JPH0653852B2 - Method for producing solid silicone spherical fine particles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing solid silicone spherical fine particles useful as impact resistance improvers, lubricity improvers and the like for thermoplastic resins and thermosetting resins.

2. Description of the Related Art Conventionally, several proposals have been made regarding methods for producing solid silicone spherical fine particles.

For example, an organopolysiloxane having a vinyl group at the terminal of the molecular chain and an organohydrogenpolysiloxane having a hydrogen atom bonded to a silicon atom are made into an emulsion using water and a surfactant, and a platinum-based catalyst is added to the emulsion. , A method of curing the organosiloxane by heating to obtain an emulsion containing silicone particles (JP-A-56)
-36546) and a method of obtaining silicone spherical particles cured from the above emulsion by a spray drying method (JP-A-62-257939).

However, in the conventional method for producing silicone spherical fine particles using this type of hydrosilylation reaction, silicone spherical fine particles are obtained from organopolysiloxane having a functional group (for example, a nitrogen atom-containing functional group) that is a catalyst poison to a platinum-based catalyst. Was difficult to manufacture.

On the other hand, a method for producing solid silicone spherical fine particles using ultraviolet rays has also been proposed (Japanese Patent Publication No. 63-65692). This method comprises: (i) an organopolysiloxane having on average at least two vinyl-bonded and butenylene-grouped silicon-bonded olefin groups per molecule; (ii) silicon-bonded hydrogen and 1-6 Two different organopolysiloxanes comprising an aliphatic unsaturated group-free hydrogen-containing organopolysiloxane containing an average of at least two hydrogen groups selected from the group consisting of mercaptoalkyl groups having 4 carbon atoms. Is emulsified and irradiated with ultraviolet rays to obtain solid silicone spherical particles, but this method has a problem that unreacted molecules remain and the obtained particle size is large.

The present invention has been made in view of the above circumstances, and it is possible to produce solid silicone spherical fine particles from organopolysiloxane having a functional group that becomes a catalyst poison to a platinum-based catalyst,
Therefore, it is an object of the present invention to provide a method for producing solid silicone spherical fine particles having a very small particle size, which is easy to modify with a functional group.

Means and Actions for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, as a raw material for obtaining solid silicone spherical fine particles, an aliphatic non-aliphatic compound having a silicon atom bonded in one molecule. One or more saturated groups and one or more mercapto-containing groups represented by the following formula (1) -R-SH (1) (wherein R is a divalent organic group having 1 to 10 carbon atoms): Further, an organopolysiloxane having a total of three or more of these aliphatic unsaturated groups and mercapto-containing groups is used, and this is emulsified to form emulsion particles having an average particle size of 20 μm or less, and then the emulsion particles are photosensitized. It was found that by curing the emulsion particles by irradiating them with ultraviolet rays in the presence of a sensitizer, it is possible to obtain solid silicone spherical fine particles having a very small particle size, which is easily modified with a functional group. .

That is, as described above, two kinds of organopolysiloxane, that is, an organopolysiloxane having an aliphatic unsaturated group and an organopolysiloxane having a mercapto-containing group are used, and these are emulsified and then irradiated with ultraviolet rays to form an emulsion. It is known to cure particles, but
In this method, unreacted molecules remain, and the obtained particles have a considerably large particle size. On the other hand, by using the above-mentioned organopolysiloxane having both an aliphatic unsaturated group and a mercapto-containing group in the same molecule, all the molecules participate in the reaction, the reaction is likely to be completed, and there is little aggregation between particles. Therefore, it is possible to easily and surely obtain silicone spherical fine particles having a particle diameter of about 0.1 to 20 μm. Further, since the above organopolysiloxane is cured by irradiation with ultraviolet rays, a catalyst poison is taken into consideration like a hydrosilylation reaction using a platinum-based catalyst. Without doing so, it was found that it is easy to modify with various functional groups such as nitrogen atom-containing functional groups, and the present invention has been completed.

Accordingly, the present invention provides an aliphatic unsaturated group bonded to a silicon atom in one molecule and the following formula (1) -R-SH (1) (wherein R is a divalent 1 to 10 carbon atom). Which is an organic group) and has an average particle diameter of 20 μm or less by emulsifying an organopolysiloxane having one or more mercapto-containing groups represented by each and a total of three or more of these aliphatic unsaturated groups and mercapto-containing groups. Provided is a method for producing solid silicone spherical fine particles, which comprises forming emulsion particles and then irradiating the emulsion particles with ultraviolet rays in the presence of a photosensitizer to cure the emulsion particles.

Hereinafter, the present invention will be described in more detail.

The method for producing solid silicone spherical fine particles according to the present invention,
As a starting material, an organopolysiloxane having an aliphatic unsaturated group and a mercapto-containing group at the same time in the same molecule, more specifically, at least one (preferably 3) of organic groups bonded to a silicon atom in one molecule. 10 to 10) are aliphatic unsaturated groups such as vinyl group, allyl group and butenyl group, and at least one (preferably 3 to 10) of the remaining organic groups has the formula (1) -R- SH ...... (1) (wherein R represents a divalent organic group having 1 to 10 carbon atoms, for example, an unsubstituted or substituted alkylene group), and is the aliphatic unsaturated group An organopolysiloxane having a total number of groups and mercapto-containing groups of 3 or more, preferably 5 to 30, is used.

In this case, the remaining organic group other than the mercapto-containing group of the aliphatic unsaturated group is a methyl group, an ethyl group, an alkyl group such as an octyl group, a halogen group, a functional group-substituted alkyl group substituted with a cyano group, etc. However, it is preferable that 80 mol% or more of all the organic groups are methyl groups from the viewpoint of lubricity of fine particles. Further, in the present invention, a nitrogen-containing functional group such as an organic group, for example, It is possible to carry out various functional group modification by using 1 to 10 mol% of the above.

The molecular structure of the organopolysiloxane may be linear or cyclic. The viscosity is preferably 100 to 10,000 cp at 25 ° C.

In the present invention, this organopolysiloxane is emulsified, but a known method can be adopted as an emulsifying method. Generally, water and a surfactant are added to the above-mentioned organopolysiloxane, and this is emulsified using a commercially available homogenizer, etc., but the surfactant used here should be one that can emulsify the organopolysiloxane. Anything may be used, and examples thereof include nonionic emulsifiers such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and polyvinyl alcohol, and anionic emulsifiers such as sodium alkylbenzenesulfonate, sodium alkylsulfate, and carboxymethylcellulose. These may be used alone or in combination of two or more. In the present invention, the emulsion prepared has an emulsion particle size of 20 μm or less, preferably 0.1 to 10 μm.
In this case, in order to obtain emulsion particles having such a particle size, in order to emulsify the same, an organopolysiloxane and an emulsifying agent are mixed in advance, and water is gradually added to the mixture so that W It is preferable to use a phase inversion emulsification method in which the / O type emulsion is phase-inverted to the O / W type emulsion. The amount of water required for this phase inversion is preferably in the range of 10 to 300 parts by weight with respect to 100 parts by weight of organopolysiloxane.

In the present invention, the emulsion particles of the organopolysiloxane are irradiated with ultraviolet rays in the presence of a photosensitizer to cure the emulsion particles. In this case, the photosensitizer may be previously blended with the above-mentioned organopolysiloxane to form emulsion particles together, or may be added to the emulsion formed as described above. The blending amount is an amount effective for converting the organopolysiloxane into a solid state by irradiation with ultraviolet rays, and is usually 1 to 10 parts by weight with respect to 100 parts by weight of the organopolysiloxane. The photosensitizer used here may be any as long as it has a photosensitizing effect, for example, acetophenone, benzophenone, propiophenone,
Xanthone, anthraquinone, fluorenone, 3-methyl-acetophenone, 3-bromoacetophenone, 4-
Methylbenzophenone, benzaldehyde, arbazole, triphenylamine, etc. can be mentioned.

When the emulsion obtained as described above is irradiated with ultraviolet rays, the flowable organopolysiloxane becomes solid silicone within the emulsion particles, but the method of ultraviolet irradiation here is to electrically protect the emulsion. A known method such as a method of introducing an ultraviolet ray source, a method of applying a suitable light source such as a mercury vapor lamp, an electric arc, or sunlight from the outside of the emulsion can be adopted. The speed of converting emulsion particles to solid particles is
Since it is directly related to the intensity of the ultraviolet light incident on the organopolysiloxane, it can be irradiated with ultraviolet light in consideration of the intensity of the ultraviolet light source, the distance from the emulsion, the nature of the intervening space, and the like.

The method of separating the obtained solid silicone spherical fine particles from the emulsion after irradiation with ultraviolet rays is not particularly limited, but precipitation is performed by adding salts such as Na ₂ SO ₄ , MgSO ₄ , ZnSO ₄ , CaCl ₂ , NaCl, and KCl. And then salting out by washing with water and drying,
A separation method such as a spray dry method can be adopted.

The solid silicone spherical fine particles of the present invention thus obtained are usually 0.1 to 20 μm, preferably 0.3 to 10 μm.
Since it is a cured product of organopolysiloxane, it has rubber elasticity and excellent lubricity, so it is an impact resistance improver and lubricity improver for thermoplastic resins and thermosetting resins. In addition to being used as an agent, it is also suitably used as an anti-blocking agent for paints and as a filler for cosmetics.

Effects of the Invention According to the present invention, solid silicone spherical fine particles having a very small particle size and having various functional groups can be easily and reliably obtained. Also, solid silicone fine particles can be produced by emulsion polymerization.

Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, parts are parts by weight and viscosity is 25.
The measured value at ° C is shown.

[Example 1] The photosensitizer [Darocur 1173 (trade name of Merck)] is mixed with 30 parts of the organopolysiloxane represented by
Poval PA18 (trade name of Shin-Etsu Chemical Co., Ltd.) 2
After 0 parts and 50 parts of water were added and uniformly mixed with a homogenizer, the mixture was homogenized by passing through a Gaurin homogenizer at a pressure of 300 kg / cm ² to prepare an emulsion. The volume average particle diameter of the obtained emulsion particles was 0.7 μm.

Next, after irradiating with ultraviolet rays (0.16 mW / cm ² ) for 6 hours, Na
_It was salted out with ₂ SO ₄ , washed with ion-exchanged water 3 times, and dried.
The produced solid silicone fine particles were observed by a microscope and found to be spherical fine powder having an average particle size of about 0.7 μm.

10 g of this silicone spherical fine powder was immersed in 200 g of toluene at room temperature for 24 hours, and after toluene was separated by filtration, it was dried at 70 ° C. for 16 hours in a vacuum dryer, and the weight before and after immersion in toluene was compared.

As a result, the amount of toluene extracted was as small as 1.1%, and it was confirmed that the curing of the silicone was almost completed by the irradiation of ultraviolet rays.

Example 2 The following formula In 30 parts of the organopolysiloxane shown by the formula, a surfactant [Newcol 865 (trade name of Nippon Emulsifier Co., Ltd.)] is added.
After 3 parts and 68.5 parts of water were added and uniformly mixed with a homogenizer, this was homogenized by passing through a Gaurin homogenizer at a pressure of 300 kg / cm ² to prepare an emulsion. The volume average particle diameter of the obtained emulsion particles was 0.65 μm.

Next, a photosensitizer [Darocur 1116 (trade name of Merck)] 0.
3 parts was added to the above emulsion and irradiated with ultraviolet rays (0.16 mW / cm ² ) while stirring. After irradiating with ultraviolet rays for 6 hours, it was salted out with Na ₂ SO ₄ , washed with ion-exchanged water 3 times, and dried. As a result of microscopic examination of the produced solid silicone fine particles, it was found that the fine particles were spherical fine powder having an average particle diameter of about 0.7 μm.

In addition, as a result of investigating the weight change due to the immersion in toluene as in Example 1, it was confirmed that the toluene extraction rate was 1.3% and that the curing of the silicone was completed by the irradiation of ultraviolet rays.

Example 3 The following formula After adding 0.3 parts of a surfactant [Newcol 865 (trade name of Nippon Emulsifier Co., Ltd.)] and 68.5 parts of water to 30 parts of the amino-modified organopolysiloxane shown in, and uniformly mixing with a homogenizer, 300 kg / An emulsion was prepared by homogenizing through a Gaurin homogenizer at a pressure of cm ² . The volume average particle size of the obtained emulsion particles is 0.
It was 66 μm.

Next, a photosensitizer [Darocur 1116 (trade name of Merck)] 0.
3 parts was added to the above emulsion and irradiated with ultraviolet rays (0.16 mW / cm ² ) while stirring. After irradiating with ultraviolet rays for 6 hours, it was salted out with Na ₂ SO ₄ , washed with ion-exchanged water 3 times, and dried. As a result of microscopic examination of the produced solid silicone fine particles, it was confirmed that they were spherical fine powders having an average particle diameter of about 0.75 μm. In addition, the presence of amino groups was confirmed. Further, as a result of examining the weight change by dipping in toluene as in Example 1, it was confirmed that the extraction ratio of toluene was 1.0% and the curing of the silicone was completed by the irradiation of ultraviolet rays.

[Comparative example]

The following formula 30 parts of vinylmethylpolysiloxane represented by In Example 1, 3 parts of mercaptopropylmethylpolysiloxane represented by (n = 3 to 6) and 1.2 parts of Darocur 1116 were used.
The emulsion was emulsified with Poval PA-18 in the same manner as above, irradiated with ultraviolet rays, salted out, washed with water, and dried. As a result of examining the produced solid silicone fine particles, spherical fine powder having an average particle diameter of about 50 μm was found to be agglomerated between the particles. In addition, the toluene extraction rate was as high as 6.3%, indicating that there was an organopolysiloxane that did not completely react with ultraviolet rays.

Claims (1)

[Claims] 1. An aliphatic unsaturated group bonded to a silicon atom in one molecule and the following formula (1) -R-SH (1) (wherein R is a divalent organic group having 1 to 10 carbon atoms). An emulsion having an average particle size of 20 μm or less by emulsifying an organopolysiloxane having one or more mercapto-containing groups represented by each group) and having three or more of these aliphatic unsaturated groups and mercapto-containing groups in total. A method for producing solid silicone spherical fine particles, characterized in that after forming the particles, the emulsion particles are irradiated with ultraviolet rays in the presence of a photosensitizer to cure the emulsion particles.