Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1998-09-04
2000-09-12
Yoon, Tae
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526312, 524555, 524609, 524817, 523342, C08F22802, C08L 4100, C08L 3900
Patent
active
061179604
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to water-soluble, cross-linkable copolymers, processes for their preparation and their use.
Water-soluble polymers with ionic groups, so-called polyelectrolytes, have been known for a long time. These substances are polymers in which ionic groups, such as, for example, carboxylate or sulphonate groups, are firmly bonded to the polymer backbone via a chemical bond. As a rule good water-solubility and quite specific rheological properties, in general a high viscosity in an aqueous medium, result from this.
These polyelectrolytes are prepared by free radical polymerization of water-soluble, ethylenically unsaturated compounds which contain ionic groups. Examples of these are: acrylic acid, N-methylolacrylamide, acrylamido-2-methylpropanesulphonic acid (AMPS) and styrenesulphonic acid. Very high molecular weight polymers, aqueous solutions of which have a high viscosity, result from this preparation.
EP-B 94898 (U.S. Pat. No. 4,736,005) describes the preparation of very high molecular weight (molecular weight >1,000,000) terpolymers of 30 to 95% of dimethylacrylamide (DMA), 0.1 to 10% of N-methylolacrylamide (NMA) and 4 to 50% of acrylamidomethylpropanesulphonate (AMPS) and their use as rheological additives in the production of crude oil.
DE-A 2618898 (U.S. Pat. No. 3,965,032) relates to colloidal dispersions which comprise a water-soluble or water-dispersable copolymer polyelectrolyte with nonionic hydrophobic units, for example methyl methacrylate, and ionic hydrophilic units, for example AMPS, the preparation of which is carried out in solution polymerization in a water-miscible solvent. In concrete terms, copolymers which comprise the hydrophobic component in an excess of 2:1 to 6:1 are described.
EP-A 629650 (U.S. Pat. No. 5,278,222) and EP-A 671435 describe water-soluble and water-insoluble polymers of hydrophobic monomer units and 15 to 80% by weight or 30 to 50% by weight of monomers containing sulphonate groups as spraying auxiliaries in the spray drying of aqueous polymer dispersions.
Water-soluble polymers with high contents of crosslinkable water-soluble monomer units, such as N-methylolacrylamide (NMA), would in principle be of interest in the form of aqueous solutions thereof as binders for coating compositions or adhesives. Another conceivable use would be that as dispersing agents in aqueous polymer dispersions. Water-soluble polymers with a high NMA content have the tendency to have high molecular weights, with a correspondingly high viscosity of the aqueous solution. Water-soluble acrylic compounds, such as acrylic acid or N-methylolacrylamide, which is customary as a crosslinking agent, in fact tend to have very high degrees of polymerization, which severely impedes widespread use because of the resulting high viscosities.
Another disadvantage of polyelectrolytes based on water-soluble monomers is that such polyelectrolytes are often incompatible with a polymer dispersion and the aqueous polyelectrolyte solution separates off from the polymer dispersion as a serum.
SUMMARY OF THE INVENTION
The invention was therefore based on the object of providing water-soluble and crosslinkable polyelectrolytes which have relatively low molecular weights, in spite of a predominant content of water-soluble comonomer, and which, when used as an additive to aqueous polymer dispersions, show a high affinity for the dispersed phase and surface-active properties.
Surprisingly, it has been found that significantly lower molecular weights can be achieved by copolymerization of N-methylolacrylamide with acrylic compounds containing sulphonic acid or sulphonate groups. It has furthermore been found, surprisingly, that significantly lower surface tensions and lower viscosities already result by copolymerization of only small amounts of hydrophobic comonomers.
The invention relates to water-soluble, cross-linkable copolymers having a molecular weight of .ltoreq.500,000, comprising sulphonate groups, N-alkoxymethyl groups and consisting of water-insoluble, ethy
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patent: 4076928 (1978-02-01), Gross
patent: 4617321 (1986-10-01), MacDonald
patent: 4736005 (1988-04-01), Castner
patent: 5278222 (1994-01-01), Stack
Ball Peter
Dobler Walter
Koegler Gerhard
Kohlhammer Klaus
Rockinger Monika
Wacker-Chemie GmbH
Yoon Tae
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