JPH0830150B2 - Polyorganosilsesquioxane fine particles and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyorganosilsesquioxane having a core portion composed of a polymethylsilsesquioxane unit and a surface layer portion composed of a perfluoroalkylsilsesquioxane unit. The present invention relates to fine particles and a method for producing the same.

[Problems to be Solved by Prior Art and Invention]

Conventionally, fine powders composed of polymethylsilsesquioxane units have been known (Japanese Patent Publication Nos. 40-17917 and 56-398).
08, Japanese Patent Publication No. 2-22767, JP-A-63-77940, 63-
295637), which has good fluidity and water repellency and excellent compatibility with organic resins, and is therefore useful as fillers for organic resins, water repellents, moisture absorption inhibitors for powder digestive agents, cosmetic additives, etc. It is something.

It is also known to treat the surface of such polymethylsilsesquioxane fine powder with an organic functional silane or the like to impart various functions (Japanese Patent Laid-Open No. 63-101857).
JP-A-1-268609). In this case, as these known surface treatment methods, polymethylsilsesquioxane fine powder is added to the surface treatment agent to be adsorbed, and a mixture of the polymethylsilsesquioxane fine powder and the surface treatment agent is pulverized. While treating, a method of treating by adding polymethylsilsesquioxane fine particles to an organic solvent bath of a surface treating agent, after dispersing polymethylsilsesquioxane fine particles in an organic solvent solution, a surface treating agent A method of adding and adsorbing is added, whereby a functional functional group is fixed to the surface of the polymethylsilsesquioxane fine powder.

However, in these methods, a surface treating agent is simply allowed to act on the inert surface of the polymethylsilsesquioxane fine powder, and the reactive group in the surface treating agent, such as an alkoxy group, is applied to the surface of the polymethylsilsesquioxane fine powder. Although the silyl group is adsorbed, a chemical bond does not easily occur between the two. Therefore,
Since the surface treatment agent remains adsorbed on the polymethylsilsesquioxane fine powder in this way, various deterioration conditions such as extraction conditions by contact with organic solvents, chemicals, organic polymers and various Under a frictional condition due to contact with the solid, the surface-treated layer may fall off.

On the other hand, as a solution to the problem of the surface treatment layer falling off, it has been proposed to use a polyorganosilsesquioxane fine powder having a silicon-bonded hydrocarbon of 6 or less carbon atoms. Kaihei 1-217039). However, in this proposal, although the loss of the organic functional group is essentially impossible, as the number of substituents bonded to the silicon atom increases, the cross-linking density in the fine powder decreases, so the fine powder There is a problem that the strength of the body is reduced.

The present invention has been made in view of the above circumstances, in which the surface layer part is chemically bonded to the polymethylsilsesquioxane fine particle core part, the surface part is less likely to fall off, and the strength is high, and the low energy surface has a fluidity. It is an object of the present invention to provide polyorganosilsesquioxane fine particles having excellent dispersibility and durability, and a method for producing the same.

[Means and Actions for Solving the Problems]

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to obtain the particle which has the said objective and was especially excellent in particle characteristics, and also has the low energy surface which the perfluoroalkyl group has excellent, methyltrialkoxysilane or its partial hydrolysis. Hydrolysis of the decomposed condensate in an aqueous solution of alcal such as ammonia, amines or alkali metal hydroxides to form a spherical polymethylsilsesquioxane microparticles core, in which the surface activity remains By immediately adding perfluoroalkyltrialkoxysilane and performing hydrolytic condensation, it was found that a surface layer portion composed of perfluoroalkylsilsesquioxane units chemically bonded to the above-mentioned core portion was formed. The fine particles obtained in step 1 have a polymethylsilsesquioxane unit at the core and a permeate at the surface. It is composed of a loroalkylsilsesquioxane unit, and as described above, the core part and the surface part are chemically bonded, so that the perfluoroalkylsilylyl group in the surface part is less likely to fall off from the core part. The properties of the perfluoroalkylsilsesquioxane in the parts are effectively exhibited, and it has excellent low energy surface performance, and has excellent effects in water repellency, oil repellency, lubricity, non-adhesiveness, dispersibility, fluidity, etc. The present invention has been accomplished by finding that the durability is high.

Therefore, the present invention is a polyorganosilsesquioxane fine particle having a core portion composed of a polymethylsilsesquioxane unit and a surface layer portion composed of a perfluoroalkylsilsesquioxane unit, and a methyltrialkoxysilane or a portion thereof. After hydrolyzing the hydrolyzed condensate in an aqueous alkaline solution to form a core consisting of polymethylsilsesquioxane units, perfluoroalkyltrialkoxysilane is added to the aqueous medium in which the core is dispersed, to add water. Disclosed is a method for producing polyorganosilsesquioxane fine particles, which comprises performing decomposition condensation to form a surface layer portion comprising a perfluoroalkylsilsesquioxane unit on the core portion.

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

Polyorganosilsesquioxane fine particles of the present invention,
As described above, the core portion is made of polymethylsilsesquioxane unit (CH ₃ SiO _3/2 unit) and the surface layer portion is made of perfluoroalkylsilsesquioxane unit.
In this case, as the perfluoroalkylsilsesquioxane unit, R ^f CH _Z CH _Z SiO _3/2 (R ^f is a perfluoroalkyl group, particularly a perfluoroalkyl group having 4 to 10 carbon atoms is preferable. (Preferred) units are preferred.

The polyorganosilsesquioxane fine particles may be substantially spherical, but of course, they may have a shape such as an ellipsoid. The average particle size is usually 0.05 ~
20 μm.

When obtaining such polyorganosilsesquioxane fine particles, first, as a first step, a core portion of the polymethylsilsesquioxane fine particles is formed. As a method of forming this,
Although a known method for producing fine particles of polymethylsilsesquioxane can be adopted, a method of hydrolyzing methyltrialkoxysilane or a partial hydrolysis-condensation product thereof in an alcal aqueous solution is particularly adopted.

In this case, examples of the raw material methyltrialkoxysilane and its partial hydrolysis-condensation product include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane and the like, and partial hydrolysis-condensation products thereof. However, among them, it is preferable to use methyltrimethoxysilane or a partial hydrolysis-condensation product thereof in view of easy availability and production efficiency.

On the other hand, the alkali acts as a catalyst for the hydrolysis and condensation reaction of the alkoxysilyl group, which includes amines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monoethanolamine, diethanolamine and ethylenediamine, ammonia and water. Examples thereof include alkali metal hydroxides such as sodium oxide and potassium hydroxide. The amount of these catalysts should be at least an amount sufficient to neutralize the trace amount of ≡SiCl or hydrogen chloride remaining in the raw material methyltrialkoxysilane, and since it must be finally removed, the minimum required amount is required. It is preferably used in a limited amount, but if the amount is too small, gelation is likely to occur, and the hydrolysis-condensation reaction of the alkoxysilyl group is difficult to proceed, whereby the intended product may not be obtained in some cases. For this reason,
The amount of alkali is appropriately selected from the above points, and for example, in the case of ammonia, it is preferably in the range of 0.1 to 1.5 mol, and in the case of potassium hydroxide, it is preferably in the range of 0.01 to 0.1 mol. The theoretical amount of water in the alkaline aqueous solution is 2 mol of water per 1 mol of the alkoxysilyl group of the raw material methyltrialkoxysilane, but the alcohol produced by the hydrolysis reaction is the hydrolytic condensation reaction of the alkoxysilyl group. Because it inhibits
It is preferable to use a large excess of water within a range that does not adversely affect the subsequent steps.

The hydrolysis / condensation reaction for forming the core of the polymethylsilsesquioxane fine particles is carried out by dropping methyltrialkoxysilane or its partial hydrolysis / condensation product into the above alkaline aqueous solution with stirring and further aging reaction with stirring. In this case, the dropping time is usually 0.5 to 5 hours, especially 1 to 3 hours, and the aging time after dropping is usually 0.5 to 3 hours, especially 1 hour.
~ 2 hours. Further, the reaction temperature, particularly the temperature during aging, is preferably -10 to 50 ° C, more preferably 0 to 30 ° C. If the aging time is too long, or the temperature during aging is too high, aging excessively eliminates the active silanol group from the surface of the fine particle core of the obtained polymethylsilsesquioxane. In some cases, the surface layer to be formed cannot chemically bond with this core.

Next, in the present invention, after the polymethylsilsesquioxane fine particle core is formed in the first step as described above, the second step is followed by the hydrolytic condensation reaction of the perfluoroalkyltrialkoxysilane. The surface layer of perfluoroalkylsilsesquioxane is formed on the surface of the core of the fine particles. In this case, the formation of this surface layer portion requires that the fine particle core portion and the surface layer portion are firmly bonded to each other by a siloxane bond. Therefore, before the active silanol groups on the surface of the fine particle core portion disappear. It is necessary to carry out the second stage reaction. Therefore, the surface layer forming reaction in the second step is in the state of fine particle nuclei, and the perfluoroalkyltrialkoxysilane is stirred in the above alkaline aqueous solution dispersion of polymethylsilsesquioxane in which active silanol is present. It is desirable to drop the solution and carry out a hydrolysis condensation reaction.

Examples of the perfluoroalkyltrialkoxysilane used include R ^f CH ₂ CH ₂ Si (OR) ₃ (wherein R ^f represents a perfluoroalkyl group, R represents an alkyl group, and particularly R ^f has 4 to 4 carbon atoms).
Preferably, 10 is a perfluoroalkyl group and R is a methyl group or an ethyl group. ) Is effectively used.
Such perfluoroalkyltrialkoxysilanes include CF ₃ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OC ₂ H ₅ ). ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OC ₂ H ₅ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OC ₂ H ₅ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ C ₂ H ₄ Si (OC ₂ H ₅ ) ₃ , Etc. are illustrated.

The amount of perfluoroalkyltrialkoxysilane used depends on the intended use of the final product, but the CH ₃ SiO
The weight ratio of the perfluoroalkylsilsesquioxane unit to the _3/2 unit is preferably in the range of 3: 1 to 50: 1, and a ratio exceeding this may cause the strength of the obtained particles to become weak. , And at lower ratios,
The low energy performance due to the perfluoroalkyl group may not be sufficiently exhibited.

When the perfluoroalkyltrialkoxysilane is added dropwise to the aqueous dispersion of polymethylsilsesquioxane in an aqueous alkaline solution, the perfluoroalkyltrialkoxysilane may be added as it is, but for the purpose of providing more uniformity, It is preferable that the perfluoroalkyltrialkoxysilane is dissolved in a solvent that is soluble in both the fluoroalkyltrialkoxysilane and water, and this is added dropwise. Examples of such a solvent include methanol, ethanol, isopropanol, acetone, and methyl ethyl ketone.

The dropping time of the perfluoroalkyltrialkoxysilane is usually 5 minutes to 5 hours, especially 15 minutes to 3 hours, and the dropping temperature can be -10 to 50 ° C, especially 0 to 30 ° C.
After dropping, the target product can be obtained by stirring for 5 to 10 hours, but in order to obtain high-performance particles with lower energy, it is preferable to complete the hydrolysis condensation reaction as much as possible. In order to drop 70 to 100 ℃
It is preferable to perform heating in the temperature range of 1 to 10 hours. Further, it is effective to remove the by-produced alcohols or the diluting solvent at the time of dropping the perfluoroalkyltrialkoxysilane to the outside of the system in the heat aging step in order to complete the reaction.

When the reaction is carried out as described above, as the reaction proceeds, the produced polyorganosilsesquioxane fine particles are precipitated from the reaction solution and become in a state of floating on the surface,
This is collected, washed with water, and if necessary, washed with an organic solvent such as methanol, ethanol or acetone, and dried to obtain the desired polyorganosilsesquioxane fine particles. In this case, since the surface of the fine particles is covered with a perfluoroalkyl group, there is almost no cohesiveness, and thus primary particles with less coagulation can be obtained even in the stage after drying, but if necessary, jet Crushing can also be performed using a mill grinder or the like.

〔The invention's effect〕

As described above, according to the method of the present invention, a polyorganosilsesquioxane having a double structure of a core portion containing a methylpolysilsesquioxane unit and a surface layer portion containing a perfluoroalkylsilsesquioxane unit is provided. The fine particles can be efficiently obtained by a simple operation, and since the fine particles of the fine particles are strongly bonded to each other by the chemical bond, the surface layer is prevented from falling off and has excellent durability. It can withstand extraction conditions by dyeing with an organic substance or abrasion conditions by contact with a solid substance. Further, the fine particles having a low energy surface are excellent in water repellency, oil repellency, lubricity, non-adhesiveness, dispersibility and fluidity.

Therefore, the polyorganosilsesquioxane fine particles of the present invention are non-adhesive coating agents (for example, coating agents for heat-sensitive recording films, magnetic tape backing agents) prepared by combining with water / oil repellent agents and binder resins. It is useful as a coating agent, antifouling paint, anti-paper sticking paint, paper coating agent, car coat agent, etc.), cosmetic material, polish additive, electrophotographic negatively charged toner additive, etc. is there.

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.

[Example 1] 550 g of water and 50% of 28% ammonia water were placed in a glass reactor 1 equipped with a stirring blade, a thermometer, a dropping funnel, and a reflux condenser.
g and were charged, and the temperature was maintained at 20 ° C. while stirring at a rotation speed of 150 rpm. 136g of methyltrimethoxysilane was added dropwise to this through a dropping funnel for one and a half hours,
After further aging for 1 hour, fine particles of polymethylsilsesquioxane were obtained. Then immediately 28.4 g of CF ₃ (CF ₂ ) ₇ CH ₂ C
A mixture of H ₂ Si (OCH ₃ ) and 40 g of methanol was added dropwise through the dropping funnel over 30 minutes, followed by aging for 1 hour. During this period, the rotation speed was maintained at 150 rpm and the temperature was maintained at 20 ° C. Next, while maintaining the stirring rotation speed at 150 rpm, heating was performed using an oil bath, methanol was distilled off through an ester adapter until the internal temperature reached 90 ° C., and an aging reaction was performed at 90 ° C. for 3 hours. The generated fine particles were separated in the form of floating in the upper layer of the aqueous solution, so they were collected, washed with ion-exchanged water 3 times, with methanol twice, and finally with acetone once, and then air-dried to give white fine particles 86.4 got g.

When these fine particles were observed with an electron microscope, it was confirmed that most of the particles had an independent spherical shape. In addition, a particle size analyzer (Coulter Electronics INC. Co
The average particle size was 2.1 μm when the particle size distribution was examined using an ulter counter model TA-II). Furthermore, it was confirmed by FTIR analysis that the surface layer was a perfluoroalkylsilyl group.

The fine particles were tabletted using a tablet molding machine for preparing an infrared absorption spectrum sample, and ion-exchanged water droplets were placed on this surface to measure the contact angle, and a value of 148 ° was obtained. Also, in a 25 ml transparent glass bottle, 15 g of oleic acid and 1 g of fine particles were placed, and after vigorous shaking, the mixture was left standing, and the fine particles were completely phase-separated from oleic acid and floated on the upper layer of oleic acid. It was confirmed that the particles have excellent oil repellency.

[Examples 2 to 4] Using the raw materials shown in Table 1, the same procedure as in Example 1 was repeated to prepare a polyorgano having a polymethylsilsesquioxane core and a perfluoroalkylsilsesquioxane surface layer. Fine particles of silsesquioxane were obtained.

Further, the contact angle of the obtained fine particles with water and the wettability with oleic acid were measured in the same manner as in Example 1. Table of results
It is shown in FIG.

[Comparative example]

100 g of polymethylsilsesquioxane fine particles obtained according to the description of Japanese Patent Publication No. 2-22767, under high speed stirring
A mixture of 30 g of CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH ₃ ) _{3 and} 30 g of methanol was added dropwise, and the mixture was heated to 90 ° C. with stirring to remove methanol to obtain fine particles treated with perfluoroalkylsilane. It was

With respect to the obtained fine particles and the fine particles obtained by washing with acetone and drying, the contact angle with water and the wettability with oleic acid were examined in the same manner as in Example 1. The results are shown in Table-2.
Shown in

Claims (2)

[Claims] 1. Polyorganosilsesquioxane fine particles having a core portion composed of a polymethylsilsesquioxane unit and a surface layer portion composed of a perfluoroalkylsilsesquioxane unit. 2. An aqueous medium in which a methyltrialkoxysilane or a partial hydrolysis-condensation product thereof is hydrolyzed in an alkaline aqueous solution to form a core comprising polymethylsilsesquioxane units, and then the core is dispersed. Hydrocondensation is performed by adding perfluoroalkyltrialkoxysilane to the inside of the polyorganosilsesquioxane fine particles, which is characterized in that a surface layer portion comprising a perfluoroalkylsilsesquioxane unit is formed on the core portion. Manufacturing method.