US2589394A - Flexible metal compounds - Google Patents

Description

March 18, 1952 J. F. JOY 2,589,394

FLEXIBLE METAL COMPOUNDS Filed June 15, 1946 Fig. 1.

M 'ENTOR.

Joseph F Joy.

AT RNE Y.

Patented Mar. 18, 1952 FLEXIBLE METAL COMPOUNDS Joseph F. Joy, Pittsburgh, Pa., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application June 15, 1946, Serial No. 677,064

3 Claims.

My invention relates to flexible metal compounds, and the principal object of my invention is to provide new and improved compounds of the character described, and new and improved processes for producing same.

In the drawing accompanying this specification, and forming a part of this application, I have shown, for purposes of illustration, an embodiment which my invention may assume, and in this drawing:

Fig. l is a perspective view of a sheet of material embodying the invention.

Fig. 2 is an enlarged longitudinal sectional view corresponding generally to the line 2--2 of Fig. 1.

Fig. 3 is an enlarged fragmentary sectional view illustrating the embodiment of the invention.

Fig. 4 is a sectional view similar to Fig. 3, but showing the material under tension.

Fig. 5 is an enlarged fragmentary sectional view illustrating a metal particle as it is contained within the flexible body.

Flexible metal compounds forming the subject matter of this invention have a multitude of uses and applications, and are particularly useful in apparatus wherein fluids are employed for the fulfillment of certain functions. Such flexible metal compounds have particular application as seals for pistons, rod packing, and rotary shaft seals wherein the sealing means should be impervious to passage of fluid therethrough, yet be sufficiently resilient to seal against fluid passage therearound. However, it is to be understood that my invention is not limited only to those applications herein disclosed.

I am aware of the fact that metallic particles have been used heretofore in various quantities for the so-called loading of rubber compounds, but I have found that merely loading of rubber with metal particles is not sufficient, since under certain conditions, such as when the compound is placed under tension, there is a tendency of the rubber to pull away from the individual metal particles, thus leaving countless voids in the compound which defeat its purpose as a sealing means, and also which lead to an early physical destruction of the compound. My invention contemplates bonding of each individual metal particle to the flexible carrier material, so that, for instance under tension, the carrier material will stretch between particles, instead of stretching as a flexible body generally. Thus when tension is removed, each individual particle will still have bonded contact with the adjoining carrier material, and the destructive voids hereinbefore mentioned are completely eliminated. In view of this, it will be appreciated that my improved compound has physical properties superior to those possessed by compounds disclosed by prior art.

The metal to be used in the compound is dependent largely on the use to which the compound is put. For example, where antifriction and heat conducting properties are of prime importance, a copper bearing metal may be preferred. On the other hand, where weight is of prime importance, such as is the case in balloon linings, a metal such as aluminum or magnesium may be preferred.

In the compound hereindisclosed, the metal is the preponderant ingredient, and it is introduced into the compound preferably in the form of finely powdered dust, the dust particles being held in closely associated relation by means of a flexible binder. It will be appreciated that in such compound, the metal provides antifriction and fluid sealing qualities, and the binder provides the flexible qualities. By reason of the preponderant metal content, particularly with respect to certain types of metal, the compound has relatively high thermal conducting properties, and this is of importance in cases of seals and the like.

As an example, my compound has been successfully used for forming the sealing lips of piston and rod packings and of rotary shaft seals employed for confining oil and gas within the recoil mechanisms of heavy guns. In modern mechanisms of this type, fluid pressures as great as three thousand (3000) pounds per square inch are common, and piston speeds exceeding fifty (50) feet per second frequently occur. These elements of pressure and piston speed contribute to gun carriage lightness and rapidity of gun firing capacity and are therefore highly desirable. Yet, the achievement of such pressures and speeds impose severe operating conditions upon the sealing members. Since the slightest loss of fluid may impair the efficiency of, or totally render inoperative, such mechanisms, the sealing action should be as nearly absolute as is possible.

Operation under heavy pressures and high piston speeds causes generation of considerable heat because of frictional rubbing contact between the relatively moving parts. Therefore, it is highly desirable to conduct heat away from the rubbing surfaces and dissipate it in the surrounding atmosphere, and my compound, be

cause of its high metallic content, is extremely suitable for this purpose.

In the drawing, my compound has been shown in sheet form, such as the sheet Ill, although it will be appreciated that the compound may be formed to any other shape, and may be molded or otherwise shaped to any desired finished form.

The flexible binder in the illustration shown in the drawings is rubber, as shown at H, although any other suitable flexible or resilient material may be used which is capable of having metal bonded to it in such manner as to provide the desirable qualities of the rubber-metal combination herein disclosed. Since seals, at least in certain cases, are required to resist deterioration caused by contact with oil and other materials, it has been found preferable, although not essential, to use a flexible binder that will resist such deterioration. Synthetic rubbers, at least of certain types now commercially available, have been found to suit such purpose admirably.

The metal, represented by the numeral l2 in the drawings, may take any form, this being dependent largely upon conditions which are to be fulfilled. Therefore, it will be appreciated that the size and shape of the metal particles may be varied without departing from the spirit of my invention.

In addition to the metal particles and the flexible binder, certain other materials may be required to complete the compound, these materials varying in chemical composition and proportion depending upon the flexible binder used and the conditions to be fulfilled.

As an illustrative example of the ingredients which may be used in producing my flexible metal compound, I offer the following formula and process:

mentioned ingredients comprises thoroughly stirring into the metallic powder approximately fifty (50) parts by weight of a bonding agent for the purpose of coating the surface of each metallic particle so as to cause the final compound to become a closely bonded flexible metal product.

As an example of a suitable bonding agent, I have used a commercially available chlorinated rubber base cement sold under the trade name of Ty-Ply. The composition of Ty-Ply is disclosed in U. S. Patent No. 2,259,190, on page 1 at lines 10 to 14, as a liquid coating composition comprising chlorinated rubber capable of curing to a relatively non-thermoplastic adhesive product on drying and heating, and is specifically claimed (claim. 1) as a cement consisting essentially of rubber chloride, a volatile solvent, sulfur, and a minor amount of an organic accelerator for the vulcanization of rubber. However, it will be appreciated that other chlorinated rubber adhesives may be used in the carrying out of my invention.

The mixture of metal dust and bonding agent should be subjected to sufflcient heat to drive off the moisture until the mixture takes a crust-like appearance, at which time it is ready for milling n 1 Ingredients Metallic powder, preferably particle sizes ranging be tween 8 and 20 microns 140. 0 Neoprene G RM" (or Neoprene GN as it was iorm erly designated) 54. 0 Retarder W (Salicylic Aci 2. 0 Magnesia Oxid 2.0 Neozonc D i .6 Zinc Oxide l. 5 Cumar 2. 6 gil (Circo Light Process) crm Total Parts 207. 7

Viscosity 100 F 150-160 Flash ASTM open cup 325-330 Fire 370-380 Pour test ASTM 30 F. Max.

NPA color 2 Demulsibility Good Conradson carbon .02

Neutralization No. Neutral Neozone is basically a napthylamine used as an antioxidant and is specifically known as phenyl-beta-napthylamine.

The preferable method of processing the aforeinto the other ingredients.

The remainder of the mixture may be prepared by milling the neoprene GR-M just the same as when it is to be used for the processing of synthetic rubber parts, adding the retarder W as the neoprene stock warms up. The magnesia oxide, neozone D," zinc oxide, cumar, Circo light process oil, and acrin may be added to the neoprene GR-M, and the milling may be continued until the stock is well mixed. This, according to the above proportions, will make 67.7 parts which is used to form the flexible binder for the final flexible metal compound.

The flexible binder may then be added to the coated metallic particles, and the mixture milled until thoroughly mixed. Thorough mixing may be determined by sheeting and cutting into strips, and examining the edges of the strips for evidence of segregations of metal particles. When the metal particle dispersion is uniform, the mix is ready for molding and curing or vulcanizing, which comprises applying heat at approximately 307 F. for about twenty-five (25) minutes. The mix, prior to vulcanizing, is moldable, and gaskets, seals, packing and other products may be molded to any desired shape and form.

For certain purposes, such as for certain seals, I have used commercially available bronze powder as the metallic particles, and using substantially the aforementioned proportions, the resultant product had the following physical properties:

Elongation per cent 250 Tensile strength to the square inch pounds 600 Hardness (durometer test) do It will be appreciated that changes in metal, or in other ingredients, or in proportions of ingredients within limits, will vary the physical properties of the compound without departing from the spirit of the invention.

Referring to Fig. 5 of the drawing, it will be seen that each metal particle is provided with a coating 13 of bonding agent, which coating is left after the mixture of metal dust and bonding agent has been subjected to sufficient heat to drive off the moisture. Therefore, the entire exterior surface of each metal particle will have a good lasting bond with the adjoining flexible binder, such as the rubber shown. This bonding agent should not be confused with other coatings for the metallic particles, as taught by the prior art. Such coatings are only for the purpose of preventing the metal particles from lumping or coalescing, and in no manner do they provide for secure connection between each metal particle and the adjoining flexible binder. Attention is directed to Fig. 4 of the drawings, wherein the flexible compound is shown under tension. Comparison of this figure with the construction shown in Fig. 3 will clearly show that the metal particles are securely attached to the rubber, and the rubber stretches intermediate the particles. This, at least in part, explains the very desirable physical properties obtainable with compounds made in accordance with my invention. The term a rubber as used in this application is intended to designate both natural and synthetic rubbers capable of being vulcanized, and the term a vulcanized rubber and like terms to include such rubbers in a vulcanized condition.

From the foregoing, it will be apparent to those skilled in the art, that I have accomplished at least the principal object of my invention; and it also Will be apparent to those skilled in the art that the embodiments herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence, it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

What I claim as new and desire to secure by Letters Patent is:

1. A flexible compound having relatively high thermal conducting properties comprising a vulcanized rubber body, finely divided metallic particles intimately dispersed throughout said body, and a film of a vulcanized chlorinated rubber base cement coating said particles and firmly bonding them to said body, said particles cumulatively constituting a preponderant portion by weight of said compound.

2. A flexible compound comprising a vulcanizizable mass of a rubber, having thickly dispersed therethrough and embedded therein metallic particles coated with a chlorinated rubber adhesive, said mass and said particles integrated into a body by the vulcanization of said mass and the coatings of said metallic particles, and said ch10- rinated rubber adhesive bonding the rubber to the metallic particles.

3. The method of making a flexible metallic product having relatively high thermal conducting properties suitable for seals between relatively moving contiguous elements which comprises wetting particles of a finely divided mass of metallic particles with a chlorinated rubber base cement, evaporating the solvent from the cement, dispersing the treated particles throughout a vulcanizable rubber mass, in such proportions that the metal is a preponderant portion by Weight of the mixture, and vulcanizing the resulting mixture to form a strong integral flexible metallic product.

JOSEPH F. JOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,438,735 Williams Dec. 12, 1922 2,084,784 Stahl June 22, 1937 2,286,260 Carter June 16, 1942 2,377,153 Hunter May 2-9, 1945 OTHER REFERENCES The Duprene Manual, published August 1, 1934, by E. I. Du Pont 00., pages 43-44, 56.

India Rubber Journal, February 29, 1936, page 253.

Du Pont Rubber Chemical, published February 1943, by E. I. Du Pont 00., pages 105-106, -76 and 21-22.

Claims (1)

1. A FLEXIBLE COMPOUND HAVING RELATIVELY HIGH THERMAL CONDUCTING PROPERTIES COMPRISING A VULCANIZED RUBBER BODY, FINELY DIVIDED METALLIC PARTICLES INTIMATELY DISPERSED THROUGHOUT SAID BODY, AND A FILM OF A VULCANIZED CHLORINATED RUBBER BASE CEMENT COATING SAID PARTICLES AND FIRMLY BONDING THEM TO SAID BODY, SAID PARTICLES CUMULATIVELY CONSTITUTING A PREPONDERANT PORTION BY WEIGHT OF SAID COMPOUND.

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