FR2867100A1 - Raw material supplied into machine, for transformation of thermoplastic/elastomeric material, where the raw material is formed by continuously feeding a material to the machine, fractionating the material and/or melting the raw material - Google Patents

Abstract

Raw material supplied into a machine (preferably extrusion machine or an injection moulding machine), for transformation of thermoplastic or elastomeric material, where the raw material is formed by continuously feeding a material to the total capacity of the machine, fractionating the material when the level is up to the neck of the machine and/or melting the raw material inside the machine. Independent claims are also included for: (1) Method for supplying a machine, which transforms thermoplastic or elastomeric material, comprising providing the prepared raw material, supplying the material continuously into the machine, fractionating the material when the definite level is reached and/or melting the raw material inside the machine; and (2) machine (1) for transformation of plastic materials aimed to be put to work for the process comprising at least a device (12) permitting to maintain in continuity of the first material (10).

Description

The present invention relates to a raw material for feeding a

  thermoplastic or elastomeric processing machine, a method of feeding such a machine with this raw material and a material processing machine

  thermoplastics or elastomers adapted to use this raw material.

  A machine for transforming thermoplastic or elastomeric materials, such as an extruder or an injection molding machine, is most often made to produce series of pieces of different natures, these parts being able for example to be made of materials or compositions of materials. different, or in different colors.

  Feed raw materials for thermoplastic processing machines are usually in the form of powder (s) or granules to allow a rapid and homogeneous melting of these raw materials for subsequent processing to achieve. The machines are equipped for this purpose with one or more mixing hoppers of the different materials (base material (s), colorant (s), additive (s), etc.) forming the composition to be transformed, this or these hoppers being equipped with volumetric or weight dispensers, usually electronically controlled.

  By way of illustration, FIG. 1 shows an extruder 1 of known type, viewed from the side and in longitudinal section. This extruder 1 comprises a feed hopper 2 in the form of granules, a heated tube 4 in which a screw 5 for mixing and stuffing raw materials, a driving motor 6 for driving the screw 5 and a head 7 of extrusion of the material 8 according to the desired shape.

  The use of raw materials in the form of granules or powder (s) has the important disadvantage of requiring a thorough cleaning of the mixing hopper (s) and the dosers between each series of parts, in order to prevent granules and residual dust from the previous series of pieces do not pollute the material of the next series. This cleaning involves a tedious work to perform and immobilization of the machine the time of its completion. The machine must also operate for a certain period before the production of the following series of parts can begin, so that one is sure of the absence of residual particles or granules of the preceding series.

  Raw materials in the form of granules or powder (s) are more likely to spread around the machine, forcing a regular cleaning of the workshop.

  Moreover, some raw materials have demanding conditions of implementation, and must especially have a very low humidity or be mixed and melted in a low oxygen atmosphere. Otherwise, the qualities of the products obtained could be altered. The raw materials in the form of granules or powder (s) offer from this point of view important contact surfaces with the ambient air and therefore have the disadvantage of requiring in some cases treatments prior to their introduction into the machine, in particular a desiccation treatment. The machines must then be supplemented by desiccation equipment of the oven type or, as the case may be, by devices for diffusing inert or reducing gas onto the mixture of raw materials, which constitutes a significant constraint.

  The raw materials in the form of granules or powder (s) also have the drawback of having extensive contact with the walls of the mixing hoppers, which can pollute them.

  The present invention aims to remedy at least partially all or part of these disadvantages.

  For this purpose, the raw material to which it relates is formed by at least one elongate material capable of being fed continuously into the machine and to be fractionated and / or melted inside the machine.

  This elongated material eliminates the dispersion of the raw material at one or more feed hoppers or dosers, and eliminates the need to thoroughly clean this hopper or hoppers between each series of parts. This material also eliminates any contact, or at least an extended contact, of the raw material with the walls of a hopper, thus reducing the risk of pollution of this raw material by these walls.

  In case of change of raw material, especially in case of change of dye or additive, it suffices to interrupt the feed of elongated raw material at the end of the production of a series of parts and to feed the machine with the elongated raw material of the following series of pieces. The passage from one series of parts to another is thus made much simpler and faster than with a raw material, a dye or an additive according to the prior art.

  This elongated raw material also has a reduced contact surface with the ambient air, which reduces the need for prior treatment or the possible need for inert gas or reducing gas diffusion devices inside the machine.

  The raw material according to the invention also has the advantages of not spreading in a workshop and being able to be stored in a reduced volume, in particular by winding.

  The elongated shape of the material may be adopted either for the base material or a base material, for a dye, for an additive, or, according to a preferred version of the invention, for all the materials or products that the we want to introduce and mix in the transformation machine.

  Said elongate material may be in the form of one or more filaments, wires, cables, rods, strips, profiles or others. It can be full or hollow inside. It can group several materials intimately related or joined by junctions such as juxtapositions, welds or veils of material, braiding or ligatures.

  Said elongate material may in particular be in the form of one or more continuous son, of cross section may be between a few tenths of mm2 and a few tens of cm2, said son may be from one or more coils.

  In the case where it is hollow internally, the material may advantageously contain a particular atmosphere, for example an inert or reducing gas, or a vacuum, or dehumidified air, and / or may contain one or more other raw materials, in particular in the form of granules.

  This material thus allows, at the time of its splitting inside the machine, to diffuse the inert gas or reducing it contains, reducing or eliminating the need for devices for the diffusion of such a gas in the machine. This material also protects the other raw material or materials it contains from contact with the ambient air, and allows an intimate mixture of this or these other raw materials with the fractional portions of the material.

  According to another advantageous possibility, the elongated material according to the invention consists of a thin-walled continuous sheath, in particular of thermoplastic material, said sheath being filled with materials to be fed to the processing machine. This sheath preferably has a small wall thickness, for example 10 to 200 microns, and may have, for its inner hollow zone, a cross section of several mm 2 to several tens or even hundreds of cm 2.

  Said materials to be fed may be in the form of powder (s) or granules, or may themselves be elongated materials such as wire (s), braid (s), strips, etc.

  The sheath may consist of one or more materials which are identical or compatible with the feed material or materials which fill it, the assembly thus formed being then introduced globally, completely and continuously into the processing machine.

  An advantageous material according to the invention can for example be formed by a polyethylene sheath enclosing son, "cables", or granules themselves of polyethylene or compatible polyolefins (polypropylene copolymer for example) with or without dye (itself even on base compatible with polyethylene).

  In the less advantageous case where the sheath itself consists of a material incompatible with the materials it contains, for example in the case of a natural textile sheath or a polyolefin sheath (polyethylene or polypropylene) with a material to be fed styrenic type for example, the sheath can be opened, for example slit, to the right of the feed mouth of the processing machine, then recovered, for example continuously wound, and evacuated. The feed material is then introduced for example by gravity into the feed mouth of the processing machine, as soon as it escapes from the sheath.

  In any case, the sheath lined with the materials to be fed can be delivered to the transformer in the form of coils (similar for example to the coils of cables) or in the form of continuous "snakes" stored in containers of large capacities, for example a ton or more.

  The material or sheath, when it contains a gas or one or more other raw materials, may include zones of segmentation of its internal volume, arranged step by step. These segmentation zones make it possible to form independent pockets of gases or materials, and / or to maintain the one or more other raw materials inside the material or sheath, and / or to define a given quantity of this or these other raw materials per unit length of the material, and / or to make possible a winding of the material according to a limited radius, for the winding of this material. These segmentation zones can in particular be constituted by heat-sealing of the wall of the material or sheath.

  The elongated material according to the invention may also be in the form of a continuous cable consisting of filaments, continuous or not, twisted or not, this cable may or may not be included in a sheath itself consisting of one or more materials that are identical or compatible with the one or those constituting the cable.

  The invention also relates to a method for feeding a machine for converting thermoplastic or elastomeric materials into raw materials. This method comprises the steps of: - using a feed material of the machine, formed by at least one elongate material; - Feed this or these elongated materials continuously in the machine, and - split this or these elongated material at the feed mouth of the machine and / or melt this or these materials inside the machine.

  The fractionation may be carried out longitudinally, transversely or randomly, for example grinding or crushing.

  This method, when it does not concern all the components of the plastic material to be transformed, comprises the steps of: - using at least one component of the plastic material to be converted into the form of an elongated material, and - feeding this continuous component in the machine, at an adjustable feed rate, determined according to the speed of introduction of the other components of the plastic material and the ratio that must have this component with the other components of the plastic.

  The machine according to the invention comprises, in turn, at least one device for continuously feeding the raw material according to the invention, in particular one or more pairs of wheels, rollers or rollers driven in opposite directions, between which this raw material passes.

  The splitting of this raw material can, when the machine comprises a worm conveyor raw material, be made directly by the worm of the machine. The machine may comprise, if not a splitting device of the raw material, for example a device comprising one or more pairs of wheels, rollers or tooth rollers more or less sharp, meshing or not with each other, between which passes the raw material according to the invention.

  These drive devices of the raw material according to the invention can be controlled electrically or electronically for example, in coherence with the speed or the flow rate of the processing machine.

  This control can be slaved to the speed or flow rate of the processing machine to include particular compositions in percentage of the total material obtained at the output of the processing machine, including the percentage of dye (s). This percentage thus becomes easy to respect thanks to said control of the rotational speeds of rollers or gears, which makes it possible to reliably determine the speed of travel and introduction, for example of a thread consisting of "dye", that is, that is to say a concentration of pigments + dispersant products included in a polymer matrix compatible with the main material (s) to be colored and previously extruded in its wire form.

  When it is a dye or an additive shaped elongated material (wire or other continuous element) and in particular in the case of organic particles always more difficult to disperse than mineral particles, the material manufacturer first can usefully provide a higher percentage of dispersant (zinc stearate, talc or other product increasing the dispersion) so that the presentation of the dye or the additive as elongated material, instead of powder (s) or granulated (s), does not affect the quality of the final dispersion in the raw material (s) in the processing machine.

  The invention will be better understood, and other features and advantages thereof will appear, with reference to the appended schematic drawing, showing, by way of nonlimiting examples, an embodiment of the machine that it relates and several forms of realization of the raw material which it also concerns.

  Figure 2 is a side view, very simplified, of this machine, in longitudinal torque; Figures 3a to 3d are perspective views of portions of the raw material, in four embodiments, and Figure 4 is a side view of this raw material, according to one of these embodiments.

  FIG. 2 shows an extrusion machine 1 comprising the same members as those described with reference to FIG. 1, with the exception of the raw material 3 in the form of granules. The bodies that are found are designated by the same reference numerals and, being well known in themselves, are not particularly detailed.

  As shown in FIG. 2, the machine 1 is fed with an elongated raw material 10 fed continuously into the hopper 2 from a spool 11 by means of contra-rotating gear wheels 12.

  The raw material 10 passes over guide wheels 13 and passes between these gears 12, which are equipped with sharp teeth which fragment this raw material 10. The fragmented material 10 then falls into the tube 4 and is conveyed to the head 7 by the screw 5.

  This raw material 10 can adopt various shapes, four of which are illustrated in Figures 3a to 3d.

  It may be in the form of a monofilament or multi-wire material, as shown in FIGS. 3a and 3b, respectively. In this second case, each wire 15 is connected to the adjacent wire 15 by a web of material 16.

  Each wire 15 may be solid or hollow internally.

  The same wire 15 can group several materials, closely related to each other, or the different son 15 may be in different materials.

  The raw material 10 may also comprise a hollow sheath 17 containing one or more wires 15, as shown in FIG. 3c, or a thin-walled sheath 18 containing one or more materials 3 in the form of granules or powder, as shown in FIG. figure 3d.

  The material of the sheath 17 or 18 may or may not be compatible with the supply material or materials 15, 3 which fill it. When it is not compatible, the sheath 17 or 18 is open, for example slit, to the right of the feed mouth of the machine 1, then is recovered, for example continuously wound, and discharged.

  When hollow internally, or when it comprises a sheath 17 or 18, the raw material 10 may contain a particular atmosphere, for example an inert or reducing gas, or a vacuum, or dehumidified air. This raw material 10 then diffuses, at the time of its splitting inside the machine 1, the atmosphere it contains, reducing or eliminating the need for devices for diffusing such an atmosphere in the machine 1.

  FIG. 4 is a side view of the raw material 10 including the sheath 18. As shown, this sheath 18 comprises zones 20 of segmentation of its internal volume, arranged step by step, in particular by welding the walls of this sheath 18. These segmentation zones 20 make it possible to form independent pockets 21 of raw materials 3, ensuring the maintenance of these raw materials inside the sheath 18, making it possible to define a given quantity of these raw materials 3 per unit of length, and making possible a winding of the raw material 10 according to a limited radius, on the coil 11.

  As can be seen from the foregoing, the invention provides a feedstock for a thermoplastic or elastomeric processing machine having the following significant advantages: - to eliminate the dispersion of the raw material at the level of a hopper 2, and thereby eliminate the need to thoroughly clean this hopper 2 between each series of pieces; - to eliminate any contact, or any extended contact, of the raw material with the walls of a hopper, a weighing, mixing or dosing device; - to easily interrupt the supply of raw material at the end of the production of a series of parts and to easily feed the machine with the elongated raw material of the following series of parts; to have a reduced contact surface with the ambient air; - to be able to be stored under a reduced volume.

  It goes without saying that the invention is not limited to the embodiment described above by way of example but that it extends to all embodiments covered by the appended claims. In particular, if the section of the raw material 10 allows it, the fragmentation of this raw material can be carried out directly by the screw 5 at the lower opening of the hopper 2; the wheels 12 can then be simple driving rollers of the raw material 10.

Claims (16)

  1 raw material (10) for feeding a machine (1) for processing thermoplastic or elastomeric materials, in particular an extruder or an injection molding machine, characterized in that it is formed by at least one elongated material capable of be fed continuously into the machine (1) and be split at the machine feed mouth (1) and / or melted inside the machine (1).   2 Raw material (10) according to claim 1, characterized in that said elongated material is in the form of one or more continuous son (15), of cross section that can be between a few tenths of mm2 and a few tens of cm2, said wires (15) being able to come from one or more coils.   Raw material (10) according to claim 1, characterized in that said elongate material (17, 18) is hollow internally and in that it contains a particular atmosphere, for example an inert or reducing gas, or a vacuum, or dehumidified air, and / or in that it contains one or more other raw materials, especially in the form of granules.   4 raw material (10) according to one of claims 1 to 3, characterized in that it consists of a thin-walled continuous sheath (18), in particular of thermoplastic material, said sheath being filled with materials (3). ) to feed on the machine (1) of transformation.     Raw material (10) according to claim 4, characterized in that the sheath is made of one or more materials which are identical or compatible with the feed material or materials which fill it, which allows its simultaneous introduction into the machine (1 ) with the material or materials to be fed.   6 Raw material (10) according to claim 3, characterized in that the sheath is made of one or more materials not compatible with the one or more feedstocks.   7 raw material (10) according to one of claims 3 to 6, characterized in that said elongated material comprises zones (20) of segmentation of its internal volume, arranged step by step.   8 Raw material (10) according to claim 7, characterized in that the segmentation zones (20) consist of heat-sealing the wall of the material.   9 raw material (10) according to one of claims 1 to 8, characterized in that said elongated material includes several materials intimately related to each other or joined by junctions such as juxtapositions, welds or sails material, a braiding or ligatures.     Raw material (10) according to one of claims 1 to 9, characterized in that said elongate material is in the form of a continuous cable consisting of filaments, continuous or not, twisted or not, cable may or may not be included in a sheath itself made of material (x) identical (s) or compatible (s) with the constituent (s) of the cable.   11 Method for feeding a machine (1) for transforming thermoplastic or elastomeric materials, characterized in that it comprises the steps of: - using a raw material (10) for feeding the machine (1), formed by at least one elongated material according to one of claims 1 to 10; feeding said one or more elongated materials continuously into the machine (1), and fractionating longitudinally this or these elongated materials at the level of the feed mouth of the machine (1) and / or melting this or these materials to the inside the machine (1).   A method of feeding according to claim 11, comprising the steps of - using at least one component of the plastic material to be transformed into an elongate material, and feeding this component continuously into the machine (1), an adjustable introduction speed, determined according to the speed of introduction of the other components of the plastic material and the ratio that this component must have with the other components of the plastic material.   13 Machine (1) for converting plastics for implementing the method according to one of claims 11 or 12, characterized in that it comprises at least one device (12) for continuously feeding the material first (10).   Machine (1) according to claim 13, characterized in that it comprises one or more pairs of wheels (12), rollers or rollers driven in opposite directions, between which this raw material (10) passes.     Machine (1) according to claim 13 or claim 14, characterized in that it comprises at least one device (12) for fractionating the raw material (10).   Machine (1) according to claim 15, characterized in that at least one fractionating device of the raw material (10) comprises one or more pairs of wheels (12), rollers or tooth rollers more or less sharp, meshing or not with each other, between which passes the raw material (10).   Machine (1) according to one of claims 13 to 16 characterized in that it comprises a control device, preferably electric or electronic, the speed of introduction of the material or in elongated form.   Machine (1) according to claim 17, characterized in that the control is slaved to the speed or the speed of the machine (1) of transformation in particular to respect compositions in percentage of the total material obtained at the exit of the machine. machine (1) for processing.   Machine (1) according to one of claims 13 to 18, characterized in that it comprises a device for opening, for example slitting, a sheath that comprises the raw material (10) according to the invention, and a recovery device, for example continuous winding, and evacuation of this sheath.