Pre-expanded polypropylene resin particles, in-mold foam molded product of polypropylene resin, and method for manufacturing same
AssigneeKaneka Corporation
InventorAkihiro Itoi
Life of this patent
Estimating the term…
Abstract
Provided are pre-expanded polypropylene resin particles having a dimensional expansion coefficient of 1.5% or more determined with a thermomechanical analyzer at a constant compressive load of 1 mg during heating from 30° C. to 100° C. at a temperature increase rate of 10° C./min. Using the pre-expanded polypropylene resin particles can yield an in-mold foam molded product of polypropylene resin having few wrinkles and small dimensional shrinkage without pretreatment such as internal pressure application or compression packing during packing the pre-expanded particles in a mold for in-mold foam molding.
Claims4
Pre-expanded polypropylene resin particles comprising a polypropylene resin as a substrate resin,
- the resin particles having an average particle weight of 3 mg/particle or less, and
- the pre-expanded particles having a dimensional expansion coefficient of 1.5% or more determined with a thermomechanical analyzer at a constant compressive load of 0.1 g during heating from 30° C. to 100° C. at a temperature increase rate of 10° C./min.
A method for manufacturing pre-expanded polypropylene resin particles, the method comprising:
- dispersing polypropylene resin particles including a polypropylene resin composition in a dispersion medium in the presence of a foaming agent, heating the dispersion mixture under pressure, and discharging the dispersion mixture into a low pressure area, thereby affording pre-expanded polypropylene resin particles;
- and
- heating the pre-expanded polypropylene resin particles with steam at 0.04 MPa (G) or more and 0.15 MPa (G) or less for 30 seconds or more.
A method for manufacturing pre-expanded polypropylene resin particles, the method comprising:
- dispersing polypropylene resin particles including a polypropylene resin composition in an aqueous dispersion medium in the presence of a foaming agent, heating the dispersion mixture under pressure, and discharging the dispersion mixture into a low pressure area, thereby affording pre-expanded polypropylene resin particles;
- pressurizing the pre-expanded polypropylene resin particles with an inorganic gas to make the pressure in the pre-expanded polypropylene resin particles higher than atmospheric pressure;
- and then
- heating the pre-expanded polypropylene resin particles with steam at 0.04 MPa (G) or more and 0.15 MPa (G) or less for 90 seconds or more.
Dependencies are inferred from the claim text.