JP2013250499A - Covering material for optical fiber cable, and optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress shrinkage of a covering material for optical fiber cables, while ensuring flexibility of the covering material to some extent.SOLUTION: This covering material for optical fiber cables contains 10% by mass or more of a polypropylene elastomer, and preferably does not contain a paraffin. It is also preferable that the covering material for optical fiber cables is composed of 35-55% by mass of a polymer containing a polypropylene elastomer and the balance made up of an additive. The covering material for optical fiber cables is used as a sheath 16 that covers the outer circumference of an optical fiber.

Description

  The present invention relates to an improvement in a coating material for an optical fiber cable used for in-vehicle use or the like.

  The optical fiber cable is configured so that a sheath as a covering material covers the periphery of the optical fiber.

  However, if the sheath covering the periphery of the optical fiber contracts, the optical fiber cable may meander and the optical transmission loss of the optical fiber may increase.

  Further, in consideration of the handling property of the optical fiber cable, the sheath needs to have a certain degree of flexibility.

  Therefore, an object of the present invention is to suppress the shrinkage of the coating material of the optical fiber cable while ensuring a certain degree of flexibility.

  In order to solve the above problem, the coating material for an optical fiber cable according to the first aspect contains 10 mass% or more of polypropylene elastomer.

  A 2nd aspect is a coating material for optical fiber cables which concerns on a 1st aspect, Comprising: A paraffin is not included.

  The coating material for optical fiber cables according to the third aspect is the coating material for optical fiber cables according to the first or second aspect, wherein 35 mass% to 55 mass% of the polymer containing the polypropylene elastomer, and the remainder It consists of additives.

  The optical fiber cable which concerns on a 4th aspect is provided with the sheath for optical fiber and the coating material for optical fiber cables as described in any one of 1st-3rd, and covers the outer periphery of the said optical fiber.

  According to the coating material for optical fiber cables according to the first to third aspects, since the polypropylene elastomer is contained in an amount of 10% by mass or more, the flexibility of the coating material for the optical fiber cable can be secured to some extent. In addition, since flexibility can be ensured without including paraffin or the like, shrinkage of the covering material can be suppressed.

  According to the 2nd aspect, since paraffin is not included, shrinkage | contraction of a coating | covering material can be suppressed.

  According to the fourth aspect, it is possible to obtain an optical fiber cable which is excellent in flexibility to some extent and has a small optical transmission loss.

It is a figure which shows the structural example of an optical fiber cable. It is a table | surface which shows the relationship between the addition amount of paraffin oil, and the frequency | count of a required annealing process. It is a graph which shows the relationship between the number of annealing processes, and a heat shrinkage rate in each of the case where paraffin oil is added and not added. It is explanatory drawing which shows the evaluation method of a softness | flexibility. It is a table | surface which shows the relationship between the sheath of various mixing | blendings, and a softness | flexibility. It is a table | surface which shows the relationship between the sheath of various mixing | blendings, and a softness | flexibility.

  Hereinafter, the coating material for optical fibers and the optical fiber cable according to the embodiment will be described.

  FIG. 1 is a diagram illustrating a structure example of an optical fiber cable 10. The optical fiber cable 10 includes an optical fiber 12, a strength member 14, and a sheath 16 as an optical fiber coating material.

  The optical fiber 12 is an optical transmission medium including a core and a clad. The optical fiber 12 may be made of glass or plastic.

  The strength member 14 is a member for reinforcing the tensile force so that the tensile force is not transmitted to the internal optical fiber 12 when the optical fiber cable 10 is pulled, and is made of, for example, an aramid fiber. Here, the strength member 14 is provided so as to cover the optical fiber 12. The tensile body may be a wire or is not essential.

  The sheath 16 is a protective material that covers the outer periphery of the optical fiber 12. Here, the sheath 16 is formed in a tube shape and covers the optical fiber 12 and the strength member 14 without being tightened. Thus, the structure in which the sheath 16 covers the optical fiber 12 in a loose state is called a loose structure. However, the sheath may be covered in a state of being in close contact with the optical fiber (and the tensile body if necessary).

  By the way, in the optical fiber cable 10 as described above, if the sheath 16 contracts with resin, the internal optical fiber 12 may meander and the optical transmission loss of the optical fiber 12 may increase.

  Therefore, the inventors studied to perform an annealing process on the sheath 16 in order to suppress the resin shrinkage of the sheath 16 after the optical fiber cable 10 was manufactured. The annealing step is a step in which the sheath 16 is heated and contracted in advance, and is performed, for example, by heating at a constant temperature for a predetermined time. In view of the optical transmission loss of the optical fiber cable 10 and the like, it was considered that the residual heat shrinkage after the annealing step is preferably 0.3% or less in order to eliminate practical problems.

  However, in order to make the residual heat shrinkage rate 0.3% or less, it has been found that the annealing process needs to be performed a plurality of times on the sheath 16, and the burden of the annealing process becomes excessive.

  Therefore, the inventors of the present application examined the cause of the large heat shrinkage rate, and the paraffin oil added to improve the flexibility of the sheath 16 is a factor for increasing the heat shrinkage rate. Investigated.

  FIG. 2 is a table showing the relationship between the addition amount (parts by mass) of paraffin oil, the heat shrinkage rate (%), and the number of annealing steps necessary to make the residual heat shrinkage rate 0.3% or less. . FIG. 3 is a graph showing the relationship between the number of annealing steps and the heat shrinkage rate when 12.5 parts by mass of paraffin oil is added and when paraffin oil is not added. In one annealing process, heating was performed for 4 hours under a temperature condition of 100 ° C.

  In the example in which 12.5 parts by mass of paraffin oil is added from the figure, the initial heat shrinkage ratio is 1.5%, and it is necessary to perform the annealing process three times in order to reduce the heat shrinkage ratio to 0.3% or less. I know that there is. In addition, in the example in which 10 parts by mass of paraffin oil is added, the initial heat shrinkage rate is 1.2%, and the annealing step needs to be performed three times in order to reduce the heat shrinkage rate to 0.3% or less. I understand. Further, in the example in which 7.5 parts by mass of paraffin oil is added, the initial heat shrinkage rate is 0.6%, and in order to make the heat shrinkage rate 0.3% or less, it is necessary to perform the annealing process twice. I know that there is. In the example in which no paraffin oil is added, the initial heat shrinkage rate is 0.4%, and it can be seen that the annealing process may be performed once in order to reduce the heat shrinkage rate to 0.3% or less.

  From these, it was found that there was a significant correlation between the amount of paraffin oil added and the heat shrinkage rate.

  However, the reason why the paraffin oil is added is to give the sheath 16 flexibility, and considering the handleability of the optical fiber cable 10 and the like, it is necessary to give the sheath 16 some flexibility. It is said.

  Therefore, the present inventors have found that a polypropylene elastomer is used to impart flexibility to the sheath 16. Polypropylene elastomer is obtained by dispersing rubber such as ethylene propylene rubber (EPDM) in polypropylene. By adding such polypropylene elastomer to the sheath 16, a sheath 16 having excellent flexibility can be obtained.

  In order to obtain a generally preferred flexibility, the sheath 16 is made of 10 mass% or more of polypropylene elastomer, preferably 15 mass% or more, more preferably 20 mass% or more, and even more preferably 25 mass%. It is good to include the above.

  Further, from the viewpoint of wear resistance, which is an on-vehicle requirement, the sheath 16 preferably contains 55% by mass or less of polypropylene elastomer, more preferably 35% by mass or less.

  Of course, the sheath 16 preferably does not contain paraffin oil, but may be slightly added as long as the processing load of the annealing process is not excessive.

  Moreover, it is preferable that the sheath 16 consists of 35 mass%-55 mass% of polymers containing a polypropylene elastomer, and the remainder additive. The reason why the lower limit of the polymer is 35% by mass is based on the allowable flexibility, and the reason why the upper limit of the polymer is 55% by mass is based on the wear resistance. Additives are modifiers such as flame retardants, antioxidants, copper damage inhibitors, excluding polymers and paraffin oil.

  Actually, various sheaths 16 were manufactured, and the relationship between the blending amount of polypropylene elastomer and flexibility was tested.

  FIG. 4 is an explanatory diagram showing a flexibility evaluation method. That is, 30 sheaths 16 having a wire length of 350 mm (with the internal optical fiber 12 and the tensile body 14 removed) are converged, and vinyl tape T is spirally wound around the sheath (so-called rough winding and so on). The so-called winding method) was designated as test sample S. Two cylinders E having a diameter of 19 mm were placed in a high-temperature bath at 30 ° C. with a gap therebetween. The interval W between the central axes of the cylinders E is 100 mm. The test sample S is placed so as to straddle the two cylinders E, the center of the test sample S is pulled downward, and the maximum load until the test sample S comes off the cylinder E is evaluated for flexibility. The measured value was used.

  FIG.5 and FIG.6 is a table | surface which shows the relationship between the sheath 16 of various mixing | blendings, and a softness | flexibility.

  As the polymer to be blended, polypropylene-based polymers and MAH-SEBS (maleic anhydride-modified styrene-ethylene / butylene-styrene block copolymer, Tuftec 1913, manufactured by Asahi Kasei Kogyo Co., Ltd.) were prepared. As the polypropylene-based polymer, polypropylene (Novatech EC9, manufactured by Nippon Polypro Co., Ltd.) and three types of polypropylene elastomer (AdflexQ100F, AdflexQ200F, AdflexC200F, manufactured by LyondellBasell Industries) were prepared.

  As additives, flame retardants, antioxidants, copper damage inhibitors, and oil masterbatches were prepared.

  As the flame retardant, magnesium hydroxide (Kisuma 5, Kisuma 5C, manufactured by Kyowa Chemical Industry Co., Ltd.), non-decabrobromine-based (SAYTEX 8010, manufactured by ALBEMARLE CORPORATION), and antimony trioxide were prepared. As an antioxidant, hindered phenol (Irg. 1010) was prepared. As a copper damage inhibitor, an amide system (CDA-10, manufactured by ADEKA Corporation) was prepared. In addition, an oil master batch (OILMB-C) was prepared as a paraffin oil.

  In the blending examples of Comparative Examples 1 and 2, an oil masterbatch (paraffin oil) is included instead of the polypropylene elastomer. The blending amount of the oil masterbatch (paraffin oil) is determined as an appropriate amount for obtaining flexibility (refer to the flexibility evaluation result (N)) that is preferable from the handling property of the optical fiber cable 10 and the like. In other words, the flexibility evaluation result (N) is preferably 75 or less in view of the manageability of the optical fiber cable 10 and the like.

  Example 1 is a blending example containing a small amount of polypropylene elastomer (7.2% by mass), Example 2 is a blending example containing a moderate amount of polypropylene elastomer (16.8% by mass), and Example 3 is a polypropylene. This is a blending example containing a large amount of elastomer (26.4% by mass). In Example 1, the flexibility evaluation result (N) is 76.5, which exceeds the preferable flexibility evaluation result 75. In Example 2, the flexibility evaluation result (N) is 67.5, and in Example 3, the flexibility evaluation result (N) is 39.4, which is less than or equal to the preferable flexibility evaluation result 75. . Examples 4 and 5 are examples in which the type of polypropylene elastomer was changed. Example 4 contains 12.6% by weight of polypropylene elastomer and Example 5 contains 16.8% by weight of polypropylene elastomer. The respective flexibility evaluation results (N) are 69.4 and 67.1, which are preferably the flexibility evaluation results 75 or less. From these, it can be understood that the flexibility that is preferable can be obtained when the sheath 16 contains 10 mass% or more of the polypropylene elastomer. Moreover, it turns out that it is good to contain a polypropylene elastomer preferably 15 mass% or more, More preferably, 20 mass% or more, More preferably, 25 mass% or more.

  Moreover, in these cases, the flexibility which is preferable even if paraffin oil is not included can be obtained.

  Further, according to the above blending example, as a coating material for optical fiber, which is excellent in flexibility and can suppress thermal shrinkage by a material comprising 35 mass% to 55 mass% of a polymer containing polypropylene elastomer and the remaining additive. The sheath 16 and the optical fiber cable 10 can be obtained.

  As described above, the present invention has been described in detail. However, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

10 optical fiber cable 12 optical fiber 16 sheath

Claims (4)

  An optical fiber cable covering material containing 10% by mass or more of polypropylene elastomer. The coating material for an optical fiber cable according to claim 1,
Fiber optic cable coating without paraffin. A coating material for an optical fiber cable according to claim 1 or 2,
A coating material for an optical fiber cable comprising 35% by mass to 55% by mass of a polymer containing the polypropylene elastomer and the remaining additive. Optical fiber,
A sheath formed by the coating material for an optical fiber cable according to any one of claims 1 to 3 and covering an outer periphery of the optical fiber;
An optical fiber cable comprising:

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