Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1994-11-22
1995-11-07
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521 56, 521 79, 521 81, 521147, C08J 916
Patent
active
054648815
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to expandable styrene polymers of high heat resistance. In particular, the invention relates to expandable styrene polymers of this type which contain styrene-methacrylamide copolymers based on certain N-substituted methacrylamides, to a preferred process for their preparation, and to the foams obtained using these polymers.
Expandable styrene polymers of high heat resistance are disclosed in EP-A 294 783, EP-A 383 133, EP-A 419 966 and U.S. Pat. No. 4,298,703. These polymers contain poly-1,4-phenylene ether, poly-1,4-phenylene sulfide or copolymers of styrene with maleic acid, maleic anhydride or N-substituted maleimide.
However, these known expandable styrene polymers have some disadvantages. For example, copolymers of styrene with N-substituted maleimide can only be foamed by means of an extruder. Our own experiments have shown that the copolymerization of styrene with maleimide in aqueous suspension in the presence of a blowing agent does not give expandable polymers. If poly-2,6-dimethyl-1,4-phenylene ether (PPE) is used, the moldings obtained have a tendency to gradually yellow. In addition, the preparation and processing of polystyrene/PPE blends or interpolymers to give expandable, spherical beads is relatively complex.
JP-A 63/273 612 discloses a copolymer which comprises methacrylamide, styrene derivatives and acrylonitrile. The copolymer is said to have improved properties with respect to fluidity, transparency, heat resistance, mechanical resistance and yellowing resistance and can be used to produce moldings or foams.
It is an object of the present invention to provide an expandable styrene polymer which does not have the outlined disadvantages.
We have found that, surprisingly, this object is achieved by an expandable styrene polymer comprising than b) containing at least 50% by weight of copolymerized styrene, comprising from 0.5 to 50% by weight of at least one copolymerized N-substituted methacrylamide of the formula I ##STR2## where R.sup.1 and R.sup.2 are identical or different and are hydrogen, C.sub.1 - to C.sub.15 -alkyl, C.sub.6 - to C.sub.16 -cycloalkyl or C.sub.6 - to C.sub.20 -aryl, it being possible, if R.sup.1 and R.sup.2 contain at least 2 carbon atoms, for at least 2 carbon atoms to be linked via hetero atoms, and C.sub.3 - to C.sub.16 -hydrocarbon and/or carbon dioxide as blowing agent.
The present invention also provides a process for the preparation of an expandable styrene polymer of this type, which comprises polymerizing a styrene solution of at least one substituted methacrylamide of the formula I ##STR3## where R.sup.1 and R.sup.2 are identical or different and are hydrogen, C.sub.1 - to C.sub.15 -alkyl, C.sub.6 - to C.sub.16 -cycloalkyl or C.sub.6 - to C.sub.20 -aryl, it being possible, if R.sup.1 and R.sup.2 contain at least 2 carbon atoms, for at least 2 carbon atoms to be linked via hetero atoms, and, if desired, a styrene polymer or styrene copolymer containing at least 50% by weight of copolymerized styrene, in aqueous suspension and adding the blowing agent during or after the polymerization.
The present invention furthermore provides a foam having a density of from 0.01 to 0.2 g/cm.sup.3, comprising than b) containing at least 50% by weight of copolymerized styrene, comprising from 0.5 to 50% by weight of at least one copolymerized N-substituted methacrylamide of the formula I ##STR4## where R.sup.1 and R.sup.2 are identical or different and are hydrogen, C.sub.1 - to C.sub.15 -alkyl, C.sub.6 - to C.sub.16 -cycloalkyl or C.sub.6 - to C.sub.20 -aryl, it being possible, if R.sup.1 and R.sup.2 contain at least 2 carbon atoms, for at least 2 carbon atoms to be linked via hetero atoms.
Suitable styrene polymers a) are polystyrene and copolymers containing at least 50% by weight of copolymerized styrene. Examples of suitable comonomers are .alpha.-methylstyrene, ring-halogenated styrenes, ring-alkylated styrenes, acrylonitrile, esters of (meth)acrylic acid with alcohols having 1 to 8 carbon atoms, N-vinyl compounds, such as N-vinylcarbaz
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Derwent Abst. JP 1 319 546.
Besecke Siegmund
Brudermueller Martin
Deckers Andreas
Guentherberg Norbert
Henn Rolf
BASF - Aktiengesellschaft
Foelak Morton
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