JPS6136338A - Fine hydrophobic oxide powder and thixotropy imparting agent consisting of said oxide - Google Patents

Abstract

PURPOSE:A thixotropy imparting agent, consisting of fine hydrophobic oxide powder having a specified particle diameter and specific surface area, stably dispersible in a synthetic resin solution, and suitable for thickening and imparting thixotropy. CONSTITUTION:Fine hydrophobic inorganic oxide powder, obtained by hydrophobizing fine metal oxide powder having <=100mmu, preferably 1-50mmu average particle diameter and >=50m<2>/g, preferably 100-500m<2>/g specific surface area, e.g. fumed silica or fumed titania, with a hydrophobizing agent, e.g. a silazane compound, and having >=60vol% critical concentration of methanol causing no wetting in a wetting test with a mixed stream of water with methanol. The resultant fine powder is incorporated in an amount of 0.3-10pts.wt., preferably 0.5-5pts.wt. based on 100pts.wt. liquid resin.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a hydrophobic inorganic oxide fine powder suitable for stably dispersing and imparting increased viscosity and thixotropy to organic liquids, particularly synthetic resin solutions. It provides the body.

Widely in the synthetic resin industry, inorganic oxide fine powders, in particular fumed silica, are used not only as fillers but also as valuable auxiliaries, ie thixotropic agents, for achieving special effects with small additions. The most important effects obtained by adding fumed silica are increasing the viscosity of the synthetic resin liquid system and imparting thixotropy. Among synthetic resin liquid systems, it is particularly effective for polyester resins and epoxy resins, and for molding glass fiber reinforced plastics.
A variety of things such as fishing boats and septic tanks are manufactured using the brush painting method, spray method, etc., but if a certain proportion of fumed silica is added to the resin in advance, the resin will no longer sag even on vertical surfaces. It becomes possible to mold to a thickness of 100 ms. Therefore, it can be said that the purpose of imparting thixotropy by adding Humid 7 Lika is to prevent the resin from sagging on the vertical plane.

[Conventional technology]

Hydrophilic fumed silica has been used as silica as an additive for synthetic resins, but this hydrophilic silica tends to settle over time and separate from the resin liquid, especially when the viscosity of the resin liquid When approval was given to something with a low value, this tendency was extremely problematic for work. For this reason, each manufacturer has taken measures such as shortening the inventory period and storing at low temperatures (which can increase the viscosity and lower the sedimentation rate to some extent), but sufficient results have not necessarily been achieved.

In order to prevent this silica from settling, a method has been adopted in which the surface of the 7 lika particles is made hydrophobic, and in fact, hydrophobized grade products that do not cause particles to settle, such as Nippon Aerosil @4R-
Tough λ is commercially available, but on the other hand, these products tend to lose their neutrality, which is the original purpose of their addition.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a finely divided inorganic oxide, particularly a finely divided silica powder, which has properties suitable for preventing particle sedimentation without losing its chikunthrobic properties.

[Means for solving the problem] The average particle diameter is 100. μ or less, the specific surface ridge is at least jOrrL'/f, and in a wetting test with a water-methanol mixture, the criticality of methanol in the mixture that does not cause gllllt- is t.

When a hydrophobic oxide fine powder having a capacity of 1 or more is added to a synthetic resin liquid, it does not sediment and separate, and can impart sufficient hydrophilicity.

Examples of the hydrophobic inorganic oxide used in the present invention include silica, titania, zirconia, and alumina.

These hydrophobic inorganic oxide fine powders have an average particle size of /0
0 mμ or less, preferably /~so, Bμ. If the average particle size is too large, it will not be suitable for the purpose of increasing the viscosity of the synthetic resin solution and imparting sterility. On the other hand, if the average particle size is too small, it is difficult to manufacture and is not suitable for industrial use.

Furthermore, the hydrophobic inorganic oxide fine powder of the present invention has a specific surface area of at least ! Oyl'/f, preferably 10 o-jo
om'/l.

Inorganic oxide fine powders having a specific surface area of som'71 or less do not have sufficient thickening effect and antiphilicity in organic liquids. On the other hand, ultrafine powder having a specific surface area r 00 m'/f is generally difficult to manufacture.

Furthermore, in a wetting test with a water-methanol mixture, the hydrophobic inorganic oxide fine powder of the present invention has a critical concentration of methanol (hereinafter referred to as M value) in the mixture that does not cause wetting of 60% by volume ( M value to) or more.

A wetness test using a water-methanol mixture indicates hydrophobicity, and is specifically described in the specification of Japanese Patent Publication No. 67-2A≠/ as shown below.

Prepare a mixed solution of methanol and water in which the concentration was varied at an interval of j volume fi%, and add this to a test tube with a volume of 10-m.
I put it in. Next, add the sample powder o, i ~ 0.2,
Shake vigorously and observe after standing to find the limit methanol concentration that does not wet the entire powder, which is expressed as the M value. For example, "M value koO" indicates that a mixed solution of methanol and 20 volumes does not wet the powder, but when the powder has a volume of 2j, a part of the powder begins to wet. In addition, "M value 0//" indicates that water alone does not cause wetting, but wetting occurs at methanol concentration j volume q. Therefore, a high M value indicates high kneading water properties, and in this measurement method, water alone does not wet the water. The degree of complete hydrophobicity in the sense of no wetting can be determined, and if the treatment is non-uniform, the M value will be small or will not appear.In this measurement, wetting occurs when the powder is suspended in the solution. This is observed when the powder becomes cloudy, but in most cases, if there is no moisture, the powder will float near the surface of the solution.On the other hand, due to moisture, the powder will settle, and because it is covered with 7ranol, it will become hydrophilic. It also exhibits viscosity and heterogeneity due to hydrogen bonding.

However, when the surface treatment is made more hydrophobic, that is, when the M value is increased, the above-mentioned thickening properties and thixotropy are lost. This was thought to be natural because the number of hydrogen bonds decreases as the number of hydroxyl groups decreases through the hydrophobization treatment.

However, it has been found that when the M value of the fumed silica force of specific particles is set to 60 or more, not only do they exhibit high hydrophobicity, but also the once-lost thickening properties and titanium tropism are re-expressed. The reason for this is not clear, but it is presumed that because the material is made extremely hydrophobic, a hydrophobic bonding force that is completely different from the original viscosity increase due to hydrogen bonding and thixotropy is at work.

The hydrophobic inorganic oxide fine powder of the present invention as described above is
For example, the average particle size obtained by gas phase oxidation or gas phase hydrolysis of a metal halide such as silicon tetrachloride, silicon tetrafluoride, titanium tetrachloride, zirconium tetrachloride, or aluminum trichloride is 100 mμ or less. And the specific surface area is jO
It is produced by hydrophobicizing metal oxide fine powder of ml/1 or more using a specific method.

Specific examples of the metal oxide fine powder include fumed silica, fumed titania, and fumed alumina.

Examples of the repulsion agent used in the hydrophobization treatment include the following silazane compounds.

[Note]: Me: Methyl group Et; Ethyl group Ph: Phenyl group The amount of the hydrophobizing agent to be used varies depending on the specific surface area of the oxide fine powder to be treated and cannot be uniformly determined, but the approximate value is for the oxide fine powder. Based on this, it is about 2 to 100M. If it is less than 2% by weight, it is difficult to obtain a strong hydrophobization with an M value of 60 or more, and on the other hand, even if it is used in an amount of 100% by weight or more, the commensurate effect cannot be achieved.

The method of hydrophobizing the oxide fine powder is not particularly limited as long as the aqueous groups on the surface of the oxide fine particles and the silazane compound react uniformly, but for example, the method of uniformly hydrophobizing the oxide fine powder can be used. In order to do this, it is desirable to keep the powder in a fluid state, evaporate the silazane compound as a hydrophobizing agent, and treat it in a gas phase at a temperature above its boiling point and below 3 JO°C. Conventionally, the main hydrophobization method has been to dilute a silane coupling agent or the like with an alcohol solvent, etc., and then drop or spray the solution. Local unevenness existed, causing problems in terms of dispersion of particles, etc. Also, with this method, the M value is 6.
It is difficult to significantly improve the strength of hydrophobization as above Q.

When treating with a silazane compound, the strength of hydrophobization can be increased to M if the reaction is carried out at 200°C for about 1 minute without using a particular catalyst.
Since the value reaches 608 degrees, it is necessary to use a catalyst! I! However, in order to quickly complete the reaction at a lower temperature, known catalysts such as aliphatic amines may be used. Furthermore, when introducing the vapor of the silazane compound, it may be diluted with an inert gas such as Nts air. It is desirable that the time required for this reaction is 75 minutes or more, but since the hydrophobicity of the powder will not be further improved even if the time is ≠ or more, a time of 6 minutes to f hours is usually sufficient.

In addition, in order to keep the oxide fine powder in a fluidized state, a fluidized bed, stirring tank, pipeline mixer, etc. can be used for the treatment reaction.
Although this is carried out by passing a gas containing a silazane compound, it is important to improve the contact efficiency of the surrounding air in order to avoid non-uniformity of the treatment. Also, returning the gas from one reaction to the system in a liquid state through total reflux corresponds to the above-mentioned case of dropping with droplets, and since locally non-uniform areas occur, it is necessary to carry out one-bath or recycling in the gas phase as much as possible. Good method to use.

The oxide powder treated in this way adsorbs ammonia produced by the reaction, so it shows basicity and has a strong ammonia odor, so it is odorless and neutral without changing the degree of hydration. You can get the following.

[Operation and effect of the invention]

The hydrophobic oxide fine powder of the present invention is stably dispersed in a thermosetting liquid resin, and is suitable for thickening and imparting properties, and is an unsaturated polyester suitable for hand lay-up, tin lay-up, filament winding, or gel coating. Ideal as a tactile agent for resins or epoxy resins.

The amount of oxide fine powder used is usually 0.3 to 1077 parts by weight, preferably 0.1 to 1077 parts by weight, per 100 parts by weight of liquid resin. This is Okibe.

The hydrophobic oxide fine powder of the present invention is also useful as a modifying agent for paints, inks, adhesives, synthetic rubber, etc., and it can also be used as a variety of water-repellent coating agents and powders that take advantage of its strong hydrophobicity. It can also be used for the purpose of improving body fluidity and preventing caking.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example/ Gas blowing pipe and gas discharge pipe (both kept at 200°C),
In a glass separable flask with an internal volume of 1 liter equipped with a stirrer and a thermometer, the average particle diameter was 4 mμ and the specific surface area was 200.
Humid silica (manufactured by Nippon Aerosil Co., Ltd. #COOO) having m'/f, 252 was added to J (777'C with stirring, and hexamethyldisilazane gas f1.f).
/hr. After reacting for 2 hours, the temperature was lowered to 200°C and the atmosphere was purged with nitrogen gas for 1. The process was continued for r minutes and the powder was taken out.

The obtained powder showed extremely high hydrophobicity with an M value of 6j in a wet test with a water-methanol mixture. The M value of the fumed silica before the reaction was negative (-), meaning that it was wet with water.

Example The same procedure as in Example 1 was carried out except that the reaction temperature f was changed to 200°C and the reaction time was shortened to 30 minutes.

The powder obtained as a result showed extremely high hydrophobicity with an M value of 60.

Example 3 The hydrophobic silica obtained in Examples/and λ was added to a resin, and other attractive effects were investigated.

Styrene solution of unsaturated polyester (manufactured by Dainippon Ink & Chemicals ■, trademark Polylye) FG-IO≠) (viscosity If2.
0 voids) 100 (parts by weight), the hydrophobicity and hydrophilicity obtained in Examples/and λ were measured, and the results were
Shown in the table.

In addition, in order to examine the sedimentation properties of the dispersed solid particles, a glass measuring cylinder (height: approximately s o Om) containing the resin slurry
) VC fractionation and investigation of sedimentation state of particles after λ weeks,
The results are also shown in Table 1.

The viscosity was measured using a B-type rotational viscometer manufactured by Tokyo Keiki Co., Ltd., and the heterogeneity was expressed as the Chikuntrobei index (TI index). The thixotropic index is the viscosity ratio measured by changing the rotational speed of the rotor using a rotational viscometer, and is as follows.

For comparison, in place of the hydrophobic curing force of the present application, untreated hummed silica (manufactured by Nippon Anilsil@, trademark Aerosil #coOO) and commercially available hydrophobic fumed silica were used for 'fc' results. It was shown to.

Claims (2)

[Claims] (1) The average particle diameter is 100 mμ or less, the specific surface area is at least 50 m^2/g, and the critical concentration of methanol in the mixture that does not cause wetting in a wetting test with a water-methanol mixture is 60% by volume. A hydrophobic oxide fine powder characterized by the above. (2) The average particle size is 100 mμ or less, the specific surface area is at least 50 m^2/g, and the critical concentration of methanol in the mixture that does not cause wetting in a wetting test with a water-methanol mixture is 60% by volume. A thixotropy imparting agent for a thermosetting liquid resin comprising the above hydrophobic oxide fine powder.