WO2015042669A2

WO2015042669A2 - Method for the manufacture of water-repellent products

Info

Publication number: WO2015042669A2
Application number: PCT/BE2014/000050
Authority: WO
Inventors: Gino Sirejacob
Original assignee: Cormitec.B.V.B.A
Priority date: 2013-09-26
Filing date: 2014-09-26
Publication date: 2015-04-02
Also published as: WO2015042669A3; BE1021766B1

Abstract

Method for the manufacture of water-repellent products contain a binding agent containing a Ca, characterised in that, prior to the hardening of the products; the binding agent containing Ca is mixed with an aqueous emulsion which contains: A) polysiloxane; B) an alkyl alkoxysliane; C) an emulsifying agent, in which the alkylalkoxysilane/polysiloxane weight ratio is between 21 and 40.

Description

Method for the manufacture of water-repellent products

The invention refers to a method for the manufacture of water-repellent products. The manufacture of water-repellent products which include a binding agent comprising Ca has more often than not been investigated. However, no real solution has been found up until now by means of which a product can be produced simply, in the course of which the product always has water-repellent properties after its application. Furthermore, the products quickly lose their repellent properties with the present solution.

Prior art

US 4,394,355 (1983) describes the preparation of a mixture containing

lime/cement by the mixing together of lime/cement, water, organopolysiloxane and sand. Tests carried out using the organopolysiloxane of embodiment 1 of this document have shown that the repellent properties were very slight.

US 4704416 (1987) describes a water dispersible powder that comprises a water soluble polymer, as well as an organosilicon component. The organosilicon component is an organopolysiloxane, for example. No products could be obtained with satisfactory water-repellent properties by mixing this powder into a mixture containing cement. US5110684 (1992) describes a product containing gypsum that comprises a water- soluble silane coupling component, as well as a surface-active substance and determined polysiloxane. Such a gypsum product absorbs an enormous quantity of water after its immersion in water for 72 hours. US6492459 (2002) describes a stable cream or paste containing water which comprises an or gano silicone component, a tensioactive substance and an organic solvent. The smearing of such a cream along one side of a product comprising cement did not enable the complete product to be water-repellent. The transverse sides of the product which were not coated with the cream showed no water- repellent properties.

EP 2065431 relates to an aqueous dispersion comprising silane, siloxane, an emulsifying agent, as well as cationic surfactants. The dispersion is intended for impregnating a substrate. No reference at all is made to mixing such a dispersion with a calcium containing hydraulic binder before its hardening.

EP0342519 (corresponding to US4988470) relates structure of inorganic fibers which are bound the one to the other by means of silicone resin. The structure comprises 6% of cured silicone with respect to the total weight of the structure. No reference at all is made to the use of an aqueous silicone dispersion with cement before the hardening of said cement composition.

^' DEI 0203247 discloses a cream containing alkyl alkoxysilane, an polysiloxane, emulsifying agent and water. The cream is intended to be used for impregnating a face of a substrate for ensuring water repellent properties. The cream is not intended to be mixed with a calcium containing hydraulic binding agent before its hardening.

US4582874 discloses an aqueous emulsion containing silicone resin, an emulsifier and water., and the use of said emulsion for impregnating a product, after hardening of the cement.

US6294608 discloses an aqueous emulsion for impregnating a porous mineral building material, said emulsion having to comprise an aminosilane or siloxane. Tests carried out in example 8 of said document shows a drastic decrease of the mechanical properties when mixing an aqueous isooctyltriethoxysilane dispersion with a composition comprising a hydraulic binder before its hardening. The^■ presence of polysiloxane is considered in said document as the presence of polysiloxane impairs the mechanical properties, despite the fact that when used as coating, it enables to reduce the water absorption to less than 0.5% after immersion for 24hours. The dispersion disclosed in US6492459 when mixed to a binder before its hardening enables to obtain a product having a water absorption of 2.2% after immersion in water for 24hours, i.e. after only 1 day.

Such a water absorption is considered as too rapid, meaning possible problems in case of freezing, etc. The present invention has for aim to produce water repellent product comprising a step of mixing an aqueous emulsion to a mixture comprising a hydraulic binder before its hardening, while not impairing the mechanical properties of the product, and while having a reduced water absorption of less than about 1.3% after 24 hours and even less than about 2.2% after immersion in water after at least 7 days, i.e. a water repellent product having a very low water absorption rate.

Brief description of the invention

The invention refers to the manufacture of water-repellent products which are completely and lastingly water-repellent with no change to the normal

manufacturing method. The sole difference is the addition of additives to the water that is used.

Thus the invention refers to a method for the manufacture of water-repellent products containing at least a calcium containing hydraulic binding agent and at least one inert filler, in which, prior to the hardening of the calcium containing hydraulic binding agent , the calcium containing hydraulic binding agent containing Ca is mixed at least with water in which at least organopolysiloxane is dispersed by using a dispersal system to form an aqueous hardenable mixture, in which at least one product is shaped with the aqueous hardenable mixture, and in which the product shaped with the aqueous hardenable mixture is hardened , characterised in that prior to the hardening of the calcium containing hydraulic binding agent, said calcium containing hydraulic binding agent is mixed at least with an aqueous emulsion which contains:

A) polysiloxane "A" being a polymer or a copolymer having a weight average molecular weight comprised between 500 and 2000g/moL preferably comprised between 600 and 1400g/mol, said polymer or copolymer being formed by the polymerisation of units of the following general formula:

R l x Si(OR2)_y (OH)_z 0₍4*_y-_Z)/2 with Rl, which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

R2, which are different or the same as: an alkyl group with 1 to 3 carbon atoms;

x having in average a value comprised between 1.0 and 2.0

y having in average a value comprised between 0.7 and 2.0

z having in average a value of less than or equal to 1.0

with the proviso that x + y + z < or = 3.0,

in which this polysiloxane has advantageously a dynamic viscosity of less than 2000mPa.s,

B) alkyl alkoxysilane "B" selected from the group consisting of iso-octyl ethoxysilane, iso butyl ethoxysilane, n-octyl ethoxysilane and mixtures thereof ,

C) an emulsifying agent by means of which the polysiloxane and the

alkylalkoxysilane are finely dispersed as particles with a size of less than 1 micron in the water, in which the weight ratio between, on the one hand, the alkyl alkoxysilane "B" selected from the group consisting of iso-octyl ethoxysilane, iso butyl ethoxysilane, n-octyl ethoxysilane and mixtures thereof , and on the other hand the polysiloxane "A" is between 21 and 40, in which the aqueous emulsion has a dynamic viscosity smaller than lOmPa.s, preferably smaller than 5mPa.s, and ha which the quantity of aqueous emulsion used in the manufacture of the water repellent products is such that the dry weight content of polysiloxane "A" and alkyl alkoxysilanc "B" in the water repellent products after the hardening of the calcium containing hydraulic binding agent is comprised between 0.03% and 0.5%, preferably between 0.05% and 0.4%, most preferably between 0.1% and 0.2% .

In the method in accordance to the invention, the at least one product shaped with the aqueous hardenable mixture is advantageously, but preferably, hardened under a temperature comprised between 100°C and 250°C, preferably from 150^DC and 250°C, and under a pressure comprised between 3 10⁵ Pa and 20 10⁵ Pa, preferably between 6 10⁵ Pa and 15 10^s Pa. The method of the invention is thus preferably a method for producing autoclaved product containing calcium containing hydraulic binder, such as autoclaved concrete, autoclavedcellular or aerated concrete or autoclaved sand lime bricks. The method of the invention is thus applicable to the existing methods for manufachiring autoclaved concrete products, such as the methods disclosed in US2013/0087075 and EP2602234, given as example only.

According to a particularly advantageous method of the invention, the product shaped with the aqueous hardenable mixture is hardened in presence of water vapour at a temperature comprised between 150°C and 250°C, under a pressure comprised between 3 10⁵ Pa and 20 10⁵ Pa, for a period of 0.5 hour to 48hours , advantageously for a period of 2 hours to IShours.

The aqueous emulsion preferably contains silanol and is substantially free of alkyl alkoxysilane different from the alkyl alkoxysilane "B".

Characteristics of advantageous embodiments of the method in accordance with the invention are as follows:

- the aqueous emulsion is substantially free of organic solvents, such as ethanol, polyglycol, etc. Advantageously, the aqueous emulsion comprises less than 0.5 weight % organic solvents, said aqueous emulsion being preferably substantially free of organic solvents. Advantageously, the hardening of the calcium containing hydraulic binding agent is carried out in presence of an aqueous medium comprising less than 0.5% by weight organic solvents, said medium being preferably substantially free of organic solvents, and/or

- the aqueous emulsion intended to be mixed to the calcium containing hydraulic binding agent before its hardening contains more than 40 weight% of water, preferably more than 50 weight%. Prior to the addition of the aqueous emulsion to a mixture containing the binding agent containing Ca, the aqueous emulsion contains for example more than 70 weight%, more than 80 weight%, more than 90 weight% of water. According to specific embodiments the water content (in weight) of the aqueous emulsion is greater than 95%, such as greater than 98% or greater than 99%. and/or

- before, during and/or after mixing calcium containing hydraulic binding agent with an aqueous medium, but in any case before the hardening of the calcium containing hydraulic binding agent, the aqueous emulsion to be mixed to the calcium containing binding agent contains less than 1% by weight of

alkylalkoxysilane B, preferably less than 0.5% by weight, like between 0.05% and 0.25% by weight, and/or

- before the hardening of the calcium containing hydraulic binding agent, the calcium containing hydraulic binding agent is mixed with an aqueous medium free of alkyl lkoxysilane, prior its mixing with an aqueous medium comprising the alkyl alkoxysilane B, preferably the said emulsion, and/or

- the alkyl alkoxysilane B in the emulsion is selected from the group consisting of N-octyl triethoxysilane, iso-octyl triethoxysilane. and/or

- the emulsifying agent is a fatty acid, preferably a fatty acid with alkoxy groups, for example with alkoxy groups having 1 to 3 carbon atoms, in particular an ethoxylated fatty acid. Examples of emulsifying agents are given in US6492459 (see column 5, line 20 to column 6, line 29.) and/or

- the polysiloxane "A" is a polymer or a copolymer formed by the polymerisation of units of the following general formula:

Rl_x Si(0R2)_y (0H)₇ G(4-x-_y-z)/2 with Rl, which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

R2 is C₂H₅ ;

x having in average a value comprised between 1.2 and 1.6

y having in average a value comprised between 0.9 and 1.8

z having in average a value of less than or equal to 0.2

with the proviso that x + y + z < or = 3.0, and/or

- the pH of the emulsion is brought to 4 - 9. Prior to the mixing of the emulsion with the binding agent containing Ca, the pH of the emulsion is preferably between 4 and 6. The pH of the emulsion is advantageously controlled by adding a weak organic acid, preferably citric acid, and/or

- the calcium containing hydraulic binding agent is a hydraulic binding agent selected from the group consisting of cement, calcium oxide, calcium hydroxide and rnixtures thereof, and/or

- in a first stage particles containing sand or silicon oxide are mixed with an aqueous medium comprising the emulsion and possibly one or more inert fillers not containing silicon to form an aqueous mixture containing silicon oxide, but free or substantially free of calcium containing hydraulic binding agent, whilst in a second stage, possible after an intermediate stage of adding various inert additives and/or inert solid particles to the said aqueous mixture containing silicon oxide, at least one calcium containing hydraulic binding agent, possibly premixed with one or more inert fillers and/or premixed with an aqueous medium, is mixed, before its hardening, with said aqueous mixture containing silicon oxide to form a hardenable mixture, in which after a moulding stage to produce a shape with the hardenable mixture, the shape with the hardenable mixture is hardened, and/or

- a hardenable mixture of at least the emulsion, particles containing silicon oxide and a binding agent containing Ca is moulded by casting or pressing in a mould or moulding pattern or using an extrusion mould to produce at least one shaped product or partly hardened shaped product, preferably partially hardened products, whereby these shaped product(s) or partially hardened shaped products are further hardened outside the moulding pattern or mould or extrusion mould. This further hardening is advantageously carried out under pressure (for example at a pressure of 1 to 50 10⁵ Pa, preferably between 2 and 25 10⁵ Pa, such as 5, 10, 15 and 20 10^s Pa) and/or at a temperature of 25 °C to 250°C , preferably between 50°C and 200°C. The hardening or further hardening can also be carried out at room temperature (under pressure or otherwise). It has also been remarked that the removal of the pressed products from the mould was easier and that the risk of adherence of not completely hardened pressed products was reduced, and/or

- a method which is characterised by the fact that, in a first stage the calcium containing hydraulic binding agent is mixed with an aqueous emulsion to form an aqueous binding mixture, whilst in a second stage, before the hardening of the calcium containing hydraulic binding agent, possibly after an intermediate stage of adding various inert additives and/or inert solid particles to the aqueous binding mixture, a mixture containing silicon oxide particles possibly mixed with water is mixed with the aqueous binding mixture to form an aqueous hardenable binding containing mixture, in which after a moulding stage to produce at least one shaped product with the aqueous hardenable binding containing mixture, the so shaped product is hardened, and/or

- a method which is characterised by the fact that in a first stage substantially dry calcium containing hydraulic binding agent is mixed with sand or particles containing silicon oxide to form a substantially dry binding mixture, whilst in a second stage, possibly after an intermediate stage of adding various additives or solid particles or water, said substantially dry binding mixture is mixed with an aqueous emulsion to form an aqueous hardenable binding containing mixture, in which after a moulding stage to produce a shaped product with said aqueous hardenable binding containing mixture, said shaped product is hardened advantageously at least partly, preferably substantially completely in the mould, and/or

- the shaped product(s) is partly hardened in the mould for a time sufficient for achieving a sufficient cohesion of the shaped product(s) enabling a removal thereof from the mould while keeping the shape of the shaped product(s). and/or - the product shaped with the aqueous hardenable mixture is hardened at a temperature comprised between 105°C and 200°C. and/or

- the product is shaped with the aqueous hardenable mixture by casting or pressing in a mould or moulding pattern or by an extrusion mould to produce at least one partially hardened product, said at least one partially hardened product being further hardened outside the mouldmg pattern or mould or extrusion mould, advantageously at room temperature.

The method in accordance with the invention preferably has more than two of these characteristics and details.

The invention also refers to an aqueous emulsion containing a polysiloxane which is ready to be thinned with water without further additives (i.e. water that contains no additive) by the simple addition of this water on stirring thereafter, by means of which a thinned, homogeneous emulsion containing polysiloxane A and alkyl alkoxysilane B is formed, in which the emulsion has one or several of the characteristics of the aqueous emulsion, which is used in the method in accordance with the invention.

The aqueous emulsion containing polysiloxane contains:

A) polysiloxane "A" being a polymer or a copolymer having a weight average molecular weight comprised between 500 and 2000g/mol, preferably comprised between 600 and 1400g/mol_} said polymer or copolymer being formed by the polymerisation of units of the following general empirical formula: Rl_x Si(OR2)y (OH)_z 0_(4-x-y-z)/2 with Rl, which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

x having in average a value comprised between 1.0 and 2.0 y having in average a value comprised between 0.7 and 2.0

z having in average a value of less than or equal to 1.0

with the proviso that x + y + z < or = 3.0,

C) an emulsifying agent by means of which the polysiloxane and the

alkylalkoxysilane are finely dispersed as particles with a size of less than 1 micron in the water, in which the weight ratio between, on the one hand, the alkyl alkoxysilane "B" selected from the group consisting of iso-octyl ethoxysilane, iso butyl ethoxysilane, n-octyl ethoxysilane and mixtures thereof , and on the other hand the polysiloxane "A" is between 21 and 40, and

D) water,

in which the aqueous emulsion has a dynamic viscosity smaller than 1 OmPa.s, preferably smaller than 5mPa.s.

Preferably more than 95% (advantageously more than 97%, preferably more than 99%) by weight of this emulsion in accordance with the invention consists of components A, B, C and D. The aqueous emulsion preferably contains silanol, and is advantageously substantially free of alkyl alkoxysilane different from the alkyl alkoxysilane "B", as well as being preferably substantially free of polysiloxane different from polysiloxane "A". Characteristics of an advantageous emulsion in accordance with the invention are as follows:

- the aqueous emulsion is virtually free of organic solvents such as ethanol, polyglycol, etc. Advantageously, the aqueous emulsion comprises less than 0.5 weight % organic solvents, said aqueous emulsion being preferably substantially free of organic solvents. Advantageously, the hardening of the calcium containing hydraulic binding agent is carried out in presence of an aqueous medium comprising less than 0.5% by weight organic solvents, said medium being preferably substantially free of organic solvents, and/or

- the aqueous emulsion contains less than 70 weight%, preferably less than 60 weight%, preferably less than 50 weight% of water. For example, the emulsion is advantageously a concentrated emulsion containing between 10 and 40% weight% water, and/or

- the aqueous emulsion contains more than 0.5 eight%, preferably more than lweight%, for example between 1 and 5 weight% alkylalkoxysilane B. and/or

- the alkyl alkoxysilane B in the emulsion is selected from the group consisting of N-octyl triethoxysilane, iso-octyl triethoxysilane.. and/or

- the emulsifying agent is a fatty acid, preferably a fatty acid with alkoxy groups, for example with alkoxy groups having 1 to 3 carbon atoms, in particular an ethoxylated fatty acid. Examples of emulsifying agents are given in US6492459 (see column 5, line 20 to column 6, line 29) and/or

Rlx Si(OR2)_y (OH)_z 0₍4-x_-y-z)/2 with Rl, which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

R2 is C₂H₅ ;

x having in average a value comprised between 1.2 and 1.6

y having in average a value comprised between 0.9 and 1.8

z having in average a value of less than or equal to 0.2

with the proviso that x + y + z < or = 3.0, and/or

- the pH of the emulsion is between 3 - 9, preferably between 3 and 6. The pH of the emulsion is advantageously brought to 4 - 9, preferably between 4 and 6. The emulsion comprises advantageously one or more weak organic acids, preferably citric acid for controlling the pH. Details and characteristics of the invention will proceed from the following specification in which reference is made to the appended drawing.

This drawing schematically shows a method in accordance with the invention.

Examples of emulsions in accordance with the invention

Emulsions in accordance with the invention are prepared by the mixing of various components. These emulsions are ready to be thinned with water without the addition of extra additives to the water.

The following components are used for the preparation of these emulsions:

Al) polysiloxane with units which have the following average empirical formula:

CH₃ Si (OC₂H₅)o,8 Ou

With an average molecular weight of approximately 600-70Qg/mol and a viscosity of approximately 20mm²/s

A2) polysiloxane with units which have the following average empirical formula: (CH₃)_{1 :}2 Si (OC₂H₅)i,s Oo,5 With an average molecular weight of approximately 900- 1 OOOg/mol and a kinetic viscosity of approximately 20nrm²/s (and a dynamic viscosity smaller than 20 mPa.s)

A3) polysiloxane with units which have the following average empirical formula:

(CH₃)i,5 Si (OC₂II₅)o,9 O With an average molecular weight of approximately 80Q-900g/mol and a viscosity of approximately 20mm²/s (and a dynamic viscosity smaller than 20 mPa.s) A4) polysiloxane with units which have the following average empirical formula: iCri₃) Si (OC₂H₅)u Oo,8

With an average molecular weight of approximately 800-900g/mol and a kinetic viscosity of approximately 20rrrm²/s (and a dynamic viscosity smaller than 20 mPa.s)

A5) polysiloxane with irnits which have the following average empirical formula: N¾ (CH₂ )₅ Si (OC₂H₅)o,8 O_u

With an average molecular weight of approximately 600-700g/mol and a kinetic viscosity of approximately 20mm /s (and a dynamic viscosity smaller than 20 mPa.s)

A6) polysiloxane with units which have the following average empirical formula:

(CF₃ (CF₂)₅)_1..2 Si (OC₂H₅)_lj8 Oo,5 With an average molecular weight of approximately 900- 1 OOOg/mol and a kinetic viscosity of approximately 20mm²/s (and a dynamic viscosity smaller than 20 mPa.s)

A7) polysiloxane with units which have the following average empirical formula:

(CF₃ (CF₂)₇)₁₍₅ Si (OC₂H₅)c, 9 O_u With an average molecular weight of approximately 1000-1200g/mol and a kinetic viscosity of approximately 20mm²/s (and a dynamic viscosity smaller than 20 mPa.s)

A8) polysiloxane units which have the following average empirical formula:

(CF₃ (CF2)7)i,2 Si (OC₂H₅)i_j2 Oo,8 With an average molecular weight of approximately 1000-12Q0g/mol and a kinetic viscosity of approximately 20mm²/s (and a dynamic viscosity smaller than 20 mPa.s)

Bl) isooctyltriethoxysilane

B2) N-octyltriethoxysilane

B4) isobutyliriethoxysilane

CI) fatty acids with 12 to 16 carbon atoms

C2) alkyl (with 12 to 18 carbon atoms) amines containing ethylene oxide groups, Dl) citric acid to regulate the pH between 4 and 6

The emulsion also comprises a small quantity of ethanol which is formed by hydrolysis, (less than 0.5% by weight of the weight of the emulsion)

Examples of emulsions are given in the following tables:

Silres (R) BS Creme C cream (pH of about 7- 7.5) contains at most 80% by weight of a mixture of octyltriethoxysilane and organopolysiloxane with units which have the following average empirical formulae:

CH₃ Si (OC₂H₅)o_;s Ο, ι In this Silres cream the octyltriethoxysilane/organopolysiloxane ratio is smaller than about 10.

In a first series of comparative tests, lOOg of this cream is mixed with lOOg of isooctyltriethoxysilane and lOOg water to obtain a liquid emulsion. This emulsion will subsequently be used for carrying out tests.

In a second series of comparative tests, lOOg of this cream is mixed with 150g of isooctyltriethoxysilane and lOOg of water to obtain a liquid emulsion.

A method in accordance with the invention will now be described with reference to Figure 1.

The emulsion in accordance with the invention is initially thinned using water. This takes place in the tank 1 for example.

Tank 2 is a tank for the lime whilst tank 3 is intended for the sand.

A machine 4 is used to dose the raw materials and feed them to a mixing tank 5.

The mixing of all raw materials is carried out in the mixing tank 5. The mixing of all raw materials was easier. A homogeneous mixture was achieved more quickly. The reaction of the raw materials also starts in this mixing tank.

The mixture is conveyed to a sand-lime brick press 6 to form bricks. The Imocking out of the bricks from the press was easier.

The bricks thus moulded are subsequently placed in an oven 7 (at a temperature of 100°C to 200°C) for steam autoclaving the bricks.

The bricks thus moulded and hardened (steam autoclaved) had the following characteristics: - Water absorption of less than 5 weight% (such as less than 2% by weight) after immersion of the bricks in a water bath (20°C) for more than 5 days, and even for more than 30days.

- All sides of the bricks are homogeneously water-repellent.

After cutting a brick in two, the cut sides are homogeneously water- repellent.

- Better resistance against frost,

substantially no fissure along the faces

- ^' substantially the same mechanical properties than a product prepared with the same method, but without adding the emulsion to the water (for example the mechanical properties - such as the compression strength - of the product achieved by a method of the invention is comprised between 95 - 105% the mechanical properties of the product prepared by using the same ingredients, but without the emulsion, with the same parameters of the method);

- 6 months after producing the bricks, the bricks were still water-repellent.

Homogeneous distribution of the water-repellent properties inside the products

- resistance against the growth of fungi, algae

- better protection of steel reinforcements inside of the product

- low water absorption ( less than 4% by weight) after placing the water repellent product in a water bath at a temperature of 25° C for more than 1 month, advantageously for more than 3 months (water height above the upper face of the product being at least 50cm, advantageously more than

100cm).

Comparison tests have shown that by using emulsions with an alkylalkoxysilane/ polysiloxane weight ratio of 10 or of 70, the hardened bricks had reduced water- repellent propertie s . Comparison tests have shown that when using for example 1% by weight of emulsion in the method, instead of less than 0,5% by weight, mechanical properties - such as compressive strength - were reduced by more than 10%. Still for comparative tests, products were prepared by mixing dry cement (Portland cement - 1 part by weight) and sand (3 parts by weight) with about (1/2 part by weight of water). Said products had a rectangular shape (20cmx4cm) with a - thickness of 3cm. In said tests, the following emulsions were tested when added at a rate of 0.5%o of the weight of cement and sand :

Emulsion EMI of US6294608

Emulsion EMU ofUS6294608

Emulsion comparative 1 (ECl) : 60% Bl, 5%> emulsifying agent CI

Emulsion comparative 2 (EC2) : 60% Bl, 10% A3, emulsifying agent CI

Emulsion comparative 3 (EC3): 10% A3, emulsifying agent CI

Emulsion n°21 of the invention. (HSfV)

The water absorption of the product after immersion in a water bath after 1 , 2, 7 and 30 days (water height of 50cm above the upper face of the product) is given inthe following table : water absorption after

1 day 2days 7 days 30 days

EMI about 2.5% about 3% about 4%

EMU about 2.7% about 3.3% about 4.5%

ECl about 2.6% about 3.1% about 4.2%

EC2 about 2.5% about 3.0% about 4%

EC3 about 3% about 3.5% about 4.6%

Control about 6% about 10% about 10% about 11 %

INV about 1.2% about 1.3% about 2.2%o about 3.1% As it can be seen from the table, the water absorption rate is drastically reduced in the product of the invention. The man skilled in the art was unable to predict such a drastic reduction of the water absorption rate for the water repellent product.

It was also observed that the emulsion of the invention were quite stable, as only no phase separation was observed after a 6 month storage time at 20°C, as well as a temperature of 0°C, and as the composition was still effective after 18 months, advantageously after a shaking operation.

It was also observed that when using the emulsion of the invention as coating composition of a product not prepared with the method of the invention, only a very thin water repellent layer was formed, said water repellent layer was quickly scratched with abrasive paper.

Autoclaved concrete products have been prepared as follows :

Autoclaved aerated concrete product A was prepared by dry mixing the following components : 15kg Portland cement, 15 kg lime (CaO), 70kg silica sand, and lOOg Alumina powder. Water was mixed with a quantity of emulsion 21 so that weight content in alkyl alkoxysilane and polysiloxane in the water is about 0.3%. The emulsion 21 and the water are stirred vigorously, so that the particle size of the emulsion is well below 1 micron, about 0.1-0.3μηι.

100kg of the dry mix was mixed with about 60kg of the aqueous medium. When the mixture was homogeneous, it was poured into moulds.

When sufficiently stiff, the bricks were removed from the moulds and placed in an oven. The bricks were then cooked at a temperature of about 180°C, under a water vapour atmosphere with a pressure of about 10 10⁵Pa, for about 12 hours. The end autoclaved product were water repellent, while having a very low content of alkyl alkoxysilane and poly siloxane. Mechanical properties of the autoclaved bricks with the emulsion were substantially equal to the mechanical properties of the autoclaved bricks prepared with water not containing the emulsion.

Autoclaved aerated concrete products B, C and D have been prepared by a method similar to the method used for method A, except that the emulsion 21 was replaced by emulsion 15, emulsion 8 and a mix (50%/50%) of emulsion 15 and emulsion 8, respectively.

Emulsion of the invention can be simply added to water to be used in the example of US2013/0087075 for imparting water repellence, as well for ensuring a very low water absorption after 24hours immersion in a water bath, as well as after more than 7 days immersion in a water bath, with respect ^'to the product prepared without adding emulsion to the water to be mixed with the dry mix (cement, lime, sand, etc.)..

Claims

1. A method for the manufacture of water-repellent products containing at least a calcium containing hydraulic binding agent and at. least one inert filler, in which, prior to the hardening of the calcium containing hydraulic binding agent , the calcium containing hydraulic binding agent containing Ca is mixed at least with water in which at least one organopolysiloxane is dispersed by using a dispersal system to form an aqueous hardenable mixture, in which at least one product is shaped with the aqueous hardenable mixture, and in which the product shaped with the aqueous hardenable mixture is hardened , characterised in that prior to the hardening of the calcium containing hydraulic binding agent, said calcium containing hydraulic binding agent is mixed at least with an aqueous emulsion which contains:

A) polysiloxane "A" being a polymer or a copolymer having a weight average molecular weight comprised between 500 and 2000g/mol, preferably comprised between 600 and 1400g/mol, said polymer or copolymer being formed by the polymerisation of units of the following general formula:

R l x Si(OR2)_y (0II)₂ 0₍4-x-y-z)/₂ with Rl, which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

x having in average a value comprised between 1.0 and 2.0

y having in average a value comprised between 0.7 and 2.0

z having in average a value of less than or equal to 1.0

with the proviso that x + y + z < or = 3.0,

in which this polysiloxane has advantageously a dynamic viscosity of less than 2000 mPa.s, B) alkyl alkoxysilane "B" selected from the group consisting of iso-octyl ethoxysilane, iso butyl ethoxysilane, n-octyl ethoxysilane and mixtures thereof , C) an emulsifying agent by means of which the polysiloxane and the

alkylalkoxysilane are fmely dispersed as particles with a size of less than 1 micron in the water, in which the weight ratio between, on the one hand, the alkyl alkoxysilane "B" selected from the group consisting of iso-octyl ethoxysilane, iso butyl ethoxysilane, n-octyl ethoxysilane and mixtures thereof , and on the other hand the polysiloxane "A" is between 21 and 40, in which the aqueous emulsion has a dynamic viscosity smaller than l mPa.s, preferably smaller than S Pa.s, and in which the quantity of aqueous emulsion used in the manufacture of the water repellent products is such that the dry weight content of polysiloxane "A" and alkyl alkoxysilane "B" in the water repellent products after the hardening of the calcium contairiing hydraulic binding agent is comprised between 0,03% and 0.5%, preferably between 0.05% and 0.4%, most preferably between 0.1% and 0.2% .

2. Method in accordance with claim 1, in which the at least one product shaped with the aqueous hardenable mixture is hardened under a temperature comprised between 100°C and 250°C, preferably from 150°C and 250°C, and under a pressure comprised between 3 10⁵ Pa and 20 10⁵ Pa, preferably between 6 10⁵ Pa and 15 10⁵ Pa.

3. Method in accordance with claim 1 or 2, characterised in that the aqueous emulsion comprises silanol and is substantially free of alkyl alkoxysilane different from the alkyl alkoxysilane "B".

4. Method in accordance with anyone of the previous claims, characterised in that the aqueous emulsion comprises less than 0.5 weight % organic solvents, said aqueous emulsion being preferably substantially virtually free of organic solvents, and in which the hardening of the calcium contairiing hydraulic binding agent is carried out in presence of an aqueous medium comprising less than 0.5% by weight organic solvents, said medium being preferably substantially free of organic solvents .

5. Method in accordance with one of the previous claims, characterised in that the aqueous emulsion intended to be mixed to the calcium containing hydraulic binding agent before its hardening contains more than 40 weight%, preferably more than 50 weight% of water.

6. Method in accordance to claim 5 , characterised in that before, during and/or after mixing calcium containing hydraulic binding agent with an aqueous medium, but in any case before the hardening of the calcium containing hydraulic binding agent, the aqueous emulsion to be mixed to the calcium containing binding agent contains less than 1 weight% alkylalkoxysilane B.

7. Method in accordance to any one of the preceding claims, in which before the hardening of the calcium containing hydraulic binding agent, the calcium contairiing hydraulic binding agent is mixed with an aqueous medium free of alkylalkoxysilane, prior its mixing with an aqueous medium comprising the alkyl alkoxysilane B, preferably the said emulsion.

8. Method according to anyone of the preceding claims, in which the alkyl alkoxysilane B in the emulsion is selected from the group consisting of N-octyl triethoxysilane, iso-octyl triethoxysilane,

9. Method in accordance with one of claims 1 to 6, characterised in that the polysiloxane "A" is a polymer or a copolymer formed by the polymerisation of units of the following general formula: l x Si(OR2)_y (OH)_z 0_(4-x-y-z)/2 with R 1. which are different or the same as: alkyl group met 1 to 10 carbon atoms, which is possibly substituted by one or more halogen atoms and/or N¾ groups;

R2 is C₂II₅ ;

x having in average a value comprised between 1.2 and 1.6

y having in average a value comprised between 0.9 and 1.8

z having in average a value of less than or equal to 0.2

with the proviso that x + y + z < or = 3.0.

10. Method in accordance with one of the preceding claims, characterised in that the emulsifying agent is a fatty acid, preferably a fatty acid with alkoxy groups with 1 to 3 carbon atoms, in particular an ethoxylated fatty acid.

11. Method in accordance with one of the previous claims, characterised in that the pH of the emulsion is brought to 4 - 9, preferably between 4 and 6 by adding a weak organic acid, before mixing the emulsion with the calcium containing hydraulic binding agent.

12. Method in accordance with the previous claim, characterised in that the pH of the emulsion is between 4 and 6.

13. Method in accordance with one of the previous claims, characterised in that in a first stage sand or particles containing silicon oxide are mixed with an aqueous medium comprising the emulsion and possibly with one or more inert fillers not containing silicon to form an aqueous mixture containing a silicon oxide, but free of calcium containing hydraulic binding agent, whilst in a second stage, possibly after an intermediate stage of adding various inert additives and/or inert solid particles to said aqueous mixture containing silicon oxide, at least one calcium containing hydraulic binding agent, possibly premixed with one or more inert fillers and/or premixed with an aqueous medium, is mixed, before its hardening, with said aqueous mixture containing silicon oxide to form a hardenable mixture, in which after a moulding stage to produce a shape with the hardenable mixture, the shape with the hardenable mixture is hardened.

14. Method in accordance with one of the preceding claims 1 to 12, characterised in that in a first stage the calcium containing hydraulic binding agent is mixed with an aqueous emulsion to form an aqueous binding mixture, whilst in a second stage, before the hardening of the calcium containing hydraulic binding agent, possibly after an intermediate stage of adding various inert additives and/or inert solid particles to the aqueous binding mixture, a mixture containing silicon oxide particles possibly mixed with water is mixed with the aqueous binding mixture to form an aqueous hardenable binding containing mixture, in which after a moulding stage to produce at least one shaped product with the aqueous hardenable binding containing mixture, the so shaped product is hardened.

15. Method in accordance with one of the preceding claims 1 to 12, characterised in that in a first stage substantially dry calcium containing hydraulic binding agent is mixed with sand or particles containing silicon oxide to form a substantially dry binding mixture, whilst in a second stage, possibly after an intermediate stage of adding various additives or solid particles or water, said substantially dry binding mixture is mixed with an aqueous emulsion to form an aqueous hardenable binding containing mixture, in which after a moulding stage to produce a shaped product with said aqueous hardenable binding containing mixture, said shaped product is hardened.

16. Method in accordance with one of the preceding claims, in which the product shaped with the aqueous hardenable mixture is hardened in presence of water vapour at a temperature comprised between 150°C and 250°C, under a pressure comprised between 3 10⁵ Pa and 20 10⁵ Pa, for a period of 0.5 hour to 48hours , advantageously for a period of 2 hours to 15hours.

17. Method in accordance with one of the preceding claims, in which the product is shaped with the aqueous hardenable mixture by casting or pressing in a mould or moulding pattern or by an extrusion mould to produce at least one partially hardened product, said at least one partially hardened product being further hardened outside the moulding pattern or mould or extrusion mould.

18. Liquid emulsion containing polysiloxane which is ready to be thinned with water without further additives by the simple addition of this water and subsequent stirring, by means of which a thinned homogeneous emulsion containing polysiloxane is formed, in which the emulsion containing polysiloxane has one or more 1 of the characteristics of the aqueous emulsion which are described in any one of the previous claims.