Laminate structural plastic material
First Claim
1. A laminate structural material comprising:
- central inner core layer formed of a polyolefin material essentially devoid of reinforcing filler materials; and
a pair of outer skin layers sandwiching said core layer therebetween and each formed of a polyolefin material having a percentage by weight of a reinforcing filler material higher than the percentage by weight of filler material in said inner core layer, wherein said core layer has a thickness at least twice as great as the thickness of each skin layer.
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Abstract
An improved laminated structural material; an improved method of forming a relatively rigid structural article such as a pallet; and an improved structural article using the invention laminated structural material. The invention article is formed by separately extruding relatively thin outer skin layers of a 25% talc filled polyethylene material and a relatively thick central core layer of an essentially virgin polyethylene material; bonding the layers together to form a composite laminate strip including the relatively thin talc filled outer skins and the thick central core layer of virgin polyethylene; severing the strip to form upper and lower sheets; heating the upper and lower sheets in an oven to place them in a flowable condition; delivering the upper and lower sheets respectively to upper and lower molds carried by upper and lower platens of a press; vacuum forming the upper and lower sheets respectively to the upper and lower molds; and thereafter bringing the platens of the press together to selectively knit or fuse the upper and lower sheets together to form the article. The article produced by the invention methodology costs only slightly more than an article formed of virgin polyethylene material and yet has vastly superior stiffness characteristics as compared to the virgin polyethylene article while retaining substantially all of the superior impact characteristics of the virgin polyethylene article.
73 Citations
51 Claims
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1. A laminate structural material comprising:
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central inner core layer formed of a polyolefin material essentially devoid of reinforcing filler materials; and a pair of outer skin layers sandwiching said core layer therebetween and each formed of a polyolefin material having a percentage by weight of a reinforcing filler material higher than the percentage by weight of filler material in said inner core layer, wherein said core layer has a thickness at least twice as great as the thickness of each skin layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of forming a laminate structural material comprising the steps of forming a central inner core layer formed of a polyolefin material essentially devoid of reinforcing filler material and a pair of outer skin layers each formed of a polyolefin material having a percentage by weight of a reinforcing filler material higher than the percentage by weight of reinforcing filler material in said inner core layer, wherein said core layer has a thickness at least twice as great as the thickness of each skin layer;
bonding said layers together with said core layer sandwiched between said skin layers to form said laminate structural material. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of forming a relatively rigid structural article comprising the steps of:
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forming a central core layer of a first high impact plastic material; forming a pair of outer skin layers of a second plastic material having less impact strength than said first material but greater stiffness strength than said first material; bonding said layers together with said core layer sandwiched between said outer skin layers to form a laminate structural material; and thermoforming said laminate structure material to form said rigid structural article. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method of forming a pallet comprising the steps of:
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forming a central core layer of a high impact plastic material; forming a pair of outer layers of a second plastic material having less impact strength than said first material but greater stiffness strength than said first material; bonding said layers together with said core layer sandwiched between said outer layers to form a laminate structural material; and thermoforming said laminated structural material to form said pallet. - View Dependent Claims (37)
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- 38. A plastic structural article characterized in that the article is formed of a laminate structural material comprising a central core layer formed of a first high impact plastic material and a pair of outer skin layers sandwiching said core layer, wherein said core layer has a thickness at least twice as great as the thickness of each skin layer therebetween and formed of a second plastic material having less impact strength than said first material but greater stiffness strength than said first material.
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51. A twin sheet plastic structural article comprising first and second plastic sheets individually thermoformed and selectively fused together to form the twin sheet article, characterized in that said sheets are each formed of a laminate structural material comprising a central inner core layer formed of a polyolefin material essentially devoid of reinforcing filler material and a pair of outer skin layers sandwiching said core layer, wherein said core layer has a thickness at least twice as great as the thickness of each skin layer therebetween and each formed of a polyolefin material having a percentage by weight of a reinforcing filler material higher than the percentage by weight of reinforcing filler material in said inner core layer.
Specification