JPH0325340B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fiber-reinforced composition and a fiber-reinforced molded article containing a thermoplastic resin. BACKGROUND OF THE INVENTION Methods are known for producing fiber reinforced structures by drawing glass fiber tows or rovings through a bath of low viscosity thermoset resin to impregnate the fibers. This structure is often cured by heating. Such a method is known as pultrusion. Although such methods have been known for at least ten years, they have not been used to any degree of expertise for the production of thermoset resin-impregnated structures. The reason for this is that it is difficult to wet the fibers when drawn through a viscous molten resin. The resulting product has unacceptable properties as a result of poor wetting. The efficiency of a particular method for wetting fibers and thereby providing the basis for making full use of the very high level of physical properties inherent in continuous fibers, e.g. glass fibers, is such that this method theoretically It can be evaluated by measuring the extent to which it provides a product with a flexural modulus that reaches the achievable flexural modulus. The theoretically achievable flexural modulus is calculated using the following simple rule for mixtures: E _L = V _f E _f + V _n E _n where E _L is the longitudinal modulus of the composition; V _f is the volume fraction of the fiber, E _f is the flexural modulus of the fiber, V _n is the volume fraction of the matrix polymer, and E _n is the flexural modulus of the matrix polymer. Using melts of conventional high molecular weight thermoplastic polymers for impregnating continuous rovings does not allow high levels of flexural modulus to be obtained. for example,
U.S. Pat. No. 3,993,726 discloses an improved method of impregnating a continuous roving in a crosshead extruder under high pressure, drawing the roving through a die, and cooling and forming the roving into a void-free molded article. ing. The product obtained with polypropylene in Example 1, for a glass fiber content of 73% by weight, was only about
6GN/m ² , that is, the theoretically achievable value.
It has been shown to have a flexural modulus of 20%. It has now been discovered that it is possible to produce materials with levels of flexural modulus that approach those theoretically achievable. The structure is therefore produced by a continuous process and contains at least 30% by volume of the structure of reinforcing filaments extending in the longitudinal direction of the product;
consisting of a thermoplastic polymer and a reinforcing filament, characterized in that the flexural modulus of the structure, measured according to ASTMD 790-80, is at least 70%, preferably at least 80%, of the theoretically achievable flexural modulus A fiber reinforced structure is provided. The interlaminar shear strength of these structures is greater than 10 MN/m ² , preferably 20 MN/m ² . Preferred thermoplastic polymers for use in the present invention are crystalline polymers with a melting point of at least 150°C and amorphous polymers with a glass transition point of at least 25°C. For optimal stiffness, the thermoplastic polymer should have a flexural modulus of at least 1 GN/m ² , preferably at least 1.5 GN/m ² . Fiber-reinforced structures can be produced by various methods that allow for good wetting of continuous, aligned filaments. In one of these methods, a plurality of successive filaments are drawn through a melt of a thermoplastic polymer having a melt viscosity of less than 30 Ns/m ² , preferably between 1 and 10 Ns/m ² , so that the filaments are exposed to the molten polymer. A method for producing a fiber-reinforced composition is provided, characterized in that the filaments are aligned in the direction of pull. If desired, the impregnated filament can be consolidated into a fiber-reinforced polymorphic structure. The viscosity of thermoplastics varies with shear rate, decreasing from a nearly constant value at low shear rates. In the present case, the viscosity at low shear rates is used (typically Newtonian viscosity is used).
This is conveniently measured using a capillary viscometer using a die 1 mm in diameter and 8 mm in length, with melt viscosities ranging from 13 ³ to
Measured at shear stresses in the range 10 ⁴ N/m ² . Surprisingly, such polymers
Despite the fact that the molecular weight is lower than is normally considered appropriate in the field of thermoplastic polymers to achieve satisfactory physical properties, the reinforced compositions exhibit exceptionally good physical properties. When producing the thus reinforced cured plastic polymer compositions with cyclical properties by pultrusion methods, the viscosity of the thermoplastic prepolymer in the impregnating bath is typically 1 Ns/m ² in order to obtain good wetting of the fibers. It is smaller. This low viscosity can be used because
The prepolymer is subsequently converted into solid form by thermosetting methods. In contrast, thermosetting polymers are usually fully polymerized solid materials and can only be obtained in liquid form by heating and melting thermoplastic polymers. However, the melt viscosity of common high molecular weight polymers with acceptable physical properties usually exceeds 100 Ns/ ^m2 . With pultrusion processes using melts of such high viscosity, it is not possible to obtain adequate wetting of the fibers. Although it is possible to reduce the melt viscosity to some extent by increasing the temperature of the melt, the reduction in viscosity that is possible below the decomposition temperature of the thermoplastic polymer is usually insufficient. High viscosity products can be obtained by properly wetting the fibers in pultrusion processes using thermoplastic polymers with sufficiently low molecular weights to provide sufficiently low melt viscosities. Therefore, also drawing a plurality of successive filaments through a melt of a thermoplastic polymer whose melt viscosity is less than 30 Ns/m ² , preferably between 1 and 10 Ns/m ² to wet the filaments with molten polymer. Provided is a fiber-reinforced thermoplastic composition obtained by the method of the present invention, characterized in that the filaments are aligned in the direction of pull. The fiber reinforced structure produced should have a void content of less than 15%, preferably less than 5%. The term "continuous fiber" or "multiple continuous filaments" refers to fibers of sufficient length to be drawn through a molten polymer without breaking at a frequency that would make the process unfeasible under the processing conditions employed. means a textile product in which the fibers are of sufficient length to form rovings or tows. Suitable materials are glass fibers, carbon fibers, juute and high modulus synthetic polymer fibers. In the latter case, it is important to satisfy the condition that the polymer fibers have sufficient strength to be able to be drawn through the polymer melt without breaking which would disturb the process. In order to have sufficient strength to be pulled through an impregnated system without fracturing, the majority of the continuous fibers in a textile must be pulled through the molten polymer with the majority of the continuous fibers aligned. It should lie in one direction so that it is taut. Textile products such as pine that are composed of randomly arranged continuous fibers are not suitable for use in the present invention unless they form part of a fibrous structure in which at least 50% by volume of the fibers are aligned in the direction of pull. Appropriate. The continuous fibers can be in any form with sufficient integrity to be drawn through the molten polymer, but conveniently substantially all of the fibers are aligned along the length of the bundle. Consists of bundles of individual fibers or filaments (hereinafter referred to as "rovings"). Any number of such rovings can be used. In the case of commercially available glass rovings, each roving could consist of up to 8000 or more continuous glass filaments. Carbon fibers containing up to 6000 carbon fibers or more can be used.
Cloths woven from roving are also suitable for use in the present invention. The continuous filament may have conventional surface sizes, especially those designed to maximize bonding between the fibers and the matrix polymer. In order to achieve the high levels of flexural modulus possible with the use of the present invention, it is necessary that as much of the surface of the continuous filament as possible be wetted with molten polymer. Thus, when a fiber is comprised of multiple filaments, the surfaces of the individual filaments that make up the fiber must be wetted for optimum effectiveness. surface sizing agent for filament,
That is, when treated with a fixer, the polymer will not come into direct contact with the surface of the fiber or filament due to the intervening sizing agent. However, as long as good adhesion is achieved between the fiber and the size and between the size and the polymer,
The products of the invention have high flexural modulus, and sizing agents will generally enhance the resulting properties. The thermoplastic polymer used in the method described above has a melt of less than 30 Ns/ ^m2 , preferably
It can be any polymer that melts to form a cohesive mass as long as it has a viscosity of less than 10 Ns/m ² . To achieve acceptable physical properties in toughened compositions, the melt viscosity must be
Preferably it exceeds 1 Ns/m ² . As indicated, the selection of polymers within the required melt viscosity range depends primarily on the molecular weight of the polymer. Examples of suitable polymers are thermoplastic polyesters, polyamides, polysulfones, polyoxymethylenes, polypropylenes, polyarylene sulfides, polyphenylene oxide/polystyrene blends, polyetheretherketones and polyetherketones. Although various other thermoplastic polymers can be used in the method of the present invention, polymers such as polyethylene will not provide such high strength compositions. In the process of impregnating the fibers of the roving, in addition to using a polymer of appropriate melt viscosity to produce adequate wetting, it is necessary to maximize penetration of the melt into the roving. This separates the rovings into individual constituent fibers, for example by applying an electrostatic charge to the rovings before they enter the molten polymer, or preferably by spreading the rovings while they are in the molten polymer to separate them into constituent filaments. This can be done by separating as much as possible. This is conveniently accomplished by passing the roving under tension over at least one, and preferably several, spreader surfaces.
Applying further work to the separated and polymer-impregnated fibers, for example by consolidating said separated fibers by drawing an impregnated roving from the melt through a die,
Wetting increases further. This die can have the desired profile for the impregnated roving, or the impregnated roving can be passed through an additional sizing die while the polymer is still flowable. Surprisingly, it is advantageous to cool the die to achieve satisfactory sizing and smooth passage through the die. When the impregnated roving leaves the bath in the form of a flat sheet, further work can be added by passing this sheet between a pair of rollers. The speed at which the roving can be drawn through the impregnation bath depends on the requirement that the individual fibers should be properly wetted. This will depend, to a large extent, on the length of the path of molten polymer through the bath, and in particular on the degree of mechanical spreading action that the roving undergoes in the bath. The speeds that can be achieved in the method of the invention are comparable to those that can be achieved in thermoset pultrusion processes. This is because pultrusion methods are limited by the time required to complete the necessary chemical reactions after the impregnation step. In a preferred embodiment, the spreader surface over which the rovings are drawn to separate the rovings has an external heat input to heat the spreader surface to a temperature above the melting point of the particular polymer to be used to impregnate the rovings. . By this means, the melt viscosity of the polymer in local areas of the surface of the spreader can be maintained at a significantly lower value than the polymer in the majority of the impregnating bath. The advantage of this method is that a very small proportion of the polymer can be raised to a relatively high temperature, thereby obtaining a low impregnation viscosity with minimal risk of decomposition of the major proportion of the polymer in the bath. There is a particular thing. As a result, the polymer feed in the bath is continuously replenished, greatly reducing the problems arising from the fact that some polymers may remain in the bath for an almost unlimited period of time during a given treatment period. be done. Thus, some of the polymer present at the beginning of the treatment period may still be present at the end of the treatment period. Despite this long residence time in the bath, such polymers undergo a less severe thermal history than if the entirety of the polymer in the bath were exposed to high temperatures throughout the bath to obtain a low viscosity. Probably. A further advantage of the local heating method is that less thermally stable polymers can be used. Furthermore, the low degradation resulting from the low total thermal history allows the use of high temperatures locally to produce melts of low viscosity, thus allowing the use of high molecular weight polymers. The feed of polymer to the impregnation bath can be in the form of a polymer powder that is melted in the bath by an external heating element or by a heated spreader surface located internally, or alternatively, is added to the bath. The molten polymer can be fed, for example, in a conventional screw extruder. When the bath is equipped with a heated spreader surface, the polymer melt delivered from the extruder should be at as low a temperature as possible to minimize thermal decomposition. The use of molten feeds is easy to start, provides excellent temperature control, and
And it has the advantage that unmelted polymer lumps, which give rise to various processing problems, especially when producing very thin structures, are avoided. The impregnated fiber product can be drawn through a means for compacting the product, such as a sizing die. The temperature of the die was found to have a significant effect on the method. Although it would be expected that a hot die should be used to minimize friction in the die and promote solidification, a die held at a temperature above the melting point of the polymer used will prevent the product from dying. It has been found that when pulled through, an extraordinary sticky slip behavior occurs. It has been found that it is preferable to use a cooled die and to ensure that the surface temperature of the pultruded part entering the die is no more than 20°C above the softening temperature of the polymer. "Softening temperature"
means the lowest temperature at which the polymer can be sintered. This can be accomplished by blowing air onto the race in the passage between the impregnation bath and the die and/or by spacing the die from the impregnation bath. If the pultruded part gets too hot, the polymer will be squeezed out as the product enters the die. This leaves deposits at the entrance to the die that can accumulate and streak the pultruded part as it passes through the die. The pultruded part should not be cooled below the softening point of the polymer. This is because it is too difficult to shape the product with a sizing die. The dimensions of the fiber reinforced product can be varied as desired. Thin sheets can be produced by separating the fibers of a number of rovings by passing them over the spreader surface so that the fibers form a band in continuous relationship. . When a die is used to compact the fibers, the structure will take the form of the cross section of the sizing die. This can form articles of any required thickness, for example thicknesses or profiles from 0.25 mm to 50 mm. When the compacting means consists of a nip formed from at least one pair of rotating rollers, sheets having a thickness of less than 0.05 mm can be produced. In other methods of producing fiber-reinforced structures, it has been found that satisfactory wetting can be achieved even when the thermoplastic polymer used has a melt viscosity significantly above 30 Ns/m ² . Accordingly, a plurality of continuous filaments is tensioned and aligned to form a band of continuous filaments, which band is placed over a heated spreader surface, forming a nip between the band and the spreader surface. The supply of thermoplastic polymer is maintained in the nip in such a way that the temperature of the spreader surface forms a polymer melt of a viscosity capable of wetting the continuous filament as it is drawn over it. Provided is a method for producing a fiber-reinforced composition characterized in that the fiber-reinforced composition has a sufficiently high The polymer melt at the tip of the nip preferably has a viscosity of less than 30 Ns/ ^m2 , but the high back tension on the filament to be fed to the spreader surface ensures that impregnation of the polymer in the nip area is favorable. , thereby allowing the production of well-impregnated bands at viscosities significantly higher than 30 Ns/m ² .
This method thus provides a means to maximize the molecular weight of polymers that can be used in thermoplastic polymer pultrusion processes. In one embodiment of this method, the continuous filament is most appropriately tensioned and aligned by drawing it from a roll or reel onto a series of spreader surfaces, such as the surfaces of rods. This allows the bundle of filaments to be spread out into individual filaments as far as possible and under considerable tension. These filaments are guided to form a continuous filament band as they pass over the heated spreader surface. The shape of the spreader surface and the contact angle between the filament and the spreader surface are such that a nip is formed between the band and the heated spreader surface. Thermoplastic polymer powder is fed into the nip and the heated spreader surface is maintained at a temperature sufficient to melt the thermoplastic polymer. The melt impregnates and wets the fibers of the band as it passes over the heated spreader surface. The method includes providing at least one additional heated spreader surface with a second band of at least partially impregnated fibers.
This can be modified by forming a nip which allows an additional supply of polymer to be impregnated into the band of fibers. Either surface of the partially impregnated band can also be used to form the working surface of the nip. The amount of polymer in the reinforced structure is largely controlled by the tension applied to the band and the length of the path through which the band contacts the heated spreader surface. Thus, when the band is under high tension and in substantial area contact with the spreader surface, such that when the band is pressed strongly against the spreader surface, the polymer content of the reinforcing structure is reduced under low tension/short contact. would be less than under passage conditions. The heated spreader surfaces and, when used, subsequently heated or cooled surfaces used to improve impregnation or to improve surface finish are preferably in the form of cylindrical bars or rollers. For example, the first impregnated surface can be a freely rotating roller that is rotated by a band at the speed of the band;
As a result, abrasion of the fibers prior to impregnation or sizing with the melt can be reduced to a minimum. When the first roll rotates (freely or driven) in the direction of fiber movement up to the speed of the fibers, as the free fibers accumulate on the band, they cannot be carried through the system. observed. This self-cleaning effect is particularly effective in preventing fiber buildup on the first roll that could cause the band to split. After the band picks up some molten polymer, preferably after additional molten polymer is provided by a second freely rotatable heated surface on the other side of the band, the fibers tend to undergo abrasion. very little and can be subjected to treatments to improve fiber wetting. Thus, the polymer-containing band has at least one
can be passed over two rollers to increase local work input to the band and maximize wetting. In general, the degree of wetting and the speed of the method can be increased by increasing the number of surfaces on which work input is present. Another advantage of using bands of fibers to form the nip over methods that require the use of batches of molten polymer is that it reduces the risk of decomposition. Thus, since a relatively small amount of polymer is present in the nip between the band of fibers and the spreader surface, large amounts of polymer do not have to be kept at high temperatures for long periods of time. A scraper blade can be installed at the location where the polymer is fed into the nip to remove excess polymer that may accumulate and undergo thermal decomposition during processing. When the product of the above process is required as a thin reinforced sheet, the product produced by impregnation in the nip is further processed by passing it over or between additional heated or cooled rollers. can be used to improve impregnation or improve the surface finish of the sheet. A thin sheet tends to curl when one side of it contains more polymer than the other side.
This can be avoided by placing an adjustable heated scraper close to the last roller in the roller system to remove excess polymer on the surface of the sheet. The scraper bar should be at a temperature just above the melting point of the polymer. For example, in the case of polyetheretherketone, which reaches a temperature of about 380°C in the impregnation zone, the temperature of the scraper bar should be about 350°C. The impregnated band can then be further processed depending on the intended shape and purpose of the final product. The separated filaments in the impregnated band can be drawn together through a die, for example, into a significantly larger profile than the impregnated band. A limited amount of shaping can be carried out in such a die to obtain a shaped profile. The impregnated product of the foregoing process can be rolled into rolls for continued use in molding processes requiring continuous product or cut into lengths for continued molding. Continuous lengths can be created, e.g. by wrapping the heat-softened product around the fore, or e.g.
Mat can be woven from tapes or strips of the product and used to make articles. The impregnated product can be chopped into pellets or granules with aligned fibers having a length of 3 mm to 100 mm. These can be used in conventional molding or extrusion methods. When using glass fibers, the fiber content of the product of the invention should be at least 50% by weight of the product to maximize the physical properties of the product.
The upper limit on fiber content is determined by the amount of polymer required to wet the individual fibers of the roving. Generally, it is difficult to achieve good wetting with less than 20% polymer by weight;
Very good results can be obtained by incorporating 30% by weight of polymer into the fiber reinforced composition according to the method of the invention. The products of the present invention, formed by the process of impregnating a band of continuous rovings in the nip formed by the band and the heated spreader surface, are typically stretched through the impregnated system as a band or sheet of material. Will. This yields intermediates useful in many applications. Thin bands or sheets, ie, thicknesses less than 0.5 mm and greater than 0.05 mm, are particularly useful and flexible. The tape is tabby or satin (these terms are used in the textile field and are referred to in the Encyclopedia Britannica's “Weaving
Satin weave provides particularly good products, as shown in the Examples herein. Exceptionally high performance textiles are obtained using tapes produced according to the invention and whose width is at least 10 times the thickness.One important application is as a thin reinforced sheet. The sheet is made from a number of plies of reinforced sheets, the reinforcement of each layer being oriented in a selected direction in the plane of the layer, and the layers being compressed at a temperature sufficient to fuse the polymers of the layer. The layer can be used as a flat sheet that can be formed in a mold during or after the fusing process, or the layer can be wrapped around or on a forming mandrel. After a molding and then fusing step, an article having the shape of a mandrel can be obtained. The reinforcing filament is wound onto the molding mandrel and a layer of polymer film is interposed between the layers of filament, followed by a polymer film. The production of reinforced molded parts by fusing films is described, for example, in British Patent No. 1485586.
It is already known as disclosed in No. The present invention is superior to such methods. The main advantages are the avoidance of the use of high cost preformed polymers, the avoidance of preparing films of various thicknesses since the polymer content can be controlled by band tension, and the method of the present invention. This is an advantage derived from the continuous nature of The pultruded articles of the invention are likewise suitable for selectively reinforcing articles molded from polymeric materials by chopping them to appropriate dimensions. In this method, at least one preformed element consisting of a product according to the invention is placed in a mold to reinforce selected portions of the finished molded article, and a polymeric material is placed around the in-situ reinforcement. Mold to form a shaped article. The present invention not only allows fiber reinforcement to be placed in molded articles to obtain maximum effectiveness with respect to the stresses to which the molded article is subjected in use, but also allows for the production of such high strength articles in an alternative manner. Overcome the machining problems faced when. In particular, this method can be used to produce such reinforced articles by a high-throughput injection molding process using common thermoplastic polymers with melt viscosities of 100 Ns/m ² or higher. In some applications, a preformed element is used at a temperature at which it is flexible, so that
It would be advantageous to make it easier to place the preformed element into the mold, for example by wrapping it around the insert of the mold. The molding method used can be any method in which a molded article is molded from a polymeric material in a mold.
The polymeric material can be a thermoplastic material that is introduced into the mold as a melt, as in injection molding methods, or as a powder, as in compression molding methods. The term "compression molding"
It includes a method of compacting a polymer powder without melting and subsequently sintering this "green" molded part out of the mold. The thermoplastic polymer material formed in the mold is
It can also be induced by introducing monomers or partially polymerized media into the mold, for example under the action of heat or chemical activators or initiators, which are held until complete polymerization. can. Preferably, the polymer formed around the preformed insert is the same as, or at least compatible with, the polymer used to impregnate the preformed insert. The impregnated product obtained from the above method has reinforcing fibers of at least 3 mm, preferably at least 10
It finds particular utility when chopped into pellets or granules with a length of mm. These products can be used in common molding processes such as injection molding and are superior to prior art products in pellet form. This is because the fiber length in the pellets is retained to a much greater extent than when using prior art products. This greater fiber length retention is
It is believed that the protection imparted to the individual reinforcing filaments in the products of the present invention is largely a result of the superior wetting by the polymer that results from the use of the aforementioned method. This aspect of the invention is of particular importance. Because this strengthens the work of the goods,
For example, it can be formed in injection molding, which uses screw extrusion to melt and homogenize the feed material, resulting in a surprisingly high degree of fiber length retention and ultimately improved physical properties. It is. The product of the invention thus makes it possible to obtain shaped articles from a molding process using screw extrusion, which shaped articles contain at least 50% by weight, preferably at least 70% by weight of fibers with a length of at least 3 mm. do. This is done by melting and homogenizing the reinforced product of the invention in short lengths, i.e. 2 to 100 mm, which is considerably longer than normally obtained from commercially available reinforced products. Another method of forming the article is by calendering. For example, sheet products can be manufactured using this method. Products suitable for injection molding can be used directly or
Alternatively, it can be blended with pellets of other thermoplastic products. These other products can be the same polymer except for a higher molecular weight, or they can be different polymers so long as the presence of a different polymer does not adversely affect the overall balance of properties of the composition. Other products may be unfilled polymers or may contain particulate or fibrous fillers. Reinforced molding powder produced by conventional methods, i.e. length approx. 0.25
Blends with materials containing molding powders containing up to mm reinforcing fibers are particularly suitable. This is because the overall reinforcing fiber content of the blend can be kept high, although the short reinforcing fibers do not contribute as effectively as the long fibers present from the products of this invention. The chopped form of continuous pultrusion is also very useful as a feedstock as described in co-pending British Patent Application No. 8101822. In the method of said British patent application, the fiber-reinforced molded article is made by passing a composition comprising a curable fluid as a carrier for fibers of a length of at least 5 mm through a die, whereby when the extrudate leaves the die; , relaxing the fibers and expanding the extrudate to form an open fibrous structure in which the fibers are randomly distributed, and compressing the produced porous structure while the carrier is in a fluid state. It is manufactured by making it into a molded product. The term "hardenable" means that it can "set" the fluid into a form such that it holds the fibers in the random orientation that occurs during extrusion. Thus, for example, the curable fluid can be a molten thermoplastic material that is extruded in the molten state and then solidified by cooling until it freezes. Preferably, the expanded extrudate is directly extruded into a mold chamber having means for compressing the porous extrudate into a molded article, and after the extrudate has been compressed into a molded article, the extrudate is allowed to solidify; Or solidify. Extrudates formed in this manner contain randomly dispersed fibers, and the orientation of the fibers in the molded article itself may result from compression. This method can be used with high fiber loadings, ie 30% by volume fiber. Since fiber breaks occur very little, it is possible to obtain molded articles with exceptionally high strength, measured in all directions of the product. At least 5 pultruded products of the invention
Preference is given to pellets obtained by chopping into lengths of mm, preferably 10 mm. The upper limit is determined by the extent of problems encountered in the material fed to the extruder that melts the product. at least
Lengths up to 50 mm can be used, but the advantages of longer fiber lengths are partially compromised as the amount of fiber that breaks increases with longer lengths. To achieve adequate wetting of the roving, relatively low molecular weight polymers, e.g. 30Ns/
It is necessary to use polymers with a melt viscosity of less than ^m2 , preferably less than 10 Ns/ ^m2 , and it is surprising that such products have such a high level of physical properties. However, the present invention does not preclude a subsequent processing step to increase the molecular weight of the polymer in the composition by known methods. Such techniques include solid state polymerization in the case of condensation polymers, the use of crosslinking agents or irradiation techniques. When using crosslinking agents to increase the molecular weight, it is necessary to mix them homogeneously into the composition. This is only possible if they are already present during impregnation, but in such cases care must be taken that they are not activated before the wetting step is complete. The present invention and related inventions will be further described with reference to the following examples. Example 1 Using a copolymer of polyethylene terephthalate in which 20% by weight of the terephthalic acid has been substituted with tri-isophthalic acid and having the intrinsic viscosity values listed in Table 1, polymerization is carried out in a bath at a temperature of approximately 290°C. A melt was prepared. A roving of glass containing 16,000 individual filaments is passed through the molten polymer over one spreader placed in the bath giving a residence time of 30 seconds in the bath.
It was pulled at a speed of cm/min. The impregnated roving was drawn through a 3 mm diameter die in the wall of the bath and then cooled. The viscosity of the melt and the intrinsic viscosity in the polymer feedstock and reinforced compositions were measured. The degree of wetting and void content of the fibers was evaluated by comparing the weight of a fully wetted length of impregnated product to the same length of product of unknown degree of wetting. A completely wet control material is obtained by pultrusion of a low viscosity melt at a very slow speed so that a completely transparent product is obtained. A fully wetted standard is thus considered to be a sample that is transparent and produced under conditions that optimize the parameters suitable for wetting. The values of the degree of wetting listed in the table are derived from the following relational expression: Degree of wetting = M ₂ - M ₁ / M ₀ - M ₁ × 100% where M ₀ is the nominal unit of the transparent sample. M ₁ is the mass per unit length of the glass, and M ₂ is the mass per unit length of the sample to be evaluated. Void content is the percentage of wetting
Obtained by subtracting from 100%. The strength of the product was evaluated by measuring the force required to bend and break a 3 mm rod sample placed across a 64 mm span. The results obtained are listed in Table 1.

Table: Example 2 The polymer used in Example 1 having an intrinsic viscosity of 0.45 dl/g was evaluated over a range of melt temperatures and tensile pass rates. The results obtained are listed in Table 2 below.

[Table] * Excessive destruction occurred at this temperature.
Example 3 Melt viscosity of 6Ns/ ^m2 at 280°C
The PET homopolymer was pultruded as described in Example 1 using glass fibers constructed from 17 μm diameter filaments at 280° C. using a single spreader rod and a line speed of 30 cm/min. A pultruded rod having a diameter of approximately 3 mm was obtained. The glass content of the product was varied by varying the number of strands in the roving fed to the bath. Flexural modulus and force at failure were determined as a function of glass content using a span of 64 mm.

TABLE (5 measurements at each location, numbers in brackets indicate standard deviation) These results show an approximate plateau of modulus and strength in the area 50-65% by weight glass. Example 4 Common grade polypropylene has a viscosity at low shear rates of over 100 Ns/m ² and is not processed well by pultrusion. for example,
The melt viscosity of “Propathene” HF11, a polypropylene homopolymer, is approximately 3000 Ns/m 2 at 280°C or approximately 3000 Ns/m ² at 230°C at low shear rates.
It is 10000Ns/ ^m2 . To make a polymer suitable for pultrusion, “Propathene” HF11 was combined with 0.1% calcium stearate and 0.1% “Irganox” 1010.
and 0.5% “Luperco” 101XL (“Luperco”
101XL is an organic peroxide dispersed with calcium carbonate) to allow decomposition to occur. This formulation was pultruded using a single spreader at 30 cm/min at temperatures of 230°C and 290°C. At 230° C. (melt viscosity 30 Ns/m ² ) wetting was poor. 290℃ (melt viscosity 17Ns/
m ² ), wetting was moderate. Example 5 A sample of “Victrex” polyethersulfone with a relative viscosity of 0.3 was pultruded with the glass fibers used in Example 3 using a single spreader bar at 21 cm/min (30 Ns/m A moderately wet extrudate was obtained (melt viscosity of ² ). This caused the sample to wet poorly at low temperatures and high viscosities. Example 6 The wetting of the rovings is clearly influenced by the number of spreader bars, and under the same operating conditions an increase in linear velocity can be carried out for any degree of wetting by increasing the number of spreaders. The glass fiber used in Example 3 was 280
pultrusion using PET homopolymer at °C using a single spreader and a speed of 20 cm/min.
A completely wet product (clear) was obtained. The residence time in the bath under these conditions was approximately 30 seconds. Using three spreaders, the linear speed can be increased to 120cm/
Clear, well-wet pultrusion moldings could be obtained in minutes. The residence time under these conditions is approximately
It was hot in 10 seconds. Example 7 A number of polymers were used according to the general procedure of Example 1 to produce a pultruded part from a glass roving containing 16,000 filaments. The roving was drawn through the molten polymer over one spreader bar at a speed of 15 cm/min to obtain a product containing in each case about 65% by weight glass. The polymers used, the melt temperatures used, their melt viscosities at viscosities and the properties obtained are detailed in Table 4.

[Table] *= Some decomposition occurs In the case of polyethylene terephthalate,
The effect of void content on physical properties was examined by increasing the draw speed above about 15 cm/min. Table 5 below
Record the properties measured for the 3 mm diameter rod produced. As these show, noid contents of less than about 5% give superior properties.

[Table] Example 8 A sample of polyetherketone reinforced with carbon fibers was passed through a bath of molten polyetherketone through a tape of carbon fibers containing 6000 individual filaments at a temperature of 400°C and 25 cm/min. It was produced by drawing at a speed of . Flexural modulus of 80GM/ ^M2 , breaking stress of 1200MN/ ^m2 and
A product with an interlaminar shear stress of 70 MN/m ² was obtained. Example 9 This example demonstrates how the mechanical properties of the pultrusion vary with fiber volume fraction and resin type. Samples were compared at a fixed volume concentration. The low bending strength of polypropylene-based composites reflects the tendency of the less stiff resin to fracture in compression mode. Polypropylene resin has a modulus of about 1 GN/ ^m2 , while polyethylene terephthalate has a modulus of about 2 GN/ ^m2 . The pultrusion was made according to the general procedure of Example 1 using resin at the preferred viscosity level, about 3 Ns/m ² .

[Table] As this example shows, high modulus resins are clearly superior for applications requiring high compressive strength. Example 10 A sample of 64% glass in PET was pultruded to form a tape 6 mm wide by 1.4 mm thick.
The tape was remelted, wound under tension on a 45 mm diameter former, solidified on the former, and then allowed to cool. After cooling, the former was removed to obtain a tube of filament rolls. Tubes of varying thickness up to 4 mm were formed in this way by winding. Example 11 A 3 mm diameter uniaxially oriented pultruded sample based on PET containing 64% glass by weight was remelted and twisted so that the fibers were in a helical shape. These twisted rods were tested in bending and the stiffness breaking force and total work to failure were measured. The total work of failure is determined as the area under the force-deformation curve to failure, and for convenience,
Here it is expressed as a function of the area under the untwisted control sample.

[Table] At 11°, the stiffness and breaking force are only 10
There is a % reduction while the total work until breakage is 30
% increase to improve the balance of properties. At 23°, both stiffness and strength are reduced by about 60% and work of failure only increases by 60%. This indicates that the optimum twist is around 11°. Thermoplastic pultrusion is more suitable than thermoset pultrusion because it can be easily post-molded and thus offers the advantage of this energy absorption mechanism. Example 12 A 3 mm diameter pultrusion containing 50% by volume glass fibers in PET was melted at 280°C and then braided together. Although this braided product was less stiff than the uniaxially aligned material, it absorbed more energy in impact failure tests. Example 13 Approximately 1.4 mm thick, 6 made from a material containing 50% by volume (64% by weight) glass fibers in PET.
Flat tapes of mm width were woven together in an opentabby weave. Four layers of the fabric were stacked together and compression molded at 280°C into a 3 mm thick sheet. This sheet had the following properties: Flexural modulus (maximum) ^* 15 GN/m ² Impact energy...initial 7 J...breakage 25 J *Slightly lower values are at an angle of 45° to the natural orientation of the fabric would be expected in Example 14 Various pultrusion samples were placed into conventional injection molds and a compatible polymer was molded around them. The moldings had increased stiffness and strength. Thermoplastic pultrusion moldings are particularly suitable for reinforcing molded articles in this manner since they can be made with polymers that are completely compatible with the polymer to be molded around the reinforcement. Example 15 A material containing 65% by weight glass fibers in PET was shredded into 1 cm lengths and 30% by weight in PET.
A conventionally formulated material containing short glass fibers was diluted on a 50/50 basis. This mixture
ASTM bars were produced by injection molding using standard techniques and properties were compared to a conventionally compounded material containing 50% by weight glass fiber in PET.

Table: Examination of the ashed portion of the molded article revealed that the majority of the long fibers were retained throughout the molding operation. This unexpected property is believed to result from the low void content in the shredded pultruded material or from the high degree of wetting of the fibers with the polymer. Example 16 PET containing 60% by weight of glass fibers and
Various pultruded samples containing PEEK containing 60% by weight carbon fiber were cut to 1 cm lengths and molded according to the method described in British Patent Application No. 8101822. In the method of the said British application, the expanded reinforcement material is produced by extrusion through a short length, preferably zero length, die and subsequently compression molded to form a three-dimensional reinforcing material containing 60% by weight of long fibres. Manufacture molded products. Pultruded materials are particularly suited for this application because the high level of wetting obtained effectively protects the fibers and reduces the wear between the fibers that causes fiber breakage. Example 17 According to the procedure of Example 1, PET having a melt viscosity of 3 Ns/m ² at 280°C was used, and the thickness was approximately 1.4 mm ×
Approximately 0.2m/width 6mm cooled sizing die
Tapes were produced that were formed at a linear speed of 1 minute. Not all commercial glass fibers are ideal for pultrusion with thermoplastics. The most important difference lies in the size system used.
Several commercially available grades were compared along with a study of the effect of crystallinity. When manufactured, the pultruments were amorphous, but they
It crystallized easily by heating to 150°C.
In the following table all samples of different glasses are compared with the same weight fraction of glass fibers of 64% by weight.

Table: Crystalline forms that give high stiffness are preferred for many applications, but it is important to maintain high values of interlaminar shear stress (LISS), preferably greater than 20 MN/m ² . Example 18 High performance composite materials are often required to enable use at high temperatures. Using a material containing 64% by weight of the glass E used in Example 17 in PET, the following properties were measured at elevated temperatures for the crystalline pultrusion material.

【table】

Table Example 19 Hot water is an aggressive environment in which composite materials are required to retain their properties. Samples based on 64% by weight of glass fiber E used in Example 17 were pultruded with PET and soaked in a 95°C water bath for varying times. Samples were tested both amorphous and crystalline. Properties deteriorated over time, with interlaminar shear strength (ILSS) being the most sensitive property.

Table: In some other glass systems, the interlaminar shear strength deteriorated to less than 10 MN/m ² after 4 hours of exposure. Example 20 Fatigue resistance is an important factor in the use properties of composite materials. A well-wet pultrusion sample was prepared based on a material containing 64% by weight of the glass fiber E used in Example 17 in PET. A sample was tested in bending to study the stress/strain relationship at 23°.

Table: The sample had a linear elastic limit at 1% strain. The samples were bent at a rate of 1 cycle/2 seconds using a span of 70 mm in 3-point bends. The number of cycles was recorded for significant damage induced (as judged by whitening of the pultrusion).

[Table] The samples were strained at 0.1% strain and the properties of the samples were evaluated after different histories.

Table: Tests were included that evaluated samples with surfaces that were under tension during fatigue history in both compression and tension. No differences were observed between these two modes. The properties of the pultrusion were not affected by this fatigue history. Example 21 A sample of tape approximately 1.4 mm thick x 6 mm wide was
Manufactured based on the material containing glass fibers used in Example 17 in PET. The glass content was varied and in all cases the pultrusion was transparent.

Table: Example 22 High linear velocities are highly desirable for economical production.
A pultrusion containing 69% by weight of the glass fiber D used in Example 17 in PET was formed by drawing the pultrusion through a melt bath containing five spreader bars. Well-wet pultruments were obtained at the following speeds and their properties were measured in bending.

EXAMPLE 23 A pultrusion was made from the material containing the glass fibers E used in Example 17 in PET using a single spreader at 280°C. Changed the viscosity of the resin. Using a very low viscosity resin, some resin was squeezed out of the pultrusion during the molding step which compressed the pultrusion to a width of 6 mm by a thickness of 1.4 mm. The linear velocity was fixed at 0.2 m/min. The pultruments were flexurally tested in both amorphous and crystalline form. The crystal form is
The samples were obtained by briefly heating them to 150°C.

[Table] *Poor Wetting Samples with very low viscosity gave useful properties in the amorphous state, but upon crystallization the properties deteriorated. At high viscosities, the glass wetted poorly (thus giving a low resin concentration). Example 24 The glass fiber E tape used in Example 17 was pultruded onto a single spreader (in PET with a melt viscosity of 3 Ns/m ² at 280°C) to give a well-wetted, 6 mm Tapes were obtained of different widths but different thicknesses by incorporating different amounts of glass. The sample tested was amorphous.

[Table] Example 25 Glass fibers of different diameters were pultruded together with PET. The sample tested amorphous had the following properties:

[Table] Example 26 Using polyethersulfone with a melt viscosity of 8 Ns/m ² at 350°C, the glass fiber E used in Example 17 was spread at a rate of 0.2 m/min using a single spreader system. Impregnated at linear speed. The following properties were obtained.

Table: Example 27 PEEK having a melt viscosity of 30 Ns/m ² at 380° C. was used to impregnate carbon fibers at 0.2 m/min in a single spreader pultrusion machine. A 3 mm diameter rod containing 60% by weight carbon fiber was formed. Example 28 A blend was made from ordinary glass-filled PET (short fiber compounded material made by extrusion compounding with PET with an intrinsic viscosity of 0.75) and chopped into 10 mm pultrudates (as per Example 3). manufactured).
Injection mold these blends to 1.5 thickness x width
Filling from a rectangular side gate of 10mm diameter
A disk of 114 mm and 3 mm thick was formed. These samples were exposed to impact in an instrumented drop weight impact test and the failure energy was recorded.

Table: All samples were filled into molds with similar ease. This is because the polymer used to make the pultrusion had a lower molecular weight than the polymer used to make the short fiber formulation, and this lower molecular weight polymer offset the increased resistance to flow due to the long fibers. It is from. The results clearly demonstrate the increased failure energy of long fiber filled materials despite the low molecular weight of the polymer, which is normally expected to contribute to brittleness.
In particular, tests No. 2 and No. 4 and the same total weight percentage of fibers should be compared. Additionally, short fiber moldings can tear on impact, throwing off sharp plastic fragments, but when more than half the weight fraction is long fibers, the moldings can safely break apart and release all sharp plastic fragments. It was observed that the broken pieces were attached to the main part and left behind. Ashing of the moldings after testing revealed that many of the long glass fibers retained most of their original length. of the original length of fibers in the molding.
Significantly more than 50% by weight was of length greater than 3 mm. The samples were also evaluated for flexural modulus, anisotropy ratio, Izod impact strength, and intrinsic viscosity (IV) of the polymer in the mold. The values in the table below indicate reduced anisotropy and superior notched impact strength for short fiber products.

Table: Example 29 Continuous carbon fibers, each containing 6000 individual filaments (supplied by Cortland,
14 tapes of carbon fiber (labeled as XAS),
It was pulled over a series of stationary guide bars at a speed of 25 cm/min to form a band approximately 50 mm wide with a force of approximately 100 pounds (45.4 Kg). Once the fibers were guided into side-by-side relationship, they were drawn over a single fixed heated cylindrical bar of 12.5 mm diameter. The temperature of the bar was maintained at approximately 380°C. A polyetheretherketone powder having a melt viscosity of 20 Ns/m ² at this temperature was fed into a nip formed between the carbon fiber band and the fixed roller. The powder rapidly melted to form a pool of melt in the nip, which impregnated the band of fibers passing over the rollers. This structure was passed over and under five additional heated bars without adding any further polymer. A carbon fiber reinforced sheet containing 58% carbon fiber by volume and having a thickness of 0.125 mm was produced. This product was found to have the following properties. Flexural modulus 130 GN/m ² Bending strength 1400 MN/m ² -layer shear strength 90 MN/m ² Example 30 Following the procedure of Example 29, 3 Ns/m at 360°C
Polyethersulfone with a melt viscosity of m ² was used to produce a reinforced product containing 40% by volume of carbon fibers. The temperature of the roller is approximately 360
It was maintained at ℃. This product had a flexural modulus of 80 GN/m ² and a flexural strength of 700 MN/m ² . Example 31 Following the procedure of Example 29, a commercially available polyethersulfone PES ^200P (Imperial, Chemical,
available from Industries PLS). The roller temperature is maintained at approximately 360℃, and 44
A product containing % carbon fiber by volume was produced. The product had the following properties. Flexural modulus 60 GN/m ² Flexural strength 500 MN/m ² Interlaminar shear strength 25 MN/m ² Example 32 Following the general procedure of Example 29, 14 tapes of continuous carbon fiber (“Courtaulds” XAS, 6K tow) and 370 It was prepared using polyetheretherketone with a melt viscosity of 30 Ns/m ² at °C. In the apparatus, five cylindrical bars, each 12.5 mm in diameter, were heated to 380°C. 14 tape was pulled under tension to form a 50 mm wide band, which was passed through an adjustable nip formed by the first two bars with their longitudinal axes horizontal. This band was subsequently passed under and over three additional heated bars whose longitudinal axes were also horizontal. The first two bars were used to form a nip, which allowed polymer to be delivered to both sides of the band. To prevent polymer spillage, two retaining metal sheets were placed in contact with and along the length of the two heated bars to form a feed trough. Polymer powder was fed on both sides of the band passing through the first two heated bars. The powder was rapidly melted to form a pool of melt in two nips formed on either side of the band and between each heating bar. When the gap between the first two bars is adjusted and the pulling speed is 0.5 m/min, the carbon fibers are coated with the polymer and the resulting impregnated tape contains approximately 60% carbon fiber by weight. and 40% by weight of polymer. It has been found that adjustment of fiber content can be achieved in several ways. 1 Change the nip gap. 2. Change the pre-tension. 3. Change the number of filaments supplied to the nip. 4 change the powder feed rate; 5 change the temperature of the bar in the nip (for the resin used in this example, the preferred temperature range is below 400°C for decomposition and 360°C for initiation of crystallization). 6. Change the pulling speed. The tape thus formed appeared to wet well and was approximately 0.1 mm thick. Example 33 The tape described in Example 32 was cut to a length of 150 mm and stacked into a matte die compression molding tool. This device is placed in a standard laboratory press.
Heated to 380℃, and the molding was heated to 2-5×10 ⁶ N/
It was compressed to receive a pressure of m ² . This molded product
Hold at that pressure for 10 minutes (it took half that time for the mold and sample to reach equilibrium temperature),
Then heated to 150℃ under pressure before removal from the press.
It was cooled to The cooling stage took approximately 20 minutes. The mold was cooled to ambient temperature and then the mold was removed. Thickness 0.5mm (4 ply) to 4mm (38 ply)
Moldings having a range of . During the molding operation, a small amount of polymer was squeezed out of the mold as flash, resulting in a molded product containing 62% by weight carbon fiber compared to 60% by weight in the original tape. The moldings were then cut with a diamond wafer saw to form specimens suitable for mechanical testing by bending techniques. The following results were obtained.

EXAMPLE 34 Using the same equipment as in Example 32, several poorly wetting tapes were made by using less feed in some areas of the tape and more feed in other areas. The overall fiber content of the tape was the same as Example 4, but many free fibers appeared on the surface of the tape and other areas were resin rich. The tapes were stacked and molded as described in Example 33, taking care to place the less wetted areas of one tape adjacent to the resin-rich areas of the next tape. Visual inspection of the moldings revealed that substantially no wet areas remained and the released fibers could be easily pulled from the surface.
The mechanical properties of these moldings are inferior to those observed in Example 33, and in particular the interlaminar shear strength is variable and has a low value of 10 MN/ ^m2 (compared to 81 for the well-wet sample). ) were common. As this example shows, wetting of the fibers occurs primarily during the impregnation stage and not during the secondary shaping stage. However, it is believed that some degree of wetting may be achieved with higher pressures and longer residence times. Example 35 The tape formed in Example 29 was torn to approximately
Tapes with a width of 15 mm were formed and these tapes were woven in tabby weave (described in the Encyclopedia Bricanica section on textiles) to form sheets approximately 150 mm square. Example 36 The single woven sheet described in Example 35 was compression molded as described in Example 33, except that the molding was simply carried out between the aluminum sheets without constraining the sidewalls. The extrusion was a flat sheet with a thickness of 0.2 mm. In further experiments, five woven sheets as described in Example 7 were layered together, with each layer oriented at ±45° relative to the layers above and below. This stack was compression molded to form a 1 mm thick sheet without constraining the side walls.
A 135 mm diameter disc was cut from this sheet and its stiffness and strength was determined using the technique described by CJ Hooley and S Turner (Mechanical Testing of Plastics,
Institute of Mechanical Engineers, June/
July 1979, Automotive Engineer) using a disk bending test and an automated falling weight impact test. The bending stiffness of the plate is a maximum of 50GN/ ^m2 and
It had a minimum value of 36GN/ ^m2 . The impact resistance of the sheet was as follows: Initial energy 1.7 (0.3) J Failure energy 6.6 (1.1) J (Standard deviations are in brackets) Parallel sides cut along the line of maximum stiffness A sample with
I got the following results. Bending modulus 51GN/ ^m2 Bending strength 700GN/ ^m2 Example 37 Example of a disk with a diameter of 135 mm and a thickness of 1 mm.
36 and subjected to 19 impacts of 3J evenly distributed over the surface of the disk. These impacts caused some delamination, but the damaged moldings remained cohesive. The damaged disc was then remolded and then described in Example 36 with the following results.

[Table] There is no significant difference in the results. As this example shows, the properties are fully regenerated after partial damage. Example 38 A damaged disk made as in Example 37 failed in five impacts using an instrumented drop weight impact test. The damage was localized in an area not much larger than the cross section of the impactor, and all fractured parts remained attached to the body of the molding. The broken molding was then remoulded and an impact test was carried out, taking care to direct the new impact to the previously broken spot, with the following results. Initial energy 1.8 (0.4) J Failure energy 4.6 (0.8) J (Standard deviations are in brackets) By comparison with the results of Examples 33 and 34, this shows that even in the worst possible case,
It shows that almost 70% of the original strength can be recorded. Example 39 A 135 mm diameter, approximately 1 mm thick disk made according to Example 36 was heated to 380°C and then placed in one half of a cold hemispherical female mold 200 mm in diameter.
Press the male half of this mold down by hand to 100mm.
formed a hemispherical section with a radius of curvature of . Sections up to approximately 100 mm in diameter (subtending a solid angle of approximately 60° from the center of the sphere forming the section) conform well to the double curvature, although some bending occurred outside this area. Example 40 A sheet woven from a tape having a width of 5 mm using five pieces of satin weave (as described in the section on textiles in the Encyclopedia Britannica) was produced. In the dry state, this fabric had a very good structure with a double curved surface and pores formed in the fabric. 5
Producing a quasi-isotropic sheet of layers and Example 36
It was molded as described in . This 1 mm thick sheet was then heated to 380°C and molded onto a variety of cold surfaces including: 1 right angle, 2 cylindrical surface with a radius of curvature of 25 mm, 3 a radius of curvature of 15 mm. Spherical surface with. In cases 1 and 2, excellent agreement was obtained. For double curvature, stretch from the center of the sphere
Excellent matches were obtained up to a solid angle of 60° (this is similar to the experiment of Example 39, but at a tight radius of curvature with respect to the sheet thickness). Largest structures require only gentle double curvatures, while tighter curvatures require narrow weaves, especially in satin weaves, which are preferred over wide tabby weaves in accordance with the general experience of the textile industry. Example 41 A piece of 40 mm square material was woven from a tape 2 mm wide and 0.1 mm thick (tabby weave). The moldability of a sheet of this material was compared to that of the wide tape fabric described in Example 35. The narrow tape could easily adapt to shape changes. Molded sheets formed from these two types of fabric appeared superficially similar in properties. Because of the use of common textile techniques, narrow tapes are likely to be used in practice. Example 42 An attempt was made to stack the tapes formed in Example 32 to form a multilayer composite with each layer having a different orientation. Because the tape is not "sticky" at room temperature when freshly formed, the layers had a tendency to move with respect to each other during the placement and molding operations, so the fibers were oriented in the designed configuration in the final molding. Nakatsuta. This problem can be solved by locally gluing the layers together with a soldering iron.
partially overcome. When formed like this,
The sheet had to be shaped with a constrained sidewall to prevent the fibers from flowing laterally and disrupting the designed orientation pattern. In contrast, woven sheets are convenient and easy to handle, and the interlocking structure itself prevents lateral movement of the fibers.
Molding was possible without constraining the side walls. The ability to form preferred sheets without constraining the sidewalls is particularly advantageous when considering continuous sheet fabrication by methods such as double band pressing. Example 43 Woven sheets according to Example 35 were stacked and molded to form sheets of different thickness, with each layer lying at ±45° to the layer above and below. The impact behavior of these sheets was determined by an instrumented falling weight impact test.

[Table] Example 44 Following the procedure of Example 44, polyether sulfone “Victrex” 200P and carbon fiber (Courtaulds
The tape was manufactured from (XAS, N. size). This polymer has 800Ns/m ² at 350°C and 400°C.
It had a melt viscosity of 100Ns/ ^m2 . Spreader approx.
The temperature was controlled at 370-380°C, and the drawing speed was 0.2 m/min. Due to the high viscosity of this resin, the tape did not wet as well as that described in Example 32. By slightly increasing the resin content,
The final tape contained 50% carbon fiber and 50% resin by weight. Samples were formed as described in Example 33 to form uniaxially oriented sheets with the following properties: Flexural modulus 60 GN/ ^m2 Flexural strength 500 MN/ ^m2 Transverse bending strength 20 MN / ^m Interlayer Shear Strength 26 MN/m ^2The tape was then woven, layered and formed according to Examples 35 and 36 to have the following properties:
A sheet with a thickness of approximately 1 mm was formed: Bending stiffness (maximum) 24 GN/ ^m2 Bending stiffness (minimal) 21 GN/ ^m2 Impact energy (initial) 2.9 (0.3) J Impact energy (damage) 7.1 (0.3) J ( (Standard deviations are in brackets) The fractured sheet was remolded and retested, taking care to impact the sample at the same spot as the original impact damage. The bending stiffness of the reshaped sheet was 10% lower than that of the original sheet, but the impact resistance was lower than that of the original sheet.
decreased to 60%. Example 45 Polyethersulfone having a melt viscosity of 8 Ns/m ² at 350° C. was used to impregnate a carbon fiber tape. The carbon fibers were previously sized with 5% by weight polyether sulfone by a solution sizing method. This sample makes it 350
0.2m/top of four spreaders heated to ℃
Impregnated by drawing at a speed of 1 minute. The final composite material contained 47% carbon fiber by weight. A sample was molded and tested according to Example 30,
The following results were obtained: Flexural modulus 85 GN/m ² Flexural strength 680 MN/ ^m Bilaminar shear strength 50 MN/m ² Although this sample was made from a lower molecular weight polymer than that used in Example 44, It is recognized that the properties of the composite material are excellent. Example 46 Glass rovings were made of polyethylene terephthalate (melt viscosity of 3 Ns/ ^m2 at 270°C).
Impregnation was carried out following the procedure described in 32, but using a bar at 280-300 °C. It was possible to satisfactorily incorporate glass fiber up to 80% by weight and provide excellent wetting. At 60% glass by weight, a line speed of 5 m/min was easily achieved for a 0.1 mm thick tape. Example 47 A glass roving was impregnated with polypropylene having a melt viscosity of 10 Ms/m ² at 270°C using the same equipment as in Example 32, but keeping the bar at 270°C. At 50% by weight glass fibers, a very well wetted 0.1 mm thick tape was obtained, which was particularly useful for overwrapping tubes and other parts made from polypropylene. Example 48 A thermotropic polyester containing residues of hydroxynaphthoic acid, terephthalic acid and hydroquinone and having a melt viscosity of 7 Ns/m ² at 320°C,
Impregnated with carbon fiber (“Celion” 6K and 3K tow). The equipment was the same as described in Example 32, except that the bar was maintained at 320°C. The 0.1 mm thick tape containing 62% by weight carbon fiber had excellent appearance. Example 49 Example 32, including certain materials containing excess resin
The various pieces of scrap material prepared from 38-38 were broken up and fed into a conventional screw extruder and compounded to form granules. The granules contained carbon fibers up to 0.25 mm thick. These particles,
Injection molding was performed according to conventional molding techniques and under standard operating conditions for filled PEEK. The moldings have the following properties, which are compared to those of the best available commercial grade carbon fiber filled PEEK produced by conventional compounding operations:

[Table] Surface quality Excellent Excellent
As is clear from this example, the product of the present invention can be converted into a product for conventional processing methods, which is much better than that which can be obtained by limited technology. Excellent in terms of Additionally, scrap from various long fiber operations such as sheet manufacturing, lamination, filament winding, etc. can be recycled into high performance materials. Renewability properties have great economic implications when working with expensive raw materials such as carbon fiber. Example 50 The optimum tension in the roving when working according to the method of Example 29 was determined by measuring the tension in individual rovings containing 6000 filaments before impregnation and during the tensioning stage. (14 rovings were used in Example 29 and the working tension would actually be 14 times the value given below). The values below were determined to be the minimum working tension (Case 1) and maximum working tension (Case 2) for the particular roving, polymer type and equipment used. Case 1
When using tension values less than the value of , fiber misalignment and tearing were present in the tapes produced. With tension values larger than those of case 2, fiber abrasion was observed and released fibers accumulated on the band. For different sets of conditions (roving, polymer type, etc.) the values obtained are different but can be easily optimized to obtain products of excellent quality. Tension before impregnation Tensile tension Case 1 0.14Kg 2.4Kg Case 2 0.37Kg 3.8Kg

Claims (1)

[Claims] 1. A fiber-reinforced pellet having a length of 2 to 100 mm and comprising a low molecular weight thermoplastic polymer and at least 30% by volume of parallel-aligned reinforcing filaments, and having a molecular weight higher than that of the polymer of the fiber-reinforced pellet. and a thermoplastic polymer which may be the same or different from the polymer of the reinforcing pellets.