JPS62109679A - Stipple printing method - Google Patents

Abstract

PURPOSE:To obtain a pattern of good sprinkly colored and multicolored effects etc., by a method wherein an emulsion of a mixture consisting of a low-water- soluble dyestuff reacting with an acid substance to be colored, the acid substance, and a low-water-soluble solvent of 150 deg.C or more boiling point is coated with a resin of film-forming properties. CONSTITUTION:A low-water-soluble dyestuff reacting with an acid substance to be colored, the acid substance acting as a coupler for the low-water-soluble dyestuff, and a low-water-soluble solvent of 150 deg.C or more boiling point are mixed, and the resulting mixture is emulsified in water to prepare an emulsion. After being coated with a film forming resin, the emulsion is crosslinked and set to obtain water-insoluble coloring particles, and the particles of one or more color(s) are compounded in a printing paste consisting of a synthetic resin etc. The printing paste is so treated as to be printed on an adherend, thus a stipple pattern is developed thereon. As the low-water-soluble dyestuff reacting with the acid substance to be colored, a proton sensitive dye etc. is used.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention uses colored particles that have high tinting power, extremely vivid colors, and excellent durability, and is used to apply various small particles onto a colored object. The present invention relates to a novel pointillist printing method that makes a pattern formed by a collection of points as constituent elements appear, and allows the printing pattern to exhibit marbling effects, multicolor effects, three-dimensional effects, color change effects, etc. in the visual sense.

[Prior Art] Conventionally, a colored surface printed with a colored paste used in a normal textile printing method visually appears as a uniform color having at least an area.

In order to print marbling or colorful dotted patterns on the colored surface, several types of printing pastes are prepared according to the desired number of colors.
It is necessary to prepare special templates prepared for each dot pattern in the same number as the number of colors and print each one, and there are large restrictions on the rebeat of the pattern and the size of the dots.

In contrast, the present inventors have already devised a method for easily obtaining any pointillist pattern without requiring such complicated operations.
Publication No. 0-19670, Publication No. 51-28755, Japanese Patent Publication No. 50-29551, and Japanese Patent Publication No. 50-34
This was disclosed in Publication No. 151, etc.

[Problems to be solved by the invention] Among these new pointillist printing methods mentioned above,
The invention disclosed in Publication No. 34151 is characterized in that the color component of the colored particles is a pigment, and that it is used for fabrics etc. in accordance with the so-called pigment resin printing method. It is extremely useful in that it allows you to choose the object to be colored. However, although the invention has excellent durability because the color is pigment-based, there are some dissatisfaction with the sharpness and coloring power.

Therefore, in order to improve this color problem, the present inventors have decided to use so-called leuco dyes, that is, acidic substances, which have been commonly used in pressure-sensitive and heat-sensitive copying paper as dye components. With a colorless or light-colored poorly water-soluble pigment that develops a color,
We have found that the object can be achieved very effectively by forming a mixture of the poorly water-soluble dye, an acidic substance as a coloring agent, and a solvent that dissolves both into appropriate water-insoluble particles.

By the way, the above coloring mechanism is well known as the principle of the copying method. However, in conventional copying methods, the object to be colored is paper, and the dye and coloring agent are prepared separately, and not only do they come into contact only on the paper, but the colored material itself has almost no property other than light resistance. Furthermore, while the component particulate materials used in these copying methods only require pressure destruction or thermal destruction, the particulate materials of the present invention can be used on any coloring material. It must have strong, non-destructive performance at least semi-permanently.

The problems that must be solved in order to use the coloring mechanism conventionally used in copying methods for pointillist printing include the above-mentioned problems.

[Means for solving problems] Next, the configuration of the present invention will be described.

The present invention emulsifies in water a mixture consisting of a poorly water-soluble dye that develops color with an acidic substance, an acidic substance as a coloring agent for the poorly water-soluble dye, and a poorly water-soluble solvent with a boiling point of 150°C or higher, and then forms a film from the emulsion. By blending one or more colors of water-insoluble colored particles obtained by coating with a synthetic resin and crosslinking and curing into a printing paste made of synthetic resin, etc., and applying it on the object to be colored. , a pointillist printing method characterized by making a pointillist pattern of clear, deep and solid color appear on the object to be colored.

[Example] Examples of poorly water-soluble dyes that develop color with acidic substances used in the present invention include so-called proton-sensitive dyes, such as 3-3
'Dimethoxyfluorane (yellow in acid, hereinafter referred to as "in acid")
omitted. ), 3-chloro-6-phenylaminofluorane (orange), 3-diethylamino-6-methyl-7-chlorofluoran (vermilion), 3-diethyl-7-8 benzofluorane (
peach), 3, 3', 3°' tris (P dimethylaminophenyl) phthalide (dark blue), 3, 3' bis (P dimethylaminophenyl) phthalide (green), 3 diethylamino, 6 methyl, 7 phenylaminofluor Phenyl-substituted methane derivatives such as oran (black), fluorans, four types each of indolylphthalides, and spiropyrans.

Examples include colorless to light-colored pigment bases selected from coumarins, etc. In the present invention, these dyes are arbitrarily selected and used, but the colors of these dyes vary in terms of coloring power, sharpness, hue selectivity, etc. , all of which are superior to ordinary pigments.

Next, examples of acidic substances that color the pigments in the present invention include phthalic acid and benzoic acid.

Terephthalic acid, pyromellitic acid, trimellitic acid, toluic acid, oxystearic acid, oxalic acid.

Carboxylic acids such as lauric acid, stearic acid, tartaric acid, citric acid, anthranilic acid, etc., and their ammonium or metal salts, phenol, P-phenylphenol, β-naphthol.

Resorcinol, phloroglycin, hydroquinone, dihydroxynaphthalene, bisphenol S, phenolphtacin. Phenols and their salts such as phenolic resin oligomers, oxycarboxylic acids such as salicylic acid, oxybenzoic acid, ethyl oxybenzoate, salomethyl, resorcinic acid, methylenebissalicylic acid, salicylic acid amide, methyl β-oxynaphthoate, etc. Salts, various thiophenols and their derivatives, triazoles, tetrazoles, mercapto group-containing heterocyclic compounds, thiourea derivatives, phosphoric acid esters, sulfonated products, and inorganic compounds such as zinc chloride, tin chloride, antimony oxychloride, etc. etc., and one or more of these may be used in the present invention.

In this case, the durability and sharpness of the coloring material are significantly affected by the acidic substance, so its selection is extremely important.Specifically, as the acidic substance used in the present invention, In order to avoid adverse effects and facilitate encapsulation, colorless or light-colored, water-insoluble or poorly water-soluble substances are particularly preferred.

In the present invention, the poorly water-soluble solvent with a boiling point of 150°C or higher is one that can dissolve the acidic substance and pigments, that is, one that facilitates contact between the two and acts as a carrier for the coloring material. In the present invention, for example, mesitylene, tetralin, para? Hydrocarbons such as ester, squalane, naphthalene, diethylbenzene, dodecylbenzene, bicyclohexyl, diphenyl, cyclohexylbenzene, etc., dihalogenated hydrocarbons such as dichlorobenzene, chlornaphthalene, diphenyl chloride, trichlorotoluene, etc., many vegetable oils, animal oil,
Mineral oils and waxes, alcohols such as benzyl alcohol, octadecyl alcohol, nonyl alcohol, terpineol, etc., pendel ethyl ether, phenetol, butylphenyl ether, ethylene glycol dibutyl ether, crown ether, β-naphthol methyl ether, dimethoxybenzene, etc. Ethers, benzyl acetate, tricresyl phosphate, butyl stearate, esters such as lauryl stearate, phenyl benzoate, dibutyl phthalate, caprylamide, stearylamide, N-methyl lauramide,
Amides such as acedoanilide, urea, diphenylurea, and phthalimide; ketones such as isophorone and cyclohexanone; and the like, and in the present invention, these may be used alone or in combination of two or more. In addition, the reason why the boiling point of these poorly water-soluble solvents can be limited to 150°C or higher in the present invention is that solvents with lower boiling points are generally water-soluble or highly volatile, and are difficult to mix with both the above-mentioned dye and acidic substance. This is because the stability of

Next, in the present invention, the above-mentioned components, that is, a poorly water-soluble pigment that develops color with an acidic substance, an acidic substance, and a solvent with a boiling point of 1°50°C or higher, are uniformly mixed or melted, or either A mixture obtained by making a dispersion of the components is emulsified in water. In such a case, a known emulsifier,
A homogeneous emulsion is made using a dispersant or protective colloid and high-speed stirring or ultrasonic waves.

In the present invention, a film-forming resin having a desired function is further added to the emulsion to coat the mixture. Examples of the film-forming resin include acrylic ester resin, vinyl acetate resin, Ethylene copolymer resin, polyester resin.

Nylon resin, vinyl chloride resin, vinylidene chloride resin,
Styrene/malevidic acid copolymer resin.

Thermoplastic resins and phenolic resins such as ethylene/maleic acid copolymer resins, polyvinyl alcohol/vinyl acetate resins, polyolefin resins, urethane resins, etc.
Examples include thermosetting resins such as epoxy resins and unsaturated polyester resins, and emulsion particles coated with these film-forming resins include melamine resins and urea resins.

Epoxy resin etc. or formaldehyde.

It is cross-linked and cured with acid chloride, epichlorohydrin, incyanate compounds, acids, etc., and the colored particles thus produced have a clear color with extremely high tinting power, are water-insoluble, and are easily removed during the printing process. Or it will become something strong that will be difficult to destroy even in the future.

Incidentally, these colored particles are produced as spheres having a diameter of approximately 0.001 to 0.2 mm, and the particle size of the spheres can generally be easily controlled by adjusting the stirring speed and the amount of emulsifier.

The colored particles according to the present invention are then filtered from water,
One or more colors are blended in a printing paste made of a synthetic resin or the like in the form of a wet wet cake or dry powder, and the synthetic resin that holds the colored particles in the printing paste is Emulsions, solvent solutions, plastisols, or UV-curable compositions of the same type as those selected from film-forming resins and crosslinking resins can be optionally used. In addition to the resin, various agents such as surfactants, thickeners, drying regulators, and catalysts may be added as necessary.

Crosslinking materials, solvents, ultraviolet absorbers, antioxidants, anti-aging agents,
Antifoaming agents, fats and oils, preservatives, etc., extender pigments (filling agents), dyes and pigments, optical brighteners, metal powders, glitter pigments, glass bulbs, fragrances, etc. 9. Foaming agents, etc. may be blended; Do not deviate from the gist of the invention.

The printing paste obtained in this way is applied onto the object to be colored by a normal printing method, such as roll printing, gravure printing, screen printing, spraying, flexography, offset, coating, and padding. .

The objects to be colored in the present invention include natural fibers such as cotton, hemp, silk, and wool, recycled or semi-synthetic fibers such as rayon, cupro, and acetate, and polyolefins, polyamides, polyurethanes, polyesters, polyacrylics, and polyhalogens. Examples include woven fabrics of synthetic fibers such as vinyl chloride, S materials or mixtures thereof, films thereof or laminates thereof, and nonwoven paper.

Next, the printed colored object is dry heated as necessary.

It is subjected to treatments such as steaming and UV irradiation, thus revealing a pointillist pattern consisting of clear and rich colors.

Next, specific examples of the present invention will be shown.

-11 Example 1 30 parts by weight of paraffin wax (hereinafter, the filler is simply referred to as "part"), 10 parts of stearamide, and 4 parts of crystal violet lactone.

Zinc salicylate 6 parts, Ebiko) 828 (trade name: manufactured by Yuka Shell Co., Ltd., epoxy resin) 15 parts.

A homogeneous hot solution of 4 parts of Super Beckamine, T-"820 (product name: Nippon Reichhold Co., Ltd., butylated melamine) was poured into 150 parts of a 20% polyvinyl alcohol aqueous solution heated to 85°C, with stirring. Adjust the speed to disperse into oil droplets with an average particle size of 50IL, then add 6 parts of Ebicure U (trade name: manufactured by Yuka Shell Co., Ltd., curing agent), and continue to heat and stir at 85°C for 3 hours. Subsequently, the produced microcapsule particles were filtered through a screen gauze, washed with water, and dehydrated to obtain 80 parts of blue-purple colored particles containing 20% water content.

80 parts of the colored particles were mixed and stirred with 2 parts of Demol SS (trade name: 9 dispersant manufactured by Kao Soap Co., Ltd.) in 200 parts of water, heated to 85°C, and mixed with Denacol EX313 (trade name: Nagase Biochemical Co., Ltd.). Made.

Add 5 parts of water-soluble epoxy resin, then add 0.1 part of triethyltetramine, and continue heating at 85°C for 2 hours to harden the epoxy resin and form extremely strong colored particles, which are filtered out. After washing with water and drying, 67 parts of a blue-purple colored particle powder with a particle size of 50 liters is obtained. 10 parts of the colored particles thus obtained were added to a mixture of 15 parts of an acrylic acid ester emulsion copolymer (solid content 33%) and 75 parts of an oil-in-water emulsion containing 1% of methyl cellulose to form a printing paste. Obtained.

Next, in the above formulation, crystal violet lactone, a so-called proton-sensitive dye, was added to 3 diethylaminobenzo 7
Printing pastes containing pink and green colored particles, respectively, were obtained in the same manner except that 8-fluorane and malachite green lactone were used.

The blue-purple, pink, and green printing pastes thus obtained were mixed in a weight ratio of 40:40:20, and the colored particles of the three colors were individually scattered in their original particle shapes. A mixed printing paste was obtained. Using the mixed printing paste, mechanical printing was performed on a cotton broadcloth fabric using a full-surface engraving roll, and after drying, a dry heat treatment was performed at 140° C. for 3 minutes. When the printed fabric thus obtained is viewed from a distance of 0.5 m, it can be observed as a colorful pointillist pattern made up of aggregations of small dots in three colors: bluish-purple, peach, and green. When viewed from above, it could be observed as a marbled plain color with a reddish-brown three-dimensional effect. In addition, the colored particles were not destroyed during the printing process, and the hue was clearer and the coloring power was better than that of conventional pointillist printed fabrics using pigments, and the washing fastness and rubbing fastness were also good. .

Example 2 25 parts of behenyl alcohol, 12 parts of lauryl stearate
parts, 3 parts diethylamino, 6 methyl, 7 chlorofluorane, 5 parts (8) Chlor 1, 2,3 benzotriazoyl 3 parts, bisphenol 83 parts, coronet) T100 (
Product name 2 (manufactured by Nippon Boliutan Co., Ltd., polyvalent isocyanate) 1
0 part was heated and dissolved in advance, and this was heated and dissolved in Fuji Chemi H.
A 5% aqueous solution of ECK-150 (trade name: hydroxyethyl cellulose, manufactured by Fuji Chemical Co., Ltd.) is poured into a 200:fIA solution with stirring, and the stirring speed is adjusted to form a fine particle suspension with an average particle size of 20 liters. Furthermore, Niraporan 1066 (
Gradually drop 20 parts of polyol (product name: 2, produced by Nippon Polyurethane Co., Ltd.) and stir at 45 to 55°C for 8 hours to produce Yaikuro capsule particles, which are separated by filtration through a screen gauze, washed with water,
Dehydrated. In this way, 96 parts of vermilion colored particles containing 20% water content and having an average particle size of 25 IL were obtained. Further, 96 parts of the colored particles were mixed with 2 parts of Demol N (trade name: 9 dispersant manufactured by Kao Soap Co., Ltd.) in 250 g of water, heated to 85°C with stirring, and Sumitex Resin 260 (trade name: Sumitomo Chemical Co., Ltd.) 4 parts of urea resin (manufactured by Sumitomo Chemical Co., Ltd.) were added, and then 0.
Addition of 2 parts and continued heating for 3 hours cures the urea resin, resulting in extremely robust colorant-containing capsules. These were collected by filtration, washed with water, and dried to obtain 73 parts of vermilion particle powder with an average particle size of 25 IL. 10 parts of the colored particles thus obtained were mixed with an acrylic acid ester emulsion copolymer (solid content: 33%).
25 parts and 62 parts of oil-in-water emulsion containing 1% methyl cellulose, Sumitex Resin M-3 (trade name: manufactured by Sumitomo Chemical Co., Ltd.).

2 parts (modified methylolmelamine), 30 parts magnesium chloride
% aqueous solution was added and mixed to obtain a printing paste.

Next, in the above recipe, the so-called proton-sensitive dye, 3-diethylamino-6-methyl-7-chlorofluorane, was changed to crystal violet lactone, and everything else was done in the same manner to obtain a printing paste with blue-purple colored particles scattered therein. .

The vermilion and blue-purple printing pastes thus obtained were mixed at a weight ratio of 3, and the colored particles of the two colors were individually scattered in their original particle shapes. A printing paste was obtained. The mixed printing paste was used to print on a polyester tack fabric in an 8.0 mesh screen type (polka dot pattern), and after drying, it was subjected to dry heat treatment at 150° C. for 5 minutes to obtain a pointillist printed fabric. When this printed cloth is viewed from a distance of 0.5 m, it can be observed as a colorful polka dot pattern made up of small dots of two colors, vermilion and blue-purple. When viewed from a distance, it could be observed as a reddish-purple three-dimensional polka dot pattern due to the mixture of two colors. Furthermore, the colored particles are not destroyed during the printing process, and the pointillist printed fabric has a clearer hue and better coloring power than conventional pointillist printed fabrics using pigments, and has excellent washing fastness. The fastness to rubbing was also good.

Example 3 25 parts of cetyl alcohol, 3 parts of Crystoll 205 (trade name: Esso Standard Oil Co., Ltd., liquid paraffin), 15 parts of diphenyl, 4 parts of 3-diethylamino-6-methyl-7-phenylaminofluorane, 5 parts of bisphenol A , 2 parts of Uvinal 400 (product name: manufactured by BASF, ultraviolet absorber), and 13 parts of Rivolac 2063 (product name: manufactured by Showa Kobunshi Co., Ltd., unsaturated polyester) are heated and dissolved in advance, and this is dissolved in gelatin 6. % aqueous solution 200
the average particle size of 7 by adjusting the stirring speed.
Then, 0.3 parts of 50% benzoyl peroxide and 15 parts of cobal naphthenate were added, and the mixture was heated and stirred at 80°C for 10 hours, and the microcapsule particles formed were separated by filtration. After washing with water and drying, 62.5 black granules were obtained.

62.5 parts of such colored particles were added to 8 parts of thymol in 200 parts of water.
2 parts of Sumitex Resin A-1 (product name: Sumitomo Chemical Co., Ltd., polyacrylamide resin), 3 parts of Sumitex Resin 501 (product name: Sumitomo Chemical Co., Ltd., urea, melamine, Add 2 parts of formaldehyde initial condensate), then add 0.2 parts of Sumitex Accelerator MX (product name: Sumitex Co., Ltd., curing agent) and continue heating and stirring for 3 hours to form extremely robust colorant-containing capsules. Therefore, this was collected by filtration, washed with water, and dried to obtain 64.7 parts of black particles with an average particle size of 70 #L. 20 parts of the black particles were added to a mixture of 30 parts of an acrylic acid ester emulsion copolymer (solid content: 33%) and 50 parts of an oil-in-water emulsion containing 1% of methyl cellulose to obtain a printing paste.

Next, in the above formulation, 3 diethylaminoφ6 methyl 7 phenylaminofluorane, which is a so-called proton-sensitive dye, was added to 3
A printing paste with yellow and green colored particles interspersed therein was obtained using the same method except that diethylamino-6-methoxyfluorane and malachite green lactone were used. The black, yellow, and green printing pastes obtained in this way were mixed in a weight ratio of 10:20, and the colored particles of the three colors were individually scattered while maintaining their original particle shapes. A mixed color printing paste was obtained. Using this mixed color printing paste, a polyester/cotton mixed broadcloth fabric was printed in the same manner as in Example 1. The thus obtained printed fabric had the same effect as in Example 1, and had three colors of black, yellow and green.
It could be observed as a marbled solid color with a three-dimensional effect, consisting of small dots of color. In addition, the colored particles do not destroy the odor during or after the printing process, and compared to conventional pointillist printed fabrics using pigments, the colored particles have a clear hue and excellent coloring power, and have excellent washing fastness. The fastness to rubbing was also good.

Example 4 15 parts of oleic acid amide, 25 parts of stearyl alcohol, 3 parts of malachite green lactone, 3 parts of zinc benzoate, 3 parts of resorcinol, 10 parts of Ebico) 802 (trade name: manufactured by Yuka Shell Co., Ltd., epoxy resin) This was heated and dissolved in advance, and then poured into 150 parts of a 20% polyvinyl alcohol aqueous solution heated to 85°C with a stirrer, and the stirring speed was adjusted to disperse it in the form of oil droplets with an average particle size of 20IL. (Product name: Made by Nioilka Shell Co., Ltd., hardening agent)
After adding 4 parts of the mixture and continuing heating and stirring at 85°C for 3 hours, the microcapsule particles formed were separated by filtration, washed with water, and dried to obtain 57 parts of green spherical particles. Add 57 parts of the colored particles to Demol N (trade name: Kao Soap Co., Ltd. 9) in 200 ml of water.
Mix and stir with 2 parts of dispersant), heat to 80°C, add 5 parts of benzoguanamine formaldehyde initial condensate, then add 0.2 parts of 20% ammonium chloride aqueous solution,
When the mixture is heated and stirred for 4 hours, the benzoguanamine resin hardens and becomes an extremely strong colorant-containing capsule. This was collected by filtration, washed with water, and dried to obtain 59.5 parts of green spherical particles with an average particle diameter of 20. 10 parts of the green particles thus obtained were added to Okuno UV Color AL (trade name: manufactured by Okuno Pharmaceutical Co., Ltd., photosensitive resin).
A green printing paste was obtained by mixing 90 parts. The paste was coated over the entire surface of the P and P films using a knife coater, and then irradiated with a high-pressure mercury lamp IKW (86 W/cm) at an irradiation distance of 10 cm for 10 seconds to form a film.

The colored particles were not destroyed during printing or after printing, and exhibited a clear green color with great tinting power over the entire surface of the P film, and could be observed as a marbled tone with a three-dimensional effect.

Example 5 Green spherical particles 1 with an average particle diameter of 20 JL obtained in Example 4
5 parts, Glow Yellow MF2G (trade name: Matsui Shiki Kagaku Kogyo Co., Ltd., fluorescent pigment) 2 parts, acrylic acid ester emulsion copolymer (solid content 33%) 18 parts, methyl cellulose 1%
A printing paste was obtained by mixing 65 parts of an oil-in-water emulsion containing: Using this printing paste, we created a screen-type fabric (8) in which a large number of flower silhouette patterns were arranged on cotton broadcloth fabric.
After drying, a cotton fabric with a pointillist pattern was obtained by dry heat treatment at 140° C. for 3 minutes. When the printed fabric is viewed from a distance of 0.5 m, it can be observed as a pointillist pattern with numerous green dots arranged on a yellow ground.
When viewed from a distance of 0 m, it could be observed as a yellow-green flower pattern with a three-dimensional effect. In addition, the colored particles are not destroyed during or after the printing process, and the hue is clearer and the coloring power is superior to that of conventional pointillist printed fabrics using pigments, and the color fastness to washing and rubbing is also improved. was also good.

[Effect of the invention] Next, the effects of the present invention will be listed.

(1) The colored body obtained according to the present invention has a pattern made up of aggregation of various small dots as constituent elements, and the pattern has a marbling effect and a variegated effect.

It exhibits remarkable three-dimensional effects and color-changing effects.

(2) In the printing paste used in the present invention, if colored particles of two or more colors are individually scattered in the same form as they are in the paste, the printing paste used in the present invention can be printed even if printed with one printing plate. The colored body is
A pattern is manifested by a collection of small dots of two or more colors. Microscopically, there is a multicolor effect due to the adjacency of the dots, and macroscopically it shows a variety of colors in the visual sense. By mixing colors, a mixed color effect with a three-dimensional effect is achieved.

(3) The colored particles used in the present invention are hard granules with a uniform particle size, and depending on the manufacturing conditions, the colored particles range from 0.001 to 0.
．． Any particle size within the range of 2 mm can be obtained, and the individual colored particles in the printing paste are scattered individually while maintaining their original particle shape, and the colored particles are destroyed in the printing paste. The particles will not be dispersed uniformly and finely, and the components inside the particles will not ooze out.

Moreover, the storage stability of the printing paste is also good.

(4) The colored body obtained by the present invention has a color that is extremely clear, deep, and robust compared to conventional pigments.

Claims (1)

[Scope of Claims] 1. A mixture consisting of a poorly water-soluble dye that develops color with an acidic substance, an acidic substance serving as a coloring agent for the poorly water-soluble dye, and a poorly water-soluble solvent with a boiling point of 150° C. or higher is emulsified in water, and then the emulsification is performed. One or more colors of water-insoluble colored particles obtained by coating an object with a film-forming resin and cross-linking and curing are blended into a printing paste made of synthetic resin, etc., and the printing paste is A pointillist printing method characterized by performing a printing process on a material to be colored to reveal a pointillist pattern. 2. The pointillist printing method according to claim 1, wherein the acidic substance is colorless or light-colored and insoluble or poorly soluble in water.