JPH0698306B2 - Manufacturing method of water-absorbent composite - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a water-absorbing composite, and more specifically to water-absorbing polymer powder in which water-insoluble fine particles are uniformly and firmly fixed and carried. The present invention relates to a method for producing a sex complex.

[Prior Art] In recent years, a water-absorbing polymer that absorbs several tens to several hundreds of times its own weight of water has been developed, and is used in the field of sanitary napkins, paper diapers and other sanitary products, as well as in the fields of agriculture and forestry, civil engineering, etc. Widely used.

Examples of these water-absorbent polymers include polyacrylic acid salt crosslinked products, starch-acrylic acid salt graft crosslinked products, polyvinyl alcohol-modified crosslinked products, and maleic acid copolymer crosslinked products, and various other properties such as weather resistance and fluidity. For the purpose of improving the above properties, water-absorbing composites in which various water-insoluble fine particles are mixed with the above water-absorbing polymer have been proposed.
However, as a method of blending water-insoluble fine particles with a water-absorbing polymer, for example, JP-A-56-133028 and JP-A-59-59
-38271 and the like only disclose a method in which a water-absorbent polymer powder and water-insoluble fine particles are simply mixed in a powder form or water is added after mixing. In such a composite, the water-absorbent polymer powder and the water-insoluble fine particles are simply physically mixed or in a state close to it, and the mixed state is also non-uniform, so that the water-insoluble fine particles are mixed. The effect is uncertain and insufficient, and the water-insoluble fine particles are easily separated during transportation and storage. Furthermore, since the water-insoluble fine particles are handled in the form of powder, there is a serious deterioration of the working environment due to the dust, and there is a problem that cannot be ignored in terms of occupational hygiene.

[Problems to be Solved by the Invention] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a water-absorbent polymer powder with water-insoluble fine particles uniformly and firmly supported thereon It is an object of the present invention to provide a method for easily and efficiently producing a sex composite without deteriorating the working environment.

[Means for Solving the Problem] The method for producing the water-absorbent composite of the present invention is characterized by adding water-insoluble fine particles to the water-absorbent polymer powder as an aqueous dispersion and mixing them. The water-absorbent composite in the present invention means one in which water-insoluble fine particles are uniformly carried on the water-absorbent polymer.

[Operation] 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 a water-absorbing polymer include starch-acrylonitrile graft copolymer hydrolyzate (Japanese Patent Publication No. 49-43395), in addition to the polyacrylate cross-linked product.
Neutralized product of starch-acrylic acid graft polymer
53-46199, JP-B-55-21041), acrylic acid ester-
Saponification product of vinyl acetate copolymer (Japanese Patent Publication No. 53-13495, Japanese Patent Publication No. 55-19243), cross-linked polyvinyl alcohol modified product (Japanese Patent Publication No. 54-20093), partially neutralized polyacrylic acid cross-linked product (Japanese Patent Publication No. 55- 84304, JP-A-56-93716, JP-A-56-1614
08, JP-A-58-71907), a crosslinked isobutylene-maleic anhydride copolymer (JP-A-56-36504) and the like.
Even if these water-absorbing polymers have uniform cross-linking, or if they are subjected to surface cross-linking treatment as disclosed in JP-A-58-180233, JP-A-58-117222 and JP-A-58-42602. Any of the applied ones can be used without any particular limitation.

As the water-insoluble substance used as the water-insoluble fine particles, any substance can be selected, regardless of whether it is inorganic or organic, depending on the characteristics to be imparted to the water-absorbent polymer. For example, as water-insoluble inorganic substances, aluminum compounds such as aluminum oxide; zinc compounds such as zinc oxide; calcium compounds such as calcium carbonate and gypsum; silicon compounds such as silica;
Metals such as copper, iron, aluminum and nickel; sulfur and the like can be mentioned. Further, as the water-insoluble organic matter,
Various organic pigments, carbon black, etc. may be mentioned, and other antibacterial agents, fluidizing agents, colorants and the like may be appropriately selected according to the purpose.

When the particle diameter of the water-insoluble substance is too large, it is preferable to pulverize it into fine particles in advance and use it. That is, many water-insoluble substances added for the purpose of imparting new physical properties to the water-absorbent polymer are expensive, and if the particles are too large, it is necessary to increase the addition amount in order to obtain a sufficiently dispersed state. It is uneconomical and may not be fully effective. For example, pigments and the like do not exhibit their functions unless they are fine particles. On the other hand, fine particles having an appropriate size and shape can be firmly entangled and firmly attached to the water-absorbent polymer surface layer swollen by the water supplied together with the fine particles. In order to obtain the above various effects, it is preferable that the fine particles have a particle size of usually 50 μm or less, preferably 10 μm or less.

The amount of the water-insoluble fine particles in the present invention can be set in a wide range, but usually 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight of the water-absorbing polymer powder. If it is less than 0.1 part by weight, the effect of adding water-insoluble fine particles may not be observed, and conversely if the amount is more than 10 parts by weight, the probability of water-insoluble fine particles sticking to each other increases, improving the effect in proportion to the addition amount. Is difficult to recognize. More preferably
It is in the range of 0.3 to 5 parts by weight.

In carrying out the present invention, the water-insoluble fine particles are used as an aqueous dispersion. The aqueous dispersion referred to here is a liquid 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 the low viscosity does not hinder the present invention, but substantially the same viscosity as that of water can be used. For example, a slurry, a suspension, an emulsified liquid, and the like are included in the water dispersion liquid of the present invention. When the water-insoluble fine particles are produced in the state of an aqueous dispersion, they can be used as they are without being dried or in a state of being concentrated to some extent. Particularly, in this case, the step of drying the water-insoluble fine particles and the step of pulverizing the dried material can be omitted, which is economical.

The amount of water for forming the aqueous dispersion may be in a wide range, but it is usually preferable to set the ratio of 1 to 30 parts with respect to 100 parts by weight (hereinafter abbreviated as parts) of the water-absorbing polymer powder. When water is added, the surface layer of the water-absorbent polymer swells, and the fine particles supplied at the same time as water are held in a state of being held in the surface layer, whereby the water-absorbent polymer can be firmly supported. If the amount used is less than 1 part, the water-insoluble fine particles may not be sufficiently supported on the water-absorbing polymer powder, and if the amount exceeds 30 parts, the effect cannot be expected to be improved, and the energy cost during drying is rather high. Will result in a rise in.

As a device for mixing the water-absorbent polymer powder and the water dispersion liquid, a mixing device well known to those skilled in the art can be used without limitation, and as a mixing device that can be suitably used, for example, a high speed rotating paddle type mixer can be mentioned.

A high speed rotating paddle type mixer is a machine in which a rotor equipped with a large number of paddles in a cylindrical container rotates at high speed to mechanically mix or disperse two or more kinds of powder, or powder and liquid. For example, "Turbulizer" and "Sand Turbo" (both manufactured by Hosokawa Micron Corporation) can be mentioned.

To explain a specific embodiment for carrying out the present invention using such a mixing device, for example, a water-absorbing polymer is introduced 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 a powder and an aqueous dispersion are continuously or intermittently supplied and the mixture is continuously or intermittently discharged from the container. At that time, the degree of mixing can be freely controlled by adjusting the supply amount and the discharge amount.

It should be noted that the above-mentioned specific examples merely describe one embodiment of the present invention, and needless to say continuous mixing operation using another mixing apparatus, and of course batch-type mixing operation may be adopted. It is possible.

The water-absorbent composite obtained by the above operation can be dried to an appropriate degree depending on the purpose of use and the water content, or can be used as it 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 the water-insoluble fine particles.

[Examples] Experimental Example 1 Fine particle silica ("Aerosil 200" manufactured by Nippon Aerosil Co., Ltd.) or diatomaceous earth (Radiolite F manufactured by Showa Kagaku) was mixed with water to prepare an aqueous dispersion of water-insoluble particles. did. This water dispersion was added to a water-absorbent polymer powder (Aqualic CA, manufactured by Nippon Shokubai Kagaku Co., Ltd.) and mixed using a "Turbulizer" (manufactured by Hosokawa Micron Co., Ltd.) to obtain a water-absorbent complex ( 1)-(4) (Examples 1-4) were obtained.

Further, as a comparative example, the same as Example 1 except that the water-insoluble fine particles were added to the water-absorbent polymer powder as they were without mixing them into an aqueous dispersion and the powders were mixed with each other, followed by spraying water. By repeating the operation, the comparative water absorbent composite (1)
-(5) (Comparative Examples 1-5) were obtained. The types of fine particles constituting each of them and the amount of water are as shown in Table 1. The comparative example in which the amount of water is 0 is a mixture of the water-insoluble fine particles and the water-absorbing polymer.

The water-absorbent composites of Examples and Comparative Examples obtained were each 10
g was sieved through a 200-mesh wire net, and 5 g of each water-absorbing complex remaining on the 200-mesh wire net was collected. Next, spread each of them evenly on the bottom of a stainless steel cylindrical container with a diameter of 10 cm, and
The fluidity and the adhesiveness to stainless steel were examined by leaving it standing at ℃ and 65% relative humidity. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 4, the fluidity was maintained for a long time even under the moisture absorption condition, and there was almost no adhesion to the metal surface.

Experimental Example 2 Organic pigment powder disazo yellow (Pigment Yellow 1
2) Water-dispersed liquid consisting of 1 part of powder and 5 parts of water was used as a water-absorbing polymer powder (Nippon Shokubai Kagaku Kogyo KK, Aqualic C
A) 100 parts by spraying was added and mixed using a sand turbo (manufactured by Hosokawa Micron Co., Ltd.) to obtain a water absorbent composite (Example 5).

As a comparative example, 1 part of the disperse organic pigment powder, Disazo Yellow, was used as it was without forming the water dispersion liquid 100
A water-absorbent composite (Comparative Example 6) was obtained by performing the same mixing operation as above except that the water-absorbent composite was added.

10 g of the resulting water-absorbent composite (Example 5 and Comparative Example 6)
Each was screened with a 200 mesh wire mesh. Visual comparison of the degree of yellow coloring of the water-absorbent composite remaining on the 200-mesh wire net revealed that Example 5 was significantly clearer. Further, in the water-absorbent composite which was sieved out under the wire mesh, a large amount of the organic pigment powder was separated in Comparative Example 6.

[Effects of the Invention] According to the production method of the present invention, a water-absorbent composite in which water-insoluble fine particles are uniformly and firmly adhered and supported on a water-absorbent 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 state of an aqueous dispersion, there is no concern about dust generation and it is extremely suitable in terms of occupational hygiene.

Claims (2)

[Claims] 1. A method for producing a water-absorbing composite, which comprises adding water-insoluble fine particles as an aqueous dispersion to a water-absorbing polymer powder and mixing them. 2. The method for producing a water-absorbent composite according to claim 1, wherein the water used in the water dispersion is 1 to 30 parts by weight with respect to 100 parts by weight of the water-absorbing polymer powder.