Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-12-18
1999-11-16
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
25240052, 25240061, 524399, C08J 510, C08K 515
Patent
active
059859644
DESCRIPTION:
BRIEF SUMMARY
The invention relates to stabilized polyvinyl chloride (PVC) containing recycled material, to stabilizer mixtures, to a process for the preparation of stabilized PVC containing recycled material, and to the use of stabilized PVC containing recycled material.
PVC, in particular flexible PVC for external applications, for example as roof membranes or agricultural sheeting, is in some cases exposed to weathering for some time. Roof membranes, for example, usually have a service life of more than 15 years. It is known that a significant loss of material properties can occur over the life of the materials. Typical problems which occur on recycling, reprocessing of the recycled material or mixtures of used and new PVC during sheeting production by, for example, calendering are adhesion to the hot metal surfaces and a drastic drop In thermal stability. This disasterously adverse effect of the used material on recycling is also found even In mixtures containing a relatively low proportion of used material.
The object of the present invention was therefore to provide stabilized PVC containing recycled material, where the stabilizers used are ecologically acceptable and at the same time enable processing without adhesion to the metal surfaces of the processing machine and without significant decomposition (discoloration) of the PVC. In particular, stabilizers containing lead or cadmium should be avoided.
It has now been found that PVC which contains recycled material and has been stabilized using a mixture of at least one lubricant and a stabilizer containing no lead or cadmium compounds has excellent thermal stability and good processing properties.
The invention therefore proposes stabilized PVC containing recycled material, which comprises (a) PVC containing at least 1% of recycled materials (b) at least one lubricant and (c) at least one stabilizer containing no lead or cadmium compound, (c) being a metal salt of a fatty acid and a terminal epoxide compound.
For the purposes of this invention, (a) PVC Is also taken to mean copolymers or graft polymers of PVC with polymerizable compounds, such as acrylonitrile, vinyl acetate or ABS, and also includes suspension, bulk and emulsion polymers. However, PVC for the purposes of this invention does not include postchlorinated PVC. Preference is given to PVC as a suspension, bulk or emulsion polymer, including in combination with polyacrylates.
The recycled material is recycled PVC, for example flexible PVC from external applications, such as agricultural sheeting or PVC roof membranes which has been exposed to extended weathering.
The recycled material can also contain small amounts of foreign materials, for example bitumen, paper, pigments and adhesives, which are frequently difficult to remove. These foreign materials can also originate from contact with diverse substances during use or processing, for example paint components, metal traces, initiator residues, dirt, fertilizers or traces of water. Small amounts of foreign polymers, for example polyethylene or EVA, can also be present as a consequence of collection of used material.
The recycled material content is, for example, 1-100%, for example 2-10%. The proportion of recycled material is preferably at least 2%, particularly preferably at least 5%, based on the total amount of stabilized PVC.
Preferred stabilized PVC containing recycled material is that as described above, wherein (b) is at least one lubricant selected from the group consisting of C.sub.8 -C.sub.40 fatty alcohols, C.sub.8 -C.sub.40 fatty acids, C.sub.8 -C.sub.40 fatty acid esters, C.sub.8 -C.sub.40 fatty amides, liquid or solid paraffins, high-density polyethylene waxes (M.about.3000-9000) and low-density polyethylene waxes (M.about.2000). Suitable lubricants are also described in "Plastics Additives", Edited by H. Gachter and H. Muller, Hanser Verlag, 3rd Edition, 1990, pages 466-470. The lubricant is preferably an externally acting lubricant, particular preference being given to polyethylene waxes or stearic acids. Very particular preference is
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Drewes Rolf
Herbst Heinz
Hoffmann Kurt
Pfaendner Rudolf
Rajguru U. K
Seidleck James J.
Witco Vinyl Additives GmbH
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