JPH0959568A - Coating composition and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating composition containing a reaction product of colloidal silica with an organic silicon compound and an emulsion of a cold- curing acrylic resin as main components and giving a coating film having excellent adhesiveness to various substrates, water resistance, heat resistance, etc. SOLUTION: The objective coating composition is composed mainly of (A) a reaction product produced by reacting (i) colloidal silica with (ii) an organic silicon compound of the formula ((x) is 0 or 1; R is an alkyl, vinyl, etc.; R<1> is an alkyl or phenyl; R<2> is a lower alkyl) (e.g. ethyltrimethoxysilane) in a solvent (preferably water) and (B) a cold-curing silicone acrylic resin emulsion. The ratio of the component (i) to the component (ii) is preferably 1:(100-0.2) and the amount of the component B is preferably 10-1,000 pts.wt. based on 100 pts.wt. of the solid content of the component A. Since the objective composition may cause hydrolysis reaction in an aqueous solution, the composition is preferably stabilized by adjusting the pH of the aqueous solution to 5-7 with a buffering agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating composition used for coating, surface protection of various substrates, strength reinforcement and the like. More specifically, the present invention is excellent in adhesiveness to inorganic substrates such as metal, mortar, concrete, and glass, and resins, wood, paper, organic substrates such as fibers, and hardness, transparency, and their surface. Water resistance, heat resistance, weather resistance,
The present invention relates to a coating composition for forming a coating film having excellent acid resistance and organic chemical resistance at room temperature, a method of using the same, and a substrate coated by the method.

[0002]

2. Description of the Related Art In recent years, materials such as paints and adhesives have been shifting from organic solvent-based materials to water-based materials such as emulsions and water-soluble resins from the viewpoints of pollution prevention, resource saving and health and safety. In particular, from the viewpoint of ease of use, research has been actively conducted on a reactive resin maergeon that can be used as a single liquid, particularly a silicone acrylic resin emulsion that can be cured at room temperature and moisture, and various products have been developed. However, the conventional silicone-acrylic resin emulsion keeps the stability of the product at room temperature low, so the amount of hydrolyzable groups that undergo cross-linking reaction is kept low, so the coating hardness and adhesion to various substrates are insufficient. There was a problem. In addition, since the conventional silicone acrylic resin emulsion forms a coating film by fusing the emulsion particles, there is a problem that the water resistance, acid resistance, and uniformity of the coating film obtained are insufficient. It was

On the other hand, molding materials such as plastics have been widely used as materials replacing glass and metal by taking advantage of their characteristics such as transparency, lightness and workability, but the surface has scratch resistance and chemical resistance. However, it was poor in weather resistance and required a surface hard coat treatment. Silicone-based and acrylic-based surface hard coating agents have been developed, but all of the water-based ones have a problem in that they have insufficient adhesion to resin, coating film hardness, and chemical resistance.

[0004]

DISCLOSURE OF THE INVENTION The present invention is a coating composition intended to solve the above-mentioned drawbacks, which is stable in water, and metal, and inorganic groups such as cement, mortar, concrete and glass. Create a coating film with excellent adhesiveness, water resistance, heat resistance, weather resistance, acid resistance, organic chemical resistance, and abrasion resistance on the surface of organic base materials such as wood, plastic, wood, paper, and fibers. Another object of the present invention is to provide a coating composition capable of forming a film at room temperature or with slight heating.

[0005]

Means for Solving the Problems As a result of testing many low molecular weight compounds and high molecular weight compounds and combinations thereof, the present inventors have found that a room temperature curable silicone acrylic resin emulsion and A compound containing the reaction product of colloidal silica and an organic silicon compound disclosed in JP-A-3-8745 as a scratch-shielding agent for a glass container is stable in water and has room-temperature curability, water resistance, heat resistance, and weather resistance. The inventors have found that a coating film having excellent acid resistance, organic chemical resistance, hardness, scratch resistance, and adhesion to various substrates is formed, and have completed the present invention.

[0006]

SUMMARY OF THE INVENTION That is, the present invention provides (1) colloidal silica and general formula

Embedded image (In the formula, x is 0 or 1, and R is an alkyl group, a vinyl group, a phenyl group, an aminoalkyl group, a methacryloxyalkyl group, a glycidoxyalkyl group, a polyoxyalkylene group or a polyoxyalkylenealkyl group. Yes,
R ¹ is an alkyl group or a phenyl group, and R ² is a lower alkyl group.) A product obtained by reacting an organic silicon compound represented by A coating composition comprising a main component; (2) a method of coating an inorganic substrate or an organic substrate with the coating composition according to (1) above; and (3) above (2). It is a substrate coated by the method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The colloidal silica used in the present invention is a colloid of silicon dioxide or a hydrate thereof obtained by dialysis of a silicate with dilute hydrochloric acid. A typical example is 20 to 40 anhydrous silicic acid.
%, And the content of soda as sodium oxide is 0.3
~ 0.4% or less, pH 9.5 to 10.5, 25 ° C
The viscosity is 30 cp or less, the specific gravity at 20 ° C. is 1.10 to 1.40, the appearance is transparent milky white and contains 20 to 40% silicic acid, and the content of soda as sodium oxide is 0.05. %, PH 2 to 4, viscosity at 25 ° C. is 5 cp or less, specific gravity at 20 ° C. is 1.10 to 1.20, and appearance is transparent milky white.

[0008] to the surface of the particle -SiOH group and -OH ^-
Ions are present, an electric double layer is formed by the alkali ions, and is stabilized by repulsion between particles.

Colloidal silica is usually marketed as an aqueous dispersion, and for example, Adelite AT (manufactured by Asahi Denka Kogyo), Snowtex (manufactured by Nissan Kagaku), Ludox (manufactured by DuPont), Nalcoag (manufactured by National Aluminate), Examples include Cytolon (manufactured by Monsanto Chemical), but are not limited thereto.

The organic silicon compound used in the present invention has the general formula

Embedded image (In the formula, x is 0 or 1, and R is an alkyl group, a vinyl group, a phenyl group, an aminoalkyl group, a methacryloxyalkyl group, a glycidoxyalkyl group, a polyoxyalkylene group or a polyoxyalkylenealkyl group. Yes,
R ¹ is an alkyl group or a phenyl group, and R ² is a lower alkyl group such as a methyl group, an ethyl group or a propyl group. ). Specific compounds include ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, and methylethyldimethoxysilane. , Methylethyldipropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxy Propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β
-(Aminoethyl) -γ-aminopropyltriethoxysilane, phenyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylethyldiethoxysilane, γ-aminopropylethyl Dimethoxysilane,
γ-aminopropylphenyldiethoxysilane, 2-amino-1-methylethyltriethoxysilane, N-methyl-γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, N-butyl-γ -Aminopropylmethyldiethoxysilane, N
-Β- (aminoethyl) -N-β- (aminoethyl)-
γ-aminopropyltrimethoxysilane, methyltriisopropoxysilane, methyltriisobutoxysilane,
Examples thereof include, but are not limited to, ethyltriisopropoxysilane, ethyltriisobutoxysilane, dimethyldiisopropoxysilane, dimethyldiisobutoxysilane, methylethylisopropoxysilane, and methylethylisobutoxysilane. Moreover, Si
Tetraalkoxy such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetraisopropoxysilane, and tetraisobutoxysilane represented by (OR ¹ ) ₄ (wherein R ¹ has the same meaning as described above). Silane, ethyl orthosilicate and their 3 to 1
A mer or the like, which is a 0-mer, may be used at the same time.

The reaction solvent used in the reaction between the colloidal silica and the organosilicon compound is water, ethanol,
Examples include methanol, isopropyl alcohol, ethylene glycol monobutyl ether, acetone, ethylene glycol, propylene glycol, ethyl glycols, butyl glycols, etc., but it is preferable to use water from the viewpoint of environmental problems, economics, and safety. .

The use ratio of colloidal silica and organosilicon compound is not particularly limited, but the ratio of the amount of silicic acid anhydride in the colloidal silica to the organosilicon compound is 1: 100 to.
It is preferably in the range of 1: 0.2. When the amount of the organic silicon compound used is larger than this range, the stability of the coating composition is deteriorated, which is not preferable. On the other hand, if the amount of the organic silicon compound used is less than this range, the strength of the coating film and the adhesion to the substrate will be weakened, and the transparency of the coating film will be lost, which is not desirable.

The reaction between the colloidal silica and the organic silicon compound is completed within 1 to 36 hours in the above-mentioned reaction solvent at a temperature of 0 to 80 ° C. In the reaction product, a reaction solvent and alcohols such as methanol, ethanol and butanol as by-products are mixed. If necessary, remove all or part of these reaction solvents and alcohols,
Alternatively, water or another solvent may be added. In particular, it is preferable to remove solvents and alcohols other than water, because special equipment may be required at the site where the coating composition is applied to the substrate due to toxicity and flammability.

The reaction product of colloidal silica and an organic silicon compound described in detail above was invented as a scratch-shielding agent for glass containers such as beer, soft drinks, milk, etc.
No. 8745. The above-mentioned product has an excellent effect of eliminating scratches on a scratched glass container, but lacks resistance to acids and alkalis, heat resistance, etc., and further has poor adhesion to organic substrates such as resins. Therefore, it is not suitable to be used alone as the coating composition of the present invention.

The room temperature curable silicone acrylic resin emulsion used in the present invention has the following formula:

Embedded image (In the formula, y is 0 or 1, 2, R ³ is a hydrogen atom or an alkyl group or an aralkyl group, R ⁴ is a halogen atom, or a hydroxyl group, an alkoxy group, an acyloxy group, a phenoxy group, an iminooxy group or an alkenyloxy group. In addition to the essential requirement that the emulsion is an acrylic resin having a hydrolyzable group or a hydrolyzable group represented by (1), the bonding position of the hydrolyzable group and the hydrolyzable group bonded to the acrylic main chain The organic group, molecular structure, degree of polymerization, emulsification method and the like are not particularly limited, and various conventionally known ones can be used. For example, Japanese Patent Laid-Open No. 5-
25354, JP-A-4-261454, and JP-A-6-57.
198, JP-A-6-025502, etc., glass coat SW-135, glass coat E.
W-01, glass coat EW-430 (above Sanyo Kasei Kogyo Co., Ltd.), Cymac USE (Toagosei Kagaku Kogyo Co., Ltd.) and the like that are commercially available can be used.

The coating composition of the present invention contains a reaction product of colloidal silica and an organic silicon compound and a silicone acrylic resin emulsion as main components. The reaction product and the silicone-acrylic resin emulsion may be mixed by an ordinary method such as stirring and shaking. The reaction product and the silicone-acrylic resin emulsion may be mixed in advance, or may be mixed just before use.

The mixing ratio of the reaction product and the room temperature curable silicone acrylic resin emulsion is not particularly limited, but the silicone acrylic resin emulsion is 1 to 10 parts by weight based on 100 parts by weight of the solid content of the reaction product.
It is preferable to use 000 parts by weight, particularly 10 to 1000 parts by weight. When the compounding ratio of the silicone acrylic resin emulsion is smaller than the above range, the adhesiveness to the organic substrate, water resistance, weather resistance and the like are not preferable, and on the other hand, when the compounding ratio is larger than the above range, heat resistance The coating film hardness is not sufficient, which is not preferable.

The coating composition of the present invention may be diluted with water or the like, if necessary, or the water or solvent may be removed under reduced pressure to remove the amount of active ingredient (a reaction product of colloidal silica and an organosilicon compound). It can be used by adjusting the solid content and the total solid content of the silicone acrylic resin emulsion.
The amount of the active ingredient is not particularly limited, but if it is 50% by weight or more, it becomes difficult to form a uniform coating film, which is not preferable. On the other hand, if it is less than 1% by weight, only a very thin coating film is formed, and the functionality of the coating film such as scratch resistance, organic chemical resistance, and weather resistance cannot be fully exhibited, which is not preferable.

The coating composition of the present invention may undergo a hydrolysis reaction in an aqueous solution, which may significantly reduce its stability and performance. Therefore, p
It is advisable to adjust H to 8 or less, preferably 5 to 7, to stabilize the coating composition. The buffer is the pH of the composition
Is used to buffer within a specific range, and widely known ones are appropriately used in the present invention.
Representative examples of useful buffering agents include organic acids, inorganic acids, bases and salts thereof, preferably acetic acid, lactic acid, carbonic acid, phosphoric acid, sulfuric acid, carboxylic acid, alkaline earth metal salts, ammonium salts, ammonia and the like. Is a mixture of.
Specific compounds include acetic acid, sodium acetate, ammonium acetate, lactic acid, sodium lactate, hydrochloric acid, sodium borate and the like. The amount of the buffering agent used can be set within a wide range in order to achieve the above purpose, but it is generally preferably 0.01 to 5% by weight in the entire composition.

When a polydiorganosiloxane emulsion is added to the coating composition of the present invention,
It has the effect of imparting smoothness to the coating film and improving the leveling property. These emulsions can be prepared, for example, by adding polyoxyethylene nonylphenyl ether and water to dimethylpolysiloxane having a viscosity at 25 ° C. of 10,000 cp or less and emulsifying with a homomixer.

Further, the coating composition of the present invention,
A water-soluble resin such as a water-soluble melamine resin or a water-soluble acrylic resin may be added. By adding these, a hard and uniform coating film can be easily formed.

The coating composition of the present invention contains the commonly used pigments, dyes, antistatic agents, crosslinking agents, antifogging agents,
Lubricants, metal powders, antioxidants, UV inhibitors, antibacterial agents,
An antifungal agent or the like can be added in an appropriate amount if necessary.

The coating composition of the present invention can be formed into a coating film by curing by evaporation of water if it is left in the air after coating by a known method usually applied to a substrate. Examples of the application method include a method of manually applying with a woven cloth, a non-woven cloth, a foam, a felt, a brush, etc., a method of fixing these to a belt and mechanically applying them, a dipping method, a spraying method and the like.

[0024]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these, and all embodiments utilizing the technical idea of the present invention are included in the scope of the present invention. Is.

I. Preparation of Coating Composition Water was added to Glass Coat SW-135 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) to adjust the solid content to 35% by weight to prepare Silicon Acrylic Resin Emulsion 1. Further, water was added to Cymac USE (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) to adjust the solid content to 35% by weight to obtain a silicone acrylic resin emulsion 2.

After colloidal silica, an organic silicon compound, distilled water and a solvent were mixed in the composition shown in Table 1 and stirred, the mixture was placed in a glass reactor equipped with a reflux condenser, a thermometer, a dropping funnel, etc. The mixture was refluxed for 4 hours to carry out the reaction. Then, after removing the solvent and the generated alcohol under reduced pressure,
Water was added to adjust the solid content to 35%.

[Table 1] * 1 to * 11 in Table 1 represent the following. * 1 Nissan Chemical Co., Ltd. Silica anhydride content 20-21% by weight Hydrogen ion concentration 2-4 Particle size 10-20mμ * 2 Nippon Unicar A-162 * 3 Nippon Unicar A-153 * 4 Nippon Unicar prototype * 5 Nippon Unicar A-151 * 6 Nippon Unicar A-1100 * 7 Nippon Unicar A-174 * 8 Nippon Unicar A-187 * 9 Nippon Unicar prototype * 10 Nippon Unicar prototype * 11 Japan Unicar Prototype After that, silicone acrylic resin emulsion 1 and silicone acrylic resin emulsion 2 were added to these reaction products according to the formulation shown in Table 2, and the mixture was stirred to give Examples 1 to 14.
And the coating composition of Comparative Examples 1-4 was prepared.

II. Coating film evaluation test The coating compositions of Examples 1 to 14 and Comparative Examples 1 to 4 prepared by the above method were used as stainless steel plates (SUS 304).
It is applied on the surface so that the film thickness when dried is 6 μm, and after curing under various test conditions, it has curability, acid resistance, water resistance, organic chemical resistance, adhesion to various substrates and scratch resistance. The test was carried out by the method shown below, and the test results are shown in Table 2. Further, the same test is performed on various base materials, and an aluminum plate (JIS H
400A1050P) in Table 3, the glass plate (JIS R3202 float plate) in Table 4, and the polycarbonate plate (JIS K6747-8).
The results for 1) are shown in Table 5, respectively.

[Table 2]

[Table 3]

[Table 4]

[Table 5] As shown in Tables 2 to 5, Examples 1 to 14, which are coating compositions of the present invention, have curability and acid resistance with respect to various base materials as compared with the coating compositions of Comparative Examples 1 to 4. ,
It can be seen that a coating film having excellent water resistance, organic chemical resistance, adhesion to various base materials and scratch resistance can be formed.

Curing test After coating, the mixture was allowed to stand for 12 hours at room temperature, and then judged by the following criteria with a tentacle. 1: Completely cured (tack free). 2: Slightly hardened but usable. 3: Insufficient curing.

Water resistance test After coating, after allowing to stand for 24 hours at room temperature, after soaking in ion-exchanged water at 70 ° C. for 72 hours, the state of the coating film was visually observed and judged according to the following criteria. ◯: No change. Δ: The coating film was slightly devitrified. X: Almost the entire surface of the coating film was whitened.

Acid resistance test After coating, after allowing to stand at room temperature for 24 hours, 1
A 0% aqueous solution of sulfuric acid was spotted, heated at 50 ° C. for 1 hour and washed with water, and then the state of the coating film was observed with the naked eye and judged according to the following criteria. ◯: No change. Δ: A mark remained on the spotted portion. X: The spotted portion of the coating film was peeled off.

Organic chemical resistance test After coating, after allowing to stand for 24 hours at room temperature, toluene was spotted on the coating film, and after standing for 72 hours at room temperature, the state of puffing and peeling was observed. It was judged. ◯: Plow and peeling were hardly seen, and the state of the coating film was good. X: Peeling and peeling occurred and the coating film became rough.

Adhesion Test with Various Substrates After coating, after allowing to stand for 24 hours at room temperature, soaking in ion-exchanged water at 70 ° C. for 72 hours, observing the state of the coating film with the naked eye, the cross-cutting method (1 mm Corner, 100 pieces of cellophane tape peeled)
It was judged according to the following criteria by the number of peeled. ○: 0 △: 0-10 ×: 10-100

Heat resistance test After coating, the mixture was allowed to stand at room temperature for 24 hours, then allowed to stand in an oven at 200 ° C. for 100 hours, and the state of the coating film was visually observed and judged according to the following criteria. ◯: No change. Δ: The coating film was slightly whitened or yellowed. X: Whitening and yellowing occurred on almost the entire coating film surface.

Scratch resistance test Steel wool # 000 after 24 hours at room temperature
Rubbing and observing the state of the coating film with the naked eye were judged according to the following criteria. ◯: No change. X: Remarkably scratched.

III. Stability Test of Coating Compositions The coating compositions of the present invention of Examples 1 to 6 were prepared, placed in glass bottles, sealed, and allowed to stand in a room at 25 ° C. The appearance after 6 months did not change from the time of preparation. In addition, the above-mentioned various tests were conducted, but no difference in performance of the coating film was observed immediately after preparation.

[0036]

EFFECT OF THE INVENTION The coating composition of the present invention has excellent stability and is less risk of toxicity and flammability because it is an aqueous system, and metal, as well as inorganic base materials such as cement, mortar, concrete and glass, Plastic, wood, paper,
It is possible to form a coating film having high adhesion at room temperature on the surface of an organic substrate such as fiber. The coating film is excellent in water resistance, heat resistance, weather resistance, acid resistance, organic chemical resistance, hardness, scratch resistance and the like. Since it has excellent properties like these, the coating composition of the present invention is a coating agent for surface protection of a substrate such as a hard coating agent for plastics, a strength reinforcing agent, various paints (weather resistant paint, acid resistant paint, It is very useful as a hard coat paint, water repellent paint, heat resistant paint, etc.). Also,
Since various substrates coated with the coating composition of the present invention are coated with the excellent coating film as described above,
It is very useful in a wide range of industrial fields such as building materials, automobiles, electric and electronic parts.

Claims (3)

[Claims] 1. Colloidal silica and a general formula: (In the formula, x is 0 or 1, and R is an alkyl group, a vinyl group, a phenyl group, an aminoalkyl group, a methacryloxyalkyl group, a glycidoxyalkyl group, a polyoxyalkylene group or a polyoxyalkylenealkyl group. Yes,
R ¹ is an alkyl group or a phenyl group, and R ² is a lower alkyl group.) A product obtained by reacting an organic silicon compound represented by the formula (1) in a solvent, and a room temperature curable silicone acrylic resin emulsion. A coating composition comprising: 2. A method for coating an inorganic substrate or an organic substrate with the coating composition according to claim 1. 3. A substrate coated by the method of claim 2.