GB2138015A - Inflation needle lubricating plug insert-type valve assembly - Google Patents

Abstract

A self-lubricating plug insert- type valve assembly is provided for use with inflatable articles of manufacture, such as footballs, basketballs, etc. In the assembly a sealing plug (17) comprises a self- closing passage (18) through which an inflation needle (22) is inserted; the plug is characterized by containing a lubrication-effective amount of a silicone grease. Although contained as part of the rubber mix from which the plug is formed, the grease migrates from within the plug and forms a continually renewed lubricant coating along the self-closing passage. <IMAGE>

Description

SPECIFICATION Inflation needle lubricating plug insert-type valve assembly The field of this invention relates to inflation valve assemblies of the plug insert-type. Such valve assemblies have been commonly employed with inflatable balls, such as footballs, basketballs, etc., which include a bladder within an outer covering. The assembley comprises a housing which is sealed to the bladder and provides a passage extending from the outside of the ball to the interior of the bladder, and the passage also includes a chamber which receives the sealing plug. To inflate the ball, an inflation needle is extended into the ball through the plug, usually through a preformed passage. Such valve assemblies are disclosed, for example, in United States Patents 2,935,320, 3,100,498, 4,311,307 and 4,341,382.

When valves of the plug-insert type are used for balls for vigorous sports such as basketball, football, soccer, etc., as well as in playground balls and punching bags, the valves are subjected to extreme use conditions at both indoor and outdoor temperatures. Further, to keep the balls at the proper air inflation for optimum performance frequent additions of air are required. This means that the inflation needle is repeatedly inserted through the valve plugs and removed therefrom under a variety of temperature and weather conditions. It has been found that valve failures resulting in leakage of air through the valve occur primarily because of the deterioration of the sealing plugs. For example, the plugs may take a "compression set", which interferes with the sealing engagement between the outside surfaces of the plug and the valve housing within which it is secured.Even more frequently, the insertion and/or removal of the needle cause tearing or enlargement of the passage through which it extends. This interferes with the self-closing action of the passage on withdrawal of the needle. Although lubrication of the inflation needles by users could help to alleviate the problem, it has not been found practical to instruct users to carry out such lubrication.

One attempt to solve this problem has met with a limited degree of success with respect to a valve used in basketballs. The needle insertion passage of the plug was provided with an enlarged recess or "sump" into which the manufacturer inserted a small quantity of liquid glycerin. Then in the filling of the balls passage of the inflation needle through the glycerin containing sump will provide a lubricant coating on the needle, which will be spread to some extent over the surfaces of the passageway. It was found, however, that the supply of glycerin in the sump is rather quickly used up, long before the end of the useful life of the ball and valve assemble. Further, this sump valve design did not lend itself to use with balls, such as footballs, where the bladders are not bonded to the covers. The glycerin-containing valves therefore have received only limited commercial use.

A plug insert-type valve including a liquid-receiving sump is disclosed in United States Patent 2,934,344. As described in that patent, the sump is not used to provide a lubrication action.

Instead, the sump is designed to collect liquid plasticizer exuded by the plug which is formed from a plasticizer-containing plastic resin. As described, the viscous plasticizer in the sump provides a sealing action, which assists in maintaining an air-tight seal.

This invention is based on two interrelated discoveries. First, it has been found that the plug inserts for valves of the plug sealing type provide better and longer performance under field conditiions of use if prepared from rubber mixes which on being molded and cured provide a soft, deformable, resilient character to the plug. Such properties are most easily obtainable by using a rubber mix in which the rubber is substantially entirely natural rubber. Where substantial amounts of synthetic rubber are present, the plugs may not have adequate resilience or recovery from deformation, in effect, taking a compression set. Further, as the snythetic rubbers like neoprene degrade, such as by oxidation, they tend to become harder and more brittle. Rubber formulations based on natural rubber, however, tend to become softer as they are subjected to oxidation.

Secondly and of even greater importance for maximizing valve life, it has been found that the plugs can be made self-lubricating by incorporating a minor proportion of a silicone grease in the rubber mix. For example, as little as five parts of a dimethyl polysiloxane grease per 100 parts of natural rubber provides an effective long-term lubracting action. Although the silicone grease is included in the mix prior to it being molded and cured, it is not completely locked within the plug, but rather remains free to migrate. It has been found that a sufficient amount of the silicone grease within the plug reaches the needle insertion passageway, and, in effect, bleeds into the passageway so that the needle is effectively lubricated.Further, the repeated insertion and the withdrawal of the needle tends to "work" the walls of the plug passage, promoting the release of the silicone grease and its distribution within the passage. Friction between the needle and the plug is thereby greatly reduced, and there is less tendency for the plug to become distorted, or to take a compression set, and the plug is also effectively protected against gouging or tearing by the needle.

The maximum period of time in which the silicone grease will provide effective lubrication for the needle passage has not been determined, but appears to be very much longer than the lubrication previously provided by the glycerin-containing sumps. It is believed that the lubricating action can be expected to continue throughout the useful life of the ball and bladder.

Moreover, this lubrication does not appear to be temperature dependent. It remains effective under cold ambient conditions, such as in outdoor football use, as well as at indoor temperatures.

Valve assemblies utilizing inserts formed in accordance with the present invention are illustrated, by way of example only, in the accompanying drawings, wherein Figs. 1-4 illustrate a valve adapted for use with a football; Fig. 5 an alternative design of a football valve; and Fig.

6, a valve assembly particularly adapted for use with basketballs. The insert plugs of all of these valve assemblies are formed from a rubber-based mix containing an effective lubricating amount of a silicone grease.

The valve assembly of this invention is useful for any inflatable objects of manufacture. The assembly includes a valve body providing a passage therethrough with a chamber portion, and a sealing plug inserted within the chamber portion and retained therein in sealing engagement with the adjacent wall portions of the passage. The plug is pierceable by an inflation needle to permit gas, usually air, to be forced into the inflatable article. The valve assembly has particular utility for use with balls having bladders, which may be attached or unattached to the covering of the ball. Such balls, for example, include footballs, basketballs, soccer balls, and the like. In general, these are premium balls which are used for long periods of time under strenous conditions.Valves can also be used for analogous purposes such as in punching bags, and may even be useful in less expensive balls such as ordinary playground balls.

The valve bodies may be formed of a wide variety of moldable materials, such as plastics, synthetic rubber, natural rubber, etc. The valve bodies which provide the housing for the insertable plugs are relatively rigid, as compared with the plugs. It is the plugs which are deformed to force them into the chambers of the valve bodies so as to be retained therein in a slightly compressed condition. The valve bodies therefore may be formed of well known, conventional materials. For example, one suitable material for general use is a urethane-type rubber, such as a polyester-based urethane.

This invention concerns particularly the formulation of the sealing plugs, and the resulting properties obtained when the plugs are molded and cured. In general, the cured plugs should provide the characteristics or properties of being soft, deformable, and resilient. By "resilient" it is meant that the plugs exhibit a high degree of recovery on being compressed or deformed.

Although the plugs may be formed of rubbers other than natural rubber, or of mixtures of natural rubber and synthetic rubber, it is preferred to utilize natural rubber as the primary elastomer. For example, optimum formulations contain the natural rubber as the only elastomer.

In accordance with the present invention, a minor proportion of a silicone grease is incorporated in the rubber mix before molding and curing, being uniformly distributed therethrough in the preparation of the mix. A sufficient amount of the silicone grease should be used to provide an effective lubricating action but not so much as to create any mechanical problems in preparing and molding the mix. Silicone greases are in paste or serni-liquid condition. Further, they are relatively expensive compared to other ingredients of the mix, and therefore it is undesirable to employ large excesses. In general, amounts of silicone grease in the range of 1 to 1 5 parts by weight per 100 parts of the rubber can be employed.The effectiveness of the lubricating action increases appreciably, especially for long term use of the valves, within the range of from 1 to 3 parts of silicone grease per 100 parts of rubber.

Therefore it is preferred to employ at least 3 parts of the silicone grease. For example, excellent lubricating properties are provided using 5 parts of the silicone grease per 100 parts of rubber.

To assure maximum continued effective lubrication, more than 5 parts can be employed, but usually there will be no advantage in employing more than 1 2 parts of the silicone grease per 100 parts of rubber. A preferred silicone grease, which is readily available from commercial sources in the United States, is dimethyl polysiloxane grease. However, other silicone-type greases having similar properties can be employed.

It should be understood that the silicone grease containing rubber mix will also be formulated with standard or conventional ingredients for preparing molded rubber products having the desired properties of softness, deformability, and resilience. These will usually include process oils, such as napthenic oil, zine oxide, either with or without other fillers, such as silica flour, and carbon black, and cross-linking agents, such as particularly sulphur. The curing of the rubber during the cross-linking reaction may be controlled by the use of regulators including accelerators and/or retarders. For example, the accelerators may be benzothiazole disulfide, diphenyl guanidine, etc. The retarder may be salicyclic acid or phthalic anhydride. In addition, antioxidants will usually be included to protect the cured composition against air oxidation. For example, such antioxidants include Antioxident 2246, and Santovar A.

It will also be understood that the rubber mixes may be colored by the addition of pigments.

When carbon black is employed as a filler, a black color will be obtained, but for other colors, such as green, or red, the use of pigments is needed.

An illustrative general formula for the rubber mixes of this invention is set out below.

General Formula Ingredients Parts by Weight Natural Rubber 100 Silicone Grease 1- 1 5 Process Oil 5- 25 Zinc Oxide 5- 30 Silica Flour 0- 25 Carbon Black 0- 25 Sulphur 2- 3 Accelerators 0.95- 3.0 Retarders 0- 1.5 Antioxidants 1- 2 Pigment 0- 1 Turning now to the accompanying drawings, three valve assemblies are shown having valve inserts which may be made in accordance with the present invention. The valve of Figs. 1-4 is designed for use with a football. It includes a valve body designated generally by the number 10, which includes a passage 11 therethrough. The enlarged housing portion 1 2 provides a chamber 1 3 having spaced circumferential ribs 14.Also, integrally formed with housing 1 2 and immediately thereabove is an outwardly extending flange portion 15, which is centrally connected to an upwardly projecting nipple portion 1 6. Passage 11 extends through the nipple portion 16, as shown.

The insert plug for the valve body of Fig. 1 is shown in Figs. 2 and 3. It consists of a cylindrically shaped plug 17. Through the center of the plug 17 there extends a self-closing passage 1 8. Preferably this passage is preformed to guide the insertion of the needle. It will be understood that plug 1 7 is formed of the silicone grease-containing rubber mix, as described above, which is preferably a natural rubber mix containing from 3 to 1 2 parts of dimethyl siloxane grease per 100 parts of rubber. In the assembly of the valve, the soft, deformable, resilient plug 1 7 is forced into the chamber 1 3 through the lower end of passage 11, and is seated within the chamber as illustrated in Fig. 4.The ribs 14 press against and sealingly engage the side walls of the plug, which is dimensioned so that it is maintained in a slightly compressed condition when inserted. This slight compression assists in retaining the plug and also promotes the self-closing action of the passage 18.

As shown in Fig. 4, the flange 1 5 of the valve body has been vulcanized to the inside wall of a bladder 19, which is contained within a cover 20 in non-attached relation thereto. This assembly is one which could be used in a football. As will be noted, the outwardly projecting portion of the nipple 16 has been cut off immediately above the retaining flange 21. In manufacturing, the outer portion of the nipple 1 6 is used to assist in pulling the valve assembly into proper relation with the cover and bladder, as shown in Fig. 4, and is thereafter cut off to provide an outer surface which is slightly depressed with respect to the outer surface of the cover.

As shown in Fig. 4, an inflation needle 22 has been inserted through the plug 17, the hollow needle including the piercing shaft portion 23, which when fully inserted extends inwardly beyond the valve body, and the outer enlarged threaded end 24 to which the air supply hose is connected.

In Fig. 5, there is shown an alternative valve assembly for use with a football. For convenience of reference, corresponding parts to the valve assembly of Figs. 1-5 have been given the same numbers except that the numbers have been increased by 100. As shown, the valve body 110 which provides the insert receiving passage 111 has an outwardly extending cylindrical portion 11 3a into which is received the collar portion 11 7a of the insert 11 7. The passage 111 is an open bore its upper end down to the solid bottom portion 117b, which is provided with a self-closing slit 11 8a that communicates with the lower end of the passage 118, and performs the same function as passage 118 in the embodiment of Figs. 1-4.As explained in connection with the prior embodiment, the bladder and ball cover will be received between the flanges 115 and 121, the top of the flange 11 5 being bonded to the inner wall of the bladder. On completion of the assembly, the insert 111 will be cut off above the flange 121 to provide a completed assembly similar to that shown in Fig. 4.

The valve assembly of Fig. 6 is particularly adapted for use with a basketball. For convenience of reference, the same numbers have been used as with respect to the embodiment of Figs.

1-4, except that the numbers have been increased by 200. As will be noted, the valve insert 217 includes circular recesses 21 7a which receive and interlock with the annular ribs 214 provided on the walls of the enlarged chamber portion 21 3 of the valve body 210. The lower end of the opening 211 is of restricted cross-section. With this embodiment, the valve body can be inserted through the upper end of the opening 211. A self-closing passage 218 is provided through the center of plug 217, construction and operation of the passage being the same as that described with respect to passage 1 7 of plug 18. As will be appreciated, therefore, the insert plugs may be made in various sizes and shapes, using the formulation of the present invention to provide the desirable properties described above.

The application of this invention in commercially desirable embodiments is further illustrated by the following examples.

EXAMPLE I Rubber formulations which may be employed and which are presently preferred for manufacturing the insert plugs of the valves shown in the drawing are as follows: Formula A for Insert Plug of Figs. 2-4 Ingredients Parts by Weight SMR-50-CV (Natural Rubber) 100.00 Circo Light Oil 10.00 Zinc Oxide 10.00 Sulphur 2.50 Stearic Acid 1.00 M.B.T.S. 0.80 D.P.G. 0.20 SF-96 (Silicone Grease) 5.00 Antioxident 2246 1.00 Green Pigment To Tint Effective Cure rate: 7 1 /2 min. at 340"F.

Formula B for Insert Plug of Fig. 5 Ingredients Parts by Weight SMR-50-CV (Natural Rubber) 100.00 Circo Light Oil 10.00 Zinc Oxide 10.00 Sulphur 2.50 M.B.T.S. 0.80 D.P.G. 0.20 Santovar A 1.00 SF-96 (Silicone Grease) 5.00 Stearic Acid 1.00 N-330 Black 10.00 Effective Cure rate: 7 1/2 min. at 340t F.

Formula C for Insert Plug of Fig. 6 Ingredients Parts by Weight SMR-50-CV (Natural Rubber) 100.00 Zinc Oxide 1 5.00 Silene D 15.00 Sulphur 2.00 Santocure 1.20 D.O.T.G 0.60 Retarder W. 1.00 Stearic Acid 1.00 Santovar A 1.00 N-330 Black 10.00 Viscasil 10,000 Fluid 5.00 (Silicone Grease) Circo Light Oil 5.00 Effective Cure rate: 5 min. at 320"F.

The foregoing formulas include trade names and trade designations, which have the following meanings: Formula Chemical Designation Description Source SMR-50-CV Natural Rubber Generally available SMR-5-CV-60 Natural Rubber Generally available Circo Light Oil Naphthenic Oil, Sun Oil Co.

ASTM D-2226, Type 103 Zinc Oxide Zinc Oxide New Jersey Zinc Co.

Sulphur Sulphur Generally available Stearic Acid Stearic Acid Generally available M.B.T.S. Benzothiozol American Cyanadmide Disulfide D.P.G. Diphenyl Guanadine Monsanto SF-96 Dimethyl Poly- General Electric siloxane Grease Antioxidant 2246 2,2'Methylene-bis- American Cyanmide (4 methyl-6- 1 -butyl phenol) Formula Chmeical Designation Description Source Santovar A 2,5-Di(tert-amyl) Monsanto hydroquinone Santocure N-Cyclohexyl-2- Monsanto benzothianzole sulfonamide Viscasii 10,000 Dimethyl Poly- Marnick Chemical Co.

Fluid siloxane Grease Silene D Hydrated Silica Pittsburgh Plate Giass D.O.T.G. Di-ortho toluol Generally available guanidine Retarder W Salicylic Acid Uniroyal N-330 Black Carbon Black Colombian The specifications of the above identified silicone greases are as follows: SF-96 Grease Type: Dimethyl Siloxane Sp. Gr.: 0.97 Non-toxic, odorless, colorless.

Viscasil 10,000 Fluid Type: Dimethyl Siloxane Sp. Gr.: 0.975 Viscosity: 10,000 cps.

Flash Point: 600"F Non-toxic, odorless, colorless.

EXAMPLE II An illustrative manufacturing procedure for formula A is as follows: Time Steps (minutes) (1) 00.00 Add rubber to mill and form band. Cut and blend. Cool.

(2) 03.30 Start adding pre-blended Circo oil, Zinc Oxide and SF-96. Add slowly.

Cut and blend.

(3) 21.00 Add Sulphur, Stearic Acid, and Antioxi dant. Cut and blend.

(4) 24.00 Add Green Pigment, M.B.T.S., and D.P.G.

Add slowly. Cut and blend.

(5) 28.00 Sheet off.

Molding The molding time is 7 1/2 min. Cure at 340"F. The total cycle is 10 minutes in a transferplunger type mold.

Formulas B and C are blended and molded in a similar manner.

Claims (14)

1. A valve assembly for an inflatable article of manufacture including a valve body providing a passage therethrough with a chamber portion, and a sealing plug inserted within said chamber portion and retained therein in sealing engagement with the adjacent wall portions of said passage, said plug being pierceable by an inflation needle to permit gas to be forced into said inflatable article; wherein said plug is formed for a rubber-based mix providing a soft, deformable, resilient character to said plug when molded and cured, and there is present in said plug as part of said mix from 1 to 1 5 parts by weight of a rubber-compatible silicone grease per each 100 parts of rubber, said plug providing a self-lu'bricating action which facilitates insertion and withdrawal of an inflation needle.

2. The valve assembly of Claim 1 in which said plug contains from 3 to 12% by weight of said silicone grease per each 100 parts of rubber.

3. The valve assembly of Claim 1 or Claim 2 in which said silicone grease is a dimethyl polysiloxane grease.

4. The valve assembly of any one of the preceding claims in which the rubber in said mix is composed substantially entirely of natural rubber.

5. The valve assembly of any one of the preceding claims in which said plug has a preformed self-closing passage therethrough to guide the insertion of the inflation needle.

6. A valve assembly for an inflatable ball having a bladder and including a valve body sealed to the bladder, said valve body providing a passage extending from the exterior of said ball to within said bladder, said passage having a chamber portion, and a sealing plug inserted within said chamber portion and retained therein in sealing engagement with the adjacent wall portions of said passage, said plug being pierceable by an inflation needle to permit air to be forced into said ball, wherein said plug is formed of a natural rubber-mix providing a soft, deformable, resilient character to said plug as part of said mix from 3 to 1 2 parts by weight of a dimethyl polysiloxane grease per each 100 parts of the natural rubber, said plug providing a selflubricating action which facilitates insertion and withdrawal of an inflation needle.

7. The valve assembly of Claim 6 in which said plug has a preformed self-closing passage therethrough to guide the insertion of the inflation needle.

8. A valve assembly for an inflatable ball having a bladder and including a valve body sealed to the bladder, said valve body providing a passage extending from the exterior of said ball to within said bladder, said passage having a chamber portion, and a sealing plug inserted within said chamber portion and retained therein in sealing engagement with the adjacent wall portions of said passage, said plug being pierceable by an inflation needle to permit air to be forced into said ball, wherein said plug is formed of a rubber-based mix providing a soft, deformable, resilient character to said plug when molded and cured, the rubber of said mix being substantially entirely natural rubber, and said mix including conventional rubber formulation ingredients selected from the class consisting of process oil, fillers, sulphur, accelerators, retarders, antioxidants, and pigments, and selected mixtures thereof, said rubber-based mix being characterised by containing from 3 to 1 2 parts of a dimethyl polysiloxane grease per 100 parts of natural rubber, said plug providing a self-lubricating action which facilitates insertion and removal of an inflation needle.

9. The valve assembly of Claim 8 in which said plug has a preformed self-closing passage therethrough to guide the insertion of the inflation needle.

10. The valve assembly of Claim 1 or Claim 6 or Claim 8, the assembly being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figs. 1 to 4 or Fig. 5 or Fig. 6 of the accompanying drawings.

11. The valve assembly of Claim 1 or Claim 6 or Claim 8 or Claim 10, the assembly having any one of the rubber formulations described in Example I.

1 2. The assembly of Claim 11 which has been manufactured by the procedure described in Example II.

1 3. An inflatable article of manufacture comprising the valve assembly of any one of the preceding claims.

14. An inflatable ball comprising the valve assembly of any one of Claims 1 to 1 2.