Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-02-04
2000-08-29
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 69, 525222, 525227, 525309, C08L 5106, C08L 3302, C08F27902
Patent
active
061110132
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the manufacture of polymer products.
Many plastics products are manufactured by forming a feed stock of polymer material into a desired shape or configuration using well known processes such as for example, extrusion, spread sheet formation or hot roll calendering in the case of plastics sheet manufacture. Especially in the case of spread sheet formation, this requires the polymer material to be substantially fluid. At the same time though it is often necessary to limit the temperature of the polymer material in order to avoid degradation thereof or impairment of its physical properties.
In the case of polyvinyl chloride (PVC) and like polymers there is more or less widely used the so-called vinyl plastisol technology in which small particles of PVC powder are suspended in a liquid carrier in order to reduce the viscosity thereof to a sufficient level to allow the physical manipulation thereof whether by spread coating or hot roll calendering or a similar process, to proceed under practical conditions, and upon subsequent heating of the mixture the PVC polymer resin melts into an amorphous mass into which the liquid carrier is absorbed. This technology is however peculiar to vinyl polymers and cannot be extended to other polymers.
In practice though significant environmental problems can arise caused by the migration of liquid plasticizers out of the material. The final product may also suffer loss of performance due to the presence of residual liquid plasticiser and/or due to leaching thereof from the product over an extended period of time in use thereof.
In the case of polyolefins it has been previously proposed to include small amounts of oils and the like to fine tune their processability. It has also been proposed to manufacture polyolefin products containing more or less large amounts of oils in order to modify processability and produce particular product characteristics such as softness. The utility of such products is howevever subtantially restricted since they contain relatively large amounts of liquid. It has not previously been possible, though, significantly to extend the processability of polyolefins without substantially compromising the physical properties of the final product.
It is an object of the present invention to avoid or minimize one or more of the above disadvantages.
It has now been found that the processability of polyolefins in the manufacture of products from polyolefins and the versatility and range of products based on polyolefins can be substantially improved and extended by inclusion of a plasticiser or processing aid comprising a selectively polymerisable liquid monomer system which is substantially non-polymerisable under the product forming, e.g. extrusion, spread-coating or calendering, conditions used in the product (e.g. sheet material) manufacturing process whilst being substantially polymerisable subsequently so as to produce a product substantially free of liquid plasticiser. In this connection it will be understood that there is normally used an initiator substance in order to induce polymerisation of the monomer and which is included together with the monomer in the monomer system. Accordingly in such cases it is important that the initiator is one that is selectively activatable i.e. is substantially inactive under the polyolefin product forming conditions but may subsequently be activated under suitable plasticiser monomer polymerisation or curing conditions.
Thus in one aspect the present invention provides a process for the manufacture of a plastics product from a polyolefin resin comprising the steps of: providing a plasticiser monomer system which is substantially non-polymerisable under the product shape (e.g. sheet) forming, e.g. extrusion, spread-coating or calendering, conditions used in the product (e.g. sheet material) manufacturing process and which acts as a plasticiser or processing aid under said shape forming conditions, whilst being substantially polymerisable subsequently so as to produce a product substantia
REFERENCES:
patent: 4115479 (1978-09-01), Daidone
patent: 4496692 (1985-01-01), Riew et al.
Kopchik Richard Michael
Mein Robert Ashley
Simpson Brian Robert
Asinovsky Olga
Forbo International S.A.
Seidleck James J.
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