JPS61179717A - Extrusion method for manufacturing needle coated with foamedplastic and device used for said method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an extrusion method for producing foamed plastic-coated wire, the apparatus used, the produced wire, and methods of using the wire. More specifically, plastic melts consisting primarily of thermoplastic resins, chemical or physical foams and optionally pigments.

The present invention relates to an extrusion method for producing a wire covered with foamed plastic, which consists of extrusion with the wire being continuously fed into an extrusion tool, the apparatus used, the wire produced, and the method of using the wire.

A wire insulated with a foamed plastic material is known from DE-O 51515805. A disadvantage of this foamed plastic-coated wire is that the adhesion of the foam casing to the wire is unsatisfactory.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a foamed plastic covered wire in which a foamed plastic casing tightly encloses the wire.

This object is achieved according to the invention by using a wire that is cooled below room temperature, preferably below 0°C.

In the production of such a wire with a foamed plastic casing according to the invention, the extrusion tool has an extrusion tool which projects into the extrusion tool without contact with the extrusion tool and which has a large wire feed channel. A wire feed device (3) surrounding the section is fitted, the wire feed channel protruding unsupported from the outlet of the wire feed device into the mantle point, and further the wire feed channel is surrounded within the wire feed device by a cooling chamber. A device is used which is characterized in that the wire, which has already been cooled in a cooling device and is fed therein, remains cold until it comes into contact with the plastic melt.

According to the invention, therefore, a foamed plastic consisting of extruding a plastic melt consisting mainly of a thermoplastic resin, a chemical or physical foaming material and optionally a pigment together with a wire that is continuously fed into an extrusion tool Provided is an extrusion method for producing a wire covered with foamed plastic, characterized in that the wire is used in a state cooled to below room temperature.

The present invention includes the above-mentioned apparatus for carrying out the method of the present invention, and the products, namely a wire coated with a foamed plastic, and a wire coated with the foamed material, which can be used to cut stems, trunks, branches, limbs, etc. It also includes a method of use for tying up parts of plants. Furthermore, according to the invention it is also possible to produce electrical conductors insulated with a foamed plastic casing.

The invention will now be further described in conjunction with FIGS. 1 and 2. 1 and 2 show a preferred embodiment and are intended to illustrate the following description.

As shown in FIG. 1, the wire feeding device 3 is attached to the flange of the extrusion tool 2. A spacer 9 (preferably made of a heat insulating material) is provided between the wire feeding device 3 and the extruding tool 2 so that the portion of the wire feeding device 3 protruding into the extruding tool 2 does not come into contact with the extruding tool 2. It is located.

Therefore, the gap between the extrusion tool 2 and the wire feeding device 3 also serves as a heat insulator.

A wire feed channel 4 located in the wire feed device 3 is surrounded by a cooling chamber 7 . A cooling liquid flows through this cooling chamber, which cools not only a large part of the wire feeding channel but also the wire feeding device [i! The portion of 23 protruding into the extrusion tool is also cooled by conduction. By this method, the wire, which has already been cooled before entering the wire feeding device 3, can be passed through the mandrel opening 8 while maintaining its temperature.
and comes into contact with the hot plastic melt in the die chamber 12. This cools the plastic melt in contact with the wire and forms a thin layer on the wire, tightly enclosing it. This layer is formed on the wire by cooling, on the other hand, in order to prevent reheating or melting of the plastic layer formed on the wire during cooling.

It is important that the distance between the mandrel opening 8 and the die orifice 11 be appropriate to the working conditions, such as the wire delivery speed and the temperature conditions of the melt at that time.

Most of the cooling performed on the wire is performed before it enters the wire feeding device 3, as described above. This cooling can be performed by the method shown in FIG. That is, the wire is continuously drawn out from the wire winding drum 16, passed through the wire centering device 15, and then passed through the cooling device 14. From the cooling device 14 the wire is preferably led directly into the wire feed device 3 without contact with the outside air.

However, the entire wire drum is cooled in a suitable deep-freezing cabinet or deep-freezing box, from which the wire is passed through a special take-off device, preferably under vacuum and optionally cooled. Of course, it is also possible for the wire to be guided into the wire centering device 15, which is currently being used, and from there directly into the wire feed device 3.

It is therefore clear that the essential feature of the method of the invention is the use of a cooled wire. Because the wire is cooled (preferably intensely cooled), the plastic melt to be foamed in the die, i.e. in the die chamber 12, cools and precipitates as an unfoamed thin layer on the wire;
This forms the bond between the wire and the foam. If uncooled wire is used, the foam casing will not adhere firmly to the wire. In this case, there is even some play between the wire and the foam casing, allowing the wire to be easily moved back and forth.

In order to obtain the desired thickness of the foam casing, a specific die orifice to wire diameter ratio must be selected. This ratio is preferably 2.5=1. In a preferred embodiment of the invention, this ratio is 2.5:1, which results in a foam casing diameter of 10 mm for a wire diameter of 1 mm. Of course, the diameter of the foam casing also depends on the composition of the plastic melt to be foamed.

Generally, a casing is made from a single foamed plastic by an extrusion method using a screw extruder.

As a general rule, azodicarbonamide and 4,4'-oxybis(benzenesulfonyl hydrazide) are used as chemical blowing agents, and inert gases such as nitrogen, argon, carbon dioxide, or methane, propane are used as physical blowing agents. , butane, pentane and hexane, or gaseous or liquefied fluorohydrocarbons such as trichloromonofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane and dichlorotetrafluoroethane. Generally, plastics are polyolefins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, and butyl rubber, or mixtures of two or more of these materials. The most frequently used plastic materials are polyethylene and polypropylene.

According to a preferred embodiment of the invention, 60 kg/am”
In order to obtain a rough surface of the plastic casing with a foaming density of less than 1:2 and a ratio of wire diameter to plastic casing diameter of at least 1:8.

(a) A physical blowing agent in an amount of 20-30% of the thermoplastic resin is added directly to the melt in the extruder.

(b) Low-density high-pressure polyethylene is used as the thermoplastic resin.

(c) the temperature of the mixture to be foamed is between 60 and 105°C as it exits the extrusion die together with the wire; (d) the discharge speed is at least 50 m/min; and (e) the wire is of quality class DIN. (German Industrial Standard) 17140
A soft iron wire whose temperature has been cooled to 10°C is used.

Of course, in the method of the invention, the adhesive may be applied to the cooled wire in the form of a very thin covering before it is fed into the plastic melt.

This method may further improve the adhesion of the foamed plastic casing to the wire. But generally this is not necessary.

In the preferred embodiment described above, the distance between the mandrel opening 8 and the die orifice 11 is preferably 18.5
cm.

[Brief explanation of drawings]

FIG. 1 shows a cross section of an extrusion tool with a wire feeder attached to the flange. FIG. 2 shows a schematic diagram of the entire device according to the invention. The meanings of reference numbers in the figures are as follows. 1, extruder 2, extrusion tool 3, wire feeding device 4, wire feeding channel 5, outlet 6 of wire feeding device (3), mandrel point 7, cooling chamber 8, mandrel opening 9, spacer 10, extrusion die 11, Die orifice 12, die chamber 13, plastic melt conveying section 14, cooling device 15, wire alignment device 16, wire winding drum Patent Applicant: Nonyl, Martén C. Varnish, ah.

Claims (1)

[Claims] 1. A wire covered with a foamed plastic made by extruding a plastic melt mainly made of thermoplastic resin, chemical or physical foaming material together with the wire that is continuously fed into an extrusion tool. 1. An extrusion method for producing a foamed plastic-coated wire, characterized in that the wire is used in a state cooled to below room temperature. 2. The foam density is less than 60 kg/cm^3 and the ratio of wire diameter to plastic casing diameter is at least 1.
In order to obtain a rough surface of the plastic casing such that: (a) a physical blowing agent in an amount of 20-30% of the thermoplastic resin is added directly to the melt in the extruder, (b) a low density (c) the temperature of the mixture to be foamed is between 60 and 105°C as it emerges from the extrusion die together with the wire; (d) the discharge speed is at least 50 m/min; (e) The wire has quality class DIN (German Industrial Standard) 17.
The method according to claim 1, characterized in that a soft iron wire of No. 140 is used which has been cooled to a temperature of 10°C. 3. The method according to any one of claims 1 and 2, characterized in that the cooled wire is coated with an adhesive and then fed into an extrusion tool. 4. The extrusion tool (2) is fitted with a wire feeding device (3) that protrudes into the extrusion tool (2) without contacting the extrusion tool and surrounds most of the wire feeding channel (4), and the wire The feeding channel (4) is connected to the wire feeding device (
3) protrudes unsupported into the mandrel point (6) from the outlet (5) of the wire feed channel (
The extrusion tool (4) is surrounded by a cooling chamber (7) in the wire feeding device (3), so that the wire that has already been cooled in the cooling device (14) and is sent comes into contact with the plastic melt. 2) Apparatus for carrying out the method according to any one of claims 1 to 3, characterized in that it maintains coldness within the apparatus. 5. The device according to claim 4, characterized in that a heat insulating material (9) is arranged in the flange portion between the wire feeding device (3) and the extrusion tool (2). 6. Separating the mandrel opening (8) provided in the mandrel point (6) from the die orifice (11) so that on the one hand a homogeneous cooling layer is formed on the wire and on the other hand this layer does not melt once formed. 6. Device according to claim 4, characterized in that the mandrel is arranged in the extrusion tool (2) in a similar manner. 7. Claim 4, characterized in that the ratio of the diameter of the die orifice (11) to the diameter of the wire is 2.5:1.
6. The device according to any one of paragraphs 6 to 6. 8. Claims 4 to 7, characterized in that an independent cooling device (14) is provided before the extrusion tool (2) for continuous cooling of the wire coated with foam material. The device described in any of the above. 9. A wire coated with a foam material manufactured by the method according to any one of claims 1 to 3 above. 10. A method of using the wire covered with the foamed material according to claim 9 to tie up various parts of plants such as stems, trunks, branches, and boughs.