Aqueous siloxane emulsions and their use.

From EP-A-0068671, published 5. January 1983, Dow Corning Limited, aqueous compositions are known which contain salt of water-soluble organic or inorganic acid and organopolysiloxane which, in addition to other siloxane units, contains those siloxane units which have SiC-linked radicals with basic nitrogen, a silicon compound soluble in such salt, such as Methyltrimethoxysilan or a partial hydrolyzate of such a silane, and water-soluble solvent.

The subject of the as yet unpublished German patent application P 34 47 636.9 are compositions which, when diluted with water, give transparent compositions which, as essential constituents,<ul id="ul0001" list-style="none"><li>(^A) Salt of water-soluble organic or inorganic acid and polysiloxane which, in addition to other siloxane units, contains those siloxane units which have monovalent, SiC-bonded radicals with basic nitrogen in amounts of at least 0.5% by weight of basic nitrogen, based on the weight of this polysiloxane, and</li><li>(B) organic silicon compound with basic nitrogen in amounts of 0 to 0.5 percent by weight, based on the weight of such organic silicon compound, and at least if component (B) does not contain at least 0.1 part per part by weight of component (A) from at least one organic silicon compound with a molecular weight of at most 600 g / mol,</li><li>(C) organic solvent which at 20 ° C and 1020 hPa (abs.) Is at most one part by weight soluble in 100 parts by weight of water and free of halogen atoms, with the exception of octanols and free of water-soluble solvents or octanols or such solvents or Contain octanols in amounts of at most 5 percent by weight, based on the weight of components (A).</li></ul>

Component (B) can be organopolysiloxane with aliphatic radicals bonded to silicon via oxygen and having a molecular weight of about 600 g / mol.

It is an object of the invention to provide aqueous emulsions of organopolysiloxane with aliphatic radicals bonded to silicon via oxygen and having a molecular weight of at least 620 g / mol, which can be free of organic solvent which at 20 ° C. and 1020 hPa (abs.) At most one part by weight is soluble in 100 parts by weight of water and is free of halogen atoms that can be stored for a very long time without segregation, when used as an impregnating agent, for example of building materials, penetrate particularly deeply into the materials to be impregnated, are particularly well compatible with other resins, dry to clear films and thereby crosslink to a sufficient extent, the films thus obtained being particularly water-resistant. This object is achieved by the invention.

The invention relates to aqueous emulsions of (A) organopolysiloxane with aliphatic radicals bonded via oxygen to silicon with a molecular weight of at least 620 g / mol, which, as emulsifier (B), salt of water-soluble organic or inorganic acid and polysiloxane, in addition to other siloxane units Contains siloxane units which contain monovalent, SiC-bonded radicals with basic nitrogen in amounts of at least 0.5% by weight of basic nitrogen, based on the weight of this polysiloxane, contain, characterized in that they are free of water-soluble solvents or octanols or contain such solvents or octanols in amounts of at most 5 percent by weight, based on the weight of the emulsifier (B) defined above.

The organopolysiloxanes (A) with aliphatic radicals bonded to silicon via oxygen and having a molecular weight of at least 620 g / mol can be any organopolysiloxanes with aliphatic radicals bonded to silicon via oxygen and having a molecular weight of at least 620 g / mol, which are also previously described in Water could be emulsified. These are preferably those of the formula<chemistry id="chem0001" num="0001"><img file="EP0242798A2_D0001.tif" /></chemistry>where R is the same or different SiC-bonded, monovalent organic radicals, R² the same or different monovalent aliphatic radicals, x denotes 0, 1, 2 or 3, on average 0.75 to 1.5, preferably 0.9 to 1.1 and y 0, 1, 2 or 3, on average 0.2 to 2.0, preferably 0.4 to 1.2, of course with the proviso that these organopolysiloxanes have a molecular weight of at least 620 g / mol.

The organic radicals R preferably contain¹ at most 14 carbon atoms per residue. Examples of organic radicals R are straight-chain or branched alkyl radicals, such as the methyl, ethyl, n-propyl, isopropyl, n-butyl and sec-butyl radical, as well as octyl and tetradecyl radicals; Cycloalkyl radicals, such as the cyclohexyl radical and methylcyclohexyl radicals; Hydrocarbon radicals with aliphatic carbon-carbon double bonds, such as the vinyl and allyl radicals; Aryl groups such as the phenyl group and xenyl groups; Alkaryl radicals, such as tolyl and xylyl radicals; and aralkyl groups such as the benzyl group.

The SiC-bonded organic radicals R can also be substituted, monovalent hydrocarbon radicals with preferably at most 14 carbon atoms per radical. Examples of such substituted hydrocarbon radicals are, in particular, halogenated hydrocarbon radicals, such as the 3,3,3-trifluoropropyl radical and o-, m- and p-_C.hlorophenyl radicals, and SiC-bonded radicals composed of carbon, hydrogen, fluorine and ether oxygen atoms as single atoms, such as the 1,1,2,2-tetrafluoroethoxypropyl and the 1,1,2,2,3,3-hexafluoropropyloxypropyl radical .

Because of the easier accessibility, at least 50% of the number of SiC-bonded organic residues in the organopolysiloxane (A) and thus the residues R are preferably¹ Methyl ester. The other organic radicals which may be present in the organopolysiloxane (A) are preferably vinyl or phenyl radicals or mixtures of such radicals.

The radicals R preferably contain² at most 4 carbon atoms per radical and are alkyl radicals, such as the methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and tert-butyl radical, the ethyl radical being particularly preferred.

The organopolysiloxanes (A) and thus also the organopolysiloxanes of the formula given above preferably have a viscosity of 15 to 2000 mPa.s at 25 ° C., in particular 20 to 200 mPa.s at 25 ° C.

Organopolysiloxane (A) can be a single type of organopolysiloxane. However, it can also be a mixture of at least two different types of such organopolysiloxanes.

The preparation of organopolysiloxanes suitable as organopolysiloxane (A) is known and is described, for example, in GB-A-685 173 (published December 31, 1951, Dow Corning Limited), US-A-28 42 521, issued July 8, 1958, S. Nietzsche et al., Wacker-Chemie GmbH, FR-A-14 75 709, issued April 7, 1967, General Electric Company, US-A-36 68 180, issued June 6, 1972, JL Brennan et al., Stauffer-Wacker -Silicone Corporation, US-A-37 92 071, issued February 12, 1974, p. Nietzsche et al., Wacker-Chemie GmbH, US-A-38 46 358, issued November 5, 1974, GF Roedel, General Electric Company, US-A-42 09 454, W. Graf et al., Wacker-Chemie GmbH and US-A 42 98 753, issued November 3, 1981, A. Schinabeck et al., Wacker-Chemie GmbH.

Particularly preferred as organopolysiloxanes (A) are those which can be obtained by reacting methyltrichlorosilane with ethanol and water.

The emulsions according to the invention preferably contain organopolysiloxane (A) in amounts of 1 to 60 percent by weight, in particular 20 to 50 percent by weight, in each case based on the total weight of the respective emulsion.

The polysiloxanes by their reaction with water-soluble organic or inorganic acid, the emulsifier (B) in the aqueous emulsions of organopolysiloxane according to the invention are preferably those of units of the formula<chemistry id="chem0002" num="0002"><img file="EP0242798A2_D0002.tif" /></chemistry>where R¹has the meaning given above for it, R 3 denotes the monovalent, SiC-bonded radicals with basic nitrogen, which can likewise be the same or different, R⁴ Is hydrogen or has the same meaning as R²has, m 0, 1, 2 or 3, on average 0 to 2, preferably 0 to 1.8, n 0 or 1, on average 0.1 to 0.6, preferably 0.15 to 0.30, z 0, 1 , 2 or 3, on average 0.01 to 0.8, preferably 0.1 to 0.6 and the sum of the respective average values ​​of m + n + z is at most 3.4.

All statements about the residues R in organopolysiloxane (A) and all individual examples of residues R¹that were given in connection with organopolysiloxane (A) also apply to the radicals R¹ in the emulsifier (B) with the proviso that in the emulsifier (B) the residue R¹ the phenyl radical is also very preferred.

As monovalent SiC-bonded residues with basic nitrogen, i.e. as residues R³ are those of the formula<chemistry id="chem0003" num="0003"><img file="EP0242798A2_D0003.tif" /></chemistry>where R⁵ Hydrogen or identical or different alkyl or aminoalkyl radicals and R⁶ means a divalent hydrocarbon residue.

The examples of alkyl radicals R, which likewise preferably have at most 14 carbon atoms per radical, also apply in full to the alkyl radicals R.⁵. Preferably, however, is on each nitrogen atom in the residues of the formula<chemistry id="chem0004" num="0004"><img file="EP0242798A2_D0004.tif" /></chemistry>bound at least one hydrogen atom.

Examples of divalent hydrocarbon radicals R⁶ are the methylene and ethylene radical as well as propylene, butylene, cyclohexylene, octadecylene, phenylene and butenylene radicals. Especially because of the easier accessibility than the rest_R⁶ the n-propylene radical is preferred.

The rest of the formula is particularly preferred as a monovalent, SiC-bonded radical with basic nitrogen<chemistry id="chem0005" num="0005"><img file="EP0242798A2_D0005.tif" /></chemistry>

Further examples of SiC-bonded radicals R³ with basic nitrogen are those of the formulas<chemistry id="chem0006" num="0006"><img file="EP0242798A2_D0006.tif" /></chemistry><chemistry id="chem0007" num="0007"><img file="EP0242798A2_D0007.tif" /></chemistry><chemistry id="chem0008" num="0008"><img file="EP0242798A2_D0008.tif" /></chemistry><chemistry id="chem0009" num="0009"><img file="EP0242798A2_D0009.tif" /></chemistry><chemistry id="chem0010" num="0010"><img file="EP0242798A2_D0010.tif" /></chemistry>and<chemistry id="chem0011" num="0011"><img file="EP0242798A2_D0011.tif" /></chemistry>

All remarks about the residues R² in organopolysiloxane (A) and all individual examples of hydrocarbon residues R^e.g.that have been specified in connection with organopolysiloxane (A) also apply in their entirety to aliphatic radicals R² in the emulsifier (B).

The polysiloxanes which, in addition to other siloxane units, contain those siloxane units which have monovalent, SiC-bonded radicals with basic nitrogen, for example by equilibration or condensation of, for example, gamma-aminoethylaminopropyltrimethoxysilane or gamma-aminoethylaminopropylmethyldimethoxysilane or a mixture of such silanes organic polysiloxanes that are free of basic nitrogen. The polysiloxanes used here preferably have a molecular weight of at least 350 g / mol. These polysiloxanes can be, for example:

Monoorganopolysiloxanes, such as monoalkyl or monoarylpolysiloxanes, for example those of the empirical formula<chemistry id="chem0012" num="0012"><img file="EP0242798A2_D0012.tif" /></chemistry>or<chemistry id="chem0013" num="0013"><img file="EP0242798A2_D0013.tif" /></chemistry>Hydrolyzates of isooctyltrichlorosilane, mixed hydrolyzates of phenyltrichlorosilane and n-propyltrichlorosilane, methoxy groups-containing copolymers of monomethylsiloxane and monoisooctylsiloxane units, dimethylpolysiloxanes end-bonded by trimethylsiloxy groups, such as hydroxyl units in the terminal units of methyl units, such as Si-terminated units<chemistry id="chem0014" num="0014"><img file="EP0242798A2_D0014.tif" /></chemistry>having dimethylpolysiloxanes, where R² has the meaning given above for this, polyethyl silicates and copolymers of dimethyl siloxane and monomethyl siloxane units.

The water-soluble organic or inorganic acids which are used to prepare the emulsifier (B) in the aqueous organopolysiloxane emulsions according to the invention can be the same as those which have hitherto been used for the preparation of salts of water-soluble organic or inorganic acid and polysiloxane with basic nitrogen SiC-bound residues could be used. Examples of such acids are hydrochloric acid, sulfuric acid, acetic acid, propionic acid and diethyl hydrogen phosphate. Acetic acid and propionic acid are preferred.

Compounds which can be present as emulsifiers (B) in the emulsions according to the invention are already known. For this purpose, in addition to EP-A-0068671 already mentioned at the beginning, for example US-A-3 890 269, issued June 17, 1975, ER Martin, Stauffer Chemical Company, US-A-3 355 424, L. Brown, Dow Corning Corporation and US-A-4,247,330, issued January 27, 1981 to AJ Sanders, Jr., SWS Silicones Corporation.

The term "basic nitrogen", as used here in the description and at least one of the claims in connection with quantities, refers to nitrogen, calculated as an element.

The emulsions according to the invention preferably contain salt (B) of water-soluble organic or inorganic acid and polysiloxane which, in addition to other siloxane units, contains those siloxane units which contain monovalent, SiC-bonded radicals with basic nitrogen in amounts of at least 0.5 percent by weight of basic nitrogen have the weight of this polysiloxane, in amounts of 1 to 30 percent by weight, in particular 5 to 20 percent by weight, in each case based on the total weight of the respective emulsion, and from 18 to 50 percent by weight, in particular from 30 to 50 percent by weight, based on the weight of organopolysiloxane (A).

The aqueous emulsions according to the invention are preferably prepared by first mixing organopolysiloxane (A) with emulsifier (B) and then emulsifying the mixture thus obtained in water. Both the mixing and the emulsification mentioned above can be carried out in conventional mixing devices suitable for the production of emulsions, such as high-speed stator-rotor stirring devices according to Prof. P. Willems as they are known under the registered trademark "Ultra-Turrax", pressure emulsifying machines or colloid mills.

The emulsions according to the invention are preferably also free from organic solvents other than water-soluble solvents or octanols or contain such solvents in amounts of at most 5 percent by weight, based on the weight of emulsifier (B).

The aqueous emulsions of organopolysiloxane according to the invention are suitable, for example, for hydrophobicizing mineral substances, such as building materials, for example Roof tiles bricks, reinforced or unreinforced concrete, natural stones, including limestone, gypsum, cinder blocks, sand-lime bricks and asbestos by applying the emulsions to these building materials after their shaping and, if necessary, further treatment, such as after firing the bricks, this application before or after the application of the Building materials to their final destination, such as a facade or a street.

The aqueous emulsions of organopolysiloxane according to the invention are also suitable as hydrophobizing additives for inorganic binders, for example gypsum, mortar or plaster, concrete, including gas concrete, or sand-lime brick before they are shaped, in particular in a mixture with the mixing water.

The aqueous emulsions of organopolysiloxane according to the invention are also suitable as binders for inorganic fibrous substances, such as glass fibers, asbestos, rock and slag wool.

The aqueous emulsions of organopolysiloxane according to the invention are furthermore suitable as additives for dispersions of purely organic resins, such as polyvinyl acetate or polyacrylic acid dispersions, and as water repellents in phenolic resin-bonded mineral thermal insulation materials.

The aqueous emulsions of organopolysiloxane according to the invention are also suitable as additives to inorganic paints, such as water glass and lime paints.

The aqueous emulsions of organopolysiloxane according to the invention are also suitable as binders in aqueous paints on, for example, wood, masonry, metals, plastics or glass, it being possible for these aqueous paints to contain any pigments, including aluminum powder.

Finally, the aqueous emulsions according to the invention are also suitable, for example, as primers for organopolysiloxane elastomers.

At the latest when they are finally used, condensation catalysts or agents for improving the adhesion of the coatings produced from these emulsions to the substrates on which they were produced can be added to the emulsions according to the invention.

In the following examples, all parts and percentages are by weight, unless stated otherwise.

a) The monomethylsiloxane used in the following examples as organopolysiloxane (A) with ethyl groups bonded to silicon via oxygen was prepared as follows: A mixture of 10 mol of ethanol and 5.5 mol of water was added from a dropping funnel to a mixture of 6 mol of methyltrichlorosilane and 400 g of toluene were added dropwise with stirring, gaseous hydrogen chloride escaping and the contents of the reaction vessel, which were initially at 30 ° C., cooled down considerably. After the addition of the ethanol-water mixture had ended, the reaction mixture was warmed to 40 ° C. and a mixture of ethanol, water and hydrogen chloride was distilled off at 20 hPa (abs.). Residual hydrogen chloride was neutralized with anhydrous sodium carbonate and then residual ethanol and water at 30 hPa (abs.) Distilled up to 120 ° C as the temperature of the liquid flask contents. After cooling and filtering the residue obtained in the distillation, a clear, colorless liquid with a viscosity of 20 mPa.s at 23 ° C. was obtained. It has the gross formula<chemistry id="chem0015" num="0015"><img file="EP0242798A2_D0015.tif" /></chemistry>

This organopolysiloxane has a molecular weight of 650 g / mol.

b) The salt of water-soluble organic acid and organopolysiloxane with SiC-bonded radicals with basic nitrogen used as emulsifier (B) in the following examples was prepared as follows:

In a 11-necked three-necked flask equipped with a stirrer, dropping funnel and reflux condenser, 150 g of N- (2- Aminoethyl-3-aminopropyltrimethoxysilane, which is also referred to as gamma-aminoethylaminopropyltrimethoxysilane. The mixture thus obtained was heated to boiling under reflux for 6 hours, then cooled to 30 ° C., mixed with 2.5 ml of 10% aqueous hydrochloric acid, freed from volatile constituents by heating to 140 ° C. and filtered. The organopolysiloxane thus obtained contains 2.9% basic nitrogen, based on its weight. To prepare the salt, 8 parts of this organopolysiloxane were mixed with 1 part of glacial acetic acid.

example 1

At room temperature, 7 parts of the organopolysiloxane, the production of which was described above under a), are mixed with 3 parts of the organopolysiloxane salt, the production of which was described under b) above, in a high-speed stator-rotor stirrer according to Prof. P. Willems. The mixture thus obtained is slowly mixed in the same stirrer with water until a creamy mass is formed and then with further water to form an O / W emulsion, a total of 10 parts of water being used. Their characteristics are:<tables id="tabl0001" num="0001"><img file="EP0242798A2_D0016.tif" /></tables>

After production, after 7 days and after 1 year, it dries on glass at room temperature to a clear, hard film.

Example 2

1 Part of the emulsion, the preparation of which was described in Example 1, is diluted with 15 parts of water. The mixture thus obtained was used as mixing water for a commercially available plaster. After 2 hours storage of a test specimen made from this plaster or plaster at room temperature under water, this body only absorbed 2% water, based on its weight, while with the same water storage a test specimen made of plaster, in which water was used as mixing water without additives , 14% water, based on its weight.

Example 3

7 Parts of the emulsion, the preparation of which was described in Example 1, are mixed with 50 parts of a commercially available aqueous lime paint. After a coat of this lime paint has dried, a drop of water on this coat evaporates before it has penetrated the coat.

Example 4

1 Part of the emulsion, the preparation of which was described in Example 1, is diluted with 5 parts of water. In an electrophoresis trough which is conventional for electrocoating, an iron sheet is coated on the cathode at a voltage of 60 V within 2 minutes with a film of about 100 micrometers from this diluted emulsion. This film exhibits excellent water repellency after heating to 150 ° C for one hour.

Example 5

1 Part of the emulsion, the preparation of which was described in Example 1, is diluted with 5 parts of water and sprayed onto 5 parts of rock wool at a rate of 1500 liters per hour. The rock wool treated in this way is pressed after drying for 10 minutes at 200 ° C. These compacts show no noticeable discolouration compared to untreated rock wool. Test specimens of such pellets measuring 10 cm × 10 cm × 4 cm are held in water 2 cm below the water surface for 30 minutes, then placed on a grating with the narrow edge and left to drain for 5 minutes. The following water absorption values ​​are then determined:

<tables id="tabl0002" num="0002"><img file="EP0242798A2_D0017.tif" /></tables>