JP2016087907A - Method for producing fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fiber-reinforced plastic which has mechanical physical properties applicable to structural materials and isotropy, the temperature dependability of whose mechanical physical properties is lowered, which can be molded in a short time and is hardly warped.SOLUTION: The method for producing the fiber-reinforced plastic, which plastic is prepared by stacking up prepreg base materials, each of which has notches being through-holes so that each of the notches has a crossing with a reinforcing fiber by only one time and an angle formed by intersection of a line segment, which is obtained by connecting a start point of the notch to an end point thereof, with the fiber direction of the reinforcing fiber becomes 30-90°, comprises a step (1) of stacking up two or more pieces of prepreg base materials each having notches to obtain a notched prepreg-stacked base material and a step (2) of heating the notched prepreg-stacked base material to the temperature equal to or higher than the melting point of a matrix resin.SELECTED DRAWING: None

Description

  The present invention is characterized in that it has excellent formability into a complex shape, can be molded in a short time, and has excellent mechanical properties and isotropy in which a molded part can be applied to a structural material. The present invention relates to a method for producing fiber-reinforced plastic. More specifically, at the time of molding, it easily follows a three-dimensional shape such as a rib and a boss, and maintains mechanical properties that can be applied as a structural member. For example, an aircraft member, an automobile member, a wind turbine member for wind power generation, a sports equipment, etc. The present invention relates to a method for producing a fiber reinforced plastic suitably used for the above.

  As a method for molding fiber-reinforced thermoplastics, a base material impregnated with a thermoplastic resin is laminated on continuous reinforcing fibers called prepregs, and shaped into a desired shape by heating and pressing with a press or the like. Stamping is most commonly performed. The fiber reinforced plastic thus obtained has excellent mechanical properties because it uses continuous reinforcing fibers. Moreover, it is possible to design the required mechanical properties by arranging the continuous reinforcing fibers regularly. However, since it is a continuous reinforcing fiber, it is difficult to form a complicated shape such as a three-dimensional shape, and it is mainly limited to members close to a planar shape.

  In order to solve this problem, there is a method for obtaining a sheet having excellent fluidity and excellent stamping formability by dispersing a chip-like prepreg obtained by cutting a tape-like prepreg having a narrow width into a predetermined length on a flat surface. It is disclosed (for example, Patent Document 1). However, it is extremely difficult to dispose a chip-shaped prepreg having a certain width and length on a flat plate in a completely random direction, so that there is a problem that mechanical properties differ depending on the location and orientation even in the same sheet.

  In recent years, D-LFT molding has also been performed in which reinforcing fibers are fed directly into the screw section of a molding machine for the purpose of improving production efficiency, and the fibers are cut and dispersed simultaneously, and then injection molding and extrusion molding are performed continuously. (For example, Non-Patent Document 1). According to this method, since the reinforcing fiber is cut to an appropriate length, it can easily flow and can follow a complicated shape such as a three-dimensional shape. However, D-LFT has a problem in that mechanical properties are deteriorated or a variation in the values is increased because fiber length spots and fiber orientation spots are generated in the cutting and dispersing steps.

  In order to fill the drawbacks of the above materials, by cutting into a prepreg made of continuous fibers and thermoplastic resin, it can be molded in a short time, and exhibits excellent formability at the time of molding. Laminated substrates that are said to exhibit excellent mechanical properties when disclosed (for example, Patent Documents 2 and 3). However, compared with D-LFT, the mechanical properties are high and the variation is small, but it cannot be said that the strength is sufficient for application as a structural material.

  Moreover, the method of improving the above-mentioned intensity | strength and its dispersion | variation by specific cutting shape is shown (for example, patent document 4, 5, 6). However, this method improves mechanical properties and dispersion, but the uniform fluidity to complex three-dimensional shapes such as thin ribs and bosses is insufficient, and the environment is above the physical heat resistance temperature of the matrix resin. There was also a problem that the mechanical properties deteriorated significantly below. Furthermore, Patent Document 5 discloses a manufacturing method for improving strength by charging a laminated base material having a smaller area than the mold during molding and causing the laminated base material to flow during molding. This method is not practical because it causes large fiber orientation spots due to flow, increases variability, and causes large warpage of the molded product.

JP 07-164439 A Japanese Unexamined Patent Publication No. 63-247010 JP-A 63-267523 JP 2008-207544 A JP 2008-207545 A JP 2009-286817 A In-line compounding and molding of long-fiber reinforced thermoplastics (D-LFT): Insight into a rapid growing technology. ANTEC 2004 Conference Processings p. 3500

  The present invention is intended to solve the problems associated with the prior art as described above, and has mechanical properties and isotropic properties applicable to structural materials, and the temperature dependence of the mechanical properties is low. Another object of the present invention is to provide a method for producing a fiber-reinforced plastic that can be molded in a short time and has little warpage because it is excellent in formability to a more complicated shape.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors are composed of reinforced fibers oriented in one direction and a thermoplastic matrix resin, and have a notch at a specific angle with respect to the fiber direction. It has been found that the above problems can be solved by using materials, laminating and heating, and the present invention has been completed. That is, the gist of the present invention resides in the following <1> to <4>.

  <1> A method for producing a fiber reinforced plastic in which two or more prepreg base materials composed of unidirectionally oriented reinforcing fibers and a thermoplastic matrix resin are laminated, wherein the prepreg base material is formed from the front surface to the back surface. Each cut is provided so as to intersect with each reinforcing fiber only once, and a line segment connecting the start point and the end point of the cut intersects with the fiber direction of the reinforcing fiber. A method for producing a fiber-reinforced thermoplastic having an angle of 30 ° or more and 90 ° or less and having the following steps (1) and (2).

(1) Step of laminating two or more prepreg base materials having the incisions to form a notched prepreg laminated base material (2) Step of heating the incised prepreg laminated base material to a melting point or higher of the matrix resin <2> The method for producing a fiber-reinforced plastic according to the above <1>, which has the following step (3) after the step (2).
(3) The heated notched prepreg laminated base material is pressed with a press and spread in a mold, and the projected area is 1.5 times or more to 10 times the area of the notched prepreg laminated base material. <3> The method for producing a fiber-reinforced plastic according to <1> or <2>, wherein the fiber-containing volume ratio of the prepreg base material having the cut is 20 vol% or more and 60 vol% or less.

  <4> The method for producing a fiber-reinforced plastic according to any one of the above <1> to <3>, wherein the laminated configuration of the cut prepreg laminated base material is pseudo-isotropic lamination.

  According to the present invention, while having mechanical properties and isotropic properties applicable to structural materials, the temperature dependence of mechanical properties is low, and further, it is excellent in shaping into complex shapes and can be molded in a short time. It is possible to obtain a method for producing a fiber reinforced plastic that has little warpage.

It is a figure which shows the pigeon channel type rib metal mold | die used in the Example.

  The present invention is a method for producing a fiber reinforced plastic in which two or more prepreg base materials composed of unidirectionally oriented reinforcing fibers and a thermoplastic matrix resin are laminated, wherein the prepreg base material is formed from the surface. It has a notch penetrating through the back surface, each notch is provided so as to intersect with each reinforcing fiber only once, and an intersection between a line segment connecting the start point and the end point of the notch and the fiber direction of the reinforcing fiber This is a method for producing a fiber-reinforced thermoplastic having an angle of 30 ° or more and 90 ° or less and having the following steps (1) and (2).

(1) A step of laminating two or more prepreg base materials having the incisions to form a prepreg laminated base material with cuts (2) A step of heating the prepreg laminated base material with cuts to a melting point or higher of the matrix resin It is preferable to have the following process (3) after the process (2).
(3) The heated notched prepreg laminated base material is pressed with a press and spread in a mold, and the projected area is 1.5 times or more to 10 times the area of the notched prepreg laminated base material. The following steps (prepreg base material with notches)
The prepreg base material used in the present embodiment is a sheet-like prepreg that includes a reinforcing fiber oriented in one direction and a thermoplastic matrix resin, and has a notch penetrating from the front surface to the back surface in a direction crossing the reinforcing fiber. is there. The reinforcing fibers oriented in one direction and the thermoplastic matrix resin will be described later. “Each cut is provided so as to intersect with each reinforcing fiber only once” means that the direction of the linear cut is not parallel to the reinforcing fiber, and is included in the prepreg at the portion intersecting with the cut. That is, the reinforcing fiber is cut.

  The prepreg base material having a notch used in the present invention has an angle θ that forms a reinforcing fiber on the entire surface of the prepreg base material (an angle at which the line segment connecting the start point and the end point of the incision intersects the fiber direction of the reinforcing fiber). ) Must have a cut in the range of 30 ° to 60 °. When the absolute value of θ is extremely small or close to a right angle, when the laminate of the prepreg base material having a cut is spread by heating and pressurization, the fiber orientation becomes uneven, and the isotropic property is low. There is a problem of warping, but if the absolute value of θ is in the range of 30 ° to 60 °, the fiber of the prepreg base material having notches may be spread by heating and pressurizing. There are few orientation spots, isotropic properties, and no warping. In addition to these, when the absolute value of θ is an extremely small angle, the fluidity is lowered. However, if the absolute value of θ is 30 ° or more, it is good for a portion such as a rib or a boss during stamping molding. Three-dimensional fluidity is obtained. In addition, when the absolute value of θ is close to a right angle, fluidity can be secured, but local resin accumulation occurs due to the flow. If the absolute value is 60 ° or less, the occurrence of local resin accumulation due to flow can be suppressed, and the mechanical properties and isotropy of the fiber-reinforced plastic are excellent.

  It is preferable that the fiber length L of the reinforcing fiber divided by the cutting is in the range of 2 mm to 100 mm. When the fiber length L is in the range of 2 mm or more and 100 mm or less, the three-dimensional fluidity to the parts such as ribs and bosses during stamping molding and excellent mechanical properties when used as fiber reinforced plastic can be achieved. From the viewpoint of fluidity, the shorter the fiber length L is, the better. However, by setting the fiber length L to 100 mm or less, good three-dimensional fluidity to parts such as ribs and bosses can be obtained during stamping molding. The fiber length L is preferably longer from the viewpoint of mechanical properties, but by setting it to 2 mm or more, an opportunity physical property applicable to a structural member can be obtained when a fiber reinforced plastic is used. In view of the relationship between fluidity and mechanical properties, the fiber length L is more preferably 15 mm or greater and 55 mm or less.

  The cut length l of the prepreg base material having a cut used in the present invention is preferably in the range of 4 mm to 300 mm. When the cut length l is set to 300 mm or less, when the fiber reinforced plastic is used, the breakage starting from the cut portion can be suppressed, and the mechanical properties are excellent. On the other hand, when the cut length l is extremely short, it is difficult to substantially insert the cut into the prepreg.

  The fiber-containing volume fraction Vf of the prepreg base material having a cut used in the present invention is preferably 20 vol% or more and 60 vol% or less. Since the motive force of fluidity is resin flow, Vf is preferably as low as possible from the viewpoint of fluidity. By setting Vf to 60 vol% or less, good three-dimensional flow to the parts such as ribs and bosses during stamping molding Sex is obtained. From the viewpoint of fluidity, Vf is more preferably 45 vol%. When Vf is extremely low, the mechanical properties required for the structural material cannot be obtained, but by setting Vf to 20 vol% or more, good mechanical properties can be obtained. Moreover, it is more preferable to set Vf to 25 vol% or more, and the opportunity physical property required for a structural material can be obtained. The fiber-containing volume fraction Vf according to the present invention can be measured based on JIS K7075.

  The reinforcing fiber of the prepreg base material used in the present invention is not particularly limited, and examples thereof include inorganic fibers, organic fibers, metal fibers, or fibers having a hybrid configuration in which these are combined. Examples of the inorganic fiber include carbon fiber, graphite fiber, silicon carbide fiber, alumina fiber, tungsten carbide fiber, boron fiber, and glass fiber. Examples of organic fibers include aramid fibers, high density polyethylene fibers, other general nylon fibers, and polyesters. Examples of the metal fibers include fibers such as stainless steel and iron, and may be carbon fibers coated with metal. Among these, in consideration of mechanical properties such as strength of the final molded product, carbon fibers are preferable, and PAN-based carbon fibers are more preferable.

  Moreover, it is necessary to use a thermoplastic resin for the matrix resin of the prepreg base material used in the present invention. That is, in the case of a fiber reinforced plastic using discontinuous reinforcing fibers, a thermoplastic resin generally having a higher toughness value than a thermosetting resin is used as a matrix resin in order to break the fiber ends so as to connect each other. As a result, strength, particularly impact resistance is improved. In addition, since the thermoplastic resin is cooled and solidified without chemical reaction to determine the shape, it can be molded in a short time, and it is excellent in productivity. It can be shaped.

  The thermoplastic resin used in the present invention is not particularly limited. For example, polycarbonate resin, polyester resin, polyamide resin, liquid crystal polymer resin, polyether sulfone resin, polyether ether ketone resin, polyarylate resin, polyphenylene ether resin, polyphenylene Sulfide resin, polyacetal resin, polysulfone resin, polyimide resin, polyolefin resin, polystyrene resin, modified polystyrene resin, ABS resin, modified ABS resin, MBS resin, polymethyl methacrylate resin, and modified resins thereof, and polymer alloy resins thereof Is mentioned. Any one of these may be used alone, or two or more may be used in combination, but a polypropylene resin and / or polyamide resin, or a modified resin of polypropylene resin and / or polyamide resin is preferable. More preferably, it is an acid-modified polypropylene resin from the viewpoint of adhesiveness with reinforcing fibers.

(Preparation method of prepreg base material)
A method for producing a prepreg base material obtained by impregnating a reinforced fiber oriented in one direction with a thermoplastic resin is a method of impregnating a molten resin with an extruder, a method of dispersing and melting a powder resin in a fiber layer, a resin A method of laminating and filming, a method in which a resin is dissolved in a solvent and impregnated in the form of a solution, and then the solvent is volatilized. There is a method of making it into a polymer. The method of impregnating the molten resin with an extruder has the advantage that the resin does not need to be processed, but it is difficult to produce a stable prepreg. The method of dispersing the powder resin in the fiber layer has an advantage that it is easily impregnated, but it is difficult to uniformly disperse the powder in the fiber layer. The method of laminating the resin into a film requires film processing, but tends to produce a relatively good quality. The step of impregnating the thermoplastic resin by the melting method is not only the extruder, but also a method of solidifying the prepreg after melt impregnation by a combination of a heating press and a cooling press, and a heating zone and a cooling zone are provided using a double belt press. There is a way. The method using a double belt press is excellent in productivity because it can be produced continuously.

(Method for producing prepreg base material having notches)
The manufacturing method of the prepreg base material which has a notch used by this invention is not specifically limited, A notch can be inserted in the said prepreg base material by a well-known method. For example, there is a method of making a cut using a laser marker, a cutting plotter, a cutting die or the like.

(1) Step of laminating two or more prepreg base materials having the incision to form a prepreg laminated base material with incision The present invention laminates two or more prepreg base materials having the incision to form a prepreg with incision. It is necessary to have a process of forming a laminated base material. From the viewpoint of high fluidity, a notched prepreg laminated base material in which four or more prepreg base materials having incisions are laminated is preferable, and particularly preferred is a notched prepreg in which eight or more prepreg base materials having incisions are laminated. It is a laminated substrate. In addition, from the viewpoint of production cost, it is usually a prepreg laminate with a cut obtained by laminating 192 or less prepregs having cuts, preferably a prepreg laminate with a cut obtained by laminating 96 or less prepregs having cuts. is there.

  The lamination method in the step of laminating two or more prepreg base materials having the notches of the present invention to form the notched prepreg laminated base materials is not particularly limited, and may be laminated by a known method.

  As a laminated structure, it is preferable to laminate a plurality of sheets so that the reinforcing fibers are oriented in at least two directions. A more preferable laminated structure is one in which four times of 0/45/90 / -45 are symmetrically laminated ([0/45/90 / -45] ns) or three layers of 0/60 / -60. This is a pseudo-isotropic method expressed by symmetrically stacking n repetitions ([0/60 / -60] ns). By having fiber orientations in two or more directions, warping of the fiber-reinforced plastic can be suppressed. Furthermore, with regard to fluidity, since the flow of the resin in the 90 ° direction of the reinforcing fiber is the driving force for moving the reinforcing fiber, the flow of the fiber differs depending on the fiber orientation of the adjacent prepreg at the time of lamination, but the fiber orientation is simulated, etc. In this way, the fluidity becomes isotropic, and a fiber-reinforced plastic having excellent fluidity with little variation in fluidity can be obtained.

  In order to prepare the cut prepreg laminated base material as needed, a part or the whole of the layers of the cut prepreg laminated base material may be welded by ultrasonic waves or heating.

(2) Step of heating the notched prepreg laminated base material to the melting point of the matrix resin or higher The present invention is the melting point of the matrix resin constituting the prepreg of the notched prepreg laminated base material obtained in (1) above. It is necessary to have the process of heating above. By this step, the laminated base material can be integrated.

  The heating method in the step of heating the notched prepreg laminated substrate of the present invention is not particularly limited, and may be heated by a known method, and the method of heating in an IR heater or a circulating hot air oven is raised. . In addition, the above-mentioned (preheated notched prepreg laminated base material is pressed and spread with a press machine in a mold, and the projected area is 1.5 times or more the area of the notched prepreg laminated base material. The prepreg laminated base material with cuts may be put into a mold used for the step of 10 times or less, and then heated by a heating press.

  The heating temperature is not particularly limited as long as it is equal to or higher than the melting point of the matrix resin, but it is preferable to heat at a temperature 15 to 60 ° C. higher than the melting point of the matrix resin.

(3) Pressurize the heated pre-cut laminated prepreg substrate with a press and spread it in the mold, and project the projected area from 1.5 times to 10 times the area of the cut prepreg laminated substrate. The present invention has a step of heating and pressurizing the notched prepreg laminated substrate to spread it, and setting the projected area to be 1.5 times to 10 times the area of the notched prepreg laminated substrate. There is a need. By pressing the cut prepreg laminated substrate in the mold with a press machine, the projected area is expanded to more than 1.5 times the area of the cut prepreg laminated substrate, so that the fiber is in all directions. It is possible to obtain a fiber reinforced plastic that is oriented, has low anisotropy, increases dispersibility of the reinforcing fibers and the matrix resin in the thickness direction, has excellent mechanical properties, and has low temperature dependency. On the other hand, when the laminated base material is extremely spread, there is a problem that fluidity at the time of stamping molding is lowered due to entanglement of fibers, but the notched prepreg laminated base material is heated and pressurized to be spread. If the projected area at that time is 10 times or less the area of the cut prepreg laminated base material, good fluidity can be ensured during stamping molding.

  The temperature at the time of pressurization is preferably in the range of −60 ° C. to + 60 ° C. with respect to the melting point temperature of the matrix resin.

  The pressure applied to the cut prepreg laminated base material in the pressurization is preferably 0.1 to 30 MPa, more preferably 0.2 to 10 MPa.

  The heating and pressurizing time is preferably 0.1 to 30 minutes, more preferably 0.5 to 10 minutes. Moreover, it is preferable that the cooling time provided after a heating and pressurization is 0.5 to 30 minutes.

  Next, the present invention will be described more specifically with reference to examples. The present invention is not limited to the invention described in the examples. The raw materials, fiber reinforced plastic manufacturing methods, and physical property evaluation methods used in the following examples are shown.

<Raw material>
Carbon fiber: Pyrofil TR 50S15L AD manufactured by Mitsubishi Rayon Co., Ltd.
Acid-modified polypropylene resin: Modic P958 manufactured by Mitsubishi Chemical Corporation
<Physical property evaluation>
(warp)
Place the obtained 300 mm square plate-like fiber reinforced plastic on a horizontal plane, measure the height of the fiber reinforced plastic from the four horizontal corners, and if the sum of the height from the four horizontal planes is less than 4 mm, From the above, it was recorded as Δ if it was less than 6 mm and x if it was 6 mm or more. The results are shown in Tables 1-4.

(Evaluation of bending test properties)
From the obtained 300 mm square flat fiber reinforced plastic, 4 pieces each in 4 directions of 0 °, 45 °, 90 ° and 135 °, a total of 16 pieces, a bending strength test piece having a length of 100 mm and a width of 25 mm. Cut out. The cut-out bending test piece was subjected to a three-point bending test at a crosshead speed of 5.0 mm / min under a room temperature environment in accordance with a test method specified in JIS K-7074. The rate was measured. As a testing machine, an Instron universal testing machine 4465 type was used. The average value of n = 16 of each of the obtained measured values was recorded as the bending strength and the bending elastic modulus, and the bending strength was obtained by dividing the standard deviation by the average value and multiplying it by 100. V. Recorded as. The results are shown in Tables 1-4. Note that C.I. V. The smaller the value, the higher the isotropic property.

(Bending elastic modulus at high temperature)
From the obtained 300 mm square flat fiber reinforced plastic, 4 pieces each in 4 directions of 0 °, 45 °, 90 ° and 135 °, a total of 16 pieces, a bending strength test piece having a length of 100 mm and a width of 25 mm. Cut out. The cut bending test piece was subjected to a three-point bending test at a crosshead speed of 5.0 mm / min with a distance between the gauge points of 80 mm in accordance with the test method specified in JIS K-7074 except that the test environment temperature was 80 ° C. The elastic modulus was measured. As a testing machine, an Instron universal testing machine 4465 type was used. The average value of n = 16 of the obtained measured values was defined as the flexural modulus at 80 ° C. When the flexural modulus at 80 ° C. was 95% or more of the flexural modulus at room temperature, it was recorded as “◯”, from 90% to less than 95%, “Δ”, and when less than 90%, “x”. The results are shown in Tables 1-4.

(Evaluation of tensile strength)
From the obtained 300 mm square plate-like fiber reinforced plastic, according to the test method specified in JIS K-7074 in the 0 ° direction, emery abrasive paper # 400 manufactured by Koyo Co., Ltd. was used as the tab material, and Aron Alpha manufactured by Toa Gosei Co. Six type 3 tensile test pieces were prepared using GEL-10. A tensile test was performed at a distance between the gauge points of 50 mm and a crosshead speed of 1.0 mm / min to measure the tension strength. As a testing machine, an Instron universal testing machine 5882 type was used. The average value of n = 6 of the measured values obtained was recorded as the tensile strength. The results are shown in Tables 1-4.

(Evaluation of liquidity)
Four 300 mm × 50 mm plate-like objects were cut out from the obtained 300 mm square flat fiber-reinforced plastic. It was heated for 3 minutes at 280 ° C. using an infrared heater (manufactured by NGK, product name: QU-95469-S01) and placed in a pigeon channel rib mold (FIG. 1) set at 130 ° C. Then, using a 100 t press (manufactured by Yamamoto Iron Works, press molding machine PPM1-100), pressing was performed at 90 t for 3 minutes. The state of filling into the ribs was confirmed visually, and recorded as ◯ if the filling rate was 98% or more, Δ if it was 85% or more and less than 98%, and x if it was less than 85%. The results are shown in Tables 1-4.

Example 1
A fiber sheet with a basis weight of 72 g / m ² is formed by aligning raw carbon fibers in one direction in a flat shape, and a film with a basis weight of 36 g / m ^{2 made} of the raw acid-modified polypropylene resin is sandwiched from both sides of the fiber sheet. The resin sheet was impregnated into the fiber sheet by heating and pressurizing a plurality of calender rolls to prepare a prepreg base material having a fiber volume content Vf of 33 vol% and a thickness of 0.12 mm.

  Using a cutting plotter (product name: L-2500, manufactured by Rezac Co., Ltd.), this prepreg base material has an angle θ of 45 °, the fiber length L of the reinforcing fiber is 25 mm, and the cut length l is 42 mm. A cut was made so that the prepreg substrate was cut into 212 mm squares.

  The prepreg base material having this cut has a laminated structure of [0/45/90 / −45] ns with a repetition count n = 4, and the cut direction is [−45/0/45/90] ns. The four corners were spot welded using an ultrasonic welding machine 2000LPt manufactured by Nippon Emerson Co., Ltd. to obtain a prepreg laminated base material with cuts.

  The thus obtained notched prepreg laminated base material was placed in a 300 mm square and 1.5 mm deep stamping mold, heated to 200 ° C., and then subjected to a multistage press (compression molding machine manufactured by Shinto Metal Industry, Product name: SFA-50HH0), heated and pressurized at a pressure of 0.55 MPa for 7 minutes on a 220 ° C. surface, cooled to room temperature at the same pressure, and the projected area was 2 of the area of the prepreg laminated substrate with slits. A doubled fiber reinforced plastic was obtained. The physical properties of the obtained fiber reinforced plastic were evaluated.

(Examples 2 and 3, Comparative Examples 1 and 2)
The same operation as in Example 1 was performed except that the cutting angle θ was changed as shown in Table 1. The results are shown in Table 1.

(Examples 4, 5, 6, 7 and Comparative Examples 3 and 4)
Other than changing the cut size of the prepreg base material having a cut and the number of repetitions n of the laminated structure and changing the multiple of the projected area of the fiber reinforced plastic to the area of the cut prepreg laminated base material as shown in Table Was carried out in the same manner as in Example 2. The results are shown in Table 2. In Comparative Example 4, only warpage and fluidity were evaluated.

(Example 8)
The same procedure as in Example 6 was performed except that the laminated structure was changed as shown in Table 3. The results are shown in Table 3. The tensile strength was not evaluated.

(Comparative Example 5)
Other than changing the cut size of the prepreg base material having a cut and the number of repetitions n of the laminated structure and changing the multiple of the projected area of the fiber reinforced plastic to the area of the prepreg laminated base material with the cut as shown in Table 2. Was carried out in the same manner as in Example 8. The results are shown in Table 3. The tensile strength was not evaluated.

Example 9
The same procedure as in Example 2 was performed except that the basis weight of the carbon fiber was 108 g / m ² , the basis weight of the acid-modified polypropylene resin film was 27 g / m ² , and a prepreg base material having a fiber volume content Vf of 50 vol% was used. The results are shown in Table 4.

1: Top surface 2: Rib

Claims (4)

A method for producing a fiber reinforced plastic in which two or more prepreg base materials composed of unidirectionally oriented reinforcing fibers and a thermoplastic matrix resin are laminated, the prepreg base material penetrating from the front surface to the back surface. Each notch is provided so as to intersect with each reinforcing fiber only once, and an angle between the line segment connecting the start point and the end point of the notch and the fiber direction of the reinforcing fiber is 30. The manufacturing method of the fiber reinforced thermoplastic which is (degree) and 90 degrees or less and has the process of following (1) and (2).
(1) A step of laminating two or more prepreg base materials having the incision to form a prepreg laminated base material with notches (2) A step of heating the incised prepreg laminated base material to a melting point or higher of the matrix resin The manufacturing method of the fiber reinforced plastics of Claim 1 which has the process of following (3) after the process of (2).
(3) The heated notched prepreg laminated base material is pressed with a press and spread in a mold, and the projected area is 1.5 times or more to 10 times the area of the notched prepreg laminated base material. The following process   The method for producing a fiber-reinforced plastic according to claim 1 or 2, wherein a fiber-containing volume ratio of the prepreg base material having the cut is 20 vol% or more and 60 vol% or less.   The method for producing a fiber-reinforced plastic according to any one of claims 1 to 3, wherein the laminated structure of the prepreg laminated substrate with cuts is pseudo isotropic lamination.