JPS60177010A - Preparation of polyacrylamide - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having improved viscosity and flocculating properties in high productivity, by polymerizing an aqueous solution of acrylamide having a specific concentration in the presence of an azo polymerization catalyst, NaHSO3 or Na2SO3, and a copper salt. CONSTITUTION:(A) 100-2,000ppm azo polymerization catalyst [e.g., 2,2'-azobis (2-amidinopropane)hydrochloride, etc.], (B) 3-200ppm NaHSO3 or Na2SO3, and (C) 0.1-10ppm calculated as metal of a copper salt (CuSO4, etc.) based on acrylamide preferably in the order of the component C, the component A, and the component C are added to 10-35wt% aqueous solution of acrylamide, polymerization is carried out in a nitrogen atmosphere, the prepared gel material is granulated into preferably 2-5mm. average particle diameter, and dried to <=10wt%, to give the desired polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyacrylamide.

Of polyacrylamide! ! ! As a production method, for example, a method of polymerizing in the presence of an azo polymerization catalyst such as an aqueous acrylamide solution is known. Polymerization of acrylamide is an exothermic reaction, and if the polymerization temperature is too high, the performance of the resulting polymer will deteriorate. Therefore, a method of lowering the monomer concentration during polymerization can be considered, but when the monomer concentration is low, there is a drawback that it takes time and effort to dry the polymer after one polymerization. Another option is to lower the temperature at which one polymerization starts, but when an azo polymerization catalyst is used, polymerization does not proceed smoothly at too low a temperature, so the polymerization rate is particularly slow in the early stage of polymerization, and therefore one polymerization time is It has the disadvantage that it is long and has poor productivity, and furthermore, the performance of the obtained polymer is also low.

In view of the above-mentioned circumstances, the present inventors have discovered that even when polymerizing an aqueous acrylamide solution, the monomer concentration is relatively high and the temperature at which polymerization starts is low, a good force polymerization reaction can be carried out with a short polymerization time. , the polymerization method f! had inferior performance of the resulting polymer. :Results of various studies aimed at obtaining results.

The inventors have discovered that this object can be achieved by polymerizing in the coexistence of an azo polymerization catalyst and a specific compound, and have completed the present invention.

That is, 1) The gist of the present invention is that in polymerizing 19 to 33% by weight of acrylamide aqueous W'Y, 100 to . 2 o o o o p
pm of azo polymerization catalyst, ■ 3 to 200 ppm of acidic sodium sulfite or sodium sulfite and metal as Q, / -/
A method for producing polyacrylamide characterized by the presence of a copper salt of OppI.

The present invention will be explained in detail below.

The method for producing polyacrylamide, which is the object of the present invention, is a method of polymerizing an aqueous solution of acrylamide monomer, and the monomer concentration is /θ~35, preferably 2θ~
It weighs 30 pounds. If the monomer concentration is too high, high temperatures will occur during polymerization and the quality of the resulting polymer will deteriorate;
If it is too low, it is not preferable because the polymer will be difficult to dry.

In the present invention, together with a known azo polymerization catalyst as a catalyst,
It is an essential requirement to use acidic sodium sulfite or sodium sulfite in combination with a copper salt. When an azo polymerization catalyst is used alone, even if the monomer concentration is increased and the polymerization initiation temperature is lowered, the polymerization rate is slow and good polymerization cannot be carried out. Copper salt is generally well known as a polymerization inhibitor for acrylamide, and it is thought that it is necessary to completely remove it during one polymerization, but in the case of the specific polymerization system assumed in this invention, On the contrary, a specific amount of copper salt improves the polymerization rate.

Examples of azo polymerization catalysts include 1. J-Azobis C
Co-amidinoprobano hydrochloride, azobisisobutyronitrile, 2,2'-azobis(goomethoxyco, goodimethylvaleronitrile).

1, //-Azobis(cyclohexanecarbonitrile) and the like are preferred, and co-,2'-azobis(coamidinopropanph hydrochloride) is particularly preferred.

The amount of this azo compound added is t00~
200099m, preferably qoo~/lIo o
ppm, and if the amount added is too small, polymerization will not be carried out well, and if it is too large, the molecular weight of the resulting polymer will decrease, which is not preferable.

On the other hand, the amount of acidic sulfite or sodium sulfite added is 3~00 ppm, preferably S~
/ 00 pPm, and if this amount is too small, polymerization will not be carried out well.

Furthermore, if the amount is too large, the performance of the resulting polymer will deteriorate, which is not preferable.

Copper salts typically include water-soluble covalent copper salts such as cupric sulfate, cupric chloride, cupric bromide, cupric acetate, cupric oxalate, and cupric nitrate. Among them, cupric sulfate is commonly used. The amount of copper salt to be used is O, iA-coo ppm as a metal, preferably Oo-2 ppm, and if this amount is too small, the polymerization rate will be slow, so it will take a short time. On the other hand, if the amount is too large, monopolymerization will be inhibited and the polymerization will not proceed, which is not preferable.

In the present invention, the order of adding the above-mentioned additives into the polymerization system is usually such that acidic sodium sulfite or sodium sulfite is preferably added last.

Copper salt, azo polymerization catalyst 1, and then 7111 g of acidic sodium sulfite or sodium sulfite were added in that order.

The polymerization temperature in the present invention is usually -1o-io.

The temperature at which one polymerization starts is, for example, -0C or lower, preferably ioC or lower. In the present invention, even if the polymerization initiation temperature is set at a low temperature, one polymerization proceeds satisfactorily.The polymerization time is usually about 0.5 to 10 hours.

To carry out the present invention, for example, a monomer aqueous solution is charged in a closed polymerization tank, nitrogen gas is blown into the aqueous solution to remove dissolved oxygen, and then the catalyst of the present invention is added as an aqueous solution and polymerization is carried out. After the polymerization is completed, the polymer is a gel-like substance, and the average particle size is determined by a conventional method.
The granules are granulated to Q%, preferably co-s%, and the granules are further dried to a water content of 19% by weight or less.

According to the present invention, even if the degree of polymerization initiation source is lowered by 1, for example, 1 during the direct polymerization of acrylamide, the polymerization can be carried out smoothly in a short period of time, resulting in extremely high productivity. Furthermore, the obtained polymer has excellent viscosity and aggregation performance, and is industrially advantageous.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1-G and Comparative Examples I to J Acrylic acid 3wt% water soluble 711/31 to 73
) was charged into a closed type polymerization type 1 carbonate. After blowing nitrogen gas o, 2i into the aqueous solution to completely degas it.

First, add the copper salt additives shown in Table 1 at a liquid temperature of 10°C,
Next, U,-'-azobis(coamidinoprobanohydrochloride j-00pl)m and the acidic sodium sulfite shown in Table 1 were sequentially added and mixed and allowed to stand for polymerization.

After the polymerization, the gel-like polymer was granulated using an extrusion granulator to have an average particle size of about 100 ml, and then the granulated material was dried with hot air at gθ°C for 3 hours.

The viscosity and aggregation performance of the granular polymer thus obtained were measured, and the polymerization rate was determined by measuring the temperature change within a 1 degree doubling, and the results shown in Table 1 were obtained.

Example 3 and Comparative Example In place of 1 g of sodium sulfite in Example 1,
・・・・・・・・・・・・△1% diameter or less・・・・・・・・・
・・・・・・・・・×Applicant Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - (1 other person)

Claims (7)

[Claims] (1) When polymerizing an acrylamide aqueous solution with a weight ratio of 77 to 33, for the acrylamide monomer,
■/ o o ~ J o o o ppm of azo yarn polymerization catalyst, ■ 3 ~ coo o ppm of acidic sodium sulfite or sodium sulfite, and ■ metal as 0, i −/ Oppm.
A method for producing polyacrylamide, characterized by the presence of a copper salt. (2) Is the copper salt water-soluble 2111ti copper salt? : A method according to the first aspect of the claim. (3) The method according to claim 7, wherein the copper salt is cupric sulfate. (4) The method described in claim No. 1, characterized in that the copper salt is added to the polymerization system before acidic sodium sulfite or sodium sulfite. (5) The method according to claim 1, characterized in that the amount of copper salt used is Q, 2 to 299 m as metal, relative to the acrylamide monomer. (6) The method according to claim 7, wherein the azo polymerization catalyst is co,2'-azobis(-monamidinopropanohydrochloride). (7) The method according to claim 1, characterized in that the polymerization initiation temperature is 20° C. or lower.