JPH0229798B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a novel method for producing alginate fiber paper. More specifically, the present invention efficiently produces alginate fiber paper, which is composed of short fibers mainly made of alginic acid, water-insoluble alginates, or alginic acid derivatives, and has sufficient strength and good texture and feel. It's about how to do it. Prior Art Alginic acid is a linear polymer consisting of α-(1,4)-L-guluronic acid and β-(1,4)-D-mannuronic acid, and is a type of polysaccharide. It exists widely in nature as the cell membrane and intercellular material of brown algae. Currently, this alginic acid is used as a relatively inexpensive industrial raw material in the food field as an ice cream stabilizer, thickener, emulsion stabilizer, beer foam retention stabilizer, etc., and in the textile field as a spinning paste, printing paste, It is widely used in finishing pastes and as a sizing agent in the paper manufacturing field. On the other hand, alginate alkali salts are known to have stringiness, and long fibers of the calcium salts are currently used as surgical fibers. Also, during World War II, it was woven into a cloth called alginate hessian and used as a substitute for burlap in military camouflage nets. Furthermore, it is known that it can be used as a nonwoven fabric made of long fibers or knitted as a knitted fabric. However, in these sheets, since the single fiber strength of the alginate (calcium) fibers is low, the sheets obtained from the alginate fibers have low strength, and the dry fibers are hard and have no drapability. However, their use is extremely limited. By the way, paper is a sheet obtained by short fibers composed of cellulose forming interfiber bonds through hydrogen bonding, but the number of interfiber bonds is an order of magnitude higher than that of woven fabrics and long fiber nonwoven fabrics. Because of its many differences, it has sufficient strength for practical use even if its single fiber strength is low, and its uses include:
Unlike cloth, drapability is not an issue, and it is used in fields that require something with high rigidity, so-called "stiffness." Therefore,
If paper could be produced from alginate fibers, the above-mentioned drawbacks of the fibers and the woven and nonwoven fabrics obtained therefrom would be eliminated. So far, there have been two attempts to make paper from alginate fibers.
(U.S. Patent No. 2,600,504 and British Patent No. 1,370,888;
No. 35204). However, in the former method, the fibers are treated with an alkali, some of which are treated with a water-soluble alkali salt, and the fibers are fixed together like a binder, since it is not possible to form bonds between fibers even when a wet paper is formed. The obtained paper has a film-like texture,
It is not satisfactory as a paper. In the latter, the gel-like water-insoluble alginate fibers are beaten in the same way as normal pulp, so the fibers are pulverized and treated with water with a pH of 7 or less to form interfiber bonds without a binder. Even if the paper is allowed to dry, the wire gauze is often clogged, the drainage properties are low, and the fibers are too short, making it impossible to form paper with usable strength and texture. Problems to be Solved by the Invention Under these circumstances, the purpose of the present invention is to efficiently produce fibers with sufficient strength and good properties from short fibers mainly made of alginic acid, water-insoluble alginates, or alginic acid derivatives. An object of the present invention is to provide a method for producing alginate fiber paper having a texture and feel. Means for Solving the Problems As a result of extensive research, the present inventors found that by making paper by a wet method using short fibers having a specific fiber diameter and fiber length/fiber diameter ratio, We have discovered that the above object can be achieved, and based on this knowledge, we have completed the present invention. That is, the present invention provides fibers with a diameter that are mainly made of at least one selected from alginic acid, water-insoluble alginates, and alginic acid derivatives.
This invention provides a method for producing alginate fiber paper, which comprises dispersing short fibers of 0.5 mm or less and a fiber length/fiber diameter ratio of 150 or less in water to form paper, and drying the obtained wet paper. be. In the method of the present invention, in order to perform paper making smoothly, the first requirement is to uniformly disperse the short fibers in water without entanglement.
In water, the fibers fully contain water and become gel-like, so they are relatively flexible, and therefore,
If the ratio of fiber length to fiber diameter is not appropriate, the fibers will intertwine and become entangled with each other when dispersed in water, forming bound fibers and failing to form a paper layer. This fiber length/fiber diameter ratio needs to be 150 or less. If this ratio exceeds 150, even if the concentration is extremely diluted, the short fibers become entangled with each other to form fiber bundles, making it impossible to make paper. In addition, when using short fibers with a relatively large ratio within the above range, dispersants commonly used in the production of Japanese paper and chemical fiber paper, such as mucilage obtained from plants such as A.
Paper may be made by adding a synthetic adhesive such as polyethylene oxide or polyacrylamide. On the other hand, when spinning by a wet method, the diameter of the short fibers is selected depending on the wet strength of the fibers, and in the present invention, it is selected within the range of 0.5 mm or less. If the fiber diameter exceeds 0.5 mm, the number of bonds between fibers will be small and paper with good texture and strength will not be formed. In addition, the fiber diameter
Short fibers of 0.5 mm or less have the advantage that they can be sufficiently spun even from fibers with an extremely low degree of polymerization or from fibers containing 50% by weight or less of other polysaccharides. The second requirement is smooth formation of interfiber bonds. In natural pulses made of natural cellulose, cellulose maintains its crystallinity, so hydrogen bonds between fibers are easily formed, but in short rayon fibers, which are regenerated cellulose, the arrangement of cellulose molecules is disordered. Since the hydrogen bonds between the fibers cannot be formed to maintain sufficient strength as paper, a binder is usually used to bond the fibers together. In contrast, in the short fibers used in the present invention, the constituent α-L-guluronic acid and β-D
- Since the mannuronic acids are arranged very orderly, i.e. axial-axial when α-L-gloronic acid forms a block polymer, β-D-mannuronic acid forms a block polymer. In some cases, the bond is equatorial-equatorial, and the bond between α-L-guluronic acid and β-D-mannuronic acid is an axial-equatorial bond, so it is formed simply by wet spinning. Even with wet paper, if the wet paper is sufficiently pressed and dried, it can be welded without a binder or by treating the wet paper with an alkaline water-soluble solution such as caustic alkali or its carbonate to make some of it water-soluble and weld it. Even without using any other means, dense interfiber hydrogen bonds are formed that can maintain sufficient strength as paper. However, since the strength of the main fibers is not very high when fine fibers are mixed in, the strength of the paper is significantly reduced, so it is necessary to make the fiber lengths uniform within a range that does not hinder dispersion. In this point,
This fiber is significantly different from cellulose pulp, other compound fibers, or synthetic pulp, and beating etc. must be absolutely avoided. The third requirement is to dry the wet paper so that wrinkles do not form on the dry paper. The short fibers used in the present invention exhibit a gel-like state in a wet state and have a higher moisture content than cellulose or the like, so when drying wet paper, they shrink significantly and tend to wrinkle when dried. Therefore, when drying a wet paper, it is desirable to apply pressure or tension or both to the wet paper while drying the paper slowly to avoid moisture removal due to rapid heating. By making paper so as to satisfy the above requirements, alginate fiber paper with strength and good texture similar to Japanese paper or rayon paper can be obtained. The short fibers used in the present invention are mainly composed of at least one selected from alginic acid, water-insoluble alginates, and alginic acid derivatives. Water-insoluble alginates include calcium, barium, iron, and
Alginic acid derivatives include those made by grafting alginic acid with alkylene oxide or treating it with diisocyanate or dialdehyde to make it insolubilized.
Examples include those that are difficult to shrink. In the method of the present invention, single fibers composed of these compounds may be slightly hard when dried, and in that case, other polysaccharides are added to improve spinnability when wet spinning the fibers. It is preferable to include it in the compound to the extent that it does not interfere. Examples of the polysaccharide include acidic heteroglycans such as κ-carrageenan, λ-carrageenan, i-carrageenan, and xanthan gum; glucuronans such as pectin;
Examples include acidic mucopolysaccharides such as hyaluronic acid and chondroitin sulfate. By adding such polysaccharides, the physical properties of the spun short fibers are improved, and for example, in order to obtain alginate fiber paper with immobilized enzymes and microorganisms, the fibers are dispersed in water and formed. When enclosing enzymes and microorganisms in a gel-like material, their retention, action, growth, etc. can be optimized. Effects of the Invention The alginate fiber paper obtained by the method of the present invention has sufficient strength for practical use. Examples include medical gauze that utilizes anti-inflammatory properties.
Next, since the fiber paper is porous and has an extremely high specific surface area compared to beads, woven fabrics, knitted fabrics, etc., it has excellent properties by enclosing enzymes and microorganisms in the gel fibers. It can be made into a fiber paper that has the function of a bioreactor, and it can also be made into a medical test paper by incorporating various diagnostic reagents into the gel fiber. Examples Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 A 4.0% by weight (air-dried) aqueous solution (viscosity of a 1% by weight aqueous solution at 20°C: 650 to 750 cp) of sodium alginate [manufactured by Kimitsu Chemical Co., Ltd., type H] was filtered using a pressure filtration machine (manufactured by Toyo Kagaku Sangyo, KST293). −3ST),
After filtering through filter paper No. 60 (manufactured by Toyo Kagaku Sangyo), using a wet spinning machine, the spinning speed was 13.5ml/
The fibers of calcium alginate were obtained by spinning from a 1000-hole spindle with a diameter of 0.1 mm at 100 min, using a coagulation bath of a 5% by weight calcium chloride aqueous solution. This fiber was cut into a fiber length of 3 mm using a guillotine cutter (manufactured by Onochi Seisakusho Co., Ltd.). The fiber diameter of this material is 0.1 mm, and the fiber length/fiber diameter ratio is 30. Furthermore, the bundled fibers were separated and removed by passing through a flat screen with a slit width of 6/1000 inch. When these short fibers were dispersed with a standard disintegrator after adding water to the normal paper-making density, no binding of the fibers was observed. However, with a fiber length of 5 mm,
In the case where the fiber length/fiber diameter ratio was 50, some of the fibers were entangled with each other to form bound fibers, and in the case where the fiber length was 15.5 mm and the fiber length/fiber diameter ratio was 155, a complete fiber mass was formed. The short fibers have relatively good dispersibility in water, but if left undisturbed, they become flocculent and it is difficult to obtain paper with a uniform texture. The short fibers were dispersed and made into paper using a TAPPI standard sheet machine at a fiber concentration such that the basis weight was approximately 60 g/m ² . Next, the paper was thoroughly pressed to remove as much moisture as possible, and then air-dried under a press to obtain a wrinkle-free calcium alginate fiber paper with a basis weight of 68.2 g/m ² . Regarding the strength of this thing, the tearing length is 3.56
Km, specific tear strength was 59, and folding strength was 53. This fiber paper had an extremely good texture similar to rayon paper, and the feel was almost the same as that of Japanese paper. For comparison, when the wet paper after pressing was dried at 80°C without being pressed, the dry paper shrunk significantly and many wrinkles appeared. Also under press 50
When dried at a temperature below 0.9°C, no wrinkles appeared at all. Example 2 The calcium alginate fiber obtained by wet spinning in Example 1 was immersed twice in 9% hydrochloric acid for 10 minutes at room temperature, washed with water, and the same operation was repeated to remove Ca and H. Free alginate fibers were obtained by ion exchange with ⁺ . This fiber was cut into a fiber length of 3.0 mm in the same manner as in Example 1.
Fiber lumps were removed using a flat screen (6/1000 inch). The fiber length/fiber diameter ratio of this short fiber is 30, and the fiber concentration is 1.5 in a standard disintegrator.
Even when dispersed in water at % by weight, no fiber binding due to entanglement of fibers was observed. However, when the fiber length is 5.0 mm and the fiber length/fiber diameter ratio is 50,
Some fibers were crossed during dispersion, and the fiber length was 15.5.
mm, and a fiber length/fiber diameter ratio of 155, the fibers were completely entangled and could not be dispersed. Although these free alginate fibers have higher dispersibility in water than the corresponding calcium salt fibers, they still tend to aggregate, so it is better to make paper by adding 2% by weight of polyethylene oxide as a sticky agent.
The ground was even better. Wet paper shrinks significantly when drying and tends to wrinkle, so apply a pressure of 3.5 kg/
A dry paper was obtained by drying at room temperature under a cm ² press. Drying under such pressure resulted in no shrinkage wrinkles. The obtained alginate fiber had high transparency (opacity 41.0%) and flexibility, and its strength was 3.34 km in tear length, 44 in specific tear strength, and 33 in folding strength. The condition was also extremely good. Examples 3 to 6 According to Examples 1 and 2, two types of sodium alginate with a low degree of polymerization [manufactured by Kimitsu Chemical Co., Ltd., type
IL-2 (viscosity of 1% aqueous solution at 20°C: 30~
50 cp), Type I-3 (viscosity of 1% by weight aqueous solution at 20°C: 320 to 380 cp)]. Since these raw materials have extremely low viscosity, a 5.0% by weight (air-dried) aqueous solution was used for spinning to form calcium alginate fibers for convenience of filtration. As a result, when the fiber length/fiber diameter ratio was 30, no fiber bundling was observed, at 50, some fiber bundling occurred, and at 155, the fibers were intertwined and not dispersed at all.
Table 1 shows the properties of the obtained alginic acid and calcium alginate fiber paper.

[Table] Example 7 Using sodium alginate (manufactured by Kimitsu Kagaku Co., Ltd., type H), fibers were spun from a 1000-hole spindle with a diameter of 0.055 mm at a concentration of 3% by weight according to Example 1. Calcium alginate fibers with a diameter of 0.05 mm were obtained. This fiber has a fiber length of 3 mm (fiber length/fiber diameter ratio 60),
It was cut into 5mm (120mm) and 8mm (160mm). Next, the fiber bundles were removed using a flat screen with a slit width of 6/1000 inch, and then the fiber concentration was reduced using a standard disintegrator according to Example 1.
The dispersibility was evaluated by dispersing to a concentration of 1.5% by weight. The fiber lengths of 3 mm and 5 mm had extremely good dispersibility, but the fibers of 8 mm were intertwined with each other to form a fiber mass. A paper having a fiber length of 3 mm was made according to Example 1, and a paper which was treated with hydrochloric acid at the fiber stage to form free alginic acid was also made in the same manner. The results are shown in Table 2.

[Table] Examples 8 and 9 κ for sodium alginate (type H)
- carrageenan or pectin at a weight ratio of sodium alginate/κ-carrageenan or pectin of 3/1
A mixture of the following was used. A 3% by weight aqueous solution of this mixture was prepared and spun according to Example 1 to obtain calcium alginate fibers containing κ-carrageenan or pectin. In addition, a part of it will be 9%
The free acid form was obtained by soaking twice in hydrochloric acid for 10 minutes. These were paper-made according to Example 1 to obtain other polysaccharide-containing alginate fiber paper. All of the obtained fiber papers had a good Japanese paper-like appearance. Their physical properties are shown in Table 3.

[Table] Examples 10, 11 Using sodium alginate (type H),
According to Example 1, barium alginate fibers and aluminum alginate fibers were obtained using coagulation solutions of a 5% by weight barium chloride aqueous solution and a 5% by weight aqueous aluminum chloride solution, respectively. Corresponding fiber papers were then made from each short fiber (fiber length 3 mm). Their physical properties are shown in Table 4.

【table】

Claims (1)

[Scope of Claims] 1. Short fibers mainly composed of at least one selected from alginic acid, water-insoluble alginates, and alginic acid derivatives, with a fiber diameter of 0.5 mm or less and a fiber length/fiber diameter ratio of 150 or less. A method for producing alginate fiber paper, which comprises dispersing fibers in water and forming the paper, and then drying the obtained wet paper to form bonds between the fibers to form a sheet. 2. The production method according to claim 1, wherein the short fibers contain 50% by weight or less of other polysaccharides. 3. The manufacturing method according to claim 1, in which a sticky agent is used in combination when dispersing the short fibers in water. 4. The manufacturing method according to claim 1, wherein the wet paper is dried while applying pressure or tension or both to the wet paper.