A water-tight glue, an underwater flexible optical cable having the same, a manufacturing method and applications thereof

Abstract

The application discloses a water-tight adhesive, which comprises the following raw materials in parts by weight: A component: epoxy resin 70-85 parts, expansion monomer 10-20 parts, diluent 20-40 parts, plasticizer 10-20 parts; B component: curing agent 50-60 parts, curing accelerator 10-20 parts, expansion accelerator 10-20 parts. The application also discloses application of the water-tight adhesive in an underwater optical cable, the underwater optical cable and a manufacturing method thereof. The optical cable structure comprises a central reinforcing member, an electric unit, an optical unit, a wrapping tape, a tensile element and an outer sheath, the water-tight adhesive is filled in a gap between the central reinforcing member and the wrapping tape; and / or the water-tight adhesive is filled in a gap between the wrapping tape and the outer sheath. The water-tight adhesive filled in the gap of the optical cable has a water absorption and expansion effect, the filling rate is more than 90%, the water absorption and expansion ratio is 150%-300%, and the bonding strength is greater than or equal to 8 MPa, so that the longitudinal water pressure resistance of the optical cable can be obviously improved, and the optical cable can be applied to a deep sea with a depth of more than 1000 m.

Description

Technical Field

[0001] This invention belongs to the field of underwater optical fiber communication technology, specifically relating to a watertight adhesive, the application of the watertight adhesive, an underwater flexible optical cable with the watertight adhesive, and a method for manufacturing the optical cable. Background Technology

[0002] With the rapid development of fiber optic communication, its application areas have also expanded significantly, such as underwater robots, underwater sonar detection, and underwater monitoring systems.

[0003] As diving depths increase, the demands on the control and information capacity of submersibles also rise. Starting in 1990, underwater cables gradually transitioned from single-cable cables to fiber-optic composite cables. This concept was proposed in 1990 by Nakajoh et al. in Japan. This type of fiber-optic composite cable was first applied to a 7000-meter ROV (UROV7K), which included cameras, light, controllers, and sampling equipment. However, in addition to integrating optoelectronic functions, the increased diving depth placed higher demands on the radial water pressure resistance of the underwater fiber-optic composite cable. Simultaneously, to protect underwater equipment, requirements were also placed on its longitudinal water resistance and water pressure resistance.

[0004] Currently, underwater optical cables integrate optoelectronic units for underwater transmission and employ non-metallic armor to achieve the requirement of a small bending radius. The radial water pressure resistance is primarily provided by the sheath, which is controlled by the sheath material, thickness, and armor structure. In contrast, longitudinal water pressure resistance in cables is achieved through water-blocking adhesives, watertight adhesives, and water-blocking yarns. However, while the transmission medium in cables is copper wire, the transmission medium in optical cables is optical fiber. Optical fiber is far more susceptible to stress than copper wire, and directly using watertight adhesives in cables would prevent the transmission of optical fiber signals. Furthermore, the longitudinal water pressure resistance of existing optical cable watertight adhesives is limited, reaching a maximum of only 3.0 MPa.

[0005] Therefore, the problem of high longitudinal water pressure resistance of underwater optical cables has not yet been solved, limiting their application in deep sea. This places stringent requirements on the packaging and construction of underwater optical cables. Once damaged, seawater can directly reach the underwater system and the surface receiving equipment, causing serious losses. Summary of the Invention

[0006] In view of one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a watertight adhesive, an underwater flexible optical cable having the watertight adhesive, a manufacturing method and application. By filling the gaps of the optical cable with a watertight adhesive that has a water-absorbing and expanding effect, an underwater optical cable resistant to longitudinal water pressure is manufactured while ensuring the requirements of radial water pressure resistance and high tensile strength of the underwater flexible optical cable, thus solving the problem of longitudinal water pressure resistance of underwater optical cables.

[0007] According to a first aspect of the present invention, a watertight adhesive is provided, wherein the raw materials of the watertight adhesive, by weight, comprise:

[0008] Component A: 70-85 parts epoxy resin, 10-20 parts expanded monomer, 20-40 parts diluent, and 10-20 parts plasticizer;

[0009] Component B: 50-60 parts curing agent, 10-20 parts curing accelerator, and 10-20 parts expansion accelerator.

[0010] As a further improvement of the present invention, in component A,

[0011] The expanding monomer includes one or more of TPE / P(AA-co-AM) water-absorbing and expanding monomer, sodium nano-polyacrylate, ethyl methacrylate copolymer, and polyurethane prepolymer; and / or,

[0012] The epoxy resin includes one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and alicyclic epoxy resin; and / or,

[0013] The diluent comprises one or more of ethylene glycol diglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, acrylate glycidyl ether, and benzyl alcohol; and / or,

[0014] The plasticizer is one or more of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0015] As a further improvement of the present invention

[0016] The swelling promoter is one or more of electrospun nanofibers and spiropyran; and / or

[0017] The curing agent is one or more of linoleic acid dimer triethylenetetramine, linoleic acid dimer diethylene, and low molecular weight polyamide; and / or,

[0018] The curing accelerator is one or more of DMP-30 and N,N-dimethylethanolamine.

[0019] As a further improvement of the present invention, the water-tight adhesive has a water absorption swelling ratio of 150% to 300%, preferably 200% to 250%; and / or,

[0020] The bonding strength between the watertight adhesive and the substrate is ≥8MPa, preferably 9MPa~10MPa.

[0021] According to a second aspect of the present invention, an application of the watertight adhesive described above in an underwater optical cable is provided, wherein the watertight adhesive is filled in the gaps of the underwater optical cable or coated on the surface of the underwater optical cable substrate, and the application conditions include:

[0022] The mass ratio of component A to component B is 85-95:10-20, more preferably 90:10; the curing temperature is preferably 15-35℃, more preferably 20-25℃; the curing time is preferably 5-10h, more preferably 6-8h.

[0023] As a further improvement of the present invention, the watertight adhesive has a filling rate of 90% or more in the optical cable gaps, preferably 98% or more.

[0024] According to a third aspect of the present invention, an underwater flexible optical cable is provided, employing the aforementioned watertight adhesive; the optical cable structure includes a central reinforcing member, an electrical unit, an optical unit, a wrapping tape, a tensile element, and an outer sheath; wherein...

[0025] The optical unit and the electrical unit are twisted together around the central reinforcing member to form a cable core; the wrapping tape is wrapped around the outside of the cable core, and the tensile element is twisted around the outside of the wrapping tape; the outer sheath is located on the outermost layer and is extruded outside the tensile element;

[0026] The gap between the central reinforcement and the strap is filled with water-tight adhesive; and / or, the gap between the strap and the outer sheath is filled with water-tight adhesive.

[0027] As a further improvement of the present invention, the surface of the central reinforcing member is coated with water-tight adhesive; and / or, the surfaces of the optical unit and the electrical unit are coated with water-tight adhesive; and / or, the surfaces of the strap and the tensile element are coated with water-tight adhesive.

[0028] As a further improvement of the present invention, the watertight adhesive has a filling rate of more than 90% in the optical cable gap, preferably more than 98%.

[0029] As a further improvement of the present invention, the water-tight adhesive has a water absorption and swelling ratio of 150% to 300%, preferably 200% to 250%; and / or, the adhesion strength between the water-tight adhesive and the substrate is ≥8MPa, preferably between 9MPa and 10MPa.

[0030] According to a fourth aspect of the present invention, a method for manufacturing an underwater flexible optical cable is provided, comprising the following steps:

[0031] The optical unit and the electrical unit are twisted together around the central reinforcing member to form a cable core, and water-tight adhesive is injected during the twisting process.

[0032] Wrap a wrapping tape around the outside of the cable core;

[0033] Tensile-resistant elements are twisted together on the outside of the strapping, and watertight adhesive is injected during twisting.

[0034] An outer sheath is extruded onto the outside of the tensile element;

[0035] Finally, watertight adhesive is cured to produce an underwater flexible optical cable.

[0036] As a further improvement of the present invention

[0037] Before fabrication, a water-tight adhesive is applied to the surface of at least one of the substrates, including the central reinforcing member, optical unit, electrical unit, wrapping tape, and tensile element; or, during fabrication, a water-tight adhesive is applied to the surface of each substrate layer. During application, the corresponding substrate temperature is maintained between 15 and 35°C, and the coating thickness is greater than 0.5 mm.

[0038] When injecting watertight adhesive, the injection pressure is 0.5 to 1.5 MPa.

[0039] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0040] (1) The watertight adhesive of the present invention contains hydrophilic groups in the swelling monomer, which can produce water absorption and swelling effect when interacting with water molecules. Furthermore, the swelling monomer in component A and the swelling promoter in component B work together to provide water molecules with multi-scale water channels inside the optical cable, which can connect the isolated resin groups to the matrix surface to enhance the water absorption and swelling capacity of the material.

[0041] (2) In the underwater flexible optical cable of the present invention, the gaps inside the optical cable are filled with water-blocking adhesive. After absorbing water, the water-tight adhesive can expand and fill these gaps. At the same time, due to the high bonding strength between the water-tight adhesive and the substrate, the water-tight adhesive and the substrate will not fall off under high water pressure conditions, and due to the high bonding strength, it has high stability under high water pressure conditions. Therefore, the underwater flexible optical cable using the water-tight adhesive of the present invention can significantly improve its longitudinal water pressure resistance performance, and can protect the equipment at both ends when used in deep water, reducing the risk of use.

[0042] (3) In the underwater flexible optical cable of the present invention, the central reinforcing member, optical unit, electrical unit, wrapping tape, and tensile element are coated with water-tight adhesive by coating. When the optical unit and electrical unit are twisted together, and when the tensile element is twisted together, the gaps are filled with water-tight adhesive under the pressure of the adhesive injection system, which can ensure that the gaps in the optical cable are filled with sufficient water-tight adhesive. The higher the water-tight adhesive filling rate, the smaller the gaps between the various substrates of the optical cable, and the larger the water absorption expansion ratio. Once water is absorbed, the water-tight adhesive can expand and fill these gaps.

[0043] (4) The underwater flexible optical cable of the present invention can withstand longitudinal water pressure up to 12MPa. It has longitudinal water blocking performance and radial water pressure resistance, high tensile strength and other characteristics. It can be repeatedly deployed and retracted and can be used in the deep sea above 1000m to ensure the photoelectric transmission of underwater equipment. Attached Figure Description

[0044] Figure 1This is a schematic diagram of an underwater flexible optical cable structure according to an embodiment of the present invention.

[0045] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-central reinforcement, 2-electrical unit, 3-optical unit, 4-wrapping tape, 5-tensile element, 6-outer sheath, 7-watertight adhesive. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] The watertight adhesive of this invention is a two-component epoxy resin; by weight, it comprises the following raw materials:

[0048] Component A: 70-85 parts epoxy resin, 10-20 parts expanded monomer, 20-40 parts diluent, and 10-20 parts plasticizer;

[0049] Component B: 50-60 parts curing agent, 10-20 parts curing accelerator, and 10-20 parts expansion accelerator.

[0050] Preferably, in component A, the expanding monomer includes one or more of TPE / P(AA-co-AM) water-absorbing expanding monomer, sodium nano-polyacrylate, ethyl methacrylate copolymer, and polyurethane prepolymer.

[0051] Preferably, in component A, the epoxy resin includes one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and alicyclic epoxy resin.

[0052] Preferably, in component A, the diluent includes one or more of ethylene glycol diglycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, acrylate glycidyl ether, and benzyl alcohol.

[0053] Preferably, in component A, the plasticizer is one or more of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0054] Preferably, in component B, the swelling promoter is one or more of electrospun nanofibers and spiropyran.

[0055] Preferably, in component B, the curing agent is one or more of linoleic acid dimer triethylenetetramine, linoleic acid dimer diethylene, and low molecular weight polyamide.

[0056] Preferably, in component B, the curing accelerator is one or more of DMP-30 and N,N-dimethylethanolamine.

[0057] Furthermore, the watertight adhesive of this invention, when applied to underwater optical cables, fills the gaps in the cable or coats the surface of the cable substrate to improve its longitudinal water pressure resistance. Its application conditions include:

[0058] The preferred mixing ratio of component A to component B is 85–95:10–20, more preferably 90:10. This mixing ratio allows for control of the curing time of the water-tight adhesive. The preferred curing temperature is 15–35°C, more preferably 20–25°C. The preferred curing time is 5–10 hours, more preferably 6–8 hours. Insufficient curing temperature or time will result in incomplete curing, while excessively high temperature or time will also affect the curing effect, thus impacting water pressure resistance.

[0059] Specifically, the preparation process of the watertight adhesive of the present invention is as follows:

[0060] The epoxy resin, expanding monomer, diluent and plasticizer in the specified proportions are mixed evenly to obtain component A;

[0061] Mix the curing agent, curing accelerator and expansion accelerator in a set ratio until homogeneous to obtain component B;

[0062] Before use, mix component A and component B evenly at a mass ratio of 85-95:10-20 to obtain a watertight adhesive.

[0063] In the watertight adhesive of the present invention, the matrix is ​​a two-component epoxy resin. The epoxy resin in component A and the curing agent in component B undergo a curing reaction to form a network three-dimensional polymer. The expanding monomer and other components are encapsulated in the network three-dimensional structure, so that the linear resin becomes a tough three-dimensional polymer. The expanding monomer and accelerator are uniformly distributed therein.

[0064] More preferably, the water-tight adhesive has a water absorption swelling ratio of 150% to 300%, more preferably 200% to 250%. The water absorption swelling ratio is the percentage of the volume expanded after absorbing water to the original volume.

[0065] In the watertight adhesive of the present invention, an expanding monomer is added to induce an expansion effect. The expanding monomer contains hydrophilic groups, which react with hydroxyl groups when they encounter water molecules, locking in the water molecules and increasing the volume to produce an expansion effect. Furthermore, the expanding monomer in component A and the expansion promoter in component B work together. The nanofibers or azide groups of the expansion promoter can form nanopores in the expanding monomer, providing multi-scale water channels for water molecules inside the optical cable. This can connect the isolated resin groups to the matrix surface, thereby enhancing the water absorption and expansion capacity of the material, making its water absorption and expansion ratio between 150% and 300%.

[0066] More preferably, the adhesion strength between the watertight adhesive and the substrate is ≥8 MPa, and more preferably between 9 MPa and 10 MPa. Adhesion strength refers to the tensile force that the adhesive surface can withstand after the watertight adhesive and substrate have bonded and cured. The curing agent and epoxy resin in components A / B have a significant impact on the adhesion strength. Epoxy resin contains various polar groups and highly reactive epoxy groups, which can generate bonding forces with adjacent interfaces of various substrates. During the curing process, epoxy resins react with each other, and under the chemical action of the curing agent, hydroxyl and ether bonds are further generated, resulting in high cohesive and adhesive forces. Simultaneously, under the condition of a matched curing agent, the epoxy groups exhibit good toughness and flexibility when bonding with the substrate, thus achieving high adhesion strength. Under the A / B components and their proportions in this invention, the watertight adhesive exhibits good toughness, and the substrate adhesion strength is ≥8 MPa.

[0067] Furthermore, embodiments of the present invention provide a specific underwater flexible optical cable, such as... Figure 1 As shown, the optical cable structure includes a central reinforcing member 1, an electrical unit 2, an optical unit 3, a wrapping tape 4, a tensile element 5, and an outer sheath 6. The central reinforcing member 1 is preferably a shielded twisted pair. The optical unit 3 and the electrical unit 2 are twisted around the central reinforcing member 1 to form the cable core. The wrapping tape 4 is wrapped around the outside of the cable core, and the tensile element 5 is twisted around the outside of the wrapping tape 4. The outer sheath 6 is the outermost layer and is extruded outside the tensile element 5.

[0068] In some embodiments, the gap between the central reinforcement 1 and the strap 4 is filled with water-tight adhesive; in some embodiments, the gap between the strap 4 and the outer sheath 6 is filled with water-tight adhesive.

[0069] Preferably, the surface of the central reinforcing member 1 is coated with water-tight adhesive; preferably, the surfaces of the optical unit 3 and the electrical unit 2 are coated with water-tight adhesive; preferably, the surfaces of the wrapping tape 4 and the tensile element 5 are coated with water-tight adhesive. Those skilled in the art will understand that as long as the inner surfaces between the central reinforcing member 1 and the wrapping tape 4, the gaps between the optical unit 3 and the electrical unit 2, the inner surfaces between the wrapping tape 4 and the outer sheath 6, and the gaps in the tensile element 5 are all filled with water-tight adhesive, sufficient water-tight adhesive can be ensured in all gaps of the optical cable.

[0070] More preferably, the water-tight adhesive fills more than 90% of the gaps in the optical cable, and more preferably more than 98%. The higher the water-tight adhesive filling rate, the smaller the gaps between the various substrates of the optical cable, and the larger the water absorption and expansion ratio. Once water is absorbed, the water-tight adhesive can expand and fill these gaps.

[0071] The underwater flexible optical cable provided by this invention integrates the optoelectronic unit into one unit, enabling optoelectronic transmission. It also has characteristics such as resistance to radial water pressure and high tensile strength, providing efficient and stable transmission for underwater equipment.

[0072] The underwater flexible optical cable of this invention, while maintaining the high tensile strength and radial underwater performance of the original optical cable, features a water-tight adhesive filling the gaps within the cable. This adhesive expands and fills these gaps after absorbing water. Simultaneously, due to the high bonding strength between the water-tight adhesive and the substrate, the adhesive and substrate do not detach under high water pressure, and the adhesive exhibits high stability under high water pressure. The underwater flexible optical cable using the water-tight adhesive of this invention significantly improves its longitudinal water pressure resistance, protecting equipment at both ends and reducing operational risks in deep water.

[0073] Furthermore, embodiments of the present invention Figure 1 The underwater flexible optical cable shown is manufactured using the following steps:

[0074] The optical unit 3 and the electrical unit 2 are twisted together around the central reinforcing member 1 to form a cable core, and water-tight adhesive is injected during the twisting process.

[0075] Wrap a wrapping tape around the outside of the cable core;

[0076] Tensile element 5 is twisted onto the outside of the strap 4, and watertight adhesive is injected during twisting.

[0077] An outer sheath 6 is extruded onto the outside of the tensile element 5;

[0078] Finally, watertight adhesive is cured to produce an underwater flexible optical cable.

[0079] In a preferred embodiment, before fabrication, a water-tight adhesive is applied to the surface of at least one of the substrates, including the central reinforcement, optical unit, electrical unit, wrapping tape, and tensile element. Alternatively, during fabrication, water-tight adhesive can be applied to the surface of each substrate layer. Those skilled in the art will understand that as long as the inner surfaces between the central reinforcement 1 and the wrapping tape 4, the gaps between the optical unit 3 and the electrical unit 2, the inner surfaces between the wrapping tape 4 and the outer sheath 6, and the gaps in the tensile element 5 are all filled with water-tight adhesive, it is acceptable.

[0080] More preferably, during coating, the temperature of the corresponding substrate (i.e., the central reinforcement, optical unit, electrical unit, wrapping tape, or tensile element) is maintained between 15 and 35°C. Within this range, the curing rate of the watertight adhesive is moderate, providing time for optical cable forming and ensuring complete curing after production. Furthermore, the coating thickness of the watertight adhesive applied to the substrate is preferably greater than 0.5 mm; a thickness greater than this results in higher coating reliability.

[0081] In a preferred embodiment, watertight adhesive is filled into the corresponding substrate gaps (gap between optical and electrical units, gap between tensile elements) using an adhesive injection system. The injection pressure is preferably 0.5 to 1.5 MPa, and the flow rate is controlled by this injection pressure during injection.

[0082] In a preferred embodiment, the watertight adhesive fills at a rate of 90% or more, preferably 98% or more, in the gaps of the optical cable. In actual operation, the greater the coating thickness and the greater the injection pressure, the greater the filling rate.

[0083] In the preferred embodiment, the curing temperature of the watertight adhesive is 15–35°C, more preferably 20–25°C; the curing time is preferably 5–10 hours, more preferably 6–8 hours. Too low a curing temperature or too short a time will result in incomplete curing, while too high a curing temperature or too long a time will also affect the curing effect, thereby affecting the water pressure resistance.

[0084] To better understand the products, applications, and preparation methods of this invention, the following specific embodiments and comparative examples are provided:

[0085] Example 1

[0086] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 10 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0087] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0088] The mass ratio of component A to component B is 90:10. After mixing components A and B, a watertight adhesive is prepared.

[0089] In this embodiment, the method for manufacturing an underwater flexible optical cable includes the following steps:

[0090] One 1.5mm diameter shielded twisted-pair cable, four 1.2mm optical fiber units, and four 0.6mm diameter optical fiber units are used. 2 The electrical unit 2 is placed on the pay-off frame, with a pay-off tension of 5N, and is then stranded by a stranding machine to form the cable core. During stranding, the prepared watertight adhesive is filled through an adhesive injection system at a pressure of 0.5MPa.

[0091] A layer of non-woven fabric tape 4 with a thickness of 0.25 mm and a width of 10 mm is wrapped around the cable core, and then placed on the pay-off frame with a pay-off tension of 20 N. 24 strands of 3220 dtex aramid (tensile element 5) are twisted around the tape 4. When the aramid is twisted, the prepared watertight adhesive is filled through the glue injection system with a glue injection pressure of 0.6 MPa.

[0092] After injection, the material enters the extruder via guide rollers for extrusion molding of the outer sheath 6. The extruder is configured with the following zones from the feed inlet to the die opening: feed inlet, barrel zone 1, barrel zone 2, barrel zone 3, barrel zone 4, barrel zone 5, neck, and die opening. The temperatures of each zone are set as follows: feed inlet 150±5℃, barrel zone 1 165±10℃, barrel zone 2 180±10℃, barrel zone 3 195±10℃, barrel zone 4 195±10℃, barrel zone 5 205±10℃, and neck and die opening 205±10℃. The cooling area at the die opening outlet adopts segmented cooling. The first segment connected to the die opening uses a warm water cooling tank with a cooling temperature of 50±10℃, while the remaining segments use room temperature water cooling.

[0093] Finally, the watertight adhesive is cured at a temperature of 15–35°C for 5–10 hours to produce an underwater flexible optical cable.

[0094] Example 2

[0095] In this embodiment, the formulation of component A by weight is as follows: 85 parts of bisphenol A epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0096] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0097] The mixing mass ratio of component A to component B is 90:10.

[0098] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0099] Example 3

[0100] In this embodiment, the formulation of component A by weight is as follows: 80 parts of bisphenol A epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0101] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of swelling accelerator.

[0102] The mixing mass ratio of component A to component B is 90:10.

[0103] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0104] Example 4

[0105] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0106] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0107] The mixing mass ratio of component A to component B is 90:10.

[0108] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0109] Example 5

[0110] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 15 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0111] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0112] The mixing ratio of component A to component B is 90:10.

[0113] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0114] Example 6

[0115] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 10 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0116] The formula for component B, by weight, is: 50 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0117] The mixing mass ratio of component A to component B is 90:10.

[0118] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0119] Example 7

[0120] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol F epoxy resin, 10 parts of TPE / P (AA-co-AM) water-absorbing and swelling monomer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0121] The formula for component B, by weight, is: 60 parts of linoleic acid dimer triethylenetetramine, 15 parts of DMP-30, and 20 parts of spiropyran.

[0122] The mixing mass ratio of component A to component B is 90:10.

[0123] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0124] Example 8

[0125] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol F epoxy resin, 10 parts of sodium nano polyacrylate, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0126] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of DMP-30, and 10 parts of spiropyran.

[0127] The mixing mass ratio of component A to component B is 90:10.

[0128] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0129] Example 9

[0130] In this embodiment, the formulation of component A by weight is: 70 parts phenolic epoxy resin, 10 parts polyurethane prepolymer, 30 parts ethylene glycol diglycidyl ether, and 15 parts dimethyl phthalate.

[0131] The formula for component B, by weight, is: 55 parts linoleic acid dimer diethylene, 15 parts DMP-30, and 15 parts spiropyran.

[0132] The mixing mass ratio of component A to component B is 90:10.

[0133] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0134] Example 10

[0135] In this embodiment, the formulation of component A by weight is as follows: 70 parts of alicyclic epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 20 parts of ethylene glycol diglycidyl ether, and 10 parts of dimethyl phthalate.

[0136] The formulation of component B by weight is: 55 parts low molecular weight polyamide, 15 parts N,N-dimethylethanolamine, and 20 parts spiropyran.

[0137] The mixing mass ratio of component A to component B is 95:10.

[0138] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0139] Example 11

[0140] In this embodiment, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 40 parts of ethylene glycol diglycidyl ether, and 20 parts of dimethyl phthalate.

[0141] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of spiropyran.

[0142] The mixing mass ratio of component A to component B is 85:20.

[0143] In this embodiment, the method for manufacturing the underwater flexible optical cable is the same as in Embodiment 1.

[0144] Comparative Example 1

[0145] In this comparative example, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 5 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0146] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 5 parts of electrospun nanofibers.

[0147] The mixing mass ratio of component A to component B is 90:10.

[0148] In this comparative example, the method for manufacturing the underwater flexible optical cable is the same as in Example 1.

[0149] Comparative Example 2

[0150] In this comparative example, the formulation of component A by weight is as follows: 70 parts of bisphenol A epoxy resin, 20 parts of methacrylic acid-ethyl acetate copolymer, 30 parts of ethylene glycol diglycidyl ether, and 15 parts of dimethyl phthalate.

[0151] The formula for component B, by weight, is: 55 parts of linoleic acid dimer triethylenetetramine, 15 parts of N,N-dimethylethanolamine, and 20 parts of electrospun nanofibers.

[0152] The mixing mass ratio of component A to component B is 95:5.

[0153] In this comparative example, the method for manufacturing the underwater flexible optical cable is the same as in Example 1.

[0154] The underwater flexible optical cables prepared in the above embodiments and comparative examples were subjected to performance testing. The testing method was as follows:

[0155] The fill rate test method is as follows: microscopic imaging measurement is performed by longitudinally cutting five optical cable interfaces spaced 5 cm apart.

[0156] The water absorption swelling ratio test method is as follows: the water absorption swelling ratio is the percentage of the volume expanded after water absorption to the original volume. Take two portions of the cured water-tight adhesive, each 100g. Soak one portion in water for 24 hours to fully absorb water and expand. Compare the expanded volume after water absorption with the original volume.

[0157] The longitudinal water pressure test method is as follows: one end of the watertight optical cable is placed in the water pressure tank and sealed with a silicone sheet, while the other end is placed outside the water pressure tank. The water pressure in the water pressure tank is increased to a fixed pressure and maintained. A humidity test strip is used to observe whether the optical cable placed outside the water pressure tank leaks water.

[0158] The water pressure resistance test results of the underwater flexible optical cables fabricated in the above embodiments and comparative examples are shown in the table below:

[0159]

[0160] The underwater optical cables filled with watertight adhesive produced in this embodiment of the invention, as shown in the above results, did not leak under 8MPa water pressure in Examples 1 to 11, while Comparative Example 1 leaked immediately, and Comparative Example 2 leaked after 6 hours. Because the watertight adhesive formulation in the examples is within a reasonable range, it has a very good water absorption-swelling ratio and can block 8MPa water pressure. In contrast, in the comparative examples, due to the lack of a suitable ratio of swelling monomers and swelling promoters, the water absorption-swelling was limited under 8MPa water pressure, and it could not block or sustainably block water pressure. This indicates that the underwater flexible optical cable prepared in this embodiment has a significant longitudinal water-blocking effect of the watertight adhesive, which significantly improves the water pressure resistance of the underwater flexible optical cable.

[0161] Those skilled in the art will readily understand 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 within the scope of protection of the present invention.

Claims

1. A watertight adhesive, characterized in that, By weight, it includes the following ingredients: Component A: 70-85 parts epoxy resin, 10-20 parts expanded monomer, 20-40 parts diluent, and 10-20 parts plasticizer; Component B: 50-60 parts curing agent, 10-20 parts curing accelerator, 10-20 parts expansion accelerator; The mass ratio of component A to component B is 85~95:10~20; The expanding monomer includes one or more of the following: TPE / P (AA-co-AM) water-absorbing and expanding monomer, nano-sodium polyacrylate, methacrylate-ethyl acetate copolymer, and polyurethane prepolymer. The swelling promoter is one or more of electrospun nanofibers and spiropyran; The water-tight adhesive has a water absorption swelling ratio of 150% to 300%, and the bonding strength between the water-tight adhesive and the substrate is ≥8MPa; The epoxy resin includes one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and alicyclic epoxy resin; The diluent is ethylene glycol diglycidyl ether; The plasticizer is dimethyl phthalate; The curing agent is one or more of the following: linoleic acid dimer triethylenetetramine, linoleic acid dimer diethylene, and low molecular weight polyamide; The curing accelerator is one or more of DMP-30 and N,N-dimethylethanolamine.

2. The watertight adhesive according to claim 1, characterized in that, The water-tight adhesive has a water absorption and swelling ratio of 200%~250%; and / or, The bonding strength between the watertight adhesive and the substrate is 9 MPa to 10 MPa.

3. An application of the watertight adhesive as described in claim 1 or 2 in underwater optical cables, characterized in that, Its application conditions include: The curing temperature is 15~35℃, and the curing time is 5~10h.

4. The application of the watertight adhesive as described in claim 3 in underwater optical cables, characterized in that, The watertight adhesive has a filling rate of over 90% in the optical cable gaps.

5. An underwater flexible optical cable, employing the watertight adhesive as described in claim 1 or 2, characterized in that, The optical cable structure includes a central reinforcing member, electrical units, optical units, wrapping tape, tensile elements, and an outer sheath; among which, The optical unit and the electrical unit are twisted together around the central reinforcing member to form a cable core; the wrapping tape is wrapped around the outside of the cable core, and the tensile element is twisted around the outside of the wrapping tape; the outer sheath is located on the outermost layer and is extruded outside the tensile element; The gap between the central reinforcement and the strap is filled with water-tight adhesive; and / or, the gap between the strap and the outer sheath is filled with water-tight adhesive.

6. The underwater flexible optical cable according to claim 5, characterized in that, The surface of the central reinforcing member is coated with water-tight adhesive; and / or, the surfaces of the optical unit and the electrical unit are coated with water-tight adhesive; and / or, the surfaces of the strap and the tensile element are coated with water-tight adhesive.

7. A method for manufacturing an underwater flexible optical cable, used to manufacture the underwater flexible optical cable as described in claim 5 or 6, characterized in that, Includes the following steps: The optical unit and the electrical unit are twisted together around the central reinforcing member to form a cable core, and water-tight adhesive is injected during the twisting process. Wrap a wrapping tape around the outside of the cable core; Tensile-resistant elements are twisted together on the outside of the strapping, and watertight adhesive is injected during twisting. An outer sheath is extruded onto the outside of the tensile element; Finally, watertight adhesive is cured to produce an underwater flexible optical cable.

8. The method for manufacturing an underwater flexible optical cable according to claim 7, characterized in that, Before fabrication, a water-tight adhesive is applied to the surface of at least one of the substrates, including the central reinforcing member, optical unit, electrical unit, wrapping tape, and tensile element; or, during fabrication, a water-tight adhesive is applied to the surface of each substrate layer. During application, the corresponding substrate temperature is maintained between 15 and 35°C, and the coating thickness is greater than 0.5 mm. When injecting watertight adhesive, the injection pressure is 0.5~1.5MPa.

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