JP2007099966A - Prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg from which a skin material suppressed in resin deficiency, generation of pinhole and generation of not impregnated part, can be formed even in an oven formation under the atmospheric pressure using no autoclave. <P>SOLUTION: In the prepreg which has a base material (A) consisting of reinforcing fibers, a resin film (B) consisting of a thermosetting resin pasted on one surface of the base material (A), and a resin film (C) consisting of a thermosetting resin pasted on the other surface of the base material (A), and in which the base material (A) is impregnated with parts of thermoplastic resins of the resin film (B) and the resin film (C); the impregnation ratio of the thermosetting resins into the base material (A) is 10-60%, and the weight X g/m<SP>2</SP>of the resin film (B) and the weight Y g/m<SP>2</SP>of the resin film (C) satisfy the relation of formula (1); 0.3≤X/Y≤0.7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a prepreg that is an intermediate material when a laminated body in which a hollow core material is sandwiched between skin materials made of prepreg.

A so-called honeycomb sandwich panel, in which a fiber reinforced resin skin material is provided on both sides of a hollow core material having a honeycomb structure, is lightweight and has excellent mechanical properties, so it is widely used in aircraft, automobiles, etc. ing.
A honeycomb sandwich panel is usually manufactured by inserting a film adhesive between a core material and a prepreg in which a reinforcing fiber is impregnated with a thermosetting resin, and heating and pressing them using an autoclave. . However, since the equipment of the autoclave is very expensive, it is not only difficult to introduce a new one, but once it is introduced, the size of the molded product is limited by the size of the autoclave, which makes it possible to produce larger molded products. Virtually impossible.

  Thus, a method for manufacturing a honeycomb sandwich panel without using an autoclave has been studied. For example, an oven molding in which a prepreg, a core material, and a prepreg are sequentially stacked on a mold (hereinafter referred to as a tool), the stack is covered with a bag, the space between the bag and the tool is evacuated, and the oven is heated. (Also called vacuum bag molding) has been proposed. Since the oven molding is performed under atmospheric pressure, a solid pressure-resistant container such as an autoclave is not necessary, and can be performed if there is an oven (furnace) that only performs heating. It can also be implemented with simple equipment such as a heat insulation board and a hot air heater.

Patent Document 1 proposes a method for manufacturing a honeycomb sandwich panel by oven molding using a semi-impregnated prepreg. Semi-impregnated prepreg is a prepreg in which a thermosetting resin film is bonded to one side of a base material made of reinforcing fibers, and a part of the thermosetting resin is impregnated into the base material, or both sides of the thermosetting resin film. It is a prepreg in which a base material is bonded and a base material is impregnated with a part of the thermosetting resin.
However, a honeycomb sandwich panel obtained by oven-molding using a semi-impregnated prepreg has a problem that resin withering or pinholes occur on the surface of the skin material in contact with the tool.

In addition, from the demand for cost reduction, a prepreg using a high-weight reinforcing fiber is required. However, when a base material having a basis weight of 400 g / m ² or more is used as the base material of the semi-impregnated prepreg, it is difficult for the thermosetting resin to be impregnated into the reinforcing fiber by oven molding. For this reason, when the skin material is used, an unimpregnated portion in which the reinforcing fiber is not impregnated with the thermosetting resin is generated, and the excellent mechanical properties of the honeycomb sandwich panel are impaired.
JP 2004-058609 A

  It is an object of the present invention to provide a prepreg capable of forming a skin material in which resin withering, generation of pinholes, and generation of unimpregnated portions are suppressed even in oven molding under atmospheric pressure without using an autoclave. .

The prepreg of the present invention comprises a base material (A) made of reinforcing fibers, a resin film (B) made of a thermosetting resin bonded to one surface of the base material (A), and a base material (A). A resin film (C) made of a thermosetting resin, which is bonded to the other surface, and a part of the thermosetting resin of the resin film (B) and the resin film (C) is a base material (A) The prepreg impregnated with the base material (A) has an impregnation ratio of the thermosetting resin of 10 to 60%, and the weight X (g / m ² ) of the resin film (B) and the resin film ( The weight Y (g / m ² ) of C) satisfies the relationship of the following formula (1).
0.3 ≦ X / Y ≦ 0.7 (1)

  According to the prepreg of the present invention, it is possible to form a skin material in which resin withering, generation of pinholes, and generation of unimpregnated portions are suppressed even in oven molding under atmospheric pressure without using an autoclave.

<Prepreg>
FIG. 1 is a schematic cross-sectional view showing an example of the prepreg of the present invention. The prepreg 10 includes a base material (A) 11, a resin film (B) 12 bonded to one surface of the base material (A) 11, and a resin film bonded to the other surface of the base material (A) 11. (C) 13 and a part of the thermosetting resin of the resin film (B) 12 and the resin film (C) 13 is a prepreg impregnated in the base material (A) 11.

(Base material (A))
The base material (A) 11 is a sheet-like reinforcing base material made of reinforcing fibers, and is composed of an impregnated portion 14 impregnated with a thermosetting resin and an unimpregnated portion 15 not impregnated with the thermosetting resin. .
Examples of the reinforcing fiber include glass fiber, aramid fiber, and carbon fiber. As the reinforcing fiber, a carbon fiber excellent in specific strength and specific rigidity is preferable. The reinforcing fiber is preferably a continuous fiber from the viewpoint of strength and rigidity.

  As a form of the base material (A) 11, a unidirectional material in which reinforcing fibers are aligned in one direction; a woven fabric; a knitted fabric; a multi-fabric in which layers of reinforcing fibers are aligned in one direction or in multiple directions are stitched Stitched sheets and the like. As a form of the base material (A) 11, a woven fabric is preferable in that it has a drape property that can be easily laminated in accordance with the shape of the core material. Examples of the fabric structure include plain weave, twill weave and satin weave.

The basis weight of the substrate (A) 11 is preferably 400 g / m ² or more. In the prepreg of the present invention, even when the base material (A) 11 having a basis weight of 400 g / m ² or more is used, the base material (A) 11 has sufficient thermoplastic resin during the oven molding. Therefore, it is difficult to form an unimpregnated portion in the skin material, and mechanical properties are improved.

  The impregnation rate of the thermosetting resin into the substrate (A) 11 is 10 to 60%, preferably 20 to 50%, and more preferably 30 to 40%. By setting the impregnation rate to 10% or more, the base material (A) 11 is sufficiently impregnated with the thermoplastic resin during the oven molding, so that the non-impregnated portion is hardly formed in the skin material, and the mechanical properties are further improved. Become. By setting the impregnation rate to 60% or less, an unimpregnated portion serving as a degassing passage is sufficiently ensured during the degassing of the oven molding, so the air in the skin material and between the skin material and the tool The generation of voids in the skin material and the generation of pinholes on the surface of the skin material are suppressed, and the mechanical properties and appearance are not impaired.

The impregnation ratio is the area occupied by the impregnated portion 14 by observing the polished cross section of the cured prepreg 10 with a microscope after the prepreg 10 is cured under the condition that the thermosetting resin does not substantially flow during the curing reaction. It is obtained by calculating the ratio.
In order to clearly distinguish the impregnated portion 14 and the non-impregnated portion 15 by observing the cross section of the prepreg 10, the cross section of the prepreg 10 must be polished. For this purpose, it is necessary to heat and cure the prepreg 10. However, when the thermosetting resin is heated, its viscosity once decreases as the temperature rises, and the flow of the thermosetting resin is observed. When the thermosetting resin flows in the curing process, the thermosetting resin enters the unimpregnated portion 15 that has been present in the prepreg 10 from the beginning, and the impregnation ratio of the obtained prepreg 10 is different from that before the curing. End up. Therefore, in the curing of the prepreg 10, the increase in the viscosity of the thermosetting resin due to the curing reaction needs to exceed the decrease in the viscosity of the thermosetting resin due to the temperature increase. For this purpose, the thermosetting resin may be cured by gradually increasing the temperature. For example, a preferable temperature increase rate is 1 ° C./hour or less.

When the polished cross section of the prepreg 10 thus cured is observed with an optical microscope, the unimpregnated portion 15 in the prepreg 10 is observed as a void lacking the matrix resin. When the area of the base material (A) 11 in the photographed microscopic image is a and the area occupied by the unimpregnated portion 15 (void) present in this portion is b, the impregnation rate is expressed by the following formula (2) Is calculated by
Impregnation rate (%) = (ab) / a × 100 (2)

(Resin film)
The resin film (B) 12 and the resin film (C) 13 are films made of a thermosetting resin.
Examples of the thermosetting resin include an epoxy resin, a phenol resin, a bismaleimide resin, a vinyl ester resin, and a benzoxazine resin. As the thermosetting resin, an epoxy resin excellent in mechanical properties is preferable. The thermosetting resin may contain a curing agent, a curing accelerator and the like.

The resin film (B) is a lighter film than the resin film (C), and the weight X (g / m ² ) of the resin film (B) 12 and the weight Y (g / m) of the resin film (C) 13. ^{With 2} ), it is necessary to satisfy the relationship of the following formula (1).
0.3 ≦ X / Y ≦ 0.7 (1)

  By setting X / Y to 0.3 or more, the resin material (B) 12 is less likely to wither resin on the skin material surface formed by performing oven molding in a state where the resin film (B) is in contact with the tool. There is no loss. This is because by securing the amount of the resin film (B) 12 to some extent, the thermosetting resin on the surface of the prepreg 10 may be insufficient even if the thermosetting resin is sucked into the hollow portion (cell) of the core material. This is because the resin withering due to the shortage of thermosetting resin is less likely to occur. By setting X / Y to be 0.7 or less, air between the tool and the resin film (B) 12 of the prepreg 10 in contact with the tool is sufficiently deaerated. Pinholes are less likely to occur and the appearance is not impaired.

(Manufacture of prepreg)
For example, the prepreg 10 is bonded to the one surface of the base material (A) 11 with the resin surface of the resin film (B) 12 formed on the release paper, and to the other surface of the base material (A) 11. The resin surface of the resin film (C) 13 formed on the release paper is bonded together, and the resin film (C) 13 is manufactured by applying pressure while heating from the both sides of the release paper.
An example of the pressurizing means is a fusing press.

<Laminated body>
The laminate is a laminate having a hollow core material and skin materials provided on both surfaces of the core material, at least one skin material being made of the prepreg of the present invention, and the resin film (B) being It is provided to be the outermost layer. In the laminate, resin withering in the skin material, generation of pinholes, and generation of unimpregnated portions are suppressed.
FIG. 2 is a schematic cross-sectional view showing an example of a laminated body. The laminate 20 is a laminate having a hollow core material 21 and skin materials 22 and 23 provided on both surfaces of the core material 21.

  The core material 21 is a molded body having a hollow portion. As the core material 21, a core material having a plurality of columnar open cells is preferable, and a core material having a honeycomb structure (hereinafter referred to as a honeycomb material) is particularly preferable. Examples of the honeycomb material include an aluminum honeycomb made of aluminum, an FRP honeycomb made of fiber reinforced resin (FRP), and an aramid honeycomb in which a non-woven fabric of an aramid fiber is impregnated with a phenol resin.

The skin material 22 is formed by curing the prepreg 10 and is provided so that the resin film (C) 13 of the prepreg 10 is on the core material 21 side and the resin film (B) 12 is the outermost layer.
The skin material 23 is formed by curing a prepreg. The prepreg to be the skin material 23 may be the prepreg 10 or a known prepreg other than the prepreg 10. When the prepreg used as the skin material 23 is the prepreg 10, the resin film (B) 12 of the prepreg 10 may be provided on the core material 21 side, and the resin film (B) 12 is the outermost layer. It may be provided as follows.

  The laminate 20 may have a layer other than the core material 21 and the skin materials 22 and 23. Examples of the other layers include an adhesive layer (not shown) made of a thermosetting resin adhesive provided between the core material 21 and the skin material 22.

<Method for producing laminate>
A method of manufacturing a laminated body includes placing a prepreg, a hollow core material, and a stack of prepregs in order on a tool, covering the stack with a bag, and surrounding the stack with a bag and a tool. In the manufacturing method of a laminate in which the space between the bag and the tool is deaerated, the thermosetting resin of the prepreg is heated and cured, the prepreg of the present invention is used as the prepreg in contact with the tool, and It arrange | positions so that a resin film (B) may contact | connect a tool, It is characterized by the above-mentioned. According to this manufacturing method, it is possible to manufacture a laminate in which the resin withering in the skin material, the generation of pinholes, and the generation of unimpregnated portions are suppressed.

The laminated body 20 is manufactured as follows, for example.
(1) As shown in FIG. 3, a stack in which the prepreg 10, the adhesive sheet 31, the core material 21, the adhesive sheet 31, and the prepreg 16 are sequentially stacked is disposed on the tool 30.
(2) The release film 32 and the non-woven fabric 33 are covered on the stack as necessary, and then the stack is covered with the bag 34.
(3) The bag 34 and the tool 30 are hermetically sealed with a sealant 35 around the stack.
(4) The space between the bag 34 and the tool 30 is deaerated from the vacuum suction port 36 connected to a vacuum pump (not shown).
(5) While performing deaeration, it heats in the oven under air | atmosphere, the thermosetting resin of the prepreg 10 is hardened, and a laminated body is obtained.

When placing the stack on the tool 30, (i) the prepreg 10, the adhesive sheet 31, the core material 21, the adhesive sheet 31, and the prepreg 16 were sequentially stacked in advance at another location. The stack may be disposed on the tool 30. (ii) On the tool 30, the prepreg 10, the adhesive sheet 31, the core material 21, the adhesive sheet 31, and the prepreg 16 are stacked in order. As a result, the stack may be arranged on the tool 30 by forming the stack.
At this time, the prepreg 10 is stacked such that the resin film (C) 13 is on the side in direct contact (or indirectly) with the core material 21 and the resin film (B) is on the side in direct contact with the tool 30.
The prepreg 16 may be the prepreg 10 or a known prepreg other than the prepreg 10. When the prepreg 10 is used as the prepreg 16, the resin film (B) 12 of the prepreg 16 may be stacked so as to be on the core material 21 side, or may be stacked so that the resin film (B) 12 is on the bag 34 side. Also good.
What is necessary is just to determine suitably the heating temperature in an oven, heating time, etc. according to the kind etc. and quantity of the used thermoplastic resin, the physical property requested | required of a laminated body, etc.

Hereinafter, the present invention will be specifically described with reference to examples.
(Preparation of thermosetting resin)
Epicoat 828 (manufactured by Japan Epoxy Resin) 35 parts by mass, Araldite AER4152 (manufactured by Asahi Kasei) 37 parts by mass, Epikote 1002 (manufactured by Japan Epoxy Resin) 28 parts by mass, and EPPN 502H (manufactured by Nippon Kayaku Co., Ltd.) 20 parts by mass A base resin was prepared by dissolving 5 parts by mass of phenotote YP70 (manufactured by Toto Kasei Co., Ltd.) at 160 ° C.

Aside from the base resin, 4 parts by mass of Dicy7 (Japan Epoxy Resin Co., Ltd.) is added to 12 parts by mass of Epicoat 828 (Japan Epoxy Resin Co., Ltd.) and 6 parts by mass of DCMU99 (Hodogaya Chemical Co., Ltd.). A catalyst resin was prepared by uniformly dispersing using the present roll mill.
120 parts by mass of the base resin and 22 parts by mass of the catalyst resin were mixed and uniformly dispersed at 60 ° C. to obtain a thermosetting resin.

[Example 1]
(Manufacture of resin film)
The thermosetting resin was applied to a release paper using a film coater so as to be 150 g / m ² to obtain a resin film (B).
Similarly, a thermosetting resin was applied to release paper using a film coater so as to be 380 g / m ² to obtain a resin film (C).

(Manufacture of prepreg)
As a base material (A), TRK510 manufactured by Mitsubishi Rayon Co., Ltd. (2/2 twill cloth using Pyrofil TR50S12L as a carbon fiber and having a basis weight of 648 g / m ² ) was prepared.
The resin surface of the resin film (B) 12 formed on the release paper is bonded to one surface of the substrate (A) 11, and the other surface of the substrate (A) 11 is formed on the release paper. The resin surface of the resin film (C) 13 was bonded, and the fusing press (Asahi Textile Machine Industry Co., Ltd., JR-600S, treatment length under the conditions of temperature 50 ° C., pressure 0.2 MPa, feed rate 1 m / min. Using a pressure of 1340 mm and a pressure of cylinder pressure), pressure was applied while heating from both sides of the release paper to obtain a prepreg.

(Manufacture of laminates)
An aluminum honeycomb cut to 200 mm × 200 mm (AL1 / 8-52-10P) prepared as a core material was prepared, and a sheet-like epoxy resin adhesive (manufactured by Mitsubishi Rayon Co., Ltd., NB101HC50) was prepared as an adhesive sheet. Prepared.
An adhesive sheet was bonded to both surfaces of the core material, and a prepreg cut to 330 mm × 330 mm was bonded to both surfaces to produce a stack. At this time, the prepreg was bonded so that the resin film (C) was on the side in contact with the core material via the adhesive sheet, and the resin film (B) was on the side in contact with the tool or bag.

As shown in FIG. 3, the stack was placed on a tool, and a release film (Aflon film manufactured by Asahi Glass Co., Ltd.) and a nonwoven fabric were placed on the stack, and these were further covered with a nylon bag.
Next, between the nylon bag and the tool is hermetically sealed with a sealant around the stack, and the nylon bag and the tool are deaerated for 6 hours at room temperature from a vacuum port connected to a vacuum pump. did.

Next, after the stack covered with the nylon bag is put in the oven together with the tool, the temperature is raised from room temperature to 100 ° C. at a heating rate of 1 ° C./min while degassing between the nylon bag and the tool. , Held at 100 ° C. for 1 hour, further heated to 150 ° C. at a heating rate of 1 ° C./min, and then held at 150 ° C. for 2 hours to cure the thermosetting resin of the prepreg and laminate (honeycomb sandwich) Panel).
The following evaluation was performed about the obtained prepreg and laminated body. The results are shown in Table 1.

(Impregnation rate)
The prepreg was put in an oven, heated from 25 ° C. to 150 ° C. at a heating rate of 0.7 ° C./hour, and then held at 150 ° C. for 2 hours. The cross section of the cured prepreg was polished, and the polished cross section was observed with an optical microscope. The area of the base material (A) in the photographed microscopic image was a, the area occupied by the unimpregnated part (void) present in this part was b, and the impregnation rate was calculated from the following formula (2).
Impregnation rate (%) = (ab) / a × 100 (2)

(Pinhole, resin dies)
The surface of the skin material that was in contact with the tool at the time of oven molding was visually observed to confirm the number of pinholes and the presence or absence of resin wilt.
(Presence or absence of non-impregnated skin material)
The laminate was cut with a wet cutter, the cut surface was polished, and the polished cross section was observed with an optical microscope. The presence or absence of an unimpregnated portion (void) of the skin material that was in contact with the tool was confirmed.

[Examples 2 and 3]
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the weight X of the resin film (B) and the weight Y of the resin film (C) were changed to the weights shown in Table 1.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 1.

Example 4
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the temperature during prepreg production was 40 ° C., the pressure was 0.3 MPa, and the feed rate was 2 m / min.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 1.

Example 5
A prepreg and a laminate were produced in the same manner as in Example 1 except that the temperature during prepreg production was 60 ° C., the pressure was 0.15 MPa, and the feed rate was 0.7 m / min.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 1.

Example 6
As a base material (A), TRK101 manufactured by Mitsubishi Rayon Co., Ltd. (a plain woven cloth using pyrofil TR30S3L as carbon fiber and having a basis weight of 400 g / m ² ), a weight X of the resin film (B), and a resin film A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the weight Y of (C) was changed to the weight shown in Table 1.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 1.

[Comparative Examples 1 and 2]
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the weight X of the resin film (B) and the weight Y of the resin film (C) were changed to the weights shown in Table 2.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 2.

[Comparative Example 3]
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the temperature during prepreg production was 100 ° C. and the pressure was 0.4 MPa.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 2.

[Comparative Example 4]
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the temperature during prepreg production was 30 ° C., the pressure was 0.02 MPa, and the feed rate was 4 m / min.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 2.

[Comparative Example 5]
When manufacturing the laminate, the core material and the prepreg are bonded so that the resin film (B) is in contact with the core material through the adhesive sheet and the resin film (C) is in contact with the tool or bag. A laminated body was manufactured in the same manner as in Example 1 except that they were combined.
About the obtained laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 2.

[Comparative Example 6]
A prepreg and a laminate were manufactured in the same manner as in Example 1 except that the weight X of the resin film (B) and the weight Y of the resin film (C) were changed to the weights shown in Table 2.
About the obtained prepreg and laminated body, evaluation similar to Example 1 was performed. The results are shown in Table 2.

In the laminate of Comparative Example 1 where X / Y is less than 0.3, pinholes are generated very little, but the amount of prepreg resin film in contact with the tool is small. The curable resin was sucked in, the resin withered, and the appearance was impaired.
In the laminates of Comparative Example 2 and Comparative Example 6 in which X / Y exceeds 0.7, although resin withering does not occur, the amount of the prepreg resin film in contact with the tool is large. The air in between was not sufficiently deaerated and pinholes occurred frequently.

Since the laminate of Comparative Example 3 using a prepreg having an impregnation rate exceeding 60% had few unimpregnated portions serving as a degassing passage, pinholes were frequently generated because the air in the prepreg could not be sufficiently degassed. Further, since the amount of the prepreg resin film in contact with the tool was small, the thermosetting resin was sucked into the cells of the aluminum honeycomb during the oven forming, and the resin withered.
In the laminate of Comparative Example 4 using a prepreg with an impregnation rate of less than 10%, the base material (A) is not sufficiently impregnated with the thermosetting resin during the oven molding, so that many unimpregnated parts are observed in the skin material. It was.

  In the laminate of Comparative Example 5, since the resin film (C) heavier than the resin film (B) is in contact with the tool, the air between the tool and the prepreg is not sufficiently deaerated during oven molding and remains. There were many pinholes.

  The prepreg of the present invention is useful as a skin material for honeycomb sandwich panels used in aircraft, automobiles and the like.

It is a schematic sectional drawing which shows an example of the prepreg of this invention. It is a schematic sectional drawing which shows an example of a laminated body. It is a schematic sectional drawing for demonstrating the manufacturing method of a laminated body.

Explanation of symbols

10 Prepreg 11 Base material (A)
12 Resin film (B)
13 Resin film (C)

Claims (1)

A base material (A) made of reinforcing fibers;
A resin film (B) made of a thermosetting resin, bonded to one surface of the substrate (A);
Having a resin film (C) made of a thermosetting resin bonded to the other surface of the substrate (A),
A part of the thermosetting resin of the resin film (B) and the resin film (C) is a prepreg impregnated in the base material (A),
The impregnation rate of the thermosetting resin into the substrate (A) is 10 to 60%,
A prepreg in which the weight X (g / m ² ) of the resin film (B) and the weight Y (g / m ² ) of the resin film (C) satisfy the relationship of the following formula (1).
0.3 ≦ X / Y ≦ 0.7 (1)

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