JP2003342017A - Fine anhydrous silica powder and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fine anhydrous silica powder having a large contact angle and obtained by the hydrolysis of an alkoxysilane and its producing method. <P>SOLUTION: The fine anhydrous silica powder is obtained by adding a volatile alkali substance to a solution of an acryl-silicone resin denoted by formula (1) (wherein x is an integer of 5-300; R<SP>1</SP>and R<SP>2</SP>are each methyl, hydrogen, an acetic acid group, or an acetic ester group; R<SP>3</SP>is a straight-chain or branched alkyl group or hydroxyl; and l, m, and n are each a molar ratio) and adding at least one alkoxysilane denoted by formula (2): Si(OR<SP>4</SP>)<SB>4</SB>to the solution to hydrolyze the alkoxysilane. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-repellent silica fine particle which can be used as a water-repellent agent effective for preventing water drops, ice and frost from adhering to paint, plastic, glass, metal, paper, cloth and the like. The present invention relates to a manufacturing method thereof.

[0002]

2. Description of the Related Art For the purpose of preventing water droplets from adhering to painted surfaces of automobiles, home appliances, buildings, window glass of automobiles and buildings, wood, paper, road signs, shop signs, rain gear, clothing, etc. Synthetic wax such as dimethylpolysiloxane water repellent, fluororesin, natural wax such as carnauba wax, polyethylene wax, etc. is applied, but water droplets left on the surface leave stains on the surface when dried and damage the appearance, such as mold. There is a problem of generating the above microorganisms.

[0003]

The present invention has been made in view of such circumstances. The particle size of silica can be controlled by hydrolyzing an alkoxysilane in a solvent having different polarities. The particle size of silica obtained by the coexistence of a water-soluble resin is small, but the contact angle with water is small. The present invention has found water-repellent silica fine particles having a large contact angle obtained by hydrolysis of alkoxysilane and a method for producing the same, and has completed the present invention.

[0004]

The present inventor has conducted various studies to develop a water repellent having a large contact angle with water. As a result, the alkoxysilane represented by the general formula (2) or the general formula One or more alkoxysilanes or alkyldiones in which 5 to 80% by weight of the alkoxysilanes (2) are replaced by the alkoxysilanes or alkyldisilazanes represented by the general formula (3) or (4). The water-repellent silica fine particles obtained by hydrolyzing silazane in the presence of an acrylic silicone resin represented by the general formula (1) and a volatile alkaline substance can achieve the object. Heading out, the present invention has been completed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as an example of the acrylic silicone resin represented by the general formula (1), a copolymer of a polymerizable unsaturated fatty acid of azo group-containing dimethylpolysiloxane and a (meth) acrylic acid ester Is mentioned. The method for producing the copolymer is, for example,

[Chemical 3] There is.

As an example of the monomer constituting the polymer used in the present invention, examples of the azo group-containing dimethylpolysiloxane include VPS-500 and VPS-1000 (manufactured by Wako Pure Chemical Industries, Ltd.), which are polymerizable. Examples of unsaturated fatty acids include (meth) acrylic acid and itaconic acid, and examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. , Isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) Octyl acrylate,
Examples thereof include hydroxyethyl (meth) acrylate, methyl itaconate and ethyl itaconate. The shape of the alkyl group of the (meth) acrylic acid ester may be linear, branched or cyclic, and the carbon number thereof is in the range of 1 to 12. When the carbon number exceeds 12, the glass transition temperature becomes low and the film forming property and durability deteriorate. The polymerization ratio of each monomer of the polymer used in the present invention is as follows: azo group-containing dimethylpolysiloxane 10 to 70% by weight, polymerizable unsaturated carboxylic acid 1
5 to 70% by weight, (meth) acrylic acid ester 10 to 5
The range is 0% by weight. The preferred range is 20 to 50% by weight of azo group-containing dimethylpolysiloxane, 30 to 60% by weight of polymerizable unsaturated carboxylic acid, and 10 to 40% by weight of (meth) acrylic acid ester. Since the azo group-containing dimethylpolysiloxane also plays a role as a polymerization initiator, if the polymerization ratio is less than 10% by weight, the polymerization does not sufficiently occur, and if it exceeds 70% by weight, the film-forming property and the adhesion to the article to be coated are deteriorated. descend. This is because if the polymerization ratio of the polymerizable unsaturated carboxylic acid is less than 15% by weight, the solubility in the solvent used for synthesizing silica is deteriorated even if ammonia or a volatile amine is present. If the polymerization ratio of the (meth) acrylic acid ester is less than 10% by weight, the film-forming property and the adhesion to the object to be coated are deteriorated, and if it exceeds 50% by weight, the polymerizable unsaturated fatty acid and the azo group-containing dimethylpolysiloxane are contained. Less rate,
Solubility in reaction solvent is poor and water repellency is reduced. The acid value of the copolymer is preferably in the range of 50 to 500. When the acid value of the copolymer is less than 50, the solubility of the copolymer in the silica synthesis solvent becomes poor. If it exceeds 500, the water repellency becomes poor.

General formula (2) Si (OR^Four)_Four (In the formula, R^FourRepresents a straight chain alkyl group or a branched alkyl group
Forget ), An example of an alkoxysilane is
Tramethoxysilane, tetraethoxysilane, tetrap
Representative examples include ropoxysilane and tetrabutoxysilane.
Can be listed. General formula (3) R⁵ _nSi (OR⁶)_4-n (In the formula, R⁵Is an alkyl group, a fluoroalkyl group or a
Nyl group, R⁶Represents a straight chain alkyl group or a branched alkyl group
Here, n represents an integer of 1 to 3. ) Arco
Examples of xysilane include CH_Three(CH_Two)₅Si (OC
H_Three)_Three  , CH_Three(CH_Two)₉Si (OCH_Three)_Three, CH
_Three(CH_Two)₁₁Si (OCH_Three)_Three  , CH_Three(CH_Two)₇
Si (OCH_Three)_Three, CH_Three(CH_Two)₉Si (OC_TwoH
₅)_Three  , CH_Three(CH_Two)₁₁Si (OC_TwoH₅) _Three  , (C
H_Three)_TwoCHCH_TwoSi (OCH_Three)_Three  , CH_Three(C
H_Two)₉SiCl_Three, CF_ThreeCH_TwoCH_TwoSi (OC
H_Three)_Three, CF_Three(CF_Two)₇CH_TwoCH_TwoSi (OC
H_Three)_Three CH_Two= CHSi (OCH_Three)_Three  , CH_Two= C
HSi (OC_TwoH₅)_ThreeAnd so on. General formula (4) R⁷ _ThreeSiNHSiR⁷ _Three (In the formula, R⁷Is a linear alkyl group or a branched alkyl group
Represent. ) Alkyldisilazane
As an example of rukirjisilazane, (CH_Three)_ThreeSiNH
Si (CH_Three)_Three  , (C_TwoH₅)_ThreeSiNHSi (C_TwoH
₅)_ThreeAnd so on. Furthermore, in the present invention, the general formula
(2) Si (OR^Four)_Four(In the formula, R^FourIs a straight-chain alkyl group
Or represents a branched alkyl group. ) Alkoxy
Of silane, 5 to 80% by weight of the general formula (3) R⁵ _n
Si (OR⁶)_4-n(In the formula, R⁵Is an alkyl group,
Low alkyl group or vinyl group, R⁶Is a straight chain alkyl group
Represents a branched alkyl group, and n represents an integer of 1 to 3.
You ) Or an alkoxysilane represented by the general formula (4)
R⁷ _ThreeSiNHSiR⁷ _Three(In the formula, R⁷Is a straight-chain alk
Group or a branched alkyl group. ) Archi
Replacing with luzisilazane further improves water repellency.
If less than 5% by weight or more than 80% by weight, such effects
I could not confirm.

The solvent that can be used in the present invention may be any water-soluble solvent, examples of which include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, and water.
It is also possible to use two or more types in combination. The volatile alkaline substance that can be used in the present invention may be any volatile substance that exhibits alkalinity, and typical examples thereof include ammonia and volatile amines. Examples of volatile amines include diethylamine (DEA), triethylamine (TEA) and the like. Ammonia and volatile amines can be used alone or in combination of two or more.
Volatile alkaline substances are used as hydrolysis catalysts for alkoxysilanes. Ammonia and volatile amines are considered to exist as a salt of the polymer of the general formula (1) in the reaction system. After acting as a hydrolysis catalyst, ammonia and volatile amines are desorbed from the salt of the polymer of the general formula (1), so that the polymer exhibits water repellency. An example of this is shown in FIG. When a non-volatile amine is used, it can be hydrolyzed but it exists as a salt of the polymer of the general formula (1).
Does not show water repellency. The water-repellent silica fine particles of the present invention are usually composed of silica, a copolymer and a diluting solvent thereof, but if necessary, pigments, dyes, plasticizers, ultraviolet absorbers and the like within a range not impairing the object of the present invention. Various additives and other solvents can be added. The method of applying the water-repellent silica fine particles according to the present invention includes, for example, application with an applicator such as a sponge, brush or roller, dip coating with an object to be coated in the composition of the present invention, spray coating with an atomizer, or the composition of the present invention. For example, spray coating with an aerosol in which a container is enclosed with a propellant is used. Furthermore, the water-repellent silica fine particles according to the present invention can be used for protecting or coating the surface of a material such as metal, plastic, glass, ceramic, wood, or the coated surface thereof.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 Methacrylic acid (40% by weight), methacrylic acid ester (20% by weight), azo group-containing polydimethylsiloxane (40% by weight) (VPS-500: manufactured by Wako Pure Chemical Industries, Ltd.) was added to 2-propanol. The acrylic silicone resin (CTS-1) polymerized in was used. Acrylic silicone resin (CTS-1) (0.125 g) was dissolved in 50 ml of water: ethanol = 1: 1 (weight ratio). 28
% Of aqueous ammonia was added and dissolved in water-ethanol of acrylic silicone resin, and then tetraethoxysilane (TEOS) (4 g) was added dropwise. A silica dispersion colloid was obtained by stirring at room temperature for 2 hours. The obtained colloidal solution was applied on a glass substrate and dried.

[Examples 2 to 3] Solvent was water: ethanol =
A silica-dispersed colloid was obtained in the same manner as in Example 1 except that water (Example 2) or methanol (Example 3) was used instead of 1: 1 (weight ratio). The obtained colloidal solution was applied on a glass substrate and dried.

[Examples 4 to 9] Using the acrylic silicone resin (CTS-1) of Example 1, the concentration of the acrylic silicone resin (CTS-1) in the solvent was changed from 0.1% by weight to 5%.
The solvent was changed to about 0% by weight, and the solvent was water (Example 4), methanol (Example 5), ethanol: water = 3: 1 (weight ratio) (Example 6), water: ethanol = 1: 1 (weight). ratio)
(Example 7), isopropanol: water = 1: 1 (weight ratio) (Example 8), isopropanol 3: 1 (weight ratio)
Using (Example 9), 4 ml of 28% ammonia water was added to dissolve the acrylic silicone resin, and then 4 g (TEOS) of tetraethoxysilane was added dropwise. A silica dispersion colloid was obtained by stirring at room temperature for 2 hours. The obtained colloidal solution was applied on a glass substrate and dried. After aging the obtained dry film, the contact angle was measured. The result is shown in FIG. As is clear from this figure, good results were obtained when the concentration of the acrylic silicone resin (CTS-1) was 10% by weight or more.

[Example 10] Methacrylic acid (25% by weight), butyl methacrylate (25% by weight), azo group-containing polydimethylsiloxane (50% by weight) (VPS-50)
0: manufactured by Wako Pure Chemical Industries, Ltd.) was used as an acrylic silicone resin (CTS-2) polymerized in 2-propanol. Acrylic silicone resin (CTS-2) 0.1g
Was dissolved in 50 ml of water: ethanol = 3: 1 (weight ratio), and 4 g of 28% ammonia water. 4 g of tetraethoxysilane (TEOS) was added dropwise, and the mixture was stirred at room temperature for 2 hours to obtain a silica dispersed colloid. The obtained colloidal solution was applied on a glass substrate and dried. The contact angle with water was measured and found to be 108 degrees.

Example 11 0.1 g of the acrylic silicone resin (CTS-2) of Example 10 was mixed with 50 ml of water: ethanol = 3: 1 (weight ratio), and 4 g of 28% ammonia water.
Dissolved in. Tetraethoxysilane (TEOS) 4g
And decyltrimethoxysilane (DTMS: CH
_{3 (CH 2) 9 Si (} OCH 3) 3) was added dropwise and 1g, by stirring at room temperature for 2 hours to obtain a silica dispersion colloid. The obtained colloidal solution was applied on a glass substrate and dried. The contact angle with water was measured and found to be 141 degrees.

[Example 12] A silica dispersed colloid was obtained in the same manner as in Example 11 except that hexamethyldisilazane (HMDS) was used instead of decyltrimethoxysilane in Example 11. The obtained colloidal solution was applied on a glass substrate and dried. The contact angle with water was measured and found to be 112 degrees.

Comparative Example 1 50 ml of water: ethanol = 3:
4 g of tetraethoxysilane (TEOS) was added dropwise to a mixed solution of 1 (weight ratio) and 4 g of 28% ammonia water,
A silica dispersion colloid was obtained by stirring at room temperature for 2 hours. Apply the obtained colloidal solution to a glass substrate,
Dried. When the contact angle with water was measured, it was 20 degrees. [Comparative Example 2] 50 ml of water: ethanol = 3: 1 (weight ratio)
4 g of tetraethoxysilane (TEOS) and 1 g of decyltrimethoxysilane (DTMS) were added dropwise to a mixed solution of 4 g of 28% ammonia water and 28%, and the mixture was stirred at room temperature for 2 hours to obtain a silica dispersion colloid. The obtained colloidal solution was applied on a glass substrate and dried. The contact angle with water was measured and found to be 48 degrees.

[0016]

Since the water repellent of the present invention exhibits a large contact angle with water, it protects the article to be coated. It also has anti-icing and anti-frost effects.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of aging time and contact angle of acrylic silicone-triethylamine.

FIG. 2 is an explanatory diagram of CTS concentration and contact angle in Examples 4 to 9.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaki Kimoto             2-6-40 Aioi-dori, Abeno-ku, Osaka-shi, Osaka Prefecture             101 (72) Inventor Ayako Hioki             1-35-1 Higashi-Asakayama-cho, Sakai City, Osaka Prefecture (72) Inventor Masahiro Eikawa             129-113 Yasu, Noguchi, Noguchi-cho, Kakogawa-shi, Hyogo             Todoromi I 204 (72) Inventor Hideo Nishida             3-18, Kanoko Tainan-cho, Kita-ku, Kobe-shi, Hyogo Prefecture             17 (72) Inventor Hideki Waka             15-2 Meuntsuka Town, Takarazuka City, Hyogo Prefecture (72) Inventor Kunio Arimoto             2-10-23 Hasuike, Arai Town, Takasago City, Hyogo Prefecture (72) Inventor Noriyuki Ikeda             3-7-4 Incheon-cho, Nishinomiya-shi, Hyogo F-term (reference) 4G072 AA25 AA28 BB05 CC13 GG01                       GG03 HH28 HH29 HH30 MM01                       QQ07 RR05 RR12 UU30                 4H020 AA01 AA03 AB02 BA32 BA33                 4J037 AA18 CC28 DD25 EE02 EE28                       EE43

Claims (4)

[Claims] 1. The general formula (1) [Chemical 1] (In the formula, x is an integer of 5 to 300, R¹, R^TwoIs methyl
Group, hydrogen atom, acetic acid group, or acetic acid ester group, R^ThreeIs straight
Chain alkyl group, branched alkyl group or hydroxyalkyl
Represents a group, and l, m, and n each represent a molar ratio. )
The acrylic silicone resin solution shown in
Formula (2) with alkaline substance added Si (OR^Four)_Four (In the formula, R^FourRepresents a straight chain alkyl group or a branched alkyl group
Forget ) One or two kinds of alkoxysilanes represented by
By adding the above and hydrolyzing the alkoxysilane,
Water-repellent silica fine particles obtained. 2. A weight ratio of the acrylic silicone resin represented by the general formula (1) to one or more alkoxysilanes represented by the general formula (2) is 1: 9 to 9: 1. 2. The water-repellent silica fine particles according to claim 1. 3. An alkoxysila represented by the general formula (2)
5-80% by weight of General formula (3) R⁵ _nSi (OR⁶)_4-n (In the formula, R⁵Is an alkyl group, a fluoroalkyl group or a
Nyl group, R⁶Represents a straight chain alkyl group or a branched alkyl group
Here, n represents an integer of 1 to 3. ) Arco
Xysilane or General formula (4) R⁷ _ThreeSiNHSiR⁷ _Three (In the formula, R⁷Is a linear alkyl group or a branched alkyl group
Represent. ) 1 or 2 of alkyldisilazane
The method according to claim 1 or 2, characterized in that it is replaced with at least one species.
The water-repellent silica fine particles described. 4. [Chemical 2] (In the formula, x is an integer of 5 to 300, R¹, R^TwoIs methyl
Group, hydrogen atom, acetic acid group, or acetic acid ester group, R^ThreeIs straight
Chain alkyl group, branched alkyl group or hydroxyalkyl
Represents a group, and l, m, and n each represent a molar ratio. )
The acrylic silicone resin solution shown in
Formula (2) with alkaline substance added Si (OR^Four)_Four (In the formula, R^FourRepresents a straight chain alkyl group or a branched alkyl group
Forget ) One or two kinds of alkoxysilanes represented by
In addition to the above, or the alkoxy sila of the general formula (2)
5-80% by weight General formula (3) R⁵ _nSi (OR⁶)_4-n (In the formula, R⁵Is an alkyl group, a fluoroalkyl group or a
Nyl group, R⁶Represents a straight chain alkyl group or a branched alkyl group
Here, n represents an integer of 1 to 3. ) Arco
Xysilane or General formula (4) R⁷ _ThreeSiNHSiR⁷ _Three (In the formula, R⁷Is a linear alkyl group or a branched alkyl group
Represent. ) Was substituted with an alkyldisilazane
To add things to hydrolyze the alkoxysilane
Water-repellent silica for drying silica colloid obtained
Method for producing fine particles.