Process for thermoforming reinforced polymer sheets
First Claim
1. An article thermoformed from a poly(ethylene terephthalate) sheet reinforced with glass fibers, which fibers are present in an amount within the range of about 5-50% by weight of the sheet composition, said thermoformed article having been thermoformed at a draw ratio of less than about 1.8, defined as the ratio of the initial thickness of the poly(ethylene terephthalate) sheet to the minimum wall thickness of the article, said article having without any further treatment at least one surface having an average roughness, RA, of about 0.1-0.8 μ
- m, and a concave optical imperfection index of less than about 6% of the surface area as determined by image analysis using a microscope having a magnification of 70 times.
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Accused Products
Abstract
Reinforced poly(ethylene terephthalate) sheets are thermoformed to articles having one or more surfaces in contact with the mold of such a degree of smoothness that they virtually completely replicate the mold face. When the mold face is completely smooth, the concave imperfections caused by air entrapment in the plastic material account for less than 6% of the surface area. Composite articles consisting of a face member and a backing member are made by thermoforming in a single mold a face member having one or more surfaces in contact with the mold face of such a degree of smoothness that it completely replicates the mold face, and its proportion of concave imperfections is less than about 6% of the surface area. The backing member is bonded in the mold with an adhesive to the face member, and the composite structure is allowed to remain in the mold for a sufficient time to permit subsequent removal without distortion. The initial polymer sheets are less than about 5% crystalline, but the thermoformed article is left in the mold until it crystallizes to the desired degree.
28 Citations
38 Claims
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1. An article thermoformed from a poly(ethylene terephthalate) sheet reinforced with glass fibers, which fibers are present in an amount within the range of about 5-50% by weight of the sheet composition, said thermoformed article having been thermoformed at a draw ratio of less than about 1.8, defined as the ratio of the initial thickness of the poly(ethylene terephthalate) sheet to the minimum wall thickness of the article, said article having without any further treatment at least one surface having an average roughness, RA, of about 0.1-0.8 μ
- m, and a concave optical imperfection index of less than about 6% of the surface area as determined by image analysis using a microscope having a magnification of 70 times.
- View Dependent Claims (2, 3, 4, 5, 6, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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7. An article having a face member and a backing member adhesively bonded to the face member, each member being thermoformed from a sheet of a poly(ethylene terephthalate) composition reinforced with a mineral filler, the face member having been thermoformed at a draw ratio of less than about 1.8, defined as the ratio of the initial thickness of the poly(ethylene terephthalate) sheet to the minimum wall thickness of the face member, said face member having without any further treatment at least one surface having an average roughness, RA, of about 0.1-0.8 μ
- m, and a concave optical imperfection index of less than about 6% of the surface area, as determined by image analysis using a microscope having a magnification of 70 times;
with the proviso the mineral filler in the face member is glass fibers, and the amount of the glass fibers is about 5-50% by weight of the sheet composition. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
- m, and a concave optical imperfection index of less than about 6% of the surface area, as determined by image analysis using a microscope having a magnification of 70 times;
Specification