JP2008506996A - Optical cable and method for making optical cable - Google Patents

Abstract

  The optical cable (1) has one cable sheath (11) and a plurality of optical transmission elements (101, 102) arranged in the cable sheath (11). Each transmission element has a plurality of optical waveguides (10101, 10102) and one strand jacket (1011) surrounding the optical waveguides (10101, 10102). The strand jacket (1011) has a matrix material and a filler embedded in the matrix material. The melting point of the matrix material is over 85 ° C. and the mass proportion of filler in the strand jacket is at least 30%.

Description

  The present invention relates to an optical cable having an optical transmission element with a strand jacket having a low elongation at break. The invention further relates to a method of making an optical cable which makes it possible to heat the optical transmission element to a temperature above 85 ° C.

  An optical cable has a plurality of optical transmission elements, also called “strands” or “units”. The optical cable further includes a cable core and a cable sheath surrounding the cable core. A plurality of optical transmission elements are arranged in the cable core. The cable sheath of the optical cable serves to protect the optical transmission element as well as to reduce the load. Suitable materials for the cable sheath have a high melting point. Known materials for cable sheaths include, for example, polyamide (PA), polyethylene (PE) or polyvinyl chloride (PVC).

  The optical cable can have 12 optical transmission elements. The optical transmission element can be color-coded with 12 distinct colors. Based on the color coding of the optical transmission element, the ends of the optical transmission element exposed at both ends of the cable strip are clearly distinguished from each other.

  The optical transmission element has a plurality of optical waveguides and one strand jacket surrounding the plurality of optical waveguides. The strand jacket of the optical transmission element makes it possible to classify the plurality of optical waveguides contained in the optical cable into distinguishable groups. The strand jacket should be able to be removed without special tools so that the light guide can be exposed easily and quickly. A suitable material for the strand jacket should therefore be soft. In particular, this material should have a low tensile strength and a low row elongation. Known materials for such soft strand jackets of optical transmission elements are, for example, chalk filled polyvinyl chloride or highly filled ethyl vinyl acetate.

  For example, an optical transmission element can have 12 optical waveguides. The optical waveguide can be color-coded by 12 distinct colors. Based on the color coding of the light guide, the ends of the light guide exposed at both ends of the section of the bundled strand are clearly distinguished from each other.

  The optical waveguide has a fiber coating (coating) and glass fibers surrounded by the fiber coating. In general, the optical waveguide is color-coded according to the color of the fiber coating.

  The 144 optical waveguides included in one optical cable can be classified into, for example, 12 groups each consisting of 12 optical waveguides. In particular, the twelve optical transmission elements of one optical cable and the twelve optical waveguides of one optical transmission element are color-coded using the same 12 distinct colors. Can be. For example, the strand jacket of an optical transmission element is color-coded by one of 12 colors, and the fiber coating of the optical waveguide of this optical transmission element is color-coded by one of 12 colors. be able to. In this case, both ends of one of the 144 optical waveguides included in the optical cable are connected to the fiber coating color of the optical waveguide and the optical transmission element to which the optical waveguide belongs. They are distinguished from each other based on the color of the strand jacket.

  The optical transmission element is arranged in the cable sheath so that the section of the optical transmission element with a certain length extends within the section of the optical cable with a certain length. ing. This excess length of the optical transmission element in the optical cable ensures that no excessive tensile stress is generated in the optical transmission element when the optical cable is bent or twisted. For example, in an optical cable having a circular cross-section, the optical transmission element can be spirally wound around a central element that extends along the longitudinal axis of the cable. The central element is rigid to prevent tensile and compressive loads in the longitudinal direction of the optical cable.

  Known materials for soft strand jackets have the disadvantage that their melting point or softening point is below 85 ° C. Already temperatures of about 85 ° C. are therefore accompanied by softening or melting of the strand jacket of the optical transmission element. In this case, the strand jackets of the two optical transmission elements arranged adjacent to each other of the optical cable can be fused or glued together. Furthermore, the strand jacket of the optical transmission element can be glued to the cable sheath of the optical cable or to the optical waveguide surrounded by the strand jacket. Adhesion between two adjacent optical transmission element strand jackets or optical transmission element strand jacket and cable sheath adversely affects optical cable mounting and connection techniques, among others. Adhesion between the strand jacket of the optical transmission element and the optical waveguide is particularly disadvantageous for the optical transmission characteristics. When the optical transmission element is bent or twisted at the bonding point, macro bending of the optical waveguide can occur. The compressive load caused by bending between the two bonding points can lead to a microbend in the optical waveguide. Macrobends and microbends enhance the emission of light from glass fibers and thus the attenuation of optical signals. Furthermore, it is difficult to individualize the optical waveguide bonded to the strand jacket.

  By using known soft materials for the strand jacket of the optical transmission element, the temperature at which the optical transmission element can be used is limited to temperatures below 85 ° C. In particular, the temperature at which an optical transmission element can be reworked into a single optical cable is limited to temperatures below 85 ° C.

  An optical cable is manufactured by first forming an optical transmission element and then reworking a plurality of optical transmission elements into a single optical cable. Each optical transmission element is formed by feeding a plurality of optical waveguides to an extruder head that extrudes one strand jacket around the plurality of optical waveguides. The plurality of optical transmission elements are reworked into one optical cable by forming one cable sheath around the plurality of optical transmission elements. In this case, the cable sheath is supplied to an extruder head, in which a plurality of optical transmission elements, in particular, extrude a protective jacket that is stable against lateral or lateral pressure around the plurality of optical transmission elements. Is formed.

  When reworking an optical transmission element to make an optical cable, especially when extruding a protective jacket that is stable against lateral or lateral pressure, the strand jacket of the optical transmission element is a protective jacket. Temperatures in excess of 85 ° C. can be reached depending on the material and draw speed. This results in adhesion between the strand jacket and the optical waveguide of the optical transmission element, the strand jacket of another adjacent optical transmission element or the cable sheath of the optical cable.

  Another known material for the strand jacket of the optical transmission element is, for example, polybutylene terephthalate (PBT), polycarbonate (PC), a mixture of polybutylene terephthalate and polycarbonate or polypropylene.

  These materials, however, have the disadvantage of being extremely hard. Therefore, a strand jacket made of these materials cannot be removed without a special tool to expose the optical waveguide.

  Accordingly, the problem of the present invention is that the elongation at break is low and the melting point is high so that it does not soften at temperatures up to 85 ° C. so that it can be removed without special tools to expose the optical waveguide. An optical cable having an optical transmission element with a strand jacket is provided.

  According to the present invention, the above problem is solved by an optical cable having the characteristics described in the characterizing part of claim 1.

  The optical cable according to the invention has a cable sheath with at least two optical transmission elements. The transmission element is arranged in the cable sheath. One of the at least two optical transmission elements has at least one optical waveguide and a strand jacket surrounding the at least one optical waveguide. In this case, the strand jacket has a matrix material and a filler embedded in the matrix material. The melting point of the matrix material is greater than 85 ° C., and the mass ratio of the filler to the total mass of the strand jacket is at least 30%.

  The strand jacket of the optical transmission element thus has a matrix material and a filler. In so doing, the melting point of the strand jacket is defined by the melting point of the matrix material. By selecting a matrix material having a melting point greater than 85 ° C., a strand jacket is obtained that does not melt or soften when reworking the optical transmission element to make an optical cable. An optical cable having an optical transmission element with such a strand jacket is therefore very flexible and can be bent without increasing the attenuation of the optical signal in the optical waveguide. Furthermore, the elongation at break of the strand jacket is defined by the mass proportion of the filler embedded in the matrix material in the total mass of the strand jacket. For example, if the mass proportion of filler in the total mass of matrix material and filler is at least 30%, the break elongation or tensile strength of the strand jacket is reduced to such an extent that the strand jacket can be removed without special tools. . This considerably simplifies the handling of optical cables having an optical transmission element with such a strand jacket.

  Advantageously, the matrix material of the strand jacket of the optical transmission element is a thermoplastic polymer having a melting point of at least 110 ° C., and the filler embedded in the matrix material is a mineral.

  By selecting a thermoplastic polymer having a melting point of more than 110 ° C. as the matrix material, a strand jacket with an optical transmission element clearly having a melting point higher than 85 ° C. is obtained. Therefore, a process step of heating the strand jacket to a temperature in excess of 85 ° C. can also be used in reworking the optical transmission element to make an optical cable. By selecting minerals as the filler, it is assured that the filler will also withstand temperatures in excess of 85 ° C. In addition, under the minerals, there are known passive fillers that only reduce the breaking elongation of the strand jacket, and active fillers that impart additional advantageous properties to the strand jacket (akitiver Fuellstoff). It has been. For example, a suitable active filler can cause the flame resistance of the strand jacket by dehydration or prevent water diffusion in the longitudinal direction of the optical cable by water absorption.

  Advantageously, the mass proportion of filler in the strand jacket of the optical transmission element is between 60% and 70%.

  When the matrix material of the strand jacket of the optical transmission element has an excessively high hardness in addition to a sufficiently high melting point or softening point, the required reduction in the elongation of the strand jacket is reduced by the filler and It can be caused by an increase in the mass proportion of the filler in the total mass of the matrix material.

  Advantageously, the matrix material of the strand jacket of the optical transmission element comprises a polyolefin.

  The matrix material of the strand jacket of the optical transmission element is polyethylene, such as “Low Density Polyethylene (LDPE)”, “MDPE = Medium Density Polyethylene” or “HDPE = High Density”. (Polyethylene) ".

  In particular, the matrix material of the strand jacket of the optical transmission element can comprise polypropylene.

  Advantageously, the matrix material of the strand jacket of the optical transmission element comprises an elastomer or an elastomeric copolymer.

  In particular, the filling material of the strand jacket of the optical transmission element can have chalk.

  In general, as a filler, chalk embedded in a matrix material having a melting point above 85 ° C. reduces only the elongation at break of the strand jacket. Choke is a passive filler.

  Advantageously, the filler of the strand jacket of the optical transmission element comprises magnesium hydroxide or aluminum hydroxide.

  In general, metal hydroxide added as a filler in a matrix material having a melting point in excess of 85 ° C. causes the flame retardant properties of the strand jacket. Metal hydroxide is an active filler. The flame retardancy of matrix materials filled with metal hydroxides can be attributed to the release of water during oxidation of the metal hydroxide.

  The active filler can also have a swellable powder (SAP = superabsorbent polymer). The swellable powder can have polyacrylic acid or a salt of polyacrylic acid, such as sodium polyacrylate.

  Advantageously, the cable sheath of the optical cable comprises polyethylene, polypropylene or polyamide.

  When reworking an optical transmission element to make an optical cable with a cable sheath having one of these materials, the optical transmission element strand jacket is generally in the process A process step occurs where the temperature reaches a temperature above 85 ° C. Therefore, an optical cable with such a cable sheath should have an optical transmission element with a strand jacket that can withstand this temperature.

  Another object of the present invention is to provide a method of making an optical cable that avoids adhesion between the optical transmission element and another optical transmission element, cable sheath or optical waveguide.

  According to the invention, the above problem is solved by a method for producing an optical cable with the features described in the characterizing part of claim 9.

  The method according to the invention for making an optical cable comprises at least two optical transmission elements comprising forming at least two optical transmission elements and heating the strand jacket to a temperature of at least 85 ° C. And a subsequent step of forming a cable sheath around. In so doing, the formation of at least one of the two optical transmission elements comprises the steps of providing at least one optical waveguide and having a matrix polymer and a filler having a melting point greater than 85 ° C. At least one light guide by extruding a strand jacket from the mixture of filler and matrix polymer, with a subsequent step of preparing a mixture in which the mass proportion of filler in the total mass of material and matrix polymer is at least 30%; And a further subsequent step of forming a strand jacket around the waveguide.

  The method according to the invention for producing an optical cable forms an optical transmission element with a strand jacket having a high melting point and a low elongation at break. Therefore, when reworking an optical transmission element to form an optical cable, heating the strand jacket to a temperature in excess of 85 ° C. may result in a separate optical transmission element from another optical transmission element. Adhesion with the transmission element, cable sheath or optical waveguide cannot occur.

  Advantageously, the step of preparing the matrix material comprises the step of preparing a thermoplastic polymer, and the step of preparing the filler comprises the step of preparing a mineral.

  Advantageously, forming the cable sheath comprises extruding polyethylene, polypropylene or polyamide.

  The drawing shows an optical cable according to one embodiment of the present invention.

  The illustrated optical cable 1 has one cable sheath 11 and a plurality of optical transmission elements 101 and 102. The cable sheath 11 can have polyethylene (PE), polypropylene (PP), or polyamide (PA). The optical transmission elements 101 and 102 are arranged in the cable sheath 11. The optical cable 1 has a circular cross section. Within the section of the optical cable 1 having a certain length, the section of the optical transmission elements 101, 102 having a slightly larger length is arranged. This excess length of the optical transmission elements 101, 102 in the section of the optical cable 1 causes excessive mechanical stresses to be applied when the optical cable 1 is bent or twisted. It does not occur in 102. For example, the excess length of the optical transmission elements 101, 102 can be caused by contraction of the cable sheath 11 or wrapping around a central element, for example a swelled yarn (Quellgarn) 12.

  The optical cable 1 can have 12 optical transmission elements, for example, optical transmission elements 101 and 102. The twelve optical transmission elements can be color coded with a corresponding number of distinguishable colors. For example, the strand jacket 1011 of the transmission element 101 can have one of 12 distinct colors.

  The optical transmission element 101 includes a strand jacket 1011 and a plurality of optical waveguides 10101 and 10102. The strand jacket has a matrix polymer and a filler embedded in the matrix polymer. The matrix polymer has a melting point or softening point above 85 ° C. The strand jacket advantageously comprises a thermoplastic polymer having a melting point of at least 110 ° C., ie 110 ° C. or above 110 ° C. The strand jacket can comprise a polyolefin, in particular polyethylene (PE) or polypropylene (PP). In particular, the matrix polymer can have “low density polyethylene (LDPE)”, “medium density polyethylene (MDPE)” or “high density polyethylene (HDPE)”. The strand jacket may have an elastomer or a copolymer of elastomers. The filler embedded in the matrix polymer reduces the break elongation and tensile strength of the strand jacket. The mass proportion of the filler in the total mass of the strand jacket is at least 30%, i.e. 30% or more than 30%. Advantageously, the mass proportion of filler in the strand jacket is between 60% and 70%. The filler preferably has a mineral. For example, the filler can have chalk. The filler may comprise a metal hydroxide, such as magnesium hydroxide or aluminum hydroxide, or may comprise a swellable material, such as polyacrylic acid or a salt of polyacrylic acid, such as sodium polyacrylate. it can.

  The optical waveguides 10101 and 10102 are disposed in the strand jacket 1011. The illustrated optical transmission element 101 has a circular cross section. Within the section of the optical transmission element 101 having a certain length, sections of the optical waveguides 10101 and 10102 having a slightly larger length are arranged. This excess length of the optical waveguides 10101 and 10102 within the section of the optical transmission element 101 prevents excessive tensile stress from being generated in the optical waveguides 10101 and 10102 when the optical cable 1 is bent or twisted. That's it. For example, the optical waveguides 10101, 10102 can be arranged around the longitudinal axis of the section in the form of a helix.

  The optical transmission element 101 can have 12 optical waveguides, for example, optical waveguides 10101 and 10102. The twelve optical waveguides can be color coded by a corresponding number of distinguishable colors. For example, the optical waveguide can have a glass fiber and a fiber coating (coating) surrounding the glass fiber. In this case, the fiber coating of the optical waveguide can have one of 12 distinct colors.

  When the optical cable 1 is bent or twisted, the optical transmission elements 101 and 102 move in the cable sheath 11 and the optical waveguides 10101 and 10102 move in the strand jacket 1011 so that mechanical stress is minimized. To do. For this purpose, it is necessary that the optical waveguides 10101 and 10102 are slidable relatively easily with respect to the strand jacket 1011 in the longitudinal direction of the optical transmission element 101. Furthermore, it is necessary that the optical transmission elements 101 and 102 are slidable relative to each other in the longitudinal direction of the cable 1 and relative to the cable sheath 11.

  According to the present invention, the strand jacket 1011 of the optical transmission element 101 has a high melting or softening point and a low elongation at break. Thereby, adhesion between the strand jacket 1011 and the optical transmission element 102, the cable sheath 11 or the swollen yarn 12 is prevented. Further, adhesion between the strand jacket 1011 of the optical transmission element 101 and the optical waveguides 10101 and 10102 is prevented. Thereby, the optimal mobility of the optical waveguide within the optical transmission element and the optimal mobility of the optical transmission element within the optical cable remain maintained. Mechanical stress, in particular tensile and compressive stress on the optical waveguide in the optical transmission element, and tensile and compressive stress on the optical transmission element in the optical cable are thereby more effective. Can be minimized.

  Since the strand jacket 1011 of the optical transmission element 101 according to the invention has a low elongation at break, it can be removed without special tools in order to expose the optical waveguide.

  The low tensile strength of the strand jacket 1011 that leads to a low elongation at break is not a disadvantage here. This is because the high melting point or softening point of the strand jacket 1011 prevents the bond between the strand jacket 1011 and the adjacent surface in the optical cable 1, so that the optical waveguides 10101, 10102 are highly movable relative to each other. , High mobility of the optical waveguide relative to the strand jacket 1011, high mobility of the optical transmission elements 101 and 102, and high relative to the cable sheath 11 of the transmission element This is because mobility is guaranteed.

  The optical cable 1 is first formed with a plurality of optical transmission elements, for example, optical transmission elements 101 and 102, and then the plurality of optical transmission elements are reworked into one optical cable. It is manufactured by. In each case, one optical transmission element, for example the optical transmission element 101, is supplied to an extruder head in which a plurality of optical waveguides, for example optical waveguides 10101, 10102, form a strand jacket 1011 around the plurality of optical waveguides. Is formed. The strand jacket 1011 is formed, for example, by preparing a mixture of a matrix material and a filler, and extruding the strand jacket 1011 from this mixture. The matrix material then has a melting point in excess of 85 ° C. and the mass proportion of the filler in the total mass of the mixture is at least 30%. The matrix material is, for example, a thermoplastic polymer having a melting point of at least 110 ° C. The matrix polymer can in particular be a polyolefin, for example polyethylene or polypropylene, in particular LDPE, MDPE or HDPE, or an elastomer or elastomeric copolymer.

  A plurality of optical transmission elements, for example, optical transmission elements 101 and 102, are reprocessed into a single optical cable 1 by forming a cable sheath 11 around the plurality of optical transmission elements. Is done. At that time, the cable sheath 11 is supplied to an extruder head in which a plurality of optical transmission elements are extruded around the plurality of optical transmission elements with a single protective jacket that is stable against lateral or lateral pressure. Is formed. In so doing, the strand jacket 1011 can be heated to a temperature in excess of 85 ° C.

  In order to avoid adhesion between the strand jacket 1011 and the adjacent surface in the optical cable 1 from the listed materials, it has a melting point or softening point that is well above the maximum temperature reached during the production of the optical cable 1. A matrix polymer can be selected. Furthermore, to allow the matrix polymer to be removed from the optical transmission element 101 without a special tool by filling the matrix polymer with a filler having a mass percentage of at least 30% of the mass of the strand jacket. In addition, the elongation at break of the strand jacket 1011 can be sufficiently low.

1 is a diagram illustrating an optical cable according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical cable 11 Cable sheath 12 Swelling yarn 101,102 Optical transmission element 1011 Strand jacket 10101,10102 Optical waveguide

Claims (11)

In the optical cable (1), the cable (1)
A cable sheath (11);
At least two optical transmission elements (101, 102) arranged in the cable sheath (11), wherein at least one of the transmission elements (101)
At least one optical waveguide (10101, 10102);
A strand jacket (1011) surrounding at least one optical waveguide (10101, 10102), the strand jacket (1011) having a matrix material and a filler embedded in the matrix material An optical cable, characterized in that the melting point of the matrix material exceeds 85 ° C. and the mass proportion of the filler in the strand jacket (1011) is at least 30%.   The matrix material of the strand jacket (1011) of at least one transmission element (101) of the at least two optical transmission elements (101, 102) is a thermoplastic polymer having a melting point of at least 110 ° C; The optical cable according to claim 1, wherein the filler embedded in the matrix material is a mineral.   The mass percentage of filler in the strand jacket (1011) of at least one transmission element (101) of the at least two optical transmission elements (101, 102) is 60% to 70%. Optical cable as described.   The matrix material of the strand jacket (1011) of one transmission element (101) of the at least two optical transmission elements (101, 102) comprises a polyolefin having a melting point of at least 110 ° C. The optical cable according to any one of 1 to 3.   Polyethylene, polypropylene, elastomer or copolymer of elastomer in which the matrix material of the strand jacket (1011) of one transmission element (101) of at least two optical transmission elements (101, 102) has a melting point of at least 110 ° C. The optical cable according to claim 1, comprising:   The matrix material of the strand jacket (1011) of one transmission element (101) of the at least two optical transmission elements (101, 102) is a low density polyethylene, a medium density polyethylene or a high density having a melting point of at least 110 ° C. The optical cable according to claim 1, comprising density polyethylene.   The filler in the strand jacket (1011) of one transmission element (101) of at least two optical transmission elements (101, 102) is chalk, magnesium hydroxide, aluminum hydroxide, polyacrylic acid or polyacrylic. The optical cable according to claim 1, comprising an acid salt.   9. Optical cable according to claim 1, wherein the cable sheath (11) comprises polyethylene, polypropylene or polyamide. In the method of manufacturing the optical cable (1),
Forming at least two optical transmission elements (101, 102), wherein at least one of the at least two optical transmission elements (101, 102) is transmitted; Formation takes the following steps:
Preparing at least one optical waveguide (10101, 10102);
Providing a mixture of matrix material and filler, wherein the matrix material has a melting point greater than 85 ° C., and the weight percentage of filler in the total mass of the mixture is at least 30%;
Forming a strand jacket (1011) surrounding the at least one optical waveguide (10101, 10102) by extruding a strand jacket (1011) from the mixture,
Subsequently, a step of forming a cable sheath (11) surrounding at least two optical transmission elements (101, 102) is provided, the step of heating the strand jacket (1011) to a temperature of at least 85 ° C. A method of making an optical cable, comprising:   Providing the mixture comprises preparing a mixture comprising a thermoplastic polymer having a melting point of at least 110 ° C. and a mineral having a mass percentage of 60% to 70% of the total mass of the mixture; The method of claim 9.   The method according to claim 9 or 10, wherein the formation of the cable sheath (11) comprises an extrusion of polyethylene, polypropylene or polyamide.

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