DE1704979B2 - METHOD AND DEVICE FOR PRODUCING AN ELECTRICAL CONDUCTOR INSULATED WITH FOAMED PLASTIC - Google Patents

Description

The invention relates to a method of manufacture an electrical conductor insulated with foamed plastic, in which the conductor is connected to a viscous solution of a crystalline polymer with the help of an extrusion head and then coated the coated conductor for foaming the coating is heated.

The methods heretofore used have been to dissolve a polyolefin such as polyethylene in an organic solvent, draw this solution over the conductor, and then cool the coated conductor so that the crystals of the polyolefin are formed, followed by drying until the weight of the solvent was about 50% of its original weight, a ventilated electric furnace heated to about 350 to 400 ° C was run in order to melt the polyolefin and at the same time the remaining solvent in the interstices to evaporate the crystallized poryolefin particles, whereby closed cells were formed in the coating due to its pressure and the pressure of the air present in the interstices, ίο in investigations to improve electrical conductors and in efforts to produce further closed cells in the coating was found that the method used so far is the successor end has disadvantages

1. In a system in which the solution of the polyolefin between the reserve containers and the coating tank is circulated by means of a pump or pressure, as described in detail below, a

Part of the crystalline polymer in the line of the circulation system is always in solution and if the operation is continued for a long period of time, the remaining crystalline polymer can decompose through oxidation at higher temperatures (100 b ^; s 135 ° C), which leads to pinholes or leads to damage to the coating, so that a deterioration in the quality of the coating occurs. In addition, some of the solution is not removed when the inside of the circulatory system is cleaned and solidifies and the solidified polymer is again found in the solution during operation and results in pinholes and other damage.

2. When the coated Leitei is cooled and dried after solution coating, so that 50 remain to 60 ⁰ Zo solution Mitel in the coating, and it is heated in this state, it was found that the remaining solvent is not uniform in the coating of the coated conductor evaporates, causing eccentricity and voids in the coating and other imperfections in the electrical conductor.

The French patent specification 957 687 already discloses a process such as a device for coating an electrical conductor with an insulating coating made of a thermoplastic material, in which the thermoplastic material, in particular polyethylene, is pressed with a foaming agent through a screw into a nozzle opening, through which the electrical wire to be coated is drawn at the same time, which is transported d'irch the plow axis of the worm. After exiting the nozzle, the coated wire is then passed through a heating device which heats the coated wire to a temperature such that the foaming agent is foamed. However, such a method has the disadvantage that essentially all of the solvent formed by the foaming material remains in the foamed material.

The present invention is based on the object of an electrical insulation coating to apply electrical conductors that have improved electrical insulation properties.

ί 704 979

This task is achieved in a method which is that the heat transfer coefficient initially mentioned type of air flowing thereby according to the invention is about ten times as large as dissolves the solution in a dissolving tank, that of stagnant air, so that it becomes possible Pressurized in a container and increased by the heating temperature and duration a thickening device of a measuring gear pump or, in other words, the tub is guided so that the extrusion head has a constant capacity for heating and the length of the pipe To reduce the amount of solution by means of the measuring gear pump.

is required, and that the coating up to the case, as in Fig. 3, an electric heater33

removal of the solvent from the coating inside the tube 31 for keeping warm

is dried before the plastic is foamed. io det, the conductor becomes through the thermal radiation

This has the advantage that the insulation from the wall of the electric heater 33 is additionally

latioi! degrading pinholes in the insulation heated to the heating by the hot air, wherein

coating or the appearance of voids in which the hot air in this case has not cooled down in the pipe

insulation coating can be avoided. Furthermore, so that the heating temperature and heating

15 as an advantage of the method according to the invention, the duration can be further reduced,

found that, as spherical polyol particles, the preheated conductor is then

Geschinolzen after the solvent is fed into the press head 4, where a viscous solution of a

the coating has been virtually completely removed from crystalline polymers such as polyethylene, polypropylene

is, it is possible that in the interstices around pylene and the like pulled over the preheated conductor

the spherical polyolefin particles will be present. In the following, the 'precautionary head 4 is executed

Isolate gases, air and solvent vapor and portrayed them.

thereby to obtain a coating, the closed one crystalline polymer, for example poly cells having. It has been found that ethylene, polypropylene and the like are heated and combined this procedure becomes very easy to mix with a solvent such as xylene, toluene uniformly foamed insulation cover of high 25 and ugl. stirred in a dissolving tank 41 so that Establish insulation quality and at the same time result in a solution. This solution is used by the To improve the efficiency of the production, since here dissolving tank 41 is led to a container 42 and there stored with no evaporation of large amounts of solvent. This solution is done by a printing device. device 43 first conveyed to the measuring device pump 44

The invention also relates to a device. The solution is through the measuring gear pump device for carrying out the method for Hersiel to the extrusion head 4 with constant drainage gel one with foamed plastic insulated speed pressed out and electric over the conductor Head with an extrusion head and pulled.

a device for foaming the coating, if the solution is very viscous and not very liquid,

which is distinguished by a pressure device for 35, it cannot be applied to the metering gear pump 44

Feed the viscous compartment stored in a container. This is why the

Solution of a crystalline polymer is applied to a measuring pressure device 43 by one

gear pump through which the expressing head> f exerts a pressure on the solution when the

constant amount of the solution can be supplied and is supplied by metering gear pump 44. If the

one in the sequence of the work sequence before the 40 solution of the metering gear pump is completely

Device for foaming arranged frock- leads, the metering gear pump can be a con-

voltage device for the coating. Squeeze out a constant amount of the solution released by the

As a result, the number of revolutions of the transmission is advantageously independent of the number of revolutions the previously known devices a pressure equal to the pressure applied to the solution Composition of the solution and a 45 is correct. With regard to the more uniform for this purpose Application of the solution achieved. set printer 43, it is sufficient that the on Furthermore, at the same time, a large number of pressure applied to the solution can be sufficient to achieve the Wires are processed. In addition, the solution is used to supply the measuring gear pump. That's why direct application of the solution to a coating is not a very high level of accuracy with regard to the The tende.i wire prevents the solution from decomposing under pressure.

sets, so that damage to the coating by this As a cover device 43 can be a rotating

Decomposition products are prevented. Pressure device, for example a gear

In the following, the invention will be based on a prepump, a screw pump and dpi. or a com-

According to the embodiment of the production process, primed gas can be used. As shown in Fig. 4

rens and the device used in detail 55, it is possible with a printing device

to be discribed. the charging of the viscous solution to some measuring

According to FIG. 1 is the conductor, which from a drive pin 44 through a common tube 45

zkhstand 1 is fed through to effect the voltage. On the other hand is a measuring gear pump

controller 2 through which the voltage of the conductor is necessary for each individual extrusion head 4.

is precisely regulated. The Leiti then comes in. It is essential that the solution does not circulate

Conductor preheater 3, which is referred to below simply as. The solution of a crystalline poly-

Preheater is called. meren is only used in one direction

As shown in FIG. 2, the preheater is pressed out so that the total amount is within one built up so that the conductor is pressed out through a pipe31 which has been pressed out for a certain period of time. Therefore being kept warm and that heated air 32 in 65 would not be any part of the high temperature solution Tube 31 for heating the conduction ice is blown in and exposed for a long period of time, whose is the possibility of harming one

The benefit of using heated air crystalline polymers in the present novel

Coating process is significantly reduced. If it were intended, "would be the linear velocity therhin the interior of the pipe can be easily cleaned of the conductor passing through the extrusion head 4, when operation is interrupted. significantly by changing the elongation of the conductor

Up to now it has been constant practice that the solution in the be varied by giving it in the pre-collecting circuit was conducted. As a result there was some 5 directional tension caused by itself Parts of the solution that have high temperatures - if this voltage in itself is only low, because the long periods of time. There will be distance between the extrusion head and the reel z. For example, suppose that half of the solution would be very long even if kept constant Container is squeezed out and the rest could become the loading.

holder is returned. Da; to remain (Vi) "of the io The collecting device 9 can, for example, be of the type initial volume after η passes in these of the traveling rollers shown in FIG. 5, where this operation not squeezed. Theoretically, one remains the length of the collected coated conductor such a part infinitely long "in the system. In by the distance between the roller shafts 93 In this case, at least a portion of this remaining and 94 and the number of revolutions is determined borrowed part because he turns 15 during a long time. The rollers 91 and 92 are rotatable on the Exposed to high temperature for a period of time, roller shafts 93 and 94 are fastened with ball bearings, The roller shafts 93 and 94 are arranged vertically Cause of pinholes. net. The lower roller shaft 94 is fixed while

A metering gear pump is driven up and down the upper roller shaft 93 for operation Pressing out in one direction without circulatory 20 is possible. To work on the arrangement of the Leifführung used to obviate such disadvantages in order to make the roles easy, the avoid and by the outflow speed at the upper roller shaft 93 closer to the lower shaft to stabilize. The ladder over which they are lowered. If the facility is in operation Solution has been drawn up, goes through a device located, "'ird the upper roller shaft by means of a tung5 for cooling, namely water, which effectively pulled 25 torsion motor 95 to the desired is to reduce the vibration of the coated conductor. Collection length of the coated conductor and keep the haze appearance of the coating.

Accelerate τη, then runs through a water drain The tension given to the conductor at this point

removal device 6, in which the blowing in of air is effected by the rotation of the motor. takes place, and enters a drying device 7 30 It is therefore possible to give the head a desired to apply tension to the coated conductor when the hot air is blown to the motor will. The application of a water drainage voltage is regulated. In the above tion device 6 is used to prevent the one, the device was described so that only the bring water into the Tirockmmgsvorrichtung 7 upper roller shaft 93 is movable. To reduce and also to stabilize the turbidity time, the tension can, however, both the upper for the occurrence of the haze phenomenon is required as well as the lower shaft are driven or is. it can be some of the rollers on a shaft or on

The method for accelerating the turbidity two waves are driven,
Appearance by means of a trough with water and the conductor is in an electric wire insulated by a foam type of a drying device 7, in which hot air is usually blown from a substance, represents an already proposed smaller diameter between 0.32 and 0.4 mm . The process has other advantages in that it is prone to breakage or elongation, so far as there are seasonal changes that it is necessary to prevent the chip time that is required to reach the coated Conductor voltage exceeds a certain value. On the other hand, by a first guide roller after coating 4; i it is necessary, however, that a certain amount of it is wound up, brought to a minimum and that tension exceeding the fixed value is prevented during operation without causing unpleasant disturbances and other reasons will harmful vapor of the solvent in the working As a result, the area of allowable chip space enters. By blowing air on the voltage closely and changing the voltage, the coated conductors in the drying device must be kept to a minimum. In the collecting pre in a regulated amount of regulated temperature and direction 9, the rollers receive the revolving power. Moisture is cooled and the solution through the coated conductor and the greater the amount of turns from the coating to such an extent, the greater the number of turns Spannunj removes that the coating is not damaged and / or preserves the coated conductor. In this context, it is deformed when the coated conductor is around the 5!> Slope the rotation of the roller shafts an actual reel 8 runs around. After the conductor has passed the dangerous means to push the increase in voltage to below pel 8, he enters a collecting device 9 or to decrease the voltage. To remove the solvent from the coating, rollers are placed on the roller shafts with one in between. A reel 8 is attached to the ball bearings in front of the collecting device 9, the friction between; provided for the purpose that the linear speed transmits the rotational force from the shafts to the speed of the Lei rolls running through the extrusion head 4. The appropriate number of orderers is kept constant. rotation of the shaft is equal to or around 10 ° /

As already stated, the solution with con is greater than the number of revolutions of the roller constant outflow velocity. One that corresponds to the linear speed of the conductor Change in the linear speed of the 65 chen. However, even if the number of revolutions Extrusion head 4 running conductor would therefore be a gene smaller than the number of turns de Change in the thickness of the coating. Roles, this is effective in reducing the Ai

If the reel 8 after the collecting device 9 increased the tension.

-W \ 2757

° ^l0 I ⁵ n ^k d ^P ef illustration of the F ig 5 ^ J roller shaft shown as being rotatable.It is J ^ed ° ^c _R & _ Hch to rotate both the upper and the lower roller shaft. duration ie the

the receiving device 13 by using the ^^ _movable rollers of the collecting device 9

To regulate traveling roles.

. _{Iaich this} collecting device 9 the _{at the time kt> in de} ; n the head S ^ ^ _wescntIlCh improved,

^ _{RoHenwdle {is} made cantilevered, like

ⁱⁿ Si ^ sLteSlchtung 9, which _{was changed} above geschil _is of a vertical arrangement, wherein a ^ ^^^ _{mounted verükal.} A collecting device of the horizontal type is also possible, the one listed above

_{and the} collection new

^l _"tung 9 to combine, as in g F i. 7 marked. This is _{advantageous if} a collection and _drying device of the hrizontal type is used for this purpose

Handling of a ladder is used.

^ " _Berz ^. ^^ _its solvent in

its coating ng during his stay in the _Sammeleinric h _tU was removed, enters the shop _mungse inrichtung. As such Schaumungsein- ^ ^ _n ^ _{bekanntef electric} oven comparable

Fl

SaSmlunÄfw ^ d j
the Saininel device 9

temperature above room temperature g

up to 80 ° C to accelerate the Veriamp g

remaining solvent in the coating

will blow. , _{R di before the}

The speed of the reel J * _e ^ w «

Collection device is located, ™? ^ Ε ^^ acquisition device 13 are chronized as the last stage. However, it is very ^

Complete Synchroniser ^^, the ^ g ^ ^ _n ^ _{knownef electric}

speeds this Emnchtung because ug _wendgt ^ _{yet. $ {} ^ a liquid

inaccuracies in the manufacture of WUten una _keitssch äumungstrog 10, for example with glycerol,

to use ^^ Sites of which rhitzungswirksamkut to an electric fhchwmdigterten α ^ _{hinsichtHch E} and temperature - other reasons to ^^ "

_raturre g _e i _U ng is far superior. The coated, "conductor guided through this Schäumungstrog 10 - _{is the ABG is} espült and cooled in the tin _rich tung 11, wherein he first with warm water" on 40 ° C or above one or more stages

inaccuracies

other reasons ^^ '- ^^ Sites of terschied in the α Aufnahmegeschwmdigterten two devices is very low, rst sammeu ^, this small difference ^ ~ ^ ^{3η ηα} 3 eiuaün during a long ^ "b which are immediately prior to the hiking tung 13 ^ rollers. ? ^ α.

_Is to regulate collecting device 9 and thus the cost sc ^ ^^ _{water yerwendet>} ^^ _thereby verruigern the equipment. immediately the length of the sink trough is reduced very much because it

coated LaBi. KonsM the area of the to the SctaMnen

_geoomm en after α has gone through 12, if necessary, in order to measure the electrical properties of the conductor.

For this purpose 2 sheets of drawings

209 550 /

* <■■■ «ν-

27

Claims (3)

I 704 979 patent claims: 1. A process for the production of an electrical conductor insulated with foamed plastic, in which the conductor is coated with a viscous solution of a crystalline polymer with the aid of an extrusion head and then the conductor is heated over iogene to foam the coating, characterized in that the solution in one is set dissolving tank gerunff} in a container under pressure and fed through a Drückeinrichtiiäg eirier Meßgetriebepuiupe that the Auspreßkopf a constant amount of the solution is conveyed by means of the Meßgetriebepumpe, and that the coating to zw removal of the solvent from the coating is dried, before the plastic is foamed. 2. Device for the production of mi * foamed plastic insulated electrical conductors according to claim 1 with an extrusion head and a device for foaming the Coating characterized by a pressure device (43) for feeding the in a container (42) stored viscous solution of a crystalline polymer to a measuring gear pump (44), through which a constant amount of the solution is fed to the press head (4), and through a arranged in the order of the work flow before the device for foaming Drying device (7) for the coating. 3. Apparatus according to claim 2, characterized in that in the sequence of the work flow after the extrusion head a device (5) for cooling the coating with water, a drying device (7) with a tub air flow for the cooled coating, a collecting device (9) for removing the solvent from the cover and one between the drying device (7) and the collecting device (9) horizontal reel (8) are provided.