JPS6153388B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to aqueous dispersion compositions useful for coatings, and more particularly to water-repellent, water-resistant and durable compositions comprising an aqueous dispersion of a specific emulsion copolymer and a wax having a specific melting point range. sex,
The present invention relates to an aqueous dispersion composition for paint that has excellent weather resistance and stain resistance. Traditionally, aqueous dispersions have been characterized by ease of handling, workability,
It is used in large quantities for paints due to its film performance. The original purpose of paint is to protect and beautify the base material, but in particular, a high degree of weather resistance is required for external coating. However, with conventional aqueous dispersions, it has been difficult to obtain paints with excellent weather resistance unless they have sufficient repellency and water resistance. One solution to this problem is to add water repellents; however, although the addition of such water repellents is effective in imparting initial water repellency, The reality is that it not only has poor durability and weather resistance, but also has no effect on water resistance. However, the present inventors have developed an aqueous dispersion as a coating material that has high and durable water repellency, water resistance, and excellent weather resistance without impairing the excellent physical properties and workability inherent to the aqueous dispersion. As a result of intensive research to obtain a useful aqueous dispersion, the present invention has been completed. That is, the present invention comprises at least 30% by weight of a hydrophobic α/β-monoethylenically unsaturated monomer whose solubility in water is 0.3% by weight or less at 25°C, and an α/β-monoethylenically unsaturated carboxylic acid. 0.1-5% by weight
and other α/β-monoethylenically unsaturated monomers copolymerized with these and containing no functional group 0 to 70
Wax having a melting point of 50 to 100°C is added to an aqueous dispersion (A) of a copolymer with a glass transition temperature of 0 to 50°C obtained by emulsion copolymerizing a mixture of monomers consisting of % by weight.
An aqueous dispersion for paints containing 2 to 40% by weight of (B) based on the solid content of the aqueous dispersion (A), which has excellent water repellency, water resistance, durability, weather resistance, and stain resistance. The purpose is to provide body compositions. The above-mentioned "hydrophobic α/β-monoethylenically unsaturated monomer" (hereinafter referred to as "hydrophobic monomer") used to obtain the above-mentioned aqueous dispersion (A) in the composition of the present invention. refers to a monomer whose solubility in water at 25°C is 0.3% by weight or less, preferably 0.1% by weight or less, typical examples of which are butyl acrylate and 2-ethylhexyl acrylate. , butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate; styrene, α-methylstyrene; ethylene; versaticular acid vinyl ester, etc.; these may be used alone or as a mixture of two or more, It is necessary to use 30% by weight or more of the total monomers. Next, as other α/β-monoethylenically unsaturated monomers that are copolymerized with a hydrophobic monomer and α/β-monoethylenically unsaturated carboxylic acid and do not contain a functional group, examples include acrylic acid. Methyl, ethyl acrylate, methyl methacrylate; vinyl acetate, acrylonitrile, etc. are typical examples, and these may be contained in the total monomers in an amount of 0 to 70% by weight as one type or a mixture of two or more types. Furthermore, examples of the α/β-monoethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, etc.
In total monomers as species or mixture of two or more species
It is used in a range of 0.1 to 5% by weight. By the way, if the solubility in water of the above-mentioned hydrophobic monomer exceeds 0.3% by weight, the water repellency and water resistance of the resulting copolymer film will decrease, and the durability of this water repellency will decrease. Also, the copolymer composition ratio of this hydrophobic monomer is 30%.
The same problem occurs when the amount is less than % by weight, which is not preferable. In addition, when the above-mentioned other α/β-monoethylenically unsaturated monomer is contained in a large amount exceeding 70% by weight, the resulting copolymer has strong hydrophilicity, and the formed film has water repellency and water resistance. In addition, the durability of water repellency is also poor. Furthermore, regarding the α/β-monoethylenically unsaturated carboxylic acid mentioned above, when the copolymer composition ratio is extremely low, such as less than 0.1% by weight, the stability of the aqueous dispersion of the resulting copolymer decreases. , it becomes impossible to obtain a good aqueous dispersion composition, and conversely, when the amount exceeds 5% by weight, the aqueous dispersion of the copolymer becomes
Fluid viscosity is significantly affected by changes in pH, resulting in poor painting workability, and the resulting film also has poor water resistance and water repellency. In addition, functional group-containing monomers such as acrylamide, methacrylamide, N-methylol, etc., which impart crosslinking properties to copolymers made from the above-mentioned monomers by conventional heat and acidic catalysts, are also added. Copolymerizing one or more of acrylamide, N-butoxymethylol acrylamide, glycidyl acrylate, glycidyl methacrylate, β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, etc. at about 0.5 to 10% by weight. Of course, thermosetting can be imparted by copolymerization of such functional group-containing monomers, and as a result, self-crosslinking or crosslinking as a crosslinking agent can be achieved through the heat drying process commonly used during coating. It is preferable that it is crosslinked with aminoplast or the like to obtain a baked film with even better water repellency, water resistance, durability, and weather resistance. The aqueous dispersion (A), which is a component of the composition of the present invention, can be obtained by a conventional emulsion polymerization method. Examples of emulsifiers used in this case include anionic surfactants, nonionic surfactants, cationic surfactants, other reactive emulsifiers, and substances with surfactant properties such as acrylic oligomers and water-soluble polymer substances. These are one or two types.
Although more than one type of surfactant can be used in combination, it is usually preferable to use an anionic surfactant and a nonionic surfactant in combination. The amount of this emulsifier used is not particularly limited, but it is usually used in an amount of about 0.1 to 10% by weight based on the total amount of monomers. On the other hand, as a polymerization initiator, any catalyst that is generally used in emulsion polymerization can be used, but typical examples include water-soluble inorganic peroxides such as hydrogen peroxide and ammonium persulfate; These include persulfates; organic peroxides such as cumene hydroperoxide and benzoyl peroxide; and azo compounds such as azobisisobutyronitrile, and these may be used alone or as a mixture of two or more. The amount used is about 0.1 to 2% based on the total weight of the monomers. Of course, it is also possible to use a method generally known as a redox polymerization method in which these catalysts are used in combination with metal ions and reducing agents. Further, the various monomers described above may be added all at once, in parts, or continuously by dropwise addition, and in the presence of the catalyst described above, 0 to
Polymerization is carried out at a temperature of 100°C, practically 30-90°C. The copolymer obtained by such emulsion copolymerization must have a glass transition temperature within the range of 0 to 50°C. Here, the correlation between the glass transition temperature, water repellency, and water resistance was found empirically; if the temperature is below 0°C, the water repellency and water resistance are insufficient, and the film becomes sticky. In addition, contamination of the paint film becomes significant, and conversely, as the temperature rises above 50°C, film forming properties deteriorate and the compatibility of the wax component in the film decreases, making it difficult to maintain a sufficient paint film. Performance becomes unpredictable. Another component of the composition of the present invention, which has a melting point of 50
The wax (B) within the range of ~100°C includes paraffin wax, microcrystalline wax, intermediate product wax, and the like. Here, if the melting point of the wax is less than 50°C, the wax will stand out on the surface of the resulting coating film,
Stain resistance decreases, and conversely, if the temperature exceeds 100°C, the compatibility of the wax itself deteriorates, resulting in a decrease in film forming properties, and sufficient coating performance cannot be expected. Furthermore, the amount of the wax (B) used should be within the range of 2 to 40% by weight based on the solid content of the aqueous dispersion (A), and if it is less than 2% by weight, it is insufficient. Water repellency cannot be obtained, and conversely, if the amount exceeds 40% by weight, the stability of the obtained aqueous dispersion composition will decrease, and the adhesion to the substrate will also decrease, and furthermore, it will be difficult to use as a paint. When used, pigment dispersibility deteriorates and color unevenness occurs. The method for adding and mixing this wax (B) to the aqueous dispersion (A) is as follows: (1) When emulsion copolymerizing the various monomers described above, add the wax (B) in advance to the aqueous dispersion (A).
(B) is emulsified with a surfactant, and the monomer is copolymerized therein; (2) In the emulsion copolymerization process, for example, when dropping the monomer, the monomer and wax ( (3) When using a monomer-soluble wax (B), the monomer is dissolved in the wax (B) in advance and polymerization is carried out. There are also methods such as (4) emulsion copolymerization of the monomers and then adding an emulsion of wax (B) to the resulting aqueous dispersion (A). However, methods (1), (2), and (3) are preferably useful. In addition, when using wax (B) that has been emulsified in advance, a commercially available wax emulsion can be used as it is, and the wax in the wax emulsion is within the above range defined in the present invention. Of course, any aqueous dispersion of the copolymer mentioned above can be used.
Needless to say, it is impossible to use particles in which the charge of the particles in (A) and the charge of the wax emulsion used conflict with each other, and this point should be kept in mind. Thus, the composition of the present invention comprises the above-mentioned copolymer and wax contained in the aqueous dispersion (A).
By selecting and combining with (B), it is possible to form a coating film that is highly compatible with wax (B) and has low bleeding, and has excellent water repellency, water resistance, and durability, as well as weather resistance and It provides a coating film with excellent stain resistance. When producing a paint using the aqueous dispersion composition of the present invention thus obtained, pigments or extender pigments may be directly added to the aqueous dispersion composition and kneaded and dispersed. A method may also be used in which a pigment or extender pigment is previously dispersed in water using a dispersant and water to prepare a pigment paste, and then the aqueous dispersion composition of the present invention is added to the pigment paste. In addition, various other compounding agents generally used in emulsion paints, such as wetting agents, thickeners, plasticizers, film-forming agents, antifoaming agents, preservatives, and antifungal agents, can all be used. . Furthermore, the aqueous dispersion composition of the present invention may be mixed with aggregates such as frame stones or sand, or may be made into a sand wall-like paint made by blending these aggregates with the above-mentioned emulsion paint. Yes, it is extremely useful. The above-mentioned various paints made of the aqueous dispersion composition of the present invention can be applied by any of the commonly used methods, such as brush coating, roller coating, spray coating, and dip coating. can. Next, the present invention will be specifically explained using examples. Hereinafter, all parts and percentages are based on weight unless otherwise specified. Example 1 In a stainless steel reaction vessel, 95 parts of deionized water and 50 parts of a 40% emulsion of paraffin wax (melting point 70°C) were added.
parts, 1.5 parts of sodium dodecylbenzenesulfonate,
Polyoxyethylene nonylphenyl ether
3.5 parts of ammonium persulfate and 0.5 parts of ammonium persulfate were charged, the temperature was raised to 75-80°C in a nitrogen stream, and 2-ethylhexyl acrylate (solubility at 25°C =
A mixture of 39 parts of 0.03%), 60 parts of methyl methacrylate, and 1 part of acrylic acid was added dropwise over 180 minutes to copolymerize, and then further heated at the same temperature for 30 minutes.
The copolymerization was completed by holding for a minute. Then cool to 30 °C and add 28% ammonia water 1.2
The pH was adjusted to 7.5 at the department. The aqueous dispersion composition obtained here has a non-volatile content of 50
%, viscosity 300 cps, and pH 7.4. Hereinafter, this will be abbreviated as "composition ()". The composition thus obtained () was applied onto a glass plate using a 3 mil applicator and heated at 80°C.
After forming a film by force drying for 30 minutes,
The film was left to stand for a period of time, and the water repellency and water resistance of this film were measured. The results are shown in Table 1. In addition, we made a paint according to the paint formulation listed in Table 2, then applied this paint to a slate board with a brush and dried it at room temperature for 7 days, then observed and measured the physical properties of the paint film, and the results are shown in Table 3. show. Example 2 A monomer consisting of 50 parts of "Veova 10" (vinyl ester of versatile acid, manufactured by Siel Chemical, Netherlands; solubility at 25°C = 0.17%), 30 parts of vinyl acetate, 19 parts of methyl methacrylate, and 1 part of acrylic acid was used. The same operation as in Example 1 was repeated except for using a polymer mixture. The aqueous dispersion composition obtained here has a non-volatile content.
It was 49.8%, viscosity 170cps, and PH7.5. Hereinafter, this will be abbreviated as "composition ()". The same operations as in Example 1 were repeated except for using this composition (), and the physical properties of the film and the physical properties of the coating film were observed and measured. The results are shown in Tables 1 and 3. Comparative Example 1 The same operation as in Example 1 was repeated except for using a monomer mixture consisting of 20 parts of "Beoba 10", 60 parts of vinyl acetate, 19 parts of methyl methacrylate, and 1 part of acrylic acid, and the nonvolatile content was 49.4%. ,viscosity
An aqueous dispersion composition of 85 cps and pH 7.6 was obtained. Hereinafter, this will be abbreviated as "composition (')". Example 1 except for using this composition (')
The same operations as above were repeated to observe and measure the physical properties of the film and the physical properties of the coating film. The results are shown in Tables 1 and 3.

【table】

[Table] Table 2 Paint formulation (for gloss paint) ``Taipeke R-630'' (Rutile type titanium oxide manufactured by Ishihara Sangyo Co., Ltd.) 275.0 parts ``Tamor 731'' (Pigment dispersant manufactured by Rohm & Haas Company, USA) ) 9.0〃 “Nougen EA-120” (nonionic surfactant manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 2.2〃 Ethylene glycol 50.0〃 “Nopco NEW” (antifoaming agent manufactured by Nopco Chemical Company, USA) 2.0〃 Water 105.0 〃 28% ammonia water 1.0 〃 3% of “Cellocise QP-4400” (Hydroxyethyl cellulose manufactured by Union Carbide, USA)
Aqueous solution 12.5〃 Colloid mill dispersion 50% aqueous dispersion composition 616.5〃 3% aqueous solution of “Cellocise QP-4400” 37.5〃 “Texanol” (membrane aid manufactured by Kodatsu, USA)
24.7〃Water 35.0〃Total 1170.4〃 Pigment volume concentration 20% Non-volatile content 50.3%

【table】

[Table] Example 3 95 parts of deionized water was charged into a stainless steel reactor, and sodium dodecylbenzenesulfonate was added.
1.5 parts of polyoxyethylene nonyl phenyl ether, 3.5 parts of ammonium persulfate, and 0.5 parts of ammonium persulfate were dissolved, heated to 75-80°C in a nitrogen stream, and
10'', 30 parts of vinyl acetate, 19 parts of methyl methacrylate, and 1 part of acrylic acid, and 80 parts of a 40% emulsion of paraffin wax (melting point 70°C) were mixed over 180 minutes. After polymerization was carried out by dropping the mixture in parallel, the same temperature was further maintained for 3 minutes to complete the polymerization. Then, cool to 30 °C and add 28% ammonia water.
The pH was adjusted to 7.5 with 1.2 parts. The resulting aqueous dispersion composition had a non-volatile content of 50.5%;
The viscosity was 300 cps and the pH was 7.6. Hereinafter, this will be referred to as "composition ()". Regarding this composition (), the physical properties of the film and the coating film were tested in the same manner as in Example 1.
The results are shown in Table 4, with excellent water repellency,
It had water resistance. Comparative Example 2 An aqueous dispersion was prepared by repeating the same operation as in Example 3, except that the composition of the monomer mixture was changed to 50 parts of "Beoba 10", 30 parts of vinyl acetate, 10 parts of methyl methacrylate, and 10 parts of acrylic acid. A composition (') was obtained. The composition (′) thus obtained has a non-volatile content.
It was 50.1%, viscosity 3230cps, and PH6.9. Regarding this composition ('), the physical properties of the film and the coating film were tested in the same manner as in Example 1. The results are shown in Table 4, and the water repellency, water resistance, and stability of the paint were significantly reduced due to the large amount of acid groups.

[Table] Example 4 and Comparative Examples 3 and 4 Three types of aqueous dispersion compositions () were prepared by repeating the same operation as in Example 3, except that the composition of the monomer mixture was changed as shown in Table 5. , ('-1) and ('-2) were obtained. The property values of each dispersion composition are shown in Table 5. When the same operations as in Example 1 were repeated using these three types of compositions, the results of various physical properties of the film and paint film as shown in Table 6 were obtained, and after three months of outdoor exposure. As a result, the results of weather resistance and stain resistance as shown in the same table were obtained, but this shows that copolymers with a low glass transition temperature have poor water repellency and water resistance, as well as poor stain resistance. On the contrary, it is known that water repellency and water resistance are poor even when the glass transition temperature is too high.

【table】

[Table] Example 5 and Comparative Examples 5, 6, 7 and 8 475 parts of deionized water was charged into a stainless steel reaction vessel, and sodium dodecylbenzenesulfonate was added.
7.5 parts of polyoxyethylene nonyl phenyl ether, 17.5 parts of ammonium persulfate, and 2.5 parts of ammonium persulfate were dissolved and heated to 75 to 80°C in a nitrogen stream, and 150 parts of styrene and 2-ethylhexyl acrylate were dissolved therein.
A monomer mixture consisting of 150 parts of methyl methacrylate, 116 parts of ethyl acrylate, 40 parts of ethyl acrylate, and 4 parts of acrylic acid was added dropwise over 180 minutes to polymerize, and then maintained at the same temperature for an additional 30 minutes to complete the polymerization. I forced it. Then, cool to 30℃ and add 28% ammonia water.
The pH was adjusted to 8.0 with 20 parts. Thereafter, the aqueous dispersion thus obtained was divided into five parts, each containing (1) 40% of the wax with a melting point of 70°C;
50 parts of emulsion (Example 5), (2) 11 parts of deionized water (Comparative Example 5), (3) 45% emulsion of wax with a melting point of 70°C
111 parts (Comparative Example 6), (4) 40 parts of wax with a melting point of 20°C
(Comparative Example 7) and (5) 50 parts of a 40% emulsion of wax with a melting point of 150°C (Comparative Example 8) were added with stirring at room temperature to prepare five aqueous dispersion compositions ( ), ('-1), ('-2), ('-3) and ('-4) were obtained. Table 7 shows the resin constants of each of these compositions. The thus obtained compositions (), ('-1),
By repeating the same operation as in Example 1 using ('-2), ('-3), and ('-4),
The condition of each film was observed, and the water repellency and water resistance of the film were measured. The results are shown in Table 8. In addition, a paint was prepared according to the paint formulation listed in Table 2 above, and then this paint was used in Example 1.
After repeating the same operation as above, the physical properties of the coating film as shown in Table 9 were observed and measured.

【table】

【table】

[Table] Example 6 An aqueous dispersion composition and a paint were obtained in the same manner as in Example 1, except that the types of monomers in Example 1 were changed as shown below. The physical properties of the film and paint formed by the aqueous dispersion composition are shown below.

【table】

[Table] Water repellency after immersion ◎
Example 7 In Example 3, paraffin wax (melting point
An aqueous dispersion composition and a paint were obtained by replacing 50 parts of a 40% emulsion of paraffin wax (melting point 90°C) with 25 parts of a 40% emulsion of paraffin wax (melting point 90°C). The physical properties of the film and paint formed by the aqueous dispersion composition are shown below.

[Table] Water repellency after immersion ◎
Example 8 Example 4 was carried out by changing the type and amount of monomer used as shown below to obtain an aqueous dispersion composition and a paint. The physical properties of the film and paint formed by the aqueous dispersion composition are shown below.

【table】

[Table] Water repellency after immersion ◎
Example 9 In Example 1, the type and amount of monomer used and the amount of 28% ammonia water used were changed as shown below to obtain an aqueous dispersion composition and a paint. The physical properties of the film formed by the aqueous dispersion composition are shown below. The film of the aqueous dispersion composition was applied to a glass plate using a 3 mil applicator and heated at 80°C.
It was obtained by drying for 20 minutes and then baking at 140°C for 20 minutes.

【table】

Claims (1)

[Claims] 1 Solubility in water at 25℃ is 0.3% by weight
Copolymerized with 30% by weight or more of the following hydrophobic α/β-monoethylenically unsaturated monomer and 0.1 to 5% by weight of α/β-monoethylenically unsaturated carboxylic acid, and with a functional group A copolymer with a glass transition temperature of 0 to 50°C obtained by emulsion copolymerization of a monomer mixture consisting of 0 to 70% by weight of other α/β-monoethylenically unsaturated monomers that do not contain aqueous dispersion
Water repellency and water resistance of a coating film comprising (A) containing wax (B) with a melting point of 50 to 100°C within a range of 2 to 40% by weight based on the solid content of the dispersion (A). and aqueous dispersion compositions for coatings with excellent durability, weather resistance, and stain resistance.