JP2948048B2 - Composite material for bending and its bending method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic composite material for bending and a method for bending the same. More specifically, the present invention relates to a novel thermoplastic composite material capable of bending with simple equipment and a novel bending method using the composite material.

[0002]

2. Description of the Related Art Conventionally, a bent product of a composite material is a thermosetting resin obtained by setting a reinforcing material in a mold having a predetermined shape corresponding to the bent product, injecting the resin into the die, and heat-curing the resin. A composite material or a composite material formed by injecting a thermoplastic resin or a thermoplastic resin obtained by mixing a reinforcing material (mainly, short fibers) into a preheated mold is mainly used. Also,
Recently, a method of forming a fiber reinforced composite material plate using a thermoplastic resin and heating and pressurizing the plate together with a mold from the outside to perform bending processing has been adopted.

[0003]

However, in the method of molding by injecting a thermosetting resin or a thermoplastic resin into a mold having a predetermined shape, the reinforcing fiber content (Vf) of the molded product is high.
It is difficult to increase the mechanical properties (physical properties) of the obtained molded article because the length of the reinforcing fibers used is limited. On the other hand, in a method of obtaining a molded product by heating and pressing a thermoplastic composite material using a mold,
Since Vf can be increased and continuous fibers can be used, a molded article having excellent physical properties can be obtained. However, on the other hand, high temperature and high pressure are required for molding, and moldability is high. There is a problem that it is inferior. In addition, these moldings all require a mold, resulting in high molding costs and are not suitable for molding in which the shape is arbitrarily changed.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by means completely different from the conventional bending, and have reached the present invention. .

That is, the present invention provides a composite material for bending comprising a reinforcing fiber and a thermoplastic resin, wherein the composite material comprises (a) glass fiber and / or aramid fiber.
At least two insulating layers of a reinforced thermoplastic resin layer , and (b) weaving of carbon fibers and / or silicon carbide fibers
Reinforced with an object or one-way alignment material,
It forms a conductive terminal without being coated with butter, and the both ends
The parts excluding are integrally formed in the composite material,
And one heater layer with current generation and heat generation between each insulation layer.
A composite material for bending formed integrally by laminating each heater layer in between , and further, using this composite material for bending, heat is generated by applying electricity to the heater layer, and from the inside of the material, The present invention relates to a method for bending a thermoplastic composite material, wherein the bending is performed by heating and softening and applying an external pressure.

One of the important points of the present invention is that a special sheet-like thermoplastic composite material is used, and the carbon fiber and / or silicon carbide fiber woven fabric present inside the composite material is also used.
Or a bending process while heating by a heater layer made of a unidirectionally aligned sheet material . In the conventional bending of a thermoplastic composite material, since heating is performed from the outside using a mold as described above, the temperature rise and fall time required for molding is long, and the energy consumption is large. Furthermore, since the heat conduction of the thermoplastic composite material is poor, the method of heating from the outside requires that the surface temperature of the composite material be increased, and the reinforcing fibers are raised (spring back), and high pressure is required to prevent this. Become. In addition, in the case of continuous fiber reinforcement, delamination tends to occur in the bent portion, and to prevent this, heating and high pressure of the entire composite material are required.

However, according to the present invention, carbon fibers,
For using the internal heating due to energization onset heat of silicon carbide fibers,
Excessive heating of the material can be prevented, and further, local heating can be performed in the zone, so that good bending can be performed at an extremely low pressure. For this reason, in the present invention, a full-scale die is not required, and bending can be performed using a convenient simple die.

In the present invention, the heater layer used for internal heating of the composite material is effective as a reinforcing fiber of the composite material.
And a material that generates heat when energized
Is necessary . Such materials include a heater layer.
As for the composition of the reinforcing fiber material to be formed,
Woven or unidirectionally drawn carbon fiber or silicon carbide fiber
Aligned sheet materials can be mentioned, but above all, continuous carbon fiber
Fabrics (cloths) are most preferred. These reinforcing fiber materials usually form a heater layer in the composite material while being impregnated with a thermoplastic resin. The heater layer has a thickness of 8 mm or less, preferably 6 mm or less, more preferably 4 mm or less, and is arranged such that the thickness of each composite material layer divided by the heater layer is substantially uniform.

In the present invention, it is also important to form a terminal which is a connection portion between the heater layer and the power supply. In the method of impregnating the conductive fiber base material constituting the heater layer in the composite material with a thermoplastic resin and then forming a through hole to form a terminal, it is not preferable because a current cannot be uniformly supplied to the heater.

In the present invention, both ends of the base material used for the heater layer are exposed outside the thermoplastic composite material without being covered with a resin in order to uniformly supply a current to the heater layer. Preferably, they are connected. By doing so, local excessive temperature rise can be prevented, and bending can be performed under mild conditions.

In the present invention, in order to secure work safety and achieve bending of only a target portion,
It is necessary to limit the energization range and prevent the current from flowing out to unnecessary parts. For this reason, regarding the prevention of electric leakage in the thickness direction of the thermoplastic composite material, when the Vf of the composite material is high, the insulation is insufficient with only the thermoplastic resin surrounding the heater base material. Must be provided.

As a fiber material for forming the insulating layer,
Fabrics, mats, non-woven fabrics and the like made of heat-resistant electrically insulating fibers such as glass fibers and aramid fibers are used. When using a mat, a nonwoven fabric, or the like, it is desirable to use a material having a high entanglement strength between fibers in order to prevent the occurrence of insulation defects during resin impregnation, and to use a thermally weak connection such as a binder. The use of materials made with the material is not preferred. In this insulating layer, the resin impregnated into the fiber material can be used without particular limitation as long as it is a thermoplastic resin.
The thickness of this insulating layer is 0.3 mm or less, preferably 0.1 mm or less.
mm or less.

In order to restrict the electric current flowing through the heater layer in the plane direction of the thermoplastic composite material, a cross-woven fabric of the heat-resistant electrically insulating fiber and the conductive fiber used for the heater material is used as a heater substrate. Is valid. In this case, a cross-woven fabric in which insulating fibers are all disposed in the warp (weft) yarns of the cross-woven fabric and insulating fibers and conductive fibers are disposed in the weft (warp) yarns at an appropriate ratio is particularly preferable. Thereby, the direction of the current can be effectively controlled.

In the present invention, when the thickness of the thermoplastic composite material to be bent increases, it is preferable to provide a plurality of heater layers in the thickness direction. In this case, in order to perform strict temperature control is established the insulating layer so as to sandwich the respective heater layer on the upper and lower sides of the individual heater layer,
It is preferable to eliminate the leakage current.

The composite material of the present invention comprises the above heater layer,
In addition to the insulating layer, a normal fiber-reinforced thermoplastic resin layer can be included.

FIG. 1 shows a heater layer 3 at the center in the thickness direction.
2 is a composite material sheet for bending in which insulating layers 2 are disposed above and below, respectively, and a normal fiber-reinforced thermoplastic resin layer 1 is further laminated and integrated above and below, respectively. FIG. This is an example in which four insulating layers 2 are provided.

The type of the thermoplastic resin used in the present invention is as follows.
There is no particular limitation, and any thermoplastic resin can be used. For example, nylons such as nylon 6, nylon 66, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6
-Polyesters such as naphthalate (PEN), polyetherimide (PEI), polycarbonate (PC),
Polyetheretherketone (PEEK), polyphenylene sulfide (PPS) can be used
But, among others, nylon, polyester, polyether
Ether ketone, polyphenylene sulfide, polyether
-Terimide or polycarbonate is preferred.

The method for producing the novel thermoplastic composite material for bending according to the present invention is not particularly limited. For example, the above-mentioned thermoplastic resin, reinforcing fiber, heater base material and insulating base material are formed into a predetermined structure. After lamination, a method of manufacturing by heating and pressing using a normal hot press, or a normal thermoplastic composite material plate, and a heater base material and the insulating base material above and below it are impregnated with the same thermoplastic resin It is possible to adopt a method in which the integrated heater composite materials are separately prepared, and these are laminated using a hot press so as to have a predetermined configuration to form an integrated sheet. In these productions, it is important to arrange the heater layer at the center in the thickness direction of the composite material and to pay attention to the preparation of the matrix so as not to cover the terminals of the heater with resin.

The thus obtained thermoplastic composite material for bending according to the present invention can be easily bent by the following method.

Since the bending method of the present invention can be carried out at a relatively low temperature and a low pressure, it is possible to perform shaping using a simple mold. Wood materials, 1-3 mmt
Aluminum plate, gypsum, silicon, etc. can be used.

Using these materials, two upper and lower simple dies are prepared according to the shape of the desired molded product, and the thermoplastic composite material of the present invention is sandwiched between the dies, and the upper and lower dies are stopped by a spring. Since the bending method of the present invention can be carried out at a temperature near the softening point, the springback is small, and since heating is performed from the inside of the composite material, interlayer deformation is easy and buckling based on delamination is hardly caused. Does not occur. For this reason, the pressure required for suppressing these is extremely small, and it is sufficient to stop the upper and lower molds with a spring.

Next, a power source is connected to a heater (carbon fiber) terminal provided at both ends of the thermoplastic composite material of the present invention so as to protrude therefrom, and the composite material is electrically heated. A normal 100 V AC power supply is sufficient as the power supply to be used. As the composite material softens, the mold is closed by the spring pressure and the material is shaped.

The cooling of the material can be performed in a short time by stopping the current supply to the heater layer. If more rapid cooling is required, the terminal can be removed and the simple type can be put into water.

In the present invention, the temperature at which the pressure is released is important, and it is necessary to continuously apply pressure until the material is cooled below the softening temperature.

[0025]

According to the present invention, it is possible to bend a continuous fiber-reinforced thermoplastic composite material having a high Vf without using a full-scale mold or press. Especially useful for molding products with slightly different shapes,
For example, it is particularly useful for forming a prosthetic limb material requiring such points.

[0026]

EXAMPLES Next, Examples and Comparative Examples of the present invention will be described in detail, but the present invention is not limited to these Examples.

In these examples and comparative examples, "CF cloth" is a carbon fiber plain weave cloth (3K; CO5343B, 6K; CO6644B) manufactured by Toray Industries, Inc.
"Glass Fiber Cloth" is Unitika UM Glass Co., Ltd.
Glass fiber plain weave cloth (H201)
"Film" indicates a polycarbonate film (L-1250Z) manufactured by Teijin Chemicals Ltd.

[0028]

Comparative Example 1 As a bending material, a general molded plate (thickness: 1.5 mm) of a CF / PC composite material using a CF cloth and a PC resin was used. The formed plate was formed by the following method. That is, a CF cloth as a reinforcing material and a PC film as a matrix resin are alternately laminated, set on a press equipped with a heating device, heated to 300 ° C., and applied under a surface pressure of 30 kg / cm ^{2 for} 20 minutes. Pressed PC was melt impregnated. Next, cool down to 80 ° C or less, and after solidification,
It was taken out from the press to obtain a CF / PC composite material.

In bending the CF / PC composite material, external heating was performed using hot air or an oil bath as a heating method. First, the place to be bent was heated and softened to 200 ° C. or higher. In this state, both ends were bent. The obtained product had no surface smoothness, and buckling due to the CF cloth as a reinforcing material was observed on the inside after bending.

[0030]

COMPARATIVE EXAMPLE 2 The composite material of Comparative Example 1 was heated to the softening point in a press machine with a heating device used in Comparative Example 1 using a mold having a predetermined shape, and subjected to press bending. Further, it was cooled and solidified in a pressurized state to obtain a bent product.
The obtained one had good surface properties and good bendability. However, the molding time was as long as 10 minutes or more. Further, in this method, processing was possible when the material thickness was 1 mm or less, but molding was difficult when the material thickness was 2 mm or more, and the molding time was further increased.

[0031]

Comparative Example 3 The composite material of Comparative Example 1 was used, and self-heating was performed by an energization method as a heating method. That is, first, a material was cut into 50 mm × 300 mm, holes were made at both ends in the longitudinal direction, and a metal rod was passed through the material to form an electrode. The voltage of this electrode was gradually increased through a 5 Kw sled-jack. In this operation, the temperature around the electrode was abnormally increased when several volts (3 to 5 volts) were applied, and the other parts were hardly heated, so that bending could not be performed.

[0032]

Example 1 As a reinforcing material, a CF cloth longer than the other was placed in the center, glass fiber cloths were arranged above and below the other, and the other was a laminate of CF cloths. The PC-based laminate was molded under the same molding conditions as in Comparative Example 1 to obtain a composite material having a cross section as shown in FIG. The thickness of each of the composite material layers 1 on the upper and lower sides of the formed plate is 1.4 m.
m, the thickness of the insulating layer 2 was 0.16 mm, and the thickness of the central heater layer was 0.34 mm.

The obtained plate was cut into a size of 50 mm × 300 mm, and a metal plate was applied to the entire protruded CF cloth as an electrode in order to use the central CF cloth protruding in the longitudinal direction as a heater. A voltage of 10 volts was applied to this electrode using a general 100 volt AC power supply via a 5 kW watt slider as in Comparative Example 3. The current at this time was about 7 amps. About 3 minutes after the start of the pressurization, the surface temperature became almost 150 ° C. in the vicinity of the electrode and in the center of the material, and deformation started. At this time, the power supply was cut off, the product was sandwiched between dies from above and below, and pressed and bent by hand, and then cooled and solidified for about 1 minute. The obtained one had good surface properties and had the same shape as the mold.

[0034]

Example 2 Two layers of CF cloth for heaters each having an upper and lower insulating layer of glass fiber cloth are arranged so as to divide the thickness direction into 1/3, and all other layers are C as a reinforcing material.
A CF / PC-based composite material forming plate as shown in FIG. 2 having an overall thickness of about 7 mm using an F cloth was formed. The molding conditions at this time are the same as those in Comparative Example 1. The thickness of the upper and lower composite material layers 1 in this plate is 1.6 mm, the thickness of the insulating layer 2 is 0.16 mm, the thickness of the heater layer 3 is 0.34 mm, and the thickness of the composite material layer 1 at the center is Was 2.4 mm.

This formed plate was cut into the same size as in Example 1 and two C for heaters arranged in 1/3 of the thickness direction.
The protruding portion of the F cloth was sandwiched between metal plates to form an electrode. This electrode was heated by energization in the same manner as in Example 1, and was bent by a mold. However, pressurization was not carried out by hand, but was tightened using a shrimp, and after pressing and forming, the power supply was removed and cooled and solidified in water. The obtained one had good surface properties and had the same shape as the mold.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a bending composite material used in Example 1 of the present invention.

FIG. 2 is a schematic cross-sectional view of a bending composite material used in Example 2 of the present invention.

[Explanation of symbols]

 Reference Signs List 1 composite material layer (CF cloth / PC layer) 2 insulating layer (glass fiber cloth / PC layer) 3 heater layer (CF cloth / PC layer)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FIB29L 9:00 (56) References JP-A-61-268428 (JP, A) JP-A-4-45916 (JP, A) JP-A-54-101873 (JP, A) JP-A-1-126337 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B32B 1/00-35/00 B29C 31/00- 73/34

Claims (5)

(57) [Claims] 1. A bending composite material comprising a reinforcing fiber and a thermoplastic resin, wherein (a) a glass material is contained in the composite material.
Thermoplastics reinforced with fiber and / or aramid fiber
At least two insulating layers made of a conductive resin layer , and (b) a woven or unidirectional carbon fiber and / or silicon carbide fiber
Reinforced with pulling aligned material, both ends forms a conductive terminal without being covered with a resin, and portions excluding the both ends are integrally formed in the composite, at a minimum energization heat generating resistance
One heater layer and one heater layer between each insulation layer
A composite material for bending, wherein the composite material is laminated so as to be arranged . 2. The method according to claim 1, wherein the heater layer comprises one layer or two layers in the composite material.
It is arranged above the layer, and one layer per thickness Ah below 8mm
And one of the insulating layers laminated above and below each heater layer
The composite material for bending according to claim 1, wherein a thickness per contact is 0.3 mm or less . 3. The heater layer and the matrix resin of the insulating layer are at least one thermoplastic resin selected from nylon, polyester, polyetheretherketone, polyphenylenesulfide, polyetherimide, and polycarbonate. processing the composite material bending according to any one of claims 1 to 2. 4. A composite material for bending according to any one of claims 1 to 3, a heater layer, characterized in that the predominantly consisting union fabric fibers and carbon fibers and / or silicon carbide fibers of the insulating material . 5. Using the thermoplastic composite material for bending according to any one of claims 1 to 4 , energizing a heater layer of the composite material to generate heat, and heating and softening the inside of the material while reducing external pressure. A bending method of a thermoplastic composite material, wherein the bending is performed by adding.