JPH0216779B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to the field of container end sealing compounds and, more particularly, to a method of modifying container end sealing compounds to prevent rusting at the exposed end of a metal container end. The terminology used herein is well established in the field of container sealing. The wall of the container is known as the "body". An end closure is known as an "end." A gasket, which exists between the end and the body and is important for an air-tight or liquid-tight seal between the parts,
Also known as "lining". A plastic or liquid composition that forms a solid gasket when cooled or dried is called a “lining”.
known as. The body of the can is a cylindrical piece of sheet metal, usually made by forming rectangular pieces of metal and then joining the ends of these rectangular pieces along side seams. The metal at the end of the cylinder is flanged outward. The can is completed by placing circular pieces of metal called "ends" at each end of the cylinder and rolling the outer edges of the ends and flanges on the body into a double seam. The edges of the can are made in a separate operation by stamping a blank from a similar material, which can be tin plate, blackboard, aluminum or other metal sheet. The edge that covers the inside of the can is called the "panel." The outer periphery of the end is formed with a circular depression. This depression is called a "channel." This channel cooperates with flanges at both ends of the body. The outer edge of the channel, referred to as a "curl," is deformed upwardly and inwardly to bring the can end into contact with the inside of the flange of the can body during the first stage of the double seam forming operation. Cutting edge of metal can
"edge)" means the exposed edge of the can edge located in the curled area of the can edge. The exposed edge comes into existence when the can edge is formed by a punching operation. The cutting edge is the It is prone to corrosion due to the lack of a protective coating or lacquer on top.The remainder of the panel is generally corrosion resistant because it is covered with a protective coating that was not damaged or removed by the stamping operation.The inner walls of the channel, i.e.
The area between the channel and the panel is known as the "shoulder". A plastic or liquid composition forming the "lining" is placed in the channel at the can end. Sealing compounds for can lids ("ends") are commonly applied to the lid in liquid form. “Lining device” that applies compound to the joint area
The device is controlled by a continuously rotating chuck, a "nozzle", i.e. a needle valve, which receives and rotates the lid as an essential operating element and projects the compound downwardly onto the joint area of the lid. , essentially having a squirt gun and a quick-open/close cam that raises the needle valve and closes it at the appropriate moment. A common type of compound application equipment works in a single cycle by taking a blank closure from a stack, sliding the closure along a table, and placing it on a continuously rotating chuck where it is applied with compound. is applied and placed, pushing the closure out of the chuck, pushing it under the stack of finished closures, and placing the new closure on the chuck. After the can end is lined, it is transported to an area where the volatile components of the sealing composition are removed. Operation of the lining device causes a ring of flowable compound to form in the bond area adjacent the periphery of the can end. A ring of compound, either in liquid form or when it later dries or flows into a solid mass, is called a “lining”.
It is called. Its function is to form a gasket between the parts of the can, hermetically sealing the can. US Pat. No. 3,013,896 (Ballon et al) and US Pat. No. 3,310,196 (Flaherty) describe the basic operations used to line the can end and attach the can end to the can body. The disclosures of these patents, to the extent not given herein, are hereby incorporated by reference. A water-based can lining composition is an aqueous dispersion of a special rubber and flows into the can lining;
When dry, it gives an airtight seal. The solids portion of water-based can lining compositions ranges from about 30% to about 85% of the total composition. Part based on 100 parts of rubber (hereinafter expressed in phr)
The solid portion of a typical water-based lining composition has the following composition (all parts by weight): Ingredients Rubber 100 phr Pigments and/or fillers 50-200 phr Resin 0 -100 phr Antioxidants Less than 1% Bactericides Less than 1% Surfactants 0.5% to 10% The remaining 15 to 70% of the total composition consists of water. Conventional methods for water-based compositions include the use of oven dryers. Air drying without relying on mechanical aids,
It can also be used. An important problem when using water-based can end lining compositions is that the compositions tend to promote rust and/or corrosion in the area of the cutting edges of metal can ends. This rust or corrosion occurs primarily due to the high humidity conditions induced by the environment of the can lining operation. When a stack of can ends lined with a water-based can end lining composition is placed inside a pallet containing the stack of lined can ends, the water present in the lining composition is absorbed by the absence of air circulation. It retards the evaporation of water from the lining composition, thereby promoting corrosion in the area of the cutting edge of the can end. Components of water-based can sealing compositions may also induce rust or corrosion by various chemical means. Solvent-based can-end lining compositions are primarily solvent solutions of specific rubbers. Solvent-based can end compositions may similarly promote rusting near the cutting edges of metal can ends, but to a lesser extent than water-based can lining compositions. A number of materials have been used effectively as rust inhibitors for metal can ends. Examples of these materials are sodium hydroxide (PH11), potassium hydroxide (PH11), triethanolamine, diethanolamine, monoethanolamine, sodium benzoate, and sodium. Each of these materials is effective to some degree. The effectiveness of these materials is based on their ability to deactivate the surface of the support or components of the lining composition. Although these materials retard the formation of rust on steel can ends, it is desirable to essentially eliminate rust formation on the exposed edges of the can ends. It is an object of the present invention to provide a method and composition for preventing the formation of rust on metal can ends. It is also an object of the present invention to provide a method and composition for preventing the formation of rust on cutting edges of metal products of a type susceptible to corrosion by rust. Another object of the present invention is to provide a composition that prevents the formation of rust on the cutting edges of metal can ends while at the same time not interacting with the product contained within the can. A method has been discovered to modify container end sealing compounds so that the formation of rust on steel containers is virtually eliminated. The method consists of adding an alkali metal phosphate compound to the container sealing compound formulation prior to applying the container sealing compound to the container end. U.S. Patent No. 3941562
No. (Hollingshad) describes at least about the composition of polyacrylamide and orthophosphate source.
Discloses a method for preventing corrosion of metals in a water system by maintaining 10 ppm in the water of the system. However, this method is inadequate for preventing rust on the cutting edge of the metal can end. This is because product specifications do not always permit the inclusion of polyamide/orthophosphate compositions in products stored in cans. The terms "end lining composition" and "end lining compound" are used interchangeably in this specification. The present invention includes methods and compositions for preventing the formation of rust and/or corrosion on metal container end panels and cutting edges. The method consists of treating the container sealing compound with an alkali metal phosphate before applying the sealing compound to the edge of the container. The seal thus formed from the treated sealing compound is effective in preventing the formation of rust on the outer edge of the container edge. By adding a suitable alkali metal phosphate to the can lining compound formulation, the formulation can prevent the formation of rust and/or corrosion on the cutting edges of metal can ends. The end lining compound formulations used in this invention include both water-based formulations and solvent-based formulations. Suitable water-based formulations are discussed below. This formulation is
Contains about 15 to about 60% water and about 40 to about 85% solids by weight. The above weight percentages are based on the total weight of the formulation. The solid components are further characterized by containing the following components in the indicated amounts: Ingredient Amount (% based on total weight of solid components only) Binder 24-65 Resin 0-24 Emulsifier 0- 3 Filler 20-60 Antioxidant 0-1 The binder is rubber (SBR). Preferred resins are derived from hydrocarbons. Examples of suitable fillers are silicates such as talc, clay, and sodium silicates. In addition to the above ingredients,
Water based and edge lining compounds also contain thickeners, PH modifiers, processing aids, plasticizers, oils,
Antimicrobial protectants may be included, such as fungicides, biocides, fungicides, and coagulation aids. Suitable solvent-based formulations contain non-volatile components similar to those of ordinary water-based formulations. The particular composition of the can lining composition is not critical to the invention. Alkali metal phosphates suitable for the present invention include mono-alkali, di-alkali, and tri-alkali metal phosphates. These alkali metal phosphates can be anhydrous or hydrated. Examples of these salts are sodium phosphate, potassium phosphate, and tripotassium phosphate. It is to be understood that suitable alkali metal phosphates are not limited to the above examples. To use phosphate as a rust inhibitor,
It can be first treated with a suitable base to raise the PH of the salt to the PH level of the ring-end lining compound. If the PH of the phosphate salt is reasonably close to or compatible with the PH of the end lining composition, then the addition of base is unnecessary. Water-based can lining compositions should include from about 0.1 to about 3 weight percent phosphate, based on the weight of the lining. Although higher concentrations of phosphate can be used, no appreciable improvement in rust protection is observed when using concentrations of phosphate higher than about 3% by weight. The preferred concentration of phosphate in the lining composition is about 0.7% by weight. It may be desirable to add an alkali to the phosphated container sealing composition. The purpose of adding alkali is to prevent agglomeration during formulation of the composition. The following examples are for illustrative purposes and are not intended to limit the invention. It should be understood that other combinations of different ingredients can be used to achieve similar results. All such modifications that do not depart from the basic idea of the invention and the compositions disclosed herein are embraced within the scope of the claims. Examples 1-15 2 parts by weight of ammonia ( _NH3 ) were added to 100 parts by weight of a 33% aqueous solution of monosodium phosphate. The pH of this monosodium phosphate aqueous solution reached 7. The pH adjusted monosodium phosphate was added to the water-based bottom lining composition at a concentration of phosphate ranging from 0.5 parts to 4 parts per 100 parts of rubber. The lining composition contained the following ingredients in the values indicated (all parts by weight): Solids portion (73% of total composition) 100 parts rubber 200 parts pigments and/or fillers 1 part antioxidant 1 part bactericide 0.5-4 parts rust inhibitor 10 parts surfactant, thickener liquid part (27% of total composition) 100 parts water The specific gravity of this lining composition is , it was 1.62. Tests were conducted on various supports, such as cans and flat plates. Test conditions consisted of a minimum 72 hour exposure to 97% relative humidity. To prepare the tin plate, either in the form of a plate or in the form of a can end, the support was scored to expose the underlying steel.
This effect resulted in increased sensitivity and even more severe testing. The test results are shown in the table below. These results demonstrate that the compositions of the present invention are effective in preventing corrosion of metal container edges and metal plates in general.

【table】

TABLE As the table above shows, increasing the concentration of phosphate in the can lining compound reduces rust formation on lined cans, tin plates, and blackboards. Phosphate as low as 1 part per 100 parts of rubber will prevent rust formation on damaged can edges when exposed to 97% relative humidity for at least 72 hours. Phosphate as low as 4 parts per 100 parts of rubber will prevent rust formation on scratched slabs when exposed to 97% relative humidity for at least 72 hours. Higher concentrations of phosphate can be used. But rubber 100
No appreciable improvement in rust protection is observed when using more than 4 parts per part of phosphate.

Claims (1)

Claims: 1. Rust and corrosion prevention on metal supports, characterized in that the rubber compound consists of at least 0.1% by weight of an alkali metal phosphate based on the weight of the binder, filler and composition. Lining composition that can be used. 2. The composition according to claim 1, wherein the alkali metal phosphate is an anhydrous alkali metal phosphate or a hydrated alkali metal phosphate. 3. The composition of claim 1, wherein the alkali metal phosphate is present in an amount ranging from 0.1 to 3% by weight, based on the weight of the lining composition. 4. The composition of claim 3, wherein the alkali metal phosphate is present in an amount of at least 0.5 phr. 5. The composition of claim 3, wherein the alkali metal phosphate is present in an amount ranging from 0.5 to 4 phr. 6 100 parts by weight rubber compound binder, 50~
Rust on a metal can support, characterized in that a lining composition consisting of 200 parts by weight of filler and 0.1 to 4 parts by weight of alkali metal phosphate is prepared and this composition is applied to the metal can support. How to prevent the formation of. 7. The method according to claim 6, wherein the alkali metal phosphate is an anhydrous alkali metal phosphate. 8. The method of claim 6, wherein the alkali metal phosphate is a hydrated alkali metal phosphate. 9. Prevention of Rust Formation on Cutting Edges of Metal Can Ends by Making a Can End Lining Composition Comprising a Rubber Compound Binding Agent, a Filler, and an Alkali Metal Phosphate, and Applying the Composition to the Can End Prevention method. 10. The method of claim 9, wherein the alkali metal phosphate is selected from the group consisting of anhydrous alkali metal phosphates and hydrated alkali metal phosphates. 11. The method of claim 9, wherein a base is used to raise the PH of the phosphate to the PH level of the end lining composition. 12 Based on the weight of the composition, at least 0.1
10. The method of claim 9, wherein % by weight of phosphate is added to the end lining composition. 13 0.1-3% by weight, based on the weight of the composition
10. The method of claim 9, wherein the phosphate salt is added to the end lining composition. 14. The method of claim 13, wherein at least 0.5 phr of phosphate is added to the end lining composition. 15. The method of claim 13, wherein 0.5 to 4 phr of phosphate is added to the end lining composition. 16. A metal support characterized in that: (a) an alkali metal phosphate is added to a composition consisting of a rubber compound and a filler; (b) the lining composition thus obtained is applied to the metal support. How to prevent the formation of rust on the body. 17. The method of claim 16, wherein the alkali metal phosphate is selected from the group consisting of anhydrous alkali metal phosphates and hydrated alkali metal phosphates. 18 Using a base to raise the PH of the phosphate to the PH level of the lining composition Claim 16
The method described in section. 19. The method of claim 16, wherein at least 0.1% by weight of phosphate is used, based on the weight of the lining composition. 20 Based on the weight of the lining composition, 0.1
17. The method of claim 16, wherein ~3% by weight of phosphate is used. 21. The method of claim 20, wherein at least 0.5 phr of phosphate is added to the lining composition. 22. The method of claim 20, wherein 0.5 to 4 phr of phosphate is added to the lining composition.