JP2017171894A - Notch prepreg and manufacturing method of notch prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intermediate substrate excellent in followability to three-dimensional shape and exhibiting good surface quality and high physical properties when made as a fiber reinforced plastic.SOLUTION: There is provided a notch prepreg having a plurality of notches cutting a reinforced fiber in at least a part of area of a prepreg containing monoaxially oriented reinforced fiber and a resin, having average of population of 10 or more and variation coefficient within 20% when the number of notches contained in 10 circle small areas with diameter of 10 mm optionally selected from the area is recognized as the population.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cut prepreg suitable as an intermediate base material for fiber-reinforced plastic having good shape following property at the time of molding and having high mechanical properties when solidified, and a method for producing the same.

  Fiber reinforced plastics composed of reinforced fibers and resins are attracting attention in industrial applications because they have high specific strength, high specific modulus, excellent mechanical properties, and high functional properties such as weather resistance and chemical resistance. Deployed in structural applications such as aircraft, spacecraft, automobiles, railways, ships, electrical appliances, sports, etc., the demand is increasing year by year.

  As an intermediate base material for fiber reinforced plastic, there is SMC (sheet molding compound). SMC is a sheet-like base material in which chopped strands that are usually cut to about 25 mm and impregnated with a thermosetting resin are randomly dispersed, and is suitable as a material suitable for molding fiber-reinforced plastic having a complicated three-dimensional shape. Are known. However, fiber reinforced plastics molded by SMC inevitably cause uneven distribution and orientation unevenness of chopped strands, so that the mechanical properties of the molded body are lowered or the variation of the values becomes large. As a method for molding a fiber reinforced plastic that stably exhibits high mechanical properties, a method is known in which a continuous reinforced fiber is laminated with a prepreg impregnated with a resin and molded by an autoclave. However, in a prepreg using continuous fibers, wrinkles and stretching of reinforcing fibers occur due to insufficient deformability, and it is difficult to form into a complicated shape such as a three-dimensional shape.

  In order to fill the drawbacks of the materials as described above, the prepreg made of continuous reinforcing fiber and resin is cut to divide the reinforcing fiber so that it can flow and the variation in mechanical properties is reduced. A base material is disclosed (for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 63-247010 Japanese Patent No. 5167953

  The methods described in Patent Document 1 and Patent Document 2 have significantly improved mechanical properties and reduced variations compared to SMC. However, Patent Document 1 cannot be said to have sufficient strength to be applied as a structural material. There is room for improvement in three-dimensional shape tracking. In addition, Patent Document 2 has a problem in that, although higher strength is exhibited and the three-dimensional shape followability is good, the prepreg contrast and the surface quality are inferior due to the opening of the notch during molding.

  In view of the background art, the present invention provides an intermediate base material (cut prepreg) that is excellent in three-dimensional shape followability and can obtain a fiber-reinforced plastic that exhibits high surface quality and excellent mechanical properties when solidified. It is to provide.

The present invention employs the following means in order to solve such problems. That is:
(1) A cut prepreg having a plurality of cuts for dividing the reinforcing fiber in at least a partial region of the prepreg including the reinforcing fiber and the resin oriented in one direction, and is arbitrarily selected from the region. An incision prepreg in which the average value of the population is 10 or more and the coefficient of variation is within 20% when the number of incisions contained in 10 small circular regions having a diameter of 10 mm is a population.
(2) A method for producing a cut prepreg having a plurality of cuts for dividing the reinforcing fiber in at least a partial region of the prepreg containing the reinforcing fiber and the resin,
A method for manufacturing a cut prepreg, comprising: a step 1 for inserting a plurality of cuts 1 into a prepreg; and a step 2 for inserting a plurality of cuts 2 that do not overlap the cuts 1 with respect to the prepreg.

  According to the present invention, it is possible to obtain an intermediate substrate that is excellent in three-dimensional shape followability and exhibits good surface quality and excellent mechanical properties when a fiber reinforced plastic is used.

It is a conceptual diagram of the cutting prepreg of this invention. A non-uniform cut pattern (a) and a homogeneous cut pattern (b, c) are illustrated. It is an example of the cutting pattern used for the cutting prepreg of this invention. It is an example of the cutting pattern used for the cutting prepreg of this invention. It is an example of the cutting pattern used for the cutting prepreg of this invention. It is an example of the cutting pattern used for the cutting prepreg of this invention. This is a press mold. It is six examples of the cutting pattern used for the cutting prepreg of this invention. It is five examples of the cutting pattern which is not used for the cutting prepreg of this invention. It is a small area extraction pattern in the cut prepreg in an Example.

  In order to obtain an intermediate base material that has excellent followability to a three-dimensional shape and expresses excellent mechanical properties when used as a fiber reinforced plastic, the present inventors have intensively studied, and reinforced fibers oriented in one direction In order to solve such a problem, a plurality of cuts for dividing the reinforcing fiber are inserted into at least a partial region of the prepreg containing the resin to make the reinforcing fiber discontinuous, thereby improving the follow-up to the three-dimensional shape. Investigated.

  Specifically, the number of cuts included in 10 circular 10 mm diameter small regions arbitrarily selected in a region where a plurality of cuts are inserted (hereinafter referred to as a cut region) is defined as a population. If the average value of the population is 10 or more and the coefficient of variation is 20% or less, the cut prepreg (the average value of the population is 10 or more is high density, and the coefficient of variation is 20% or less. Is called homogeneous).

  FIG. 1A shows a conceptual diagram of a cut prepreg including a cut area 3 in which a plurality of cuts 2 are inserted into the prepreg 1. As long as the cut area is in at least a part of the prepreg, the cut area may exist only in a part of the prepreg or in the entire prepreg, and a plurality of cut areas are included in the prepreg. May be. The incision area may exist in any part of the incision prepreg, but it exists in an area that includes a three-dimensional shape such as a curved surface or unevenness when molded with the incision prepreg into a fiber reinforced plastic. It is preferable to do. Even if all the reinforcing fibers are divided by the cutting in the cutting area, the reinforcing fibers that are not divided by the cutting may be included. Further, the angle formed by the orientation direction of the reinforcing fiber and the cut may be two or more, and the length of the reinforcing fiber divided by the cut may be two or more.

  FIG. 1B shows a state where ten circular small areas 4 having a diameter of 10 mm are extracted in the cut area 3 (hereinafter, the circular small areas 4 having a diameter of 10 mm are abbreviated as small areas). The small area is preferably extracted as densely as the small area does not overlap within the cut area, but the cut area is not large enough to extract all 10 small areas without overlapping. May be extracted so that the small regions overlap each other. However, in order to measure the average value and variation coefficient of the above-mentioned population more accurately, a small area should not be set beyond the boundary of the cut area. The boundary of the incision area is a line segment group connecting line segments connecting the ends of the notch, and all the incisions are included in the line segment group, and the total length of the line segment group is the smallest Is a line group.

  The number of cuts included in the small area is the total number of cuts existing in the small area and cuts partially contacting the outline of the small area. The average value of the population and the coefficient of variation of the population are calculated by Equations 1 and 2, respectively, where the number of cuts in the 10 small regions is ni (i = 1 to 10). The

  The higher the number of cuts, the better the followability to the three-dimensional shape, and the smaller each cut opening when the cut prepreg is deformed, the better when using fiber reinforced plastic. Surface quality can be obtained. In addition, even if the number of reinforcing fibers divided by cutting is the same as a whole, when a load is applied when using fiber reinforced plastic, if the cutting is large, the stress concentration around the cutting increases. However, as it becomes finer, stress concentration is reduced and mechanical properties are improved.

  Therefore, when the number of cuts included in the small area is counted in 10 small areas to make a population, it is preferable that the average value of the population is 10 or more. More preferably, it is 15 or more. In the small region, the same reinforcing fiber may be divided by a plurality of cuts, but if the fiber length L of the reinforcing fiber is smaller than 10 mm, the mechanical properties after solidification may be reduced. It is more preferable that the same reinforcing fiber is not divided by a plurality of cuts. In addition, as shown in FIGS. 2A to 2C, the fiber length L is a reinforcement that is divided by an arbitrary cut and a cut closest to the reinforcing fiber direction (cutting in pairs). Refers to the length of the fiber. When the average value of the population is larger than 50, the possibility that the same reinforcing fiber is divided by a plurality of cuts in the small region is high, and thus the average value of the population is preferably 50 or less. On the other hand, the more uniformly the cuts are distributed in the cut region, the smaller the variation of each cut opening when the cut prepreg is deformed. Is expressed. Therefore, the variation coefficient of the population is preferably 20% or less. More preferably, it is 15% or less. Here, as a method for extracting small regions, it is preferable to extract the small regions so that they are relatively close to each other as shown in FIG. In some cases, the variation coefficient may vary depending on the extraction pattern. In this case, if the variation pattern is measured five times and the variation coefficient is 20% or less four times or more, it is considered that the aspect of the present invention is satisfied.

  The concept of inserting a relatively small cut has already been described in Patent Document 2, but for example, the cut pattern described in FIG. 2 of Patent Document 2 is enlarged and reduced, and the average value of the population becomes 10 or more. In this case, the fiber length of the reinforcing fiber must be 10 mm or less, and when the fiber length of the reinforcing fiber is 10 mm, the average value of the population is 5 or less, and the distribution of the cuts. The density of becomes smaller.

  Moreover, in many existing cutting patterns represented by FIG. 1 (A) of patent document 1, it shows in FIG. 2 (a) (It is a figure of this specification when literature is not specified. The same hereafter). Thus, with respect to the length L of the reinforcing fiber, the adjacent cuts are shifted by a length L / 2 that is half of L to make intermittent cuts. In the case of such a cutting pattern, the shorter the cutting length and the longer the fiber length, the easier it is for the cutting to occur in a straight line that exists every other L / 2 in the orientation direction of the reinforcing fiber. The variation of the population increases. In such a case, the cut openings are concentrated on the straight line, and the openings appear remarkably. As shown in FIG. 2 (b), the adjacent cuts are shifted not by L / 2 but by a fine cycle such as L / 5 or L / 6, so that the cuts are evenly distributed in the cut prepreg. When the cut prepreg is stretched, the stretched portion is not biased and uniform deformation is possible, and the opening of each cut is suppressed (hereinafter the cuts are distributed evenly) The pattern is sometimes referred to as a uniform cut pattern). Further, the adjacent cuts may be shifted as shown in FIG. 2C instead of being shifted stepwise as shown in FIG. In FIG. 2C, the notch is shifted at a cycle of L / 10, but the reinforcing fiber bundles are divided by the incision, and ends of adjacent reinforcing fiber bundles (for example, the cuts in FIG. 2C). The distance between the cut s1 and the cut s2) is 2L / 5, which is longer than L / 5 in FIG. A long distance between the ends of adjacent reinforcing fiber bundles has the effect of suppressing crack propagation and chain of notch openings, and improves both mechanical properties and surface quality. In the case of FIG. 2 (a), the distance between the ends of adjacent reinforcing fiber bundles is as long as L / 2, but the distance between the two cuts sandwiching the reinforcing fiber bundle is also short, so the two cut openings The stress concentration part due to is easy to overlap, which is not preferable as a mechanical characteristic.

  The length of the reinforcing fiber after splitting is preferably 10 mm or more, more preferably 15 mm or more, and further preferably 20 mm or more. Even when the length of the reinforcing fiber is 20 mm or more, by reducing the number of reinforcing fibers divided by each cutting, a cutting pattern in which the cutting is distributed with high density (hereinafter, high-density cutting) In some cases, the effect of improving the mechanical properties can be expected due to the long reinforcing fibers and the small depth of cut. As shown in FIG. 2B, a uniform and high-density cutting pattern can be realized while maintaining the fiber length by shifting adjacent cuttings with a fine period. The same applies when the cut is inserted obliquely with respect to the orientation direction of the reinforcing fibers.

  As an aspect of the cut prepreg in the present invention, it is preferable that an arbitrary cut A and another cut B closest to the cut do not divide the same reinforcing fiber. Reinforcing fibers that are separated by the notches that are in closest contact with each other become relatively short reinforcing fibers, and this is a factor that degrades the mechanical properties of the fiber-reinforced plastic. Moreover, when there is a reinforcing fiber that is not divided by either the cutting A or the cutting B between the cutting A and the closest cutting B, the cutting A is obtained when the fiber is reinforced plastic. And the cut B are difficult to be connected due to damage, and the mechanical characteristics are improved.

  FIG. 3 shows a part of the incision region, and a plurality of reinforcing fibers 5 exist between the incision A and the closest incision B, and the incision A and the incision B have the same reinforcement. The fiber is not divided. As shown in FIG. 3 (a), the reinforcing fiber 5 between the cut A and the cut B may be divided by a cut C that is not closest to the cut A and the cut B. FIG. As shown in (b), the reinforcing fiber 5 between the cut A and the cut B may not be divided by the cut. The distance between the closest cuts is preferably 0.5 times or more of the projected length Ws obtained by projecting the cut on the plane perpendicular to the reinforcing fibers in the direction perpendicular to the reinforcing fibers, and more preferably 1 Ws. It is more than double.

  In the cutting prepreg in which the cuts are distributed at high density, the distance between the cuts becomes close, and when the closest cuts divide the same reinforcing fiber, very short reinforcing fibers are mixed. Therefore, by providing an interval so that the closest cuts do not divide the same reinforcing fiber, even if it is a high-density cutting pattern, mixing of short reinforcing fibers is suppressed and stable. Mechanical properties can be expressed.

  As a preferable embodiment of the cutting prepreg in the present invention, as shown in FIG. 4, the cutting is substantially the same length Y (hereinafter, Y is also referred to as the cutting length), and the distance between the closest cuttings 6 is a cutting prepreg longer than 0.5 times Y. Here, “substantially the same length” means that all the cut lengths are within ± 5% of the average value of all the cut lengths (the same applies hereinafter). In the present invention, the cut may be linear or curved, and in any case, the line segment connecting the ends of the cut is the cut length Y.

  The distance between the closest cuts means the shortest distance between the closest cuts. When the distance between the closest cuts is close, when the fiber reinforced plastic is damaged, damage becomes easy to connect the cuts, so the distance between the closest cuts is 0 of the cut length Y. It is preferably larger than 5 times. The distance between the closest cuts is more preferably 0.8 times Y or more, and still more preferably 1.0 times or more Y. On the other hand, there is no particular upper limit on the distance between the closest cuts, but when giving a high-density cut to the prepreg, the distance between the closest cuts should be 10 times the cut length Y or more. It's not easy.

  Incision prepregs with high-density distribution of cuts, the followability to the three-dimensional shape is improved, and improvement in mechanical properties can be expected due to the smallness of each cut, but the distance between the cuts is close The mechanical characteristics are further improved when the cuts are separated from each other. Therefore, when the cuts are inserted densely, the cut pattern in which the distances between the cuts are separated, that is, the distance between the closest cuts is made larger than 0.5 times the cut length Y. This is particularly important for improving mechanical properties. Furthermore, in the case of a cut prepreg in which all the reinforcing fibers are divided in the cut area to improve the shapeability, the shortest distance between the closest cuts is larger than 0.5 times the cut length Y. In addition, since the closest cuts do not cut the same reinforcing fiber, the mechanical properties can be expressed to the maximum without impairing the followability to the three-dimensional shape and the surface quality.

  As a preferable aspect of the cut prepreg in the present invention, a cut prepreg in which the cut is inserted obliquely with respect to the orientation direction of the reinforcing fibers can be mentioned. When the cut is curved, it means that the line segment connecting the ends of the cut is oblique with respect to the orientation direction of the reinforcing fibers. By making the incision oblique with respect to the orientation direction of the reinforcing fiber, it is possible to improve the followability to the three-dimensional shape of the incision prepreg and the mechanical characteristics when the fiber reinforced plastic is used. If the angle between the orientation direction of the reinforcing fibers and the cut is θ, θ is preferably 2 to 60 °. In particular, when the absolute value of θ is 25 ° or less, the mechanical properties, particularly the tensile strength, are remarkably improved. From this viewpoint, the absolute value of θ is more preferably 25 ° or less. On the other hand, if the absolute value of θ is smaller than 2 °, it becomes difficult to make a stable cut. That is, when the cut is laid on the reinforcing fiber, the reinforcing fiber easily escapes from the blade when cutting with the blade, and it becomes difficult to insert the reinforcing fiber while ensuring the positional accuracy of the cut. From this viewpoint, the absolute value of θ is more preferably 2 ° or more.

  Not only when the cuts are distributed at high density, but the smaller the absolute value of θ, the better the mechanical properties can be expected, while the cuts are close to each other, especially when all reinforcing fibers are cut within the cut region. Therefore, there is also a concern that the damage caused by the cutting is easily connected and the mechanical characteristics are lowered. However, an arbitrary cut and another cut closest to the cut do not sever the same reinforcing fiber, and the cut is substantially the same length Y and is closest. When the distance between the cuts is longer than 0.5 times Y, further improvement in mechanical properties can be expected as compared with the case where the cuts are perpendicular to the orientation direction of the reinforcing fibers. When the depth of cut is high, the improvement of surface quality can be expected by improving the mechanical characteristics and suppressing the opening of the cut. As represented by Patent Document 2, it is a known technique to insert a cut diagonally with respect to the reinforcing fiber, but it is adjacent as shown in FIG. 2 (f) and FIG. 12 of Patent Document 2. In the cutting pattern in which the cutting is shifted by L / 2 with respect to the fiber length L of the reinforcing fiber, when L is long and the cutting length is small, the same as the phenomenon shown in FIG. However, when the cutting prepreg is stretched, it becomes easy to stretch the parts where the cuts are dense, and even when fiber reinforced plastic is used, the cuts are close to each other. It is easy to cause a decrease in mechanical properties. Applying oblique notches to the uniform notch arrangement as shown in FIG. 2 (b) and FIG. 2 (c), more effectively manifesting the effect of improving the mechanical properties by inserting the notches obliquely. it can.

  As a preferred embodiment of the cutting prepreg in the present invention, the absolute value of the angle θ formed by the cutting and the orientation direction of the reinforcing fibers is substantially the same, and further, a cutting in which θ is positive (referred to as a positive cutting). An incision prepreg including an incision in which θ is negative (referred to as negative incision) can be mentioned. That the absolute value of θ is substantially the same means that the absolute value of the angle θ in all the cuts is within ± 1 ° of the average value obtained from the absolute value of the angle θ in all the cuts. By inserting not only positive cuts but also negative cuts into the cut prepreg, when in-plane shear deformation occurs near the positive cut when the cut prepreg is extended, reverse shear deformation occurs near the negative cut. As a result, the in-plane shear deformation can be suppressed and expanded as a macro.

  More preferably, it is a cutting prepreg including substantially the same number of positive cuttings and negative cuttings. The inclusion of substantially the same number of positive cuts and negative cuts means that the number of cuts for which θ is positive and the number of cuts for which θ is negative are substantially the same. The number of incisions for which θ is positive and the number of incisions for which θ is negative are substantially the same as the percentage based on the number, and the number of θ that is a positive angle and a negative number That is, the number of θs is 45% or more and 55% or less (the same applies hereinafter).

  As shown in FIG. 5, the positive cuts and the negative cuts are alternately arranged, so that it is easy to secure the distance between the adjacent cuts while inserting the cuts with high density. In addition, when laminating the obtained cut prepreg, in the case of a cut prepreg including only positive cuts or negative cuts, whether the prepreg is viewed from the table even if the prepregs are oriented in the same reinforcing fiber orientation The direction of the cut differs depending on whether it is viewed from the back. Therefore, when manufacturing fiber reinforced plastics, it is possible to increase the time and effort required to control the stacking procedure for stacking the same number of the same reinforcing fibers with different cutting directions so that the cutting direction is the same each time. There is sex. Therefore, the absolute value of the angle θ formed by the cut and the orientation direction of the reinforcing fiber is substantially the same, and if the cut pattern has substantially the same number of positive cuts and negative cuts, it is the same as a normal continuous fiber prepreg Stacking is possible by handling.

  In the case of a cutting prepreg with approximately the same number of positive cuts and negative cuts, and a cut pattern in which positive cuts and negative cuts are mixed uniformly, an arbitrary cut can be obtained, especially in the case of a high-density cut distribution. It is easy to create a notch pattern in which the distance between the closest notches is longer than 0.5 times Y without cutting the same reinforcing fiber with another notch closest to the notch. Become. Thereby, the connection of the damage which generate | occur | produced by the notch can be suppressed, and a dynamic characteristic improves. In addition, when there is a positive cut and a negative cut, it is difficult to find the opening of the cut even when the cut prepreg is stretched, and a good surface quality can be obtained when it is made of fiber reinforced plastic. In this case, the cut becomes finer, and a better surface quality can be obtained. The cutting pattern is also effective when dividing all the reinforcing fibers in the cutting region, and the mechanical properties and the surface quality can be improved while maintaining the followability to the three-dimensional shape. Also, when inserting a notch into the prepreg using a blade, when inserting only a positive cut or a negative cut, a force that moves the prepreg in the width direction acts when pushed out by the blade, so the prepreg Although it becomes easy to shift in the direction, by using a blade including approximately the same number of positive cuts and negative cuts, the prepreg becomes difficult to shift in the width direction, and the cuts can be inserted with high accuracy.

  More preferably, with respect to the interval between an arbitrary cut and another closest cut existing on the extended line of the cut, the length differs between the positive cut interval and the negative cut interval. It is a prepreg. FIG. 6 shows a cut prepreg in which approximately the same number of positive cuts and negative cuts are inserted. The positive cut is arranged on the straight line 9 and the negative cut is arranged on the straight line 10, and the interval between the positive cuts on the straight line 9 is smaller than the interval between the negative cuts on the straight line 10. By arranging the cuts in this way, it is possible to secure a uniform, high-density and close distance between adjacent cuts, and it is possible to create a cut pattern in which the closest cuts do not break the same reinforcing fiber. is there. Furthermore, with regard to the interval between an arbitrary cut and another closest cut existing on the extension line of the cut, the distance between the positive cuts and the gap between the negative cuts is the same as the length. The length of the reinforcing fiber can be increased, and the mechanical properties can be maintained even when the cuts are distributed at a high density. Note that the presence of a cut on the extension line of the cut means that the angle between the straight line extending the cut and the straight line connecting the closest points of the target cuts is within 1 °. .

  About the interval between any notch and another closest notch that exists on the extension line of the notch, it should be a notch pattern with different lengths between the positive notches and the negative notches. Thus, even if the density is high, the length of the reinforcing fiber can be made longer, and even when all the reinforcing fibers are divided in the cutting area, any cutting and the closest to the cutting With another cut, the same reinforcing fiber is not divided, and a cut pattern in which the distance between the closest cuts is longer than 0.5 times the cut length Y is easily obtained. As a result, the mechanical properties can be improved more effectively without impairing the surface quality and followability to the three-dimensional shape. In other words, approximately the same number of positive cuts and negative cuts are inserted, and the interval between an arbitrary cut and another closest cut existing on the extension line of the cut is the same as the interval between the positive cuts and the negative cut. The length differs depending on the interval between the cuts, and an arbitrary cut and another cut closest to the cut do not divide the same reinforcing fiber, and the distance between the closest cuts is the cut length The cut pattern, which is longer than 0.5 times the length Y and in which substantially all the reinforcing fibers are divided into fiber lengths of 15 mm or more in the cut region, has a three-dimensional shape following property, surface quality, and mechanical properties. From the viewpoint of, it is particularly preferable. As shown in FIG. 1, FIG. 2 (d), and FIG. 14 (d) of Patent Document 2, a cutting pattern in which a positive cutting and a negative cutting are inserted is known. As in FIG. 2 (a), the adjacent notch is a notch pattern in which the fiber length L of the reinforcing fiber is shifted by half, and as L becomes longer and the notch becomes smaller, the density of the notch arrangement becomes more dense. It becomes easy to do. The adjacent cuts are not limited to L / 2 as shown in FIG. 2B and FIG. 2C, but can be made a high-density and uniform cut pattern by shifting.

  In addition, when manufacturing a cut prepreg, a protective sheet is attached to the surface of the cut prepreg, and the adhesive is attached to the rotary blade roll and the cut prepreg by penetrating the protective sheet and inserting the cut into the prepreg. It may be suppressed. When laminating cut prepregs manufactured in this way, it is necessary to peel off the protective sheet. If the distance between the closest cuts is close, the protective sheet may be torn off when the protective sheet is peeled off, resulting in poor handling. There is. Therefore, also from the viewpoint of the handleability of the cut prepreg sheet, it is preferable that the distance between the closest cuts is longer than 0.5 times the cut length Y. When approximately the same number of positive cuts and negative cuts are mixed and arranged, when the protective sheet is peeled off, the cuts on the protective sheet are difficult to be connected, and the handleability of the cut prepreg sheet is further improved. If the length between an arbitrary notch and another notch closest on the extension line of the notch differs in length between the positive notches and the negative notches, The negative cuts can be arranged more uniformly, the protective sheet is hardly torn off, and the handleability of the cut prepreg is further improved. Typical materials for the protective sheet include polymers such as polyethylene and polypropylene. When inserting a notch into the prepreg with a blade, the role of preventing the resin from sticking to the blade, It has the role of protecting the cut prepreg surface from foreign substances such as dust during storage.

  In the present invention, the resin contained in the cut prepreg may be a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include polyamide (PA), polyacetal, polyacrylate, polysulfone, ABS, polyester, acrylic , Polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyetherimide (PEI), polyetherketoneketone ( PEKK), liquid crystal polymer, vinyl chloride, fluorine-based resins such as polytetrafluoroethylene, and silicone. Any thermosetting resin may be used as long as the resin undergoes a crosslinking reaction by heat to form at least a partial three-dimensional crosslinked structure. Examples of these thermosetting resins include unsaturated polyester resins, vinyl ester resins, epoxy resins, benzoxazine resins, phenol resins, urea resins, melamine resins, and polyimide resins. Deformation of these resins and resins of two or more blends can also be used. Further, these thermosetting resins may be resins that are self-cured by heat, or may include a curing agent, a curing accelerator, and the like. In addition, a filler may be included to improve heat resistance, conductivity, and the like.

  The reinforcing fiber contained in the cut prepreg of the present invention may be glass fiber, Kevlar fiber, carbon fiber, graphite fiber or boron fiber. Among these, carbon fiber is preferable from the viewpoint of specific strength and specific modulus.

  By setting the volume content Vf of the reinforcing fiber to 70% or less, the reinforcing fiber shifts in the cut portion, effectively suppresses bridging, and obtains the effect of suppressing shape defects such as shape followability and voids. Can do. From this viewpoint, Vf is more preferably 70% or less. Moreover, bridging can be suppressed as Vf is lower. However, when Vf is smaller than 40%, it is difficult to obtain high mechanical properties necessary for the structural material. From this viewpoint, it is more preferable that Vf is 40% or more. A more preferable range of Vf is 45 to 65%, still more preferably 50 to 60%.

  The cut prepreg may be manufactured using a prepreg in which a reinforcing fiber is partially impregnated with a resin (that is, a part of the prepreg is not impregnated). By using a cut prepreg in which the reinforcing fiber is partially impregnated with resin, the unimpregnated portion of the reinforcing fiber inside the prepreg becomes an in-plane flow path, and the air trapped between the layers of the cut prepreg during lamination Gases such as volatile components from the cut prepreg are easily discharged out of the cut prepreg (such a gas flow path is referred to as a degassing path). On the other hand, if the impregnation rate is too low, peeling may occur between the reinforcing fiber and the resin, and the workability may be inferior, for example, the cut prepreg may be broken in two at the non-impregnated portion when the cut prepreg is laminated. In addition, the impregnation ratio is preferably 10 to 90% because voids may remain unless the impregnation time during molding is long. From this viewpoint, the more preferable upper limit of the impregnation rate range is 70%, the more preferable upper limit is 50%, and the more preferable lower limit of the impregnation rate range is 20%.

  The cut prepreg of the present invention may have a resin layer on the surface thereof. Since the resin layer exists on the surface of the cut prepreg, an interlayer resin layer is formed between the cut prepregs when the cut prepreg is laminated. As a result, when an out-of-plane impact load is applied, cracks are induced in the flexible interlayer resin layer, and due to the high toughness due to the presence of the thermoplastic resin, peeling is suppressed, so that the residual compressive strength after the out-of-plane impact is reduced. It is suitable as a main structural material that requires high safety such as aircraft.

  The cut prepreg of the present invention can be laminated and applied to press molding or autoclave molding. The lamination method can be arbitrarily selected depending on the application, but pseudo-isotropic laminates and cross-ply lamination are particularly preferred in consideration of the suppression of warpage caused by thermal residual stress and the balance of mechanical properties. At the time of lamination, in order to further improve the fluidity of the laminated substrate, a substrate in which reinforcing fibers are randomly oriented, such as SMC, a resin film, or the like may be appropriately laminated.

  Below, the manufacturing method of the cutting prepreg which has a some incision which divides a reinforcement fiber in the at least one part area | region of a prepreg containing a reinforcement fiber and resin is demonstrated.

  The means for inserting the cut into the prepreg may be mechanically inserted using a blade or burned out with a heat source such as a laser. In order to insert the incision with higher density and higher accuracy, a method of pressing a roll having a blade disposed at a fixed position against the prepreg is preferable.

  As another preferable method of manufacturing the cut prepreg, the step 1 of inserting a plurality of cuts 1 into the prepreg, and the step 2 of inserting a plurality of cuts 2 that do not overlap with the cuts 1 into the prepreg, A method including Specifically, it is a device that inserts a notch by attaching a punching die with blades to the elevator and pressing the punching die against the prepreg. After inserting the notch 1, the prepreg or the elevator is moved to The method of inserting the notch 2 in the position which does not overlap with the notch 1 is mentioned. It is also a preferable means to use a rotary blade instead of the punching die. Further, the size and shape of the cut area may be different between the cut 1 and the cut 2.

  The manufacturing method of the cutting prepreg in this invention can be preferably used also when the cutting pattern has a notch with which the angle which the notch and the orientation direction of a reinforced fiber make differs. Specifically, the angle θ1 formed by the cut 1 and the reinforcing fiber is positive or negative, and the angle θ2 formed by the cut 2 and the reinforcing fiber is different from the angle θ1 formed by the positive and negative. In particular, when inserting a cut with a blade, it may be difficult to produce a blade in which blades with different angles are arranged at a high density. You can insert notches into the density.

  In addition, the manufacturing method of the cut prepreg in this invention is preferably applicable not only to the prepreg in which the reinforcing fibers are oriented in one direction, but also when the reinforcing form is a woven fabric or a random mat.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to the invention as described in an Example. In this example, the production of the cut prepreg, the density distribution of the cut, the followability to the three-dimensional shape, the quality on the surface of the fiber reinforced plastic, the tensile modulus, and the tensile strength were measured according to the following methods. FIGS. 8 and 9 each show a part of the cutting pattern used in the example and the comparative example, and each cutting pattern is repeated in the prepreg surface on the cutting prepreg. The results of Examples 1 to 7 and Comparative Examples 1 to 5 are as shown in Table 1.

<Manufacture of cut prepreg>
"Torayca" (registered trademark) prepreg sheet P3052S-15 (reinforced fiber: T700S, resin composition resin: 2500, volume content of reinforcing fiber: 56%, laminated with single-sided release paper) and a sheet provided with a blade A notch was inserted by pressing the prepreg sheet against a roll (rotary blade roll) wound around. In any of the examples, the incision region was the entire prepreg, and the incision pattern was such that all the incisions had the same length and the lengths of the reinforcing fibers divided by the incision. The prepreg sheet is supported by a release paper that is a sheet base A, and a polyethylene film is in close contact with the surface opposite to the release paper. At the time of inserting the cut, the polyethylene film was penetrated, and the cut was inserted into the release paper to about 50% of the thickness.

<Check cutting pattern of cutting prepreg>
In order to check whether the incision can be inserted into the incision prepreg as intended, after the incision is inserted, the surface of the incision prepreg is photographed with a digital microscope, and the incision is made using the measurement software of the digital microscope. Distribution, the length of the cut, the length of the reinforcing fiber divided by the cut, the angle between the orientation direction of the reinforcing fiber and the cut (cut angle), and the plane perpendicular to the orientation direction of the reinforcing fiber The projection length Ws projected onto the surface, the distance between the closest cuts, and the interval between the cuts existing on the extended line of the cut were measured. A plurality of photographed images were connected to measure a 50 mm × 50 mm region.

  First, the cutting pattern was extracted by extracting the line segment which connected the edge part of the cutting which exists on an image in all the cuttings. However, no line segment is extracted for the incision in contact with the edge of the image. On the image, 10 circular small regions having a diameter of 10 mm were drawn in a hexagonal close-packed arrangement as shown in FIG. 10, and the line segments included in each small region were counted. At this time, the line segment that touches the boundary of the small region is also considered to be included in the small region. The number of line segments included in the 10 small regions was used as a population, and the average value and variation coefficient of the population were calculated using Equation 1 and Equation 2.

  Regarding the length of the cut, the length of the line segment corresponds to the length of the cut, and the average value of the lengths of all the line segments existing on the image was calculated. If the length of all the line segments was within the range of the average value ± 5%, it was considered that all the cuts were substantially the same, and the average value was used as the representative value as the cut length.

  The cut angle was defined as an angle formed by the orientation direction (fiber direction) of the reinforcing fiber and the line segment. The average value is calculated by measuring the cutting angle in all line segments. If all the cutting angles are within the range of the average value ± 1%, it is considered that all the cutting angles are substantially the same. The average value was used as a representative value as the cutting angle. When positive cutting and negative cutting existed, the above calculation was performed using the absolute value of the cutting angle as a representative value.

  About the length of the reinforced fiber divided | segmented by cutting, it was set as the distance in the fiber direction of the line segment adjacent to a fiber direction. Three distances were measured for a set of line segments, and the average value was taken as the line segment distance, and the line segment distances were measured in the same manner for all extractable line segments. The average value of the distance between the line segments was the length of the reinforcing fiber divided by the cut.

  About Ws, about each line segment, it contact | connected the edge part of each line segment, the straight line parallel to the fiber direction was drawn, and it was set as the distance between these straight lines. The distance between the straight lines was measured for all the line segments, and the average value was set as Ws.

  The distance between the closest cuts was the shortest distance between the end of the line segment and the line segment closest to the end of any line segment. The shortest distance between the end portion and the closest line segment was measured for the end portions of all the line segments, and the average value was taken as the distance between the closest cuts with the representative location. In addition, when there are a plurality of reinforcing fibers that are not cut by the two cuts between the cuts closest to each other, any cut and another cut closest to the cut Incision was considered not to cut the same reinforcing fiber.

  About the space | interval of the notch which exists on the extended line of a notch, it measured when the positive notch and the negative notch existed. For regular cuts, a line segment extracted from any regular cut is extended, and there is a line segment that touches or approaches the line segment extracted from other regular cuts, and the center of the two line segments. When the angle between the straight line connecting the two and one of the line segments is 1 ° or less, it was considered that two line segments existed as one straight line. Like the distance 11 between the normal cuts in FIG. 6, the distance between the closest end points of the two line segments is the distance between the closest cuts. Similarly, regarding the negative cut, the distance 12 between adjacent cuts in the same straight line was measured.

<Checking surface quality after press molding>
The orientation direction of the reinforcing fiber of the cut prepreg is set to 0 °, and a 150 mm × 150 mm laminated body laminated on [+ 45/0 / −45 / 90] _2s is prepared, and press-molded with a mold having the shape shown in FIG. Went. The molding temperature was 150 ° C. and the press pressure was 3 MPa. The surface quality of the molded product was evaluated in the following three stages.

A: The incision is almost unrecognizable. B: The incision is recognized although the incision is small. C: The incision is large and the incision is conspicuous.

<Tensile modulus and tensile strength of fiber reinforced plastic>
A laminated body of cut prepregs of 300 mm × 300 mm from the cut prepreg and a laminated structure of [+ 45 / −45 / 0/90] _{2 s} was produced. At the time of lamination, the layers were laminated such that the surface from which the polyethylene film was peeled up. Then, the laminated body of the cut prepreg was press-molded under a surface pressure of 3 MPa with a press using a 350 mm × 350 mm mold to form a 350 mm × 350 mm fiber reinforced plastic. The temperature at the time of pressing was 130 ° C., held for 90 minutes after pressing, removed from the mold, and allowed to cool at room temperature. A test piece of 25 mm × 250 mm was cut out so that the 0-degree direction of the reinforcing fiber was the longitudinal direction, and a tensile test was performed by a method defined in ASTM D3039 (2008). The number of test specimens measured was 5 for each level, and the average values of tensile modulus and tensile strength were calculated as representative values.

(Example 1)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The length of the reinforcing fiber divided by the insertion of the cut is 8 mm, the projected length Ws obtained by projecting the cut on the plane perpendicular to the orientation direction of the reinforcing fiber is 1 mm, and the angle formed by the orientation direction of the reinforcing fiber and the cut is It was 90 °. The reinforcing fiber bundle divided by the cutting was arranged with a shift of 1/3 of the reinforcing fiber length L with respect to the adjacent reinforcing fiber bundle.

  The press-molded product had a notch opening on the surface. Although the length of the reinforcing fiber was short, the tensile modulus was high.

(Example 2)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The length of the reinforcing fiber divided by the incision is 12 mm, the projected length Ws obtained by projecting the incision on a plane perpendicular to the orientation direction of the reinforcing fiber is 0.64 mm, and the orientation direction of the reinforcing fiber and the incision are formed. The angle was 40 °. The cuts are substantially the same length Y = 1 mm, and the distance between the closest cuts is 1.7 mm, which is longer than 0.5 times Y. The reinforcing fiber bundle divided by the cutting was arranged with a shift of 1/6 of the reinforcing fiber length L with respect to the adjacent reinforcing fiber bundle.

  The press-molded product had a notch opening on the surface. The tensile elastic modulus was equivalent to that of Example 1, but the tensile strength was improved from that of Example 1.

(Example 3)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. As a result of confirmation after the insertion of the cut, an arbitrary cut and another cut closest to the cut did not divide the same reinforcing fiber. The cuts were substantially the same length Y = 1 mm, and the distance between the closest cuts was 1 mm, which was equivalent to Y. The length of the divided reinforcing fiber is 20 mm, the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber is 0.34 mm, and the angle formed by the orientation direction of the reinforcing fiber and the cut is 20 °. Met. An intermittent straight line was formed by a plurality of cuts.

  The surface quality of the press-formed product was the same as in Examples 1 and 2, but the tensile modulus and tensile strength were higher than those in Examples 1 and 2.

Example 4
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. As a result of confirmation after the insertion of the cut, an arbitrary cut and another cut closest to the cut did not divide the same reinforcing fiber. The cuts were substantially the same length Y = 1 mm, and the distance between the closest cuts was 1.5 mm, 1.5 times Y. The length of the divided reinforcing fiber was 20 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 0.34 mm. The angle formed by the orientation direction of the reinforcing fiber and the cut was 20 °. The reinforcing fiber bundles divided by the cutting were arranged so as to be shifted by 2/5 of the reinforcing fiber length L with respect to the adjacent reinforcing fiber bundles.

  The surface quality of the press-formed product was equivalent to that of Example 3, but the tensile strength was higher than that of Example 3.

(Example 5)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. When confirmed after the insertion of the cut, the cut was substantially the same length Y = 1 mm, and the distance between the closest cuts was 1.4 mm, 1.4 times Y. The length of the divided reinforcing fiber was 12 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 0.64 mm. The absolute value of the angle θ formed by the orientation direction of the reinforcing fiber and the cut was 40 °, and included approximately the same number of positive cuts where θ was positive and negative cuts where θ was negative.

  At the time of cutting prepreg manufacture, in the cutting pattern of Example 2, when the prepreg sheet was pressed against the rotary blade roll, the prepreg sheet tended to shift in the width direction as the pressed distance increased. In Example 5, the deviation in the width direction of the prepreg was small. At the time of lamination, there was a positive cut and a negative cut regardless of whether the release paper side or the polyethylene film side was on the top, so that the lamination could be done without making the back and front of the cut prepreg. Moreover, when the polyethylene film was peeled off in the cutting pattern of Example 2, the polyethylene film was easily torn off, but in Example 5, the polyethylene film could be peeled off without being torn off.

  Although the cut opening was seen in the press-formed product, it was harder to see than in Example 2. The tensile elastic modulus and tensile strength were the same values as in Example 2.

(Example 6)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. As a result of confirmation after the insertion of the cut, an arbitrary cut and another cut closest to the cut did not divide the same reinforcing fiber. The cuts were substantially the same length Y = 1 mm, and the distance between the closest cuts was 1.5 mm, 1.5 times Y. The length of the divided reinforcing fiber was 20 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 0.34 mm. The absolute value of the angle θ formed by the orientation direction of the reinforcing fiber and the cut is 20 °, and includes approximately the same number of positive cuts where θ is positive and negative cuts where θ is negative. Furthermore, the interval between the cuts existing on the extended line of the cut was different between the positive cut (3.4 mm) and the negative cut (24.5 mm).

  In the press-formed product, almost no cut opening was seen. The tensile elastic modulus and tensile strength were higher than those in Examples 3 and 4.

(Example 7)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. As a result of confirmation after the insertion of the cut, an arbitrary cut and another cut closest to the cut did not divide the same reinforcing fiber. The cuts were substantially the same length Y = 1 mm, and the distance between the closest cuts was 1.8 mm, which was 1.8 times Y. The length of the divided reinforcing fiber was 24 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 0.34 mm. The absolute value of the angle θ formed by the orientation direction of the reinforcing fiber and the cut is 20 °, and includes approximately the same number of positive cuts where θ is positive and negative cuts where θ is negative. Furthermore, the interval between the cuts existing on the extended line of the cut was different between the positive cut (33.3 mm) and the negative cut (44.7 mm).

  In the press-formed product, almost no cut opening was seen. The tensile strength was higher than that in Example 6.

(Comparative Example 1)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The notch and another notch closest to the notch may break the same reinforcing fiber, and the distance between the closest notches is 0.5 times the length of the notch There was a shorter section. The length of the divided reinforcing fiber is 20 mm or less, the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber is 1 to 2 mm, and the angle θ formed by the orientation direction of the reinforcing fiber and the notch is It was inserted randomly in the range of 90 °.

  In the press-formed product, there was a portion where the cut was greatly opened. The tensile strength was lower than any of Examples 1-7.

(Comparative Example 2)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The cut and another cut closest to the cut may have split the same reinforcing fiber. The length of the divided reinforcing fiber was 20 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 5 mm. The angle θ formed by the orientation direction of the reinforcing fiber and the cut was 40 °.

  The surface of the press-formed product had a large opening. The tensile elastic modulus and tensile strength were higher than those of Comparative Example 1, but were lower than those of Examples 3, 4, and 6 having the same reinforcing fiber length.

(Comparative Example 3)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The cut and another cut closest to the cut may divide the same reinforcing fiber. The length of the divided reinforcing fiber was 20 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber was 5 mm. The absolute value of the angle θ formed by the orientation direction of the reinforcing fiber and the cut is 40 °, and includes substantially the same number of positive cuts where θ is positive and negative cuts where θ is negative.

  The surface of the press-molded product was smaller than that of Comparative Example 2 although a cut opening was observed. The tensile strength was slightly improved as compared with Comparative Example 2.

(Comparative Example 4)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. A continuous cut was inserted, the length of the cut reinforcing fiber was 20 mm, and the angle θ formed by the cut and the orientation direction of the reinforcing fiber was 20 °.

  The surface of the press-formed product had a large opening. The tensile strength was higher than that of Comparative Example 3.

(Comparative Example 5)
The cutting pattern of the cutting prepreg was a cutting pattern as shown in FIG. The cut has substantially the same length Y = 1 mm, the length of the cut reinforcing fiber is 24 mm, and the projected length Ws obtained by projecting the cut on a plane perpendicular to the orientation direction of the reinforcing fiber is 0.34 mm. Met. The absolute value of the angle θ formed by the orientation direction of the reinforcing fiber and the cut was 20 °. When the position of the small area was changed, there was a pattern with a coefficient of variation exceeding 80%.

  Although the fiber length divided by the cut and the absolute value of θ were the same, the surface of the press-molded product had a large cut and a low tensile strength compared to Example 7. .

1: Prepreg 2: Incision 3: Area having a plurality of incisions for dividing the reinforcing fiber (incision area)
4: 10 mm diameter circular small region 5: Reinforcing fiber 6 between cut A and cut B: Distance between the closest cuts 7: Positive cut 8: Negative cut 9: Straight line 10 on which the positive cut rides: Straight line 11 with negative cut: Distance between positive cuts adjacent in the same straight line 12: Distance between negative cuts adjacent in the same straight line

Claims (9)

A cut prepreg having a plurality of cuts for dividing the reinforcing fiber in at least a partial region of the prepreg containing the reinforcing fiber and the resin oriented in one direction,
When the number of cuts included in 10 small circular regions having a diameter of 10 mm, which are arbitrarily selected from the regions, is a population, the average value of the population is 10 or more and the coefficient of variation is 20 Cut prepreg that is within%.   The cutting prepreg according to claim 1, wherein the arbitrary cutting and another cutting closest to the cutting do not divide the same reinforcing fiber.   The incision prepreg according to claim 1 or 2, wherein the incisions have substantially the same length Y, and the distance between the closest incisions is longer than 0.5 times Y.   The cutting prepreg according to any one of claims 1 to 3, wherein the cutting is inserted obliquely with respect to the orientation direction of the reinforcing fibers.   The absolute value of the angle θ formed by the incision and the orientation direction of the reinforcing fibers is substantially the same, and further, the incision in which θ is positive (called positive incision) and the incision in which θ is negative (negative incision) The cutting prepreg according to any one of claims 1 to 4, comprising:   The cutting prepreg according to claim 5, comprising substantially the same number of positive cuttings and negative cuttings.   The distance between an arbitrary cut and another closest cut existing on an extension of the cut is different in length between a positive cut and a negative cut. The cutting prepreg described in 1. A method for producing a cut prepreg having a plurality of cuts for dividing the reinforcing fiber into at least a part of the region of the prepreg containing the reinforcing fiber and the resin,
A method for manufacturing a cut prepreg, comprising: a step 1 for inserting a plurality of cuts 1 into a prepreg; and a step 2 for inserting a plurality of cuts 2 that do not overlap the cuts 1 with respect to the prepreg.   The cut prepreg according to claim 8, wherein an angle θ1 formed by the cut 1 and the reinforcing fiber is positive or negative, and an angle θ2 formed by the cut 2 and the reinforcing fiber is different from the formed angle θ1. Manufacturing method.

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