JPH0470335B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a polymethylsilsesquioxane powder and a method for producing the same, and more specifically, to polymethylsilsesquioxane powder having a narrow particle size distribution and an extremely large amount of contact charge. This invention relates to powder and its manufacturing method. [Technical background of the invention and its problems] It has been known that polymethylsilsesquioxane can be obtained by hydrolyzing and condensing trifunctional silanes such as methyltrichlorosilane. For example, Belgian Patent No. 572412 discloses that methyltrichlorosilane is hydrolyzed in a spray or dropped into a large amount of water with stirring to be hydrolyzed to obtain solid polymethylsilsesquioxane. The method is described. However, with this method, there is a problem that the heat generated during the hydrolysis reaction is large and a large amount of hydrogen chloride is produced as a by-product, which corrodes the equipment. The drawback was that methyltrichlorosilane remained, and a relatively large amount of chlorine atoms remained. Furthermore, this method also had the disadvantage of poor production efficiency due to the use of a large amount of water. As a way to eliminate the above drawbacks, JP-A-54-
Publication No. 72300 discloses that methyltrialkoxysilane and/or its partial hydrolyzate is mixed in an aqueous solution containing an alkaline earth metal hydroxide or an alkali metal carbonate, and the amount of chlorine is 0.1 to 5.0% by weight.
A method for hydrolyzing and condensing is disclosed. However, in this method, relatively large amounts of alkaline earth metals and alkali metals remain in the polymethylsilsesquioxane powder produced, so when used as fillers for various synthetic resins, there is a problem that it easily absorbs moisture. Ta. This method also has the disadvantage that the amount of chlorine in the raw material methyltrialkoxysilane and/or its partial hydrolyzate must be adjusted to 0.1 to 5.0% by weight. The present inventor first prepared a catalyst using methyltrialkoxysilane and/or its partially hydrolyzed condensate in an amount sufficient to neutralize the chlorine atoms present in the silane and/or its partially hydrolyzed condensate. By hydrolysis and condensation in an aqueous solution of ammonia or amine in a large amount, the above-mentioned problems were solved and a polymethylsilsesquioxane powder with excellent free-flowing properties was successfully obtained. (Japanese Unexamined Patent Publication No. 13813/1983). Through this method, new usefulness of polymethylsilsesquioxane as an organic powder was discovered, but it was also necessary to impart qualities such as particle shape as an organic powder, and improvement thereof was desired. [Objective of the Invention] An object of the present invention is to provide a polymethylsilsesquioxane powder having quality characteristics such as uniformity of particle shape and extremely large amount of contact charge, and a method for producing the same. [Structure of the Invention] In order to obtain polymethylsilsesquioxane with such excellent quality characteristics, the present inventor has conducted extensive research, and as a result, methyltrialkoxysilane was hydrolyzed in an aqueous solution of ammonia or amine. The present inventors have discovered that such polymethylsilsesquioxane powder can be obtained by setting appropriate stirring conditions during the condensation reaction, and have now accomplished the invention. That is, the present invention provides (a) methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof, or a mixed solution of methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof and an organic solvent, and (b) ammonia or An aqueous solution of an amine and/or a solution of ammonia or an amine in a mixed solvent of water and an organic solvent is reacted in a two-layer state to form a prepolymer, and the resulting prepolymer is stirred under stirring conditions that do not precipitate until the molecular weight reaches a high molecular weight. The particles obtained by continuous stirring at
30%, and the contact charge amount is -200 to -
A true spherical polymethylsilsesquioxane powder having a density of 2000 μC/g, and (a) methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof, or methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof and an organic solvent. and (b) an aqueous solution of ammonia or amine, and/or a solution of ammonia or amine in a mixed solvent of water and an organic solvent, without substantially mixing the two, with the former in the upper layer, A step of forming a two-layer state with the latter being the lower layer, and a step of forming the above-mentioned (a) and (b) liquids at the interface of both layers while maintaining the upper and lower two-layer state, and precipitating the separated prepolymer. The process of continuing stirring until the upper layer disappears under stirring conditions where the upper layer is suspended in the lower layer, and after the upper layer disappears,
A true spherical polymethyl characterized by comprising the step of continuing stirring under stirring conditions in which the separated prepolymer exists in a suspended state, and increasing the molecular weight to a molecular weight that will not cause coalescence even if the prepolymer is precipitated. This is a method for producing silsesquioxane powder. The raw material methyltrialkoxysilane and its partially hydrolyzed condensate in the present invention may be, for example, methyltrichlorosilane alkoxylated with a suitable alcohol by a known method. This methyltrialkoxysilane is classified into methyltrimethoxysilane, methyltriethoxysilane, methyltriethoxysilane,
Partial hydrolytic condensation of methyltripropoxysilane, methyltributoxysilane, etc., obtained by the presence of a smaller amount of water than the theoretical amount required to completely hydrolyze methyltrialkoxysilane. You may also use objects. Among these methyltrialkoxysilanes, methyltrimethoxysilane is preferably used from the viewpoint of production efficiency. In the present invention, the amount of chlorine atoms present as by-product hydrogen chloride or unreacted methylchlorosilane in the methyltrialkoxysilane obtained by the alkoxylation reaction or its partially hydrolyzed condensate is particularly limited. It's not something you can do. Ammonia or amines in the present invention are
It is a neutralizing agent for the chlorine atoms remaining in methyltrialkoxysilane, and a catalyst for the hydrolysis/condensation reaction of methyltrialkoxysilane. Examples of the amines include monomethylamine, dimethylamine, monoethylamine, diethylamine, and ethylenediamine. As the ammonia or amines used in the present invention, ammonia is advantageous because it has low toxicity, is easy to remove, and is inexpensive, and a commercially available aqueous ammonia solution (concentration 28%) can be used. The amount of ammonia and amines used is the amount sufficient to neutralize the chlorine atoms present in methyltrialkoxysilane or its partially hydrolyzed condensate, plus a catalytic amount. Therefore, it should be kept to the minimum necessary. If the amount of ammonia and amines used is too low,
Hydrolysis of alkoxysilanes and further condensation reactions do not proceed, making it impossible to obtain the desired product. Ammonia or amines are used as an aqueous solution or a mixed solution of water and an organic solvent. Examples of this organic solvent include methanol, ethanol, propyl alcohol, n-butanol,
Alcohols such as iso-butanol; ketones such as dimethyl ketone, methyl ethyl ketone, and acetone; aliphatic hydrocarbon solvents; toluene,
Examples include aromatic hydrocarbon solvents such as xylene. When an aromatic hydrocarbon solvent such as toluene or xylene is used, it is mixed uniformly with methyltrialkoxysilane and/or its partially hydrolyzed condensate. Although the amount of the organic solvent is not particularly limited, it is preferably 20 parts by weight or less based on 100 parts by weight of the total amount of water and organic solvent. The amount of ammonia and amine aqueous solution to be used is at least twice the theoretical amount of water required to hydrolyze the alkoxy groups of methyltrialkoxysilane or its partially hydrolyzed condensate, or the chlorine atoms of unreacted chlorosilane. It is sufficient if there is an amount that includes. In particular, there is no upper limit to the amount of the aqueous solution of the amines mentioned above. However, when the amount of the aqueous solution used increases, it is disadvantageous in terms of the reaction process and the reaction time becomes longer. On the other hand, if the amount used is too small, the hydrolysis reaction will be inhibited by the alcohol by-produced, resulting in a long reaction time, and the object of the present invention having a substantially perfect spherical shape will not be obtained. The hydrolysis/condensation reaction for obtaining substantially spherical polymethylsilsesquioxane powder in the present invention is carried out as follows. That is, in a container equipped with a stirring blade, an aqueous solution of ammonia or amines or a mixture of ammonia or amines in water and an organic solvent (hereinafter referred to as an alkaline solution) and methyltrialkoxysilane and/or its partially hydrated solution are placed. The decomposed condensate and the decomposition condensate are prepared in a two-layered state, with the alkaline solution layer in the lower layer and the methyltrialkoxysilane and/or its partially hydrolyzed condensate layer in the upper layer. Next, the two-layer solution is stirred at an appropriate stirring speed to gradually carry out a hydrolysis/condensation reaction between the methyltrialkoxysilane and the alkaline solution at the interface.
As the reaction progresses, spherical particles (prepolymer) are produced and migrate to the lower alkaline solution layer, and the lower layer turns milky white. The stirring conditions for this reaction vary depending on the shape of the stirring blade, the composition of the alkaline solution, etc., but in order to obtain the target particles that are perfectly spherical and have a narrow particle size distribution, it is recommended to carry out the stirring at a speed of about 2 to 100 rpm. Preferably, it is more preferably 5 to 50 rpm.
If the stirring speed is too high, the methyltrialkoxysilane and/or its partially hydrolyzed condensate before reaction will be drawn into the alkaline solution, and the hydrolysis/condensation reaction will occur rapidly in the alkaline solution, causing particles (precipitates) to form. polymer) will adhere to each other. However, if the stirring speed is too low, the particles (prepolymer) generated by the interfacial reaction will be difficult to disperse in the alkaline solution in the lower layer, and will tend to settle, aggregate, and form lumps. It is preferable to stir with Further, the temperature of this hydrolysis/condensation reaction is not particularly limited, but should be adjusted to be below the boiling point of methyltrialkoxysilane. For example, in the case of methyltrimethoxysilane, the temperature is preferably 50°C or lower. Under the above conditions, the reaction is carried out until the upper methyltrialkoxysilane layer disappears, and stirring is continued to increase the molecular weight of the particles (prepolymer) produced to the extent that they do not coalesce. The time and temperature of this stirring will vary depending on the amount of production, etc.
About 1 to 10 hours is reasonable, and about 50 hours if necessary.
The temperature may be raised to about ℃. Next, the dispersion is extracted through a wire mesh, dehydrated by centrifugal separation or centrifugal filtration, and the resulting paste is heated at 100 to 220°C.
After heating and drying, the powder is crushed using a jet mill, etc., so that at least 95% of the particles are almost perfectly spherical and the amount of contact charge is -200 to -.
A polymethylsilsesquioxane powder with a concentration of 2000 μC/g is obtained. [Effects of the Invention] By the production method of the present invention, truly spherical polymethylsilsesquioxane powder can be obtained for the first time. The true spherical polymethylsilsesquioxane powder obtained in the present invention is used as a filler and additive for synthetic resins, for example, as an agent for imparting slipperiness and mold release properties to synthetic resin films, paper, etc.
In particular, since the particle size distribution is extremely narrow, it is suitable for applications where the thickness of the thin film is strictly controlled, such as in paints that provide the above-mentioned effects. Furthermore, since the amount of contact charge is large, the amount of charge of different powders can be adjusted by adding a small amount. [Examples] Examples of the present invention will be described below. Note that all parts in the examples indicate parts by weight. First, water and an ammonia aqueous solution having a concentration of 28% were stirred in a container at the ratio shown in Table 1 to obtain ammonia aqueous solutions A1 to A4. Note that the numbers indicating the blending amounts in the table represent parts. (same as below.)

[Table] Example 1 Add 4000 parts of ammonia aqueous solution A1 to a 4-necked flask equipped with a thermometer, reflux device, and stirrer,
The mixture was stirred at 100 rpm for 10 minutes to obtain a uniform ammonia aqueous solution. To this ammonia aqueous solution, quickly add 600 parts of methyltrimethoxysilane with a chlorine atom equivalent of 10 ppm while running a stirrer at 5 rpm so as not to mix it into the ammonia aqueous solution. A two-layered ammonia solution layer was formed. Next, the stirring speed of the stirrer was set to 20 rpm to allow the hydrolysis/condensation reaction to proceed at the interface between methyltrimethoxysilane and ammonia aqueous solution while maintaining a two-layer state. As the reaction progresses, the reactant gradually settles to the lower layer, and the lower layer becomes cloudy with the reactant (prepolymer) floating, and the upper methyltrimethoxysilane layer gradually becomes thinner, and the layer becomes cloudy in about 3 hours. It disappeared visually. Furthermore, the temperature was kept at 50 to 60℃, and 3
After stirring for a period of time to increase the molecular weight, the mixture was cooled to 25°C. Next, the precipitated product was filtered through a 100-mesh wire mesh, dehydrated by centrifugation to form a cake, and this cake layer was dried in a dryer at 200°C. This was crushed using a lab jet to obtain a white powder. When the polymethylsilsesquioxane powder thus obtained was observed with an electron microscope, it was found to be almost perfectly spherical with a particle size ratio of 1.0 to 1.2, and an average particle size of about 1.9. It was μm (1.7 to 2.1 μm). Further, the contact charge amount was measured by the blow-off method using a contact charge amount measuring device (manufactured by Toshiba Chemical Co., Ltd.), and the result was -1000 μC/g. Examples 2 to 5 Hydrolysis and condensation reactions of methyltrimethoxysilane were carried out under the same conditions as in Example 1 except for the formulation shown in Table 2 and the stirring speed during the reaction. Sun powder was obtained. Comparative Examples 1 to 3 For comparison with the present invention, as Comparative Example 1, the stirring speed was increased so that the methyltrimethoxysilane layer and the ammonia aqueous solution layer were mixed, and methyltrimethoxysilane was prepared according to the formulation shown in Table 2. Hydrolysis and condensation reactions of silane were carried out. In addition, as Comparative Example 2, the stirring speed was reduced so that the products in the middle of the reaction settled and accumulated at the bottom of the lower layer, and the formulation shown in Table 2 was used to hydrolyze methyltrimethoxysilane.
A condensation reaction was carried out. The properties of the polymethylsilsesquioxane powders of Comparative Examples 1 and 2 obtained by drying and crushing under the same conditions as in the Examples are shown in Table 2. Furthermore, as Comparative Example 3, polymethylsilsesquioxane powder was produced under the conditions and method shown below (method described as Example 1 in Japanese Patent Application Laid-Open No. 13813/1982). First, add 500 parts of water and 28% to a 4-necked flask.
After preparing 50 parts of concentrated ammonia aqueous solution and stirring to make a uniform ammonia aqueous solution (A5),
5ppm in terms of chlorine atoms while stirring at 30rpm
200 parts of methyltrimethoxysilane was gradually added dropwise over about 40 minutes. Next, the reaction system was refluxed at 84°C, and the reaction was continued at this temperature for about 1 hour. After the reaction was completed, it was cooled, and the product precipitated in the flask was collected, dried and crushed under the same conditions as in Examples to obtain polymethylsilsesquioxane powder. The properties of this polymethylsilsesquioxane powder are shown in Table 2.

[Table] *2: Individual particle shape is irregular.
Examples 6 to 8 Aqueous ammonia solution and organic solvent of A2 in the amounts shown in Table 3 were placed in the flask used in Example 1 and heated at 100 r.
After stirring for 10 minutes at Almost spherical polymethylsilsesquioxane powders shown in the table were obtained. Example 9 The reaction was carried out under the same conditions as in Example 6, except that toluene was mixed with methyltrimethoxysilane in advance as an organic solvent, and almost perfectly spherical polymethylsilsesquioxane powder shown in Table 3 was obtained. Ta.

【table】 [Brief explanation of the drawing]

FIG. 1 is an enlarged view of one embodiment of the present invention.

Claims (1)

[Scope of Claims] 1 (a) methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof, or a mixed solution of methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof and an organic solvent; (b) An aqueous solution of ammonia or amine and/or a solution of ammonia or amine in a mixed solvent of water and an organic solvent is reacted in a two-layer state to form a prepolymer, and the resulting prepolymer is stirred without precipitation until it reaches a high molecular weight. The particles are obtained by continuous stirring under the following conditions, and each particle has an independent, almost perfect spherical shape, a particle size distribution of ±30% of the average particle diameter, and a contact charge amount of -200 to -2000 μC/g. True spherical polymethylsilsesquioxane powder. 2 (a) methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof, or a mixed solution of methyltrialkoxysilane and/or a partially hydrolyzed condensate thereof and an organic solvent; (b) an aqueous solution of ammonia or an amine; and/or a solution of ammonia or amine in a mixed solvent of water and an organic solvent without substantially mixing the two;
A step of forming a two-layer state in which the former is the upper layer and the latter is the lower layer, and a step in which both the liquids (a) and (b) are generated and separated at the interface between the two layers while maintaining the upper and lower two-layer state. a step of continuing stirring until the upper layer disappears under stirring conditions such that the polymer does not precipitate and exists in a suspended state in the lower layer; and after the upper layer disappears, continuing stirring under stirring conditions such that the separated prepolymer exists in a suspended state. hand,
A method for producing a truly spherical polymethylsilsesquioxane powder, comprising the step of increasing the molecular weight until the prepolymer has a molecular weight that does not coalesce even if the prepolymer is precipitated.