US 1858279 A
Description (OCR text may contain errors)
y 17, J, PARKER 1,858,279
METHOD OF MAKING BOTTLE CAPS Filed March 27, 1930 u I, I I I, I w l 11- I '1 H n I I flNVENT BWQ/ k ATTORNEY- Patented May 17, 1932 UNITED STATES PATENT OFFICE CECIL J". PARKER, OF GOVANS, MARYLAND, ASSIGNOR TO CROWN CORK & SEAL COM- PANY, INC., NEW YORK, N. Y., A CORPORATION OF NEW YORK v METHOD OF MAKING BOTTLE CAPS Application filed March 27, 1930. Serial No. 439,302.
My invention relates to a method of making bottle caps, and more particularly to the production of caps of the type which embodies therein a skirted metal shell having an annular gasket within the shell adjacent the skirt.
Heretofore, in the production of caps of the type to which my invention relates, two practices have been followed. In producing these caps by one of the old methods, rings of soft vulcanized rubber were first formed, and these rings were secured in position in the shell by means of cement or other adhesive. By the other method, caps were produced by flowing a semi-plastic composition of latex and a mineral filler into a channel formed in the top of the shell, the material being allowed to set under normal factory temperatures or gentle heat.
In the former of these methods, the procedure in producing the gaskets and in applying them to the metal shell was costly in the light of the low cost, of the completed product. The latter, method resulted in a cap which was not suitable for use in the closure of containers which, after being capped, had to be subjected to high temperatures for the purposeof sterilization, or the cooking of the contents. Furthermore, a cap of this character could not be effectively used when the pressure developed withinIa container exceeds 75 or 80 pounds per square inch, irrespective of whether this pressure was developed as a result of the subjecting of the container to heat, or from the separation of carbonic acid gas from the contents of the bottle due to other reasons.
With the above conditions in mind, I have developed a method of making bottle caps by which the cost of production of such caps may be very much cheapened as compared to the cap having the vulcanized ring cemented within same, and which will form an effective seal irrespective of the pressure developed within the container, or of the temperature to which same may be subjected after the cap has been applied thereto.
In the practice of the method of my invention, I secure the bonding of the gasket 50 to the metal shell without the employment of a stratum of adhesive between the gasket and the shell, utilizing the adhesiveness inherent to the rubber compound forming the gasket during vulcanization to secure the gasket in position within the shell. v
By the method of my invention I am also enabled to provide a cap wherein the gasket possesses a sufficiently permanent set to ensure an effective sealing action and yet have the gasket free of any uncombined vulcanizing agent which can impart the characteristic flavor of soft vulcanized rubber to the contents of the container, or have any deleterious action thereon.
My invention contemplates not only the employment of a rubber compound having special characteristics for facilitating the production of a gasket having the desired properties, but one which will expedite the production of the cap as a whole While securing an adequate bonding action between the gasket and the metal shell.
The invention consists primarily in a method of making bottle caps embodying therein the extrusion in tubular or annular form of a compound containing rubber, a filler, and a low content of a vulcanizing agent, the separation of the tube, in its unvulcanized condition, into rings, the delivery of such rings to a skirted metallic shell within and adjacent the skirt thcreof,.and the subjection of the metallic shell and its contained ring to a vulcanizing temperature, whereby said ring will be bonded to the metal shell and will be simultaneously semi-vulcanized; and in i such other novel steps and practices as are I hereinafter set forth and described, and more particularly pointed out in the claims hereto appended.
Referring to the drawings,
Fig. 1 is a conventional showing of an ordinary tubing machine;
Fig. 2 is a section of a completed bottle cap made by the method of the invention; and
Fig. 3 is a perspective View of one of the gasket forming rings, prior to its application to the metallic shell.
Like letters refer to like parts throughout the several views.
In the practice of the method of my-invention, I form a rubber compound containing ordinary commercial rubber, a filler of any desired type well known to workers in the rubber making art, a vulcanizing agent, preferably sulfur, the proportion of which to the rubber content of the batch is very much lower than that heretofore used in the rubber making art, and an accelerator, preferably an organic, rapid acting accelerator such as tetra-methyl-thiuram-disulphide.
While generally, in the rubber art, the amount of sulfur used to secure a soft vulcanized product is 3% or more, in the compound above referred to I use only approximately 1% of the rubber content of the batch, thus avoiding any possibility of free or uncombined sulfur in the completed gasket. This compound is produced by the methods usually employed by the rubber maker, the invention relating more particularly to the method of producing a bottle cap, having certain desirable and novel properties, resulting in part from the character of the compound used in the gasket, and in part from the practices followed in assembling gaskets of this compound in the cap structure.
A compound of the character above described is given the desired form and dimensions according to the size and character of the shell of the cap of which it is to form a part, in any desired manner, as by means of a tubing machine as shown at a in the drawings. Ordinarily, a ring gasket is employed.
The material extruded by the machine a is of a thickness to ensure sufiicient body in the gasket. Such a gasket of the ring type is shown at I; in Fig. 3 of the drawings, the tube from which it is out being shown at 0 in Fig. 1. The material of the gasket 7), when cut from the tubing, is plastic.
This gasket is placed in the shell (1 of the cap adjacent the skirt thereof. In the drawings, I have shown the invention in connection with a metal shell of the crown type in which the skirt is fluted to facilitate the attachment of the cap to the bottle or other container. Ordinarily, such shells have a lacquer coated inner surface,-which is highly desirable as facilitating bonding action between the gasket and the shell, irrespective of the character of the gasket used.
The plastic, pre-formed gasket 1) is deposited directly upon the inner surface of the shell, or upon the lacquer coating, when such is used, and adheres: thereto without the necessity for the use of any adhesive between the gasket and the shell. Subsequently, the shell with its contained gasket is subjected to a temperature of approximately 240 F. for a sufficient interval to effectively cure the material of the gasket and to give permanency to the bond between same and the metal shell.
The content of the vulcanizing medium, while sub-normal as known to the rubber making art, is adequate to give the gasket a proper set and resiliency adequate to secure an effective sealing action when the cap is applied to a bottle or other container. The low sulfur content, however, will avoid any possibility of the presence, in the gasket of the completed cap, of free or uncombined sulfur or its presence in sufficient volume to impart any of the characteristic tastes of ordinary rubber having sulfur as a vulcanizing medium, to the contents of a bottle or other container closed by the cap of my invention.
The use of an accelerator permits an approximate control of the time interval, and from a manufacturing standpoint expedites the production of the caps with a minimum of wastage.
The character of the compound used, and the manner of forming and assembling the gasket in the shell permits the production of the cap with as few steps as is practicable while resulting in a product including therein a soft vulcanized rubber gasket bonded directly to the material of the shell.
When using a ring gasket, it is preferable to employ a shell (Z, having formed in the top thereof a channel 6 adapted to receive the gasket, the plastic material of the gasket readily conforming to this channel following the seating of the gasket therein and during the vulcaization stage.
It is not my intention to limit the invention to the particular configuration or dimensions of the gasket or of the shell, nor is it my intention to limit myself to any particular rubber compound, with the exception that the content of the vulcanizing medium must be so low as to approximate 1% of the rubber content of the batch.
It is also essential to the invention that the packing gasket shall be applied to the shell while the material thereof is plastic, and that the shell with its contained gasket shall be subjected to the required vulcanizing temperature.
Having described the invention, what I claim as new and desire to have protected by Letters Patent, is
1. A method of making bottle caps embodying therein the extrusion in tubular form of a compound containing rubber, a filler, and a low content of a vulcanizing agent, the separation of the tube, in its unvulcanized condition, into rings, the delivery of such rings to a skirted metallic shell Within and adjacent the skirt thereof, and the sub vulcanizing agent, the separation of the ex- 4 truded compound into gasket sections of the desired thickness, the deposit of a section while in an unvulcanized condition in a. skirted metallic shell, and the subjection of the metallic shell and its contained gasket section to a vulcanizing temperature, whereby said gasket will be bonded to the metal shell and will be simultaneously semi-vulcanized.
3. A method of making bottle caps embodying therein the extrusion in tubular form of a compound containing rubber, a filler, a low content of a vulcanizing agent, and an organic accelerator, the separation of the tube, in its unvulcanized condition, into rings, the delivery of such rings to a skirted metallic shell within and adjacent the skirt thereof, and the subjection of the metallic shell and its contained ring to a vulcanizing temperature, whereby said ring will be bonded to the metal shell and will be simultaneously semi-vulcanized.
4. A method of making bottle caps embodying therein the extrusion in a form to enter a bottle cap of a compound containing rubber, a filler, approximately 1% of a vulcanizing agent, and an organic accelerator, the separation of the extruded compound into gasket sections of the desired thickness, the deposit of a section while in an nnvul canized condition in a skirted metallic shell, and the subjection of the metallic shell and its contained gasket section to a vulcanizin temperature, whereby said gasket will be bonded to the metal shell and will be simultaneously semi-vulcanized.
In witness whereof I have hereunto aflixed my signature.
CECIL J. PARKER.