JP6368878B1 - Method for producing aqueous silicone resin emulsion for preparing coating composition - Google Patents

Abstract

A method for producing an aqueous silicone resin emulsion for preparing a coating composition.
From the following steps: an emulsification step of mechanically emulsifying a mixture of a silicone resin (A), an organic solvent (B), an emulsifier (C) and an aqueous medium, and the resulting emulsified mixture, (B) comprising a branched organopolysiloxane having a weight average molecular weight in the range of 5,000 to 300,000, and (B) (A) is an organic solvent which is mixed in an arbitrary ratio and has a solubility in water of 1 g / 100 gH ₂ O or less, or a mixture thereof, wherein at least one of the organic solvents has an azeotropic point with water And the mass ratio of (A) and (B) contained in the emulsified mixture satisfies the relationship of (A) :( B) = 1: 2 to 1: 0.2.
[Selection figure] None

Description

  The present invention relates to a method for producing an aqueous silicone resin emulsion for preparing a coating composition.

  Various exterior coating compositions are applied to the wall surfaces of buildings such as houses and buildings for the purpose of maintaining the quality and appearance of the wall surfaces under conditions of exposure to wind and rain and direct sunlight. Such a coating composition is required to have properties such as weather resistance against wind and rain, water resistance, light resistance, discoloration resistance, and adhesion to a substrate. In the field of paints, in recent years, water-based coating compositions have been promoted from the viewpoints of environmental impact, safety in painting work, and hygiene. As exterior coating compositions, coating compositions containing acrylic resin emulsions are widely used.

  When long-term weather resistance and durability are required, a coating composition containing an acrylic silicone resin-based emulsion that has been silicone-modified with a modifier having a specific silicone structure is used. In recent years, there has been a demand for further improvement in performance, and there is a need for a coating composition that exhibits excellent weather resistance and durability that can maintain an appearance for a long period of time even in harsh outdoor environments. .

  As an example of means for improving the performance such as weather resistance, for example, a means for increasing the proportion of the silicone structural component contained in the acrylic silicone resin emulsion can be considered. For example, Japanese Patent Application Laid-Open No. 2001-172340 (Patent Document 1) discloses a polyalkoxypolysiloxane obtained by reacting a polyalkoxypolysiloxane (a1) with a polymer compound (a2) having a functional group capable of reacting with the siloxane. A resin composition comprising a siloxane compound (A), a polymer (B ′) of a radical polymerizable unsaturated monomer (B) and a silicate oligomer (C) is described. It is described that this resin composition can improve the weather resistance of the coating film.

  As another example of means for improving performance such as weather resistance, for example, means for preparing a silicone resin emulsion in which a silicone resin is dispersed in an aqueous medium can be considered. For example, in Japanese Unexamined Patent Application Publication No. 2014-031413 (Patent Document 2), (i) the solvent component of an organic solvent solution of a silicone resin (A) synthesized in an organic solvent is replaced with a nonionic emulsifier (B). A silicone resin containing no organic solvent, comprising: a nonionic emulsifier solution of silicone resin (A); (ii) adding water to the nonionic emulsifier solution of silicone resin (A); and (iii) emulsifying. A method of making the emulsion is described.

  In JP 2003-213005 (Patent Document 3), a dispersion liquid mainly composed of an organopolysiloxane, a surfactant, and water is branched into at least two passages, and then the dispersion liquids are jetted. In a method for producing an organopolysiloxane emulsion that is made fine by collision, a method for producing an organopolysiloxane emulsion is described, wherein the dispersion is jetted and collided at a flow rate of 400 m / s or more.

JP 2001-172340 A JP 2014-031413 A JP 2003-213005 A

  In the method described in Patent Document 1, since a radical polymerizable unsaturated monomer is used in addition to the silicone structural component, the range in which the ratio of the silicone structural component can be increased is naturally limited. On the other hand, since the method described in Patent Document 2 is a method of dispersing the silicone resin itself, there is an advantage that an emulsion in which the content of the silicone resin is increased can be obtained. However, as a result of studies by the present inventors, it has been found that the storage stability of the emulsion may be inferior depending on the structure of the silicone resin in the technique described in Patent Document 2.

  An object of the present invention is to solve the above-described problems of the prior art. More specifically, an object of the present invention is to provide a method for producing an aqueous silicone resin emulsion for preparing a coating composition.

In order to solve the above problems, the present invention provides the following aspects.
[1]
A method for producing an aqueous silicone resin emulsion for preparing a coating composition, comprising the following steps:
The mixture of the silicone resin (A) and the organic solvent (B) and the mixture of the emulsifier (C) and the aqueous medium are mechanically emulsified, or the silicone resin (A), the organic solvent (B) and the emulsifier ( The mixture of C) and an aqueous medium are subjected to mechanical emulsification treatment to obtain an emulsified mixture, and the organic solvent (B) is at least partially removed from the emulsified step, and the obtained emulsified mixture is obtained. Obtaining a water-based silicone resin emulsion for preparing a composition, a desolvation step,
Including
The silicone resin (A) includes a branched organopolysiloxane having a weight average molecular weight in the range of 5,000 to 300,000,
The organic solvent (B) is an organic solvent that is mixed with the silicone resin (A) at an arbitrary ratio and has a solubility in water of 1 g / 100 g H ₂ O or a mixture thereof, or a mixture thereof. One type is conditional on having an azeotropic point with water,
The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is (A): (B) = 1: 2 to 1: 0.2, and the mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) contained in the emulsion mixture is: , (A) :( B) = 1: 2 to 1: 0.2
Method.
[2]
The method as described above, wherein the organic solvent (B) includes at least one selected from the group consisting of benzene, toluene, xylene, hexane and cyclohexane.
[3]
The method as described above, wherein the emulsifier (C) comprises an anionic surfactant.
[4]
The mechanical emulsification process in the emulsification step is one or more selected from the group consisting of a pressure shear stirring process, an opposing collision process, a collision stirring process, and a high-speed rotation stirring process.
The above method.
[5]
The above-mentioned method, wherein the aqueous silicone resin emulsion for preparing a coating composition has an average particle size in the range of 100 to 500 nm.
[6]
The branched organopolysiloxane has the following structure [R ¹ SiO _3/2 ] _m [R ² ₂ SiO] _n
Wherein R ¹ and R ² are each independently a hydroxyl group, a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms. ,
m is 1 to 1,000, n is 1 to 100, and m + n is in the range of 1 to 1,000. )
A branched organopolysiloxane having
The above method.
[7]
The viscosity of the mixture of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is in the range of 10 to 1,500 mPa · s. Is,
The above method.

  According to the production method of the present invention, it is possible to produce a silicone resin emulsion containing a branched organopolysiloxane that is fine and excellent in storage stability. By the production method of the present invention, an aqueous silicone resin emulsion for preparing a coating composition can be produced.

  The background to the present invention will be described. As shown in Patent Documents 2 and 3 above, various studies have been made in the preparation of silicone resin emulsions. On the other hand, as a result of investigations by the present inventors, it has been found that these conventional techniques have the following problems.

In the manufacturing method described in Patent Document 2, a nonionic emulsifier solution is substituted for a solvent component of an organic solvent solution of a silicone resin synthesized in an organic solvent to form a nonionic emulsifier solution of a silicone resin, and water is added to this to emulsify It is a manufacturing method characterized by doing. However, in this method, it has been found by experiments of the present inventors that, depending on the type of silicone resin, the particle size of the emulsion becomes large and the storage stability is inferior.
The manufacturing method described in Patent Document 3 is a manufacturing method characterized in that a dispersion containing an organopolysiloxane, a surfactant, and water is jetted and collided with a jetting collision type emulsifying device to form fine particles. . Since this method includes the step of jetting collision, when the viscosity of the dispersion is high, that is, when the viscosity of the organopolysiloxane is high, it may be difficult to perform jetting collision.

  The present inventors have aimed to develop a method capable of preparing an emulsion having a sufficiently fine particle diameter and excellent storage stability even when, for example, a high viscosity silicone resin is used. It was. And by emulsifying in the state of a mixture containing a silicone resin and an organic solvent, and then removing the organic solvent, even when using a high viscosity silicone resin, it has a sufficiently fine particle size, It has been found that a silicone resin emulsion having good storage stability can be prepared, and the present invention has been completed. Hereinafter, the production method of the present invention will be described.

The method for producing an aqueous silicone resin emulsion for preparing a coating composition includes the following steps;
The mixture of the silicone resin (A) and the organic solvent (B) and the mixture of the emulsifier (C) and the aqueous medium are mechanically emulsified, or the silicone resin (A), the organic solvent (B) and the emulsifier ( An emulsification step of mechanically emulsifying the mixture of C) and an aqueous medium to obtain an emulsified mixture;
And a step of at least partially removing the organic solvent (B) from the obtained emulsified mixture to obtain an aqueous silicone resin emulsion for preparing a coating composition.

Emulsification step The emulsification step involves mechanically emulsifying the mixture of the silicone resin (A) and the organic solvent (B) and the mixture of the emulsifier (C) and the aqueous medium, or the silicone resin (A), In this step, a mixture of an organic solvent (B) and an emulsifier (C) and an aqueous medium are mechanically emulsified to obtain an emulsified mixture. In the above production method, a mixture of the silicone resin (A) and the organic solvent (B) or a mixture of the silicone resin (A), the organic solvent (B) and the emulsifier (C) is used in the emulsification step, and The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) in the mixture before mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is (A ) :( B) = 1: 2 to 1: 0.2, and the mass ratio of the silicone resin (A) and the organic solvent (B) contained in the emulsion mixture (A) :( B) Satisfies the relationship of (A) :( B) = 1: 2 to 1: 0.2.

Silicone resin (A)
In the above method, the silicone resin (A) contains a branched organopolysiloxane having a weight average molecular weight in the range of 5,000 to 300,000. The weight-average molecular weight of the branched organopolysiloxane is preferably in the range of 5,000 to 100,000, and more preferably in the range of 5,000 to 50,000. When the weight average molecular weight is within the above range, it is possible to prepare a silicone resin emulsion having good storage stability. Furthermore, the coating film obtained from the coating composition prepared using the silicone resin emulsion has an advantage of having good weather resistance, water resistance and the like.

  A coating composition containing a branched organopolysiloxane has an advantage that a coating film having good coating strength can be formed. On the other hand, branched organopolysiloxanes have a relatively high viscosity. For this reason, when a silicone resin containing a branched organopolysiloxane is emulsified to prepare an aqueous coating composition, the preparation of the emulsion may be difficult due to the high viscosity. This is because when a silicone resin containing a branched organopolysiloxane having a high viscosity is emulsified, it is difficult to prepare a fine particle emulsion, and the storage stability of the obtained emulsion may be inferior.

  In the above method, in emulsification of the silicone resin (A), the emulsion before the mechanical emulsification treatment is emulsified in a state containing the silicone resin (A) and the organic solvent (B). This made it possible to prepare fine particle emulsions.

The branched organopolysiloxane is, for example, a compound having a structure represented by the following formula.
[R ¹ SiO _3/2 ] _m [R ² ₂ SiO] _n
In the above formula, R ¹ and R ² are each independently a hydroxyl group or a monovalent organic group having 1 to 20 carbon atoms, which may have a substituent as necessary.
m is in the range of 1 to 1,000;
n is in the range of 0-100.
In the above formula, m + n is preferably in the range of 1 to 1,000.

Specific examples of R ¹ and R ^{2 in} the above formula include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group. Group, hexadecyl group, octadecyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, etc., alkyl group having 1-20 carbon atoms; aryl having 6-20 carbon atoms, such as phenyl group, tolyl group, xylyl group, naphthyl group, etc. Group; an alkenyl group having 2 to 20 carbon atoms such as a vinyl group and an allyl group; a hydroxyl group; and the like. These groups may have a substituent as needed. Examples of the substituent include polar group-containing substituents such as halogen atoms, amino groups, acryloxyl groups, methacryloxyl groups, epoxy groups, mercapto groups, and carboxyl groups.
In the above formula, R ¹ and R ² are each independently a hydroxyl group, a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms. Is preferred.

The branched organopolysiloxane is a compound having a structure represented by the above formula. In the above formula, R ¹ and R ² are each independently a hydroxyl group and linear carbonization having 1 to 6 carbon atoms. A hydrogen group or an aromatic hydrocarbon group having 5 to 7 carbon atoms, m is 1 to 1,000, n is 1 to 100, and m + n is within a range of 1 to 1,000. More preferably.

In R ¹ and R ² in the above formula, 30 mol% or more is more preferably a methyl group, and 50 mol% or more is more preferably a methyl group.

In the above formula, m represents the number of [R ¹ SiO _3/2 ] units, and n represents the number of [R ² ₂ SiO] units. By containing [R ¹ SiO _3/2 ] units, a branched organopolysiloxane is obtained. Here, the molar ratio m: n of the above unit is preferably in the range of 2: 8 to 10: 0, more preferably in the range of 3: 7 to 10: 0, and 4: 6 to 10. : More preferably in the range of 0. In the said ratio, when the ratio of n is 8 or less, the hardness of the coating film obtained becomes a favorable range, and there exists an advantage which can obtain favorable durability.

  The branched organopolysiloxane can be prepared, for example, by hydrolyzing a silane compound such as chlorosilane or alkoxysilane and performing a condensation reaction. A commercially available product may be used as the branched organopolysiloxane. Examples of commercially available products include 804RESIN, 805RESIN, 840RESIN, SR-2400 manufactured by Toray Dow Corning; KR-220L, KR-242A, KR-251, KR-225, KR-271, KR manufactured by Shin-Etsu Chemical Co., Ltd. -282, X40-2406; SILRES K, SILRES KX, SILRES HK46, SILRES REN50, SILRES REN60, SILRES H62C, SILRES MES100 manufactured by Asahi Kasei Wacker Silicone.

  The silicone resin (A) may contain other organopolysiloxanes in addition to the branched organopolysiloxane. When the silicone resin (A) contains other organopolysiloxane, the amount of the branched organopolysiloxane in the silicone resin (A) is preferably in the range of 10 to 100% by mass, and 30 to 100% by mass. It is more preferable that it is within the range.

Examples of the organopolysiloxane that can be used as necessary include linear organopolysiloxane. Examples of the linear organopolysiloxane include compounds having a structure represented by the following formula.
R ³ — [R ⁴ ₂ SiO] _x —R ⁵
In the above formula, R ³ is a hydroxyl group, a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms,
R ⁴ is a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms,
R ⁵ is hydrogen, a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms,
x is in the range of 1 to 400.

  When the silicone resin (A) contains the linear organopolysiloxane in addition to the branched organopolysiloxane, the viscosity can be adjusted in the emulsification step, and the particle diameter of the resulting emulsion is adjusted. There are advantages that can be made.

Organic solvent (B)
The organic solvent (B) is an organic solvent that is mixed with the silicone resin (A) at an arbitrary ratio and has a solubility in water of 1 g / 100 gH ₂ O or less, or a mixture of such organic solvents. And it is on condition that at least 1 sort (s) of the said organic solvent has an azeotropic point with water. The mixing of the organic solvent (B) and the silicone resin (A) means mixing at an arbitrary ratio at 20 ° C. In the present specification, the “organic solvent having an azeotropic point with water” means an organic solvent that azeotropically shows a minimum azeotropic point when a mixture of water and the organic solvent is boiled by heating or the like. Further, "an organic solvent solubility in water is less than 1g / 100gH ₂ O" refers to solubility in 20 ° C..

  In the present specification, the “organic solvent having an azeotropic point with water” means an organic solvent that azeotropically shows a minimum azeotropic point when a mixture of water and the organic solvent is boiled by heating or the like. The organic solvent (B) preferably has an azeotropic point with water at 60 to 95 ° C. at normal pressure. When the azeotropic point of the organic solvent (B) is in the above range, there is an advantage that handling is easy in the emulsification step and the desolvation step.

Among the organic solvents (B), specific examples of organic solvents having a solubility in water of 1 g / 100 gH ₂ O or less and an azeotropic point with water include, for example, benzene, toluene, xylene, and hexane. Organic solvents containing one or more of hydrocarbon solvents such as cyclohexane. The organic solvent (B) is more preferably one or more selected from the group consisting of benzene, toluene, xylene, hexane and cyclohexane, and is selected from the group consisting of benzene, toluene, hexane and cyclohexane. More preferably, it is one or more.

  By using the organic solvent, in the desolvation step after obtaining the emulsified mixture, it can be easily distilled off by azeotropy with water. Thereby, the solvent odor is reduced, and there is an advantage that an aqueous silicone resin emulsion having no flash point can be obtained.

Among the organic solvents (B), the organic solvent having a water solubility of 1 g / 100 gH ₂ O or less and having no azeotropic point with water is, for example, an aromatic organic solvent having 10 to 20 carbon atoms. And an organic solvent that does not have an azeotropic point with water and an organic solvent that has 8 to 20 carbon atoms and does not have an azeotropic point with water.

Emulsifier (C)
The emulsifier (C) used in the emulsification step is not particularly limited, and for example, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, polyoxyalkylene alkenyl ether sulfate ester, alkyl diphenyl ether sulfate ester salt, polyoxyethylene alkyl Anionic surfactants such as ether acetates, alkylbenzene sulfonates, alkenyl succinates;
Cationic surfactants such as quaternary ammonium salts;
Glycerin fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene Nonionic surfactants such as hydrogenated castor oil, polyethylene glycol fatty acid ester, alkyl glyceryl ether, alkyl alkanolamide, alkyl polyglucoside;
Amphoteric surfactants such as alkylbetaines, imidazoline-type betaines, alkylamine oxides, alkylamidopropylbetaines, alkylhydroxysulfobetaines;
Etc. can be used.
These emulsifiers (C) may use only 1 type and may use 2 or more types together.

The emulsifier (C) preferably contains an anionic surfactant. By using an emulsifier (C) containing an anionic surfactant, an emulsified mixture and an aqueous silicone resin emulsion having an average particle diameter in a suitable range can be obtained, and an aqueous silicone resin emulsion excellent in storage stability There are advantages that you can get.
Preferred anionic surfactants include, for example, polyoxyethylene alkyl ether sulfate ester salts such as New Coal 707SN, New Coal 714SN, New Coal 780SF, New Coal 2308SF (all manufactured by Nippon Emulsifier Co., Ltd.), polyoxyalkylene alkenyl ether sulfuric acid. Latemul PD-104 (manufactured by Kao Corporation), Aqualon KH-1025 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Neogen S-20F (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), neoperex G-65, Neoperex G-25 (all manufactured by Kao Corporation), alkyl diphenyl ether sulfate ester salt, Perex SS-L, Perex SS-H (all manufactured by Kao Corporation), Latemul, an alkenyl succinate ASK, Lattemul SK (all manufactured by Kao Corporation), and the like.

  Moreover, the aspect containing an anionic surfactant and a nonionic surfactant is mentioned as an example of the said emulsifier (C).

  The amount of the emulsifier (C) is preferably 0.5 to 10 parts by mass, and 2.5 to 10 parts by mass with respect to 100 parts by mass of the resin solid content of the silicone resin (A). More preferably. When the amount of the emulsifier (C) is within the above range, the average particle size can be reduced, and when the aqueous coating composition is prepared using the obtained silicone resin emulsion, There is an advantage that can be secured.

  In this specification, an aqueous medium is a medium consisting essentially of water. In some cases, the aqueous medium may contain a water-compatible organic solvent such as alcohol in the range of several mass%.

  In one embodiment of the emulsification step, first, a mixture of the silicone resin (A) and the organic solvent (B), and a mixture of the emulsifier (C) and the aqueous medium are prepared. Subsequently, these mixtures are subjected to a mechanical emulsification treatment to obtain an emulsified mixture. In another embodiment of the emulsification step, by preparing a mixture of the silicone resin (A), the organic solvent (B) and the emulsifier (C), further mixing an aqueous medium and performing a mechanical emulsification treatment, An emulsified mixture is obtained. These mixtures can be prepared by mixing using a stirrer usually used in the paint field. A commercially available product may be used as the mixture of the silicone resin (A) and the organic solvent (B).

  The viscosity of the mixture of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is in the range of 10 to 1,500 mPa · s. It is preferable that it is in the range of 10 to 700 mPa · s, more preferably in the range of 10 to 200 mPa · s. Since the viscosity of the branched organopolysiloxane having a weight average molecular weight in the range of 5,000 to 300,000 is, for example, a high viscosity exceeding 1,500 mPa · s, the viscosity of the silicone resin (A) is also high. It gets higher again. Here, by setting the viscosity of the mixture of the silicone resin (A) and the organic solvent (B) in the mixture before mechanical emulsification used in the emulsification step within the above range, an average particle diameter in a favorable range is obtained. There exists an advantage which can prepare the silicone resin emulsion which has.

  In the above-described method, the mixture before the mechanical emulsification treatment including the silicone resin (A) and the organic solvent (B) in the emulsification step is performed by the mass ratio (A) :( B) Mass ratio (A) of the silicone resin (A) and the organic solvent (B) contained in the emulsion mixture (that is, after the emulsion) satisfying the relationship of 1: 2 to 1: 0.2 : (B) satisfies the relationship of (A) :( B) = 1: 2 to 1: 0.2. When the silicone resin (A) contains the branched organopolysiloxane because the mass ratio of the silicone resin (A) and the organic solvent (B) is within the above range both before and after the emulsification. Even if it exists, a favorable silicone resin emulsion can be prepared.

  In the above production method, the mass ratio (A) of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) (that is, before emulsification). : (B) satisfies the above range, and the mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) contained in the emulsion mixture (that is, after the emulsion) is within the above range. Satisfaction means that a certain amount of organic solvent is present both before and after emulsification. Therefore, for example, the production method in which the content of the organic solvent is less than the above range by distilling off the organic solvent before emulsification is not included in the production method in the present invention.

  The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) in the mixture (before emulsification) containing the silicone resin (A) and the organic solvent (B) before mechanical emulsification treatment is: It is preferable that (A) :( B) = 1: 1.5 to 1: 0.2. The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) contained in the emulsified mixture (after emulsification) is (A) :( B) = 1: 1.5. It is preferably ˜1: 0.2.

More specifically, the method for obtaining the emulsified mixture can be performed, for example, by the following procedure.
Procedure 1: A procedure in which the total amount of the mixture of the silicone resin (A) and the organic solvent (B) is once mixed with the total amount of the mixture of the emulsifier (C) and the aqueous medium, and then mechanically emulsified.
Procedure 2: The total amount of the mixture of silicone resin (A) and organic solvent (B) is subjected to mechanical emulsification treatment by first adding a part of the mixture of emulsifier (C) and aqueous medium, and then the rest A procedure in which a mixture of an emulsifier (C) and an aqueous medium is added to perform a mechanical emulsification treatment.
Procedure 3: A procedure in which the emulsifier (C) is once mixed with the total amount of the mixture of the silicone resin (A) and the organic solvent (B), and then mechanical emulsification treatment is performed while adding an aqueous medium.
Procedure 4: A part of the mixture of the silicone resin (A) and the organic solvent (B) and a part of the mixture of the emulsifier (C) and the aqueous medium are added first to perform a mechanical emulsification treatment, Procedure for adding the remaining mixture and performing mechanical emulsification.
Procedure 5: A mechanical emulsification treatment is performed by first adding a part of the mixture of the silicone resin (A) and the organic solvent (B) and the total amount of the mixture of the emulsifier (C) and the aqueous medium, and then the remaining silicone. A procedure in which a mixture of the resin (A) and the organic solvent (B) is added to perform a mechanical emulsification treatment.
Procedure 6: A part of the mixture of the silicone resin (A) and the organic solvent (B) is added to and mixed with the total amount of the mixture of the emulsifier (C) and the aqueous medium, and then the remaining silicone resin (A) and A procedure in which a mixture of organic solvent (B) is added to perform mechanical emulsification.

  The said mechanical emulsification process in an emulsification process means the emulsification process performed using a physical convection. Specific examples of the mechanical emulsification process include, for example, a pressure shear stirring process, an opposing collision process, a collision stirring process, and a high-speed rotation stirring process.

The pressure shear stirring process is a process of performing shear stirring under pressure conditions. As a pressurization condition, the pressurization condition of 10-100 MPa is mentioned, for example.
The opposing collision process is a process for refining particles such as an emulsion by applying a high pressure to a liquid that is a mixture and causing the liquid to collide and pass in a processing container (for example, a homovalve). As a pressurization condition, the pressurization condition of 10-100 MPa is mentioned, for example. As a specific example of the opposing collision process, for example, a homogenizer process under a pressure of 10 to 100 MPa is given. As a specific example of the facing collision process, for example, a facing collision process using a high-pressure homogenizer can be cited.
The collision agitation process is a process in which the objects to be mixed are divided into two or more, and each is agitated by being injected and collided with a high pressure (for example, a pressure of 10 to 100 MPa). The opposing collision process and the collision agitation process can be suitably used as a method for processing a relatively large amount of raw materials because the injection collision can be continuously performed. Specific examples of the collision stirring process include a collision stirring process using a microfluidizer.
The high-speed rotation stirring process is a stirring process by rotating the stirring bar at a high speed. As a high-speed rotation condition, the aspect which stirs at 5,000-30,000 rpm is mentioned, for example. As a specific example of the high-speed rotation stirring process, for example, a high-speed rotation stirring process using Claremix, Claremix W Motion (M Technique Co., Ltd.) or the like can be mentioned.

  For example, an emulsion having an average particle diameter in the range of 100 to 500 nm can be prepared by subjecting the mixture before the mechanical emulsification treatment including the silicone resin (A) and the organic solvent (B) to mechanical emulsification treatment. .

Desolvation Step An aqueous silicone resin emulsion for preparing a coating composition can be obtained by at least partially removing the organic solvent (B) from the emulsion mixture obtained in the emulsification step (desolvation step). As a method for removing the organic solvent (B), a general desolvation method known to those skilled in the art can be used. As an example of the solvent removal method, for example, a method of removing the organic solvent (B) at least partially by heating and / or reducing pressure in a general stirred solvent removal tank, a falling film method or a rotary evaporator, or the like can be mentioned.

  In the above production method, even a silicone resin containing a branched organopolysiloxane can be well emulsified with a sufficiently fine particle size. And by the said manufacturing method, the silicone resin emulsion excellent in the storage stability suitable for preparation of a coating composition can be obtained. The average particle size of the silicone resin emulsion obtained by the above method is preferably in the range of 100 to 500 nm, and more preferably in the range of 100 to 400 nm.

  The average particle diameter in the present specification is an average particle diameter determined by a dynamic light scattering method, and specifically, is measured using an electrophoretic light scattering photometer ELSZ series (manufactured by Otsuka Electronics Co., Ltd.) or the like. be able to.

  The silicone resin emulsion produced by the above method is a silicone resin emulsion in which a silicone resin containing the branched organopolysiloxane is dispersed. Therefore, the above-mentioned silicone resin emulsion can be suitably used in the preparation of an aqueous coating composition. The silicone resin emulsion can be mixed with a pigment or an additive usually used in the paint field to prepare an aqueous paint composition. This is because the silicone resin containing the branched organopolysiloxane can provide a coating composition with good coating performance. Examples of the water-based paint composition include exterior paint compositions that require good weather resistance, water resistance, light resistance, durability, storage stability, and the like.

  The water-based coating composition includes a silicone resin emulsion produced by the above-described method, a pigment used as necessary, and an additive used as necessary (for example, a viscosity modifier, a filler, a dispersant, an ultraviolet absorber, Light stabilizers, antioxidants, antifreezing agents, antialgae agents, antifoaming agents, film-forming aids, antiseptics, fungicides, etc.).

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Example 1
Production of Silicone Resin Emulsion To a stainless steel container, 25 parts by mass of Latem PD-104 (manufactured by Kao Corporation, anionic emulsifier; component content: 20% by mass) and 152 parts by mass of ion-exchanged water are added as an emulsifier (C-1). SR-2400 (made by Toray Dow Corning Co., Ltd., branched organopolysiloxane; weight average molecular weight: 20,000, viscosity: 15 mPa · s, solid content concentration: 50% by mass, with stirring as silicone resin (A-1) 200 parts by mass of organic solvent (B-1): toluene) was added, and stirred for 15 minutes at 1,500 rpm using a disper (total amount: 377 parts by mass, solid content: 105 parts by mass).
Subsequently, SN777 (manufactured by San Nopco, defoaming agent) 0.057 parts by mass was added, and then treated with high pressure homogenizer H20-H2 (manufactured by Sanwa Engineering Co., Ltd.) at 35 MPa (mechanical emulsification treatment; Emulsification step), 377 parts by mass of the emulsion mixture was obtained.
Further, the emulsified mixture was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water (desolvation step), and the silicone resin emulsion 1 for coating composition preparation was removed. 247 parts by mass (solid content concentration: 42% by mass) was obtained. The average particle diameter of the obtained silicone resin emulsion 1 for preparing a coating composition was 345 nm.
Moreover, it was less than 0.1 mass% when content of the organic solvent (toluene (B-1)) in the obtained silicone resin emulsion 1 was measured.

Example 2
246 parts by mass (solid content concentration: solid content concentration: same as Example 1) except that the mechanical emulsification treatment was performed at 100 MPa using a microfluidizer M-110EH (Paulec). 43 mass%) was obtained. The average particle diameter of the obtained silicone resin emulsion 2 for preparing a coating composition was 252 nm.

Example 3
To a stainless steel container, 25 parts by mass of emulsifier (C-1) and 202 parts by mass of ion-exchanged water are added, and X40-2406M (Shin-Etsu Chemical Co., Ltd., branched organopolysiloxane) is added as a silicone resin (A-2) while stirring. Weight average molecular weight: 40,000, Viscosity: 20 mPa · s, Solid content concentration: 40% by mass, Organic solvent (B-2): Xylene) 250 parts by mass were added, and stirred at 1,500 rpm for 15 minutes using a disper. (Total amount 477 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and obtained 477 mass parts of the emulsion mixture.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-2) was distilled off together with water, and 247 parts by mass (solid content concentration) of the silicone resin emulsion 3 for coating composition preparation : 42% by mass).
The average particle diameter of the obtained silicone resin emulsion 3 for preparing a coating composition was 320 nm.

Example 4
To a stainless steel container, 25 parts by mass of emulsifier (C-1) and 185 parts by mass of ion-exchanged water are added, and while stirring, 804RESIN (manufactured by Dow Corning Toray, branched organopolysiloxane; weight) as a silicone resin (A-3) Average molecular weight: 5,000, viscosity: 30 mPa · s, solid content concentration: 60% by mass, organic solvent (B-1): 167 parts by mass of toluene) were added, and the mixture was stirred at 1,500 rpm for 15 minutes using a disper. (Total amount 377 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and obtained 377 mass parts of the emulsion mixture.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water, and 245 parts by mass (solid content concentration) of the silicone resin emulsion 4 for coating composition preparation : 43% by mass).
The average particle diameter of the obtained silicone resin emulsion 4 for preparing a coating composition was 310 nm.

Example 5
In a stainless steel container, 140 parts by mass of silicone resin (A-1) and YF-3800 (manufactured by Momentive Performance Materials, Inc., linear organopolysiloxane) as silicone resin (A-4); weight average molecular weight: 4, 000, viscosity 70 mPa · s, solid content concentration: 100% by mass) was mixed to obtain 170 parts by mass of a mixture. The viscosity of the obtained mixture was 51 mPa · s.
In another stainless steel container, 25 parts by mass of emulsifier (C-1) and 182 parts by mass of ion-exchanged water were added, 170 parts by mass of the above mixture was added while stirring, and the mixture was stirred at 1,500 rpm for 15 minutes using a disper ( (Total amount 377 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and obtained 377 mass parts of the emulsion mixture.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water, and 244 parts by mass (solid content concentration) of the silicone resin emulsion 5 for coating composition preparation : 43% by mass).
The average particle diameter of the obtained silicone resin emulsion 5 for preparing a coating composition was 350 nm.

Example 6
In a stainless steel container, 140 parts by mass of silicone resin (A-1) and 30 parts by mass of silicone resin (A-4) were mixed to obtain 170 parts by mass of a mixture. The viscosity of the obtained mixture was 51 mPa · s.
In another stainless steel container, 10 parts by mass of emulsifier (C-1), 3 parts by mass of Latemul PD-430 (Kao Corporation, nonionic; component content: 100% by mass) as an emulsifier (C-3), and ion exchange 194 parts by mass of water was added, 170 parts by mass of the mixture was added while stirring, and the mixture was stirred for 15 minutes at 1,500 rpm using a disper (total amount of 377 parts by mass, solid content of 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and obtained 377 mass parts of the emulsion mixture.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water, and 247 parts by mass (solid content concentration) of the silicone resin emulsion 6 for preparing a coating composition. : 42% by mass).
The average particle diameter of the obtained silicone resin emulsion 6 for preparing a coating composition was 365 nm.

Example 7
In a stainless steel container equipped with a high shear disperser, 190 parts by mass of silicone resin (A-1) and KR-220LP (made by Shin-Etsu Chemical Co., Ltd., branched organopolysiloxane) as silicone resin (A-5); weight average molecular weight: 900, powder shape, solid content concentration: 100% by mass) were mixed to obtain 195 parts by mass of a mixture. The viscosity of the obtained mixture was 25 mPa · s.
To the mixture, 10 parts by weight of PELEX SS-H (manufactured by Kao Corporation, anionic; component content: 50% by mass) as an emulsifier (C-2) was added and stirred for 30 minutes at 8,000 rpm. 172 parts by mass of ion-exchanged water was added to obtain an emulsified mixture (total amount: 377 parts by mass, solid content: 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it heated at 55 degreeC, desolvated under reduced pressure, the organic solvent (B-1) was distilled off with water, and the silicone resin for coating composition preparation 244 mass parts (solid content concentration: 43 mass%) of the emulsion 7 were obtained.
The average particle size of the obtained silicone resin emulsion 7 for preparing a coating composition was 390 nm.

Example 8
In a stainless steel container, 140 parts by mass of silicone resin (A-1), 30 parts by mass of silicone resin (A-4), and 40 parts by mass of Cactus solvent P-150 (manufactured by JXTG Energy) as an organic solvent (B-3). The mixture was mixed to obtain 210 parts by mass of the mixture. The viscosity of the obtained mixture was 30 mPa · s.
In another stainless steel container, 25 parts by mass of emulsifier (C-1) and 142 parts by mass of ion-exchanged water were added, 210 parts by mass of the mixture was added with stirring, and the mixture was stirred at 1,500 rpm for 15 minutes using a disper ( (Total amount 377 parts by mass, solid content 105 parts by mass).
Subsequently, SN7777 (manufactured by San Nopco, defoaming agent) 0.057 parts by mass was added, and then treated with a high pressure homogenizer H20-H2 (manufactured by Sanwa Engineering Co., Ltd.) at 35 MPa, and 377 masses of the emulsified mixture. Got a part.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water, and 247 parts by mass (solid content concentration) of the silicone resin emulsion 8 for preparing a coating composition : 42% by mass).
The average particle diameter of the obtained silicone resin emulsion 8 for preparing a coating composition was 385 nm.

Example 9
To a stainless steel container, 10 parts by mass of emulsifier (C-3) and 172 parts by mass of ion-exchanged water are added, 200 parts by mass of silicone resin (A-1) is added with stirring, and 15 minutes at 1,500 rpm using a disper. The mixture was stirred (total amount 382 parts by mass, solid content 110 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering), and obtained 382 mass parts of the emulsion mixture.
Furthermore, the emulsified mixture was heated to 55 ° C., desolvated under reduced pressure, the organic solvent (B-1) was distilled off together with water, and 252 parts by mass (solid form of silicone resin emulsion 9 for preparing a coating composition) (Min. Concentration: 44% by mass).
The average particle diameter of the obtained silicone resin emulsion 9 for preparing a coating composition was 495 nm.

Comparative Example 1
In a stainless steel container equipped with a desolvation device, 140 parts by mass of silicone resin (A-1), 30 parts by mass of silicone resin (A-4) and 15 parts by mass of organic solvent (B-3) are mixed, and 185 parts by mass of the mixture Got. The obtained mixture was heated to 75 ° C., and the solvent was removed under reduced pressure to distill off 70 parts by mass of the organic solvent (B-1). The viscosity of the mixture was 1,900 mPa · s.
In another stainless steel container, 25 parts by mass of emulsifier (C-1) and 93 parts by mass of ion-exchanged water were added, 115 parts by mass of the above mixture was added while stirring, and the mixture was stirred at 1,500 rpm for 15 minutes using a disper ( (Total amount 233 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and 233 mass parts (solid content concentration: 43) of the silicone resin emulsion 11 Mass%).
The average particle diameter of the obtained silicone resin emulsion 11 was 1,780 nm. Moreover, when this silicone resin emulsion 11 was left still for one day, separation and sedimentation occurred.

Comparative Example 2
To a stainless steel container equipped with a disper, 25 parts by mass of emulsifier (C-1) and 93 parts by mass of ion-exchanged water are added, and 200 parts by mass of silicone resin (A-1) are mixed while stirring at 1,500 rpm. The mixture was stirred for a minute (total amount: 318 parts by mass, solid content: 105 parts by mass).
The average particle diameter of the obtained silicone resin emulsion 12 was 10,000 nm or more. Moreover, when this silicone resin emulsion 12 was left still for one day, separation and sedimentation occurred.

Comparative Example 3
In a stainless steel container equipped with a solvent removal apparatus, 200 parts by mass of silicone resin (A-1) and 100 parts by mass of butoxypropanol as an organic solvent (b-1) were mixed to obtain 300 parts by mass of a mixture. The obtained mixture was heated to 75 ° C., desolvated under reduced pressure to distill off 100 parts by mass of the organic solvent (B-1), and 200 parts by mass of a resin mixture containing only (b-1) as the organic solvent. Got. The viscosity of the mixture was 17 mPa · s.
In another stainless steel container, 25 parts by mass of emulsifier (C-1) and 152 parts by mass of ion-exchanged water were added, 200 parts by mass of the above mixture was added while stirring, and the mixture was stirred at 1,500 rpm for 15 minutes using a disper ( (Total amount 377 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777, it processed by 35 Mpa using the high voltage | pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and the silicone resin emulsion 377 mass part (105 mass parts of solid content) was carried out. Obtained.
Further, the emulsion was heated to 55 ° C., desolvated under reduced pressure, 130 parts by mass of water and the organic solvent (b-2) were distilled off, and 247 parts by mass (solid content concentration) of the silicone resin emulsion 13 : 42% by mass).
The average particle diameter of the obtained silicone resin emulsion 13 was 315 nm, but when it was allowed to stand for 30 days, separation and precipitation occurred.

Comparative Example 4
To a stainless steel container, 25 parts by mass of emulsifier (C-1) and 93 parts by mass of ion-exchanged water are added, 200 parts by mass of silicone resin (A-1) is added with stirring, and 15% at 1,500 rpm using a disper. The mixture was stirred for a minute (total amount: 318 parts by mass, solid content: 105 parts by mass).
Next, 0.057 parts by mass of SN-777 (manufactured by San Nopco, defoaming agent) was added, and then treated with 35 MPa using a high-pressure homogenizer H20-H2 (manufactured by Sanwa Engineering Co., Ltd.). 318 parts by mass were obtained.
The average particle diameter of the obtained silicone resin emulsion 14 was 360 nm.

Comparative Example 5
A mixture of 200 parts by mass of silicone resin (A-1) and 150 parts by mass of (B-3) mixed in advance while adding 25 parts by mass of emulsifier (C-1) and 302 parts by mass of ion-exchanged water to a stainless steel container. And stirred for 15 minutes at 1,500 rpm using a disper (total amount 677 parts by mass, solid content 105 parts by mass).
Subsequently, after adding 0.057 mass part of SN-777 (the Sannopco company make, antifoamer), it processed by 35 Mpa using the high pressure homogenizer H20-H2 (made by Sanwa Engineering Co., Ltd.), and 677 mass of the emulsified mixture. Got a part.
Further, the emulsified mixture was heated to 55 ° C., the solvent was removed under reduced pressure, the organic solvents (B-1) and (B-3) were distilled off together with water, and the silicone resin emulsion 15 for preparing a coating composition was removed. Of 397 parts by mass (solid content concentration: 26% by mass) was obtained. The average particle diameter of the obtained silicone resin emulsion 15 for preparing a coating composition was 310 nm.

  The silicone resin (A) used in each example and comparative example is as shown in Table 1 below.

The m / n value in the silicone resin is R ¹ SiO _3/2 , R determined from a weight average molecular weight measured by gel permeation chromatography HLC-8220GPC (manufactured by Tosoh Corporation) and 29Si-NMR DPX400 (manufactured by Bruker). ^It calculated from the composition ratio of ² ₂ SiO.

Moreover, the organic solvent (B) and the emulsifier (C) used by each Example and the comparative example are as follows.
Organic solvent (B-1): Toluene (azeotropic point with water: 85 ° C., solubility in water: 0.047 g / 100 g H ₂ O)
Organic solvent (B-2): xylene (azeotropic point with water: 94.5 ° C., solubility in water: 0 g / 100 g H ₂ O)
Organic solvent (B-3): Cactus solvent P-150 (manufactured by JXTG Energy, azeotropic point with water: none, solubility in water: 0.04 g / 100 g H ₂ O)
Organic solvent (b-1): butoxypropanol (azeotropic point with water: none, solubility in water: 5.5 g / 100 g H ₂ O)
Emulsifier (C-1): Latem PD-104 (manufactured by Kao Corporation, anionic, component content: 20% by mass)
Emulsifier (C-2): Perex SS-H (manufactured by Kao Corporation, anionic, component content: 50% by mass)
Emulsifier (C-3): Latem PD-430 (manufactured by Kao Corporation, nonionic properties, component content: 100% by mass)

  The following evaluation was performed using the emulsified mixture and silicone resin emulsion prepared in the above Examples and Comparative Examples. The obtained evaluation results are shown in Table 2 below.

Viscosity measurement The viscosity of the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is a TVB-10 viscometer (TVB-10H, manufactured by Toki Sangyo Co., Ltd .; measurement temperature: 25 ° C., Rotational speed: 60 rpm).

Particle size measurement The average particle size of the emulsified mixture and the silicone resin emulsion is diluted with ion-exchanged water so that the signal level of the aqueous dispersion is appropriate using an electrophoretic light scattering photometer ELSZ (manufactured by Otsuka Electronics Co., Ltd.). And measured.

State of Silicone Resin Emulsion The state of the silicone resin emulsion was evaluated by the following criteria by visually observing the state after standing for 1 day at room temperature after filtering with a 200 mesh filter.
○: No separation / sedimentation ×: Separation / sedimentation occurs

Odor Evaluation The odor of the silicone resin emulsion was evaluated according to the following criteria.
○: No odor △: Somewhat odor ×: Clearly odor

Measurement of residual amount of solvent The residual amount of toluene (B-1) or xylene (B-2) contained in the silicone resin emulsion was measured by gas chromatograph GC-2014 (manufactured by Shimadzu Corporation).

Measurement of Flash Point The flash point of the silicone resin emulsion was measured according to JIS K 2265-2, using a seta-sealed flash point measuring instrument Setaflash 33000-0 (manufactured by Stanhope-Seta).

Evaluation of Storage Stability The silicone resin emulsions obtained in the above Examples and Comparative Examples were filtered through a 200 mesh filter and then allowed to stand at 40 ° C. for 3 months. The state of the silicone resin emulsion after standing was visually observed and evaluated according to the following criteria.
○: Separation / sedimentation does not occur ×: Separation / sedimentation occurs

All of the silicone resin emulsions prepared in the examples had an average particle diameter in the range of 100 to 500 nm, and had good storage stability.
Comparative Example 1 is an example in which the organic solvent (B) is removed before emulsification, and includes both branched organopolysiloxane and linear organopolysiloxane as the silicone resin (A). . The silicone resin emulsion prepared in this example had an average particle size exceeding 500 nm and was inferior in storage stability.
Comparative Example 2 is an example prepared by the same procedure as Example 1 except that a disper was used in place of the high-pressure homogenizer and no solvent removal step was used. The silicone resin emulsion prepared in this example had an average particle size exceeding 500 nm and was inferior in storage stability.
Comparative Example 3 uses an organic solvent whose solubility in water exceeds 1 g / 100 gH ₂ O as the organic solvent, and removes the organic solvent (B) before emulsification to produce butoxypropanol (b-1). It is an example prepared by substituting. In this example, a large amount of the hydrophilic organic solvent remained even after the solvent removal step, and the storage stability was poor.
Comparative Example 4 is an example prepared in the same manner as in Example 1 except that it does not have a solvent removal step. The silicone resin emulsion prepared in this example has a strong solvent odor, has a flash point, and needs to be handled as a hazardous material, so it is not suitable as an emulsion for preparing an aqueous coating composition. It was.
Comparative Example 5 is an example prepared by the same procedure as Example 1 except that 150 parts by mass of the organic solvent (B-3) was added before emulsification. The silicone resin emulsion prepared in this example was somewhat odorous and had a lower flash point than the examples. Moreover, since the amount of solvent removal in the solvent removal process is large, it took time for the solvent removal process.

Production of aqueous coating composition 40 parts by mass of the silicone resin emulsion obtained in Example 1, 0.15 parts by mass of 25% ammonia water, and 37 parts by mass of tap water were mixed. Next, 1.23 parts by mass of DIBUTYL TIN OXIDE (manufactured by Nitto Kasei Co., Ltd.) was added and mixed as a curing catalyst. Furthermore, 2 parts by mass of Primal ASE-60 (manufactured by Dow Chemical Co., Ltd.) as an alkali swelling type thickener was added and mixed to obtain an aqueous silicone coating composition.
The obtained aqueous silicone coating composition was spray-coated and dried at 160 ° C. for 3 minutes to obtain a silicone coating film.

Reference example 1
Preparation of silicone resin emulsion using silicone resin (A) containing no branched organopolysiloxane, and preparation of aqueous coating composition YF-3800 (momentive) as silicone resin (A-4) as silicone resin (A) Manufactured, linear organopolysiloxane) A silicone resin emulsion was prepared in the same manner as in Example 1 except that only 100 parts by mass was used. The average particle diameter of the obtained silicone resin emulsion was 360 nm.
Using the obtained silicone resin emulsion, an aqueous silicone coating composition was obtained in the same manner as described above.
When the obtained aqueous silicone coating composition was spray-coated and dried at 160 ° C. for 3 minutes, although the formation of the coating film was confirmed, the toughness of the formed coating film was low and it had a performance that could withstand practical use. Not confirmed. From this result, it can be seen that the silicone resin emulsion is not suitable as an emulsion for preparing a coating composition.

  According to the production method of the present invention, it is possible to produce a silicone resin emulsion containing a branched organopolysiloxane that is fine and excellent in storage stability. By the production method of the present invention, an aqueous silicone resin emulsion for preparing a coating composition can be produced.

Claims (6)

A method for producing an aqueous silicone resin emulsion for preparing a coating composition, comprising the following steps:
The mixture of the silicone resin (A) and the organic solvent (B) and the mixture of the emulsifier (C) and the aqueous medium are mechanically emulsified, or the silicone resin (A), the organic solvent (B) and the emulsifier ( The mixture of C) and an aqueous medium are subjected to mechanical emulsification treatment to obtain an emulsified mixture, and the organic solvent (B) is at least partially removed from the emulsified step, and the resulting emulsified mixture is obtained. Obtaining a water-based silicone resin emulsion for preparing a composition, a desolvation step,
Including
The silicone resin (A) includes a branched organopolysiloxane having a weight average molecular weight in the range of 5,000 to 300,000,
The organic solvent (B) is an organic solvent that is mixed with the silicone resin (A) at an arbitrary ratio and has a solubility in water of 1 g / 100 gH ₂ O or less, or a mixture thereof, and at least the organic solvent One type is conditional on having an azeotropic point with water,
The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is (A): The mass ratio (A) :( B) of the silicone resin (A) and the organic solvent (B) included in the emulsion mixture satisfying the relationship (B) = 1: 2 to 1: 0.67 is: , (a) :( B) = 1: 2~1: meet the 0.67 relationship, and
The viscosity of the mixture of the silicone resin (A) and the organic solvent (B) in the mixture before the mechanical emulsification treatment containing the silicone resin (A) and the organic solvent (B) is in the range of 10 to 1,500 mPa · s. Is,
Method.   The method according to claim 1, wherein the organic solvent (B) includes at least one selected from the group consisting of benzene, toluene, xylene, hexane, and cyclohexane.   The method of claim 1 or 2, wherein the emulsifier (C) comprises an anionic surfactant. The mechanical emulsification process in the emulsification step is one or more selected from the group consisting of a pressure shear stirring process, an opposing collision process, a collision stirring process, and a high-speed rotation stirring process.
The method according to claim 1.   The method according to any one of claims 1 to 3, wherein the water-based silicone resin emulsion for preparing a coating composition has an average particle diameter in the range of 100 to 500 nm. The branched organopolysiloxane has the following structure [R ¹ SiO _3/2 ] _m [R ² ₂ SiO] _n
Wherein R ¹ and R ² are each independently a hydroxyl group, a linear hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 5 to 7 carbon atoms. ,
m is 1 to 1,000, n is 1 to 100, and m + n is in the range of 1 to 1,000. )
A branched organopolysiloxane having
The method according to claim 1.