摘要:
Injection molding systems and methods useful for making microcellular foamed materials are provided as well as microcellular articles. Pressure drop rate and shear rate are important features in some embodiments, and the invention provides systems for controlling these parameters in an injection molding system. Another aspect involves an injection molding system including a nucleator that is upstream of a pressurized mold. Another aspect involves an extrusion system with the reciprocating screw for forming a single phase solution of non-nucleated blowing agent and polymeric material. Another aspect involves very thin walled microcellular material and very thin walled polymeric material. Another aspect provides a method for producing high weight reductions in very thin-walled parts with surfaces that have no noticeable differences from non-foamed parts.
摘要:
Injection molding systems and methods useful for making microcellular foamed materials are provided as well as microcellular articles. Pressure drop rate and shear rate are important features in some embodiments, and the invention provides systems for controlling these parameters in an injection molding system. Another aspect involves an injection molding system including a nucleator that is upstream of a pressurized mold. Another aspect involves an extrusion system with the reciprocating screw for forming a single phase solution of non-nucleated blowing agent and polymeric material. Another aspect involves very thin walled microcellular material and very thin walled polymeric material. Another aspect provides a method for producing high weight reductions in very thin-walled parts with surfaces that have no noticeable differences from non-foamed parts.
摘要:
Injection molding systems and methods useful for making microcellular foamed materials are provided as well as microcellular articles. Pressure drop rate and shear rate are important features in some embodiments, and the invention provides systems for controlling these parameters in an injection molding system. Another aspect involves an injection molding system including a nucleator that is upstream of a pressurized mold. Another aspect involves an extrusion system with the reciprocating screw for forming a single phase solution of non-nucleated blowing agent and polymeric material. Another aspect involves very thin walled microcellular material and very thin walled polymeric material. Another aspect provides a method for producing high weight reductions in very thin-walled parts with surfaces that have no noticeable differences from non-foamed parts.
摘要:
A microcellular injection blow molding system and method, and microcellular blow molded articles produced thereby, are described. The system is equipped to extrude microcellular material that changes in thickness, material density, or both in the machine direction while maintaining a constant pressure drop rate during nucleation just prior to extrusion, providing the ability to produce consistent uniform microcellular material independent of material thickness. The systems and methods are particularly useful in production of strong, thin-walled, non-liquid-permeable, opaque containers that do not contain reinforcing agent, chromophore, or residue of chemical blowing agent or chemical blowing agent by-product.
摘要:
The invention provides in-mold decorated articles and methods to form the articles. The in-mold decorated articles include a polymeric portion having a substrate material adhered to a surface of the polymeric portion. The substrate material may be, for example, a film or a fabric. In some embodiments, the polymeric portion may be a foam and, particularly, a microcellular polymeric material. The articles are formed by injecting a mixture of blowing agent and polymeric material into a mold cavity in which the substrate material is disposed, so that the substrate material is forced against a wall of the mold cavity. The blowing agent, which in certain preferred cases is a supercritical fluid, decreases the viscosity of the polymeric material and, therefore, enables reductions in injection pressures and temperatures. Reduced injection temperature and pressure may widen the processing window, increase flexibility in the selection of substrate materials, and can eliminate the need for a barrier layer that is sometimes used in conventional processes. The method may be used to produce a variety of in-mold decorated articles.
摘要:
The invention provides in-mold decorated articles and methods to form the articles. The in-mold decorated articles include a polymeric portion having a substrate material adhered to a surface of the polymeric portion. The substrate material may be, for example, a film or a fabric. In some embodiments, the polymeric portion may be a foam and, particularly, a microcellular polymeric material. The articles are formed by injecting a mixture of blowing agent and polymeric material into a mold cavity in which the substrate material is disposed, so that the substrate material is forced against a wall of the mold cavity. The blowing agent, which in certain preferred cases is a supercritical fluid, decreases the viscosity of the polymeric material and, therefore, enables reductions in injection pressures and temperatures. Reduced injection temperature and pressure may widen the processing window, increase flexibility in the selection of substrate materials, and can eliminate the need for a barrier layer that is sometimes used in conventional processes. The method may be used to produce a variety of in-mold decorated articles.
摘要:
An embrittlement-resistant polyolefin composition, including: (a) at least 80% by weight, based on the total weight of the polyolefin composition, of a crystalline polymer comprising either a propylene homopolymer having an isotactic index greater than 90 or a random copolymer of propylene and either ethylene or C.sub.4 -C.sub.10 1-olefins, (b) an elastomeric copolymer of ethylene and either propylene or butene-1, where the elastomeric copolymer is present in an amount sufficient to enhance the flexibility of the polyolefin composition, without adversely affecting the clarity of the polyolefin composition, and where the polyolefin composition has a heat distortion temperature of at least 60.degree. C. Optional components include a stabilizing amount of a hindered amine light stabilizer, an acid neutralizing agent, and a sorbitol-based compound. The composition may be used to manufacture medical articles and food packaging material which must be sterilized, either by irradiation or by autoclaving.