JP2003305741A - Manufacturing method for laminated structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a laminated structure excellent in the peel strength of a skin material. <P>SOLUTION: A core material is held between prepregs and the whole is integrally molded under atmospheric pressure to manufacture the laminated structure. This laminated structure is suitably used for the body part of a moving means, especially for the head structure of a train. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a laminated structure.

[0002]

2. Description of the Related Art In recent years, the weight of the body of transportation means such as automobiles and trains has been increasingly required. In response to such a demand, as a material of the body portion of the moving means, there is a tendency to shift from an aluminum alloy to a fiber reinforced composite material (hereinafter abbreviated as FRP). In particular, a carbon fiber reinforced composite material (hereinafter abbreviated as CFRP) using a carbon fiber having high strength and high elasticity as a reinforcing fiber is often used. Thus, when FRP is used as the material of the body of the moving means, in order to achieve weight reduction while maintaining rigidity and strength, FRP is used as a skin material and a laminated (sandwich) structure integrated with the core material. It is often used as a body, and Japanese Patent Application Laid-Open No. 11-20685 discloses a method for manufacturing a laminated structure as a leading vehicle of a Shinkansen by an autoclave molding method. Molding by pressurizing in an autoclave reduces voids, which is one of the factors that greatly affect the strength of the molded product, and a molded product with high strength can be obtained. Therefore, when considering the strength of the molded product, it is usually molded by the autoclave molding method.

[0003]

However, when pressure molding is performed in an autoclave, pressure is also applied to the core material, and the core material is molded in a compressed and deformed state, resulting in compressive strain. This compressive strain gives a stress that is constantly trying to recover in the molded product. Generally, the stress that tries to recover this compressive strain is integrated in a way that the skin material can contain it, so there is no problem at all,
In the body part of a vehicle that moves at high speed, the skin material was gradually affected by stress due to vibration fatigue, and the core material and the skin material were separated from each other. Particularly, in trains and the like, when passing through a tunnel, a drawing pressure is applied to the rearmost vehicle. Depending on the shape of the vehicle,
The higher the speed, the greater this pulling pressure. Therefore, at the time of passing through the tunnel, in the laminated structure of the vehicle at the rearmost part, the stress that the compressed core material tries to recover the strain is further applied with a force pulling from the outside,
A very large force is applied to peel off the skin material. Moreover, such stress is applied while receiving vibration. Accumulation of these stresses for many years may lead to fatigue-like fracture and peeling of the skin material. Therefore, an object of the present invention is to provide a method for manufacturing a laminated structure having excellent peel strength of a skin material.

[0004]

The method for manufacturing a laminated structure of the present invention is characterized in that a core material is sandwiched between prepregs and integrally molded under atmospheric pressure. Further, it is preferable that the above-mentioned laminated structure is used for the body portion of the moving means. Further, it is preferable that the laminated structure is used for the body portion of the moving means having at least an instantaneous velocity of 100 km / hour or more. Further, it is preferable that the body portion of the moving means is the leading structure of the train. Further, it is preferable that the core material is a foamed resin. Further, it is preferable that no resin is present on at least one surface of the prepreg. Further, it is preferable that the reinforcing material of the prepreg is a woven fabric. Further, in the method for producing a laminated structure, it is preferable that the molding temperature when the core material is sandwiched between the prepregs and integrally molded is 150 ° C. or less. In addition, the above-mentioned method for producing a laminated structure is such that, before the core material is sandwiched between prepregs and integrally molded, the core material is held at a temperature of 50 ° C. or higher and lower than the molding temperature for 10 minutes or more, and then heated to the molding temperature for molding. Preferably. In addition, the manufacturing method of the laminated structure is 20 ° C. higher than the molding temperature.
The rate of temperature increase from a low temperature to the molding temperature is 1 ° C /
It is preferably not more than minutes.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for producing a laminated structure in which a core material is sandwiched between skin materials formed of prepreg, and a laminated structure having excellent peel strength can be obtained. Hereinafter, the structure of the laminated structure will be described.

The core material is not particularly limited, and a foamed resin or a honeycomb structure can be used. Examples of the foamed resin include polyvinyl chloride and polyetherimide foamed resin. Specifically, Rohacell (manufactured by ROHM), R63 (manufactured by AIREX), R
82 (manufactured by AIREX), C70 (manufactured by AIREX),
C71 (made by AIREX), C51 (made by AIREX)
Etc. Examples of the honeycomb structure include Nomex (manufactured by HEXCEL) and general aluminum honeycomb. High elastic modulus in the thickness direction, even if a core material made of a foamed resin in which a large strain remains when molded in an autoclave, production of a laminated structure of the present invention that does not apply a large compressive strain during molding According to the method, it can be preferably used. Further, even when a core material having a low elastic modulus in the thickness direction is used, it is possible to obtain a good laminated structure in which the skin material is less likely to peel off.

As the skin material, a prepreg containing a thermosetting resin as a matrix resin is used. In general, the term prepreg refers to a material in which a reinforcing material is impregnated with a resin in advance. However, in the present specification, it is interpreted in a broad sense, and even if the appearance is not impregnated with a resin, The one in which the reinforcing material is integrated is called a prepreg.

The matrix resin of the prepreg is not particularly limited, and thermosetting resins such as epoxy resin, phenol resin, bismaleimide resin, cyanate ester resin, BT resin, unsaturated polyester resin and vinyl ester resin are used. Epoxy resin having an excellent balance of physical properties and handleability is preferably used. Further, it is preferably flame-retardant.

The reinforcing material of the prepreg is not particularly limited, and carbon fiber, glass fiber, aramid fiber, PBO fiber, steel fiber, polyethylene fiber and the like can be used. Among them, carbon fiber has high strength and high strength. It is preferably used because of its elasticity. Further, glass fiber is preferably used because it is excellent in cost performance.

The prepreg used for producing the laminated structure of the present invention preferably has no resin on at least one surface. As will be described in detail later, in the method for manufacturing a laminated structure of the present invention, a core material is sandwiched between prepregs and molded under atmospheric pressure, so in a prepreg having resin surfaces on both sides, the core material and the prepregs are Air during lamination does not escape during molding, and air tends to remain as voids between layers even after molding. Therefore, for example, a prepreg having a resin surface only on one surface, or a prepreg having no resin on at least one surface such as sandwiching the resin surface with a reinforcing material is preferable.

Further, as described above, when a prepreg having no resin on at least one side is used, the reinforcing material of the prepreg is preferably a woven fabric. If the reinforcing material is a woven fabric, it is possible to prevent the reinforcing material on the surface of the prepreg from falling apart even if the resin does not exist on at least one surface of the prepreg. The form of the woven fabric is not particularly limited, and it may be a normal woven fabric such as a plain weave, a twill weave, a satin weave, or a basket weave, or a UD fabric in which reinforcing fibers aligned in one direction are tied together so as not to come apart. It may be a non-woven fabric or the like. That is, since there is no resin that functions as a binder on the surface where no resin is present, it may be necessary to devise a means to retain the reinforcing material instead. When the core material is a honeycomb structure, the prepreg preferably has self-adhesiveness.

Hereinafter, the method for manufacturing a laminated structure according to the embodiment of the present invention will be sequentially described, but the present invention is not limited thereto. The prepreg that forms the skin material is manufactured by, for example, pasting carbon fiber on a resin surface obtained by uniformly coating an epoxy resin on release paper. At this time, as described above, the carbon fiber as the reinforcing material is not actively impregnated with the epoxy resin, but the resin is not present on the surface opposite to the resin surface with respect to the carbon fiber, that is, at least It is preferable to manufacture the prepreg so that the resin does not exist on one surface.

The prepreg manufactured as described above is placed in a molding die. The laminated structure (inner layer structure) of the prepreg at this time is not particularly limited, but it is preferable to laminate the prepreg so that the fiber directions of the reinforcing fibers are multi-directional because the directionality of strength becomes small. The core material is placed on the prepreg thus laminated, and the prepreg is further laminated thereon. The laminated structure (outer layer structure) of the prepreg at this time is not particularly limited, as in the above-mentioned inner layer structure, but it is preferable to stack the prepreg so that the fiber directions of the reinforcing fibers are multidirectional.

As described above, after the prepreg and the core material are laminated, the prepreg and the core material are bagged with a nylon film or the like, the interior is evacuated by a vacuum pump or the like, and molding is performed in a state where the applied pressure is atmospheric pressure. (Vacuum bug molding, oven molding). In this way, by the molding method that does not apply positive force from the outside, extra compressive strain is not applied to the core material, so that large stress (peeling force) on the skin material does not occur, resulting in high peeling. A laminated structure having strength can be obtained.

Further, it is preferable that the molding temperature when the core material is sandwiched between the prepregs and integrally molded is 150 ° C. or less. When the molding temperature exceeds 150 ° C., the core material becomes soft during molding, and the compression deformation increases even in molding under atmospheric pressure. Further, it is more preferably 100 ° C or lower, and further preferably 80 ° C or lower.

Before the core material is sandwiched between prepregs and integrally molded, it is preferable to hold the core material at a temperature of 50 ° C. or higher and lower than the molding temperature for 10 minutes or more, and then raise the temperature to the molding temperature for molding. As described above, in the method for producing a laminated structure of the present invention, it is preferable to use a prepreg having no resin on at least one surface, but in that case, when the resin is cured before moving, the resin is It is not preferable because the part that could not be moved remains as a void. In order to avoid such a state, it is preferable to hold at a temperature lower than the molding temperature for 10 minutes or more.
At that time, if the holding temperature is 50 ° C. or higher, the resin flow is good, which is preferable, and more preferably 70 ° C. or higher. The holding time is preferably 10 minutes or more, but more preferably 20 minutes or more because the resin can sufficiently flow, and particularly preferably 30 minutes or more.

Further, it is preferable that the rate of temperature increase from a temperature 20 ° C. lower than the molding temperature to the molding temperature is 1 ° C./min or less on average. When the temperature approaches the molding temperature, the viscosity of the resin decreases, but on the other hand, the resin begins to react, so that the viscosity of the resin also increases. When the heating rate is high, the viscosity decreasing effect due to the temperature increase becomes larger than the viscosity improving due to the reaction of the resin, and a phenomenon called resin flow occurs. As described above, the resin is hardened before moving, and the portion where the resin could not be moved remains as a void, so some resin flow is necessary, but if the resin flow is too large, Uneven thickness of molded product, resin withering, Vf as designed (volume fraction of reinforcing fiber)
There is a problem such as not being able to obtain. 20 ℃ from molding temperature
When the rate of temperature increase from a low temperature to the molding temperature is 1 ° C or less on average, the viscosity increase due to the reaction and the viscosity decrease due to the temperature increase are well balanced, and the laminated structure (molded product) has a very clean finish. Becomes Therefore, the rate of temperature rise from the temperature 20 ° C lower than the molding temperature to the molding temperature is 1 ° C /
It is preferably not more than minutes, and when it is not more than 0.6 ° C./minute on average, it is possible to obtain a laminated structure having a more beautiful finish.

The above laminated structure is preferably used for a body of a moving means such as an automobile, a train, an airplane, a ship, a roller coaster, and more preferably, a body of a moving means having an instantaneous velocity of 100 km / hour or more. Department,
More preferably, the body portion of the moving means having an instantaneous speed of 150 km / hour or more, particularly preferably an instantaneous speed of 200 km.
/ Body of the transportation means having more than one hour. As described above, since the laminated structure obtained by the manufacturing method of the present invention has a high peel strength, it has a very good effect by being used in the body part of the moving means that moves at high speed with vibration. Can be demonstrated.

It is preferable that the body portion of the moving means is the leading structure of the train. As the train goes through the tunnel,
In addition to vibration, the front structure of the train's rear vehicle is subjected to a force (pulling force) to peel off a very large skin material.
According to the method for manufacturing a laminated structure of the present invention, it is possible to obtain a laminated structure having high resistance to the force of peeling off the skin material even under the extremely severe conditions as described above.

[0020]

EXAMPLES <Manufacturing of Leading Body Model of Railway Vehicle> (Example 1) 40 parts by mass of Epicoat 828 (manufactured by Japan Epoxy Resins Co., Ltd.), 40 parts by mass of Epicoat 1001 (manufactured by Japan Epoxy Resins Co., Ltd.), Epicron N740
(Manufactured by Dainippon Ink and Chemicals, Inc.) 20 parts by mass, DICY7
(Made by Japan Epoxy Resin Co., Ltd.) 5 parts by mass, DCMU9
Epoxy resin obtained by uniformly mixing 5 parts by mass of 9 (manufactured by Hodogaya Chemical Co., Ltd.) was uniformly applied to release paper, and carbon fiber (“Cross TRK510”, manufactured by Mitsubishi Rayon Co., Ltd.) was attached to the resin surface. However, the carbon fiber was not impregnated with the resin positively, and was adhered to the extent that the resin was not present on the surface opposite to the surface on which the resin surface of the carbon fiber was adhered. The content of the resin was 35% by mass with respect to the total mass of the prepreg.

Using the prepreg manufactured as described above, a leading structure model of a railway vehicle shown in FIGS. 1 (a) and 1 (b) was manufactured. First, a prepreg for forming a skin material is laminated on a resin mold, and a core material (“ROHACEL 51IG”, manufactured by Rohm Co., density; 52 kg / m)
³ , 50 mm thick plate) was placed and further prepreg was laminated. Here, the laminated structure of the prepreg that forms the skin material is [-45 ° / 0 ° / 45 ° / 90 ° /
90 ° / 45 ° / 0 ° / −45 °].
This was covered with a nylon film (bagging), and the inside was evacuated. Then, it was placed in an oven and molded under atmospheric pressure. The temperature in the oven at this time is
As shown in FIG. 2, after the temperature was raised from room temperature to 80 ° C. in 30 minutes and kept at 80 ° C. for 30 minutes, the temperature was raised to 130 ° C. which is the molding temperature in 60 minutes, and the molding was performed in 130 ° C. for 90 minutes. finished. The rate of temperature increase from the temperature 20 ° C lower than the molding temperature to the molding temperature was 0.83 ° C / min.
The appearance of the obtained laminated structure (molded product) was very clean without pinholes.

(Example 2) Flame-retardant epoxy matrix resin # 610 was used as the matrix resin for the prepreg.
A laminated structure (molded product) was obtained in the same manner as in Example 1 except that (manufactured by Mitsubishi Rayon Co., Ltd.) was used. The appearance of the obtained molded product was very clean without pinholes.

(Comparative Example) Molding was carried out in an autoclave (pressure 3).
A laminated structure (molded product) was obtained in the same manner as in Example 1 except that the operation was performed at a pressure of 000 kPa). The appearance of the obtained laminated structure (molded product) was very clean without pinholes.

<Peeling Strength Evaluation Method (1)> The following evaluation tests were performed on the laminated structures (molded articles) obtained in Examples 1 and 2 and Comparative Example. Amplitude of molded product 1
cm, 1 Hz, and after being vibrated up and down 100000 times, the appearance of the peeling of the skin material inside the molded product was examined by a handy type ultrasonic flaw detector (“QUANTUM QBT-2
+ ", Manufactured by NDTSYSTEM).

Since the laminated structure (molded product) obtained in Examples 1 and 2 had no peeling points, it can be said that the laminated structure (molded product) had excellent peel strength. On the other hand, in the laminated structure (molded product) obtained in Comparative Example, peeling was confirmed at three places, and the peel strength was inferior to that of the laminated structure (molded product) obtained in Examples 1 and 2. It has been found.

<Peeling Strength Evaluation Method (2)> The following evaluation test was performed on the laminated structures (molded articles) obtained in Example 1 and Comparative Example. Insert the laminated structure (molded product) into a larger cylindrical body and decompress it so that the part facing the front structure model becomes a suction pressure. With tensile stress applied to the skin material, 100 cm up and down with an amplitude of 1 cm and 1 Hz.
Vibrated 000 times. After vibration, peeling of the skin material inside the molded product is examined by using a handy type ultrasonic flaw detector (“QUANTUM QBT-2 +”, NDTSYST).
(Manufactured by EM).

Laminated structure (molded article) obtained in Example 1
No peeling was observed even under severe conditions, but the laminated structure (molded product) obtained in Comparative Example was 25
Peeling was confirmed at four places, of which four were very large. From the above results, it was found that the laminated structure (molded product) obtained in Example 1 according to the embodiment of the present invention was excellent in peel strength even under severe conditions.

(Example 3) As the matrix resin of the prepreg, low temperature curing matrix resin # 830 (manufactured by Mitsubishi Rayon Co., Ltd.) was used, and the temperature in the oven at the time of molding was from room temperature in 10 minutes as shown in FIG. A laminated structure was obtained in the same manner as in Example 1 except that the temperature was raised to 55 ° C. and held at 55 ° C. for 30 minutes, then raised to the molding temperature of 80 ° C. in 45 minutes and molded at 80 ° C. for 120 minutes. Body (molded product)
Got The rate of temperature increase from the temperature 20 ° C lower than the molding temperature to the molding temperature was 0.83 ° C / min. The appearance of the obtained laminated structure (molded product) was very clean without pinholes.

<Peeling Strength Evaluation Method (3)> The following evaluation test was performed on the laminated structure (molded article) obtained in Example 3 above. Amplitude of laminated structure (molded product) 1
cm, 1 Hz, and after being vibrated up and down 100000 times, the peeling of the skin material inside the laminated structure (molded product) is examined by a handy type ultrasonic flaw detector (“QUANTUM”).
QBT-2 + "manufactured by NDTSYSTEM). After that, 100 cm up and down at 1 cm and 1 Hz.
After vibrating 0000 times, the peeling of the skin material inside the laminated structure (molded product) was inspected by the same method as described above.

Laminated structure (molded article) obtained in Example 3
No peeling was observed after the first 100,000 vibrations, and no peeling was observed even after the subsequent 1,000,000 vibrations. From the above results, it was found that the laminated structure (molded product) obtained in Example 3 according to the embodiment of the present invention has extremely excellent peel strength.

[0031]

According to the method for manufacturing a laminated structure of the present invention, a laminated structure having excellent peel strength can be obtained. Further, the laminated structure obtained by the manufacturing method of the present invention,
Since it has excellent peeling strength, it is suitable for use in the body part of the moving means, particularly in the front structure of the train.

[Brief description of drawings]

FIG. 1A is a side view of a front structure model of a rail vehicle, and FIG. 1B is a front view of a front structure model of the rail vehicle.

2 is a graph showing changes in molding temperature in Example 1. FIG.

FIG. 3 is a graph showing changes in molding temperature in Example 3.

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Claims (10)

[Claims] 1. A method for manufacturing a laminated structure in which a core material is sandwiched between skin materials formed of prepreg, wherein the core material is sandwiched between prepregs and integrally molded under atmospheric pressure. Method. 2. The method for manufacturing a laminated structure according to claim 1, wherein the laminated structure is used for a body portion of a moving unit. 3. The method for manufacturing a laminated structure according to claim 1, wherein the laminated structure is used in a body portion of a moving unit having an instantaneous velocity of 100 km / hour or more. 4. The method for manufacturing a laminated structure according to claim 2, wherein the body portion of the moving means is a leading structure of a train. 5. The method for manufacturing a laminated structure according to claim 1, wherein the core material is a foamed resin. 6. The method for producing a laminated structure according to claim 1, wherein no resin is present on at least one surface of the prepreg. 7. The method for manufacturing a laminated structure according to claim 1, wherein the reinforcing material of the prepreg is a woven fabric. 8. The method for producing a laminated structure according to claim 1, wherein a molding temperature when the core material is sandwiched between prepregs and integrally molded is 150 ° C. or lower. 9. Before the core material is sandwiched between prepregs and integrally molded, the core material is held at a temperature of 50 ° C. or higher and lower than the molding temperature for 10 minutes or more, and then heated to the molding temperature for molding. The method for manufacturing a laminated structure according to claim 1 or 8. 10. The method for producing a laminated structure according to claim 9, wherein the rate of temperature increase from the temperature 20 ° C. lower than the molding temperature to the molding temperature is 1 ° C./min or less.