An easily peelable optical fiber ribbon introduced optical cable and its manufacturing method

Abstract

The present invention discloses an easily peelable fiber ribbon inlet optical cable. The cross-section of its outer sheath is oblong in shape. The middle part of the outer sheath has a rectangular inner cavity for accommodating a fiber ribbon or a fiber ribbon array, and symmetric strengthening members are provided on both sides of the rectangular inner cavity; the outer sheath includes a first phase and a second phase extending axially; wherein the second phase is distributed in the first phase; the first phase is formed of a sheath material, and the second phase is formed of a thermoplastic material different from the first phase; on the cross-section of the sheath, the second phase forms a plurality of discrete easily tearable parts, and the easily tearable parts are distributed between the rectangular inner cavity and at least one strengthening member. The easily peelable fiber ribbon inlet optical cable provided by the present invention forms the first phase and the second phase with different thermoplastic materials, and uses the interface between the materials to form an easily tearable peeling groove, so as to adjust the position of the peeling groove closer to the rectangular inner cavity and the peeling direction more accurately pointing to the rectangular inner cavity.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communication, and more specifically, relates to an easily peelable fiber ribbon introducing optical cable and a preparation method thereof. Background Art

[0002] With the progress of technology, communication technology has developed rapidly. Along with the evolution of optical communication networks towards large capacity, high speed, and low latency, fiber optic cable technology has also been continuously improved. How to further increase the core density in the optical cable and optimize the optical cable structure as much as possible without affecting the transmission efficiency and capacity. In this trend, ribbon optical cable technology has emerged. A ribbon optical cable is an optical cable processed with units of multiple single optical fibers that are colored, stacked into a ribbon, and secondarily sheathed. It has the characteristics of being integrable, reducing the occupation of pipeline resources, and being easily fused.

[0003] A fiber ribbon introducing optical cable generally has a flat structure, with a fiber ribbon or a fiber ribbon array in the middle and strengthening members on both sides. In order to well protect the internal fiber ribbon, its sheath is often made of polyethylene or low-smoke halogen-free flame-retardant polyolefin materials. The sheath has high strength, and various tools are needed for cable stripping. Generally speaking, since the fiber ribbon optical cable is long and strip-shaped, the weakest part of the sheath without a strengthening member, which is the middle part of the sheath, is often the place where the stripping opening is most easily formed. However, if the stripping is not careful, it may damage the fiber ribbon inside the optical cable or the construction operator.

[0004] Improving the stripping construction efficiency and safety of optical cables is a key issue of concern in the fiber optic cable industry. Currently, the stripping technology for flat optical cables is mainly to form a notch on the sheath, such as a butterfly optical cable. For a fiber ribbon introducing optical cable, which also has a flat shape, generally, in order to accurately strip, a stripping groove is formed in the middle position of the inner cavity for accommodating the fiber ribbon. This design cannot provide sufficient mechanical strength because the outer sheath notch protects the fiber ribbon array inside. And using a tool with a blade for stripping is likely to damage the internal fiber ribbon. Chinese Patent CN104914539A provides an easily peelable fiber ribbon introducing optical cable. Since the cable is stripped using a stripping groove, the outer sheath has a structural defect, so the stripping groove cannot be too close to the inner cavity for accommodating the fiber ribbon. Once the direction of applying the stripping force is inaccurate, the inner cavity will be missed, resulting in the inability to strip relying on the stripping groove. At the same time, since the integrity of the outer sheath is damaged by the stripping groove, not many stripping grooves can be formed, resulting in the inability to provide sufficient protection of strength, affecting the quality and service life of the optical cable. Summary of the Invention

[0005] In view of the above defects or improvement requirements of the prior art, the present invention provides an easily peelable fiber ribbon inlet optical cable and a preparation method thereof. The purpose is to form a second phase different from the sheath material in the sheath, optimize the distribution and position of the second phase for the rectangular inner cavity, and utilize the cross-section between different materials to form a peeling notch, so as to accurately and safely peel the rectangular inner cavity, with high peeling success rate and peeling safety, and even without the aid of external tools, thereby solving the technical problems that the existing rectangular inner cavity fiber ribbon inlet optical cable is difficult to peel, requires the aid of external tools, is easy to damage the fiber ribbon, or the peeling notch is easy to deviate from the rectangular inner cavity, resulting in a high failure rate of manual peeling.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an easily peelable fiber ribbon inlet optical cable, characterized in that the outer sheath has a long and flat cross-sectional shape, and the middle of the outer sheath has a rectangular inner cavity for accommodating a fiber ribbon or a fiber ribbon array, and symmetrical strengthening members are provided on both sides of the rectangular inner cavity;

[0007] The outer sheath includes a first phase and a second phase extending axially; wherein the second phase is distributed in the first phase; the first phase is formed of a sheath material, and the second phase is formed of a thermoplastic material different from the first phase;

[0008] On the cross-section of the sheath, the second phase forms a plurality of discrete easily tearable parts, and the easily tearable parts are distributed between the rectangular inner cavity and at least one strengthening member; for an easily tearable part, the point closest to the rectangular inner cavity is the vertex of the rectangular inner cavity, and the distance is between 0.1 and 0.8 mm.

[0009] Preferably, for the easily peelable fiber ribbon inlet optical cable, for the easily tearable part, the point closest to the rectangular inner cavity on the cross-sectional edge of the easily tearable part is the vertex, and the straight line passing through the vertex and having the minimum sum of distances to all points on the cross-sectional edge of the easily tearable part is the normal line of the easily tearable part; for an easily tearable part, the vertex of the rectangular inner cavity closest to the easily tearable part is on the normal line of the easily tearable part.

[0010] Preferably, for the easily peelable fiber ribbon inlet optical cable, the normal line of the easily tearable part is between the tangent line of the strengthening member passing through the vertex of the rectangular inner cavity closest to the easily tearable part and the straight line passing through the vertex of the rectangular inner cavity closest to the easily tearable part and perpendicular to the center line of the strengthening member.

[0011] Preferably, for the easily peelable fiber ribbon inlet optical cable, the direction of the normal line of the easily tearable part is between the tangent line of the strengthening member passing through the vertex of the rectangular inner cavity closest to the easily tearable part and the angular bisector of the top angle of the rectangular inner cavity closest to it.

[0012] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the normal direction of the easily tearable part is in a straight line with the angular bisector of the vertex angle of the rectangular inner cavity closest to it.

[0013] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the ratio of the length t of the easily tearable part in the normal direction to the thickness T of the sheath in the normal direction is more than 60%.

[0014] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the cross-section of the easily tearable part is strip-shaped and has an opening on the outer sheath edge.

[0015] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the opening of the easily tearable part at the sheath edge is linear.

[0016] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the easily tearable part has a cross-section that narrows bidirectionally on the side close to the vertex of the rectangular inner cavity and the outer side close to the sheath edge.

[0017] Preferably, for the easily peelable optical fiber ribbon introduced into the optical cable, the peeling force between the first phase and the second phase is in the range of 5 - 50 N; the first phase is made of HDPE, MDPE or LDPE material; the second phase is formed of an easily tearable material;

[0018] The elongation at break of the second phase is 10 - 100%, and the tensile strength is 5 - 20 MPa. The preferred material formula contains, by mass percentage: cycloolefin copolymer (coc): 20% - 50%, low density polyethylene: 25% - 50%, linear low density polyethylene: 15% - 30%; the density of the cycloolefin copolymer (coc) is 1.010 - 1.050 kg / m 3 , and the physical property melt index is 1.3 - 2.0 g / 10 min.

[0019] According to another aspect of the present invention, there is provided a method for manufacturing the easily peelable optical fiber ribbon introduced into the optical cable, including the following steps:

[0020] Using a coextrusion head with a preset rectangular central hole and through holes for two side strengthening members to penetrate, the coextrusion head has a die cover, and the die cover has a first-phase material outlet and a second-phase material outlet at preset positions respectively;

[0021] Let the cable core composed of the optical fiber ribbon array pass through the rectangular central hole, and the strengthening members pass through the through holes for the two side strengthening members to penetrate. Extrude the first-phase material and the second-phase material simultaneously outside the cable core and the strengthening members, so that the second-phase material is distributed at a preset position inside the first-phase material;

[0022] After the first-phase material and the second-phase material are cured, the optical fiber ribbon introduced into the optical cable is obtained.

[0023] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0024] The easily peelable fiber ribbon introduced into the optical cable provided by the present invention uses different thermoplastic materials to form a first phase and a second phase, and utilizes the interface between the materials to form an easily tearable peeling groove, so as to adjust the position of the peeling groove closer to the rectangular inner cavity and the peeling direction more accurately point to the rectangular inner cavity. While avoiding damage to the fiber ribbon caused by peeling from the long side of the rectangular inner cavity, the accuracy of peeling on the side of the rectangular inner cavity is improved, and peeling failure is hardly caused by the application force direction.

[0025] At the same time, the second phase is used to form the peeling groove, maintaining the integrity of the outer sheath of the optical cable, thereby providing better protection and extending the service life of the optical cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic cross-sectional structure diagram of the fiber ribbon introduced into the optical cable provided in Embodiment 1 of the present invention;

[0027] Figure 2 is a schematic cross-sectional structure diagram of the fiber ribbon introduced into the optical cable provided in Embodiment 2 of the present invention.

[0028] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 is a fiber ribbon array, 2 is a water-blocking material, 3 is a sheath, 3-1 is a rectangular inner cavity, 3-2 is an easily tearable part, and 4 is a reinforcing member. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The easily peelable fiber ribbon introduced into the optical cable with a rectangular inner cavity provided by the present invention has a long and flat outer sheath cross-section. The middle of the outer sheath has a rectangular inner cavity for accommodating a fiber ribbon or a fiber ribbon array, and symmetrical reinforcing members are provided on both sides of the rectangular inner cavity.

[0031] The outer sheath includes an axially extending first phase and a second phase; wherein the second phase is distributed in the first phase; the first phase is formed of a sheath material, and the second phase is formed of a thermoplastic material different from the first phase; preferably, the second phase is formed of an easily tearable material; the peeling force between the first phase and the second phase is between 5 and 50 N.

[0032] On the cross section of the sheath, the second phase forms a plurality of discrete easy-tear portions, and the easy-tear portions are distributed between the rectangular inner cavity and at least one reinforcement member; for an easy-tear portion, the point closest to the rectangular inner cavity is the vertex of the rectangular inner cavity, and the distance is between 0.1 and 0.8 mm. The easy-tear portion is used instead of the stripping groove to form the stripping opening. Since the integrity of the outer sheath is maintained, it can be closer to the rectangular inner cavity. At the same time, the position of the easy-tear portion is set according to the characteristics of the rectangular inner cavity. The easy-tear portion is closest to the vertex of the rectangular inner cavity instead of the middle of the long side or short side of the rectangular inner cavity. Therefore, when stripping with the help of the easy-tear portion, a notch will be accurately formed in the angular direction of the rectangular inner cavity, which changes the existing optical cable stripping method of forming a notch in the middle of the long side of the rectangular inner cavity, and can almost avoid the optical fiber ribbon stored in the rectangular inner cavity, greatly reducing the probability of damaging the optical fiber ribbon due to the use of tools to form a notch, and at the same time improving the success rate of stripping. Regardless of whether a guide notch is formed on the end face, the stripping will almost never fail and miss the rectangular inner cavity.

[0033] The point on the cross-sectional edge of the easy-to-tear portion that is closest to the rectangular inner cavity is the vertex, and the straight line that passes through the vertex and has the smallest sum of distances to all points on the cross-sectional edge of the easy-to-tear portion is the normal of the easy-to-tear portion. Preferably, the vertex of the rectangular inner cavity that is closest to the easy-to-tear portion is on the normal of the easy-to-tear portion. An easy-to-tear interface is formed between the first phase and the second phase materials, so that the tearing direction of the easy-to-tear portion is generally the normal direction of the easy-to-tear portion. The normal angle of the easy-to-tear portion is adjusted as above, so that in the tearing direction of the easy-to-tear portion, the easy-to-tear portion has the shortest tearing distance with the rectangular inner cavity, so that the sheath is easier and more accurately to tear the rectangular inner cavity when it is subjected to the peeling force.

[0034] In a preferred embodiment, the normal of the easy-to-tear portion is between the tangent of the reinforcement member passing through the vertex of the rectangular inner cavity closest to the easy-to-tear portion and the straight line passing through the vertex of the rectangular inner cavity closest to the easy-to-tear portion and perpendicular to the line connecting the center of the reinforcement member. In a preferred embodiment, there are two easy-to-tear portions between the rectangular inner cavity and the reinforcement member on one side. In such a design, since the normal direction of the easy-to-tear portion does not exceed the tangent direction of the reinforcement member, the reinforcement member can be used as a force point to apply a peeling force, so that the rectangular inner cavity can be peeled off more easily, rather than separating the reinforcement member from the outer sheath. When there are two easy-to-tear portions on both sides of the rectangular inner cavity, it is only necessary to apply a relative peeling force toward the outside to the reinforcement members on both sides to easily peel off the rectangular inner cavity without the help of a force-applying tool, or only a small opening is formed between the easy-to-tear portion and the rectangular cavity during peeling to facilitate hand-held force, so that the optical cable can be stripped by hand. More preferably, the normal direction of the easy-to-tear portion is between the tangent of the reinforcement passing through the vertex of the rectangular inner cavity closest to the easy-to-tear portion and the angle bisector of the vertex angle of the rectangular inner cavity closest to it. Preferably, the normal direction of the easy-to-tear portion and the angle bisector of the vertex angle of the rectangular inner cavity closest to it are on a straight line.

[0035] Preferably, the cross-section of the easily tearable part is strip-shaped and has an opening on the edge of the outer sheath. Since the easily tearable part has an opening on the edge of the outer sheath, when a stripping force is applied by the edge of the outer sheath, the sheath can be easily damaged, and even tools are not needed. However, if the opening of the easily tearable part on the sheath edge is too large, the integrity of the outer sheath may be damaged, making it difficult to provide high-strength protection and affecting the service life of the optical cable. Preferably, the opening of the easily tearable part on the sheath edge is linear, that is, the opening is a narrow line extending axially. Therefore, the strip-shaped easily tearable part preferably has a cross-section that narrows bidirectionally on the vertex side close to the rectangular inner cavity and the outer side close to the sheath edge, such as an oval, spindle-shaped, or rhombic shape.

[0036] In a preferred embodiment, the ratio of the length t of the easily tearable part in the normal direction to the sheath thickness T in the normal direction is more than 60%.

[0037] The first phase is made of HDPE, MDPE or LDPE material.

[0038] The elongation at break of the second phase is 10-100%, and the tensile strength is 5-20 MPa. The preferred material formula contains, by mass percentage: cycloolefin copolymer (coc): 20%-50%, low-density polyethylene: 25%-50%, linear low-density polyethylene: 15%-30%; the density of the cycloolefin copolymer (coc) is 1.010-1.050 kg / m 3 , and the physical property melt index is 1.3-2.0 g / 10 min.

[0039] The easily strippable optical fiber ribbon-introduced optical cable with a rectangular inner cavity provided by the present invention is prepared according to the following method:

[0040] Use a co-extrusion head with a preset rectangular central hole and through holes for two-sided stiffeners to penetrate. The co-extrusion head has a die cover, and the die cover is respectively provided with a first-phase material outlet and a second-phase material outlet at preset positions;

[0041] Pass the cable core composed of the optical fiber ribbon array through the rectangular central hole, and pass the stiffeners through the through holes for two-sided stiffeners to penetrate. Extrude the first-phase material and the second-phase material simultaneously outside the cable core and the stiffeners, so that the second-phase material is distributed at a preset position inside the first-phase material;

[0042] After the first-phase material and the second-phase material are cured, the optical fiber ribbon-introduced optical cable is obtained.

[0043] Conventional skeleton-type fiber ribbon optical cables or loose tube-type fiber ribbon optical cables have 4 - 5 processes. With the optical cable structure design of the present invention, there are only 3 processes, effectively reducing the cost of the optical cable. At the same time, the sheaths of traditional skeleton-type fiber ribbon optical cables or loose tube-type fiber ribbon optical cables are usually made of complete polyethylene materials. When longitudinally stripping the sheath, special tools are required. Moreover, due to the high strength of the sheath, it is difficult to strip, and it is easy to damage the optical fibers or operators. The co-extruded sheath structure design of the present invention can effectively avoid the occurrence of the above situations.

[0044] The following are examples:

[0045] Example 1

[0046] The optical cable structure of Example 1 is as Figure 1 shown, which is an easily strippable fiber ribbon optical cable with a rectangular cross-section, including a cable core, symmetrically arranged strengthening members 4, and a sheath 3. The cable core includes a stacked fiber ribbon array 1. The number of fiber ribbon layers included in the fiber ribbon array can be 1 - 24 layers, and the optical fibers therein can be multimode optical fibers or single-mode optical fibers. Dry water-blocking materials 2 are symmetrically arranged on the upper and lower sides of the fiber ribbon array 1. The dry water-blocking materials can be water-blocking yarns or water-blocking tapes. The cable core is coated with a sheath 3 having a rectangular cross-section. A rectangular inner cavity 3-1 is provided in the sheath to accommodate the fiber ribbon array 1, and two strengthening members 4 are symmetrically embedded in the sheath. The strengthening members can be non-metallic or metallic strengthening members.

[0047] To improve the stripping performance of the sheath, a first-phase material and a second-phase material are co-extruded symmetrically at the four corners in the rectangular cavity of the sheath. An easily tearable interface is formed between the second-phase material and the sheath body. The material of the sheath body can be HDPE, MDPE, or LDPE. The mass percentages of the components of the second-phase co-extruded material in the sheath are as follows: cycloolefin copolymer (coc): 20% - 50%, low-density polyethylene: 25% - 50%, linear low-density polyethylene: 15% - 30%; the density of the cycloolefin copolymer (coc) is 1.010 - 1.050 kg / m 3 , and the physical property melt index is 1.3 - 2.0 g / 10 min. The peeling force between the first phase and the second phase is between 5 - 50 N.

[0048] On the cross-section of the sheath, the second phase forms 4 discrete tear-weakening parts 3-2. There are 2 tear-weakening parts distributed between the rectangular inner cavity and each strengthening member. The 4 tear-weakening parts are symmetrically arranged and respectively face the four top corners of the rectangular inner cavity. For a tear-weakening part, the point closest to the rectangular inner cavity is the vertex of the rectangular inner cavity, and the distance is between 0.1 and 0.8 mm. For the tear-weakening part, the vertex of the rectangular inner cavity closest to the tear-weakening part is on the normal line of the tear-weakening part. The normal line of the tear-weakening part is between the tangent line of the strengthening member passing through the vertex of the rectangular inner cavity closest to the tear-weakening part and the straight line passing through the vertex of the rectangular inner cavity closest to the tear-weakening part and perpendicular to the center connection line of the strengthening member, as Figure 1 shown. Preferably, the normal line direction of the tear-weakening part is on the same straight line as the angular bisector of the top corner of the rectangular inner cavity closest to it.

[0049] The cross-section of the tear-weakening part is elliptical strip-shaped, and it has a linear opening on the outer sheath edge.

[0050] The length t of the tear-weakening part in the normal line direction accounts for 80% of the sheath thickness T in its normal line direction.

[0051] Embodiment 2

[0052] The optical cable structure of Embodiment 2 is as Figure 2 shown, which is an easily strippable optical fiber ribbon cable with a rectangular cross-section, including a cable core, symmetrically arranged strengthening members 4 and a sheath 3. The cable core includes a stacked optical fiber ribbon array 1. The number of optical fiber ribbon layers included in the optical fiber ribbon array can be 1 to 24 layers, and the optical fibers therein can be multimode optical fibers or single-mode optical fibers. Dry water-blocking materials 2 are symmetrically arranged on the upper and lower sides of the optical fiber ribbon array 1. The dry water-blocking materials can be water-blocking yarns or water-blocking tapes. The cable core is coated with a sheath 3 with a rectangular cross-section. A rectangular inner cavity 3-1 is arranged in the sheath to accommodate the optical fiber ribbon array 1, and two strengthening members 4 are symmetrically embedded in the sheath. The strengthening members can be non-metallic or metallic strengthening members.

[0053] To improve the stripping performance of the sheath, a first-phase material and a second-phase material are co-extruded symmetrically at the four corners in the rectangular cavity of the sheath. An easily torn interface is formed between the second-phase material and the sheath body. The material of the sheath body can be HDPE, MDPE or LDPE. The mass percentages of the components of the second-phase co-extruded material in the sheath are as follows: cycloolefin copolymer (coc): 20%-50%, low-density polyethylene: 25%-50%, linear low-density polyethylene: 15%-30%; the density of the cycloolefin copolymer (coc) is 1.010-1.050 kg / m 3 , and the physical property melt index is 1.3-2.0 g / 10 min. The peeling force between the first phase and the second phase is between 5 and 50 N.

[0054] On the cross-section of the sheath, the second phase forms two discrete tear-weakening parts 3-2. Between the rectangular inner cavity and one side of the reinforcing member, the two tear-weakening parts are symmetrically arranged and respectively face two vertices on the same side of the rectangular inner cavity. For one tear-weakening part, the point closest to the rectangular inner cavity is the vertex of the rectangular inner cavity, and the distance is between 0.1 and 0.8 mm. For the tear-weakening part, the vertex of the rectangular inner cavity closest to the tear-weakening part is on the normal line of the tear-weakening part. The normal line of the tear-weakening part is between the tangent line of the reinforcing member passing through the vertex of the rectangular inner cavity closest to the tear-weakening part and the line passing through the vertex of the rectangular inner cavity closest to the tear-weakening part and perpendicular to the central connection line of the reinforcing member. In this embodiment, the normal line direction of the tear-weakening part and the tangent line of the reinforcing member passing through the vertex of the rectangular inner cavity closest to the tear-weakening part are on the same straight line.

[0055] The cross-section of the tear-weakening part is wedge-shaped strip, and it has an opening on the outer sheath edge.

[0056] The ratio of the length t of the tear-weakening part in the normal line direction to the sheath thickness T in the normal line direction is 75%.

[0057] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An easily peelable fiber ribbon introducing optical cable, characterized in that, The outer sheath has a long and flat cross-sectional shape. The middle part of the outer sheath has a rectangular inner cavity for accommodating an optical fiber ribbon or an optical fiber ribbon array, and symmetrical strengthening members are provided on both sides of the rectangular inner cavity. The outer sheath includes an axially extending first phase and a second phase; the second phase is distributed in the first phase; the first phase is formed of a sheath material, and the second phase is formed of a thermoplastic material different from the first phase. On the cross-section of the outer sheath, the second phase forms a plurality of discrete tearable portions, and tearable portions are distributed between the rectangular inner cavity and at least one strengthening member; for a tearable portion, the point closest to the rectangular inner cavity is the vertex of the rectangular inner cavity, and the distance is between 0.1 and 0.8 mm. For the tearable portion, the point closest to the rectangular inner cavity on the cross-sectional edge is the vertex, and the straight line passing through the vertex and having the minimum sum of distances to all points on the cross-sectional edge of the tearable portion is the normal line of the tearable portion; for a tearable portion, the vertex of the rectangular inner cavity closest to the tearable portion is on the normal line of the tearable portion.

2. The easily peelable fiber ribbon introducing optical cable according to claim 1, characterized in that, The normal line of the tearable portion is between the tangent line of the strengthening member passing through the vertex of the rectangular inner cavity closest to the tearable portion and the straight line passing through the vertex of the rectangular inner cavity closest to the tearable portion and perpendicular to the center connection line of the strengthening member.

3. The easily peelable fiber ribbon introducing optical cable according to claim 2, characterized in that, The normal line direction of the tearable portion is between the tangent line of the strengthening member passing through the vertex of the rectangular inner cavity closest to the tearable portion and the angular bisector of the vertex angle of the rectangular inner cavity closest to it.

4. The easily peelable fiber ribbon introducing optical cable according to claim 3, characterized in that, The normal line direction of the tearable portion and the angular bisector of the vertex angle of the rectangular inner cavity closest to it are on the same straight line.

5. The easily peelable fiber ribbon introducing optical cable according to claim 1, characterized in that, The length t of the tearable portion in the normal line direction accounts for more than 60% of the sheath thickness T in the normal line direction of the tearable portion.

6. The easily peelable fiber ribbon introducing optical cable according to claim 1, characterized in that, The cross-section of the tearable portion is strip-shaped, and it has an opening on the edge of the outer sheath.

7. The easily peelable fiber ribbon introducing optical cable according to claim 5, characterized in that, The opening of the tearable portion on the sheath edge is linear.

8. The easily peelable fiber ribbon introducing optical cable according to claim 5, characterized in that, The tearable portion has a cross-section that narrows bidirectionally on the vertex side close to the rectangular inner cavity and the outer side close to the sheath edge.

9. The easily peelable fiber ribbon introducing optical cable according to claim 1, characterized in that, The peeling force between the first phase and the second phase is in the range of 5 to 50 N; the first phase is made of HDPE, MDPE or LDPE material; the second phase is formed of a tearable material; the elongation at break of the second phase is 10 to 100%, and the tensile strength is 5 to 20 MPa.

10. The easily peelable fiber ribbon introducing optical cable according to claim 9, characterized in that, The formulation of the second-phase material contains, by mass percentage: cycloolefin copolymer: 20%-50%, low-density polyethylene: 25%-50%, linear low-density polyethylene: 15%-30%; the density of the cycloolefin copolymer is 1.010-1.050 kg / m 3 , and the physical property melt index is 1.3-2.0 g / 10 min.

11. A method for preparing the easily peelable fiber ribbon introducing optical cable according to any one of claims 1 to 10, characterized in that, Including the following steps: Using a coextrusion head with a preset rectangular center hole and through holes for the strengthening members on both sides, the coextrusion head has a die cover, and the die cover has a first-phase material outlet and a second-phase material outlet at preset positions respectively. Let the cable core composed of an optical fiber ribbon array pass through the rectangular center hole, and the strengthening members pass through the through holes for the strengthening members on both sides. Extrude the first-phase material and the second-phase material simultaneously outside the cable core and the strengthening members, so that the second-phase material is distributed at a preset position inside the first-phase material. After the first-phase material and the second-phase material are cured, the optical fiber ribbon entry optical cable is obtained.

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