JP2548093B2 - A method for producing a fiber sheet containing water-soluble seaweed-based polysaccharide as a main component and having excellent water resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a fiber sheet containing a water-soluble seaweed-based polysaccharide as a main component, and more specifically, water resistance containing a water-soluble seaweed-based polysaccharide as a main component. The present invention relates to a method for producing a fiber sheet having excellent properties without using a means harmful to an enzyme or a living body.

[Prior Art] Fibers formed by insolubilizing water-soluble seaweed polysaccharides, particularly fibers made of alginic acid (salt), have been known for a long time, and an aqueous solution of sodium alginate is used as a water-soluble salt of a polyvalent metal such as calcium. A water-insoluble alginic acid fiber is obtained by spinning in the solution. (Large Organic Chemistry, Volume 20, 228-229, published in 1959). Further, alginic acid paper is obtained by forming an interfiber bond by treating the insoluble fiber before or after papermaking with an aqueous solution of an alkali salt to partially solubilize it (USP 2,60).
0,504).

These alginic acid fibers or fiber sheets have large moisture absorption and water absorption, and therefore curls and twists occur when they are rapidly dried. It is known that there are drawbacks such as low tensile strength and elastic modulus when dried, remarkably low tensile strength when wet, and low brittleness. (Kobayashi: Protein, nucleic acid, enzyme; 31 (11) 1066-1077).

On the other hand, water-soluble seaweed-type polysaccharides have been practically used as a culture substrate for microorganisms and a carrier for immobilized enzymes by utilizing their properties of water solubility, gel-forming ability, and nontoxicity to enzymes and living bodies.

Recently, a biocompatible wound dressing material of a fiber or a fiber sheet composed of a water-soluble seaweed polysaccharide, particularly alginic acid,
Attention has been focused on its use as a new functional material such as an enzyme or microorganism immobilization carrier, and further as a biosensor or biochip. (For example, Kobayashi: Chemistry and Industry 39 (7) 521-5
23, proteins, nucleic acids, enzymes 31 (11) 1066 to 1077, etc.).

In these new fields of application, the alginic acid fibers or fiber sheets are made water resistant without the use of enzymes or harmful means to the living body-improvement of water insolubility, improvement of wet strength or interfiber bond when wet. Improvement,
That is, improvement in wet strength is strongly demanded.

Conventionally, as a method of insolubilizing the alginic acid fiber itself, a method of forming an insoluble salt by treating with an aqueous solution containing a polyvalent metal ion such as calcium is known, but strengthening the interfiber bond in the alginic acid fiber sheet. Nobody knows how.

Generally, a method for making a water-soluble polymer water-resistant includes a chemical method such as a method of introducing a crosslinkable functional group into the polymer, a method of using a cross-linking agent suitable for the polymer, and heat treatment, radiation treatment, Many methods such as physical methods such as surface treatment with a hydrophobic substance are known.

[Problems to be Solved by the Invention] However, when the above-mentioned polyvalent metal salts are used for making alginate fibers water resistant, it is difficult to balance water insolubility and mechanical properties, and it is difficult to coordinate metal ions. Has the basic problem of being limited. That is, if the content of the polyvalent metal ion is increased to improve water insolubility,
In particular, the fibers themselves in the dry state become hard and brittle, and the mechanical properties are deteriorated, and at the same time, the interfiber bondability is deteriorated, and the wet strength of the sheet may be decreased. Furthermore, the fibers or the fiber sheet after drying may be markedly colored or may become opaque, and the toxicity to the enzyme or the living body may become a problem depending on the type of metal.

Further, it is not easy to introduce a functional group having a crosslinkability, which is known as a water-resistant method for general water-soluble polymers, into alginic acid or the like in advance without impairing the water-solubility or processability, or even temporarily. Even if it is possible, there is a drawback that it thickens or gels with time and impairs processability.On the other hand, when a method of forming a fiber or a fiber sheet with a cross-linking agent and then making it water resistant is used, it is special for cross-linking. There is a problem that a catalyst or heat treatment is required, and these cross-linking agents, catalysts, and heat treatments are often harmful to enzymes and living bodies.

An object of the present invention is to provide a method for producing a highly water-resistant fiber sheet containing a water-soluble seaweed-based polysaccharide as a main component, without using any means harmful to enzymes or living bodies. Another object of the invention is to provide a fiber sheet containing an enzyme or a microorganism and having excellent water resistance or a fiber sheet harmless to a living body.

[Means for Solving Problems] As a result of intensive studies to achieve the above-mentioned object, the present inventors have blended a water-soluble seaweed-based polysaccharide with a water-soluble acetoacetylated polyvinyl alcohol-based resin. After molding the composition obtained in the form of a fiber sheet, a fiber sheet having excellent water resistance can be obtained by simply dehydrating and drying, and actinic ray treatment is performed prior to dehydration drying or in the process of dehydration drying. Therefore, it was found that the water resistance effect, particularly the effect of improving the interfiber bond strength, can be more easily obtained.
The present invention has been completed.

[Action] The water-soluble seaweed polysaccharides in the present invention are alginic acid and its water-soluble salts, agar, carrageenan, and a mixture of two or more kinds thereof.

Among these, alginic acid (salt) is particularly useful because it has excellent fiber-forming properties.

The water-soluble acetoacetylated polyvinyl alcohol-based resin in the present invention is, for example, JP-B-57-45761.
It is produced by the method described in JP-A-55-137107, but it is not limited to these methods, and for example, by transesterifying a water-soluble polyvinyl alcohol resin with acetoacetic acid esters. can get.

The content of the acetoacetyl group in the water-soluble acetoacetylated polyvinyl alcohol-based resin is 0.05 mol% or more and can be selected within the range of the water solubility of the resin, but is usually 0.
It is preferable to select from the range of 1 to 40 mol%, especially 0.2 to 20 mol%.

If the acetoacetyl group content is too low, the water resistance effect is insufficient and the object of the present invention cannot be achieved. Further, even if it is increased more than necessary, the water resistance effect is not improved and the water solubility is out of the range. More often.

The saponification degree of the acetoacetylated polyvinyl alcohol resin is preferably 70 to 100 mol%, and the preferable degree of polymerization is 300 to 2,000.

The above-mentioned water-soluble acetoacetylated polyvinyl alcohol-based resin has low toxicity to the living body. For example, the acute toxicity of acetoacetylated polyvinyl alcohol having an acetoacetyl group content of 5 mol% and a saponification degree of 99 mol% is LD ₅₀ 8 g / Values above Kg (rats) have been obtained. (Institute of Life Science, test report, dated May 10, 1984) In the present invention, the compounding ratio of the water-soluble acetoacetylated polyvinyl alcohol resin to the water-soluble seaweed polysaccharide depends on the purpose of water resistance. The content ratio of acetoacetyl groups based on the total dry solid content of the water-soluble seaweed polysaccharide and the water-soluble acetoacetylated polyvinyl alcohol resin is 3 × 10 ^-2. ~
It is selected to be 5 × 10 ^-1 mmol / g.

If the content of the acetoacetyl group in the composition is too low,
It is difficult to obtain a sufficient water resistance effect, and even if it is made higher than necessary, the effect of improving the water resistance efficiency of the fiber and the interfiber bond strength of the fiber sheet cannot be obtained, and the characteristics of the water-soluble seaweed polysaccharide are lost. I will end up.

The dope for spinning varies depending on the degree of polymerization of the alginic acid or acetoacetylated polyvinyl alcohol resin used, but usually the solid content of the above formulation is in the range of 0.1 to 20% by weight, and the viscosity of the dope is 500 to Adjust within the range of 10,000cps / 20 ℃. When the solid content concentration of the dope is too low, the coagulation force of the spinning solution is insufficient, and spinning becomes difficult, while when the solid content concentration of the dope is too high, the viscosity becomes high, and it becomes difficult to remove excess air and defoam. The spinnability is impaired.

The pH of the dope is 6-11 to maintain the stability of the dope.
It is preferable to adjust to the range.

The conditioned dope is then subjected to excess and defoaming. As the overuse material, any material such as cotton flannel and sintered metal can be used. As the defoaming device, a known device such as an instantaneous defoaming device that causes the dope to flow out in a thin film under high vacuum can be used.

The dope thus defoamed is supplied to a wet spinning machine and spun into a coagulating liquid through a spinning nozzle.

As the coagulating liquid, an aqueous solution containing 0.01 to 5 g atom / ion of polyvalent metal excluding mercury and magnesium can be used, but above all, the range of 0.1 to 1.0 atom / is less toxic to enzymes and living bodies. It is suitable.

The draft ratio of the spinning solution in the coagulating solution is selected from the range of 5 to 50.

After removing the coagulation liquid excessively attached to the surface of the coagulated fibrous material, dehydration drying is performed. No special heating is required for this dehydration drying, but hot air or reduced pressure may be used to increase the drying speed.

Further, the effect of making the fibers themselves water resistant can be more easily obtained by irradiating with actinic rays prior to or during the drying process. It is effective to carry out this actinic ray irradiation when the water content of the irradiated body is 20% by weight or more, preferably 30% by weight or more.

The types of actinic rays are electron rays, α rays, β rays, γ
In addition to artificial rays such as X-rays and X-rays, sunlight can be used, but UV rays are usually used because of the simplicity of equipment and safety of work. Any light source may be used, such as a low pressure mercury lamp,
A high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a xenon lamp, etc. can be used.

The irradiation dose required for waterproofing the composition of the present invention is, for example, 10
In the case of a sheet having a thickness of 0 μm, it is suitable to set the light amount to 3 × 10 ^{4 to} 3 × 10 ⁵ μW / sec · cm ² for about 0.5 to 10 seconds.

In the method of the present invention, the fiber containing the water-soluble seaweed polysaccharide as a main component obtained as described above is further prepared by Kobayashi et al. In Journal of Applied Polymer Science, 31 , 1735.
1747 (1986), JP-A-61-174499 and the like can be made into a sheet based on the method.

That is, the fiber obtained by the above-mentioned method is not necessarily required to have a common natural pulp stock preparation method, particularly a mechanical treatment such as a beating treatment, and is made stable fiber like rayon or natural fiber papermaking. , Its shape is fiber length /
By setting the fiber diameter, that is, the aspect ratio to 150 or less, dispersion is possible in water without optical entanglement, and a fiber sheet having self-adhesion and sufficient dry and wet strength can be obtained.

Incidentally, in forming the sheet, depending on the intended use, it is also possible to mix a plurality of types of water-soluble seaweed-based polysaccharide fibers to form a seal, and further, natural pulp, rayon, vinylon,
General fibers such as polyester and nylon, inorganic fibers such as carbon fibers, titanium fibers and boron fibers or metal fibers may be mixed to form a sheet.

In the method of the present invention, after the fibers obtained by the above method are formed into a sheet, the actinic ray treatment described in detail above is performed in a state where the water content of the sheet is 20% by weight, preferably 30% by weight or more. Thereby, the effect of improving the interfiber bonding strength, that is, the effect of improving the wet strength of the sheet can be more easily obtained.

[Effect] According to the production method of the present invention, a composition comprising a water-soluble seaweed-based polysaccharide and an acetoacetylated polyvinyl alcohol-based resin is water-soluble and an enzyme utilizing the fact that it has low toxicity to enzymes and microorganisms, A water-soluble or water-dispersible functional substance such as a microorganism or a biochemical diagnostic agent can be included at the time of forming the fiber sheet of the composition, and there is almost no effect on the included functional substance. Can be made water resistant.

The production method of the present invention is extremely useful as a production method of various functional fiber sheets as described above as well as a production method of a fiber sheet having low toxicity to living bodies and excellent wet strength.

[Examples] Next, the production method of the present invention will be described more specifically with reference to Examples. Hereinafter, “part” or “%” is shown on a weight basis unless otherwise specified.

The “dry solid content of the composition” of the present invention in the following examples is obtained by the following method.

Method for measuring the dry solid content of the composition: 1 to 3 g of a sample was precisely weighed (Ag), dried in a hot air dryer at 110 ° C. for 3 hours, then allowed to cool in silica gel, and the weight (Bg) after drying was measured. Measure and calculate from dry solid content (%) = (B / A) x 100.

Reference Example 1 Acetoacetylation degree of 5 mol% and saponification degree of sodium alginate (type H manufactured by Kimitsu Chemical Co., Ltd.)
A composition containing 99 mol% of acetoacetylated polyvinyl alcohol having a degree of polymerization of 1,100 (dry solid content ratio of 100: 10, acetoacetyl group content in the dry solid content of 0.1 mmol / g) and 4% of dry solid content After passing the aqueous solution through a heating machine and paper NO.60 (manufactured by Toyo Kagaku Sangyo Co., Ltd.), use a wet spinning machine at a spinning speed of 13.7 ml / min to obtain 5% from a 1,000-hole spinneret with a 0.1 mm bore. A filament having a water content of 30% and a fiber diameter of 15 μm (air-dried) was obtained by spinning in a coagulating liquid composed of an aqueous solution of calcium chloride and winding at a speed of 7.1 m / min and drying at 60 ° C.

A part of the obtained filament was vacuum dried for further 15 hours to obtain “dry fiber”. Further, another part of the filament was irradiated with ultraviolet rays at 3 × 10 ⁴ μW / sec · cm ^{2 for} 2 seconds and then vacuum dried for 15 hours to obtain “UV-irradiated fiber”. These "dry or UV-irradiated fibers" were conditioned at 20 ° C and 65% RH for 3 days, and then the dry strength and wet strength were determined by the following methods.

Measuring method of dry strength and wet strength of fiber: Wet strength of the fiber after conditioning is kept as it is, and the wet strength is measured by immersing the sample in water at 20 ℃ for 30 seconds, then using a tensilon, the distance between chucks is 100 mm and the pulling speed is 40 mm. A tensile test was performed at / min to determine the dry strength and the wet strength, respectively. The number of repeated measurements in the tensile test was 6.

Reference Example 2 The dry strength and wet strength of the “dry or UV-irradiated” fiber obtained in the same manner as in Reference Example 1 except that acetoacetylated polyvinyl alcohol was not blended were measured.

 The above results are summarized in Table 1.

Example 1 The "dry fiber" obtained in Reference Example 1 was cut into a fiber length of 3 mm with a guillotine cutter, and further passed through a flat screen having a slit width of 6 mil to remove the bundled fibers.

The short fibers were dispersed in water containing 0.05% polyethylene oxide to prepare a 0.2% dispersion, and the paper was made using a TAPPI standard sheet machine so that the basis weight was about 50 g / m ² .

Then, after dehydration by press, it was dried under press at 105 ° C. for 5 minutes to obtain a “dry sheet” having a basis weight of 50 g / m ² .

Separately, press-dehydrated into a sheet with a water content of 50%.
× 10 ⁴ μW / sec ・ cm ² After irradiating ultraviolet rays for 2 seconds,
It was dried under a press at 105 ° C. for 5 minutes to obtain a “UV irradiation sheet” having a basis weight of 50 g / m ² .

These sheets were wetted at 20 ° C. and 65% RH for 3 hours, and then the dry strength and wet strength were measured by the following methods.

 The results are summarized in Table 2.

Measuring method of dry strength and wet strength of sheet: Test piece for measurement (width 15mm, from sheet after wetting)
Length 200 mm), dry strength as it is, wet strength after immersing the test piece in water at 20 ℃ for 30 seconds,
Tensile strength was measured using a Tensilon at a chuck distance of 150 mm and a tensile speed of 100 mm / min. The number of repeated measurements was 6.

Example 2 In Example 1, instead of “the“ dried fiber ”obtained in Reference Example 2”, ““ the UV-irradiated fiber ”obtained in Reference Example 1”
The "dry sheet" obtained in the same manner as in Example 1 except that was used was measured for dry strength and wet strength.

 The results are shown in Table 3.

Control Example 2 Obtained in the same manner as in Example 1 except that the “dry fiber” obtained in Reference Example 1 was replaced with the “dry fiber” obtained in Reference Example 2. "Dry sheet"
Also, the dry strength and wet strength of the “UV irradiation sheet” were measured.

 The results are summarized in Table 3.

Examples 3 to 6 Compositions in which the compounding ratio of acetoacetylated polyvinyl alcohol to sodium alginate was changed to 100: 2, 100: 20, 100: 40 in dry solid ratio in Reference Example 1, or the degree of acetoacetylation to sodium alginate was 10 mol%.
Using a composition in which the blending ratio of acetoacetylated polyvinyl alcohol having a saponification degree of 99 mol% and a polymerization degree of 1,100 was 100: 40, "dry fiber" and " UV irradiation fiber "was obtained.

The results of measuring the dry strength and the wet strength of the “dry sheet” and the “UV irradiation sheet” obtained from these fibers by the same method as in Example 1 are summarized in Table 4.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Kageyama 2-6-18 Manoren, Ikeda-shi, Osaka (72) Inventor Shuji Tsutsumi 759-11 Nomura-cho, Kusatsu-shi, Shiga Examiner Shigemi Sawamura

Claims (7)

(57) [Claims] 1. A composition comprising a water-soluble seaweed-type polysaccharide and a water-soluble acetoacetylated polyvinyl alcohol-type resin, which is molded into a fibrous sheet to contain the water-soluble seaweed-type polysaccharide as a main component. A method for producing a fiber sheet having excellent water resistance. 2. A composition comprising a water-soluble seaweed-based polysaccharide and a water-soluble acetoacetylated polyvinyl alcohol-based resin, which is a dry solid of the water-soluble seaweed-based polysaccharide and the water-soluble acetoacetylated polyvinyl alcohol-based resin. Content of acetoacetyl group to the total amount of 3 × 10 ^{-2 to} 5 × 10 ^-1 mmol
Claim 1 which is compounded so that it becomes / g.
The manufacturing method described in the item. 3. The water-soluble seaweed polysaccharide is alginic acid and / or an alkali metal alginic acid salt.
Item 2. The method according to item 2 or item 2. 4. A water-soluble seaweed characterized in that a composition comprising a water-soluble seaweed-type polysaccharide and a water-soluble acetoacetylated polyvinyl alcohol-type resin is molded into a fiber sheet and then irradiated with actinic rays. A method for producing a fiber sheet having an excellent water resistance, which is mainly composed of a polysaccharide. 5. The method according to claim 4, wherein the actinic radiation is applied in a state where the water content of the molded fibrous sheet material is 20% by weight or more on a dry basis. 6. A composition comprising a water-soluble seaweed-based polysaccharide and a water-soluble acetoacetylated polyvinyl alcohol-based resin, which is a dry solid of the water-soluble seaweed-based polysaccharide and the water-soluble acetoacetylated polyvinyl alcohol-based resin. Content of acetoacetyl group to the total amount of 3 × 10 ^{-2 to} 5 × 10 ^-1 mmol
Claim 4 which is compounded so that it becomes / g.
Item 5 or the production method according to Item 5. 7. The water-soluble seaweed-type polysaccharide is alginic acid and / or an alkali metal alginic acid salt.
Item 5. The method according to Item 5 or 6.