IMPROVEMENTS IN OR RELATING TO TENNIS BALLS

Abstract

A tennis ball comprising a hollow core and a cover, the core being formed from a composition including rubber, in which the composition comprises recycled tennis ball material.

Claims

1. A tennis ball comprising a hollow core and a cover, the core being formed from a composition including rubber, in which the composition comprises recycled rubber.

2. A ball as claimed in claim 1, in which the core composition comprises a proportion of recycled rubber and a proportion of unrecycled, new or virgin rubber.

3. A ball as claimed in claim 1, in which at least some of the recycled content is derived from tennis balls.

4. A ball as claimed in claim 3, in which the recycled content comprises tennis ball fibres from the recycled coatings on the recycled tennis balls.

5. A ball as claimed in claim 1, in which the core comprises at least one rubber selected from a group of rubbers consisting of: natural rubber, polybutadiene, isoprene, styrene-butadiene rubber and mixtures thereof.

6. A ball as claimed in claim 1, in which the ball has a generally uniform outer surface consisting of a fabric cover.

7. A ball as claimed in claim 1, in which the ball is a pressurised tennis ball.

8. A ball as claimed in claim 1, in which the ball is a pressureless tennis ball.

9. A tennis ball as claimed in claim 1, the tennis ball incorporating recycled tennis balls, the ball comprises: a) moulded ball core half shells joined to form a ball; and b) a cloth coating on the ball.

10. A ball as claimed in claim 9, wherein the core half shells comprise a core formulation comprising fibres from the recycled coatings on the recycled tennis balls.

11. A ball as claimed in claim 9, comprising thermally expanded microspheres.

12. A tennis ball according to claim 1, the tennis ball incorporating recycled tennis balls, the ball comprises: a) moulded ball core half shells joined to form a ball; and b) a cloth coating on the ball; c) wherein the core half shells comprise a core formulation comprising: i) fibres from the recycled coatings on the recycled tennis balls; and ii) kieselguhr.

13. (canceled)

14. A process of making a hollow rubber ball which incorporates recycled rubber balls comprising the steps of: a) forming a batch of said recycled rubber balls and reducing it to granules by maceration and/or grinding; b) combining the recycled granules with virgin rubber and, optionally, other additives to form a core formulation; c) producing ball core half shells by forming the core formulation in a suitable mould; d) curing the formulation at a temperature of from 120-180° C.; e) joining the half shells to form a ball core and curing the ball core.

15. A process according to claim 14, wherein the cured ball core is coated with a cloth covering to form a new tennis ball.

16. A process according to claim 13, wherein the additives are adjusted according to type or quantity depending on the results of the testing to conform the new tennis ball to a set of regulations.

17. (canceled)

18. A process according to claim 13, wherein the additives include an expanding thermoset resin.

19. A process according to claim 13, wherein the additives include kieselguhr.

20. (canceled)

21. A process according to claim 13, wherein the recycled rubber balls are partially or wholly cloth covered tennis balls.

22. A ball according to claim 1, wherein the core formulation comprises from 10-80% by weight, preferably from 20-50% by weight, more preferably from 30-50% by weight of recycled rubber balls.

23. (canceled)

24. A formulation for the use of recycled material in pressurised tennis balls or in non-pressurised tennis balls, comprising: recycled tennis ball material natural rubber synthetic rubber vulcanisation accelerator rubber process oil.

25. (canceled)

Description

EXAMPLE 1.1

[0176] Standard Formulation as Describe Above (“Base Mix”) Plus: [0177] 100 pph recycled tennis ball material based on the rubber hydrocarbon of standard formulation (i.e. there is approximately a 1:1 ratio of recycled material and unrecycled material in this embodiment) [0178] 1.5 pph additional Sulphur based on the recycled tennis ball material added [0179] 1.5 pph additional DPG based on the recycled tennis ball material [0180] 1.5 pph additional CBS based on the recycled tennis ball material [0181] 3 pph non staining oil based on the recycled tennis ball material [0182] 6 pph keiselguhr based on the standard mix RHC

[0183] It is noted that the term pph is not a % value. The RHC of the standard formulation sets a value of 100 pph. The recycled content is set at 100 pph in this embodiment (i.e. a 1:1 ratio). In this embodiment the recycled tennis ball material sets a value of 100 pph, then other components are quantified relative to this value. For example if 40 kg of rubber is used, then that defines a 100 pph value. 1 pph, for example, would then be 0.4 kg. As a further example, 1 kg of recycled tennis ball recycled material may be added. 1.5 pph of DPG would therefore be 15 g i.e. this is based on the recycled tennis ball material and not the total rubber content. It will be appreciated that the pph content for the additives could be set by the unrecycled rubber content and/or by the recycled material content.

[0184] The oil may be rubber process oil, such as paraffinic oil. The oil “wets” the surface of the crumbed rubber, allowing it to incorporate more easily.

[0185] This formulation contains both recycled and non-recycled rubber.

[0186] In some embodiments, for example, the rubber is provided in crumbed form, for example up to 1 mm crumbs.

[0187] In this embodiment an added amount of sulphur is used compared to a standard tennis formulation. This is to help re-process the aged rubber, which will have oxidised to a degree over time and therefore will have lost some properties.

[0188] Accelerators are included to help with vulcanisation.

[0189] Keiselguhr is a semi-reinforcing filler. Diatomaceous earth, diatomite or kieselgur/kieselguhr is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. Typically it has a particle size ranging from less than 3 μm to more than 1 mm, but typically 10 to 200 μm.

[0190] As crumbed recycled tennis ball material varies in many ways it has been found that kieselguhr helps to provide more consistency. It has also been found that the addition of keiselguhr affects the bounce of balls less than some other fillers.

[0191] In some embodiments whole tennis balls, including the felt/cloth covering, are used to provide recycled content.

[0192] This formulation is moulded into half core shells and combined and covered with cloth and tested. Test Balls produced from this formulation results weight 58 grams, Rebound 54″, Compression 270 are to ITF balls standards.

[0193] Test balls meeting the required standards have been produced using 900 pph of recycled tennis ball material, based on the standard formulation RHC. At this level the % weight of recycled material comprises 75% of the complete ball.

[0194] Possible useful range of recycled tennis ball material is 10-900 pph based on RHC.

[0195] Further formulations for the use of recycled material in pressurised tennis balls

EXAMPLE 1.2

[0196] Standard Pressurised Formulation Plus 100 pph of Recycled Material

TABLE-US-00005 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test Ball   55 g 0.290 51-52 6.7 results

[0197] This produces a ball that is out of specification in regards to the rebound and weight. A series of amendments were carried out.

[0198] The Final Corrective actions taken: [0199] (a) Ratio pph of natural rubber and polybutadiene reversed from 66 \ 34, to 34 \ 66 [0200] (b) Keiselghur added. [0201] (c) Increased amounts of curatives.

[0202] Formulation 1.2 with Corrective Actions Included:

TABLE-US-00006 Natural Rubber 34 pph Polybutadiene 64 pph Zinc Oxide 4 Stearic Acid 1 Antioxidant 1 Clay 29 Light mag carbonate 38 MC Sulphur 5.25 DPG 3.76 CBS 3.76 TMTD 0.25 Recycled tennis ball material 100 Rubber process oil 3 Keiselguhr 6

TABLE-US-00007 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test Ball   58 g 0.270 54″ 6.67 results

[0203] This produces a ball that meets ITF ball standards.

EXAMPLE 1.3

[0204] Standard Pressurised Formulation Plus 50 pph of Recycled Material.

TABLE-US-00008 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm)   56 g 0.300 56 6.6

[0205] This produces a ball that is out of specification in regards to the deformation. A series of amendments were carried out. [0206] The Final Corrective actions taken: [0207] (a) Keiselghur added. [0208] (b) LMC reduced [0209] (c) Sulphur decreased [0210] (d) Decreased amounts of curatives. [0211] (e) Natural rubber and Polybutadiene ratio changed,

[0212] Formulation 1.3 with Corrective Actions Included for Pressurised Tennis Balls

TABLE-US-00009 Natural Rubber 64 pph Polybutadiene 36 pph Zinc Oxide 4 Stearic Acid 1 Antioxidant 1 Clay 29 Keisulghur 38 Light mag carbonate 10 Sulphur 3.75 DPG 2.26 CBS 2.26 TMTD 0.25 Recycled tennis ball material 50

TABLE-US-00010 Deformation Weight compression? Rebound Size ITF SPECS 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test Ball   57 g 0.260 55 6.67

[0213] This produces a ball that meets ITF ball standards.

EXAMPLE 1.4

[0214] Standard Pressurised Formulation Plus 183 pph of Recycled Material,

TABLE-US-00011 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm)   58 g 0.180 52 6.54

[0215] This produces a ball that is out of specification in regards to the rebound and deformation. A series of amendments were carried out. [0216] The Final Corrective actions taken: [0217] (a) Keiselghur added. [0218] (b) LMC and Clay reduced [0219] (c) Sulphur increased [0220] (d) Decreased amounts of curatives. [0221] (e) Natural rubber and Polybutadiene ratio changed,

[0222] Modified Formulation 1.4, for Pressurised Tennis Balls

TABLE-US-00012 Natural Rubber 65 pph Polybutadiene 35 pph Zinc Oxide 4 Stearic Acid 1 Antioxidant 1 Clay 14 Keisulghur 66 Light mag carbonate 10 Sulphur 5 DPG 2.8 CBS 2.8 TMTD 0.5 Recycled tennis ball material 183

TABLE-US-00013 Deformation Weight compression? Rebound Size ITF SPECS 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test Ball   57 g 0.290 56 6.6

[0223] This produces a ball that meets ITF ball standards.

[0224] 2. Pressureless Balls

[0225] Use of Recycled Tennis Ball Material (e.g. Rubber and/or Cover) in Non-Pressurised\ Pressureless Balls

[0226] Recycled tennis ball material can be added to a non-pressurised ball formulation. Amounts are reduced compared with pressurised balls because pressureless balls have a thicker wall section and therefore a lower Specific Gravity than pressurised balls (which account for the larger percentage of balls sold in the world), the principle of which is discussed above.

[0227] It is more difficult as the recycled rubber\material will vary in weight and it will tend to be heavier than normal pressureless rubber, thereby limiting its use.

[0228] Pressureless formulations have been successfully modified by reducing the Specific Gravity, thereby allowing increased quantities of recycled ball rubber/material to be included.

[0229] Approximately one third of the tennis balls sold in the world are of the pressureless type, 10% other types (such as mini tennis balls, play & stay balls and junior tennis balls) the remainder are pressurised. Pressurised tennis balls are the same weight and size as non-pressurised balls, but approximately two thirds of the wall thickness/rubber volume, indicating a higher specific gravity. Batches of recycled material from these balls will be typically denser than normal pressureless ball rubber, thereby limiting its use in non-pressurised balls.

[0230] Amounts of recycled material it is possible to incorporate are reduced because pressureless tennis balls have a thicker rubber section than pressurised balls; therefore they have a lower Specific Gravity, than pressurised balls (as discussed above).

[0231] The present inventors have successfully modified and reduced the Specific Gravity of a standard pressureless ball formulation, thereby allowing a larger percentage of the heavier recycled material to be incorporated.

[0232] Some aspects and embodiments are based on the use of ingredients with lower specific gravities and the use of expandable microspheres and replacing or reducing ingredients of higher specific gravities.

[0233] A Standard non-pressurised\pressureless formulation of the prior art

TABLE-US-00014 Hi cis Polybutadiene 33 pph plus Natural Rubber 67 pph = 100 pph RHC High Styrene Rubber SS260 10 pph based on RHC Zinc Oxide 5 Stearic Acid 1 Antioxidant 1 Sulphur 3.75 Clay 20 Carbon Black 17 Wood flour 10 Oil 4 DPG 2.54 CBS 2.54

TABLE-US-00015 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm Specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test Ball   59 g 0.275 54 6.7 results

[0234] This produces a ball that meets ITF ball standards.

EXAMPLE 2.1

[0235] According to the Invention a Modified Pressureless Tennis Ball Formulation with Recycled Rubber Added

[0236] Hi Cis Polybutadiene 33 pph, Natural Rubber 67 pph=100 pph RHC

TABLE-US-00016 Zinc Oxide 2 pph Stearic acid 1 pph antioxidant 1 pph Sulphur 3.75 pph Carbon Black 12 pph Wood flour 15 pph Thermally expandable microspheres 5 Oil 12 pph Tennis ball recycled material 30 pph DPG 2.54 pph CBS 2.54 pph

[0237] The expandable microspheres may be, for example, the Expancel range, available from Boud Minerals.

[0238] The oil may, for example, be rubber process oil.

[0239] Example quantity of recycled rubber 50 or 100 pph of RHC (i.e. recycled content pph is based on non-recycled rubber content).

[0240] However, 5 to 200 pph based on RHC has been used producing balls to specification but the higher loading taking considerably longer to incorporate.

[0241] Formulations for Non-Pressurised Tennis Ball Containing Recycled Ball Material

EXAMPLE 2.2

[0242]

TABLE-US-00017 Natural rubber 67 Polybutadiene rubber 33 High Styrene rubber SS260 10 Zinc Oxide 2 Stearic Acid 1 Antioxidant 1 MC Sulphur 3.75 GPF Black 12 Wood flour 15 Expanded thermoset or thermoplastic resin 5 Rubber process oil 12 Recycled ball material 50 DPG 2.54 CBS 2.54

[0243] Test Ball Results:

TABLE-US-00018 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm)   56 g 0.350 52 6.6

[0244] This produces a ball that is out of specification in regards to the rebound and deformation. A series of amendments were carried out.

[0245] Corrective Actions [0246] a. Reduce oil to 4 pph [0247] b. Add keiselghur 20 pph [0248] c. Reverse ratio of natural rubber and polybutadiene rubber

TABLE-US-00019 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm)   58 g 0.275 55 6.59

[0249] Adjusted Formulation/Modified Mix

TABLE-US-00020 Natural rubber 33 Polybutadiene rubber 67 High Styrene rubber SS260 10 pph Zinc Oxide 2 Stearic Acid 1 Antioxidant 1 MC Sulphur 3.75 GPF Black 12 Wood flour 15 Expanded thermoset or thermoplastic resin 5 Rubber process oil 8 Recycled ball material 50 DPG 2.54 CBS 2.54 Keiselghur 20

EXAMPLE 2.3

[0250] Standard Formulation for Non-Pressurised Balls Plus Recycled Ball Material 30 PPH

TABLE-US-00021 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) TEST BALL 60/61 0.180 52 6.54

[0251] This produces a ball that is out of specification in regards to the deformation, rebound and weight. A series of amendments were carried out.

[0252] The Final Corrective actions taken: [0253] Corrective actions: [0254] a. Added 7 pph oil [0255] b. Changed ratio of Natural rubber and polybutadiene to 50/50 pph RHC

[0256] Adjusted formulation/modified mix

TABLE-US-00022 Natural rubber 50 Polybutadiene rubber 50 High Styrene rubber SS260 10 pph Zinc Oxide 2 Stearic Acid 1 Antioxidant 1 MC Sulphur 3.75 GPF Black 12 Wood flour 15 Expanded thermoset or thermoplastic resin 5 Rubber process oil 19 Recycled ball material 50 DPG 2.54 CBS 2.54

TABLE-US-00023 Weight Deformation Rebound Size ITF 56-59.4 g 0.220-0.291 53″ to 58″ 6.54-6.86 cm specification inches (135-147 cm) (2.57-2.70″) (0.56-0.74 cm) Test balls   57 g 0.275 54 6.62

[0257] This produces a ball that meets ITF ball standards.

[0258] Compression tests were carried out using a Stevens machine.

[0259] Further Example of a Pressurised Ball Mix [0260] SMR . . . 74 pph [0261] Zinc Oxide . . . 13 [0262] Stearic Acid . . . 1 [0263] DPG . . . 2 [0264] LMC . . . 42 [0265] Hard Clay . . . 21 [0266] Sulphur . . . 3.7 [0267] MBTS . . . 2 [0268] PEG(polyethylene gycol group) . . . 2 [0269] Poly butadiene . . . 1220 . . . 21 [0270] High Styrene Resin SS260 . . . 10 [0271] Calcium Carbonate . . . 10 [0272] Recycled tennis ball material . . . 50

[0273] Further example of a pressurised ball core formulation mix [0274] SMR 80 pph [0275] Polybutadiene 20 [0276] Zinc Oxide—12 [0277] Stearic Acid—1 [0278] Antioxidant—1 [0279] Clay—20 [0280] Calcium Carbonate—6 [0281] Light Magnesium Carbonate—40 [0282] MBTS—2 [0283] DPG—2 [0284] PEG—2 [0285] Sulphur 4 [0286] High Styrene Resin 10 [0287] Tennis ball recycled material 50 [0288] +/−10%

[0289] With or without recycled ball cover material in the tennis ball recycled material.

[0290] There are other possible ways of incorporating old tennis balls.

[0291] Balls for recycling may be granulated, mixed with a reclaiming ‘oil’, and subjected to heat.

[0292] Generally speaking any temperature over boiling point will work over a period of time but for economic reasons the higher the temperature the quicker reclaiming takes place.

[0293] One problem of using reclaimed material for tennis balls is that hardness and resilience of the reclaimed material is lower and recovering the correct ball parameters becomes more difficult.

[0294] Multi blending may be necessary to produce large uniform batches. It may not be a preferred way of incorporating recycled ball material because the greater use of energy and increased correction time involved.

[0295] FIG. 1 shows: [0296] 10 complete tennis ball formed according to the present invention [0297] 15 fabric cover [0298] 20 core half shell [0299] 30 core (complete)

[0300] Although illustrative embodiments of the invention have been disclosed in detail herein, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention.