JPH02139438A - Continuous filament bundle reinforced by mixing stable fibers - Google Patents

Abstract

PURPOSE:To obtain the title continuous filament bundle having the mixed filament uniformity, high bulkiness and high industrial value by admixing thermoplastic short-cut fibers into a continuous filament bundle for reinforcement. CONSTITUTION:A continuous filament bundle, preferably more than 1,500 filament count, for reinforcement such as carbon or glass filaments are combined with short-cut fibers of a thermoplastic resin which is prepared by melt-spinning a thermoplastic resin such as polyolefin into filaments and cutting them, preferably in 3 to 150mm length in an amount of 30vol.%, calculated on the basis of the reinforcing filaments, additionally, when needed, inorganic or organic filler, whiskers, pigments and other additives to give the subject continuous filament bundle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a short fiber mixed reinforced long fiber bundle in which thermoplastic resin short fibers are mixed in a reinforcing fiber bundle.

More specifically, the present invention relates to a short fiber mixed reinforced long fiber bundle having a mixed fiber state suitable as a fiber reinforced material and having appropriate bulkiness.

[Conventional technology]

In recent years, fiber-reinforced materials made by bonding reinforcing fibers with various matrix resins have been used in a wide range of applications due to their excellent properties, such as high strength, high rigidity, low specific gravity, and high fatigue resistance. It has high expectations and is attracting attention as a leading industrial material.

Generally, when obtaining a fiber-reinforced material in which these reinforcing fibers are combined with a matrix resin, the resin is easily dispersed uniformly in the fibers, and is flexible and has excellent shapeability.
Thermosetting resins that have excellent fluidity before curing are generally used.

However, in the curing reaction of these thermosetting resins, -
It requires high-temperature pressurization conditions inside the shell for a long time (usually over 1 hour), which poses a problem in productivity.

Furthermore, there are serious drawbacks in that volatile components are likely to be generated and voids remain in the product, which has limited the general use of fiber-reinforced materials.

Therefore, attempts have been made to use thermoplastic resins instead of thermosetting resins (for example, Japanese Patent Laid-Open No. 58-2965
Publication No. 1). However, the thermoplastic resins used for these fiber-reinforced materials have high rigidity at room temperature, and for this reason, it is necessary to simply impregnate the fibers with a resin solution and then use a solvent, or heat-melt a sheet-like film to form the fibers. The prepreg obtained by press-fitting and dispersing the prepreg is rigid at room temperature, and its fibers break when it is forcibly bent, resulting in poor formability, which limits its use.

Therefore, the development of reinforcing fiber bundles and prepregs using thermoplastic resin matrices with excellent shapeability has been actively conducted in recent years.

In addition, as a solution to this problem, it has been disclosed that thermoplastic resin is made into a fiber form and mixed with reinforcing fibers for use (JP-A-60-56545, JP-A-60209033).
Publication No.).

[Problem to be solved by the invention]

Thermoplastic resin fiber (hereinafter referred to as (T) fiber) described in JP-A No. 60-56545. ) and reinforcing fibers is simply a mixture of fiber bundles and is not uniformly mixed. Although this product has fewer single fiber breaks and is easy to handle in subsequent processes, it is difficult to uniformly impregnate the reinforcing fibers with resin during hot melt molding.
There are some drawbacks.

Therefore, in Japanese Patent Application Laid-Open No. 60-209033,
In order to facilitate resin impregnation, we are trying to mix the single fibers with each other. However, mixing long fibers (continuous fibers that are not spun yarns) uniformly in the longitudinal direction at the level of single fibers has a serious drawback that if there is a slight twist in the raw long fibers, only the twisted portion will not be mixed. Also, depending on the blending method, single fiber breaks (so-called fuzz) may occur, and the single fiber breaks may wrap around the roll.
A problem arises in that the signals are transmitted one after another and the entire system eventually breaks down. Therefore, there are restrictions on the use of the above products, -
It has not yet become widespread.

Furthermore, since the above-mentioned products are made of a mixture of long fibers, they lack bulkiness, and there are limitations in making thin products that take advantage of the light weight characteristic of reinforcing fiber materials.

In this way, with regard to reinforced long fiber bundles and TP woven fiber mixtures, a material that is uniformly mixed in both the cross-sectional and longitudinal directions at the single fiber level and has bulky properties has not been found so far. , its development was strongly desired.

SUMMARY OF THE INVENTION In response to such demands, an object of the present invention is to provide a reinforced long fiber bundle for fiber-reinforced materials that is excellent in uniform fiber blending properties and bulky.

[Means to solve the problem]

The above object is achieved by the short fiber mixed reinforced long fiber bundle of the present invention, that is, the short fiber mixed reinforced long fiber bundle characterized in that TP short fibers are mixed in the reinforced long fiber bundle.

The present invention will be explained in detail below.

In the present invention, reinforced long fiber bundles are used.

In general, even if fibers have high strength, they are very weak as single fibers, so they are produced in bundles. The present invention is applied to such bundle-shaped reinforced long fibers.

Regarding the number of single fibers in the reinforced long fiber bundle in the present invention, it may be small or large, but if it is small, simply mix the fiber bundles together! The difference in the effect of the degree of plucking becomes smaller.

Preferably, the number is 500 or more.

As the reinforcing long fibers of the present invention, all long fibers that are generally used in fiber-reinforced materials can be used, but examples include carbon fibers, glass fibers, aramid fibers, silicon carbide fibers, boron fibers, metal fibers, Examples include substantially continuous fibers such as benzothiazole fibers, polybenzoxazole fibers, and alumina fibers.

The thermoplastic resin short fibers (TP short fibers) referred to in the present invention are:
Fibers are produced by melting thermoplastic resin with heat, solvent, etc., turning it into fibers, and then cutting the fibers.

Examples of thermoplastic resins include polyolefins, thermoplastic polyesters, thermoplastic polyamides, acrylic resins, polyoxymethylene, polycarbonate, polyphenylene ether, polystyrenes, polyphenylene sulfide, polyether/ether ketone, polyether ketone, Known thermoplastic resins include polymers such as polyetherimide, polyetherketone, thermoplastic polyamideimide, fluororesins, and copolymers thereof.

These may be alloyed in the fibers, or two or more types of fibers may be used without significantly impairing physical properties. And, the TP woven fiber-existence material is made of fiber-reinforced material with 100%
In terms of volume %, at least 20 volume % is required, preferably 30 volume % or more.

However, for purposes such as coloring, adhesion, anti-oxidation, and increasing the smoothness by enriching the resin only on the surface,
This does not apply when a matrix such as a TP film or a thermosetting resin is used in combination.

In the present invention, one or more inorganic or organic fillers, whiskers, pigments, plasticizers, etc. may be included as necessary in order to improve rigidity, fluidity, coloring, antioxidant, lubricity, and other properties. good.

If the length of the short fibers is long, a good appearance with less noticeable fuzz of the TP short fibers can be obtained, but it becomes difficult to mix the fibers uniformly. When the length is short, it is easy to mix the fibers, but the fuzz of the TP short fibers becomes noticeable and they tend to come off easily during handling.

Therefore, it is necessary to select the TP short fibers in consideration of their thickness and ease of entanglement with the reinforcing long fibers. Specifically, the length is about 600 meters from IM, preferably 15 meters from 3M.
It is 0 Peng.

In the present invention, "mixed fiber J" is calculated as follows.
This means that the degree of blending in the cross-sectional direction is 50% or less. In other words, a mixed fiber bundle with a yarn length of 10 m,
When observing the plane cut at right angles at at least 10 places evenly along the yarn direction, the single fibers of the reinforcing fibers are surrounded by convex polygons so that no TP short fibers are included inside, and the same -
In the cross section, the number of single fibers in the largest group in the enclosed polygon is used as the numerator, and the number of single fibers in the reinforced long fiber bundle before mixing is used as the denominator, and the average value is calculated as %.
Expressed as A state in which the degree of blending in the cross-sectional direction calculated in this way is 50% or less is called mixed fiber, and the preferable blend is 20%.
% or less, most preferably 10% or less.

Furthermore, "degree of blending in the longitudinal direction" is used as another measure to indicate the state of blending. The degree of blending in the longitudinal direction is defined as 50c+ when observing a 10m long fiber bundle with the naked eye.
Select 10 locations with poor fiber blending at intervals of a or more, measure the fiber blend in each cross-sectional direction, and calculate the average value. The ratio obtained by dividing this average value by the above-mentioned cross-sectional fiber mixing degree is defined as the longitudinal fiber mixing degree. - The above ratio tends to increase as the degree of blending in the cross-sectional direction increases in boat fishing. Although it is difficult to specify a preferred ratio,
For example, in the case of a cross-sectional direction blending degree of 20%, the preferred ratio is 2 or less, more preferably 1.5 or less, and in the case of a cross-sectional direction blending degree of 10%, the preferable ratio is 4 or less, more preferably 2 or less.

Generally, composites for reinforcing fiber materials using TP woven fibers are
Since the polymer constituting the TP woven fiber is a polymer, it has a high viscosity during melt molding, and it is necessary to uniformly disperse it in the reinforcing fiber in advance. The reinforcing fiber material loses its integrity significantly because the reinforcing fiber material is easily destroyed and the fracture progresses from there.

It should be noted that a large degree of "mixture in the longitudinal direction" tends to appear periodically due to twisting, etc., and judgment with the naked eye is more reliable. Furthermore, if the fibers have the same color and are difficult to distinguish with the naked eye, this can be easily done by using a known method such as dyeing only the TP woven fibers.

"Bulky property" as used herein is a property indicating how thin a plate obtained by melting, compressing and cooling the composite of the present invention can be made.

In general, long fiber reinforced materials are strong in the reinforcing fiber direction, but
It is extremely weak in the right angle direction, so it is used by stacking them at different angles and melting them together.

Additionally, during the post-processing cutting and hole-drilling process, a cloth-like woven material is used only on the surface to prevent reinforcing fibers from protruding from the cut surface. For these materials, it is very difficult to reduce the overall weight and use a large number of rolls due to cost, since the reinforcing fibers have a high elastic modulus and do not stretch and break easily. Therefore, attempts are being made to increase the spreadability and thin the fiber bundles with the same number of fibers (for example,
Japanese Patent Publication No. 56-43435). The short fiber mixed reinforcing fiber bundle of the present invention is a material that can meet these demands.

Furthermore, as an unexpected effect, a laminate with high interlayer adhesive strength can be obtained. This is probably because the TP short fibers are not perfectly aligned in the direction of the reinforcing fibers, and become random to some extent when melted, cooled, and hardened.

The short fiber mixed reinforced long fiber bundle of the present invention can be obtained by the following method. First, conventionally known thermoplastic resin (TP) fibers are cut into short fibers by cutting or tearing with a cutter, and the fibers are added to a liquid and dispersed.Next, reinforced fibers that have been opened in advance is continuously supplied to the liquid, the liquid in which the TP woven fibers have been dispersed is poured into the liquid, and the reinforcing continuous fibers are gently pulled downstream so as not to break. The liquid is separated and wound up through a coated wire mesh, and the adhering moisture is then dried to obtain a short fiber mixed reinforced long fiber bundle.

In order to produce reinforced fiber bundles in which the elongation of the single fibers in the reinforced long fiber bundle is large and there are almost no single fiber breaks, or reinforcing fiber bundles that can be used even if there are a few single fiber breaks, there is an alternative method. It is also possible to adopt a method in which high-speed air that causes the TP short fibers to float and flow is blown into the reinforcing fiber bundle and the gas is separated using a wire mesh or the like.

Note that the object of the present invention can also be achieved by wrapping the short fibers with conventionally known fibers so that the short fibers do not easily fall off from the short fiber mixed reinforced long fiber bundle.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

Example 1 A water tank with a rll of 60 cm, a length of 2 m, and a depth of 50 cm was filled with water to about 80%, and reinforced long fibers of Hi-Carboron 3kf yarn (PAN-based carbon fiber, number of single fibers: 3000) manufactured by Asahi Kasei Carbon Fiber Co., Ltd. The bundle is fed through a roller, and water is jetted from 10 pairs of opposing nozzles perpendicular to the direction of the yarn, and the position of the nozzle and the amount of water jetted are adjusted so that turbulent flow occurs in the space containing the fiber bundle. was adjusted so that the fibers flow downstream of the liquid flow in an open state.

Next, polyether ether ketone (manufactured by Imperial Chemical Industries, trade name: Pict 1/Tux) was melt-spun to obtain a 770 denier/72 filament multifilament.

A large number of these multifilaments were collected and cut into a length of 811 Ifl using a molded guillotine cutter manufactured by Onoda Manufacturing Co., Ltd. to obtain TP short fibers. Next, the TP short fibers were added to water and dispersed. This dispersion liquid was evenly and continuously added to the portion where the reinforced long fiber bundle was opened.

Next, this reinforced long fiber bundle was taken downstream, passed over a 200-mesh wire mesh coated with Teflon to drain water, and when the yarn was wound, the TP short fibers were uniformly mixed. A short fiber mixed reinforced long fiber bundle was obtained. The carbon fiber content of this short fiber mixed reinforced long fiber bundle was extracted and measured with concentrated sulfuric acid, and was found to be 62.7% by volume.

Furthermore, we took out 10 m of this thread, solidified and fixed it with epoxy resin at IO points at 1 m intervals, cut it with a diamond cutter, polished it, and observed the cross section in detail with an optical microscope at 100x magnification to examine the degree of fiber blending in the cross-sectional direction. , 6.5%. Furthermore, 10 m of yarn was taken out, and samples were taken from 10 locations at intervals of 50 cm or more where the carbon fibers were likely to be clumped together and the fibers would not mix properly. In the same way, when we measured the degree of blending in the cross-sectional direction, it was 10.5%, and the degree of blending in the longitudinal direction was 1.6 times.When weaving with a good blending degree, we found that the short fibers had some waves. However, there were no problems such as breakage of single fibers of the reinforced long fibers or difficulty in winding them into rolls (fabric with high bulkiness and properties was obtained).

Next, one sheet of this fabric was heated and melted at 420'C under a pressure of 15 kg/crA for 10 minutes under vacuum, and when taken out after cooling, the fabric weight was 120 g/n ((weight per square meter of carbon fiber, resin (The weight is not included.) A thin plate was obtained.In addition, a laminate was obtained by stacking 8 pieces of the above-mentioned fabric and press-molding it.When the temporary strength of this was measured, the tensile strength was 45 kg/m11'' Met.

A laminate was molded in the same manner as above except that the pressure was increased to 100 kg/c-, and the interlaminar shear strength was measured according to ASTM D-2344 and found to be 9.0 kg/mm.

Comparative Example 1 The same carbon fibers and polyetherimide continuous fibers used in Example 1 were placed in the same water tank as in Example 1 at a feeding rate 3% faster than the take-up rate to create a gentle tension state in order to mix well. The position and ejection amount of the 10 pairs of nozzles were adjusted so that the yarns were mixed by continuous feeding, and the fibers were wound downstream and dried to obtain a fiber bundle in which continuous long fibers were mixed together.

The carbon fiber content of this yarn was 62.7%.

Further, 10 m of this yarn was taken out, 10 points were selected at 1 m intervals, and the fiber blending degree in the cross-sectional direction was examined in the same manner as in Example 1, and it was found that the fibers were blended relatively well at 9.5%. However, when closely observed with the naked eye in the longitudinal direction,
There are areas where the fibers are not mixed at approximately every 60 cm, and we selected 10 areas where the fibers were most likely to be mixed and examined the degree of fiber mixing in the cross-sectional direction.The result was 60%, and the degree of fiber mixing in the longitudinal direction was 663 times higher. , a rather heterogeneous mixed cane morphology was found.

Next, when flat iso cloth was woven from this fiber bundle, the first 100 meters of weaving turned out to be a relatively high-quality #Ia fabric, but there was some fuzz from broken polyetherimide single fibers on the roll. As soon as I wrapped it around, the whole thing got tangled up and the thread broke.

The initially obtained fabric was weighed 15 kg in the same manner as in Example 1.
The material was heated and melted at 420° C. for 10 minutes under a pressure of /c+fl, and taken out after cooling, to obtain a tentative basis weight of 150 g/rrf. When we measured the strength of a laminate made by stacking six of these plates and forming them under pressure, the tensile strength was 32 kg/mm.
Met. In order to investigate the cause of the low strength, we observed it under a microscope and found that there were many voids, and it was assumed that the cut was made from these areas.

Therefore, the void is 100 kg/c
When it was molded under high pressure of U and its strength was measured, it was 44k.
A plate with a tensile strength of “g/mm” was obtained.

Next, the interlaminar shear strength of the laminate molded under high pressure of 100 kg/cJ was measured in the same manner as in Example 1, and it was found to be 7.0.
kg/ml12.

〔Effect of the invention〕

When the short fiber mixed reinforced long fiber bundle of the present invention is used to make composite materials, it is possible to obtain slopes with higher strength under easier molding conditions than with conventional materials, and also to make thin plates. Therefore, it can be used in a wider range of applications and has high industrial value.

Claims (1)

[Claims] 1. A short fiber mixed reinforced long fiber bundle characterized in that thermoplastic resin short fibers are mixed in the reinforced long fiber bundle.