JPS6233676A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To prevent the coloration of the texture part and the color erasing of the coloring part due to the possible contact with oils and plasticizers and to improve the light resistance of the texture part, by adding specific auxiliary components to the materials having leuco dye and specific developer to cause coloring reaction. CONSTITUTION:In the heat sensitive recording material utilizing the coloring reaction between leuco dye and its developer, the autipyrine complex of zinc thiocyanate expressed as a developer by formula (1) is used and at the same time, 4,4'-butylidene-bis(3-methyl-6-tertiary-butylphenol) is used as an auxiliary component. As to the amount of auxiliary component to be used, 1-10pt.wt. is suitable for 1pt.wt. of developer. As to the leuco dye, triphenyl methane series, fluorane series, phenothiazine series, auramine series, spiro pyrane series, indolino phthalide series, etc. should be preferably used. Further, in order to fix those components by bonding onto the basic materials, bonding agents such as, for instance, polyvinyl alcohol, starch and its derivative, methoxy cellulose, etc. are used.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a heat-sensitive recording material, and in particular, a heat-sensitive recording material that is excellent in color development and other recording properties, has good image stability, and has excellent light resistance in the background area. Regarding.

[Prior art]

General heat-sensitive recording materials are coated on a support such as paper or film, and contain a colorless or light-colored color-forming dye such as a leuco dye as a color-forming agent, and a phenolic compound (especially bisphenol A) as a color-developing agent that causes the dye to develop color when heated. In addition to the color forming system consisting of acidic substances such as organic acids, binders, fillers, sensitivity improvers,
? For example, one is provided with a heat-sensitive coloring layer in which l agent and other auxiliary agents are dispersed.

Special Publication No. 43-4160, Special Publication No. 45-14039,
It was introduced in Japanese Patent Application Laid-Open No. 48-27736 and has been widely used in practice. 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 of this, there is no need for complicated processing such as development and fixing compared to other recording materials.
Records can be obtained in a short time with a relatively simple device, II
Due to its low cost and low noise generation and environmental pollution, it is used for copying books, documents, etc., as well as for recording various information and measuring instruments such as electronic computers, facsimiles, telex machines, medical measuring instruments, etc. Useful as a material.

However, in the case of this type of leuco-based heat-sensitive recording material,
The disadvantage is that the stability of the recorded image is poor and, for example, the recorded image is easily discolored when it comes into contact with oils or plasticizers such as dioctyl phthalate contained in plastic films.

In order to solve this problem, we first used an antipyrine complex of zinc thiocyanate represented by the formula (I) below as a color developer for leuco dyes, which caused color development on the skin even when it came into contact with oils, plasticizers, etc. It has been found that a heat-sensitive recording material with extremely high image stability without decoloring of the colored portion can be obtained.

However, the only drawback of the antipyrine complex of zinc thiocyanate, which is the color developer used in the present invention, is that the color change (coloration) caused by light is greater than that of other ordinary color developers. The background part has the disadvantage that it is greatly discolored by light.

Conventionally, there is a method of using ultraviolet absorbers to improve light resistance, but when these agents are used in combination with the leuco dye and color developer of the present invention, fogging of the background and moisture resistant storage of the image area are avoided. There is a drawback that powder blowing sometimes occurs,
It was difficult to actually use it.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that does not develop color in the background area or decolorize the colored area due to contact with oils or plasticizers, and has excellent light resistance in the background area.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, an antipyrine complex of zinc thiocyanate represented by the following formula (I) is used as the color developer, and an auxiliary As a component, 4,4′ −
A heat-sensitive recording material characterized by using butylidene bis(3-methyl-6-tert-butylphenol) is provided.

Formula (I) Auxiliary component 4,4-butylidene bis (
The appropriate amount of 3-methyl-6-tert-butylphenol (3-methyl-6-tert-butylphenol) is 1 to 0.1 parts by weight per 1 part by weight of the color developer formula (I).

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. .

Specific examples of such leuco dyes include, for example.

Examples include those shown below.

3.3-bis(p-dibutylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(P- dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide.

3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzpluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilite fluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-
chloranilino)xantylbenzoic acid 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-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane.

3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, pen-diylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2 '-Hydroxy-47-diethylaminophenyl)-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)fluorane, pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N- Benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane.

3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-)-luidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7(p-n-
butylanilino) fluorane.

3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
, 5-penbifluorane etc.

In the present invention, in order to bind and support the leuco dye, color developer, and auxiliary components on the support, various conventional binders can be used as appropriate. For example, polyvinyl alcohol, starch and its derivatives, methoxy Cellulose derivatives such as cellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer , styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, styrene l-butadiene. Copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride
Latex such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In addition, in the present invention, in addition to the leuco dye, color developer, and auxiliary components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material may be added.

For example, fillers, surfactants, thermofusible substances (or lubricants)
etc. can be used together. In this case, the filler is 1
For example, calcium carbonate, silica.

In addition to inorganic fine powders such as zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica, urea-formalin resin, styrene/methacrylic acid copolymer, Organic fine powder such as polystyrene resin can be mentioned, and thermofusible substances include, for example, higher fatty acids or their esters, amides, or metal salts, various waxes, and combinations of aromatic carboxylic acids and amines. Condensates, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organic compounds that have a melting point of about 50 to 200°C Can be mentioned.

Furthermore, for the purpose of improving head matching properties and image stability, a water-soluble resin and an organic or inorganic filler can be provided as a protective layer on the heat-sensitive color former layer. In this case, the water-soluble resin can be appropriately selected from among the binders described above, and the filler can be selected from among the fillers described above. Further, in order to obtain a uniform coloring layer, an undercoat layer may be provided below the heat-sensitive coloring layer. As the material for the undercoat layer, the above-mentioned binder, filler, etc. are used.

〔effect〕

The heat-sensitive recording material of the present invention comprises a leuco dye and the general formula (I
) 4,4'-butylidene bis(3
- Methyl-6-tert-butylphenol), this heat-sensitive recording material has excellent light resistance in the background area and does not develop color in the background area or discoloration in the colored area due to contact with oils and plasticizers. be.

〔Example〕

Next, the present invention will be further explained by examples.

Note that all parts and percentages shown below are based on weight.

[A liquid]

3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-7 nylinofluorane 10 parts Polyvinyl alcohol 10% aqueous solution 10 Water
30〃
[Liquid B] Formula (I) antipyrine complex of zinc thiocyanate 20 parts 10% polyvinyl alcohol aqueous solution 20 water
6
0 [Liquid C] 4.4'-Butylidenebis(3-methyl-6-tert-butylphenol) 20 parts Polyvinyl alcohol 10% aqueous solution 20 Water
6
0 [Liquid D] Stearic acid amide 20 parts Calcium carbonate IQn polyvinyl alcohol 10% aqueous solution 25 Water
551! Each of the mixtures having the above compositions was dispersed using a ball mill so that the average particle size was 3 to 5 μm.

Example 1 15 parts of the dispersion liquid A, 55 parts of liquid B, 15 parts of liquid C, 45 parts of liquid D and 30 parts of water were mixed to form a heat-sensitive coloring layer coating liquid.

An undercoat layer was provided on a high-quality paper with a basis weight of 45 g/rrr so that a coating solution of fine urea-formalin resin powder and styrene/butadiene copolymer emulsion in a weight ratio of 4=1 was dried so that the adhesion amount was 5 g/rrr. Ta.

It was then prepared on the undercoat as described above.

A heat-sensitive coloring PR coating liquid was applied and dried at a dry deposition amount of 6.5 g/rrF. On the heat-sensitive coloring layer thus formed, silicon dioxide fine powder and polyvinyl alcohol =
A protective layer coating liquid with a weight ratio of 1:1 has a dry coating weight of 2g.
The thermal paper of the present invention was obtained by coating and drying to obtain Ird and calendering.

Comparative Example 1 A comparative example sample was obtained in the same manner as in Example 1 except that water was added instead of liquid C in Example 1.

The heat-sensitive recording material obtained as described above was printed using a commercially available thermal gradient tester at 140°C for 1 second, and the image density sample at this time was printed at 40°C and 90% RH. It was left to stand for 24 hours and tested for the presence or absence of powder blowing. Further, the skin sample was exposed to a 5,0001 ux fluorescent lamp for 100 hours, and the change in concentration was tested. The densitometer used was Macbeth RD-514, filter No. 47. The results are shown in Table-1.

Table-1

Claims (1)

[Claims] A heat-sensitive recording material that utilizes a color reaction between a leuco dye and its color developer, in which an antipyrine complex of zinc thiocyanate represented by the following formula (I) is used as the color developer, and as an auxiliary agent. As a component, 4,4'-butylidene bis(
3-Methyl-6-tert-butylphenol). Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼