JP2013032487A - Reinforced fibrous base material and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base material for high performance composite material which can achieve morphological stability by preventing fiber slippage and fray of reinforced fibrous base material, and also has excellent mechanical characteristics and heat resistance of FRP, and to provide its manufacturing method.SOLUTION: The adopted technical method includes forming a reinforced fibrous sheet base S by arranging a plurality of reinforced fiber thread lines 1 in parallel, and making them contact with a low melting point thermoplastic polymer P while maintaining the orientation of these reinforced fiber thread lines 1 and further includes heating the reinforced fiber sheet base S for melting, to a temperature higher than the melting point of the low melting point thermoplastic polymer P, bonding the reinforced fiber thread lines 1 to each other, or bonding reinforced fiber threads to supplementary yarns with the low melting point thermoplastic polymer P, to obtain a stabilized sheet form, and then irradiating with ionizing radiation the reinforced fiber sheet base S to increase the melting temperature of the low melting point thermoplastic polymer P.

Description

  The present invention is an improvement of a reinforced fiber base material, more specifically, can prevent misalignment and fraying of the reinforced fiber base material, and can have form stability, and is excellent in mechanical properties and heat resistance of FRP. The present invention relates to a reinforcing fiber base and a method for producing the same.

  A fiber reinforced plastic (hereinafter referred to as FRP) obtained by laminating a reinforced fiber sheet base material, impregnating with a resin, and curing it is known as a material that is lightweight and has excellent mechanical properties. Various approaches have been made to improve the handleability as much as possible before obtaining an FRP molded product and to improve the appearance and mechanical properties of the resulting FRP.

  Conventionally, <Patent Document 1> proposes a method in which warp yarns and weft yarns are bonded to each other by heat fusion of a thermoplastic polymer in order to prevent structural collapse or fraying of the reinforcing fiber fabric. Has been.

  Moreover, in <patent document 2>, in order to provide the unidirectional form stability of the reinforcing fiber, what is struck with a low melting point thermoplastic resin is proposed.

  In <Patent Document 3>, the problem of fabric misalignment when laminating multiaxial stitched fabrics or installing them in a mold is used to identify the gap between layers of low-melting polymer yarns used for stitch yarns. There has been proposed a multi-axis stitched fabric that can be bonded and integrated to prevent fabric misalignment by heat-sealing.

  These reinforcing fiber sheet base materials have good shape stability, excellent handling properties, are good base materials for laminating work and preform production, and are excellent in mechanical properties of the resulting FRP. The heat-sealing polymer used for sealing these base materials includes the workability of raising and lowering temperature, the melting point of the auxiliary insertion yarn, the convenience of kogation during production, and the sizing agent used for reinforcing fibers. In consideration of deterioration, a low melting point polymer having a melting point of about 80 to 180 ° C. is often used.

  The FRP produced by incorporating a base material in which a low-melting-point polymer is used as a part of the reinforcing fiber base material as described above is a low-melting point that reaches the melting point in the FRP when exposed to a high temperature environment. There is a possibility that the polymer melts and elutes from the FRP cross section. In such a case, the portion where the low melting point polymer is present becomes voids (bubbles), so that the mechanical properties at high temperature are lowered and the heat resistance is high. FRP could not be obtained.

  This is because when a normal low melting point polymer is heated, it becomes a low viscosity state immediately after exceeding the melting point (the melting point and melting temperature of the polymer are substantially the same). In this specification, the temperature at which the solid polymer begins to melt and become liquid is defined as the “melting point”, and when the temperature is raised under predetermined conditions (detailed in the examples) in the DMA measurement used for viscoelasticity measurement. The temperature at which the storage elastic modulus E ′ of the polymer is 100 Pa or less is defined as “melting temperature”.

  In addition, the voids formed by the elution of the low melting point polymer remain as it is even after cooling from a high temperature environment to room temperature, so that the mechanical properties of the FRP itself are greatly lost. There was a problem that the use to is avoided.

  For example, when molding FRP for aircraft use, a resin of 180 ° C. curing type is usually used, but when a base material bonded with a low melting point polymer having a melting point of about 80 to 180 ° C. is used, Since the substrate temperature becomes higher than the melting point of the low-melting polymer, it melts and the morphological stability of the substrate is lost. That is, there is a problem that the orientation direction of the reinforcing fibers is disturbed until the resin is cured, and the mechanical characteristics are lowered.

  In addition, if the melting point of the low melting point polymer used is lower than the heat resistant temperature of FRP usually obtained by using a 180 ° C. type resin, the mechanical properties deteriorate due to the elution of the low melting point polymer described above. There was a problem that it had only heat resistance up to the melting point of the low melting point polymer, and it was not possible to advance for aircraft parts.

  Moreover, in <patent documents 1-3>, although low melting point nylon is employ | adopted as one of the low melting point polymers to stop, water absorption is more than polyester etc. which are used for auxiliary materials, such as a sheet | seat for holding and a net | network. Therefore, when FRP is molded from a reinforced fiber base material using this low melting point nylon, the resin is not sufficiently cured by moisture, or microcracks are generated due to repeated freezing of moisture in the molded product. However, there is a problem that it cannot be a reliable material, and it is not suitable for an aircraft.

  Furthermore, when a so-called “wet prepreg” is produced by using a reinforcing fiber base material using low-melting nylon as described above, dipping in a resin layer and impregnating the resin, followed by a drying step, the resin viscosity In order to improve the impregnation property by lowering the thickness, the organic solvent may be diluted with an organic solvent. However, there is a problem that the low melting point nylon is melted by the organic solvent.

  That is, when the low-melting nylon is melted, the sealing effect is lost, the surface tension of the low-viscosity resin converges the reinforcing fiber bundle into a mesh shape, the tension applied to the reinforcing fiber base, There is a problem that the reinforcing fiber orientation direction of the reinforcing fiber base is shifted due to friction with the guide roller in the middle of the process, or wrinkles occur, and improvement is desired.

JP 10-317250 A Japanese Patent No. 4167842 Japanese Patent Laid-Open No. 2002-227068

  The present invention has been made in view of the above-mentioned problems in the conventional reinforcing fiber base material, and its purpose is to prevent misalignment and fraying of the reinforcing fiber base material. An object of the present invention is to provide a reinforced fiber base material that can have form stability and is excellent in mechanical properties and heat resistance of FRP, and a method for producing the same.

  Means employed by the present inventor for solving the above technical problem will be described with reference to the accompanying drawings.

That is, the present invention arranges a plurality of reinforcing fiber yarns (1...) In parallel, and maintains the orientation of these reinforcing fiber yarns (1. ) In contact with each other to form a sheet-like reinforcing fiber sheet substrate (S),
This reinforcing fiber sheet substrate (S) is heated and melted to a temperature equal to or higher than the melting point of the low-melting point thermoplastic polymer (P), and the reinforcing fiber yarns (1.1) or the reinforcing fiber yarns and auxiliary yarns After adhering with the low melting point thermoplastic polymer (P) and stabilizing the sheet form,
By adopting the technical means of irradiating the reinforcing fiber sheet substrate (S) with ionizing radiation and increasing the melting temperature of the low melting point thermoplastic polymer (P), Completed.

  Moreover, in order to solve the said subject, in addition to the said means, this invention employ | adopts the technical means of irradiating the reinforcing fiber sheet base material S with the unit irradiation amount of ionizing radiation several times. can do.

Furthermore, in order to solve the above-mentioned problems, the present invention adds the reinforcing fiber yarns 1, 1. -While maintaining the orientation of 1 ..., the low-melting point thermoplastic polymer P is brought into contact with each other to form a sheet-like reinforcing fiber sheet substrate S,
A technical means of adhering the reinforcing fiber yarn 1 and the auxiliary insertion yarn 2 with the low-melting point thermoplastic polymer P can be employed.

Furthermore, in order to solve the above-described problems, the present invention provides ionizing radiation as an electron beam in addition to the above means as necessary.

A technical means of irradiation with an acceleration voltage E satisfying the above can be adopted.

  Furthermore, in order to solve the above-mentioned problems, the present invention provides an auxiliary insertion yarn 2 to which a yarn made of a low-melting point thermoplastic polymer P or a low-melting point thermoplastic polymer yarn is attached, in addition to the above-described means, if necessary. It is possible to employ a technical means of forming a knitted or woven fabric structure by contacting the reinforcing fiber yarns 1 arranged at least in the warp direction.

  Furthermore, in order to solve the above-mentioned problems, the present invention provides the reinforcing fiber yarn 1 on the sheet-like net material 4 to which the low-melting point thermoplastic polymer P is adhered in addition to the above means as necessary. It is possible to adopt a technical means of arranging in parallel in the vertical direction and heating and then adhering to the net material 4.

Furthermore, in order to solve the above-mentioned problems, the present invention provides a plurality of reinforcing fiber sheet substrates S in which reinforcing fiber yarns 1.1 are aligned in parallel in addition to the above means as necessary. While reinforcing fiber yarns 1 of each reinforcing fiber sheet substrate S are laminated at different angles and bonded and integrated by multi-axis stitching means to form a laminated substrate LS,
The technical means of disposing the low-melting point thermoplastic polymer P in at least one side of the outermost layer of the sheet in the form of a yarn or a fabric or powder can be employed.

  Furthermore, in order to solve the above-mentioned problems, the present invention makes the low melting thermoplastic polymer P a copolymer having a melting point of 80 to 180 ° C. in addition to the above means as necessary, and reduces the substrate weight to 0. It is possible to adopt a technical means of containing 5 to 10%.

  Furthermore, in order to solve the above-mentioned problems, the present invention provides, in addition to the above-described means as necessary, reinforcing fibers of the reinforcing fiber yarn 1, carbon fibers, glass fibers and aramid fibers, polyester fibers, polyamide fibers, polyolefins. It is possible to adopt a technical means of constituting one or plural kinds selected from fiber, vinylon fiber, boron fiber, and ceramic fiber.

Further, in the present invention, a plurality of reinforcing fiber yarns 1... Are arranged in parallel, and the low-melting point thermoplastic polymer P is brought into contact with the reinforcing fiber yarns 1. The reinforcing fiber sheet substrate S in the form of a sheet is formed, and the reinforcing fiber yarns 1.1 of the reinforcing fiber sheet substrate S or the reinforcing fiber yarns and the auxiliary yarns are made of the low melting point thermoplastic polymer P. Glued,
The reinforcing fiber sheet base material S is irradiated with ionizing radiation so that the melting temperature of the low-melting-point thermoplastic polymer (P) is higher than the melting point by 40 ° C. or more, thereby reinforcing the reinforcing fiber. The substrate was completed.

In the present invention, a plurality of reinforcing fiber yarns are arranged in parallel, and a low-melting point thermoplastic polymer is brought into contact with each other while maintaining the orientation of these reinforcing fiber yarns to form a sheet. While forming the material,
After the reinforcing fiber sheet substrate is heated to a temperature equal to or higher than the melting point of the low-melting thermoplastic polymer and melted, and the reinforcing fiber yarns are bonded to each other with the low-melting thermoplastic polymer to stabilize the sheet form. ,
Irradiating the reinforcing fiber sheet substrate with ionizing radiation to increase the melting temperature of the low-melting-point thermoplastic polymer (P), thereby preventing misalignment and fraying of the reinforcing fiber substrate and having shape stability. It is possible to produce a reinforced fiber substrate excellent in mechanical properties and heat resistance of FRP.

  Therefore, according to the method for producing a reinforcing fiber base material of the present invention, the reinforcing fiber yarns are held in a predetermined orientation, and the reinforcing fibers are reinforced with thermoplastic polymers having a low melting point (or the reinforcing fiber yarns and auxiliary insertion yarns or auxiliary yarns). After melting the material, the melting temperature of the low-melting point thermoplastic polymer is increased by irradiation with ionizing radiation (complete melting is delayed). An excellent substrate and a preform using the substrate can be molded.

  In addition, the low-melting point thermoplastic polymer is cross-linked by irradiation with ionizing radiation, and the water absorption of the polymer is reduced, so that the microcrack phenomenon caused by repeated ice melting in the composite material can be prevented, and a reliable base material for composite material can be obtained. Become.

  Furthermore, since the solvent resistance is improved by cross-linking of the polymer, in the wet prepreg processing of the flat yarn fabric, the adhesive polymer for maintaining the yarn width becomes difficult to dissolve in the diluted solvent, and the weaving yarn converges with the surface tension. Therefore, it can be said that the industrial utility value is very large because it becomes a high-quality wet prepreg base material with no mesh space.

It is a front view showing the reinforced fiber base material in the manufacturing method of embodiment of this invention. It is a perspective view showing the auxiliary insertion thread used for the manufacturing method of the embodiment of the present invention. It is a front view showing the reinforced fiber base material in the manufacturing method of embodiment of this invention. It is a front view showing the modification of the reinforcing fiber base material in the manufacturing method of embodiment of this invention. It is a front view showing the modification (bidirectional reinforced textile base material) of the reinforcing fiber base material in the manufacturing method of embodiment of this invention. It is a front view showing the modification (adhesive sheet base material) of the reinforcing fiber base material in the manufacturing method of embodiment of this invention. It is a front view showing the modification (multiaxial base material) of the reinforced fiber base material in the manufacturing method of embodiment of this invention. It is a graph which shows the measurement result of the storage elastic modulus performed about the Example and comparative example of this invention. It is a graph which shows the measurement result of the storage elastic modulus performed about the Example of this invention.

  The mode for carrying out the present invention will be described in more detail with reference to the drawings specifically illustrated as follows.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the reference numeral 1 indicates a reinforcing fiber yarn (multifilament), the reference numeral 2 indicates an auxiliary insertion yarn, and the reference numeral 3 indicates a chain knitted fabric. It is a thread.

  Therefore, the manufacturing method of this embodiment will be described below. First, a plurality of reinforcing fiber yarns 1, 1... Are arranged in parallel, and the low melting thermoplastic polymer P is brought into contact with each other while maintaining the orientation of the reinforcing fiber yarns 1, 1. A reinforcing fiber sheet substrate S is formed.

  As a means for forming the sheet base material S of the present embodiment, a means for holding the arrangement of the reinforcing fiber yarns 1 by a known warp knitting technique, woven technique, or adhesive sheet technique is adopted.

  The low-melting point thermoplastic polymer P may be in the form of granules, yarns, or fabrics, or the low-melting point thermoplastic polymer P may be coated or covered on the auxiliary insertion yarn 2 or the like, and the reinforcing fiber yarns. It arrange | positions in the state contact | abutted to 1 surface.

  The reinforcing fiber yarn 1 is a multifilament in which reinforcing fibers are arranged in parallel and are bundled in a required width, and usable materials include carbon fiber, glass fiber and aramid fiber, polyester fiber, polyamide fiber, and polyolefin. It can be composed of one kind or plural kinds selected from fiber, vinylon fiber, boron fiber, and ceramic fiber.

  In particular, carbon fiber has good adhesion to the matrix resin (matrix-resin) when making it into a preform, and has excellent mechanical properties such as tensile strength and tensile modulus. Is also preferable.

  Further, as the chain knitted fabric yarn 3 (arranged in the warp direction) constituting the warp knitted fabric, a high melting point or high tension fiber such as polyester fiber, polyamide fiber, polyolefin fiber, vinylon fiber, glass fiber, aramid fiber or polysulfone fiber is used. If necessary, a material having a function such as conductivity, moisture absorption / release properties, and antibacterial properties, or a metal wire can be used. Moreover, the thread | yarn which consists of a thermoplastic resin material (for example, polyhydroxy ether etc.) fuse | melted with an epoxy resin is also employable.

  Further, as shown in FIG. 2, the auxiliary insertion yarn 2 (arranged in the weft direction) constituting the warp knitted fabric is a yarn selected from the materials listed as the material of the chain knitted fabric yarn 3 as a core yarn 22. The covering yarn can be made by winding a low melting thermoplastic polymer yarn 21 around the core yarn 22.

  The auxiliary insertion yarn 2 does not need to be a covering yarn as described above, and may be an alignment yarn made of the material of the chain knitted fabric yarn 3 and a low melting point thermoplastic polymer yarn. . In the present embodiment, the yarn-like low-melting point thermoplastic polymer P is used and knitted with the same structure as that of the auxiliary insertion thread 2. However, the present invention is not limited to this. May be inserted in parallel with the fiber bundle of the reinforcing fiber yarn 1.

  Next, the sheet substrate S configured as described above is heat-treated at a temperature equal to or higher than the melting point of the low-melting point thermoplastic polymer P, and the reinforcing fiber yarns 1 and 1 (and the reinforcing fiber yarns 1 and the auxiliary insertion yarns 2). ) With a low melting thermoplastic polymer P.

  The low-melting point thermoplastic polymer P used in the present embodiment is a polyester, polyamide, polyacrylonitrile, or polyolefin type, and among them, a copolymer nylon that provides a strong adhesive force even in a small amount is preferable. A low melting point copolymer nylon that does not require a high-temperature heating device when worn is preferred.

  In the present embodiment, since the low-melting point thermoplastic polymer P is used as the adhesive, the polymer can be brought into a molten state at a relatively low temperature, so that there is an energy saving effect and an effect that does not adversely affect the reinforcing fiber.

  In addition, the sheet base material can have form stability as an adhesive effect, and even if the sheet base material is processed randomly, the regularly arranged reinforcing fiber yarns are not disturbed. The strength characteristics of the reinforcing fiber can be fully demonstrated when molding into the material, and the reinforcing fiber is not unraveled even if the sheet base material is cut in a complicated manner, which has the advantage of high working efficiency. is there.

  Then, by performing a heat treatment at a temperature equal to or higher than the melting point of the low-melting point thermoplastic polymer P (yarn making), the low-melting point thermoplastic polymer P (yarn making) as shown in FIG. Alternatively, the intersection of the reinforcing fiber yarns 1 and the auxiliary insertion yarns 2 can be bonded as a discontinuous linear lump so that the arrangement of the reinforcing fiber yarns 1 can be firmly held.

  The form of the low-melting point thermoplastic polymer P is not limited to the fiber form, and the low-melting point thermoplastic polymer P in the form of particles, fabrics, or films is disposed on the substrate surface and heat-treated. Is also included.

  Moreover, in this embodiment, it is preferable that it is 80-180 degrees as melting | fusing point of the low melting point thermoplastic polymer P, and it is 80-150 degreeC as a more preferable range. The lower melting point of the polymer P is as low as possible in the bonding process, which leads to lower temperature heating or increased processing speed, and can be expected to reduce processing costs. Heating is also performed in preform processing in which a plurality of sheet base materials are laminated and bonded by heating. Time is shortened and productivity is improved.

  However, when the melting point is 80 ° C. or lower, the glass transition point is relatively low, and the polymer is flexible even if the polymer does not melt due to high atmospheric temperature (for example, at high temperatures in summer), and the reinforcing strength is reduced by reducing the adhesive strength. The melting point of the low-melting point thermoplastic polymer P is preferably 80 ° C. or higher, since the arrangement of the low-melting point thermoplastic polymer P is liable to be disturbed and may be eluted at the curing temperature at the time of molding or may inhibit the curing.

  On the other hand, in terms of the adhesive effect in the reinforcing fiber sheet substrate S and the physical properties when molded into a composite material, the higher the melting point, the better. However, the sizing agent or the coupling agent used for the reinforcing fiber or the like is used in the heating time. However, the phenomenon of scorching is seen at about 200 ° C, and heating at higher temperatures may impair the functions of the sizing agent and coupling agent, so the maximum temperature of the melting point is 180 ° C. More preferably, it is 150 degrees C or less.

  When viewed as a composite material, the low-melting point thermoplastic polymer P contained in the reinforcing fiber sheet substrate S becomes a foreign matter, but the amount used is the function of maintaining the arrangement of reinforcing fiber yarns, or the substrate during preform processing. What is necessary is just to perform the mutual adhesion | attachment function, and as a range of preferable content, it is 0.5 to 10% with respect to a base-material weight. If the content is 0.5% or less, the intended adhesion function is insufficient. On the other hand, if the content is 10% or more, the adhesive force increases, but the physical properties are reduced when molded into a composite material. From that.

  Next, the reinforcing fiber sheet substrate S (warp knitted fabric) obtained in the bonding step is irradiated with ionizing radiation to crosslink the low melting point thermoplastic polymer P to increase the melting temperature. By irradiating with ionizing radiation in this manner, the degree of crosslinking of the thermoplastic (copolymerized) polymer is increased to a predetermined range, thereby obtaining a modified thermoplastic copolymer having an increased melting temperature.

  At this time, even if the degree of crosslinking is increased, if it is lower than the predetermined value, it is difficult to obtain the effect of increasing the melting temperature, and the improvement in temperature at which the thermoplastic copolymer is eluted from the FRP cross section is small. The polymer will elute and the location where the thermoplastic copolymer was present will become voids, and the mechanical properties will deteriorate, and if the resin is cured at high temperature during molding, the resin will cure In addition, the low-melting point thermoplastic polymer P is melted and the shape stability of the base material is lost, so that the orientation of the reinforcing fibers is disturbed and the mechanical properties are lowered.

  On the other hand, if the degree of cross-linking is higher than a predetermined value, the thermoplastic itself deteriorates and the adhesive strength and the like are lowered, which is not preferable. Further, when the degree of crosslinking is increased to a particularly preferable range, it can be re-fused relatively easily. Therefore, after the reinforcing fiber sheet substrate S is laminated, the layers can be bonded by heating. Therefore, an integrated preform can be produced.

  Here, due to the increase in the degree of crosslinking, the storage elastic modulus E ′ measured in the DMA measurement used when measuring the viscoelastic properties is changed, and the storage elastic modulus E ′ becomes 100 Pa or less in the temperature range above the melting point. The temperature rises. Therefore, as described above, the elution temperature of the low-melting polymer is increased, and the elution of the low-melting polymer from the FRP cross section can be prevented. Therefore, voids are not generated inside the FRP, and deterioration of mechanical properties can be prevented.

  Further, the low melting point polymer preferably has a melting point of 80 to 150 ° C., but a general matrix resin of FRP has a Tg (glass transition point) of about 120 ° C., and Tg when heat resistance is required depending on the application. Use a higher resin. Therefore, when a low melting point polymer having a melting point of 80 ° C. is used, it is preferable that the storage elastic modulus E ′ is 100 Pa or more at a temperature of melting point + 40 ° C. or higher because there is a difference between Tg of the matrix resin and 40 ° C. .

  Further, when a preform is produced, a thermoplastic copolymer polymer mesh-like woven fabric, nonwoven fabric, film, particle or the like may be adhered between the layers. It is preferable that the thermoplastic copolymer for adhering these layers also increases the melting temperature by increasing the degree of crosslinking to a predetermined range for the above reasons. Here, it is not necessary to be the same type of polymer as the thermoplastic copolymer that retains the form of the above-mentioned sheet, and further, the degree of cross-linking does not need to be within a predetermined range, and the thermoplastic copolymer used for the substrate is not necessary. You may use the polymer more than the melting temperature of a polymerization polymer. Furthermore, in addition to the problems regarding the melting temperature, problems regarding resistance to organic solvents can be improved.

  In other words, when producing a so-called “wet prepreg” that can be obtained through a drying process after being immersed in a resin layer using a reinforcing fiber substrate in which low-melting nylon is used, The organic solvent is diluted with an organic solvent in order to lower the temperature and improve the impregnation property, but there is a problem that the low melting point nylon is melted by the organic solvent.

  In other words, even if the degree of cross-linking increases, if it is smaller than the predetermined value, the low melting point nylon is almost melted, the sealing effect is lost, and the reinforcing fiber bundle converges into a mesh shape due to the surface tension of the low viscosity resin. Further, there is a problem that the reinforcing fiber orientation direction of the reinforcing fiber base is shifted or wrinkled due to the tension applied to the reinforcing fiber base or friction with the guide roller in the middle of the manufacturing process. Therefore, from the viewpoint of solvent resistance, it is preferable that the degree of crosslinking is not less than a predetermined range, and the higher the degree of crosslinking, the more difficult it is to dissolve in an organic solvent.

  From the above, it is necessary to design the degree of cross-linking to be higher than a predetermined value and within a predetermined range according to the use of the reinforcing fiber base material. The cross-linking degree of the low melting point thermoplastic polymer P is the melting point + 40 ° C. Even when heated to the above temperature, it is preferable to set so that a storage elastic modulus E ′ of 100 Pa or more can be maintained. The degree of crosslinking can be adjusted by electron beam irradiation treatment.

  Moreover, when performing an electron beam irradiation process, it is preferable to make the absorbed dose of the electron beam into a predetermined range. If the absorbed dose is too small, the effect of causing crosslinking in the low-melting point thermoplastic polymer P becomes small, and a desired preferable degree of crosslinking cannot be obtained. That is, it is difficult to obtain the effect of improving the temperature at which the thermoplastic copolymer is eluted from the FRP cross section. On the other hand, if the absorbed dose is too large, the thermoplastic copolymer polymer will turn yellow or shrink, which is not preferable.

In addition, it is preferable to irradiate so that the acceleration voltage E may satisfy | fill following Formula (Formula 1) on the irradiation conditions of an electron beam.

  Here, in the electron beam irradiation, the absorbed dose distribution in the thickness direction of the reinforced fiber base material or preform that is the object to be irradiated becomes smaller with respect to the set irradiation amount. It is preferable to adjust the absorbed dose. That is, the acceleration voltage E depends on the absorbed dose in the thickness direction of the object to be irradiated, and if the acceleration voltage is smaller than the right side of (Equation 1), the amount of electron beam absorption on the opposite surface side compared to the electron beam irradiation side surface. There are few variations in the melting temperature rise of the low-melting point thermoplastic polymer P, and the melting temperature of the thermoplastic copolymer varies in the thickness direction. On the other hand, if the thickness of the irradiated object is too thick, the absorbed dose is too small on the side opposite to the electron beam irradiation side and the effect of increasing the melting temperature cannot be obtained. Therefore, the acceleration voltage E is preferably larger than the right side of (Equation 1).

  As an electron beam irradiation method, irradiation may be performed from one side of the irradiated object with an acceleration voltage E ′ satisfying (Equation 1) with respect to the thickness t ′ of the irradiated object. Double-sided irradiation may be performed by irradiating an electron beam from both sides of the object to be irradiated with an acceleration voltage E ′. In the case of double-sided irradiation, an accelerating voltage that is ½ of the accelerating voltage E that satisfies (Equation 1) may be sufficient for the irradiated object, so that the electron beam irradiation can be effectively performed especially on a thick irradiated object Yes. The irradiation method and irradiation conditions can be appropriately selected according to the thickness of the object to be irradiated and the specifications of the electron beam irradiation apparatus.

Furthermore, in the electron beam irradiation process, the electron beam irradiation dose D per irradiation satisfies the following formula in each material used for the reinforcing fiber base material, and is repeatedly irradiated so as to satisfy this condition. It is preferable that the absorbed dose of the electron beam with the sum of D described above be in a predetermined range of 200 to 1000 kGy. When the irradiation dose is 200 kGy or less, it is difficult to obtain the effect of increasing the melting temperature of the low melting point polymer. In addition, in the case of 1000 kGy or more, it is necessary to repeat the electron beam irradiation process many times, so that productivity is poor, or depending on the type of the low melting point polymer, it is difficult to obtain further effects due to sufficient crosslinking, There is also a problem that it itself deteriorates. More preferably, it is 250-600 kGy.

  In addition, since the irradiated object is heated by the energy of the electron beam, the temperature rise due to the energy given by the electron beam is the difference between the melting point of the material and the room temperature in consideration of the melting point and specific heat of each material used for the substrate. Must be smaller.

  In other words, if the right side is larger than the left side (difference between the melting point of the material and room temperature), the material of the large right side exceeds the melting point, so the form of the sheet base material cannot be maintained, and the form stability is lost. The orientation direction of the reinforcing fiber yarn is disturbed, and the mechanical properties of the base material are deteriorated. Therefore, all the materials used for the reinforcing fiber substrate are repeatedly irradiated with the electron beam irradiation dose D satisfying (Equation 2), and the sum of the electron beam irradiation doses D becomes the above-mentioned absorbed dose of electron beams. It is preferable.

  Furthermore, it is preferable to adjust the equilibrium moisture content (JIS L1013) of the thermoplastic copolymer obtained by electron beam irradiation within a predetermined range. If this equilibrium moisture content is large, it is easy to absorb moisture. For example, when FRP is molded from a reinforced fiber base material using a copolymer nylon with relatively high water absorption, the resin is not sufficiently cured by moisture, Evaporates into voids, the mechanical properties of the resulting FRP deteriorate and do not become high-quality FRP. In addition, moisture remains in the FRP and is repeatedly exposed to a low temperature, a normal temperature, or a high temperature environment. When ice melting is repeated, microcracks are generated, and a reliable material cannot be obtained. Therefore, the equilibrium moisture content is preferably as small as possible.

  In the present embodiment, a warp knitted reinforcing fiber base in which reinforcing fibers are arranged in one direction in the sheet base forming process is mentioned, but the form of the base is not necessarily limited to the above-described reinforcing warp knitted base. However, as shown in FIG. 4, a unidirectional woven fabric in which warp yarns in which reinforcing fiber yarns 1 are arranged in one direction and weft yarns of auxiliary insertion yarns 2 are crossed and the intersections are bonded with a low-melting point thermoplastic polymer P. It may be configured.

  Further, as shown in FIG. 5, a warp reinforcing fiber yarn 1 and a weft reinforcing fiber yarn 1 are interlaced with each other, and a bi-directional woven fabric in which the intersection is bonded with a low-melting point thermoplastic polymer P is configured. Furthermore, as shown in FIG. 6, an adhesive sheet was formed by adhering the reinforcing fiber yarns 1 arranged in one direction to the net material 4 to which the low melting point thermoplastic polymer P was adhered. Things can be used.

  Furthermore, a sheet base material S · S in which the reinforcing fiber yarns 1 are arranged in parallel and a non-woven fabric made of a low-melting point thermoplastic polymer P are laminated on the uppermost layer and integrated with the stitch yarn 5, and the non-woven fabric is melted after heat treatment. A configuration such as an adhesive multiaxial base material in which polymer lumps are scattered on the surface is also included.

  Furthermore, a reinforced fiber knitted fabric knitted using a reinforcing fiber yarn as a material for a chain knitted fabric yarn or an insertion yarn may be used.

  Reinforced fiber base materials manufactured by the manufacturing process as described above are conventionally dissolved in a high temperature atmosphere due to the low melting temperature of the low melting point thermoplastic polymer contained in the base material, and the base material is disturbed during high temperature molding. The deterioration of the physical properties of the molded product due to this is greatly improved.

  Using the following materials, 123 reinforcing fiber bundles and chain knitted fabric yarn are arranged so that the wale interval is 4.2 mm pitch, and the insertion yarn is swung to 6 mm pitch, and the insertion yarn on one side of the reinforcing fiber base material A knitted reinforcing fiber base material is knitted using a yarn covered with a thermoplastic copolymer polymer yarn for (back side insertion yarn), and the thermoplastic copolymer polymer yarn is melted by heat treatment to form a chain knitted fabric yarn and an insertion yarn. The reinforcing fiber substrate of the present invention in which the absorbed dose of the thermoplastic copolymer was set to 200 kGy by electron beam irradiation (hereinafter referred to as “Example 1”) Was made.

  In this embodiment, the reinforcing fiber sheet substrate S is irradiated with a unit dose of ionizing radiation a plurality of times. Specifically, when electron beam irradiation was performed, the irradiation amount was set to 100 kGy, and irradiation was performed twice to obtain a reinforced fiber base material having an absorbed dose of 200 kGy.

<Material conditions of Example 1>
1) Reinforced fiber bundle: 800 tex carbon fiber bundle made up of 12,000 multifilaments, 2) Chain knitted fabric yarn: Polyester fiber yarn made up of 33 decitex multifilament, 3) Front insertion yarn; From 33 decitex multifilament Polyester fiber yarn, 4) Back insertion yarn; Covering yarn comprising polyester fiber yarn made of 33 dtex multifilament and copolymer nylon resin having a melting point of 110 ° C., covering a multifilament yarn having a fineness of 56 dtex

  Similarly, the reinforcing fiber base materials of the present invention of “Example 2” and “Example 3” were prepared with electron beam irradiation doses of 300 kGy and 400 kGy. Similarly, the electron beam irradiation condition was set to 100 kGy, and irradiation was performed 3 times and 4 times, respectively.

  Moreover, as a comparative example, the electron beam irradiation amount of 0 kGy, that is, no electron beam irradiation and 100 kGy irradiation were manufactured as “Comparative Example 1” and “Comparative Example 2”, respectively, in the same manner as the above manufacturing method.

  And after cutting out each of these reinforcing fiber bases to 250 × 250 mm, laminating 6 sheets so that the reinforcing fibers are in the same direction in the mold, covering the top with a film, and impregnating the epoxy resin under vacuum, The resin was heated and cured to produce an FRP plate. This FRP plate was cut into 50 × 50 mm, put in an oven, and observed whether the copolymer nylon was eluted from the FRP cross section. The temperature in the oven is raised by 5 ° C. from 110 ° C., which is the melting point of the nylon yarn, FRP is put in each temperature atmosphere for 30 minutes, and the elution temperature is measured.

From the above, it was found that the elution temperature increased as the absorbed dose increased.
This is because the rack strength of the nylon yarn is increased by the electron beam irradiation, and the melting temperature is increased.

<Storage elastic modulus measurement by DMA>
Next, the nylon fiber used in this example was put into a mold, melted and cooled to produce a flat plate having a thickness of 0.5 mm. Next, the sample was irradiated with an electron beam in the same manner as the reinforcing fiber sheet base material, and samples with electron beam doses of 200 kGy, 300 kGy, 400 kGy, and 600 kGy were prepared. N4 ”was similarly irradiated with an electron beam dose of 0 kGy (no electron beam irradiation) and 100 kGy, and“ Comparative Example N1 ”and“ Comparative Example N2 ”were cut into sizes that fit in the jig of the DMA measuring machine.

  Then, the storage elastic modulus E 'was measured when the temperature was increased by 2 [deg.] C./min while applying a vibration at a frequency of 1 Hz with a DMA measuring device. The results are shown in FIG. 8 for “Comparative Example N1”, “Comparative Example N2”, and “Example N1”, and FIG. 9 for “Example N2”, “Example N3”, and “Example N4”. The measurement temperature range was −50 ° C. to 150 ° C.

  In the measurement results shown in FIGS. 8 and 9, in Comparative Examples N1 and N2, E ′ is 100 Pa or less in the temperature range lower than the melting point + 40 ° C., whereas the change in behavior is large at 200 kGy of Example N1, but E 'Is 100 Pa or more. Moreover, when Examples N2, N3, and N4 and the amount of electron beam irradiation increase, the storage elastic modulus above melting | fusing point becomes high. Therefore, it can be inferred that increasing the electron beam dose increases the melting temperature and leads to the results of [Table 1].

1 Reinforcing fiber yarn 2 Auxiliary insertion yarn
21 Covering thread
22 Core yarn 3 Chain knitted fabric yarn 4 Net material 5 Stitch yarn S Reinforced fiber sheet substrate LS Laminated substrate P Low melting point thermoplastic polymer

Claims (10)

A plurality of reinforcing fiber yarns (1...) Are arranged in parallel, and the low-melting point thermoplastic polymer (P) is brought into contact with each other while maintaining the orientation of these reinforcing fiber yarns (1. While forming a reinforcing fiber sheet substrate (S) in the form of a sheet,
This reinforcing fiber sheet substrate (S) is heated and melted to a temperature equal to or higher than the melting point of the low-melting point thermoplastic polymer (P), and the reinforcing fiber yarns (1.1) or the reinforcing fiber yarns and auxiliary yarns After adhering with the low melting point thermoplastic polymer (P) and stabilizing the sheet form,
Irradiating ionizing radiation to the reinforcing fiber sheet substrate (S) to increase the melting temperature of the low-melting-point thermoplastic polymer (P).   The method for producing a reinforcing fiber substrate according to claim 1, wherein the reinforcing fiber sheet substrate (S) is irradiated with ionizing radiation of a unit dose multiple times. The low-melting-point thermoplastic polymer (P) is obtained by maintaining the orientation of the reinforcing fiber yarns (1...) With the auxiliary insertion yarns (2). While forming the reinforcing fiber sheet base material (S) in contact with the sheet,
The method for producing a reinforcing fiber substrate according to claim 1 or 2, wherein the reinforcing fiber yarn (1) and the auxiliary insertion yarn (2) are bonded by a low-melting point thermoplastic polymer (P). The method for producing a reinforcing fiber substrate according to any one of claims 1 to 3, wherein the ionizing radiation is an electron beam, and the electron beam is irradiated with an acceleration voltage E satisfying the following formula.
  The auxiliary insertion yarn (2) to which the yarn composed of the low melting point thermoplastic polymer (P) or the low melting point thermoplastic polymer yarn is attached is brought into contact with the reinforcing fiber yarn (1) arranged at least in the warp direction, thereby knitting The method for producing a reinforcing fiber substrate according to any one of claims 1 to 4, wherein the tissue or woven fabric structure is formed.   On the sheet-like net material (4) to which the low-melting point thermoplastic polymer (P) is adhered, the reinforcing fiber yarns (1) are arranged in parallel in the warp direction and heated, and then the net material ( It adheres to 4), The manufacturing method of the reinforced fiber base material as described in any one of Claims 1-5 characterized by the above-mentioned. A plurality of reinforcing fiber sheet substrates (S) in which the reinforcing fiber yarns (1.1,...) Are arranged in parallel, and the reinforcing fiber yarn substrates (1) of these reinforcing fiber sheet substrates (S) are at different angles. While forming a laminated base material (LS) by laminating and integrating by multi-axis stitching means,
The reinforcing fiber group according to any one of claims 1 to 6, wherein the low-melting point thermoplastic polymer (P) is arranged on at least one side of the outermost layer of the sheet in the form of a yarn, a fabric or a powder. A method of manufacturing the material.   The low-melting point thermoplastic polymer (P) is made into a copolymer having a melting point of 80 to 180 ° C, and is contained in an amount of 0.5 to 10% based on the weight of the base material. The manufacturing method of the reinforced fiber base material of description.   Reinforcing fiber of reinforcing fiber yarn (1) is composed of one or more kinds selected from carbon fiber, glass fiber and aramid fiber, polyester fiber, polyamide fiber, polyolefin fiber, vinylon fiber, boron fiber, ceramic fiber The manufacturing method of the reinforced fiber base material as described in any one of Claims 1-8 characterized by the above-mentioned. A plurality of reinforcing fiber yarns (1... 1) are arranged in parallel, and the low-melting point thermoplastic polymer (P) is brought into contact with the reinforcing fiber yarns (1. While the reinforcing fiber sheet base material (S) made into a sheet is formed,
The reinforcing fiber sheet base (S) is bonded to the reinforcing fiber yarns (1.1) with the low-melting point thermoplastic polymer (P),
Reinforcement characterized in that the melting temperature of the low-melting point thermoplastic polymer (P) is higher than the melting point by 40 ° C. or more on the reinforcing fiber sheet material in which the reinforcing fiber sheet substrate (S) is irradiated with ionizing radiation. Fiber substrate.