JPH04146902A - Fibrous, highly water-absorptive cellulosic substance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cellulose material that has high water absorption capacity while maintaining the fiber shape of cellulose #I fibers as a starting material.

[Conventional technology]

Super absorbent polymers are structurally water-soluble polymers that are slightly three-dimensionally crosslinked to make them insoluble in water, and quickly absorb water to form a gel. Taking advantage of its amazing ability to absorb water, it is increasingly being applied to sanitary products such as disposable diapers and sanitary napkins.

Various types of super absorbent polymers are known, mainly cross-linked polyacrylates, which have superior water absorption and retention capabilities compared to conventional water absorbing materials (absorbent cotton, pulp, etc.). have. However, the drawbacks are: ■ Absorption capacity for urine, saline, etc. is significantly reduced;
■Since the product is in powder form, when making applied products,
There are some problems based on the shape of the product, such as the need for some kind of support, and (1) the need for the powder to be uniformly dispersed in the support, which sometimes causes the powder to fall off the support.

In order to overcome these drawbacks, various improvements have been made, and one possible method is to change the conventional powder polymer into a fibrous form and take advantage of the advantages of MA fibers.

In general, such cellulose-based [M] absorbers are
Cross-linked CMC (carboxymethylcellulose), hydrolysates of cellulose-polyacrylonitrile graft copolymers, cellulose-polyacrylic acid graft copolymers, etc. are already known, but none of these, except for cross-linked CMC, have been put into practical use. It has not been.

Commercially available polyacrylic acid-based superabsorbent polymers have a high water absorption capacity, and usually have a pure water absorption of 100μ1/g or more (
Tea bag method, non-pressurized 10 minute value, details of measured values will be described later>, and artificial urine absorption amount of 30 m1/g
It has an absorption capacity of (10 minute value using tea bag method).

However, the absorption capacity of cellulose-based fiber absorbers such as the hydrolyzate of the cellulose polyacrylonitrile graft copolymer described above is extremely poor.

[Problem to be solved by the invention]

The present invention has an excellent ability to absorb water and artificial urine, and ml! The purpose is to obtain a highly water-absorbent cellulose-containing material having a #-like shape.

[Means to solve the problem]

The fibrous superabsorbent cellulose material of the present invention is produced by adding an alkali hydroxide to a fibrous cellulose-containing material in the presence of a water-containing organic solvent containing an alkali hydroxide, and a carbon number of 1 to 3 and at least A fibrous material obtained by reacting one halogen group or epoxy group with an etherifying agent having at least one sulfonic acid group to form a water-soluble cellulose derivative containing a sulfonic acid group, and then crosslinking the resulting water-soluble cellulose derivative. The present invention relates to a highly absorbent cellulose-containing material.

The reason why cellulose derivative-based fiber absorbers have inferior water absorption ability compared to commercially available superabsorbent polymers is that the cohesive force based on water-purple bonds between cellulose molecules suppresses swelling, and the number of hydrophilic groups It is estimated that the dissociation ability in water is insufficient. Although the detailed mechanism by which water absorption is significantly improved by performing an etherification reaction to introduce the above-mentioned sulfonic acid groups into cellulose is unknown,
The etherification reaction that introduces sulfonic acid groups destroys the crystal structure of cellulose and promotes swelling.
It is presumed that the effect of introducing a functional group (sulfonic acid group) with a high affinity for water contributes.

In addition, the resulting cellulose containing sulfonic acid groups is generally soluble in water, and moderate crosslinking increases absorption capacity and improves absorption rate and other properties. This is known from absorbent polymers. In addition to thermal crosslinking, common chemical crosslinking agents such as epichlorohydrin and ethylene glycol diglycidyl ether can be used as the crosslinking method.

As the cellulose-containing substance used in the present invention, any fibrous #@-like cellulose such as pulp, cotton cloth, rayon, paper, etc. can be used, but wood bulbs are particularly suitable because they are inexpensive and can be obtained from scales. .

Next, the etherification reaction for introducing a sulfonic acid group into the cellulose material is carried out using an alkali hydroxide and at least one halogen group or epoxy group having 1 to 3 carbon atoms in the presence of a water-containing organic solvent. at least one sulfone 1
! This can be carried out by reacting an etherification agent having 82 groups.

Specifically, the etherification agent includes sodium chloromethane sulfonate, sodium bromomethane sulfonate,
- Sodium chloro-2-hydroxyethanesulfonate,
Sodium 2-bromo-1-hydroxyethanesulfonate, sodium 1,2-uboxyethanesulfonate, sodium 2-chloroethanesulfonate, sodium 3-chloropropanesulfonate, sodium 3-chloropropanesulfonate, Sodium 3-chloro-2-hydroxypropanesulfonate, sodium 2.3 eboxybrobanesulfonate, etc. can be used.

As the water-containing organic solvent, a mixture of alcohol and water such as methanol, ethanol, propatool, butanol, and pentanol can be used, but propatool and butanol are particularly preferred because of their high reaction efficiency. As the alkali hydroxide, sodium hydroxide, potassium hydroxide, and lithium hydroxide can be used.

As mentioned above, the etherification is performed to reduce the crystallinity of the cellulose, develop swelling power, and obtain the desired amount of water absorption. It is important to control the reaction to an appropriate degree of reaction (usually the degree of substitution of cellulose). As mentioned above, various methods can be applied to the etherification reaction to introduce the sulfonic acid group, but if the reaction conditions are too harsh, the degree of polymerization will decrease due to cellulose decomposition, and the fiber length will become short. On the other hand, if the conditions are relaxed and the degree of reaction (degree of substitution) is too small, sufficient absorption capacity will not be obtained. Therefore, the appropriate reaction temperature,
It is necessary to control the reaction temperature by selecting the reaction solvent. Usually, it is preferable to reduce 111 degrees to 0.1 to 10 by an etherification reaction to introduce a sulfonic acid group.

The above reaction product is washed with a mixed solvent of water and alcohol, then dried and pulverized to obtain a product.

Examples will be specifically described below, but the present invention is not limited thereto.

Examples] 1) Etherification with sodium chloromethane sulfonate 30 g of NaOH in a 500 ml flask (addition rate 300
%) and add 25 ml of water to dissolve it.

To this, add 200ml of n-butanol, Bulb], Og(
BD), stir well, and leave at room temperature for 1 hour to perform mercerization. Next, sodium chloromethane sulfonate 9
．． Add 4g (1!94% addition) and mix well for 30 minutes. Attach a reflux condenser and heat in a 120°C oil bath for 3 hours. Reaction materials completed, contents reduced to 75% methanol 8
00ml, filtered with a glass filter. The filtrate is washed with 75% methanol until it no longer turns red due to phenolphthalein, and after substitution with methanol, it is dried in a vacuum v, ftR oven at 40°C (degree of substitution 053).

2) Crosslinking of etherified pulp 58.2 ml of isopropanol in a 100 ml flask,
Take 11.0 ml of water and add 8 ml of epichlorohydrin isopropanol solution at a temperature of 50 g/l (addition rate 3%).
), 0.97 ml of NaOH aqueous solution with a concentration of 40 g/l (
1.3%) and then add the above derivative. Attach a reflux condenser and heat under reflux in a 90°C oil bath for 1 hour. Wash with 80% methanol, reflux with methanol, and dry in a vacuum dryer at 40°C.

3) Measurement of pure water absorption amount and artificial urine absorption amount・Pure water・Composition of water distilled after ion exchange・Artificial urine (wt%) Deionized water 97.09 Urine chart 2.0ONaC
10,80 Mg5○4.7H200,08 CaC12,2H200,03 Put the specified 1i (0,1~Ig) into a 250 mesh nylon wire teabag, and add 11g of pure water or artificial urine.
Absorb the liquid for 0 minutes. Thereafter, the tea bag was removed from the liquid, drained for 10 minutes, and the amount of liquid absorbed per unit weight of the sample was calculated.

The results are shown in Table 1.

Example 2 Etherification with sodium 3-chloro-2-hydroxypropanesulfonate 3 g of pulp (BD) was placed in a 200 ml flask, and a mixture of 60 ml of isopropanol and 6 ml of water was added.

3. Add 1.48 g of NaOH (addition: 1!49%), stir well, and leave to stand at room temperature for 1 hour to mercerize sodium 63-chloro-2-hydroxypropanesulfonate.3.
Add 64g (addition rate 121%) and mix well for 30 minutes. Attach a reflux condenser and heat in a 70°C water bath for 15 hours. After the reaction was completed, the contents were poured into 200 ml of 75% methanol, thoroughly washed with water, and filtered through a glass filter. Wash with 75% methanol until phenolphthalein no longer turns red, replace with methanol, and dry in a vacuum dryer at 40°C. The cellulose derivative obtained here was subjected to the above-mentioned etherification once more to obtain a water-soluble derivative, which was then crosslinked with epichlorohydrin in the same manner as in Example 1 to obtain a JliiM-like product.

Example 3 Etherification with sodium 2.3-epoxypropanesulfonate 2.96 g of sodium 2.3-epoxypropanesulfonate was used in place of the sodium 3-chloro-2-hydroxypropanesulfonate using the method of Example 2. The same procedure was carried out except that the reaction time was changed to 6 hours.

Example 4 Etherification with sodium 1-chloro-2-hydroxy-ethanesulfonate Sodium 1-chloro-2-hydroxy-ethanesulfonate was used in place of the sodium 3-chloro-2-hydroxypropanesulfonate in the method of Example 2. The same procedure was carried out except that 3.37 g of the sample was used.

Comparative Example 1 As a control, the average values of three types of commercially available superabsorbent polymers such as sodium polyacrylate and starch-based commercially available polymers obtained by graft polymerization of sodium polyacrylate are shown in Table 1.
This is shown in the comparative example.

Table 1 [Effects of the Invention] According to the present invention, it is possible to provide a highly water-absorbing cellulose-containing material that maintains the original M&fiber shape of the cellulose raw material and has excellent water absorption ability. The fibrous material of the present invention exhibits excellent absorption capacity for water, salt solutions, urine, blood, etc., is inexpensive, has excellent processability, and uses cellulose as the main raw material. Therefore, it has excellent biodegradability and can be used in various applications such as disposable diapers, sanitary products, soil water retention materials, and dew condensation prevention shrines in interior building materials.

Patent applicant: Oji Paper Co., Ltd.

Claims (1)

[Claims] In the presence of a water-containing organic solvent containing alkali hydroxide, a fibrous cellulose material, a carbon number of 1 to 3 and at least one halogen group or epoxy group, and at least one
A fibrous superabsorbent cellulose material characterized by reacting with an etherification agent having sulfonic acid groups to produce a water-soluble cellulose derivative containing sulfonic acid groups and crosslinking the resulting water-soluble cellulose derivative.