JP6303849B2 - FIBER-REINFORCED RESIN SHEET, INTEGRATED MOLDED ARTICLE AND METHOD FOR PRODUCING THEM - Google Patents

Description

  The present invention relates to a fiber-reinforced resin sheet, an integrally molded article, and a method for producing them, and more particularly to a joining technique using different members, a fiber-reinforced composite material and a metal material.

  Fiber reinforced plastic (FRP) composed of reinforced fibers and matrix resin is widely used in various industrial applications because of its excellent light weight and mechanical properties. Among them, FRP using a thermoplastic resin has attracted particular attention in recent years because it can be mass-produced by high-speed molding in addition to the light weight and mechanical characteristics described above and is excellent in recyclability.

  In general, in the manufacture of parts and structures using FRP, since a plurality of members are integrated, a step of joining members or materials is required. As this joining method, mechanical joining methods such as bolts, rivets, and screws, and joining methods using an adhesive are generally known. The mechanical joining method is a highly versatile technique, but there are cases where the processing cost of the joining portion, the weight increase due to bolts, etc., and the weakening due to the stress concentration in the working portion may be problems. In addition, in a bonding method using an adhesive, there may be a problem that the limit of the bonding strength of the adhesive depends on the shear strength of the adhesive.

  On the other hand, regarding the bonding and bonding means between the fiber reinforced composite material and the metal material, technological development is actively carried out mainly from the viewpoint of the affinity between the metal member and the adhesive. Patent Document 1 discloses a technique for improving affinity with a metal layer and improving adhesive strength. However, in the present technology, a new adhesive must be selected for each type of metal material, and cannot be used for a wide variety of metal materials. Moreover, in patent document 2, the technique which impregnates the thermosetting resin in the nonwoven fabric which consists of glass fibers, and laminate | stacks it on metal foil is provided. According to this method, high bending strength is expressed by the glass fiber base material impregnated with the metal foil and the thermosetting resin, and the use of kraft paper for the intermediate layer is excellent in economic efficiency. However, regarding the adhesiveness between the metal foil and the glass fiber base material, in addition to not being mentioned, since the glass fiber is used as the base material, the layer impregnated with the thermosetting resin has low shear strength. Conceivable. Patent Document 3 discloses a technique for improving the adhesiveness by processing the surface of a resin molded body to form fibrils and impregnating with other components such as an adhesive. However, in the present technology, since the resin molded body and the fibrils composed thereof are the same type, it is insufficient for improving the adhesive strength.

JP-A-7-214725 JP-A-61-255850 International Publication No. 2003/013844

  Accordingly, the present invention is to solve the above-described technical problems and to provide an integrated molded product having strong bonding strength even in the bonding of different members such as a fiber reinforced composite material and a metal material. It is providing the fiber reinforced resin sheet which can manufacture a molded article.

In order to solve the above problems, the fiber reinforced resin sheet of the present invention employs the following configuration.
A fiber reinforced resin sheet that is impregnated with a thermoplastic resin on one side in the thickness direction of a nonwoven fabric composed of reinforcing fibers and impregnated with an adhesive on the other side in the thickness direction of the nonwoven fabric. The reinforcing fiber single fiber constituting the nonwoven fabric penetrates both the layer impregnated with the thermoplastic resin and the layer impregnated with the adhesive, and in the sheet, the thermoplastic resin and the adhesive There maximum height Ry50μm above, ing to form an interface layer having an average roughness Rz30μm more irregularities, fiber-reinforced resin sheet.

Moreover, in order to solve the said subject, the manufacturing method of the fiber reinforced resin sheet of this invention employ | adopts the following structure.
A method for producing the above-described fiber-reinforced resin sheet, which includes the following steps (I) and (II).
(I) While impregnating the thermoplastic resin on one side in the thickness direction of the nonwoven fabric composed of reinforcing fibers, and on the other side in the thickness direction of the nonwoven fabric, a region where the reinforcing fibers constituting the nonwoven fabric are exposed, Step of forming the reinforcing fiber so that the volume ratio Vfm of the reinforcing fiber in the region is 20% by volume or less (II) Step of impregnating the region in which the reinforcing fiber constituting the nonwoven fabric is exposed with an adhesive

Moreover, in order to solve the said subject, the integrated structure of this invention employ | adopts the following structure.
An integrated molded product obtained by bonding the first member including the fiber reinforced resin sheet and the second member made of metal with an adhesive in the fiber reinforced resin sheet.

Furthermore, in order to solve the said subject, the manufacturing method of the integrally molded product of this invention employ | adopts the following structure.
A method for manufacturing an integrated molded product as described above, wherein the first member is bonded to the second member by pressure heating.

  According to the present invention, even if adherends made of different members, ie, a fiber reinforced composite material and a metal material, are joined to each other due to the effect of improving the shear strength of the bonded region derived from the anchoring effect of the reinforcing fiber. An integrated molded product having bonding strength can be provided. Furthermore, since the fiber-reinforced resin sheet of the present invention includes an adhesive surface that can be bonded to various metal members, the integrated molded product obtained therefrom is excellent in the development of various products. It can be suitably applied as a mounting member in applications such as members, electrical / electronic equipment casings, aircraft members, and the like.

The schematic diagram which shows an example of the fiber reinforced resin sheet of this invention. The schematic diagram which shows an example of the interface layer of the fiber reinforced resin sheet of this invention. The schematic diagram which shows an example of the dispersion state of the reinforced fiber in the nonwoven fabric which consists of a reinforced fiber used by this invention. The schematic diagram which shows an example of the cross section of the fiber reinforced resin sheet of this invention. The graph which shows an example of the mass fraction of the fiber bundle in the nonwoven fabric which consists of a reinforced fiber used by this invention. The perspective view which shows the tensile shearing adhesion test piece used in the Example and comparative example of this invention.

  The fiber-reinforced resin sheet of the present invention includes a nonwoven fabric composed of reinforcing fibers (hereinafter, a nonwoven fabric composed of reinforcing fibers is also referred to as a reinforcing fiber nonwoven fabric) as a constituent element. Here, the nonwoven fabric is a planar body composed of reinforcing fibers, and the reinforcing fiber nonwoven fabric is a kind of reinforcing fiber mat. The reinforcing fiber nonwoven fabric may contain a resin component in the form of powder or fiber in addition to the reinforcing fiber.

The fiber-reinforced resin sheet of the present invention is impregnated with a thermoplastic resin on one side in the thickness direction of the reinforcing fiber nonwoven fabric and with an adhesive on the other side in the thickness direction of the nonwoven fabric. That is, it has a layer impregnated with a thermoplastic resin (hereinafter also referred to as a thermoplastic resin layer) on one side in the thickness direction of the reinforcing fiber nonwoven fabric, and an adhesive on the other side in the thickness direction of the nonwoven fabric. A layer impregnated with (hereinafter also referred to as an adhesive layer) is formed. The fiber-reinforced resin sheet of the present invention, monofilaments of the reinforcing fibers constituting the nonwoven fabric, have a penetration structure both of the thermoplastic resin layer and the adhesive layer, during the sheet, a thermoplastic resin adhesive The agent has an uneven shape having a maximum height Ry of 50 μm or more and an average roughness Rz of 30 μm or more to form an interface layer .

  Here, the one aspect | mode of the fiber reinforced resin sheet in this invention is shown in FIG. FIG. 1 shows a state in which a reinforced fiber nonwoven fabric (reinforced fiber 2 in FIG. 1) is impregnated with a thermoplastic resin and an adhesive (thermoplastic resin 3 and adhesive 4 in FIG. 1). That is, it refers to an aspect in which the reinforcing fibers constituting the nonwoven fabric are substantially in the same state and the nonwoven fabric is impregnated with the thermoplastic resin and the adhesive to form the interface layer. And it has the penetration structure in which the single fiber of the reinforced fiber penetrated both the thermoplastic resin layer and the adhesive bond layer. In the reinforced fiber resin sheet, the presence of single fibers penetrating both the thermoplastic resin layer and the adhesive layer makes it excellent in bonding of the thermoplastic resin and the adhesive. Further, when such a fiber reinforced resin sheet is joined with a different member (adhered body) and an adhesive in the fiber reinforced resin sheet, the shear strength derived from the penetration of the reinforced fiber is also improved in the adhesive layer. The effect is obtained and the bonding strength is improved, and the necessity of considering the affinity between the adhesive and the adherend which should be taken into consideration is low. If such an intrusion structure does not exist, the adherend and the fiber reinforced resin sheet will be bonded only with the original shear strength of the adhesive, and the joint strength depends on the shear strength of the adhesive, so it is integrated molding In the case of a product, a satisfactory bonding strength is not always obtained.

  Such penetration structure can be easily determined by observing a cross section in the thickness direction of the fiber reinforced resin sheet using an optical microscope or an electron microscope.

In the fiber reinforced resin sheet of the present invention, the thermoplastic resin and the adhesive have a concavo-convex shape having a maximum height Ry of 50 μm or more and an average roughness Rz of 30 μm or more to form an interface layer. It is preferable because the bonding of the layers becomes strong. Here, the interface layer formed by the thermoplastic resin and the adhesive in the fiber-reinforced resin sheet of the present invention will be described in detail with reference to FIG. FIG. 2 is an enlarged view of the interface layer between the thermoplastic resin and the adhesive based on the vertical cross section with respect to the surface direction X of the fiber reinforced resin sheet 5. In FIG. 2, a thermoplastic resin 6 and an adhesive 7 are impregnated in a reinforced fiber nonwoven fabric (not shown), and a concavo-convex shape extending in the surface direction X at the approximate center in the thickness direction Z of the fiber reinforced resin sheet. The interface layer which has is formed through the reinforced fiber nonwoven fabric. Such an interface layer has a plurality of concave portions and convex portions in the thickness direction Z, and of these, a drop in the Z direction between the concave portion 9 having the largest depression and the protruding portion 8 having the largest protrusion is defined as dmax. In addition, although the convex part 8 is seen as an independent island shape in the drawing, the deepest penetration amount including this is taken as the extreme end of each concave-convex part. On the other hand, of the concavo-convex shape in the interface layer, a drop in the Z direction between the concave portion 11 having the smallest depression and the convex portion 10 having the smallest protrusion is defined as dmin. Here, dmax is the maximum height Ry referred to in the present invention, and the average value of dmax and dmin is defined as the average roughness Rz referred to in the present invention.

  The fiber reinforced resin sheet of the present invention has a strong bond between the thermoplastic resin layer and the adhesive layer in addition to the reinforcing effect to the adhesive derived from the reinforced fiber, because the above-described interface layer is formed. A fiber reinforced resin sheet is provided. Furthermore, according to the interface layer of the said aspect, it becomes unnecessary to provide a special restriction | limiting in the combination of the thermoplastic resin and adhesive agent to apply. That is, a thermoplastic resin and an adhesive that form an anchoring structure intricately interlaced with a reinforcing fiber nonwoven fabric to mechanically bond each resin. And the adhesive can be neglected, and even if it is a combination that is inherently difficult to coexist, it can be easily and firmly joined, and thus has the special effect of the present invention. On the other hand, when the maximum height Ry in the interface layer is less than 50 μm, the anchoring structure is not sufficiently formed, so that satisfactory bonding strength cannot be expressed in the interface layer of the integrally molded product. When the average roughness Rz is less than 30 μm, the uneven shape is uneven, so that the strength expression in the interface layer becomes unstable and the reliability is lowered. The effect of the present invention can be sufficiently achieved if the maximum height Ry in the interface layer is 50 μm or more and the average roughness Rz is 30 μm or more. However, if the Ry is 300 μm and Rz is 100 μm, the effect of the present invention is ensured. Alright to do.

  A method of measuring the maximum height Ry and the average roughness Rz in the interface layer based on the cross-sectional observation of the fiber reinforced resin sheet can be exemplified. The adhesive is cured at a temperature at which the thermoplastic resin does not melt in the fiber reinforced resin sheet. Then, a sample is prepared by cutting out a small piece from the fiber reinforced resin sheet in which the adhesive is cured, embedding with an epoxy resin, and polishing so that a vertical section in the thickness direction becomes an observation surface. By observing the sample with a microscope, an image corresponding to FIG. 2 can be confirmed in the visual field. From this, the vertical drop dmax between the concave part with the largest depression and the convex part with the largest protrusion among the concave / convex interface defined above, and the vertical drop dmin between the concave part with the smallest depression and the convex part with the smallest protrusion. Measure each. This operation is performed 10 times for different images, and the largest value among the measured dmax can be set as the maximum height Ry (μm) of the uneven shape in the interface layer. Moreover, the value which remove | divided the sum total of dmax and dmin measured by N number can be made into the average roughness Rz of the uneven | corrugated shape in an interface layer.

  The reinforcing fiber nonwoven fabric in the present invention has a function as an impregnation medium for forming an interface layer in which a thermoplastic resin and an adhesive are anchored to each other. The thermoplastic resin generally has a high viscosity, and is several tens to several thousand times that of the thermosetting resin. Therefore, it is preferable that the reinforcing fiber nonwoven fabric has a structure that can be easily impregnated with a thermoplastic resin. Therefore, the volume ratio Vfm of reinforcing fibers in the nonwoven fabric is preferably 20% by volume or less. When the volume ratio Vfm of the reinforcing fiber in the nonwoven fabric is 20% by volume or less, the volume ratio of the reinforcing fiber in the adhesive layer is also 20% by volume or less.

  The volume ratio Vfm of the reinforcing fibers in the nonwoven fabric refers to the volume content of the reinforcing fibers contained per unit volume of the nonwoven fabric. By setting the volume ratio Vfm of the reinforcing fiber in the nonwoven fabric within the above range, there are many voids in the nonwoven fabric, and a flow path is formed when the adhesive is impregnated. Therefore, the adhesive is easily impregnated. Can do. As a result, excellent adhesiveness and reliability are provided when an integrally molded product is obtained. Further, since the flow path in the nonwoven fabric becomes complicated, the impregnation of the adhesive proceeds in a complicated manner, and the formation of an anchoring structure having an uneven shape in the interface layer between the thermoplastic resin and the adhesive is promoted. Therefore, the obtained fiber reinforced resin sheet has strong bonding of different resins, and can realize high bonding strength when it is formed as an integrally molded product.

  The volume ratio Vfm of the reinforcing fiber in the nonwoven fabric is preferably 15% by volume or less, more preferably 10% by volume or less. The lower limit value of the volume fraction Vfm of the reinforcing fiber in the nonwoven fabric is not particularly limited, but about 3% by volume is sufficient in view of practicality such as handleability of the nonwoven fabric and moldability when formed into a fiber reinforced resin sheet.

The volume ratio Vfm of the reinforcing fiber described above can be exemplified by a method of measuring from the mass and volume of the reinforcing fiber nonwoven fabric. The fiber reinforced resin sheet is sandwiched between metal meshes to burn away the thermoplastic resin component, or the remaining reinforced fiber nonwoven fabric, or the thermoplastic resin is immersed in a soluble solvent while being sandwiched between metal meshes. Then, the thickness is measured from the reinforcing fiber nonwoven fabric remaining after dissolving the resin component. The thickness tm of the reinforcing fiber nonwoven fabric is a value measured after applying 50 kPa for 20 seconds in accordance with “Method for measuring thickness of carbon fiber fabric” defined in JIS R7602 (1995). In the measurement, if it is difficult to maintain the shape of the reinforcing fiber nonwoven fabric, the thickness is measured through the metal mesh, and then the thickness of the metal mesh is subtracted. The mass Wm of the reinforcing fiber nonwoven fabric is a value measured in accordance with “Method for measuring weight per unit area of carbon fiber fabric” defined in JIS R7602 (1995). As the volume of the reinforcing fiber nonwoven fabric, a value calculated from the area and thickness of the reinforcing fiber nonwoven fabric subjected to mass measurement is used. From the mass Wm and thickness tm measured above, the volume fraction Vfm (volume%) of the reinforcing fiber is calculated by the following formula. Here, ρf in the formula is the density (g / cm ³ ) of the reinforcing fiber, and S is the cut-out area (cm ² ) of the reinforcing fiber nonwoven fabric.
Vfm (volume%) = (Wm / ρf) / (S × tm) × 100

  The reinforcing fiber nonwoven fabric in the present invention also has a function as a reinforcing material in the interface layer of the thermoplastic resin and the adhesive. The reinforcing fiber nonwoven fabric satisfying the volume ratio Vfm of the reinforcing fiber described above has a bulkiness caused by the steric hindrance of the reinforcing fiber, and therefore fiber orientation in the thickness direction of the reinforcing fiber nonwoven fabric is produced. Therefore, the interface layer spreading in the in-plane direction of the fiber reinforced resin sheet and the reinforcing fiber form a certain angle, and the probability that the reinforcing fiber is disposed across the interface layer is increased. As a result, fiber breakage and interface peeling can be effectively generated with respect to the applied shear load, and strong bonding in the interface layer is given. On the other hand, when the volume fraction Vfm of the reinforcing fiber is out of the above-described range, the reinforcing fiber cannot be effectively used because the reinforcing fiber is arranged substantially in parallel with the in-plane direction where the interface layer exists. The shear strength of is impaired.

  In the present invention, as described above, the reinforcing fiber needs to have many voids in the aggregate, and takes the form of a non-woven fabric in order to satisfy such an aspect. Furthermore, as a form of the reinforcing fiber constituting the nonwoven fabric, the discontinuous reinforcing fiber having a finite length cut to a predetermined length is preferably a discontinuous reinforcing fiber from the viewpoint of easily adjusting the nonwoven fabric.

  Here, the form of the nonwoven fabric refers to a form in which strands of reinforcing fibers and / or monofilaments (hereinafter, the strands and monofilaments are collectively referred to as fine-fineness strands) are dispersed in a planar shape, such as a chopped strand mat and a continuous strand. Examples include mats, papermaking mats, carding mats, airlaid mats, and the like. A strand is a collection of a plurality of single fibers arranged in parallel and is also called a fiber bundle. In the form of the nonwoven fabric, the fineness strands usually do not have regularity in the dispersed state. By making it into the form of this nonwoven fabric, since it is excellent in shapeability, shaping | molding to a complicated shape is easy. In addition, since the voids in the nonwoven fabric complicate the progress of resin impregnation, the thermoplastic resin and the adhesive form a more complicated interface when such an integrally molded product is formed, and exhibit excellent bonding ability.

  The nonwoven fabric is more preferably a nonwoven fabric in which discontinuous reinforcing fibers are dispersed in a substantially monofilament shape. Here, the dispersion in a substantially monofilament shape means that 50% by mass or more of fineness strands having less than 100 filaments are included in discontinuous reinforcing fibers constituting the reinforcing fiber nonwoven fabric. Since the discontinuous reinforcing fibers are dispersed in a substantially monofilament shape, the steric hindrance between the reinforcing fibers becomes larger, and the anchoring structure of the reinforcing fibers and the thermoplastic resin is strong when an integrated molded product is obtained. Since it becomes a thing, it is preferable. Furthermore, because the structural unit of the fineness strand is small, a complex and dense fiber network structure is formed, and the reinforcing effect to the adhesive derived from this improves the joint strength when it is made into an integrally molded product. Is preferable. Furthermore, since the weak part is minimized at the fiber bundle end, which is often the starting point of breakage, the above-described function as a reinforcing material is enhanced, and an adhesive layer excellent in reinforcement efficiency and reliability is formed. From this viewpoint, it is preferable that 70% by mass or more of the discontinuous reinforcing fibers exist in the fineness strands having less than 100 filaments.

The filamentous state of the discontinuous reinforcing fibers constituting the reinforcing fiber nonwoven fabric is measured by the method exemplified below. The fiber reinforced resin sheet is sandwiched between metal meshes to burn off the thermoplastic resin component, and the remaining nonwoven fabric is taken out. About the nonwoven fabric taken out, after measuring the mass Wm, all the fiber bundles that are visually recognized are extracted with tweezers, and for all the fiber bundles, the length Ls is accurate to 1/100 mm and the mass Ws is 1/100 mg. Measure with accuracy. As a rule of thumb, fiber bundles that can be extracted by visual recognition are up to about 50 filaments, and most of the fiber bundles that are extracted belong to the region of 100 or more filaments, and the pieces and the remainder are less than 100. . Further, when the number of filaments calculated later is less than 100, this is excluded from the target of Ws accumulation. From the length Lsi and the mass Wsi of the fiber bundle extracted i-th (i = 1 to n), the number of filaments Fi in the fiber bundle is calculated by the following equation. Here, D in the formula is the fineness (mg / mm) of the filament.
・ Fi (book) = Wsi / (D × Lsi)

Based on the Fi calculated above, the fiber bundle is selected. FIG. 5 shows the breakdown of the mass fraction in each class as viewed by class for each 50 filaments in the nonwoven fabric constituting the fiber-reinforced resin sheet of the present invention. In FIG. 5, the mass fraction Rw (wt%) of the fiber bundle in which the ratio of the bar graph of the second class (0 to 100 filaments) from the side with the smallest number of filaments and the sum of all the bar graphs is less than 100 filaments It corresponds to. This can be calculated by the following equation using the numerical values actually measured above.
Rw (mass%) = {Wm−Σ (Wsi)} / Wm × 100

  Further, the nonwoven fabric is particularly preferably a nonwoven fabric in which discontinuous reinforcing fibers are monofilamentally and randomly dispersed. Here, “dispersed in a monofilament shape” means that the ratio of single fibers having a two-dimensional contact angle of 1 degree or more is 80% or more for discontinuous reinforcing fibers arbitrarily selected in the fiber reinforced resin sheet. In other words, it means that the bundle of two or more single fibers in contact with each other in the constituent elements is less than 20%. Therefore, here, at least the discontinuous reinforcing fibers constituting the nonwoven fabric of the fiber-reinforced resin sheet are targeted for those having a mass fraction Rw of 100 or fewer filaments corresponding to 100%.

  Here, the two-dimensional contact angle is an angle formed by the single fiber of the discontinuous reinforcing fiber in the nonwoven fabric and the single fiber in contact with the single fiber, and the angle formed by the single fibers in contact with each other. Of these, it is defined as an angle on the acute angle side of 0 degree or more and 90 degrees or less. This two-dimensional contact angle will be further described with reference to the drawings. 3 (a) and 3 (b) are one embodiment of the present invention, and are schematic views when the reinforcing fibers in the nonwoven fabric are observed from the surface direction (a) and the thickness direction (b). When the single fiber 11 is used as a reference, the single fiber 11 is observed to intersect with the single fibers 12 to 16 in FIG. 3A, but the single fiber 11 is in contact with the single fibers 15 and 16 in FIG. Not. In this case, with respect to the single fiber 11 serving as a reference, the evaluation targets of the two-dimensional contact angle are the single fibers 12 to 14, and of the two angles formed by the two single fibers that are in contact, 0 degree or more and 90 degrees. The following acute angle 17 is set.

  The method for measuring the two-dimensional contact angle is not particularly limited. For example, the method for observing the orientation of the reinforcing fibers from the surface of the fiber reinforced resin sheet or the same method as that for measuring the volume ratio Vfm of the reinforcing fibers is used. Examples of the method of observing the orientation of the reinforcing fibers using transmitted light and the method of observing the orientation of the reinforcing fibers using an optical microscope or an electron microscope can be exemplified. Furthermore, the method of photographing the orientation image of the reinforcing fiber by observing the fiber-reinforced resin sheet through X-ray CT transmission can be exemplified. Based on the observation method, the fiber dispersion rate is measured by the following procedure. Two-dimensional contact angles with all single fibers (single fibers 12 to 14 in FIG. 3) in contact with randomly selected single fibers (single fibers 11 in FIG. 3) are measured. This is performed for 100 single fibers, and the ratio is calculated from the ratio between the total number of all single fibers whose two-dimensional contact angle is measured and the number of single fibers whose two-dimensional contact angle is 1 degree or more.

  Furthermore, that the discontinuous reinforcing fibers are randomly dispersed means that the average value of the two-dimensional orientation angle of the discontinuous reinforcing fibers arbitrarily selected in the fiber reinforced resin sheet is 30 to 60 degrees. Say. The two-dimensional orientation angle is an angle formed by a single fiber of discontinuous reinforcing fibers and a single fiber intersecting with the single fiber, and 0 degree or more of angles formed by intersecting single fibers It is defined as an acute angle of 90 degrees or less. This two-dimensional orientation angle will be further described with reference to the drawings. 3A and 3B, when the single fiber 11 is used as a reference, the single fiber 11 intersects with the other single fibers 12 to 16. Crossing here means a state in which a single fiber as a reference is observed crossing another single fiber in a two-dimensional plane to be observed, and the single fiber 11 and the single fibers 12 to 16 are not necessarily in contact with each other. It is not necessary to be present, and it is no exception for the state observed when they are projected. That is, when viewed with respect to the single fiber 11 serving as a reference, all of the single fibers 12 to 16 are evaluation targets of the two-dimensional orientation angle, and the two single fibers whose two-dimensional orientation angles intersect in FIG. Among the two angles to be formed, the angle 17 is an acute angle side of 0 degree or more and 90 degrees or less.

  The method for measuring the two-dimensional orientation angle from the fiber reinforced resin sheet is not particularly limited. For example, the method for observing the orientation of the reinforcing fiber from the surface of the component can be exemplified, and the above-described method for measuring the two-dimensional contact angle. You can take similar measures. The average value of the two-dimensional orientation angle is measured by the following procedure. The average value of the two-dimensional orientation angles with all the single fibers (single fibers 12 to 16 in FIG. 3) intersecting with the randomly selected single fibers (single fibers 11 in FIG. 3) is measured. For example, when there are many other single fibers that cross a certain single fiber, an average value obtained by randomly selecting and measuring 20 other single fibers that intersect may be used instead. The measurement is repeated a total of 5 times based on another single fiber, and the average value is calculated as the average value of the two-dimensional orientation angle.

  Furthermore, the discontinuous reinforcing fibers are monofilament-like and randomly dispersed, so that the performance provided by the above-described nonwoven fabric dispersed in the substantially monofilament form can be maximized, and particularly excellent adhesion in the interface layer. It is preferable because it exhibits sex. In addition, the fiber reinforced resin sheet and an integrated molded product using the fiber reinforced resin sheet can be provided with isotropy, and it is not necessary to consider the direction of the mechanical properties in handling the fiber reinforced resin sheet. Since the internal stress in the interface layer due to directionality is small, excellent mechanical properties in the interface layer are given. From this point of view, the average value of the two-dimensional orientation angle of the reinforcing fibers is preferably 40 to 50 degrees, and it is more preferable as it approaches 45 degrees that is an ideal angle.

  The average fiber length Ln of the discontinuous reinforcing fibers is preferably in the range of 1 to 25 mm. By setting the average fiber length Ln in such a range, the reinforcing efficiency of the reinforcing fibers can be increased, and excellent mechanical properties and bonding strength can be provided in the integrally molded product including the fiber reinforced resin sheet. Moreover, adjustment of the out-of-plane angle of the reinforcing fiber in the reinforcing fiber nonwoven fabric becomes easy. For the average fiber length Ln, 400 fibers are randomly selected from the remaining reinforcing fibers after the thermoplastic resin component of the fiber reinforced resin sheet is burned off, the length is measured to the 10 μm unit, and the number average is calculated. And used as the average fiber length Ln.

  As an aspect in which the above-described function can be expressed more effectively, the out-of-plane angle θz of the reinforcing fiber in the fiber-reinforced resin sheet is preferably set to 5 ° or more. Here, the out-of-plane angle θz of the reinforcing fiber is the degree of inclination with respect to the thickness direction of the reinforcing fiber nonwoven fabric constituting the fiber reinforced resin sheet, and indicates that the larger the value is, the more inclined it is in the thickness direction, It is given in the range of 0-90 °. That is, by setting the out-of-plane angle θz of the reinforcing fiber within such a range, the above-described reinforcing function in the interface layer can be expressed more effectively, and a stronger bond can be provided by the adhesive layer. The upper limit value of the out-of-plane angle θz of the reinforcing fiber is not particularly limited, but is preferably 15 ° or less, more preferably 10 ° or less from the viewpoint of handleability when the fiber-reinforced resin sheet is used.

  Here, a method of measuring the out-of-plane angle θz of the reinforcing fiber based on observation of a vertical cross section with respect to the surface direction of the fiber reinforced resin sheet can be exemplified. FIG. 4 shows a vertical cross section (a) with respect to the surface direction of the fiber-reinforced resin sheet to be measured and its depth direction (b). In FIG. 4A, the cross-sections of the reinforcing fibers 19 and 20 are approximated to an elliptical shape for easy measurement. Here, the cross section of the reinforcing fiber 19 has a small elliptical aspect ratio (= ellipse long axis / short elliptical axis), whereas the cross section of the reinforcing fiber 20 has a large elliptical aspect ratio. On the other hand, according to FIG. 4B, the reinforcing fiber 19 has a substantially parallel inclination with respect to the depth direction Y, and the reinforcing fiber 20 has a certain amount of inclination with respect to the depth direction Y. 4A, the angle θx formed by the surface direction X of the fiber-reinforced resin sheet and the fiber principal axis (long axis direction in the ellipse) α is the out-of-plane angle θz of the reinforcing fiber. Is almost equal to On the other hand, the reinforcing fiber 6 has a large difference between the angle θx and the angle indicated by the out-of-plane angle θz, and it cannot be said that the angle θx reflects the out-of-plane angle θz. Accordingly, when the out-of-plane angle θz is read from a vertical cross section with respect to the surface direction of the fiber reinforced resin sheet, the detection accuracy of the out-of-plane angle θz can be increased by extracting the out-of-plane angle θz having a certain cross-sectional elliptical aspect ratio. .

  Here, as an index of the elliptical aspect ratio to be extracted, the cross-sectional shape of the single fiber is close to a perfect circle, that is, when the fiber aspect ratio in the cross section perpendicular to the longitudinal direction of the reinforcing fiber is 1.1 or less, For a reinforcing fiber having an elliptical aspect ratio of 20 or more, a method of measuring the angle formed by the X direction and the fiber principal axis α and adopting this as the out-of-plane angle θz can be used. On the other hand, if the cross-sectional shape of the single fiber is an ellipse or a saddle, etc., and the fiber aspect ratio is greater than 1.1, pay attention to the reinforcing fiber having a larger elliptical aspect ratio and measure the out-of-plane angle When the fiber aspect ratio is 1.1 or more and less than 1.8, the elliptical aspect ratio is 30 or more. When the fiber aspect ratio is 1.8 or more and less than 2.5, the elliptical aspect ratio is 40 or more. When the aspect ratio is 2.5 or more, it is preferable to select a reinforcing fiber having an elliptical aspect ratio of 50 or more and measure the out-of-plane angle θz.

  In the present invention, examples of reinforcing fibers constituting the reinforcing fiber nonwoven fabric include metal fibers such as aluminum, brass, and stainless steel, polyacrylonitrile (PAN) -based, rayon-based, lignin-based, pitch-based carbon fibers, and graphite fibers. Insulating fibers such as glass, organic fibers such as aramid, PBO, polyphenylene sulfide, polyester, acrylic, nylon, and polyethylene, and inorganic fibers such as silicon carbide and silicon nitride. Moreover, the surface treatment may be given to these fibers. Examples of the surface treatment include a treatment with a coupling agent, a treatment with a sizing agent, a treatment with a binding agent, and an adhesion treatment of an additive in addition to a process for depositing a metal as a conductor. Moreover, these reinforcing fibers may be used individually by 1 type, and may use 2 or more types together. Among these, PAN-based, pitch-based, and rayon-based carbon fibers that are excellent in specific strength and specific rigidity are preferably used from the viewpoint of weight reduction effect. In addition, glass fibers are preferably used from the viewpoint of improving the economical efficiency of the resulting molded article, and it is particularly preferable to use carbon fibers and glass fibers in combination from the balance of mechanical properties and economic efficiency. Furthermore, aramid fibers are preferably used from the viewpoint of improving the impact absorbability and formability of the obtained molded product, and it is particularly preferable to use carbon fibers and aramid fibers in combination from the balance of mechanical properties and impact absorbability. Further, from the viewpoint of improving the conductivity of the obtained molded product, reinforcing fibers coated with a metal such as nickel, copper, ytterbium, etc. can also be used. Among these, PAN-based carbon fibers having excellent mechanical properties such as strength and elastic modulus can be more preferably used.

  Examples of the thermoplastic resin constituting the fiber-reinforced resin sheet of the present invention include “polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); and polyolefins such as polyethylene (PE), polypropylene (PP), and polybutylene. And polyarylene sulfides such as polyoxymethylene (POM), polyamide (PA), polyphenylene sulfide (PPS), polyketone (PK), polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone ( PEKK), fluororesins such as polytetrafluoroethylene, crystalline resins such as liquid crystal polymer (LCP), “styrene resins, polycarbonate (PC), polymethyl methacrylate (PMMA), polysalts” Amorphous such as vinyl (PVC), polyphenylene ether (PPE), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polysulfone (PSU), polyethersulfone, polyarylate (PAR) Resins, other phenolic resins, phenoxy resins, polystyrene-based, polyolefin-based, polyurethane-based, polyester-based, polyamide-based, polybutadiene-based, polyisoprene-based, fluorine-based resins, acrylonitrile-based thermoplastic elastomers, etc. And thermoplastic resins selected from copolymers, modified products, and the like. Among these, polyolefin is preferable from the viewpoint of light weight of the obtained molded product, polyamide and polyester are preferable from the viewpoint of strength, amorphous resin such as polycarbonate is preferable from the viewpoint of surface appearance, and poly-resin from the viewpoint of heat resistance. Arylene sulfide and polyether ketone are preferably used.

  Examples of the adhesive constituting the fiber reinforced resin sheet of the present invention include an epoxy resin adhesive, a polyester adhesive, a rubber adhesive, a urethane resin adhesive, an acrylic resin adhesive, and a urea resin adhesive. An adhesive selected from phenol resin adhesives and melamine resin adhesives can be used. Of these, epoxy resin adhesives and urethane resin adhesives are preferably used because of their handleability and variety.

  The thermoplastic resin and the adhesive may contain an impact resistance improver such as an elastomer or a rubber component, and other fillers and additives as long as the object of the present invention is not impaired. Examples of these include inorganic fillers, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, heat stabilizers. , Antistatic agents, plasticizers, lubricants, colorants, foaming agents, antifoaming agents, or coupling agents.

Next, a method for efficiently producing the fiber reinforced resin sheet of the present invention will be described. As a method for producing the fiber reinforced resin sheet of the present invention, it is preferable to have the following steps (I) and (II).
(I) While impregnating the thermoplastic resin on one side in the thickness direction of the nonwoven fabric composed of reinforcing fibers, and on the other side in the thickness direction of the nonwoven fabric, a region where the reinforcing fibers constituting the nonwoven fabric are exposed, Step of forming the reinforcing fiber so that the volume ratio Vfm of the reinforcing fiber in the region is 20% by volume or less (II) Step of impregnating the region in which the reinforcing fiber constituting the nonwoven fabric is exposed with an adhesive

  For example, a nonwoven fabric in which reinforcing fibers are dispersed in the form of strands and / or monofilaments is manufactured in advance, and one side in the thickness direction of the nonwoven fabric is first impregnated with a thermoplastic resin. The manufacturing method of the reinforced fiber nonwoven fabric includes a dry process such as an airlaid method in which the reinforced fiber is dispersed in an air stream, a carding method in which the reinforced fiber is formed by mechanically scraping the sheet, and the reinforced fiber is submerged in water. As a known technique, a wet process based on a radrite method in which paper is made by stirring with a paper can be cited. As means for bringing the reinforcing fibers closer to a monofilament in the above, in the dry process, a method of providing a fiber opening bar, a method of further vibrating the fiber opening bar, a method of further finening the card eye, a card rotation speed, A method for adjusting the value can be exemplified. In the wet process, there are a method of adjusting the stirring condition of the reinforcing fiber, a method of diluting the reinforcing fiber concentration of the dispersion, a method of adjusting the viscosity of the dispersion, and a method of suppressing the vortex when the dispersion is transferred. It can be illustrated. In particular, it is preferably manufactured by a wet method, and the volume ratio Vfm of the reinforcing fiber in the reinforcing fiber nonwoven fabric is increased by increasing the concentration of the input fiber, or adjusting the flow rate (flow rate) of the dispersion and the speed of the mesh conveyor. It can be adjusted easily. For example, by slowing the speed of the mesh conveyor with respect to the flow rate of the dispersion liquid, the orientation of the fibers in the obtained reinforcing fiber nonwoven fabric becomes difficult to take in the take-up direction, and a bulky reinforcing fiber nonwoven fabric can be produced. Reinforcing fiber nonwoven fabric may be composed of reinforcing fiber alone, reinforcing fiber is mixed with powder or fiber shaped matrix resin component, reinforcing fiber is mixed with organic compound or inorganic compound, reinforcing The fibers may be sealed with a resin component.

  By using the reinforcing fiber nonwoven fabric and impregnating a thermoplastic resin on one side of the nonwoven fabric, a region where the reinforcing fibers constituting the nonwoven fabric are exposed on the other side of the nonwoven fabric is formed. Further, by setting the volume ratio of the reinforcing fiber in the region where the reinforcing fiber is exposed to 20% by volume or less, there is no excessive reinforcing fiber on the exposed surface of the reinforcing fiber. Since the ease of impregnation of the agent is improved, the production of the fiber reinforced resin sheet becomes easy and the process stability is excellent. Specifically, a method of melt impregnating a thermoplastic resin in a state where the thermoplastic resin is arranged on one side in the thickness direction of the reinforcing fiber nonwoven fabric can be exemplified. Moreover, as equipment for realizing the above method, a compression molding machine, a double belt press, and a calender roll can be suitably used. In the case of a batch type, the former, the productivity can be improved by using an intermittent press system in which two machines for heating and cooling are arranged in parallel. In the case of a continuous type, the latter, which can be easily processed from roll to roll, and is excellent in continuous productivity. In addition, since the volume ratio of the reinforcing fiber in the region where the reinforcing fiber is exposed matches the volume ratio Vfm of the reinforcing fiber in the nonwoven fabric, it can be specified by measuring the volume ratio Vfm of the reinforcing fiber in the nonwoven fabric. In the obtained sheet, a region where the reinforcing fibers constituting the nonwoven fabric are exposed may be cut out, and the volume ratio of the reinforcing fibers in the region may be measured by the same method as the volume ratio Vfm of the reinforcing fibers in the nonwoven fabric.

  Subsequent to the step (I), the fiber reinforced resin sheet of the present invention is obtained by impregnating the region where the reinforcing fibers constituting the nonwoven fabric are exposed with an adhesive. The step of impregnating with such an adhesive (Step (II) is the step of disposing the reinforcing fiber on the surface where the reinforcing fiber constituting the reinforcing fiber non-woven fabric is exposed, with an amount of the adhesive not exceeding 20% by volume of the reinforcing fiber. It is preferable to impregnate so that air bubbles do not enter between the exposed surface and the adhesive from the viewpoint of ensuring the ease of the bonding process when used for bonding with other materials and the bonding strength with other materials. Specifically, there can be exemplified a method of heating and pressurizing and melt impregnating a film-like or lump-like adhesive on the fiber-exposed side of the sheet obtained in step (I) in the thickness direction. As the equipment for realizing the above method, a vacuum forming machine, a double belt press, and a calender roll can be suitably used. Resin It can be selected device on the same basis a step of immersed.

  In the present invention, an integrated molded product is obtained by bonding the first member including the above-described fiber-reinforced resin sheet and the second member made of metal with an adhesive in the fiber-reinforced resin. That is, the first member is bonded to the second member by means of heating and pressurizing in a state where the adhesive layer in the first member and the second member are in contact with each other.

  The fiber-reinforced resin sheet of the present invention is an adherend because the anchoring effect of the thermoplastic resin layer and the adhesive layer in the sheet and the shear strength of the adhesive layer is reinforced by the single fibers of the reinforcing fibers. Excellent adhesion and bondability with metal materials.

  The metal is not particularly limited, and examples thereof include at least one selected from the group consisting of aluminum, magnesium, titanium, iron, copper, and alloys containing any of them. These metal materials can be selected according to the intended use and physical properties. For example, aluminum and aluminum alloys containing aluminum include A1050, A1100, A1200, and Al-Cu of industrial pure aluminum. Series A2017, A2024, Al-Mn series A3003, A3004, Al-Si series A4032, Al-Mg series A5005, A5052, A5083, Al-Mg-Si series A6061, A6063, Al-Zn series A7075 Etc.

  Examples of magnesium and magnesium alloys containing magnesium include Mg-Al-Zn-based AZ31, AZ61, and AZ91. As for pure magnesium, a plate-like one is poorly distributed, and a magnesium alloy is generally used.

  Titanium and titanium alloys containing titanium include 1 to 4 types of industrial pure titanium, alloys added with 11 to 23 types of palladium, alloys added with cobalt and palladium, 50 types (α alloy), Examples include Ti-6Al-4V corresponding to 60 types (α-β alloy) and 80 types (β alloy).

  Examples of iron and iron-containing alloys include SPHC, SPKH, and S-C, which are hot-rolled steel sheets for automobiles. Moreover, stainless steel to which chromium, nickel, or the like is added, for example, SUS304, SUS405, or the like can be exemplified.

  Examples of copper and copper-containing alloys include systems in which Fe, Pb, and Al are added in addition to pure copper, such as C1100, C2720, and C6140. Such a metal material can be preferably used as a member or component of various products because it has a practical bonding strength by being integrated with the fiber reinforced resin sheet of the present invention.

  In order to obtain such an integrally molded product, the means for joining the first member and the second member is not particularly limited. For example, as a general means having heating and pressing, a press molding method can be exemplified. As the press molding method, the mold is heated in advance to the curing temperature of the adhesive, and the first member (fiber reinforced resin sheet) and the second member (made of metal are formed in the heated mold. There is a so-called hot press molding method in which a molded product is obtained by placing and clamping the mold and pressurizing it, and then cooling the mold while maintaining the state. Further, it is possible to adopt a method in which the surface on which the adhesive layer is present and the adherend are brought into close contact with each other by vacuum pressure or mechanical fastening, and heating and pressurization are continued until the adhesive is cured.

  Examples of the use of the mounting member provided by the fiber reinforced resin sheet of the present invention and the integrated molded product made of the fiber reinforced resin sheet include: ), Video camera, optical equipment, audio, air conditioner, lighting equipment, entertainment equipment, toy goods, other housings such as home appliances, trays, chassis, interior parts, or their case ", etc.," various `` Members, various frames, various hinges, various arms, various axles, various wheel bearings, various beams '', `` hood, roof, door, fender, trunk lid, side panel, rear end panel, front body, underbody, various pillars, Various members, various frames, various beams, various supports, various rails, various Outer panel or body parts such as engine parts, "bumper, bumper beam, molding, under cover, engine cover, current plate, spoiler, cowl louver, aero parts, etc.", "instrument panel, seat frame, door trim" , Interior parts such as pillar trim, steering wheel and various modules "or" motor parts, CNG tanks, gasoline tanks "and other automobile and motorcycle structural parts," others, battery tray, headlamp support, pedal housing, protector, lamp reflector " , Lamp housing, noise shield, spare tire cover "and other parts for automobiles, motorcycles, aviation such as" landing gear pod, winglet, spoiler, edge, ladder, elevator, failing, rib " Use parts and the like. From the viewpoint of mechanical properties, it is preferably used for automobile interior and exterior, electrical / electronic equipment housings, bicycles, sports equipment structural materials, aircraft interior materials, and transport boxes. Especially, it is suitable for the module member comprised from a some component especially.

  Hereinafter, the present invention will be described in more detail with reference to examples.

(1) Volume ratio Vfm of reinforcing fiber in the region where reinforcing fiber is exposed
Apply a razor between the end impregnated with thermoplastic resin and the exposed reinforcing fiber from a sheet of thermoplastic fiber impregnated on one side of the reinforcing fiber nonwoven fabric, carefully separate the exposed reinforcing fiber part and sandwich it with a stainless steel mesh This was used as a sample. For the sample, the thickness after applying 20 kPa for 20 seconds was measured according to JIS R7602 (1995) and measured in advance under the same conditions. The value obtained by subtracting the thickness of the stainless steel mesh was defined as the thickness tm of the reinforcing fiber nonwoven fabric. Further, after removing the stainless steel mesh from the sample, the mass Wm per unit area was measured in accordance with “Method for measuring weight per unit area of carbon fiber fabric” defined in JIS R7602 (1995). The volume ratio Vfm of the reinforcing fiber was calculated from the obtained Wm and tm by the following formula.
Vfm (volume%) = (Wm / ρf) / (S × tm) × 100
ρf: density of reinforcing fiber (g / cm ³ )
S: Sample cut-out area (cm ² )

(2) Volume ratio Vf of reinforcing fiber in fiber reinforced resin sheet
After measuring the mass Ws of the fiber reinforced resin sheet, the fiber reinforced resin sheet is heated in air at 500 ° C. for 30 minutes to burn off the thermoplastic resin component and the adhesive component, and the mass Wf of the remaining reinforced fiber nonwoven fabric is measured. And calculated by the following formula.
Vf (volume%) = (Wf / ρf) / {Wf / ρf + (Ws−Wf) / ρr} × 100
ρf: density of reinforcing fiber (g / cm ³ )
ρr: Total density of thermoplastic resin and adhesive (g / cm ³ ).

(3) Uneven shape (Ry, Rz) in the interface layer of the fiber reinforced resin sheet
The adhesive was cured at a temperature at which the thermoplastic resin did not melt in the fiber reinforced resin sheet. Thereafter, a small piece having a width of 25 mm was cut out from the fiber-reinforced resin sheet cured with the adhesive, embedded in an epoxy resin, and polished so that a vertical cross section in the thickness direction became an observation surface to prepare a sample. The sample was magnified 200 times with a laser microscope (manufactured by Keyence Corporation, VK-9510), and photographed at 10 randomly selected locations (the fields of view did not overlap each other). From the photographed image, the interface layer formed by the thermoplastic resin and the adhesive was confirmed by the contrast of the resin. When the contrast was unclear, the shading was clarified by image processing. Of the ten fields captured above, of the uneven interfaces in each field of view, the vertical drop dmax between the concave part with the largest depression and the convex part with the largest protrusion, the concave part with the smallest depression and the convex part with the smallest protrusion. The vertical drop dmin was measured. Of the 10 dmax values in each field of view, the largest value was taken as the maximum height Ry (μm) of the concavo-convex shape in the interface layer. Further, from the dmax and dmin obtained above, the average roughness Rz of the uneven shape in the interface layer was calculated by the following equation.
Rz (μm) = Σ (dimax + dimin) / 2n
dimax: Maximum vertical drop in each field of view (i = 1, 2,... 10) (μm)
dimin: Minimum vertical drop in each field of view (i = 1, 2,... 10) (μm)
n: Number of viewing fields

(4) Mass fraction (Rw) of the fineness strand in the reinforcing fiber nonwoven fabric
In the same manner as in (2) above, the reinforcing fiber nonwoven fabric was taken out from the fiber reinforced resin sheet, and the mass Wm was measured. Subsequently, the fiber bundle to be visually recognized was extracted from the reinforcing fiber nonwoven fabric with tweezers, and the fiber bundle length Ls was measured with an accuracy of 1/100 mm and the mass Ws of the fiber bundle was measured with an accuracy of 1/100 mg. This was repeated for all the fiber bundles (n) present in the reinforcing fiber nonwoven fabric. From the length Ls and mass Ws of the obtained fiber bundle, the number of filaments F in the fiber bundle was calculated by the following formula.
・ Fi (book) = Wsi / (D × Lsi)
Fi: Individual value (number) of the number of filaments in the fiber bundle (i = 1 to n)
Wsi: mass of fiber bundle (mg)
Lsi: Length of fiber bundle (mm)
D: Fineness per filament (mg / mm)

Based on the Fi calculated above, a fiber bundle having 100 or more filaments was selected. From the mass Wi of the selected fiber bundle, the mass fraction Rw of the fiber bundle having the number of filaments of less than 100 was calculated by the following formula.
Rw (mass%) = {Wm−Σ (Wsi)} / Wm × 100
Wm: mass of the reinforcing fiber nonwoven fabric (mg)

(5) Fiber dispersion rate of reinforcing fiber nonwoven fabric The reinforcing fiber nonwoven fabric was taken out of the fiber reinforced resin sheet by the same method as in (2) above. The obtained reinforcing fiber nonwoven fabric is observed using an electron microscope (VHX-500, manufactured by Keyence Corporation), one single fiber is randomly selected, and another single fiber is in contact with the single fiber. The dimensional contact angle was measured. As the two-dimensional contact angle, an angle (acute angle side) of 0 ° or more and 90 ° or less among two angles formed by two single fibers in contact with each other was adopted. The measurement of the two-dimensional contact angle was performed on 100 single fibers, targeting all single fibers that contact the selected single fibers. From the obtained results, the ratio was calculated from the total number of all single fibers whose two-dimensional contact angle was measured and the number of single fibers whose two-dimensional contact angle was 1 degree or more, and the fiber dispersion rate was obtained. .

(6) Two-dimensional orientation angle of reinforced fiber nonwoven fabric The reinforced fiber nonwoven fabric was taken out from the fiber reinforced resin sheet by the same method as in (2) above. The obtained reinforcing fiber non-woven fabric was observed using an electron microscope (VHX-500, manufactured by Keyence Corporation), one single fiber was randomly selected, and another single fiber crossing the single fiber was selected. The dimensional orientation angle was measured by image observation. Of the two angles formed by the two intersecting single fibers, the angle between 0 ° and 90 ° (acute angle side) was adopted as the orientation angle. The number of measured two-dimensional orientation angles per selected single fiber was n = 20. The same measurement was performed by selecting a total of 5 single fibers, and the average value was taken as the two-dimensional orientation angle.

(7) Out-of-plane angle θz of reinforcing fiber in fiber-reinforced resin sheet
The adhesive was cured at a temperature at which the thermoplastic resin did not melt in the fiber reinforced resin sheet. Thereafter, a small piece having a width of 25 mm was cut out from the fiber-reinforced resin sheet cured with the adhesive, embedded in an epoxy resin, and polished so that a vertical cross section in the thickness direction became an observation surface to prepare a sample. The sample was magnified 400 times with a laser microscope (manufactured by Keyence Corporation, VK-9510), and the fiber cross-sectional shape was observed. The observation image is developed on general-purpose image analysis software, and individual fiber cross sections that are visible in the observation image are extracted using a program incorporated in the software, and an ellipse that inscribes the fiber cross section is provided to approximate the shape ( Hereinafter referred to as a fiber ellipse). Further, for the fiber ellipse having an aspect ratio of 20 or more represented by the major axis length α / minor axis length β of the fiber ellipse, the angle formed by the X axis direction and the major axis direction of the fiber ellipse was determined. By repeating the above operation for observation samples extracted from different parts of the fiber reinforced resin sheet, the out-of-plane angle was measured for a total of 600 reinforced fibers, and the average value was obtained as the out-of-plane angle θz of the fiber reinforced resin sheet. .

(8) Joint strength τ2 of the joint in the integrally molded product
The joint strength τ2 of the joint part in the integrally molded product was evaluated with reference to the “Testing method for tensile shear bond strength of adhesive-rigid adherend” defined in JIS K6850 (1999). As the test piece in this test, an integrated molded product obtained in the example was cut out and used. The test piece is shown in FIG. The test piece 21 is formed with a joint between the first member and the second member at a position 1/2 inch from the center of the length l and the width w. Five test pieces were prepared, and a tensile test was performed using a universal testing machine (manufactured by Instron, universal testing machine 4201). The average value of all data (n = 5) obtained by the test was defined as the joint strength τ2 (MPa) of the joint in the integrally molded product.

(9) Penetration of reinforcing fiber in interface layer of thermoplastic resin and adhesive The adhesive was cured at a temperature at which the thermoplastic resin did not melt in the fiber reinforced resin sheet. Thereafter, a small piece having a width of 25 mm was cut out from the fiber-reinforced resin sheet cured with the adhesive, embedded in an epoxy resin, and polished so that a vertical cross section in the thickness direction became an observation surface to prepare a sample. The said sample was expanded 400 times with the laser microscope (the Keyence Corporation make, VK-9510), and the penetration state of the reinforced fiber was observed. The determination of the penetration state was made by observing the same portion every time the sample cross section was polished every 100 μm, and using the determination criteria as to whether or not the reinforced fibers exist across the thermoplastic resin layer and the adhesive layer. Moreover, in observation, the above operation was repeated for observation samples extracted from different parts of the fiber reinforced resin sheet, whereby a total of 10 visual fields were observed, and the presence or absence of penetration of reinforcing fibers was determined.

[Reinforcing fiber 1]
Spinning and firing were performed from a polymer containing polyacrylonitrile as a main component to obtain continuous carbon fibers having a total filament number of 12,000. Further, the continuous carbon fiber was subjected to electrolytic surface treatment and dried in heated air at 120 ° C. to obtain reinforcing fiber 1. The characteristics of this carbon fiber 1 were as follows.
Density: 1.80 g / cm ³
Single fiber diameter: 7μm
Tensile strength: 4.9 GPa
Tensile modulus: 230 GPa

[Resin sheet 1]
90% by mass of unmodified polypropylene resin (manufactured by Prime Polymer Co., Ltd., “Prime Polypro” (registered trademark) J106MG) and 10 mass of acid-modified polypropylene resin (manufactured by Mitsui Chemicals, Inc., “Admer” (registered trademark) QE800) A sheet having a basis weight of 100 g / m ² was prepared using a master batch consisting of%. The properties of the obtained resin sheet are shown in Table 1.

[Resin sheet 2]
A resin film having a basis weight of 124 g / m ² made of polyamide 6 resin (“Amilan” (registered trademark) CM1021T manufactured by Toray Industries, Inc.) was produced. The properties of the obtained resin sheet are shown in Table 1.

[Resin sheet 3]
A resin film having a basis weight of 132 g / m ² made of polycarbonate resin (“Iupilon” (registered trademark) H-4000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was produced. The properties of the obtained resin sheet are shown in Table 1.

[Resin sheet 4]
A resin nonwoven fabric having a basis weight of 67 g / m ² made of polyphenylene sulfide resin (“Torelina” (registered trademark) M2888 manufactured by Toray Industries, Inc.) was produced. The properties of the obtained resin sheet are shown in Table 1.

[6mm mat]
Reinforcing fiber 1 was cut to 6 mm with a cartridge cutter to obtain chopped reinforcing fiber. 40 liters of a dispersion medium having a concentration of 0.1% by mass made of water and a surfactant (manufactured by Nacalai Tesque Co., Ltd., polyoxyethylene lauryl ether (trade name)) was prepared, and the dispersion medium was put into a papermaking apparatus. The papermaking apparatus is composed of an upper papermaking tank (capacity 30 liters) equipped with a stirrer with rotating blades and a lower water storage tank (capacity 10 liters), and a porous support is provided between the papermaking tank and the water storage tank. . First, the dispersion medium was stirred with a stirrer until air microbubbles were generated. Thereafter, the chopped reinforcing fibers whose masses were adjusted so as to have a desired basis weight were put into a dispersion medium in which fine air bubbles were dispersed and stirred to obtain a slurry in which the reinforcing fibers were dispersed. Next, the slurry was sucked from the water storage layer and dehydrated through a porous support to obtain a reinforced fiber sheet. The papermaking product was dried in a hot air dryer at 150 ° C. for 2 hours to obtain a 6 mm mat having a basis weight of 100 g / m ² . The characteristics are shown in Table 2.

[3mm mat]
A 3 mm mat was obtained in the same manner as the 6 mm mat, except that the fiber length of the reinforcing fiber used for the reinforcing fiber nonwoven fabric was 3 mm. The characteristics are shown in Table 2.

[25mm mat]
A 25 mm mat was obtained in the same manner as the 6 mm mat except that the fiber length of the reinforcing fiber used for the reinforcing fiber nonwoven fabric was 25 mm. The characteristics are shown in Table 2.

[Strand mat]
Reinforcing fiber 1 was cut to 25 mm with a cartridge cutter to obtain chopped reinforcing fiber. The obtained chopped reinforcing fibers were freely dropped from a height of 80 cm to obtain a strand mat in which chopped carbon fibers were randomly distributed. The characteristics are shown in Table 2.

[Textile base material]
The reinforcing fibers 1 were aligned in parallel and arranged in one direction at a density of 1.2 fibers / cm to form a sheet-like reinforcing fiber group. The reinforcing fibers 1 were arranged at a density of 1.2 fibers / cm in a direction perpendicular to the reinforcing fiber group, the reinforcing fibers 1 were interlaced, and a bi-directional woven fabric having a plain weave structure was formed using a loom. The bidirectional fabric was handled as a fabric substrate. The characteristics are shown in Table 2.

Example 1
A resin sheet 1 as a 6 mm mat and a thermoplastic resin was placed in the order of [resin sheet 1/6 mm mat / resin sheet 1/6 mm mat / resin sheet 1/6 mm mat / 6 mm mat] to prepare a laminate.

  The laminated body is placed in a press molding die cavity preheated to 230 ° C., and the die is closed and held for 120 seconds. Then, a pressure of 3 MPa is applied and the pressure is held for another 60 seconds. Then, the cavity temperature was cooled to 50 ° C., the mold was opened, and a fiber reinforced resin sheet with reinforcing fibers exposed on one side in the thickness direction was obtained.

  By applying “Chemit” TE2220 manufactured by Toray Fine Chemical Co., Ltd. as an adhesive to the exposed surface of the reinforced fiber sheet of the obtained fiber reinforced resin sheet, the pressure of the fiber reinforced sheet is reduced by vacuum for 30 minutes. The surface where the reinforcing fibers were exposed was impregnated with an adhesive.

  Next, the fiber-reinforced resin sheet impregnated with the adhesive is pressure-bonded to a metal material (aluminum, A5052) as a second member so that the adhesive surface becomes a bonding surface, and an integrated molded product shown in FIG. 6 is obtained. It was. At this time, the adhesive was cured by leaving it at 23 ° C. for 24 hours. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 2)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 2 is used as the thermoplastic resin instead of the resin sheet 1 and the preheating temperature of the laminate is 240 ° C. An integrally molded product was obtained by the method described above. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 3)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 3 is used instead of the resin sheet 1 as a thermoplastic resin, and the preheating temperature of the laminate is 280 ° C. An integrally molded product was obtained by the method described above. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

Example 4
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 4 is used in place of the resin sheet 1 as the thermoplastic resin, and the preheating temperature of the laminate is 280 ° C. An integrally molded product was obtained by this method. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 5)
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that a 3 mm mat was used instead of the 6 mm mat as the reinforcing fiber nonwoven fabric, and an integrated molded product was obtained in the same manner as in Example 1. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 6)
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that stainless steel SUS304 was used instead of aluminum A5052 as the second member, and an integrally molded product was obtained in the same manner as in Example 1. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 7 reference example )
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that magnesium AZ31 was used instead of aluminum A5052 as the second member, and an integrally molded product was obtained in the same manner as in Example 1. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

Example 8 Reference Example
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that copper C-1100 is used instead of aluminum A5052 as the second member, and an integrated molded product is obtained in the same manner as in Example 1. It was. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

( Reference Example of Example 9)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that copper C-1100 is used instead of aluminum A5052 as the second member, and an integrated molded product is obtained in the same manner as in Example 1. It was. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 10)
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that a 25 mm mat was used instead of the 6 mm mat as the reinforcing fiber nonwoven fabric, and an integrated molded product was obtained in the same manner as in Example 1. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 11)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 2 is used instead of the resin sheet 1 as the thermoplastic resin and the preheating temperature of the laminate is 240 ° C. Further, Nagase is used as the adhesive. An integrally molded product was obtained in the same manner as in Example 1 except that “DENATITE” (registered trademark) 3324 manufactured by Chemtech Co., Ltd. was used. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 12)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 3 is used instead of the resin sheet 1 as the thermoplastic resin, and the preheating temperature of the laminate is 280 ° C. An integrated molded product was obtained in the same manner as in Example 1 except that “PLEXUS” (registered trademark) 310 manufactured by Performance and Fluids Japan Co., Ltd. was used. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Example 13)
A fiber reinforced resin sheet is obtained in the same manner as in Example 1 except that the resin sheet 4 is used instead of the resin sheet 1 as the thermoplastic resin, and the preheating temperature of the laminate is 280 ° C. Further, as the adhesive, Huntsman An integrated molded product was obtained in the same manner as in Example 1 except that “Araldite” (registered trademark) 2018 manufactured by Japan Co., Ltd. was used. Table 3 shows the characteristics of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Comparative Example 1)
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that a woven fabric substrate was used instead of the 6 mm mat as the reinforcing fiber nonwoven fabric, and an integrated molded product was obtained in the same manner as in Example 1. Table 4 summarizes the properties of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Comparative Example 2)
The configuration of the laminate of the reinforcing fiber nonwoven fabric and the resin sheet is arranged in the order of [resin sheet 1/6 mm mat / resin sheet 1/6 mm mat / 6 mm mat / resin sheet 1/6 mm mat / resin sheet 1], and the laminate Except for the production, heating and pressurization were performed in the same manner as in Example 1 to obtain a fiber-reinforced resin sheet having a reinforcing fiber exposure ratio of 0% by volume, and an integrated molded product was obtained in the same manner as in Example 1. It was. Table 4 summarizes the properties of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

(Comparative Example 3)
A fiber reinforced resin sheet was obtained in the same manner as in Example 1 except that a strand mat was used instead of the 6 mm mat as the reinforcing fiber nonwoven fabric, and an integrated molded product was obtained in the same manner as in Example 1. Table 4 summarizes the properties of the obtained fiber reinforced resin sheet (first member) and the integrally molded product.

  In each of Examples 1 to 13, it is possible to obtain a fiber-reinforced resin sheet in which various resin sheets are impregnated on one side within an appropriate range of the reinforcing fiber exposure ratio Vfm, thereby sufficiently reinforcing the nonwoven fabric with the reinforcing fiber. An adhesive-impregnated fiber reinforced sheet impregnated inside was obtained. Furthermore, by observing a cross section in the thickness direction of these fiber reinforced resin sheets with an optical microscope, it was confirmed that the reinforced fiber nonwoven fabric penetrated both the adhesive layer and the thermoplastic resin layer. In addition, the integrated molded product with the metal material (second member) obtained by using the sheet was able to give sufficient shear strength to the adhesive by the reinforcing fiber based on the reinforcing fiber nonwoven fabric. Thus, it was possible to obtain an integrally molded product excellent in adhesion / bondability with a metal material and to obtain a fiber-reinforced resin sheet of any type.

  This is because the voids in the reinforced fiber nonwoven fabric promote complex infiltration of the adhesive, and the ideal height of the interface layer is increased by increasing the maximum height Ry and average roughness Rz of the interface layer to a sufficient size. This is because, in addition to being formed, the out-of-plane angle θz of the reinforcing fiber is also in a suitable mode, and thus the second member and the fiber-reinforced resin sheet form a good interface layer.

  On the other hand, since the woven fabric base material is used in the comparative example 1, the reinforcing fibers are present in a bundled and continuous state in the comparative example 3, so that the adhesion with the second member is ensured. The agent was not sufficiently impregnated and the bonding strength was insufficient. In Comparative Example 2, a reinforced fiber nonwoven fabric (6 mm mat) was used. However, since there was no exposure of the reinforced fiber, there was no fiber based on the reinforced fiber in the adhesive, and the shear strength of the adhesive was low. The joint strength of the integrally molded product was insufficient.

  According to the fiber-reinforced resin sheet of the present invention, the anchoring effect caused by the adhesive impregnated in the exposed reinforcing fiber has a strong shear strength at the interface of the joint portion, so that the combination with the metal material to be applied is special. Without limitation, it is possible to easily obtain a hybrid body of different members of a fiber reinforced composite material and a metal material. Therefore, it can be suitably used for a wide range of applications such as automobile interior and exterior, electrical / electronic equipment casings, bicycles, structural materials for sporting goods, aircraft interior materials, and transport boxes.

1, 5, 18 Fiber reinforced resin sheet 2, 11, 12, 13, 14, 15, 16, 19, 20 Reinforcing fiber (single fiber)
DESCRIPTION OF SYMBOLS 3 Thermoplastic resin impregnated layer in fiber reinforced resin sheet 4 Adhesive impregnated layer in fiber reinforced resin sheet 6 Thermoplastic resin 7 Adhesive 8 Convex part with the largest depression in the interface layer 9 Recessed part with the largest protrusion in the interface layer 10 Interface layer Convex part with the smallest depression in 11 Eleventh part with the smallest protrusion in the interface layer 17 Two-dimensional contact angle, two-dimensional orientation angle 21 Specimen for evaluation of shear strength τ2 22 First member 23 Second member

Claims (13)

A fiber reinforced resin sheet in which a thermoplastic resin is impregnated on one side in the thickness direction of a nonwoven fabric composed of reinforcing fibers and an adhesive is impregnated on the other side in the thickness direction of the nonwoven fabric. The reinforcing fibers constituting the nonwoven fabric penetrate into both the layer impregnated with the thermoplastic resin and the layer impregnated with the adhesive, and in the sheet, the thermoplastic resin and the adhesive maximum height Ry50μm above, ing to form an interface layer having an average roughness Rz30μm more irregularities, fiber-reinforced resin sheet. The fiber-reinforced resin sheet according to claim 1, wherein a volume ratio Vfm of reinforcing fibers in the adhesive layer is 20% by volume or less. The fiber reinforced resin sheet according to claim 1 or 2 , wherein the non-woven fabric comprises discontinuous reinforcing fibers dispersed in a substantially monofilament shape. The fiber-reinforced resin sheet according to any one of claims 1 to 3 , wherein an out-of-plane angle θz of the reinforcing fiber in the sheet is in a range of 5 ° or more and 15 ° or less. The fiber-reinforced resin sheet according to any one of claims 1 to 4 , wherein the length of the reinforcing fibers constituting the nonwoven fabric is 1 mm or more and less than 10 mm. The fiber-reinforced resin sheet according to any one of claims 1 to 5 , wherein the reinforcing fibers constituting the nonwoven fabric are carbon fibers. The fiber-reinforced resin sheet according to any one of claims 1 to 6 , wherein the thermoplastic resin is at least one selected from the group consisting of polyolefin, polyamide, polyester, polycarbonate, polystyrene, polyarylene sulfide and polyether ketone. . Adhesives are epoxy resin adhesives, polyester adhesives, rubber adhesives, urethane resin adhesives, acrylic resin adhesives, urea resin adhesives, phenol resin adhesives, melamine resin adhesives, The fiber-reinforced resin sheet according to any one of claims 1 to 7 , which is at least one selected from the group consisting of: It is a method of manufacturing the fiber reinforced resin sheet in any one of Claims 1-8 , Comprising: The manufacturing method of a fiber reinforced resin sheet which has the process of following (I) and (II).
(I) While impregnating the thermoplastic resin on one side in the thickness direction of the nonwoven fabric composed of reinforcing fibers, and on the other side in the thickness direction of the nonwoven fabric, a region where the reinforcing fibers constituting the nonwoven fabric are exposed, Step of forming the reinforcing fiber so that the volume ratio Vfm of the reinforcing fiber in the region is 20% by volume or less (II) Step of impregnating the region in which the reinforcing fiber constituting the nonwoven fabric is exposed with an adhesive A first member comprising the fiber-reinforced resin sheet according to any one of claims 1 to 8 and a second member made of metal are bonded with an adhesive in the fiber-reinforced resin sheet. Integrated molded product. Metal is aluminum, magnesium, iron, copper, is at least one selected from the group consisting of titanium and alloys containing any of them, integrated molded article according to claim 1 0. Automotive interior and exterior, electrical and electronic equipment housing, bicycles, sporting goods for construction materials, aircraft interior materials, or used as a shipping box body according to claim 1 0 or 1 integrated molded according to 1. A method for producing an integrated molded article according to claim 1 0-1 2, to adhere the first member to the second member by means having a pressure and heating, integrated molded Manufacturing method.