DE2513468C2 - Method of making a color developer - Google Patents

Description

(D

wherein Ri, R2, R3, R4 and R5, which may be the same or different, represent a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, an aldehyde group, an alkyl group, a cycloalkyl group, an aryl group, an alkaryl group, an aralkyl group, an alkoxy group or an aryloxy group and R ₁ , R 2, R3, R4 and R5 can be combined at adjacent positions to form a ring, or dimers of the formula (I) in which at least one of the radicals Ri, R2, R3, R4 and R5 is from a methylene group or a chain can be used.

6. The method according to claim 5, characterized in that the aromatic carboxylic acid is an acid according to formula (II)

(II)

wherein Ri, R2, R3, R4 and R5 have the same meaning as in claim 5, are used.

7. The method according to claim 1 to 6, characterized in that a water-soluble metal salt Chloride, a sulfate, a nitrate or an acetate of a metal from groups 1 B, U A, II B, III A, IV A, Vl B, VII B or VIII of the periodic table is used.

8. The method according to claim 7, characterized in that a chloride, a water-soluble metal salt Sulphate, a nitrate or acetate of zinc, tin, aluminum, magnesium or calcium is used.

9. The method according to claim 1 to 8, characterized in that the reaction at a pH of 6 until 13 is carried out.

10. The method according to claim 1 to 9, characterized in that the clay in an amount of 0.1 to 100 Parts by weight per 100 parts by weight of the alkali salt of the aromatic carboxylic acid is used.

11. The method according to claim 1 to 10, characterized in that the water-insoluble aluminum compound in an amount of 0.5 parts by weight or more per 100 parts by weight of the alkali salt of aromatic carboxylic acid is used.

The invention relates to a method for producing a color developer. In particular, the invention relates to a process for the preparation of a color developer which reacts with a color former so that the Color formation is caused.

Recording webs are well known which take advantage of the color forming reaction which occurs

when a practically colorless electron-donating organic compound, such as malachite green lactone, benzoyl leucomethylene blue, Crystal violet lactone, rhodamine B-lactam, a 3-dialkylamino-7-dialkylaminofluoran, 3-methyl-2,2-spirobi- (benzo [f] chromene) and the like, hereinafter referred to as color formers, is contacted with an electron attractive material, hereinafter referred to as color developer.

Illustrative examples of such recording webs are pressure-sensitive copier papers such as them

I 1

for example in US patents 25 05 470, 25 05 489, 25 50 471, 25 48 366, 27 12 507, 27 30 456, 27 30 457, 34 18 250 and the like. Are described, and heat-sensitive recording materials such as, for example Japanese Patent Publication 4160/1968 and U.S. Patent No. 29 39 009 and the like. and similar materials. In addition, a reproducing method is known, wherein a a color former containing printing ink by a device, for example a pencil, on a Developer-coated sheet is transferred, as described in DE-OS 19 39 624 and the like. Described.

In many cases, the coloring reaction is caused by the application of a physical action such as Pressure, heat and the like using a pen, typewriter or the like. Caused

The most typical examples of such recording webs are pressure-sensitive copier papers. A pressure sensitive one Copy paper is made by dissolving a color former in a solvent, dispersing the obtained solution in a binder or encapsulation of the obtained solution and then peeling up the The resulting coating solution on a carrier, such as paper, synthetic resin films, with synthetic Resin-coated papers and the like manufactured-

A heat-sensitive recording sheet is made by drawing up a color former in combination with a heat-fusible material, e.g. acetanilide, made on a support in this case the heat-fusible material consists of a material which melts when heated and the color image ■ ner solves

On the other hand, a color former is used in water or an organic solvent in combination with dissolved or dispersed in a binder and is absorbed onto or impregnated in the support. The color developer can be drawn up or impregnated as a mass before recording.

In general, color formers and color developers are placed on the same side or both sides of the support or mounted on different carriers.

A solid acid is generally used as such a color developer, and clays such as acid clay, active clay, Attapulgite, zeolite, bentonite and the like, organic; acids such as succinic acid, tannic acid, gallic acid, phenol compounds and the like. And acidic polymers such as phenolic resins, e.g. B. phenol formaldehyde resins and phenol acetylene resins and the like are known for this.

In particular, phenolic resins have received public attention as color developers as in Japanese Patent Publication 20 144/1967, and numerous improvements have been suggested, such as for example, in US Pat.

Phenolic resins are excellent in that the color image formed is not affected when mixed with water is contacted, however, the developability of the phenol resin is insufficient and the light resistance is insufficient of the formed color image is bad. For example, that of a phenolic resin and crystal violet lactone fades obtained color image easily when left under normal room lighting are silent when the picture is exposed to sunlight, and the surface of the phenolic resin that is not was included when the color was formed changes to yellow. Furthermore, other acidic polymers are, for example Maleic acid-rosin resins or partially or fully hydrolyzed styrene-maleic anhydride copolymers unsuitable in practice in that their developability is inherently low

Metal compounds of aromatic carboxylic acids have already been found to be effective as color developers for Proposed recording tracks. By using metal compounds of aromatic carboxylic acids namely, the properties of the color developer are significantly improved. However are development eligibility and the film strength of the coated layer is insufficient depending on the manufacture of the developer coating solution, and additional improvements are needed.

For example, DE-OS 21 52 765 describes a metal salt of aromatic carboxylic acid as a color developer, which by reacting an alkali salt of the aromatic acid with a water-soluble metal salt will be produced. Furthermore, it is only an indication of the possibility of using sound in one such a system included. DE-PS 8 78 806 only describes that aluminum oxide and aluminum phosphate can be used as acceptors, but there is no suggestion that these compounds should be used together with a color developer.

The object of the invention is a method for producing a color developer which has a possesses improved developing property and film strength.

The inventive method for producing a color developer is characterized in that a Alkali salt of an aromatic carboxylic acid and a water-soluble metal salt in the presence of clay and a water-insoluble aluminum compound are implemented.

According to the invention, the specific effect is obtained that the use of the water-insoluble aluminum compound an increase in the viscosity of the coating solution due to the common use of the Metal salt of an aromatic carboxylic acid and clay prevented.

As described above, a metal compound of an aromatic carboxylic acid, by itself Color development suitability Desitzt can be used, and therefore such a compound can also be used as Color developer can be used even if it is used individually. But if one is the metal salt containing coating solution is prepared, the viscosity of the coating solution increases, and so on metal compounds are formed with a large particle size (100 μm or more), so that the suitability for color development and the film strength of the color developing layer finally formed is insufficient will.

The coating solution containing the metal compound of an aromatic carboxylic acid becomes general by reacting at least one alkali salt of an aromatic carboxylic acid and a water-soluble one Made of metal salt. If at this time a clay, such as an acid clay, active clay, bentonite, attapulgite and the like. Is added to the system and reacted, the size of the particles of the metal compound of the

aromatic carboxylic acid, so that a coating solution which has high color developing suitability and provides good film quality can be obtained. However, the viscosity of the coating solution is high, and the coating properties are quite poor

On the other hand, if there is a water-insoluble aluminum compound in combination with a clay, if that The alkali salt of the aromatic carboxylic acid and the water-soluble metal salt are reacted, increase Color developing suitability and film strength compared with when clay is used alone, and further the viscosity is low and the coating properties are improved

The term "water-insoluble aluminum compound" here denotes those aluminum compounds which are soluble in water in a ratio of 10 -g or less to 100 g of water (from 2G ⁰ C),

ίο for example aluminum oxide, aluminum hydroxide, aluminum phosphate, magnesium aluminate, cobalt aluminate unddyi.

The term "clay" used here in combination with the water-insoluble aluminum compound includes the generally known clays such as acid clays, active clays, bentonite, attapulgite, kaolin, agaltomite, Diatomaceous earth and the like and those clays which have an aromatic compound absorption index of 25 or less, for example, acid clays, acid clays treated with a weak acid, bentonite and the like, which are preferred. Clays with an absorption index for aromatic compounds of 25 or less show a tendency to increase the viscosity of the system in the production of the metal compound of the aromatic Increasing carboxylic acid, however, also decreases if a water-insoluble aluminum compound the viscosity of the system drops significantly. The adsorption index for aromatic compounds is shown in measured in the following way.

The clay is pulverized and passed through a sieve with a sieve opening of approximately 0.044 mm and the clay thus sieved is placed in a weighing bottle and dried in a thermostat at 150 ± 5 ° C for 3 hours. After drying, the clay is placed in a desiccator ( Desiccant: CaCl ₂ ) brought and left to stand at room temperature to form the sample. 1 g of the sample is weighed exactly and placed in a centrifugal test tube (volume 10 ml). 2 ml of a mixed solvent of anhydrous toluene and anhydrous isooctane (volume 30:70) is added to the centrifugal test tube and the test tube is plugged. The test tube is then shaken while gently holding the stopper down to disperse the sample well. The test tube is then tightly capped and attached to a shaker that vibrates 100 times per minute and shaken at room temperature (20 to 30 ° C.) for 40 minutes. After shaking, the test tube is centrifuged at 3500 rpm for 2 minutes to separate off the supernatant solution. The refractive index of the original solution and the supernatant solution are measured at 20 ° C and the values obtained are used to calculate the adsorption index of the aromatic compound according to the following relationship:

Adsorption index of the aromatic compound

= (Refractive index of mixed solvents made of toluene and isooctane)
- (refractive index of the supernatant solution)

The aromatic carboxylic acids to be used here include those acids corresponding to the following Formula (I)

COOH
R,

■ ■ (D

wherein Ri, R2, R3, R ₄ and R5, which may be the same or different, each represent a hydrogen atom, a hydroxy atom, a halogen atom, e.g. B. a chlorine atom or a bromine atom, a nitro group, a formyl group, an alkyl group, e.g. B. having 1 to 20 carbon atoms, preferably 2 to 12 carbon atoms, for example unsubstituted alkyl groups such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a tert-butyl group, n-amyl group, a tert-amyl group, a nonyl group and the like. Or substituted alkyl groups substituted with substituents such as halogen atoms, e.g. B. chlorine or bromine, —CHO groups, —NO2 groups, —OH groups and the like are substituted, a cycloalkyl group, for example with 5 to 10 carbon atoms, e.g. B. a cyclohexyl group, an aryl group, e.g. B. a phenyl group, a naphthyl group, which may be unsubstituted or with a halogen atom, e.g. B. chlorine or bromine, a formyl group, a nitro group or hydroxyl group and the like. Can be substituted, an alkaryl group which, for. B. contains the above-mentioned alkyl and aryl groups as portions thereof and in which the alkyl portion comprises 1 to 10 carbon atoms, an aralkyl group, for example with the above-mentioned alkyl and aryl groups as units thereof, in which the alkyl portion can contain 1 to 10 carbon atoms, an alkoxy group, for example with 1 to 20 carbon atoms, preferably 2 to 12 carbon atoms, both

for example a methoxy group, an ethoxy group, a tert-butoxy group, a nonyloxy group and the like., or an aryloxy group, for example a phenoxy group, and R 1, R 2, R 3, R 4 and R 5 on adjacent ones Positions forming a ring, for example a 5- or 6-membered saturated or unsaturated one Ring, such as B. a benzene ring, a cyclohexyl ring and the like. May be combined. Dimers of acids

corresponding to the formula (I), in which at least one of the radicals Ri to Rs is a methylene group or a die is a chain connecting both benzene rings of the formula (I) to one another, are likewise suitable.

Of the acids corresponding to the formula (I), those acids corresponding to the following formula (II) are as well as dimers thereof particularly useful according to the invention:

(II)

wherein Ri, R ₂ , R ₃ and R _{4 have} the same meaning as above.

Illustrative examples of alkali salts of aromatic carboxylic acids are sodium salts, potassium salts, lithium salts, Cesium salts and the like.

Illustrative examples of such aromatic carboxylic acids of the formula (I) are benzoic acid and chlorobenzoic acid (o-, m- and p-isomers), nitrobenzoic acid (o-, m- and p-isomers), toluic acid (o-, m- and p-isomers), 4-methyl-3-nitrobenzoic acid, 2-chloro-4-nitrobenzoic acid, 2,3-dichlorobenzoic acid, 2,4-dichlorobenzoic acid, p-isopropylbenzoic acid, 2,5-dinitrobenzoic acid, p-tert-butylbenzoic acid, N-phenylanthranilic acid, 4-methyl-3-nitrobenzoic acid, Salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 3,5-dinitrosalicylic acid, 5-tert-butylsalicylic acid, 3-phenylsalicylic acid, S-methyl-S-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-di-tert-amylsalicylic acid, 3-cyclohexylsalicylic acid, 3-cyclohexylsalicylic acid, S-methyl-S-isoamylsalicylic acid, 5-isoamylsalicylic acid, 3,5-di-sec-butylsalicylic acid, 5-nonylsalicylic acid, 2-hydroxy-3-methylbenzoic acid, 2-Hydroxy-5-tert-butylbenzoic acid, 2,4-cresotic acid, 5,5-methylenedisalicylic acid, acetaminosalicylic acid (o-, m- and p-isomers), 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, anacardic acid, 2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, thiosalicylic acid, 2-carboxybenzaldehyde and similar compounds.

On the other hand, the "water-soluble metal salts", i. H. with solubilities of 1 g or more in 100 g Water at 25 ° C, which react with the above-described alkali metal salts of aromatic carboxylic acids which Chlorides, sulfates, nitrates, acetates and the like of metals of group I B of the periodic table, such as copper, silver and the like. Group II A metals such as magnesium, calcium, Group II B metals such as zinc, cadmium, Mercury, Group III A metals such as aluminum, gallium, Group IV A metals such as tin, lead, Group VI B metals such as chromium, molybdenum, Group VII B metals such as manganese, and metals of Group VIII such as cobalt, nickel. Of these metal salts, particularly effective metal salts are the chlorides, which Sulphates and the nitrates of zinc, tin, aluminum, magnesium and calcium.

The color developer according to the invention can be easily prepared by stirring a mixture of the alkali salt of a aromatic carboxylic acid and the water-soluble metal compound in the presence of clay and the water-insoluble Aluminum compound can be obtained. Therefore, the reaction conditions are not always marriage limited specific reaction conditions. However, the pH of the system is preferably in Range from 6 to 13, particularly preferably from 8 to 11, since the viscosity is further reduced. It is enough according to the invention that clay and water-insoluble aluminum compound are simply in combination, so that the order of addition is not limited. Any additional order can be used will. _.

The alkali metal salt of the aromatic carboxylic acid and the water-soluble metal salt are present in equimolar amounts at temperatures from 0 to 100 ° C, preferably 10 to 50 ⁰ C over a period of 1 lake up to 1 hour. Reacted, however, each thereof may be in excess . The amount of the clay used is 0.1 to 100 parts by weight, preferably 2 to 50 parts by weight per 100 parts by weight of the alkali salt of the aromatic carboxylic acid, and the amount of the water-insoluble aluminum compound used is 0.5 part by weight or more, for example 0.5 to 200 parts by weight, especially 1 to 100 parts by weight per 100 parts by weight of the alkali salt of the aromatic carboxylic acid.

In this way, the topcoat solutions of the color developer can be obtained, and to the topcoat solution If desired, a water-soluble or water-dispersible binder can be added. Suitable examples of such binders include natural polymer compounds such as proteins, e.g. B. gelatin, Gum arabic, albumin, casein and the like, celluloses, e.g. B. carboxymethyl cellulose, hydroxyethyl cellulose and the like. Saccharides, e.g. B. agar, sodium alginate, starch, carboxymethyl starch and the like. And synthetic polymer compounds, such as polyvinyl alcohol, polyvinyl pyrrolidone, polymers of maleic acid, e.g. B. styrene-maleic acid polymers, Methyl vinyl ether maleic acid polymers, modified with natural resins or rosin Maleic acid polymers, acrylic acid polymers, e.g. B. polyacrylic acid, polyacrylic acid-acrylamide polymers and the like. In addition, examples of water-dispersible binders include latexes and emulsions with water as Dispersants. For example, latexes, e.g. B. styrene-butadiene-based latexes, butadiene-acrylonitrile-based latexes, Chloroprene-based latexes, vinyl acetate-based latexes, acrylic-based latexes, latexes Vinyl chloride base and the like made by emulsion polymerization and polybutadiene emulsions, Polyisoprene emulsions, butyl rubber emulsions and the like obtained by dispersing an ionic polymerization polymers prepared in solution were obtained, for example in water using a Solvent and an emulsifier can be used. The binder is generally used in an amount of 5 up to 50 parts by weight to 100 parts by weight of the coating solution (solids content).

Solution can be an acidic resin such as a phenol-formaldehyde resin, for example in a ratio of 10 to 1000 parts by weight to 100 parts by weight of the metal salt, an inorganic pigment such as a metal oxide, metal hydroxide or a chemically or physically treated derivative thereof, for example in a ratio of 10 to 1000 parts by weight per 100 parts by weight of the metal salt are added.
The coating solution is coated over either the entire surface or selected parts of the surface of a support such as synthetic resin films, synthetic resin-coated paper, synthetic paper and the like so that the amount of the metal compound of aromatic carboxylic acid is 0.1 g / m ² or more, preferably 0.5 to 2 g / m ^{2 of} the support. The upper limit of the absorbed amount is determined mainly from an economic point of view, so that the effect of the invention is achieved even above the above range.

The color developer according to the invention has the property that it causes the color to be formed, when it comes into contact with an electron-donating colorless compound, so that it is responsible for different Recording tracks can be used. The present invention will be described in detail below explained with reference to the most typical recording sheet, namely a pressure-sensitive copier paper.

The microcapsules used in pressure-sensitive copier papers can be easily converted using the well known methods. Since the concentration of the color former slightly in the dissolution of the color former for the production of the microcapsules can be determined, the production of the invention is

The size of the microcapsules used is not limited in any way. Microencapsulation Processes Applicable According to the Invention include the coacervation process as described in U.S. Patents 2,800,457, 2,800,458, 3,041,289, 36 87 865, an interfacial polymerization process as described in US Patents 34 92 380, 35 77 515 and British patents 9 50 443.10 46 409.10 91 141, an internal polymerization process, as in British patent specification 12 37 498, French patent specification 20 60 818, 20 90 862, an external polymerization process as described in British Patent 9 89 264, the Japanese Patent Publications 12 380/1962, 14 327/1962, 29 483/1970, 7313/1971, 30 282/1971 described

The solvents to be used for the dissolution of the color former are by no means within the scope of the invention and a wide variety of these can be used. All so far known solvents can be used, and for example aromatic synthetic oils, such as alkylated naphthalenes, alkylated biphenyls, hydrogenated terphenyls, alkylated diphenylmethanes, where in in each case the number of carbon atoms in the alkyl group is 1 to 5 and the number of alkyl groups is 1 to 4, petroleum fractions such as kerosene, naphtha, paraffin oils, aliphatic synthetic oils such as chlorinated Paraffin, vegetable oils such as cottonseed oil, soybean oil, linseed oil and mixtures thereof can be used. The concentration of the color former solution is not particularly limited, so that it is for every person skilled in the art is easy. Microcapsules using concentrations of 1 to 10% of the color former solution as they are are generally used for the production of conventional pressure-sensitive copier papers.

The color images used here are a colorless compound that becomes colored when in contact with a ,

Color developer, like a solid acid, and can also be used as an electron donating colorless Designate organic compounds as color formers. The color developer according to the invention is in none Way limited by the type, properties and the like of the color former. Thus, all types of color formers can be used. For example, triacryl methane compounds, diaryl methane compounds, Xan-

then compounds, thiazine compounds, spiropyran compounds can be used. >

Illustrative examples of such color formers are given below: ^L.

Typical examples of the triphenylmethane compounds are 3,3-bis (p-dimethylaminophenyl) _-6-t dirnethylami-

no-phthalide, d. H.

Crystal violet lactone,

3,3-bis (p-dimethylaminophenyl) phthalide,

3- (p-Dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide,

3- (p-DimethyIaminophenyI) -3- (2-methylindol-3-yl) -phthalide, »

3- (p-Dimethylaminophenyl) -3- (2-phenylindol-3-yl) -phthalide,

3,3-bis- (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide,

33-bis- (1,2-dimethylindol-3-yl) -dimethylaminophthalide,

3,3-bis- (9-ethylcarbazo! -3-y) -5-dimethylaminophthalide,

33-bis- (2-phenylindol-3-yl) -5-dimethylaminophthalide,
3-p-Dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide

and similar materials.

Examples of diphenylmethane compounds are

t 4,4-bis-dimethylaminobenzhydrin benzyl ether, g

N-halophenylleucauramine, p

N-2,4,5-trichlorophenylleucauramine,

and similar connections. Q

I.

Suitable examples of xanthene compounds are ^

Rhodamine B-anilinoiactam, -r

Rhodamine (p-nitroanilino) lactam,
Rhodamine B- (p-chloroanilino) -lactam,
T-dimethylamino ^ -methoxyfluorane,
7-diethylamino-2-methoxyfluorane,

Z-diethylamino-S-chloro ^ -methoxyfluorane, 7-diethylamino-3- (acetylmethylamino) -fluorane,
7-diethylamino-3- (dibenzylamino) -fluorane,
7-DiethyIamino-3- (methylbenzylamino) -fluorane,
7-diethyiamino-3- (chloroethylmethy! Amino) -fluorane,

7-diethylamino-3- (diethylamino) fluorane and similar compounds.
Illustrative examples of thiazine compounds are
Benzoylleucomethylene blue,
p-nitrobenzyl leucomethylene blue
and similar connections. .

Illustrative examples of spiro-based compounds are

3-methyl-spiro-denaphthopyran,

3-ethyl-spiro-dinaphthopyran,

3,3'-dichloro-spiro-dinaphthopyran, 3-benzyl-spirodinaphthopyran,

3-methyl-naphtho- (3-methoxy-benzo) spiropyran,

3-propyl-spiro-dibenzodipyran

and similar connections.

The color formers listed above can be used individually or as mixtures of two or more will.

In this way, the microcapsule coating solution can be obtained. The microcapsules are preferred single-core, however, the object according to the invention can also be achieved with the use of multi-core microcapsules can be achieved. The size of the microcapsules is generally in the order of 1 to 500 μπι, preferably 2 to 50 μm. According to the invention, microcapsules of the same size can be used.

The microcapsule coating solution can be coated on a carrier as it is because the solution is generally a capsule dispersion in a solution. Furthermore, with or without separation of the microcapsules from the microcapsule dispersion in the solution, a binder, for example a latex, e.g. B. a styrene-butadiene rubber latex and the like., A water-soluble polymer compound such as starch, carboxymethyl cellulose. Polyvinyl alcohol, gum arabic, casein, gelatin and the like. And the like materials are added to the coating composition and peeled off. Furthermore, to the capsule coating solution or the capsule layer a capsule strengthening agent, for example fine cellulose powder according to US Pat. No. 2,711,375, a fine polymer powder according to US Pat. No. 3,625,736, a fine starch powder according to British Pat contain no color former as indicated in British Patent 12 35 991 and similar materials are added. The capsule reinforcing agent is preferably not present in layer form, but rather is dispersed in the capsule layer or on the surface thereof. The suitable amount of coating on the microcapsules is 1 to 10 g (as color former) per m ^{2 of} the carrier.

The carriers listed above include synthetic resin films coated with synthetic resins Papers, synthetic papers and the like. The microcapsule layer is on at least one side of the support and on or under the color developer layer, as indicated below, or on the surface of the support drawn up opposite to the color developer layer.

Conditions such as the kind, amount, additional method and form of those to be added to the color developing layer Additives or kind, shape and the like of the color former to be colored in combination with the color developer or Kind of the solvent and the like can be selected according to the usual recording web method.

According to the method of the invention, a color developer coating solution which is uniform and comprises fine particles prepared in the presence of a clay and the water-insoluble aluminum compound so that a sufficiently high developability can be obtained with a thin coating layer can. Therefore, when the color former is contacted with the color developer, the color developer can become a Provide high density color image instantly. Furthermore, the particles of the color developer are small and uniform 0.5 to 20 μm), the surface of the coating layer has excellent smoothness and is strong Film strength, so that a color developer excellent in reproducing properties can be obtained.

Furthermore, in the course of the preparation of the color developer, the viscosity of the coating solution does not become increased, so that it is possible to improve the coating properties. Therefore, the winding up of the Color developer is advantageous at the same time as papermaking, and furthermore, an air paint coating process becomes simple. These advantages, as well as the thin coating layer, help reduce the cost of the Product at.

The invention is illustrated in detail by means of the following examples. In each example, the effect is shown according to the invention by a color former containing by the preparation of a microcapsules in investigated the following manner and mounting the obtained microcapsules on a support-made layer was, and an under paper was made by mounting the color developer according to the invention on a Carrier made

The microcapsules containing the color former can be produced by various known processes However, in the present case, they were obtained by the method according to US Pat. No. 2,800,457 in manufactured in the following way. Unless otherwise indicated, all are parts, percentages, ratios and the like. Based on weight.

In 400 parts of water at 4O ⁰ C, 10 parts of acid-treated pigskin gelatin and 10 g of gum arabic were dissolved. To the resulting solution, 0.2 part of Turkish red oil was added as an emulsifier, and 40 parts of a color-forming oil was emulsified and dispersed therein. The color former oil was made by dissolving 3% crystal violet lactone in dissopropylnaphthalene. When the size of the oil droplets averaged 5 μm, the emulsification was stopped. Water of 40 ⁰ C was added to the volume of the

ίο Bring system to 900 parts and stirring continued. At this point in time, care was taken ^{to keep the solution temperature at 40 °} C. or higher. Then, a 10% acetic acid aqueous solution was added to adjust the pH of the solution to 4.0 to 4.2 for coacervation. The stirring was continued, and after 20 minutes the solution was cooled with ice water to gel the coacervate film deposited around the oil droplets. When the solution temperature was 20 ^° C., 7 parts of an aqueous 37% strength formaldehyde solution were added. If the temperature was 10 ^° C., 40 parts of a 7% strength sodium carboxymethyl cellulose solution were added, and then a 15% strength aqueous sodium hydroxide solution was added to adjust the pH to 9. The solution was then heated for 20 min with continued stirring in order to increase ^{the solution temperature to 50 ° C.} The microcapsule dispersion obtained in this way was set to 30 ^° C., and then the solution was drawn up on a paper of 40 g / m ² and dried so that a coating amount (solids content) of 5 g / m ^{2 was} obtained. The capsule webs were thereby preserved.

example 1

To 19.8 parts of water, 5 parts of acid clay (adsorption index for aromatic compound 14) and 1 part of the aluminum compounds shown in Table I were added, and the mixture was dispersed. Then a 10% aqueous sodium hydroxide solution was added with stirring to adjust the pH of the system to 10.5. In addition, 6 parts of a 10% strength aqueous gelatin solution were added, and a ^{solution prepared by dissolving 0.56 part of zinc chloride in 8 parts of water at 80 °} C. was gradually added. Then, 2 parts of 3,5-di-tert-butylsalicylic acid was dissolved in 0.32 part of sodium hydroxide and 20 parts of water, and the resulting solution was gradually added to the above system for reaction. 6 parts of a styrene-butadiene copolymer latex (solids content 48%), hereinafter referred to as SBR latex) were added to the dispersion obtained in order to prepare the coating solution. This coating solution was drawn up on an original paper of 50 g / m ² using a coating stick to give a solid content of 4 g / m ² .

Example 2

5 parts of the same acidic clay as in Example 1 and 0.25 part of aluminum oxide were added to 16.4 parts of water, and the mixture was dispersed. An 18% aqueous sodium hydroxide solution was then added with stirring to adjust the pH of the system to 10.5, and then 6 parts of a 10% aqueous gelatin solution and one by dissolving 0.56 part of zinc chloride in 8 parts Water from a ^{solution prepared at 80 °} C. was gradually added. Then, 2 parts were dissolved 3,5-di-tert-butylsalieylsäure in an aqueous solution of 032 parts of sodium hydroxide and 20 parts of water at 80 ⁰ C and the resulting solution was gradually added to the reaction. 6 parts of SBR latex were added to the dispersion obtained in this way

added to prepare the coating solution. This coating solution was coated using a coating bar onto an original paper of 40 g / m ² to form a solid content of 4 g / m ^2.

Comparative example 1

The procedure of Example 1 was repeated, except that water was used in an amount of 15.3 parts used and the aluminum compounds were not used, so a developer sheet for comparison was obtained.

Example 3

The procedure of Example 1 was repeated, but using active clay (adsorption index for aromatic Compounds 20) was used instead of the acidic clay according to Example 1, so that the developer web was obtained.

Comparative example 2

The procedure of Example 1 was repeated except that water was used in an amount of 15.3 parts, the same active clay as in Example 2 was used in place of the acidic clay of Example 1 and the aluminum compounds were not used, so that a developer sheet for Comparison was obtained.
B is ρ ie 1 4

The procedure of Example 1 was repeated, but using bentonite instead of the acidic clay of Example 1 was used to prepare the developer sheet.

Comparative example 3

The procedure of Example 1 was repeated, except that water in an amount of 15.3 parts was used, bentonite was used instead of the acidic clay of Example 1 and the aluminum compounds were not used, so that a developer sheet for comparison was obtained.

Example 5

5 parts of the same acidic clay as in Example 1 and 1 part of aluminum hydroxide were added to 23.6 parts of water, and the mixture was dispersed. An 18% aqueous sodium hydroxide solution was added with stirring to adjust the pH of the system to 10.5. 6 parts of an aqueous 10% gelatin solution was added, and a solution prepared by dissolving 1.4 parts of aluminum sulfate in 8 parts of water was gradually added with continued stirring. Then, 2 parts of 3,5-di-tert-butylsalicylic acid was dissolved in an aqueous solution 0.32 part of sodium hydroxide and 20 parts of water were dissolved with heating, and the resulting solution was gradually added to react. To the dispersion solution thus obtained, 6 parts of SBR latex were added to prepare the coating solution. This coating solution was applied to an original paper of 50 g / m ² with a coating stick to give a solids content of 4 g / m ² .

Comparative example 4

The procedure of Example 5 was repeated, except that 19.1 parts of water were used was used and the aluminum hydroxide was not used, so a developer sheet for comparison was obtained.

Example 6

The procedure of Example 5 was repeated, except that water in an amount of 22.1 parts 3,5-di-tert-butylsalicylic acid was used in an amount of 1.67 parts and alumina was used in place of aluminum hydroxide, so that a developing sheet was obtained.

Comparative example 5

The procedure of Example 6 was repeated, but using water in an amount of 17.6 parts was used and the alumina was not used, so a developer sheet for comparison was obtained.

Comparative example 6

In 8 parts of water, 0.56 part of zinc chloride was dissolved by heating. 2 parts of 3,5-di-tert-butylsalicylic acid was dissolved in an aqueous solution of 0.32 part of sodium hydroxide and 20 parts of water with heating, and the resulting solution was gradually added to the above aqueous zinc chloride solution with stirring. To the dispersion solution thus obtained, 2.2 parts of SBR latex was added to prepare a coating solution. This coating solution was drawn up on an original paper of 50 g / m ² with a coating stick to give a solid content of 1.5 g / m ² .

45 Comparative Example 7

6 parts of alumina were added to 19.8 parts of water. An 18% aqueous solution of sodium hydroxide was added with stirring to adjust the pH of the system to 10.5, and then were 6 parts of a 10% aqueous gelatin solution were added. Then became one by dissolving 0.56 parts Zinc chloride in 8 parts of water was gradually added to the solution prepared under heating.

A solution prepared by dissolving 2 parts of 3,5-di-tert-butylsalicylic acid in an aqueous solution of 0.32 part of sodium hydroxide and 20 parts of water with heating was gradually added to the reaction. To the dispersion thus prepared, 6 parts of SBR latex was added to prepare the coating solution. This coating solution was drawn up on an original paper of 50 g / m ² with a coating stick to give a solid content of 6 g / m ² .

A microcapsule sheet was attached to each of the developer sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 3, and color formation was carried out by pressing the sheets under a load of 6000 N / cm ² .

After the sheets were left to stand in a dark place for 24 hours, the reflection spectra were obtained in the wavelength range from 380 to 700 Γημιη using a Beckmann DB spectrophotometer and the absorbance at the maximum absorbance is shown in Table 1 as the color density.

In the same way, the viscosity became that in Examples 1 to 4 and Comparative Examples 1 to 3 prepared coating solutions measured; the results are given in Table I. The determination was made using a BL viscometer (60 rpm).

Aromatic 25th water-soluble 13 468 volume viscosity Color density Table I. Carboxylic acid liches the waiter of crystal Example or Metal salt aluminum train solution violet lactone Comparison link (mPa - s) example no. 3,5-di-tert-butyl- Zinc chloride sour tone 5 0.95 salicylic acid Example 1 3,5-di-tert-butyl- Zinc chloride aluminum sour tone 21 1.05 salicylic acid oxide Example 1 3,5-di-tert-butyl- Zinc chloride aluminum sour tone 8th 0.99 salicylic acid hydroxide Example 1 3,5-di-tert-butyl- Zinc chloride aluminum sour tone 5.2 0.96 salicylic acid phosphate Example 2 3,5-di-tert-butyl- Zinc chloride aluminum sour tone 121 0.91 salicylic acid oxide Comp.- 3,5-di-tert-butyl- Zinc chloride - Active tone 4.8 0.90 Example 1 salicylic acid Example 3 3,5-di-tert-butyl- Zinc chloride aluminum Active tone 15.0 0.95 salicylic acid oxide Example 3 3,5-di-tert-butyl- Zinc chloride aluminum Active tone 7.0 0.92 salicylic acid hydroxide Example 3 3,5-di-tert-butyl- Zinc chloride aluminum Active tone 50.0 0.86 salicylic acid phosphate VergL- 3,5-di-tert-butyl- Zinc chloride - Bentonite 13.1 1.12 Example 2 salicylic acid Example 4 3,5-di-tert-butyl- Zinc chloride aluminum Bentonite 15th 1.04 salicylic acid oxide Example 4 3,5-di-tert-butyl- Zinc chloride aluminum Bentonite 125 0.88 salicylic acid phosphate Comp.- 3,5-di-tert-butyl- aluminum - sour tone 23 0.90 Example 3 salicylic acid sulfate Example 5 3,5-di-tert-butyI- aluminum aluminum sour tone 13.0 0.85 salicylic acid sulfate hydroxide Comp.- 3-phenylsalicylic acid aluminum - sour tone 6th 0.84 Example 4 sulfate Example 6 3-phenylsalicylic acid aluminum aluminum sour tone 127 0.81 sulfate oxide Comp.- 3,5-di-tert-butyl- Zinc chloride - - koagu 0.60 Example 5 salicylic acid lates Comp.- 3,5-di-tert-butyl- Zinc chloride - - 7.5 0.49 Example 6 salicylic acid Comp.- aluminum Example 7 oxide

It follows from the values of Table I that the objects can be achieved according to the invention, when the alkali salt of the aromatic carboxylic acid and the metal compound in the presence of clay and the water-insoluble aluminum compound are implemented.

That is, solutions that are formed without the use of clay and the water-insoluble aluminum compound coagulated and could not be used as a topcoat solution. Even when they are raised can be, the developer web obtained has a markedly low suitability for development and can cannot be used in technical practice. In addition, coagulates are present on the surface Appearance is poor and the reproduction properties are poor.

If the water-insoluble compound is absent, the development suitability is relatively high, but it is Viscosity on the order of about 120 cP so that the coating suitability is markedly low. if for example, such a highly viscous coating solution applied by the air spread coating method when the air draw becomes so high that the enrobing cannot be controlled.

If the water-insoluble aluminum compound is present alone, the viscosity is low, but it is Development suitability low so that practical use cannot be made.

Comparative example 8

If, in Example 1, acidic clay and alumina are added to the reaction mixture shortly before the addition of the SBR latex was added, the solution coagulated so that coating was very difficult.

K!

10

Comparative example 9

In Comparative Example 7, if the acidic clay was added just before the SBR latex was added, that was
Viscosity relatively low, & h. 43 mPa · s, but the color density was 0.60, i.e. h "the color density was for
practical use too low. 5

Comparative example 10

If in comparative example 1 the aluminum oxide was added shortly before the addition of the SBR latex,
the viscosity was 115 mPa.s and the color density was 0.90 so that it could be used if there was a suitable coating method.

Claims (5)

Patent claims: 1. A method for producing a color developer, characterized in that an alkali salt an aromatic carboxylic acid and a water-soluble metal salt in the presence of clay and a water-insoluble aluminum compound are implemented. 2. The method according to claim 1, characterized in that a water-insoluble aluminum compound having a solubility ^10-1 g is used or less in 100 g of water at 20 ° C. 3. The method according to claim 1 or 2, characterized in that the water-insoluble aluminum compound Aluminum oxide, aluminum hydroxide, aluminum phosphate, magnesium aluminate or cobalt aluminate be used. 4. The method according to claim 1 to 3, characterized in that the clay is an acidic clay, active clay, bentonite, Attapulgite, kaolin, agaltomite or diatomaceous earth is used. 5. The method according to claim 1 to 4, characterized in that the aromatic carboxylic acid is an acid according to formula (I) COOH R ₁