US3211316A

US3211316A - Container closure

Info

Publication number: US3211316A
Application number: US275673A
Authority: US
Inventors: Albert M Fischer
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1958-09-12
Filing date: 1963-04-25
Publication date: 1965-10-12
Anticipated expiration: 1982-10-12

Description

Oct. 12, 1965 A. M. FISCHER 3,211,316

CONTAINER CLOSURE Original Filed Sept. 12, 1958 5 Sheets-Sheet l 23 J0 JZ .J3 jg ATTORNEY Oct. l2, 1965 A. M. FISCHER 3,211,316

CONTAINER CLOSURE Original Filed Sept. l2, 1958 y 3 Sheets-Sheet 2 21e r 2j V w llIIllIllIlIl/III/IllI//llIIIll/lIlIIll/ll A Y M15 Ja 245( ALBERT ER ab 3' 13j) #XM-w ATTORNEY Oct. 12, 1965 A. M. FISCHER CONTAINER CLOSURE 5 Sheets-Sheet 3 Original Filed Sept. 12. 1958 y RH OC M mw M EF. T V T mM A T R E B A United States Patent 3,211,316 y yCONTAINER CLOSURE Albert M. Fischer, Dowa'giac, Mich., assighor, by mesne assignments, to Union Carbide Corporation, a corpog ration 'of New York p p Y Y Original application Sept. 12, 195,8, Ser. No. 760,692, now Patent No. 3,087,639, dated Apr. 30, 1963. Divided and this application Apr. 25, 1963, Ser. No. 275,673

3 Claims. (Cl. 21S- 39) ThisV application is a division of application Serial No. 760,692, `tiled September l2, 1958, and now U.S. Patent 3,087,639.

The present invention relates, in general, to closures such as crown closures, metallic cap closures, screw-on closures and the like, and, in particular, to a new and improved cap closure and plastic sealing means therefor, which can be assembled with substantially conventional crown assembling machines.

,Bottle caps, also referred to as crown closures, generally comprise a metallic crown cap, preferably formed of cold rolled tin plate, having a corrugated rim or skirt within which a sealing means is placed; the latter usually being cemented or otherwise secured to the crown cap. Of recent innovation, in the crown 'closure industry, has been the use of sealing means made of plastic, such as polyethylene. Further development of plastic sealing means to further increase their usefulness as crown cap sealing means, brought about the provision of marginal rings or rims and flex-rings as well a's inner sealing rings, as for example, the plastic sealing means disclosed and claimed in the U.S. Patent No. 2,829,790 to Alfons Isele- Aregger issued April 8, 1958 and entitled Bottle Closures, and the application for U.S. patent of Alfons Isele-Aregger, Serial No. 559,445, filed January 16, 1956, entitled Sealing Disc for Metallic Cap Closures, Crown Closures and the Like, issued on August 25, 1959 as U.S. Patent 2,901,139, to which reference is made for a full and complete description thereof.

However, some embodiments of prior art plastic sealing means could not too successfully 4be used in conventional crown assembling machines because of their tendency to nest with each other i.e., the 'interlocking of the respective annular marginal rims and seal rings when attacked in the seal feed tube in such machines. When such nesting took place, the machines shuttle or ejector mechanism for ejecting would cause tearing of the seals and/ orfwould insert more than one seal in vany one crown cap. On the other hand, those embodiments of Aprior art sealing means which did work reasonably successfully in crown assembling machines did not have good sealing qualities in use-very undesirable features.

Still a-nother disadvantage in existing plastic sealing meansfor crown caps is that they could not be positively retained in the crown cap prior to the capping ope'ration, which was due chiefly to 4the insuicient frictional retention characteristic between the marginal seal rim and the crown cap.

Accordingly, it is a general object of my invention to overcome the `general disadvantages found in vprior art closures.

Briefly, myiinvention comprises a sealing means of relatively thin material, such as polyethylene `or other suitable plastic material, having an 4outer marginal peripheral ring or rim, an inner relatively thin flex-ring, and one or more inner sealing rings, which surrounds a 'relatively thin diaphragm. In -some embodiments of my invention, the outer marginal ring -is thicker 'in median plan than the Ainner sealing rings, is preferably provided with a substantially flat top and bottom so as to form a substantially trapezoidal configuration, and the inner seal '3,211,316 Patented Oct. 12, 1965 ICC Ving rings are preferably provided with sides of al certain angularity with respect to each other. These features function as an anti-nesting measure in the crown assembly machines as will be understood hereinafter, and the radially outer periphery of the marginal ring is preferably pointed or provided with a sharpv corner in median plan and is somewhat larger than the diameter of the inside of the metallic crown cap, whereby the marginal ring together with the dex-ring will cooperate to be frictionally retained in the crown cap as will be understood hereinafter. g

In other embodiments of my invention, wherein the outer marginal ringis omitted and the flex-ring is retained, the outer seal ring is thicker than the inner seal ring or rings and provided with substantially dat surfaces to facilitate stacking as an anti-nesting 4measure in crown assembly machines as will be understood, and in all the embodiments of my invention, the outer marginal seal ing ring andthe inner sealing ring or rings are preferably symmetrical in median plan so as to facilitate their sorting in the hopper of conventional crown assembly machines in which the sealing means are normally placed.

With my new and improved sealing means, I( have found that I can use a minimum of plastic Ymaterial and a minimum of metal in the crown cap itself by use of shorter skirts on the crown cap and by using thinner gauge metal. I have found also that with my sealing means, aluminum may be used as well as conventional tin plate for crown caps.

As to the crown cap, where desirable or necessary in cert-ain applications and as an added feature to my present invention, I provide my crown cap with a retaining means for positively retaining the sealing means therein. This retaining means for my crown cap comprises a plurality of inwardly extending projections, or an inwardly extending peripheral band, which will cooperate with the radially outer periphery of the marginal ring or the flex-ring, as the case may be, of my sealing means to positively retain the sealing means within the crown cap. In one embodiment these projections or the band are formed of a special friction producing lacquer.

In certain other applications where the projections or bands are not desired, I have provided still another Vmanner of retaining `the sealing means in the crown capjby the provision of means such as the addition of suitable quantities of bentonite, magnesium silicate, etc., to the conventional lacquer used to coat the inside of the crown cap. The purpose ofthe addition of this material -is to increase the Africtional Yqualities of the coating, thus assuring an improved frictional lretention ofthe seal in the crown cap.

Another important feature of my invention is the provision of a new and improved 'shuttle mechanism and a new and `improved seal feed tube for crown assembly machines. The working edge of my shuttle mechanism has a configuration which conforms with the particular configuration of the periphery of my sealing means and I have improved the seal feed 'tube of conventional crown assembling machines to cooperate with :the stacking of the plastic sealing means, as will be explained in detail hereinafter. y

Thus, a more particular object of -my invention is 'to provide a new and improved plastic sealing means for crown closures and the like.

Still `another object of my invention is to `provide a new and improved plastic sealing means for crown closures and the like useable in conventional crown assembling machines now in general `use in the crown closure producing industry, but having my new and improved seal feed tube and shuttle ejector mechanism.

Still another object of my invention is to provide a new and improved plastic sealing means having improved frictional retention characteristics in the crown cap.

Another object of my invention is a new and improved metallic crown cap which will cooperate with my new and improved plastic sealing means to retain the plastic sealing means in the crown cap prior to the capping operation.

Still another object of my invention is to provide a new and improved plastic sealing means and a new and improved metallic crown which can be manufactured with a minimum of plastic material and which will provide a means of reducing the metal required of the crown cap when made of conventional tin plate, or the use of aluminum for the crown caps.

Still another and further object of my invention is the provision of a new and improved seal feed tube and a new and improved shuttle mechanism in conventional crown cap assembling machines which will cooperate with my new and improved plastic sealing means.

Other and more particular objects of my invention will be apparent to those skilled in the art from the following description and drawings forming a part hereof and wherein:

FIG. 1 is a top plan view of a plastic sealing means, constructed in accordance with the teachings of my invention, having an outer annular marginal ring and inner annular seal rings of a vertical thickness less than the vertical thickness of the marginal ring;

FIG. 2 is a vertical, cross-sectional view of the plastic sealing means shown in FIG. l;

FIG. 3 is a vertical, crosssectional view of the sealing means shown in FIGS. l and 2 and inserted in a crown cap, illustrating how my sealing means cooperates with a known form of an indentation for holding the sealing means positively in the caps, and resting on the top of a bottle lip prior to the crowning operation;

FIG. 4 is a vertical, cross-sectional view of the sealing means, crown cap and bottle lip, shown in FIG. 3, after the crowning operation;

FIG. 5 is a partial, vertical, cross-sectional view of a plastic sealing means, constructed in accordance with my invention, having an outer annular marginal ring and inner annular rings of various vertical thickness but less than the vertical thickness of the marginal ring;

FIG. 6 is a partial, vertical, cross-sectional View of plastic sealing means of a type similar to that shown in FIG. 5 but showing the outer or marginal ring with a flat top and bottom portion similar to the marginal ring of FIG. 2;

FIG. 7 is a partial, vertical, cross-sectional view of a plastic sealing means similar to that shown in FIG. 5 except that the inner annular sealing rings are vertically narrower than the outer annular marginal ring but of the same vertical thickness as to each other, similar to the sealing means of FIG. 2;

FIG. 8 is a partial, vertical, cross-sectional view of my plastic sealing means having only one annular sealing ring of the same vertical thickness as the outer marginal ring;

FIG. 9 is a partial, cross-sectional View of my plastic sealing means, similar to that shown in FIG. 8 except that the outer marginal ring has the same vertical thickness as the inner sealing ring and is provided with a flat top and bottom portion;

FIG. 10 is a partial, cross-sectional view of my plastic sealing means, similar to that shown in FIG. 8, except that the inner sealing ring has a vertical thickness less than the vertical thickness of the marginal ring;

FIG. 11 is a partial, vertical, cross-sectional view of my plastic sealing means, similar to the sealing means shown in FIG. 10, except that the marginal ring is provided with a dat top and bottom portion;

FIG. 12 is a partial, vertical, cross-sectional view of another form of marginal ring for my sealing means;

FIG. 13 is a partial, vertical, cross-sectional view of my plastic sealing means in which the space between the outer marginal ring with a at top and bottom and the inner sealing rings is reduced to a minimum;

FIG. 14 is a partial, vertical, cross-sectional view of a conventional crown assembly machine ejector with my plastic sealing means positioned in the cylinder of the crown assembly machine;

FIG. 15 is a partial, vertical, cross-sectional view of another form of my plastic sealing means wherein the marginal ring is omitted, the ex-ring extended, and the radially outer sealing ring is provided with flats to prevent nesting;

FIG. 16 is a vertical, cross-sectional view of one embodiment of a crown cap, constructed in accordance with the teachings of my invention, showing to advantage a peripheral rim formed in the metal of the cap to positively hold the sealing means in the cap prior to the crowning operation;

FIG. 17 is a vertical, cross-sectional view of still another embodiment of my crown cap having another type of rim or band formed of improved lacquer for positively retaining the sealing means in the crown cap;

FIG. 18 is a vertical, cross-sectional view of still another embodiment of a crown cap showing to advantage another form of projections or dots formed of improved lacquer for retaining the sealing means positively in the crown cap;

FIG. 19 is a partial, enlarged, plan view of a blank from which the crown caps are blanked in a conventional manner and illustrating to advantage the means of forming the lacquer retaining rim or band for the crown cap as shown in FIG. 17;

FIG. 2O is a partial, enlarged, plan view of a blank, such as illustrated in FIG. 19, but showing to advantage the lacquer retaining projections or dots for the crown cap as shown in FIG. 18; and

FIG. 21 is a vertical, cross-sectional view of the elements of the crown assembly machine for suitably adhering the sealing means to the crown cap in applications -where the use of adhesive is thought necessary.

Turning now to the drawings and in particular to the FIGS. 1 through 4, I have illustrated a plastic sealing means, indicated in its entirety as 10, constructed in accordance with the teachings of my invention in its preferred form which comprises a relatively thin imperforate disc having a relatively thin diaphragm 11 in its central portion, adjoined by `or encircled by one or more annular seal rings 12, 13 (two shown) each of which comprises axially or vertically extending ribs of triangular crosssection terminating in not smaller than a right angle and preferably an obtuse angle defined by

sides

14, 15 and 16, 17, respectively, with the

sides

15 and 17, facing the outer periphery of the sealing means, being provided with a Hatter incline than

sides

14 and 16 for a purpose hereafter to be described. Sealing rings 12 and 13 are surrounded on their peripherally outer end with a relatively thin, flexible, membrane-like area or flex-ring 18, and which is provided to give the sealing means 10l the necessary flexibility in this area for the purpose hereinafter to be described.

Adjoining the flex-ring 18 and encircled thereby, is an outer marginal ring 20, which forms the outer periphery of the sealing means and in its preferred form has a substantially flat top and the

bottom side

21, 22. It is to be noted that my sealing means in its preferred form is symmetrical or substantially symmetrical in cross-section (or, otherwise stated, is symmetrical or substantially symmetrical in median plan), and that the vertical thickness of the marginal ring 20 is greater than :the vertical thickness yof the seal rings 12, 13 to be advantageous for a crown assembling machine.

It can be appreciated that with the sealing means symmetrical in cross-section, both sides are useable and, when a plurality of these sealing means are disposed in a hopper for eventualA use by the crown assembly machine, any sorting that will otherwise be required if there was non-symmetry, has been eliminated.

l While I have shown the marginal rin-g 20 as having a flat top and bottom with the sides, such as 21a and 2111, actually forming angles therewith, as for example at 21C, with the'anglerZlic being delined by

sides

21 and 21d (FIG. 12) whereby `side 21d is merely a curve with a suitable radius Ato blend the substantially ilat top with the sides; the important point being that the top and bottom sides are `substantially fiat so that the top will cooperate in a stacking manner with the bottom side of a like sealing means, such as illustrated in FIG. 14.

The outside diameter of the sealing means is preferred to be slightly larger (at least 0.005 inch) than the standard inside diameterof a crown such as 23 so that it permits the seaLwhen pressed into the crown 23 during the crown assembling operatiomto align itself, more or less, with the contourrof the inside of the crown as more fully illustrated in FIG. 3. In this position the Hex-ring 1,8 exercises a radial force against the inside of the crown skirt due Vto its tendency to straighten out, which force is transmitted to the louter edge 24 of the marginal ring 20, which presses against the crown skirt thereby establishing the frictional retention of the sealing means 10 in ,the crown 23.

This tendency of the seal 10 and especially the Hex-ring 18 to straighten out has another advantage in the crown assembly operation. It is a well known fact that very close when produced by injection molding or other suitable methods, yet on the other hand, the crowns or caps such as 23 (see FIGS. 3 and ,4) due to the wear of the blanking dies, may have slightly varying inside diameters deviating from standard. l

By, way of explanation of the operation of my seal means, the plastic material selected must meet certain standards of the beverage, food and drug industries and it also must have required physical properties i.e., suincient tensile strength, elasticity, resiliency and a minimum of cold now'. v While any suitable plastic materials may be employed, I` prefer a low density polyethylene wherein, due to the `particular configuration of my sealing means, the resiliency of the polyethylene is -fully utilized. While plastic materials, such as a low density polyethylene are not `readily resilient and compressible in items having substantial Icross-sectional areas, it has been found that narrower cross-sectional areas, such as employed in the sealing means of my invention, show remarkable resiliency as demonstrated by their compressibility, .provided their molecular structure is not overstrained. Due to this resiliency, the sealing means is able to compensate for imperfections in the bottle lip and also forthe difference inthe coefficients of thermal expansion between glass a'nd steel as in the case of crowned bottles. As outlined herein, the degree of resiliency, and therefore, the ability to effect 'a gas-tight seal, is directly related to the shape of the cross-section of the lri'ngs or rims of seals.

As illustrated in FIG. 4, the sealing veffect is obtained by compressing the annular sealing rings 12, 13 and the marginal ring 20, of theV preferred form of my invention, illustrated in FIG. 2, when the crown cap 23 is pressed on la bottle lip 25 of bottle 26 and the crown skirt 27 is crimped onto a bottle locking ring 28. In this crowning operation,` the sealing

ribs

12, 13 are compressed and align themselves with the ,contour of the bottle lip 25, and, as usual, in this type crowning operation, the greatest pressureper square inch is appli-edrin theV areav30 of ,the bottlelip 25, however, with the configuration of my marginal seal ring 20 it can be forced into the 'angular space 30a without overstrain in the molecular structure of the plastic material and thus the resiliency of this section is also retained. From the foregoing description it can be seen that the marginal seal ring of my invention has two functions namely: V(l) to retain the seal in the crown vcap before crowning, and (2) to act as an additional sealing area; this latter feature being very important in the function of the preferred embodiments of my invention, for example, Where bottle imperfections are found. Too, t-he pressure necessary to effect a tight seal is not high enough to overstrain the molecular structure of` other parts of the sealing means participating in the sealing action and, therefore, all parts of the sealing means retain their resiliency resulting in a gas-tight closure. I have found, under exhaustiveV tests on a crown closure employing my invention, that the sealing ability was not impaired when repeated temperature changes ranging from 33 F. to 150 F. were produced during an extended test period of Iseveral weeks. These tests also produced pressures which were quite high, viz., in a test withrfive (5 volumes of gas, at an elevated temperature of F., a pressure of lbs. per square inch is produced and it was found 'out that, with the i sealing means, such as described herein, pressures of 200 lbs. per square inch were retained.

By way of explanation for the results of the tests on my sealing means, reference is made to FIG. 4 where it can be seen that the internal bottle pressure indicated as P in a bottle 26', tends to lift the crown cap 23. However, due to the configuration of the sealing means 1,0, the pressure does not act, as in the case of a cork seal or other sealing means, over the entire area of the sealing means, but only over the area defined or circumscribed by the inside diameter of the innermost sealing ring 12, which in one specific embodiment of my invention is about 0.70 inch. Consequently, an internal bottle pressure of 315 lbs. per square inch acting against such a seal, equals SL30 lbs. It can be seen that if my sealing means did not have the annular sealing ring 12 and would depend on the marginal seal ring 2t) only, the pressure acting against the crown would be 118.80 lbs. which is based on the seal outside diameter of 1.060 inches.

The construction and operation of myseali'ng lmeans in the crown cap as pressed on the bottle 26 has still other additional advantages. It is well known that a low density polyethylene is permeated by water vapors, CO2, etc., and, therefore, can normally onlybe used under special conditions for the sealing of a vacuum or pressure packed liquids containing CO2 or other gases. According to my invention, a vseal made of low density polyethylene is rendered effectively impermeable to gases when the sealing rings are compressed in the sealing area as in FIG. 4. In this crowning operation, there is created a relatively high specific pressure in the narrow contact zones formed between the bottle lip 25 and the

seal ring

12, 13, the marginal ring 20 on V'one side and the crown cap 23 on the other.

While I have explained the operation of my invention in connection with my 4preferred form of sealing means, as illustrated in FIG. 2 of the drawings, wherein the sealing rings 12 and 13 each have'the obtuse angle a, formed by

sides

14, 15 and 16, 17 and have explained the operation thereof in connection with the marginal lsealing ring 20 of greater vertical or transverse thickness, it can be appreciated from a 'study of FIG. 13, that vdifferent angles on the sealing rings may be employed. Furthermore, it is not necessary that two such sealing rings as 12 and 13 be employed as illustrated in FIGS. 8, Y9 and 1'0 nor is it necessary that the sealing rings have a thickness less than the marginal ring, as illustrated in FIGS. `8 and A9; the important point is that one of the sealing rings or the marginal ring should be thicker and preferably with a flat top and bottom side so as to permit stacking ofthe seals in a seal feed tube without nesting. Furthermore, in certain other applications, thefflex-ring 18 may be narrowed 'down toa minimum, as illustrated in FIG. 13,'or the marginal =ring itself maybe eliminated as illustrated in FIG. 15 leaving only an extended and modified flexring with

flat sides

13a and 13b being provided on the relative thick seal ring 13. Also, while it is preferred that the marginal ring be trapezoidal and have flat top and bottom surfaces, such as illustrated in FIGS. 2, 6, 9, 11, 12 and 13 for the prevention of nesting in a crown assembling machine, the marginal ring or outer seal ring, as the case may be, may be angular at its top and bottom as illustrated in FIGS. 5, 7, 8 and 10 where crown assembling is carried out in machines where stacking is not ernployed. It will be clearly recognized from a study of FIG. 14, that the

flat surfaces

21 and 22 of the preferred form of my invention, as well as the flat surfaces of the other forms as illustrated in FIGS. 6, 9, 11, 12 and 13 facilitate the stacking of the sealing means and prevent nesting in a conventional crown assembling machine utilizing stacking, schematically illustrated in part in FIG. 14.

It can be appreciated that with the large number of crown sealing means being used, any saving of material is important. To accomplish this saving in the sealing means itself, the sides of the marginal ring, such as 21d and 21e, are curved or concave as illustrated in FIG. 12, or the Hex-ring itself is pointed or concave as illustrated at 18a, 18h in FIG. 15. This feature has the additional advantage of increased retentivity characteristics in the crown cap as can be appreciated from a study of FIG. 3. As to the crown cap itself, the saving is accomplished by the reduction in the thickness of my sealing means as compressed (see FIG. 4) as compared to conventional cork seals or other plastic seals so that the distance from the top of the cap to the locking ring 27 is reduced. Also, I have found with my seal, that thinner gage metal may be used because of the reduced internal bottle pressure acting against the reduced area on my seal and crown. This reduction in area also permits the use of aluminum instead of tin-plate for the cap.

More specifically, in connection with the operation of my sealing means, in production runs it has been eX- perienced that plastic sealing means with annular seal rings tend to nest when seals are stacked in the feed tube of conventional crown assembling machines, i.e., the marginal rims and sealing rings tend to overlap. This results in tearing of the sealing means by a shuttle or ejector and/or causes the shuttle to insert more than one seal into any one crown. By the particular configuration of my invention, such nesting is overcome due particularly to the preferred form of marginal seal rings, as illustrated in FIGS. 2, 6, 9, 11, 12 and 13, where one seal ring is thicker than the other as the case may be, and terminates on both sides by flats, such as 21 and 22, or 13a, 13b. As a further aid to prevent nesting it is preferred that the feed tube, indicated schematically in its entirety in FIG. 14 as 31, and cylindrical section 32 thereof, conventionally designed for feeding cork seals (and customarily has a larger inside diameter than the outside diameter of plastic sealing means), be provided with an intermediate tapering section 33, which connects the large section 32 to a smaller cylindrical section 34 of the feed tube. The section 34, being of a smaller inner diameter than the inner diameter of the tube 32, is only slightly larger, and preferably not more than .010 inch larger, than the outside diameter of the seal. In this manner the sealing means line up and stack automatically, as illustrated in this FIG. 14, and the entire assembly is connected to a vibrator (not shown).

In the conventional crown assembling machine, there is provided a shuttle 35 or ejector, in connection to a source of motivating power (not shown) whereby the shuttle is reciprocated to the right and to the left, as illustrated in FIG. 14, in and out of

apertures

36 and 37 in the cylinder 34 whereby the shuttle 35 may eject one sealing means at a time. I have improved the conventional crowning assembly machines still further, by providing the shuttle 35 with a V-shaped portion 38 and a chamfer 40. The V-shaped section 38 conforms, as can be seen, to the outer periphery of the marginal ring to aid in centering the periphery 24 in the ejector and guiding it out of the feed tube and the chamfer 40 prevents its catching or the like with the next sealing means above and in line to be ejected. I have found also in connection with this operation that by providing the sealing rings with the llattest inclined surfaces such as 15 and 17, facing outwardly, the ejection mechanism 35 functions more successfully.

As hereinbefore mentioned, it is highly desirable that the plastic sealing means be retained in the crown cap prior to the crowning operation. To augment this, I have provided my sealing means with a pointed or narrow rimmed portion 24 or 24', for the purpose of increasing the specific pressure of the seal against the crown skirt which together with the flex-ring provides the required frictional retentivity to retain the seal in the crown cap. However, in certain applications, it is desirable to insure that the plastic sealing means will remain positively in the crown cap prior to the crowning operation and I have found that my sealing means cooperates exceedingly well with dimples or indentations 41, (see FIGS. 3 and 4). These indentations are usually spaced equidistant about the cap and formed in the metal of the cap slightly below the curved portion 42 and a sufficient distance below the top of the crown cap to permit the sealing means to assume a curvature as illustrated in FIG. 3. The sealing means 10, being oversize and with a pointed rim 24 or 24', will snap over the dimples in the cap when so inserted and brace itself against the top portion of the dimples 41 and thereby be positively retained in the crown cap.

As hereinbefore mentioned, one embodiment of my crown cap comprises a cap 23 having an improved sealing retaining means therein. Thus, as illustrated in FIG. 16, the dimples 41 may be replaced by a continuous inward protruding rim 43, formed in the metal of the cap itself. The marginal rim 43 will have the same function and operation as the dimples 41 and in a crown may be located in substantially the same location with respect to the top as the dimples.

As another feature of my invention, the known dimples 41, such as illustrated in FIG. 3, or the improved rim 43, such as illustrated in FIG. 16, may be replaced with a plurality of small projections or dots 44 formed of a special lacquer in such a manner as illustrated in FIG. 18 or by a perpheral rim 45, such as illustrated in FIG. 17. The formation of these lacquer dots and rims will be explained in more detail hereinafter but it is sufficient to say that the lacquer dots 44 and lacquer rim 45 will function to retain the seals in the crown cap 23.

In accordance with conventional practice the tinplate on the side, which will become the inside of the nished crown cap is coated with a lacquer composed of an oleoresinous type of a drying oil and a varnish resin together with a dryer and gold or other color material. This lacquer dries with a glossy surface and usually provides a minimum of friction. As heretofore mentioned, to increase the frictional characteristic of the conventional lacquer and thereby the retentivity of the seal in the crown, I add a small amount of inert material (3%-5%) such as bentonite, magnesium silicate, etc., to the lacquer for the first coating. If preferred, means may be provided to produce brush marks or a texture to the coating, so as to roughen the surface covering the skirt, to improve the frictional retentivity of the crown still further.

Turning now to FIG. 19 wherein I have illustrated a flat sheet of tin-plate 46 used in the conventional crown making operation, after the conventional lacquer has been applied to the tin-plate by 4the coating machine and has dried.

This improved lacquer, as described above and indicated in FIGS. 17, 18 and 19 may be applied either as concentric rings 45 as illustrated or as plurality of dots 44, which are relatively thin, yet in the finished product as illustrated in FIGS. 17 and 18 provide sufficient frictional surface to considerably improve the retention of the sealing means therein. These rings 45 or dots 44 are applied after the first coating of lacquer has dried and can be carried out by running the tin plate through a second coating machine or may be applied after the blanking out of the crown by a spray process or brushing process or any other `suitable means.

Where it is not necessary or desirable to provide dots or rims as illustrated, -this same modified lacquer may be applied as a rst coating the same as present practice of conventional lacquer by the conventional machine and, if preferred, an attachment may be provided to produce brush marks or a texture to the coating to improve the frictional retentiveness of the crown still further.

It may be desirable, where thought to be necessary, that a liquid adhesive be applied into the formed crown to retain the seal. This adhesive may comprise a blend of synthetic rubbers and modifying resinous material dissolved in a volatile solvent such as hexane. This adhesive could be applied to the crown inside thereof in the crown assemblying process in a customary manner with a rotary applicator or any other suitable means as is conventional before the seal is inserted. Thus, as in conventional crown assembly operations, when the crown is heated to a temperature of about 230 F. the `solvent will be evaporated. In Vsuch an operation cam-controlled plungers of the conventional crown .assembly machine such as illustrated at 50, but having a reduced end portion 51 may be used to press the center membrane or diaphragm of the sealing means against the crown top heated by contact with the heated table 52 bringing about a thermo-plastically produced deformation and alignment `of the center seal diaphragm with the crown top thereby aiding the spreading the adhesive between the `seal and the crown and consequently accelerating the evaporation of the solvent and resulting in a secure bond, The reduced end portion 51 -of the plunger accommodates the sealing rings and/ or sealing marginal rim as can be appreciated.

Where herein the various parts of my invention have been referred to as located in a right -or left or an upper or lower or an .inward or outward position, it will be understod that this is done solely for the purpose of facilitating description and that such references relate only to the relative positions of the parts as shown in the drawings.

Also, it is to be understood 4that many changes and modifications may be made without departing from the scope or spirit of the invention and the invention is dened and comprehended solely by the appended claims which should be construed as broadly as the prior art will permit.

I claim:

1. A new and improved crown cap for pressure containers and the like comprising a shell having an internally domed circular portion with a smooth internal surface bounded by a top corner radius portion of smooth curvature and having a peripheral skirt portion joined to said top corner radius and adapted for engagement with a locking ring of the container, the improvement comprising means deiining an inwardly extending peripheral band yof lacquer formed between said skirt portion and said corner radius portion, said band of lacquer engaging the edge of a plastic closure sealing means for positive retention of said sealing means in said crown cap prior to the crown capping operation.

2. A new and improved crown cap for pressure containers and the like comprising a shell having an internally domed circular portion with a smooth internal surface bounded by a top corner radius portion of smooth curvature and having a peripheral skirt portion joined to said top corner radius and adapted for engagement with a locking ring of the container, the improvement comprising means defining an inwardly extending frictional retentive means formed by lacquer between said skirt portion and said corner radius portion and, said retentive means engaging the edge of a plastic closure sealing means for frictional retention of said `sealing means in said crown cap prior to the crown capping operation.

3. A new and improved crown cap for pressure containers and the like comprising a shell having an internally domed circular portion with a smooth internal surface bounded by a top corner radius portion of smooth curvature and having a peripheral skirt portion joined to said top corner radius and adapted for engagement with a locking ring of the container, the improvement comprising means dening a plurality of inwardly extending dots of lacquer formed between said skirt portion and said corner radius portion, said dots of lacquer engaging the edge of a plastic closure sealing means for positive retention of said sealing means in said crown cap prior to the crown capping operation.

References Cited by the Examiner UNITED STATES PATENTS 1,512,347 10/24 Lorenz 215-40 2,092,192 9/37 Von Till 21S-43 2,858,659 11/58 West 53-287 2,904,837 9/59 Crabbe 21S-43 2,948,096 8/ 60 Anderson 53-287 3,033,407 5/62 Isele Aregger 215-39 3,089,604 5/63 Golde et al 215-39 JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

Claims

1. A NEW AND IMPROVED CROWN CAP FOR PRESSURE CONTAINERS AND THE LIKE COMPRISING A SHELL HAVING AN INTERNALLY DOMED CIRCULAR PORTION WITH A SMOOTH INTERNAL SURFACE BOUNDED BY A STOP CORNER RADIUS PORTION OF SMOOTH CURVATURE AND HAVING A PERIPHERAL SKIRT PORTION JOINED TO SAID TOP CORNER RADIUS AND ADAPTED FOR ENGAGEMENT WITH A LOCKING RING OF THE CONTAINER, THE IMPROVEMENT COMPRISING MEANS DEFINING AN INWARDLY EXTENDING PERIPHERAL