RADIATION CURABLE PRIMARY COATINGS D1363 BT ON OPTICAL FIBRE Russian patent published in 2011 - IPC C09D175/14 C09D175/16 C03C25/10 C03C25/26 

FIELD: chemistry.

SUBSTANCE: radiation curable primary coating composition contains at least one urethane-(meth)acrylate functional oligomer and a photoinitiator, wherein the urethane-(meth)acrylate functional oligomer is a product of reaction of hydroxyethyl acrylate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, isophorone diisocyanate and polyether polyol in the presence of a catalyst and an inhibitor, where the urethane-(meth)acrylate functional oligomer contains (meth)acrylate groups, at least one polyol backbone chain and urethane groups, where 15% or more of the urethane groups are derivatives of one of 2,4- and 2,6-toluene diisocyanate or both, where at least 15% of the urethane groups are derivatives of isophorone diisocyanate, and where said urethane-(meth)acrylate functional oligomer has number-average molecular weight from at least 4000 g/mol to at least 15000 g/mol; and where the cured film of the radiation curable primary coating composition has equilibrium modulus of elasticity, measured as indicated in the description, which is equal to at least 1.2 MPa. The invention also relates to a method of coating glass optical fibre, involving (a) using a glass drawing column to obtain glass optical fibre, preferably at linear velocity between 750 m/min and 2100 m/min; (b) applying the radiation curable primary coating composition onto the surface of the optical fibre; and (c) optional exposure to radiation to cure said radiation curable primary coating composition. The cured primary coating composition on the optical fibre and conductor has the following properties after initial curing and after one month at 85°C and 85% relative humidity:A) % RAU from 84% to 99%; B) in-situ modulus of elasticity between 0.15 MPa and 0.60 MPa; and C) Tc of the tube -25°C to - 55°C.

EFFECT: improved coating characteristics.

13 cl, 2 tbl