Flame-retardant cotton paper adhesive tape

Abstract

The invention provides a flame-retardant cotton paper adhesive tape which is sequentially provided with a release layer, a first flame-retardant adhesive layer, a base material layer, a second flame-retardant adhesive layer and a release layer, and the flame-retardant adhesive layer is formed by mixing an acrylate polymer, a flame retardant, modified rosin resin, a curing agent and hollow glass microspheres. Wherein the acrylate polymer comprises an acrylate monomer, a phosphorus-containing monomer and a nitrogen-containing monomer, the modified rosin resin is phosphate-group-containing modified rosin resin, the flame retardant is a phosphorus-nitrogen compound flame retardant, and the flame retardance of the adhesive tape is improved by using the phosphorus-containing and nitrogen-containing monomer or the flame retardant, the modified rosin resin and the hollow glass microspheres. The adhesive is simple in structural design and use, good in flame retardant property and adhesion effect and suitable for being applied to automobile batteries or battery cells.

Description

Technical Field

[0001] This invention relates to the field of adhesive tapes, and in particular to a flame-retardant cotton paper tape. Background Technology

[0002] With the rapid development of new energy vehicles and mobile phones, the demand for lithium batteries has surged, leading to a corresponding increase in the use of adhesive tapes for battery packaging and cell insulation bonding. However, batteries inevitably generate heat during operation. Excessive temperatures can not only cause ordinary adhesive tapes to lose adhesion or even detach, but also pose a fire hazard. Currently available flame-retardant tapes generally face challenges in meeting high-temperature bonding stability requirements, especially after the addition of flame retardants, which often results in significant degradation of key properties such as adhesion, making it difficult to firmly adhere to the battery casing.

[0003] To address the aforementioned technical problems, existing technologies offer several solutions. Invention patent CN119529686A discloses an insulating flame-retardant tape. This modified flame retardant, prepared by adding flame-retardant additives and compounding with magnesium hydroxide, zinc borate, and melamine, generates an expanded char layer during combustion to block heat and oxygen, achieving a flame-retardant effect and improving the tape's high-temperature resistance. However, since the main flame retardant is magnesium hydroxide, a high dosage is required to achieve effective flame retardancy, and it disrupts the continuity of the molecular chains, causing the tape to become brittle and unsuitable for bonding to uneven surfaces such as car batteries. Another invention patent, CN117624484A, discloses a highly flame-retardant double-sided tape. This tape uses a highly flame-retardant acrylic resin instead of commonly used tackifying resin, resulting in advantages such as high bonding strength, good flame retardancy, excellent temperature resistance, and strong cohesion. However, its peel strength is only around 20 N / in (approximately 7.87 N / 25 mm). For power battery fixing applications that need to withstand continuous vibration and bumpy conditions during vehicle operation, this level of adhesive strength is still insufficient, and there is a potential risk that the tape may detach from the battery surface under dynamic stress.

[0004] Therefore, the market urgently needs to develop a flame-retardant tape with a relatively simple manufacturing process and structure that can provide sufficiently high and stable adhesion while maintaining excellent flame-retardant properties, specifically suitable for automotive battery or cell applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention utilizes phosphorus- and nitrogen-containing monomers or flame retardants, modified rosin resin, and hollow glass microspheres to enhance the flame retardancy of the tape, providing a promising technical approach for flame-retardant tapes.

[0006] This invention provides a flame-retardant cotton paper tape, characterized in that it comprises, in sequence, a release layer, a first flame-retardant adhesive layer, a substrate layer, a second flame-retardant adhesive layer, and a release layer, wherein...

[0007] The first and second flame-retardant adhesive layers have a thickness of ≥60μm and are composed of a mixture of acrylate polymer, flame retardant, modified rosin resin, hollow glass microspheres, and curing agent.

[0008] The acrylate polymer comprises acrylate monomers, phosphorus-containing monomers, and nitrogen-containing monomers;

[0009] The modified rosin resin is obtained by esterification of rosin resin and pentaerythritol phosphate to obtain a modified rosin resin containing phosphate ester groups.

[0010] The flame retardant is a phosphorus-nitrogen compound flame retardant.

[0011] The hollow microspheres are an inorganic non-metallic material with a shell-core structure.

[0012] Furthermore, the acrylate monomer is one or more of butyl acrylate, methyl methacrylate, and isooctyl acrylate.

[0013] Furthermore, the phosphorus-containing monomer is ethylene glycol methacrylate and / or vinylphosphonic acid.

[0014] Furthermore, the nitrogen-containing monomer is dimethylaminoethyl methacrylate and / or acrylamide.

[0015] Furthermore, the hollow glass microspheres are a spherical material composed of one or more of silicon dioxide, boron oxide, and aluminum oxide, with a pore size of 10-200 μm.

[0016] On the one hand, phosphorus-containing groups decompose upon heating to generate phosphoric acid and polyphosphoric acid, which catalyze the dehydration and carbonization of the butyl acrylate segment, converting flammable hydrocarbon chains into an aromatic char layer and reducing the generation of combustible gases such as propylene and butene during combustion. Furthermore, phosphorus promotes the formation of phosphorus-oxygen-carbon bonds in the char layer, improving its high-temperature resistance and density. In addition, amino groups decompose upon heating into non-combustible gases such as NH3, N2, and water vapor, further diluting the oxygen and combustible gas concentrations in the combustion zone, thereby inhibiting combustion.

[0017] On the other hand, the rosin resin molecules commonly used in acrylic tape products contain conjugated double bonds and carboxyl groups, which will burn when exposed to an open flame at room temperature. Under the action of toluenesulfonic acid, a strong acid catalyst, the hydroxyl groups in the pentaerythritol phosphate ester molecule can undergo an esterification reaction with the carboxyl groups in the rosin resin, simultaneously incorporating the phosphate ester groups into the rosin molecular chain. Furthermore, the introduction of phosphorus promotes the formation of phosphorus-oxygen bonds between molecular chains, increasing the activation energy of the resin's thermal degradation, thereby raising the ignition point. Additionally, the modified rosin resin has a larger molecular weight and stronger molecular chain rigidity, resulting in a higher thermal decomposition temperature.

[0018] Furthermore, the hollow glass microspheres themselves have low thermal conductivity, while the air inside has even lower thermal conductivity. This composite structure of "glass shell + gas core" not only reduces the overall thermal conductivity of the material, decreasing heat transfer to the interior, but also dilutes the concentration of combustibles. Additionally, the hollow glass microspheres expand when heated, acting as a physical support embedded in the dehydrated char layer, reducing cracking or detachment of the char layer and thus enhancing its heat insulation and oxygen barrier capabilities, further delaying the combustion of the substrate layer. Ultimately, this results in a synergistic flame retardant effect through heat insulation, oxygen barrier, and dilution.

[0019] Furthermore, the release layer is a release film or release paper, with a release force of ≤20g / inch and a thickness of 110-120μm.

[0020] Furthermore, the substrate layer is a cotton paper substrate with a thickness of 35 μm.

[0021] Furthermore, the cotton paper substrate is a loose and porous cotton paper made from wood pulp.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The structure is simple to design and use. The five-layer composite structure of this invention can simultaneously achieve flame retardancy, adhesion and substrate support in a single bonding action. The simple operation mode of directly applying adhesive after removing the release layer significantly simplifies the packaging process.

[0024] 2. Excellent flame retardant properties: Commonly used rosin resins on the market will promote combustion with open flames. This invention, through modification experiments, can raise the ignition point to over 500℃, enhancing the flame retardancy of the entire system. At the same time, the use of phosphorus and nitrogen-containing monomers to synthesize acrylic polymers and covalently bond flame retardant elements to the resin skeleton also increases the flame retardant properties from the raw materials.

[0025] 3. Excellent adhesion. On one hand, this application uses cotton paper as the substrate, which is soft and flexible, allowing it to adhere tightly to irregular and uneven battery surfaces without gaps. On the other hand, common acrylic polymers contain a large amount of flame retardants, which significantly reduces the temperature resistance of the tape while increasing flame retardancy. This application achieves flame retardancy by selecting phosphorus and nitrogen-containing monomers and modifying rosin resin, rather than simply increasing the amount of flame retardant, ensuring that the peel strength of this product still reaches over 30N / 25mm. Detailed Implementation

[0026] Table 1 - Raw Material Information

[0027]

[0028] Example 1

[0029] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0030] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0031] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0032] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0033] Example 2

[0034] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0035] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0036] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 30 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0037] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0038] Example 3

[0039] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 30 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0040] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0041] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0042] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0043] Example 4

[0044] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 10 parts of phosphorus-containing monomer ethylene glycol methacrylate, 20 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65°C, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65°C for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0045] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0046] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0047] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0048] Example 5

[0049] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0050] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0051] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 3 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0052] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0053] Comparative Example 1

[0054] S1. Synthesis of acrylate polymer: 70 parts of butyl acrylate monomer, 30 parts of isooctyl acrylate, and 50 parts of ethyl acetate were added to a 2L glass reactor and stirred thoroughly. Nitrogen gas was continuously introduced at a flow rate of 0.5L / min, and the temperature was gradually increased to 65℃. Then, 0.3 parts of azobisisovalerate initiator were added, and the reaction was continued at 65℃ for 8 hours. Finally, 20 parts of ethyl acetate were added for dilution to obtain the desired acrylate polymer.

[0055] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0056] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0057] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0058] Comparative Example 2

[0059] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0060] S2. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts rosin resin, 20 parts phosphorus and nitrogen compound flame retardant, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0061] S3. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0062] Comparative Example 3

[0063] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0064] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0065] S3. Preparation of flame retardant adhesive: Weigh 100 parts acrylic polymer, 10 parts modified rosin resin, 10 parts ethyl acetate, 1.5 parts hollow glass microspheres, and 0.5 parts curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0066] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0067] Comparative Example 4

[0068] S1. Synthesis of acrylate polymer: In a 2L glass reactor, add 20 parts of phosphorus-containing monomer ethylene glycol methacrylate, 10 parts of nitrogen-containing monomer dimethylaminoethyl methacrylate, 70 parts of acrylate monomer butyl acrylate, and 50 parts of ethyl acetate, and stir until thoroughly mixed. Continuously purge with nitrogen gas at a flow rate of 0.5 L / min, gradually raise the temperature to 65℃, then add 0.3 parts of initiator azobisisovalerate. Continue the reaction at 65℃ for 8 hours, then add 20 parts of ethyl acetate for dilution to obtain the desired acrylate polymer.

[0069] S2. Modification of rosin resin: First, mix 50 parts of rosin resin with 50 parts of ethyl acetate to form a uniform solution. Then, gradually add 15 parts of pentaerythritol phosphate to the solution. After reacting at 80°C for 4 hours, add 0.5 parts of toluenesulfonic acid and heat to 105°C to continue the reaction for 2 hours to obtain modified rosin resin.

[0070] S3. Preparation of flame retardant adhesive: Weigh 100 parts of acrylic polymer, 10 parts of modified rosin resin, 20 parts of phosphorus-nitrogen compound flame retardant, 10 parts of ethyl acetate, and 0.5 parts of curing agent isophorone diisocyanate. Mix and stir for 20 minutes to obtain flame retardant adhesive.

[0071] S4. Preparation process of flame-retardant cotton paper tape: A 65μm thick layer of flame-retardant adhesive is evenly coated onto a 120μm thick release paper using a coater. The coated paper is then placed in an oven at 80℃ for 2 minutes to dry and cure, followed by another 3 minutes at 110℃. After removing from the oven, the release paper with the flame-retardant adhesive is laminated onto a 35μm thick cotton paper substrate using a laminating machine, completing the coating on one side. The other side is then coated, dried, cured, and laminated in the same way to produce the flame-retardant cotton paper tape.

[0072] Performance testing

[0073] The flame-retardant cotton paper tapes prepared in Examples 1-5 and Comparative Examples 1-4 were subjected to performance tests according to the following test methods. The test results are shown in Table 3.

[0074] (1) 180° peel force test: Cut the sample into strips 25mm wide and 20mm long for later use. The test method is carried out according to the method A of ASTM international standard D3330. Tear off the release film on one side of the tape, cover it with 25μm PET backing material, press it firmly, and measure the peel force of the other side of the tape on the SUS board. After bonding, place it under the test temperature and humidity conditions for 20 minutes before testing. The average adhesive force required to tear the strip from the panel is expressed as N / 25mm.

[0075] (2) Static shear holding force test at 23℃: The static shear holding force test was conducted according to the procedure A of ASTM international standard D3654. The test area was 25*25mm, the load was 500g, the test room temperature was 23℃, the test board was SUS board, and the drop time was recorded in min.

[0076] (3) Vertical flame retardancy test: Cut the sample into strips 50mm wide and 130mm long. For the flame retardancy test method, refer to GB / T2408-2008 Test Methods for Flammability of Plastics (Horizontal and Vertical Methods) and UL_94-2006 Test forflammability of plastic materials for parts in devices and appliances, page 15, 8.1 Test Criteria. Test procedure: Place the Bunsen burner (flame height 20±1mm) at the center below the sample, with the nozzle of the Bunsen burner 10±1mm from the bottom of the sample. Ignition time is 10±0.5s. After 10±0.5s of ignition, move the Bunsen burner away at least 150mm at a speed of 300mm / sec. Simultaneously, start recording the afterflame time t1. When the afterflame stops, immediately ignite for 10±0.5s. After 10±0.5s of ignition, move the Bunsen burner away at least 150mm at a speed of 300mm / sec. Simultaneously, record the afterflame time t2 and the afterburn time t3. The flame retardancy evaluation criteria can be found in Table 2.

[0077] Table 2 - Vertical Flame Retardancy Evaluation Criteria

[0078]

[0079] Table 3 - Formulations and test results of Examples 1-5 and Comparative Examples 1-4

[0080]

[0081] Comparative Example 1 showed that the addition of phosphorus- and nitrogen-containing monomers significantly improved flame retardant performance compared to conventional monomers. Comparative Example 2 showed that modification of rosin resin resulted in a good improvement in flame retardant performance. Comparative Example 3 showed that the addition of flame retardants significantly improved the flame retardant performance of the tape, but also significantly reduced its peel strength and holding power. Combined with Example 2, it was found that while meeting flame retardant performance requirements, the amount of flame retardant should not be excessive; a suitable dosage needs to be found. Comparative Example 4 showed that the addition of hollow glass microspheres slightly improved the flame retardant performance of the tape, but also slightly reduced its peel strength and holding power. Combined with Example 5, it was found that excessive amounts of hollow glass microspheres significantly reduced the peel strength and holding power of the tape; therefore, an appropriate dosage of hollow glass microspheres is necessary.

[0082] A comparison of Examples 1 and 3 shows that excessive phosphorus-containing monomer content leads to a decrease in the peel strength and holding power of the tape. This may be because excessive phosphorus content reduces the compatibility of the polymer, affecting the actual performance. A comparison of Examples 1 and 4 shows that excessive nitrogen-containing monomer content is detrimental to improving flame retardant performance. This may be because excessive nitrogen content causes the gas generation rate to be too fast, leading to the rupture of the char layer formed during combustion, which is detrimental to flame retardancy.

[0083] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure made using the content of the present invention specification, or any direct or indirect application in other related technical fields, shall also be included within the patent protection scope of the present invention.

Claims

1. A flame-retardant cotton paper tape, characterized in that, It includes, in sequence, a release layer, a first flame-retardant adhesive layer, a substrate layer, a second flame-retardant adhesive layer, and a release layer, wherein, The first and second flame-retardant adhesive layers have a thickness of ≥60μm and are composed of acrylate polymer, flame retardant, modified rosin resin, curing agent, and hollow glass microspheres. The acrylate polymer comprises acrylate monomers, phosphorus-containing monomers, and nitrogen-containing monomers; The modified rosin resin is obtained by esterification of rosin resin and pentaerythritol phosphate to obtain a modified rosin resin containing phosphate ester groups. The flame retardant is a phosphorus-nitrogen compound flame retardant; The hollow glass microspheres are an inorganic non-metallic material with a shell-core structure.

2. The flame-retardant cotton paper tape according to claim 1, characterized in that, The acrylate monomer is one or more of butyl acrylate, methyl methacrylate and isooctyl acrylate.

3. The flame-retardant cotton paper tape according to claim 1, characterized in that, The phosphorus-containing monomer is ethylene glycol methacrylate and / or vinylphosphonic acid, and the nitrogen-containing monomer is dimethylaminoethyl methacrylate and / or acrylamide.

4. The flame-retardant cotton paper tape according to claim 1, characterized in that, The hollow glass microspheres are a spherical material composed of one or more of silicon dioxide, boron oxide, and aluminum oxide, with a pore size of 10-200 μm.

5. A flame-retardant cotton paper tape according to any one of claims 1-4, characterized in that, The release layer is a release film or release paper with a release force of ≤20g / inch and a thickness of 110-120μm.

6. A flame-retardant cotton paper tape according to any one of claims 1-4, characterized in that, The substrate layer is a cotton paper substrate with a thickness of 35μm.

7. The flame-retardant cotton paper tape according to claim 6, characterized in that, The cotton paper substrate is a loose and porous cotton paper made from wood pulp.

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