JPS61173984A - Components of developer for pressure-sensitive paper - Google Patents

Abstract

PURPOSE:To provide components of developer for pressure-sensitive paper having the high density and clearness of a formed image and a suppressed discoloring of an image and a background when the components are exposed to light. CONSTITUTION:The titled components contain composite materials of zinc silicate selected from a group of composite hemi-molfite-type solosilicate and composite willemite-type nesozinc silicate, and organic compounds containing the phenol hydroxyl group. Composite minerals of zinc silicate and organic compounds containing the phenol hydroxyl group are contained at a weight ratio of 60:40-98:2. Minerals of composite zinc silicate are of hemi-molfite-type or willemite-type crystal constitution. The composite hemi-molfite is solozinc silicate which is basically of a chemical constitution expressed by the formula Zn4Si2O7(OH)2 and of a columnar crystal. Organic compounds containing the phenol hydroxyl group represent aromatic oxycarboxyl acid or its metallic salts or phenol resin, specially novolak-type phenol resin.

Description

Detailed Description of the Invention Field of Industrial Use The present invention relates to a color developer composition for pressure-sensitive paper, and more specifically, it is capable of forming clear and high-density images upon contact with leuco dyes, etc. The present invention relates to a color developer composition for pressure-sensitive paper, which can significantly suppress discoloration of the formed image and background due to exposure to light.

Prior Art and Technical Problems of the Invention Conventionally, the combination of a leuco dye and a color developer made of an acidic substance has been widely used in various information recording applications, such as pressure-sensitive recording, heat-sensitive recording, electrophotographic recording, printing, etc. In particular, in the field of pressure-sensitive paper, a paper substrate with a layer of color developer on one side is used as a so-called stamp paper.

Color developers include organic ones such as various phenols, phenolic resins, zinc salicylate and its derivatives, and those made of inorganic solid acids such as silica, aluminum silicate, clay minerals or acid-treated products thereof. However, while inorganic solid acid-based products have excellent heat resistance, solvent resistance, printing and transcription properties, etc., they have defects in coloring performance and fading due to the effects of light, heat, and moisture. is recognized.

For example, a color developer made of amorphous silica gives a clear colored image when combined with a leuco dye, but the image formed has extremely poor lightfastness, and for example, even after 2 hours of weather-o-meter exposure. , the image density decreases to 50% or less.

Further, although aluminosilicate clay minerals or acid-treated products thereof have slightly better light resistance than amorphous silica, they tend to cause discoloration when images come into contact with water. Additionally, coatings using these clay minerals or their acid treatments tend to turn yellow when exposed to light, and this background discoloration can cause the formed image to appear greenish. The problem is that it causes discoloration.

On the other hand, organic color developers such as organic compounds containing phenolic hydroxyl groups lack properties as fillers, so in order to provide printing ink absorption and writing characteristics to pressure-sensitive paper receiving printing, After all, it is essential to use an inorganic filler. It is actually practiced to mix acid clay or its acid-treated product with an organic color developer as a filler and color developer, but in this case, it is also necessary to reduce the yellowing tendency of the background due to exposure. Despite the differences, it will be shown. Furthermore, when a filler that is inert to the leuco dye, such as kaolin or calcium carbonate, is added to the leuco dye, the density of the formed image is inevitably diluted to some extent. An object of the invention is to provide a color developer composition for pressure-sensitive paper, which is composed of a combination of an organic color developer and a specific inorganic filler, and which eliminates the above-mentioned drawbacks of conventional color developers.

Another object of the present invention is to provide a color developer composition for pressure-sensitive paper which has excellent density and sharpness of formed images, and which suppresses discoloration of the image and background upon exposure to light.

Still another object of the present invention is to provide a color developer composition for pressure-sensitive paper that has excellent workability in coating paper and drying properties.

According to the present invention, a synthetic zinc silicate mineral selected from the group consisting of synthetic hemimorphite zinc sorosilicate and synthetic willemite zinc nesosilicate, and a phenolic hydroxyl group-containing organic compound are contained. A color developer composition for pressure-sensitive paper having characteristics is provided.

In this composition, the synthetic zinc silicate mineral and the phenolic hydroxyl group-containing organic compound are mixed in a ratio of 60:40 to 98:2.
may be present in a weight ratio of

Preferred embodiments of the invention The present invention will be described in detail below with respect to its preferred embodiments.

The synthetic zinc silicate mineral used in the present invention is characterized by having a hemimorphite type and an IF'ilLemitt type crystal structure.

The synthetic hemimorphite according to the present invention is a solosilicate compound mainly having a chemical structure represented by the formula % (1).
・It is lead and is a columnar crystal.

FIG. 1 is an X-ray diffraction spectrum of the synthetic hemimorphite according to the present invention, and it is understood that this synthetic hemimorphite exhibits the X-ray diffraction pattern shown in Table 7 below.

Table 7 6.59 94 5.38 73 4.62 57 4.15 45 3.30 94 3.09 100 2.95 402.70
142.56
492.43
222.40
682.31~2.29 32
．． 25 32.21
72.19-2.1
8 222.07
52.02
111.98 2
1.86-1.85 81, 80
30 Synthetic willemite is zinc silicate whose main component is the composition represented by the formula % (2).

FIG. 2 is an X-ray diffraction spectrum of synthetic willemite according to the present invention, and this synthetic willemite exhibits the X-ray diffraction characteristics shown in Table 8 below.

Table 8 6.9B 17 4.35 9 4.10 40 4.03 46 3.49 89 3.2 (S 7 3.15 7 2.83 96 2.72 3 2.63 100 2.56~2 .43 18 2.32 47 2.28 5 '2.21 3 2.14 8 2.07 3 2.05 3 2.01 121.97
31.93
111, 86
381, 83 31.
81 3 The crystalline zinc silicate mineral used in the present invention has the above-mentioned hemimorphite and/or willemite as a living body, but within the condition that this crystal structure is maintained, for example, Si
Part of the St□ component and/or the ZnO component does not exceed 10 mol of At, 0. Components can be substituted. Naturally, this synthetic mineral includes hemimorphite alone, willemite alone, two or more of hemimorphite and willemite coexisting, or amorphous silicate together with the above-mentioned crystalline zinc silicate. There is no problem even if zinc and amorphous silicic acid coexist.

Hemimorphite type zinc silicate is generally stable at temperatures up to 700C, but at temperatures above the above temperature it undergoes a dehydration reaction and forms willemite.
It becomes a metamorphosis.

The hemimorphite type or willemite type synthetic zinc silicate mineral used in the present invention is characterized by having fine and uniform particle size and excellent pigment properties.

Furthermore, this synthetic mineral has a feature of large oil absorption despite its relatively low surface activity.

That is, the oil absorption amount of this synthetic mineral (JIS K 5101
) is 60 to 120 ml/IQOf, especially 70 to 11
Although it is in the range of 0 mj/10C1, its BET specific surface area is 80 m2/g or less, particularly 10 to 50 i/f.

In addition, the median diameter measured by centrifugal sedimentation is generally 0.5
It is in the range from 3μ to 3μ, especially from 1 to 2.5μ.

These synthetic zinc silicate minerals alone cannot be used as coloring agents for Roif pigments. However, as will be explained later, it has the unique property of significantly improving the density and sharpness of the formed image when combined with an organic color developer without adversely affecting photochromicity or photobleaching. The synthetic zinc silicate mineral included in the present invention can be used with active silicic acid, amorphous silica, or other easily reactive silica raw materials and zinc oxide, hydroxide, or under reaction conditions. and a compound capable of producing the oxide or hydroxide in a sufficient stoichiometric amount to obtain the above composition, by hydrothermal treatment.

As the activated silicic acid, activated silicic acid obtained by acid treatment of clay minerals is particularly advantageously used. That is, by using this activated silicic acid as a raw material, a zinc silicate mineral having excellent pigment properties, such as fine particle size and homogeneity, can be easily obtained.

The reason for this is that layered silica, which forms the basis of activated silicic acid or activated aluminosilicic acid, is easier to decompose into smaller silicic acid units than silica gel, which has a three-dimensional structure, and is a hemimorphite type. , it is thought that recombination to the willemite type will be easily carried out.

In the present invention, raw clay minerals include one or more of smectite group clay minerals, such as so-called montmorillonite group clay minerals such as acid clay, bentonite, subbentonite, and fuller's earth, and beidellite, sabonite, and nontronite. A combination of these is preferably used.

Clay minerals other than those mentioned above, such as kaolin group clay minerals such as kaolin and leucite, chain clay minerals such as attapulgite, sepiolite, and palygorskite, may also be used. For example, kaolin does not have reactivity with acids in its original state, but when it is calcined to form metakaolin, the reaction with acids is easily carried out.

Acid treatment of clay minerals is performed using X of the surface index [001] of clay minerals.
- the linear diffraction peaks virtually disappear and the product ALtO,
:SiO, the molar ratio is preferably in the range of 1:11 to 1:99. The acid treatment conditions can be based on conditions known per se. For example, as the acid, mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as benzenesulfonic acid, toluenesulfonic acid, and acetic acid are used, and mineral acids such as sulfuric acid are generally used. The method of contacting the clay mineral with the acid may be arbitrary, such as a slurry activation method in which clay and acid are brought into contact with each other in a slurry state, a granular activation method in which granulated clay and acid are brought into solid-liquid contact, and a clay method. A dry activation method or the like may be employed in which a mixture of the organic compound and the acid is reacted in a dry manner (within the granules), and then by-product salts are extracted. The amount of acid used is
Although it varies depending on the acid treatment conditions, Al and O in the product
It is sufficient that the molar ratio of 5:SiO falls within the above-mentioned range and that other basic components such as Fe, 051, vyo or alkali metals in the clay mineral are substantially removed. For example, in the dry activation method, acid treatment is performed using 0.3 to 1.5 equivalents, particularly 0.6 to 1.2 equivalents, of acid or acid aqueous solution relative to the basic component in the clay mineral. The reaction conditions are set such that the above-mentioned requirements are met, with a temperature of 60 to 600 C and a time of 10 to 600 minutes. The extraction of the soluble base components from the reaction product is carried out in an aqueous medium with a pH below 1 so that their hydrolysis is prevented.

It is desirable that the particle size of the acid-treated clay is as fine as possible, and particles with a particle size of 5μ or less account for 20% by weight or more of the total,
In particular, it is preferable to use the particles in the reaction after adjusting the particle size so that the particle size is 0% by weight or more and the particle size larger than 20μ is smaller than the total 30% by weight, especially less than 10% by weight.

As other silica raw materials, silica gel, silica flour, silica sand powder, whitebait, etc. can also be used.

As the zinc raw material, a zinc oxide (zinc white), a hydroxide, or a compound capable of forming the above-mentioned oxide or hydroxide under reaction conditions can be used. A typical example of such a compound is zinc carbonate.

The ratio of both raw materials is stoichiometric.

During hydrothermal treatment, both raw materials are made into an aqueous slurry with a solid content concentration of 2 to 30% by weight, and this aqueous slurry is charged into an autoclave and heated. Make it react. As reaction conditions, a temperature of 110 to 200 C is used, in which case the pressure of the reaction system is maintained at 0.5 to 15.5 Kf/-gauge.

The reaction time varies depending on the temperature and pressure, but the reaction time is 0.
A range of 5 to 10 hours is suitable. Although reaction under pressure is preferred, zinc silicate minerals can also be obtained by hydrothermal treatment under non-pressurized conditions.

If necessary, the product is washed with water, dried, and subjected to post-treatments such as crushing and classification to obtain a product.

Organic color developer In the present invention, the above-mentioned hemimorphite type and/or
Alternatively, willemite type zinc silicate is used as a color developer in combination with a phenolic hydroxyl group-containing organic compound.

Suitable examples of such phenolic hydroxyl group-containing organic compounds are aromatic oxycarboxylic acids or metal salts thereof, or phenolic resins, especially novolac type phenolic resins.

Specific compound names of the former are as follows, although they are not limited thereto.

6.5-diisopropylsalicylic acid, 5-tartbutylsalicylic acid, 5-cyclohexylsalicylic acid, 5-phenylsalicylic acid, 5-(α,α-dimethylbenzyl)salicylic acid, 3.5-ditertbutylsalicylic acid, 5-dicyclohexylsalicylic acid, 3.5-di(α,α-dimethylbenzyl)salicylic acid, 6-cyclohexyl-5-(α,α-dimethylbenzyl)salicylic acid, 2-hydroxy-5-methyl-1-su7 Toic acid, etc.

These compounds can also be found in the form of free oxycarboxylic acids.
Alternatively, it can also be used in the form of metal salts of zinc, magnesium, cadmium, aluminum, lead, titanium, calcium, cobalt, nickel, manganese and the like. A preferred metal salt is a zinc salt.

As the phenol resin, those obtained by condensation polymerization of various phenols and aldehydes such as formaldehyde in the presence of an acid catalyst or in the presence of an alkali catalyst and then an acid catalyst are preferably used. Examples include difunctional phenols, especially phenols in which R is an alkyl group, a cycloalkyl group, or an aryl group, especially P-cresol, ρ-ethylphenol, P-terjarifthylphenol, p- Examples include cyclohexylphenol and P-7enylphenol. The molecular weight of the phenolic resin used is generally 250.
It is desirable that the value be in the range of i to o o o. These phenolic resins can also be used in the form of metal salts, such as zinc salts.

Composition As mentioned above, the color developer composition for pressure-sensitive paper in the present invention is characterized in that it contains a combination of a synthetic hemimorphite type and/or willemite type zinc silicate mineral and a phenolic hydroxyl group-containing compound. It is. That is, as shown in the example below, the above-mentioned zinc silicate mineral shows almost no coloring performance against leuco dyes when used alone, but by combining this mineral with a phenolic hydroxyl group-containing compound, it improves image quality. Density and sharpness can be significantly improved, and light resistance (discoloration and fading tendency) when subjected to a light exposure test is also significantly improved.

Moreover, it has little to no pre-existing deterioration that is seen in organic color developers. The reason for this is not exactly known, but it is thought that this zinc silicate mineral has a large oil absorption capacity and supports an organic color developer on its surface to impart a pigment effect.

What are synthetic zinc silicate and phenolic hydroxyl group-containing compounds?
60:40 to 98:2, especially 75:25 to 95:5
It is best to use a weight ratio of If the amount ratio of the zinc silicate mineral is outside the above range, there will be no synergistic effect in improving density and sharpness, and there will be no particular advantage from using the two in combination.

In addition to the above-mentioned components, the color developer composition of the present invention may contain components known per se in accordance with known formulations. For example, a binder may be added to impart adhesion or adhesion to paper.

As the binder, water-based latex binders such as styrene-butadiene copolymer latex; self-emulsifying binders such as self-emulsifying acrylic resins; water-soluble binders such as carboxymethyl cellulose, polyvinyl alcohol, cyanoethylated One or a combination of two or more of starch, casein, etc. may be used.

In addition, the amount of the composition for coating on paper may be increased, or the writing characteristics may be improved.
Other inert fillers such as kaolin, calcium carbonate, talc, zinc oxide, etc. can be incorporated to further improve printing properties.

The leuco dye developer composition of the present invention is particularly useful for producing stamp paper for pressure-sensitive recording. When manufacturing stamp paper, use a combination color developer of 5 to 5 o! Takashi, especially 15 to 40
i1t% and a binder in an amount of 1 to 10% by weight, especially 6 to 8% by weight, and a color developer in an amount of 1 to 101/? , especially from Ro to 8f/rr? Apply a coating amount such that , and dry.

The developer compositions of the present invention also exhibit many advantages in the production of pressure sensitive papers. That is, when used as a color developer for this leuco dye, it provides extremely significant advantages over conventional inorganic solid acid color developers in terms of coatability, workability, and handling as recording paper. Acid-treated products of montmorillonite clay minerals, which are currently used industrially as color developers for pressure-sensitive paper, are
The viscosity of an aqueous coating solution is high, making it difficult to apply at a high concentration, and the disadvantage is that it requires high heat energy costs for drying because it must be applied at a low solids concentration. . This is thought to be primarily due to the fact that the acid-treated clays have a swellability with water. The synthetic zinc silicate mineral used as a component in the present invention has little tendency to increase viscosity even at relatively high solids concentrations, and has excellent coating properties, thereby reducing drying energy costs in the coating process. It can be done.

In addition, the above-mentioned acid-treated clay mineral has a high abrasion tendency, and tends to abrade various tools and equipment in the pressure-sensitive paper manufacturing process, and may also peel off from the coating layer. Although there is a tendency for leuco dye capsules to break and form so-called smut, the synthetic zinc silicate mineral used in the present invention has less tendency to wear, peel off, and smudge.

Furthermore, this composition containing synthetic zinc silicate has excellent adhesion or adhesion to paper, and can be applied to paper with a small amount of binder.

In the present invention, as the leuco dye, all the leuco dyes used in pressure-sensitive recording can be used, such as triphenylmethane-based leuco dyes, fluoran-based leuco dyes, spiropyran-based leuco dyes, and rhodamine lactam-based leuco dyes. Leuco dyes, aura-jy-based ey-ico dyes, phenothiazine-based leuco dyes, and the like may be used alone or in combination of two or more. In combination with a top paper provided with a layer of microcapsules of these leuco dyes, it is used for pressure-sensitive recording.

The invention is illustrated by the following example.

Test method The test method for each item in this specification is as follows.
, counting device 5071) was used.

The diffraction conditions are as follows.

Target Cu Filter Ni Detector SC Voltage 55KVP Current
15mA Count Full Scale 8000% Time Constant 1 Formula % Formula % Chart Speed 2cW1/IIEi Radiation Angle 1° Slit Width 0.6 Direct Light Angle 6°2, BET Specific Surface Area [S, A] The specific surface area of each powder is So-called BE due to adsorption of nitrogen gas
Measured in ° according to the T method. For details, please refer to the following literature.

S, Brunauer, P, H, Emmettt.
, E. Te1ler.

J, Am, Chtm, Soc, Vol, 6
0.309 (1938) In this specification, the specific surface area is measured by drying it in advance to 150C, placing it in a 0.5 to 0.62 weighing bottle, drying it for 1 hour in a constant temperature drying oven at 150C, and immediately Weigh the burden of responsibility. This sample was placed in an adsorption sample tube and heated to 200C, degassed until the degree of vacuum within the adsorption sample tube reached 10-'rmHq, and after cooling, the adsorption sample tube was placed in liquid nitrogen at approximately -196C, and FM ! /7'Q = 4 to 5 points N between 0.05 and 0.30 (P's: nitrogen gas pressure, Po = sub-time regular atmospheric pressure)
, measure the amount of gas adsorbed. Then, the dead volume is subtracted by M, and the adsorption amount of gas is converted to the adsorption amount of 0C11 atm, and BE
By substituting into Equation T, yrn [cc/l] (indicating the amount of nitrogen gas adsorption required to form a monomolecular layer on the sample surface) is determined. Specific surface area S, Am 4.35 X Vm [rr?
/9] 3. Place the receiving paper in a desiccator (75 RE) containing saturated saline and store it in a dark place at room temperature (25 tZ').

After application, take it out from the device for about 24 hours and store it indoors (at constant temperature).
After being exposed to constant humidity (temperature: about 25C, humidity: about 60% RH) for 16 hours, the color is developed. Color development is done using the instant color-forming leuco dye CV L (Crystal VioletLact).
Mainly B L M B (Benzoyl one)
Leuc.

A commercially available transfer paper coated with microcapsules containing an auxiliary mixture of Methylene Blue and Fluoran-based leuco dye (coloring red) and the receiving paper were stacked so that the coated surfaces faced each other. This is done by rotating the microcapsules between two steel rolls under pressure to crush the microcapsules almost completely.

The color developing ability of each receiving paper is determined by measuring the color development (color development) density (hereinafter simply referred to as density) after 1 hour of color development (color development) using a densitometer (manufactured by Fuji Photo Film Co., Ltd., Fu)'t DerLsitomet.
erModel, FSD-103) and expressed as the concentration value. A high concentration indicates a high color developing ability.

4. Color change and fading The color-receiving stamp paper used for measurement in the above (3. Developing ability measurement) was exposed indoors under the same conditions, and 15 days later, the density of the faded color surface was measured using a densitometer. and the residual concentration.

In addition, at this time, the discoloration and fading of the colored surface of the receiving paper and the yellowing of the pack ground are visually observed to determine the quality.

5. Desensitizing ink coating properties Flexo type desensitizing infra-ethyl acetate and IPA using ethylene oxide adduct of stearylamine as desensitizing agent
Diluted with a (1:1) mixed solvent of denatured alcohol (ink:
A drop of solvent 1:9) L was applied onto the receiving paper using a dropper and air-dried. The obtained desensitized ink-coated receiving stamp paper was stacked so that the transfer paper and the coated surface faced each other in the same manner as in the method described above (3. Developing ability measurement), and the paper was sandwiched between two steel rolls and rotated under pressure. The microcapsules are crushed almost completely. At this time, visually observe the surface coated with the desensitized ink to see if it is difficult to develop color (desensitization) and judge whether it is good or bad. Further, one drop of undiluted desensitized ink is dropped onto the receiving paper using a dropper, and the ease with which the ink dries (easiness of ink setting) is visually observed to judge whether it is good or bad.

Reference example 1゜Ododo, Shibata City, Niigata Prefecture, coarsely crushed acidic clay +7) (
water 32.4%) 740t [25% i Add 9 to acid 3,
After heating at 95c for 10 hours and once removing the treatment solution by exposing it to P, 25t of sulfuric acid was added again, and 95t of
An acid treatment was performed by heating at Z' for 10 hours. The cake was washed with water by filtration to obtain a cake. A small amount of the cake is 110tZ'
After drying, pulverizing, and quantitative analysis, the result was 91.
5% (110c dry matter basis).The obtained cake was placed in a bot mill, water was added, and it was wet-milled with Korean balls to obtain a slurry containing 15 grams of S i 04 min. (1st step) Next, the obtained slurry 200f (si□, minute: 30t
] and 62 tons of zinc oxide (reagent grade) were placed in a 1 ton autoclave container, and 370@ of water was added, and the mixture was heated at 500 rpm.
A hydrothermal synthesis reaction was carried out at 170 t:' for 5 hours under stirring conditions for 5 hours. After cooling, the reaction product was taken out, water was separated by filtration, and then dried at 130C. The dried product was ground with a small tabletop sample to obtain a fine white powder. (Second Step) When the crystal was analyzed by X-ray diffraction, it was found to be hemimorphite zinc solosilicate.

Example 1゜Synthetic hemimorphite type zinc solosilicate obtained in Reference Example 1 and 3.5% as a phenolic hydroxyl group-containing organic compound
- A color developer composition containing zinc diisopropyl salicylate and a pressure-sensitive paper stamp paper coated with the developer composition were prepared as follows.

Sodium hexametaphosphate 0.2 to 151 parts water? and 0.01 t of sodium hydroxide, 9 t of the above-mentioned hemimorphite type zinc solosilicate powder and 1? After adding and dispersing, starch (manufactured by Nihon Shokuhin Kako ■, MS4800) was added as a binder.
A 10% aqueous solution of 101 and 504SBR latex (Do
w 620) 22 was added. A 1'0% aqueous sodium hydroxide solution was added to adjust the pH to 9, water was further added to bring the total amount to 401, and the mixture was thoroughly stirred to obtain a uniform coating solution.

The coating liquid thus obtained was 40S'/W? 6f/ on the original paper of
Coating rod (
It was applied using a wire diameter of 0.15H to 0.25 rm), air-dried, and then dried for 3 minutes in a dryer at 110C to obtain a stamp paper.

Example 2: A color developer composition containing the synthetic hemimorphite zinc solosilicate obtained in Reference Example 1, a phenolic hydroxyl group-containing organic compound, and a P-phenylphenol-formaldehyde condensation resin, and coating it thereon. A stamp paper for pressure-sensitive paper was prepared as follows.

Example 1 was carried out in exactly the same manner as in Example 1, except that 2.5 l of a 4C1 suspension of P-phenylphenol-formaldehyde condensation resin was used instead of 1 t of zinc 3.5-diisopropylsalicylate, and the developer coating composition was A product and stamp paper coated with the product were obtained.

Reference Example 2゜Sura obtained in the first step of Reference Example 1! l-2009(Si
n, 30? ) and zinc oxide (reagent-grade) 622 in a 1 ton autoclave container, add water 3702, and
A hydrothermal synthesis reaction was carried out at 250 ports for 5 hours under stirring conditions of 0.00 rpm. After cooling, the reaction product was taken out, water was separated by filtration, and then dried at 130 tZ'. The dried product was ground in a tabletop small sample mill to obtain a fine white powder.

When the crystal was analyzed by X-ray diffraction, it was found to be willemite type zinc nesosilicate.

Example 3: Synthetic willemite-type zinc nesosilicate obtained in Reference Example 2, zinc 6-cyclohexyl 5-(α,α-dimethylbenzyl)salicylate as an organic compound containing a phenolic hydroxyl group, and kaolin as a general inorganic pigment. A color developer composition containing zinc oxide and a stamp paper for pressure-sensitive paper coated with the same were prepared as follows.

Dissolve 0.2f of sodium hexametaphosphate and 0.01P of sodium hydroxide in water 152, and add the willemite type zinc nesosilicate powder 51 and 3-cyclohexyl 5-(
α, α-dimethylbenzyl) zinc salicylate 1F, kaolin powder (manufactured by IN Hieva ■, Hydrasperse) 22
After adding and dispersing 2f of zinc oxide (manufactured by Wako Tsumugi Kogyo Co., Ltd., reagent grade 1), 10% starch aqueous solution 101 and 2f of 50% SBR latex were added as binders.

Adjust the pH to 9 by adding 10% sodium hydroxide,
Further water was added to bring the total amount to 4Of, and the mixture was thoroughly stirred to obtain a uniform coating solution.

The coating liquid thus obtained was 40t/rr? 6 tons per base paper
The coating rod (
Wire diameter: 0.15 mm to 0.25 mm) was applied, and after air drying, it was dried for 6 minutes in a dryer at 110 C to obtain a stamp paper.

Example 4゜A color developer containing the synthetic willemite type zinc silicate obtained in Reference Example 2, P-tertiarybutylphenol-formaldehyde condensation resin as an organic compound containing a phenolic hydroxyl group, and kaolin and calcium carbonate as general inorganic pigments. The agent composition and a pressure-sensitive paper stamp coated with the same were prepared as follows.

In Example 3, 3-cyclohexyl 5-(α, α-
p- instead of zinc dimethylbenzyl) salicylate 1f
40% suspension of tertiary butylphenol-formaldehyde condensation resin 2.52 and light calcium carbonate (manufactured by Shiraishi Kogyo ■, Bu!J IJ) instead of zinc oxide 22
7nt15)2? A color developer coating composition and a stamp paper coated with the same were obtained by carrying out the procedure in exactly the same manner except for using the same method.

Comparative Example 1 The same method as in Example 1 was repeated except that 4.52% of kaolin powder and 4.52% of zinc oxide were used in place of the hemimorphite-type zinc solosilicate powder 92, and the color developer coating was A liquid composition and stamp paper coated with the liquid composition were obtained.

Comparative Example 2 In Example 2, 4.51% of kaolin powder and 4.5% of light calcium carbonate were used instead of 9v of hemimorphite zinc solosilicate powder. A color developer coating composition and a stamp paper coated with the same were obtained by carrying out the procedure in exactly the same manner except for using the same method.

Comparative example.

In Example 1, the amount of sodium hydroxide was increased to 0.12 and 9f of hemimorphite zinc solosilicate powder was used.
In place of the conventionally known inorganic color developer (or filler), JILTON (manufactured by Mizusawa Chemical Industry ■) 4f, kaolin powder 2.
EXAMPLE 51 and zinc oxide 2.57 were used to obtain a color developer coating composition and stamp paper coated with the developer coating composition.

Comparative Example 4 In Example 2, the amount of II (hydroxide) was increased to 0.12, and instead of hemimorphite type zinc solosilicate powder 91, Zilton 4F and kaolin powder 2.59 were used.
The same method was used except that 2.59% of light calcium carbonate was used to obtain a color developer coating composition and stamp paper coated with the developer coating composition.

Comparative Example 5゜Water 15f! I) Dissolve 0.2t of rum and add Zilton 10?, a conventionally known inorganic color developer. After adding and dispersing, add 10F of 10T starch aqueous solution and 50% sB as a binder.
2 tons of R latex was added. A 10% sodium hydroxide aqueous solution was added to adjust the pH to 95, water was further added to make the total amount 401, and the mixture was thoroughly stirred to obtain a uniform coating solution.

The following procedure was carried out in exactly the same manner as in Example 1 to obtain a color developer coating composition and stamp paper coated with the same. The test results of the covered pressure-sensitive paper stamp paper are shown in Table 1 in comparison with Comparative Examples 1 to 5.

Effects of the Invention As mentioned above, the color developer composition for pressure-sensitive paper of the present invention can form images with superior density and clarity compared to conventional color developers by contacting with leuco dyes. In addition, the pressure-sensitive paper using this composition has almost no tendency to discolor or fade due to the formed image or background light, and this composition also has outstanding coatability on paper. It has the advantage of being

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction spectrum of synthetic hemimorphite type zinc solosilicate used in Examples 1 and 2 of the present invention using α-rays for Cu-. Figure 2 shows the X-
This is a line diffraction spectrum.

Claims (6)

[Claims] (1) A color developer for pressure-sensitive paper characterized by containing a synthetic zinc silicate mineral selected from the group consisting of synthetic hemimorphite-type zinc sorosilicate and synthetic willemite-type zinc nesosilicate, and an organic compound containing a phenolic hydroxyl group. agent composition. (2) The composition according to claim 1, which contains the synthetic zinc silicate mineral and the phenolic hydroxyl group-containing organic compound in a weight ratio of 60:40 to 98:2. (3) Synthetic zinc silicate mineral 60 to 120ml/10
The composition according to claim 1, which has an oil absorption of 0 g. (4) The composition according to claim 1, wherein the synthetic zinc silicate mineral has a specific surface area of 5 to 80 m^2/g. (5) Claim 1, wherein the phenolic hydroxyl group-containing organic compound is an aromatic oxycarboxylic acid or a metal salt thereof.
Compositions as described in Section. (6) The composition according to claim 1, wherein the phenolic hydroxyl group-containing organic compound is a phenolic resin.