Method of forming antislip surfaces on thermoformed products
First Claim
1. A process for selectively forming an antislip surface on a product thermoformed from a sheet comprising a thermoplastic material, the process comprising:
- forming droplets of a polymer;
applying the droplets onto a selected surface area of the sheet to form on the sheet a stippled pattern of non-interconnected bumps of the polymer across the selected surface area leaving the sheet exposed between and completely around individual ones of the bumps;
controlling the density of the droplets so that the bumps cover less than 50% of the selected surface area;
at least partially hardening the bumps that have been formed on the sheet; and
after the step of at least partially hardening the bumps, thermoforming the sheet at a thermoforming temperature, durably bonding the bumps to the sheet, and further hardening the bumps into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area;
wherein the polymer is selected so that the asperities have a hardness greater than the hardness of the sheet.
1 Assignment
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Accused Products
Abstract
A process for selectively forming an antislip surface on a product thermoformed from a plastic sheet is applied to truck bed liners, for example. The surface of the plastic sheet of HDPE or other thermoplastic material is cleaned and masked, to prepare a good molecular bonding surface on selected surface areas. A sprayable or liquid polymer selected to achieve desired characteristics of hardness and toughness without brittleness, such as a thermosetting elastomeric polymer, is formed into droplets, which are sprayed or otherwise applied onto the selected surface area. The droplets form a stippled pattern of primarily separate bumps across the selected surface area to be treated, occupying substantially less than 50% of the exposed area. After partial hardening of the bumps, the plastic sheet is thermoformed at thermoforming temperatures to produce the thermoformed product. Thermoforming tightly bonds the bumps or droplets to the thermoplastic sheet material, hardens the droplets forming macroscopic asperities, increases or enhances the three dimensional surface relief, and explodes some droplets with entrapped air to increase surface roughness.
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Citations
55 Claims
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1. A process for selectively forming an antislip surface on a product thermoformed from a sheet comprising a thermoplastic material, the process comprising:
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forming droplets of a polymer; applying the droplets onto a selected surface area of the sheet to form on the sheet a stippled pattern of non-interconnected bumps of the polymer across the selected surface area leaving the sheet exposed between and completely around individual ones of the bumps; controlling the density of the droplets so that the bumps cover less than 50% of the selected surface area; at least partially hardening the bumps that have been formed on the sheet; and after the step of at least partially hardening the bumps, thermoforming the sheet at a thermoforming temperature, durably bonding the bumps to the sheet, and further hardening the bumps into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area; wherein the polymer is selected so that the asperities have a hardness greater than the hardness of the sheet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A process for selectively forming an antislip surface on a product thermoformed from a sheet of plastic material comprising:
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cleaning a surface of the sheet for removing contaminants and preparing a good bonding surface; masking the sheet so as to expose a selected surface area to be provided with an antislip surface; forming into droplets a sprayable polymer; spraying a mist of the droplets and depositing the droplets onto the exposed selected surface area of the masked sheet, to form on the sheet a stippled pattern of primarily separate droplets without forming a continuous interconnected layer of the droplets across the selected surface area and while leaving the sheet substantially exposed between the droplets; controlling the time duration of the spraying so that the droplets cover less than 50% of the selected surface area; at least partially hardening the droplets that have been deposited on the sheet to form the stippled pattern thereon; after the step of at least partially hardening the droplets, thermoforming the sheet at a thermoforming temperature, durably bonding the droplets to the sheet, and further hardening the droplets into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area; and selecting the polymer to have a hardness after thermoforming that is greater than the hardness of the sheet. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A process for selectively forming an antislip surface on a cargo carrying surface portion of a truck bed liner thermoformed from a sheet of high density polyethylene (HDPE) comprising:
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cleaning at least a selected surface area of the sheet that is to be provided with the antislip surface, for removing contaminants, exposing the HDPE, and preparing a good molecular bonding surface; masking the sheet while leaving the selected surface area exposed; forming into droplets a thermosetting elastomeric polymer; spraying and depositing a mist of the droplets onto the exposed surface area of the sheet, and forming on the sheet a stippled pattern of primarily separate droplets without forming a continuous interconnected layer of the droplets across the selected surface area and while leaving the sheet substantially exposed between droplets; controlling the time duration of the spraying so that said droplets occupy substantially less than 50% of the selected surface area; carrying out an initial curing step for at least partially hardening the droplets that have been deposited on the sheet to form the stippled pattern thereon; and, after the initial curing step, thermoforming the sheet in a thermoforming temperature range of 250°
F. to 550°
F., durably bonding the droplets to the sheet, and further hardening the droplets into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A process for selectively forming an antislip surface on a product thermoformed from a plastic sheet of thermoplastic material comprising:
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mixing a polyurea prepolymer and an isocyanate to form a thermosetting elastomeric polymer; forming droplets of the polymer; applying the droplets onto the plastic sheet over a selected surface area, and forming a stippled pattern of primarily separate droplets across the selected surface area leaving the plastic sheet substantially exposed between droplets; controlling the density of the droplets so that the droplets cover less than 50% of the selected surface area; at least partially hardening the droplets forming the stippled pattern; and thermoforming the plastic sheet at a thermoforming temperature, durably bonding the droplets to the plastic sheet, and further hardening the droplets into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area; wherein the polymer is selected to have a hardness after thermoforming greater than the hardness of the plastic sheet. - View Dependent Claims (40)
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41. A process for selectively forming an antislip surface on a product thermoformed from a plastic sheet of thermoplastic material comprising:
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forming droplets of a hybrid polyurea polyurethane polymer; applying the droplets onto the plastic sheet over a selected surface area, and forming a stippled pattern of primarily separate droplets across the selected surface area leaving the plastic sheet substantially exposed between droplets; controlling the density of the droplets so that the droplets cover less than 50% of the selected surface area; at least partially hardening the droplets forming the stippled pattern; and thermoforming the plastic sheet at a thermoforming temperature, durably bonding the droplets to the plastic sheet, and further hardening the droplets into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area; wherein the polymer is selected to have a hardness after thermoforming greater than the hardness of the plastic sheet.
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42. A process for selectively forming an antislip surface on a product thermoformed from a plastic sheet of thermoplastic material comprising:
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forming droplets of a liquid polymer; applying the droplets onto the plastic sheet over a selected surface area, and forming a stippled pattern of primarily separate droplets across the selected surface area leaving the plastic sheet substantially exposed between droplets; controlling the density of the droplets so that the droplets cover less than 50% of the selected surface area; at least partially hardening the droplets forming the stippled pattern; thermoforming the plastic sheet at a thermoforming temperature, durably bonding the droplets to the plastic sheet, and further hardening the droplets into tough macroscopic asperities causing a relatively higher coefficient of friction over the selected surface area; and entrapping air in at least some of the droplets and exploding the entrapped air out through the droplets during the thermoforming, thereby forming rough edges on the droplets to increase the coefficient of friction; wherein the polymer is selected to have a hardness after thermoforming greater than the hardness of the plastic sheet.
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43. A method for providing an antislip surface on at least a selected surface area of a thermoformed product, comprising the following steps in sequence:
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(a) providing a base sheet comprising a layer of a first polymer; (b) applying a plurality of individual non-interconnected islands comprising a second polymer onto at least a selected surface area of said base sheet, so that said islands cover less than 50% of said selected surface area; (c) at least partially hardening said second polymer of said islands; (d) heating said base sheet; and (e) thermoforming said base sheet at a thermoforming temperature to form said thermoformed product by applying an air pressure differential across said base sheet in a mold, so as to bring a back side of said base sheet opposite said selected surface area into contact with a mold surface of said mold; wherein after said step (e), said islands provide an increased coefficient of friction greater than a coefficient of friction of said base sheet, and said selected surface area with said islands thereon forms said antislip surface. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. A method for providing an antislip surface on at least a selected surface area of a thermoformed product, comprising the following steps in sequence:
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(a) providing a base sheet comprising a layer of a first polymer; (d) applying a plurality of individual non-interconnected islands comprising a second polymer onto at least a selected surface area of said base sheet, so that said islands cover less than 50% of said selected surface area; (c) at least partially hardening said second polymer of said islands; (d) heating said base sheet; and (e) thermoforming said base sheet at a thermoforming temperature by applying an air pressure differential across said base sheet in a mold, so as to bring a back side of said base sheet opposite said selected surface area into contact with a mold surface of said mold; further comprising entrapping gas in at least some of said islands, and bursting open said gas-entrapping islands by expanding said entrapped gas during at least one of said steps (d) and (e).
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Specification