NL1041623B1 - Improved field hockey ball for playing hockey on wet synthetic surfaces. - Google Patents

Abstract

This invention relates generally to field hockey balls, in particular to hockey balls for use on synthetic turf water sprayed wet pitches. The improved ball design will also lead to a better ball roll and play behavior during wet weather conditions on natural pitches and on non-water sprayed synthetic pitches. An embodiment of the invention is based on a dimpled type polyurethane matrix base material hockey ball design including a foam based center piece. In a hockey ball of the invention standard FIH dimensions (round ball with circumference of 230 mm) and weight (156 gram) are used to produce an injection molded polyurethane based hockey ball, however with addition, in the polyurethan mixture before the molding, of a very hydrophobic additive. Thus creating a hydrophobic or enhanced hydrophobic, even superhydrophobic, outermost layer surface on the hockey ball yet unknown in the prior art. Practice tests revealed a significant improvement in ball roll behavior on a wetted hockey field. Ball roll consistency also increased, although this improvement was not so much visible all ball rolls fell easily within the FIH standards for a Global field. A hockey ball is invented especially suitable for playing field hockey on a wet surface and is characterized in that the outermost layer is comprising a hydrophobic surface, more preferably a superhydrophobic surface and/or an enhanced hydrophobic surface.

Description

Title: Improved field hockey ball for playing hockey on wet synthetic surfaces.

Field of the invention:

This invention relates generally to field hockey balls, in particular to hockey balls for use on synthetic turf water sprayed wet pitches. The improved ball design will also lead to a better ball roll and play behavior during wet weather conditions on natural pitches and on non-water sprayed synthetic pitches.

Background of the invention:

In field hockey the Fédération Internationale de Hockey (FIH, www.fih.ch ) is the leading authority for regulating the hockey sport. In the FIH Handbook of performance requirements and test procedures for synthetic turf hockey pitches (May 2013 edition, 63 pages) a clear overview is given of approved turf products for playing hockey, of which in particular the water sprayed wetted turf at present form the top range of playing turfs.

All top level hockey matches such as Olympic games and world championships are at present played at water sprayed turfs. In The Netherlands already more than 1000 water pitches are in use and the number is still growing. These turf pitches are of course permeable for the water sprayed on it. FIH standard watering is specifying a 3mm average spraying with no collection dish, and/or a manufacturer recommended reduced watering amount which is usually much less as the FIH recommendation.

By wetting the pitch the players are better protected against for example burns in case of falling, it is mainly for safety reasons the water is sprayed on the pitch. A disadvantage is that the so called ball roll is negatively affected by the water layer, the water is braking and reducing the ball speed. In addition, a wet or slightly wet ball will be more slippery in ball stick contact leading to a less good ball control. On regular water sprayed turfs (also called full water pitch) no sand or whatever dirt will be present, only water is the problem. The hockey ball tends to swipe up a spray of water, it looks very similar to the effect you see when you bike during rain behind someone in front of you and the bike back tire is swiping up a water spray up backwards. The wiping up of water takes energy out of the ball and thus reduces ball speed.

In a hockey game the ball is usually played flat rolling over the pitch, of course the ball can be hit high on the goal and/or be flicked up (scooped) however in these situations the water on the pitch has no real negative effect on the ball behavior. It is not the flight behavior that inventor is trying to improve but essentially the ball roll over the wetted synthetic turf.

During the hockey game a ball cannot be cleaned and does not need so, dirt such as sand, leaves or grass is essentially not a real life problem as the water pitches are nowadays totally clean. A hockey ball stays clean, also because of the hard hits it gets every few seconds during a game. However, water braking up the ball roll is still quite a remaining problem, the game is slowed down.

Under the January 2012 FIH rules for Quality control of hockey balls, a maximum water absorption of 0,3 gram after completion of a absorption test is allowable. This low absorption rate does already indicate that for the current ball designs the real life water absorption for the materials in use is already very low (compared to the ball total weight of in between 156 and 163 grams, so 0,2 % max). However, a ball that would absorb no water at all is of course favorable.

As hockey is the only game played on an intentionally wetted synthetic turf with a ball rolling over the turf no other ball game and equipment can be taken as example from which to learn how to improve a hockey ball. With ball speeds of up to 180 km/hour rolling flat over the pitch the problem is only existing in hockey, for the specific combination of a hockey ball diameter and weight. Most hockey balls are completely smooth and at present perform just satisfactory on wet pitches, this present invention is improving the ball behavior especially during use and play on wetted pitches. Hockey ball behavior during free air flight is not an issue at all for the current hockey ball designs.

Current FIH rules stipulate the ball must be spherical, must have a circumference of between 224 and 235 mm, must weigh between 156 and 163 grams, can be made of any material and must be colored white (or use agreed colors contrasting with the playing field) and shall be hard with a smooth surface but indentations are permitted.

Further FIH requirements are added for surface characteristics, center of gravity, surface friction, rebound behavior, hardness, durability and shape retention. So all in all, the hockey ball design engineer is a specialized man skilled in the art and is quite limited in his possibilities for improvements. In hockey ball design, any improvement made is an inventive achievement on its own, there are hardly any known patents in the field of hockey balls.

Most hockey ball manufacturers such as Kookaburra, Gray Nicholls Sports, Dita, Rai, Hind, Apex etc. mainly sell hockey and cricket balls, other types of balls such as tennis balls, table tennis, bowls or other balls are very different in their technical requirements. Hockey balls sell in shops in the range of only 1 to 5 Euro, which essentially means for a plastic ball of say 160 grams that any improvement in used material and/or production method shall be cheap and easy to realize.

It is an object of this invention to improve hockey ball behavior such as a better rolling distance (less loss of velocity during rolling) and less ball roll deviation on a hockey pitch, in particular on a wetted surface pitch.

In the FIH may 2013 Handbook of Performance, Durability and Construction Requirements for synthetic Turf Hockey Pitches, par. 7.3, page 33, the better pitches for Global tournaments shall give a standardized ball roll test result of at least 10 meters with a ball roll consistency of less than 10 % of the overall mean value. This invention improves the ball roll length in this FIH test and the ball roll test consistency as well (as the test is carried out on a wetted surface). The handbook again underlines the importance of a longer ball roll and a consistent value for this factor, this is another reason to underline the importance of this invention. During the FIH test a standard ramp height of 1000 mm with a lower radius of 500 mm is used, the ball is rolled 5 times from this ramp to check for roll consistency.

As water on the pitch is in the real life situation not always equally present on all areas (except for the beginning of the game right after water spraying) on certain area's often drier spots show up during the game, even before half time. This is especially a problem in hotter climates such as Australia, South Africa, Spain, India, Pakistan, and the United States where also during hot sunny days hockey is played on water pitches, thus leading to quickly drying pitches with during a match a significant difference in local pitch wettability. Again, this invention has an improvement as over the known prior hockey balls, as in this unwanted but in real life practice often occurring situation the invention's ball behavior is more consistent both on the wet as well as on the dry/drier pitch parts.

Relevant known prior art documents are CN202654632U , CN104130370, AU2005202634 and GB2097319. CN202654632U describes a modified dimple pattern for a hollow hockey ball as compared to the official FIH Kookaburra dimpled type elite ball. These known Kookaburra dimpled balls are made of a coated Polyurethan (PU) casing housing a quilted center (the elite type), a Polyurethan foam center (the vision type) or a cork/rubber core (the standard type). The invention described below is applicable for any ball type, so including balls with a center as described above such as the Kookaburra PU dimpled balls, but also including any hollow balls.

Known prior art: Patent document AU2005202634 (Grays) describes a method how to produce such Polyurethan ball casings. CN104130370 describes an improved hockey ball matrix casing material with a good chemical stability, a 100:60 mixture of a polyether glycol and a polyester polyol is disclosed that does not need the stage of vulcanizing in a later process step, while also adding common ingredients such a chain extenders, linking agents, foaming stabilizers catalyzers, whipping agents and so on. PVC (PolyVinylChoride) is another used commonly material for hockey balls, usually the cheaper product ranges are using this material. GB2097319 discloses a more traditional hockey ball production method now seen as obsolete because the method is consuming too much time, with a traditional cork/rubber core. Another interesting relevant article is "The role of materials and construction on hockey ball performance (P88) by Dan Ranga, James Cornish and Martin Strangwood from the book "The engineering of Sport 7, pages 457 - 464 (Ed: Springer, DOI: 10.1007/978-2-287-99054-0_54 ).

Balls as described in GB2097319, AU2005202634, CN20265463U and CN104130370 and/or the known official FIH balls for international competition such as all the Kookaburra dimple elite series (and their other dimple vision and standard and seamless series as well) are all within the subject of this invention.

In the earlier days of hockey, before the 1980's, the dark colored cork balls often used to be coated with a white paint. After a while this coating, as any other coating on a hockey ball be it on cork/rubber or a plastic matrix material, was being hit off and damaged locally due the hard stick impacts and hitting on the metal goal posts, and the ball turned quickly again into a dark ball. It is therefor that nowadays no premium ball is coated with a thin layer (say less than 0,2 mm) because these layers get damaged quickly anyway. Any solution for this invention has to be extremely strong and resilient, preferably embedded in a suitable base matrix material such as Polyurethan (PU), PVC, or Polyether or polyester, or any mixture thereof. These are just mere examples of proposed base matrix hockey ball materials, many other possible materials can serve as a hockey ball base matrix material and this invention is not limited in any way to the examples mentioned here before.

Because at present no hockey ball manufacturer in the world has invented nor developed/marketed the proposed solution for this long standing water pitch problem (a more than 20 year old problem, which is also known since long as shows the special FIH approved dimpled water hockey ball solving a part of the problem) this invention has to be assessed on its own merits, and not be looked at with an easy going hindsight opinion. Most ingredients for the proposed solution are existing since many years however no one has ever thought of developing the proposed solution in order to solve the specific problem existing in hockey.

Summary of the invention:

It is an object of this invention to modify the outermost layer of a hockey ball to be hydrophobic, preferably to be more hydrophobic as the standard base matrix layer material such as polyurethan, or even more preferably to be superhydrophobic.

Another object of this invention is to provide methods for modifying the outermost layer of a hockey ball to be hydrophobic, or even better to be superhydrophobic.

The hydrophobic or superhydrophobic outermost layer repels water and leads to an improved ball roll (longer roll) with a more consistent standard value on wet pitches, according to standard FIH procedures. In practice, the improved hockey ball has a more consistent roll behavior both on completely wetted pitches as on less well (less equal) wetted pitches. As ball roll is longer and more consistent on wet pitches the hockey game will be played faster which is a favorable development for top hockey.

Applicant has performed fast video capturing on a wetted "Green Fields TX" hockey field surface (a FIH preferred turf product, used in the Hockey Men and Ladies World Championships in 2014) comparing the invention with prior art hockey balls.

The following basic observations were made on the differences in water spray development during ball roll on a wet surface: For a prior art dimpled hockey ball roll over a wetted surface, the water spray pattern is swiping upwards on the leeward side of the ball, this is typical for any of the known prior art hockey balls. A hockey ball according to this invention shows a quite different spray pattern as almost no water is lifted or swiped up at all. Much less water spraying is visible on the video capturing leading to a lower water induced drag and leading to an enhanced ball speed. Also for a corner drag flick the ball feel is better on the wet pitch, however only a specialist drag flicker will recognize this effect.

Detailed description of the invention: "Hockey Ball" as used herein is a ball especially intended to be used to play the game of hockey.

The international hockey federation FIH is at present guarding the specifications of hockey balls, however with the wording in this patent application and the claims in particular not only FIH hockey balls are covered but also any other ball suitable to play the game of field hockey. Current FIH rules stipulate the ball must be spherical, must have a circumference of between 224 and 235 mm, must weigh between 156 and 163 grams and can be made of any material suitable. Balls just not within this specification are also considered to be hockey balls, because national and/or local hockey organizations can issue broader or a bit less strict definitions of what is considered to be a 'hockey ball' according to the global FIH rules. "Contact angle", as used herein, refers to the angle at which a liquid/vapor water interface meets the solid hockey ball surface. It plays the role of a boundary condition and can be measured by a contact angle goniometer. "Hydrophobic", as used herein, refers to a hockey ball outmost layer having a contact angle of greater than 90 degrees. "Superhydrophobic", as used herein, refers to a hockey ball outermost layer having a contact angle of greater than 120 degrees. "Outermost layer", as used herein, is the layer or part of a hockey ball that is visible to the eye, that has for example contact with the playing field during the game. This outermost layer can also be a cover layer of any thickness on for example a 2-layer or multi layered hockey ball. "Matrix base material", as used herein, is the main material the outermost layer of the ball is made of, this is for the current hockey balls for example Polyurethane or PVC, or for example any of the materials specified in the relevant known prior art documents such as CN202654632U , CN104130370, AU2005202634 and GB2097319. CIM202654632U, this can also be any other suitable polymer of nonpolymer material. The matrix base is typically giving the ball the required shape, size, weight and hardness, in addition to that base material several other additives can be mixed into the matrix base material. "Nano particles", as used herein, are tiny nano or sub micron scale based particles. "Hydrophobic or superhydrophobic materials", as used herein, can be organic, inorganic or organometallic, suitable materials include but are not limited to silicone compounds, Teflon, silanes, mixtures of these afore mentioned materials, ptfe, combinations of any of these materials with nano particles, hdpe, technical waxes, fosfolipides and/or combinations thereof.

An embodiment of the invention is based on a dimpled type polyurethane matrix base material hockey ball design including a foam based center piece. In the hockey ball of the invention standard FIH dimensions (round ball with circumference of 230 mm) and weight (156 gram) are used to produce an injection molded polyurethane based hockey ball, however with addition, in the polyurethan mixture before the molding, of a very hydrophobic additive. Thus creating a hydrophobic or enhanced hydrophobic, even superhydrophobic, outermost layer surface on the hockey ball yet unknown in the prior art.

Several experimental hockey balls are produced with different sorts of additives, different amounts of additives (0,01%, 0,1 %, 1%, 2%, 5 % based on total weight), further using different types of additive grain sizes (from nano meter based sizes to sub micron) and different injection molding techniques and temperatures.

After producing these hockey balls a practice test has revealed a significant improvement in ball roll behavior on a wetted field hockey pitch (in this case: a 2015 Greenfields TX pitch). Ball roll for the 0,1 % additive did already grow from 10,4 m to 10,6 m, for the 1% and more amounts the ball roll grew an amazing 4 % on average (from 10,4 to 10,8 meter on average). Ball roll consistency also increased, although not so much visible all ball rolls fell easily within the FIH standard for a Global field. So there are clearly positive effects and the effects are measurable. A specific grain size effect could not really be significantly proven during the current reduced testing period, however there are certain test indications that for smaller grain sizes, in particular for nano particle size dimensions, a better hydrophobic effect is to be expected. Some tests were done with PTFE and PPFEMA very fine powders as hydrophobic additives (such as ptfe polytetrafuoroethylene micropowder homopolymer) added in the matrix base material before molding the hockey ball (reference is further made to US patent applications 20080015298 and US20070237947 which are incorporated herein by reference).

For strength and stress reasons, and because of compound chemical stability reasons, only a limited amount of hydrophobic additives can be added into the polymer base material, but by reducing a bit in the standard amounts of other common ingredients such as chain extenders, linking agents, foaming stabilizers catalyzers and whipping agents a strongly improved mixture especially for the production of hockey balls can easily be proposed. Also a 2-layer or multi-layered approach would be feasible in which only in the most outermost layer the higher cost hydrophobic additives would be present. It is from the present test results clear that an enhanced hockey outermost layer wettability, i.e. with enhanced hydrophobic properties as compared to the standard basic matrix material, improves ball roll and also ball roll consistency considerably. A known wettability improving product already on the market such as "Ultra-ever dry", which makes the ball polymer matrix material attracting oxygen and thus making the outer surface more hydrophobic can also be used for preparing a hockey ball according to this invention. By treating a standard PU dimpled hockey ball afterwards with "ultra-ever dry" already a major improvement can be achieved, however for a more durable and wear resisting result it is preferable and better to include the hydrophobic effect enhancing additive(s) already during the molding stage of the hockey ball.

For a ball matrix material such as Polyurethan (PU) adding a hydrophobic additive such as a fosfolipide would be feasible, for the man skilled in the art (a chemist specialized in polymers) many other possibilities exist in order to enhance the hydrophobicity of the ball matrix material. Another possible approach is to create an additional micropattern nano roughness surface on the ball outermost surface, and/or to include hydrophobic or superhydrophobic nanoparticles in the outer layer matrix material. As developments go swift in the field of nano particle development not only present but also future, yet to be developed, nano particles enhancing surface hydrofobicity and improving the wettability factor are included in the scope of protection of the claims. A hockey ball according to this invention could be named for example a "nano water (hockey) ball", "dimpled nano hockey ball", "improved hockey water ball", "dimple plus hockey ball", "PU nano (hockey) ball", "dimpled nano water ball", "elite water ball", "elite nano ball", "Elite Lotus ball", and so on, in order to distinguish from the common prior art hockey balls.

For the sake of a better understanding of this invention for non dutch speakers the following clauses are included in English: 1/ Hockey ball especially suitable for playing field hockey on a wet surface, characterized in that the outermost layer is comprising a hydrophobic surface, more preferably a superhydrophobic surface and/or an enhanced hydrophobic surface. 2/ Hockey ball according to claim 1, further characterized in that it comprises outer surface indentations, such as dimples or a dimple pattern. 3/ Hockey ball according any of the preceeding claims, further characterized in that the ball is spherical, has a circumference of between 220 mm and 250 mm, and weighs between 120 and 170 grams. 4/ Hockey ball according to any of the preceeding claims, further characterized in that the ball is made of a polymer matrix base material or a polymer mixture matrix base material, such as for example a Polyurethan, Polyvinylchloride, Polyester, Polystryrene, Polyethylene, Polypropylene and/or any mixtures thereof. 5/ Hockey ball according to any of the preceeding claims, further characterized in that the outermost layer surface has enhanced hydrophobic or superhydrophobic properties as compared to the ball polymer or polymer mixture matrix base material. 6/ Hockey ball according to any of the preceeding claims, further characterized by having a strong water repellant outer surface. 7/ Hockey ball according to any of the preceeding claims, further characterized by having a two-layer or multi-layer structure, wherein in the most outer layer enhanced hydrophobic or superhydrophobic properties, as compared to the polymer or polymer mixture matrix base material from which the ball is basically made of, are present. 8/ Hockey ball according to any of the preceeding claims, further characterized in that additives such as hydrophobic nanoparticles are incorporated in the outermost layer of the hockey ball and/or the additives are colored in the same color as the ball base matrix material. 9/ Hockey ball according to any of the preceeding claims, further characterized in having an improved wet surface FIH test ball roll length and ball roll consistency performance, as compared to prior art hockey balls. 10/ Hockey ball according to any of the preceeding claims, further characterized in that the outermost surface is essentially flat and smooth, so does not comprise dimples or other indents in or on the surface. 11/ Method for producing a hockey ball especially suitable for playing field hockey on a wet surface, characterized in preparing a ball with an outermost layer with a hydrophobic surface, more specific a superhydrophobic surface or an enhanced hydrophobic surface. 12/ Method for producing a hockey ball according to claim 11, further characterized in that during ball production outer surface indentations such as a dimple pattern is created in the outermost layer surface. 13/ Method for producing a hockey ball according to claim 11 or 12 or a combination thereof, further characterized in that the ball is produced of a polymer or polymer mixture based matrix base material such as Polyuretan, Polyvinylchloride, Polyester, Polystryrene, Polyethylene, Polypropylene and/or mixtures thereof combined with 0,01 % to 5 % on a total weight base hydrophobic or superhydrophobic additives such as sub micron particle PTFE teflon, and/or nano scale size base particles including silicone compounds, or silane based particles, or fosfolipide based particles and/or mixtures thereof. 14/ Method for producing a hockey ball according to any or more of the previous claims 11,12 and/or 13, further characterized in that one of the steps of producing the ball is a step of injection molding of a mixture of the polymer or polymer mixture based material and the hydrophobic or superhydrophobic additives. 15/ Use of a hockey ball according to any of the previous claims 1 -10, and/or use of a hockey ball produced according to any of the previous claims 11-14.

In the following claims (conclusies) and in the preceding description of the invention, except where the context required otherwise due to express language of necessary implication, the word "comprise" or variations such "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

This invention is susceptible to variations in its practice. For example basic compositions may be used to create a variety of materials therefor it is not intended that this invention be limited by the specific exemplifications set forth hereinabove. Rather, what is intended to be covered hereby is all subject matter within the scope of the appended claims, including the full range of equivalents to which such claims may be entitled as a matter of law.

Claims (15)

Hockey ball particularly suitable for playing hockey on a wet field, characterized by an outer layer comprising a hydrophobic surface, more in particular a superhydrophobic surface and / or a reinforced hydrophobic surface. Hockey ball according to one of the preceding claims, further characterized by an outer surface provided with indentations, such as, for example, dimples or a dimple pattern. Hockey ball according to any one of the preceding claims, further characterized in that the ball is round, has a circumference of between 220 mm and 250 mm, and has a weight of between 120 grams and 170 grams. Hockey ball according to any one of the preceding claims, further characterized in that the ball is made of a polymer matrix base material or a polymer mixed matrix base material, such as, for example, polyurethane, polyvinyl chloride, polyester, polystyrene, polyethylene, polypropylene and / or mixtures thereof. A hockey ball according to any one of the preceding claims, further characterized in that the surface of the outer layer has enhanced hydrophobic or superhydrophobic properties in comparison with the polymer or polymer mixture comprising the ball matrix base material. A hockey ball according to any one of the preceding claims, further characterized by an outer layer surface with strong water-repellent properties. A hockey ball according to any one of the preceding claims, further characterized by a two-layer or multi-layer structure, wherein the outer layer has enhanced hydrophobic or superhydrophobic properties compared to the polymer or polymer blend matrix material of which the ball is essentially made. Hockey ball according to any one of the preceding claims, further characterized by hydrophobic nanoparticles added to the outer layer of the ball and / or in that additives in the outer layer have a color similar to the basic matrix material. Hockey ball according to any one of the preceding claims, further characterized by a roll length and roll consistency improved compared to the balls known to date during an FIH ball test on a wet field. Hockey ball according to any one of the preceding claims, further characterized by an outer layer surface that is essentially flat and smooth, i.e. without dimples or indentations in or on the surface. 11 - Method for producing a hockey ball, in particular a hockey ball more suitable for playing hockey on a wet field, characterized by an outer layer with a hydrophobic surface, more in particular a superhydrophobic surface and / or a reinforced hydrophobic surface. A method of producing a hockey ball according to claim 11, characterized by creating dimples such as a dimpled pattern in the surface of the outer layer during production. Method for producing a hockey ball according to claim 11 or 12 or a combination thereof, further characterized by a base matrix material consisting of a polymer or a polymer mixture such as polyurethane, polyvinyl chloride, polyester, polystyrene, polyethylene, polypropylene and / or mixtures thereof, further combined / mixed with 0.01% to 5% by weight of hydrophobic or superhydrophobic additives, such as, for example, PTFE Teflon sub-micron particles, nano-particle-containing silicone mixtures, silane-based particles, phospholipid-based particles and / or mixtures thereof. Method for producing a hockey ball according to one or more of the preceding claims 11, 12 and / or 13, further characterized in that one of the steps in the production process is an injection molding step with a mixture of the polymer or polymer mixture and the hydrophobic or superhydrophobic additives. - Use of a hockey ball according to one of claims 1 to 10, and / or use of a hockey ball produced according to one of claims 11 to 14.