CA2059182A1

CA2059182A1 - Copolymers of diallylaminoalkylenephosphonates and unsaturated carboxylic acids

Info

Publication number: CA2059182A1
Application number: CA 2059182
Authority: CA
Inventors: Matthias Krull; Werner Ritschel; Herrmann Hoffmann; Juliane Balzer; Wolfgang Buch
Original assignee: Individual
Current assignee: Hoechst AG
Priority date: 1991-01-12
Filing date: 1992-01-10
Publication date: 1992-07-13
Also published as: NO920134D0; NO920134L; EP0495355A1; JPH04309511A

Abstract

Abstract of the disclosure:

Copolymers of diallylaminomethylenephosphonates and unsaturated carboxylic acids Copolymers obtainable by copolymerization, at tempera-tures above 70°C, of 0.1 to 50 mol % of at least one diallylaminomethylenephosphonate and 99.9 to 50 mol % of an unsaturated carboxylic acid and if appropriate other unsaturated monomers. The copolymers of this type are suitable as an agent for preventing scale formation (scale inhibitor) and as a builder or co-builder in detergents.

Description

HOECHST AKTIENGESELLSCHAFT HOE 91/F 008 Dr.KI/je Copolymers of diallylaminoalkylenephosphonates and unsaturated carboxylic acids In the extraction of oil, water and gas from underground forma~ions, scale formation, i.~e. the precipitation of sparingly soluble salts of the alkaline earth metals, may occur due to mixing of different saline waters in the well hole, variations in temperature and pressure and similar circumstances during extraction. Scale formation can lead, inter alia, to blocked well holes, delivery pipes and pipelines as well as to seized pumps and valves and can cause considerable repair costs.

To prevent scale formation, on the one hand high mole-cular weight polycarboxylic acids (preferably to counter-act alkaline earth metal sulfate) and on the other handlow molecular weight polyelectrolytes, such as amino-methylenephosphonic acids (preferably to counteract alkaline earth metal carbonate3 are added to saline waters in sub6toichiometric amounts in the range from 1 to 100 ppm. It is assumed that for this so-called "threshold effect", the polyelectrolyte is absorbed onto the surfaces of the crystals and in this way interferes with or suppresses further crystal growth.

Aminomethylenephosphonic acids (for axample Dequest, Monsanto) and other low molecular wei~ht polyelectro-lytes, such as, for example, EDT~ and triphosphates, also have a broad practical application in bleaching washing because of their good bonding capacity for calcium and heavy metals. The heavy metals present reduce the stoxage stability of detergent formulations and damage the fibars during bleaching, and they must therefore as far as possible be removed fcr bleaching washing. High molecular weight polycarboxylic acids lRagnetti; Tenside, Surfac-tants, Detergents 1989, 26, 30) are similarly of great importance as co-builders in phosphate-free and -reduced ', ~
; ' , ~ .

detergents. They probably transport water-soluble metal ions, in particular calcium ions, from the aqueous detergent liquor into the water-~insoluble zeolites used as builders here.

The present invention relates to copolymers which combine the properties of these two classes of substance.

(Co)polymerizable phosphonic acid derivatives are acces-sible by a Mannich reaction of (di~allylamines with aldehydes and phosphorous acid (R. Moedritæer, R.R.
Irani, J. Org. Chem. 1966, 31, 1603).
Homopolymers of diallylaminomethylenephosphonic acid can be employed in flame retardant woven fabrics (JP 76 07,214) and as a complexing reagent for zinc ions (JP
78 19,921). However, like their high molecular wei~ht copolymers with unsaturated carboxylic acids, they have no effect as a scale inhibitor in saline waters or as a builder or cobuilder in detergents. The polyelectrolyte poly(diallyldimethylammonium chloride) which is acces-sible in a similar manner is used, inter alia, as a flocculating agent (C. Wandrey et al.; Wasserwirtschaft 1984, 8, 185).

Copolymers of diallylaminomethylenephosphonic acid and other unsaturated monomers, such as, for example, acrylic acid, acrylic acid esters or acrylic acid amides, have already been described in Japanese Laid-Open Specifica-tion 50-72,987. The copolymers are prepared by polymer-ization at temperatures up to 70C. Because of this relatively low polymerization temperature, these copoly-mers have a relatively high molecular weight. However, such products cannot be used as a scale inhibitor.

It has now been found that those copolymers based on diallylaminomethylenephosphonic acids ale considerably more active as scale inhibitors if the molecular weiyht of the copolymers is lower (K values in the range from 10 to 100, intrinsic viscosity measured by the ~bbelohde .
-I'J ~ ~3~ l;l J

method) than that of the copolymers of Japanese Laid-Open Specification 502,987. This lowering of the molecular weight is achieved by increalsing the polymeri~ation temperature and/or addition of a regulator to the poly-merization system.

The invention thus relates to copolymers having a low average molecular weight corresponding to an intrinsic viscosity of 10 to 100 (measured by the Ubbelohde method) of 0.1-50 mol %, preferably 1-15 mol ~, of at least one diallylaminomethylenephosphonate of the formula Ia or Ib (CH2=CH-CH2)2N~(Rl)-CHR2-PO3M-, (Ia) (CH2=CH-CHz)2N-CHR2-PO3M2 (Ib) in which R1 is hydrogen, C1- to C22-, preferably C1- to C4-alkyl, phenyl or C2- to C4-alkenyl, R2 is hydrogen, Cl-to C4-alkyl or phenyl and M is hydrogen, a cation, such as Na , X+ or NH4~, Cl- to C4-alkyl or benzyl, and 99.~-50 mol %, preferably 99-85 mol %, of at least one ethylenically unsaturated carboxylic acid of the formula II

R3R4C=CR5y (II) in which R3 is hydrogen or a group of the formula COOM, R4 is hydrogen, phenyl or a group of the formula COOM, Rs is hydrogen, methyl or a group of the formula COOM or CH2COOM, Y is a group of the formula COOM, or R4 and R5 together are a C4-alkylene radical, or R4 and Y together are a group of the formula -C(O)-O-C(O)-, or R5 and Y
together are a group of the fonmula -CH2-C(O)-O-C(O)-, and M is hydrogen or a cation, and 0 to 10 mol % of other ethylenically unsaturated monomers.

Examples which may be mentioned of the monomers of the formula Ia~Ib are diallylaminomethylenephosphonic acid, diallylaminoethylenephosphonicacid,diallylaminobenzyli-, ,~
-denephosphonic acid and diethyl diallylaminomethylene-phosphonate, and examples which may be mentioned as representative of comonomers of the formula II are acrylic acid, methacrylic aci~d, maleic acid, maleic anhydride, itaconic acid and cinnamic acid, as well as lower alkyl esters thereof, such as methyl acryla~e and methyl methacrylate. According to the invention, however, other ethylenically unsaturated monomers can also addi-tionally be employed, such as, for example, vinylsulfonic acid, vinylphosphonic acid, vinylpyrrolidone, acrylamide and N- and N,N-substitution products thereof, such as N-methylacrylamide or 2-acrylamido-2-methylpropanesulfonic acid, and also allyl compounds of the formula III
Rl' (CH2=CR6-CH2)"--N l--(Rl )b X' ~III) I

R' .
in which Rl, R1 and Rl independently of one another have the meanings given above for Rl or are tha group CHR2-PO3M2, M is hydrogen, a cation or Cl- to C4-alkyl or phenyl, R6 is hydrogen or methyl, a is 1 or 2, b is 0 or 1, a+b is 2 and X- is an ~nion of an organic or inorganic acid, such as Cl-, Br~, HS04- or CH3C00-, in particular allylamino-bis(methylenephosphonic acid) and allylamino-benzylidenephosphonic acid. The preferred amount of these comonomers here is between 0.001 and 10 mol %.

The copolymers according to the invention of diallyl-aminophosphonates are prepared by polymerizing compounds of the formula Ia or Ib, which can be contaminated, if appropriate, with neutralization salts, such as sodium sulfate or sodium chloride, and compounds of the formula II and if appropriate other ethylenically unsaturated compounds in water and~or in water-miscible organic solvents, preferably at temperatures above 70C, u~ing a free radical chain initiator, for example ammonium peroxodisulfate, hydrogen peroxide or tert-butyl ~:

.

hJ ~

hydroperoxide. The compounds of the formula Ia/Ih and also other comonomers which are added if appropriate (for example those of the formula III) can be either initYally introduced in the aqueous solution or added to the reaction vessel together with the compounds of the formula II. The total monomer concentration is preferably 1 to 60% by weight, and preferably 10 to 60~ by weight.
If the compounds here are water-in~oluble diallylaminomethylenephosphonic acids, they can be converted into their alkali metal or ammonium salts beforehand. The free radical initiator, if appropriate dissolved in a suitable solvent, can be added to the reaction vessel at the same tLme as or after the compounds of the formulae Ia/Ib and II.

The achievement of a low molecular weight, which is important for the use according to the invention, can be influenced favorably by polymerization above 70~ and/or by the use of lower alcohols (C1-C5) as the solvent and/or also by addition of 0.001 to 50% by weight of known regulators, such as thioglycolic acid or dodecanethiol, to the reaction batch. The % by weight relates to the monomers. The intrinsic viscosity X (determination by the ~bbelohde method) of the polymer~ is between 10 and 100, in particular between 10 and 50.

One variant of the process is the polymeri~ation of oil-soluble diallylaminomethylenephosphonic acid dialkyl esters with oleophilic comonomers in organic ~olvents using free radical initiators such as AIBN or organic peroxides. Subsequent hydrolysis of the ester and anhyd-ride groups and removal of the organic solvent by distil-lation gives polymers according to the invention. Suit-able comonomers here are, inter alia, acrylic acid, maleic anhydricle and vinyl aceta-te, and preferred sol-vents are aromatic, aliphatic and also halogenated hydrocarbons.

Depending on the intended use, the viscous polymer .~ ~

,, ~ : ~ .
.
..

~3;s~

solutions are brought to the desired pH with bases, diluted or spray-dried. The copolymers according to the invention are attributed the ~eneral formula T - CH - CH ~ ~ i ~ ;
CH2~ + CH2 ~ LR4 Y J

hardly any crosslinking and Eormation of insoluble structures consequently occurs.

In saline formation waters, the copolymers according to the invention lead to effective inhibition both of alkaline earth metal carbonate deposits and of alkaline earth metal sulfate deposits. At the same time, they have an anticorrosion action. They can furthermore be used as complexing agents for alkaline earth metals and heavy metals, and because of their outstanding dispersing action on calcium carbonate, as builders and co-builders in detergents.

The invention will be illustrated in more detail with the aid of the following examples.

Examples The percentage data are to be understood in all cases as percentages by weight. The water used in the examplss is deionized. The intrinsic viscosity values R were deter-mined by the Ubbelohde method.
The pol~merizations were carried out in 1 1 5-necked flasks with ground glass lids. The flasks are fitted with an anchor stirrer, thermometer, reflux condenser, gas inlet tl~be and dxopping funnel. The solutions initially introduced for the polymerization were flushed wi~h nitrogen.

- . :

, .. ' . ~: ' .. ' .' ' , r Example 1 Preparation of a copolymer of acrylic acid and 5~ of diallylaminomethylenephosphonic acid 2.5 g of diallylaminomethylenephosphonic acid are dissolved in 100 g of water and 20 g of isopropanol and ~he solution i6 heated to 75Cr while passing in a stream of nitrogen. A catalyst solution consisting of 1.5 g of (NHd)2S208 in 30 g of water, and 47.5 g of acrylic acid;
are synchronously added dropwise from 2 dropping funnels at this temperature. When the exothermic reaction phase has ended, the mixture is subsec~ently stirred at 80C
for 4 hours. The colorless 25% strength polymer solution has an intrinsic viscosity K of between 20 and 25.

Example 2 Preparation of a copolymer of acrylic acid and 10% of diallylaminomethylenephosphonic acid A mixture of 100 g of water and 20 g of isopropanol is heated to 80C, while passing through a stream of nitro-gen. A solution of 5 g of diallylaminomethylenephosphonic acid in 45 g of acrylic acid and a solution of 1.5 g of (NH4)2S2O8 in 30 g of water are synchronously added dropwise from 2 dropping funnels. After the mixture has been subsequently stirred for 4 hours, a 25% strength polymer solution ha~ing an intrinsic viscosity ~ of between 15 and 20 is obtained.

Example 3 Preparation of a copolymer of acrylic acid and 10% of diallylaminomethylenephosphonic acid 5 g of diallylaminomethylenephosphonic acid are dissolved in 120 g of water and the solution is heated to 80C, while passing in a stream of nitrogen. A catalyst solution consisting of 1.5 g of (NH4)2S20~ in 30 g of water, and a mixture of 45 g of acrylic acid and 4.5 g of thioglycolic acid, are synchronously added dropwise fr~m 2 dropping funnels at this temperatureO When the exother-mic reaction phase has ended, the mixture is subsequently :

. .

i S~

stirred at 80DC for 4 hours. Thereafter, 15 g o~ 30%
strength H2O2 are added and the mix~ure i5 stirred at 80DC
for a further hour. The colorless 25% strength polymer solution has an intrinsic viscosity X of between 15 and 20.

Example 4 Preparation of a copolymer of acrylic acid and 25~ of diallylaminomethylenephosphonic acid 12.5 g o~ diallylamino-methylenephosphonic acid are dis-solved in a mixture of 100 g of water and 20 g of isopro-panol and the solution is heaked to 75C, while passing in a stream of nitrogen. A catalyst solution consisting of 1.5 g f tNH4)2S2O8 in 30 g of water, and 37.5 g of acrylic acid are synchronously added dropwise from 2 dropping funnels at this temperature. When the exothermic reaction phase has ended, the mixture is subsequently stirred at 80C for 4 hours. The colorless 25% s~rength polymer solution has an intrinsic viscosity K of between 15 and 20.

Example 5 Preparation of a copolymer of acrylic acid and diallyl-aminomethylenephosphonic acid using H2O2 as a free radical chain initiator The procedure is as described in Example 2, but 4.5 g of 30% strength ~22 in 30 ml of water are used as the cata-lyst. A 25% strength polymer solution ha~ing an intrinsic viscosity K of between 15 and 20 is obtained.

Examples 6 and 7 Preparation of copolymers of meth~crylic acid and di-allylaminomethylenephosphonic acid The procedure is as described in Example 1, using meth-acrylic acid and 1% (Example 5) or 10% (Example 6) of diallylaminomethylenephosphonic acid.

. .

.:

.

~ J ~ ;,,i! . ? , _ 9 _ Example 8 Preparation of a terpolymer of acrylic acid, maleic acid and diallylaminomethylenephosphonic acid The procedure is as described in Example 1, using 2.5 g S of diallylaminomethylenephosphonic acid, ~4 g of acrylic acid and 24 g of maleic anhydride.

Example 9 Preparation of a terpolymer of acrylic acid, vinyl acetate and diethyl diallylaminomethylenephosphonate 30 g of acrylic acid, 30 g of vinyl acetate and 6.5 g of diethyl diallylaminomethylenephosphonate are dissolved in 174 g of toluene and the solution is heated to 80C, while passing through a stream of nitrogen. A catalyst solution of 0.2 g of AIBN in 12 g of toluene is added from a dropping funnel. When the exothermic reaction phase has ended, the mixture is allowed to after-react for 4 hours.
The polymer iB then hydrolyzed by addition of lN NaOH, the organic solvent being distilled off. A 30% strength polymer solution having an intrinsic viscosity K of between 20 and 25 is obtained.

Example 10 (Comparison Example) Preparation of a copolymer of acrylic acid and diallyl-aminomethylenephosphonic acid having a high R value A solution of 10 g of diallylaminomethylenephosphonic acid in 285 g of water is heated to 40C, while passing through a stream of nitrogen. A catalyst solution con-sisting of 3 g of (NX4)S208 in 54 g of water, and 90 g o~
acrylic acid are synchronously added dropwise from 2 dropping funnels at this temperature. After the mixture has been subsequently stirred at 50C for 5 hours, a 20~
strength polymer solution having an intrinsic viscosity K of between 130 and 140 is obtained.

The polymerization in this comparison example was carried out at relatively low temperatures, in accordance with the information in Japanese Laid-Open Specification ' . : . ' ~:

50-72,987. However, the polymers thus obtainable show no action as scale preventers.

Use Examples 1. Barium ~ulfate scale prevanter 5 The scale-preventing action was demonstrated with a tube plugging test. The principle of this test method com-prises monitoring the pressure build-up within a thermo-statically controlled capillary, through which liquid is flowing, due to the deposition of solids. ~ commercial apparatus from S.B. Systems, Aberdeen, model PMAC, was chosen.

For testing for the prevention of barium sulfate deposits, the following solutions were mixed:

1. Sulfate solu~ion 74.92 g/l of NaCl 0.93 g/l of Na2S0~
2.35 g/l of NaHC03 2. Barium solution 70.09 g/l of NaCl 1.3~ y/l of ~aCl2 1.93 g/l of CaCl2 2H20 3.81 g/l of MgCl2 ~ 6H20 Using a hose pump, the two solutions were mixed continu-ously and pumped through a stainless steel capillary of 1.1 mm internal diameter. A sensitive pressure sensor recorded the increase in pressure in the capillary, which was thermostatically controlled at 70 DC .

A slight increase to about 0.2 bar was awaited, in order to generate the precipitation of a small amount of barium sulfate on the steel surface. The inhibitor-free solution 1 was then rapidly replaced by an inhibitor-containing solution of the same composition. If the pressure remained constant, successful inhibition of BaS04 pre-, " ' '' ' , . ~ ~ ~

cipitation was concluded. If the pressure rose, the amount of inhibitor or, at the same concentration, the nature of the inhibitor was inadequate for preventing scale formation. The minimum concentration of inhibitor 5 which still ~ust prevents the deposition was thus used to evaluate the effectiveness.

The following graduations were observed by this method incomparative experiments:

Amount of inhibitor (without solvent) Product 50 ppm 40 ppm 35 ppm 30 ppm 25 ppm ~xample 1 + + + + ~ + + + + + + +
Example 2 ~ + + + + + + + + + ~ +
Example 3 + + + + + + + + + + + +
Example 8 ~ ~ + + + + + * + + + + --Example 9 + + + .......... ... ... ...
Example 10 ................ ... ... ...
Diallylamino- .................. ... Ø ...
methylenephosphonic acid, homopolymer ~Nalco V936 + + + ... ... ... ...
~Petrolite SP181 + + ~ ~ ~ + ~ ~ ~ .............. ...
~Petrolite SP245 + + + + + + + + + .............. ...

The compounds according to the invention thus already show an action against scale deposits at lower concentra-tions in comparison with the commercial products from Petrolite and Nalco which are often employed.
.

2. Calcium carbonate scale preventer Nhen testing for the prevention of calcium carbonate30 depositP, the following solutions were mixed:

Solution I NaCl 23 g~l CaC12 x 2H20 2.14 g/l MgCl2 x 6H20 0.376 g/l - :: , - 12 ~
~Cl 0.84 ~/1 Solution II NaCl 23 g/l NaHCO3 5 g/l 80C

Using a hose pump, the two solutions were pumped continu-ously through a mixing cell and ~ stainless steel capil-lary of 1.1 mm internal diameter. A sensitive pressure sensor recorded the increase in pressure in the capil-lary, which was thermostatically controlled at 80C.

An increase to about 0.8 bar was awaited in order to generate the precipitation of a thin layer of calcium carbonate on the steel surface. The scale inhibitor was then added continuously to the mixing cell via a second pump. If the pressure remained constant, successful inhibition of CaCO3 precipitation was concluded. If the pressure rose, the amount of inhibitor or, at the same concentration, the nature of the inhibitor was inadequate for preventing scale formation. The minimum concentration of inhibitor which still ~ust prevents the deposit was thus used to evaluate the effectivene s.

The following graduations were observed by this method in comparative experiments Amount of inhibitor (without solvent) Product 15 ppm 10 ppm 5 ppm 2 ppm Example 2 + + + + ~ + ... ...
Example 3 + + + + + + ... ...
Example 4 + + + + + + -~ + + ...
~Bellasol S40 + + + + + + + + + ...
Petrolite SP237 + + + + + + + + +
~Dodiscale V2870 + + + + + ~ + ~ +

The polymers according to the invention thus al80 exhibit an action against C~C03 scale~which is comparable to that ::
.

,~J ~ "i"~

of commercial brands often employed (Dodiscale V2870, Bellasol S40 and P~trolite SP237 are commercial brands of Hoechst, Ciba-Geigy and Petrolitle respectively).

3. Calcium bonding capacity and calcium dispersion The dispersion of calcium carbonate was determined by the filtration method under the following test conditions:

4 mmol of CaCl2, 4.4 mmol of Na2CO3, 2 mmol of NaOH, 250 ppm of polymer, temperature = 40C. The copol~mers according to Examples 1 and 2 disperse CaCO3 almost completely, and considerably better than the commercial product ~Sokalan CP5 (BASF) measured for comparison.
The calcium bonding capacity was mPasured by measurement of the concentration of free Ca2~ using a Ca-sensitive electrode in ~0 mmol of NH3/3Q mmol of NH~Cl buffer at a total concentration of calcium of 2 mmol and calculated by extrapolation to CpOl~r ' Product Proportion of Ca bonding capacity CaC03 dispersed [mmol of Catg of polymer]
Example 1 85 ~ 4.6 Example 2 87 ~ 4.4 ~Sokalan CP 5 23 % 5.6

Claims

1. A copolymer having a low average molecular weight corresponding to an intrinsic viscosity in the range from 10 to 100 of 0.1-50 mol %, preferably 1-15 mol %, of at least one diallylaminomethylenephosphonate of the formula Ia or Ib (CH2=CH-CH2)2N+(R1)-CHR2-PO3M-, (Ia) (CH2=CH-CH2)2N-CHR2-PO3M2 (Ib) in which R1 is hydrogen, C1- to C22-, preferably C1- to C4-alkyl, phenyl or C2- to C4-alkenyl, R2 is hydrogen, C1-to C4-alkyl or phenyl and M is hydrogen, a cation, such as Na+, K+ or NH4+, C1- to C4-alkyl or benzyl, and 99.9-50 mol %, preferably 99-85 mol %, of at least one ethylenically unsaturated carboxylic acid of the formula II

R3R4C=CR5Y (II) in which R3 is hydrogen or a group of the formula COOM, R4 is hydrogen, phenyl or a group of the formula COOM, R5 is hydrogen, methyl or a group of the formula COOM or CH2COOM, R4 and Y together are a group of the formula -C(O)-O-C(O)-or Y is a group of the formula COOM or R4 and R5 together are a C4-alkylene radical or R5 and Y together are a group of the formula -CH2-C(O)-O-C(O)-, and M is hydrogen or a cation, and 0 to 10 mol % of other ethylenically unsaturated monomers.

2. A copolymer as claimed in claim 1, which contains as other ethylenically unsaturated monomers vinylsulfonic acid, allylsulfonic acid, vinyl acetate, vinylphosphonic acid, vinylpyrrolidone, acrylamide, N-methyl-acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, or allyl compounds of the formula III

(III) in which R1, R1' and R1" independently of one another have the meanings given above for R1 or are the group CHR2-PO3M2, M is hydrogen, a cation or C1- to C4-alkyl or phenyl, R6 is hydrogen or methyl, a is 1 or 2, b is 0 or 1, a+b is 2 and X- is an anion of an organic or inorganic acid, in copolymerized form.

3. A copolymer as claimed in claim 1 or 2, which contains as monomers of the formulae Ia/Ib diallylaminomathylene-phosphonic acid, diallylaminoethylenephosphonic acid, diallylaminobenzylidenephosphonic acid or diethyl di-allylaminomethylenephosphonate in copolymerized form.

4. A copolymer as claimed in one of claims 1 to 3, which contains as monomers of the formula II acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, cinnamic acid or lower alkyl esters thereof in copolymerized form.

5. A process for the preparation of a copolymer as claimed in one of claims 1 to 4, which comprises polymer izing 0.1 to 50 mol % of the monomers of the formulae Ia/Ib, 99.9 to 50 mol % of the monomers of the formula II
and 0 to 10 mol % of the other ethylenically unsaturated monomers in water and/or in a water-miscible organic solvent, if appropriate with the addition of a regulator, in the presence of a free radical chain initiator at temperatures above 70°C.

6. A process for the preparation of a copolymer as claimed in one of claims 1 to 4, which comprises polymer-izing 0.1 to 50 mol % of the monomers of the formula Ia/Ib, 99.9 to 50 mol % of the monomers of the formula II
and 0 to 10 mol % of the other ethylenically unsaturated monomers in water and/or in a water-miscible organic solvent, with the addition of 0.001-50% by weight of a regulator, in the presence of a free radical chain initiator.

7. The use of a copolymer as claimed in claim 1 for preventing scale formation and as a builder or co-builder in detergents.