JPH01164436A - Highly water-absorptive base material to be used in aqueous solution of electrolyte - Google Patents

Abstract

PURPOSE:To improve a coefft. of absorption for aq. soln. of an electrolyte of a highly water-absorptive base material by allowing the highly water- absorptive base material to contain or to be deposited with a builder or ion exchange resin, etc., having ion sequestering property in its inside or on its surface. CONSTITUTION:A highly water-absorptive base material for absorbing aq. soln. of an electrolyte to be used for preventing permeation of water, etc., such as paper diaper, physiological napkin, etc., is produced by forming an upper layer, a lower layer, and a middle layer 1, 2, 3 comprising a mixture of an appropriate proportion of highly water-absorptive fiber and low melting polyester fiber formed integrally with a heating roll. A builder 4 such as sodium tripolyphosphate, etc., is scattered on the highly water-absorptive nonwoven cloth or impregnated into the nonwoven cloth, and the cloth is dried with hot air. Or, the highly water-absorptive base material is produced by incorporating uniformly an ion exchange resin 5 (e.g., cation exchange resin 5B, anion exchange resin 5A) into the fiber layer for the middle layer 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the improvement of superabsorbent base materials for discharging electrolyte water-soluble iCC used for preventing water running in disposable diapers, sanitary napkins, submarine cables, etc. be.

[Conventional technology and its problems]

Super absorbent materials such as super absorbent resins and super absorbent fibers currently used in many fields such as disposable diapers and sanitary napkins generally absorb 500 g to 100 g of pure water per gram. However, in electrolyte aqueous solutions such as blood and seawater, the water absorption rate is reduced to about 1/10 to 1/20 of that of pure water. That is, in physiological saline (0.9% NaCβ aqueous solution), it is 50-8
It stops absorbing water at 0g. Because of this, electrolyte water 78i
Regarding the water absorption of α, the ′i! of highly absorbent materials such as super absorbent resins and super absorbent fibers There is a problem that it is difficult to estimate the exact usage amount, and the usage amount inevitably increases. In particular, this tendency is most remarkable in the case of sodium acrylate vehicle combination, which is a typical super absorbent resin.

[Means for solving problems]

The present invention solves the above-mentioned problems by adding a builder having an ion-sequestering property or a substance having an ion-exchange ability to a superabsorbent material in an amount of 5 to 150 tonne inside the superabsorbent material. Alternatively, the above problems can be solved by containing or adhering it to the surface. In other words, the reason why superabsorbent resins such as superabsorbent materials such as sodium acrylate polymer, vinyl alcohol acrylate copolymer, and polyethylene oxide modified products exhibit high water absorption ability is due to the carboxyl groups attached to the polymer chains. Due to the attractive force of negative charges, the concentration of mobile ions such as sodium and potassium cations is higher than that of super absorbent resins! ! Osmotic pressure occurs because it is always higher inside than 1,
It is also due to the II f loca of polymer electrolyte and water.

However, if the electrolyte concentration in the electrolyte aqueous solution is high, the osmotic pressure will be low and the affinity of the polymer electrolyte will also be low, so the water absorption ability of the superabsorbent resin will be reduced in the electrolyte-containing aqueous solution. Therefore, in the present invention, when contacting and absorbing this electrolyte aqueous solution into a superabsorbent resin, builders having ion-sequestering properties such as sodium tripolyphosphate, sodium birophosphate, sodium hexametaphosphate, potassium birophosphate, sodium silicate, EDTA (ethylenediamine 4 By using sodium acetate (disodium acetate), etc., a complex compound is formed by association or covalent bonding with metal ions such as calcium ions, magnesium ions, iron ions, etc. in water, and the water absorption of super absorbent materials is achieved by sequestering metal ions. Electrolyte water can be improved by preventing a decrease in capacity, by using both a strongly acidic cation exchange resin and a basic anion exchange resin as substances with ion exchange ability, or by adsorbing and separating metal ions with synthetic zeolite. The water absorption performance of the super absorbent material in liquid No. 28 has been improved.

[Effect]

When a builder is present near the superabsorbent resin, the metal ions in the electrolyte aqueous solution, which become water-absorbing astringents, first form a complex with, for example, tripolyphosphate, which is used as a builder, through association or covalent bonding. Water is quickly absorbed by the superabsorbent resin due to the suction force exhibited by the negative charge of the carboxyl group attached to the polymer top of the superabsorbent resin. That is, metal ions such as Ca, Mg, and Fe in the electrolytic U aqueous solution are complexed by the metal ion sequestering property of the builder, and the builder has a buffering effect, reducing the effect of electrolyte ions and reducing the water absorption rate. It will be improved.

〔Example〕

One embodiment of the present invention will be described in detail below.

[Example 1] FIG. 1 is a schematic cross-sectional view of the superabsorbent base material according to the present invention, which is composed of three layers: upper, middle, and lower. Upper layer 1 and lower layer 2 are made of superabsorbent fibers (registered trademark). Lanseal F (manufactured by Nippon Exlan Kogyo) 7 denier The middle layer 3 is made of water-absorbing fiber IT (registered trademark Lanseal F, manufactured by Nippon Exlan Kogyo), 7 denier x 51 mm; 95%, and a parallel fabric with a basis weight of 60 g/m2, consisting of a mixture ratio of low melting point polyester fiber 4 denier x 51 mm; 5%. Or a cross web with a fabric weight of 80 g/m2, glued together with a heating roll,
It is a super absorbent nonwoven fabric with a thickness of 0.4 m.

1 of sodium tripolyphosphate as a builder to the above nonwoven fabric.
A superabsorbent base material A is prepared by spraying or impregnating with a 0% aqueous solution and drying with hot air to adhere builder 4 to the surface.

A water absorption test was conducted using this super absorbent base material according to the following test method. Further, as a comparative example, a similar comparative test was conducted using water absorbent nonwoven fabric B, which has the same structure as the above-mentioned super absorbent nonwoven fabric and does not contain a builder.

Test method i1: After immersing a 10c+s square sample in a 1% sodium chloride aqueous solution for 10 minutes, hang it by holding one corner of the square and drain for 1 minute. Measure bt increase rate and thickness increase rate.

As shown in Figure 2, the results of the water absorption test show that the superabsorbent base material A of the present invention has an improved water absorption rate compared to the water absorbent nonwoven fabric that does not contain Tf of the builder (sodium tripolyphosphate), and has a sodium tripolyphosphate concentration of approximately 23 g. /m2, reaching a peak at about 50
% water absorption improved.

[Example 2] A predetermined amount of super absorbent resin Sumikagel N-100 (sodium acrylate polymer manufactured by Sumitomo Chemical) and powdered builder (sodium tripolyphosphate) are taken and mixed uniformly to form highly hydrophilic or super absorbent fibers. A highly water-absorbent base material A@- is constructed by enclosing it between layers of a nonwoven fabric using.

This super absorbent base material was soaked in a 1% sodium chloride aqueous solution for 10 minutes? ! After soaking, the samples were hung for 1 minute to measure water drainage and weight increase rate. As shown in FIG. 3, the results show that the super-absorbent base material A of the present invention has improved water absorption compared to the super-absorbent resin B.
The superposition ratio (z) of sodium tripolyphosphate to the superabsorbent resin reached a peak at about 50%, and the water absorption rate improved.

[Example 3] In a nonwoven fabric constructed in the same manner as in Example 1, as shown in FIG. 4, Duolite C-20 (cation exchange resin 5B; manufactured by Sumitomo Chemical) or the cation exchange resin and Duolite A-10
10 (111 ion exchange resin 5A; manufactured by Sumitomo Chemical) was uniformly filled and distributed between the fibers, and the mesh formed integrally with a hot roll was 80 g/B2 or more, and only cation exchange resin with a l width of 0 and 4 mm was mixed. Highly absorbent base material A and cation exchange 1! (A superabsorbent base material Ai was prepared in which fat and anion exchange resin were mixed in a ratio of 1:2.

A water absorption test was conducted on the highly water absorbent base material in the same manner as in Example 1, and the results are shown in FIG.

As shown in the figure, the super absorbent base materials A L and A a of the present invention
The fiber structure of the super absorbent nonwoven fabric was the same as that of the above-mentioned super absorbent nonwoven fabric, and it was found that the water absorption rate increased as the number of machines used by the builder increased compared to Comparative Example B, which did not contain fat.

[Actual case 1 row 4] In the same way as in [Implemented] (using I+, 11 layers of sodium tripolyphosphate were applied in the same manner as above) to form a highly water-absorbent substrate A.
After that, artificially prepared water (shah trademark aquamarine =
A water absorption test of Heshu medicine (+Wa) was conducted in the same manner.

The results of the water absorption test are shown in Figure 6. Comparing the water absorption rates of artificial seawater between superabsorbent base material A to which sodium tripolyphosphate was attached and untreated nonwoven fabric B in the sixth step, the water absorption rate of superabsorbent base material A was improved, and the amount of tripolyphosphate was approximately 100
g/m2, an improvement of approximately 140%.

〔Effect of the invention〕

As described above, according to the present invention, by containing and adhering a builder having ion-sequestering properties or an ion exchange resin, etc. to the super absorbent material, the water absorption rate of electrolyte water waves of the super absorbent material can be increased from 11,320% to 11,320%. It became possible to improve it by 70%. Therefore, it is possible to reduce the absolute amount of highly absorbent materials used in disposable diapers, sanitary napkins, incontinence absorbent pads, submarine cables, etc., and this invention has the effect of improving water absorption capacity.

[Brief explanation of the drawing]

FIG. 1 and FIG. 4 respectively show one example of a super absorbent base material according to the present invention.
A schematic cross-sectional view showing an example, and FIGS. 2, 3, 5, and 6 are curve diagrams showing measured values of water absorption of the present invention and a comparative example, respectively. 1... Upper layer 2... Lower layer 3... Middle layer 4... Builder (tripolyphosphate node) 5A...
・Anion exchange resin 5B...Cation exchange resin Figure 1 Figure 2

Claims (4)

[Claims] (1) A highly water-absorbent base material for an electrolyte aqueous solution, characterized in that a builder having an ion-sequestering property or a substance having an ion-exchange ability is contained and adhered to the interior or surface of the super-absorbent material. (2) A superabsorbent base material for an electrolyte aqueous solution according to claim 1, which uses a superabsorbent resin, a superabsorbent fiber, or a nonwoven fabric made of a superabsorbent or highly hydrophilic fiber as the superabsorbent material. . (3) The highly water-absorbent base material for an electrolyte aqueous solution according to claim 1, which uses a phosphate, a silicate, EDTA, or sodium tripolyphosphate as a builder. (4) The substance with ion exchange ability is an ion exchange resin,
The highly water-absorbent base material for an electrolyte aqueous solution according to claim 1, which is a zeolite.