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
1995-10-11
1998-11-10
Jagannathan, Vasu
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...
524275, 524277, 524279, 523207, C08L 3300, C08L 9100
Patent
active
058345450
DESCRIPTION:
BRIEF SUMMARY
This invention relates to products which comprise water soluble or water swellable polymeric particles.
It is standard practice to produce such particulate polymeric material as relatively coarse particles, for instance having a size above 100 .mu.m, by techniques such as reverse phase bead polymerisation followed by drying and recovery of the polymer beads, and by gel polymerisation followed by drying and comminution. These processes can result in the production of some finer particles, known as fines and typically having sizes down to, for instance, 30 or 50 .mu.m. It is known to treat either the entire product or the fines so as to reduce dusting problems, and it is known to treat the particulate product so as to facilitate dissolution of the powder when it is mixed with water.
For instance in U.S. Pat. No. 3,839,500 polyacrylamide powder is coated with 0.1 to 20%, usually 0.1 to 10%, polyalkylene glycol which is usually applied as a solution. The process is said to cause some agglomeration. It is also stated that granulated polyalkylene glycol can be blended in a rotating drum with the polymer particles while heated to a temperature which is sufficient to melt the polyalkylene glycol and the blended product may then be cooled while mixing before being discharged from the rotating drum.
In U.S. Pat. No. 4,389,506, the dustiness of polyvinyl alcohol powder is reduced, and agglomeration is said to occur, by blending with 0.5 to 4% polyethylene glycol at a temperature at which the polyethylene glycol is liquid other methods involving the use of polyethylene glycol for reducing dustiness or improving water dispersibility of materials or as agglomerating agents appear in for instance DE-A-2616639, U.S. Pat. No. 4,797,275, JP-A-57049643 and JP-A57162610. In U.S. Pat. No. 3,891,592 a process is described for making polymers by oil-in-water emulsion polymerisation of an aliphatic diene, and polyalkylene glycol is included in the emulsion to cause agglomeration.
In many instances, for instance when the polymeric particles are wholly soluble in water, the initial dry particle size may be relatively unimportant since the particles are normally fully dissolved into water before use, for instance as a viscosifier or flocculant. However there are some instances where the particle size significantly influences performance. For instance when the particles are water swellable, water insoluble particles particular performance effects are achieved when the particles are very small, for instance below 10 .mu.m. Because of the problems of dusting, it is not practicable to supply such polymer particles in the form of a powder having a substantial content of particles below 10 .mu.m in size.
It is known to make extremely fine polymer particles (below 10 .mu.m) in the form of a reverse phase dispersion of the particles in oil by reverse phase emulsion polymerisation. The particles in the initial dispersion contain water but if desired the dispersion can substantially be dehydrated, for instance by distillation of the water from the dispersion.
The resultant stable anhydrous or hydrous polymeric dispersions in oil can be used for various purposes. For instance if the particulate polymer has viscosifying properties then addition of the dispersion to an aqueous liquid will result in thickening of it.
The oil is necessary to deliver the particulate polymer but does not contribute to the performance of the polymer, and can introduce some undesirable effects. For instance print paste thickeners (the thickeners for textile printing pastes) can advantageously be made by reverse phase polymerisation. Conventionally the print paste is made by blending the reverse phase dispersion with water, pigment and various other additives that are selected to optimise the quality of the print. The oil of the initial dispersion necessarily remains in the print paste and may influence the properties of the paste.
Similarly, when other reverse phase dispersions are used, their use normally results in the introduction of the oil phase into the medium t
REFERENCES:
patent: 3305019 (1967-02-01), Katzer
patent: 3435618 (1969-04-01), Katzer
patent: 3839500 (1974-10-01), Dexter
patent: 3891592 (1975-06-01), Chauvel et al.
patent: 3975341 (1976-08-01), Trapasso
patent: 4017431 (1977-04-01), Aldrich
patent: 4389506 (1983-06-01), Hassall, Jr.
patent: 4396731 (1983-08-01), Dawans et al.
patent: 4797275 (1989-01-01), Brooks et al.
patent: 5066711 (1991-11-01), Colon et al.
patent: 5126390 (1992-06-01), Duff
patent: 5346986 (1994-09-01), Schneider et al.
Allen Adrian Swinburn
Batty Norman Stewart
Whitley Martin William
Allied Colloids Limited
Asinovsky Olga
Jagannathan Vasu
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