摘要:
Process for the production of foam boards having a minimum thickness of 20 mm and a cross-sectional area of at least 50 cm.sup.2 by extruding a mixture of the styrene polymer, from 1 to 10% by weight, based on the styrene polymer, of a blowing agent, wherein the blowing agent contains at least one ether from the group consisting of dimethyl ether, methyl ethyl ether and methyl vinyl ether.
摘要:
Extruded foam boards produced using halogen-free blowing agents from a styrene polymer thermoplastic matrix having a Vicat softening temperature VST B 50 of at most 100.degree. and a melt index MVI 200/5 of at least 5 ml/10 min are at least 20 mm, preferably more than 50 mm and in particular from 80 to 200 mm, thick. Preferred blowing agents for producing the foam boards are carbon dioxide alone, as well as mixtures of carbon dioxide and ethanol and/or dimethyl ether.
摘要:
Foam boards of high compressive strength are produced by extruding a mixture of a styrene polymer and from 5 to 16% by weight of a blowing agent which containsa) from 3 to 70% by weight of an alcohol or ketone having a boiling point of from 56.degree. to 100.degree. C.,b) from 0 to 50% by weight of carbon dioxide,c) from 0 to 88% by weight of a saturated C.sub.3 - to C.sub.5 -hydrocarbon,d) from 2 to 90% by weight of at least one fluorinated hydrocarbon which has a boiling point of from -30 .degree. to +30.degree. C.
摘要:
Foam sheets of high heat distortion resistance contain a) from 80 to 99% by weight of a styrene polymer and b) from 1 to 20% by weight of poly-1,4-phenylene sulfide, and, if desired, conventional additives and are produced by extrusion using a low-boiling blowing agent.
摘要:
Foam sheets of high compressive strength are produced by extruding a mixture of a styrene polymer and from 5 to 16% by weight of a blowing agent mixture containinga) from 3 to 70% by weight of an alcohol or ketone having a boiling point of from 56.degree. to 100.degree. C.,b) from 5 to 50% by weight of carbon dioxide andc) from 0 to 90% by weight of a saturated C.sub.3 - to C.sub.5 -hydrocarbon and/or of a hydrogen-containing chlorofluorocarbon or fluorinated hydrocarbon boiling at from -30.degree. to +30.degree. C.
摘要:
Foam sheets of high heat distortion resistance contain a) from 80 to 99% by weight of a styrene polymer and b) from 1 to 20% by weight of poly(2,6-dimethyl-1,4-phenylene oxide), and, if desired, conventional additives and are produced by extrusion using a low-boiling blowing agent.
摘要:
Foams having high compressive strength are obtained by extrusion of a mixture of a styrene polymer and from 3 to 9% by weight of a blowing agent consisting of from 80 to 100% by weight of CO.sub.2 and from 0 to 20% by weight of one or more halohydrocarbons or hydrocarbons which are gaseous at room temperature, the mixture being extruded into a zone under from 0.1 to 2 bar gage pressure and the foam being allowed to stabilize under this pressure.
摘要:
Closed-celled foams of high compressive strength are obtained by extruding a mixture of a styrene polymer and from 8 to 16% by weight of a blowing agent mixture containing from 2 to 20% by weight of ethyl chloride, from 2 to 20% by weight of carbon dioxide, from 20 to 80% by weight of dichlorodifluoromethane and from 10 to 60% by weight of monochlorodifluoromethane.
摘要:
Fine-celled foams are produced by a process in which a styrene polymer is melted, the melt is mixed with a volatile blowing agent and a nucleating agent under superatmospheric pressure, the mixture is let down to atmospheric pressure, and the foam is cooled. The nucleating agent employed comprises from 0.02 to 2% by weight of the calcium salt of a long-chain fatty acid, and from 0.01 to 1% by weight of a finely divided, inorganic substance which is insoluble in the styrene polymer, a mixture of calcium stearate and magnesium oxide being preferred.
摘要:
In the pneumatic pressing of textile strands in a drafting frame the pressure in the pressure line is monitored by a pressure sensor and/or a flowmeter and used to control a value between the pressure source and that pressure line. According to the invention a disturbance signal is outputted when the pressure in the line drops below a threshold, the control signal for the valve exceeds a threshold, the displacement of the value member exceeds a certain level and the flow rate exceeds a value so as to indicate leakage beyond a tolerance level.