US3171560A

US3171560A - Crown closure

Info

Publication number: US3171560A
Application number: US347918A
Authority: US
Inventors: Robert P Desch; James R Rittenhouse
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1964-02-27
Filing date: 1964-02-27
Publication date: 1965-03-02
Anticipated expiration: 1982-03-02
Also published as: GB1059154A

Description

March 2, 1965 P. DESCH ETAL 3,171,560

CROWN CLOSURE Filed Feb. 27, 1964 INVENTOR ROBERT E DESCH JAMES R. RITTENHOUSE ATTORNEY United States Patent 3,171,560 CRGWN CLOSURE Robert P. Desch, East Hemptield Township, Lancaster County, and James R. Ritteuhouse, Lancaster Township,

Lancaster County, Pa., assignors to Armstrong Cork Company, Lancaster, Pa, a corporation of Pennsylvania Filed Feb. 27, 1964, Ser. No. 34-7313 7 Claims. (Cl. 215-39) This invention relates to a crown closure and more specifically to a crown closure having a two-part plastic liner in which the portion exposed to the bottle contents is relatively hard so as to be abrasion-resistant and the portion in engagement with the lip of the container for sealing purposes is soft and yieldable to conform to irregularities in the glass finish thereby ensuring a proper seal on a container. This is a continuation-in-part application of our copending application Serial No. 162,785, filed December 28, 1961, now abandoned.

Considerable work has been done in the development of a crown closure having a plastic liner capable of adequately sealing carbonated beverages and beer. This development Work has brought about two types of plastic lined crown closures: (l) a crown in which a preformed liner is adhesively secured to a crown previously coated with a sanitary lacquer; and (2) a crown in which a liquid material is disposed therein in the shape desired and fused in position to form the liner of the desired contour in engagement with the sanitary lacquer coating on the crown.

In both of these systems, the compound from which the liner is formed is of a formulation which will produce a liner of suflicient yieldability to conform to any irregular configuration on the lip of the container so that it will adequately seal on the lip. In lining compositions of this type the central portion of the liner is usually so soft that it is easily cut or scratched by the serrated edges of the fluted skirt when a plurality of crown closures are tumbled in a hopper in the conventional capping equipment. To prevent the cuts and scratches from penetrating the liner and marring the metal therebeneath, it is necessary to provide a liner which is much thicker than would be required ordinarily to merely protect the metal of the crown from the contents of the container and vice versa. Another disadvantage of plastic liners of this thick soft type is that there is more plasticizer for the resins present to deleteriously affect the contents of the container. If, on the other hand, the plastic liner be made of a formulation having low plasticizer content producing a liner which is sufiiciently hard to resist the abrasion of the crowns in the hopper, it is found that this hard material does not conform readily to the surface of the glass container and a proper seal is not obtained.

In those instances where the harder, tougher material is used, the central area of the liner can be relatively thin in comparison to the sealing area and still resist the cutting and scratching produced by these other crowns. This results in a two-fold diminution of the plasticizer content because not only is there less plasticizer in the compound but there is also less compound present in this central area.

By this invention there is produced a crown having a desirable sealing liner formed of two separate compo sitions; one is sufiiciently tough and hard to protect the center of the crown from abrasion and penetration during the time the crowns are being hoppered; and the other formulation is sufliciently soft and yieldable to conform to irregular conformations in the lip of the container. This sealing compound is placed in the crown as a sealing ring or annulus positioned so as to be directly over the sealing lip of the container when the crown is affixed thereon.

In order that my invention may be more readily under- 33E569 Patented Mar. 2, 1965 stood, it will be described in connection with the attached drawing, in which FIGURE 1 is a plan view of the interior of a crown closure with the liner in place;

FIGURE 2 is a cross-sectional view taken along line 11-11 of FIG. 1 of a crown in inverted position showing the contour of the liner; and

FIGURE 3 is a crown-sectional view showing the crown of this invention in sealing position on a container.

Referring to the drawing, there is shown a crown 2 having a center top panel 3 and a depending fluted skirt 4. The crown itself is of the conventional type used in packaging carbonated beverages in which the fluted skirt is crimped over a lip 5 on the glass finish of the container 6 to hold the crown liner in sealing engagement with the neck finish 7 of the container.

The metal from which the crown shell is formed is previously treated with a sanitary lacquer to prevent corrosion. The sealing liner composed of two parts is shown generally at 8 and comprises a relatively thin center portion 9 covering the portion of the center panel of the crown exposed to the contents of the container 6 when the crown is affixed in sealing position on a con tainer. Surrounding this relatively thin center portion 9 of lining material is a sealing ring 10 which is generally semicircular in cross section as shown in FIGURE 2. This sealing ring 10 is formed of a more resilient and yieldable composition than the thin portion of the liner covering the central panel 3.

The following are specific examples of suitable formulations for applying a spray coating to the center panel after which a sealing ring is applied over the spray coat- Example 1 The center coating: Grams lllarvinol VR51 (Naugatuck Chemical Co.)-

polyvinyl chloride homopolymer 1500 Diisodecyl phthalate 300 Di2-ethyl heXyl phthalate 7S Polyethylene glycol 400 mono-oleate (Glycol Chem. Co.) 30 Ferro 760X (Ferro Chemical Corp.) Zn-Caepoxy stabilizer 30 Mineral spirits (aliphatic solvent) 225 Solvesso 150 (Esso Standard Oil Co.) aromatic petroleum solvent 225 Sealing ring or annulus:

Marvinol VR-SO (Naugatuck Chemical Co.)-

polyvinyl chloride homopolymer 1000 Di-Z-ethyl hexyl phthalate 800 Stayrite (Witco Chemical Company) Ca-Zn stearate stabilizer 30 Example 2 The center coating: Grams PVC-74 vinyl chloride-vinyl acetate copolymer (92.2% vinyl chloride-7.8% vinyl acetate) i500 Di-2-ethy1 hexyl phthalate 300 Polyethylene glycol 400 mono-oleate (Glycol Chem. Co.) 30 Feiro 760K (Ferro Chemical Corp.) Zn-Caepoxy stabilizer 30 Mineral spirits (aliphatic solvent) 225 Solvesso (Esso Standard Oil Co.) aromatic petnoleum solvent 225 Sealing ring or annulus:

PVC-74 vinyl chloride-vinyl acetate copolymer 92.2% vinyl chloride-7.8% vinyl acetate) 1000 Di-Z-ethyl hexyl phthalate 8G0 Stayrite 90 (Witco Chemical Company) Ca-Zn stearate stabilizer 30 The following is a specific example of a formulation suitable for roller coating onto the sheet metal in place of spray coating the center area of a formed crown.

Example 3 V The center coating: Grams Marvinol VR-51 (Naugatuck Chemical Co.)

polyvinyl chloride ho mopolymer 1500 Epoxidized soybean oil may be substituted for the polyepoxide monomer utilized as the secondary plasticizer in the above formulation.

The specific vinyl chloride polymers are selected because of their inert characteristics making them suitable as a major constituent for closure liners coming in contact with food products. In carrying out the invention suitable plasticizers for the vinyl resins may be used such as: di-n-hexyl azelate, 2-ethyl hexyl diphenyl phosphate, di- 2-ethyl hexyl adipate, acetyl tributyl citrate, di-n-butyl sebacate, butyl phthalyl butyl glycoate, diisodecyl phthalate and di-2-ethyl hexyl phthalate.

Polyethylene glycol mono-oleate is used as a viscosity depressant. All of the above plasticizers and other ingredients have been approved by the Food and Drug Administration for use in materials coming in contact with food for human consumption. The mineral spirits and aromatic petroleum solvents are removed from the liner and are never present when the crown is in sealing position on the container. The formulation for the sealing ring contains no solvent but merely the vinyl resin plus the plasticizer and stabilizer. The same resins and plasticizers can be used for the sealing ring as in the center spot. It will be noted, of course, that more plasticizer is present in the formulation from which the sealing ring is formed. This high plasticizer content gives greater resiliency to this portion of the liner.

It is necessary for the various components of the liner material to' have certain physical properties both from the standpoint of desirability as a lining material and from the standpoint of application to the crown shell. Since one of the most practical methods of applying the center coating is by use of spray equipment, it is necessary to produce this material in dispersion form of proper viscosity for spray application. 'It has been found that a dispersion of the material of Examples 1 and 2 for the center coating containing from 61% by weight to 81% by weight of non-volatiles is satisfactory for spray application. The preferred percentage of non-volatiles is 77. This dispersion having 81% non-volatile has a viscosity of 480 centipoises at 2 rpm. and 272 centipoises at 20 rpm. on the Brookfield R.V.F. scale. On the Castor Severs Extrusion Rheometer with a 0.1553 centimeter diameter orifice; 60 seconds to readings were:

At 20 lbs./ sq. inch pressure-761 centipoises at 60 sec. At 50 lbs./sq. inch pressure-917 centipoises at 60 sec. At 80 lbs./ sq. inch pressure-.-967 centipoises at 60 sec.

The physical properties of the material for the center coating and the material for the sealing annulus were determined from 2%. mil films of each drawn on tinplate. For the center coating formulation a tensile strength ranging from 7,187 to 1,218 lbs./ sq. inch and an elongation ranging from 81% to 417% was found to be satisfactory. The hardness test on the Sward rocker hardness tester ranges from 3.7 to 49.3 seconds on the index on which plate glass is 2 minutes and 18 seconds. On the standard General Electric impact test there is no failure at 60% elongation. On the Taber abrasion tester the materials require from 45 to 533 revolutions to abrade 1 mil. On the Tukon hardness test outlined in ASTM-D1475-57T at 10 gram load the Knoop hardness number ranges from 8.4 to 1. Its wet wear abrasion in deionized water requires from .9 hour to 4 hours to abrade 1 mil and in 5% sodium carbonate it requires from 1.4 hours to 4.2 hours to abrade 1 mil. When submerged in 50% by weight ethyl alcohol at 115 F. for 24 hours, the weight loss due to extraction by the alcohol is from 0% to 18%. On similar tests for the sealing ring the following results were obtained: Tensile strength, ranges from 3,012 to 675 lbs./ sq. inch; elongation from 224 to 610%; Sward rocker hardness, 1.6 to 15; impact, no failure at 60% elongation; Taber abrasion requires 4 to 600 revolutions to abrade 1 mil; Tukon hardness, too soft to measure; wet wear abrasion, deionized water from 1.2 hours :to 6 hours per mil, 5% sodium carbonate 1.0 to 7.3 hours per mil.

For the roller coat composition of Example 3 it has been found in actual practice that the viscosity should have a range of to seconds on a #2 Zahn cup.

For ease of application it has been found desirable to utilize a material for the center spot having a viscosity as recited above for spraying by conventional spray nozzles as the crowns are passing along on a carrier. The sealing ring or annulus is preferably put in position in the crown by means of a nozzle which deposits a ribbon of the material in the crown in the form of an annulus. This is preferably done by a stationary nozzle positioned above a rotating chuck. The nozzle is off center from the chuck a distance sufiicient to place the ribbon of material in the crown in an area directly above the sealing area 7 of the bottle on which the crown will be subsequently placed. The crown is rotated on a chuck beneath the nozzle with care being exercised to ensure that the crown makes only one complete revolution beneath the dispensing nozzle to form a complete annulus with no overlap.

Before application of the center coating and sealing annulus the crown shell is heated to approximately 275 F. After the center spot and the annulus have been placed in position, the crowns are passed through an infrared heating tunnel where the vinyl resin is fused. Due to the fact that the center coating is applied to the hot crown the residual heat of the crown drives off most of the solvent before the annulus is positioned therein. Any solvent remaining is removed during the final fusmg step.

The resulting crown has a center coating of vinyl composition which is relatively hard and tough passing the physical properties outlined above. When engaged by the rough cut fluting of other crowns while in shipment or in hoppers this center coating is not deleteriously affected. The sealing annulus is, of course, more resilient and may be more readily deformed by any imperfection in the glass finish to ensure proper sealing of a container when the cap is placed in position thereon and crimped about the bead of the container.

When the center coating is applied by the roller coat technique, the process is carried out by applying a thin film of the center coating material over the entire flat sheet of metal from which the crowns are to be manufactured. After this coating operation the metal sheets with the coating applied are passed through a suitable oven in which the resin is fused. The sheets are then passed through a suitable punch press which punches the crown closures from the sheet. These punched crowns with the coating applied over the entire interior surface are then subjected to the nozzle for the application of the sealing ring as explained earlier. After the sealing ring has been positioned in the crown, the crowns are passed through a suitable heating chamber to fuse the sealing ring.

FIGURE 3 of the drawing shows the relative position of the sealing ring or annulus 10 directly over the lip 5 of the container 6. The relatively thin center portion 9 is shown directly above the opening in the container. It will be seen from this arrangement that the center area can come in direct contact with the contents of the container but very little of the container contents will engage the sealing ring or annulus.

For best results it has been found that the sealing ring or annulus should have a resin to plasticizer ratio falling within the range from two parts of vinyl resin to one part of plasticizer by weight to one part vinyl resin and one part plasticizer by weight to give a final product after fusing of the proper yieldability for sealing. The coating in the center of the crown must, of necessity, be tougher and it has been found that a resin to plasticizer ratio falling within the range from 6.7 parts of vinyl resin to one part of plasticizer to two parts of vinyl resin to one part plasticizer gives a center coating of the desired toughness.

While in the specific example given above, mention is made of spraying the center coating, it will be understood, of course, that other suitable means of application may be utilized, such as daubers, dispensing valves, roll coaters, etc. So far as the annulus is concerned, this could be preformed and placed in the crown as a precured annulus.

It is believed that the method stated herein is most suitable for this type of crown, however, the specific elements entering into the crown are not so limited.

Certain of the compounds formulated have very desirable corrosion resistant characteristics for use in connection with steel or tinplated steel. In those cases where aluminum sheets are used for making the crowns, corrosion resistance is not a problem. All of the compounds mentioned herein are satisfactory from the standpoint of taste in that they do not impart a deleterious taste to the contents in the container.

It will be obvious from the foregoing that this invention produces a crown in which a plastic liner is adhered to the sanitary lacquer finish of the crown and the liner is abrasion resistant in the center portion but has sufficient resilience in the sealing area to be readily deformed to adequately seal on the container.

We claim:

1. A crown closure having a panel portion, a peripheral fluted skirt portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising a homopolymer of polyvinyl chloride containing plasticizer in the ratio of one part plasticizer to one and one-quarter parts resin, a coating covering the surface of the panel within the sealing annulus, said coating comprising a homopolymer of polyvinyl chloride and plasticizer in which the ratio is one part plasticizer to four parts resin.

2. A crown closure having a panel portion, a peripheral fluted skirt portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising the following formulation:

Grams Polyvinyl chloride homopolymer 1000 Di-2-ethyl hexyl phthalate 800 Ca-Zn stearate stabilizer 30 a coating covering the surface of the panel within the sealing annulus, said coating comprising the following formulation:

Grams Polyvinyl chloride homopolymer 1500 Diisodecyl phthalate 300 Di-Z-ethyl hexyl phthalate 75 Polyethylene glycol 400 mono-oleate 30 Zn-Ca-epoxy stabilizer 30 Mineral spirits 225 Aromatic petroleum solvent 225 3. A crown closure having a panel portion, a peripheral fluted skirt portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising a polymer of polyvinyl chloride containing plasticizer in which the plasticizer to resin ratio ranges from one part plasticizer to two parts of resin to one part plasticizer to one part resin, a coating covering the surface of the panel within the sealing annulus, said coating comprising a polymer of polyvinyl chloride and plasticizer in which the plasticizer to resin ratio ranges from one part plasticizer to 6.7 parts of resin to one part plasticizer to two parts of resin.

4. A crown closure having a panel portion, a peripheral fluted skirt portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising a homopolymer of polyvinyl chloride containing plasticizer in which the plasticizer to resin ratio ranges from one part platsicizer to two parts fo resin to one part plasticizer to one part resin, a coating covering the surface of the panel within the sealing annulus, said coating comprising a homopolymer of polyvinyl chloride and plasticizer in which the plasticizer to resin ratio ranges from one part plasticizer to 6.7 parts resin to one part plasticizer to two parts resin.

5. A crown closure having a panel portion, a peripheral fluted skirt portion, and an annular sealing gas-- ket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising a polymer of vinyl chloride-vinyl acetate containing plasticizer in which the plasticizer to resin ratio ranges from one part plasticizer to 1.25 parts of resin to one part plasticizer to one part resin, a coating covering the surface of the panel within the sealing annulus, said coating comprising a polymer of vinyl chloride-vinyl acetate and plasticizer in which the plasticizer to resin ratio ranges from one part plasticizer to 5 parts of resin to one part plasticizer to two parts resin.

6. A crown closure having a panel portion, a peripheral fluted portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising the following formulation:

Grams Vinyl chloride-vinyl acetate copolymer 1000 Di-Z-ethyl hexyl phthalate 800 Zn-Ca stearate stabilizer 30 a coating covering the surface of the panel within the sealing annulus, said coating comprising the following formu- 7. A crown closure having a panel portion, a pcrepheral fluted skirt portion, and an annular sealing gasket on the interior surface of said panel portion, said gasket being in the form of an annulus deposited on the surface of the panel portion a spaced distance from the fluted skirt, said gasket comprising the following formulation:

Grams Vinyl chloride polymer 1000 Di-Z-ethyl hexyl phthalate 800 Zn-Ca stearate stabilizer 30 r 3,171,560 7 I 8 a coating covering the surface of the panel within the Polyepoxide monomer sealing annulus, said coating comprising the following Polyethylene glycol 400 mono-oleate formulation: Zn-Ca-epoxy stabilizer 7 I I Grams Mineral spirits i l l i polymer 1500 5 Aromatic Petroleum Solvent Di-2-ethyll1exyl phthalate 375 No references cited.

Claims

1. A CROWN CLOSURE HAVING A PANEL PORTION, A PERIPHERAL FLUTED SKIRT PORTION, AND AN ANNULAR SEALING GASKET ON THE INTERIOR SURFACE OF SAID PANEL PORTION, SAID GASKET BEING IN THE FORM OF AN ANNULUS DEPOSITED ON THE SURFACE OF THE PANEL PORTION A SPACED DISTANCE FROM THE FLUTED SKIRT, SAID GASKET COMPRISING A HOMOPOLYMER OF POLYVINYL CHLORIDE CONTAINING PLASTICIZER IN THE RATIO OF ONE PART PLASTICIZER TO ONE AND ONE-QUARTER PARTS RESIN, A COATING COVERING THE SURFACE OF THE PANEL WITHIN THE SEALING ANNULUS, SAID COATING COMPRISING A HOMOPOLYMER OF POLYVINYL CHLORIDE AND PLASTICIZER I N WHICH THE RATIO IS ONE PART PLASTICIZER TO FOUR PARTS RESIN.