JP2020082661A - Laminated base material, intermediate product and molded product - Google Patents

Abstract

To provide a laminated base material for eliminating an excess part generated at an end part of a pre-preg when shaping the pre-preg.SOLUTION: A laminated base material, containing at least pre-preg tapes which are made of a unidirectional reinforced fiber impregnated with a matrix resin and whose width is 2.5-40 mm, is used. A first unit is formed with the pre-preg tapes parallelly arranged at equal intervals. Then, a shift angle is determined based on a number of lamination axes. Then, a second unit is formed with pre-preg tapes inclined at an angle shifted by the determined shift angle from that of the lamination axes of the first unit and arranged at the equal intervals. Further, a third unit is formed with pre-preg tapes inclined at an angle shifted by the determined shift angle from that of the lamination axes of the second unit. Similarly, the above-mentioned steps are repeated a predetermined number of times, to provide the laminated base material in which the pre-preg tapes are laminated.SELECTED DRAWING: Figure 1-12

Description

The present invention relates to a laminated base material in which a prepreg tape obtained by impregnating a unidirectional reinforcing fiber with a matrix resin is laminated.

Reinforcing fiber prepregs that use carbon fibers, aramid fibers, glass fibers, etc. as reinforcing fibers are used as structural materials for aircraft and automobiles, sports equipment, and materials for general industrial applications by taking advantage of their high specific strength and specific elastic modulus. Has been done. In particular, it is widely used in the aviation industry for the purpose of saving fuel and reducing operating costs.

Since prepreg made by impregnating unidirectional reinforcing fibers with matrix resin is a material that is difficult to form into a three-dimensional shape, the prepreg should be slit to a width of a few mm to form a tape, and then lined up in a three-dimensional shape and stacked. There is. As a laminating method, a technique called auto tape layup is used, in which a tape having a narrow width is simply allowed to follow a substantially two-dimensional shape and the shape can be followed even in a complicated shape. However, there is a problem in that productivity is low when stacking a large area and a three-dimensional shape of a thick member.

On the other hand, as a process with excellent productivity, hot forming is known in which a prepreg laminated on a flat plate is immediately formed into a three-dimensional shape. However, there has been a problem that wrinkles and bridging (fiber tension) occur due to the insufficient deformability of the prepreg during shaping, and the yield of the fiber-reinforced plastic decreases. Specifically, at a portion where the shape changes, for example, a bent portion, a difference in peripheral length occurs above and below the prepreg laminate. Although the thickness of the prepreg laminate is reduced due to heat shrinkage of the matrix resin impregnated in the prepreg during the process of solidification into fiber-reinforced plastic, the prepreg laminate has continuous stretch fibers with low elongation In order to eliminate the difference, the reinforcing fiber itself buckles to cause wrinkles or bridging, which causes a molding defect of the fiber-reinforced plastic. Further, since it is difficult to apply the molding pressure to the portion immediately below where the bridging occurs, there is a demerit that voids are likely to occur. This void generation was a more remarkable problem in low pressure molding such as oven molding using a vacuum pump as a pressurizing means.

As a technique for reducing wrinkles during forming, a method is known in which buckling is reduced by continuously applying a compressive force in the out-of-plane direction of a prepreg laminated on a flat plate (for example, Patent Document 1). In the technique disclosed in Patent Document 1, a tensile material is placed on the laminated prepregs and the tension is continuously maintained from the outer edge, so that a compressive force is continuously applied in the out-of-plane direction of the prepregs laminated on the flat plate to cause buckling. Can be reduced.

Further, as a technique for improving the shapeability to a three-dimensional shape, by using a prepreg having a woven structure, it is possible to reduce wrinkles by increasing the in-plane deformability by utilizing the bending of fibers and the eye part of the woven fabric. The method is known. In particular, in aircraft parts, woven prepregs are used in portions where in-plane deformability is required.

Japanese Patent Publication No. 2016-514634

However, the method of reducing wrinkles during forming disclosed in Patent Document 1 has a problem in that it is not possible to eliminate an excess portion generated when a prepreg is shaped. Further, the prepreg having a woven structure has a problem that the cost of the weaving process is high.

Then, the subject of this invention is providing the laminated base material which can reduce generation|occurrence|production of a wrinkle, without generating an excessive part at the time of shaping of a prepreg.

In order to achieve the above object, the laminated base material of the present invention employs the following configurations. That is,
(1) A laminated base material including at least a prepreg tape in which unidirectional reinforcing fibers are impregnated with a matrix resin, and a width of the prepreg tape orthogonal to a fiber orientation direction has a constant width of 2.5 mm or more and 40 mm or less. A laminated base material in which the prepreg tape is arranged so as to have the following configuration.
[1] An individual unit in which a plurality of prepreg tapes (width: a (mm)) are arranged in parallel at equal intervals with the individual clearances shown by the following formulas being formed. The fiber orientation direction of the prepreg tape is called a lamination axis.
Individual clearance = a x d + (1 + d) x b (mm)
Here, b (mm) is a distance (−a/2 mm≦b≦5 mm) between the prepreg tapes which are adjacent to each other in the laminating axis in the same direction in the completed form of the laminated base material. In addition, the minus display of the distance indicates a state in which the prepreg tapes are overlapped and laminated. Further, d is the total number of steps until the completion of the laminated base material described later.
[2] A new individual unit is arranged on the arranged individual unit. At this time, the inclination of the stacking axis of the newly arranged individual unit is displaced from the inclination of the stacking axis of the immediately preceding individual unit by a shift angle of the individual unit stacking axis defined below.
Shift angle of individual unit stacking axis = 180/e
Note that e is the number of laminated axes included in the aggregate of individual units.
This is repeated until just before the first individual unit has the same stacking axis direction. The number of repetitions is called the number of loops. The placement process of [1] and [2] is collectively referred to as one step.
[3] Arrange the individual unit for the second step. The stacking axis direction of the first individual unit in the second step is the same stacking axis direction as the first individual unit arranged in the first step, and is represented by the following formula for the prepreg tape constituting the first step individual unit. It is arranged by shifting the parallel movement distance.
Translation distance: a+b
Hereinafter, similar to the description in [2], a new individual unit is arranged by shifting the angle of the stacking axis, and all the individual units forming the second step are arranged.
[4] The arrangement of individual units is repeated until the number of steps reaches d.
(2) The laminated base material according to (1), wherein the fiber orientation directions are three or more directions.
(3) An intermediate obtained by shaping the laminated base material according to (1) or (2).
(4) A molded product obtained by molding the laminated base material described in (1) or (2) or the intermediate body described in (3).
Is.

ADVANTAGE OF THE INVENTION According to this invention, the laminated base material which eliminates the surplus part which generate|occur|produces at the edge part of a prepreg at the time of shaping a prepreg can be provided.

FIG. 3 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, in which the number of axes of the laminated base material is e=3, and the total number of steps until the completion of the laminated base material is d=4. In the completed form of the laminated base material, the distance b between prepreg tapes adjacent to each other in the laminating axis in the same direction is b=0.5 mm, and the individual unit 3 (the number of steps is 1, the number of loops is 1) is arranged. .. FIG. 4 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (the number of steps is 1 and the number of loops is 2) are arranged. FIG. 6 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (step number 1, loop number 3) are arranged. FIG. 4 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (two steps, one loop) are arranged. FIG. 4 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (two steps and two loops) are arranged. FIG. 4 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (two steps, three loops) are arranged. FIG. 6 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (three steps, one loop) are arranged. FIG. 6 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (three steps, two loops) are arranged. FIG. 3 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (3 steps, 3 loops) are arranged. FIG. 3 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (the number of steps is 4, the number of loops is 1) are arranged. FIG. 3 is a schematic view of a process for obtaining a laminated base material according to an embodiment of the present invention, showing a state in which individual units 3 (the number of steps is 4, the number of loops is 2) are arranged. It is a schematic diagram of a layered substrate concerning one embodiment of the present invention, and shows the state where individual units 3 (the number of steps 4 and the number of loops 3) are arranged. FIG. 3 is a schematic view of a laminated base material according to an embodiment of the present invention, in which the number of axes e=4, the total number of steps until completion of the laminated base material d=8, and the same direction in the completed form of the laminated base material. The laminated base material in which the distance b between prepreg tapes adjacent to each other on the laminating axis=tape half width is illustrated. FIG. 3 is a schematic view of a laminated base material according to an embodiment of the present invention, in which the number of axes e=5, the total number of steps until completion of the laminated base material d=4, and the same direction in the completed form of the laminated base material. The laminated base material in which the distance b between adjacent prepreg tapes on the laminating axis is 0.5 mm is illustrated.

Preferred embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples of preferred embodiments of the present invention, and the present invention is not limited to these embodiments.

The present invention is a laminated base material including at least a prepreg tape in which unidirectional reinforcing fibers are impregnated with a matrix resin, and the width of the prepreg tape orthogonal to the fiber orientation direction has a constant width of 2.5 mm or more and 40 mm or less. The prepreg tape is arranged so as to have the following structure.
[1] An individual unit in which a plurality of prepreg tapes (width: a (mm)) are arranged in parallel at equal intervals with the individual clearances shown by the following formulas being formed. The fiber orientation direction of the prepreg tape is called a lamination axis.
Individual clearance = a x d + (1 + d) x b (mm)
Here, b (mm) is a distance (−a/2 mm≦b≦5 mm) between the prepreg tapes which are adjacent to each other in the laminating axis in the same direction in the completed form of the laminated base material. In addition, the minus display of the distance indicates a state in which the prepreg tapes are overlapped and laminated. Further, d is the total number of steps until the completion of the laminated base material described later.
[2] A new individual unit is arranged on the arranged individual unit. At this time, the inclination of the stacking axis of the newly arranged individual unit is displaced from the inclination of the stacking axis of the immediately preceding individual unit by a shift angle of the individual unit stacking axis defined below.
Shift angle of individual unit stacking axis = 180/e
Note that e is the number of laminated axes included in the aggregate of individual units.
This is repeated until just before the first individual unit has the same stacking axis direction. The number of repetitions is called the number of loops.
The placement process of [1] and [2] is collectively referred to as one step.
[3] Arrange the individual unit for the second step. The stacking axis direction of the first individual unit in the second step is the same stacking axis direction as the first individual unit arranged in the first step, and is represented by the following formula for the prepreg tape constituting the first step individual unit. It is arranged by shifting the parallel movement distance.
Translation distance: a+b
Hereinafter, similar to the description in [2], a new individual unit is arranged by shifting the angle of the stacking axis, and all the individual units forming the second step are arranged.
[4] The arrangement of individual units is repeated until the number of steps reaches d.

An example of the laminated base material is shown in FIGS. The laminated base materials illustrated in FIGS. 1 to 12 are adjacent to each other with the number of axes e=3, the total number of steps until completion of the laminated base material d=4, and the laminated axes in the same direction in the completed form of the laminated base material. The distance between the prepreg tapes is set to b=0.5 mm.

The prepreg tape 1 is composed of unidirectional reinforcing fibers and matrix resin. As the reinforcing fiber, it is preferable to use, for example, carbon fiber, glass fiber, aramid fiber, Kevlar fiber, or the like. Examples of the matrix resin include a thermosetting resin and a thermoplastic resin. An epoxy resin or the like can be used as the thermosetting resin. As the thermoplastic resin, for example, nylon resin, PPS (polyphenylene sulfide) resin, PEEK (polyether ether ketone) resin, or the like can be used. The width: a (mm) of the prepreg tape is 2.5 mm or more, and it is important that it is 40 mm or less. If the width: a (mm) of the prepreg is less than 2.5 mm, the amount that can be laminated at one time is small, which is not economical. When the width of the prepreg: a (mm) exceeds 40 mm, when the prepreg is to be arranged on a curved line, the curvature that can be arranged is limited due to the difference in the circumferential length of the tape, and the degree of freedom of arrangement becomes small.

Next, a specific arrangement means of the prepreg tape will be described in order.
[1] An individual unit in which a plurality of prepreg tapes (width: a (mm)) are arranged in parallel at equal intervals with the individual clearances shown by the following formulas being formed. The fiber orientation direction of the prepreg tape is called a lamination axis.
Individual clearance = a x d + (1 + d) x b (mm)

Here, b (mm) is a distance (−a/2 mm≦b≦5 mm) between the prepreg tapes which are adjacent to each other in the laminating axis in the same direction in the completed form of the laminated base material. In addition, the minus display of the distance indicates a state in which the prepreg tapes are overlapped and laminated. Further, d is the total number of steps until the completion of the laminated base material described later.

If the value of the total number d of steps is increased, the number of prepreg tapes that traverse in the thickness direction increases, so that the interlayer strength is expected to increase, but the number of steps increases, so the lamination time increases. It is desirable to determine the value of d according to the intended product physical properties and process properties.

The state where one individual unit is formed is shown in FIG. In the individual unit 3 (the number of steps is 1 and the number of loops is 1) shown in FIG. 1-1, a plurality of prepreg tapes 1 (width: a (mm)) are arranged in parallel at equal intervals with an individual clearance 5 shown by the following formula. It was done. The arrow in the left-right direction shown in the lower part of FIG.

The individual clearance is shown by the following formula.
Individual clearance = a x d + (1 + d) x b (mm)

Here, b (mm) is a distance (−a/2 mm≦b≦5 mm) between the prepreg tapes which are adjacent to each other in the laminating axis in the same direction in the completed form of the laminated base material. When the value of b is increased, there is more room for the prepreg tape to move during shaping, so that the shaping property is improved but the physical properties are reduced. When the value of b is decreased, the physical properties are improved, but the shapeability is decreased. It is desirable to determine the value of b according to the intended product shape and physical properties. If b exceeds 5 mm, the physical properties may be significantly reduced.

If the value of b is less than 0, the prepreg tapes will overlap. When this overlap increases, the number of prepreg tapes laminated at one time increases, so that the lamination time decreases but the physical properties decrease. If b is less than -a/2 mm, the physical properties may be significantly deteriorated.

A procedure for arranging a new individual unit 3 on the individual unit 3 that has been arranged is shown in FIG. 1-2 as an example.

In FIG. 1-2, a new individual unit 3 is placed on the individual unit 3 that has been placed. At this time, the inclination of the stacking axis 4 of the newly arranged individual unit is displaced from the inclination of the stacking axis 4 of the immediately preceding individual unit by a shift angle of the individual unit stacking axis defined below.
Shift angle of individual unit stacking axis = 180/e

Note that e is the number of laminated axes included in the aggregate of individual units.

These operations are repeated until just before the first individual unit has the same stacking axis direction (FIGS. 1-1, 1-2, and 1-3). The number of repetitions is called the number of loops.

The axial direction of the first layer of the stacking axis 4 can be defined as the same direction as the x axis of the xy plane. Further, the angular intervals of the shift angles of the individual unit stacking axes are equal intervals. Regarding the operation of changing the inclination of the stacking axis each time the loop described below is advanced, the rotation direction can be clockwise or counterclockwise.

The number e of stacked axes included in the aggregate of the individual units is three axes in the figure, but is preferably two or more axes. If the number of axes is increased, the physical properties of the material will be more isotropic, but if the number of axes is more than 10, the lamination time will increase and there is a risk of being uneconomical. It is preferably 8 axes or less, more preferably 6 axes or less.

The loop is a procedure in steps, and when the individual unit 3 in which the stacking axis 4 is changed is arranged as shown in FIG. 1-2, its value is one. The individual unit 3 can be described as an individual unit 3 (the number of steps and the number of loops) according to the value of the procedure. For example, FIG. 1-1 shows the arrangement of the individual units 3 (the number of steps is 1, the number of loops 1), and FIG. 1-2 shows the arrangement of the individual units 3 (the number of steps is 1, the number of loops 2). The upper limit of the number of loops is e, where e is the total number of stacking axes, and the value of the number of steps advances by 1 and the value of the number of loops returns to 1 when proceeding to the procedure following e. For example, FIGS. 1-3 show the individual unit 3 (step number 1, loop number 3), and FIGS. 1-4 show the individual unit 3 (step number 2, loop number 1).

Then, the individual unit for the second step is arranged. A step is a stacking procedure, and when the loop completes one cycle, the value of the step advances by one. As shown in the comparison between FIG. 1-1 (step 1, loop 1) and FIG. 1-4 (step 2, loop 1), the stacking axial direction of the first individual unit in the second step is the first in the first step. It is arranged in the same stacking axis direction as the arranged individual units, and is displaced by the parallel movement distance shown by the following formula with respect to the prepreg tape constituting the first unit of the individual units.
Translation distance: a+b

Similarly, as shown in FIG. 1-4, FIG. 1-5, and FIG. 1-6, by displacing the angle of the stacking axis 4 and disposing a new individual unit, all the individual units constituting the second step are arranged. Place the unit.

Subsequently, the arrangement of the individual units is repeated until the number of steps reaches d, as illustrated in FIGS. 1-7 to 1-12.

The number of steps d must be 2 or more and 10 or less. In the case of 1, the base material is not established, and in the case of more than 10, there is a possibility that the lamination time increases and it becomes uneconomical. The number of steps d is preferably 8 or less, more preferably 6 or less. As shown in FIG. 1-12, the number of the prepreg tapes constituting the repeating unit 7 is four for each lamination axis 4. The number of prepreg tapes forming the repeating unit 7 is defined as d, and may be a natural number of 2 or more.

FIG. 2 is an example of a laminated base material according to an embodiment of the present invention, which is defined by the number of axes=4, the repeating unit=8, the wrap length=the tape half width, and the gap length=0. FIG.

FIG. 3 is an example of a laminated base material according to an embodiment of the present invention, and is a laminated base defined by the number of axes=5, the repeating unit=4, the lap length=0, and the gap length=0.5 mm. The lamination mode of the material is shown.

The laminated base material can be shaped and used as an intermediate. Further, after the laminated base material is shaped into the shape of the shaped body by the shaping step or the like, the shaped body can be obtained by the shaping step such as autoclave. Further, a molded body can be obtained by directly subjecting the above-mentioned intermediate body to a molding process such as an autoclave.

The reinforcing fiber multiaxial substrate according to the present invention that eliminates geometrically generated fiber surplus facilitates the shaping process and can be applied to the aircraft industry and the automobile industry.

1 prepreg tape 2 width of prepreg tape 3 individual unit 4 stacking axis 5 individual clearance 6 parallel movement distance 7 repeating unit 8 two adjacent prepreg tapes 9 prepreg tape 10 placed across two adjacent prepreg tapes 10 adjacent two A part where the prepreg tape placed across two prepreg tapes is vertically sandwiched between two adjacent prepreg tapes.

Claims (4)

A laminated base material including at least a prepreg tape in which unidirectional reinforcing fibers are impregnated with a matrix resin, wherein a width of the prepreg tape orthogonal to a fiber orientation direction has a constant width of 2.5 mm or more and 40 mm or less. A laminated base material, wherein the prepreg tape is arranged so as to have a constitution.
[1] An individual unit in which a plurality of prepreg tapes (width: a (mm)) are arranged in parallel at equal intervals with the individual clearances shown by the following formulas being formed. The fiber orientation direction of the prepreg tape is called a lamination axis.
Individual clearance = a x d + (1 + d) x b (mm)
Here, b (mm) is a distance (−a/2 mm≦b≦5 mm) between the prepreg tapes which are adjacent to each other in the laminating axis in the same direction in the completed form of the laminated base material. In addition, the minus display of the distance indicates a state in which the prepreg tapes are overlapped and laminated. Further, d is the total number of steps until the completion of the laminated base material described later.
[2] A new individual unit is arranged on the arranged individual unit. At this time, the inclination of the stacking axis of the newly arranged individual unit is displaced from the inclination of the stacking axis of the immediately preceding individual unit by a shift angle of the individual unit stacking axis defined below.
Shift angle of individual unit stacking axis = 180/e
Note that e is the number of laminated axes included in the aggregate of individual units.
This is repeated until just before the first individual unit has the same stacking axis direction. The number of repetitions is called the number of loops. The placement process of [1] and [2] is collectively referred to as one step.
[3] Arrange the individual unit for the second step. The stacking axis direction of the first individual unit in the second step is the same stacking axis direction as the first individual unit arranged in the first step, and is represented by the following formula for the prepreg tape constituting the first step individual unit. It is arranged by shifting the parallel movement distance.
Translation distance: a+b
Hereinafter, similar to the description in [2], a new individual unit is arranged by shifting the angle of the stacking axis, and all the individual units forming the second step are arranged.
[4] The arrangement of individual units is repeated until the number of steps reaches d. The laminated base material according to claim 1, wherein the fiber orientation directions are three or more directions. An intermediate obtained by shaping the laminated base material according to claim 1 or 2. A molded body obtained by molding the laminated base material according to claim 1 or 2, or the intermediate body according to claim 3.