Method for making articles by cold compaction molding and the molded articles prepared thereby
View Patent ↗A method for making an article by cold compaction molding. The method comprises compacting a resin composition comprising high molecular weight and ultra high molecular weight polyethylene (HMW-PE and UHMW-PE, respectively) homopolymer, copolymer, and/or blend and an inorganic acid scavenger at a temperature below the softening temperature of the composition. An article prepared in accordance with the claimed method shows lower corrosion test data compared to articles prepared from virgin HMW-PE and UHMW-PE, and an improved cold compaction strength compared to articles prepared using resins containing metal soaps.
1. A method for making an article by cold compaction molding, wherein the method comprises cold compacting a resin composition comprising a HMW-PE or an UHMW-PE and an inorganic acid scavenger at a temperature below the melting temperature of the polyethylene to form the article.
2. The method according to claim 1 , further comprising sintering the article at an elevated temperature after compaction.
3. The method according to claim 1 , wherein the molecular weight of the polyethylene is above about 200,000.
4. The method according to claim 1 , wherein the resin composition is subjected to pressures in the range of about 50 psi to about 6,000 psi during compaction.
5. The method according to claim 1 , wherein the compaction temperature is about 0-120° C.
6. The method according to claim 1 , wherein the acid scavenger is selected from the group consisting of metal oxides, metal carbonates, silicates and mixtures thereof.
7. The method according to claim 1 , wherein the concentration of the acid scavenger in the resin composition is in the range of about 100-2500 ppm.
8. The method according to claim 1 , wherein the resin composition is in the form of a powder before compaction.
9. A molded article prepared in accordance with the method of any one of claims 1 - 8 .
10. The molded article according to claim 9 , wherein the article is characterized by an improved cold compaction strength.
11. The molded article according to claim 10 , wherein the cold compaction strength of the article is not less than about 75% of the cold compaction strength of an article prepared from virgin polyethylene.
12. The molded article according to claim 10 , wherein the cold compaction strength of the article is not less than about 90% of the cold compaction strength of an article prepared from virgin polyethylene.