3,786,011 United States Patent 0 ice Patented Jan. 15, 1974

l 2 3,786,011 Accordingly, the invention comprises a synthetic pitch 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 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 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 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 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 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 , 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 , 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. 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 ______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 rubbers. Pre Unplasticized polyvinyl chloride ______26 ferred rubbers are nitrile rubbers which are copolymers of Commercial dioctyl phthalate plasticizer ______18 acrylonitrile with butadiene or isoprene or similar dienes. Commercial dioctyl adipate plasticizer ______2 It is believed that the amount and nature of the bounce 25 Styrene-butadiene rubber ______10 obtained will vary with the amount of the rubber present Polymer mix comprising 70% nitrile rubber (34% and the type of rubber present. Accordingly, the amount acrylonitrile, 66% butadiene) and 30% un and type of rubber may be varied in order more ac plasticized polyvinyl chloride ______10 curately to reproduce the bounce characteristics of the Asbestos ?bres ______7 grass surface it is intended to simulate. A preferred 30 Whiting ______.._ 23 amount of rubber is between 3% to 10%. Calcium stearate ______2 The synthetic pitch or ?eld may contain a pigment, Green pigment ______2 preferably green to simulate grass. The synthetic pitch or ?eld may contain conventional lubricants, stabilizers and The shredded conveyor belt contains about 50% ?bres, mostly polyester, 25 % polyvinyl chloride and 25% processing aids. 35 The pitch or ?eld may be compounded by mixing the liquid polyester plasticizers. The conveyor belt is shredded constituents in a conventional way at an elevated tempera or comminuted in a Z-blade mixer, to a size mostly less ture, for example between about 120° C. and 160° C., in than about 10 mm. The “alphanol” is a mixed C-alkylated a Banbury mixer. The pitch or ?eld may then be formed alcohol, a cut of about C7 to C9 being used. by extrusion through a roller die to produce a smooth 41-0 We claim: synthetic pitch or ?eld. Alternatively the pitch or ?eld 1. A composition closely simulating a grass playing may be compression moulded. The synthetic pitch or surface in its bounce characteristics useful as the pitch or ?eld may, advantageously, be of such a thickness that it ?eld for cricket, tennis and like ball games in which can be cut into pieces, the edges of which can abut one games a spinning 'ball bounces on a grass playing surface another so that, when lying on a smooth surface, a said pitch or ?eld containing 25% to 75% of a plasticized smooth pitch or ?eld is formed. The individual pieces 45 polyvinyl chloride material comprising polyvinyl chlo may be interchanged in order, as described, to facilitate ride material and plasticizer wherein the proportion of the even wear of the pitch or ?eld. A suitable thickness plasticizer to polyvinyl chloride material is greater than of the synthetic pitch or ?eld is between 2 mm. and 15 1 to 2, 5% to 20% of a ?nely divided ?brous material, mm, about 5 mm. being preferred. 3% to 10% of a natural or synthetic rubber, compatible Typical compositions for synthetic pitches or ?elds are with the plasticized polyvinyl chloride material in the set out in Tables 1 to 5 below. In each case the pitch quantity employed, and 20% to 40% of a ?nely divided or ?eld may be manufactured by compounding the con particulate ?ller all parts being by weight of the total of stituents in a Banbury mixer at a suitable temperature so the total weight of the composition. that a homogeneous mixture is formed. The homogeneous 2. The composition of claim 1 wherein the polyvinyl mixture may be extruded through a roller die to form a chloride material is a copolymer of vinyl chloride with sheet. Testing is carried out empirically. a comonomer, said copolymer containing at least 70 mole percent of vinyl chloride monomer. TABLE 1 3. The composition of claim 2 wherein the comonomer Unplasticized polyvinyl chloride ______29 is vinylidene chloride or vinyl acetate. Dialphanol phthalate plasticizer ______21 4. The composition of claim 1 wherein the polyvinyl Finely divided polyester ?bres ______7 chloride material is a homopolymer of vinyl chloride. Acrylonitrile-butadiene rubber ______5 5. The composition of claim 1 wherein the synthetic China clay ______33 rubber is a chloroprene rubber, a styrene-butadiene rub Pigmentary titanium dioxide ______1 ber, an ethylene-propylene rubber, an acrylonitrile Calcium stearate ______2 65 butadiene rubber, or an acrylonitrile-butadiene-styrene Green pigment ______2 rubber. 6. The composition of claim 1 wherein the polyvinyl TABLE 2 chloride material is plasticized with a liquid ester Unplasticized polyvinyl chloride ______25 plasticizer. Dialphanol phthalate plasticizer ______17 70 7. The composition of claim 6 wherein the liquid ester Shredded conveyor belting ______15 plasticizer is a monomeric dialkyl ester of a dicarboxylic Acrylonitrile-butadiene rubber ______5 acid. Whiting (coated chalk) ______34 8. The composition of claim 7 wherein the dicarboxylic Calcium stearate ______2 acid is a phthalic acid, succinic acid, adipic acid, azelic Green pigment ______2 75 acid, suberic acid, sebacic acid or a mixture thereof. 3,786,011 5 6 9. The composition of claim 8 wherein the alkyl group Percent is derived from a straight or branched chain alkanol Unplasticized polyvinyl chloride ______About 29 selected from butanol, 2-ethylhexanol, 3,5,5-trimethyl Dialkylated alcohol phthalate plasticizer con hexanol, heptanols, decanols, dodecanols and tridecanols. taining 7—9 carbon atoms ______.__ About 21 10. The composition of claim 6 wherein the ester is a Finely divided polyester ?bers ______About 7 triphosphate. Acrylonitrile-butadiene rubber ______About 5 11. The composition of claim 6 wherein the ester is China clay ______About 33 a substantially straight chain polyester having a molecular Pigmentary titanium dioxide ______About 1 weight of between about 700 and about 2000. Calcium stearate ______.._ About 2 12. The composition of claim 1 wherein the ?ller is 10 Green pigment ______About 2 chalk or clay. 13. The composition of claim 1 wherein the ?nely di References Cited vided ?brous material comprises ?bers having a mean UNITED STATES PATENTS length of less than about 15 mm. 3,399,103 8/ 1908 Salyer et a1. ______260-899 14. The composition of claim 13 wherein less than 15 25% of ?bers have a length between 15 mm. and 25 mm. 3,541,061 11/1970 Heiberger ______260-899 15. The composition of claim 14 wherein the ?brous 3,670,056 6/1972 Heiberger et a1. __ 260-23 X A material is an organic ?brous material. DONALD E. CZAJA, Primary Examiner 16. The composition of claim 15 wherein the organic ?brous material is cotton cellulose polyester or polyamide. 20 R. W. GRIFFIN, Assistant Examiner 1.7. The composition of claim 1 including also a green pigment. U.S. Cl. X.R. 18. The composition of claim 17 comprising: 260-4; 17.4 CL, 23 X A, 30.6 R, 31.6, 41 R