DE1640144A1 - Double insulated telephone wire - Google Patents

Description

Double-insulated telephone wire The invention relates to electrical Cables, in particular cables for telephone and telecommunication purposes.

One of the difficulties in telephone networks was that # overland or. Outside cables not directly inside the building to the distribution frame in the central and local telephone exchanges, as the external insulation of the cable Was not sufficiently fire resistant for use inside the building. She suited not calibrated for what is often required for installations in limited space Bending and the resulting sharp kinks. The conductor insulation for its part was not resistant enough to exposure and mechanical handling that when removing the cable sheathing and fanning out the lines on the main distributor through perforated plates with end loops.

There have been improved communication cables for telephone systems with a Combination of electrical and mechanical properties developed by them Suitable as an outside cable as well as an end cable. It is no longer necessary use special end cables to cut the circles of incoming telephone cables at a central or local telephone exchange from the cable duct to the main distribution board to extend. This creates a splice in the cable duct along with the one that has to be used for it Avoided costs.

The invention relates to further improvements in communications cables of the specified type, namely an external insulating layer with the necessary electrical and mechanical properties proposed from different Strips of different color made one to one a color coding for to deliver the cable. As a result, the color coding is the pole of a compound The structure of the outer insulator layer is otherwise due to this invention special color coding step required in cable manufacture unnecessary.

The invention further aims at an economical process for Production of the improved telecommunication cable according to the invention with color coding.

Further properties and advantages of the invention emerge from the following description.

In the attached drawing, the same parts are in each case with the same Provided with reference numerals. Otherwise: FIG. 1 is a partial view with parts cut away to show the construction of a telephone cord according to the invention; Fig. 2 a Section along the line 2-2 of FIG. 1; Fig. 3 is a schematic drawing for explanation a method of making the cable shown in Figures 1 and 2; Fig. 4 and 5 schematic Da @@ positions on one @@ the following So @@ itte a modified one Method for producing the Kahel shown in Figures 1 and 2; Fig. 6 is a schematic Section of a part of the table in the spiral extrusion machine shown in FIGS. 3 and 5, , @ Fig. 7 is an enlarged section length of the line 7 7 of FIG. 6.

1 and 2 show an insulated line 10 with a lead wire 12, which is preferably made of copper. The lead wire 12 kazin with tin or be coated or plated with another metal, but will always be as follows referred to as "bare wire", regardless of whether it is over the copper wire a metal coating is located.

Immediately on the lead wire 12 is a first insulating layer 14 applied. This first insulating layer 14 consists of a plastic insulating material with good insulation properties and can be adhered to according to their electrical insulation properties be chosen without regard to their mechanical strength or fire resistance, as they tone a second and outer insulating layer 16 that overlies the first insulating layer 14 is squeezed in a manner explained below, is protected.

The insulating layer 14 is preferably made of a polyolefin.

In the preferred construction, the insulation layer 14 is polyethylene.

This material is unsatisfactory as an exterior insulation because it borrows burns and fiery. Material drips off, what an extreme indoor cable undesirable property it. This isolation is also the case for the desired one Capacity required Wall thickness for an outer layer is not sufficiently resistant and becomes excessive when soldering due to the effect of heat badly damaged. For an inner insulation layer, however, it is because of its low level Dielectric constant very useful.

The actual thickness of the first insulation layer 14 depends on the front Caliber of the lead wire 12, but is between half and two-thirds the radial thickness of the combined insulation layers 14 and 16. For ordinary A radial thickness of 0.25 mm is sufficient for telephone cables. The first layer 14 can consist of either solid or foamed material. Preferably a Low density, high molecular weight polyethylene is used, such as that of manufactured by Union Carbide under the name "DFDA-6033" and in the Trade brought product. Instead of this special polyethylene, a polyethylene can be used Use high density, polypropylene or copolymers of polyolefins.

The second insulation layer 16 consists of a mechanical and against Abrasion resistant material than the first layer 14; further is the second Insulation layer 16 also more fire-resistant.

For the second insulation layer 16, polyvinyl chloride is used as the material preferred, and this polyvinyl chloride is used in less than the usual amount Plasticizers compounded to create "semi-rigid" insulation. The expression "Semi-rigid" is used here to denote a material you are testing is approximately 70 "C" to 90 "C" on the durometer hardness scale.

This semi-rigid polyvinyl chloride has a higher tensile strength as a vsrgleichber @@ @@@@ th @@@ sit @@@ beren Meich @@ cher salary. That is an important one Distribute @@ you se the outer insulation becomes tougher, also the lower @ white @@@@ is salable in the outer layer is important in that it avoids the fact that the inner Insulation layer 14 with regard to its electrical properties when pressed on of the hot polyvinyl chloride @ is deteriorated over the polyethylene. I'm another one The advantage of the reduced plasticizer content is that the outer insulation layer 16 has a higher compressive strength.

Common polyvinyl chloride insulation material holds approximately 60 parts Plasticizer per 100 parts of polyvinyl chloride resin. The "semi-rigid" used according to the invention Insulation 16 contains 20 to 30 parts plasticizer per 100 parts resin. Refer to parts focus on weight here. Such a reduction in the amount of plasticizer increases the Tensile strength of the polyvinyl chloride from about 158 kg / cm2 to about 259 kg / cm2 or about that. These values are given for illustrative purposes only.

The low plasticizer content of the polyvinyl chloride compound prevents any contamination of the underlying polyethylene insulation through walling of the Plasticizer.

The higher viscosity and the greater flow resistance due to the extrusion machine causes gradual decomposition of those used for the external insulation layer semi-rigid masses when a crosshead extrusion machine is used. the Has experience @@@@@@@ da # @ @h use of his spraying machine is described with L @ rgaspritc @@@@@@@@@@@@ in the USA patent 2 674 007, @@ @@@@ @@ @@@@@@@@@ With a low plasticizer content, the underlying layer of polyethylene is used @@@@@@ @@@@@ @@@@@@ lich is damaged. Such a str @@@ pr @@@@@@@ chine @@@@@ ttet the simultaneous pressing of 2, @@@ 4 who @@@ dedsmen basic colors and enables a total number of mohr els 200 different color codes.

The preferred soft mechar for the insulation layer 16 is di-2-ethylhexyl phthalate (electrical quality). Examples of other plasticizers that can be used are di-2-ethylhexyl adipate, Tricresyl phosphate and dicyclohexyl phthalate. . Small amounts of other substances, such as Stabilizers can be added to the polyvinyl chloride as usual.

Polyvinyl chloride can be either suspension or emulsion polyvinyl chloride be. Instead of polyvinyl chloride, other plastics such as copolymers can be used Vinyl acetate and vinylidene chloride can be used.

Although the polyvinyl chloride insulation directly on the bare conductor wire This type of insulation is insufficient because you use polyvinyl chloride a. Dielectric constant of 4 or more and for a telephone cord the desired alternating capacitance of 0.083 µF per 1.609 ki only with thicker Isolation and correspondingly large and expensive cables would be effective.

The electrical properties of Polyviny @@ loridma @@ en as electrical Insulators are inferior to those of polyolefins such as polyethylene.

The isolation 16 has a composite on @@@ zud bestek a plurality of different tapes 21, 22 and 23 which extend over the first insulation layer 14 are expressed spirally. Each of the members 21, 22 and 23 has one of the other Ribbons of different colors so that the composite outer layer 16 can be color-coded the insulated conductor 10 offers. The various bands 21, 22 and 23 become like this etrranged because they are close together and consecutive turns different tapes touch each other, so that # the insulation 16 is continuous. The bands 21, 22 and 23 are at a temperature of approximately 190-205 ° 0 applied so that egg. along their touching surfaces associate. The insulation layer 16 thus forms a coherent piece. One and only The difference between the tapes are the ones added to achieve it Pigments.

Figure 3 is a schematic illustration of a method of manufacture of the insulated conductors of Figs. 1 and 2. The bare lead wire 12 is from a Wire pile 26 unwound and guided through a conventional cross-head machine 28, which applies a plastic encapsulation to the bare wire. This plastic bag is the first insulation layer 14. Some distance behind the extrusion machine 28 runs with the leader its first insulation layer 14 through a second strand pre # machine 30. This extruder 30 is a spiral extrusion press and has a molded mouthpiece that rotates during the extrusion process, from which a A plurality of tapes 21, 22 and 23 (Fig.1) are pressed out to form the second insulation layer 16 to form.

The spiral extrusion machine 30 (Fig. 3) can according to the USA patent 2 674 007.

The Pig. FIGS. 6 and 7 show the construction of the molded tip part of FIG Extrusion machine 30. The conductor wire 12 with its first insulation layer 14 is fed through a guide 34 of a circumferential molding 36. That The molded mouthpiece shown has three channels 38 through which the plastic passes longitudinally titer 12 is squeezed out. Each of the channels 38 is fed by a different hopper supplied with molten plastic under pressure, so that it is a different one colored tape is pressed out over the first insulation layer 14.

The speed of longitudinal movement of the conductor 12 and its insulation layer 14 is matched to the speed of rotation of the molded mouthpiece @ 36 in order to au the various channels or nozzles 3B to get coils of plastic that each other b @@ ühren to form a continuous outer insulation layer 16, as explained above. On the molded mouthpiece 30 heating devices 40 are provided to the Maintain temperature of the plastic until the different tapes actually work on the first layer of insulation 14 have been expressed, whereby Successive turns of the plastic strips touch each other.

Again from Fig. 3 it is evident that the conductor with the outer insulation layer 16 continues a sufficient distance to allow the plastic insulation 16 to harden to enable, and the finished insulated conductor wound onto a take-up reel 42 will.

The type of extrusion head shown in FIG. 6, in which the channels 38 the plastic on the continuous conductor in one direction substantially delivering in the same direction as the conductor runs, has significant advantages Use of a "semi-rigid" external insulation layer. Such isolation with Their reduced plasticizer content does not flow easily and has considerable Disadvantages in extrusion machines Bit sharp curves to change the flow direction of the plastic near the dispensing end of the channels for the plastic. A "straight line" Screw extrusion machine of the type explained in FIGS. 6 and 7 is therefore for Applying the second insulation layer according to the invention is preferred.

Because of the different speed at which the first layer of insulation ii Compare bits of the composite second insulation layer bit their different Ribbons can be applied offers an application of that illustrated in FIGS Procedural advantages. These figures show a two-step process, whereby the conductor 12 unwound from a wire reel 26 and through the extrusion machine 28 at as high a speed as that required for unraveling the polyethylene or of the other first insulation layer 14 on the bare conductor wire 12 act can be used. Beyond the extrusion machine 28, the ladder runs far G @ enough to cool the plastic insulation 14, and is then on a take-up reel 46 wound.

This reel 46 is then used as a dispensing reel9 to To feed the conductor with its insulation layer 14 to the spiral extrusion machine 30, which in the same way as described above, the second insulation layer 16 on the ladder brings up, and after walking a long enough distance to the Cooling insulation layer 16, the finished insulated conductor is on the take-up reel 42 wound.

As usual, the insulated conductors according to the invention become cables unites and supplies a telephone cord with wider scope and a through the entire outer insulation layer.

To illustrate, there are two recipes of polyvinyl chloride for the Outer Isolatinsschicht indicated: Example 1 Polyvinyl chloride resin 100 parts of di-2-ethylhexyl phthalate 23.46 parts of D @ sibasic lead sulfate 3.70 parts of cadmium barium stabilizer 1.85 Parts of barium stearate 0.74 parts cadmium stearate 0.49 parts example 2 Polyvinyl chloride resin 100 parts Tricresyl phosphate 30.0 parts Dibasic lead phthalate Surface coated 10.0 parts Dibasic lead stearate 0.5 parts

Claims (1)

Claims i) Insulated titre for telephone and other communication cables, characterized by a first one which is applied to an electrical conductor (12) electrically insulating layer (14) made of a polyolefin and an outer one with color coding give away electrically insulating layer (16) made of polyvinyl chloride, which au .in.r Multiple different colored, spirally applied over the first layer Ribbons (21,22,23) consists, with successive turns of the different Spirals touch each other and form a continuous outer insulation layer. 2.) Insulated conductor according to claim 1, characterized in that the various spiral bands fused to form a continuous outer layer and these are made of semi-rigid polyvinyl chloride, one with the material of the first insulation layer contains compatible plasticizer. 3.) Insulated conductor according to claim 2, characterized in that the outer insulation layer on 100 parts of polyvinyl chloride resin about 20 to 25 Parts contains plasticizers. 4.) Insulated conductor according to claim 3, characterized in that a quality of di-2-ethylhexyl phthalate suitable for electrical purposes as a plasticizer, Di-2-ethylhexyl adipate, trioresyl phosphate or dicyclohexyl phthalate is used. 5.) Insulated conductor according to claim 4, characterized in that the outer insulation layer has the following composition: Polyvinyl chloride resins 100 parts of di-2-ethylhexyl phthalate 23.46 "tribasic lead sulfate 3.70" cadmium-barium stabilizer 1.85 "barium tearate 0.74" cadmium stearate 0.49 "6.) Method of manufacture an isolated loiter for electric 8 <', Fernm1dezweke, dai £ rcL-LC; .är QC D.cöwMtr Conductive wire by extrusion with a deste @ elektri @@@ @@ eluting layer Unsheathed from a synthetic material with good electrical insulation properties becomes and s @@@ a second layer on top of the first electrically insulating layer made of tougher plastic with poorer electrical insulation properties Extrusion in the form of a series of different ribbons made of differently colored Plastic, each wrapped in a spiral around the first insulation layer because # successive turns of the various spirals in the longitudinal direction of the conductor are close to one another and keep to one another, creating a continuous insulation layer b, we applied: 7.) Method according to claim 6, characterized in that that the second insulation layer from the various tapes in the heated state and welding the successive turns together for manufacture a continuous second insulating layer is applied. 8.) The method according to claim 6, characterized in that the first Insulation layer and the entire circumference of the conductor wire at a first point along the length of the line wire and the second, spiral built-up insulation layer around the head in a different location along the passage of the conductor and during this its passage from the first St @@@ @ @@@ @@@@@@@, is sprayed on. 9. experience @ according to claim 6, characterized in that # the eret @ @@@@@ tion @@ chi @@@ @m the ge @@ t @ n scope of the line wire to @@ er position ling @ @@@ Längedur @@@@@@ of the line wire up @@@@ tst, which insulates 1 'ans @@@ is @@@@ from this nasal @@@@ ogen and at a different speed than @@@ throughput speed pulled off the reel by the first point and a second take-up reel is supplied, the spiral-shaped insulating hand over the first insulating layer sprinkled on while the conductor runs from the first to the second reel. 10. @ The method according to claim 6, characterized in that # as a spiral Tapes have a polyvinyl gasket compound with a plasticizer content not exceeding about 30 Parts per 100 parts by weight of polyvinyl chloride using a straight pass set up spraying machine (with longitudinal spray head) is sprayed, the The rigidity of the polyvinyl chloride compound is compensated for by the fact that »the plastic straps essentially in the direction of passage of the conductor, but at the same time relative Rotation of the injection openings and the insulated conductor iit one on the longitudinal feed the conductor's coordinated speed squeezes out, so as to avoid the contact of the successive Get turns of the spiral ribbons together. 11.) The method according to claim 10, characterized in that ke @@@ eichnet, since # the Polyvinylchlori @@@@@@ he @@ rmt, with the @@@ dre bein spraying in B @@@@@@ ung @@@ the first insulation layer @@@ nom and the @@@@ vinylchlorid @@ ssoe at a temperai @@ @@@ chen about @@@ 190 injected up to 205 ° @ over a cooled first insulation layer made of polyethylene will. L e r s e i t e