JPH01111037A - Molding composite fiber cloth - Google Patents

Abstract

PURPOSE: To obtain a composite fiber cloth having excellent strength, elastic modulus and processability and widely utilizable as a reinforcing material for automobile part such as radial tire and various structural parts of machines by compositing an ultra-high tenacity polyethylene fiber with a thermoplastic fiber. CONSTITUTION: The objective composite fiber cloth enabling uniform impregnation of a matrix into reinforcing fiber, generating little voids, having little influence of the melt-molding temperature on the physical properties of the reinforcing fiber, free from the deterioration of performance, etc., end exhibiting good workability by combining and compositing (A) an ultra-high tenacity polyethylene fiber having a tensile strength of >=20 g/de, preferably >=30 g/de and composed of an ultra-high polymer polyethylene having a weight-average molecular weight of >=1×10<5> with (B) a thermoplastic fiber having a melting point lower than the ultra-high tenacity polyethylene fiber by >=10 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fabric as a composite material with excellent strength, elastic modulus, and workability, and is suitable for use in automobile parts such as radial tires, various mechanical structural parts, and the like. can be used in a wide range of fields as a reinforcing material for pressure vessels, vibrators, etc.

[Prior art] Composite reinforcement materials using a thermoplastic resin as a matrix and reinforcing fibers as a dispersion material include, for example, opening glass fiber strands using static electricity, attaching thermoplastic resin powder, and then heating. A method of melting and forming a tape-shaped strand (Japanese Patent Publication No. 47-36467), or a method of forming a flexible strand by coating a flexible thermoplastic resin on a reinforcing fiber strand to which thermoplastic resin powder is attached A method of thermoforming into textiles etc.
56) etc.

[Problems to be solved by the invention] For such composite materials, what kind of reinforcing fibers should be selected, and what methods should be used to make a high melt viscosity thermoplastic resin (hereinafter sometimes referred to as matrix)? ) should be impregnated into the reinforcing fibers uniformly and with fewer voids, or what method should be used to melt and mold the matrix and reinforcing fibers without deteriorating the properties such as the strength and elastic modulus of the reinforced iam. is the key point.

In order to obtain a moldable composite material with good impregnability using the conventional technology as described above, it is necessary to use a micron-sized powder as the matrix, which requires the opening of reinforcing fibers, adhesion and melting of the matrix, and in some cases Not only does it require complicated processes such as coating, which does not have good workability, but depending on the type of reinforcing fiber, the properties of the reinforcing fiber may deteriorate due to the effects of heat during melt molding, which may reduce the performance of the composite material for molding. there were.

The present invention was made in view of this situation, and
The object of the present invention is to provide a composite fiber fabric for molding that has extremely good matrix impregnation properties and excellent strength, elastic modulus, and processability.

[Means for Solving the Problems] The present invention uses a yarn that is a composite of ultra-high strength polyethylene fibers with excellent strength and elastic modulus and thermoplastic fibers whose melting point is 10°C or more lower than that of the ultra-high strength polyethylene fibers. The main point is that it has been formed.

[Function] The present invention uses ultra-high strength polyethylene fibers (hereinafter sometimes referred to as reinforcing fibers) having high strength and high elastic modulus, but the strength is determined by molding from the composite fiber for molding according to the present invention. Considering the strength required for products such as automobile parts and mechanical structural parts manufactured using fabrics made from
It is necessary that the tensile strength is at least 20 g/denier or more, preferably 30 g/denier or more, and more preferably 45 g/denier or more.

Regarding the denier, the total denier of both reinforcing fibers and matrix fibers is 100 to 1000 deniers (10 to 10
When using fibers with 0 filaments, for example, a good opening state can be obtained by electro-spreading, the mixing state of the matrix and reinforcing fibers in the final composite molded product becomes more uniform, and an excellent composite effect is obtained. However, it is not limited to this range.

An example of a method for producing such reinforcing fibers is as follows.

Ultra-high molecular weight polyethylene (e.g. weight average molecular weight 1
×10I' or more, preferably txto' or more ultra-high molecular weight polyethylene), and the resulting gel fiber is solution-spun using a drawing zone (where the inlet temperature is higher than the melting point of the supplied fiber in the solvent used and whose melting point is The obtained fibers are obtained by a new high-magnification drawing method in which the fibers are drawn in multiple stages while passing through a drawing zone (drawing zone) in which the fibers are drawn at a lower temperature, while the exit temperature is higher than the melting point of the supplied fibers and lower than the melting point of the fibers after drawing. It will be done.

The thus obtained reinforcing fibers and matrix fibers are composited to form a fabric, but the matrix fibers must have a melting point that is 10° C. or more lower than the melting point of the reinforcing fibers. That is, when fabric is melt-molded, it is processed at a temperature close to the melting point of the reinforcing fibers, but if the difference in melting point between the reinforcing fibers and the matrix fibers is less than 10°C, it is difficult to control the temperature in the fabric melt-molding process. Furthermore, the physical properties of the reinforcing fibers may change under the influence of heat, and there is a risk that the strength and other performance of the final composite molded product may deteriorate.

If the melting point of the matrix fiber is 10°C or more lower than the melting point of the reinforcing fiber, a temperature higher than the softening point of the matrix fiber (
It is relatively easy to melt and mold the reinforcing fibers at a temperature that is preferably at least a temperature sufficient to melt the matrix fibers, but which is lower than the melting point of the reinforcing fibers. Therefore, the impregnation of the reinforcing fibers with the matrix is uniform and sufficient to reduce voids, and the physical properties of the reinforcing fibers are not affected by the melt forming temperature and the performance etc. are not deteriorated in the final composite molding. can get things.

The matrix fiber is not particularly limited as long as it is made of a fiber-forming thermoplastic polymer that satisfies the above temperature conditions, and examples thereof include polyethylene fiber, polybutene-1 fiber, etc., but reinforcing fibers produced by the above method When using polyethylene fiber (melting point 110-137°C), the matrix fiber is polyethylene fiber (melting point 110-137°C).
), polybutene-11a fiber (melting point 120-130°C) is particularly preferred.

Methods of compositing reinforcing fibers and matrix fibers include a method of compositing them in a non-mixed fiber state and a method of compositing them in a mixed fiber state. The non-mixed fiber state means that the reinforcing fibers 1 and the matrix fibers 2 have a side-by-side shape as shown in Figure 1 (cross-sectional view), or a sheath core shape as shown in Figure 2 (cross-sectional view). This refers to the case where The former can be formed by pulling or twisting, and the latter can be formed by a covering method.

On the other hand, in a mixed fiber state, reinforcing fiber 1 and matrix fiber 2 are
As shown in Figure 3 (cross-sectional view), this refers to a state in which the fibers are almost completely mixed with each other. In order to uniformly disperse the fibers, reduce voids, and improve the strength of the final composite molded product, it is more preferable to composite the fibers in a mixed fiber state.

As described above, since the present invention uses fibers as a matrix instead of powder, it does not require complicated operations in either the composite process or the melt molding process, and can be mixed or unmixed. Whichever fiber is used, the workability of the manufacturing process is extremely excellent.

The method for combining matrix fibers and reinforcing fibers in a mixed fiber state is not limited, and examples thereof include the Naslan method, the electrospreading method, and the interlacing method.

These methods will be explained below.

(1) Naslan method This method is a turbulent flow disturbance method in which a plurality of filaments are supplied in a relaxed state to a fluid turbulent region by an air jet, forming loops or entanglements to form a bulky yarn. By this method, single fiber filaments are separated from each other and disturbed in a turbulent region, and by continuously taking them out of the turbulent disturbance region without applying tension, a bulky yarn with irregularly mixed loops and entanglements is instantly created. can be obtained.

By applying this technology to the composite of reinforcing fibers and matrix fibers, the composite fibers can be composited with extremely high production efficiency. As mentioned above, the characteristic of the composite yarn produced by the turbulent flow disturbance method is that many loops and entanglements are formed. It is also extremely easy to melt-form a fabric using strips. That is, for matrix fibers such as polyethylene and polybutene-1,
By reducing the feed rate of the reinforcing fibers and increasing the tension, loops and entanglements of the matrix fibers are formed with respect to the reinforcing fibers in the disturbed area. In particular, reinforcing fibers have a high modulus, so swirling in the disturbed region can be reduced by simply increasing the tension a little. Another important point is the feed rate ratio, which is determined by the mixing ratio of the reinforcing fibers to the matrix fibers, preferably 0.05 to 0.5 times, preferably 0.1 to 0.
Preferably, it is three times faster. If it is 0.05 times or less, the reinforcement efficiency in the final composite molded product will be poor;
If it is 5 or more, the void ratio of the final composite molded product will be high, and the reinforcing fibers may form loops or entanglements in the disturbed area, which is undesirable. According to the turbulence disturbance method, the total denier and number of filaments of the fibers are determined by the feed speed ratio, nozzle shape,
Determined by mechanical conditions such as fluid pressure, but 100
Preferably, fibers of ~1000 denier and 10 to 100 filaments are used.

(2) 1. A method for manufacturing composite yarn by mixing 1 Kusarai filament and stable. The filament is opened using an electric opening device, and the stable is overlapped just before the front roller and heated. However, there is a method of evenly mixing and arranging the fibers by winding the fibers. According to this method, it is possible to obtain a yarn in which filaments and stables of different fibers are continuously and uniformly mixed.

By applying this method to the present invention, extremely uniform composite yarns can be produced. In this case, reinforcing fibers are suitable because they can be opened in a good state by applying voltage.
Ru.

When using this method, denier and filament of 100 to 1000 denier and 10 to 100 filament are suitable.By twisting after opening the collar and mixing, it is possible to improve the operability in the fabric manufacturing process, and furthermore, it is possible to improve the operability in the fabric manufacturing process. The backing becomes denser and can also contribute to reducing voids during melt molding.

(3) Interlacing method The interlacing method creates two or more vortex turbulent zones almost parallel to the yarn axis, guides the filament into these zones, and applies tension to the extent that no loops or crimps occur.
The principle of the method, which is a technique for producing tight, non-bulky strands, is to impinge on the filament so that the fluid is perpendicular to the filament axis, while at the same time creating a turbulent vortex flow parallel to the filament. This turbulent eddy flow splits the filament bundle to an extent that corresponds to the tension of the yarn and the speed or pressure of the fluid, and at the same time false twists the individual filaments completely at random, causing them to fold and interlace.

The degree of interlacing achieved is influenced by tension, fluid pressure, overfeed rate, filament denier, filament, yarn modulus, etc. The effects of using the interlace method include high productivity, uniform mixing between fibers, and the ability to easily manufacture composite yarn fabrics, while minimizing voids during melt molding and sewing. There are many things that can be mentioned. Particularly important points in this method are overfeed rate, tension,
Liquid pressure, denier, and filament number 0 reinforcing fibers generally have a higher modulus than matrix LA fibers, so it is necessary to set the overfeed rate slightly higher, and it is preferably set to 105 to 110% by weight. This is very important. The matrix fibers may be set based on the overfeed rate of the reinforcing fibers depending on the content. Similarly, the reinforcing t under tension and fluid pressure
The key point is to process the A-fiber under slightly higher conditions than conventional manufacturing conditions for clothing yarn. especially,
Fluid pressure should be 10-50 ps for uniform mixing
ig, preferably 30-50 psig.

is suitable. In addition to the above-mentioned conditions, the denier and number of filaments of the open fibers to be composited are also important for uniform fiber separation and mixing. Since mixing within the turbulent vortex region is closely related to the linear density, it is preferable that the linear densities be the same in order to achieve uniform mixing.

In the present invention, denier of 100 to 10
It is preferable that fibers of ~100 filaments are interlaced, and the denier of the single fibers is 1 to 1.
If it is 0 denier, preferably 1 to 3 denier, it shows good workability and productivity, and even in the weaving/knitting process and the melt molding process, sufficient processability can be obtained, resulting in an excellent composite molded product.

The composite fiber yarn for molding obtained in this way (hereinafter sometimes referred to as car yarn) can be formed into a fabric alone and used for melt molding, or the yarn can be used as a part of the fabric. use,
A fabric can also be formed and melt-molded by using matrix fibers for the remainder.

No matter which method is used above, if the mixing ratio of reinforcing fibers and matrix fibers in the obtained fabric is less than 5% (meaning % by weight, the same applies hereinafter), the final composite molded product If the reinforcing efficiency is poor, on the other hand, if it exceeds 80%, the content of the matrix will be low, the degree of impregnation will be poor, and the void ratio of the final composite molded product will be large, which is not preferable.

Therefore, the content of reinforcing fibers in the fabric made of yarn is 5 to 8.
0%, preferably 10-70%, more preferably 20-70%
It is 60%.

When forming a fabric from yarn, comparing the above-mentioned method of using yarn alone and method of using a mixture of yarn and matrix fibers, it is possible to achieve a uniform mixture of reinforcing fibers and matrix fibers. In terms of properties, the former method is superior and more preferable; in other words, when using the former method, uniformity can be obtained at the level of the single fibers that make up the yarn, but when using the latter method, uniformity can be obtained at the level of the single fibers that make up the yarn, but when using the latter method, uniformity can be obtained at the level of the single fibers that make up the yarn. This is because the uniformity among the matrix fibers remains constant.

Therefore, the impregnation of the matrix fibers into the reinforcing fibers and the strength properties of the final composite molded product are also excellent in the former case.

By the way, the fabric of the present invention includes woven fabrics, silk fabrics, and nonwoven fabrics. Examples of weaving structures include not only the ternary structures such as plain weave, twill weave, and satin weave, but also their conductive structures, shading weave, ridge weave, torn twill weave, and herring twill weave. In addition, various weave structures are exemplified depending on the intended use, such as batten plain weave, leno weave, and mock-shape weave, which are usually used as weave structures for reinforcing cloth such as glass cloth, but the present invention is not limited to these. Furthermore, when the melt-molded product is used as a unidirectional reinforcing material or a diagonal laminate, a thread is used in either the warp or the weft (preferably the warp), and this thread is used in the other one. The same type of matrix fibers may be woven, a predetermined number of fibers may be laminated at a predetermined angle, and then melt molded. Furthermore, when constructing a knitted fabric using threads, any method such as warp knitting, circular knitting, or horizontal knitting may be used, and any knitting structure may be adopted. In particular, the use of a formed sheet melt-formed after knitting may be used. In order to increase the ratio, it is preferable that the yarns are knitted in the form of a lay-in or a tuck-in without forming a stitch, and a lay-in is more preferable. As a knitting structure that provides lay-in using the warp knitting method, the warp yarns of composite yarns can be inserted in a 0-O/1-1 reed motion, and this knitted fabric is highly reinforced in the warp direction. Become.

In addition, in order to highly strengthen both the warp and weft directions, a weft insertion stitch may be added in addition to the warp insertion stitch, and these knitted fabrics can be easily knitted with a warp knitting machine. . Circular knits and yokozuna are excellent at strengthening in only one direction, so by laminating knitted fabrics in a desired direction, they can be used as unidirectional reinforcements or diagonal laminates.

The sheet for a composite molded article produced from the yarn according to the present invention by knitting, weaving, etc. is cut into a predetermined size and stacked in a number equal to the weight of the composite molded article for use in the secondary processing process. Use as a sample.

The sample, which has been preheated to a temperature above the softening point of the matrix fibers (preferably sufficient to melt the matrix fibers), is then placed in a mold.

Finally, the mold is pressed to form the desired shape.

Press pressure is generally 50 to 150 K relative to the projected area.
g/+em' is required, and the faster the pressurizing speed, the better 1
~2 seconds is suitable. The temperature of the mold is preferably below the melting point of the matrix fibers, and the cooling time is determined by the thickness of the thickest part of the molded product. In addition, the sheet for the composite molded product may be prepared by melting and impregnating matrix fibers in advance using a hot press roll, etc., and then using the blank as a blank, keeping the preheating temperature at or below the melting point of the matrix fibers, and subjecting it to solid phase stamping by plastic deformation. can.

Examples will be described below, but the present invention is not limited to the following examples, and it is within the technical scope of the present invention to make appropriate design changes in accordance with the spirit described above and below.

[Example] In the following examples, the strength and elongation characteristics of fibers were measured by the following method.

Using Tensilon manufactured by Toyo Baldwin Co., Ltd., the S-S curve of a single fiber was measured at a sample length (gauge length) of 30 mm and an elongation rate of 100%/min, and the tensile strength (g/d) and initial elastic modulus (g/d) were measured. ) was calculated.

The initial elastic modulus was calculated from the maximum slope near the origin of the SS curve. Each characteristic value was the average value of the values measured using 20 single fibers (5) 1.

400 denier with a tensile strength of 32g/denier,
Ultra-high strength polyethylene fiber with 200 filaments (molecular weight = 2 million, melting point: 147°C) and 400 denier,
Polyethylene fiber with 150 filaments (melting point: 12
Composite yarns were manufactured using an interlacing machine with two pairs of opposing fluid conduits opened using a material with a temperature of 0°C.

A composite yarn of 850 denier in which both the fibers were uniformly mixed was obtained by binding at a fluid pressure of 50 psig and compounding at a speed of about 500 m/min in a wrapping region.Then, the composite yarn was used as a warp. A plain weave fabric with a warp density of 50 threads/inch and a weft density of 50 threads/inch was woven using the same polyethylene fibers as those used for the composite yarn as weft threads. A sheet cut out with dimensions of 20 cm x 20 cm from the plain weave fabric was used as a sample, and vacuum-dried at 80°C for 16 hours under conditions of 0.1 lllmHg or less, so that the composite yarns of each layer were in the same direction. It was layered like this. This laminated sheet was filled into a mold preheated to 120°C and
Preheat melt for 5 minutes then 50-70 Kgf/cm
Heat compression molding was carried out at a pressure of '. It was rapidly cooled to 60° C. under pressure before being removed from the mold.

The polyethylene fibers used for the composite yarn and the weft are melt-molded in the above steps and are melted and impregnated into the remaining ultra-high strength polyethylene fibers as reinforcing materials. A directionally reinforced laminate was obtained. This laminate was subjected to a tensile test in accordance with JIS K7054 with the axial direction of the ultra-high strength polyethylene fibers as the longitudinal direction of the test piece. As a result, the volume content of ultra-high strength polyethylene fibers was approximately 35% in the test piece. Yes, 122
Tensile strengths of 0 to 1320 MPa were obtained. Further, the void ratio of the laminate was 2% or less, and it had an extremely excellent appearance.

A composite yarn made of the same materials as in Example 1 was manufactured. The denier of the composite yarn was 800 denier. Next, this composite yarn was used for the warp and weft to produce a plain woven fabric with a warp density of 50 pieces/inch and a weft density of 50 threads/inch.

From this fabric, 20 cm x 20 c as in Example 1
A sample was prepared by stacking three sheets cut out to a size of m. This sample was subjected to vacuum drying, preheating melting, and compression molding under the same conditions as in Example 1 to obtain a reinforced laminate having a weight of 1.5 mm. The volume content of ultra-high strength polyethylene fibers in this reinforced laminate was approximately 50%, and the void ratio was 2% or less.

In addition, when this laminate was subjected to a tensile test based on JIS K7054, it was 1700 to 1850 MPa.
It was isotropic and had a tensile strength of .

[Effects of the Invention] As described above, the present invention is a fabric made of a composite of ultra-high strength polyethylene fibers having excellent strength and elasticity and thermoplastic fibers having a melting point 10°C or more lower than the ultra-high strength polyethylene fibers. Extremely good impregnability, few voids, strength,
A composite molding fabric with excellent elasticity and processability can be provided with good workability.

[Brief explanation of the drawing]

FIGS. 1 and 2 are sectional views illustrating an example of a non-mixed fiber state in the present invention, and FIG. 3 is a sectional view similarly illustrating an example of a mixed fiber state. 1... Ultra-high strength polyethylene fiber 2... Thermoplastic organic fiber Figure 1

Claims (2)

[Claims] (1) Molding characterized by being formed from a composite yarn of ultra-high strength polyethylene fibers with excellent strength and elastic modulus and thermoplastic fibers whose melting point is 10°C or more lower than that of the ultra-high strength polyethylene fibers. composite fiber fabric. (2) The conjugate fiber fabric for molding according to claim 1, wherein ultra-high strength polyethylene fibers and thermoplastic fibers are composited in a mixed fiber state.