JPS6327194B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a self-coloring pressure-sensitive recording sheet using color-forming agent-containing microcapsules made of synthetic polymer walls, and particularly relates to a method for producing a self-coloring pressure-sensitive recording sheet with high color density. be. Conventionally, various types of pressure-sensitive recording sheets are known, but a layer containing microcapsules containing a coloring agent (hereinafter referred to as
This is called the "capsule layer." ) and a layer containing a color developer that develops color upon contact with the color former (hereinafter referred to as the "color developer layer"). (3) A capsule layer is provided as a lower layer and a color developer layer is provided as an upper layer on the same side of the support; (3) A color developer layer is provided as a lower layer and a capsule layer is provided as an upper layer on the same side of the support. Things, (3)
Some are known in which microcapsules and a color developer are contained in one layer. In addition, methods for providing a capsule layer, a color developer layer, and a mixed layer of microcapsules and color developer on the support include an air knife coating method (for example, U.S. Pat. No. 3,186,851, U.S. Pat. No. 3,472,674, etc.), Coating method (for example, Japanese Patent Publication No. 49-35330, etc.), curtain coating method (for example, Japanese Patent Publication No. 53-2108, etc.)
However, in recent years, curtain coating methods have been attracting attention because they allow simultaneous multilayer coating, high-speed coating, and the ability to obtain a coating film with a smooth surface. Methods for producing microcapsules containing coloring agents include the complex coacervation method (US Pat. No. 2,800,457, US Pat. No. 2,800,458, etc.), the internal polymerization method (US Pat.
45133, 49-26848, 50-22507, U.S. Pat.
No. 446, No. 42-771, No. 42-2882, No. 42-2883
No. 42-8693, No. 42-8923, No. 42-9654
No. 42-11344, U.S. Patent No. 3429827, U.S. Pat.
3432327, 3577515, etc.), external polymerization method (Japanese Patent Publication No. 38-12518, 37-12380, U.S. Patent No.
No. 3516846, No. 3516941, No. 3594328, No.
No. 4087376, No. 4089802, No. 4100103, etc.), but self-coloring pressure-sensitive recording sheets have microcapsules obtained by internal polymerization or interfacial polymerization that improve the density of the wall. Excellent and especially useful. When producing microcapsules by internal polymerization or interfacial polymerization, it is necessary to disperse and emulsify an oily liquid in which a color former is dissolved in a polar liquid such as water that forms a continuous phase. Gelatin, gum arabic,
Casein, carboxymethylcellulose, starch, polyvinyl alcohol, etc. are commonly used.
However, among these protective colloids, gum arabic, casein, carboxymethyl cellulose,
Starch, etc., has no emulsifying power at a concentration of about 10%,
In order to obtain the desired drop size for microcapsules for self-coloring pressure-sensitive recording sheets, extremely strong stirring is required, and on the other hand, concentrations exceeding 10% have emulsifying power but are expensive, making them generally difficult to use. Gelatin also has the disadvantage that it is difficult to use at room temperature because its viscosity changes rapidly at the gelation point of 20 to 25°C, and coating solutions prepared using it also tend to have high viscosity. It was hot. Furthermore, although polyvinyl alcohol has excellent emulsifying power and a desired oil drop size can be obtained at room temperature and at a concentration of around 10%, polyvinyl alcohol reduces the activity of the color developer, so the microcapsules and the color developer may come into contact with each other. Self-coloring pressure-sensitive recording sheets had the disadvantage of reduced coloring ability. In particular, in the case of self-coloring pressure-sensitive recording sheets with a mixed layer of microcapsules and color developer,
When a microcapsule layer and a color developer layer are coated on a support at the same time in an overlapping relationship using a curtain coating method, or after coating a microcapsule layer or a color developer layer, other layers may be When overlapping layers are applied, the microcapsules and the color developer come into contact with each other in a wet state, so the activity of the color developer due to polyvinyl alcohol is further reduced, resulting in insufficient color development ability and the desired color development. In order to obtain the desired performance, it is necessary to increase the amount of coating, which has the drawback of increasing costs accordingly. The purpose of the present invention is, first, to provide a method for manufacturing a self-coloring pressure-sensitive recording sheet with high coloring properties, and second, to provide a method for manufacturing a self-coloring pressure-sensitive recording sheet at low cost. be. The object of the present invention is to form a synthetic polymer wall by emulsifying and dispersing this oily liquid in the presence of carboxy-modified polyvinyl alcohol when encapsulating an oily liquid in which a color former is dissolved by an interfacial polymerization method or an internal polymerization method. This is achieved by forcing people to do something. In the present invention, the carboxy-modified polyvinyl alcohol has a carboxy-modified amount of 1 to 10 mol%, preferably 2 to 10 mol%, and more preferably
The amount used is 2.5 to 5.5 mol% and the degree of saponification is 80 to 95%, preferably 80 to 85%. If the amount of carboxy modification is less than 1%, the coloring properties of a self-coloring pressure-sensitive recording sheet will be reduced, and if it exceeds 10%, the fluidity of the microcapsule liquid will be reduced, causing problems in coating. Also, the degree of saponification
If it is less than 80%, the emulsifying power is low and a powerful stirrer must be used to obtain the desired capsule size, while if it exceeds 95%, emulsification becomes impossible. For carboxy modification of the carboxy-modified polyvinyl alcohol according to the present invention, carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, crotonic acid, maleic acid, fumaric acid, maleic anhydride, etc. are used, especially itaconic acid. , itaconic anhydride, acrylic acid, methacrylic acid, etc. are useful. As a method for producing carboxy-modified polyvinyl alcohol, those described in Japanese Patent Publication No. 44-5331, Japanese Patent Publication No. 51-38753, Japanese Patent Publication No. 54-2408, etc. can be used. The carboxy-modified polyvinyl alcohol according to the present invention has excellent emulsifying power and emulsion stability, and has a 6%
At a moderate concentration, it exhibits emulsifying power and emulsion stability equivalent to 8 to 10% polyvinyl alcohol, and can fully fulfill its role as a protective colloid. In addition, the self-coloring pressure-sensitive recording sheet using the microcapsule liquid obtained using the carboxy-modified polyvinyl alcohol according to the present invention has high coloring ability because there is no decrease in the activity of the color developer. Even if the amount is reduced by about 10%, it is possible to obtain the same color development as when polyvinyl alcohol is used, so it is possible to reduce the amount of coating and reduce costs. Furthermore, when using the microliquid obtained using the carboxy-modified polyvinyl alcohol according to the present invention, a curtain coating method can be used for coating, making simultaneous multilayer coating, sequential multilayer coating, and high-speed coating possible, reducing costs. This method has the great advantage of not only reducing the size of the paper, but also producing a self-coloring pressure-sensitive recording sheet with excellent surface smoothness. In the present invention, a color former is one that has the property of donating electrons or accepting protons such as acids to develop color, and is not particularly limited, but specific compounds of these color formers include:
As triarylmethane compounds, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, that is, crystal violet lactone, 3,3-bis(p-dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl) phthalide, -dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3- (p-dimethylaminophenyl)-3
-(2-phenylindol-3-yl)phthalide, 3,3-bis-(1,2-dimethylindol-3-yl)-5dimethylaminophthalide, 3,
3-bis(1,2-dimethylindol-3-yl)-6dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-bis -(2-phenylindol-3-yl)-5-dimethylaminophthalide, 3-p-dimethylaminophenyl-
3-(1-methylpyrrol-2-yl)-6-dimethyl-aminophthalide, etc.; as diphenylmethane compounds, 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halofenyl-leucoauramine, N- 2,4,5-trichlorophenylleucoolamine, etc.; as xanthene compounds, rhodamine B-anilinolactam,
Rhodamine Bp-nitroanilinolactam, Rhodamine B-p-chloroanilinolactam, 7-dimethylamino-2-methoxyfluorane, 7-diethylamino-2-methoxyfluorane, 7-diethylamino-3-methoxyfluorane, 7- diethylamino-3-chlorofluorane, 7-diethylamino-3-chloro-2-methylfluorane,
7-diethylamino-2,2-dimethylfluorane, 7-diethylamino-3-acetylmethylaminofluorane, 7-diethylamino-3'-methylaminofluorane, 3,7-diethylaminofluorane, 7-diethylamino-3- Dibenzylaminofluoran, 7-diethylamino-3-methylbenzylamino-fluoran, 7-diethylamino-3-chloroethylmethylaminofluorane, 7-diethylamino-3-diethylaminofluorane, etc.; As a thiazine compound, benzoylleucomethylene blue , p-nitrobenzylleucomethylene blue, etc.; as a spiro compound,
3-Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-
Examples include methoxy-benzo)-spiro-pyran, 3-propyl-spiro-dibenzopyran, and mixtures thereof. These color formers are dissolved in a solvent and encapsulated. As a solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil, kerosene, paraffin, naphthenic oil, alkylated biphenyl, alkylated terphel, chlorinated paraffin, alkylated naphthalene, and the like. The wall film-forming substances used in the present invention may be those that react with each other to produce water-insoluble and oil-insoluble polymeric substances. Examples of these compounds include polyisocyanates, polyisothiocyanates, polyamines, polycarbonates, etc. Compounds include acids, polybasic acid chlorides, acid anhydrides, epoxy compounds, polyols, acrylate compounds, polysulfides, lactones, and lactams. The wall-forming material may also be a prepolymer of the above compound. Additionally, polyamide resins such as polycondensates of aliphatic or aromatic polyamines and dicarboxylic acids are also useful in the present invention. Specific examples of wall film-forming substances used in the present invention include substances having isocyanate groups or isothiocyanate groups such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6 -tolylene diisocyanate, 2,
4-Tolylene diisocyanate, naphthalene-
1,4-diisocyanate, diphenylmethane
4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,
3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate,
4,4'-diphenylpropane diisocyanate,
Trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, ethyridine diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexyl diisocyanate Silene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-
Diisocyanate such as diisothiocyanate, ethyridine diisothiocyanate, diisothiocyanate, 4,4′,4″-triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate, poly Addition of triisocyanates such as methylene polyphenyl isocyanate, tetraisocyanates such as 4,4'-dimethyldiphenylmethane, 2,2',5,5'-tetraisocyanate, hexamethylene diisocyanate and hexanetriol. Adducts of 2,4-tolylene diisocyanate and brenz catechol, adducts of tolylene diisocyanate and hexanetriol, adducts of tolylene diisocyanate and trimethylolpropane, adducts of xylylene diisocyanate and trimethylolpropane There are polyisocyanate prepolymers such as adducts. Polyamines include aromatic polyamines such as o-phenylenediamine, p-phenylenediamine, 1,5-S-diaminonaphthalene, phthalamide, etc., NN'-S There are aliphatic polyamines such as -1,3-propylene diamine, NN'-S-1,4-butylene diamine, etc. Polycarboxylic acids include pimelic acid, superric acid, azelaic acid, sepatic acid, phthanic acid, and terephthane. Examples of polybasic acid chlorides include terephthalic acid chloride, 1,5-naphthoic acid chloride, 4,4'-biphenyl dicarboxylic acid, 4,4'-sulfonine dibenzoic acid, etc.
4'-biphenyl-dicarboxylic acid chloride, 4,
Examples include 4'-oxydibenzoic acid chloride. Examples of the acid anhydride include maleic anhydride, succinic anhydride, phthalic anhydride, and benzoic anhydride, which are dehydrated condensates of two carboxylic acid molecules or dicarboxylic acids. Examples of epoxy group-containing compounds include aliphatic glycidyl ethers such as diglycidyl ether, glycerin triglycidyl ether, and polyallyl glycidyl ether with a molecular weight of 150 to 5000, and aliphatic glycidyl esters such as diglycidyl ester of linoleic dimer acid. , aromatic glycidyl ethers such as diglycidyl ether of bisphenol-A, triglycidyl ether of trihydroxyphenylpropane, and tetraglycidyl ether of tetraphenylene ethane;
and 4,4-bis(4-hydroxyphenyl)
Glycidyl ether/ester mixtures such as diglycidyl ether ester of pentanoic acid may be mentioned. Examples of polyols include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, hydroxy polyalkylene ethers, and the like. The polyhydric alcohols used are, for example, catechol, resorcinol, hydroquinone, 1,2-
Dihydroxy-4-methylbenzene, 1,3-hydroxy-5-methylbenzene, 3,4-dihydroxy-1-methylbenzene, 3,5-dihydroxy-1-methylbenzene, 2,4-dihydroxyethylbenzene, 1,3 -naphthalene diol, 1,5-naphthalene diol, 2,7-naphthalene diol, 2,3-naphthalene diol,
o,o'-biphenol, p,p'-biphenol,
1,1'-bi-2-naphthol, bisphenol A, 2,2'-bis(4-hydroxyphenyl)butane, 2,2'-bis(4-hydroxyphenyl)
-isopentane, 1,1'-bis(4-hydroxyphenyl)-cyclopentane, 1,1'-bis(4-hydroxyphenyl)-cyclopentane, 1,1'-bis(4-hydroxyphenyl)-cyclopentane,
hydroxyphenyl)-cyclohexane, 2,
2'-bis(4hydroxy-3-methylphenyl)
Propane, bis-(2hydroxyphenyl)-methane, xylylene diol, ethylene glycol,
1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,
6-heptanediol, 1,7-heptanediol, 1,8-octanediol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, glycerin, and sorbitol, aromatic and aliphatic polyhydric alcohols or Derivatives of polyhydric phenols, such as the compounds described in "Dye to Yakuhaku" 24, 38-55 (1962), may also be used. The hydroxy polyesters used are, for example, those obtained from polycarboxylic acids and polyhydric alcohols. Examples of polycarboxylic acids for producing hydroxypolyester include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, isophthalic acid, terephthalic acid, and glyconic acid, and examples of polyhydric alcohols include those mentioned above. There is a kimono. Hydroxy polyalkylene ethers are, for example, condensation products of alkylene oxides and polyhydric alcohols. Examples of the alkylene oxide used to produce the hydroxy polyalkylene ether include ethylene oxide, propylene oxide, butylene oxide, or amylene oxide, and as the polyhydric alcohol, the compounds mentioned above are used. Of course, the hydroxy polyalkylene ethers used may be those synthesized from other starting materials such as tetrahydrofuran, epihalohydrins such as epichlorohydrin, and aralkylene oxides such as styrene oxide. Particularly useful hydroxy polyalkylene ethers are those prepared from highly lipophilic alkylene oxides having 3 to 6 carbon atoms, such as polypropylene oxide, condensation products of polybutylene oxide with glycols, glycerin, pentaerythritol and sorbitol. It is a certain polyether. Also useful are polyols which are continuous adducts of alkylene oxides based on alkylene diamines such as ethylene diamine or condensates of these polyhydric alcohols. For example, N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine;
N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine. Polyols include condensation products of thioglycols or reaction products of polyhydric alcohols with appropriate thioether glycols. Examples of acrylate compounds include α-methyl cyanoacrylate and α-cyanoacrylate.
-Propyl cyanoacrylate, butyl α-cyanoacrylate, and the like. Examples of polyester acrylates include dimethacrylate-bis(ethylene glycol) phthalate. Polysulfides include those obtained by the reaction of dihalides and sodium sulfide, such as Some have the structure of Examples of lactone and lactam compounds include bis-α-angelicalactone, ε-caprolactam, and η-capryllactam. Catalysts may be used to accelerate the reaction with the wall-forming material. Such catalysts include a wide variety of compounds, but some representative ones include, for example, when a compound containing an isocyanate group or an isothiocyanate group is used as a wall film-forming substance. , 1 trimethylamine, triethylamine, N-
Methylmorpholine, N-ethylmorpholine,
Tertiary amines such as N,N-dimethylethanolamine, triethanolamine, N,N',N'-tetrakisquis(2-hydroxypropylamine), triethylenediamine 2. Dibutyltin diacetate, dibutyltin dilaurylate. dibutyltin-laurate,
Dibutyltin maleate, dibutyltin laurate maleate, dibutyltin bis(6
- methylaminocaproate) 3 Tertiary phosphines such as trialkylphosphine, dialkylbenzylphosphine etc. 4 Stannous octoate, stannous oleate, lead octoate, cobalt naphthenate Known catalysts are used, such as salts of organic acids, such as, with various metals, such as tin, lead, cobalt, nickel and copper. The amount of wall-forming material is determined by the amount of nuclear material to be encapsulated and the desired wall thickness. The amount of catalyst used to promote the reaction between the first wall-forming material and the second wall-forming material is small, such as about 0.01 to 5% by weight based on the weight of the wall-forming material. . In the present invention, the color developer has the property of accepting electrons or donating protons, and is an adsorbent that develops color when it comes into contact with the color former described above. Includes those in which clay is used in combination with carboxylic acids, metal salts thereof, etc. Clays refer to acid clay, activated clay, atabalgide, zeolite, bentonite, kaolin, etc. Among these, clays with a three-layer structure, such as acid clay and activated clay, have high color developing ability.
preferable. In the present invention, it is most preferable to use acid clay. Phenolic resins are proton-releasing phenolic resins that are generally known in the art.
Specifically, they are phenolic aldehyde polymers (so-called novolac type) and phenolic acetylene polymers. Examples of these compounds include p-phenylphenol formaldehyde polymer, p-fluorophenol-formaldehyde polymer, p-chlorophenol-formaldehyde polymer, p-
Promophenol-formaldehyde polymer, p
- iodophenol-formaldehyde polymer,
p-nitrophenol formaldehyde polymer,
p-carboxyphenol-formaldehyde polymer, o-carboxyphenol-formaldehyde polymer, p-carbalkoxyphenols-formaldehyde polymer, p-aroylphenol-formaldehyde polymer, p-lower alkoxyphenol-formaldehyde polymer, p- −
Alkyl ( _C1 - _C12 ) phenols, such as p-methylphenol, p-ethylphenol, p-n
-propylphenol, p-isopropylphenol, p-n-amylphenol, p-isoamylphenol, p-cyclohexylphenol,
p-1,1-dimethyl-n-propylphenol, p-n-hexylphenol, p-isohexylphenol, p-1,1-dimethyl-n-butylphenol, p-1,2-dimethyl-n-butyl Phenol, p-n-hebutylphenol,
p-isobutylphenol, p-5,5-dimethyl-n-amylphenol, p-1,1-dimethyl-n-amylphenol, p-n-octylphenol, p-1,1,3,3-tetramethyl Butylphenol, p-isooctylphenol,
p-n-nonylphenol, p-isononylphenol, p-1,1,3,3-tetramethylamylphenol, p-n-decylphenol, p-
Isodecylphenol, p-n-undecylphenol, p-isoundecylphenol, p-n
-Dodecylphenol, an isomer of the p-alkylphenol (alkyl group has 1 to 12 carbon atoms), and a copolymer of formaldehyde with a mixture containing two or more of the alkylphenol and its isomer, etc. can be mentioned. Further, even if an m-substituent is added to the p-substituted phenol, it behaves in the same manner, and the addition of an m-substituent is not important. Here, the aromatic carboxylic acid in the polyvalent metal salt of aromatic carboxylic acid used in the present invention includes those represented by the general formula. general formula

[Formula] [In the formula, R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ are each a hydrogen atom, a halogen atom, a hydroxy group, an amino group, an alkylamino group, a nitro group, an aldehyde group, an alkyl group, a cyclo Represents a group having about 18 or less carbon atoms, such as an alkyl group, an aryl group, an alkylaryl group, an aralkyl group, and an alkoxy group.
R ₁ , R ₂ or R ₃ , R ₄ may be ring-closed with each other to form a five- or six-membered ring. ] Among the compounds of the above general formula, particularly useful compounds are:
R ₁ is a hydroxy group, and at least one of the o- and p-positions of the hydroxy group is substituted with an alkyl group, an aryl group, an aralkyl group, or the like. Specific examples of aromatic carboxylic acids include 2,4-
dichlorobenzoic acid, p-isopropylbenzoic acid,
2,5-dinitrobenzoic acid, pt-butylbenzoic acid, N-phenylanthranilic acid, 4-methyl-3-nitrobenzoic acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 3,5
-dinitrosalicylic acid, 5-t-butylsalicylic acid, 3-phenylsalicylic acid, 3-methyl-5-
t-butylsalicylic acid, 3,5-di-tert-amylsalicylic acid, 3-cyclohexylsalicylic acid,
5-cyclohexylsalicylic acid, 3-methyl-5
-isoamylsalicylic acid, 5-isoamylsalicylic acid, 3,5-di-sec-butylsalicylic acid, 5
-nonylsalicylic acid, 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-5-t-butylbenzoic acid, 2,4-cresotic acid, 5,5-methylenedisalicylic acid, acetaminobenzoic acid (om
p), 2,4-dihydroxybenzoic acid, 2,5-
Dihydroxybenzoic acid, anacardic acid, 1-naphthoic acid, 2-naphthoic acid, 1-hydroxy-2-
naphthoic acid, 2-hydroxy-3-naphthoic acid,
3,5-dicyclohexylsalicylic acid, 3,5-
Di-t-butylsalicylic acid, 3,5-di-t-octylsalicylic acid, 2-hydroxy-naphthoic acid, thiosalicylic acid, etc., and compounds obtained by adding olefins having about 4 to 18 carbon atoms, styrene derivatives, etc. to these compounds. There is. Specifically, 3,5-di(α-methylbenzyl)salicylic acid, 3-(α-methylbenzyl)-5
-(α,α-dimethylbenzyl)salicylic acid, 3
-(4′-α′,α′-dimethylbenzyl)phenyl-
5-(α,α-dimethylbenzyl)salicylic acid,
3-cyclohexyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-phenyl-5-(α,
Examples include α-dimethylbenzyl)salicylic acid and 3,5-di(α,α-dimethylbenzyl)salicylic acid. Among these, 3,5-
Di(α-methylbenzyl)salicylic acid, 3-(α
-methylbenzyl)-5-(α,α-dimethylbenzyl)salicylic acid, 3-(4′-α′,α′-dimethylbenzyl)phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5- Di-t-butylsalicylic acid, 3,5-di-t-octylsalicylic acid, 3-cyclohexyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-phenyl-5-
(α,α-dimethylbenzyl)salicylic acid, 3,
Examples include 5-di(α,α-dimethylbenzyl)salicylic acid and 3,5-dicyclohexylsalicylic acid. In addition, the polyvalent metals for making metal salts with the above-mentioned aromatic carboxylic acids include magnesium, aluminum, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper,
Zinc, potassium, germanium, strontium, yttrium, zirconium, molybdenum,
silver, cadmium, indium, tin, antimony,
Examples include barium, tungsten, lead, and bismuth. Among these metals, those that are particularly effective are zinc, tin, aluminum, magnesium,
Calcium, etc. The most effective of these is zinc. Moreover, two or more types of the above color developers can also be used in combination. In the present invention, a coating liquid containing a color developer as a main component is a liquid in which a color developer is dissolved or dispersed together with a color developer binder in water or other solvent, and usually about 10%
It refers to something prepared to a solid content concentration of ~60wt%. As the color developer binder, latex binders such as acrylic ester latex, vinyl acetate latex, and styrene-butadiene latex are generally used. In particular, styrene-butadiene latex with an average degree of polymerization of 500 to 100,000 is used. Preferably, the amount used is 5 parts by weight or more, preferably 10 to 30 parts by weight, per 100 parts by weight of the color developer. Further, when a latex binder is used, other water-soluble binders can also be used together, and the combination can improve the film surface strength, the dispersibility of the color developer, and the like. Water-soluble binders used in combination include proteins (e.g., gelatin, albumin, casein, etc.), cellulose (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, etc.),
Water-soluble natural polymer compounds such as sutucarose (e.g. agar, sodium alginate, carboxymethyl starch, gum arabic, etc.); water-soluble polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, and other latexes. used. In this case, the amount used is based on 100 parts by weight of the color developer.
It is preferable to use 20 parts by weight or less, and the total amount of the binder is preferably 40 parts by weight or less. If it is more than 40 parts by weight, the color developing ability decreases and it is also undesirable in terms of cost. Water is most commonly used as a solvent for dissolving or dispersing the color developer and the color developer binder, but organic solvents such as methyl ethyl ketone, ethyl acetate, benzene, and toluene are also used. The web used in the present invention includes commonly used wood-free paper, intermediate paper, coated paper, machine-coated paper, art paper, cast-coated paper, synthetic paper, mazin-coated paper, plastic film, and the like. In the present invention, the coating amount of the coating liquid containing microcapsules as three components is suitably 4 g/m ² or more, preferably 5 to 8 g/m ² on a dry weight basis. In addition, the amount of coating liquid containing a color developer as a main component varies depending on the type of color developer used, and for clays it is 4 g/
m ² or more, preferably 5 to 8 g/m ² is appropriate;
When phenolic resin, aromatic carboxylic acid and its metal salt are used together with clay, 0.5g/m ²
As mentioned above, 0.8 to 8 g/m ² is preferable. Examples and comparative examples are listed below to further clarify the effects of the present invention. Capsule liquid A and capsule liquid B used in the following examples were prepared as follows. As wall film-forming substances, 5 parts of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane and 1 part of an adduct of sorbitol and propylene oxide are dissolved in 4 parts of ethyl acetate, and this is dissolved in diisopyropropane. To 28 parts of pilnaphthalene,
It was dissolved in an oily liquid containing 1 part of crystal violet lactone and 1 part of benzoylleucomethylene blue. (This is referred to as oil-based liquid A.) To prepare the protective colloid, dissolve 1.5 parts of carboxy-modified polyvinyl alcohol with a saponification degree of 85 mol% and a polymerization degree of 1725, which is obtained by modifying 5 mol% of polyvinyl alcohol with itaconic acid, in 20 parts of water. The liquid temperature was 20°C. (Protective colloid A) For encapsulation, oily liquid A is gradually added to vigorously stirring protective colloid A to form an o/ω type emulsion with an average oil drop size of 8 μm.
After adding more water and adjusting the concentration to 30%,
The liquid temperature is raised to 75℃ to promote the formation of a wall film.
After holding for 30 minutes, it was cooled to 25°C to obtain capsule liquid A. In addition, instead of protective colloid A, protective colloid B was used, in which 1.5 parts of carboxy-modified polyvinyl alcohol with a saponification degree of 80 mol% and a polymerization degree of 1725, which was obtained by modifying 3 mol% of polyvinyl alcohol with acrylic acid, was dissolved in 20 parts of water. In other respects, capsule liquid B was obtained in the same manner as capsule liquid A. In addition, capsule liquid C used in the following comparative examples
was prepared as follows. saponification degree of 88 mol% instead of protective colloid A,
Capsule liquid C was obtained in the same manner as capsule liquid A except that protective colloid C was prepared by dissolving 1.5 parts of polyvinyl alcohol with a degree of polymerization of 550 in 20 parts of water. Color developer liquid A and color developer liquid B used in the following examples and comparative examples were prepared as follows. Color developer solution A was prepared by dissolving 7 parts of 50% sodium hydroxide in 200 parts of water, gradually adding 80 parts of acid clay while stirring vigorously, and then adding 19 parts of styrene-butadiene rubber latex and dodecylbenzenesulfonate. Obtained by adding 0.1 part of acid amine salt. Color developer liquid B was obtained by adding 3 parts of zinc 3,5-di(α-methylbenzyl)salicylate and 7 parts of water to 306.1 parts of color developer liquid A with vigorous stirring. In the following Examples and Comparative Examples, the capsule liquid and the color developer liquid were applied by a curtain coating method, and the coating amounts were 4 g/m ² for the capsule liquid and 6 g/m ² for the color developer liquid. Example 1 Capsule liquid A was placed on paper with a width of 300 mm and a basis weight of 50 g/ ^m2 .
A multilayer curtain consisting of the color developer solution A and the color developer solution A is formed.
Coating was carried out at a coating speed of 300 m/min so that the capsule layer was the lower layer to obtain self-coloring pressure-sensitive recording sheet sample #1. The sample #1 obtained in this way is placed in a pressurizing device.
The color was developed by applying a pressure of 400 Kg/cm ² , and the color density on the first day was measured using a spectrophotometer at a wavelength of 610 nm. Table 1 shows the results. Comparative Example 1 Self-coloring pressure-sensitive recording sheet sample #2 was obtained in the same manner as in Example 1 except that capsule liquid C was used instead of capsule liquid A. Sample #2 thus obtained was colored in exactly the same manner as in Example 1, and the color density was measured. Table 1 shows the results.

[Table] From Table 1, it was found that sample #1 according to the present invention had significantly higher color density than sample #2. Example 2 Self-coloring pressure-sensitive recording sheet sample #3 was obtained in exactly the same manner as in Example 1, except that the developer layer was applied as the lower layer. Sample #3 thus obtained was colored in exactly the same manner as in Example 1, and the color density was measured. Table 2 shows the results. Comparative Example 2 Self-coloring pressure-sensitive recording sheet sample #4 was obtained in the same manner as in Example 2 except that capsule liquid C was used instead of capsule liquid A. Sample #4 thus obtained was colored in exactly the same manner as in Example 1, and the color density was measured. Table 2 shows the results.

[Table] From Table 2, it was found that sample #3 according to the present invention had significantly higher color density than sample #4. Example 3 Capsule liquid A and color developer liquid A were mixed to form a single-layer curtain, which was applied to the same paper as in Example 1 to obtain self-coloring pressure-sensitive recording sheet sample #5. Sample #5 thus obtained was colored in exactly the same manner as in Example 1, and the color density was measured. Table 3 shows the results. Comparative Example 3 Self-coloring pressure-sensitive recording sheet sample #6 was obtained in exactly the same manner as in Example 3 using capsule liquid C instead of capsule liquid A. Sample #6 thus obtained was colored in exactly the same manner as in Example 1, and the color density was measured. Table 3 shows the results.

[Table] From Table 3, it was found that sample #5 according to the present invention had significantly higher color density than sample #6. Example 4 Self-coloring pressure-sensitive recording sheet samples #7, #8, #9 were prepared in exactly the same manner as in Examples 1, 2, and 3 using capsule liquid B instead of capsule liquid A.
I got it. Each sample #7, #8, #9 obtained in this way
For this, the color was developed in exactly the same manner as in Example 1,
Table 4 shows the results of measuring the color density.

[Table] From Table 4, sample #7 according to the present invention,
#8 and #9 are samples #2, #4, and #6, respectively
It was confirmed that the color development density was significantly higher than that of the previous one. Example 5 Self-coloring pressure-sensitive recording sheet samples #10, #11, and #12 were obtained in exactly the same manner as in Examples 1, 2, and 3 using developer solution B instead of developer solution A. Ta. Each sample #10, #11, #12 obtained in this way
For this, the color was developed in exactly the same manner as in Example 1,
Table 5 shows the results of measuring the color density. Comparative Example 4 Self-coloring pressure-sensitive recording sheet samples #13, #14, and #15 were obtained in exactly the same manner as in Comparative Examples 1, 2, and 3, using developer solution B instead of developer solution A. Ta. Each sample #13, #14, #15 obtained in this way
For this, the color was developed in exactly the same manner as in Example 1,
Table 5 shows the results of measuring the color density.

【table】

[Table] In Table 5, when comparing samples #10 and #13, #11 and #14, and #12 and #15, it is found that according to the present invention, self-coloring pressure-sensitive recording with significantly high color density It turned out that the sheet was obtained.

Claims (1)

[Claims] 1. In a method for producing a self-coloring pressure-sensitive recording sheet, in which microcapsules containing a color former and a layer containing a color developer that develops a color when in contact with the color former are coated on the same surface of a support. , when encapsulating an oily liquid in which a color former is dissolved by an interfacial polymerization method or an internal polymerization method, the oily liquid is emulsified and dispersed in the presence of carboxy-modified polyvinyl alcohol to form a synthetic polymer wall. A method for producing a self-coloring pressure-sensitive recording sheet.