JPS647597B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pressure-sensitive recording copy sheet. More specifically, the present invention relates to a pressure-sensitive recording copying sheet that utilizes a color-forming reaction between a nearly colorless color former and a color developer, which is an adsorbed or reactive compound that develops color upon contact with the color former. Conventionally, color formers are substances that donate electrons or accept protons such as acids to develop color, and color developers are substances that accept electrons or donate protons, such as acid clay and activated clay. , attapulgite, zeolite, bentonite, clay materials such as kaolin, salicylic acid,
Pressure-sensitive recording materials that utilize coloring reactions with organic acids such as tannic acid, gallic acid, and phenolic compounds, or their metal salts, and acidic polymers such as phenol-formaldehyde resins are well known, for example, as disclosed in US Pat. No. 2,505,470. No. 2505489, same
No. 2550471, No. 2548366, No. 2712507, No.
No. 2730456, No. 2730457, No. 3418250, JP-A-Sho
It is described in No. 49-28411, Japanese Unexamined Patent Publication No. 50-44009, etc. The color forming agent layer of pressure-sensitive copying paper is prepared by dissolving the color forming agent in a solvent, dispersing it in a binder or containing it in microcapsules, and then applying it to a support such as paper, plastic film, resin-coated paper, etc. Obtained by coating. On the other hand, the color developer is dissolved or dispersed together with a binder in a medium such as water and applied to a support to obtain a color developer sheet. Generally, the color former and developer are applied to the same or opposite or different sides of the support. Then, the coloring agent in the microcapsules is released by writing pressure or hitting pressure, and develops color when it comes into contact with the color developer.
Records can be obtained according to pressure. As mentioned above, various color developers are known for use in pressure-sensitive recording materials. However, when clays, such as activated clay and acid clay, which are currently widely used as color developers, are used, they have disadvantages such as poor light resistance or water resistance of the coloring material, and poor stability over time. . Organic color developers are known as color developers that do not have these drawbacks. A color developer sheet using an organic color developer is prepared by mechanically dispersing the color developer in water together with an inorganic pigment, a binder, a dispersant, and other additives, and applying the resulting coating liquid onto a support. is common, but
No. 54-143322 describes a method of preparing a color developer sheet by dissolving an organic color developer in an organic solvent with a boiling point of 150°C to 310°C and emulsifying this in water and applying a coating liquid to a support. Are listed. The pressure-sensitive recording copying sheet using the color developer sheet obtained by this method has the advantage that the color developer reacts efficiently with the color forming agent and exhibits excellent color development with the use of a small amount of color developer. However, when used in combination with color-forming agent-containing capsules prepared using the commonly used gelatin coacervate method, color fogging (water immersion coloring) may occur when water gets on the product, or when stored under high humidity. It has drawbacks such as a tendency to self-color. Therefore, an object of the present invention is to obtain a copying sheet for pressure-sensitive recording which exhibits excellent color development using a small amount of color developer and which does not have the above-mentioned drawbacks. The objects of the present invention are a sheet coated with a coating solution containing a proton-donating or electron-accepting color developer, and a coated surface of the sheet coated with capsules containing a color former that reacts with the color developer to produce color. In a pressure-sensitive recording copying sheet in which the color developer is combined with
The capsule contains a water emulsion of an organic color developer dissolved in an organic solvent having a boiling point of This was achieved using a pressure-sensitive recording copying sheet with special characteristics. As the organic color developer used in the present invention, aromatic carboxylic acids and metal salts thereof, and phenolic resins are preferable. Examples of these aromatic carboxylic acids and their metal salts include those described in Japanese Patent Publication No. 10856/1983. Specific examples of these aromatic carboxylic acids are:
Benzoic acid chlorobenzoic acid (o, m, p), nitrobenzoic acid (o, m, p), toluic acid (o, m,
p), 4-methyl-3-nitrobenzoic acid, 2-chloro-4-nitrobenzoic acid, 2,3-dichlorobenzoic acid, 2,4-dichlorobenzoic acid, p-isopropylbenzoic acid, 2,5-dinitro benzoic 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, 3-methyl-5-tert-butylsalicylic acid,
3,5-di-tert-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
-tert-butylbenzoic acid, 2,4-cresotic acid, 5,5-methylenedisalicylic acid, acetaminobenzoic acid (o, m, p), 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, anacardo acid, 1-naphthoic acid, 3,5-di-α,
α-Dimethylbenzylsalicylic acid, 3,5-di-
α-Methylbenzylsalicylic acid, 2-naphthoic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-
Examples include naphthoic acid, thiosalicylic acid, and 2-carboxybenzaldehyde. Examples of metals forming metal salts with the aromatic carboxylic acids include copper, lead, magnesium, calcium, zinc, aluminum, tin, and nickel. Furthermore, as phenolic resins,
Phenol formaldehyde resin, phenol acetaldehyde resin, and phenol acetylene resin are known as so-called novolak type phenolic resins as shown in No. 20144. For example, p-alkylphenols such as p-cresol, p-ethylphenol, p-butylphenol, p-cyclohexylphenol, p-octylphenol, p-nonylphenol, allylphenols such as p-phenylphenol, Polycondensation resins of aralkylphenols such as α-naphthylphenol, β-naphthylphenol, cumylphenol, and benzylphenol, halogenated phenols such as p-chlorophenol, and formaldehyde or acetaldehyde, and zinc, manganese, etc. Examples include so-called metal salt-modified phenolic resins modified with. Two or more types of these color developers can also be used. The solvent used in the present invention has a boiling point of 150°C to 310°C.
℃, and preferably an organic solvent that further dissolves 10% or more of the organic color developer. Examples include aliphatic or aromatic esters, biphenyl derivatives, naphthalene derivatives, biphenyl alkanes, and the like. Specifically, methyl amyl acetate (1,3-dimethylbutyl acetate), 2-ethyl butyl acetate, 2-ethylhexyl acetate, amyl propionate, n
-butyl butyrate, iso-butyl-iso-butyrate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 2,4-dimethyl-2,4-pentanediol diacetate, 2,2-dimethyl-1,3
-butanediol diisobutyrate, 2-methyl-2,4-pentanediol dipropionate,
2,3,3,4-tetramethyl-2,4-pentanediol monoacetate, amyl lactate,
2-methylbiphenyl, 3-methylbiphenyl, 3,3-dimethylbiphenyl, 2,4-dimethylbiphenyl, 2,6-dimethylbiphenyl, 2,4,6-trimethylbiphenyl Neil, cyclohexylbenzene, bicyclohexylbenzene, monoisopropyl biphenyl, monoisopropylnaphthalene, diisopropylnaphthalene,
Examples include methylphenylxylylmethane. These solvents can also be used in combination with a poor solvent such as a petroleum distillate having a boiling point of 150°C to 310°C as a diluent. If a solvent with a boiling point of 150° C. or lower is used in the present invention, evaporation will be significant during the coating or papermaking process, resulting in poor workability. On the other hand, a solvent with a boiling point of 310°C or higher is not advantageous because it is difficult to evaporate during the drying process after coating or papermaking. That is, if the solvent remains in the coated liquid paper, the color developing ability, the resistance of the color former, etc. will be impaired. The organic color developer is dissolved in the above solvent from 5 to 70%, preferably from 10 to 50%. This organic solvent solution is emulsified in water using a stirrer or the like to form a coating liquid. The organic solvent solution is added to water in an amount of 5 to 100%, preferably 30 to 80%, and emulsified. In this case, adding an ionic or nonionic surfactant water-soluble polymer has the advantage that a stable emulsion can be prepared in a short time. Furthermore, when preparing a coating solution, inorganic pigments such as titanium oxide, zinc oxide, silicon oxide, calcium oxide, calcium carbonate, aluminum hydroxide, kaolin, talc, barium sulfate, etc. can be used in combination to improve coating suitability, hiding power, and color developing ability. The desired combined use amount for obtaining desired effects such as improvement of the oil content is 1 to 1000 parts, more preferably 2 to 50 parts, based on the oil-soluble acidic substance. A binder is added to the coating liquid thus obtained, and the coating liquid is applied to a support. These binders include those generally known in the art, such as latexes such as styrene-butadiene copolymer latex, polyvinyl alcohol, maleic anhydride-styrene copolymer,
Starch, casein, gum arabic, gelatin,
Synthetic or natural polymeric substances such as carboxymethyl cellulose and methyl cellulose can be used. The final amount of organic developer applied to the support is
0.1g/ ^m2 to 3.0g/ ^m2 , preferably 0.2g/ ^m2 ,
1.0 g/m ² is suitable. The color former that reacts with the color developer used in the recording copy sheet of the present invention is not particularly limited, but specific compounds of these color formers include (1) 3,3-triarylmethane compounds; Bis(p-
dimethylaminophenyl)-6-dimethylaminophthalide (i.e. crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-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)-5-dimethylaminophthalide, 3,
3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 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.; (2) Diphenylmethane compounds such as 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leucoauramine, N-2,4,5-trichlorophenylene enylleukoolamine, etc. (3) As xanthene compounds, rhodamine B-anilinolactam, rhodamine B-p nitroanilinolactam,
Rhodamine B-p-chloroanilinolactam, 2
-dimethylamino-7-methoxyfluorane, 2
-diethylamino-7-methoxyfluorane, 3
-diethylamino-7-methoxyfluorane, 3
-diethylamino-7-chlorofluorane, 2-
Diethylamine-3-chloro-7-methylfluorane, 7-diethylamino-2,2-dimethylfluorane, 7-diethylamino-3-acetylmethylaminofluorane, 7-diethylamino-
3'-Methylaminofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3,
7-diethylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-methylbenzylamino-fluorane, 3-diethylamino-7-chloroethylmethylaminofluorane, 3-diethylamino-
7-diethylaminofluorane, etc.; (4) Thiazine compounds, such as benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc.; (5) Spiro compounds, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran , 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiro-pyran, 3-propyl-spiro-
Examples include dibenzopyran and mixtures thereof. The coloring agent is dissolved in a solvent, encapsulated, and applied to a support according to a conventional method. 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 terphenyl, alkylated naphthalene, diarylethane, triarylmethane, chlorinated veraphine, and the like. As the main membrane material of the capsule, melamine-formaldehyde resin or urea-formaldehyde resin is used. In carrying out the present invention, a water-soluble binder or a latex-based binder is generally used to prepare a coating solution containing capsules containing a color former. Furthermore, capsule protectants conventionally used in the production of pressure-sensitive recording copy sheets, such as
Cellulose powder, starch particles, talc, etc. are also used. Furthermore, a dispersant and an antifoaming agent may be added. The pressure-sensitive recording copy sheet of the present invention provides significantly superior color development compared to conventional pressure-sensitive recording copy sheets, and furthermore, fogging when attached to water and under high humidity is significantly improved. The pressure-sensitive recording sheet of the present invention can also be obtained as a medium sheet in which a color developer-containing coating solution and a color former-containing capsule coating solution are coated on opposite sides of the same support. The pressure-sensitive recording copying sheet of the present invention will be specifically explained below with reference to Examples, but the invention is not limited to these Examples. Example (1) Preparation of color developer sheet (sample No. 1) 10 parts of zinc 3-5-di-α-methylbenzylsalicylate was mixed with 2,2,4-trimethyl-1,3-
20 parts of pentanediol diisobutyrate plus
The mixture was heated and dissolved at 90°C. This was added to 50 parts of a 2% polyvinyl alcohol (PVA-205 manufactured by Kuraray) aqueous solution, and 0.1 part of a 10% sodium sulfosuccinate aqueous solution was added as a surfactant, using a homogenizer to adjust the emulsion to an average particle size of 3μ. An emulsion was prepared. Next, 80 parts of aluminum hydroxide, 20 parts of zinc oxide
1 part sodium hexametalate and 200 parts water
After preparing a dispersion liquid using a Keddy mill and mixing the above emulsion, further as a binder,
100 parts of 10% PVA-110 (manufactured by Kuraray) aqueous solution and 10 parts (as solid content) of carboxy-modified SBR latex (SN-304, manufactured by Sumitomo Nogatux) were added, and water was added to adjust the solid content concentration to 20%. . This coating solution was applied to a 50 g/m ² base paper using an air knife coater so that the solid content was 5.5 g/m ² and dried. ) was obtained. (2) Preparation of color developer sheet (sample No. 2) P, P, P resin (manufactured by Sumitomo Duress), para-phenylphenol, formaldehyde resin instead of zinc 3,5-di-α-methylbenzylsalicylate ) to obtain a color developer sheet (hereinafter referred to as sample No. 2) used in the present invention in the same manner as in Example 1. (3) Preparation of color developer sheet for comparison (sample No. 3) 10 parts of zinc 3,5-di-α-methylbenzylsalcylate, 80 parts of aluminum hydroxide, zinc oxide
20 parts, 1 part sodium hexametaphosphate and water
200 parts were used and uniformly dispersed using an attritor. Add 10% PVA-110 (manufactured by Kuraray) to the resulting dispersion.
100 parts of an aqueous solution and 10 parts (as solid content) of carboxy-modified SBR latex (SN-304 manufactured by Sumitomo Nogatux) were added, and water was added to adjust the solid content concentration to 20%. This coating solution was applied to 50 g/m ² of base paper. A color developer sheet (hereinafter referred to as sample No. 3) was obtained by coating and drying using an air knife eater so that a solid content of 5.5 g/m ² was applied to the surface of the sample. (4) Preparation of coloring agent-containing capsule sheet (sample) Partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by National Starch Co., Ltd., VERSA,
TL500, average molecular weight 500,000) was added to 95 parts of hot water at about 80°C with stirring and dissolved. Dissolve in approximately 30 minutes and then cool. The pH of the aqueous solution is 2-3
A 20% by weight aqueous sodium hydroxide solution was added to this to adjust the pH to 4.0. Separately, 100 parts of diisopropylnaphthalene in which 2.5% crystal violet lactone and 1.0% benzoyl leucomethylene blue were dissolved was added to a 5% aqueous solution of a portion of the sodium salt of the polyvinylbenzenesulfonic acid.
It was emulsified and dispersed in 100 parts to obtain an emulsion having a particle size of 4.5μ in average diameter. Separately, 6 parts of melamine,
11 parts of a 37% by weight formaldehyde aqueous solution and 30 parts of water were heated and stirred at 60°C, and after 30 minutes, a transparent mixed aqueous solution of melamine, formaldehyde and melamine-formaldehyde initial condensate was obtained. The pH of this mixed aqueous solution was 6-8. Hereinafter, this mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate will be referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to and mixed with the above emulsion, and the pH was adjusted to 6.0 with a 3.6% by weight hydrochloric acid solution while stirring.
The liquid temperature was raised to 65°C and stirring was continued for 360 minutes. This capsule liquid was cooled to room temperature and adjusted to pH 9.0 with 20% by weight sodium hydroxide. 200 parts of a 10% by weight polyvinyl alcohol aqueous solution and starch particles for this capsule dispersion.
A coating solution of microcapsule dispersion was prepared by adding 50 parts and adding water to adjust the solid diameter concentration to 20%. This coating solution was applied to a 50 g/m ² base paper using an air knife coater so that the solid content was 5 g/m ² and dried to obtain a coloring agent-containing capsule sheet (hereinafter referred to as sample) used in the present invention. Obtained. (5) Preparation of color former-containing capsule sheet (sample) Isoban-10 (molecular weight 160,000 to 170,000, 1:1 molar ratio copolymer of isobutylene and maleic anhydride, manufactured by Kuraray) was mixed with water to a neutralization degree of 0.8. A 10% aqueous solution was prepared by heating and dissolving using sodium oxide. To 100 parts of a 1:1 mixed aqueous solution of 10% aqueous solution of isoban-10 and 10% aqueous gum arabic solution, 10 parts of urea, 1 part of resorcinol, and 55 parts of water were added and dissolved with stirring. Thereafter, the pH of the system was adjusted to 3.5 using 5N hydrochloric acid. 100 parts of diisopropyl naphthalene in which 2.5% crystal violet lactone and 1.0% benzoyl leucomethylene blue were dissolved was added to the above aqueous solution with vigorous stirring and emulsified to form an o/w emulsion, with an average oil droplet size of 4.5. Stirring was stopped when the temperature reached μ. To this emulsion were added 6 parts of a 10% by weight aqueous solution of ammonium chloride. While stirring, 27 parts of a 37% formaldehyde aqueous solution was added to adjust the temperature of the system to 65°C. Thereafter, the temperature was maintained at that temperature for 2 hours while stirring, and then the temperature was lowered to 25° C., and the pH of the system was adjusted to 9.0 using a 20% aqueous sodium hydroxide solution to obtain a color former oil-containing capsule dispersion. 200 parts of a 10% by weight polyvinyl alcohol aqueous solution and starch particles for this capsule dispersion.
A coating liquid of microcapsule dispersion liquid was prepared by adding 50 parts and adjusting the solid content concentration to 20% by adding water. This coating solution was applied to 50 g/m ² base paper using an air knife coater so that the solid content was 5 g/m ² and dried to obtain a color former-containing capsule sheet (hereinafter referred to as sample) used in the present invention. Obtained. (6) Capsule sheet containing coloring agent for comparison (sample)
Preparation: 20 parts of acid-treated gelatin having an isoelectric point of 8.0 and 20 parts of gum arabic were dissolved in 120 parts of water at 40°C, 0.4 parts of sodium alkylbenzenesulfonate was added as an emulsifier, and 2.5% of crystal violet lactone and 200 parts of diisopropylnaphthalene in which 1.0% benzoyl leucomethylene blue was dissolved was added with vigorous stirring to emulsify the emulsification, and when the emulsification reached 4.5μ, 200 parts of water at 40°C was added to suppress the progress of emulsification. While continuing to stir, add another 420 parts of water at 30°C.
The pH of the system was adjusted to 4.4 by adding 20% hydrochloric acid.
The liquid was further cooled to 8°C while stirring, and then 1.5 parts of 20% glutaraldehyde was added. Subsequently, 60 parts of a 10% carboxymethyl cellulose aqueous solution was poured, and then a 25% sodium hydroxide solution was added dropwise to adjust the pH to 8.5, and the liquid temperature was heated to 30° C. to obtain microcapsules with hardened walls.
To this capsule dispersion, 200 parts of a 10% polyvinyl alcohol aqueous solution and 50 parts of starch particles were added, and water was added to adjust the solid content concentration to 20% to prepare a coating liquid of the microcapsule dispersion. This coating solution was applied to 50 g/m ² base paper using an air knife coater so that the solid content was 5 g/m ² and dried to obtain a coloring agent-containing capsule sheet (hereinafter referred to as sample) to be used for comparison. Ta. (7) Performance comparison The color developer sheets and color former-containing capsule sheets obtained as above were combined to make pressure-sensitive recording copy sheets as shown in Table 1, and the performance of each combination was evaluated. compared. Each color developer sheet and color former-containing capsule sheet were placed facing each other, and the color development and fog (water immersion color development, moisture fog resistance) were compared with respect to the following items, and the results are shown in Table 1. (a) Color-forming property A capsule sheet containing a color-forming agent was layered on a color-developing agent sheet, and color was developed under a static pressure of 150 Kg/m ² . After 1 hour, the color density was measured using a Beckman DB spectrophotometer (610 mμ). (b) Water immersion color development The color developer sheet immersed in water and the capsule sheet containing the color former were layered and air-dried, and the fog density on the surface of the color former containing capsules was measured using a Beckman DB spectrophotometer. (c) Moisture-resistant fogging A developer sheet and a capsule sheet containing a color former are layered and a pressure of 100 g/cm ² is applied at 50°C relative humidity.
The fogging of the color developer sheet after being left under 90% high humidity for 24 hours was visually evaluated.

[Table] From the above results, it can be seen that remarkable effects can be obtained by the present invention.

Claims (1)

[Claims] 1. A sheet coated with a coating liquid containing a proton-donating or electron-accepting color developer;
In a pressure-sensitive recording copying sheet in which the coated surfaces of sheets coated with capsules containing a color forming agent that reacts with the color developing agent are opposed to each other, the coating liquid containing the color developing agent is heated at 150°C. The capsule contains an aqueous emulsion of an organic color developer dissolved in an organic solvent having a boiling point of from A copy sheet for pressure-sensitive recording, which is characterized by: