B1-grade flame-retardant sheath with d0-grade combustion drippings, preparation method of B1-grade flame-retardant sheath and application of B1-grade flame-retardant sheath in optical cable

Abstract

The invention provides a B1-level flame-retardant sheath with a d0-level combustion dripping level, a preparation method of the B1-level flame-retardant sheath and an application of the B1-level flame-retardant sheath in an optical cable. The B1-grade flame-retardant protective material sleeve comprises the following components in percentage by mass: 15-19% of ethylene-vinyl acetate copolymer; 5.5%-8.5% of linear low density polyethylene; 2%-4% of an ethylene-octylene copolymer; 2%-5% of a compatilizer; 1%-1.6% of black color master batch; 60%-71.5% of aluminum hydroxide; 0.3%-0.5% of red phosphorus; 2%-3% of a charring agent; 1.3%-1.5% of a lubricant; and 0.2%-0.3% of an antioxidant. The B1-level flame-retardant protective material sleeve with the d0-level combustion dripping level has lower total heat release and heat release rate, has high oxygen index and ignition time, is better in flame retardant property, and facilitates B1-level flame retardance of cabling.

Description

Technical Field

[0001] This invention belongs to the field of optical cable technology, and in particular relates to a B1-grade flame-retardant sheath with a combustion droplet level of d0, its preparation method, and its application in optical cables. Background Technology

[0002] According to China Fire Protection Network, electrical fires rank first among all types of fires, accounting for 50% of all fires with identified causes. Electrical fires pose a significant threat to society. Regulations and standards worldwide stipulate the flammability of cables. The EU's Building Products Regulation (305 / 2011 / EU-CPR) mandates that power, control, and communication cables and optical fibers must meet the EN50575-2014+A1:2016 standard. my country has also promulgated and implemented GB31247—2014 "Classification of Flammability of Cables and Optical Fibers," making flame-retardant properties an essential characteristic for high-rise buildings, subways, airports, train stations, hospitals, schools, and other high-traffic areas. The market demand for cables meeting B1 flame-retardant requirements has increased dramatically. Achieving B1 flame-retardant performance depends not only on cable structural design but, most importantly, on using an outer sheath made of polyolefin material that meets B1 flame-retardant standards. This not only achieves B1 flame retardancy but also meets the d0 rating for burning droplets. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a B1-grade flame-retardant sheath with a combustion dripping level of d0, its preparation method, and its application in optical cables. The B1-grade flame-retardant sheath with a combustion dripping level of d0 is applied to optical cables to meet the market demand for flame-retardant optical cables.

[0004] The technical solution of this invention is:

[0005] The first aspect of this invention provides a B1-grade flame-retardant protective sleeve with a combustion drip level of d0, wherein the B1-grade flame-retardant protective sleeve comprises the following components by weight percentage:

[0006]

[0007]

[0008] The second aspect of the present invention provides a method for preparing a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0. The preparation method includes mixing, kneading, granulating, pelletizing, collecting and packaging ethylene-vinyl acetate copolymer, linear low-density polyethylene, ethylene-octene copolymer, compatibilizer, black masterbatch, aluminum hydroxide, red phosphorus, charring agent, lubricant and antioxidant to produce a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0.

[0009] A third aspect of the present invention provides an optical cable comprising, from the inside out, a semi-dry cable core, an inner sheath, and an outer sheath. The semi-dry cable core comprises, from the inside out, a central reinforcing member, an assembly, and a water-blocking tape. The assembly includes multiple loose tubes evenly distributed along the outer periphery of the central reinforcing member and multiple filler ropes. Each loose tube contains multiple optical fibers, and fiber grease is filled between the optical fibers and the inner wall of the loose tube. The inner sheath comprises, from the inside out, an aluminum-plastic composite tape and an oxygen barrier layer. The aluminum-plastic composite tape is disposed on the side in contact with the water-blocking tape. The oxygen barrier layer is disposed on the side in contact with the outer sheath. The outer sheath includes a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in the first aspect of the present invention and / or a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 prepared by the preparation method described in the second aspect of the present invention.

[0010] By adopting the aforementioned technical solution, the beneficial effects of the present invention are:

[0011] The B1-grade flame-retardant protective sleeve of the present invention, with a combustion dripping grade of d0, has a lower total heat release and heat release rate, and has a high oxygen index and good flame-retardant performance in terms of ignition time, which is beneficial for achieving B1-grade flame retardancy in cabling.

[0012] The optical cable of this invention is a Class B1 flame-retardant optical cable with a combustion dripping level of d0. Specifically, a Class B1 flame-retardant sheath with a combustion dripping level of d0 is applied to the outer sheath layer. The cable is then manufactured into a finished optical cable according to the optical cable structure, and its combustion performance is tested according to the Class B1 requirements of standard GB / T 31247. When the prepared optical cable burns, the outer sheath carbonizes to form a hard and dense shell, which can block the impact of external flames and the expansion of internal combustibles without detachment, achieving a combustion dripping level of d0. Simultaneously, the entire optical cable has a low heat release rate and low calorific value, meeting the Class B1 flame-retardant requirements. Attached Figure Description

[0013] Figure 1 The diagram shows the structure of the optical cable of this invention. 1-Optical fiber, 2-Fiber grease, 3-Loose tube, 4-Central reinforcement, 5-Filling rope, 6-Water-blocking tape, 7-Aluminum-plastic composite tape, 8-Oxygen barrier layer, 9-Steel-plastic composite tape, 10-Outer sheath. Detailed Implementation

[0014] The following details the implementation of a B1-grade flame-retardant sheath with a combustion dripping level of d0 provided by the present invention, its preparation method, and its application in optical cables.

[0015] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0016] [B1-grade flame-retardant protective sleeve with a d0 rating for burning droplets]

[0017] The B1-grade flame-retardant protective sleeve with a combustion drip level of d0 includes ethylene-vinyl acetate copolymer, linear low-density polyethylene, ethylene-octene copolymer, compatibilizer, black masterbatch, aluminum hydroxide, red phosphorus, charring agent, lubricant, and antioxidant.

[0018] The B1-grade flame-retardant protective sleeve comprises, by weight percentage, 15%–19% ethylene-vinyl acetate copolymer. Optionally, the weight percentage of ethylene-vinyl acetate copolymer may also be 15%–16%, 16%–17%, 17%–18%, or 18%–19%. The density of the ethylene-vinyl acetate copolymer is 0.92–0.98 g / cm³. 3 The melt flow index is 2–4 g / 10 min. Optionally, the density of the ethylene-vinyl acetate copolymer can be 0.92–0.94 g / cm³. 3 Or 0.94~0.98g / cm 3 The melt flow index can be 2–2.5 g / 10 min, 3.0–3.5 g / 10 min, or 3.5–4.0 g / 10 min.

[0019] The B1-grade flame-retardant protective sleeve comprises, by weight percentage, 5.5% to 8.5% linear low-density polyethylene. Optionally, the weight percentage of linear low-density polyethylene can be 5.5% to 6.5%, 6.5% to 7.5%, or 7.5% to 8.5%. The density of the linear low-density polyethylene is 0.92 to 0.96 g / cm³. 3 The melt flow index is 0.2–0.5 g / 10 min. Optionally, the density of linear low-density polyethylene can be 0.92–0.94 g / cm³. 3 0.94~0.96g / cm 3 The melt index can be 0.2~0.25g / 10min, 0.25~0.3g / 10min, 0.3~0.35g / 10min, 0.35~0.4g / 10min, 0.4~0.45g / 10min, or 0.45~0.5g / 10min.

[0020] The B1-grade flame-retardant protective sleeve comprises, by weight percentage, 2% to 4% ethylene-octene copolymer; optionally, the weight percentage of ethylene-octene copolymer can be 2% to 3% or 3% to 4%. The density of the ethylene-octene copolymer is 0.8 to 0.92 g / cm³. 3 The melt flow index is 2–4 g / 10 min. The density of the ethylene-octene copolymer can be 0.8–0.86 g / cm³. 3 0.8~0.92g / cm 3 The melt flow index can be 2-2.5 g / 10 min, 2.5-3 g / 10 min, 3-3.5 g / 10 min, or 3.5-4 g / 10 min.

[0021] The B1-grade flame-retardant protective sleeve comprises 2% to 5% compatibilizer by weight percentage. Optionally, the compatibilizer, polyvinyl alcohol, may have a weight percentage of 2% to 2.5%, 2.5% to 3%, 3.5% to 4%, or 4.5% to 5%. The compatibilizer is polyvinyl alcohol with a degree of hydrolysis of 86% to 89%. Optionally, the degree of hydrolysis may be 86% to 87%, 87% to 88%, or 88% to 89%.

[0022] The B1-grade flame-retardant protective sleeve comprises, by weight percentage, 1% to 1.6% black masterbatch; optionally, the weight percentage of black masterbatch can be 1% to 1.3% or 1.3% to 1.6%. The black masterbatch is polyethylene with added carbon black, and has a density of 1.10 to 1.15 g / cm³. 3 The melt flow index is 10–20 g / 10 min. Optionally, the density can be 1.10–1.12 g / cm³. 3 1.12~1.15g / cm 3 1.10~1.13g / cm3 1.13~1.15g / cm 3 The melt flow index can be 10-12 g / 10 min, 12-14 g / 10 min, 14-16 g / 10 min, 16-18 g / 10 min, or 18-20 g / 10 min.

[0023] The B1-grade flame-retardant protective sleeve comprises 60%–71.5% aluminum hydroxide by weight. Optionally, the mass percentage of aluminum hydroxide can be 60%–62%, 62%–64%, 64%–66%, 66%–68%, 68%–70%, or 70%–71.5%. The particle size of the aluminum hydroxide is 1–4 μm, and optionally, the particle size can be 1–1.5 μm, 1.5–2 μm, 2.5–3 μm, 3–3.5 μm, or 3.5–4 μm.

[0024] The B1 grade flame-retardant protective sleeve includes 0.3% to 0.5% red phosphorus by weight percentage. Optionally, the weight percentage of red phosphorus can be 0.3% to 0.35%, 0.35% to 0.4%, 0.4% to 0.5%, or 0.45% to 0.5%. The red phosphorus particle size is 2 to 5 μm. Optionally, the red phosphorus particle size can be 2 to 2.5 μm, 2.5 to 3 μm, 3 to 3.5 μm, 3.5 to 4 μm, 4 to 4.5 μm, or 4.5 to 5 μm.

[0025] In some embodiments, the mass ratio of aluminum hydroxide to red phosphorus is 60:0.5 to 70:0.5. The mass ratio of aluminum hydroxide to red phosphorus can be 65:0.5 to 70:0.5, or 60:0.5 to 65:0.5.

[0026] The B1-grade flame-retardant protective sleeve includes 2%–3% charring agent by weight percentage. Optionally, the weight percentage of the charring agent can be 2.2%–2.4%, 2.4%–2.6%, 2.6%–2.8%, or 2.8%–3%. The charring agent is a mixture of nano-modified montmorillonite, nano-alumina, and nano-magnesium oxide. The nano-modified montmorillonite is modified with an organic ammonium salt, and the modification method can refer to commonly used modification methods in this technical field. The nano-alumina particle size is 20–120 nm. Optionally, the nano-alumina particle size can be 20–30 nm, 30–40 nm, 40–50 nm, 50–60 nm, 60–70 nm, 70–80 nm, 80–90 nm, 90–100 nm, 100–110 nm, or 110–120 nm. The nano zinc oxide particles have a diameter of 20–80 nm. Optionally, the nano magnesium oxide particles have a diameter of 20–30 nm, 30–40 nm, 40–50 nm, 50–60 nm, 60–70 nm, or 70–80 nm.

[0027] The B1-grade flame-retardant protective sleeve includes 1.3% to 1.5% lubricant by weight percentage; optionally, the lubricant weight percentage can be 1.3% to 1.4% or 1.4% to 1.5%. The lubricant is dimethyl silicone oil.

[0028] The B1-grade flame-retardant protective sleeve includes 0.2% to 0.3% antioxidant by weight percentage. Optionally, the antioxidant by weight percentage can be 0.2% to 0.25% or 0.25% to 0.3%. The antioxidant is selected from a combination of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-hydroxyphenyl)propionate) (antioxidant 1010) and disodium thiodipropionate (antioxidant DLTP).

[0029] Lubricants and antioxidants together constitute processing aids. The ratio of dimethyl silicone oil, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-hydroxyphenyl)propionate) to dodecanol thiodipropionate is 3:1:1 to 5:1:1, and optionally, the mass ratio can be 4:1:1 to 5:1:1 or 3:1:1 to 4:1:1.

[0030] [Preparation method of B1 grade flame-retardant protective sleeve with a combustion dripping grade of d0]

[0031] The present invention also provides a method for preparing a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in the first aspect of the present invention. The preparation method includes mixing, kneading, granulating, pelletizing, collecting and packaging ethylene-vinyl acetate copolymer, linear low-density polyethylene, ethylene-octene copolymer, compatibilizer, black masterbatch, aluminum hydroxide, red phosphorus, charring agent, lubricant and antioxidant to produce a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0.

[0032] The dosage and specific selection of each component are as described in the first aspect of this invention.

[0033] Through systematic testing, the prepared B1-grade sheath material with a combustion dripping grade of d0 provides reliable flame retardancy for optical cables, meeting the requirements of B1 and d0 dripping.

[0034] Fiber optic cable

[0035] like Figure 1 This application provides an optical cable, which includes a semi-dry cable core, an inner sheath, and an outer sheath layer from the inside out.

[0036] Semi-dry cable core

[0037] In the optical cable provided by the present invention, the semi-dry cable core includes, from the inside out, a central reinforcing member 4, an assembly and a water-blocking tape 6. The assembly includes a plurality of loose tubes 3 and a plurality of filler ropes 5 evenly distributed along the outer periphery of the central reinforcing member 4. Each loose tube 3 is provided with a plurality of optical fibers 1, and the space between the optical fibers 1 and the inner wall of the loose tube 3 is filled with fiber grease 2.

[0038] In the optical cable provided by the present invention, the number of optical fibers 1 is 6 to 12.

[0039] In the optical cable provided by the present invention, the fiber paste 2 is a high molecular polymer that serves as a water-blocking agent.

[0040] In the optical cable provided by the present invention, the diameters of the loose tube 3 and the filler rope 5 are both 1.6 to 2.8 mm.

[0041] In the optical cable provided by the present invention, the loose tube 3 is made of polybutylene terephthalate (PBT).

[0042] In the optical cable provided by the present invention, the central reinforcing member 4 is made of phosphated steel wire with a modulus greater than 190GP.

[0043] In the optical cable provided by the present invention, the diameter of the central reinforcing member 4 is 1.7 to 3.5 mm.

[0044] In the optical cable provided by this invention, each of the loose tubes 3 and the filler ropes 5 are twisted together with the central reinforcing member 4. For example, the loose tubes 3 and the filler ropes 5 are tied to the surface of the central reinforcing member 4 in an SZ twisted manner, and the cross-section of the cable core after tying is circular.

[0045] In the optical cable provided by this invention, the filler rope 5 is a low-smoke halogen-free flame-retardant material, such as Wuxi Jieke New Material Co., Ltd., model JK WDZ-2JG1.

[0046] In the optical cable provided by this invention, the thickness of the water-blocking tape 6 is 0.20 mm. For example, the water-blocking tape 6 is made of polyester material, which expands after absorbing water, providing longitudinal water-blocking function for the cable core.

[0047] Inner protective layer

[0048] The inner protective layer comprises, from the inside out, an aluminum-plastic composite strip 7 and an oxygen barrier layer 8. The aluminum-plastic composite strip 7 is located on the side that contacts the water-blocking strip 6; the oxygen barrier layer 8 is located on the side that contacts the outer protective layer.

[0049] In the optical cable provided by this invention, an aluminum-plastic composite tape 7 is longitudinally wrapped around the semi-dry cable core. The thickness of the aluminum-plastic composite tape 7 is 0.25 mm. The coverage rate of the aluminum-plastic composite tape 7 is 20%.

[0050] In the optical cable provided by this invention, the thickness of the oxygen barrier layer 8 is 1.2–1.5 mm. A layer of low-smoke halogen-free polyolefin oxygen barrier material is extruded onto the surface of the aluminum strip to form the oxygen barrier layer 8. When the oxygen barrier material burns, it forms a crust covering the surface of the aluminum strip, isolating the cable core from external oxygen and preventing the intrusion of external flames. The low-smoke halogen-free polyolefin oxygen barrier material is manufactured by Shanghai Kete, and the model is 0.20*20mm.

[0051] <Outer Sheath>

[0052] In the optical cable provided by the present invention, the outer sheath layer includes, from the inside to the outside, a steel-plastic composite strip 9 and an outer sheath 10, wherein the steel-plastic composite strip 9 is disposed on the side in contact with the oxygen barrier layer 8.

[0053] In the optical cable provided by the present invention, the thickness of the steel-plastic composite tape 9 is 0.25mm.

[0054] In the optical cable provided by this invention, the thickness of the outer sheath 10 is 1.8–2.2 mm. The material of the outer sheath 10 is a B1-grade sheath material with a combustion droplet rating of d0. After combustion, the B1-grade sheath material can quickly form a dense and hard shell, covering the outer surface of the steel strip without falling off, thus preventing the spread of flames and the intrusion of external flames into the optical cable.

[0055] The B1-grade sheath material with a combustion dripping grade of d0 is the B1-grade flame-retardant sheath material with a combustion dripping grade of d0 as described in the first aspect of the present invention and / or the B1-grade flame-retardant sheath material with a combustion dripping grade of d0 prepared by the preparation method described in the second aspect of the present invention.

[0056] To obtain a Class B1 flame-retardant optical cable with a combustion dripping rating of d0, the Class B1 sheath material with a combustion dripping rating of d0 from the first aspect of this invention needs to be combined with the optical cable structure of this invention to form a finished optical cable. The combustion performance of the optical cable is then tested according to the Class B1 requirements of standard GB / T31247. When the prepared optical cable burns, the outer sheath carbonizes to form a hard and dense shell, which can block the impact of external flames and the combustion expansion of internal combustibles without detachment, achieving a combustion dripping rating of d0. Simultaneously, the entire optical cable has a low heat release rate and low calorific value, meeting the Class B1 flame-retardant requirements.

[0057] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0058] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Unless otherwise specified, specific experimental or operational conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0059] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0060] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0061] The suppliers and brands of the B1-grade sheathing material that meets the d0 rating for combustion dripping are as follows: The ethylene-vinyl acetate copolymer is supplied by Mitsui Chemicals, Japan, and the brand name is EVAFLEX. 420; the linear low-density polyethylene manufacturer is Iranian Petrochemical, grade 0220AA; the ethylene-octene copolymer manufacturer is Dow Chemical of Thailand, grade 8100; the polyvinyl alcohol is from Kuraray of Japan, model PVA117; the black masterbatch manufacturer is Dongguan Nantai New Materials, grade 8808; the aluminum hydroxide manufacturer is Sichuan Qiaoshui Technology, model H-WF-100; the red phosphorus manufacturer is DOMOR of Germany, grade 66G35V0P; the modified montmorillonite in the charring agent is from Hemings, model Bentone-LT; the nano alumina is from Bofeng Aluminum-based Technology, model ZBZK-GWDS; the nano magnesium oxide is from Hangzhou Hengna New Materials, model HN-MG30; the silicone lubricant in the processing aid is from Ticona, model LW90BSX; the antioxidant 1010 manufacturer is Tianjin Lianlong; the antioxidant DLTP is from Panhua Chemical.

[0062] Example 1

[0063] 9.5 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 35 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 1.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer. The mixture was then subjected to internal mixing and granulation to obtain B1-grade sheath material. After passing through a sheath extruder, B1-grade flame-retardant sheath material with a combustion dripping level of d0 (Scheme 2) was obtained. The measured performance of the B1-grade sheath material and the optical cable combustion performance are shown in Tables 1 and 2, respectively.

[0064] Optical cables consist of a semi-dry cable core, an inner sheath, and an outer sheath, from the inside out.

[0065] The semi-dry cable core comprises, from the inside out, a central reinforcing member 4, an assembly, and a water-blocking strip 6. The assembly includes four loose tubes 3 and two filler ropes 5 evenly distributed around the outer periphery of the central reinforcing member 4. Each loose tube 3 contains 12 optical fibers 1, and the space between the optical fibers 1 and the inner wall of the loose tube 3 is filled with fiber grease 2. There are six optical fibers 1 in total. The fiber grease 2 is silicone grease, manufactured by Shanghai Honghui Optical Communication, model LT-410-A. The diameters of the loose tubes 3 and filler ropes 5 are both 1.6–2.8 mm. The loose tubes 3 are made of polybutylene terephthalate. The central reinforcing member 4 is made of phosphated steel wire with a modulus of 190GP. The diameter of the central reinforcing member 4 is 1.7–3.5 mm. The filler ropes 5 are manufactured by Tonglu Yisheng Communication Cable Material Factory, model 1.9 mm. The loose tube 3 and the filler rope 5 are tied to the surface of the central reinforcing member 4 by an SZ twisting method, and the cross-section of the cable core after tying is circular. The thickness of the water-blocking tape 6 is 0.20mm. The water-blocking tape 6 is made of polyester material and coated with water-absorbing resin. It is manufactured by Wuxi Tenghua and its model is 0.20*20mm.

[0066] The inner sheath, from the inside out, comprises an aluminum-plastic composite tape 7 (manufactured by Shanghai Wangxun New Material Technology Co., Ltd., model 0.25*12mm) and an oxygen barrier layer 8 (manufactured by Shanghai Kete, model KT-2000). The aluminum-plastic composite tape 7 longitudinally wraps around the semi-dry cable core. The thickness of the aluminum-plastic composite tape 7 is 0.25mm. The coverage rate of the aluminum-plastic composite tape 7 is 20%. The thickness of the oxygen barrier layer 8 is 1.2–1.5mm.

[0067] The outer sheath layer comprises, from the inside out, a steel-plastic composite strip 9 (manufactured by Shanghai Wangxun New Material Technology Co., Ltd., model 0.25*46mm) and an outer sheath 10 (manufactured by Shanghai Kete). The steel-plastic composite strip 9 is located on the side in contact with the oxygen barrier layer 8. The thickness of the steel-plastic composite strip 9 is 0.25mm. The thickness of the outer sheath 10 is 1.8–2.2mm.

[0068] Example 2

[0069] Take 9 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 35.5 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 1.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant. Mix them evenly in a high-speed mixer, and then obtain B1 grade sheath material through a mortar and granulator. After passing through a sheath extruder, obtain B1 grade flame-retardant sheath material with a combustion dripping level of d0 according to Scheme 2. The sheath wall thickness is 1.8-2.0 mm. The measured performance of B1 grade sheath material and optical cable combustion performance are shown in Table 1 and Table 2, respectively.

[0070] The optical cable structure is the same as in Example 1.

[0071] Example 3

[0072] 8.5 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 36 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 1.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer. The mixture was then subjected to intensive mixing and granulation to obtain B1-grade sheath material. After passing through a sheath extruder, a B1-grade flame-retardant sheath with a combustion drip rate of d0 (Scheme 2) was obtained. The sheath wall thickness was 1.8–2.0 mm. The measured performance of the B1-grade sheath material and the optical cable combustion performance are shown in Tables 1 and 2, respectively.

[0073] The optical cable structure is the same as in Example 1.

[0074] Example 4

[0075] 8.5 kg of ethylene-vinyl acetate copolymer, 3 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 36.5 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 1.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer. The mixture was then subjected to intensive mixing and granulation to obtain B1-grade sheath material. After passing through a sheath extruder, a B1-grade flame-retardant sheath with a combustion drip rate of d0 (Scheme 2) was obtained. The sheath wall thickness was 1.8–2.0 mm. The measured performance of the B1-grade sheath material and the optical cable combustion performance are shown in Tables 1 and 2, respectively.

[0076] The optical cable structure is the same as in Example 1.

[0077] Comparative Example 1

[0078] 12.5 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 32 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 1.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer, and then subjected to internal mixing and granulation to obtain B1 grade sheath material. After passing through a sheath extruder, B1 grade flame-retardant sheath material with a combustion dripping level of d0 was obtained according to Scheme 2. The sheath wall thickness was 1.8-2.0 mm. The measured performance of B1 grade sheath material and optical cable combustion performance are shown in Table 1 and Table 2, respectively.

[0079] The optical cable structure is the same as in Example 1.

[0080] Comparative Example 2

[0081] 11 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 35 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer, and then subjected to internal mixing and granulation to obtain B1 grade sheath material. After passing through a sheath extruder, B1 grade flame-retardant sheath material with a combustion dripping level of d0 was obtained according to Scheme 2. The sheath wall thickness was 1.8-2.0 mm. The measured performance of B1 grade sheath material and optical cable combustion performance are shown in Table 1 and Table 2, respectively.

[0082] The optical cable structure is the same as in Example 1.

[0083] Comparative Example 3

[0084] 10.5 kg of ethylene-vinyl acetate copolymer, 4 kg of linear low-density polyethylene, 2 kg of ethylene-octene copolymer, 2.5 kg of compatibilizer, 0.65 kg of black masterbatch, 32 kg of aluminum hydroxide, 0.25 kg of red phosphorus, 0.5 kg of charring agent, 0.75 kg of silicone lubricant, and 0.2 kg of antioxidant were mixed evenly in a high-speed mixer, and then subjected to internal mixing and granulation to obtain B1 grade sheath material. After passing through a sheath extruder, B1 grade flame-retardant sheath material with a combustion dripping level of d0 was obtained according to Scheme 2. The sheath wall thickness was 1.8-2.0 mm. The measured performance of B1 grade sheath material and optical cable combustion performance are shown in Table 1 and Table 2, respectively.

[0085] The optical cable structure is the same as in Example 1.

[0086] Table 1 Performance test results of Grade B1 protective material

[0087]

[0088]

[0089] As shown in Table 1, the total heat release and heat release rate of the sheath material in the comparative case are much higher than those in the implementation case, which is unfavorable for B1-level combustion. Furthermore, the oxygen index and ignition time are also significantly lower in the comparative case, indicating that its flame-retardant performance is significantly inferior. In comparison, the flame-retardant performance of the implementation case is better, which is beneficial for achieving B1-level flame retardancy in cable production.

[0090] Table 2. Test Results of B1-Level Combustion Performance of Optical Cables

[0091]

[0092]

[0093] As shown in Table 2, the optical cables made in Examples 1-4 all met the d0 drip rate requirement in the B1-level test, and all combustion data met the B1-level performance requirements specified in standard GB / T 31247. The peak heat release rate, peak smoke generation rate, and total heat release in the three comparative examples all exceeded the B1-level performance requirements, and their drip rate was d1, failing to meet the B1-level flame-retardant sheath requirements for a drip rate of d0.

[0094] This invention, through structural design of the optical cable core, oxygen barrier layer, and outer sheath, and focusing on research into the formulation of B1-grade sheath material, manufactures a B1-grade flame-retardant sheath that meets the d0-grade dripping level. In the event of a fire, the entire optical cable achieves B1-grade flame-retardant performance while preventing dripping, ensuring normal communication of the optical fiber for a certain period and minimizing fire damage.

[0095] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0, characterized in that, The B1-grade flame-retardant protective sleeve comprises the following components by weight percentage:

2. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 1, characterized in that, The density of the ethylene-vinyl acetate copolymer is 0.92–0.98 g / cm³. 3 The melt index is 2-4 g / 10 min.

3. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 1, characterized in that, The linear low-density polyethylene has a density of 0.92–0.96 g / cm³. 3 The melt flow index is 0.2–0.5 g / 10 min.

4. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 1, characterized in that, The density of the ethylene-octene copolymer is 0.8–0.92 g / cm³. 3 The melt index is 2-4 g / 10 min.

5. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 1, characterized in that, The compatibilizer is polyvinyl alcohol with a degree of alcoholysis of 86% to 89%.

6. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 1, characterized in that, It also includes one or more of the following conditions: A1) The black masterbatch is polyethylene with added carbon black, and its density is 1.10–1.15 g / cm³. 3 The melt flow index is 10-20 g / 10 min; A2) The flame retardant is aluminum hydroxide and red phosphorus; A3) The charring agent is a mixture of nano-modified montmorillonite, nano-alumina and nano-magnesium oxide; A4) The lubricant is dimethyl silicone oil; A5) The antioxidant is selected from a combination of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-hydroxyphenyl)propionate) and dodecanol thiodipropionate.

7. The B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 as described in claim 6, characterized in that, It also includes one or more of the following conditions: A21) In characteristic A2), the mass ratio of aluminum hydroxide to red phosphorus is 60:0.5 to 70:0.5; A22) In characteristic A2), the particle size of aluminum hydroxide is 1-4 μm; A23) In characteristic A2), the particle size of red phosphorus is 2-5 μm; A31) In feature A3), the nano-modified montmorillonite is modified with an organic ammonium salt; A32) In feature A3), the alumina nanoparticle size is 20–120 nm; In feature A3), the nano-zinc oxide particles have a diameter of 20–80 nm; The mass ratio of dimethyl silicone oil, pentaerythritol tetrakis(β-(3,5-di-tert-butyl-hydroxyphenyl)propionate) and dodecanol thiodipropionate in A41 is 3:1:1 to 5:1:

1.

8. The method for preparing a Class B1 flame-retardant protective sleeve with a combustion dripping grade of d0 according to any one of claims 1-7, characterized in that, The preparation method includes mixing, kneading, granulating, pelletizing, collecting and packaging ethylene-vinyl acetate copolymer, linear low-density polyethylene, ethylene-octene copolymer, compatibilizer, black masterbatch, aluminum hydroxide, red phosphorus, charring agent, lubricant and antioxidant to produce a B1 grade flame-retardant protective sleeve with a combustion drip grade of d0.

9. The application of the B1-grade flame-retardant sheath with a combustion dripping grade of d0 as described in any one of claims 1-7 and / or the B1-grade flame-retardant sheath with a combustion dripping grade of d0 prepared by the preparation method according to claim 8 in optical cables.

10. An optical cable, characterized in that, The optical cable comprises, from the inside out, a semi-dry cable core, an inner sheath, and an outer sheath. The semi-dry cable core comprises, from the inside out, a central reinforcing member (4), an assembly, and a water-blocking tape (6). The assembly comprises multiple loose tubes (3) evenly distributed along the outer periphery of the central reinforcing member (4) and multiple filler ropes (5). Each loose tube (3) contains multiple optical fibers (1), and fiber grease (2) is filled between the optical fibers (1) and the inner wall of the loose tube (3). The inner sheath comprises, from the inside out, an aluminum-plastic composite tape (6) and an oxygen barrier layer (7). The aluminum-plastic composite tape (6) is located on the side in contact with the water-blocking tape (5). The oxygen barrier layer (7) is located on the side in contact with the outer sheath. The outer sheath comprises a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 according to any one of claims 1-7 and / or a B1-grade flame-retardant protective sleeve with a combustion dripping grade of d0 prepared by the preparation method according to claim 8.

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