Process and additive to improve adhesion of building compositions to substrates

Abstract

The present invention relates to the use of an additive as well as a process to improve the adhesion of a mortar to a building substrate, wherein the mortar is mixed with said additive and is applied to a building substrate selected from the group of polystyrene-containing substrates, polyolefin-containing substrates or polyvinyl chloride-containing substrates, the additive containing (i) a plasticizer that is liquid at 50 C. or lower, has a boiling point of 100 C. or higher, and that has a solubility parameter 25 C. between 22.5 MPa.sup.1/2 and MPa.sup.1/2; (ii) optionally, a filler that has a BET surface area of at least 40 m.sup.2/g; (iii) optionally, a biopolymer, (iv) optionally, a protective colloid; and (v) optionally, a water-insoluble film-forming (co)polymer based on ethylenically unsaturated monomers. The invention also covers an additive and a kit of parts suitable for use in the above process.

Claims

1. Process to adhere a mortar to a building substrate, the process comprising the steps of (A) mixing the mortar with at least one additive, (B) applying the mortar-additive mixture to a building substrate selected from the group consisting of polystyrene-containing substrates, polyolefin-containing substrates or polyvinyl chloride-containing substrates, and (C) allowing the mortar-additive mixture to dry, the additive comprising (i) a plasticizer that is liquid at 50 C. or lower, has a boiling point of 100 C. or higher, is capable of dissolving 1 wt % of the building substrate, and that has a solubility parameter at 25 C. between 22.5 MPa.sup.1/2 and 11 MPa.sup.1/2, the plasticizer being selected from esters, (ii) optionally, an inorganic filler that has a BET surface area of at least 40 m.sup.2/g; (iii) a polysaccharide selected from cold water-soluble polysaccharides, polysaccharide ethers, and synthetic anionic, nonionic and cationic heteropolysaccharides, the polysaccharide optionally being chemically modified with a substituent selected from the group consisting of carboxymethyl, carboxyethyl, hydroxyethyl, hydroxypropyl, methyl, ethyl, propyl, sulfate, phosphate and long chain alkyl groups; and/or (iv) a stabilizer selected from protective colloids; and wherein the additive is in the form of a liquid dispersion or powder obtained by mixing the plasticizer (i) with the polysaccharide (iii) and/or the stabilizer (iv) in pasty, swollen or dissolved form, optionally followed by drying said liquid dispersion, whereby the plasticizer (i) is not added to an aqueous dispersion containing a water-insoluble film-forming (co)polymer based on ethylenically unsaturated monomers, and wherein the additive is used in an amount of 0.005-5 percent by weight, based on the dry weight of the mortar, including the additive.

2. Process of claim 1, wherein the mortar is a dry mortar or contains a dry mortar component, the additive is added as a powder to the dry mortar or the dry mortar component, and the mortar is mixed with water and optional further liquid components prior to its application.

3. Process of claim 1, wherein the polysaccharide (iii) is used and wherein said polysaccharide (iii) is selected from the group consisting of cellulose ether, starch ether, guar ether, dextrine, alginate, xanthan gum, welan gum, and diutan gum.

4. Process of claim 3, wherein the stabilizer (iv) is used and wherein said stabilizer (iv) is a protective colloid and selected from the group consisting of fully or partially saponified polyvinyl alcohols and derivatives thereof, polyvinyl pyrrolidone, polyvinyl acetal, melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, polymerizates of propylene oxide and/or ethylene oxide, including copolymerizates and block copolymerizates thereof, styrene-maleic acid and vinyl ether-maleic acid copolymerizates.

5. Process of claim 3, wherein a filler (ii) is used and wherein said filler (ii) is an inorganic material selected from the group consisting of latent hydraulic binders and pozzolanic materials.

6. Process of claim 3, wherein the amount of plasticizer (i) based on the total solids content in the mortar is between 0.01 and 2 wt %.

7. Process of claim 3, wherein the mortar contains one or more mineral binders selected from the group of a) an hydraulically setting binder, b) a latent hydraulic binder which reacts hydraulically in combination with a calcium source and c) a non-hydraulic binder which reacts under the influences of air and water.

8. Process of claim 1, wherein the stabilizer (iv) is used and wherein said stabilizer (iv) is a protective colloid and selected from the group consisting of fully or partially saponified polyvinyl alcohols and derivatives thereof, polyvinyl pyrrolidone, polyvinyl acetal, melamine formaldehyde sulfonates, naphthalene formaldehyde sulfonates, polymerizates of propylene oxide and/or ethylene oxide, including copolymerizates and block copolymerizates thereof, styrene-maleic acid and vinyl ether-maleic acid copolymerizates.

9. Process of claim 8, wherein a filler (ii) is used and wherein said filler (ii) is an inorganic material selected from the group consisting of latent hydraulic binders and pozzolanic materials.

10. Process of claim 8, wherein the amount of plasticizer (i) based on the total solids content in the mortar is between 0.01 and 2 wt %.

11. Process of claim 8, wherein the mortar contains one or more mineral binders selected from the group of a) an hydraulically setting binder, b) a latent hydraulic binder which reacts hydraulically in combination with a calcium source and c) a non-hydraulic binder which reacts under the influences of air and water.

12. Process of claim 1, wherein a filler (ii) is used and wherein said filler (ii) is an inorganic material selected from the group consisting of latent hydraulic binders and pozzolanic materials.

13. Process of claim 12, wherein the amount of plasticizer (i) based on the total solids content in the mortar is between 0.01 and 2 wt %.

14. Process of claim 12, wherein the mortar contains one or more mineral binders selected from the group of a) an hydraulically setting binder, b) a latent hydraulic binder which reacts hydraulically in combination with a calcium source and c) a non-hydraulic binder which reacts under the influences of air and water.

15. Process of claim 1, wherein the amount of plasticizer (i) based on the total solids content in the mortar is between 0.01 and 2 wt %.

16. Process of claim 15, wherein the mortar contains one or more mineral binders selected from the group of a) an hydraulically setting binder, b) a latent hydraulic binder which reacts hydraulically in combination with a calcium source and c) a non-hydraulic binder which reacts under the influences of air and water.

17. Process of claim 1, wherein the mortar contains one or more mineral binders selected from the group of a) an hydraulically setting binder, b) a latent hydraulic binder which reacts hydraulically in combination with a calcium source and c) a non-hydraulic binder which reacts under the influences of air and water.

18. Process of claim 1, wherein the polysaccharide when present is a cellulose ether.

19. Process of claim 1, wherein the stabilizer when present is a protective colloid.

Description

EXAMPLES

(1) The invention is further elucidated with reference to the following examples. Unless indicated otherwise, the tests are carried out at a temperature of 23 C. and a relative humidity of 50%.

Example 1: Adsorption of Plasticizer on a Filler (50:50 Ratio)

(2) 20.0 g of Sipernat 22 (ex-Evonik Industries; a chemically obtained silicon dioxide having a BET surface of 190 g/m.sup.2, an average particle size of 100 m, measured following ISO 8130-1, and an average primary particle size of 15 nm were placed into a 300 ml plastic beaker. The same amount of the plasticizers, as indicated in Tables 1 and 2, was slowly added over a period of 2 minutes to the Sipernat 22, while continuously stirring using a 60 mm propeller stirrer with an increasing rate from low to 1,000 rpm. The resulting mixture was further mixed for another 20 minutes to result in a homogeneous, white, dry, and free-flowing powder. The plasticizers were all properly adsorbed and showed no signs of wetting when being put between fingers.

(3) The obtained powder can be easily mixed either directly with the other mortar components and/or with other solid mortar additives such as e.g. water-redispersible powders, cellulose ethers, cellulose fibres, defoamers, superplasticizers, hydrophobic agents, shrinkage reducing agents and/or additives to reduce efflorescence.

(4) It is noted that the same procedure can be followed using other fillers.

Example 2: Adsorption of Plasticizer on a Filler (60:40 Ratio)

(5) The procedure of Example 1 was repeated with the modification that a total of 30.0 g of plasticizer or of a mixture of plasticizers were added to 20.0 g of Sipernat 22. Again, the plasticizers were all properly adsorbed and showed no signs of wetting when being put between fingers.

Example 3: Preparation of Powder 1 (Mixture of Plasticizer and Protective Colloid as Stabilizer)

(6) To 100 g of a 20% aqueous polyvinyl alcohol solution with a degree of hydrolysis of 88 mol. % and a Hppler viscosity as 4% solution of 4 mPas in a 500 ml glass vessel with a propeller stirrer with a stirring speed of 1,000 rpm, were added slowly at room temperature 20.0 g of 2,2-ethylene dioxydiethylbis(2-ethylhexanoate) (OXFILM 351), while the plasticizer was emulsified completely. The obtained emulsion was subsequently dried by means of conventional spray drying at an inlet temperature of 125 C. to a white, free flowing, and readily water-redispersible powder in good yield, in which process no significant fouling occurred in the spraying tower. 100 parts by weight of the resultant powder were mixed with 13.6 parts by weight of a 83.3:16.7 mixture of commercially available calcium/magnesium carbonate and fumed silica.

Example 4: Preparation of a Dry Mortar Master Batch and Mortar Premix

(7) Prepared were 5 kg of a cement-based dry mortar master batch consisting of 340 parts by weight of a commercially available Portland cement CEM I 42.5, 598 parts by weight of a quartz sand (0.1-0.6 mm), 30 parts by weight of a commercially available hydrated lime, and 2 parts by weight of a commercially available cellulose ether (methylhydroxyethyl cellulose), in which process the components were mixed in a 10 l vessel with a FESTO stirrer until a homogeneous dry mortar master batch was obtained.

(8) For each experiment, samples of the dry mortar master batch were, where applicable, dry mixed with the plasticizer adsorbed on the filler and the water-redispersible powder, respectively. The respective amounts are indicated in Tables 1 and 2. 300 g of the obtained dry mixtures were added slowly to water while stirring. The amount of water used is indicated in Tables 1 and 2. This mixture was stirred for one minute with a 60 mm propeller stirrer with a speed of 800 rpm. After a maturing time of 3 minutes the mortar was again stirred by hand for 15 seconds before it was applied.

Example 5: Determination of the Adhesive Strengths on Expanded Polystyrene, Following ETAG 004 (Guideline for European Technical Approval of External Thermal Insulation Composite Systems with Rendering, European Organisation for Technical Approvals)

(9) Using a spacer, the mortar samples from Example 4 were applied with a thickness of 3 mm onto expanded polystyrene (EPS) blocks having the dimensions 500 mm100 mm60 mm and a density of 20 kg/m.sup.3. The specimens were stored at 23 C. and 50% relative humidity for 7 days (dry storage). Another set of specimens after the same dry storage period was immersed in water for 1 day. One day before the end of the dry storage period, 5 circles were drilled 5 mm deep into the EPS, using a crown driller with an inside diameter of 50 mm. Afterwards, metal plates with a 50 mm outer diameter were glued onto the cut mortar circles. The adhesive strengths and pull-out were determined in accordance with ETAG 004 by vertically pulling up the metal plate with the mortar specimen glued to it. The obtained data were averaged over the number of measured samples. The percentages of the pull-out were assessed visually. The measured adhesive strengths in N/mm.sup.2 are of less relevance, since they indicate the cohesion of the substrate at a 100% pull-out. At 0% pull-out, the values are so low that the adhesion of the mortar to the substrate is negligible.

(10) TABLE-US-00001 TABLE 1 Adhesion strengths, pull-out, and hydrophobicity of various mortar samples on EPS. Exp. No. 1-a 1-b 1-c (Ref) (Ref) (Ref) 1-d 1-e 1-f MEDA.sup.a) 0 0 0 0.5 0.25 0.1 DINP.sup.b) 0 0 0 0 0 0.4 S-22.sup.c) 0 0 0 0.5 0.25 0.5 RPP-1.sup.d) 0 0 0 0 0.5 0.5 RPP-2.sup.e) 0 1.5 3.0 0 0 0 H2O.sup.f) [%] 22 21 22 21 21 22 dry.sup.g) [%] 0 5 90 90 95 100 dry.sup.h) 0.05 0.11 0.16 0.14 0.13 0.15 N/mm.sup.2] wet.sup.i) [%] 0 5 50 85 85 100 wet.sup.j) 0.07 0.08 0.12 0.13 0.13 0.14 [N/mm.sup.2] Hydroph.sup.k) 35 50 50 >120.sup.l) >120.sup.l) >120.sup.l) [min] .sup.a)MEDA stands for methyl ester of dodecanoic acid (SigmaAldrich), which is a liquid at room temperature, having a boiling point of 261-262 C. and a solubility parameter of 16.0 MPa.sup.1/2. In experiments 1-d to 1-f, it was adsorbed on Sipernat 22 prior to being added to the mortar mixture. 5.0 g MEDA dissolve 0.05 g of the substrate used (EPS) at 23 C. within 1 minute. .sup.b)DINP stands for diisononyl phthalate (SigmaAldrich), which is a liquid at room temperature, having a boiling point of 270 to 280 C. and a solubility parameter of 18.1 MPa.sup.1/2. In experiment 1-f, it was adsorbed together with MEDA on Sipernat 22 prior to being added to the mortar mixture. 5.0 g DINP dissolve 0.05 g of the substrate used (EPS) at 23 C. within 3 days. .sup.c)S-22 stands for Sipernat 22 (Evonik). .sup.d)As water-redispersible polymer powder was added RPP-1, a polyvinyl alcohol-stabilized, ethylene-vinyl acetate copolymer with a glass transition temperature T.sub.g of 42 C. (Elotex MP2060). .sup.e)As water redispersible polymer powder was added RPP-2, a polyvinyl alcohol-stabilized, ethylene-vinyl acetate copolymer with a glass transition temperature T.sub.g of 4 C. (Elotex FX2320). .sup.f)Amount of added water to make up the mortar, based on 100 g dry mortar, including the mentioned additives. .sup.g)Pull-out after dry storage; 100% refers to 100% pull-out (only cohesion failure within the EPS) and 0% refers to no EPS pull-out, but just adhesion failure between the EPS-mortar interface. .sup.h)Measured adhesion/cohesion strength of specimen after dry storage. .sup.i)Pull-out after wet storage. .sup.j)Measured adhesion/cohesion strength of specimen after wet storage. .sup.k)The hydrophobicity was determined by dropping 0.5 ml of water onto the mortar surface and measuring the time until the water drop was fully absorbed. .sup.l)The water drop was still visible on the mortar surface after 2 hours.

(11) The results from Table 1 clearly show that a mortar without any additive (Exp. 1-a) does not properly adhere on EPS, since the pull-out is 0% after both dry and wet storage. When a state-of-the-art redispersible powder RPP-2 is added to the mortar, which is particular suitable for improving the adhesion to EPS, even amounts of e.g. 3 wt. % (Exp. 1-c) do not lead to a pull-out of 100%. However, when use is made of a small amount of a suitable plasticizer (e.g. only 0.25 wt. % in Exp. 1-e) or mixture of plasticizers (Exp. 1-f) which can be adsorbed on an inorganic carrier, good to excellent pull-out is achieved after dry and wet storage (Exp. 1-d to 1-f).

(12) While RPP-1 does not contribute to mortar adhesion to EPS (see e.g. Exp. 2-b), it does increase the cohesion of the mortar as well as contributing to the adhesion of the mortar to e.g. concrete, which is a typical substrate the EPS boards are adhered to when insulating buildings. Thus, it is easily possible to optimize mortar adhesion to EPS by adding a small amount of a suitable plasticizer. In addition to this, it is possible to choose independently thereof redispersible powders which are most suitable to provide other sought after properties, such as improved mortar cohesion and improved adhesion to inorganic substrates such as concrete, without compromising on other properties such as adhesion to difficult-to-bond substrates such as polystyrene-, polyolefin-, and polyvinyl chloride-containing substrates.

(13) TABLE-US-00002 TABLE 2 Adhesion strengths, pull-out and hydrophobicity of various mortar samples on EPS. Exp. No. 2-a 2-b (Ref) (Ref) 2-c 2-d 2-e 2-f DBP.sup.a) 0 0 .sup.0.75.sup.j) 0.25 0.083 0.375 S-22.sup.b) 0 0 0 0.25 0.083 0.375 RPP-1.sup.c) 0 1.0 0 0 0.083 0.75 H2O.sup.d) [%] 22 22 21 21 21 21 dry.sup.e) [%] 0 0 100 100 55 100 dry.sup.f) [N/mm.sup.2] 0.05 0.07 0.15 0.15 0.13 0.13 wet.sup.g) [%] 0 0 100 100 70 100 wet.sup.h) [N/mm.sup.2] 0.07 0.05 0.13 0.15 0.13 0.14 Hydroph.sup.i) [min] 35 40 N/A.sup.k) 30 N/A.sup.k) 60 .sup.a)DBP stands for dibutyl phthalate (SigmaAldrich), which is a liquid at room temperature, having a boiling point of 340 C. and a Hansen solubility parameter of 20.3 MPa.sup.1/2. In experiments 2-d to 2-f, it was adsorbed on Sipernat 22 prior to being added to the mortar mixture. 5.0 g DBP dissolve 0.05 g of the substrate used (EPS) at 23 C. within 15 minutes. .sup.b)S-22 stands for Sipernat 22 (Evonik). .sup.c)As water-redispersible polymer powder was added RPP-1, a polyvinyl alcohol-stabilized, ethylene-vinyl acetate copolymer with a glass transition temperature T.sub.g of 42 C. (Elotex MP2060). .sup.d)Amount of added water to make up the mortar, based on 100 g dry mortar, including the mentioned additives. .sup.e)Pull-out after dry storage; 100% refers to 100% pull-out (only cohesion failure within the EPS) and 0% refers to no EPS pull-out, but just adhesion failure between the EPS-mortar interface. .sup.f)Measured adhesion/cohesion strength of specimen after dry storage. .sup.g)Pull-out after wet storage. .sup.h)Measured adhesion/cohesion strength of specimen after wet storage. .sup.i)The hydrophobicity was determined by dropping 0.5 ml of water onto the mortar surface and measuring the time until the water drop was fully absorbed. .sup.j)The DBP was added as a liquid to the mortar batch prior to water addition. .sup.k)No data are available.

(14) The results from Table 2 clearly show that a mortar without any additive (Exp. 2-a) and a mortar with 1 wt. % of a water-redispersible powder only (Exp. 2-b) do not really adhere on expanded polystyrene, since the pull-out is 0% after both dry and wet storage. However, when even a small amount of plasticizer is added, the adhesion increases significantly. For example, 0.75 wt. % of DBP (Exp. 2-c), which was added as liquid to the mortar, leads to 100% pull-out after dry and wet storage. The same results can also be achieved with significantly lower amounts. The same good adhesion characteristics can be found when DBP is adsorbed on a carrier, even at significantly lower added amounts. Thus, it was highly surprising to see that even a very small amount of 0.083 wt. % of DBP still gives a pull-out of 55% after dry and of 70% after wet storage. This result is even more surprising since the DBP, being adsorbed on a carrier, is insoluble in water.

(15) Besides achieving excellent mortar adhesion to EPS with very small amounts of various types of plasticizers, it is also possible to adjust the mortar hydrophobicity according to specific needs. Thus when e.g. using a fatty acid ester such as a methyl ester of dodecanoic acid (Exp. 1-d to 1-f), a hydrophobic mortar surface is obtained, leading to water-repelling characteristics. However, when this feature is not sought, another plasticizer, e.g. DBP, can be used (Exp. 2-c to 2-f).

(16) TABLE-US-00003 TABLE 3 Adhesion strengths and pull-out of various mortar samples on EPS. Exp. No 3-a 3-b 3-c 3-d 3-e 3-f 3-g DINCH.sup.a) 0 0 0.15 0.10 0.0625 0 0 Oxfilm 0 0 0 0.02 0 0 0 351.sup.b) RME.sup.c) 0 0 0 0 0.0125 0 0 Mesa- 0.15 0.15 0 0 0 0 0 moll.sup.d) S-22.sup.e) 0.15 0.15 0.15 0.08 0.05 0 0 Powder 1.sup.f) 0 0 0 0 0 0.1 0.2 RPP-1.sup.e) 0 1.2 1.2 0.8 1.125 0 0 RPP-2.sup.e) 1.2 0 0 0 0 0 0 H.sub.2O.sup.e) [%] 21 21 21 21 21 21 21 dry.sup.e) [%] 80 70 100 100 100 95 100 dry.sup.e) 0.12 0.11 0.12 0.12 0.11 0.12 0.13 [N/mm.sup.2] wet.sup.e) [%] 95 65 100 100 95 75 100 wet.sup.e) 0.12 0.11 0.11 0.10 0.11 0.10 0.11 [N/mm.sup.2] .sup.a)DINCH stands for Diisononyl-1,2-cyclohexanedicarboxylate (HEXAMOLL DINCH from BASF), which is a liquid at room temperature, having a boiling point of 240-250 C. and a solubility parameter at 25 C. of 17.0 MPa.sup.1/2. 5.0 g DINCH dissolve 0.05 g of the substrate used (EPS) at 23 C. within 3 days. .sup.b)Oxfilm 351 stands for 2,2-Ethylenedioxydiethylbis(2-ethylhexanoate) (Oxea Chemicals), which is a liquid at room temperature, having a boiling point of 351 C. and a solubility parameter at 25 C. of between 22.5 MPa.sup.1/2and 11 MPa.sup.1/2. 5.0 g Oxfilm 351 dissolve 0.05 g of the substrate used (EPS) at 23 C. within 15 minutes. .sup.c)RME stands for Rape Oil Methyl ester (Flamol Mineralol; Bern, CH), which is a liquid at room temperature, having a boiling point of above 200 C. and a solubility parameter at 25 C. of about 17 MPa.sup.1/2. 5.0 g RME dissolve 0.05 g of the substrate used (EPS) at 23 C. within 5 minutes. .sup.d)Mesamoll stands for alkyl sulfonic phenyl ester (Lanxess), which is a liquid at room temperature, having a boiling point of about 200 C. and a solubility parameter at 25 C. of about 20 MPa.sup.1/2. 5.0 g Mesamoll dissolve 0.05 g of the substrate used (EPS) at 23 C. within 3 days. .sup.e)See Table 1 for explanation. .sup.f)Powder 1 is made according to Example 3.

(17) In Exp. No. 3-a to 3-c powders according to Example 1 are used. They indicate that the type of RPP, i.e. component (v), does not have a real impact on the adhesion on the substrate. However, adding a plasticizer makes a distinct difference.

(18) Powders according to Example 2 are used in Exp. No. 3-d and 3-e and powders according to Example 3 are used in Exp. No. 3-f and 3-g. They further demonstrate the powerful effect of the present invention. Thus, only 0.075 wt. % of a plasticizer mixture (e.g. Exp. No. 3-e) adsorbed on an even smaller amount of an inorganic carrier provides excellent adhesion to the substrate to give about full cohesion failure inside the substrate. Or, adding to the mortar only 0.2 wt. % of Powder 1 according to Example 3, representing only 0.086 wt % of plasticizer in the mortar (e.g. Exp. No. 3-g), provides a 100% pull-out after dry and wet storage, respectively.