JPH0681788B2 - Impregnation of cement-bonded cellulose fibre building components. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous emulsion of an alkoxy-containing, nitrogen-free organopolysiloxane and an alkyltrialkoxysilane.

Aqueous emulsions of alkyltrialkoxysilanes and basic nitrogen-containing organopolysiloxanes with alkoxy groups are known from U.S. Pat. No. 4,661,551 (April 28, 1987, H. Mayer et al., published by Wacker-Chemie GmbH). These emulsions are suitable for hydrophobing building materials, including concrete and cement-bonded fiber building components. However, the treated building materials yellow under the influence of light and air.

Aqueous emulsions of alkyltrialkoxysilanes for the hydrophobization of building materials are in particular described in U.S. Pat. No. 5,629,499.
No. 4877654 (October 31, 1989, ME Wilson (W
ilson, published by PCR Inc. However, alkyltrialkoxysilanes are relatively expensive.
The use of cost-effective emulsions of alkoxy-containing organopolysiloxanes for hydrophobizing building materials is described in U.S. Pat. No. 4,704,416 (1988).
(H. Eck and M. Roth, Wacker-Chemie GmbH, May 3, 1986) However, the hydrophobing effect of such organopolysiloxanes is unsatisfactory.

When the emulsions are used to impregnate the surfaces of building materials, the methyltriethoxysilane, which penetrates deep into the building material, and the polymethylsiloxane, which mainly adheres to the surface and causes an undesirable gloss there, are separated out.

The object of the present invention is to produce an economical aqueous emulsion for the water-repellent impregnation of building materials, in particular cement-bonded fiber building elements, which exhibits good impregnation action without yellowing under the influence of light and air and without causing gloss on the surface of the building material.

This object is achieved according to the invention by the preparation of an aqueous emulsion of a basic, nitrogen-free organopolysiloxane (A) and an alkyltrialkoxysilane (B), which emulsion contains an emulsifier (C) and water (D), wherein the organopolysiloxane (A) is an alkyltrialkoxysilane of the formula: wherein R represents the same or different monovalent, optionally substituted C ₁ -C ₁₈ -hydrocarbon radicals, R ¹ represents the same or different monovalent C ₁ -C ₆ -hydrocarbon radicals, a is 0, 1, 2, or
or 3 and averaging 0.75 to 1.5, and b is 1, 2, or 3 and averaging 0.2 to 2.0; and
It has a molecular weight of

Although not shown in the formula, some of the radicals R may be replaced by hydrogen atoms directly bonded to silicon atoms, however this is not preferred.

The radicals R in particular contain at most 12 carbon atoms per radical.
Examples of groups R are alkyl groups, such as methyl-, ethyl-,
n-Propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, iso
Pentyl, neopentyl, t-pentyl, hexyl, e.g. n-hexyl, heptyl, e.g.
n-heptyl, octyl, for example n-octyl and iso-octyl, for example 2,2,4-trimethylpentyl, nonyl, for example n-nonyl, decyl, for example n-decyl, dodecyl, for example n-dodecyl;
alkenyl groups, such as vinyl and allyl; cycloalkyl groups, such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl; aryl groups, such as phenyl and naphthyl; alkaryl groups, such as o-, m-, p-tolyl, xylyl and ethylphenyl; aralkyl groups, such as benzyl, α- and β-phenylethyl.

Examples of substituted groups R are cyanoalkyl groups, e.g. β-
cyanoethyl groups, and halogenated hydrocarbon groups, such as halogen alkyl groups, for example, 3,3,3-trifluoro-n-
Propyl, 2,2,2,2',2',2'-hexafluoroisopropyl, heptafluoroisopropyl, and halogenaryl groups such as o-, m-, and p-chlorophenyl.

Because they are relatively readily available, in particular at least
50%, in particular at least 80%, of the radicals R are methyl radicals.

In the above formula, a is in particular on average 0.9 to 1.1, and b is in particular 0.8 to 1.4, especially 1.0 to 1.2.

It is possible to use one organopolysiloxane, especially one of the above formula, or it is also possible to use several organopolysiloxanes.

Particularly preferred organopolysiloxanes (A) are those obtainable in water by reacting methyltrichlorosilane or phenyltrichlorosilane with ethanol, _{e.g. ,} those having the empirical formula _CH3Si ( _OC2H5 ) _{0.8O1.1 or C6H5Si ( OC2H5 ) 0.72O1.14} .

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

Alkyltrialkoxysilanes (B) contain the same or different monovalent optionally substituted _C2 - _C15 -alkyl groups and in particular the same or different optionally substituted _C1 - _C6 -alkoxy groups.

Preferred alkyl groups have 4 to 10 carbon atoms, for example n-butyl, s-butyl, isobutyl, t-butyl.
Butyl, n-pentyl, iso-pentyl, neo-
Pentyl, t-pentyl, hexyl, e.g., n-
hexyl, heptyl, for example n-heptyl, octyl, for example n-octyl and iso-octyl, for example 2,2,4-trimethylpentyl, nonyl,
For example, an n-nonyl group, a decyl group, for example an n-decyl group;
Cycloalkyl groups are, for example, cyclopentyl, cyclohexyl and cycloheptyl groups and methylcycloalkyl groups.

The substituted alkyl group may be a cyanoalkyl group, e.g., β
- cyanoethyl groups and halogen alkyl groups, for example 3,3,
3-trifluoro-n-propyl group, 2,2,2,2',2',2'
- hexafluoroisopropyl and heptafluoroisopropyl groups.

Preferred alkoxy groups of the alkyltrialkoxysilanes have 1 to 4 carbon atoms, for example methoxy, ethoxy, n-propoxy, isopropoxy, n-
butoxy, isobutoxy, sec-butoxy and tert-butoxy groups, with methoxy and ethoxy groups being particularly preferred.

The alkoxy groups of the alkyltrialkoxysilane may be substituted with cyano groups and halogen atoms. One type of alkyltrialkoxysilane or a mixture of several types of alkyltrialkoxysilanes may be used.

The aqueous emulsions according to the invention contain emulsifiers known per se.

As anionic emulsifiers, the following are particularly suitable: 1. alkyl sulfates, in particular those with a chain length of 8 to 18 C atoms, alkyl- and alkaryl ether sulfates having 8 to 18 C atoms and 1 to 40 ethylene oxide (EO) or propylene oxide (PO) units in the hydrophobic group, 2. sulfonates, in particular alkyl sulfonates having 8 to 18 C atoms, alkylaryl sulfonates having 8 to 18 C atoms, taurides, esters and semiesters of sulfosuccinic acid with monohydric alcohols or alkylphenols having 4 to 15 C atoms; optionally these alcohols or alkylphenols may be EO or PO units.
- 1 to 40 units may be ethoxylated.

3. alkali metal and ammonium salts of carboxylic acids having 8 to 20 carbon atoms in the alkyl-, aryl-, alkaryl- or aralkyl group, 4. phosphoric acid partial esters and their alkali metal and ammonium salts, in particular alkyl- and alkaryl phosphates having 8 to 20 carbon atoms in the organic radical, alkyl-
or 8 to 20 C atoms and EO in the alkaryl group
Alkyl ether or alkaryl ether phosphates containing 1 to 40 units.

As non-ionic emulsifiers, the following are particularly suitable: 5. Polyvinyl alcohols with a degree of polymerization of 500 to 3000, which additionally contain 5 to 50% vinyl acetate units and 8 to 20% in the species; 6. Alkyl polyglycol ethers, in particular those containing 8 to 10% EO units.
40 and those with alkyl groups of 8 to 20 C atoms, 7. Alkylaryl polyglycol ethers, especially EO-
those with 8 to 40 units and 8 to 20 C atoms in the alkyl and aryl groups, 8. ethylene oxide/propylene oxide (EO/PO)-
Block copolymers, especially those containing 8 to 40 EO or PO units
9. Fatty acids having 6 to 24 C atoms, 10. Natural substances and their derivatives, such as lecithin, lanolin, saponin, cellulose; cellulose alkyl ethers and carboxyalkylcelluloses, whose alkyl groups each have up to 4 carbon atoms, 11. Linear organo(poly)siloxanes containing polar groups, in particular those having alkoxy groups with up to 24 C atoms and/or up to 40 EO- and/or PO- groups.

The following are particularly suitable as cationic emulsifiers: 12. Salts of primary, secondary and tertiary fatty amines having 8 to 24 C atoms with acetic acid, sulfuric acid, hydrochloric acid and phosphoric acid, 13. Quaternary alkyl- and alkylbenzolammonium salts, especially those whose alkyl groups have 6 to 24 C atoms, in particular the halides, sulfates, phosphates and acetates, 14. Alkylpyridinium, alkylimidazolinium and alkyloxazolinium salts, especially those whose alkyl chains have up to 18 C atoms, in particular the halides, sulfates, phosphates and acetates.

As amphoteric emulsifiers, the following are suitable: 15. Long-chain substituted amino acids, such as N-alkyl-
Di-(aminoethyl-)glycine or N-alkyl-2
-aminopropionates, 16. betaines, e.g. N- with _C8 - _C18 acyl groups
(3-acylamidopropyl)-N:N-dimethylammonium salts and alkyl-imidazolium-betaines.

As the emulsifier, a nonionic emulsifier, in particular the polyvinyl alcohol mentioned above under 5., is preferred. Particularly preferred polyvinyl alcohols further contain 10 to 15 vinyl acetate units.
% and has a degree of polymerization of 1200-2000.

The aqueous emulsions according to the invention contain from 30 to 95% by weight, in particular from 35 to 70% by weight, especially from 45 to 60% by weight, of water.

In the emulsions according to the invention, the weight ratio of organopolysiloxane (A) to alkyltrialkoxysilane (B) is from 100:1 to 1:1. In particular, the weight ratio of organopolysiloxane (A) to alkyltrialkoxysilane (B) is from 24:1 to 1:1. In particular, the weight ratio of 10:1 to 2:1, in particular
A weight ratio of organopolysiloxane (A) to alkyltrialkoxysilane (B) of 5:1 to 3:1 is particularly advantageous.

The emulsifier (C) is an organopolysiloxane (A).
and 0.1 of the total amount of alkyltrialkoxysilane (B).
It may be from 2 to 15% by weight. It is especially from 2 to 10% by weight.

The emulsions according to the invention may additionally contain customary fillers and thickeners, in particular reinforcing fillers, i.e., BEs of more than 50 m ² /g.
It can contain fillers with T-surface area, such as pyrogenically produced silicic acid, precipitated silicic acid and silicon-aluminum mixed oxide with large BET-surface area.Highly dispersed silicic acid is particularly suitable.It can also use one filler or a mixture of at least two fillers.

The emulsions according to the invention furthermore contain alkyltrialkoxysilanes in the range of 4 to 100% by weight, which are then very hydrolytically stable.
It may also contain buffer substances that stabilize the pH value in the range of 7. All organic and inorganic acids and bases that are chemically inert to the other components of the emulsion according to the invention are suitable, especially alkali metal, alkaline earth metal and ammonium salts of carboxylic, phosphoric, carbonate and sulfate. Sodium carbonate, sodium bicarbonate, sodium hydrogen phosphate, sodium acetate and mixtures of acetic acid and aqueous ammonia are particularly suitable. The preferred amount of buffer substance is 0.01 to 4% by weight.

The emulsion according to the invention may further comprise, in addition to the above components:
The additives may include antifungal agents, antibacterial agents, antialgae agents, antimicrobial agents, fragrances, corrosion inhibitors, antifoaming agents, and, although not preferred, organic solvents. The emulsions according to the invention contain the additives in an amount of 0.001 to 1% by weight, preferably 0.01 to 0.1% by weight, of each additive.

The quantities of the filler, thickener, buffer substance and additive are expressed as organopolysiloxane (A), alkyltrialkoxysilane (B), emulsifier (C) and water (D), respectively.
is related to the total weight of

The present invention also provides a process for preparing an aqueous emulsion of a basic nitrogen-free organopolysiloxane (A) and an alkyltrialkoxysilane (B), which emulsion comprises an emulsifier (C) and water (D), wherein the organopolysiloxane (A) is an alkyltrialkoxysilane of the formula: wherein R represents the same or different monovalent, optionally substituted C ₁ -C ₁₈ -hydrocarbon radicals, R ¹ represents the same or different monovalent C ₁ -C ₆ -hydrocarbon radicals, a is 0, 1, 2 or 3 and is on the average 0.75 to 1.5, and b is 1, 2 or 3;
and the average is 0.2 to 2.0] and at least 600
(having a molecular weight of 10 ...
The organopolysiloxane (A), the alkyltrialkoxysilane (B) and the emulsifier (C) are emulsified together, and then the remaining water is added and emulsified.

The aqueous emulsion of the present invention can be produced by a conventional method for producing aqueous emulsions. In particular, first, only a portion of the water is emulsified with the organopolysiloxane (A), the alkyltrialkoxysilane (B), and the emulsifier (C) until a viscous oil phase is formed, and then the remaining water is added and emulsified to form a less viscous emulsion. The organopolysiloxane can also be dissolved in the alkyltrialkoxysilane, and both components are added simultaneously to the emulsion consisting of the emulsifier and water.

The emulsification can be carried out batchwise in an emulsifying apparatus or, in particular, continuously in a through-mixing apparatus.

The emulsion is preferably heated at 0 to 50°C, more preferably at 20°C, and more preferably at
It is produced at a pressure of 0.5 to 2 MPa (absolute), especially 0.1 MPa (absolute).

The emulsions according to the invention are suitable for use in building materials, e.g.
It is also suitable for the water-repellent impregnation of synthetic stone, concrete, cement, walls and porous concrete (Porenbeton).

This emulsion is particularly suitable for the water-repellent impregnation of cement-bonded fiber building components, whose fibers are made of natural or synthetic fibers.Suitable natural fibers are mineral fibers, such as stone wool, quartz or ceramic fibers, or plant fibers, such as cellulose.Suitable synthetic fibers are, for example, glass fibers, plastic fibers, and carbon fibers.

The use of the emulsions according to the invention for the impregnation of cement-bonded cellulose fiber building materials is particularly advantageous. The cellulose fibers may be, for example, jute, coconut or hemp fibers or may originate from paper, cardboard or waste paper.

The emulsions according to the invention are suitable for use in mass, ie the emulsions are added to hydraulic mixtures for the production of building materials before setting, or for the impregnation of building elements after setting.

The emulsion of the present invention can be diluted with water before its use as hydrophobizing and impregnating agent.When impregnating the surface of building materials after solidification, it is preferable to dilute the total amount of organopolysiloxane (A) and alkyltrialkoxysilane (B) up to 1% by weight.

In the following examples, unless otherwise stated: a) all amounts are by weight; b) all pressures are 0.1 MPa (absolute); c) all temperatures are 20°C.

EXAMPLES Preparation of Organopolysiloxane (A): The monomethylsiloxane containing ethyl groups bonded to the silicon atom via an oxygen atom, used as organopolysiloxane (A) in the following examples, was prepared as follows: A mixture of 10 moles of ethanol and 5.5 moles of water was added dropwise from a dropping funnel to a mixture of 6 moles of methyltrichlorosilane and 400 g of toluene, with stirring, while allowing gaseous hydrogen chloride to escape, and the contents of the reaction vessel, which were initially at 30° C., were vigorously cooled. After the addition of the ethanol-water mixture was complete, the reaction mixture was heated to 40° C., and ethanol, water, and hydrogen chloride were distilled off from the mixture at 0.20 kPa (absolute). The remaining hydrogen chloride was neutralized with anhydrous sodium carbonate, followed by the remaining ethanol and water at 0.30 kPa (absolute).
a (absolute) until the temperature of the liquid flask contents reached 120°C. After cooling and filtering the residue obtained during distillation, a clear, colorless liquid was obtained with a viscosity of 20 mPa.s at 23° _C . It has the empirical formula: _CH3Si ( _OC2H5 ) _{0.8O1.1 .}

The organopolysiloxane has a molecular weight of 650.

Example: Preparation of an emulsion according to the present invention: In a Turrax emulsifier, 20.25 parts by weight of water
having a degree of polymerization of about 1600 and further comprising acetoxyethyl units
Polyvinyl alcohol (Wacker-Hill) with 11-14%
Polybio of Wacker-Chemie, Munich
Polyviol ) W25/140) 2.25 parts by weight, together with 1000U/
The organopolysiloxane was emulsified in 1 minute.
Polysiloxane (A) 38 parts by weight, isooctyltrimethicone
Xysilane (Wacker-Chemie GmbH, Munich,
VP1316) 10 parts by weight and BET-surface area 120 m²/g
Diffused silica (Wacker-Chemie GmbH, Munich)
Wacker HDK H15 ) 2 parts by weight in the above order
The mixture was emulsified at 15,000 U/min. A viscous oil phase was produced.
Further emulsification with 27.5 parts by weight of water resulted in a more diluted emulsion.
The total time for emulsification was 10 minutes.
Finally, 20% by weight of vinegar was added to the resulting emulsion.
Add 0.1 parts by weight of sodium phosphate solution and 0.05 parts by weight of antibacterial agent.
The mixture was stirred.

Preparation of an emulsion not according to the invention: An emulsion was prepared in the same manner, but using 10 parts by weight of organopolysiloxane (A) instead of 10 parts by weight of isooctyltrimethoxysilane. This emulsion contained 48 parts by weight of organopolysiloxane (A).

Use example: Preparation of cement-bonded fiber building components as test specimens: 10 parts by weight of paper fabric (Papierhygiene GmbH, Heidelberg) are crushed in a crusher and washed with water.
After storing the wet paper blocks for 24 hours,
After homogenization in a dissolver, 5 parts by weight of fine quartz sand, 75 parts by weight of Portland cement 45F, 10 parts by weight of calcium carbonate, and optionally a hydrophobizing agent were added and mixed again intensively. The fiber-cement mass was then squeezed through a steel sieve with a piston in a water-vacuum nozzle. The moist pressed mass, 9.5 cm in diameter and 1.5 cm thick, was stored for 6 days at a relative atmospheric humidity of 50% to solidify.

The amount of hydrophobizing agent added was calculated as a weight percent of the total amount of cement fiber, sand, and calcium carbonate. 0.1 or 5 weight percent of the hydrophobizing agent was added.

The following hydrophobizing agents were used: 1. the emulsion according to the invention, containing 38% by weight of organopolysiloxane and 10% by weight of alkyltrialkoxysilane; 2. the emulsion not according to the invention, containing 48% by weight of organopolysiloxane; 3. no hydrophobizing agent. After the storage time had elapsed, some specimens prepared without hydrophobizing agent were immersed in the impregnation solution for 5 minutes and then stored for 5 days. The impregnation solution used was the hydrophobizing agent diluted with water in a ratio of 1:8 or 1:15. The surfaces of the specimens retained their matte appearance.

Pressurized water test according to DIN 18180: The test specimens were stored at room temperature in a water bath for 60 or 120 minutes.
The water column above the specimen surface was 50 mm. The water absorption was determined gravimetrically and calculated as a percentage by weight.

The results of the pressurized water test by adding a hydrophobizing agent to the mass are shown in Table 1.

The results of the pressurized water test after impregnation by immersion in diluted emulsion as hydrophobizing agent are shown in Table II.

Claims (1)

[Claims] 1. A method for impregnating a cement-bonded cellulose fiber building component with an aqueous emulsion of a basic nitrogen-free organopolysiloxane (A) and an alkyltrialkoxysilane (B), which emulsion contains an emulsifier (C) and water (D), wherein the organopolysiloxane (A) is an alkyltrialkoxysilane having the formula: wherein R represents the same or different monovalent, optionally substituted C ₁ -C ₁₈ -hydrocarbon radicals, R ¹ represents the same or different monovalent C ₁ -C ₆ -hydrocarbon radicals, a is 0, 1, 2, or
or 3 and averaging 0.75-1.5, and b is 1, 2 or 3 and averaging 0.2-2.0; and having a molecular weight of at least 600.