CN1171554C - pad structure - Google Patents

Abstract

A flexible liner is provided. The flexible liner is formed from a sheet or web of polymer which is soft and has non-slip properties. The flexible liner has an upwardly extending ridge on its top surface formed of a polymer having a higher shore a hardness than the web. The bottom surface of the pad can have ridges and valleys or can be flat.

Description

pad structure

related application

This application claims priority to provisional applications Serial No. 60/182634 filed February 15, 2000 and Serial No. 60/182276 filed February 14, 2000, the entire contents of which It is incorporated into this application by reference.

field of invention

The present invention generally relates to structures suitable for use as adhesive-free, non-slip underlayment to cover and/or protect generally horizontal planar surfaces, such as shelves, drawers, etc., and to methods of making such structures.

Background Art of the Invention

Consumers use a variety of boards as cushioning and padding materials in their homes. For example, decorative paper has been used for shelf and drawer liners for many years. Certain decorative papers have adhesive on one side to provide a more permanent backing. Plastics such as polyvinyl chloride are also commonly produced in sheet form or as reinforced composites, often with an adhesive coating on one side for consumer use as padding.

An alternative type of liner construction is described in US Patent No. 4,947,999. The structure comprises a plastic plate with a substantially flat bottom surface for placement on the surface of an underlying shelf or drawer. An overall raised pattern of ridges is raised upwardly from the top surface of the board. The tops of the ridges are generally coplanar and have a reduced surface area to support items such as glasses and cutlery, and to allow air to flow to the underside of the items.

While this type of pad construction offers certain advantages over pads previously known in the art, further improvements are desired. For example, ribbed shelf liner articles according to the construction described in the aforementioned US Patent No. 4,947,999 are currently marketed under the trademark "PLAST-O-MAT". The article is composed of relatively hard and smooth plastic and has a tendency to curl when placed on a flat surface. Therefore, it is difficult to keep the pad in place on a smooth support surface because it will have a tendency to slide along the support surface when it is subjected to a force parallel to the plane of the pad, e.g. The force produced by moving an item on the mat. This shortcoming has been recognized in US Patent No. 4947999, which describes the pad construction as a "semi-rigid" construction and suggests securing it in place with double sided tape.

Introduction to the invention

The present invention provides an underlayment structure suitable for covering or protecting a horizontal support structure such as a shelf, the underlayment structure comprising a flexible sheet having a top surface and a bottom surface. The flexible sheet is non-rigid and is composed of a first polymeric resin that is sufficiently soft so that the flexible sheet does not curl and the bottom surface is non-slip. On the top surface of the flexible board are a plurality of upwardly extending ridges comprising a second polymeric resin that is harder than the first polymeric resin and provides a low friction surface on the top edges of the upwardly extending ridges. In one embodiment of the invention, the bottom surface is not flat and includes downwardly extending ridges of flexible polymeric resin. The pad structure can be manufactured by multi-layer one-shot extrusion.

Brief description of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial top plan view of a liner of the present invention.

FIG. 2 is a partial bottom plan view of the liner of FIG. 1 .

Fig. 3 is a partial cross-sectional view of the liner of Fig. 1 taken in the direction of arrow 3-3.

Figure 4 is a cross-sectional view of the liner of Figure 1 taken in the direction of arrows 4-4.

Figure 5 is an end view of a second embodiment of the present invention.

Figure 6 is an end view of a third embodiment of the present invention.

Figure 7 is an end view of a fourth embodiment of the present invention.

Detailed Description of the Invention

The pad structure described in US Patent No. 4,947,999 (which is incorporated herein by reference in its entirety) can be modified by using at least two different polymeric resins in the manufacture of the structure. The underside of the pad structure, which surface mates with the bearing surface, is composed of a relatively soft polymeric resin. The resin is selected to provide non-slip characteristics to the underside of the pad structure. The term "anti-skid" means to inhibit or impede slipping or sliding, but not completely prevent.

Consequently, the bottom surface will be free of adhesive, ie not firmly fixed on the support surface. The area of the floor that is in contact with the support surface will effectively inhibit or impede sliding or sliding of the pad structure tangentially, laterally, or in a plane parallel to the support surface. Thus, no tape or other adhesive is required to hold the pad structure in place on a smooth horizontal support surface. With no adhesive, the pad structure can be easily picked up from the support surface for reuse or replacement without damaging the support surface or leaving adhesive residue that is often difficult to clear. The polymeric resin making up the plates or webs of the pad structure is preferably selected to be sufficiently flexible so that the pad structure conforms to the contour of the support surface when in contact with the support surface and remains Consistent (i.e. no visible curl). Therefore, the use of rigid or semi-rigid polymeric resins should be avoided in the manufacture of the plate or web portions of the gasket structure.

The polymeric resin can be any polymeric resin that is flexible enough to conform to the surface without being detrimental to the surface. Usable resins are polyurethane, polyolefin, polyvinyl chloride, polyester, polyamide, and the like. The resin may be plasticized to provide the desired hand, hardness, non-curl and slip resistance properties, or may be a copolymer to provide the desired properties.

In a preferred embodiment of the invention, the polymeric resin used for the plate or web portion comprises polyvinyl chloride containing an amount of plasticizer in order to render the web flexible and non-slip. Plasticized polyvinyl chloride resins are known, for example, as described in the Encyclopedia of Polymer Science and Engineerring, Second Edition, Supplement pp. 822-889 (1989) in the section entitled "Vinyl Chloride Polymers".

An example of a commercial resin suitable for use in the flexible web of the gasket construction of the present invention is APEX 3301-80NT resin (available from the Plastics Division of Teknor Apex Company of Pawtucket, Rhode Island). The resin has a Shore A hardness of 66/60 (15 second reading), a specific gravity of 1.16, a tensile strength of 1500 lbs/sq.in., and an ultimate elongation of 450%. Typically, flex boards have a Shore A hardness (15 second reading) of from about 50 to about 75. However, this hardness is always lower than that of the resin forming or covering the upwardly extending ridges. In an alternative embodiment, the flexible sheet may comprise foamed or unfoamed polymer containing isocyanate residues. The composition of the flexible polymer sheet is not critical as long as it is soft enough to conform to the surface, has sufficient strength at the desired thickness, provides slip resistance and is compatible with and bonds to the harder polymer material of the upwardly extending ridges surface. The flexible polymer sheet may be plasticized, or may be a copolymer formed with desired properties.

The flexible web in a preferred embodiment of the invention is substantially continuous, ie it does not contain any holes, perforations or other openings. This feature makes the pad structure attractive and pleasing in appearance, and makes the pad structure easy to clean with a sponge or the like. Thus, the pad structure is able to fully protect the support structure surface against dirt, dust, water, food crumbs and the like. Another advantage of the cushion construction of the present invention is the "shock absorbing" effect provided by the resilient and relatively soft polymeric resin. This reduces the tendency for fragile items such as glasses and fine china to crack, crack or shatter when placed forcibly on a hard support surface such as a wooden shelf.

In certain embodiments of the invention, the liner structure is substantially solid and substantially free of larger sized voids and other voids. However, in other embodiments, the flexible sheet is suitably foamed (eg, small cells). The bottom surface of the flexible sheet may be flat or substantially flat such that when the gasket structure is placed on a flat surface, such as a shelf, all or substantially all of the bottom surface is in direct contact with the flat surface. However, in a preferred embodiment of the invention, the bottom surface has means as ridges extending downwardly and defining an integral raised pattern on the bottom side of the flexible board. The bottom edges of the downwardly extending ridges are preferably coplanar so as to provide a horizontal support "surface" or means. The configuration of downwardly extending ridges may provide a reduced and substantially level surface area in contact with the planar surface. Thus, air can flow under the cushion structure, preventing moisture build-up and mold formation.

The downwardly extending ridges may combine into a plurality of straight, corrugated or zigzag parallel ridges. In one embodiment of the invention, the downwardly extending ridge is below and parallel to the upwardly extending ridge. Thus, the bottom surface of the pad structure may have a corrugated or "microwave" profile. In one embodiment of the invention, the downwardly extending ridge may be made of a polymeric resin having a lower Shore A hardness than the flexible web.

In one embodiment of the invention, the thickness of the flexible web is uniform, generally from about 0.1 mm to about 2 mm, preferably from about 0.2 mm to about 1 mm. However, in another embodiment, the thickness of the flexible sheet may vary, preferably in a regular fashion or pattern. For example, the thickness of the flex sheet may be relatively thinner (eg, about 0.1 mm to about 1 mm) in the middle of the upwardly extending ridges and relatively thicker (eg, about 0.6 mm to about 3.0 mm) at the upwardly extending ridges. Variations in the thickness of the flex sheet can also be used to create downwardly extending ridges.

The downwardly extending ridges may be formed from one of the aforementioned relatively soft polymeric resins bonded to the plate portion of the liner structure. In one embodiment of the invention, the same relatively soft polymeric resin is used for both the plate and the downwardly extending ridges, as this simplifies the manufacture of the pad structure. It is also generally desirable that the downwardly extending ridges be slightly rounded or otherwise flattened to ensure sufficient friction between the bottom edge of the ridges and the surface supporting the pad structure to make the pad structure non-slip. In one embodiment, the downwardly extending ridges may be covered with a softer plastic than the flexible plastic forming the web. This makes for a more slip-resistant pad.

In another aspect, the means extending upwardly from the flexible board and defining an integral raised pattern on the top surface of the flexible board comprises (at least on its top edge) a polymeric resin that is harder than the polymeric resin used to form the bottom surface of the flexible board. For example, the device may be in the form of ridges. By using a harder polymeric resin, items placed on the raised pattern can be easily removed from the liner structure even in a direction generally parallel to the plane of the liner structure due to the relatively low coefficient of friction. This feature is particularly advantageous when the ridge has a relatively thick top edge, thereby having a relatively large contact surface area with the bottom of an item placed on the cushion structure. However, the polymeric resin used to make the ridge must not be so rigid that the ridge hinders the pad structure's ability to conform to the contour of the supporting surface. It is therefore preferred that the harder polymeric resin is absent in the region between the upwardly extending ridges. When a relatively stiff polymeric resin is used to form the upwardly extending ridges, the cross-sectional area of the ridges can be reduced as necessary to maintain suitable flexibility in the overall pad structure.

In a preferred embodiment of the present invention, the polymeric resin used to form the upwardly extending ridges is compatible, easily mixed or bonded to the polymeric resin used to make the plate portion so that direct contact between the ridge and plate portion is possible. Forms a good bond. Accordingly, it is not necessary to use a separately applied layer of adhesive to connect the ridge to the plate portion. Furthermore, the resulting pad structure is very resistant to delamination (separation of the ridges from the flexible sheet). In one suitable embodiment, the upwardly extending ridge (or at least the top edge of the ridge) comprises polyvinyl chloride resin. The resin may be plasticized, typically at a lower level of plasticizer than in the flex sheet polymeric resin, and sufficiently low so that the exposed surface of the top edge of the upwardly extending ridge has a low coefficient of friction. The resin used to form or cover the upwardly extending ridges has a Shore A hardness (15 seconds) of about 60 to about 100, preferably about 65 to about 90. The Shore A hardness of the resin forming or covering the ridge is higher than the Shore A hardness of the web or plate portion.

Suitable polymeric resins for forming upwardly extending ridges include POLYFIEX 118514 (available from Flex Technologies, Inc.) and APEX 3189 (available from the Plastics Division of Teknor Apex Company). The characteristics of these PVC resins are as follows:

POLYFLEX 118514 APEX 3189

Shore A hardness (15 seconds reading) 85 78/65

Specific gravity 1.34 1.37

Tensile Strength (lbs./sq.in.) 3700 2950

Ultimate elongation (%) 330 320

In one embodiment of the invention, the raised pattern is defined by a plurality of substantially parallel ridges. The ridges may be straight or in a corrugated or zigzag pattern or the like. The top edge of the ridge can be pointed, rounded or flattened. In general, a flat top edge is not preferred as air circulation will be restricted and items placed on the cushion structure may be slightly more difficult to remove, especially if the ridge is relatively wide because The contact surface area of the surface is increased. The top edges of the ridges will be coplanar so as to pass through the horizontal support "surface". In a preferred embodiment of the invention, the ridge is rounded, has a base width in the range of about 1 mm to about 4 mm, and a height in the range of about 0.2 mm to about 3 mm (from the point where the ridge attaches to the bottom web or plate measured from the centerline of the plate or web). The upwardly extending ridge need not be made entirely of a relatively hard polymeric resin. For example, the base of each ridge may comprise a relatively soft polymeric resin, with only a relatively hard polymeric resin serving as a thinner cap on the top edge of the ridge. The spacing of the ridges can be adjusted as desired to effectively support items placed on the cushion structure. For example, the ridges may be dense enough to prevent tall and relatively narrow items such as glasses from tipping and tipping over. For example, a suitable pitch ranges from about 5 mm to about 15 mm, preferably from about 7 mm to about 11 mm.

The upwardly extending ridges not only give the backing structure a desired texture, for example, but also form channels into which water overflowing from glasses and dishes can easily drain and then evaporate. Thus, the pad structure of the present invention reduces the tendency to form water rings and the like compared to known flat top pads.

The gasket structure of the present invention can be manufactured by a multi-layer one-time extrusion method. In this method, a relatively harder polymeric resin used to form the plurality of upwardly extending ridges is extruded in multiple passes simultaneously with a relatively softer polymeric resin used to form the flexible sheet or web member. Extrusion fusion at elevated temperature and pressure into a common coextrusion die having the desired gasket member cross-section to effectively form a bond at the interface between the two polymeric resins. In this way, the relatively stiff polymeric resin is extruded through the die only at separation points corresponding to the predetermined positions of each upwardly extending ridge.

The decorative appearance of the pad structure can also be easily altered as desired, although the polymeric resins used to form the flex plates and spines can all be clear, tinted or pigmented to give the pad structure an overall appearance. For example, the web material and ridge material may be colored complementary or contrasting colours. The web material can be transparent or colored and the ridge material can be colored and opaque. Alternatively, the web material is clear or transparent and the spine material is colored.

Pad structures of the present invention can be made in any suitable length and width. For example, when the liner is designed for a common width household shelf, the liner width can be adjusted accordingly (eg, from about 250 mm to about 400 mm) by selecting an appropriately sized coextrusion die. Alternatively, a wider coextrusion die can be used and the coextruded liner structure cut to the appropriate width by slitting or the like. Coextrusion enables the manufacture of cushion structures of essentially unlimited length. However, for ease of packaging and shipping, the liner structure is typically cut to a shorter suitable length (eg, from about 0.9 meters to about 4 meters). An end user can easily cut the liner structure with scissors, scraper, etc. to assemble the liner structure. In an alternative embodiment, the width of the extrusion die can be equal to the desired length of the liner and the extruded sheet can be cut across the width to give the liner the proper width. The method provides a pad having ridges extending across the width of the pad.

In the drawings, the same reference numerals are used to designate the same parts of the pad.

Fig. 1 is a partial plan view of a liner 1 of the present invention. The liner 1 comprises a flexible non-slip plastic web 3 which may be formed from a plasticized polymer if desired. The liner 1 has ridges 2 of plastic having a higher Shore A hardness than the web. The valleys between the ridges are indicated by 4 .

FIG. 2 is a bottom partial plan view of the liner 1 of FIG. 1 showing the ridges 5 and valleys 6 . The ridge 5 is in contact with the surface on which the pad is arranged.

FIG. 3 is a view along arrow 3-3 in FIG. 1 . The web 3 of the pad 1 consists of a flexible plastic which can be arranged flat without curling and which can also come into non-slip contact with the surface on which it is arranged. The spine 2 is formed of a plastic having a higher Shore A hardness than the web 3 . The top and bottom surfaces of the web are corrugated with valleys and ridges. This ridge 2 is covered by a harder plastic than that of the web 3 .

Fig. 4 is a cross-sectional view along the direction of arrow 4-4 in Fig. 1 . FIG. 4 shows the liner 1 cut through the thinner part of the web 3 . The pad is supported by ridges 5 which allow air to flow between the bearing surface and the pad 1 . The top surface comprises valleys 4 and ridges 2 covered by caps.

Figure 5 is an end view of an embodiment of the invention wherein the liner 1 comprises a web 3 having a ridge 2 of triangular cross-section. The upper surface 4 of the web 3 is substantially flat and has ridges 2 extending upwards. The bottom surface of the web 3 has a corrugated cross section with ridges 5 and valleys 6 .

Figure 6 is an end view of a pad 1 comprising a substantially flat web 3 with a ridge 2 on the top surface made of a harder plastic than the web. The ridge 2 is co-extruded with the web 3 . However, the spine 2 could be formed separately and connected to the web 3 by fusing, gluing or the like. The web 3 is flexible so it lies flat on the surface. The spine 2 is made of a harder plastic than that forming the web 3 .

Figure 7 is an end view of a liner 1 in which the web 3 is corrugated with ridges 2 and valleys 4 on the top surface and ridges 5 and valleys 6 on the bottom surface. The pad rests on the ridges 5 of the bottom surface. The ridges 5 correspond to the valleys 4 of the top surface. The ridge 2 is covered by a harder plastic than that of the web 3 , the ridge covered by the cap comes into contact with and supports the item on the top surface of the web 3 . In an alternative embodiment, the ridge can be formed from a harder plastic, the ridge rising from the valley 4 and protruding above the top of the ridge 2 .

The non-curling and non-slip liner of the present invention can be easily installed and removed since no adhesive is required to hold the liner in place.

The plastic or resin from which the web 3 of the pad 1 is made can be any plastic or resin having the desired flexibility, hardness and non-slip properties. The plastic or resin can be plasticized or not, and can be foamed or not. Resins or plastics such as polyurethanes, polyesters, polyamides, polyolefins, and polyvinyl chlorides can be used to form the webs, either selected as plastic or resin-forming monomers, or with the addition of plasticizers known in the art. The plastic forming the web has a Shore A hardness (15 seconds) of from about 50 to about 75, preferably from about 55 to 70.

The ridges of the top surface of the gasket of the present invention are formed from or covered with a harder plastic or resin than the flexible plastic forming the web. The plastic or resin forming or covering the ridges has a Shore A hardness (15 seconds) of from about 60 to about 100, preferably from about 65 to about 90. Preferably, the ridges of the top surface of the pad comprise a plastic or resin that is 3 Shore A durometer units harder, more preferably 5 Shore A durometer units harder, than the plastic or resin forming the web of the pad, Most preferably hard 7 Shore A durometer units.

Claims (12)

1. gasket construction comprises: flexible board, and this flexible board has top surface and basal surface, and described flexible board is made by first polymer resin, and this first polymer resin is enough soft, so that this flexible board is not curled, and makes basal surface anti-skidding; And a plurality of upwardly extending ridge on the flexible board top surface, described upwardly extending ridge is made by second polymer resin, this second polymer resin is harder than first polymer resin, and makes the Shore A hardness on top edge surface of described upwardly extending ridge under the situation of 15 seconds readings from about 60 to about 100.

2. gasket construction according to claim 1, wherein: the basal surface of this flexible board is for flat substantially.

3. gasket construction according to claim 1, wherein: the basal surface of this flexible board is corrugated.

4. gasket construction according to claim 1, wherein: the basal surface of this flexible board comprises the ridge of a plurality of downward extensions, this ridge that extends is downwards made by described first polymer resin.

5. gasket construction according to claim 4, wherein: this ridge that extends downwards is flat or is formed with fillet.

6. gasket construction according to claim 4, wherein: this ridge that extends downwards is directly below described upwardly extending ridge, and is and parallel with described upwardly extending ridge.

7. gasket construction according to claim 1, wherein: this upwardly extending ridge is straight, and parallel to each other.

8. gasket construction according to claim 1, wherein: this first polymer resin comprises the polyvinyl chloride of plasticising.

9. gasket construction according to claim 1, wherein: this second polymer resin comprises polyvinyl chloride.

10. gasket construction according to claim 1, wherein: this first polymer resin and second polymer resin all comprise polyvinyl chloride, and the plasticising of first polymer resin is higher than second polymer resin.

11. gasket construction according to claim 1, wherein: this upwardly extending ridge has triangular cross-section.

12. gasket construction according to claim 1, wherein: this second polymer resin is than first polymer resin at least 3 Shore A hardness units firmly.

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