NOVEL SHRINKAGE-REDUCING AGENTS FOR MINERAL BINDERS
The invention relates to the use of carboxylic acid-based polyoxyalkylenes as low-emissions shrinkage reducers in mineral binders, to methods of reducing shrinkage and to corresponding compositions.
1 . A shrinkage-reducing agent comprising a polyoxyalkylene of the formula (I)
wherein
R is independently an a-valent, linear or branched, saturated, monounsaturated or polyunsaturated, aliphatic, cycloaliphatic or aromatic hydrocarbyl radical having 3 to 38 carbon atoms, where the hydrocarbyl radical is substituted by a polyoxyalkylene radicals A,
a is from 1 to 4,
n is from 0 to 40,
m is from 0 to 40,
wherein
the sum total of n and m=4 to 80, where the units that n and m refer to are distributed in the polyether chain either in blocks or randomly and the units that n and m refer to constitute the mean values of the possible statistical distribution of the actual structures present.
2 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), the R radical is independently an aliphatic hydrocarbyl radical having from 3 to 38 carbon atoms, where the carbon chain is terminally substituted by 1 or 2 polyoxyalkylene radicals A and a is the number of polyoxyalkylene radicals A and is 1 or 2.
3 . The shrinkage-reducing agent according to claim 1 , wherein the R radicals derive from a fatty acid or a dimer fatty acid.
4 . The shrinkage-reducing agent according to claim 1 , wherein the R radicals derive from hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, 2-ethylhexanecarboxylic acid, isononanoic acid, 3,5,5-trimethylhexanecarboxylic acid, neodecanoic acid, isotridecanecarboxylic acid, isostearic acid, undecylenoic acid, oleic acid, linoleic acid, ricinoleic acid, linolenic acid, benzoic acid, cinnamic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanecarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid or the dimer fatty acids that derive from the aforementioned unsaturated carboxylic acids.
5 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), a is less than 3.
6 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), m=2 to 30 and n=2 to 30, and the sum total of n and m is 6 to 40.
7 . The shrinkage-reducing agent according to claim 1 , wherein the polyoxyalkylenes of the formula (I) have a weight-average molar mass of 300 to 15 000 g/mol.
8 . The shrinkage-reducing agent according to claim 1 , wherein the polyoxyalkylenes of the formula (I) have been applied to a support.
9 . The method of reducing shrinkage of building materials comprising mineral binders, especially cementitious binders, preferably of mortar, screed, concrete or slurries, wherein at least one polyoxyalkylene of the formula (I) according to the provisions of claim 1 is added to an unhardened building material mixture.
10 . The method according to claim 9 , wherein the polyoxyalkylene of the formula (I) is added to the building material mixture in an amount of 0.001% to 6.0% by weight, based on the dry weight of the mineral binder.
11 . The method according to claim 9 , wherein the building material mixture comprises customary admixtures and/or additives and/or aggregate.
12 . The method according to claim 9 , wherein
i) the at least one polyoxyalkylene of the formula (I), mineral binders, admixtures, additives and/or aggregate are mixed without addition of water and water is added to the premix thus obtained at a later juncture, or
ii) the individual components are mixed together with water.
13 . The method according to claim 9 , wherein the at least one polyoxyalkylene of the formula (I) is mixed with the mineral binder and/or the rock flour during the process of production or delivery of the building material.
14 . The building material composition comprising
i) at least one mineral binder, preferably a cementitious binder, and
ii) at least one polyoxyalkylene of the formula (I)
according to the provisions from claim 1 .
15 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), a is less than 1.
16 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), m is from 4 to 20, and n is from 4 to 20, and the sum total of n and m is from 8 to 20.
17 . The use according to claim 1 , wherein the polyoxyalkylenes of the formula (I) have a weight-average molar mass of 500 to 2500 g/mol.
18 . The method according to claim 9 , wherein the polyoxyalkylene of the formula (I) is added to the building material mixture in an amount of 0.1% to 3% by weight, based on the dry weight of the mineral binder.
19 . The shrinkage-reducing agent according to claim 2 , wherein the R radicals derive from hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, 2-ethylhexanecarboxylic acid, isononanoic acid, 3,5,5-trimethylhexanecarboxylic acid, neodecanoic acid, isotridecanecarboxylic acid, isostearic acid, undecylenoic acid, oleic acid, linoleic acid, ricinoleic acid, linolenic acid, benzoic acid, cinnamic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanecarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid or the dimer fatty acids that derive from the aforementioned unsaturated carboxylic acids.
20 . The shrinkage-reducing agent according to claim 1 , wherein, in formula (I), the R radical is independently an aliphatic hydrocarbyl radical having from 5 to 17 carbon atoms, where the carbon chain is terminally substituted by 1 or 2 polyoxyalkylene radicals A and a is the number of polyoxyalkylene radicals A and is 1 or 2.