US 2242256 A
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y 20 1941- c. E. McMANus I 2,242,256
Filed July 17, 1935 v 2 Sheets-Sheet 1 Em Mp MayZO, 1941 Filed July 17, 1935 C. E. MMANUS CAP 2 Sheets-Sheet 2 2 'IIIIIIIIIIIIIIIIJIIIIZI! jygml those of the type which includes. r
plied to the caps 1 seal for both pressure as water and moisture vapor.
' Patented May 20, 1941 car rles E. McManus, Spring Lake, N. 3., .assignor J to Crown Cork 8: Seal Company,
Md.,'a corporation of New York Application July 17, 1935 ,'Seria l No. 31,902 Claim (CL 215-39) caps and particularly metal shell, a cushion liner therefor and a cen spot or overall facing of resilient andprotective material.
li'he invention involves as an essential feature the use asa facing material, particularly as a center spot, of chlorinated rubber in the form of a relatively transparent film, and more particularly the application .of the same to the cushion liner in such a way as to provide a firm and relatively permanent adhesion. An important feature of the invention is the use of the film-like chlorinated rubber in strip form having combined therewith a material of the character hereinafter described, having sufficient body to impart to the strip the characteristics necessary for use in the conventional spotting methods. In other words, I have found that, although a My'invention relates to chlorinated rubber film or strip is not suitable alone for use as a spotting material, it may be combined with other materials, in the manner hereinafter described, to impart to the same the characteristics necessary for use in the methods heretofore developed for center spotting caps, particularly caps of the crown type. As wi be appreciated, these considerations are vital from the practical standpoint. For example, in order for the chlorinated rubber facing to be successful, it must be free, from any possibility of slipping or moving with relation to the cushion liner or of separating therefrom under condi: tions of use. Furthermore, and of equal importance, it is necessarythat the chlorinated rubber facing material be capable of being fed and apby automatic machinery.
The present invention therefore also comprehends a strip facing material including chlorinated rubber, and a method of making the same' as well as a method and means of adhering the facing to a cap. Thus, I am able to produce caps using a center spot or overall facing of chlorinated rubber which will act as a universal and non-pressure substances, namely, foods, beverages, medicines, etc.
I have found that a cap constructed in accordance with the present invention does not impart odor or taste to the contents of a vessel being sealed, and moreover, the facing film is impermeable to liquids and gases, alkali, acid and oil resistant, and resistant to most solvents as well I Also, the facin film is self-sealing and is possessed of a stretch characteristic permitting conformity to the contour of a sealing lip of a bottle or other container, e. g., inthe case of crown caps. The cap.
having a facing layer of produced in accordance with this invention, also discloses under test reduced evaporative losses, and is comparable with rubber sealing gaskets, and the seal does not deteriorate through a. wide range of climatic conditions. I
It is an important feature of my invention that the facing film of chlorinated ditions of use, does not move or lose its centered position with relation to the cushion liner to which it is affixed nor does it separate or loosen therefrom. Hence, I have found that in accordance with this invention not only resistant to the. action of the contents which are sealed, but over long periods of time, leakage losses are reduced to a negligible minimum. In this connection, the adherence of the facing film to the cushion liner is such that notwithstanding the cap is used in sealing hot bodies or under pasteurization and sterilization conditions, the centered spot or overall facing does not undergo any substantial change of position or of adherence such as would reduce the sealing value of the cap..
The chlorinated rubber facing film may be adhered directly to the cushion liner material, since it is capable of being rendered tacky and adherent by heat and this is satisfactory in some cases.
.The facing film, however, is preferably reinforced for use in cap spotting machines by a .of chlorinated rubber, The spot will be substantially flush with the cushion liner and not be objectionably projected thereabove, which latter condition particularly in the case of containers having a narrow sealing lip is to be avoided. Hence, by reason of a strong thin' strip spotting material, there does not take place any substandraw the same-away from the sealing lip of a container or objectionably stretch or release it from the cushion liner. .Moreover, not only is the facing material of such thinness as to prevent disruption of the seal, but the chlorinated rubber itself is in the form of a very thin film, and
hlorinated rubber andthe best quality of pure rubber, under coninvention 1 am able to proexerts a self-sealing eil'ect -and has a stretch suitable shades or colors may be imparted to the facing. Thus, I may apply a film of paint or pigmentizing agent to the undersurface of the facing or include such coloring material with the adhesive by which the facing film is adhered to the cushion liner or backing.
The liner material is capable of being produced in rolls suitable for use in the usual cap spotting machines and is durable in that it does not deteriorate in storage. In fact, the liner material of the present invention has along life and when used in caps, will effectively seal the contents of a container with which the cap is associated over long periods of time without leakage or spoilage of the substances sealed.
Various other advantages are inherent in the invention, which will be described in detail in the following specification.
Referring to the drawings:
Figure 1 is a bottom plan view of a crown cap having a cushion liner and a facing layer of chlorinated rubber, a portion of the facing being broken away to show a backing layer of adhesive;
Figure 2 is a section through the cap of Figure 1;
Figure 3 is a detailed view of the liner material employed in connection with Figures 1 and 2 and consisting of a layer of chlorinated rubber and backing a layer of adhesive;
Figure 4 is a sectional view similar to Figure 2 but showing a different type of laminated facing, i. e., a facing material constructed in accordance with Figure 5.
Figure 5 is a detailed view showing a built-up facing layer utilized in connection with Figure 4 wherein the facing of chlorinated rubber is adhesively united to a foil backing and the latter adhesively united to the cushion liner of the cap.
Figure 6 is a sectional view similar to Figure 4 and showing a different type of facing material, for example, as shown in Figure 7;
Figure 7 is a detailed view showing a built-up facing layer wherein the rubber layer is adhesively united to a backing layer of paper and the latter adhesively united to the cushion liner as shown in Figure 6;
Figure 8 is a sectional view showing an overall facing;
Figure 9 is a sectional view showing the chlorinated rubber facing adhered to the cushion liner without another adhesive;
Figure 10 is a sectional view showing the facing adhered to a backing without use of another adhesive;
Figure 11 is a view showing the chlorinated rubber facing provided with a colored coating on its undersurface;
Figure 12 is a sectional view of a film of adhesive which is suitably colored;
Figure 13 is a sectional view of a layer of .chlorinatw-rubber which is suitably colored;
Figure 14 is a sectional view of a paper layer provided with a coating to render the same nonadsorptive.
While I have illustrated in Figures 1 to 9 a crown cap, it will be appreciated that the invention is equally operable with caps of the lug, pull off, screw or divided thread type as well as the type illustrated in the patent to Booth, No.
1,956,217, April 24, 1934, and in fact, with all types of metal. Moreover, while the drawings show the facing embodied as acenter s, at, this is for purposes of illustration only in that the invention is equally useful as an overall facing, i. e., facings which are coextensive with and com pletely cover the cushion sealing layer or gasket as shown in Figure 8.
In Figure 1, I have illustrated a cap, e. g., a crown cap having a metal shell III, a cushion liner ll united therein by a heat fusible or heat coagulable adhesive, and a facing material 12 in the form of a-center spot adhered to the cushion liner.
The cushion liner is preferably formed of cork composition, as shown, but may consist of natural cork, rubber, rubber composition, paper, paper board or any of the other numerous commercially available materials.
The facing material I2 is formed of chlorinated rubber preferably in the form of a very thin film. By chlorinated rubber I mean a material known in the art, and described, for example, in the patents to Gebauer, Fuelnegg and Moffett, No. 1,980,396, November 13, 1934, and Calvert, No. 1,989,632, January 29, 1935, or any other chlorinated rubber materials or rubber-like materials capable of forming an adherent film having the protective characteristics described, and capable of acting as a sealing means. By rubber-like materials, I mean synthetic rubbers which are capable upon chlorination of producing odorless and tasteless films.
I prefer chlorinated rubber which'has been suitably treated to render the same substantially transparent and devoid of taste or odor. Materials of this character are old and well known as such.
Referring to Figure 3, I have shown a strip or sheet of spotting material such as used in connection with the 'capof Figures 1 and 2. This facing material comprises the layer of chlorinated rubber l2 in the form of a thin film having on its underside a substantially coextensive layer or thin stratum of adhesive backing l3 whereby a facing is adhered to the cushion liner. While I have indicated the use of a layer of adhesive I3, I find .that the chlorinated rubber is rendered tacky and adhesive under heat and may thus be adhered to a. cork composition disc or other cushion liner material without the use of an applied adhesive as shown in Figure 9. It is preferred, however, to provide a thin layer l3 of adhesive, since this will also act as a reinforcing material or backing for the chlorinated rubber film and thereby strengthen the strip facing material for use in automatic cap spotting material.
Referring to Figures 4 and 5, the facing layer I2 is united by a thin layer of adhesive I3 or preferably by its own inherent adhesiveness when rendered tacky under heat as shown in Figure 10, to a thin backing and strengthening layer ll of paper or of metal foil such as tin foil or aluminum foil which in turn is provided with an adhesive layer l5 whereby spots formed from the facing material will be adhered to the cushion liner. The strips or sheets so formed have the cept that the mounting or backing layer I6 is,
of thin paper. As with the built-up facing material structure described in connection with Figures 4 and 5, the layer of adhesive" may be omitted and the facing film l2 rendered tacky as by-heating, and in this'condition as shown in Figure 10, adheredto the mounting or reinforcing layer IS. The strip or sheet is likewise of desired thinness and fulfills the necessary requirements for use in high speed spotting machines;
Since the facing layer I2 is transparent, it is often desirable to impart to the spot or overall facing, a definite shade or color. For this purpose, it may be (1) suitably coated with a paint or other coating H as shown in Figure 11 on the underside, or (2) the adhesive 13 may have I incorporated in it the desiredpigment as shown in Figure 12, or (3) the chlorinated rubber itself' may be suitably pigmented or colored'as shown in Figure 13.
For example, I have discovered that it is possible to apply a film or a very thin coating it of aluminum paint to the under-surface of the film l2 and thereafter apply over this colored surface 'a suitable adhesive l3 as shown in Figure 11 whereby the composite built-up facing may be either directly adhered to the cushion liner II or adhered to a suitable mounting or backing of foil II or paper I6. The aluminum film visible through the rubber film I! gives the appearance of an aluminum spot or facing.
Instead of applying a color film of paint to the under-surface of the chlorinated rubber facing layer, I include a pigment, such as aluminum in the adhesive layer Hi. In this connection, I have discovered that by mixing finely powdered aluminum with a thermo-plastic adhesive of the type described in the patent to Warth, No. 1,956,481, April 24, 1934,. and this coating applied to a chlorinated rubber film that the facing layer gives a very beautiful appearance and resembles aluminum foil. .In making the pigmented adhesive composition, sufficient thermoplastic is used and added -to the aluminum powder to produce a mass suited to spreading and capable of providing the desired adherence to the cushion liner or foil or paper backing. For example, the thermo-plastic will constitute substantially 60% and the aluminum powder 40% and the product is prepared by simply mixing the two constituents. Also, this pigmentized adhesive layer may be used with the facing material [2.
The adhesive'should contain solvents compatible with the rubber film so as not to affect the latter adversely.
As a further modification, the chlorinated rubber may itself -be pigmented as shown in Figure 13 and/or be provided with an under surface coating of a suitable colored paint, lacquer or -other film-as shown at H! .in Figure 11.
Also, instead of an adhesive such as that described in the said Warth patent, I prepare an cushion liner without-the use of a separate adhesive, and in this connection, strips or sheets of the cushion liner material, e. g., cork composition, may be formed with an adherent film of chlorinated rubber applied as an adherent plastic and tacky spreadable mass, or in solution in a solvent, such as chloroform or carbon tetrachloride, which solvent may be easily'evaporated to leave a smooth continuous rubber film as shown in Figure 9. Likewise, similar sheets or strips may be provided with a chlorinated rubber film adhesively bonded theretc'by one of the adhesives mentioned herein or other suitable adhesive means as shown in Figure 8. A construction .wherein the composition cork liner or similar liner material is provided with an integral thin coating or film of the resistant or protective chlorinated rubber may be suitably punched to form sealing discs as, shown in Figures 8 and 9 having an overall 'or spot facing of the chlorinated rubber. Of course, such overall facings may be prepared by applying coextensive coatings or filmsof chlorinated rubber to preformed discs of cushion adherent mass which becomes non-tacky on' material as hereinabove described.
With respect to the chlorinated rubber; this maybe prepared as a solution or as a spreadable cooling. The solution or tacky mass may be applied directly to cushion liner material in sheet,
strip or disc form or to a suitable backing of metal foil, paper or adhesive tissue, such as gutta percha tissue. In the case of the direct application to the cushion liner material as stated, the composite structure is punched to form suitable overall liner and facing discs. Where the chicrinated rubber is applied to the backing, the sheets are preferably out into strips of suitable size for feeding on a cap spotting machine.
It is preferred to form the chlorinated rubber in independent sheetsorstrips and to combine the same with cushion liner-material, or the backing material of foil or paper, or an ad- I hesive tissue.. The chlorinated-rubber sheet or adhesive consisting of a mixture of chlorinated rubber and the pigment, e. g., aluminum powder, and coat the same as a thin film upon the under-surface of the transparent layer or film,
of chlorinated rubber facing material as shown in Figures 11 and 12. I t m As heretofore stated, the chlorinated rubber facing layer may be directly adhered to the strip can be combined directly with the cushion' liner material, foil or paper by rendering the rubber tacky through mild heating, and the rubber, will resume its non-tacky condition on cooling.
.Also, the rubber film will be combined with an adhesive which may be spread on the rubber film or combined therewith in a tissueor sheeted form. This composite or laminated material in strip form is suitable for capspotting machines, and as regards a tissue, gutta'percha tissue or gutta percha tissue compositionis satisfactory and for a spreadable adhesive, the nitrocelluloseresin thermoplastic of the said Warth patent is quite satisfactory.
Where a backing of paper or foil is used as shown in Figures 5 and 7-, or direct union with cushion linermaterial is carried out as shown in Figure 3, I also, in some cases, use an adhesive to unite the chlorinated preformed rubber film to the backing or liner material, and, .in this connection, one of the chlorinated rubber-adhesive laminated materials just above described can be so combined with sheets or strips of the paper or'foil, or with the cushion liner material. That is to say, I use a gutta percha tissue or. a nitrocellulose-resin thermoplastic as the adhesive for uniting the preformed chlorinated film to the backing or base layer,
Similar adhesive will be usedto unite the foil or paper backing layer to the cushion liner material.
It is to be observed that in the forming of the laminated facing material the preformed film, the reinforcing backing layer, which in some cases includes only a layer of adhesive, and in others a backing of paper or foil, can be combined in strip form to produce a suitable builtup structure.
Where it is desired to unite the preformed chlorinated film to cushion liner material or to a backing of paper, foil oradhesive, the latter may be heated and the chlorinated film applied thereto, so that the respective layers are united. This union will be accomplished by reason of a mild'fusing imparted to the chlorinated rubber through contact with such heated backing or base layer, or by reason of the tacky condition of the adhesive layer to which the chlorinated film is applied, e. g., where gutta percha tissue or the thermoplastic material described in the Warth patent are used.
In some cases also, the adhesive will be applied to the metal foil or to the paper backing, or to the cushion liner material, and the preformed rubber film will then be combined therewith.
In all cases where the preformed film and preformed layers of cushion liner material or backing material, such as metal foil, paper or adhesive are combined, it is preferred to use a suitable pressure to unite the layers, and, asstated, the chlorinated rubber film may be subjected to a mild heating or the base materials to which it is applied may have an elevated temperature, or the adhesive upon such base materials is in a tacky condition, or the adhesive upon the chlorinated rubber is in tacky adherent state.
I produce facing material in accordance with this invention in which the thickness of the layer of chlorinated rubber is between substantially .0015" to .0017}.
are present upon the containers to which the caps are applied.
In referring to a resin-nitrocellulose adhesive as set forth in said Warth patent, the composition which I employ, i. e., a plastic varnish coating, is prepared as a flowable mass, such as a paint or lacquer, and is spread or sprayed upon the sur- 7 face of a sheet or strip of paper or foil, as desired, forming a thin film of .0012 to .0016" in thickness. This composition comprises a. resin, preferably a synthetic resin of the polyhedric alcohol-polybasic acid (Glyptal) type, or a rezyl resin, or a vinylite resin (vinyl acetate), a cellulose derivative, such as nitro-cellulose, a plasticizer, such as aliphatic tartrates and phosphates, and a solvent, preferably an organic solvent, having proper drying properties. These vinylite resins are usually polymers of vinyl acetate or vinyl chloride, or mixtures of vinyl acetate and the chloride. Vinyl acetate particularly can be combined well with soluble cottons (nitro-cellulose).
The resin is not limited to the glyptal or rezyl I type, but should be one capable of dissolving the I am able to use a foil backing having a thickness of .0005 to .00065.
With respect to the paper layer, I do not prefer to use an absorptive paper, but rather a paper treated to reduce absorption, for example, a latex impregnated paper or a latex wax impregnated paper. Instead of impregnating the paper with the latex or latex Wax. the paper may be coated with a very thin film 19 of this material as shown in Figure 14. I find that gutta percha or an adhesive as described in said Warth patent or the chlorinated rubberitself will adhere firmly to such a latex or latex wax treated paper, and that very thin fihns of the adhesive need only be employed to secure the chlorinated rubber film to the paper backing. The thickness of the paper layer is usually less than .002".
Gutta percha is not preferred as the adhesive, since it is relatively thick, whereas films of resinnitrocellulose adhesive in accordance with said Warth patent may be prepared of a thickness of less than .002, whether used to unite the chicrinated film to a backing and to unite the backing to the cushion liner material, or when used to unite the chlorinated rubber film directly to the cushion liner material without the interposition of an additional reinforcing layer. This ability to obtain a very thin facing is highly important, in that it permits the facing of chlorinated rubber in the case of spot caps to lie substantially fiush with the cushion liner material and prevent movement of the spot with relation to the cushion liner or its separation therefrom,
particularly where relatively narrow sealing lips cellulose derivative and having a high coefilcient of plasticity.
The resin or the composition may-be modified by adding thereto, in small percentage, non-drying vegetable oils, such as castor oil, to increase the plasticity. Semi-drying or drying oils are not desirable as they undergo oxidation.
Any suitable cellulose derivative may be used and in addition to nitro-cellulose, I use cellulose acetate. The resin serves to modify and enhance the adhesive properties of the nitro-cellulose, and hence is a desirable modifying agent.
I have mentioned the particular plasticizers, but it will be understood that others equally capable of acting as a solvent for the nitro-cellulose are employed. In this connection, I prefer butyl tartrate. Also tricresylphosphate and phthalates, such as dibutyl and amyl phthalates are employed. I also use methyl abietate with either ethyl or butyl alcohol. This latter is particularly useful for dissolving dammar and. nature resins, as well as vinylite resins. where rubber is desired as a constituent of the plastic varnish. I find that a plastic coating of rubber containing varnish is also useful as the adhesive.
The organic solvent preferably consists of toluol, butyl acetate, which promotes quick drying, and denatured alcohol, but, of course, other solvents capable of dissolving the mixture may be employed. Ethyl acetate and butyl alcohol may also be used in the solvent mixture, as well as benzol, although the latter is not preferred. I do not wish to be limited with respect to the solvent employed, provided, it imparts to the adhesive material proper drying properties.
A preferred composition of the above ingredients is given below:
Synthetic resin 15.4 Nitrocellulose 8.3 Plasticizer 6.3 Toluol 31. Butyl acetate 24. Denatured alcohol 15.0
The solution is applied to the paper or foil by spreading or spraying and will quickly dry as a thin continuous film at temperatures above The resultant film, is below .002" in thickness and is usually about .0012" in thickness to .0016" on the dry basis.
Other adhesives which may be used are a dispatible with the rubber and which will adhere to the cushion liner material or to a backing where this is employed. However, Warth patent is most desirable because the thickness of the adhesive film can be regulated and a built-up facing material layer produced which will have a thinness such that when the cap is applied to a container, there will be no disruption or bulging such as would loosen the facing from the cushion liner-or displaceitto destroy the seal. A further type of adhesive consists of the chlorinated rubber itself, coated either in tacky plastic condition upon the facing of chlorinated rubber or applied thereto as a thin filmin solution as above described. Another adhesive which I' have used with'considerable success for adhering the chlorinated rubber film directly to the cushion backing or to a backing material, such as paper or foil, is a mixture of wax and latex which may be used in either liquid form or as a preformed tissue. Such an adhesive, whether a. tissue or liquid, is thermoplastic and substantially translucent and colorless. The wax and latex may be mixed in any suitable manner, for example, as set forth in the patent to .Weiss, No. 1,563,410, December 1, 1925.
With respect to the adhesives employed for adhering the foil or paper to the cushion liner where a backing 'is employed in the built-up fstructure,,these may be in accordance with the Warth patent above mentioned or any of the other adhesives herein described. Gutta percha also may be used, but it is preferredto use those adhesives herein mentioned which are compatible with paper or foil as well as with composition the adhesive of the cork and other cushion liner materials, and
which can be used in such thinness as to be economical and particularly to reduce the overall thickness of the facing.
1. Acap suitable for sealing pressure foods and beverages comprising a metal shell, a-cushion liner therein, a backing layer united to said cushion liner and a facing of chlorinated rubber on the outer surface of said backing and constituting the exposed surface of the cap.
2. A cap suitable for sealing pressure foods and beverages comprising a metal shell, a cushion liner therein, a paper backing layer united to said cushion liner and a facing of chlorinated rubber on the outer surface of said backing and constituting the exposed surface of the cap.
3. A cap suitable for sealing pressure foods and beverages comprising a metal shell, a cushion liner therein, a paper backing layer treated to reduce its absorptive properties and united to said cushion liner and a facing of chlorinatedrubber on the outer surface of said backing and constituting the exposed surface of the cap.
4. A cap suitable for sealing pressurefoods and beverages comprising a metal shell, a cushion liner therein, a backing layer of adhesive united to said cushion liner and a facing of chlorinated rubber on the outer surface of said backing and constituting the exposed surface of the cap.
5. A cap suitable for sealing pressure foods and beverages comprising a metal shell, ,a cushion liner therein, a backing layer of metal foil united to said cushion liner and a facing of chlorinated rubber on the outer surface of said backing and constituting the exposed surface of the cap.
CHARLES E. MCMANUS.