JP2000264968A - Production of polyorganosiloxane-based latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject latex with number-average particle size at a specific value or lower even when using a small amount of an emulsifier by using a specific composition as a mixture of cyclic organosiloxane oligomers each composed of a specific structural unit. SOLUTION: This polyorganosiloxane-based latex with a number-average particle size of 0.008-0.1 μm is obtained by emulsion polymerization pref. in an acidic state of <=pH 3 under heating to >=60 deg.C of a mixture of 0-10 wt.% of the trimer, 40-95 wt.% of the tetramer, 5-40 wt.% of the pentamer, and 0-10 wt.% of the hexamer and higher-order macromer of a cyclic organosiloxane oligomer composed of structural unit of the formula (R1 and R2 are each a 1-10C univalent hydrocarbon such as methyl ethyl or propyl) (pref. a cyclic dimethylsiloxne oligomer). Thereby, the objective latex suitable for use as e.g. an impact resistance improver, slidability-imparting agent, water repellency- imparting agent is afforded even without using a large quantity of emulsifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an impact modifier,
Suitable for use in slidability imparting agents, water repellency imparting agents, processing aids for molding materials, flame retardants and coating materials, etc.
The present invention relates to a method for producing a polyorganosiloxane latex having a number average particle size of 0.1 μm or less.

[0002]

2. Description of the Related Art Polyorganosiloxane-based particles have good properties such as elasticity, water resistance, thermal stability, weather resistance, flame retardancy and lubricity. It is widely used as a raw material for agents, slidability imparting agents, water repellency imparting agents, molding material processing aids, flame retardants and coating materials. In these applications, some studies have been made to reduce the average particle size of the polyorganosiloxane-based latex to 0.1 μm or less in order to achieve higher performance, but still satisfactory ones have been obtained. Absent.

JP-A-62-141029 discloses that a reaction system comprising water and a polymerization catalyst is provided with an octamethylcyclotetrasiloxane (a cyclic dimethylsiloxane oligomer 4).
), An emulsion consisting of an emulsifier and water,
A method for producing a polyorganosiloxane-based latex having an average particle size of 0.1 μm or less by polymerization is disclosed.

JP-A-5-194740 discloses that a reaction system consisting of water and a polymerization catalyst contains octamethylcyclotetrasiloxane (a tetramer of a cyclic dimethylsiloxane oligomer), a siloxane-based crosslinking agent, and a siloxane-based graft-linking agent. There is disclosed a method for producing a polyorganosiloxane-based latex having an average particle size of 0.1 μm or less by dropping and polymerizing an emulsion comprising a mixture, an emulsifier and water.

[0005]

However, Japanese Patent Application Laid-Open No. 62-141029 and Japanese Patent Application Laid-Open No. 5-1
In any of the methods disclosed in Japanese Patent No. 94740, a large amount of an emulsifier must be used in order to reduce the particle diameter of the polyorganosiloxane-based latex to 0.1 μm or less, and the obtained polyorganosiloxane-based latex is used as a raw material. When the slidability improver and the like are mixed with a thermoplastic resin or the like and molded, a quality problem such as deterioration of the appearance of the molded article caused by the residual emulsifier is caused.

The gist of the present invention is to produce a polyorganosiloxane latex having a number average particle size of 0.1 μm or less with a smaller amount of emulsifier than the conventional method.

[0007]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that when a mixture of a specific composition of a cyclic organosiloxane oligomer composed of a specific structural unit is used, a smaller amount than in the prior art is used. The present inventors have found that a polyorganosiloxane latex having a number average particle size of 0.1 μm or less can be produced with an emulsifier, and have completed the present invention.

That is, the present invention provides a compound represented by the general formula:

[0009]

Embedded image (Wherein R ¹ and R ² represent a methyl group, an ethyl group, a propyl group,
A monovalent hydrocarbon group having 1 to 10 carbon atoms such as a phenyl group, and R ¹ and R ² may be the same or different. Has a number average particle diameter of 0.008 to
A method for producing a 0.1 μm polyorganosiloxane-based latex, wherein a mixture of cyclic organosiloxane oligomers comprises 0 to 10% of trimers (% by weight, the same applies hereinafter), 40 to 95% of tetramers, and 5 ~ 40%, hexamer or more 0 ~ 1
0%, the production method (Claim 1),
The method for producing a polyorganosiloxane-based latex according to claim 1, wherein the mixture of cyclic organosiloxane oligomers is a mixture of cyclic dimethylsiloxane oligomers (claim 2). The method for producing a polyorganosiloxane-based latex according to claim 1 or 2, which is performed by heating (claim 3).
About.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention has the general formula:

[0011]

Embedded image (Wherein R ¹ and R ² represent a methyl group, an ethyl group, a propyl group,
A monovalent hydrocarbon group having 1 to 10 carbon atoms such as a phenyl group, and R ¹ and R ² may be the same or different. Has a number average particle diameter of 0.008 to
A method for producing a 0.1 μm polyorganosiloxane-based latex, wherein a mixture of cyclic organosiloxane oligomers comprises 0 to 10% of trimers, 40 to 95% of tetramers, 5 to 40% of pentamers, and 6-mers. 0-10% (total amount 100
%).

The polyorganosiloxane-based latex obtained according to the present invention has a number average particle diameter of 0.008 to 0.1 μm as determined by light scattering or electron microscopic observation.
And preferably 0.01 to 0.08 μm.

If the number average particle size is too small,
The coating itself tends to be difficult, and when it is too large, for example, when used as a coating material, the smoothness of the coating film surface tends to be poor.

The cyclic organosiloxane oligomer is a component for forming a main skeleton of a polyorganosiloxane chain, and specific examples thereof include a cyclic dimethylsiloxane oligomer, a cyclic diethylsiloxane oligomer, a cyclic methylphenylsiloxane oligomer, a cyclic diphenyl oligomer. And siloxane oligomers. These may be used alone or in combination of two or more.
Of these, cyclic dimethylsiloxane oligomers are particularly preferred from the economical point of view.

For example, the trimer of the cyclic dimethylsiloxane oligomer is hexamethylcyclotrisiloxane, and the tetramer is octamethylcyclotetrasiloxane.
The dimer is commercially available as decamethylcyclopentasiloxane, the hexamer is commercially available as dodecamethylcyclohexasiloxane, and the heptamer is commercially available as tetradecamethylcycloheptasiloxane. The mixture of the cyclic organosiloxane oligomer of the present invention refers to a mixture of such homologs.

In order to achieve the present invention, the mixture of the above-mentioned cyclic organosiloxane oligomer is a copolymer of 0 to 10% trimer,
40 to 95% tetramer, 5 to 40% pentamer, 6 or more hexamer 0
-10% (total amount 100%). In particular, trimers are 1 to 6%, tetramers are 54 to 93%, pentamers are 5 to 30%, and hexamers are 1 to 10% or more in that it is easy to obtain smaller average particle diameters. Is preferred. When the composition of the mixture of cyclic organosiloxane oligomers is analytically confirmed, gas chromatography (for example, "Silicone Handbook" edited by Kunio Ito, published by Nikkan Kogyo Shimbun, 1990, p.785, etc. ) Can be easily confirmed.

The trimer is an optional component, but if the amount is too large, the stability of the system tends to decrease.

If the amount of the tetramer is too small, the cost tends to increase. If the amount is too large, a polyorganosiloxane latex having a number average particle diameter of 0.1 μm or less can be obtained with a smaller amount of emulsifier than in the prior art. The characteristics of the present invention tend to be not obtained.

If the amount of the pentamer is too small, the characteristic of the present invention that a polyorganosiloxane latex having a number average particle size of 0.1 μm or less can be obtained with a small amount of an emulsifier as compared with the prior art tends not to be obtained. Yes, if too many, cost tends to increase.

The hexamer or higher oligomer is an optional component, but if it is too large, the cost tends to increase and the stability of the system tends to decrease.

The upper limit of the oligomer having a hexamer or higher is preferably a 20-mer or, more preferably, a 10-mer. If the oligomer exceeds the 20-mer, the stability of the system during the polymerization is lowered. Tend to.

Emulsion polymerization of a mixture of the aforementioned cyclic organosiloxane oligomers is described, for example, in US Pat.
The method can be carried out by using a known method described in, for example, JP-A No. 20 and JP-A-3294725.

For example, a mixture of the above-mentioned cyclic organosiloxane oligomer can be emulsified and dispersed in water by mechanical shearing in the presence of an emulsifier, and polymerized in an acidic state.
In such a method, preparing emulsion droplets of several μm or more by mechanical shearing can reduce the number average particle diameter of the polyorganosiloxane latex obtained after polymerization to 0.008 to 0.1 μm, preferably 0.01 to 0.1 μm. 0.0
It is preferable because it can be easily controlled in the range of 8 μm.

Further, the number average particle diameter is 0.008 to 0.5.
In order to obtain a polymer having a particle size distribution of 1 μm, preferably 0.01 to 0.08 μm and a narrow particle size distribution, it is preferable to carry out polymerization in multiple stages. For example, 1 to 20% of an emulsion consisting of emulsified droplets of several μm or more obtained by emulsifying a mixture of the above-mentioned cyclic organosiloxane oligomer, water and an emulsifier by mechanical shearing is first subjected to emulsion polymerization in an acidic state. The remaining emulsion is additionally polymerized in the presence of the obtained polyorganosiloxane as a seed. The coefficient of variation (100 × standard deviation / number average particle diameter (%)) of the particle diameter distribution of the polyorganosiloxane-based latex thus obtained tends to be 50% or less. Further, in the multi-stage polymerization, the same procedure is carried out using a vinyl-based polymer obtained by polymerizing a vinyl-based monomer (for example, styrene, butyl acrylate, etc.) by a usual emulsion polymerization method instead of the seed of polyorganosiloxane. Even if multi-stage polymerization is performed, the coefficient of variation (100 × standard deviation / number average particle diameter (%)) of the particle diameter distribution of the obtained vinyl polymer-containing polyorganosiloxane (modified polyorganosiloxane) latex is 50% or less. Tends to be.

The emulsified droplets having a size of several μm or more can be prepared by using a high-speed stirrer such as a homomixer.

The emulsifier used in these methods does not lose its activity as an emulsifier even in an acidic region. Examples of such an emulsifier include alkylbenzenesulfonic acid, sodium alkylbenzenesulfonic acid, alkylsulfonic acid, and alkylsulfonic acid. Examples include sodium sulfonate, sodium (di) alkyl sulfosuccinate, sodium polyoxyethylene nonylphenyl ether sulfonate, and sodium alkyl sulfate. These may be used alone or in combination of two or more.

The acidic state may be determined by adding inorganic acids such as sulfuric acid and hydrochloric acid, alkylbenzenesulfonic acid, alkylsulfonic acid,
An organic acid such as trifluoroacetic acid is added to adjust the pH to 1 to 3.
It is preferred that In particular, alkyl benzene sulfonic acid or alkyl sulfonic acid is preferable because it also acts as an emulsifier.

The reaction temperature during the polymerization is 60 to 120 ° C.
Further, the temperature is preferably from 70 to 100 ° C. from the viewpoint that the polymerization rate is moderate.

Thus, a polyorganosiloxane-based latex is obtained. Under acidic conditions, the Si—O—Si bond forming the polyorganosiloxane skeleton is in an equilibrium state of cleavage and formation, and this equilibrium depends on temperature. Since it changes, it is preferable to neutralize by adding an aqueous alkali solution such as sodium hydroxide, potassium hydroxide or sodium carbonate in order to stabilize the polyorganosiloxane chain. Furthermore, the lower the temperature, the higher the molecular weight or the degree of crosslinking (in the case of using a silane compound having three or more functions described later) more easily at a lower temperature. In order to obtain the polyorganosiloxane latex, the polymerization is carried out at 60 ° C. or higher, then cooled to about room temperature,
It is preferable to neutralize after holding for about 100 hours.

Further, a bifunctional silane compound, a trifunctional or higher silane compound, a silane compound having a vinyl polymerizable group, or the like may be used in combination with the mixture of the cyclic organosiloxane oligomer.

The combination may be carried out, for example, by mixing a mixture of the above-mentioned cyclic organosiloxane oligomers, a bifunctional silane compound, a trifunctional or higher silane compound, and a silane compound having a vinyl polymerizable group, followed by polymerization. For example, during or after polymerization of the mixture of the cyclic organosiloxane oligomers, a bifunctional silane compound, a trifunctional or higher functional silane compound and / or a vinyl polymerizable group-containing silane compound are added as they are or in the form of an emulsion. It can also be polymerized. In particular, when a vinyl-based polymerizable group-containing silane compound is added, the latter method is preferably used because the vinyl-based polymerizable group can be prevented from being deactivated by heating during the polymerization.

The bifunctional silane compound is a component which is copolymerized during the polymerization of the mixture of the cyclic organosiloxane oligomer and is incorporated into the main skeleton of the polyorganosiloxane chain. Specific examples include diethoxydimethylsilane and dimethoxydimethyl. Silane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, heptadecafluorodecylmethyldimethoxysilane, trifluoropropylmethyldimethoxysilane, octadecylmethyldimethoxysilane, etc. can give. Of these, diphenyldimethoxysilane, diphenyldiethoxysilane, and the like are preferably used because the obtained polyorganosiloxane can increase the refractive index and can impart flame retardancy.

The trifunctional or higher silane compound is a component for imparting rubber elasticity by introducing a crosslinked structure into the polyorganosiloxane by copolymerizing with the mixture of the cyclic organosiloxane oligomer and the bifunctional silane compound. That is, it is used as a crosslinking agent for polyorganosiloxane. Specific examples include tetraethoxysilane,
4-functionality such as methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoropropyltrimethoxysilane, octadecyltrimethoxysilane, etc. Functional alkoxysilane compounds are exemplified. Of these, tetraethoxysilane, methyltriethoxysilane, and methyltrimethoxysilane are preferably used from the viewpoint of high crosslinking efficiency.

The silane compound having a vinyl polymerizable group may be a mixture of the cyclic organosiloxane oligomer,
A component for copolymerizing with a bifunctional silane compound, a trifunctional or higher silane compound, or the like, and introducing a vinyl polymerizable group into a side chain or a terminal of the copolymer. To form a graft point for graft polymerization of the monomer. Further, a radical polymerization initiator causes a radical reaction between the graft active sites to form a cross-linking bond (for example, see Japanese Patent Application Laid-Open No. 10-292).
No. 023) and can be used as a crosslinking agent. In this case, grafting is possible because a part remains as a graft active site.

Specific examples of the vinyl polymerizable group-containing silane compound include, for example, those represented by the following general formula (I):

[0036]

Embedded image (Wherein, R ³ is a hydrogen atom, a methyl group, and R ⁴ is a carbon atom having 1 to 6 carbon atoms.
A monovalent hydrocarbon group, X is an alkoxy group having 1 to 6 carbon atoms, a is 0, 1 or 2, and p is a number of 1 to 6), a silane compound represented by the general formula (II):

[0037]

Embedded image (Wherein R ⁴ , X, a, and p are the same as those in the general formula (I)), a general formula (III):

[0038]

Embedded image (Wherein R ⁴ , X, a, and p are the same as those in the general formula (I)), and a silane compound represented by the general formula (IV):

[0039]

Embedded image Wherein R ⁴ , X, a, and p are the same as in the general formula (I), and R ⁵ is a divalent hydrocarbon group having 1 to 6 carbon atoms, a silane compound represented by the general formula (V) :

[0040]

Embedded image (Wherein, R ⁴ , X, a, and p are the same as those in the general formula (I), and R ⁶ represents a divalent hydrocarbon group having 1 to 18 carbon atoms).

Specific examples of R ^{4 in} the general formulas (I) to (V) include, for example, an alkyl group such as a methyl group, an ethyl group, and a propyl group, a phenyl group, and the like. Examples thereof include an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group. Specific examples of R ^{5 in} the general formula (IV) include a methylene group, an ethylene group, a propylene group, and a butylene group. Specific examples of R ⁶ in the general formula (V) include a methylene group, an ethylene Group, propylene group, butylene group and the like.

Specific examples of the silane compound represented by the general formula (I) include, for example, β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyl Oxypropyldimethylmethoxysilane, γ-methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyldiethoxymethylsilane,
γ-methacryloyloxypropyltripropoxysilane, γ-methacryloyloxypropyldipropoxymethylsilane, γ-acryloyloxypropyldimethylmethoxysilane, γ-acryloyloxypropyltrimethoxysilane, etc. are silane compounds represented by the general formula (II). Specific examples include p-vinylphenyldimethoxymethylsilane, p-vinylphenyltrimethoxysilane, p-vinylphenyltriethoxysilane,
Specific examples of the silane compound represented by the general formula (III) include vinylphenyldiethoxymethylsilane and the like.
Specific examples of the silane compound represented by the general formula (IV) include, for example, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. Allylmethyldimethoxysilane, allylmethyldiethoxysilane Specific examples of the silane compound represented by general formula (V) include allyltrimethoxysilane, allyltriethoxysilane, and the like include mercaptopropyltrimethoxysilane, mercaptopropyldimethoxymethylsilane, and the like.
Among them, the silane compounds represented by the general formulas (I), (II) and (V) are preferably used from the viewpoint of economy.

When the vinyl-based polymerizable group-containing silane compound is of the trialkoxysilane type, it also functions as a crosslinking agent.

The ratio of the mixture of the cyclic organosiloxane oligomer, the bifunctional silane compound, the trifunctional or higher silane compound, and the silane compound having a vinyl polymerizable group used in the polymerization is usually from 40 to 40% of the mixture of the cyclic organosiloxane oligomer. 100%, even 50-99%, 2
Functional silane compound 0 to 60%, further 0 to 50%, 3
More than functional silane compound 0 to 60%, furthermore 0.5 to
50%, silane compound containing vinyl polymerizable group 0-60
%, More preferably 0.5 to 50%.

The bifunctional silane compound is an optional component, but if the proportion is too large, the stability of the resulting polyorganosiloxane latex tends to decrease.

The above-mentioned trifunctional or higher functional silane compound is an optional component. However, if its use ratio is too large, the stability of the resulting polyorganosiloxane-based latex tends to decrease.

The vinyl-based polymerizable group-containing silane compound is an optional component, but if its use ratio is too large, the stability of the resulting polyorganosiloxane-based latex tends to decrease.

The coefficient of variation of the particle size distribution of the polyorganosiloxane latex obtained by these methods is preferably from 10 to 100%, more preferably from 20 to 50%.
%. The polyorganosiloxane-based latex is
The solid component obtained by drying at 0 ° C. for 5 days has a toluene-insoluble content of preferably 0 to 100%, more preferably 0 to 100% when immersed in toluene at room temperature for 24 hours.
~ 95%. When the toluene-insoluble content is 0 to 30%, the weight-average molecular weight in terms of polystyrene of the portion soluble in toluene is preferably 5,000 to 500,000, and more preferably 10,000 to 300,000. When the polyorganosiloxane-based latex satisfies these conditions, it is preferable in terms of good physical properties when used as a flame retardant or an impact resistance modifier.

When a polyorganosiloxane-based solid or powder is recovered from the polyorganosiloxane-based latex obtained by the above-mentioned polymerization in an emulsified state, a usual method, for example, calcium chloride, magnesium chloride, magnesium sulfate, etc. may be added to the latex. The latex is coagulated by adding an inorganic acid and an organic acid such as a metal salt, hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid, and after washing with (hot) water,
A method of dehydration and drying is used. Also, a spray drying method can be used.

[0050]

EXAMPLES The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

The measurements and tests in the following Examples and Comparative Examples were performed as follows. [Polymerization conversion rate] The latex was placed in a hot air dryer at 120 ° C for 1 hour.
After drying for an hour, the amount of the solid component was determined, and the amount was calculated by the formula: solid component amount / prepared monomer amount × 100 (%). [Number average particle size] As a measuring device, Lead & North Wrap Instruments (LEED & NORTHRUP I
NSTRUMENTS) MICROTRAC U
Using PA, the number average particle diameter (μm) and the variation coefficient of the particle diameter distribution (standard deviation / number average particle diameter (%)) were measured by a light scattering method. [Weight average molecular weight] The weight average molecular weight was measured by gel permeation chromatography. The measurement sample was prepared by dissolving a solid obtained by drying a polyorganosiloxane-based latex at 50 ° C. for 5 days in THF so as to have a concentration of 1% (weight / volume%). The measuring device is TSKgel CM
Using an HLC-8020 chromatograph manufactured by Tosoh Corporation equipped with an Hxl column, the number average molecular weight in terms of polystyrene was determined using THF as a mobile phase. . [Toluene-insoluble content] 0.5 g of a solid obtained by drying a polyorganosiloxane-based latex at 50 ° C for 5 days was immersed in 80 ml of toluene at room temperature for 24 hours.
After centrifugation at 60 rpm for 60 minutes, the weight fraction (%) of the solid or the powder insoluble in toluene was measured.

Examples 1-3, Comparative Examples 1-4 300 parts of pure water, 100 parts of a mixture obtained by mixing a cyclic dimethylsiloxane oligomer in the proportions shown in Table 1, furthermore dodecylbenzenesulfonic acid (DBSA) and dodecylbenzenesulfone A mixture obtained by mixing sodium acid salt (SDBS) in an amount shown in Table 1 was mixed with a homomixer at 10,000.
The emulsion was prepared by stirring at rpm for 5 minutes. This emulsion was charged into a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, and thermometer.
After the temperature was raised to about 40 minutes over about 40 minutes, the reaction was performed for 4 hours. Then, after cooling to 25 ° C. and maintaining for 20 hours, the pH of the system was returned to 8.0 to 8.5 with sodium hydroxide to complete the polymerization. Solid content concentration of the obtained latex, polymerization conversion,
The number average particle diameter, the coefficient of variation of the particle diameter distribution, and the weight average molecular weight of the polyorganosiloxane were measured, and the results are shown in Table 1.

In the table, D3 is hexamethylcyclotrisiloxane, D4 is octamethylcyclotetrasiloxane, D5 is decamethylcyclopentasiloxane, D6
Represents a cyclic dimethylsiloxane oligomer which is dodecamethylcyclohexasiloxane and D7 represents tetradecamethylcycloheptasiloxane.

[0054]

[Table 1] From Table 1, it can be seen that when the cyclic dimethylsiloxane oligomer mixture having the specific composition is used, the number average particle diameter is smaller than when a single cyclic dimethylsiloxane oligomer or a cyclic dimethylsiloxane oligomer mixture having a specific composition is not used. It is understood that it is possible. When a single cyclic dimethylsiloxane oligomer is used to obtain a number average particle diameter obtained by using a mixture of cyclic dimethylsiloxane oligomers, the emulsifier (SDBS +
DBSA) is necessary.

Examples 4-6 and Comparative Examples 4-7 Cyclic dimethylsiloxane oligomer mixture (D35
%, D4 69.5%, D5 20%, D6 5%, D
7 0.5%), tetraethoxysilane (TEOS),
Mercaptopropylmethyldimethoxysilane (MPrD
MS) and γ-methacryloyloxypropyltrimethoxysilane (TSMA) in the amounts shown in Table 2 to Example 1
Polymerization was carried out in an emulsified state in the same manner as in Example 1 to obtain a polyorganosiloxane-based latex. Table 2 shows the results.

[0056]

[Table 2] From Table 2, even when a tetrafunctional silane compound or a vinyl-based polymerizable group-containing silane compound is used in combination, the use of a cyclic dimethylsiloxane oligomer mixture is the same as the case of using a single cyclic dimethylsiloxane oligomer. It can be seen that an emulsifier having a smaller number average particle diameter can be obtained.

Example 7 A 5-neck flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition port, and a thermometer was charged with the components (parts) pure water 190 SDBS 1.5 potassium persulfate 0 .002 was charged.

Next, the temperature was raised to 70 ° C. while replacing the system with nitrogen, and 1 part of butyl acrylate (BA) and styrene (S
t) A mixed solution consisting of 2 parts was added all at once and stirred for 1 hour to complete the polymerization to obtain a BA / St copolymer latex. The polymerization conversion was 99%. The obtained latex has a solid content of 2.3% and a number average particle size of 0.01 μm.
m, and the coefficient of variation of the particle size distribution was 34%.

Separately, cyclic dimethylsiloxane oligomer mixtures (D3 5%, D4 70%, D5 20%, D5
65%) with a homomixer at 1000
The mixture was stirred at 0 rpm for 5 minutes to prepare an emulsion of the polyorganosiloxane-forming component.

Component Amount (parts) Pure water 70 SDBS 0.5 Cyclic dimethyl siloxane oligomer mixture 95 γ-methacryloyloxy propylmethyldimethoxysilane 2 Then, the latex containing BA / St copolymer is 90
After maintaining the temperature at ℃ and adding 2 parts of DBSA and 18 parts of pure water to the system to adjust the pH of the system to 1.2, the emulsion of the polyorganosiloxane-forming component was equally divided into four portions and added at once every hour. did. After stirring was continued for 1 hour after the addition was completed, the mixture was cooled to 25 ° C and left for 20 hours. Thereafter, the polymerization was terminated by adjusting the pH to 8.9 with sodium hydroxide, and a polyorganosiloxane-based latex was obtained. The polymerization conversion of the polyorganosiloxane-forming component was 87%. The solids concentration of the latex was 24%.

The obtained latex (solid content: 100 parts) was maintained at 60 ° C., and 0.2 parts of tert-butyl peroxyisopropyl carbonate was added thereto under a nitrogen stream to add 1 part.
Stirred for 0 minutes. Subsequently, 0.02 part of sodium formaldehyde sulfoxylate, 0.01 part of disodium ethylenediaminetetraacetate and 0.002 part of ferrous sulfate were added.
The resulting mixture was stirred for 2 hours, and crosslinking was allowed to proceed by a radical reaction to obtain a polyorganosiloxane latex. The amount of emulsifier used in the manufacture of latex (SDB
Table 3 shows the measurement results for the (S + DBSA) amount, the number average particle size, the variation coefficient of the particle size distribution, and the toluene-insoluble content.

Comparative Example 8 A polyorganosiloxane latex was obtained in the same manner as in Example 7 except that D4 was used instead of using the cyclic dimethylsiloxane oligomer mixture. Table 3 shows the results
Shown in

Comparative Example 9 A polyorganosiloxane latex was obtained in the same manner as in Comparative Example 8, except that the amount of SDBS used in the polymerization of the BA / St copolymer was changed to 3.5 parts.
Table 3 shows the results.

[0064]

[Table 3] According to Table 3, even when polymerized using a vinyl polymer as a seed, the number average particle size of the same emulsifier is larger when a cyclic dimethylsiloxane oligomer mixture satisfying a specific composition is used than when a single cyclic dimethylsiloxane oligomer is used. It can be seen that a smaller diameter can be obtained. In addition, it can be seen that more emulsifiers are required if a single cyclic dimethylsiloxane oligomer is used to obtain the number average particle size obtained using a cyclic dimethylsiloxane oligomer mixture.

[0065]

According to the present invention, a polyorganosiloxane latex having a number average particle size of 0.1 μm or less can be obtained with a small amount of an emulsifier.

Claims (3)

[Claims] 1. A compound of the general formula: (Wherein R ¹ and R ² represent a methyl group, an ethyl group, a propyl group,
A monovalent hydrocarbon group having 1 to 10 carbon atoms such as a phenyl group, and R ¹ and R ² may be the same or different. Has a number average particle diameter of 0.008 to
A process for producing a 0.1 μm polyorganosiloxane-based latex, wherein the mixture of cyclic organosiloxane oligomers comprises 0 to 10% by weight of trimers, 40 to 95% by weight of tetramers, 5 to 40% by weight of pentamers, 6 to 10% by weight or more
A production method characterized by comprising: 2. The method for producing a polyorganosiloxane-based latex according to claim 1, wherein the mixture of cyclic organosiloxane oligomers is a mixture of cyclic dimethylsiloxane oligomers. 3. The emulsion polymerization is carried out in an acidic state at a pH of 3 or less.
The method for producing a polyorganosiloxane-based latex according to claim 1 or 2, wherein the method is carried out by heating to 60 ° C or higher.