JP2008255550A - Water-swelling fibrillated fiber and sheet-like material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fibrillated fiber in which binder performance such as dispersibility, adhesiveness and drying shrinkage property of an aromatic polyamide fibrid which is existing water-swelling fibrillated fiber are enhanced. <P>SOLUTION: The water-swelling fibrillated fiber is composed of para-aromatic polyamide and satisfies the following items: (a) catching ratio of the fiber using a wire net having 37 μm wire intervals and 42 mesh is ≤3 wt.% and a wire net through content of the fiber using a wire net having 10 μm wire intervals and 140 mesh is ≥30 wt.% in a sieving test, (b) water content of the fiber has 70-99% water content and (c) the fiber has fibrils having ≤100 nm fiber diameter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fibrillated fiber used for applications such as high-performance paper, a sheet-like material containing the same, and a method for producing the same.

  Conventionally, various methods have been proposed for the purpose of enhancing the paper strength of high-performance paper represented by battery / capacitor separator, electrical insulating paper, filter paper, printed wiring board base material, wet friction material paper and the like. For example, (1) increasing the papermaking density, (2) adding a fibrous binder. Although these methods may be effective, an effective method has not yet been found in the field of impregnated paper.

  That is, the method (1) has a limit due to mechanical limitations during manufacturing and does not contribute much to the improvement of strength. Regarding the method (2), a microfibril produced by applying special beating means in which cellulose pulp fibers are suspended in water and repeatedly passed through a homogenizer for high pressure is disclosed in JP-A-58-197400. A method of adding cellulose acetate as a binder has been proposed, and by adding a small amount in the papermaking raw material, the paper strength is certainly enhanced, but since this fiber is made of cellulose, its use in terms of heat resistance etc. There is a problem that the field is restricted.

  On the other hand, in Japanese Patent Application Laid-Open No. 3-152130 and Japanese Patent Publication No. 8-19633, a rigid linear synthetic polymer short fiber such as an aromatic polyamide having excellent heat resistance is used as a raw material, and a beating process is performed by a homogenizer process at high pressure. By adding a fibrous material having many fine fibrils to the papermaking raw material, the strength of the paper sheet is improved by entanglement of the fibrils, and the heat resistance and electrical insulation properties are also reflected, reflecting the physical properties of the polymer itself. It is devised that an excellent paper sheet can be obtained. However, the paper reinforcement mechanism by the fibrils of the rigid linear synthetic polymer short fibers generated by the homogenizer treatment is only entanglement between the fine fibrils, and the reinforcement effect cannot be said to be sufficient.

  On the other hand, the aromatic polyamide fibrids shown in WO2004 / 099476, JP-B-35-11851, JP-B-37-5732, etc. are dried because they retain a large amount of moisture inside the fiber. It is known that it sometimes shrinks greatly and exhibits a binder function for bonding aromatic polyamide fibrids or other components. Therefore, the reinforcing mechanism of the paper to which these are added is not only the adhesion and entanglement of the fibers, but also the holding effect due to drying shrinkage in the entangled state, and a sheet material having higher strength can be obtained. However, an aromatic polyamide fibrid containing a large amount of a component having a large fiber diameter has poor dispersibility of the fibrid when formed into a sheet by a papermaking method or the like, and the binder function has not been fully utilized. Further, fibrillated fibers having improved adhesion and drying shrinkage have been desired.

JP 58-197400 A JP-A-3-152130 Japanese Patent Publication No.8-19633 WO2004 / 099476 Japanese Patent Publication No. 35-11851 Japanese Patent Publication No. 37-5732

  Provided is a fibril fiber having improved binder properties such as dispersibility, adhesion, and drying shrinkage of current aromatic polyamide fibrils.

  It consists of a specific organic polymer, and in the sieving test, the line spacing is 37 μm, the collection rate of 42 mesh wire mesh is 3 wt% or less, the line interval is 10 μm, and the 140 mesh wire mesh passage is 30 wt% or more, A water-swellable fibrillated fiber having a fibril with a fiber diameter of 100 nm or less is 70 to 99%.

  The water-swellable fibrillated fiber is obtained by introducing an organic polymer solution into an aqueous coagulation solution and coagulating it in a state where shearing such as stirring is applied, and / Alternatively, it is obtained by beating the organic polymer polymer-containing molded product as a raw material, and since a large amount of water is retained inside the fiber crystal structure, a known refiner, beater, mill, high-pressure homogenizer, By treating with a crusher or the like, the fiber particle size can be easily reduced, and a large amount of fine fibrils having a fiber diameter of 100 nm or less can be provided. As a result, the surface area is greatly increased, so that not only adhesion and entanglement between fibrids or other components is increased, but also drying shrinkage is increased and the binder function is improved. The sheet-like material containing the water-swellable fibrillated fiber of the present invention is greatly improved in strength and the like.

  The water-swellable fibrillated fiber referred to in the present invention is a general fibrillated fiber (generally a fibrillated fiber is a fiber-forming polymer short fiber refiner, beater, mill, high-pressure homogenizer, grinding device. Unlike a fibrous material having a large number of fibrils formed by mechanically and physically randomly cleaving along its main axis by an apparatus such as a device, a short fiber having a large number of microfibrils and a fiber This means that the degree of fibrillation is further advanced in the case where water molecules or moisture are present in the crystal structure in an amorphous state (sometimes simply referred to as fibrils) without forming a solid crystal structure. . Such a water-swellable fibrillated fiber is obtained by introducing an organic polymer polymer solvent solution into a poor solvent or non-solvent coagulating solution of the organic polymer polymer and coagulating it in a state where shearing such as stirring is applied. It is obtained by further beating a thin leaf-like or scaly piece having fine fibrils formed or randomly fibrillated fine fibers.

  Examples of the “organic polymer” in the present invention include para-type wholly aromatic polyamide, meta-type wholly aromatic polyamide, poly-p-phenylenebenzobisoxazole (PBO) homopolymer, and the like. The type, structure, degree of polymerization, etc. of the polymer are not particularly limited. The polymer is an organic polymer that can be dissolved in a solvent, and the organic polymer is solidified by a coagulation liquid mainly composed of water. There is no particular limitation as long as it is an organic polymer and a solvent.

  In the present invention, “aromatic polyamide” means a linear polymer compound in which 60% or more, preferably 85% or more of amide bonds are directly bonded to an aromatic ring. Examples of such aromatic polyamides include polymetaphenylene isophthalamide and copolymers thereof, polyparaphenylene terephthalamide and copolymers thereof, poly (paraphenylene) -copoly (3,4-diphenyl ether) terephthalamide, and the like. However, it is not limited to this. From the viewpoint of high heat resistance and chemical resistance, polyparaphenylene terephthalamide or poly (paraphenylene) -copoly (3,4-diphenyl ether) terephthalamide which is a copolymer thereof is preferable.

  As a preferred water-swellable fibrillated fiber in the present invention, for example, an aramid polymer solution is prepared by the method described in WO2004 / 099476, JP-B-35-11851, JP-B-37-5732, etc. Molded from a polymer solution exhibiting optical anisotropy by a fibrid produced by mixing with a precipitating agent in a system in which shear force exists, or by the method described in Japanese Patent Publication No. 59-603. Examples of the molded product having molecular orientation may include fibrillation at random by applying mechanical shearing force such as beating.

  The water-swellable fibrillated fiber of the present invention is dried in the production process, and the aromatic polyamide short fiber once subjected to the drying process in the production is highly fibrillated by treatment with a refiner, beater, mill, high-pressure homogenizer, grinding device, etc. Unlike the aromatic polyamide pulp, which is made into a large amount, it shows a large shrinkage when dried. At this time, since the water-swellable fibrillated fibers and other components are held and dried and contracted, it has excellent binder performance.

  If the water content is 70 wt% or more, it is not limited to the water-swellable fibrillated fiber obtained by the method described above. For example, as described above without intentionally drying in the film or filament manufacturing process Water-swellable fibrillated fibers obtained by performing a fibrillation treatment such as beating may be used.

  Further, as a particle size of the water-swellable fibrillated fiber of the present invention, using a sieving degree tester specified in JIS P-8207, the collection rate of 42 mesh wire mesh is 3 wt% or less and 140 mesh wire mesh. The passing portion needs to be 30 wt% or more, more preferably 50 wt% or more, and further preferably 80 wt% or more. Even when the water content of the water-swelled fibrillated fiber is 70 to 99 wt%, when the 42 mesh wire mesh collection is 3 wt% or more or the 140 mesh wire mesh passage is 30 wt% or less, these are used to form a sheet Even if the product is made, the dispersibility of the water-swelled fibrillated fibers is poor, so that a homogeneous sheet cannot be obtained and sufficient strength cannot be obtained.

  In general, when fibrillated fibers such as pulp or fibril are used as a paper binder, since the entanglement between the fibers becomes important, their contact area, that is, the specific surface area of the fibrillated fibers used as the binder is large. The contribution to the improvement of paper strength is greater. Therefore, the water-swellable fibrillated fiber of the present invention has ultrafine fibrils having a diameter of 100 nm or less in order to increase the contact area between the fibers. Examples of fibrils having a diameter of 100 nm or less include those shown in FIG.

  The water-swellable fibrillated fiber having such fibrils is obtained by further converting a fibril obtained by the method described in WO2004 / 099476, JP-B-35-11851, JP-B-37-5732, etc. It can be obtained by beating, refining with a beater, mill, high-pressure homogenizer, grinding device, etc., or it can also be obtained by classifying a fine size from the aforementioned fibrids using a known classifier. it can. Preferably it is obtained by the former method. However, both may be used in combination as long as they satisfy the requirements of the present invention.

  If the 42-mesh wire mesh collected part of the produced water-swellable fibrillated fiber is 3 wt% or more, or the 140-mesh wire mesh passing part is 30 wt% or less, or if it does not have a fibril diameter of 100 nm or less, the disc refiner is used again. Disintegration and beating can be performed by a papermaking raw material processing apparatus that exerts a mechanical cutting action, such as a beater, a high-pressure homogenizer, and the like.

  Further, the water-swellable fibrillated fiber of the present invention needs to have a water content of 70 to 99 wt%. When the water content is less than 70 wt%, the binder performance based on drying shrinkage is inferior, and sufficient mechanical strength cannot be obtained when added to paper or the like. In addition, when the water content is 99 wt% or more, the handling property is poor because a large amount of water is contained.

  In general, what is called fibrillated fiber is a dispersion of dried short fibers in water again to form fibrils using a refiner, beater, mill, high-pressure homogenizer, grinding device, etc. Even if soaked, most of the water is adsorbed on the fiber surface, and it does not contain moisture inside the fiber structure like water-swelled fibrillated fibers. Therefore, the embedding effect (= binder performance) due to drying shrinkage is poor. .

  On the other hand, when the water-swellable fibrillated fiber of the present invention is dried in a state in which the fibers and other components are entangled with each other when wet, the shrinkage effect at the time of drying due to the release of water inside the fiber, strong binder performance Demonstrate.

Here, the moisture content is calculated by the following equation.
{(Fiber weight when wet)-(Fiber weight when absolutely dry)} / (Fiber weight when wet) * 100

Further, the following method was used to measure the drying shrinkage of the fiber that greatly contributed to the binder performance.
Paper of 100 g / m ² is made by a known wet papermaking method using only the target fiber, and the wet paper sheet area immediately after paper making and the wet paper sheet are calculated from the sheet area after drying under no pressure.
S = [(S1-S2) / S1] × 100
Where S: drying shrinkage (%)
S1: Sheet area of para-aramid fibrid 100 g / m ² in wet paper condition obtained using a TAPPI-type handmade paper making machine
S2: Sheet area after drying for 5 hours at 120 ° C

  Here, in order to use as a binder, the drying shrinkage of the target fiber is preferably 10 to 70%, and more preferably 15 to 50%. When the drying shrinkage rate is less than 10%, the binding force as a binder is insufficient, and when it exceeds 70%, handling becomes difficult.

  In order to make a sheet-like material using the water-swellable fibrillated fiber of the present invention, a known method can be used. For example, after dry blending water-swellable fibrillated fibers and other fiber components, a dry paper making method that uses air current to form a sheet, water-swellable fibrillated fibers and other fiber components are dispersed and mixed in a liquid medium After that, it is discharged onto a net or belt to form a sheet, which is dried by removing the liquid, water-swellable fibrillated fibers and other components as an aqueous slurry, and a mesh wire net or woven or knitted fabric or A spray coating method in which spray coating is performed on a fabric such as a nonwoven fabric and then dried can be applied. In the case of the water-swellable fibrillated fiber of the present invention, a coating method can be preferably applied because it contains a lot of very fine fibril fibers of 140 mesh or more.

  For example, the water-swellable fibrillated fiber of the present invention and the functional filler described later are dispersed in water to form an aqueous slurry. It is preferable to dilute the slurry to an appropriate concentration, coat the substrate with a known spray device, and dry it to form a sheet. The substrate is preferably a fiber structure such as a nonwoven fabric or a woven or knitted fabric, or a mesh wire mesh.

  As a method for adjusting the aqueous slurry, first, a slurry in which a functional filler and a water-swellable fibrillated fiber are dispersed using water as a dispersion medium is prepared. By sufficiently disaggregating using a known stirrer such as a disaggregator, a slurry in which each component is uniformly dispersed can be obtained. In addition, a resin binder component can be added to the slurry for the purpose of improving the adhesion to the substrate within a range that does not impair the effect.

  Other components that can be used for forming sheets include cellulose fibers such as natural cellulose fibers and solvent-spun cellulose fibers, acrylics, polyolefins, polyesters, wholly aromatic polyesters, wholly aromatic polyester amides, polyamides, wholly aromatic polyamides, wholly aromatics. Group polyether, wholly aromatic polycarbonate, wholly aromatic polyazomedin, polyimide, polyamideimide (PAI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), poly-p-phenylenebenzobisoxazole (PBO), polybenzo Single fibers and composite fibers made of resins such as imidazole (PBI), polytetrafluoroethylene (PTFE), polyvinyl alcohol, and ethylene-vinyl alcohol copolymers, Organic fibers such as terriers cellulose, inorganic fibers such as carbon fibers, ceramic fibers, slag wool, glass wool.

  Other components that can be used for sheeting include activated carbon, graphite, carbon black, carbon nanotubes, pigments, titanium, silica, iron, ferrite, gallium, arsenic, sand, earth, soot, barium titanate, titanium photocatalyst, tourmaline. , Mozzanite, coral reef powder, porous silica, xylitol, fluorescent dye resin powder, tea cake powder, chito acid powder, silk powder, various antibacterial agents, gold, silver, copper, platinum, cobalt, hydrogen storage alloys, etc. A functional filler is mentioned. As the particle diameter of the filler, particles of submicron to several tens of μm are easily captured, but are not limited thereto.

The present invention will be specifically described below based on examples. The present invention is not limited to these.
The physical properties of the water-swellable fibrillated fiber were evaluated as follows.
Moisture content:
{(Fiber weight when wet)-(Fiber weight when absolutely dry)} / (Fiber weight when wet) * 100
Calculated according to
Sieving test:
According to JIS P-8207, it carried out as follows.
2.0 g of the target fiber material was collected at an absolute dry weight, and disaggregated at 3000 rpm for 3 minutes using a disaggregator (manufactured by Rikuma Kumagai; standard pulp disintegrator) together with 2.0 L of water, and the solid content concentration was about 0.00. A 2 wt% slurry was made.
Thereafter, a sieving degree tester defined in JIS 8207 (22 product made by Kumagai Riki; the first tank is a 22 mesh wire mesh, the second tank is a 42 mesh wire mesh, the third tank is a 100 mesh wire mesh, and the fourth tank is a 140 mesh wire mesh; ) For 15 minutes.
Further, the solid content collected by each mesh wire net is collected, dried using an oven at 120 ° C. for 12 hours, the weight of the collected content is weighed for each mesh wire mesh, and the input fiber The difference between the weight and the weight of the fiber collected by each mesh wire mesh was taken as the amount of passage through the 140 mesh wire mesh.
Measurement of fiber diameter:
The fiber diameter is measured by dropping a 0.05 wt% dilute slurry onto a sample stage, drying it, conducting the conductive treatment, and expanding it to 30,000 times with a scanning electron microscope (manufactured by JEOL; JSM6330F). By observing the visual field and including fibers of 100 nm or less in three or more fields of view, the target fiber has fibrils with a diameter of 100 nm or less.
In addition, the average content of fibers of 100 nm or less in five fields of view was fractionated as follows.
X: not observed at all Δ: average of less than 10 per field of view ○: average of 10-30 per field of view ◎: average of 30 or more per field of view drying shrinkage:
The procedure was as described above.

[Example 1]
After creating an aqueous dispersion with a solid content concentration of 0.2 wt% of aromatic polyamide fibrid (manufactured by Teijin Twaron, manufactured in accordance with the method of WO2004 / 099476), an existing disc refiner (manufactured by Riki Kumagai; KRK high concentration disc refiner) ) Was used under the treatment conditions of clearance = 0.02 mm and the number of passes = 10, followed by dehydration to obtain water-swellable fibrillated fibers having a water content of 94.3 wt%. The sieving test results are as shown in Table 1.

[Example 2]
10 L of water was added to 100 g of the aromatic polyamide fibrid used in Example 1, and the mixture was sufficiently stirred using a known disintegrator to obtain a slurry having a solid content concentration of about 3.0 wt%. The obtained dispersion was subjected to a homogenizer treatment three times at a pressure of 500 kg / cm ² using a high-pressure homogenizer described in JP-A No. 2003-193387, then dehydrated and a water-swellable fibril having a water content of 88.6 wt%. A modified fiber was obtained. The sieving test results are as shown in Table 1.

[Comparative Example 1]
Aromatic polyamide fibrid (manufactured according to the method of WO2004 / 099476, manufactured by Teijin Toilong) itself was used. The water content was 92.7 wt%. The sieving test results are as shown in Table 1.

[Comparative Example 2]
The water-swellable fibrillated fiber obtained in Example 1 was heat-treated in an oven at 105 ° C. for 10 minutes to obtain a water-swellable fibrillated fiber having a water content of 63.0 wt%. The sieving test results are as shown in Table 1.

[Comparative Example 3]
The same treatment as in Example 2 was performed using an aromatic polyamide fibrillated fiber pulp (Teijin Techno Products, Twaron 1097), which was fibrillated by beating the aromatic polyamide short fibers (manufactured by Teijin Techno Products). 9 wt% of fibrillated fiber was obtained. The sieving test results are as shown in Table 1.

[Comparative Example 4]
A commercially available fine fibrous aramid (manufactured by Daicel Chemical Industries, Tiara) was used as Comparative Example 4. The sieving test results are as shown in Table 1.

[Evaluation results]
The water-swellable fibrillated fiber of Example 1 is obtained by further refinement of the fibril of Comparative Example 1 by further treatment with a disc refiner. As can be seen from the sieving test, the refinement proceeds. In addition, a significant increase in fibrils having a diameter of 100 nm or less, which is important as a binder, was observed.

  The fibrillated fiber of Example 2 is obtained by subjecting Comparative Example 1 to a high-pressure homogenizer treatment, and further refinement is promoted by this treatment, and it can be seen that an increase in fibrils having a diameter of 100 nm or less, which is important as a binder, is observed. . A representative SEM diagram of the obtained fiber is shown in FIG. As is clear from this figure, many fibers having a very small fibril diameter of 100 nm or less were confirmed.

  On the other hand, Comparative Example 1 satisfied the water content and the fibrils with a diameter of 100 nm or less, but the result of the sieving test was inappropriate and there was a problem in dispersibility. An example of the SEM photograph of the fiber is shown in FIG. It can be seen that fibers having a small fibril diameter of 100 nm or less are seen, but those having a small quantity compared to Example 1 and having a large fiber particle diameter are seen.

  In Comparative Example 2, the water-swellable fibrillated fiber of Comparative Example 1 was subjected to a heat treatment to reduce the water content. This heat treatment confirmed an increase in size and a decrease in drying shrinkage, but this was caused by It is conceivable that the moisture inside the fibers is reduced by the heat treatment, and the fibrillated fibers are bound together to form aggregates.

  In Comparative Example 3, high-pressure homogenizer treatment was performed on an aromatic polyamide fibrillated fiber prepared from short fibers having a strong crystal structure, and a representative SEM diagram of the fiber is shown in FIG. Although it was confirmed that the fibers were refined by the high-pressure homogenizer treatment, the drying shrinkage rate, which is important as a binder, was small, and the fibril diameter was clearly large as compared with FIG. , 2 is inferior to 2.

  Comparative Example 4 is the same as Comparative Example 3, and the water-swellable fibrillated fiber of the present invention obtained by introducing an organic polymer solution into an aqueous coagulating solution and coagulating it in a state where shearing such as stirring is applied. Therefore, it can be seen that the drying shrinkage is small and the performance as a binder is inferior to that of Examples 1 and 2.

[Creation of sheet containing fibrillated fiber]
The physical properties of the sheet containing the water-swellable fibrillated fiber of the present invention were evaluated as follows.
Sheet thickness: compliant with JIS P8118 Sheet weight: compliant with JIS P8124 Sheet tensile strength: compliant with JIS P8113

[Example 3]
Aramid obtained by cutting 15 parts by weight of the water-swellable fibrillated fiber obtained in Example 1 and poly (paraphenylene) -copoly (3,4-diphenyl ether) terephthalamide fiber (Technola 0.55 dtex manufactured by Teijin Techno Products) into 6 mm. 85 parts by weight of short fibers and 5000 parts by weight of water were disaggregated at 3000 rpm for 3 minutes using a JIS standard disaggregator to obtain a papermaking slurry. Next, this slurry was made with a TAPPI-type square handsheet machine, press dehydrated, and then dried with a dryer at 120 ° C. for 5 hours to obtain a sheet.

[Example 4]
A sheet-like material was obtained in the same manner as in Example 3, except that the water-swellable fibrillated fiber obtained in Example 2 was used instead of the water-swellable fibrillated fiber obtained in Example 1.

[Comparative Example 5]
A sheet-like material was obtained in the same manner as in Example 3, except that the water-swellable fibrillated fiber of Comparative Example 1 was used instead of the water-swellable fibrillated fiber.

[Comparative Example 6]
A sheet-like material was obtained in the same manner as in Example 3, except that the water-swellable fibrillated fibers obtained in Comparative Example 2 were once dried to reduce the water content instead of the water-swellable fibrillated fibers. It was.

[Comparative Example 7]
A sheet-like material was obtained by the same method except that the fibrillated fiber obtained in Comparative Example 3 was used instead of the water-swellable fibrillated fiber used in Example 3.

[Evaluation results]
In Examples 3 and 4, sheets were formed using the water-swellable fibrillated fibers of Examples 1 and 2, but the tensile strength of the sheet was greatly improved as compared with Comparative Example 1. This is because the contact area of the water-swellable fibrillated fiber is increased as the water-swelled fibrillated fiber is refined, entangled with other component fibers as a binder, shrinkage and adhesion are improved, and the water in the sheet is increased. This is thought to be because the dispersibility of the swellable fibrillated fibers was improved.

  In Comparative Example 5, the tensile strength of the sheet is further reduced as compared with Comparative Example 4. This is thought to be due to the fact that the amount of water present inside the fiber was reduced by heat treatment, resulting in a decrease in drying shrinkage and the aggregation of water-swellable fibrillated fibers, resulting in a deterioration in dispersibility within the sheet.

  In Comparative Example 6, the water-swellable fibrillated fiber of Example 1 was dried once and the water-swelled fibrillated fiber having a water content reduced to 70% or less was used. Is thought to have been reduced. In Comparative Example 7, the short fiber manufacturing process once passes through the drying process, and there is no moisture inside the fiber. Therefore, the drying shrinkage is small and the binder performance is insufficient, so the tensile strength of the sheet is considered to be low.

  Next, spray coating performance evaluation of the aqueous slurry containing the fibrillated fiber of the present invention was performed.

[Spray coating method]
The fibrillated fiber and filler of the present invention are dispersed in water to obtain an aqueous slurry, which is then put into a known spray device, applied onto a substrate and dried to form a coating layer.
The following contents were evaluated.
・ Coating unevenness by visual inspection ・ Thickness of coating layer by SEM observation of cross section ・ Adhesiveness of coating layer by Scotch tape method Adhesive tape with adhesive surface of 15mm width and 120mm length (manufactured by Sumitomo 3M Ltd., trade name "Scotch") After pressing the tape “) against the surface of the coating layer, the adhesive tape is peeled off and the adhesion of the coating material to the adhesive surface is visually determined.

[Example 5]
50 parts by weight of the water-swellable fibrillated fiber obtained in Example 1 and 50 parts by weight of powdered activated carbon (manufactured by Kuraray Chemical Co., Ltd., RP-15 (specific surface area 1250 m ² / g)) and 1000 parts by weight of water The part was wet kneaded using a known mixer to obtain a coating composition.
The obtained coating composition was put into a spray apparatus (Anest Iwata W101), and the substrate to be coated (manufactured by Teijin Techno Products, meta-aramid nonwoven fabric, dimensions: 20) with a spray pressure of 5 kgf / cm ² and a discharge rate of 10 cc / min. × 20 cm, basis weight; 480 g / m ² ). At this time, the formation of a liquid pool on the surface of the substrate was suppressed by arranging the substrate to be coated on white filter paper so that the coating could be performed uniformly. This was sufficiently dried at 120 ° C. × 2 hr with a dryer to obtain a sheet.

[Example 6]
In Example 5, a sheet-like material was obtained in the same manner except that a copper expanded metal (manufactured by Nippon Metal Industry Co., Ltd.) having a thickness of 32 μm (porosity of 57%) was used as the substrate to be coated.

[Comparative Example 8]
A sheet-like material was obtained in the same manner except that the fine fibrous aramid of Comparative Example 4 was used instead of the water-swellable fibrillated fiber used in Example 3.

[Comparative Example 9]
In Example 5, instead of using the water-swellable fibrillated fiber obtained in Example 1, the one used in Comparative Example 1 was used. As a result, the spray nozzle was clogged and could not be coated.

[Evaluation results]
From Examples 5 and 6 and Comparative Example 8, it can be seen that the water-swellable fibrillated fiber of the present invention is uniform, has a strong binder performance and greatly contributes to the adhesion of the coating layer. Furthermore, since the fiber size was too large in Comparative Example 9, a good coating layer could not be obtained.

According to the present invention, since a fibrous binder excellent in heat resistance, chemical stability, and binder function can be provided, a battery / capacitor separator, electrical insulating paper, filter paper, a printed wiring board substrate, a wet friction material It is effective in improving the mechanical, thermal, and chemical properties of high-performance paper represented by paper.
Further, since the coating property is good, it is also effective for forming a battery / capacitor electrode layer.

An example of the water-swellable fibrillated fiber of the present invention. The water-swellable fibrillated fiber of Comparative Example 1. General fibrillated fiber.

Claims (11)

A water-swellable fibrillated fiber comprising an organic polymer, wherein the water-swellable fibrillated fiber is introduced into an aqueous coagulation liquid and subjected to shearing such as stirring. The organic polymer water-containing molded product obtained by coagulation and / or obtained by beating the organic polymer polymer water-containing molded material as a raw material, and satisfying the following requirements Water-swellable fibrillated fiber.
a) In the sieving test, the line spacing is 37 μm, the collection rate of 42 mesh wire mesh is 3 wt% or less, and the line interval is 10 μm and the 140 mesh wire mesh passage is 30 wt% or more.
b) The water content is 70 to 99%.
c) Having fibrils with a fiber diameter of 100 nm or less.   The water-swellable fibrillated fiber according to claim 1, wherein the water-swellable fibrillated fiber is obtained without heating and drying after the coagulation step.   The water-swellable fibrillated fiber according to claim 1, wherein the water-swellable fibrillated fiber has a drying shrinkage of 10% or more.   The water-swellable fibrillated fiber according to any one of claims 1 to 3, wherein the organic polymer is an organic polymer having a carbonization or melting temperature of 300 ° C or higher.   The water-swellable fibrillated fiber according to any one of claims 1 to 4, wherein the organic polymer is an aromatic polyamide.   The water-swellable fibrillated fiber according to claim 1, wherein the beating treatment is at least one method selected from the group consisting of a refiner, a beater, a mill, a high-pressure homogenizer, and a grinding device.   The water-swellable fibrillated fiber according to any one of claims 1 to 6, wherein the fibrillated fiber has a line interval of 10 µm and a 140-mesh wire mesh passage amount of 50 wt% or more in a sieving test.   The water-swellable fibrillated fiber according to any one of claims 1 to 7, wherein the fibrillated fiber has a line interval of 10 µm in a sieving test and a 140 mesh wire mesh passage is 80 wt% or more.   A sheet-like product comprising the water-swellable fibrillated fiber according to claim 1. A water-swellable fibrillated fiber that satisfies the following requirements is made into an aqueous slurry, and spray-coated on a substrate and then dried.
a) In the sieving test, the line spacing is 37 μm, the collection rate of 42 mesh wire mesh is 3 wt% or less, and the line interval is 10 μm and the 140 mesh wire mesh passage is 30 wt% or more.
b) The water content is 70 to 99%.
c) Having fibrils with a fiber diameter of 100 nm or less.   The manufacturing method of the sheet-like material of Claim 10 in which an aqueous slurry contains a functional filler.