CA1292866C - Aminomethylenephosphonate compositions - Google Patents
Aminomethylenephosphonate compositionsInfo
- Publication number
- CA1292866C CA1292866C CA000524138A CA524138A CA1292866C CA 1292866 C CA1292866 C CA 1292866C CA 000524138 A CA000524138 A CA 000524138A CA 524138 A CA524138 A CA 524138A CA 1292866 C CA1292866 C CA 1292866C
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- CA
- Canada
- Prior art keywords
- weight
- diethylenetriaminepenta
- sodium sulphate
- dtpma
- composition
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
AMINOMETHYLENEPHOSPHONATE COMPOSITIONS
Abstract Granular or powder compositions containing diethylenetriamine-penta(methylenephosphonic acid) and/or its salts in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of at least 60% of the dry weight of the diethylenetriaminepenta(methylene-phosphonic acid) and/or its salts can be stored for extended periods while remaining in the form of free-flowing solids.
Abstract Granular or powder compositions containing diethylenetriamine-penta(methylenephosphonic acid) and/or its salts in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of at least 60% of the dry weight of the diethylenetriaminepenta(methylene-phosphonic acid) and/or its salts can be stored for extended periods while remaining in the form of free-flowing solids.
Description
lZ9Zt3~i6 AMINOMETHYLENEPHOSPHONATE COMPOSITIONS
This invention relates to aminomethylenephosphonate compositions, more especially to compositions which are solids containing diethylenetriaminepenta(methylenephosphonic acid) (DTPMA) and/or its salts.
DTPMA and its salts have a variety of uses, for example as sequestrants, anti-incrustation agents, and stabilisers for hydrogen peroxide. The products are currently available as aqueous solutions containing approximately 50% by weight total diethylenetriaminepoly(methylenephosphonic acids) (DTpMAs) of which typically approximately 70~0, but more widely from about 50%
to about 80% by weight is DTPMA and most of the remainder is diethylenetriaminetri(methylenephosphonic acid).
For certain applications, it would be desirable to be able to handle DTPMA and/or its salts in the form of solids. However, recovery of solids by crystallisation from the solutions is inefficient, and the solids which are obtained as residues by evaporation of aqueous solutions are hygroscopic and in some instances deliquescent.
We have now found that certain granular or powder compositions conta~ning DTPMA and/or its salts in admixture with sodium sulphate or sodium bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of at least 60% of the dry weight of the DTPMA andtor DTPMA salt, can be stored for considerable periods while remaining in the form of free-flowing solids.
In determining the figure of 60%, other DTpMA components in a mixture of DTpMAs and/or DTpMA salts are not taken into consideration.
lZ9'~:~66 In accordance with an embodiment of the present invention there is provided a composition in mobile granular or powder form consisting essentially of diethylenetriaminepenta(methylenephosphonic acid) and/or a salt of diethylenetriaminepenta(methylene-phosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylenetriaminepenta(methylenephosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
In accordance with another embodiment of the present invention there is provided a compositlon in mobile granular or powder form consisting of diethylenetriaminepenta(methylenephosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the e~uivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylenetriaminepenta(methylene-phosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
In general, compositions which contain DTPMA as such, i.e. in the acid form, rather than in the form of DTPMA salts, have better storage stability, i.e.
remain as free-flowing solids for longer.
Alternatively expressed, in compositions containing DTPMA and DTPMA salts, the storage stability decreases as the proportion of DTPMA salts increases, at a given level of sodium sulphate/bisulphate. Storage stability at a given ratio of DTPMA/DTPMA salt increases as the amount of sodium sulphate/bisulphate 1~92866 - 2a -increases. Although there is no necessary upper limit to the ratio of sulphate/bisulphate to DTPMA/DTPMA
salt in the composition of the invention, in practice it will be usual to use not significantly more sodium sulphate/bisulphate than is required to achieve the desired degree of storage stability. Typically, the compositions of the invention contain sodium sulphate or sodium bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200~, for example from 60% to 150% of the dry weight of the DTPMA and/or DTPMA salt.
The commercially most significant salt is the sodium salt, but the invention is also applicable to other DTPMA salts, for example other alkali metal salts, ammonium salts and alkaline earth metal salts.
The compositions of the invention can be produced in various ways. For example, solutions containing the components of such compositions can be formed by adding sodium sulphate or bisulphate to a solution, or a neutralised or partially neutralized solution, of DTPMA. Alternatively the sodium sulphate and/or sodium bisulphata can be formed in situ by the addition of sodium hydroxide to a solution of Dl'PMA
and sulphuric acid. Use of increaslny amounts of sodium hydroxide in this procedura results in the formation of sodium sulphate rather than sodium bisulphate, and progressive deprotonisation of the phosphonic acid groups of ~Z9Z866 the DTPMA. The compositions of the invention are obtained by evaporation of such solutions to dryness or to low moisture content, for example a ,aximum of 10% of the weight of the composition, most conveniently by spray drying.
As indicated above, in compositions containing DTPMA and DTPMA salts, the storage stability decreases as the proportion of DTPMA salts increases, at a given level of sodium sulphate/
bisulphate. This effect can be quantified in terms of the acidity of the solutions from which the compositions of the invention can be obtained by evaporation as described above.
Thus, preferred compositions are obtained by the evaporation of solutions which, at a 10% by weight concentration of the components, have a pH less than 7, for example from 1.0 to 6.5.
Other components may be present in the compositions of the invention provided they do not adversely affect the storage stability of the product to a significant extent. Examples include certain other al li metal sdl~i such as sodium chloride (which may be present because some comlllercial solutions of DTPMA
contain hydrochloric acid). Preferably, however, the amount of sodium chloride does not exceed 10% of the total weight of the composition. Other examples include other non-hygroscopic inert organic or inorganic materials, for instance aluminosllicates or surface active agents.
The invention is illustrated by the following Examples.
Example 1 (Control) A solution containing 20% by weight of diethylenetriaminepoly-(methylenephosphonic acid)s (DTpMAs) was prepared. Approximately 70% of the total poly(methylenephosphonic acid)s was the penta-(methylenephosphonic acid) and most of the remainder was the tri(methylenephosphonic acid).
The solution was divided into portions, and each portion was diluted to approximately 10% concentration. The pH values of the solutions thus obtained were adjusted to different levels, as shown in the table below, by the addition of sodium hydroxide solution. Each solution was then spray dried to a powder having a particle s~ze of 10-40 um using a laboratory spray dryer.
15 Characteristics of the powders obtained are given in the following table.
~ by weight Product after 24 hours mo;sture in storage at 25~C, 80% RH
lnitial product % by weightAppearance 20 pH of solution after spray drying moisture.
Z 12.3 13.2 Caked 4 11.1 15.8 Paste 6 12.4 27.3 Paste 8 14.3 36.5 Paste Example 2 A solution of DTpMAs was prepared as in Example 1. Sulphuric acid was then added so that the total in the solution was an amount equivalent to 74% of Na2S04 relative to the dry weight of DTpMAs, i.e. about 106% of Na2S04 relative to the dry weight of DTPMA.
Portions of diluted (10%) solution were adjusted to different pH
levels and then spray dried. Results are shown below.
% by weight Product after 24 hours moisture in storage at 25C, 80% RH
initial product % by weight Appearance pH of solution after spray drying moisture.
This invention relates to aminomethylenephosphonate compositions, more especially to compositions which are solids containing diethylenetriaminepenta(methylenephosphonic acid) (DTPMA) and/or its salts.
DTPMA and its salts have a variety of uses, for example as sequestrants, anti-incrustation agents, and stabilisers for hydrogen peroxide. The products are currently available as aqueous solutions containing approximately 50% by weight total diethylenetriaminepoly(methylenephosphonic acids) (DTpMAs) of which typically approximately 70~0, but more widely from about 50%
to about 80% by weight is DTPMA and most of the remainder is diethylenetriaminetri(methylenephosphonic acid).
For certain applications, it would be desirable to be able to handle DTPMA and/or its salts in the form of solids. However, recovery of solids by crystallisation from the solutions is inefficient, and the solids which are obtained as residues by evaporation of aqueous solutions are hygroscopic and in some instances deliquescent.
We have now found that certain granular or powder compositions conta~ning DTPMA and/or its salts in admixture with sodium sulphate or sodium bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of at least 60% of the dry weight of the DTPMA andtor DTPMA salt, can be stored for considerable periods while remaining in the form of free-flowing solids.
In determining the figure of 60%, other DTpMA components in a mixture of DTpMAs and/or DTpMA salts are not taken into consideration.
lZ9'~:~66 In accordance with an embodiment of the present invention there is provided a composition in mobile granular or powder form consisting essentially of diethylenetriaminepenta(methylenephosphonic acid) and/or a salt of diethylenetriaminepenta(methylene-phosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylenetriaminepenta(methylenephosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
In accordance with another embodiment of the present invention there is provided a compositlon in mobile granular or powder form consisting of diethylenetriaminepenta(methylenephosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the e~uivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylenetriaminepenta(methylene-phosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
In general, compositions which contain DTPMA as such, i.e. in the acid form, rather than in the form of DTPMA salts, have better storage stability, i.e.
remain as free-flowing solids for longer.
Alternatively expressed, in compositions containing DTPMA and DTPMA salts, the storage stability decreases as the proportion of DTPMA salts increases, at a given level of sodium sulphate/bisulphate. Storage stability at a given ratio of DTPMA/DTPMA salt increases as the amount of sodium sulphate/bisulphate 1~92866 - 2a -increases. Although there is no necessary upper limit to the ratio of sulphate/bisulphate to DTPMA/DTPMA
salt in the composition of the invention, in practice it will be usual to use not significantly more sodium sulphate/bisulphate than is required to achieve the desired degree of storage stability. Typically, the compositions of the invention contain sodium sulphate or sodium bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200~, for example from 60% to 150% of the dry weight of the DTPMA and/or DTPMA salt.
The commercially most significant salt is the sodium salt, but the invention is also applicable to other DTPMA salts, for example other alkali metal salts, ammonium salts and alkaline earth metal salts.
The compositions of the invention can be produced in various ways. For example, solutions containing the components of such compositions can be formed by adding sodium sulphate or bisulphate to a solution, or a neutralised or partially neutralized solution, of DTPMA. Alternatively the sodium sulphate and/or sodium bisulphata can be formed in situ by the addition of sodium hydroxide to a solution of Dl'PMA
and sulphuric acid. Use of increaslny amounts of sodium hydroxide in this procedura results in the formation of sodium sulphate rather than sodium bisulphate, and progressive deprotonisation of the phosphonic acid groups of ~Z9Z866 the DTPMA. The compositions of the invention are obtained by evaporation of such solutions to dryness or to low moisture content, for example a ,aximum of 10% of the weight of the composition, most conveniently by spray drying.
As indicated above, in compositions containing DTPMA and DTPMA salts, the storage stability decreases as the proportion of DTPMA salts increases, at a given level of sodium sulphate/
bisulphate. This effect can be quantified in terms of the acidity of the solutions from which the compositions of the invention can be obtained by evaporation as described above.
Thus, preferred compositions are obtained by the evaporation of solutions which, at a 10% by weight concentration of the components, have a pH less than 7, for example from 1.0 to 6.5.
Other components may be present in the compositions of the invention provided they do not adversely affect the storage stability of the product to a significant extent. Examples include certain other al li metal sdl~i such as sodium chloride (which may be present because some comlllercial solutions of DTPMA
contain hydrochloric acid). Preferably, however, the amount of sodium chloride does not exceed 10% of the total weight of the composition. Other examples include other non-hygroscopic inert organic or inorganic materials, for instance aluminosllicates or surface active agents.
The invention is illustrated by the following Examples.
Example 1 (Control) A solution containing 20% by weight of diethylenetriaminepoly-(methylenephosphonic acid)s (DTpMAs) was prepared. Approximately 70% of the total poly(methylenephosphonic acid)s was the penta-(methylenephosphonic acid) and most of the remainder was the tri(methylenephosphonic acid).
The solution was divided into portions, and each portion was diluted to approximately 10% concentration. The pH values of the solutions thus obtained were adjusted to different levels, as shown in the table below, by the addition of sodium hydroxide solution. Each solution was then spray dried to a powder having a particle s~ze of 10-40 um using a laboratory spray dryer.
15 Characteristics of the powders obtained are given in the following table.
~ by weight Product after 24 hours mo;sture in storage at 25~C, 80% RH
lnitial product % by weightAppearance 20 pH of solution after spray drying moisture.
Z 12.3 13.2 Caked 4 11.1 15.8 Paste 6 12.4 27.3 Paste 8 14.3 36.5 Paste Example 2 A solution of DTpMAs was prepared as in Example 1. Sulphuric acid was then added so that the total in the solution was an amount equivalent to 74% of Na2S04 relative to the dry weight of DTpMAs, i.e. about 106% of Na2S04 relative to the dry weight of DTPMA.
Portions of diluted (10%) solution were adjusted to different pH
levels and then spray dried. Results are shown below.
% by weight Product after 24 hours moisture in storage at 25C, 80% RH
initial product % by weight Appearance pH of solution after spray drying moisture.
2 7.1 7.9 Mobile powder 4 7.2 12.0 Mobile powder 6 6.7 22.6 Mobile powder 8 9.6 33.1 Caked 8.6 32.9 Caked ~e~
Example 2 WdS repeated except that the amount of sulphuric acid added gave a total equivalent to 111% of Na2S04 relative to the dry weight of DTpMAs, i.e. about 159% of Na2S04 relative to the dry weight of DTPMA. Results are shown below.
`` 129Z866 % by weight Product after 24 hours moisture in storage at 25C, 80~ RH
initial product % by weight Appearance 5 pH of solutionafter spray drying moisture.
Example 2 WdS repeated except that the amount of sulphuric acid added gave a total equivalent to 111% of Na2S04 relative to the dry weight of DTpMAs, i.e. about 159% of Na2S04 relative to the dry weight of DTPMA. Results are shown below.
`` 129Z866 % by weight Product after 24 hours moisture in storage at 25C, 80~ RH
initial product % by weight Appearance 5 pH of solutionafter spray drying moisture.
3.1 6.4 8.2 Mobile powder 4.1 8.5 11.3 Mobile powder 5.1 10.2 15.3 Mobile powder 6.1 4.45 16.0 Mobile powder Comparison of the results of Examples 2 and 3 with those of control Example 1 shows the advantages of the compositions of the invention relative to spray dried DTPMAs alone.
Claims (9)
1. A composition in mobile granular or powder form consisting essentially of diethylenetriaminepenta(methylenephosphonic acid) and/or a salt of diethylenetriaminepenta-(methylenephosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylenetriaminepenta(methylenephosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
2. A composition according to claim 1 in which the salt of diethylenetriaminepenta(methylene-phosphonic acid) is the sodium salt.
3. A composition according to claim 1 which contains a mixture of diethylenetriaminepoly-(methylenephosphonic acids) and/or salts, of which from 50% to 80% by weight is diethylenetriaminepenta-(methylenephosphonic acid) and/or its salts.
4. A composition according to claim 1 which has been obtained by evaporation of an aqueous solution containing components which on evaporation will provide such a composition, the acidity of the solution being such that a 10% by weight concentration of the components has a pH less than 7.
5. A composition according to claim 4 obtained from a solution which at a 10% by weight concentration of the components has a pH of from 1.0 to 6.5.
6. A composition according to either of claims 4 or 5 having a moisture content of 10% by weight or less at the completion of the evaporation.
7. A composition according to claim 1 wherein the pH of the aqueous solution is in the range of from about 1 to about 6.5.
8. A composition according to claim 7 in which the pH is 6.1.
9. A composition in mobile granular or powder form consisting of diethylenetriaminepenta(methylene-phosphonic acid) in admixture with sodium sulphate and/or bisulphate in an amount, expressed as the equivalent amount of anhydrous sodium sulphate, of from 60% to 200% of the dry weight of the diethylene-triaminepenta(methylenephosphonic acid) and/or its salt, the composition when in aqueous solution at a concentration of 10% by weight exhibiting a pH of less than 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000524138A CA1292866C (en) | 1986-11-28 | 1986-11-28 | Aminomethylenephosphonate compositions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000524138A CA1292866C (en) | 1986-11-28 | 1986-11-28 | Aminomethylenephosphonate compositions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292866C true CA1292866C (en) | 1991-12-10 |
Family
ID=4134459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000524138A Expired - Lifetime CA1292866C (en) | 1986-11-28 | 1986-11-28 | Aminomethylenephosphonate compositions |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1292866C (en) |
-
1986
- 1986-11-28 CA CA000524138A patent/CA1292866C/en not_active Expired - Lifetime
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| Date | Code | Title | Description |
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| MKEX | Expiry | ||
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Effective date: 20081210 |