Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B14/02—Granular materials, e.g. microballoons
  • C04B14/30—Oxides other than silica
  • C04B14/305—Titanium oxide, e.g. titanates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
  • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
  • C04B40/0039—Premixtures of ingredients

Definitions

• Dispersion comprising titanium dioxide and polycarboxylate ether
• the invention relates to a concrete additive based on titanium dioxide and polycarboxylate ether.
• WO 01/90024 discloses a concrete composition which contains aggregates, a hydraulic binder, silica sol and a polycarboxylate.
• the BET surface area of the silica sol is preferably 300 to 900 m 2 /g.
• Silica sols are individual particles having a diameter of 3 to 50 nm and are only stable in dispersion. In cement or concrete compositions they have a high reactivity, but no filler effect. This is probably to be attributed to the fact that on account of the very low particle diameter of the silica sols these can rapidly dissolve in an alkaline medium. In order to be able to observe a high early strength when using silica sols, high concentrations of silica sols are necessary, which leads to a marked reduction of the workability.
• a composite material which contains inorganic aggregates, ultrafine particles, a cement-containing binder and a concrete superplasticizer .
• the composite material allows the production of highly plasticized concrete, in which no bleeding occurs.
• the ultrafine particles employed are mainly "silica fume” particles, which are obtained in connection with the production of silicon metal or ferrosilicon .
• Silica fume” particles as a rule, are present as spherical individual particles having a diameter of 150 nm or more. In cement or concrete compositions, they show a strong filler effect, but are not very reactive here on account of their low specific surface area of about 20 m 2 /g.
• particles of this order of magnitude which can be employed are argillaceous earth, fly ash, natural pozzolana, calcium carbonate, aluminum oxide, barium sulfate and titanium dioxide.
• the particles specified have the disadvantage that they have a small specific surface area, which leads to a low nucleation rate of the strength-forming phases and thus to low early strengths.
• Early strength is understood within the context of the present text as meaning the strength of a concrete after ⁇ 48 h of cement hydration.
• the proportion of the ultrafine particles, based on the total amount of the composite material, is 1 to 30% by weight or about 10 to 25% by weight in the working examples, based on the sum of cement and ultrafine particles. Thus the necessary amount of ultrafine particles is very high.
• a process for the improvement of the early strength is disclosed in which an aqueous dispersion which contains a mineral filler and a special dispersant is added to cement.
• mineral fillers it is possible to employ calcium carbonate, barium carbonate, limestone, dolomite, talc, silicon dioxide, titanium dioxides, kieselguhr, iron oxide, manganese oxide, lime, kaolin, clay, mica, gypsum, fly ash, slag, calcium sulfate, zeolites, basalt, barium sulfate or aluminum trihydroxide .
• calcium carbonate is employed.
• average particle diameters of the mineral fillers employed are in the range from about 2 to about 10 ⁇ m.
• a special dispersant is essential for the invention disclosed in US 6752866.
• No actual details are given for the necessary amounts of mineral filler, dispersant and cement. From the working examples, it is to be inferred that the content of mineral filler is 10% by weight (silicon dioxide, Test number 12) or 30% by weight (silicon dioxide, Test number 17) and the content of dispersant 0.5 (Test number 17) or 0.75% by weight (Test number 12), based on silicon dioxide. On account of the large particle diameter, these dispersions show only a low stability to sedimentation.
• EP-A-I 607378 for cement-containing systems additives based on pyrogenic metal oxides are described which contain at least one sorbent.
• the pyrogenic metal oxides can be present in the form of aqueous dispersions.
• a superplasticizer based on polycarboxylate can be employed.
• the technical teaching must be inferred that the disclosed metal oxide powders silicon dioxide, aluminum oxide, titanium dioxide, cerium oxide, zirconium oxide and mixtures thereof show an essentially similar action.
• the prior art shows that there is a lively interest in developing concrete compositions which have a high early strength with, at the same time, good workability.
• the prior art further shows that the presently available superplasticizers and particles in the cement or concrete composition are a sensitive system. For example, the sequence of the addition and the concentration of the substances used have a crucial influence on the workability processability and the early strength of the concrete.
• the object of the invention to make available a concrete additive with which the disadvantages of the prior art can be minimized.
• the concrete additive should markedly increase the early strength of concretes with, at the same time, good workability.
• the invention relates to a dispersion which is free of binders and which contains titanium dioxide and at least one water-soluble polycarboxylate ether, where
• the titanium dioxide has a BET surface area of 20 to 400 m 2 /g
• the water-soluble polycarboxylate ether is a copolymer based on at least one oxyalkylene glycol compound and at least one unsaturated monocarboxylic acid derivative or dicarboxylic acid derivative,
• the dispersion has a content of titanium dioxide of 5 to 50% by weight, based on the total amount of the dispersion .
• titanium dioxide and titanium dioxide particles designate the same substance.
• the dispersion according to the invention is preferably an aqueous dispersion, that is the main constituent of the liquid phase is water.
• the liquid phase moreover contains the water-soluble polycarboxylate ether.
• binders are understood as meaning inorganic substances, such as, for example, cement, or organic substances, which are processable in the plastic state, and harden in the course of a certain time and thereby combine other substances with one another.
• titanium dioxide also comprises metal mixed oxides with titanium dioxide as the first component.
• metal mixed oxides with titanium dioxide as the first component.
• aluminum oxide, potassium oxide, lithium oxide, sodium oxide, magnesium oxide, calcium oxide, silicon dioxide and/or zirconium dioxide can be preferred.
• a mixture of titanium dioxide with the aforementioned mixed oxides is present .
• titanium dioxide is not restricted.
• it can be titanium dioxide which is precipitated or obtained by sol-gel or pyrogenic processes .
• a pyrogenic titanium dioxide is a constituent of the dispersion according to the invention. Pyrogenic is to be understood as meaning titanium dioxide particles obtained by flame oxidation and/or flame hydrolysis.
• Titanium tetrachloride for example, is particularly suitable.
• the titanium dioxide particles thus obtained are to the greatest extent pore- free and have free hydroxyl groups on the surface.
• the pyrogenic titanium dioxide particles within the meaning of the present invention are at least partially present in the form of aggregated primary particles. As a rule, the pyrogenic titanium dioxide particles are to the greatest extent present in aggregated form.
• the pyrogenic titanium dioxide can also be present as a pyrogenic mixed oxide with titanium dioxide as the first component.
• the second and further components in particular aluminum oxide, potassium oxide, lithium oxide, sodium oxide, magnesium oxide, calcium oxide, silicon dioxide and/or zirconium dioxide can be preferred.
• a mixture of pyrogenic titanium dioxide is present with the aforementioned mixed oxides .
• the pyrogenic titanium dioxide according to the invention can also be present in surface-modified form.
• the surface can be surface-modified, for example, with haloorganosilanes, alkoxysilanes, silazanes, siloxanes, polysiloxanes .
• the silanizing agents used can be trimethoxyoctylsilane [(CH 3 O) S -Si-CsHi 7 ], octamethyl- cyclotetrasiloxane or hexamethyldisilazane . Since the stability of the dispersion according to the invention is lower, as a rule, in the case of surface-modified titanium dioxide than in the case of unmodified titanium dioxide, the latter is given precedence.
• the BET surface area of the titanium dioxide present in the dispersion according to the invention is restricted to values of 20 to 400 m 2 /g.
• the BET surface area can preferably be 30 to 150 m 2 /g, values of 40 to 60 m 2 /g or of 80 to 100 m 2 /g being particularly advantageous.
• the dispersion according to the invention has a mean diameter (number-based) of the titanium dioxide particles in the dispersion of preferably less than 1 ⁇ m, particularly preferably of 50 to 500 nm and very particularly preferably of 70 to 300 nm. Values below 50 nm can only be realized technically with difficulty and do not have any more advantages in use.
• the mean diameter is the mean diameter of the individual particles, in the case of aggregated particles the diameter of the aggregates.
• the content of titanium dioxide in the dispersion according to the invention is 5 to 50% by weight, based on the total amount of the dispersion.
• Dispersions according to the invention which have a titanium dioxide content of 10 to 30% by weight as a rule show a better stability than more highly filled dispersions and are therefore preferred. Dispersions containing less than 5% by weight of titanium dioxide are not economical on account of the high water content .
• the weight ratio polycarboxylate ether/titanium dioxide is not limited. As a rule, values in the dispersion according to the invention of 0.01 to 100 are advantageous and values of 0.05 - 5 are particularly advantageous.
• the pH of the dispersion according to the invention can vary within wide limits. As a rule, the pH can be between 2 and 12.
• bases or acids can be added to the dispersion according to the invention.
• bases it is possible to employ, for example, ammonia, ammonium hydroxide, tetramethylammonium hydroxide, primary, secondary or tertiary organic amines, sodium hydroxide solution or potassium hydroxide solution.
• acids it is possible to employ, for example, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid or carboxylic acids.
• the dispersion according to the invention can contain a copolymer having the structural groups a) , b) , c) , preferably having the structural groups a) , b) , c) , and d) .
• the proportion of the structural group a) is 25 to 95 mol%, of the structural group b) 1 to 48.9 mol%, of the structural group c) 0 to 5 mol% and of the structural group d) 0 to 47.9 mol%.
• the proportion of the structural group a) is 51 to 95 mol% and of the structural group c) is 0.1 to 5 mol% .
• the first structural group a) is a mono- or dicarboxylic acid derivative having the general formula Ia, Ib or Ic dar .
• R 1 is hydrogen or an aliphatic hydrocarbon radical having 1 to 20 C atoms, preferably a methyl group.
• X in the structures Ia and Ib is -0M a and/or -0- (C m H 2m O) n -R 2 or -NH- (C m H 2m O) n -R 2 having the following meaning for M, a, m, n and R 2 :
• substituted ammonium groups are preferably employed which are derived from primary, secondary or tertiary Ci-20-alkylamines, Ci-20-alkanolamines, C5-8- cycloalkylamines and Cs-i-j-arylamines .
• Examples of the corresponding amines are methylamine, dimethylamine, trimethylamine, ethanolamine, diethanolamine, triethanol- amine, methyldiethanolamine, cyclohexylamine, dicyclohexyl- amine, phenylamine, diphenylamine in the protonated (ammonium) form.
• the aliphatic hydrocarbons can in this case be linear or branched and saturated or unsaturated.
• Preferred cycloalkyl radicals are to be regarded as cyclopentyl or cyclohexyl radicals, preferred aryl radicals as phenyl or naphthyl radicals, which in particular can also be substituted by hydroxyl, carboxyl or sulfonic acid groups.
• the second structural group b) corresponds to formula II
• R 3 is in turn hydrogen or an aliphatic hydrocarbon radical having 1 to 5 C atoms, which can likewise be linear or branched or alternatively unsaturated, p can assume values between 0 and 3.
• Formula II also comprises compounds shown in formula II A
• R 3 is hydrogen or an aliphatic hydrocarbon radical having 1 to 5 C atoms, p is 0 to 3, R 2 is hydrogen, an aliphatic hydrocarbon radical having 1 to 20 C atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 C atoms, an optionally substituted aryl radical having 6 to 14 C atoms n' is a value from 0 to 190.
• m 2 and/or 3, so that the groups are polyalkylene oxide groups which are derived from polyethylene oxide and/or polypropylene oxide.
• p in formula II is 0 or 1, i.e. they are vinyl and/or alkyl polyalkoxylates .
• the third structural group c) corresponds to the formula IHa or IHb
• S can in this case be -H, -COOM a or -COOR 5 , where a and M have the abovementioned meaning and R 5 can be an aliphatic hydrocarbon radical having 3 to 20 C atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 C atoms or an aryl radical having 6 to 14 C atoms.
• the aliphatic hydrocarbon radical can likewise be linear or branched, saturated or unsaturated.
• the preferred cycloaliphatic hydrocarbon radicals are in turn cyclopentyl or cyclohexyl radicals and the preferred aryl radicals phenyl or naphthyl radicals.
• T -COOR 5
• S COOM a or -COOR 5 .
• the structural groups c) can also have other hydrophobic structural elements. These include the polypropylene oxide or polypropylene oxide-polyethylene oxide derivative where
• x here assumes a value from 1 to 150 and y from 0 to 15.
• R 6 can in this case in turn be R (for meaning of R see above) or
• the polydimethylsiloxane group can not only be bonded directly to the ethylene radical as in formula Ilia, but also via the groups
• R 7 can moreover also be
• the corresponding difunctional ethylene compounds corresponding to the formula Ilia are concerned here, which are linked to one another via the corresponding amide or ester groups and where only one ethylene group has been copolymerized.
• V can be either a polydimethylsiloxane radical W or an -0- CO-C6H4-CO-O- radical and R 2 has the meaning indicated above.
• the fourth structural group d) is derived from an unsaturated dicarboxylic acid derivative of the general formula IVa and/or IVb having the meaning indicated above for a, M, X and Y.
• the copolymers contain 55 to 75 mol% of structural groups of the formula Ia and/or Ib, 19.5 to 39.5 mol% of structural groups of the formula II, 0.5 to 2 mol% of structural groups of the formula Ilia and/or IHb and 5 to 20 mol% of structural groups of the formula IVa and/or IVb.
• the copolymers according to the invention additionally contain up to 50 mol%, in particular up to 20 mol%, based on the sum of the structural groups a to d, of structures which are based, inter alia, on monomers based on vinyl- or (meth) acrylic acid derivatives such as styrene, methylstyrene, vinyl acetate, vinyl propionate, ethylene, propylene, isobutene, hydroxyalkyl (meth) acrylates, acrylamide, methacrylamide, N-vinylpyrrolidone, allylsulfonic acid, methallylsulfonic acid, vinylsulfonic acid, vinylphosphonic acid, AMPS, methyl methacrylate, methyl acrylate, butyl acrylate, allylhexyl acrylate.
• acrylic acid derivatives such as styrene, methylstyrene, vinyl acetate, vinyl propionate, ethylene, propylene, isobutene
• the number of repeating structural units in the copolymers is not restricted. It has proven particularly advantageous, however, to set mean molecular weights of 1000 to 100 000 g/mol .
• the copolymers can be prepared in various ways. It is essential here that 51 to 95 mol% of an unsaturated mono- or dicarboxylic acid derivative, 1 to 48.9 mol% of an oxyalkylene alkenyl ether, 0.1 to 5 mol% of a vinylic polyalkylene glycol, polysiloxane or ester compound and 0 to 55 mol% of a dicarboxylic acid derivative are polymerized with the aid of a free radical starter.
• Unsaturated mono- or dicarboxylic acid derivatives employed which form the structural groups of the formula Ia, Ib or Ic are preferably: acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, itaconic acid imide and itaconic acid monoamide.
• acrylic acid methacrylic acid, itaconic acid and itaconic acid monoamide
• mono- or divalent metal salts preferably sodium, potassium, calcium or ammonium salts
• the preferred substituents on the aryl radical are -OH, -COO- or -SO3- groups.
• the unsaturated monocarboxylic acid derivatives can only be present as monoesters, while in the case of the dicarboxylic acid itaconic acid diester derivatives are also possible.
• the derivatives of the formula Ia, Ib and Ic can also be present as a mixture of esterified and free acids and are used in an amount of preferably 55 to 75 mol%.
• the second component for the preparation of the copolymers according to the invention is an oxyalkylene glycol alkenyl ether, which is preferably employed in an amount of 19.5 to 39.5 mol%.
• oxyalkylene glycol alkenyl ethers corresponding to the formula V
• R 2 , m and n have the meaning already mentioned above.
• the third component employed for the introduction of the structural group c) is preferably 0.5 to 2 mol% of a vinylic polyalkylene glycol, polysiloxane or ester compound.
• Preferred vinylic polyalkylene glycol compounds used are derivatives corresponding to the formula VI,
• R 6 can either in turn be R 1 or
• monomers are maleic acid N- (methylpolypropylene glycol) monoamide, maleic acid N- (methoxypolypropylene glycol-polyethylene glycol) monoamide, polypropylene glycol vinyl ether and polypropylene glycol allyl ether.
• bifunctional vinyl compounds are concerned whose polypropylene glycol- (polyethylene glycol) derivatives are bonded to one another via amide or ether groups (-0- or -OCH 2 -) .
• examples of such compounds are polypropylene glycol bismaleamic acid, polypropylene glycol diacrylamide, polypropylene glycol dimethacrylamide, polypropylene glycol divinyl ether, polypropylene glycol diallyl ether.
• monomers are monovinylpolydimethylsiloxanes .
• suitable derivatives are those corresponding to the formula VIII,
• R 4 S and S is preferably hydrogen.
• Examples of such monomers having a vinyl function are polydimethylsiloxanepropylmaleamic acid or polydimethylsiloxanedipropyleneaminomaleamic acid. If R 7 ⁇ R , they are divinyl compounds such as, for example, polydimethylsiloxane-bis (propylmaleamic acid) or polydimethylsiloxane-bis (dipropyleneaminomaleamic acid) .
• R 7 can be either R 2 or else
• R 7 R 1
• R 7 R 1
• examples of such monovinylic compounds are polydimethylsiloxane- (l-propyl-3- acrylate) or polydimethylsiloxane- (l-propyl-3- methacrylate) .
• R 7 ⁇ R 2 they are divinyl compounds such as, for example, polydimethylsiloxane-bis (l-propyl-3-acrylate) or polydimethylsiloxane-bis (l-propyl-3-methacrylate) .
• ester compounds are di-n-butyl maleate or fumarate or mono-n- butyl maleate or fumarate.
• V can in this case be W (that is a polydimethylsiloxane group) , which corresponds to a dialkenylpolydimethylsiloxane compound such as, for example, divinylpolydimethylsiloxane .
• V can also be -O-CO-C6H4-CO-O-.
• These compounds are dialkenylphthalic acid derivatives.
• a typical example of such phthalic acid derivatives is diallyl phthalate.
• the molecular weights of the compounds which form structural group c) can be varied within wide limits and are preferably between 150 and 10 000.
• the fourth component which can be used for the preparation of the copolymers is preferably 5 to 20 mol% of an unsaturated dicarboxylic acid derivative (XII):
• the unsaturated dicarboxylic acid derivative is derived from maleic acid, fumaric acid, mono- or divalent metals salts of these dicarboxylic acids, such as the sodium, potassium, calcium or ammonium salt or salts with an organic amine radical.
• monomers used which form the unit Ia are polyalkylene glycol monoesters of the abovementioned acids having the general formula XIII:
• the fourth component can also be derived from the unsaturated dicarboxylic acid anhydrides and imides of the general formula XIV (5 to 20 mol%)
• the dispersion according to the invention can furthermore contain a copolymer whose basis is an oxyalkenyl glycol alkenyl ether and the copolymer contains the structural groups a) , b) and c) .
• the content of structural group a) is 10 to 90 mol%, of structural group b) 1 to 89 mol%, of structural group c) 0 to 5 mol% and of structural group d) 0.1 to 10 mol%.
• the first structural group a) is an unsaturated dicarboxylic acid derivative corresponding to the formula IVa or IVb. - CH CH - CH CH
• Organic amine radicals employed are preferably substituted ammonium groups which are derived from primary, secondary or tertiary Ci- to C2o-alkylamines, C x - to C2o-alkanolamines, C 5 - to Cs-cycloalkylamines and C ⁇ to Ci 4 -arylamines .
• corresponding amines are methylamine, dimethyl- amine, trimethylamine, ethanolamine, diethanolamine, tri- ethanolamine, cyclohexylamine, dicyclohexylamine, phenyl- amine, diphenylamine in the protonated (ammonium) form.
• the aliphatic hydrocarbon radicals can in this case be linear or branched and saturated or alternatively unsaturated.
• Preferred cycloalkyl radicals are to be regarded as cyclo- pentyl or cyclohexyl radicals, preferred aryl radicals as phenyl or naphthyl radicals, which can in particular also be substituted by hydroxyl, carboxyl or sulfonic acid groups.
• X can additionally be -NHR and/or -NR 2 2 , which corresponds to the mono- or disubstituted monoamides of the corresponding unsaturated dicarboxylic acid, where R 2 can in turn be identical to R 1 or instead can be -CO-NH 2 .
• R 3 is in turn hydrogen or an aliphatic hydrocarbon radical having 1 to 5 C atoms (which can likewise be linear or branched or alternatively unsaturated) .
• Formula II also comprises compounds shown in formula II A
• R 3 is hydrogen or an aliphatic hydrocarbon radical having 1 to 5 C atoms, p i s 0 to 3 ,
• R 2 is hydrogen, an aliphatic hydrocarbon radical having 1 to 20 C atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 C atoms, an optionally substituted aryl radical having 6 to 14 C atoms n' is a value from 0 to 190.
• the third structural group c) corresponds to the formula IHa or IHb
• S can in this case be -H, COOM a or -COOR 5 , where a and M have the abovementioned meaning and R 5 can be an aliphatic hydrocarbon radical having 3 to 20 C atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 C atoms or an aryl radical having 6 to 14 C atoms.
• the aliphatic hydrocarbon radical can likewise be linear or branched, saturated or unsaturated.
• CH 3 x in this case assumes a value from 1 to 150 and y from 0 to 15.
• R 6 can in this case in turn be R 1 (for meaning of R 1 see above) or
• These compounds are polypropylene oxide (-polyethylene oxide) derivatives of the bifunctional alkenyl compounds corresponding to formula Ilia.
• R 7 R 1 and r can in this case assume values from 2 to 100.
• the proportion of structural groups of the formula Ilia or IHb is 0.1 to 10 mol%.
• the polydimethylsiloxane group W can be bonded not only directly to the ethylene radical as in formula Ilia, but also via the groups
• R 7 can moreover additional ly be
• V can either be a polydimethylsiloxane radical W or an -O-CO-C6H4-CO-O- radical and R 1 has the meaning indicated above.
• these copolymers consist of 40 to 55 mol% of structural groups of the formula IVa and/or IVb, 40 to 55 mol% of structural groups of the formula II and 1 to 5 mol% of structural groups of the formula Ilia or IHb.
• the copolymers additionally contain up to 50 mol%, in particular up to 20 mol%, based on the sum of the structural groups a) , b) and c) , of structural groups whose monomer is a vinyl, acrylic acid or methacrylic acid derivative.
• the monomeric vinyl derivatives are preferably derived from a compound which is selected from the group styrene, ethylene, propylene, isobutene or vinyl acetate.
• the additional structural groups are in particular derived from acrylic acid or methyl acrylate.
• a preferred monomeric methacrylic acid derivative is to be regarded as methacrylic acid, methyl methacrylate and hydroxyethyl methacrylate .
• the number of repeating structural elements of the copolymers is not restricted here, but it has proven particularly advantageous to adjust the number of the structural elements such that the copolymers have an average molecular weight of 1000 to 200 000.
• the second component of the copolymers is an oxyalkylene glycol alkenyl ether, which is preferably employed in an amount of 40 to 55 mol%.
• R 1 , m and n have the meaning already mentioned above.
• a vinylic polyalkylene glycol polysiloxane or ester compound
• a preferred vinylic polyalkylene glycol compound derivatives corresponding to the formula VI are employed,
• R 6 can in turn either be R 1 or
• monomers are maleic acid N- (methylpolypropylene glycol) monoamide, maleic acid N- (methoxypolypropylene glycol-polyethylene glycol) monoamide, polypropylene glycol vinyl ether and polypropylene glycol allyl ether.
• R 6 ⁇ R 1 these are bifunctional vinyl compounds, whose polypropylene glycol- (polyethylene glycol) derivatives are bonded to one another via amide or ether groups (-0- or - OCH 2 -) .
• examples of such compounds are polypropylene glycol-bismaleamic acid, polypropylene glycol diacrylamide, polypropylene glycol dimethacrylamide, polypropylene glycol divinyl ether, polypropylene glycol diallyl ether.
• monomers are monovinylpolydimethylsiloxanes .
• suitable derivatives are those corresponding to the formula VIII,
• S is preferably hydrogen.
• Examples of such monomers having a vinyl function are polydimethylsiloxanepropylmaleamic acid or polydimethylsiloxanedipropyleneaminomaleamic acid. If R 7 ⁇ R 1 , they are divinyl compounds such as, for example, polydimethylsiloxane-bis (propylmaleamic acid) or polydimethylsiloxane-bis (dipropyleneaminomaleamic acid) .
• a suitable preferred derivative is one corresponding to the formula
• R 7 can either be R 1 or else
• R 7 R 1
• S is preferably hydrogen
• examples of such monovinylic compounds are polydimethylsiloxane- (l-propyl-3-acrylate) or polydimethylsiloxane- (l-propyl-3- methacrylate) .
• R 7 ⁇ R 1 these are divinyl compounds, such as, for example, polydimethylsiloxane-bis (l-propyl-3-acrylate) or polydimethylsiloxane-bis (l-propyl-3-methacrylate) .
• a vinylic ester compound in the context of the present invention derivatives corresponding to the formula X are preferably employed,
• S is COOM a or -COOR 5 and R 5 can be an aliphatic hydrocarbon radical having 3 to 20 C atoms, a cycloaliphatic hydrocarbon radical having 5 to 8 C atoms and an aryl radical having 6 to 14 C atoms, a and M have the abovementioned meaning.
• ester compounds are di-n-butyl maleate or fumarate or mono-n- butyl maleate or fumarate.
• V can in this case be W (that is a polydimethylsiloxane group) , which corresponds to a dialkenylpolydimethylsiloxane compound, such as, for example, divinylpolydimethylsiloxane .
• V can also be-O-CO-C6H 4 -CO-O- .
• These compounds are dialkenylphthalic acid derivatives.
• a typical example of such phthalic acid derivatives is diallyl phthalate.
• the molecular weights of the compounds which form the structural group c) can be varied within wide limits and are preferably between 150 and 10 000.
• a vinyl, acrylic acid or methacrylic acid derivative can be copolymerized.
• a monomeric vinyl derivative styrene, ethylene, propylene, isobutene or vinyl acetate is preferably used, as a monomeric acrylic acid derivative acrylic acid or methyl acrylate is preferably employed, while as a monomeric methacrylic acid derivative finally methacrylic acid, methyl methacrylate and hydroxyethyl methacrylate are preferably used.
• the aforementioned copolymers are disclosed in EP-A-736553
• the dispersion according to the invention can furthermore contain a copolymer whose basis is an oxyalkenyl glycol (meth) acrylic acid ester and the copolymer contains the following structural groups:
• R 1 is a hydrogen atom or the methyl group
• R 2 O is one type or a mixture of two or more types of an oxyalkylene group having 2-4 carbon atoms, with the proviso that two or more types of the mixture can be added either in the form of a block or in random form,
• R 3 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms
• m is a value which is the average number of the added moles of oxyalkylene groups, m being an integer in the range from 1 to 200.
• R 4 is a hydrogen atom or the methyl group
• M 1 is a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group or an organic amine group
• Typical monomers (a) are: hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polybutylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol mono (meth) acrylate, polyethylene glycol-polybutylene glycol mono (meth) acrylate, polypropylene glycol-polybutylene glycol mono (meth) acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, methoxypolypropylene glycol mono (meth) acrylate, methoxypolybutylene glycol mono (meth) acrylate, methoxypolyethylene glycol-polypropylene glycol mono (meth) acrylate, me
• Typical monomers (b) are: acrylic acid and methacrylic acid, mono- and divalent metal salts, ammonium salts and/or organic amine salts thereof.
• Typical monomers (c) are: esters of aliphatic alcohols having 1 to 20 C atoms with (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mono- and divalent metal salts, ammonium salts and/or organic amine salts thereof; mono- or diesters of unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid with aliphatic alcohols of 1 to 20 C atoms, with glycols having 2 to 4 C atoms, with (alkoxy) polyalkylene glycols of 2 to 100 added moles of the aforementioned glycols; unsaturated amides such as (meth) acrylamide and (meth) acrylalkylamide; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene; unsaturated sulfonic acids, such as (meth) allylsulfonic acid, sul
• a further subject of the invention is a process for the preparation of the dispersion according to the invention, in which a) a polycarboxylate ether in the form of a powder or as an aqueous solution of the polycarboxylate ether is added with stirring to an aqueous starting dispersion of titanium dioxide and the mixture is optionally diluted further with water or b) a titanium dioxide powder is dispersed in an aqueous solution of a polycarboxylate ether by means of a suitable dispersing unit and is subsequently optionally diluted further with water or c) the titanium dioxide powder is dispersed in an aqueous phase, preferably in water, and subsequently the resulting dispersion is added to an aqueous solution of the polycarboxylate ether.
• the mixing in of the dispersion can in this case be carried out under very low shear energy, for example by means of a propeller stirrer.
• the dispersion of the titanium dioxide powder can be carried out at low degrees of filling in equipment which introduces a comparatively low shear energy into the system (e.g. dissolvers, rotor-stator systems).
• shear energies of > 1000 kJ/m 3 must be applied in order to obtain a stable dispersion of low viscosity.
• High shear energies can be achieved, for example, using stirred ball mills, high- pressure homogenizers or planetary kneaders .
• a predispersion can initially be produced.
• Suitable dispersing units are understood as meaning those whose energy input suffices to disperse the titanium dioxide powder so that the aggregates have a mean diameter of less than 1 ⁇ m.
• the dispersion of the titanium dioxide powder can be carried out at low degrees of filling in equipment which introduces a comparatively low shear energy into the system (e.g. dissolvers, rotor-stator systems).
• shear energies of > 1000 kJ/m 3 must be applied in order to obtain a stable dispersion of low viscosity.
• High shear energies can be achieved, for example, using stirred ball mills, high- pressure homogenizers or planetary kneaders .
• a process disclosed in WO 2005/063369 can advantageously be employed, in which at least two streams of a predispersion are sprayed to a collision point by means of pumps, preferably high-pressure pumps, through in each case one nozzle into a milling space surrounded by a reactor housing, the milling space being flooded with the predispersion and it being removed from the milling space by means of overpressure of the predispersion flowing back into the milling space.
• pumps preferably high-pressure pumps
• At least two streams of a pre- dispersion are sprayed to a collision point by means of pumps, preferably high-pressure pumps, through in each case one nozzle in a reactor space surrounded by a reactor housing and water vapor is introduced into the reactor space through an opening such that in the reactor space a vapor atmosphere prevails which consists predominantly of water vapor, and the finely divided dispersion and vapor and/or partially condensed vapor, which consists mainly of water, are removed from the reactor space by means of overpressure of the entering water vapor on the gas inlet side .
• pumps preferably high-pressure pumps
• a predispersion can initially be produced.
• An advantageously employable starting dispersion is obtained by introducing into water an aggregated titanium dioxide powder having a specific surface area of 20 to 150 m /g, at least one amino alcohol having 1 to 6 carbon atoms and at least one carboxylic acid from the group comprising dibasic carboxylic acids and/or hydroxycarboxylic acids having 2 to 6 carbon atoms, producing a predispersion therefrom by energy input of less than 200 kJ/m 3 and subsequently by milling the predispersion by means of a high energy mill at a pressure of at least 500 bar producing a dispersion in which the aggregated titanium dioxide powder has a mean, volume-related aggregated diameter of less than 150 nm.
• the content of titanium dioxide is at least 20% by weight.
• the titanium dioxide employed can preferably be a pyrogenically prepared titanium dioxide.
• the amino alcohol is preferably present in the dispersion to 2.5 to 7.0 ⁇ mol/m 2 of specific surface area of Ti ⁇ 2 and the carboxylic acid to 1.0 to 3.5 ⁇ mol/m 2 of specific surface area of Ti ⁇ 2. Values for the amino alcohol of 3.3 to 5.0 ⁇ mol/m 2 of specific surface area of Ti ⁇ 2 and 1.5 to 2.5 ⁇ mol/m 2 of specific surface area of Ti ⁇ 2 for the carboxylic acid are particularly preferred.
• Suitable amino alcohols are: monethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, N, N- dimethylisopropanolamine, 3-amino-l-propanol, l-amino-2- propanol and/or 2-amino-2-methyl-l-propanol .
• Suitable carboxylic acids are: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, lactic acid, malic acid, tartaric acid and/or citric acid.
• This starting dispersion is distinguished, in addition to the low aggregate size of the titanium dioxide particles, by its stability and low viscosity. Further dispersions are contained in the still unpublished German patent application having the application number 102004037118.0 of July 30, 2004.
• a further subject of the invention is the use of the dispersion according to the invention as a concrete additive .
• a further subject of the invention is a cement-containing preparation which contains the dispersion according to the invention .
• the content of titanium dioxide in the cement- containing preparation is 0.01 to ⁇ 2% by weight, based on the cement .
• the particle diameter in the dispersion is determined by means of dynamic light scattering, measuring apparatus: Horiba LB-500.
• the relatively coarsely divided powders P5 and P6 are measured by means of laser diffraction according to ISO 13320-1.
• the BET surface area is determined according to DIN 66131. Standard mortar was prepared according to DIN EN 196. The strength was tested according to DIN 1164 on prisms of size 4 x 4 x 16 cm.
• Aeroxide ® P25 TiO 2 BET surface area 50 m 2 /g, content of titanium dioxide > 99.50% by weight.
• P2 titanium dioxide powder according to WO2005/054136
• Example A7 BET surface area 91 m 2 /g.
• P3 titanium-silicon mixed oxide powder according to DE-A- 102004001520, Example 12: BET surface area 43 m 2 /g, content of titanium dioxide 49% by weight, content of silicon dioxide 51% by weight.
• Aerosil ® 200 BET surface area 200 ⁇ 25 m 2 /g, content of silicon dioxide > 99.8% by weight
• TiPure ® R 706 BET surface area ⁇ 10 m 2 /g, content of titanium dioxide 93% by weight.
• P6 TiOxide ® TR 92, Huntsman: BET surface area ⁇ 10 m 2 /g, content of titanium dioxide 94% by weight.
• Polycarboxylate ether (PCE) is prepared according to EP-A- 1189955, Example 2, the amounts being modified such that a 45 percent solution is obtained.
• DIa 299 g of Pl are added to 1 kg of a solution of PCEl in water (concentration 102 g/1 of water) and dispersed using a ball mill.
• D2, D3, D4, D5 and D6 are prepared analogously to DIa using Pl, P2, P3, P4, P5 and P6, but using different amounts of PCEl solution and different powders.
• D7 contains no titanium dioxide, but only PCE and is not a dispersion.
• the composition of the dispersions is shown in Table 1. Table 1 : Dispersions
• a comparison of D3 and D4 in Table 2 also shows a further positive effect of the titanium dioxide content of the particles: at the same high concentration of the reactive solid of 0.5% of the binder, although approximately the same high early strengths are achieved, the superplasticizer requirement is about 30% higher with D4. This means that the workability of the fresh concrete is significantly less affected by reactive particles which contain titanium dioxide than by reactive silicic acids of the same specific surface area. This means a cost saving for the user, since he has to use less superplasticizer
• Figure 1 shows the heat development in the cement paste sample article in mW/g of cement in the period of time 0.5- 24 h after addition of the mixing water to the cement.
• the cement used was CEM I 42.5 Bernburg. DIa is added such that the amount of titanium dioxide is 0.5% by weight, based on the cement employed (curve 1) .
• the water/cement ratio was constant at 0.5.
• Comparison was carried out against a sample which contains no titanium dioxide (curve 2) .
• the heat development is to be attributed to the exothermic reaction of the silicate phases in the cement with water.
• the maximum in the curve obtained by calorimetry can be correlated with the development of strength in the cement, that is a maximum occurring at an earlier point in time means a development of early strength commencing earlier in the component .

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  • 2006-02-04 DE DE102006005094A patent/DE102006005094A1/de not_active Withdrawn
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