JPS61118410A - Production of acrylamide polymer of low viscosity - Google Patents

Abstract

PURPOSE:The polymerization is carried out, as the concentration of the starting monomers is controlled within a specific range and the polymerization system is kept in a boiling state to form a water-containing polymer which is readily particulated and easy to be handled whereby the title polymer is obtained in high particulating efficiency. CONSTITUTION:At first, the concentration of monomers including acrylamide is controlled within a range from 30-50wt% and as the water in the polymerization system is allowed to boil with the action of the polymerization heat of the monomers and to remove more than 10%, preferably 20-50% of the polymerization heat as the latent heat of evaporation, the polymerization is carried out. The resultant water-containing polymer is particulated by a known method, dried to give the objective polymer. The use of a combination -of 2,2'-azobis-2- amidinopropane hydrochloride with 4,4'-azobis-(4-cyanovaleric acid at a weight ratio of 20/80-50/50 is preferable from the view points of operation safety.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a low-viscosity acrylamide-based polymer. It is related to the manufacturing method.

[Conventional technology]

Acrylamide-based polymers are usually produced by polymerizing an aqueous solution of 7-mer in the presence of a catalyst to obtain a gel-like water-containing polymer, which is then pulverized and dried, which is then further treated with formalin. Mannich-modified polymers obtained by treatment with dimethylamine and dimethylamine, or Hofmann-decomposed polymers obtained by treatment with sodium hypochlorite and caustic soda, are useful as flocculants in certain fields. In order to produce this Mannich-formed polymer or phosphatide-decomposed polymer, it is necessary to react the raw material acrylamide-based polymer in an aqueous solution. In general, polymers with high molecular weight and high viscosity are desirable, so when using commonly obtained polymers as raw materials,
For example, it is difficult to prepare a uniform aqueous solution even at a concentration of %/%. Therefore, in the case of an acrylamide polymer used as a raw material for a Mannich polymer or a Hofmann-decomposed polymer, a low-viscosity polymer having an intrinsic viscosity [η] of about 3 to 70 (about 10,000 to 2,000,000 molecules) is usually desirable. This can be achieved by conventional methods by adjusting the amount of catalyst used, and it is possible to obtain a low viscosity polymer by using a relatively large amount of catalyst.

[Problem that the invention seeks to solve]

However, when producing low-viscosity polymers using conventional methods, although the viscosity can be easily adjusted, the gel-like water-containing polymer obtained is weak and highly sticky, so it is necessary to make the water-containing polymer into fine particles. It was difficult to do so. for example,
When a hydrous polymer is pulverized using a meat grinder type extrusion granulator, the hydrous polymer sticks strongly to the inside of the equipment, and the extrusion screw runs out, causing the hydrated polymer to accumulate inside the equipment.
As a result, the granulation efficiency was poor, and in some cases, granulation itself was not possible.

[Means for solving problems]

In view of the above-mentioned circumstances, the present inventors have conducted various studies on methods for obtaining a water-containing polymer that is easily made into fine particles and has good handling properties when producing a low-viscosity acrylamide-based polymer.
The present invention was completed based on the discovery that the object of the present invention can be achieved by controlling the monomer concentration and conducting the polymerization in a boiling state in the polymerization system.

That is, the gist of the present invention is to provide a method for producing a low-viscosity acrylamide-based polymer by polymerizing an acrylamide-containing upper polymer, with a monomer concentration of 30~! , 0% by weight, and the water in the polymerization system is boiled to reduce the heat of polymerization to 10%.
The present invention relates to a method for producing a low-viscosity acrylamide polymer, which is characterized by removing the above as latent heat of vaporization.

The acrylamide-containing monomer targeted by the present invention usually includes acrylamide alone or a mixture of acrylamide and a monomer copolymerizable therewith.

Examples of heptamers that can be copolymerized with acrylamide include acrylic acid, sodium acrylate, sodium co-acrylamide methylpropanesulfonate, diethylaminoethyl methacrylate and its φ-class salts, diethylamine ethyl acrylate and its φ-class salts, and other known compounds. Monomers are mentioned, and in case of copolymerization, the content of acrylamide in the monomer mixture is! 0 molt or more, preferably 70-f
: Multi or higher is appropriate.

In the present invention, a low viscosity polymer having an intrinsic viscosity [η] of 3 to 10 is produced by polymerizing the above monomer aqueous solution in the presence of a catalyst, and the concentration of the monomer aqueous solution is 30 to 10% by weight. Moreover, it is an essential requirement to boil the water in the polymerization system and remove 10% or more of the polymerization heat, preferably 20 to SO%, as the latent heat of vaporization of the water. In the present invention, after the polymerization has started, the polymerization system is not actively heated or cooled, but is carried out by relying on the heat generated by the polymerization heat of acrylamide to bring the water in the system to a boiling state, and the latent heat of the water that evaporates at this time. The temperature within the system is controlled only by If the monomer concentration is lower than the above range, the properties of the obtained water-containing polymer will be poor and it will not be possible to make the particles fine. This is not preferable because it becomes impossible to refine the particles in the machine.

The catalyst that can be applied in the present invention is not particularly limited, but since the polymerization in the present invention proceeds at a relatively high temperature, the temperature at which the half-life indicates the io waiting time is usually j (preferably a catalyst of 7°C or higher). , for example, 2, λ'-7zobis-4-amidinopropane hydrochloride, φ, Hiro'-azobis-(4C-cyanowalleriaciic acid), λ, 1'-azobis-(2,II-dimethylpaleronitolyl), azobisisobutyronitrile, --cyanocopropylazoformamide)",
/, /'-azobis-(cyclohexene-7-carbonitrile), and the like.

The amount of these catalysts used varies depending on the polymerization conditions, etc., but since the purpose of the present invention is to obtain a low viscosity polymer, it is usually 100 to 7000% of the monomer.
It is selected from a relatively large amount range such as ppm.

In addition, in the method of the present invention, the inside of the polymerization system reaches a boiling state, so it is better to avoid rapid boiling from the viewpoint of operational safety. Particular preference is given to using a mixture of 20~jO heavy acid and ≠μ'-azobis-(μm cyanowalleric acid) to so-o heavy acid.

In the present invention, a seven-mer aqueous solution is usually placed in a polymerization tank having an exit port for steam generated by boiling in the upper part, for example, from -j°C to
After preparing at a temperature of JO℃ and degassing it with nitrogen gas,
This is carried out by adding a predetermined amount of an aqueous catalyst solution. Usually, the inside of the system reaches a boiling state about 20 minutes after the start of polymerization, and this state continues for about /-10 minutes. Polymerization time is typically about 1 to 3 hours total. The amount of water that evaporates at this time is usually 2 to 30% by weight of the water in the polymerization system, so
The resulting water-containing polymer also has a low water content.

The water-containing polymer obtained by polymerization is recovered as a finely divided acrylamide polymer by pulverization and drying according to a known method. The granulation is usually carried out using a granulator such as a meat grinder type extrusion granulator, and the granulation is carried out using a granulator such as a meat grinder type extrusion granulator, and the granulation is carried out using a granulator such as a meat grinder type extrusion granulator. Granulate into R granules. Also,
Drying is usually done using a rotary dryer or band dryer.
The process is carried out at a temperature of 0 to 0°C, preferably AO, / / 0°C, until the water content becomes 111751% or less, preferably io type weight or less.

〔Effect of the invention〕

Hereinafter, according to the present invention, when producing a low-viscosity acrylamide-based polymer with an intrinsic viscosity [η] of 3 to io,
The properties of the gel-like water-containing polymer obtained by polymerization are very good, and therefore the water-containing polymer can be easily pulverized.

Furthermore, since the resulting water-containing polymer has a low water content, it also has the effect of simplifying the subsequent drying process. Furthermore, in the present invention, since the inside of the polymerization system is brought to a boiling state, there is no need to control the maximum temperature during polymerization, which simplifies the management of the polymerization operation, and because the maximum temperature is always constant, it is possible to maintain constant quality. Polymers can be produced and their industrial value is enormous.

〔Example〕

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

Note that the intrinsic viscosity [η] indicates the viscosity of the polymer in normal saline at a temperature of 30°C.

Example: 1100 ml of a 37.5 weight aqueous thiacrylamide solution adjusted to pH 4 was charged into a polymerization tank whose surface was lined with tetrafluoroethylene resin, and then degassed with nitrogen gas. j 00 for monomers at a temperature of °C
2.ppm. λ'-Azobis-2-amidinopropane hydrochloride and an aqueous monomer solution were added and polymerization was carried out for about 3 hours.

When the temperature rise in the system was investigated during this polymerization, the internal temperature began to rise 5 minutes after the addition of the catalyst and reached a boiling state 6j minutes later. The boiling state was mild and the boiling level was about 6 minutes. Also, the heat of polymerization removed by the latent heat of vaporization of water during this polymerization is! , I A kcal, and the total heat of polymerization is 37.7
%Met. As a result, the water content of the water-containing polymer obtained by polymerization was approximately 4 cO1≠H.

The water-containing polymer after polymerization is then taken out from the polymerization tank,
After granulating the product into granules with an average particle size of ~3 ml using a meat grinder type extrusion granulator, the mixture was dried with hot air at 10° C. for 2 hours to obtain a fine granular polymer having a water content of IAqb.

The intrinsic viscosity of the fine particulate polymer thus obtained was 7.4c (molecular weight approximately 3 million), and the solubility in water was good, with no insoluble matter observed.

Furthermore, in the granulation process in the granulator, the water-containing polymer did not stick to the inside of the apparatus, and the extrusion screw did not run empty, making it possible to efficiently obtain the target granules.

EXAMPLE In the method of Example 1, 2.000 ppm/000 ppm of chloride as a catalyst was used. When polymerization was carried out in the same manner as in Example 1 using λ'-azobis-λ-amidinopropane hydrochloride, the internal temperature began to rise 10 minutes after the addition of the catalyst and reached a boiling state after 10 minutes. The boiling state was intense and the temperature was about 1 minute.

At this time, the heat of polymerization removed by the latent heat of vaporization of water was the same as in Example 1.

Next, the hydrous polymer after polymerization was treated in the same manner as in Example 1, and the intrinsic viscosity of the resulting fine particulate polymer was 7.0 (molecular weight approximately 3 million), and the solubility in water was also low. It's good. Furthermore, the granulation operation was carried out smoothly, and the target granules were obtained efficiently.

Comparative Example In the method of Example 1, the concentration of the acrylamide aqueous solution was 2! When polymerization was carried out in the same manner in terms of weight %, the internal temperature began to rise 4 CO minutes after the addition of the catalyst, and only a slight boiling was observed 60 minutes later, with almost no water evaporating.

Next, the water-containing polymer after one polymerization was treated in the same way.
Although the intrinsic viscosity [η] of the obtained fine-grained polymer was O, the tackiness of the water-containing polymer in the granulator was extremely high, which placed a large load on the granulator and made it impossible to granulate efficiently. There wasn't.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (3)

[Claims] (1) In a method for producing a low-viscosity acrylamide-based polymer by polymerizing an acrylamide-containing monomer, the monomer concentration is 30 to 50% by weight, and water in the polymerization system is boiled to evaporate 10% or more of the polymerization heat. A method for producing low-viscosity acrylamide polymers, which is characterized by removing latent heat. (2) During polymerization, 2,2'-azobis-
2-amidinopropane hydrochloride and 4,4'-azobis-(
The method according to claim 1, characterized in that 4-cyanourelian acid) is used. (3) Intrinsic viscosity of the acrylamide polymer produced [
The method according to claim 1, characterized in that η] is 3 to 10.