JP6057118B2 - Prepreg - Google Patents

Description

  The present invention relates to a prepreg having a matrix resin as a thermosetting resin composition used for producing a fiber-reinforced composite material molded article, and particularly suitable for the production of a large molded article with few voids due to a vacuum bag molding method. Related to prepreg.

  Conventionally, a prepreg obtained by impregnating a reinforcing fiber sheet with a thermosetting matrix resin composition has been widely used as an intermediate material for molding composite materials such as sports leisure equipment and aircraft parts such as fishing rods and golf shafts. However, in recent years, it has also been used as an intermediate material for molding composite material structural members of large-scale wind turbine blades. In forming a thick and long composite material like a structural member of a wind turbine blade, a prepreg having a relatively thick surface is used, and vacuum bag forming capable of forming a large size at low cost is often employed.

  Such a prepreg is generally laminated and cured with pressure and heating to form a composite material with few voids.However, when the number of laminated layers is large or the molding area is large, the air contained in the prepreg is originally When the prepregs are laminated, the air taken in between the layers does not discharge well out of the system at the time of pressure heating molding, and remains in the composite material molding to form voids. The appearance could be adversely affected.

  In particular, vacuum bag molding is a cheap and suitable molding method for large-scale molding, but it cannot remain above the atmospheric pressure like press molding or autoclave molding, so it remains in the layers and layers of the laminated prepreg during molding. However, it is difficult to obtain a composite material molded product with less voids, because it is difficult to discharge the air to the outside of the system.

  Various methods have been proposed in order to overcome this, but the principle common to many of them is that the surface tack of the prepreg is suppressed and air is not easily taken in between the layers at the time of lamination. Sometimes, a deaeration route was secured, and the air taken in between the layers was discharged outside the system. In a prepreg whose surface is covered with a tacky (adhesive) resin layer, air is easily taken in between the layers, and the air once taken in between the layers as shown in the schematic diagram of FIG. It is not discharged and remains in the molded product to form voids. When vacuum bag molding is performed with a weak surface tack and a degassing path secured, the air taken in between the layers of the prepreg is easily discharged out of the system and the interlayer voids remaining in the molded product are reduced. As a result, the air in the prepreg layer is also easily diffused and discharged, and as a result, the voids in the molded product are also reduced.

  Various proposals have been made so far for securing a degassing path when forming a vacuum bag. For example, in Patent Document 1, a method of attaching a deaeration base material such as a thin woven fabric or nonwoven fabric to a prepreg as a degassing route is used. In Patent Documents 2 and 3, resin is impregnated into a part of the prepreg by partial impregnation. A method is described in which a portion of only the reinforcing fibers not left is actively left and used as a degassing route. Further, in Patent Document 4, as shown in the schematic diagram of FIG. 2, a wet portion where a resin layer is held on the surface of the prepreg by surface tension at a portion where the film convex portion and the prepreg surface are in contact with each other by attaching an embossed film to the prepreg. (Described in Patent Document 4 as a resin-impregnated portion) is formed, and in the film recess where the film and the prepreg surface do not contact each other and the air layer remains, the phenomenon that the resin is absorbed by the reinforcing fiber layer, so-called resin sinking Embossed film surface so that a dry part (described as a fiber part in Patent Document 4) is formed on a part of the surface of the prepreg due to the phenomenon, the dry part and the wet part form a sea-island structure, and the dry part of the prepreg surface becomes the sea part. There has been proposed a method for securing a deaeration route to the end of the laminated body by selecting.

  However, in the method of attaching the degassing substrate as disclosed in Patent Document 1, the cost increases and the mass increases, and depending on the degassing substrate to be used, the molding machine It is also possible to adversely affect the characteristics. In addition, in partially impregnated prepregs as disclosed in Patent Documents 2 and 3, it is necessary to moderately control the degree of resin impregnation in order to form a degassing path, or a patterned matrix resin film is formed. In addition to difficulties in manufacturing methods such as the need to make, when the reinforcing fiber is carbon fiber, there is a concern that carbon fiber fly may occur during prepreg cutting or laminating work, floating in the environment and causing electrical failure Is done.

  In contrast to the prepreg or partially impregnated prepreg to which these degassing substrates are attached, the method using an embossed film described in Patent Document 4 can be easily applied to a prepreg manufactured by a normal method. A degassing path can be formed on the surface. For these reasons, a thick prepreg having an embossed film attached thereto is often used in forming a large vacuum bag such as a wind turbine blade structure member using a prepreg.

On the other hand, in a relatively thin general-purpose prepreg having a reinforcing fiber basis weight of 300 g / m ² or less used for sports applications, a release paper is lined on one side from the viewpoint of workability in a cutting process and a lamination process. FIG. 3 shows a schematic diagram of a prepreg manufacturing process. A unidirectional carbon fiber prepreg by a general hot melt method is formed by aligning a plurality of carbon fiber tows drawn from a bobbin into a sheet shape, and a thermosetting resin composition is formed. It is made by sandwiching between two coated upper and lower release papers and impregnating the fiber with a thermosetting resin composition with a heated nip roll through a preheating step. In many cases, one of the upper and lower release papers used in this step is used as a backing, without being peeled off, and wound into a roll.

In order to obtain a thick composite material molded product such as a windmill blade structural member, a prepreg having a thick basis weight such that the reinforcing fiber basis weight exceeds 400 g / m ² is used from the viewpoint of reducing the lamination cost. In such a thick prepreg, if the release paper is rolled into a roll while being lined, the rigidity and thickness of the release paper loses the flexibility as an integral sheet of the release paper and prepreg, and the distorted winding shape In severe cases, the reinforcing fibers meander. For this reason, in the case of a thick prepreg, the backing release paper is also removed, and only a soft plastic film such as polyethylene conventionally used for surface protection is disposed on one side of the prepreg and is often wound into a roll. Thick prepregs are not easily deformed like thin prepregs even if they are not lined with release paper, and do not cause much trouble in cutting and laminating processes. FIG. 4 shows a schematic diagram of a unidirectional carbon fiber prepreg manufacturing process by a hot melt method in the case where after the resin impregnation, the upper and lower release paper is removed and only the protective film is attached to the prepreg and wound on a roll.
In addition, in such a thick prepreg, a matrix resin having a lower viscosity than a general-purpose prepreg having a fiber basis weight of 300 g / m ² or less is used in order to ensure easy resin impregnation and draping property of the prepreg itself after impregnation. It is often done.

At that time, by using the embossed film as the protective film, a sea-island structure of a wet part and a dry part can be formed on the surface of the prepreg as shown in FIG. In addition, a thick-weighted prepreg employing a lower-viscosity matrix resin than a general-purpose prepreg having a fiber basis weight of 300 g / m ² or less can easily move the resin due to surface tension and easily form this sea-island structure. However, the embossed film here does not include a corrugated film that does not have a sea-island structure.

  However, a normal embossed film is an aggregate of independent convex patterns. For example, in the case of an embossed film having a rhombus pattern as shown in FIG. 5a, the convex portion of the rhombus pattern as shown in FIG. It is an aggregate of islands (convex side), but the concave part or sea part of this surface is a convex part (peak part) with a continuous rhombus border as shown in FIG. 5b-2 when viewed from the other side (concave side). Become. Therefore, after the resin impregnation as in the manufacturing process of FIG. 4, the release paper on both sides of the prepreg is removed, and when such an embossed film is placed on one side of the prepreg and wound up in a roll shape, as schematically shown in FIG. In addition, the convex portions on the front and back of the embossed film are in contact with either surface of the prepreg, and a wet portion is formed at a portion where the convex portion of the embossed film and the prepreg are in contact with each other due to the action of surface tension. The surface of one prepreg in contact with the convex side of the embossed film has a sea-island structure in which the wet portion reflecting the pattern of FIG. 5b-1 is an island portion and the dry portion is an ocean portion, and is convenient for securing a deaeration route. It can be. However, when the other surface of the prepreg has a sea-island structure in which the dry portion reflecting the pattern of FIG. 5b-2 is an island portion and the wet portion is a sea portion, and the entire surface of the prepreg is covered with a resin layer Although the tack is reduced, the surface of the prepreg is not necessarily favorable for securing a degassing route.

  For example, as shown in the pattern of FIG. 5c-1, when the island part which is a wet part is made small in order to make the dry part of the prepreg surface thick, the tack of the surface of the prepreg is further reduced and the deaeration route is more reliable. However, on the other side of the prepreg, a sea part composed of a wet part reflecting the pattern as shown in FIG. 5c-2 is formed, and it is difficult to secure a degassing path originally. The area ratio increases, the tack as a prepreg becomes stronger, and voids easily remain in the molded product.

  On the other hand, as shown in the pattern of FIG. 5d-1, when the island part consisting of the wet part is enlarged, the tack of the surface becomes stronger, so that air can be easily taken in at the time of lamination, and at the same time the deaeration path consisting of the dry part is narrow. It becomes easy to block | close and a void will remain easily in a molding. However, on the other surface of the prepreg, as shown in the pattern of FIG. 5d-2, the area of the dry portion becomes large, so that the tack of the prepreg surface is greatly reduced, making it difficult to take in air during lamination, and the resin surrounding the dry portion Since the portion becomes thinner, the surface is more easily deaerated, including a three-dimensional deaeration route with the prepreg surface attached to this surface. However, when the proportion of the dry part is large as shown in FIG. 5d-2, the emboss is easily crushed if the area of the embossed unit pattern is too large, and the dry part is formed depending on the pressure applied between the embossed film and the prepreg. In the vicinity of the center of the embossed pattern intended to be in contact with the prepreg surface, a new resin portion is formed, and the tack of the prepreg surface becomes strong.

  In the prepreg manufacturing process as shown in the schematic diagram of FIG. 4, in the prepreg in which both sides of the release paper are removed and a normal flat plastic film is applied to one side as a protective film and wound in a roll shape, almost the entire surface of both surfaces of the prepreg is resin. In order to form a vacuum bag by laminating such a prepreg, the air taken in between the layers is hardly exhausted as shown in FIG. Causes voids.

  It is possible to place two embossed films on each surface of the prepreg so that both surfaces of the prepreg have a sea-island structure where the wet part is the island part and the dry part of the sufficient area is the sea part. When the prepreg is wound in a roll shape, the cost increases and the winding layer becomes very slippery and causes a problem of winding deviation.

  In addition, by temporarily removing the protective film affixed to the surface of the prepreg and leaving it for a while, the resin layer on the surface of the prepreg can be eliminated using the resin sinking phenomenon, and the tack of the prepreg can be reduced. It is extremely disadvantageous in terms of work efficiency.

JP 2004-074741 A JP 2007-098818 A JP 2002-249605 A JP 2002-327076 A

  An object of the present invention is a relatively thick prepreg in which a reinforcing fiber sheet is impregnated with a thermosetting matrix resin composition, and an embossed film is stuck only on one side and nothing is stuck on the other side in a roll shape. The part of the prepreg that is wound substantially touches the convex bottom of either side of the embossed film, and the part that contacts the embossed film on one side of the prepreg forms a wet part, and the part that does not touch the embossed film on one side of the prepreg In the prepreg forming the part, the wet part forms the island part and the dry part forms the sea part to ensure the deaeration path on the one side of the prepreg, and the wet part forms the sea part on the other side of the prepreg. The air taken in between the prepreg layers on both sides of the prepreg can be easily formed in the prepreg laminated state By easily discharged out of the system, it is to provide an inexpensive small composite molded product having voids by vacuum bag molding.

The above problem is a prepreg roll in which a prepreg sheet impregnated with a thermosetting matrix resin composition in a reinforcing fiber sheet is wound in a roll shape, and embossed films and prepreg sheets having irregularities are alternately arranged, In the part where the convex part of the embossed film is in contact with the prepreg sheet on both sides of the prepreg sheet, the total area of the convex part on one side of the embossed film and the total area of the convex part on the other side of the embossed film is the prepreg sheet. The embossed film has an embossed sloped surface portion that does not contact any surface of the prepreg sheet, and the ratio α of the planar projected area of the embossed sloped surface portion to the area of the prepreg sheet is 50% or more. This can be solved by the prepreg roll.

  According to the present invention, a prepreg in which a reinforcing fiber sheet is impregnated with a thermosetting matrix resin composition, using a prepreg wound in a roll shape with an embossed film on one side and nothing on the other side is used. Thus, air remaining in and between prepreg layers in the vacuum bag forming process can be efficiently discharged out of the system, and a composite material molded product with less voids can be obtained.

The schematic diagram of the state by which the air was taken in between the layers of a prepreg. The schematic diagram of the wet part and dry part of the prepreg surface formed by sticking of an embossed film. The schematic diagram of the unidirectional carbon fiber prepreg manufacturing process by the general hot-melt method. The schematic diagram of the unidirectional carbon fiber prepreg manufacturing process by the hot-melt method in the case of peeling off the release paper on both sides after resin impregnation and attaching only the protective film and winding it up in a roll shape. The schematic diagram of a rhombus pattern embossed film. The schematic diagram of the example of the embossing pattern surface from which the wet part turns into an island part of a sea-island structure in the prepreg surface of an embossing film sticking surface. The schematic diagram of the example of the embossing pattern surface in which the wet part forms the sea part of a sea island structure in the prepreg surface of an embossing film sticking surface. The schematic diagram at the time of reducing the wet part which comprises the island part of a sea-island structure. The schematic diagram of the opposite surface of FIG. 5c-1. The schematic diagram at the time of enlarging the dry part which comprises the island part of a sea-island structure. The schematic diagram of the opposite surface of FIG. 5d-1. The schematic diagram which shows a mode that the wet part was formed in both surfaces of the prepreg by which the embossed film was stuck only on the one side surface, and was wound in roll shape. The schematic diagram when the prepreg wound in the roll shape by which the embossed film was stuck only on the one side surface is pulled out at the time of lamination | stacking. The schematic diagram for demonstrating a rhombus embossing pattern. The top view of a rhombus unit pattern. The schematic diagram which shows the cross section of the embossed film in the short diagonal of a rhombus pattern unit pattern. The schematic diagram for demonstrating a tortoiseshell pattern embossing pattern. The top view of a turtle shell pattern unit pattern. The schematic diagram which shows the cross section of the embossed film in the line | wire which connects the midpoint of two parallel sides of a turtle shell pattern unit pattern. The schematic diagram for demonstrating the turtle shell pattern embossing pattern especially suitable for this invention. The top view of the turtle shell unit pattern especially suitable for this invention. The schematic diagram which shows the cross section of the embossed film in the short diagonal of the turtle shell pattern unit pattern especially suitable for this invention. The schematic diagram for demonstrating a dot pattern embossing pattern. The top view of a dot pattern unit pattern. The schematic diagram which shows the cross section of the embossed film in the line | wire which connects the midpoint of two parallel sides of a dot pattern unit pattern. The bagging composition schematic diagram in the case of vacuum bag fabrication.

The present invention is a prepreg roll in which a prepreg sheet impregnated with a thermosetting matrix resin composition in a reinforcing fiber sheet is wound in a roll shape, and embossed films having concavo-convex and prepreg sheets are alternately arranged, In the part where the convex part of the embossed film is in contact with the prepreg sheet on both sides of the prepreg sheet, the total area of the convex part on one side of the embossed film and the total area of the convex part on the other side of the embossed film is the prepreg sheet. The embossed film has an embossed sloped surface portion that does not contact any surface of the prepreg sheet, and the ratio α of the planar projected area of the embossed sloped surface portion to the area of the prepreg sheet is 50% or more. It is a prepreg roll.

  The prepreg of the present invention is affixed to one side of the prepreg so that one side of the embossed film having unevenness is in contact, and the prepreg is wound in a roll shape so that the other side of the prepreg and the other side of the embossed film are in contact with each other. Since the prepreg roll is attached by the winding pressure, the surface of the prepreg is formed on one surface of the prepreg by the action of surface tension. A surface having the wet part as the sea part of the sea-island structure is formed on this surface. When the prepreg of the present invention uses a matrix resin having a lower viscosity than a general-purpose prepreg, the resin can be easily moved by surface tension, and the sea-island structure including the wet part and the dry part is relatively short. Since it is formed in time, it will be used for a lamination | stacking operation | work in the state which formed these sea island structures substantially.

  FIG. 7 shows a schematic diagram when the prepreg is drawn out from a roll obtained by sticking an embossed film to the prepreg. At this time, since the slope of the embossed film at the boundary between the bottom and the convex top surface of the embossed film shown in FIG. 6 does not touch any surface of the prepreg, the ratio of the area corresponding to this sloped portion is increased. Since the ratio of the area where the embossed film and the prepreg come into contact with each other becomes smaller, the tack of both surfaces of the prepreg can be reduced at once.

In the prepreg roll of the present invention, both sides of the embossed film are in contact with the surface of the prepreg. In the part where the prepreg is in contact with the embossed film, the resin that covers the prepreg surface layer does not soak into the prepreg, and the part where the prepreg is in contact with the embossed film occurs. A phenomenon in which the resin soaks into the prepreg occurs. When the convex surface of the embossed film (upper surface shown in the perspective views of FIGS. 8a, 9a, 10a, and 11a) faces the prepreg, the contact portion between the embossed film and the prepreg is a wet portion that forms an island portion of a sea-island structure. The area around the contact area is a dry sea area. When such a prepreg is laminated, a dry sea part acts as a deaeration route, and a molded plate obtained by molding is good without voids between layers. On the other hand, on the back side, the concave surface of the embossed film (the lower surface shown in the perspective views of FIGS. 8a, 9a, 10a, and 11a) is opposed to the prepreg surface. When the prepreg is laminated, the deaeration path may not be formed well if the dry island portion is small relative to the entire area.

When the wet part, which is the sea part that blocks the degassing path, is less than 40% of the product area of the prepreg, the present inventors can mold the degassing path without blocking and obtain a good molded product. I found. Here, the product area of the prepreg is an area obtained by projecting in a planar shape in the thickness direction of the prepreg regardless of the fine structure of the surface of the prepreg.

  The fiber base material constituting the reinforcing fiber sheet of the present invention is composed of continuous fibers, and various materials can be used according to the purpose of use of the fiber-reinforced composite material. Specific examples of the continuous fiber used in the present invention include carbon fiber, graphite fiber, aramid fiber, silicon carbide fiber, alumina fiber, boron fiber, tungsten carbide fiber, glass fiber, etc., among which carbon fiber and glass fiber are used. preferable.

  Examples of the form of the fiber substrate constituting the reinforcing fiber sheet of the present invention include a form in which continuous fibers are aligned in one direction, a woven cloth, and a form of non-crimp fabric. Among these, a form in which continuous fibers are aligned in one direction is preferable in terms of strength development.

The prepreg constituting the prepreg roll of the present invention has a fiber basis weight of preferably 400 g / m ² or more, more preferably 500 g / m ² or more, particularly 600 g / m ² from the viewpoint of reducing the lamination work of thick molding. Most preferably, it is m ² or more.

  The winding diameter of the prepreg roll of the present invention is not particularly limited. However, a thick prepreg having a high basis weight has a large winding diameter because the difference in winding circumference between the inner surface and the outer surface in the winding state is large. Specifically, the ratio of the winding diameter to the thickness of the prepreg of the present invention including the embossed film ((outer diameter) / (prepreg thickness)) is preferably 400 or more, more preferably 600 or more, and particularly preferably 800 or more. preferable. For the purpose of avoiding problems due to the circumferential difference, it is preferable that this ratio is large. However, if the ratio is too large, handling of the prepreg roll becomes difficult, so 2000 or less is preferable, and 1500 or less is more preferable.

  The prepreg of the present invention is preferably a hot melt prepreg using a thermosetting resin composition such as an epoxy resin as a matrix resin. Solvent-based prepregs are not preferred because they are difficult to remove with thick prepregs having a high basis weight, and the residual solvent volatilizes and causes formation of voids in the molding process.

<Embossed film>
As the embossed film used for the prepreg roll of the present invention, when the embossed film is sandwiched between the front and back surfaces, the total area of the portions where each flat surface and the embossed film are in contact may be equal to or less than the product area of the embossed film. is necessary. The product area of the embossed film referred to here is an area obtained by projecting in a planar shape in the thickness direction of the embossed film regardless of the structure of the embossed film.

The embossed film used for this invention is demonstrated with a schematic diagram. FIG. 8a shows a three-dimensional schematic diagram of an embossed film with a rhombus pattern as a unit, a plan view of the unit pattern is shown in FIG. 8b, and a schematic diagram of the cross section of the embossed film along its short diagonal line and a planar projection of each part The length is shown in FIG. Here, there is an inclined embossed slope between the rhombus-shaped convex portion or island portion and the concave portion (convex portion when viewed from the opposite side) or sea portion surrounding it. If the embossed pattern is not crushed, this embossed slope will not touch the prepreg on either side of the embossed film, so the larger the embossed slope, the greater the proportion of dry parts on both sides of the corresponding prepreg. Tack on both sides of the prepreg can be reduced. Moreover, even if the width of the bottom surface portion of the concave portion surrounding the rhombic convex portion (the convex portion viewed from the opposite surface) is reduced, the gap between the island portion and the island portion formed of the wet portion of the prepreg derived from the convex portion of the embossed film Since the dry portion corresponding to the slope portion is secured, the concern that the degassing path of the dry portion becomes too narrow and becomes blocked during evacuation as shown in FIG.

However, if this embossing slope is too large, there is a limit because the embossing itself may be crushed by the sticking pressure or winding pressure depending on the thickness and elastic modulus of the substrate. When crushed, the air layer disappears, the area where the embossed film comes into contact with the prepreg increases, the wet portion increases, and the tack is strengthened, which is not suitable for the purpose of the present invention.

Here, ignoring the embossing, the inclination angle of the slope and the flatness of the rhomboid island portion of the embossed film are ignored, and A (diamond short diagonal length of the convex top surface portion of the unit pattern), B ( The plane projection length on the short diagonal of the slope portion connecting the convex top surface portion of the unit pattern of the embossed film and the bottom surface portion of the concave portion (sea portion of the embossed film) surrounding the island portion, C (the sea surface of the unit pattern of the embossed film unit) The length of one side of the rhombus short diagonal) and the length A ′, B ′, C ′ of the rhombus long diagonal direction defined in the same way, the ratio of the planar projection area of the embossed slope to the corresponding prepreg area of one side α (%) is expressed by the following equation.
α = 2 (A × B ′ + A ′ × B + 2B × B ′) / ((A + 2B + 2C) × (A ′ + 2B ′ + 2C ′)) × 100 (%) (1)
On the other hand, the area ratio β with respect to the prepreg area of the embossed film sea is expressed by the following equation.
β = (2C ′ × (A + 2B) + 2C × (A ′ + 2B ′) + 4C × C ′) / ((A + 2B + 2C) × (A ′ + 2B ′ + 2C ′)) × 100 (%) (2)
Further, the area ratio γ (%) with respect to the prepreg area of the island portion of the embossed film is expressed by the following equation.
γ = A × A ′ / ((A + 2B + 2C) × (A ′ + 2B ′ + 2C ′)) × 100 (%) (3)
In the case of industrially produced rhombus patterned embossed films, many of them are A: B: C = A ′: B ′: C ′. Therefore, α, β, and γ are simplified to formulas (1) ′, ( 2) 'and (3)'.
α = 4 (A × B + B ² ) / (A + 2B + 2C) ² × 100 (%) (1) ′
β = 4C × (A + 2B + C) / (A + 2B + 2C) ² × 100 (%) (2) ′
γ = A ² / (A + 2B + 2C) ² × 100 (%) (3) ′
Many of the long and short angle ratios are in the range of 1.0 to 3.0 (square pattern when 1.0), but is irrelevant to the above area ratio formula.

Similarly, an example of an embossed film having a regular hexagonal turtle shell pattern is shown in FIGS. 9a, 9b, and 9c. In this case, as shown in FIGS. 9b and 9c, α, β, and γ are expressed by the same expressions (1) ′ to (3) ′ as the rhombus pattern when the lengths of A, B, and C are taken.
As described above, the diamond pattern and the regular hexagonal turtle shell pattern have been described as representative examples, but the pattern of the embossed film can be arbitrarily selected so as to meet the object of the present invention.
For example, as a modification of the diamond pattern, FIG. 11a, FIG. 11b (the outline of the unit is shown as a square) having one truncated cone in each diamond-shaped unit pattern, the one shown in FIG. 11c (dot pattern), It is conceivable that the pattern is composed of equilateral triangle unit patterns, the center of the outer shape of the unit pattern does not coincide with the center of the convex top surface portion, or the like.
The embossed film pattern used in the present invention includes a pattern in which one unit pattern has two or more convex top surface portions in addition to a pattern in which one unit pattern has one convex top surface portion.

The pattern of the embossed film that can be used for the prepreg roll of the present invention may be arbitrary, but when the embossed structure is crushed by the pressure applied to the prepreg or the winding pressure when wound in a roll shape, the film surface and the prepreg surface come into contact with each other. The area increases and a wet part is newly formed on the surface of the prepreg, so that tack cannot be suppressed. However, if you choose too thick or embossed film base material to increase the crushing strength of the embossed film, sticking it to the prepreg and winding it into a roll shape will distort the wound shape, The drapability of the prepreg with the embossed film is lowered and the laminating workability is also deteriorated. Moreover, when the base material of an embossed film is too thin, not only is an embossed structure easily crushed, but it is easily broken in a prepreg manufacturing process or a laminating process. As a result of various studies by the present inventors based on these, the Young's modulus of the base material of the embossed film suitable for the present invention is preferably 0.3 to 1.5 GPA, and the thickness of the base material of the embossed film is It is preferable that it is 40-140 micrometers. In view of industrial versatility, an embossed film based on a CPP (Cast Polypropylene) film or an HDPE (High Density Polyethylene) film is preferable.

Furthermore, it is naturally limited to reduce the angle of inclination of the embossed slope and increase the horizontal projection area of the slope, depending on the Young's modulus, thickness, and embossed pattern of the substrate. It cannot be larger than a certain level. Therefore, the size of the embossed pattern unit size is also limited in order to secure the crushing strength and to make the ratio of the horizontal projection area of the embossed slope surface portion more than a certain value. However, if the unit size is too small, the wet part formed on the surface of the prepreg is likely to be connected, the tack becomes strong, and the deaeration path is also blocked, which is not preferable.

Considering them, in order to increase the ratio α of the planar projection area of the embossed slope surface portion to 50% or more, the area of the outer shape of the unit pattern of the embossed pattern is preferably 0.1 to 9.0 mm ² . More preferably, it is 5 to 5.0 mm ² . According to the study by the present inventors, the unit size as shown in FIGS. 10a, 10b and 10c is small, and the embossed pattern is preferably a rhombus pattern or a square pattern. preferable.

Example 1
Bisphenol A type liquid epoxy resin (epoxy equivalent 189 g / eq, manufactured by Mitsubishi Chemical Corporation, product name: jER828) 40 parts by mass, bisphenol A type solid epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name: jER-1002) 60 masses As a matrix resin, 5 parts by mass of dicyandiamide (manufactured by Mitsubishi Chemical Co., Ltd., product name: jER Cure DICY) as a curing agent and 5 parts by mass of DCMU (dichlorophenyldimethylurea) as a curing aid are used as a matrix resin. Using a carbon fiber (manufactured by Mitsubishi Rayon Co., Ltd., product name: TRW40-50L), a prepreg having a fiber basis weight of 600 g / m ² and a resin mass content of 33.0% by mass is illustrated by the prepreg manufacturing apparatus illustrated in FIG. Was made. A regular hexagonal turtle shell pattern (A = 0.59mm, B = 0.31mm, C = 0.08mm, α = 59%, β = 22%) and a CPP embossed film (base material thickness 60 μm) are unit patterns on this prepreg. A regular hexagonal frustum base was attached so that the convex top surface portion was in contact with the prepreg surface, and was wound on a paper tube having a diameter of 300 mm for a length of 100 m at a winding tension of 30.0 N / m, and a prepreg roll was obtained for evaluation. . In addition, the surface to which the embossed film was affixed was used as the front (front) surface of the prepreg.

The obtained prepreg is unrolled and laminated, and the embossed film is peeled off to create a unidirectional laminate of width 300 mm x length 1000 mm x 25 ply, and vacuum bag molding with a bagging configuration as shown in FIG. Went.
At this time, when a part of the prepreg was observed with a magnifying glass (magnification 6 times), the embossing was not crushed, and the surface of the prepreg to which the embossed film was first attached was a regular hexagon corresponding to the convex top surface portion of the embossing, A wet portion where the resin was held on the surface layer of the prepreg was observed, and a wet portion was observed on the opposite surface (back surface) in a regular hexagonal border shape corresponding to the concave bottom portion of the emboss. When the prepreg front and back tacks were examined by hand, the tackiness was not strong and was a good tack. The unwinding state from the paper tube was good. The embossing film was a little sticky, but there was no problem in workability.

The unidirectional laminate obtained by vacuum bag molding is cut with a diamond blade cutter at the center and 100 mm from both ends, and after polishing, void evaluation is performed by visual observation and full-section observation with a loupe (excluding the end 10 mm) went.
As a result, no voids were observed with the naked eye, and no voids as large as several tens of μm as observed with a magnifying glass were observed, and 10 spots were observed at random per cross section with an optical microscope (100 times). Although it went, it was a favorable cross section regarding a void to the extent that several very small voids (size of a dozen μm at the maximum) were scattered. The evaluation results are summarized in Table 1.

(Other examples and comparative examples)
Implementation of the present invention in which various embossed films were pasted in place of the turtle shell pattern CPP embossed film used in Example 1 and the prepreg was wound into a roll, and a similar laminate was formed by vacuum back molding and then observed for voids. Examples and comparative examples are shown in Table 1. In all examples, the convex side of the embossed film was attached to the prepreg side.

(Example 2)
Table 1 shows a turtle shell pattern (A = 0.44 mm, B = 0.47 mm, C = 0.14 mm, α = 62%, β = 31%) as an embossed film made of HDPE (substrate thickness 70 μm). Examples of the invention are shown.

Example 3
Table 1 shows a turtle shell pattern (A = 0.40 mm, B = 0.38 mm, C = 0.10 mm, α = 64%, β = 27%) CPP embossed film (base material thickness 35 μm) Examples of the invention are shown. When the embossed film was peeled off from the prepreg, the degree of sticking was somewhat strong, and the embossed film was felt to be stretched, but there was no problem in workability.

Example 4
Table 1 shows a rhombus pattern (A = 0.35 mm, B = 0.18 mm, C = 0.06 mm, α = 55%, β = 27%) HDPE embossed film (base material thickness 60 μm) Examples of the invention are shown. Although the tack on both sides of the prepreg was generally suppressed, a part of the embossed film was crushed, and the trace of the embossed film on the back of the prepreg was observed. The number of voids in the molded product was slightly better than the other examples, and was almost satisfactory.

(Comparative Example 1)
Table 1 shows a turtle shell pattern (A = 0.80 mm, B = 0.23 mm, C = 0.20 mm, α = 34%, β = 42%) HDPE embossed film (base material thickness 60 μm) The comparative example of invention is shown. α was out of the scope of the present invention, the tack on the front surface was strong, and the tack on the back surface was slightly strong. The embossing film was sticky and the workability was poor. Some voids in the molded product exceeded 100 μm.

(Comparative Example 2)
Table 1 shows a rhombus pattern (A = 1.50 mm, B = 0.09 mm, C = 0.05 mm, α = 18%, β = 11%) LDPE embossed film (substrate thickness 130 μm) The comparative example of invention is shown. α is out of the scope of the present invention, the surface tack is very strong, the embossing film sticking is very strong and difficult to peel off, and the workability is poor. Large voids exceeding several hundred μm were also found in the molded product.

(Comparative Example 3)
Table 1 shows a diamond pattern (A = 1.00mm, B = 0.09mm, C = 0.17mm, α = 17%, β = 40%) LDPE embossed film (base material thickness 130 μm) The comparative example of invention is shown. The surface tack was strong and the back tack was also slightly strong. Some voids in the molding exceeded several hundred μm.

(Comparative Example 4)
Table 1 shows a rhombus pattern (A = 1.50 mm, B = 0.10 mm, C = 0.10 mm, α = 18%, β = 20%) LDPE embossed film (base material thickness 70 μm) The comparative example of invention is shown. The surface resin part has a strong tack on the surface that forms the island part, and many embossed crushes are observed, and the surface resin part has a strong tack on the surface that forms the sea part, and the voids in the molded product are several hundred μm. Something was exceeded.

(Comparative Example 6)
Table 1 shows a dot pattern (A = 0.46mm, B = 0.20mm, C = 0.31mm, α = 38%, β = 47%) as an LDPE embossed film (substrate thickness 130 μm). The comparative example of invention is shown. The surface resin part has a very strong tack on the surface forming the sea part, and there are some voids in the molded product exceeding several hundred μm.

  According to the present invention, in a vacuum bag molding using a thick prepreg having a large fiber basis weight impregnated with a thermosetting matrix resin, a good composite material molded product with few voids can be obtained at a low cost even though it is thick and long. be able to.

1 ... prepreg layer (1 ply),
2 ... resin layer on the surface of the prepreg,
3 ... Air taken in between layers of the prepreg when the prepreg is laminated,
4 ... Air left in the prepreg layer during resin impregnation in the prepreg manufacturing process,
5 ... prepreg,
6 ... backing release paper,
7 ... Embossed film,
8: Embossed film concave side convex part,
9 ... Embossed film convex top surface part 10 ·· Prepreg surface layer dry part,
Prepreg surface layer dry part on the opposite side of 10 'prepreg,
11. The wet part where the prepreg surface layer is covered with resin,
11 '-wet part where the prepreg surface layer on the opposite side of the prepreg is covered with resin,
12. Embossing slope part,
12 ′ ・ Horizontal projection part of embossed slope,
13. Carbon fiber bobbin,
14. Carbon fiber tow,
15. Bar for opening,
16. Pre-nip roll,
17 .. Resin composition coated release paper,
18. Preheated plate heater,
19. Heating nip roll for impregnation,
20 ・ ・ Traction nip roll,
21 .. Release paper take-up shaft,
22..Prepreg with release paper,
23. Pre-preg roll
24 .. Prepreg without release paper,
25..Protective film,
26 .. Prepreg with protective film,
27 ... Example of embossed film with rhombus pattern,
28. ・ Rhombus embossed pattern convex top surface or island,
29 .. Convex side convex part or sea part of rhombus embossed pattern,
30 ... Rolls of prepreg with diamond-shaped embossed film,
31. Prepreg,
The figure which looked 32 ... 31 inside out,
33 .. Embossed film with rhombus pattern,
34 .. Projection surface of rhombus pattern,
35. ・ Rhombic pattern edge convex surface,
36 .. The prepreg surface in which the wet part of the surface layer of the prepreg covered with resin constitutes the island part of the sea-island structure,
37 .. The prepreg surface in which the wet part of the prepreg surface layer covered with resin constitutes the sea part of the sea-island structure,
38 .. Convex top surface or island of embossed film
39. Embossing slope,
40 .. Embossed film concave side convex part or sea part,
41 .. Prepreg laminate,
42 .. Release film,
43. Base plate,
44. ・ Surface breather,
45. Bagging film,
46. Edge breather,
47..Glass yarn,
48. Sealant

Claims (6)

A prepreg roll in which a prepreg sheet impregnated with a thermosetting matrix resin composition in a reinforcing fiber sheet is wound in a roll shape,
Embossed film with unevenness and prepreg sheet are alternately arranged,
In the part where the convex part of the embossed film is in contact with the prepreg sheet on both sides of the prepreg sheet, the total area of the convex part on one side of the embossed film and the total area of the convex part on the other side of the embossed film is the prepreg sheet. with is the product area of the following,
This embossed film has an embossed slope portion not in contact with any surface of the prepreg sheet, and the ratio α of the planar projection area of the embossed slope portion to the area of the prepreg sheet is 50% or more .   The prepreg roll according to claim 1, wherein the embossed film has a sea-island structure in which a convex portion on one surface of the embossed film is an island.   The prepreg roll according to claim 2, wherein the embossed film has a sea-island structure in which a convex portion on the other surface of the embossed film becomes the sea.   The prepreg roll according to any one of claims 1 to 3, wherein a total area of convex portions on one surface of the embossed film is less than 40% of a product area of the prepreg sheet.   The prepreg roll according to any one of claims 1 to 4, wherein a total area of convex portions on the other surface of the embossed film is less than 40% of a product area of the prepreg sheet. The one product area of the prepreg of the protrusions per unit surface of the embossing film, the prepreg roll according to any one of claims 2 to 5 is 0.1~9.0mm ^2.