A Laminated Carboxylated Acrylonitrile Butadiene Latex Seamless Bladder and a process for manufacturing thereof."

Field of the Invention: -

The present invention relates to a laminated carboxylated acrylonitrile butadiene latex seamless bladder and a process for manufacturing thereof.

Particularly, it relates to a laminated carboxylated acrylonitrile butadiene latex seamless bladder which is suitable for hand stitched inflatable balls and a process for manufacturing thereof.

More particularly, it relates to a laminated carboxylated acrylonitrile butadiene latex seamless bladder which is suitable for machine stitched inflatable balls and a process for manufacturing thereof. Background of the Invention: -

A bladder is an independently saleable commodity. If it is employed in medical applications for gas transfusion etc., it can be employed without any outer cover thereon. However, if it is employed in sport industry for manufacture of balls, particularly for, inflatable balls, then it is covered with an outer cover to protect it from bursting and to form a ball. The outer cover is either hand stitched or machine stitched depending upon the game in which it is being used or the desired characteristics and quality of the end product. The hand stitched outer cover is required, for example, in match and practice balls, and machine stitched cover is required, for example, in match and practice balls including promotional balls wherein the volume of demand is relatively higher. The term promotional balls means the balls used by manufacturers and/or promoters to promote their products and events, such as during trade fairs, national games, international games, etc. The physical characteristics of bladder for both types of outer covers are different.

The present invention particularly relates to a laminated carboxylated acrylonitrile butadiene latex seamless bladder, which is suitable for hand stitched inflatable balls.

In one embodiment, the scope of present invention also includes a laminated carboxylated acrylonitrile butadiene latex seamless bladder, which is suitable for machine stitched inflatable balls, because the present bladder has also been found suitable for machine stitched balls including, but not limited to inflatable balls, and also for medical applications including gas transfusion.

For inflatable balls, the film for manufacturing a bladder is not only required to be of suitable weight, but is also required to have controlled inflation capability when inflated as a bladder, to give required shape and size of the ball and to protect the bladder made from such film as well as the outer cover from de-shaping and bursting on inflation.

On the contrary, for medical applications, such as for manufacturing hand gloves, the film for manufacturing the gloves is neither required to be of a suitable weight nor required to have controlled inflation capability as it is neither required to have bounce characteristics nor to be inflated as a bladder to have a particular shape and size, and hence, nor it is required to be protected from de-shaping and bursting on inflation.

It has been observed that for manufacturing a hand glove, even a very lighter film having weight varying from about 100 to about 200 mg/inch ² is sufficient because, as stated, it is neither required to have any bounce characteristics nor to have a shape as in case of a ball. Further, the glove is not required to be stitched to any outer cover.

On the contrary, it has been observed that for hand stitched inflatable balls, the film for manufacturing a bladder is required to have relatively very heavy weight varying from about 500 to about 700 mg/inch ² , which has been found suitable for providing the shape and bounce characteristics to the hand stitched balls, because the outer cover of the ball and its stitches are strong enough.

Similarly, for machine stitched inflatable balls, it has been observed that the film for manufacturing a bladder is required to have even further heavier weight varying from about 700 mg/inch ² to about 1.5 g/inch ² , which has been found suitable for providing the shape and bounce characteristics to the machine stitched balls, because the outer cover of such balls and its stitches are not strong enough as compared to hand stitched balls.

Therefore, a film used for manufacturing a hand glove cannot be employed for manufacturing a bladder suitable for a ball.

It has been further observed that in conventional balls, if bladder is not made of a film having a required weight and controlled inflation capability, the required weight and controlled inflation capability is, then, generally achieved by applying one or more layers of thread breading around the outer layer of the bladder, which has been found to result in increase in the hardness of the bladder, and hence, the bladder does not remain suitable for playing football, and additionally it looses its spherical shape.

In conventionally available inflatable balls, the bladder made from butyl rubber is used. However, such bladders are not of required weight. In case of butyl rubber bladders, the required weight is achieved by increasing its wall thickness which is

determined based on the weight required by employing conventionally known moulding process which is conventionally carried out on an unsupported film made by pasting four panels and not on a bladder per se.

The major problem of manufacturing a butyl rubber bladder having required weight by increasing its wall thickness by employing conventionally known moulding is that the cost of material increases manifold.

Further, the major problem of the conventionally known moulding process is that it cannot be employed if a seamless bladder is required. The present invention particularly aims of providing a laminated seamless bladder, therefore, the conventionally known moulding process, is not suitable at all.

Still further problem of employing conventionally known moulding process is that even the joints are not of uniform weight, that is, weight at the joints of the bladder is relatively higher adversely resulting in wobbling effect during flight of the ball.

Yet another problem of employing conventionally known moulding process is that it has been found to be more expensive, and yet resulting in higher rejection, and hence, effectively lower production rate with higher capital cost.

Further, it has been observed that even by manufacturing the butyl rubber bladder by employing conventionally known moulding process, the required weight cannot be achieved. Therefore, in case of conventionally available bladders thread breading of nylon fiber around butyl bladder is applied to achieve the desired weight characteristics, which has been found to enhance controlled inflation capability of the bladder produced, but as. stated herein, the thread breading results in increase in the hardness of the bladder, and hence, makes it unsuitable for playing football, and additionally loss of its spherical shape.

In US Patent No. 4,191,375, issued on March 4, 1980, a game ball having an inner bladder provided with a layer of yarn fiber is discussed.

The US Patent No. 4,830,373, issued to Dehnert et al, describes a soccer ball which includes an inflatable floating bladder comprising two ply of butyl within a thread form of carcass.

The US Patent Nos. 5,772,545 and 6,390,941 Bl issued to Ou describe use of strengthened nylon thread over lapping each other to form a web like layer which permanently embraces and adheres to the bladder and supports the outer cover of the ball.

The US Patent No. 6,793,597 describes machine stitched ball with floating bladder. It consists of bladder and the outer cover wherein the outer cover is vulcanized with web

of thread and adhesive. Further, the outer surface of the bladder is coated with the silicone releasing chemical before winding.

However, it has been observed that the fiber is applied around outer layer of the bladder in the form of a web like structure which does not allow bladder to inflate more than it has initially inflated for the purpose of breading by nylon fiber. Therefore, such bladders suffer from problem of limited inflation.

Further, as stated herein, it has been observed that due to thread breading, the bladder becomes harder, which limits its applications and wide acceptability because harder the bladders hit the players harder during playing, for example, while kicking, heading etc. This problem can be overcome, but by providing additional padding between thread breading of the bladder and outer cover of the ball, which in-tum adds on the cost of the end product - ball, and hence make commercially unviable.

Further, when a bladder is used in sports industry, it is desired that it should have judicious combination of bounce as well as air retention characteristics without sacrificing one property for the another property.

It has been observed that bladders made from synthetic butyl rubber exhibit good air retention characteristics, but have poor bounce characteristics. Such bladders have been accepted, but the need for laminated seamless bladder having judicious combination of good air retention characteristics and good bounce characteristics and controlled inflation characteristics, and still having low manufacturing cost, high productivity and low rejection rate has not been satisfied.

Further, the bladders made from natural rubber exhibit good bounce characteristics, but have poor air retention characteristics. Such bladders have also been accepted, but the need for laminated seamless bladder having judicious combination of good air retention characteristics and good bounce characteristics, and controlled inflation characteristics, and still having high productivity and low rejection rate has not been satisfied.

It has been observed that even the bladders made from conventionally used synthetic latex exhibit good air retention characteristics, but have poor bounce characteristics and poor controlled inflation characteristics.

Further, it has been observed by the inventors of the present invention that when a bladder is made from synthetic latex, particularly from synthetic acrylonitrile butadiene latex, the processability of the synthetic latex to have a film of desired thickness and weight, which can suitably has judicious combination of good air retention characteristics

and good bounce characteristics, and controlled inflation characteristics has not been possible.

It has been found that bladders made from synthetic acrylonitrile butadiene latex film are of thickness varying upto about 0.20 mm. The main drawback of a film of synthetic acrylonitrile butadiene latex having such a lower thickness is that stripping of film becomes very difficult.

Further, the inventors of the present invention have found that if a film of synthetic acrylonitrile butadiene latex for manufacture of a bladder having thickness more than about 0.25 mm is achieved, then drying problem is observed during manufacture of a film which in-tum has been found to cause cracks in the film.

It has been further found that bladders made from synthetic acrylonitrile butadiene latex film are of weight varying upto about 300 mg/inch ² , which as described herein, have not been found suitable for providing the shape and bounce characteristics even of the hand stitched balls, because as described herein, a film to manufacture a bladder suitable for hand stitched inflatable balls should have relatively very heavy weight varying from about 500 to about 700 mg/inch ² and for machine stitched inflatable balls should have even further heavier weight varying from about 700 mg/inch ² to about 1.5 g/inch ² .

Still another problem observed with synthetic acrylonitrile butadiene latex is that it results in a film having modulus varying from about 10 to 12 Kg/Cm ² at 100% stretch [or elongation], which has been found to be a main cause of resulting in a bladder having poor bounce characteristics.

Yet another problem observed with synthetic acrylonitrile butadiene latex is that it results in a film having poor cross-linking as found by measuring tensile strength which has been found to be varying from 60 to 70 kg/cm ² and elongation at break which has been found to be varying from 450 to 500%. Such a poor cross-linking has been found to be another cause of resulting in a bladder having poor bounce characteristics as well as reduced air retention characteristics.

Even further it has been observed that bladder made from film of synthetic acrylonitrile butadiene latex gets tear-off from its neck during stripping from a mould resulting in total loss of production.

Further, such bladders made from conventionally used synthetic latex do not have required bounce and controlled inflation characteristics. Therefore, such bladders have not been commercially acceptable.

Therefore, it can be concluded that the conventionally used synthetic latex, particularly the synthetic acrylonitrile butadiene latex is not suitable for manufacturing a film suitable for manufacturing a bladder for inflatable balls.

Further, the bladders made from natural latex exhibit good bounce characteristics, but have poor air retention characteristics. Such bladders have been accepted, but the need for a bladder having judicious combination of good air retention characteristics and good bounce characteristics, and controlled inflation characteristics, and still having low manufacturing cost, high productivity and low rejection rate has not been satisfied.

Accordingly, it has been found that when conventionally available bladders are made either from conventionally used synthetic rubber or synthetic latex, or from conventionally used natural rubber or natural latex, these have either poor air retention characteristics or poor bounce characteristics, or poor controlled inflation characteristics. Therefore, neither the bladders made from conventionally used synthetic rubber or synthetic latex, nor the bladders made from conventionally used natural rubber ?or natural latex have been commercially acceptable.

Therefore, a need to have a bladder having judicious combination of bounce characteristics as well as air retention characteristics as well as controlled inflation capability without sacrificing one property for the another property has been felt for an inflatable ball.

An attempt has been made to manufacture bladders by employing blends of natural rubber and synthetic rubber.

However, it has been found that even bladders made from blends of natural rubber and synthetic rubber suffer primarily from poor curing, i.e. cross linking, which in-turn results in low bounce characteristics. Even blends of synthetic rubber with natural rubber have not been able to result in a bladder having good bounce as well as good air retention characteristics.

Another problem of bladders made from blends of natural rubber and synthetic rubber is that these are not seamless as these are made by employing conventionally known moulding process, and hence, do not have uniform weight over the entire area, which in-turn results in an inflatable ball having wobbling effects, and therefore, higher rejection rate of the bladders and balls made therefrom.

Still another attempt has been made to manufacture bladders by employing blends of natural latex and synthetic latex, wherein such bladders are manufactured by employing dipping process, and wherein synthetic latex is selected from a group consisting of synthetic acrylonitrile butadiene latex, neoprene {for example

polychloroprene latex], isoprene [for example, polylsoprene latex], SBR [styrene butadiene rubber] and natural latex is commonly known as centrifuged latex.

However, it has been found that even bladders made from blends of natural latex and synthetic latex suffer primarily from poor curing, i.e. cross linking, which in-turn results in low bounce characteristics. Even blends of synthetic latex with natural latex have not been able to result in a bladder having good bounce as well as good air retention characteristics and controlled inflation characteristics.

Accordingly, it has been found that when conventionally available bladders are made either from blends of natural rubber and synthetic rubber or from blends of natural latex and synthetic latex, these have poor curing, and hence, have poor bounce characteristics, and in-addition bladders made from blends of natural rubber and synthetic rubber are not seamless bladders. Therefore, neither the bladders made from natural rubber and synthetic rubber nor the bladders made from natural latex and synthetic latex got commercial acceptance, because these bladders also lack judicious combination of good air retention characteristics, good bounce characteristics and controlled inflation characteristics.

Yet another attempt has been made to manufacture bladders by employing laminates of natural latex and synthetic latex, wherein synthetic latex is selected from a group consisting of synthetic acrylonitrile butadiene latex, neoprene [for example polychloroprene latex], isoprene [for example, polylsoprene latex], SBR [styrene butadiene rubber] and natural latex is commonly known as centrifuged latex.

However, it has been found that even bladders made from laminates of natural latex and synthetic latex primarily suffer not only from poor curing, i.e. cross linking, which in-turn results in low bounce characteristics, but also from problem of delamination of layers of the conventional laminate, which in-turn results in bursting during performance, and hence, further rejection of the bladder. Accordingly, even conventionally known laminates of natural latex and synthetic latex have not been able to result in a bladder having good bounce as well as good air retention characteristics and controlled inflation characteristics, and good strength of the laminate per se to result in strong enough bladder.

Therefore, it has been found that even the bladders made from conventionally available laminates of natural latex and synthetic latex have not been commercially acceptable.

Even another attempt to manufacture bladders by employing laminates of natural rubber and synthetic rubber has not been commercially successful.

It has been found that even bladders made from conventionally available laminates of natural rubber and synthetic rubber primarily suffer not only from poor curing, i.e. cross Unking, which in-turn results in low bounce characteristics, but also from problem of delamination of layers of the conventional laminate, which in-turn results in bursting during performance, and further rejection of the bladder. Accordingly, even conventionally available laminates of natural rubber and synthetic rubber have not been able to result in a bladder having good bounce as well as good air retention characteristics and controlled inflation characteristics, and good strength of the laminate per se to result in strong enough bladder. Need of the Invention: -

Therefore, there is a need to have a laminated seamless bladder and a process for manufacturing thereof, wherein the bladder has judicious combination of good air retention characteristics as well as good bounce characteristics as well as controlled inflation characteristics without sacrificing one property for the another property, and the process for manufacturing thereof has low manufacturing cost, high productivity and low rejection rate, and the bladder is suitable for hand stitched as well as machine stitched inflatable balls. Objects of the Inventiσn:-

Accordingly, main object of the present invention is to provide a laminated seamless bladder and a process for manufacturing thereof, wherein the bladder has judicious combination of good air retention characteristics as well as good bounce characteristics as well as controlled inflation characteristics without sacrificing one property for the another property, and the process for manufacturing thereof has low manufacturing cost, high productivity and low rejection rate, and the bladder is suitable for hand stitched as well as machine stitched inflatable balls.

This is also an object of the present invention to provide a laminated seamless bladder which is made from a synthetic latex, which is particularly selected from carboxylated acrylonitrile butadiene latex or its blend, which is laminated with rubber, and the latex is selected from a group consisting of synthetic styrene butadiene latex, neoprene, heat resistant natural rubber latex.

Another object of the present invention is to provide a laminated seamless bladder, which is capable of protecting its outer cover from bursting whether it is hand stitched or machine stitched, and hence, has wider acceptability and applicability.

Still another object of the present invention is to provide a laminated seamless bladder, which not only has required and suitable weight, but also has further enhanced

controlled inflation characteristics, and hence, is capable of giving required shape and size of the ball and protecting the outer cover from de-shaping and bursting on inflation.

Yet another object of the present invention is to provide a laminated seamless bladder, wherein its film has weight varying from about 700 mg/inch ² to about 1.5 g/inch ² , and hence, is suitable not only for providing the shape and bounce characteristics to a hand stitched ball, but also to a machine stitched ball.

This is also an object of the present invention to provide a laminated seamless bladder, wherein its required weight and further enhanced controlled inflation capability is achieved without applying layers of thread breading around its outer layer, and hence, it has reduced hardness, and therefore, it does not require additional padding, and still has wider applications and wider acceptability, because it does remain suitable for playing football, and additionally it does not loose its spherical shape.

This is also an object of the present invention to provide a laminated seamless bladder, wherein further enhanced controlled inflation capability is not achieved by applying layers of thread breading around its outer layer in the form of a web like structure or otherwise, and hence, it does not suffer from problem of limited inflation.

This is also an object of the present invention to provide a laminated seamless bladder, wherein required weight is achieved by increasing its wall thickness, which is determined based on the weight required, by pasting the compounded rubber sheet on the outer surface of the bladder shell, and not by conventionally known moulding process, and hence, it is capable of overcoming drawbacks of a conventionally known moulding process, which as described herein is conventionally carried out on an unsupported film made by pasting four panels and not on a bladder per se.

Accordingly, this is also an object of the present invention to provide a laminated seamless bladder, wherein it is manufactured by a process which is capable of resulting in a laminated seamless bladder having no joints, and hence, having uniform weight, and therefore, having no wobbling effect during flight of the ball, and still with no substantial increase in cost of material and process per se, and still having increased production rate with substantially reduced capital cost and rejection rate.

This is also an object of the present invention to provide a laminated seamless bladder, which is manufactured by a process which is not only capable of resulting in a laminated seamless bladder, but is also capable of resulting in a bladder made of film having desired thickness varying from about 0.70 mm to 3.0 mm, and weight varying from about 700 mg/inch ² to about 1.5 g/inch ² without any problem of processability, and

hence, having no stripping problem and no drying problem, and therefore, having no cracks in the film.

This is also an object of the present invention to provide a laminated seamless bladder having modulus varying from about 60 to 80 Kg/Cm ² at 100% stretch [or elongation], which has been found to be a main cause of resulting in a bladder having good bounce characteristics and controlled inflation.

This is also an object of the present invention to provide a laminated seamless bladder having good tensile strength varying from about 120 to 150 kg/cm ² and elongation at break varying upto about 450%, and hence, good cross-linking, and therefore, having good bounce characteristics as well as good air retention characteristics and as well further enhanced controlled inflation characteristics.

This is also an object of the present invention to provide a laminated seamless bladder which does not get tear-off from its neck during stripping from a mould, and hence, does not result in loss of production.

This is also an object of the present invention to provide a laminated seamless bladder which is made from a single laminated film, and still does not suffer from problem of delamination of layers, and therefore, no problem of bursting during performance and further rejection thereof.

Other objects and advantages of the present invention will become more apparent from the following description when read in conjunction with the accompanying examples which are not intended to limit scope of the present invention. It may be noted that the accompanying examples are only for the illustration purpose. Description of the Invention: -

Accordingly, the present invention relates to a laminated seamless bladder, which has not only a judicious combination of good air retention characteristics as well as good bounce characteristics, but also the further enhanced controlled inflation characteristics, that's too without sacrificing one property for the another property, and being suitable for hand stitched as well as machine stitched inflatable balls, wherein the bladder is made from a synthetic latex, particularly from carboxylated acrylonitrile butadiene latex or its blend and no other latex, which is laminated with a rubber.

Accordingly, the present invention also relates to a process for manufacturing a laminated seamless bladder from a synthetic latex, particularly from carboxylated acrylonitrile butadiene latex or its blend which is laminated with rubber, wherein the bladder has a judicious combination not only of good air retention characteristics and good bounce characteristics, but also has been found to have further enhanced controlled

inflation characteristics, that's too without sacrificing one property for the another property, and still being suitable for hand stitched as well as machine stitched inflatable balls, and wherein the process also has low manufacturing cost, high productivity and low rejection rate.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its belnd, which is capable of protecting its outer cover of the ball from bursting whether it is hand stitched or machine stitched, and hence, has wider acceptability and applicability.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having required and suitable weight and further enhanced controlled inflation, and hence, being capable of giving required shape and size of the ball and protecting the outer cover from de-shaping and bursting on inflation.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having weight varying from about 700 mg/inch ² to about 1.5 g/inch ² , and hence, being suitable not only for providing the shape and bounce characteristics and further enhanced controlled inflation to a hand stitched ball, but also to a machine stitched ball.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend, wherein its required weight and further enhanced controlled inflation capability is achieved without applying layers of thread breading around its outer layer, and hence, having reduced hardness, and therefore, not requiring additional padding, and still having wider applications and wider acceptability, and still being suitable for playing football, and additionally not loosing its spherical shape.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend, wherein further enhanced controlled inflation capability is not achieved by applying layers of thread breading around its outer layer in the form of a web like structure or otherwise, and hence, it does not suffer from problem of limited inflation.

In accordance with one of the embodiments, the present invention relates to a laminated seamless baldder of carboxylated acrylonitrile butadiene latex or its blend, wherein required weight is achieved by increasing its wall thickness, which is determined based on the weight required, by pasting the compounded rubber sheet on the outer surface of the bladder shell, and not by conventionally known moulding process, and

hence, being capable of overcoming drawbacks of a conventionally known moulding process, which is conventionally carried out on an unsupported film made by pasting four panels and not on a bladder per se.

In accordance with one of the embodiments, the present invention relates to a laminated seamless baldder of carboxylated acrylonitrile butadiene latex or its blend having no joints, and hence, having uniform weight, and therefore, having no wobbling effect during flight of the ball.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having thickness varying from about 0.70 mm to 3.0 mm and weight varying from about 700 mg/inch ² to about 1.5 g/inch ² .

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having no stripping problem and no drying problem, and therefore, having no cracks therein.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having modulus varying from about 60 to 80 Kg/ Cm ² at 100% stretch [or elongation], and hence, having good bounce characteristics.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend having good tensile strength varying from about 120 to 150 kg/cm ² and elongation at break varying upto about 450%, and hence, having good cross-linking, and therefore, not only having good bounce characteristics and good air retention characteristics, but also having further enhanced controlled inflation characteristics.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend which does not get tear-off from its neck during stripping from a mould.

In accordance with one of the embodiments, the present invention relates to a laminated seamless bladder of carboxylated acrylonitrile butadiene latex or its blend which is made from a single film, and still does not suffer from problem of delamination of layers, and therefore, no problem of bursting during performance.

In accordance with one of the preferred embodiments, the present invention also relates to a bladder:

wherein the bladder comprises carboxylated acrylonitrile butadiene latex or its blend with one or more latex which is laminated with rubber, wherein lamination is performed by pasting without thread breading; wherein the bladder has modulus varying from about 60 to 80 Kg/Cm ² at 100% stretch [or elongation]; good tensile strength varying from about 120 to 150 kg/cm ² ; elongation at break varying upto about 450%; and thickness varying from about 0.70 mm to 3.0 mm confirming its good cross-linking and not only good bounce characteristics and good air retention characteristics, but also further enhanced controlled inflation characteristics without sacrificing one property for the another property; wherein the bladder has weight varying from about 700 mg/inch ² to about 1.5 g/inch ² and still has further enhanced controlled inflation, wherein its required weight and further enhanced controlled inflation capability is achieved without applying layers of thread breading around its outer layer confirming its reduced hardness even without requiring additional padding, and hence, having no problem of limited inflation; wherein the bladder has uniform weight and no joints, respectively, confirming its no wobbling effect during flight of the ball and seamless nature, and additionally no lose of its spherical shape; wherein the bladder is capable of providing required shape and size of the ball and protecting the outer cover from de-shaping and bursting on inflation whether the balls is hand stitched or machine stitched, and hence, having wider acceptability and applicability.

In accordance with one of the preferred embodiments, the latex for blending the carboxylated acrylonitrile butadiene latex is selected from a group comprising Neoprene

Latex, heat resistant grade Natural Latex, styrene-butadiene rubber latex, or mixture thereof.

In accordance with one of the preferred embodiments, rubber for lamination of carboxylated acrylonitrile butadiene latex or its blend is selected from a group comprising synthetic rubber, natural rubber or mixture thereof.

In accordance with one of the preferred embodiments, the synthetic rubber is selected from a group comprising styrene-butadiene rubber [SBR], acrylonitrile butadiene rubber [NBR], neoprene rubber [CR], polybutadiene rubber [PBR], butyl rubber [HR],

EPDM rubber, reclaim rubber, polyurethane [PU] rubber.

In accordance with one of the preferred embodiments, the natural rubber is selected from conventionally available natural rubber.

It has been observed that if carboxylated acrylonitrile butadiene latex is employed after blending with one or more of above-defined materials, it results in advantages of better adhesion compatibility with lamination which as described herein has additional advantage of further enhancing the controlled inflation characteristics.

It has also been observed that blended latex of present invention demonstrates further enhanced heat resistant properly of the bladder to be used for improved moulding process of present invention, which has additional advantage of avoiding degradation.

Another advantage of employing blended latex of present invention is that same processing and vulcanizing systems can be used.

In accordance with one embodiment of the present invention, the carboxylated acrylonitrile butadiene latex is characterized by:- acrylonitrile copolymer with medium or high acrylonitrile level varying from about

26% to about 39%; solid content varying from about 39% to about 50% of dry rubber contents; pH value varying from about 7.5 to about 8.5; viscosity varying from about 14 to about 65 mPas; surface tension varying from about 30 to about 40 mN/m.

In accordance with one of the embodiments, the present invention relates to a bladder, wherein the bladder is preferably made from a single film of carboxylated acrylonitrile butadiene latex, which is preferably laminated with a layer of rubber, but surprisingly it does not suffer from problem of delamination of layers, and therefore, no problem of bursting during performance. The required enhanced controlled inflation cannot be obtained with dipping process per se. If the single film of carboxylated acrylonitrile butadiene latex or its blend is laminated with above-defined material, the bladder demonstrates further enhanced controlled inflation characteristics.

In accordance with one of the preferred embodiments of present invention, it relates to a bladder, wherein required weight of the bladder is achieved by increasing its wall thickness, which is determined based on the weight required, by pasting the compounded rubber sheet on the outer surface of the bladder shell, and not by employing conventionally known moulding process, and hence, the bladder is capable of overcoming drawbacks of a conventionally known moulding process, which is conventionally carried out on an unsupported film made by pasting four panels and not on a bladder per se.

In accordance with another embodiment of the present invention, it relates to a process for manufacturing of a laminated seamless bladder, wherein it does not get tear- off from its neck during stripping from a mould, and hence, it does not has stripping problem.

In accordance with one of the embodiments, the present invention relates to a process for manufacturing a laminated seamless bladder, wherein it does not has drying problem, and therefore, does not has cracks in the bladder.

Accordingly, in one embodiment, the present invention also relates to a process for manufacturing a laminated seamless bladder from a synthetic latex, wherein the bladder not only has judicious combination of good air retention characteristics and good bounce characteristics, but also has further enhanced controlled inflation characteristics, and is still suitable for hand stitched as well as machine stitched inflatable balls, and wherein the process comprises following steps: - a) cleaning the multiple moulds by rinsing in an acid bath; b) heating the rinsed formers obtained from process step - a) by dipping in hot water; c) dipping the heated moulds from process step - b) in a coagulant bath; d) drying the coagulant coated formers obtained from process step - c); e) dipping the dried and coagulant coated formers obtained in process step - d) in compounded synthetic latex bath; f) drying the latex coated coagulated films obtained from process step - e); g) beading the substantially dried latex coated coagulated films obtained from process step - f) to form a bead followed by leaching; h) drying and vulcanizing the leached formers with inner layer of the bladder obtained from process step - g); i) cooling and washing the vulcanized inner layer of the bladders obtained from process step - h); and j) stripping the cooled and washed inner layer of the bladders obtained from process step - i) from the respective moulds [formers]; wherein the process is characterized by:- the synthetic latex being carboxylated acrylonitrile butadiene latex or its blend and no other latex, which is laminated with a rubber; dipping the moulds in a coagulant bath while these are hot and having a temperature varying from about 50 ⁰ C to 70 ⁰ C, and the coagulant bath is maintained at a temperature varying from about 20 ⁰ C to about 80 ⁰ C;

dipping the dried and coagulant coated formers in a compounded latex bath of carboxylated acrylonitrile butadiene latex when it is maintained at a temperature varying from about 10 ⁰ C to 30 ⁰ C; fixing an airinlet valve on the inner layer of the bladders obtained from process step - j); the inner layer of the bladders with airinlet valve are coated with an adhesive capable of bonding the inner layer with a laminate of present invention and the adhesive coated inner layers are dried; the laminate of the present invention is pasted onto the adhesive coated inner layers to result in a bladder having inner and outer layers; the laminated seamless bladders obtained herein are vulcanized to result in laminated seamless bladder of the present invention.

In accordance with present invention, the moulds after vulcanization are opened while it is hot, that is without prior cooling which has been found to have advantageϊof increased production rate.

In accordance with present invention, the inner layer of the bladder has been found to act as support for the laminate which acts as outer layer of the bladder which has been found to result in a seamless bladder of the present invention and overcomes drawbacks of the conventionally known moulding processes.

In accordance with the present invention an airinlet valve is fixed on the inner- layer of the bladders before lamination of laminate of the present invention, which has,, been found to have advantage of avoiding the tearing-off of the valve.

In accordance with present invention, the adhesive coated inner layers are dried in a continuous hot air tunnel preferably maintained at a temperature of about 40 ⁰ C to 45 ⁰ C, which has been found to have advantage of holding the laminate layer firmly at all stages, that is before, during and after the step of vulcanization.

In accordance with present invention, the laminate of the present invention is pasted onto the adhesive coated inner layers by employing hydroneumatically and hydrolically operated moulds which has been found to have advantage of resulting in a bladder having inner and outer layers without any wrinkles therein, that is having smooth surface.

In accordance with present invention, the vulcanization of the laminated seamless bladders is carried out under air pressure varying from about 50 to 75 psi while maintaining the temperature varying from about 100 to 180 ⁰ C for a duration preferably varying from about 3 to 30 min, which has been found to have advantage of providing a

bladder having substantially round shape with complete vulcanization to achieve substantially complete cross-linking of the laminate [outer layer] and the latex [the inner layer], and of laminate it self.

In accordance with one of the preferred embodiments of the present invention, the carboxylated acrylonitrile butadiene latex is blended with other latex, which are preferably selected from a group comprising Neoprene Latex, heat resistant grade Natural Latex, styrene-butadiene rubber latex, or mixture thereof.

The blending of the carboxylated acrylonitrile butadiene latex can be carried out in a conventional manner. However, in accordance with one of the preferred embodiments of the present invention, a care is taken that the carboxylated acrylonitrile butadiene latex is blended with other latex by matching its pH with pH of carboxylated acrylonitrile butadiene latex to avoid destabilization of the blend.

In accordance with one of the embodiments of the present invention, the process steps of dipping in coagulant bath and latex bath may be repeated more than once, preferably twice.

In accordance with present invention, the heated moulds are dipped into coagulant bath preferably for a duration varying from about 15 sec to about 60 sec. A care is taken that the moulds are dipped in coagulant bath while these are hot and having a temperature varying from about 50 ⁰ C to 70 ⁰ C. Further, care is taken that the coagulant bath is maintained at a temperature varying from about 20 ⁰ C to about 80 ⁰ C. The dipping, in accordance with present invention, of the hot formers in a coagulant bath respectively having said temperatures has been found to have advantage of resulting in uniform layer of the coagulant coat on the formers.

In accordance with present invention, the dried and coagulant coated formers are dipped in compounded latex bath of carboxylated acrylonitrile butadiene latex preferably for a duration varying from about 15 sec to 300 sec. A care is taken that the dried and coagulant coated formers are dipped in compounded carboxylated acrylonitrile butadiene latex bath when it is maintained at a temperature varying from about 10 ⁰ C to 30 ⁰ C, which the advantage of avoiding partial precure of the compounded carboxylated acrylonitrile butadiene latex, and hence, has been found to have advantage of resulting in a better wet gel strength of latex coating as evaluated by conventional chloroform test. Further, advantages of avoiding precure at this stage includes enhancement of film formation capability of the carboxylated acrylonitrile butadiene latex, and formation of a product having better tensile strength varying from about 120 to 150 kg/cm ² and elongation at break varying upto about 450%.

In accordance with one of the preferred embodiments of the present invention, the latex coated coagulated films are preferably dried in a hot air tunnel. A care is taken that temperature of the hot air tunnel is maintained within a range varying from about 40 ⁰ C to about 60 ⁰ C preferably for a duration varying from about 5 to about 50 min, and which has the advantage of resulting in a uniform drying of the film without formation of cracks thereon, and entrapment of moisture and clogs therein. It has been found that if temperature of the hot air tunnel is maintained below 40 ⁰ C, the duration of drying will substantially increase, which in-turn will enhance the cost of the overall process, and if temperature of the hot air tunnel is maintained above 60 ⁰ C, then cracks are developed, and entrapment of moisture and clogs takes place, which In-turn results in rejection of the end product. A further care is taken that the latex coated coagulated film does not get fully dried, which has been found to have advantage of avoiding delamination of the subsequent latex coating from the coagulated film. However, it may be noted that scope of present invention is not restricted by drying the latex coated coagulated film in hot air tunnel. In one embodiment, it may be dried at ambient room temperature preferably under circulated air. However, if the film is dried at ambient temperature the process duration will substantially increase.

In accordance with one of the preferred embodiments of the present invention, when the process comprises more than once dipping in coagulant bath [first and second baths and so on] and latex bath [first and second baths and so on], then the semi-dried latex coated coagulated films obtained from preceding process step are dipped in second or subsequent coagulant bath preferably for a duration varying from about 5 sec to about 60 sec. A care is taken that the semi-dried latex coated coagulated films are dipped in second or subsequent coagulant bath while these are maintained at a temperature varying from about 20 ⁰ C to about 80 ⁰ C. The dipping, in accordance with present invention, of the semi-dried latex coated coagulated film in second or subsequent coagulant bath having said temperature has been found to have advantage of resulting in continuously reducing water contents of the bath and to have smooth film formation.

In accordance with one of the preferred embodiments of the present invention, when the process comprises more than once dipping in coagulant bath [first and second baths and so on] and latex bath [first and second baths and so on], then the dried and second or subsequent coagulant coated ^~ latex films obtained in preceding process step are dipped in second or subsequent compounded latex bath of carboxylated acrylonitrile butadiene latex preferably for a duration varying from about 15 sec to 300 sec. A care is taken that the dried and second [and so on] coagulant coated films are dipped in second

or subsequent compounded carboxylated aciylonitrile butadiene latex bath when it is maintained at a temperature varying from about 10 ⁰ C to 3OoC, which has the advantage of avoiding partial precure of the compounded carboxylated acrylonitrile butadiene latex, and hence, result in a better wet gel strength of latex coating as evaluated by conventional chloroform test. Further, advantages of avoiding precure at this stage includes enhancement of film formation capability of the carboxylated acrylonitrile butadiene latex, and formation of a product having better tensile strength and elongation. In accordance with present invention, the leached formers with bladder shell are dried at about 40 ⁰ C which is gradually increased upto 90 ⁰ C, preferably for duration of about 10 to 55 min. The gradually drying has been found to have advantage of uniform drying to avoid entrapment of moisture between the films formed.

In accordance with present invention, the vulcanization is carried out in a closed chamber to maintain the desired temperature for the vulcanization.

In accordance with one of the embodiments of the present invention, the coagulant bath comprises:- coagulating agent varying from about 10 parts to about 90 parts by weight of the total weight of the bath composition; parting agent varying from about 2 parts to about 8 parts by weight of the total weight of the bath composition; and optionally comprising a wetting agent varying from about 0.01 parts to about 0.5 parts by weight of the total weight of the bath composition; and optionally comprising a conventional defoamer or surface active agent varying from about 0.01 parts to about 0.5 parts by weight of the total weight of the bath composition; which are dissolved in water.

In accordance with one of the preferred embodiments of the present invention, the coagulant bath comprises:- coagulating agent, which is preferably calcium chloride or calcium nitrate; parting agent, which is preferably bentonite clay; and optionally comprising a wetting agent, which is preferably non-ionic group. In accordance with one embodiment of the present invention, the carboxylated acrylonitrile butadiene latex bath comprises dry parts of:- carboxylated acrylonitrile butadiene latex about 100 phr [per hundred rubber]; ph modifier varying from about 0.3 to about 0.8 phr; surfactants varying from about 0.1 to about 3.0 phr;

activator and vulcanizing agent varying from about 0.5 to about 5 phr; ultra fast accelerator varying from about 1 to about 3 phr; vulcanizing agent varying from about 0.25 to about 3.0 phr; plasticizer varying from about 1 to about 6 phr; antioxidant varying from about 1 to about 3 phr; and optionally comprising one or more of conventional colours, which are dissolved in water to have 25 to 55% of compounded latex bath.

In accordance with one of the preferred embodiments of the present invention, the carboxylated acrylonitrile butadiene latex bath comprises: -

- a ph modifier which is preferably about 2 to 3% potassium hydroxide [KOH] solution; a surfactant which is selected from a group comprising anionic group; an activator and vulcanizing agent which is preferably 50% dispersion of zinc oxide; an ultra fast accelerator which is preferably 50% dispersion of zinc diethyl dithiocarbamate [ZDEC] or of zinc dibutyl dithiocarbamate [ZDBC]; a vulcanizing agent which is preferably 50% dispersion of sulphur or 33% dispersion of diphenilthiourea IOFTU]; a plasticizer which is preferably 50% emulsion of dioctylephthalate; a antioxidant which is preferably 50% dispersion or emulsion of phenol, amine, aniline or hydroquinone.

In accordance with one embodiment of the present invention, the carboxylated acrylonitrile butadiene latex is characterized by:- acrylonitrile copolymer with medium or high acrylonitrile level varying from about

26% to about 39%; solid content varying from about 39% to about 50% of dry rubber contents; pH value varying from about 7.5 to about 8.5; viscosity varying from about 14 to about 65 mPas; surface tension varying from about 30 to about 40 mN/m.

In accordance with one of the preferred embodiments of the present invention, the moulds [or formers] are rinsed in a weak acid bath of an acid selected from acetic acid or nitric acid having acid bath concentration varying from about 2% to 4% by weight in luke warm water.

In accordance with one of the preferred embodiments of the present invention, the rinsed formers obtained from preceding process step are dipped in hot water maintained

at a temperature varying from about 40 ⁰ C to about 90 ⁰ C to heat the moulds [formers] and to further clean them by removal of acid traces therefrom.

In accordance with one of the preferred embodiments of the present invention, the coagulant coated formers obtained from preceding process step are dried in hot air tunnel for a duration varying from about 15 sec to 5 min or at room temperature till the formers get fully dried.

In accordance with one of the preferred embodiments of the present invention, the second or subsequent coagulant coated latex films obtained from preceding process step are dried in hot air tunnel for a duration varying from about 15 sec to 15 min or at room temperature till the films get fully dried.

In accordance with one of the preferred embodiments of the present invention, the substantially dried latex coated coagulated film obtained from preceding process step is subjected to process steps of beading onto neck portion of the former to form a bead which has been found to facilitate its easy stripping without tearing-off at the neck portion followed by leaching in hot water bath to remove excess of unwanted chemicals. ^' _

In accordance with one of the preferred embodiments of the present invention, the vulcanized inner layers are subjected to accelerated cooling and washing by sprinkling of cold water for a period varying from about 5 to about 10 min.

In accordance with one of the preferred embodiments of the present invention, the cooled and washed inner layers in the form of bladder shells are striped manually from the respective moulds [formers].

In accordance with one of the preferred embodiments of the present invention, the inner bladder shells are washed with luke warm water in a centrifuge chamber at a temperature varying from 40 ⁰ C to 60 ⁰ C to remove clay and other unwanted material.

In accordance with one of the preferred embodiments of the present invention, the washed inner bladder shells are dried in hot air tumbler for about 30 to 180 min at a temperature varying from 50 ⁰ C to 100 ⁰ C to remove water contents therefrom.

In accordance with one of the preferred embodiments of the present invention, an air inlet valve is fixed onto the inner bladder shells, preferably at the neck portion and it is sealed to provide air tight joint and to form a bladder suitable for an inflatable ball.

In accordance with one of the preferred embodiments of the present invention, it has been observed that when a laminated seamless bladder is made by process of the present invention described herein for inflatable balls, the bladder has the following characteristics: -

good combination of good bounce characteristics, air retention characteristics and controlled inflation characteristics; modulus varying from about 60 to 80 Kg/Cm ² at 100% stretch [or elongation]; tensile strength varying from about 120 to 150 kg/cm ² ; elongation at break upto about 450%; and thickness varying from about 0.70 mm to 3.0 mm; weight varying from about 700 mg/inch ² to about 1.5 g/inch ² ; hardness varying from about 45 to 75 shore A; uniform weight and no joints; and it is capable of providing required shape and size of the ball and protecting the outer cover of inflatable ball from de-shaping and bursting on inflation thereof.

Further, the process of present invention has been found to have low manufacturing cost without substantial increase in cost of material and process per se and still having increased production rate with substantially reduced capital cost and rejection rate.

The present invention is now explained with the help of following examples which are not intended to limit its scope but are incorporated for the illustration purposes. ^• Example 1:-

The carboxylated acrylonitrile butadiene latex seamless bladder of present invention is manufactured in following steps: - a) Cleaning of moulds [or formers] - multiple moulds [or formers] are rinsed in a weak acid bath of acetic acid having acid bath concentration of 2.5% by weight in hike warm water; b) Heating of the moulds [formers] - the rinsed formers obtained from process step - a) are dipped in hot water maintained at a temperature of about 70 ⁰ C to heat the moulds [formers] and to further clean them by removal of acid traces therefrom; c) Dipping in coagulant bath - the heated moulds from process step - b) are dipped into coagulant bath for a duration of about 5-60 sec while these are hot and having a temperature of about 50-70 ⁰ C and the coagulant bath is maintained at a temperature of about 20-80 ⁰ C to result in uniform layer of the coagulant coat on the formers; d) Drying of coagulant coated formers - the coagulant coated formers obtained from process step - c) are dried in hot air tunnel for a duration of about 15 Sec-5 Min till the formers get fully dried; e) Dipping dried coagulant coated formers in compounded latex bath - The dried and coagulant coated formers obtained in process step - d) are dipped in compounded latex bath of carboxylated acrylonitrile butadiene latex for a duration of about 15-300 sec while

maintaining temperature of compounded carbαxylated acrylonitrile butadiene latex bath at about 10-30 ⁰ C to avoid partial precure of the compounded carboxylated aciylonitrile butadiene latex, and hence, to result in a better wet gel strength as evaluated by conventional chloroform test, and to enhance film formation capability of the carboxylated acrylonitrile butadiene latex, and formation of a product having better tensile strength and elongation; ^N f) Drying of latex coated coagulated film - The latex coated coagulated film obtained from process step - e) is dried in a hot air tunnel while maintaining temperature of the hot air tunnel at about 40-60 ⁰ C for a duration of about 5-50 Min to result in a uniform drying of the film without formation of cracks thereon, and entrapment of moisture and clogs therein till the latex coated coagulated film does not get fully dried to avoid delamination of the subsequent latex coatings from the coagulated film; g) Beading and leaching - The substantially dried latex coated coagulated film obtained from process step - f) is subjected to process steps of beading onto neck portion of the former to form a bead so as to easy stripping of bladder shell without tearing-όff at the neck portion; followed by leaching in hot water bath to remove excess of unwanted chemicals; h) Drying and Vulcanization - The leached formers with inner layer bladder shell are dried at about 40 ⁰ C which is gradually increased upto 90 ⁰ C for a duration of about 10-55

Min to have uniform drying to avoid entrapment of moisture between the films formed, which are vulcanized at a temperature of about 90-170 ⁰ C for a duration of about 10-55 min in a closed chamber, i) Cooling and washing of vulcanized bladders - The vulcanized inner layers of bladder shells are subjected to accelerated cooling and washing by sprinkling of cold water for a period of about 5-10 min; j) Stripping of inner layers of bladder shells - The cooled and washed inner layers of bladder shells are striped manually from the respective moulds [formers]; k) fixing an airinlet valve on the inner layer of the bladders obtained from process step - j), which in subsequent steps act as support for the laminate and the laminate acts as outer layer of the bladder of the present invention;

1) the inner layer of the bladder shells with airinlet valve are coated with latex based curable adhesive to bond the inner layer with laminate of present invention followed by drying at about 45 ⁰ C;

m) the laminate is pasted onto the adhesive coated inner layers by employing hydroneumatically and hydrolically operated moulds to result in a bladder having inner and outer layers; n) the laminated seamless bladders obtained are vulcanized under air pressure of about 60 psi while maintaining the temperature of about 140 ⁰ C for a duration of about 7 min to result in laminated seamless bladder of the present invention and the moulds after vulcanization are opened while it is hot.

The coagulant bath had following composition:-

Calcium Nitrate - 60 Parts

Water -40 Parts

100 Parts

Bentonite Clay - 6-8% of Total Weight

Wetting Agent - 0.1% of Total Weight

Defoamer - 0.05% of Total Weight

The latex bath had following composition: -

Dry Parts

Carboxylated Acrylonitrile Butadiene Latex - 100.00

KOH Solution (2-3% solution) pH Modifier - 0.3-0.8

Surfactants - 0.1-3

Zinc Oxide (50% Dispersion) - 3-5

ZDC (50% dispersion) - 1-3

Sulphur (50% Dispersion) / DPTU 33% Disp. - 0.25-3.0

Plasisizer (DiOctylePhthalate) - 1-6

Antioxidant (Phenol and amine) - 1-3

Colour - As Required

The bladder manufactured by above process was tested and found to have following characteristics:- good combination of good bounce characteristics as well as air retention characteristics; modulus of about 60-80 Kg/Cm ² at 100% stretch [or elongation];

tensile strength of about 120-150 kg/cm ² ; elongation at break of about 450 %; and thickness of about 0.7 to 3.00 mm; weight of about 700 mg/ inch ² to 1.5 g/inch ² ; no joints were observed; and it was found capable of providing required shape and size of the ball and protecting the outer cover from de-shaping and bursting on inflation thereof.