JPH04114740A - Preparation of water-absorbing polymer composite - Google Patents

Abstract

PURPOSE:To easily and effectively prepare a water-absorbing polymer composite wherein water-insoluble minute particles are uniformly and strongly fixed and supported by a method wherein an aqueous dispersion containing water-insoluble minute particles and a dispersion stabilizer is added to and mixed with a water- absorbing polymer powder. CONSTITUTION:At first, inorg. or org. water-insoluble minute particles composed of an aluminum compound such as aluminum oxide or org. pigment and a dispersion stabilizer are dispersed in water to prepare an aqueous dispersion. As the dispersion stabilizer, one or more kind of a compound selected from a hydrophilic org. solvent such as ethanol, a water-soluble polymer such as starch and a surfactant such as sodium oleate is used. At this time, the amount of the water of the aqueous dispersion is set to about 1-30 pts.wt. per 100 pts.wt. of a water-absorbing polymer. By this method, a product having water-insoluble minute particles strongly supported thereon is easily and effectively prepared without deteriorating working environment because no powder is handled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a water-absorbing polymer composite, and more specifically, a method for producing a water-absorbing polymer composite in which water-insoluble fine particles and a dispersion stabilizer are uniformly and firmly fixed to a water-absorbing polymer powder. -Relates to a method for producing a supported water-absorbing polymer composite.

[Conventional technology] In recent years, water-absorbing polymers that absorb water tens to hundreds of times their own weight have been developed, and have been used in the impact field of sanitary napkins, disposable diapers, etc., as well as in the fields of agriculture, forestry, and civil engineering. Widely used.

Examples of these water-absorbing polymers include polyacrylate cross-linked products, starch-acrylate graft cross-linked products, polyvinyl alcohol-modified cross-linked products, and maleic acid copolymer cross-linked products, which have various properties such as weather resistance, fluidity, etc. With the aim of improving the properties of water absorbing polymers, water absorbing composites in which various water-insoluble fine particles are blended with the above-mentioned water absorbing polymers have been proposed.

However, as a method for blending water-insoluble fine particles into a water-absorbing polymer, for example, Japanese Patent Laid-Open No. 56-133028 and Japanese Patent Laid-Open No. 59-38271 disclose a method of simply blending water-absorbing polymer powder and water-insoluble fine particles in powder form. Only methods such as mixing or adding mixed condensate are disclosed. In such a composite, the water-absorbing polymer powder and the water-insoluble fine particles are simply physically mixed or in a state close to that, and furthermore, the mixed state is non-uniform;
The effects of incorporating water-insoluble fine particles are uncertain and insufficient, and the water-insoluble fine particles easily separate during transportation and storage. Furthermore, since water-insoluble fine particles are handled in powder form, the working environment is seriously degraded by the dust, which also poses a non-negligible problem in terms of occupational health.

[The problem that the invention tries to solve! ! ] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water-absorbing polymer composite in which water-insoluble fine particles are uniformly and firmly supported on a water-absorbing polymer powder, in a work environment. It is an object of the present invention to provide a method for easily and efficiently manufacturing without causing deterioration of the properties.

[Means for Solving the Problems] The gist of the method for producing a water-absorbing polymer composite of the present invention is to add and mix an aqueous dispersion containing water-insoluble fine particles and a dispersion stabilizer to a water-absorbing polymer powder. . Incidentally, the water-absorbing polymer composite in the present invention refers to one in which water-insoluble fine particles are uniformly supported on a water-absorbing polymer.

[Function] The water-absorbing polymer powder used in the present invention is not particularly limited as long as it is substantially insoluble in water and absorbs water to swell.

Examples of such water-absorbing polymers include, for example, in addition to the above-mentioned crosslinked polyacrylates, hydrolysates of starch-acrylonitrile graft copolymers (Japanese Patent Publication No. 49-4339
5) Neutralized product of starch-acrylic acid graft polymer (
Special Publication No. 53-46199, Special Publication No. 55-21041),
Saponified product of acrylic acid ester-vinyl acetate copolymer (
Special Publication No. 53-13495, Special Publication No. 55-19243),
Cross-linked polyvinyl alcohol modified product (JP-A-54-200
93), Partially neutralized polyacrylate crosslinked product (JP-A-55
-84304, JP-A-56-93716, JP-A-56-
161408, JP-A-58-71907), crosslinked isobutylene-maleic anhydride copolymer (JP-A-56-365)
04) etc. These water-absorbing polymers may have uniform crosslinking, or may be
233, JP-A-58-117222, JP-A-58-42
Any material can be used, even one subjected to surface crosslinking treatment as disclosed in Japanese Patent No. 602, and is not particularly limited.

As the water-insoluble substance used as the water-insoluble fine particles, any substance can be selected depending on the properties desired to be imparted to the water-absorbing polymer, regardless of whether it is inorganic or organic. Compounds: Zinc compounds such as zinc oxide; Calcium compounds such as calcium carbonate and gypsum; Silicon compounds such as silica, copper,
It is diagnosed by metals such as iron, aluminum, nickel; sulfur and others. Further, examples of the water-insoluble organic substance include various organic pigments, carbon black, etc., and other antibacterial agents, fluidizing agents, coloring agents, etc. may be appropriately selected depending on the purpose.

If the particle size of the water-insoluble substance is too large, it is preferable to crush it into fine particles before use. In other words, many water-insoluble substances added for the purpose of imparting new physical properties to water-absorbing polymers are expensive, and if the particles are too large, it is necessary to increase the amount added in order to obtain a sufficient dispersion state. This is uneconomical and may not be sufficiently effective. For example, pigments cannot function unless they are fine particles. On the other hand, if the fine particles have an appropriate size and shape, they can be well entangled with the water-absorbing polymer surface layer that is swollen by the water supplied together with the fine particles, and can be firmly attached.

In order to obtain the various effects mentioned above, the fine particles are usually 50μ
The thickness is preferably 10 μm or less, preferably 10 μm or less.

The amount of water-insoluble fine particles in the present invention can vary widely, but is usually preferably 0.1 to 10 parts by weight per 100 parts by weight of water-absorbing polymer powder. If the amount is less than 0.1 parts by weight, the effect of adding the water-insoluble quasi-particles may not be observed. Conversely, if the amount exceeds 10 parts by weight, the probability that the water-insoluble fine particles will adhere to each other increases, and the amount is not commensurate with the amount added. This is because it becomes difficult to recognize the improvement in effectiveness. More preferably, it is in the range of 1 to 5 parts by weight.

In the present invention, a dispersion stabilizer is used to stably disperse water-insoluble fine particles in water without agglomerating them. It is particularly effective for hydrophobic fine particles. The dispersion stabilizer used in the present invention is not particularly limited and can be used as long as it has been conventionally used to stably disperse water-insoluble fine particles in water. For example, hydrophilic organic solvents such as methanol, ethanol, propatool, butanol, acetonitrile, and dimethylformamide; water-soluble polymers such as polyvinyl alcohol, starch, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, and polyacrylate; Fatty acid salts such as sodium oleate and potassium castor oil, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate, alkylnaphthalenesulfonates, dialkyl sulfosuccinates, alkyl Anionic surfactants such as phosphate ester salts, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl sulfate salts; polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene fatty acid esters,
Nonionic surfactants such as sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, fatty acid ester, oxyethylene-oxypropylene block polymer; alkylamine salts such as laurylamine acetate and stearylamine acetate, lauryl trimethyl ammonium Cationic surfactants such as quaternary ammonium salts such as chloride and stearyltrimethylammonium chloride; amphoteric surfactants such as nilauryldimethylamine oxide; and the like.

The various dispersion stabilizers mentioned above may be used alone or in combination. By adding these stabilizers,
Water-insoluble fine particles that are difficult to disperse in water can be stably dispersed. The amount of dispersion stabilizer used varies depending on the type of dispersion stabilizer added, and is not particularly limited. 0.00 for
The range is preferably 1 to 50 parts, particularly preferably 0.01 parts.
~20 copies.

In carrying out the present invention, the water-insoluble fine particles are used as an aqueous dispersion. The aqueous dispersion herein refers to a dispersion in which the water-insoluble fine particles are uniformly dispersed in water, and has fluidity. In a preferred embodiment, the upper limit of the viscosity is 10,000 cps (25° C.), and although a low viscosity does not pose a problem in the present invention, it is possible to use one having a viscosity substantially comparable to that of water. For example, a slurry, a suspension, an emulsion, and the like are also included in the aqueous dispersion in the present invention. Furthermore, when the water-insoluble fine particles are produced in the form of an aqueous dispersion, they can be used as they are without drying or in a somewhat concentrated state. Particularly in this case, the process of drying the water-insoluble fine particles and the process of pulverizing the dried particles can be omitted, which is economical.

The amount of water to form an aqueous dispersion can vary widely, but is usually 1 to 100 parts per 100 parts of water-absorbing polymer powder.
Preferably, the proportion is 30 parts. By adding water, the surface layer of the water-absorbing polymer swells and becomes in a state where it partially holds the fine particles that are supplied at the same time as water.
It can be firmly supported. If the amount used is less than 1 part, the water-insoluble fine particles may not be supported sufficiently on the water-absorbing polymer powder, and if more than 30 parts are used, no improvement in effectiveness can be expected, and the energy cost during drying may be increased. This results in an increase in

As a device for mixing the water-absorbing polymer powder and the aqueous dispersion, any mixing device well-known to those skilled in the art can be used without restriction, but examples of mixing devices that can be suitably used include, for example, a high-speed rotating paddle type mixer. .

A high-speed rotating paddle type mixer is a machine that mechanically mixes or disperses two or more types of powder, or powder and liquid, by rotating a rotor with many paddles inside a cylindrical container at high speed. For example, "Turbulizer" and "Sand Turbo"
(manufactured by Hosokawa Micron ■), etc.

To describe a specific embodiment of carrying out the present invention using such a mixing device, for example, a water-absorbing polymer is placed into a cylindrical container in which the paddle of the high-speed rotating paddle type mixer is rotating at high speed. A typical example is a method in which the powder and the aqueous dispersion are continuously or intermittently supplied, and the mixture is continuously or intermittently discharged from the container. At this time, the degree of mixing can be freely controlled by adjusting the supply amount and discharge amount.

The above specific example merely describes one embodiment of the present invention, and it goes without saying that a continuous mixing operation using other mixing devices or a batch-type mixing operation may also be adopted. It is possible.

The water-absorbing polymer composite obtained by the above operation can be dried to an appropriate degree depending on the purpose of use and water content, or can be used as is. The drying method is not particularly limited, and any method may be used as long as it does not inhibit the functions of the water-absorbing polymer and water-insoluble fine particles.

[Example] Experimental Example 1 Particulate silica (Aerosil 2001 Nippon Aerosil ■
(manufactured by) or Diaiso ± (Radiolite F, manufactured by Showa Kagaku)
and dispersant [sodium dodecylbenzenesulfonate (D
BS), or Emal 0 (manufactured by Kao) or Emanone 3199 (manufactured by Kao)] and water to prepare an aqueous dispersion of water-insoluble fine particles. This aqueous dispersion was added to water-absorbing polymer powder (Aqualic CA, manufactured by Nippon Shokubai Chemical Co., Ltd.), and "Turbulizer" (manufactured by Hosokawa Micron ■) was added.
Water-absorbing polymer composites (1) to (7) are prepared by mixing using
(Examples 1 to 7) were obtained.

Furthermore, as a comparative example, one without adding water (Comparative Example 1)
, without adding a dispersant (Comparative Example 2.3), and after mixing water-insoluble fine particles with a dispersant without making an aqueous dispersion, they were added to a water-absorbing polymer powder, the powders were mixed, and water was added. The sprayed material (Comparative Example 4) was subjected to the same operations as in the example except for the above to obtain comparative water absorbent composites (11 to (4)).
Comparative Examples 1 to 4) were obtained. The types of fine particles constituting each, the amount of water, etc. are as shown in Table 1.

10 g of the obtained water-absorbing polymer composites of Examples and Comparative Examples were each sieved through a 200-mesh wire mesh, and 5 g of the water-absorbing polymer composites remaining on the 200-mesh wire mesh were collected. Spread evenly on the bottom of a stainless steel cylindrical container at 20°C and relative humidity 70%.
The fluidity and adhesion to stainless steel were examined by standing under these conditions. The results are shown in Table 1.

As shown in Table 1, Examples 1 to 7 maintained fluidity for a long time even under hygroscopic conditions, and had almost no adhesion to metal surfaces.

Experimental Example 2 1 part of organic pigment powder phthalocyanine blue (Pigment Blue 15) powder was dispersed in an aqueous solution consisting of 0.1 part of polyoxyethylene monostearate and 5 parts of water, and water-absorbing polymer powder (Aqualic CA, Nippon Shokubai Chemical Co., Ltd.) was dispersed. The mixture was added to 100 parts of Kogyo (manufactured by Kogyo ■) while being sprayed, and mixed using a sand turbo (manufactured by Hosokawa Micron ■) to obtain a water-absorbing polymer composite (Example 8).

As a comparative example, 1 part of organic pigment powder phthalocyanine blue was added as is to 100 parts of water-absorbing polymer powder without making it into an aqueous dispersion, and mixed using a sand turbo to form a comparative water-absorbing polymer composite (Comparative Example 6). Obtained.

10 g of the obtained water-absorbing polymer composites (Example 8 and Comparative Example 5) were each sieved through a 200-mesh wire mesh.
When the degree of blue coloring of the water-absorbing polymer composite remaining on the 00 mesh wire mesh was visually compared, Example 8 was significantly darker and clearer. Furthermore, in the water-absorbing polymer composite sieved under the wire mesh, a large amount of organic pigment powder was separated in Comparative Example 5.

[Effects of the Invention] According to the production method of the present invention, a water-absorbing polymer composite in which water-insoluble fine particles are uniformly and firmly attached to and supported on a water-absorbing polymer powder can be obtained very easily and efficiently. Moreover, in the method of the present invention, since the water-insoluble fine particles are handled in the form of an aqueous dispersion, there is no concern about the generation of dust, and the method is extremely suitable in terms of occupational hygiene.

Applicant: Nippon Shokubai Chemical Co., Ltd.

Claims (3)

[Claims] (1) A method for producing a water-absorbing polymer composite, which comprises adding and mixing an aqueous dispersion containing water-insoluble fine particles and a dispersion stabilizer to a water-absorbing polymer powder. (2) The water used in the aqueous dispersion is water-absorbing polymer powder 10
0 parts by weight to 1 to 30 parts by weight (1 to 30 parts by weight)
) The method for producing the water-absorbing polymer composite described in (3) The water-absorbing polymer composite according to claim (1) or (2), wherein the dispersion stabilizer is one or more selected from the group consisting of a hydrophilic organic solvent, a water-soluble polymer compound, and a surfactant. How the body is made.