FI81298B - ANORDNING FOER BELAEGGNING AV EN FOER MANTELMATERIALETS EXTRUDERINGSTEMPERATUR KAENSLIG KAERNA MED EN MANTEL, ETT FOERFARANDE FOER FRAMSTAELLNING AV ETT COMPOUNDMATERIAL SAMT ANVAENDNING AV DESSA FOER FRAMSTAELLNING AV PLASTF - Google Patents

Abstract

1. A device for an extruder for sheathing a core sensitive to the temperature of extrusion of the sheathing material consisting substantially of a tool comprising a tubular extrusion plate (1), an extrusion die (2) and a tubular guide (3), having a means (4) providing the possibility of cooling arranged so that its end abuts substantially in alignment with the outlet mouth of the tool forming the internal wall of the sheath, whilst leaving a channel (5) for a cooling medium between the said guide and the tool, which may reach as far as the outlet channel (6) of the material in the tool, characterized in that the end of the guide is terminated by a nozzle pierced by lateral holes.

Description

1 81298

The present invention relates to an apparatus for extruding a jacket-sensitive core. More specifically, it is an extrusion head that can prevent the core from being exposed to too high a temperature, which could cause it to be damaged when it comes in contact with the jacket at the outlet of the extrusion tools.

The invention also relates to a process for the preparation of a composite by extruding a sheath around a core as defined in the preamble of claim 10. This core can be, for example, a plastic powder, one or more plastic fibers or also one or more metal, mineral or organic fibers impregnated or coated with a plastic powder.

The invention also relates to the use of this apparatus and method for the production of sheathed fibers as defined in claim 16.

U.S. Patent 3,239,884 describes an apparatus for coating a heat-sensitive cable li. The equipment for coating the cable with a sheath consists of a set of tools represented by a tubular nozzle and a pusher, and a tubular cable guide. This guide, equipped with an internal cooling device, is arranged on the axis of the outlet edge forming the inner wall of the tool set jacket, while ensuring that a duct is left in which compressed air can be circulated or a vacuum can be created between the cable, guide and jacket, the cable and jacket junction and continuity between the guide tube and the channel.

If airflow is used as the coolant in this equipment, it will come into direct contact at the junction of the cable and sheath. Direct contact of the cooling air flow at this point is not detrimental in the case of a cable to be coated alone, since it is sufficient to adjust the air flow so that it does not interfere with the manufacture of the sheath.

The situation is quite different when it comes to forming a sheath for a core which is particularly brittle, either under the influence of heat or mechanically, such as in the coating of extremely thin bundles of fibers and / or powders. In the apparatus according to said patent 3 239 884, the air flow rate cannot be adjusted when the fiber bundles are provided with a sheath, and this causes unevenness in the sheath formation. The same is true when forming a jacket for powders which are trapped in either the guide or the deaeration duct depending on the direction of the air flow, which inevitably causes blockages at some point in the equipment, leading to breakage of the extruded material and worst case clogging of the material.

The apparatus and method according to the invention can remedy these disadvantages. The main features of the apparatus, method and their use according to the invention appear from claims 1, 10 and 16. The following description, based on the appended figure, illustrates the apparatus. It

II

3 81298 consists mainly of a set of tools represented by a tubular nozzle 1 and a plunger 2, the respective directions of movement of which can be reversed as shown in the figure, and a tubular guide 3, which guide is kept cooled by means of the system 4. the outlet end terminates at substantially the same location, and preferably on substantially the same axis as the outlet edge forming the inner wall of the tool set casing, i.e. substantially co-located with the pusher 2, but omitting a coolant channel 5 which may extend to the channel 6 from which the material exits the tool set.

The special feature of this guide is that it terminates at its outlet in a nozzle with holes on the side. In addition, the outlet channel of the nozzle, which is preferably on the axis of the outlet channel of the guide, is smaller in diameter than the inner diameter of the rest of the guide 3, while remaining larger than the diameter of the core passing through the guide. The advantage of such a nozzle, shown in black in the figure at the end of the guide 3, is that it can control the coolant, usually the air flow, coming from the duct 5. This coolant, which is partially or completely turned by the side holes of the nozzle, hits the core-forming material 14 and the jacket 6 formed in the channel 6 less strongly. Such an arrangement is particularly advantageous when a smaller or larger part of the core is powder. By moving the guide so that the nozzle end comes into contact with the pusher 2, the channel 5 can be completely closed, as shown in the figure, before the outlet forming the inner wall of the tool set casing. If the duct is completely closed, the coolant, which is turned by the nozzle side holes, returns to the guide without coming into direct contact with the jacket. There are at least two side holes and they are placed opposite each other; however, for good operation of the equipment, it is recommended to fit a hole ring around the nozzle.

4,81298

In a classical and easy-to-implement manner, a set of tools representing an extruder-presser unit is usually arranged as a corner end 7, the unit being fastened with a clamping screw 8. To improve the thermal insulation of the guide, the hot walls of the duct 5 can be lined with an insulator 9.

In order to minimize the effect of thermal radiation from the extrusion tools, it is recommended to immediately fit a heat shield 10 to the tool outlet, for best results using a shield starting at the outer edge of the tools. The efficiency of the shield can be improved by any additional cooling means, such as by sending an air flow from the pipe 11, which can also act as a counterpressure to the extruded material thanks to the air flow rate reducer 12. The entire equipment is suitable for a conventional extrusion machine and is used according to classical extrusion methods.

The end of the tubular guide 3, i.e. the outlet end of the nozzle, which is substantially at the outlet edge forming the inner wall of the tool set casing, may be before said edge, but may also open after said edge of the nozzle, as shown in the figure. Preferably, the distance from the nozzle outlet end to the pusher edge when the guide is retracted, or from the nozzle outlet end to the nozzle outlet edge when the guide goes outside the nozzle, is at most about 4 mm.

The apparatus can be used to produce, as already specified, a composite material consisting of a deformable sheath with a brittle core inside at the compression temperature of the sheath. According to the method, the thermoplastic jacket is pressed through the nozzle channel 13, while at the same time a core-forming substance 14 is fed from the end opposite the tool set of the guide 3, which may be cooled and acts as a filling funnel.

II

5 81298 after the series outlet, with a cooling system arranged substantially at the tool outlet between the jacket interior and the core-forming material so that the temperature of the tool or jacket does not affect the core at the outlet 6. In a practical, though not exclusive, cooling system 3 and the tool kit hot wall. In this case, either by pushing the guide forward into the outlet of the tool kit or by the degree of cooling of the inner outlet of the jacket, or a combination of the two, the temperature of the entire jacketed material can be kept low enough to substantially maintain its original appearance without substantial deformation.

To improve the calibration of the composite or even to increase its cooling rate, countercurrent air can be directed to the outer surface of the jacket as the jacket exits the tool kit. This can be done, for example, by spraying air into the pipe 11 of the heat shield 10.

According to the method in question, all extrudable thermoplastic resins can be used as the jacket. They can be selected, for example, from styrene, vinyl, acrylic or methacrylic, or olefin polymers or copolymers, or also from fluorinated resins, polyamides, polycarbonates, cellulose propionates and mixtures of these compounds.

The materials used as the core can be selected from thermoplastic resins that can be used to make the sheath. They can also be selected from any powders or fibers whose physical appearance or structure can be degraded at jacket extrusion temperatures. This may be, for example, a non-crosslinked thermosetting resinable powder, such as a non-crosslinked polyester powder.

The core can be provided with a sheath directly when it is in powder form, but also in fiber or granular form. According to another feature of the invention, the sheath can be provided with any fibers which are impregnated with a powder of resinable resin or which are otherwise reactive.

Thus, for example, organic or inorganic fibers, such as textile, carbon, glass or other fibers, can be coated. Such fibers impregnated with a mouldable resin powder are known per se and can be prepared, according to a classical method, by using the fibers in a liquid bath of the powder, as described in EP 0 133 825. When the sheath is provided with structures consisting of a deformable resin powder and resin powder impregnated or unsaturated fibers, this structure or impregnated fibers 14 are fed into the guide tube which meet at the outlet of the sheath nozzle after being separated from this sheath by some cooling member 5. Generally, cooling is provided by providing an air flow between the core and the inner wall of the sheath.

The following examples illustrate the invention without, however, limiting it.

Example 1

From a single-screw extruder with a length of 30 to 24 D and equipped with a tool set according to the attached figure, the die is extruded at a speed of 760 grams / hour at a tool set compression temperature of 220 ° C, a polyamide 6 jacket with a diameter of 2 mm and at the same time a 320 tex roving yarn, the yarns of which are pre-embedded in a polyamide 12sa having a melting point of 176 ° C and having a particle size of about 10 microns 7,81298 kroons, is fed through the water-cooled guide 3 to the jacket.

The fiber / powder to volume ratio is 25/75. In the duct 5, air is circulated at a rate sufficient to cause the powder to liquefy near the jacket formation zone.

Example 2

With the apparatus of Example 1, a polyamide 6 jacket with a diameter of 2 mm is extruded at a speed of 860 grams / hour in a tool at a compression temperature of 225 ° C. texin rovinglan-kaan. The fiber / powder volume ratio is 46/54.

A combination of polyamide 6 and azodicurea is obtained, which is reinforced with fibers which can be subsequently heat-treated to take advantage of the swelling effect of azodicurea.

Example 3

Repeat Example 1 using:

- tool temperature 225 ° C

- a sheath of polyethylene with a melting point of 117 ° C - a compression rate of 1025 grams / hour.

It is fed to the jacket to form a roving yarn impregnated with powdered dicumyl peroxide having a reaction temperature of 120 ° C. The fiber / powder volume ratio is 35/65.

A composite product is obtained which can be crosslinked later in heat.

Example 4

Example 1 is repeated using: 8 81298

- tool temperature 210 ° C

- polyamide 12 sheath - compression speed 800 grams / hour.

It is fed to the sheath to form a roving yarn impregnated with polyether blockamide powder having a melting point of 128 ° C. The fiber / powder volume ratio is 43/57.

A composite material is obtained which can be heat treated to improve the ultimate flexibility of the polyamide 12 thanks to a suitable polyether.

Example 5

Example 4 is repeated replacing polyether blockamide with polyamide-12.

A polyamide 12 sheath is obtained which contains glass fibers impregnated with polyamide 12 powder and which can be subsequently post-processed into a final product reinforced with glass fibers.

Claims (16)

An extruder apparatus for coating a core sensitive to the jacket compression temperature with a jacket, the apparatus consisting essentially of a tool comprising a tubular die (1) and a pusher (2) and a tubular guide (3) optionally having a cooling device (4) and is arranged so that its end terminates substantially at the same point as the outlet edge forming the inner wall of the tool casing, leaving a channel (5) for coolant between the guide and the tool, which may extend all the way to the channel (6) from which the material exits the tool, known that the end of the guide ends in a nozzle with side holes. Apparatus according to claim 1, characterized in that the outlet channel of the nozzle is smaller in diameter than the inner diameter of the rest of the guide (3). Apparatus according to claim 1 or 2, characterized in that the nozzle end is substantially at the outlet edge forming the inner wall of the tool casing. Apparatus according to claim 1 or 2, characterized in that the nozzle is substantially on the axis of the outlet edge forming the inner wall of the tool casing. Apparatus according to one of Claims 1 to 4, characterized in that the nozzle head is in contact with the pusher (2). Apparatus according to one of Claims 1 to 5, characterized in that the distance from the nozzle outlet end to the edge of the pusher (2) when the guide is retracted or from the nozzle outlet end to the nozzle (1) outlet edge when the guide extends outside the nozzle is at most about 4 mm. 10 81 298 Apparatus according to one of Claims 1 to 6, characterized in that a heat shield (10) is arranged at the outlet of the tool. Apparatus according to Claim 7, characterized in that the thermal protection begins at the outer edge of the tool. Apparatus according to Claim 7 or 8, characterized in that the heat shield forms a cooling element. 9 81298 A method of making a composite by extruding a sheath around a core, comprising passing the core-forming agent through a guide (3), optionally cooled, the core-forming agent and optionally the inner wall of the sheath at the tool outlet, before contacting each other, is cooled by a cooling system located between the tool and the guide, characterized in that the cooling air is at least partially ducted inside the guide (3) through a nozzle with side holes arranged at the end of the guide to protect the jacket's compression temperature sensitive core. Method according to Claim 10, characterized in that the cooling air is prevented from acting directly on the jacket at the outlet of the tool by bringing the nozzle head into contact with the pusher (2). Process according to Claim 10 or 11, characterized in that the sheath-forming agent is chosen from thermoplastic resins. Process according to one of Claims 10 to 12, characterized in that the core of the composite is selected from malleable resins in the form of powders, fibers 1: 11 8 988 or granules, or fibers impregnated with a malleable resin. Process according to Claim 13, characterized in that the deformable resins are selected from non-crosslinked thermoplastics or thermosetting resins. Method according to Claim 13 or 14, characterized in that the fibers impregnated with the deformable resin powder are selected from glass or carbon fibers. Use of an apparatus and method according to claims 1-15 for the production of fibers coated with a thermoplastic resin jacket impregnated with a jacket compression temperature, which is impregnated with a moldable resin powder.