Cosmetic oil thickener and oil-soluble copolymer

A cosmetic containing an oil thickener, and at least one oil which is selected from the group consisting of a hydrocarbon oil, an ester oil, and a higher alcohol, wherein

• the oil thickener is an oil-soluble copolymer having a monomer unit composed of a hydrophilic monomer, a monomer unit composed of an easily-crystallizing hydrophobic monomer, and a monomer unit composed of a poorly-crystallizing hydrophobic monomer,
• the oil-soluble copolymer contains the monomer unit of the hydrophilic monomer in a range of 30 to 50 mol %, contains the monomer unit of the easily-crystallizing hydrophobic monomer in a range of 40 to 65 mol % and contains the monomer unit of the poorly-crystallizing hydrophobic monomer in a range of 5 to 15 mol %,
• the hydrophilic monomer is at least one selected from among 2-hydroxyethyl (meth)acrylate, glyceryl (meth)acrylate, PPG-6 (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, (meth)acrylic acid, N-(2-hydroxyethyl) (meth)acrylamide, N-isopropyl(meth)acrylamide, and 2-(meth)acrylamide-2-methylpropanesulfonic acid,
• the easily-crystallizing hydrophobic monomer is at least one selected from among cetyl (meth)acrylate, stearyl (meth)acrylate and behenyl (meth)acrylate,
• the poorly-crystallizing hydrophobic monomer is at least one selected from among hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate and isostearyl (meth)acrylate,
• the molar ratio of the monomer unit of the easily-crystallizing hydrophobic monomer and the monomer unit of the poorly-crystallizing hydrophobic monomer in the oil-soluble copolymer is 5.5:1 to 8:1,
• the amount of the oil thickener is 3 mass % or greater, in 100 mass % of a mixture of the oil thickener and the at least one oil,
• the cosmetic exhibits a static viscosity of between 100 Pa-s and 20,000 Pa-s under conditions of a shear rate of 0.0001 s−1 and 25° C. atmosphere and
• wherein the copolymer thickens the at least one oil without gelation.