JPS6348337A - Production of composite water-absorptive plastic material - Google Patents

Abstract

PURPOSE:To obtain the titled composite material which is excellent in water absorptivity and water retentivity and can give nonblocking agricultural films, etc., by kneading a finely powdered highly water-absorptive resin treated with a surfactant with a plastic material. CONSTITUTION:A finely powdered highly water-absorptive resin (A) of a mean particles diameter <=100mu, comprising a vinyl acetate/acrylate copolymer sapondificate, etc., is treated with a e.g., a nonionic surfactant (B) in an A to B ratio of 90-10/10-90 by mechanical mixing in, e.g., a ball mill, and the obtained mixture is mixed with a powdery, particulate, palletized or similar plastic material (C) (e.g., low-density PE or ethylene/vinyl acetate copolymer). The resulting mixture is kneaded with rolls, a Banbury mixer, a vented twin- screw extruder or the like.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a water-absorbing plastic composite material. There are many known water-absorbent plastic composite materials that have been given water-absorbing properties.
Even if this is mixed directly into plastic materials, it is difficult to impart sufficient water absorbency as a high-quality composite material. This is because secondary agglomeration occurs to produce coarse particles (so-called "puffs"), and insufficient water dispersion causes a foaming phenomenon, resulting in "pinholes" in the resulting glass composite material. Furthermore, a large amount of shearing energy is required during kneading, and the resulting heat generation causes the kneaded material to decompose, resulting in a decrease in performance.

The present inventors have discovered that by mixing finely powdered superabsorbent resin with mineral oil, plasticizer, etc. in advance, moisture absorption during handling and storage, and scattering that occurs during mixing with resin or rubber, can be prevented. proposed a method to prevent the
860) 7B. This method also solves the above problems to some extent. However, there were cases in which sufficient effects could not be obtained with this method.
Using copolymer as a plastic material, fi! When making industrial film, this method is the best! The blocking of the film after the Iν film is large over time, and there is a point where it cannot be used as an agricultural film.The present inventors have conducted various studies to eliminate the drawbacks of the conventional method.
A surfactant that has excellent affinity for plastics. By kneading the finely powdered superabsorbent resin that has been pre-treated under various pressures into the plastic material, the finely powdered superabsorbent resin is uniformly dispersed. They discovered what could be done and completed the present invention.

<Means for Solving the Interval Opening Point> The present invention is a method for producing a water-absorbing public plastic composite material in which a finely powdered super-absorbent resin is treated with a surfactant and then kneaded with a plastic material.

The finely powdered super absorbent powder f1 ¥1 (hereinafter referred to as "container") used in the present invention is commonly used, such as a saponified product of acetic acid and 2 μm 7 chloride acid ester copolymer, imbutylene-anhydrous Salt of cross-linked product of modified maleic acid copolymer, cross-v! ? Examples include polyacrylic acid (salt) having a structure, a salt of H powder-acrylic acid copolymer, and a modified product of polyethylene oxide. However, since it is necessary to have strong gel strength after water absorption, no gel decay, and long-term durability, saponified vinyl acetate-acrylic acid ester copolymer or modified isobutylene-maleic anhydride copolymer is required. A salt of a crosslinked product of is preferably used. These superabsorbent resins can have a water absorption capacity of 50 to 1000 times their own weight, and those having a water absorption capacity of 100 to 500 times their own weight are more preferable because the gel strength after water absorption is comparable to that of the fine powder. The particle size of the shaped super absorbent resin is preferably as fine as possible from the viewpoint of physical properties of the final water absorbent plastic composite product, and the average particle size is 100μ or less, particularly preferably 1.
It is desirable that it is 0μ or less.

Further, a surfactant (hereinafter referred to as (B)) used in the present invention.

) are commonly used, anionic,
Cationic, nonionic, and amphoteric types can be used.
J or a combination of two or more types can be used. Specifically, polyoxyethylene alkyl ethers, polyoxyethylene aryl μ ethers, polyoxyethylene alkyl esters, sobitan alkyl esters/L's, sorbitanic acid fatty acid esters, polyoxyethylene sorbitan ethers, 〃-alkyl esters, glycerin, pentaerythri)-/L',)! Examples include J Methyl-propane, alkyl esters of polyhydric alcohols such as sugars, polyoxyethylene derivatives, polyoxyethylene alkylamides, fluorine surfactants, phosphoricone surfactants, etc. Especially, super absorbent resins. Nonionic surfactants are preferable in order to suppress the decrease in water absorption capacity, etc., and sorbitan acid fatty acid esters/L's are particularly preferable because they have good affinity with particles and are effective with a small amount. The plastic material used as the matrix of the plastic composite may be either thermosetting or thermoplastic, and may be soft, hard, or foamed, and may be made of synthetic rubber or other efstomer without any problem. In particular, polyethylene, ethylene-rh vinyl acid copolymer or saponified product thereof, chlorinated polyethylene, chlorinated polyprene, sulfonated polyethylene, ethylene-isobutylene copolymer, ethylene-acrylic acid copolymer, polychloride Vinyl or its copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, natural rubber, chloroprene rubber, isopt
/ rubber is preferable 〇Also, the ratio of light used in (4) and (B) varies depending on the respective use and cannot be limited, but it is preferably in the range of AfB = 90/10 to 10/90. .

In addition, in order to obtain a plastic material with high water absorption, (3
) is essential.

In the present invention, the method of treating the congeal with CB+ is a method of mechanically mixing the convict and (B) in a commonly used laika, blender with heater, ball mill, mixer, etc., or toluene, Examples include a method of mixing in the presence of a suitable solvent such as ethyl acetate and then adding an activating agent to remove P5, but it is preferable to carry out the process under conditions such that the particles are sufficiently coated with (B).

By further mixing this with a Buchstick material (powder, granules, pellets, etc.) and then mechanically kneading it, a water-absorbing plastic composite with excellent uniformity can be produced. In the case of the present invention, carbon black,
Inorganic fillers, lubricants, ultraviolet inhibitors, pigments, fungicides, agricultural preventives, and the like can be mixed as appropriate.

<Examples> The present invention will be explained in more detail by examples below.
Although not limited by these, the dispersibility of the finely powdered superabsorbent resin in the material is approximately 200μ press sheet, and the water absorption of the plastic composite is determined by observation with a microscope (100x magnification). ◎ -A Water absorption rate (@mouth □ × 100 A: Weight before water absorption, (f) B: Weight after immersion in water 48 hours 1 iJl] ffi if) Experiment l super absorbent resin (Sumikagel■5P-
510, average particle size -10 μm, manufactured by Sumima Kagaku Kogyo) 50
After thoroughly mixing 0 f tIC with 300 F of a nonionic surfactant (Tsurupon 5-60, Toho Chiba Kagaku 1 Shiba Fl), using a blender equipped with a heater,
Mechanical mixing was performed at 0 to 90°C for about 20 minutes, and the surface of the Sumikagel ■5P-510 particles was coated with Tsurpone ■seo.

Experiment 2 In addition to Sumikagel ■5P-510, salts of crosslinked products of modified inbutylene-maleic anhydride copolymer (KI gel φ20
1, Kurareiso 7" manufactured by Ren Chemical Co., Ltd., average particle size -8
The procedure was the same as in Experiment 1 except that KI
The surface of Ge/L10201K particles was coated with Turpon ■5-60 Example 1 Ethylene-vinyl acid acetate copolymer (evatate H2O22
For 1000 tons of beret (manufactured by Sumikagaku Kogyo Co., Ltd.), Sumikagel heated with 5-60 tsurpon obtained in Experiment 1 5
Add 40f of P-510 mixture, low/l' temperature 12
After kneading at 0°C, the mixture was further extruded into υ strands using an extruder and cut into pellets. Using this pellet, a press sheet of approximately 200 μm was made. The dispersibility of Sumikagel ■5P-510 was observed under a microscope, and the dispersion of Sumikagel ■5P-510 was found to be uniform.

Furthermore, the water absorption rate of the press sheet was 5.1%. 501 of the mixture was added to KI Gel ■201, kneaded at a low/L' temperature of 160°C, and then extruded into strands using an extruder and cut into pellets. Using this pellet, approximately A 200μ press sheet was made in the same manner as in Example 1, and KIgeyo2011
As a result of examining the dispersibility of (), it was found that the dispersion in KI Gel ■201 was uniform.

Further, the water absorption rate of the press sheet was 8.2%.

Example 8 Sumikage A treated with Tsurupon oS-60 obtained in Experiment 1
/'' 150 parts of a mixture of 5P-510, 80 f1 of dibutyl phthalate, and polyvinyl chloride, 11/ (7 millimeter FS, manufactured by Sumima Kagaku Kogyo) were mixed in a Henschel mixer, and mixed at 150°C for 5 minutes at 1 M m After that, a press sheet was molded for about 2 days.The dispersion of Numikage φ5P-510 in the obtained press sheet was uniform.

Moreover, the water absorption rate of the press sheet was 180%.

Comparative Example 1 Ethylene-vinyl acetate copolymer (evatate)! 202
2. Add 251 parts of Sumikagel o8P-510 to Beret 100OF (manufactured by Sumika Kagaku Kogyo).Except for the following, Example 1
In the same manner as above, make a press sheet of about 200μ, and reduce the elasticity of Sumikage A・■5P-510 by 1 by 4 times.
As a result, many forts V of Sumikagenoyo 5P-510 were observed, and the dispersion was extremely non-uniform compared to Example 1 ◇ Also, the water absorption rate of the press sheet was 8.5%, which was different from Example 1. Water absorption was poor.

Comparative Example 2 KI Ge Iv ■ 201K was used at 81F for Beret 1000F of low static polyethylene (Dow Poly ■, manufactured by Asahi Tau Co., Ltd.)
A press sheet of about 200 μm was made in the same manner as in Example 2, except that the following was added. As a result of examining the dispersibility of KX Ge-201, a large amount of aggregation was observed in KX Ge-201.
In comparison, the kana-shi distribution was non-uniform.

Moreover, the water absorption rate of the press sheet was 2.8 years old, which was slightly inferior.

<Effects of the Invention> By the method of the present invention, a finely powdered superabsorbent resin can be uniformly dispersed in a plastic material. In addition, water is sufficiently dispersed during kneading, and the occurrence of "pinholes" can be prevented. Furthermore, since the shearing energy during mixing and heating is small, heat generation is reduced and decomposition of the mixed material can be prevented. Therefore, the water-absorbing plastic bonding material produced by the method of the present invention has excellent water absorption and can last for a long time. Niwatashi shows its effect.

Claims (1)

[Claims] A method for producing a water-absorbing plastic composite material, in which a finely powdered super-absorbent resin is treated with a surfactant and then kneaded with a plastic material.