JPH0433824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous dispersion composition useful for coatings, and more particularly, it is composed of an aqueous dispersion of a specific emulsifying copolymer, a wax having a specific melting point, and colloidal silica. , relates to an aqueous dispersion composition for dyes having excellent water repellency and stain resistance. BACKGROUND ART Aqueous dispersions have traditionally been used in large quantities as paints due to their ease of handling, coating workability, and coating performance. Furthermore, although the original purpose of paint is to protect and beautify the base material, even higher weather resistance is required when it is used for external painting. In order to achieve this requirement, a paint with good water repellency against rainwater and stain resistance against dust is required, but conventional aqueous dispersions do not have sufficient water repellency or water resistance.
It also did not have excellent stain resistance. In order to improve water resistance, water repellents are sometimes added to paints, but although the addition of such water repellents is effective in imparting initial water repellency, water repellency is No effect was observed on the continuation of the condition. Furthermore, no measures have been found to improve stain resistance. In order to overcome these drawbacks, the present inventors have proposed a paint dispersion composition comprising an aqueous dispersion of a specific emulsion copolymer and a wax having a specific melting point range. They discovered that the composite had excellent weather resistance and proposed the use of the composite as an aqueous dispersion composition for paints (Japanese Patent Laid-Open No. 71747/1983). However, although the above-mentioned aqueous dispersion composition for paints has practically satisfactory performance, it does not provide sufficient performance in terms of stain resistance after long-term exposure, and there is still room for further improvement. was left behind. Therefore, the present inventors conducted research to further improve the composition, and found that by adding a specific amount of colloidal silica to the aqueous dispersion composition for paint, water repellency, water resistance, and weather resistance could be impaired. However, the present inventors have discovered that the stain resistance is dramatically improved, and have completed the present invention. That is, the present invention comprises 30% by weight or more of a hydrophobic monoethylenically unsaturated monomer whose solubility in water at 25°C is 0.3% by weight or less, and other monoethylenically unsaturated monomers that can be copolymerized with the hydrophobic monoethylenically unsaturated monomer. A mixture of monomers consisting of 0 to 70% by weight of the monomer and 0.1 to 5% by weight of α,β-monoethylenically unsaturated carboxylic acid,
A wax having a melting point of 50 to 100°C is added to the aqueous dispersion (A) obtained by emulsion copolymerization within a range of 2 to 40% by weight (in terms of solid content) based on the solid content of the dispersion (A). (B) and colloidal silica (C) within a range of 1 to 200% by weight (solid content), which is extremely practical and has excellent water repellency and stain resistance of the coating film. The present invention aims to provide an aqueous dispersion composition for paint with high properties. Here, the above-mentioned "monoethylenically unsaturated monomer" refers to a monomer having one polymerizable carbon-carbon double bond. The above-mentioned "hydrophobic 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 is:
Referring to those having a solubility in water at 25°C of 0.3% by weight or less, preferably 0.1% by weight or less, only particularly representative hydrophobic monomers are exemplified. Various (meth)acrylic acid esters such as butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate or stearyl methacrylate; such as styrene or α-methylstyrene;
Various aromatic vinyl monomers; various α-olefins or halogenated olefins ((halogen-substituted) olefins) such as ethylene, vinyl chloride, or vinylidene chloride; or various carboxylates such as vinyl versatate; acid vinyl esters, etc., but of course these can be used alone or in combination of two or more types, and the hydrophobic monomer needs to be used in an amount of 30% or more by weight based on the total amount of monomers. There is. Next, examples of other monoethylenically unsaturated monomers that can be copolymerized with such hydrophobic monomers include methyl acrylate, ethyl acrylate, and methyl methacrylate. Various esters of (meth)acrylic acid and monohydric alcohols, such as; or vinyl acetate or "Beoba" (vinyl esters of branched aliphatic monocarboxylic acids, manufactured by Siel, Netherlands)
and various vinyl carboxylic acid esters such as; It may be used in an amount up to 70% by weight. 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 copolymer composition ratio of the above-mentioned hydrophobic monomer is less than 30% by weight, the water repellency and water resistance of the film formed by the resulting copolymer will inevitably decrease. Moreover, the durability of this water repellency becomes poor, which is not preferable. In addition, if other monoethylenically unsaturated monomers that can be copolymerized with the above-mentioned hydrophobic monomers are contained in a large amount exceeding 70% by weight in the total monomers,
The resulting copolymer has strong hydrophilicity, and the water repellency and water resistance of the formed film are reduced, and the durability of the 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 resulting aqueous copolymer dispersion decreases. , a good aqueous dispersion composition cannot be obtained, and conversely, if the amount exceeds 5% by weight in the total monomer, the viscosity of the copolymer aqueous dispersion will be significantly affected by the change in pH, making it difficult to coat. Workability deteriorates, and the film formed 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. Acrylamide, N-butoxymethylol acrylamide, N-butoxymethylol methacrylamide, diacetone acrylamide, glycidyl acrylate, glycidyl methacrylate,
Of course, it is also possible to copolymerize about 0.5 to 10% by weight of one or more of β-hydroxyethyl acrylate, β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, or γ-methacryloyloxypropyltrimethoxysilane. . The aqueous dispersion (A), which is the first component of the composition of the present invention, can be obtained by a conventional emulsion polymerization method. 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 surfactants can be used alone or in combination of two or more types, but it is usually preferable to use a combination of an anionic surfactant and a nonionic surfactant. 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 portions, 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 sufficient paint film performance. It becomes impossible to expect. The wax (B), which is the second component of the composition of the present invention and has a melting point within the range of 50 to 100°C, includes paraffin wax, microcrystalline wax, intermediate product wax, and the like. Ru. Here, if the melting point of the wax is less than 50℃, the wax will stand out on the surface of the resulting coating film, reducing stain resistance, and conversely, if it exceeds 100℃, the compatibility of the wax itself will deteriorate. As a result, film forming properties deteriorate, 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. If used, the pigment dispersibility will be poor and color unevenness will occur. 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), this wax (B) is dissolved in the monomer in advance and then polymerized. 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. Colloidal silica (C), which is the third component of the composition of the present invention, is an aqueous dispersion containing SiO ₂ as a basic unit, and includes those having a particle size of 4 to 100 mμ. The colloidal silica dispersion is
Either acidic or basic can be used, and can be appropriately selected depending on the conditions of addition and mixing with other constituent components (A) and (B) of the composition of the present invention. As the acidic dispersion of colloidal silica, for example, Snotex O or Snotex OL (manufactured by Nissan Chemical Industries, Ltd.) can be used. On the other hand, as a basic dispersion of colloidal silica,
For example, the trade names Snowtex 20, Snowtex 30, Snowtex 40, Snowtex C, and Snowtex N (manufactured by Nissan Chemical Industries, Ltd.) can be used. The amount of colloidal silica (C) used here is
It should be within the range of 1 to 200% by weight (in terms of solid content) based on the solid content of the aqueous dispersion (A), and 1
When the amount is less than 200% by weight, no significant improvement in stain resistance can be obtained, and on the other hand, when it is used in a large amount exceeding 200% by weight, the water repellency of the resulting aqueous dispersion composition is significantly reduced. Therefore, the desired high degree of weather resistance cannot be achieved. The method for adding and mixing this colloidal silica (C) to the aqueous dispersion (A) is as follows: (1) When emulsifying and copolymerizing the various monomers described above, colloidal silica (C) is added in advance. (2) In the emulsion copolymerization step, for example, when adding the monomer dropwise, the monomer and colloidal silica (C) are simultaneously added dropwise or Examples include a method of emulsion mixing and dropping, and a method of (3) adding colloidal silica (C) to the resulting aqueous dispersion (A) after emulsion copolymerization of monomers.
Either method may be used. In the present invention, the addition of wax (B) and colloidal silica (C) to the aqueous dispersion (A) is performed by adding methods (1) to (4) of the wax (B) and colloidal silica (C). It is generally carried out by a combination of addition methods (1) to (3), but when using wax (B) and colloidal silica (C) within the range defined in the present invention in the aqueous dispersion (A), Even if other addition methods are used, the effects of the present invention will not be impaired. Thus, the composition of the present invention has water repellency and resistance due to the combination of the aqueous dispersion (A) of a specific emulsion copolymer constituting the composition, the wax (B) having a specific melting point range, and the colloidal silica (C). It provides a coating film with excellent stain resistance and high weather resistance. Although it is not necessarily clear why the composition of the present invention can achieve the above effects by combining the constituent components (A), (B), and (C), the aqueous dispersion (A), When wax (B) and colloidal silica (C) are mixed, their compatibility becomes good, and a homogeneous sea-island structure is formed on the coating surface, resulting in the water repellency of the aqueous dispersion (A) and wax (B) This is probably because the hardness of colloidal silica (C), an inorganic polymer, is fully demonstrated. Furthermore, colloidal silica (C) also reacts with the OH groups present on the surface of the inorganic substrate and cross-links, thereby forming a strong organic and inorganic composite coating on the surface of the substrate. It is thought that it was possible to obtain a high degree of weather resistance that was previously unattainable. 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, it is also possible to use all of the other compounding agents commonly used in emulsion paints, such as wetting agents, thickeners, plasticizers, film-forming agents, antifoaming agents, preservatives, and antifungal agents. be. Furthermore, the aqueous dispersion composition of the present invention can be made into a sand wall-like paint by blending aggregates such as crushed stone or sand, or by blending these aggregates into the emulsion paint as described above. , extremely useful. The above-mentioned various paints made from 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. 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, 55 parts of deionized water,
40% emulsion of parfine wax (melting point 70℃)
50. Charge 100 parts of Snowtex 30 (30% colloidal silica aqueous dispersion), 1.5 parts of sodium dodecylbenzenesulfonate, 3.5 parts of polyoxyethylene nonyl phenyl ether, and 0.5 parts of ammonium persulfate, and heat at 75 to 80°C in a nitrogen stream. The temperature rose to . 2-ethylhexyl acrylate (25℃
A mixture consisting of 39 parts (solubility in water = 0.03%), 60 parts of methyl methacrylate, and 1 part of acrylic acid was added dropwise over 180 minutes to copolymerize, and then kept at the same temperature for an additional 30 minutes. Copolymerization was completed. Next, cool to 30℃ and PH with 28% ammonia water.
Adjusted to 7.5. The aqueous dispersion composition obtained here had a nonvolatile content of 50°C, a viscosity of 200 cps, and a pH of 7.5. This aqueous dispersion composition was made into a paint according to the paint formulation shown in Table 1, and then this paint was applied to a slate board with a brush and dried at room temperature for 7 days, after which the physical properties of the paint film were observed and measured. The results are shown in Table 2. Example 2 "Beoba 10" (Versatric acid vinyl ester manufactured by Ciel Chemical Co., Ltd.; solubility in water at 25°C =
The same procedure as in Example 1 was carried out, except that monomers consisting of 50 parts of vinyl acetate, 19 parts of methyl methacrylate, and 1 part of acrylic acid were used. The resulting aqueous dispersion composition had a nonvolatile content of 49.7%;
The viscosity was 130 cps and the pH was 7.5. The same operations as in Example 1 were repeated for this composition to observe and measure the physical properties of the coating film. The results are shown in Table 2. Example 3 In a stainless steel reaction vessel, 55 parts of deionized water was charged and sodium dodecylbenzenesulfonate was added.
1.5 parts of polyoxyethylene nonyl phenyl ether, 3.5 parts of polyoxyethylene nonyl phenyl ether, and 0.5 parts of ammonium persulfate were dissolved, and the temperature was raised to 75 to 80°C in a nitrogen stream. A monomer mixture consisting of 50 parts of "Beoba 10", 30 parts of vinyl acetate, 19 parts of methyl methacrylate and 1 part of acrylic acid, 50 parts of a 40% emulsion of paraffin wax (melting point 70°C), and 30 parts of Snowtex
(100 parts of colloidal silica 30% aqueous dispersion) was added dropwise in parallel to polymerize, and then the same temperature was further maintained for 30 minutes to complete the polymerization. The mixture was then cooled to 30°C, and the pH was adjusted to 7.5 with 28% aqueous ammonia.
The resulting aqueous dispersion composition had a nonvolatile content of 49.8%, a viscosity of 140 cps, and a pH of 7.5. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Example 4 The composition of the monomer mixture was changed to 30 parts of styrene (solubility at 25°C = 0.029%), 30 parts of 2-ethylhexyl acrylate, 29 parts of methyl methacrylate, 10 parts of ethyl acrylate, and 1 part of acrylic acid. Non-volatile content was 50.1 by the same operation as in Example 3.
%, a viscosity of 350 cps, and a pH of 7.5. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Example 5 In a stainless steel reaction vessel, 50 parts of deionized water was charged, and 1.5 parts of sodium dodecylbenzenesulfonate was added.
Part, polyoxyethylene nonyl phenyl ether
Dissolve 3.5 parts and 0.5 parts of ammonium persulfate,
The temperature was raised to 75-80°C in a nitrogen stream. A monomer mixture consisting of 30 parts of styrene, 30 parts of 2-ethylhexyl acrylate, 29 parts of methyl methacrylate, 10 parts of ethyl acrylate, and 1 part of acrylic acid was added thereto for 180 minutes to polymerize, and then further heated to the same temperature. The polymerization was maintained for 30 minutes to complete the polymerization. The mixture was then cooled to 30°C and adjusted to pH 8.0 with 28% aqueous ammonia. Afterwards, the obtained aqueous dispersion (solid content
100 parts) of a 40% emulsion of wax with a melting point of 70°C (50 parts)
and 100 parts of Snowtex 30 were added at room temperature with stirring to obtain a non-volatile content of 50.1%, a viscosity of 320 cps,
An aqueous dispersion composition with a pH of 8.1 was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Example 6 The same operation as in Example 5 was carried out except that 15 parts of Snowtex 30 (30% water medium of colloidal silica) was added as colloidal silica, and the nonvolatile content was 57.2
%, a viscosity of 4500 cps, and a pH of 8.1. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Example 7 The same operation as in Example 5 was carried out except that 500 parts of Snowtex 30 (30% colloidal silica aqueous dispersion) was added as colloidal silica, and the non-volatile content was
An aqueous dispersion composition of 40.1%, viscosity 30 cps, and PH 8.2 was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The second result is
Shown in the table. 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 50.0%. Viscosity 100cps,
An aqueous dispersion composition with a pH of 7.5 was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 2 The same operation as in Example 1 was repeated 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, and the nonvolatile content was 49.8 parts. %, viscosity 7000cps, PH
An aqueous dispersion composition of 6.5 was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 3 The same operation as in Example 5 was performed except that wax and colloidal silica were not added and 55 parts of deionized water was added, resulting in a nonvolatile content of 50.1%, viscosity of 300 cps, and pH of 8.0.
An aqueous dispersion composition was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 4 The same operation as in Example 5 was performed except that the amount of wax added was changed to 120 parts, and the nonvolatile content was 49.2% and the viscosity was
An aqueous dispersion composition of 320 cps and pH 8.0 was obtained. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 5 The same procedure as in Example 5 was carried out except that the type of wax was changed to one with a melting point of 20°C, and the nonvolatile content was 49.8
%, a viscosity of 300 cps, and a pH of 8.0. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 6 The same procedure as in Example 5 was carried out except that the type of wax was changed to one with a melting point of 150°C, and the non-volatile content was 50.0.
%, a viscosity of 290 cps, and a pH of 8.1. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative Example 7 The same operation as in Example 5 was performed except that 55 parts of deionized water was added without adding colloidal silica to obtain an aqueous dispersion composition having a nonvolatile content of 50.1%, a viscosity of 350 cps, and a pH of 8.1. This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured. The results are shown in Table 2. Comparative example 8 The type of colloidal silica was Snotex 40.
(Colloidal silica 40% aqueous dispersion) The same operation as in Example 5 was performed except that 625 parts of this was added to obtain an aqueous dispersion composition with a non-volatile content of 42.5%, a viscosity of 65 cps, and a pH of 8.1. . This composition was subjected to the same operations as in Example 1, and the physical properties of the coating film were observed and measured.
The results are shown in Table 2. Table 1 Paint formulation (for gloss paint) "Taipeke R-630" (rutile type titanium oxide manufactured by Ishihara Sangyo Co., Ltd.) 275.0 parts "Tamol 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〃 "Nobuco NDW" (antifoaming agent manufactured by Nobuco Chemical Company, USA) 2.0〃 Water 105.0〃 28% Ammonia water 1.0〃 3% aqueous solution of "Cellocise QP-4400" (Hydroxyethyl cellulose manufactured by Union Carbide, USA) ... Colloid mill dispersion ... 50% aqueous dispersion composition 616.5 parts 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]

Claims (1)

[Claims] 1 30% by weight or more of a hydrophobic monoethylenically unsaturated monomer whose solubility in water at a temperature of 25°C is 0.3% by weight or less, and other monoethylenically unsaturated monomers that can be copolymerized with it. 0 to 70% by weight of
An aqueous dispersion (A) obtained by emulsion polymerization of a monomer mixture consisting of 0.1 to 5% by weight of α,β-monoethylenic carboxylic acid is added to Wax (B) with a melting point of 50 to 100°C within the range of ~40% by weight (solid content equivalent) and 1 to 200% by weight
1. An aqueous dispersion composition for paint, characterized in that it contains colloidal silica (C) within a range of % by weight (based on solid content).