JPH09235507A - Resin composition for cross-linking type water-based coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for a cross-linked type water-based coating material, good in storage stability of the coating material and capable of forming the coating film excellent in water and weather resistances, film- forming properties and gloss retention and especially excellent in stain resistance. SOLUTION: This resin composition for cross-linking type water-based coating material comprises (1) 100 pts.wt. acrylic aqueous resin emulsion containing 0.3-10 pts.wt. silicone-based macromonomer, 2-10 pts.wt. ketone group-containing monomer and 0-10 pts.wt. polyfunctional cross-linking monomer based on 100 pts.wt. acrylic monomer and (2) a water-soluble compound having at least >=2 hydrazide groups based on one molecule at a ratio so as to provide 0.3-2mol hydrazide groups based on 1mol ketone group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-pack type crosslinkable resin composition for water-based paints, and more specifically, it has excellent film-forming properties and excellent water resistance and weather resistance. The present invention relates to a resin composition for cross-linking type water-based paints capable of forming a film having excellent stain resistance against urban pollution which is said to be caused by soot and dust.

[0002]

2. Description of the Related Art In recent years, paints used on the interior and exterior walls of buildings and building materials contain a large amount of organic solvents under the circumstances of amendment of the Fire Defense Law to prevent fire hazards and strengthening of various pollution regulations. In addition to being increasingly shunned, paints containing a large amount of organic solvents are restricted in that they cannot be used in residential areas due to their odor, and the demand for water-based products is increasing more than ever. Aqueous emulsion paint is water-based, non-polluting, safe with no risk of fire, and has no problem of working environment pollution or odor caused by solvent vapor even when installed in a small indoor space or a dense residential area. However, there is an advantage in that it is possible to switch from the solvent system, but the conventional water-based resin was inferior to the solvent-based resin in terms of coating film performance in terms of water resistance and weather resistance.

As a method for solving this problem, it is considered that a ketone group- or aldehyde group-containing acrylic emulsion is formed into a crosslinked coating film with a polyhydrazide compound, and these are known as crosslinked water-dispersed resin compositions (special features JP-A-54-110248, JP-A-144432, JP-A-55-147562, JP-A-57-3857, JP-A-60-38468, JP-A-62-72742, and JP-A-2-138376. Japanese Patent Laid-Open No. 4-249587,
JP-A-7-62188). These combinations are
Although a crosslinked and water-resistant coating film can be formed, the stain resistance was not sufficient.

Therefore, for the purpose of improving the stain resistance, a method of adding a specific silicone compound such as silicone oil has been proposed. However, the silicone oil itself has water / oil repellency, stain resistance, and low abrasion. Since it has unique properties such as properties, the addition of a silicone compound can improve the water resistance and weather resistance of the coating film to some extent, but due to the high water and oil repellency of the silicone compound. , It is difficult to disperse the silicone compound uniformly in the resin in water, and even if it can be uniformly distributed in the emulsion particles, in the coating film made from the emulsion, the silicone compound makes the resin It was difficult to obtain a uniform coating film by separating from the above.

[0005]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks and has excellent film-forming properties, water resistance, and weather resistance which are not inferior to the coating performance of solvent-based resins, and is water-based. It is an object of the present invention to provide a resin composition which is a resin and is excellent in water resistance and weather resistance, and in particular, a resin composition for a crosslinkable water-based coating which is suitable for exterior building applications where stain resistance is required.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the acrylic monomer 1
0.3 parts by weight of silicone-based macromonomer to 100 parts by weight
10 to 10 parts by weight, a ketone group-containing monomer 2 to 10 parts by weight,
100 parts by weight of an acrylic aqueous resin emulsion containing 0 to 10 parts by weight of a polyfunctional crosslinking monomer and a water-soluble compound having at least 2 or more carboxylic acid hydrazide groups per molecule, wherein the hydrazide group is 1 The inventors have found that a resin composition for a crosslinkable water-based coating composition, which is contained at a ratio of 0.3 to 2 moles with respect to the moles, can solve the above-mentioned problems and has reached the present invention.

The silicone-based macromonomer used in the present invention is a general term for high molecular weight monomers having a radically polymerizable group at the terminal and having a polysiloxane structure, and the molecular weight is generally about 1,000 to 10,000. The terminal polymerizable group is preferably an acrylic group or a methacrylic group from the viewpoint of ease of copolymerization with the (meth) acrylic monomer used in the present invention, for example, a silicone macromonomer having a methacrylic group at one terminal. FM0711, FM0
721, FM0725 [manufactured by Chisso Co., Ltd.] and the like can be preferably used, and this is sufficient for the purpose of the present invention.
Hereinafter, this will be mainly described.

The amount of the silicone macromonomer used in the present invention must be in the range of 0.3 to 10 parts by weight with respect to 100 parts by weight of the acrylic monomer. If the amount used is less than 0.3 parts by weight, the effect of improving the weather resistance by using the silicone macromonomer as a constituent component is small, and conversely if it is more than 10 parts by weight, it is a copolymerizable macromonomer. Even so, unreacted macromonomer remains, and the polymer component rich in silicone component tends to separate from the emulsion. The emulsion having such a composition has not only poor polymerization stability, but also a coating film made from a paint produced by using this emulsion becomes non-uniform, and an adhesive layer formed by unreacted macromonomer is not formed. As a result of causing contamination or not forming a robust coating film in a portion having too much silicone component, it tends to be difficult to obtain a coating film excellent in weather resistance and water resistance, which is not preferable.

When a radically polymerizable silicone-based macromonomer, which is a component of the present invention, is used as a copolymerization component, the silicone component is copolymerized with an acrylic-based monomer to make macroscopically uniform inside the emulsion particles. Since it is distributed, the silicone compound can be uniformly distributed macroscopically in the coating film. In addition, by using a block / graft copolymer of an acrylic monomer and a silicone macromonomer, phase separation can occur microscopically and the properties of each segment component can be expressed simultaneously. The phenomenon that the silicone component is separated and a uniform coating film cannot be obtained, which is observed when the above ingredients are added, is eliminated.

The ketone group-containing monomer used in the present invention is a carbonyl group-containing compound having at least one ketone group and one polymerizable double bond in the molecule, and an ester group (-COO- ), A carboxyl group (-C
OOH) only compounds are excluded, and specific examples of such a ketone group-containing monomer include acrolein, diacetone (meth) acrylamide, diacetone methacrylamide, morphylstyrene, acetoacetoxyethyl methacrylate, 4 to 7 Vinyl alkyl ketones having carbon atoms, for example vinyl methyl ketone,
Examples thereof include vinyl ethyl ketone and vinyl butyl ketone, and diacetone (meth) acrylamide is particularly preferable.

In the present invention, it is necessary that the monomer containing a ketone group is used in an amount of 2 to 10 parts by weight based on 100 parts by weight of the acrylic monomer. 2 monomers containing ketone groups
If it is less than 10 parts by weight, the above-mentioned performance improvement of the coating film due to crosslinking is small, and conversely, if the amount of hydrophilic ketone groups is more than 10 parts by weight, the hydrophilicity of the polymer itself becomes too large. It is not preferable to use it because it tends to deteriorate its properties.

In the present invention, the crosslinking is a water-soluble compound having a ketone group derived from a monomer containing a ketone group incorporated in the emulsion particles and at least two carboxylic acid hydrazide groups per molecule dissolved / blended in water. The compound
Carboxylic acid hydrazide groups are contained in a proportion of 0.3 to 2 mol per 1 mol of ketone groups, and the reaction is carried out after water is volatilized after coating. As the hydrazide compound having at least two hydrazine residues per molecule used as a cross-linking agent, a dihydrazide compound represented by the following general formula (1) and / or a polymer having a carboxylic acid ester group is hydrazine or hydrazine water. Examples thereof include dihydrazide compounds produced by reacting with a compound (that is, hydrazine hydrate). H ₂ N-NH-CO- (CH ₂ ) n-CO-NH-NH ₂ (n ≦ 8) (1)

Specific examples of the compound having at least two hydrazide groups per molecule include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide and itaconic acid. Examples thereof include dihydrazide. Also, an aliphatic water-soluble dihydrazine having 2 to 4 carbon atoms, for example, ethylene-
1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine and the like can also be used. These may be used in combination of two or more. Further, depending on the film-forming auxiliary used in the paint, there are those that increase the solubility of these hydrazide compounds, and it is also possible to use hydrazide compounds which are substantially dissolved in the emulsion paint by these.

In the present invention, the proportion of the hydrazide compound dissolved in the aqueous phase is such that the carboxylic acid hydrazide group is
Ketone group 1 contained in acrylic aqueous resin emulsion
The molar ratio is preferably 0.3 to 2 with respect to the mol. When the molar ratio of the carboxylic acid hydrazide group is less than 0.3 with respect to the ketone group contained in the polymer, the performance improvement of the coating film due to crosslinking is small, and when the molar ratio is more than 2, the water-soluble hydrazide compounded excessively. After the coating film is formed, the compound is extracted with water due to rainfall or the like, and the water resistance of the coating film deteriorates.

The acrylic monomer, which is the main component of the resin composition for a crosslinkable water-based coating composition of the present invention, is a basic performance for forming a coating film, namely, coating workability, drying property, coating film hardness and resistance. Solvent resistance, weather resistance, a component effective in improving water resistance, etc., can be appropriately selected according to the performance required for the coating film,
Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, ter.
alkyl or cycloalkyl ester of (meth) acrylic acid such as t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and the like Hydroxy group-containing monomer; α, β-ethylenically unsaturated carboxylic acid such as (meth) acrylic acid, maleic acid, fumaric acid and the like can be mentioned. Further, a part of the (meth) acrylic monomer used in the present invention may be replaced with a styrene monomer such as styrene and vinyltoluene, but the ratio is preferably 30 parts by weight or less, and more than this. If so, the weather resistance tends to be inferior, so use is not preferable.

In the present invention, a polyfunctional crosslinking monomer may be used to further crosslink the inside of the emulsion particles. However, if the inside of the emulsion particles is cross-linked too highly, the emulsion particles will not dissolve even with the film-forming aid, resulting in poor film formation. Therefore, the cross-linking inside the emulsion particles must be suppressed to an appropriate degree. Therefore, it is preferable to use 0 to 10 parts by weight of the acrylic monomer during the polymerization in order to crosslink the inside of the emulsion particles. Specific examples of such a polyfunctional crosslinkable monomer include divinylbenzene and ethylene glycol diester. Methacrylate, 1,3-butylene dimethacrylate, allyl methacrylate and the like can be exemplified.

The Tg of the coating film obtained from the crosslinkable aqueous resin composition of the present invention is preferably in the range of 20 to 65 ° C. If the Tg is lower than 20 ° C, cross-linking the coating has little effect on the stain resistance, and if the Tg is higher than 65 ° C, not only the film formation becomes difficult, but also the coating becomes too hard. It is not preferable because it does not follow the slight deformation of the coating material and the adhesion is lowered, or the impact resistance becomes poor and the formed coating film is easily cracked. Tg of the coating film of the present invention
Is a value measured by Rheovibron manufactured by Orientec Co., Ltd.

The method for producing the acrylic copolymer aqueous resin emulsion of the present invention may be a usual emulsion polymerization method, such as distilled water, a monomer mixture, a surfactant, a chain transfer agent (polymerization degree modifier), a radical polymerization initiator. The basic composition of the surfactant is a fatty acid soap, an alkyl sulfonate, an alkyl benzene sulfonate, an alkyl sulfosuccinate, an anionic surfactant such as polyoxyethylene alkyl sulfate, a polyoxyethylene alkyl ether, and a polyoxyethylene alkyl ether. Nonionic surfactants such as oxyalkyl aryl ethers and polyoxyethylene sorbitan fatty acid esters can be mentioned, and they are usually used as an anionic surfactant alone or in a mixed system with a nonionic surfactant. 0.01 to 5% by weight is common.

Examples of the chain transfer agent include mercaptans such as n-dodecyl mercaptan and mercaptoethanol, and halogenated hydrocarbons such as carbon tetrachloride. Radical polymerization initiators include persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate, hydrogen peroxide, t
Examples include peroxides such as -butyl hydroperoxide and cumene hydroperoxide, and azobis compounds such as 2,2-azobisisobutyronitrile, with persulfate being most preferred. The polymerization temperature is usually 60-9.
The range of 0 ° C. is generally used, but redox polymerization in which a reducing agent such as sodium bisulfite, Rongalit, and ascorbic acid (salt) is combined with a radical polymerization initiator can also be used.

The water-based resin composition of the present invention can be applied as it is as a clear varnish which is the above-mentioned composition, and is appropriately used as a brightening agent such as aluminum paste, a pigment such as titanium oxide, or an inorganic coloring agent such as talc. Blended with various known paint additives such as extender pigments, matting agents such as silica, dispersants, anti-sagging agents, antifoaming agents, film-forming aids, antifreezing agents, plasticizers, and ultraviolet absorbers. Good. In addition, a room temperature crosslinkable polyurethane emulsion or acrylic resin emulsion, or another aqueous emulsion that does not impair the crosslinkability can be added to the water-based resin composition of the present invention within a range that does not impair the original performance.

As the base material to which the resin composition for cross-linking type water-based coating composition of the present invention is applied, concrete, slate, ALC, wood, metal and the like used for building wall materials and building materials are suitable. However, it can also be applied to other plastics. When coating these substrates, the coating method is not particularly limited, and various known methods such as spraying and brush coating may be adopted.

[0022]

EXAMPLES Next, the present invention will be specifically described with reference to Reference Examples, Examples and Comparative Examples, but the following is an example and the present invention is not limited to these Examples. In addition, "part" in each example means a "weight part."

Reference Example 1 (Synthesis Example of Acrylic Aqueous Resin Emulsion of the Present Invention) Methyl methacrylate 54 parts, 2-ethylhexyl acrylate 15 parts, butyl acrylate 14.5 parts, 2-hydroxyethyl methacrylate 5 parts, 5 parts of diacetone acrylamide, 1 part of acrylic acid, 5 parts of diester of methacrylic acid and propylene glycol 9-mer, FM0721
0.5 parts of Chisso Co., Ltd. and 1 part of Emulgen 408 [Kao Co., Ltd.] were dissolved, 0.1 parts of ammonium persulfate, 123 g of water, and 2 parts of sodium lauryl sulfate as an emulsifier were dissolved. The dissolved product was added, and the mixture was stirred with a homomixer manufactured by Tokushu Kika Co., Ltd. at a sales expansion rate of 13000 rpm for 6 minutes to prepare a pre-emulsion. A four-necked flask equipped with a spreader, a reflux condenser, a nitrogen introduction tube, and a dropping funnel was placed in a constant temperature water bath at 80 ° C., and the pre-emulsion was added dropwise for 4 hours to continue the reaction. After keeping the temperature at 2 ° C. for 2 hours, it was cooled and neutralized with 28% aqueous ammonia to obtain an acrylic aqueous resin emulsion having a nonvolatile content of 45.9%.

Reference Examples 2-5. The monomer composition is shown in Table 1 below.
An acrylic aqueous resin emulsion was obtained in the same manner as in Reference Example 1, except that the acrylic water-based resin emulsion was changed as shown in FIG.

Reference Examples A to I. (Synthesis Example of Acrylic Aqueous Resin Emulsion Used in Comparative Example) An acrylic aqueous resin emulsion was obtained in the same manner as in Reference Example 1 except that the monomer composition was changed as shown in Table 2 below.

[0026]

[Table 1]

[0027]

[Table 2]

Examples 1-5 and Comparative Examples 1-8. Reference Example 1
.About.5 and the acrylic aqueous resin emulsions obtained in A to I were used to prepare a resin composition for a crosslinkable aqueous coating material as follows. (1) Preparation of pigment paste. Titanium oxide, Taipaque R
-930 [Ishihara Sangyo Co., Ltd.] 100 parts, methyl cellulose [Shin-Etsu Chemical Co., Ltd. Hi-Metroze 90
SH-15000], 0.6 part, polycarboxylic acid type dispersant [Rohm and Haas, Primal 850]
1 part, 5% potassium tripolyphosphate 2 parts, surfactant [Nippon Industrial Chemical Co., Ltd., Neugen EA-120]
1 part, antifoaming agent [Adekanol SX manufactured by Asahi Denka Co., Ltd.
-568], 2.5 parts, ethylene glycol 10 parts,
35.2 parts of water and 1 part of 28% ammonia water were mixed and dispersed in a high speed disperser to prepare a pigment paste.

(2) Preparation of resin composition for crosslinkable water-based coating. 71.7 parts of the acrylic aqueous resin emulsions obtained in Reference Examples 1 to 5 and AI, 39.4 parts of the pigment paste prepared in (1) above, and a defoaming agent [manufactured by Asahi Denka Co., Ltd., [Adecanate B1016] 0.2 part, a film-forming aid [manufactured by Nippon Emulsifier Co., Ltd., DBDG] 7.9 parts are blended, and adipic acid dihydrazide as a crosslinking agent is a ketone contained in each acrylic aqueous resin emulsion. After adding the same amount as the base, the mixture was mixed and dispersed with a paint shaker for 20 minutes. The viscosity of each of the obtained coating materials was adjusted with water using a NO4 Ford cup at 30 seconds / 20 ° C to prepare water-based coating materials of Examples 1-5 and Comparative Examples 1-8.

(3) Preparation of test plate An aluminum plate (150 x 300 mm) was coated with an undercoat paint [Ceramitone primer manufactured by Fujikura Kasei Co., Ltd.] in a dry film thickness of 20 µm and dried at 70 ° C for 30 minutes. The thing was used as a test plate for evaluation. The coating on the test plate was carried out by spray-coating each of the aqueous paints prepared in (2) above to a dry film thickness of 30 μm, then leaving it at room temperature for 30 minutes, and then again to a dry film thickness of 30 μm. After spray-coating, drying at 70 ° C. for 30 minutes, and leaving it at room temperature for 1 week was used for evaluation. After drying the test plate, warm it to about 50 ° C and put 1 at 80 mm from the edge.
Bend at an obtuse angle of 35 degrees, and at the time of the exposure test, collect dirt and rainwater at the bent portion at an angle of 135 degrees above the vertically fixed test plate and let it flow down onto the vertically fixed test plate. went.

"Evaluation Results" The water-based coating composition obtained in (2) above was evaluated for the following items.
The evaluation results are summarized in Table 3. 1. Paint stability: × when the silicone component separated and formed a transparent oil layer that could not be made into a paint, Δ when separation was slight and could be made into a paint, and when the oil layer did not separate ○
Was evaluated. 2. Film-forming property: When the test plate was prepared, it was spray-painted and immediately transferred to a thermostatic chamber at 10 ° C. to dry the test plate. The film-forming property of a coating material that forms a continuous coating film after drying was evaluated as ◯, and that which does not form a continuous coating film was evaluated as x. 3. Rain stain resistance: Rain stain resistance was evaluated by exposing the test plate shown above. The exposed area is Itabashi-ku, Tokyo, and the exposure was started on August 1, 1995, and evaluated 3 days later on 22nd.
In the evaluation, those in which rain spots could not be confirmed were rated as O, those that were slightly visible were rated as Δ, and those that were clearly visible were rated as X. 4. Tg (glass transition point) measurement: glass transition point T of coating film
The value g was measured using Rheovibron manufactured by Orientec Co., Ltd. In addition, Tg is about 5 in terms of dry film thickness.
After spray coating on a test plate made of mild steel so as to be 0 μm, it was dried under reduced pressure at 80 ° C. for 24 hours to remove volatile components to some extent and then measured.

5. Gloss retention (weather resistance evaluation): The weather resistance was measured by cutting the above aluminum test plate into a size of 50 × 50 mm, measuring the 60 degree gloss before and after applying it to a sunshine weatherometer for 1000 hours, and maintaining the retention rate of 80. % Or more. Those smaller than that were evaluated as x. 6. Water resistance evaluation: The water resistance of the emulsion resins themselves used in Examples and Comparative Examples was evaluated by the degree of whitening when the clear coating film was immersed in water. The sample is emulsion 71.
7 parts, 2 parts water, Dowanol TPNB manufactured by Dow Chemical Company
To 7.9 parts, a clear paint containing a ketone group and an equivalent amount of carboxylic acid hydrazide was coated on a release paper to a thickness of about 50 μm, and the haze value before and after soaking in warm water at 50 ° C. for 3 hours was adjusted. When the haze value change was less than 3, the whiteness was judged to be small, and the haze value change was 3 or more.
Those with less than were judged as Δ, and those with more than were judged as ×.

[0033]

[Table 3]

[0034]

EFFECTS OF THE INVENTION As can be seen from Table 3, the resin composition for crosslinkable water-based coating composition of the present invention is more stable than the compositions (Comparative Examples 1 to 8) not satisfying the requirements of the present invention. It can be seen that a resin composition for coating having a well-balanced and outstandingly excellent film forming property, rain spot resistance (contamination resistance), weather resistance, and water resistance can be obtained.

Claims (2)

[Claims] (1) 0.3 to 10 parts by weight of a silicone-based macromonomer, 2 to 10 parts by weight of a ketone group-containing monomer, and 0 to 10 parts by weight of a polyfunctional crosslinking monomer, relative to 100 parts by weight of an acrylic monomer. 100 parts by weight of the acrylic aqueous resin emulsion contained, and (2) a water-soluble compound having at least two hydrazide groups per molecule, the hydrazide group being 0.
A resin composition for cross-linked water-based paint, characterized in that it is contained in a proportion of 3 to 2 mol. (1) 0.3 to 10 parts by weight of a silicone-based macromonomer, 2 to 10 parts by weight of a ketone group-containing monomer, and 0 to 10 parts by weight of a polyfunctional crosslinking monomer, relative to 100 parts by weight of an acrylic monomer. 100 parts by weight of the acrylic aqueous resin emulsion contained, and (2) a water-soluble compound having at least two hydrazide groups per molecule, the hydrazide group being 0.
It is contained in a ratio of 3 to 2 mol, and the above (1)
And the glass transition temperature (T
g) is 20 to 65 ° C., which is a resin composition for cross-linkable water-based paints suitable for building exterior applications.