DK167771B1 - ADHESION PRINCIPLES BASED ON POLYVINYL ACETALS AND THEIR USE - Google Patents

Description

i o DK 167771 B1

The invention relates to adhesion primer coatings which provide the metal surfaces thus treated with excellent corrosion resistance which does not penetrate the coating paint and which can be manufactured and used without the simultaneous use of chromate pigments. The invention also relates to the use of these adhesive primers on the basis of metal surfaces, especially of iron, zinc and aluminum.

Adhesion primer coatings must first and foremost provide metal parts, especially those used in shipbuilding or in the manufacture of other steel structures, temporary corrosion protection and later be repainted. As wash primers in layer thicknesses from 8 to 12 µm or shop primers in layer thicknesses from 8 to 40 µm, they must withstand thermal loads as they arise from welding so that they remain pore-free and no later develop say some corrosion sites at the weld seam. Oxidically drying alkyd resins are commonly used as cover lacquers.

Furthermore, it is desirable to provide metal objects whose cover or intermediate lacquers are thermally crosslinked with an adhesion primer which acts in a similar manner, although this does not apply to temporary corrosion protection, since the individual coatings are carried out continuously in succession.

However, in addition to the improvement in the adhesion of the lacquer structure, these foundations also provide excellent corrosion protection. However, it is stated that the known adhesion-primers-Varnishes, which are usually intended to contain a good mode of action, contain phenolic resins, break through the coating and cause discoloration. For structural parts to be temporarily protected, 30 to date are used as cover lacquered long-oiled, gasoline-soluble alkyd resins as binders, as these reduce the tendency for leaching. Other tire varnishes, e.g. Like other conventional lacquer systems, on the basis of cortical alkyd resins which are soluble in aromatic hydrocarbons and / or alcohols, or nitrocellulose varnishes, a mixture of polymers based on a) vinyl chloride and b) vinyl isobutyl ether or vinyl acetate are not suitable for this purpose. Grunding 2 UK Ί6 /// Ί bl of metal parts, the lacquer of which is later to be thermally crosslinked, has hitherto been impossible or associated with the reduction of corrosion protection, as by combinations of alkyd and urea resins, due to the penetration of the adhesion foundation.

The reason for the breakdown is undoubtedly to search the phenol resin component. Thus, if a phenolic resin adhesive primer is omitted, no penetration occurs. But in that case, the adhesion bases provide no or only 10 insufficient corrosion protection, and the adhesion properties deteriorate. The phenolic resin component decreases the crosslinking rate and the degree of crosslinking of the oxidatively drying coating, which according to the present technical state can be used exclusively.

The best performing adhesion primers are solvent paints which usually contain polyvinyl butyral, phosphoric acid, pigments and phenolic resins. In the selection of pigments (this also includes fillers and extenders1, 20 have so far been referred to the concomitant use of chroma pigments, especially zinc chromate. Zinc chromate not only significantly improves corrosion protection, but also improves adhesion to the metallic surfaces, especially for aluminum and zinc.

At these surfaces, the enhancement of the adhesion is in the foreground, at the iron surfaces the corrosion protection.

However, chromium pigments have the disadvantage of being carcinogenic.

It is desirable to make adhesive primers which do not have the aforementioned disadvantages and which are useful, without causing discoloration in the coating paint, also enable application within the thermosetting lacquer structure and can be used without the simultaneous use of the carcinogenic chromate pigments . This is achieved in accordance with the invention with adhesive primers based on polyvinyl acetals dissolved in organic solvents and pigments, acid phosphorous compounds, synthetic resins and optionally additional additives which are characterized by having epoxy resins and synthetic resins. and / or esters of epoxide resins with aliphatic mono- or dicarboxylic acids, whose epoxide groups are reacted at least 80%, preferably at least 90%.

As solvents are conveniently low alcohols having up to 4 C atoms, such as methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, the esters of these alcohols with monocarboxylic acids, especially with acetic acid? glycol ethers such as ethylene glycol monomethyl ether or monoethyl ether, propylene glycol monomethyl ether or monoethyl ether or their esters with monocarboxylic acids, especially with acetic acid, ketones such as acetone, methyl ethyl ketone, diethyl ketone or aromatic hydrocarbons such as toluene, xylene, these solvents.

As polyvinyl acetals, e.g. polyvinylacetals of form, acetate, propionic, butyric, isobutyric and valeraldehyde and higher aldehydes of up to 10. Oatoms, especially polyvinyl butyrals or isobutyrals of different molecular size and different acetalization degree. The ratio of polyvinyl acetal to synthetic resin is generally between 4: 1 and 1: 4, preferably between 3; 1 and 1: 3.

As pigments, e.g. iron oxide red, rutile or anatase type titanium dioxide, soot, zinc phosphate, zinc oxide and aluminum zinc phosphates. As common additives, e.g. fillers or extenders such as talc, barium sulfate and pyrogenic silicic acid under consideration. Without affecting the adhesion and corrosion protection properties, chromate-containing pigments can be dispensed with. However, it is also possible to add these pigments.

As phosphorus compounds are suitable, e.g. the acidic esters of the various phosphoric acids, acidic phosphates, but preferably the orthophosphoric acid itself. These are usually added in amounts of 1 to 30%, preferably 1.5-20%, based on the binder proportion, i.e. resin + polyvinyl acetal. In application of the two-container adhesion primer, as defined below, with basic pigments, it is advisable not to increase the phosphoric acid content above 15%.

As the ether component of the ethers of epoxide resins 5, mono- and / or divalent phenols, e.g. the following, and furfuryl alcohol and, as an ester component in the esters of epoxide resins, as mentioned, at most dibasic carboxylic acids. The reaction with the underlying epoxide resins must be carried out extensively and the residual epoxide content 10 should be low. The epoxide numbers of the ether and the esters should generally not exceed 1.0, or better 0.5.

In particular, for the preparation of the ethers and esters, epoxy resins based on diphenylol alkanes, in particular diphenylol propane and / or methane and epihalohydrin, preferably epichlorohydrin, having molecular weights of 200 to 4000, preferably 300 to 2000, are used. phenol ethers of the epoxide resins in a conventional manner so as to react epoxide resin one with an amount of phenol at least equivalent to the amount of epoxide groups in the presence of a basic catalyst, e.g. alkali metal hydroxide, tertiary amine or triphenylphosphane at temperatures from room temperature to 200 ° C, preferably from 120 to 180 ° C, in melt or in solution. When working with tertiary amines as a catalyst, these can simultaneously have primary and / or 25 secondary amino functions, so that the catalyst is built into the resin. It is also possible to use low molecular weight epoxide resins, e.g. the diglycidyl ethers of diphenylol alkanes, with diphenylol alkanes and / or phenols by a one-step process, the molecular size of the final products being controlled through the mole ratios of the components. In order to form the ether with furfuryl alcohol, it is convenient to use finished epoxide resins and otherwise work under the same conditions as with phenols.

The preparation of the epoxide resin esters is carried out in a conventional manner, usually at 60-200 ° C, preferably at 100-170 ° C, by esterification of the aforementioned epoxide resins with monocarboxylic acids and / or dicarboxylic acids, which may also be olefinic. unsaturated, in solution or melt. Thus, it is convenient not to increase the amount of carboxylic acids above the amount needed for the complete esterification of the epoxide groups. For carrying out this reaction 5, the above catalysts may be present, but they should not be. These epoxide resin esters can be prepared a) of relatively high molecular weight or, as discussed in the reaction with phenols, low molecular weight epoxide resins, e.g. the di-glycidyl ethers of diphenylol alkanes and optionally an additional 10 diphenylol alkanes and b) carboxylic acids and / or carboxylic acid glycidyl esters. Thus, based on low molecular weight epoxide resins, the above catalysts must be present.

Advantageously, the lacquer contains one or more compounds having at least one phenolic OH group e.g.

15 in amounts from 0.02 to 4% by weight, preferably from 0.05 to 0.3% by weight, based on the solvent-free binder portion through which the corrosion resistance is improved.

As phenols can be used mono- and / or polyhydroxybenzenes, especially single-core, including, above all, monovalent phenols, such as the isomeric cresols or ethylphenols or the isomeric alkylphenols with 3-18 C atoms or recorsinol, hydroquinone, pyrocatechol or the isomeric trihydroxybenzene -ner. In particular, the use of phenol (hydroxybenzene) is preferred.

In the preparation of the epoxide resin phenol ethers under the concomitant use of monovalent phenols, the weight ratios can be selected so that the desired content of the free phenol adjusts by itself. However, after the derivative formation is completed, the free phenols can be added to the resin or to the varnish. It is very surprising that no discoloration of the free phenol coating varnish occurs.

The preparation of the adhesive primer itself is conveniently done by dissolving the polymers, synthetic resin and optionally the phenols in solvents and then incorporating pigments and optionally common additives. Preferably, the incorporation of the pigments occurs

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, DK 167771 B1 6 in the solution of synthetic resin. The phosphorous compound, after these working processes, is optionally added in admixture with some of the varnish components, preferably with the solvents used for dilution, or also immediately prior to use. In this case, a two-container adhesion primer is mentioned.

The metal surfaces to be protected, especially those of iron, chromium, zinc, tin or aluminum, are generally degreased prior to lacquering, without this being absolutely necessary. The foundation is excellent corrosion resistant, hard, adheres extremely well to the substrate and can be deformed together with it without any damage to it. In addition, the base members can be welded pore-free. These properties start to settle shortly after application 15 at ambient temperature.

All common varnishing systems can be used for overcoating. The adhesion primer does not penetrate through the lacquer. In particular, coatings based on varnishes are based on the following binders: oxidative curing alkyd resins, nitrocellulose (NC) and NC combinations, with isocyanate cross-linking acrylic and polyester resins, with polyamines or polyamidoamines cross-linking epoxide resins and vinyl chloride - blend polymers , eg. the above-mentioned, furthermore as thermosetting binders polyester, alkyd and acrylic resins in combination with urea and / or melamine resins and self-crosslinking acrylic resins. Nevertheless, a thermal finishing is not necessary for the development of the protective properties of the adhesive primer coat.

However, it is possible when the nature of the cover layer requires it. Neither 30 nor in this case any penetration occurs.

In the above and in the examples, parts (D) are parts by weight and percentages by weight.

35

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7 DK 167771 B1

Examples 1). In a reaction vessel equipped with a stirrer and thermometer, 507 D technical 4,4'-diphenylol-propane diglycidyl ether (epoxide equivalent weight 190,

5 average molecular weight 380, viscosity 22 Pa.s / 25 ° C), 152 D

4,4'-diphenylolpropane and 125D phenol are added to 0.24D dimethylaminopropylamine and heated to 140 ° C. At this temperature, stir for 8 hours. The starting mixture is then dissolved in 389 D n-butanol, 195 D isopropanol and 100 D toluene. The yield is quantitative. The resin solution has a solids content of 60.5% and a viscosity of 1200 mPa.s / 20 ° C. Free phenol content is 0.59%, epoxide number 0.13.

2). In an apparatus equipped with stirrer, thermometer and reflux, 264 D 'sononanoic acid glycyl ester, 304 D 4,41-diphenylol propane and ij are heated. D 4,4'-diphenylol-propane diglycidyl ether and 0.25 D dimethylaminopropylamine to 140 ° C and this temperature is maintained for 8 hours. Then, with cooling, 350 D of n-butanol is added. The yield is quantitative. The viscosity of the 70% solution is 6200 mPa.s / 20 ° C, 20 epoxide number 0.19.

Lacquer technical tests

With the resins of Examples 1 and 2 and three comparative lacquer systems according to the state of the art, 25 lacquer technical tests are carried out. The polyvinyl butyral has a softening range according to the "ring and ball method" (DIN ISO 4625) from 150 to 170 ° C, a density of approx. 1.1, a content of butyral groups from 83-86 equivalent%, of acetate groups of approx. 3 equivalent% and of alcohol groups from 11 to 14 equivalent%. The viscosity of Hoppier, DIN 53.015 is in 10% butanolic solution at 20 ° C between 90 and 150 mPa.s. For the comparison experiments, the following resins are used: I) in acid catalysis, hardenable phenolic resin, viscosity according to DIN 53.177 / 20 ° C 500-650 mPa.s, residue according to DIN 53.216 approx. 70%; 8O II) a curable, non-plasticized phenolic resin, viscosity according to DIN 53.177 / 20 ° C 190-300 mPa.s, residue according to DIN 53.216 approx. 70%;

III) the medium oil, non-drying alkyd resin with phthalic anhydride content of 32%, viscosity according to DIN 53.177 / 20 ° C

5 90-130 mPa.s, acid number according to DIN 53,402 peaks 10 and residue according to DIN 53.216 of approx. 80%; IV) non-plasticized urea resin, viscosity according to DIN 53.177 / 20 ° C 1000-1200 Pa.s, residue according to DIN 53.216 approx. 65%.

10 For comparison III, a mixture of 6.3 D is used

of resin III and 7.7 D of resin IV.

A B C D E

(Invention) (Comparison) 15 .............

Resin of Example 1 14.3

Resin of Example 2 - 14.3 -

Comparison I - 14.3

Comparison II - - - 14.3 20 Comparison III - - - - 14.0 20% polyvinylbutyralopl. 50 50 50 50 50

Talk IT extra 10 10 10 10 10

Iron oxide red 12 OM 6 66 6 6

Zinc phosphate ZP 10 10 10 10 10 10 25 Silicic acid HDK-H 15/10% 4 4 4 4 4

Diluent 30 30 30 30 30 H 2 PO 2 / n-Butanol 1: 2 4 4 4 4 4 30 Preparation of Adhesive Primers

The pigments and extenders are comminuted with the synthetic resin solutions in a fast-running agitator mill to a fineness of approx. lOyum. Then the polyvinylbutyral solution, the phosphoric acid / butanol mixture and the diluent are added.

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9 DK 167771 B1 Lubrication

The adhesion primers are sprayed at an outlet viscosity of approx. 20 DIN / s (DIN beaker 4 mm, DIN 53.211) with a spray gun with air spray on the test plates. The thickness of the dry film is 30-35 µm. The films are tested immediately for their drying speed} the other tests take place after 7 days storage at room temperature. The films are assessed on a subjective scale according to DIN 53.230, with the designation 0 meaning no change and the designation 5 being the 10 worst possible value. The resistance to water impact, the salt mist test and the drying speed are tested on iron substrates.

A B C D E

15 Results (Invention) (Comparison) Drying (DIN 53,150) Drying Grade 1 in minutes 78897

Adhesion (DIN 53.151) to iron 20 - "- aluntiniumO 0 2 3 2 -" - zinc 0 0 2 3 2

Water storage for 72 hours at room temp.O 0 03 0

Salt mist test (DIN 53.167) in ...

168 hours: 25 Bladder volume (DIN 53.209) 11345

Bladder size (DIN 53.209) 1 2 2 2 2

Rust (DIN 52.210) 11222

To determine the breakthrough of the cover lacquer 30, the iron test plates are sprayed after three days of storage with a room temperature crosslinking and a thermal crosslinking cover lacquer having the following composition, after a 10 minute deaeration time, the heat curing cover is burned for 30 minutes at 120 ° C. 35 with air circulation.

10 UK ID /// I bΊ o Tire lacquer crosslinking at room temperature Percentage of 55% alkyd resin solution in test gasoline (delivery form) 1) 60.0

Titanium dioxide EN 59 28.0 5 Ca-octoate, 4% Ca 1.1

Co-octoate, 6S Co 0.2

Pb-octoate, 24% Pb 0.4

Zr octoate, 6% Zr 0.8

Xylene / Test Gasoline 8: 2 9.5 10 ^ The intermediate oil, oxidative drying alkyd resin with 45% oil content and 27% phthalic anhydride, calculated on 100% resin; viscosity 400-550 mPa.s / 20 ° C; acid number Tinder 10.

Thermal cross-linking lacquer ....... Proportions - 60% alkyd resin solution in xylene 38.6

Titanium dioxide RN 59 32.0 3) 55% melamine resin solution in butanol / xylene 11/7 4) 65% urea resin solution in butanol 7.4 20

Ethyl lenglycol monoethyl ether lacetate 1.0

Xylene / Butanol 8: 2 9.8 100.0 25 2) Short oil, oxidative drying alkyd resin, oil content 42%, phthalic anhydride content 40%, calculated on 100% resin; viscosity 250-350 mPa.S / 20 ° C; acid numbers below 25.

3) non-plasticized, highly reactive melamine formaldehyde resin as 55% solution in isobutanol / xylene; viscosity 390-520 30 mPa.s / 20 ° C.

4) Non-plasticized urea resin as 65% solution in butanol; viscosity 3000-3600 mPa.s / 20 ° C.

The lacquers are lubricated with a dry layer thickness of 30 to 35 µm on the adhesion foundation and, for comparison, on a neutral glass plate. The drying speed is tested immediately.

After 10 days of storage at 23 ° C, the relative yellowing is assessed in comparison with the lacquer film on the glass plate. The gilding is assessed 2 hours after the burn-in.

Results: AB C D E Glass 5 (Invention) (Comparison) _

Oxidative drying 2h 2h 2.51 41 2.5h 2t (drying grade 1) (DIN 53,150)

Penetration 003 40 0 10 Thermal drying

Breakthrough 004 40 0 15 20 25 30 35

Claims (9)

2. Adhesive primers according to claim 1, characterized in that they contain orthophosphoric acid as a phosphorus compound. Adhesive primer paints according to claim 1 or 2, characterized in that, as ethers of epoxide resins, they contain ethers of epoxide resins with mono- and or divalent phenols or furfuryl alcohol. Adhesive primer coatings according to one or more of claims 1 to 3, characterized in that they contain polyvinyl butyral as polyvinyl acetal. Adhesive primer coatings according to one or more of claims 1 to 4, characterized in that the weight ratio of polyvinyl acetal to synthetic resin is between 4: 1 and 1: 4, preferably between 3: 1 and 1: 3. Adhesive primer coatings according to one or more of claims 1 to 5, characterized in that the content of acid phosphorus compounds ranges from 1 to 30% by weight, preferably from 1.5 to 20% by weight, based on the proportion of binder. Adhesive primer according to one or more of claims 1 to 6, characterized in that the pigments are chromate-free. Adhesive primer coatings according to one or more of claims 1 to 7, characterized in that they contain 0.02 to 3% by weight, preferably 0.05 to 3.0% by weight, based on the solvent-free binder portion, of at least one compound with at least one phenolic OH group, o Preferably phenol. Use of adhesion primer according to one or more of claims 1-8 for priming metal surfaces, especially of iron, zinc and aluminum. 5 10 15 20 25 30 35