JPH0698307B2 - Method for producing 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 with uniform and strong water-insoluble fine particles having a deodorizing effect. The present invention relates to a method for producing a fixed and supported water-absorbent composite.

[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-absorbing polymers include polyacrylic acid salt crosslinked products, starch-acrylic acid salt graphs and crosslinked products, polyvinyl alcohol-modified crosslinked products, and maleic acid copolymer crosslinked products. It may be desired to have an effect. However, since the polymer itself has little deodorizing effect, a method of adding deodorizing effect by incorporating activated carbon or the like has been considered. However, as a method of blending water-insoluble fine particles such as activated carbon with a water-absorbent polymer, for example, JP-A-56-133028 and JP-A-59-3827.
Japanese Patent Laid-Open Publication No. 1-2003 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,
Moreover, there is a drawback that 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 uniformly and firmly provide water-insoluble fine particles having a deodorizing effect to a water-absorbent polymer powder. It is an object of the present invention to provide a method for easily and efficiently producing a supported water-absorbent composite without deteriorating the working environment.

[Means for Solving the Problem] The method for producing a water-absorbent composite of the present invention is characterized in that water-insoluble fine particles having a deodorant effect are added to and mixed with a water-absorbent polymer powder as an aqueous dispersion. 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. 13495/53, Japanese Patent Publication No. 55-19243), cross-linked polyvinyl alcohol modified product (Japanese Patent Publication No. 54-20093), partially neutralized polyacrylate cross-linked product (Japanese Patent Publication No. -84304, JP-A-56-93716, JP-A-56-16
1408, JP-A-58-71907), a crosslinked isobutylene-maleic anhydride copolymer (JP-A-56-36504) and the like. And, even if these water-absorbing polymers have uniform cross-linking, or they are disclosed in JP-A-58-180233, JP-A-58-117222,
Any of those subjected to a surface cross-linking treatment as disclosed in JP-A-58-42602 can be used without any particular limitation.

As the water-insoluble fine particles having a deodorizing effect, substances having an arbitrary deodorizing effect can be selected regardless of whether they are inorganic or organic.
For example, activated carbon, alumina, silica, zeolite, triazine derivatives and the like can be used.

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, the water-insoluble substance added for the purpose of imparting a deodorizing effect to the water-absorbent polymer is uneconomical because if the particles are too large, it is necessary to increase the addition amount in order to obtain a sufficiently dispersed state. However, in some cases, the sufficient effect may not be obtained.
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, fine particles are usually
It is preferably 50 μm or less, more preferably 10 μm or less.

The amount of the water-insoluble fine particles in the present invention can be in a wide range, but is usually preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the water-absorbing polymer powder. If it is less than 0.01 parts by weight, the effect of adding water-insoluble fine particles may not be observed, and on the contrary, if the amount exceeds 10 parts by weight, the probability that the water-insoluble fine particles adhere to each other increases, and the effect corresponding to the addition amount is improved. Is difficult to recognize. More preferably
It is in the range of 0.1 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 able to be firmly held. Water-insoluble fine particles when the amount used is less than 1 part In some cases, the water-absorbing polymer powder may be insufficiently supported, and even if the amount exceeds 30 parts, the effect cannot be expected to be improved, and the energy cost at the time of drying is rather increased.

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, but 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 specific examples merely describe one embodiment of the present invention, and it goes without saying that a batch type mixing operation is adopted, let alone a continuous mixing operation using another mixing apparatus. 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 Examples and Comparative Examples Powder deodorant (Shuklenz, manufactured by Lhasa Industry) or powder deodorant (K Fresh, manufactured by Teikoku Kako) was mixed with water to prepare an aqueous dispersion of water-insoluble fine particles. . The water dispersion was added to a water-absorbent polymer powder (Aqualic CA, manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.) and mixed using a "Turbulizer" (manufactured by Hosokawa Micron Co., Ltd.) to prepare a water-absorbent complex (1 )-(5) (Examples 1-5) were obtained.

Further, as a comparative example, the same as the above-mentioned example except that the water-insoluble fine particles were added to the water-absorbing polymer powder as they were without mixing them into an aqueous dispersion, and the powders were mixed with each other, followed by spraying water. The operation was repeated to obtain comparative water absorbent composites (1) to (4) (Comparative Examples 1 to 4). 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
3 g of the water-absorbing complex remaining on the 200-mesh wire net was collected, put in separate 125 ml vials and capped. Next, i-propyl mercaptan having an initial concentration of 100 ppm and 3000 ppm of ammonia gas were introduced, and the amount of each gas remaining after 30 minutes was measured by the detector tube (Kitagawa method) method to obtain the residual rate (%). First result
Shown in the table.

The absorbent composites (1) to (5) according to the present invention showed an excellent deodorizing effect on i-propylmercaptan and ammonia.

[Effect of the Invention] By the production method of the present invention, water-insoluble fine particles having a deodorizing effect are uniformly and firmly adhered to the water-absorbent polymer powder.
The supported water-absorbent composite 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 having a deodorizing effect 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.