| CPC C08L 25/14 (2013.01) [B42D 15/02 (2013.01); C08F 220/1804 (2020.02); C08F 220/1808 (2020.02); C08K 3/22 (2013.01); C08K 3/36 (2013.01); C08L 33/10 (2013.01); C09J 125/14 (2013.01); C09J 133/10 (2013.01); G03G 9/0825 (2013.01); G03G 9/08711 (2013.01); G03G 9/08728 (2013.01); G03G 9/09371 (2013.01); G03G 9/09725 (2013.01); C08K 2003/2213 (2013.01); C08K 2003/2237 (2013.01); C08K 2201/003 (2013.01); C08L 2207/53 (2013.01)] | 20 Claims |
|
1. Pressure-responsive particles comprising:
pressure-responsive base particles; and
first inorganic oxide particles,
wherein the pressure-responsive base particles contain a styrene-based resin which contains styrene and other vinyl monomers as polymerization components and a (meth)acrylic acid ester-based resin which contains at least two kinds of (meth)acrylic acid alkyl esters as polymerization components and in which a mass ratio of the (meth)acrylic acid alkyl esters to all polymerization components is 90% by mass or higher,
wherein among the at least two kinds of (meth)acrylic acid alkyl esters contained in the (meth)acrylic acid ester-based resin as polymerization components, a mass ratio between the two kinds of (meth)acrylic acid alkyl esters having the highest mass proportion is 80:20 to 20:80, and the pressure-responsive base particles have a core portion that contains the styrene-based resin and the (meth)acrylic acid ester-based resin and a shell layer that contains the styrene-based resin coats the core portion, wherein a mass ratio of styrene to all polymerization components of the styrene-based resin is 60% by mass or higher and 95% by mass or lower,
the other vinyl monomers that the styrene-based resin contains as the polymerization components include n-butyl acrylate,
the at least two kinds of (meth)acrylic acid alkyl esters contained in the (meth)acrylic acid ester-based resin as the polymerization component includes 2-ethylhexyl acrylate and n-butyl acrylate,
the first inorganic oxide particles include at least strontium titanate particles,
Db/Da which is a ratio of a number average particle diameter Db of the first inorganic oxide particles to a number average particle diameter Da of the pressure-responsive base particles is 0.05 or higher and 0.25 or lower,
the pressure-responsive particles have at least two glass transition temperatures, and
a difference between a lowest glass transition temperature and a highest glass transition temperature is 30° C. or higher.
|