EP2205539A1

EP2205539A1 - Powdered additive and method for the production thereof

Info

Publication number: EP2205539A1
Application number: EP08839614A
Authority: EP
Inventors: Urs Mäder; Norman Blank
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2007-10-19
Filing date: 2008-10-17
Publication date: 2010-07-14
Also published as: EP2050729A1; WO2009050255A1; WO2009050255A9

Abstract

The invention relates to a powdered additive (1) particularly for hydraulic binding agents, the powdered particles (1) of the additive comprising an inner layer (2) and an outer layer (3) made of a material acting as an additive.

Description

Powdered additive and process for its preparation

Technical area

The invention is based on a powdery additive according to the preamble of the first claim.

The invention is also based on a process for the preparation of a powdery additive according to the preamble of the method claim.

State of the art

Admixtures have long been known and can have various functions such as air entrainers, retarders, accelerators, stabilizers, chromate reducers, Einpresshilfen, foaming agents, sealants, recycling aids, liquefiers and flow agents. These additives can be used liquid or dried as a powder and are used in particular in hydraulic binders.

Polycondensates such as sulfonated naphthalene condensates, sulfonated melamine condensates, lignin sulfonates are used as plasticizers to improve the processability and the time-dependent flow behavior of hydraulic binders such as cement, mortar, gypsum and concrete. These water-reducing agents are capable of improving the flowability of such blends, but such flowability can not normally be maintained for a sufficiently long period of time. When As a result, additional amounts of water-reducing agents must be added at certain intervals. However, this multiple dosing is not desirable because it is technically difficult to perform.

EP 0 845 444 A1 discloses a concrete additive which comprises a mixture of a lignosulfonate and a water-soluble copolymer of vinyl acetate and an N-substituted maleamic acid and which serves as superplasticizer. The mixture of lignin sulfonate and copolymer to prevent the lignin sulfonate must be added at several intervals. This approach gives good results, but the consumption of the components is relatively high.

Polyalkylene glycol carboxylates, in the following polycarboxylates, have been used for some years as dispersants for aqueous dispersions. They dramatically reduce the water content of these dispersions, especially in hydraulic binder systems. Originally, these polymers were prepared in aqueous solution and used as aqueous polymer solutions. The disadvantage of these solutions, however, are high transport costs, since a high proportion of solvent must be transported, further it can lead to bacterial attack, resulting in a limited shelf life.

Therefore, polycarboxylates are used as powders, either by drying the polycarboxylates present in aqueous solution or by the preparation of solid polycarboxylates, for example from WO 03/080714 A1. Such powders, or solids, have the technical advantage over aqueous solutions that significantly lower costs are incurred during transport, the storage stability is significantly higher because of lower biological infestation or lower cleavage of possible ester bonds in the modified polycarboxylates and the sensitivity to frost is significantly reduced. Such polycarboxylates show in many respects the better properties than previous liquefiers. However, since these polycarboxylates can be relatively expensive, attempts are made to admit as little as possible of them. Likewise, not all required properties of only a polycarboxylate or mixtures thereof, so that other suitable liquefier must be used

Presentation of the invention

The invention has for its object to provide an additive in a powdery additive of the type mentioned above, which avoids the disadvantages mentioned above, i. to provide an inexpensive additive, which is not in several

Intervals must be added and combines the benefits of different chemical modes of action.

According to the invention this is achieved by the features of the first claim.

The core of the invention is therefore that the powdery particles of the additive have one or more inner layer (s) and an outer layer of a material which acts as an additive.

The advantages of the invention can be seen, inter alia, in the fact that no multiple dosing has to be performed by the two-layered or multi-layered structure. In the outer layer can be cheaper

Condenser can be used, through which the basic liquefaction is achieved. This is preferably absorbed faster than the inner layer (s). The outer layer dissolves first and gives a first liquefaction until homogeneous mixture. The active sites of the hydraulic binder, the cement grain, are saturated. This requires less of the inner layer and thus increases the efficiency of the inner layer. If the inner layer is a more expensive condenser, much cheaper additives can be produced over the conventional method. Continue by achieved a better distribution of the condenser in the hydraulic binder and there are no local overdoses, also by a time delay of the mode of action can be achieved.

It is also useful to achieve different effects by means of various additives. In particular, air entrainers, retarders, accelerators, stabilizers, chromate reducers, injection aids, foaming agents, sealants, recycling aids as inner layer or inner layers of the multilayer powder can thus be introduced into the hydraulic binder.

Further advantageous embodiments of the invention will become apparent from the dependent claims.

Short description of the drawing

In the following embodiments of the invention will be explained in more detail with reference to the drawings. The same elements are provided in the various figures with the same reference numerals.

Show it:

1 shows a cross section through an inventive additive.

Fig. 2 shows schematically the dissolution rate of the admixture of Fig. 1;

3 shows a cross section through a further additive according to the invention;

4 shows schematically the dissolution rate of the additive according to FIG. 3.

Only the elements essential for the immediate understanding of the invention are shown. Ways to carry out the invention

In the present invention, an additive is prepared having at least two layers of condensers. In Fig. 1, such an additive 1, which has two layers, is shown schematically. It has at least one inner layer with a first one

Condenser 2 and an outer layer with a second condenser 3 on. When dissolving this two-layer additive 1, the outer second condenser 3 and then the inner first condenser 2 are dissolved according to the dissolution diagram in Fig. 2, first. In a transitional area, both condensers can be released together.

It goes without saying that the layers shown in Fig. 1 and the other figures show only a schematic representation. The thickness and shape of the layers is arbitrary and in particular the thickness is adapted to the corresponding amount of material to be dispensed. In addition, the layers need not be closed, so that in part the inner layers can lie directly on the surface.

As the plasticizer and plasticizer for hydraulic binders such as concrete, mortar and gypsum, for example, naphthalene sulfonate, lignin sulfonate, melamine sulfonate, polycarboxylates, polyacrylates, etc. may be used.

Naphthalene sulfonate has the variants sodium naphthalene sulfonate, calcium naphthalene sulfonate and causes very good liquefaction and gives high early strength. Such products are known to the person skilled in the art and are described, for example, in US Pat. No. 3,537,869 and EP 0 214 412 A1. Lignosulfonate is a waste product of the cellulose industry, variants are sodium lignosulfonate, calcium lignin sulfonate, magnesium lignosulfonate. Lignosulfonate is made from cellulose by hydrolysis and sulfonation. Lignosulfonate causes a good liquefaction at low dosage, the residual sugar may have a retarding effect. Such products are known in the art and described for example in DE 32 04 326 A1.

Melamine sulphonate also has a very good liquefaction. Such products are known to the person skilled in the art and are described, for example, in DE 1 671 017 OS.

Particularly preferred high-performance plasticizers and flow agents consist of polycarboxylates. Polycarboxylates are comb polymers which consist of a main chain to which carboxylic acid groups are bonded as free acids or in the form of their salts, and side chains of polyalkylene oxide. Such polycarboxylates are known per se, for example from EP 1 136 508 A1, EP 1 138 696 A1 and EP 1 138 697 A1 of the Applicant. The disclosure of these polycarboxylates is included below. Such polycarboxylates are sold under the name ViscoCrete ^®. The polyalkylene oxide or polyalkylene glycol side chains may be attached to the backbone via ester linkage, amide linkage or ether linkage. In addition to the carboxylic acid groups and the polyalkylene oxide side chains, other functional or non-functional groups may be attached to the main chain.

Such comb polymers can be prepared for example by Copolymehsation of unsaturated mono- or di-carboxylic acids with unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, allyl ethers or vinyl ethers. The carboxylic acids in the finished comb polymer can be present in the form of their free acid or completely or partially in the form of their salts.

The comb polymers can also be prepared by polymer-analogous reactions. In this case, a polymer which is latent or free Carboxyl groups containing one or more compounds which contain amine or hydroxyl functions are reacted under conditions which lead to partial amidation or esterification of the carboxyl groups. The polyalkylene glycol of the side chain is based on polymerized epoxide-containing compounds, such as ethylene oxide, propylene oxide, 1-butene oxide, phenylethylene oxide, etc. Preferably, the polyether side chain thus consists of polyethylene oxide or polypropylene oxide or a mixed copolymer of ethylene oxide and propylene oxide and has at the free end a hydroxyl group, a primary amino group or an alkyl group having 1 to 20 carbon atoms which is linear, branched or cyclic, preferably a linear alkyl group having 1 to 4 carbon atoms. These polycarboxylates have a molecular weight of 50,000 to 200,000, preferably 8,000 to 100,000, particularly preferably a molecular weight of 10,000 to 80,000. The Cabonsäuresalze can alkali metal or alkaline earth metal salts or salts of other di- or trivalent metal ions,

Ammonium ions, organic ammonium groups or mixtures.

In one embodiment, the polycarboxylate according to the invention consists of four structural units (a, b, c and d) and has the structural formula A.

-f L ^cH 2- IH Yes L ^cH 2 ^~ s IH Jb L ^CH 2- ^c I III

M _R 1 _R 2

in which:

M = hydrogen, alkali metal ion, alkaline earth metal ion, di- or trivalent metal ion, ammonium ion, organic ammonium group or mixtures thereof, R = each R independently of the other hydrogen or methyl, R ¹ and R ² = C ¹ to C ₂₀ alkyl, cycloalkyl, or alkylaryl,

- [AO] _n -FM, where A = C ₂ to C ₄ alkylene, R ₄ = C ₁ to C ₂₀ alkyl, cyclohexyl, or alkylaryl, and n = 2 - 250, preferably n = 8 - 200, more preferably n = 11 - 150, in particular n = 11 -100,

R ³ = -NH ₂ , -NR ⁵ R ⁶ , -OR ⁷ NR ⁸ R ⁹ , wherein R ⁵ and R ^{6 are} independently a Ci to C ₂ o alkyl, cycloalkyl-I or alkylaryl or aryl group or a hydroxyalkyl group , such as hydroxyethyl, hydroxypropyl, hydroxybutyl, or a

Acetoxyethyl (CH ₃ -CO-O-CH ₂ -CH ₂ -),

Hydroxy-isopropyl- (HO-CH (CHs) -CH ₂ -),

Acetoxyisopropyl group (CH ₃ -CO-O-CH (CH ₃ ) -CH ₂ -), or R ⁵ and R ⁶ together form a ring, of which the nitrogen is a part, to form a morpholine or imidazoline ring, wherein R ⁷ a C 2 -C 4 -alkylene group and R ⁸ and R ⁹ independently of one another a C 1 -C ₂₀ -alkyl-, cycloalkyl-,

Alkylaryl or aryl group or a hydroxyalkyl group such as

Hydroxyethyl, hydroxypropyl or hydroxybutyl group

a / b / c / d = (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.8) / (0 - 0.3), preferably (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.5) / (0 - 0.1), more preferably (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.3) / (0 - 0.06), even more preferably (0.2 - 0.8) / (0.199 - 0.799) / (0.001 - 0.09) / (0 - 0.06), more preferably (0.2 - 0.8) / (0.19 - 0.79) / (0 - 0.1) / (0.01 - 0.3), and a + b + c + d = 1.

The sequence of building blocks a, b, c, d can be block-wise, alternating or random. Polycarboxylates according to the formula A can be imagined to be composed of a main chain of polymerized units of acrylic acid and

Methacrylic acid or a mixed copolymer thereof. The polyalkylanoxide Side chains are linked to this backbone via ester or amide groups.

In addition to the carboxylic acid groups or the carboxylic acid salts and the polyalkylene glycol side chains, further groups may be bonded via the ester or amide bond on the main chain of the polycarboxylates, for example alkyl groups, cycloalkyl groups, aromatics, substituted aromatics, hydroxyalkyl groups, dialkylaminoalkyl groups or heterocyclic rings in which the N of the amide group is an ingredient, such as morpholine or imidazole. Examples of groups R ³ which are bonded via their N as amides to the main chain are amine radicals which have one or two independent aliphatic, cycloaliphatic or aromatic radicals of 1 to 20 carbon atoms, such as, for example, methyl, ethyl, propyl, isobutyl. Propyl, - butyl, iso-butyl or cyclohexyl radicals. Examples of such amine radicals are dibutylamine or dicyclohexylamine. Further examples are amine radicals with hydroxyalkyl groups such as ethanolamine or diethanolamine. Examples of groups R ³ attached via their O as esters to the main chain are aliphatic, cycloaliphatic or aromatic radicals of 1 to 20 carbon atoms, such as methyl, ethyl, propyl, iso-propyl, butyl, iso Butyl or cyclohexyl radicals. Further examples are aminoalcohol radicals such as methyldiethanolamine, triisopropanolamine, triethanolamine, dibutylaminoethanol, diisopropanolamine, diethylaminoethanol, dimethylaminoethanol.

The first and second condenser may be of different categories such as polycarboxylate and lignin sulfonate or of the same category, i. For example, consist of polycarboxylates of different types.

Particular preference is given to polycarboxylate as the first plasticizer in the inner layer and naphthalene sulfonate, lignin sulfonate or melamine sulfonate as second plasticizer in the outer layer Lignosulfonate, used. The sulphonated condenser achieves the basic liquefaction. For example, the lignin sulfonate absorbs faster than the polycarboxylate. The lignosulfonate first dissolves and gives a first liquefaction until homogeneous mixing and the active sites of the cement grain are saturated. This will be less

Polycarboxylate needed and thus increases the efficiency of Polycarboxylat.es. Furthermore, a better distribution of the liquefier in the hydraulic binder is achieved, and there are no local overdoses.

In Fig. 3, a further additive with additional layers is shown schematically. It has an outer layer with a second condenser 3, followed by a second intermediate layer 6, followed by the first condenser 2, then a first intermediate layer 5 and completely inside a further layer 4, in the following innermost layer or core called. Upon dissolution of this multi-layered additive 1, according to the dissolution diagram in Fig. 4, first the outer layer, i. the second condenser 3, then the second intermediate layer 6, then the inner layer, i. the first condenser 2, then the first intermediate layer 5 and optionally, shown in phantom, the innermost layer 4 dissolved. In the

Transition areas can each be released two consecutive layers with each other.

Not shown is that the first intermediate layer 5 and / or the second intermediate layer 6 and / or the innermost layer 4 can be omitted, or even further layers can be additionally arranged.

The additional intermediate layers and the innermost layer can consist of any materials. Particularly preferred are additives such as air entraining agents, retarders, accelerators, stabilizers, chromate reducers, injection aids, foaming agents, sealants, recycling aids and of course plasticizers and flow agents or mixtures of the aforementioned additives. The intermediate layers and the innermost layer can also be made of any other materials, such as polyvinyl alcohol PVA.

The intermediate layer serves on the one hand to control the delivery and dissolution of the condenser layers and on the other hand to deliver additional additives in the hydraulic binder. For example, the arrangement of PVA as layer 6 between polycarboxylate as the first condenser layer 2 and lignin sulfonate as the second condenser layer 3 delays the release of the polycarboxylate.

As the innermost layer 4, any material can be used. These may be the above-mentioned materials or in principle all substances used for the production of the concrete, in particular cement particles. It is also possible to use substances or additives, such as, for example, silica fume, fly ash, light aggregate, slag, fiber materials, e.g. organic such as polypropylene fibers, etc. or inorganic such as basalt, glass, etc. may be used. For example, fly ash of different origin has different adsorption properties and thus has different properties depending on the origin in the concrete. Coating with additives results in identical and more adapted properties, so that the different origin no longer has to be considered.

However, a mineral carrier material as described in WO 00/47533 A1 can also be used as the innermost layer. These support materials can be coated according to the disclosure of WO 00/47533 A1 with a first layer of polycarboxylate and give a free-flowing powder. This is then provided according to the invention with further layers.

The methods used to construct the layers are known to the person skilled in the art. Such coating methods are described, for example, in WO2006 / 027363 A1, the disclosure of which is hereby incorporated by reference is. The coating can be done for example in a DC mixer, a countercurrent mixer or a fluidized bed mixer with rotary atomizer.

Examples of production:

The coated particulate additives according to the invention are prepared, for example, by treating a powdery innermost layer with the coating substances, which as a rule consist of an aqueous solution or suspension of the constituents of this coating substance, and then drying. In this case, it is possible, for example, to mix the innermost layer with the aqueous coating substance in a mixer and then to dry the particles thus treated, or it is likewise possible to spray the aqueous coating agent onto the particles in a fluidized-bed dryer through which hot air flows, drying at the same time.

To produce the coated particles according to the invention in a fluidized bed, the innermost layers, ie cores, in the fluidized bed are sprayed with the coating material while maintaining a fluidized bed temperature of 30 to 100 ^° C. and dried simultaneously or subsequently. If several layers are applied, the aqueous solutions or dispersions of the coating materials are sprayed one after the other.

Of course, the invention is not limited to the embodiment shown and described. LIST OF REFERENCE NUMBERS

1 additive

2 inner layer / first condenser

3 outer layer / second condenser

4 innermost layer

5 first intermediate layer 6 second intermediate layer

T time

Claims

claims

1. powdery additive (1) in particular for hydraulic binders, characterized in that the powdery particles (1) of the additive have an inner layer (2) and an outer layer (3) of a material which acts as an additive.

2. additive according to claim 1, characterized in that the powdery particles of the additive further layers

(5, 6) and / or an innermost layer (4) of a material which acts as an additive.

3. Additive according to one of claims 1 or 2, characterized in that the layers (2, 3, 5, 6) or the innermost layer (4) consist of a condenser and the additive serves as a dispersion aid.

4. additive according to claim 3, characterized in that the acting as a condenser layers of naphthalenesulfonate,

Lignosulfonate, melamine sulfonate, polycarboxylate and / or polyacrylate exist.

5. Additive according to one of the preceding claims, characterized the further layers (5, 6) or the innermost layer (4) consist of air entrainers, retarders, accelerators, stabilizers, chromate reducers, injection aids, foaming agents, sealants, recycling aids, polyvinyl alcohol or mixtures of the aforementioned additives.

6. additive according to claim 5, characterized in that the innermost layer (4) of cement, silica, fly ash, light aggregate, slag, organic or inorganic

Fiber materials, mineral carrier material.

7. Additive according to one of the preceding claims, characterized in that at least one inner layer of the powdered particles of the

Additive consists of polycarboxylate.

8. Additive according to one of the preceding claims, characterized in that at least one outer layer of the powdered particles of

Addition of naphthalenesulfonate, lignin sulfonate and / or melamine sulfonate.

9. A process for the preparation of a powdery additive (1) in particular for hydraulic binders, characterized in that an inner layer (2) made of a material which acts as an additive, and in that an outer layer (3) of a material than

Additive acts on the inner layer is applied.

10. The method according to claim 9, characterized in that between the inner layer (2) and the outer layer (3), a further layer (6) is applied.

11. The method according to claim 9 or 10, characterized in that the inner layer (2) on a further layer (5) or an innermost layer (4) is applied.

12. The method according to any one of claims 9 to 11, characterized in that the further layers (2, 3, 5, 6) or the innermost layer (4) consist of a condenser.

13. The method according to any one of claims 9 to 12, characterized in that the further layers (5, 6) or the innermost layer (4) of air entrainers, retarders, accelerators, stabilizers, chromate reducers, Einpresshilfen, foaming agents, sealants, recycling aids, polyvinyl alcohol or mixtures of the aforementioned

Additives exist.

14. The method according to any one of claims 9 to 13, characterized in that the innermost layer (4) of cement, Silikafume, fly ash,

Slight aggregate, slag, organic or inorganic fiber materials, mineral carrier material.

15. The method according to any one of claims 9 to 14, characterized in that at least one inner layer of the powder particles of the additive consists of polycarboxylate, and / or in that at least one outer layer of the powdery particles of the additive consists of naphthalene sulfonate, lignin sulfonate and / or melamine sulfonate.