DE4407028C2 - Use of quaternized organic ammonium compounds to accelerate drainage in the formation of fragments of ceramic slips - Google Patents

Description

In the ceramic industry, articles are sorted according to different Molding process made. For the production more complex Forming has proven particularly successful in slip casting. Here is a mixture of the ceramic raw materials, the so-called mass, mixed with liquid, usually water, and thus into liquid Form, the so-called slip.

Clays, kaolins, feldspar, quartz, Metal oxides such as aluminum oxide or zirconium oxide, as well Non-oxides such as silicon nitride or silicon carbide Use. To control the rheological properties of the Slips, such as viscosity and thixotropy, are liquefied and dispersants used. As such, electrolytes serve which dissociate in the solution medium; usually sodium silicates, soda, polycarboxylic acid salts or extracts such as B. Humic acids and plant extracts. The slip is placed in a porous form in which the solution medium withdrawn through the pores and thereby a firmly connected Layer of raw materials is generated; this so-called broken glass represents an exact representation of the shape.

In the past, it was only customary to use this drainage system To achieve capillary suction power of plaster molds, so are today  increasingly used porous plastic molds. Since the Capillary forces in these plastic forms to drain the If the slip is not sufficient, the slip in the form with pressure pressurized so that a pressure filtration of the water through the porous surface takes place in the plastic mold. With this as Die-casting process is called depending on the pressure used, differentiate between low, medium and high pressure. From Low pressure is spoken at pressures <3 bar, at medium pressure Pressures of approx. 5 bar and high pressure at pressures <15 bar.

When making objects using one of these casting processes it is desirable that the formation of the body through Filtration to the desired thickness, d. H. Body thickness, in as short as possible. It is known that this is due to the Selection of certain raw materials can be achieved, in particular the corresponding grain structure plays a role, but that with one high fines content in these masses in most cases there is no sufficient body formation at the desired time. On the other hand, it must be taken into account that the fine grain fraction plays a crucial role in the strength of the body, by also reducing the strength of the Casting decreases in the raw state. This will handle such Castings problematic. Because of this, the reduction of the Finest grain fraction set a limit. For fine-grained masses Furthermore, segregation often occurs through sedimentation, which leads to Formation of a cast skin leads. This phenomenon occurs in die casting significantly increased so that there is a need for funds that only cause little sedimentation. Furthermore, the Die casting, as discoloration of the filtrate shows, is part of the Very fine particles are discharged with the filtrate during dewatering. This undesirable phenomenon should also be prevented by suitable means be eliminated.  

In US Pat. No. 4,892,663, an aqueous slurry of ground or crumbled coal is added Freed from water by filtration for transport purposes, with the addition of quaternary Ammonium compounds a lower water filter cake is obtained; its properties are irrelevant because it will be destroyed again for the transportation of the coal.

Quality criteria with regard to composition, shape and body strength as well Usage properties of an end product, that of sensitive composite slips or shards are necessary that also have to withstand a ceramic fire the transportation of coal greens is of no importance.  

In practice, attempts have been made to speed up the body formation speed by appropriate selection of the dispersants used to accelerate, but this is only possible to a limited extent. Also was tries to use known primary and secondary flocculants. Known primary flocculants are e.g. B. iron III chloride and aluminum sulfate; polyacrylamides in anionic, cationic and nonionic form. The combination of Disper but yeast and flocculants mostly fail because that flocculants interfere with the dispersion system. Leave many times these funds only during the preparation of the Mix as a template in the mixing water with subsequent stirring add solids; an addition to the finished slip leads to viscosity problems, however, so that the pourability is not more is guaranteed.

Also the combination of a correctly structured grain spectrum with one of the known suitable dispersing and liquefying agents as well as a less disruptive flocculant leads to results, those with regard to a more universal applicability of the dispersant medium-flocculant combinations, regardless of the time of addition, are still very unsatisfactory. Additives are therefore required with those slips that are used for the conventional pressure-free casting process are also made suitable for die casting. Therefor is an essential requirement that the rheology of the slip is affected only slightly or not at all, and that have the respective aids entered in the finished slip, without increasing its viscosity and impairing the pourability.

The task was therefore to find additives with which the rheological Properties, viscosity and pourability, even when entered in the lighted Slurry, not impaired, the formation of cullet improved and the sedimentation and Throughput phenomena can be reduced.  

It has now surprisingly been found that the rheological Eigen the speed and quality of the body formation significantly improved as well as sedimentation and flow appearances can be reduced if in ceramic slurries Acceleration of drainage during the formation of cullets in the Casting process Ammonium compounds in quaternized form be used.

The ammonium compounds used can be compounds of the general formula

be, wherein R ₁ , R ₂ , R ₃ and R ₄ one or two alkyl radicals C ₄ -C ₂₀ , a group tetramethylbutylphenoxyethoxyethyl, a benzyl group -CH ₂ C ₆ H ₅ , a pyridine or quinoline ring instead of R ₁ + R ₂ + R _{3 can} mean and the remaining substituents are hydrogen or alkyl groups with C ₁ -C ₄ , and AU represents any anion.

Compounds of this formula are, for example, alkylammonium salts such as
Fatty amine trimethyl ammonium sulfate with C ₈ -C ₂₂ ,
Distearyldimethylammonium chloride,
Tetrabutylammonium chloride, bromide or hydroxide,
Alkylarylammonium salts such as
Benzyl fatty alkyl dimethyl ammonium chloride with C ₈ -C ₂₂ ,
Benzyl-1,1,3,3-tetramethylbutyl-phenoxyethoxyethylammonium chloride (benzethonium chloride, Hyamin 1622),
Pyridinium compounds such as cetylpyridinium bromide or chloride,
Oxyquinolinium compounds such as oxyquinolinium bromide or chloride.

Furthermore, products of the reaction can be used as ammonium compounds of alkylamine compounds and polyalkyleneamine compounds with Epichlorohydrin are used that are open-chain or ring-shaped can be such. B. of ethylenediamine, diethylaminopropylamine, Tetraethylene pentamine, polyethylene amine, imidazole or hexamethylenetetramine.

Other groups of ammonium compounds are products of the reaction of alkylamino and polyalkylene amino compounds with fatty acids of chain lengths C ₈ -C ₂₂ or with aliphatic dicarboxylic acids with 2-6 carbon atoms, in open chain or ring form, such as, for. B. fatty acid amidoalkyl compounds, fatty acid imidazolinium compounds such as fatty acid imidazolinium acetate, coconut fatty acid dimethylamido propyl betaine compounds, polyamide amine resin formate; further products of ethoxylation and propoxylation of mono-, di- and polyamine compounds such. B. stearylamine ethoxylate, and ammonium compounds of urea, guanidine and hydrazine and their derivatives.

Suitable anions of the ammonium compounds according to the invention are preferably chloride, bromide, sulfate, phosphate, formate, acetate or hydroxide, but other anions are also fundamental usable.

The use of the compounds according to the invention for the reduction The period of body formation is characterized in that already relatively low additions are effective. The improvements will be with amounts up to approx. 1%, based on the solids content of the slip, achieved, but in some cases doses are already around or below 1 ‰ effective. Additions in the range between 0.001% to are preferred apply about 0.5%. This applies to both conventional casting compounds for potting without applying pressure, and in particular for Slips made using the low, medium or high pressure casting process  are processed. The additives can either be liquid slip can be added, or already in the mixing water to produce the slip.

The subject of the invention is illustrated by the following examples 1 to 19 illustrated with table. With the masses used it is standard commercial sanitary materials Composition by the Fuchssche Tongruben company in Ransbach- Baumbach are supplied and known worldwide and are in use, and a standard mass for non-pressurized casting, that as a condenser 0.2% sodium polyacrylate are added ("blank sample I"), and around a mass optimized for die casting, in which as a condenser 0.2% sodium humate silicate can be added ("blank sample II"). From these masses with the named plasticizers were made with water Slurry with a uniform liter weight around 1800 g / l suspension manufactured. These blank samples were additionally marked with the in Examples 2-17 and 19 given drainage aids, either in the mixing water or to the prepared slip. The viscosity of the finished slip was determined using a viscometer according to Lehmann (expiry time immediately and after 10 minutes standing time) and using a rotary viscometer (at 300 rpm from the upward and downward the downward load of the recorded flow curve). The Slips were depressurized in a plaster crucible mold (15 minutes) and using a filter press (pressure 15 bar, 10 minutes) drained, whereupon the thickness of the body thus formed was determined has been.

The measured values of Examples 1 to 19 are shown in the table poses. The values of the body formation in Examples 2 to 17 as well 19 (with the addition of the drainage aids according to the invention) in each case compared with the values of the blank sample I or II and in Percent increase in body formation specified. It shows, that the formation of cullets under the influence of drainage aids is significantly improved. It can be added with 0.05% customary and conventional die casting masses shortening the Cullet formation times in the range of 45% can be achieved.

Example 1 (blank sample I)

A commercial sanitary material (supplied by Fuchs'sche Ton mines, Ransbach-Baumbach) was mixed with 38% mixing water (water content based on the solid) and 0.2% of a polycarboxylic acid salt (Polyacrylic acid sodium) added and homogenized.

Example 2

The prepared slip according to Example 1 was 0.01% reaction product from dimethylaminopropylamine and epichlorohydrin (1: 1) added; with reduced viscosity compared to the blank The formation of cullet was increased by 10.6% when pressure-free casting and 10.1% in die casting.

Example 3

The prepared slip according to Example 1 was 0.03% reaction product from dimethylaminopropylamine and epichlorohydrin (1: 1) added; at the same viscosity compared to the blank, the Cullet formation increased by 53.2% when pressure-free casting and by 26% for die casting.

Example 4

The sanitary composition from Example 1 became 0.01% reaction product Dimethylaminopropylamine and epichlorohydrin (1: 1) during processing added to the mixing water; at reduced viscosity the Shard formation increased by 10.6% when pressure-free casting and by 10.1% in die casting.

Example 5

The sanitary composition from Example 1 became 0.03% reaction product Dimethylaminopropylamine and epichlorohydrin (1: 1) during processing added to the mixing water; at the same viscosity the Cullet formation increased by 53.2% when pressure-free casting and by 26% for die casting.  

Example 6

The prepared slip according to Example 1 was 0.03% reaction product from tetraethylene pentamine and epichlorohydrin (1: 3) added; the formation of cullet was the same increased by 14.9% in non-pressure casting.

Example 7

The prepared slip according to Example 1 was 0.03 reaction product from ethylenediamine and epichlorohydrin (1: 2) added; the body formation was increased by 8.5% in the unpressurized Pour and by 13% in die casting.

Example 8

The prepared slip according to Example 1 was 0.03% reaction product of imidazole and epichlorohydrin (1: 1.7) added; with reduced viscosity, the formation of cullet was increased by 32% in non-pressure casting and by 6.5% in pressure casting.

Example 9

The prepared slip according to Example 1 was 0.03% reaction product from hexamethylenetetramine and epichlorohydrin (1: 2.7) added; body formation increased by 14.9% in unpressurized casting and 6.5% for die casting.

Example 10

The prepared slip according to Example 1 was 0.03% Hyamin 1622 (Benzethonium chloride = benzyldimethyl- (4- {2 [4- 1,1,3,3-tetramethylbutyl) phenoxy] ethoxy} ethyl) ammonium chloride) added; at the same The cullet formation was increased by 25.5% pressureless casting and by 14.5% in die casting.

Example 11

The prepared slip according to Example 1 was 0.03% cetylpyridinium bromide added; with reduced viscosity the fragments maintain education.  

Example 12

The prepared slip according to Example 1 was 0.03% Added N- [3- (dimethylamino) propyl] coconut fatty acid betaine; with reduced viscosity, the formation of cullet was eliminated hold.

Example 13

The prepared slip according to Example 1 was 0.03% Added oxyquinolinium base; at reduced viscosity maintain the body formation.

Example 14

The prepared slip according to Example 1 was 0.03% Added stearylamine ethoxylate; at reduced viscosity the body formation increased slightly.

Example 15

The prepared slip according to Example 1 was 0.03% Guanidine dihydrogen phosphate added; with reduced viscosity the body formation was maintained.

Example 16

The prepared slip according to Example 1 was 0.03% Diguanidine monohydrogen phosphate added; with lowered Viscosities were maintained.

Example 17

The prepared slip according to Example 1 was 0.03% histidine Mono hydrochloride added; at reduced viscosity the Maintain body formation.  

Example 18 (blank sample II)

A commercially available die casting compound (supplied by Fuchs'sche Clay pits, Ransbach-Baumbach) with 40% mixing water and 0.2% liquefier (huminate silicate preparation) added and homogenized.

Example 19

The slip produced according to Example 18 was 0.01% Reaction product from dimethylaminopropylamine and epichlorohydrin (1: 1) added; the cullet was of the same viscosity education increased by 37.5% in non-pressure casting and by 9.6% for die casting.  

Claims (5)

1. Use of organic ammonium compounds in quaternized form in ceramic slip to accelerate drainage during body formation in casting processes. 2. Use according to claim 1, characterized in that ammonium compounds of the general formula
can be used, where R ₁ , R ₂ , R ₃ and R _{4 can} mean:
one or two alkyl radicals C ₄ -C ₂₀ ,
a group of tetramethylbutylphenoxyethoxyethyl,
a benzyl group -CH ₂ C ₆ H ₅ ,
a pyridine or quinoline ring instead of R ₁ + R ₂ + R ₃ ,
and the remaining substituents are hydrogen or alkyl groups with C ₁ -C ₄ ,
and A ^{⊖ is} any anion. 3. Use according to claim 1, characterized in that as ammonium compounds products of the reaction of alkylamine and polyalkyleneamine Compounds with epichlorohydrin are used. 4. Use according to claim 1, characterized in that products of the reaction of alkylamine and polyalkylene amine compounds with fatty acids of chain lengths C ₈ -C ₂₂ are used as ammonium compounds. 5. Use according to claim 1, characterized in that as Ammonium compounds products of the reaction of polyalkylene amine compounds with aliphatic dicarboxylic acids with 2-6 carbon atoms can be used.