Reversibly crosslinkable polymethacrylate moulding compsn. - comprising methyl-methacrylate, furfuryl (meth)acrylate, vinyl] monomer(s) and bis:maleimide cpd.

摘要

A polymer compsn. thermoplastically workable at above 200 deg.C comprises (A) a vinyl polymer of Mw less than 500,000 g/mol, comprising (1) 50-99.9 methyl methacrylate (MMA); (2) 0.1-15 wt.% furfuryl methacrylate (FMA) and/or furfuryl acrylate; (3) 0-49.9 wt.% other vinyl monomers; and (B) a bismaleimide cpd. of formula (I). R = aliphatic and/or aromatic gp. with 4-3C which can further include other heteroatoms or atom gps. The wt. ratio of (A):(B) is 99.8-90:0.2-10. The compsn. contains under 100 deg.C stable cross-linking bridges through the reaction of the furyl gp. and (I). Pref. (A) comprises 90-99 wt.% MMA, 0.1-5 wt.% FMA and 0.1-5 wt.% 1-5C alkyl acrylates. (A) has a Mw of 50,000-200,000. USE/ADVANTAGE - Provide compsns. which can be covalently crosslinked, giving improved properties and which, on heating, give the reversal of crosslinking resulting in newly thermoplastic compsns. The compsns. have relatively low mol. wt., are easily formable and can be used many times. They have higher temp. stability and good mechanical stability. They can be recycled. A mixt. of 97.5g MMA, 2.5g FMA and 300g methylene chloride was heated to 70 deg.C, mixed with AIBN, kept at 70 deg.C for 15 hrs., the polymer recovered and 88.7g polymer of Mw 68,600 was obtd. The polymer was dissolved in methylene chloride to give a 30-50% soln. to which was added 4,4-bis(maleimido) diphenylmethane. The soln. was applied to a glass plate, and crosslinked at 50 deg.C. . (