Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-06-05
1999-03-30
Warzel, Mark L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 66, 525 67, 525 69, 525 70, 525 71, 525 77, 525 80, 525 85, 525 86, 525307, 525309, C08L 5100
Patent
active
058891110
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to particulate graft polymers which are suitable for improving the quality of macromolecular base materials B and consist of mean particle diameter of from 1 to 100 .mu.m, and P.sub.a which is compatible or partly compatible with the base material B.
The present invention furthermore relates to the preparation of these graft polymers, their use for improving the quality of macromolecular base material B and mixtures of these graft polymers and the base materials and moldings produced therefrom.
It is generally known that the impact strength of nonresilient polymers can be improved by adding elastomeric polymers. In such blends, the nonresilient base material, which is also referred to as the matrix, forms a continuum in which the elastomeric particles are incorporated in the form of discrete particles.
Since the elastomeric polymer is often not compatible with the base polymer and is therefore difficult to incorporate in the base polymer, the rubber is surrounded in its preparation, in a manner also generally known, with a graft shell whose composition corresponds to that of the base polymer or which is compatible with the base polymer. This further improves the processing properties and performance characteristics of the toughened blend.
As a rule, the elastomeric graft polymers are prepared by emulsion polymerization. This process gives very finely divided polymers having a mean particle diameter of from 0.1 to less than 1 .mu.m.
However, this material gives only molding materials having high surface gloss. Frequently, however, dull moldings are desirable, so that dulling agents, such as silica gel or chalk, must be concomitantly used, although they have an adverse effect on the mechanical properties of the molding materials and of the moldings.
EP-A 269 324 discloses graft polymers having a relatively large particle diameter and comprising an elastomeric core polymer and an outer graft shell of a polymer which is compatible with the abovementioned nonresilient base material. Although molding materials containing these refracting particles have a dull surface, the process for the preparation of the particles is extremely inconvenient. In this process, the polymer particles of the grafting core which have initially formed in the emulsion polymerization are swollen with freshly added monomer, after which the polymerization is continued. This process can be repeated until the desired particle size is reached. Finally, these particles are provided with the graft shell which makes them compatible for mixing with the matrix polymer.
Furthermore, the preparation of the elastomeric particles by the emulsion polymerization process has in general the disadvantage that some of the emulsifiers required for this purpose remain in the polymer and are exuded from the moldings produced therefrom, with formation of undesirable coatings.
It is an object of the present invention to remedy the deficiencies described. It is a particular object of the present invention to provide elastomeric particulate graft polymers which make it possible to increase the impact strength of nonresilient polymers and at the same time perform the function of dulling agents.
We have found that these objects are achieved by the elastomeric particulate graft polymers defined at the outset.
We have also found a process for the preparation of these graft polymers, their use as components for blends with macromolecular base materials, such blends themselves and moldings comprising such blends.
The novel graft polymers are preferably obtained as follows: the liquid monomer or liquid monomer mixture M.sub.K which is to be polymerized to give the core polymer P.sub.K is mixed with water and a protective colloid. The polymerization initiator is added either now or only after dispersing of the monomer or after heating of the dispersion. A dispersion of very small monomer droplets in water is prepared from the heterogeneous mixture by thorough stirring at high speed, intensive mixers of any design being suitable for this purp
REFERENCES:
patent: 4012462 (1977-03-01), Chaudhary
patent: 4668737 (1987-05-01), Eichenauer et al.
patent: 5344877 (1994-09-01), Fischer et al.
patent: 5438099 (1995-08-01), Fischer et al.
Fischer Wolfgang
Guntherberg Norbert
Jahns Ekkehard
McKee Graham Edmund
Rosenau Bernhard
BASF - Aktiengesellschaft
Warzel Mark L.
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