DE2734106A1 - Ice-repellent paints for aircraft, ships, etc. - contg. basic polysiloxane(s) or their fatty acid salts as additives - Google Patents

Abstract

The paints may be based on chlorinated or cyclised rubber, vinyl polymers, epoxy-, polyurethane-, or phenolic-resins, and are pref. air-drying paints, e.g. oil paints, esp. alkyd resin paints. The additives are pref. basic methyl polysiloxanes, contg. 5-25 Si atoms. The basic gp. is pref. amino, attached to Si through a -(CH2)n- link (in which n is 2, 3 or pref. 1), and there are pref. 2-3 basic gps. per molecule. The basic gp. is perf. secondary, esp. a cyclohexylamine gp. Used for top coats on ships' superstructures, aircraft and radio equipment. Adhesion and accumulation of ice are substantially reduced, without effect on other properties.

Description

273A106

Bayer Aktiengesellschaft

Central area of patents, trademarks and licenses

5090 Leverkusen, Bayerwerk

G / Rz (Pv) Ice-repellent coatings 27 JnIi 1977

The icing of painted surfaces is annoying, e.g. for ship superstructures. This is why paints are of interest on which ice adheres so little that it falls off by itself or can be easily removed. Layers of ice that grow on conventional paint surfaces adhere so well that ship superstructures, transmission systems or aircraft parts keep icing up under appropriate climatic conditions. Such layers of ice on conventional paint surfaces are difficult to remove.

It is known that cellulosic plastics become ice-repellent by incorporating about 30% by weight of diols such as butanediol equip. This material is not suitable for painting.

The invention relates to the use of basic polysiloxanes and / or their fatty acid salts as an additive to paints. These additives reduce the ice adhesion quite considerably without the to impair other properties.

In principle, the paints are pigmented and unpigmented, both physically drying coatings, e.g. based on of Pergut, cyclo-rubber, chlorinated rubber, vinyl polymers, as well as single or multi-component reactive coatings such as epoxy, Polyurethane or phenolic resin paints are suitable. Preferably, however, air-drying paints such as oil paints, especially alkyd resin paints, used.

As to be used for salt formation with the basic polysiloxanes Fatty acids are preferably aliphatic, long-chain fatty acids with 1-40 carbon atoms which are liquid at room temperature and fatty acid mixtures, for example the natural, saturated

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th and / or mostly unsaturated fatty acids or those. Oligomerization products

such as the so-called dimer acids, oil of oil, tall oil, soybean oil, linseed oil, rapeseed oil, coconut oil, peanut oil, tung oil, castor oil or Wood oil fatty acids and similar products.

Oleic acid should be mentioned here as a preferred fatty acid to be used for salt formation.

The basic polysiloxanes are methyl- and phenyl-containing Polysiloxanes preferably use basic methylpolysiloxanes. These can be linear or branched. They should contain more than 2 Si atoms in the molecule, preferably they contain 5-25 Si atoms.

The basic group preferably consists of an amino group and is connected to the next Si atom via a (CH ₂ ^ grouping, where η is 1, 2 or 3, but preferably η is 1. Per mole of polysiloxane should be at least one , preferably 2-3 basic groups.

The amino group can be secondary or tertiary. Suitable substituents on the amino nitrogen, in addition to the CH ₂ bridge to the next Si atom, are preferably aliphatic or cycloaliphatic radicals in addition to hydrogen. The basic group is preferably a cyclohexylamine radical and is secondary.

The production of the aminopolysiloxanes to be used is known and is usually carried out by processes such as those used, for example in U.S. Patents 3,658,864 or 3,657,303 are described.

The polysiloxanes containing amino groups are formed by reaction of polysiloxanes containing chloromethyl groups with amines such as cyclohexylamine. The chloromethyl groups Polysiloxanes for their part are easily accessible in a manner known per se by direct cohydrolysis of, for example Mixtures of chlorinethyl-dimethylchlorosilane and dimethyldichlorosilane and subsequent equilibration, the ratio between chloromethylsimethylchlorosilane and dimethyldichlorosilane is chosen depending on the desired molecular weight.

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For example, a mixture of chloromethyldimethylchlorosilane and dimethyldichlorosilane is introduced into excess ice water to produce a polysiloxane containing amino groups. After about 2 hours, the organic phase is separated off, neutralized with potassium hydrogen carbonate, washed with more water and dried over sodium sulfate. To equilibrate the siloxane is mixed with acidic about 3 wt .- # bleaching earth and heated for 5 hours at 150 ⁰ C. It is filtered off and does present the equilibrated chloromethyl group-containing polysiloxane. The chloromethylpolysiloxane is then slowly added dropwise at 100.degree. C. into an amount, based on chloromethyl groups, about 10 times the molar amount of cyclohexylamine. The mixture is stirred at 100 ^° C. for a further 2 hours. It is allowed to cool and ^{the salt is filtered off at 20 °} C., then the excess cyclohexylamine is distilled off in vacuo. The desired polysiloxane having terminal amino groups remains.

By using chloromethyl-methyl-dichlorosilane and optionally trimethylchlorosilane in the cohydrolysis if desired, amino groups are incorporated in the siloxane chain or compounds are obtained which only have pendant amino groups (complete replacement of chloromethyl-dimethyl-chlorosilane by trimethylchlorosilane with simultaneous use of chloromethyl-methyl-dichlorosilane).

The salt formation between the basic polysiloxane and the optionally used fatty acid is carried out by simply mixing the components (in the paint itself or separately), whereby compliance with stoichiometric ratios is not necessary, ie it can easily be a stoichiometric deficit or excess of one of the components are used. Mixtures of the basic polysiloxane and, based on the total weight of the mixture, 0.1 to 90 % fatty acid, in particular about 50 % fatty acid, are preferably used in the application.

The basic polysiloxanes themselves or their fatty acid mixtures should be used in the paints according to the invention, based on solids weight, in amounts of up to 6% by weight of Ji Le A 18 277 - 3 -

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be included. Of course, in individual cases larger amounts can also be used, but since the effectiveness of the additives according to the invention is very good, only 0.2-2.5% by weight are preferably used.

In the following, the subject matter of the invention will be explained by way of example. The parts and percentages given relate to weight, unless otherwise stated.

A strong steel plate provided with the respective coating is used as a test area. On the plate A stainless steel tube is placed in the center and with soft silicone cement on the outer jacket against the test surface sealed. Then the pipe is partially filled with a constant amount of water and placed in the cold chamber frozen.

Steel plate: approx. 1 cm 10 cm χ 10 cm Pipe section: 0 7.1 cm Filling quantity: 200 cm ³ Test area 39.6 cm ² After freezing, the coated in the cold chamber

Base plate fixed on a turntable, which is provided with a lever for power transmission, in order to be able to measure the torque during the shear test (lever length adjustable). At the same time, the frozen water column fixed by a locking lever that engages in two grooves in the attached pipe socket. A shell is attached to the rotary lever via a cord guide into which lead shot is now entered until the frozen water column is removed from the coating to be tested releases and the power lever hits a locking mark.

The following paints were used as examples for the tests:

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, 3 H

Varnish I; commercial phenolic resin varnish

Lacquer II: commercially available, air-drying, weatherproof white lacquer based on alkyd resin

Lacquer III: commercially available, weatherproof clear lacquer based on alkyd resin.

As the basic polysiloxanes, the following have been exemplified Types are used, which one can think of as being made up of siloxane building blocks of the specified type:

^CH

M · - -O ₁₇₂ -Si CH

CH ₃

D ¹ - -0-Si-

CH ₂ -NH

T -

CH,
ι · *
D - -Si-O- CH ₃

Polysiloxane A: M ' ₂ D ₅ linear

B: M ' ₂ D _{10 llnear}

C: M ¹ ₂ D ₂₀ linear

D: TD ₁₅ M ¹ ₃ branched E: M ¹ ₂ D ¹ D ₁₅ segmented

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The following fatty acids were used as examples: Fatty acid O: oleic acid

P: Esters of oleic acid and ricinoleic acid (molar ratio 1: 1) Q: ricinoleic acid

__ _ _Ί R: Linoleic acid table

at
game
No. Recipe (parts by weight) What
ser
Type Measuring
temp.
⁰ C Turn
moment
(kpm) 1 I (100) 1 -30 5.0 2 I (98); D (1); 0 (1) 1 -30 1.9 3 III (100) d -30 6.5 4th III (100) d -10 6.0 5 III (100) 1 -30 5.2 6th III (100) 1 -10 1.3 7th III (99); A (1) 1 -30 1.8 8th III (99); B (1) 1 -30 1.2 9 III (99); C (1) 1 -30 0.9 10 III (99); D (1) 1 -30 0.8 11 III (99); E (1) 1 -30 0.6 12th II (100) d -10 6.5 13th II (99); B (0.5); 0 (0.5) d -10 2.4 14th II (98); B (1); 0 (1) d -10 1.2 15th II (96); B (1.5); L (1.5) 1 -30 1.7 16 II (100) 1 -30 5.1 17th II (100) sprayed with B (1) + 0 (1)
then wiped off 1 -30 2.0 18th III (99); 0 (0.5); A (0.5) d -30 1.2 19th III (99); 0 (0.5); B (0.5) d -30 1.2 20th III (99); 0 (0.5); C (0.5) d -30 1.0 21 III (99); 0 (0.5); D (0.5) d -30 1.1 22nd III (99); 0 (0.5); E (0.5) d -30 1.2 23 III (99); D (0.5); P (0.5) d -30 0.9 24 III (99); D (0.5); Q (0.5) d -30 1.0 25th III (99); D (0.5); R (0.5) d -30 1.0 26th III (99); Butanediol (1) d -10 5.9 27 III (99); D (1) d -10 1.8 28 III (99); D (0.5); 0 (0.5) d -10 1.6

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Because the adhesion of salt water ice to painted surfaces is less than that of tap water or distilled water Water, the tests were carried out with distilled (■ d) and tap water (■ 1) in order to create more difficult conditions and the ice deposits that often occur in practice due to the impact of cold surfaces To better correspond to precipitation or fog or condensation ice.

The test specimens were coated with the paint, which may have been provided with the additives, after thorough cleaning, the coatings were then allowed to settle for about 7 days, and the test was then carried out. The freezing times took about 3 hours.

The measured values obtained are in the attached table together with zero tests listed under the serial numbers 1-28.

It is clear in all cases that even very small amounts of the additives according to the invention are added Significantly lower the ice adhesion on the paint surface.

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Claims (1)

Claim: Use of basic polysiloxanes and / or their fatty acid salts as an additive to paints. Le A 18 277 - 8 - 809886/0 OPKiIHAL / N8PECTED