JP6310578B2 - Pre-preg capable of deep drawing and manufacturing method thereof - Google Patents

Description

The present invention relates to a prepreg sheet of continuous reinforcing fibers impregnated with a resin, a method for producing the same, and a composite material using the prepreg sheet.
More specifically, one or more prepreg sheets made of continuous reinforcing fibers can be laminated, softened by heating and deformed along a three-dimensional curved surface by applying pressure, and fiber continuity is maintained after deformation. In addition, the fiber content in the prepreg sheet can be approximately 60% of the fiber content equivalent to the prepreg sheet obtained by impregnating the resin with the long fibers generally aligned in one direction. , A molded body and a production method thereof.

In general, a fiber reinforced resin composite material structure manufactured using a reinforced fiber and a resin is manufactured using a prepreg sheet that is an intermediate material in which a reinforced fiber is impregnated with a resin. The reason for this is that the prepreg sheet resin is soft and the appropriate number of sheets that match the fiber direction of the appropriate sheet is laminated and molded along a three-dimensional curved mold, and then the resin is solidified to provide rigidity. This is because a composite material structure having a three-dimensional curved surface shape satisfying the required properties such as strength and the like can be obtained.
In molding, in order to avoid the trouble of impregnating the fiber with a resin having a relatively high viscosity after arranging the fibers along the molding direction, the fibers are aligned in advance, and the prepreg impregnated with the resin is formed. Because it is suitable

There are unidirectional resin prepreg sheets, woven prepreg sheets, and short fiber prepregs depending on how to arrange the fibers contained in the prepreg sheet, but the unidirectional resin prepreg sheet is unidirectional with a number of fiber bundles (fiber strands) in parallel. And is impregnated with resin to produce a sheet. A plurality of the unidirectional prepreg sheets are laminated while changing their fiber directions, heated to melt the resin, and then pressurized to produce a composite material. By aligning in one direction, the three-dimensional intersection of fibers can be reduced and the fiber spacing can be narrowed, so that a prepreg sheet having a high contained fiber volume per unit volume can be obtained. Commercial unidirectional prepreg sheets are manufactured with a fiber volume content of around 65%.
By laminating a plurality of prepreg sheets having different fiber directions, it is possible to cope with in-plane multiaxial stress generated in the composite material.
A planar prepreg sheet in which fibers are aligned in one direction hardly stretches and is difficult to be molded along a three-dimensional curved surface. In order to laminate along the three-dimensional shape, cut the planar unidirectional prepreg sheet into small pieces, and laminate them one by one along the curved surface of the three-dimensional shape with the appropriate fiber direction, and solidify the resin Since molding is performed, the molding time becomes longer and the cost also increases.

Fabric prepreg sheets manufactured by impregnating resin into woven fibers are also difficult to stack along a three-dimensional curved surface, as with unidirectional prepreg sheets. Cut prepreg sheets into small pieces one by one Laminate and solidify to produce a composite material. In addition to fabrics that intersect 90 degrees, fabrics such as triaxial fabrics that have fibers intersected in multiple axes are manufactured, but there are similar difficulties in manufacturing composite materials having a three-dimensional curved surface. .
The stretched fiber resists the in-plane elongation of the sheet necessary for the plane to deform into a three-dimensional shape, and the in-plane shear deformation is hindered by the resistance at the fiber intersection.

Short fiber prepregs are cut into long fibers and arranged in a planar shape. However, in a prepreg sheet impregnated with resin, the actual cutting is composed of a large number of single fibers such as 1000, 3000, 6000, etc. Since the fiber strands (bundles) are cut, the transmission of force in the fiber direction between the cut fiber bundles is insufficient, and it is difficult to fully utilize the tensile strength of the fibers. Even in the case of a prepreg having cut-strands arranged in an arbitrary direction on a plane and having characteristics close to in-plane isotropic properties, the average fiber volume content is lowered due to the overlap of strands and the accumulation of resin near the strand cut surfaces. However, the strength and rigidity of the fiber cannot be fully utilized due to the much larger resin pool than the single fiber cross section.
Since the cross-sectional area of the strand increases in the short fiber strand state, the fiber axis when changing the plane to a three-dimensional curved surface with a short fiber length by dispersing the short cut fiber strands into single fibers and dispersing them in the plane There is a dispersion of fibers by a method such as a paper-making method in which the elongation in the direction is replaced with the tensile strain in the fiber direction by axial sliding with other single fibers. However, if the cut single fiber length and the single fiber cross-sectional area ratio are large, the fibers form an entangled curve, and the distortion in the fiber direction (fiber movement) necessary for deformation into a three-dimensional shape of the plane is hindered by the entanglement. Further, it becomes difficult to change to a three-dimensional curved surface, and the fiber content per volume decreases due to the cross overlap of the fibers. (Patent Document 1: JP 2014-28510 A)
If the cut carbon fiber length is shortened to about several times the single fiber cross-sectional diameter, the change in the three-dimensional plane is facilitated (extruded short fiber-containing resin pellets are a good example), but the strand length to be cut If the fiber length is shorter than the strand diameter, or the single fiber length is shorter than the fiber diameter, the fiber direction is more out-of-plane and the fiber cut point per unit volume is increased. The amount of fibers per unit is significantly reduced, and the rigidity and strength contributed by the fibers per unit volume are significantly reduced.

Also, for the purpose of eliminating the difficulty of molding by prepreg sheet lamination along the three-dimensional shape surface, by a preform in which fibers are arranged on a molding die having a three-dimensional shape without impregnating the continuous fibers with resin. Methods are also being tried. When the fiber is not impregnated with resin, there is almost no restriction between the single fibers and between the fiber bundles, and the arrangement along the three-dimensional curved surface is relatively easy. However, in the production of a prepreg sheet in which fiber bundles are aligned in one direction, impregnation with a thermoplastic resin is not easy, and high pressure and a relatively long resin impregnation time are required. (Patent Document 2: Japanese Patent Application Laid-Open No. 11-269285) However, impregnation of a preform with a resin having a high viscosity such as a thermoplastic resin having a high molecular weight is accompanied by great difficulty.
On the other hand, there is a method of impregnating a monomer such as an epoxy resin having a low molecular weight with a resin mixed with a crosslinking agent, followed by crosslinking by heating to form a composite material having a three-dimensional curved shape, but there are difficulties in impact strength and recyclability. In addition, there is a need for further improvements in resin impregnation and curing time (Patent Document 3: JP 2012-77127 A).

Thus, when changing a plane to a three-dimensional curved surface, it is necessary to generate a large in-plane shear strain or in-plane tensile strain, but a unidirectional prepreg in which continuous fibers are stretched or almost stretched. In a woven fabric, it is almost impossible to generate a tensile strain in the fiber direction corresponding to the large shear strain and tensile strain required to transform a plane into a three-dimensional curved surface. Woven fabrics or unidirectional prepreg sheets can contain a large amount of fibers with a fiber content of 50% or more per unit volume. However, forming along a three-dimensional curved surface is difficult or has a relatively long forming time. is necessary.
A preform not impregnated with a resin that is relatively easy to deform along a three-dimensional curved surface requires a long impregnation operation after molding. In addition, a low-viscosity resin having a relatively short impregnation time has a small molecular weight, and has a long reaction time for making a polymer.
Sheets using short fibers can be deformed along a three-dimensional plane with relative ease, but fibers that cross and cross out of the plane are generated. In addition, the fiber content per volume is reduced due to the large space compared to the fiber volume at the fiber breaking point, and when reflected in the structure of high rigidity and strength that the fiber has when it is made a structure. .

JP 2014-28510 A JP-A-11-269285 JP 2012-77127 A

Unidirectional prepregs in which continuous reinforcing fibers are straightly arranged and impregnated with resin, woven prepregs in which fibers are relatively stretched, prepregs in which resin is impregnated and short fiber strands are dispersed on the surface, relatively long like papermaking In any prepreg in which fibers are dispersed on the surface, it is difficult to form a curved surface such as deep drawing along a three-dimensional shape even when the resin is softened by heating. This is because when the deformation is performed along the three-dimensional shape, a strain larger than the fiber breaking strain is generated in the fiber direction, and the prepreg is damaged.
When changing a plane to a three-dimensional curved surface, it is necessary to generate a large in-plane shear strain and in-plane tensile strain, but a unidirectional prepreg in which reinforcing fibers are stretched or a fabric that is almost stretched, Intertwined prepregs with relatively long fibers dispersed on the surface generate the tensile strain in the fiber direction corresponding to the large shear strain and tensile strain required to deform the plane into a three-dimensional curved surface without breaking the fiber. Almost impossible to do.
Accordingly, an object of the present invention was devised in view of the above circumstances, and is a resin-impregnated continuous reinforcing fiber prepreg capable of producing a molded product along a three-dimensional curved surface, a method for producing the prepreg, and molding from the prepreg. To provide a composite material.

The present inventor has arranged a reinforcing fiber in one direction, bent it with an appropriate amplitude with a period in its longitudinal direction, and a bent reinforcing fiber prepreg in which the resin is impregnated or semi-impregnated and kept bent in a three-dimensional curved surface. It was found that the molding having the above can be performed (see FIG. 1).
In order to form a three-dimensional curved surface shape by using these bending reinforcing fiber prepregs, a plurality of bending reinforcing fiber prepreg sheets were laminated with the longitudinal direction 5 of the fiber of the sheet and the peak and valley positions of the bending period being appropriately determined and laminated. The planar sheet resin is softened to facilitate expansion and contraction in the plane of the sheet, and the planar sheet is formed into a shape along a three-dimensional curved surface. After molding, when the thermosetting resin is impregnated, it is maintained at an appropriate temperature and cooled after curing, and in the case of a thermoplastic resin, it is quickly cooled to fix the three-dimensional curved surface shape. By appropriately determining the bending period 1 and the amplitude 2 of the prepreg sheet, large expansion / contraction along the longitudinal direction and expansion / contraction effect in the longitudinal direction and the vertical direction can be obtained.

  In addition to adjusting the bending period and amplitude of the fiber bundle according to the curvature and the curvature of the bending reinforcing fiber prepreg, the bending shape and shape of the three-dimensional curved surface to be molded are adjusted. By adjusting the bending period, amplitude, and bending shape of these fiber bundles according to the distribution of the fiber bundle, etc., it can be applied to any three-dimensional curved surface by a prepreg in which one sheet or a plurality of sheets are laminated. The elongation of the fiber bundle of the fiber reinforcing material can be maintained at an appropriate value within the formed surface.

In these bending reinforcing fiber prepregs, when the resin impregnated in the bending reinforcing fiber prepregs is softened and pulled in the longitudinal direction in a state where the viscosity is lowered, the fibers of the bent portion having an angle with the longitudinal direction are bent. As it expands, it shifts and grows as a whole. A portion having an angle with the longitudinal direction undergoes shear deformation, and as a result, extends in the longitudinal direction.
When the bending direction is 45 ° with the longitudinal direction and the fiber direction being ± 45 °, the regions where the fibers are bent and adjacent to each other are shifted by 45 ° within the plane by shifting the length corresponding to the diameter of the bending range of the fibers. However, the length in the longitudinal direction is about 1.414 times.
The diameter of the carbon fiber is around 7 μm, and the bending amplitude and period can be reduced according to the fineness of the carbon fiber.
This elongation is about 1.26 times in the longitudinal direction when the bending angle of the fiber of the bent fiber reinforced prepreg is 37.5 degrees, and the bending angle is changed to 50 degrees in the 90 degree direction in the longitudinal direction. It becomes about 1.26 times, and the size of elongation in the longitudinal direction and the direction perpendicular thereto is the same.
The same applies to compression.
When drawing a steel sheet, it is considered to be about 1.2 times as long as isotropic drawing, so it is possible to reproduce the deep drawing of the steel sheet with a bent prepreg. .

A sheet made of a bent fiber reinforced prepreg has a large partial anisotropy, but for example, a sheet in which the relative position in the longitudinal direction of the bent prepreg having a half-length amplitude and a half-length is shifted by a half cycle and stacked. When the four stacked sheets are laminated in four directions of 0 °, 90 °, and ± 45 °, respectively, pseudo isotropic property can be obtained.
That is, pseudo-isotropic property can be achieved with eight sheets. The fibers are bent in each sheet and the in-plane characteristics are not uniform, but the average elastic constant can be expected to be almost the same as the pseudo-isotropic characteristics formed by the unidirectional prepreg. The pseudo-isotropic sheet composed of 16 sheets that are laminated so that the laminated structure is symmetric in the thickness direction with the center plane sandwiched between two sheets of 8 sheets that constitute pseudo-isotropic Also has pseudo-isotropic properties.

When the bending angle is 15 ° or less, the elastic constant in the longitudinal direction is not significantly different from that of the unidirectional prepreg, so it is possible to stack a prepreg sheet with a small bending angle on the portion where the prepreg sheet does not require large elongation during molding. It is.
Alternatively, when the three-dimensional shape to be molded is asymmetrical, or when the curvature of the phase is partly different, the strain required at the time of molding is different, or the surface remains flat. The final three-dimensional molded body is obtained by determining the amplitude of the bending and the degree of bending of the reinforcing fiber according to the magnitude of strain required in those regions in advance for the portions to be maintained. In this case, the stretched fiber can be aligned and stretched according to the direction of the stress applied to the reinforcing fiber in the plane.
In this way, it is possible to exert the maximum strength of the reinforcing fiber as a three-dimensional molded body, but on the other hand, in accordance with the characteristics of the impregnated resin, the reinforcing fiber in the three-dimensional molded body It is also possible to give the molded body elongation and elastic deformation by leaving a certain degree of bending.

When an external force is applied to a carbon fiber reinforced resin composite material, a weak single fiber breaks and the fiber resin interface at the fractured part peels off, but the load applied to the broken fiber is transmitted to other fibers via nearby resin. The material will not break. As the load increases, damage gradually increases and breaks due to delamination of the composite material and extensive fiber breakage.
When the reinforcing fiber is a carbon fiber, the minimum radius (R) of the bent portion of the single fiber in the bent fiber reinforced prepreg can be about 0.5 mm to 1 mm. The tensile strain of the fiber generated at that time is as follows. The single fiber radius (r) is 3.5 μm.
0.7% to 0.35% (r / R) and 20% to 45% of the fiber breaking strain (about 1.5%), which may reduce the strength of the composite material. It is necessary to make the bending radius of the single fiber at 2 mm or more to avoid a decrease in strength. The elongation at break increases when the bent part of the fiber is localized in the pseudo-isotropic state and the fiber is bent.

As a specific form of the bent fiber reinforced prepreg of the present invention,
There are band-like fiber reinforced resin prepregs and sheet-like fiber reinforced resin prepregs obtained by impregnating a matrix resin between fibers of a fiber bundle composed of continuous fibers.
The present inventor has also found that a narrow tape-like bent fiber reinforced prepreg tape can be woven. A single layer or a plurality of the woven bent fiber reinforced prepreg sheets laminated and formed into a three-dimensional solid shape can be formed into a fiber reinforced composite material molded body having a more uniform laminated structure.
The fiber-reinforced composite material molded in this way maintained a state in which each fiber in the molded structure was properly stretched, and the tensile strength of the reinforcing fiber was exhibited to the maximum.

A method for producing the bent prepreg of the present invention;
(1) The reinforcing fiber bundles are aligned in the longitudinal direction so as to be flat, and are clamped by a jig over the entire width at right angles to the longitudinal direction and fixed so as not to be displaced in the longitudinal direction.
Each jig moves relative to each other by the bending amplitude at right angles to the longitudinal direction, and at the same time, forms a bending with a predetermined amplitude and periodic interval by filling the length, and impregnating with resin. Fix to the bent state. Since the bending period forms a peak and a valley with two adjacent jigs, a pair of jigs form one cycle of bending.
For the resin to be impregnated, the reinforcing fiber bundles are preliminarily arranged in a sheet shape, the material impregnated with the resin is sandwiched and fixed with a jig, softened by heating, bent, cooled and solidified, and fixed in that state. Alternatively, it may be applied to a jig and softened by heating to bend, or may be impregnated with a heat-melted resin after the reinforcing fibers are bent. Further, a fibrous resin or a sheet-like resin may be added along the fiber bundle, or a powdery resin may be attached and coated.
In order to perform the bending operation of the reinforcing fiber, it is necessary to form a slack necessary for bending by narrowing the longitudinal interval between the jigs sandwiching the reinforcing fiber. As a result, the alignment state is found and it is easy to deviate from the aligned plane, so that a means for pressing separately from the jig is provided between each jig, and the fibers are pressed by pressing toward the aligned plane. It is desirable to maintain an aligned state.

(2) As another manufacturing method,
The fiber bundles aligned so as to be flat are fixed with a plurality of jigs with a bending angle at predetermined intervals, and both ends of these jigs can be slid across two parallel guides. The fiber bundle is bent by passing the parallel guide through a bent course that changes the direction at the bending angle.
The jig passing through the bending portion of the parallel guide is perpendicular to the longitudinal direction of the fiber bundle, and the fiber bundle fixed to the jig is given a bending corresponding to the bending angle of the course of the parallel guide for each jig. .
As each jig slides along the parallel guide and passes through the bent portion, each fiber bundle is bent according to the bending angle of the course of the parallel guide, and at the same time, the fibers between the jigs. The bundle forms a slack necessary for bending the fiber according to the bending angle.
The fiber bundle is fixed in this state by solidifying the resin in a state where this bending is applied.
Note that it is preferable to press the fiber bundle between the jigs flatly in order to suppress the occurrence of fiber deviation and overlap due to bending and twisting of the fiber bundle during the bending operation, It is the same.
Further, the impregnation and fixing operations of the reinforcing fibers with the resin may be the same as the above manufacturing method.

(1) When a prepreg sheet of reinforcing fiber that is generally distributed is deformed along a three-dimensional curved surface, resistance to the elongation of the fiber inhibits deformation along the curved surface. For this reason, when forming into a three-dimensional shape having a curved surface, it is necessary to cut the sheet into small pieces where the curvature is large, and to stack the small pieces of sheets into a shape along the curved surface. Requires a lot of effort.
The prepreg sheet using the bending reinforcing fiber prepreg of the present invention can be easily deformed along a three-dimensional shape, even if it is a single sheet or a laminate of several sheets with different directions, and can be applied to manufacturing a part having a curved surface shape. As a result, it is possible to reduce the part molding cost and speed up the molding process.
(2) Simplification of production equipment and cost reduction Due to the above physical and economic effects, the present invention provides an excellent industrial quality composite material having a good curved surface and good uniformity of reinforcing fiber orientation. The member can be molded.
In particular, unlike conventional thermoplastic resin prepregs, the thermoplastic resin prepreg obtained by the present invention can be molded into composite structures of various shapes by hot pressing into a mold having a small radius of curvature. it can.

FIG. 1 is a conceptual diagram showing the structure of a bent fiber reinforced prepreg sheet of the present invention. FIG. 2 (Example 1) shows a method of bending by operating a jig for sandwiching and fixing a fiber bundle. FIG. 3 (Example 1) shows details of the bending process shown in FIG. FIG. 4 shows details of the operation of the clamping jig in the step of FIG. FIG. 5 shows a method of imparting bending by transferring the fixing jig for the fiber bundle along a parallel guide passing through a bent course (Example 2). FIG. 6 shows a conceptual diagram of an apparatus for continuously applying bending. The state which laminated | stacked the bending prepreg sheet | seat from which a half wavelength phase differs is shown.

[Production method 1 of bent prepreg]
FIG. 2 shows a method for producing a bent fiber reinforced prepreg.
In FIG. 2, a single fiber bundle or a plurality of fiber bundles 6 are aligned in the longitudinal direction, and a plurality of rod-shaped clamping jigs 7 are arranged perpendicular to and parallel to the longitudinal direction of the fibers. Clamp the fiber bundle and fix it. These fiber bundles are held in a wide line by the jig and linearly along the jig, and are fixed at a predetermined interval 9.
The jig 7 is moved along the longitudinal direction of the fiber, and every other adjacent jig 7 is moved 8 in the direction perpendicular to the longitudinal direction of the fiber in synchronism with this to bend the fiber bundle and adjacent jigs. Is narrowed according to the bending angle of the fiber bundle (interval 10).
At this time, the following jigs 7 are also moved in parallel in the longitudinal direction of the fiber bundle in synchronization.
In this way, every other jig that holds and fixes the fiber bundle is moved in a direction perpendicular to the fiber in accordance with the amount of bending, and the gap is narrowed and moved at the same time. The fiber bundle between the jigs is bent by moving in the fiber longitudinal direction.

In addition, in order to prevent the fibers in the bent portion from being bent and twisted due to the bending operation of the fiber bundle, the fiber bundle at the bent portion is pressed toward the arrangement surface by an alignment jig provided separately. Then, the alignment state is maintained by applying the tension.
After the bending operation, the fiber bundle is fixed in a bent state with an impregnating resin, but it is only necessary that the reinforcing fiber of the prepreg after the bending operation can be maintained in a state in which the bent state is maintained. The bundle may be impregnated or may be post-impregnated by imparting a bend, but a high viscosity thermoplastic resin or the like is a step of imparting a bend as a resin prepreg impregnated in a pre-aligned fiber bundle It is good to soften by heating.
Also, as a method of impregnating the fiber bundle with resin, it is attached to a jig, or along the reinforcing fiber bundle in the form of a fiber, sheet or powder, etc., and heated and melted during the bending operation. It may be softened, or may be impregnated and fixed after the bending operation.
In order to facilitate the removal of the prepreg from the apparatus, a release paper or a release agent may be applied in advance to a part such as a jig that contacts the melt-softened resin.

FIG. 3 shows the details of the manufacturing method step by step.
The carbon fiber bundle 6 is fed from the right side of the figure and is held from the front and back surfaces by jigs 7, 7-1, 7-2,... FIG. 3-A).
Next, the alignment jigs 11,... Are placed between these clamping jigs and pressed to maintain the tensioned state so that the fiber alignment state does not deviate, and the interval between the clamping jigs is bent. Narrow by half wavelength (FIG. 3-B).
The pair of alignment jigs and the holding jig positioned between them are moved vertically downward in the figure by the bending amplitude. At this time, the fiber 6 is bent and deformed, and at the same time, the alignment jig is pushed back to restore the bending of the fiber bundle (FIG. 3C).
The narrowed interval 10 of the clamping jig is a half wavelength of bending deformation, and the vertical movement 8 of the clamping jig and the pressing jig is the bending amplitude.
The step of imparting bending deformation to the carbon fiber may be performed by moving the fiber bundle according to these steps, and simultaneously supplying the clamping jig and the pressing jig from the right side of the drawing and repeating the above operation.

FIG. 4 shows an example of a structure comprising a parallel guide and a clamping jig for a mechanism for moving the clamping jig in the vertical direction to every other fiber while moving the clamping jig in the above-described bending process.
Holding jigs are arranged at regular intervals perpendicular to the moving direction of the prepreg (the longitudinal direction of the fiber), and hold the prepreg from above and below. In the drawing, a clamping jig having a small width on the lower side and a large or small thickness is used with respect to the clamping jig having a wider upper side (see the XY cross section).
Although the alignment jig 11 is omitted in the figure, the following operation is performed in conjunction with the clamping jig.
The holding jig is moved toward the left along the parallel guides 14 and 15 arranged on the upper and lower sides of the drawing while maintaining the interval through a spacer (not shown) by a pusher (push bar) 12.
Every other lower clamping jig has a different thickness (for example, 20 mm and 30 mm), and the thicker clamping jig is provided with a step difference in thickness (see D and C cross sections). ).
As shown on the left side of the figure, when these clamping jigs are transferred to the left while being placed on the parallel guide, the thin clamping jig is transferred on the parallel guide as it is (FIG. D). The holding jig having a thick cross section and a cross section A) has a protruding portion on the lower side of the parallel guide 14 on the upper side of the drawing, and a concave groove portion on the parallel guide 15 on the lower side of the drawing. The step portion of the thickness portion is guided by the projecting portion and the concave groove portion (C and B cross sections in FIG. C), and the thickness difference is pushed down to bend the prepreg.

[Bending prepreg manufacturing method 2]
FIG. 5 shows details of a manufacturing method in which a bending is performed by moving a jig holding a fiber bundle along a bent course of a parallel guide.
Are held and fixed at predetermined intervals by holding jigs 7-1, 7-2,... Having an angle corresponding to the bending angle Θ to be given to the fiber bundle 19 in which fibers are aligned in the longitudinal direction.
A guide for defining a path for moving the holding jig holding these fiber bundles is composed of two parallel guides 14 and 15 which can be slid by fitting both ends of the jig. Is arranged parallel to the fiber on the introduction side (right side) of the fiber bundle, that is, at an angle Θ with respect to the jig, and then changed in the direction toward the direction 18 bent at the angle Θ.
When the fiber bundle is transferred together with the clamping jig and moves in the moving direction 17 through the bending angle Θ toward the moving direction 18, the fiber bundle fixed to the clamping jig generates a slack necessary for bending between the jigs, and the bending angle. It is bent at Θ, and bending of a predetermined amplitude and angle is given.
Also in this case, a spacer for maintaining a predetermined distance between the holding jigs and an alignment jig for maintaining the alignment state of the fibers of the fiber bundle are arranged in the same manner as described above.

  The bending state of these fiber bundles is set to 360 ° in one cycle of peaks and troughs as in the case of the sine curve, and from 0 ° to 180 ° in one cycle because of the force applied when bending is applied. The bending shape is slightly different between 180 ° and 360 °. However, considering the use of a plurality of prepregs laminated in a pseudo-isotropic manner, there is little influence on strength reduction due to the difference in shape. By reducing the length of the period, the local characteristic deviation of the pseudo-isotropic laminate can be reduced.

FIG. 6 shows an overall conceptual diagram of an apparatus for continuously producing a bending reinforcing fiber prepreg.
The clamping jigs 55 and 56 for clamping the fiber bundle are fixed to the surfaces of the upper and lower timing belts 57 and 58 driven by the upper and lower sprockets 53 and 54, respectively, and are sent from the left side of the drawing. ) 51 is clamped and fixed between these clamping jigs and sent to a bending portion where alignment jigs 61 and 62 are arranged along a pair of parallel guides (not shown) arranged on the front and back sides of the figure.
The parallel guide changes the direction of the bending angle at the bending portion, and the holding jig imparts a predetermined bending to the fiber bundle.
On the left side of the apparatus, the bent prepreg 52 is removed with a tool 63, and the impregnated resin is cured (in the case of a thermosoftening resin) to complete the bending process.

In the manufacturing methods of Examples 1 and 2, the impregnating resin that is fixed in a bent state of the fiber bundle can be configured as follows.
When aligning the fiber bundle before bending the fiber bundle, a resin sheet is attached to both the upper and lower surfaces or one surface of the aligned fiber bundle, and a powdery resin is dispersed between the fibers, resin fiber and commingle It is assumed that each fiber bundle is wrapped like a sheath with a resin sheet or fiber, each single fiber is coated with resin, and some of them are applied to the fiber bundle at the same time it can.
In these embodiments, the relative movement between the single fibers is not constrained by the resin, and any resin may be used as long as the fiber bundle can be bent. When fixing the fiber bundle from above and below by the clamping jig, the resin is melted at the appropriate temperature by heating the jig to melt the resin, and the relative movement of the pressed part of the fiber is stopped to stop the resin. The movement of the resin can be fixed by a smaller pressing force compared to the case where there is no. The bent state can be fixed by impregnating the resin by heating and pressurizing the bent portion and cooling.

If the bundle of fibers is not accompanied by resin, when fixing the fiber bundle by pressing it from above and below with a jig, apply resin to the jig and heat it to an appropriate temperature to soften the resin. The relative movement of the fibers can also be stopped. The movement of the resin can be fixed by a smaller pressing force compared to the case without the resin. The bent portion can be fixed by cooling the bent portion after impregnation with resin.
In the case of a prepreg sheet in which the aligned fiber bundle is pre-impregnated with resin, the resin is softened by heating, and the fiber bundle is fixed by pressing from above and below with a jig. The bending can be fixed by cooling the resin.

[Manufacture of thermosetting resin prepreg]
Step 1
Ten carbon fiber bundles having a width of 7 mm, a thickness of 0.09 mm, and a number of fibers of 12,000 are aligned to produce a carbon fiber sheet having a width of 70 mm.
A mixture of an epoxy resin and a curing agent applied to a prepreg for curing at 125 ° C. is heated to 70 ° C. and applied to the coated paper surface at a thickness of about 0.08 mm.
The coated paper coated with the epoxy resin and the aligned carbon fiber sheet are overlapped and passed between rolls, and the resin is impregnated to prepare a prepreg.

Step 2
As a jig for sandwiching the prepreg from above and below, a stainless steel square bar having a cross section of 6 mm × 10 mm and a length of 300 mm is used. Each square bar has a 20 μm-thickness that has a mold release effect at a portion in contact with the prepreg. Encapsulated with plastic film.
Grooves engaged with the parallel guides are provided at both ends of each jig.
The prepreg having a length of 50 cm is heated to 60 ° C., clamped from both sides with a 6 mm-wide clamping surface of a pair of clamping jigs, and fixed at both ends of the pair of clamping jigs with clips, and further 12 mm × 10 mm A 15 mm stainless block was placed between the holding jigs to maintain a 12 mm interval.
The angle between the holding jig and the longitudinal direction of the prepreg was 45 °.

  The width along the longitudinal direction of the fiber for pressing and clamping the prepreg with the clamping jig needs to be about twice the thickness of the prepreg so that the pressing force is transmitted to the fiber. In the case of carbon fibers, even a fiber bundle that is sufficiently spread with spread fibers is at least about 20 μm. If it calculates from there, the pressing width of 40-50 micrometers will be needed. Although it depends on the characteristics of the fiber, if the strain is reduced to about 1/10 of the strain generated at the minimum bending radius of short fibers, the minimum bending radius is about 2 mm. As described above, the minimum fiber bending wavelength in this prepreg manufacturing method is 40 μm + 4 mm and the pressing width is 40 μm.

Step 3
Engage the grooves at both ends of the holding jig that fixed the prepreg with a parallel guide that changes the direction of movement from 45 ° to 0 °, and transfer the prepreg supported by the holding jig along the parallel guide. did.
8 mm to prevent the prepreg from bending and deviating from the plane of the prepreg when the prepreg undergoes bending deformation at a position where the angle of the parallel guide changes from the 45 ° section to the 0 ° section as the clamping jig moves. A stainless steel square bar measuring 8 mm x 150 mm is placed on the prepreg between the holding jigs as an alignment jig that presses the prepreg surface, presses the prepreg with its own weight, applies tension, and heats from below to 60 ° C. Kept. (See Figure 5)
After bending the prepreg, the prepreg was transferred while being cooled, and when it was solidified, the clamping jig was removed from the prepreg, and the prepreg was pressed with a flat plate from both sides at room temperature to finish it smoothly.
As the prepreg was transferred, a clamping jig was added to clamp and fix the prepreg, and the prepreg was successively introduced into the inclined section of the parallel guide and fed to continuously perform bending.

[Extension evaluation of thermosetting resin bent prepreg]
The prepreg manufactured in the above process is cut to a length of about 20 cm, both ends are fixed with a jig, and sandwiched between release papers from above and below on a flat plate so that a uniform pressure is applied to the prepreg with a force of 2 kg. Pressed.
This was heated to 80 ° C. and pulled through jigs fixed to both ends of the prepreg to extend the prepreg. The prepreg stretched straight with almost no resistance, and the prepreg fibers did not show any significant disturbance and stretched almost uniformly.

Evaluation of extensibility of laminated bent prepreg having a phase difference due to a half-wavelength difference (see FIG. 7).
Two prepregs cut to a length of about 20 cm were stacked while being shifted by about 9 mm, which is half the bending wavelength, and stretched under the same conditions as described above.
The prepreg stretched straight with almost no resistance, and the prepreg fibers were not disturbed and stretched almost uniformly.

[Evaluation of extensibility in the width direction (90 degree direction) of bent prepreg]
The prepreg produced in the above process is cut into a length of about 20 cm, and two bent prepregs having a size of 20 cm × 10.7 cm are arranged on a plane so as not to have a gap, thereby forming a sheet of about 20 cm × 20.7 cm. 6 were prepared, and 3 laminated prepregs were produced by laminating the bending wavelength by half a wavelength for each 2 sheets.
Next, these laminated prepregs are laminated at 0 °, 90 °, 0 ° in the longitudinal direction of the bent prepreg, and stretched in the 0 ° direction at 80 ° C. while pressing with a force of 2 kg under the same conditions as in Step 5. Stretched to 20%.
The bent prepreg stretched straight with almost no resistance, and the fiber stretched almost uniformly with no disturbance.

[Manufacture of thermoplastic resin bent prepreg]
Step 1
A carbon fiber prepreg sheet having a width of 7 cm was cut out from a carbon fiber prepreg having a matrix resin of PA6 of Ten Cate, product number TC910.

Step 2
As a jig for clamping the prepreg from above and below, a square bar with a cross-sectional shape of 6 mm x 10 mm and a stainless steel square bar with a length of 30 cm are used, and grooves for engaging and moving parallel guides at both ends of each jig. Provided.
The prepreg is cut to a length of 50 cm, heated to 230 ° C., and clamped so that the angle in the longitudinal direction of the clamping jig and the prepreg is 45 ° at intervals of 12 mm from the top and bottom on the 6 mm wide surface of the pair of clamping jigs. It fixed and the both ends of the clamping jig were fixed with the clip, and it prevented that a prepreg moved with respect to the clamping jig.
The interval between the holding jigs was maintained to be 12 mm through a 12 mm × 10 mm × 15 mm stainless steel block. A clamping jig heated to about 230 ° C. was used. Until the prepreg was bent, the temperature of the prepreg was prevented from lowering by a far infrared heater from the bottom.

Step 3
The groove of the holding jig was engaged with the parallel guide, and the prepreg held by the holding jig was moved along the parallel guide.
According to the movement of the clamping jig, the prepreg is heated to 230 ° C. at the location where the 45 ° section where the clamping jig is introduced into the parallel guide is shifted to 0 ° section, and is heated to about 230 ° C. 8 mm × 8 mm × 150 mm made of stainless steel The prepreg was bent from above by pressing the prepreg with its own weight, and the bent prepreg was bent, moved and solidified while cooling, and the clamping jig was removed from the prepreg.
Thereafter, the bent prepreg was heated to 230 ° C. and sandwiched between flat plates heated to 230 ° C. from the top and bottom to finish the surface smoothly.
With the progress of the prepreg bending operation, a new holding jig was added, and the prepreg was fed toward the 45 degree section of the parallel guide at an angle of 45 degrees with respect to the longitudinal direction of the prepreg at 12 mm intervals.

[Evaluation of stretchability of thermoplastic resin bent prepreg]
Cut the prepreg produced above to a length of about 20 cm, fix both ends with a jig, and sandwich it with release paper from above and below on a flat plate and press it so that a uniform pressure is applied to the prepreg with a force of 2 kg. It was. This was heated to 240 ° C. and pulled with a jig fixed to both ends of the prepreg to extend the prepreg. The prepreg stretched straight with almost no resistance. There was no significant disturbance in the prepreg fibers.

[Stretching evaluation of laminated thermoplastic resin bent prepreg with half-wavelength difference (see Fig. 7)]
A sample was prepared by laminating two prepregs cut to a length of about 20 cm while shifting the length of half the bending wavelength by about 9 mm, and stretched at 230 ° C. as described above. The prepreg stretched straight with almost no resistance, and no significant disturbance was observed in the prepreg fibers.

[Evaluation of stretchability in the width direction (90 ° direction) of thermoplastic resin bent prepreg]
Two sheets of 20 cm × 10.7 cm bent prepregs cut to a length of about 20 cm were arranged so as not to have a gap, and six sheets of about 20 cm × 20.7 cm were prepared.
Three laminated prepregs were prepared by laminating two of these 20 cm × 20.7 cm sheets with the bending wavelength shifted by a half wavelength, and the longitudinal direction of the bent prepreg was changed to 0 degree, 90 degrees, and 0 degree and laminated. Samples were prepared and extended in the same manner as described above at 240 ° C. in the 0 ° direction until the elongation was 25%. The prepreg stretched with little resistance.

[Manufacture of thermoplastic resin bent prepreg]
Step 1
A carbon fiber prepreg sheet having a width of 7 cm was cut out from a carbon fiber prepreg using Ten Cat's product number TC910 PA6 as a matrix resin.

Step 2
As the lower holding jig for holding the prepreg from above and below, stainless steel flat bars having a thickness of 1 mm and a length of 30 cm and having a width of 20 mm and a width of 30 mm were used. The upper clamping jig used was a 6 mm × 15 mm stainless steel rod having a length of 30 cm. Each flat bar is supported in parallel by two parallel guides, moves in parallel, moves in the longitudinal direction of the prepreg for each pair of clamping jigs, and moves to a predetermined distance in the vertical direction. The configuration is such that a typical bend is imparted.
Cut the prepreg from step 1 to 50 cm in length and heat it to 230 ° C., perpendicular to the longitudinal direction of the clamping jig and the prepreg at a distance of 13 mm from the top and bottom with a 1 mm wide surface and a 6 mm surface from the top. The both ends of the holding jig were fixed with clips so that the prepreg was not moved relative to the holding jig.
A stainless steel block having a thickness of 8 mm × 10 mm × 40 mm was interposed between the jigs, and the interval of 8 mm was maintained. Due to the shape of the lower holding jig and the shape of the parallel guide, when the holding jig moves along the parallel guide, every other pair of holding jigs is moved 7.5 mm in the direction perpendicular to the longitudinal direction of the prepreg. Bending was given.

Step 3
Move the prepreg clamped by the clamping jig along the parallel guide with the pusher,
In the section where the prepreg is bent, the prepreg is heated to 230 ° C., and the prepreg is pressed from above by the weight of a stainless steel square bar of 4.5 mm × 15 mm × 150 mm heated to about 230 ° C. The direction interval was narrowed and moved in the direction of 90 ° with respect to the longitudinal direction of the prepreg (the interval between the holding jigs was reduced from 13 mm to 10 mm, and moved to 90 ° direction with respect to the longitudinal direction of the prepreg by 7.5 mm) .
Further, the block of 8 mm × 10 mm × 40 mm in Step 2 was replaced with a block of 5 mm × 10 mm × 40 mm so that the interval of the holding jig was 5 mm.
After the bending operation of the prepreg, the nip was removed from the solidified prepreg by moving while cooling. Thereafter, the bent prepreg was heated to 230 ° C. and pressed with a flat plate heated to 230 ° C. from above and below to finish the surface smoothly.
Further, as the prepreg bending operation progressed, a new clamping jig was added at the rear, and the prepreg was clamped and fed to the parallel guide.

[Extension evaluation of thermoplastic resin bent prepreg]
The prepreg manufactured in the above process is cut into a length of about 20 cm, both ends are fixed with a jig, and sandwiched between release papers from above and below on a flat plate so that a uniform pressure is applied to the prepreg with a force of 2 kg. Pressed against. This was heated to 230 ° C. and pulled with a jig fixed to both ends of the prepreg to extend the prepreg. The prepreg stretched straight with almost no resistance. There was no significant disturbance in the prepreg fibers.

[Evaluation of extensibility of laminated thermoplastic resin bent prepreg laminated at half-wavelength difference (see Fig. 7)]
The prepreg produced in the above process was cut to a length of about 20 cm, and two prepregs were laminated while being shifted by about 11 mm, which is half the bending wavelength.
The sample was stretched by heating to 230 ° C. under the same conditions as described above. The prepreg stretched straight with almost no resistance, and no significant disturbance was observed in the prepreg fibers.

[Evaluation of width direction (90 ° direction) of thermoplastic resin bent prepreg]
The prepreg produced in the above process was cut into a length of about 20 cm, and three bent prepreg prepregs having a size of 200 mm × 77.5 mm were arranged so as not to have a gap, and six sheets having a size of about 200 mm × 217.5 mm were prepared. .
Three laminated prepregs were prepared by laminating two of these 200 mm × 217.5 mm sheets by shifting the bending wavelength by half a wavelength. Samples were prepared by changing the longitudinal direction of the bent prepreg at 0 degrees, 90 degrees, and 0 degrees.
The sample was stretched at 230 ° C. in the 0 ° direction until the elongation reached 25%. The prepreg stretched with little resistance, and almost no fiber disturbance was observed.

  The bending fiber reinforced prepreg of the present invention can be formed along a three-dimensional curved surface shape as well as the drawing processing of steel sheet, and exhibits the reinforcing performance of the reinforced fiber to the maximum, compared with the conventional fiber reinforced prepreg. Since the bent fiber reinforced material as the molded product can be obtained at low cost, it can greatly contribute to the field in the industry.

1 Bending period (wavelength)
2 Bending amplitude 3 Bending angle 4 Reinforcing fiber 5 Longitudinal direction of reinforcing fiber 6, 19, 20, 51 Aligned carbon fiber bundle (prepreg)
7, 7-1, 7-2,... Holding jig 8 Vertical movement amount of the holding jig 9 Jig interval 10 Distance after the parallel movement of the holding jig 11 Alignment jig 12 Pusher 13 Bending angle (Θ)
14, 15 Parallel guide 16, 52 Bent carbon fiber bundle (prepreg)
17, 18 Jig movement direction (Parallel guide course)
53, 54 Upper and lower sprockets 55, 56 upper, lower clamping jigs 57, 58 Upper, lower timing belt 59, 60 Sprocket rotation direction 61, 62 Fiber disturbance caused by bending of carbon fiber when bent Pressing jig (alignment jig) to prevent
63 Removal of resin-impregnated bent prepreg.

Claims (13)

In the reinforced fiber resin prepreg using continuous fibers,
In the state where each reinforcing fiber is parallel and aligned along the longitudinal direction in a plane and aligned and bent, the bending shape of each single fiber is equally aligned and bent within one period, and fixed by a matrix resin.
Reinforced fiber resin prepreg capable of deep drawing, characterized by enabling large shear deformation. As the fiber bundle fixed by a matrix resin, the reinforcing fibers are bent in the same direction in the plane in parallel and aligned along the longitudinal direction, and the single fibers are bent in the same shape and bent in one cycle. The reinforced fiber resin prepreg capable of deep drawing according to claim 1, wherein the fiber bundle is woven. As the fiber sheet fixed with a matrix resin, the reinforcing fibers are bent in the same direction in the plane in parallel and aligned along the longitudinal direction, and the single fibers are bent in the same shape and bent in one cycle. The reinforced fiber resin prepreg capable of deep drawing according to claim 1, wherein the sheet is formed by laminating a plurality of sheets. The deep-drawable prepreg according to claim 1, wherein the resin is a thermoplastic or thermosetting resin. A composite material molded by the deep-drawable prepreg according to claim 1. (1) aligning the reinforcing fibers along the longitudinal direction of the fibers,
(2) The fibers are sandwiched by a plurality of jigs that intersect with the fibers at right angles and are spaced in parallel to each other, and are fixed linearly along the jigs.
(3) Next, every other jig that sandwiches and fixes these fibers moves in the direction perpendicular to the longitudinal direction of the fibers and at the same time narrows the interval, thereby periodically with respect to the fibers between the fixed jigs. Give the fibers a right-angled bend,
(4) At the same time, pressing against the fiber surfaces that have been aligned to suppress deviation from the fiber alignment surface (5) impregnating with resin and fixing in a bent state,
A method for producing a prepreg capable of deep drawing. In (2), a molten resin is applied to a jig, the fiber is bent, and then heated in (5) to impregnate the fiber with the resin. 6. A method for producing a prepreg capable of deep drawing according to 6. In the above (1), a sheet-like resin or a felt-like resin fiber is added to the reinforcing fiber in advance, or a powder-like resin is mixed, or a fibrous resin is mixed, or a combination of these is used. The method for producing a prepreg capable of deep drawing according to claim 6 , wherein after bending is applied to the fiber, the resin is impregnated and fixed between the fibers by heating in (5). In the above (1), the reinforcing fiber aligned along the longitudinal direction of the fiber is a unidirectional prepreg impregnated with a tape-like or sheet-like resin, and this is heated to soften the resin.
The method for producing a prepreg capable of deep drawing according to claim 6 . (1) The reinforcing fibers are aligned in the longitudinal direction,
(2) The fibers are sandwiched by a plurality of jigs arranged in parallel at an angle corresponding to the bending degree to be imparted with respect to the longitudinal direction, and fixed obliquely in a linear shape,
(3) While bending the jig between the jigs by returning the angle while maintaining a parallel interval,
(4) At the same time, by pressing toward the surface on which the fibers between the jigs are formed, twisting and overlapping due to fiber bending are prevented,
(5) Then, the resin is impregnated to fix the bent state of the fiber.
A prepreg manufacturing method capable of deep drawing. In (2) above, applying a molten resin in advance to the jig,
The prepreg manufacturing method capable of deep drawing according to claim 10 . In the above (1), a sheet-like resin or a felt-like resin fiber is added to the reinforcing fiber in advance, or a powder-like resin is mixed, or a fibrous resin is mixed, or a combination of these is used. After imparting a bend to the resin, heating in (5) above to impregnate and fix the resin between the fibers,
The prepreg manufacturing method capable of deep drawing according to claim 10 . In the above (1), the reinforcing fiber aligned in the longitudinal direction of the fiber is a unidirectional prepreg impregnated with a tape-like or sheet-like resin, and this is heated to soften the resin,
The prepreg manufacturing method capable of deep drawing according to claim 10 .

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