阅读说明：本技术 聚乙烯醇类纤维 (Polyvinyl alcohol fiber ) 是由 野中寿 和志武洋祐 关谷真司 远藤了庆 于 2019-10-25 设计创作，主要内容包括：聚乙烯醇类纤维包含聚乙烯醇类聚合物和吸附剂。相对于聚乙烯醇类聚合物100质量份,吸附剂的比例为30～500质量份,聚乙烯醇类纤维中的聚乙烯醇的结晶度为30～60％,所述聚乙烯醇类纤维的纤维直径为5～1000μm,且比表面积为10～2000m～2/g。(The polyvinyl alcohol fiber comprises a polyvinyl alcohol polymer and an adsorbent. The adsorbent is contained in an amount of 30 to 500 parts by mass per 100 parts by mass of a polyvinyl alcohol polymer, the polyvinyl alcohol in the polyvinyl alcohol fiber has a crystallinity of 30 to 60%, and the polyvinyl alcohol fiber has a fiber diameter of 5 to 1000 μm and a specific surface area of 10 to 2000m 2 /g。)

1. A polyvinyl alcohol based fiber comprising a polyvinyl alcohol based polymer and an adsorbent, wherein,

the adsorbent is contained in an amount of 30 to 500 parts by mass per 100 parts by mass of the polyvinyl alcohol polymer,

the crystallinity of polyvinyl alcohol in the polyvinyl alcohol fiber is 30-60%,

the polyvinyl alcohol fiber has a fiber diameter of 5 to 1000 μm and a specific surface area of 10 to 2000m²/g。

2. The polyvinyl alcohol-based fiber according to claim 1, wherein the effective utilization rate of the adsorbent is 50 to 100%.

3. The polyvinyl alcohol-based fiber according to claim 1 or 2, which has a degree of swelling of 150 to 600%.

4. The polyvinyl alcohol-based fiber according to any one of claims 1 to 3, wherein the adsorbent is at least 1 selected from the group consisting of a layered silicate, a porous carbon material, and an aluminosilicate.

5. The polyvinyl alcohol-based fiber according to any one of claims 1 to 4, wherein the average particle diameter of the adsorbent is 0.1 to 100 μm.

6. A fiber structure comprising the polyvinyl alcohol-based fiber according to any one of claims 1 to 5 in at least a part thereof.

7. The fiber structure according to claim 6, which is an adsorbent that adsorbs an adsorbate contained in a treatment object.

Technical Field

The present invention relates to a polyvinyl alcohol fiber containing an adsorbent.

Background

At present, an adsorbent for adsorbing and removing an adsorbate contained in a treatment liquid is used.

For example, as an adsorbent for selectively adsorbing and removing phosphorus, boron, arsenic, and the like contained in river water, sewage treatment water, and plant wastewater, a method of purifying water by impregnating an inorganic ion adsorbent such as activated alumina with aluminum sulfate has been proposed. It has been described that the treatment speed of an adsorbate is improved by supporting the inorganic ion adsorbent on an organic polymer resin such as an ethylene vinyl alcohol copolymer and using a porous molded body containing the organic polymer resin and the inorganic ion adsorbent (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2006-297382

Disclosure of Invention

Problems to be solved by the invention

However, the molded article described in patent document 1 has a problem that sufficient adsorbability cannot be exhibited because the adsorbent has a portion covered with a hydrophobic polymer. Further, if the adsorption capacity cannot be sufficiently exhibited, the adsorbent must be used in excess to exhibit the required adsorption capacity, and therefore, there is a problem that a large processing cost is required and the facility becomes large. Further, since the molded article described in patent document 1 is substantially spherical, it is difficult to process the molded article into a suitable form depending on the application and the method of use, and the use of a processing method limited to the use of a dedicated facility such as a storage tank or a column is limited, and there is a burden in terms of cost and space for introducing the facility. Further, since the molded article is spherical, recovery of the adsorbent after treatment is complicated, and a large amount of labor is required, which causes a problem in handling.

Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a polyvinyl alcohol fiber having excellent adsorbability and handling properties.

Means for solving the problems

In order to achieve the above object, the polyvinyl alcohol fiber of the present invention comprises a polyvinyl alcohol polymer and an adsorbent, wherein the adsorbent is contained in an amount of 30 to 500 parts by mass per 100 parts by mass of the polyvinyl alcohol polymer, the polyvinyl alcohol in the polyvinyl alcohol fiber has a crystallinity of 30 to 60%, the polyvinyl alcohol fiber has a fiber diameter of 5 to 1000 μm and a specific surface area of 10 to 2000m²/g。

Effects of the invention

According to the present invention, a polyvinyl alcohol fiber having excellent adsorbability and handling properties can be provided.

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) photograph of the polyvinyl alcohol-based fiber produced in example 1.

Fig. 2 is a Scanning Electron Microscope (SEM) photograph of the polyvinyl alcohol-based fiber produced in example 5.

Detailed Description

The present invention will be described in detail below. The polyvinyl alcohol-based fiber (hereinafter, referred to as "PVA-based fiber") of the present invention includes a polyvinyl alcohol-based polymer (hereinafter, referred to as "PVA-based polymer") and an adsorbent.

< PVA based Polymer >

The PVA-based polymer constituting the PVA-based fiber of the present invention is not particularly limited as long as it contains a vinyl alcohol unit as a main component, and may have other structural units. Examples of such a structural unit include olefins such as ethylene, propylene and butene, acrylic acid and salts thereof and acrylic acid esters such as methyl acrylate, methacrylic acid and salts thereof, methacrylic acid esters such as methyl methacrylate, acrylamide derivatives such as acrylamide and N-methacrylamide, methacrylamide derivatives such as methacrylamide and N-methylol methacrylamide, N-vinyl amides such as N-vinylpyrrolidone, N-vinyl formamide and N-vinyl acetamide, allyl ethers having polyalkylene oxide in the side chain, vinyl ethers such as methyl vinyl ether, nitriles such as acrylonitrile, vinyl halides such as vinyl chloride, and unsaturated dicarboxylic acids such as maleic acid and salts or anhydrides thereof and esters thereof. The method of introducing such a modifying unit may be a method based on copolymerization or a method based on post-reaction.

The saponification degree of the PVA-based polymer of the present invention is not particularly limited, but is preferably 98 mol% or more, and more preferably 99 mol% or more, from the viewpoint of crystallinity and orientation of the obtained fiber. In addition, the saponification degree of 99.7 mol% or more, the hot water resistance is excellent, so the preferred.

The polymerization degree of the PVA based polymer of the present invention is not particularly limited, and the average polymerization degree determined from the viscosity of an aqueous solution at 30 ℃ is preferably 1200 to 20000 in consideration of the mechanical properties, dimensional stability and the like of the obtained fiber. When a polymer having a high polymerization degree is used, it is preferable that the polymer is excellent in strength, moist heat resistance and the like, but from the viewpoint of cost for producing the polymer, cost for fiberizing the polymer and the like, the average polymerization degree is particularly preferably 1500 to 5000.

The "average degree of polymerization" referred to herein can be determined from the viscosity of an aqueous solution at 30 ℃ in accordance with the specification of JIS K6726: 1994.

The content of the PVA based polymer is preferably in the range of 20 to 77% by mass based on the total amount of the PVA based fibers. This is because when the content of the PVA-based polymer is less than the above range, it may be difficult to form PVA-based fibers, and when the content of the PVA-based polymer is more than the above range, the adsorption performance may not be sufficiently exhibited when the PVA-based polymer is used as an adsorbent.

The lower limit of the content of the PVA-based polymer relative to the total amount of the PVA-based fibers is more preferably 25 mass% or more. The content of the PVA-based polymer is more preferably 50% by mass or less with respect to the upper limit of the PVA-based fiber as a whole.

< adsorbent >

The adsorbent of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and any adsorbent can be used, which adsorbs harmful pollutants (heavy metals) contained in a treatment object such as soil, wastewater from rivers and factories, and water for civil engineering works, odorous substances (for example, odorous components discharged from research facilities, factories, and treatment facilities, odorous components emitted from body fluids, odorous components generated from reagents, and the like), organic halogen-containing compounds, other unnecessary organic substances, and the like (for example, miscellaneous flavor components, turbid components, coloring matters in foods and beverages, and hardly decomposable organic substances discharged from food processing and fiber processing steps).

For example, adsorbents such as carbon, zeolite, silicate, and metal compound can be exemplified. Examples of the carbon include porous carbon materials such as activated carbon from which odor substances, organic halogen-containing compounds, residual chlorine, other toxic substances, harmful substances, and the like are removed. Examples of the zeolite include artificial zeolite and natural zeolite from which metal ions such as ammonia, organic amine, cesium, boron, potassium, magnesium, and calcium have been removed. Examples of the silicate include layered silicates such as bentonite and aluminosilicate. Examples of the metal compounds include metal oxides and metal hydroxides from which heavy metals such as lead, phosphorus, arsenic, and cadmium are removed, such as iron, magnesium, calcium, and aluminum.

In the present invention, these adsorbents may be used alone or in combination of 2 or more.

In the PVA based fiber of the present invention, the content of the adsorbent is 30 to 500 parts by mass per 100 parts by mass of the PVA based polymer. This is because when the content of the adsorbent is less than the above range, the coverage of the adsorbent by the PVA-based polymer increases, and therefore, the permeability of the treatment liquid decreases, and as a result, the adsorbability to the adsorbate contained in the treatment liquid may not be sufficiently exhibited. Further, when the content of the adsorbent exceeds the above range, the PVA-based fibers may be difficult to form a fibrous shape (i.e., fiberization), and a large amount of the adsorbent may fall off from the PVA-based fibers and be mixed into the treatment liquid, thereby deteriorating the handling properties.

That is, by setting the content of the adsorbent to 30 to 500 parts by mass with respect to 100 parts by mass of the PVA-based polymer, fine pores for adsorbing an adsorbate can be formed, and a PVA-based fiber having excellent adsorbability can be obtained without causing a problem that the adsorbent falls off from the fiber and is mixed into the treatment liquid (see fig. 1 and 2 of examples described later).

The lower limit of the content of the adsorbent is preferably 100 parts by mass or more with respect to 100 parts by mass of the PVA-based polymer. The upper limit of the content of the adsorbent is preferably 300 parts by mass or less with respect to 100 parts by mass of the PVA based polymer.

The average particle size of the adsorbent is not particularly limited, but is preferably 0.1 to 100 μm. If the amount is less than the above range, it becomes difficult to form fine pores in the fibers, and thus the permeability of the treatment liquid into the fibers may decrease, resulting in a decrease in the adsorbability of the adsorbent. When the amount exceeds the above range, the PVA-based fibers are difficult to be formed into a fiber shape, and a large amount of the adsorbent may fall off from the PVA-based fibers and be mixed into the treatment liquid, thereby deteriorating the handling property.

The lower limit of the average particle size of the adsorbent is more preferably 0.5 μm or more. The upper limit of the average particle diameter of the adsorbent is more preferably 30 μm or less, and still more preferably 10 μm or less.

The "average particle diameter" referred to herein means a 50% particle diameter (D50), and can be measured by a particle size distribution measuring apparatus (particle size distribution measuring apparatus UPA-EX150, manufactured by japan ltd., nanosrac (registered trademark)) using a laser doppler method or the like.

< PVA based fiber >

The PVA-based fiber of the present invention has pores inside the fiber, and therefore, an adsorption object rapidly penetrates into the fiber, and a contact area with the object is large, and therefore, a high adsorption effect can be exhibited. The degree of crystallinity of PVA in the fibers of the PVA based fibers of the present invention is 30 to 60%. Since the PVA-based fibers having a crystallinity in this range have appropriate hydrophilicity, the treatment liquid has low diffusion resistance in the PVA region, and the performance of the adsorbent is not impaired even in a state covered with PVA. Further, since it has a suitable strength, it can be processed into various forms such as a cotton form, a nonwoven fabric, a woven fabric, and paper, depending on the application. On the other hand, when the crystallinity of PVA in the fibers of the PVA-based fibers is lower than the above range, elution of PVA or falling off of the adsorbent occurs during treatment, and turbidity of the treatment liquid is significantly increased, and thus the operability is poor. When the crystallinity of PVA in the fibers of the PVA-based fibers exceeds the above range, moderate hydrophilicity is impaired, permeability of the treatment liquid is poor, and adsorption performance is impaired.

That is, by setting the crystallinity of PVA in the fibers of the PVA-based fibers to 30 to 60%, the morphological workability and the handleability can be improved without impairing the adsorption performance.

The lower limit of the crystallinity of the PVA-based fibers is preferably 40% or more. The upper limit of the crystallinity of the PVA-based fibers is preferably 55% or less, and more preferably 50% or less. The crystallinity can be determined by the method described later.

The PVA based fiber of the present invention has a fiber diameter of 5 to 1000. mu.m. This is because when the fiber diameter of the PVA-based fiber is less than the above range, sufficient strength may not be obtained in processing and handling, and when it exceeds the above range, flexibility is poor, and processing may be difficult.

The lower limit of the fiber diameter of the PVA-based fibers is preferably 10 μm or more, and more preferably 20 μm or more. The upper limit of the fiber diameter of the PVA based fiber is preferably 500 μm or less, and more preferably 100 μm or less.

The specific surface area of the PVA fiber is 10-2000 m²(ii) in terms of/g. If the amount is less than the above range, the fiber inner pores are too small, and thus the permeability of the treatment liquid is low, and the adsorption rate may be significantly reduced, and if the amount exceeds the above range, the fiber inner pores are too large, and thus the processability of the fiber may be reduced, and the adsorbent may be detached.

The lower limit of the specific surface area of the PVA based fibers is preferably 20m²A value of 40m or more, more preferably 40m²More than g. The upper limit of the specific surface area of the PVA based fibers is preferably 1000m²A ratio of the total amount of the components to the total amount of the components is 500m or less²The ratio of the carbon atoms to the carbon atoms is less than g. The specific surface area can be determined by the method described later.

That is, the PVA based fibers are set to have a fiber diameter of 5 to 1000 μm and a specific surface area of 10 to 2000m²(iv)/g, a PVA based fiber excellent in handling properties and adsorptivity can be obtained.

The PVA-based fiber preferably has a degree of swelling with fiber of 150 to 600%. This is because when the degree of swelling of the fibers is less than the above range, the permeability of the treatment liquid is lowered, and therefore the adsorbability may be lowered. When the degree of swelling of the fibers exceeds the above range, the fibers themselves absorb a large amount of the treatment liquid, and therefore, recovery or replacement after the adsorption treatment becomes difficult due to dimensional change accompanying the swelling of the fibers, and elution of the PVA-based resin and falling of the adsorbent from the PVA-based fibers become easy, and therefore, the workability is deteriorated. Further, the gap through which the treatment liquid passes becomes small, and the liquid permeability is lowered.

That is, by setting the degree of swelling of the PVA-based fibers to 150 to 600%, PVA-based fibers having excellent adsorbability can be reliably obtained without causing deterioration in handleability and liquid permeability.

The lower limit of the degree of swelling of the PVA-based fibers is more preferably 200% or more. The upper limit of the degree of swelling of the PVA-based fibers is more preferably 500% or less, and still more preferably 400% or less.

Here, the "degree of swelling of the fiber" refers to the degree of swelling of the fiber calculated by the formula (1) described later.

The effective utilization rate of the adsorbent in the PVA fiber is preferably 50-100%. This is because when the effective utilization rate is lower than the above range, the adsorbability is lowered, and therefore, a large amount of fibers may be required for the treatment.

That is, by setting the effective utilization rate of the PVA-based fibers to 50 to 100%, the PVA-based fibers having excellent adsorbability can be reliably obtained without causing a reduction in operability.

The lower limit of the effective utilization rate of the PVA-based fibers is more preferably 60% or more, and still more preferably 70% or more.

Here, the "effective utilization rate" refers to a ratio at which the adsorbent is sufficiently utilized, which is calculated by using the formula (3) described later.

Thus, the PVA-based fibers of the present invention have excellent affinity with the adsorbent, and the PVA-based polymer having high hydrophilicity is used as the resin component, and the fine particulate adsorbent is uniformly contained at a high content rate, so that the PVA-based fibers having excellent handling properties and adsorptivity can be obtained.

The PVA-based fiber of the present invention can be produced by any spinning method of solution spinning, specifically wet spinning, dry-wet spinning, and dry spinning, from a spinning solution containing the PVA-based polymer and the adsorbent. As the solvent used in the dope, in the production of the PVA-based fibers, conventionally used solvents, for example, 1 kind of polyhydric alcohols such as dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, methanol, water, glycerin, ethylene glycol, and triethylene glycol, diethylenetriamine, and thiocyanate (rhodan salt), or 2 or more kinds of solvents in combination can be used.

Among them, DMSO and water are particularly preferable from the viewpoint of the supply property and the influence on the environmental load. The polymer concentration in the spinning dope varies depending on the composition, polymerization degree and solvent of the PVA based polymer, and is usually in the range of 6 to 60 mass%.

The spinning dope may contain additives such as an antioxidant, an antifreeze, a pH adjuster, a masking agent, a colorant, and an oil agent, in addition to the PVA-based polymer and the adsorbent, as long as the effects of the present invention are not impaired.

The PVA-based fibers of the present invention may be used in all fiber forms such as short fibers, filament yarns, and spun yarns. The cross-sectional shape of the fiber is not particularly limited, and may be a circular, hollow, star-shaped or other irregular cross-section.

In addition, the fibers of the present invention may also be mixed/combined with other fibers. In this case, the fibers that can be mixed and used in combination are not particularly limited, and examples thereof include PVA-based fibers, polyester-based fibers, polyamide-based fibers, and cellulose-based fibers that do not contain an adsorbent. Further, the fiber structure may be used in the form of a fiber structure such as a crimped cotton, a woven fabric, a nonwoven fabric, a knitted fabric, and paper.

The fiber structure of the present invention can be suitably used for all applications such as food/beverage applications, clothing applications, medical applications, agricultural applications, and water treatment applications, and can be used in liquid or gas including steam. More preferably, the adsorbent is used in an aqueous solution, and may be used, for example, as an adsorbent for adsorbing an adsorbate contained in a treatment liquid (for example, an adsorption filter for removing heavy metals such as cadmium, lead, arsenic, and fluorine contained in soil and river water, an adsorption filter for adsorbing a foreign flavor component and a turbid component contained in food and drink, an adsorption filter for adsorbing a coloring matter, and an adsorption filter for adsorbing an odor component), and various adsorption filters made of a fibrous structure such as filament, chopped fiber, crimped cotton, woven fabric, knitted fabric, and paper.

In addition, the PVA-based fibers of the present invention can be used in the following cases: the chopped short fibers are put into a treatment liquid tank for treatment; forming the crimped cotton into a fiber rod shape, and introducing a treatment liquid into the fiber rod shape for treatment; forming into filament shape and making into spool box, introducing treatment liquid therein and treating; and, for example, a case where a treatment liquid is passed through a tubular or sheet-shaped woven or nonwoven fabric and treated.

Examples

The present invention will be described below based on examples. The present invention is not limited to these examples, and variations and modifications may be made to these examples based on the gist of the present invention, and these are also included in the scope of the present invention.

(example 1)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 150 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 580 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn 3 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn in a hot air oven at 230 ℃ so that the total draw ratio was 5 times, and a fiber having a fiber diameter of 30 μm was obtained.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

The produced fibers were observed with a Scanning Electron Microscope (SEM). Fig. 1 shows a Scanning Electron Microscope (SEM) photograph of the produced fiber. As shown in fig. 1, it is understood that a large number of micropores are formed on the surface of the produced fiber.

< evaluation of spinning Property >

The spinnability was evaluated according to the following evaluation criteria. The results are shown in table 1.

In dry-wet spinning, continuous fibers can be collected: o-

In dry-wet spinning, continuous fibers cannot be collected: is prepared from

< determination of crystallinity >

[ degree of crystallinity (Xc)% ]

Measurement of the degree of crystallization of PVA in the fiber the enthalpy of fusion of the fiber was measured using a Pyris-1 type differential scanning calorimeter manufactured by Perkin Elmer. The measurement conditions were carried out at a temperature rise rate of 80 ℃ per minute, and the gravimetric crystallinity was calculated by the following equation. Note that indium and lead were used as standard substances, and the melting point and the heat of fusion were corrected. The results are shown in table 1.

Xc(％)＝ΔHp/ΔHcal×100

Δ Hp: heat of fusion (J/g) of PVA in fiber

Δ Hobs: measured Heat of fusion (J/g) of fiber

Δ Hp ═ Δ Hobs/(mass of PVA/mass of PVA-based fiber)

Δ Hcal: heat of fusion for complete crystallization (174.5J/g)

< evaluation of specific surface area of fiber (BET method) >)

The specific surface area of the fiber was evaluated using a flow method BET1 point method specific surface area measuring device (Monosorb manufactured by Quantachrome corporation). Pretreatment attached to the apparatus is in N₂The mixture was degassed at room temperature for 30 minutes under an air atmosphere. In the measurement, a mixed gas (N) was flowed into a U-shaped cell containing a sample₂30% He 70%), the sample chamber was cooled to liquid nitrogen temperature (77K) to allow only N₂Gas adsorbs to the surface of the sample. The results are shown in table 1.

< determination of the degree of swelling >

The prepared fiber (about 1g) was dried in a vacuum dryer at 80 ℃ for 24 hours, and the absolute dry fiber weight was measured. Subsequently, the fibers were immersed in ion-exchanged water at 20 ℃ for 60 minutes. Next, the fiber was filtered and taken out, water droplets adhered to the surface were gently removed with filter paper, and then the weight of the fiber after impregnation was measured. Then, the swelling degree of the produced fiber was calculated by the following formula (1). The results are shown in table 1.

[ mathematical formula 1]

Degree of swelling (%) of fiber (weight of fiber after impregnation ÷ absolute dry fiber weight) × 100(1)

< evaluation of adsorption >

As an index of the adsorption property, the removal performance (adsorption rate) of methylene blue as a water-soluble compound was evaluated. More specifically, the fiber was added in an amount of 1% by mass based on 500mL of an aqueous solution containing 100ppm of methylene blue, and the mixture was stirred at 30 ℃ for 60 minutes. Then, the treated liquid was collected, and the maximum absorption wavelength at 664nm was measured using a Spectrophotometer (product name: U-2001Spectrophotometer, manufactured by HITACHI corporation) to calculate the concentration of methylene blue after the treatment. Then, the adsorption rate of the produced fiber was calculated by the following formula (2). The results are shown in table 1.

[ mathematical formula 2]

Adsorption rate (%) of methylene blue (methylene blue concentration of untreated solution-methylene blue concentration after treatment) ÷ (methylene blue concentration of untreated solution) × 100 (2)

< determination of turbidity >

The supernatant of the treatment solution immediately after the evaluation of the adsorption property was collected, and the turbidity (mg/L) was measured using a turbidity meter (2100P portable turbidity meter manufactured by HACH Co.). The results are shown in table 1. It is considered that the higher the turbidity value is, the more difficult the recovery of the treatment liquid becomes, and therefore, the operability is poor.

< determination of effective utilization >

After the adsorption rate of the fibers was measured by the above-mentioned method, the adsorption rate of only the adsorbent itself was measured by the same method using the same amount of the adsorbent as the amount of the adsorbent contained in the fibers. Then, the effective utilization rate of the adsorbent in the fiber was calculated by the following formula (3).

[ mathematical formula 3]

Effective utilization rate (%) - (adsorption rate of fiber) ÷ (adsorption rate of adsorbent) × 100 (3)

(example 2)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 300 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 930 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a spinning dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn 2.5 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn in a hot air oven at 230 ℃ so that the total draw ratio was 4 times, to obtain a fiber having a fiber diameter of 50 μm.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

(example 3)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 150 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 580 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 2.0mm and a hole number of 1 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn 3 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn with a hot air furnace at 230 ℃ so that the total draw ratio was 5 times, and a fiber having a fiber diameter of 400 μm was obtained.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

(example 4)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 150 parts by mass of zeolite (trade name: SP #600, manufactured by Nidong powdered Industrial Co., Ltd., average particle diameter: 2 μm) were dispersed in 580 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a spinning dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃.

Subsequently, the obtained solidified yarn was wet-drawn 3 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn with a hot air furnace at 230 ℃ so that the total draw ratio was 5 times, and a fiber having a fiber diameter of 80 μm was obtained.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

< evaluation of adsorption >

As an index of the adsorption property, the removal performance (adsorption rate) of calcium ions as cations was evaluated. More specifically, the fibers were added in an amount of 2% by mass per 500mL of the 1ppm calcium ion standard solution, and the mixture was stirred at 30 ℃ for 60 minutes. Then, the treated liquid was collected, and the calcium ion concentration after the treatment was measured using an ICP emission spectrometer (OPTIMA 4300DV, manufactured by PerkinElmer). Then, the adsorption rate of the produced fiber was calculated by the following formula (4). The results are shown in table 1.

[ mathematical formula 4]

Calcium ion adsorption (%) (calcium ion concentration of untreated solution-calcium ion concentration after treatment) ÷ (calcium ion concentration of untreated solution) × 100 (4)

Further, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of fiber, the measurement of swelling degree, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1 described above. The results are shown in table 1.

(example 5)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 150 parts by mass of activated carbon (trade name: Kuraray YP-50F, average particle diameter: 6 μm, manufactured by Korea corporation) were dispersed in 580 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a spinning dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃.

Subsequently, the obtained solidified yarn was wet-drawn 3 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn with a hot air furnace at 230 ℃ so that the total draw ratio was 5 times, and a fiber having a fiber diameter of 80 μm was obtained.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

The produced fibers were observed with a Scanning Electron Microscope (SEM). Fig. 2 shows a Scanning Electron Microscope (SEM) photograph of the produced fiber. As shown in fig. 2, a large number of micropores were formed on the surface of the produced fiber.

< evaluation of adsorption >

As an index of the adsorption property, the removal performance (adsorption rate) of methylene blue as a water-soluble compound was evaluated. More specifically, the fiber was added in an amount of 0.25 mass% per 500mL of an aqueous solution containing 600ppm of methylene blue, and the mixture was stirred at 30 ℃ for 60 minutes. Then, the treated liquid was collected, and the maximum absorption wavelength at 664nm was measured with a Spectrophotometer (product name: U-2001Spectrophotometer, manufactured by HITACHI corporation), and the concentration of methylene blue after the treatment was calculated. Then, the adsorption rate of the produced fiber was calculated by the above formula (2). The results are shown in table 1.

Further, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of fiber, the measurement of swelling degree, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1 described above. The results are shown in table 1.

(example 6)

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 50 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 350 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a spinning dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn 3 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn in a hot air oven at 230 ℃ so that the total draw ratio was 7 times, and a fiber having a fiber diameter of 30 μm was obtained.

The obtained fibers were crimped and cut, and after carding to form a sheet (web), needle punching was performed. A soft nonwoven fabric having good processability was obtained.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

Comparative example 1

A PVA-based fiber was produced in the same manner as in example 1 above, except that the amount of bentonite added was set to 20 parts by mass and the total draw ratio was set to 10 times in the production of the PVA-based fiber.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

Comparative example 2

Dry-wet spinning was performed in the same manner as in example 1, except that the amount of bentonite added was 550 parts by mass in the production of the PVA-based fibers.

In the present comparative example, since the content of bentonite was more than 500 parts by mass, yarn breakage frequently occurred in the spinning step, and it was difficult to form a fiber shape (i.e., fiberization). Therefore, as shown in table 1, the measurement of crystallinity, the evaluation of specific surface area of fiber, the measurement of swelling degree, the evaluation of adsorptivity, the measurement of turbidity and the measurement of effective utilization rate could not be performed.

Comparative example 3

100 parts by mass of PVA (trade name: PVA-117, manufactured by Korea corporation) having an average polymerization degree of 1700 and a saponification degree of 98.0 mol% and 300 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 930 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.15mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn 2.5 times in a methanol bath at 20 ℃ and dried with hot air at 120 ℃ to obtain a fiber having a fiber diameter of 65 μm.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

Comparative example 4

Evaluation of specific surface area, evaluation of adsorption, measurement of turbidity, and measurement of effective utilization rate of 100 parts by mass (powder) of bentonite were carried out in the same manner as in example 1. The results are shown in table 1.

Comparative example 5

< manufacture of PVA based fiber >

100 parts by mass of PVA (trade name: PVA-124, manufactured by Korea corporation) having an average polymerization degree of 2400 and a saponification degree of 98.0 mol% and 150 parts by mass of bentonite (trade name: Kunipia F, average particle diameter: 1 μm, manufactured by Kunimine Industries, Ltd.) were dispersed in 930 parts by mass of DMSO, and the PVA was dissolved by heating at 105 ℃ in a nitrogen atmosphere to prepare a spinning dope.

Next, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 5.0mm and a hole number of 1 in a curing bath composed of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. Subsequently, the obtained solidified yarn was wet-drawn at 1.1 times in a methanol bath at 20 ℃, dried with hot air at 120 ℃, and dry-hot-drawn in a hot air oven at 230 ℃ so that the total draw ratio was 1.2 times, to obtain a fiber having a fiber diameter of 1100 μm.

Although the obtained fibers were crimped, the fibers were frequently broken during the crimping treatment, and the resulting nonwoven fabric was poor in processability.

Then, the evaluation of spinnability, the measurement of crystallinity, the evaluation of specific surface area of the fiber, the measurement of swelling degree, the evaluation of adsorbability, the measurement of turbidity and the measurement of effective utilization rate were carried out in the same manner as in example 1. The results are shown in table 1.

Comparative example 6

A spinning dope was produced in the same manner as in comparative example 5. To produce a fiber having a fiber diameter of 3 μm, the obtained dope was dry-wet spun through a nozzle having a hole diameter of 0.06mm and a hole number of 40 in a curing bath of methanol/DMSO (mass ratio: methanol/DMSO: 70/30) at 5 ℃. However, since the fiber diameter is less than 5 μm, the strength of the cured yarn is very weak, and the workability is also poor, so that winding cannot be performed.

As shown in Table 1, it is understood that the PVA based fibers of examples 1 to 6 have a ratio of the adsorbent of 30 to 500 parts by mass and a crystallinity of 30 to 60% by mass of the polyvinyl alcohol based on 100 parts by mass of the PVA, and have a fiber diameter of 5 to 1000 μm and a specific surface area of 10 to 2000m²Therefore, it is excellent in adsorption and handling properties.

On the other hand, in the PVA-based fiber of comparative example 1, since the proportion of bentonite is less than 30 parts by mass, the coverage of bentonite by PVA is high, and the permeability of the treatment liquid is lowered, so that the adsorption to methylene blue contained in the treatment liquid is low.

In comparative example 3, it is also understood that, since the crystallinity of polyvinyl alcohol is less than 30%, bentonite in the fibers is exfoliated to increase the turbidity and deteriorate the workability.

In addition, in comparative example 4, since only bentonite and not PVA were used, the bentonite was mixed into the treatment liquid to increase turbidity, and the workability was deteriorated.

In comparative example 5, it was found that the fiber diameter was large, and the obtained fiber was difficult to be crimped, and thus it was not possible to form a nonwoven fabric.

Industrial applicability

As described above, the present invention is suitable for a polyvinyl alcohol fiber containing an adsorbent. The fiber structure containing the polyvinyl alcohol-based fiber of the present invention in at least a part thereof can be suitably used for any application such as food/beverage applications, clothing applications, medical applications, agricultural applications, and water treatment applications.