JPS6247906B2 - - 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 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 have been replacing them.
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. They are simply dispersed oil-modified alkyd resins with good oil content using hydrophilic surfactants, and the coatings obtained from these paints do have good adhesion to chalky surfaces, but the pigments and binders Due to the presence of water-soluble pigment dispersants between certain oil-modified alkyd resins and synthetic resins, the current situation is that they do not have sufficient effects on wet adhesion and water resistance to coated objects. It is. The present invention solves the above drawbacks, combines the advantages of synthetic resin emulsion and oil-modified alkyd resin,
Adhesion to chalky surfaces, wet adhesion to objects to be coated,
To provide a method for producing a stable water-based paint that has excellent water resistance and durability. That is, the present invention comprises a synthetic resin emulsion (A) having a solid content of 100 parts by weight, and a drying oil-modified alkyd resin and/or a semi-drying oil that has an oil length of 20% or more, a Gardner viscosity of Z or less, and does not substantially contain a solvent. The present invention relates to a method for producing a water-based paint, which comprises mixing 10 to 150 parts by weight of a modified alkyd resin (hereinafter simply referred to as oil-modified alkyd resin) as a vehicle with a pigment paste (B) prepared by kneading a pigment. Hereinafter, the method for producing the water-based paint of the present invention will be explained in detail. As the synthetic resin emulsion used in the present invention, vinyl resin emulsions such as acrylic resin, acrylic/styrene resin, vinyl acetate resin, vinyl acetate/ethylene resin, and styrene/butadiene resin can generally be used. It is not limited to these. As the oil-modified alkyd resin, one or more selected from drying oil-modified alkyd resins and semi-drying oil-modified alkyd resins having an oil length of 20% or more, a Gardner viscosity of Z or less, and substantially containing no solvent are used. Ru. The oil length of the oil-modified alkyd resin used in the present invention is 20% or more, preferably 30% or more. If the oil length is less than 20%, the pigment paste using this as a vehicle will not be stably dispersed in the synthetic resin emulsion. The viscosity of the oil-modified alkyd resin used in the present invention is Z or less in terms of Gardner viscosity. If the oil-modified alkyd resin has a high viscosity exceeding the Gardner viscosity Z, a pigment paste using this as a vehicle will not be stably dispersed in the synthetic resin emulsion. The oil-modified alkyd resin used in the present invention is
It is necessary that it be substantially free of solvent. When an organic solvent is added to an oil-modified alkyd resin or to a pigment paste prepared by kneading pigments using this as a vehicle, when the resulting pigment paste is dispersed in a synthetic resin emulsion or water, pigment aggregation tends to occur, resulting in poor coating film formation. Only paints with significantly lower gloss can be obtained. In the present invention, the synthetic resin emulsion (A) and the pigment paste (B), which is prepared by kneading pigments using an oil-modified alkyd resin as a vehicle, are mixed. The ratio of the oil-modified alkyd resin to the oil-modified alkyd resin is 10 to 150 parts by weight, preferably 20 to 100 parts by weight. 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. Although the ratio of the oil-modified alkyd resin to the pigment can be used within a wide range, it is preferably in the range of 5 to 600 parts by weight of the latter to 100 parts by weight of the former. Further, the pigment paste (B) can be used in a wide range of times, but the preferred range is 15 to 1000 parts by weight for the synthetic resin emulsion (A), which has a solid content of 100 parts by weight. To carry out the method of the present invention, for example, the synthetic resin emulsion (A) may be added and mixed into a pigment paste (B) in which pigments are kneaded using an oil-modified alkyd resin as a vehicle, or a synthetic resin emulsion (A) may be mixed. Pigment paste (B) may be added to (A) and mixed. It is also an embodiment of the present invention to mix the pigment paste (B) and water in advance and then mix them with the synthetic resin emulsion (A). 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 synthetic resin emulsion (A) and the pigment paste (B), or it may be added at the time of mixing. Alternatively, it may be mixed in advance with the synthetic resin emulsion (A) and/or pigment paste (B). Next, the present invention will be specifically explained using examples. In the following, all parts and percentages are based on weight. Production Example 1 A synthetic resin emulsion (1) was produced according to a conventional method using 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 parts 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 2 A synthetic resin emulsion (2) was produced according to a conventional method using the following formulation. Deionized water 108 parts Methyl methacrylate 64 parts 2-ethylhexyl acrylate 35 parts Acrylic acid 1 part Polyoxyethylene nonyl phenyl ether (HLB16) 8 parts Potassium persulfate 0.5 parts After the polymerization reaction, add ammonia water to adjust the pH.
Adjusted to 9.0. The nonvolatile content of this emulsion is
50%, and the viscosity was 200 centipoise. Production example 3 1000 parts of linseed oil and pentaerythritol
111 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 the transesterification reaction was carried out for 1 hour. The mixture was then cooled to 180°C, 213 parts of phthalic anhydride was added, and the mixture was reacted at 240°C for 5 hours to obtain an alkyd resin (1) having an oil length of 77%, an acid value of 7.0, and a Gardner viscosity of W. Production Example 4 The reaction was carried out in the same manner as in Production Example 3 except that soybean oil was used instead of the linseed oil in Production Example 3 to obtain an alkyd resin (2) with an oil length of 77%, an acid value of 8.0, and a Gardner viscosity of Y. . Production Example 5 280 parts of castor oil, 197 parts of phthalic anhydride, 174 parts of adipic acid, 3 parts of fumaric acid and 346 parts of diethylene glycol were charged and heated at 205°C under a nitrogen gas atmosphere.
After a time reaction, an alkyd resin (3) having an oil length of 30%, an acid value of 10, and a Gardner viscosity of W was obtained. Production Example 6 150 parts of tung oil fatty acid, 195 parts of phthalic anhydride, 270 parts of isophthalic acid, 105 parts of trimethylolpropane and 280 parts of neopentyl glycol were charged, and reacted for 8 hours at 240°C under a nitrogen gas atmosphere until the oil length was 16
%, a comparison alkyd resin that is solid at room temperature with an acid value of 5.0
I got (1). Production Example 7 633 parts of soybean fatty acid, 185 parts of phthalic anhydride and 182 parts of pentaerythritol were charged and reacted at 210°C for 6 hours in a nitrogen gas atmosphere, resulting in oil length of 68% and acid value.
12. A comparative alkyd resin (2) with a Gardner viscosity of _Z5 was obtained. Example 1 A water-based paint (1) was produced with the following formulation. Emulsion obtained in Production Example 1 (1) 100 parts Alkyd resin obtained in Production Example 3 (1) 45 parts Titanium oxide (rutile type) 60 parts Cobalt naphthenate 0.3 parts Manganese naphthenate 0.3 parts Lead naphthenate 0.7 parts Butyl cellosolve 14 Part Texanol 4 parts Alkyd resin (1), pigment and dryer were placed in a sand mill and kneaded. Next, emulsion (1) to which butyl cellosolve and Texanol had been added in advance was added to this pigment paste, and the pigment paste was dispersed in the emulsion by vigorous stirring. The obtained water-based paint (1)
It was diluted to 70 KU with deionized water and used for the coating test. This water-based paint (1) was stable at room temperature for more than one year. Example 2 A water-based paint (2) was produced with the following formulation. Emulsion obtained in Production Example 2 (2) 100 parts Alkyd resin obtained in Production Example 4 (2) 13 parts Valve handle 20 parts Cobalt naphthenate 0.1 part Manganese naphthenate 0.1 part Lead naphthenate 0.2 parts Butyl cellosolve 16 parts Deionized water 20 parts of 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 obtained water-based paint (2) was diluted to 70 KU with deionized water and subjected to a coating test. Also, this water-based paint
(2) was stable for more than a year at room temperature. Example 3 A water-based resin was prepared in the same manner as in Example 1, except that the alkyd resin used was replaced with the alkyd resin (1) obtained in Production Example 3 and the alkyd resin (3) obtained in Production Example 5. Paint (3) was obtained. This water-based paint (3)
was stable for over a year 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 1 (1) 100 parts Alkyd resin obtained in Production Example 3 (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) in the emulsion paint. Comparative water-based paint obtained
(1) was diluted to 70 KU with deionized water and subjected to a coating test. This comparative water-based paint (1) separated into two layers when left at room temperature for 6 months, and as shown in Table 1, its water resistance and wet adhesion were significantly inferior. Comparative Example 2 A comparative water-based paint (2) was produced using the same formulation as in Example 2 in the following manner. Alkyd resin (2), butyl cellosolve, pigment, and dryer were placed in a sand mill and kneaded. Deionized water was added to the resulting pigment paste and dispersed in the water by vigorous stirring.
Next, this dispersion and emulsion (2) were mixed. The obtained comparative water-based paint (2) was diluted with deionized water to 70 KU and subjected to a coating test. In addition, the comparative water-based paint (2) had a significantly poor pigment dispersion state, and as shown in Table 1, the coating film gloss was poor. Comparative Example 3 A comparative aqueous solution was prepared in the same manner as in Example 2, except that 45 parts of the alkyd resin (1) was replaced with 75 parts of the 60% butyl cellosolve solution of the comparative alkyd resin (1) obtained in Production Example 6. A paint (3) was obtained which immediately separated into two layers. Comparative Example 4 Example 1 except that the amount of pigment paste used was blended so that the ratio of the solid content of the emulsion to the amount of alkyd resin was 100:5.
Comparative water-based paint (4) was obtained in the same manner as above. As shown in Table 1, the coating film obtained from this paint was poor in water resistance, wet adhesion, and adhesion to chalked surfaces. Comparative Example 5 Same as Example 1 except that the amount of alkyd resin used was blended so that the ratio of the solid content of the emulsion to the amount of alkyd resin was 100:180.
Comparative water-based paint (5) was obtained in the same manner as above. The coating film obtained from this paint had poor weather resistance as shown in Table 1. Comparative Example 6 Comparison was made in the same manner as in Example 1 except that the alkyd resin used in Example 1 was replaced with the comparative alkyd resin (2) obtained in Production Example 7 from the alkyd resin (1) obtained in Production Example 3. A water-based paint (6) was obtained which immediately separated into two layers. Example 4 Each water-based paint obtained in Examples 1 to 3 and Comparative Examples 1, 2, 4, and 5 was applied to a commercially available colored corrugated iron plate,
After drying at room temperature for two weeks, the coating film performance was evaluated.
The results shown in Table 1 were obtained. As shown in Table 1, Examples 1 to 3 obtained by the method of the present invention had extremely good water resistance, wet adhesion, and adhesion to chalky surfaces. 【table】

Claims (1)

[Claims] 1 Synthetic resin emulsion (A) with a solid content of 100 parts by weight, and a drying oil-modified alkyd resin and/or a semi-drying oil-modified alkyd resin with an oil length of 20% or more, a Gardner viscosity of Z or less, and substantially no solvent. A method for producing a water-based paint, which comprises mixing 150 parts by weight of a pigment with a pigment paste (B) as a vehicle.