Production method of aqueous solution or aqueous dispersion including polysiloxane-based resin

Abstract

To provide a production method capable of obtaining an aqueous solution or an aqueous dispersion including a high molecular weight polysiloxane-based resin excellent in water resistance and weather resistance when making a coated film.SOLUTION: The production method has the steps of: subjecting a specific silane compound to dehydration condensation in the presence of water and a dehydration condensation catalyst to obtain a first mixture; subjecting a dehydration condensate contained in the first mixture and a specific monomer to radical polymerization in the presence of an organic solvent soluble to an initiator and water to obtain a second mixture; dispersing or dissolving the second mixture to water to obtain a third mixture; and removing the organic solvent contained in the third mixture by devolatilization.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an aqueous solution or aqueous dispersion containing a polysiloxane-based resin.

Background Art

[0002] Polysiloxane grafted with acrylic having organic properties (hereinafter sometimes referred to as "polysiloxane-based resin") has interesting properties as an inorganic-organic hybrid resin, and thus has attracted industrial attention.

[0003] Among them, in the field of paints, water-based paints containing polysiloxane-based resins are less harmful to the human body and the environment, and thus are becoming more widespread in the market, and the needs for various applications are increasing. For example, Patent Document 1 discloses a method for producing a solution or dispersion in which water is a medium and which contains a polysiloxane-based resin, the method having a condensation step of hydrolyzing and dehydrating and condensing a silane compound using a neutral salt as a catalyst.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above-described conventional techniques had room for improvement from the viewpoint of obtaining an aqueous solution or aqueous dispersion containing a high-molecular-weight polysiloxane-based resin. Further, a coating film obtained from such an aqueous solution or aqueous dispersion preferably has excellent water resistance and weather resistance.

[0006] One aspect of the present invention aims to realize a production method for obtaining an aqueous solution or an aqueous dispersion containing a high molecular weight polysiloxane resin, which is excellent in water resistance and weather resistance when formed into a coating film.

Means for Solving the Problems

[0007] In order to solve the above problems, a production method for an aqueous solution or an aqueous dispersion containing a polysiloxane resin according to one aspect of the present invention includes a silane compound (A) having a radically polymerizable unsaturated group and a hydrolyzable silyl group, and a silane compound (B) represented by the following general formula (I) other than the silane compound (A): R 1 n -Si-(OR 2 ) 4-n ···(I) (In the formula, each R 1 is independently an alkyl group having 1 to 10 carbon atoms, or an unsubstituted or substituted aryl group, each R 2 is independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 0 to 3.) By subjecting the silane compound (A) and the silane compound (B) to dehydration condensation in the presence of water and a dehydration condensation catalyst, a first step of obtaining a first mixture containing a dehydration condensate is carried out. Then, a dehydration condensate contained in the first mixture, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group, and a monomer (C2) not having the salt structure and having a radically polymerizable unsaturated group are subjected to radical polymerization in the presence of an initiator and an organic solvent soluble in water to obtain a second mixture containing a polysiloxane resin in a second step. In a third step, the second mixture is dispersed or dissolved in water to obtain a third mixture. In a fourth step, the organic solvent generated in the first step and the organic solvent used in the second step contained in the third mixture are removed by devolatilization to obtain an aqueous solution or an aqueous dispersion containing a polysiloxane resin.

Effects of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a production method for obtaining an aqueous solution or an aqueous dispersion containing a high molecular weight polysiloxane-based resin, which is excellent in water resistance and weather resistance when formed into a coating film.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present invention will be described in detail. Unless otherwise specified in this specification, "A~B" representing a numerical range means "A or more and B or less".

[0010] 〔1. Production Method of Aqueous Solution or Aqueous Dispersion Containing Polysiloxane-Based Resin〕 The production method of the aqueous solution or aqueous dispersion containing the polysiloxane-based resin according to an embodiment of the present invention includes the following first step, second step, third step, and fourth step. The first step is a step of obtaining a first mixture containing a dehydration condensate by subjecting a silane compound (A) having a radically polymerizable unsaturated group and a hydrolyzable silyl group and a silane compound (B) represented by the general formula (I) other than the silane compound (A) to dehydration condensation in the presence of water and a dehydration condensation catalyst. The second step is a step of obtaining a second mixture containing a polysiloxane-based resin by subjecting the dehydration condensate contained in the first mixture, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group, and a monomer (C2) not having the salt structure and having a radically polymerizable unsaturated group to radical polymerization in the presence of an initiator and an organic solvent soluble in water. The third step is a step of obtaining a third mixture by dispersing or dissolving the second mixture in water. The fourth step is a step of obtaining an aqueous solution or an aqueous dispersion containing a polysiloxane-based resin by removing the organic solvent generated in the first step and the organic solvent used in the second step contained in the third mixture by devolatilization.

[0011] In the manufacturing method according to an embodiment of the present invention, a polysiloxane-based resin having a graft chain is obtained through a first step and a second step. Since the polysiloxane-based resin has a siloxane bond with high binding energy in the main chain, high weather resistance can be expected when it is used as a resin for paints. Further, since a salt structure composed of an acid and a base is incorporated into the graft chain, a water-soluble polysiloxane-based resin is obtained.

[0012] In order to obtain a coating film having even better water resistance and weather resistance, it is preferable to use a high molecular weight polysiloxane-based resin. However, although emulsion polymerization using an emulsifier is known as a method for synthesizing a water-soluble resin, when polymerizing using a polysiloxane macromer having high hydrophobicity and a large molecular weight, it is difficult for the polymerization to proceed within the micelles formed by the emulsifier, so it has been difficult to synthesize a water-soluble resin. This is also shown in Comparative Examples 4 and 5 described later.

[0013] Also, even in the prior art such as Patent Document 1, it may be difficult to obtain an aqueous solution or an aqueous dispersion containing a high molecular weight polysiloxane-based resin that is excellent in water resistance and weather resistance when formed into a coating film. For example, as in Comparative Example 1 described later, even if a high molecular weight polysiloxane-based resin can be synthesized, it may not be soluble or dispersible in water. Further, when the amount of the monomer having a salt structure is increased as in Comparative Example 2 described later, or the molecular weight of the obtained polysiloxane-based resin is decreased by increasing the amount of the initiator as in Comparative Example 3 described later, the polysiloxane-based resin can be dissolved or dispersed in water. However, the obtained coating film may be inferior in water resistance or weather resistance.

[0014] In the manufacturing method according to an embodiment of the present invention, a high molecular weight polysiloxane-based resin can be synthesized by using an organic solvent soluble in water in the second step. Further, the manufacturing method employs a specific water substitution method in which, in the third step, the polysiloxane-based resin is dispersed or dissolved in water in a state of a mixture containing an organic solvent, and then the organic solvent is removed by devolatilization in the fourth step. As a result, the inventors have found that even a high molecular weight polysiloxane-based resin can be obtained as an aqueous solution or an aqueous dispersion.

[0015] The polysiloxane-based resin obtained by the manufacturing method can be used in a state of being dissolved or dispersed in an aqueous medium that has little adverse effect on the human body and the environment. Therefore, for example, it can contribute to the achievement of sustainable development goals (SDGs) such as Goal 12, "Ensure sustainable consumption and production patterns."

[0016] <First step> The first step is a step of obtaining a first mixture containing a dehydration condensate by subjecting a silane compound (A) having a radically polymerizable unsaturated group and a hydrolyzable silyl group and a silane compound (B) represented by the general formula (I) other than the silane compound (A) to dehydration condensation in the presence of water and a dehydration condensation catalyst. In the first step, hydrolysis is also carried out together with dehydration condensation. The first mixture may contain water and an organic solvent generated as a result of the first step in addition to the dehydration condensate of the silane compound (A) and the silane compound (B).

[0017] The dehydration condensate can also be said to be a co-condensate of the silane compound (A) and the silane compound (B). Further, the dehydration condensate can become the main chain of the polysiloxane-based resin obtained in the second step. The dehydration condensate is also called a polysiloxane macromer.

[0018] The silane compound (A) has a radically polymerizable unsaturated group and a hydrolyzable silyl group. In the first step, the silane compound (A) undergoes dehydration condensation with other silane compounds (A) and / or a silane compound (B) to form a polysiloxane macromer. In the second step described later, the radically polymerizable unsaturated group in the silane compound (A) undergoes radical polymerization with the radically polymerizable unsaturated groups derived from the monomer (C1) and the monomer (C2). Thereby, graft chains derived from the monomer (C1) and the monomer (C2) are formed. In the first step, a certain amount of the structural unit derived from the silane compound (A) is contained in the polysiloxane macromer, so that the radical polymerization in the second step proceeds smoothly.

[0019] In one embodiment of the present invention, the silane compound (A) has the following general formula (II): R 3 a R 4 b -Si-(OR 5 ) 4-a―b ···(II) (In the formula, R 3 is a substituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, or an aryl group having a radically polymerizable unsaturated group and optionally having other substituents; R 4 are each independently an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms, or an unsubstituted or substituted aryl group; R 5 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms; a is an integer of 1 to 3; b is an integer of 0 to 2; and a + b is an integer of 1 to 3.) It is a compound having a hydrolyzable silyl group.

[0020] In the general formula (II), in particular, it is preferable that a is 1 and b is 0 or 1. The radically polymerizable unsaturated group is not particularly limited, and examples thereof include a (meth)acryloyl group, a (meth)acrylamide group, and the like.

[0021] R 3Examples of the silane compound having a substituted alkyl group with a radically polymerizable unsaturated group include (meth)acryloxymethyltrimethoxysilane, (meth)acryloxymethylmethyldimethoxysilane, (meth)acryloxymethyldimethylmethoxysilane, (meth)acryloxymethyltriethoxysilane, (meth)acryloxymethylmethyldiethoxysilane, (meth)acryloxymethyldimethylethoxysilane, 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethylmethyldimethoxysilane, 2-(meth)acryloxyethyldimethylmethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 2-(meth)acryloxyethylmethyldiethoxysilane, 2-(meth)acryloxyethyldimethylethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, 4-(meth)acryloxybutyltrimethoxysilane, 4-(meth)acryloxybutylmethyldimethoxysilane, 4-(meth)acryloxybutyldimethylmethoxysilane, 4-(meth)acryloxybutyltriethoxysilane, 4-(meth)acryloxybutylmethyldiethoxysilane, 4-(meth)acryloxybutyldimethylethoxysilane, 5-(meth)acryloxypentyltrimethoxysilane, 5-(meth)acryloxypentylmethyldimethoxysilane, 5-(meth)acryloxypentyldimethylmethoxysilane, 5-(meth)acryloxypentyltriethoxysilane, 5-(meth)acryloxypentylmethyldiethoxysilane, 5-(meth)acryloxypentyldimethylethoxysilane, 6-(meth)acryloxyhexyltrimethoxysilane, 6-(meth)acryloxyhexylmethyldimethoxysilane, 6-(meth)acryloxyhexyldimethylmethoxysilane, 6-(meth)acryloxyhexyltriethoxysilane, 6-(meth)acryloxyhexylmethyldiethoxysilane,Examples include 6-(meth)acryloxyhexyl dimethyl ethoxysilane, etc.

[0022] R 3 Examples of the silane compound in which R is an alkenyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, etc. The alkenyl group is also included in the radically polymerizable unsaturated group.

[0023] R 3 Examples of the silane compound in which R is an aryl group having a radically polymerizable unsaturated group and optionally having other substituents include p-styryltrimethoxysilane, p-styrylmethyldimethoxysilane, p-styryldimethylmethoxysilane, p-styryltriethoxysilane, p-styrylmethyldiethoxysilane, p-styryldimethylethoxysilane, etc.

[0024] Among these, from the viewpoints of high reactivity and versatility, R 3 is preferably an alkyl group substituted with a (meth)acryloyl group.

[0025] R 4 Examples of the alkyl group in R include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, cyclohexyl group, cyclohexylmethyl group, cyclohexylethyl group, heptyl group, isoheptyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, etc. Examples of the aryl group in R 4 include phenyl group, naphthyl group, benzyl group, etc. When a is 1 and b is 1, R 4 is preferably a methyl group.

[0026] R 5Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, and the like. From the viewpoint of facilitating the condensation of the silane compound (A) and the silane compound (B), R 5 The alkyl group preferably has 1 to 3 carbon atoms, and most preferably a methyl group having 1 carbon atom.

[0027] The amount of the silane compound (A) is preferably 1% by weight or more, more preferably 2% by weight or more, based on 100% by weight of the total amount of the polysiloxane resin. When the amount of the silane compound (A) is 1% by weight or more based on 100% by weight of the total amount of the polysiloxane resin, sufficient graft polymerization can occur directly or indirectly with the monomer (C1) and the monomer (C2). As a result, a polysiloxane resin that can be stably dispersed or dissolved (aqueous) in an aqueous medium can be obtained. The upper limit of the amount of the silane compound (A) is not particularly limited as long as the effects of the present invention are achieved, but is preferably 10% by weight or less, more preferably 8% by weight or less.

[0028] The silane compound (B) is a compound having a hydrolyzable silyl group represented by the general formula (I): R 1 n -Si-(OR 2 ) 4-n ···(I) (In the formula, R 1 are each independently a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or an unsubstituted or substituted aryl group, R 2 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 0 to 3.) The silane compound (B) does not have a radically polymerizable unsaturated group.

[0029] In the first step, the silane compound (B) forms a polysiloxane macromer by dehydration condensation with the silane compound (A) and / or between the silane compounds (B). The silane compound (B) is a main component constituting the polysiloxane chain as the main chain.

[0030] R 1 Examples of the alkyl group in R include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, cyclohexyl group, cyclohexylmethyl group, cyclohexylethyl group, heptyl group, isoheptyl group, n-octyl group, isooctyl group, 2-ethylhexyl group and the like. R 1 Examples of the aryl group in R include, for example, phenyl group, naphthyl group, benzyl group and the like.

[0031] R 2 Examples of the alkyl group in R include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, nonyl group, decyl group and the like.

[0032] Specific compounds represented by the general formula (I) include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltriisopropoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, trimethylmonomethoxysilane, triphenylmonomethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-mercaptopyrpropyltrimethoxysilane, and the like.

[0033] The silane compound (B) preferably has a trialkoxysilyl group. That is, the silane compound (B) is preferably a trialkoxysilane compound in which n is 1. When n is 1, three crosslinkable hydrolyzable groups are formed, and a polymer with a network structure can be formed. Specific examples of the compound with n = 1 include, from the viewpoint of availability, preferably compounds such as methyltrimethoxysilane and phenyltrimethoxysilane.

[0034] From the viewpoint of facilitating the condensation of the silane compound (B) and the silane compound (A), the 2 alkyl group of R preferably has 1 to 3 carbon atoms, and most preferably 1 carbon atom.

[0035] The amount of the silane compound (B) is preferably 10% by weight or more, more preferably 20% by weight or more, and still more preferably 40% by weight or more based on 100% by weight of the total amount of the polysiloxane resin. When the amount of the silane compound (B) is 10% by weight or more based on 100% by weight of the total amount of the polysiloxane resin, the polysiloxane resin exhibits effects such as excellent weather resistance, toughness, and tackiness. The upper limit of the amount of the silane compound (B) is not particularly limited as long as the effects of the present invention are achieved, but for example, it is 90% by weight or less.

[0036] The dehydration condensation catalyst is a catalyst that promotes dehydration condensation in the first step. Examples of the dehydration condensation catalyst include neutral catalysts, acidic catalysts, and basic catalysts. From the viewpoint of ease of use, a neutral catalyst or an acidic catalyst is preferred.

[0037] Examples of the neutral catalyst include neutral salts. By using a neutral salt as a catalyst, a polysiloxane macromer with an appropriate degree of condensation can be obtained, and as a result, a solution or dispersion in which water is the medium and contains a polysiloxane resin excellent in storage stability can be obtained.

[0038] In addition, in the first step, using a neutral salt as a catalyst also has the following advantages. · A polysiloxane resin can be obtained without deactivating the organic substituent before and after hydrolysis and dehydration condensation and during storage. · Since the neutral salt itself does not corrode the production container and the storage container, it can be used without being restricted by the material of the production equipment and the storage equipment. · Complicated processes such as the removal process and the neutralization process of the acid or base required when using an acidic catalyst or a basic catalyst can be omitted.

[0039] As used herein, the "neutral salt" means a normal salt composed of an acid and a base. The neutral salt is not particularly limited, but is preferably a salt composed of a combination of a cation selected from the group consisting of Group I element ions, Group II element ions, tetraalkylammonium ions, and guanidium (guanidinium) ions, and an anion selected from the group consisting of Group XVII element ions excluding fluoride ions, sulfate ions, nitrate ions, and perchlorate ions.

[0040] The neutral salt is not particularly limited. For example, lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, francium chloride, beryllium chloride, magnesium chloride, calcium chloride, strontium chloride, barium chloride, radium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, tetrapentylammonium chloride, tetrahexylammonium chloride, guanidinium chloride; lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, francium bromide, beryllium bromide, magnesium bromide, calcium bromide, strontium bromide, barium bromide, radium bromide, tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, guanidinium bromide; lithium iodide, sodium iodide, potassium iodide, rubidium iodide, cesium iodide, francium iodide, beryllium iodide, magnesium iodide, calcium iodide, strontium iodide, barium iodide, radium iodide, tetramethylammonium iodide, tetraethylammonium iodide, tetrapropylammonium iodide, tetrabutylammonium iodide, tetrapentylammonium iodide, tetrahexylammonium iodide, guanidinium iodide; lithium sulfate, sodium sulfate, potassium sulfate, rubidium sulfate, cesium sulfate, francium sulfate, beryllium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, radium sulfate, tetramethylammonium sulfate, tetraethylammonium sulfate, tetrapropylammonium sulfate, tetrabutylammonium sulfate, tetrapentylammonium sulfate, tetrahexylammonium sulfate, guanidinium sulfate;Lithium nitrate, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, francium nitrate, beryllium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, radium nitrate, tetramethylammonium nitrate, tetraethylammonium nitrate, tetrapropylammonium nitrate, tetrabutylammonium nitrate, tetraamylammonium nitrate, tetrahexylammonium nitrate, guanidinium nitrate; lithium perchlorate, sodium perchlorate, potassium perchlorate, rubidium perchlorate, cesium perchlorate, francium perchlorate, beryllium perchlorate, magnesium perchlorate, calcium perchlorate, strontium perchlorate, barium perchlorate, radium perchlorate, tetramethylammonium perchlorate, tetraethylammonium perchlorate, tetrapropylammonium perchlorate, tetrabutylammonium perchlorate, tetraamylammonium perchlorate, tetrahexylammonium perchlorate, guanidinium perchlorate, etc. can be mentioned.;

[0041] Among these neutral salts, from the viewpoint of using them as catalysts, as anions, Group XVII element ions are more preferable because of their high nucleophilicity, and chloride ions, bromide ions, and iodide ions are even more preferable.

[0042] Furthermore, considering availability and safety during handling, as neutral salts, lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, magnesium bromide, calcium bromide, strontium bromide, lithium iodide, sodium iodide, potassium iodide, rubidium iodide, cesium iodide, magnesium iodide, calcium iodide, strontium iodide, tetrabutylammonium chloride, tetrabutylammonium bromide, and tetrabutylammonium iodide are particularly preferable.

[0043] As the acidic catalyst, an organic acid is preferable from the viewpoint of compatibility with the silane compound, and a phosphate ester or a carboxylic acid can be preferably used. Examples of the organic acid include ethyl acid phosphate, butyl acid phosphate, dibutyl pyrophosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, isotridecyl acid phosphate, dibutyl phosphate, bis(2-ethylhexyl) phosphate, formic acid, acetic acid, butyric acid, isobutyric acid, and the like.

[0044] As the basic catalyst, an organic base is preferable from the viewpoint of compatibility with the silane compound and the diluting solvent, and an amine compound can be preferably used. Examples of the organic base include triethylamine, diazabicycloundecene, 1,4-diazabicyclo[2.2.2]octane, and the like.

[0045] These dehydration condensation catalysts can be used alone or in combination of two or more.

[0046] The amount of the dehydration condensation catalyst is preferably 0.1 ppm to 50000 ppm, more preferably 1 ppm to 10000 ppm, still more preferably 5 ppm to 1000 ppm, and particularly preferably 10 ppm to 500 ppm, based on the total amount of the silane compound (A) and the silane compound (B). When the amount of the dehydration condensation catalyst is 0.1 ppm or more, it acts appropriately as a catalyst. Further, when the amount of the dehydration condensation catalyst is 50000 ppm or less, effects such as suppressing the rapid progress of the reaction and suppressing the decrease in water resistance due to the residual salt are exhibited.

[0047] In the first step, water is further used. This water is also referred to as "condensed water". The amount of condensed water in the first step is preferably 0.3 to 1.8 equivalents, more preferably 0.35 to 1.7 equivalents, even more preferably 0.4 to 1.6 equivalents, and particularly preferably 0.5 to 1.5 equivalents, based on the hydrolyzable groups of the silane compound (A) and the silane compound (B). When the amount of condensed water is 0.3 to 1.8 equivalents, the hydrolysis and dehydration condensation of the silane compound in the first step can be controlled, and the amount (degree of condensation) of the OH groups of the polysiloxane macromer can be adjusted. If the amount of condensed water is 0.3 or more, it can prevent the degree of condensation from becoming excessively low and suppress the progress of condensation and gelation over time. Also, if the amount of condensed water is 1.8 or less, it can prevent the degree of condensation from becoming excessively high and suppress the progress of gelation during synthesis.

[0048] In the first step, as a result of dehydration condensation and hydrolysis, an organic solvent is generated. Examples of the organic solvent generated in the first step include methanol, ethanol, 2-propanol, etc.

[0049] <The second step> The second step is a step of obtaining a second mixture containing a polysiloxane-based resin by radical polymerization of the dehydration condensate contained in the first mixture, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group, and a monomer (C2) not having the salt structure and having a radically polymerizable unsaturated group, in the presence of an initiator and an organic solvent soluble in water. In the second step, water may optionally be present. The second step can also be said to be a step of performing radical polymerization using the first mixture, the monomer (C1), and the monomer (C2). The second mixture may contain water, and the organic solvent generated in the first step and the organic solvent used in the second step, in addition to the polysiloxane-based resin.

[0050] In this specification, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group is also referred to as monomer (C1), and a monomer (C2) having no such salt structure and having a radically polymerizable unsaturated group is also referred to as monomer (C2). Monomer (C1) and monomer (C2) are also collectively referred to as monomer (C).

[0051] Monomer (C) is a monomer having a radically polymerizable unsaturated group and no hydrolyzable silyl group. In the second step, the radically polymerizable unsaturated group in monomer (C) undergoes radical polymerization with the radically polymerizable unsaturated group derived from the silane compound (A) to form a graft chain derived from monomer (C) with respect to the polysiloxane main chain.

[0052] The radically polymerizable unsaturated group in monomer (C) is not particularly limited as long as it can contribute to radical polymerization with the silane compound (A) or the like. Examples of the radically polymerizable unsaturated group in monomer (C) include (meth)acryloyl group, (meth)acrylamide group, vinyl group, and the like.

[0053] The amount of monomer (C) is preferably 10% by weight or more, more preferably 15% by weight or more, and still more preferably 20% by weight or more based on 100% by weight of the total amount of the polysiloxane resin. When the amount of monomer (C) is 10% by weight or more based on 100% by weight of the total amount of the polysiloxane resin, a coating film that is difficult to crack can be obtained. The upper limit of the amount of monomer (C) is not particularly limited as long as the effects of the present invention are achieved, but is preferably 80% by weight or less, more preferably 60% by weight or less, and still more preferably 50% by weight or less.

[0054] Monomer (C1) is a monomer having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group. By using monomer (C1), a polysiloxane resin that is easily dissolved or dispersed in water can be obtained.

[0055] Examples of the monomer (C1) include sodium sulfoethyl methacrylate, sodium acrylamide-t-butylsulfonic acid, sodium 2-(methacryloyloxy)ethanesulfonate, sodium 2-(methacryloyloxy)polyalkylene oxide sulfonate, sodium acrylamide-t-butylsulfonic acid, potassium 2-(methacryloyloxy)ethanesulfonate, potassium 2-(methacryloyloxy)polyalkylene oxide sulfonate, potassium acrylamide-t-butylsulfonic acid, calcium 2-(methacryloyloxy)ethanesulfonate, calcium 2-(methacryloyloxy)polyalkylene oxide sulfonate, calcium acrylamide-t-butylsulfonic acid, ammonium sulfoethyl methacrylate, ammonium acrylamide-t-butylsulfonic acid, ammonium 2-(methacryloyloxy)ethanesulfonate, ammonium 2-(methacryloyloxy)polyalkylene oxide sulfonate, ammonium acrylamide-t-butylsulfonic acid, sodium acrylate, potassium acrylate, calcium acrylate, ammonium acrylate, sodium methacrylate, potassium methacrylate, calcium methacrylate, ammonium methacrylate, and the like.

[0056] In addition, the monomer (C1) can be obtained as a commercially available product. Such commercially available products include, for example, "Antox MS-2N-D" manufactured by Nippon Emulsion Co., Ltd., "ATBS-Na" manufactured by Toagosei Co., Ltd., "Eleminol RS-3000" manufactured by Sanyo Chemical Industries, Ltd., "Sodium acrylate" and "Potassium acrylate" manufactured by Asada Chemical Industry Co., Ltd., ADEKA Corporation's Adeka Liasop SR-05, SR-10, SR-20, SR-1025, SR-2025, SR-3025, SR-10S, NE-10, NE-20, NE-30, NE-40, SE-10, SE-20, ER-10, ER-20, ER-30, ER-40, Antox-MS-60, RMA-1120, RMA-564, RMA-568, RMA-506, MA-30, MA-50, MA-100, MA-150, MPG130-MA, MPG-130MA, RMA-150M, RMA-300M, RMA-450M, RA-1020, RA-1820 manufactured by Nippon Emulsion Co., Ltd., Aqualon KH-05, KH-10, RN-20, RN-30, RN-50, RN-2025, HS-10, HS-20, HS-1025, BC05, BC10, BC0515, BC1025 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Eleminol JS-2, JS-20, RS-30 manufactured by Sanyo Chemical Industries, Ltd., Latemul S-180, S-180A, PD-104, PD-420, PD-430 manufactured by Kao Corporation, Brenmer PE-90, PE-200, PE-350, AE-90, AE-200, AE-350, PP-500, PP-800, PP-1000, AP-400, AP-550, AP-800, 700PEP-350B, 10PEP-550B, 55PET-400, 30PET-800, 55PET-800, 30PPT-800, 50PPT-800, 70PPT-800, PME-100, PME-200, PME-400, PME-1000, PME-4000, AME-400, 50POEP-800B, 50AOEP-800B, AEP, AET, APT, PLE, ALE, PSE, ASE, PKE, AKE, PNE, ANE, PNP, ANP, PNEP-600, Light Ester 130MA, 041MA, MTG, Light Acrylate EC-A, MTG-A, 130A, DPM-A, P-200A, NP-4EA, NP-8EA, EHDG-A manufactured by Kyoeisha Chemical Co., Ltd.Examples include NK-ESTER M-20G, M-40G, M-90G, M-230G, AMP-10G, AMP-20G, AMP-60G, AM-90G, LA, etc. manufactured by Shin-Nakamura Chemical Co., Ltd.

[0057] The amount of the monomer (C1) is preferably 1% by weight or more, more preferably 5% by weight or more, based on 100% by weight of the total amount of the polysiloxane resin. When the amount of the monomer (C1) is 1% by weight or more, it is easy to uniformly disperse or solubilize the polysiloxane resin in water. The upper limit of the amount of the monomer (C1) is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 30% by weight or less, more preferably 20% by weight or less.

[0058] These monomers (C1) can be used alone or in combination of two or more.

[0059] The monomer (C2) is not particularly limited as long as it is a monomer having no salt structure, having a radically polymerizable unsaturated group, and not having a hydrolyzable silyl group, unlike the monomer (C1). Examples of the monomer (C2) include (meth)acrylic acid alkyl esters and monomers other than (meth)acrylic acid alkyl esters as shown below.

[0060] In one embodiment of the present invention, the (meth)acrylic acid alkyl ester is a (meth)acrylic acid ester having an alkyl group with 1 to 18 carbon atoms, and can be a (meth)acrylic acid ester that does not contain functional groups such as a hydroxyl group and an epoxy group. The alkyl group in the (meth)acrylic acid alkyl ester may be linear, branched, or a cycloalkyl group that is cyclic. Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, and the like.

[0061] Examples of monomers other than the (meth)acrylic acid alkyl ester include nitrile group-containing radically polymerizable monomers such as (meth)acrylonitrile; epoxy group-containing radically polymerizable monomers such as glycidyl (meth)acrylate; 2-hydroxypropyl (meth)acrylate; hydrophilic radically polymerizable monomers such as radically polymerizable monomers having a polyoxyalkylene chain; monomers having two or more polymerizable unsaturated bonds such as polyethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, allyl (meth)acrylate; fluorine-containing radically polymerizable monomers such as trifluoro(meth)acrylate, pentafluoro(meth)acrylate, perfluorocyclohexyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl methacrylate, β-(perfluorooctyl)ethyl (meth)acrylate, and the like.

[0062] In the second step, the amount of monomer (C1) in the total amount of 100% by weight of monomer (C1) and monomer (C2) is preferably 5% by weight or more, more preferably 10% by weight or more. When the amount of monomer (C1) is 5% by weight or more, it is easy to uniformly disperse or solubilize the polysiloxane resin in water. From the viewpoint of obtaining a coating film having more excellent water resistance and weather resistance, the upper limit of the amount of monomer (C1) is preferably 50% by weight or less, more preferably 30% by weight or less, and still more preferably 25% by weight or less. In one embodiment of the present invention, since a second mixture containing an organic solvent soluble in water is used in the third step, even if the amount of monomer (C1) incorporated into the polysiloxane resin is relatively small, the polysiloxane resin can be dissolved or dispersed in water.

[0063] In the second step, in addition to the monomer (C), an initiator is used. The initiator is a radical polymerization initiator. The initiator is not particularly limited as long as it is a substance capable of initiating a radical polymerization reaction between the radically polymerizable unsaturated group derived from the silane compound (A) and the monomer (C).

[0064] Examples of the initiator include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), tert-butyl peroxy pivalate, tert-butyl peroxy benzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, diisopropyl peroxycarbonate, and the like.

[0065] The amount of the initiator is preferably 0.01 to 10% by weight, more preferably 0.05 to 7% by weight, and still more preferably 0.1 to 5% by weight based on 100% by weight of the total amount of the polysiloxane resin. When the amount of the initiator is 0.01% by weight or more, the polymerization easily proceeds appropriately. When the amount of the initiator is 10% by weight or less, it is easy to obtain a polymer having an appropriate molecular weight.

[0066] In the second step, an organic solvent soluble in water is used. By using an organic solvent soluble in water, the radical polymerization of the highly hydrophobic and high molecular weight polysiloxane macromer obtained in the first step and the monomer (C) can proceed favorably. Examples of the organic solvent soluble in water include methanol, ethanol, 2-propanol, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, and the like. Among these, considering the possibility of devolatilization in the fourth step or volatilization during the formation of the coating film, alcohol solvents such as methanol, ethanol, and 2-propanol are particularly preferred.

[0067] In the second step, in addition to the monomer (C), the initiator, water, and the organic solvent soluble in water, any additive may be added within the range in which the effects of the present invention are exhibited. Such additives can be appropriately selected by those skilled in the art.

[0068] The polysiloxane resin obtained in the second step is one in which a graft chain is formed with respect to the dehydration condensate (cocondensate) obtained in the first step, and can also be referred to as a graft cocondensate. Also, it can be said that the polysiloxane resin has a side chain derived from monomer (C) with the polysiloxane macromer obtained in the first step as the main chain.

[0069] The weight average molecular weight of the polysiloxane resin obtained in the second step is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, and even more preferably 60,000 to 100,000. If the weight average molecular weight of the polysiloxane resin is 40,000 or more, a coating film excellent in water resistance and weather resistance can be obtained. In this specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC). The weight average molecular weight of the polysiloxane resin can be controlled by adjusting the amount of the initiator.

[0070] The second step preferably includes a step of intermittently adding monomer (C1), monomer (C2), an initiator, and a water-soluble organic solvent to the first mixture and performing radical polymerization. Also, water may be optionally added in this step. By intermittently adding the reaction materials in this way, the radical polymerization reaction can be stably carried out.

[0071] <The third step> The third step is a step of obtaining a third mixture by dispersing or dissolving the second mixture in water. In the third step, it can be said that the second mixture is diluted with water, or it can be said that the main medium contained in the second mixture is replaced with water.

[0072] The third mixture may contain the components contained in the second mixture. It can also be said that the third mixture is a mixture in a state where the organic solvent generated in the first step and the organic solvent used in the second step are contained in an aqueous dispersion or aqueous solution of the polysiloxane resin. It can also be said that the proportion of water in the third mixture is larger than that in the second mixture.

[0073] <Step 4> Step 4 is a step of obtaining an aqueous solution or an aqueous dispersion containing a polysiloxane resin by removing, by devolatilization, the organic solvent generated in the first step and the organic solvent used in the second step, which are contained in the third mixture. An aqueous solution or an aqueous dispersion containing a polysiloxane resin is, in other words, a solution or a dispersion containing a polysiloxane resin and having water as a medium.

[0074] When the resin solid content concentration of the aqueous solution containing a polysiloxane resin is 20% and the proportion of water in the entire medium is 90% by weight or more, it can be a liquid with a transparent appearance, more specifically, a liquid having a haze value of 20.0 or less at 1 atm and 25°C. Further, when the resin solid content concentration of the aqueous dispersion containing a polysiloxane resin is 20% and the proportion of water in the entire medium is 90% by weight or more, it can be a liquid with a cloudy appearance, more specifically, a liquid having a haze value higher than 20.0 at 1 atm and 25°C. The haze value is measured using COH400 manufactured by Nippon Denshoku Industries Co., Ltd. with pure water as a standard solution.

[0075] From the viewpoint of preventing gelation of the polysiloxane resin, the devolatilization temperature in Step 4 is preferably 60°C or lower, more preferably 50°C or lower. Further, from the viewpoint of devolatilization efficiency, the devolatilization temperature is preferably 30°C or higher, more preferably 40°C or higher.

[0076] 〔2. Water-based paint〕 The aqueous solution or aqueous dispersion containing a polysiloxane resin obtained by the above production method can be used as a water-based paint. A water-based paint is also called an aqueous paint. The coating film obtained from the water-based paint is excellent in water resistance and weather resistance.

[0077] The aqueous paint may contain additives commonly used in the art. Such additives include, for example, pigments, fillers, plasticizers, film-forming aids, wetting / dispersing agents, thickeners, defoamers, preservatives, antioxidants, anti-settling agents, leveling agents, ultraviolet absorbers, antistatic agents, antifreeze agents, antibacterial agents, fungicides, tackifiers, rust preventives, etc. As the additive, only one kind may be contained, or two or more kinds may be contained. The amounts of these additives can be appropriately set by those skilled in the art according to the purpose of use.

[0078] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0079] One embodiment of the present invention may include the following configuration. <1>A silane compound (A) having a radically polymerizable unsaturated group and a hydrolyzable silyl group, and other than the silane compound (A), the following general formula (I): R 1 n -Si-(OR 2 ) 4-n ···(I) (In the formula, R 1 are each independently an alkyl group having 1 to 10 carbon atoms, or an unsubstituted or substituted aryl group, and R 2is independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 0 to 3. A first step of obtaining a first mixture containing a dehydrated condensate by subjecting a silane compound (B) represented by the formula: to dehydrative condensation in the presence of water and a dehydrative condensation catalyst; a second step of obtaining a second mixture containing a polysiloxane resin by subjecting the dehydrated condensate contained in the first mixture, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group, and a monomer (C2) having no such salt structure and having a radically polymerizable unsaturated group to radical polymerization in the presence of an initiator and an organic solvent soluble in water; a third step of obtaining a third mixture by dispersing or dissolving the second mixture in water; and a fourth step of obtaining an aqueous solution or an aqueous dispersion containing a polysiloxane resin by removing the organic solvent generated in the first step and the organic solvent used in the second step contained in the third mixture by devolatilization. A method for producing an aqueous solution or an aqueous dispersion containing a polysiloxane resin, which comprises the steps of: <2>The production method according to <1>, wherein the weight average molecular weight of the polysiloxane resin obtained in the second step is 40,000 to 200,000. <3>The production method according to <1> or <2>, wherein in the second step, the amount of the monomer (C1) in 100% by weight of the total amount of the monomer (C1) and the monomer (C2) is 5 to 50% by weight. <4>The second step includes a step of intermittently adding the monomer (C1), the monomer (C2), an initiator, and an organic solvent soluble in water to the first mixture and performing radical polymerization. The production method according to any one of <1> to <3>. <5>The production method according to any one of <1> to <4>, wherein in the first step, the silane compound (B) has a trialkoxysilyl group. <6>The production method according to any one of <1> to <5>, wherein the organic solvent soluble in water is an alcohol-based solvent. <7>The production method according to any one of <1> to <6>, wherein the devolatilization temperature in the fourth step is 60°C or lower.

Examples

[0080] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[0081] 〔Materials〕 In the examples and comparative examples, the following materials were used.

[0082] (Silane compound (A)) γ-Methacryloxypropyltrimethoxysilane (3-(trimethoxysilyl)propyl methacrylate, abbreviation "TSMA"): "A-174" manufactured by Momentive Performance Materials Japan Co., Ltd. (Silane compound (B)) Methyltrimethoxysilane (abbreviation "M-TMS"): "Z-6033" manufactured by Dow Corning Toray Co., Ltd. Phenyltrimethoxysilane (abbreviation "Ph-TMS"): "Z-6124" manufactured by Dow Corning Toray Co., Ltd. (Monomer (C1)) Ether sulfate type ammonium salt (abbreviation "SR-10"): "Adekaria Soap SR-10" manufactured by ADEKA Corporation Sodium acrylamide-t-butylsulfonate (abbreviation "ATBS-Na"): "ATBS-Na" manufactured by Toagosei Co., Ltd. (Monomer (C2)) Methyl methacrylate (abbreviation "MMA"): Manufactured by Mitsubishi Gas Chemical Company, Inc. Butyl acrylate (abbreviation "BA"): Manufactured by Nippon Shokubai Co., Ltd. (Dehydration condensation catalyst) Dibutyl phosphate (abbreviation "DBP"): Manufactured by Johoku Chemical Industry Co., Ltd., acid catalyst (Initiator) Radical polymerization initiator: 2,2'-azobis(2,4-dimethylvaleronitrile): "V-65" manufactured by Tokyo Chemical Industry Co., Ltd. Radical polymerization initiator: Potassium persulfate (abbreviation "KPS"): Manufactured by Sigma-Aldrich 〔Measurement and evaluation methods〕 In the examples and comparative examples, the measurement and evaluation were carried out by the following methods.

[0083] <Weight average molecular weight> The weight average molecular weight of the polysiloxane resin before dilution with water was measured using a high-speed GPC apparatus HLC-8320GPC manufactured by Tosoh Corporation.

[0084] <Water resistance> (Preparation of coating film) An aqueous solution or aqueous dispersion containing a polysiloxane resin was applied to glass using an applicator with a width of 6 mils, and cured at 50°C for 18 hours to prepare a specimen having a coating film (cured product).

[0085] (Evaluation method) The specimen was immersed in pure water at 50°C for 24 hours, and the appearance immediately after removal was visually evaluated. When there was no whitening, cracking, wrinkling, or water swelling, it was judged as "good", and when whitening, cracking, wrinkling, or water swelling occurred, it was judged as "bad".

[0086] <Weather resistance> (Preparation of coating film) Using the polysiloxane resins of Examples 1 to 6 and Comparative Examples 2, 3, and 5, a cured film was prepared from an aqueous paint (white base paint) formulated with the components according to the formulation shown in Table 2 (Examples 7 to 12, Comparative Examples 6 to 8). Briefly, an aqueous paint was obtained by adding the mill base obtained by formulating the components shown in the "Mill Base" of Table 2 to the components shown in the "Cutback" of Table 2. An aluminum plate (50 mm × 150 mm) coated with Hypone Fine Primer II (manufactured by Nippon Paint) as a primer was coated with the aqueous paint on the primer layer surface. Coating was performed using an air spray so that the dry film thickness (the film thickness of the cured film after drying) was about 40 μm. The obtained coating film was dried at 23°C and 50% RH for 4 hours (first coating). Further, on the dry film obtained by the first coating, the aqueous paint was again applied using an air spray so that the dry film thickness was about 40 μm (that is, so that the film thickness of the cured film after drying on the primer layer was a total of 80 μm). The obtained coating film was dried at 23°C and 50% RH for 1 week (second coating). By these operations, a laminate in which a primer layer and a cured film were laminated in this order on an aluminum plate as a base material was obtained. Using the obtained laminate as a test piece, the weather resistance of the cured film was measured.

[0087] (Evaluation Method) Using a metal halide lamp type tester (manufactured by Daipla Wintersteiger Co., Ltd., model KU-R5CI-A), an accelerated weathering test of the test piece was carried out. The 60° gloss value of the cured film was measured before and after about 800 hours of the accelerated weathering test, and the gloss retention rate was calculated.

[0088] As the 60° gloss value, the gloss value at an incident angle of 60° of the test piece was measured using a gloss meter Multi-Gloss268 manufactured by Minolta Co., Ltd.

[0089] The higher the gloss value, the better the appearance. The higher the gloss retention rate, the better the weather resistance. In the accelerated weathering test, irradiation, shower, dew condensation, and shower were performed in this order in one cycle, and this cycle was repeated for 800 hours. The test conditions of the accelerated weathering test were as follows. Irradiation: Illuminance 85 mW / cm 2 , Temperature 63 °C, Relative humidity 50%, 6 hours Condensation: Temperature 30 °C, Relative humidity 98%, 2 hours Shower: 30 seconds before and after condensation.

[0090] [Example 1] (Preparation of co - condensate (main chain)) Into a reactor equipped with a stirrer, a thermometer and a reflux condenser, 4.0 parts by weight of TSMA, 42.9 parts by weight of M - TMS, 36.3 parts by weight of Ph - TMS, 21.8 parts by weight of pure water, and 0.025 parts by weight of DBP were charged, and the reaction was carried out with stirring at a reaction temperature of 70 °C for 3 hours (the first step). As a result, a first mixture containing a co - condensate (dehydration condensate) was obtained.

[0091] (Preparation of graft co - condensate (polymerization of side chain)) Into a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas inlet tube and a dropping funnel, 10 parts by weight of pure water and 15 parts by weight of 2 - propanol were charged, and the temperature was raised to 75 °C while introducing nitrogen gas. Then, a mixed solution of the first mixture, 3.0 parts by weight of ATBS - Na, 6.0 parts by weight of SR - 10, 20.5 parts by weight of MMA, 20.5 parts by weight of BA, 0.5 parts by weight of 2,2 - azobis(2,4 - dimethylvaleronitrile), 10 parts by weight of pure water, and 10 parts by weight of 2 - propanol was added dropwise from the dropping funnel at a constant rate over 5 hours. Next, a mixed solution of 0.05 parts by weight of 2,2 - azobis(2,4 - dimethylvaleronitrile) and 5 parts by weight of 2 - propanol was added dropwise at a constant rate over 1 hour. Then, stirring was continued at 75 °C for 2 hours (the second step). Subsequently, 120 parts by weight of pure water was added, and stirring was carried out at 40 °C for 1 hour (the third step). Subsequently, devolatilization was carried out at a gauge pressure of 160 hPa and a temperature of 60 °C using a rotary evaporator until the non - volatile component reached 50% (the fourth step). After cooling to room temperature, an aqueous solution containing a graft co - condensate (polysiloxane - based resin) was obtained.

[0092] [Examples 2 - 6] An aqueous solution containing a polysiloxane resin was obtained in the same manner as in Example 1, except that the charged amounts of the respective components were changed as described in Table 1.

[0093] [Comparative Example 1] (Preparation of co-condensate (main chain)) Into a reactor equipped with a stirrer, a thermometer, and a reflux condenser, 4.0 parts by weight of TSMA, 42.9 parts by weight of M-TMS, 36.3 parts by weight of Ph-TMS, 21.8 parts by weight of pure water, and 0.025 parts by weight of DBP were charged, and the reaction was carried out with stirring at a reaction temperature of 70 °C for 3 hours. Thereby, a first mixture containing a co-condensate (dehydration condensate) was obtained.

[0094] (Preparation of graft co-condensate (polymerization of side chain)) Into a reactor equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introduction tube, and a dropping funnel, 10 parts by weight of pure water and 15 parts by weight of 2-propanol were charged, and the temperature was raised to 75 °C while introducing nitrogen gas. Then, a mixed solution of the first mixture, 3.0 parts by weight of ATBS-Na, 6.0 parts by weight of SR-10, 20.5 parts by weight of MMA, 20.5 parts by weight of BA, 0.5 parts by weight of 2,2-azobis(2,4-dimethylvaleronitrile), 10 parts by weight of pure water, and 10 parts by weight of 2-propanol was added dropwise at a constant rate from the dropping funnel over 5 hours. Next, a mixed solution of 0.05 parts by weight of 2,2-azobis(2,4-dimethylvaleronitrile) and 5 parts by weight of 2-propanol was added dropwise at a constant rate over 1 hour. Then, stirring was continued at 75 °C for 2 hours, and then devolatilization was carried out at a gauge pressure of 160 hPa and a temperature of 60 °C using a rotary evaporator until the non-volatile component became 90% or more. Subsequently, dilution was carried out with water so that the non-volatile component became 50%. After cooling to room temperature, a graft co-condensate (polysiloxane resin) was obtained. However, the polysiloxane resin and water were separated, and an aqueous solution or an aqueous dispersion containing the polysiloxane resin could not be obtained.

[0095] [Comparative Examples 2 and 3] An aqueous solution containing a polysiloxane resin was obtained in the same manner as in Comparative Example 1, except that the charged amounts of the respective components were changed as described in Table 1.

[0096] [Comparative Example 4] Into a reactor equipped with a stirrer, a thermometer, and a reflux condenser, 4.0 parts by weight of TSMA, 42.9 parts by weight of M-TMS, 36.3 parts by weight of Ph-TMS, 15.4 parts by weight of pure water, and 0.017 parts by weight of DBP were charged, and the reaction was carried out with stirring at a reaction temperature of 105°C for 3 hours to obtain a first mixture containing a co-condensate (dehydration condensate). The obtained first mixture was subjected to devolatilization at a gauge pressure of 160 hPa and a temperature of 60°C using a rotary evaporator until the non-volatile component became 90% or more.

[0097] Into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen gas introduction tube, and a dropping funnel, 100 parts by weight of pure water, 0.7 parts by weight of SR-10, and 1.0 part by weight of a 5% aqueous sodium hydrogen carbonate solution were charged, and the temperature was raised to 80°C while introducing nitrogen gas.

[0098] After the temperature was raised, 0.5 part by weight of KPS was added, and then a mixture of the first mixture after the above devolatilization, 6.0 parts by weight of SR-10, 22.0 parts by weight of MMA, and 22.0 parts by weight of BA was dropped at a constant rate over 180 minutes using the dropping funnel to carry out polymerization.

[0099] After the dropping was completed, post-polymerization was carried out for 120 minutes, but aggregates were generated, and an aqueous solution or an aqueous dispersion containing a polysiloxane resin could not be obtained.

[0100] [Comparative Example 5] A resin emulsion (aqueous dispersion containing a polysiloxane resin) was obtained in the same manner as in Comparative Example 4, except that the charged amounts of the respective components were changed as described in Table 1.

[0101] [Evaluation Results] The charged amounts and evaluation results of the Examples and Comparative Examples are shown in Table 1. "Manufacturing process" in Table 1 indicates the following. A: It was diluted with water and then the organic solvent was devolatilized. That is, the first step, the second step, the third step, and the fourth step were carried out in sequence. B: The organic solvent was devolatilized and then it was diluted with water. That is, it can also be said that the first step, the second step, the fourth step, and the third step were carried out in this order. C: After synthesizing the macromer, the organic solvent was devolatilized and then emulsion polymerization was carried out.

[0102] Also, regarding "resin synthesis" in Table 1, when a polysiloxane-based resin was obtained, it was evaluated as "acceptable", and when it was not obtained, it was evaluated as "unacceptable". Regarding "water substitution" in Table 1, when an aqueous solution or aqueous dispersion containing a polysiloxane-based resin was obtained by dilution with water, it was evaluated as "acceptable", and when it was not obtained, it was evaluated as "unacceptable".

[0103]

Table 1

[0104]

Table 2

[0105] From Table 1 and Table 2, in Examples 1 to 6 where the fourth step was carried out after the third step, an aqueous solution or aqueous dispersion containing a high molecular weight polysiloxane-based resin could be obtained, and a coating film excellent in water resistance and weather resistance (Examples 7 to 12) could also be obtained.

[0106] In contrast, in Comparative Example 1 in which the same amount of charge as in Example 1 was used but the third step was carried out after the fourth step, the polysiloxane-based resin and water were separated, and an aqueous solution or aqueous dispersion containing the polysiloxane-based resin could not be obtained. Further, in Comparative Example 2 in which the amount of the monomer (C1) charged was increased as compared with Comparative Example 1, although an aqueous solution or aqueous dispersion containing the polysiloxane-based resin was obtained, the water resistance and weather resistance of the coating film (Comparative Example 6) were inferior to those of the examples. In Comparative Example 3 in which the amount of the initiator charged was increased as compared with Comparative Example 1, the molecular weight of the polysiloxane-based resin was lower than that of the examples, and the water resistance and weather resistance of the coating film (Comparative Example 7) were inferior.

[0107] In Comparative Example 4 in which emulsion polymerization was attempted, a polysiloxane-based resin could not be obtained. Further, in Comparative Example 5 in which the amount of the initiator charged was increased, although a polysiloxane-based resin was obtained, the water resistance and weather resistance of the coating film (Comparative Example 8) were inferior to those of the examples. [Industrial Applicability]

[0108] One aspect of the present invention can be used in various fields such as aqueous paints and coating agents.

Claims

1. A silane compound (A) having a radically polymerizable unsaturated group and a hydrolyzable silyl group, and other than the silane compound (A), the following general formula (I): R １ ｎ -Si-(OR ２ ) ４－ｎ ...(I) (In the formula, R １ is each independently an alkyl group having 1 to 10 carbon atoms or an unsubstituted or substituted aryl group, and R ２ is each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 0 to 3.) A first step of obtaining a first mixture containing a dehydration condensate by subjecting a silane compound (B) represented by the formula to dehydration condensation in the presence of water and a dehydration condensation catalyst; The dehydrated condensate contained in the first mixture, a monomer (C1) having a salt structure composed of an acid and a base and having a radically polymerizable unsaturated group, and a monomer (C2) not having the salt structure and having a radically polymerizable unsaturated group are radically polymerized in the presence of an initiator and an organic solvent soluble in water to obtain a second mixture containing a polysiloxane resin; a second step; A third step of obtaining a third mixture by dispersing or dissolving the second mixture in water; A fourth step of removing the organic solvent generated in the first step and the organic solvent used in the second step contained in the third mixture by devolatilization to obtain an aqueous solution or an aqueous dispersion containing a polysiloxane resin. A method for producing an aqueous solution or an aqueous dispersion containing a polysiloxane resin.

2. The method according to claim 1, wherein the weight average molecular weight of the polysiloxane resin obtained in the second step is 40,000 to 200,000.

3. The method according to claim 1 or 2, wherein the amount of the monomer (C1) in the total amount of 100% by weight of the monomer (C1) and the monomer (C2) in the second step is 5 to 50% by weight.

4. The method according to claim 1 or 2, wherein the second step includes a step of intermittently adding the monomer (C1), the monomer (C2), an initiator, and an organic solvent soluble in water to the first mixture and performing radical polymerization.

5. The method according to claim 1 or 2, wherein in the first step, the silane compound (B) has a trialkoxysilyl group.

6. The method according to claim 1 or 2, wherein the organic solvent soluble in water is an alcohol-based solvent.

7. The method according to claim 1 or 2, wherein the devolatilization temperature in the fourth step is 60°C or lower.

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