FR2461516A1 - STABLE SUSPENSIONS OF ZEOLITES IN WATER - Google Patents

Abstract

THE SUBJECT OF THE INVENTION IS STABLE SUSPENSIONS OF ZEOLITES IN WATER, HAVING GOOD RHEOLOGICAL PROPERTIES, CHARACTERIZED IN THAT THEY CONTAIN FROM 0.01 TO 0.50, IN PARTICULAR FROM 0.05 TO 0.20 BY WEIGHT, IN RELATION TO SUSPENSION, OF A STABILIZER CONSISTING OF A METHACRYLIC ETHYLEACID ACRYLATE COPOLYMER, AND QUANTITIES OF ANHYDROUS ZEOLITE SIZING BETWEEN 42 AND 56, IN PARTICULAR BETWEEN 48 AND 54 BY WEIGHT, RELATED TO SUSPENSION.

Description

1.

  The present invention relates to static suspensions

zeolite in water.

  According to British Patent No. NP 1 529 713, it is known that

  dissolving in the deionized water a polymer of the acrylic acid

  by adding a zeolite, we obtain suspen-

  which can be conserved without risk of sedimentation.

  and have a sufficiently low viscosity to be transferred and pumped even after long periods of storage. According to this same patent, it can be assumed that the amount of stabilizer should be between 0.5 and

  6% by weight, relative to the suspension, and that the weight

  the stabilizer is relatively weak; in fact, a molecular weight of about 20,000 is suggested for polyacrylic acid. The amounts of stabilizer indicated in FIG.

  patent mentioned above are far from negligible.

  The present invention proposes to prepare suspensions

  stable concentrations of zeolites in water, with good

  rheological techniques, using very small amounts of stabilizers; other objects of the invention will emerge from the

description that will follow.

  According to its most general aspect, the present invention aims at stable suspensions of zeolites in water, endowed with good rheological properties and which are characterized by the presence of amounts ranging between 0.01 and 0.50%, preferably between 0.05 and 0.20% by weight, relative to the

  suspension, a stabilizer consisting of a copolymer of

  ethyl crylate and methacrylic acid, having a moderate weight

  between 100 000 and 106, preferably between 500 000 and 106, and amounts of anhydrous zeolite varying between

  42 and 56%, preferably 48 to 54% by weight, based on

port to the suspension.

  This copolymer may have an intrinsic viscosity in the

dimethylformamide of 1.1 to 1.2.

  It is possible to use as stabilizer said copolymer such

  which, or the product obtained by neutralization of this copo-

lymere with caustic soda.

  2. In other words, it is surprising that using said copolymer and large amounts of zeolite, the suspensions are more stable and less viscous, although the amount of stabilizer is much lower than the doses used so far. . The stable suspensions according to

  This invention may contain up to 70% by weight of zeolite

  lite A of the general formula: Na 2 O. A1203. 2SiO2. 4.5 H2O, which corresponds to 56% by weight of anhydrous zeolite, without water of crystallization. The

  The presence of the stabilizers according to the invention makes it possible to

  in an extremely simple way, the viscosity of the

  pensions and therefore their rheological characteristics

  during transportation, storage, pumping and known spray-drying operations; in general, the

  The viscosity of the suspensions according to the present invention is

  between 0.100 and 3.5 N. S / m2 in particular between 0.5 and 2 N. S / m2. Because of their high stability, the suspensions according to the present invention can be stored and transported by conventional tank wagons without

  deposits that are difficult to mix with the

  fluid of suspensions; these suspensions may be used

  advantageously to prepare products for use in

  generally to soften the water and especially to

detergent compositions.

  the stable suspensions according to the present invention can

  can be prepared by various methods; for example, it is possible first to add the stabilizer in water and successively the zeolite, or it is possible to synthesize the zeolite in the form of an aqueous suspension, starting from aqueous solutions of aluminate of sodium and sodium silicate, as described for example in the Italian patent application nP19617 A / 79, then directly add the stabilizer to the wet zeolite from the centrifugation which would otherwise be sent to drying, if the amount of water is not enough for the purpose, it can be remedied by a new water supply. This process offers 3.

  the great advantage of avoiding the inconveniences associated with

  powders nipulation. The alkalinity of these suspensions, generally between pH 11 and pH 13, does not affect the degree

stabilization.

  The following non-limiting examples illustrate the invention

  tion. It should be noted that the examples relate to the use of

  type "A" zeolites, but the invention is advantageously applied to other types of zeolites, in particular

  mixtures of type "A" and "X" type zeolites. The di-

  special zeolite strength for suspensions according to

  the present invention must be less than 100 μm, preferably

  less than 3OyVm, and more preferably less than 15> im.

  In particular, an "A" type zeolite having an index

  granulometry equal to or greater than 80 and a

  preferably equal to or less than 3.

  EXAMPLE 1 to 5 The stabilizer is dissolved at room temperature in deionized water, whereupon a selected sample of zeolite A is added with stirring and at room temperature; the resulting suspension is stirred until completely homogenized. It is allowed to sediment at a

  temperature between 20 and 25 ° C in a cy-

  vertical lindrique with a diameter of about 3 cm and filled to a height of 120 mm. The stability of the suspension can be evaluated by the formula: S = (H-h) x 100 H where S is the empirical degree of stability, H is the height of the suspension in the tank (120 mm) and h is the settling height at the end of the test; when h = O,

  the maximum stability is obtained (S = 100%). In the di-

  to tests, different types of zeolite A are used, obtained according to the process described in the Italian patent application 19617 A / 79 in the name of the Demaederesse. The characteristics of the zeolites used in these examples or in the following 4. are the following: zeolite A / I Pormule: Na2O Al 2 O 3 2 SiO 2. 4.5 H2O: crystallinity:

%. (determined by X-rays).

  Exchange capacity: 172 mg of CaO per gram of anhydrous zeolite

  dre (zeolite without water of crystallisation;

  made according to the method described -appar French patent No. 80 001 283, which consists in stirring a suspension of zeolite

  in a solution of CaCl2 for 15 minutes at 22 + 20C).

  Particle size: (determined by means of a "Coulter Counter" type device) Particle size> 15 μm> 84 μm> 6 μm> 4 μm> 2 μm Quantity of particles 1.0% 2.0% 3, 0% 6.5%, 0%

97.0%

  Zeolite A / II Formula and crystallinity: see Zeolite A / I; exchange:

173.5 mg of CaO / g.

  Granulometry:> 15 μm> 10 μm 8 μm 6 μm> 6 μm> 4 μm> 2 μm

power of

1% 2% 3%% 32%% Zeolite A / III

  Pormule and crystallinity: see Zeolite A / I; power of

exchange:

176 mg of CaO / g.

  5. Granulometry:> 15, m 0%> 10 μm 1.5% 8 μm 2.5%> 6 μm 10%> 4 μm 65%> 2 μm 98.5% As stabilizers, the following are used:

  a) A first copolymer, designated PA2, in which the ratio

  Ethyl acrylate / methacrylic acid port equals 65/35

  by weight, the intrinsic viscosity of the copolymer (

  in dimethylformamide) is 1.15, which corresponds to a molecular weight greater than 500,000;

  b) a second copolymer, designated PA1, obtained by neutralization

  The stabilizer is added in the form of a 30% by weight aqueous suspension of a non-aqueous copolymer to a pH of 9 to 10. neutralized. The data and results are summarized

  in Table I; the viscosities of the suspensions are

  with a Brookfield rotation viscometer.

TABLE I

  Example 'Stabil Type Reading eg I Zeolite Type g Deionized water (g) Initial viscosity of suspension (10-3 NS / m2 at 25 ° C) Stability Test period i Nil - A / I 60 40 50 5 days 75% ( ) 2 PA 1 0.09 "60 40 '100 1 day 98.5% 3 PA 1 0.09" 60 40 100 7 days 96% 4 PA 1 0.24 "60 40 720 12 days 100% PA 2 0, 24 "60 40 800 12 days 100% 6 PA 2 0.10 A / II 62 38 240 4 days 99.5% 7 PA 2 0.10" 62 38 240 12 days 97.5% 8 PA 2 0.20 " 62 38 1600 12 days 100% 9 PA 2 2 (**) A / III 620 380 1480 12 days 100% PA 2 2 (**) "620 380 1480 2 months 97.5% (I) The sedimentation layer at the appearance of a consistent mass, absolutely not

  transportable by means of conventional pumps.

(**) = 0.20%.

_ _ ... _ .. .. _., _._,

  rst 0% 6 LA1 tl c7z final S (H - h) x 100 Hi 7.

EXAMPLES 6 to 10

  A fundamental variant is

  previous plots, instead of adding zeolite to water,

  As a stabilizer, the zeolite is first dispersed in deionized water, with stirring and then with stirring.

  the predetermined amount of stabilizer is added.

  The encouraging results shown in Table I suggest the possibility of directly using the

  moist zeolite masses from the production plant

  this avoids drying operations; the possibility

  the real success of this procedure is proven by the examples

following ples.

EXEYIPLE 11

  20 kg of raw material is used as raw material.

  aqueous solution of zeolite A / III having a pH of 11.5 and

  directly from the zeolite synthesis plant, without drying; the dispersion contains about 46% by weight of water (including the water of crystallization of the zeolite) and

  54% by weight of anhydrous zeolite (residue remaining after calcination)

  at 8002C). 40 g of stabilizer are then added.

  PA2 (0.20% by weight relative to the suspension),

  the suspension is mixed and the stability is determined after prolonged rest; the suspension has an initial viscosity of 1.56 N. S / m2 (at 25 ° C.) and a final stability after 12

days, equal to 100% ..

EXAMPLES 12 to 17

  Examples 8 and 11 are repeated,

  diment the suspension containing the stabilizer at different temperatures and for different durations. The following results are obtained: c. Example of temperature Ultimate stability Test period S _ (- h) x 100 H 12 () 39-C 3 days 98.5% 13 (m) 392C 12 "98.5%

14 (**) 392 0 12 "100%

() 80C 3 days 98.5%

16 (*) 820C 12 98.5%

17 (*) 8 0 12 "100%

(m) repetition of Example 8.

(**) repetition of Example 11.

9.

Claims (8)

- CLAIMS -   1 - Stable suspensions of zeolites in water, gifted   good rheological properties, characterized in that   they contain from 0.01 to 0.50%, especially from 0.05 to 0.20% by weight, relative to the suspension, of a stabilizer consisting of an ethyl acrylate / methacrylic acid copolymber, and amounts of anhydrous zeolite lying between 42 and 56%, especially between 48 and 54% by weight, relative to the suspension. 10 - Suspensions according to claim 1, characterized   in that the stabilizer is added in the form of a suspension aqueous solution.   3 - Suspensions according to claim 1, characterized in that the intrinsic viscosity of the copolymer, determined in dimethylformamide solutions, is between 1.1 and 1.2.   4 - Suspensions according to claim 1, characterized   in that the molecular weight of said copolymer is between   100,000 and 106, especially between 500,000 and 106.   5 - suspensions according to claim 1, characterized in that they have a viscosity of between 0.1 and 3.5,   preferably between 0.500 and 2 N.S / m2.   6 - Suspensions according to claim 1, characterized   in that they have a pH of 11 to 13.   7 - Suspensions according to claim 1, characterized in that the zeolite is an "A" type zeolite, having a particle size index equal to or greater than 80 and a fraction   coarse preferably equal to or less than 3.   8 - Suspensions according to claim 1, characterized in that the zeolite is a mixture of zeolites "A" and zeolites "X".   9 - stable suspensions of zeolites in water, having good rheological properties, characterized in that they contain 0.01 to 0.50%, especially 0.05 to 0.20% by weight,   relative to the suspension, a stabilizer obtained by   treatment with caustic soda, copolymer according to   10, and quantities of anhydrous zeolite of between 42 and 56%, in particular between 48 and 54% by weight, compared to the suspension.