JP2787079B2 - Thermal recording material - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a developer.

[Conventional technology]

A thermosensitive recording material generally has a thermochromic layer mainly composed of a thermochromic composition provided on a support such as paper, synthetic paper, plastic film, etc., and has a heat head, a hot pen, a laser beam, a strobe, a lamp, and the like. Thus, a colored image can be obtained by heating. Compared to other recording materials, this type of recording material allows recording to be performed in a short time with a relatively simple apparatus without performing complicated processing such as development and fixing, and generates less noise and environmental pollution. Due to its advantages such as low cost and low cost, it is widely used as a recording material in various fields.

In particular, in recent years, heat-sensitive recording materials have been used as recording materials for merchandise information, sales management, and systemization of commodities corresponding to the POS (Point of Sale) system. The thermochromic composition used in such a thermosensitive recording material generally comprises a color former and a color developer that causes the color former to develop color when heated,
For example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring is used as a color former, and an organic acid or a phenolic substance is conventionally used as a color developer. A recording material in which this color former and a developer are combined has the advantages that the obtained image has a clear color tone and high whiteness of the background, and is widely used. For this reason, heat-sensitive coloring paper is often used for wrapping paper, food labels, and the like. However, there is a problem that images are discolored and the background is fogged by the influence of fingerprints, oils, and plasticizers of food wraps. Some of these phenomena occur when not only phenols but also general organic acids are used, and there is a strong demand for overcoming them. As a method for improving the plasticizer resistance and oil resistance, it is conventionally known to use a protective layer on a thermosensitive coloring layer, but the plasticizer resistance and oil resistance are not satisfied. Japanese Patent Application Laid-Open No. 60-208286 proposes a heat-sensitive recording material using bis (3-allyl-4-hydroxyphenyl) sulfone. There is a problem that the part develops color. Therefore, the fact is that a heat-sensitive recording material satisfying plasticizer resistance and oil resistance and having no coloring on the background has not yet been known.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which is excellent in plasticizer resistance and oil resistance and has no coloration in the background.

[Means for solving the problem]

According to the present invention, in a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a developer, the undercoat layer contains bis (3-allyl-4-hydroxyphenyl) sulfone and maleic anhydride as main components. A heat-sensitive recording material characterized by containing a polymer is provided.

That is, the present invention is characterized in that bis (3-allyl-4-hydroxyphenyl) sulfone and a maleic anhydride copolymer are contained in the undercoat layer.

Specific examples of the copolymer mainly containing maleic anhydride include polydiisobutylene / maleic anhydride, isobutylene / maleic anhydride amide ammonium salt, and styrene / maleic acrylic copolymer.
It is not limited to this.

Thus, a thermosensitive recording material having an undercoat layer formed from at least a copolymer containing bis (3-allyl-4-hydroxyphenyl) sulfone and maleic anhydride as main components has a plasticizer resistance and an oil resistance. It is excellent and has very little coloration in the background.

A thermosensitive recording material in which the undercoat layer does not contain either bis (3-allyl-4-hydroxyphenyl) sulfone or a copolymer containing maleic anhydride as a main component has a reduced plasticizer resistance and oil resistance. The background portion develops color, and a remarkable effect as in the present invention is not exhibited.

Various fillers generally used can be used for the undercoat layer of the present invention as needed.
As the filler in that case, for example, calcium carbonate,
Silica, zinc oxide, aluminum hydroxide, zinc hydroxide,
In addition to inorganic fine powders such as barium sulfate, clay, talc, and surface-treated calcium and silica, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be given. .

As the binder used in the undercoat layer of the present invention, generally known water-soluble polymers and water-soluble emulsions are used. Specific examples include the following.

Polyvinyl alcohol, starch and derivatives thereof, hydroxymethyl cellulose, hydroxyethyl cellulose,
Cellulose derivatives such as carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, sodium alginate, gelatin, casein, etc. In addition to water-soluble polymers, emulsions such as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene copolymer Latexes such as polymers and styrene / butadiene / acrylic copolymers.

Further, as a component constituting the undercoat layer, a surfactant, a lubricant and the like can be used together with the filler and the binder.

Here, the filler in the undercoat layer, the screw (3
The amount of the copolymer consisting of (allyl-4-hydroxyphenyl) sulfone and maleic anhydride is suitably 10 to 50% by weight, 10 to 50% by weight, and 10 to 30% by weight, respectively. The coating amount of the layer is suitably 0.5 to 4 g / m ² .

The leuco dyes used in the present invention are applied alone or as a mixture of two or more types. As such leuco dyes, those applied to this type of recording material are arbitrarily applied. Leuco compounds of dyes such as methane, fluoran, phenothiazine, auramine, spiropyran and indolinophthalide are preferably used. Specific examples of such leuco dyes include, for example, those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-
Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3 -Bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran, 3- (N-methyl-N-isobutylamino) -6 Methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methyl Fluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofur Orchid, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- {N- (3 '-Trifluoromethylphenyl) amino {-6-diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthyl benzoate lactam}, 3-diethylamino-6-methyl-7 -(M-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-N-methyl-N-amylamino-6- Methyl-7
-Anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl -7- (2 ', 4'-
Dimethylanilino) fluoran, 3- (N, N-diethylamino) -5-methyl-7-
(N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-
Pyrirospiran, 6'-bromo-3'-methoxy-benzoindolino-
Pyrirospiran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl)- 3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- ( 2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-
Methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N -Benzyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluoran, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluoran, 3 -(N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7- (α -Phenylethylamino) fluoran, 3-diethylamino-7-piperidi Fluoran, 2-chloro-3-(N-Mechirutoruijino) -7-
(Pn-butylanilino) fluoran, 3- (N-methyl-N-isopropylamino) -6
Methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro (9,
3 ')-6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino)-
5,6-benzo-7-α-naphthylamino-4′-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N- (2-ethoxypropyl) amino -6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluoran, 3- (p-dimethylaminophenyl) -3- {1,1-
Bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-
Bis (p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p
-Dimethylaminophenylethylene-2-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (1-p
-Dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2'-methoxy) -3
-(1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3- (4'-dimethylamino-2'-benzyloxy) -3 -(1 "-p-dimethylaminophenyl-1"
-Phenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,3- Bis {2- (p-dimethylaminophenyl)-
2- (p-methoxyphenyl) ethenyl} -4,5,6,7-
Tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane and the like.

In the present invention, as the developer used, various compounds having an electron accepting property, for example, a phenolic compound,
Thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof can be used in combination, and specific examples thereof include the following.

4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis (o-methylphenol), 4,4'-secondarybutylidenebisphenol, 4,4'-isopropylidenebis (2-tert-butylphenol), 4,4'-cyclohexylidenediphenol, 4,4'-isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis ( 4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-)
2-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-
Tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-
Cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-2-methylphenol), 4,4'-diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4 '-Hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuylate, stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea , Salicylanilide, 5-chloro-salicylanilide, bis- (4 (Hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4 '-Diphenolsulfone, 2,2'-diallyl-4,4'-diphenolsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, zinc 1-acetyloxy-2-naphthoate, 2-acetyl Zinc oxy-1-naphthonate, zinc 2-acetyloxy-3-naphthoate, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, an antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, Tetrabromobisphenol S and the like.

In order to manufacture the recording material of the present invention, as a binder for binding and supporting a leuco dye and a developer on the undercoat layer, various conventional binders can be appropriately used, and specific examples thereof are given below. The following are mentioned, for example.

Polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate /
Water-soluble polymers such as methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and polyacetic acid Vinyl, polyurethane, polyacrylate,
Emulsions such as polymethacrylic acid esters, vinyl chloride / vinyl acetate copolymers, ethylene / vinyl acetate copolymers, and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers.

When a thermosensitive recording material is obtained according to the present invention, various heat-fusible substances can be used as a heat sensitivity improver, if necessary, and specific examples thereof include the following compounds.

Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-pendyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate , Diphenyl carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-bis (phenoxy) ethane, 1 , 2 -Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy)
Ethane, 1,4-bis (phenoxy) butane, 1,4-bis (phenoxy) -2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-
Bis (phenylthio) butane, 1,4-bis (phenylthio) -2-butene, 1,2-bis (4-methoxyphenylthio) ethane, 1,3-bis (2-vinylilioxyethoxy) benzene, 4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3
-Dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbomoyl-p -Methoxycarbonylbenzene, N-octadecylcarbamoylbenzene and the like.

In the case of obtaining a thermosensitive recording material according to the present invention, together with a leuco dye and a developer, if necessary, auxiliary additives commonly used in this type of thermosensitive recording material, such as a filler and a surfactant, are used in combination. can do. In this case, as the filler, for example, other than inorganic fine powder such as calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, etc. Organic fine powder such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin.

In the present invention, a protective layer can be provided on the thermosensitive coloring layer, if necessary. In such a case, the filler, the binder, the heat-fusible substance, the surfactant and the like can be used as the components constituting the protective layer.

To prepare the heat-sensitive recording material of the present invention, an aqueous solution mainly containing a filler, bis (3-allyl-4-hydroxyphenyl) sulfone and a polymer containing maleic anhydride is placed on a support such as paper or synthetic paper. An undercoat layer is formed by coating and drying, and an aqueous solution containing a leuco dye, a color developer and a binder as main components may be further coated and dried thereon. Here, the amounts of the leuco dye, the developer and the binder used in the thermosensitive coloring layer are 2 respectively.
The amount is suitably from 30 to 30% by weight, from 10 to 80% by weight, from 1 to 20% by weight, and the amount of the heat-sensitive coloring layer formed is suitably from about ² to 10 g / m ² .

〔effect〕

The heat-sensitive recording material of the present invention contains a copolymer containing bis (3-allyl-4-hydroxyphenyl) sulfone and maleic anhydride as main components in the undercoat layer. And very little coloration in the background.

〔Example〕

Hereinafter, examples of the present invention will be described. All parts and percentages shown below are based on weight. Each liquid was dispersed and dispersed in a ball mill so that the average particle diameter of the contained particles was 5 μm.

Example 1 [Solution A] Styrene / methacrylic acid random copolymer 10 parts Bis (3-allyl-4-hydroxyphenyl) sulfone 10 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 10 parts 402W (manufactured by Nippon Kasei Polymer, main component polydiisobutylene / maleic anhydride)
5: 0.5, and then uniformly stirred and mixed to obtain a dry adhesion of 2-3 g / m ^{2 on} a high-quality paper having a basis weight of 50 g / m ^2.
Was applied and dried to form an undercoat layer of the present invention.

[B liquid]

3-N-cyclohexyl-N-methylamino-6-methyl-7-anilinofluoran 10 parts Polyvinyl alcohol 10% aqueous solution 10 parts Water 30 parts [Solution C] 1,7-bis (4-hydroxyphenylthio)- 3,5-Dioxaheptane 3.0 parts 4,4'-thiobis (6-t-butyl-3-methylphenol) 2.0 parts Calcium carbonate 3.0 parts 10% aqueous solution of polyvinyl alcohol 5 parts Water 27 parts [Solution D] Polyvinyl alcohol 10 % Aqueous solution 100 parts Calcium carbonate 10 parts Zinc stearate 1 part Water 14 parts [B solution] and [C solution] obtained as above are weighed, uniformly stirred and mixed, and placed on the undergoat layer. dry coating weight of coating and drying so that 0.4 to 0.5 g / m ² in the dye standards to form the thermosensitive coloring layer. Next, in [D solution], polyamide epichlorohydrin was added to polyvinyl alcohol.
40% was added, and the mixture was uniformly stirred and mixed, and coated and dried on the heat-sensitive coloring layer so that the dry adhesion amount was 2.5 to 4.5 g / m ² , to obtain a heat-sensitive recording material of the present invention.

Example 2 The same procedure as in Example 1 except that Tesfan in the undercoat layer was used.
A heat-sensitive recording material of Example 2 was prepared in the same manner except that 402W was changed to ammonium salt of Isovan 304D (manufactured by Kuraray Co., Ltd., main component: isobutylene / maleic anhydride).

Example 3 The same procedure as in Example 1 was carried out except that the test
402W was converted to Liquid LC-1 (Shinsei Chemical Co., Ltd.
A heat-sensitive recording material of Example 3 was prepared in the same manner except that a maleic acid acrylic copolymer) was used.

Comparative Example 1 In Example 1, the following [Solution E] was used instead of [Solution A].
A heat-sensitive recording material of Comparative Example 1 was prepared in the same manner except that.

[E liquid]

Styrene / methacrylic acid random copolymer 10 parts Bis (4-hydroxy-3,5-dibromophenyl) sulfone 10 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 10 parts Comparative Example 2 In Example 1, no Tesphan 402W was added. A heat-sensitive recording material of Comparative Example 2 was prepared in the same manner as described above except that the heat-sensitive recording material was used.

Various tests described below were performed on the heat-sensitive recording material prepared as described above. Table 1 shows the results.

Color development: Measured with a Macbeth densitometer at the color development area and the background area when the color was developed at 150 ° C. using a thermal gradient tester.

Plasticizer resistance: Using a thermal gradient tester, the colored part and the ground part that were colored at 150 ° C were stacked in three layers at a temperature of 40 ° C and a weight of 5 kg for 16 hours. And the density change of the background part was measured with a Macbeth densitometer.

Oil resistance: Using a thermal gradient tester, apply color of cottonseed oil to the color-developed area at 150 ° C and the skin area, and measure the density of the color-developed area and the skin area after 16 hours under 40 ° C test conditions with a Macbeth densitometer. .

Heat resistance: A sample that had been colored at 150 ° C. using a thermal gradient tester was allowed to stand at 70 ° C. for 1 hour, and the background density was measured with a Macbeth densitometer.

 Table 1 shows the above results.

As can be seen from the above results, the product of the present invention is extremely excellent in plasticizer resistance and oil resistance and has little background fog.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-260384 (JP, A) JP-A-61-160292 (JP, A) JP-A-61-199985 (JP, A) JP-A-61-1999 199986 (JP, A) JP-A-64-67380 (JP, A) JP-A-62-53877 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/28-5 / 34

Claims (1)

(57) [Claims] In a heat-sensitive recording material utilizing a color development reaction between a leuco dye and a developer, bis (3) is contained in an undercoat layer.
(Allyl-4-hydroxyphenyl) sulfone and a maleic anhydride-based copolymer.