US 3771787 A
A substantially maintenance-free surface suitable as a playing field has a flat upper face consisting of a rugged synthetic fiber pre-treated with an elastomeric coating which provides the desired abrasion resistance and ball-skid-speed thereon. Unlike artificial grass, no filaments protrude upwardly from the surface.
Description (OCR text may contain errors)
[ 1 Nov. 13, 1973 1 1 PLAYING COURT SURFACE AND METHOD OF CONSTRUCTING SAME  Inventor: Sidney B. Wood, Jr., New York,
 Assignee: Tennis Services, Inc., New York City, NY.
22 Filed: June 29,1972
211 Appl. No.: 267,381
Related US. Application Data  Continuation of Ser. Nos. 794,641, Jan. 28, 1969, Pat. No. 3,577,894, and Ser. No. 113,915, Feb. 9, 1971, abandoned.
 US. Cl. 273/29 R, 161/160  Int. Cl A63b 61/00  Field of Search 94/7, 3 S; 273/29 R,
273/176 J; 272/565 SS; 161/160  References Cited UNITED STATES PATENTS 3,438,312 4/1969 Becker 273/29 R X 3,620,890 11/1971 Kemmler..... 161/160 3,676,199 7/1972 Hewitt 117/1385 X 3,684,630 8/1972 Sensenig 161/160 X 3,433,137 3/1969 Henderson... 94/7 3,407,714 10/1968 Henderson... 94/7 3,446,122 5/1969 Raichle 94/7 1,761,165 6/1930 Winch 94/7 1,679,374 8/1928 Reirden 94/7 X 3,661,687 5/1972 Spinney 161/21 2,515,847 7/1950 Winkler 94/7 X OTHER PUBLICATIONS References E-K have been transferred to this application from parent case 113915.
Primary Examiner-Nile C. Byers, Jr. Attorney-Henry W. Archer  ABSTRACT A substantially maintenance-free surface suitable as a playing field has a flat upper face consisting of a rugged synthetic fiber pre-treated with an elastomeric coating which provides the desired abrasion resistance and ball-skid-speed thereon. Unlike artificial grass, no filaments protrude upwardly from the surface.
Where the surface is to be used temporarily indoors or outdoors, an under-cushion is foamed to the underside thereof, which cushion consists of a sturdy, low density, plastic expanded foam having a high coefficient of friction and a permanent dry tackiness for holding the surface firmly and without bunching to various surfaces without any fastening means. The surface is light enough to roll up for compact storage and the coating on its upper face is non-tacky to allow rolling up without adhesion.
For permanent indoor or outdoor use, panels of the above described upper face material are provided with underlying panels of closed cell, waterproof plastic foam having negligible expansion and contraction characteristics. Both the upper surface and the underlying foam are stretched over and secured to curbing defining the perimeter of the field so as to prevent bunching during use.
The method of permanent installation according to the invention includes the step of stretching a surface as hereinbefore described over a base area.
10 Claims, 5 Drawing Figures PLAYING COURT SURFACE AND METHOD OF CONSTRUCTING SAME CROSS-REFERENCE TO CO-PENDING APPLICATION This application is in part a continuation of copending application, Ser. No. 794,641 filed Jan. 28, 1969, now US. Pat. No. 3,577,894 issued Jan. 26, 1971 and of Ser. No. 113,915 filed Feb. 9, 1971, now abandoned.
FIELD OF THE INVENTION This invention is concerned with a novel surface use-' ful for playing courts. This surface is characterized by its portability and/or its ability to be used immediately after a precipitation by simply removing water therefrom, the surface in question not requiring any draining means.
As used hereinafter, the term playing court refers primarily to a site on which some sporting activity is carried out. However, the novel surface of the invention can be employed wherever its characteristics are desirable, whether or not sports are involved.
BACKGROUND OF THE INVENTION The present invention represents a solution to two troublesome problems which have always confronted users of playing surfaces. One is the long felt need to have such areas in non-slippery condition as soon as possible after precipitation without having recourse to considerable manpower or other means to place the playing area in acceptable condition. The other problem is the provision of a standard and uniform surface which will eliminate the variations in playing performance inherent in the diversity of playing surfaces. What is meant here is that, for example, in tennis, certain players throughout the history of the'game have performed well on clay and'poorly on grass or wood, etc.
The prior art reveals that the attempts made to provide synthetic playing surfaces have generally been, centered on the concept of duplicating grass. As shown in US. Pat. Nos. 3,332,828; 3,157,557; 2,515,547; 3,390,044; 3,513,061; 3,433,137; 3,400,644 and 3,513,062, these artificialsurfaces consist of a backirig or nap from which extends a plurality of filaments or flexible fibers simulating grass. Generally these surfaces are too heavy to be portable, are difficult to dry and do not provide acceptable ball-skid-speed'characteristics. They are uncomfortable in hot weather because they retain heat owing to their construction.
SUMMARY OF THE INVENTION Broadly stated, the invention resides in the concept of a playing area including a flexible upper surface having thereon an elastomeric coating giving it the desired ball-skid-speed characteristics and wear resistance.
In a more specific aspect, the invention resides in a rollable, portable, playing area consisting of a plurality of elements having the above described characteristics, to which has been secured an undercushion of a sturdy, low density plastic foam which has a high coefficient of friction and substantially permanent tack relative to any surface on which it may be placed.
.In another aspect, the invention consists in the concept of an outdoor playing area, such as a tennis court, in which the above described playing surface is 2 a stretched together with an underlayer of plastic foam over a pretreated site.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like reference characters indicate like parts or features:
FIG. 1 is a diagrammatic view of a portable playing area, such as a tennis court, in accordance with this invention. 7
FIG. 2 is a cross-section through line 2-2 of FIG. 1.
FIG. 3 is a diagrammatic view of an outdoor tennis court in accordance with the invention.
FIG. 4 is a view along line 4-4 of FIG. 2 showing also means for stretching a court during construction.
FIG. 5 is a detailed view showing how individual panels of cushion and playing surface materials are secured.
DESCRIPTION OF SIECIFIC EMBODIMENTS Portable Court FIG. 1 shows a reliable, portable tennis court according to the invention. In this embodiment, the court consists of eight matched panels 1-8 which can be wound on amandrel or core when not in use. The upper or playing face 10 of each panel consists of a rugged syn-,
' thetic plastic fiber pretreated with a first coating agent sheets, polytetrafluoroethylene and the like. Preferred coating agents include elastomers such as acrylic polymers sold by Rohm and Haas Co., Philadelphia, Pa. under the trademarked name of Rhoplex 8-15 or thermo setting elastomeric polyurethanes, such as those sold by Raffi & Swanson, Inc., Wilmington, Massachusetts, under the trademarked name of DURANE L--8384--AG10.v Continuous films of the acrylic polymer emulsions can bedeposited or knife coated under normal temperature conditions without the addition of 7 plasticizers. Thermosetting urethanes are knife-coated under temperatures of 325 Fwith a dwell time of 60 seconds necessaryforc'uring. Films from these materials have intermediate hardness and permanent flexibility. If desired, pigment materials can be incorporated with the elastomeric emulsion or solution. The amount of elastomer used makes it possible to obtain a surface which duplicates the ball speed characteristics of clay,
grass, etc. v
To the underside of the playing surface 10 is knife coated, then heat laminated a sturdy, low density resilient plastic foam layer. 12 which fora tennis court would have a thickness of about one-eighth inch. This cushion layer gives the desired sound and height of bounce of the ball. The cushion consists of foamed polyvinyl chloride which has a high coefficient of friction and a-permanent tack such that thepanelscan hold firm independently to floors 14 of polished wood, or slick concrete and terrazzo, under all playing conditions without securing means of any description. Polyvinyl chloride foamed onto the playing surface has of the material which has the best tack relative to the surface on which it will be placed.
The above-described court can be laid out by two men in a matter of a few minutes. Next a centerstrip assembly for the net 18 having a buckle and a shaped leadweight 16 for anchorage is placed on the court. The net posts 20 are of aluminum tubing. The posts fit in a floor plate assembly 21 from which extend plastic coated stainless steel wire stays 23. Preferably for portable courts, the net posts will consist of weighted base weighing about 175 lbs. having at one end apair of wheels for rolling the assembly and on the other end an aluminum tube on which is mounted a right angle fitting holding the net post. Under the fitting is provided a foldable member fitted with rubber tips and feet to protect the floor surface. A steel wire connects the upper part of the post to a hook on the base. Lines can be painted on the playing surface or sprayed thereon.
The method of constructing the court will then consist of providing a plurality of panels such as panels 1-8 shown in FIG. 1 and of placing them on a base surface in abutting relationship. The tackiness of the panels underside is sufiicient to hold the court in assembled condition during use. However, where required by the na ture of the game or by other factors, the panels can be secured together temporarily on their underside by adhesive tape or solvent activated Lycra" bands and the like.
In a typical embodiment of the invention a portable, rollable tennis court was made of eight 9% X 48 feet panels, each weighing 125 lbs. for a combined total, respectively, of about 3,650 sq. ft. and 1,000 lbs. When not in use the panels are rolled up on individual polyethylene roller cones 3 inches in diameter and the rolled up panels are stored on a 1 inch X 30 inch X 8 ft. plywood dolly with five 4 inches heavy duty casters.
PERMANENT OUTDOOR COURT A permanent outdoor tennis court is shown in FIG. 3. To aid in removing water from the court after a rain, it is preferred that the court have a slight pitch or slope relative to the horizontal such'as a pitch of 1 inch per feet of court. Similarly, to insure rapid removalof water by brushing, squeegeeing or the like, especially if there are several courts together, each court should have a slight crowning as indicated at 22 in FIG. 3 so that water will drain off to either side. While the sloping of the court can be made from one end to the other, it is apparent that the court could also slope from the middle toward each end if the surrounding land is perfectly flat. If the surrounding land is not perfectly flat, then the slope would normally preferably run with the slope of the land. Thus the court will drain to either side and longitudinally in the preferred form.
In all forms of the permanent outdoor court described herein, the soil below the court is rough graded and the base is then built on the rough graded raw soil material.
A base of substantially rigid material is provided over the rough graded raw soil surface and this base will normally slope relative to the horizontal. If the base is to be formed of stabilized soil, the sloping and crowning thereof can be carried out with the base material alone, but it will be preferred to provide at least some of the sloping and crowning with the rough grading. Of course, if special water and snow removal means are always available, such as blowers or squeegees, the sloping and crowning of the court are not necessary.
In the event an existing clay or composition playing area is being converted to a playing area in accordance with this invention, it should be carefully replaced with sharp sand or small grit, as will be described below, which is stabilized with an emulsion.
Generally, in accordance with the method of the invention, the raw soil is cleaned of all carbonaceous material and compacted to percent Proctor density. If the local soil conditions require, fill material is either substituted or admixed with the existing material to achieve the above-stated compaction of the subbase. Over the compacted sub-base 24 is spread enough compactible material to achieve full coverage of the rough graded plane differentials. The overall playing area is then perfected to a graded plane with surface depth differentials not to exceed one-tenth inch per each sq. ft. segment, using transit and straight-edge controls. The base surface 26 is loosely compacted by lightly rolling with a lightweight roller and then sprayed by means of a hose with a sufficient quantity of a soil stabilizing plastic emulsion which will provide when cured, the equivalent of a 95 percent Proctor density compaction. A preferred stabilizer for this purpose is Rohm & Haas Rhoplex AC 34 an acrylic resin emulsion.
What is desired here is to provide a substantially rigid and impermeable base. Any lasting and effective waterproofing means can be used for-this purpose. Preferably the base surface should neither allow the penetration of water from above nor allow upward flow from the ground below.
Either before or after the base is perfected trenches or flumes 28 are dug around the perimeter of the playing court and also across the width of the center for a tennis court (corresponding to the line of the netposts 20). The depth of the trenches is about 12 inches and they are filled with Masons sand or other frostinhibiting material 30 to a depth of about 8 inches. Next 2 inches X 6 inches redwood curbing members 32, set on their narrow edges are embedded into the trench-fill material 30 so that the top side of the curbing constitutes, and is flush with, the finished base elevations of the court. The curbing is secured in the trench by staking with 1% inch X 30 inches concrete reinforcement rods 34 at not less than 4 feet intervals.
Panels of ionomer plastic foam, a product of Gilman Bros, Gilman, Connecticut, with a thickness in the range of one-eighth to one-fourth inch density in the range of 3 to- 6 pounds per cubic foot are joined together over the finished base area by heat welding adjoining panels. Similarly, the panels can be butted together and joined by means of adhesive strips secured on their top sides and undersides.
Plastic foam material 12 one-eighth inch to threeeighth inch thick is closed cell and waterproof, with negligible expansion and contraction characteristics and is used to protect the overlying playing surface from contact with water which might seep upwardly through any void left unfilled in the finished base and ing.
The foam material is then laid over the entire area I also to protect the playing surface from any frost heav- Each panel is stapled first at one lengthwise end by staples 38 and stretched taut by pulling manually at the opposite end and stapling that end. The process is then repeated by first stapling across one width and stretching each panel away from the stapled end in turn and finally stapling the end of the last panel away from that stapled end.
Next panels comprising the playing surface are prepared as indicated above in the case of the portable court.
It should be noted that the playing surface is impervious to microbacterial organisms. It has been made waterproof by treatment by the elastomer. These features in combination with those of the foam layer make it impossible for the playing surface to become wet or to retain water.
The panels are laid out and butted together, then joined on their underside with Dacron tape 50 which has been procoated with aliphatic elastomeric urethanes such as that sold by Custom Chemicals, East Paterson, New Jersey, under the name of U.I'.C. 396. The adhesive on the tape is solvent activated with either Acetone or M.E.K.
The panels are then pneumatically staped with 1 inch No. 16 guage galvanized staples to the sides of the curbing over the foam at one end. Each panel is then stretched against the end which has been secured using a pair of 2% X 10 ft. channel irons members 40 in which a countersunk 2 inches carpet stripping members 41 with studs 42 which are passed through the-end of the panel as shown in FIG. 4. The channle irons which hold the stripping and the panels are held in hinged clamp 43. A cable 44 connects the assembly to a ratchet mechanism by means of which the panel can be pulled taut to about 3,000 pounds per sq. ft. pressure depending on the type of surface. This tension eliminates all ripples in the surface material. Generally such ripples occur mainly in the lengthwise direction so that most of the stretching is effected in that direction. With the panelstill under tension, it is stapled to the top of curbing 32. Next, tension on the end of the panel is released-and the stretching apparatus is removed. As shown in FIG. 4, the ends of the panel 10, are folded down over foam 12 and stapled to'the sides of the curb,-
lt will be appreciated that several stretching techniques and various stretching apparatus may be resorted to in the practice of the present invention. Choice of such means will be dictated generally by the amount of space surrounding the area where the playing surface is to beinstalled and available for the stretching apparatus as well as by the size of the panels to be stretched. In this latter respect, where for example 60 ft. panels are to be stretched, it has been found advantageous to first stretch a 30 ft. middle section lengthwise and widthwise, thus leaving the corners on each side of this section loose, and then pull these corners diagonally before securing as above described.
Stretching can also be effected by means of conventional carpet stretching apparatus used for laying down tackless Stripping.
.its nearness of the wall, would not be played on; and
thento use 10 foot lengths of cleated stripping welded to a hydraulic jacking device which creates opposed stretching effects widthwise and endwise. Here, one parallel curbing installation would be set at a sufficient distance froma wall to enable the stretching device to extend past the curbing. A distance of about 12 inches suffices.
It should be noted that with the playing court of this invention, all creases, bumps, ridges and bunching are prevented even under strenuous conditions of use. In the case of the portable court, this is achieved by the substantially permanent tackiness of the undersurface thereof. In the other embodiments of the invention, those hazards are prevented by the fact that the playing surface and the foam cushion are under tension.
It will be understood that many modifications and variations encompassed by the appended claims will occur to those skilled in the art. Thus it will be evident that the foam layer 28 can be glued or bonded to the upper surface and that both can be stretched and secured together.
With the construction described, the playing surface requires no draining means whatsoever and may be used immediately after tain by simply brushing or squeegeeing thewater away from the surface.
As used herein, the term elastomerirefers to rubbery, high molecular weight polymers.
I What I claim is:
l. A playingcourtcomprising a substantially flat, flexible upper layer, formed of a plurality of panels, said panels having foamed thereunder a layer of tacky closed cell plastic foam, said panels consisting of a material selected from the group consisting of woven, needle punched, or felted, nylon, acrylic fibers, polyester, canvas, polypropylene, nylon-reinforced polyvinyl chloride, polyurethane sheets, polytetrafluoroethylene, and mixtures thereof; said plastic foam being selected from the group consisting of polyethylene, polystyrene, polyvinyl chloride and mixtures thereof, said foam giving said court the desired ball bounce height, and a waterproof, elastorneric coating on said upper layer for giving said court the; desired ball-speed characteristics.
2. A court according to claim 1, wherein said plastic foam is of a plastic material giving the underside of said court permanent tackiness whereby said court can hold firmly and independently to any surface under all playing conditions without any securing means.
Installation of a permanent court in a space surrounded partially or completely by a retaining wall or solid fence can present problems. In this case, it has been found practical to initially secure permanently one end of the upper surface panels over the foam near one of the walls of the hall since that end, because of 3. A court according to claim 1 wherein said panels are secured on their undersides; by strips of tape, said tape having a coating of aliphatic elastomeric urethane adhesive.
4.'A court according toclaim 1, including a frame defining the periphery of said court, said cushion means and said flexible member being stretched over said frame, and over a rigid base.
5. A court according to claim 4, including a trench along the periphery of said court, said frame lying in said trench and defining the height above ground of said court.
6. A court according to claim 4, wherein said base comprises substantially rigid material containing soilstabilizing means and having a compaction of at least percent Proctor compaction.
7. A court according to claim 4, wherein said cushion means and said flexible member each consist of a pluproof, elastomeric coating consists of an acrylic polymer.
10. A court according to claim 1, wherein said waterproof coating consists of a thermosetting polyurethane material.