CN102199250A - Method for preparing anionic polyacrylamide microspheres - Google Patents

Abstract

A method for preparing anionic polyacrylamide microspheres, which is prepared by a reverse-phase suspension polymerization method, the main steps of which are: a) dissolving a dispersant in a dispersed phase; b) adding an alkali solution to an acrylamide monomer solution, Make a neutral monomer solution; c) Heat the monomer solution to 45-60°C under a nitrogen atmosphere, add an initiator, and react at 60-65°C; d) Vacuum degree 0.01MPa-0.05MPa, temperature 50-65°C Carry out azeotropic water removal under the following conditions to obtain the target product; in the above steps, the weight ratio of dispersed phase: dispersant: monomer solution: initiator is 70-95: 0.4-2: 5-30: 0.0001-0.001. The product of the present invention is white or colorless and transparent solid microspheres. Compared with emulsion and solution products, the active ingredient is higher, the properties are more stable, it is more convenient for long-term storage and long-distance transportation, and it is easy to quantitatively configure the required solution on site. .

Description

A method for preparing anionic polyacrylamide microspheres

technical field

The invention relates to a preparation method of anionic polyacrylamide, more specifically to a preparation method of water-soluble anionic polyacrylamide microspheres prepared by reverse phase suspension polymerization.

Background technique

Polyacrylamide (PAM) is a linear water-soluble polymer. Due to the large chemical reaction of its side chain phthaloamide group, it can undergo conversion reactions with various compounds. Therefore, polyacrylamide and its derivatives can be used As a flocculant, thickener, antistatic agent, surfactant, etc. It is widely used in petroleum exploration, water treatment, papermaking, mining, metallurgy, geology, textile, construction, medicine, sugar refining, breeding, agriculture and other industrial sectors. It is known as "all kinds of additives".

The main forms of polyacrylamide (PAM) products are aqueous colloid, powder and latex, and there are anionic, cationic and nonionic types. Among the organic polymer flocculants, anionic polyacrylamide has the longest development history and the most widely used, so it has attracted the most attention. Its advantages are: the cost is far lower than cationic organic polymer flocculants and amphoteric organic polymer flocculants; the flocculation effect is good and the process is mature. In addition, because the active phthalamide groups and carboxylic acid groups on the polymer chain can physically and chemically react with various substances, it has excellent surface activity in addition to the properties of the polymer chain, and is widely used Used in papermaking, mineral processing, oil extraction, metallurgy, building materials, food processing, water treatment and other industries.

Inverse suspension polymerization is an ideal method for industrial production of water-soluble polymers developed in the past ten years. It is a polymerization reaction in which the aqueous monomer solution is suspended in an organic solvent in the form of small droplets. Inverse suspension polymerization technology was applied to the polymerization of homogeneous monomer solutions such as vinyl chloride and acrylonitrile as early as the 1960s. This polymerization method removes the heat of polymerization by refluxing volatile organic liquids. In order to maintain a low polymerization temperature And there is no cross-linking component in the polymer, and the oxidation-reduction initiation system is often used for polymerization. The research on the inverse suspension polymerization of anionic polyacrylamide mainly focuses on the production of superabsorbent resin. At present, some large foreign companies have realized industrialization, and there are some laboratory research reports in China, but there is no such product in China. .

Contents of the invention

The purpose of the present invention is to provide a method for preparing anionic polyacrylamide microspheres.

In order to achieve the above object, the method for preparing anionic polyacrylamide microspheres provided by the present invention is prepared by reverse-phase suspension polymerization, and its main steps are:

a) dissolving the dispersant in the dispersed phase;

b) adding an alkali solution to the monomer solution of acrylamide to make a neutral monomer solution;

c) heating the monomer solution to 45-60°C under a nitrogen atmosphere, adding an initiator, and reacting at 60-65°C;

d) Azeotropic water removal is carried out at a vacuum degree of 0.01MPa-0.05MPa and a temperature of 50-65°C to obtain the target product;

In the above steps, the weight ratio of dispersed phase: dispersant: monomer solution: initiator is 70-95: 0.4-2: 5-30: 0.0001-0.001.

Described preparation method, wherein, dispersant is sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, poly Oxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene hydrogenated castor oil, soybean lecithin, ten Octyl phosphoester, polyoxyethylene nonylphenol ether, sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, octadecyltrimethylammonium bromide or dihexadecyltrimethylbromide ammonium chloride; the dispersed phase is cyclohexane; the initiator is ammonium persulfate, potassium persulfate or sodium persulfate.

In the preparation method, one or more of acrylic acid, methacrylic acid, and 2-acrylamido-2-methylpropanesulfonic acid is added in a weight ratio of 10-40 in step b.

The product obtained by this method is white or colorless transparent solid microspheres. Compared with emulsion and solution products, the active ingredient is higher, the properties are more stable, it is more convenient for long-term storage and long-distance transportation, and it is easy to quantitatively configure on-site as required. solution. Compared with the ground and broken solid products, it has the advantages of beautiful appearance, smooth beads, low investment in dehydration equipment and less energy consumption for dehydration. The anionic polyacrylamide microspheres of the present invention also have the advantages of high molecular weight, fast dissolution speed and the like.

Description of drawings

Fig. 1 is a micrograph of anionic polyacrylamide synthesized in Example 1 of the present invention.

Fig. 2 is a photomicrograph of anionic polyacrylamide synthesized in Example 2 of the present invention.

Fig. 3 is a microscope photo of anionic polyacrylamide synthesized in Example 3 of the present invention.

Fig. 4 is a photomicrograph of anionic polyacrylamide synthesized in Example 4 of the present invention.

Fig. 5 is a gel permeation chromatography (GPC) elution curve of the anionic polyacrylamide synthesized in Example 1 of the present invention.

Fig. 6 is a gel permeation chromatography (GPC) elution curve of the anionic polyacrylamide synthesized in Example 2 of the present invention.

Fig. 7 is a gel permeation chromatography (GPC) elution curve of the anionic polyacrylamide synthesized in Example 3 of the present invention.

Fig. 8 is a gel permeation chromatography (GPC) elution curve of the anionic polyacrylamide synthesized in Example 4 of the present invention.

Detailed ways

Example 1-4

According to the data of table 1, in the 250mL four-neck flask, add 150mL of dispersed phase cyclohexane and dispersant (dispersant can be selected sorbitan monostearate, sorbitan monooleate, sorbitan Trioleate, sorbitan tristearate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate Ester, polyoxyethylene hydrogenated castor oil ester, soybean lecithin, stearyl phosphate, polyoxyethylene nonylphenol ether, sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, octadecyl Trimethylammonium bromide or dihexadecyltrimethylammonium bromide), heated to 50°C and stirred to dissolve the dispersant, then cooled for later use.

Add NaOH into the beaker to neutralize the protons in the monomer solution of acrylamide, dissolve it with a small amount of distilled water, and cool it at room temperature for use. And dissolve completely with a small amount of distilled water. Put the monomer solution in an ice-water bath, slowly add NaOH solution dropwise to it, and stir to make it evenly mixed. Slowly drop the prepared monomer solution into the four-neck flask, pass nitrogen gas for about 30 minutes, and then start to heat up. When the temperature rises to 55°C, add quantitative ammonium persulfate solution. After a while, the reaction self-heated. After the end of the temperature rise, the temperature was controlled between 60-65° C. to continue the reaction for one hour. After the reaction is completed, start azeotropic water removal, turn on the circulating water vacuum pump, control the vacuum to maintain the temperature of the reaction system between 50-65°C, and start the reflux condensation operation. The lower layer of the condensate is water. When the effluent reaches more than 75% of the total amount of water added (it takes about 5 hours to complete), the heating can be stopped, and after cooling, the reaction product is suction-filtered to obtain colorless transparent polymer microspheres. The polymer microspheres were placed in a vacuum oven and dried in vacuum.

Table 1: The raw material formula of embodiment 1-4

Claims (3)

1. a method for preparing the anion-polyacrylamide microballoon adopts the preparation of inverse suspension polymerization method, and its key step is:

A) dispersion agent is dissolved in disperse phase;

B) in the monomer solution of acrylamide, add alkaline solution, make neutral monomer solution;

C) the heating monomer solution reacts in 60-65 ℃ to 45-60 ℃ of adding initiator under nitrogen atmosphere;

D) vacuum tightness 0.01MPa-0.05MPa carries out azeotropic water removing under temperature 50-65 ℃, obtains target product;

In the above-mentioned steps, disperse phase: dispersion agent: monomer solution: the weight part ratio of initiator is 70-95: 0.4-2: 5-30: 0.0001-0.001.

2. preparation method according to claim 1, wherein, dispersion agent is a sorbitan monostearate, anhydrous sorbitol list olein, Witconol AL 69-66, the anhydrous sorbitol tristearate, polyoxyethylene 20 sorbitan monostearate, polyoxyethylene 20 sorbitan monooleate, polyoxyethylene 20 sorbitan trioleate, the polyoxyethylene hydrogenated castor oil ester, soybean lecithin, octadecanol phosphoric ester, polyoxyethylene nonylphenol ether, sodium laurylsulfonate, Sodium dodecylbenzene sulfonate, octadecyl trimethylammonium bromide or double hexadecyl trimethylammonium bromide;

Disperse phase is a hexanaphthene;

Initiator is ammonium persulphate, Potassium Persulphate or Sodium Persulfate.

3. preparation method according to claim 1 adds among the step b that weight part ratio is arranged is in the vinylformic acid, methacrylic acid, 2-acrylamido-2-methyl propane sulfonic acid of 10-40 one or more.

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