NOVEL SHRINKAGE-REDUCING AGENTS FOR MINERAL BINDERS

Abstract

The invention relates to the use of carboxylic acid-based polyoxyalkylenes as low-emissions shrinkage reducers in mineral binders, to methods of reducing shrinkage and to corresponding compositions.

Claims

1. A shrinkage-reducing agent comprising a polyoxyalkylene of the formula (I) ##STR00003## wherein R is independently an a-valent, linear or branched, saturated, monounsaturated or polyunsaturated, aliphatic, cycloaliphatic or aromatic hydrocarbyl radical having 3 to 38 carbon atoms, where the hydrocarbyl radical is substituted by a polyoxyalkylene radicals A, a is from 1 to 4, n is from 0 to 40, m is from 0 to 40, wherein the sum total of n and m=4 to 80, where the units that n and m refer to are distributed in the polyether chain either in blocks or randomly and the units that n and m refer to constitute the mean values of the possible statistical distribution of the actual structures present.

2. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), the R radical is independently an aliphatic hydrocarbyl radical having from 3 to 38 carbon atoms, where the carbon chain is terminally substituted by 1 or 2 polyoxyalkylene radicals A and a is the number of polyoxyalkylene radicals A and is 1 or 2.

3. The shrinkage-reducing agent according to claim 1, wherein the R radicals derive from a fatty acid or a dimer fatty acid.

4. The shrinkage-reducing agent according to claim 1, wherein the R radicals derive from hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, 2-ethylhexanecarboxylic acid, isononanoic acid, 3,5,5-trimethylhexanecarboxylic acid, neodecanoic acid, isotridecanecarboxylic acid, isostearic acid, undecylenoic acid, oleic acid, linoleic acid, ricinoleic acid, linolenic acid, benzoic acid, cinnamic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanecarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid or the dimer fatty acids that derive from the aforementioned unsaturated carboxylic acids.

5. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), a is less than 3.

6. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), m=2 to 30 and n=2 to 30, and the sum total of n and m is 6 to 40.

7. The shrinkage-reducing agent according to claim 1, wherein the polyoxyalkylenes of the formula (I) have a weight-average molar mass of 300 to 15 000 g/mol.

8. The shrinkage-reducing agent according to claim 1, wherein the polyoxyalkylenes of the formula (I) have been applied to a support.

9. The method of reducing shrinkage of building materials comprising mineral binders, especially cementitious binders, preferably of mortar, screed, concrete or slurries, wherein at least one polyoxyalkylene of the formula (I) according to the provisions of claim 1 is added to an unhardened building material mixture.

10. The method according to claim 9, wherein the polyoxyalkylene of the formula (I) is added to the building material mixture in an amount of 0.001% to 6.0% by weight, based on the dry weight of the mineral binder.

11. The method according to claim 9, wherein the building material mixture comprises customary admixtures and/or additives and/or aggregate.

12. The method according to claim 9, wherein i) the at least one polyoxyalkylene of the formula (I), mineral binders, admixtures, additives and/or aggregate are mixed without addition of water and water is added to the premix thus obtained at a later juncture, or ii) the individual components are mixed together with water.

13. The method according to claim 9, wherein the at least one polyoxyalkylene of the formula (I) is mixed with the mineral binder and/or the rock flour during the process of production or delivery of the building material.

14. The building material composition comprising i) at least one mineral binder, preferably a cementitious binder, and ii) at least one polyoxyalkylene of the formula (I) according to the provisions from claim 1.

15. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), a is less than 1.

16. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), m is from 4 to 20, and n is from 4 to 20, and the sum total of n and m is from 8 to 20.

17. The use according to claim 1, wherein the polyoxyalkylenes of the formula (I) have a weight-average molar mass of 500 to 2500 g/mol.

18. The method according to claim 9, wherein the polyoxyalkylene of the formula (I) is added to the building material mixture in an amount of 0.1% to 3% by weight, based on the dry weight of the mineral binder.

19. The shrinkage-reducing agent according to claim 2, wherein the R radicals derive from hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, 2-ethylhexanecarboxylic acid, isononanoic acid, 3,5,5-trimethylhexanecarboxylic acid, neodecanoic acid, isotridecanecarboxylic acid, isostearic acid, undecylenoic acid, oleic acid, linoleic acid, ricinoleic acid, linolenic acid, benzoic acid, cinnamic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanecarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid or the dimer fatty acids that derive from the aforementioned unsaturated carboxylic acids.

20. The shrinkage-reducing agent according to claim 1, wherein, in formula (I), the R radical is independently an aliphatic hydrocarbyl radical having from 5 to 17 carbon atoms, where the carbon chain is terminally substituted by 1 or 2 polyoxyalkylene radicals A and a is the number of polyoxyalkylene radicals A and is 1 or 2.

Description

EXAMPLES

GPC Measurements:

[0059] GPC measurements for determining the polydispersity and average molar masses Mw were conducted under the following measurement conditions: SDV 1000/10 000 ? column combination (length 65 cm), temperature 30? C., THF as mobile phase, flow rate 1 ml/min, sample concentration 10 g/l, RI detector, evaluation against polypropylene glycol standard.

Determination of OH Number:

[0060] Hydroxyl numbers were determined according to the method DGF C-V 17 a (53) of the Deutsche Gesellschaft f?r Fettwissenschaft [German Society for Fat Science]. This involved acetylating the samples with acetic anhydride in the presence of pyridine and determining the consumption of acetic anhydride by titration with 0.5 n potassium hydroxide solution in ethanol using phenolphthalein.

Determination of Viscosity

[0061] Viscosities were measured in accordance with DIN 53019 with a Haake RV12 rotary viscometer at 25? C.

Determination of the VOC Content:

a) Test Chamber Experiments

[0062] Test chamber experiments were conducted in accordance with the test method Bestimmung fluichtiger organischer Verbindungen zur Charakterisierung emissionskontrollierter Verlegewerkstoffe, Klebstoffe, Bauprodukte und Parkettlacke [Determination of Volatile Organic Compounds for Characterization of Emissions-Controlled Laying Materials, Adhesives, Construction Products and Parquet Varnishes] from the German Association for the Control of Emissions in Products for Flooring Installation, Adhesives and Building Materials (GEV), version of Apr. 15, 2013. Mortar samples that contained the respective shrinkage reducer were made up with water, introduced into a metal dish and placed into a 30 l test chamber. Storage was effected at 23? C., 50% rel. humidity and exchange of air at 0.5 per hour. After 3, 10 and 28 days, two samples each were taken from the gas space of the test chamber: one sample for the analysis of the emissions by GC-MS (Tenax), the other sample for determination of aldehydes by means of HPLC (DNPH).

b) Quick Method by Means of GC

[0063] VOC measurements were conducted according to DIN EN ISO 11890-2 Paints and varnishesDetermination of volatile organic compound (VOC) content by a gas chromatography method, using tetradecane having a boiling point of 251? C. under standard conditions as marker substance. VOCs are considered to be all compounds having retention times below that of the marker substance. The VOC content was determined by calculation from the peak areas and represents the proportion by mass of volatile organic constituents in percent based on the total amount of the sample analyzed.

Mixing of the Building Material (Building Material Mixture):

[0064] The production of a mixture was effected in accordance with DIN EN 206-1. Cement and any admixtures, additives and aggregate were premixed in a mixer, for example a pan mixer. After completion of addition of water and after subsequent addition of superplasticizer or concrete plasticizer, the mixture was mixed again in each case.

Determination of the Consistency of the Fresh Building Material Mixture:

[0065] Slump flow was determined according to DIN EN 12350-5 or according to DIN EN 13395-1. The determination of slump was conducted in accordance with DIN EN 12350-8. Rather than the slump cone, a H?germann cone was used. Further methods employed are described in the DAfStb [German Committee for Structural Concrete] guide Herstellung und Verwendung von zementgebundenem Vergussbeton und Vergussm?rtel [Production and Use of Cement-Bound Pouring Concrete and Pouring Mortar].

Determination of the Air Pore Content of the Fresh Building Material Mixture:

[0066] The air pore content was determined in accordance with DIN EN 12350-7. The volume of the air content test instrument was 1 litre or 5 litres.

Determination of Early Shrinkage:

[0067] Shrinkage and expansion operations in the building material samples during the setting process were measured by means of a shrinkage channel. Fresh mortar is introduced into a metal channel made of stainless steel. A ram mounted in a movable manner on one side of the channel transmits the change in length to a highly sensitive transducer. At the other end of the channel is a barbed hook that holds the sample against the wall of the channel. An identical hook is present on the transducer ram. The sample is held in a virtually frictionless manner in the channel.

Determination of the Long-Term Shrinkage of the Solid Building Material Mixture:

[0068] Shrinkage was conducted according to DIN 52450 (1985). The alternative method is based on this standard. The difference is that test specimens with dimensions of 100 mm?100 mm?500 mm and corresponding test instruments were used.

Determination of Compressive and Flexural Tensile Strengths of the Solid Building Material Mixture:

[0069] Compressive and flexural tensile strengths were tested according to DIN EN 12390-3, DIN EN 12390-5, DIN EN 196-1 and DIN EN 13892-2.

Synthesis Examples for the Shrinkage Reducers

Example 1

Preparation of a Polyoxyalkylene from 3,5,5-trimethylhexanoic Acid and 8 Mol of PO

[0070] An initial charge of 806 g of 3,5,5-trimethylhexanoic acid and 18.5 g of KOH in a 5 litre autoclave was heated to 130? C. while stirring. The reactor was evacuated down to an internal pressure of 30 mbar in order to remove any volatile ingredients present by distillation, and inertization was effected with nitrogen. 2367 g of propylene oxide were metered in at internal temperature 130? C. and an internal pressure of 3 to 4 bar (absolute) within 4 h. After further reaction at 130? C. for 1.5 h, volatile components were removed by distillation under reduced pressure at 130? C. The alkoxylation product was cooled down to below 90? C., neutralized with phosphoric acid and discharged from the reactor via a filter. The product was almost colorless and of low viscosity at room temperature. The OH number was 101 mg KOH/g, and the acid number 0.1 mg KOH/g. According to GPC analysis, the product has a weight-average molar mass M.sub.w of 680 g/mol and a polydispersity M.sub.w/M.sub.n of 1.11.

Example 2

Preparation of a Polyoxyalkylene from 3,5,5-trimethylhexanoic Acid and 12 Mol of EO

[0071] An initial charge of 806 g of 3,5,5-trimethylhexanoic acid and 12.5 g of KOH in a 5 litre autoclave was heated to 130? C. while stirring. The reactor was evacuated down to an internal pressure of 30 mbar in order to remove any volatile ingredients present by distillation, and inertization was effected with nitrogen. 2689 g of ethylene oxide were metered in at internal temperature 160? C. and an internal pressure of max. 4.5 bar (absolute) within 2 h 40 min. After further reaction at 160? C. for 1 h, volatile components were removed by distillation under reduced pressure at 160? C. The alkoxylation product was cooled down to below 90? C., neutralized with phosphoric acid and discharged from the reactor via a filter. The product was almost colorless and of low viscosity at room temperature. The OH number was 88.5 mg KOH/g, and the acid number 0.3 mg KOH/g. According to GPC analysis, the product has a weight-average molar mass M.sub.w of 680 g/mol and a polydispersity M.sub.w/M.sub.n of 1.12.

Example 3

Preparation of a Polyoxyalkylene from Neodecanoic Acid and 8 Mol of EO

[0072] An initial charge of 689 g of neodecanoic acid and 3.6 g of potassium hydroxide solution (45%) in a 5 litre autoclave was heated to 130? C. while stirring. The reactor was evacuated down to an internal pressure of 30 mbar in order to remove any volatile ingredients present by distillation, and inertization was effected with nitrogen. 1408 g of ethylene oxide were metered in at internal temperature 170? C. and an internal pressure of max. 4.5 bar (absolute) within 3.5 h. After further reaction at 170? C. for 0.5 h, volatile components were removed by distillation under reduced pressure. The alkoxylation product was cooled down to below 90? C., neutralized with lactic acid and discharged from the reactor via a filter. The product was almost colorless and of low viscosity at room temperature. The OH number was 101.9 mg KOH/g, and the acid number 0.1 mg KOH/g. According to GPC analysis, the product has a weight-average molar mass M.sub.w of 540 g/mol and a polydispersity M.sub.w/M.sub.n of 1.09.

Example 4

Preparation of a Polyoxyalkylene from 3,5,5-trimethylhexanoic Acid, 8 Mol of PO and 8 Mol of EO

[0073] Preparation according to Example 1, except that the autoclave was initially charged with 403 g of 3,5,5-trimethylhexanoic acid and 5.8 g of potassium methoxide, and a homogeneous mixture of 1182 g of propylene oxide and 897 g of ethylene oxide was metered in at 130? C. The phosphoric acid-neutralized alkoxylation product was almost colorless and of low viscosity at room temperature. The OH number was 58.2 mg KOH/g, and the acid number 0.2 mg KOH/g.

[0074] According to GPC analysis, the product has a weight-average molar mass M.sub.w of 935 g/mol and a polydispersity M.sub.w/M.sub.n of 1.12.

Example 5

Preparation of a Polyoxyalkylene from Benzoic Acid and 5 Mol of EO and 5 Mol of PO

[0075] Preparation according to Example 1, except that the autoclave was initially charged with 488 g of benzoic acid and 7.5 g of sodium methoxide, and first 880 g of ethylene oxide and then 1160 g of propylene oxide were metered in at 130? C. The phosphoric acid-neutralized alkoxylation product of blockwise structure was pale yellowish and of low viscosity at room temperature. The OH number was 90.1 mg KOH/g, and the acid number 0.1 mg KOH/g. According to GPC analysis, the product has a weight-average molar mass M.sub.w of 610 g/mol and a polydispersity M.sub.w/M.sub.n of 1.14.

Example 6

Preparation of a Polyoxyalkylene from Oleic Acid and 12 Mol of EO

[0076] Preparation according to Example 3, except that the autoclave was initially charged with 561 g of oleic acid and 2.5 g of potassium hydroxide solution (45%), and 1056 g of ethylene oxide were metered in at 150? C. The non-neutralized alkoxylation product was brownish and of low viscosity at room temperature. The OH number was 71.3 mg KOH/g, and the acid number 0.0 mg KOH/g. According to GPC analysis, the product has a weight-average molar mass M.sub.w of 785 g/mol and a polydispersity M.sub.w/M.sub.n of 1.16.

Example 7

Preparation of a Powder in Supported Form

[0077] The stirrer bowl of an intensive mixer (for example from Eirisch) was initially charged with 333 g of silica and 67 g of the polyoxyalkylene according to Example 1 (3,5,5-trimethylhexanoic acid+8 PO). This was followed by mixing at 2000 rpm for 5 minutes.

Analysis of VOC Content:

[0078] The pure polyoxyalkylenes were analyzed for their VOC content by gas chromatography by the quick test described.

TABLE-US-00001 TABLE 1 VOC content of shrinkage reducers VOC relative to hexylene glycol Example Shrinkage reducer (%) (noninventive) hexylene glycol 100 (noninventive) neopentyl glycol 100 1 3,5,5-trimethylhexanoic acid + 8 PO 0.29 2 3,5,5-trimethylhexanoic acid + 12 EO <0.1 3 neodecanoic acid + 8 EO <0.1 4 3,5,5-trimethylhexanoic acid + 8 PO/ <0.1 8 EO 5 benzoic acid + 5 EO + 5 PO 0.2 6 oleic acid + 12 EO <0.1

[0079] For selected samples, by the GEV method, test chamber tests (as described above) on mortar samples modified with various shrinkage reducers were conducted. The dosage was 0.3% active ingredient based on the overall mortar.

[0080] For the assessment of VOC emissions, what is called the TVOC (total volatile organic content; retention range C6-C16) is cited and is reported in toluene equivalents.

TABLE-US-00002 TABLE 2 TVOC values of mortar samples with shrinkage reducers in the test chamber test by the GEV method TVOC on day 3 TVOC on day 28 Conventional shrinkage reducer neopentyl glycol 3710 ?g/m.sup.3 1980 ?g/m.sup.3 Inventive compound 50 ?g/m.sup.3 <10 ?g/m.sup.3 Example 1 Limit under GEV criteria*: e.g. EC1.sup.plus ?750 ?g/m.sup.3 ?60 ?g/m.sup.3 e.g. EC1 ?1000 ?g/m.sup.3 ?100 ?g/m.sup.3 e.g. EC2 ?3000 ?g/m.sup.3 ?300 ?g/m.sup.3 *for product group 1: mineral products.

[0081] The conventional shrinkage reducer does not meet any of the GEV criteria that currently represent the state of the art for low-emissions building materials. By contrast, the mortar with the inventive shrinkage reducer (Example 1) achieves a level several times below the GEV criteria. The further compounds of the invention according to Examples 2 to 7 achieve comparably low TVOC values.

[0082] The detection of the shrinkage-reducing properties of the substances according to the invention was conducted on a building material mixture formulation consisting inter alia of 330 kg/m.sup.3 cement, 1700 kg/m.sup.3 rock flour and aggregate, and 210 kg of water. The difference between the comparative mixtures was merely in the shrinkage-reducing component.

TABLE-US-00003 TABLE 3 Indices of the fresh and solid building material mixture: MIXTURE A B C D E F G Shrinkage none neopentyl hexylene from from from from reducer (SR) glycol glycol Ex. 1 Ex. 2 Ex. 3 Ex. 4 SR dosage 2.0% 2.0% 2.0% 2.0% 2.0% 2.0% [% by wt. of cement] Slump after 235 240 230 225 230 240 230 5 min mm mm mm mm mm mm mm Compressive 34.8 34.5 33.7 39.2 31.1 33.4 35.7 strength after MPa MPa MPa MPa MPa MPa MPa 28 d

TABLE-US-00004 TABLE 4 Early shrinkage values: The figures given are standardized to the reference mixture. By definition, the values for the reference mixture at every measurement point are 100%. A value of less than 100% means that the shrinkage of this mixture was less than the reference mixture. A B C D E F G 1 h 100% 30.0% 32.9% 12.9% 25.7% 100.4% 28.6% 5 h 100% 26.0% 41.0% 25.3% 76.4% 85.5% 24.9% 10 h 100% 35.4% 20.2% 59.4% 64.2% 65.0% 21.9% 15 h 100% 68.8% 26.8% 42.7% 76.3% 41.3% 33.8% 20 h 100% 77.8% 58.1% 43.2% 69.2% 46.1% 42.6% 24 h 100% 78.3% 65.7% 43.2% 67.8% 47.0% 44.6% 32 h 100% 78.6% 67.3% 42.9% 67.5% 46.8% 44.8% 48 h 100% 77.6% 67.0% 42.3% 66.7% 46.2% 44.8%

TABLE-US-00005 TABLE 5 Long-term shrinkage values according to Graf-Kaufmann A B C D E F G [mm/m] [mm/m] [mm/m] [mm/m] [mm/m] [mm/m] [mm/m] 1 d ?0.253 ?0.247 ?0.169 ?0.051 ?0.182 ?0.140 ?0.044 5 d ?0.476 ?0.333 ?0.300 ?0.218 n.d. ?0.316 ?0.227 7 d n.d. ?0.393 ?0.333 ?0.278 ?0.391 ?0.407 ?0.284 14 d ?0.589 ?0.473 ?0.422 ?0.351 n.d. ?0.491 ?0.364 21 d ?0.633 ?0.498 ?0.460 ?0.376 ?0.511 ?0.511 ?0.387 28 d ?0.638 ?0.507 ?0.496 ?0.391 ?0.516 ?0.531 ?0.402 56 d ?0.688 ?0.520 ?0.498 ?0.451 n.d. ?0.563 ?0.470

[0083] The shrinkage-reducing properties of the compounds according to the invention were tested in a further building material formulation (Table 6) of the following composition: 647 kg/m.sup.3 cement, 260 kg/m.sup.3 rock flour, 1293 kg/m.sup.3 sand of grain size 0-2 mm and 453 kg/m.sup.3 water. References used were mixtures without shrinkage reducer and with neopentyl glycol. Shrinkage was conducted according to DIN 52450 (1985) on test specimens with dimensions of 400 mm?400 mm?1600 mm.

TABLE-US-00006 TABLE 6 Long-term shrinkage values according to DIN 52450 (1985) Neopentyl no SR glycol from Ex. 1 from Ex. 2 from Ex. 4 [mm/m] [mm/m] [mm/m] [mm/m] [mm/m] 1 d ?0.10 ?0.09 ?0.05 ?0.12 ?0.06 7 d ?0.44 ?0.30 ?0.25 ?0.35 ?0.15 14 d ?0.76 ?0.38 ?0.39 ?0.40 ?0.30 21 d ?0.89 ?0.58 ?0.50 ?0.60 ?0.51 28 d ?1.00 ?0.62 ?0.65 ?0.70 ?0.55 56 d ?1.15 ?0.72 ?0.65 ?0.72 ?0.62