Block copolymers as dispersants for alkaline activated binders

Description

Technical field

[0001] The invention relates to the use of a block copolymer as a dispersing agent in a binder composition containing an alkaline activating agent. The invention further relates to a binder composition and a method for its preparation. A further aspect of the invention relates to a molded body obtainable from a binder composition. State of the art

[0002] Cement production generates enormous CO₂ emissions. To reduce these emissions, cement in binder compositions is increasingly being partially replaced by latent hydraulic and / or pozzolanic cement additives such as fly ash, slag, or silica fume. These additives are byproducts of industrial processes and therefore have a positive impact on the CO₂ balance. One problem arising from the use of such additives is that their setting takes significantly longer than that of hydraulic cement, which has a particularly detrimental effect on early strength. To circumvent this problem, latent hydraulic and pozzolanic additives can be activated by adding a suitable activator, such as an alkaline activator.

[0003] To improve the workability of mineral binder compositions at the lowest possible water / binder ratio, it is still common practice to use so-called dispersants as plasticizers. This advantageously modifies both the consistency of the binder composition during processing and its properties in the cured state. For example, polycarboxylate-based comb polymers are known to be particularly effective dispersants. These comb polymers have a polymer backbone with side chains bonded to it. Corresponding polymers are described, for example, in EP 1 138 697 A1 (Sika AG).

[0004] Copolymer mixtures, such as those mentioned in EP 1 110 981 A2 (Kao), are also known as concrete admixtures. These copolymer mixtures are produced by reacting ethylene-unsaturated monomers in a free-radical polymerization reaction, whereby the molar ratio of the two monomers is changed at least once during the polymerization process. FR 2969156 describes the use of copolymers in which monomers can be arranged in blocks and which are produced with methylallyl sulfonate as a transfer agent, as polymeric dispersants for hydraulic binder compositions. WO 2011015780 uses star-shaped block copolymers for this purpose.

[0005] However, as has been shown, polycarboxylate-based comb polymers are generally extremely sensitive to elevated alkaline conditions. Therefore, such dispersants lose their effectiveness after only a short time when used with alkaline activating agents.

[0006] There is therefore a great need for effective dispersing agents that can also be used in alkaline-activated binder compositions. Description of the invention

[0007] The object of the invention is therefore to provide an improved dispersing agent that overcomes the aforementioned disadvantages. The dispersing agent should be usable, in particular, in alkaline-activated binder compositions and remain effective for as long as possible, allowing for effective liquefaction and good processability of the composition.

[0008] Surprisingly, it was found that this problem can be solved by using a block copolymer P according to claim 1. The block copolymer P is characterized in particular by the fact that it comprises at least one first block A and at least one second block B, wherein the first block A is a monomer unit. M1 of formula I (as defined further below), and the second block B has a monomer unit M2 of formula II (as defined further below) and wherein any existing proportion of monomer units M2 in the first block A less than 25 mol%, in particular less than or equal to 10 mol%, is, with reference to all monomer units M1 in the first block A and wherein any existing proportion of monomer units M1 in the second block B less than 25 mol%, in particular less than or equal to 10 mol%, is, with reference to all monomer units M2 in the second block B.

[0009] As has been shown, the block copolymers P used according to the invention are surprisingly insensitive to alkaline conditions, such as those prevalent in alkaline-activated binder compositions with latent hydraulic and / or pozzolanic binders, and thus allow very good processability and high water reduction compared to the use of known dispersing agents, especially compared to comb polymers with statistical distribution of monomers.

[0010] This is particularly evident in the fact that the difference in flowability between prepared comb polymer-containing binder compositions with and without alkaline activating agents is relatively small.

[0011] Thus, the block copolymers according to the invention remain effective as dispersants or liquefiers even in alkaline activated binder compositions for a longer period of time and enable good processability at low water / cement ratios.

[0012] The block copolymers according to the invention can thus be advantageously used specifically for liquefaction, reduction of water requirements and / or improvement of the processability of mineral binder compositions containing alkaline activating agents.

[0013] Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of dependent claims. Ways to implement the invention

[0014] A first aspect of the present invention relates to the use of a block copolymer. Pas a dispersing agent in a binder composition containing at least one mineral binder and one alkaline activating agent, wherein the block copolymer P represents a polymer according to claim 1.

[0015] In block copolymer P Can several different monomer units M1 of formula I and / or several different monomer units M2 Formula II is available.

[0016] The monomer units M1 and any further monomer units in the first block A are distributed particularly statistically or randomly. Likewise, the monomer units M2 and any further monomer units in the second block B especially if statistically or randomly distributed.

[0017] In other words, at least one block is located there A and / or at least one block Bpreferably each exists as a partial polymer with random monomer distribution.

[0018] At least one first block A Advantageously comprises 5-70, in particular 7-40, preferably 10-25 monomer units M1 and / or at least one second block B comprises 5-70, in particular 7-50, preferably 520-40 monomer units M2.

[0019] According to another preferred embodiment, the first block comprises A 25 - 35 monomer units M1 and / or at least one second block B comprises 20-40 monomer units M2.

[0020] A weight-averaged molecular weight Mw of the entire block copolymer PThe molecular weight is in particular in the range of 10,000–150,000 g / mol, advantageously 12,000–80,000 g / mol, and specifically 12,000–50,000 g / mol. In the present context, molecular weights, such as the weight-averaged molecular weight Mw, are determined by gel permeation chromatography (GPC) using polyethylene glycol (PEG) as a standard. This technique is known to those skilled in the art.

[0021] In particular, it is possible to analyze and determine the structure of block copolymers using nuclear magnetic resonance spectroscopy (NMR spectroscopy). Specifically, ¹H and ¹³C NMR spectroscopy allow the sequence of monomer units in the block copolymer to be determined in a known manner based on neighboring group effects and statistical analyses.

[0022] A preferred option is any proportion of monomer units that may be present. M2 in the first block Aless than 15 mol%, in particular less than 10 mol%, specifically less than 5 mol% or less than 1 mol%, based on all monomer units M1 in the first block A. Furthermore, any existing proportion of monomer units M1 in the second block B Advantageously less than 15 mol%, in particular less than 10 mol%, especially less than 5 mol% or less than 1 mol%, based on all monomer units M2 in the second block B. It is advantageous if both conditions are met simultaneously.

[0023] A particularly advantageous feature, for example, is any proportion of monomer units that may be present. M2 in the first block A less than 15 mol% (based on all monomer units) M1 in the first block A ) and any proportion of monomer units that may be present M1 in the second block Bis less than 10 mol% (based on all monomer units) M2 in the second block B ).

[0024] This means the monomer units are located M1 and M2 essentially spatially separated, which benefits the dispersing effect of the block copolymer and is advantageous with regard to the delay problem.

[0025] The first block A consists of all monomer units in the first block A in particular at least 20 mol%, especially at least 50 mol%, specifically at least 75 mol% or at least 90 mol%, from monomer units M1 Formula 1. The second block B consists of all monomer units in the second block B advantageously comprising at least 20 mol%, in particular at least 50 mol%, especially at least 75 mol% or at least 90 mol%, of monomer units M2of formula II. A molar ratio of the monomer units M1 to the monomer units M2 in block copolymer P The value is particularly in the range of 0.5-6, especially 0.7-4, preferably 0.9-3.8, more preferably 1.0-3.7 or 2-3.5. This achieves an optimal dispersing effect in mineral binder compositions.

[0026] Especially when there is a molar ratio of the monomer units M1 to the monomer units M2 In the range of 1.5-6, preferably 1.8-5 or 2-3.5, a good and at the same time particularly long-lasting dispersing effect will be achieved in mineral binder compositions.

[0027] However, other molar ratios may be advantageous for specific applications.

[0028] In particular, R1 ≤ -COOM, R2 ≤ H or -CH3, R3 ≤ R4 ≤ H. This allows the block copolymer to be produced based on acrylic or methacrylic acid monomers, which is economically attractive. Furthermore, such block copolymers offer P In the present context, it offers good dispersing properties with minimal delay in setting time.

[0029] Block copolymers can also be advantageous P with R1 ≤ -COOM, R2 ≤ H, R3 ≤ H and R4 ≤ -COOM. Such comb polymers can be produced based on maleic acid monomers.

[0030] Advantageously, R5 ≠ H or -CH3, R6 ≠ R7 ≠ H, and X = -O-. Such block copolymers P They can be produced, for example, starting from (meth)acrylic acid esters, vinyl, (meth)allyl or isoprenol ethers.

[0031] In a particularly advantageous embodiment, R 2< and R 5< each represent mixtures of 40 - 60 mol-% H and 40 - 60 mol-% -CH 3 .

[0032] According to a further advantageous embodiment, R 1< = -COOM, R 2< = H, R 5< = -CH 3 and R 3< = R 4< = R 6< = R 7< = H.

[0033] In another advantageous embodiment, R 1< = -COOM, R 2< = R 5< = H or -CH 3 and R 3< = R 4< = R 6< = R 7< = H.

[0034] The remainder R 8< in monomer unit M2 consists, with reference to all residues R 8< in the block copolymer P, in particular at least 50 mol%, in particular at least 75 mol%, preferably at least 95 mol% or at least 99 mol%, of a polyethylene oxide. A proportion of ethylene oxide units based on all alkylene oxide units in the block copolymer. P in particular is more than 75 mol%, in particular more than 90 mol%, preferably more than 95 mol% and in particular 100 mol%.

[0035] In particular, R 8< essentially contains no hydrophobic groups, especially no alkylene oxides with three or more carbon atoms. This means, in particular, that the proportion of alkylene oxides with three or more carbon atoms, based on all alkylene oxides, is less than 5 mol%, in particular less than 2 mol%, preferably less than 1 mol% or less than 0.1 mol%. Specifically, no alkylene oxides with three or more carbon atoms are present, or their proportion is 0 mol%.

[0036] R< advantageously represents H and / or a methyl group. A = C2-alkylene is particularly advantageous, where R< represents H or a methyl group.

[0037] In particular, the parameter n = 10 - 150, preferably n = 15 - 100, especially preferably n = 17 - 70, and specifically n = 19 - 45 or n = 20 - 25. Excellent dispersing effects are achieved particularly in the aforementioned preferred ranges.

[0038] Furthermore, it can be advantageous if the block copolymer P at least one more monomer unit MS includes, which differ in particular from the monomer units M1 and M2 chemically distinct. In particular, several different further monomer units can be formed. MS This allows the properties of the block copolymer to be determined. P further modified and adapted, for example, with regard to specific applications.

[0039] The inclusion of at least one additional monomer unit is particularly advantageous. MS a monomer unit of formula III: where R 5'< , R 6'< , R 7'< , m' and p' are defined as R 5< , R 6< , R 7< , m and p; Y, each independently, represents a chemical bond or -O-; Z, each independently, represents a chemical bond, -O- or -NH-; R 9< , each independently, represents an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or an acetoxyalkyl group, each with 1 - 20 C atoms.

[0040] For example, monomer units are advantageous. MS where m' = 0, p' = 0, Z and Y represent a chemical bond and R 9< stands for an alkylaryl group with 6 - 10 C atoms.

[0041] Also suitable, especially for monomer units MS where m' = 0, p' = 1, Y stands for -O-, Z represents a chemical bond and R 9< stands for an alkyl group with 1 - 4 C atoms.

[0042] Furthermore, monomer units MSsuitable where m' = 0, p' = 1, Y represents a chemical bond, Z represents -O- and R 9< represents an alkyl group and / or a hydroxyalkyl group with 1 - 6 C atoms.

[0043] Particularly advantageous is the presence of at least one additional monomer unit. MS made from polymerized vinyl acetate, styrene and / or hydroxyalkyl(meth)acrylate, in particular hydroxyethyl acrylate.

[0044] At least one more monomer unit MS can be part of the first block A and / or the second block B In particular, different monomer units can be found in the different blocks. MS are available.

[0045] If in the first block A present, has at least one further monomer unit MS in the first block AAdvantageously a proportion of 0.001 - 80 mol%, preferably 20 - 75 mol%, especially 30 - 70 mol%, based on all monomer units in the first block A, on.

[0046] Provided in the second block B The present one has at least one further monomer unit MS in the second block B in particular a proportion of 0.001 - 80 mol%, preferably 20 - 75 mol%, specifically 30 - 70 mol% or 50 - 70 mol%, based on all monomer units in the second block B, on.

[0047] According to an advantageous embodiment, in the first block A and / or in the second block B at least one more monomer unit MS present in a proportion of 20 - 75 mol%, specifically 30 - 70 mol%, based on all monomer units in the respective block.

[0048] In the block copolymer P It is a diblock copolymer, consisting of a block Aand a block B.

[0049] A particularly advantageous block copolymer P exhibits at least one or more of the following characteristics: (i) Block A has 7-40, in particular 10-25 or 25-35, monomer units M1 on and block B has 7-50, in particular 20-40, monomer units M2 on. (ii) The first block A consists of all monomer units in the first block A at least 75 mol%, preferably at least 90 mol%, of monomer unit M1 of Formula I; (iii) The second block B consists of all monomer units in the second block B at least 75 mol%, preferably at least 90 mol%, from monomer units M2 of formula II; (iv) A molar ratio of the monomer units M1 to the monomer units M2in the block copolymer lies in the range of 0.5 - 6, preferably 0.8 - 3.5; (v) R 1< stands for COOM; (vi) R 2< and R 5< stand for H or CH 3 , preferably CH 3 ; (vii) R 3< = R 4< = R 6< = R 7< = H; (viii) m = 0 and p = 1; (ix) X = -O- (x) A = C 2 -alkylene and n = 10 - 150, preferably 15 - 50; (xi) R a< = H or -CH 3 , preferably -CH 3 ;

[0050] A diblock copolymer is particularly preferred. P, consisting of blocks A and B, which exhibits at least all features (i) - (iv). A diblock copolymer is further preferred. P which exhibits all features (i) - (xi). A diblock copolymer is even more preferred. P which implements all features (i)-(xi) in their respective preferred embodiments.

[0051] In a special embodiment, these diblock copolymers P also in block A and B additionally, another monomer unit MSas described above, in particular another monomer unit MS of Formula III.

[0052] A block copolymer is specifically a polymer with an essentially linear structure. This means, in particular, that all monomer units of the block copolymer are arranged in a single and / or unbranched polymer chain. Specifically, the block copolymer does not have a star-shaped structure and / or is not part of a branched polymer. In particular, the block copolymer is not part of a polymer in which several, especially three or more, polymer chains oriented in different directions are attached to a central molecule.

[0053] The block copolymer can be in liquid or solid form. It is particularly preferred that the block copolymer be present as a component of a solution or dispersion, wherein the proportion of the block copolymer is particularly 10–90 wt.%, preferably 25–65 wt.%. This makes the block copolymer very easy to add to binder compositions, for example. If the block copolymer is produced in solution, particularly in aqueous solution, further processing can be omitted.

[0054] According to another advantageous embodiment, the block copolymer is in a solid state, particularly in the form of a powder, pellets, and / or sheets. This simplifies the transport of the block copolymers. Solutions or dispersions of the block copolymers can be converted into the solid state, for example, by spray drying.

[0055] Another aspect of the present invention relates to a process for producing a block copolymer comprising a step a) of polymerization of monomers m1 Formula IV as well as step b) of the polymerization of monomers m2 Formula V where R 1< , R 2< , R 3< , R 4< , R 5< , R 6< , R 7< , R 8< , m, p and X are defined as above and where in step a) any existing proportion of monomer m2 less than 25 mol%, in particular less than or equal to 10 mol%, based on the monomers m1, is; and in step b) any existing proportion of monomer m1 less than 25 mol%, in particular less than or equal to 10 mol%, based on the monomers m2, is; and wherein steps a) and b) are performed sequentially, in any order.

[0056] The polymerization in step a) is carried out in particular until 75 - 95 mol%, preferably 85 - 95 mol%, in particular 86 - 92 mol%, of the originally submitted monomers are obtained. m1 have been converted or polymerized.

[0057] In particular, the polymerization in step b) is carried out until 75–95 mol%, especially 80–92 mol%, of the originally introduced monomers are obtained. m2 have been converted or polymerized.

[0058] The turnover of monomers m1 and m2 or the progress of the polymerization in steps a) and b) can be controlled, for example, by means of liquid chromatography, in particular high-performance liquid chromatography (HPLC), in a manner known per se.

[0059] As has been shown, it is advantageous to use the monomers m1 and m2in steps a) and b) up to the conversion rates mentioned above. Furthermore, it is advantageous to carry out steps a) and b) immediately consecutively, regardless of the chosen order. This ensures that the polymerization reaction in steps a) and b) is maintained as effectively as possible.

[0060] The procedure can be carried out, for example, by adding monomers in step a). m1 placed in a solvent, e.g. water, and then formed into a first block A polymerization will occur as soon as the desired conversion of monomer is reached. m1 Once the required concentration is reached (e.g., 75–95 mol%, especially 80–92 mol%; see above), the monomers are added without delay in step b). m2 added and polymerization continued. The monomers are then produced. m2 especially to the block already formed A added, creating a second block Bis formed. The polymerization is advantageously continued until the desired monomer conversion is achieved. m2 (e.g., 75–95 mol%, especially 80–92 mol%; see above). This results, for example, in a diblock copolymer comprising a first block. A and a related second block B receive.

[0061] According to a further advantageous embodiment, at least one further polymerizable monomer is present in step a) and / or in step b). ms before. That at least one more polymerizable monomer ms In this case, it is particularly used together with the monomer m1 and / or the monomer m2 polymerized.

[0062] At least one more polymerizable monomer ms is, regardless of how it is integrated into the block copolymer, in particular a monomer of formula VI where R 5'< , R 6'< , R 7'< , R 9< , m', p', Y and Z are defined as above.

[0063] Advantageous proportions, ratios and configurations of the monomers m1, m2, ms and any further monomers correspond to the aforementioned proportions, ratios and configurations which are related to the monomer units M1, M2 and MS were described.

[0064] The fact that at least one more monomer is added is particularly advantageous. ms selected from vinyl acetate, styrene, N-vinylpyrrolidone and / or hydroxyalkyl(meth)acrylate, in particular hydroxyethyl acrylate.

[0065] Preferably, the polymerization in step a) and / or step b) takes place in an aqueous solution. In particular, the polymerizations in both steps a) and b) take place in aqueous solutions. This also applies accordingly to step c), if it is carried out. As has been shown, this has a positive effect on the dispersing effect of the block copolymer.

[0066] However, it is also possible to use other solvents, such as ethanol.

[0067] The polymerization in step a) and / or b) is advantageously carried out by free radical polymerization, preferably by living radical polymerization, in particular by reversible addition-fragmentation chain transfer polymerization (RAFT). This also applies accordingly to step c), if it is carried out.

[0068] Radical polymerization can be divided into three steps: initiation, growth, and termination. In free radical polymerization, as described, for example, in EP 1 110 981 A2 (Kao), all three steps occur in parallel. The lifetime of the active, growing chains is very short, and the monomer concentration remains essentially constant during chain growth. The polymer chains formed in this way lack active sites suitable for the addition of further monomers. This mechanism therefore does not allow for control over the polymer structure. Consequently, the synthesis of block structures using conventional free radical polymerization is usually not possible.

[0069] In contrast, controlled radical polymerizations or living radical polymerizations are characterized by reversible or even non-existent termination or transfer reactions. After initiation, the active sites are therefore maintained throughout the entire reaction. All polymer chains are formed (initiated) simultaneously and grow continuously. Ideally, the radical functionality of the active site is retained even after complete conversion of the monomers being polymerized. This special property of controlled polymerizations makes it possible to produce well-defined structures such as block polymers through the sequential addition of different monomers (see, for example, [reference])."Polymers: Synthesis, Synthesis and Properties"; Authors: Koltzenburg, Maskos, Nuyken; Publisher: Springer Spektrum; ISBN: 97-3-642-34772-6 and "Fundamentals of Controlled / living Radical Polymerization"; Publisher: Royal Society of Chemistry; Editors: Tsarevsky, Sumerlin; ISBN: 978-1-84973-425-7).

[0070] A radical initiator, preferably an azo compound and / or a peroxide, is used as an initiator for the polymerizations. Suitable peroxides are, for example, selected from the group consisting of dibenzoyl peroxide (DBPO), di-tert-butyl peroxide, and diacetyl peroxide.

[0071] Particularly advantageous as an initiator is an azo compound, such as azobisisobutyronitrile (AIBN), α,α'-azodiisobutyramidine dihydrochloride (AAPH), and / or azobisisobutyramidine (AlBA). Other radical initiators, e.g., sodium persulfate or di-tert-butylhyponitrite, can also be used under certain circumstances.

[0072] If the polymerization takes place in an aqueous solution or in water, α,α'-Azodiisobutyramidine dihydrochloride (AAPH) is advantageously used as the initiator.

[0073] Preferably, one or more representatives from the group consisting of dithioesters, dithiocarbamates, trithiocarbonates, and xanthates are present in step a) and / or step b). These are so-called "RAFT agents," which make it possible to control the polymerization process. This also applies accordingly to step c), if it is carried out.

[0074] In particular, the polymerization in step a), step b) and / or step c) takes place at a temperature in the range of 50 - 95°C, especially 70 - 90°C.

[0075] It is advantageous to work under an inert gas atmosphere, e.g. under a nitrogen atmosphere.

[0076] In a particularly preferred method, step b) is performed before step a).

[0077] According to an advantageous method, step b) is carried out before step a), and no further polymerization steps take place. This allows for the simple production of a diblock copolymer.

[0078] The block copolymer used according to the invention is obtainable, or is produced, in particular by the process described above. In the present context, a "binder composition" is understood to mean, in particular, a composition containing at least one mineral binder.

[0079] The term "mineral binder" refers specifically to a binder that reacts in the presence of water and, if applicable, an activating agent to form solid hydrates or hydrate phases. This can be, for example, a hydraulic binder (e.g., cement or hydraulic lime), a latent hydraulic binder (e.g., slag), a pozzolanic binder (e.g., fly ash), or a non-hydraulic binder (e.g., gypsum or whitewash).

[0080] In this context, the term "latent hydraulic and / or pozzolanic binders" refers specifically to binders that only set or harden hydraulically through the action of additives or activators. These are, in particular, reactive additives of type II according to standard EN 1045-2.

[0081] In this context, an "alkaline activating agent" refers specifically to a substance that acts in a basic or alkaline manner. This is understood to mean, in particular, a substance that, when added to an aqueous solution, is capable of raising its pH value. Specifically, an alkaline activating agent is understood to be a substance suitable for activating the setting or hardening of latent hydraulic and / or pozzolanic binders.

[0082] The binder composition is, in particular, an alkaline-activated binder composition which, in addition to the binder, contains an alkaline activating agent. Specifically, the binder composition contains an alkaline activating agent for activating a latent hydraulic and / or pozzolanic binder. The alkaline-activated binder composition has, in particular, a higher pH value than an analogous binder composition that is not activated or does not contain an alkaline activating agent. The alkaline activating agent may be present in free or dissolved form, e.g., as a salt, and / or may have reacted at least partially with the binder.

[0083] The pH value of the alkaline-activated binder composition, which contains an alkaline activating agent in addition to the binder, has a pH value that is at least 0.1, in particular at least 0.5, specifically at least 1.0, and most specifically at least 1.5 higher than the pH value of the analogous binder composition that is not activated or does not contain an alkaline activating agent. The activating agent is therefore present in a corresponding proportion, or added or used in a corresponding proportion, to achieve such an increase in pH value.

[0084] Preferably, the binder composition contains or consists of a latent hydraulic and / or pozzolanic binder. Possible latent hydraulic and / or pozzolanic binders include, in particular, slags, pozzolans, fly ash, silica dust, volcanic ash, metakaolins, rice husk, burnt shale, and / or calcined clay. Preferred latent hydraulic and / or pozzolanic binders include slags, pozzolans, fly ash, and / or silica dust. Slag and / or fly ash are particularly preferred in this case.

[0085] The binder composition is, in particular, a cementitious or cement-containing binder composition. Specifically, the proportion of cement in the binder composition is at least 5 wt.%, in particular 5–95 wt.%, preferably 60–80 wt.%. Portland cement, for example, is suitable as cement. However, calcium aluminate cements, Portland limestone cements, and / or belite-rich sulfoaluminate cements can also be used, for example.

[0086] In an advantageous embodiment, the binder composition comprises 5–95 wt.%, in particular 15–50 wt.%, and especially preferably 20–40 wt.% of latent hydraulic and / or pozzolanic binder, as well as 5–95 wt.%, preferably 60–80 wt.%, of hydraulic binder. The hydraulic binder is advantageously a cement, in particular a Portland cement.

[0087] The binder composition may, in addition to or instead of the components mentioned above, also include other hydraulic binders, such as hydraulic lime. Likewise, the binder composition may also contain non-hydraulic binders, such as gypsum, anhydrite, and / or whitewash.

[0088] Furthermore, the binder composition can contain inert substances, e.g., pigments, limestone, and / or quartz flour. This is particularly true in combination with latent hydraulic and / or pozzolanic binders. As a result, some of the latent hydraulic and / or pozzolanic binders can be replaced by inert substances, e.g., limestone.

[0089] The alkaline activating agent advantageously comprises an alkali metal salt and / or an alkaline earth metal salt. In particular, it is an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkali metal oxide, an alkali metal oxide, an alkali metal carbonate, an alkali metal sulfate, and / or an alkali metal silicate. The alkaline activating agent is specifically selected from NaOH, Na₂CO₃, Na₂O, Na₂SO₄, sodium silicate, KOH, potassium silicate, CaO, Ca(OH)₂, or mixtures thereof.

[0090] The sodium silicate is specifically a sodium metasilicate or water glass, in particular with the formula Na₂SiO₃. The potassium silicate is specifically a potassium metasilicate or water glass, in particular with the formula K₂SiO₃.

[0091] According to a preferred embodiment, the activating agent comprises or consists of an alkali metal hydroxide, an alkali metal sulfate, and / or an alkali metal silicate. In particular, it comprises sodium sulfate, potassium sulfate, sodium hydroxide, potassium hydroxide, sodium silicate, and / or potassium silicate. Sodium sulfate, sodium hydroxide, and / or sodium silicate are especially preferred.

[0092] The activating agent preferably comprises or consists of an alkali metal salt.

[0093] In a further preferred embodiment, the activating agent is an alkali metal hydroxide, alkali metal carbonate, and / or an alkali metal sulfate. NaOH, KOH, Na₂CO₃, and / or Na₂SO₄ are preferred. An alkali metal hydroxide and / or an alkali metal carbonate is particularly preferred. In particular, the activating agent is NaOH and / or Na₂CO₃, preferably NaOH.

[0094] Such activating agents cause a particularly strong activation of the latent hydraulic and / or pozzolanic binders and are simultaneously compatible with the block copolymers according to the invention. P compatible. In principle, however, other activation agents can also be used.

[0095] Advantageously, the proportion of the alkaline activating agent is 0.001–10 wt.%, in particular 0.1–5 wt.%, and most preferably 0.2–1.5 wt.% or 0.5–1.5 wt.%, in each case based on the weight of the binder. The concentrations refer in particular to the total weight of the binder.

[0096] Another aspect of the invention relates to a binder composition comprising at least one mineral binder, an alkaline activating agent, and a block copolymer as defined above. P.The alkaline activating agent is advantageously an alkaline activating agent as described above. Such binder compositions can be used, for example, together with aggregates such as sand, gravel and / or aggregates for the production of mortars and / or concrete.

[0097] The mineral binder advantageously contains or consists of a latent hydraulic and / or pozzolanic binder.

[0098] The binder composition is, in particular, a processable and / or water-mixed mineral binder composition.

[0099] The weight ratio of water to binder in the binder composition is preferably in the range of 0.25 - 0.7 wt.%, in particular 0.26 - 0.65 wt.%, preferably 0.27 - 0.60 wt.%, and specifically 0.28 - 0.55 wt.%.

[0100] The block copolymer PIt is advantageously used in a proportion of 0.01–10 wt.%, in particular 0.1–7 wt.%, and specifically 0.2–5 wt.%, based on the binder content. The proportion of the block copolymer P This refers to the block copolymer P In itself. In the case of a block copolymer P In the form of a solution, the solids content is decisive.

[0101] An additional aspect of the present invention relates to a molded body, in particular a component of a structure, obtainable by curing a binder composition as described above after the addition of water.

[0102] A structure can be, for example, a bridge, a building, a tunnel, a road, or a runway.

[0103] Another aspect of the present invention relates to a method for producing a binder composition. In this process, a mineral binder, which in particular contains or consists of a latent hydraulic and / or pozzolanic binder, is combined with a block copolymer. P, as described above, and mixed with an alkaline activating agent.

[0104] According to a preferred method, the mixing water for the binder composition is premixed with the activating agent and then the block copolymer is added. P The block copolymer is then added in a subsequent step. The mixing water containing the block copolymer is then added. P and, if necessary, the activating agent mixed with the binder. This has been done with a view to achieving the best possible effectiveness of the block copolymer. P The binder composition has proven to be advantageous.

[0105] However, it is also possible to first mix the activating agent with the mineral binder, e.g. with some of the mixing water, and then add the block copolymer afterwards. P to mix in, for example with another part of the mixing water.

[0106] Further advantageous embodiments of the invention can be derived from the following exemplary embodiments. Examples of implementation 1. Examples of polymer manufacturing processes 1.1 Diblock copolymer P1

[0107] For the production of the diblock copolymer P1In a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and inert gas inlet tube, 57.4 g of 50% methoxy-polyethylene glycol-1000-methacrylate (0.03 mol) and 24.9 g of deionized water are placed using RAFT polymerization. The reaction mixture is heated to 80°C with vigorous stirring. A gentle stream of inert gas is passed through the solution during heating and throughout the remaining reaction time. 756 mg of 4-cyano-4-(thiobenzoyl)pentanoic acid (2.7 mmol) are then added to the mixture. After the substance has completely dissolved, 135 mg of AIBN (0.82 mmol) are added. From this point onward, the conversion is regularly determined by HPLC.

[0108] Once the conversion, based on methoxy polyethylene glycol methacrylate, exceeds 80%, 5.85 g of acrylic acid (0.08 mol) are added to the reaction mixture. The mixture is allowed to react for a further 4 hours and then cool. A clear, slightly reddish, aqueous solution with a solids content of approximately 40% remains. 1.2 Diblock copolymer P2

[0109] For the production of the diblock copolymer P2Using RAFT polymerization, 347.21 g of 48% methoxy polyethylene glycol 2000 methacrylate (0.08 mol) and 112.2 g of deionized water are placed in a round-bottom flask equipped with a reflux condenser, stirrer, thermometer, and an inert gas inlet tube. The reaction mixture is heated to 80°C with vigorous stirring. A gentle stream of inert gas is passed through the solution during heating and throughout the remaining reaction time. 2.27 g of 4-cyano-4-(thiobenzoyl)pentanoic acid (0.008 mol) are then added to the mixture. After the substance has completely dissolved, 404 mg of AIBN (0.0024 mol) are added. From this point onward, the conversion is regularly determined by HPLC.

[0110] Once the conversion, based on methoxy polyethylene glycol methacrylate, exceeds 80%, 23.78 g of acrylic acid (0.33 mol) are added to the reaction mixture. The mixture is allowed to react for a further 4 hours and then cool. A clear, slightly reddish, aqueous solution with a solids content of approximately 40% remains. 1.3 Statistical polymer P3

[0111] In a reaction vessel equipped with a mechanical stirrer, thermometer and reflux condenser, 234 g of water, 60 g of maleic anhydride (0.6 mol), 520 g of allyl polyethylene glycol ether (0.47 mol; average molecular weight 1100 g / mol) were mixed. 2. Mortar mixtures 2.1 Production

[0112] The mortar mixture used for testing purposes has the dry composition described in Table 1: Table 1: Dry composition of mortar mix component Quantity [g] Cement (CEM I 42.5 N; Normo 4; available from Holcim Switzerland) 525 g Slag (Löruns) 225 g Limestone filler 141 g Sand 0-1 mm 738 g Sand 1-4 mm 1107 g Sand 4-8 mm 1154 g

[0113] To prepare a mortar mix, the sands, limestone filler, cement, and slag were dry-mixed for 1 minute in a Hobart mixer. Within 30 seconds, the mixing water (water-to-cement ratio w / c = 0.44) was added, and the mixture was continued for another 2.5 minutes. The total wet mixing time was 3 minutes in each case.

[0114] The mixing water was pre-mixed with the respective polymer (proportion: 0.32 wt.%; based on the polymer's solids content and the cement content) and, if necessary, a basic activator (NaOH; 1.25 wt.% based on the binder content (cement plus slag)) before being added to the mortar mix. If both a polymer and a basic activator were added, the basic activator was added to the mixing water before the polymer. 2.2 Mortar tests

[0115] To determine the dispersing effect of the polymers, the spread (ABM) of prepared mortar mixtures was measured at various times. The spread (ABM) of the mortar was determined according to EN 1015-3.

[0116] Furthermore, the influence of polymers on the hydration behavior of mineral binder compositions was determined by measuring the temperature development over time of mortar mixtures after mixing with water. The temperature measurement was performed under adiabatic conditions using a thermocouple as a temperature sensor in a known manner. All samples were measured under identical conditions. In this case, the time [t(TM)] elapsed from mixing the mortar mixture until reaching the temperature maximum occurring after the induction or resting phase is considered the measure of the setting time. 2.3 Results of the mortar tests

[0117] Table 2 provides an overview of the mortar tests performed and the results obtained. Test V1 is a zero test conducted for comparison purposes without the addition of a polymer.

[0118] The experiments clearly show that when using block polymers P1-P2 (see experiments) V4-V7 ) the percentage change in the spreading mass due to the addition of NaOH is clearly lower, at least in the early stages, than when using the reference polymer. P3 (see experiments) V2 and V3 ) . Furthermore, it is evident that, at the same dosage, the block copolymers according to the invention exhibit a clearly better liquefaction performance in absolute terms, which is also maintained at a relatively high level over longer periods.

[0119] The results presented thus indicate that the block copolymers according to the invention are advantageous in several respects compared to known polymers. In particular, the polymers according to the invention achieve high dispersing and liquefaction effects, which can be maintained at a practically relevant level for a comparatively long time. Furthermore, the polymers according to the invention are clearly less susceptible to alkaline activating agents than conventional polymers.

[0120] However, the embodiments described above are to be understood merely as illustrative examples, which can be modified as desired within the scope of the invention.

Claims

1. Use of a block copolymer P as dispersant in a binder composition comprising at least one mineral binder and an alkaline activating agent, wherein a fraction of the alkaline activating agent based on the weight of the binder is 0.001 - 10 wt%, and wherein the block copolymer P comprises at least one first block A and at least one second block B, the first block A comprising a monomer unit M1 of the formula I, and the second block B containing a monomer unit M2 of the formula II where R1 is -COOM, R2, R3, R5 and R6, in each case independently of one another, are H or an alkyl group having 1 carbon atom, R4 and R7, in each case independently of one another, are H or -COOM, M, independently of any other, is H+, an alkali metal ion, an alkaline earth metal ion, a di- or trivalent metal ion, an ammonium ion or an organic ammonium group; m is 0, 1 or 2, p is 0 or 1, X, in each case independently of any other, is -O- or - NH-, where for at least 99 mol% of all monomer units M2, X is -O-, R8 is a group of the formula -[AO]n-Ra, where A is C2- to C4-alkylene, Ra is H, a C1- to C20-alkyl group, -cyclohexyl group or -alkylaryl group, and n is 2 - 250, more particularly 10 - 200; and where any fraction of monomer units M2 present in the first block A is less than 25 mol%, more particularly less than or equal to 10 mol%, based on all the monomer units M1 in the first block A, and where any fraction of monomer units M1 present in the second block B is less than 25 mol%, more particularly less than or equal to 10 mol%, based on all the monomer units M2 in the second block B, and wherein the block copolymer P is a diblock copolymer consisting of a block A and a block B.

2. Use according to Claim 1, characterized in that the at least one first block A of the block copolymer P comprises 5 - 70, more particularly 7 - 40, preferably 10 - 25 monomer units M1 and / or in that the at least one second block B of the block copolymer P comprises 5 - 70, more particularly 7 - 40, preferably 10 - 25 monomer units M2.

3. Use according to at least one of Claims 1 - 2, characterized in that the first block A of the block copolymer P comprises 25 - 35 monomer units M1 and / or in that the at least one second block B of the block copolymer P comprises 10 - 20 monomer units M2.

4. Use according to at least one of Claims 1 - 3, characterized in that the block copolymer P has a molar ratio of the monomer units M1 to the monomer units M2 in the range of 0.5 - 6, more particularly 0.7 - 4, preferably 0.9 - 3.8, more preferably 1.0 - 3.7 or 2.0 - 3.5.

5. Use according to at least one of Claims 1 - 4, characterized in that the first block A of the block copolymer P consists to an extent of at least 20 mol%, more particularly at least 50 mol%, in particular at least 75 mol%, especially at least 90 mol%, based on all the monomer units in the first block A, of monomer units M1 of the formula I, and / or in that the second block B of the at least one block copolymer P consists to an extent of at least 20 mol%, more particularly at least 50 mol%, in particular at least 75 mol%, especially at least 90 mol%, based on all the monomer units in the second block B, of monomer units M2 of the formula II.

6. Use according to at least one of Claims 1 - 5, characterized in that the block copolymer P comprises at least one further monomer unit MS which in particular is a monomer unit of the formula III: where R5', R6', R7', m' and p' are defined like R5, R6, R7, m and p in Claim 1; Y, in each case independently of any other, is a chemical bond or -O-; Z, in each case independently of any other, is a chemical bond, -O- or -NH-; R9, in each case independently of any other, is an alkyl group, cycloalkyl group, alkylaryl group, aryl group, hydroxyalkyl group or an acetoxyalkyl group, in each case having 1 - 20 carbon atoms.

7. Use according to at least one of Claims 1 - 6, characterized in that in the block copolymer P, n is 10 - 150, more particularly 15 - 100, preferably 17 - 70, especially 19 - 45.

8. Use according to at least one of Claims 1 - 7, characterized in that the mineral binder comprises or consists of a latent hydraulic and / or pozzolanic binder.

9. Use according to Claim 8, characterized in that the binder composition has 5 - 95 wt%, more particularly 15 - 50 wt%, more preferably 20 - 40 wt% of latent hydraulic and / or pozzolanic binder, and also 5 - 95 wt%, preferably 60 - 80 wt%, of hydraulic binder, more particularly cement.

10. Use according to at least one of Claims 1 - 9, characterized in that the activating agent comprises an alkali metal hydroxide, alkali metal carbonate and / or alkali metal sulfate, more particularly NaOH, KOH, Na2CO3 and / or Na2SO4.

11. Binder composition comprising at least one mineral binder, an alkaline activating agent, wherein a fraction of the alkaline activating agent based on the weight of the binder is 0.001 - 10 wt%, and a block copolymer P as defined in any of the preceding claims.

12. Method for producing a binder composition according to Claim 11, by mixing a mineral binder with a block copolymer P as defined in the preceding claims and with an alkaline activating agent.

13. Shaped article, more particularly a constituent of a construction, obtainable by fully curing a binder composition according to Claim 12 following addition of water.