Methods of forming an article from a molten plastic composition comprising a polymer and a blowing agent. The methods include injecting the molten plastic composition into a mould, allowing the plastic composition to form a first solid skin adjacent to an in contact with a first cavity-forming surface of the mould and a second solid skin adjacent to and in contact with a second cavity-forming surface of the mould, and then opening the mould before the molten plastic composition between the first and second solid skins in at least one portion of the circumference of a region of the mould cavity defining an annular cross-section of the cavity has solidified.

An injection molding machine for foam molding includes: a heating cylinder; a screw disposed in the heating cylinder; and a plurality of inlet portions provided in the heating cylinder and configured to introduce inert gas. An inside of the heating cylinder includes a starvation section on an upstream side in which a pressure of the resin is decreased, and the inert gas from the plurality of inlet portions being to be supplied in the starvation section. Each of the plurality of inlet portions is provided with a check valve or an opening and closing mechanism. A product P×N of an interval P of the plurality of inlet portions and a number N of the inlet portions is 0.5H or more and 1.71H or less with respect to a length H of the starvation section.

An injection molded article obtained by injection molding a thermoplastic resin composition comprising 100 parts by mass of a thermoplastic resin and 50 parts by mass or less of at least one of a filler and a colored metallic pigment, wherein at least one weld exists, and a long diameter of 95% by mass or more of the filler existing within a cross-sectional depth of 50 μm or less from a surface of the weld is parallel to the surface of the weld.

A kneading apparatus for a thermoplastic resin, includes: a plasticizing cylinder which has a high pressure kneading zone and a pressure reduction zone; a screw in the plasticizing cylinder; a downstream side seal mechanism which shuts off communication between the high pressure kneading zone and the pressure reduction zone; and a pressure reduction zone pressure adjusting mechanism which is connected to the pressure reduction zone and which controls a pressure of the pressure reduction zone so that the pressure is not less than an atmospheric pressure and the pressure is not more than a maximum pressure of the high pressure kneading zone that is achieved when kneading a molten resin with a pressurized fluid, when the downstream side seal mechanism shuts off the communication between the high pressure kneading zone and the pressure reduction zone.

The method for manufacturing a foamed product uses a manufacturing apparatus having a plasticizing cylinder in which an introduction port for introducing a physical blowing agent into a starvation zone is formed, and an introduction speed adjustment container connected to the introduction port, wherein the manufacturing method comprises: turning a thermoplastic resin into a molten resin; introducing the physical blowing agent at a predetermined pressure into the starvation zone through the introduction speed adjustment container and maintaining the starvation zone at a predetermined pressure; setting the molten resin to a starved state; bringing the molten resin in the starved state and the pressurized fluid into contact with each other; and molding the molten resin into a foamed product. The maximum value of the inner diameter of the introduction speed adjustment container is larger than the inner diameter of the introduction port.

Method of forming an article from a molten plastic composition including a polymer and a blowing agent. The method provides that during an injecting step (c) and a packing step (d), the injection pressure and the packing pressure, respectively, are maintained above a minimum pressure threshold in at least one second region of the cavity to maintain the physical blowing agent as a gas dissolved in the polymer so that substantially no gas bubbles are formed in the at least one second region, during a mould opening step (e), at least some of the molten plastic composition is exposed to an external pressure lower than a minimum pressure threshold to form in the article at least one first portion having expanded cellular foam formed from the plastic composition, and prior to the opening step (e), the plastic composition in the at least one second region of the cavity has been cooled so as to be fully solidified to form in the article at least one second portion having a substantially homogeneous, solid phase, unexpanded plastic composition

Method of forming an article from a molten plastic composition including a polymer and a blowing agent. The method provides that during an injecting step (c) and a packing step (d), the injection pressure and the packing pressure, respectively, are maintained above a minimum pressure threshold in at least one second region of the cavity to maintain the physical blowing agent as a gas dissolved in the polymer so that substantially no gas bubbles are formed in the at least one second region, during a mould opening step (e), at least some of the molten plastic composition is exposed to an external pressure lower than a minimum pressure threshold to form in the article at least one first portion having expanded cellular foam formed from the plastic composition, and prior to the opening step (e), the plastic composition in the at least one second region of the cavity has been cooled so as to be fully solidified to form in the article at least one second portion having a substantially homogeneous, solid phase, unexpanded plastic composition.

The disclosure is directed to a solid part, and a device and process of making the solid part. The process includes introducing a glass fiber filled polymeric material to a hopper of an injection molding machine, where the glass fibers have a pre-molding length, melting the glass fiber filled polymeric material to form a melt in a plasticizing unit, pressurizing the plasticizing unit of the injection molding machine with a blowing agent, dissolving the blowing agent into the melt, injecting the melt into a mold cavity up to 100% of volume, and forming the solid part.

The disclosure provides an injection molding apparatus, including a mold unit, an injecting unit, and a counter pressure unit. The mold unit is adapted to provide a first cavity and a second cavity. The injecting unit is adapted to inject a first material into the first cavity to form a first molded object. The second cavity is adapted to accommodate the first molded object. The injecting unit is adapted to inject a second material into the second cavity to form a second molded object, such that the first molded object and the second molded object in the second cavity are combined. The second material is a foaming material. And the counter pressure unit is adapted to provide gas into the second cavity to increase the pressure in the second cavity.

Methods of forming an article from a molten plastic composition comprising a polymer and a blowing agent. The methods include injecting the molten plastic composition into a mould, allowing the plastic composition to form a first solid skin adjacent to an in contact with a first cavity-forming surface of the mould and a second solid skin adjacent to and in contact with a second cavity-forming surface of the mould, and then opening the mould before the molten plastic composition between the first and second solid skins in at least one portion of the circumference of a region of the mould cavity defining an annular cross-section of the cavity has solidified.