INJECTION MOLDING METHOD

• Main Authors: KOGA SHIGEHIRO, IMAI KAZUYOSHI, SHIYUDOU KAZUMICHI, INABA KAZUO, YAMADA TETSUYA, YAMANOUCHI MASAFUMI
• Format: Patent
• Language: English
• Published: 06.07.1985
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

PURPOSE:To obtain a lightweight soft polyvinyl chloride molded anticle with excellent wear-resistant property and fine external appearance by a method wherein soft non-crosslinked polyvinyl chloride composition blended with lightweight filler is injection-molded by employing a pinpoint gate under specified conditions. CONSTITUTION:Lightweight polyvinyl chloride composition employing PVC (polyvinyl chloride), the mean degree of polymerization of which is 400-4,000, consists in blending 100pts.wt. of PVC with 30-150pts.wt. of plasticizer and 5- 100pts.wt. of lightweight filler, the specific gravity of which is 0.8 or less, the particle diameter of which is 300mum or less and the compression strength of which is 70kg/cm or above. Said composition is mixed with stabilizer and another additives in a mixer and, after that, filled through a pinpoint gate, the gate crosssectional area of which is 0.5-2mm. and the length of which 1-5mm., into a cavity at the linear speed of molten resin of 5X10 -2X10 cm/sec in order to obtain a molded part with the minimum thickness of 2mm..