Process and mold for molding foamed plastic articles

Patent · Tue Oct 30 04:00:00 EST 1984

OSTI ID:5813894

Baumrucker, E J

A method for forming foamed plastic articles which includes the steps of closing a mold; prepressurizing the mold cavity with gas to prevent premature diffusion of blowing gas from the material injected into the cavity; injecting a short shot of molten synthetic resin material containing a blowing agent into the cavity; venting a portion of the prepressurization gas during the injection step; and venting the remaining prepressurization gas from the mold cavity to a vacuum chamber means to allow expansion of the injected foamable resin material within the mold cavity, the vacuum drawing the resin material throughout the mold cavity. In addition, the vacuum chamber is coupled to the mold cavity through plural spaced passageways so that the vacuum is drawn at various locations throughout the cavity to thereby enhance the complete filling of the cavity with the injected material as it expands. The mold is vented following the injection step automatically at the expiration of a predetermined time following the closing of a nozzle of the injection apparatus. A mold for carrying out the process includes improved gas flow means for delivering gas to and venting gas from the mold cavity. The mold also includes improved sealing means for sealing the mold to maintain it in a pressurized state as desired.

• Assignee: Cashiers Plastics
• Patent Number(s): US 4479914
• OSTI ID: 5813894
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360401* -- Polymers & Plastics-- Preparation & Fabrication-- (-1987)
CASTING MOLDS
COLLOIDS
DESIGN
DISPERSIONS
FABRICATION
FOAMS
MOLDING
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTIC FOAMS
POLYMERS
PRESSURIZING
RESINS