JPS59229484A - Rust prevention for processed can - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field 1 The present invention relates to rust prevention of processed cans.

[Prior Art 1 Metal containers, particularly metal cans for food and beverage packaging, were previously manufactured from tin-plated steel sheets. Recently, such tin cans have been largely replaced by two-piece aluminum cans, especially for beverage containers (eg, beer cans, soft drink cans). Such containers can be manufactured inexpensively due to the malleability of aluminum. This is because aluminum facilitates the production of thin-walled aluminum containers from sheet metal through drawing and ladder processing. Additionally, the use of aluminum eliminates the need for tin plating. This is because lightly drawn and ironed rust-free aluminum cans are produced by immediately treating the formed and cleaned cans with an anticorrosive conversion treatment such as ALODINE can coating.

Drawn and ironed cans (commonly known as DI cans) are made by stamping or drawing circular flat metal material into a cup-like intermediate form, which is then ironed to form a complete wall and It is manufactured by constructing a conventional can body as a single, even-thin-walled container with a bottom. For reasons such as the price of the metal itself, container manufacturers have attempted to manufacture DI cans from steel, particularly the mild steel known as black plate, solving the difficulties of forming such cans from steel. The problem remains that such steel cans quickly corrode or rust. Traditional tin plating methods to provide corrosion resistance do not work on DI cans. This is because plating after can formation is impractical;
Furthermore, it is not practical to plate the can-forming plate material. In the latter case 3-, the reason is that the tin film does not flow sufficiently during drawing and ironing to provide a continuous tin film over the entire surface of the DI can. Mild steel rusts rapidly, especially when the line is stopped during can production, and so far it has not been successful to apply chemical conversion treatment immediately after can formation and cleaning to prevent rust formation.

Such a treatment, which should be useful, should not only prevent rusting during the manufacture and during the useful life of the container, but should also allow the application of sanitary lacquers of high adhesion as internal coatings and the printing of external decorations.

[Objective of the Invention 1] We now acknowledge that the above-mentioned and other problems in the manufacture of mild steel DI cans and in the manufacture of zinc-coated ferrous metal cans and tin-coated ferrous metal cans may adversely affect the subsequent coating of the can. It has been found that treatment with an aqueous solution containing a low concentration of an amine inhibitor with a sufficiently low boiling point to volatilize on drying without leaving a residue has been found to eliminate the problem. Hereinafter, when the term DI can is used, it also includes zinc-coated iron-based metal cans and 4-tin-coated iron-based metal cans. Therefore,
An object of the present invention is to provide a method for manufacturing a rust-free iron-based metal container. More particularly, it is an object of the invention to produce DI cans from black plate and to stabilize the formed cans against rust.

It is another object of the present invention to provide a chemical treatment for removing lubricant residues and other contaminants from newly formed black play (DI) cans followed by keeping the cans free of rust. It is in. These and other objects will be more fully understood from the following description.

The present invention relates to an improvement in the method of manufacturing steel cans and coated ferrous metal cans by a drawing and ironing process in which sheet steel is drawn and thinned to produce cup-like cylindrical containers having walls of substantially uniform thickness. .

The steel sheets used to make containers by this method are generally coated with a protective oil such as cottonseed oil or dioctyl sevalenate upon receipt from the foundry. When preparing a plate for drawing and squeezing to form a container, lubricants and other forming aids are applied to the surface of the plate. For example, the surface that will be the inside of the container may be coated with an acrylic-based wax lubricant, and the opposite surface may be coated with other compositions that promote uniform metal deformation, such as molybdenum disulfide in an acrylic base. May be covered with material. Any residue of these agents remaining after squeezing and ironing must be completely removed before further processing and finishing of the container for packaging food or beverages. Typically, the squeezed and squeezed container is cleaned with an acidic or alkaline aqueous cleaning solution, then rinsed and dried. During this treatment process, the main rusting problem occurs for black play (DI) cans because the freshly cleaned mild steel surface is easily oxidized, especially in a humid atmosphere.

According to the present invention, newly formed containers can be kept rust-free during subsequent processing by applying an aqueous solution of an amine corrosion inhibitor at a low concentration of 1100 pp or less to the container surface. The use of amine-based inhibitors such as morpholine as corrosion inhibitors for steel is known in the art, for example from Japanese Patent Application No. 133472/1982.
This discloses a method for protecting mild steel sheets from corrosion by coating them with a wax or resin emulsion containing one or more parts of fatty acid salts of morpholine. However, such a process cannot be used in processing black plate DL cans. This is because the emulsion coating would have to be removed before the can can be further treated with an internal sanitary lacquer and an external decorative print or coating. Unlike the use of prior art aminic corrosion inhibitors, the morpholine or similar aminic corrosion inhibitor used in accordance with the present invention is applied as a low concentration aqueous solution in a step subsequent to cleaning or immediately after, and during subsequent drying. removed by evaporation,
Further, it provides a rust-free and clean dry can that is stable against rusting during processing. Containers treated in this manner are also suitable for applying subsequent protective coatings such as organic coatings commonly used to provide suitable food containers.

7- [Configuration and Effects of the Invention] The present invention relates to a method for protecting iron-based cans from corrosion by contacting the can surface with an aqueous solution of an amine inhibitor. In the amines useful in the present invention, 1 represents an integer from O to 1, and X represents O or N. It is a water-miscible amine having one structural unit. In particular, these water-miscible inhibitory amines have the general formula 1, R, R11R2,
R3, R4, R5 and R6 are the same or different and are hydrogen or lower alkyl having 1 to 4 carbon atoms, n is an integer of O to 1, m is an integer of 1 to 2, and X is 10-1-NH- or −
Indicates NCH, -. Unless n7!1foS m is 1, R1 and R2 may together be -CH2CH2-. It is expressed as 1. Lower alkyl groups may be straight chain or branched, including methyl, ethyl, propyl,
Included are isopropyl, n-butyl, isobutyl, 5ee-butyl and t-butyl. Preferably R7-
R6 is hydrogen or methyl.

The amine remains in solution until substantially all of the water has evaporated, and any amine remaining on the metal is sufficiently volatilized under the time and temperature conditions of the process to evaporate from the metal and further remove the amine. Preferably, none of the decomposition or synthesis products remain on the metal. Approximately 100-210
It is preferred to use rust-inhibiting amines of the above formula having a boiling point in the range of about 120-170°C.

A particularly suitable amine for the purposes of the present invention is morpholine (R,R
3, R4, R5 and R6 are hydrogen, n is 0, m is 1, X
is -0-1R1 and R2 together are -CH2CH
2), which is completely miscible with water in all proportions, has a boiling point of 128°9°C and a vapor pressure of 7,
O+nnm1-T (20°C).

Other amines that have been found useful in the practice of this invention include 3-butoxy-propylamine, dimethylamino-2-propanol, dimethylaminoethanol, diethylaminoethanol, 2-dimethylamino-
2-Methyl-1-propatol, 2-amino-2-methyl-1-propatol, monoethanolamine, ethylenediamine, dimethylaminopropylamine, propylenediamine, diethylenetriamine, N-methylmorpholine, 1,4-piperazine and N , N-dimethyl-1
, 4-piperazine.

Mono- and di-alkylamines, mono-di-cycloalkylamines, pyridine, glycols, alkanols and glycol ethers are unsuitable for the practice of this invention.

A mild steel plate (black plate) is squeezed to form a black brake DI can, which is then subjected to a cleaning operation to remove lubricant residues and other contaminants. Cleaning is generally accomplished by passing the can through a spray washer using a suitable cleaning composition. Any of the conventionally known acidic, alkaline or neutral detergents may be used, and the amine inhibitor treatment of the present invention provides equally good protection against subsequent rust formation in all cases. The cleaning process is generally performed at heated temperatures, approximately 120-212°F.
1, preferably at a temperature of about 140 DEG to 160 DEG F. Following this cleaning step, the cans are rinsed with regular tap water and then further rinsed with deionized water to ensure a salt-free surface for subsequent coating steps. The normal process following rinsing is approximately 100-250°
C5 Preferably the cans are dried in an oven at a temperature of about 150-250°C, more preferably about 200°C, and then the cans are coated on the inside with a sanitary lacquer and on the outside with a base coat or vice versa. The outer coating is then printed with the desired decorative or graphic appearance. The main rust problem occurs during the drying stage, where the hot and humid atmosphere provides near-ideal corrosion conditions on the freshly cleaned slightly mild steel surface of the Blackplay II') T can. If the can is properly cleaned at this stage, it will not have any corrosion protection and will be susceptible to corrosion effects to a high degree. While it might be hoped that the can could be dried in the absence of corrosive components and maintained in a corrosive-free atmosphere until the finish coating is applied, in reality such cleaning-only methods do not result in a rust-free environment. It turned out that it was impossible to manufacture black plate cans. It has been found that even in the absence of macroscopic corrosion, there is a first stage of rusting, referred to as microscopic rust.

However, cans treated with deionized water with a low concentration of inhibitory amine can be post-dried to a clean, rust-free surface with no microscopic signs of rust and no residual morpholine. Morpholine evaporates during drying, which is generally carried out at temperatures of about 100-250°C. Amine treatments also provide protection against rusting when drying each treatment at ambient conditions such as occur during line outages. Aqueous amine treatments are generally applied as a spray immediately following a deionized water rinse. The usual steps are wash-tap water rinse-deionized water rinse-amine solution final rinse. If desired, a separate deionized water rinse can be omitted if the salts are removed continuously from the amine final rinse. Other application methods other than spraying may also be employed, as long as the metal surfaces (internal and external) of the can are completely exposed to the amine solution. The amine aqueous solution is at room temperature (approximately 20°C)
When applied to the can surface outside, this is the most practical, but higher or lower temperatures can also be employed. As a practical matter, the spray temperature does not exceed the amine vaporization point, but steam treatment is also effective. Typically, amine solution sprays are applied at temperatures of about 15-35°C. The spray composition used in this invention consists only of an amine inhibitor and deionized water. It is important not to introduce salts at this stage. This is because salt residues remain on the can surface after evaporation of the water and amine, creating potentially corrosive conditions. Preferably, the amine is used at a concentration greater than about 50 ppm. Consistent and complete protection against rusting is obtained by moistening the can with a deionized aqueous solution containing about 11,000 p of the appropriate amine throughout the time of morpholine. 1 for high concentrations of amines and morpholine
However, as a practical matter, as a practical matter,
A minimum concentration of morpholine or other amine inhibitor may generally be employed up to about 10% by weight. Generally, the amount of amine inhibitor may be from about 20 to about 100001) IMll, preferably from about 100 to 5000 ppm. In the case of morpholine, which is the most preferred inhibitor, the amount used is generally about 50 to 10,000 p, preferably about 100 to 2
000 ppln, more preferably about 500-15 (
l Oppm. The pH of the amine solution should be about 8.0 or higher, preferably 8.5 or higher, and generally about 8.7 to 13.5. A pH of about 10.8 to 13.5 is particularly preferred.

When an amine spray solution is used in accordance with the present invention, it also helps prevent rusting that might otherwise occur in a line stoppage incident. For this purpose, the method of applying the amine inhibitor is not essential as long as the amine is present on the metal surface. As a practical matter in a process line with a final amine rinse step, the amine solution can be immediately sprayed into the cans at an early stage after each line stoppage to avoid rusting. On the other hand, about 1100 pp of amine inhibitor
or more, it can be contained during normal operation of each process to protect against rusting during shutdown. The presence of amine inhibitors in the washing and rinsing steps does not interfere with the operation or effectiveness of these steps.

To provide maximum protection during drying and post-rinsing without affecting the subsequent coverage of black plate cans,
It is important that the aqueous solution of the amine inhibitor be entirely salt-free, preferably a substantially impurity-free solution of only the amine and deionized water. The length of time that the aqueous amine solution is in contact with the metal surface does not appear to be important as long as all surfaces of the can are wetted by the solution. Generally, a few seconds of spraying for an hour (eg, about 1-5 seconds) is sufficient. Cans treated in this manner remain rust-free for an indefinite period of time even under the humid conditions normally experienced in can processing plants.

[Example 1] The present invention can be fully understood by the following examples. The examples are presented only to illustrate the invention and should not be construed as limiting the scope of the invention, as will be understood by those skilled in the art.

Example 1 A mchemRrod in Ambler, Pennsylvania
Blackplay 101 cans were cleaned by spraying at 150° C. for 21 seconds with a commercial cleaning solution using can cleaner RTDOLINE 666, available from CTS, Inc., Inc. The cans were rinsed with tap water then deionized water with a dwell time of 20 seconds between each step. The cans were then subjected to a dwell time of 40 seconds and then dried in a forced air oven at 200° C. for 3 minutes. Spot rust was observed on both the inside and outside of the ceiling and around the outside edges of all cans.

Using the same treatment conditions as above with a final rinse of 100 ppn+ morpholine in deionized water (pH 9.6), all cans were completely free of rust after oven drying. The resulting can was clean, bright, and glossy throughout the 16 inner and outer surfaces.

The test was repeated five times, and each time the morpholine-treated cans had no trace of rust and were all shiny.

Example 2 Following the process of Example 1, cans were cleaned and treated with a 1100 pp. morpholine solution in deionized water as a final rinse before oven drying. The two cans were dried at an oven temperature of 400°F for 5 and 10 minutes, respectively. All cans had a slight golden color and were free of rust.

Example 3 The entire can prepared in Examples 1 and 2 was heated to 20° C. and a relative temperature of 1
It was stored in a hot water supply room at 0.00%. There was no change in either can after 12 hours. These cans were further heated to 28°C and a relative humidity of 8
It was stored at 5% in a humidified room for 24 hours. After 24 hours, the morpholine-treated cans showed no changes, but the cans with a final rinse with deionized water only had slightly more rusting near the edges.

Further, the test was continued for one day at 35° C. and 85% relative humidity.

Only the cans rinsed with deionized water developed more rust on the edges.

The 4 day post-treated can still showed no change.

Example 4 A series of black spray (DI) cans were subjected to the following steps, and the degree of rust observed in each part of the can after each step was shown. Cleaning was done in a spray washer using a RIDOLINE 666 for 30 seconds at 150°F. In each case, observations were made for 15 minutes after completion of treatment. The meanings of the symbols are rust (-), no rust+, and slightly rust. The results are shown in the table below. The treatment process adopted is as follows.

(,) Cleaning only (1)) Cleaning and blowing c) Cleaning - one blowout 1 tap water rinse (d) washing - one blowout 1 tap water rinsing e) washing - one blowout 1 tap water rinse one blowout ionized water rinse ( f) Cleaning - 1 tap water rinse, 1 ionized water rinse, 1 ionized water rinse g) Cleaning - 1 tap water rinse, 1 ionized water rinse, 1 morpholine final rinse (100pp)
m S pH 8,9) (h) Washing - Blowout - Tap water rinse - Blowout - Ionized water rinse - Blowout - Morpholine Final rinse (100 ppm, pH8,9) - Blowout 19 - Table 20 - Example 5 According to the treatment of Example 2, A number of amines were used at a concentration of 1'000 ppm in deionized water. No rust or residue formation occurred during oven processing with either amine. Amines include morpholine, 3-butoxypropylamine, dimethylamino-2-propanol, dimethylaminoethanol, diethylaminoethanol,
2-dimethylamino-2-methyl-1-propanol,
They were 2-amino-2-methyl-1-propatur, monoethanolamine, ethylenediamine, dimethylaminopropylamine, propylene diamine and diethylene syriamine.

Patent applicant: Amkem Products, Inc. Representative: Patent attorney: Haka Aoyama 1 person Procedural amendment (Mutsu) August 14, 1980 Commissioner of the Japan Patent Office Tono Haru 1, Indication of the case 1988 Patent application No. 99676 2 Name of the invention Rust prevention of processed cans 3 Relationship with the case of the person making the amendment Patent applicant (no address indicated) Name Amkem Products Incorporated 4
Date of amendment order by Agent 5: Proprietor [Attachment] 2. Claims (1) A method for preventing rusting of DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans. Then apply the general formula % to the clean can surface [where R, R, , R2, R, , R1, R5 and R6].
are the same or different and represent hydrogen or lower alkyl having 1 to 4 carbon atoms, n is an integer of 0 to 1, m is an integer of 1 to 2, and X represents -0-1-NH- or -NCH3-. n is 0,
When m is 1, R1 and R2 together form -CH2
It may be CH2-. ] A method characterized by applying an aqueous solution of an amine represented by:

(2) The method of item 1 above, wherein the amine has a boiling point of about 100-210°C.

(3) The 1-amine has a boiling point of about 120-170°C. The method of item 2 above.

(4) The method of item 3 above, wherein the aqueous solution comprises an amine inhibitor and deionized water.

(5) The method of item 4 above, wherein the amine inhibitor is morpholine.

(6) The method of paragraph 4, wherein morpholine is contained at a concentration of about 50 to 110,000 pp and the solution has a pH of about 8.0 to 13.5.

(7) The method of paragraph 4, wherein morpholine is contained at a concentration of about 500 to 1500 ppm and the solution has a pH of about 10.8 to 13.5.

(8) cleaning the squeezed and squeezed can, contacting it with a solution of about 50 to 110,000 pp of morpholine in deionized water before drying the can, and then air drying the can at a temperature of 100°C or higher; A method for manufacturing DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans.

(9) A clean black spray comprising morpholine and deionized water) An aqueous spray solution for rust prevention for DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans.

(10) Morpholine concentration is approximately 50-10000 ppm
The composition according to Item 9 of Item 2, which is ``.

Claims (10)

[Claims] (1) Black play) A method for preventing rust on DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans, in which the surface of the can is cleaned using the general formula [where R, R, . R2, R
3, R,, R5 and R6 are the same or different, hydrogen or lower alkyl having 1 to 4 carbon atoms, n is the W number of O to 1, m is an integer of 1 to 2, X is 10-1-N )1-or-
Indicates NCH3-. When n is 0% and m is 1, R1
and R2 together may be -CH2CH2-. A method characterized in that an aqueous solution of an amine represented by 1 is applied. (2) The method of paragraph 1 above, wherein the amine has a boiling point of about 100-210'C. (3) The method of item 2 above, wherein the amine has a boiling point of about 120-170°C. (4) The method of item 3 above, wherein the aqueous solution comprises an amine inhibitor and deionized water. (5) The method of item 4 above, wherein the amine inhibitor is morpholine. (6) The method of paragraph 4, wherein morpholine is contained at a concentration of about 50 to 110,000 pp and the solution has a +lH of about 8.0 to 13.5. (7) The method of paragraph 4, wherein morpholine is contained at a concentration of about 500 to 1500 ppm and the solution has a pH of about 9.2 to 10.8. (8) cleaning the squeezed and squeezed can, contacting it with a solution of about 50 to 110,000 pp of morpholine in deionized water before drying the can, and then air drying the can at a temperature of 100° C. or higher; A method for manufacturing DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans. (9) A clean black spray comprising morpholine and deionized water) An aqueous spray solution for rust prevention for DI cans, zinc-coated iron-based metal cans, and tin-coated iron-based metal cans. (10) Morpholine concentration is approximately 50-10000 ppm
The composition according to item 9.