Injection-moulding binders for metal or ceramic powder - contain dimer acid-based polyamide, polyfunctional epoxide and mould lubricant, esp. wax or long-chain fatty acid, alcohol or ester

摘要

Injection moulding binders for metal and/or ceramic powder are claimed (I). (I) contain (a) polyamides, polyesters, poly(meth)acrylates or polyurethanes with at least 2 COOH gps. on average, (b) polyfunctional epoxides and (c) waxes, esters of 6-32C mono- and/or di-carboxylic acids and 4-36C alcohols with 1-6 OH gps., 6-32C fatty acids or 6-32C fatty alcohols as mould lubricants. (a) Are polymers with m.w. 5000-30,000, pref. 10,000-20,000, esp. polyamides, pref. polyamides based on dimer fatty acids deriv. from oleic acid. (b) contains 2-6, pref. 3-5, epoxide gps. (average) per mol., and have softening pt. 70-250 (pref. 90-180) deg.C.. Pref. (b) has formula (IIA) or (IIB) (with x = 1-5. (c) have softening pt. below 100 (pref. below 70) deg.C. (ASTM E 28), and consist of waxes, esters of 12-36C mono-acids and 12-32C alkanols or 4-10C polyols with 3-6 OH gps., and/or esters of 12-36C di-acids and 12-32C alkanols. Amts. are 5-60 (pref. 20-40) wt.% (a), 0.01-5 (pref. 0.1-2) wt.% (b) and 35-94.99 (pref. 58-79.9) wt.% (c). USE/ADVANTAGE - The use of (I) as binder enables the prodn. of sintered metal or ceramic mouldings (III) with a great redn. in the time required to drive off the binder from the green compact, and with no deformation or cracking; binder (I) also ensures good powder bonding, with no sepn.. Also claimed is a process for producing (III), by mixing 50-90 (pref. 60-80) vol.% metal or ceramic powder (IV) with 10-50 (pref. 20-40) vol.% (I), injecting the mixt. into a mould and removing binder (I) by heating.