Surface-treated inorganic powder, production method thereof, and resin composition and dispersion comprising said surface-treated inorganic powder

A method of producing a surface-treated inorganic powder, comprising:

• a raw-material-for-surface-treatment preparation step of mixing:
• 100 parts by mass of a silane coupling agent having a (meth)acryloyl group;
• 0.3 part by mass to 50 parts by mass of a polymerization inhibitor;
• and an inorganic powder, to thereby prepare a raw material for surface treatment;
• a surface treatment step of heating the raw material for surface treatment to 110° C. or more by a dry process, to thereby prepare a surface-treated raw material containing the inorganic powder surface-treated with the silane coupling agent;
• and
• a washing step of washing the surface-treated raw material.

A dispersion, comprising a surface-treated inorganic powder,

• wherein the surface-treated inorganic powder, which satisfies the following expression (1) and the following expression (2):
• 3.0≤D1≤50.0 Expression (1)
• 1.00≤D1/D2<1.10 Expression (2)
• in the expression (1) and the expression (2), D1 represents a presence amount (μmol/m2) of double bonds contained in the surface-treated inorganic powder, and D2 represents a presence amount (μmol/m2) of double bonds contained in a washed powder, wherein the washed powder is a powder obtained by sequentially subjecting the surface-treated inorganic powder to treatments shown in the following <1> to <3>:
• <1> 50 mL of methanol and 10 g of the surface-treated inorganic powder are mixed to provide a dispersion liquid;
• <2> the dispersion liquid is treated with an ultrasonic disperser at an output of 40 W for 20 minutes to provide a slurry;
• and
• <3> solid matter obtained by centrifuging the slurry and removing a supernatant is dried under reduced pressure at a pressure of 0.1 MPa and a temperature of 50° C. for a treatment time of 12 hours to provide the washed powder.

A resin composition, comprising a surface-treated inorganic powder of,

• wherein the surface-treated inorganic powder, which satisfies the following expression (1) and the following expression (2):
• 3.0≤D1≤50.0 Expression (1)
• 1.00≤D1/D2<1.10 Expression (2)
• in the expression (1) and the expression (2), D1 represents a presence amount (μmol/m2) of double bonds contained in the surface-treated inorganic powder, and D2 represents a presence amount (μmol/m2) of double bonds contained in a washed powder, wherein the washed powder is a powder obtained by sequentially subjecting the surface-treated inorganic powder to treatments shown in the following <1> to <3>:
• <1> 50 mL of methanol and 10 g of the surface-treated inorganic powder are mixed to provide a dispersion liquid;
• <2> the dispersion liquid is treated with an ultrasonic disperser at an output of 40 W for 20 minutes to provide a slurry;
• and
• <3> solid matter obtained by centrifuging the slurry and removing a supernatant is dried under reduced pressure at a pressure of 0.1 MPa and a temperature of 50° C. for a treatment time of 12 hours to provide the washed powder.