DE2215630C3 - Use of aminophenyltrialkoxysilanes for surface treatment - Google Patents

Description

- CH ₂ -CH ₂ - 0-CH ₂ -CH ₃ grouping.

The present invention deals with the use of aminophenyltrialkoxysilanes on inorganic, oxidic and metallic surfaces as adhesion promoters for polymers or for corrosion protection.

It is known that the adhesion of thermosetting resins to inorganic, oxidic materials can be improved by treating the surfaces of these materials with an aminoalkyltrialkoxysilane treated (see. DE-PS 12 42 358). For some purposes, however, is the adhesion achieved with it not sufficient, especially if the laminates described in DE-PS 12 42 358 one exposed to prolonged exposure to warm water.

It is also known from DE-PS 11 71 235 ago that one can use the aminoalkyltrialkoxysilanes Surface of metals can protect against corrosion when these metals are in a liquid which is generally regarded as having a corrosive effect. About the anti-corrosion effect these silanes in relation to the atomospheric air and at elevated temperatures are described in this patent nothing said.

It has now been found that aminophenylalkoxysilanes of the general formula

Si— (

NHR

in which R stands for H or an alkyl radical with 1 to 4 carbon atoms and R 'stands for an alkyl or alkoxyalkyl radical having 1 to 10 carbon atoms for the surface treatment of inorganic, oxidic or metallic surfaces for the purpose of a subsequent coating with polymeric substances and / or as corrosion protection.

It has surprisingly been found that these aminophenylalkoxysilanes are more effective than the known ones Aminoalkylsilanes. This better effect was not to be expected, since in the case of the invention Aminoarylsilanes used only an exchange of the known aminoalkyl group by an aminophenyl group takes place.

ίο The oxidic and metallic surfaces that can be pretreated according to the invention include both mineral oxidic surfaces and those of synthetically manufactured products. Examples of mineral products are asbestos, mica, quartz, iron oxides. Examples of the other products include glass fibers, fiberglass, glass spheres, calcium carbonate, Fe ₂ O ₃

As metals come z. B. iron, zinc, aluminum, magnesium, copper and alloys that contain these metals as main components, e.g. B. Brass and bronze.

The polymers whose adhesion to the surfaces mentioned is improved according to the invention include natural and synthetic rubbers, polymerisation products such as PVC and polycondensation products such as epoxy resins or polyurethane resins and others. m.

The treatment of the surfaces with the silanes is expediently carried out in such a way that a solution is obtained the silanes are used in a suitable solvent. Water, alcohols, preferably C2 to Gt alcohols, ketones, such as acetone, Chlorinated hydrocarbons and aromatic hydrocarbons such as benzene, toluene, xylene, or gasoline be used. Mixtures of these solvents with one another can also be used. the Concentration of the solutions to be used depends on the dissolving power of the aminoarylsilanes in the concerned solvent. The effect according to the invention already occurs when using 0.05% by weight solutions. Preferably the amount of silane in the solution is between 0.1 and 1.7 % By weight, but quantities of up to 3.5% by weight and more can also be used.

The silane solutions are applied to the surfaces by known methods, such as. B. by Dipping, spraying, spraying, painting.

example 1

Glass fibers that have previously been subjected to heat cleaning are immersed in a mixture of equal parts by weight of water and ethanol containing 1% by weight of aminophenyltrimethoxysilane and then air-dried. The glass fibers treated in this way are then wetted with epoxy resin that has not yet hardened and then processed into a round bar test piece. The curing of the epoxy resin takes place through a three-hour temperature treatment of the test body at 130 ^° C.

The following table shows the test results that were obtained with glass fibers that a) contain no adhesion promoter, b) as adhesion promoter y-aminopropyltriethoxysilane and c) p-aminophenyltrimethoxysilane contained. In each case, the bending

b5 tests tested with a freshly cured Material obtained and with samples exposed to boiling water for 72 hours after curing and examined wet.

% Silane in the solution

Biegefestig- Biegekelt dry strength N / cm ² moist

N / cm ²

a) O sample (0% silane) 90,000 35,000

b) 1% y-aminopropyltri-

ethoxysilane 94 000 86 500

c) 1% aminophenyltrimeth-

oxisilan 118000 Q0 000

10

Evaluation of the results shows that the Adhesion glass / resin both before the water storage and afterwards with the above-mentioned connection showed far better flexural strength values.

Example 2

Thin, degreased copper and brass strips measuring 5 × 10 cm were dipped into a 2% solution of aminophenyltrimethoxysilane in i-propanol and dried in the air. These samples were then stored in an oven ^{at 150 ° C. for 3 hours.}

After cooling, a comparison of these treated samples with untreated samples, which had also been ^{stored for three hours at 150 °} C. in an oven, showed that the treated samples had retained the Cu color, while the untreated samples were black. The surface treatment according to the invention thus resulted in good protection against corrosion.

Example 3

Degreased iron sheet strips were treated with a 2% strength benzene solution of an aminophenyltriethoxysilane and ^{dried in the oven at 120 °} C. for minutes. The iron sheets pretreated in this way were then coated with a PVC varnish and this was cured in a drying cabinet.

The test was carried out by Erichsen cupping with cross-cut and showed 100% adhesion while untreated comparison samples show only slight adhesion between PVC and iron surface.

Example 4

A degreased iron plate was treated with a 10% gasoline solution of an N-methylaminophenyltrimethoxysilane treated and air dried. Then this pretreated panel is covered with polyurethane resin coated and this resin is then cured

The investigation took place through the Erichsen detention tester and showed an improvement in the iron / polyurethane adhesion of about 1.50% compared to a Comparison sample without silane as adhesion promoter.

Example 5

Glass fibers that have previously been subjected to heat cleaning are immersed in a mixture of 90 parts by weight of water and 10 parts by weight of ethoxyethanol (ethyl glycol), which contains 1% by weight of aminophenyltriethoxyethoxysilane, and then air-dried Thereafter, the thus treated glass fibers be wetted with not yet cured epoxy resins and then to a curing of the epoxy resin Rundstabprüfkörper processes carried out by a 3-hour heat treatment of the specimen at 130 ⁰ C.

The following table shows the test results that were obtained with glass fibers that a) contain no adhesion promoter, b) the well-known y-aminopropyltriäthoxiäthoxisilan as an adhesion promoter and c) p-Aminophenyltriäthoxiäthoxisilan contained. There were each tested the flexural strengths that were obtained with a freshly cured material and with Samples that had been exposed to boiling water for 52 hours after curing and examined while moist became.

% Silane in the solution

Flexural strength (N / cm ² )
dry 72 h boiling test

a) O sample

b) 1% γ-aminopropyltriethoxyethoxysilane

c) 1% aminophenyltriethoxyethoxysilane

90,000 35,000

97,000 72,000

104,000 91,000

The evaluation of the results shows that the adhesion glass / resin both before the water storage as even after immersion in water with the compound used according to the invention, far better flexural strength values resulted as with known Aminoalkyltrialkoxisilanen.

Claims (1)

Claim: Use of aminophenyltrialkoxisilanes of the general formula -Si (OR '): NHR in which R stands for H or an alkyl radical having 1 to 4 carbon atoms and R 'stands for an alkyl or alkoxyalkyl radical with 1 to ί 0 carbon atoms, as an adhesion promoter for polymer layers and / or as corrosion protection on inorganic, oxidic or metallic surfaces. The radical R 'in the above formula can be both an alkyl radical and an alkoxyalkyl radical, such as. B. the -CH ₂ -O-CH ₂ -CH ₃ -
or the