United States Patent 0 Ice Patented Jan
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3,786,011 United States Patent 0 ice Patented Jan. 15, 1974 l 2 3,786,011 Accordingly, the invention comprises a synthetic pitch POLYVINYL CHLORIDE RESIN COMPOSITION or ?eld for cricket, tennis and like ball games containing CLOSELY SIMULA'I'ING A GRASS PLAYING SURFACE IN ITS BOUNCE CHARACTERISTICS 25% to 75% of plasticized polyvinyl chloride, 5% to David Watkin Price and Ronald Sidebottom, Cheltenham, 20% of a ?nely divided ?brous material, 0% to 20% of Murray George Briscoe, Eckington, and Ronald Charles 5 a natural or synthetic rubber compatible with the plasti Moore, North Weald, England, assignors to Coal In cized polyvinyl chloride, and 10% to 60% of a ?nely di dustry (Patents) Limited, London, England vided particulate ?ller, all parts being by weight of the No Drawing. Filed June 1, 1971, Ser. No. 149,002 total weight of the composition. Int. Cl. C08c 9/14; C08f 29/24 Any conventional polyvinyl chloride may be employed U.S. Cl. 260-22 CB 18 Claims in the present invention. Copolymers of vinyl chloride with other monomers, which copolymers have physical ABSTRACT OF THE DISCLOSURE properties similar to that of conventional polyvinyl chlo ride, and desirably contain at least 70 mole percent, pref A synthetic pitch or ?eld for cricket, tennis, and like erably at least 80 mole percent, of vinyl chloride mono ball games is provided, which, in contrast to previous pro 15 mer, may also be employed. Mixtures of the copolymers posed pitches, closely simulates grass, particularly in its with homopolymer may be employed. Suitable comono bounce characteristics, especially for spinning balls. The mers that may be employed include vinylidene dichloride synthetic pitch or ?eld contains 25% to 75% of plasticized and vinyl acetate. polyvinyl chloride material, 5% to 20% of a ?nely di Any suitable conventional plasticizer for polyvinyl chlo vided ?brous material, 0% to 20% of a natural or syn ride may be employed to plasticize the polyvinyl chloride. thetic rubber, preferably a nitrile rubber, and 10% to 60% Suitable plasticizers that may be employed include was of a ?nely divided, preferably low density ?ller, for ex conventional, preferably liquid, ester plasticizers, includ ample chalk and clay, and may also contain a green pig ing the diesters of aliphatic and aromatic dicarboxylic ment. acids, for example the phtha'lic acids, succinic acid, adipic 25 acid, azelic acid, suberic acid, sebacic acid and homolo The invention relates to improvements in or relating to gues thereof and mixtures of such acids. The esters may synthetic pitches or ?elds for cricket, tennis and like ball be of aromatic alcohols, or of straight or branched chain 1games and to methods of manufacturing such pitches or alkanols, for example butanol, 2-ethylhexanol, 3,5,5-tri elds. methylhexanol, heptanol, decanol, dodecanol, various Synthetic pitches or ?elds have been made from various branched and straight chain tridecanols and benzyl alco materials, particularly woven and non-‘woven ?brous ma hol. Other types of plasticizers that may be employed in terials. These materials have been found suitable for clude the alkyl phosphates, particularly the trialkyl and games in which the bounce of the ball is relatively unim triaryl phosphates. portant. Such surfaces used hitherto have not always Low molecular weight substantially straight chain poly proved entirely suitable, and not having, in many cases, 35 mers may also be employed, for example polyesters hav bounce characteristics, particularly in relation to spinning ing molecular weights of between about 700 and about balls, suf?ciently close to that of natural grass. In other 2000, derivable, for example, from the reaction of dicar cases solid materials have been employed, for example boxylic acids with diols. Suitable dicarboxylic acids in- wood, but such materials is only satisfactory, on the clude those listed above; suitable diols include ethylene ground of expense, for games in which there is relatively 40 glycol, propylene glycol, butan-1,4-diol, butan-2,3-diol and small pitch or ?eld, for example tennis. Such solid ma 2,2-dimethylpropan-l,B-diol. Suitable polyester plasticizers terials also have the disadvantage that the bounce char include also those derivable by the reaction of a monohy acteristics are not always suf?ciently close to that of grass. droxymonocarboxylic acid, for example 6-hydroxycaproic For these reasons, such surfaces as have been generally acid. Polymeric esters are preferably terminated by a non employed hitherto have not proved entirely satisfactory 45 reactive group, for example by the introduction of a for winter practice in preparation for summer activities. monohydroxyalcohol. Other types of plasticizer include In games such as cricket, the balls tend to bounce on a epoxidized esters for example oleate esters and soya bean relatively small area of the pitch or ?eld, which small oil, and those based on trimellitic acid or on pentae area tends to wear, while the remainder of the surface rythritol. of the pitch or ?eld is relatively unworn. The pitch or ?eld 50 Examples of the aforementioned types of plasticizers then would need to be discarded, while the majority of the include di-n-butyl phthalate, di-Z-ethylhexyl terephthalate, surface thereof would still be useable. di-iso~octyl phthalate, didodecyl phthalate, butyl benzyl The present invention provides a pitch or ?eld which phthalate, di-iso-butyl adipate, di-n-octyl sebacate, the di has bounce characteristics closer to that of natural grass azelate of mixed straight chain cuts of ‘C9 to C11 alkanols, than those pitches or ?elds of an equivalent cost hitherto 55 butylene phthalate polyester, ethylene terephthalate poly employed, particularly in relation to the bounce charac ester, propylene adipate polyester, polycaprolactone, teristics of spinning balls and for fast and medium bowl ing in cricket. The pitch or ?eld of the present invention epoxidized octyl oleate, and trixylyl phosphate. may easily be made in parts which can be interchanged Any convenient ratio of plasticizers to polyvinyl chlo so that the whole area of the pitch or ?eld can be made ride may be employed in order to ensure that, under the to wear evenly, and the pitch or ?eld can be removed for 60 conditions under which it is proposed to use the pitch or temporary storage. The pitches or ?elds of the present ?eld, the pitch or ?eld will be su?iciently ?exible. As a invention do not normally need to be bonded to the sur guide, a proportion of less than 2 parts polyvinyl chloride face on ‘which they are placed but can be placed on a to 1 part of plasticizer will often be convenient, and a ?at surface. They have the further advantage that they ratio of about 1 is preferred. require no maintenance. 65 Any suitable ?bre may be employed in the present in In use, the pitches or ?elds remain true, with no bad vention. Such suitable ?bres are, in general, organic ?bres, bounces, and do not normally re?ect light to such an ex either natural or synthetic, for example cotton, cellulose, tent that gives rise to an unacceptable amount of glare. polyamide and polyester ?bres. By “?nely divided The pitches or ?elds are resilient and certain types of 70 ?brous material” it is meant that the ?bres should boots or shoes with studs can be worn without causing desirably have a length of less than about 15 mm. and serious damage. preferably less than 10 mm. It will be understood, how 3,786,011 3 4 ever, that a portion of the ?bres, preferably less than TABLE 3 25%, may be longer than 15 mm., but such a portion Unplasticized vinyl chloride/vinyl acetate copolymer are Preferably shorter than about 25 mm. The ?bres may (15% vinyl acetate) _______________________ __ 20 be compounded in a mixture with the polyvinyl chloride Dialphanol phthalate plasticizer ________________ __ 17 material, as, for example, is the case if the source of the Acrylonitrile-butadiene rubber _________________ __ 5 ?bres is shredded or comminuted conveyor belting or Shredded conveyor belting ____________________ __ 15 oil-cloth or the like, or the ?bres may be added separately, Whiting ____________________________________ __ 34 for example as a ?oc. Calcium stearate ____________________________ __ 2 Any ?nely divided particulate ?ller may be employed Green pigment ______________________________ __ 2 for the pitches or ?elds of the present invention, but it Extender (chlorinated parat?ns containing 42% is preferred to use ?llers having a relatively low density, for example ?nely divided chalk, clay and like minerals. chlorine) ________________________________ __ 5 Desirably the quantity of ?ller employer is less than 50% TABLE 4 and a preferred quantity of ?ller is between 20% and Plasticized polyvinyl chloride (40% plasticizer) ____ 47 40% by weight. Finely divided cotton ?bres ____________________ __ 10 Any natural or synthetic rubber may be employed in Nitrile rubber _______________________________ __ 5 the present invention, provided that it is compatible with Chalk Filler ________________________________ __ 34 the polyvinyl chloride material in the quantity employed. Green pigment ______________________________ __ 2 Suitable rubbers include chloroprene rubbers, isoprene Lubricants and stabilizers _____________________ __ 2 rubbers, buna rubbers, styrene-butadiene rubbers, ethyl— one-propylene rubbers, acrylonitrile-butadiene-styrene rub TABLET 5 bers and chlorosulphonated polyethylene rubbers. Pre Unplasticized polyvinyl chloride ________________ __ 26 ferred rubbers are nitrile rubbers which are copolymers