JP2001098073A - Method for producing aqueous organopolysiloxane solution and coating composition - Google Patents

Abstract

(57) [Abstract] (Modified) [Problem] It has excellent storage stability, and has curability, water resistance,
Provided is an aqueous organopolysiloxane solution used for a coating composition for forming a coating film having excellent stain resistance and the like. SOLUTION: (I) (a) Formula (1) (R ¹ ) _n Si (O)
R ² ) _4-n [n is 1 or 2. 100 parts by weight of the organosilane and / or its partially hydrolyzed condensate, and (b) the amino group-containing alkoxysilane 3 to 10
0 parts by weight, (c) Formula (2) [N is 0, 1 or 2. To 470 parts by weight of the silyl group-containing organic compound represented by the formula (1), and (d) 1 equivalent of the total hydrolyzable functional groups in the components (a), (b) and (c). A mixture comprising -0.5 equivalents of water, a hydrolysis condensation reaction,
(II) Step of adding an acid in an amount to neutralize 0.25 to 0.65 equivalents of amino groups and water, and further subjecting to hydrolysis and condensation reaction; (III) Reaction product obtained in step (II) Adding a neutralizing agent to the solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aqueous organopolysiloxane solution having excellent storage stability, and a curable, frost-resistant and water-resistant resin containing the aqueous organopolysiloxane as a binder. The present invention relates to a coating composition that forms a coating film having excellent stain resistance, adhesion, pigment dispersibility, and the like.

[0002]

2. Description of the Related Art In recent years, environmental regulations regarding reduction of volatile organic compounds (VOCs) and toxicity have become stricter. In addition, from the viewpoint of resource saving, the coating industry has used water as a solvent from coatings using organic solvents. Conversion to used paints is being made. Water-based paints using water as a solvent, those using synthetic resins as binders have been widely put to practical use, but inorganic paints using organopolysiloxane as binders are apt to gel during storage, At present, it has not been put to practical use due to poor storage stability and poor curability.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is directed to a method for producing an aqueous organopolysiloxane solution having excellent storage stability, and the aqueous organopolysiloxane solution. It is an object of the present invention to provide a coating composition which forms a coating film having excellent curability, frost damage resistance, water resistance, stain resistance, adhesion, and pigment dispersibility, using as a binder.

[0004]

Means for Solving the Problems The present inventor has conducted intensive studies to achieve the above object, and as a result, has the following structure.
The inventors have found that the above-mentioned object can be surely achieved, and have reached the present invention. That is, the present invention relates to the following inventions. 1. (I) (a) Formula (1) (R ¹ ) _n Si (OR ² )
_4-n wherein, R ¹ is an organic group having 1 to 8 carbon atoms, R ²
Is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2
It is. 100 parts by weight of the organosilane and / or its partially hydrolyzed condensate, (b) 3 to 100 parts by weight of an amino group-containing alkoxysilane, and (c) the formula (2)

[0005]

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Wherein R ¹ and R ² have the same meaning as described above, A is (CH ₂ ) _m , m is an integer of 1 to 8, and n is 0, 1 or 2. To 470 parts by weight of the silyl group-containing organic compound represented by the formula (1), and (d) 1 equivalent of the total hydrolyzable functional groups in the components (a), (b) and (c). To 0.5 equivalents of water, and then subjecting the mixture to a hydrolysis and condensation reaction, and then (II) 0% of amino groups in the hydrolysis and condensation product of the partial hydrolysis and condensation product solution obtained in the step (I). .25-
A step of adding 0.65 equivalents of an acid to neutralize the acid and at least 0.8 equivalents or more of water based on 1 equivalent of the total hydrolyzable functional groups, and further subjecting to a hydrolytic condensation reaction;
I) a method for producing an aqueous organopolysiloxane solution having a pH of 5.5 or less, which comprises a step of adding a neutralizing agent to the reaction solution obtained in step (II). 2. A coating composition containing the aqueous organopolysiloxane obtained in the above item 1 as a binder.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Each component used for producing the aqueous organopolysiloxane solution of the present invention will be described.

Component (a) The component (a) is represented by the formula (1) (R ¹ ) _n Si (OR ² ) wherein R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. And / or a partially hydrolyzed condensate thereof. In the above formula, examples of the organic group as R ¹ include an alkyl group, a cycloalkyl group, an aryl group, and an alkyl group.

Here, the alkyl group may be linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a pentyl group, and a hexyl group. And an alkyl group such as a heptyl group and an octyl group. Preferred alkyl groups have, for example, 1 to 4 carbon atoms.

The alkenyl group may be linear or branched. As the alkenyl group, specifically, for example,
Vinyl group, allyl group, n-butenyl group, isobutenyl group, sec-butenyl group, t-butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, etc., having 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms. The alkenyl group of the above is preferably mentioned.

Preferred examples of the cycloalkyl group include a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and a cyclononyl group. Further, as the aryl group, for example, a phenyl group, a naphthyl group and the like are preferably mentioned. Each of the above functions may optionally have a substituent. As such a substituent, for example, a halogen atom (for example, a chlorine atom, a bromine atom, a fluorine atom and the like), a (meth) acryloyl group, a mercapto group, an amino group, an alicyclic group and the like are preferably exemplified. .

The alkyl group as R ² may be linear or branched. As the alkyl group, specifically,
For example, alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, and pentyl are preferred. Preferred alkyl groups have, for example, 1 to 2 carbon atoms.

Specific examples of the organosilane represented by the above formula (1) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyl Triethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane,
γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxy Silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane,

Γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane And diphenyldiethoxysilane, methylphenyldimethoxysilane, dimethyldipropoxysilane and the like, and preferably, methyltrimethoxysilane, methyltriethoxysilane and dimethyldimethoxysilane.

These organosilanes can be used alone or in combination of two or more.
The component (a) may be a partially hydrolyzed condensate of the organosilane described above. The polystyrene-equivalent weight average molecular weight of the condensate is, for example, 300 to 5,000, preferably 500 to 3,000, and by using a condensate having such a molecular weight, storage stability is not impaired. A coating film having good adhesion is obtained. Also,
Partially hydrolyzed condensate of the organosilane, and -OH group bonded to a silicon atom, the -OR ² group 1 or more, and preferably those having 3 to 30.

As a specific example of such a condensate, for example, as a commercial product, SH6 manufactured by Dow Corning Toray Co., Ltd.
018, SR2402, DC3037, DC307
4: KR-211 or KR-21 manufactured by Shin-Etsu Chemical Co., Ltd.
2, KR-213, KR-214, KR-216, KR
-218; TSR-145 manufactured by Toshiba Silicone Co., Ltd.
SR-160, TSR-165, YR-3187 and the like.

In the present invention, in combination with the component (a), for the purpose of improving the storage stability of the coating composition and improving the crack resistance and the like of the obtained coating film,
Formula (R ¹ ) ₃ Si (OR ² ) wherein R ¹ and R ² are
It has the same meaning as the formula (1) of the component (a). With respect to 100 parts by weight of the component (a).
It is also possible to mix in a range not exceeding 20 parts by weight. Specific examples of such an organosilane include, for example, methoxytrimethylsilane, ethoxytrimethylsilane, ethoxydiphenylmethylsilane, and the like.

Component (b) The component (b) is an alkoxysilane having an amino group in the molecule and capable of undergoing a hydrolysis-condensation reaction. Preferably, an alkoxysilane represented by the following formula (3) is suitably used. can do.

(R ⁵ —NH—R ⁴ —) _n Si (OR ³ ) _4-n

[Wherein, R ³ is an alkyl group having 1 to 5 carbon atoms, R ⁴ is an alkylene group having 1 to 5 carbon atoms, and R ⁵ is a hydrogen atom and 1 to 5 carbon atoms. An alkyl group, a cycloalkyl group having 5 to 8 carbon atoms, an aryl group having 6 to 8 carbon atoms, or a substituted or unsubstituted amino group;
Is an integer of 1 to 3. The alkyl group as R ³ may be linear or branched. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group,
Preferable examples include an alkyl group such as a pentyl group. Preferred alkyl groups have, for example, 1 to 2 carbon atoms.

R^FourAs the alkylene group
However, it may be branched. With such an alkylene group
For example, methylene group, ethylene group, propylene
And the like. R^FiveHaving 1 to 5 carbon atoms
The kill group is represented by R^ThreeIs the same as Also, R^Fiveage
Examples of all cycloalkyl groups include, for example, cyclohexyl
And a cycloheptyl group. Also, R^Five
Examples of the aryl group include a phenyl group and na
Examples include heterocyclic groups such as a futyl group and an anilino group. Change
And R ^FiveAs an amino group, one of the amino groups
The hydrogen atom or both hydrogen atoms are, for example, those having 1 carbon atom
5 to an alkyl group, further substituted with an amino group, etc.
Substituted with an alkyl group (eg, aminoethyl group, etc.)
Are preferred.

Examples of the amino group-containing alkoxysilane represented by the above formula include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyl Trimethoxysilane, N- (β-aminoethyl) -γ
-Aminopropylmethyldimethoxysilane, N- (β
-Aminoethyl) -γ-aminopropylmethyldiethoxysilane, N-cyclohexyl-γ-aminopropyltrimethoxysilane, N-cyclohexyl-γ-aminopropyltriethoxysilane, γ- (2-aminoethyl)
-Aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane,
γ-anilinopropyltrimethoxysilane and the like.

The component (b) is used in an amount of 3 to 100 parts by weight, preferably 5 to 50 parts by weight, per 100 parts by weight of the component (a). If the used amount is less than the above range, the obtained organopolysiloxane does not stably dissolve or disperse in water, so that storage stability is deteriorated.On the other hand, if the amount is too large, the water resistance of the obtained coating film is deteriorated. Not preferred. Component (c) Component (c) is represented by the general formula (2)

[0024]

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[0025] wherein, R ¹ and R ² are the same meaning as R ¹ and R ² of component (a) of the formula (1), A, (C
H ₂ ) _m , where m is an integer from 1 to 8, n is 0,
1 or 2. And a silyl group-containing organic compound represented by the formula: As specific examples of these silyl group-containing compounds,
1,3,5-N-tris (2-trimethoxysilylethyl) isocyanurate, 1,3,5-N-tris (3-
Triethoxysilylpropyl) isocyanurate, 1,
3,5-N-tris (3-trimethoxysilylpropyl) isocyanurate, 1,3,5-N-tris (3-
Methyl-3-dimethoxysilylpropyl) isocyanurate, 1,3,5-N-tris (3-dimethyl-3-methoxysilylpropyl) isocyanurate and the like. These silyl group-containing organic compounds may be used alone. , Or a mixture of two or more. As a commercially available product of such a silyl group-containing organic compound, Y-11597 manufactured by Nippon Yunika Co., Ltd. and the like can be mentioned.

The component (c) is suitably used in an amount of 1 to 470, preferably 20 to 200 parts by weight, based on 100 parts by weight of the component (a). However, when the content is too large, the weather resistance and the like are deteriorated. Next, a method for producing the aqueous organopolysiloxane solution of the present invention will be described. First, in the step (I), the components (a), (b) and (c) are subjected to hydrolysis and condensation in the presence of water.

The amount of water is 0.2 to 0.5 equivalent, preferably 1 equivalent of the total hydrolyzable functional group in the mixture of the component (a), the component (b) and the component (c). , 0.25
An amount that results in と 0.4 equivalents is appropriate. When the amount of water is less than the above range, the water dispersibility becomes worse, and when the amount is too large,
It is not preferable because polymerization stability such as gelation is deteriorated. The hydrolysis and condensation reaction is usually performed at 40 to 80 ° C., preferably,
A method in which the reaction is performed at 45 to 65 ° C., for example, for 2 to 5 hours is preferable, but the method is not limited to this method.
In the step (I), a hydrolysis-condensation product having a weight average molecular weight in terms of polystyrene of about 2500 to 20,000 is obtained. In addition, in this reaction system, it becomes a solution state by the alcohol generated by hydrolysis.

In the step (I), since the reaction is carried out in the absence of an acid as described later, unreacted organosilane tends to remain, which deteriorates the storage stability and curability. Further, in the next step (II), a hydrolysis condensation reaction is performed in the presence of an acid and water. In addition,
It is not preferable to carry out the reaction in the presence of an acid in the step (I) because the curability of the coating film deteriorates. In the step (II), 0.25 to 0.65 equivalents, preferably 0.35 to 0.60 equivalents of amino groups in the hydrolyzed condensate of the partially hydrolyzed condensate obtained in the step (I) The amount of acid to neutralize the equivalent and the equivalent of one equivalent of the total hydrolyzable functional groups are at least 0.1 equivalent.
8 equivalents or more, preferably 1.0 equivalents or more of water is added to carry out hydrolysis and condensation reaction.

The acid is compounded to have a reaction catalyst function and to react in a state of being stably dispersed or dissolved in a solution. Examples of the acid include inorganic acids such as nitric acid and hydrochloric acid, and organic acids such as acetic acid, formic acid, and propionic acid. When the amount of the acid is less than the above range, unreacted organosilane is apt to remain unchanged, and storage stability and curability are deteriorated.On the contrary, when the amount is too large, polymerization stability such as gelation is deteriorated. Is not preferred. On the other hand, when the amount of water is smaller than the above range, the hydrolytic condensation reaction of unreacted organosilane becomes insufficient. The upper limit of the amount of water is such that the solid content of the finally obtained aqueous organopolysiloxane solution is 15 to 60% by weight, preferably 20 to 40% by weight.

The hydrolysis-condensation reaction is, for example, 40-80.
C., preferably at 45-65.degree. C., usually for 2-5 hours, but the method is not limited to this method. In the step (II), a hydrolysis-condensation product having a weight average molecular weight in terms of polystyrene of about 5,000 to 50,000 is obtained, and the unreacted residual organosilane is eliminated. (II
In the step (I), a neutralizing agent and, if necessary, water for dilution are added so that the reaction solution obtained in the step (II) can be used stably as a coating agent.

As the neutralizing agent, the above-mentioned acids can be used, and the amount thereof is adjusted so that the pH of the solution is 5.5 or less, preferably 2.5
A value of about 4.5 is preferable because storage stability is good.
When the amount of water to be added in the step (II) is less than 15 to 60% by weight, preferably 20 to 40% by weight, of the finally obtained solution, Replenish the amount of In the aqueous organopolysiloxane solution thus obtained, an alcohol component is produced by the above-mentioned hydrolysis-condensation reaction, and this remains in the solution. Therefore, the alcohol content may be removed under reduced pressure if necessary.

Next, the coating composition of the present invention will be described. The coating composition of the present invention contains the above-mentioned aqueous organopolysiloxane as a binder, and further, if necessary, reduces the solid content of the composition to preferably 1%.
Water, organic solvents and fillers and dyes for adjusting the coating composition to about 0 to 50% by weight and improving the storage stability and coating workability of the coating composition, as well as a curing agent, a curing accelerator, It is composed of a mixture of various additives such as a thickener and a pigment dispersant. As the organic solvent, for example,
Methanol, alcohols such as ethanol, propanol and butanol, alcohol ethers such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, hydrophilic organic solvents such as ketones such as acetone and methyl ethyl ketone, and toluene, xylene, ethyl acetate and acetic acid An organic solvent mixed with various hydrophobic organic solvents for coatings such as butyl can be used.

As fillers, extenders and coloring pigments for various coatings such as talc, barium carbonate, calcium carbonate, bentonite, titanium oxide, carbon black, red iron, lithopone, etc. can be used. It is desirable that the curing agent and the curing accelerator are blended in order to accelerate the curability.
As the curing agent, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl)
Epoxy compounds such as ethyltrimethoxysilane and γ-glycidoxypropylmethyldiethoxysilane are typical examples. These curing agents have an equivalent ratio of the epoxy group to the amino group of the organopolysiloxane of (1: 0.3 to 1.5), preferably (1: 0.
5 to 1.0).

As the curing accelerator, for example, tin octylate, organotin compounds such as dibutyltin dilaurate, dibutyltin dimaleate and tributyltin laurate, and amine compounds such as ethylenediamine, diethylenetriamine, piperidine, phenylenediamine and triethylamine are typical. It is mentioned as a typical thing. These curing accelerators are desirably added in order to cure the coating composition faster at a relatively low temperature, and the amount thereof is, for example, 0.01 to 100 parts by weight of the binder.
~ 15 parts by weight is suitable.

The coating composition of the present invention is applied to the surface of the object to be coated by a coating means such as brush, spray, roll, dipping or the like, and is baked at room temperature or at a temperature of 300 ° C. or less to form a cured coating film. It is possible. In addition, as an object to be coated, an inorganic ceramic substrate, various metal substrates such as stainless steel and aluminum, a glass substrate, a plastic substrate, and a paper substrate can be applied to various objects to be coated.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, "parts" and "%" are shown on a weight basis unless otherwise specified. Example 1 In a reactor equipped with a reflux condenser and a stirrer, (a) a partially hydrolyzed cocondensate of phenyltrimethoxysilane and dimethyldimethoxysilane (DC3074 manufactured by Dow Corning Toray Co., Ltd .; solid content: 100%) ) 43 parts, 11 parts of methyltriethoxysilane, 46 parts of dimethyldiethoxysilane, (b) 12 parts of N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, (c) 1,
After adding and mixing 30 parts of 3,5-N-tris (3-trimethoxysilylpropyl) isocyanurate, 6.7 parts of ion-exchanged water was added with stirring (0.5 parts per equivalent of total hydrolyzable functional groups). 3 equivalents) at 60 ° C.
The hydrolysis and condensation reaction was performed for a time.

With respect to 100 parts by weight of the obtained solution, 13.4 parts of ion-exchanged water (corresponding to 1 equivalent per 1 equivalent of the total hydrolyzable functional groups) and 8.7 parts of 5N hydrochloric acid (hydrolysis) (0.6 equivalent of an amino group in the condensate), and the mixture was reacted at 60 ° C. for 3 hours under the condition of pH 8.0. Then, after cooling, 155 parts of ion-exchanged water and 5N-
Hydrochloric acid was added to adjust the pH of the solution to 4.3, whereby an aqueous organosiloxane solution A having a solid content of 28% was prepared.

Example 2 In a reactor equipped with a reflux condenser and a stirrer, (a)
50 parts of DC3074 and 50 parts of dimethyldiethoxysilane manufactured by Dow Corning Co., Ltd., (b) 10 parts of N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, and (c) 1,3,5 After adding and mixing 20 parts of -N-tris (3-trimethoxysilylpropyl) isocyanurate, 7.5 parts of ion-exchanged water (0.3 equivalent to 1 equivalent of the total hydrolyzable functional group) is added with stirring. Was added, and reacted at 60 ° C. for 3 hours.

With respect to 100 parts of the obtained solution, 14.5 parts of ion-exchanged water (corresponding to 1 equivalent per 1 equivalent of the total hydrolyzable functional groups) and 8.0 parts of 5N hydrochloric acid (hydrocondensation) 0.6 equivalents of amino groups in the product)
The reaction was carried out at 60 ° C. for 3 hours under the condition of H8.0. Then, after cooling, 140 parts of ion-exchanged water and 5N-hydrochloric acid were added to p.
H was added to 4.3 to prepare an aqueous organosiloxane solution B having a solid content of 28%.

Example 3 In a reactor equipped with a reflux condenser and a stirrer, (a)
60 parts of DC3074 manufactured by Dow Corning KK, 15 parts of methyltriethoxysilane and 25 parts of dimethyldiethoxysilane, and (b) N- (β-aminoethyl) -γ-
15 parts of aminopropylmethyldiethoxysilane,
(C) 100 parts of 1,3,5-N-tris (3-trimethoxysilylpropyl) isocyanurate was added and mixed, and then, with stirring, 12 parts of ion-exchanged water (to 1 equivalent of the total hydrolyzable functional group). (Equivalent to 0.31 equivalent), and reacted at 60 ° C. for 3 hours under the condition of pH 9.5.

For 100 parts of the obtained solution, 13 parts of ion-exchanged water (corresponding to 1 equivalent per 1 equivalent of the total hydrolyzable functional groups) and 2 parts of acetic acid (amino group 0 0.52 equivalents), and reacted at 60 ° C. for 3 hours under the condition of pH 8.0. Then, after cooling,
170 parts of ion-exchanged water and acetic acid were adjusted to pH 4.0.
And an aqueous organosiloxane solution C having a solid content of 30% was prepared.

Comparative Example 1 To a reactor equipped with a reflux condenser and a stirrer, (a)
43 parts of DC3074 manufactured by Dow Corning, 11 parts of methyltriethoxysilane and 46 parts of dimethyldiethoxysilane, and (b) N- (β-aminoethyl) -γ-
12 parts of aminopropyltrimethoxysilane and (c)
After adding and mixing with 1,3,5-N-tris (3-trimethoxysilylpropyl) isocyanurate 30, 6.7 parts of ion-exchanged water (with respect to 1 equivalent of the total hydrolyzable functional group) is stirred while stirring. 0.3 equivalent) at 60 ° C.
The hydrolysis and condensation reaction was performed for a time.

With respect to 100 parts by weight of the obtained solution, 13.4 parts of ion-exchanged water (corresponding to 1 equivalent relative to 1 equivalent of the total hydrolyzable functional groups) was added and reacted at 60 ° C. for 3 hours. Next, after cooling, 155 parts of ion-exchanged water and 5N-hydrochloric acid were added so that the pH of the solution was 4.3, and the solid content was 2%.
An 8% aqueous organosiloxane solution D was prepared. Was.

Comparative Example 2 To a reactor equipped with a reflux condenser and a stirrer, (a) Toray
50 parts of DC3074 and 50 parts of dimethyldiethoxysilane manufactured by Dow Corning Co., Ltd., and 10 parts of (b) N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane were added and mixed, followed by stirring. 6.0 parts of ion-exchanged water (0.3 equivalent to 1 equivalent of total hydrolyzable functional groups)
(Equivalent to an equivalent weight), and a hydrolysis condensation reaction was performed at 60 ° C. for 3 hours. For 100 parts by weight of the obtained solution, 10.0 parts of ion-exchanged water (corresponding to 1 equivalent per 1 equivalent of the total hydrolyzable functional groups) and 8.0 parts of 5N hydrochloric acid (in the hydrolyzed condensate) And 0.6 equivalent of an amino group of the above), and reacted at 60 ° C. for 3 hours under a condition of pH 8.0.

Next, after cooling, 150 parts of ion-exchanged water and 5N-hydrochloric acid were added so that the pH of the solution became 4.3, whereby an aqueous organosiloxane solution E having a solid content of 25% was prepared. Was.

In order to examine the storage stability of each aqueous organosiloxane solution obtained in Examples 1 to 3 and Comparative Examples 1 and 2, each solution was allowed to stand at 50 ° C. Was measured for the change in viscosity as compared with the initial stage, and the results are shown in Table 1 below. Evaluation criteria 〇: viscosity change less than 1.2 times △: viscosity change 1.2 to less than 2.0 ×: viscosity change 2.0 times or more

Further, 100 parts of the aqueous organosiloxane solution obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were added to 10 parts of γ-glycidoxypropyltrimethoxysilane (curing agent).
And 10 parts of a 10% aqueous dispersion of dibutyltin dilaurate (curing accelerator) were added to prepare a coating composition. For each coating composition, various tests were conducted for the appearance, hardness, hot water resistance, stain resistance, alkali resistance, solvent resistance, and frost resistance of the resulting coating film, and the results are shown in Table 1.
It was shown to.

The test was performed according to the following method. <Coating film performance test> A gypsum slag perlite plate (thickness: 12 mm) was used as a material, and a polyisocyanate prepolymer solution sealer “V-Selan # 100 Sealer” (trade name, manufactured by Dainippon Paint Co., Ltd.) (butyl acetate) was used on the surface. : 100% dilution with a 1: 1 solution of xylene).
The composition was spray-coated so as to be １００100 g / m ² (wet weight). This was dried at 100 ° C. for 5 minutes.

Next, as a base paint, an acrylic silicone resin-based paint "V-Seran # 500 Enamel" (trade name, manufactured by Dainippon Paint Co., Ltd.) (butyl acetate: xylene =
(A 40% dilution with a 1: 1 solution).
m ² (wet weight). This was dried at 120 ° C. for 15 minutes. Next, the coating amount of each of the above-mentioned coating compositions was (130 ± 10) g / m ² (w
(weight). 120 ° C
, And then dried at room temperature for 3 days.

Appearance: Judged visually. Hardness: Pencil hardness measured according to JIS K5400 Hot water resistance: A test piece was immersed in tap water at 60 ° C. for 7 days to visually determine the abnormality of the appearance of the coating film. Evaluation criteria ○ ・ ・ ・ No change △ ・ ・ ・ Minor change such as gloss reduction, whitening etc. × ・ ・ ・ Large change such as gloss reduction, whitening etc.

Stain resistance: Twenty-four hours after the application of Red and Black Magic Ink (registered trademark), the stain was wiped off with a cloth wetted with n-butanol, and decontamination was visually evaluated. Evaluation criteria ◎ ・ ・ ・ Complete removal ○ ・ ・ ・ Extremely slight contamination △ ・ ・ ・ Contamination × ・ ・ ・ Significant contamination

Alkali resistance: The state of the coating film after immersion in a saturated slaked lime aqueous solution for one week was visually judged. Evaluation criteria ◎ ・ ・ ・ No change ○ ・ ・ ・ Slight decrease in gloss △ ・ ・ ・ Decrease in gloss, slight whitening × ・ ・ ・ Decrease in gloss, significant whitening

Solvent resistance: Rubbing test using cloth wet with xylene and cloth wet with n-butanol Evaluation criteria: Both solvents passed 50 times rubbing test △: 50 times rubbing test with one solvent Whitening ×: Both solvents were whitened in the rubbing test 50 times.

Freezing damage resistance: Measured by the ASTM-C666A method Evaluation criteria ・ ・ ・: No cracking, no change in gloss: No cracking, but slight decrease in gloss ・ ・ ・: Slight cracking・ Significant crack generation

[0055]

[Table 1] Table 1Example Comparative example 1 2 3 1 2 Aqueous organopolysiloxane solution ABCDEType of Storage stability ○ ○ ○ × ○ Appearance good good good good Hardness 2H 2H 2H H 2H Hot water ○ ○ ○ △ ○ Stain resistance ◎ ◎ ◎ ○ ○ Alkali resistance ◎ ◎ ◎ △ ○ Solvent resistance ○ ○ ○ △ ○ Freezing damage resistance 80 cycles ◎ ◎ ◎ ○ ○ 160 cycles ○ ○ ○ △ ×

As is evident from Table 1, the coating compositions of Examples 1 to 3 used for the top coat paint were all excellent in storage stability and excellent in film performance. On the other hand, the coating composition of Comparative Example 1 obtained by carrying out the hydrolysis-condensation reaction in the absence of acid has poor storage stability, hot water resistance and solvent resistance of the obtained coating film, and (c) The coating composition of Comparative Example 2 obtained by performing a hydrolysis-condensation reaction in a state containing no component had poor frost damage resistance.

The aqueous organopolysiloxane solution produced by the method of the present invention is excellent in storage stability, and the coating composition using the aqueous organopolysiloxane as a binder has excellent curability, frost resistance and water resistance. To form a coating film having excellent stain resistance and the like.

Continued on the front page (72) Inventor Hiroharu Sasaki 7-1414-46 Shimonagata, Nishinasuno-machi, Nasu-gun, Tochigi F-term (reference) 4J035 BA14 CA061 CA19M CA19U CA22M CA22U FB01 LA07 LB01 4J038 DL081 GA09 MA08 MA12 NA05 NA06 NA12 NA23 NA26 PC02 PC03 PC04 PC08 PC10

Claims (2)

[Claims] (I) (a) Formula (1) (R ¹ ) _n Si (O
R ² ) _{4-n wherein} R ¹ is an organic group having 1 to 8 carbon atoms, R ² is an alkyl group having 1 to 5 carbon atoms, and n is
1 or 2. 100 parts by weight of the organosilane and / or its partial hydrolyzed condensate, (b) 3 to 100 parts by weight of an amino group-containing alkoxysilane, and (c)
Formula (2) Wherein R ¹ and R ² have the same meaning as described above, and A is
(CH ₂ ) _m , where m is an integer of 1 to 8, and n is
0, 1 or 2. 1 to 470 parts by weight of a silyl group-containing organic compound represented by the following formula (d):
A step of subjecting a mixture consisting of 0.2 to 0.5 equivalent of water to 1 equivalent of the total hydrolyzable functional groups in the component (b) and the component (c) to a hydrolysis-condensation reaction;
I) an acid in an amount to neutralize 0.25 to 0.65 equivalents of amino groups in the hydrolyzed condensate of the partially hydrolyzed condensate solution obtained in step (I); A step of adding at least 0.8 equivalent or more of water to 1 equivalent and further subjecting to a hydrolytic condensation reaction, and then (III) a step of adding a neutralizing agent to the reaction product solution obtained in the step (II), A method for producing an aqueous organopolysiloxane solution having a pH of 5.5 or less, characterized by comprising: 2. A coating composition comprising the aqueous organopolysiloxane obtained in claim 1 as a binder.