Pressure-sensitive adhesive for optical cable and optical cable

Abstract

The embodiment of the invention provides a pressure-sensitive adhesive for an optical cable, the pressure-sensitive adhesive is used for being arranged on the outer surface of a sheath of the optical cable, the pressure-sensitive adhesive comprises a main body resin, a cross-linking agent, a nano inorganic flame retardant, a phosphate flame retardant and a tackifier, the main body resin at least comprises a polymer with a cross-linkable group, and the cross-linking agent is a polymer with a cross-linkable group. The polymer and the cross-linking agent are used for enabling the pressure-sensitive adhesive to form a cross-linked network structure; the visible light transmittance of the pressure-sensitive adhesive is 10% or above. The pressure-sensitive adhesive has good transparency, flame retardance, adhesion and the like, so that the optical cable is good in invisible effect and good in laying reliability. The embodiment of the invention also provides an optical cable.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of indoor optical cables, and particularly to a pressure-sensitive adhesive for optical cables and an optical cable. Background Art

[0002] With the advent of the 5G era of Internet of Everything, people have put forward higher requirements for home network networking. FTTR (Fiber to the Room) is a new coverage mode for home networks, which can lay indoor optical cables into each room of users to ensure high network speed in each room.

[0003] The optical cables used in FTTR scenarios usually include optical fibers, optical fibers embedded in a sheath, and an adhesive layer provided on the sheath. To ensure good fire safety of the optical cable, it is required that the adhesive layer used for the optical cable should have good flame retardancy. However, the transparency of the adhesive layer with good flame retardancy is usually poor, resulting in poor invisibility effect of the optical cable. Summary of the Invention

[0004] In view of this, the embodiments of the present application provide a pressure-sensitive adhesive for optical cables to solve the problem that the existing adhesive layer for optical cables cannot take into account both good transparency and flame retardancy.

[0005] Specifically, in the first aspect of the embodiments of the present application, a pressure-sensitive adhesive for optical cables is provided, which is used to be disposed on the outer surface of the sheath of the optical cable. The pressure-sensitive adhesive includes a main resin, a cross-linking agent, a nano-inorganic flame retardant, a phosphate flame retardant, and a tackifier. Among them, the main resin at least includes a polymer with cross-linkable groups, and the polymer and the cross-linking agent are used to form a cross-linked network structure of the pressure-sensitive adhesive; the visible light transmittance of the pressure-sensitive adhesive is above 10%.

[0006] By introducing a nano-inorganic flame retardant and a phosphate flame retardant into the pressure-sensitive adhesive at the same time, the flame retardant performance of the pressure-sensitive adhesive can be guaranteed to be excellent. At the same time, the phosphate flame retardant can promote the compatibility between the nano-inorganic flame retardant and the main resin, and the above cross-linked network structure of the pressure-sensitive adhesive can reduce the precipitation of the nano-inorganic flame retardant. Furthermore, the visible light transmittance of the pressure-sensitive adhesive is still relatively high, and the bonding reliability is high.

[0007] In the embodiments of the present application, the peak heat release rate of the pressure-sensitive adhesive is less than or equal to 600 kW / m 2 . This reflects that the pressure-sensitive adhesive of the present application has good flame retardancy.

[0008] In some embodiments of the present application, the visible light transmittance of the pressure-sensitive adhesive is above 50%, and the peak heat release rate is less than or equal to 400 kW / m 2 . In this case, the pressure-sensitive adhesive can better balance high transparency and excellent flame retardancy.

[0009] In the embodiments of the present application, the softening point of the pressure-sensitive adhesive is between 100 and 125 °C. The relatively high softening point can reflect that the pressure-sensitive adhesive of the present application has good thermal stability and is not prone to creep.

[0010] In the embodiments of the present application, the peeling force of the adhesive layer formed by the pressure-sensitive adhesive on the polyethylene terephthalate film is greater than or equal to 0.4 N / m. In the case where the pressure-sensitive adhesive of the embodiments of the present application contains a nano-inorganic flame retardant, its adhesiveness is still good, and the polyethylene terephthalate film is not easily peeled off from the pressure-sensitive adhesive layer.

[0011] In the embodiments of the present application, the total mass ratio of the nano-inorganic flame retardant and the phosphate ester flame retardant in the pressure-sensitive adhesive is 5-40%. Controlling the sum of the mass ratios of these two flame retardants, namely the nano-inorganic flame retardant and the phosphate ester flame retardant, within this range is conducive to ensuring good flame retardancy and transparency of the pressure-sensitive adhesive.

[0012] In the embodiments of the present application, the mass ratio of the nano-inorganic flame retardant to the phosphate ester flame retardant is (0.2-1.2):1. Applying these two flame retardants to the above-mentioned pressure-sensitive adhesive in such a mass ratio is more conducive to the two of them exerting a synergistic flame retardant effect and more conducive to the uniform dispersion of the nano-inorganic flame retardant in the pressure-sensitive adhesive.

[0013] In the embodiments of the present application, the mass ratio of the nano-inorganic flame retardant in the pressure-sensitive adhesive is 5-20%. When both the nano-inorganic flame retardant and the phosphate ester flame retardant are present in the above-mentioned pressure-sensitive adhesive, the mass ratio of the former within this range is more conducive to the pressure-sensitive adhesive having good transparency and its flame retardant performance not being too weak.

[0014] In the embodiments of the present application, the size of the nano-inorganic flame retardant is between 1 nm and 500 nm. The relatively small size of the inorganic flame retardant is more conducive to its good dispersion in the pressure-sensitive adhesive system, ensuring relatively high transparency and good adhesion of the pressure-sensitive adhesive.

[0015] In the embodiments of the present application, the nano-inorganic flame retardant includes one or more of aluminum phosphate, zinc phosphate, aluminum hypophosphite, zinc oxide; the phosphate ester flame retardant includes one or more of cetyl phosphate, octadecyl phosphate, tetraphenylbisphenol A diphosphate, bisphenol A bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), cyclic phosphate, triethyl phosphate. These phosphate ester flame retardants have relatively good flame retardant properties, and in the presence of these phosphate ester flame retardants, the dispersion properties of the above-mentioned inorganic flame retardant in the pressure-sensitive adhesive system are better.

[0016] In the embodiments of the present application, the crosslinkable group includes one or more of epoxy group, carboxyl group, sulfonic acid group, hydroxyl group, amino group.

[0017] In some embodiments of the present application, the crosslinkable group includes a carboxyl group and / or a sulfonic acid group, and the crosslinking agent includes a metal salt; wherein, the metal ion in the metal salt can form a non-covalent ionic bond with the carboxyl group and / or the sulfonic acid group. The ionic crosslinking bond can ensure that the pressure-sensitive adhesive maintains a good network structure at a moderately high temperature, has good thermal stability, and at a higher temperature, the ionic crosslinking bond can dissociate, facilitating the reprocessing and coating of the pressure-sensitive adhesive.

[0018] In an embodiment of the present application, the metal ion in the metal salt includes one of zinc ions, magnesium ions, iron ions, cobalt ions, and manganese ions.

[0019] In an embodiment of the present application, the total mass ratio of the crosslinking agent in the pressure-sensitive adhesive is 0.2% - 10%. The addition of an appropriate amount of the crosslinking agent can endow the pressure-sensitive adhesive with a moderately crosslinked network structure, giving it good thermal stability, and at the same time, it will not reduce the adhesion performance and optical properties of the pressure-sensitive adhesive due to excessive content of the crosslinking agent.

[0020] In some embodiments of the present application, the main resin further includes a resin without a crosslinkable group. In this case, the pressure-sensitive adhesive contains two types of main resins at the same time, and its mechanical properties are relatively excellent, especially with better elasticity.

[0021] In some embodiments of the present application, the mass ratio of the polymer with a crosslinkable group in the pressure-sensitive adhesive is 1% - 20%, and the mass ratio of the resin without a crosslinkable group in the pressure-sensitive adhesive is 10% - 60%. By regulating the mass ratios of these two main resins in the pressure-sensitive adhesive, comprehensive regulation of the thermal stability, elasticity, adhesiveness, transparency, etc. of the pressure-sensitive adhesive can be achieved.

[0022] In an embodiment of the present application, the total mass ratio of the main resin in the pressure-sensitive adhesive is 30% - 70%. Controlling the total mass ratio of the main resin in the pressure-sensitive adhesive within the above range is beneficial to the good dispersion of the above two types of flame retardants in the system, making the pressure-sensitive adhesive have high transparency and good adhesiveness.

[0023] In an embodiment of the present application, by weight, the pressure-sensitive adhesive includes the following raw materials: 32 - 70 parts of main resin; 0.5 - 3 parts of crosslinking agent; 5 - 15 parts of nano-inorganic flame retardant; 5 - 30 parts of phosphate flame retardant; 20 - 150 parts of tackifier; 0 - 100 parts of softening oil; 0 - 2 parts of auxiliary agent. By reasonably adjusting the raw materials and their ratios for forming the pressure-sensitive adhesive, it is possible to achieve that the pressure-sensitive adhesive has good transparency, flame retardancy, adhesiveness, thermal stability, etc.

[0024] In a second aspect of the embodiments of the present application, an optical cable is provided. The optical cable includes a sheath, an optical fiber, and an adhesive layer. Among them, the optical fiber is located inside the sheath, and the adhesive layer is provided on at least a part of the outer surface of the sheath. The adhesive layer uses the pressure-sensitive adhesive described in the first aspect of the embodiments of the present application. Due to the use of the above-mentioned pressure-sensitive adhesive with high transparency, good flame retardancy, and excellent mechanical properties in the adhesive layer of the optical cable, the optical cable has good invisibility effect, good fire resistance, and high laying reliability.

[0025] In the embodiments of the present application, the thickness of the adhesive layer is 50 - 600 μm. An appropriate thickness of the adhesive layer can make its adhesiveness more reliable.

[0026] In the embodiments of the present application, the fire protection grade of the optical cable is above Eca grade. Since the adhesive layer of the optical cable uses the above-mentioned pressure-sensitive adhesive with good flame retardancy, the fire resistance of the optical cable is also relatively good.

[0027] In some embodiments of the present application, the optical cable further includes a release film; the release film is provided on the surface of the adhesive layer. The release film can protect the adhesive layer and can be removed before installing the optical cable.

[0028] In the embodiments of the present application, the optical fiber is a single-core optical fiber or a multi-core optical fiber.

[0029] In some embodiments of the present application, the optical cable further includes a wire, and the wire is located inside the sheath. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A FIG. is a schematic three-dimensional structure diagram of an optical cable.

[0031] Figure 1B For Figure 1A A side view of the optical cable shown.

[0032] Figure 1C FIG. is another schematic structure diagram of the optical cable shown in the embodiments of the present application.

[0033] Figure 2 FIG. is still another schematic structure diagram of the optical cable shown in the embodiments of the present application.

[0034] Figure 3 FIG. is still another schematic structure diagram of the optical cable shown in the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will describe the embodiments of the present application in conjunction with the drawings in the embodiments of the present application.

[0036] In the FTTR solution, the optical cable between the main optical network terminal installed in the home and the distribution box in each room can be used for optical signal transmission between the two, thus ensuring that there is a stable network point in each room. Please refer to Figure 1A and Figure 1B , embodiments of the present application provide an optical cable. Among them, Figure 1A is a three-dimensional structure schematic diagram of the optical cable, Figure 1B is Figure 1A a side view of the optical cable shown.

[0037] The optical cable 100 includes a sheath 10, an optical fiber 20, and an adhesive layer 30. Among them, the optical fiber 20 is located inside the sheath 10, and the adhesive layer 30 is disposed on at least part of the surface of the sheath 10. The optical fiber 20 is used for transmitting optical signals. For example, after the optical cable 100 is connected to the main optical network terminal in the home and the distribution box in each room, the optical fiber 20 in the optical cable realizes signal transmission between the main optical network terminal and the distribution box. Among them, the optical fiber in the optical cable 100 can be a single-core optical fiber or a multi-core optical fiber. Figure 1A , Figure 1B At the position numbered 20 in

[0038] a single optical fiber is placed to achieve single-core communication. In other ways of the present application, if multiple optical fibers can also be placed in the sheath 10 to achieve multi-core communication.

[0039] The sheath 10 is used to wrap the optical fiber 20, etc., and can isolate the optical fiber 20 from the external environment, playing a role in protecting the optical fiber 20 and preventing the optical fiber 20 from being damaged due to collisions with the external environment during handling or installation. When installing the optical cable 100, part of the sheath 10 around the end of the optical fiber 20 can be torn off to expose the end of the optical fiber 20, and then the optical fiber 20 can be fusion-spliced or connected to an FMC connector, and then connected to the distribution box and the main optical network terminal, etc. In some other cases, prefabricated connectors can be directly provided at both ends of the optical fiber 20 in the optical cable 100. In this way, when installing the optical cable, part of the sheath 10 around the end of the optical fiber 20 is torn off to expose the prefabricated connector at the end of the main optical fiber 20, and finally the prefabricated connector is connected to the distribution box, etc. Figure 1A and Figure 1B take the example that the adhesive layer 30 is disposed on a part of the lower surface of the sheath 10. It can be understood that the extension width of the adhesive layer 30 (i.e., the length along the x-axis direction in the figure) can be less than or equal to the extension width of the sheath 10. Figure 1A and Figure 1BIn the example, the extended width of the adhesive layer 30 is slightly smaller than that of the sheath 10. In addition, to provide the bonding reliability of the optical cable, at least a part of the outer surface of the sheath 10 is configured as a flat surface, and the adhesive layer 30 is disposed on this flat surface. So as to stably fix the adhesive layer 30 on the outer surface of the sheath 10, and at the same time enable the sheath 10 to be stably fixed on the wall through the horizontal adhesive layer 30.

[0040] Among them, the adhesive layer 30 can be a pressure-sensitive adhesive layer or a hot-melt adhesive layer, and the pressure-sensitive adhesive layer is more common. If the adhesive layer 30 is a pressure-sensitive adhesive layer, during the installation process of the optical cable, the sheath 10 can be bonded to the wall of the optical cable to be installed by pressing the pressure-sensitive adhesive layer to make it sticky. However, the pressure-sensitive adhesive used for the adhesive layer 30 cannot take into account both good transparency and flame retardancy. If the transparency of the pressure-sensitive adhesive is too low, the invisibility effect of the optical cable 100 will be poor and the aesthetics will be affected, and it cannot adapt to different home decoration styles; if the pressure-sensitive adhesive is basically non-flammable or has too poor flame retardancy, it will cause the optical cable not to meet the indoor fire safety requirements, and an open flame will damage the sheath, optical fiber, etc. of the optical cable. Based on this, the embodiment of the present application provides a pressure-sensitive adhesive that can be used for the adhesive layer 30 in the optical cable, so that the adhesive layer 30 takes into account both good transparency and flame retardancy.

[0041] Specifically, the adhesive layer 30 in the optical cable 100 is specifically a pressure-sensitive adhesive layer, and can be formed by using the following pressure-sensitive adhesive in the embodiment of the present application. The pressure-sensitive adhesive includes a main resin, a cross-linking agent, a nano-inorganic flame retardant, a phosphate flame retardant, and a tackifier. Among them, the main resin at least includes a polymer with a cross-linkable group, and the polymer and the cross-linking agent are used to form a cross-linked network structure for the pressure-sensitive adhesive; the visible light transmittance (that is, "transparency") of the pressure-sensitive adhesive is above 10%.

[0042] In the above-mentioned pressure-sensitive adhesive, a nano-scale inorganic flame retardant with a small size and an organic flame retardant, a phosphate flame retardant, are introduced simultaneously. The coexistence of these two types of flame retardants can ensure excellent flame retardancy of the pressure-sensitive adhesive, enabling the optical cable using this pressure-sensitive adhesive to better meet the indoor flame retardancy requirements. Second, the size of the inorganic nano flame retardant is small, which has little impact on the transparency of the pressure-sensitive adhesive. Moreover, the phosphate flame retardant has good compatibility with the main resin in the system. It can establish a compatible bridge between the nano-inorganic flame retardant and the main resin, prevent the precipitation of the powdery inorganic flame retardant, ensure its uniform dispersion in the pressure-sensitive adhesive, and the cross-linked network structure formed by the polymer with cross-linkable groups and the cross-linking agent can also play a good binding role on the flame retardant, helping to reduce the aggregation and precipitation of the flame retardant, and thus not affecting the transparency (visible light transmittance can be above 10%) and adhesiveness of the pressure-sensitive adhesive. In addition, the cross-linked network structure formed by the interaction between the polymer with cross-linkable groups and the cross-linking agent can also make the pressure-sensitive adhesive have good thermal stability, not easy to creep, and high bonding reliability. Therefore, the pressure-sensitive adhesive provided by the embodiments of the present application can take into account good flame retardancy, transparency, adhesiveness and stability, and has high application aesthetics and reliability.

[0043] For "the polymer and the cross-linking agent are used to form a cross-linked network structure", specifically, it can be: the polymer forms a covalent cross-linking bond or a non-covalent cross-linking bond with the cross-linking agent through its cross-linkable groups, so that the pressure-sensitive adhesive has a cross-linked network structure. Among them, the non-covalent cross-linking bond can be, for example, an ionic bond, and the formed ionic bond can be dissociated again under certain conditions. In the present application, the above-mentioned term "creep" refers to the phenomenon that the strain of a solid material increases with time under the condition of maintaining a constant stress.

[0044] In the present application, the term "visible light transmittance" refers to the percentage of visible light passing through the surface of an object in a certain environment. This parameter can reflect the appearance, transparency, etc. of the article. Among them, the visible light transmittance can be measured in the following way: stick a pressure-sensitive adhesive layer with a thickness of 20-50 μm formed by the above-mentioned pressure-sensitive adhesive on optical glass, and use a spectrocolorimeter to measure its light transmittance to visible light. In the present application, the visible light transmittance of the pressure-sensitive adhesive can be above 20%, above 30%, above 40%, above 45%, above 50%, above 55%, above 60%, above 66%, above 70%, above 75%, above 80%, above 85% or above 90%, etc. In some embodiments of the present application, the visible light transmittance of the pressure-sensitive adhesive is above 50%. A higher visible light transmittance of the pressure-sensitive adhesive means higher transparency, which is beneficial for it to meet the requirements of the optical cable for invisibility. In some embodiments, the visible light transmittance of the pressure-sensitive adhesive is 50%-85%. In this case, the flame retardancy of the pressure-sensitive adhesive will also be better.

[0045] In the embodiments of the present application, the peak of the heat release rate (PHRR) of the pressure-sensitive adhesive is less than or equal to 600 kW / m 2 . The PHRR is the maximum value of the heat release rate of the material during the entire combustion period. The magnitude of the PHRR represents the maximum degree of heat release during the combustion of the material. The smaller its value, the less heat is released during the combustion of the material, and the smaller the fire hazard formed. The PHRR can be measured by a cone-type cone calorimeter on a pressure-sensitive adhesive sample of a certain shape (a cube with a thickness of 3 mm and a length × width of 100 mm × 100 mm), and the test standard is Specifically, the peak of the heat release rate of the pressure-sensitive adhesive is less than or equal to 500 kW / m 2 , or less than or equal to 400 kW / m 2 , or less than or equal to 300 kW / m 2 , or less than or equal to 250 kW / m 2 and so on.

[0046] In some embodiments of the present application, the visible light transmittance of the pressure-sensitive adhesive is above 50%, and the peak of the heat release rate is less than or equal to 400 kW / m 2 . This reflects that the pressure-sensitive adhesive can better balance good transparency and flame retardancy.

[0047] In the embodiments of the present application, the softening point of the pressure-sensitive adhesive is above 100 °C. Further, it can be above 110 °C. The term "softening point" refers to the temperature at which a substance softens, mainly referring to the temperature at which the substance begins to soften. The softening point of the pressure-sensitive adhesive in the embodiments of the present application is at a moderately high temperature, which can reflect that the pressure-sensitive adhesive has good thermal stability. In some embodiments of the present application, the softening point of the pressure-sensitive adhesive is between 110-125 °C. In this case, the pressure-sensitive adhesive can better maintain its cross-linked network structure below 100 °C, and is not easily creeped to cause a decrease in its adhesion, and has high thermal stability. At the same time, the pressure-sensitive adhesive can also have a certain reprocessing ability at high temperatures, which is convenient for application.

[0048] In the embodiments of the present application, the peeling force of the adhesive layer formed by the pressure-sensitive adhesive on a polyethylene terephthalate (PET) film is greater than or equal to 0.4 N / m. The pressure-sensitive adhesive layer shows a strong peeling force on PET, indicating its good adhesion performance, which can better achieve the adhesion between the cable sheath and the wall, and prevent the installed cable from falling off the wall. In the case where the pressure-sensitive adhesive of the embodiments of the present application contains a nano-inorganic flame retardant, its adhesiveness is still good, which also shows to a certain extent that the above nano-inorganic flame retardant can be fully dispersed in the system. In some embodiments of the present application, the peeling force of the adhesive layer formed by the pressure-sensitive adhesive on the PET film is greater than or equal to 0.5 N / m, or greater than or equal to 0.6 N / m, or greater than or equal to 0.7 N / m, or greater than or equal to 0.8 N / m, or greater than or equal to 0.9 N / m, etc. In some embodiments, the peeling force of the adhesive layer formed by the pressure-sensitive adhesive on the PET film is between 0.4 N / m and 0.8 N / m. In this case, the pressure-sensitive adhesive can also have a high visible light transmittance and flame retardancy.

[0049] Among them, the above peeling force can be tested by the following method: First, heat the pressure-sensitive adhesive to 180 °C to make it have good fluidity, then coat the pressure-sensitive adhesive on a steel plate, and quickly bond a PET film (about 50 μm thick) on the pressure-sensitive adhesive. After cooling, a pressure-sensitive adhesive layer with a thickness of 50 μm is formed between the steel plate and the PET film. At room temperature of 25 °C, use a tensile machine to peel the PET film to test the peeling force of the pressure-sensitive adhesive layer on PET.

[0050] In the above pressure-sensitive adhesive of the embodiments of the present application, when it contains both a nano-inorganic flame retardant and a phosphate flame retardant, its elastic properties are still good. Among them, the Young's modulus of the pressure-sensitive adhesive can be in the range of 20 - 1000 MPa.

[0051] In the embodiments of the present application, the size of the nano-inorganic flame retardant can be between 1 nm and 500 nm. Exemplarily, the size of the nano-inorganic flame retardant can be specifically 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, etc. In some embodiments, the size of the nano-inorganic flame retardant can be 1 nm - 200 nm, 1 nm - 100 nm, 5 nm - 200 nm, or 5 nm - 100 nm, etc. The nano-inorganic flame retardant with a smaller size is more conducive to achieving a good dispersion effect in the pressure-sensitive adhesive system, ensuring that the pressure-sensitive adhesive has a higher transparency and better adhesion.

[0052] In the embodiments of the present application, the nano-inorganic flame retardant includes aluminum phosphate (chemical formula: AlPO 4) Zinc phosphate (chemical formula: Zn 3 (PO 4 ) 2 ) Aluminum hypophosphite (chemical formula: Al(H 2 PO 2 ) 3 ) Zinc oxide (chemical formula: ZnO), etc., one or more of them, but not limited to these. These inorganic flame retardants have excellent flame retardant properties. In particular, aluminum phosphate, zinc phosphate, and aluminum hypophosphite are all inorganic flame retardants containing phosphorus elements, and they have better compatibility with phosphate ester flame retardants containing the same phosphorus element, so that they can be better dispersed in the pressure-sensitive adhesive system.

[0053] In the embodiments of the present application, the phosphate ester flame retardant may include, but is not limited to, one or more of cetyl phosphate, octadecyl phosphate, tetraphenyl bisphenol A diphosphate, bisphenol A bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), triethyl phosphate, and cyclic phosphate.

[0054] In the embodiments of the present application, the total mass ratio of the nano-inorganic flame retardant and the phosphate ester flame retardant in the pressure-sensitive adhesive is 5-40%. When the nano-inorganic flame retardant and the phosphate ester flame retardant coexist in the above-mentioned pressure-sensitive adhesive, the total mass ratio within this range is beneficial to ensuring that the pressure-sensitive adhesive has good flame retardancy and transparency. Specifically, the total mass ratio may be specifically 10%, 12%, 15%, 16%, 17%, 18%, 20%, 25%, 28%, 30%, 36%, etc. In some embodiments, the total mass ratio is 10%-40%. Within this range of the total mass ratio, these two flame retardants are not easily precipitated, the transparency of the pressure-sensitive adhesive is higher, the adhesiveness is higher, and at the same time, the pressure-sensitive adhesive has good flame retardancy.

[0055] In the embodiments of the present application, the mass ratio of the nano-inorganic flame retardant to the phosphate ester flame retardant may be (0.2-1.2):1. In this case, it is more conducive to the two flame retardants to exert a synergistic flame retardant effect, and the solid nano-inorganic flame retardant has better compatibility with organic substances such as matrix resin and tackifier in the pressure-sensitive adhesive by virtue of the phosphate ester flame retardant, ensuring higher transparency of the pressure-sensitive adhesive under the same flame retardant effect; or ensuring better flame retardancy of the pressure-sensitive adhesive under the same transparency. Specifically, the mass ratio is, for example, 0.3:1, 0.5:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.15:1, 1.2:1, etc. In some embodiments, the mass ratio is (0.5-1.2):1.

[0056] In the embodiments of the present application, in the case where both the nano-inorganic flame retardant and the phosphate ester flame retardant are present in the above-mentioned pressure-sensitive adhesive, the mass ratio of the nano-inorganic flame retardant in the pressure-sensitive adhesive can be below 30%, and the pressure-sensitive adhesive can still have good transparency. In some embodiments of the present application, the mass ratio of the nano-inorganic flame retardant in the pressure-sensitive adhesive can be 5-20%, for example, specifically 6%, 7%, 8%, 10%, 12%, 15%, etc., and further can be in the range of 5-10%. The mass ratio of the phosphate ester flame retardant in the pressure-sensitive adhesive can be 5-20%, for example, specifically 6%, 7%, 8%, 10%, 12%, 15%, etc., and further can be in the range of 5-10%.

[0057] In the embodiments of the present application, in the polymer with crosslinkable groups, the crosslinkable groups can include one or more of epoxy groups, carboxyl groups (-COOH), sulfonic acid groups (-SO 3 H), hydroxyl groups (-OH), and amino groups, but are not limited thereto. Among them, the amino group should be understood in a broad sense and can be a primary amino group (-NH 2 ), or a secondary amino group (-NHR, where R can be a substituted or unsubstituted alkyl or aryl group), etc. In some embodiments, the polymer with crosslinkable groups can be a styrene block copolymer with crosslinkable groups, for example, a carboxyl-modified styrene block copolymer (such as a maleic anhydride-modified styrene block copolymer).

[0058] In some embodiments of the present application, the crosslinking agent can form a covalent crosslinking bond with the polymer with crosslinkable groups. In this case, the crosslinking agent has at least two corresponding reactive groups that can react with the crosslinkable polar groups. Among them, the crosslinked network structure with covalent crosslinking bonds has better thermal stability.

[0059] Among them, when the crosslinkable group is an epoxy group, the crosslinking agent that can form a covalent bond with the polymer with crosslinkable groups includes one or more of substances having at least two amino groups in the molecular structure, substances having at least two carboxyl groups, and acid anhydride substances. That is, the crosslinking agent includes one or more of amine crosslinking agents (such as dibasic amines, secondary amines, or tertiary amines), acid anhydride crosslinking agents, and acid crosslinking agents (such as dibasic carboxylic acids or polycarboxylic acids).

[0060] Among them, when the crosslinkable group is a carboxyl group, the crosslinking agent includes one or more of substances having at least two hydroxyl groups in the molecular structure, substances having at least two amino groups, or substances having at least two epoxy groups. For example, the crosslinking agent includes one or more of alcohol crosslinking agents (such as diols, polyols, or resins with hydroxyl groups), amine crosslinking agents, and epoxy crosslinking agents (such as epoxy resins, bifunctional epoxy small molecules).

[0061] Among them, when the crosslinkable group is a hydroxyl group, the crosslinking agent includes one or more of substances having at least two isocyanate groups, at least two carboxyl groups, or at least two ester groups in the molecular structure. That is, the crosslinking agent includes one or more of isocyanate crosslinking agents (such as diisocyanates and polyisocyanates), carboxylic acid crosslinking agents, and ester crosslinking agents (such as dicarboxylic acid esters).

[0062] Among them, when the crosslinkable group is an amino group, the crosslinking agent includes one or more of substances having at least two epoxy groups, at least two carboxyl groups, at least two isocyanate groups, and acid anhydride substances in the molecular structure. That is, the crosslinking agent includes one or more of epoxy crosslinking agents, carboxylic acid crosslinking agents, isocyanate crosslinking agents, and acid anhydride crosslinking agents.

[0063] In some other embodiments of the present application, the crosslinking agent can form non-covalent crosslinking bonds with the polymer with crosslinkable groups. For example, when the crosslinkable group includes a carboxyl group and / or a sulfonic acid group, the crosslinking agent includes a metal salt. In such a case, the metal ions in the metal salt can form non-covalent ionic bonds with the carboxyl group and / or the sulfonic acid group. Among them, the ionic bond can enable the above-mentioned pressure-sensitive adhesive to maintain a stable crosslinked network structure below a certain temperature (such as below 100 °C), improving its thermal stability. When exposed to high temperatures (such as above 180 °C), the ionic bond can dissociate, making the pressure-sensitive adhesive exhibit a certain fluidity, facilitating its re-melting processing and coating, etc. For example, a block-shaped pressure-sensitive adhesive containing an ionic bond in the crosslinked network structure has good thermal stability and does not creep below 100 °C; when the block-shaped pressure-sensitive adhesive is subjected to high-temperature treatment, the ionic bond can be broken, and the pressure-sensitive adhesive can be re-melted and processed into other shapes, such as dots, for easy dot coating, etc. Furthermore, the requirements for coating equipment for this pressure-sensitive adhesive are low, and it can be used for the production of pressure-sensitive adhesive layers on various types of optical cables.

[0064] In the embodiments of the present application, the metal ions in the metal salt include but are not limited to one of zinc ions, magnesium ions, iron ions, cobalt ions, manganese ions, etc. The ionic bonds formed by these metal ions with carboxyl groups, sulfonic acid groups, etc. are relatively strong. The anions in the metal salt can be halogen-free anions. In some embodiments, the metal salt can be an acetylacetonate, sulfate, acetate, benzenesulfonate, etc. of the metal ion. In some examples, the metal salt is a zinc salt, such as zinc acetylacetonate, zinc sulfate, zinc benzenesulfonate, etc.

[0065] In the embodiments of the present application, in the pressure-sensitive adhesive, the total mass ratio of the crosslinking agent can be 0.2%-10%. The addition of an appropriate amount of the crosslinking agent can endow the pressure-sensitive adhesive with good thermal stability through the crosslinked network structure with covalent or non-covalent crosslinking bonds formed between the crosslinking agent and the polymer with crosslinkable groups, and at the same time, it will not reduce the adhesion performance and optical performance of the pressure-sensitive adhesive due to excessive content of the crosslinking agent. Specifically, the mass ratio of the crosslinking agent can be 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.6%, 1.8%, 1.9%, 2%, 2.5%, 3%, 4%, 5%, 8%, etc.

[0066] In the embodiments of the present application, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive is at least 1% or more. To ensure that the above-mentioned pressure-sensitive adhesive has an appropriately high-strength crosslinked network structure at low temperatures (such as below 100°C), and thus can have good thermal stability and mechanical properties. In some embodiments, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive is at least 2% or more.

[0067] In some embodiments of the present application, the main resin further includes a resin without crosslinkable groups. In this case, the main resin in the above-mentioned pressure-sensitive adhesive includes both a polymer with crosslinkable groups and a resin without crosslinkable groups. When introducing a polymer with crosslinkable groups to form a crosslinked network structure of the pressure-sensitive adhesive, introducing a resin without crosslinkable groups can achieve elastic regulation of the pressure-sensitive adhesive, ensure that the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive has good elasticity and is not prone to cracking, and can also achieve regulation of the pressure sensitivity and adhesiveness of the pressure-sensitive adhesive.

[0068] Among them, the resin without crosslinkable groups can be one or more of a styrene block copolymer without crosslinkable groups, an ethylene-vinyl acetate copolymer, a polyurethane, etc. Exemplarily, the styrene block polymer can include a styrene-based diblock copolymer or a styrene-based triblock copolymer, for example, it can be selected from one or more of a styrene-ethylene (SE) copolymer, a styrene-isoprene-styrene (SIS) copolymer, a styrene-ethylene-butene-styrene (SEBS) copolymer, a styrene-butene-styrene (SBS) copolymer, a styrene-ethylene-propylene-styrene (SEPS) copolymer, a styrene-ethylene-propylene (SEP) copolymer, etc.

[0069] In the embodiments of the present application, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive may be 1%-20%, and the mass ratio of the resin without crosslinkable groups in the pressure-sensitive adhesive may be 10%-60%. By regulating the mass ratios of these two main resins in the pressure-sensitive adhesive, comprehensive regulation of the thermal stability, elasticity, adhesiveness, transparency, etc. of the pressure-sensitive adhesive can be achieved. Among them, a polymer with crosslinkable groups in a suitable content can form an appropriate amount of crosslinked network structure with covalent or non-covalent crosslinking bonds through its crosslinkable groups, control the influence of crosslinking bonds on chemical crosslinking, which is beneficial to improving the thermal stability and mechanical properties of the pressure-sensitive adhesive, reducing the precipitation of flame retardants, and at the same time ensuring that the adhesiveness and transparency of the pressure-sensitive adhesive are still relatively high.

[0070] Specifically, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive may be 1%, 2%, 2.2%, 2.5%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15% or 18%, etc. The mass ratio of the resin without crosslinkable groups in the pressure-sensitive adhesive is specifically 15%, 20%, 25%, 30%, 35%, 40%, 42%, 45%, 48%, 50% or 55%, etc. Further, the mass ratio of the resin without crosslinkable groups to the polymer with crosslinkable groups is greater than 1, that is, the former accounts for a larger mass ratio in the pressure-sensitive adhesive than the latter. This can help ensure that the pressure-sensitive adhesive is not overly crosslinked and too hard.

[0071] In some embodiments of the present application, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive is 1%-10%, and the mass ratio of the resin without crosslinkable groups in the pressure-sensitive adhesive may be 20%-50%. When the mass ratios of the two main resins are within the above ranges respectively, it is beneficial for the pressure-sensitive adhesive to have a moderate crosslinked network structure while taking into account good thermal stability and good elasticity, and at the same time making the total mass ratio of the two within a suitable range, so that the above-mentioned phosphate flame retardant can be fully dispersed in the pressure-sensitive adhesive system, which is further beneficial to the dispersion of the nano-inorganic flame retardant, making the pressure-sensitive adhesive have a high transparency appearance, good adhesiveness, high cohesive strength, and excellent flame retardant performance. In some embodiments, the mass ratio of the polymer with crosslinkable groups in the pressure-sensitive adhesive may be in the range of 2%-5%. The mass ratio of the resin without crosslinkable groups in the pressure-sensitive adhesive may be in the range of 25%-40%.

[0072] In the embodiments of the present application, the total mass ratio of the main resin in the pressure-sensitive adhesive is 30%-70%. Among them, when the main resin in the pressure-sensitive adhesive is only a polymer with crosslinkable groups, specifically, the mass ratio of the polymer is 30%-70%; when the main resin in the pressure-sensitive adhesive includes both a polymer with crosslinkable groups and a resin without crosslinkable groups, specifically, the total mass ratio of the polymer with crosslinkable groups and the resin without crosslinkable groups is 30%-70%. Controlling the total mass ratio of the main resin in the pressure-sensitive adhesive within the above range is beneficial to the good dispersion of the above two types of flame retardants in the system, making the pressure-sensitive adhesive have high transparency and good adhesiveness. Specifically, the total mass ratio can be, for example, 32%, 35%, 40%, 42%, 45%, 50%, 55%, 60%, 65%, or 68%, etc. To make the above pressure-sensitive adhesive have both high transparency, good adhesiveness, thermal stability and elasticity, in some embodiments, the total mass ratio of the main resin in the pressure-sensitive adhesive is 30%-60%, and further can be 32%-45%.

[0073] In the present application, the tackifier in the pressure-sensitive adhesive can be used to improve its adhesiveness and, together with the main resin, endow the pressure-sensitive adhesive with good adhesiveness. Among them, the tackifier can be selected from one or more of hydrogenated rosin resin, terpene resin, petroleum resin, etc. In addition, in the pressure-sensitive adhesive, the mass ratio of the tackifier is generally above 10%, and further can be above 20%.

[0074] In some embodiments of the present application, the above pressure-sensitive adhesive may further contain softening oil. Among them, the softening oil can include one or more of naphthenic oil, aromatic oil, paraffin oil, etc. The softening oil can be used to increase the fluidity of the mixed raw materials for preparing the pressure-sensitive adhesive, facilitate the processing of the pressure-sensitive adhesive, and at the same time can also soften the main resin to make the hardness of the pressure-sensitive adhesive not too hard. Of course, in some other embodiments of the present application, the pressure-sensitive adhesive may also not contain softening oil. In the present application, the pressure-sensitive adhesive may contain softening oil with a mass ratio not exceeding 50%, and further contain softening oil with a mass ratio not exceeding 40%.

[0075] In some embodiments of the present application, the above pressure-sensitive adhesive may further contain additives. The additives can be selected from one or more of antioxidants, UV-resistant agents, etc. The additives can be used to reduce the yellowing phenomenon of the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive during use and improve the reliability of long-term use. Of course, in some other embodiments of the present application, the pressure-sensitive adhesive may also not contain additives. In the present application, the pressure-sensitive adhesive may contain additives with a mass ratio not exceeding 3%.

[0076] In the embodiments of the present application, the above-mentioned pressure-sensitive adhesive does not contain halogen elements. For example, each of the flame retardants, cross-linking agents, etc. does not contain halogen elements. When such a pressure-sensitive adhesive is applied to an optical cable, it has basically no corrosive effect on the sheath 10 of the optical cable. And the pressure-sensitive adhesive that does not contain halogen elements and contains the above-mentioned nano-inorganic flame retardant and phosphate flame retardant can still have good flame retardancy and meet the requirements of the optical cable for halogen-free flame retardancy.

[0077] In the embodiments of the present application, by weight, the above-mentioned pressure-sensitive adhesive may include the following raw materials:

[0078] 32 - 70 parts of a main resin; wherein, the main resin at least includes a polymer with a cross-linkable group;

[0079] 0.5 - 3 parts of a cross-linking agent;

[0080] 5 - 15 parts of a nano-inorganic flame retardant;

[0081] 5 - 30 parts of a phosphate flame retardant;

[0082] 20 - 150 parts of a tackifier;

[0083] 0 - 100 parts of a softening oil;

[0084] 0 - 2 parts of an auxiliary agent.

[0085] By reasonably adjusting the raw materials and their ratios for forming the pressure-sensitive adhesive, it is possible to achieve that the pressure-sensitive adhesive has good transparency, flame retardancy, adhesiveness, thermal stability, etc. Among them, when the weight fraction of the softening oil or the auxiliary agent in the pressure-sensitive adhesive is 0, it means that there is no softening oil or auxiliary agent. In some cases, the weight fraction of the phosphate flame retardant in the pressure-sensitive adhesive can be 5 - 15 parts.

[0086] In some embodiments of the present application, by weight, the above-mentioned pressure-sensitive adhesive may include the following raw materials:

[0087] 2 - 10 parts of a polymer with a cross-linkable group;

[0088] 30 - 60 parts of a resin without a cross-linkable group;

[0089] 0.5 - 3 parts of a cross-linking agent;

[0090] 5 - 15 parts of a nano-inorganic flame retardant;

[0091] 5 - 30 parts of a phosphate flame retardant;

[0092] 20 - 150 parts of a tackifier;

[0093] 0 - 100 parts of a softening oil;

[0094] 0 - 2 parts of an auxiliary agent.

[0095] In this application, the above-mentioned pressure-sensitive adhesive can be obtained by melt-mixing various raw materials including a main resin, a cross-linking agent, a nano-inorganic flame retardant, a phosphate flame retardant, and a tackifier, and then cooling to room temperature. Among them, the melt-mixing can be carried out in a high-temperature internal mixer or a twin-screw extruder. The purpose of melting is to melt each raw material to achieve a better mixing effect, especially facilitating the full dispersion of the powdery nano-inorganic flame retardant in the system. In addition, during the melt-mixing, to achieve a better mixing effect, the main resin, nano-inorganic flame retardant, phosphate flame retardant, softening oil, etc. can be mixed first, and then the tackifier, additives, etc. are added, and finally the cross-linking agent is added to promote the formation of a cross-linked network structure. Of course, all the raw materials can also be added to the mixing equipment together.

[0096] Among them, the obtained pressure-sensitive adhesive can be a solid adhesive material, such as a block. When the pressure-sensitive adhesive is applied to an optical cable, the solid adhesive material can be remelted and applied to the outer surface of the optical cable sheath by means of dispensing, etc. After cooling, a pressure-sensitive adhesive layer is formed, such as the adhesive layer 30 mentioned above.

[0097] The above-mentioned pressure-sensitive adhesive provided by the embodiments of this application can take into account good transparency, flame retardancy, thermal stability, adhesiveness, elasticity, etc. It can be applied to an optical cable to form a pressure-sensitive adhesive layer on the sheath of the optical cable for stable adhesion between the optical cable and the wall surface of the optical cable to be laid, to prevent the optical cable from falling off, and to give the optical cable a transparent appearance with good invisibility effect, which can adapt to different home decoration styles. It also makes the optical cable have good flame retardancy and meet the requirements of indoor fire safety. In addition, the pressure-sensitive adhesive provided by the embodiments of this application can also be applied to other fields with high requirements for the transparency and flame retardancy of the adhesive layer, and is not limited to being applied to optical cables.

[0098] As described above in the application, the adhesive layer 30 in the optical cable 100 can be a pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive of the embodiments of this application. The set thickness of the adhesive layer 30 can be set as needed. The thickness of the adhesive layer 30 can be, for example, 50μm - 600μm. A suitable thickness can make the adhesiveness of the adhesive layer 30 more reliable. In some embodiments, the thickness of the adhesive layer 30 can be 80μm, 100μm, 150μm, 200μm, 300μm, 400μm, 500μm, etc.

[0099] As described above in the application, the visible light transmittance of the adhesive layer 30 using the above-mentioned pressure-sensitive adhesive is above 10%, and further can be above 50%, etc. This shows that the transparency of the adhesive layer 30 is high. The softening point of the adhesive layer 30 using the above-mentioned pressure-sensitive adhesive is between 100 - 125°C, and further can be between 110 - 125°C. This shows that the thermal stability of the adhesive layer 30 is good. The peak value of the heat release rate of the adhesive layer 30 using the above-mentioned pressure-sensitive adhesive is less than or equal to 600kW / m2 , and further can be less than or equal to 400 kW / m 2 and so on. This shows that the flame retardant performance of the adhesive layer 30 is good.

[0100] Based on the good flame retardant performance of the adhesive layer 30, the CPR certified fire protection level of the optical cable 100 using it can be above the Eca level. The good fire protection / flame retardant performance of the optical cable 100 is convenient for the indoor application of the optical cable. Among them, the CPR certification is a special certification for building products under the EU CE certification system. The fire protection level of the optical cable CPR certification is evaluated according to the EN13501-6 standard, and Eca is one of the level indicators. The complete fire protection levels of the CPR certified optical cable include Aca, B1ca, B2ca, Cca, Dca, Eca, and Fca in ascending order. In other words, the fire protection level of the optical cable 100 in the embodiment of the present application can reach the Eca level or the Fca level.

[0101] Please continue to refer to Figure 1A and Figure 1B , in some embodiments, to facilitate tearing the sheath 10, a groove 101 can be provided on the sheath 10. The groove 101 can be provided in the first radial direction of the optical fiber 20 (i.e., the z-axis direction in the figure), and the groove 101 is opened from one end of the sheath 10 to the other end along the extending direction (the extending direction of the groove 101 is parallel to the length direction of the sheath 10, the y-axis direction in the figure). In other words, the extending length of the groove 101 is consistent with the extending length of the sheath 10. It is convenient to tear the sheath 10 from this groove, quickly expose the end of the optical fiber 20, further improve the installation efficiency of the optical cable, etc., or improve the maintenance efficiency of the optical cable after the optical fiber 20 is damaged.

[0102] Among them, the cross-sectional shape of the groove 101 along the radial direction of the optical fiber 20 can be any shape such as an inverted trapezoid, a rectangle, a square, and a triangle. Figure 1A In [reference], the cross-sectional shape of the groove 101 along the radial direction of the optical fiber 20 is specifically a triangle, where the apex angle of the triangle is located at the bottom of the groove 101 (the groove wall opposite to the opening of the groove). In this way, it is easier to tear the sheath 10 from the bottom of the groove 101. In addition, the number of the grooves 101 provided on the sheath 10 can be one or two. Figure 1A In [reference], the two grooves 101 are respectively provided on the opposite sides of the sheath 10 along the z-axis direction. That is, the two grooves 101 are provided on the upper surface and the lower surface of the sheath 10. Among them, the adhesive layer 30 can cover or not cover the groove 101 on the surface of the sheath 10 where it is located. When the adhesive layer 30 does not cover the groove 101 (as shown below Figure 2 ), it is more convenient to tear the sheath 10 from this groove later and retain the end of the optical fiber 20.

[0103] In some embodiments of the present application, refer toFigure 1C In addition, the optical cable 100 further includes a release film 40; the release film 40 is disposed on the surface of the adhesive layer 30, specifically on the surface of the adhesive layer 30 facing away from the sheath 10. The release film 40 has removability and is disposed on the surface of the adhesive layer 30 before the optical cable 100 is installed, protecting the adhesive layer 30, preventing the optical cable from sticking during transportation and storage, and avoiding contamination of the bonding surface of the adhesive layer 30 by the external environment. When specifically installing the optical cable 100 of the embodiment of the present application, the release film 40 on the surface of the adhesive layer 30 can be torn off first, and then the optical cable 100 can be stably bonded to the wall surface through the adhesive layer 30, improving the laying efficiency of the optical cable of the embodiment of the present application and also improving the laying reliability of the optical cable of the embodiment of the present application.

[0104] In some other embodiments of the present application, referring to Figure 2 the optical cable 100 further includes two wires 50. Both the optical fiber 20 and the wires 50 are located inside the sheath 10, and the extending directions of the optical fiber 20 and the wires 50 are the same. In this case, Figure 2 the optical cable shown can be called an "optical and electrical composite cable". The wire 50 functions as a conductor and is generally disposed on the outer periphery of the optical fiber 20 without contacting the optical fiber 20. Figure 2 In, the optical fiber 20 is disposed at the central position of the sheath 10, and the two wires 50 are symmetrically disposed on the outer periphery of the optical fiber 20 respectively. The wire 50 is generally a copper wire.

[0105] The foregoing Figures 1A to 1C and Figure 2 In, the optical fiber 20 is specifically a single-core optical fiber as an example, but it can be understood that the optical cable can also have multi-core optical fibers. As Figure 3 shown, the optical cable 100 can have multiple optical fibers 20 to achieve multi-core communication. There is a certain interval between the optical fibers 20, but they are all wrapped by the common sheath 10.

[0106] Generally speaking, the use of the above-mentioned pressure-sensitive adhesive in the adhesive layer 30 of the optical cable 100 provided by the embodiment of the present application enables the optical cable to have good invisibility, flame retardancy and laying reliability, thereby facilitating the wide application of the FTTR solution.

[0107] The following further describes the embodiments of the present application through multiple embodiments.

[0108] Embodiment 1

[0109] A pressure-sensitive adhesive includes the following raw materials in parts by weight:

[0110] Maleic anhydride-modified styrene block polymer: 5 parts;

[0111] Styrene block polymer without crosslinkable groups: 60 parts;

[0112] Nano-inorganic flame retardant (specifically aluminum hypophosphite with an average particle size of 80 nm): 15 parts;

[0113] Phosphate ester flame retardant (specifically resorcinol bis(diphenyl phosphate)): 15 parts;

[0114] Tackifier (specifically hydrogenated rosin resin): 20 parts;

[0115] Naphthenic oil: 50 parts;

[0116] Crosslinking agent (specifically zinc acetylacetonate): 3 parts;

[0117] Auxiliary agent (antioxidant + UV absorber): 2 parts.

[0118] Among them, the above-mentioned pressure-sensitive adhesive can be prepared by the following method: First, maleic anhydride-modified styrene block polymer, styrene block polymer without crosslinkable groups, nano-inorganic flame retardant, phosphate ester flame retardant, and naphthenic oil are added to a high-temperature internal mixer to melt and mix evenly. Then, a tackifier and an auxiliary agent are added for melt mixing, and then a crosslinking agent is added for melt mixing. Finally, it is cooled to room temperature to obtain a solid pressure-sensitive adhesive.

[0119] Example 2

[0120] A pressure-sensitive adhesive is obtained by melt mixing the following raw materials in the following weight parts:

[0121] Maleic anhydride-modified styrene block polymer: 5 parts;

[0122] Styrene block polymer without crosslinkable groups: 40 parts;

[0123] Polyurethane without crosslinkable groups: 20 parts;

[0124] Ethylene-vinyl acetate copolymer without crosslinkable groups: 20 parts;

[0125] Nano-inorganic flame retardant (specifically aluminum phosphate with a particle size of 500 nm): 15 parts;

[0126] Cyclic phosphate ester flame retardant: 15 parts;

[0127] Tackifier (specifically hydrogenated rosin resin): 20 parts;

[0128] Naphthenic oil: 50 parts;

[0129] Crosslinking agent (specifically zinc acetylacetonate): 3 parts;

[0130] Auxiliary agent (antioxidant + UV absorber): 2 parts.

[0131] The preparation method of the pressure-sensitive adhesive in Example 2 is basically the same as that in Example 1.

[0132] Example 3

[0133] A pressure-sensitive adhesive, the main difference in its preparation from that of Example 1 is that a resin without crosslinkable groups is not used.

[0134] Specifically, the pressure-sensitive adhesive of Example 3 is obtained by melt mixing the following raw materials in parts by weight:

[0135] Maleic anhydride modified styrene block polymer: 60 parts;

[0136] Nanoscale inorganic flame retardant (same as Example 1): 15 parts;

[0137] Phosphate ester flame retardant (same as Example 1): 15 parts;

[0138] Tackifier (specifically hydrogenated rosin resin): 40 parts;

[0139] Naphthenic oil: 50 parts;

[0140] Crosslinking agent (specifically zinc acetylacetonate): 3 parts;

[0141] Auxiliary agent (antioxidant + UV absorber): 2 parts.

[0142] Example 4

[0143] A pressure-sensitive adhesive, the main difference from Example 1 is that the total weight of the nanoscale inorganic flame retardant and the phosphate ester flame retardant is still 30 parts, but the nanoscale inorganic flame retardant is 10 parts and the phosphate ester flame retardant is 20 parts.

[0144] Example 5

[0145] A pressure-sensitive adhesive, the main difference from Example 1 is that the total weight of the nanoscale inorganic flame retardant and the phosphate ester flame retardant is still 30 parts, but the nanoscale inorganic flame retardant is 20 parts and the phosphate ester flame retardant is 10 parts.

[0146] Example 6

[0147] A pressure-sensitive adhesive is obtained by melt mixing the following raw materials in parts by weight:

[0148] Maleic anhydride modified styrene block polymer: 5 parts;

[0149] Styrene block polymer without crosslinkable groups: 55 parts;

[0150] Nanoscale inorganic flame retardant: 15 parts;

[0151] Phosphate ester flame retardant: 30 parts;

[0152] Hydrogenated rosin resin: 20 parts;

[0153] Naphthenic oil: 40 parts;

[0154] Crosslinking agent: 3 parts;

[0155] Auxiliary agent: 2 parts.

[0156] Example 7

[0157] A pressure-sensitive adhesive obtained by melt-mixing the following raw materials in mass percentage:

[0158] Maleic anhydride-modified styrene block polymer: 2.9%;

[0159] Styrene block polymer without crosslinkable groups: 42.9%;

[0160] Nanometer inorganic flame retardant: 5%;

[0161] Phosphate ester flame retardant: 5%;

[0162] Hydrogenated rosin resin: 11.8%;

[0163] Naphthenic oil: 29.4%;

[0164] Crosslinking agent: 1.8%;

[0165] Auxiliary agent: 1.2%.

[0166] To highlight the beneficial effects of the embodiments of the present application, the following comparative examples are set.

[0167] Comparative Example 1

[0168] A pressure-sensitive adhesive, which is different from Example 1 in that: the flame retardant in the preparation raw materials of the pressure-sensitive adhesive is only 30 parts by weight of nanometer inorganic flame retardant and does not contain phosphate ester flame retardant.

[0169] Comparative Example 2

[0170] A pressure-sensitive adhesive, which is different from Example 1 in that: the flame retardant in the preparation raw materials of the pressure-sensitive adhesive is only 30 parts by weight of phosphate ester flame retardant and does not contain nanometer inorganic flame retardant.

[0171] Comparative Example 3

[0172] A pressure-sensitive adhesive obtained by melt-mixing the following raw materials in parts by weight:

[0173] Styrene block polymer without crosslinkable groups: 68 parts;

[0174] Nanometer inorganic flame retardant: 15 parts;

[0175] Phosphate ester flame retardant: 15 parts;

[0176] Hydrogenated rosin resin: 20 parts;

[0177] Naphthenic oil: 50 parts;

[0178] Auxiliary agent: 2 parts.

[0179] To strongly support the beneficial effects brought by the technical solutions of the embodiments of the present application, the pressure-sensitive adhesives provided in the above-mentioned embodiments and comparative examples are subjected to the following performance tests shown in Table 1 below, and the results are also summarized in Table 1 below.

[0180] Table 1 Performance test results of pressure-sensitive adhesives

[0181]

[0182] It can be learned from Table 1 that, compared with Comparative Examples 1-2 in which the pressure-sensitive adhesive only contains an inorganic flame retardant or an organophosphate flame retardant, the pressure-sensitive adhesive of the embodiment of the present application simultaneously introduces a nano-inorganic flame retardant and an organophosphate flame retardant, and with the help of the cross-linked network structure formed by the cross-linkable polymer and the cross-linking agent in the main resin to inhibit the precipitation of these two flame retardants, the pressure-sensitive adhesive of the embodiment of the present application can better balance transparency and flame retardancy, and at the same time has good adhesiveness and thermal stability. In addition, from the comparison between Examples 1, 4 and Example 5, it can be learned that when the mass ratio of the nano-inorganic flame retardant to the phosphate flame retardant in the pressure-sensitive adhesive is in the range of 0.5 to less than 2, the visible light transmittance and adhesiveness of the pressure-sensitive adhesive are better.

[0183] Furthermore, using the pressure-sensitive adhesives of the embodiments of the present application to form a pressure-sensitive adhesive layer on the outer surface of the sheath of the optical cable, the optical cable can have a good stealth effect and a high fire protection level (the fire protection level certified by CPR can be above the Eca level), and has good adhesiveness on the wall surface such as latex paint, and the market competitiveness of the optical cable is outstanding.

[0184] It should be noted that the terms "arranged", "connected", "installed", etc. in the present application should be understood in a broad sense. For example, it can be directly arranged, connected, or installed, or can be indirectly arranged, connected, or installed through an intermediate medium. The directional terms mentioned in the present application, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "front", "back", "bottom", "top", "side", etc., are only for better and clearer illustration and understanding of the present application, rather than indicating or implying that the components referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0185] It should be understood that the numerical numbers such as "first", "second", etc. used in this application are only for the convenience of description and do not limit the scope of this application. In the description of this application, unless otherwise specified, the meaning of "multiple (kinds)" refers to greater than or equal to two (kinds). "At least one (kind)" means one (kind) or more than one (kind). "At least one (item) of the following" or its similar expression refers to any combination of these items, including any combination of single item (s) or plural items (s). For example, "at least one (item) of a, b, or c", or "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0186] In addition, the numerical range represented by "-" in this application refers to the range including the numerical values recorded before and after "-" as the minimum value and the maximum value respectively. In this application, for the expression of the parameter range, such as "greater than or equal to (≥)", "less than or equal to (≤)", "above...", "below...", the corresponding number is included. The numerical values and numerical ranges involved in the embodiments of this application are approximate values. Affected by manufacturing processes / testing methods, etc., there may be a certain range of errors, and those skilled in the art can consider this part of the errors to be negligible.

Claims

1. A pressure-sensitive adhesive for an optical cable, which is used to be disposed on the outer surface of the sheath of the optical cable. Characterized in that, the pressure-sensitive adhesive comprises a main resin, a crosslinking agent, a nano-inorganic flame retardant, a phosphate ester flame retardant and a tackifier. Among them, the main resin at least contains a polymer with crosslinkable groups, and the polymer and the crosslinking agent are used to make the pressure-sensitive adhesive form a crosslinked network structure; the visible light transmittance of the pressure-sensitive adhesive is above 10%.

2. The pressure-sensitive adhesive according to claim 1, Characterized in that, The peak value of the thermal release rate of the pressure-sensitive adhesive is less than or equal to 600 kW / m 2 .

3. The pressure-sensitive adhesive according to claim 1 or 2, Characterized in that, The visible light transmittance of the pressure-sensitive adhesive is above 50%, and the peak value of the heat release rate is less than or equal to 400 kW / m 2 .

4. The pressure-sensitive adhesive according to any one of claims 1-3, Characterized in that, the softening point of the pressure-sensitive adhesive is between 100-125 °C.

5. The pressure-sensitive adhesive according to any one of claims 1-4, Characterized in that, the peeling force of the adhesive layer formed by the pressure-sensitive adhesive on the polyethylene terephthalate film is greater than or equal to 0.4 N / m.

6. The pressure-sensitive adhesive according to any one of claims 1-5, Characterized in that, the total mass ratio of the nano-inorganic flame retardant and the phosphate ester flame retardant in the pressure-sensitive adhesive is 5-40%.

7. The pressure-sensitive adhesive according to claim 6, Characterized in that, the mass ratio of the nano-inorganic flame retardant to the phosphate ester flame retardant is (0.2-1.2):

1.

8. The pressure-sensitive adhesive according to claim 6 or 7, Characterized in that, the mass ratio of the nano-inorganic flame retardant in the pressure-sensitive adhesive is 5-20%.

9. The pressure-sensitive adhesive according to any one of claims 1-8, Characterized in that, the size of the nano-inorganic flame retardant is between 1 nm and 500 nm.

10. The pressure-sensitive adhesive according to any one of claims 1-9, Characterized in that, the nano-inorganic flame retardant includes one or more of aluminum phosphate, zinc phosphate, aluminum hypophosphite, zinc oxide; the phosphate ester flame retardant includes one or more of cetyl phosphate, octadecyl phosphate, tetraphenylbisphenol A diphosphate, bisphenol A bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), cyclic phosphate, triethyl phosphate.

11. The pressure-sensitive adhesive according to any one of claims 1-10, Characterized in that, the crosslinkable groups include one or more of epoxy group, carboxyl group, sulfonic acid group, hydroxyl group, amino group.

12. The pressure-sensitive adhesive according to any one of claims 1-11, Characterized in that, the crosslinkable groups include carboxyl group and / or sulfonic acid group, and the crosslinking agent includes a metal salt; wherein, the metal ions in the metal salt can form non-covalent ionic bonds with the carboxyl group and / or the sulfonic acid group.

13. The pressure-sensitive adhesive according to claim 12, Characterized in that, the metal ions in the metal salt include one of zinc ions, magnesium ions, iron ions, cobalt ions, manganese ions.

14. The pressure-sensitive adhesive according to any one of claims 1-13, Characterized in that, the total mass ratio of the crosslinking agent in the pressure-sensitive adhesive is 0.2%-10%.

15. The pressure-sensitive adhesive according to any one of claims 1-14, Characterized in that, the main resin further includes a resin without crosslinkable groups.

16. The pressure-sensitive adhesive according to claim 15, wherein the mass proportion of the polymer with crosslinkable groups in the pressure-sensitive adhesive is 1%-20%, and the mass proportion of the resin without crosslinkable groups in the pressure-sensitive adhesive is 10%-60%.

17. The pressure-sensitive adhesive according to any one of claims 1-16, wherein the total mass proportion of the main resin in the pressure-sensitive adhesive is 30%-70%.

18. The pressure-sensitive adhesive according to any one of claims 1-17, wherein by weight, the pressure-sensitive adhesive comprises the following raw materials: 32-70 parts of main resin; 0.5-3 parts of crosslinking agent; 5-15 parts of nano-inorganic flame retardant; 5-30 parts of phosphate flame retardant; 20-150 parts of tackifier; 0-100 parts of softening oil; 0-2 parts of auxiliary agent.

19. An optical cable, wherein the optical cable comprises a sheath, an optical fiber, and an adhesive layer. Among them, the optical fiber is located inside the sheath, and the adhesive layer is provided on at least part of the outer surface of the sheath. The adhesive layer uses the pressure-sensitive adhesive according to any one of claims 1-18.

20. The optical cable according to claim 19, wherein the thickness of the adhesive layer is 50-600 μm.

21. The optical cable according to any one of claims 19-20, wherein the fire protection grade of the optical cable is above Eca grade.

22. The optical cable according to any one of claims 19-21, wherein the optical cable further comprises a release film; the release film is provided on the surface of the adhesive layer.

23. The optical cable according to any one of claims 19-22, wherein the optical fiber is a single-core optical fiber or a multi-core optical fiber.

24. The optical cable according to any one of claims 19-23, wherein the optical cable further comprises a wire, and the wire is located inside the sheath.

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