WO2010055038A1 - Compositions which set hydraulically at low temperatures - Google Patents

Abstract

The invention provides compositions which set hydraulically at low temperatures and comprise, as well as additives for lowering the freezing point of water, also homo- or copolymers of ethylenically unsaturated monomers which are used in the form of aqueous dispersions or water-redispersible powders thereof, characterized in that the homo- or copolymers have a minimum film formation temperature of 5°C.

Description

Hydraulically setting compounds at low temperatures

The present invention relates to hydraulically setting compositions at low temperatures and to the use of homopolymers or copolymers of ethylenically unsaturated monomers, in the form of their aqueous dispersions or powders redispersible in water, for producing such compositions.

Hydraulically setting compounds are systems with a hydraulic binder such as cement, gypsum or waterglass, optionally with fillers, and optionally further additives such as thickeners, which are mixed with water. To accelerate the setting of the mortar, cement accelerators can also be added to such systems, and homopolymers or copolymers of ethylenically unsaturated monomers, in the form of their aqueous dispersions or water-redispersible powders, are frequently used to improve the mechanical strength. The constituents of these mixtures, which in the case of water-redispersible powders may also be in the form of a dry mortar mixture, are then mixed with water to form the mortar.

Due to the proportion of water, the processing of the hydraulically setting mortar at low temperatures, that is, with increasing proximity to the freezing point of the water or below the freezing point of water, only limited possible. At temperatures <5 ° C, the hydration of the mortar is slowed down so that the mortar masses can freeze before the hydration is complete. Consequently, when the mortars are frozen at an early stage of hydration, the mechanical strength, hardness and water resistance of the solidified mortar masses are reduced in an intolerable manner. In addition, the mortars hardened at such low temperatures can cause damage such as cracking and flaking.

Particularly problematic is the setting at temperatures <5 ° C for hydraulically setting mortar compounds, which in rela ™ tively thin layers are applied. Examples of this are the application as a construction adhesive for tile bonding or the bonding of thermal insulation composite systems and the application as a reinforcing mortar in thermal insulation systems.

In the prior art, to improve the processability of hydraulically setting mortar compounds, at such low temperatures, additives for lowering the freezing point or additives for accelerating the cement bonding are recommended:

In U.S. Patents 4,054,462 and 4,482,379, calcium chloride is added to the cementitious mass to lower the freezing point. US Pat. No. 3,937,282 recommends the use of alkali metal chlorides to lower the freezing point of a cementitious mortar composition. In JP 2006-306646 A2, the use of hectorite, a Li-oxide-containing Sσhichtsili- cat, for accelerating the setting at low temperatures is recommended. From JP-2006-306647 A2 the use of lithium salts is known. U.S. Patent 4,375,987 describes the addition of antifreeze agents such as alcohols (methanol, ethanol) or glycols. U.S. Patent 4,054,461 recommends the addition of a combination of alkali metal nitrate and retarder to improve the low temperature processability of cementitious materials. In order to improve the low-temperature processability, EP 241554 B1 describes the cement to be mixed with a small-scale ice mass instead of water.

These measures do not lead especially in the tying place at temperatures <5 ⁰ C of hydraulically setting mortar compositions, which are applied in relatively thin layers to produce satisfactory results.

As a result thereof, according to the prior art just described, with additives for lowering the freezing point, modified mortar trays, after their solidification, insufficient adhesion or tend to cracking on entry of higher temperatures. DE 19528380 A1 discloses heterogeneous vinyl acetate-ethylene dispersions in which heterogeneous polymer particles having two different polymer phases, one ethylene-rich and one ethylene-poor, having two different glass transition temperatures TgI and Tg2 are present. These copolymers are described as highly flexible and low-temperature resistant binders in sealing slurries to -30 ⁰ C. The disadvantage here is the complex production process.

It was therefore an object to improve hydraulically setting mortar compounds so that, even with application of the mortar compound at temperatures <5 ° C and in thin layers of 0.5 mm to 50 mm, cured masses with good adhesion to the ground and without inclination result in cracking after temperature increase.

The invention relates to hydraulically setting compositions which, in addition to additives for lowering the freezing point of water, contain homo- or copolymers of ethylenically unsaturated monomers which are used in the form of their aqueous dispersions or water-redispersible powders, characterized in that the homopolymers or copolymers have a minimum heat-sink temperature of <5 ^° C.

Typical formulations for hydraulically setting compositions contain as hydraulic binder one or more of the group containing cement, in particular Portland, aluminate, trass, metallurgical, magnesia, phosphate or blast-furnace cement; as well as mixed cement, hydraulic lime and gypsum. Another constituent is one or more fillers from the group comprising quartz sand, gravel, carbonaceous fillers such as calcium carbonate, talc, light fillers, hollow spheres, pozzolanically reacting fillers such as fly ash, metakaolin, microsilica, cellulose fiber and gumshellis. The additives for lowering the freezing point of water are preferably under normal conditions (T = 20 ⁰ C, DIN 50014 20/65) in solid form. Suitable additives for lowering the freezing point of water are one or more compounds from the group of alkali metal salts and alkaline earth metal salts of inorganic or organic acids. The lithium, sodium, potassium, magnesium and calcium salts are preferred. Preferred inorganic counterions are carbonate, chloride, sulfate, nitrate and phosphate ion. Preferred organic counterions are carboxylate groups which are derived from carboxylic acids having 1 to 4 C atoms, such as formate, acetate, propionate and butyric ion. Particularly preferred are the calcium salts. Most preferred are the calcium salts of carboxylic acids having 1 to 4 C atoms, such as calcium formate, calcium acetate. Other suitable additives for lowering the freezing point of water are, for example, aluminum salts such as aluminates, aluminum hydroxide, aluminum nitrate, aluminum sulfate. Also suitable are alkali metal silicates or alkali metal hydroxides,

The performance properties of the hydraulically setting compositions can be improved by adding additives. Examples of these are thickeners, pigments, foam stabilizers, setting accelerators, water repellents, plasticizers, fly ash, disperse silica, flow agents, air pore agents for controlling the concrete density or pumping aids to improve pumpability.

Preference is given to the use of setting accelerators in the compositions which are hydraulically setting at low temperatures, which are generally different from the additives used to lower the freezing point of water. Suitable setting accelerators are known to the person skilled in the art: Examples of these are compounds from the group of alkali metal salts and alkaline earth metal salts of inorganic or organic acids, aluminum salts such as aluminum fluoride, aluminum sulfate or aluminum hydroxide. Further examples are alkanolamines such as triethanolamine or monoethanolamine, single or double NH ₂ nierte polyalkylene glycols with Ci to C ₆ alkylene group, which may be present in each case in the form of their salts.

Suitable monomers for the preparation of the homopolymers and copolymers are vinyl esters of unbranched or branched alkylcarboxylic acids having 1 to 15 C atoms, methacrylic acid esters and acrylic esters of alcohols having 1 to 15 C atoms, vinylaromatics, olefins, dienes or vinyl halides. The homopolymers and mixed polymers to be used according to the invention are in each case homogeneous polymers, that is to say polymers having a single glass transition temperature Tg.

Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of alpha-branched monocarboxylic acids having 9 to 13 C atoms, for example VeoVa9® or VeoValO® ( Trade name of the company Shell). Particularly preferred is vinyl acetate. Preferred methacrylic esters or acrylic esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, norbornyl acrylate. Particularly preferred are methyl acrylate, methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate. Examples of olefins and dienes are ethylene ,. Propylene and 1,3-butadiene. Suitable vinyl aromatics are styrene and vinyl toluene. A suitable vinyl halide is vinyl chloride.

Preference is given to copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and one or more further vinyl esters, copolymers of vinyl acetate with ethylene and acrylic esters, copolymers of vinyl acetate with ethylene and vinyl chloride, styrene-acrylic acid ester copolymers, styrene-1, 3 Butadiene copolymers.

Particularly preferred are copolymers of vinyl acetate with 10 to 40% by weight of ethylene; Copolymers of vinyl acetate with 5 to 40 wt .-% of ethylene and 5 to 50 wt .-% of a or more further comonomers from the group of vinyl esters having 1 to 15 carbon atoms in the carboxylic acid radical, such as vinyl propionate, vinyldodecanoate, vinyl esters of alpha-branched carboxylic acids having 9 to 13 carbon atoms, such as VeoVa9®, VeoValO®, VeoVall®; Mixed polymers of vinyl acetate, 5 to 40% by weight of ethylene and preferably 5 to 60% by weight of acrylic acid esters of unbranched or branched alcohols having 1 to 15 carbon atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate; and copolymers having from 30 to 75% by weight of vinyl acetate, from 1 to 30% by weight of vinyl laurate or vinyl ester of an alpha-branched carboxylic acid having from 9 to 13 carbon atoms, and from 5 to 30% by weight of acrylic ester of unbranched or branched alcohols with 1 to 15 carbon atoms, in particular n-butyl acrylate or 2-ethylhexyl acrylate, which still contain 5 to 40 wt .-% of ethylene; Copolymers with vinyl acetate, 10 to 40% by weight of ethylene and 1 to 60% by weight of vinyl chloride; wherein the data in wt .-% add up to each 100 wt.%.

Also particularly preferred are acrylic acid ester polymers, such as copolymers of n-butyl acrylate or 2-ethylhexyl acrylate or copolymers of methyl methacrylate with n-butyl acrylate and / or 2-ethylhexyl acrylate and optionally ethylene; Styrene-Äcrylsäureester Copolyinerisate with one or more monomers from the group of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate; Vinyl acetate-acrylic acid ester copolymers with one or more monomers from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and optionally ethylene; Styrene-1,3-butadiene copolymers; wherein the data in wt .-% add up to each 100 wt .-%.

The monomers or the choice of the weight fractions of the comonomers is made in such a way that a Mindestfilmbildetempe- temperature (MFT) of <5 ⁰ C, preferably from -10 ⁰ C <MFT <5 ° C sawn, Sonders preferably from -10 ⁰ C < MFT <O ⁰ C results, wherein the MFT according to DIN 53787 with an aqueous (re) dispersion (solids content 50 wt .-%) of the polymers is determined. The preparation of Homo ™ and copolymers in the form of their aqueous dispersions or water-redispersible powder is carried out in an aqueous medium and preferably by the emulsion polymerization process. The polymers are obtained in the form of aqueous dispersions and, if appropriate, can be converted into corresponding water-redispersible powders by customary drying methods. This procedure is described, for example, in WO 2004/092094 A1, the details of which are part of the application (incorporated herein by reference).

Under low temperatures, the range is generally - 20 ⁰ C to + 5 ° C, preferably from -10 ⁰ C to be understood to +5 ⁰ C, more preferably from -1O ⁰ C to 0 ⁰ C. The hydraulically setting compositions at low temperatures generally contain from 5 to 50% by weight, preferably from 20 to 30% by weight, of hydraulic binder; From 30 to 90% by weight, preferably from 70 to 80% by weight, of fillers; 0.5 to 5 wt .-%, preferably 1 to 3 wt .-%, addition to lower the freezing point; and from 1 to 10% by weight, preferably from 2 to 7% by weight, of homopolymers or copolymers in the form of water-redispersible powders or in the form of aqueous dispersions; and optionally in each case 0.1 to 8 wt .-% setting accelerator or further of said additives; wherein the data in wt .-% on the total weight of the dry mass of the hydraulically setting masses relate, and the data in wt .-% each add up to 100 wt .-%. When using the homopolymers or copolymers in the form of aqueous dispersions, their proportion of dry weight of the polymer is measured.

The invention also dry mortar compositions for the production of hydraulically setting at low temperatures compositions containing an additive for lowering the freezing point of water and homopolymers or copolymers of ethylenically unsaturated monomers, in the form of their water-redispersible powder, the homo- or copolymers a minimum film-forming temperature of <5 ° C. The dry mortar compositions preferably comprise from 5 to 50% by weight of hydraulic binder, from 30 to 90% by weight of fillers, from 0.5 to 5% by weight of additive for lowering the freezing point of water, and from 1 to 10% by weight of homoge- or Mischpoly- merisat in the form of water-redispersible powders, and optionally 0.1 to 8 wt .-% setting accelerator, wherein the data in% by weight based on the total weight of the dry mortar composition.

To prepare the hydraulically setting compositions at low temperatures, it is preferred to use from 15 to 30% by weight of water, based on the total weight of the dry mass of the hydraulically setting compositions.

The preparation of the hydraulically setting materials at low temperatures is not bound to any special procedure or mixing device and can be carried out, for example, in a concrete mixer or a ready mixed concrete mixer. The hydraulically setting masses can be delivered ready mixed as dry mortar composition to the construction site. From the constituents of the recipe can also be made only on site and mixtures are implemented by adding water to hydraulically setting masses.

The hydraulically setting compounds are suitable for the production of concrete, mortar, such as joint mortar, building adhesives such as tile adhesives or adhesives for thermal insulation systems, self-leveling compounds, screed, plastering, for example, rendering plasters for thermal insulation composite systems, or putties. Particularly suitable are the hydraulically setting compositions according to the invention for application in thin layers at low temperatures, since the problem of freezing the masses before completion of the hydration of the hydraulic binder is particularly acute here. Thin layers are to be understood as layer thicknesses of 0, 1 to 50 mm, preferably 1 to 20 mm. These layer thicknesses are especially used in building adhesives, in plasters such as reinforcing cleaning for thermal insulation composite systems and obtained in self-leveling compounds.

The use of homopolymers or copolymers having a minimum film-forming temperature of <5 ° C. for the production of hydraulically setting compounds makes it possible to obtain compositions which have good adhesion and strength properties even at low temperatures.

The following examples serve to further explain the invention:

The following cementitious masses were produced:

Example 1:

A mixture of 300 parts by weight of Portland cement, 670 parts by weight of sand (grain size <0.63 mm), 25 parts by weight of a water-redispersible vinyl acetate-ethylene copolymer powder (MFT according to DIN 53787: 0 ⁰ C) ), 15 parts by weight of calcium formate, 2 parts by weight of methylhydroxyethylcellulose (Walocel MW 40000 PFV) and 3 parts by weight of cellulose fiber (Arbocel PWC 500) with 210 parts by weight of water (T = 25 ⁰ C) to a Mörtelmasse touched.

Comparative Example 2:

The procedure was analogous to Example 1, with the difference that no calcium formate was used.

Comparative Example 3 The procedure was analogous to Example 1, with the difference that no vinyl acetate-ethylene copolymer powder was used.

COMPARATIVE EXAMPLE 4 The procedure was analogous to Example 1, with the difference that instead of the vinyl acetate-ethylene copolymer powder, 50 parts by weight of an aqueous vinyl acetate-ethylene-vinyl chloride dispersion (solids content 50%, MFT according to DIN 53787: 15 ⁰ C) were set and with 185 parts by weight of water (T = 25 ⁰ C) was stirred.

testing:

The mortar compositions according to Example 1 to Comparative Example 4 were each applied at -8 ° C in a layer thickness of 3 mm and over an area of 40 x 40 cm ² on a polystyrene plate.

In the test specimens, the tensile bond strength was ⁽² faces of sawn 50 x 50 mm) after 7 days storage at -8 ⁰ C in accordance with DIN EN 13494:

Example 1: 0.085 N / mm ² (partial rupture / adhesion of polystyrene)

Comparative Example 2; 0.036 N / mm ² (no adhesion of polystyrene)

Comparative Example 3: 0.049 N / mm ² (no adhesion of polystyrene)

Comparative Example 4: 0.047 N / mm ² (no adhesion of polystyrene)

The results show that only unsatisfactory adhesion is obtained in the non-inventive embodiments of the comparative examples. Comparative Example 4 shows the influence of the minimum film-forming temperature MFT on the adhesion when processing at low temperatures - too high MFT of the polymer leads to a drastic reduction in adhesion.

Claims

claims: 1. At low temperatures, hydraulically setting compositions which, in addition to additives for lowering the freezing point of water, also contain homogeneous homopolymers or copolymers of ethylenically unsaturated monomers which are used in the form of their aqueous dispersions or water-redispersible powders, characterized in that Homo- or copolymers have a minimum film-forming temperature of <5 ⁰ C have. 2. At low temperatures hydraulically setting compositions according to claim 1, characterized in that the homo- or copolymers are used in the form of their water-redispersible powders powder. 3. At low temperatures hydraulically setting compositions according to claim 1 or 2, characterized in that one or more copolymers are included from the group containing copolymers of vinyl acetate with ethylene, copolymers of vinyl acetate with ethylene and one or more other vinyl esters, copolymers of vinyl acetate with Ethylene and acrylic acid esters, copolymers of vinyl acetate with ethylene and vinyl chloride, acrylic ester polymers, styrene-acrylic ester Copolymers, and styrene-1,3-butadiene copolymers. 4. At low temperatures hydraulically setting compositions according to claim 1 to 3 containing 5 to 50 wt .-% hydraulic binder, 30 to 90 wt .-% fillers, 0.5 to 5 wt .-% additive for lowering the freezing point of water and 1 to 10 wt .-% homopolymer or copolymer in the form of water-redispersible powders or in the form of aqueous dispersions, and optionally 0.1 to 8 wt .-% setting accelerator, wherein the information in wt .-% on the Total weight of the dry mass of the hydraulically setting masses, and the information in wt .-% each add up to 100 wt .-%. 5. dry mortar compositions for the production of low-temperature hydraulically setting compositions according to claims 1 to 4, comprising additive for lowering the freezing point of water and homopolymers or copolymers of ethylenically unsaturated monomers, in the form of their water-redispersible powder, wherein the homo- or Interpolymers have a minimum film-forming temperature of <5 ° C. 6. dry mortar compositions according to claim 5, containing 5 to 50 wt .-% hydraulic binder, 30 to 90% by weight of fillers, 0.5 to 5 wt .-% additive to lower the freezing point of water and 1 to 10 wt. % Homo- or copolymer in the form of water-redispersible powders, and optionally 0.1 to 8 wt .-% setting accelerator, wherein the data in wt .-% based on the total weight of the dry mortar composition. 7. Use of homopolymers or copolymers with a Minimum film-forming temperature of <5 ^° C. for the production of hydraulically setting compounds according to Claims 1 to 4. 8. A process for the preparation of hydraulically setting at low temperatures compositions according to claim 1 to 4 by Mixing of the ingredients and mixing of water. 9. Use of hydraulically setting at low temperatures compositions according to claim 1 to 4 for the production of concrete, mortars, building adhesives, self-leveling compounds, screeds, plasters, for example Armierungsputze for thermal insulation systems. 10. Use of the hydraulically setting at low temperatures masses according to claim 9 for application in thin Layers of 0.5 to 50 mm, at low temperatures of - 2O ⁰ C to + 5 ° C.