PVA-containing compositions
View Patent ↗An extrudable PVA-containing composition is disclosed, which enables PVA articles to be manufactured on conventional extrusion apparatus. The compositions includes a lubricant, such as a fatty acid amide, most preferably octodecanamide and is most preferably formed into pellets by cold pressing.,The compositions are suitable for manufacturing a variety of products.
1. A filled PVA-containing composition comprising, by weight:
40 to 70% PVA;
8 to 15% plasticizer;
0.5 to 1.5% internal lubricant;
0.0001 to 0.1% external lubricant; and
a filler.
2. A composition according to claim 1 comprising, by weight, 20-50% filler.
3. A composition according to claim 1 wherein the internal lubricant comprises a fatty acid amide.
4. A composition according to claim 3 wherein the fatty acid amide is a straight or branched C 12 -C 24 fatty acid amide.
5. A composition according to claim 1 wherein the plasticizer is selected from the group consisting of ethylene glycol, glycerol, triethylene glycol, a polyethylene glycols and C 2 -C 8 amides.
6. A composition according to claim 1 in the form of a tablet or pellet obtainable by cold-pressing.
7. A composition according to claim 1 wherein the filler comprises inert, inorganic material.
8. A composition according to claim 1 wherein the filler comprises a super absorbent material.
9. A composition according to claim 7 wherein the inorganic filler comprises calcium carbonate.
10. A composition according to claim 1 wherein the external lubricant comprises a stearate.
11. A composition according to claim 1 comprising, by weight:
50-60% PVA;
30-40% stearate-coated calcium carbonate;
8 to 15% glycerol;
0.5 to 1.5% octodecanamide; and
0.0001% to 0.1% zinc stearate.
12. A composition according to claim 1 prepared without liquefying the bulk of the PVA.
13. A composition according to claim 1 having a moisture content less than about 10% by weight but greater than 0.01% to bind the pellets or tablets.
14. A composition according to claim 1 wherein the filler comprises a solid particulate filler.
15. A PVA-containing composition, comprising a blend of:
PVA;
a fatty acid amide lubricant, wherein the fatty acid amide is a straight or branched C 12 -C 24 fatty acid amide;
from 0% to 20% by weight of a plasticizer selected from the group consisting of ethylene glycol, glycerol, triethylene glycol, polyethylene glycols and C 2 -C 8 amides;
stearate as an additional lubricant component;
at least 10% filler.
16. A composition according to claim 15 wherein the fatty acid amide comprises octodecanamide.
17. A composition according to claim 15 comprising up to 5% fatty acid amide lubricant, by weight.
18. A composition according to claim 15 wherein the filler comprises inert, inorganic material.
19. A composition according to claim 18 wherein the inorganic filler comprises calcium carbonate.
20. A composition according to claim 15 having a moisture content less than about 10% by weight.
21. A composition according to claim 15 having a moisture content greater than 0.01% by weight.
22. A composition according to claim 15 wherein the PVA has a molecular weight of at least about 10,000.
23. A composition according to claim 15 wherein the PVA is partially hydrolysed.
24. A composition according to claim 15 in the form of a tablet or pellet obtainable by cold-pressing.
25. A composition according to claim 15 wherein the filler comprises a solid particulate filler.
26. A PVA-containing composition, comprising a blend of:
PVA;
a fatty acid amide lubricant, wherein the fatty acid amide is a straight or branched C 12 -C 24 fatty acid amide;
up to 20% by weight of a plasticizer selected from the group consisting of ethylene glycol, glycerol, triethylene glycol, polyethylene glycols and C 2 -C 8 amides;
stearate as an additional lubricant component;
at least 10% filler, wherein the filler comprises calcium carbonate.
27. A method of making a composition according to claim 1 comprising:
blending the PVA with the plasticizer, the external lubricant, the internal lubricant and the filler, said internal lubricant including a fatty acid amide and said filler comprising a superabsorbent material, in the presence of an amount of moisture sufficient to bind the polymer feedstock into tablets or pellets upon cold compressing; and
cold pressing the feedstock into tablets or pellets.
28. A method according to claim 27 wherein the PVA, the internal lubricant and the filler are blended in a high speed blender.
29. A method according to claim 28 wherein the PVA, the internal lubricant and the filler are fed into the high speed blender gravimetrically.
30. A method according to claim 27 further comprising adding moisture to the components to be blended.
31. A method of making a PVA-containing composition comprising blending PVA with:
a fatty acid amide lubricant, wherein the fatty acid amide is a straight or branched C 12 -C 24 fatty acid amide;
up to 20% by weight of a plasticizer selected from the group consisting of ethylene glycol, glycerol, triethylene glycol, polyethylene glycols and C 2 -C 8 amides; and
stearate as an additional lubricant component;
at least 20% filler; and
pressing the composition into tablets or pellets.