Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Patent
1992-03-24
1995-06-27
Wu, David W.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
524528, 524468, 524470, 524490, 525240, 526352, C08J 328
Patent
active
054280796
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a solution of ultra-high molecular weight polyethylene in an organic solvent.
From "Ullmanns Encyclopedia of Industrial Chemistry", Vol. A10, (1987), page 522, paragraph 2.1.4 it is known to process polymers which cannot be processed as a melt, for example by spinning or extruding, in the form of a solution of the polymer in a suitable solvent. In particular, this applies in the case of polymers having a high molecular weight. In the said reference it is also pointed out that the concentration of the polymer in the solution must not be too low, since this lowers the production and increases the costs of solvent recovery. It is known that the viscosity of solutions of ultra-high molecular weight polymers increases with the concentration for a constant molecular weight of the polymer and with the molecular weight for a constant concentration. A disadvantage of these solutions is that they already have such a high viscosity at a low concentration that the solutions frequently cannot be processed, or can be processed only with difficulty, using the conventional equipment. In particular in the case of the processing of ultra-high molecular weight polyethylene, a very well known and widely used example of an ultra-high molecular weight polymer which hereinafter is indicated by UHMWPE, the concentration which is still permissible with regard to this restriction is frequently in conflict with economic operation because of the large amount of solvent to be removed and further processed, and the relatively low yield of processed UHMWPE.
The aim of the invention is to provide a solution of UHMWPE which does not have this disadvantage or has this disadvantage to a considerably lesser extent.
This aim is achieved according to the invention in that the polyethylene concentration is at least 15% by weight and the solution contains a crosslinked ultra-high molecular weight polyethylene.
When mention is made in this description of a solution, this is also understood to be, in addition to a composition consisting of non-crosslinked polyethylene, which is molecularly distributed in a solvent for polyethylene, a homogeneous composition of this type in which only crosslinked polyethylene is present or in which crosslinked polyethylene and uncrosslinked polyethylene occur alongside one another.
The solution according to the invention is found to possess an appreciably more favourable relationship between the total polyethylene concentration and the viscosity than the known solution. Consequently, more concentrated solutions than were possible hitherto can be processed using conventional equipment or, stating the advantage of the solution according to the invention in another way, the processing of solutions having a specific UHMWPE concentration places lesser demands on the processing equipment. In practice, what is achieved by this means is that, as a result of the higher permissible concentration, for a given flow rate in the processing equipment, for example an extruder, per unit time a greater amount of the polymer is converted into the desired product and a smaller amount of solvent has to be processed. This makes a considerably more economic process possible.
A further advantage of the solution according to the invention is that, for a chosen concentration, the service life of the equipment used for processing can be appreciably prolonged as a result of the now lower operating pressure, which is built up during spinning or extruding of the solution.
It is known from U.S. Pat. No. 2,908,659 to add specially prepared crosslinked particles called "d-microgels" to a solution of a polymer in order to introduce certain properties into products produced with the aid of said solution. Of such properties only dyeability is explicitly mentioned. The low-concentration solutions of UHMWPE or other high molecular weight polymers are not mentioned in the patent. The size of the crosslinked particles is emphatically restricted to at most 3 .mu.m and the amount of crosslinked particles to be added is emphatically
REFERENCES:
patent: 2908659 (1959-10-01), Shashoua
patent: 3956253 (1976-05-01), Braun
patent: 4598128 (1986-07-01), Randall et al.
patent: 4962167 (1990-10-01), Shiraishi et al.
patent: 5066755 (1991-11-01), Lemstra
Fred W. Billmeyer, Jr. Textbook of Polymer Science, 1984, p. 151 3rd edition.
Bastiaansen Cornelis W. M.
Simmelink Joseph A. P. M.
DSM N.V.
Wu David W.
LandOfFree
Solution of ultra-high molecular weight polyethylene does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solution of ultra-high molecular weight polyethylene, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solution of ultra-high molecular weight polyethylene will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-288058