JPS632987B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for stabilizing a polyacrylamide-based polymer compound solution. Water-soluble polymer compounds, such as polyacrylamide-based polymer compounds, are generally easy to polymerize, and extremely high molecular weight products can be obtained under relatively mild conditions. Utilizing the solution properties of this polyacrylamide-based polymer compound, it has been put to practical use in a wide variety of fields, including water treatment agents, soil conditioners, fiber processing agents, oil-water separation agents, and oil recovery agents. On the other hand, the drawback is that it tends to decompose. For example, if an aqueous polyacrylamide solution is left at room temperature, it may lose the viscosity it had when it was prepared within a relatively short period of time. This phenomenon is noticeable at high temperatures or when transition metal salts such as Fe ²⁺ or Co ²⁺ are present in the solution, and in extreme cases, the viscosity may become as high as that of water. Various studies have been made to solve the above problems. For example, in US Pat. No. 3,337,356 and US Pat. No. 3,493,539, UV absorbers are used to prevent deterioration. On the other hand, oil recovery agents are a field that utilizes the polymer viscosity behavior of polyacrylamide compounds. However, since the polymer remains in the high-temperature oil layer for a long period of time, deterioration of the polymer becomes a problem. The decrease in viscosity of the aqueous solution of the polymer in this case is thought to be due to a radical reaction involving enzymes dissolved in the water and transition metal ions such as Fe ²⁺ and Co ²⁺ . From this, it is known that deterioration can be suppressed by adding Na ₂ So ₃ , NaHSO ₃ , thiourea, or the like. (U.S. Patent No. 3235523, U.S. Patent No. 3234163
(See No.) Apart from this, formaldehyde and various alcohols exhibit deterioration inhibiting effects in the presence of oxygen. (Journal of Petroleum
Technology, Aug. 1981, P1513~) In addition, the effects of stabilizers such as S/N-containing compounds (for example, 2-mercaptobenzothiazole and 2-mercaptobenzothiazole) are also known. (Special Publication No. 58-47414, Special Publication No. 44-26645 and
(Refer to No. 55-65696) These conventional techniques are not yet sufficient in terms of their stabilizing effect; even if they had a stabilizing effect, a large amount of stabilizer had to be added to the polymer; The effect was not sufficient for transition metal ions such as Fe ²⁺ and Co ²⁺ . The present inventor has arrived at the present invention as a result of intensive research in order to solve the problems of these conventional techniques. That is, the present invention provides a method for stabilizing a water-soluble polymer compound solution, which is characterized by blending an amine salt of 2-mercaptobenzothiazole into a polyacrylamide-based polymer compound solution. Examples of the amine of the 2-mercaptobenzothiazoleamine salt of the stabilizer of the present invention include alkyl amines and cyclic amines. By using an amine salt, more stabilization can be achieved than the commonly used alkali salts and ammonium salts. The effect is particularly remarkable at high temperatures of 70°C or higher. this is,
This is because ordinary alkali salts do not have reducing properties, and ammonium salts dissipate from the solution at high temperatures, whereas amine salts do not. The polyacrylamide-based polymer compound as used in the present invention refers to an acrylamide polymer, a copolymer containing an acrylamide moiety, or a mixture thereof. Specifically, the monomer that is one of the components constituting the copolymer includes methacrylamide,
(meth)acrylic acid (salt), acrylonitrile, 2
- Hydrophilic monomers such as acrylamide-2-methylpropanesulfonic acid (salt), di-methylaminoethyl methacrylate, acrylic acid lower alkyl ester, and vinylpyridine. In addition, other functional groups can be introduced not only through copolymerization reactions but also through polymer reactions such as hydrolyzing 50% or less of the amide groups in the acrylamide polymer, methylolation, or mannitzization. It also includes those who have. In the present invention, the concentration of the polyacrylamide polymer compound solution is about 0.0001 to 20% by weight aqueous solution, preferably 0.001 to 5% by weight. Next, the use of the stabilizer in the present invention is based on 100 parts by weight of the polyacrylamide polymer compound.
The amount is preferably from 0.01 to 20 parts by weight; if it is less than 0.01 parts by weight, the effect of the stabilizer cannot be exhibited, and if it exceeds 20 parts by weight, no economic effect can be expected. The stabilizer of the present invention can be used in combination with guanidine compounds such as 1,3-diphenylguanidine, di-o-tolylguanidine, and 1-o-tolyl biguanide, ethylenediaminetetraacetic acid (hereinafter referred to as EDTA), its alkali salts, ammonium salts, etc. can. The water used for the polymer solution is mainly water with relatively high salt concentration, such as seawater or geological formation water.
If necessary, insoluble matter filtration, bacterial sterilizers, anticorrosive agents, etc. can be added. Next, the present invention will be specifically explained using examples. (The screen factor measured in the following examples is one of the indicators indicating the viscosity of the polymer aqueous solution, and it correlates with the viscosity flowing in the actual oil layer.The screen factor is approximately 30 ml.
of fluid volume and five 0.25 inch diameter
Using a screen viscometer consisting of a 100 mesh stainless steel wire gauze, it is expressed as the ratio of the transit time between the polymer aqueous solution and its solvent. For measurements, each polymer solution was stored in thermostats at 50°C, 70°C, and 80°C, and the measurement temperature of the polymer solution was set at 25°C for daily measurements. Note that dissolved oxygen was not removed. ) The molecular weights of the various polymers used in the present invention were determined using the following formula. [η] = 3.73×10 ^-4 M ^0.66 [η] = Intrinsic viscosity in 1N sodium nitrate (30°C) M = Molecular weight Example 1 Acrylamide polymer with a molecular weight of approximately 17 million
In an aqueous solution consisting of 500 ppm, 3% sodium chloride, and 0.03% calcium chloride, 2-mercaptobenzothiazole (hereinafter abbreviated as M) alone, 2-
Cyclohexylamine (hereinafter abbreviated as MH) of mercaptobenzothiazole alone was added and dissolved at 15 ppm relative to the system, and the stability over time at 80°C was measured. The results are shown in Table 1 below.
It was as follows. Example 2 500 ppm of acrylamide polymer with a molecular weight of about 10 million and a partial hydrolysis rate of 20 mol%, 3 sodium chloride
% and calcium chloride 0.03%, MH, MH/1-0-tolylbiguanide =
1/1, MH/EDTA = 1/1 blending ratio was added at 10 ppm based on the system, dissolved, stored at 70°C, and measured under the above conditions. The results are shown in Table 2. Example 3 500 ppm copolymer with a molecular weight of approximately 7 million, consisting of 80 parts by weight of acrylamide, 15 parts by weight of sodium acrylate, and 5 parts by weight of sodium 2-acrylamide-2-methylpropanesulfonate, 3% of sodium chloride, and 0.3% of calcium chloride. In an aqueous solution consisting of 2-mercaptobenzothiazole, Na
The triethanolamine salt of 2-mercaptobenzothiazole was added at 50 ppm, sealed in a sealed tube, stored at 90°C, and the results measured under the above conditions are as shown in Table 3. Ta. Comparative Example 1 Copolymerization with a molecular weight of 11 million consisting of 85 parts by weight of acrylamide and 15 parts by weight of sodium acrylate.
In an aqueous solution consisting of 1000 ppm, 3% sodium chloride and 0.03% calcium chloride, M alone, MH
Alone, MH/di-O-tolylbiguanide = 1/
1. Add 20 ppm of MH/EDTA = 1/1 to the sample, store at 50°C, 70°C, and 80°C, and measure under the above conditions. The results are shown in Table 4. Ta.

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Claims (1)

[Claims] 1 Into the polyacrylamide polymer compound solution,
A method for stabilizing a polyacrylamide-based polymer compound solution, which comprises blending an amine salt of 2-mercaptobenzothiazole.