JPS61153198A - Anti-scaling agent - Google Patents

Abstract

PURPOSE:To obtain the titled anti-scaling agent exhibiting a remarkable synergetic effect by copolymerizing maleic anhydride and an olefin having a specified number of carbon atoms in a specified ratio, and using the hydrolyzate of the copolymer jointly with a phosphonic acid compd. CONSTITUTION:A copolymer having 1,000-10,000 number average mol.wt. is prepared by copolymerizing 70-95mol% maleic anhydride and 5-30mol% 5C olefin (e.g., cyclopentene). The hydrolyzate of the copolymer and a phosphonic acid compd. (e.g., 1-hydroxyethylidene-1.1-diphosphonic acid) are incorporated into an anti-scaling agent as effective components. The amt. of the anti-scaling agent to be used is regulated usually to 0.1-1,000ppm or preferably to 0.5-50ppm. By such a method, the anti-scaling agent which is excellent in comparison with the agent obtained by the conventional technique can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel scale inhibitor, and more particularly to a scale inhibitor comprising a specific polycarboxylic acid and a phosphonic acid compound.

(Prior art) Equipment that handles water (e.g. heat exchangers, cooling water towers, boilers, desalination equipment, seawater desalination equipment, geothermal power generation equipment, membrane separation equipment, cleaning equipment 1. Crude oil recovery equipment, pipelines, etc.) ) The water used in water contains various impurities ◇
Among them, cations such as calcium ions, magnesium ions, and barium ions, and anions such as carbonate ions, bicarbonate ions, sulfate ions, phosphate ions, and silica ions, which are present in the bath, are affected by the temperature and pressure of the system, 1) H, etc. The impact produces water-insoluble salts that adhere to and accumulate on the surface of equipment, creating scale. In addition, various suspended substances (e.g., earth, sand, clay, organic matter, etc.) are present in the water, and these accumulate as sludge precipitates in the equipment. Because it reduces the thermal conductivity of the equipment and causes corrosion of the equipment,
Various scale inhibitors have been developed in the past. Examples include carboxylic acid-based polymer compounds such as polyacrylic acid, polymaleic acid, and olefin-maleic anhydride copolymers (% Publication No. 55-20475, No. 54). -299
98 etc.), a mixture of polyacrylic acid and phosphonocarboxylic acid (JP-A-52-114481), inorganic phosphoric acid, phosphonic acid, organic phosphoric acid ester or polyvalent metal and olefin-maleic anhydride copolymer However, under recent harsh conditions of use, even these scale inhibitors still cannot be said to have sufficient performance, and better The development of high-performance scale inhibitors is strong (a much-desired friend).

(Problem to be solved by the invention) Therefore, the present inventors developed a scale inhibitor that surpasses the conventional technology (As a result of intensive studies, a copolymer made by copolymerizing maleic anhydride and olefin t having 5 carbon atoms at a specific ratio) The inventors have now completed the present invention by discovering that when a hydrolyzate of a combination and a phosphonic acid compound are used together, a remarkable synergistic effect is exhibited as a scale inhibitor.

(Means for Solving the Problems) Thus, according to the present invention, the number average molecular weight of 1.000 to I
A scale inhibitor containing as active ingredients a hydrolyzate (A) of a copolymer of 70 to 95 mol of maleic anhydride having a molecular weight of Q,000 and 75 to 30 mol of an olefin having 5 carbon atoms and a phosphonic acid compound (B). provided.

The copolymer used in the present invention has 70 maleic anhydride units.
~95 molar, preferably 75-90 molar and 5 carbon atoms
5 to 50 moles of olefinic units, preferably 10 to 2
and has a number average molecular weight (measured by VPO) of 1,000 to 10,000, preferably 1.20.
It is a hydrolyzate of a copolymer having 0 to s, ooot-.

As the olefin having 5 carbon atoms, pentene-
Examples include 1, pentene-2,2-methylbutene-1,2-methylbutene-2, cyclopentene, 7-a-pentadiene, and isoprene, and two or more types can be used in combination as necessary. Among them, chain monoolefins show excellent performance.

Such copolymers can be produced by various known methods. For example, after carrying out a polymerization reaction in a solvent using a radical initiator at an appropriate temperature (for example, in the range of 30 to 200°C), the solvent is separated. Obtained by removing. The hydrolyzate used in the present invention may be simply hydrolyzed with water, but it may also be hydrolyzed in the presence of a base to form a water-soluble salt.◎ Water-soluble salt As salts for production, alkali metal salts such as sodium, potassium, etc., and amine salts such as ammonia, triethylamine, triethanolamine, etc. are used, and among them, sodium salts are preferred because of their economic efficiency. Ru.

The molar ratio of maleic anhydride and C, olefin in the copolymer is an important requirement of the present invention; if the maleic anhydride is less than 70 mol, the scale prevention effect of calcium carbonate will be insufficient, and if it exceeds 95 mol, The scale prevention effect of calcium sulfate is insufficient.

The other essential component, the phosphonic acid compound, has 0-
A compound containing at least one phosphate group due to a P bond or a water-soluble salt thereof; specific examples include aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra(
Examples include methylenephosphonic acid) and 2-phosphono-butane-tricarboxylic acid (1,2,4). Two or more of these phosphodiacids can be used in combination if necessary. As their water-soluble salts, alkali metal salts such as sodium and potassium salts, and amine salts such as ammonia, triethylamine, triethanolamine, etc. are used. Among them, the sodium salt is preferred from the viewpoint of economical efficiency, etc. The ratio of the copolymer hydrolyzate to the phosphonic acid compound is about 90:10 to 10:90 (weight ratio), preferably about 70: 50-50:70 (weight ratio) ◎These two components are usually mixed beforehand, but they may be added separately to the system to which they are added.The amount used in the system is as follows:
Usually 11~11000pp, preferably α5~so
It is ppm.

(9) As long as the effects of the present invention are not essentially impaired, commonly used agents such as other scale inhibitors, alkaline agents, anticorrosive agents, bactericidal agents, etc. may be appropriately used in combination. Thus, according to the present invention, it is possible to obtain a scale inhibitor that is superior to that of the prior art. Parts and parts in the examples (key 9 unless otherwise specified)
It is based on weight.

Example 1 Scale formation and adhesion prevention effect (test method) An aqueous solution containing a predetermined amount of 11 scale inhibitors and prepared under the following conditions was placed in a separable flask equipped with a reflux device containing a carbon steel test piece. The mixture was heated under reflux for 24 hours. The generated scale T - After each house was separated, the amount of metal ions in the F solution was determined by titration, and the scale prevention efficiency was calculated according to the following formula. ◇ Also, the amount of scale attached to the test piece was weighed and the amount of scale attached was measured. The results are shown in Table 1〇(
Adjustment conditions] ul calcium carbonate 100 PpII% pH 10.2 (
2) Calcium sulfate: 6800 ppm, pH: 7.8 or higher The results show that the product of the present invention is effective as a scale formation and adhesion inhibitor, as it is effective with a small amount of addition.Example 2 Sludge accumulation prevention effect (Test method) Clay, anti-scaling agent, and water were mixed as follows (mixed and dispersed by shaking for 3 minutes using a shaking pigment dispersion machine. After that, it was left to stand at 25°C, and the supernatant liquid was added at regular intervals. The light transmittance of the tungsten lamp was collected (mm/mm 0)
was measured. The effectiveness of preventing sludge accumulation was determined from this change in light transmittance.

The results are shown in Table 2.

(Formulation) Clay (UW90, manufactured by Kngrl Har6) 150 parts Water 500 Scale inhibitor 0.0015 Table 2 The product of the present invention has a small change in light transmittance, so it has a strong sludge dispersion effect (sludge accumulation prevention It can be seen that the effect is excellent.

Claims (1)

[Claims] 1. A hydrolyzate of a copolymer of 70 to 95 mol% of maleic anhydride having a number average molecular weight of 1,000 to 10,000 and 5 to 30 mol% of an olefin having 5 carbon atoms (A) and a phosphonic acid compound (B) ) as an active ingredient.