| 摘要 |
<p>Foamed thermoplastic polymer is prepd. from a) a core polymer based on: a1) 12-50 mol. % maleic acid and/or maleic anhydride: a2) a vinyl monomer; and a3) opt. a third monomer; where (a1) + (a2) + (a3) = 100 mol. % and the wt. average molecular wt. of the core polymer is 50,000-500,000; and (b) opt. a nucleating agent. The polymer is introduced into appts. suitable for foaming. (a) and (b) are brought to a temp. high enough to release CO2 from (a), so that the polymer melt is expanded to form a polymer foam. Also claimed are: 1) an intermediate for foaming an intrinsically expandable thermoplastic polymer, comprising (a), (b) and a basic catalyst; ii) a thermoplastic foam obtd. by the above process; and iii) a polymer foam comprising a polymer of a vinyl monomer, maleic acid anhydride monomer and at least 1 wt. % of spirodilacton. The core polymer is brought to a temp. of 230-300 (pref. 240-280, esp. 250-270) deg. C. (a) comprises 22-40 (25-38) mol. % maleic acid and/or maleic anhydride. The vinyl monomer is a vinyl aromatic monomer, pref. styrene. The foam has a density of 0.05-0.95 (0.08-0.85) g/cm2. The basic catalyst may be a sterically hindered sec. amine.</p> |
