JPH0141658B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a water-soluble acrylamide-based high polymer composition that has good solubility in water and is low in dust. Water-soluble acrylamide-based high polymers (hereinafter referred to as polymers) are widely used as flocculants, thickeners, sticky agents for paper manufacturing, and the like. Many of these polymers are manufactured and supplied in powder form. Since most of these polymers are used after being made into a low concentration aqueous solution of about 0.01 to 0.5%, it is necessary to dissolve them in water. When dissolving polymer powder in water, a method is used in which the powder is added little by little while stirring the water.For this purpose, an operator must directly perform the addition operation, or a special supply for the addition must be used. equipment is required. Despite this, so-called "mamako" tends to occur, and it is often seen that a very long time is required for dissolution. Furthermore, there are many cases in which the polymer powder absorbs moisture, resulting in a decrease in powder fluidity, or is classified, forming bridges inside the powder supply device, which impede stable supply. Furthermore, since the polymer powder contains fine particles, it scatters in the air as dust, worsening the working environment. Such fine powder requires treatment such as regeneration into granules by some means. Many proposals have been made in the past regarding methods for improving the solubility of polymer powders or for improving the solubility incidentally for the purpose of dust prevention. For example, a method of kneading water or a water-containing hydrophilic solvent with polymer flocculant powder and drying the mixture (Japanese Patent Application Laid-Open No. 49-1998-1)
83681), if the ratio of water to the powder is small, the adhesive granulation effect will be poor and it will be difficult to produce granules, and if the ratio is too large, it will become a so-called "dango"-like mass, which will cause damage to the vessel walls and stirring. Stable production is extremely difficult as adhesion to the blades occurs and drying time becomes extremely long. In addition, in the case of water-containing hydrophilic organic solvents, there are few problems in the kneading process, but in the drying process, when drying in a closed system to recover the organic solvent, as the solvent recovery progresses, "chirstone"-like formations occur in the dryer. Huge hard lumps form, which seriously impede drying and subsequent grinding. In addition, this method employs a top spraying method of water or a water-containing hydrophilic solvent, which has the disadvantage that spray holes are likely to be clogged. especially
This is not suitable as a method for granulating powder with a large content of fine particles of 200 mesh or less. In addition, in the method of mixing an inorganic salt containing water of crystallization (Japanese Patent Application Laid-Open No. 50-13278), even when a small amount of an inorganic salt containing water of crystallization is added, the contact portion is mixed at the same time as it comes into contact with the polymer powder. This has the disadvantage that the mixing operation is significantly hindered by the progress of "dango"-like agglomeration. Even if this lump is pulverized by some method, it will remain granular for several days after production, but it will gradually solidify after that, causing problems in handling and solubility, making it unstable as a product. , has inferior practical value. Next, in the method of adding a deliquescent inorganic substance (Japanese Patent Application Laid-Open No. 53-34843), powdering can be prevented to some extent, but dispersibility and solubility in water are not improved, and adding a small amount is not effective. Moreover, since it contains a deliquescent substance, it is highly hygroscopic and has the disadvantage of caking during storage or handling. As a result of intensive research to eliminate the above-mentioned deficiencies of the prior art, the present inventors have discovered a polymer powder, a concentrated inorganic salt aqueous solution that does not substantially dissolve the powder, and a concentrated polyethylene glycol solution that does not substantially dissolve the polymer powder. By uniformly stirring and kneading the aqueous solution and pulverizing it, there is no need to add it to the water little by little.
Even if added all at once, it is easily dispersed in water and dissolved in a short time. In addition, there is extremely little dust scattering.
The inventors have discovered a method for producing a polymer composition that does not substantially generate dust, and have completed the invention. That is, (a) a water-soluble acrylamide-based high polymer powder (50 to 90 wt.
%), (b) the concentration of the salt containing one or more water-soluble inorganic salts that do not substantially dissolve the above (a) is
Highly concentrated aqueous solution of 20 wt% or more (9 to 49 wt%) and (c) an average molecular weight of 2000 that does not substantially dissolve the above (a)
~40 of polyethylene glycol with ~20000
-70 wt% aqueous solution (1 to 10 wt%) and adjust the amount of water added within the range of 7 to 40 wt% based on the final polymer composition,
Provided is a method for producing a water-soluble acrylamide-based high polymer composition, which comprises stirring and kneading the mixture of (b) and (c) to form small agglomerates of 3 cm or less, and then pulverizing the mixture into 6 meshes or less. It is something to do. During normal transportation, storage and handling, the polymer composition obtained by the production method of the present invention
There is no substantial granule disintegration, quality stability is good, and it is extremely unlikely that the granules will solidify into a "dango" shape. Moreover, the polymer composition obtained according to the present invention
There is almost no adhesion to the inner wall of the kneader or stirring blades, and removal from the kneader is extremely easy, resulting in good workability. Also, when dissolving, there is no need to add small amounts to water, and the entire predetermined amount can be added for a short period of time, e.g.
It is possible to add at a rate of 100Kg/min. If necessary, it is possible to prepare a thick viscous aqueous solution or aqueous gel with a polymer concentration of 10 wt% or more without any problems and in a short time. The solubility of polymer powder containing a large amount of fine powder can be significantly improved. Furthermore, as mentioned above, not only can the so-called "mako" be not generated during dissolution and it can be rapidly dissolved.
An extremely advantageous advantage is that no dust is generated, which is always a problem when handling fine powders. Therefore, the labor required for the dissolution operation is greatly reduced, and no special feeding equipment is required for the addition operation. There is a close relationship between the particle size of polymer powder and its solubility in water. The smaller the particle size, the faster the dissolution time, and at the same time, fine particles are closely related to the generation of so-called "mako" and dust. On the other hand, if the particle size is coarse, the problems of "mamako" and dust will be reduced, but the dissolution time will be significantly longer, which will be inefficient and will likely cause troubles such as clogging of the supply device. Therefore, during the production of polymer powder, efforts are being made to adjust the powder particle size within a certain range by pulverizing, sieving, classifying, and the like. Coarse particles can be re-pulverized and are not much of a problem, but fine particles, particularly fine powders of 200 mesh or less, cause the aforementioned "mamako" and dust generation, so their utility value is low if left as is. ,
This is not desirable in terms of production efficiency and economy. A feature of the present invention is that the basic effects are achieved by using a highly concentrated aqueous solution of an inorganic salt. In the highly concentrated aqueous solution of the inorganic salt used in the present invention, the acrylamide-based high molecular weight polymer having ordinary water solubility does not substantially dissolve, but only provides a wet or slightly swollen state. In the present invention, stirring is indispensable, and the particles are in a suitable state, that is, the granules are aggregation of fine particles, are moderately strong, do not disintegrate when handled, and when added to water, quickly disintegrate and disperse. This is a necessary means to obtain good solubility. In addition,
The necessity of stirring and kneading is clear from the fact that when a mixture of a highly concentrated aqueous solution and polymer powder is simply heated externally without stirring, it does not form the desired granular shape, but instead becomes a spongy block. It is. If the concentration of the inorganic salt aqueous solution is low and has the ability to dissolve the polymer powder, a hard "dango"-like gel is generated and the effects of the present invention cannot be exhibited. but,
In a highly concentrated aqueous solution with a salt concentration of 20 wt% or more, the presence of solid salts in the polymer powder hardly poses an obstacle to the implementation of the present invention. Inorganic salts include KCl, K ₂ SO ₄ , K ₂ CO ₃ ,
_NaCl , _NaNO3 , _NaCO3 , _Na3PO4 , _NH4Cl ,
(NH ₄ ) ₂ SO ₄ , CaCl ₂ , Ca(NO ₃ ) ₂ , MgCl ₂ ,
Examples include MgSO ₄ , AlCl ₃ , Al ₂ (SO ₄ ) ₃ , etc.
Since polyvalent metal salts can sometimes make the polymer water insoluble, their range of use is severely limited. provides a highly concentrated aqueous solution with the properties necessary to produce a superior granular polymer composition;
In addition, from the economical point of view of the amount used, sodium sulfate and sodium carbonate are most preferred in the present invention. In the present invention, if a highly concentrated aqueous solution (20 wt% or more) of alkali metal neutral salts of sulfuric acid and carbonic acid is used, it is possible to increase the content ratio of water-soluble acrylamide-based high polymer powder in the polymer composition. . This is important from the standpoint of storage stability of the obtained polymer composition, especially prevention of block formation during the storage period, as well as ease of kneading and pulverization in the manufacturing process of the polymer composition. It also has a lot to do with ease of use. Similarly, adjusting the water ratio to the entire polymer composition within the range of 7 to 40 wt% is also an essential requirement for exhibiting the effects of the present invention. When carrying out the present invention, it is desirable to control the temperature to 25 to 35°C. At temperatures below 10°C, it takes a long time to knead the inorganic salt aqueous solution and polyethylene glycol aqueous solution with the polymer powder to form a small lump of fine particles appropriately aggregated. On the other hand, if the temperature is 50°C or higher, coarse lumps will rapidly form in the initial stage of kneading, requiring extra kneading operations to break them up into suitable small lumps, which may adversely affect quality. It is also important for manufacturing to always operate under constant conditions. Therefore, it is most preferable to carry out kneading and the like at 25°C to 35°C, which does not require excessive heating or cooling. Therefore, the high concentration inorganic salt aqueous solution of 20% or more as used in the present invention refers to the concentration at 25 to 35°C. In addition, polyethylene glycol aqueous solution (40~
70wt%) reduces the load on the stirrer during kneading,
It is an additive necessary to achieve the desired effect in a short time, and it further improves the grindability and is commonly used as a general grinding agent similar to the dry polymer of the kneaded product small lumps in a water-containing state. Useful for machine processing. If this polyethylene glycol has a low molecular weight, it will not be effective in terms of workability during pulverization or kneading, and if the molecular weight is too high, it will not exhibit the desired effect. Therefore, in carrying out the present invention,
Polyethylene glycol having a preferred average molecular weight in the range of 2,000 to 20,000 is particularly effective. Since these are solid at room temperature, it is necessary to add them as an aqueous solution in order to mix them homogeneously, and a highly concentrated aqueous solution (40 to 70 wt%) that does not substantially dissolve the acrylamide polymer powder is particularly preferred.
The effects of the present invention can be fully exhibited when the amount of the polyethylene glycol aqueous solution added is in the range of 1 to 10 wt% based on the polymer composition. The manufacturing method of the present invention makes effective use of fine powder, which has low utility value in normal methods because it has a lot of dust and easily generates "mamako", and requires recycling treatment such as granulation, and is an inexpensive and simple method. As a result, a polymer composition can be obtained which maximizes the characteristics of fine powder, which is easily dispersible in water without any dust problems, and which dissolves quickly. The water-soluble acrylamide-based high polymer powder applicable to the present invention includes polyacrylamide, polyacrylamide partial hydrolyzate, acrylamide-acrylate copolymer polysodium acrylate, acrylamide-dimethylaminoethyl methacrylate, and/or its quaternary chemical compound copolymers, etc. Furthermore, the polymer composition obtained by the present invention can be widely used as a sludge flocculation accelerator, a dehydrating agent, a thickener, a paper-making sticky agent, and the like. Examples will be shown below, but the present invention is not limited thereto. Example 1 30 kg of a 25% aqueous solution of sodium carbonate (30°C) and 5 kg of a 60% aqueous solution of polyethylene glycol with an average molecular weight of 4000 were placed in a 300 capacity double-arm kneader (SUS304) and mixed, and then polyacrylamide with an average molecular weight of 8 million was mixed. Powder (20-60 mesh 5
%, 60-200 mesh 52%, 200 mesh or less 43
%) 65Kg and mix at 100rpm. After about 5 minutes, it becomes a little viscous, but it gradually begins to form into small lumps, and after about 10 minutes, it has loosened into small lumps with a diameter of about 5 cm or less, and after 20 minutes, it has become a granular lump with a maximum diameter of about 2 cm or less. Summer. This was taken out from the kneader, and the entire amount was pulverized in a hammer mill (equipped with a screen having 2 mm diameter holes) for about 15 minutes to obtain moist granules in the form of agglomerated fine particles. This composition has 99.7% of 6 to 200 meshes, 0.3% of 200 meshes or less, 28.9% volatile content (moisture) after drying at 105℃ for 120 minutes. not generated,
Stirring was continued and a uniform viscous aqueous solution was obtained after 30 minutes. No dust was observed at all. Example 2 A stainless steel ribbon mixer with a total capacity of 4 and 25
% sodium sulfate aqueous solution (30℃) and 15 g of a 50% aqueous solution of polyethylene glycol with an average molecular weight of 10,000 were added, and while stirring at 80 rpm, acrylamide-dimethylaminoethyl methacrylate methyl chloride quaternized copolymer (50 mol%) copolymer was added. Powder (apparent average molecular weight approximately 2.3 million, 16 to 200 mesh)
62.8%, 200 mesh or less (37.2%)) was added in about 5 minutes, and stirring and kneading was continued for another 10 minutes to make sure that the entire particle mass was 1 cm or less and that they did not adhere to each other, and then the stirring was stopped. and removed from the ribbon mixer. Almost no adhesion was observed on the inner wall of the ribbon mixer and stirring blades after discharge. The taken out small lumps were ground in a feather mill using a 2 mm hole screen (moisture 23.6%).
Granules were obtained having a particle size of 99.7% 200 mesh and 0.3% below 200 mesh. There was no dusting at all before and after the crushing operation. Tap water in 2 beakers
2.9 g of this granular composition was added instantly while stirring at 100 rpm using a jar tester, but it was uniformly dispersed in the water within 10 seconds, and by continuing to stir for 15 minutes, a uniform aqueous solution was obtained. It became. Examples 3 to 7 Prepared compositions were prepared in the same manner as in Example 2 at the proportions shown in Table 1. The test results of the obtained compositions are shown in Table 1 and Table 2 as a comparative control.

【table】

【table】

【table】

[Table] Comparative Example 1 The same procedure as Example 3 was carried out except that the PEG aqueous solution was omitted. Approximately 3 minutes after the start of stirring, the stirring load was increased to a maximum current of 5 amperes (in the case of Example 3, the maximum current was 2 amperes), and after approximately 15 minutes, it became a hard resin-like lump and was gradually broken down into small pieces. After about 30 minutes, a kneaded product similar to that of Example 3 was obtained. The crushability is slightly worse, about 3% compared to Example 3.
It took twice as long. Comparative Example 2 An attempt was made to operate in the same manner as in Example 2, except that water was used instead of the 25% aqueous sodium sulfate solution.
Coarse lumps (more than 5 cm) of hard resin-like powder inside occurred in some areas, and some of the powder remained as it was, with large adhesion to the stirring blades and inner walls, and the load increased rapidly. Stirring became impossible. Draining the mixture from the ribbon mixer was difficult. Comparative Example 3 In a stainless steel ribbon mixer with a total capacity of 4, 645 g of the polymer powder used in Example 3 and 323 g of sodium carbonate (light ash) were placed and mixed for 5 minutes, and then 32 g of water was added and mixed. Partially “Dango”
The stirring load increased significantly due to the formation of lumps, but by continuing to stir for about 30 minutes, the particles were broken down into small particles (less than about 5 mm in diameter), but the temperature rose to 55°C due to friction during stirring. . Add 3.1g of the mixture thus obtained to 2 beakers and 11g of tap water.
When the solution was added all at once while stirring at 100 rpm using a jar tester, no lumps were generated, but it took about 75 minutes to form a uniform aqueous solution due to the presence of hard lumps with a diameter of 3 mm.

Claims (1)

[Claims] 1. The maximum particle size is 16 mesh or less, and 200 mesh
Water-soluble acrylamide-based high polymer powder containing 70% or less of fine particles below the mesh size (50~
90wt.%), and the salt concentration contains one or more water-soluble inorganic salts that do not substantially dissolve the above.
A highly concentrated aqueous solution of 20wt.% or more (9 to 49wt.%) and an average molecular weight of 2000 that does not substantially dissolve the above.
~40 of polyethylene glycol with ~20000
~70wt.% aqueous solution (1~10wt.%) is blended, and the amount of water added is 7~70wt.% to the final polymer composition.
A water-soluble acrylamide-based high polymer composition, which is adjusted within the range of 40wt.%, and is characterized by stirring and kneading the mixture of the above, and, forming small lumps of 3 cm or less, and then pulverizing them into 6 meshes or less. How things are manufactured.