JPH0315524B2 - - Google Patents

Abstract

Process for manufacturing finished articles consisting of continuous reinforcing fibres connected together by a thermoplastic matrix, characterised in that it comprises the following steps: - introducing particles of thermoplastic powder into the core of a continuous roving of fibres; - covering the said roving by means of a layer of plastic whose melting point is below that of the powder particles and by operating at temperatures such that the imprisoned powder particles cannot melt and continue to flow freely between the fibres; - stacking the flexible profiles thus obtained in several layers so as to produce the desired shape of the finished articles; - heat-treating the stack obtained; - cooling and solidifying. Application to the manufacture of components by filament winding, pressing and reinforcement of moulded components.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of a mineral, organic or metallic continuous fiber roving impregnated to the core with a thermoplastic powder and coated with a flexible coating - in which case the thermoplastic powder The melting point of is greater than or equal to the melting point of the flexible coating - for composites.

This new composite material has already been described in the applicant's French Patent No. 8310632. However, in this patent, the melting point of the powder impregnating the fibers is limited to a level significantly higher than the melting point of the dressing.

The main feature of the new composite material according to the invention is its flexibility. For example, the composite materials belonging to the prior art, as defined in French Patent No. 8121545, are flexible but rigid materials. They are 5-10mm wide,
It has the shape of a stop with a thickness of about 1 mm, and is melted and
Contains continuous parallel fibers such as reinforcement that is cool solidified or tightly embedded in a thermoplastic matrix.

Although this type of material is obviously hard,
Experience has shown that it breaks when bent.

This disadvantage arises when the material is used around metal objects with a small bending radius (e.g. radius 8-10 mm), such as automotive parts (steering wheel frames, hydraulic cylinders, etc.).
etc.), it becomes a big handicap. The aim of the invention is to overcome the aforementioned drawbacks.

In the method of manufacturing thermoplastic flexible composites of the present invention, rovings of continuous parallel (i.e., unkinked) fibers are given their properties, i.e., each constituent fiber is placed in a fluidized bed of thermoplastic powder particles. Thermoplastic powder particles are impregnated using the property of instantaneously spreading when crushed. The powder particles can be prepared using known techniques (electrostatic generators, friction brushes or rollers,
(e.g.), it collects around each fiber in the roving due to the static electricity generated.

When the individual fibers to which the thermoplastic fine powder is attached are collected, a roving of parallel fibers is obtained, the core of which is impregnated with the fine powder, and the periphery covered with a layer of the same fine powder.

The roving with the thermoplastic fines attached is then extrusion coated or dip coated with the solution or dispersion to form a continuous thermoplastic coating layer. This allows the powder particles and fibers to mix freely within the coating layer.

This method makes it possible to obtain a composite material that remains flexible and can even be bent and tied without breaking. Therefore, these flexible composites are braided,
Suitable for weaving and knitting operations, this creates a wide range of fields of use - fields of use that go beyond those of the prior art products with the aforementioned brittleness when bending.

Flexible composites can be made with reinforcing fiber contents of up to 50% by volume and 70% by weight.

The reinforcing fibers may preferably be glass fibers of 160 to 320 tex when coated with common polymers such as those listed below.

Fibers of 1200 to 2400 tex have been used when coating very high flow polymers such as those listed below.

Other fibers include aramids (superpolyamides with aromatic bases) such as Kevlar fibers. In that case, for example, one of 1580 decitex is preferable. The coating uses the same type of polymer as for glass fibers.

Finally, carbon fibers, the size of which is indicated in filaments (actually kilofilaments), may also be used. Filament sizes of 3 to 12 kilofilaments are most suitable for producing the flexible composites of the present invention.

Among the fine powder resins used to impregnate the continuous fiber rovings to the core, the most suitable for carrying out the present invention are polyamide powders, i.e. lactams (caprolactam, lauryllactam, etc.) or amino acids (adipic acid and hexyl lactam). These include salts of methylene diamine, polycondensates of aminoundecanoic acid, and polyamidic copolymers.

However, other thermoplastic powders - such as those of polypropylene, polyethylene, polyvinyl chloride, polyester homopolymers and copolymers, polyvinylidene fluoride, etc. - can obviously be used.

The coating operation for continuous rovings to which fine powder has been added, which is a feature of the present invention, can be carried out without heating the fine powder particles to their melting point.

This coating operation requires 6/6.6/12 with a melting point of 105°C.
A resin having a lower melting point than the powder, such as a terpolymer, or a resin of the same type as the powder but with a lower viscosity that can meet the requirements of the extrusion coating process is used.

These resins include polyamides 6, 11 and 1.
2. There are polypropylene, polyethylene, polyvinylidene fluoride, and polyester.

According to one embodiment of the method for producing thermoplastic flexible composites of the present invention, the expanded rovings are first bathed in an aqueous or organic bath in which fine powder is dispersed, as described in the applicant's French Patent No. 8103528. Impregnated with the fine powder, it is then dried.

According to another method of implementation, the roving containing powder particles can be coated using any of the following technical methods within the scope of the invention.

o Pass the roving through a device containing the molten coating.

〇 The roving is coated with the first liquid monomer or oligomer.
bath and then through a second bath containing liquid monomers or oligomers that react with them to form the thermoplastic. The combinations of materials in the first and second baths include polyol-polyisocyanate (resulting in polyurethane), polyurethane-polyurea,
These include epoxy resin and curing agent, epoxy resin-dicarboxylic polymer, etc.

The invention also includes an apparatus for actually achieving its objective - the production of flexible composites containing continuous fiber rovings impregnated to the core without melting with thermoplastic fines.

Other characteristics and advantages of the invention will become apparent from the following description using comparative examples and examples of various methods of assembling the device according to the invention. The description will be made in conjunction with the accompanying drawings below.

FIG. 1 is a longitudinal cross-sectional view of the apparatus; FIG. 2 is a cross-sectional view of the coating die; FIG. 3 is a cross-sectional view of an object manufactured according to the invention in a burst strength test apparatus; FIG. 4 is a cross-sectional view of a flexible material manufactured according to the present invention.

The actual operation of the method for manufacturing a flexible composite material of the present invention is carried out as shown in FIG. The continuous fiber roving 1 is sent out from an unwinding reel by the tensile force generated by guide rolls 2 and 3. The roving passes through an airlock 7 into a completely sealed fluidization tank 4. Here, the thermoplastic fine powder 5 is in a fluidized state due to the compressed air 6 entering at the bottom. Although not shown in Figure 1, the French patent
Using conventional equipment such as rollers or splined cylinders, as described in No. 8310632,
The roving is spread out or loosened. The roving becomes electrostatically charged against these devices due to friction and then passes, coated with fines, to the fluidization tank outlet, ie to another aerodynamic tank 8.

The airlock 8 is characteristically integrated with the fluidization tank and the coating crosshead 9 via two heat seals 16, 17 shown in FIG. The presence of these seals minimizes heat exchange between the airlock 8 and the coating crosshead 9 (which provides a heat source for active heating (not shown)) and the end of the fluidization tank 4. This thermal insulation prevents melt-gelling of the powder in contact with the hot surface. In the preferred system type, insulating seal 16 is fabricated from "Teflon" (polytetrafluoroethylene) plate and insulating seal 17 is pressed from sintered zirconium oxide.

The connections between the fluidization tank 4, the aerodynamic tank 8, and the crosshead 9 are made airtight in order to prevent powder particles from leaking out of the device and from burning the particles.

of powder particles that are not electrostatically attached to the roving.
In order to more easily achieve complete backflow to the fluidization tank, a low flow pump 15 is used to pump the aerodynamic tank 8.
Create some airflow inside. This pump is of the roller type supplied by Ets.W.BACHOFEN of Basel for laboratory use.
The air pressure that this pump can provide is 0.10-0.30 bar. A minimum air flow, a so-called "foaming" air flow, can be obtained by reducing the rotational speed of the roller rotor on the pump, which acts to compress the air in the hose.

Although not shown in Figure 1 to avoid complexity,
A small cyclone is installed, which allows
The excess air supplied by pump 15 is allowed to escape and a small amount of powder carried with this air is recovered. The roving, thoroughly impregnated and coated with fine powder, is introduced into dies 9, 9' at the outlet of airlock 8.

In order to prevent the powder from being in prolonged contact with the metal of the crossheads 9, 9' and melting into a gel, it has been found expedient to provide a wire guide 19 with a large inlet.

When sheathing power transmission and telephone cables having the same cross-section as the roving, it has been found to be expedient to provide an inlet with a cross-section 1.5 to 3 times that normally used for wire guides.

The crossheads 9, 9' are supplied with plastic coating by an extruder 10, shown as a barrel/die connection. This plastic coating leaves the die in the form of a so-called sleeving. That is,
The exit diameter of the plastic coating is determined by a mandrel having a diameter larger than the outer diameter of the roving, and the molten coating then contracts on the profile leaving the die and comes into contact with the roving approximately 5 mm from the exit. .

The coating head is advantageously positioned along the longitudinal axis. The shape cools down most of the time when it moves through the air for about 1 meter. The profile remains flexible after cooling and moves on a pulley with 11 slots and a diameter of approximately 600 mm. This profile is made of fiber rovings 33 impregnated with thermoplastic powder 32 and further provided with a flexible coating 31, as shown in FIG.

Example 1 Orgasol manufactured by the applicant
A 320 tex roving loaded with 1002 fines is extrusion coated with a coating of Applicant's Rilsan AMNO resin. The characteristics of the product are as follows.

Fine powder polyamide 6 Bulk density 0.50 Melt index 20 to 60 (at a load of 1 kg)
(Measured at 235℃) Covering material Polyamide 12 Density 1.5 Melt index 10-40 (at 2Kg load)
Measured at 190℃) Glass fiber Density 2.40 Maillefer extruder φ30 coating die Type die diameter used for sleeving method
3.5 mm Mandrel diameter 2.9 mm Wire guide diameter 1.5 mm Inlet diameter 2.4 mm Die temperature 195°C Drawing speed 100 m/min The obtained flexible composite material has the following properties.

Fine glass fiber coating % by weight 75 11 14 % by volume 47 33 20 Example 2 (Fig. 3) The composite material according to the invention can be used for reinforcing injection molded plastic parts used for example in hydraulic cylinders under high internal pressures. use

Such parts, for example, have a length of 100 mm and an inner diameter of
Consists of a cylinder with a bottom of 16 mm and a wall thickness of 4 mm.

For comparative testing, these parts can be made using the following four techniques.

Parts injection molded in polyamide 11 mixed with short glass fibers (Rilsan ZMO of the applicant).

Parts manufactured from the same mold and using the same plastic. Then, prior to injection, a single layer 23 of the flexible composite material was placed on the core of the mold in the same manner as in Example 1, and the composite material was wound loosely in a spiral around the core.

Parts manufactured in the same way. During the winding process, a tension of 2 dan was applied to the composite material.

Parts manufactured in the same way. There are two layers of composite material, and the tension during winding is 2 dan.
maintained.

In order to measure the bursting pressure of parts manufactured using the above four techniques, a hole is made in the cylinder 21,
A fitting 22 connects the cylinder with a liquid under pressure. A piston 24 with a lip-shaped seal 25 moves freely within the bore of the cylinder.

For burst tests, this piston shall always be made of steel. The device consisting of a plastic cylinder and a steel piston is mounted on two plates 26, 26' and 2.
It is placed in a rigid frame formed by the book uprights 27, 27'.

Connect the dynamometer 28 to the piston rod and plate 26'
Place it between.

The wave train pressure can be determined from the measured bursting force using the following equation.

F=pS In this case, the cross section S is given by the size of the selected bore.
It is 2×10 ^-4 m ² . Under the above conditions, the average burst pressure is: Sample bursting force (Dan) Bursting pressure (GPa) 400 2 450 2.25 1000 5 1100 5.5 In this way, it is clear that the mechanical strength of flexible composites is improved, especially when rolled under tension. It is divided into Furthermore, it can be seen that when the winding diameter is reduced, only the flexible composite of the present invention is suitable for winding operations.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the apparatus, FIG. 2 is a sectional view of the coating die, and FIG. 3 is a sectional view of an object manufactured according to the present invention placed in the apparatus for burst strength testing, FIG. 4 is a sectional view of a flexible material manufactured according to the present invention. 1... roving, 2, 3... guide roll, 4...
Fluidization tank, 5... thermoplastic powder, 7, 8... aerosk, 9... die, 10... extruder.

Claims (1)

[Scope of Claims] 1. A composite material comprising a flexible covering material covering fiber rovings impregnated with a thermoplastic powder, wherein the melting point of the thermoplastic powder is higher than or lower than the melting point of the flexible covering material. Composites that are the same. 2. The composite material according to claim 1, wherein the flexible covering material is selected from various thermoplastic resins. 3. Introducing a powdered thermoplastic material into the core and periphery of the continuous fiber rovings to coat the fibers, and then coating the whole with thermoplastic flexibility having a melting point lower than or equal to the melting point of the thermoplastic powder. A composite material manufacturing method characterized by coating with a covering material. 4. The method for producing a composite material according to claim 3, wherein the thermoplastic powder is selected from the group comprising polyamide, copolyamide, polyethylene, polypropylene, polyvinylidene fluoride, and polyester. 5 The thermoplastic flexible covering material is made of polyamide,
4. The method of manufacturing a composite material according to claim 3, wherein the composite material is selected from the group comprising copolyamide, polyethylene, polypropylene, polyvinylidene fluoride, and polyester. 6. The composite material manufacturing method according to claim 3, wherein the coating with the thermoplastic flexible coating material is performed at a temperature lower than the melting point of the thermoplastic powder. 7. The composite material manufacturing method according to claim 3, wherein the coating treatment of the roving with the thermoplastic flexible coating material is carried out using an extrusion method. 8 a supply means for roving, a fluidization tank having an inlet end and an outlet end through which the roving is fluidized and for fluidizing the thermoplastic powder, and a flexible covering for covering the roving impregnated with the thermoplastic powder. Apparatus comprising a supply means and a die for coating with a flexible coating, the inlet and outlet ends being substantially leaktight. 9. The apparatus of claim 8, wherein the die has a blowing chamber associated with the die and the fluidization tank. 10. The apparatus of claim 9, wherein the blow chamber is thermally isolated from the die and fluidization tank by an insulating seal. 11. The device according to claim 10, wherein the insulating seal is made of polytetrafluoroethylene or zirconium oxide.