DE19601063A1 - Crystalline layered sodium silicate - Google Patents

Description

The invention relates to a crystalline layered sodium silicate, a process for its production lung and its use.

The various known crystalline sodium silicates can be distinguished from one another by their Composition as well as by their respective specific X-ray diffraction pattern below divorce. Often a sodium silicate with unchanged composition can be used with un different crystal structures. The individual forms differ in general in their physical and chemical properties of each other. One of The most important synthetic layered sodium silicate is the δModifi cation of sodium disilicate, the so-called SKS-6 or δ-Na₂Si₂O₅, which is high Has ion exchange capacity for calcium and magnesium ions and especially for Water softening is used (EP-A-0 164 514).

An important parameter for measuring the ion exchange capacity and for characterizing the layered silicates is the lime binding capacity (KBV), which specifies with a defined measuring method how much calcium ions the layered silicate can bind in aqueous solution. It is very important that this ion exchange capacity is available as quickly as possible after adding the layered silicate to water. The KBV values for the individual Na₂Si₂O₅ modifications or mixtures thereof are usually between 30 and 80 mg Ca ²⁺ / g layered silicate.

The production of crystalline sodium disilicates with a layer structure is different possible ways. According to DE-A-31 00 942 one obtains by tempering sodium silicate glasses or by heating sodium carbonate with quartz crystalline sodium salts of silicas with an SiO₂ / Na₂O ratio of 2: 1 to 3: 1.  

DE-A-34 17 649 describes a process for the preparation of crystalline sodium silicate Kate with a molar ratio of SiO₂ / Na₂O of 1.9: 1 to 3.5: 1 from amorphous Natri silicate, whereby water-containing amorphous sodium silicate is mixed with seed crystals, the reaction mixture is dewatered by heating and the dewatered reaction mixture as long as at a temperature that is at least 450 ° C, but below that Melting point is until the sodium silicate has crystallized. This method can be used produce the α, β, γ and δ modifications of Na₂Si₂O₅.

Willgallis and Range (Glastechn. Ber. 37 (1964), 194-200) describe the production of α-, β- and γ-Na₂Si₂O₅ by tempering melted and unmelted dewatered soda water glass. These products have a layered structure; from the x-rays diffractograms result in the crystalline form. Depending on the temperature the various crystal modifications mentioned above can be obtained. The Her However, δ-Na₂Si₂O allerdings is not possible using this method.

DE-A-41 42 711 describes a process for the production of crystalline sodium disis Liquids with a layered structure by reacting sand with sodium hydroxide solution and spray drying the water glass solution thus obtained, whereby the spray-dried, powdered Amorphous sodium disilicate is ground, placed in a rotary kiln and in it at tempera tures from 400 to 800 ° C up to an hour with the formation of crystalline sodium disili Kat treated.

EP-A-0 550 048 describes an inorganic ion exchange material that corresponds to the formula x M₂O · y SiO₂ · z M'O and where M = Na or K, M '= Ca or Mg is with y / x = 0.5 - 2.0 and z / x = 0.005 - 1.0. From the other information in this document is too deduce that it is very alkali-rich silicates with chain structure, but often Obviously, they cannot be kept phase-pure.

Finally, Japanese Patent Laid-Open Hei 4-160 013 describes a method for Production of types of δ-sodium disilicate by using a boron-containing compound with egg ner aqueous solution of an alkali metal silicate with a molar ratio SiO₂ / M₂O (M = alkali metal) is mixed from 1 to 3 and then dried and calcined  becomes. The yield and crystallinity of the product is mainly related to the ratio SiO₂ / M₂O controlled.

A disadvantage of the known methods is that they either do not become a product at all the composition Na₂Si₂O₅ lead or that the particularly advantageous δ modification is not obtained in high yield, but with α-, β- and γ-Na₂Si₂O₅ is contaminated.

In particular, there is a need for crystalline layered sodium silicate with an increased ion exchange capacity for Ca ²⁺ ions in aqueous solution.

It was therefore an object of the invention to provide a crystalline layered sodium silicate which, in particular, has an increased ion exchange capacity with respect to Ca ²⁺ ions. Preferably, the calcium binding capacity should assume the highest possible value shortly after adding the layered sodium silicate to water.

This object is achieved by a crystalline layered sodium silicate according to claim 1 with the formula x Na₂O · ySiO₂ · zP₂O₅, in which
the ratio x to y of a number from 0.35 to 0.6,
the ratio x to z of a number from 1.75 to 1200
and the ratio y to z corresponds to a number from 4 to 2800.

In the aforementioned formula, the ratio x to y preferably corresponds to a number of 0.40 to 0.57, x to z a number from 8 to 400 and y to z a number from 20 to 800.

Particularly preferably, x to y corresponds to a number from 0.45 to 0.55, x to z corresponds to a number of 15 to 200 and y to z a number from 40 to 400.

In particular, the last-mentioned compositions lead to layered sodium silicates according to the invention with high crystallinity and a very high calcium binding capacity of more than 85 mg Ca ²⁺ / g sodium layer silicate, preferably of more than 90 mg Ca ²⁺ / g sodium layer silicate.

KBV values of more than 100 mg Ca ²⁺ / g sodium sheet silicate can be achieved regularly with the sodium sheet silicates according to the invention.

There is also a need for a simple method to achieve the aforementioned, fiction, moderate crystalline sodium layer silicates in a wide temperature range with as much as possible crystallize high yield.

This object is achieved by a method for producing a crystalline sodium Layered silicate of the general formula x Na₂O · ySiO₂ · zP₂O₅, in which the x, y and z are have standing meaning, which is characterized in that one phosphorus-containing compound in an aqueous medium with a silicate compound mixes, brings to reaction, partially dewatered and then calcined.

Suitable phosphorus-containing compounds are those of the general formula H _{n + 2} P _n O _{3n + 1} (n = 1 to 6), H _n P _n O _3n (n = 3 to 8) and HPO₃ and their alkali metal salts and / or diphosphorus pentoxide Question.

Silicate, for example silica, silica gel, sodium silicate and / or quartz sand can be used.

The partial drainage of the mixture of the phosphorus-containing compound and the aq The solution of the silicate compound takes place at 80 to 300 ° C., preferably at 105 to 220 ° C. and leads to amorphous, water-containing products, the loss on ignition (720 ° C, 1 h) between Chen 1 and 22 wt .-%.

The process according to the invention is carried out at 560 to 840 ° C., preferably at 600 to 780 ° C. calcined.

The time for the calcination is not critical, it is generally 0.5 to 5 Hours.

The layered sodium silicates according to the invention are outstandingly suitable for softening of water containing calcium and / or magnesium ions.  

Likewise, the layered sodium silicates according to the invention can be used in many fields of application Builder can be used.

The layered sodium silicates according to the invention find their preferred use in Detergents and cleaning agents.

In addition to its excellent primary washing action, a ver improved secondary washing effect. This is particularly evident in a significantly reduced th incrustation of the washed with the layered sodium silicate according to the invention Fabric.

In the following examples, in which the invention is described in more detail, the Lime binding capacity of the crystalline sodium disilicates obtained was determined as follows:

Method 1

30 g of a calcium solution (131.17 g CaCl₂ · 2H₂O are dissolved in distilled water and made up to 5000 g) with 5.6 g of a buffer solution (75.07 g glycine and 58.4 g NaCl are dissolved in distilled water and made up to 1000 ml) and mixed with distilled water to 999 g. This solution, which has a water hardness of 30 ° dH or corresponds to 300 mg CaO / 1, is tempered to 20 ° C and mixed with 1 g sample. The Solution was stirred for a certain time (e.g. 10 minutes), filtered off and in the filtrate the calcium remaining in the solution is determined complexometrically. By difference bil With the original calcium content, the calcium binding capacity, general my designated KBV value.

Method 2

The calcium stock solution consists of 157.30 g CaCl₂ · 2H₂O, which in distilled water dissolved and made up to 1000 ml. 88.5 g are used to prepare the buffer solution Glycine and 69.04 g NaClu dissolved in 520 ml 1 N sodium hydroxide solution and with distilled water Replenished 2000 ml.  

980 ml of distilled water, 20 ml of buffer solution and a total of 5 ml of calcium stock solution are mixed and tempered to 20 ° C. The resulting water hardness corresponds if 30 ° dH. After adding 1 g of sample substance, the unbound calcium concentrate tration with the help of an ion-sensitive electrode (e.g. from ORION, model 900 200) continuously detected. As a measure of the speed of water softening will follow in the the examples the KBV value after 1 and after 3 minutes.

The primary washing action of the textile detergent was carried out at 60 ° C on various test machines weave determined according to DIN 53 919 by determining the reflectance difference, which from the difference in the reflectance of the test fabric after and before washing. The Secondary washing was also carried out on various test fabrics at 60 ° C DIN 53 919 determined.

example 1

A stirred autoclave - with a total volume of 0.25 l and equipped with Teflon inliner - was used 230 g of a mixture of 113.6 g of sodium hydroxide solution (50% by weight), 13.57 g of Na₃PO₄ · 12 H₂O, 88.8 g silica (Wacker HDK T30) and 60 g distilled water filled to 200 ° C (corresponding to approx. 15 bar) and kept at this temperature for 90 minutes. The product was removed, spray dried and then at 720 ° C for one hour calcined. According to analysis, the end product contains 8100 ppm phosphorus. With the help of X-ray diffraction diffraction pattern shows the phosphorus-containing product as a meta interpret stable δ-modification of Na₂Si₂O₅ analog layered silicate.

The lime binding capacity of the product was determined according to Method 1 to be 101 mg Ca ²⁺ / g. According to method 2, a KBV value of 98 mg Ca ²⁺ / g after 1 minute or 98 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 2

The procedure was analogous to Example 1, but the calcination temperature corresponded Table 1 was varied. The X-ray diffraction patterns of phosphorhalti Products can be compared with the data of the various known literature  Interpret modifications of Na₂Si₂O₅. An estimate of the X-ray determined phase compositions and the KBV values of the phosphorus-containing Layered silicates are also listed in Table 1.

Example 3 (comparative example)

The procedure was analogous to Examples 1 and 2, but the approach was none Phosphorus compound added. The results are shown in Table 2 remove.

Example 4

A stirred autoclave - with a total volume of 0.25 l and equipped with Teflon inliner - was used 230 g of a mixture of 113.6 g of sodium hydroxide solution (50% by weight), 27.13 g of Na₃PO₄ 12 H₂O, 96.6 g silica (Wacker HDK T30) and 45 g distilled water filled to 200 ° C (corresponding to approx. 15 bar) and kept at this temperature for 90 minutes. The product was removed, spray dried and then at 720 ° C for one hour calcined. According to analysis, the end product contains 14500 ppm phosphorus. The Röntgenbeu The diffraction pattern of the phosphorus-containing product can be described as a δ-phase analog Interpret layered silicate.

The lime binding capacity of the product was determined according to Method 1 to be 104 mg Ca ²⁺ / g. According to method 2, a KBV value of 104 mg Ca ²⁺ / g after 1 minute or 102 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 5

The procedure was analogous to Example 4, but the calcination was carried out at 700.degree was led. The X-ray diffraction pattern of the product containing phosphorus leaves largely interpret itself as a δ-phase-analogous layered silicate. The share of kri stallinen low temperature modification (β phase) is less than 25%; an α-phase analog High-temperature modification cannot be demonstrated by X-ray analysis.

The lime binding capacity of the product was determined according to Method 1 to be 113 mg Ca ²⁺ / g. According to method 2, a KBV value of 114 mg Ca ²⁺ / g after 1 minute or 114 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 6

A stirred autoclave - with a total volume of 0.25 l and equipped with Teflon inliner - was used 230 g of a mixture of 113.6 g of sodium hydroxide solution (50% by weight), 1.60 g of Na₃PO₄ · 12 H₂O, 86.6 g silica (Wacker HDK T30) and 60 g distilled water filled to 200 ° C (corresponding to approx. 15 bar) and kept at this temperature for 90 minutes. The product was removed, spray dried and then at 720 ° C for one hour calcined. According to analysis, the end product contains 995 ppm phosphorus. The Röntgenbeu The diffusion diagram of the phosphorus-containing product can be described as a δ-phase analog Interpret layered silicate.

The lime binding capacity of the product was determined according to Method 1 to be 104 mg Ca ²⁺ / g. According to method 2, a KBV value of 104 mg Ca ²⁺ / g after 1 minute or 102 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 7

A stirred autoclave - with a total volume of 0.25 l and equipped with Teflon inliner - was used 230 g of a mixture of 116.4 g of sodium hydroxide solution (50% by weight), 2.05 g of phosphoric acid (85%), filled with 86.6 g of silica (Wacker HDK T30) and 60 g of distilled water  200 ° C (corresponding to about 15 bar) heated and ge for 90 minutes at this temperature hold. The product was removed, spray dried and then at one hour Calcined at 720 ° C. According to analysis, the end product contains 4500 ppm phosphorus. The X-ray Diffraction pattern of the phosphorus-containing product can largely be considered as a interpret δ-phase-analogous layered silicate; the proportion of the α phase is below 10%.

The lime binding capacity of the product was determined according to Method 1 to be 98 mg Ca ²⁺ / g. According to method 2, a KBV value of 98 mg Ca ²⁺ / g after 1 minute or 99 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 8

The procedure was analogous to Example 7, but the calcination was carried out at 680 ° C was led. The X-ray diffraction pattern of the product containing phosphorus leaves largely interpret itself as a δ-phase-analogous layered silicate. The share of kri stallinen low-temperature modification (beta phase) is well below 50%; an alpha phase naloge high temperature modification can not be proven by X-ray.

The lime binding capacity of the product was determined according to Method 1 to be 108 mg Ca ²⁺ / g. According to method 2, a KBV value of 114 mg Ca ²⁺ / g after 1 minute or 114 mg Ca ²⁺ / g after 3 minutes can be determined.

Example 9

The detergent formulations were prepared in accordance with Table 3 from the various individual components by the spray mixing method familiar to the person skilled in the art. For comparison purposes, a commercially available crystalline layered sodium silicate (SKS-6, Hoechst AG; limescale binding capacity according to Method 1 of 82 mg Ca ²⁺ / g) was used in formulation A. Formulation B contains a sodium silicate layer according to the invention with 8100 ppm phosphorus (α phase <10%, β phase <15%, δ phase <75%; lime binding capacity according to method 1 of 104 mg Ca ²⁺ / g). It should be noted that no polycarboxylates were added to the formulations in order to better assess the incrustation behavior.

The washing tests were carried out with a dosage of 65 8 washing powder per wash a total water hardness of 18 ° dH (ratio Ca: Mg = 5: 1) and a temperature of 60 ° C. The washing machines were loaded with 3.75 kg Dry wash.

Table 4 shows the results of the primary washing performance and Table 5 shows the results of the incrustation behavior.  

Table 3

Composition of the detergent formulations (in% by weight)

Table 4

Primary washing performance (in% remission difference)

Table 5

Incrustation behavior (in% ash after 25 washes)

Claims (19)

1. Crystalline layered sodium silicate of the general formula xNa₂O · ySiO₂ · zP₂O₅in the
the ratio x to y of a number from 0.35 to 0.6,
the ratio x to z of a number from 1.75 to 1200
and the ratio y to z corresponds to a number from 4 to 2800. 2. Crystalline layered sodium silicate according to claim 1, characterized in that
Ratio x to y a number between 0.4 to 0.57, the ratio x to z a number from 8
to 400 and the ratio y to z corresponds to a number from 20 to 800. 3. Crystalline layered sodium silicate according to claim 1, characterized in that the Ratio x to y a number from 0.45 to 0.55, the ratio x to z a number from 15 to 200 and the ratio y to z corresponds to a number from 40 to 400. 4. Crystalline layered sodium silicate according to at least one of claims 1 to 3, characterized in that it has a lime binding capacity of at least 85 mg Ca ²⁺ / g layered silicate. 5. Crystalline layered sodium silicate according to claim 4, characterized in that it has a lime binding capacity of at least 90 mg Ca ²⁺ / g layered silicate. 6. Process for the preparation of a crystalline layered sodium silicate of the general form mel x Na₂O · y SiO₂ zP₂O₅, in which x, y and z have the meaning given in claim 1 tion, characterized in that a phosphorus-containing compound in egg nem aqueous medium mixed with a silicate compound, reacted, partially watered and then calcined. 7. The method according to claim 6, characterized in that the phosphorus-containing connec tion of the general formula H _{n + 2} P _n O _{3n + 1} (n = 1 to 6), H _n P _n O _3n (n = 3 to 8) and HPO₃ and their alkali salts and / or diphosphorus pentoxide. 8. The method according to claim 6, characterized in that the silicate compound Kie is silica, silica gel, soda water glass or quartz sand. 9. The method according to at least one of claims 6 to 8, characterized in that is partially dewatered at 80 to 300 ° C. 10. The method according to claim 9, characterized in that partially at 105 to 220 ° C. is watered. 11. The method according to at least one of claims 6 to 10, characterized in that the loss on ignition of the amorphous products at 720 ° C and 1 hour annealing time between 1 and Is 22% by weight. 12. The method according to at least one of claims 6 to 11, characterized in that is calcined at 560 to 840 ° C g. 13. The method according to claim 12, characterized in that at 600 to 780 ° C calci is renated. 14. The method according to at least one of claims 8 to 13, characterized in that Is calcined for 0.5 to 5 h.   15. The method according to at least one of claims 8 to 14, characterized in that is partially dewatered by spray drying. 16. The method according to at least one of claims 8 to 14, characterized in that is partially dewatered using a drying oven. 17. Use of the crystalline layered sodium silicates according to claims 1 to 5 or prepared by the method of claims 6 to 16 for the softening of water, the Contains calcium and / or magnesium ions. 18. Use of the crystalline layered sodium silicates according to claims 1 to 5 or produced according to the method of claims 6 to 16 as a builder. 19. Use of the crystalline layered sodium silicates according to claims 1 to 5 or produced by the processes of claims 6 to 16 in washing and cleaning agents teln.