AU647498B2

AU647498B2 - Liquid composition and process for treating aluminium or tin cans to impart corrosion resistance and reduced friction coefficient

Info

Publication number: AU647498B2
Application number: AU80693/91A
Authority: AU
Inventors: Tomoyuki Aoki; Shinichiro Asai; Yasuo Iino; Shigeo Tanaka; Masayuki Yoshida
Original assignee: Henkel Corp
Current assignee: Henkel Corp
Priority date: 1990-06-19
Filing date: 1991-06-13
Publication date: 1994-03-24
Anticipated expiration: 2011-06-13
Also published as: CA2085489A1; DE69106510D1; ES2067942T3; EP0533823A1; EP0533823B1; WO1991019828A1; AU8069391A; BR9106572A; ATE116694T1; CA2085489C; DE69106510T2

Abstract

A corrosion resistant film with a low coefficient of friction that facilitates automatic conveying can be formed on the surface of tin-plated steel or of aluminum, particularly DI cans of one of these types of metal, by contacting the aluminum or the tin plated steel with an aqueous liquid composition having a pH in the range from 2.0 to 6.5 and containing: (A) from 1 to 30 g/L of phosphate ions, (B) from 0.1 to 10 g/L of condensed phosphate ions, and (C) from 0.1 to 20 g/L as solids of a water-soluble resin component selected from the group of resins, including mixtures of resins, having general chemical formula (I) wherein n is an integer within the range from 10 to 80 inclusive; each of X and Y is independently selected from hydrogen or a group "Z" with formula (II), except that at least 15 % the total of all of the X and Y groups in this component of the composition are Z rather than hydrogen; and (II) wherein each of R1 and R2 in each of the phenyl rings in the formula independently is selected from the group consisting of alkyl groups containing from 1 to 10 carbon atoms per group and hydroxyalkyl groups containing from 1 to 10 carbon atoms per group.

Description

OPI DATE 07/01/92 AOJP DATE 13/02/92 APPLN. ID 80693 91 )N TREATY (PCT) PCT NUMBER PCT/US91/04250

INTER

(51) International Patent Classification 5 C23C 22/23 (11) International Piblication Number: WO 91/19828 Al (43) International Publication Date: 26 December 1991 (26.12.91) (21) International Application Number: (22) International Filing Date: Priority data: 2/160443 19 June 1 2/179271 6 July 19 PCT/US91/04250 13 June 1991 (13.06.91) 990 (19.06.90) 90 (06.07.90) (71) Applicant (for all designated States except US): HENKEL CORPORATION [US/US]; 300 Brookside Avenue, Ambler, PA 19002 (US).

(72) Inventors; and Inventors/Applicants (for US onlyI TANAKA. Shigeo [JP' JP]; 2-26-37, Kohnan, Kohnan-ku, Yokohama-shi, Kanagawa-ken AOKI, Tomoyuki [JP/JP]; 3-2-50, Higashi Kaigan Minami, Chigasaki-shi, Kanagawa-ken YOSHIDA, Masayuki [JP/JP]; No. 5 Nihon Parker Sbataku, 20-4, Nakao-cho, Asahi-ku, Yokohama-shi, Kanagawa-ken IINO, Yasuo [JP/JP]; 203, No. 2 Zuhden, 1-8-20, Nakahara, Hiratsuka-shi. Kanagawaken ASAI, Shinichiro [JP/JP]; Nihon Parkerizing Hiratsuka Shataku, 2566, Shinomiya, Hiratsuka-shi, Kanagawa-ken (JP).

(74)Agent: WISDOM, Norvell, Jr.; Henkel Corporation, 140 Germantown Pike, Suite 150, Plymouth Meeting, PA 19462 (US).

(81) Designated States: AT (European patent), AU, BE (European patent), BR, CA, CH (European patent), DE (European patent), DK (European patent), ES (European patent), FR (European patent). GB (European patent), GR (European patent), IT (European patent), LU (European patent), NL (European patent), SE (European patent), US.

Published With international search report.

4749 (54) Title: LIQUID COMPOSITION AND PROCESS FOR TREATING ALUMINIUM OR TIN CANS TO IMPART COR- ROSION RESISTANCE AND REDUCED FRICTION COEFFICIENT H R t I Z -C -N H R 2

(II)

(CH--CH)n_ (57) Abstract A corrosion resistant film with a low coefficient of friction that facilitates automatic conveying can be formed on the surface of tin-plated steel or of aluminum, particularly DI cans of one of these types of metal, by contacting the aluminum or the tin plated steel with an aqueous liquid composition having a pH in the range from 2.0 to 6.5 and containing: from I to 30 g/L of phosphate ions, from 0.1 to 10 g/L of condensed phosphate ions, and from 0.1 to 20 g/L as solids of a water-soluble resin component selected from the group of resins, including mixtures of resins, having general chemical formula wherein n is an integer within the range from 10 to 80 inclusive; each of X and Y is independently selected from hydrogen or a group with formula except that at least 15 the total of all of the X and Y groups in this component of the composition are Z rather than hydrogen; and (II) wherein each of Ri and R 2 in each of the phenyl rings in the formula independently is selected from the group consisting of alkyl groups containing from I to 10 carbon at6ms per group and hydroxyalkyl groups containing from 1 to 10 carbon atoms per group.

WO 91/19828 PCT/US91/04250 LIQUID COMPOSITION AND PROCESS FOR TREATING ALUMINIUM OR TIN CANS TO IMPART CORROSION RESISTANCE AND REDUCED FRICTION COEFFICIENT TECHNICAL FIELD The present invention relates to a novel liquid composition for treating the surface of tin-plated steel and/or aluminum and alloys that are predominantly aluminum (both the pure metal and alloys being denoted hereinafter by the word "aluminum" unless the context requires otherwise), particularly the surfaces of drawn-and-ironed (hereinafter cans made from these materials. The composition imparts an excellent corrosion .resistance and paint adhesiveness to the surface of such a can after its formation by the drawing and ironing of metal sheet but before its painting or printing. This novel liquid composition also imparts the excellent.mobility or slideability, low frictional resistance, which is required for the smooth conveyor transport of such a can. The composition also is relatively low in pollution potential, because it contains no deliberately introduced chromate or fluorine. The invention also relates to processes for using the composition according to the invention.

BACKGROUND ART In the field of liquid compositions for treating the surface of tin-plated DI can of the aforementioned type, one example is the invention disclosed in Japanese Patent Application Laid Open [Kokai or Unexamined] Number 01- 100,281 [100,281/89]. This particular invention comprises a film-forming liquid composition for the treatment of metal surfaces in which the liquid composition has a pH of 2 to 6 and contains 1 to 50 g/L of phosphate ions, 0.2 to 20.0 g/L of oxyacid ions, 0.01 to 5.0 g/L of tin ions, and 0.01 to 5.0 g/L of condensed phosphate ion. Treatment with this conversion treatment liquid composition lays down a strongly corrosion-resistant phosphate film on the surface of a tin-plated DI can.

The inventions disclosed in Japanese Patent Application Laid Open Number 01-172,406 [172,406/89] and U. S.

WO 91/19828 PCT/US91/04250 2 Patent 4,457,790 are examples of a treatment method intended to develop corrosion resistance and adhesiveness through the use of water soluble resin. These inventions teach methods for treating metal surfaces with a solution which contains a derivative of a suitable polyhydric phenol compound and an aminomethylene substituted phenolic polymer or oligomer respectively.

The treatment baths previously employed to treat the surface of aluminum and aluminum alloy of the aforementioned type can be generally classified into chromate types and non-chromate types. The chromate types typically take the form of chromic acid chromate conversion treatments and phosphoric acid chromate conversion treatments. Chromic acid chromate conversion treatments entered into practical application in about 1950, and these are still widely used for heat exchanger fin material and the like. This type of conversion treatment bath is based on chromic acid (Cr0 3 and hydrofluoric acid (HF) and also contains an accelerator. It lays down a film which contains modest quantities of hexavalent chromium.

The phosphoric acid chromate conversion treatment derives from the invention in United States Patent Number 2,438,877 (1945), and this type of conversion treatment bath is based on chromic acid (CrO 3 phosphoric acid

(H

3

PO

4 and hydrofluoric acid It forms a film whose principal component is hydrated chromium phosphate (CrPO 4 4H 2 As this film does not contain hexavalent chromium, it is currently widely employed as a paint undercoating treatment for the body and lid of beverage cans.

The invention disclosed in Japanese Patent Application Laid Open [Kokai or Unexamined] Number 52-131937 [131,937/ 77] is a typical prior art example within the realm of nonchromate types of treatments for aluminum. The disclosed treatment bath comprises an acidic aqueous coating solution (pH approximately 1.0 to 4.0) which contains zirconium or titanium or a mixture thereof, as well as phosphate and fluoride. The application of this conversion treatment WO 91/19828 PCT/US91/04250 3 bath exemplary of the prior art to the surface of aluminum generates a conversion film whose principal component is zirconium oxide or titanium oxide. While the absence of hexavalent chromium is an advantage associated with nonchromate type treatment baths, the corrosion resistance and paint adherence achieved with such baths in the prior art are inferior to those with chromate type treatments. Furthermore, both the chromate type treatments and non-chromate type treatments contain fluorine, while environmental considerations have recently created demand for a fluorinefree surface treatment bath, Within the sphere of treatment methods which use water-soluble resin in order to impart corrosion resistance and paint adherence to aluminum, the following are listed as exemplary of the prior art: Japanese Patent Application Laid Open Number 61-91369 [91,369/861 and Japanese Patent Application Laid Open Number 01-172406 [172,406/89].

In these methods, the metal surface is treated with a solution which contains a useable derivative of a polyhydric phenolic compound. However, it is difficult with these methods to form an adequately stable film on the surface of aluminum, and this precludes the appearance of a satisfactory performance (corrosion resistance).

During the metal can manufacturing process, the high friction coefficient of the exterior can surface causes the can surface to have a poor slideability during conveyor transport of the can, which causes the can to tumble over sideways and thus impairs the transport operation. Can transportability is a particular issue with respect to transport to the printer in a high speed continuous manufacturing plant. It is therefore important in the can manufacturing industry to reduce the static friction coefficient of the exterior can surface without compromising the adhesiveness of any paint or lacquer to be coated on the can. The invention disclosed in Japanese Patent Application Laid Open Number 64-85292 [85,292/89] is an example of a method for improving the slideability. This inven- PCT/US91/04250 Henkel Corporation et al. Av/iHPJim 10 Juni 592 4 tion concerns an agent for treating the surfaces of metal cans.' This particular agent contains water-soluble organic material selected from phosphate esters, alcohols, monovalent and polyvalent fatty acids, fatty acid derivatives, and mixtures of the preceding.

EP-A-0 091 166 discloses a process and compositions for conversion coatings on treated or untreated metal surfaces, e.g. untreated aluminum.

The solutions disclosed in EP-A-0 312 176 do not contain any resin but contain phosphate and condensed phosphate and tin ions being used for conversion coating of metal surfaces.

DESCRIPTION OF THE INVENTION Problems to Be Solved by the Invention The above-described invention does lead to the formation of a strongly corrosion-resistant phosphate film on conventional tin-plated DI can; however, the tin-plated DI can produced over the last few years has used smaller quantities of tin plating in response to economic pressures. This has necessitated surface treatments with a far better corrosion resistance than before, and this demand is not entirely satisfied by invention The other above described inventions do not always result in a satisfactorily stable corrosion resistance with the tin-plated DI can produced over the last few years or with aluminum cans.

Finally, the above-described invention does in fact improve the slideability, but it sometimes does not improve the corrosion resistance or paint adhesiveness to an adequate degree.

Thus, with respect to cans carrying small quantities of tin plating or aluminum cans, the prior art leaves problems unsolved with regard to the formation of a highly corrosion resistant film and with regard to improvements in the slideability and paint adhesiveness.

SUBSTITUTE

SHEEI

4a Summary of the Invention As a concrete means for solving the aforementioned problems which arise in the prior art, -the present invention provides a liquid composition for treating the surface of tin-plated DI can, said liquid composition being characterized by a pH of 2.0 to 6.5 and containing 1 to 30 g/L of phosphate ions, 0.1 to 5 g/L of condensed phosphate ion if used on tin plated steel or 0.1 to 10 g/L of condensed phosphate ions if used on aluminum, and 0.1 to 20 g/L (as solids) of water-soluble resin with the following general ,;i

-,C

SUBSTITUTE SHEET WO 91/1928 PCF/US9/04250 formula:

OH

XY

-(CH-CH2) n where n is an integer within the range from 10 to 80 inclusive; each of X and Y is independently selected from hydrogen or a group with the formula given below, except that at least 15 of the total of all the X and Y groups in this component of the composition are Z rather than hydrogen; and H R 1 Z C -N H

R

2 where each of R 1 and R 2 independently is a C 1 to C 10 alkyl and/or hydroxyalkyl group.

Application of a surface-treatment liquid composition according to the present invention provides an aluminum or a tin-plated DI can surface with an excellent corrosion resistance and paint adhesiveness prior to its painting or printing and also generates the excellent slideability necessary for smooth conveyor transport of the can. Finally, because the treatment bath according to the present invention does not contain chromium or fluorine, the waste water treatment load is substantially reduced compared to most prior treatment baths, especially for aluminum.

Details of Preferred Embodiments of the Invention The surface-treatment liquid composition according to WO 91/19828 P~Tr/S91/04250 6 the present invention is 'an acidic treatment liquid composition whose essential components are phosphate ions, condensed phosphate ions, and water-soluble resin of a particular type.

The phosphate ions can be introduced into the treatment liquid composition using phosphoric acid (H 3 P0 4 sodium phosphate (Na 3

PO

4 and the like. Its content should fall within the range preferably of 1 to 30 g/L and more .preferably of 5 to 15 g/L. At below 1 g/L, the reactivity is relatively poor and film formation generally will not be satisfactory. A good-quality film can be formed at values in excess of 30 g/L, but the cost of the treatment liquid composition is increased and the economics are therefore impaired.

The condensed phosphate ions are selected from pyrophosphate ions, tripolyphosphate ions, and tetrapolyphosphate ions. The acid or salt can be used to introduce the condensed phosphate ions. For example, when pyrophosphate ions are to be introduced, pyrophosphoric acid (H 4

P

2 0 7 sodium pyrophosphate (Na 4

P

2 07), and the like can be used.

This component should be present at 0.1 to 5 g/L for treating tin plated steel or at 0.1 to 10 g/L for treating aluminum, and the range of 0.4 to 1 g/L for tin plate or to 4.0 g/L for aluminum is particularly preferred. At values less than 0.1 g/L, a satisfactory film will not be formed because of weak etching activity. However, the etching activity is undesirably high at values in excess of g/L on tin plate or 10 g/L on aluminum, and the filmforming reaction is inhibited.

The water-soluble resin used by the present invention comprises polymers with the general formula already given above. The molecular weight is too low at values of n in this formula below 10, so that little or no improvement in corrosion resistance will normally be observed. At values for n of 81 and above, the aqueous solution has a reduced stability, which will normally generate problems in practical applications. Functional groups R 1 or R 2 containing 11 or more carbons usually would reduce the stability of an aqueous solution containing them. The group Z is preferably -CH 2 N(CH3) 2 or -CH2N(CH 3

)CH

2 CH2OH. When less than of the total of all the X's and Y's in the resin are Z, there are usually stability problems with the compositions that would otherwise be according to the invention.

The water soluble resin should be present at a concentration of from 0.1 to 20 g/L on a solids basis. At values less than 0.1 g/L, stable film formation on the can surface highly problematic. Values in excess of 20 g/L are uneconomical due to the increased cost of the treatment solution.

The pH of the treatment liquid composition must be' from 2.0 to 6.5. Etching is heavy and film formation is impaired at pH values less than 2.0. At values in excess of 6.5, the liquid composition life is shortened bedause the resin tends to precipitate and sediment. The pH can be adjusted through the use of an acid, for example, phosphoric acid, nitric acid, hydrochloric acid, hydrofluori ezCid (if wc-te. wate! enta :ti-n w-i-t uridc is-net apro-eble)-, and the like, or through the use of a base, for example, sodium hydroxide, sodium carbonate, ammonium hydroxide, and the like.

When metal ions tin, aluminum, or iron) are introduced into the treatment liquid composition, precipitation may occur due to the formation of a resin/metal ion complex, and a chelating agent in addition to the resin as specified above should preferably be added to the treatment liquid composition in such cases. While this chelating agent is not specifically restricted, chelating agents useful within this context are exemplified by tartaric acid, ethanolamine, gluconic acid, oxalic acid, and the like.

The method for preparing the surface-treatment liquid composition according to the present invention can be briefly described as follows. Prescribed quantities of phosphate ions and condensed phosphate ions as described above are dissolved in water with thorough stirring. ,When fe ~lV WO 91/19828 PCT/U591/04250 8 the pH of this liquid composition is not already less than 7, it is adjusted to below 7 using the appropriate acid as noted above. The water-soluble resin specified by the present invention is then added and completely dissolved while stirring, and the pH is adjusted if necessary as discussed above.

The film which is formed by means of the present invention's surface-treatment liquid composition is believed to be an organic and inorganic composite film which is composed primarily of the resin and phosphate salts (the main component is believed to be tin phosphate when tin plated substrates are treated). While the invention is not limited by any theory, it is believed that the substrate is etched by the phosphate ions and condensed phosphate ions, the pH at this time is locally increased at the interface, and phosphate salt is deposited on the surface. Moreover, the amino group in the resin has a chelating activity, and it may form a type of coordination compound with the fresh surface of the substrate generated by etching. The simultaneous presence of the condensed phosphate ions is thought to promote formation of resin/metal coordination compounds, and this may make possible the stable formation of the composite film on the surface over a broad pH range.

A process according to the invention for treating tinplated DI can using a surface-treatment liquid composition of the present invention will now be considered. The present invention's treatment liquid composition can be applied by the following process sequence, which is a preferred sequence for a process according to this invention.

i. Surface cleaning: degreasing (a weakly alkaline cleaner is typically used on tin-plated DI can, while an alkaline, acidic, or solvent based degreaser may be effectively used on aluminum cans.) 2. Tap water wash 3. Film-formation treatment (application of the treatment liquid composition according to the present invention) WO 91/19828 PCI'/US91 /04250 9 treatment temperature: ambient to 80 0 C treatment method: spray treatment time: 2 to 60 seconds 4. Tap water wash Wash with de-ionized water 6. Drying A surface-treatment liquid composition according to the present invention can conveniently be used at treatment tempenatures from room temperature up to 80 0 C; however, it is generally preferably used at 40 to 60 0 C. The spray time preferably should be 2 to 60 seconds. At less than 2 seconds, a highly corrosion-resistant film will not usually be formed. No improvement in performance is observed for treatment times in excess of 60 3econds, but the cost is increased. Accordingly, the preferable treatment time will fall in the range from 2 to 60 seconds.

The practice of the invention and the superior performance of surface-treatment liquid composition according to the present invention may be further appreciated from the following working and comparison examples.

Examples General Methods and Criteria for the Examples The corrosion resistance of treated tin plated cans was evaluated using the iron exposure value which was measured in accordance with the teaching of United States Patent No. 4,332,646. The corrosion resistance is better at lower IEV values, and a score below 150 is generally regarded as excellent. The corrosion resistance of aluminum DI cans was evaluated based on the resistance to blackening by boiling water. A treated aluminum DI can was immersed for 30 minutes in boiling tap water, and the degree of discoloration (blackening) was visually evaluated in order to determine the resistance to blackening by boiling water. The following scale was used to score the resistance to blackening by boiling water: no blackening WO 91/19828 PCT/US91/04250 blackening of part of the surface blackening of the entire surface x.

The paint adhesiveness was evaluated based on the peel strength as follows: The surface of the treated can was coated with an epoxy/urea can paint to a film thickness of to 7 micrometers; this was baked at 215 o C for 4 minutes; the can was then cut into a 5 x 150 mm strip; a test specimen was prepared by hot-press adhesion with polyamide film; and this was peeled by the 180 peel test method.

Accordingly, the paint adhesiveness improves as the peel strength increases, and values in excess of 1.5 kilograms of force per 5 millimeters of width (hereinafter mm-width") on tin plate or in excess of 4.0 kgf/5 mm-width on aluminum are generally regarded as excellent.

The slideability was evaluated by measuring the static friction coefficient of the exterior surface of the can.

Thus, the slideability improves as the static friction coefficient declines, and values below 1.0 are generally regarded as excellent.

Tin-plated DI cans were prepared by drawing and ironing tin-plated steel sheet. They were cleaned with a 1% hot aqueous solution of a weakly alkaline degreaser (FINE CLEANER 4361A, registered brand name of Nihon Parkerizing Company, Limited), then sprayed with a surface-treatment liquid composition according to the invention as describi below for each specific example.

Aluminum DI cans were prepared by drawing and ironing aluminum alloy (A3004) sheet. They were cleaned with a 3 hot aqueous solution of an acidic degreaser (PARCLEANT 400, commercially available from Nihon Parkerizing Company, Ltd.), then sprayed a with surface-treatment liquid composition according to the invention as described below for each specific example.

Example 1 A tin-plated DI can was cleaned as described above, then sprayed with surface-treatment liquid composition 1 as described below, heated to 60 0 C, for 30 secondt, then WO 91/19828 PCT/US91/04250 11 washed with tap water, sprayed with de-ionized water (with a specific resistance'of at least 3,00' '00 ohm-cm) for seconds, and, finally, dried in a hot air-drying oven at 180 0 C for 3 minutes.

Surface-treatment liquid composition 1 phosphoric acid (H 3 P0 4 10.0 g/L 3-

(P

4 3 7.2 g/L) sodium pyrophosphate (Na4P20 7.10H 2 1.0 g/L 4- (P27 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 1, in which n in the general formula given above for this resin averaged 40, half of the total of the X's and Y's in the formula were Z, and Z was

-CH

2 N(CH3)CH2CH2H pH 4.0 (adjusted with sodium hydroxide) Water-soluble resin 1 was synthesized as follows.

CELLOSOLVEM solvent in an amount of 100 grams (hereinafter was introduced into a 1,000 milliliter reaction flask equipped with a condenser, nitrogen inlet tube, overhead stirrer, and thermometer, and 60 g of poly{4-vinylphenol} with a molecular weight of 5,000 was added and dissolved. Then 40 g of 2-methylaminoethanol and 100 g of deionized water were added, and this was reacted by heating to 50 o C. Then 40 g of 37 aqueous formaldehyde solution was added over 1 hour, followed by stirring at 50 0 C for 2 hours and by.stirring for an additional 3 hours at 80 0 C. The reaction product was cooled, 15 g of 85% orthophosphoric acid was added, and 700 g of deionized water was also added. The resin was then precipitated by the addition of 10 aqueous sodium hydroxide solution until the pH of the reaction solution reached 8 to 9. The precipitated resin was filtered off, washed with water, and dried.

Example 2 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 2, heated to WO 91/19828 PCT/US91/04250 12 o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 2 phosphoric acid (H 3 P0 4 10.0 g/L 3-

(PO

4 7.2 g/L) sodium pyrophosphate (Na P207 10H20): 1.0 g/L 4-

(P

2 0 7 0.4 g/L) resin solids: 0.4 g/L of water soluble resin 1 as in Example 1 pH 5.0 (adjusted with sodium carbonate) Example 3 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 3 heated to 60 o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 3 phosphoric acid (H 3 P0 4 20.0 g/L 3-

(PO

4 14.4 g/L) sodium pyrophosphate (Na4 P20 10H20): 1.0 g/L

(P

2 0 7 0.4 g/L) resin solids: 8.0 g/L of water-soluble resin 1 as in Example 1 pH 4.0 (adjusted with sodium hydroxide) 2 Example 4 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 4 heated to o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 4 phosphoric acid (H 3 P0 4 15.0 g/L 3-

(PO

4 10.9 g/L) sodium pyrophosphate (Na P 2 0 7 10H20): 2.5 g/L 4-

(P

2 0 7 1.0 g/L) resin solids: 4.0 g/L of water-soluble resin 1 as in WO 91/19828 PCT/US91/04250 13 Example 1 pH 3.0 (adjusted with sodium carbonate) Example Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 5 heated to 60 o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 75% phosphoric acid (H 3

PO

4 30.0 g/L 3-

(PO

4 21.6 g/L) sodium tripolyphosphate (Na 5

P

3 0 10 0.6 g/L 5-

(P

3 0 10 5- 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 1 as in Example 1 pH 3.5 (adjusted with sodium hydroxide) Example 6 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 6 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 6 phosphoric acid (H 3 P0 4 10.0 g/L 3- (P0 4 7.2 g/L) sodium pyrophosphate (Na P207*10H20): 1.0 g/L 4-

(P

2 0 7 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 2 pH 4.0 (adjusted with sodium hydroxide) Water soluble resin 2 was made in the same way as water soluble resin 1, except that the quantities of material used were 60 g of poly-4-vinylphenol, 20 g of 2-methylaminoethanol, and 40 g 37% formaldehyde solution. As a result of these changes, n in the general formula given for the resin had an average value of about 40 as before, but only about 25 of the total of all X's and Y's in the WO 91/19828 PCT/US91/04250 14 formula were of type Z.

Example 7 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 7 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 7 phosphoric acid (H 3 P0 4 10.0 g/L 3- (P0 4 3: 7.2 g/L) sodium pyrophosphate (Na4 207 10H20): 1.0 g/L 4-

(P

2 0 7 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 3 pH (adjusted with sodium hydroxide) Water soluble resin 3 was made in the same way as water soluble resin 1, except that 24 g of dimethylamine were substituted for the 40 g of 2-methylaminoethanol used in making water soluble resin 1. As a result of this change the Z groups in water soluble resin 3 had the formula -CH 2

N(CH

3 2 but the average value of n in the general formula remained about 40 and about 50 of the total X's and Y's in the general formula were of type Z.

Comparison Example 1 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 8 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 8 75% phosphoric acid (H 3 P0 4 10.0 g/L 3- (P0 4 7.2 g/L) resin solids: 2.0 g/L of the same water-soluble resin as in Example 1.

pH 4.0 (adjusted with sodium carbonate) WO 91/19828 PCT/US91/04250 Comparison Example 2 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 9 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 9 phospho:-ic acid (H 3

PO

4 1.0 g/L 3-

(PO

4 0.72 g/L) resin solids: 2.0 g/L of the same water-soluble resin as in Example 1 pH 7.0 (adjusted with sodium hydroxide) Comparison Example 3 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 10 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 75% phosphoric acid (H 3

PO

4 10.0 g/L 3- (PO, 7.2 g/L) sodium pyrophosphate (Na P207 10H20): 1.0 g/L 4- (P207 0.4 g/L) resin solids: 0.05 g/L of the same water-soluble resin as in Example 1 pH 4.0 (adjusted with sodium carbonate) Comparison Example 4 Tin-plated DI can was cleaned using the same conditions as in Example 1 and was then treated with a 30 second spray of surface-treatment liquid composition 11 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 11 phosphoric acid (H 3

PO

4 1.0 g/L (P 3- 72 g/

(PO

4 0.72 g/L) WO 91/19828 PCT/US91/04250 16 sodium pyrophosphate (Na P207 10H20): 1.0 g/L 4-

(P

2 0 7 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 4 pH 4.0 (adjusted with sodium hydroxide) Water-soluble resin 4 had the chemical formula:

OH

SCX

CH

2

SO

3

H

-(CH -CH 2) n- The average value of n was about Water-soluble resin 4 was synthesized as follows: g of poly{4-vinylphenol} (molecular weight about 5,000) was placed in a 1,000 mL reaction flask equipped with a condenser, nitrogen inlet tube, overhead stirrer, and thermometer, and 500 g of 1,4-dioxane was added for dissolution. An amount of 80 g of liquid sulfur trioxide (SO 3 was added over a time of 1 hour while the mixture was maintained at around 100 C. This was followed by heating to 800 C and reaction for 4 hours while stirring. Neutralization was carried out with 10 sodium hydroxide solution and the solvent was distilled off.

The results of the experiments and comparison experiments on tin plated DI cans are reported in Table 1, and they confirm that the conditions according to the present invention afford an excellent corrosion resistance, adhesiveness, and slideability, with all these factors being superior to those obtained in the comparison examples.

WO 91/19828 PCT/US91/04250 17 Table 1. Test Results Peel Strength, Frictional IEV kqf/5 mm-width Coefficient Example 1 40 2.0 0.8 Example 2 40 2.0 0.8 Example 3 50 2.0 0.8 Example 4 40 2.0 0.8 Example 5 40 2.0 0.8 Example 6 60 2.0 0.8 Example 7 40 2.0 0.8 Comparison Example 1 250 1.5 Comparison Example 2 950 1.3 Comparison Example 3 500 1.5 Comparison Example 4 750 1.3 Example 8 An aluminum DI can was cleaned as described above, then sprayed with surface-treatment liquid composition 12 as described below, heated to 60 0 C, for 30 seconds, then washed with tap water, sprayed with de-ionized water (with a specific resistance of at least 3,000,000 ohm-cm) for seconds, and, finally, dried in a hot air-drying oven at 180 0 C for 3 minutes.

Surface-treatment liquid composition 12 phosphoric acid (H 3 P0 4 10.0 g/L 3-

(PO

4 7.2 g/L) sodium pyrophosphate (Na4P207*10H20): 3.0 g/L 4-

(P

2 0 7 1.2 g/L) resin solids: 2.0 g/L of water-soluble resin 1, in which n in the general formula given above for this resin averaged 40, half of the total of the X's and Y's in the formula were Z, and Z was WO 91/19828 PCT/US91/04250 18

-CH

2

N(CH

3

)CH

2

CH

2

OH

pH 4.0 (adjusted with sodium hydroxide) Water-soluble resin 1 was the same as in Example 1 Example 9 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 13, heated to 0 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 13 phosphoric acid (H 3 P0 4 10.0 g/L 3-

(PO

4 7.2 g/L) sodium pyrophosphate (Na P207 10H20): 3.0 g/L 4-

(P

2 0 7 1.2 g/L) resin solids: 0.4 g/L of water soluble resin 1 as in Example 1 pH 5.0 (adjusted with sodium carbonate) Example An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 14 heated to o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 14 75% phosphoric acid (H 3 P0 4 20.0 g/L '3- (P0 4 3 14.4 g/L) sodium pyrophosphate (Na 4

P

2 0 7 .10H 2 6.0 g/L 4-

(P

2 0 7 2.4 g/L) resin solids: 8.0 g/L of water-soluble resin 1 as in Example 1 pH 6.0 (adjusted with sodium hydroxide) Example 11 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 15 heated to o C. This treatment was followed with a water wash and WO 91/19828 PCT/IS91/04250 19 drying using the same conditions as in Example 1.

Surface-treatment liquid composition phosphoric acid (H 3 P0 4 15.0 g/L 3- (P0 4 3: 10.9 g/L) sodium pyrophosphate (Na 4

P

2 0 7 10H20): 5.0 g/L 4-

(P

2 0 7 2.0 g/L) resin solids: 4.0 g/L of water-soluble resin 1 as in Example 1 pH 3.0 (adjusted with sodium carbonate) Example 12 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 16 heated to 60 o C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 16 phosphoric acid (H 3 P0 4 30.0 g/L 3- (PO4 21.6 g/L) sodium tripolyphosphate (Na 5

P

3 0 10 1.2 g/L

(P

3 0 10 0.8 g/L) resin solids: 2.0 g/L of water-soluble resin 1 as in Example 1 pH 3.5 (adjusted with sodium hydroxide) Example 13 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 17 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 17 phosphoric acid (H 3

PO

4 10.0 g/L 3-

(PO

4 7.2 g/L) sodium pyrophosphate (Na P207 10H20): 3.0 g/L 4-

(P

2 0 7 1.2 g/L) resin solids: 2.0 g/L of water-soluble resin 2 pH 4.0 (adjusted with sodium hydroxide) WO 91/19828 PCT/US91/04250 Water soluble resin 2 was made in the same way as in Example 6.

Example 14 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 18 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 18 75% phosphoric acid (H 3 P0 4 10.0 g/L 3- (P0 4 7.2 g/L) sodium pyrophosphate (Na4P207.10H20): 3.0 g/L

(P

2 0 7 1.2 g/L) resin solids: 2.0 g/L of water-soluble resin 3 pH 4.0 (adjusted with sodium hydroxide) Water soluble resin 3 was made in the same way as in Example 7.

Comparison Example An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 19 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 19 75% phosphoric acid (H 3 P0 4 10.0 g/L (P043- 7.2 g/L) resin solids: 2.0 g/L of the same water-soluble resin as in Example 1.

pH 4.0 (adjusted with sodium carbonate) Comparison Example 6 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 20 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

WO 91/19828 PCT/US91/04250 21 Surface-treatment liquid composition phosphoric acid (H 3

PO

4 1.0 g/L 3- (PO43: 0.72 g/L) resin solids: 2.0 g/L of the same water-soluble resin as in Example 1 pH 7.0 (adjusted with sodium hydroxide) Comparison Example 7 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 21 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 21 phosphoric acid (H 3 PO4): 10.0 g/L 3- (PO4 7.2 g/L) sodium pyrophosphate (Na P 207 10H0): 1.0 g/L 4-

(P

2 0 7 0.4 g/L) resin solids: 0.05 g/L of the same water-soluble resin as in Example 1 pH 4.0 (adjusted with sodium carbonate) Comparison Example 8 An aluminum DI can was cleaned using the same conditions as in Example 8 and was then treated with a 30 second spray of surface-treatment liquid composition 22 heated to 600 C. This treatment was followed with a water wash and drying using the same conditions as in Example 1.

Surface-treatment liquid composition 22 phosphoric acid (H 3

PO

4 1.0 g/L 3-

(PO

4 3 0.72 g/L) sodium pyrophosphate (Na4 207.10H20): 1.0 g/L 4- (P2074: 0.4 g/L) resin solids: 2.0 g/L of water-soluble resin 4 pH 4.0 (adjusted with sodium hydroxide) Water-soluble resin 4 was the same as for Comparison Example 4 above.

WO 91/19828 PCT/US91/04250 Comparison Example An aluminum DI can was cleaned under the same conditions as in Example 8 and was then treated with a 30 second spray of a 2 aqueous solution (heated to 500 C) of a commercial non-chromate agent (PARCOAT T K 3761, from Nihon Parkerizing Company, Ltd.). This treatment was followed by a water wash and drying under the same conditions as in Example 1.

The results of these examples and comparison examples on aluminum substrates are shown in Table 2.

Table 2. Test Results on Aluminum DI Cans Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Comparison Example 5 Comparison Example 6 Comparison Example 7 Comnparison Example 8 Comparison Example 9 Resistance to Peel Strength Blackening by in Boiling Water kgf/5 mm-width 4.0 4.0 4.0 4.0 4.0 4.0 4.0 Frictional Coefficient 0.9 x x x 2.0 1.5 2.0 1.5 4.0 1.2 1.3 1.3 1.3 1.3 Benefits of the Invention Treatment of tin-plated or aluminum DI cans using a surface-treatment liquid composition with the composition given above imparts an excellent corrosion resistance and WOo 91/19928 PCT/US91/04250 23 painting or printing. In addition, it also produces a film which has the excellent slideability necessary for smooth conveyor transport of the can.

Moreover, when the condensed phosphate ions comprises at least one selection from pyrophosphate ions, tripolyphosphate ions, and tetrapolyphosphate ions and when:

CH

3 Z

-CH

2

N

CH

3 or CHPCH

OH

Z -CH 2

-N

CH

3 a film is produced which evidences an even greater improvement in the corrosion resistance, paint adhesiveness, and slideability. The treatment solution according to this invention is substantially free from chromium and fluoride and therefore has relatively low pollution potential.

Claims

1. An aqueous liquid composition for treating the surface of tin-plated steel or of aluminum and aluminium alloys, said composition having a pH in the range from 2.0 to 4.0 and consisting essentially of water and from 1 to 30 g/l of phosphate ions, from 0.1 to 5 g/L of condensed phosphate ions if used for tin-plated steel or from 0.1 to 10 g/L if used for aluminum, and from 0.1 to 20 g/L as solids of a water-soluble resin component selected from the group of resins, including mixtures of resins, having the general chemical formula: OH -(CH CH 2 )n wherein n is an integer within the range from 10 to 80 inclusive; each of X and Y is independently selected from hydrogen or a group with the formula given below, except that at least 15% the total of all of the X and Y groups in this component of the composition are Z rather than hydrogen; and H R 1 I Z=-C-N H R2 wherein each of R 1 and R 2 in each of the Z groups in the formula independently is selected from the group consisting of alkyl groups containing from 1 to 10 carbon atoms per group and hydroxyalkyl groups containing from 1 to 10 carbon atoms per group, and the composition does not contain chromium and fluorine but optionally contains a chelating agent.

2. A liquid composition according to claim 1, wherein component is selected from the group consisting of pyrophosphate ions, tripolyphosphate ions, tetrapolyphosphate ions, and mixtures thereof.

3. A liquid composition according to claim 2, wherein, in the general chemical formula for the water soluble resin component, CH 3 Z= -0H 2 N CH 3 OH 2 CH 2 0H Z -CH 2 -N CH 3

4. A liquid composition according to claim 1, wherein, in the general chemical formula for the water soluble resin component, CH 3 Z -CH 2 -N CH 3 CH 2 CH 2 0H Z H 2 N CH 3 A liquid composition according to any one of claims 1 to 4, comprising from 5 to 15 g/L of component

6. A liquid composition according to any one of claims 1 to 5, comprising from 0.4 to 1 g/L of component when used on tin-plated steel or from 1.0 to g/L of component when used on aluminum.

7. A process for treating a drawn and ironed tin-plated steel container by contact with an aqueous liquid composition in order to form on the surface of the metal container a conversion coating layer that will increase the corrosion resistance of the container after subsequent painting or printing, characterized in that the aqueous liquid composition has a composition according to any one of claims 1 to 6.

8. A process according to claim 7, wherein the time of contact is within the range from 2 to 60 seconds, contact is by spraying, and the temperature of the liquid composition during contact is between 20 and 80 oC.

9. A process according to claim 8, wherein the temperature of the liquid composition during contact is between 40 and 6000. A process according to any one of claims 7 to 9, comprising additional steps of first degreasing and then tap water washing the container surface before contacting with the aqueous liquid composition and, in order, tap water washing, washing with deionized water, and drying after contact with the aqueous liquid.

11. A process for treating a drawn and ironed aluminum or aluminium alloy metal container by contact with an aqueous liquid composition in order to form on the surface of the metal container a conversion coating layer that will increase the corrosion resistance of the container after subsequent painting or printing, characterised in that the aqueous liquid composition has a pH in the range from 2.0 to 6.5 and consisting essentially of water and from 1 to 30 g/I of phosphate ions, from 0.1 to 10 g/L of condensed phosphate ions, and from 0.1 to 20 g/L as solids of a water-soluble resin component selected from the group of resins, including mixtures of resins, having the general chemical formula: xy y -(CH CH 2 n wherein n is an integer within the range from 10 to 80 inclusive; each of X and Y is independently selected from hydrogen or a group with the formula given below, except that at least 15% the total of all of the X and Y groups in this component of the composition are Z rather than hydrogen; and H R 1 I Z=-C-N I H R 2 wherein each of R 1 and R 2 in each of the Z groups in the formula independently is selected from the group consisting of alkyl groups containing from 1 to 10 carbon atoms per group and hydroxyalkyl groups containing from 1 to 10 carbon atoms per group, and the composition does not contain chromium and fluorine but optionally contains a chelating agent.

12. A process according to claim 11, wherein the time of contact is within the range from 2 to 60 seconds, contact is by spraying, and the temperature of the liquid composition during contact is between 20 and 800C.

13. A process according to claim 12, wherein the temperature of the liquid composition during contact is between 40 and 600C.

14. A process according to any one of claims 11 to 13 comprising additional steps of first degreasing and then tap water washing the container surface before contacting with the aqueous liquid composition and, in order, tap water washing, washing with deionized water, and drying after contact with the aqueous liquid. DATED this 7th day of December, 1993. HENKEL CORPORATION WATERMARK PATENT TRADEMARK ATTORNEYS THE ATRIUM 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA DBM:MED:BB AU8069391.WPC DOC 44 INTERNATIONAL SEARCH REPORT International Application No PrT/IUS qi/n44 n I. CLASSIFICATION OF SUBJECT MATTER (if several classification symbols apply, indicate all) 6 According to International Patent Classification (IPC) or to both National Classification and IPC C 23 C 22/23 II. FIELDS SEARCHED Minimum Documentation Searched' Classification System Classification Symbols C 23 C Documentation Searched other than Minimum Documentation .to the Extent that such Documents are Included in the Fields Searched 8 ll. DOCUMENTS CONSIDERED TO BE RELEVANT' Category i Citation of Document, 11 with indication, where appropriate, of the relevant passages 2 Relevant to Claim No.' 3 Y EP-A-0 312 176 (NIHON PARKERIZING CO., 1-8,17- LTD) 19 April 1989, see claims 1,2,4; 22 example 1; page 3, lines 18-25 (cited in the application) Y EP-A-0 091 166 (SOCIETE CONTINENTALE 1-8,17- PARKER) 12 October 1983, see claims 22 1,2,3,6,9; page 6, last paragraph page 7, paragraph 1, page 4, last paragraph page 5, line 16 A DE-A-3 146 265 (METALLGESELLSCHAFT AG) 1 16 June 1982, see claim 1; page paragraph 2 A EP-A-0 363 200 (NIPPO PAINT CO., LTD) 1 11 April 1990, see claims 1,2; example 1 II Special categories of cited documents :10 later document published after the international filing date or priority date and not in conflict with the application but document defining the general state of the art which Is not itd to undemand the principle or theory underlying the considered to be of particular relevance Invention E earlier document but pnblished on or after the international Xr document of particular relevance; the claimed invention filing date cannot be considered novel or cannot be considered to "L document which may throw doubts on priority dalm(s) or Involve an inventive step which is cited to establish the publication date of another document of particular relevance; the claimed Invention citation or other special reason (as specified) cannot be considered to Involve an Inventive step when the 'O0 document referring to an oral disclosure, use, exhibition or document Is combined with one or more other such docu- other means ments, such combination being obvic s to a person skilled "P document published prior to the international filing date but In the art. later than the priority date claimed document member of the same patent family IV. CERTIFICATION Date of the Actual Completion of the International Search Date of Mailing of this International Search Report 13-08-1991 19. 09. 91 International Searching Authority Signature of Authorized Officer EUROPEAN PATENT OFFICE M. PEIS Form PCT/ISA/210 (iecoWd heit) (Jmary 1915) Ili. L)ULUALS IS LU,4SIULKLU I UHL KLLLvXq I (LUN I I.S UtlJ I XUA L HL SL(-U.I, IJ SHLL I j Category 0Citation of Document, with indication, where appropriate, of the relevant passages Relevant to Claim No, A GB-A-2 180 854 (PYRENE CHEMICAL 1 SERVICES LTD) 8 April 1987, see claims 1,7,13 A EP-A-0 319 018 (PARKER CHEMICAL CO.) 7 June 1989 (cited in the application) A US-A-4 457 790 (ANDREAS LINOERT) 3 July 1984 (cited in the application) Form9 PCTIISAZIO lextra sbeot) tJawizy 19a5) ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. US 9104250 SA 48777 This annex lists the patent family members relating to the patent documents cited in the above-mentioned international search report. The members are as contained in the European Patent Office EDP file on 13/09/91 The European Patent Office is in no way liable for these particulars which are merely given for the purpose of information. Patent document Publication Patent family Publication cited in search report date member(s) date EP-A- 0312176 19-04-89 JP-A- 1100281 18-04-89 AU-B- 608374 28-03-91 DE-A- 3834480 27-04-89 GB-A- 2210900 21-06-89 US-Ik- 4927472 22-05-90 EP-A- 0091166 12-10-83 US-A- 4433015 21-02-84 AU-B- 564972 03-09-87 CA-A- 1197082 26-11-85 DE-A- 3311129 20-10-83 GB-A,B 2119805 23-11-83 JP-A- 58185661 29-10-83 US-A- 4517028 14-05-85 DE-A- 3146265 16-06-82 US-A- 4376000 08-03-83 AU-B- 531432 25-08-83 AU-A- 7654931 06-05-82 CA-A- 1192326 20-08-85 JP-C- 1240601 26-11-84 JP-A- 57120677 27-07-82 JP-B- 59014114 03-04-84 EP-A- 0363200 11-04-90 JP-A- 2101174 12-04-90 GB-A- 2180854 08-04-87 AU-B- 586275 06-07-89 AU-A- 6244986 26-03-87 DE-A- 3627250 26-03-87 US-A- 4747885 31-05-88 EP-A- 0319018 07-06-89 US-A- 4970264 13-11-90 AU-A- 2651888 08-06-89 JP-A- 1172406 07-07-89 US-A- 4457790 03-07-84 AU-B- 575563 04-08-88 AU-A- 2779684 15-11-84 CA-A- 1214036 18-11-86 JP-A- 59207972 26-11-84 M For more details about this annex see Official Journal of the European Patent Office, No. 12/82