Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1983-07-30
1985-07-09
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524459, 524503, 524733, 524825, 526202, C08L 2904
Patent
active
045283150
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns an improved process for the preparation of aqueous polymer dispersions stabilized by a protective colloid, especially by polyvinyl alcohol (PVAL), by one-step radical polymerization of vinyl halides and/or vinyl alkanoates, if needed with other compounds with unsaturated ethylene bonds copolymerizable with the former in amounts of up to 50 percent by weight.
The preparation of aqueous dispersions of polymers of the type mentioned above by emulsion polymerization is known in principle. The dispersing agent needed for the stabilization of the dispersions, namely an emulsifying agent, if needed in combination with a protective colloid, is generally included in the batch for this purpose. (cf. EP-B-No. 590,DE-B-No. 11 80 133 and DE-A-No. 17 70 395).
To achieve special effects (e.g. coarser consistency or bimodal particle size distribution), it has been suggested that the polymerization be started without the emulsifying agent and to add the latter, or the starting materials for its formation, only during the course of the polymerization (cf. DE-B-No. 15 20 849 and DE-A-No. 28 37 992).
There existed the need to develop a process by which dispersions can be prepared which are suitable a.o. for use in the preparation of adhesives, for the coating of paper, textiles, fiber fleeces and similar products, as additive to mortar and concrete mixes and as film-forming components in paints, which are also characterized by low structural viscosity and low viscosity despite high solids contents.
The last-mentioned property is especially advantageous if the preparation of a redispersible powder is intended, since, in this case, even dispersions with a high solids content can be sprayed through jets without any problem. Usually, conventionally prepared dispersions, in which additional protective colloids are included to produce redispersible powders, have a higher structural viscosity because of this addition.
The problems mentioned above can be solved in a surprising manner by the present invention. Furthermore, this new process can also be used to produce dispersions of polymers containing ethylene, which still have a high initial grabbing rate despite contents of ethylene units in the polymer exceeding 10 wt%, even exceeding 15 wt% and also even exceeding 20 wt%, and are therefore still highly suitable as adhesives.
The subject of the invention is a process for the preparation of aqueous polymer dispersions stabilized by a protective colloid, preferably only by protective colloid during the preparation, with solids contents of 20 to 75, preferably 20 to 70, especially 30 to 60 wt%, calculated with respect to the total weight, by one-step polymerization of vinyl halides, preferably of vinyl/chloride and/or of vinyl alkanoates, preferably of vinyl acetate, if needed together with not more than 50 percent by weight, with respect to the monomers that are liquid under the reaction conditions, other compounds with unsaturated ethylene bonds copolymerizable with the former monomers at temperatures of 0.degree. to 120.degree. C., preferably 20.degree. to 100.degree. C., and pressures of up to 200 bar, with the aid of at least partially water-soluble initiator systems and, if needed, in the presence of conventional additives. The process is characterized by the fact that the addition of protective colloid, preferably at least one PVAL with a degree of hydrolysis of 70 to 99.8 mol% and a mean degree of polymerization P.sub..eta. of 200 to 3,000, as first dispersing agent, begins only after the conversion of 1 to 60 wt%, preferably 2 to 25 wt%, calculated with respect to the total weight, of the monomers liquid under the reaction conditions.
In a preferred embodiment, 1 to 40 wt%, especially 5 to 30 wt%, of the monomers liquid at under the reaction conditions are initially placed in the reaction vessel. The remaining amounts of these monomers, i.e. 60 to 99 wt%, or especially 70 to 95 wt%, are added during the course of the polymerization, preferably at the rate of their consumption. Here, it was often
REFERENCES:
patent: 3630976 (1971-12-01), Mathieu
patent: 3843616 (1974-10-01), Richardson et al.
patent: 3883489 (1975-05-01), Matschke et al.
patent: 3929753 (1975-12-01), Itoh et al.
patent: 4093794 (1978-06-01), Chippaux
patent: 4189415 (1980-02-01), Eck et al.
Eck Herbert
Hannebaum Manfred
Kemenater Christof
Muserlian Charles A.
Sarofim N.
Schofer Joseph L.
Wacker-Chemie GmbH
LandOfFree
Process for the preparation of polymer dispersions and their app does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the preparation of polymer dispersions and their app, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of polymer dispersions and their app will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-909665