Method of thermoforming polyolefin resin
AssigneeMilliken & Company
InventorsMichael J. Mannion, Nathan A. Mehl
Life of this patent
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Abstract
A process for thermoforming a polyolefin resin sheet is provided having an aromatic aldehyde-polyhydric alcohol condensation product incorporated in the sheet to limit deformation of the sheet during the heating step.
Claims17
A process for forming a shaped article, comprising thermoforming a polyolefin resin by the steps of:
- (a) incorporating into the resin (i) the condensation product of two moles of an aromatic aldehyde and one mole of a penta- or hexahydric alcohol in a concentration of 250 to 20,000 ppm;
- and (ii) a pigment in an amount sufficient to opacify the resin;
- (b) forming the resin into a sheet having a thickness of 0.5 to 2.5 mm;
- (c) heating the sheet of resin to a temperature above the softening temperature and below the melt temperature of the resin, whereby the sheet is suspended in a heating zone, while being supported by its side edges;
- (d) shaping the softened sheet against a mold to form the shaped article;
- and
- (e) cooling the shaped article.
A process for forming a shaped article, comprising thermoforming a polyolefin resin, wherein the thermoforming includes the steps of:
- (a) incorporating into the resin (i) the condensation product of two moles of an aromatic aldehyde and one mole of a penta- or hexahydric alcohol in a concentration of 250 to 20,000 ppm, and (ii) a pigment in an amount sufficient to opacify the resin;
- wherein the resin has a melt flow index of from 2.5 to 15;
- (b) forming the resin into a sheet having a thickness of greater than 0.25 mm;
- (c) heating the sheet of resin to a temperature above the softening temperature and below the melt temperature of the resin, whereby the sheet is suspended in a heating zone, while being supported by its side edges;
- (d) shaping the softened sheet against a mold to form an article;
- and
- (e) cooling the shaped article.
A process for forming a shaped article, comprising thermoforming a polyolefin resin selected from the group consisting of propylene homopolymer and ethylene/propylene copolymer, by the steps of:
- (a) incorporating into the resin (i) the condensation product of two moles of an aromatic aldehyde and one mole of a penta- or hexahydric alcohol in a concentration of 250 to 20,000 ppm;
- and (ii) a pigment in an amount sufficient to opacify the resin;
- (b) forming the resin into a sheet having a thickness greater than 0.25 mm;
- (c) heating the sheet of resin to a temperature above the softening temperature and below the melt temperature of the resin, whereby the sheet is suspended in a heating zone, while being supported by its side edges;
- (d) shaping the softened sheet against a mold to form the shaped article;
- (e) cooling the shaped article;
- and
- (f) filling the article with a fluid.
Dependencies are inferred from the claim text.