US 12,070,882 B2
Foaming technology in long glass fiber filled materials
Angel Yanev, Maastricht (NL); Marnik Vaes, Zonhoven (BE); and Warden Schijve, Sittard (NL)
Assigned to SABIC GLOBAL TECHNOLOGIES B.V., Bergen op Zoom (NL)
Filed by SABIC GLOBAL TECHNOLOGIES B.V., Bergen op Zoom (NL)
Filed on Jan. 17, 2020, as Appl. No. 16/745,505.
Application 16/745,505 is a division of application No. 15/304,059, abandoned, previously published as PCT/IB2015/052794, filed on Apr. 16, 2015.
Claims priority of provisional application 61/980,228, filed on Apr. 16, 2014.
Prior Publication US 2020/0147843 A1, May 14, 2020
Int. Cl. B29C 45/00 (2006.01); B29C 44/42 (2006.01); B29C 45/17 (2006.01); B29C 45/18 (2006.01); B29K 105/04 (2006.01); B29K 105/12 (2006.01); B29K 309/08 (2006.01); B29K 509/08 (2006.01)
CPC B29C 45/0005 (2013.01) [B29C 44/42 (2013.01); B29C 45/18 (2013.01); B29C 2045/1722 (2013.01); B29K 2105/04 (2013.01); B29K 2105/12 (2013.01); B29K 2309/08 (2013.01); B29K 2509/08 (2013.01)] 16 Claims
 
1. A method of making a foamed part, comprising:
introducing a glass fiber filled polymeric material to a hopper of an injection molding machine, wherein the glass fibers have a pre-molding length;
melting the glass fiber filled polymeric material to form a melt;
pressurizing a plasticizing unit of the injection molding machine with a blowing agent, wherein a seal is located between a rotating part and a fixed part of the plasticizing unit, the seal between a screw shaft and a plasticizing cylinder at an end of the screw shaft of the plasticizing unit to prevent loss of blowing agent;
sealing the plasticizing unit with an airlock mounted between the plasticizing cylinder of the injection molding machine and the hopper to homogenize the melt and the blowing agent;
increasing a pressure of the blowing agent and increasing a back pressure of the injection molding machine to homogenize the melt and the blowing agent, wherein the screw shaft is in a screw and is under a pressure with a relatively flat pressure profile to prevent breakage of the glass fibers; and
forming the foamed part;
wherein a post-molding length of the glass fibers in the foamed part is greater than or equal to a post-molding length of glass fibers in a similarly dimensioned foamed part made without pressurizing the plasticizing unit due to glass fiber breakage caused by shear stress during homogenizing of the melt and the blowing agent.