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RES ILIENT BALL Filed Oct. 25, 1935 Mx 'r @W7- Y j Hfr 5 UNlTi-:o STATES PATENT- oFFlcE 115,685 i mzsmm BALL Ernest 0. Dieterich, Akron, Ohio, asslgnor to The B. F. Goodrich Company, New York, N. Y., a corporation of New York Application October 25, 1935, Serial No. 46,771
1n claim. (ci. 21a-sz) the other of two types of core in the construction of resilient balls. One type consists of a sphere of vulcanized rubber loaded with fillers to provide the necessary weight. The second type consists of a hollow shell or bag of vulcanized rubber filled with a paste orwith a liquid which may or may not contain the loading llers. The retaining shell may contain the loading fillers..
Both of these constructions have certain disadvantages. vulcanized rubber cores are relatively expensive to manufacture because of the considerable time and labor required. Liquid cores are diiiicult to produce and maintain in perfect balance, for the fillers in time will -settle out, producing an unbalanced condition which serlously aiects the accuracy of the ilig'ht 'of the ball, while in cores in which the liquid is not weighted, unavoidable variations in the wall thickness of the loaded shell produce a condition of unbalance similar -to that caused ,by thev settling out of the fillers in the liquid. f
This invention consists in manufacturing cores for resilient balls such as golf balls, baseballs and the like, from unvulcanized rubber vwith or without.loading iillers, as required. By aA simple vulcanizing processI provide the unvulcanized core with a thin cover of tough vulcanized rubber to give adequate strength to prevent, when used inY wound balls, the subsequent windings from cutting into the core and to prevent the unvulcanized rubber from flowing into the interstices between the windings. Alternatively, the core may comprise a pellet of unvulcanized rubber and a separate surface layer of vulcanized rubber surrounding the pellet. v
It has been discovered that the resilience of unvulcanized rubber compressed by the pressure produced by` the windings, when subjected to 'impacts of very short duration. such as the impact of a golf club, is as great as, or greater than, that of vulcanized rubber or of a paste or liquidlled container Ysimilarly enclosed in windings under tension. Furthermore, it is simplev and inexpensive to manufacture such anunvulcanized core, for it is unnecessary to use much ofv the expensive equipment required forthe conventional cores. l
'Ihe foregoingl and other objects, features and advantages of my invention will be clearly understood from the following description and the ac- -ingredients used in the rubber industry.
companying drawing in which Fig. 1 represen a cross-section of an integral core, Fig. 2 a similar section of a core provided with a separate covering layer, and Figs. 3 and 4 represent sections of golf balls containing such cores.
Rubber is plasticized in any standard rubber plasticizing machine such as a roll mill, or an internal mixer, or any other type of masticating machine, until it has been reduced to the consistency desired. Alternatively, the rubber may be broken down to the extent required by the application of heat and/or by the addition of chemii' cals which produce the required effect orby any other means. Fillers to give the desired loading may be added at any convenient stage in the process. The preferred end desired is a soft, highly plastic mixture which may be molded to the required shape easily and may be produced by any method preferred. Although subsequent processes are more easily carried out if the rubber is well broken down, it may be 'of advantage for some applications to masticate the rubber only slightly, and I do not desire to limit the scope of my invention to highly plasticized rubber alone, but to include rubber of all degrees of plasticity.
. The term rubber where used in these specications and claims is intended to include India rubber, Pontianak, guayule and other rubber-containing gummy vegetable exudates, as well as vulcanizable synthetic rubber-like materials, reclaimed rubber and whether admixed with iillers, pigments, colors, and/or any other compounding After the proper degree oi mastication and mix` ing has been attained, the rubber composition is formed into the shape of a spherical pellet of the proper size and weight by any convenient method.V This may be done by cutting it into pieces of proper weight and molding by hand. The rubber compound may be extruded from a tubingma-A chine and formed to the proper shape in a mold with or without the application of external heat,
or by any other convenient means known to the molding art. Y
After the core hasbeen formed the outer layer, may be vulcanized. The preferred method comprises the immersion of the core in a solution of sulfur chloride for an appropriate length of time, depending upon the thickness of the vulcanized covering lto be produced. However, any other means of vulcanizingmay be employed such as the Peachey process, or vulcanization by means of siLlfur, or, polysuliides, or any other method known to the art. If necessary, vulcanization is followed by neutrahzation and washing. If a. separate covering layer is used. the unvulcanized pellets are coated with a suitable rubber composition preferably by dipping in a liquid dispersion of rubber such as latex or a rubber solution or by encasing it in a shell of rubber by a molding process, or even, if desired, by slipping it into a previously vulcanized rubber bag. The coating may contain vulcanizing agents, or may even contain ingredients which interact with others present in the under-lying pellet to bring about vulcanization of the coating.
' As a speciilc example of one embodiment of the invention, an imvulcanized rubber composition is4 preparedbymixingintheusualway 385 partsby weight oi' smoked sheet rubber, an equal quantity oi-guayule rubber, 16 parts oi parailln and 784 parts of Vred iron oxide. This composition is molded into spherical pellets of the desired size by any suitable means, such as a mechanical molding press, and the pellets are immersed for 120 seconds in a 2% solution of sulphur chloride in benzene. trated in Fig. 1, consist of a body Ill of unvulcanized rubber and an integral surface Il of vulcanized rubber. These balls may be used as playing balls or may be used as cores for wound balls such as goli' balls or baseballs. For example, if golf balls are to be made, they are enclosed in a winding, the nrst layer i3 (Fig. 3) of which may be made from a moderately wide rubber tape, and the remainder il from rubber thread, both being wound under tension, and then provided with a tough molded cover l5 of gutta percha or rubber. 'I'he winding is most readily applied if the core is first thoroughly chilled to stillen or freeze the rubber, which prevents the initial convolutions o! the winding from distorting the core.
- The composition of the unvulcanized rubber is lsubject to wide variations, depending on the specific gravity and other characteristics desired. 'Ihus other fillers such as white lead or litharge may be substituted for the red iron oxide and the proportions may be modified to produce any desired weight, plasticity, etc.
In case it is`preferred to apply a separate vulcanized surface layer i2 to the unvulcanized center Il (Fig. 2), a spherical pellet may be molded from the composition recited above, may' be impaled on a wire and dipped in a liquid latex composition containing the quantity of concentrated latex containing 100 parts of rubber along with 1.5 parts of zinc oxide, 1.5 parts of sulphur and 0.5 part of tetramethyl thiuramdisulphide. The latex film is dried, the ball is removed from the wire, the hole leit by the wire ispatched with a drop of the same liquid which is also dried, then the coating is vulcanized, say in boiling 30% calcium chloride solution for an hour, and then rinsed and dried.
Alternatively, the vulcanized layer I2 may be applied to the unvulcanized core III by molding, say in a two-part mold which vforms two sheets of vulcanizable rubber around the spherical core,
'squeenes them together to form a circumferental seam and pinches oi! the excess. The surface layer is then vulcanized in any suitable manner, for example by immersion in 'a heated iiuid as described above, or in a heated mold, the method, temperature and time of vulcanization depending on the composition of the vulcanizable coating.v
The unvulcanized rubber spheres il provided with separate surface layers I 2 of vulcanized rubber may be used as cores for golf balls by providing them with successive windings i3 and Il of rubber tape and thread and a cover l5, as is shown in Fig. 4.
Prom the foregoing description, it is evident to anyone skilled in the art that mymethod of 'Ihe balls thus produced, as illusalmost making cores of resilient balls oil'ers many economies in manufacture. It is merely necessary to plasticize the rubber, mix it with the appropriate llers, mold it yto the required form and vulcanize a surface layer on the outside of the core. It obviates the use of much expensive, cumbersome machinery and greatly reduces labor requirements.
-By means of a mechanical driving machine designed to deliver identical impacts to successive 'balls and vsubstantially duplicating the tee shot in the conventional golf game, it has been established that golf balls made according to this invention are equal to or superior to the standard golf ball in distance otilight.
It is understood that I d o not wish to limit my invention to the speciiic embodiments described above, for the proportions of dillerent ingredients must necessarily be varied through a wide range in order to be adapted to resilient balls of all kinds, and the details of procedure are subject to considerable variation without departing from the spirit of the invention as hereinafter dened.
l. The method of making a resilient ball which comprises coating a solid sphere of unvulcanized rubber with a thin layer of vulcanizable rubber and vulcanizing the latter.
2. The method of making a resilient ball which comprises coating a s'olid sphere of unvulcanized rubber with a thin layer of vulcanizable latex,
- drying the latex and vulcanizing the coating.
.sioned rubber threadV thereon, and applying a molde'd cover.
6. The method of making a golf ball which comprises forming weighted unvulcanized rubber into a solid sphere, providing it with an imd perforate surface layer of vulcanized rubber, winding a tensioned rubber thread thereon. and applying a molded cover.
'1. A ball comprising a solid sphere consisting throughout of resilient rubber, of which the major portion is unvulcanized rubber and the surface is an imperiorate layer of vulcanized' rubber.
8. A golf ball comprising a solid sphere lconsisting throughout of resilient rubber, of which the major portion is imvulcanized rubber and the surface is an imperforate layer of vulcanized rubber, a iensioned winding of rubber on the sphere, and a cover.
9. The method of making a resilient ball which comprises forming a mass of unvulcanized rubber. into a solid sphere and providing it with an imperforate surface layer of vulcanized rubber.
10. The method of making a resilient ball which comprises forming a mass of unvulcanized rubber into a solid sphere and superilcially vulcanizing the rubber of the sphere.
ERNEST O. DIETERICH.