Flame-retardant high-temperature-resistant impact-resistant pressure-sensitive adhesive, preparation method and application thereof

Abstract

This invention relates to the field of pressure-sensitive adhesive technology, specifically to a flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive, its preparation method, and its application. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive, by weight, comprises 80-95 parts of polyacrylate containing organophosphorus and polysiloxane side chains, 5-20 parts of tackifying resin, 80-150 parts of solvent, and 0.1-1 parts of curing agent. The polyacrylate containing organophosphorus and polysiloxane side chains is obtained by reacting a single-ended epoxy polysiloxane, an organophosphorus compound containing epoxy groups, and a carboxyl-containing polyacrylate. Without the use of external flame retardants, the flame retardancy of the acrylic pressure-sensitive adhesive is enhanced through chemical bonding of the organophosphorus compound and the polysiloxane, while simultaneously improving the adhesion and impact resistance at high temperatures.

Description

Technical Field

[0001] This invention relates to the field of pressure-sensitive adhesive technology, specifically to a flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive, its preparation method, and its application. Background Technology

[0002] Because the polymer, the main component of pressure-sensitive adhesives, is flammable, flame retardants are often added to reduce fire risk in high-temperature and flammable environments such as trains, automobiles, aircraft, and electronic and electrical appliances. Currently, commonly used flame retardants on the market include inorganic flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, halogen-based flame retardants, and silicone-based flame retardants. Among these, halogen-based flame retardants are banned by many countries / organizations because they produce toxic and corrosive hydrohalic acids during the flame-retardant process, posing a threat to human health. Nitrogen-based flame retardants have poor flame-retardant effects when used alone and must be used in conjunction with phosphorus-based flame retardants. Phosphorus-based flame retardants mainly achieve their flame-retardant effect by forming an isolating film, while silicone-based flame retardants achieve their effect mainly by generating a cracked carbon layer and improving the oxidation resistance of the carbon layer. Both require a certain amount to pass flammability tests; however, they often have limited compatibility with pressure-sensitive adhesive polymer materials, which can lead to poor adhesive performance. Similarly, the amount of inorganic flame retardant required to achieve a flame-retardant effect also affects the mechanical properties of pressure-sensitive adhesives, such as impact resistance and adhesive properties. Currently, there are attempts to improve the adhesion of flame-retardant tapes by chemically linking the flame retardant with the pressure-sensitive adhesive polymer to solve compatibility issues.

[0003] CN112812715B describes a flame-retardant pressure-sensitive adhesive comprising poly(meth)acrylate and organophosphorus compounds.

[0004] CN118580809A describes a high-temperature resistant and high-flame-retardant polyacrylate pressure-sensitive adhesive, which includes polyacrylate, epoxy cyclophosphonitrile, expanded graphite, and silane coupling agent.

[0005] However, there is currently no flame-retardant pressure-sensitive adhesive that simultaneously improves compatibility and impact resistance. The present invention aims to provide a high-temperature flame-retardant tape with good adhesive properties and impact resistance. Summary of the Invention

[0006] The purpose of this invention is to improve the flame retardancy of acrylic pressure-sensitive adhesives by chemically bonding organophosphorus compounds and polysiloxanes without using external flame retardants, while also enhancing the adhesion and impact resistance at high temperatures.

[0007] Solutions for solving technical problems

[0008] The first aspect of this invention provides a flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive, comprising, by weight, 80-95 parts of polyacrylate containing organophosphorus and polysiloxane side chains, 5-20 parts of tackifying resin, 80-150 parts of solvent and 0.1-1 parts of curing agent; wherein the polyacrylate containing organophosphorus and polysiloxane side chains is obtained by reacting a single-ended epoxy polysiloxane, an organophosphorus compound containing epoxy groups, and a carboxyl-containing polyacrylate.

[0009] The epoxy groups in single-ended epoxy polysiloxanes and organophosphorus compounds containing epoxy groups undergo ring-opening reactions with the carboxyl groups in carboxyl-containing polyacrylates, thereby covalently linking the polysiloxanes and organophosphorus compounds to the side chains of the polyacrylates. This linkage method avoids the migration of polysiloxane and organophosphorus groups due to poor compatibility, thus avoiding the impact of migration on adhesive strength. Both polysiloxanes and organophosphorus compounds are grafted onto the side chains of polyacrylate compounds through the reaction of carboxyl groups with epoxy groups, allowing for simultaneous "one-pot" reactions. The reactions are simple, easy to carry out, and produce few byproducts.

[0010] Preferably, the polyacrylate containing organophosphorus and polysiloxane side chains comprises, by weight, 5-20 parts of single-ended epoxy polysiloxane, 5-25 parts of organophosphorus compound containing epoxy groups, and 100-150 parts of carboxyl-containing polyacrylate (by solids).

[0011] Preferably, the single-ended epoxy polysiloxane is a polysiloxane with only one end having an epoxy group and side groups having methoxy, ethoxy, or alkyl groups, and has a molecular weight of 700-2000.

[0012] The molecular weight of the single-ended epoxy polysiloxane is limited to 700-2000, so that the foam tape containing it can have both impact resistance and system stability. If the molecular weight is lower than 700, it cannot form a microphase separation structure with the acrylate backbone, affecting its impact resistance. If the molecular weight is higher than 2000, the poor compatibility between the main and side chains will affect the system stability and durability.

[0013] More preferably, the single-ended epoxy polysiloxane is monoepoxy dimethyl polysiloxane (available for purchase at http: / / www.syktjdwx.com / product / 1411.html), with a molecular weight of 850-1300.

[0014] Preferably, the organophosphorus compound containing an epoxy group has one epoxy group and one or more organophosphorus groups, wherein the organophosphorus groups are selected from phosphonates and / or phosphine oxides.

[0015] More preferably, the organophosphorus compound containing an epoxy group is prepared by reacting a halogenated phosphate ester or a halogenated heterocyclic organophosphorus with glycidyl; the organophosphorus compound containing an epoxy group is selected from one or more of epoxidized phosphonates, epoxidized organophosphorus, and epoxidized heterocyclic organophosphorus.

[0016] Preferably, the carboxyl-containing polyacrylate has a weight-average molecular weight of 100,000 Da to 1,000,000 Da and contains 3-10 parts by weight of at least one carboxyl-containing acrylate monomer. The carboxyl-containing acrylate monomer includes, but is not limited to, long-chain (meth)acrylate compounds containing both unsaturated carbon-carbon double bonds and carboxyl groups, such as acrylic acid, methacrylic acid, maleic acid, oleic acid, and itaconic acid. In most embodiments, acrylic acid, methacrylic acid, or a mixture of the two are used.

[0017] To enable carboxyl-containing polyacrylates to have pressure-sensitive adhesive bonding capabilities, the glass transition temperature of carboxyl-containing polyacrylates is typically -55℃ to 5℃, preferably -45℃ to -20℃. If the glass transition temperature is too low, the peeling performance of the pressure-sensitive adhesive will be affected; if the glass transition temperature is too high, the bonding performance will be affected.

[0018] To enable carboxyl-containing polyacrylates to be used in pressure-sensitive adhesive applications, their monomers include at least one monomer with a homopolymer glass transition temperature below 20°C, i.e., a low-Tg monomer. The low-Tg monomer contains (meth)acrylates with four or more alkyl groups, such as ethyl acrylate, n-butyl (meth)acrylate, isooctyl acrylate, lauryl methacrylate, n-pentyl (meth)acrylate, and n-hexyl (meth)acrylate. The low-Tg monomer is present in 55-90 parts by weight in the carboxyl-containing polyacrylate.

[0019] Optionally, the carboxyl-containing polyacrylate includes one or more high-Tg monomers. High-Tg monomers refer to monomers with a homopolymer glass transition temperature greater than 30°C, such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, isobornyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, styrene and its substitutes, vinyl acetate, and propylene acetate. The high-Tg monomers in the carboxyl-containing polyacrylate are 5-15 parts by weight.

[0020] Optionally, the carboxyl-containing polyacrylate may also contain one or more functional monomers other than the carboxyl monomer, which must not react with the epoxy group and not interfere with the modification and curing of the acrylate polymer, such as hydroxyl monomers, amino monomers, and amide monomers, for example, hydroxyethyl acrylate, hydroxybutyl acrylate, and acrylamide. The weight parts of these monomers in the carboxyl-containing polyacrylate shall not exceed 5 parts.

[0021] Carboxylated polyacrylates typically contain one or more organic solvents to adjust the solid content to 15%-60%, including but not limited to one or more of ethyl acetate, butyl acetate, toluene, xylene, solvent oil, ethylene glycol butyl ether, etc.

[0022] Carboxylated polyacrylates are commonly polymerized using AIBN or BPO initiators, with a dosage of 1.0‰-7‰ of the total monomer amount.

[0023] Preparation method of carboxyl-containing polyacrylate:

[0024] Under the protection of inert gases such as nitrogen, the above-mentioned carboxyl-containing acrylate monomers, low-Tg monomers, possible high-Tg monomers, possible functional monomers and solvents are added and mixed evenly. The temperature is raised to 65-75℃, and 0.5‰-3‰ of the total monomer amount of initiator is added. After reacting for a period of time, 0.5‰-4‰ of the total monomer amount of initiator is added again. The temperature is maintained at 60-80℃ for 5-7 hours to obtain carboxyl-containing polyacrylate.

[0025] Preferably, the tackifying resin can be a terpene phenolic tackifying resin, or a tackifying resin such as rosin or modified rosin that has good compatibility with polyacrylate.

[0026] Preferably, solvent one is one or more organic solvents selected from ethyl acetate, n-butyl acetate, toluene, n-hexane, n-heptane, cyclohexane, methylcyclohexane, methyl ethyl ketone, methyl isobutyl ketone, etc.

[0027] Preferably, the curing agent can be one or more epoxy-type curing agents, or it can be used in combination with metal complexes or metal salt curing agents.

[0028] More preferably, the curing agent is one or more epoxy-type curing agents, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol triglycidyl ether, glycerol triglycidyl ether, etc.

[0029] The second invention provides a method for preparing a flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive, specifically including the following steps:

[0030] The tackifying resin is mixed and dispersed with a synthesized polyacrylate containing organophosphorus and polysiloxane side chains for more than 1 hour. After uniform dispersion, a curing agent is added and dispersion is continued for 10-20 minutes. A solvent is added to adjust the solid content, thus obtaining a flame-retardant, high-temperature resistant, and impact-resistant adhesive. The above adhesive is coated onto a PET release film and dried and cured to obtain a pressure-sensitive adhesive. The dry adhesive coating thickness can be 3-200 μm, and the curing conditions can be 48℃ for 48 hours, or curing at a higher temperature, generally not exceeding 120℃.

[0031] The third aspect of this invention provides the application of the flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive as described above in the bonding of the frame of 3C electronic products.

[0032] The beneficial effects of this invention are:

[0033] 1. A polyacrylate containing organophosphorus and polysiloxane side chains is synthesized by reacting a single-ended epoxy polysiloxane, an organophosphorus monomer containing an epoxy group, and a carboxyl-containing polyacrylic acid resin. The resulting polyacrylate containing organophosphorus and polysiloxane side chains is applied to a pressure-sensitive adhesive, giving the pressure-sensitive adhesive comprehensive properties such as flame retardancy, excellent adhesion at high temperatures, and good impact resistance.

[0034] 2. Single-ended epoxy polysiloxane and organophosphorus compounds containing epoxy groups are chemically linked to the main chain of carboxyl polyacrylic acid resin, and the two work together to achieve bulk flame retardancy.

[0035] 3. Single-ended epoxy polysiloxane has high temperature resistance, and its bonding performance remains excellent even when exposed to flammable and high-temperature environments.

[0036] 4. Polyacrylate containing organophosphorus and polysiloxane side chains is blended with tackifying resin. The polysiloxane with side chain branches forms a microphase separation structure with the polyacrylate. This structure can improve the impact resistance of pressure-sensitive adhesive. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Synthesis of organophosphorus compounds containing epoxy groups: Example 1: Synthesis of epoxidized phosphate esters

[0039] Add 50.5 g of 0.5 mol triethylamine to the flask to adjust the pH, 100 g of anhydrous toluene, and 22.4 g of 0.3 mol glycidyl ether to the flask. Place the flask in an ice-water bath and stir well. Slowly add a toluene solution of dimethyl chlorophosphate (36 g, 0.25 mol) dropwise over 1 hour. After the addition is complete, stir at room temperature overnight. Centrifuge to remove insoluble matter, and rotary evaporate to remove solvent and other residual reagents.

[0040] Synthesis Example 2 of Organophosphine Compounds Containing Epoxy Groups: Synthesis of Epoxidized Organophosphine

[0041] Add 50.5 g of 0.5 mol triethylamine to the flask to adjust the pH, 100 g of anhydrous toluene, and 22.4 g of 0.3 mol glycidyl. Place the flask in an ice-water bath and stir well. Slowly add a toluene solution of diphenylphosphine chloride (55 g, 0.25 mol) dropwise over 1 hour. After the addition is complete, stir at room temperature overnight. Centrifuge to remove insoluble matter, and rotary evaporate to remove solvent and other residual reagents.

[0042] Synthesis of organophosphorus compounds containing epoxy groups, Example 3: Synthesis of epoxidized heterocyclic organophosphorus compounds

[0043] Add 50.5 g of 0.5 mol triethylamine to the flask to adjust the pH, 100 g of anhydrous toluene, and 22.4 g of 0.3 mol glycidyl. Place the flask in an ice-water bath and stir well. Slowly add a toluene solution of 31.6 g of 2-chloro-1,3,2-dioxane-hexacyclopentane (0.25 mol) over 1 hour. After the addition is complete, stir overnight at room temperature. Centrifuge to remove insoluble matter and rotary evaporate to remove solvent and other residual reagents.

[0044] Example 1 of synthesis of carboxylated polyacrylate

[0045] In a four-necked reactor equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen inlet, add 900g of butyl acrylate, 50g of acrylic acid, 50g of methyl acrylate, and 1200g of ethyl acetate. While stirring, purge with nitrogen and heat to 65°C. Hold at this temperature for 5 minutes, then add 0.5g of AIBN (dissolved in 20g of ethyl acetate). Continue holding at 65°C. After 2 hours of reaction, add 0.25g of initiator AIBN for the first time, followed by 0.2g of initiator AIBN every 2 hours for the next 3 times. Continue the reaction for 1.5 hours, then stop heating and cool down. Add the remaining solvent, ethyl acetate, to adjust the solid content to 30% and disperse evenly.

[0046] The obtained carboxyl-containing polyacrylate had a glass transition temperature of -32.5℃ (measured by rotational rheometer) and a weight-average molecular weight of 8.85 × 10⁻⁶. 5 .

[0047] Example 2 of synthesis of carboxylated polyacrylate

[0048] In a four-necked reactor equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen inlet, add 650g of butyl acrylate, 50g of isooctyl acrylate, 30g of acrylic acid, 150g of methyl acrylate, and 1500g of ethyl acetate. While stirring, purge with nitrogen and heat to 65°C. Hold at this temperature for 5 minutes, then add 1g of AIBN (dissolved in 20g of ethyl acetate). Continue to hold at 65°C. After the reaction has proceeded for 2 hours, add 0.25g of initiator AIBN for the first time. Subsequently, add 0.2g of initiator AIBN three times every 2 hours. Raise the temperature to 75°C and reflux for 1 hour. Stop heating and cool down. Add the remaining solvent, ethyl acetate, to adjust the solid content to 30% and disperse evenly.

[0049] The obtained carboxyl-containing polyacrylate had a glass transition temperature of -21.3℃ (measured by rotational rheometer) and a weight-average molecular weight of 7.08 × 10⁻⁶. 5 .

[0050] Example 3 of synthesis of carboxylated polyacrylate

[0051] In a four-necked reactor equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen inlet, add 880g of butyl acrylate, 100g of methacrylic acid, 20g of hydroxyethyl acrylate, and 2200g of ethyl acetate. While stirring, purge with nitrogen and heat to 68°C. Hold at this temperature for 5 minutes, then add 1g of AIBN (dissolved in 20g of ethyl acetate). Continue to hold at 65°C. After 2 hours of reaction, add 0.5g of initiator AIBN for the first time, followed by 3 more additions of 0.3g of initiator AIBN every 2 hours. Heat to 75°C and reflux for 1 hour. Stop heating and cool down. Add the remaining solvent, ethyl acetate, to adjust the solid content to 30% and disperse evenly.

[0052] The obtained carboxyl-containing polyacrylate had a glass transition temperature of -20.9℃ (measured by rotational rheometer) and a weight-average molecular weight of 4.64 × 10⁻⁶. 5 .

[0053] Example 1

[0054] 1. Preparation of polyacrylates containing organophosphorus and polysiloxane side chains

[0055] 13g of epoxidized phosphate ester (Synthesis Example 1) and 15g of single-terminated epoxy dimethyl polysiloxane (purchased from Zhangjiagang Bangli Materials Technology Co., Ltd., product model SC-E01; the single-terminated epoxy dimethyl polysiloxane used in the following examples and comparative examples is the same as in Example 1) were added to 400g of carboxyl-containing polyacrylate solution of Synthesis Example 1 and stirred at room temperature for 24h to obtain polyacrylate containing organophosphine and polysiloxane side chains.

[0056] 2. Preparation of flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive

[0057] The polyacrylate containing organophosphorus and polysiloxane side chains was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:10:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0058] Example 2

[0059] 1. Preparation of polyacrylates containing organophosphorus and polysiloxane side chains

[0060] 25g of epoxidized phosphate ester (Synthesis Example 1) and 10g of single-terminated epoxy dimethyl polysiloxane were added to 400g of carboxyl-containing polyacrylate solution of Synthesis Example 1 and stirred at room temperature for 24h to obtain polyacrylate containing organophosphine and polysiloxane side chains.

[0061] 2. Preparation of flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive

[0062] The polyacrylate containing organophosphorus and polysiloxane side chains was mixed with tackifying resin TP7042 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:15:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0063] Example 3

[0064] 1. Preparation of polyacrylates containing organophosphorus and polysiloxane side chains

[0065] 20g of epoxidized organophosphine (Synthesis Example 2) and 5g of single-terminated epoxy dimethyl polysiloxane were added to 400g of carboxyl-containing polyacrylate solution from Synthesis Example 1 and stirred at room temperature for 24h to obtain polyacrylate containing organophosphine and polysiloxane side chains.

[0066] 2. Preparation of flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive

[0067] The above-mentioned polyacrylate containing organophosphorus and polysiloxane side chains was mixed with the tackifying resin SYLVALITE at a mass ratio of 90:15:0.05. TM RE 80HP and epoxy curing agent glycerol triglycidyl ether are mixed, and the solid content is adjusted to 20% with ethyl acetate. The mixture is then dispersed evenly using a three-roll mill to form a slightly yellow and transparent solution.

[0068] Example 4

[0069] 1. Preparation of polyacrylates containing organophosphorus and polysiloxane side chains

[0070] 10g of epoxidized organophosphorus (Synthesis Example 2) and 5g of single-terminated epoxy dimethyl polysiloxane were added to 500g of carboxyl-containing polyacrylate solution of Synthesis Example 2 and stirred at room temperature for 24h to obtain polyacrylate containing organophosphorus and polysiloxane side chains.

[0071] 2. Preparation of flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive

[0072] The polyacrylate containing organophosphorus and polysiloxane side chains was mixed with tackifying resin T95, epoxy curing agent glycerol triglycidyl ether and metal curing agent aluminum acetylacetonate in a mass ratio of 95:20:0.1:0.2. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0073] Example 5

[0074] 1. Preparation of polyacrylates containing organophosphorus and polysiloxane side chains

[0075] 15g of epoxidized heterocyclic organophosphine (Synthesis Example 3) and 10g of single-terminated epoxy dimethyl polysiloxane were added to 350g of carboxyl-containing polyacrylate solution of Synthesis Example 3 and stirred at room temperature for 24h to obtain polyacrylate containing organophosphine and polysiloxane side chains.

[0076] 2. Preparation of flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive

[0077] The polyacrylate containing organophosphorus and polysiloxane side chains was mixed with tackifying resin T95 and epoxy curing agent ethylene glycol diglycidyl ether at a mass ratio of 80:5:0.1. The solid content was adjusted to 25% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0078] Comparative Example 1

[0079] 1. Preparation of pressure-sensitive adhesive masterbatch mixture

[0080] 13g of dimethyl phosphate and 15g of dimethyl polysiloxane (purchased from Shanghai Zhenzhun Biotechnology Co., Ltd., Zhenzhun product number: 34036661) were added to 400g of carboxyl polyacrylate solution of the above synthesis example 1 and stirred at room temperature for 24h to obtain a mixture.

[0081] 2. Preparation of pressure-sensitive adhesive

[0082] The above mixture was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:10:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0083] Comparative Example 2

[0084] 1. Preparation of modified acrylate polymers

[0085] 28g of epoxidized phosphate ester (Synthesis Example 1) was added to 400g of carboxyl-containing polyacrylate solution of Synthesis Example 1 and stirred at room temperature for 24h to obtain modified acrylate polymer.

[0086] 2. Preparation of pressure-sensitive adhesive

[0087] The above polymer was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:10:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0088] Comparative Example 3

[0089] 1. Preparation of modified acrylate polymers

[0090] 28g of single-ended epoxy dimethyl polysiloxane was added to 400g of carboxyl-containing polyacrylate solution from the above synthesis example 1 and stirred at room temperature for 24h to obtain the modified acrylate polymer.

[0091] 2. Preparation of pressure-sensitive adhesive

[0092] The above polymer was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:10:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0093] Comparative Example 4

[0094] In a four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen inlet, add 90g of butyl acrylate, 5g of hydroxyethyl acrylate, 5g of methyl acrylate, and 120g of ethyl acetate. While stirring, purge with nitrogen and heat to 65°C, then maintain the temperature for 5 minutes. Add 0.05g of AIBN (dissolved in 2g of ethyl acetate) and continue to maintain the temperature at 65°C. After 2 hours of reaction, add 0.025g of initiator for the first time, followed by 0.02g of initiator AIBN every 2 hours thereafter. After two additions, continue the reaction for 1.5 hours, then stop heating and cool down. Add the remaining solvent, ethyl acetate, to adjust the solid content to 30% and disperse evenly to obtain a carboxyl-free polyacrylate solution.

[0095] 1. Preparation of modified acrylate polymers

[0096] 13g of epoxidized phosphonate (synthesis example 1) and 15g of single-terminated epoxy dimethyl polysiloxane were added to the above 400g of carboxyl-free polyacrylate solution and stirred at room temperature for 24h to obtain the modified acrylate polymer.

[0097] 2. Preparation of pressure-sensitive adhesive

[0098] The above polymer was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether at a mass ratio of 90:10:0.15. The solid content was adjusted to 20% with ethyl acetate and dispersed evenly with a three-roll mill to form a slightly yellow transparent solution.

[0099] Comparative Example 5

[0100] The preparation process of the pressure-sensitive adhesive is the same as in Example 1, except that the single-ended epoxy dimethyl polysiloxane of model SC-E01 is replaced with a single-ended epoxy dimethyl polysiloxane of model SC-E05 with a molecular weight of 5000.

[0101] The pressure-sensitive adhesives obtained in the above examples and comparative examples were coated on a PET release film with a thickness of 50 μm, dried to obtain a dry adhesive thickness of 50 μm, and cured in an oven at 48°C for 2 days to obtain the finished pressure-sensitive adhesive. The finished products were subjected to the following performance tests, and the test results are shown in the table below.

[0102]

[0103] The peel strength test was conducted in accordance with the standard "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014), and the substrate was SUS board.

[0104] The 85℃ peel strength was tested directly after the pressure-sensitive adhesive was prepared on the substrate according to the standard "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014) and placed at 85℃ for 24 hours; the 85℃ aging peel strength was tested after the pressure-sensitive adhesive was prepared on the substrate and placed at 85℃ for 7 days.

[0105] Drop hammer impact test: Impact resistance was measured according to ASTM D5628 in both the example and comparative cases, using a 180mm... 2 A 24.5mm*24.5mm*3mm SUS stainless steel sample was bonded to a 3mm 24.0mm 24.5mm*3mm SUS stainless steel sample with a U-shaped (outer frame 24.5mm, inner frame 20mm, 2.0mm width) pressure-sensitive adhesive to obtain the test sample. A 6.2kg weight was then placed on top of the sample for 10 seconds. The sample was left at room temperature for 48 hours before testing. The testing equipment was an Instron CEAST9340. The sample was impacted by dropping a 3.00kg (standard beam + weight) from a height of 100cm. The total impact energy required to release the adhesive from the SUS stainless steel substrate was measured and recorded.

[0106] Flame retardant performance was evaluated according to the UL94 vertical burning test method.

[0107] in conclusion:

[0108] In Examples 1-5 of this invention, an organophosphorus monomer containing an epoxy group and a single-ended epoxy polysiloxane are grafted onto a carboxyl-containing polyacrylate in the form of chemical bonds to prepare a polyacrylate containing organophosphorus and polysiloxane side chains. The pressure-sensitive adhesive obtained has high temperature resistance, flame retardancy and impact resistance.

[0109] Comparing Example 1 with Comparative Examples 1-4, it can be found that:

[0110] For Comparative Examples 1 and 4, which were directly blended, there was no epoxy-carboxyl group grafting reaction, resulting in poor compatibility and severe phase separation. At high temperatures, molecules migrated to the interface, leading to a significant decrease in high-temperature peel strength and a significant decrease in aging peel strength. Residual adhesive was also observed in both examples. However, no such phenomenon occurred in the examples linked by chemical bonds.

[0111] In Comparative Example 2, when no single-ended epoxy polysiloxane was added to the modified acrylate polymer, microphase separation was not formed, and its impact resistance was reduced. Since the flame retardant performance of the pressure-sensitive adhesive is affected by both the single-ended epoxy polysiloxane and the organophosphorus monomer containing epoxy groups, the organophosphorus monomer containing epoxy groups plays the main flame retardant role. Therefore, the flame retardant performance of the pressure-sensitive adhesive in Comparative Example 2 is V1.

[0112] In Comparative Example 3, the pressure-sensitive adhesive prepared without the addition of organophosphorus monomers containing epoxy groups had poor flame retardant properties. The absence of organophosphorus monomer modification also reduced the content of polar groups in the polyacrylate, resulting in a certain degree of reduction in the room temperature and high temperature peel strength of the pressure-sensitive adhesive.

[0113] In Comparative Example 5, the molecular weight of the single-ended epoxy dimethyl polysiloxane was 5000. Due to the poor compatibility of the main and side chains, the stability of the pressure-sensitive adhesive system was affected, and the peel strength at room temperature, peel strength at 85°C, and peel strength after 7 days of aging at 85°C all decreased significantly.

[0114] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flame-retardant high-temperature-resistant impact-resistant pressure-sensitive adhesive, characterized in that, The product comprises, by weight, 80-95 parts of polyacrylate containing organophosphorus and polysiloxane side chains, 5-20 parts of tackifying resin, 80-150 parts of solvent and 0.1-1 parts of curing agent; the polyacrylate containing organophosphorus and polysiloxane side chains is obtained by reacting a single-ended epoxy polysiloxane, an organophosphorus compound containing epoxy groups, and a carboxyl-containing polyacrylate. The polyacrylate containing organophosphorus and polysiloxane side chains comprises, by weight, 5-20 parts of single-ended epoxy polysiloxane, 5-25 parts of organophosphorus compound containing epoxy groups, and 100-150 parts of carboxyl-containing polyacrylate. The single-ended epoxy polysiloxane is a polysiloxane with only one end having an epoxy group and side groups of methoxy, ethoxy, or alkyl, and has a molecular weight of 700-2000.

2. The flame retardant, high temperature resistant, impact resistant pressure sensitive adhesive of claim 1, wherein, The single-ended epoxy polysiloxane is a monoepoxy dimethyl polysiloxane with a molecular weight of 850-1300.

3. The flame retardant, high temperature resistant, impact resistant pressure sensitive adhesive of claim 1, wherein, The organophosphorus compound containing an epoxy group has one epoxy group and one or more organophosphorus groups, wherein the organophosphorus groups are selected from phosphonates and / or phosphine oxides.

4. The flame retardant, high temperature resistant, impact resistant pressure sensitive adhesive of claim 1, wherein, The organophosphorus compound containing an epoxy group is prepared by reacting a halogenated phosphate ester or a halogenated heterocyclic organophosphorus compound with glycidyl.

5. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive according to claim 1, characterized in that, The organophosphorus compound containing an epoxy group is selected from one or more of epoxidized organophosphorus compounds and epoxidized heterocyclic organophosphorus compounds.

6. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive according to claim 1, characterized in that, The organophosphorus compound containing an epoxy group is an epoxide phosphonate.

7. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive according to claim 1, characterized in that, The carboxyl-containing polyacrylate has a weight-average molecular weight of 100,000 Da to 1,000,000 Da, a glass transition temperature of -55°C to 5°C, and a solid content of 15% to 60%. It contains 3-10 parts by weight of at least one carboxyl-containing acrylate monomer, 55-90 parts by weight of a low-Tg monomer, and an initiator accounting for 1-5‰ of the total monomers. The low-Tg monomer is a monomer with a homopolymer glass transition temperature of less than 20°C.

8. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive according to claim 7, characterized in that, The carboxyl-containing polyacrylate further includes 5-15 parts by weight of high Tg monomer and / or no more than 5 parts by weight of functional monomer, wherein the high Tg monomer is a monomer with a homopolymer glass transition temperature greater than 30°C.

9. The flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive according to claim 1, characterized in that, The tackifying resin is a terpene phenol, rosin, or modified rosin tackifying resin; the curing agent includes an epoxy curing agent.

10. A method for preparing a flame-retardant, high-temperature resistant, impact-resistant pressure-sensitive adhesive as described in any one of claims 1-9, specifically comprising the following steps: The tackifying resin is mixed and dispersed with the synthesized polyacrylate containing organophosphorus and polysiloxane side chains for more than 1 hour. After uniform dispersion, the curing agent is added and dispersion is continued for 10-20 minutes. Solvent is added to adjust the solid content to obtain a flame-retardant, high-temperature resistant and impact-resistant adhesive. The above adhesive is coated on a PET release film and dried and cured to obtain a pressure-sensitive adhesive.

11. The application of the flame-retardant, high-temperature resistant, and impact-resistant pressure-sensitive adhesive as described in any one of claims 1-9 in the bonding of the frame of 3C electronic products.

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