JPS63114986A - Anionic surfactant containing maleic acid polymer - Google Patents

Abstract

PURPOSE:To provide superior performance as a scaling or corrosion inhibitor by polymerizing maleic acid (salt) with a polymn. initiator in the presence of a hypophosphite to obtain an anionic surfactant contg. a maleic acid polymer having P-C bonds in the molecule. CONSTITUTION:An alkali metallic hydroxide such as NaOH is added to an aq. soln. of maleic acid or a mixture of maleic acid with a water soluble monomer copolymerizable with maleic acid to prepare an aq. maleate soln. of 2.5-6.0pH. After hypophosphorous acid is added to the soln., the soln. is heated, a polymn, initiator is added and polymn. is carried out to obtain an anionic surfactant contg. a maleic acid copolymer having P-C bonds in the molecule. The polymer has a significant scaling or corrosion inhibiting effect and is useful as a water treating agent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an anionic surfactant containing a maleic acid polymer having a P-C bond in the molecule,
Specifically, maleic acid or a salt thereof alone or a mixture thereof with a copolymerizable water-soluble supernatant is polymerized in the presence of a hypophosphite in an aqueous solution while maintaining the pH at 2.5 to 6.0. The present invention relates to an anionic surfactant containing a maleic acid polymer having a PC bond in the molecule obtained by polymerization using an initiator.

[Conventional technology]

Maleic acid homopolymers or copolymers, various phosphoric acid compounds, and sodium acrylate homopolymers and copolymers are used as water treatment agents, dispersants, cleaning agents, and the like. It is also known to use a reaction product of acrylic acid and sodium hypophosphite as a water treatment agent (Japanese Unexamined Patent Application Publication No. 55-111)
(See Publication No. 11092).

[Problem that the invention seeks to solve]

When phosphoric acid compounds are used as water treatment agents, if they are discharged outside the system, they cause eutrophication and cause environmental pollution.

Furthermore, since it undergoes hydrolysis in water, there is a problem in its scale suppression effect in systems with long residence times or high temperatures.

When maleic acid homopolymer or copolymer is used as a water treatment agent, it has an excellent scale inhibiting effect, but its effect as a corrosion inhibitor is not sufficient. It is expensive because it uses an expensive polymerization initiator.

The reaction product of acrylic acid and sodium hypophosphite is a water treatment agent,
In particular, the effect as a scale inhibitor is not sufficient.

[Means for solving problems]

As a result of intensive research to solve these conventional problems, the present inventors found that maleic acid polymers having p-C bonds in the molecule are excellent as anionic surfactants, especially as scale inhibitors and corrosion inhibitors. The present inventors have discovered that the present invention has excellent performance, and have completed the present invention.

That is, the present invention maintains maleic acid or a salt thereof alone or a mixture thereof with a water-soluble monomer copolymerizable with the maleic acid in an aqueous solution at a pH of 2.5 to 6.0 in the presence of a hypophosphite. p in the molecule obtained by polymerization with a polymerization initiator.
An anionic surfactant containing a maleic acid polymer having a -C bond is provided.

Maleic acid or its salt and hypophosphite are added to a polymerization initiator in an aqueous solution whose pH is maintained at 2.5 to 6.0 with an alkali metal compound, an alkaline earth metal, or a basic compound such as ammonia. By polymerizing at 50°C to 150°C in the presence of , it can be produced with higher yield.

Specifically describing the production method of the present invention, first, an aqueous solution of maleic acid or maleic anhydride is prepared, and an alkali metal hydroxide (for example, sodium hydroxide, etc.) is added thereto at a concentration of 90 to 110 mol per 100 mol of maleic acid. By adding moles, an aqueous maleate solution is obtained. The pH at this time is 2.5
or 6.0. After adding hypophosphite to the aqueous solution, the temperature is 50°C to 150°C, preferably 80°C to 110°C.
Polymerization is carried out by heating or dropping a polymerization initiator in an amount of 0.1 to 100 moles, preferably 0.5 to 30 moles, per 100 moles of maleic acid. pH
If the reaction rate is outside the above range, the reaction rate and degree of polymerization will be low, and a large amount of unreacted hypophosphorous acid etc. will be present.

By such a method, the polymer according to the present invention can be efficiently and easily produced. The reason for this is not clear, but in the pH range of the present invention, most maleic acid exists as a maleic acid monosalt, and this maleic acid monosalt forms intramolecular hydrogen bonds in an aqueous solution and takes a planar structure. , it is thought that radical resonance stabilization increases and its polymerizability increases.

Water is used as the solvent, but aqueous ethanol or the like may be used instead of water. The molar ratio of maleic acid salt) and hypophosphite is 100:10~
100: 100 is preferable, more preferably 100
: 20-100 : 50.

Examples of the polymerization initiator include hydroperoxides such as t-butyl hydroperoxide, persulfates such as sodium persulfate, hydrogen peroxide, and water-soluble azobis compounds. Hydrogen oxide is particularly suitable.

The molecular weight of the polymer or salt thereof according to the present invention is 200 to 5.
000 is preferred. In addition, the molecular weight referred to here is a value measured by the following method. That is, the resulting polymer is made into an acid form using an ion exchange resin, then methyl esterified with diazomethane or the like, and measured by vapor osmotic pressure method in a solvent such as chloroform.

The polymer of the present invention includes polyacrylic acid, polymaleic acid,
Alternatively, it exhibits superior scale-inhibiting effects or corrosion-inhibiting effects, as shown in Examples, as compared to polymers obtained by reacting acrylic acid and sodium hypophosphite. The reason for this is not clear, but because it has a maleic acid skeleton, the number of charges in the molecule is large, so it has high dispersion power, and because it has a phosphorus bond in the molecule, it has excellent adsorption properties. Therefore, it is thought that it will have an effect that has not been seen before. At least one hypophosphite in this polymer is bound in the molecule, and the hypophosphorous acid seems to be bound not only to the ends of the molecule but also to the center. The presence of a P-C bond in the molecule was confirmed by P-NMR.

In addition, in the polymer of the present invention, a water-soluble vinyl monomer copolymerizable with maleic acid may be used in combination. Examples of such copolymerizable water-soluble vinyl monomers include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, unsaturated amides such as acrylamide, and unsaturated (meth) acrylates such as methyl acrylate and ethyl acrylate. Examples include unsaturated allyl ethers such as acrylic acid esters, allyl alcohol, and allyl alcohol EO adducts, and unsaturated sulfonic acids such as styrene sulfonic acid and vinyl sulfonic acid, but acrylic acid, methacrylic acid, and itaconic acid are preferably used. be done.

These copolymerizable monomers are used in an amount equal to or less than the molar amount of maleic acid. In addition, when such copolymerized monomers are used,
In calculating the ratio of maleic acid (salt) and hypophosphite described above, the copolymerization monomer is included in maleic acid (salt).

In the polymer according to the present invention, part or all of the acidic hydrogen atoms may be replaced by a monovalent metal, a divalent metal, or an ammonium ion.

The surfactant of the present invention has a solid content of 40 to 6 by polymerization reaction.
It is obtained as a 0% aqueous solution. In this form,
It may be used as a water treatment agent, dispersant, or chelating agent, or it may be purified and used.

When the surfactant of the present invention is used as a water treatment agent, the amount added is 0.5 to 200 ppm as solid content to the system.
Preferably it is 2 to 1100 pp. If the amount added is too small, the effect will be insufficient, and if the amount added is too large, it will be economically disadvantageous, so the above amount is the preferable range.

The surfactant of the present invention is effective when used alone, but it may also be used with agents conventionally used as water treatment agents, such as rust inhibitors, other corrosion inhibitors, chelating agents, dispersants, etc. It is also possible to use them together.

Concomitant drugs include amines, imidacillin, N-containing compounds such as amides, phosphoric acid esters, hydroxycarboxylic acids, lignin sulfonates, formalin condensates (salts) of aromatic sulfonic acids, and formalin condensates (salts) of melamine sulfonic acids. ), acrylic or methacrylic acid polymers (polycarboxylic acids), copolymers of olefin and maleic acid, inorganic salts such as nitrites, sulfates, and phosphates, aromatic carboxylates, aliphatic carboxylates , aminopolycarboxylate, thiourea, sulfosuccinic acids, polyethylene glycol, thioglycolic acid ester, polyethyleneimine, polyethyleneimide, benzotriazole, and the like.

〔Effect of the invention〕

When used as a scale inhibitor, the surfactant of the present invention exhibits excellent performance regardless of scale type. For example, it has excellent effects on scales such as calcium carbonate, calcium phosphate, magnesium hydroxide, and silica. Indicates boiler feed water, cooling water, seawater desalination (evaporation method),
Demonstrates excellent scale control performance in geothermal hot water, oil recovery, etc. It also shows excellent effects on various metals as a corrosion inhibitor.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail in Examples, but the present invention is not limited to these Examples.

Incidentally, scale inhibition and corrosion inhibition were adopted as measures showing the effects of the present invention.

Production Example 1 98 g of maleic anhydride (
1 mol) and 90 g of ion-exchanged water were added, and while stirring, 81.7 g of 49% caustic soda was added to neutralize the maleic acid. Thereafter, 30.8 g (0.35 mol) of sodium hypophosphite is added, and the temperature of the system is raised to 100°C. Then, 15.5 g of 35% hydrogen peroxide solution was added dropwise over 1 hour. During the dropwise addition, the temperature rises to 108° C., resulting in a reflux condition. After the dropwise addition, the mixture was further heated at 100° C. for 2 hours to complete the reaction, and an aqueous polymer solution with a solid content of 53.1% was obtained. After cooling, the water content was adjusted to obtain an aqueous solution of maleic acid/sodium hypophosphite=100/35 having a pH of 4.4 and a solid content of 50%. The monomer reaction rate of the obtained polymer was 97.1
%, and the reaction rate of sodium hypophosphite is 83.8
%Met. This reaction product is converted into an acid form using a cation exchange resin, and then evaporated to dryness under vacuum.

After dissolving the residue in dioxane and methyl esterifying it with excess diazomethane, the solvent was distilled off to obtain a chloroform solution, and the molecular weight was determined to be 420 by vapor pressure osmosis (VPO). The polymer has an average of 3 moles of maleic acid and 1 mole of hypophosphorous acid combined.

Production Example 2 The molar ratio of maleic acid and sodium hypophosphite was 100; 50.
The reaction was carried out in the same manner as in Production Example 1 except that 9.7 g of 35% hydrogen peroxide solution was used to obtain an aqueous polymer solution with a solid content of 56.1%. After adjusting the moisture content, p++4.5, solid content 5
A 0% aqueous solution of the reactant was obtained. Monomer reaction rate is 97.8
%, and the reaction rate of sodium hypophosphite was 85.2%. After methyl esterifying this compound, the molecular weight was measured to be 300 by the VPO method in chloroform solvent. The polymer is a condensation of 2 moles of maleic acid and 1 mole of hypophosphorous acid on average.

Production Example 3 Molar ratio of maleic acid and sodium hypophosphite is 100:20
The reaction was carried out in the same manner as in Production Example 1 except that the solid content was 51
．． A 4% aqueous polymer solution was obtained. Adjust the water content and adjust the pH to 4.
, 3. An aqueous solution of the reactant with a solid content of 50% was obtained. The monomer reaction rate was 93.2%, and the sodium hypophosphite reaction rate was 86.8%. The molecular weight was measured in the same manner as in Production Example 1 and found to be 590. The polymer is a condensation of 5 moles of maleic acid and 1 mole of hypophosphorous acid on average.

Production Example 4 98 g of maleic anhydride was placed in a flask equipped with a thermometer, stirrer, dropping funnel, nitrogen introduction tube, and reflux condenser.
Add 90 g of ion-exchanged water, and while stirring, add 81.7 g of 49% caustic soda to neutralize maleic acid. Then, 26.4g of sodium hypophosphite was added and the temperature of the system was raised to 100℃.
Increase the temperature to. After raising the temperature, an aqueous solution of 36 g of acrylic acid, 13.4 g of 30% caustic soda, and 5.9 g of sodium persulfate dissolved in 50 g of ion-exchanged water was added dropwise over 1.5 hours. After the dropwise addition, the mixture was further heated at 100° C. for 2 hours to complete the reaction, and an aqueous polymer solution with a solid content of 50.9% was obtained.

After cooling, adjust the moisture content p)l 4.4, solid content 50% maleic acid/acrylic acid/sodium hypophosphite = 1001
A 50/30 (molar ratio) aqueous solution of the reactants was obtained. The monomer reaction rate of the obtained polymer was 98.6%, and
The reaction rate of sodium hypophosphite was 85.9%. This reaction product is converted into an acid form using a cation exchange resin and then evaporated to dryness under vacuum. After dissolving the residue with dioxane,
After methyl esterification with excess diazomethane, the solvent was distilled off to form a chloroform solution, and the vapor pressure osmosis method (VP
When the molecular weight was measured by O), it was 690.

Production Example 5 Polymerization was carried out in the same manner as Production Example 4 except that 43 g of methacrylic acid was used instead of 36 g of acrylic acid, and maleic acid/methacrylic acid/sodium hypophosphite = 100150
/30 (molar ratio) copolymer aqueous solution (solid content 51.8
%) was obtained. The molecular weight of this product was 600. The water content was adjusted to obtain an aqueous solution of the reactant having a pH of 4.5 and a solid content of 50%.

Production Example 6 Polymerization was carried out in the same manner as Production Example 4 except that 72 g of acrylic acid was used instead of 36 g. 55.3%). The water content was adjusted to obtain an aqueous solution of the reactant having a pH of 4.3 and a solid content of 50%. When the molecular weight was measured in the same manner as in Production Example 4, it was 810.

Production Example 7 98 g of maleic anhydride and 90 g of ion-exchanged water were added, and while stirring, 81.7 g of 49% caustic soda was added to neutralize the maleic acid. After that, 17.6 g of sodium hypophosphite
, 47.4 g of sodium methallylsulfonate were added, and the temperature of the system was raised to 100°C. Then, 15.5 g of 35% hydrogen peroxide solution was added dropwise over 1 hour. After the dropwise addition, the mixture was further heated at 100° C. for 2 hours to complete the reaction.

In this way, an aqueous copolymer solution of maleic acid/sodium methallylsulfonate/sodium hypophosphite=100/30/20 (molar ratio) was obtained. The molecular weight of the obtained copolymer was 580.

Production Example Day 98 g of maleic anhydride and 90 g of ion-exchanged water are added, and while stirring, 49% caustic soda is added to neutralize the maleic acid.

Then, add 30.8g of sodium hypophosphite and
'C. After that, 36.5 g of allyl alcohol EO adduct (number of moles of EO added), 5.8 g of sodium persulfate.
An aqueous solution of 50 g of ion-exchanged water was added dropwise over 1.5 hours. Thereafter, the reaction is completed by heating at 100° C. for 2 hours.

In this way, maleic M/allylic alcohol EO adduct (EOP = 2)/sodium hypophosphite = 10
An aqueous copolymer solution with a molar ratio of 0/30/30 was obtained.

When the molecular weight was measured, it was 580.

Comparative Production Example 1 In Production Example 1, all experiments were conducted in the same manner as in Production Example except that 49% NaOH was not added.

In this way, p) 12.1, a reaction product aqueous solution with a solid content of 60.2% was obtained.The monomer conversion rate of this product was 49.2%, and the conversion rate of sodium hypophosphite was 50.6%. Both values were extremely low.

Comparative Production Example 2 In Production Example 1, 163.4 g of 49% NaOH
(?2 times the mole relative to leic acid) Production example 1 except for adding
The experiment was conducted in the same way.

In this way, an aqueous solution of plllo, 2 and solid content of 47.8% was obtained. It was a very low value.

Reference Example 1 A solution of 44 g of sodium hypophosphite dissolved in 100 g of reaction water with a molar ratio of acrylic acid and sodium hypophosphite of 4:1 at 75° C. was added with 1 portion of water (14 g of sodium persulfate per log g). 4g
was added dropwise over 2.5 hours. Five minutes after the start of dropping, 144 g of acrylic acid was added dropwise over 2 hours. After the dropwise addition was completed, the mixture was heated at 85° C. for 2 hours to complete the polymerization.

An aqueous reactant solution of acrylic acid/sodium hypophosphite=4/I (molar ratio) of the aqueous solution with a solid content of 25% thus obtained was obtained. The molecular weight of the polymer was 430.

Reference Example 2 Production of Sodium Polymaleate An aqueous solution containing 196 g (2.0 mol) of maleic anhydride was placed in a 4-IN flask equipped with a stirrer, a dropping funnel, and a reflux condenser, and 48% caustic soda aqueous solution 17
0 g was added to prepare a 50% by weight aqueous solution of maleic acid monosodium salt. The pH of the aqueous solution at this time was 3% concentration, 4
．． It was 1.

The temperature of the aqueous solution was raised to 100° C. while stirring, and 150 g of 35% hydrogen peroxide solution was added dropwise using a dropping funnel over 5 hours. Thereafter, the mixture was further stirred at 100° C. for 2 hours to complete the reaction.

In this way, an aqueous solution of polymaleic acid monosodium salt having a solid content of 39.3% and a pH of 5.2 was obtained.

The reaction rate of this product was 92.3% and the molecular weight was 910.

Example 1 In order to investigate the effect of the surfactant of the present invention obtained in each production example as a scale inhibitor, the following inhibition test was conducted.

To 150 g of calcium chloride dihydrate 0.176% aqueous solution,
300 t11 of a 1% aqueous solution of the surfactant polymer obtained in each production example was added, and 0
．． 150 g of a 168% aqueous solution was added. After adjusting the pH to 8.0, it was placed in a glass bottle, sealed tightly, and left to stand at 50°C for 6 hours. After cooling, the precipitate was then filtered through a 0.1 μ membrane filter, and the calcium concentration in the filtrate was analyzed by EDTA titration. Table 1 shows the results obtained.
It was shown to.

For comparison, when no scale inhibitor is used,
Results for polymaleic acid, commercially available sodium polyacrylate, and the reaction product of acrylic acid and sodium hypophosphite are also shown in Table 1.

Note) *: Molecular weight 3000 A: Ca concentration before heating B: Ca concentration in the filtrate after the test C: Ca concentration in the filtrate after the test without additives Example 2 Synthetic water 11 showing the following water quality was placed in a beaker. To this, a predetermined amount (as a solid content) of the surfactant of the present invention shown in Table 2 was added, and the water temperature was maintained at 50°C. Test piece 5 is placed in this water.
S-41 (45X20X 2mm) was immersed, and the water was stirred with a magnetic stirrer at 200 rpm.
It was kept in that state for 5 days.

However, during that time, the test water was replaced every two days.

Table 2 shows the corrosion rate after the test.

Synthetic water pH 8.0 Total hardness 200ppm (as CaCO,) Calcium hardness 150ppm (CaC (1+)) Alkalinity 150ppm (CaCO,
, etc.) Chloride ion 90ppm Sulfate ion 5Qppm Table 2 Example 3 The following test was conducted to investigate the scale suppression effect of the surfactant of the present invention obtained in each production example on a seawater heating system.

Using a testing machine capable of steam heating seawater circulating in a stainless steel pipe with an inner diameter of 6 mm to 110°C, artificial seawater with a concentration ratio of 2 times was circulated at 3201/Hr for 20 hours. The scale adhering to the pipes in the heater was dissolved by acid cleaning, and then quantified by atomic absorption spectroscopy to examine the inhibitory effects of each scale inhibitor. The results are shown in Table 3. In addition, the amount added in the table is the amount as solid content.

Table 3 Note) *: Represents the total amount of CaCO3 scale and Mg (Of() z scale) per unit area of heat exchanger tube.

Claims (1)

[Claims] Maleic acid or a salt thereof alone or a mixture thereof with a water-soluble monomer copolymerizable with it in the presence of hypophosphite,
An anionic surfactant containing a maleic acid polymer having a P-C bond in the molecule obtained by polymerizing with a polymerization initiator while maintaining the pH in an aqueous solution at 2.5 to 6.0.