JPH03138136A - Intermediate material for fiber reinforced composite material and fiber reinforced light-weight composite molded material manufactured from the same intermediate material - Google Patents

Abstract

PURPOSE:To manufacture a fiber reinforced composite molded material of light weight and sophisticated shape by providing a specified porous bulky sheet in an intermediate section without using a core material or the like. CONSTITUTION:A towel composed of composite yarns composed of reinforced fiber (a) and thermoplastic fiber (b) and having apparent density 0.4g/cm<3>-1.2g/cm<3> is made into a layer A, while a porous sheet composed of fibers (a) and (b) or fiber (a) and thermoplastic resin (c), or else fibers (a)-(c) and having apparent density 0.02g/cm<3>-0.4g/cm<3> is formed into another layer B. At least the layers A are disposed on outermost layers on both sides respectively, and a layer combining layers B composed of one layer or more, or a layer B composed of one layer or more and a layer A composed of one layer or more is disposed intermediately and laminated integrally. Thus, an intermediate material for fiber reinforced light-weight composite material with enhanced degree of freedom of molding and of light weight and comparatively high strength and also of superior torsional rigidity and also a composite molded material manufactured from said intermediate material can be manufactured without using a core material such as a foamed material or a honeycomb, a foaming agent or hollow glass beads.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to intermediate materials for fiber-reinforced lightweight composite moldings useful for reinforcing members for aircrafts, automobiles, etc., exterior panel materials, reinforcing members for construction, etc. This article relates to a fiber-reinforced lightweight composite molded product obtained from an intermediate material.

(Prior Art) Conventionally, fiber-reinforced composite materials using threads made of reinforcing fibers and thermoplastic fibers have been disclosed in Japanese Patent Laid-Open No. 80-209034, Japanese Patent Laid-Open No. 61-130345, and the like. Heat press forming of fabrics obtained from the composite yarns is also disclosed. However, there is no disclosure regarding a lightweight fiber-reinforced composite molded article using the above-mentioned composite yarn. In addition, in conventional fiber-reinforced lightweight composite molded articles that are intentionally lightweight, the matrix is generally thermosetting in most cases, and has very little thermoplasticity. In the case of this thermosetting type, molding is performed by using a foam or honeycomb as a core material and arranging prepreg around the core material. In the case of thermoplastic materials, some use honeycomb as the core material.

Apart from these methods, there is a method in which a foaming agent is added to the resin and foamed during molding. Similarly, there is a method of reducing weight by inserting hollow glass beads into the resin.

When a fabric obtained from a conventional composite yarn of reinforcing fibers and thermoplastic fibers is heat-pressed, the resulting molded product is
Normally, the inside is in a uniform state as well as the outer layer, and thermoplastic fibers are melted and impregnated between reinforcing fibers to form a matrix, and further weight reduction cannot be expected. The weight of thermoplastic fiber-reinforced composite molded products, which have higher toughness than thermosetting ones, is reduced.
In order to obtain a fiber-reinforced composite molded product with high specific strength and high torsional rigidity, if a foam is used as the core material,
The foam generally has a low melting point, and during the molding process to obtain a molded object, part or all of the foam melts when heated, and the essential role of the foam is lost, making it impossible to mold. On the other hand, when a honeycomb is used as a core material, the honeycomb and the surrounding thermoplastic material are often essentially different, and the adhesion between the honeycomb and the surrounding thermoplastic material after molding is poor. There is a problem with the strength of the obtained fiber-reinforced lightweight composite molded product. Furthermore, the shape of these core materials is generally limited, which limits the shape of the fiber-reinforced lightweight composite molded product, resulting in a low degree of freedom in molding. Further, since the core material is generally hard, it cannot be curved to fit a mold having a complicated shape. Therefore, when molding a complex shape, the core material must be shaped in advance to match the shape to be molded, which is very time consuming. In particular, when molding a fiber-reinforced composite molded product by partially changing the bulk and providing unevenness, the core material must be placed in advance on the white part to be made bulky, which is very time-consuming. It takes. Furthermore, when a foaming agent is used, it is difficult to control the dispersion of the foaming agent and the degree of foaming, resulting in a problem of variations in product quality. Furthermore, when hollow glass beads are used, there is a problem that the hollow glass beads break due to compression during heat press molding, and do not play the role of weight reduction.

(Problems to be Solved by the Invention) Therefore, the present invention does not use a core material such as a foam or honeycomb for weight reduction, a foaming agent, or hollow glass beads, and further,
It is lightweight and has high specific strength, which greatly improves the degree of freedom of molding.
It is an object of the present invention to provide an intermediate material for a fiber-reinforced lightweight composite molded article that has excellent torsional rigidity, and a composite molded article obtained from the intermediate material.

(Means for Solving the Problems) The present invention uses (a) reinforcing fibers, (b) thermoplastic fibers, and/or (c) resins as raw materials, and the above (a) and (c)
(b) The apparent density of the composite yarn is 0.4 g/
cl ~1,2 g/ca fabric for one shoe (
A), and the apparent density of (a) and (b), or (a) and (c), or (a), (b), and (c) is 0.02 g/cm3 to 0.4 g/cm. A porous sheet of cl is another layer (B), and at least layer (A) is arranged on the outermost layer on both sides, and one or more layers (B) or one or more layers CB) and one or more layers. An intermediate material for a fiber-reinforced composite molded article, characterized in that a layer combining the layers (A) is placed in the middle and integrated, and the temperature at which the intermediate material is melted by the above (b) and (c). By heating above
(B) in the layer (A) is melted and impregnated between the above (A) in the layer (A) to form a matrix, and at the same time, the above (B) or (C) in the layer (B), or the above (b) and (c)
melts and wets the surface of (a) in layer (B), so that layer (B) melts and wets the surface of (b) or (a) in layer (B).
The above-mentioned problems are solved by a lightweight fiber-reinforced composite molded article obtained by melt bonding according to c) or (b) and (c), characterized in that the layer (B) arranged in the middle part is bulky. It is something.

That is, without using a core material such as foam or honeycomb, (B
) The layer is bulky and porous to achieve weight reduction, and (B) the thermoplastic fibers or thermoplastic material in the layer melts and adheres to other adjacent layers to ensure adhesion. It is something to do. Moreover, since the lightweight fiber-reinforced composite molded intermediate material of the present invention is a combination of fabric and porous sheet laminated together, it is flexible and easily conforms to complicated molds, and has excellent molding flexibility.

In the present invention, lightweight means that in a fiber-reinforced composite molded article using the same reinforcing fibers and the same thermoplastic material as in the present invention,
In contrast to those in which the reinforcing fibers are impregnated with a thermoplastic substance so that the entire structure is uniform, the present invention is lightweight by including a porous bulky layer. The weight can be reduced by several percent to about 60 percent. However, this varies depending on the purpose of use of the fiber-reinforced lightweight composite molded article and how much porous bulk layer is included, and can be controlled depending on the purpose.

Examples of reinforcing fibers used in the present invention include carbon fibers, glass fibers, aramid fibers, etc., but are not limited to these. , any fiber that does not melt may be selected depending on the purpose. Further, these may be used alone or in combination. There are no particular regulations regarding length or diameter. Further, when using glass fibers, it is preferable to apply a treatment agent in advance according to the thermoplastic fibers and thermoplastic substance used.

Next, examples of thermoplastic fibers include polyolefin, polyvinyl alcohol, polyvinyl chloride, polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ether ketone, etc., but any thermoplastic fiber can be used. You can choose it depending on your purpose. Further, the length and diameter are not particularly specified.

The thermoplastic resin referred to in the present invention has almost the same composition as the thermoplastic fiber, and may be copolymerized or modified to some extent. However, it is desirable that the melting points of the thermoplastic fiber and the thermoplastic resin be approximately the same. This thermoplastic resin is
It is preferable to use it in powder form.

The yarn in which reinforcing fibers and thermoplastic fibers are composited is a yarn in which both fibers are composited as uniformly as possible by a known technique, such as the method using air disclosed in Japanese Patent Application Laid-Open No. 80-209034. The composite ratio of both fibers is arbitrary and may be adjusted depending on the purpose. Preferably, the reinforcing fibers are 30
~E! Although it is Owt%, there is no particular regulation. As described above, since the fiber is a composite thread, the thermoplastic fibers are easily melted and impregnated between the reinforcing fibers, and the impregnation time is also shortened. The (A) layer made of this composite yarn may be a woven fabric, a multi-axial woven fabric, a knitted fabric, a mat-like non-woven fabric, etc., but a multi-axial woven fabric is preferable in terms of flexibility in strength design.

The apparent density here is the basis weight divided by the thickness of the fabric. The basis weight can be measured by the weight of a certain area, and the thickness can be measured with a cloth thickness meter. The apparent density of the layer (A) is 0.4 g/ca to 1.2 g/cd, so that a hard and densely packed layer can be formed.

In addition, the [B] layer of the porous sheet has an apparent density of 0.02
It needs to be porous and bulky with g/cl to 0.4 g/cJ. Since this appearance is in the density range,
Even after molding, the layer (B) has sufficient bulk, and a fiber-reinforced lightweight composite molded product can be obtained. If the apparent density is greater than this range, the bulk will be small and good weight reduction cannot be achieved. Moreover, if it is smaller than this range, the shape cannot be maintained and a desired molded article cannot be obtained. This porous sheet CB) layer is suitably made into a mat shape or knitted with a length of 5 to 70 mm. In particular, double raschel knits are very suitable for achieving the invention.

The porous sheet (31 layers) consists of (1) a combination of reinforcing fibers and thermoplastic fibers, (2) a combination of reinforcing fibers, thermoplastic fibers and the same type of thermoplastic resin, (3) reinforcing fibers and thermoplastic fibers, and Any combination of thermoplastic fiber and thermoplastic resin of the same type may be used.In the case of (1), (A
Examples include those knitted from yarns made of a composite of reinforcing fibers and thermoplastic fibers, similar to the layer 2), and those made by cutting yarns into a mat shape.

In the case of (2), an example is one in which reinforcing fibers are knitted or cut into a mat shape, and then a powdered thermophilic substance is added afterwards. In the case of (3), (A)
Examples include those knitted from threads made of a composite of reinforcing fibers and thermoplastic fibers, similar to the layers, and those made by cutting the threads into a mat shape, which is later added with a powdered thermoplastic substance. The proportion of thermoplastic fibers, thermoplastic resin, or both serving as a matrix in the porous sheet (B) is preferably 5 to 40 wt%, more preferably 10 to 30 wt%.
Wt% is good. This is a thermoplastic material during melt molding) IJ
The proportion of reinforcing fibers is high in order to prevent the wax from impregnating between the reinforcing fibers and causing the matrix to adhere to each other, resulting in loss of bulk.

However, if no matrix is present, the surfaces of the reinforcing fibers will not be wetted or protected by the matrix at all, and therefore the reinforcing fibers will be damaged when external force is applied, making it impossible to maintain strength. In addition, the matrix needs to have the above-mentioned thickness in order to ensure adhesion to other layers adjacent to layer (B). The layer (A) is required at least as the outermost layer on both sides, and needs to be thick enough to maintain surface hardness. Therefore, the number of layers may be stacked and may be determined as necessary. Further, one or more layers (B) are required in the intermediate portion. This can also be done by stacking several layers as necessary, and (A) layer and (
B) The layers may be combined and placed in the middle.

The stacked laminates may be stitched together using the thermoplastic fibers used for layer (A), or may be stitched together using light heat (heat) at a temperature above the melting temperature of the thermoplastic fibers and thermoplastic resin under low pressure. The layers may be integrated by pressing and melt-bonding each layer.

The intermediate material for a fiber-reinforced composite molded body (FIG. 1) obtained as described above is heat-pressed at a temperature higher than the temperature at which the thermoplastic fibers and thermoplastic resin melt.

In this case, the press pressure should not be too high, but it should not be too low either. Preferably, lokg/cm3-4
0 kg/cJ, and the press time should be as short as possible, preferably within 10 minutes.

This is to prevent the thermoplastic polymer (IJ) wax from penetrating into the pores of the layer (B) and causing the layer (B) to lose its bulk. However, the thermoplastic matrix in layer (A) is impregnated between the reinforcing fibers, that is, in a wet-out state, while the thermoplastic matrix in layer (B) is wet-through, which wets the surface of the IJ wax reinforcing fibers. It is necessary to ensure that the condition is as follows.

Furthermore, the layer (B) must be adhered to other adjacent layers by means of a thermoplastic matrix. The object in this state is called a blank and is shown in FIG. In this blank, the layer (B) is compressed by pressing, and the blank has no bulk. By heating the blank again to a temperature at which the thermoplastic matrix (+J Fuchs) melts and flows without applying any pressure, the thermoplastic matrix flows, and due to the springback of the reinforcing fibers in the (B) layer, (B) ) layer expands and becomes bulky again. If the desired shape is formed at the same time, the outer layer will be hard after cooling (A
) layer and a bulky layer (B) in the middle part (FIG. 3). Also,
The blank can be formed into a fiber-reinforced lightweight composite molded article having a complex shape by stamping. That is, since the blank does not contain a hard core material, it expands and becomes flexible due to the melt flow of the matrix by reheating without applying pressure. This makes it possible to perform curved molding along a mold with a complex shape. In this case, in order to give the fiber-reinforced composite molded body the desired bulkiness, the stamping molds have a space between the male and female molds for the desired bulkiness, as shown in Figure 4. must be formed. Furthermore, the mold must be at a temperature below the melting point of the matrix, preferably between the crystallization temperature and the glass transition temperature, in order to solidify the molten matrix.

Further, by similar stamping molding, a fiber-reinforced lightweight composite molded body partially made bulky can be obtained. That is, as shown in FIG. 5, in order to give the fiber-reinforced lightweight composite molded body the desired bulk and the desired bulk, a space corresponding to the desired bulk is formed in the desired portions of the male and female molds. As a result, a fiber-reinforced lightweight composite molded article with partial bulkiness can be obtained. Since stamping molding is possible in this manner, the molding cycle time is short and the cost is low.

(Function) As is clear from the above description, the present invention can reduce weight by having a porous bulky sheet in the middle portion without using a conventional core material. The principle is that thermoplastic fibers, thermoplastic substances, or both in a porous bulky sheet are melted once and pressure is applied to wet the reinforcing fiber surface to form a protective layer. The bonding with the layers is carried out with a molten thermoplastic matrix to obtain a flat plate, i.e. a blank. By heating this again, the middle part expands and becomes flexible using the springback of the reinforcing fibers, and at the same time it is molded in the mold, a fiber-reinforced lightweight composite molded article with a bulky layer in the middle part is obtained. It is. This also shows that stamping molding is possible, and that a fiber-reinforced lightweight composite molded article with a complex shape can be obtained, indicating that the degree of freedom in molding is extremely high.

(Examples) Example-1 The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

E-glass fiber, 1215 denier (9 μm diameter) as reinforcing fiber and nylon 6.2700 as thermoplastic fiber
I made yarn by compounding denier with air. The composite ratio is approximately 31 wt% of glass fiber. The yarn was woven into a plain woven fabric. This plain woven fabric has a thread density of 20 vertical threads/1 nch,
The fabric weight is 700 g/♂ with 20 horizontal lines/1 nch, the thickness is 1.0 m-1, and the apparent density is 0.7 g/cJ. This is called layer (A).

On the other hand, E-glass fiber (303 denier, diameter 9 μm) was used as a reinforcing fiber and nylon E3 was used as a thermoplastic fiber (
130 denier) was composited with air to make yarn. The composite ratio is about 7°vt% glass fiber. The yarn was knitted using a double raschel knitting machine to obtain a knitted fabric having a basis weight of 1000 g/f, a thickness of 10 mm, and an apparent density of 0-1 g/ci.

This is called layer (B).

Cut out the above plain weave to 30 c+a x 30 cm, stack 7 pieces, and place 30 c+a x 30 c+a on top of it.
Two layers of double raschel knitted fabric were layered, and seven layers of plain woven fabric (30 cm x 30 cm) were layered on top of that. The above laminate was stitched using nylon 6 sewing thread (70 denier) to obtain an integrated fiber-reinforced composite molded intermediate material. The above intermediate material was heated at 280°C for 3 minutes using a 50t press.
It was pressed at 10 kg/cJ. The resulting blank had a thickness of 8 mm and an apparent density of 1.48 g/cJ.

The blank was heated to about 290'C for 2 minutes with a far-infrared heater, and the middle part expanded, as shown in Figure 6.
Press molded in a mold at 0°C and reinforced with fibers! A composite molded body was obtained. The fiber-reinforced lightweight composite molded article had a thickness of 20 mm and an apparent density of 0.59 g/cd. This is JIS
Bending tests were performed according to K7055. Table 1 shows the results.
Shown below.

Example-2 The double raschel knitted fabric of layer (B) of Example-1 was knitted only with E-glass fiber (303 denier), and the basis weight was 700.
A knitted fabric having a thickness of 10 g/♂ and an apparent density of 0.07 g/Cd was obtained. Nylon-6 powder was impregnated into the knitted fabric using a vibrator. As a result, the glass fiber content is approximately 80 wt% and the apparent density is 0.088 g/cm3.
It became. The rest was the same as in Example-1, and the thickness was 20 mm.
A fiber-reinforced lightweight composite with an apparent density of 0-58 g/ca was obtained. The bending strength results are shown in Table 1.

Example-3 E-glass fiber and nylon-6 of layer (B) of Example-1
Double raschel knitted fabric made of composite yarn of nylon-6
powder was added using a vibrator.

Glass fiber content is approximately 80wt%, apparent density is 0.1
It was 2g/cJ. The rest was carried out in the same manner as in Example-1 to obtain a fiber-reinforced lightweight composite molded product with a thickness of 20 m and an apparent density of 0.6 Og/cJ. The bending strength results are shown in Table 1.

Comparative Example-1 E-glass fiber and nylon-6 of (B) layer of Example-1
Instead of a double raschel knitted fabric made of a composite yarn of
0 g/,! , thickness 10mm 1 apparent density 0.07
g/cJ was used. The rest is the same as in Example-1,
A fiber-reinforced lightweight composite molded article with a thickness of 2011 and an apparent density of 0.56 g/cd was obtained.

The results of bending strength are shown in Table-1.

Comparative Example-2 Without using the double raschel knitted fabric of layer (B) of Example-1, 10 sheets of the plain woven fabric of Example-1 were stacked, and the fabric was heated at 280°C for 3 minutes at 10 kg/ell using a 50-t press. I pressed it. The obtained product had a thickness of 5ff1111 and an apparent density of 1.4 g/cJ. It was used as it was for the bending test. The results are shown in Table-1.

Comparative Example-3 E-glass fiber (303
denier) and nylon-E3 (300 denier) composite yarn (glass fiber content 50wt%) with an apparent density of 0
．． A 1 g/cJ double raschel knitted fabric was used as the (A) layer, and 5 layers of the double raschel knitted fabric were stacked and integrated, and then,
The same procedure as in Example-1 was carried out. The obtained fiber-reinforced lightweight composite molded article had a thickness of 201 points and an apparent density of 0.25 g/cJ. The bending strength results are shown in Table 1.

(Effects of the Invention) Since the intermediate material for a fiber-reinforced composite molded article of the present invention is flexible, when the intermediate material is heat-formed, it can be closely attached to a mold with a complicated shape, and the intermediate material Since a porous bulky layer is formed in the fiber-reinforced composite molded article, it is possible to obtain a lightweight fiber-reinforced composite molded article having a complicated shape.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a cross section of a composite molded intermediate material, Figure 2 is a schematic diagram of a cross section of a blank obtained by heat pressing the composite molded intermediate material, and Figure 3 is a composite molded product obtained by heating the blank in Figure 2. FIG. 4, FIG. 5, and FIG. 6 are schematic cross-sectional views showing various shapes of composite molded bodies of the present invention in press molds. 1... (A) layer fabric, 2... (B) layer porous sheet, 3... reinforcing fiber, 4... matrix 5... reinforcing fiber is impregnated with IJ Fuchs fat. (A) layer, 6... Reinforcing fibers are wet with IJ Fuchs fat (B)
) layer porous sheet 7...mold

Claims (2)

[Claims] (1) Apparent density 0.4g/cm^3-1.2g/ made of yarn that is a composite of reinforcing fibers (a) and thermoplastic fibers (b)
The fabric of cm^3 is used as one layer (A), and the above (A) and (
(b) or the above (a) and a thermoplastic resin (c), or the apparent density of 0.02 g consisting of the above (a), (b) and (c)
/cm^3 to 0.4g/cm^3 is another layer (B), and at least layer (A) is arranged as the outermost layer on both sides, and one or more layers (B) or An intermediate material for a fiber-reinforced composite molded article, characterized in that a layer that is a combination of one or more layers (B) and one or more layers (A) is arranged in the middle and laminated and integrated. (2) A fiber-reinforced lightweight composite molded article obtained by thermoforming the intermediate material for a lightweight fiber-reinforced composite molded article according to claim 1.