摘要:
A process for freezing a plastic molding machine involving: (a) providing a freezable compound containing: (i) from 20 to 45% by weight of at least one homopolymer or copolymer selected from the group consisting of an ester of methacrylic acid with a monohydric alcohol having from 1 to 4 carbon atoms, a graft polymer of an ester of methacrylic acid with a monohydric alcohol having from 1 to 4 carbon atoms, an ethylene/vinyl acetate copolymer, a graft copolymer of an ethylene/vinyl acetate copolymer, and mixtures thereof; (ii) from 45 to 75% by weight of chalk having a particle size of from 2 to 150 microns; and (iii) from 0.01 to 10% by weight of at least one freezing agent selected from the group consisting of a lubricant having a volatility of less than 0.2% by weight, a release agent having a volatility of less than 0.2% by weight, and mixtures thereof; and (b) charging the plastic molding machine with the freezable compound prior to turning of the plastic molding machine.
摘要:
Stabilizers for chlorine-containing olefin polymers containing Ca complexes of 1,3-diketones, hydrocarbon waxes and esters and/or partial esters of saturated, straight-chain C.sub.12 -C.sub.34 monocarboxylic acids, in conjunction with zinc salts of saturated, straight-chain C.sub.8 -C.sub.22 monocarboxylic acids and esters of phosphorous acid, provide the polymers with excellent properties in regard to processibility and temperature stability.
摘要:
A process for producing a shaped body includes the steps of producing a molding composition, plasticization of the molding composition in an extruder and discharge through a slit die, introduction of the green body into a smoothing calender, smoothing the green body through the use of one or more smoothing processes, chemical and/or thermal binder removal and sintering. The continuous process preferably makes it possible to economically produce sheet products having a high surface quality.
摘要:
A process is described in which hollow spheres or hollow-sphere composites (moldings) having high-strength walls are produced. Additional layers are applied to metallized spherical lightweight particles having a core of foamed polymer. In order to increase the strength of the wall of the spherical particle and the strength of the molding, metallized lightweight spherical particles having a metal wall thickness of 5 to 20 microns are treated (coated) with a dispersion of particulate metal or metal oxide or particulate ceramic or refractory material, the lightweight spherical particles coated in a thickness from 15 to 500 microns are dried, the dried particles are heated to a temperature of about 400.degree. C. to effect a pyrolysis of the polymer core, and the particles are subsequently sintered at a temperature from 900.degree. to 1400.degree. C.
摘要:
The process of the invention for producing highly porous shaped sintered parts comprises the foaming of thermoplastically flowable molding compositions in the temperature range 80-130° C. An important feature of the process is the use of expandable polystyrene as blowing agent, and also of binder components matched thereto. During foaming, intrinsically closed, cell-like polystyrene foam particles are formed, which allows the manufacture of mechanically strong shaped sintered bodies having a proportion of pores of up to 85% by volume combined with high homogeneity of the pore diameter. The process is employed for the manufacture of open- or closed-porosity shaped sintered ceramic and/or metallic bodies.
摘要:
Metallic or ceramic hollow spheres are produced by applying a solid layer to a substantially spherical particle of foamed polymer and the coated polymer cores are pyrolyzed with formation of vapor. In order to permit an economical production of the hollow spheres and a wide selection from a wide range of metallic or ceramic materials, the particles consisting of foamed polymer are treated in a state of agitation with an aqueous suspension which contains dissolved or suspended binder and metallic and/or ceramic powder particles, whereby a coating is formed on said polymer particles. The coating is dried, the polymer particles and least part of the binder are subsequently pyrolyzed at temperatures from 400.degree. to 500.degree. C. with formation of vapor while they are agitated and the resulting metallic and/or ceramic hollow spheres are sintered at temperatures from 1000.degree. to 1500.degree. C. while they are agitated.
摘要:
A substituted melamine additive being a mixture of the formula ##STR1## wherein the six R substituents represent the following: (a) 0 to 3 are hydrogen;(b) 1 to 5 are R'--OCH.sub.2 --, wherein R' is a member selected from the group consisting of hydrogen and alkyl having from 1 to 4 carbon atoms;(c) 1 to 4 are substituents selected from the group consisting of R.sup.2 OCH.sub.2 --, R.sup.2 COOCH.sub.2 --, R.sup.2 CONHCH.sub.2 --, mixtures thereof, wherein R.sup.2 is a hydrocarbon group having 8 to 28 carbon atoms, and(d) 0 to 2 are substituents selected from the group consisting of Z--CH.sub.2 --O--CH.sub.2 -- and Z--CH.sub.2 --, wherein Z is a melamine group of the formula ##STR2## The substituted melamine additives are useful as additives in molding compositions based on thermosetting condensation resins to improve the moldability of the composition.