Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1998-05-12
2000-02-08
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C08K 515
Patent
active
060229152
DESCRIPTION:
BRIEF SUMMARY
The invention relates to thermoplastic molding compositions and, in particular, to a method for reducing the formation of residual monomers on thermal stress and shearing of the molding compositions. WO 90/07547 discloses stabilizer mixtures of .alpha.-tocopherol (vitamin E) and glycerol mono-, di- and/or triesters of saturated or unsaturated fatty acids for stabilizing thermoplastics such as polyvinyl chloride, styrene polymers, polyamides, polycarbonate, polyesters and polyolefins. J5 6028-228 and J5 0110-442 describe the stabilization of, inter alia, polyethylene, polypropylene and PVC with .alpha.-tocopherol. J5 4055-043 and J6 3137-941-A mention as stabilizer for polyolefins vitamin E and a compound of the phosphite or phosphonite type. Furthermore, J5 8002-337 discloses a method for preventing the formation of carcinogenic nitrosamines in natural or synthetic rubber by incorporating vitamin E, inter alia, into the latter.
EP-A-0 384 472 discloses a composition comprising a thermoplastic, a light stabilizer and vitamin E as packing material for light-sensitive materials, and ABS is one of the thermoplastics mentioned.
Acrylonitrile-containing polymers are prone, especially on thermal stress or shearing, to form acrylonitrile monomers. This is a problem because acrylonitrile is classified as a group IIIA2 carcinogen (cf. acrylonitrile, data sheet M 016, 11/90, published by the Berufsgenossenschaft der Chemischen Industrie).
It was therefore the object of the present invention to develop molding compositions of acrylonitrile-containing polymers with which the formation of residual monomers on thermal stress and shearing is reduced. It has been found, surprisingly, that this technical problem can be solved by a thermoplastic molding composition of acrylonitrile-containing polymers and .alpha.-tocopherol. It has been found in particular that the formation of residual monomers can be reduced when acrylonitrile-containing polymers are subjected to thermal stress in the presence of .alpha.-tocopherol.
The present invention thus relates to thermoplastic molding compositions comprising acrylonitrile-containing polymer, and
The invention furthermore relates to a method for reducing the formation of residual monomers on thermal stress and shearing of the molding compositions, which comprises adding 0.005-2% by weight, based on A+B, of .alpha.-tocopherol before, during or after the polymerization, but before the thermal stress or shearing. The invention furthermore relates to the use of the molding compositions according to the invention for producing moldings and to these moldings. The subject-matter of the invention and preferred embodiments thereof are defined in the claims. Component A comprises an acrylonitrile-containing polymer, preferably polyacrylonitrile, an acrylonitrile-styrene copolymer or a copolymer of acrylonitrile/styrene derivatives or of acrylonitrile and methyl methacrylate. Examples of suitable styrene derivatives are nuclear-substituted styrenes and styrenes substituted on the double bond, such as, for example, .alpha.-methylstyrene. An .alpha.-methylstyrene/acrylonitrile copolymer is most preferred.
In a preferred embodiment, the acrylonitrile-containing polymers contain other polymers such as, for example, rubbers such as polybutadiene or poly(butyl acrylates), which can also be grafted with other monomers, eg. with polystyrene/acrylonitrile. The acrylonitrile-containing polymers may also be mixed with polycarbonate.
The molding compositions according to the invention comprise 98-99.995, preferably 98.5-99.9, particularly preferably 99.5-99.93, in each case % by weight based on A+B, of the acrylonitrile-containing polymer.
.alpha.-Tocopherol is used as component B.
The amount of component B is 0.005-2, preferably 0.01-1.5, particularly preferably 0.02-0.5, in each case in % by weight based on A+B. In a preferred embodiment, component B is added before or during the preparation of the acrylonitrile-containing polymer. In another preferred embodiment, component B is added after the polymeriz
REFERENCES:
patent: 4806580 (1989-02-01), Bock et al.
patent: 5629363 (1997-05-01), Abber
patent: 5747162 (1998-05-01), Temple
patent: 5747568 (1998-05-01), Fischer
Derwent Abst. J5 6028-228.
Derwent Abst J5 0110-442.
Abst. J5 4055-043.
Derwent Abst. J6 3137-941.
Derwent Abst. J5 8002-337.
Abst. J5 7002-337.
Fischer Wolfgang
Gunesin Binnur
Guntherberg Norbert
Mc Kee Graham Edmund
Ticktin Anton
BASF - Aktiengesellschaft
Michl Paul R.
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