JPH04166298A - Water treating agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to water treatment agents such as scale inhibitors and corrosion inhibitors that can prevent metal corrosion and scale formation in water systems.

[Prior art and problems to be solved by the invention] In general, in cooling water systems and boiler water systems of oil refining plants, chemical industry plants, air conditioning plants, etc., corrosion occurs on the surfaces of metal pipes, waterway walls, heat transfer surfaces of boilers, etc. This can lead to the formation of corrosion and scale, which can reduce efficiency and even cause blockages, so great care is always taken to prevent corrosion and scale formation.

Conventionally, polyacrylates, polymaleic acids, and phosphoric acid-based compounds have been used in such aqueous systems to prevent scale, for example.

However, when using polyacrylate as a scale inhibitor, for example, in highly hard water systems with high calcium hardness, it not only reacts with calcium ions in the water to form insoluble salts, but also reduces scale prevention ability. In some cases, it may even cause the occurrence of

Furthermore, when used as a water treatment agent, a maleic acid homopolymer or copolymer has an excellent scale inhibiting effect, but has drawbacks such as an insufficient effect as a corrosion inhibitor.

On the other hand, in order to prevent metal corrosion in the water system mentioned above,
Chromates and phosphates have been used. However, chromate is subject to emission regulations due to its toxicity. Additionally, there is a growing trend towards regulation of phosphates as they cause eutrophication in closed water bodies.

[Failure to solve the problem]

As a result of intensive research to solve such conventional problems, the present inventors discovered that polyepoxysuccinic acid or its salt has excellent performance particularly as a scale inhibitor and corrosion inhibitor, and completed the present invention. reached.

That is, the present invention is based on the following formula % formula % (1) c where n represents an integer of 2 to 40, and Represents a cation. ] The present invention provides a water treatment agent characterized by comprising polyepoxysuccinic acid or a salt thereof.

The polyepoxysuccinic acid or its salt represented by the general formula (1) of the present invention can be obtained by a conventionally known method.

For example, maleate is epoxidized with hydrogen peroxide using sodium tungstate as a catalyst to give epoxysuccinate (G, B, Payne).

P, H, Williams, J, Org, Chem.
, 24.54 ('59)).

Next, after converting the epoxy succinate into a methyl or ethyl ester, ring-opening polymerization is performed in a solvent-free system or in an inert solvent, and the resulting polymer is hydrolyzed to form a compound represented by the general formula (1). Polyepoxysuccinic acid is obtained. Further, in this polyepoxysuccinic acid, some or all of the carboxylic acid groups may be converted into a salt form using a monovalent metal cation, a divalent metal cation, an ammonium ion, or an organic amine cation.

The water treatment agent of the present invention can be applied to all types of water such as pure water, soft water, tap water, and industrial water, and the concentration used is determined depending on the purpose, but generally the active ingredient is 0.
1 to 500 ppm, especially 0.5 to 200 ppm
It is preferable that Further, the pH range of the target aqueous system is not particularly limited, but it is generally pH 6 to 14, preferably pF 16 to 12.

Specific examples of target water systems for the water treatment agent of the present invention include boiler water systems, open or closed circulation cooling water systems, overflow cooling water systems, brine water systems, some converter dust collection water systems, and dry water systems such as blast furnace converters. Examples include cooling water systems in pits, ammonia distillation tower water systems in coke factories, etc., incineration ash water systems in municipal waste cleaning plants, and seawater desalination equipment.

The water treatment agent of the present invention is effective when used alone, but it can also be used with agents conventionally used as water treatment agents,
For example, it is also possible to use a rust preventive agent, another anticorrosive agent, a chelating agent, a dispersant, etc. in combination.

Concomitant drugs include amines, imidacillin, N-containing compounds such as amides, phosphoric acid esters, hydroxycarboxylic acids, lignin sulfonates, formalin condensates of aromatic sulfonic acids (salts), melamine sulfonic acid formalin condensates (salts), etc. ), acrylic acid or methacrylic acid polymers (polycarboxylic acids), copolymers of olefin and maleic acid, inorganic salts such as nitrites, sulfates, and phosphates,
Examples include aromatic carboxylic acid salts, aliphatic carboxylic acid salts, aminopolycarboxylic acid salts, 1,000 urea, sulfosuccinic acids, polyethylene glycol, thioglycolic acid esters, polyethyleneimine, polyethyleneimide, and henzotriadur.

[Action and effect of the invention]

Since the water treatment agent of the present invention has a large amount of ether groups and carboxyl groups in its molecules, its adsorption to scales, pipe walls, etc. is improved. Therefore, it has improved scale prevention ability and corrosion inhibition ability, and is also excellent in toxicity and biodegradability, so it has the advantage of having little negative impact on the environment.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Synthesis Examples and 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.

Synthesis example of polyepoxy succinate Payne et al. (J, Org, Chem, 2A,
Epoxy succinate was synthesized according to the method of 54 ('59)).

That is, maleic anhydride 22 was placed in a flask equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube, and a reflux condenser.
3 g and 320 g of ion-exchanged water were added and dissolved. After dropping 293g of 50% caustic soda into this liquid, the temperature of the liquid was lowered to 6.
It was set to 0°C. 7.8g of sodium tungstate in this liquid
After that, 270 g of 30% hydrogen peroxide solution was added. At this time, the flask was cooled with ice, and the temperature of the reaction solution was adjusted to 60-88℃.
The temperature was maintained at 0°C. Thereafter, the mixture was maintained at 60°C for 1 hour to obtain sodium epoxysuccinate.

Next, this sodium epoxysuccinate was made into an acid form according to the method of Payne et al., and then reacted with an excess amount of ethyl orthoformate to obtain diethyl epoxysuccinate.

After putting 21 g of epoxysuccinic acid diethyl ester into a flask equipped with a thermometer, a stirrer, a nitrogen introduction tube, and a dehydration tube, and adding 0.3 g of boron trifluoride diethyl ether complex,
The temperature was maintained at 100°C for 148 hours. The obtained liquid was reprecipitated with hexane, dried, and then alkaline hydrolyzed with caustic soda (80''C, 24 hours) to obtain sodium polyepoxysuccinate.

Example 1 The following test was conducted to examine the effectiveness of the water treatment agent of the present invention as a scale inhibitor.

To 150 g of calcium chloride dihydrate 0.176% aqueous solution,
300 μl of an aqueous solution containing 1% of the active ingredient of the compound of the present invention shown in Table 1 was added, and 0.0 μl of sodium bicarbonate was added.
150 g of a 168% aqueous solution was added. After adjusting the pH to 8.0, it was placed in a glass bottle, tightly stoppered, and left at 60°C for 6 hours. After cooling, the precipitate was filtered through a 0.1 μ membrane filter, and the calcium concentration in the filtrate was determined. was analyzed by EDTA titration. The results obtained are shown in Table 1.

For comparison, Table 1 also shows the results for commercially available polymaleic acid, commercially available sodium polyacrylate, and tartaric acid as scale inhibitors.

Table 1 Note) A: Ca concentration before heating B: Ca concentration in the filtrate after the test C: 1 degree of Ca 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 were added the water treatment agent of the present invention and a comparative sample in predetermined amounts (as solid content) shown in Table 2, and the water temperature was maintained at 50°C. Carbon steel specimen 5S-41 (45x20x2 m
m) and soak the water in a magnetic stirrer for 20 minutes.
It was stirred by Orpm and kept in that state for 10 days.

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

Table 2 shows the corrosion rate after the test.

Synthetic water p) + 8.0 Total hardness 200 ppm Calcium hardness 150 ppm (as CaCOs) Alkalinity 150 ppm (as CaCOi) Chloride ion 90 ppm Sulfate ion 60 ppm Table 2 Example 3 For seawater heating system The following tests were conducted to investigate the scale suppression effect.

Using a testing machine capable of steam heating seawater circulating in a stainless steel pipe with an inner diameter of 6 m to 110°C, artificial seawater with a concentration factor of 2 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) *: CaCO5 scale and M per unit area of heat exchanger tube
g (0) 1) represents the total amount on the z scale.

Claims (1)

[Claims] The following formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (1) [In the formula, n represents an integer from 2 to 40, and X and Y are hydrogen atoms, monovalent or divalent metal atoms, ion, ammonium ion or organic amine cation. ] A water treatment agent comprising polyepoxysuccinic acid or a salt thereof.