Copolymers containing carboxyl groups and, if appropriate, terti

Details Copolymers containing carboxyl groups and, if appropriate, terti Copolymers containing carboxyl groups and, if appropriate, terti

1991-12-05

1994-01-04

Lipman, Bernard

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

5253282, 5253297, 5253299, 5253305, 525386, 5253303, 52631842, 526 86, 526 87, C08F22040

Patent

active

052761045

DESCRIPTION:

BRIEF SUMMARY
The invention relates to copolymers containing carboxyl groups and, if appropriate, tertiary amino groups, and soluble in organic solvents, a process for their preparation and their use in coating materials.
Copolymers containing carboxyl groups and, if appropriate, tertiary amino groups and their use in coating materials are known (cf, for example, EP-A 103,199, EP-B 51,275, EP-A 123,793, German Offenlegungsschrift 2,635,177, Japanese preliminary published specification 76,338/77 and WO 87/02041).
It is also known that problems arise in the preparation of acrylate copolymers if monomers having a reactivity differing greatly in comparison with acrylate monomers, such as, for example, vinyl esters of aliphatic monocarboxylic acids which have 5 to 15 C atoms and are branched in the .alpha.-position, are employed In these cases it is difficult to obtain unitary copolymers, i.e. copolymers having a homogeneous statistical distribution.
One possible means of solving this problem is the process described in U.S. Pat. No. 4,039,734 for the copolymerization of monomers of differing reactivity, in which at least a fraction of the reactive monomer is added continuously to the reaction mixture in an amount such that the relative ratio of monomers remains constant. The amount of monomer required for this in each case is determined by means of the heat of reaction liberated.
In the process described in German patent specification 2,032,647 unitary vinyl ester, vinyl-aromatic and hydroxyacrylate copolymers are obtained correspondingly by stepwise addition of the individual monomers In this process the total amount of vinyl ester is initially taken together with 5 to 15 % by weight of the total amount of the vinyl-aromatic and of the total amount of the other hydroxy-functional monomers and unsaturated carboxylic acids. The remaining amount of monomer is then either added gradually as a whole or is metered in at such a rate that the inflow of the OH-monomers and COOH-monomers takes a longer time than the inflow of the vinyl-aromatic. Disadvantages in this process are the very high residual monomer content (i.e. the amount of unreacted starting monomer, expressed in by weight, relative to the total amount of this monomer employed initially) of up to 40 % by weight of vinyl ester if a high proportion of vinyl-aromatic of up to 50 % by weight is used, and the toxicity problems associated therewith. Another unfavorable factor in respect of pollution of the environment with solvent when the paint films are dried is the high solvent content of the coating agents, caused by the high viscosity of the binder solutions. In addition there is a risk of cloudiness phenomena in the case of polymer solutions of a fairly high solids content; these phenomena can only be removed by adding further solvent.
The Shell technical information leaflet in the English language "VeoVa polymers LR-40 and LR-2041 for water-thinnable paints" also describes copolymers of this type containing vinyl esters, vinyl-aromatics and hydroxyalkyl esters, but these also exhibit the disadvantages just mentioned above.
Finally, some mass polymerization processes for the preparation of copolymers containing vinyl esters are also known in which, similarly, the total amount of the vinyl ester, if appropriate together with part of the total amount of the other monomers, and, if appropriate, initiator, is heated and then the remaining amount of monomers and initiator is added gradually (cf, for example, German patent specification 2,422,043 and German Offenlegungsschrift 2,615,101). Although it is possible in these processes to incorporate the vinyl ester completely (residual monomer content <10 % by weight), the copolymer solutions thus obtained are cloudy after the polymer material has incipiently dissolved and are not suitable for paint formulations.
Furthermore, copolymers containing hydroxyl groups are known from patent application DE 3,823,005, not yet published, which can be prepared by solution polymerization of vinyl esters, vinyl-aromatics, hydroxyalkyl es

REFERENCES:
patent: 3669942 (1972-06-01), Van Westrenen et al.
patent: 3956245 (1976-05-01), Van Steenis et al.
patent: 4062908 (1977-12-01), Van Acker et al.
patent: 4195004 (1980-03-01), van Acker et al.

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