JPS6331539A - Moisture absorbing material - Google Patents

Abstract

PURPOSE:To increase water absorbing quantity and a water absorbing speed with respect to ion-containing water, by treating an ionic highly water-absorptive material or a water absorbing material containing the same with a nonionic highly water-absorptive material to form a moisture absorbing material. CONSTITUTION:When an ionic hyghly water-absorptive material such as an acrylic copolymer is powdery, a nonionic highly water-absorptive material such as a polyethylene oxide crosslinked polymer dissolved in a volatile org. solvent is mixed with the powdery ionic highly water-absorptive material under stirring. Subsequently, the org. solvent is volatilized and removed and the lumpy substance obtained is ground to obtain a moisture absorbing material. When the ionic highly water-absorptive material has a structure such as film or sheet- like cloth, said structure is immersed in a liquid and squeezed with a mangle to obtain the moisture absorbing material. When said absorbing material has a yarn structure, a method corresponding to the sizing and warping of a fabric is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a water-absorbing material, and more particularly to a water-absorbing material that has excellent performance against ion-containing water and excellent durability.

(Prior art) Many reports have been made in recent years regarding super absorbent materials, and representative examples include ionic super absorbent materials such as hydrolyzed products obtained by graft polymerizing polyacrylonitrile to starch, and starch. Graft copolymerization of acrylic acid with acrylic acid, crosslinked polymer of carboxymethyl cellulose, hydrolysis of polyacrylonitrile graft polymerization with cellulose, sodium polyacrylate, hydrolyzate of methyl methacrylic acid and vinyl acetate copolymer , a hydrolyzate of crosslinked polyacrylonitrile, and nonionic superabsorbents include polyvinyl alcohol crosslinked polymers (hereinafter also referred to as PVA-based water absorbers), polyethylene oxide cross-linked Jfiffi polymers (hereinafter also referred to as PEO-based water absorbers) ) etc. are known.

These super absorbent materials are used as admixtures for concrete, cement, etc., as dehydrating materials from organic solvents that do not mix with water, as sanitary materials such as diapers, filter paper, tampons, and napkins.
Seal materials for pure water and ion-containing water, instant sandbags, cold insulation materials, knitted fabrics that lose breathability when wet with rain, curing membranes that take advantage of sliminess during swelling, artificial soil, water blur, filter media, and substitutes for ion exchange resins. Applications to a wide range of applications are being considered. Among these uses, sanitary materials, uses related to ion-containing water, etc. require materials that can absorb a large amount of ion-containing water.

However, most of the superabsorbents that have been reported so far have no effect on water that does not contain ions (e.g. distilled water).
When measured by the tea bag method (referred to as TB method) described below, it shows a very high swelling property of 50 to 1000 times.
In the case of water containing ions such as physiological saline, seawater, aqueous ammonia, and imidacillin salt aqueous solution, the water absorbency is significantly reduced.

Among these super water absorbents, nonionic super absorbents such as PVA water absorbers and PEO water absorbers are exceptional super water absorbers that are not affected by ions. However, PVA-based water absorber, P
Eo water absorbent has low water absorption and TB with immersion time of 24 hours.
The water absorption rate is about 10 to 30 times that of both pure water and seawater, and the water absorption rate is also slow. Most super absorbents other than pvA and PEO water absorbers swell to about 90% of their equilibrium value in a few seconds to minutes in pure water, but PVA and PEO water absorbers have the disadvantage that it takes several hours. .

Carboxymethylated cellulose disclosed in JP-A-52-155218 is known as a cellulose with improved high water absorption with respect to ion-containing water, which has high water absorption and fast water absorption rate. However, it has the disadvantage that it is easily rotted in a swollen state and has low durability under various conditions.

(Problems to be Solved by the Invention) An object of the present invention is to solve the above-mentioned problems and provide a super water absorbent material that has a large amount of water absorption for ion-containing water, has a fast water absorption rate, and has excellent durability. It's about doing.

(Means for Solving the Problems) As a result of various studies to achieve the above object, the present inventors found that by treating an ionic superabsorbent material with a nonionic superabsorbent material, it is possible to reduce the amount of ion-containing water. Biological decay is prevented due to the large amount of water absorption and fast water absorption rate, and the use of an acrylic copolymer as the ionic superabsorbent material and a PEO-based high-handling superabsorbent material as the nonionic superabsorbent material. As a result, they discovered that a super absorbent material with excellent durability could be obtained, and completed the present invention.

That is, the present invention is characterized in that an ionic super absorbent material is treated with a nonionic super absorbent material.

Furthermore, in the present invention, an acrylic super absorbent such as a polyacrylate or a copolymer of an acrylate and acrylonitrile is used as the ionic super absorbent, and a PEo-based high handling By having a water absorbent,
A highly durable superabsorbent material that is resistant to biological decay can be obtained.

The acrylic superabsorbent material, which is an ionic superabsorbent material used in the present invention, can be obtained by a method of hydrolyzing polyacrylonitrile, a method of copolymerizing an acrylic monomer having a carboxyl group, and an active material that can be copolymerized into acrylonitrile and acrylonitrile. It is obtained by copolymerizing monomers that have a double bond and a carboxyl group.

PEO-based high-handling super absorbent material used in the present invention
280, that is, water-soluble polyethylene oxide having an average molecular weight of 100,000 or more,
．． 01 to 5% by weight of mono- and polyisocyanate compounds. The water-soluble polyethylene oxide may have an average molecular weight of 100,000 or more. If the molecular weight is smaller than this range, even similar reaction products will be brittle and will not form a film, will have low swelling properties in water, or will be dispersed in the form of small particles, and will be impractical. In addition, propylene oxide, butylene oxide, and other polymerizable components may be contained as a copolymer to the extent that water solubility is not lost, and within this range, alkylene groups or alkyl groups may be contained in the main chain or side chain. You can leave it there. These may be used alone or in a mixture of two or more. By using these fast copolymers or mixtures, it is also possible to suitably adjust the properties of the resulting resin, such as water swelling properties.

On the other hand, mono- and polyisocyanate compounds are organic compounds containing one or 21 or more isocyanate groups in the same molecule, such as n-propyl isocyanate, n-butyl isocyanate, n-hexyl isocyanate, Dodecyl isocyanate, octadecyl isocyanate, cyclohexyl isocyanate, benzyl isocyanate, phenyl isocyanate, p-chlorophenylisocyanate, p-nitrophenyl isocyanate, 2-chloroethyl isocyanate, stearoyl isocyanate, p-dololsulfonyl Isocyanate, propane diisocyanate, hexane diisocyanate, decane diisocyanate, ω・ω1-dipropyl ether diisocyanate, thiodiethyl diisocyanate, hexafluoropropane diisocyanate, 1
．． 3-dimethylbenzene-ω・ω1-diisocyanate, 1゜4-dimethylnaphthalene-ω・ω1-diisocyanate, 2,4-tolylene diisocyanate, 1.3
-dimethylbenzene-2,4-diisocyanate, naphthalene-1,4 diisocyanate, biphenyl-4,4
1-Diisocyanate, 2-nitrobiphenyl-4,4
'Diisocyanate, 3,3'-dimethoxybiphenyl-4,4f-diisocyanate, diphenylmethane-4
, 4''-diisocyanate, 3,3'-dichlorodiphenyldimethylmethane-4,4f-diisocyanate, 1
-methylbenzene-2,4,6-triisocyanate,
naphthalene-1,3,7-) diisocyanate, biphenyl-2,4,4'-triisocyanate, triphenylmethane-4,4°,4'.

- Triisocyanate, or polyol such as TDI trimer (Desmodur IL), polymethylene polyphenylisocyanate (manufactured by Upjohn), trimethylolpropane, etc., with a molar number corresponding to the number of active hydrogens in the diisocyanate. Examples include urethane triisocyanate compounds (desmodur) obtained by reacting analytes.

Furthermore, these mono- and polyisocyanate compounds may be masked with a suitable masking agent as long as the temperature can be raised above the regeneration temperature during the reaction. Moreover, these can be used alone or in combination of two or more kinds to be subjected to the reaction. The amounts of mono- and polyisocyanate compounds used in the reaction are o, oi, relative to the polyethylene oxide resin.
It is preferably 0.05 to 5% by weight, and usually 0.05 to 2% by weight, although it varies depending on the type of each reaction composition.

The usual method for reacting polyethylene oxide resin with mono- and polyisocyanate compounds is to react them in the form of a solution in a suitable solvent, but it is also possible to react them in the form of a dispersion in a solvent, or to react them in the form of a powder or solid. It is also possible to uniformly mix the two and then heat the reaction to a required temperature. The reaction temperature is generally preferably 50°C to 150°C.

The shape of the acrylic superabsorbent material used in the present invention is powdery,
Acrylic superabsorbent powder, granules, or film are held between and/or on the surface of fibrous structures such as granular, film, or sheet fabrics, nonwoven fabrics, and threads. Things are good.

Whether the fibrous structure is short fiber or long fiber,
Or it may be a combination of these.

As a method for treating an ionic super water absorbent with a nonionic super absorbent, for example, if the ionic super water absorbent is a polymer powder, the nonionic super water absorbent and the ionic super absorbent dissolved in a volatile organic solvent can be used. The water absorbing material of the present invention can be obtained by mixing and stirring the polymer powder, removing the organic solvent by volatilization, and then pulverizing the obtained lumps.

In addition, when the ionic superabsorbent material is a structure such as a film, sheet-like fabric, nonwoven fabric, or thread, it can be soaked in the structure and then squeezed with a mangle; The water-absorbing material of the present invention can be obtained by a method similar to warping with glue, a method using real glue (for example, Unisizer, a trade name of Kaji Seisakusho), or the like.

(Effects of the Invention) The moisture absorbing material of the present invention has a large water absorption amount even for ion-containing water, a fast water absorption rate, and excellent durability.

(Examples) The present invention will be explained in more detail below using examples. All percentages in the examples are percentages by weight.

The evaluation method of characteristic values in Examples is as follows.

Water absorption: a) TB method A sample placed in a polyester net is immersed in 20"C water for a certain period of time, suspended in the air for 10 minutes, and then removed from the net and weighed. A
Then, calculate the water absorption capacity using the following formula.

However, C in the formula is the weight after drying in hot air drying 3 adjusted to 80° C. until there is no change in weight.

CB method The sample whose weight was measured by the TB method is returned to the polyester net and dehydrated for a predetermined time using a centrifugal dehydrator with a force of 100 G. After that, the sample is taken out from the net and its weight is measured. The weight at this time is taken as B, and the water absorption capacity is determined by the following formula.

Example 1 20 parts of polyethylene oxide resin with an average molecular weight of 500,000 and 0.05 part of triethyldiamine were added to 38 parts of nitromethane.
After completely melting at 30 to 40°C in a nitrogen atmosphere, 0.1 part of ■-methylhenzole and 2,5-diisocyanate were added and reacted at 70°C for 5 hours. Water absorption capacity of the obtained PEo-based high-handling superabsorbent film: T
(30x) using method B. 10 parts of this PEO-based water absorbent was mixed and stirred with 45 parts of toluene and 45 parts of ethylene dichloride to obtain a liquid PEO-based high-handling super water absorbent. 100 parts of this liquid PEO-based high-handling superabsorbent material and 10 parts of powdered Aqua Keep 103H (manufactured by Seitetsu Kagaku Kogyo ■, trade name), which is a polyacrylate-based superabsorbent polymer, were thoroughly mixed and stirred, and then evaporated. Allowed to dry. This solid was pulverized to create a powdery superabsorbent material. The absorption performance of the powdered superabsorbent material thus obtained was compared with that of powdered Aqua Keep 103H single form and the above PEO.
Table 1 shows a comparison with the powdered material, which is a high-handling super absorbent material.

As shown in Example 1 in Table 1 below, the product of the present invention has greatly improved absorption capacity for artificial seawater compared to Comparative Examples 1 and 2. Furthermore, it was confirmed that the product of the present invention did not deteriorate even after long-term use.

Example 2 Boester spunbond E5030 (manufactured by Asahi Kasei Kogyo ■, trade name of polyester long fiber nonwoven fabric) coated with acrylic adhesive was coated with powdered Aqua Keep 103H (Steel Chemical Industry Co., Ltd.), which is an ionic super water absorbent. 30 g/m of polyester spunbond E5030 coated with an acrylic adhesive was layered on top of the mold and bonded by applying pressure with a roller.

This sheet-like material was soaked in the toluene/ethylene dichloride-based liquid PEO-based high-handling superabsorbent material of Example 1, and the squeezing rate was 200%.
The liquid was squeezed out using a mangle and dried. Table 2 shows the absorption capacity for artificial seawater of the sheet-like material thus obtained and the sheet-like material before PEO processing.

As shown in Table 2, Example 2, the product of the present invention has greatly improved water absorption capacity for artificial seawater compared to Comparative Example 3.

Claims (2)

[Claims] (1) A moisture-absorbing material characterized by treating an ionic super-absorbent material or a water-absorbing material containing the same with a non-ionic super-absorbent material. (2) the ionic superabsorbent material is an acrylic copolymer,
2. The moisture absorbing material according to claim 1, wherein the nonionic superabsorbent material is a crosslinked polyethylene oxide polymer.