Patent Grant
6864344
The present invention relates to storage-stable sulfonated condensation products, a process for preparing them and their use.
It is sufficiently known that hydraulically setting binders such as cement, lime, gypsum, CaSO4 hemihydrates and anhydrites can be fluidized by addition of dispersants, which makes it possible to set desired low water/binder ratios. Classical dispersants which have been used for over 20 years are melamine-formaldehyde-sulfite (MSF) resins and naphthalenesulfonic acid-formaldehyde (NSF) resins which have been continuously developed further in recent years so as to be able to meet increased expectations.
Thus, DE 195 38 821 describes low-cost MFS resins containing a high proportion of sulfite. According to EP 690 083, a cost reduction is achieved by partial replacement of melamine by urea in a 2-stage process with addition of coreactants such as aminosulfonic acids, aminocarboxylic acids and caprolactam, etc., although this advantage is partly negated by an oxidation step to eliminate the excess sulfite.
Also customary is the addition of sulfanilic acid, as disclosed, for example, in DE 44 11 797 or in DE 196 09 614, in which case the sulfanilic acid is supplemented by polyoxyalkylene derivatives and/or aldehyde acid derivatives.
However, all these condensation products have the disadvantage that the spray drying of aqueous solutions of conventional fluidizers has an extremely adverse effect on the early strength development which is of particular importance for CaSO4 applications due to the high thermal stress during drying.
It is therefore an object of the present invention to develop storage-stable sulfonated condensation products based on an amino resin former having at least two amino groups and sulfite and/or naphthalenesulfonic acid together with formaldehyde which when used as additives for hydraulically setting additives do not display the abovementioned disadvantage of a thermal change but are instead stable over a wide temperature range.
According to the invention, this object is achieved by sulfonated condensation products which further comprise at least one nitrogen-containing formulation auxiliary selected from among compounds of the formula (I)
R1—NH—X—Y—R2
where
R1 and R2 are each, independently of one another, H,
—CH3, —C2H5, —C3H7, —(CH2) n—CH2—
Contrary to all expectations, it has been found that the storage-stable sulfonated condensation products of the invention display, in addition to the desired temperature stability, a drastic reduction in the undesirable outgassing of formaldehyde and/or ammonia which has hitherto been typical for this class of product. This effect displayed so clearly was not foreseeable.
As regards the components of the storage-stable sulfonated condensation products, the invention provides for melamine and/or urea to be used as preferred amino resin formers. These can be replaced to an extent of up to 70% by weight by thiourea, dicyandiamide, a guanidine (salt) and mixtures thereof, although ranges of from 30 to 50% by weight are to be preferred.
Likewise, urea and also thiourea, N-methylurea, 2-imidazolidinone and/or anthranilamide represent typical organic formulation auxiliaries for the purposes of the invention.
The nitrogen-containing formulation auxiliary can, if desired, be partly incorporated into the condensate of amino resin former, formaldehyde and sulfite component or form an adduct with this.
For some applications, it has been found to be advantageous to use the condensation products as aqueous solutions. Aqueous solutions having a solids content of from 20 to 60% by weight and a viscosity at 95° C. of from 0.5 to 250 mm2.s−1 are particularly useful for this purpose. On the other hand, the condensation products can also be used as dry products having a residual moisture content of <5% (weight/weight).
Apart from the storage-stable sulfonated condensation products themselves, the present invention also claims a process for preparing them, in which
Furthermore, this process provides for the condensation products obtained in this way to be dried to a preferred residual moisture content of <5%, which should preferably be carried out by evaporation of the water under reduced pressure, in a spray drier or on a roller dryer.
As an alternative method of preparing the condensation products claimed, it is proposed that sulfonated melamine-formaldehyde condensation products, sulfonated melamine-urea-formaldehyde condensation products or naphthalenesulfonic acid-formaldehyde condensation products be admixed with from 0.1 to 50% by weight, based on the content of solid active components, of a formulation auxiliary of the formulae (I) and/or (II) defined above or mixtures thereof and, if desired, dried to a residual moisture content of <5%.
The storage-stable sulfonated condensation products are used either as additives for inorganic binders, e.g. cement, lime, gypsum, CaSO4 hemihydrates and anhydrites, in an amount of from 0.01 to 20% by weight, based on the amount of the inorganic binders used, or else as additive for hydraulically setting dry mixes which comprise inorganic binders, in which case preference is given to amounts of from 0.01 to 20% by weight, based on the amount of the inorganic binders used.
Overall, the storage-stable sulfonated condensation products of the invention represent a significant advance in respect of the thermal stability of these condensation products and also take account of the increased demands made of environmentally friendly products.
The following examples illustrate these advantages of the condensation products of the invention.
332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20% strength aqueous sodium hydroxide solution were placed in a round-bottom flask. 126.0 g of melamine were subsequently introduced, the solution was heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of 20% strength NaOH were added and the mixture was heated at 80° C. until the sulfite is completely incorporated.
After the sulfite had been completely incorporated, 56.0 g of H2SO4 (10% strength) were added and condensation was then carried out at 80° C. until the viscosity was 9.1 cSt; finally, 66.5 g of a 20% strength sodium hydroxide solution were added and the mixture was cooled to room temperature (RT).
The finished solution displayed the following physical data:
This solution was dried in a spray drier to give a colorless powder; HCHOfree content of the powder after drying: 0.22%.
Examples according to the invention: (with formulation auxiliary)
332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20% strength aqueous sodium hydroxide solution were placed in a round-bottom flask. 126.0 g of melamine were subsequently introduced, the solution was heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a 20% strength aqueous sodium hydroxide solution were added and the mixture was heated at 80° C. until the sulfite is completely incorporated.
After the sulfite had been completely incorporated, 13.6 g of anthranilamide and 37.0 g of N-methylurea and also 56.0 g of H2SO4 (10% strength) and 25.3 g of water were added and condensation was carried out at 80° C. until the viscosity was 9.1 cSt; finally, 20.9 g of a 20% strength sodium hydroxide solution were added and the mixture was cooled to RT.
The finished solution displayed the following physical data:
This solution was dried in a spray drier to give a colorless powder; HCHOfree content of the powder after drying: 0.19%.
332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20% strength aqueous sodium hydroxide solution were placed in a round-bottom flask. 126.0 g of melamine were subsequently introduced, the solution was heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a 20% strength aqueous sodium hydroxide solution were added and the mixture was heated at 80° C. until the sulfite is completely incorporated.
After the sulfite had been completely incorporated, 56.0 g of H2SO4 (10% strength) were added and condensation was carried out at 80° C. until the viscosity was 9.1 cSt; 13.6 g of anthranilamide, 25.8 g of 2-imidazolidinone and 20.1 g of water were then added and the solution was made alkaline by addition of 14.7 g of a 20% strength sodium hydroxide solution and cooled to RT.
The finished solution displayed the following physical data:
This solution was dried in a spray drier to give a colorless powder; HCHOfree content of the powder after drying: 0.08%.
332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20% strength aqueous sodium hydroxide solution were placed in a round-bottom flask. 126.0 g of melamine were subsequently introduced, the solution was heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a 20% strength aqueous sodium hydroxide solution and also 37.0 g of N-methylurea, 76.1 g of thiourea and 150.6 g of water were added and the mixture was heated at 80° C. until the sulfite is completely incorporated.
After the sulfite had been completely incorporated, 56.0 g of H2SO4 (10% strength) were added and condensation was carried out at 80° C. until the viscosity was 3.9 cSt; finally, 22.2 g of a 20% strength sodium hydroxide solution were added and the mixture was cooled to RT.
The finished solution displayed the following physical data:
This solution was dried in a spray drier to give a colorless powder; HCHOfree content of the powder after drying: 0.07%.
332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20% strength aqueous sodium hydroxide solution were placed in a round-bottom flask. 126.0 g of melamine were subsequently introduced, the solution was heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a 20% strength sodium hydroxide solution and also 37.0 g of N-methylurea, 19.0 g of thiourea and 92.8 g of water were added and the mixture was heated at 80° C. until the sulfite is completely incorporated.
After the sulfite had been completely incorporated, 56.0 g of H2SO4 (10% strength) were added and condensation was carried out at 80° C. until the viscosity was 5.3 cSt; finally, 15.8 g of a 20% strength sodium hydroxide solution were added and the mixture was cooled to RT.
The finished solution displayed the following physical data:
This solution was dried in a spray drier to give a colorless powder; HCHOfree content of the powder after drying: 0.11%.
In the following, the properties of the resin-containing solutions and the powders produced therefrom were compared in an α-hemihydrate environment:
The fluidized plaster slurries were poured from the mixing cup onto a glass plate in one action; after determining the spread (SP), setting was monitored by means of a Vicat needle about 1 cm from the edge of the gypsum plaster cake.
It can be seen that, in examples 2 to 4 according to the invention, setting of the gypsum plaster mix remains unchanged within the limits of accuracy when the solution has been spray dried to give a powder, while example 1 (comparison) without addition according to the invention of a formulation auxiliary displays a significantly prolonged setting time.
The same significant result can be seen in the change in the HCOHfree values after drying (cf. examples 1 to 5). In example 1 (comparison) there is a relatively large decrease in the concentration of unreacted formaldehyde, while the resins of examples 2 to 4 according to the invention display excellent thermal stability during drying.
| Number | Date | Country | Kind |
|---|---|---|---|
| 199 46 591 | Sep 1999 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCTEP00/09587 | 9/29/2000 | WO | 00 | 3/20/2002 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO0123450 | 4/5/2001 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3830782 | Kempter et al. | Aug 1974 | A |
| 4069062 | Burge | Jan 1978 | A |
| 4430469 | Burge et al. | Feb 1984 | A |
| 4585853 | Plank et al. | Apr 1986 | A |
| 4666979 | Plank et al. | May 1987 | A |
| 5393811 | Moran et al. | Feb 1995 | A |
| 5705599 | Felixberger et al. | Jan 1998 | A |
| 5989391 | Watanabe et al. | Nov 1999 | A |
| 6346588 | Fenchl et al. | Feb 2002 | B1 |
| 6566459 | Dopico et al. | May 2003 | B1 |
| Number | Date | Country |
|---|---|---|
| 21 59 737 | Jun 1973 | DE |
| 0 238 930 | Sep 1987 | EP |
| 0 690 083 | Jan 1996 | EP |
| 893 901 | Apr 1962 | GB |
| 595 366 | Sep 1987 | GB |
| WO-96 34027 | Oct 1996 | WO |
