JPS59172553A - Water-repellent silica dispersion and production thereof - Google Patents

Abstract

PURPOSE:To produce water-repellent silica uniformly dispersed in an org. solvent, by reacting fine silica powder with a methylhydrogenpolysiloxane in a dispersion medium. CONSTITUTION:Fine silica powder (e.g. kaolin) having silanol groups on its surface is dispersed in an org. solvent (e.g. isopropanol) having an azeotropic point with water in the range of 60-140 deg.C under atmospheric pressure. 0.2- 5wt% water and a catalyst (e.g. zinc octoate) are added to the dispersion. The resulting dispersion is heated to 60 deg.C or higher in a nitrogen gas atmosphere. A methylhydrogenpolysiloxane having a viscosity of 20-40cst is added thereto while stirring to effect crosslinking and polymn. The above org. solvent or other high-boiling org. solvent (e.g. butyl cellosolve) is added to the reaction product to give a dispersion having a solid concn. of 5-50wt%. USE:Anti-settling agent for pigment, delustering agent, grease thickener, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dispersion of water-repellent silicas, particularly water-repellent silicas uniformly dispersed in an organic solvent, and a method for producing the same.

Conventionally, several methods have been proposed for converting silanol groups on the surface of silicas to make them water-repellent silicas.

For example, the product name "estadil" (US Patent No. 265714), which has an aliphatic alcohol bonded to the silanol group, is
No. 9) is a typical example.

In addition to "estadyl", we also use surfactants, amines, polymer substances, organochlorosilanes, aromatic silanes, etc.
There are many water-repellent silicas, such as those in which the hydrophilicity of the silanol group is converted to hydrophobicity by -nol or the like.

However, all of the above-mentioned water-repellent silicas are in powder form and have certain drawbacks in use.

That is, the powder scatters during use, making it difficult to work, or when the silica is dispersed in a solvent, the dispersibility is poor.

In addition, in the conventional method for producing water-repellent silicas, the silica is processed and handled almost as a powder, resulting in large-sized equipment and a processing temperature exceeding 250° C., which poses various difficulties in the manufacturing process. Furthermore, it has been difficult to produce a uniformly dispersed product using conventional methods.

The present inventors have completed the present invention as a result of intensive research in order to obtain water-repellent silica in a uniformly dispersed state without the above-mentioned drawbacks.

That is, the present invention provides a water-repellent silica dispersion obtained by subjecting fine silica powder and methyl/1 hydrodiene polysiloxane to a crosslinking polymerization reaction in a dispersion medium, and a water-repellent silica dispersion obtained by dispersing fine silica powder in an organic solvent. 60°CJ21. Provided is a method for producing a water-repellent silica dispersion, characterized in that methylhydrodiene polysiloxane is added at the above temperature to cause a crosslinking polymerization reaction, and the reaction product is dispersed in the organic solvent or another organic solvent. .

Examples of the silicas to be treated in the present invention include those having silanol groups on the surface, such as silicon dioxide, calcium silicate, kaolin, talc, mica beds, shirasu balloons, and glass balloons. Preferred are silicon dioxide, calcium silicate, and kaolin-talc. Such silicas include alkaline-neutral and acidic silicas, and any of these may be used. Preferably, alkaline materials are easy to process.

Methylhydrodiene polysiloxane used as water repellent has the following structural formula: viscosity is 20~25°C
4 Q cst, and when the viscosity is high, dilute with toluene etc. before use. The amount used is 5 to 30% by weight based on the object to be treated.
It is sufficient that the water repellency is within this range, but it is not limited to this range, and can be adjusted according to a desired water repellency value.

Examples of organic solvents used in the production method of the present invention include alcohols,
Any hydrocarbons, ethers, etc. may be used. Preferably, it has an azeotropic point with water at a temperature of about 60 to 140°C under normal pressure, such as - alcohols, such as methanol, ethanol, impropatol, etc.; hydrocarbons, For example, benzene, toluene,
Mixed xylenes and the like; or ethers such as methyl cellosolve.

The treatment temperature may be 60° C. or higher, and the reaction is usually carried out under azeotropic conditions of an organic solvent and water.

Normally, fine silica powder has water absorbed by moisture in the air. If the adsorbed water content is less than 2% by weight, the silanol groups are activated in order to facilitate temperature treatment and to activate the water-solvent azeotropic phenomenon in the reaction system. In order to shorten the treatment reaction time, the amount of water present in the reaction system is 0.2% or more of the total weight, preferably 0.5 to 3%.
．． 0% and should not exceed 5%. If it exceeds 5% by weight, the viscosity will increase and productivity will decrease.

A catalyst may be added to improve the efficiency of the reaction.

Suitable catalysts include tin organic salts such as dibutyltin laurate; lead organic salts such as lead octoate; and zinc organic salts such as zinc octoate.

In the reaction, fine silica powder is heated and stirred in an organic solvent, water and a catalyst are added as appropriate, and methylhydrodiene polysiloxane is gradually added dropwise. Hydrogen gas is generated by the reaction and is released outside the system by a nitrogen gas stream.

In the dispersion of the present invention, the solvent used in the reaction can be easily replaced with another solvent having a high boiling point or a solvent suitable for the purpose of use. Such other solvents include mineral oils, such as naphthenic mineral oil, paraffinic mineral oil, chlorinated naphthenic mineral oil, chlorinated paraffinic mineral oil, etc.; cellosolves, such as butyl cellosolve; polyether polyols, such as ethylene. Examples include glycol.

The solid content of the dispersion of the present invention is 5 to 50% by weight, preferably 20 to 40% by weight, based on the total weight, and the solvent is removed as necessary to obtain such a solid content concentration.

The dispersion of the present invention can be obtained in the form of a uniform dispersion in a solvent, and unlike conventionally known powders, there is no need to prevent scattering, and the work is easy. Moreover, since it is already uniformly dispersed in the solvent, there is no need to consider dispersibility.

Therefore, since it can be used as a solution, it can be used in various ways. For example, in paints, it is used as a pigment anti-settling agent, as a gloss remover, and as a water resistance improver for paint films.In ink, it is used as a gloss remover, as a water resistance improver, and as a color tone clarifying agent, and as a grease thickener and as a water resistance improver. The usability is significantly improved as a heat resistance improver, as a paper rise improver for electrostatic recording paper, and as a raw material for antifoaming agents.

On the other hand, in terms of manufacturing, the method of the present invention not only avoids increasing the size of the equipment since all of the water repellent treatment is carried out in a solution system, but also the water repellent treatment itself is more uniform than in a dry system. Moreover, since the reaction product is obtained in a uniformly dispersed form in the solvent, it has the characteristics that it can be easily applied to other uses.

Next, the present invention will be explained in detail using examples.

In the examples, % represents weight %.

Examples 1 to 5 10ooy of toluene was put into a glass separable flask with a capacity of 21 and equipped with a gas blowing tube, a dropping funnel, a thermometer, a cooling tube, and a stirrer, and while stirring, the adsorbed water was 6
．． 3% wet silicon dioxide (manufactured by Shionogi & Co., Ltd., part name "Carplex #67", apparent specific gravity 0.16)
~0.19) 9! M' was added and dispersed in toluene. Next, zinc octoate o, 2y was added as a catalyst and heated to around 85°C using a mantle heater in a nitrogen stream. After the internal temperature was stabilized, methylhydrodiene polysiloxane (toμ Manufactured by Silicone Co., Ltd. Part name 5I (-1107, viscosity 25°C
30 cst) and 4.8 y were added dropwise at a dropping rate of 1 hour.

Thereafter, it was aged for 2 hours at around 93°C, which is the boiling point of this system.

Use the same method as above to connect “Carplex #67” and “S I
-1-1,107j was used in various amounts as shown in Table 1.

The obtained reaction product was dried at 110° C. for 1 hour to form a powder, and Md1) was measured using the following method. The results are shown in Table 1.

(1) Method for measuring M value: The powdered product was ground in a mortar until no lumps were felt on the tip of the finger, and the sample was used as a measurement sample. Take 53 me of a water/methanol mixture into a 100 me separatory funnel, gently float 0.1 y of the sample on the surface of this liquid with a spaticle, and place it in a shaker (Iwaki Lab Shaker ■-5 type 250-300 r).
pm) and shaken for 5 minutes.

The degree of wetting and dispersion after shaking was observed with the naked eye, and the methanol volume value of the water/methanol mixture that did not wet or disperse at all was determined as M.
value.

Table 1 Examples 6 to 9 In the same manner as in Example 1, wet silicon dioxide 95y having different pH and specific gravity was reacted with rSI (-1107J4.8), and the M value was measured.

The results are shown in Table-2.

Table 2 Example 10 Powders treated in the same manner as in Example 1 using calcium silicate (Tokuyama Soda Co., Ltd., Solex) instead of silicon dioxide and Impropatool as the solvent were as follows: As a result of vigorous shaking in a two-phase solution of toluene and water, it was suspended only in the toluene phase and exhibited water repellency.

Example 11 Similar to Example 10, glass balloons (Emerlin & Cumming Co. - ECCO5-5HERES) were used instead of silicon dioxide.
IG-101), Shirasu balloon (resuscitation cement (
Kaolin (South Eastern Co., Ltd.'s Crown Clay), talc (Nippon Talc Co., Ltd.'s Talc SW), and mica powder (Yamaguchi Mica Co., Ltd.: Mica powder A-41)
) When the powders were shaken in a two-phase solution of toluene and water, they were suspended only in the toluene phase and exhibited water repellency.

Procedural amendment (voluntary) May 11, 1980 Commissioner of the Japan Patent Office 1 Display of the case 1988 Patent Application No. 47582 2 Name of the invention Water-repellent silica dispersion and its manufacturing method 3 Case of the person making the amendment Relationship with the patent applicant (and one other person) 4. Date of the agent's 5 amendment order (voluntary) 7. Contents of the amendment (1) Page 5 of the specification, lines 12 to 16, ``If the adsorbed water...・・・・・・−・−・−・−・・・・ The amount of water is
The statement has been corrected as follows: ``If the adsorbed moisture is less than 2% by weight, silanol groups may be added to facilitate multi-temperature control due to the water-solvent azeotropic phenomenon in the reaction system. Water is preferably added to the reaction system in order to activate it and shorten the processing reaction time, and the amount of water present in the reaction system is

Claims (1)

[Claims] 1. A water-repellent silica dispersion obtained by subjecting fine silica powder and methylhydrodiene polysiloxane to a crosslinking polymerization reaction in a dispersion medium. 2. Silica fine powder contains silicon dioxide, calcium silicate,
2. The dispersion according to claim 1, which is selected from the group consisting of kaolin and talc. 3. Disperse fine silica powder in an organic solvent, add methylhydrodiene polysiloxane at a temperature of 60°C or higher to cause a crosslinking polymerization reaction in the presence of water, and transfer the reaction product to the organic solvent or other organic solvent. A method for producing a water-repellent silica dispersion, which comprises dispersing it in a solvent. 4. Silica fine powder contains silicon dioxide, calcium silicate,
4. The method according to claim 3, wherein the method is selected from the group consisting of kaolin-talc. 5. The manufacturing method according to item 3, wherein the amount of water is up to 5% by weight of the total weight. 6. The method according to item 3, wherein the organic solvent is inpropatol or toluene.