阅读说明：本技术 用于干燥砂浆的高减水粉末制剂 (High water-reducing powder formulation for dry mortar ) 是由 于超 祝佳丽 刘江虹 陈林 于 2019-03-26 设计创作，主要内容包括：本发明涉及粉末形式的PCE类型共聚物,其可以通过喷雾干燥获得,并且容易再分散到水中。所述的粉末形式的PCE类型共聚物的细度和抗结块性能,以及它们的减水潜力和对于坍落度寿命的影响得以改进。本发明还涉及通过喷雾干燥方法生产所述的粉末形式的PCE类型共聚物的生产方法,以及它们用于改进矿物粘结剂组合物和特别是干燥砂浆的用途。(The present invention relates to PCE type copolymers in powder form, which can be obtained by spray drying and are easily re-dispersed in water. The fineness and anti-caking properties of the PCE-type copolymers in powder form are improved, as well as their water-reducing potential and impact on slump life. The invention also relates to a method for producing said PCE type copolymers in powder form by means of a spray-drying process, and to their use for improving mineral binder compositions and in particular dry mortars.)

1. Powdered copolymer P comprising at least 80 w%, preferably at least 85 w%, more preferably at least 90 w% of a PCE-type copolymer, each based on the total weight of the powder, said PCE-type copolymer comprising:

a) a molar parts of structural unit S1 of the formula I

b) b molar parts of structural unit S2 of formula II

c) c molar parts of structural unit S3 of the formula III

d) d molar parts of structural unit S4 of the formula IV

Wherein

Each M independently of the other represents H⁺Alkali metal ions, alkaline earth metal ions, di-or trivalent metal ions, ammonium ions or organic ammonium groups,

each R^uIndependently of one another, represent hydrogen or a methyl group,

each R^vIndependently of one another, represent hydrogen or COOM,

m is 0, 1, 2 or 3,

p is 0 or 1, and p is 0 or 1,

each R¹And each R²Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl or- [ AO]_n-R⁴，

Wherein A ═ C₂-to C₄Alkylene radical, R⁴Representation H, C₁-to C₂₀-alkyl, -cyclohexyl or-alkylaryl,

and n is 2 to 350,

each R³Independently of the other representation of NH₂、-NR⁵R⁶、-OR⁷NR⁸R⁹，

Wherein R is⁵And R⁶Independently of each other represent

C₁-to C₂₀-alkyl, -cycloalkyl

-an alkylaryl group or-an aryl group,

or hydroxyalkyl-or acetoxyethyl- (CH)₃-CO-O-CH₂-CH₂-) or hydroxyisopropyl- (HO-CH (CH)₃)-CH₂-) or acetoxyisopropyl (CH)₃-CO-O-CH(CH₃)-CH₂-)；

Or R⁵And R⁶Together form a ring of which the nitrogen is part, thereby forming a morpholine or imidazoline ring,

R⁷is C₂–C₄-an alkylene group,

each R⁸And R⁹Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl, -aryl or hydroxyalkyl,

and wherein a, b, c and d represent the molar fractions of the structural units S1, S2, S3 and S4, and a/b/c/d/═ 0.1-0.9)/(0.1-0.9)/(0-0.8)/(0-0.8),

and with the proviso that a + b + c + d is 1, and

characterized in that the particle size distribution of the powdered copolymer P is: a D90 value of <250 μm, preferably <225 μm, in particular <210 μm, a D10 value of <60 μm, preferably <50 μm, in particular <40 μm, and a D50 value of 70 to 130 μm, preferably 75 to 120 μm, in particular 80 to 100 μm.

2. Powderized copolymer P according to claim 1, wherein each R¹And R²Independently of one another denote [ AO]_n-R⁴Wherein each R is⁴Independently of one another, from H or CH₃And wherein n is 8-250, more preferably 11-200, even more preferably 20-150, most preferably 30-125, especially 50-115.

3. Powdered copolymer P according to claim 1, wherein the ratio a/b is from 0.5/1 to 15/1, preferably from 1/1 to 11/1, more preferably from 1.5/1 to 9/1, most preferably from 3/1 to 8/1, in particular from 6/1 to 7/1.

4. Powdered copolymer P according to claim 1, characterized in that it further comprises <5 w%, preferably <2 w%, more preferably <1 w%, each based on the total dry weight of the powder, of at least one additive selected from the group consisting of antiblocking agents and antioxidants.

5. Powdered copolymer P according to claim 1, characterized in that its pH is at least 8, preferably at least 10, in particular at least 11, when redispersed in water at a concentration of 40 w%.

6. A process for producing a powdered copolymer P, said process comprising the steps of:

i) preparing an aqueous solution of a copolymer comprising 30-99 w%, preferably 40-95 w%, more preferably 50-90 w% of a PCE-type copolymer, each based on the total weight of the aqueous solution, the PCE-type copolymer comprising:

a) a molar parts of structural unit S1 of the formula I

b) b molar parts of structural unit S2 of formula II

c) c molar parts of structural unit S3 of the formula III

d) d molar parts of structural unit S4 of the formula IV

Wherein

Each M independently of the other represents H⁺Alkali metal ions, alkaline earth metal ions, di-or trivalent metal ions, ammonium ions or organic ammonium groups,

each R^uIndependently of one another, represent hydrogen or a methyl group,

each R^vIndependently of one another, represent hydrogen or COOM,

m is 0, 1, 2 or 3,

p is 0 or 1, and p is 0 or 1,

each R¹And each R²Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl or- [ AO]_n-R⁴，

Wherein A ═ C₂-to C₄Alkylene radical, R⁴Representation H, C₁-to C₂₀-alkyl, -cyclohexyl or-alkylaryl,

and n is 2 to 350,

each R³Independently of the other representation of NH₂、-NR⁵R⁶、-OR⁷NR⁸R⁹，

Wherein R is⁵And R⁶Independently of each other represent

C₁-to C₂₀-alkyl, -cycloalkyl

-an alkylaryl group or-an aryl group,

or hydroxyalkyl-or acetoxyethyl- (CH)₃-CO-O-CH₂-CH₂-) or hydroxyisopropyl- (HO-CH (CH)₃)-CH₂-) or acetoxyisopropyl (CH)₃-CO-O-CH(CH₃)-CH₂-)；

Or R⁵And R⁶Together form a ring of which the nitrogen is part, thereby forming a morpholine or imidazoline ring,

R⁷is C₂-C₄-an alkylene group,

each R⁸And R⁹Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl, -aryl or hydroxyalkyl,

and wherein a, b, c and d represent the molar fractions of the structural units S1, S2, S3 and S4, and a/b/c/d/═ 0.1-0.9)/(0.1-0.9)/(0-0.8)/(0-0.8),

and provided that a + b + c + d is 1,

ii) adding a base to adjust the pH of the solution to at least 7, preferably at least 10,

iii) adding 0.01 to 5 w-%, preferably 0.05 to 2 w-%, more preferably 0.1 to 1 w-% of at least one additive selected from the group consisting of antiblocking agents and/or antioxidants, each based on the weight of the polymer solution,

iv) spray drying the aqueous solution to obtain a powder, and

v) optionally sieving.

7. The process according to claim 6, wherein the powdered copolymer P is characterized by the following particle size distribution: d90<250 μm, preferably <225 μm, in particular <210 μm, D10<60 μm, preferably <50 μm, in particular <40 μm, and D50 is 70 to 130 μm, preferably 75 to 120 μm, in particular 80 to 100 μm.

8. The process according to claim 6, wherein each R in the powdered copolymer P¹And R²Independently of one another denote [ AO]_n-R⁴Wherein each R is⁴Independently of one another, from H or CH₃And wherein n is 50 to 115.

9. Process according to claim 6, in which the ratio a/b in the powdered copolymer P is from 0.5/1 to 15/1, preferably from 1/1 to 11/1, more preferably from 1.5/1 to 9/1, most preferably from 3/1 to 8/1, in particular from 6/1 to 7/1.

10. The process according to claim 6, characterized in that the copolymer in step i) is prepared by a free radical polymerization process.

11. Process according to claim 6, characterized in that the base added in step ii) is selected from LiOH, NaOH, KOH, Mg (OH)₂、Ca(OH)₂Or mixtures thereof.

12. The process according to claim 11, characterized in that the base added in step ii) is Ca (OH)₂And said pH is from 10 to 14.

13. The process according to claim 6, characterized in that step iv) is carried out at a spray drying inlet temperature of not more than 150 ℃, preferably not more than 120 ℃.

14. Use of the powdered copolymer P prepared according to the process of any one of claims 5 to 13 in a mineral binder composition, preferably a cementitious binder composition.

15. Use according to claim 14, characterized in that the mineral binder composition is a dry mortar.

16. Use of the powdered copolymer P prepared according to the process of any one of claims 5-13 for reducing the water demand of a mineral binder composition.

17. Use of the powdered copolymer P prepared according to the process of any one of claims 5-13 for increasing the flowability of a mineral binder composition.

18. Use of the powdered copolymer P prepared according to the process of any one of claims 5 to 13 for improving the slump life of a mineral binder composition.

19. Use of the powdered copolymer P prepared according to the process of any one of claims 5-13 for increasing the compressive strength of a mineral binder composition.

20. A mineral binder composition, in particular a dry mortar, comprising:

a)10-50 w% of at least one mineral binder,

b)0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 2% by weight, in particular 0.15 to 0.8% by weight, of the powdered copolymer P prepared by the process according to any one of claims 5 to 13,

c)0-80 w%, preferably 10-65 w% aggregate

d)0-10 w%, preferably 0.1-6 w% of other additives selected from the group consisting of: plasticizers, superplasticizers, rheology modifiers, retarders, air-entraining agents, deaerators, corrosion inhibitors, fibers, synthetic organic polymers, swell-producing additives, pigments, strength enhancers, water-proofing additives, alkali-aggregate reaction inhibitors, chromate reducing agents, and/or biocides,

each based on the total weight of the mineral binder composition.

21. The mineral binder composition according to claim 20, additionally containing water.

22. A shaped body obtained by curing a mineral binder composition according to any one of claims 20-21.

Technical Field

The present invention relates to a PCE type copolymer in powder form which can be redispersed in water, the production of said PCE type copolymer in powder form and the use of such a powdered PCE type copolymer for modifying dry mortars.

Background

Copolymers (PCEs) of polycarboxylates and polyalkylene glycols have been known for many years as dispersing aids for aqueous dispersions, in particular for aqueous dispersions of mineral binders. The PCE acts as a superplasticizer and reduces the water required to achieve a certain level of fluidity for a given uncured mineral binder composition. Water reduction in mineral binder compositions, particularly cementitious (cementious) compositions, is desirable because it results in less separation of the solid components in the uncured composition and increased compressive strength of the cured composition.

Factory pre-batched (pre-batched) dry mortars are now being used for new construction and renovation work. The advantage of such a dry mortar over a mortar batched at the construction site is an improved consistency of properties, such as flowability, curing kinetics and final strength. The use of PCE for dry mortars requires a dry and hard consistency, preferably in powdered form. Furthermore, the dry, hard consistency of PCE reduces the shipping and storage costs of the PCE, particularly if the dried PCE can be redispersed in water and thus aqueous solutions or dispersions can be easily manufactured at the point of use.

WO2006/133933 discloses PCE type copolymers of ethylenically unsaturated monocarboxylic acid based monomers copolymerized with unsaturated long chain polyalkylene glycol ether based monomers. The copolymer may be spray dried to form a powder. However, the architecture of the disclosed copolymers is not optimal for spray drying processes. Thus producing a powder with a caking tendency and a particle size distribution which is not optimal for use in a dry mortar.

WO2006/129883 discloses a PCE-type copolymer with a degree of neutralization < 50%, which results in improved powdering properties. The powdering can be carried out by different means, including spray drying methods. One disadvantage is that there is still an increased tendency for the powder to agglomerate due to the low degree of neutralization.

WO00/47533 discloses a powdered PCE-based polymer composition containing a mineral carrier, including silica. These powders are reported to have improved powder flow and improved anti-caking properties compared to powders of the same PCE-type copolymer from a spray-drying process. One disadvantage of these powders is that they cannot be easily redispersed to prepare again stable aqueous polymer dispersions.

CN101824125 discloses a PCE type copolymer having polyalkylene glycol chains with a molecular weight of 600-2000 g/mol. A spray-drying process to obtain a powdered product is also disclosed. However, the disclosed spray drying process operates at high temperatures, which requires higher energy input and risks degradation of the PCE-type copolymer during spray drying.

CN101962273 discloses a process for preparing a powdered PCE-type copolymer, which incorporates inorganic particles in a spray drying process. However, large amounts of mineral carrier need to be added to the spray drying process to produce acceptable powder quality. Furthermore, the disclosed spray drying process operates at high temperatures, which requires higher energy input and risks degradation of the PCE-type copolymer during spray drying.

Finally, US7030178 discloses powdered dispersants for hydraulically setting compositions based on PCE-type copolymers: the degree of alkoxylation in the side chain is 45 to 150, the ratio of the monomer having an alkoxylated side chain is 15 to 45 mol%, and the degree of neutralization of the carboxyl group is 70 to 80%. Spray drying is referred to as a method of obtaining the powdered dispersion. One disadvantage is that there is still a significant tendency for the powder to agglomerate due to the degree of neutralization disclosed.

There is therefore a need for a powdered PCE composition that can be easily prepared by spray drying and which overcomes the above-mentioned disadvantages.

Disclosure of Invention

It is an object of the present invention to provide a powdered PCE-type copolymer, which can be obtained by spray drying. In particular, the fineness and anti-caking properties of the powder should be improved over the prior art, as well as the water reduction potential and impact on slump life of the powdered PCE-type copolymer described in the mineral binder composition.

It is another object of the present invention to provide a spray drying process for producing said powdered PCE-type copolymer.

It is a further object of the present invention to provide a process and use of said powdered PCE-type copolymer for improving mineral binder compositions and in particular dry mortars.

Surprisingly it has been found that the object of the present invention can be achieved according to claim 1 by a powdered copolymer P comprising at least 80 w%, preferably at least 85 w%, more preferably at least 90 w% of a PCE-type copolymer, each based on the total weight of the powder, said PCE-type copolymer comprising:

a) a molar parts of structural unit S1 of the formula I

b) b molar parts of structural unit S2 of formula II

c) c molar parts of structural unit S3 of the formula III

d) d molar parts of structural unit S4 of the formula IV

Wherein

Each M independently of the other represents H⁺Alkali metal ions, alkaline earth metal ions, di-or trivalent metal ions, ammonium ions or organic ammonium groups,

each R^uIndependently of one another, represent hydrogen or a methyl group,

each R^vIndependently of one another, represent hydrogen or COOM,

m is 0, 1, 2 or 3,

p is 0 or 1, and p is 0 or 1,

each R¹And each R²Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl or- [ AO [ -o ]]_n-R⁴，

Wherein A ═ C₂-to C₄Alkylene radical, R⁴Represents H, C₁-to C₂₀-an alkyl group, -a cyclohexyl group or-an alkylaryl group,

and n is 2 to 350,

each R³Independently of the other representation of NH₂，-NR⁵R⁶，-OR⁷NR⁸R⁹，

Wherein R is⁵And R⁶Independently of each other represent

C₁-to C₂₀-alkyl, -cycloalkyl

-an alkylaryl group or-an aryl group,

or represents hydroxyalkyl-or acetoxyethyl- (CH)₃-CO-O-CH₂-CH₂-) or hydroxyisopropyl- (HO-CH (CH)₃)-CH₂-) or acetoxyisopropyl (CH)₃-CO-O-CH(CH₃)-CH₂-)；

Or R⁵And R⁶Together forming a ring of which the nitrogen is part, thereby forming morpholine or imidazolineThe shape of the ring is such that,

R⁷is C₂-C₄-an alkylene group,

each R⁸And R⁹Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl,

-an aryl or hydroxyalkyl radical,

and wherein a, b, c and d represent the molar fractions of the structural units S1, S2, S3 and S4, and

a/b/c/d/＝(0.1–0.9)/(0.05–0.9)/(0.0–0.8)/(0.0–0.8)，

and with the proviso that a + b + c + d is 1, and

characterized in that the particle size distribution of the powdered copolymer P is a D90 value <250 μm, preferably <225 μm, in particular <210 μm, a D10 value <60 μm, preferably <50 μm, in particular <40 μm, and a D50 value of 70 to 130 μm, preferably 75 to 120 μm, in particular 80 to 100 μm.

It has been found that the powdered copolymer P described above can be advantageously used in a dry mortar formulation to reduce the water required for drying the mortar and/or to increase the flowability of a composition based on said dry mortar.

Another advantage of the powdered copolymer P according to the invention is that the mineral binder composition comprising said powdered copolymer P has less segregation after mixing with the mixing water.

A further advantage of the present invention is that the powdered copolymer P results in a mineral binder composition having an improved slump life after mixing with water, compared to the same mineral binder composition without the powdered copolymer P but containing a PCE type copolymer of the prior art. Improved slump life means that after a period of time after mixing the mineral binder composition with water, the change in slump spread is minimized.

Finally, one advantage of the powdered copolymer P of the invention is that the compressive strength of the cured mineral binder composition comprising said powdered copolymer P, particularly when measured 1 or 3 days after mixing with water, is increased compared to mineral binder compositions having the same level of flowability but comprising a copolymer of PCE type of the prior art.

Further aspects of the invention are subject matter of further independent claims. Particularly preferred embodiments of the invention are the subject matter of the dependent claims.

Modes for carrying out the invention

The expression "mineral binder" in the context of the present invention especially refers to a binder which reacts in a hydration reaction in the presence of water to form a solid hydrate or hydrate phase. This may 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 (gypsum plaster or white lime). A "mineral binder composition" is thus a composition comprising at least one mineral binder.

According to an embodiment, the mineral binder or mineral binder composition comprises a hydraulic binder, preferably cement. Particularly preferred are cements with a clinker content of > 35% by weight. In particular, the cement is of the type CEM I, II, III (according to standard EN197-1) or a calcium aluminate cement (according to standard EN 14647: 2006-01) or a calcium sulfoaluminate cement or a mixture thereof. The proportion of hydraulic binder in the total mineral binder is advantageously at least 5% by weight, in particular at least 20% by weight, preferably at least 35% by weight, in particular at least 65% by weight. In another advantageous embodiment, the mineral binder consists to an extent of at least 95% by weight of a hydraulic binder, in particular cement clinker.

In an advantageous embodiment, the cement additionally comprises up to 40 w%, preferably up to 35 w%, in particular up to 20 w% of calcium sulphate, each based on the total dry weight of the cement. The calcium sulfate may be present in the form of calcium sulfate hemihydrate, calcium sulfate dihydrate and/or anhydrite.

According to another embodiment, the binder composition comprises a further binder in addition to or instead of the hydraulic binder. They are especially latent hydraulic binders and/or pozzolanic binders. Suitable latent hydraulic and/or pozzolanic binders are, for example, slag, fly ash and/or silica dust. In an advantageous embodiment, the mineral binder comprises 5 to 95% by weight, in particular 5 to 65% by weight, in particular 15 to 35% by weight, of latent hydraulic and/or pozzolanic binder.

As used in the context of the present invention, the term "aggregate" refers to a mineral material that is non-reactive in the hydration reaction of the mineral binder. The aggregate may be any aggregate commonly used in cementitious materials such as concrete, mortar, screed (screened), bottom ash, mud, paint, putty, and the like. Typical aggregates are, for example, rock, crushed stone, gravel, slag, limestone, sand, recycled concrete, perlite or vermiculite.

"dry mortar" means in the context of the present invention a composition containing at least one of the above-mentioned mineral binders and typically aggregates and additives selected from the following group: plasticizers, superplasticizers, rheology modifiers, retarders, air-entraining agents, degassing agents, corrosion inhibitors, fibers, synthetic organic polymers, swell-producing additives, pigments, strength enhancers, water-proofing additives, alkali-aggregate reaction inhibitors, chromate-reducing agents, and/or biocides. The dry mortar may contain a small amount of water. The dry mortar has a solid consistency, in particular a powdered consistency. The dry mortar is typically pre-batched at the factory and sent to the construction site. The dry mortar may be formulated for use as a repair mortar for concrete, as a leveling material, bottom ash, coating, putty, slurry or water shutoff agent, and for water or fire resistant applications.

"particle size distribution" is in the context of the present invention a list of values defining the relative amount of particles present in terms of size. The particle size distribution can be described by different D values. For example, the D10 value is the particle diameter: 10% of the particles of a given distribution are smaller than the diameter and 90% of the particles of the given distribution are larger than the diameter. Likewise, the D90 value is the diameter at which 90% of a given sample contains particles with a diameter less than this value. The term "particle size" in the present invention refers to the median of the particle size distribution of the solid, unless otherwise indicated. This median value is given as the D50 value for a given particle size distribution and constitutes the value of the particle diameter at 50% in the cumulative distribution. The D50 value is generally interpreted as the particle size: wherein 50% of the particles of a given distribution are larger than the particle size and 50% are smaller than the particle size. D50 is therefore a median.

The particle size distribution and thus the different D-values and the particle sizes defined above can be determined in particular by laser light scattering, preferably according to standard ISO 13320: 2009. In particular, a Mastersizer 2000 instrument with a Hydro 2000G dispersion unit and Mastersizer 2000 software, from Malvern instruments GmbH (Germany), can be used for this purpose.

The term "slump life" in the context of the present invention relates to the time after mixing of the mineral binder composition with water until the slump begins to decrease, as measured for example by ASTM C143. In general, a longer slump life is advantageous, since the mineral binder composition will thus work longer.

The powdered copolymer P of the invention comprises at least 80 w%, preferably at least 85 w%, more preferably at least 90 w% of a PCE-type copolymer, each based on the total weight of the powder, said PCE-type copolymer comprising:

a) a molar parts of structural unit S1 of the formula I

b) b molar parts of structural unit S2 of formula II

c) c molar parts of structural unit S3 of the formula III

d) d molar parts of structural unit S4 of the formula IV

Wherein

Each M independently of the other represents H⁺Alkali metal ions, alkaline earth metal ions, di-or trivalent metal ions, ammonium ions or organic ammonium groups,

each R^uIndependently of one another, represent hydrogen or a methyl group,

each R^vIndependently of one another, represent hydrogen or COOM,

m is 0, 1, 2 or 3,

p is 0 or 1, and p is 0 or 1,

each R¹And each R²Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl or- [ AO [ -o ]]_n-R⁴，

Wherein A ═ C₂-to C₄Alkylene radical, R⁴Represents H, C₁-to C₂₀-an alkyl group, -a cyclohexyl group or-an alkylaryl group,

and n is 2 to 350,

each R³Independently of the other representation of NH₂，-NR⁵R⁶，-OR⁷NR⁸R⁹，

Wherein R is⁵And R⁶Independently of each other represent

C₁-to C₂₀-alkyl, -cycloalkyl

-an alkylaryl group or-an aryl group,

or represents hydroxyalkyl-or acetoxyethyl- (CH)₃-CO-O-CH₂-CH₂-) or hydroxyisopropyl- (HO-CH (CH)₃)-CH₂-) or acetoxyisopropyl (CH)₃-CO-O-CH(CH₃)-CH₂-)；

Or R⁵And R⁶Together form a ring of which the nitrogen is part, thereby forming a morpholine or imidazoline ring,

R⁷is C₂-C₄-an alkylene group,

each R⁸And R⁹Independently of one another represent C₁-to C₂₀-alkyl, -cycloalkyl, -alkylaryl, -aryl orA hydroxyalkyl group,

and wherein a, b, c and d represent the molar fractions of the structural units S1, S2, S3 and S4, and

a/b/c/d/═ 0.1-0.9)/(0.05-0.9)/(0-0.8)/(0.0-0.8), particularly a/b/c/d ═ 0.3-0.9)/(0.05-0.7)/(0-0.3)/(0.0-0.4)

And provided that a + b + c + d is 1.

PCE-type copolymers of n-8-250, more preferably n-11-200, even more preferably n-20-150, most preferably n-30-125, in particular n-50-115, have shown to be particularly advantageous for use in dry mortars.

Advantageously, the molar fractions of the structural units S1, S2, S3 and S4 are selected as follows: a/b/c/d is (0.3-0.9)/(0.05-0.9)/(0-0.3)/(0-0.4), preferably (0.3-0.9)/(0.05-0.7)/0/0.

According to a particularly advantageous embodiment, the a/b ratio is between 0.5/1 and 15/1, preferably between 1/1 and 11/1, more preferably between 1.5/1 and 9/1, most preferably between 3/1 and 8/1, in particular between 6/1 and 7/1. An a/b ratio within this preferred limit results in an improved performance of the powdered copolymer P when used in mineral binder compositions and in particular in dry mortars. Powdered copolymers P having an a/b ratio within the preferred limits thus result in a mineral binder or mineral binder composition having an increased initial flowability and a higher compressive strength than powdered copolymers P having other a/b ratios.

According to a particularly advantageous embodiment, R^uAnd R^vEach represents hydrogen or methyl, m is 1, p is 0 and R¹Represents- [ AO]_n-R⁴Wherein A represents C₂-alkylene, n-50-115, and R⁴Is selected from H or CH₃。

The average molecular weight (Mw) of the PCE type copolymer is preferably 5000-150000g/mol, in particular 10000-100000 g/mol. The average molecular weight is measured, in particular, using Gel Permeation Chromatography (GPC) with polyethylene glycol (PEG) as standard.

In particular, the structural units S1, S2, S3 and S4 together have an aggregate molecular weight which amounts to at least 50 wt.%, preferably at least 90 wt.%, in particular at least 95 wt.%, each based on the total dry weight of the PCE-type copolymer.

Methods of producing such PCE-type copolymers are known in the art. Two major methods are used industrially to synthesize such PCE-type copolymers. The first method is a free radical polymerization of ethylenically unsaturated monomers. The side chains of the PCE-type copolymer formed have been attached to the monomer units. PCE type copolymers having the desired structure and properties are obtained by specific monomer selection and ratios, particularly the amount of acrylic and methacrylic monomers in the polymerization reaction solution. Such free radical polymerization and the PCE-type copolymer formed are described, for example, in WO 2012/084954.

In a preferred embodiment of the invention, the PCE-type copolymers are those obtained by radical polymerization. Typical free radical polymerizations are preferably regulated with sodium hypophosphite as the regulator. In a particularly preferred embodiment, the free-radical polymerization is carried out at room temperature.

In a second method, known as polymer-analogous transformation, the polycarboxylic acid backbone is synthesized in a first step. The side chains are then attached to the polycarboxylic acid backbone, for example by esterification, amidation or etherification with alcohols, amines, etc. Such polymer-analogous transformations and the PCE-type copolymers formed are described, for example, in EP1138697 and WO 2005/090416.

It is possible that additional monomers are included in the PCE-type copolymer of the present invention. Examples of such further monomers are styrene, alpha-methylstyrene, vinyl acetate, isobutylene, diisobutylene, cyclopentadiene, ethylene, propylene, N-vinylpyrrolidone, acrylamide, methacrylamide, methyl vinyl ether, ethyl vinyl ether, allyl sulfonic acid, acrylamido-methylpropanesulfonic acid, styrene sulfonic acid, butadiene and acrylonitrile. The sum of the molecular weights of any additional monomers contained in the PCE-type copolymer of the invention is less than 50 w%, preferably less than 10 w%, in particular less than 5 w%, each based on the total dry weight of the PCE-type copolymer.

The powdered copolymer P of the present invention is characterized by having the following particle size distribution: a D90 value of <250 μm, preferably <225 μm, in particular <210 μm, a D10 value of <60 μm, preferably <50 μm, in particular <40 μm, and a D50 value of 70 to 130 μm, preferably 75 to 120 μm, in particular 80 to 100 μm.

The powdered copolymer P of the invention can be obtained by spray drying an aqueous solution of the PCE type copolymer described above.

There is no particular limitation on the concentration of PCE-type copolymer in the aqueous solution prior to spray drying. However, it is preferred that aqueous solutions having a PCE-type copolymer concentration of at least 20 w%, more preferably at least 40 w% and up to 75 w%, each based on the total weight of the aqueous solution, may be used.

The pH of the aqueous solution of PCE-type copolymer is adjusted to >7, preferably >9, in particular >10, prior to spray drying. Such a pH of the aqueous PCE-type copolymer solution used for spray drying results in a more finely divided powdered copolymer P of the invention and a powder with less tendency to cake.

A pH <7 for an aqueous solution of PCE-type copolymer results in increased sticking and caking during spray drying. According to an embodiment, the pH of the aqueous solution of PCE-type copolymer is adjusted according to the number n of recurring units- [ AO ] -. As the number n increases, the pH needs to increase to prevent sticking and caking during spray drying. According to a particularly preferred embodiment, the number n is from 50 to 115 and the pH is adjusted to at least 10.

According to an embodiment, the pH is adjusted by adding an oxide or hydroxide of an alkali metal, an alkaline earth metal or a mixture thereof. Preferably, the pH of the aqueous solution of the PCE-type copolymer is adjusted by the addition of NaOH, KOH, MgO, Mg (OH)₂CaO or Ca (OH)₂Regulated, most preferred is Ca (OH)₂。

Spray drying is a known method for producing dry powders from liquids by a combination of spraying and flash drying of the solution. Drying may be carried out with hot gas, preferably hot air or hot nitrogen. The hot gas can be blown out in the same direction as the sprayed liquid. It is also possible to blow the hot gas out in the opposite direction to the sprayed liquid. The liquid is dispersed by means of a nozzle or an atomizer, the inlet preferably being located in the upper part of the spray tower. The dried powder can be separated from the hot gas by means of a cyclone.

The aqueous solution of PCE-type copolymer is preferably preheated prior to entering the spray dryer. If no gas is used for drying, the PCE type copolymer solution may be introduced into a spray dryer at a pressure between 0.2 and 40 MPa. If a gas is used for drying, the PCE-type copolymer solution may be introduced into a spray dryer at ambient pressure. Preferably, the drying is carried out with hot air or hot nitrogen, preferably by blowing the gas in the same direction as the sprayed liquid. Spray drying can be performed at an inlet temperature of 90-300 deg.C, preferably 100-200 deg.C, more preferably 110-150 deg.C, especially 110-120 deg.C. Lower inlet temperatures have the advantage of lower energy consumption and lower tendency for degradation of PCE-type copolymers. The outlet temperature may be in the range 55 to 200 deg.C, preferably 60 to 150 deg.C, more preferably 65 to 100 deg.C.

The aqueous solution of PCE-type copolymer may be fed to a spray dryer, such as a nozzle, atomizer, or centrifuge, by any means known to those skilled in the art. Any spray dryer known to the person skilled in the art is suitable for producing the powdered copolymer P of the invention. The size of the spray dryer can be selected according to the target throughput.

According to a preferred embodiment, the powdered copolymer P comprises further additives. Preferred additives are anti-caking agents and antioxidants, which stabilize the powder against thermo-oxidative degradation and spontaneous combustion.

Suitable anti-caking agents may be any anti-caking agent known to the person skilled in the art. Examples of anticaking agents include powdered cellulose, magnesium stearate, calcium carbonate, dolomite, clay, kaolin, vermiculite, bentonite, talc, slag, fly ash, silicates or aluminosilicates, and silica, for example fumed silica, precipitated silica, silica gel or silica sol.

Suitable antioxidants may be any antioxidant known to those skilled in the art. Examples of antioxidants are for instance disclosed in WO00/17263 and include alkylated monophenols, alkylated hydroquinones, alkylidene bisphenols, hydroxylated benzyl compounds, phenol-thiodiphenyl ethers, acylaminophenols, phenol esters and phenol amides.

According to embodiments, any such other additives are added prior to the spray drying process as this will result in an enhanced performance of such additives. The additive may be added to an aqueous solution of the PCE-type copolymer prior to spray drying. It is also possible to add one or more additives during the spray drying process, for example via a separate feed nozzle.

According to an embodiment, the content of any such further additive in the powdered copolymer P is less than 5 w%, preferably less than 2 w%, more preferably less than 1.5 w%, in particular less than 1 w%, each based on the total weight of the aqueous solution.

The resulting powder product may be sieved to remove small amounts of agglomerates that could potentially form.

The spray drying process may be carried out continuously or discontinuously.

In a preferred embodiment of the invention, the solid copolymer P is a powder. The powder may be converted into another solid form, for example by pressing. The copolymers P according to the invention can therefore also take the form of granules, shaped blocks, tablets and the like.

The powdered copolymer P of the present invention exhibits an alkaline reaction with water. The pulverulent copolymers P according to the invention can be completely redispersed in water. The pH of such a redispersion in water (with a concentration of the powdered copolymer P according to the invention of 40% by weight) is at least 8, preferably at least 10, in particular at least 11.

As a further aspect, the invention relates to a mineral binder or mineral binder composition, in particular a dry mortar, which contains the powderized copolymer P of the invention. The mineral binder is as defined above. The mineral binder composition may take the form of, for example, a dry composition or a fluid or hardened binder composition (mixed with mix water). The mineral binder composition may also take the form of a fully cured mineral binder composition, such as a shaped body.

The mineral binder or mineral binder composition preferably comprises the powdered copolymer P of the invention in an amount of 0.01-10 w%, preferably 0.05-5 w%, more preferably 0.1-2 w%, especially 0.15-0.8 w%, based on the total weight of the mineral binder. Due to the improved properties of the powdered copolymer P of the present invention, the dosage of said powdered copolymer P in the mineral binder composition can be very low.

The mineral binder composition of the invention, in particular the dry mortar, may additionally comprise an aggregate, preferably sand. Sand is a naturally occurring particulate material that contains finely divided rock or mineral particles. It is available in different forms and sizes. Examples of suitable sands are quartz sand, limestone sand, river sand or crushed aggregates. Suitable sands are described, for example, in the standard ASTM C778 or EN 196-1.

Preferably, at least part of the sand is quartz sand or limestone sand or a mixture thereof, quartz sand being particularly preferred, since it is chemically inert, strong, available in different sizes and the flowability of the composition can be advantageously set.

Typically, sand is provided as particles that pass through different fractions of a screen having clear openings (clearance opening). Preferred are sands in which at least 95% by weight is less than 5mm, more preferably less than 4mm, even more preferably less than 3.5 mm. Large particles may result in improper mixing.

Preferably, at least part of the sand has a particle size of at least 100 μm, more preferably at least 200 μm. Such granulometry enables an optimized granulometric distribution for homogeneous mixing, good rheology of the new mortar and high strength of the hardened mortar.

Preferred sands have a particle size of 0.04 to 5mm, more preferably 0.05 to 4mm and even more preferably 0.05 to 3.6 mm.

A preferred mineral binder composition of the invention, in particular a dry mortar, thus comprises 10-80 w-%, preferably 25-70 w-%, in particular 40-65 w-% sand, based on the total dry weight of the mineral binder composition.

It is advantageous if the mineral binder composition according to the invention, in particular the dry mortar, additionally comprises further additives for mineral binder compositions, in particular cementitious binder compositions. Such additives may be, for example, plasticizers, superplasticizers, rheology modifiers, retarders, air entraining agents, air release agents, corrosion inhibitors, fibers, synthetic organic polymers, swell-producing additives, pigments, strength enhancers, water-proofing additives, alkali-aggregate reaction inhibitors, chromate reducing agents (reducers), and/or biocides.

According to an embodiment, a synthetic organic polymer different from the PCE-type copolymer described above is included in the mineral binder composition of the invention. Synthetic organic polymers may be prepared by free radical polymerization of monomers selected from the group consisting of: ethylene, propylene, butylene, isoprene, butadiene, styrene, acrylonitrile, acrylic acid, methacrylic acid, esters of acrylic acid, esters of methacrylic acid, vinyl esters, vinyl chloride. It is preferred that the synthetic organic polymer is a copolymer synthesized from two or more, preferably two, different monomers. The sequence of the copolymer may be alternating, block or random. Preferred synthetic organic polymers are copolymers of vinyl acetate and ethylene, vinyl acetate and ethylene and methyl methacrylate, vinyl acetate and ethylene and vinyl esters, vinyl acetate and ethylene and acrylic esters, vinyl chloride and ethylene and vinyl laurate, vinyl acetate and vinyl valerate, acrylic esters and styrene and butadiene, acrylic esters and acrylonitrile, styrene and butadiene, acrylic acid and styrene, methacrylic acid and styrene, styrene and acrylic esters, styrene and methacrylic esters.

The glass transition temperature (Tg) of the synthetic organic polymers can vary over a wide range. Suitable synthetic organic polymers may have a Tg of, for example, -50 ℃ to +60 ℃, preferably-45 ℃ to +50 ℃, more preferably-25 ℃ to +35 ℃.

It is possible and in some cases preferred to use a mixture of more than one of said synthetic organic polymers in the composition of the invention.

According to an embodiment, the synthetic organic polymer is used in solid form, for example in the form of a redispersible polymer powder. Such redispersible powders can be produced, for example, by spray drying of the polymer dispersions, as described, for example, in patent application EP 1042391. Suitable redispersible powders are obtainable, for example, from Wacker chemie ag under the trade name Vinnapas. The use of redispersible powders of synthetic organic polymers is preferred in the context of the present invention.

A preferred mineral binder composition of the invention, in particular a dry mortar, thus comprises:

a)10-50 w% of at least one mineral binder,

b)0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 2% by weight, in particular 0.15 to 0.8% by weight, of the powdered copolymer P,

c)0-80 w%, preferably 10-65 w% aggregate,

d)0-10 w%, preferably 0.1-6 w%, of further additives selected from plasticizers, superplasticizers, rheology modifiers, retarders, air-entraining agents, degassing agents, corrosion inhibitors, fibers, synthetic organic polymers, swelling-generating additives, pigments, strength enhancers, water-proofing additives, alkali-aggregate reaction inhibitors, chromate reducing agents, and/or biocides, and

e) optionally water, and optionally a water-soluble polymer,

each based on the total weight of the mineral binder composition.

The mixing of components a) to e) can be carried out in any given order by mixers commonly used for the production of mineral binders, mortars or concretes. The mineral binder composition of the invention, in particular the dry mortar, can be batched beforehand in the factory. It is also possible that the mineral binder composition of the invention, in particular the dry mortar, is mixed at the construction site.

It is preferred in the context of the present invention that the mineral binder composition is a dry composition, such as a dry mortar composition. It is preferred that the mineral binder composition is substantially free of water.

It has been found that a mineral binder or mineral binder composition comprising the above powdered copolymer P has increased flowability, reduced slump loss, increased compressive strength, particularly in the early stages, when compared to the same mineral binder or mineral binder composition with a comparative powdered copolymer.

The above-described powdered copolymer P can therefore be used in a process for increasing the flowability of a mineral binder or mineral binder composition.

The above-described powdered copolymer P can further be used in a process for maintaining the flowability of the mineral binder composition within a defined time after mixing with water, for example within 20min, preferably within 30min, more preferably within 45 min.

The above-described powdered copolymer P can also be used in a process for reducing the water demand of a mineral binder or mineral binder composition.

Finally, the above-described powdered copolymers P can be used in a process for increasing the compressive strength of a mineral binder or mineral binder composition, in particular 1 day and/or 3 days after mixing with water.