HK1033950A - Storage-stable water-repellent composition for masonry materials - Google Patents

Description

Storage-stable water-repellent composition for masonry materials

The present invention relates generally to storage stable water-resistant compositions for masonry products. The composition combines a relatively water insoluble hydrolyzable silane and a hydrogen functional polysiloxane in the form of an aqueous emulsion.

The benefits of using water-repellent compositions to protect masonry materials are well known. "masonry" as used herein means any porous inorganic substrate, especially a construction composition, which includes structural ceramics such as ordinary bricks, paving bricks, face bricks, sewage pipes, drainage tiles, hollow bricks, terracotta, water pipes, roof tiles, cement and plastics such as portland cement, calcined gypsum products, molded articles and construction plasters, stucco for decoration, magnesia cement, insulating articles such as electrical insulators and natural or man-made stones. These materials readily absorb ambient moisture due to porosity in the untreated condition. Subsequent exposure to freezing temperatures causes cracking, leading to cracking and spalling. In masonry materials used for the construction of roads and bridges, water-repellent coatings are also used to protect masonry materials from the damaging effects of salts and similar anti-icing agents.

Us reissue patent 33,759 discloses compositions in the form of aqueous emulsions that impart water resistance to masonry materials. The compositions described herein consist essentially of a hydrolysable silane or oligomer thereof, an emulsifier having a Hydrophobic Lipophilic Balance (HLB) of from 4 to 15 and water. When we prepared these compositions we found that they suffer from the disadvantage that they have only limited storage stability and deteriorate on heating.

U.S. patent 5,110,684 also describes water-repellent compositions for masonry comprising a mixture of an emulsion of a water-soluble silane coupling agent and a hydrogen-functional polysiloxane. However, this composition also has the disadvantage that it has a very limited storage time.

Thus, there remains a need for water-resistant compositions that are storage stable for use with masonry products.

Our invention is a highly effective composition for imparting water-repellent properties to masonry materials. It can be conveniently applied as a coating on the surface of a masonry substrate or it can be mixed as an additive with a settable masonry material such as concrete or calcined gypsum prior to setting.

The water-repellent compositions claimed herein include aqueous emulsions having both a continuous aqueous phase and a discontinuous silicone phase. Our aqueous emulsions were prepared from components including: (A) general formula R_n-Si-R＇_(4-n)Wherein n is a number of 1 to 2 and R is C₅-C₂₀Monovalent hydrocarbon radicals and R' is C₁-C₄An alkoxy group; (B) having at least two silicon-bonded hydrogen atoms per molecule, at least 5 siloxy units per molecule and a kinematic viscosity at 25 ℃ of 0.5X 10^-6And 1, 000X 10^-6m²Hydrogen functional polysiloxanes between/sec; (C) an emulsifier; and (D) water. The discontinuous silicone phase herein comprises components (A) and (B) and the continuous aqueous phase comprises water. The ratio of components (A) to (B) in the silicone phase should be such that our emulsions still exhibit physical and chemical stability when stored at room temperature for 6 months or at 50 ℃ for 6 weeks. The silicone phase is present in the aqueous emulsion in an amount of from 10 to 75% by weight.

The term "stable" as used herein with respect to our water-resistant emulsion compositions includes two phenomena: 1) physical stability and 2) chemical stability.

The water-resistant emulsion compositions claimed are of the oil-in-water type and are physically unstable when broken. The suspended droplets that make up the discontinuous silicone phase (also referred to as the oil phase or dispersed phase) will coalesce and thus be effectively removed from the suspension of the continuous aqueous phase. The difference in density between these phases results in the formation of two well-defined liquid layers. Thus, physically stable emulsions must maintain a uniform appearance over time.

The emulsion may remain physically stable but not necessarily chemically stable. Chemical instability over time or heat is clearly demonstrated when the ability of the composition to repel moisture (whenever applied to masonry decking) is severely compromised. It is believed that chemical instability occurs when the silicone phase of the emulsion undergoes significant hydrolysis and condensation (or partial curing) prior to initial application to the masonry material.

The chemical and physical stability measurements were made by simply observing the appearance and performance characteristics of a given water-resistant emulsion as a function of storage time at room temperature. However, the aging test is easily accelerated by heating. Those of ordinary skill in the art will recognize that storage of a water-resistant emulsion at 50 ℃ for 1 week is generally equivalent to storage at room temperature for 1 month. Thus, "physically stable" as used herein means that the emulsion remains unbroken when stored at room temperature for at least 6 months or at 50 ℃ for 6 weeks. Likewise, "chemically stable" as used herein means that the emulsion exhibits at least 60% water repellency ("% WE") as determined by modified National Cooperative high way Research program protocol 244(NCHRP 244) after 6 months of storage at room temperature or 6 weeks at 50 ℃. Our modified NCHRP244 is identical in all respects to that of NCHRP244, except that the water repellency test was performed on a mortar cube, 2 inches (5.08 cm) on one side and 4 inches (10.16 cm) on the opposite side.

The composition of the present invention forms an excellent waterproof barrier in the form of a resin coating when applied to masonry materials. The curing of the composition is then catalyzed by the residual alkali of the masonry material. The present invention has found that surprisingly good heat and storage stability is obtained. It is believed that these stabilities are due to the incorporation of the water-insoluble alkoxysilane and hydrogen-functional polysiloxane in the discontinuous silicone phase of the aqueous emulsion.

It is therefore an object of the present invention to provide a water repellent composition in the form of an emulsion suitable for use with masonry materials, while exhibiting physical and chemical stability.

It is another object of the present invention to provide such a composition which, at least as well as the prior art compositions, provides moisture removal for masonry materials.

More preferably, the present invention provides physically and chemically stable compositions for imparting water-repellent properties to masonry materials. The composition comprises: (A) a water-insoluble alkoxysilane; (B) a hydrogen functional polysiloxane; (C) an emulsifier and (D) water. This composition is in the form of an aqueous emulsion comprising a continuous aqueous phase and a discontinuous silicone phase. When the composition contacts masonry materials, the water-insoluble alkoxysilane and hydrogen-functional polysiloxane hydrolyze and condense with each other and with the hydroxyl groups in the masonry, thus forming a resinous water-repellent network. The hydrolysis and condensation reactions can be catalyzed by the latent alkalinity of the masonry material.

Component (A) is of the formula R_n-Si-R＇_(4-n)Wherein n is a number of 1 to 2 and R is C₅-C₂₀Monovalent hydrocarbon radicals and R' is C₁-C₄An alkoxy group.

For component (A), the term "water-insoluble" means that less than 1g of silane is soluble in 100g of water. This is an important distinction between the compositions of the present invention and the prior art. It is believed that the use of water soluble silane coupling agents is the root cause of the limited pot life of the compositions of US patent 5,110,684. Water-soluble silane coupling agents undergo rapid hydrolysis and condensation when contacted with water. We have unexpectedly allowed the introduction of silanes into the discontinuous silicone phase in our aqueous emulsion using water insoluble alkoxysilanes. This avoids hydrolysis and condensation of the alkoxysilane until the silane is in direct contact with the masonry material.

In the general formula of component (A), R is C₅-C₂₀A monovalent hydrocarbon group. In using a low carbon content hydrolyzable silane, the silane tends to be water soluble. However, if some groups such as amino groups are introduced, even at C₅-C₂₀Hydrocarbyl groups within the range can also impart water solubility to our alkoxysilanes. Thus, R may be unsubstituted or substituted with various groups, but the only requirement is that such groups do not cause the alkoxysilane to become water soluble.

Since the R groups in the above formula also play an important role in the ability of the composition to repel moisture in order to impart hydrophobicity to our cured compositions. Generally, the higher the carbon content of the R group, the more hydrophobic it will impart to the final cured coating. Nevertheless, having C₂₀The alkoxysilanes of the R group generally approach the upper commercially available limit. Surprisingly, we have found that it is preferred that R is n-octyl because it imparts good hydrophobicity, resulting in a very stable emulsion. However, it should be noted that R may be a straight or branched chain alkyl, aryl or arylalkyl.

R' is limited to C₁-C₄Alkoxy groups, because higher carbon content in alkoxy groups tends to be less reactive. The value of n is a number between 1 and 2, and most preferably 1. Trialkoxysilanes are preferred because they form a three-dimensional resin network. Nevertheless, it should be recognized that dialkoxysilanes, and mixtures thereof with trialkoxysilanes, can also be successfully used. Those of ordinary skill in the art will recognize that oligomeric hydrolysis products of the above-described alkoxysilanes may also be used.

The most preferred compound for use as component (A) is n-octyltriethoxysilane. Component (B) according to the invention is a polymer having at least two silicon-bonded hydrogen atoms per molecule, at least 5 siloxy groups per molecule and a kinematic viscosity at 25 ℃ of 0.5X 10^-6And 1, 000X 10^-6m²Between/sec and preferably 10X 10^-6And 100X 10^-6m²Hydrogen functional polysiloxanes in/sec. Component (B) may be a linear, branched or cyclic siloxane or combination thereof, which includes alkyl, aryl and arylalkyl groups in addition to silicon-bonded hydrogen. Thus, suitable compounds (having the degree of polymerization necessary to remain within the specified viscosity range) include alkyl methyl/methyl-hydrogen siloxane copolymers and methyl-hydrogen siloxane.

If the kinematic viscosity of component (B) is less than 0.5X 10-6m at 25 DEG C²Sec, it is too volatile to function effectively in our claimed composition. In other words, when the composition is applied to masonry surfaces, the hydrogen-functional siloxane tends to volatilize before hydrolyzing and condensing into a resin matrix. If the viscosity of component (B) is greater than 1,000X 10 at 25 DEG C^-6m²Sec, our coating composition is not effective in wetting the porous surfaces of masonry materials. Most preferred for efficient pore penetration is a trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer having three methylhydrogensiloxy groups and five dimethylsiloxy groups. A low cost alternative to component (B) is a trimethylsiloxy-terminated methyl-hydrogen linear siloxane having sixty methylhydrosiloxy groups.

Component (C) of the present invention is an emulsifier. Ionic, nonionic and amphoteric emulsifiers may be used in the compositions of the present invention, with nonionic polyoxyethylene lauryl ethers being preferred. Generally, the amount of emulsifier is from 1% to 20% of the combined weight of components (A), (B) and (D).

The amount will, of course, depend on the potency of the particular surfactant. Typically, the amount of emulsifier (C) is 1-3 wt% of the other remaining components. Emulsifiers having an HLB value in the range of 2 to 20 can be used with high efficiency. Preferably, the emulsifier has an HLB value in the range of 4-17, which tends to produce a more stable emulsion. Those skilled in the art will recognize that blends of various emulsifiers may also be used.

Component (D) is water and is preferably deionized or distilled water.

When mixing components (a) to (D), it is preferred that silicone components (a) and (B) are premixed, after which components (C) and (D), i.e., emulsifier and water, are added and mixed in any order. In fact, when component (B) (hydrogen-functional polysiloxane) has a relatively low molecular weight (e.g., a trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer having three methylhydrogen siloxy groups and five dimethylsiloxy groups), it must be blended with component (A) a water-insoluble alkoxysilane before being blended with (C) an emulsifier and (D) water. Otherwise, the emulsifier composition of the present invention cannot be produced. Preferably, component (C) is separately mixed with component (D). Thereafter, two mixtures (A)&B and C&D) Combine and mix in a single container for 30 minutes. Finally, the mixture obtained is passed once through a homogenizer (at 7, 500psi or 5.17X 10⁷pa) or in two passes through the sonaltor (at 1, 400psi or 9.65X 10⁶pa) to produce the emulsion of the invention.

When component (B) is a higher molecular weight hydrogen-functional polysiloxane (e.g. with sixty methylhydrogensiloxy groups and a viscosity of 30X 10)^-6m²Trimethylsiloxy-terminated methylhydrogen linear siloxane,/sec), all of components (A) - (D) can be added to a vessel and mixed. Emulsification is enhanced by shaking and using a homogenizer or subjecting the mixture to ultrasonic energy.

The discontinuous silicone phase comprises from 10 to 75% by weight of the aqueous emulsion, but preferably from 40 to 60% by weight of said aqueous emulsion.

The ratio of components (A) to (B) should be such that the emulsion still shows physical and chemical stability when stored at room temperature for 6 months or at 50 ℃ for 6 weeks.

When the molecular weight of component (B) is relatively low (e.g.a trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer having three methylhydrogensiloxy groups and five dimethylsiloxy groups), the weight ratio of component (A) to component (B) is preferably from 10: 90 to 90: 10. When the molecular weight of component (B) is relatively high (e.g., a trimethylsiloxy-terminated methylhydrogen linear siloxane having sixty methylhydrogen oxy groups), the weight ratio of component (A) to component (B) is preferably 1: 3.

However, it is believed that a weight ratio of component (A) to component (B) of greater than 90: 10 will result in an emulsion that exhibits both chemical and physical stability, particularly when the pH of the emulsion is maintained between 4 and 5. A pH value within this range suppresses hydrolysis and condensation of components (a) and (B) in the silicone phase. This can be easily achieved by adding a weaker acid such as glacial acetic acid to the emulsion.

Various features and advantages of the present invention will be illustrated by the following examples. For examples 1-5 and comparative examples 1-3, the percent water removal ("% WE") of the emulsions can be determined using a 5.08X 5.08 cm cube made according to ASTM C109 cast from III mortar using a modified National Cooperative high Research Program 244Protocol (NCHRP 244). The depth of penetration can be measured by breaking a sample piece that has been treated and then contacting the broken surface with a 1% solution of the sulfanazo 111 dye. The penetration depth corresponds to the depth of absence of dirt measured on the fracture surface.

Example 1

Here, 0.8 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30, available from ICI Americas, Inc & Wilmington, Delaware), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35, also available from ICI Americas, Inc.) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 36g of a kinematic viscosity of 10X 10 having three methylhydrogensiloxy groups and five dimethylsiloxy groups^-6m²Trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer/sec and 4g of n-octyltriethoxysilane were mixed for 5 minutes and stirred. Mixing was continued for an additional 30 minutes, and the resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gives an oil-in-water emulsion with an average particle size of 400 nm.

The% WE (percent water removal) conferred by the fresh emulsion was 84. The fresh emulsion penetrated the swatch to a depth of 3.5 mm. The emulsion was then stored for aging at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted by it was 80.7.

Example 2

Next, 0.8 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 20g of a kinematic viscosity of 10X 10 having three methylhydrogensiloxy groups and five dimethylsiloxy groups^-6m²Trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer/sec and 20g of n-octyltriethoxysilane were mixed for 5 minutes and then stirred. Mixing was continued for an additional 30 minutes, and the resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gives an oil-in-water emulsion with an average particle size of 400 nm.

The% WE imparted by the fresh emulsion was 80.5 and the emulsion penetrated the swatch to a depth of 6 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted by it was 80.8.

Example 3

An emulsion composition was prepared in the same manner as in example 1 except that the amount of polyoxyethylene (4) lauryl ether was reduced to 0.6 g (from 0.8 g).

The% WE imparted by the fresh emulsion was 83.4 and the emulsion penetrated the swatch to a depth of 4.5 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted was 83.6. The aged emulsion penetrated the swatch to a depth of 5 mm.

Example 4

1.45 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 20g of a kinematic viscosity of 10X 10 having three methylhydrogensiloxy groups and five dimethylsiloxy groups^-6m²Trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer/sec and 20g of n-octyltriethoxysilane were mixed for 5 minutes and then stirred. Mixing was continued for an additional 30 minutes, and the resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gave an oil-in-water emulsion having an average particle size of 400 nm.

The% WE imparted by the fresh emulsion was 89 and the emulsion penetrated the swatch to a depth of 3.5 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted by it was 77.5.

Example 5

Next, 0.8 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 4g of a mixture having three methylhydrosiloxy groups and five dimethylsiloxy groups and a kinematic viscosity of 10X 10^-6m²Trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer/sec and 36g of n-octyltriethoxysilane were mixed for 5 minutes and then stirred. Mixing was continued for an additional 30 minutes, and the resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gave an oil-in-water emulsion having an average particle size of 400 nm.

The% WE imparted by the fresh emulsion was 84.5 and the emulsion penetrated the swatch to a depth of 6.3 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted by it was 82.8.

Comparative example 1

Thereafter, 0.8 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 40g of n-octyltriethoxysilane were added and mixing continued for an additional 30 minutes. The resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer.

The% WE imparted by the fresh emulsion was 78.2 and the emulsion penetrated the swatch to a depth of 5 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken, but the% WE imparted by it was only 28.5. Thus, the absence of any hydrogen-functional polysiloxanes in the formulation will result in a chemically unstable composition.

Comparative example 2

Subsequently, 0.8 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) 72% aqueous solution and 58.3 g of deionized water were mixed for 15 minutes. 40g of propyltrimethoxysilane were then added and mixing was continued for a further 30 minutes. The resulting mixture was then mixed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gives an aqueous emulsion having an average particle size of 400 nm.

The% WE imparted by the fresh emulsion was 50 and the emulsion penetrated the swatch to a depth of 1 mm. The fresh emulsion was not aged. Thus, the absence of hydrogen functional polysiloxanes and the use of propyltrimethoxysilane (not belonging to the water insoluble alkoxysilanes defined herein for component (a)) in the formulation does not result in a composition with acceptable water resistance.

Comparative example 3

Further, 0.6 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 1.1 g of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij) 35) 72% aqueous solution and 58.3 g deionized water were mixed for 15 minutes. Thereafter, 20g of n-octyltriethoxysilane was added and mixing continued for 30 minutes. Subsequently, 20g of a mixture having three methylhydrogensiloxy groups and five dimethylsiloxy groups and a kinematic viscosity of 10X 10 were added^-6m²Trimethylsiloxy terminated dimethyl/methylhydrogen linear siloxane copolymer/sec, mixing was continued for an additional 30 minutes. Finally, the resulting mixture is then processed at 7, 500psi or 5.17X 10⁷Pa next pass through the homogenizer. This gives an aqueous emulsion having an average particle size of 400 nm.

The% WE imparted by the fresh emulsion was 80.8 and the emulsion penetrated the swatch to a depth of 5.5 mm. The fresh emulsion was then stored aged at 50 ℃ for 6 weeks. The aged emulsion remained unbroken and the% WE imparted by it was 30.2. The penetration depth of the aged emulsion was 1 mm. These results were compared with those of example 2. It can then be seen that when a lower molecular weight, hydrogen-functional polysiloxane is used as component (B), it is necessary to blend components (A) and (B) before adding (C) and (D). Failure to mix these components in the necessary order may produce a composition that lacks chemical stability.

Example 6

157.5 g of a mixture having sixty methylhydrogensiloxy groups and a kinematic viscosity of 30X 10^-6m²Trimethylsiloxy-terminated methylhydrogen linear siloxane per sec, 52.5 g of n-octyltriethoxysilane, 4.2 g of polyoxyethylene (4) lauryl ether (HLB = 9.7, Brij  30), 19.5 g of a 28% aqueous solution of polyoxyethylene (23) lauryl ether (HLB = 16.9, Brij  35) and 116.3 g of deionized water were stirred in a vessel. The vessel contents were shaken for a few minutes and then divided into 40g batches in each jar. The tip of the ultrasonic probe was then placed 3/8 inches (1cm) below the liquid level in the center of each jar. The probe was energized to a set point between 40-55% (the ultrasonic processor was rated at 475 watts maximum power) and the mixture was treated under these conditions for 30 seconds. The emulsion formed within a few seconds after probe energization, as evidenced by the milky appearance formed and retained. From eachThe probe was removed from the jar, capped, and the mixture shaken for 10-15 seconds and then placed in a stream of cold tap water for 1 minute to cool the jar and its contents. The probe was reinserted as before and energized for an additional 30 seconds. The lid was attached and the jar shaken again and then cooled as before. This process was repeated several times, requiring the contents of each jar to be treated with an ultrasonic probe for a total of 2.5 minutes. The contents of the jars are then combined and mixed to form a single composition. The composition consists of 60 wt% of an aqueous, oil-in-water emulsion in which the oil phase consists of 75 wt% polymethylhydrosiloxane and 25 wt% n-octyltriethoxysilane. The weight ratio of n-octyltriethoxysilane (A) to hydrogen-functional polysiloxane (B) is 25: 75. The average particle size of the discontinuous silicone phase was 435 nm.

250g of the emulsion prepared are diluted in 5 kg of water and placed in a tank. This gave a bath with a silicone content of 3% by weight. A pre-weighed composite board (which comprises cured cement and cellulose fibers, having dimensions of 320X 120X 8mm, manufactured by Duralite Corporation of Guategla) was soaked in the bath for a period of 12 seconds. The panels were removed from the bath, allowed to stand for 2 minutes to allow the surface water to dissipate, and then reweighed. The difference in weight before and after soaking was used to calculate the amount of diluted silicone emulsion absorbed by the board, which was 5.9 wt% of the dry weight of the board.

The plate was then dried for 7 days and weighed again. The dried board was then soaked in a water bath for 2 hours at a depth of 20 inches (50.8 cm), removed, drained and reweighed as appropriate, and the weight percent of water absorbed was determined to be 1.9 wt%.

This test was repeated with the second plate and the amount of silicone emulsion absorbed was 5.7 wt%. The amount of water absorbed after the first treatment was determined to be 1.8 wt%.

Finally, the emulsion was stored at room temperature and observed periodically over a period of one year. It has been found to have physical stability that does not change over time (i.e., remains unbroken).

Example 7

An emulsion similar to example 6 was prepared by the following method: 33.4 g of a polyoxyethylene (23) lauryl ether solution (BRIJ  35, 72% active ingredient in water) was first mixed in a 2 quart (1.9 liter) jar for 30 minutes in 547.0 g of hot (60 ℃) tap water to form a solution. 225g of n-octyltriethoxysilane, 675g of a mixture having three methylhydrogensiloxy groups and five dimethylsiloxy groups and a kinematic viscosity of 10X 10^-6m²Trimethylsiloxy-terminated dimethyl/methylhydrogen linear siloxane copolymer per sec, 18g of polyoxyethylene (4) lauryl ether (BRIJ  30) and 1.6 g of glacial acetic acid. The contents of the jar were stirred for 1 hour to form a dispersion. The liquid was then sonicated by pumping the dispersion into a stainless steel cylinder equipped with an inlet and outlet and equipped with an ultrasonic horn. The liquid flowing from the sonicator had the appearance of a milky white liquid and was collected in another jar. When the whole feeding process is finished, the whole feeding process is allowed to pass through the ultrasonic device for the second time. The composition consisted of a 60% aqueous active emulsion and a discontinuous silicone phase (active phase) consisting of 75% by weight of trimethylsiloxy terminated methyl-hydrogen linear siloxane and 25% n-octyltriethoxysilane. The silicone phase of the emulsion had an average particle size (light scattering using a NIACOMP  370 submicron particle sizer) of 563nm, with 99% of the particles being less than 1420nm, and the emulsion also contained 0.18% acetic acid, based on the active ingredient.

Two cement panels were treated and tested using the same procedure as described in example 6. The weight percent of silicone emulsion absorbed by the two panels was 6.3 and 6.4 wt%, respectively. The uptake of water was 2.4 and 2.5 wt.%.

Finally, the emulsion was stored at room temperature and observed periodically over a period of one year. During this period the emulsion remains unbroken. Thus, when higher molecular weight hydrogen-functional polysiloxanes are used as component (B), premixing of silicone component (a) and component (B) does not appear necessary. Comparative example 4

An emulsion similar to that of example 6 was prepared in a similar manner except that it contained only n-octyltriethoxysilane and no hydrogen-functional polysiloxane. 13.4 g of polyoxyethylene (23) lauryl ether solution (BRIJ  35L, 72% active ingredient in water) was then blended with 218.0 g of hot (60 ℃) tap water and stirred in a 2 quart (1.9 liter) jar for 30 minutes to form a solution. Next, 360g of n-octyltriethoxysilane, 7.2 g of polyoxyethylene (4) lauryl ether (BRIJ  30) and 0.7 g of glacial acetic acid were added. The contents of the jar were stirred for 1 hour to form a dispersion. The liquid was then sonicated by pumping the dispersion into a stainless steel cylinder equipped with an inlet and outlet and equipped with an ultrasonic horn. The liquid flowing from the sonicator had the appearance of a milky white liquid and was collected in another jar. When the whole feeding process is finished, the whole feeding process is allowed to pass through the ultrasonic device for the second time. The composition consisted of a 60% active water emulsion. The discontinuous silicone phase (active phase) consisted primarily of n-octyltriethoxysilane. The emulsion has an average particle size (NIACOMP  370 submicron particle sizer) of 514nm, 99% of the particles being smaller than 1447nm, and also contains 0.2% acetic acid, based on the active ingredient.

Two cement panels were treated and tested using the same procedure as described in example 6. The weight percent of silicone emulsion absorbed by the two panels was 6.1 and 6.2 wt%, respectively. The uptake of water was 2.9 and 4.8 wt.%.

Finally, the emulsion was stored at room temperature and observed periodically. The emulsion broke after only 1 week. Thus, since no hydrogen functional polysiloxanes are included in the formulation, a physically unstable emulsion is obtained.

As is clear from the foregoing examples 1 to 7, the aqueous emulsions prepared according to the present invention exhibit excellent water-repellent properties, even when diluted. Moreover, the very outstanding physical and chemical stability exhibited by the emulsions of the present invention is clearly demonstrated when the% WE of the heat aged emulsions of examples 1-5 is compared to the results of comparative examples 1-4 and the aged results of examples 6 and 7 are compared to the results of comparative example 5.

Those skilled in the art will recognize that the novel compositions of the present invention can be used to provide a cured water-repellent coating on the surface of a masonry substrate by coating the surface of the substrate with the composition and allowing the composition to cure. In a similar manner, the compositions of the present invention can be blended with settable masonry compositions such as mortar or gypsum, also imparting water-resistance to the set composition.

Claims (12)

1. A storage stable composition comprising an aqueous emulsion comprising a continuous aqueous phase and a discontinuous silicone phase; the emulsion can be formulated from the following components:

(A) having the formula R_n-Si-R＇_(4-n)Wherein n is a number of 1 to 2 and R is C₅-C₂₀Monovalent hydrocarbon radicals and R' is C₁-C₄An alkoxy group.

(B) Having at least two silicon-bonded hydrogen atoms per molecule, at least five siloxy units per molecule and a kinematic viscosity at 25 ℃ of 0.5×10^-6And 1, 000X 10^-6m²Hydrogen functional polysiloxanes between/sec;

(C) an emulsifier; and

(D) the amount of water is controlled by the amount of water,

the discontinuous silicone phase comprises components (a) and (B) and the continuous aqueous phase comprises water;

the components (A) and (B) being present in the silicone phase in a weight ratio of (A) to (B) such that the emulsion is physically and chemically stable after storage for six months at room temperature or for six weeks at 50 ℃; and

the silicone phase is present in the aqueous emulsion in an amount of from 10 to 75 wt%.

2. A composition according to claim 1, wherein component (B) is a compound having three methylhydrosiloxy groups and five dimethylsiloxy groups and having a kinematic viscosity of 10X 10^-6m²Trimethylsiloxy terminated dimethyl/methylhydrogen linear siloxane copolymer per sec.

3. A composition according to claim 1, wherein component (B) is a compound having sixty methylhydrogensiloxy groups and a kinematic viscosity of 30X 10^-6m²Trimethylsiloxy terminated methylhydrogen linear siloxane per sec.

4. A composition according to claim 2, wherein the weight ratio of components (A) to (B) is from 10: 90 to 90: 10.

5. A composition according to claim 3, wherein the weight ratio of components (A) to (B) is 1: 3.

6. A composition according to claim 1, wherein the emulsifier component (C) has an HLB value of from 2 to 20.

7. The composition according to claim 1, wherein the emulsifier is polyoxyethylene lauryl ether.

8. The composition of claim 1 further comprising an acid in an amount sufficient to maintain the pH of the composition between 4 and 5.

9. A method of making a storage stable composition comprising an aqueous emulsion comprising a continuous aqueous phase and a discontinuous silicone phase, comprising the steps of:

(I) blending the following components:

(A) having the formula R_n-Si-R＇_(4-n)Wherein n is 1 to 2

R is C₅-C₂₀Monovalent hydrocarbon radicals and R' is C₁-C₄An alkoxy group; and

(B) having at least two silicon-bonded hydrogen atoms per molecule, at least five siloxy units

Element/molecule and kinematic viscosity at 25 ℃ of 0.5X 10^-6And 1, 000X 10^-6m²Of/sec

Meta hydrogen functional polysiloxanes; and

(II) blending the blend obtained in step (I) with the following components:

(C) an emulsifier; and

(D) water; and then

(III) emulsifying the mixture obtained in step (II) to form said emulsion, wherein said discontinuous silicone phase comprises components (a) and (B) and the continuous aqueous phase comprises component (D) water;

the components (A) and (B) being present in the silicone phase in a weight ratio of (A) to (B) such that the emulsion is physically and chemically stable after storage for six months at room temperature or for six weeks at 50 ℃; and

the silicone phase is present in the aqueous emulsion in an amount of from 10 to 75 wt%.

10. An article comprising a masonry substrate exposed to at least one surface coated with a storage stable composition according to any one of the preceding claims 1 to 9.

11. A method for providing a masonry substrate with a cured water-repellent coating, the substrate exposing at least one surface, the method comprising coating the surface with the aqueous emulsion of any one of claims 1 to 9.

12. A method for providing water-repellent properties to a settable masonry composition, the method comprising admixing the settable masonry composition with the aqueous emulsion of any one of claims 1-9.