Polymer powder, curable resin composition and cured material thereof
View Patent ↗A polymer powder (P) selected from a group consisting of (i) a polymer powder (P1) and (ii) a polymer powder (P2) is provided. The (i) polymer powder (P1) includes a (meth)acrylate-based polymer (A1) having a glass transition temperature of 0° C. or less, and the polymer powder has an acetone-soluble component of 5 mass % or more. The acetone-soluble component has a mass average molecular weight of 100,000 or more. The (ii) polymer powder (P2) has an acetone-soluble component of 2 mass % to 35 mass %, the acetone-soluble component has a mass average molecular weight of 100,000 or more, and has a volume average primary particle size (Dv) of 200 nm or more.
1. A polymer powder (P2), having a volume average primary particle size (Dv) of 200 nm or more and comprising an acetone-soluble component of 2 mass % or more and less than 30 mass %, the acetone-soluble component having a mass average molecular weight of 100,000 or more.
2. The polymer powder (P2) according to claim 1 , wherein the polymer powder (P2) has a refractivity of 1.48 to 1.51 at 20° C.
3. The polymer powder (P2) according to claim 1 , wherein the polymer powder (P2) is a methyl methacrylate-based polymer powder obtained by polymerizing a monomer raw material (a2) comprising 70 mass % to 99 mass % of methyl methacrylate and 30 mass % to 1 mass % of a monomer raw material other than methyl methacrylate to provide a vinyl polymer which is subsequently powderized.
4. The polymer powder (P2) according to claim 1 in particle form with particle sizes of 10 μm or less comprising a proportion of less than 30 vol % and having the following disintegration properties:
(1) diluting the polymer powder (P2) with ion exchanged water;
(2) performing supersonic irradiation at a frequency of 42 kHz and a power of 40 W for 3 minutes;
(3) determining particle size distribution through particle size distribution measurement by laser diffractive/scattering; and
(4) the particles with the particle sizes of 10 μm or less take a proportion of 30 vol % or more.
5. A pre-gelling agent for a curable resin, comprising the polymer powder (P2) according to claim 1 .
6. The pre-gelling agent for a curable resin according to claim 5 , providing the curable resin with a gelling property such that a ratio (G′B/G′A) of storage elastic modulus G′A at a gelling temperature of −20° C. to storage elastic modulus G′B at a gelling temperature of +20° C. for the curable resin composition is 100 or more, wherein the curable resin composition is prepared by adding 20 parts by mass of the polymer powder (P2) relative to 100 parts by mass of the curable resin.
7. A curable resin composition, comprising the polymer powder (P2) according to claim 1 and a curable resin.
8. The curable resin composition according to claim 7 , wherein the curable resin is an epoxy resin.
9. The curable resin composition according to claim 8 , wherein the epoxy resin is an alicyclic epoxy resin.
10. The curable resin composition according to claim 7 , wherein a cured material with a thickness of 3 mm, obtained by curing the curable resin composition comprising the polymer powder (P2) and the curable resin, has a total light transmittance of 70% or more at 23° C.
11. A cured material, obtained by curing the curable resin composition according to claim 7 .
12. A sealing material for optical semiconductors, comprising the curable resin composition according to claim 7 .