JPH07173294A - Production of oil-in-water type organopolysiloxane emulsion - Google Patents

Abstract

PURPOSE:To provide an oil-in-water type organopolysiloxane emulsion which has a small mean particle diameter and is stable without separation even during storage. CONSTITUTION:100 pts.wt. liquid organopolysiloxane having a viscosity at 25 deg.C of 10,000 to 1,000,000cSt is dispersed by agitation in 1-20 pts.wt. aqueous solution of an ionic emulsifier. The dispersion is mixed with 1-50 pts.wt. nonionic emusifier, and the mixture is subjected to high shear agitation to reduce the particle diameter and then diluted with water to form an emulsion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an oil-in-water type organopolysiloxane emulsion, and more particularly to a method for producing an oil-in-water type organopolysiloxane emulsion which does not separate even after being left for a long time and has a high storage stability.

[0002]

2. Description of the Related Art As a method for producing an oil-in-water emulsion of liquid organopolysiloxane, a stirring device such as a homomixer or a high-pressure homogenizer which can impart a high-speed shearing force to the liquid organopolysiloxane using an emulsifier is used. A method of emulsification using a well-known method is based on a so-called emulsion polymerization method, in which a low molecular weight cyclic polysiloxane is used as a starting material and is polymerized in an emulsified and dispersed state with a strong acid or a strong alkaline substance as a catalyst. The method is also known (Japanese Patent Publication No. 41-139).
No. 95, Japanese Examined Patent Publication No. 44-20116), which makes it possible to produce an oil-in-water emulsion of a considerably high-viscosity organopolysiloxane.

However, in the production method using the homomixer or the high-pressure homogenizer, it is essential that the object to be emulsified is sucked into the holes provided in the stator and is subjected to the shearing action of the high-speed stirring blade. When it has a high viscosity, it becomes difficult to inhale it, so that the production cannot be performed, and the emulsion obtained by the above emulsion polymerization method has a small particle size with an average particle size of about 0.2 μm and good stability. However, since about 10% of the starting organopolysiloxane remains as a volatile low molecular weight product in the production process, using these organopolysiloxane emulsions makes it volatile in the drying process. Of low molecular weight organopolysiloxane volatilizes, polluting the surrounding environment and causing poor electrical continuity of the electrical contacts of the surrounding electrical equipment. There is a problem to be or is.

[0004]

Therefore, in the method for producing the oil-in-water type organopolysiloxane emulsion, the high-viscosity liquid organopolysiloxane is not subjected to emulsion polymerization, but the organopolysiloxane is formed into an emulsion using a complex emulsifying device. There has been proposed a method of
63-125530), according to which an oil-in-water type organopolysiloxane emulsion having an average particle size of dispersed particles of about 0.5 μm and excellent stability can be obtained. When stirring a high-viscosity fluid composition containing polysiloxane as a main component, a large viscous resistance force is applied to the shaft of the stirrer, which may damage the stirrer and its use is limited. There is.

[0005]

The present invention relates to a method for producing an oil-in-water organopolysiloxane emulsion which has solved the above disadvantages and drawbacks in the conventional method, and has a viscosity at 25 ° C of 10,000 cS to 1,000,000.
100 parts by weight of liquid organopolysiloxane which is cS is added to 10 to 20 parts by weight of an aqueous ionic emulsifier solution, stirred and dispersed, and then 1 to 50 parts by weight of a nonionic emulsifier is added thereto, and high shear stirring is performed. The feature is that the particle size is reduced and then diluted with water to form an emulsion.

That is, as a result of various studies on the method for easily obtaining an oil-in-water type organopolysiloxane emulsion, the present inventors have found that when a highly viscous organopolysiloxane is put into an aqueous solution containing an ionic emulsifier and stirred,
A large particle pre-emulsion of the organopolysiloxane is obtained. Then, it was found that a stable oil-in-water emulsion having a small particle size can be obtained by stirring the mixture under high shear in the presence of a nonionic emulsifier, and the objective is to dilute it by adding a predetermined amount of water to it. The present invention was completed by confirming that an oil-in-water type organopolysiloxane emulsion described below was obtained. This will be described in more detail below.

[0007]

In the method for producing an oil-in-water type organopolysiloxane emulsion according to the present invention, a highly viscous organopolysiloxane is put into an aqueous solution containing an ionic emulsifier and stirred, and then the mixture is added in the presence of a nonionic emulsifier. High-shear stirring is followed by addition of water, and the high-viscosity organopolysiloxane used here has a viscosity at 25 ° C. of 10,000 cS to 1,000,000 cS, preferably 50,0.
It is a liquid organopolysiloxane that is 00 to 500,000 cS.

Typical examples of the organopolysiloxane include dialkylpolysiloxane and alkylarylpolysiloxane. In these, a part of the alkyl group is an amino group-containing organic group, hydrogen group, vinyl group or allyl group. It may be substituted with an unsaturated alkyl group such as an epoxy group-containing organic group, a mercapto group-containing organic group, a carboxyl group-containing organic group, a halogenated alkyl group, etc., and these have a linear, cyclic, or branched structure. It may be branched, but is preferably linear dimethylpolysiloxane or methylphenylpolysiloxane. This viscosity is 10,000-1,000,000 cS
The organopolysiloxane in the range of 1 is not limited to one kind, and it is composed of a mixture of two or more kinds of organopolysiloxane in the range of viscosity of 50 to 10,000,000 cS, resulting in a viscosity of 10,000 to Any liquid organopolysiloxane having a high viscosity of 1,000,000 cS may be used.

The liquid organopolysiloxane is first put into an aqueous solution containing an ionic emulsifier and stirred, and the ionic emulsifier may be an anionic emulsifier, a cationic emulsifier or an amphoteric emulsifier. .
Examples of the anionic emulsifier include sodium alkyl sulfate, ammonium alkyl sulfate, sodium polyoxyethylene alkyl sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, ammonium polyoxyethylene alkyl ether ether, and ammonium polyoxyethylene alkylphenyl ether sulfate. Examples thereof include tetraalkylammonium chloride, alkylamine hydrochloride, coconutamine hydrochloride and coconutamine acetate, and examples of amphoteric emulsifiers include N-acylamidopropyl-N, N-dimethylammoniobetaines and N-acyl. Examples thereof include amidopropyl-N, N'-dimethyl-N'-β-hydroxypropylammoniobetaine. Anionic emulsifiers are preferable, and sodium polyoxyethylene alkyl sulfate and sodium polyoxyethylene alkylphenyl ether sulfate are particularly preferable.

These ionic emulsifiers are used as an aqueous solution. When the concentration of the ionic emulsifier at this time is less than 0.1% by weight, it is difficult to disperse the liquid organopolysiloxane by stirring. Since the particle size of the oil-in-water organopolysiloxane emulsion obtained as a result becomes large and the stability becomes poor, it is required to be in the range of 0.1 to 10% by weight, which is preferably It is preferably 0.5 to 5% by weight.

In the method of the present invention, the above-mentioned liquid organopolysiloxane is added to the aqueous solution of the ionic emulsifier and stirred. The amount of the aqueous ionic emulsifier solution at this time is 100 parts by weight of the liquid organopolysiloxane. On the other hand, if it is less than 1 part by weight, the viscosity after the liquid organopolysiloxane is added is high and stirring dispersion becomes difficult. If it exceeds 20 parts by weight, the finally obtained oil-in-water organopolysiloxane emulsion has It is required to be 1 to 20 parts by weight because of a large lack of stability, but the preferable range is 5 to 15 parts by weight. This stirring may be performed with a homomixer, an ajihomo mixer, or the like, but the stirring time after the liquid organopolysiloxane is charged is generally 10 minutes to 1 hour since it is sufficient that the liquid organopolysiloxane is sufficiently dispersed. The result is a large particle pre-emulsion of the liquid organopolysiloxane.

In the method of the present invention, a nonionic emulsifier is then added to the mixture, and the mixture is emulsified and dispersed by high shear stirring. The nonionic emulsifier used here is polyoxyethylene higher alcohol ether or polyoxyethylene. Examples are ethylene alkyl phenyl ether, sorbitan monoalkylate, sorbitanial chelate, polyoxyethylene sorbitan monoalkylate, polyoxyethylene sorbitanial chelate, polyoxyethylene sorbitan tetraalkylate, glycerol monoalkylate, etc. Although an emulsifier or a silicone-based emulsifier may be used, it is preferable that the hydrophilic / lipophilic balance value (HLB value) of these is in the range of 7.0 to 19.0.

If the amount of this nonionic emulsifier added to the pre-emulsion obtained in the preceding step is less than 1% by weight, the particle size of the finally obtained oil-in-water organopolysiloxane emulsion will be large and the stability will be improved. If it is more than 50 parts by weight, the viscosity of the finally obtained oil-in-water organopolysiloxane emulsion will be too high, and it will be difficult to produce the emulsion.
A range of 1 to 50 parts by weight is required, but a preferable range is 5 to 20 parts by weight. Further, when the nonionic emulsifier is added, the particle size of the emulsion which is stirred under high shear can be reduced, and the stirring time is generally 30 minutes to 1 hour.

The oil-in-water type organopolysiloxane emulsion thus obtained is then added with a predetermined amount of water as water dilution and stirred to obtain an oil-in-water type organopolysiloxane emulsion having a desired concentration. Become. The stirring device used in this series of manufacturing steps may be a homomixer or an ajihomomixer, but in order to carry out this smoothly, the contents of the container can be rotated at low speed throughout the container. It is preferable to use a composite emulsifying apparatus provided with both a stirring means composed of blades and a disk-type stirring means having a tooth-like projection on the periphery and capable of rotating at high speed.

The present invention relates to a method for producing an oil-in-water type organopolysiloxane emulsion, which has a viscosity at 25 ° C. of 10,000 cS to 1,000,000 cS as described above.
100 parts by weight of the liquid organopolysiloxane is added to 1 to 20 parts by weight of an aqueous ionic emulsifier solution and stirred and dispersed. The feature is that the particles are made into a particle size and then diluted with water to form an emulsion, which makes it possible to easily obtain a stable oil-in-water organopolysiloxane emulsion having a small particle size. Advantages are given.

[0016]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Example 1 An anchor type stirring device (a) that can stir the entire chamber in a stainless steel container (inner diameter 30 cm) having a capacity of 5 L and the disc type stirring shown in FIG. The stainless steel composite emulsification device shown in FIG. 1 equipped with two types of stirring devices, a high shearing device (b) having means (diameter 4 cm), was provided, and polyoxyethylene (additional mol number = 3) was provided in this container.
126 g of 1.2% aqueous solution of sodium lauryl ether sulfate was added.

Then, a stirring device (a) is added here at 5 rpm,
Viscosity is 500,0 while rotating the stirring device (b) at 100 rpm.
1,500 g of dimethylpolysiloxane blocked with trimethylsiloxy groups at both ends of 00cS was added for about 20 minutes, and after the addition was completed, the mixture was stirred for 30 minutes under the same stirring conditions to obtain a translucent grease-like composition. So
Polyoxyethylene (additional mol number = 6) lauryl ether 60g and polyoxyethylene (additional mol number =
20) 120 g of lauryl ether was added, and after the addition, high shear stirring was carried out for 45 minutes with the stirring device (a) at 15 rpm and the stirring device (b) at 1,000 rpm. As a result, a uniform transparent grease-like composition was obtained. , Then add this agitator (a) 1
5 rpm, stirring device (b) 300 rpm, deionized water here
When 1,190 g was added and the mixture was stirred for another 30 minutes, a uniform emulsion oil-in-water organopolysiloxane emulsion with an average particle size of 0.48 μm and a viscosity of 60 centipoise was obtained. It did not separate even after being left for 1 month and was extremely stable.

Example 2 In place of the 500,000 cS dimethylpolysiloxane used in Example 1, 25 parts by weight of dimethylsiloxy group capped at both ends with a trimethylsiloxy group having a viscosity of 16,000,000 cS and dimethylpolysiloxane blocked with trimethylsiloxy at both ends of a viscosity of 500 cS were used. Viscosity of 330,000, mixed with 75 parts by weight of polysiloxane
Example 1 except that dimethylpolysiloxane of cS was used
When treated in exactly the same manner as above, an oil-in-water type organopolysiloxane emulsion in the form of white emulsion was obtained, which had a viscosity of 85 centipoise and an average particle size of 0.55 μm. No separation was observed even after standing for a month, and the stability was extremely high.

Comparative Example 1 The same stainless steel compound emulsification device as in Example 1 was installed in the same stainless steel container as in Example 1, and 1,500 g of dimethylpolysiloxane having a viscosity of 500,000 cS and having trimethylsiloxy groups at both ends blocked therein. , Polyoxyethylene (additional mol number = 6) lauryl ether 60 g and polyoxyethylene (additional mol number = 20) lauryl ether 120 g were added, and polyoxyethylene as phase inversion water (additional mol number =
3) 1.2% aqueous solution of sodium lauryl ether sulfate 12
After setting the stirrer (a) to 15 rpm to add 6 g,
Further, when the stirring device (b) was adjusted to 1,000 rpm, in this case, the stirring device was automatically stopped due to overload, and the emulsification could not be achieved.

Comparative Example 2 The same stainless steel compound emulsification device as in Example 1 was installed in the same stainless steel container as in Example 1, and polyoxyethylene (additional mol number = 6) lauryl ether 60 was placed in this container.
g, polyoxyethylene (additional mole number = 20) 120 g of lauryl ether and polyoxyethylene (additional mole number =
3) 1.2% aqueous solution of sodium lauryl ether sulfate 12
Charge 6 g, stirrer (a) 5 rpm, stirrer (b)
Is set to 100 rpm and the viscosity is 500,000 while stirring.
When 1,500 g of dimethylpolysiloxane capped with trimethylsiloxy groups at both ends of cS was added and the agitator (b) was tried to be adjusted to 1,000 rpm, the agitator automatically stopped due to overload, thus achieving emulsification. I couldn't.

[0021]

According to the above-described method of the present invention, in the conventional phase inversion method, a large resistance is generated in the stirrer at the initial stirring of the high-viscosity organopolysiloxane and the emulsifier, and the phase inversion is performed at the time of phase inversion. It was difficult to produce an emulsion because of the large viscous resistance that occurs when high-shear stirring is applied to a high-viscosity stirrer. The advantage is given that oil-based organopolysiloxane emulsions can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a composite emulsification device used in an example of the present invention.

2A and 2B are vertical cross-sectional views of a disk stirring means in a compound emulsifying apparatus used in an example of the present invention, in which FIG. 2A is a disk stirring apparatus at an intermediate portion thereof, and FIG. 2 shows the disk stirring device of FIG.

Claims (2)

[Claims] 1. Viscosity at 25 ° C from 10,000 cS to 1,000,0
100 parts by weight of liquid organopolysiloxane which is 00 cS,
Pour into 1 to 20 parts by weight of the aqueous ionic emulsifier solution and stir-disperse it, then add 1 to 50 parts by weight of the nonionic emulsifier, reduce the particle size by high-shear stirring, and then dilute with water. A process for producing an oil-in-water type organopolysiloxane emulsion, which comprises emulsifying the emulsion. 2. An emulsification step comprising: a stirring means comprising stirring blades capable of rotating container contents at a low speed over the entire container; and a disk type stirring means having a tooth-like projection on the periphery and capable of rotating at a high speed. The method for producing an oil-in-water type organopolysiloxane emulsion according to claim 1, which is carried out by a composite emulsifying apparatus.