METHOD OF MANUFACTURING A FOAM MAT

Abstract

A method of manufacturing a substantially flat foam floor mat is described. The raw materials for each color layer are separately mixed and heated below their foaming temperature in different batches, and separately pressed through heated rollers to form a plurality of unfoamed sheets. The temperature of the rollers are maintained within a range of 5° C. or less. Two or more unfoamed sheets from each batch are stacked together in a press and heated above their foaming temperature to permit the stacked sheets to foam, expand, and heat-weld together. The press restricts the sheets from vertical expansion while allowing horizontal expansion. Once the sheets are foamed, a series of alternating teeth and receiving slots are cut around the boundary of the mat to form an interlocking peripheral wall.

Claims

1. A method of forming a substantially flat foam floor mat, comprising: forming a stack of (i) at least first and second sheets of a first color, and (ii) at least third and fourth sheets of a second color; heating and pressing the stack such that the first sheet foams and heat welds to the second sheet, the second sheet foams and heat welds to the third sheet, and the third sheet foams and heat welds to the fourth sheet; and trimming the heated and pressed stack to form a boundary of interlocking teeth.

2. The method of claim 1, wherein the stack has no more than six sheets total.

3. The method of claim 1, wherein the stack comprises (i) three sheets of the first color, inclusive of the first and second sheets, and (ii) three sheets of the second color, inclusive of the third and fourth sheets.

4. The method of claim 1, wherein the step of forming a stack of (i) at least first and second sheets of a first color, and (ii) at least third and fourth sheets of a second color comprises: compounding together a blend of raw ingredients; heating the blend of raw ingredients together to a first temperature that is below a polymer foaming temperature; pressing the blend of raw ingredients through a pair of rollers and into sheets.

5. The method of claim 4, wherein the step of heating and pressing the stack comprises heating the stack above the polymer foaming temperature.

6. The method of claim 4, further comprising the step of maintaining the temperature of each roller within a range of five degrees Celsius when pressing the blend of raw ingredients into sheets.

7. The method of claim 4, wherein the sheets have a uniform thickness.

8. The method of claim 1, wherein the step of heating and pressing the stack comprises placing the stack between a tray and a top plate to restrict vertical expansion of the stack while horizontal expansion is unrestricted.

9. The method of claim 8, wherein the bottom tray has a first die that imparts a first texture to a bottom surface of the mat and the top plate has a second die that imparts a second texture to a top surface of the mat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a top plan view of the floor mat of the present invention;

[0012] FIG. 2 shows an embossed design on the top surface of the floor mat of FIG. 1;

[0013] FIG. 2a shows an alternative embodiment of an embossed design on the top surface of the floor mat of FIG. 1;

[0014] FIG. 2b is another embodiment of a design embossed in the top surface of the floor mat of FIG. 1;

[0015] FIG. 3 is a bottom plan view of the floor mat of FIG. 1;

[0016] FIG. 4 shows another design embossed in the surface of the floor mat of FIG. 3;

[0017] FIG. 5 shows a side view of the floor mat of FIG. 1; and

[0018] FIG. 6 is an enlargement of the side view of FIG. 5 in the encircled area labeled FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Referring to FIGS. 1 and 3, the floor mat 10 is a large, planar, flat, body 12 which has a first surface 16A and a second opposing parallel surface 16B. The two surfaces 16A and 16B are parallel to one another. The periphery of the floor mat is bounded by an interlocking perimeter 26, which comprises a series of teeth 28A and receiving slots 30A in alternating positions. Interlocking perimeter 26 also comprises four corners each having a smaller tooth 28B and a smaller receiving slot 30B. The surface 16A has a texture or three dimensional design 18′ and the second surface 16B has a texture or three dimensional design 18″, the two textures or designs can be the same or different. For purposes of this invention, texture means a three dimensional texture or design embossed in or embossed out of the mat surface. One or both surfaces 16A and 16B can also be smooth. The body is made up of two layers 14A and 14B (see FIG. 6). The two layers are bound together either by heat welding and/or an adhesive. Preferably, the two layers have the same chemical composition so that the two layers have the same coefficient of thermal expansion and the same elastomeric properties so that the two layers work together and respond similarly when subject to temperature changes and forces. The two layers have an outer surface 16A and 16B, respectively, and two inner surfaces 17A and 17B which preferably form an undulating boundary 20 between the two layers. Preferably, the inner surfaces 17A and 17B are not parallel to the first and second surfaces. Rather, the two inner surfaces 17A and 17B in the preferred embodiment meet to form undulating boundary 20 which has a topography of rolling hills and vales. The two outer surfaces 16A and 16B are parallel, or generally parallel. In the preferred embodiment, the inner surfaces 17A and 17B are generally not parallel to either of the outer surfaces. Thus, the thickness 22 of the body is generally constant across the entire length and width of the body. In contrast, in the preferred embodiment, the thicknesses of the first layer and second layer vary as the boundary undulates. Thus, the thickness of the first and second layers vary from point to point. The thickness 24A of the first layer 14A at a given point, together with the thickness 24B of the second layer at the same point are equivalent to the thickness 22 of the body. Thus, thickness 24C of the first layer 14A, at a second point, is less than the thickness 24A at the first point and the thickness 24D of the second layer 14B at the second point is greater than the thickness 24B of the second layer at the first point. The undulating boundary between the first layer and the second layer resists delamination of the two layers making the mats more robust as explained supra. However, the two layers 14A and 14B can be flat planar layers of the same or different thickness, each having a generally uniform thickness.

[0020] As described above, the texture of the first surface 16A can be different than the texture of the second surface 16B (see FIGS. 2, 2a, 2b, and 4 showing textures 18A, 18B, 18C and 18D, respectively). Similarly, the color of the first layer and the first surface 16A can be different than the color of the second layer 14B. Thus, the present mats give the purchaser the opportunity to have a selection of colors and/or a selection of textures. In addition, it permits the purchaser to form a checkerboard pattern or other pattern, assuming enough tiles are utilized, utilizing the different textures and/or colors of the mat tiles.

[0021] Preferably, the mats are made from resilient polymeric materials, such as natural or synthetic rubber, and most preferably from foam elastomeric material, such as polyethylene foam, polyurethane foam, EVA-PE foam (ethylene vinyl acetate-polyethylene foam elastomer), and EVA foam (ethylene vinyl acetate foam).

[0022] Preferably, the elastomeric mats are made from a combination of virgin polymer and recycle polymer, such as virgin EVA polymer and a mix of virgin and recycle PE (polyethylene) polymer. The blend of EVA and virgin and recycle PE are compounded together and heated to a temperature below the polymer foaming temperature and pressed into thin unfoamed sheets through rollers of uniform thickness within uniform temperatures of a range of 5° C.; preferably within a range of 1° C. The unfoamed sheets are 5 to 10 millimeters in thickness. Other thicknesses can be employed. The unfoamed sheets are sandwiched together, normally about six unfoamed sheets to each mat and placed in trays having a bottom surface with a die or mold for the texture and a top plate. The top plate may also have a die or mold for the texture for the other surface. The tray with the sandwich of unfoamed sheets of the raw composition and the top plate are pressed in a press and heated to a temperature to permit the elastomer to foam and expand. The press is required to keep the distance between the tray and the top plate constant to yield elastomeric foam mat of a predetermined thickness. Preferably, the three like unfoamed sheets have virtually identical compositions and blend together to form one foam layer of the mat. The mat's two foam layers may have slightly different compositions because their respective unfoamed sheets are made from different raw compositions (the differences can be slight) at different times (e.g., in different batches).

[0023] The virgin PE and the recycle PE have different rates of thermal expansion and different rates of foaming. The raw compositions of the unfoamed sheets are restricted in vertical movement and unrestricted in horizontal movement between the tray and the top plate in the press when heated. In the preferred embodiment, three unfoamed sheets of the raw composition will have one color and the other three unfoamed sheets of composition will have another color. Thus, one side of the mat may be red and the other side may be black, etc. The die in the bottom of the tray places one texture on one surface of the mat, and if the top plate has a die, it places a texture on the other surface of the mat. Preferably, the two textures are different although they can be the same. After the foaming reaction is completed by the heating in the press, the tray and the top plate are removed from the press and the unfinished mat is removed from the tray. The mat is allowed to cool and then it is passed to a cutting machine wherein the mat with the interlocking periphery is cut out of the unfinished mat. The mat is now complete.

[0024] In those cases where the top plate does not have a die for the texture, the mat comes out of the press with a texture only on one surface and a smooth planar other surface. The mat can be sent to a roller mill having a cool roller and a heated roller with a die attached thereto. The heated roller with die only heats the surface not having a texture permitting the heated roller with die to texture the other surface of the mat. The textured surface is kept cool by the cool roller. The mat is passed between two rollers and the roller that touches the texture surface is cool, whereas the roller with the die to give texture to the other surface is hot. The cooling roller prevents destruction or damage to the textured surface created in the press.

[0025] The above invention is not restricted to the specific embodiments disclosed herein; modifications and other embodiments of the invention are within the scope of the invention.