JPH0478493A - Scale inhibitor - Google Patents

Abstract

PURPOSE:To obtain a scale inhibitor having a significant effect especially to silica-based scale by incorporating a specified compd. having a bisphenol type epoxy compd. as the skeleton and an alkylene oxide chain. CONSTITUTION:This scale inhibitor contains a compd. having a bisphenol type epoxy compd. as the skeleton and an alkylene oxide chain and represented by formula I (where R1 is a group represented by formula II, R2 is a group represented by formula III or IV, X shows formula V (bisphenol A type), formula VI (bisphenol S type) or formula VII (bisphenol AF type), n is an integer of 0-12, each of m1 and m2 is an arbitrary integer of >=1 but 2<=m1+m2<=1,000 and each of l1-l7 is an arbitrary integer of >=1 but 50<=l1+l2+l3+l4+l5+l6+ l7<=1,000-). This scale inhibitor has superior power especially to silica-based scale as well as to Ca-based scale and Mg-based scale.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a water-based scale inhibitor.

<Conventional Technology> In recent years, from the perspective of effective use of water resources, recycling of cooling water and the like has been progressing in factories and the like in order to reduce the amount of water used. Accordingly, water becomes highly concentrated, and as a result, in such water systems, so-called scale components such as calcium, magnesium, and silica are concentrated, causing problems such as scale adhesion to heat transfer surfaces such as heat exchangers. . When scale builds up, it not only reduces the heat exchange rate but also causes problems such as tube blockage and corrosion, which in the worst case can lead to interruption of operation. Such scale failures occur not only in cooling water systems, but also in boiler water systems and geothermal power generation water systems. In particular, silica scale is hard and has low thermal conductivity, which is a big problem.

Conventionally, phosphorus compounds, polyacrylic acid, polymaleic acid, or water-soluble salts thereof have been used as agents to prevent such scale, but these alone have little effect on silica scale. In addition, quaternary ammonium compounds (Japanese Unexamined Patent Publication No. 110398/1982), polyacrylamide (
JP-A No. 61-107997), glyoxal (
Although JP-A-61-293597) and polyalkylene oxide compounds (JP-A-62-43758, JP-A-59-29357) have been proposed, their effects are not sufficient.

<Problems to be solved by the invention> The present invention solves the problems of the conventional techniques, and has a scale prevention effect superior to that of the conventional techniques.
The purpose is to develop a scale inhibitor that is particularly effective against silica scale.

Means for Solving the Problems> The scale inhibitor according to the present invention, which has been made to achieve the above object, has a bisphenol type epoxy compound as a backbone and has an alkylene oxide chain and has a general formula (I) H-(Ri). *1-(Ri)az-(Rz)s+-
.

0J-0-CHt-CH-CHx-(1)0-(Rt)
a s-)! 0-(Ri)a a-(Rz)at-(Ri)j? -H
(In the formula, R7 is a group represented by -CH2-CHz-0-,
R2 is CHe CH.

A group represented by -CH□-CH-0- or -CH-CH,-0, X is H5Q-C-■ (bisphenol A type) or CH.

CF3 ■-C-■ (bisphenol AF type), CF.

n is an integer from O to 12, ml, and Inz are each 2
Any integer greater than or equal to 1 in the range ≦m1+mz≦1.000,! , ~l, are each 50≦1. +1. +p3+
1 in the range of 14+Ig, +16+It≦1,000
It is characterized by containing a compound represented by (any integer above).

The above compound alone exhibits unprecedented scale prevention effects, but it can also be used in conjunction with acrylic acid polymers and copolymers, maleic acid polymers and copolymers, and sulfonic acid polymers and copolymers. Even better effects can be obtained when a scale inhibitor containing at least one selected from the group consisting of:

The compound of the present invention is prepared by combining an epoxy oligomer and a polyethylene oxide-polybropylene oxide block copolymer in the presence of a caustic catalyst at a temperature of 130 to 17°C.
The reaction was carried out at 0°C, and then ethylene oxide was added to the reaction product in the presence of an alkali catalyst at a temperature of 120 to 18°C.
It can be obtained by reacting at 0°C. As the epoxy oligomer to be used, any of bisphenol A type, bisphenol S type, and bisphenol AF type can be used, but type A is the most common. Bisphenol A type is Ebicoat #828, #10Q1, #1004, #100
7, #1008 (Showa Shell Chemical), Ebitoto YD~128, YD-011, YD-014, YD-0
17, YD~019 (manufactured by Tobu Kasei Co., Ltd.), and any of these can be used, but among them, those in which the value of n in the above formula (I) is n = 0 to 4 are used. I especially like L7. In addition, the polyethylene oxide-polybropylene oxide block copolymers used are Broronisokushi-43, L-63, L-103 (manufactured by Asahi Denka), New Ball PE-63, PE-73, PE-
It is commercially available under trade names such as 83 (manufactured by Sanyo Chemical), and any of these can be used.

In addition, acrylic acid polymers and copolymers, maleic acid polymers and copolymers, sulfonic acid polymers and copolymers used in combination include polyacrylic acid, polymaleic acid,
Styrene sulfonic acid (homopolymer), acrylic acid-
There are water-soluble salts such as acrylamide copolymer, methacrylic acid-acrylamide copolymer, maleic acid-isobutylene copolymer, maleic acid styrene sulfonic acid copolymer, and their sodium salts, potassium salts, etc., and one of these or Use two or more types together. These polymers can be easily polymerized by known methods. The molecular weight of these polymers is suitably from 200 to 100,000, preferably from 500 to 3oooo.

When the above polymer or copolymer is used in combination with the compound of formula (1), each may be added to the water separately, but each drug may be mixed in advance at a predetermined ratio to form a single agent. It is convenient to do so because handling and addition operations become easier.

The mixing ratio when mixing each drug to form a single drug is calculated using the formula (1
) compound polymers and/or copolymers in a weight ratio of 9:1 to 4:6 (weight ratio, same hereinafter), preferably 8:2 to 5:5.

Further, the amount of the scale inhibitor of the present invention to be added is determined when the compound of formula (I) is used alone, and when the scale inhibitor contains the above polymer and/or copolymer in addition to the compound of formula (1). In either case, the concentration in water is 1.
from 5 to 500 ■/l, preferably from 5 to 200 ■/l
It is best to set the amount so that It may be added in either liquid or solid form, but in order to ensure accuracy in the amount added, it is better to add in liquid form.

Incidentally, the scale inhibitor of the present invention is a pH adjuster such as storium hydroxide or sodium carbonate, a phosphoric acid compound, a hexametaphosphoric acid compound, a phosphoric acid compound, or a salt thereof such as a phosphonic acid compound, a zinc compound, or a molybdenum compound. metal compounds that are usually used as anti-corrosion agents, azole compounds such as benzotriazole and tolyltriazole, chlorine compounds, quaternary ammonium compounds, organic nitrogen sulfur compounds, and disinfectants such as aldehyde compounds. There is no problem in using them together or in combination.

<Function> The compound represented by the general formula (1) having a bisphenol type epoxy compound skeleton and an alkylene oxide chain is disclosed in the aforementioned Japanese Patent Publication No. 62-43758 and Japanese Patent Application Laid-Open No. 1983-1989.
Compared to polyalkylene oxide compounds such as the one proposed in Publication No. 29357, the arrangement of hydrophobic groups and parent groups is significantly different, and this unique structure prevents not only calcium-based and magnesium-based precipitates in water. In particular, it is thought that it can strongly physically adsorb to the surface of silica-based precipitates and suppress crystal growth, thereby preventing scale formation.

In addition, acrylic acid polymers and copolymers, maleic acid polymers and copolymers, and sulfonic acid polymers and copolymers used in combination with the above compounds are particularly effective against the surface of calcium and magnesium precipitates. Because of their strong adsorption, by using both compounds together, it is possible to suppress the crystal growth of not only calcium-based and magnesium-based precipitates, but also reaction precipitates of calcium and silica, and magnesium and silica, resulting in an even better effect synergistically. It is thought that it will be effective.

<Example> The present invention will be explained in detail below.

Example 1 A heat exchanger with a heat transfer area of 0.3- and a retained water amount of 0°8-
Using an experimental open circulation type cooling device, operation was carried out under the following conditions so that the concentration ratio of the circulating water was increased to 7 times while maintaining the specified amount of the specified chemicals.

Operating conditions Heat exchanger inlet temperature 30℃ Heat exchanger outlet temperature 45℃ Flow rate 1.0m/s Makeup ice water quality pH 6,8 Electrical conductivity 180a/cd Silica 61■s i Oz/ 'Calcium 35N Ca CO:l / I! Magnesium: 9.0 mgCaC0,/1 After the operation was completed, the silica concentration and calcium concentration of the circulating water were analyzed.

The type of pharmacological analysis used is shown in Table ml, (2), and the experimental results are shown in Table 2.

Table 2 Experimental Results Table 1-(21 Chemicals Used As seen in Table 2, the silica concentration in the circulating water to which the scale inhibitor of the present invention was added was significantly higher than in the comparative example. This means that there is little precipitation or adhesion of silica scale on the heat transfer surface of the heat exchanger used, and it can be seen that the scale inhibitor of the present invention exhibits excellent effects.

Example 2 It has a heater with a heat transfer area of 100 d and has a water capacity of 100! Water of the following quality, which had been prepared by concentrating industrial water in advance, was placed in a circulation device, and a specified amount of a specified chemical was added thereto, and the system was operated for 14 days.

Circulating water quality pH 7,8 Electrical conductivity 1550ha/- ``')': h l 85aS ioz/l Calcium 410 ■ca CO:I/ 1Magnesium 91 [Ca CO,/ 1 Adheres to the heater after completion of operation The adhesion rate of scale was measured.

The results are shown in Table 3 along with comparative examples. Note that in Table 3, the same drug symbols as in Table 1 above indicate the same drugs.

Table 3 shows that the scale inhibitor of the present invention exhibits excellent effects.

<Effects> As explained above, the scale inhibitor of the present invention exhibits excellent preventive power not only against calcium-based and magnesium-based scales but also particularly against silica-based scales25, and prevents a decrease in the heat exchange coefficient of the heat transfer surface. Not only that, but it also prevents the occurrence of various disorders and has a great impact on industry.

Claims (1)

[Scope of Claims] 1. A scale inhibitor containing a compound represented by the following general formula (I) having a bisphenol-type epoxy compound skeleton and an alkylene oxide chain. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R_1 is a group represented by -CH_2-CH_2-O-, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲Mathematical formulas, chemical formulas, There are tables, etc. ▼ For the group represented by,
Type) or ▲Mathematical formulas, chemical formulas, tables, etc.▼(Bisphenol S
Type) or ▲Mathematical formulas, chemical formulas, tables, etc.▼(Bisphenol A
F type), n is an integer from 0 to 12, m_1 and m_2 are each 2≦m
Any integer greater than or equal to 1 in the range of _1+m_2≦1,000, l_1 to l_7 are each 50≦l_1+l_2
+l_3+l_4+l_5+l_6+l_7≦1,00
(any integer greater than or equal to 1 within the range of 0) 2, a compound represented by the general formula (I), an acrylic acid polymer and copolymer, a maleic acid polymer and copolymer, and a sulfone The scale inhibitor according to claim 1, which contains at least one selected from the group consisting of acid polymers and copolymers. 3. The scale inhibitor according to claim 1 or 2, wherein the scale is a silica scale.