CH654756A5 - STABLE SUSPENSIONS OF SODIUM SILICO ALUMINATES. - Google Patents

Description

The subject of the present invention is aqueous suspensions of sodium silicoaluminates, zeolite type, stable to vibrations and to vibrations of transport.

Sodium silicoaluminates have been recommended for the formulation of detergent compositions which can be used, for example, as laundry detergents.

The interest of sodium silicoaluminates in detergency applications lies in their ability to sequester calcium ions in solution. Therefore, they constitute substitutes for sodium tripolyphosphate. They have the advantage of not generating, when they are released into the natural environment, the eutrophication phenomena observed in lakes or watercourses with tripolyphosphate.

The aqueous suspensions of sodium silicoaluminates of the zeolite type are also suitable for the preparation of coating compositions for cellulosic materials.

Among the sodium silicoaluminates, the most favorable is zeolite A with the overall formula Na20-Al203-2Si02-4.5H20. It is characterized by a perfectly defined crystalline system (file N ° 11,590 from JCPDS, International Center Diffraction Data).

Numerous processes for manufacturing zeolite A have been proposed; let us cite in particular those of French patents Nos 2398698 (77.23373) of July 29, 1977 and 2444005 (78.35344) of December 15, 1978.

The industrial product obtained is in the form of a powder with a particle size ranging from 2 to 10 p. (for 95% of the particles) and having a sequestering power of calcium ions greater than or equal to 110 mg Ca per gram of anhydrous product.

This powder can be directly incorporated into detergent mixtures but, since this type of mixture is generally prepared by atomization of an aqueous suspension of all the constituents, it is advantageous to introduce zeolite A not at the state of dry powder, but in the form of a suspension which can be obtained directly in the manufacture of the said zeolite, after the filtration and washing operations. This eliminates a drying operation.

French Patent No. 2287504 (75.30402 of October 3, 1975} described the preparation of suspensions of zeolite A and their use in the preparation of washing and cleaning products. Such suspensions, the anhydrous content of which can reach 42% by weight, are suitable for being pumped by industrial pumps of current model; they can be stored for relatively long periods without exhibiting settling phenomena. However, it has been found that these suspensions, when subjected to regimes of trepidation and vibration as it occurs during transport (in particular in road tanks), do not have sufficient stability to avoid a partial settling of the suspended solids. Hence a clogging of the pipes provided for the transfers.

However, it has been found, in the licensee's services, that it is possible to obtain suspensions having an anhydrous content of up to 50% by weight, the stability of which is sufficiently improved to prevent any start annoying settling during transport. Furthermore, the viscosity of these suspensions can be adjusted in a range of between 0.100 and 5,000 Pa-s, preferably between 0.300 and 3,000 Pa-s, which facilitates the choice of industrial pumps to be used during transfer operations.

The suspensions according to the invention consist of the following elements:

- 40 to 50% by weight of anhydrous sodium silicoaluminate, preferably 43.5 to 47.5% by weight;

- 0.4 to 2.5% by weight of a nonionic surfactant of the macromolecular polymer organic compound type carrying hydroxyl groups;

- 0.03 to 0.40% by weight of an alkali metal oxide, preferably 0.10 to 0.30%, present in the form of hydroxide;

- 50 to 60% water;

- optionally, 20 to 200 parts per million by weight of a bactericidal agent.

The macromolecular polymeric organic compound carrying hydroxyl groups can be a natural and / or synthetic compound such as polyethylene oxides and the polysaccharides obtained by treatment of natural cellulose or starches of cereals or potatoes; as such, one can cite Amijel 12014 which is a native corn starch manufactured by the Company of corn products ("Starches in stationery", S.P.M., 03.80).

The bactericidal agent is intended to prevent bacterial degradation of the surfactant. Advantageously, formaldehyde is used.

The suspensions according to the invention are prepared by mixing the constituents at room temperature with stirring; the following examples are given without limitation.

Example 1

83.6 kg of a zeolite A cake as obtained industrially after filtration and washing and containing 78% by weight of dry matter and 0.20% of caustic Na 2 O (i.e. 0.25% relative to the zeolite crystallized at 4.5 mol of water) are suspended in 43 kg of 5% solution of Amijel 12014. This gives 126.6 kg of suspension containing:

51.5% of zeolite A. i.e. 40% in anhydrous matter 1.7% of Amijel 12014 0.13% of Na20 in the hydroxide state

46.7% water.

This suspension has a Brookfield viscosity of 800 cPo. By means of a common type industrial pump, for example a PCM pump manufactured by the company Moyneau, this suspension is transferred into a cylindrical tank 500 mm in diameter, 1150 mm in height and fitted with a tube at its bottom. lateral diameter 50 mm.

This tank is placed on a truck and transported over a distance of at least 1000 km traveled in a total time (including stops) of approximately 48 h.

5

io

15

20

25

30

35

40

45

50

55

60

65

3

654756

The transfer is carried out without difficulty. On the other hand, there is no settling in the tank; the suspension has retained all of its rheological properties.

Example 2

70 kg of powdered zeolite A containing 0.19% Na, 0 caustic are suspended in 46 kg of Amiel 12014 solution at 3.8%. A suspension is thus obtained containing: 60.1% of zeolite A, or 47.5% in anhydrous material 1.5% of Amijel 12014 0.11% of Na 2 O in the hydroxide state 38.29% of water and having a viscosity of 0.620 Pa-s.

This suspension is subject to the conditions of transfer and transport described in Example 1. It is found that the suspension has retained all of its rheological properties.

The compositions according to the invention thus have good mechanical stability and a sufficiently low viscosity to be able to be transferred without special difficulties.

These advantageous properties result, as has been observed, from a phenomenon of synergy of the couple of surfactant / oxide of - alkali metal in the state of hydroxide. The fact is highlighted in Table I.

Table I

Table II makes it possible to make a comparison between suspensions according to the invention comprising different surfactants (examples 6, 7, 9-13), on the one hand, and suspensions devoid of surfactant (examples 3, 4, 5) or whose characteristics are outside the limits of the invention (Example 8), on the other hand.

Table II

Composition of the suspension (g)

Properties of the suspension.

Zeolite A at 4.5 mol h2o

Aqueous phase

Amijel 12014

Na20

Water

Viscosity Pa-s

Stability

0

1.37

0

0.10 0.17 0.34

43.63 43.53 43.46 43.29

0.024 0.400 0.350 0.270

55

0

0.10 0.17 0.34

44.90 44.83 44.66

0.015 0.027 2,400

bad bad bad

1.37

0.10 0.17 0.34

43.53 43.46 43.29

0.760 3.600 6.400

good good good

Ex.

Surfactant (% by weight)

Na20 (% by weight)

Brookfield viscosity (cPo)

Stability

3

0

0.10

15

bad

4

0

0.17

27

bad

5

0

0.35

2400

bad

polyethylene oxide

(Polyox WSR 301)

6

0.4

0.03

4500

good

hydroxypropyl-

methyl cellulose

(Methocel K 15M)

7

0.4

0.11

3000

good

Native starch from

corn (Amijel 12014)

8

0.35

0.025

120

bad

9

0.35

0.40

4000

good

10

1.10

0.10

450

good

11

1.10

0.17

3250

good

12

1.37

0.10

760

good

13

1.37

0.17

3600

good

15

20

25

30

R

Claims (7)

654,756 1. Stable aqueous suspensions of sodium silicoaluminate, characterized in that they have a viscosity of between 0.100 and 5,000 Pa-s and comprise, relative to the suspension, 40 to 50% by weight of anhydrous sodium silicoaluminate, 0, 4 to 2.5% by weight of a nonionic surfactant of the macromolecular polymer organic compound type carrying hydroxyl groups, 0.03 to 0.40% by weight of an alkali metal oxide, present in the hydroxide state, and 50 to 60% by weight of water. 2. Suspensions according to claim 1, characterized in that they further comprise a bactericidal agent. 2 3. Suspensions according to claim 1, characterized in that they preferably comprise 43.5 to 47.5% by weight of anhydrous silicoaluminate and 0.10 to 0.30% of alkali metal oxide present in the d state 'hydroxide. 4. Suspensions according to claim 1, in which the sodium silicoaluminate is a zeolite A having a sequestering power of calcium ions equal to or greater than 110 mg of calcium per gram of anhydrous zeolite, the particles of this zeolite being essentially particles of 2 at 10 days. 5. Suspensions according to claim 1, in which the alkali metal oxide is sodium oxide. 6. Suspensions according to claim 1, in which the surfactant is a polyethylene oxide or a cellulosic polysaccharide. 7. Suspensions according to claim 2, in which the bactericidal agent is formaldehyde.