JP3385728B2 - Surface treatment agents and binders - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treating agent and a binder for inorganic materials, which comprises a disilane-containing organopolysiloxane as a main component.

[0002]

2. Description of the Related Art Conventionally, silane coupling agents, organopolysiloxanes, silicates and the like have been mainly used as surface treatment agents and binders for inorganic materials. Since these substances have a curable functional group, it is possible to form a film by condensation curing at a low temperature, but it is difficult to avoid cracking due to volume shrinkage at high temperature, and heat resistance is poor.

Japanese Patent Laid-Open No. 5-295563 discloses an example of using polysilane which is less likely to cause cracks, but it is difficult to form a film at a low temperature equivalent to that of a silicone resin. Even at a high temperature of 400 ° C. according to the method described in the above publication, there are some which cannot form a film like dimethylpolysilane. Even the only methylphenylpolysilane that can be formed into a film is inferior in adhesiveness and chemical resistance, and a satisfactory product has not been obtained. Therefore, a surface treating agent and a binder which do not have the above-mentioned drawbacks have been desired.

[0004]

Means and Actions for Solving the Problems As a result of intensive investigations in order to meet the above-mentioned demands, the present inventor has found that a hydrolyzable group-containing disilane represented by the following general formula (2) or a partially hydrolyzed condensate thereof. Or by hydrolyzing the silane or its partial hydrolysis-condensation product and the hydrolyzable group-containing silane represented by the following general formula (3) or its partial hydrolysis-condensation product, the following average It was found that the disilane-containing organopolysiloxane represented by the composition formula (1) can be obtained.

R ¹ _c Si ₂ X _6-c (2) R ¹ _a SiX _4-a (3) [R ¹ _a Si (OR ² ) _b O _{(4-ab) / 2} ] _m [R ¹ _c Si ₂ (OR ² ) _d O _{(6-cd) / 2} ] _n (1) (wherein R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R ² is a hydrogen atom) And an alkyl group having 1 to 4 carbon atoms, wherein a, b, c and d are 0 ≦.
a ≦ 2, 0 ≦ b ≦ 3, 0 ≦ c ≦ 3, 0 <d <6, and 0 ≦
It is an integer that satisfies a + b <4 and 0 <c + d <6, m is 0 ≦ m ≦ 0.9, n is 0.1 ≦ n ≦ 1, and a positive number that satisfies m + n = 1. Further, X is an alkoxy group having 1 to 4 carbon atoms. )

When this disilane-containing organopolysiloxane is used as the main component of the surface treating agent for inorganic materials and the binder, it has a curable functional group as in the conventional silicone resin system, so that it can be used at low temperatures. It has been found that it is possible to form a film, and therefore productivity is improved, and further adhesion, chemical resistance and the like are also good.

Moreover, since it has a disilane skeleton in the molecule, at high temperature, an oxidation reaction of the Si-Si bond to the Si-O-Si bond occurs before or at the same time as the organic group is thermally decomposed, and the weight due to this oxidation reaction. Due to the increase, the volume shrinkage due to the thermal decomposition of the organic group is suppressed, so that the occurrence of cracks can be avoided and the heat resistance becomes good.

The disilane used as a raw material may be a chloro-containing disilane as a distillation residue produced as a by-product during silane synthesis. Since this disilane has been generally regarded as unsuitable as a raw material for synthesizing polysiloxane, it was often disposed of. However, according to the method of the present invention, industrial waste can be effectively used and it is possible to protect the global environment. preferable.

Therefore, the disilane-containing organopolysiloxane according to the present invention not only exerts performance effects such as heat resistance, adhesion, and chemical resistance, but also can utilize industrial waste as a raw material for its production. Further, they have found that the present invention is excellent in terms of protection of the global environment, and have completed the present invention.

Conventionally, as the organopolysiloxane containing a polysilane structure, those disclosed in JP-A-2-204410 and JP-A-2-202953 are known, and the polysilane-containing organopolysiloxanes of these publications are known. The polysilane structure is linear and has no curable functional group attached to the silicon atom of disilane. On the other hand, the disilane structure of the disilane-containing organopolysiloxane according to the present invention has a curable functional group bonded to the silicon atom of disilane, and has a crosslinked structure with polysiloxane.
It is structurally different and has excellent curing characteristics and adhesion. Further, the organopolysiloxane of the above publication is also an ultraviolet absorber or a hard coat film for use, but in consideration of the structures of both polysilane-containing organopolysiloxanes as described above, the organopolysiloxane of the present invention having a high crosslinking density is used. Polysiloxane is superior in film strength. Furthermore, the binding strength of the surface treatment of the inorganic material is also superior in the present invention in which the amount of curable functional groups in the molecule is large.

Therefore, the present invention has the following general formula (2) R ¹ _c Si ₂ X _6-c (2) (wherein R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. Is an alkoxy group having 1 to 4 carbon atoms, and c is an integer satisfying 0 ≦ c ≦ 3, and at least one of the hydrolyzable group-containing disilane and the partial hydrolyzed condensate thereof is hydrolyzed and condensed. Or at least one hydrolyzable group-containing disilane of the above formula (2) or a partial hydrolyzed condensate thereof and the following general formula (3) R ¹ _a SiX _4-a (3) (where R is ¹ and X have the same meanings as described above, and a is 0.
It is an integer that satisfies ≦ a ≦ 2. The following average compositional formula (1) [R ¹ _a Si (OR ² ) _b O obtained by cohydrolyzing and condensing with a hydrolyzable group-containing silane represented by _{(4-ab) / 2} ] _m [R ¹ _c Si ₂ (OR ² ) _d O _{(6-cd) / 2} ] _n (1) (wherein R ¹ has the same meaning as described above. R ² Is a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, a, b, c and d are 0 ≦ a ≦ 2, 0 ≦ b ≦ 3, 0 ≦ c ≦ 3, 0 <d <
6 is an integer satisfying 0 ≦ a + b <4 and 0 <c + d <6, m is 0 ≦ m ≦ 0.9, n is 0.1 ≦ n ≦ 1, and m is
It is a positive number that satisfies + n = 1. And a disilane-containing organopolysiloxane having a silicon atom-bonded hydroxyl group and an alkoxy group, which is represented by the formula (1), as a main component, and a surface treatment agent for an inorganic material and a binder.

The present invention will be described in more detail below.
The disilane-containing organopolysiloxane of the present invention is represented by the following average composition formula (1). _{^{[R 1 a Si (OR 2)}} b O (4-ab) / 2 ] _{m ^{[R 1 c Si 2 (OR 2}} ) d O (6-cd) / 2 ] _n ... (1)

In the above formula, R ¹ _a Si (OR ² ) _b O
_{At least one of (4-ab) / 2} and R ¹ _c Si ₂ (OR ² ) _d O _{(6-cd) / 2} preferably has a branched structure. a is 0 ≦
a ≦ 2, more preferably 0.5 ≦ a ≦ 1.5, b is 0 ≦
b ≦ 3, more preferably 0.1 ≦ b ≦ 1, and 0 ≦ a + b
It is an integer that satisfies <4. When a> 2, the molecular weight is lowered, so that the volatile component increases and the processing efficiency decreases, which is not preferable. c is 0 ≦ c ≦ 3, d is 0 <d <6
Is an integer satisfying 0 <c + d <6, and more preferably 0 <c + d <4. In particular, when 0 <c + d <4, the disilane structure has a branched structure, and the adhesiveness and heat resistance are more excellent.

Further, m is 0 ≦ m ≦ 0.9 and n is 0.1 ≦
It is a positive number satisfying m + n = 1 when n ≦ 1. m> 0.9
Further, if n <0.1, the effect of containing disilane in heat resistance cannot be obtained, which is not preferable.

R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1
The thing of -6 is preferable. Specifically, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group,
Examples thereof include alkyl groups such as heptyl group and octyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group, aryl groups such as phenyl group, aralkyl groups such as benzyl group and phenylethyl group. Some or all of the hydrogen atoms may be replaced with halogen atoms. Further, examples of the reactive group include an alkenyl group such as a vinyl group and an allyl group, an aliphatic unsaturated group-containing organic group-substituted alkyl group such as an allyloxypropyl group and a methacryloxypropyl group. Of these, a particularly preferred one is a methyl group.

R ² is a hydrogen atom or an alkyl group, and the alkyl group has 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group and butyl group.

The disilane-containing organopoly of the above formula (1)
Siloxane is represented by the following general formula (2)       R¹ _cSi₂X_6-c                                     … (2) (However, R¹And c have the same meanings as above, and X is
It is a water-degradable group. ) Hydrolyzable group-containing disi
At least one orchid or its partial hydrolysis-condensation product is added.
Water decomposition condensation (when m = 0 in formula (1)),
Alternatively, the hydrolyzable group-containing disilane of the above formula (2) or its
At least one of the partial hydrolysis-condensation products of
(3)       R¹ _aSi X_4-a                                      … (3) (However, R¹, A and X have the same meanings as above. )
Hydrolyzable group-containing silane represented by or its partial hydrolysis
Co-hydrolytically condensing with at least one decondensate
(When m> 0 in formula (1))
You can

Here, in the disilane of the formula (2), c
Is an integer of 0 ≦ c ≦ 3 as described above, and c is c> 3.
If so, the cross-linking rate is lowered, so that the heat resistance is inferior and the adhesiveness is lowered, which is not preferable.

The hydrolyzable group X is an alkoxy group having 1 to 4 carbon atoms.

Further, this disilane can be obtained as a high boiling point distillate produced as a by-product during the silane synthesis which is usually carried out by the reaction between metal silicon and an alkyl halide, and the high boiling point is taken into consideration in view of the production cost and the global environment. Preference is given to using fractions.

Therefore, a suitable hydrolyzable group X is a chlorine atom obtained as a high boiling fraction or an alkoxy group which can be derived at a low cost by reaction with a chlorine atom or the like.

Specific examples of the hydrolyzable group-containing disilane used in the present invention are as follows. _{(CH 3 O) 3 SiSi (} OCH 3) 3, (CH 3 O) 2 CH
_{3 SiSi (OCH 3) 3,} (CH 3 O) 2 CH 3 SiSiC
H ₃ (OCH ₃ ) ₂ , (CH ₃ O) ₃ SiSi (CH ₃ ) ₂ O
CH ₃ , (CH ₃ O) ₂ CH ₃ SiSi (CH ₃ ) ₂ OC
H ₃ , (CH ₃ O) ₃ SiSi (CH ₃ ) ₃ , Cl ₃ SiSi
Cl ₃ , Cl ₂ CH ₃ SiSiCl ₃ , Cl ₂ CH ₃ SiSi
CH ₃ Cl ₂ , Cl ₃ SiSiCH ₃ , Cl ₂ CH ₃ SiSi
CH ₃ Cl

The disilane-containing organopolysiloxane of the formula (1) in which m = 0 is used as a raw material of the hydrolyzable group-containing disilane satisfying the above conditions and / or its partial hydrolyzed condensate, either alone or in combination of two or more. It can be obtained by hydrolytic condensation under acidic or basic conditions according to a known method.

In the formula (1), the disilane-containing organopolysiloxane having m> 0 is obtained by converting the hydrolyzable group-containing silane represented by the formula (3) and / or its partial hydrolysis-condensation product into the hydrolyzable group. It is obtained by mixing with the contained disilane and / or its partial hydrolyzed condensate and co-hydrolyzed and condensed.

Specific examples of the hydrolyzable group-containing silane and its partially hydrolyzed condensate used in the present invention are as follows.

[0026]

[Chemical 1]

In addition to the methoxy group-containing silane and oligomer, various alkoxy groups and other hydrolyzable groups are included, and the examples are not limited to the above.

The above-mentioned hydrolytic condensation and co-hydrolytic condensation can be carried out by a known method as described above, but hydrochloric acid, sulfuric acid, methanesulfonic acid or the like is used as a catalyst especially when carried out under acidic conditions. And 0.5 at 0-200 ° C
The reaction is preferably carried out for -24 hours, and when carried out under basic conditions, it is preferable to carry out the reaction at 0-200 ° C for 1-48 hours using ammonia, sodium carbonate or the like as a catalyst.

The disilane-containing organopolysiloxane of the present invention is used as a main component of a surface treating agent for inorganic materials or a binder. When used for such an application, the disilane-containing organopolysiloxane is sufficiently mixed with an organic solvent such as toluene to form a uniform solution state, which is then uniformly coated on the surface of the inorganic material and sufficiently dried to be deposited. This time,
Similar to known silicone resin surface treatments or binders,
Known curing catalysts such as acidic, basic and metal compounds may be added. Further, it may be used in combination with an inorganic substance reinforcing material such as mica, silica, titanium oxide, and aluminum oxide.

Thereafter, a heat treatment is performed in the air or in an oxygen atmosphere, and an oxidation reaction is caused if necessary to obtain an inorganic material surface-modified with the disilane-containing organopolysiloxane. In this case, the heat treatment can be performed at 20 to 250 ° C. for 10 minutes to 10 hours.

As specific examples of the inorganic material, iron,
Copper, nickel, aluminum, silicon, stainless steel, brass, glass cloth, brick, etc. are not particularly limited. The shape is not particularly limited, and may be rod-shaped, tubular, bulk-shaped, fiber-shaped, film-shaped, or powder-shaped.

[0032]

Since the disilane-containing organopolysiloxane of the present invention has a curable functional group, it can be formed into a film at a low temperature, has a high hardness, and cracks due to volume contraction at a high temperature occur. No, the heat resistance is good. Therefore, it can be effectively used as a surface treatment agent or a binder for inorganic materials.

Further, according to the production method of the present invention, such a disilane-containing organopolysiloxane can be produced easily and reliably.

[0034]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1 A 0.3-liter separable flask equipped with a cooling tube, a thermometer, and a dropping funnel was placed in a 1,2-
20 g (96 mmol) of dimethyl-1,1,2,2-tetramethoxydisilane, 100 g (735 mmol) of methyltrimethoxysilane, 91.6 g of toluene,
Further, 9.2 g of isopropyl alcohol was charged and the mixture was stirred at room temperature. After adding 1.9 g of methanesulfonic acid with stirring, 23.7 g of water was added dropwise over 20 minutes, and the temperature inside the flask was raised to 45 ° C.

Further, after stirring at room temperature for 1 hour, the reaction solution was dissolved.
Liquid is 20% Na ₂SO_FourWashed with aqueous solution, Na₂SO_FourDry
did.²⁹Di-Si obtained from Si-NMR and functional group measurement
The average composition formula of the orchid-containing organopolysiloxane is [C
H₃Si (OR )_0.24O_1.38]_0.88[(CH₃)₂Si
₂(OR )_0.25O_1.88]_0.12(OR has an OH group of 50mo
1%, OCH₃Was 50 mol%). After filtration,
A toluene solution having a volatile content of 50% was prepared.

[Examples 2 to 4] In Example 1, Table 1
1,2-dimethyl-1,1,2,2-tetramethoxydisilane was added in increments of 10 g, and a toluene solution having a nonvolatile content of 50% was obtained by the same procedure.

[Embodiment 5] 1,2-Dimethyl-1,1,2,2-tetramethoxydisilane was added to a 200 ml separable flask equipped with a cooling tube, a thermometer and a dropping funnel.
0.0g (238 mmol) and 50.0 g of methanol
Charge and stir at room temperature. Under stirring, 9.4 g of 0.01 N hydrochloric acid solution was added dropwise over 10 minutes, and the temperature inside the flask was raised to 38 ° C.

Further, the mixture was stirred at room temperature for 3 hours to obtain toluene.
The solvent was replaced with, and a toluene solution with a nonvolatile content of 50% was prepared.
It was²⁹Disila obtained from Si-NMR and functional group measurement
The average composition formula of the silane-containing organopolysiloxane is [(C
H₃)₂Si Si (OR )_0.21O_1.90] (OR has an OH group
40 mol% and OMe group was 60 mol%).

[Embodiment 6] A cooling tube, a thermometer, and a dropping funnel are installed.
Add a 1,2-dimension to a 300 ml separable flask attached.
Chill-1,1,2,2-tetramethoxydisilane and 1,
1,2-trimethyl-1,2,2-trimethoxydisila
100 g of a mixture with toluene (mixing molar ratio 2: 1) and toluene
Charge 104.2g, 8.9g isopropyl alcohol
And stirred at room temperature.²⁹Si-NMR and functional group measurement
Average of disilane-containing organopolysiloxanes obtained from
The composition formula is [(CH₃)_2.5Si Si (OR )
_0.19O_1.91] (OR is 40 mol% OH group, OMe group
Was 60 mol%). Hereinafter, the same procedure as in Example 1
In order, a toluene solution having a nonvolatile content of 50% was obtained.

[Comparative Example 1] A cooling tube, a thermometer, and a dropping funnel were installed.
Add a methyl trimmer to a 300 ml separable flask attached.
Toxylsilane 100 g (735 mmol) and toluene 7
Charge 3 g and 7.6 g of isopropyl alcohol at room temperature
It was stirred at.²⁹Obtained from Si-NMR and functional group measurements
Average compositional formula of disilane-containing organopolysiloxane
Is [CH₃SiO_3/2] Met. Hereinafter, the same as in Example 1.
By the same procedure, a toluene solution having a nonvolatile content of 50% was obtained.

Comparative Example 2 300 ml of dehydrated THF and 7 g of metal lithium (1.0 m) in a 500 ml three-necked flask equipped with a gas introduction tube, a cooling tube, a thermometer and a dropping funnel.
ol) and 1.3 g of crown ether were charged, and the mixture was cooled to 0 ° C. under a nitrogen atmosphere. After cooling, 65 g (0.5 mol) of dichlorodimethylsilane was added dropwise over 40 minutes, and after the addition, the mixture was stirred at room temperature for 18 hours. The reaction mixture was extracted with hot toluene, the extraction solution was concentrated, and dimethylpolysilane was added to
1.5 g was obtained. As a result of measuring the molecular weight by GPC, the average molecular weight was about 1900 (in terms of polystyrene). The average composition formula is shown below.

[0043]

[Chemical 2]

[Comparative Example 3] Methylphenylpolysilane was synthesized in the same manner as in Comparative Example 2 using methylphenyldichlorosilane instead of dichlorodimethylsilane in the above reaction. As a result of measuring the molecular weight by GPC, the average molecular weight was about 1600 (in terms of polystyrene). The average composition formula is shown below.

[0045]

[Chemical 3]

The physical properties of the silicone varnishes obtained in Examples 1 to 6 and Comparative Example 1 are shown in Table 1.

[0047]

[Table 1]

The disilane-containing organopolysiloxanes of Examples 1 to 5 and the organopolysiloxane of Comparative Example 1 were subjected to thermogravimetric measurement (TG). Co., Ltd. for measurement
Rigaku Thermoflex TG8110 was used. In addition, as a sample, 2 g of a toluene solution having a nonvolatile content of 50% was taken in an aluminum petri dish and placed in an oven at 150 ° C. for heat condensation for 1 hour. Further, a powdered product in a mortar was used. The thermogravimetric results are shown in FIG.

As is clear from the results shown in FIG. 1, it is recognized that the disilane-containing organopolysiloxane is superior in heat resistance to the organopolysiloxane.

Example 7 A 50% toluene solution of the disilane-containing organopolysiloxane obtained from Examples 1 to 6 and 5% of the organopolysiloxane obtained from Comparative Example 1
10 g of each 0% toluene solution was taken, and phosphoric acid was added to 0.
After adding 06 g and stirring sufficiently to form a uniform solution state,
It was applied to the surface of an iron plate having a size of 150 mm × 50 mm. After application, the solvent was evaporated and dried, and heat treatment was performed in air at a temperature of 150 ° C. for 1 hour. As a result, an iron plate whose surface was coated with a silicone resin was obtained.

The polysilanes obtained in Comparative Examples 2 and 3 were dissolved in toluene to prepare 5% solutions. This solution was applied on the surface of an iron plate having a size of 150 mm × 50 mm, and then the solvent was vaporized and dried. After drying and treatment in air at a temperature of 400 ° C. for 3 hours, an iron plate coated with methylphenylpolysilane was obtained, but not with dimethylpolysilane.

With respect to the iron plate obtained by the above method, the performance of the coating film was measured in the following manner. The results are shown in Table 2. The appearance was visually observed. Film Thickness Gauge (Sankou Denshi Laboratory Inc. Electromagnetic Thickness Gauge SL)
-110) was used to measure the thickness of the coating. Hardness A pencil scratching test was performed according to JIS-K5401. Adhesion According to JIS-K5401, a 100-mm square cross-cut test was performed, and a cellophane tape peeling test was performed. Chemical resistance After immersing in a refluxed toluene solution for 24 hours, the film was observed. The presence or absence of the polymer compound was confirmed by GPC analysis of the toluene solution. Heat resistance The film obtained by curing at 150 ℃ for 1 hour is further heated at 350 ℃.
After being cured for 3 hours, the state of the coating film was visually observed.

[0053]

[Table 2]

[Example 8] 50% toluene solution 1 of disilane-containing organopolysiloxane obtained in Example 3
1 g of triethanolamine was added to 000 g, and this liquid was impregnated with glass cloth. Then, it was air-dried for 30 minutes and further pre-dried at 110 ° C. for 10 minutes. The pickup at this time was between 35 and 40% by weight. Cut this piece into 31 cm x 31 cm and stack 15 sheets to make 1
From a molding pressure of 0 kg / cm ^2, the laminate was manufactured by heating to 180 ° C. and holding at this temperature for 1 hour.

Table 3 shows the characteristics of the laminate obtained by the above method.

[0056]

[Table 3]

From the results shown in Tables 2 and 3, it was confirmed that the disilane-containing organopolysiloxane of the present invention had excellent performance as a surface treatment agent and a binder.

[Brief description of drawings]

FIG. 1 is a graph showing thermogravimetric measurement results of disilane-containing organopolysiloxanes of Examples 1 to 5 and silane hydrolyzates of Comparative Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Isobe 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) Reference JP-A-6-16815 ( JP, A) JP 3-24131 (JP, A) JP 63-260925 (JP, A) JP 30-1247 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 77/48 C03C 25/10 C04B 41/84 C09D 183/14

Claims (2)

(57) [Claims] 1. The following general formula (2) R ¹ _c Si ₂ X _6-c (2) (wherein R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. X is the number of carbon atoms. 1 to 4 alkoxy groups, c is an integer satisfying 0 ≦ c ≦ 3, or at least one of the hydrolyzable group-containing disilane represented by the formula or a partial hydrolysis-condensation product thereof is hydrolyzed and condensed, or Alternatively, at least one hydrolyzable group-containing disilane represented by the above formula (2) or a partial hydrolyzed condensate thereof and the following general formula (3) R ¹ _a SiX _4-a (3) (where R ¹ and X are Has the same meaning as above, and a is 0.
It is an integer that satisfies ≦ a ≦ 2. The following average compositional formula (1) [R ¹ _a Si (OR ² ) _b O obtained by cohydrolyzing and condensing with a hydrolyzable group-containing silane represented by _{(4-ab) / 2} ] _m [R ¹ _c Si ₂ (OR ² ) _d O _{(6-cd) / 2} ] _n (1) (wherein R ¹ has the same meaning as described above. R ² Is a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, a, b, c and d are 0 ≦ a ≦ 2, 0 ≦ b ≦ 3, 0 ≦ c ≦ 3, 0 <d <
6 is an integer satisfying 0 ≦ a + b <4 and 0 <c + d <6, m is 0 ≦ m ≦ 0.9, n is 0.1 ≦ n ≦ 1, and m is
It is a positive number that satisfies + n = 1. ) A surface treatment agent for an inorganic material, the main component of which is a disilane-containing organopolysiloxane having a silicon atom-bonded hydroxyl group and an alkoxy group represented by the formula (1). 2. The following general formula (2) R ¹ _c Si ₂ X _6-c (2) (wherein R ¹ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. X is a carbon number. 1 to 4 alkoxy groups, c is an integer satisfying 0 ≦ c ≦ 3, or at least one of the hydrolyzable group-containing disilane represented by the formula or a partial hydrolysis-condensation product thereof is hydrolyzed and condensed, or Alternatively, at least one hydrolyzable group-containing disilane represented by the above formula (2) or a partial hydrolyzed condensate thereof and the following general formula (3) R ¹ _a SiX _4-a (3) (where R ¹ and X are Has the same meaning as above, and a is 0.
It is an integer that satisfies ≦ a ≦ 2. The following average compositional formula (1) [R ¹ _a Si (OR ² ) _b O obtained by cohydrolyzing and condensing with a hydrolyzable group-containing silane represented by _{(4-ab) / 2} ] _m [R ¹ _c Si ₂ (OR ² ) _d O _{(6-cd) / 2} ] _n (1) (wherein R ¹ has the same meaning as described above. R ² Is a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, a, b, c and d are 0 ≦ a ≦ 2, 0 ≦ b ≦ 3, 0 ≦ c ≦ 3, 0 <d <
6 is an integer satisfying 0 ≦ a + b <4 and 0 <c + d <6, m is 0 ≦ m ≦ 0.9, n is 0.1 ≦ n ≦ 1, and m is
It is a positive number that satisfies + n = 1. ) A binder for inorganic materials, which comprises, as a main component, a disilane-containing organopolysiloxane having a silicon atom-bonded hydroxyl group and an alkoxy group represented by the formula (1).