JPH0651426B2 - Thermal recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a heat-sensitive recording material containing a leuco dye as a color former.

[Prior art]

The heat-sensitive recording material is generally a paper, a synthetic paper, a plastic film or the like provided with a heat-sensitive image-forming layer containing a heat-coloring composition as a main component on a support, and a heat head, a heat pen, a laser beam,
A colored image can be obtained by heating with a strobe lamp or the like. This kind of recording material is a phenomenon compared to other recording materials,
Due to the advantages of being able to obtain recording in a short time with a relatively simple device without performing complicated processing such as fixing, low noise and environmental pollution, and low cost,
In addition to being used for copying books and documents, it is widely used as a recording material in various fields such as electronic calculators, facsimiles, ticket vending machines, labels and recorders. The thermochromic composition used for such a heat-sensitive recording material is composed of a general color former and a color developer that allows 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 organic acids and phenolic substances have been conventionally used as color developers. The recording material in which the color-developing agent and the color-developing agent are combined has the advantage that the color tone of the obtained image is particularly clear, the background whiteness is high, and the light resistance of the image is excellent. It's being used.

Conventionally, as a developer for leuco dyes, bisphenol A and p-hydroxybenzoic acid esters and the like have been used, but these phenols have high color density, but lack stability of a color image, There is a problem that the concentration is lowered when left to stand naturally, and that the concentration is lowered even when it is contacted with oils and fats such as fingerprints. These phenomena occur not only when using phenols but also when using general organic acids, and it is strongly desired to overcome them. As disclosed in JP-A-59-38091, it has been proposed to use aluminum chloride as at least a part of the developer as a developer that gives an image with good stability. According to the above method, a highly reliable thermal paper with almost no decoloration of an image is provided, but there is a drawback that the background density is high because liquid fog occurs at the time of preparation of the thermal liquid.

〔Purpose〕

An object of the present invention is to provide a heat-sensitive recording material in which the above-mentioned conventional drawbacks have been improved, that is, it has high sensitivity and is free from background fogging due to humidity, and may be erased when it comes into contact with a plasticizer or oil. The object is to provide a heat-sensitive recording material that does not have the

〔Constitution〕

According to the present invention, on a support, in a thermosensitive recording material comprising an undercoat layer and a thermosensitive coloring layer laminated in that order, a metal salt of a salicylic acid compound represented by the following general formula (I) and a zinc compound. There is provided a heat-sensitive recording material comprising one of the components contained in the undercoat layer and the other component contained in the thermosensitive color developing layer.

(In the formula, M represents a metal atom such as magnesium, calcium, strontium, barium, aluminum, tin, or lead, and m represents a valence of M. R represents a hydrogen atom, or an alkyl group, an aryl group, an alkoxy group, Represents a substituent such as an aralkyl group, a halogen atom, etc. n represents an integer of 1 to 4, and when n is 2 or more, each R may be the same or different. Examples of salicylic acid compounds to be obtained include, but are not necessarily limited to, the following.

Specific examples of the zinc compound used in the present invention include, for example,
Zinc oxide, zinc hydroxide, zinc fluoride, zinc benzoate, P
-Zinc tert-butyl benzoate, zinc salicylate, zinc stearate, zinc myristate, zinc laurate,
Inorganic and organic compounds such as zinc benzoin, zinc acetylacetonate, zinc p-toluenesulfonate, zinc octylsulfonate, zinc p-tertiarybutylsulfonate, zinc dimethylglyoxyl, and zinc xanthate are mentioned. It is not limited to.

The zinc compound used in the present invention is used in a proportion of 0.2 to 5.0 parts by weight with respect to 1 part by weight of the color developer including a metal salt of a salicylic acid compound.

As the developer used in the present invention, in addition to the metal salt of the salicylic acid-based compound, if necessary, a conventionally known phenolic substance, or a developer consisting of an inorganic / organic acidic substance and its derivative is used. It can also be used together. The color developer used in the present invention is generally used in the range of 1 to 10 parts by weight, preferably 2 to 6 parts by weight, based on 1 part by weight of the leuco dye, but the metal of the salicylic acid compound used in the present invention is used. The amount of the color-developing agent composed of a salt is 20% by weight or more, preferably 50% by weight or more, based on the total amount of the color-developing agents.

The leuco dye used in the present invention is applied alone or in combination of two or more, as such a leuco dye,
What is applied to this type of heat-sensitive material is arbitrarily applied, and for example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophtalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet letolactone), 3,3-bis ( p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexyl Amino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benz Fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-
Anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino}
-6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) Fluoran, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 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) fluorane, benzoyl Leucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrilospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrolispirane, 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-triofluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinoflu Oran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro -7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenyl) Amino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-cu B-3-(N-Mechirutoruijino) -7- (p-n- butylanilino) fluoran, 3- (N-benzyl--N- cyclohexylamino) -5,6
Benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ′,
5'-benzofluorane, 3,6-dimethoxyfluorane, 3- (p-dimethylaminophenyl) -3-phenylphthalide, 3-di (1-ethyl-2-methylyldol) -3-yl-phthalide , 3-diethylamino-6-phenyl-7-azafluorane, 3,3-bis (p-diethylaminophenyl) -6-dimethylamino-phthalide, 2-bis (p-dimethylaminophenyl) methyl-5-dimethylamino -Benzoic acid, 3- (p-dimethylaminophenyl) -3- (p-dibenzylaminophenyl) phthalide, 3- (N-ethyl-Nn-amyl) amino-6-methyl-7 −
Anilino Fluoran, etc.

In the present invention, as the color developer that can be used in combination with the color developer comprising a metal salt of a salicylic acid compound, various electron-accepting substances that react with the leuco dye when heated to develop a color thereof are applied. Specific examples include the following phenolic substances, organic or inorganic acidic substances, their esters and salts, and the like.

Gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3
-Cyclohexyl salicylic acid, 3,5-di-tert-butyl salicylic acid, 3,5-di-α-methylbenzyl salicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol) ), 4,4′-isopropylidene bis (2,6-dibromophenol), 4,4 ′
-Isopropylidene bis (2,6-dichlorophenol),
4,4'-isopropylidene bis (2-methylphenol),
4,4'-isopropylidene bis (2,6-dimethylphenol), 4,4'-isopropylidene bis (2-tert-butylphenol), 4,4'-sec-butylidene diphenol, 4,
4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis (2-methylphenol), 4-tert-
Butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak-type phenol resin , 2,2'-thiobis (4,6-dichlorophenol), catechol, resorcin, hydroquinone, pyrogallol, phloroglysin, phloroglysincarboxylic acid, 4-tert-octylcatechol, 2,2'-
Methylenebis (4-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butalphenol), 2,2 '
-Dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-
Hydroxybenzoic acid-p-chlorobenzyl, p-hydroxybenzoic acid-o-chlorobenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-
Octyl, benzoic acid, 1-hydroxy-2-naphthoic acid,
2-hydroxy-6-naphthoic acid, 4-hydroxydiphenyl sulfone, 4-hydroxy-4'-chlorodiphenyl sulfone, bis (4-hydroxyphenyl) sulfide, 2
-Hydroxy-p-toluic acid, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivative, 4-hydroxythiopheneol derivative and the like.

In the present invention, in order to bond and support the leuco dye, the color developer and the zinc compound on the support, various conventional binders can be appropriately used, and specific examples thereof include
For example, the following can be mentioned.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali In addition to water-soluble polymers such as salt, polyacrylamide, sodium alginate, gelatin, casein,
Polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic ester,
Latex etc. such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene / acrylic copolymer.

Further, in the present invention, together with the leuco dye and the color developer, if necessary, further auxiliary components commonly used in this type of heat-sensitive recording material, for example, a filler, a surfactant, a heat-fusible substance ( Alternatively, a lubricant) or the like can be used in combination. In this case, as the filler, for example, calcium carbonate, silica,
Tyran oxide, aluminum hydroxide, barium sulfate, clay, talc, inorganic fine powder such as surface-treated calcium and silica, as well as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin and other organic Fine powder can be mentioned. Examples of the heat fusible substance include, for example, higher fatty acids or esters, amides or metal salts thereof, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, 3 50,4-epoxy-dialkyl hexahydrophthalate, higher ketones and other heat-fusible organic compounds
One having a melting point of about 200 ° C. is mentioned.

The heat-sensitive recording material of the present invention includes, for example, an undercoat layer coating liquid and a heat-sensitive layer-forming coating liquid containing the above components, paper,
It is produced by coating on a suitable support such as synthetic paper or plastic film and drying, and is applied to various recording fields.

[Effect]

As described above, the heat-sensitive recording material of the present invention contains a metal salt of a salicylic acid-based compound that acts as a color developer, and a zinc compound separately in the undercoat layer and the heat-sensitive color forming layer. Compared to thermal recording materials,
It is excellent in that it has high sensitivity, does not have background fog under high humidity and high temperature, and does not discolor when contacted with a plasticizer or oil.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples. The parts and% shown below are based on weight.

Example 1 A mixture having the following composition was separately pulverized and dispersed in a sand grinder for 1 to 2 hours to prepare a solution [A], a solution [B], a solution [C] and a solution [D].

[A liquid]

3-N-methyl-3-N-cyclohexylamino-6-methyl-7-anilinofluorane 200 parts 10% polyvinyl alcohol aqueous solution 200 parts water 600 parts [solution B] 10% polyvinyl alcohol aqueous solution 200 parts calcium salicylate 200 parts Water 600 parts [Solution C] Zinc stearate 200 parts 5% Methylcellulose aqueous solution 400 parts Water 400 parts [Solution D] Calcium carbonate 200 parts N-stearylbenzamide 50 parts 5% Methylcellulose aqueous solution 200 parts Water 550 parts As above Using the obtained liquids [A] to [D], a thermosensitive color developing layer coating liquid and an undercoat layer coating liquid having the following compositions were prepared.

Thermosensitive color developing layer coating liquid (1) Liquid 100 parts (2) [C] liquid 300 parts (3) [D] liquid 800 parts Undercoat layer coating liquid (1) [B] liquid 400 parts (2) Styrene -Acrylic copolymer 100 parts (organic filler) (3) 40% SBR emulsion 50 parts (4) Water 450 parts Next, the above undercoat layer coating liquid is dried on 52 g / m ² (basis weight) commercial fine paper. After coating and drying with a wire bar so that the coating amount is 4.2 g / m ² to form an undercoat layer, the above thermosensitive coloring layer coating liquid is dried on the upper layer so that the coating amount is 7.4 g / m ² A thermosensitive coloring layer was formed by coating and drying with a wire bar, and then a calender was applied so that the surface smoothness was 500 to 1000 sec to prepare a thermosensitive recording material of Example 1 of the present invention.

Example 2 Example of the present invention except that zinc hydroxide was used instead of zinc stearate in [C liquid] in Example 1.
A thermal recording material of 2 was prepared.

Example 3 A thermosensitive recording material of Example 3 of the present invention was prepared in the same manner as in Example 1 except that barium salicylate was used in place of the calcium salicylate salt of [B liquid].

Example 4 A heat-sensitive recording material of Example 4 of the present invention was prepared in the same manner as in Example 1, except that the calcium salt of salicylate of [B liquid] in Example 1 was replaced with the calcium salt of 3-phenylsalicylic acid.

Example 5 In Example 1, the solution [B] was used instead of the solution [C] of the thermosensitive color developing layer coating solution, and the following solution [E] was used instead of the solution [B] of the undercoat layer coating solution. In the same manner as in Example 1, a thermal recording material of Example 5 of the present invention was prepared.

[E] Liquid zinc xanthate 200 parts 5% aqueous solution of methylcellulose 400 parts water 400 parts Comparative Example 1 Instead of the salicylic acid calcium salt of [B liquid] of Example 1,
A heat-sensitive recording material of Comparative Example 1 was prepared in the same manner except that bisphenol A was used.

Comparative Example 2 A thermosensitive recording material of Comparative Example 2 was prepared in the same manner except that the solution [C] was omitted from the thermosensitive color developing layer coating solution of Example 1.

Comparative Example 3 Liquid [A]: Example 1 except for the undercoat layer of Example 1.
Undercoat layer coating liquid: [C] liquid: [D] liquid = 1: 8:
To prepare a thermosensitive color developing layer coating liquid by mixing and stirring at a ratio of 3: 8 (weight ratio), so that the dry coating amount of this coating liquid is 11.6 g / m ² ,
A thermosensitive recording material of Comparative Example 3 was prepared by coating and drying with a wire bar.

The above heat-sensitive recording materials were tested for color density and erasability by oil and plasticizer. The results are shown in Table-1.
It was shown to. The test method was as follows.

1. Maximum density: The color development part when a thermal block of 150 ° C. was contacted for 2 seconds at a pressure of 2 kg / cm ² was measured with a Macbeth densitometer RD-514 (Fluter: w-106).

2. Background density: The uncolored part of the obtained sample was measured with a Macbeth densitometer RD-514 (Fluta: w-106).

3. Oil resistance: After the cottonseed oil was adhered to the printed portion where the concentration was measured, the concentration was measured after leaving it at 40 ° C Dry for 24 hours.

4. Plasticizer resistance: A plasticizer (DOA) was adhered to the printed portion whose density was measured, and the density was measured after leaving it at 40 ° C Dry for 24 hours.

5. Background Fog at Humidity [Humidity Fog]: The uncolored part of the obtained sample was left at 40 ° C. and 90% RH for 24 hours, and the density was measured.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising an undercoat layer and a thermosensitive coloring layer laminated in this order on a support, wherein either a metal salt of a salicylic acid compound represented by the following general formula (I) or a zinc compound is used. A thermosensitive recording material comprising one of the components contained in the undercoat layer and the other component contained in the thermosensitive coloring layer. (In the formula, M represents a metal atom such as magnesium, calcium, strontium, barium, aluminum, tin, or lead, and m represents a valence of M. R represents a hydrogen atom, or an alkyl group, an aryl group, an alkoxy group, Represents an aralkyl group, a substituent such as a halogen atom, etc. n represents an integer of 1 to 4, and when n is 2 or more, each R may be the same or different.)