WO2016011955A1

WO2016011955A1 - Additive for minerally setting aqueous mortar compositions

Info

Publication number: WO2016011955A1
Application number: PCT/CN2015/084879
Authority: WO
Inventors: Richard Zhang; Manfred Selig; Thomas Bastelberger; Saulat Aijaz KHAN; Ginger MERRITT; Tanja KOEPPING
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2014-07-23
Filing date: 2015-07-23
Publication date: 2016-01-28
Anticipated expiration: 2017-01-23
Also published as: BR112017001425A2; CN105330195A; MX2017000989A

Abstract

An additive for minerally setting aqueous mortar compositions, wherein the additive consists essentially of a) a water-redispersible poly-mer powder, and b) a cellulose-ether powder, and use of the additive in the preparation of a minerally setting aqueous mortar composition, and the minerally setting mortar composition obtained with the additive.

Description

Additive for minerally setting aqueous mortar compositions

The invention relates to an additive for minerally setting aqueous mortar compo-sitions, the use of the additive in the preparation of a minerally setting aqueous mortar composition, and the minerally setting mortar composition obtained with the additive.

Throughout the first third of the 20^th century any kind of minerally setting aque-ous mortar compositions were mixed from several raw materials immediately for use on the construction site. In steel troughs or motorized mixing drums first the dry compounds such as mineral binder, for example, cement, and filler for exam-ple sand, and further additives, for example thickener, were mixed and then brought to the desired consistency by the addition of water.

Since then, the quality requirements for building materials have drastically in-creased and today industrially produced dry mortars are used for the preparation of building materials. Dry mortar is the term for mortars whose dry components were mixed in the factory of a building materials manufacturer based on fixed instructions.

The basic ingredients of such prefabricated dry mortars are mineral binders such as cement, gypsum or lime, and fillers such as sand, thickeners for the adjustment of rheology, accelerators and retarders for adjusting workability, and water-redispersible polymer powders for the improvement of mechanical properties of the hardened mortar layer.

For improvement of such dry mortar compositions, further additives are incorpo-rated into the dry mortar composition: WO 03/106369 A1 describes an additive for improving rheological flow behavior and which comprises a water-soluble ether of cellulose and a polycarboxylate. EP 2297060 B1 discloses a rheology influencing additive which contains a combination of dispersing agents and stabi-lizers. WO 2011/073224 A1 describes the use of an additive, containing a plasti-cizer, to improve the adhesion of a mortar to a building substrate. WO 2011/098412 A1 discloses the hydrophobization of mortars with a rosin additive.

Such dry mortars are delivered in bags or loose (in silos) to the construction site. Before processing the dry mortar is mixed without further ingredients with only a defined amount of water. The advantages of dry-mortars are the factory backed product quality, and the high storage stability as no freezable liquid components are included.

The precondition for obtaining all the above-mentioned advantages of the appli-cation of dry mortars, is a highly developed infrastructure, which ensures a reli-able transportation of the dry mortars from the factory to the building site, and which ensures a regionwide distribution of such products via hardware stores and specialized retailers. In regions with a lower developed infrastructure, cement, sand and water (the basic ingredients for mortars) are immediately available in local stores, but not dry mortars. In consequence, building materials which fulfill the quality standards obtainable with dry mortar compositions are not available.

Taking this background into account, the object was to provide means which en-able the preparation of high quality building materials, starting with universally available basic materials like cement, sand and water, and achieving mortars which show a workability and a mechanical strength of the hardened mortar, which is similar to those obtained with factory made dry mortars.

Surprisingly, it was found that the object can be attained by means of an additive for minerally setting aqueous mortar compositions, wherein the additive consists essentially of

a) a water-redispersible polymer powder, and

b) a cellulose-ether powder.

Water-redispersible polymer powders are generally obtained by drying the corre-sponding aqueous polymer dispersions in the presence of a drying aid (generally a protective colloid) and of an antiblocking agent. Because of the protective col-loid content, irreversible adhesion of the polymer particles is firstly prevented in the course of the drying operation, since the polymer particles are encased by the water-soluble protective colloid particles. Secondly, this protective colloid matrix, which redissolves when the polymer powder is dispersed in water, has the effect that the polymer particles are again present in the aqueous redispersion with the particle size of the starting dispersion (TIZ-Fachberichte, 1985, Vol. 109 (9) , 698) .

The water-redispersible polymer powders are based in general on polymers of one or more ethylenically unsaturated monomers. Preferred ethylenically unsatu-rated monomers are selected from the group encompassing vinyl esters, (meth) acrylic esters, vinylaromatics, olefins, 1, 3-dienes, and vinyl halides, and optionally further monomers copolymerizable therewith.

Suitable vinyl esters are, for example, those of carboxylic acids having 1 to 15 C atoms. Suitable monomers from the group of acrylic esters or methacrylic esters are, for example, esters of unbranched or branched alcohols having 1 to 15 C at-oms. Preferred vinylaromatics are styrene, methylstyrene, and vinyltoluene. A preferred vinyl halide is vinyl chloride. The preferred olefins are ethylene and propylene, and the preferred dienes are 1, 3-butadiene and isoprene.

Optionally it is also possible for 0, 1 to 10％by weight of auxiliary monomers to be copolymerized, based on the total weight of the monomer mixture. Preference is given to using 0, 1 to 5％by weight of auxiliary monomers. Examples of auxil-iary monomers are ethylenically unsaturated monocarboxylic and dicarboxylic acids, ethylenically unsaturated carboxamides and carbonitriles, and also maleic anhydride, ethylenically unsaturated sulfonic acids and their salts. Other exam-ples for auxiliary monomers are pre-crosslinking comonomers such as poly-ethylenically unsaturated comonomers, or post-crosslinking comonomers, exam-ples being N-methylolacrylamide (NMA) , N-methylolmethacrylamide. Also suit-able are epoxide-functional comonomers such as glycidyl methacrylate and sili-con-functional comonomers, such methacryloyloxypropyltrialkoxysilanes, vinyl-trialkoxysilanes

Examples of suitable homo-and copolymers are vinyl acetate homopolymers, copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with eth-ylene and one or more further vinyl esters, copolymers of vinyl acetate with one or more further vinyl esters, copolymers of vinyl acetate with ethylene and acrylic esters, copolymers of vinyl acetate with ethylene and vinyl chloride, co-polymers of vinyl chloride and ethylene and optionally one or more further vinyl esters, styrene-acrylic ester copolymers, styrene-1, 3-butadiene copolymers, where the polymers may each also contain the auxiliary monomers mentioned in the amounts mentioned, and the figures in％by weight add up to 100％by weight in each case.

Preference is given to vinyl acetate homopolymers； copolymers of vinyl acetate with 1 to 50％by weight of one or more further comonomers from the group of the vinyl esters having 1 to 12 carbon atoms in the carboxyl radical, such as vinyl propionate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having 5 to 12 carbon atoms, such as VeoVa9^R, VeoVa10^R； copolymers of vinyl acetate with 1 to 40％by weight of ethylene； copolymers of vinyl acetate with 1 to 40％by weight of ethylene and 1 to 50％by weight of one or more further comono-mers from the group of the vinyl esters having 1 to 12 carbon atoms in the car-boxyl radical, such as vinyl propionate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having 5 to 12 carbon atoms, such as VeoVa9^R, Ve-oVa10^R； copolymers of vinyl acetate, 1 to 40％by weight of ethylene and pref-erably 1 to 60％by weight of (meth) acrylic esters of unbranched or branched al-cohols having 1 to 15 carbon atoms, especially methyl methacrylate, methyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate； copolymers with 30 to 75％by weight of vinyl acetate, 1 to 30％by weight of vinyl laurate or vinyl esters of an alpha-branched carboxylic acid having 5 to 12 carbon atoms, and 1 to 30％by weight of (meth) acrylic esters of unbranched or branched alcohols having 1 to 15 carbon atoms, especially methyl methacrylate, methyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate, which may also contain 1 to 40％by weight of ethylene； copolymers with one or more vinyl esters having 1 to 12 carbon atoms in the car-boxyl radical, such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl esters of alpha-branched carboxylic acids having 5 to 12 carbon atoms, such as Ve-oVa9^R, VeoVa10^R, 1 to 40％by weight of ethylene and 1 to 60％by weight of vinyl chloride； where the polymers may each also contain the auxiliary mono-mers mentioned in the amounts mentioned, and the figures in％by weight add up to 100％by weight in each case.

The monomer selection and the selection of the weight fractions of the comono-mers are preferably made here so as to result in a glass transition temperature, Tg, of 50℃ to +50℃, more preferably –40℃ to +40℃, most preferably -20℃ to +30℃. The glass transition temperature Tg of the polymers can be determined in a known way by means of Differential Scanning Calorimetry (DSC) . The Tg may also be calculated approximately in advance using the Fox equation. According to Fox T. G., Bull. Am. Physics Soc. 1, 3, page 123 (1956) the following is the case: 1/Tg ＝ x1/Tg1 + x2/Tg2 +...+ xn/Tgn, where xn stands for the mass frac-tion (wt％/100) of the monomern, and Tgn is the glass transition temperature, in kelvins, of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2nd Edition, J. Wiley &Sons, New York (1975) .

The polymers are prepared generally in an aqueous medium and preferably by the emulsion or suspension polymerization process, as described for example in WO 2010/057888 A1. The polymers in that case are obtained in the form of aqueous dispersions. In the polymerization it is possible to use the customary protective colloids and/or emulsifiers, as described in WO 2010/057888 A1. As protective colloids preference is given to partially hydrolyzed or fully hydrolyzed polyvinyl alcohols, having a degree of hydrolysis of 80 to 100 mol-％, more par-ticularly to partially hydrolyzed polyvinyl alcohols having a degree of hydrolysis of 80 to 94 mol-％and a

viscosity, in 4％strength aqueous solution, of 1 to 30 mPas (

method at 20 ℃， DIN 53015) . The stated protective colloids can be obtained by methods known to the skilled person, and are added generally in an amount of in total 1 to 20％by weight, based on the total weight of the monomers, in the polymerization.

The polymers in the form of aqueous dispersions may be converted by spray-drying into corresponding powders that are redispersible in water, as described in WO 2010/057888 A1, for example. In that case it is usual to add a drying aid in a total amount of 3 to 30％by weight, based on the polymeric constituents of the dispersion. A preferred drying aid are the abovementioned polyvinyl alcohols. Additionally antiblocking agent maybe added during or after the drying step.

The water-redispersible polymer powders are also commercially available. For example Vinnapas^R dispersion powders of Wacker Chemie AG.

One or more cellulose ethers can be used. They are preferably selected from the group of alkyl cellulose ethers, hydroxyalkyl cellulose ethers, carboxyalkyl cellu- lose ethers, and of mixed ethers with at least two different substituents from the group of alkyl, hydroxyalkyl, carboxyalkyl with in each case alkyl groups with 1 to 10 carbon atoms. The alkyl groups are preferably methyl, ethyl and/or propyl groups and the hydroxyalkyl groups are preferably hydroxymethyl, hydroxyethyl and/or hydroxypropyl groups. The Brookfield viscosity of the cellulose ether measured at 20 rpm and as a 2％aqueous solution at 20℃ is in general 100 to 100000 mPas, preferably 1000 to 75000 mPas and in particularly preferred 5000 to 50000 mPas.

Particularly preferred cellulose ethers are methyl cellulose (MC) , ethyl cellulose (EC) , methyl hydroxyethyl cellulose (MHEC) , ethyl hydroxyethyl cellulose (EHEC) , methyl ethyl hydroxyethyl cellulose (MEHEC) , hydroxyethyl cellulose (HEC) , hydroxypropyl cellulose (HPC) , methyl hydroxypropyl cellulose (MHPC) , hydroxypropyl methyl cellulose (HPMC) , hydroxyethyl methyl cellu-lose (HEMC) , carboxymethyl cellulose (CMC) .

The cellulose ethers are commercially available. For example Berocoll^R of AkzoNobel NV, Walocel^R of Wolff Cellulosics GmbH &Co. KG, Methocel^R or Cellosize^R of Dow Chemical Company, Tylose^R of SE Tylose GmbH&Co. KG, Culminal^R or Natrosol^R of Ashland Inc..

Preferably the additive consists essentially from 50 to 95％by weight of one or more water-redispersible polymer powders a) , and from 5 to 50％by weight of one or more cellulose-ether powder b) , based on the dry weight of the additive composition. More preferred the additive consists essentially from 50 to 75％by weight of one or more water-redispersible polymer powders a) , and from 25 to 50 ％by weight of one or more cellulose-ether powder b) , based on the dry weight of the additive composition. The additive may also include further ingredients in minor amounts from 1 to 10％by weight, based on the dry weight of the additive composition in each case, and the figures in％by weight add up to 100％by weight in each case. Examples for further ingredients are fillers such as sand, quartz powder and/or calcium carbonate, and/or setting retarders such as saccha-rose, and/or setting accelerators such as calcium formate, and/or defoamer, and/or water reppellants such as fatty acid esters, and/or stabilizers such as poly-vinyl alcohol.

For the preparation of the additive the components a) and b) and optionally fur-ther ingredients are mixed with one another in powder form using commercially available mixers. If one of the further ingredients is in liquid form the compo-nents a) and b) are mixed as powders with the further ingredient in liquid form. Liquid ingredients can also be applied absorbed on a solid, powdery carrier mate-rial.

The additive according to the present invention makes it possible to obtain high quality aqueous mortars by starting with universally available basic materials such as cement, sand and water. To achieve this goal even in the case of small job-sites, and additionally for simplifying dosing of the additive, the additive is packed in relatively small portions. Preferably the additive is distributed in por-tions of 50 g to 10 kg, more preferred in portions of 50 g to 1 kg. In smaller packaging size the portions of the additive maybe packed in sachets. For bigger packaging size the portions of the additive maybe packed in buckets.

For the preparation of the minerally setting aqueous mortar composition modified with the additive according to the invention, in a first step the additive is admixed with the mineral binder and the filler in a dry mixing step. In the second step the additive-containing dry mix is admixed with water for obtaining the minerally setting aqueous mortar composition.

Preferably from 1 to 10％by weight, more preferred from 1 to 5％by weight of the additive, in each case based on the dry weight of the mineral binder, is added to the mortar composition.

As preferred mineral binders, which are universally available, can be used ce-ment, particularly Portland cement and/or calcium-aluminate cement, and/or gyp-sum, and/or lime, and/or puzzolanes such as volcanic slag and/or volcanic tuft and/or fly ash and/or blast-furnace slag.

As preferred filler materials, which are universally available, can be used for ex-ample sand, and/or chalks, and/or clay.

The minerally setting aqueous mortar composition modified with the additive comprises in general from 5 to 80 parts by weight of mineral binder, and from 20 to 95 parts by weight of filler, and water in an amount for reaching the desired consistency of the aqueous mortar. In the given framework the compositions of the aqueous mortar depends on the application of the mortar. For example, the minerally setting aqueous mortar composition modified with the additive can be formulated as plaster, or as flow bed mortar, or as repair mortar, or as tile grout, or as floor screed.

Examples:

A tile adhesive obtained with a premixed dry mortar mixture (comparison exam-ple 1) was compared with a tile adhesive obtained by mixing cement, sand, the inventive additive and water (example 2)

Comparison example 1:

Dry mortar mixture with

300,0g cement (OPC CEM 42.5, MilkeZement GmbH&Co. KG)

686,5 g quartzsand (Quarzsand F31/F36, 1:1, Quarzwerke GmbH)

3,5 g cellulose ether (TyloseMB3003P4, ShinEtsu SE)

5,0 g redispersible powder (polyvinyl-alcohol-stabilized vinyl acetate ethylene copolymer, Vinna pas 4023N of Wacker Chemie AG)

5,0 g Calciumformiat (Fluka GmbH)

The dry mortar formulation was mixed with 265 g water to form a tile adhesive.

Example 2:

300.0 g cement (OPC CEM 42.5, MilkeZement GmbH&Co. KG)

686,5 g quartz sand (Quarzsand F31/F36, 1:1, Quarzwerke GmbH)

8,5 g of additive

The additive was obtained by mixing 3,5 g cellulose ether (Tylose MB3003P4) and 5,0 g redispersible powder (Vinnapas 4023N) .

The cement, the sand and the additive were mixed, and 265 g water was admixed to form a tile adhesive.

Determination of the tensile bond strengths:

For testing, the tile adhesive compositions of comparison example 1 and example 2 were each applied to concrete paving slabs using a 5 mm toothed trowel. Then 5 tiles (5 x 5 cm) were laid on each slab and weighted down for 30 seconds using a 2 kg weight.

The tensile bond strengths were tested in each case after the following storage conditions:

Storage under standard conditions (SC) :

28 days at 23℃ and 50％humidity.

Wet storage (WS) :

7 days of storage under standard conditions followed by 21 days of storage at 20℃ in water.

The tensile bond strengths were determined in accordance with DIN EN 1348, in each case following the abovementioned storage, using a pulloff device from Herion, with a load increase rate of 250 N/s. The measurements, in N/mm², rep-resent mean values of 5 measurements.

Example	Tensile Strength (SC)	Tensile Strength (WS)
Example	Tensile Strength (SC)	Tensile Strength (WS)
Comp. Example 1	1,17 N/mm²	0,97 N/mm²
Comp. Example 1	1,17 N/mm²	0,97 N/mm²	Example 2	1,16 N/mm²	0,93 N/mm²

Claims

Additive for minerally setting aqueous mortar compositions, wherein the additive consists essentially of

a) a water-redispersible polymer powder, and

b) a cellulose-ether powder.
Additive according to claim 1, wherein the water-redispersible polymer powder comprises a polymer of one or more ethylenically unsaturated monomers selected from the group comprising vinyl esters, (meth) acrylic esters, vinylaromatics, olefins, 1, 3-dienes, and vinyl halides, and optionally further monomers copolymerizable therewith.
Additive according to claim 1, wherein the water-redispersible polymer powder comprises a polymer selected from the group comprising vinyl acetate homopolymers, copolymers of vinyl acetate with ethylene, co-polymers of vinyl acetate with ethylene and one or more further vinyl es-ters, copolymers of vinyl acetate with one or more further vinyl esters, co-polymers of vinyl acetate with ethylene and acrylic esters, copolymers of vinyl acetate with ethylene and vinyl chloride, copolymers of vinyl chlo-ride and ethylene and optionally one or more further vinyl esters, styrene-acrylic ester copolymers, styrene-1, 3-butadiene copolymers, in each case optionally further monomers copolymerized therewith.
Additive according to one of the claims 1 to 3, wherein the cellulose ether powder is selected from the group of alkyl cellulose ethers, hydroxyalkyl cellulose ethers, carboxyalkyl cellulose ethers, and of mixed ethers with at least two different substituents from the group of alkyl, hydroxyalkyl, car-boxyalkyl with in each case alkyl groups with 1 to 10 carbon atoms.
Additive according to one of the claims 1 to 3, wherein the cellulose ether powder is selected from the group of methyl cellulose (MC) , ethyl cellu-lose (EC) , methyl hydroxyethyl cellulose (MHEC) , ethyl hydroxyethyl cel-lulose (EHEC) , methyl ethyl hydroxyethyl cellulose (MEHEC) , hy-droxyethyl cellulose (HEC) , hydroxypropyl cellulose (HPC) , methyl hy- droxypropyl cellulose (MHPC) , hydroxypropyl methyl cellulose (HPMC) , hydroxyethyl methyl cellulose (HEMC) , carboxymethyl cellulose (CMC) .
Additive according to one of the claims 1 to 5, wherein

the additive consists essentially from 50 to 95 ％by weight of one or more water-redispersible polymer powders a) , and from 5 to 50 ％by weight of one or more cellulose-ether powder b) , based on the dry weight of the ad-ditive composition.
Additive according to one of the claims 1 to 6, wherein

the additive is distributed in portions of 50 g to 10 kg.
Use of the additive in the preparation of a minerally setting aqueous mortar composition comprising one or more mineral binders, and one or more fill-ers, wherein 0, 5 to 10 ％by weight, based on the dry weight of the mineral binder, of the additive according to one of the claims 1 to 7 is added to the mortar composition.
Minerally setting aqueous mortar composition modified with the additive according to one of the claims 1 to 7, comprising 5 to 80 parts by weight of mineral binder, and from 20 to 95 parts by weight of filler, and water in an amount for reaching the desired consistency of the aqueous mortar.