EP3938212A1

EP3938212A1 - Mineral binder composition for 3d printing

Info

Publication number: EP3938212A1
Application number: EP20709604.1A
Authority: EP
Inventors: Gary Boon; Maxime LIARD; Didier Lootens; Lolita HAUGUEL
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2019-03-15
Filing date: 2020-03-13
Publication date: 2022-01-19
Also published as: MX2021010729A; CL2021001902A1; US12180117B2; WO2020187742A1; CO2021013312A2; US20220162124A1; US20250066251A1; BR112021013832A2; SG11202107329XA

Abstract

The invention relates to a dry mineral binder composition comprising cement and mineral fillers for the manufacture of molded parts by way of 3D printing. The binder composition additionally contains at least one aluminum sulfate-based accelerator, at least one polycarboxylate ether-based super-plasticizer and at least one rheology additive.

Description

MINERAL BINDING COMPOSITION FOR 3D PRINTING

Technical area

The invention relates to a mineral binder composition, its use for the 3D printing of moldings and a method for

Production of moldings from the binder composition by means of 3D printing.

State of the art

Structural concrete is usually poured into formwork for shaping and allowed to harden in it. The manufacture of the formwork causes

Material costs and time, the shaping is limited and formwork is often treated with environmentally harmful formwork oils. The concrete typically takes several hours before sufficient strength is achieved to be able to remove the formwork.

Concrete construction without formwork using 3D printing is therefore becoming increasingly important.

The term “3D printing”, also called “generative manufacturing process”, “generative manufacturing” or “freeform construction”, refers to processes in which a spatial object or a spatial object is created through targeted spatial deposition, application and / or solidification of material Molded body is produced. The

The material is deposited, applied and / or solidified, in particular using a data model of the object to be produced, and in particular in layers or layers. The material is typically applied using a 3D printer. Every object is generative

Manufacturing process made from several layers. A shapeless material is used to manufacture an object, which is particularly subjected to chemical and / or physical processes (e.g. melting, polymerizing, sintering, curing).

The 3D printing of cementitious binder compositions, especially mortar or concrete, poses a particular challenge. Typically a water-based cementitious binder is used for this

Composition prepared and conveyed to a movable print head of a 3D printer. The computer controlled, in at least one

Movable in spatial direction, the printhead deposits the material in a specified quantity and speed, typically in layers, until the desired one

Molding is completed.

The demands on the theological properties and the development of strength of the cementitious binder composition are high. In order to achieve an economical production speed, 3D printing requires that the water-containing binder composition can be easily conveyed to the print head. Since no formwork is used, the material must have sufficient strength after application from the printhead in order to retain the given shape. In addition, the material must develop rapidly in strength so that before the next horizontal layers above, the lower, load-bearing layers are applied, they have sufficient strength so that they are not deformed by the weight of the layers above. Rapid strength development is particularly important for molded parts that are supposed to reach a height of 0.5 m, 1 m, 2 m or more.

In addition, the top layer in each case is advantageously not yet fully cured when the next layer above is applied, so that a good bond between the individual layers is ensured.

Cement achieves its strength through reaction with water in a chemical process known as cement hydration. This reaction is also known as the setting of the cement. Typically, the time between mixing the cement with water and achieving sufficient strength to be dimensionally stable and stable is in the range of several hours.

Concrete or mortar mixes have already been used for 3D printing that contain very little water and are therefore very rigid. Such mixtures can only be conveyed over short distances and with high pump pressure and the like The molded body produced often contains imperfections, such as air inclusions, is optically inhomogeneous and / or has a poor bond between the individual applied layers.

EP 3 421 201 describes a cementitious mixture for 3D printing. The

Mixture comprises a hydraulic binder, latent hydraulic additives, fillers, aggregates, further additives and water. The aggregates must have a particle size of less than 1 mm and the viscosity of the mixture is between 4Ό00 and 35Ό00 Pa s. The mortar mixing time is very long, and the printing speed and printing height are low.

WO 2019030255 describes a method for 3D printing in which a water-containing mineral binder composition is conveyed to a continuous mixer with a pump and mixed with an aqueous setting accelerator in the continuous mixer. The now accelerated binder composition is applied in layers by means of a print head. Mixing the accelerator into the binder

composition with a continuous mixer which is preferred on

The printhead is mounted is an additional step and greatly increases the cost of installing the printer.

The previous methods do not solve the problem satisfactorily. Either the production speed is low and / or the printing height is small, or the cost is high. The optical aspect of the molded body is often poor and / or the strength is insufficient.

There is therefore a need for cementitious compositions for 3D printing which overcome the aforementioned disadvantages as far as possible.

Presentation of the invention

The object of the present invention is to provide an improved mineral

To provide binder composition for 3D printing. The composition should in particular be an efficient, simple, inexpensive, enable reliable and rapid application. This, if possible, with a high quality of the applied layers in terms of strength development and optical uniformity.

Surprisingly, this object is achieved by a composition as described in claim 1.

The dry mineral binder composition is easy to use

handle. It only has to be mixed with water and can be easily applied using a 3D printer.

The dry mineral binder composition already contains

Accelerator, the addition of accelerator at or just before the print head, is not necessary.

The dry mineral binder composition can be processed quickly with water to form a homogeneous water-containing binder composition. This enables continuous mixing, which is advantageous for homogeneous processability and high print quality.

The stability of the applied layers is high and they quickly achieve sufficient strength to support additional layers applied over them without deforming. This enables rapid printing, also in the vertical direction.

By using an accelerator based on aluminum sulphate, a rapid strength development of the binder mixture is achieved after mixing with water.

Aluminum sulfate based accelerators are typically used for

Shotcrete used. Here, an aqueous accelerator solution or suspension is added to a non-accelerated concrete mix directly at the spray nozzle. The accelerated concrete is sprayed on a wall and immediately stiffens.

Surprisingly, an accelerator based on aluminum sulphate can be used in the binder composition according to the invention without leading to an immediate stiffening of the mixture after mixing with water. The water-based binder composition remains easy to process over a sufficient period of time so that it can be easily processed using 3D Printer can be applied and can also form a good bond with a later applied new layer.

Surprisingly, by using at least one

Polycarboxylate ethers with a corresponding content of carboxylic acid groups, the setting behavior of the mineral binder composition accelerated with aluminum sulfate can be controlled in a targeted manner. This allows the setting behavior of the binder composition to the respective

Conditions such as, for example, the ambient temperature, the desired vertical printing speed and the desired printing height can be adjusted only by varying the amount of polycarboxylate ether.

For example, for printing a shaped body with a large horizontal extension and, as a result, a smaller vertical extension

Build-up speed compared to a molded body with horizontally smaller expansion and higher vertical build-up speed, the amount of

Polycarboxylate ether in the binder composition can be different in order to ensure optimal strength development for both applications. This is very advantageous because, by varying a single component, a binder composition adapted to the respective setting parameters can be made available.

Surprisingly, with the inventive mineral

Binder composition high printing speed, printing heights over a meter and more, as well as homogeneous and aesthetic moldings without cracks can be obtained.

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

The invention relates to a dry mineral binder composition comprising cement and mineral fillers for the production of molded bodies by means of 3D printing, characterized in that the

Binder composition also comprises at least one accelerator based on aluminum sulfate, at least one superplasticizer based on a polycarboxylate ether and at least one rheological aid, the polycarboxylate ether, assuming all carboxylic acid groups are present as free acid, at least 1 mmol, in particular at least 1.2 mmol, in particular at least 1.8 mmol, Carboxylic acid groups per gram dry

Having polycarboxylate ethers.

In this document, “3D printing”, also known as “freeform construction”, is understood to be a form-free, shaping process. Here, a deformable material is applied in several layers or in smaller portions, one on top of the other and, if necessary, next to one another, layer by layer, thus creating three-dimensional objects. The construction is computer-controlled according to given dimensions and shapes. After the material which is deformable during application has hardened, a solid shaped body is formed. In 3D printing, the layers are typically not applied by spraying the material.

In the present document, “mineral binder” is understood in particular to mean a binder which, in the presence of water, reacts in a hydration reaction to form solid hydrates or hydrate phases.

In the present document, “mineral binder composition” is accordingly understood to mean a composition containing at least one mineral binder. This contains in particular the binder, fillers and optionally one or more additives. In the present document, “dry mineral binder composition” means a free-flowing mineral binder composition with a moisture content of less than 0.5% by weight.

In the present document, “water-containing mineral binder composition” means a mineral binder composition mixed with water, in particular in fluid form.

In the present document, “polycarboxylate ether” is understood to mean a

Comb polymer comprising a backbone of hydrocarbons with attached carboxylic acid groups or their salts and also to the

Backbone of covalently bound polyalkylene glycol side chains (= polyether side chains). The side chains are attached to the polycarboxylate backbone in particular via ester, ether, imide and / or amide groups.

The amount of carboxylic acid groups in the polycarboxylate ether is expressed in millimoles of carboxylic acid groups in one gram of the

Polycarboxylate ethers (mmol / g) understood. For this purpose, any salts of the carboxylic acids that may be present are counted among the carboxylic acid groups and the weight of the polycarboxylate ether is used in non-neutralized form. Carboxylic acid esters are not counted among the carboxylic acid groups here, not even if they are in latent form, i.e. if they are in an alkaline medium, e.g. at pFH = 12, can be hydrolyzed.

The amount of carboxylic acid groups in the polycarboxylate ether can be

be determined for example by titration. Methods for titrating carboxylic acid groups in a polymer are known per se to the person skilled in the art.

The amount of carboxylic acid groups in the polycarboxylate ether can be

for example, can also be calculated.

If polycarboxylate ethers are used which have been produced by a polymer-analogous conversion of a polycarboxylate, the calculation is carried out according to the following formula (I): 1000

(I)

in which

CS = the amount of carboxylic acid groups in one gram of the

Polycarboxylate ethers in mmol / g,

Mn (BB) = average molecular weight of the polycarboxylate backbone in g / mol,

M (monomer) = average molecular weight of the monomers of

Polycarboxylate backbone in g / mol,

m (BB) = weight of the polycarboxylate backbone in g during the production of the polycarboxylate ether,

n _a (SK) = amount of substance of the a. Side chain in moles in the production of the

Polycarboxylate ethers (corresponds to the quotient from the initial weight of the a.

Side chain in the production of the polycarboxylate ether and its average molecular weight),

Mn (polymer) = mean molar mass of the polycarboxylate ether in g / mol.

The mean molar mass of the polycarboxylate ether used is determined in particular using GPC against PEG as the standard.

A calculation example is presented below:

A polycarboxylate ether is produced by transesterification of a

Polymethacrylic acid with an average molecular weight of 7-00 g / mol with a methoxy-terminated polyethylene glycol with an average molecular weight of 1-00 g / mol. The initial weight of the polyacrylic acid is 100 g, the weight of the methoxy-terminated one

Polyethylene glycol is 150 g. This information results in:

Mn (BB) = 7-00 g / mol

M (monomer) = 84 g / mol

m (BB) = 100 g

n _a (SK) = 150/1 Ό00 g / mol = 0.15 g / mol

The mean molar mass of the resulting polymer is determined by GPC analysis to be 17,500 g / mol. From this it follows: Mn (polymer) = 17,500 g / mol From this, CS can be calculated as follows:

83.3

83.3 1 19 0.15

1 +

CS = 0.15 1000 4.16

17500

If polycarboxylate ethers are used which have been prepared from alkylenically unsaturated monomers by radical polymerization, the calculation is carried out using the following formula (II): 1000

(II)

in which

CS = the amount of carboxylic acid groups in one gram of the

Polycarboxylate ethers in mmol / g,

ns = amount of moles of the carboxylic acid groups contained in the monomers used to produce the polycarboxylate ether,

m (Monomera) = weight of the a. Monomer in g in the production of the

Polycarboxylate ethers.

A calculation example is presented below:

A polycarboxylate ether is produced by radical polymerization of a mixture of 100 g of acrylic acid and 200 g of an ethoxylated allyl ether with an average molecular weight of 2,500 g / mol. This information gives: ns = 100/72 g / mol = 1.39 g / mol,

m (Monomera) = 100 + 200 g = 300 g,

From this, CS can be calculated to be 1.39 / 300 ^* 1000 mmol / g = 4.63 mmol / g.

In the present document, “rheological aid” is understood to mean a substance which can change the theological properties of the water-containing mineral binder composition, in particular it increases the viscosity, the flow limit and / or the thixotropy. In the present document, “dimensional stability” is understood to mean a material property in which the material changes the individual dimensions by a maximum of 10% after shaping, provided that no external force other than

Gravity acts on the molded material.

In the present document, “stability” is understood to mean the strength that a hardenable material has after application before hardening.

Any available type of cement or a mixture of two or more types of cement can be used as cement, for example the cements classified under DIN EN 197-1: Portland cement (CEM I), Portland composite cement (CEM II), Floch-furnace slag cement (CEM III), Pozzolan cement ( CEM IV) and composite cement (CEM V). Of course, cements that are produced according to an alternative standard such as the ASTM standard are equally suitable.

Portland cement CEM I or CEM II according to DIN EN 197-1 is preferred.

Portland cement CEM I 42.5 or CEM I 52.5 is particularly preferred. Such cements give good strength and good workability.

For the production of white or colored moldings, it is advantageous if a white cement CEM I or CEM II is used.

The dry mineral binder composition advantageously also contains at least one latently hydraulic or pozzolanic binder,

especially metakaolin and / or silica dust (amorphous Si02). The latently hydraulic or pozzolanic binder is preferably present in 0.1 to 10% by weight, in particular in 0.5 to 5% by weight, based on the total weight of the dry binder composition. These additives can improve the processability of the water-based binder composition and the

Increase the strength of the cured binder composition.

The dry mineral binder composition contains mineral fillers. Fillers are chemically inert solid particulate materials and are available in different shapes, sizes and as different materials, which vary from the finest sand particles to large coarse stones. In principle, all fillers that are commonly used for concrete and mortar are suitable. Examples of particularly suitable fillers are aggregates, gravel, sand, in particular quartz sand, limestone sand and slag sand, crushed stones, calcined pebbles or light fillers such as expanded clay, expanded glass, foam glass, pumice stone, perlite and vermiculite. Further advantageous fillers are fine or very fine fillers such as ground limestone or dolomite,

Aluminum oxide, silica fume (amorphous S1O2), quartz powder or ground

Steel slag with no or only weak latent hydraulic reactivity.

Preferred fillers are selected from the group consisting of quartz sand, quartz powder, limestone sand, ground limestone and ground steel slag. The filler preferably comprises at least one finely ground crystalline filler, in particular limestone. This can promote the early strength development of the binder composition mixed with water.

The particle size of the fillers depends on the application and is in the range from 0.1 μm to 32 mm and more. Different particle sizes are preferably mixed in order to optimally adjust the properties of the binder composition. Fillers made from different materials can also be mixed. The particle size can be determined with the help of a sieve analysis.

Fillers with particle sizes of at most 8 mm, more preferably at most 5 mm, even more preferably at most 3.5 mm, most preferably at most 2.2 mm, in particular at most 1.2 mm or at most 1.0 mm are preferred.

The particle size is determined in particular by the planned layer thickness of the applied layers in 3D printing. A maximum particle size of the fillers is sensibly as large as the planned one

Layer thickness during application.

The binder composition preferably contains 20 to 40% by weight, in particular 22 to 36% by weight, based on the total weight of the dry binder composition, fine fillers with a particle size of less than 0.125 mm.

Suitable fillers with a small particle size are particularly fine

Quartz sands, quartz flour, ground calcium carbonate or ground

Steel slag.

The binder composition preferably contains 1 to 10% by weight, more preferably 2 to 5% by weight, of ground calcium carbonate with a

Particle size of less than 0.01 mm. The very fine calcium carbonate improves the workability of the binder composition mixed with water and can increase the strength development of the binder composition.

In special applications, fillers with particle sizes up to 32 mm, more preferably up to 20 mm, most preferably up to 16 mm, can also be used. Particle sizes can be determined using sieve analysis in accordance with the ASTM C136 and ASTM C117 standards.

The mineral fillers are preferably 45 to 85% by weight, in particular 50 to 80% by weight, based on the total weight of the dry ones

Binder composition, present.

The dry mineral binder composition contains one

Aluminum sulfate based accelerator.

The accelerator causes the strength to develop rapidly

Binder composition after mixing with water.

The accelerator advantageously contains at least 30% by weight, preferably at least 35% by weight, more preferably at least 40% by weight,

Aluminum sulphate, calculated as aluminum sulphate Flydrat Al2 (S04) 3-16 FI2O.

In addition to the aluminum sulfate, the accelerator can advantageously contain other components such as amino alcohols, alkali and alkaline earth nitrates, alkali and

Alkaline earth nitrites, alkali and alkaline earth thiocyanates, alkali and alkaline earth halides, alkali carbonates, glycerine, glycerine derivatives, other aluminum salts,

Aluminum hydroxides, alkali and alkaline earth hydroxides, alkali and alkaline earth silicates, Alkali and alkaline earth oxides or alkali and alkaline earth salts of formic acid, or mixtures thereof, contain.

A particularly preferred binder composition consists of

At least 90% by weight, in particular at least 95% by weight, accelerator is composed of aluminum sulfate hydrate or is aluminum sulfate hydrate.

The binder composition is preferably free from amino alcohols.

Amino alcohols have an intense, unpleasant odor, can be hazardous to health and lead to uncontrolled stiffening of the binder composition after mixing with water.

The aluminum sulfate-based accelerator is preferably present in 0.1 to 2% by weight, more preferably in 0.3 to 1.5% by weight, in particular in 0.4 to 1.0% by weight, based on the total weight of the dry binder composition.

Such a dosage of the accelerator, in particular in combination with a polycarboxylate ether, leads to a rapid development of the strength of the binder composition mixed with water without impairing the processability for the printing process.

The dry mineral binder composition comprises at least one superplasticizer based on polycarboxylate ether. The at least one polycarboxylate ether contains carboxylic acid groups in the form of free, that is, non-neutralized, carboxylic acid groups and / or in the form of their alkali metal and / or alkaline earth metal salts.

A polycarboxylate ether which has no other anionic groups in addition to the carboxylic acid groups is preferred.

A polycarboxylate ether whose side chains consist of at least 80 mol%, preferably at least 90 mol%, especially preferably 100 mol%, of ethylene glycol units is further preferred.

The side chains preferably have an average molecular weight M w in the range from 500 to 10Ό00 g / mol, preferably 800 to 8Ό00 g / mol, particularly preferably 1Ό00 up to 500 g / mol. There can also be side chains with different

Molecular weights be present in the polycarboxylate ether.

Preferred is a polycarboxylate ether of methacrylic acid and / or

Acrylic acid units and monomer units with polyalkylene glycol chains is built up.

The at least one polycarboxylate ether preferably has a medium one

Molecular weight Mw of 800-0000 g / mol, in particular 1000-0000 g / mol, measured against polyethylene glycol standards.

Such polycarboxylate ethers have a good effect, even in the presence of the accelerator based on aluminum sulfate and with a low water content

Processability of the binder composition mixed with water.

A low water content causes a high strength of a cured

Molded body.

In combination with the accelerator based on aluminum sulfate, such polycarboxylate ethers act particularly well as a means of controlling the setting and / or setting of the water-containing binder composition.

The at least one polycarboxylate ether can be added as an aqueous solution to the

Binder composition are introduced, for example by

Spray on the fillers before mixing with the mineral

Binder.

The at least one polycarboxylate ether is preferably present as a powder in the dry binder composition.

In a preferred embodiment of the invention, the at least one polycarboxylate ether has a block or gradient structure. Under

In the present document, “polycarboxylate ether with a block or gradient structure” is understood to mean a polymer in which the monomer units are present in a non-statistical sequence, that is, the sequence is not obtained by chance. Included in the polycarboxylate ether of block or gradient structure

at least one section of monomer units comprising polyalkylene glycol side chains and no or hardly any monomer units with carboxylic acid groups and at least one section of monomer units with carboxylic acid groups and no or hardly any monomer units with polyalkylene glycol side chains. Such block or gradient polymers therefore have sections with a high density of anionic groups and sections which contain no or only a few anionic groups.

Surprisingly unfold polycarboxylate ethers with block or

Gradient structure works very quickly as a liquefier. They are therefore particularly well suited for applications in which the mixing time of

Binder composition and water is very short, especially for continuous mixing.

Polycarboxylate ethers with a block or gradient structure also cause the water-containing binder composition to have a low viscosity. This improves the pumpability of the binder composition mixed with water. The good liquefying effect of the polycarboxylate ethers with a block or gradient structure also surprisingly persists in the inventive one

Binder composition only for a few minutes, which is advantageous for 3D printing because it makes the

Binder composition can be achieved directly after mixing with water and good stability of the water-containing binder composition after application.

The at least one polycarboxylate ether is preferably present in 0.02 to 5% by weight, more preferably in 0.05 to 4% by weight, in particular in 0.1 to 3% by weight, calculated as dry polymer based on the total weight of the dry binder composition.

The metering of the at least one polycarboxylate ether in the binder composition is advantageously adapted to the respective printing task. The printing parameters, such as typically the desired height of the molding, the thickness of the applied layers, the printing speed and the expected ambient temperature, are advantageously recorded before printing and then using empirical values, tables and / or computer program determines the optimal amount of polycarboxylate ether in the binder composition.

Polycarboxylate ether in the binder composition can be different in order to ensure optimal strength development for both applications.

The total amount of polycarboxylate ether in the dry is advantageous

Binder composition provided.

However, it can also be advantageous, in particular in the case of applications that are small in terms of quantity and / or when the printing parameters are variable, especially due to temperature fluctuations, waiting pauses, or when the printing is done

Molded body has different parts with different dimensions if only part of the polycarboxylate ether in the dry

Binder composition is present and another part, in each case adapted to the current printing conditions, is added during or shortly after mixing with water.

The further part of the polycarboxylate ether is advantageously added together with the mixing water in a continuous mixing process.

The dry binder composition can thus be produced in large quantities, which is advantageous, and the adjustment of the properties of the

water-containing binder composition to the respective

Printing conditions takes place simply and inexpensively just before application.

The dry mineral binder composition contains at least one organic and / or inorganic rheological aid.

Suitable rheology aids are in particular modified starch,

Amylopectin, modified cellulose, microbial polysaccharides, galactomannans, Alginate, tragacanth, polydextrose, superabsorbent or mineral

Thickener.

The rheological aid is preferably selected from the group consisting of modified starches, modified celluloses, microbial polysaccharides, superabsorbents and mineral thickeners.

The total amount of rheological aid in the dry binder composition is preferably from 0.01 to 5% by weight, based on the

Total dry binder composition weight.

The modified starch is preferably a starch ether, in particular

Hydroxypropyl starch, carboxymethyl starch or carboxymethyl hydroxypropyl starch. The modified starch is preferably present in 0.01 to 2% by weight based on the total weight of the dry binder composition.

The modified cellulose is preferably methyl cellulose, ethyl cellulose,

Carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose or methylhydroxyethyl cellulose and is preferably present in 0.01 to 2% by weight based on the total weight of the dry binder composition.

The microbial polysaccharide is preferably welan gum, xanthan gum or diutan gum and is preferably present in 0.01 to 0.1% by weight, based on the total weight of the dry binder composition.

The superabsorbent is preferably selected from the group comprising

Polyacrylamide, polyacrylonitrile, polyvinyl alcohol, isobutylene-maleic anhydride copolymers, polyvinylpyrrolidone, homo- and copolymers of monoethylenically unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, sorbic acid, maleic acid, fumaric acid, itaconic acid, preferably polyacrylic acid, which can be partially or completely neutralized Copolymers and terpolymers of the monoethylenically unsaturated carboxylic acids mentioned with vinylsulfonic acid, (meth) acrylamidoalkylsulfonic acids, allylsulfonic acid, vinyltoluenesulfonic acid, Vinylphosphonic acid, (meth) acrylamide, N-alkylated (meth) acrylamide, N-methylol (meth) acrylamide, N-vinylformamide, N-vinyl acetamide, vinyl pyrrolidone, hydroxyalkyl (meth) acrylate, ethyl acrylate, methyl acrylate, (meth) acrylic acid esters of polyethylene glycol monoallyl ethers, Vinyl acetate and / or styrene.

The superabsorbent homo- and copolymers can be linear or branched, the copolymers can be present randomly or as block or gradient polymers. The homopolymers and copolymers are preferably also crosslinked. The superabsorbent is preferably polyacrylic acid, which can be partially or completely neutralized and is crosslinked.

If present, the superabsorbent is preferably present in 0.01 to 0.5% by weight, in particular in 0.05 to 0.3% by weight, based on the total weight of the dry binder composition.

The mineral thickener is preferably a special silicate or clay mineral, in particular a bentonite or sepiolite, preferably sepiolite.

The mineral thickener is preferably present in 0.1 to 1% by weight based on the total weight of the dry binder composition.

The binder composition preferably contains at least two, more preferably at least three, different rheological aids.

The rheological aid is particularly suitable, the dimensional stability of the

to ensure water-based binder composition and to give an applied layer sufficient stability to carry one or more additional layers without changing the shape significantly before the hydration of the cement begins.

Preferred combinations of two or more rheology aids are:

- modified cellulose and microbial polysaccharide;

- modified cellulose and superabsorbents;

- microbial polysaccharide and superabsorbent; - microbial polysaccharide, superabsorbent and mineral thickener;

- modified cellulose, microbial polysaccharide and superabsorbent;

- modified cellulose, microbial polysaccharide, superabsorbents and

mineral thickener.

By combining two or more rheological aids, the different thickening properties of the rheological aids can be optimally matched to one another. This results in good processability with good stability of the water-containing binder composition.

A combination of rheological aids which comprises at least one superabsorbent is particularly preferred.

The superabsorbent also acts as a means of reducing shrinkage, which is particularly advantageous.

The dry mineral binder composition preferably also contains 0.1 to 5% by weight, preferably 0.1 to 4.5% by weight, more preferably 0.5 to 3% by weight, calcium sulfoaluminate, based on the total weight of the dry binder composition.

A suitable calcium sulfoaluminate is available, for example, in Denka CSA # 20, available from Newchem, Switzerland.

The calcium sulfoaluminate can, especially in the preferred dosage, on the one hand increase the early strength development of the aqueous binder composition and at the same time reduce shrinkage.

A higher content of calcium sulfoaluminate in the binder composition can reduce the ultimate strength of a printed molded article and increase the cost of the composition.

Surprisingly, the combination of calcium sulfoaluminate and rheological aid, in particular a superabsorbent, can reduce the shrinkage of the Binder composition can be greatly reduced after application.

Shrinkage can lead to the formation of cracks in the molded article produced. Cracks can reduce the durability of the printed structures and disrupt the visual impression.

The dry mineral binder composition advantageously also contains at least one further additive for reducing shrinkage selected from the group consisting of glycols, polyglycols and water-storing materials, such as, in particular, porous stones, ground bricks and / or ground cement stone.

The dry mineral binder composition preferably also contains at least one defoamer, in particular selected from the group consisting of oil-based defoamers, in particular defoamers based on mineral oils, vegetable oils or white oils which can contain a wax and / or hydrophobic silica, silicone-based defoamers which, for example, Alkoxylation or fluorination can be modified, alkyl esters of phosphoric or phosphonic acid, alkoxylated polyols, especially ethoxylated diols, fatty acid-based defoamers, especially mono- and diglycerides of fatty acids and alkoxylated fatty alcohols, and mixtures thereof.

The defoamer is preferably selected from the group comprising

ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, a combination of

Fatty alcohol alkoxylates and polysiloxane and a combination of mineral oil and a silicone oil containing hydrophobic silica.

The defoamer is preferably present in 0.01 to 1% by weight, in particular 0.1 to 0.8% by weight, based on the total weight of the dry binder composition.

The use of a defoamer is advantageous because it prevents or reduces the formation of air voids when the dry binder composition is mixed with water. Air voids can promote the water-containing binder composition interfere with the print head, and reduce the strength in the cured molded body and pores interfere with the visual impression of the molded body.

Surprisingly, the defoamer also reduces the shrinkage and thus the formation of cracks in the cured molding.

Optionally, the dry mineral binder composition can also contain at least one further additive, for example a concrete additive and / or a mortar additive. The at least one further additive includes in particular a flow agent, a retarder, a wetting agent, fibers, a dye, a preservative, a further accelerator

Dispersion polymer, a cationic polymer, a cationic polycondensate, a cationic comb polymer, an air entrainer, another

Shrinkage reducer or a corrosion inhibitor, or combinations thereof.

The flow agent is in particular sodium gluconate, lignosulfonate, sulfonated naphthalene-formaldehyde condensate, sulfonated melamine-formaldehyde condensate, sulfonated vinyl copolymer, polyalkylene glycol

Phosphonate groups, polyalkylene glycol with phosphate groups or a

aromatic condensate with phosphonate groups and polyalkylene glycol chains.

The use of hardening retarders can be advantageous, since this extends the processing time of the water-based binder composition. The hardening retarder is preferably a hydroxycarboxylic acid, in particular tartaric acid, citric acid or gluconic acid, a sugar, in particular sucrose, a phosphate or a phosphonate, or their salts or mixtures thereof.

A preferred binder composition comprises:

- 10 to 50% by weight, preferably 12 to 40% by weight, in particular 15 to

35% by weight, cement, especially Portland cement, - 0.1 to 5% by weight, preferably 0.1 to 4.5% by weight, more preferably 0.5 to 3% by weight, calcium sulfoaluminate,

- 0 to 10% by weight, preferably 0.1 to 5% by weight, of at least one latent hydraulic binder, in particular metakaolin and / or silica dust,

- 45 to 85% by weight, preferably 50 to 80% by weight, mineral

Fillers,

- 0.1 to 2% by weight of an accelerator based on aluminum sulfate,

- 0.02 to 5% by weight of at least one polycarboxylate ether,

- 0.01 to 2% by weight of at least one rheological aid,

- 0.01 to 1% by weight of at least one defoamer and

- 0 to 10% by weight further additives,

based on the total weight of the dry binder composition.

Another object of the invention is a water-containing mineral binder composition, obtained by mixing the dry mineral binder composition, as described above, with water, in particular with 10 to 25% by weight, preferably 12 to 22% by weight, more preferably 14 to 20% by weight %, Water based on that

Total dry binder composition weight.

Mixing with water is preferably carried out in a continuous mixer. This ensures a high production speed. In addition, in the event of a possible interruption, there does not have to be a discontinuous

Mixing device already mixed material must be disposed of.

The start of setting of the water-containing binder composition is advantageously between about 10 minutes and 1 hour, and the end of setting between about 30 minutes and 3 hours, measured in accordance with DIN EN 196-3 at 20 ° C with an automatic Vicat apparatus.

The water-containing binder composition advantageously achieves a strength of at least 0.05 MPa, preferably at least 0.08 MPa, in particular at least 0.1 MPa, at 20 ° C. one hour after application, and after 3 hours, preferably 2 hours, at least 0.5 MPa, in particular 1 MPa. The strength can be determined using a penetration method such as described in ASTM C 403.

Such a strength development of the water-containing binder composition is particularly advantageous for the efficient production of moldings.

The invention also relates to the use of the water-containing mineral binder composition for the production of moldings by means of 3D printing.

Another object of the invention is a method for applying a mineral binder composition, in particular by means of 3D printing, comprising the steps:

- Providing a dry mineral binder composition, as described above, water and optionally at least one further additive;

- adding the dry mineral binder composition,

Water and the optionally at least one further additive in a mixing device, in particular in a mixing chamber of the

Mixing device, with a feed device;

- Mixing the dry mineral binder composition with water and the optionally at least one further additive in the mixing device to obtain a water-containing mineral

Binder composition;

- Feeding the water-containing mineral binder composition through a conveying line to a print head movable in at least one spatial direction using a conveying device;

- Applying the water-based mineral

Binder composition with the movable printhead. This method is advantageous

- -at least one other additive of the dry mineral

Binder composition added together with the water, the at least one further additive being another

Polycarboxylate ether, a retarder and / or another

Rheology aid, in particular a polycarboxylate ether, comprises, and

- The metering of the at least one further additive in

Depending on printing conditions such as horizontal and vertical printing speed, print height and ambient temperature.

The at least one further additive is preferably a polycarboxylate ether, a retarder and / or a rheological aid, as described above.

The further polycarboxylate ether is preferably identical to the polycarboxylate ether in the dry mineral binder composition, but is here in particular as an aqueous solution.

However, it can also be advantageous if the further polycarboxylate ether is not identical to the polycarboxylate ether in the dry mineral binder composition. In particular, the other differs

Polycarboxylate ether of the polycarboxylate ether in the dry mineral binder composition by the number of carboxylic acid groups per g of polymer and / or the average molecular weight Mw of the polyalkylene glycol side chains or it has a block or gradient structure if the polycarboxylate ether in the dry binder composition does not have a block or gradient structure .

The further polycarboxylate ether, if present, is preferably added in 0.01 to 5% by weight, in particular in 0.08 to 4% by weight, based on the weight of the water-containing binder composition. The retarder, if present, is preferred in 0.01 to 3% by weight, in particular in 0.03 to 2% by weight, based on the weight of the

hydrous binder composition added.

The further rheology aid, if present, is preferably added in 0.01 to 2% by weight, based on the weight of the water-containing binder composition

With such a method, the strength development of the binder composition can be continuously adapted to the printing process, resulting in a high quality structure of the molded body despite the possible

Temperature fluctuations, unwanted or deliberate changes in the

Printing speed and / or interruptions in the printing process allows.

In a further preferred embodiment of the present invention, at least one property of the applied material is determined during the printing process and, if the property deviates from the specified setpoint values, the further additive, in particular a polycarboxylate ether, is added

Retarder and / or a rheological aid, metered into the mixing device.

In a further embodiment of the present invention, at least one further rheology aid, in particular a modified cellulose and / or a microbial polysaccharide, preferably in the form of an aqueous solution, can be introduced into the water-containing binder composition, in particular by means of a pump attached to or just in front of the print head . This can cause unwanted fluctuations in the stability of the

water-containing binder composition are balanced.

With the method according to the invention, molded bodies can be produced homogeneously and quickly by applying them in layers.

The printing speed, that is, the speed of the horizontal

Movement of the print head, preferably at least 20 mm per second, more preferably at least 30 mm per second, in particular at least 40 mm per second.

It can also be advantageous, especially for fast printing and fast production of the molded body, when the printing speed is higher,

in particular more than 50 mm per second, 100 mm per second, 150 mm per second, 200 mm per second up to 500 mm per second.

The vertical printing speed depends on the horizontal dimension of the molding, the thickness of the individual applied layers and the horizontal printing speed. The period of time between the application of the lower layer and the next layer above is preferably between about 1 second and 30 minutes, in particular between 10 seconds and 10 minutes.

Another object of the present invention is a molded body produced by mixing a dry mineral

Binder composition, as described above, with water and optionally further additives, application of the water-containing mineral binder composition in layers with a 3D printer and hardening of the binder composition.

The height of an individual layer, typically measured in a direction essentially perpendicular to the planes formed by individual layers, in particular in the vertical direction, is preferably 0.2 mm to 200 mm, more preferably 1 mm to 100 mm, in particular 2 mm to 50 mm .

The total height of the shaped body or the thickness of all individual layers of the shaped body taken together is preferably 0.01 m to 100 m or more, more preferably 0.1 m to 80 m, even more preferably 0.3 m to 30 m, in particular 0.5 m to 10 m.

The shaped body preferably has a height of at least 0.5 m, more preferably at least 1 m, in particular at least 1.5 m or 2 m. As long as it is still workable, the surface of the shaped body can be smoothed, repaired or specially deformed with suitable tools. This can be done as part of the machine production, or manually as a separate step. The surface can also be given a functional or decorative

Coating are provided, for example with a color.

The shaped body can also, as long as it is still workable, with suitable

Tools are cut. So can holes, especially for

Fixed openings, door openings, line passages or also cuts, in particular for later processing steps, are introduced into the molded body.

The shaped body produced by the method according to the invention can have almost any shape. The molded body is, for example, a building, a prefabricated part for a building, a component, a brickwork, a bridge, a column, a decorative element such as artificial mountains, reefs or sculptures, a basin, a fountain or a tub. The

Shaped bodies represent a full shape or a hollow shape, with or without a bottom.

The shaped body can be created directly on site and no longer moved after application. The shaped body can also be created at another location, in particular special in a factory. This is preferably done on a pad to which he is not liable. After curing, the molded body can be transported to the desired location.

Details and advantages of the invention are given below with reference to FIG

Embodiments and with reference to schematic drawings

described. Brief description of the figures

Fig. 1 shows: a schematic representation of an exemplary system for

Applying a water-based mineral

Binder composition.

FIG. 2 shows a graphical representation of the development of strength over time of water-containing cementitious binder compositions.

Embodiments

In FIG. 1, an exemplary system 1 for carrying out a method according to the present invention for applying the water-containing mineral binder composition is shown schematically.

The system 1 comprises a movement device 2 with a movable arm 2.1. At the free end of the arm 2.1 a print head 3 is attached, which can be moved in all three spatial dimensions by the arm 2.1. The print head 3 can thus be moved to any position in the working area of the

Moving device 2 are moved.

The print head 3 has in the interior one from the end face facing the arm 2.1 (top in FIG. 1) to the opposite and free end face

continuous tubular passage 3.1 for the passage of a water-containing mineral binder composition. At the free end, the passage 3.1 opens into a controllable outlet 4 in the form of a nozzle which

can be opened and closed continuously.

An inlet nozzle 5 for adding an additive opens laterally into the passage 3.1 in an area facing the arm 2.1. Through the inlet nozzle 5, the water-containing mineral binder composition moving through the passage 3.1 can, if required, be given an additive, for example a

Rheological aid, are added. In the interior of the print head 3 with respect to the inlet nozzle downstream, a static mixer 6 is furthermore arranged in the passage 3.1, which additionally mixes the water-containing mineral binder composition and the additive as it flows through.

In the area of the controllable outlet 4, a measuring unit 8 for determining the pressure in the tubular passage 3.1 is also arranged. A

The sampling rate of the measuring unit 8 is e.g. 10 Hz.

A device 7 for venting the water-containing mineral binder composition is also attached to the print head 3. The device is designed as a vacuum treatment device and makes it possible to reduce the proportion of air in the water-containing mineral binder composition. For this purpose, for example, a section of the wall of the passage 3.1 can be designed as a gas-permeable membrane, so that by applying a negative pressure outside the passage 3.1, air is drawn from the water-containing mineral binder composition.

The system 1 for applying a water-based mineral

The binder composition also has a feed device 9, which on the inlet side corresponds to three containers 11.1, 11.2, 11.3 and a reservoir 11.4. In each of the three containers 11.1, 11.2, 11.3 there is a component of the water-containing mineral binding agent

agent composition. The first component, which is present in the first container 11.1, is a dry mineral binder composition. The second component, which is present in the second container 11.2, consists for example of water. The third component present in the third container 11.3 is e.g. a flow agent in the form of a polycarboxylate ether. In the reservoir 11.4 there is e.g. a rheology aid in the form of modified

Cellulose and / or a microbial polysaccharide.

On the outlet side, the feed device 9 has three separate outlets, each with one of three inlets 10.1, 10.2, 10.3 of a mixing device 10 are connected. The feed device 9 also has individually controllable metering devices (not shown in FIG. 1) so that the individual

Components in the individual containers 11.1, 11.2, 11.3 can be dosed individually into the mixing device 10.

Another outlet of the feed device is connected to the inlet nozzle 5 (not shown in FIG. 1), so that the

Feed device 9 additive can be conveyed from the reservoir 11.4 into the inlet nozzle 5.

The mixing device 10 is designed as a dynamic mixer and, in addition to this, comprises an integrated conveying device in the form of a screw conveyor. In the mixing device, the individually metered components are mixed with one another and conveyed into the flexible line 12 attached to the mixing device on the outlet side. During operation, the mixing and conveying of the binder composition can take place continuously.

About the flexible line 12, which with the arm 2.1 facing

The front side of the print head opens into the tubular passage 3.1, the water-containing mineral binder composition can be conveyed into the print head 3 and applied continuously through the controllable outlet 4.

Also part of the system 1 is a measuring unit 13 which is integrated in the conveying line 12 in the area between the mixing device 10 and the print head 3. The measuring unit includes, for example, one

Ultrasonic transducer, which is designed to determine the flow properties of the water-containing mineral binder composition. A sampling rate of the measuring unit 13 is e.g. 10 Hz.

A central control unit 14 of the system 1 comprises a processor, a memory unit and several interfaces for receiving data and several interfaces for controlling individual components of the system 1. The mixing device 10 is connected to the control unit 14 via a first control line 15a, while the feed device is connected to the control unit 14 via a second control line 15b. As a result, the individual components in the containers 11.1, 11.2, 11.3 can be metered into the mixing device 10 via the central control unit according to prescribed recipes stored in the control unit and conveyed into the flexible line 12 at adjustable delivery rates.

The controllable outlet 4, the inlet nozzle 5, and the device 7 for

Ventilation of the water-containing mineral binder composition on the print head are each also connected to the control unit 14 via a separate control line 15c, 15d, 15e and can be controlled or monitored by this.

The movement device 2 is also connected to the control unit 14 via a further control line 15g. The movement of the print head 3 can thus be controlled via the control unit 14.

The measuring unit 8 is connected to the control unit 14 by a data line 15h, so that pressure data recorded in the measuring unit can be transmitted to the control unit 14.

Analogously, the measuring unit 13 is connected to the control unit 14 with a data line 15f, so that data recorded in the measuring unit which contain the

Characterize flow properties, can be transmitted to the control unit 14.

The control unit 14 is programmed, for example, so that:

(i) the rates of addition of the three components of the water-containing mineral binder composition with the feed device 9 as a function of the flow properties of the water-containing composition determined via the measuring unit 13 mineral binder composition can be controlled in the flexible pipe;

(ii) the conveying device integrated in the mixing device 10 is controlled as a function of the pressure 8 determined by the measuring unit 8 and the structure of the object to be produced with the water-containing mineral binder composition;

(iii) the rate of addition of the additive via the inlet nozzle 5 as a function of the flow properties of the water-containing mineral binder composition determined via the measuring unit 13 and the structure of the to

object being created is controlled;

(iv) the degree of ventilation of the hardenable building material in the device 7 is controlled as a function of the flow properties of the water-containing mineral binder composition determined by the measuring unit 13;

(v) the movement device 2 and thus the position of the print head 3 is controlled as a function of a model of the object to be generated stored in the data memory of the control unit 14.

example 1

The dry mineral binder composition according to the invention has the composition described in Table 1.

Table 1 :

Materials used Aluminum sulfate is Al2 (S04) 3 18 H2O, available from Merck, Switzerland.

Betoflow ^® D is a fine calcium carbonate powder of around 1 -5 pm

Particle size, available from Omya.

Nekafill ^® 15 is a limestone powder, available from Kalkfabrik Netstal.

Sika ^® ViscoCrete ^® -225P is a powdery superplasticizer based on a polycarboxylate ether, available from Sika.

Carbowet ^® 4000 is a defoamer, available from Air Products Chemicals Europe.

Denka CSA # 20 is a calcium sulfoaluminate cement based shrinkage reducer, available from Newchem, Switzerland.

The 3D printing was carried out with a system as shown by way of example in FIG. 1.

The dry binder composition with the composition shown in Table 1 was continuously with such an amount of water in the Mixer mixed to obtain a weight ratio of water to dry binder composition of about 0.16. The water-containing mineral binder mixture was then mixed with the in the

Mixing device integrated screw conveyor conveyed via the flexible conveying line to the print head of the 3D printer.

The promotion of the dry binder composition, the addition of the water, the mixing with the water, the promotion of the hydrous

Binder composition and the movement of the print head were controlled by a control unit.

The temperature of the mixing water and that of the ambient air was around 25 ° C.

The binder composition was applied with the printhead to a sheet of plastic laid out on a concrete floor in layers about 30 mm wide and 10 mm fleas. The horizontal speed of the print head was about 40 mm per second. A pipe with a diameter of about 0.6 m and a fleas of 2 meters was made in several vertical layers. The molding was completed after about 2 hours and 40 minutes. The fleas of the lower layers and the upper layers differed no more than 5%. The printed molding had a wavy, very uniform surface with no visible defects. Even after 3 days of storage at 25 ° C. and about 40% relative humidity, the molded article showed no visible cracks.

About 16 hours after the last layer had been applied, the flea body was lifted onto a transport pallet with the aid of carrying straps and a crane without causing any damage to the printed molding.

After about four days the molding was destroyed with the aid of a heavy flame and the fragments were optically analyzed. The fracture surfaces had a uniform surface, without air inclusions or defects. The

Fracture surfaces showed no preferred orientation, that is, the

applied layers showed the same good bond with one another as within the same layer. To determine the strength of the mortar, prisms measuring 40 x 40 x 160 mm were produced and tested in accordance with DIN EN 196-1. The compressive strength of the mortar after 28 days of storage at 20 ° C and 95% rel. Air humidity was 50.2 MPa, the flexural strength was 8 MPa.

Example 2

For example 2, experiments as described in example 1 were carried out.

However, in the formulation of Table 1, the amount of Denka CSA # 20 as indicated in Table 2 was adjusted in each case. The start and end of solidification were determined in accordance with DIN EN 196-3. In addition, the linear decrease in volume within 16 h after mixing with water in

Determined based on EN 12617-4. The following table 2 gives an overview of the results.

Table 2: Formulations and results of Example 2

^{* 1} % by weight in the binder composition of Table 1

Comparative example 1

Example 1 was repeated while maintaining the printing parameters, but the binder composition did not contain any aluminum sulfate. Even before a pressure height of 0.3 m was reached, the structure collapsed.

Comparative example 2

A fresh mortar on 120 kg cement CEM I 52.5, 92 kg of quartz sand of 0-1 mm, 33 kg Betoflow ^® -D 80 kg Nekafill ^® 15, 0.6 kg Sika ^® ^® ViscoCrete -225P, 0004 kg Carbowet® 4000, 0.3 kg superabsorbent and 56.8 kg of water was prepared in a compulsory mixer.

The application by means of a 3D printer was carried out as described in Example 1. The mortar flowed out of the discharge nozzle and could not be applied in layers. The attempt was then canceled.

In Fig. 2 the strength development of mortars over time is shown schematically immediately after mixing with water for up to several hours:

solid line: typical strength development of a mortar as in

Example 1 described;

dotted line: typical strength development of a mortar as in

Comparative Example 1 described;

broken line: typical strength development of a mortar as in

Comparative Example 2 described.

The embodiments described above are to be understood only as illustrative examples, which can be modified as desired within the scope of the invention.

For example, the static mixer 6 can be omitted, so that there is neither a static nor a dynamic mixer in the print head.

In addition to or instead of those integrated in the mixing device 10

Conveying device, one or more further conveying devices can be provided in the conveying line 12 and / or in the print head 3. This can also involve other conveying devices than screw conveyors.

It is also possible in the area of the print head 3 and / or in the

Delivery line 12 instead of or in addition to the measuring unit 8, 13 others

To provide measuring unit, which e.g. enable temperature measurement.

It is also conceivable to completely place the measuring unit 13 in the delivery line

to be omitted or to be integrated in the printhead.

The mixing device 10 can also have fewer or more inlets, so that additional components that are present in additional containers can be metered in. Instead of one or more of the containers 11.1, 112, 11.3, connections to external sources, for example to a water connection, can also be provided.

It is also possible to program the control unit differently, for example so that a volume flow through the delivery line 12 and / or the print head 3 is taken into account.

List of reference symbols

1 system

2 movement device

2.1 movable arm

3 printhead

3.1 Passage

4 controllable outlet

5 inlet nozzle

6 static mixer

7 ventilation device

8 pressure measuring unit

9 feeding device

10 mixing device

10.1 first admission

10.2 second entry

10.3 third entry

11.1 first container

11.2 second container

11.3 third container

11.4 reservoir

12 flexible line

13 Measuring unit with ultrasonic transducer

14 control unit

15a..h control and data lines

Claims

Patent claims:

1. Dry mineral binder composition comprising cement and mineral fillers for the production of molded articles by means of 3D printing, characterized in that the binder composition also comprises at least one accelerator based on aluminum sulfate, at least one superplasticizer based on a polycarboxylate ether and at least one rheological aid, the polycarboxylate ether has at least 1 mmol, in particular at least 1.2 mmol, in particular at least 1.8 mmol, carboxylic acid groups per gram of dry polycarboxylate ether.

2. Binder composition according to claim 1, characterized in that the accelerator based on aluminum sulfate in 0.1 to 2% by weight, preferably in 0.3 to 1.5% by weight, in particular in 0.4 to 1.0% by weight, based on the total weight of the dry

Binder composition, is present.

3. Binder composition according to one of the preceding claims, characterized in that the polycarboxylate ether in 0.02 to 5% by weight, preferably in 0.05 to 4% by weight, in particular in 0.1 to 3% by weight, calculated as dry polymer based on the total weight of the dry binder composition.

4. Binder composition according to one of the preceding claims, characterized in that the rheological aid is selected from the group consisting of modified starches, modified celluloses, microbial polysaccharides, superabsorbents and mineral ones

Thickeners.

5. Binder composition according to one of the preceding claims, characterized in that at least two, preferably at least three different rheological aids in the dry

Binder composition are present.

6. Binder composition according to one of the preceding claims, characterized in that 0.1 to 5% by weight, preferably 0.1 to 4.5% by weight, more preferably 0.5 to 3% by weight, calcium sulfoaluminate, based on the total weight of the dry binder composition, are present .

7. Binder composition according to one of the preceding claims, characterized in that at least one defoamer,

in particular selected from the group consisting of oil-based

Defoamers, silicone-based defoamers, alkyl esters of phosphorus or phosphonic acid, alkoxylated polyols, fatty acid-based

Defoamers, alkoxylated fatty alcohols, and mixtures thereof.

8. Binder composition according to one of the preceding claims comprising:

- 10 to 50% by weight of cement, in particular Portland cement,

- 0.1 to 5% by weight, preferably 0.1 to 4.5% by weight, more preferably 0.5 to 3% by weight, calcium sulfoaluminate,

- 0 to 10% by weight of at least one latent hydraulic binder, in particular metakaolin and / or silica dust,

- 45 to 85% by weight mineral fillers,

- 0.1 to 2% by weight of an accelerator based on aluminum sulfate,

- 0.02 to 5% by weight of at least one polycarboxylate ether,

- 0.01 to 2% by weight of at least one rheological aid,

- 0.01 to 1% by weight of at least one defoamer and

- 0 to 10% by weight further additives,

based on the total weight of the dry binder composition.

9. Aqueous mineral binder composition obtained by blending the dry mineral binder composition according to one of the preceding claims with water, wherein the

Mixing takes place in particular in a continuous mixer.

10. Use of the water-containing mineral binder composition according to claim 9 for the production of moldings by means of 3D printing.

11. A method for applying a mineral binder composition, in particular by means of 3D printing, comprising the steps:

- providing a dry mineral binder composition according to any one of claims 1 to 8, water and optionally at least one further additive;

- adding the dry mineral binder composition,

Water and the optionally at least one further additive in a mixing device (10), in particular in a mixing chamber of the

Mixing device, with a feed device (9);

- Mixing the dry mineral binder composition with water and the optionally at least one further additive in the mixing device (10) to obtain a water-containing mineral binder composition;

- Feeding the water-containing mineral binder composition through a delivery line (12) to a print head (3) movable in at least one spatial direction using a delivery device;

- Applying the water-based mineral

Binder composition with the movable print head (3).

12. The method according to claim 11, characterized in that

- at least one other additive of the dry mineral

Binder composition is added together with the water, the at least one further additive being a further

Polycarboxylate ether, a retarder and / or another

Rheology aid, in particular a polycarboxylate ether, comprises, and

- The metering of the at least one further additive in

Dependent on printing conditions such as horizontal and vertical Print speed, print height and ambient temperature.

13. The method according to any one of claims 11 or 12, characterized in that the speed of the horizontal movement of the print head when applying the water-containing mineral binder composition is at least 20 mm per second, preferably at least 30 mm per second, in particular at least 40 mm per second.

14. Shaped body made by mixing a dry mineral

Binder composition according to at least one of claims 1 to 8 with water and optionally further additives, application of the water-containing mineral binder composition in layers with a 3D printer and hardening of the binder composition.

15. Shaped body according to claim 14, characterized in that it has a height of at least 0.5 m, more preferably at least 1 m, especially at least 1.5 m or 2 m, the height being the sum of all thicknesses applied in the vertical direction Layers results.