CA1277891C

CA1277891C - Aqueous systems containing silanes for rendering masonry surfaces water repellant

Info

Publication number: CA1277891C
Application number: CA000525997A
Authority: CA
Inventors: Ralph J. Depasquale; Michael E. Wilson
Original assignee: PCR Inc
Current assignee: Construction Research and Technology GmbH
Priority date: 1986-02-14
Filing date: 1986-12-22
Publication date: 1990-12-18
Anticipated expiration: 2007-12-18
Also published as: DE3688837T3; US4648904B1; JPH05170574A; DE3688837T2; EP0234024B1; JPS62197369A; ATE92452T1; EP0234024B2; AU594426B2; AU6865787A; DE3688837D1; EP0234024A1; US4648904A; ES2042492T3; ES2042492T5; JPH0313195B2

Abstract

ABSTRACT OF THE DISCLOSURE
There is provided an aqueous emulsion of (a) a hydrolyzable silane having the general formula:

Rn - Si - (R')4-n wherein R is a hydrocarbyl group containing from 1 to 20 carbon atoms, R' is a hydrolyzable group and n is 1 or 2, and oligomers thereof, e.g., dimers and trimers, and other oligomers, (b) an emulsifying agent having an HLB value of from 4 to 15, and (c) water. The emulsion is useful for rendering porous ceramic materials water repellant.

Description

~z77as~

Docket No.: 40,127 This invention relates to water based systems which are especially useful in rendering porous masonry surfaces water repellant. .~ore particularly, the present invention relates to aqueous emulsions of hydrolyzable silanes, and/or oligomers thereof, useful in treating masonry surfaces to render such surfaces water repellant.

m e utility of alkoxysilanes as masonry water repellants (~WR) is widely known. Compositions currently in use employ solutions of silanes in various solvents such as alcohol (U. S. Patent 3,772,065 dated 13 November 1973 and U. S. Patent 4,342,796 dated 3 August 1982) or hydrocarbons (Patent 4,525,213 dated 25 June 1985). Principal limitations of the solvent type compositions include the toxicity and flammability of the solvents employed. In the case of the low molecular weight alcohols, e.g., isopropanol, the rapid evaporation rate limits the extent of penetration and curing of the silane in the substrate. Reference may also be had to U. S. Patent 2,683,674 dated 13 July 1954 showing the use of alkyl polysiloxanes in a volatile solvent solution~
Aqueous solutions of hydrolyzed silanes have been reported as effective masonry water repellant compositions. (See U. S. Patent 4,517,375 dated 14 May 1985).
Aqueous emulsions of organopolysiloxane oils (See U. S.
Patent 4,476,282 dated 9 October 1984) and an aqueous dispersion of silicone resins (See U. S. Patent 4,529,758 dated 16 July 1985) have also been reported. These materials are quite different frcm the silane compositions of the present invention. There is a need for a water based composition which is stable for a long period of time and which is highly effective as a masonry water repellant composition.
By the term "masonry" as used herein, is meant any porous inorganic substrate, particularly building compositions and including but not limited to structural ceramics such as common brick, paving brick, face brick, sewer pipe, drain tile, hollow block, terra cotta, conduits~ roofing tile, flue lining, cements and plastics such as Portland cement, calcined gypsum products, i.e., lding and building plaster and stucco, magnesia cement, insulation products such as electrical insulators, porcelain spark plugs, etc., and thermal insulators (diatomaceous earth brick). The present invention is particularly applicable to masonry, i.e., to all articles and architecural structures such as porous ceramic materials including stone, brick, tile, artificial stone, adobe, etc., and to ceramic articles, particularly masonry units, e.g., brick, pieces of stone, etc., which are generally held together or made a single mass by mortar, plaster or earth.
The masonry materials also include concrete and reinforced concrete such as found in roadways, bridge decks, airport runways, parking garage decks, and other concrete building structures.
The masonry materials which can be treated in accordance herewith are preferably dry when treated with the waterproofing compositions, although they may be wet. In the case of settable masonry materials, the compositions of the present invention may be incorporated in the preset mixture, for example, into a concrete mix prior to casting and setting.

~27789~

Briefly stated, the present invention is in an aqueous silane emulsion useful as a porous masonry water repellant composition which comprises (a) from about 1~ to about 40~ by weight of an alkoxysilane having the general formula Rn-Si-(R )4-n wherein R is a Cl-C20 hydrocarbyl or halogenated hydrocarbyl group, R is a hydrolyzable group such as Cl-C3 alkoxy, or halide, or amino, or carboxylate and n is 1 or 2, or dimers or trimers (oligomers) thereof, (b) from 0.5 to 50% by weight of the silane oomponent of an emulsifier ~aving an HLB value of from 4 to 15, and (c) water.
As indicated above, the water based compositions of the present invention include 1 to 40%, preferably 10 to 20~ by weight of (a) an alkoxysilane having the general formula of: Rn-Si-(R')4 n wherein R is a Cl-C20 hydrocarbyl group or halogenated hydrocarbyl group desirably a Cl-C10 alkyl group and preferably a C4-C10 alkyl group. The hydrocarbyl group consists of hydrogen and carbon atoms and may be aliphatic or alkyl (the latter being preferred), or cycloaliphatic or cycloalkyl, or aryl, or aralkyl. These hydrocarbyl radicals may also contain as substituent groups, halogen, e.g., chlorine, bromine, or fluorine, or nitrogen or oxygen or sulfur heteroatoms. One or more halogen substituents may be present in the R group. The R' group is a Cl-C3 alkoxy, halogen, amino, or carboxylate group. Thus, the alkyl groups useful as R' are methyl, ethyl, n-propyl, and isopropyl. As indicated, n may be 1 or 2 and thus, monohydrocarbyl substituted alkoxysilanes and dihydrocarbyl substituted alkoxysilanes are contemplated by the present invention. The active ingredients of the present invention do undergo hydrolysis to a sprprisingly small extent in the presence of ~27789~

water, and thus there may also be present in the compositions, either by intention or by accident, dimers and trimers, or other oligomers of the alkoxysilanes.
The second important ingredient is an emulsifier present in an amount ranging from 0.5 to 50~ by weight of the silane component.
These emulsifiers have an HLB value of from 4 to 15 and are generally of the polyhydroxy type. The third ingredient is water.

The ~vdrolYzable silanes The silanes useful in accordance with the present invention generally have a molecular weight in excess of 135 and preferably greater than 190 up to about 500 for the nomers. The dimers and trimers present in the composition will, of course, have multiply higher molecular weights than the single specie of silanes being used.
It should also be noted that mixtures of various silanes may be used, if desired.
Specific examples of silanes useful in accordance with the present invention include, therefore, methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, propyltriethoxysilane, propytridimethylaminosilane, propyltri-n-propoxysilane, butyltrimethoxysilane, butyltriethoxysilane, dibutyldimethoxysilane, isobutyltrimethoxysilane, isobutyltriacetoxysilane, di-isobutyldimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, 6-chloro-hexyl-trimethoxysilane,6,6,6-trifluorohexyltrimethoxysilane, cyclohexyltrimethoxysilane, benzyltrimethoxysilane, 4-chlorobenzyltriethoxysilane, 4-bromobenzyltri-n-propoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octyltrichlorosilane, octylmethyl-diisopropoxysilane, lauryltrimethoxysilane, 2-ethylhexyltrimethoxysilane, 4-chlorobenzyltrimethoxysilane, 127789~

decyltrimethoxysilane, dodecyltrimethoxysilane, dodecyltribromosilane, tetradecyltriethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, eicosyltrimethoxysilane, etc., alone and in admixture with the dimers, trimers and other oligomers thereof.

m e Emulsifiers A wide variety of ionic and nonionic emulsifiers have been tried and have been found to be useful in the present invention. m e desired emulsifiers are, however, nonionic and preferably polyhydroxy materials. Nonionic, anionic, cationic and ampholytic emulsifiers are well known from the state of the art. The concentration of the emulsifier used in accordance with the present invention may range from 0.5 to 50% by weight of the silane and preferably in the range from 1 to 20% by weight of the silane. The concentration and choice of emulsifier or emulsifier blend is highly dependent on the silane or silane mixture being used.
In general, those emulsifiers or emulsifier blends which have an HLB value in the range from about 2 to about 20, and preferably in the range from 4 to 15 may be used herein. The proper HLB value for a given silane or silane mixture must be determined experimentally in order to ascertain the optimum stability.
Specific examples of emulsifying agents which may be used in accordance herewith include the following with the HLB value given in parenthesis following the name. Sorbitantrioleate (1.8), sorbitantristearate (2.1), polyoxyethylene sorbitolhexastearate (2.6), glycerol nostearate (3.8), sorbitan nooleate (4.3), sorbitan nostearate (4.7), polyoxyethylene (2 mol) stearyl ether (4.9), sorbitan nopalmitate (6.7), polyoxypropylene mannitoldioleate (8), polyoxyethylene sorbitololeate (9.2), polyoxyethylene stearate (9.6), polyoxyethylene sorbitanmonooleate (10.0), polyoxyethylene nooleate ~7 -6-(11.4), polyoxyethylene (6 mol) tridecylether ~11.4), polyoxyethylene (10 mol) cetylether (12.9), polyoxyethylene sorbitan monooleate (15), polyoxyethylene (20 mol) stearylether (15.3), polyoxyethylene (15 mol) tridecylether (15.4), polyoxyethylene alkylamine (cationic, 15.5), polyoxyethylene alcohols having HLB of 9.7, about 10, and 11.6, ethoxylated nonylphenols having HLB values of 10, 11, and 12;
dialkylphenolethoxylates having a HLB value of 10.6, block copolymers of ethylene oxide and propylene oxide having a HLB values in the range 5.5 to 15, fatty acid glycerides having HLB values of approximately 4.
The preferred surfactants or emulsifiers are the "Spans"
which are sorbitan fatty acid esters having HIB values in the range from 4.3 to 8.6 and the Tweens 61 and 81 which are polyoxyethylene sorbitan fatty acid esters having HLB values in the range from 9.6 to 11.4. These preferred emulsifying agents maintain stable emulsions of the silanes for periods more than two months.
The following Table I lists various useful surfactants by class name and specific examples of commercial products.

~7789 Takle I

Polyoxyethylene aloohols Brij 30 (ICI AJnericas; 9.7) Tergitol 15-S-3 (Union Carbide approx. 10) Triton DF 16(Rohm ~ Haas; 11.6) .

Ethoxylated nonyl phenols NP-6 runion Carbide; 11) NP-7 runiOn Carbide; 12) C0-520 (G~F; 10) Dialkyl phenol ethoxylate DM-530 lGAF; 10.6) Block oopDly~ers of ethylene oxide Pluronics (BASF) and propylene oxide L42 (8~, L62 (7), L64 (15) L72 (6.5), L92 (5.5), 25R2 (6.3) TetroniC 702 (BASFi ?) Fatty acid glycerides Arlacel 165 (ICI Americas; 4) Sorbitan fatty acid e~bers Spans (ICI Americas) 2~ (8.6), 40 (6.7), 60 (4.7) 80 (~.3) Polyoxyethylene sorbitan 5ween~ 61 (ICI Americas; 9.6) fatty acld e~ters *
Tween , 81 (ICI Americas; 10.0) Atla~- G-1096 (ICI ~mericas; 11.4) Brij, Tergitol, Triton, Pluronic, Tetronic, Arlacel, Span, q~Ween and Atlas are all trademark~.

A

~277891 Table I - IContlnued) TYPE OE SD}eACTA~T EX~MeLES (SUPPLrER, HLB) Blends of sorbitan esters Atlas G-2090 (ICI Americas) with polyoxyethylene amines Amphoteric Atlas G-271 (ICI Americas) Polyvinylalcohol (Air Products and Chemicals, Inc.) The following specific example is illustrative of the manner of making the compositions of the present inventions.
To a magnetically stirred mixture of 20 grams of octyltriethoxysilane and 3 grams of Span 60 (sorbitan nooctadecanoate) (Chemical Abstract Registry Number 1338-39-2) obtained from ICI Americas was slowly added 77 grams of water producing a stable milky emulsion.
After standing for 3 weeks, the flash point was 180F.
20% solutions of the silane in mineral spirits and in isopropanol were prepared for comparison.
Concrete cubes two inches on the side were treated at the rate of 125 square feet per gallon with each mixture and allowed to cure at 72 and 50% relative humidity for two weeks. The blocks were then immersed in water, and after three weeks the weight gain was measured. The mineral spirits and the isopropanol alcohol silane solutions reduced the weight gain over an untreated control by 70% and an aqueous emulsion composition of the present invention reduced the weight gain also by 70%. This compares very favorably with the results obtained from solutions at similar concentrations of alkoxysilanes in other solvents such as mineral spirits, alcohol, etc. The extreme advantage is that the medium in which the silanes are carried is an aqueous medium having far more highly acceptable environmental impact than solvents now in commercial use.
As further examples of the practice of the present invention, concrete cubes 2 inches on the side were conditioned in a control room at 73F. and 50% relative humidity for 21 days to give a constant weight.

~Z77891 Each solution of masonry water repellant composition was applied to two cubes at the rate of 125 square feet per gallon (3.07 square meters per liter), and the coated cubes were cured on a rack in a control room for 13 days prior to recording the initial weight of each cube. All of the cubes including tw~ untreated control cubes were placed on a rack and Lmmersed in a distilled water bath. After 21 days of immersion, the cubes were removed, blotted dry and immediately weighed. The percent weight gain of each block was determined by Wfinal - Winitial X 100 = % Weight Gain Winitial The reductior. of weight gain was calculated by the formula:

100 X (~ Weiqht Gain of Control) - ~% Weiqht Gain of Sample) = Reduction of Weight Gain (% Weight Gain of Control) The higher reduction of weight gain values indicate re effective masonry water repellants.
The aqueous masonry water repellant emulsions were prepared as follows: In a four ounce bottle containing a magnetic stir bar were placed 10 grams of the silane (for a 20% emulsion) and 1.5 grams of the emulsifier (for a 3% loading). The mixture was vigorously stirred while 38.5 grams of water were added slowly over 5 to 10 minutes. Then the emulsion was stirred for an additional 20 minutes.
Emulsions prepared in this manner maintained a uniform milky appearance with little or no phase separation for several months.
Examples 1 to 6 are listed in Table 2 below.

lZ77891 I
H

H ff~ o'P t~ dP o'P ~P
~1 O O 15~ N O N
j ,c 1~

~ .~

3 H I v ~
~ ~ u o ~3 H F~ ¦ N N N ~
N ~ ~
~ ~ ~a~
5 ~ ~ ~P dP dP dP
U~ Z

J-~ ~1 ~
~ '~

.,, .,,.,, .,, .,, .,, .,, ~
~h ~ ~ ~ O
ZJJ ~ J~ V ~ J-H
'q 8 ~ 8 8 8 8 dP dP ~ dP ~OP 0 N N N NONO N E~
~ _ _ _ _ _ ~27q891 --ll--When isobutyltrimethoxysilane, octadecyltriethoxysilane, the tall oil fatty acid amide (~1~) f 3-aminop,opyltriethoxysilane, and 4R-triethoxysilylmenthene-l are emulsified in a manner indicated above and applied to concrete blocks, results similar to those obtained with octyltriethoxysilane as shown above are obtained.
The surprising feature of the compositlons of the present invention is that the degree of hydrolytic oondensation is so relatively lnw. It appears that the surfactants, especially the polyhydroxy type, e.g., the Spans and the Tweens, act as inhibitors of hydrolysis in the absence of an acid, or alkaline medium. However, in the acid or alkaline medium of the masonry, e.g., ooncrete, or the like, hydrolysis o3curs readily with the desired chemical bonding with the substrate then occurring. ~n the environment of use, the hydrolysis prooeeds readily with relatively slight evolution of the ~lcohol corresponding to the Cl-C3 alkyl group. Thus, the amaunt of volatile solvent material, e.g., ethanol or chemical reactant released to the atmosphere by the use of the oomQositions of the present inventi0 is severely restricted over that occurring with oolvents currently in -CP. However, as will be seen from the table of cesults given above, the di}ference in water repellancy from known ~ q~uDiti0~ i~ not too significant and well within experi~ental error.
as indicated above, the~e ccoQositions may ~e applid bo nYY#X~ry substrates such a~ concrete highways, concrete b,ridge decks, concrete runw~ys, ooncrete gar~ge dbcks, ooncrete side~olks, ~nd the like, in the ~a~e nanner a-D dilosed in the pabe~t to Seiler 3,772,065, s4pra. A1JD~ ~B indicatd ~bove, the comeo~itions of the pre~ent innention ~ay be ~pplid to dky nu~onry ~urfaoes or bD wet ~u~onry Jurf~oes without apparent ch~nge in the effectivene3s of the oc~po~ition~ as ~ater repellant agents.
Cther ingre~ients Jay be present in the oompositions hereof ~uch a~ antidcrobial~, antifung~ nticorro~ion agent~, lubricant~, d Dran an~ fragranoe , th1ckening ~qen, ~bc., In ~inDr a ountr inJuffici~nt to ~d~r~ ly affect the badc oo podtlons, e.g., fr~o~
0.1~ tD 5% by ~elght.

.
...... r ''

Claims

1. An aqueous silane emulsion composition useful to render masonry water repellant which is substantially free from an alcohol or other organic solvent and consists essentially of (a) from 1% to 40% by weight of an hydrolyzable silane having a molecular weight of up to about 500 and the general formula;
Rn - Si - (R')4-n wherein R is a C1-C20 hydrocarbyl or halogenated hydrocarbyl group, R' is C1-C3 alkoxy or halide or amino or carboxyl group, and n is 1 or 2, or oligomers thereof, (b) from 0.5 to 50% by weight of the silane component of an emulsifier having an HLB value of from 4-15, and (c) water.

2. An aqueous silane emulsion as defined in claim 1, wherein the silane is an alkylalkoxysilane.

3. An aqueous silane emulsion as defined in claim 1, wherein the silane is an alkyltrialkoxysilane.

4. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein R is a C1-C10 alkyl group, R' is a C1-C3 alkoxy group and n is 1.

5. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein R is a C4-C10 alkyl group.

6. An aqueous silane emulsion composition according to claim 1, 2 or 3, wherein R is a hydrocarbyl or halo hydrocarbyl group of from 8 to 20 carbon atoms.

7. An aqueous silane composition according to claim 1, 2 or 3, wherein R is a hydrocarbyl or halo hydrocarbyl group of 8 to 20 carbon atoms and said emulsion has stability against phase separation for more than two months.

8. An aqueous silane emulsion as defined in claim 1, wherein the silane is octyltriethoxysilane.

9. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein the concentration of the silane is from 10%
to 20% by weight.

10. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein the emulsifier to a nonionic emulsifying agent.

11. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein the emulsifier is a nonionic polyhydroxy compound.

12. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein the emulsifier is a sorbitan fatty acid ester.

13. An aqueous silane emulsion as defined in claim 1, 2 or 3, wherein the emulsifier is a polyoxyethylene sorbitan fatty acid ester.

14. An aqueous silane emulsion as defined in claim 1, wherein the silane is isobutyltrimethoxysilane.

15. An aqueous silane emulsion as defined in claim 1, wherein the silane is octadecyltriethoxysilane.

16. An aqueous silane emulsion as defined in claim 1, wherein the silane is 4-R-triethoxysilylmenthene-1.

17. A process for increasing the resistance to penetration by aqueous media of masonry which comprises applying to the surface thereof an aqueous silane emulsion which is substantially free from an alcohol or other organic solvent and consists essentially of (a) from 1% to 40% by weight of a hydrolyzable silane having a molecular weight of up to about 500 and the general formula:
Rn - Si - (R')4-n wherein R is a C1-C20 hydrocarbyl or halogenated hydrocarbyl group, R' is C1-C3 alkoxy, halide, amino, or carboxylate, and n is 1 or 2, or oligomers thereof, (b) from 0.5 to 50%
by weight of the silane component of an emulsifier having an HLB value of from 4-15, and (c) water.

18. A ceramic material treated with an emulsion according to claim 1, 2 or 3.