DE2159358A1 - Fiber reinforced resin composites and processes for their manufacture - Google Patents

Description

Fiber-reinforced resin composites and processes for their manufacture

The present invention relates to the manufacture of reinforced Compositions that heat up under heat and pressure Resistant fiber-resin composites of high strength processed can be. In particular, this invention relates to a continuous and solvent-free process, to impregnate high-performance, reinforcing strands consisting of many single threads with resins and the pre-impregnated compositions produced thereby.

It is e.g. from the French patent i 555 564 and the US Patent 3,179,635 known that fibrous materials, such as strands consisting of a plurality of single threads, spinning

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threads or cables made of glass threads or those made into fabrics Threads can be impregnated with thermoplastic or thermosetting, natural or synthetic resins and that the resulting prepreg compositions under the action of heat and pressure in made of pastes and Resin composites of remarkable strength and strength Heat resistance can be processed (in the field of reinforced plastics one understands by the designation "Preimpregnated material" means the reinforcing material that is combined with the full amount of the resin prior to making the composition forms). When the solidification of such pre-impregnated Materials is performed within a limited space, a molded part can be made that can be used for any specific purpose. On the other hand, when glass fabric is impregnated, layered, heated and pressed the resin hardens due to the action of heat and connects the layers of the fabric to form a laminate. if the pre-impregnated material is a strand or a single thread which is continuously wound in a predetermined manner on a suitable mandrel and then melted and hardened a composite in the form of a sleeve is obtained. Such a technique is known as filament winding.

In general, heretofore in the preparation of such compositions it has been useful to convert them into composites the resin, e.g., a thermoplastic such as an aromatic Polycarbonate, or a thermosetting resin such as a polyimide prepolymer, e.g., a bis-maleimide, an N-phenyl maleimide Pyromellithimide and the like either dissolved or dispersed in a solvent or melted and the reinforcing Fibers, e.g. carbon cables, graphite cables or fiberglass strands, were drawn through a resin bath. Glass fabric is quite compact and therefore no significant problems have been encountered with it uniform dispersion of such a reinforcing material in the resin.

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However, fibrous reinforcing materials show a specific one Difficulty because they have a very high surface area to weight ratio. They are very voluminous. Consequently It is extremely difficult for the viscous, molten, solvent-free resin to penetrate to the inner filaments and to create an even distribution. An undesirable result of using such solvent-free, molten resins in fibrous materials consists in that it is usually impossible to find a suitable lower limit of the Ratio of resin to reinforcement material in the product. Such products usually contain too much Resin. .

On the other hand, it has been suggested, and indeed the usual one Practice, bulky, fibrous, reinforcing materials impregnate with solutions or dispersions of the resin in a solvent and then evaporate the solvent. While this method creates an even resin coating on the fibers, it has been found to be mostly it is impossible to have a coating encapsulating every single thread in the composition that contains essentially no solvent »Because of the presence of the incorporated * · sealed solvent must be the impregnated compositions be molded in long, multi-stage cycles at different temperatures, with the times of the individual cycles can be measured in hours. Even with such long cycles, complete removal of the trapped is Solvent not possible during molding or from a cured composite, as there is often a decrease in Stiffness is observed when a composite is made from a Solvent system has been impregnated is heated to an elevated temperature. ,

In addition to these molding difficulties and the less than optimal thermal properties, the Solvent impregnation technique, considerable capital run-off

Twists and labor costs, as solution center! Elimination and Drying towers necessary, as well as facilities for the Solvent reclamation is required and, ultimately, solvent losses add cost.

It was found in the invention, however, that by a new fluidized bed (fluidized bed) powder impregnation of the fibrous Reinforcement materials and high-frequency vibration treatment of the impregnated fiber materials are excellent Compositions for the production of high-performance Composites can be created.

Since the fiction, contemporary method works without a solvent, the usual, low cost and short-term transmission cycles are used, such as printing forms.

In addition, for a given resin system, the original strength at an elevated temperature for composites, according to the fiction, solvent-free Impregnation methods were produced, larger than those of composites made with the known solvent 1 impregnation method were manufactured.

Because of the solvent-free operation, the process is easily usable for continuous operation and the resin content can can easily be restricted to an advantageous proportion and, moreover, because of the need for recovery and the drying towers and because of the non-occurrence of solvent losses, many disadvantages of the known processes avoided.

Reference is made to the drawing in which the Invention is shown for example. Show in detail:

1 shows an overview of the method according to the invention, including some optional but preferred embodiments of the method,
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Pig. 2 is a somewhat schematic side view in section of a apparatus suitable for carrying out the process according to the invention,.

FIG. 3 shows, similar to FIG. 2, another apparatus for implementation of the η method according to the invention,

Figure 4 is a somewhat idealized, fragmentary cross-section a pre-impregnated composition according to the invention, wherein the threads of the strands each with a continuous layer of solvent-free resin are surrounded

Figure 5 is a somewhat idealized, fragmentary cross-section a pre-impregnated composition according to the invention, in which the threads of the strands are surrounded by a layer of solvent-free resin particles and

Fig. 6 is a somewhat schematic side view of a device in Cut with which a continuous winding of the thread according to the invention is possible. Such a device can for example, together with the apparatus shown in Figs be used.

According to the present invention there is a method of making an alliance made of fibers and resin off it created in which the essential steps are continuous Passing at least one of many threads through Strands comprise pulverized or granulated resin through a fluidized bed, the strand or strands with the Resin are impregnated and then the impregnated strand or strands are passed into a zone with high-frequency vibration, to evenly distribute the powdered resin on each of the individual threads and then the impregnated strand or strands to pull out of the zone.

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Such a process is shown schematically in Pig »I, wherein the essential steps with 1, '4, 5 and 6 are designated.

In the present application, the term "from a Variety of threads of existing strand "include the treated, reinforcing material, the glass, quartz, carbon, graphite or any other filamentary filler suitable for making high performance composites. The filler should have continuous lengths, i.e. at least 1 m (several feet) long and each length may contain any number of individual threads, e.g., monofilaments or groups of such threads, be they twisted or untwisted. Such longitudinal pieces can be in the form of bundles, filaments or strands, ropes, cables, etc. are present, but for the sake of simplicity and without limitation they are taken as strands designated. The procedure is on a single or any one A number of strands are applicable and the strands can comprise a mixture of threads of different types. How to describe will be, a very advantageous process involves the impregnation of strands of glass and graphite, with a Mixed composite with unexpectedly high strength is obtained.

The powdered resin can be thermoplastic or thermosetting be, with the latter type being preferred in order to obtain the best ther * to maintain mixed resistance. It should be in such a State of aggregation which is suitable for an extended To form fluidized bed when the powder is mixed with a gas and vibrated. Any inert gas can be used e.g. air, nitrogen, oxygen, argon and the like. Selected by using particles or granules Particle size distribution makes it possible to adjust to any desired degree of fluidization and resin uptake. When, as usual, the particle size is selected to be all through a .80 Maechen sieve according to the US standard (177 to 250 microns), a resin content in the range of

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20 to 60 wt. JS can be easily obtained depending only on the type of specific paser and the speed with which the one or more strands passed through the fluidized bed will.

Any of the known base resins can be used for the fiction, contemporary method, provided that this forms a composite with the fibrous reinforcement, which has improved mechanical properties. Examples of the generally usable resins are nylon, polystyrene, styrene-acrylonitrile, acrylonitrile-butadiene-styrene, polycarbonate, polypropylene, linear polyethylene, acetal, polyurethane, polysulfone, polyphenylene oxide, polyvinyl chloride and the like. Particularly useful are the thermosetting phenolic resins, melamine-formaldehyde condensates, the epoxy compositions, the polyester resin compositions and the like. However, the polyimides and the modified polyimide prepolymers, of which N, N ¹ -bismaleimides, N, N'-bismaleimides modified with polyfunctional amines, N-phenylmaleimides, pyromellithimides and the like may be mentioned, are of very particular utility. A special mention is made of the reaction products of an NjN'-bisimide of an unsaturated dicarboxy acid of the general formula

N -R N

"O

where R is a divalent group with a carbon-carbon double bond and R is a divalent group with at least two carbon atoms, for example NjN'-bismaleimidoCM, !! ¹ -dipheny! Methane) and a diamine of the general formula

2159359

wherein R is a divalent group of up to 30 carbon atoms is, for example 4,4'-diaminodiphenylmethane. Such resins are in that described above French patent ".

With reference to FIG. 1, the invention is explained in more detail below described. The strand or strands that are wound onto a spool or similar loading device (1) are if desired, a heat cleaning and / or fluffing siation (2) fed. Then the threads of the strand are possibly ... by passing over devices (3), such as rollers, on spread out. Next is the strand or strands through one powdered or granulated resin passed in a fluidized bed and the strand or strands are impregnated (4). Finally, the impregnated strand or strands are passed through a High frequency vibration zone (5) to evenly distribute the powdered resin around the strand, especially on each of the single threads. Finally, the resin powder impregnated strands are ready for use as such, e.g. Heating coils, wound or for use in the following optional steps, such as cutting (6a) and shaping (7). On the other hand, the strands impregnated with resin powder can also either be cut and heated (to melt the resin and encapsulate the fibers) or heated and cut (6b). The next step can also be shaping (?).

With reference to the individual steps which depend on the type of fiber to be fed and that to be used in the fluidized bed Depending on the resin, note the following:

Step (1), the feeding of the strand, is carried out in any conventional manner, e.g. by inserting a drum spool (drum feed unwind spool), which is combined with a hysteresis brake.

Stage (2), the optional heat cleaning and / or loosening by means of a gas jet, is used to loosen the tightly knitted bundles and to prepare the surface for the

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Impregnation with the powder used. A jet of air can be used alone, but it is preferable to use a high temperature zone in a free flowing air system. The heat can be supplied in any conventional way, for example by means of a tube furnace or by directing the beam over a hot insert (shoe). It is desirable to heat the fibers to at least about 350 ° C, but not above 900 ° C. The temperature to be used depends on the paser to be impregnated. Preferably, the heating is carried out at temperatures above 500 ^0C. For continuous graphite cables, 650 to 750 ° G is most common. With continuous carbon-glass cables and with glass, 520 to 550 ^° C. appear most suitable. However, graphite and glass can conveniently be treated simultaneously at 550ºC. For many fibers, the heat pretreatment seems to be an essential factor for a low surface charge on the fibers in the eddy current bed.

Stage (3) is the optional separation to be carried out of the fibrous strand before entering the eddy current bed. An air jet in stage (2) supports this stage; however, some additional devices are preferably used, like a roll or rows of rolls to flatten the fiber bundle and widen it into wider strips or similar shapes. This stage, although to be carried out only optionally, is preferred because the thicker strands are separated into. many thinner groups of individual threads provide better dispersion of the resin.

Stage (4) is a continuous impregnation of the or the Strands in a fluidized bed of powdered or granulated resin. Such a bed can for example be contained in a chamber which is supplied with dry air and which comprises a vibrating device such as a ventilated vibrating unit. According to one embodiment, air is passed through a porous, plate-like gas distributor in finely ground powdered Resin, which expands the powder bed and whirled up. The vast and spreading

Strands are made by rolling in the dense phase of the particles guided. The activity of the bed serves to further blow the threads apart during the coating with a uniform Powder layer. The particle size of the resin can be in vary fairly wide, but particles are preferred of about 80 microns, the low proportions are used contain larger particles such as 200 microns to facilitate fluidization. Resin absorption From 15 to 60% by weight are preferred at this stage.

In the following step (5) the powder-impregnated strands exposed to high frequency vibration. This step is from Significance to achieve uniform resin dispersion * penetration and overall control. In addition, it seems as if a static charge is being created that will keep the plague the resin particles supported on the threads. One type of execution for this stage consists in the vertical movement of the strands through a settling space above the dense phase of the powder particles, which exposes the strand to high frequency vibration. The finer resin particles adhere to the fiber, obviously only a small surface charge is present, the appears to enlarge as the strand vibrates. The vibration removes the excess, loosely held Resin particles. '

In the next stage (6) the resin-impregnated strand is opened taken in a suitable manner, such as by a motorized sink. The speed at which the strands are increased depends on the geometry of the fluidized bed chamber and the desired residence time away. Merely as an example it should be given that with a room filled with the bed of about 17 * 8 cm (7 inches) Diameter and about 28 cm (11 inches) high and an average powder depth of about 3.2 cm (1 l / M inch) unflurried and about 5.1 cm (2 inches) of fluidized powder, the speed the fiber uptake can be about 1.5 m / min. Higher speeds are possible with larger fluidized bed chambers, in order to comply with the necessary residence time. If desired, the powder-impregnated strands can be used

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be cut to any suitable length for shaping (6a), for example to about 3.2 now to about 51 mm. Pieces from about 1.27 cm to about 2.5 * 1 cm are particularly suitable. On the other hand, the powder-impregnated strands may possibly cut _r and heated, or heated, such as by passing it continuously through a furnace, and then cuts (6b). The heating is carried out to create a molten, uniform, solution-free layer of resin around each individual thread of the strand (thermosetting resins will also polymerize to a large extent in the process). For polyimide resins, such heating can be carried out at a temperature of about 80 to about 350 ^° C. for a time of about 6 hours to about 30 seconds. The heating is preferably carried out for 5 to 30 minutes at a temperature of about 150 to 180 ° C., depending on the degree of flow.

In step (7) the preimpregnated compositions are formed into the final shape of the reinforced composites. this will carried out according to known methods. For polyimides e.g.

Mold pressures from about 35 to about 42O kg / cm and preferably from

2
about 105 to about 280 kg / cm are applied. The mold temperatures are generally in the range of about 80 to about 3 ¹ IO ⁰ C and preferably of 'about 150 to about 230 C. The molding times to' at least 'from Seih sufficient for a complete curing of the resin and will depend on the temperature. The overall cycle can generally vary between 90 seconds and about 2k hours (if one includes, for example, a 24-hour post-curing).

In addition to the method of manufacture, the present invention also provides a pre-impregnated composition comprising Heat and, depending on your choice, also pressure to make composites from with

.11. J ₁ -

fibrous materials reinforced resin are processed can. The composition comprises at least one of trMen Threads of existing strand or strands that form an im have substantially continuous layer which forms a sheath for each individual thread, the layer being a

Comprises resin formed in situ on each of the strands in the strand or strands.

Such a pre-impregnated composition is shown in somewhat idealized form in Fig. 4 in partial cross-section. It can be seen from this figure that the monofilament 8 _{S is} usually glass, carbon, graphite, quartz or a similar fibrous reinforcement surrounded by or encapsulated by a continuous, solvent-free layer of the resin 10. The resin can be either thermoplastic or thermosetting, the latter of which is preferred and is typically a polyimide of the type described above. The pre-impregnated composition shown in FIG. 4 can also consist of strands in which the individual threads are a mixture of materials, for example a mixture of individual graphite and glass threads.

The present invention also provides a pre-impregnated composition which can be converted under heat and possibly under pressure into a composite composed of fibrous reinforcing material and resin or, if the resin is thermosetting, under the action of heat into the pre-impregnated composition described above (Fig. ¹ O can be converted, the composition comprising at least one strand consisting of a plurality of monofilaments, each of the monofilaments in the strand or strands having around it a layer of particles composed of an in-situ meltable resin around a substantially continuous one to form a solvent-free layer on each of the individual threads while these are combined in the strand or strands.

Such a pre-impregnated composition is something in FIG shown idealized in partial cross-section. In this figure, the individual threads 12 can be recognized, which are usually made of GlaSj Carbon, graphite, quartz or similar fibrous reinforcing material consist,. · which are provided with a uniform layer 1 ^ 4 of powdered resin, the resin either thermoplastic or thermosetting, the latter is preferred

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and typically a polyimide of the type illustrated above. The objects and objects of the present invention are achieved when, as shown, the strand bundle is divided into individual filaments which are encapsulated with a minimal volume of resin * such a coating prevents resinous Sereiche and poor transfer of load between the elements "the prepreg 'composition of Fig. $ may also consist of strands ,, in which the individual filaments comprise a mixture of materials, eg," a mixture of individual graphite and Glass threads i

The multitude of threads is no matter what the design preferably continuously *

Although the compositions according to the invention on different Ways can be obtained, for example, by knocking down the shroud Resin on the fibers, by applying powdered Resin on the fibers and then melting, by knocking down from a solvent and subsequent complete elimination of the solvent and the like coating with the new, continuous, solvent-free Fluid bed process described above is preferred *

The contents can vary considerably * but they are aeolian preferably in the range from 15 to i® & ew. # * forift times, temperatures and pressures correspond to those in this field usual values, and those given above are preferred Conditions met. "

A typical ruckform cycle is shown below for illustration with a carbon or

without preheating the compound

■ <1) The mold is filled cold and then just S ¹ O a lot of yellowing, ⁵ um-die l? Orifi ä ^ ä snüeSen Ckiss presaureH heating the mold and isusaWnenisefeizsung to ISO ^ »i ^ i $ 5 rock 36'5

- "ait -

(3) Apply a pressure, e.g., up to about 210 kg / cm

(3000 psi),

(4) further increase the temperature to about 225 ⁰ C (HkO ⁰ F) and

(5) Leave at about 225 ° C for about 1 minute per mm of thickness of the part to achieve complete hardening.

If the pre-impregnated material is intended for a continuous, in-line pad winding should be used to To make composite material, one will proceed as follows to have:

After the fluidized bed chamber> as shown for example in Figures 2 or 3, an apparatus such as in Fig. 6 shown, set up »

The method comprises continuously passing at least one strand consisting of a plurality of filaments through a fluidized bed of pulverized resin to impregnate the strand or strands with the resin, passing the impregnated strand or strands through a zone of high frequency vibration around the distributing powdered resin evenly on each individual thread, winding the impregnated individual threads in a predetermined pattern on a device such as a mandrel to create a workpiece, e.g. an existing on the windings sleeve ^ and

Heat the winding of the workpiece to melt the resin and to form the Verto ^ undsfcoff.

Like öfcen ei-wrltent ^ koimera thermoplastic or high-strength Harae can be used, the latter being preferred and are particularly suitable »There is a preferred amen the pre-coated materials before winding «R & it & eiu © as procedure is based on the following examples in the

example 1

An apparatus such as that shown schematically in FIG. 2 was used is shown.

A strand of graphite (or cable) 20 on a spool 16 containing several 10,000 filaments about 7.5 microns (0.3 mil) in diameter and about 0 »3 g (0.01 oz) weight per 30 cm covered with a hysteresis brake 18 is provided, was continuously passed through an air jet 22 in which the tightly linked bundle of threads was loosened. A series of concave rollers 24 helped guide the bundle from one another to form a wider belt which was continuously fed to a fluidized bed 32 in a chamber 26 which was provided with a dust collector 38. The chamber, which was approximately 18 cm in diameter and 28 cm in height had a space 27 to which dry air was fed and contained an air-driven vibration unit 40. The dry air passed a porous plate 28 acting as a gas distributor and passed through a finely divided, thermosetting polyimide resin powder (condensation product of N, N ¹ -bismaleimido (4, 4 ^l -diphenylmethane) and methylenedianiline, which was produced according to French patent 1 555 564) and whirled up the powder bed 32, as a result of which it expanded from a thickness of about 32 mm to a thickness of about 51 mm.

The particle size distribution was as follows:

US standard Micron- ^ Portion Sieve no. area 71.4 80 177-250 18.3 140 105-177 0.5 170 88-105 9.3 270 53-88 0.4 finer <44

The loosened and disconnected strand was carried out by means of further rollers 30 passed through the dense particle phase. the

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Activity of bed 32 served to further blow apart of fibers, while those with an even layer of powdered polyimide resin. The covered strand 34 was passed vertically through a settling room and there subjected to a powerful but controlled vibration that distributes the resin evenly and completes the strand was penetrated. The strand was taken up over a variable speed roll 35 and formed into a usual device, not shown, to pick it up, to a furnace melting process to cut it and similar .

The composition produced by this method was subjected to a heat treatment at 160 ° C. for 5 to 30 minutes, depending on the desired degree of flow and then about 18.5 mm long pieces cut up and cut into an approximately 62 χ 13 mm large mold cavity into approximately 2 mm (80 mils) thick moldings.

The results obtained are summarized in Table I:

Table I. Graphite / polyimide composites

Bending +

Analysis of hollow modulus _r strength

Resin graphite spaces kg / cm ² χ 10 kg / cirr χ 10 "5 graphite type wt. % Vol.% VpI. G (p si χ 10 ~ ⁶ ) (, psi χ 10" 3) _

Modmor II 25 68 0.3 0.76 (10.9) 4.97 (Jl)

Modmor I 28.0 60.3 4.3 0.74 (10.5) 3.29 (47)

Modmor I 39.8 48.8 2.3 0.82 (11.7) 3.15 (45)

+ Wingspan to depth ratio 25: 1.

Example 2

The ".following process was used to prepare a composition used, which includes glass and granite threads, which with-

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- 17 part of a modified polyimide are connected to one another.

The apparatus and method correspond to those in FIG. 2 and the example described-

The resin consisted of the reaction product of 2.5 moles of N, N ^T -Bismaleimido- (4,4 ^r -diphenylmethane) and 1 mole of methylene di aniline

The Modmor type I graphite fibers were impregnated in a fluidized bed to a proportion of 45% by weight of resin and then cut into pieces about 12 mm long. Strands consisting of "E" glass were impregnated in the same manner and cut into pieces about 6 mm long. A composition of approximately 25 volume percent graphite, 25 volume percent "E" glass, and 50 volume 35 polyimide resin was made by mixing. The composition was formed under pressure into two bars that were approximately 62 approximately 13 mm χ of the thickness indicated. These strands were examined and the results are summarized in Table II below.

Table II spec.
weight Bending module,
kg / cijr χ 10 " ^b
(10 ~ ⁶ psi) and fabrics 8th)
3) Graphite glass / polyimide compound 1 * 855
1,740 0.69 (9.82)
0.58 (8.27) sample thickness
mm (mi Is) A.
B. 1.6 (63)
.2.2 (86) Flexural strength
kg / cm ² 10 "3
(10 "3 psi) 2.93 (41.
4.22 (60.

The theoretical maximum values for this composite, calculated according to the addition rule for mixtures and the actual Values for the Paser and the resin are: specific gravity 1.77, flexural modulus 0.64 χ 10 kg / cm (9.1 x 10 psi) and flexural

3 2 3

strength 4.7b χ 10 kg / cm (68 χ 10 ^ psi). True see in see Words; are obtained by applying the mixing rule to compounds consisting of 50/50 vol.% graphite / resin and glass / Resin consist. On this basis, the following values are true-

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apparent: specific gravity 1.74, flexural modulus 0.47 x 10 kg / cm ² (6.77 x 10 psi) and flexural strength 3.75 x 3/4 " ⁵ kg / cm (53.5 x 10 psi) The weight of sample A is a little too high because a little too much resin flowed out during the molding process, and after the molding cycle was set, sample B was obtained with the expected specific gravity.

For comparison purposes, the following Table III shows the actual values from testing sample B with the predicted for the expected and theoretical maximum values summarized:

Table III Graphite glass / polyamide composites

Flexural modulus flexural strength

kg / er χ 10 ~ ° kg / cm ² χ 10 "5 composites specific weight (10 ~ ° psi ) (10 ~ ^ psi)

predicted 1.74 0.48 (6.8) 3.77 (5 ¹ O

actually 1.74 0.58 (8.3) 4.20 (60)

theoretical 1.77 0.64 (.9.1) 4.80 (68)

The actual values are therefore higher than those due to the application the mixing rule1 expected values.

Example 3

A high strength molded composite was made in an apparatus produced as it is shown somewhat schematically in FIG.

Graphite fiber strands or cord 20 (from Morgan's Modmor Type I) were passed through a tube furnace 42 (or over a hot plate) at temperatures above 500 C. A series of Rollers 44 supported the flattening of the fiber bundle strand before it was guided into the chamber 26 via the roller 46. The electrostatic forces of the surface charge separated the threads apart as they go down into bed 32

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from powdered polyimide resin, which by means of dry Air and vibration were moved and whirled up. An open roller 48, which consisted of five spindles, provided a maximum The resin particles made contact with the strand while exerting minimal resistance on the delicate threads the end. The powder-impregnated strand became vertical through a settling space above the dense phase of powder particles moved upward and controlled high frequency vibration via an attachment 40 attached to the frame of the chamber exposed. The vibration removed excess, loosely held, large resin particles. Resin uptake of 37 and 40% by weight was achieved, and then the strand Leave in an oven at 160 C for 5 to 30 minutes and then cut into pieces about 18 mm long (this is the mold length for a one-sided molding).

The compositions partially became at 210 kg / cm and 225 ° C oriented in a hollow shape of about 12 mm χ about 63 mm in size and randomly and unilaterally oriented in a hollow shape of about 56 χ about 63 mm in size and the density (according to ASTM D-792), the flexural strength, the flexural modulus (according to A3TMD-79O), the short-arm shear force (according to ASTM D-2344), the Izod impact strength (according to ASTM D-256) and heat resistance measured. the Results are summarized in the following Table IV:

Table IV
Properties of graphite (Modmor I) / polyimide composites

orientation coincidentally partially one-sided Fiber loading, Vol? 48 52 52 Resin content, wt.% 40 37 37 Void content, Vol. St - 2 ^ 2 ^ 2 Density, g / cm 1.59 1.61 1.61

2 0 98 2 U / 07? H

orientation - .. coincidentally + 0.56 ( partially + 0.91 ( one-sided + -. - Flexural strength Short arm shear T 8.0) 13) T 1.05 10-5 kg / _C ni2 10- ⁵ kg / cnr (10 ³ psi) T 0.64 ( + 0.21 ( + 15) (103 psi) 24 C (75 ° F) T 9.1) 3) T 0.46 24 ° C (75 F) 2.90 4.76 8.47 6.5) (4l, 4 (68 + (121 260 ° C (500 ° F) 3.25 + 0.13 4.20 + 0.09 8.54 + (46.4 T 1.9) (60 + + " 1.3) (12 2 + " 0.1 Flexural modulus ^ T 0.16 + " 0.07 ■ T 1.4) 10 ⁶ cg / cm ² (10 ° psi) T 2.3) T 1.0) T 0.02 24- ° C (75 F) 0.48 0.95 1.41 0.3) (6.8 13.6 20.1 260 C (500 P) 0.48 - 0.92 - 1.32 (7 (6.9 13.2 18.9 , 3) 0.51

Izod impact test,

notched

r-g mm (80 mils),

kg (ft.Ib./in.),

24 ⁰ C (75 ⁰ P) 26.4 (4.8) 45.7 (8.3) 77 (14)

The data presented in Table IV show that the graphite fiber reinforced composites of the present invention retain about 100% of their room temperature flexural strength and flexural modulus when heated to 260.degree.

Example 4

The procedure of Example 3 was followed along with preheating in a tube furnace at 650 and 750 ° C and using of graphite strands or cables made of Modmor type I and Hercules type HM-S repeated. Further, the procedure of Example 3 was followed along with preheating on hot Plate (shoe) at 520 and 550 C and using continuous Carbon / graphite strands from Modmor Type II and Hercules HP-S repeated. Finally the procedure of Example 3 using a continuous strand ^ Modmor Type I and "E" glass repeated according to previous

Heat pretreatment in a tube furnace at 550 ° C at the same time

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impregnated with powdered polyimide. In all cases, the compositions made high performance composites be shaped.

Mt Hercules HT-S graphite fibers after an oven treatment of 18 minutes at 160 ° C and a piece length of about 25 mm (the Mold length for one-sided molding) the following data summarized in Table V were obtained:

Table V Properties of carbon / graphite (Hercules HT-S) ZPoIy-

imi d-verb unds toffen

Orientation coincidentally partly one-sided

Fiber loading, VoI, % 53 53 53

Resin content, wt.% 39 38 39

Void content, vol. % 0, ^ 0.9 0.9

Density g / cm ³ 1.53 1.53 1.53

Flexural strength

kg / cm ² χ 103 (io ⁵ psi) 3.01 + 1.05 6.37 + 1.47 13.53 + 0.75

24 ⁰ C (75 ⁰ F) O3 + 15) (91 + 21). (193 + 9.7)

260 ⁰ C (500 ⁰ F) 3.08 + 0.56 5.04 + 0.56 13.23 + 0.33

(44 7 8) (72 T 8) (189 J_ 4.7)

Bending modul _{fi fi} -

kg / cm ² χ 10 ° (10 ° psi)

24 c (75 F) 0.37 + _ 0.07 0.97 +. 0. -13 1.08 + _ 0.04

(5.3 i 1.0) (13.9 + 1.8) (15.4 '+0.5)

260 c (500 F) 0.46 + 0, -15 0.85 i 0.08. 1.10 + _ 0.04

(6.6 Ϊ 2.2) (12.1 + 1.2) (15.7 + 0.5)

Short arm shear

kg / CiIi ^ χ 10 ^ (10 ³ psi)

24 ⁰ C (75 F) - - 0.64 (9.1)

Izod impact test,

notched

1.4 mm (65 mils),

kg (ft. lb: i ./.in.),

24 ⁰ C (7 ¹ J ° F) 42.9 (7.8) 56.2 (10.2) I6I (29.3)

hot ^ piel b

From a polyimide resin, which is the reaction product of 2.5 Mo-

209824 / 072A

len N, N'-bismaleimido- (i |, 4'-diphenylmethane) and 1 mole of methylenedianiline comprised 17.5 parts with 65 parts cut, about 6 mm long glass strands (Pittsburgh Plate Glass PPG 57 ~ C) mixed. The mixture is in an oven at 160 ° C. for 2 minutes melted and cooled. Any lumps that had melted together were broken.

To the mixture was added 17.5 parts of the same polyimide containing 2..Gew.52 carbon black. The mixture was tumbled, then melted in the oven at 160 ° C. for 2 minutes and the fused lumps were broken up again. The preimpregnated material of Example 3, cut to about 18 mm and made from Modmor I as described, was mixed with the glass-filled preimpregnated material and sufficient polyimide resin of the type described above in a drum to produce a composition with 55 ₃ 4 % by volume resin, 22 Vol. % Glass and 22.6. Vol. % Graphite fibers with a high modulus (the corresponding weight percentages are 41, 6, 32.5 and 25.9). The mixture was held in an oven at 160 ° C for about 15 minutes.

Then the composition was molded into a hollow shape of about 12 χ 63 now size with partial orientation and in a hollow shape of about 56 χ 63 mm in size with random orientation, with a pressure of 210 kg / cm and a temperature of 225 C at a thickness of about 6 mm until it was cured. The concentration (according to ASTM D-792) -, the flexural strength (according to ASTM D-790), the Izod impact test (according to ASTM D-256) and the coefficient of linear expansion (according to ASTM D-696) were measured. The following values, summarized in Table VI, were obtained:

20982ΛΛ072Α

■ Table VI

Properties of graphite-glass / polyimide composites Orientation coincidentally partially

Density, g / cm ³ 1.75 1.75

Flexural strength,

kg / cnr χ 10 ³ (IO '' psi)

24 ⁰ C (75 ⁰ F), 3.45 + 0.60 4.65 + 0.57

(49.3 + 8.4) (66.4 + 8.2)

260 C (500 F) x 2.49 + 0.52 3.33 + 0.23

_oo (35.5 + 7.4) (47.6 + 3.3)

300 ⁰ C (575 F). 2.35 +. 0.43 2.93 + 0.18

(33.5 + 6.1) (4l, -8 + 2.5)

Bending modulus cc

kg / cm ² χ 10 ° (10 ° psi) -

24 ⁰ C (75 ⁰ F) - 0.47 + 0.14 0.69 + 0.10

(6.8 + 2.0) (9.8 +1.4)

260 C (500 F) ■ 0.36 + _ 0.15 0.50 + _ 0.06

ο _ο ■■■ (5.2 + 2.2) .. (7.1 + 0.9)

300 C (575 F) 0.40 + _ 0.15 0.48 + _ 0.02

(5.7 + 2.1) (7.8 + 0.3)

Izod impact test, notched

1/4 "T, kg (ft. Lbs ./in.),

24 ⁰ C (75 F) 222 (40.5) 277 (50.3)

linear expansion coefficient, 24 - 300 ⁰ C (75 - 500 ⁰ F),. ...

to the shape direction. rr

cm / cm / C (in./in./ ⁰ F) 4.68 χ ίο "; 2.34x \ Q,

(2.6 x _; 10 " ^b ) (I ₃ 3 χ 10)

The above data show that those made in accordance with the present invention Composites have excellent thermal properties and high Have strength. . ,

On the other hand, the glass fibers can also be continuously impregnated by means of the fluidized bed technique of Example 3 and then in short pieces are cut up.

In addition, instead of a thermosetting polyimide resin, a powdered thermoplastic resin such as an aromatic resin can be used Polycarbonate, such as that obtained from bisphenol-A and phosgene, find use in the present invention.

Example 6 . -.

A composite of fibers and resin is made using a continuous in-line filament winding technique manufactured. - '"

The procedure of Example 3 is i \ ^r iederholt except that the impregnated strand as it comes from the vibration zone with high-frequency, is not cut. Instead, it is fed continuously to a filament winding apparatus as shown in FIG. After passing the roll 35, the continuous strand is guided through the guide 52 via a device 50 for adjusting the height of the winding (level wind device). The strand is wound on a 14.6 cm (5.75 inch) mandrel 56, coated with a mold release agent, and preheated to 110.degree. After the appropriate number of layers have been applied, winding is stopped and the sleeve or tube of windings 58 is heated on a rotating mandrel to about 170 ° C until it is fully cured, which takes about 3/4 hour. The mandrel is cooled and the composite, which is in the form of a sleeve or tube, is braced. Optionally, the impregnated strand, before it is wound up, can pass through a tube furnace 42 or a hot one. Plate "of about 160 · - C z-.B. Be slid in order to preheat the resin Ak, to melt it and to reduce its viscosity.

Also shown in Fig. 6 is an air cannon 54 which is used to regulate the temperature of the prepreg material as desired and a heating unit 60, such as a calrod unit, to provide external heat for the workpiece 58 and the mandrel 56 to create. '-

209824 / 072A

Claims (1)

Claims 1.) Process for the production of an existing one from fibers .. and resin Composite, marked through the following stages: continuous passing through of at least one of many Threads of existing strand through a fluidized bed of pulverized Resin to impregnate the strand or strands with the resin, '" Passing the impregnated strand or strands into a zone High frequency vibration to evenly distribute the powdered resin on each of the filaments and Removal of the strand or strands treated in this way from the called zone. 2. The method according to claim 1, characterized that the resin is a thermosetting resin. 3. The method according to claim 2, characterized that the resin is a polyimide resin. 4. The method according to claim 1, characterized in that the one or more threads consisting of many threads Strands of carbon, graphite or glass threads include. 5. The method according to claim 1, characterized that the one or more is made up of many threads Strands comprise a mixture of graphite and glass threads. . Method according to claim 1, characterized that the treated strand or strands are passed into a Heizzonti to melt the resin and encapsulate each of the monofilaments and that or the 209 & 74/0774 en so treated strands afterwards in for the shape / suitable Lengths are cut. 7. The method according to claim 1, characterized that one passes the strand or strands consisting of many individual threads through a gas jet to loosen and widen the threads and that the loosened strand or strands are passed over rollers to the Loosen and unravel the threads further before you lead them into the fluidized bed. 8. The method according to claim 1, characterized that one or the strands consisting of many single threads through a heating zone together with conducts a free flowing gas in order to clean the threads and their surface with a maximum force of attraction for the resin in the fluidized bed to be provided before the threads treated in this way are introduced into the fluidized bed. 9. The method according to claim 8, characterized .that. the heat-treated strand or strands are passed over rollers in order to flatten them before the the threads in the flattened strand or strands in the fluidized bed directs. 10. A method for producing a composite material comprising glass fibers, marked by following steps: continuously passing through at least one of many Strands of existing strand, the carbon, graphite, glass or a mixture thereof, through a heating zone together with a free flowing gas to clean the filaments and to provide their surface with a maximum attraction for the powdered resin, Passing the heat-treated strand or strands therethrough a fluidized bed made of powdered, thermosetting polyimide 209824/07? A resin in order to impregnate the strand or strands with said resinj Directing the impregnated strand or strands into a high-frequency vibration zone, to evenly distribute the powdered resin on each of the filaments and Removal of the sirong (s) treated in this way from the aforesaid Zone . 11. The method according to claim 10, characterized in - "" ■ -. draws that one heats the strand or strands, to melt said resin and promote its polymerization. 12. The method according to claim 10, 'characterized in that one or the treated with resin Strands passed through a heating zone to melt the resin and promote its polymerization and that one cut the strand or strands so treated into lengths suitable for shaping. 13. The method according to claim 10, characterized that the resin-treated strand or strands are cut into lengths suitable for shaping, and "The cut lengths are heated to melt the resin and promote its polymerization. I ¹ I. Pre-impregnated composition which is suitable for heat conversion into a fiber-reinforced resin composite Λ eigfrefe-i "3 _ $>_-; .wqbei the composition comprises at least one yielen ^from% \ threads existing strand and each of the individual threads in the or the strands having a substantially continu- • ous layer comprising a sheath around each of the. Forms monofilaments and wherein the layer comprises a resin which is melted in place on each of the monofilaments while these together form the strand or strands. 20 9824 / (17? A., -. 15. Composition; overall Ik according to claim ₃ characterized _indicates} that the resin is a thermosetting resin. 16. The composition according to claim 15 characterized denotes overall _{S, 3} that the resin is a polyimide resin. 17. Composition according to claim 1 ^ _3, characterized in that the one or more strands consisting of many threads comprise carbon, graphite or glass thread. 18. Composition according to claim Ik _3, characterized in that the strand or strands comprise a mixture of graphite and glass thread. 19. Pre-impregnated composition necessary for heat conversion in a composite made of fiber reinforced resin, wherein the composition is at least one comprises a multi-filament strand in which each of the individual filaments has a layer of particles around the filament, wherein the particles are comprised of an in-situ meltable resin to form a substantially continuous To form a layer on each of the monofilaments while they are in the strand or strands. 20. Composition according to Ansoruch 19, characterized in that the resin is a thermosetting resin. _: . - 21. Composition according to claim 20, characterized. that the resin is a polyimide resin is. 22. Composition na'cii claim 19, Ί] adurc ti g ο indicates that the one or the other from many 209824/0774 BATH Threads consisting of strands of carbon, graphite or glass thread include. 23. Composition according to claim 22, characterized in that the or the strands one Include mixture of graphite and glass threads. 24. A method of manufacturing one consisting of fibers and resin Composite by continuous row-shaped Winding up a thread, marked by the following steps: continuous passage of at least one strand consisting of many individual threads through a fluidized bed powdered resin to impregnate the strand or strands with said resin, Guiding the impregnated strand or strands into a high-frequency vibration zone, in order to evenly distribute the pulverized resin on each of the strands, winding the impregnated strands in a predetermined one Patterns on a mandrel to form a core made of coils and . Heat the coil-made sleeve to form the resin to melt and form the composite. 25. The method according to claim 24, characterized e i c η η e t that the resin is a thermosetting resin. 26. The method according to claim 25 »characterized geke η n- · /, eich η et that the thermosetting resin is a polyimide; 51. 27. The method according to claim 25, characterized in that the impregnated strands are continuously passed through a heating zone in order to melt the resin and promote its polymer Lon after the ;; trang au ;; removed from the high frequency vibration zone and before winding it onto said mandrel. 20982 4/072 '·' BATH ORIGINAL so Blank page