A rat-proof optical cable with a color-strip composite outer sheath and its preparation method

Abstract

The invention discloses a rat-proof optical cable with a composite outer sheath having color stripes and a preparation method thereof. The rat-proof optical cable comprises a composite outer sheath comprising a tightly integrated inner PE sheath, an outer nylon sheath, and an outer nylon color stripe. The composite outer sheath is formed in one step by a three-layer co-extrusion process. The PE material forming the inner PE sheath contains maleic anhydride, wherein the mass ratio of maleic anhydride to PE is 18-20:80-82. The nylon material forming the outer nylon sheath is black nylon 12 material. The nylon material forming the outer nylon color stripe is nylon 12 material containing a preset proportion of masterbatch. The present invention provides a method for preparing a rat-proof optical cable with a composite outer sheath having color stripes. The sheath is formed in one step by a three-layer co-extrusion process. During production, maleic anhydride is added to the PE material of the inner sheath, so that the inner PE sheath and the outer nylon sheath are not easily delaminated. The color stripes formed by the nylon 12 material containing a preset proportion of masterbatch are not easy to fall off, which can effectively prevent the color strips from falling off, and the cable has both rat-proofing and easy-to-identify properties.

Description

Technical Field

[0001] The present invention belongs to the field of optical cable manufacturing, and more particularly, relates to a rodent-proof optical cable with a color-strip composite outer sheath and a preparation method thereof. Background Art

[0002] With the rapid development of communication technology, the installation of communication optical cables in long-distance pipelines is becoming increasingly common. However, during the use of optical cables, rodents often gnaw on exposed optical cables, which can easily cause physical damage to the cables and damage the outer sheath. There is a risk of the optical cables breaking due to the loss of protection caused by extensive damage to the outer sheath. Existing optical cables are mainly protected against rodents by increasing the mechanical strength of the outer sheath or adding chemical rodent repellents to prevent rodent damage to the cables. Although existing rodent-proof optical cables are also widely used in optical communication lines, cable breaks by rodents still occur frequently. Regular inspection and maintenance of optical cables is an important means to prevent cable breaks by rodents.

[0003] As a protective layer protecting optical cables from various challenging environments, the sheath must possess excellent mechanical properties, environmental resistance, and chemical corrosion resistance. Currently, PE is the most commonly used sheath material, but single-layer sheaths offer limited rodent protection. Existing rodent-proof optical cables typically utilize a composite outer sheath, with an inner PE sheath and an outer nylon sheath. Nylon, with its high strength and toughness, is an ideal outer sheath material for optical cables. It also offers termite and rodent resistance, making it a common choice for rodent-proof cable outer sheaths.

[0004] Currently, in long-distance pipeline projects, rodent-proof optical cables are typically constructed simultaneously with the pipeline and laid in the same trench. Often, multiple cables are laid in the same trench. Outdoor rodent-proof optical cables are typically black, making it difficult to quickly identify the cables in complex environments when they require repair. Currently, colored strips are added to the outer sheath of rodent-proof optical cables to identify the cables. However, due to the inherent incompleteness of the colored strips and their insufficient bonding strength with the sheath, the colored strips frequently fall off after installation. This is particularly true with nylon sheaths, where the colored strips frequently fall off, making it difficult to identify the cables requiring maintenance during maintenance. Therefore, the issue of colored strips falling off on the outer sheath is an urgent issue that needs to be addressed, especially with the commonly used composite outer sheaths, where the colored strips are particularly prone to falling off. Summary of the Invention

[0005] In response to the above defects or improvement needs of the prior art, the present invention provides a rat-proof optical cable with a colored strip composite outer sheath and a preparation method thereof. The purpose is to add maleic anhydride to the PE material forming the inner PE sheath, co-extrude it with the nylon material forming the outer nylon sheath and the nylon 12 material forming the outer nylon colored strip, and extrude PE+nylon+colored strips on the outermost layer of the optical cable to form a composite outer sheath in one step, and the colored strips are fixed on the surface of the outer nylon sheath, thereby solving the technical problem that the colored strips on the surface of the composite outer sheath of the existing rat-proof optical cable are easy to fall off.

[0006] To achieve the above object, according to one aspect of the present invention, a rat-proof optical cable with a color strip composite outer sheath is provided, wherein the rat-proof optical cable has a tightly combined inner PE sheath, an outer nylon sheath, and an outer nylon color strip composite outer sheath;

[0007] The composite outer sheath is formed in one step by a three-layer co-extrusion process;

[0008] The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82;

[0009] The nylon material forming the outer nylon sheath is black nylon 12 material;

[0010] The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

[0011] Preferably, the rat-proof optical cable with a color-strip composite outer sheath has a ratio of maleic anhydride to HDPE of 18:82.

[0012] Preferably, the PE material of the rat-proof optical cable with a color-strip composite outer sheath is high-density polyethylene.

[0013] Preferably, in the rat-proof optical cable with a composite outer sheath of colored stripes, the masterbatch in the nylon material forming the outer nylon colored stripes accounts for 3-4% of the mass of the nylon 12 original color material.

[0014] Preferably, in the rat-proof optical cable with a composite outer sheath with colored stripes, the masterbatch in the nylon material forming the outer nylon colored stripes accounts for 3% of the mass of the nylon 12 original color material.

[0015] Preferably, the rat-proof optical cable with a colored strip composite outer sheath comprises a cable core; the cable core comprises a stranded cable core and a stainless steel belt; the stranded cable core is twisted into a fully dry cable core by a non-metallic central reinforcement and a fully dry casing, and a plurality of optical fibers are arranged in the fully dry casing; the outer layer of the stranded cable core is longitudinally wrapped with a stainless steel belt, and the stainless steel belt is provided with an open cable rope.

[0016] According to another aspect of the present invention, there is also provided a method for preparing the rat-proof optical cable having a composite outer sheath with color stripes as described in the present invention, which comprises the following steps:

[0017] Obtaining a cable core to be sheathed;

[0018] The sheath is formed in one step on the outside of the cable core using a three-layer co-extrusion process;

[0019] The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82;

[0020] The nylon material forming the outer nylon sheath is black nylon 12 material;

[0021] The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

[0022] Preferably, the preparation method of the rat-proof optical cable with a color strip composite outer sheath, wherein the three-layer co-extrusion process adopts a single head connected to three extruders to form the sheath at one time, is as follows:

[0023] (1) The main machine is added with PE material to form the inner PE sheath, and the baking temperature is 70°C. The main machine temperature zone includes 5 temperature zones of the machine barrel and 4 temperature zones of the die head. The processing temperatures of the machine cavity temperature zone from left to right on the extruder temperature control interface are set as: 160 / 180 / 190 / 200 / 210°C, and the processing temperatures of the die head temperature zone from left to right are set as: 220 / 230 / 230 / 230°C;

[0024] (2) The fixed color strip machine is used to add nylon material to form the outer nylon sheath, and the drying temperature is 100°C. The temperature zones of the fixed color strip machine include 5 temperature zones in the machine barrel and 4 temperature zones in the die head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set to 205 / 225 / 225 / 230 / 230°C, and the processing temperatures of the die head temperature zones from left to right are set to 225 / 225 / 220 / 220°C. A mobile auxiliary drying machine is also used to preheat the nylon material, and the drying temperature is 100°C.

[0025] (3) The mobile color strip machine is used to add nylon material to form the outer layer of nylon color strips, and the baking temperature is 70°C. The temperature zones of the mobile color strip machine include 3 temperature zones in the machine barrel and 2 temperature zones in the die head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set to 190 / 200 / 225°C; the processing temperatures of the die head temperature zones from left to right are set to 225 / 225°C, and the baking temperature is 70°C. A special screw for nylon is used, and the screw number is: sm~22201JH220704 01~03.

[0026] Preferably, in the method for preparing the rat-proof optical cable with a color-strip composite outer sheath, the PE material forming the inner PE sheath is HDPE containing maleic anhydride, and the preferred mass ratio is: maleic anhydride:HDPE=18:82.

[0027] Preferably, in the method for preparing the rat-proof optical cable with a composite outer sheath having color stripes, the nylon material forming the outer layer nylon color stripes is calculated by weight, and the ratio of masterbatch to nylon 12 natural color material is 3 to 4:100.

[0028] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0029] The rat-proof optical cable with a composite outer sheath with color stripes provided by the present invention is easy to identify due to the color stripes on the surface of the outer sheath. This allows for quick identification of optical cables requiring repair in complex environments, preventing further gnawing by rats that could cause the optical cables to be bitten and disrupt communications. Maleic anhydride is added to the PE material forming the inner PE sheath, and the material is co-extruded with the nylon material forming the outer nylon sheath and the nylon material forming the outer nylon color stripes. The sheath is molded in one step by strictly controlling the baking and extrusion temperatures. This facilitates the formation of fixed color stripes on the surface of the outer nylon sheath, and prevents the inner PE sheath from delaminating from the outer nylon sheath. The nylon material forming the outer nylon color stripes is a nylon 12 material containing a preset ratio of masterbatch. The nylon 12 original color material is mixed with a preset ratio of nylon 12 masterbatch. This color stripe sample is not easily delaminated from the nylon sheath, further preventing the color stripes from falling off.

[0030] Furthermore, the preparation method provided by the present invention is used to prepare a rat-proof optical cable with a color-strip composite outer sheath. The sheath is formed in one step by a three-layer co-extrusion process, and a one-time formed outer sheath of PE+nylon+color strips is extruded on the outermost layer of the cable core. Especially when the ratio of maleic anhydride to HDPE is 18:82, the inner PE sheath and the outer nylon sheath in the composite outer sheath are not easy to delaminate, and the surface is smooth. It can have the characteristics of air blowing performance, rat-proofing and easy identification, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of the rat-proof optical cable with a colored outer sheath in Example 1;

[0032] Figure 1 1 is the outer nylon color strip, 2 is the nylon outer sheath, 3 is the stainless steel belt, 4 is the optical fiber, 5 is the water-blocking yarn, 6 is the center reinforcement, 7 is the casing water-blocking yarn, 8 is the full dry casing, 9 is the open cable, and 10 is the inner PE sheath;

[0033] Figure 2 Schematic diagram of the outer sheath of the rodent-proof optical cable with a colored outer sheath (left) and the projection measurement result (right) in Example 1;

[0034] Figure 3 This is a physical picture of the rodent-proof optical cable obtained in Example 2;

[0035] Figure 4 It is a qualified test sample of the rat-proof optical cable with a composite outer sheath and colored stripes in Example 1;

[0036] Figure 5 This is a real picture of the composite outer sheath of the rodent-proof optical cable in Example 1 and a sample picture after the torsion test;

[0037] Figure 5 A is a physical picture of the composite outer sheath prepared in Comparative Example 1; Figure 5B is a sample picture of the composite outer sheath prepared in comparative example 1 after the torsion test.

[0038] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 is the outer nylon color strip, 2 is the nylon outer sheath, 3 is the stainless steel belt, 4 is the optical fiber, 5 is the water-blocking yarn, 6 is the central reinforcement, 7 is the sleeve water-blocking yarn, 8 is the full dry sleeve, 9 is the open cable, and 10 is the inner PE sheath. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0040] Through practical observation and experimental exploration, we found that there are two reasons why the colored strips on rodent-proof optical cables tend to fall off after installation: first, delamination between the colored strips and the nylon sheath directly causes the strips to fall off; second, delamination between the PE sheath and the nylon sheath causes the nylon sheath to deform, making it easier for the colored strips to delaminate from the nylon sheath, indirectly causing the strips to fall off. Solving the problem of colored strips falling off on composite outer sheaths is more difficult, requiring consideration of both delamination between the inner and outer sheaths and delamination between the colored strips and the outer nylon sheath.

[0041] The present invention finds that maleic anhydride is added to the PE material forming the inner PE sheath, and the material is co-extruded with the nylon material forming the outer nylon sheath and the nylon material forming the outer nylon color stripe, and the sheath is molded once by strictly controlling the drying material and the extruder temperature in the thermoplastic extrusion process. This can form a firm color stripe on the nylon sheath surface, and the inner PE sheath and the outer nylon sheath are not easy to delaminate. The nylon material forming the outer nylon color stripe is a nylon 12 material containing a preset ratio of masterbatch. Because the nylon 12 original color material is matched with the nylon 12 masterbatch, the nylon color stripe obtained is firm, and a high-strength combined color stripe sheath can be formed. In particular, the composite outer sheath of PE+nylon+color stripe formed in one step by a single-head three-layer co-extrusion process has a smooth outer surface and can have the characteristics of air blowing performance, rodent prevention, and easy identification. In addition, the optical cable sheath layer is molded in one step during production, which can reduce the phenomenon of delamination of the inner and outer sheaths of the composite outer sheath, and can also greatly improve production efficiency.

[0042] The rat-proof optical cable with a color strip composite outer sheath provided by the present invention comprises a composite outer sheath formed by tightly combining an inner PE sheath, an outer nylon sheath, and an outer nylon color strip;

[0043] The composite outer sheath is formed in one step by a three-layer co-extrusion process;

[0044] The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82;

[0045] The nylon material forming the outer nylon sheath is black nylon 12 material;

[0046] The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

[0047] During production, maleic anhydride is added to the PE material forming the inner PE sheath, and the sheath is co-extruded with the black nylon 12 material and the nylon material forming the outer nylon color strip to form the sheath, forming color stripes on the surface of the outer nylon sheath.

[0048] By co-extruding a PE material containing maleic anhydride and a nylon material, the inner PE sheath and the outer nylon sheath are tightly bonded, which can significantly improve the bonding strength between the two, avoid the shedding of delaminated color strips, and also help improve production efficiency; according to the mass ratio, the maleic anhydride:PE material = 18-20:80-82, preferably PE is high-density polyethylene (HDPE), HDPE is conducive to improving rodent-proof performance; more preferably maleic anhydride:HDPE = 18:82, in the composite outer sheath obtained by adopting this ratio, the inner PE sheath and the outer nylon sheath are not delaminated and the surface is smooth, which is conducive to ensuring air-blowing performance.

[0049] The nylon material that forms the outer layer nylon color strip is nylon 12 original color material with a preset proportion of masterbatch, that is, color strip nylon 12 material; the sample color strips using these two nylon material ratios are intact and qualified for torsion (outer layer nylon 12 material with color strip nylon 12 material sample, nylon layer 0.46mm~0.54mm wall thickness, 250N counterweight, 1 meter cable sample, torsion angle 180 degrees, 40 times of torsion without cracking of the color strip), while other ratios such as outer layer nylon 6 material with color strip nylon 6 material, outer layer nylon 6 material with color strip nylon 12 material, and outer layer nylon 12 material with color strip nylon 6 material all have stratification phenomena at the color strips.

[0050] The preset ratio is that the masterbatch accounts for 3% to 4% of the mass of the nylon 12 color material, among which the masterbatch is mainly used to adjust the color of the color strip and can be selected according to needs. The masterbatch with strong UV protection is preferred. In addition, the addition amount of the masterbatch needs to be controlled within an appropriate range. This is mainly because if the amount of masterbatch added is too little, the color will be too light and cannot serve as an identification function. If the amount added is too much, the color will be too bright, and the UV protection effect will be poor, which will easily affect the communication effect of the optical cable.

[0051] Furthermore, the rodent-proof optical cable further comprises a cable core and a stainless steel belt; the cable core is preferably a fully dry cable core formed by twisting a non-metallic central reinforcement member and a fully dry casing, and a plurality of optical fibers are arranged in the fully dry casing; using the non-metallic central reinforcement member and the fully dry casing to twist the cable core can reduce the cable weight in terms of material and structure, and ensure the air-blowing performance;

[0052] The stainless steel belt is provided with an open cable rope, and is wrapped around the cable core. Interface parts of the stainless steel belt are overlapped with each other, and the outer layer of the stainless steel belt is extruded with a composite outer sheath.

[0053] In addition, the present invention also provides a method for preparing the rat-proof optical cable with a composite outer sheath having color stripes as described in the present invention, which comprises the following steps:

[0054] Obtaining a cable core to be sheathed;

[0055] The sheath is formed in one step on the outside of the cable core using a three-layer co-extrusion process;

[0056] The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82;

[0057] The nylon material forming the outer nylon sheath is black nylon 12 material;

[0058] The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

[0059] The PE material containing maleic anhydride is co-extruded with the nylon material forming the outer nylon sheath and the nylon material forming the outer nylon color strip, so that the PE sheath layer and the nylon sheath layer are tightly combined without delamination and color strips are formed on the surface of the nylon sheath layer, that is, a composite outer sheath formed by extruding PE+nylon+color strips in one step on the outermost layer of the cable core, thereby obtaining a rat-proof optical cable with a color strip composite outer sheath.

[0060] The nylon material forming the outer nylon sheath is black nylon 12. Generally speaking, although masterbatches are added to color strips to obtain different markings, the sheath material and the color strips will use the same matrix material to improve the bonding ability of the color strips. However, once the masterbatch is added to the nylon sheath material, the bonding strength of the nylon material is seriously affected. Practice has found that the bonding degree of nylon 6, which is commonly used in optical cable production, is sensitive to the masterbatch. After adding the masterbatch, the bonding ability of the co-extruded sheath decreases, and the color strips are easy to fall off; the bonding between nylon sheaths and nylon color strips with different matrices is even more difficult to meet the requirements for the bonding strength of the color strips. However, after adding the masterbatch, nylon 12 can form a color strip that is firmly bonded to the sheath, meeting the use requirements. That is, the nylon material forming the outer nylon color strips in the present invention is nylon 12 original color material with nylon 12 masterbatch.

[0061] The PE material containing maleic anhydride has a mass ratio of maleic anhydride:PE material = 18-20:80-82; the PE material is preferably high-density polyethylene (HDPE), which is beneficial to improving the rodent-proof performance, and more preferably maleic anhydride:HDPE = 18:82. The inner PE sheath and the outer nylon sheath are not easy to delaminate and have a smooth surface, which is beneficial to preventing the color strips from falling off.

[0062] The experimental results show that when the mass fraction of maleic anhydride exceeds 20%, the inner layer of HDPE and the outer layer are not separated, but the surface is rough, such as Figure 3 As shown in the figure, the excessive amount of maleic anhydride may cause the PE material to shrink unstable; when the ratio of maleic anhydride to HDPE is 18:82, the inner layer of HDPE and the outer layer of nylon are not separated and the surface is smooth. Figure 4 As shown; When maleic anhydride:HDPE=16:84, the inner layer HDPE and the outer layer nylon material are not tightly bonded. Figure 5 As shown in Figure A, the use of maleic anhydride will significantly affect the bonding between the PE layer and the nylon sheath, and by affecting the curing shrinkage of the nylon layer, it will ultimately affect the bonding strength of the color strips. The results of the sheath torsion test are shown in Figure Figure 5 As shown in B, it is shown that the amount of maleic anhydride added must be controlled within an appropriate range, and improper use of maleic anhydride will easily lead to stratification.

[0063] However, the addition of maleic anhydride also brings difficulties to the process implementation. Compared with ordinary PE materials, PE materials containing maleic anhydride are more prone to accumulation and solidification clogging of the extruder head due to the influence of nylon temperature when co-extruded with nylon 12, which has a higher extrusion operating temperature. Even if the extruder head is not blocked, partial solidification can cause uncontrollable shrinkage of the sheath, affecting the adhesion of the color stripe. Through repeated practice, it was found that by precisely controlling the extrusion operating temperature and the temperature of each stage of the extruder, the maleic anhydride PE material and nylon 12 are in a good flow state and the real-time solidification shrinkage is comparable, which can ensure a good bonding between the PE layer and the nylon layer.

[0064] Furthermore, the three-layer co-extrusion process uses a single head to connect three extruders to form the sheath at one time, specifically as follows:

[0065] (1) The main machine is a single-thread BM screw extruder with 9 temperature zones, which is used to add maleic anhydride PE material to form the inner PE sheath, and the drying temperature is 70°C; the 9 temperature zones include 5 temperature zones in the machine barrel and 4 temperature zones in the die head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set to 160 / 180 / 190 / 200 / 210 (unit: °C), and the processing temperatures of the die head temperature zones from left to right are set to 220 / 230 / 230 / 230 (unit: °C);

[0066] Wherein, by mass ratio, maleic anhydride:PE=18-20:80-82, preferably, PE is high-density polyethylene, more preferably maleic anhydride:HDPE=18:82;

[0067] (2) The fixed color strip machine is a single-thread BM screw extruder with 9 temperature zones, which is used to add black nylon 12 to form the outer nylon sheath. The black nylon 12 is a mixture of nylon 12 black masterbatch and nylon 12 original color material prepared in a preset proportion and mixed evenly; the drying temperature is 100°C, and the 9 temperature zones include 5 temperature zones in the machine barrel and 4 temperature zones in the machine head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set to: 205 / 225 / 225 / 230 / 230 (unit: °C), and the processing temperatures of the machine head temperature zones from left to right are set to 225 / 225 / 220 / 220 (unit: °C); a mobile auxiliary drying machine is used to assist in drying the material, and the drying temperature is 100°C to preheat the nylon material and at the same time play a moisture-proof role.

[0068] (3) The mobile color strip machine is a single-thread BM screw extruder with 5 temperature zones, which is used to add nylon material to form the outer layer of nylon color strips. The nylon material to form the outer layer of nylon color strips is prepared by uniformly mixing nylon 12 masterbatch and nylon 12 original color material in a preset ratio. The masterbatch in the color strips is selected according to the needs of the appropriate color; the preset ratio is 3% to 4% of the mass of nylon 12 masterbatch to nylon 12 original color material;

[0069] The five temperature zones include three temperature zones in the barrel and two temperature zones in the die head. The processing temperatures of the cavity temperature zones on the extruder temperature control interface are set to 190 / 200 / 225°C from left to right; the processing temperatures of the die head temperature zones are set to 225 / 225°C from left to right, and the baking temperature is 70°C.

[0070] The color stripe nylon extruder uses a dedicated nylon screw, screw number: sm-22201JH22070401-03. This is because the amount of nylon material used to form the outer layer of nylon color stripe is small, and the nylon material has high viscosity, which easily entangles the screw, causing the screw to stall and cause color breakage. Using a dedicated nylon screw can increase the screw thrust, making it less likely to accumulate material inside the screw, thus avoiding screw stalls and color breakage.

[0071] The experimental results show that the outer layer nylon 6 material with color strip nylon 6 material, the outer layer nylon 6 material with color strip nylon 12 material, and the outer layer nylon 12 material with color strip nylon 6 material all have delamination phenomena at the color strip, while the outer layer nylon 12 material with color strip nylon 12 material samples have intact color strips and are qualified after torsion.

[0072] The torsion test results show that the outer layer of nylon 12 material with color strip nylon 12 material sample, nylon layer 0.46mm ~ 0.54mm wall thickness, 250N counterweight, 1 meter cable sample, torsion angle 180 degrees, torsion 40 times without cracking of the color strip, such as Figure 4 shown.

[0073] A three-layer co-extrusion process is adopted to co-extrude the PE material forming the inner PE sheath, the nylon material forming the outer nylon sheath and the nylon material forming the outer nylon color strip, and a composite outer sheath of PE+nylon+color strip formed in one step is extruded on the outermost layer of the cable core component to obtain a rat-proof optical cable with a color strip composite outer sheath.

[0074] Preferably, high-density polyethylene (HDPE) containing maleic anhydride is co-extruded with the above-mentioned nylon material and formed in one step using a single head. In the present invention, a single head is used to connect three extruders for one-step forming, which can improve production efficiency, reduce optical cable diameter, and effectively solve the problem of high defective rate in the production of single-layer nylon material.

[0075] Furthermore, the cable core to be sheathed is obtained according to the following steps:

[0076] The central reinforcement and the full-dry casing are twisted into a full-dry cable core, and multiple optical fibers are arranged in the full-dry casing;

[0077] The fully dry cable core is longitudinally wrapped with stainless steel tape, and the interface parts of the stainless steel tape are overlapped with each other;

[0078] Two twisted aramid open ropes are added symmetrically 180 degrees to the stainless steel belt to obtain the cable core to be sheathed.

[0079] The central reinforcement is preferably a non-metallic central reinforcement. The non-metallic central reinforcement and the fully dry casing are twisted into a cable core, which can reduce the cable weight in terms of material and structure and ensure the air blowing performance.

[0080] The following are examples:

[0081] Example 1: Rat-proof optical cable with a color-strip composite outer sheath

[0082] The rat-proof optical cable with a color strip composite outer sheath is as follows: Figure 1 As shown, it includes a cable core, a stainless steel belt, an open cable rope and a composite outer sheath; a plurality of optical fibers are arranged in the cable core, a stainless steel belt is wrapped around the cable core, the interface parts of the stainless steel belt are overlapped with each other, and a composite outer sheath is extruded on the outer layer of the stainless steel belt; the composite outer sheath is a PE+nylon+color strip one-piece molded sheath, the inner layer of the composite outer sheath is a PE sheath, the outer layer is a nylon sheath, and the color strips are arranged on the surface of the nylon sheath;

[0083] The rat-proof optical cable with a color strip composite outer sheath is obtained specifically according to the following preparation method:

[0084] The central reinforcement is twisted with the full-dry casing to form a full-dry cable core, and multiple optical fibers are arranged in the full-dry casing;

[0085] The obtained stranded cable core is longitudinally wrapped with stainless steel tape, the interface parts are overlapped together, and two twisted aramid open cables are added at 180 degrees symmetry;

[0086] Using a single head, full-color diverter cone, color stripe mold cover and other extrusion molds, the sheath is formed in one step using a three-layer co-extrusion process to obtain a rodent-proof optical cable with a color stripe composite outer sheath;

[0087] The three-layer co-extrusion process is specifically as follows:

[0088] (1) The main machine is a single-thread BM screw extruder with 9 temperature zones, which is used to add maleic anhydride PE material to form the inner PE sheath. The drying temperature is 70°C. The 9 temperature zones include 5 temperature zones in the machine barrel and 4 temperature zones in the die head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set as: 160 / 180 / 190 / 200 / 210 (unit: °C), and the processing temperatures of the die head temperature zones from left to right are set as: 220 / 230 / 230 / 230 (unit: °C);

[0089] Wherein PE is high-density polyethylene, maleic anhydride:HDPE=18:82;

[0090] (2) The fixed color strip machine is a single-thread BM screw extruder with 9 temperature zones, which is used to add black nylon 12 to form an outer nylon sheath. The black nylon 12 is prepared according to the nylon 12 black masterbatch accounting for 3% of the mass of the nylon 12 original color material, and the black nylon 12 is obtained by uniform mixing; the 9 temperature zones include 5 temperature zones in the machine barrel and 4 temperature zones in the head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set as: 205 / 225 / 225 / 230 / 230 (unit: °C), and the processing temperatures of the head temperature zones from left to right are set as 225 / 225 / 220 / 220 (unit: °C), and the drying temperature is 100 °C; a mobile auxiliary drying machine is added to assist in drying the material. The auxiliary drying machine is equipped with a material extraction device, which first extracts the nylon material into the extruder hopper for drying for 2 hours and then extracts it into the extruder hopper. The auxiliary drying temperature is 100 °C.

[0091] (3) The mobile color strip machine is a single-thread BM screw extruder with 5 temperature zones, which is used to add nylon material to form the outer layer of nylon color strips: the nylon material to form the outer layer of nylon color strips is prepared by uniformly mixing nylon 12 blue masterbatch to obtain blue nylon material;

[0092] The five temperature zones include three temperature zones in the barrel and two temperature zones in the die head. The processing temperatures of the cavity temperature zones on the extruder temperature control interface are set to 190 / 200 / 225°C from left to right; the processing temperatures of the die head temperature zones are set to 225 / 225°C from left to right, and the baking temperature is 70°C.

[0093] Color strip nylon extruder uses nylon special screw, screw number: sm~22201JH22070401~03;

[0094] Color stripes are added to the surface of the sheath; it has a full-color diverter cone with 2 through holes (GQ L=107.8Z~AC~1.5~3 / 9~2TH~11.0*2). There are two through holes at 3 / 9. When installing, the through holes on the left and right sides correspond to the 3 o'clock and 9 o'clock directions respectively.

[0095] The end face of the mold cover is installed flush with the end face of the large platform of the diverter; from left to right on the production line: the mold cover color strip inlet is aligned with the 9-point through-hole on the diverter; from right to left on the production line: the mold cover color strip inlet is aligned with the 3-point through-hole on the diverter; two layers of 60 filter screens are used on the filter screens of the two color strip machines;

[0096] Before starting the machine, turn on the fixed color strip machine, discharge the nylon material first and then the HDPE material; when debugging the sample, turn off the fixed color strip machine first, measure the inner layer diameter, then turn on the fixed color strip machine, measure the total diameter, and subtract the two diameters to get the nylon layer thickness, such as Figure 2 As shown in (left), the accurate thickness of the nylon layer is measured by instrument projection after slicing, such as Figure 2 (right) shown.

[0097] Example 2: Rat-proof optical cable with a color-strip composite outer sheath

[0098] The rat-proof optical cable is the same as that described in Example 1, and is specifically prepared according to the following preparation method:

[0099] Except that the host uses HDPE containing maleic anhydride, maleic anhydride:HDPE=20:80, the rest is the same as in Example 1, and the obtained rat-proof optical cable is as follows Figure 3 shown.

[0100] Depend on Figure 3 It can be seen that when the ratio of maleic anhydride to HDPE is 20:80, the inner layer of HDPE and the outer layer of nylon are not separated.

[0101] Example 3: Test on the color strip fastness of the rat-proof optical cable with a color strip outer sheath

[0102] The rat-proof optical cable with a color strip composite outer sheath obtained in Example 1 was subjected to a torsion test. The results showed that the outer nylon sheath was made of nylon 12 material with color strip nylon 12 material, the nylon layer wall thickness was 0.46mm-0.54mm, the counterweight was 250N, the cable sample was 1 meter, the torsion angle was 180 degrees, and the color strip was not cracked after 40 twists. Figure 4 shown.

[0103] Comparative Example 1: Rat-proof Optical Cable

[0104] The rat-proof optical cable is the same as that described in Example 1, and is specifically prepared according to the following preparation method:

[0105] Except that HDPE containing maleic anhydride is added to the host, maleic anhydride:HDPE=16:84, the rest is the same as in Example 1, and the obtained rat-proof optical cable is as follows Figure 5 shown.

[0106] Depend on Figure 5 A shows that when maleic anhydride:HDPE=16:84, the inner layer HDPE and the outer layer nylon material are not tightly bonded, and obvious gaps can be seen; Figure 5 The results of the B sheath torsion test show that the sheath is prone to delamination, which can easily cause the color strips to fall off, and cannot serve as an identification function when the optical cable needs maintenance.

[0107] Comparative Example 2: Rat-proof Optical Cable

[0108] The rat-proof optical cable is the same as that described in Example 1, and is specifically prepared according to the following preparation method:

[0109] Except that the nylon material forming the outer layer nylon color strip is nylon 6 material with color strip nylon 6 material, other aspects are the same as in Example 1. The obtained rat-proof optical cable has delamination phenomenon at the color strip.

[0110] Comparative Example 3: Rat-proof Optical Cable

[0111] The rat-proof optical cable is the same as that described in Example 1, and is specifically prepared according to the following preparation method:

[0112] Except that the nylon material forming the outer layer nylon color strip is nylon 6 material and nylon 12 material for the color strip, other aspects are the same as in Example 1. The obtained rat-proof optical cable has a delamination phenomenon at the color strip.

[0113] Comparative Example 4: Rat-proof Optical Cable

[0114] The rat-proof optical cable is the same as that described in Example 1, and is specifically prepared according to the following preparation method:

[0115] Except that the nylon material forming the outer layer nylon color strip is nylon 12 material and nylon 6 material for the color strip, other aspects are the same as in Example 1. The obtained rat-proof optical cable has delamination at the color strip.

[0116] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rodent-proof optical cable with a color strip composite outer sheath, characterized in that: It has a tightly combined inner PE sheath, outer nylon sheath, and outer nylon color strip composite outer sheath; The composite outer sheath is formed in one step by a three-layer co-extrusion process; The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82; The nylon material forming the outer nylon sheath is black nylon 12 material; The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

2. The rat-proof optical cable with a color strip composite outer sheath according to claim 1, characterized in that: Maleic anhydride:HDPE=18:

82.

3. The rodent-proof optical cable with a color strip composite outer sheath according to claim 1 or 2, characterized in that: The PE material is high-density polyethylene.

4. The rodent-proof optical cable with a color strip composite outer sheath according to claim 1, characterized in that: In the nylon material forming the outer layer nylon color strip, the color masterbatch accounts for 3-4% of the mass of the nylon 12 original color material.

5. The rodent-proof optical cable with a color strip composite outer sheath according to claim 4, characterized in that: In the nylon material forming the outer layer nylon color strip, the color masterbatch accounts for 3% of the mass of the nylon 12 original color material.

6. The rat-proof optical cable with a color strip composite outer sheath according to claim 1, characterized in that: It also includes a cable core; the cable core includes a stranded cable core and a stainless steel belt; the stranded cable core is twisted into a fully dry cable core by a non-metallic central reinforcement and a fully dry casing, and a plurality of optical fibers are arranged in the fully dry casing; the outer layer of the stranded cable core is longitudinally wrapped with a stainless steel belt, and the stainless steel belt is provided with an open cable rope.

7. A method for preparing a rodent-proof optical cable having a color strip composite outer sheath according to any one of claims 1 to 6, characterized in that: The following steps are involved: Obtaining a cable core to be sheathed; The sheath is formed in one step on the outside of the cable core using a three-layer co-extrusion process; The PE material forming the inner PE sheath contains maleic anhydride; wherein the mass ratio is: maleic anhydride:PE=18-20:80-82; The nylon material forming the outer nylon sheath is black nylon 12 material; The nylon material forming the outer layer nylon color strip is nylon 12 material containing a preset proportion of masterbatch.

8. The method for preparing a rodent-proof optical cable with a color strip composite outer sheath according to claim 7, characterized in that: The three-layer co-extrusion process uses a single head to connect three extruders to form the sheath at one time, as follows: (1) The main machine is added with PE material to form the inner PE sheath, and the baking temperature is 70°C. The main machine temperature zone includes 5 temperature zones of the machine barrel and 4 temperature zones of the die head. The processing temperatures of the machine cavity temperature zone from left to right on the extruder temperature control interface are set as: 160 / 180 / 190 / 200 / 210°C, and the processing temperatures of the die head temperature zone from left to right are set as: 220 / 230 / 230 / 230°C; (2) The fixed color strip machine is used to add nylon material to form the outer nylon sheath, and the drying temperature is 100°C. The temperature zones of the fixed color strip machine include 5 temperature zones in the machine barrel and 4 temperature zones in the die head. The processing temperatures of the machine cavity temperature zones from left to right on the extruder temperature control interface are set to 205 / 225 / 225 / 230 / 230°C, and the processing temperatures of the die head temperature zones from left to right are set to 225 / 225 / 220 / 220°C. A mobile auxiliary drying machine is also used to preheat the nylon material, and the drying temperature is 100°C. (3) The mobile color strip machine is used to add nylon material to form the outer layer of nylon color strips, and the baking temperature is 70°C. The temperature zones of the mobile color strip machine include 3 temperature zones in the machine barrel and 2 temperature zones in the machine head. The processing temperatures of the machine cavity temperature zones from left to right in the extruder temperature control interface are set to 190 / 200 / 225°C; the processing temperatures of the machine head temperature zones from left to right are set to 225 / 225°C, and the baking temperature is 70°C. A special screw for nylon is used, and the screw number is: sm~22201JH22070401~03.

9. The method for preparing a rodent-proof optical cable with a color strip composite outer sheath according to claim 7, wherein: The PE material forming the inner PE sheath is HDPE containing maleic anhydride, and the mass ratio is: maleic anhydride:HDPE=18:

82.

10. The method for preparing a rodent-proof optical cable with a color strip composite outer sheath according to claim 7, wherein: The nylon material forming the outer layer nylon color strip is calculated based on the mass fraction, and the ratio of masterbatch to nylon 12 natural color material is 3 to 4:100.

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