IMPREGNATION CREAM, USE AND METHOD FOR PREPARING THE IMPREGNATION CREAM

Abstract

The invention relates to an impregnation cream. The impregnation cream contains water, at least one emulsifier and at least one polydimethylsiloxane selected from: HO—(SiMe.sub.2O).sub.n—H and Me.sub.3SiO—(SiMe.sub.2O).sub.n—SiMe.sub.3, wherein n is an integer from 20 to 2500, wherein the impregnation cream is free of hydrocarbons, alkoxylated silanes, alkoxylated siloxanes and amine group-functionalized siloxanes.

Claims

1. An impregnation cream comprising: water, at least one emulsifier and at least one polydimethylsiloxane selected from: HO—(SiMe.sub.2O).sub.n—H and Me.sub.3SiO—(SiMe.sub.2O).sub.n—SiMe.sub.3, wherein n is an integer from 20 to 2500, the impregnation cream being free from hydrocarbons, alkoxylated silanes, alkoxylated siloxanes and amine group-functionalized siloxanes.

2. The impregnation cream of claim 1, consisting of: water, at least one emulsifier and at least one polydimethylsiloxane selected from: HO—(SiMe.sub.2O).sub.n—H and Me.sub.3SiO—(SiMe.sub.2O).sub.n—SiMe.sub.3, wherein n is an integer from 20 to 2500, and optionally at least one additive, a total amount of the additives, based on the total mass of the impregnation cream, being less than 5% by mass.

3. The impregnation cream of claim 1, wherein the emulsifier is an alkoxylated emulsifier having an HLB value of at least 9.

4. The impregnation cream of claim 1, wherein the emulsifier has an HLB value of at least 10.

5. The impregnation cream of claim 1, wherein the emulsifier is isotridecyl alcohol polyglycol ether.

6. The impregnation cream of claim 1, wherein an amount of the emulsifier, based on the total mass of the impregnation cream, is 0.3 to 3 mass %.

7. The impregnation cream of claim 1, wherein n in the formulae shown in claim 1 is an integer from 50 to 1800.

8. The impregnation cream of claim 1, wherein the viscosity of the polydimethylsiloxane at 25° C. is in a range from 20 to 350,000 mm.sup.2/s.

9. The impregnation cream of claim 1, wherein a proportion of the polydimethylsiloxane, based on the total mass of the impregnation cream, is 50 to 92 mass %.

10. A method for preparing an impregnation cream of claim 1, comprising the steps of: mixing the water and the at least one emulsifier until a homogeneous mixture is formed; and admixing the at least one polydimethylsiloxane into the homogeneous mixture until a homogeneous whitish-colored cream is formed.

11. A method of impregnating mineral building materials, the method comprising applying the impregnation cream of claim 1.

Description

EXAMPLES

[0028] In the following, the present invention will further be described with reference to the examples.

Examples—Preparation of Impregnation Creams

Example 1

[0029] 18.4 g of water and 0.8 g of the emulsifier isotridecyl alcohol-polyglycol ether were weighed into a mixing beaker. It was shaken for about 5 minutes until the droplets disappeared and a clear liquid was obtained.

[0030] Then, 35.1 g of a hydroxyl-terminated polydimethylsiloxane having a viscosity of about 50,000 mm.sup.2/s at 25° C. (any polydimethylsiloxanes are available, for example, from Gelest) was added.

[0031] The mixture was homogenized for 5 minutes at 15,000 rpm using a rotor-stator stirrer from IKA. A low-viscosity milk was formed.

[0032] Another 36.3 g of the polydimethylsiloxane was then added and again homogenized for 5 minutes at 15,000 rpm.

[0033] Consistency of the impregnation cream became creamy, but still remained flowable.

[0034] Finally, another 34.6 g of the polydimethylsiloxane was added and again homogenized for 5 minutes at 15,000 rpm.

[0035] A stable, whitish-colored cream was obtained. After storage at room temperature for 12 months, no change of the stable consistency was observed.

Example 2

[0036] The method of preparation of Example 1 was repeated, but the dosage of the emulsifier was doubled and the hydroxyl-terminated polydimethylsiloxane having a viscosity of 50,000 mm.sup.2/s was replaced by a hydroxyl-terminated polydimethylsiloxane having lower viscosity of 100 mm.sup.2/s at 25° C.

[0037] Again, a stable, whitish-colored cream was obtained. After 12 months of storage at room temperature, no change of the stable consistency was observed.

Example 3

[0038] The method of preparation of Example 1 was repeated, but the hydroxyl-terminated polydimethylsiloxane having a viscosity of 50,000 mm.sup.2/s was replaced by a hydroxyl-terminated polydimethylsiloxane having a viscosity of 5,000 mm.sup.2/s at 25° C.

[0039] A stable, whitish-colored cream was obtained. After 12 months of storage at room temperature, no change of the stable consistency was observed.

Example 4

[0040] An impregnation cream was again prepared as described in Example 1, but the hydroxy-terminated polydimethylsiloxane having a viscosity of 50,000 mm.sup.2/s was replaced by a trimethylsiloxy-terminated polydimethylsiloxane having a viscosity of about 10,000 mm.sup.2/s at 25° C.

[0041] Any trimethylsiloxy-terminated polydimethylsiloxanes can be obtained from Thermo Fisher Scientific—Alfa Aesar.

[0042] Again, a stable, whitish-colored cream was obtained. After 12 months of storage at room temperature, no change of the stable consistency was observed.

Example 5

[0043] The method of preparation of Example 4 was repeated, but the trimethylsiloxy-terminated polydimethylsiloxane having a viscosity of 10,000 mm.sup.2/s was replaced by a trimethylsiloxy-terminated polymer having a viscosity of 50 mm.sup.2/s at 25° C.

[0044] Again, a stable, whitish-colored cream was obtained. After 12 months of room temperature storage, no change of the stable consistency was observed.

Examples—Applicability of Impregnation Creams

Example A: Coating of Brickstones

[0045] 5 brickstones having the dimensions of 20.5 cm×13.5 cm×5.5 cm were coated using the impregnation creams of Examples 1 to 5.

[0046] For this purpose, a rectangle having side lengths of 10 cm and 8 cm was marked in the center of one surface of each brick (20.5 cm×13.5 cm), with the longer side of the marked rectangle aligned parallel to the longer side of the brickstone.

[0047] In each case, 10 g of the impregnation creams of Examples 1 to 5 were applied onto the marked rectangle.

[0048] Before application of the impregnation creams, the brickstones had been stored for 2 days on the floor surface (20.5 cm×13.5 cm) immersed in a 1 cm layer of water. Even after application of the impregnation creams, this storage in water was consistently continued.

[0049] After a storage period of 2 and 5 weeks, respectively, the bricks were removed from the water bath and cut in half using a hammer and chisel.

[0050] Water droplets were pipetted onto the fractured surfaces to evaluate whether the droplets were absorbed by the surface or whether beads were formed that would retain their shape and not be absorbed even during prolonged storage.

[0051] The possible formation of water beads was to be considered as an evidence that hydrophobization of the inner area of the brick had taken place.

[0052] It was observed that beads were formed at the upper edge, where the coating was applied, and that underneath, on the entire fracture surface, there was flow and absorption of the water pipetted thereon.

[0053] The width of the upper bead-forming zone was different for the 5 brickstones.

[0054] The width of the upper bead-forming zone was dependent on the coating with the respective cream of Examples 1 to 5 and the duration of water storage as follows.

[0055] After two weeks of water storage, the following results were obtained:

[0056] Zone width when coated using the impregnation cream of example 1: 5 mm.

[0057] Zone width when coated using the impregnation cream of example 2: 10 mm.

[0058] Zone width when coated using the impregnation cream of example 3: 5 mm.

[0059] Zone width when coated using the impregnation cream of example 4: 3 mm.

[0060] Zone width when coated using the impregnation cream of example 5: 15 mm.

[0061] Following this test, water storage of one half of each cut brickstone was continued. The other half was stored under dry conditions.

[0062] After additional water storage of one half of the cut brickstone for another 3 weeks, the brickstone was cut again and water droplets were pipetted onto the respective fracture surfaces.

[0063] The following upper zone widths were detected on the fractured surfaces, where water beads formed, wherein, below these bead-forming zones, the water pipetted thereon was again immediately absorbed by the brick surface.

[0064] Zone width when coated using the cream of example 1: 10 mm

[0065] Zone width when coated using the cream of example 2: 15 mm

[0066] Zone width when coating with the cream of example 3: 10 mm

[0067] Zone width when coated using the cream of example 4:10 mm

[0068] Zone width when coated using the cream of example 5: 30 mm

[0069] After another 6 months of water storage or dry storage, the dimensions of the bead-forming zones turned out to remain unchanged after both dry storage and water storage.

[0070] From these results, it can be concluded that by coating the brickstones with the polydimethylsiloxane impregnation creams of the present invention, a water-repellent effect was obtained in the edge zones.

Example B—Coating of Hollow Concrete Blocks

[0071] Cube-shaped hollow blocks having an edge length of 19 cm were used for coating with the impregnation creams of Examples 1 to 5.

[0072] Four of the six side faces were sealed with a 3.5 cm thick concrete wall, two opposite side faces were open.

[0073] The hollow concrete blocks were stored in water while being seated on one of the four concrete walls. The water height was 1 cm, and the duration of water storage was 2 days. The respective hollow block was thus immersed in water with one base plate and with the two opposite side walls 1 cm. The upper top plate remained dry.

[0074] Dark coloring of the vertical side walls progressed from the bottom up to a height of approx. 12 cm.

[0075] After the 2-day water immersion, the upper cover plate was coated using the impregnation creams of Examples 1 to 5 in a zone width of 6 cm.

[0076] The rectangular coating zone with side lengths of 19 and 6 cm was located at the edge of the upper cover plate directly above an underlying side wall. The respective quantity of the impregnation creams applied was approx. 35 g.

[0077] Water storage was then continued. After a storage period of 6 months, the respective hollow block was removed from the water bath and evaluated for the original dark coloring of the vertical side walls.

[0078] It was found that the dark coloring of the side wall, which had risen from below and was immediately under the coating zone, had decreased from a height of 12 cm to a height of 4 cm downwards.

[0079] In addition, there was another dark coloring that extended downward from the top, where the coating was applied to the top sheet, to a sidewall height of 8 cm, the entire sidewall had darkened from the top to a wall height of 8 cm.

[0080] The other, opposite side wall was unchanged, darkening only occurred from below to a height of 12 cm.

[0081] From this result, it could be concluded that the bottom darkening was caused by rising water and the upper darkening was caused by the impregnation cream applied on top.

[0082] To verify the dark colorings, the two vertical side walls were broken out of the hollow block using a hammer and chisel. Water droplets were applied to the fractured surfaces with a pipette.

[0083] It was found that water droplets pipetted onto the bottom dark coloring were immediately absorbed and that, in contrast, water droplets pipetted onto the upper dark coloring formed water beads.

[0084] From these results, it can be concluded that the impregnation creams penetrate into the concrete body causing a water repellent effect.