Surface-treated silica powder

Abstract

A surface-treated silica powder according to the present invention contains silica particles surface-treated with a silane coupling agent and has a configuration such that the hydrophobization level of the surface-treated silica powder is at least 20%; and where C (mass%) is the carbon content of the surface-treated silica powder, and S (m2 / g) is the specific surface area of the surface-treated silica powder that is measured using a BET one-point method due to nitrogen gas absorption, C and S satisfy 0.025≤C / S≤0.070.

Claims

1. A surface-treated silica powder comprising silica particles surface-treated with a silane coupling agent, The degree of hydrophobicity of the surface-treated silica powder, as determined according to procedure A below, is 20% or more, and Let C (mass%) be the carbon content of the surface-treated silica powder determined according to procedure B below, and let S (m²) be the specific surface area of ​​the surface-treated silica powder measured by the BET 1-point method using nitrogen gas adsorption. ２ A surface-treated silica powder in which, when expressed as (per g), C and S satisfy 0.025 ≤ C / S ≤ 0.

070. (Procedure A) The surface-treated silica powder is stored in an air environment at 20°C and 23% RH for 7 days to prepare the sample. Place a stirring bar in a flask, measure out 50 ml of deionized water at a liquid temperature of 25°C, and gently float 0.2 g of the sample on the surface of the water. Rotate the stirring bar and gently add methanol dropwise, ensuring it does not come into direct contact with the sample. The amount of methanol in each sample after it has settled from the water surface is measured, and the degree of hydrophobicity (%) is calculated based on the following formula. Degree of hydrophobicity (%) = [[Amount of methanol added (mL)] / [Amount of deionized water 50 mL + Amount of methanol added (mL)]] × 100 (Procedure B) Add 3 g of the surface-treated silica powder to 37 g of acetone and stir for 30 minutes. Then, run the slurry in a centrifuge at 3500 rpm for 10 minutes to separate the surface-treated silica powder from the acetone, and discard the supernatant solution of acetone. Repeat this acetone washing operation twice and dry at 120°C for 2 hours. The carbon content (mass%) in 0.3 g of washed surface-treated silica powder is measured using a carbon / sulfur simultaneous analyzer and quantified using the calibration curve method.

2. The surface-treated silica powder according to claim 1, A surface-treated silica powder in which, in the volume frequency particle size distribution of the surface-treated silica powder measured by laser diffraction scattering, D50 is defined as the particle size at which the cumulative value from the small particle size side accounts for 50%, and D50 is between 1 μm and 30 μm.

3. A surface-treated silica powder according to claim 1 or 2, A surface-treated silica powder in which, in the volume frequency particle size distribution of the surface-treated silica powder measured by laser diffraction scattering, the particle sizes at which the cumulative values ​​from the smallest particle size side reach 10%, 50%, and 90% are defined as D10, D50, and D90, respectively, and (D90 - D10) / D50 is between 0.3 and 7.

5.

4. A surface-treated silica powder according to claim 1 or 2, The specific surface area of ​​the surface-treated silica powder, as measured by the BET 1-point method using nitrogen gas adsorption, is 1.0 m². ２ / g or more 12.0m ２ Surface-treated silica powder with a weight of less than / g.

5. A surface-treated silica powder according to claim 1 or 2, Surface-treated silica powder with an average sphericity of 0.80 or higher.

6. A surface-treated silica powder according to claim 1 or 2, Surface-treated silica powder comprising a silane compound having one or more functional groups selected from the group consisting of epoxy groups, methacrylic groups, acrylic groups, amino groups, vinyl groups, alkyl groups, and phenyl groups, as the silane coupling agent.

7. A surface-treated silica powder according to claim 1 or 2, A surface-treated silica powder configured such that the thixotropy of the evaluation sample, as measured under the following conditions, is 0.021 or higher. (conditions) An evaluation sample is obtained by mixing 50% by volume of the surface-treated silica powder with 50% by volume of liquid silicone resin (DOWSIL SE1885A). The viscosity of the obtained evaluation sample was measured using a rheometer equipped with a conical cone (3 degrees) at 30°C and a shear rate of 1 [1 / s], and the viscosity was expressed as η. １ The viscosity measured at a shear rate of 100 [1 / s] is given by η １００ In this case, the above thixotropic ratio is η １００ / η １ It is calculated from this.

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