SE438610B - PROCEDURE FOR THE COATING OF CURRENT ORGANOPOLYSILOXAN - Google Patents

Description

79o9§o7-3 organopolysiloxane with coating agents, the process according to the invention has, for example, the advantage that it can be carried out with a larger number of types of crosslinked organopolysiloxanes and / or coating agents and / or with more readily available organosilicon compounds.

The present invention relates to a process for coating crosslinked organopolysiloxane with coating agent, which is characterized in that at least one silane, which per molecule contains an amino group bound over carbon to silicon and at least one * bound over oxygen to silicon, monovalent, optionally with amino or alkoxy group substituted hydrocarbon residue, and / or partial hydrolyzate of such silane prior to coating the crosslinked organopolysiloxane with coating agent is applied to the crosslinked organopolysiloxane or the portion of the surface of the crosslinked organopolysiloxane to be coated with coating agent and / or mixed with the coating agent before the crosslinked organopolysiloxane is coated therewith.

Admittedly, silanes of the type used according to the invention, when used as mixing constituents, in the case of exclusion of water which can be stored and when water is admitted at room temperature to elastomers, can be crosslinkable based on diorganopolysiloxanes (cf., for example, German Official Journal DE-OS 19 64 502, publication date, April 26, 1973, Wacker-Chemie GmbH) an improvement in the adhesiveness of the elastomers made from such pulps on substrates on which the elastomers were obtained, but does not improve the adhesion of coatings produced on loads of such pulps.

As crosslinked organopolysiloxanes, any crosslinked organopolysiloxanes can be used in the process of the invention. Those with the exclusion of water-storable, at access to water at room temperature to elastomeric crosslinking or curing compositions based on diorganopolysiloxane are particularly preferred because it is often desired to coat elastomers of such compositions, e.g. seals of f 7909907-3 wooden windows or of joints on ship decks consisting of such elastomers, with coatings.

In the preparation of water-storable masses based on the exclusion of water and on the access of water to elastomer-based elastomers based on diorganopolysiloxane, from which preferred crosslinked organopolysiloxanes can be produced within the invention, arbitrary amounts can be used as before. materials which have also previously been used for the preparation of water-exclusion-storable, at the access of water at room temperature to elastomeric crosslinking compositions by mixing at least one silicon compound with at least three silicon-bonded, hydrolysable groups with diorganopolysiloxane, which show condensation end-prone end groups and any additional substances, such as fillers, for example gas-phase fumed silica or calcium carbonate, condensation catalysts, for example dibutyltin dilaurate, plasticizers, for example at room temperature liquid dimethylpolysiloxane, which is end-blocked with trimethylsilox lyoxyalkylene glycol.

Examples of silicon compounds which have at least three silicon-bonded hydrolysable groups which can be used in such a preparation are silanes of the general formula Rasiz4a I in which R represents the same or different, monovalent, optionally substituted hydrocarbon groups and Z represents the same or different hydrolysable groups and a means 0 or 1, as well as partial hydrolysates which have 2 to 10 silicon atoms per molecule.

Examples of the hydrocarbon radical R are alkyl radicals such as methyl, ethyl, n-propyl and isopropyl group and octadecyl group, alkenyl groups such as vinyl and allyl groups, cycloaliphatic hydrocarbon groups such as cyclopentyl and cyclohexyl group and methylcyclohexyl and cyclohexyl group xenyl group, aralkyl group such as benzyl, ß-phenyl and ß-phenylpropyl group, and alkaryl groups, 1,., _.-, ._........_.._......... .... í .._....__.. --- ..., 7909907-3 such as tolyl groups.

As the substituted hydrocarbon groups R, haloalkyl groups such as chlorophenyl and bromophenyl groups are preferred, as well as cyanoalkyl groups such as E -cyanethyl group.

Particularly due to easier availability, methyl group is preferred as group R.

Examples of hydrolysable groups Z are acyloxy groups (-OOCR1), optionally substituted hydrocarbon oxy groups (-OR1), aminoxy groups (-ONRÉ), amino groups (eg -NRÉ), acylamino groups (eg -NR1COR1), oxime groups ( eg -ON = CRš) and phosphate groups [¥ Oï (ORl) 27.

In these formulas, R 1 represents the same or different, monovalent, optionally substituted hydrocarbon groups. However, it is known to those skilled in the art that at least in some of the formulas given above, at least one R1 may be hydrogen.

Examples of acyloxy groups are formyloxy and acetoxy groups.

Examples of hydrocarbon oxy groups are methoxy, ethoxy and isopropenyloxy groups.

An example of a substituted hydrocarbon oxy group is methoxyethylene oxy group.

Examples of aminoxy groups are dimethylaminoxy and diethylamine oxy group.

Examples of amino groups are n-butylamino, sec-butylamino and cyclohexylamino group.

An example of an acylamino group is the benzoylamino group. 79099 07-3 Examples of oxime groups are acetaldoxime, acetone oxime and 2-butanone oxime group.

An example of a phosphate group is di-n-butyl phosphate group.

Further examples of crosslinked organopolysiloxanes which can be coated by the process according to the invention are elastomers or resinous products of so-called "two-component system", which may consist, for example, of dimethylsiloxane, which in each terminal unit has a Si-bonded hydroxyl group, as well as fillers in a package and a mixture of polyethylsilicate and dibutyltin dilaurate in an additional package, and which gives elastomers.

Other examples of crosslinked organopolysiloxanes which can be coated by the process according to the invention are elastomers or resinous products which are prepared from organopolysiloxane in heat, usually at temperatures above 100 DEG C., by condensation or radical formation, for example with dicumyl peroxide.

Finally, examples of crosslinked organopolysiloxanes which can be coated by the process of the invention are also elastomers or resinous products which can be prepared by attaching Si-bonded hydrogen atoms from organopolysiloxanes containing such hydrogen atoms to aliphatic multiple bonds in organopolysiloxanes which contains such multiple bonds, in the presence of catalysts, which favor this deposition, for example platinum compound.

The silanes which are preferred, for example because they give the best results, and which per molecule contain at least one amino group bound over carbon to silicon and at least one hydrocarbon-bonded monovalent, optionally substituted hydrocarbon group optionally substituted by amino or alkoxy group, defined by the general formula - 2. R 2 N (cH 2) m Ya (cH 2) m 7bs 1 (oR) CR 4 -b-c. 7909907-5 6 In this formula, R and a have the meanings given above.

Furthermore: R 2 means hydrogen and / or equal or different monovalent hydrocarbon groups, R 3 equal or different monovalent, optionally substituted with an amino or alkoxy group, Y oxygen or NR 2, b and c, each, the integers 1, 2 or 3, the sum of b + c is not more than 4 and m the same or different integers in the range 1 to 10.

The above examples of hydrocarbon groups R apply, with the exception of vinyl group, to the full extent also to hydrocarbon groups R. Additional examples of hydrocarbon groups R are n-butyb, tert-buty, 3,5,5-1 = rimethylcyclo <hexyl- and 2,3,4-triethylcyclohexyl group. Preferably, however, at least one R 2 is hydrogen.

Examples of groups R 3 are alkyl groups having 1 to 6 carbon atoms, for example methyl, ethyl and n-butyl group and sec. And tert-butyl group, aminoalkyl groups such as β-aminoethyl group, alkoxyalkyl groups such as β-methoxyethyl group, cycloalkyl groups, such as cyclohexyl group, aryl groups such as phenyl group and aralkyl groups such as benzyl group.

Examples of silanes of the above formula are those of the formula CH 3 Si (OCH 2 CH 2 NH 2) 2 (CH 2) 3 O (CH 2) 2 NH 2, (CH 3 O) 3 Si (CH 2) 3 NH (CH 2) 2 NH 2, H 2 N (CH 2) 2 O (CH 2) 3 Si ( OCH 2 CH 2 NH 2) 3 OCh H 2 N (CH 0 (CH 2) 3 Si (OC 2 H 5) 3 2) 2 and the compounds named N-β -aminoethyl-β-aminopropyltriethoxysilane, β-aminoethyltriethoxysilane, N-fi -aminoethyl-α-amilopylamethylthrite .

The use of silane, which per molecule contains an amino group bonded to carbon to silicon and at least one monohydric bond bound to oxygen to monosilicon, optionally substituted by an amino or alkoxy group, is preferred before the use of partial hydrolyzate of such silane.

However, if part hydrolyzate of silane is used, which contains per molecule at least one amino group bonded over carbon to silicon and at least one hydrocarbon-bonded, monovalent, optionally substituted hydrocarbon group optionally with an amino or alkoxy group, it is suitable that this partial hydrolyzate contains contains a maximum of 10 silicon atoms per molecule. If desired, mixtures of different silanes, which in each molecule contain at least one amino group bound to carbon to silicon and at least one monovalent, optionally substituted hydrocarbon-bonded to silicon, may be used.

Since in this way a smaller amount of organosilicon compound used according to the invention for improving the adhesion of coatings on crosslinked organopolysiloxane, which contains at least one amino group bound over carbon to silicon, is required, it is convenient to apply such organosilicon before coating crosslinked organopolysiloxane with coating agents. compounding on the crosslinked organopolysiloxane and on the part of the surface of crosslinked organopolysiloxane intended for coating and not mixing the organic silicon compound with coating agents. For this application, it may be appropriate to use silane, which per molecule contains at least one amino group bound over carbon to silicon and at least one hydrocarbon bound to silicon, monovalent, optionally substituted by an amino or alkoxy group hydrocarbon group, and / or delhydroly - set of such silane in solvent diluted form. For this dilution one can use, for example, aliphatic hydrocarbons, such as alkanes with a boiling point in the range 120 - 180 ° C 79099o7 + s at 1 bar, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone, alcohols such as methanol or isopropanol and / or chlorohydrocarbons, such as trichlorethylene. The proportion of organosilicon compound used according to the invention, which has at least one amino group bound over carbon to silicon, calculated on the total weight of such organosilicon compound and solvent can, for example, amount to 1-90% by weight.

The application of the organosilicon compound used according to the invention to improve the adhesion of coatings to crosslinked organopolysiloxane which contains at least one amino group bonded over carbon to silicon on the crosslinked organopolysiloxane and the part of the surface of crosslinked organopolysiloxane can be intended for coating with coating agent. carried out by spraying, coating, rolling or dipping. Prior to this application, simultaneously with this application and in this case separately or in admixture with the organosilicon compound used according to the invention, which contains at least one amino group, and / or after this application, the crosslinked organopolysiloxane or the part of the surface of the coating agent intended for coating crosslinked organopolysiloxane at least one condensation or hydrolysis catalyst is applied.

Examples of condensation or hydrolysis catalysts are metal carboxylic acid salts or organometallic carboxylic acid salts of metals within the electrometric voltage chain from lead to manganese (cf. Handbook of Chemistry and Physics, 31st edition, Cleveland, Ohio, 1949, page 1465), in particular of tin, such as dibutyl, dibutyltin diacetate, a mixture of dibutyltin diacylates, wherein the acylate groups are derived from carboxylic acids containing 9 to 11 carbon atoms per molecule, the carboxyl groups of at least 90% by weight of the acids being bonded to a tertiary carbon atom, dibutyltin dannethioethoethoxethoxane, for example iron octoate, lead octoate, lead laurate and cobalt naphthenate, titanium esters, such as tetrabutyl titanate, amines such as n-hexylamine and amine salts such as n-hexylamine hydrochloride and n-butylamine acetate.

The coating compositions used within the scope of the invention may be paints, aqueous dispersions or glazes, for example those based on alkyl resin, polyurethane, or starting materials for polyurethane, nitrocellulose, epoxide, polyester or polyvinyl chloride or mixed polymers of polyvinyl chloride, which are usually dissolved in organic solvents, or those based on acrylic resin, polyvinyl acetate or mixed polymers of polyvinyl acetate and / or styrene, such as polystyrene acrylate, commonly used as aqueous dispersions.

If according to the invention for improving the adhesion of coating to crosslinked organopolysiloxane used organosilicon compound containing an amino group bonded over carbon to silicon is added to the coating agent, the amount of such organosilicon compound preferably amounts to 0.1 to 10% by weight of total organosilicon compound, calculated on of coating agents and organosilicon compound.

In the following, all information regarding parts and percentages refers to the weight, unless otherwise stated.

The crosslinked organopolysiloxanes used in the following examples, namely organopolysiloxane elastomers, are prepared as follows: Elast A A mixture of 120 parts of a dimethylpolysiloxane, which in each terminal unit has a Si-bonded hydroxyl group having a viscosity of 80,000 mPa.s at 25 ° C. and 80 parts of a dimethylsiloxy group end-blocked dimethylpolysiloxane having a viscosity of 35 mPa.s at 25 ° C and 8 parts of a polyoxyalkylene glycol of 40% by weight ethylene oxide and 60% by weight propylene oxide having an average molecular weight of 3400 are mixed with 2 parts of a mixture mole of methyl tris- (butanone-2-oxime) -silane and 1 mole of methyl tris- (cyclohexylamino) -silane and 2.4 parts of silane of the formula (cH30) 3si (C112) 3NH (cnz) ZNHZ I the mixture thus obtained is then mixed with 180 parts of calcium carbonate whose particles are coated or coated with 3% of stearic acid and 16 parts of pyrogenically produced gas phase silica with an area of 150 m2 / g and finally 0.4 parts of dibutyltin dilaurate. The mass thus obtainable, excluding water-storable mass, is exposed in the form of a layer with a thickness of about 5 mm on a flat surface at room temperature for the action of water vapor present in the air and is thereby crosslinked to an elastomer, which was used 7 days after the spread of the mass on the substrate.

Elast B 100 parts of a trimethylsiloxy groups end-blocked diorganosiloxane of 99.93 mole percent dimethylsiloxane units and 0.07 mole percent vinylmethylsiloxane units having a viscosity of approx. 5. 106 mPa.s at 25 ° C are first mixed with 7 parts of a dimethylpolysiloxane, which in each terminal unit has a Si-bonded hydroxyl group, with a viscosity of approx. 40 mPa.s at 25 ° C, and 40 parts of pyrogenic gas phase produced silica with a surface area of 200 m2 / g and then with 1 part 95% dicumyl peroxide.

The mixture thus obtained is heated in the form of a plate for 15 minutes to 165 ° C and for 4 hours to 200 ° C and is crosslinked in this way to an elastomer.

Example gel 1 On parts of the surface of elastomer A, a solution of 50 parts of silane of the formula (CHBO) 3 Si (CH 2) 3 NH (CH 2) 2 NH-I 2, 50 parts of toluene and 5 parts of tetra-n-butyl titanate is applied. The solution 7909907 ~ s ll is allowed to dry for one hour at room temperature. It is then applied to the parts of the surface of elastomer A on which the silane has been applied, as a coating agent in a commercially available varnish based on alkyl resin (Ducohncqp Glanzcolor grau DG 704, Fa. Hermann Wiederhold Lackfabrik, 4010 Hilden, BRD) and as a coating. commercially available wood acid based on alkyl resin (Tixoton-Holz-Lasur, nut brown, "Meisterpreis", "Tixoton" and "Meisterpreis" are registered trademarks, F. Spangenberg, 4010 Hilden, BRD) and as a coating agent 3 a commercially available two-component polyurethane lacquer (Efdedur KRO-423 + Efdedur HU 7 in the blend ratio 4: 1, "Efdedur" is a registered trademark, Fa. Emil Frei, 7715 Bräunligen-Döggingen, BRD), and as a coating agent 4 a commercially available white paint based on an aqueous dispersion of a mixed polymer of styrene and vinyl acetate (Fa. Wacker-Chemie GmbH, 8000 Munich, BRD). All 4 coatings are opaque and flow out without interference.

Example 2 The procedure described in Example 1 is repeated with the difference that instead of elastomer A, elastomer B is used. All 4 coatings are opaque and flow out without disturbances.

Comparative experiment (a) The procedure described in Example 1 is repeated with the difference that no pre-treatment of the surface of the elastomer is carried out before the coating agent is applied. The smudge of the paint shows disturbances.

Comparative experiment (b) The procedure described in Example 2 is repeated with the difference that before the application of the coating agent no pre-treatment of the surface of the elastomer is carried out. Disruptions of the outflow are observed.

After one month, a square with a side length of 2.54 cm is cut with a razor into 100 equal squares, each with an area of 6.45 mmz. A contact adhesive tape is pressed against the lattice thus obtained 1909907-3 '12, which is then slowly peeled off again at an angle of about 300. The amount of small squares remaining on the elastomer gives the percentage value of the retention of the coating. The retention values of at least 95% correspond to very good adhesion, retention values of at most 65% correspond to poor adhesion. The average results of different measurements are given in the following table: Table Examples resp. % retention of coating agent comparison - '- attempt l 2 3 4 l _' 95 l00 99 99 2 'l00 100 IDO 100 (a) z 2 0 o (b) 4 0 5 0

Claims (3)

IB 7909907-3 PATENT REQUIREMENTS 1. A process for coating crosslinked organopolysiloxane with a coating agent, characterized in that at least one silane, which per molecule contains at least one amino group bound over carbon to silicon and at least one monovalent bound over oxygen to silicon, optionally with an amino acid or alkoxy group substituted hydrocarbon group, and / or partial hydrolyzate of such silane prior to the coating of the crosslinked organopolysiloxane with coating agent is applied to the crosslinked organopolysiloxane or the part of the surface of crosslinked organopolysiloxane or / or polysiloxane intended for coating with the coating agent with the coating agent before the crosslinked organopolysiloxane is coated therewith. 2. A process according to claim 1, characterized in that as silane, which contains per molecule at least one amino group bonded over carbon to silicon and at least one hydrocarbon bonded over silicon, monovalent, optionally substituted by an amino or alkoxy group hydrocarbon group those of the general formula were used 2.. [Rzwwn fi mya (cH2) m] bs1 (oR) cn4_b_ci in which R represents equal or different, monovalent, optionally substituted hydrocarbon groups, R2 represents hydrogen and / or equal or different monovalent, optionally substituted hydrocarbon groups, R3 means equal or different, monovalent, optionally substituted by an amino or alkoxy group hydrocarbon groups, Y represents oxygen or NR 2, a is 0 or 1, b and c each have the integer value 1, 2 or 3, the sum of b + c being at most 4 and m representing equal to or different whole numbers in the range from l - 10. ' at 7909907-3 W 3. A process according to claim 1 or 2, characterized in that a condensation or hydrolysis catalyst is also used.