JPS6333791B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a water-based paint. Conventionally, paints containing large amounts of aromatic or organic solvents have been widely used, but in recent years, from the viewpoint of air pollution and resource conservation, synthetic resin emulsion paints that do not use solvents are being replaced. However, coating films obtained from general emulsion paints have insufficient adhesion and water resistance, and in particular have the disadvantage of extremely poor adhesion to chalky surfaces and wet adhesion to objects to be coated. There is. In order to improve these drawbacks, a method for producing a water-based paint is known in which an oil-modified alkyd resin is dispersed in a synthetic resin emulsion paint. However, in this manufacturing method, in the process of manufacturing an emulsion paint by mixing an emulsion with a pigment paste prepared in advance by dispersing pigments in water using a water-soluble pigment dispersant, the process simply improves the permeability to chalky surfaces. The coating films obtained from these paints do have good adhesion to chalky surfaces, but the pigment and binder are simply dispersed using a hydrophilic surfactant. Since a water-soluble pigment dispersant exists between the oil-modified alkyd resin and the synthetic resin, sufficient effects have not been achieved in terms of wet adhesion and water resistance to the object to be coated. The present inventors have solved the above-mentioned drawbacks and combined the advantages of synthetic resin emulsions and oil-modified alkyd resins, and have excellent adhesion to chalky surfaces, wet adhesion to objects to be coated, water resistance, and durability. As a result of continuing research to develop water-based paints, we first developed a method for producing water-based paints that has the various advantages mentioned above by mixing a pigment paste using a specific oil-modified alkyd resin as a vehicle and a synthetic resin emulsion. He succeeded in developing it and filed a patent application (patent application 1982-
114385, Japanese Patent Application Laid-Open No. 60-6761), among these specific oil-modified alkyd resins, a resin having a residue derived from a compound having an alkylene oxide chain and a hydroxyl group in the molecule was used, which was particularly excellent. It has been discovered that it is possible to obtain a water-based paint that has good adhesion to chalky surfaces, wet adhesion to objects to be coated, water resistance, and durability, and also has good water dilution stability and high photoselectivity, and has developed the present invention. I was able to complete it. That is, the present invention provides a pigment paste [A] in which a pigment is kneaded with a vehicle whose main component is a drying oil-modified alkyd resin and/or a semi-drying oil-modified alkyd resin that does not substantially contain a solvent, and a vinyl polymer emulsion [A]. B] to produce a water-based paint, the oil-modified alkyd resin (hereinafter simply referred to as oil-modified alkyd resin) used is an essential component.

[Formula] (where R represents H or a methyl group, and n represents an integer from 3 to 300). The object of the present invention is to provide a method for producing a water-based paint, characterized in that the resin contains 0.1 to 20% by weight of the water-based paint. Hereinafter, the method for producing the water-based paint of the present invention will be explained in detail. As the vinyl polymer emulsion [B] used in the present invention, for example, acrylic resins, acrylic/styrene resins, vinyl acetate resins, vinyl acetate/ethylene resins, styrene/butadiene resins, etc. can generally be used. , but not limited to these. The oil-modified alkyd resin used in the present invention has as an essential component

[Formula] (However, R and n are as above.) Manufactured by a known method using a compound having an alkylene oxide chain and a hydroxyl group in the molecule (hereinafter referred to as compound a) . The alkylene oxide chain may be a repeat of the same structural unit, or may be a combination of different structural units randomly or in a block shape. Further, the number of hydroxyl groups may be at least one. n ranges from 3 to 300. If n is less than 3, the water dilutability will be reduced and a safe water-based paint will not be obtained, whereas if n is more than 300, the water resistance and wet adhesion to the coated object will be reduced. Examples of such compound a include polyethylene glycol, polypropylene glycol,
Polyalkylene glycols such as polyoxyethylene oxypropylene block copolymers; polyoxyethylene monoalkyl ethers; polyoxyethylene monoalkylaryl ethers; polyoxyethylene monofatty acid esters; polyoxyethylene sorbitan fatty acid esters; polyoxyethylene alkyl amines ; polyoxyethylene alkylamide; polyoxyethylene alkyl thioether; polyoxyethylene phosphate ester, etc. can be used, but the present invention is not limited to these. Oil-modified alkyd resin is obtained by cocondensing Compound A as a raw material with other raw materials, and the residue derived from Compound A is added to the resin by 0.1 to 20
It is contained in a proportion of % by weight. 0.1% by weight
If the oil-modified alkyd resin is used as a vehicle and a paste of pigment kneaded is dispersed in a vinyl polymer emulsion, water-based paints will have poor water dilution stability, causing pigment aggregation and resulting in a smooth, highly photosensitive coating film. is not obtained. In addition, if the amount exceeds 20% by weight, the hydrophilicity of such oil-modified alkyd resin becomes too high, so a paste prepared by kneading pigment using the oil-modified alkyd resin as a vehicle is dispersed in a vinyl polymer emulsion. Water resistance and wet adhesion of coating films obtained from water-based paints are significantly deteriorated. In the present invention, a pigment paste [A] is prepared by kneading a pigment with a vehicle whose main component is an oil-modified alkyd resin.
and the vinyl polymer emulsion [B] are mixed, and the oil-modified alkyd resin is mixed in an amount of 10 to 150 parts by weight, preferably 20 to 100 parts by weight, per 100 parts by weight of the solid content of the vinyl polymer emulsion [B]. This is the ratio of parts. If the amount is less than 10 parts by weight, wet adhesion to objects to be coated and adhesion to chalked surfaces will be poor. Moreover, if it exceeds 150 parts by weight, the drying properties and weather resistance of the coating film will decrease. The ratio of oil-modified alkyd resin to pigment can vary widely, but 100 parts by weight of the former to 5 parts by weight of the latter is used.
A range of 600 parts by weight is preferred. Furthermore, the pigment paste [A] can be used in a wide variety of ways, but the preferred range is from 15 to 1000 parts by weight, relative to the solid content of the vinyl polymer emulsion [B] of 100 parts by weight. The oil-modified alkyd resin used in the present invention is specified as described above, but other various alkyd resins may be used in place of a part of the oil-modified alkyd resin used in the present invention. To carry out the method of the present invention, for example, a vinyl polymer emulsion [B] may be added and mixed into a pigment paste [A] prepared by kneading pigments using an oil-modified alkyd resin as a vehicle; The pigment paste [A] may be added and mixed into the polymer emulsion [B]. It is also an embodiment of the present invention to mix the pigment paste [A] and water in advance and then mix the mixture with the vinyl polymer emulsion [B]. These are examples of the present invention, and the present invention is not limited thereto. Various additives normally added to paints can be added to the water-based paint obtained by the method of the present invention, if necessary. Examples include plasticizers, thickeners, leveling agents, antifoaming agents, antifreeze agents, preservatives, dryers, and the like. These additives are
It may be added after mixing the vinyl polymer emulsion [B] and the pigment paste [A], or it may be added at the time of mixing. Alternatively, it may be mixed in advance with the vinyl polymer emulsion [B] and/or pigment paste [A]. Next, the present invention will be specifically explained using examples. In the following, all parts and percentages are based on weight. Production example 1 1000 parts linseed oil and pentaerythritol
110 parts of the mixture was charged, the temperature was raised to 230°C under a nitrogen gas atmosphere, 0.4 parts of lithium hydroxide was added, and transesterification reaction was carried out for 1 hour. Then cooled to 180℃,
After adding 215 parts of phthalic anhydride and 40 parts of polyethylene glycol (molecular weight 4000), the mixture was reacted at 230°C for 5 hours to obtain alkyd resin [1] with an acid value of 8.0 and a Gardner viscosity of Y. Production example 2 Castor oil 280 parts, phthalic anhydride 197 parts, adipic acid 174 parts, fumaric acid 3 parts, diethylene glycol
346 parts and 100 parts of polyoxyethylene oxypropylene block copolymer (manufactured by Sanyo Kasei Co., Ltd., Newpol PE74) were charged, and the mixture was heated to 205 parts in a room under a hydrogen gas atmosphere.
React at ℃ for 5 hours, acid value 10, Gardner viscosity W
An alkyd resin [2] was obtained. Production Example 3 The reaction was carried out in the same manner as in Production Example 1 except that polyoxyethylene nonyl phenyl ether (HLB = 18) was used instead of the polyethylene glycol in Production Example 1, and an alkyd resin with an acid value of 8.0 and a Gardner viscosity of Y was obtained. 3] was obtained. Production Example 4 The reaction was carried out in the same manner as Production Example 1 except that polyethylene glycol was removed from Production Example 1, and the acid value was 7.0.
A comparative alkyd resin [1] having a Gardner viscosity of X was obtained. Production example 5 Castor oil 207 parts, phthalic anhydride 146 parts, adipic acid 129 parts, fumaric acid 2 parts, diethylene glycol
326 parts and polyethylene glycol (molecular weight
4000) was charged and reacted for 5 hours at 205°C under a nitrogen gas atmosphere to obtain a comparative alkyd resin [2] having an acid value of 6.0 and a Gardner viscosity of Y. Production Example 6 Synthetic resin emulsion [1] was produced according to a conventional method with the following formulation. Deionized water 125 parts Styrene 62 parts 2-ethylhexyl acrylate 34 parts Acrylic acid 4 parts Sodium lauryl alcohol sulfate
2 parts Potassium persulfate 0.5 part After the polymerization reaction, add aqueous ammonia to adjust the pH.
Adjusted to 8.5. The nonvolatile content of this emulsion is
45%, and the viscosity was 1500 centipoise. Production Example 7 Synthetic resin emulsion [2] was produced according to the conventional method with the following formulation. Deionized water 108 parts Methyl methacrylate 62 parts 2-ethylhexyl acrylate 35 parts Acrylic acid 3 parts Polyoxyethylene nonyl phenyl ether (HLB16) 8 parts Potassium persulfate 0.5 parts After the polymerization reaction is complete, add aqueous ammonia to bring the pH to 8.
Adjusted to. The non-volatile content of this emulsion is 50
%, and the viscosity was 500 centipoise. Example 1 A water-based paint [1] was manufactured using the following formulation. Alkyd resin [1] obtained in Production Example 1 30 parts Emulsion [1] obtained in Production Example 6 155 parts Carbon black 5 parts Cobalt naphthenate 0.3 parts Butyl cellosolve 22 parts Deionized water 38 parts Alkyd resin [1] and pigment It was placed in a sand mill and kneaded. Emulsion [2] to which butyl cellosolve and deionized water had been added in advance was added to the obtained pigment paste, and the pigment paste was dispersed in the emulsion by vigorous stirring to obtain a water-based paint with a non-volatile content of 42%. A water-based paint [1] with a viscosity of 20 seconds (foed cup) obtained by diluting this paint with deionized water until the nonvolatile content was 30% was subjected to a film test. This water-based paint [1] was stable for more than 6 months at room temperature. Example 2 A water-based paint [2] was produced with the following formulation. Alkyd resin obtained in Production Example 2 [2] 13 parts Emulsion obtained in Production Example 7 [2] 100 parts Bengara 20 parts Cobalt naphthenate 0.1 part Manganese naphthenate 0.1 part Lead naphthenate 0.2 parts Butyl cellosolve 14 parts Deionized water 20 parts Alkyd resin [2], pigment and dryer were placed in a sand mill and kneaded. Deionized water to which butyl cellosolve had been added in advance was added to the resulting pigment paste and stirred vigorously to disperse it in water. Next, this dispersion and emulsion [2] were mixed. The resulting water-based paint with a non-volatile content of 50% was diluted with deionized water until the non-volatile content was 35%.
A water-based paint [2] with a viscosity of 20 seconds (foed cup) was obtained and subjected to a coating film test. Furthermore, this water-based paint [2]
was stable for more than 6 months at room temperature. Example 3 In Example 1, the alkyd resin used was prepared from the alkyd resin [1] obtained in Production Example 1 to Production Example [3].
A water-based paint [3] was obtained in the same manner as in Example 1 except that the alkyd resin [3] obtained in Example 1 was used. This water-based paint [3] was stable for more than 6 months at room temperature. Comparative Example 1 A comparative water-based paint [1] was produced with the following formulation. Titanium oxide (rutile type) 60 parts Potassium tripolyphosphate 0.6 parts Deionized water 7.4 parts Emulsion obtained in Production Example 6 [1] 100 parts Alkyd resin obtained in Production Example 1 [1] 45 parts Polyoxyethylene nonyl phenyl ether (HLB16) 3 parts Cobalt naphthenate 0.3 parts Manganese naphthenate 0.3 parts Lead naphthenate 0.7 parts Butyl cellosolve 16 parts Pigment, potassium tripolyphosphate, and deionized water are placed in a sand mill, and the pigment is dispersed in water to obtain a pigment paste. Emulsion [1] and butyl cellosolve were mixed to obtain an emulsion paint. Next, a mixture of alkyd resin [1], a surfactant and a dryer was added to this emulsion paint, and the mixture was vigorously stirred to disperse the alkyd resin [1] into the emulsion paint. The obtained water-based paint was diluted with deionized water to a paint viscosity of 20 seconds (foed cup) to obtain a comparative water-based paint [1].
It was subjected to a coating test. In addition, this comparative water-based paint [1]
When it was left at room temperature for 6 months, it separated into two layers, and as shown in Table 1, its water resistance and wet adhesion were significantly poor. Comparative Example 2 Comparison was made in the same manner as in Example 1, except that the alkyd resin used in Example 1 was changed from the alkyd resin [1] obtained in Production Example 1 to the comparative alkyd resin [1] obtained in Production Example 4. A water-based paint [2] was obtained. When this comparative water-based paint [2] was left at room temperature for one week, the pigments precipitated, and as shown in Table 1, the paint film photoselectivity was significantly inferior. Comparative Example 3 Comparison was made in the same manner as in Example 2, except that the alkyd resin used was changed from the alkyd resin [2] obtained in Production Example 2 to the comparative alkyd resin [2] obtained in Production Example 5. A water-based paint [3] was obtained. This comparative water-based paint [3] was stable at room temperature for more than 6 months, but as shown in Table 1, it was significantly inferior in wet adhesion, adhesion to chalky surfaces, and water resistance. Example 4 Each of the water-based paints obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was spray-painted onto a mild steel plate, and after drying at room temperature for two weeks, coating film performance was evaluated, and the results shown in Table 1 were obtained. Ta. As shown in Table 1, the paint coatings obtained from Examples 1 to 3 by the method of the present invention had high optical selectivity;
The wet adhesion, adhesion to chalky surfaces and water resistance were extremely good.

【table】

Claims (1)

[Scope of Claims] 1. A pigment paste [A] obtained by kneading a pigment with a vehicle containing a substantially solvent-free drying oil-modified alkyd resin and/or a semi-drying oil-modified alkyd resin as a main component, and a vinyl polymer emulsion. [B]
When producing a water-based paint by mixing the above-mentioned oil-modified alkyd resin, the oil-modified alkyd resin used has the following formula as an essential component (wherein, R represents H or a methyl group, and n represents an integer from 3 to 300). 1. A method for producing a water-based paint, characterized in that the resin contains a residue derived from a compound having an alkylene oxide chain and a hydroxyl group in the molecule in a proportion of 0.1 to 20% by weight in the resin.