JPH06107808A - Molding material for thermoplastic composite - Google Patents

Abstract

PURPOSE:To obtain the title material which is light in wt. and has improved toughness, surface smoothness, weaving properties, and plating properties by winding and covering a combined fiber comprising a discontinuous untwisted thermoplastic matrix fiber and a reinforcing fiber with the matrix fiber of the same kind. CONSTITUTION:A continuous thermoplastic matrix fiber and a continuous reinforcing fiber are separately stretch broken to give a sliver. Two kinds of sliver thus obtd. are mixed to obtain a degree of combining of 20% or higher, and the resulting mixture is cut to give a discontinuous untwisted fiber with a mean length of 50mm or higher. The discontinuous fiber is wound and covered with a continuous thermoplastic matrix fiber of the same kind in a wt. ratio of the former fiber to the latter of 1-10%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber-reinforced composite material in which a thermoplastic resin is made into fibers and mixed with reinforcing fibers.

[0002]

2. Description of the Related Art A molding material for a thermoplastic composite obtained by mixing continuous reinforcing fibers and a thermoplastic matrix fiber is disclosed in JP-A-60-209034 and JP-A-61-13.
It is disclosed in Japanese Patent No. 0345. However,
When these conventional molding materials are used as a blade, the reinforcing continuous fibers are damaged due to the difference in the elongation of the reinforcing continuous fibers and the thermoplastic matrix fibers and the lack of their converging property, resulting in poor operability. Not only is it significantly inferior, but when the blade is molded, there are problems such as generation of impregnation unevenness and the resulting molded body lacking in toughness.

There is also a problem that a molded product having an excellent surface condition cannot be obtained. To improve operability, a large amount of surface treatment agent (spinning oil, etc.) is added to the above fibers.
Although the operability will be improved to some extent by the addition of the above, there is a problem that the surface treatment agent causes the interface strength between the reinforcing fiber and the matrix of the molded article to be lowered.

On the other hand, there is also a composite material in which discontinuous reinforcing fibers and matrix fibers are used to impart twisting properties to these fibers in a so-called spinning process so that the fibers have a bundling property. When a blade is made using this material, it is possible to secure a considerable degree of operability. However, the physical properties of the obtained molded product cannot be satisfactory because of the twist. Further, even in the surface state, the distribution of the reinforcing fibers becomes non-uniform due to the twist, so that there is a problem that a so-called resin-rich portion exists.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermoplastic composite material which is lightweight and tough, has excellent surface smoothness, and has excellent weaving properties and braiding properties. The thermoplastic composite material in which the reinforcing fiber and the thermoplastic matrix fiber are mixed is considered to be an effective material for solving the difficulty of impregnation due to the high viscosity of the thermoplastic resin of the thermoplastic composite material. ing. However, there is no material capable of satisfying both textile processing such as weaving property and braiding property and the physical properties of the composite obtained by molding.

[0006]

As a result of intensive research to solve the above problems, the present invention has been completed. That is, the present invention is a composite molding material comprising a thermoplastic matrix fiber and a reinforcing fiber, wherein the thermoplastic matrix fiber and the reinforcing fiber are mixed, and the degree of mixing is 20% or more, and Consisting of substantially non-twisted discontinuous fibers, which are 1-10% by weight
Is a thermoplastic composite molding material characterized by being wound and coated with the same kind of continuous thermoplastic matrix fiber of the above, and further, a blade and a woven fabric obtained from these thermoplastic composite molding materials.

Here, the degree of mixed fiber is defined by the following equation. Mixed fineness = {100 (N−X) / (N−1)} · {NcX
/ (N / X)} where N represents the total number of reinforcing continuous fibers, NcX represents the number of the continuous reinforcing fibers when divided into some groups (groups), X Indicates the number of filaments in a particular group within the group.
In the above formula, 100 (N−X) / (N−1) is
This means a mixed fiber state, and the smaller the X, the better the mixed fiber state. NcX / (N / X) is a weight.

[0008]

[Working] The thermoplastic matrix fibers used in the present invention include polyamide fibers such as nylon 6 and nylon 66, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, polyolefin fibers such as polyethylene and polypropylene, and polyether ether ketone. Fibers, polyphenylene sulfide fibers, polyetherimide fibers, polycarbonate fibers and the like can be mentioned. However, the thermoplastic matrix fibers used in this invention are not limited to the above fibers.

Examples of the reinforcing fiber used in the present invention include carbon fiber, aramid fiber and glass fiber. However, the reinforcing fibers used in the present invention are not limited to the above fibers.

These thermoplastic matrix fibers and reinforcing fibers are mixed and the degree of mixing is 20% or more. When it is 20% or more, the impregnation into the reinforcing fiber at the time of melting is performed in a short time. When the degree of mixing is less than 20%,
Impregnation takes time and is uneconomical, and the impregnation becomes insufficient, so that the mechanical properties of the molded product deteriorate.

The fibers are non-twisted discontinuous fibers. This is because when a composite is created by molding after making it into a textile product such as a blade or woven fabric, the reinforcing fibers are displaced during molding,
It is a necessary requirement to obtain a product without defects of composite physical properties and surface condition. Further, because of that, it becomes possible to easily form a product having a complicated shape. The average fiber length is not particularly limited, but is preferably 50 mm or more.

As a result of various studies on various measures for imparting textile processability to the fibers, the weight ratio is 1 to 10
It has been found to be effective to wind coat the above fibers with% continuous matrix fibers of the same type as the above thermoplastic matrix fibers. Within this range, the textile processability and the resulting composite physical properties can both be achieved.

The weight ratio mentioned here is defined by the following equation. Weight ratio = {C / (A + B + C)} × 100 (%) A: Amount of thermoplastic matrix discontinuous fibers (g / m) B: Amount of reinforcing discontinuous fibers (g / m) C: Continuous thermoplastic matrix Amount of fiber (wound fiber) (g / m)

In the actual process, the thermoplastic composite material is subjected to heat and pressure, so that the thermoplastic matrix discontinuous fiber (hereinafter abbreviated as a) is mixed with the thermoplastic matrix continuous fiber. The wound component (hereinafter abbreviated as "c") is melted, impregnated into the reinforcing discontinuous fiber, and cooled to form a composite. Therefore, the factors that control the physical properties and appearance of the composite include the molten state of the above two types of thermoplastic matrix fibers.

The main role of the above c is textile processability. That is, it is possible to obtain a blade or a woven fabric without damaging the reinforcing fibers and without disturbing the scattering or orientation state, and cutting into a predetermined shape as a material to be used for molding and preliminarily shaping (for example, a mold or the like). Is meant to be done satisfactorily. Once pre-shaped, it is important to melt as smoothly as possible and leave no trace of wound coating in the subsequent so-called molding process.

If there are traces of the wound coating remaining, they are the main causes of two defects. One is the presence of a resin rich part. Needless to say, the presence of this not only impairs the surface appearance of the resulting molded article, but also reduces the mechanical properties of the molded article. The other one is that the restraining force due to c worked during molding, resulting in insufficient dispersion between the reinforcing fibers, resulting in a lack of physical properties between fiber bundles. For example, when bending properties are measured, cracks occur between fiber bundles, and the obtained physical property values are also insufficient.

Therefore, in order to prevent these defects from occurring, the weight ratio of c must be 10% or less. On the other hand, in order to satisfy the above-mentioned textile processability, c of 1% or more is required. Furthermore, the melt viscosity of c should be smaller than that of a, and the apparent melting point of c should be a.
It is also effective to make the monofilament denier of c smaller than that of a and the like.

Further, in order to satisfy the textile workability with a small amount of c, it is also effective to coat by winding in two directions of S direction and Z direction using c of denier as thin as possible.

As the surface treatment agent for the thermoplastic matrix fiber, so-called spinning oil is generally attached to maintain the passability of the fiber manufacturing process and the post-process. This type of treating agent inhibits the adhesive force between the reinforcing fiber of the composite and the matrix interface, and therefore it is preferably not used as much as possible.

As a means for mixing the reinforcing discontinuous fiber and the thermoplastic matrix discontinuous fiber, each continuous fiber is separately stretched to obtain a sliver, and then the sliver is mixed and stretched. , A method of obtaining a mixed sliver, or after obtaining a sliver by chopping off the reinforcing continuous fiber, and a sliver of matrix discontinuous fibers obtained by a card process or the like and a kneading step, or mixing in a roving step, mixing sliver Any method such as a method of obtaining a mixed roving may be used, but the degree of mixing is preferably 20% or more. Then, the sliver or the like is wound and coated with a thermoplastic continuous matrix fiber by using a hollow spindle or the like. However, the method is not limited to this.

In the present invention, a reinforcing discontinuous fiber,
The mixing ratio with a and c is not particularly limited, but the weight fraction (wf) of the reinforcing discontinuous fiber is 30 to 80%.
Is preferred.

The thermoplastic composite molding material of the present invention includes a filament or a blade composed of the filament,
Includes woven, knit, or multi-axis laminated fabrics. Suitable examples include blades and fabrics.

A round punching blade is manufactured by a round punching machine, and a so-called bag material such as a silicon tube is inserted thereinto,
Frames or bats for tennis rackets and badminton rackets can be made by the internal pressure molding method. Further, by using a circular loom or the like and weaving it into the shape of the finding, it is possible to make a molded article for the same purpose as described above. Further, it is also possible to obtain a woven fabric by using an ordinary biaxial loom or the like and lay up the woven fabric to make a helmet or the like.

It is also possible to form a helmet by forming the woven fabric using a press molding machine or the like to obtain a flat plate and then deep drawing. As described above, the molding material of the present invention has an advantage that it can be applied to a considerable range of molding processing methods. The present invention will be described below with reference to examples, but the present invention is not limited thereto.

[0025]

Example 1 Nylon 6 was used as the thermoplastic matrix fiber (a), and carbon fiber was used as the reinforcing fiber (b).
The average fiber length of each was 100 mm. A molding material for composite (mixed fiber) was prepared by coating the untwisted mixed fiber bundle with a nylon filament (c) of 12 denier 40 denier in the S and Z directions.

The production method was as follows. The above-mentioned a and b were respectively wound to obtain a sliver, and then the sliver was mixed with a kneading machine and drafted to obtain a predetermined mixed sliver. The weight of the mixed sliver is 536 gel /
It was 6 yds. A filament of c was wound around the mixed sliver with a hollow spindle under the condition of 120 T / M to obtain a mixed fiber of Nm1.7.

The weight ratio of b in the mixed fiber was 59%, the weight ratio of c was 1.5%, and the degree of fiber mixing of the mixed fiber was 65%. Using the obtained mixed fiber, a blade composed of three layers having an angle of 30 ° and an inner diameter of 20 mm was prepared with a round striking structure of 32 strokes. A silicon tube was covered on the outer periphery of the mandrel during plating, and after braiding, it was removed from the mandrel together with the blade.

The blade was subjected to internal pressure molding to obtain a hollow pipe having a thickness of 0.8 mm. The molding condition at that time is a pressure of 15 kg / cm.
² , the temperature was 255 ° C., and the holding time was 20 minutes. The obtained hollow pipe was excellent in surface properties and had no resin rich portion, and was a good pipe. The characteristics of this pipe are shown in Table 1.
The bending characteristics were measured according to JIS-K-7055.

[0029]

[Table 1]

[0030]

Example 2 A mixed fiber was prepared in the same manner as in Example 1. However, the nylon 6 filament used for c was 210 denier 48 filament. Therefore, the weight ratio of c in the mixed fiber was 7.2%. The yarn count of the mixed fiber was Nm1.8. A hollow pipe was prepared from the mixed fiber in the same manner as in the example. The obtained hollow pipe was a good pipe with almost no resin rich portion. The results of the characteristics are also shown in Table 1.

[0031]

[Example 3] Using the mixed yarn used in Example 1, a fabric having a basis weight, warp and weft of 15 yarns / inch was prepared. This woven fabric was pressed in a mold at 250 ° C. under a pressure of 10 kg / cm ² for 10 minutes, then cooled and taken out from the mold to form a flat plate. The mixed yarn used was good in weaving property, and the surface property of the flat plate after molding was also good. The characteristics of this flat plate are also shown in Table 1.

[0032]

Comparative Example 1 A mixed fiber and a blade were prepared in the same manner as in Example 1. However, as the c, a mixed yarn in which one Ny6 filament having 40 denier 12 filaments was wound and coated only in the S direction was used. Therefore, the weight ratio of c was 0.7%. This mixed fiber has a poor braiding property, the carbon fiber is damaged or cut during braiding, which significantly deteriorates the working environment, and the obtained blade surface state has a lot of fluff and the fiber arrangement is disturbed. It was not possible to make a hollow pipe.

[0033]

[Comparative Example 2] A mixed fiber, a blade and a hollow pipe were prepared in the same manner as in Example 1. However, the degree of mixed fiber is 12
%Met. This braided fiber was found to have damage and cutting of carbon fiber during braiding, but it was possible to use it as a blade for the time being. A hollow pipe was produced using the blade under the same conditions as in Example 1. The obtained pipe had some parts with insufficient impregnation and had poor surface properties. The results of the characteristics are also shown in Table 1.

[0034]

Comparative Example 3 By the same method as in Example 1, a mixed fiber, a blade and a hollow pipe were prepared. However, as the c, two Ny6 filaments of 300 denier 60 filaments were used, one of which was wound in the S direction and the other was wound in the Z direction to form a mixed yarn. The number of windings was 180 T / M. Therefore, the weight ratio of c was 16%. The braiding property of the yarn was good, but the yarn was generally hard and lacked in flexibility. Molding was carried out using this blade, but because the binding force of c was too strong, a large number of resin rich parts were formed on the surface of the hollow pipe, and it was not practical.

[0035]

Comparative Example 4 Example 3 using the mixed yarn used in Comparative Example 1
An attempt was made to create a woven fabric similar to the above, but the weaving could not be performed because the carbon fibers of the warp fell off severely.

[0036]

[Comparative Example 5] Example 3 using the mixed yarn used in Comparative Example 2
Fabrication similar to the above was performed. Although damage and cutting of the carbon fiber were observed, it was possible to create a woven fabric. A flat plate was prepared from the woven fabric under the same conditions as in Example 2, but some parts with poor impregnability were found due to insufficient degree of fineness of mixing.

[0037]

[Comparative Example 6] Example 3 using the mixed yarn used in Comparative Example 3
However, it was impossible to increase the density of the fabric by 11 yarns / inch or more because the rigidity of the yarn was too high. The woven fabric was molded under the same molding conditions as in Example 2,
It was not possible to obtain a flat plate having a large number of resin-rich parts due to the high binding force due to c and the low density.

[0038]

Industrial Applicability According to the present invention, it is possible to provide a molding material for a thermoplastic composite which is lightweight, tough and has excellent surface smoothness and which is useful for molding a thermoplastic composite.

Claims (4)

[Claims] 1. A composite molding material comprising a thermoplastic matrix fiber and a reinforcing fiber, wherein the thermoplastic matrix fiber and the reinforcing fiber are mixed, and the degree of mixing is 20% or more. Consisting of substantially non-twisted discontinuous fibers, the weight ratio of which is 1 to 10
% Of a continuous thermoplastic matrix fiber of the same kind, which is wound and coated to form a molding material for a thermoplastic composite. 2. The molding material for thermoplastic composite according to claim 1, wherein the reinforcing fibers are carbon fibers. 3. A blade made of the molding material for thermoplastic composite according to claim 1 or 2. 4. A woven fabric comprising the molding material for a thermoplastic composite according to claim 1.