Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-01-29
1999-11-16
Nutter, Nathan M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525182, 525183, 525184, 525185, C08L 7500, C08L 7700, C08L 7702, C08L 7712
Patent
active
059860065
DESCRIPTION:
BRIEF SUMMARY
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a method of using a homo- or copolymers A composed of ##STR3## A.sub.2) 0-60% by weight of monomers of the general formula II ##STR4## and A.sub.3) 0-10% by weight of further monomers capable of free radical polymerization, 100% and hydrogen or C.sub.1 -C.sub.4 -alkyl, and each being hydrogen or C.sub.1 -C.sub.4 -alkyl, R.sub.1, R.sup.2 and R.sup.3 and from the group consisting of R.sup.4, R.sup.5 and R.sup.6 are hydrogen, and amino-containing thermoplastic polymers.
The present invention furthermore relates to thermoplastic polyamide molding materials which contain the novel branching agents, processes for the preparation of the molding materials, their use for the production of moldings of all types and the moldings obtainable thereby.
BACKGROUND OF THE INVENTION
Polyacrylic acids and polymethacrylic acids have long been known and are commercially available as, inter alia, Sokalan.RTM. (BASF AG). These polymers are usually used as additives for reduced-phosphorus and phosphate-free detergents and cleaning agents or as dispersants for solids (for example for preventing coatings in water treatment).
Suitable polymer compositions which can be used for the production of hollow articles by extrusion blow molding require, inter alia, high molecular weights in the case of polyamides.
In blow molding, a tube of polymer melt is generally extruded and is suspended between the two half-shells of the opened mold. The mold is then closed and the polymer tube is pressed against the mold by means of internal gas pressure, cooled and removed from the mold.
In this processing, it is essential that the polymer tube does not tear during extrusion in the periods when it is freely suspended between the molds, so that the molding process can be completed. It is also desirable that the tube does not sag, since this results in smaller wall thicknesses in the upper half and larger wall thicknesses in the lower half. Hollow articles having different wall thicknesses are unsuitable for use since the strength is as a rule limited by the point having the smallest wall thickness.
Particularly problematic is the danger of breaking of the melt or sagging in the case of glass fiber-reinforced polymer melts, since these have a high density (and hence a high tensile force on the upper part of the polymer tube) and at the same time the maximum extensibility of the polymer melt required to break is smaller in the case of these reinforced materials.
Both factors are governed by the melt rigidity, which depends primarily on the melt viscosity. What would be ideal is a high melt viscosity with little shearing--ie. after extrusion--but a low melt viscosity under a steep shear gradient--ie. in the processing extruder.
DESCRIPTION OF THE RELATED ART
This high melt viscosity can be achieved, inter alia, by compounding, for example, polyamides, in particular with the desired additives, in an extruder and then subjecting them to a solid-phase thermal aftertreatment (heating process) until the desired molecular weight has been reached. This process is disclosed, for example, in EP-A 589 349. The disadvantage of this process is the long reaction time, ie. the process is very time-consuming and therefore expensive.
Another process for achieving high melt viscosities comprises compounding with a highly reactive branching agent, as disclosed in EP-A 495 363, EP-A 495 368, EP-A 452 305 and EP-A 452 306. However, the styrene/maleic anhydride copolymers used exhibit poor dispersing in the polymer, so that very greatly fluctuating viscosities are present from granular particle to granular particle and lead to poor processability and defective blow molded articles.
A further problem is that polyamide fibers are produced in considerable amounts from polyamides whose molecular weight is below that which is usual for industrial molding materials. Polyamides having viscosity numbers of 115-140 ml/g are used, whereas viscosity numbers of >135 ml/g are required for industrial molding material
REFERENCES:
patent: 4554320 (1985-11-01), Reimann et al.
patent: 4818793 (1989-04-01), Matthies et al.
patent: 4900788 (1990-02-01), Subramanian
patent: 5003009 (1991-03-01), Matthies et al.
Gluck Alexander
Gotz Walter
Ley Gregor
BASF Aktiengsellschaft
Nutter Nathan M.
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