TWI482895B - Surface-modified fiber and method of manufacturing the same - Google Patents

Description

Surface modified fiber and manufacturing method thereof

The present invention relates to a high-strength fiber whose surface has been modified and a method for producing the same, and more particularly to a surface-modified fiber and a method for producing the same, which have good adhesion to a resin and are suitable as materials for composite materials. .

High-strength, high-elasticity fibers of so-called super fibers have been widely used as reinforcing fibers for prepregs and FRP. In order to reflect the physical properties of the reinforcing fiber to the physical properties such as FRP, the adhesion to the resin is important. If the adhesion is low, the interface becomes a defect, and the mechanical properties of the reinforcing fiber cannot be reflected to the FRP. Wait for the physical properties. Therefore, various developments have been made as the performance of the reinforcing fiber is developed and the adhesion is required to be improved.

For example, polybenzazole (PBZ) fiber has twice the strength and elastic modulus of polyparaphenylene terephthalamide fiber represented by the special fiber currently marketed, and is expected to be a special grade for the next generation. Fiber, in addition, among the PBZ fibers, polyparaphenylene benzobis The azole (PBO) fiber has the highest modulus of elasticity (for example, refer to Patent Document 1).

In addition, as a result of the improvement of the performance of the fiber, there has been proposed a laminate improvement, for example, a fiber which imparts a functional group capable of adhesion to the surface of the fiber by corona treatment (for example, see Patent Document 2). However, in the corona treatment, since the functional group is not sufficiently imparted to the surface due to low energy, the adhesiveness that can be satisfied has not been obtained. Therefore, in order to impart more functional groups, investigations have been conducted on higher-temperature atmospheric piezoelectric slurry treatment (for example, refer to Patent Document 3).

However, even if the functional group is imparted by the atmospheric piezoelectric slurry treatment, the satisfactory adhesion is not obtained. Therefore, it has been proposed to impart a functional group to the surface and also to impart fine unevenness to the surface of the fiber (for example, refer to Patent Document 4). However, even such a surface-modified fiber has not yet obtained the adhesiveness that allows the mechanical properties of the PBO fiber to be sufficiently exhibited.

Patent Document 1: US Patent No. 5296185

Patent Document 2: Japanese Patent Laid-Open No. Hei 7-102473

Patent Document 3: Japanese Patent Laid-Open Publication No. 2003-221778

Patent Document 4: Japanese Patent Laid-Open Publication No. 2003-201625

The present invention has been made in view of the above-described state of the art, and an object thereof is to provide a high-strength surface-modified fiber having excellent adhesion and a method for producing the same, which is to reflect the excellent mechanical properties of the reinforcing fiber to physical properties such as FRP.

The present inventors have finally completed the present invention as a result of intensive studies in order to achieve the above object.

That is, the first invention of the present invention is a fiber having a fiber having a strength of 8 cN/dtex or more, which is characterized by an atomic force microscopic observation of the fiber in the longitudinal direction of the fiber 4 μm × the short axis of the fiber. square In the area of 2 μm, there are 20 or more crack-like recesses extending in the short-axis direction of the fiber by 0.1 μm or more and having a depth of 10 to 100 nm.

Preferred forms of the fibers of the present invention are as follows:

(1) The surface roughness Ra of the surface uneven structure in the average cross-sectional profile is 1.5 to 6.0 nm.

(2) From the interatomic force microscope on the surface of the fiber, the longitudinal direction of the fiber in the field of view is 4 μm × 2 μm in the short axis direction of the fiber, and three sections are cut out arbitrarily. The height difference of the height of the section passing through the center of the convex part is 20~ 100nm.

Further, the second invention of the present invention is a production method characterized in that an ion beam is irradiated onto a surface of the fiber for treatment.

Further, preferred embodiments of the method for producing a fiber of the present invention are as follows:

(1) The treatment gas of the ion beam is oxygen, air, nitrogen, argon or a mixed gas thereof.

(2) The ion beam energy of the ion beam treatment is set to 10 ^-2 to 10 ⁰ KeV, the treatment pressure is 0.1 to 1.0 Pa, the treatment power is 50 to 5000 W, and the fiber transportation speed is 0.01 to 1 m/min. deal with.

The fiber of the present invention has a high surface structure as compared with the conventional surface-treated fiber, and has a high adhesion to the resin. Further, since the fiber of the present invention improves the adhesion according to the specificity of the surface shape, the phase property of the resin and the fiber is not obtained, and high adhesion can be obtained. In addition, the fiber of the present invention is irradiated by an ion beam The surface modified fiber can be easily obtained by hitting the surface of the fiber.

Hereinafter, the fiber of the present invention and a method for producing the same will be described in detail.

(fiber)

The fiber system of the present invention must have a strength of 8 cN/dtex or more. This is because if the fiber is of such strength, the fiber properties can be sufficiently reflected to the composite material such as FRP. Although the upper limit of the fiber strength does not become a particular problem, if it exceeds 70 cN/dtex, even if it has the surface structure of the fiber of the present invention, it is difficult to sufficiently reflect the fiber properties to the composite material.

Examples of the fiber having such a strength include high molecular weight polyethylene fibers having particularly high strength. The fiber-based monofilament fiber of the present invention preferably has a diameter of 8 to 15 μm. This is because, if it is such a fiber diameter, a sufficient surface area is provided, and a plurality of the surface uneven structures can be provided. On the other hand, the strength reduction due to the uneven portion is small. More preferably, the monofilament fiber has a diameter of 9 to 13 μm, and more preferably 10 to 12 μm.

The fiber of the present invention is characterized in that the fiber-like surface of the fiber has an area of 4 μm in the longitudinal direction of the fiber and 2 μm in the short axis direction of the fiber in the field of view of the fiber surface, and a crack-like recess having a depth of 10 to 100 nm is extended by 0.1 μm or more. More than 20. The short axis direction of the fiber is a direction perpendicular to the longitudinal direction of the fiber. When the concave portion in the surface uneven structure observed in the conventional fiber has a circular shape, the fiber of the present invention has a crack shape in a direction approximately perpendicular to the fiber axis, so that the surface is inhibited from shearing and exhibits excellent adhesion. Preferably, the crack-like recess is 30 in the above area. More preferably, there are 35 or more and 100 or less. It is considered that when the depth of the crack-like recess is less than 10 nm, the improvement in resin adhesion cannot be expected too much; if it exceeds 100 nm, the surface of the fiber is easily broken.

The fiber of the present invention has a surface uneven structure in an average cross-sectional profile, and the surface roughness Ra is preferably from 1.5 to 6.0 nm. Ra is more preferably 2.0 nm or more, still more preferably 2.5 nm or more. When Ra is in this range, the influence on the reduction in physical properties of the fiber is small, and on the other hand, an excellent anchoring effect can be exhibited. Further, it is also possible to form a convex portion having a large width and a strong shear on the surface.

The fiber of the present invention is observed by an atomic force microscope on the surface of the fiber, and the longitudinal direction of the fiber is 4 μm × 2 μm in the short axis direction of the fiber, and three cross sections are arbitrarily cut out, and the height difference of the height of the cross section passing through the center of the convex portion is compared. Good is 20nm~100nm. The height difference is more preferably 30 nm or more, and still more preferably 40 nm or more. The height difference in the present invention means the height difference between the valley and the apex of the convex portion of the surface uneven structure. When the height difference is within this range, the influence on the reduction in fiber physical properties is small, and on the other hand, an excellent anchoring effect can be exhibited.

(Production method)

Further, in the method for producing a fiber of the present invention, for example, it is preferable to form a surface uneven structure by irradiating an ion beam on a surface thereof by using a fiber having a strength of 8 cN/dtex or more. In the case of using a plasma treatment, a high-frequency sputtering treatment, or the like, when the irradiation time and the irradiation energy are increased, the concave portion itself is started to be reduced, and it becomes difficult to obtain the fiber of the present invention. Although the reason why the convex portion or the crack-like concave portion having a large height difference can be obtained by irradiating the ion beam is not determined, it is presumed that since the ion beam has directivity at the ion velocity, the height difference can be effectively obtained. Convex.

In order to perform ion beam treatment on the fiber, after spinning or heat treatment, a roll-to-roll method may be used to perform roll-to-roll, and a continuous roll-to-roll process may be performed by using an ion beam processing apparatus, or The batch method is preferably a roll-to-roll method based on the viewpoint of operability. In addition to cellulose, the treated object may also be a fabric that is untwisted into monofilament fibers and made unidirectional. As the ion gun for irradiating the ion beam to the fiber, for example, a closed drift ion source manufactured by Kauffman can be used, and the ion source can utilize DC discharge, RF discharge, microwave discharge, or the like. In particular, in the roll-to-roll process, a linear ion source is preferably used.

The gas used in the ion gun is not limited as long as it can generate ionic particles, for example, from hydrogen, helium, oxygen, nitrogen, air, fluorine, helium, argon, neon or N ₂ O. The mixture is appropriately selected and used. Among these gases, in particular, when oxygen or air forms the above-mentioned convex portion on the surface of the fiber, it is preferable to impart a functional group.

The type and intensity of the ion beam irradiated on the fiber can be modified to the above range, and is not particularly limited. Usually, the energy of the ion particles constituting the ion beam is appropriately selected from the discharge voltage and discharge of the ion gun. current, discharge power, gas beam (beam gas) flow rate was adjusted to about 10 ^-2 ~ l0 ⁰ KeV, that adjusts the discharge voltage to approximately 295 ~ 800W, discharge current system was adjusted to be about 0.1 ~ 10A and irradiation. Preferably, the irradiation is carried out by adjusting the pressure to about 0.1 to 1.0 Pa at the time of treatment and adjusting the fiber transportation speed to about 0.01 to 0.3 m/min.

(adjustment method of follow-up)

The adhesion evaluation method of fiber and resin generally adopts a droplet method or an ILSS method. The droplet method is a method of evaluating the stress when the fiber is extracted from the resin bead, and since the resin bead of a uniform shape is difficult to obtain, there is a problem of accuracy and efficiency. On the other hand, the ILSS method is a method of evaluating the interfacial shear stress when a shear stress is applied to a resin sheet embedded with a fiber by a 4-point bending test, and is easily subjected to the strength characteristics of the resin or the fiber. Impact, accuracy is low.

In the evaluation of the adhesion to the fiber resin of the present invention, a method of evaluating the attenuation of the fiber tensile stress when the fiber is embedded in the resin and the fiber is extracted is used. In this evaluation method, a test piece having a certain shape can be obtained, and further, the influence of the material strength characteristics is small, and evaluation of high precision and high efficiency is possible.

Fig. 1 is a view schematically showing a method of producing a test piece. Specifically, the following methods are used:

(a) Two slits of a depth of 12 mm, a width of 5 mm, and a thickness of 3 mm, which are opposed to each other, were placed on a 20 cm square pedestal by using a single-sided blade to cut a slit 2 having a depth of 0.05 to 0.1 mm. The susceptor is preferably a glass plate, but is not particularly limited as long as it is flat and can withstand heating at 60 °C.

(b) Next, the monofilament is unwound from the yarn, the fibers are laid across the embedded plate, and the slits are sandwiched and fixed. In this case, the length of one side of the monofilament fiber 1 outside the resin is 15 to 20 cm, and the both ends of the fiber are fixed to the base by the adhesive tape so that the monofilament fiber 1 does not relax. Form 4).

(c) Next, a substrate of 62 cc/100 cc of a thermosetting epoxy resin (LUVEAK 812) and a curing agent (LUVEAK DDSA) were mixed and stored in a refrigerator, and returned to normal temperature in a desiccator. Using a glass rod having a diameter of 4 mm, 10 drops of a hardening accelerator (LUVEAK-DMP30) was added, and while the bubbles were not allowed to enter, the mixture was stirred for 1 minute. The shelf life of the blending solution is set to 1 month. The resin liquid 3 was poured into the embedded plate, and the amount was adjusted so as to be about 0.5 mm from the embedded plate. The adhesive tape was removed and hardened in an oven at 60 ° C for 12 hours.

(d) After cooling at room temperature, it is noted that the monofilament fiber 1 is not broken, and the resin sheet is taken out from the embedded plate to obtain a test piece composed of the resin 5 and the monofilament fiber 1. A sheet of 3 x 2 cm was bent by sandwiching the fibers at one end of the monofilament fiber 1 outside the resin, and fixed by an adhesive.

Fig. 2 is a view schematically showing a method of measuring stress distribution using Raman scattering.

The test piece was mounted on a sample rack for micro-Raman scattering measurement, and the monofilament fiber 1 outside the resin was placed on a roller attached to the end of the sample stage, and the test piece was fixed by a stopper. A load (6) 15 gf was placed on a sheet of monofilament fiber 1 attached to the resin, and Raman of the monofilament fiber 1 in the resin was measured along the fiber axis by micro Raman scattering at intervals of 10 μm. scattering. Since the wave number of the Raman scattering is determined by the extraneous stress 7 of the molecule, the applied stress line 7 can be used to obtain the applied stress 7 from the wave number of the Raman scattering.

Fig. 3 is a view schematically showing the stress distribution in the above adhesion evaluation method.

In the resin, since the monofilament fiber 1 is supported by the resin, the tensile stress applied to the fiber is more attenuated toward the inside of the resin. That is, the stress distribution as observed as a function of the distance along the fiber axis can be obtained. If the applied stress is increased, the interface will fall from the position where the fiber enters the resin, and as the applied stress becomes larger, the interface relief region will expand. The interface drop zone is different from the fully follow zone.

If the adhesion is good, the complete adhesion region is wide, and further, the critical value of the stress at which the interface is lowered is large. Therefore, it is possible to evaluate the adhesion by using the distance along the fiber axis, the interface drop point (X _c ) and the stress, and the interface fall stress (σ _c ) in the inflection point of the stress distribution region of the interface relief region and the completely adjacent region. .

Fig. 4 is a view schematically showing the above-described standard judgment method of the interface strength.

With regard to the fiber of the present invention, as a method for judging the interface strength standard in the composite material with the resin, a method of determining the presence or absence of the interface declination region when imparting a certain skew to the composite material can be employed. In other words, the test piece which is completely embedded so that the long axis direction of the PBZ monofilament fiber of 2 to 3 mm and the rectangular resin are parallel to each other is applied with a constant skew in the direction of the long axis. In the state where the skew is applied, the stress of the fiber is measured by the impedance strain gauge 8 in accordance with Raman scattering, and the presence or absence of the interface relief region is confirmed by the stress distribution with respect to the fiber axis.

First, the fiber of the present invention has an interface fluctuating stress (σ _c by the number of the crack-like recesses, the surface roughness Ra of the surface uneven structure in the average cross-sectional profile, and the height difference of the surface concavo-convex structure as described above. ) is 1.2GPa or more, and the interface drop point (X _c ) is 0.1 mm or less. In the above-described standard method for judging the interface strength, when the resin is an epoxy resin and the skew is 0.8%, the interface does not fall, and the interface can be obtained. A practical composite material that is highly reliable. The range of the interface lodging stress is preferably 1.5 GPa or more, more preferably 1.7 GPa or more, and the range of the interface drop point is preferably 0.09 mm or less, more preferably 0.08 mm or less.

Example

Hereinafter, the present invention will be described in further detail by way of examples, which are not limited by these examples. Also, the evaluation of various characteristics uses the following methods:

(1) Tensile strength

After placing the fiber in a test chamber of a standard state (temperature: 20 ± 2 ° C, relative humidity (RH) 65 ± 2%) for 24 hours or more, a tensile tester was used in accordance with JIS-L-1013 to measure the tensile strength of the fiber. .

(2) Surface roughness Ra

The uneven structure of the fiber surface was evaluated using an atomic force microscope (AFM). AFM uses the SPA300 of SII NanoTechnology AG (SII). The AFM probe uses a DF-40P sold by SII to limit the use of new probes. The scanner uses the FS-20A. In addition, the number of imaging pixels is set to 520 pixels × 256 pixels. Before the observation, the position at which the AFM probe was brought into contact with the surface of the sample was set to be near the center of the short-axis direction of the fiber, and the scanning direction was set to be parallel to the long axis of the fiber. The observation visual field range was set to (fiber longitudinal axis direction) × (fiber short axis direction) = 4 μm × 2 μm. The observation field of view was cut out into 300 sections, and the obtained surface roughness Ra of the averaged pixels of the sections was analyzed by the average profile function. The average value of the Ra values in the five observation fields cut out by the random method obtained by this method was defined as the surface roughness Ra.

(3) Height difference

The uneven structure of the fiber surface was evaluated using an atomic force microscope (AFM). AFM uses the SPA300 of SII NanoTechnology AG (SII). The AFM probe uses a DF-40P sold by SII to limit the use of new probes. The scanner uses the FS-20A. Before the observation, the position at which the AFM probe was brought into contact with the surface of the sample was set to be near the center of the short-axis direction of the fiber, and the scanning direction was set to be parallel to the long axis of the fiber. The observation visual field range was set to (fiber longitudinal axis direction) × (fiber short axis direction) = 4 μm × 2 μm. Three sections are cut out arbitrarily from the observation field, and the height average of the section passing through the center of the protrusion is set as the height difference.

(4) The number of crack-like recesses

The uneven structure of the fiber surface was evaluated using an atomic force microscope (AFM). AFM uses SII NanoTechnology AG (SII) SPA300. The AFM probe uses a DF-40P sold by SII to limit the use of new probes. The scanner uses the FS-20A. Before the observation, the position at which the AFM probe was brought into contact with the surface of the sample was set to be near the center of the short-axis direction of the fiber, and the scanning direction was set to be parallel to the long axis of the fiber. The observation visual field range was set to (fiber longitudinal axis direction) × (fiber short axis direction) = 4 μm × 2 μm. The observed image was analyzed using a Scanning Probe Image Processor manufactured by Image Metrology A/S. The cross section was cut at intervals of 0.02 μm parallel to the longitudinal direction of the fiber, and the cross section was cut out. The concave portion extending 0.1 μm or more in the short axis direction of the fiber was defined as a crack-like concave portion, and the number of observation visual field ranges of 4 μm × 2 μm was measured.

(5) Raman scattering measurement

The Raman scattering spectrum was measured by the following method. The Raman measuring device (beam splitter) was measured using a System 1000 from Renishaw. The light source is a 氦-氖 laser (wavelength 633 nm). The test piece of the fiber and the resin was placed on a sample rack for micro-Raman scattering measurement, and the fiber outside the resin was placed on a roller attached to the end of the sample stage, and the test piece was fixed by a stopper. A load of 15 g was placed on a sheet of fibers attached to the resin, and Raman scattering of the fibers in the resin was measured along the fiber axis by micro-Raman scattering at intervals of 10 μm. The Raman measurement is based on the static mode (Static Mode) for the measurement range 970~1810 (cm ^-1 ), the cumulative number of times: 64 times, the exposure time: 1 second, the laser intensity: 1, 10, 25, 50, The optimum intensity among 100%. The peak used for the analysis is a band of 1619 cm ^{-1 to} which the stretching vibration of the aromatic ring belongs. Since the turbulence of the baseline is large and the shape of the peak is skewed, the curve fit using the Gaussian function is not used, and the peak shape is determined by visually determining the peak shape. Using the Raman band wave number and the tensile stress trace line, the fiber is subjected to stress addition from the obtained Raman band frequency to obtain a stress distribution with respect to the distance along the fiber axis. Draw an approximate line of the resulting stress distribution and determine the inflection point of the fully-remaining region and the interface relief region. The distance along the fiber axis at the inflection point is defined as the interface drop point X _c and the stress is the interface fall stress σc.

(Examples 1 to 4)

As the fiber to be treated, Zylon (registered trademark) HM (Example 1), Zylon (registered trademark) AS (Example 2), and Dyneema (registered trademark) SK60 (Example 3) manufactured by Toyobo Co., Ltd. are used. And Kevlar (registered trademark) 29 manufactured by Toray Dupont (Example 4). The fibers were unwound from the fiber bundle into monofilament fibers, and they were arranged on the polyimide film at intervals, and were attached by using a polyimide tape. In the vacuum chamber, oxygen ions were irradiated onto the film by an ion gun while the roller was being advanced, and the surface of the fiber was treated. The ion beam processing apparatus is a roll-to-roll type device that moves a film from a roll to a take-out chamber, a sputtering chamber, a preliminary chamber, and a take-up chamber while performing surface treatment in sequence, and then is rolled by a roll. take.

The chambers are roughly separated by slits. In the ion gun chamber, the film is contacted with a cooling roll and cooled by the temperature of the cooling roll (-5 ° C) to use a wide-width ion gun in such a manner that the roll width direction is uniformly ionized. The ion gun system uses 38CMLIS from Advanced Energy Industries. As a gas system introduced into the ion gun, oxygen was used to irradiate ions from a position of 4 cm from the film and the fiber at a discharge voltage of 540 V, a discharge current of 0.56 A, a discharge electric power of 295 W, a beam gas flow rate of 45 sccm, and a treatment pressure of 3 × 10 ^-1 Pa. bundle. The film was used in a width of 250 mm, and the roller conveying speed was set to 0.05 m/min. Oxygen is not introduced from outside the ion gun. The details and evaluation results of the fibers obtained in Examples 1 to 4 are shown in Table 1.

(Examples 5 and 6)

As the fiber to be treated, Zylon (registered trademark) HM (Example 5) and Zylon (registered trademark) AS (Example 6) manufactured by Toyobo Co., Ltd. were used. In order to reduce the energy per unit area, ion beam treatment was carried out in the same manner as in Examples 1 to 4 except that the roll transport speed was set to 0.25 m/min. The details of the fibers obtained in Examples 5 and 6 and the evaluation results are shown in Table 1.

(Comparative Example 1)

Zylon (registered trademark) AS manufactured by Toyobo Co., Ltd. was used as the fiber to be treated, but ion beam treatment was not performed. The details of the fibers obtained in Comparative Example 1 and the evaluation results are shown in Table 1.

(Comparative Examples 2 to 5) Zylon (registered trademark) HM (Comparative Example 3), Zylon (registered trademark) AS (Comparative Example 2, 6), and Dyneema (registered trademark) SK60 (Comparative Example 5) of Toyobo Co., Ltd. ), and Kevlar (registered trademark) 29 manufactured by Toray Dupont (Comparative Example 4). These fibers were unwound from a fiber bundle into monofilament fibers, and placed in a frame of a PE film of A4 size (frame width: 2 cm) at intervals, and attached by using a polyimide tape. The film frame was placed between two plasma generating electrodes, subjected to oxygen ion beam irradiation, and the surface of the fiber was treated by vacuum plasma. The treatment was carried out at a discharge electric power of 3000 W, a gas flow rate of 5000 sccm, and a treatment pressure of 400 mTorr. The details and evaluation results of the fibers obtained in Comparative Examples 2 to 5 are shown in Table 1.

(Comparative Example 6) A vacuum plasma treatment was carried out by the same method as Comparative Examples 2 to 5 except that Zylon (registered trademark) AS manufactured by Toyobo Co., Ltd. was used, and the fiber transport speed was set to 0.01 m/min. The details of the fibers obtained in Comparative Example 6 and the evaluation results are shown in Table 1.

Industrial use possibility

Since the surface-modified fiber of the present invention has practical adhesion as a composite material, the high elastic modulus of the fiber can be sufficiently exhibited in the composite material. For example, the high-density high-performance circuit board (core substrate) used for packaging the germanium wafer can of course be used for tension members such as cables, wires, or optical fibers; tension materials such as ropes; rocket insulation materials, rocket casings. Impact-resistant members such as air vessels, space materials, and elastic-resistant materials such as pressure vessels, space ropes, planetary probe balloons, etc.; cutting-resistant members such as gloves; fire-fighting clothes, heat-resistant felts, factory gaskets, and heat-resistant fabrics , heat-resistant and flame-resistant members of various sealing materials, heat-resistant cushions, filters, etc.; rubber reinforcing agents for belts, tires, soles, ropes, water pipes, etc.; fishing line, fishing rod, tennis racket, table racket, badminton racket, golf club , golf club head, gut, string, thick canvas, running shoes, marathon shoes, spike shoes, skates, basketball shoes, volleyball shoes, etc.; athletic (walking) bicycles and their wheels, road cars, Racing, off-road vehicles, composite wheels, disc wheels, tension discs, spokes, brake lines, transmission lines, competitive (walking) wheelchairs and their wheels, protective gear, racing suits Sports relations materials such as snow boots, ski poles, safety helmets, parachutes, etc.; friction resistant materials for textile belts for avance belts and clutches; reinforcing materials for various building materials and other knight clothing, speaker cones, weight A wide range of uses such as light strollers, lightweight wheelchairs, lightweight nursing beds, lifebuoys, and life jackets.

1. . . Monofilament fiber

2. . . Slit

3. . . Thermosetting epoxy resin

4. . .矽Rubber frame

5. . . Resin

6. . . Load

7. . . Applied stress

8. . . Impedance strain gauge

Fig. 1 is a view schematically showing a test piece preparation method in the adhesion evaluation method using Raman scattering used in the present invention.

Fig. 2 is a view schematically showing a method of measuring the stress distribution in the adhesion evaluation method using Raman scattering used in the present invention.

Fig. 3 is a view schematically showing the stress distribution and the adhesion evaluation index in the adhesion evaluation method using Raman scattering employed in the present invention.

Fig. 4 is a schematic view showing a test piece used in the present invention for the standard judgment method of the interface strength.

Claims (6)

A fiber having a strength of 8 cN/dtex or more, which is characterized by an atomic force microscopic observation of a fiber surface having an area of 4 μm in the longitudinal direction of the fiber and 2 μm in the short axis direction of the fiber in the field of view of the fiber, extending in the short axis direction of the fiber. There are 20 or more crack-like recesses having a depth of 10 to 100 nm of 0.1 μm or more. The fiber of the first aspect of the patent application, wherein the surface roughness Ra of the surface relief structure in the average cross-sectional profile is 1.5 to 6.0 nm. For example, in the fiber of the first aspect of the patent application, the direction of the fiber in the field of view is 4 μm in the longitudinal direction of the fiber from the surface of the fiber, and the short axis direction of the fiber is 2 μm, and three sections are cut out arbitrarily, and the height of the section passing through the center of the convex portion is obtained. The difference between the average values is 20 to 100 nm. A method for producing a fiber, which is characterized in that the surface of the fiber according to any one of claims 1 to 3 is irradiated with an ion beam for treatment. The method for producing a fiber according to claim 4, wherein the treatment gas of the ion beam is oxygen, air, nitrogen, argon or a mixed gas thereof. The method for producing a fiber according to claim 5, wherein the ion beam energy of the ion beam treatment is 10 ^-2 to 10 ⁰ KeV, the treatment pressure is 0.1 to 1.0 Pa, and the treatment power is 50 to 5000 W. The fiber transport speed was set to 0.01 to 1 m/min for processing.