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

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, in particular to a flame-retardant, high-temperature-resistant and impact-resistant pressure-sensitive adhesive as well as a preparation method and application thereof. The flame-retardant, high-temperature-resistant and impact-resistant pressure-sensitive adhesive is prepared from the following components in parts by weight: 80 to 95 parts of polyacrylate containing organic phosphine and polysiloxane side chains, 5 to 20 parts of tackifying resin, 80 to 150 parts of a solvent I and 0.1 to 1 part of a curing agent, the polyacrylate containing the organic phosphine and the polysiloxane side chain is obtained by reacting single-ended epoxy polysiloxane, an organic phosphine compound containing an epoxy group and polyacrylate containing carboxyl. Under the condition that an additional flame retardant is not adopted, the organic phosphine compound is connected through chemical bonds, polysiloxane endows the acrylic pressure-sensitive adhesive with flame retardance, the flame retardance of the pressure-sensitive adhesive is improved, and meanwhile the adhesive strength and impact resistance at high temperature are improved.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to a flame-retardant, high-temperature-resistant and impact-resistant pressure-sensitive adhesive and a preparation method and application thereof. Background Art

[0002] Since the main component polymer of pressure-sensitive adhesive is flammable, flame retardants are often added to reduce the risk of fire in applications such as trains, cars, aircraft, electronics and electrical appliances in high temperature and flammable environments. At present, the commonly used flame retardants in the market include inorganic flame retardants, phosphorus flame retardants, nitrogen flame retardants, halogen flame retardants, silicon flame retardants, etc. Among them, halogen flame retardants are banned by many countries / organizations because they produce toxic and corrosive hydrohalic acid during the flame retardant process, which endangers human health; nitrogen flame retardants have poor flame retardant effects when used alone and need to be used in conjunction with phosphorus flame retardants. Phosphorus flame retardants mainly achieve flame retardant effects by forming isolation films, and silicon flame retardants mainly achieve flame retardant effects by generating cracked carbon layers and improving the oxidation resistance of carbon layers. Both need to reach a certain amount of addition to pass the flammability test. However, they often have limited compatibility with pressure-sensitive adhesive polymer materials, which will lead to poor adhesion performance of pressure-sensitive adhesives. Similarly, the loading amount of inorganic flame retardants required to achieve flame retardant effect will also affect the mechanical properties such as impact resistance and adhesive properties of pressure sensitive adhesive. At present, there have been attempts to solve the compatibility problem by linking flame retardants and pressure sensitive adhesive polymers through chemical bonds to improve the bonding ability of flame retardant tapes.

[0003] CN112812715B describes a flame retardant pressure-sensitive adhesive comprising poly(meth)acrylate and an organic phosphine compound.

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

[0005] However, there is currently no flame-retardant pressure-sensitive adhesive that has improved compatibility and impact resistance at the same time. The present invention aims to provide a high-temperature resistant flame-retardant adhesive tape with good adhesiveness and impact resistance. Summary of the invention

[0006] The purpose of the present invention is to impart flame retardancy to acrylic pressure-sensitive adhesive by chemically connecting organic phosphine compounds and polysiloxane without using an external flame retardant, thereby improving the flame retardancy of the pressure-sensitive adhesive and improving the adhesion and impact resistance at high temperatures.

[0007] Solutions for solving technical problems

[0008] The first aspect of the present invention provides a flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive, which comprises, by weight, 80-95 parts of polyacrylate containing organic phosphine and polysiloxane side chains, 5-20 parts of tackifying resin, 80-150 parts of solvent and 0.1-1 part of curing agent; the polyacrylate containing organic phosphine and polysiloxane side chains is obtained by reacting a single-end epoxy polysiloxane, an organic phosphine compound containing an epoxy group and a carboxyl-containing polyacrylate.

[0009] The epoxy groups in the single-ended epoxy polysiloxane and the epoxy-containing organic phosphine compound undergo a ring-opening reaction with the carboxyl groups in the carboxyl-containing polyacrylate, thereby linking the polysiloxane and the organic phosphine compound to the side chain of the polyacrylate through a covalent bond. This connection method avoids the migration of the polysiloxane and the organic phosphine group due to poor compatibility, thereby avoiding the influence of migration on the bonding ability; both the polysiloxane and the organic phosphine compound are grafted to the side chain of the polyacrylate compound through the reaction of the carboxyl group and the epoxy group, and can react simultaneously in a "one-pot method". The reaction is simple and easy to carry out, and there are few by-products.

[0010] Preferably, the polyacrylate containing organic phosphine and polysiloxane side chains comprises, by weight, 5-20 parts of single-end epoxy polysiloxane, 5-25 parts of organic phosphine compound containing epoxy group and 100-150 parts of carboxyl-containing polyacrylate (calculated as solid parts).

[0011] Preferably, the single-ended epoxy polysiloxane has only one end with an epoxy group and a side group with a methoxy group, an ethoxy group or an alkyl group, 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 main chain, affecting its impact resistance; if the molecular weight is higher than 2000, the system stability and durability are affected due to poor compatibility between the main and side chains.

[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 epoxy group-containing organic phosphine compound contains one epoxy group and one or more organic phosphine groups, and the organic phosphine groups are selected from phosphonates and / or phosphine oxides.

[0015] Further preferably, the epoxy group-containing organic phosphine compound is prepared from a halogen-containing phosphate or a halogen-containing heterocyclic organic phosphine and glycidol; the epoxy group-containing organic phosphine compound is selected from one or more of epoxidized phosphonates, epoxidized organic phosphines, and epoxidized heterocyclic organic phosphines.

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

[0017] In order to make the carboxyl-containing polyacrylate have pressure-sensitive adhesive bonding ability, the glass transition temperature of the carboxyl-containing polyacrylate is generally -55°C to 5°C, preferably -45°C to -20°C. If the glass transition temperature is too low, the peeling performance of the pressure-sensitive adhesive is affected, and if the glass transition temperature is too high, the bonding performance is affected.

[0018] In order to make the carboxyl-containing polyacrylate have the ability to be used as a pressure-sensitive adhesive, its monomers include at least one monomer whose homopolymer glass transition temperature is lower than 20°C, i.e., a low Tg monomer. The low Tg monomer includes a (meth)acrylate having an alkyl group of 4 or more carbon atoms, such as ethyl acrylate, n-butyl (meth)acrylate, isooctyl acrylate, lauryl methacrylate, n-pentyl (meth)acrylate, and n-hexyl (meth)acrylate. The weight portion of the low Tg monomer in the carboxyl-containing polyacrylate is 55-90 parts.

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

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

[0021] The carboxyl-containing polyacrylate usually contains 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 and the like.

[0022] Carboxyl-containing polyacrylates are usually polymerized with AIBN or BPO initiators, with the dosage being 1.0‰-7‰ of the total monomer amount.

[0023] Preparation method of carboxyl-containing polyacrylate:

[0024] Under the protection of an inert gas such as nitrogen, the above-mentioned carboxyl-containing acrylate monomer, low Tg monomer, possible high Tg monomer, possible functional monomer and solvent are added and mixed evenly, the temperature is raised to 65-75°C, an initiator with a total monomer amount of 0.5‰-3‰ is added, and after a period of reaction, an initiator with a total monomer amount of 0.5‰-4‰ is added, and the temperature is maintained at 60-80°C for 5-7h to obtain a carboxyl-containing polyacrylate.

[0025] Preferably, the tackifying resin may be a terpene phenol tackifying resin, or a tackifying resin such as rosin, modified rosin, etc. that has good compatibility with polyacrylate may be used.

[0026] Preferably, the solvent 1 is one or more organic solvents such as ethyl acetate, n-butyl acetate, toluene, n-hexane, n-heptane, cyclohexane, methylcyclohexane, methyl ethyl ketone, methyl isobutyl ketone, etc.

[0027] Preferably, the curing agent may be one or more epoxy curing agents, and may also be used in combination with a metal complex or a metal salt curing agent.

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

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

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

[0031] The third aspect of the present invention provides the use of the flame-retardant, high-temperature-resistant, impact-resistant pressure-sensitive adhesive described above in bonding the frames of 3C electronic products.

[0032] Beneficial effects of the present invention:

[0033] 1. A polyacrylate containing organic phosphine and polysiloxane side chains is synthesized by reacting single-ended epoxy polysiloxane, an organic phosphine monomer containing an epoxy group and a carboxyl-containing polyacrylic resin. The obtained polyacrylate containing organic phosphine and polysiloxane side chains is applied to a pressure-sensitive adhesive, so that the pressure-sensitive adhesive has the comprehensive properties of bulk flame retardancy, excellent adhesion at high temperature and good impact resistance.

[0034] 2. The single-ended epoxy polysiloxane and the organic phosphine compound containing epoxy group are chemically linked to the main chain of the carboxyl polyacrylic resin, and the two work together to achieve bulk flame retardancy.

[0035] 3. Single-ended epoxy polysiloxane is resistant to high temperatures and can maintain excellent bonding performance even in flammable and high-temperature environments.

[0036] 4. The polyacrylate containing organic phosphine and polysiloxane side chains is blended with a tackifying resin, and the polysiloxane grafted with the side chains forms a microphase separation structure with the polyacrylate, which can improve the impact resistance of the pressure-sensitive adhesive. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

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

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

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

[0042] Synthesis Example 3 of Organic Phosphine Compounds Containing Epoxy Groups: Synthesis of Epoxidized Heterocyclic Organic Phosphine

[0043] Add 50.5g 0.5mol triethylamine to the flask to adjust the pH, 100g anhydrous toluene, and 22.4g 0.3mol glycidol. Place the flask in an ice-water bath and stir evenly. Slowly add a toluene solution of 2-chloro-1,3,2-dioxophosphine heterocyclopentane (31.6g, 0.25mol) dropwise over 1h. After the addition is complete, stir at room temperature overnight, remove insoluble matter by centrifugation, and remove the solvent and other residual reagents by rotary evaporation.

[0044] Synthesis Example 1 of Carboxyl-containing Polyacrylate

[0045] Into a four-mouth reaction kettle equipped with mechanical stirring, thermometer, reflux condenser and nitrogen outlet, add 900 g of butyl acrylate, 50 g of acrylic acid, 50 g of methyl acrylate and 1200 g of ethyl acetate, stir and pass nitrogen, heat to 65°C and keep warm for 5 min, add 0.5 g of AIBN (dissolved in 20 g of ethyl acetate), continue to keep warm at 65°C, and add 0.25 g of initiator AIBN for the first time after the reaction has been carried out for 2 h, and then add initiator AIBN 3 times every 2 hours, each time adding 0.2 g. After continuing the reaction for 1.5 hours, stop heating and cool, add the remaining solvent ethyl acetate to adjust the solid content to 30%, and disperse evenly.

[0046] The prepared carboxyl-containing polyacrylate has a glass transition temperature of -32.5°C (measured by a rotational rheometer) and a weight-average molecular weight of 8.85×10 5 .

[0047] Synthesis Example 2 of Carboxyl-containing Polyacrylate

[0048] Into a four-mouth reaction kettle equipped with mechanical stirring, thermometer, reflux condenser and nitrogen outlet, add 650g of butyl acrylate, 50g of isooctyl acrylate, 30g of acrylic acid, 150g of methyl acrylate and 1500g of ethyl acetate, stir and pass nitrogen, heat to 65°C and keep warm for 5min, add 1g of AIBN (dissolved in 20g of ethyl acetate), continue to keep warm at 65°C, and add 0.25g of initiator AIBN for the first time after the reaction has been carried out for 2h, and then add 0.2g of initiator AIBN three times every 2 hours. Heat to 75°C, reflux reaction for 1 hour, stop heating and cool, add the remaining solvent ethyl acetate to adjust the solid content to 30%, and disperse evenly.

[0049] The prepared carboxyl-containing polyacrylate has a glass transition temperature of -21.3°C (measured by a rotational rheometer) and a weight-average molecular weight of 7.08×10 5 .

[0050] Synthesis Example 3 of Carboxyl-containing Polyacrylate

[0051] Into a four-mouth reaction kettle equipped with mechanical stirring, thermometer, reflux condenser and nitrogen outlet, add 880g of butyl acrylate, 100g of methacrylic acid, 20g of hydroxyethyl acrylate and 2200g of ethyl acetate, stir and pass nitrogen, heat to 68°C and keep warm for 5min, add 1g of AIBN (dissolved in 20g of ethyl acetate), continue to keep warm at 65°C, and add 0.5g of initiator AIBN for the first time after the reaction has been carried out for 2h, and then add 0.3g of initiator AIBN three times every 2 hours. After raising the temperature to 75°C and reflux reaction 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 prepared carboxyl-containing polyacrylate has a glass transition temperature of -20.9°C (measured by a rotational rheometer) and a weight-average molecular weight of 4.64×10 5 .

[0053] Example 1

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

[0055] 13 g of epoxidized phosphate (Synthesis Example 1) and 15 g of single-end epoxy dimethyl polysiloxane (purchased from Zhangjiagang Bangli Material Technology Co., Ltd., product model SC-E01, the following examples and comparative examples using single-end epoxy dimethyl polysiloxane are the same as Example 1) are added to 400 g of the carboxyl-containing polyacrylate solution of the above-mentioned Synthesis Example 1, stirred and reacted at room temperature for 24 hours to obtain a polyacrylate containing organic phosphine and polysiloxane side chains.

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

[0057] The polyacrylate containing organic phosphine and polysiloxane side chains was mixed with tackifying resin T110 and epoxy curing agent glycerol triglycidyl ether in 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 light yellow transparent solution.

[0058] Example 2

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

[0060] 25 g of epoxidized phosphate (Synthesis Example 1) and 10 g of single-end epoxydimethylpolysiloxane were added to 400 g of the carboxyl-containing polyacrylate solution of the above Synthesis Example 1, and stirred and reacted at room temperature for 24 hours to obtain a polyacrylate containing organic phosphine and polysiloxane side chains.

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

[0062] The polyacrylate containing organic phosphine and polysiloxane side chains was mixed with tackifying resin TP7042 and epoxy curing agent glycerol triglycidyl ether in 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 light yellow transparent solution.

[0063] Example 3

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

[0065] 20 g of epoxidized organic phosphine (Synthesis Example 2) and 5 g of single-end epoxydimethylpolysiloxane were added to 400 g of the carboxyl-containing polyacrylate solution of the above-mentioned Synthesis Example 1, and stirred and reacted at room temperature for 24 hours to obtain a polyacrylate containing organic phosphine and polysiloxane side chains.

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

[0067] The polyacrylate containing organic phosphine and polysiloxane side chains was mixed with tackifying resin SYLVALITE at a mass ratio of 90:15:0.05. TM RE 80HP and epoxy curing agent propylene glycol triglycidyl ether were mixed, the solid content was adjusted to 20% with ethyl acetate, and dispersed evenly with a three-roll mill to form a light yellow transparent solution.

[0068] Example 4

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

[0070] 10 g of epoxidized organic phosphorus (Synthesis Example 2) and 5 g of single-end epoxydimethylpolysiloxane were added to 500 g of the carboxyl-containing polyacrylate solution of the above Synthesis Example 2, and stirred and reacted at room temperature for 24 hours to obtain a polyacrylate containing organic phosphorus and polysiloxane side chains.

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

[0072] The above-mentioned polyacrylate containing organic phosphine 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 light yellow transparent solution.

[0073] Example 5

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

[0075] 15 g of epoxidized heterocyclic organic phosphine (Synthesis Example 3) and 10 g of single-end epoxydimethylpolysiloxane were added to 350 g of carboxyl-containing polyacrylate solution of the above Synthesis Example 3, and stirred and reacted at room temperature for 24 hours to obtain polyacrylate containing organic phosphine and polysiloxane side chains.

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

[0077] The polyacrylate containing organic phosphine and polysiloxane side chains was mixed with tackifying resin T95 and epoxy curing agent ethylene glycol diglycidyl ether in 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 light yellow transparent solution.

[0078] Comparative Example 1

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

[0080] 13 g of dimethyl phosphate and 15 g of dimethyl polysiloxane (purchased from Shanghai Zhenzhun Biotechnology Co., Ltd., Zhenzhun product number: 34036661) were added to 400 g of the carboxyl-containing polyacrylate solution of the above-mentioned Synthesis Example 1, and stirred at room temperature for reaction for 24 hours 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 in a mass ratio of 90:10:0.15, the solid content was adjusted to 20% with ethyl acetate, and the mixture was evenly dispersed with a three-roll mill to form a light yellow transparent solution.

[0083] Comparative Example 2

[0084] 1. Preparation of modified acrylate polymer

[0085] 28 g of epoxidized phosphate (Synthesis Example 1) was added to 400 g of the carboxyl group-containing polyacrylate solution of the above Synthesis Example 1, and the mixture was stirred and reacted at room temperature for 24 hours to obtain a 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 in a mass ratio of 90:10:0.15, the solid content was adjusted to 20% with ethyl acetate, and the mixture was evenly dispersed with a three-roll mill to form a light yellow transparent solution.

[0088] Comparative Example 3

[0089] 1. Preparation of modified acrylate polymer

[0090] 28 g of single-terminal epoxy dimethyl polysiloxane was added to 400 g of the carboxyl group-containing polyacrylate solution of the above-mentioned Synthesis Example 1, and the mixture was stirred and reacted at room temperature for 24 hours to obtain a 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 in a mass ratio of 90:10:0.15, the solid content was adjusted to 20% with ethyl acetate, and the mixture was evenly dispersed with a three-roll mill to form a light yellow transparent solution.

[0093] Comparative Example 4

[0094] In a four-necked flask equipped with mechanical stirring, a thermometer, a reflux condenser and a nitrogen outlet, 90 g of butyl acrylate, 5 g of hydroxyethyl acrylate, 5 g of methyl acrylate and 120 g of ethyl acetate were added, and nitrogen was passed through while stirring. After heating to 65°C and keeping warm for 5 min, 0.05 g of AIBN (dissolved in 2 g of ethyl acetate) was added, and the temperature was kept at 65°C. After the reaction was carried out for 2 hours, 0.025 g of initiator was added for the first time, and 0.02 g of initiator AIBN was added every 2 hours thereafter. After two additions, the reaction was continued for 1.5 hours, and then the heating was stopped and the temperature was lowered. The remaining solvent ethyl acetate was added to adjust the solid content to 30%, and the mixture was evenly dispersed. A polyacrylate solution free of carboxyl groups was obtained.

[0095] 1. Preparation of modified acrylate polymer

[0096] 13 g of epoxidized phosphonate (Synthesis Example 1) and 15 g of single-end epoxydimethylpolysiloxane were added to the above 400 g of the polyacrylate solution without carboxyl group, and stirred and reacted at room temperature for 24 hours to obtain a 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 in a mass ratio of 90:10:0.15, the solid content was adjusted to 20% with ethyl acetate, and the mixture was evenly dispersed with a three-roll mill to form a light yellow transparent solution.

[0099] Comparative Example 5

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

[0101] The pressure-sensitive adhesive obtained in the above embodiments and comparative examples was coated on a PET release film with a thickness of 50 μm, dried to obtain a dry adhesive with a thickness of 50 μm, and aged in an oven at 48°C for 2 days to obtain a 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 above peeling force test was carried out in accordance with the standard "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014), and the substrates were all SUS sheets.

[0104] The 85°C peel strength is the direct test after the pressure-sensitive adhesive is prepared on the substrate according to the "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014) and placed at a constant temperature of 85°C for 24 hours; the 85°C aging peel strength is the peel strength tested after the pressure-sensitive adhesive is prepared on the substrate and aged at 85°C for 7 days.

[0105] Drop hammer impact test: The impact resistance of the examples and comparative examples was measured according to ASTM D5628 using a 180 mm 2 The SUS stainless steel (24.5mm*24.5mm*3mm) was bonded to the 3mm SUS stainless steel (outer frame 40mm, inner frame 20mm) with a pressure-sensitive adhesive in the shape of a Chinese character (outer frame 24.5mm, inner frame 20.5mm, 2.0mm width) to obtain the sample to be tested, and then a 6.2Kg weight was placed on the top of the sample for 10 seconds. The sample was placed at room temperature for 48 hours before testing. The test equipment was Instron CEAST9340, which impacted the sample by dropping a 3.00Kg (standard beam + weight) from a height of 100cm, and the total impact energy (total energy) required to release the bond of the SUS stainless steel substrate was measured and recorded.

[0106] The flame retardant performance is evaluated according to the UL94 vertical burning test method.

[0107] in conclusion:

[0108] In Examples 1-5 of the present invention, an organic phosphine 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 an organic phosphine and a polysiloxane side chain. The pressure-sensitive adhesive finally obtained has high temperature resistance, flame retardancy, and impact resistance.

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

[0110] For the direct blending of Comparative Examples 1 and 4, there is no epoxy-carboxyl reaction grafting, the compatibility is poor, the phase separation is serious, and the molecules migrate to the interface at high temperature, resulting in a significant decrease in high-temperature peeling force and aging peeling force, and residual glue phenomenon. However, this phenomenon does not occur in the embodiments linked by chemical bonds.

[0111] In Comparative Example 2, when the single-ended epoxy polysiloxane is not added to the modified acrylate polymer, microphase separation is not formed and its impact resistance is reduced; because the flame retardant properties of the pressure-sensitive adhesive are affected by both the single-ended epoxy polysiloxane and the organic phosphine monomer containing an epoxy group, the organic phosphine monomer containing an epoxy group plays a major flame retardant role. Therefore, the flame retardant property of the pressure-sensitive adhesive in Comparative Example 2 is V1.

[0112] In Comparative Example 3, no epoxy group-containing organic phosphine monomer was added, and the prepared pressure-sensitive adhesive had poor flame retardant properties; without organic phosphine monomer modification, the polar group content in polyacrylate was also reduced, so the room temperature and high temperature peel strengths of the pressure-sensitive adhesive were reduced to a certain extent.

[0113] In Comparative Example 5, the molecular weight of the single-ended epoxy dimethyl polysiloxane is 5000. The poor compatibility of the main and side chains affects the stability of the pressure-sensitive adhesive system, and the room temperature peeling force, 85°C peeling force, and peeling force after aging at 85°C for 7 days all decrease significantly.

[0114] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive, characterized in that: The invention comprises 80-95 parts of polyacrylate containing organic phosphine and polysiloxane side chains, 5-20 parts of tackifying resin, 80-150 parts of solvent and 0.1-1 part of curing agent by weight. The polyacrylate containing organic phosphine and polysiloxane side chains is obtained by reacting single-end epoxy polysiloxane, organic phosphine compound containing epoxy group and carboxyl-containing polyacrylate.

2. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 1, characterized in that: The polyacrylate containing organic phosphine and polysiloxane side chains comprises, by weight, 5-20 parts of single-end epoxy polysiloxane, 5-25 parts of organic phosphine compound containing epoxy group and 100-150 parts of carboxyl-containing polyacrylate.

3. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 1 or 2, characterized in that: The single-ended epoxy polysiloxane has only one end with an epoxy group and a side group with a methoxy group, an ethoxy group or an alkyl group, and has a molecular weight of 700-2000.

4. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 1 or 2, characterized in that: The single-ended epoxy polysiloxane is monoepoxy dimethyl polysiloxane with a molecular weight of 850-1300.

5. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 1 or 2, characterized in that: The epoxy group-containing organic phosphine compound contains one epoxy group and one or more organic phosphine groups, wherein the organic phosphine groups are selected from phosphonates and / or phosphine oxides; the epoxy group-containing organic phosphine compound is prepared from halogen-containing phosphates or halogen-containing heterocyclic organic phosphines and glycidol; the epoxy group-containing organic phosphine compound is selected from one or more of epoxidized phosphonates, epoxidized organic phosphines, and epoxidized heterocyclic organic phosphines.

6. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 1 or 2, characterized in that: The carboxyl-containing polyacrylate has a weight average molecular weight of 100,000Da to 1,000,000Da, a glass transition temperature of -55°C to 5°C, a solid content of 15% to 60%, and comprises 3 to 10 parts by weight of at least one carboxyl-containing acrylate monomer, 55 to 90 parts by weight of a low Tg monomer, and an initiator accounting for 1 to 5‰ of the total monomer amount.

7. The flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive according to claim 6, characterized in that: The carboxyl-containing polyacrylate further comprises 5-15 parts by weight of a high Tg monomer and / or no more than 5 parts by weight of a functional monomer.

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

9. A method for preparing a flame retardant, high temperature resistant and impact resistant pressure sensitive adhesive, comprising the following steps: The tackifying resin and the synthesized polyacrylate containing organic phosphine and polysiloxane side chains are mixed and dispersed for more than 1 hour. After uniform dispersion, a curing agent is added and the dispersion is continued for 10-20 minutes. A solvent is added to adjust the solid content to obtain a flame-retardant, high-temperature, and impact-resistant glue. The above glue is coated on a PET release film and dried and cured to obtain a pressure-sensitive adhesive.

10. Application of a flame-retardant, high-temperature-resistant and impact-resistant pressure-sensitive adhesive in the bonding of 3C electronic product frames.

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