FR2714385A1 - New copolymers of phosphonic acid and carboxylic acid, - Google Patents

Abstract

New phosphonic carboxylic acid copolymers have the formula (where R = H or gp. R' = H or 1-2C alkyl; R'' = Me or Et; R''' = hydroxypropyl or hydroxyethyl; Z = OH or OM; M = metal ion; m+n+1 = an integer; l = 0-3).

Description

PHOSPHONIC ACID-CARBOXYLIC ACID COPOLYMER AND PROCESS FOR
PREPARATION OF THIS COPOLYMER
The present invention relates to a phosphonic acid-carboxylic acid copolymer and to a process for preparing it. More particularly, the present invention relates to a novel phosphonic acid-carboxylic acid copolymer, which is prepared by copolymerization and phosphorization of the acrylic acid series monomers with hypophosphorous acid (or hypophosphite) with the aid of The present invention also relates to a process for preparing said copolymer.

A phosphonic-carboxylic acid copolymer is a polymer having a group

où - Z = H ou un ion métallique - +n= 2-6; et

où - R" = H, CH3 ou QH5 - R"', R = H ou alkyle, linéaire ou ramifié, en C1-Cl8 - n = entier.It has abilities in both scale inhibition as a polycarboxylic acid does and in the inhibition of corrosion as do organic phosphorus-containing corrosion inhibitors. It has good properties for inhibiting scale precipitation of calcium carbonate, calcium phosphate and calcium sulphate, and dispersing iron hydroxide and zinc hydroxide in aqueous systems, and also has a synergy for the inhibition of corrosion. European Patent Application EP-A-0 118 970, British Patent GB-1 458 235 and US Patent
No. 4,046,707 report that the copolymer, which uses acrylic acid and a hydroxyalkyl acrylate as a monomer and hypophosphorous acid or sodium hypophosphite as a phosphor, has a high tolerance to calcium (Ca 2+ ), and has a dispersing action for silica and clay in an aqueous system. It can effectively prevent calcium, magnesium, barium, strontium, etc. scale forming, and, to some extent, exhibit corrosion inhibition capability for metal pipes. who are in contact with water. The phosphonic acid-carboxylic acid copolymer described in the above patents has the following structural formula (I or II)

where - Z = H or a metal ion - + n = 2-6; and

where - R "= H, CH3 or QH5 - R"', R = H or alkyl, linear or branched, C1-C18 - n = integer.

 The copolymerization and phosphoration of the phosphonecarboxylic copolymer mentioned above is carried out using acrylic acid, a hydroxyalkyl acrylate as a monomer, as well as hypophosphorous acid or hypophosphite as phosphor.

 The disadvantages of the above preparation methods are a lack of homogeneity in the polymerization and a difficulty in conducting the operation because some of the monomer and hypophosphite are added to the reactor together.

 The disadvantages of the phosphonic acid-carboxylic acid copolymer having the formula (I) or (II) are that the activity of preventing and dispersing scale is not very good, especially at high temperature, and that the synergy of the inhibition of corrosion is not good either.

 In order to overcome the disadvantages of the phosphonic-carboxylic acid copolymer of formula (I) or (II), one of the objectives of the invention is to provide a novel phosphonic carboxylic acid copolymer structure which has a high activity in the prevention and the dispersion of the scale, in particular at a high temperature, its synergy of inhibition of the corrosion being also good.

 To overcome the defects of the process for the preparation of the phosphonic-carboxylic acid copolymer of the prior art, another object of the invention is to provide a novel process for the preparation of a phosphonic-carboxylic acid copolymer, which shows homogeneity during the polymerization and is easy to implement.

dans laquelle

- R' = H ou alkyle en C1-C2 ; - R" = méthyle ou éthyle - R"' = hydroxypropyle ou hydroxyéthyle - Z = OH ou OM, M représentant un ion métallique,
notamment un ion de métal alcalin - m + n + 1 = entier - 1 = O ou 1 - 3.The present invention relates to a novel phosphonic acid-carboxylic acid copolymer represented by the following formula (III)

in which

- R '= H or C1-C2 alkyl; - R "= methyl or ethyl - R"'= hydroxypropyl or hydroxyethyl - Z = OH or OM, M representing a metal ion,
in particular an alkali metal ion - m + n + 1 = integer - 1 = O or 1 - 3.

 The process for the preparation of the novel phosphonic-carboxylic acid copolymer according to the invention comprises the following steps: copolymerization of the monomers chosen from acrylic acid, methacrylic acid or a hydroxyalkyl methacrylate, phosphoring with a hypophosphite as phosphor a peroxide being used as initiator.

- R' = H ou alkyle - R" = méthyle ou éthyle - R"' = hydroxypropyle ou hydroxyéthyle - Z = OH ou OM, M représentant un ion métallique,
notamment un ion de métal alcalin - m + n + 1 = entier - 1 = 0 ou 1 - 3.The novel phosphonic carboxylic acid copolymer of the present invention has the following formula (III)

- R '= H or alkyl - R "= methyl or ethyl - R"' = hydroxypropyl or hydroxyethyl - Z = OH or OM, M representing a metal ion,
in particular an alkali metal ion - m + n + 1 = integer - 1 = 0 or 1 - 3.

 The phosphonic-carboxylic acid copolymers according to the present invention are phosphonic-carboxylic acid copolymers having one or two groups selected from alkyl groups (for example, methyl, ethyl, etc.) and phenyl sulfonic acid, and the like. Due to the introduction of the groups identified above, the thermo-tolerance of the phosphonic-carboxylic acid copolymer is considerably improved.

The invention also relates to a process for the preparation of said phosphonic carboxylic acid copolymer, which process comprises the following steps: - dissolving a phosphorus agent in water with
a concentration of 5 - 10% (by weight) - heating at a temperature between 50 ° C and the
reflux temperature; and - dropwise addition of the monomers of the series of
acrylic acid and 11 peroxide initiator
simultaneously, while stirring, while maintaining
temperature to a value between 50 "C and the
reflux temperature - maintaining the mixture at a temperature between
500C and the reflux temperature, for a period of
time of 10 to 180 minutes, after all the reagents
have been added, and cooling to get the
product.

 In accordance with the process of the present invention, the monomer solution and the initiator solution can be added dropwise to the solution of the phosphor, to copolymerize and phosphorize the reaction mixture.

 The phosphorating agent, which is selected from hypophosphorous acid, hypophosphite, phosphorus trichloride, phosphorous acid, etc., is dissolved in water at a concentration of 5-10% (by weight) . The solution is heated to a temperature of between 50 ° C. and the reflux temperature before adding dropwise the monomers and the initiator.

 The monomer (hereinafter referred to as monomer 1), which is selected from acrylic acid and methacrylic acid, and the monomer (hereinafter referred to as monomer 2), which consists of one or two monomers hydroxypropyl methacrylate, hydroxyethyl methacrylate and sodium p-vinylphenylsulfonate are used in a proportion of 50:50 to 95: 5, the total weight of the monomers and the weight of the the phosphor agent being in a proportion of 100: 30 to 100: 3 (by weight). The monomers and the initiator are added dropwise simultaneously to the phosphorization agent solution, with stirring, when the phosphor is heated to a temperature of between 500 ° C. and the reflux temperature, and this temperature is maintained at this temperature. .

 The initiator, which is selected from a persulfate, such as ammonium persulfate, potassium persulfate, hydrogen peroxide or a mixture thereof, is used in an amount of 2 - 25% ( by weight) of the total weight of the monomers.

 The reaction mixture is maintained at a temperature of between 50 ° C and the reflux temperature for a period of 10-180 minutes, after the monomers and initiator have been added dropwise, so that that the mixture can be completely polymerized and phosphorized, then the reaction mixture is cooled, and the phosphonic carboxylic acid copolymer according to the present invention is obtained.

 The phosphonic acid-carboxylic acid copolymer according to the present invention has good properties for inhibiting the scale and calcium carbonate dispersion, calcium phosphate, calcium sulphate, iron hydroxide, zinc hydroxide and earth. In particular, it has a good tolerance to calcium. Its thermo-tolerance has been considerably improved because of the special molecular structure according to the present invention. Thus, it can be used in water treatment processes at a high temperature. The polymer of the present invention can also be used in all the various production departments to process cooling water, boiler water, oilfield brine, and be used in desalination of seawater.

 The process for the preparation of the phosphonic acid-carboxylic acid copolymer according to the present invention, which comprises adding the monomer solution and the initiator solution simultaneously and uniformly, so that the polymerization and phosphoration take place in a homogeneous and controllable way, can be implemented, and will be safe and stable for its application in the industry.

 The following examples illustrate the present invention, but should not be construed as limiting the scope.

Example 1
In a reactor equipped with a condenser and stirrer, an aqueous solution of phosphor (7.3 g of sodium hypophosphite in 92.7 g of water) was placed. The solution was refluxed with stirring, followed by the monomer solution (67.2 g of acrylic acid and 33.6 g of hydroxypropyl methacrylate in 137.2 g of water) and the initiator solution ( 10.9 g of ammonium persulfate in 47.5 g of water) were added dropwise simultaneously while the temperature was maintained at 100 to 1200 ° C and the mixture was maintained at this temperature for a period of time. hour, then cooled. An orange red transparent liquid having a relative viscosity of 1.0455 and a solids content of 30% was obtained.

Example 2
The same procedure as that described in Example 1 was carried out except that the monomer solution was changed to 80 g of acrylic acid, 16 g of hydroxypropyl methacrylate and 122.7 g of water, and the initiator solution was changed to 12.5 g of ammonium persulfate and 47.6 g of water. A product having a relative viscosity of 1.0399 and a solids content of 30% was obtained.

EXAMPLE 3
The same procedure as that described in Example 1 was carried out except that the amount of sodium hypophosphite was changed to 6.1 g in 92.9 g of water, as the amount of the monomer solution was changed to 82.2 g of methacrylic acid and 16.4 g of hydroxypropyl methacrylate in 112 g of water, and that the initiator solution was changed to 10.4 g of ammonium persulfate in 49.6 g of water, and after the dropwise addition, the solution was heated at 100-100 ° C. for two hours. A product having a relative viscosity of 1.0521 and a solids content of 30% will be obtained.

Example 4
The same procedure as described in Example 1 was conducted except that the amount of sodium hypophosphite was changed to 8.3 g in 82.7 g of water, that the monomer solution was changed. in 91.6 g of acrylic acid and 9.2 g of hydroxyethyl methacrylate in 136.2 g of water, and that the initiator solution was changed to 10.9 g of ammonium persulfate in 49 , 1 g of water, and after the dropwise addition, the solution was heated at 100-100 ° C. for 1.5 hours. A product having a relative viscosity of 1.0370 and a solids content of 30% was obtained.

Example 5
The same procedure as described in Example 1 was conducted except that the amount of sodium hypophosphite in the phosphorizing agent solution was changed to 13 g, the monomer solution was changed to 80. g of acrylic acid and 16 g of hydroxypropyl methacrylate in 132.6 g of water, that the initiator solution was changed to 11.0 g of sodium persulfate in 49 g of water, and that After adding dropwise, the solution was heated at 100-100 ° C. for 2.5 hours. A product having a relative viscosity of 1.0455 and a solids content of 30% was obtained.

Example 6
The same procedure as that described in Example 1 was carried out except that the phosphorizing agent solution was changed to 23.1 g of sodium hypophosphite in 76.7 g of water, that the solution of The monomers were changed to 48 g of acrylic acid and 48 g of hydroxypropyl methacrylate in 172.4 g of water, and the initiator solution was changed to 13.8 g of potassium persulfate in 46 g. of water. A product having a relative viscosity of 1.0355 and a solids content of 29% was obtained.

Example 7
The same procedure as that described in Example 1 was carried out except that the solution of the phosphor was changed to 23.1 g of sodium hypophosphite in 76.7 g of water, which the The monomer solution was changed to 48 g of acrylic acid and 24 g of hydroxypropyl methacrylate and 24 g of sodium p-vinylphenylsulphonate in 167.2 g of water, and the initiator solution was changed. in 7.1 g of ammonium persulfate and 6.7 g of hydrogen peroxide in 46 g of water. A product having a relative viscosity of 1.0355 and a solids content of 30% was obtained.

Experience
A thermotolerance experiment was conducted under the following conditions
The sample solution was boiled and concentrated to one-third of the original volume, and then water was added until the initial volume was restored. The operation was repeated 12 times;
The amount of copolymer added before heating is 4 ppm.

 The amount of copolymer added after heating is 10 ppm.

Experimental conditions for calcium carbonate scale prevention rate: Ca2 + (calculated as CaCO3) 600 ppm, pH 9, 80 C, 6 hours;
Experimental conditions for Calcium Phosphate Tumor Prevention Rate: Ca 2+ (calculated as CaCO 3) 250 ppm, For 6 ppm, pH 9, 80 ° C, 6 hours.

 The experimental results were presented in Table 1.

Table 1

<tb><SEP> Inhibition Rate <SEP><SEP> SEP Inhibition Rate <SEP>
<tb><SEP> of the <SEP> Tumor <SEP> of <SEP> CaCO3 <SEP> Tumor <SEP> of <SEP> Ca3 <SEP>(<SEP> Po4 <SEP>) <SEP> 2 <SEP>
<tb><SEP> (%) <SEP> (%)
<tb> Polymers <SEP> before <SEP> after <SEP> before <SEP> after
<tb><SEP> heating <SEP> heating <SEP> heating <SEP> heating
<tb><SEP> ge
<tb> Homopolymer
<tb> e <SEP> acid <SEP> 100 <SEP> 92.0 <SEP> 77.0 <SEP> 56.0
<tb> phosphoniqu
<tb> e
<tb> carboxyl <SEP> iqu <SEP>
<tb> e * <SEP>
<tb> Copolymer
<tb> Acid <SEP> 100 <SEP> 97.0 <SEP> 94.0 <SEP> 93.0
<tb> phosphoniqu
<tb> e
<tb> carboxylic
<tb> e ** <SEP>
<tb> Product <SEP> of <SEP> 100 <SEP> 98.0 <SEP> 93.0 <SEP> 98.0
<tb> Example <SEP> 2
<tb> Product <SEP> of <SEP> - <SEP><SEP> 99.0 <SEP> - <SEP><SEP> 99.01
<tb> Example <SEP> 7
<Tb>
Note * Homopolymer of acrylic acid containing phosphorus,
commercially available ** Acrylic acid copolymer containing phosphorus /
hydroxypropyl methacrylate, available in the
trade.

Claims (8)

 1-Phosphonic-carboxylic acid copolymer, prepared by copolymerization and phosphorization of the monomers of the series of acrylic acid with hypophosphorous acid or hypophosphite, using a peroxide as initiator, via a copolymerization by free radicals, said copolymer having the following formula

 - R '= H or C1-C2 alkyl; - R "= methyl or ethyl - R" '= hydroxypropyl or hydroxyethyl - Z = OH or OM, M representing a metal ion; - m + n + 1 = integer - 1 = O or 1 - 3.  2 - phosphonic-carboxylic acid copolymer according to claim 1, characterized in that M is an alkali metal ion.  3 - Process for the preparation of a phosphonic acid-carboxylic acid copolymer, as defined in claim 1 or 2, characterized in that it comprises the operations of - dissolving a phosphorus agent in water with a  concentration of 5 - 10% by weight - heat to a temperature between 500C and the  reflux temperature; - add drop by drop the monomer from the series of  acrylic acid and the peroxide initiator, under  stirring, while maintaining the temperature above  then - heat the mixture to a temperature of 50 to 1200C and  maintain for a period of time from 10 - 180 minutes,  cool down and get the product.  4 - Process according to claim 3, characterized in that the monomers of the series of acrylic acid comprise a monomer 1, which is acrylic acid or methacrylic acid, and a monomer 2, which consists of one or two monomers selected from the group consisting of hydroxypropyl methacrylate, hydroxyethyl methacrylate and sodium p-vinylphenylsulfonate.  5 - Process according to claim 4, characterized in that the proportion of monomer 1 and monomer 2 is 50:50 to 95: 5 (by weight).  6 - Process according to claim 3, characterized in that the peroxide initiator is selected from the group consisting of ammonium persulfate, potassium persulfate, hydrogen peroxide and mixtures thereof, and that its weight represents 2-25% of the total weight of the monomers.  7 - Process according to claim 3, characterized in that the phosphor is selected from the group consisting of hypophosphorous acid, sodium hypophosphite, phosphorus trichloride and phosphorous acid.  8 - Process according to claim 7, characterized in that the phosphor is hypophosphorous acid or sodium hypophosphite.