DK143070B - PROCEDURE FOR CREATING A STRONG WATER-RESISTANT BOND BETWEEN ALUMINUM AND A POLYSULPHIDE MASS WITH A PRIMER - Google Patents

Description

(11) PRESENTATION 1U3070 DENMARK (S1) lnt * c '· 3 ® os J 5/02 // c 23 f 7/06 § (21) Application No. 4408/76 (22) Filed on the 50th Ββρ. 1976 (24) Race day 50. S ep. 1976 (44) The application submitted to the petition published on 25 · ΓΠ3 · Γ. 1 So]

DIRECTORATE OF

PATENT AND TRADE MARKET <30> Priority requested from it

Dec 22 1975 # 75 ^ 561 * · NO

01> THOR BØRRESEN * Strandgaten 50, 519Ο Horten * NO.

(72) Inventor: Thor Børregen * Strandgaten 50 * 5190 Horten * NO: Niels Ulrik Harder * Auderødgård * Auderød, 2980 Kokkedal, DK.

(74) Plenipotentiary in the proceedings:

The Hofman-Bang & Boutard engineering firm. (54) Process for producing a strong * water-resistant bond between aluminum and a polysulfide pulp with a primer.

The invention relates to a method for producing a strong, water-resistant bond, of the kind set forth in the preamble to the claim.

For a long time, there has been a desire or need for improved adhesion for polysulfide-based, elastic sealants for aluminum for a long time in the industry. This adhesion will usually be weakened by the effects of water and heat, and it has therefore been of great interest to improve the stated adhesion ability in the hot and humid environment.

2 1Λ 3 O 7 O

It is desirable to achieve such an enhancement of the adhesion between polysulfide-based sealants and aluminum or aluminum alloys without having to depend on the time of metal surface treatment, especially without the aluminum surface being subjected to a time-consuming treatment immediately before contacting the sealant. Such a surface treatment of the metal, e.g. structural elements, such as window frame profiles, in direct connection with the use of the metallic parts, such as structural elements, will generally be very impractical and should be avoided.

It is known to use silane-containing primers for aluminum in connection with the use of the indicated sealants, and from US Patent No. 3,457,099 it is known to add a Friedel-Crafts compound (AlCl₂, BF₂, etc.) to the silane-based primer. Furthermore, it is known to mix silane into the sealant itself ("Adhesive Age" of November 1974, pages 25-27). Phenolic resins and polyvinyl acetate have also been proposed as adhesion mediators between elastomeric sealants and various substrates ("Rubber Chemistry and Technology", February 1968, pages 149-151). There is a great deal of literature on organic sealants and their properties, and many different additives and combinations of additives have been proposed to improve the adhesion strength between the sealant and the substrate, including aluminum (see, for example, "Thioplaste", Leipzig 1971 , pages 80-85). This literature shows that the thought paths followed so far have moved towards organic binders which require the use of organic solvents with the often significant disadvantages that this entails. Neither practically nor economically, such materials and pretreatment methods are particularly advantageous, but on the contrary, they must be regarded as representing unsatisfactory solutions to the problems. Nor do they appear to give sufficiently good results in purely technical terms when it comes to polysulfide-based sealants for aluminum. Eg. For example, silanes can be hydrolyzed under the influence of water and their primer activity is lost too quickly.

3 143070

It is thus the object of the invention to provide a method for producing a strong, water-resistant bond, of the kind set forth in the preamble to the claim, whereby this bond is produced in a very effective, simple and inexpensive manner.

The process according to the invention is characterized by the characterizing part of the claim.

Thus, according to the invention, it has surprisingly been found that a strong and water-resistant bond between aluminum and polysulfide mass is obtained in a very efficient, simple and inexpensive way, namely by using as a primer on the aluminum a solution of a strongly basic reactant. , inorganic alkali metal compound.

It is admittedly from German Publication No. 1,571,198, German Publication No. 2,147,622, U.S. Pat.

3 460 955 and Burns and Bradley, "Protective Coatings for Metals", 3 'edition (1967), pages 28-31, it is known that prior to application of plastic coating, aluminum can be pre-treated with alkaline solutions.

However, the particular technical problem which comprises the combination of polysulfide pulp and aluminum and the solution to this problem stated by the invention is neither known nor obvious in view of these publications.

As the inorganic alkali metal compound or base, one or more of the highly alkaline reacting hydroxides of lithium, sodium or potassium are preferably used; in addition, sodium phosphate, potassium phosphate; also sodium silicate, potassium silicate; Preferred inorganic bases are also carbonates of alkali metals, especially lithium, sodium and potassium.

As a solvent for the inorganic base, in principle, any liquid which sufficiently dissolves the inorganic compound desired to be used in the primer can be used.

However, it is an advantage of the process of the invention that water can be used as a solvent. Lower alcohols may also be used as the solvent for the inorganic base, if desired, or mixtures of such alcohols and water are used. Moreover, the composition of the solvent is not essential, since the solvent must be evaporated from the metal surface after priming.

It has also been found that the process of the invention with the excellent result can be used in conjunction with electrolytically oxidized or chemically oxidized aluminum, including aluminum-based alloys. However, it is not necessary that the metal has been subjected to such special oxidation treatment. Incidentally, aluminum will always have an oxidic film, as the metal is oxidized by the oxygen of the air.

The concentration of base in the primer can be quite small and is most conveniently at 5 wt%, preferably about 5 wt.

1% by weight, but is not critical or decisive for the result. Essentially, after priming and subsequent drying, the metal has a thin layer of the alkali compound contained in the primer.

The primer used according to the invention has proved particularly effective in connection with a polysulfide sealant based on polymercaptan polymer.

Today, aluminum profiles, preferably in anodized form, are manufactured for use, among other things as structural elements for window frames, where as a sealing compound, predominantly poly-sulfide pulp is used. The present invention provides a very significant technical advance in this field. The primer used in the process of the invention appears to change the surface structure of the aluminum metal in a favorable manner as the metal acquires an outer molecular layer of basic nature upon application of the inorganic base. It has been found that a very good adhesion between polysulfide sealant and metal profile is obtained, since the basic molecular layer appears to act as an adhesion promoter.

The good adhesion between aluminum and polysulfide sealant is of great practical importance, not least in the case of window frames, as these are often exposed to widely varying temperature and humidity conditions. The polysulfide masses commonly used in such window frame structures to be mounted in building elements and bonded to masonry and the like are based on polymercaptan polymer (e.g. thiocol LP polymer) which can be transferred from liquid to liquid by means of an activator. solid form.

5

1A 3 O 7 O

Of inorganic bases which can advantageously be used in the process according to the invention must be stated: a) Bases with hydroxyl groups in the molecule:

LiOH, NaOH, KOH.

b) Phosphates of sodium and potassium, e.g. trisodium phosphate.

c) Sodium and potassium silicates, e.g. metasilicate.

d) Carbonates of: Lithium, sodium and potassium, e.g. After CO

In the examples below, water and ethylene glycol were used as the solvent for the inorganic base.

EXAMPLE 1

Aluminum profiles, which were electrolytically oxidized, were primed at room temperature by dipping into a solution as indicated below (wt). The last three experiments are included for comparison with tests 1-3 of the invention.

Attempts: 1 2 3 4 5 6

Water 98 99 98

Ethylene glycol 98 98

Na 2 CO 3 2

NaOH 1 2

Ca (OH) 2 2 H2SO4 2

No priming x

After 1/2 hour of drying time (in air at 28 ° C), the aluminum profiles were glued to glass with a polysulfide sealant, "PRC 408 P", designed to produce insulating panes. The samples were then allowed to cure for 1 week at room temperature, after which they were stored in water at 70 ° C for 4 weeks. After this treatment, the adhesion strength between sealant and metal was investigated.

6 143070

TEST RESULTS

1 week in water at 70 ° C K K K A K K

2 weeks in water at 70 ° C K K K A 5A K

3 weeks in water at 70 ° C K K K A 50A 10A

4 weeks in water at 70 ° C 10A K K A A A

A: Aluminum adhesion break.

K: Cohesion fractures in the sealant.

50A = 50% aluminum adhesion break.

EXAMPLE 2

An aluminum profile of anodized aluminum was primed by dipping into a 1 wt.% Aqueous solution of NaOH. The profiles were then dried in the same manner as in Example 1. After 2, 8 and 24 hours and 7, 30 and 180 days, the profiles were glued to glass with a polysulfide sealant, "PRC 408P", designed to produce insulating panes. After 1 week curing at room temperature, the samples were stored in water at 70 ° C for 4 weeks, after which the strength of adhesion was examined. In all cases, cohesion fractures were found in the grout material.

EXAMPLE 3

This example is like Example 1, Experiment 2, however, instead of NaOH, Κ0Η and LiOH were used instead. In both cases, after 4 weeks of storage in water at 70 ° C, cohesion rupture was found when examining the adhesion strength.

EXAMPLE 4

This example is like Example 1, Experiment 2, however, sodium hexametaphosphate and potassium hydrogen phosphate were used instead of NaOH. After curing and 4 weeks storage in water at 70 ° C, cohesion breaks in the sealant were found in both of these cases.

7 143070

Similar experiments were performed with silicates of sodium and potassium as inorganic base. The results of the tests may be described as good, but it turned out that these bases were not as good as the hydroxides, phosphates and carbonates listed above.

In addition, similar tests were conducted with aqueous ammonia as inorganic base, but with poor results. Volatile ammonia does not leave any coating on the metal. Experiments with ammonium salts produced poor, unsatisfactory results.

Similar tests with metals other than aluminum have been carried out, but with unsatisfactory results.

Similar experiments as in Examples 1-4 were also performed with un-anodized (untreated) aluminum as well as chemically oxidized aluminum, and these experiments yielded essentially the same good results as using anodized aluminum.

The invention also encompasses articles consisting of one or more structural elements of aluminum, including aluminum-based alloys, and polysulfide pulp, especially window frames where a highly basic reacting alkali metal compound is applied to the aluminum surface (s) in contact with the polysulfide pulp. A preferred embodiment is that the structural elements are chemically or electrolytically oxidized on the surface.

In addition, the invention comprises aluminum structural elements, including aluminum alloys, to be used in conjunction with a polysulfide mass, upon which a primer of a highly basic reacting alkali metal compound is applied to the aluminum surface (s) that come into contact with the polysulfide mass. A preferred embodiment is that the metal is in the form of electrolytically or chemically oxidized profiles and similar structural elements.

It will be appreciated from the above that the process of the invention for producing a durable, strong and aqueous bond between polysulfide pulp and aluminum is a highly effective