenic acid; benzoic acid, Tertiary-butylbenzoic acid, phthalic acid, gallic acid, salicylic acid, isopropyl salicylic acid,
Phenylsalicylic acid, 3.5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 3.5-di(
α-Methylhensyl)salicylic acid, 3-phenyl-5-
Aromatic carboxylic acids such as (α, α-dimethylhensyl) salicylic acid and polyvalent metal salts of these aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel: acid clay, active White clay, Akpal guide, bentonite, colloidal silica,
Examples include inorganic color developers such as aluminum silicate, magnesium silicate, zinc silicate, tin silicate, calcined kaolin, and talc.

The higher fatty acid amide compound used in the present invention is an amide compound of higher fatty acid having 12 to 30 carbon atoms, such as higher fatty acid amide, N-alkyl or alkenyl higher fatty acid amide, N-hydroxyalkyl higher fatty acid amide, alkylene or Examples include arylenbis (higher fatty acid amide).

Specifically, lauric acid amide, myristic acid amide,
Palmitic acid amide, stearic acid amide, 12-hydroxystearic acid amide, oleic acid amide, ricinoleic acid amide, erucic acid amide, behenic acid amide, N-
Oleyl palmitic acid amide, N-stearyl stearic acid amide, N-oleyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl oleic acid amide, N-stearyl erucic acid amide, N-hydroxymethyl stearic acid amide, N- Hydroxyethylstearamide, N-hydroxymethylbehenic acid amide, methylene bis (stearic acid amide), ethylene bis (lauric acid amide), ethylene bis (myristic acid amide), ethylene bis (stearic acid amide), ethylene bis (isostearic acid) amide), ethylene bis(oleic acid amide), ethylene bis(12-hydroxystearic acid amide), ethylene bis(behenic acid amide)
, hexamethylene bis (stearic acid amide), hexamethylene bis (oleic acid amide), hexamethylene bis (behenic acid amide), m-xylylene bis (stearic acid amide), and the like.

The 2-bis(3,4-dimethylphenyl)ethane and higher fatty acid amide compound used in the present invention are milled using a grinding machine such as a ball mill, attrizer, or sand grinder, or an appropriate emulsifying device until the average particle size is 10. The particles are atomized to below microns, more preferably below 3 microns.

In this case, both may be atomized separately, but it is preferable to atomize both at the same time from the beginning, or to atomize each separately and then atomize both together again.

Further, a color-forming colorless dye, a color developer, and various other additive materials as required are atomized using a similar device, and these are combined to form a coating liquid.

This coating solution usually contains polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, polyacrylamide polymer, starch, styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-
Binders such as butadiene copolymers or modified products thereof, and fillers such as silane, kaolin, diatomaceous earth, talc, titanium dioxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, and melamine are blended.

Furthermore, in addition to these, metal soaps, waxes, light stabilizers, waterproofing agents, dispersants, antifoaming agents, etc. can be used.

By applying this coating liquid to paper and various films, the desired heat-sensitive recording material can be obtained.

The 1,2-bis(3,4 dimethylphenyl) ethane and higher fatty acid amide compounds used in the present invention,
It varies depending on the required performance and recording suitability, as well as the type and amount of other additives such as color-forming colorless dyes and color developers used, and is not particularly limited, but usually 1 part of color-forming dye is used. 0.05 to 10 parts of each are used.

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

Example-1 20 g of 3-dibutylamino-6-methyl-7-anilinofluorane and 10% aqueous polyvinyl alcohol solution
0 g was sufficiently ground to obtain dyed bone l5ji liquid (liquid A).

20 g of bisphenol A and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain a color developer dispersion (liquid B).

1.2-bis(3,4-dimethylphenyl)ethane 20
g, 3 g of a higher fatty acid amide compound (general grade commercial product) and 97 g of a 10% polyvinyl alcohol aqueous solution were thoroughly ground to prepare a sensitizer/higher fatty acid amide dispersion (C-
1 liquid) was obtained.

20g of 12-bis(3,4-dimethylphenyl)ethane
and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain a sensitizer dispersion (DI liquid).

For comparison, 20 g of 1,2-bis(2,4-dimethylphenyl)ethane and 3 g of higher fatty acid amide compound
and 97 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain a comparative sensitizer/higher fatty acid amide dispersion (C-2
liquid) and 1. 2-bis(2,4-dimethylphenyl)
20g of ethane and 10% polyvinyl alcohol aqueous solution
Thoroughly grind 00g and prepare a comparative sensitizer dispersion (Liquid D-2).
I got it.

20 g of a higher fatty acid amide compound and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain an amide dispersion (CE liquid).

In order to see the effect of simultaneously emulsifying and dispersing the diarylethane sensitizer and higher fatty acid amide compound, AI
Liquid, Bl liquid, C-1 liquid or C-2 liquid and finely powdered silica were mixed at a weight ratio of 1:2:2:0.5 and sufficiently dispersed to obtain a coating liquid.

AI
Mix liquid, Bl liquid, D-12 liquid, D2 liquid, E liquid and fine powdered silica in a ratio of 1:2:2:0.3:o, 5, and thoroughly disperse to form a coating liquid. I got it.

Apply each of the above coating liquids to a thickness of 28μ on a 50g/board base paper.
A heat-sensitive recording material was prepared by coating with m and drying.

Using the obtained thermal paper, the color density of the recorded image was printed by changing the pulse width using a thermal printing device (THPMD: manufactured by Okura Electric Co., Ltd.) using a Macbeth densitometer (RD manufactured by Macbeth Co., Ltd.).
-933 type). Furthermore, the density of the recorded image was similarly measured for the printed thermosensitive recording material which was stored for 5 hours in each atmosphere of 60''C drying and 90% relative humidity to determine the storage stability.

The results are shown in Table-1.

Table -1 Table = 1Continued Table■Continued Table■Continued Table 1Continued Table-1Continued Example-2 In order to examine the descriptions of higher fatty acid amide compounds based on their purity, higher fatty acid amide compounds of different purity were used as shown below. Each dispersion was prepared by the following procedure.

20g of 3-dibutylamino-6-methyl-7-anilinofluorane and 10% polyvinyl alcohol aqueous solution
0 g was sufficiently ground to obtain a dye dispersion (Liquid A).

20 g of bisphenol A and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain a color developer dispersion (liquid B).

20g of 12-bis(3,4-dimethylphenyl)ethane
, 3 g of stearic acid amide of different purity and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground to obtain a sensitizer/higher fatty acid amide dispersion (Liquid C-3).

A weight ratio of A liquid, B liquid, C-3 liquid and fine powder silica is 1.
:'2:2:0.5 and sufficiently dispersed to obtain a coating liquid.

This coating liquid was applied to a thickness of 28 μm on a 50 g/rrr base paper and dried to prepare a heat-sensitive recording material.

Using the obtained thermal paper, a test was conducted in the same manner as in Example-1.

The results are shown in Table-2.

In addition, in the table, stearic acid amide-1 is a commercially available general grade product, containing about 70% CI8 saturated fatty acid amide, and 28% CI6 saturated fatty acid amide,
Stearic acid amide-2 contains 2% by weight of C2゜ saturated fatty acid amide, stearic acid amide-2 contains 94% by weight of CIB saturated fatty acid amide, 6% by weight of C16 saturated fatty acid amide, and stearic acid amide-3 contains It is a purified product consisting only of CI8 saturated fatty acid amide.

As is clear from the results in Table-■, the sensitizer of the present invention (1
, 2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide compound) has a similar structure.
．． Compared to the case of using 2-bis(2,4-dimethylphenyl)ethane, it not only has extremely high color density but also has the advantage of less background fog and less color development at low energy. Since it has an extremely large effect of preventing the background portion from developing color or the printed portion from discoloring during storage, it is extremely useful for obtaining a heat-sensitive recording material with high sensitivity and good storage stability.

In particular, the effects of the present invention are obtained when 1,2-bis(3,4 dimethylphenyl)ethane and a higher fatty acid amide compound are simultaneously emulsified and dispersed (Table 1), or when 7 This is remarkable when one higher fatty acid amide type compound is used (Table 2).

Claims (9)

[Claims] (1) In a heat-sensitive recording material provided with a color-forming layer containing a normally colorless or light-colored color-forming substance and a color developer that causes the substance to develop color when heated, the color-forming layer contains 1 represented by the following formula:
, 2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide compound. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (2) The higher fatty acid amide compound has 12 or more carbon atoms.
The heat-sensitive recording material according to claim 1, which is an amide of 30 higher fatty acids. (3) The heat-sensitive recording material according to claim 1 or 2, wherein the higher fatty acid amide compound is stearic acid amide. (4) The heat-sensitive recording material according to claim 1 or 2, wherein the higher fatty acid amide compound is 12-hydroxystearic acid amide. (5) The higher fatty acid amide compound has 12 or more carbon atoms.
The heat-sensitive recording material according to claim 1, which is N-hydroxymethylamide of No. 30 higher fatty acid. (6) The heat-sensitive recording material according to claim 1 or 5, wherein the higher fatty acid amide compound is N-hydroxymethylstearic acid amide. (7) A higher fatty acid amide compound is an alkylene bis(
The heat-sensitive recording material according to claim 1, which is a higher fatty acid amide. (8) The heat-sensitive recording material according to any one of claims 1 to 7, wherein 1,2-bis(3,4-dimethylphenyl)ethane and a higher fatty acid amide compound are simultaneously emulsified and contained in the coloring layer. (9) The heat-sensitive recording material according to any one of claims 1 to 8, wherein the higher fatty acid amide compound contains 90% by weight or more of a single higher fatty acid amide compound.