JP3291522B2 - Acrylamide-based polymer stabilizer and stabilized polymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stabilizer for an acrylamide polymer and a stabilized acrylamide polymer composition obtained by adding the stabilizer.

[0002]

2. Description of the Related Art Acrylamide-based polymers are polymer flocculants, papermaking chemicals, electrolytic refining additives, oil recovery chemicals,
It is used in many fields such as a thickening agent for drilling mud and is often used as an aqueous solution. Acrylamide-based polymers have received promising reputations in these diverse fields of application, but the greatest drawback of this polymer is that it is prone to degradation in aqueous solutions.
For example, when an acrylamide-based polymer aqueous solution is left at room temperature, a phenomenon in which the viscosity of the aqueous solution significantly decreases from the initially indicated value within a short period of time is observed, and this phenomenon is relatively accelerated at high temperatures, and in severe cases, It may not be possible to use it for the intended application.

[0003] One use of the acrylamide-based polymer aqueous solution is as a liquid for injection for the secondary and tertiary recovery of crude oil, but the temperature of the underground oil reservoir is often 40 ° C or higher, and in some cases, It may be 100 ° C or higher. The injection liquid for crude oil recovery is required to be stable under such conditions for a long period of time. For this reason, various heat stabilizers for acrylamide polymers, such as benzotriazole, 2-mercaptobenzothiazole, metal salts of dimethyldithiocarbamic acid, thiourea, 2-mercaptobenzimidazole, and methionine have been proposed.

[0004]

However, although various stabilizers which have been studied so far have a low stabilizing effect or exhibit a stabilizing effect under specific conditions, acrylamide-based polymers can be used in various atmospheres. Because a specific acrylamide polymer is not always added to an aqueous solution in a specific atmosphere, a polymer with a specific stabilizer is always stable. However, it is practically difficult to change the stabilizer according to the atmosphere each time. Therefore, no effective stabilizer has been found, and a more effective stabilizer has been found. Is in high demand.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an acrylamide polymer stabilizer and a stabilized acrylamide polymer composition which are effective even in various atmospheres. It is in.

[0006]

That is, the gist of the present invention is as follows.
One or two selected from salicylic acid and its salts, 5-sulfosalicylic acid and its salts, anthranilic acid and its salts
The present invention relates to a stabilized acrylamide polymer stabilizer comprising at least one or more kinds, and further to a stabilized polymer composition obtained by blending the stabilizer with an acrylamide polymer.

[0007] The carboxylic acid group in the stabilizer of the present invention may be a free acid or a salt. Salts include sodium salts, potassium salts, ammonium salts,
Alternatively, organic ammonium salts such as trimethylammonium salt and triethylammonium salt can be further exemplified, but the present invention is not particularly limited thereto. The amino group contained in anthranilic acid may be a free amino group, and may be a hydrochloride, a nitrate, a carbonate, a sulfate, a phosphate,
It may be a salt such as an organic acid salt.

In the present invention, the acrylamide polymer may be an acrylamide homopolymer,
A copolymer in which acrylamide occupies the largest ratio may be used. Examples of the monomer which is a component other than acrylamide of the copolymer include methacrylamide, acrylic acid, methacrylic acid, or salts thereof, dialkylaminoalkyl esters and salts thereof and quaternary ammonium salts, vinylpyridine, allylamine or these. Salts, vinyl sulfonic acid, acrylamidoalkylsulfonic acid such as 2-acrylamido-2-methylpropanesulfonic acid and salts thereof, N-vinylpyrrolidone, acrylonitrile, methacrylonitrile, lower alkyl esters of acrylic acid or methacrylic acid, and the like. be able to.

In addition, those which do not rely on a so-called copolymerization reaction or those in which a part of the amide group of the acrylamide polymer is hydrolyzed, or other functional groups are introduced by a polymer reaction such as methylolation or Mannich reaction, A mixture of an acrylamide homopolymer or copolymer and another water-soluble polymer may be used as long as the ratio of the acrylamide component is the maximum.

The amount of the stabilizer of the present invention to be added to the acrylamide polymer is not particularly limited, and may be appropriately adjusted depending on the degree of the atmosphere to which the acrylamide polymer is exposed. It is preferable to add 0.01 to 20% by weight. That is, in order to sufficiently exhibit the stabilizing effect, the content is preferably 0.01% by weight or more, and even if it exceeds 20% by weight, the effect is not so much improved by the addition. The stabilizer of the present invention exerts a sufficient effect when used alone or as a mixture of two or more thereof. However, if there is no adverse effect due to the addition of a known stabilizer, the stabilizer is used in combination. You can also.

In obtaining a stabilized polymer composition in which the stabilizer of the present invention is blended with an acrylamide polymer, the stabilizer may be added to a monomer before polymerization of the acrylamide polymer or an aqueous solution thereof. A powdery stabilizer or an aqueous stabilizer solution may be mixed with the gel polymer obtained by the above method. Further, it may be added to the aqueous polymer solution.

The method for producing the acrylamide polymer used in the present invention is not particularly limited, but is usually
Aqueous solution polymerization using a radical polymerization initiator.
0% by weight, preferably 5 to 30% by weight of an aqueous solution of a monomer mainly composed of acrylamide is added to a peroxide such as a persulfate, hydrogen peroxide, an organic peroxide, or a tertiary amine, a sulfite or A redox initiator combined with a reducing agent such as a ferrous salt, or azobisisobutyronitrile, 2,2′-azobis- (2-amidinopropane) dihydrochloride,
An azo initiator such as 4,4'-azobis- (4-cyanovaleric acid) is added in an amount of about 0.0001 to 0.4% by weight based on the monomer, and -10 to 100%.
Polymerize at ° C.

When the stabilizer of the present invention is added before polymerization, it is effective in preventing the formation of insolubles due to thermal deterioration of the polymer even when the temperature rises during polymerization. Also, after polymerization, pulverization,
In many cases, the polymer is dried into a powdery polymer, and hot air drying is often used for this drying.However, if a stabilizer is added to the polymer before this drying, the molecular weight due to thermal degradation of the polymer is increased. And the formation of insoluble components can be prevented.

The aqueous solution of the stabilized acrylamide polymer composition of the present invention exhibits excellent stability even at a temperature lower than room temperature such as 0 ° C. or at a high temperature such as 80 ° C. or 120 ° C. Since the aqueous solution of the polymer composition to which no is added or stabilized by the conventional stabilizer is particularly deteriorated at a high temperature, the polymer composition of the present invention is particularly useful for the stabilizing effect at a high temperature. .

[0015] The acrylamide polymer is used for each purpose.
It is often used as an aqueous solution by mixing with water at the site of use, but there is no particular limitation on the type of water to be used as the aqueous solution, and any of seawater, river water, groundwater, city water, and industrial water is used. be able to.

[0016]

The present invention will be described in more detail with reference to the following examples. Parts in the examples are parts by weight unless otherwise specified. Example 1 140 ppm of sodium chloride and calcium chloride in ion-exchanged water
160 ppm was dissolved. [Η] = 19, hydrolysis degree
0.05% by weight of 16 mol% of polyacrylamide was added and dissolved by stirring. To the polymer solution thus obtained, a 0.1% aqueous solution of salicylic acid adjusted to pH 7 with sodium hydroxide was added so that the salicylic acid content was 1% by weight based on the polymer, and the mixture was stirred and dissolved until it became uniform. After measuring the viscosity of this solution at 25 ° C. with a B-type viscometer, it was placed in a thermostat adjusted to 70 ° C. After one week, take out of the thermostat, viscosity (25 ° C)
Was measured, and the viscosity retention was determined by the following equation. Viscosity retention (%) = solution viscosity after holding in a thermostat for a predetermined time /
Solution viscosity immediately after dissolution × 100 The results are shown in Table 1.

Examples 2 to 8 and Comparative Examples 1 to 4 Instead of salicylic acid, the compounds shown in Table 1 were adjusted to pH 7 with an alkali shown in Table 1 and added in the amounts shown in Table 1 (Example 2). The same procedures as in Example 1 were performed except for Comparative Examples 2 to 8). In Comparative Examples 1 and 3, pH was replaced with salicylic acid.
The procedure was the same as in Example 1 except that a 0.1% aqueous solution of the compound shown in Table 1 was added without adjustment, and that in Comparative Example 4 salicylic acid was not added. The results are shown in Table 1 together with the results of Example 1.

[0018]

[Table 1]

Example 9 150 ppm of calcium chloride, 70 ppm of magnesium chloride, 380 ppm of sodium hydrogen carbonate, 20 p of sodium carbonate were added to ion-exchanged water.
pm was dissolved. Using this solution, the temperature of the thermostat was set to 120
The viscosity retention was determined in the same manner as in Example 1 except that the temperature and the retention time were changed to 3 hours. Table 2 shows the results.

Examples 10 to 12 and Comparative Examples 5 to 7 Instead of salicylic acid, a 0.1% aqueous solution of the compound shown in Table 2 was adjusted to pH 7 with an alkali shown in Table 2 in an amount shown in Table 2 per polymer. The procedure was the same as in Example 9 except for the addition. However, in Comparative Example 7, the pH was not adjusted. The results are shown in Table 2 together with the results of Example 9.

[0021]

[Table 2]

Example 13 20 parts of acrylamide, 5 parts of acrylic acid, ion-exchanged water 75
0.25 parts of salicylic acid was added to the aqueous monomer solution consisting of 1 part, sodium hydroxide was added to adjust the pH to 7, the system was replaced with nitrogen, and then potassium persulfate 0.002 part at 15 ° C, sodium bisulfite
0.002 parts and 0.05 parts of azobisamidinopropane hydrochloride were added and polymerized. The obtained hydrous polymer gel was crushed into granules having a diameter of about 5 mm, dried with a hot air drier at 60 ° C., dried, and ground to about 2 mm or less to obtain a water-soluble polymer. This powder was dissolved in an aqueous solution containing 140 ppm of sodium chloride and 160 ppm of calcium chloride to obtain a 0.05% aqueous polymer solution. After measuring the viscosity of this solution in the same manner as in Example 1, the solution was placed in a thermostat adjusted to 70 ° C. One week later, it was taken out of the thermostat, the viscosity was measured, and the viscosity retention was determined. Table 3 shows the results.

Example 14, Comparative Example 8 Polymers were obtained in the same manner as in Example 13 except that anthranilic acid was used instead of salicylic acid, and the viscosity retention of these polymer aqueous solutions was determined in the same manner as in Example 13. Examined. Table 3 shows the results. A polymer was obtained in the same manner as in Example 13 except that salicylic acid was not used, and the viscosity retention was examined. Table 3 shows the results.

[0024]

[Table 3]

[0025]

As described above, by using the stabilizer of the present invention, it is possible to prevent thermal deterioration of the acrylamide polymer in various environments. Further, the acrylamide-based polymer composition containing the stabilizer of the present invention is stable in a wide temperature range from room temperature to a high temperature of 100 ° C. or higher. The acrylamide-based polymer of the present invention is particularly useful for, for example, petroleum recovery agents, thickening agents for drilling mud, and the like, which are likely to be used at high temperatures for maintaining long-term performance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-114659 (JP, A) JP-A-54-83048 (JP, A) JP-A-61-44942 (JP, A) JP-A-61-44942 136545 (JP, A) JP-A-62-277407 (JP, A) JP-B-49-27660 (JP, B1) JP-B-49-27661 (JP, B1) JP-B-49-27662 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 33/26 C08K 5/13 C08K 5/18 C08K 5/42 CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] An acrylamide polymer stabilizer comprising one or more selected from salicylic acid and its salts, 5-sulfosalicylic acid and its salts, and anthranilic acid and its salts. 2. A stabilized polymer composition comprising the stabilizer according to claim 1 and an acrylamide polymer. 3. The stabilized polymer composition according to claim 2, wherein the amount of the stabilizer according to claim 1 is 0.01 to 20% by weight based on the acrylamide polymer.