hylsilyl]propyl] vinyl carbamide, N-[3-[(trimethylsiloxy)dimethylsilyl]propyl] vinyl carbamide and compounds of formulas (19) to (21) indicated below: [0042] wherein, in formulas (19) to (21), R11 is H or a methyl group and s is an integer of 1 to 3. [0043] For the purpose of obtaining good mechanical properties and of obtaining good resistance to disinfecting solutions and washing solutions, in t