Multilayer co-extrusion barrier type solvent-resistant cable sheath structure and preparation method

Abstract

The present application relates to the technical field of wire and cable materials, and particularly relates to a multilayer co-extrusion barrier type solvent corrosion resistant cable sheath structure and a preparation method thereof, the preparation method comprising the following steps: putting ethylene-vinyl alcohol copolymer, polyvinylidene fluoride and additives into a first extruder according to a preset proportion, putting chlorosulfonated polyethylene, polyvinyl chloride and additives into a second extruder according to a preset proportion, and putting polyvinylidene fluoride, polymethyl methacrylate and additives into a third extruder according to a preset proportion; and sending the obtained melt into a three-layer co-extrusion mold, and obtaining the cable sheath structure after cooling and setting. The inner layer is prepared by compounding ethylene-vinyl alcohol copolymer and polyvinylidene fluoride, the intermediate layer is prepared by compounding chlorosulfonated polyethylene and polyvinyl chloride, and the outer layer is prepared by compounding polyvinylidene fluoride and polymethyl methacrylate, so that the weather resistance and wear resistance are improved, and the cable sheath structure with excellent solvent corrosion resistance, good interlayer bonding force, weather resistance and long-term use stability is provided.

Description

Technical Field

[0001] This invention relates to the field of wire and cable materials technology, and in particular to a multi-layer co-extruded barrier type solvent corrosion resistant cable sheath structure and its preparation method. Background Technology

[0002] Cables are increasingly used in petrochemical, marine engineering, and wastewater treatment industries. These environments often contain large amounts of organic solvents and acidic / alkaline media, placing stringent requirements on the corrosion resistance of cable sheath materials. Insufficient solvent corrosion resistance in the cable sheath can lead to swelling and cracking, allowing moisture and corrosive media to penetrate the cable, causing a decline in insulation performance or even short-circuit faults, severely impacting the cable's service life and operational safety.

[0003] Currently, the main technical approaches to improving the solvent corrosion resistance of cable sheaths include using materials with excellent corrosion resistance, such as fluoroplastics and chlorosulfonated polyethylene, as the main sheath material. However, a single material often struggles to simultaneously achieve solvent corrosion resistance, good mechanical properties, and processability. Fluoroplastics offer excellent solvent resistance but are expensive and lack flexibility; chlorosulfonated polyethylene has good chemical resistance but limited barrier properties; while adding ordinary fillers can improve barrier properties, the interfacial bonding between the filler and the matrix is ​​insufficient, leading to detachment after long-term use and performance degradation. Furthermore, although multi-layer composite sheath structures have been proposed to combine the advantages of different materials, existing multi-layer structures often suffer from poor interlayer bonding and delamination, and it is difficult to precisely control the uniformity of layer thickness and the quality of interfacial fusion during co-extrusion molding.

[0004] Therefore, there is a need for a cable sheath structure and preparation method that combines resistance to solvent corrosion, interlayer bonding strength, and long-term stability. Summary of the Invention

[0005] The main objective of this invention is to provide a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure and its preparation method, aiming to solve the problem that existing cable materials are difficult to simultaneously possess solvent corrosion resistance, interlayer bonding strength, and long-term stability.

[0006] To achieve the above objectives, this invention proposes a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure. The cable sheath structure comprises, from the inside out, an inner layer, a middle layer, and an outer layer, co-extruded sequentially. The layers are, by weight, […].

[0007] The raw materials for preparing the inner layer include: 40-60 parts of ethylene-vinyl alcohol copolymer, 20-30 parts of polyvinylidene fluoride, 5-12 parts of composite barrier filler, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of lubricant;

[0008] The raw materials for preparing the intermediate layer include: 35-50 parts of chlorosulfonated polyethylene, 30-40 parts of polyvinyl chloride, 3-8 parts of compatibilizer, 15-25 parts of reinforcing filler, and 0.8-2 parts of crosslinking agent.

[0009] The raw materials for preparing the outer layer include: 40-50 parts of polyvinylidene fluoride, 15-25 parts of polymethyl methacrylate, 8-15 parts of weather-resistant filler, 0.5-1.5 parts of light stabilizer, and 1-3 parts of wear-resistant modifier.

[0010] The thickness ratio of the inner layer, the middle layer, and the outer layer is 1:(1.5~2.5):(0.8~1.2).

[0011] Furthermore, the composite barrier filler is a composite of layered silicate and nano-silica, wherein the mass ratio of layered silicate to nano-silica is (2~4):1.

[0012] Further, the layered silicate includes at least one of organic quaternary ammonium salt modified montmorillonite or organic quaternary ammonium salt modified bentonite, wherein the interlayer spacing of the organic quaternary ammonium salt modified montmorillonite or the organic quaternary ammonium salt modified bentonite is 2.2 nm to 3.5 nm.

[0013] Furthermore, the solubilizer is maleic anhydride-grafted polypropylene, and the grafting rate of the maleic anhydride-grafted polypropylene is 0.8%~1.5%.

[0014] Furthermore, the surface of the nano-silica is treated with a silane coupling agent, wherein the silane coupling agent is γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0015] This invention also proposes a method for preparing a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure, the method comprising the following steps:

[0016] Ethylene-vinyl alcohol copolymer, polyvinylidene fluoride, composite barrier filler, antioxidant, and lubricant are fed into the first extruder according to a preset ratio. Chlorosulfonated polyethylene, polyvinyl chloride, compatibilizer, reinforcing filler, and crosslinking agent are fed into the second extruder according to a preset ratio. Polyvinylidene fluoride, polymethyl methacrylate, weather-resistant filler, light stabilizer, and wear-resistant modified material are fed into the third extruder according to a preset ratio.

[0017] The first melt, second melt, and third melt obtained from the first extruder, second extruder, and third extruder respectively are simultaneously fed into a three-layer co-extrusion die, so that the inner layer, middle layer, and outer layer are combined and composited in the die. After cooling and shaping, a cable sheath structure is obtained.

[0018] The temperature of the three-layer co-extrusion die is controlled at 200℃~220℃, the die head temperature of the first extruder is 210℃~220℃, the die head temperature of the second extruder is 180℃~190℃, and the die head temperature of the third extruder is 200℃~210℃. The melt viscosity ratio of the first melt to the second melt at the die inlet is 0.8~1.2, and the melt viscosity ratio of the second melt to the third melt is 0.9~1.3.

[0019] Furthermore, the preparation method of the composite barrier filler includes:

[0020] Layered silicate was added to an aqueous solution containing a quaternary ammonium salt surface modifier, and the mixture was stirred at 70℃~85℃ for 1.5h~3h. After filtration and drying, the organically modified layered silicate was obtained.

[0021] Nano-silica was ultrasonically dispersed in an ethanol solution, a silane coupling agent was added, and the mixture was reacted at 50℃~70℃ for 1h~2h, then dried to obtain surface-modified nano-silica.

[0022] Organically modified layered silicates are mixed with surface-modified nano-silica to obtain a composite barrier filler.

[0023] This invention improves the cable sheath's barrier properties against organic solvents by using an inner layer made from a blend of ethylene-vinyl alcohol copolymer and polyvinylidene fluoride; the middle layer, made from a blend of chlorosulfonated polyethylene and polyvinyl chloride, enhances the sheath's mechanical strength and thermal stability; and the outer layer, made from a blend of polyvinylidene fluoride and polymethyl methacrylate, improves weather resistance and abrasion resistance. Simultaneously, optimizing the thickness ratio between the inner, middle, and outer layers provides excellent interlayer bonding and anti-delamination properties. This invention offers a cable sheath structure that combines excellent solvent corrosion resistance, good interlayer bonding, weather resistance, and long-term service stability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the processes shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic flowchart illustrating the preparation method of a multilayer co-extruded barrier-type solvent-resistant cable sheath structure according to an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0029] Currently, the main technical approaches to improving the solvent corrosion resistance of cable sheaths fall into three categories: First, using a single high-performance material as the sheath body, such as polyvinylidene fluoride, perfluoroethylene propylene, and chlorinated polyethylene. While fluoroplastics have excellent chemical corrosion resistance, they are expensive and lack flexibility, making them prone to stress cracking during cable bending and installation. Chlorinated polyethylene has good oil resistance but poor weather resistance and is prone to aging and hardening with long-term use. Therefore, a single high-performance material often cannot simultaneously achieve excellent solvent corrosion resistance, mechanical properties, and processability. Second, adding barrier fillers to the polymer matrix, such as layered silicates and two-dimensional sheet materials (such as mica and graphene). First, it delays the penetration of solvent molecules. However, the interfacial bonding force between ordinary fillers and polymer matrix is ​​insufficient, and they are prone to detachment during long-term use or thermal aging, forming microscopic voids and leading to performance degradation. Second, multi-layer composite structures are adopted to combine material layers with different functions in order to combine the advantages of each layer. However, multi-layer structures have problems such as insufficient interlayer bonding force, lack of optimization of the thickness ratio of each layer, and poor processing compatibility. Moreover, most multi-layer structures are only evaluated for single solvents or room temperature environments. However, in actual industrial applications, there are often mixed corrosion from multiple solvents and accelerated corrosion due to temperature rise. The existing multi-layer structures are still far from sufficient in terms of long-term stability.

[0030] Based on this, the embodiments of this application provide a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure. The cable sheath structure consists of an inner layer, a middle layer, and an outer layer co-extruded sequentially from the inside out, wherein, by weight parts,

[0031] The raw materials for preparing the inner layer include: 40-60 parts of ethylene-vinyl alcohol copolymer, 20-30 parts of polyvinylidene fluoride, 5-12 parts of composite barrier filler, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of lubricant;

[0032] The raw materials for preparing the intermediate layer include: 35-50 parts of chlorosulfonated polyethylene, 30-40 parts of polyvinyl chloride, 3-8 parts of compatibilizer, 15-25 parts of reinforcing filler, and 0.8-2 parts of crosslinking agent;

[0033] The raw materials for preparing the outer layer include: 40-50 parts of polyvinylidene fluoride, 15-25 parts of polymethyl methacrylate, 8-15 parts of weather-resistant filler, 0.5-1.5 parts of light stabilizer, and 1-3 parts of wear-resistant modifier;

[0034] The thickness ratio of the inner layer, the middle layer, and the outer layer is 1:(1.5~2.5):(0.8~1.2).

[0035] Specifically, in this invention, the cable sheath structure is composed of an inner layer, a middle layer, and an outer layer that are co-extruded and composited sequentially from the inside out. Through the synergistic effect of the three layers, the inner layer provides the main solvent barrier function, the middle layer provides mechanical support and interlayer transition, and the outer layer provides weather resistance and abrasion resistance protection, thereby obtaining a cable sheath with excellent comprehensive performance.

[0036] Specifically, the inner layer materials are ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene fluoride (PVDF), composite barrier filler, antioxidant, and lubricant. EVOH and PVDF are compounded, utilizing the high barrier properties of EVOH and the chemical resistance of PVDF to form a dense barrier layer. The composite barrier filler further extends the penetration path of solvent molecules, improving the barrier effect. The intermediate layer is prepared from chlorosulfonated polyethylene (CSM), polyvinyl chloride (PVC), compatibilizer, reinforcing filler, and crosslinking agent. CSM provides excellent ozone and acid / alkali resistance, while PVC provides good processing performance. CSM and PVC achieve good compatibility through the compatibilizer. The reinforcing filler improves mechanical strength, and the crosslinking agent forms a partially crosslinked structure in the intermediate layer, enhancing interlayer bonding. The outer layer is prepared from polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), weather-resistant filler, light stabilizer, and wear-resistant modifier. PVDF provides excellent weather resistance and chemical resistance, while PMMA enhances surface hardness and gloss. Weather-resistant fillers and light stabilizers work synergistically to improve aging resistance, and wear-resistant modifiers improve surface wear resistance.

[0037] More specifically, the present invention controls the thickness ratio of the inner layer, the middle layer and the outer layer to be 1:(1.5~2.5):(0.8~1.2). Controlling this thickness ratio can optimize the overall performance of the cable sheath. When the middle layer is too thin, the interlayer bonding force decreases; when the middle layer is too thick, the overall flexibility of the cable sheath decreases; when the outer layer is too thin, the weather resistance is insufficient; when it is too thick, the cost increases and the bending performance is affected.

[0038] In one embodiment, the composite barrier filler is a composite of layered silicate and nano-silica, with a mass ratio of layered silicate to nano-silica of (2~4):1.

[0039] In one embodiment, the layered silicate includes at least one of organic quaternary ammonium salt modified montmorillonite or organic quaternary ammonium salt modified bentonite, wherein the interlayer spacing of the organic quaternary ammonium salt modified montmorillonite or organic quaternary ammonium salt modified bentonite is 2.2 nm to 3.5 nm.

[0040] In this embodiment, hexadecyltrimethylammonium bromide or octadecyltrimethylammonium chloride is used for intercalation modification to expand the interlayer spacing to 2.2nm~3.5nm, which is beneficial for polymer molecular chain insertion and improves compatibility and barrier properties.

[0041] In one embodiment, the solubilizer is maleic anhydride-grafted polypropylene, and the grafting rate of the maleic anhydride-grafted polypropylene is 0.8% to 1.5%.

[0042] In one embodiment, the surface of the nano-silica is treated with a silane coupling agent, which is γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0043] like Figure 1 As shown, this invention also proposes a method for preparing a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure, the method comprising the following steps:

[0044] Step S10: Ethylene-vinyl alcohol copolymer, polyvinylidene fluoride, composite barrier filler, antioxidant, and lubricant are fed into the first extruder according to a preset ratio; chlorosulfonated polyethylene, polyvinyl chloride, compatibilizer, reinforcing filler, and crosslinking agent are fed into the second extruder according to a preset ratio; and polyvinylidene fluoride, polymethyl methacrylate, weather-resistant filler, light stabilizer, and wear-resistant modified material are fed into the third extruder according to a preset ratio.

[0045] Step S20: The first melt, the second melt, and the third melt obtained from the first extruder, the second extruder, and the third extruder are simultaneously fed into a three-layer co-extrusion die, so that the inner layer, the middle layer, and the outer layer are combined and composited in the die. After cooling and shaping, a cable sheath structure is obtained.

[0046] The temperature of the three-layer co-extrusion die is controlled at 200℃~220℃, the die head temperature of the first extruder is 210℃~220℃, the die head temperature of the second extruder is 180℃~190℃, and the die head temperature of the third extruder is 200℃~210℃. The melt viscosity ratio of the first melt to the second melt at the die inlet is 0.8~1.2, and the melt viscosity ratio of the second melt to the third melt is 0.9~1.3.

[0047] In one embodiment, the method for preparing the composite barrier filler includes:

[0048] Step T10: Add the layered silicate to an aqueous solution containing a quaternary ammonium salt surface modifier, stir and react at 70℃~85℃ for 1.5h~3h, filter and dry to obtain the organically modified layered silicate;

[0049] Step T20: Disperse nano-silica in an ethanol solution by ultrasonication, add silane coupling agent, react at 50℃~70℃ for 1h~2h, dry, and obtain surface-modified nano-silica;

[0050] Step T30: The organically modified layered silicate is mixed with the surface-modified nano-silica to obtain a composite barrier filler.

[0051] The present invention also discloses the following specific embodiments.

[0052] Example 1:

[0053] The proportions of raw materials for each layer are as follows:

[0054] Inner layer: 50 parts EVOH (Japan Synthetic Chemicals, F171B), 25 parts PVDF (Arkema, Kynar740), 8 parts composite barrier filler, 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0055] Intermediate layer: 42 parts CSM (Tosoh, TS-530), 35 parts PVC (SG-5), 5 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0056] Outer layer: 45 parts PVDF (Arkema, Kynar740), 20 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0057] The preparation steps are as follows:

[0058] Step S1: Prepare composite barrier filler. Add montmorillonite (Zhejiang Fenghong, DK4) to an aqueous solution of hexadecyltrimethylammonium bromide (the amount of hexadecyltrimethylammonium bromide aqueous solution is 3% of montmorillonite), stir at 80℃ for 2h, filter and dry to obtain organic quaternary ammonium salt modified montmorillonite. Disperse nano-silica (Degussa, A200) ultrasonically in a solution of ethanol, add KH560 (the amount is 4% of the mass of nano-silica), and transfer to 60℃ to react for 1.5h. After drying, obtain organic quaternary ammonium salt modified nano-silica. Mix organic quaternary ammonium salt modified montmorillonite and organic quaternary ammonium salt modified nano-silica at a mass ratio of 3:1 and stir at 90℃ for 15min to obtain composite barrier filler.

[0059] Step S2: After mixing the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, the mixture is fed into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 210°C.

[0060] Step S3: Control the extrusion speed so that the thicknesses of the inner layer, middle layer and outer layer are 0.3mm, 0.6mm and 0.3mm respectively, with a thickness ratio of 1:2:1.

[0061] The viscosity ratio of the first melt to the second melt is 0.95, and the viscosity ratio of the second melt to the third melt is 1.1.

[0062] Example 2:

[0063] The proportions of raw materials for each layer are as follows:

[0064] Inner layer: 55 parts EVOH (Japan Synthetic Chemicals, F171B), 22 parts PVDF (Arkema, Kynar740), 10 parts composite barrier filler, 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0065] Intermediate layer: 45 parts CSM (Tosoh, TS-530), 38 parts PVC (SG-5), 6 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0066] Outer layer: 48 parts PVDF (Arkema, Kynar740), 18 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0067] The preparation steps are as follows:

[0068] Step S1: Prepare composite barrier filler. Add montmorillonite (Zhejiang Fenghong, DK4) to an aqueous solution of hexadecyltrimethylammonium bromide (the amount of hexadecyltrimethylammonium bromide aqueous solution is 3% of montmorillonite), stir at 80℃ for 2h, filter and dry to obtain organic quaternary ammonium salt modified montmorillonite. Disperse nano-silica (Degussa, A200) ultrasonically in a solution of ethanol, add KH560 (the amount is 4% of the mass of nano-silica), and transfer to 60℃ to react for 1.5h. After drying, obtain organic quaternary ammonium salt modified nano-silica. Mix organic quaternary ammonium salt modified montmorillonite and organic quaternary ammonium salt modified nano-silica at a mass ratio of 3:1 and stir at 90℃ for 15min to obtain composite barrier filler.

[0069] Step S2: After mixing the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, the mixture is fed into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 210°C.

[0070] Step S3: Control the extrusion speed so that the thicknesses of the inner layer, middle layer and outer layer are 0.25mm, 0.55mm and 0.25mm respectively, with a thickness ratio of 1:2.2:1.

[0071] The viscosity ratio of the first melt to the second melt is 1.1, and the viscosity ratio of the second melt to the third melt is 1.2.

[0072] Example 3:

[0073] The proportions of raw materials for each layer are as follows:

[0074] Inner layer: 45 parts EVOH (Japan Synthetic Chemicals, F171B), 28 parts PVDF (Arkema, Kynar740), 6 parts composite barrier filler, 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0075] Intermediate layer: 38 parts CSM (Tosoh, TS-530), 35 parts PVC (SG-5), 5 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0076] Outer layer: 42 parts PVDF (Arkema, Kynar740), 22 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0077] The preparation steps are as follows:

[0078] Step S1: Prepare composite barrier filler. Add montmorillonite (Zhejiang Fenghong, DK4) to an aqueous solution of hexadecyltrimethylammonium bromide (the amount of hexadecyltrimethylammonium bromide aqueous solution is 3% of montmorillonite), stir at 80℃ for 2h, filter and dry to obtain organic quaternary ammonium salt modified montmorillonite. Disperse nano-silica (Degussa, A200) ultrasonically in a solution of ethanol, add KH560 (the amount is 4% of the mass of nano-silica), and transfer to 60℃ to react for 1.5h. After drying, obtain organic quaternary ammonium salt modified nano-silica. Mix organic quaternary ammonium salt modified montmorillonite and organic quaternary ammonium salt modified nano-silica at a mass ratio of 3:1 and stir at 90℃ for 15min to obtain composite barrier filler.

[0079] Step S2: After mixing the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, the mixture is fed into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 210°C.

[0080] Step S3: Control the extrusion speed so that the thicknesses of the inner layer, middle layer and outer layer are 0.35mm, 0.63mm and 0.32mm respectively, and the thickness ratio is 1:1.8:0.9.

[0081] The viscosity ratio of the first melt to the second melt is 0.85, and the viscosity ratio of the second melt to the third melt is 0.95.

[0082] Comparative Example 1:

[0083] The proportions of raw materials for each layer are as follows:

[0084] Inner layer: 50 parts EVOH (Japan Synthetic Chemicals, F171B), 25 parts PVDF (Arkema, Kynar740), 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0085] Intermediate layer: 42 parts CSM (Tosoh, TS-530), 35 parts PVC (SG-5), 5 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0086] Outer layer: 45 parts PVDF (Arkema, Kynar740), 20 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0087] The preparation steps are as follows:

[0088] Step S1: Mix the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, and then feed them into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 210°C.

[0089] Step S2: Control the extrusion speed so that the thicknesses of the inner layer, middle layer, and outer layer are 0.3mm, 0.6mm, and 0.3mm respectively, with a thickness ratio of 1:2:1.

[0090] The melt viscosity ratio of the first melt to the second melt is 0.95, and the melt viscosity ratio of the second melt to the third melt is 1.1. It can be seen that, compared with Example 1, the inner layer material in Comparative Example 1 did not contain composite barrier filler, which is used to verify the importance of thickness ratio optimization in the present invention.

[0091] Comparative Example 2:

[0092] The proportions of raw materials for each layer are as follows:

[0093] Inner layer: 50 parts EVOH (Japan Synthetic Chemicals, F171B), 25 parts PVDF (Arkema, Kynar740), 8 parts composite barrier filler, 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0094] Intermediate layer: 42 parts CSM (Tosoh, TS-530), 35 parts PVC (SG-5), 5 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0095] Outer layer: 45 parts PVDF (Arkema, Kynar740), 20 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0096] The preparation steps are as follows:

[0097] Step S1: Prepare composite barrier filler. Add montmorillonite (Zhejiang Fenghong, DK4) to an aqueous solution of hexadecyltrimethylammonium bromide (the amount of hexadecyltrimethylammonium bromide aqueous solution is 3% of montmorillonite), stir at 80℃ for 2h, filter and dry to obtain organic quaternary ammonium salt modified montmorillonite. Disperse nano-silica (Degussa, A200) ultrasonically in a solution of ethanol, add KH560 (the amount is 4% of the mass of nano-silica), and transfer to 60℃ to react for 1.5h. After drying, obtain organic quaternary ammonium salt modified nano-silica. Mix organic quaternary ammonium salt modified montmorillonite and organic quaternary ammonium salt modified nano-silica at a mass ratio of 3:1 and stir at 90℃ for 15min to obtain composite barrier filler.

[0098] Step S2: After mixing the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, the mixture is fed into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 210°C.

[0099] Step S3: Control the extrusion speed so that the thicknesses of the inner layer, middle layer and outer layer are 0.4mm, 0.4mm and 0.4mm respectively, with a thickness ratio of 1:1:1.

[0100] The melt viscosity ratio of the first melt to the second melt is 0.95, and the melt viscosity ratio of the second melt to the third melt is 1.1. It can be seen that, compared with Example 1, the thickness ratio of each layer in Comparative Example 2 is adjusted to 1:1:1, which is used to verify the importance of thickness ratio optimization in the present invention.

[0101] Comparative Example 3:

[0102] The proportions of raw materials for each layer are as follows:

[0103] Inner layer: 50 parts EVOH (Japan Synthetic Chemicals, F171B), 25 parts PVDF (Arkema, Kynar740), 8 parts composite barrier filler, 1 part antioxidant (1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 1 part calcium stearate lubricant;

[0104] Intermediate layer: 42 parts CSM (Tosoh, TS-530), 35 parts PVC (SG-5), 5 parts solubilizer (PP-g-MAH, grafting rate 1.2%), 18 parts reinforcing filler (1250 mesh calcined kaolin), 10 parts precipitated barium sulfate (3000 mesh), 1.2 parts dicumyl peroxide (DCP);

[0105] Outer layer: 45 parts PVDF (Arkema, Kynar740), 20 parts PMMA (Chimei, CM-205), 10 parts titanium dioxide (rutile type, R996), 0.8 parts light stabilizer (light stabilizer 292, a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidine) sebacate and 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidine) sebacate), and 2 parts wear-resistant modifier (molybdenum disulfide).

[0106] The preparation steps are as follows:

[0107] Step S1: Prepare composite barrier filler. Add montmorillonite (Zhejiang Fenghong, DK4) to an aqueous solution of hexadecyltrimethylammonium bromide (the amount of hexadecyltrimethylammonium bromide aqueous solution is 3% of montmorillonite), stir at 80℃ for 2h, filter and dry to obtain organic quaternary ammonium salt modified montmorillonite. Disperse nano-silica (Degussa, A200) ultrasonically in a solution of ethanol, add KH560 (the amount is 4% of the mass of nano-silica), and transfer to 60℃ to react for 1.5h. After drying, obtain organic quaternary ammonium salt modified nano-silica. Mix organic quaternary ammonium salt modified montmorillonite and organic quaternary ammonium salt modified nano-silica at a mass ratio of 3:1 and stir at 90℃ for 15min to obtain composite barrier filler.

[0108] Step S2: After mixing the raw materials for the inner layer, middle layer, and outer layer according to the specified ratio, the mixture is fed into the corresponding co-extruders. The first extruder is set with a feeding section of 165°C, a compression section of 185°C, a metering section of 205°C, and a die head of 215°C. The second extruder is set with a feeding section of 145°C, a compression section of 165°C, a metering section of 175°C, and a die head of 185°C. The third extruder is set with a feeding section of 175°C, a compression section of 195°C, a metering section of 215°C, and a die head of 205°C. The temperature of the co-extrusion die is controlled at 180°C.

[0109] Step S3: Control the extrusion speed so that the thicknesses of the inner layer, middle layer and outer layer are 0.3mm, 0.6mm and 0.3mm respectively, with a thickness ratio of 1:2:1.

[0110] The melt viscosity ratio of the first melt to the second melt is 0.95, and the melt viscosity ratio of the second melt to the third melt is 1.1. It can be seen that, compared with Example 1, Comparative Example 3 adjusted the co-extrusion die temperature and controlled the co-extrusion die temperature at 180°C to demonstrate the criticality of the die temperature range. Specifically, the co-extrusion die temperature of Comparative Example 3 was controlled at 180°C (lower than 200°C~220°C in this invention), resulting in poor interlayer bonding.

[0111] This invention also discloses performance testing, wherein the cable sheath structures prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing, and the performance test contents are as follows:

[0112] 1. Solvent resistance: According to GB / T 1690-2010 standard, the cable sheath samples prepared in Examples 1-3 and Control Examples 1-3 were immersed in a toluene-ethanol mixed solvent (volume ratio 7:3) at 70°C for 1000 hours, and the change rate of tensile strength and mass before and after immersion were tested.

[0113] 2. Interlayer peel strength: According to GB / T 2791-1995 standard, the cable sheath samples prepared in Examples 1-3 and Control Examples 1-3 respectively were tested for the peel strength between the inner layer and the middle layer using a universal testing machine.

[0114] 3. Interlayer bonding strength after thermal aging: The cable sheath samples prepared in Examples 1-3 and Control Examples 1-3 were aged in hot air at 100°C for 168 hours. The interlayer peel strength was tested by a universal testing machine and the retention rate was calculated.

[0115] The specific performance test results are shown in the table below:

[0116] Table 1. Performance test results of cable sheath samples prepared in Examples 1-3 and Comparative Examples 1-3

[0117]

[0118] Experimental conclusion:

[0119] Based on the experimental data from the above three sets of embodiments and two sets of comparative embodiments, it can be seen that the cable sheath structures of embodiments 1-3 are significantly superior to those of comparative embodiments 1-3 in terms of solvent resistance, interlayer bonding strength, and thermal aging stability. In comparative embodiment 1, due to the absence of composite barrier filler in the inner layer, the solvent molecule penetration path is shortened, resulting in a significant decrease in solvent resistance. The tensile strength retention rate is only 78.3%, and the mass change rate reaches 7.6%, proving that the composite barrier filler is a key component for improving solvent resistance. In comparative embodiment 2, the middle layer is too thin, resulting in insufficient interlayer bonding strength. The interlayer peel strength is only 2.9 N / mm, which decreases to 68.3% after thermal aging, proving that the optimization of the thickness ratio is crucial for the stability of interlayer bonding. In comparative embodiment 3, the mold temperature is controlled at 180℃, which is lower than the 200℃~220℃ range specified in this invention, resulting in insufficient interface fusion. The interlayer peel strength is only 2.5 N / mm, which decreases to 60.2% after thermal aging, proving that the synergistic control of mold temperature and melt viscosity ratio has an important impact on the quality of interlayer bonding.

[0120] This invention improves the cable sheath's ability to block organic solvents by using an inner layer made from a blend of ethylene-vinyl alcohol copolymer and polyvinylidene fluoride, and adding a specific proportion of composite barrier filler. The middle layer is made from a blend of chlorosulfonated polyethylene and polyvinyl chloride, compatibilized by maleic anhydride-grafted polypropylene, and reinforced with fillers and crosslinking agents to improve the sheath's mechanical strength and thermal stability. The outer layer is made from a blend of polyvinylidene fluoride and polymethyl methacrylate, with added weather-resistant fillers and light stabilizers to improve weather resistance and abrasion resistance. Simultaneously, the thickness ratio between the inner, middle, and outer layers is optimized to avoid stress concentration caused by thickness imbalance, ensuring uniform fusion at the interfaces of each layer and providing excellent interlayer bonding and anti-delamination performance. This invention provides a cable sheath structure that combines excellent solvent corrosion resistance, good interlayer bonding, weather resistance, and long-term service stability.

[0121] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A multi-layer co-extruded barrier-type solvent-resistant cable sheath structure, characterized in that, The cable sheath structure consists of an inner layer, a middle layer, and an outer layer co-extruded and composited in sequence from the inside out, wherein, by weight, The raw materials for preparing the inner layer include: 40-60 parts of ethylene-vinyl alcohol copolymer, 20-30 parts of polyvinylidene fluoride, 5-12 parts of composite barrier filler, 0.5-1.5 parts of antioxidant, and 0.5-1.5 parts of lubricant; The raw materials for preparing the intermediate layer include: 35-50 parts of chlorosulfonated polyethylene, 30-40 parts of polyvinyl chloride, 3-8 parts of compatibilizer, 15-25 parts of reinforcing filler, and 0.8-2 parts of crosslinking agent. The raw materials for preparing the outer layer include: 40-50 parts of polyvinylidene fluoride, 15-25 parts of polymethyl methacrylate, 8-15 parts of weather-resistant filler, 0.5-1.5 parts of light stabilizer, and 1-3 parts of wear-resistant modifier. The thickness ratio of the inner layer, the middle layer, and the outer layer is 1:(1.5~2.5):(0.8~1.2).

2. The multi-layer co-extruded barrier-type solvent-resistant cable sheath structure as described in claim 1, characterized in that, The composite barrier filler is a composite of layered silicate and nano-silica, and the mass ratio of the layered silicate to nano-silica is (2~4):

1.

3. The multi-layer co-extruded barrier-type solvent-resistant cable sheath structure as described in claim 2, characterized in that, The layered silicate includes at least one of organic quaternary ammonium salt modified montmorillonite or organic quaternary ammonium salt modified bentonite, wherein the interlayer spacing of the organic quaternary ammonium salt modified montmorillonite or the organic quaternary ammonium salt modified bentonite is 2.2 nm to 3.5 nm.

4. The multi-layer co-extruded barrier-type solvent-resistant cable sheath structure as described in claim 1, characterized in that, The solubilizer is maleic anhydride-grafted polypropylene, and the grafting rate of the maleic anhydride-grafted polypropylene is 0.8%~1.5%.

5. The multi-layer co-extruded barrier-type solvent-resistant cable sheath structure as described in claim 1, characterized in that, The surface of the nano-silica is treated with a silane coupling agent, wherein the silane coupling agent is γ-glycidoxypropyltrimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

6. A method for preparing a multi-layer co-extruded barrier-type solvent-resistant cable sheath structure, characterized in that, The preparation method includes the following steps: Ethylene-vinyl alcohol copolymer, polyvinylidene fluoride, composite barrier filler, antioxidant, and lubricant are fed into the first extruder according to a preset ratio. Chlorosulfonated polyethylene, polyvinyl chloride, compatibilizer, reinforcing filler, and crosslinking agent are fed into the second extruder according to a preset ratio. Polyvinylidene fluoride, polymethyl methacrylate, weather-resistant filler, light stabilizer, and wear-resistant modified material are fed into the third extruder according to a preset ratio. The first melt, second melt, and third melt obtained from the first extruder, second extruder, and third extruder respectively are simultaneously fed into a three-layer co-extrusion die, so that the inner layer, middle layer, and outer layer are combined and composited in the die. After cooling and shaping, a cable sheath structure is obtained. The temperature of the three-layer co-extrusion die is controlled at 200℃~220℃, the die head temperature of the first extruder is 210℃~220℃, the die head temperature of the second extruder is 180℃~190℃, and the die head temperature of the third extruder is 200℃~210℃. The melt viscosity ratio of the first melt to the second melt at the die inlet is 0.8~1.2, and the melt viscosity ratio of the second melt to the third melt is 0.9~1.

3.

7. The method for preparing the multi-layer co-extruded barrier-type solvent-resistant cable sheath structure as described in claim 6, characterized in that, The preparation method of the composite barrier filler includes: Layered silicate was added to an aqueous solution containing a quaternary ammonium salt surface modifier, and the mixture was stirred at 70℃~85℃ for 1.5h~3h. After filtration and drying, the organically modified layered silicate was obtained. Nano-silica was ultrasonically dispersed in an ethanol solution, a silane coupling agent was added, and the mixture was reacted at 50℃~70℃ for 1h~2h, then dried to obtain surface-modified nano-silica. Organically modified layered silicates are mixed with surface-modified nano-silica to obtain a composite barrier filler.

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