JP2012111957A - Prepreg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a prepreg which generates no void caused by trapping of air in an interlayer when the prepregs are laminated to produce a molded article, has excellent handleability as well, and can produce molded articles having any complicated shapes.SOLUTION: The prepreg is obtained by impregnating a reinforcing fiber sheet with a matrix resin. In the prepreg, a continuous resin layer is present in the inside, and at least one side surface is composed of a resin-impregnated part in which the impregnating resin is substantially present and a fiber part in which the impregnating resin is not substantially present.

Description

  The present invention relates to a prepreg used for producing a fiber-reinforced composite molded product, and particularly to a prepreg suitably used for vacuum bagging.

  In order to maintain the shape of a prepreg, a prepreg used for producing a fiber reinforced composite molded article is generally held on one side by a release paper coated with silicone. The other surface is covered with a protective film such as a polyethylene film in order to hold the tack of the prepreg or to prevent foreign matters such as dust from adhering.

  However, by covering one or both sides of the prepreg with a sheet-like material such as release paper or protective film, the resin contained in the prepreg shifts to the sheet-like side due to the interaction with the sheet-like material such as surface tension. In addition, both surfaces of the prepreg become resin-rich.

  In this way, the prepreg whose both surfaces are resin-rich can be processed into the desired composite molded product. It remains resin rich. If a plurality of prepregs having a resin-rich surface are simply laminated, air is trapped between the two prepregs. When the prepreg is cured in a state where air is trapped between the prepregs in this way, the obtained molded product loses its integrity. Alternatively, the trapped air traces become voids, and the voids become a stress concentration portion under a certain stress, so that the function of the composite molded product is lowered, and the function is impaired.

  In order to avoid such inconvenience, it is necessary to eliminate trapping of air between the laminated prepregs. For example, using an auto layup machine, there is a method of laminating prepregs while pressing them together while pressing and heating, and laminating while evacuating the air between the prepregs. Since it is expensive, it also affects the price of the composite molding obtained. In addition, since the auto layup machine is not suitable for use in the case of stacking in a complicated shape, its use is limited. For these reasons, the actual situation is that the prepreg lamination work is still performed manually by the operator.

  For this reason, a method has been proposed in which talc is adhered to the surface of the prepreg to prevent the resins on the surface of the prepreg from directly sticking to each other in a planar manner, thereby reducing the stickiness of the resin itself and preventing air trapping. This method of attaching talc is effective in reducing the tackiness of the prepreg, but it merely reduces the tackiness, and talc is contained in the molded product, so that a large molding is required. When manufacturing a product, an inadvertent increase in weight is caused. In consideration of the mechanical properties of the molded product, it is desirable that talc be uniformly attached, but talc may be localized due to spotting, in which case the mechanical property of the molded product may be reduced. There is also.

Alternatively, papers published at the 31st International SAMPE Symposium (held April 7-10, 1986) and 32nd (held April 6-9, 1987) ("Production of void free composite parts without debulking") "," Degree of impregnation of prepregs-
The method for preventing interlayer voids disclosed in “Effects on prosity”) employs a prepreg in which the entire surface of the reinforcing fiber sheet is not impregnated with resin but is impregnated with resin on one side of the reinforcing fiber sheet. ing. The prepreg in which this resin is impregnated on the surface of one side is formed with a flow path for releasing trapped air and volatiles between the layers when a plurality of prepregs are laminated. It is said that it can be prevented.

  This prepreg, in which the resin is impregnated on one side of the reinforcing fiber sheet, has a reinforcing fiber sheet interposed between a release paper coated with a pre-weighed resin and a release paper not coated with a resin. It is manufactured by a method of sandwiching and pressing this from both sides.

  Alternatively, in the method disclosed in Japanese Patent Application Laid-Open No. 2-227212, a large number of grooves along the molding direction of the prepreg are formed on the surface of the prepreg sufficiently impregnated with the resin by a roller having an uneven portion in the circumferential direction. Is forming. When forming a plurality of the prepregs by laminating a plurality of the prepregs with the direction of the concave grooves and forming by vacuum bagging, the concave grooves on the surface of the prepreg function as a passage for releasing air trapped between layers and volatiles, Interlayer voids can be prevented.

JP-A-2-227212

  However, in the prepreg manufactured by the above-mentioned double film method in which the resin is unevenly distributed on one surface, the release paper not coated with the resin is peeled off and the prepreg and the resin for supporting the prepreg are applied. It is necessary to use it in the state of a prepreg material made of a release paper. At this time, since the release paper not coated with resin is in direct contact with the reinforcing fibers, when the release paper is peeled off, the single yarn is pulled out from the reinforcing fiber sheet, and the single yarns that have been pulled out one after another And other single yarns are entangled, and finally there is an inconvenience that an opening is formed in that part, which may cause an important defect as a product.

  In addition, since there is no resin on one side surface, when the surfaces with no resin on the surface are laminated to face each other, the layers cannot be laminated by adhering to each other, and the prepreg is easy to handle. descend.

  On the other hand, in the method of forming a groove on the prepreg surface disclosed in JP-A-2-227212, when the upper and lower layers are laminated so as to intersect each other, the shape of the groove is The groove is maintained, and the concave groove becomes an air flow path so that trapped air can flow, and a void-free molded body is obtained. However, when the upper and lower layers are laminated so that the respective grooves are substantially parallel, the grooves on the surface of the prepreg are likely to be blocked by the material on the back side of the prepreg laminated thereon, and conversely the air Since it is trapped, voids are easily formed.

  The present invention has been made to solve such conventional problems, and when manufacturing a molded product by laminating prepregs, air is not trapped between the layers of the prepregs, and voids are not generated. It is an object of the present invention to provide a prepreg that can produce a molded article having any complicated shape.

Means and effects for solving the problems

In order to solve the above-mentioned problem, the invention according to claim 1 is a prepreg in which a reinforcing fiber sheet is impregnated with a matrix resin, wherein a continuous resin layer is present, and at least one surface is substantially It is characterized by comprising a resin-impregnated portion where the impregnated resin is present and a fiber portion where the impregnated resin is not substantially present.
The reinforcing fiber sheet refers to a sheet in which reinforcing fibers such as carbon fiber and glass fiber are aligned in one direction, a reinforcing fiber woven or knitted fabric, or a nonwoven fabric.

  In the prepreg of the present invention, since a fiber portion substantially free of impregnating resin is formed on at least one side surface, a plurality of the prepregs can be used without using an expensive apparatus such as an auto layup machine. Forming with desired mechanical strength without causing voids between layers even when laminated by hand without debulking and cured by conventional methods such as vacuum bagging You can get things.

  This is because the fiber portion on one side surface of the prepreg becomes an escape route for air trapped between layers during lamination and volatiles during molding during curing molding. In addition, at the time of molding, the surrounding resin flows into the fiber portion and is filled with the resin until the resin is completely cured at the time of molding.

  Further, since the resin impregnated portion where the resin is sufficiently impregnated and substantially impregnated resin is present is formed on the one side surface, the adhesion between the upper and lower layers at the time of lamination can be appropriately obtained, and the prepreg The handleability is improved.

The invention according to claim 2 is characterized in that the one-side surface has a sea-island shape in which the fiber portion constitutes a sea portion and the resin-impregnated portion constitutes an island portion.
Thus, by using the fiber portion as the sea portion and the resin-impregnated portion as the island portion, air and volatiles trapped between the layers can be efficiently and effectively released to the outside.

The invention according to claim 3 is characterized in that the area of the island portion is 1 to 80% with respect to the total area of the one-side surface. Furthermore, the area of the island part is preferably 2 to 50% with respect to the total area of the one-side surface.
When the area of the island portion is less than 1% with respect to the total area of the one-side surface, the adhesion between the upper and lower layers at the time of lamination is insufficient, and handling of the prepreg may be difficult. Further, when the area of the island portion is more than 80% with respect to the total area of the one-side surface, the fiber portion is immediately blocked by the flow of the surrounding resin at the time of molding, and the air trapped between the layers In addition, the volatiles cannot be completely released to the outside, and the remaining air may become voids inside the molded body.

The invention according to claim 4 is characterized in that the distance between the centers of the adjacent island portions is 1 to 10 mm. Furthermore, the distance between the centers is preferably 2 to 5 mm.
By forming the island portion so that the distance between the centers of the island portions is in the above range, air and volatiles trapped between the layers can be more smoothly and completely released to the outside.

  In order to produce such a prepreg according to the present invention, a reinforcing fiber sheet is impregnated with a matrix resin so as to form at least a continuous resin layer, and the reinforcing fiber impregnated with the matrix resin is used. It is good to include sticking the said uneven surface of the protective film which has an uneven surface toward the said reinforced fiber sheet to the at least one side surface of a sheet | seat. Furthermore, it is preferable that only the convex portion of the concave and convex surface is brought into contact with the reinforcing fiber sheet impregnated with the matrix resin.

  The material of the reinforcing fiber that can be used in the present invention is not particularly limited, and examples of the reinforcing fiber include carbon fiber, glass fiber, aramid fiber, boron fiber, and steel fiber. Among these, carbon fibers are preferably used because of their good mechanical properties after molding. As the carbon fiber, any of polyacrylonitrile (PAN) -based carbon fiber and pitch-based carbon fiber can be used.

  The reinforcing fiber sheet used in the present invention is not particularly limited, such as the form and arrangement of the reinforcing fibers. Examples of the reinforcing fiber sheet include sheets in which long fibers are aligned in one direction, and cloth (woven fabric), tow, mat, knit, and sleeve.

  Further, the material of the protective film is not particularly limited, and can be appropriately changed according to the kind of the matrix resin in consideration of the adhesion with the matrix resin. For example, a polyethylene film that has been conventionally used as a protective film can be used.

  Further, the matrix resin is not particularly limited. The resin used in the present invention is preferably a thermosetting resin, such as an epoxy resin, a polyester resin, a vinyl ester resin, a phenol resin, a maleimide resin, a polyimide resin, or a combination of a cyanate ester and a bismaleimide resin. BT resin manufactured by Co., Ltd. can be raised, and it is preferable to use an epoxy resin.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, fluorene type epoxy resin, or a combination thereof. Resins etc. are preferably used.

  Furthermore, a trifunctional or higher polyfunctional epoxy resin can also be used. Examples of the polyfunctional epoxy resin include phenol novolac type epoxy resin, cresol type epoxy resin, glycidylamine type epoxy resin such as tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidylamine, and tetrakis (glycidyloxyphenyl) ethane. Glycidyl ether type epoxy resins such as tris (glycidyloxymethane) or combinations thereof are preferably used.

  It is preferable to add a curing agent to the matrix resin of the present invention. Examples of the curing agent include aromatic amines such as diphenylmethane and diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, dicyandiamide, tetramethylguanidine, thiourea addition amine, and carboxylic acid anhydrides such as methylhexahydrophthalic anhydride. Carboxylic acid hydrazide, carboxylic acid amide, polyphenol compound, novolac resin, polymercaptan, Lewis acid complex such as boron trifluoride ethylamine complex, and the like.

Moreover, those obtained by encapsulating these curing agents can also be suitably used in order to increase the storage stability of the prepreg.
These curing agents can be combined with an appropriate curing accelerator in order to increase the curing activity. Preferable examples include a combination of dicyandiamide with a urea derivative or imidazole derivative such as 3- (3,4-dichlorophenyl) -1,1, dimethylurea (DCMU) as a curing accelerator, a carboxylic acid anhydride or a novolak resin. Examples include combining triamines as curing accelerators.

  These epoxy resins and curing agents, or those obtained by pre-reacting some of them, can also be blended in the matrix resin composition. This method may be effective for adjusting viscosity and improving storage stability.

Furthermore, in addition to the constituent elements of the matrix resin described above, a thermoplastic resin may be blended for the purpose of control of resin viscosity and control of prepreg handling. In that case, the resin is selected in consideration of compatibility with the epoxy resin and not adversely affecting the physical properties of the composite material. Preferable examples include polyvinyl formal, polyvinyl butyral, polyethylene oxide, polymethyl methacrylate, polyamide, polyester, polyethersulfone, polysulfone, polyetherimide, and polyimido. Two or more kinds of these resins may be mixed.

  Further, rubber particles, soluble rubber, core-shell structure rubber, and the like can be contained as additives. These are at least partially dissolved in the base resin, or exist in the form of particles without being dissolved, but in the present invention, in order to obtain a prepreg of good quality, when present in the form of particles, substantially It is preferable to pulverize or dissolve the particles in advance so that particles having a diameter of about 50 μm or more are not included.

  In the above manufacturing method, first, the reinforcing fiber sheet is impregnated with a matrix resin by a conventional method. For example, a matrix resin is uniformly applied to the surface of the release paper, and a reinforcing fiber sheet is attached to the resin surface to impregnate the resin. The prepreg produced by this method is impregnated with the matrix resin biased to the surface of one side of the reinforcing fiber sheet, that is, the release paper side.

  Alternatively, the reinforcing fiber sheet can be impregnated with resin by sandwiching it from both sides of the reinforcing fiber sheet with a release paper having a matrix resin uniformly applied to the surface. In the prepreg obtained by this method, the resin is uniformly impregnated throughout the prepreg. When the reinforcing fiber sheet is impregnated with resin by these conventional methods, at least a continuous resin layer is formed.

  Next, the concavo-convex surface of the protective film having the concavo-convex surface is attached to at least one surface of these prepregs. For example, when the release paper is stuck only on one side, it is preferable to stick a protective film on the other side where the fiber is rich. Moreover, when the release paper is affixed on both surfaces, the release paper of at least one side is peeled off, and the said protective film is affixed on the surface.

  The protective film has a convex portion in close contact with the reinforcing fiber sheet impregnated with resin, and the concave portion is in a state separated from the sheet. At this time, in the portion where the convex portion of the protective film is in close contact, the resin impregnated in the reinforcing fiber sheet is attracted to the protective film side by surface tension, the portion becomes resin rich, and the impregnated resin is substantially Existing resin impregnated portions are formed. On the other hand, the portion corresponding to the concave portion of the protective film is separated from the reinforcing fiber sheet impregnated with the resin, so the surface tension does not act, and the resin moves to the convex portion side or to the inside of the prepreg. For this reason, the portion corresponding to the concave portion is a fiber portion substantially free of impregnating resin.

  In such a prepreg manufacturing method, when the prepreg is stored and transported, the protective film usually attached to the surface thereof is changed to a film having an uneven surface as described above. It is possible to easily produce an excellent prepreg that does not generate voids during molding consisting of an impregnated part and a fiber part, and there is no need for a particularly large device, which may affect the production cost. Absent.

  In the production method of the present invention using the contact with the concavo-convex surface of the protective film and the surface tension of the resin, the expression of the sea-island structure consisting of the resin-impregnated portion and the fiber portion on the prepreg surface depends on the viscosity of the resin. It is a phenomenon over time.

Therefore, it is preferable to maintain the viscosity of the matrix resin at 10000 Poise or lower for 4 hours or more in a state where the protective film is attached to the reinforcing fiber sheet. Or in the state which stuck the said protective film to the said reinforced fiber sheet | seat, 30 to 15 hours or more
It preferably includes holding at 0 ° C. As described above, when the impregnated resin is made to have a predetermined viscosity or less, or at a predetermined temperature for 4 hours or more, a sufficient amount of the resin moves to the surface in contact with the convex portion, and the resin-impregnated portion And the fiber part are clearly formed.

  Generally, the viscosity of the resin is lowered by increasing the temperature to be maintained. Although the resin viscosity varies depending on the matrix resin, it is generally preferable that the temperature maintained is 30 ° C. or higher. In addition, if the temperature is too high, the resin curing reaction proceeds and sufficient time for the resin to move cannot be secured, or when the prepreg is stored at room temperature later, the tackiness of the prepreg may be impaired. The holding temperature is preferably 150 ° C. or lower.

It is preferable that the concavo-convex surface of the protective film has a large number of protrusions formed independently of each other.
By using such a protective film having an uneven surface, a prepreg having a surface in which the resin-impregnated portion constitutes an island portion and the fiber portion constitutes a sea portion can be produced.

Furthermore, it is preferable that the concavo-convex surface of the protective film has a large number of convex portions uniformly distributed on the film surface.
Thus, the convex part is disperse | distributing uniformly, and the resin impregnation part exists uniformly with respect to the fiber part on the surface of the obtained prepreg. A molded product molded from such a prepreg has a uniform resin density and fiber density. In addition, although the said convex part is desirable to disperse | distribute uniformly for the reason mentioned above, of course, the said convex part may be disperse | distributed nonuniformly.

1 is a plan view of a prepreg according to a preferred embodiment of the present invention. It is arrow sectional drawing along the II line | wire of FIG. It is explanatory drawing which shows a bagging method. It is a graph which shows hardening conditions. It is a graph which shows hardening conditions. It is a graph which shows hardening conditions.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a plan view of a prepreg according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II in FIG.

  The prepreg 1 includes a reinforcing fiber sheet 2 and a matrix resin 3 impregnated in the sheet 2. As the reinforcing fiber sheet, for example, a sheet in which reinforcing fibers such as carbon fibers and glass fibers are aligned in one direction, a woven or knitted fabric of reinforcing fibers, and a nonwoven fabric can be used.

  The prepreg 1 is impregnated with a matrix resin 3 biased toward the back side, and a continuous resin layer 3a exists inside. Further, the surface is sufficiently impregnated with resin in the reinforcing fiber sheet, the resin-impregnated portion 3b where the impregnated resin is substantially present, and the fiber portion 2a where the resin is not substantially present and the reinforcing fibers are exposed. It is comprised by.

The fiber portion 2a has a sea portion, and the resin-impregnated portion 3b has a sea-island shape constituting an island portion, and the resin-impregnated portion 3b exists independently. In this embodiment, the surface shape of the resin-impregnated portion 3b has a rhombus shape and is regularly arranged in an arrow shape at regular intervals. The distance between the centers of the resin impregnated portions 3b adjacent to each other is preferably 1 to 10 mm. Furthermore, the area of the resin-impregnated portion 3b which is the island portion is preferably 1 to 80% with respect to the total surface area. The design and arrangement of the resin-impregnated portions 3b can be changed as appropriate according to the fluidity and tackiness of the resin.

  In order to manufacture a prepreg having such a configuration, first, a matrix resin is impregnated on one side of a reinforcing fiber sheet so as to form at least a continuous resin layer. For example, a predetermined amount of matrix resin is applied to the surface of the release paper, and after supplying a reinforcing fiber sheet to the surface, the reinforcing fiber sheet is impregnated with resin by means such as passing a pressing roll, It is possible to obtain a prepreg in which the resin is impregnated unevenly. Alternatively, a prepreg in which the entire reinforcing fiber sheet is impregnated with the resin can be obtained by, for example, passing a pressing roll after sandwiching the front and back of the reinforcing fiber sheet with a release paper coated with a predetermined amount of matrix resin.

  Thus, in the case of a prepreg in which the resin is biased and impregnated at least on one side of the prepreg having at least a continuous resin layer inside, for example, the other side opposite to the side on which the resin is biased and impregnated. On the surface side, the uneven surface of the protective film having an uneven surface is attached to the reinforcing fiber sheet. At this time, only the convex part of the uneven surface of the protective film is in close contact with the reinforcing fiber sheet.

  In the state where the protective film is attached to the reinforcing fiber sheet impregnated with the resin, the viscosity of the resin is set to 1000 Poise or less for 4 hours or more, or by holding at a temperature of 30 to 60 ° C. for 4 hours or more, In the reinforcing fiber sheet, the resin inside moves to the surface side by the surface tension at the portion where the convex portion of the protective film is in close contact. As a result, as shown in FIG. 1, the surface of the reinforcing fiber sheet 2 becomes a resin-impregnated portion 3b where the resin is sufficiently impregnated and substantially impregnated resin is present at the portion where the convex portion is in close contact, In a portion corresponding to the concave portion of the protective film to which the protective film is not in close contact, the fiber portion 2a is substantially free of resin.

  Such movement of the resin due to the surface tension can be seen even in a reinforced fiber sheet in which the resin is entirely impregnated and the resin is substantially present on the entire surface. When a protective film having a concavo-convex surface is pasted on the entire surface where the resin is present, the reinforcing fiber sheet moves to the part where the convex part of the protective film is in close contact, The portion where the projections are in close contact becomes a resin-impregnated portion where the resin is sufficiently impregnated and substantially impregnated resin is present, and the periphery thereof is a fiber portion substantially free of resin.

  As the protective film, it is preferable to use a polyethylene film that has been conventionally used as a protective film. However, in consideration of adhesion to the matrix resin, the protective film may be appropriately changed depending on the type of the matrix resin. Is possible.

  It is preferable that at least one surface of the protective film is an uneven surface, and in particular, the convex portions are island-like in the concave portions that are sea portions, and the respective convex portions exist independently. Furthermore, it is preferable that the convex portions are arranged uniformly and regularly.

  Moreover, it is preferable that the area of the convex part with respect to the total area of the said protective film is 1 to 80%, and the area of the convex part is 4 to 50%. Moreover, it is preferable that the distance between centers of adjacent convex parts is 1 to 10 mm, and further, the distance is 2 to 5 mm.

Hereinafter, specific examples and comparative examples of the present invention will be described.
In the following examples, an embossed film made of polyethylene having an uneven surface on its surface is used as a protective film having an uneven surface. In the concavo-convex pattern of the embossed film, diamond-shaped convex portions having a diagonal length of 4 mm × 2 mm are arranged in an arrow shape with an interval of 0.5 mm.

Example 1
An epoxy resin composition was prepared with the composition A shown in Table 1. This resin was uniformly applied onto release paper so that the resin basis weight was 108 g / m ² to prepare a resin film. The reinforcing fiber sheet is a sheet-like material in which carbon fiber manufactured by Mitsubishi Rayon Co., Ltd., TR30S (tensile elastic modulus: 235 GPa) is aligned in one direction. A unidirectional prepreg having a carbon fiber basis weight (hereinafter referred to as “FAW”) of 200 g / m ² and a resin content (hereinafter referred to as “RC”) of 35% is formed by the resin film and the reinforcing fiber sheet. did.

The concavo-convex surface of the embossed film was attached to the surface side of the prepreg so as to face the prepreg side, and held in an 80 ° C. atmosphere for 4 hours.
In the obtained prepreg, the resin penetrated into the prepreg at the portion corresponding to the concave portion of the embossed film on the surface, and the prepreg surface was a fiber portion substantially free of the resin. Moreover, in the site | part corresponded to the convex part of an embossing film, resin was fully impregnated, and it was a resin-impregnated part where the impregnation resin exists substantially. It was confirmed that such a prepreg has a sufficient tack property for performing a laminating operation.

  The prepreg stack 4 obtained by laminating 8 sheets in the direction of [−45 ° / 90 ° / + 45 ° / 0 ° / 0 ° / + 45 ° / 90 ° / −45 °] using the prepreg. As shown in FIG. 3, a release film 5 made of a copolymer of tetrafluoroethylene and ethylene is disposed and laminated on both sides. This laminate is placed on a base plate 6 made of a 5 mm thin aluminum plate coated with a release agent. Further, a surface breather 7 made of glass fiber fabric and a bagging film 8 made of nylon were sequentially laminated on the upper surface of the laminate and bagged, and then cured under the conditions shown in FIG.

  Here, the periphery of the releasable film 5 disposed on both surfaces of the prepreg stack 4 is sealed with a high viscosity resin except for a part thereof. An edge breather 9 made of glass fiber is disposed in the unsealed opening portion to promote air discharge, and a glass yarn 10 is disposed on the inside thereof, and the air in the releasable film 5 is drawn out in advance. Keep it. Next, the base plate 6 and the bagging film 8 are sealed with a sealant 11 leaving the entire periphery.

  When the cross section of the obtained flat plate composite material was polished and observed with an optical microscope having a magnification of 50 times, no voids affecting the strength of the composite material were observed between the layers of the prepreg.

(Example 2)
A unidirectional prepreg with a FAW of 200 g / m ² and an RC of 35% was prepared in the same manner as in Example 1 except that the epoxy resin composition was changed to the composition B shown in Table 1. The concavo-convex surface of the embossed film was attached to the surface side of the prepreg so as to face the prepreg side, and held in a 50 ° C. atmosphere for 12 hours.
The obtained prepreg showed the same form as Example 1 and had a good tack.

Next, 8 sheets of the obtained prepreg were laminated in the same manner as in Example 1, bagged as shown in FIG. 3, and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate-like composite material was polished and observed with an optical microscope having a magnification of 50 times, no voids affecting the strength of the composite material were observed between the layers of the prepreg.

(Example 3)
A unidirectional prepreg with a FAW of 200 g / m ² and an RC of 35% was prepared in the same manner as in Example 1 except that the epoxy resin composition was changed to the composition C shown in Table 1. The concavo-convex surface of the embossed film was attached to the surface side of the prepreg so as to face the prepreg side, and held in a 130 ° C. atmosphere for 10 hours.
The obtained prepreg showed the same form as Example 1 and had a good tack.

Next, eight prepregs obtained were laminated in the same manner as in Example 1, bagged as shown in FIG. 3, and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate composite material was polished and observed with an optical microscope having a magnification of 50 times, no voids affecting the strength of the composite material were observed between the layers of the prepreg.

Example 4
An epoxy resin composition having the composition A shown in Table 1 was prepared, and uniformly applied onto a release paper so as to have a resin basis weight of 54 g / m ² to prepare a resin film. Carbon fiber manufactured by Mitsubishi Rayon Co., Ltd. TR30S (tensile elastic modulus: 235 GPa) is reinforced by inserting the resin film from both sides of the reinforcing fiber sheet, heating it, and FAW is 200 g / m ² RC made 35% unidirectional prepreg.

The concavo-convex surface of the embossed film was attached to the surface side of the prepreg so as to face the prepreg side, and held in an 80 ° C. atmosphere for 4 hours.
The obtained prepreg showed the same form as Example 1 and had a good tack.

Thereafter, eight sheets were laminated using the prepreg in the direction of fiber arrangement of [−45 ° / 90 ° / + 45 ° / 0 ° / 0 ° / + 45 ° / 90 ° / −45 °], as shown in FIG. Thus, it was bagged and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate composite material was polished and observed with an optical microscope having a magnification of 50 times, no voids affecting the strength of the composite material were observed between the layers of the prepreg.

(Example 5)
An epoxy resin composition having the composition A shown in Table 1 was uniformly applied onto a release paper to prepare a resin film having a resin basis weight of 133 g / m ² . Using the resin film and Mitsubishi Rayon carbon fiber cloth, TR3110, there is substantially no resin on the front surface side, and the resin is impregnated in a biased state on the back surface side, with an FAW of 200 g / m ² and RC. A 40% cross prepreg was obtained.

  An embossed film was attached to the surface of the prepreg and held at 80 ° C. for 5 hours. After that, when the embossed film is peeled off, the resin penetrates into the prepreg at the portion corresponding to the concave portion of the embossed film on the surface of the prepreg, and a fiber portion substantially free of the resin is formed on the surface of the prepreg. It was. In addition, at a portion corresponding to the convex portion of the embossed film, a resin-impregnated portion that is sufficiently impregnated with resin and is substantially resin-impregnated with resin is formed. Was confirmed.

  After stacking eight prepregs, bagging as shown in FIG. 3 and curing under the conditions shown in FIG. 4, the cross section of the composite material was observed, and no voids were observed between the layers.

(Comparative Example 1)
Using an epoxy resin composition of composition A shown in Table 1, it was uniformly coated on a release paper so that the resin basis weight was 54 g / m ² , thereby producing a resin film. This resin film was sandwiched from both front and back sides of carbon fiber TR30S manufactured by Mitsubishi Rayon Co., Ltd., which was aligned in a sheet shape in one direction, and heated from both sides to impregnate the resin. Thereafter, the upper release paper was peeled off to obtain a unidirectional prepreg with an FAW of 200 g / m ² and an RC of 35%.

A polyethylene film having a smooth surface was attached to the side of the prepreg where the release paper was not adhered, and the film was held at 80 ° C. for 5 hours.
In the obtained prepreg, the resin was uniformly impregnated to the inside of the carbon fiber tow, and the resin was evenly present on the prepreg surface. Tuck was very sticky.

In the same manner as in Example 1 using the above prepreg, the polyethylene-made film having a smooth surface was peeled off, and the prepreg was immediately subjected to a fiber arrangement direction of [−45 ° / 90 ° / + 45 ° / 0 ° / 0 ° / + 45 ° / 90 ° / −45 °] were laminated, bagged as shown in FIG. 3, and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate-like composite material was polished and observed with an optical microscope having a magnification of 50 times, a very large number of voids were confirmed between the layers.

(Comparative Example 2)
A unidirectional prepreg with an FAW of 200 g / m ² and an RC of 35% was obtained in the same manner as in Comparative Example 1 except that the epoxy resin composition having the composition B shown in Table 1 was used. A polyethylene film having a smooth surface was attached to the side of the prepreg where the release paper was not attached, and the film was held for 12 hours in a 50 ° C. atmosphere.
The obtained prepreg was uniformly impregnated with the resin up to the inside of the carbon fiber tow, and the resin was evenly present on the prepreg surface. Tuck was very sticky.

In the same manner as in Comparative Example 1, this prepreg was peeled off from the polyethylene film having a smooth surface, and immediately after the prepreg was aligned in the fiber orientation direction [−45 ° / 90 ° / + 45 ° / 0 ° / 0 ° / + 45 ° / 90]. Eight sheets were stacked in the direction of [° / −45 °], bagged as shown in FIG. 3, and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate-like composite material was polished and observed with an optical microscope having a magnification of 50 times, a very large number of voids were confirmed between the layers.

(Comparative Example 3)
A prepreg was prepared in exactly the same manner as in Comparative Example 1 except that the epoxy resin composition having the composition C shown in Table 1 was used. A polyethylene film having a smooth surface was attached to the side of the prepreg where the release paper was not adhered, and the film was held at 130 ° C. for 10 hours.
The obtained prepreg was uniformly impregnated with the resin up to the inside of the carbon fiber tow, and the resin was evenly present on the prepreg surface. Tuck was very sticky.

Thereafter, the polyethylene film having a smooth surface was peeled off in the same manner as in Comparative Example 1, and the prepreg was immediately placed in the fiber orientation direction [−45 ° / 90 ° / + 45 ° / 0 ° / 0 ° / + 45 ° / 90 ° / Eight sheets were stacked in the direction of −45 °], bagged as shown in FIG. 3, and cured under the conditions shown in FIG.
When the cross section of the obtained flat plate-like composite material was polished and observed with an optical microscope having a magnification of 50 times, a very large number of voids were confirmed between the layers.

(Comparative Example 4)
The epoxy resin composition having the composition A shown in Table 1 was uniformly applied onto a release paper to prepare a resin film having a resin basis weight of 133 g / m ² . Using the resin film and a carbon fiber cloth manufactured by Mitsubishi Rayon Co., Ltd., TR3110, a cross prepreg impregnated in a state where the resin was sufficiently spread over the entire carbon fiber cloth was prepared.

A smooth and flat polyethylene film was affixed to the prepreg surface and held at 80 ° C. for 5 hours.
When the cross prepreg thus obtained was peeled off, the entire surface of the prepreg was covered with resin. Tuck was very sticky.

  Using this prepreg, 8 sheets were laminated in the same manner as in Example 4. After bagging as shown in FIG. 3 and curing under the conditions shown in FIG. 4, the cross section was observed, and a large amount of voids were observed between the layers. It was.

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Reinforcing fiber sheet 2a Fiber part 3 Matrix resin 3a Resin layer 3b Resin impregnated part 4 Prepreg stack 5 Release film 6 Base plate 7 Surface breather 8 Bagging film 9 Edge breather 10 Glass yarn 11 Sealant

Claims (4)

A prepreg formed by impregnating a reinforcing fiber sheet with a matrix resin,
A prepreg characterized in that a continuous resin layer is present, and at least one side surface is composed of a resin-impregnated portion where the impregnated resin is substantially present and a fiber portion where the impregnated resin is substantially absent .   The prepreg according to claim 1, wherein the one-side surface has a sea-island shape in which the fiber portion constitutes a sea portion and the resin-impregnated portion constitutes an island portion.   The prepreg according to claim 2, wherein an area of the island portion is 1 to 80% with respect to a total area of the one-side surface.   The prepreg according to claim 2 or 3, wherein a distance between centers of adjacent island portions is 1 to 10 mm.

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