A flame-retardant high-peeling hot-curing structural adhesive, and an adhesive film and adhesive tape comprising the same

Abstract

The present application belongs to the field of structural adhesive and structural adhesive tape. A kind of flame-retardant high peel thermal curing structural adhesive, comprising the following raw materials by mass percentage: 20-60wt% of acrylic polymer;20-60wt% of epoxy resin composition;0.5-5wt% of curing agent;0.15-2.5wt% of accelerator;0.05-3wt% of photoinitiator;0-5wt% of multifunctional acrylic monomer;10-20wt% of flame retardant.The structural adhesive of the present application has initial adhesion at room temperature;Wide range of coating thickness;Can realize fast positioning;Long operating time;Meet the flame retardant requirements of UL94V0, with high shear strength;Can realize the firm connection of structure, also can achieve higher peel torque requirements, suitable for the structural parts bonding of automobile industry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of structural adhesive and structural adhesive tape, and particularly relates to a flame-retardant high-peeling thermosetting structural adhesive, and a film and a tape containing the same. BACKGROUND

[0002] CN106062020A discloses a thermosetting pressure-sensitive adhesive comprising a tacky polymer, a polyvinyl acetal, an epoxy resin and an epoxy resin curing agent. CN107709497A discloses a UV-curable epoxy / acrylate adhesive composition comprising a (meth)acrylic tetrahydrofurfuryl ester copolymer; an epoxy resin; a polyether polyol; and a hydroxyl-functional film-forming polymer. The adhesive can be used for structural and semi-structural bonding applications. The above-mentioned adhesive adopts a UV radical curing / thermal curing system, a UV cationic curing / thermal curing system; although better shear can be achieved between metals, between metals and glass, the obtained film needs low-temperature storage, which is not conducive to storage and transportation.

[0003] CN108300389A discloses an epoxy adhesive composition comprising: at least two kinds of epoxy resins; at least one bifunctional epoxy diluent; at least 3 kinds of toughening agents; at least one inorganic filler; at least one water removing agent; at least one thixotropic agent; at least one heat-activated latent curing agent; and at least one curing accelerator. The epoxy adhesive composition has high impact strength at room temperature and high temperature after curing, and can achieve the requirement of high peeling, but needs certain hot pressing for positioning, which reduces work efficiency.

[0004] CN112646536A discloses a two-component acrylic structural adhesive for bonding metal oily surfaces, which can directly bond metal oily surfaces and achieve high bonding strength (higher than 5N / mm) for bonding metal oily surfaces, and does not cause significant loss of solid content and environmental pollution problems during the curing process. However, its open time is short, it has certain corrosiveness to metal, and affects the electrochemical insulation stability.

[0005] In summary, the existing thermosetting structural adhesive has the following problems: it cannot be stored for a long time at room temperature, and the mechanical properties decrease significantly after a long time; the open time is short, the applicability is low, and it is not suitable for large-area or complex-structure bonding scenarios; hot pressing is needed for positioning, which easily damages the structure and reduces work efficiency, but if the strength of the structural adhesive is too high, it is not convenient to operate.

[0006] Therefore, there is a need for an adhesive tape that has certain pressure sensitivity before being attached, has a long open window before being attached, and can achieve the strength of a structural adhesive after a certain period of curing. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a flame-retardant high-peeling heat-cured structural adhesive, a film and a tape containing the same, the structural adhesive of the present application having initial adhesion at room temperature, a wide range of coatable thickness, fast positioning, long operation time, UL94 V0 flame-retardant requirements, high shear strength, structural firm connection, and high peeling torque requirements, and being suitable for structural component bonding in the automotive industry.

[0008] The technical solution adopted by the present application to solve the above problems is as follows:

[0009] A flame-retardant high-peeling heat-cured structural adhesive comprises the following preparation raw materials in mass percentage:

[0010] (I) 20-60wt% of an acrylic polymer;

[0011] (II) 20-60wt% of an epoxy resin composition;

[0012] (III) 0.5-5wt% of a curing agent;

[0013] (IV) 0.15-2.5wt% of an accelerator;

[0014] (V) 0.05-3wt% of a photoinitiator;

[0015] (VI) 0-5wt% of a multifunctional acrylic monomer;

[0016] (VII) 10-20wt% of a flame retardant.

[0017] Further, the mass ratio of the acrylic ester polymer and the epoxy resin composition is (3:7)-(7:3).

[0018] (I) 20-60wt% of an acrylic polymer:

[0019] Further, based on 100% of the acrylic polymer, the acrylic polymer comprises the following components in mass percentage: 60-90% of C1-C8 (meth) acrylic alkyl ester monomer; 10-30% of basic polymerizable vinyl monomer; 0-10% of cationic curable acrylic ester monomer; 0.01-1% of photoinitiator.

[0020] Further, the mass ratio of the C1-C8 (meth) acrylic alkyl ester monomer and the basic polymerizable vinyl monomer is 1-9:1.

[0021] Further, the C1-C8 (meth) acrylic alkyl ester monomer is at least one of (meth) acrylic methyl ester, (meth) acrylic ethyl ester, (meth) acrylic butyl ester, and (meth) acrylic isooctyl ester.

[0022] Preferably, the C1-C8 alkyl (meth)acrylate monomer is at least one of methyl (meth)acrylate and butyl (meth)acrylate.

[0023] Further, the basic polymerizable vinyl monomer is at least one of N-vinyl pyrrolidone and N-vinyl caprolactam.

[0024] Further, the cationically curable acrylate monomer is at least one of glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0025] Preferably, the cationically curable acrylate monomer is glycidyl acrylate.

[0026] Further, the photoinitiator is a free radical type photoinitiator; the free radical type photoinitiator is at least one of benzoin alkyl ether, acetophenone, benzophenone, dibenzoyl dimethyl ketal, and hydroxycyclohexyl phenyl ketone.

[0027] (II) 20-60 wt% of an epoxy resin composition:

[0028] Further, the epoxy resin composition comprises the following components in terms of mass percentage, based on 100% of the epoxy resin composition: 0-60% of a bisphenol A type liquid epoxy resin or a bisphenol F type liquid epoxy resin, 10-60% of a bisphenol A type solid epoxy resin, 0-10% of a dicyclopentadiene epoxy resin, and 5-40% of an epoxy toughener.

[0029] Further, the bisphenol A type liquid epoxy resin has an epoxy equivalent weight of 170-200; the bisphenol F type liquid epoxy resin has an epoxy equivalent weight of 160-180; the bisphenol A type solid epoxy resin has an epoxy equivalent weight of 500-1200; and the dicyclopentadiene type epoxy resin has an epoxy equivalent weight of 240-290.

[0030] Further, the epoxy toughener is at least one of a core-shell toughened epoxy resin, a CTBN toughened epoxy resin, a polyurethane toughened epoxy resin, and a blocked high-temperature deblocked polyurethane resin.

[0031] Preferably, the epoxy toughener is a CTBN toughened epoxy resin and a blocked high-temperature deblocked polyurethane resin.

[0032] (III) 0.5-5 wt% of a curing agent:

[0033] Further, the curing agent is at least one of diaminodiphenyl sulfone and dicyandiamide.

[0034] (IV) 0.15-2.5 wt% of an accelerator:

[0035] Further, the accelerator is at least one of a modified imidazole accelerator, a modified amine accelerator, and a modified urea accelerator.

[0036] Preferably, the accelerator is preferably a modified urea accelerator.

[0037] (V) 0.05-3 wt% of a photoinitiator:

[0038] Further, the photoinitiator is a free radical photoinitiator; the free radical photoinitiator is at least one of benzoin alkyl ether, acetophenone, benzophenone, dibenzoyl dimethyl ketal, and hydroxycyclohexyl phenyl ketone.

[0039] (VI) 0-5 wt% of a multifunctional acrylic monomer:

[0040] Further, the multifunctional acrylic monomer is at least one of a difunctional acrylic monomer and a trifunctional acrylic monomer.

[0041] Preferably, the multifunctional acrylic monomer is one or two of 1,6-hexanediol diacrylate, di(propylene glycol) diacrylate, tri(propylene glycol) diacrylate, and trimethylolpropane triacrylate.

[0042] (VII) 10-20 wt% of a flame retardant:

[0043] Further, the flame retardant includes a liquid phosphate ester flame retardant and a solid phosphate ester flame retardant; the liquid phosphate ester flame retardant accounts for 3-10 wt% of the mass of the flame retardant.

[0044] Further, the flame-retardant high-peel thermosetting structural adhesive further includes the following component materials: a silane coupling agent, a thixotropic agent, and a reaction inhibitor.

[0045] Further, the silane coupling agent is at least one of KH-560, KH-570, KH-550, and A-187.

[0046] Further, the reaction inhibitor is at least one of methyl p-toluenesulfonate, phosphoric acid, and borate ester. When low-temperature curing is used, the addition of the reaction inhibitor helps to preserve stability and curing promotion, ensuring curing activity.

[0047] Further, the thixotropic agent is at least one of fumed silica and hydrogenated castor oil. The thixotropic agent selected in the present application can ensure the stability of the material in the coating process, ensuring the shape of the coating.

[0048] Preferably, the thixotropic agent is hydrophilic fumed silica. The hydrophilic fumed silica can improve the stability of the material in a hot and humid environment, ensuring the consistency of the performance of the material under various environmental conditions.

[0049] Further, the flame-retardant high-peel heat-cured structural adhesive further comprises the following raw materials by mass percentage: 0.5-2wt% of silane coupling agent, 0.05-1wt% of reaction inhibitor, and 0.05-5wt% of thixotropic agent.

[0050] A film, comprising the flame-retardant high-peel heat-cured structural adhesive as described above.

[0051] Further, the film has a thickness of 0.03-1mm.

[0052] The present application also provides a tape, comprising the film as described above.

[0053] The present application has the following advantages:

[0054] The heat-cured structural adhesive of the present application can be stored stably at room temperature, has initial adhesion at room temperature, has a wide range of coating thickness, can meet the requirements of different coating thicknesses, can achieve rapid positioning, and has a long operation time. The heat-cured structural adhesive of the present application meets the flame-retardant requirements of UL94 V0, has high shear strength, can maintain stable bonding performance under various stress conditions, can achieve not only structural firm connection but also high peel torque requirements for bonding between metals and metals or metals and plastics, is suitable for bonding of structural parts in the automotive industry, and can meet the high requirements of the industry on material strength, flame retardancy, and stability. The structural adhesive has a clear color change reaction before and after heat curing, which provides a direct basis for customers to judge the curing effect of the product, and through the color change indication, the product abnormalities caused by poor curing can be effectively reduced, and the production efficiency and product quality can be improved. DETAILED DESCRIPTION

[0055] The technical solutions of the present application will be further described below through specific embodiments. It should be understood that those skilled in the art can conceive other various embodiments and make modifications according to the teachings of the present application without departing from the scope or spirit of the present disclosure. Therefore, the following specific embodiments are not limiting in nature.

[0056] Unless otherwise specified, the test materials, reagents, methods, and equipment used in the present application are conventional test materials, reagents, methods, and equipment in the technical field; unless otherwise specified, the test materials and reagents used in the present application can be obtained from commercial channels.

[0057] The application provides a fire-retardant high-peeling heat-cured structural adhesive, which comprises the following component raw materials in percentage by mass:

[0058] (I) 20-60wt% of an acrylic polymer;

[0059] (II) 20-60wt% of an epoxy resin composition;

[0060] (III) 0.5-5wt% of a curing agent;

[0061] (IV) 0.15-2.5wt% of an accelerator;

[0062] (V) 0.05-3wt% of a photoinitiator;

[0063] (VI) 0-5wt% of a multifunctional acrylic monomer;

[0064] (VII) 10-20wt% of a fire retardant.

[0065] In some specific embodiments of the application, the mass ratio of the acrylic ester polymer and the epoxy resin composition is (3:7)-(7:3).

[0066] (I) 20-60wt% of an acrylic polymer:

[0067] In some specific embodiments of the application, the acrylic polymer comprises the following components in percentage by mass, based on 100% of the acrylic polymer: 60-90% of C1-C8 alkyl (meth)acrylate monomer; 10-30% of basic polymerizable vinyl monomer; 0-10% of cationic curable acrylic monomer; and 0.01-1% of photoinitiator.

[0068] In some specific embodiments of the application, the mass ratio of the C1-C8 alkyl (meth)acrylate monomer and the basic polymerizable vinyl monomer is 1-9:1.

[0069] In the above technical solution, the acrylic polymer is a polymer of C1-C8 alkyl (meth)acrylate monomer, basic polymerizable vinyl monomer and cationic curable acrylic monomer, and a photoinitiator needs to be added simultaneously during the polymerization process.

[0070] Specifically, the C1-C8 alkyl (meth)acrylate monomer can be selected from, but is not limited to, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid iso-octyl ester and the like.

[0071] In some preferred embodiments of the present application, the C1-C8 alkyl (meth)acrylate monomer is at least one of methyl (meth)acrylate and butyl (meth)acrylate.

[0072] In the above technical solution, the basic polymerizable vinyl monomer specifically refers to a polymerizable vinyl monomer containing a basic group in its molecular structure; specifically, the basic polymerizable vinyl monomer can be selected from, but is not limited to, N-vinyl caprolactam, N-vinyl pyrrolidone, (meth) acryloyl morpholine, (meth) acrylamide, N,N-dimethyl (meth) acrylamide, N,N-diethyl (meth) acrylamide, (meth) acrylonitrile, etc.

[0073] In some preferred embodiments of the present application, the basic polymerizable vinyl monomer is at least one of N-vinyl caprolactam and N-vinyl pyrrolidone. Specifically, the cationically curable acrylate monomer can be selected from, but is not limited to, glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc.

[0074] In some preferred embodiments of the present application, the cationically curable acrylate monomer is glycidyl acrylate.

[0075] In some specific embodiments of the present application, the photoinitiator is a free radical type photoinitiator; the free radical type photoinitiator is at least one of benzoin alkyl ether, acetophenone, benzophenone, dibenzoyl dimethyl ketal, and hydroxycyclohexyl phenyl ketone.

[0076] Specifically, the free radical type photoinitiator can be selected from, but is not limited to, Irgacure 819, Irgacure 651, Darocur 1173, TPO, etc.

[0077] (II) 20-60 wt% of an epoxy resin composition:

[0078] In some specific embodiments of the present application, the epoxy resin composition comprises the following components in terms of mass percentage, based on 100% of the epoxy resin composition: 0-60% of a bisphenol A type liquid epoxy resin or a bisphenol F type liquid epoxy resin, 10-60% of a bisphenol A type solid epoxy resin, 0-10% of a dicyclopentadiene epoxy resin, and 5-40% of an epoxy toughening agent.

[0079] In the above technical solution, if the content of the liquid epoxy resin is higher than 60wt%, the glue surface of the obtained structural adhesive will be sticky, and the cohesive strength will be poor; if the content of the solid epoxy resin is lower than 10wt%, the surface of the obtained structural adhesive after curing will be sticky, if the content of the solid epoxy resin is higher than 60wt%, the strength of the obtained structural adhesive will decrease; if the content of the dicyclopentadiene epoxy resin is higher than 10wt%, the obtained structural adhesive will be hard, and the peel strength will not increase obviously. If the content of the epoxy toughening agent is lower than 5wt%, the peel strength of the obtained structural adhesive is insufficient, and if the content of the epoxy toughening agent is higher than 40wt%, there is a risk of glue overflow.

[0080] In some embodiments of the present application, the epoxy equivalent weight of the liquid bisphenol A type epoxy resin is 170-200; the epoxy equivalent weight of the liquid bisphenol F type epoxy resin is 160-180; the epoxy equivalent weight of the solid bisphenol A type epoxy resin is 500-1200; and the epoxy equivalent weight of the dicyclopentadiene type epoxy resin is 240-290.

[0081] Specifically, the liquid bisphenol A type epoxy resin can be selected from, but is not limited to, DER331, EPON945, EPON1001F, etc.

[0082] Specifically, the solid bisphenol A type epoxy resin can be selected from, but is not limited to, NPES901.

[0083] Specifically, the dicyclopentadiene type epoxy resin can be selected from, but is not limited to, XD1000 of Japan Chemical Medicine, HP7200 of DIC, etc.

[0084] Specifically, the liquid bisphenol F type epoxy resin can be selected from, but is not limited to, EPON862, etc.

[0085] In some embodiments of the present application, the epoxy toughening agent is at least one of a core-shell toughening type epoxy resin, a CTBN toughening type epoxy resin, a polyurethane toughening type epoxy resin, and a blocked high-temperature deblocked polyurethane resin.

[0086] In some preferred embodiments of the present application, the epoxy toughening agent is a CTBN toughening type epoxy resin and a blocked high-temperature deblocked polyurethane resin.

[0087] Specifically, the core-shell toughening type epoxy resin can be selected from, but is not limited to, MX125, MX154, MX257, etc. of Zhongyuan.

[0088] Specifically, the CTBN toughening type epoxy resin can be selected from, but is not limited to, CTBN 1300X13, etc. of Hensman.

[0089] Specifically, the polyurethane toughened epoxy resin can be selected from, but is not limited to, ERS-133 and ERS-DC11 of Shanghai Zhongsi.

[0090] Specifically, the capped high-temperature deblocking polyurethane resin can be selected from, but is not limited to, QR9466 of ADEKA.

[0091] (III) 0.5-5 wt% of a curing agent;

[0092] In some embodiments of the present application, the curing agent is at least one of diaminodiphenyl sulfone and dicyandiamide.

[0093] Specifically, the dicyandiamide can be selected from, but is not limited to, Dyhard 100S of Wanhua; and the diaminodiphenyl sulfone can be selected from, but is not limited to, 4,4'-diaminodiphenyl sulfone and 3,3'-diaminodiphenyl sulfone.

[0094] In the above technical solution, if the content of the curing agent is less than 0.5 wt%, the obtained structural adhesive is not cured enough; and if the content of the curing agent is more than 5 wt%, the obtained structural adhesive is too hard after curing, and the peelability is poor.

[0095] (IV) 0.15-2.5 wt% of an accelerator;

[0096] In some embodiments of the present application, the accelerator is at least one of a modified imidazole accelerator, a modified amine accelerator and a modified urea accelerator.

[0097] In some preferred embodiments of the present application, the accelerator is preferably a modified urea accelerator.

[0098] Specifically, the modified imidazole accelerator can be selected from, but is not limited to, 2E4MZ and 2MZ-A of Shikoku Chemicals, PN-23, PN-H and PN-40.

[0099] Specifically, the modified amine accelerator can be selected from, but is not limited to, FXR-1020 and FXR-1081.

[0100] Specifically, the modified urea accelerator can be selected from, but is not limited to, Dyhard UR300 and Dyhard UR500 of Wanhua.

[0101] In the above technical solution, if the content of the accelerator is less than 0.15 wt%, the obtained structural adhesive is cured slowly; and if the content of the accelerator is more than 2.5 wt%, the storage stability of the structural adhesive is affected.

[0102] (V) 0.05-3 wt% of a photoinitiator;

[0103] In some embodiments of the present application, the photoinitiator is a free radical photoinitiator; the free radical photoinitiator is at least one of benzoin alkyl ether, acetophenone, benzophenone, dibenzoyl-methanol, hydroxycyclohexyl phenyl ketone.

[0104] Specifically, the free radical photoinitiator can be selected from, but not limited to, Irgacure 819, Irgacure 651, Darocur 1173, TPO, etc.

[0105] (Ⅵ) 0-5 wt% of a multifunctional acrylic monomer;

[0106] In some embodiments of the present application, the multifunctional acrylic monomer is at least one of a difunctional acrylic monomer, a trifunctional acrylic monomer.

[0107] Specifically, the multifunctional acrylic monomer can be selected from, but not limited to, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, etc.

[0108] In some preferred embodiments of the present application, the multifunctional acrylic monomer is one or two of 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate.

[0109] (Ⅶ) 10-20 wt% of a flame retardant;

[0110] In some embodiments of the present application, the flame retardant includes a liquid phosphoric acid ester flame retardant and a solid phosphoric acid ester flame retardant; the liquid phosphoric acid ester flame retardant accounts for 3-10 wt% of the mass of the flame retardant.

[0111] In the above technical solution, the flame retardant selected is a halogen-free flame retardant. If the content of the liquid phosphoric acid ester flame retardant is less than 3 wt% of the flame retardant, the effect of reducing the viscosity of the system is not obvious, and the processing performance of the material cannot be effectively improved; if it is higher than 10 wt% of the flame retardant, it will act as a plasticizer, resulting in a decrease in the shear strength and peel strength of the material.

[0112] Specifically, the liquid phosphoric acid ester flame retardant can be selected from, but not limited to, Japan Daiba CR-733S.

[0113] Specifically, the solid phosphoric acid ester flame retardant can be selected from, but not limited to, Clariant OP930, Clariant OP935.

[0114] In some embodiments of the present application, the flame-retardant high-peel thermosetting structural adhesive further comprises the following constituent raw materials: a silane coupling agent, a thixotropic agent, a reaction inhibitor.

[0115] Specifically, the silane coupling agent can be selected from, but not limited to, at least one of KH-560, KH-570, KH-550, and A-187. The coupling agent selected in the present application helps to form a good bonding interface between different materials, enhances or improves the bonding effect between different materials, thereby improving the bonding reliability.

[0116] Specifically, the reaction inhibitor is selected from, but not limited to, at least one of methyl p-toluenesulfonate, phosphoric acid, and borate. When low-temperature curing is adopted, the addition of the reaction inhibitor helps to save the stability and curing promotion, and ensures the curing activity.

[0117] In some preferred embodiments of the present application, the borate is selected from tributyl borate.

[0118] In some specific embodiments of the present application, the thixotropic agent is at least one of fumed silica and hydrogenated castor oil. The thixotropic agent selected in the present application can ensure the stability of the material in the coating process, and ensure the coating shape.

[0119] In some preferred embodiments of the present application, the thixotropic agent is hydrophilic fumed silica. The hydrophilic fumed silica can improve the stability of the material in a humid heat environment, and ensure the performance consistency of the material under various environmental conditions.

[0120] Specifically, the hydrophilic fumed silica can be selected from, but not limited to, WACKER AEROSIL A200.

[0121] In some specific embodiments of the present application, the flame-retardant high-peel thermosetting structural adhesive further comprises the following raw materials in terms of mass percentage: 0.5-2wt% of the silane coupling agent, 0.05-1wt% of the reaction inhibitor, and 0.05-5wt% of the thixotropic agent.

[0122] The present application provides a film, which comprises the flame-retardant high-peel thermosetting structural adhesive as described above.

[0123] Further, the thickness of the film is 0.03-1mm.

[0124] The present application further provides a tape, which comprises the film as described above.

[0125] In the present application, the adhesive film / tape is formed from the structural adhesive of the present application. Exemplarily, the adhesive film / tape can be formed by hot extrusion or melt extrusion. More specifically, the structural adhesive of the present application can be first extruded by hot or melt onto a flexible or non-flexible substrate (including release film), and the adhesive film is formed by UV curing; the adhesive tape structure provided by the present application can be respectively compounded with release film on the front and back surfaces of the adhesive film, or only compounded with release film on one surface of the adhesive film.

[0126] The present application will be described in more detail below with reference to examples. It should be noted that these descriptions and examples are for the purpose of facilitating the understanding of the present application, and are not limitations of the present application.

[0127] The raw materials used in the present application are shown in Table 1.

[0128] Table 1 Raw material information:

[0129]

[0130]

[0131] Table 2 Raw material usage (unit: wt%) of Examples 1-4 and Comparative Examples 1-2:

[0132]

[0133]

[0134] The present application does not limit the preparation method of the above-mentioned structural adhesive, and the structural adhesive of the present application can be prepared by conventional methods for preparing structural adhesives in the art, such as conventional mixing and stirring.

[0135] Specifically, the preparation method of the structural adhesive of the examples and comparative examples includes: first, mixing raw materials 2EHA, BA, NVC, GMA and Irgacure651(1) according to the amount shown in Table 2 to obtain a mixture; then irradiating the obtained mixture with a 0.5 mW / cm 2 of ultraviolet light, stopping irradiation when the viscosity of the mixture is 1000-3000 mpa.s; then adding the remaining raw materials according to the amount shown in Table 2 to obtain the structural adhesive.

[0136] The structural adhesive obtained from the examples and comparative examples is respectively applied to a transparent PET release film, and then covered with another piece of transparent PET release film. Determine the appropriate thickness, and irradiate the sheet-shaped adhesive with a 0.5 mW / cm 2 of ultraviolet light to obtain the adhesive film of the examples and comparative examples.

[0137] The adhesive films prepared in Examples 1 to 4 and Comparative Examples 1 to 2, a domestic adhesive film product (selected as a structural adhesive film of Sika, model MF1009) and an international adhesive film product (selected as a structural adhesive film of 3M, model 9214) were subjected to the following performance tests, respectively.

[0138] (1) Storage stability:

[0139] At room temperature, the PET release film on one side of the adhesive film was torn off, and a 25 μm PET backing was attached (placed in an environment of 25°C for at least 1 day); then the sample was taken out and cut into a width of 12.7 mm and a length of at least 120 mm, and was attached to a mirror-finished steel plate using a 5 kg press roller for one pass, and was left to stand at room temperature for 20 min, and then was subjected to a 90° peeling force test at a speed of 300 mm / min.

[0140] After the preparation of the structural adhesive composition, the peeling force after the line was cut and after storage in an environment of 25°C for 180 days was tested, and the storage stability of the structural adhesive was evaluated according to the following evaluation criteria:

[0141] “PASS” indicates that the room temperature 90° peeling force decreases by 5% or less; and “NG” indicates that the room temperature 90° peeling force decreases by more than 5%. The evaluation results are shown in Table 3.

[0142] (2) Thickness change rate before and after curing and product appearance color:

[0143] The thickness change rate = (thickness after curing - thickness before curing) / thickness before curing * 100%; a positive thickness change rate indicates that the adhesive film expands after curing; and a negative thickness change rate indicates that the adhesive film shrinks after curing. The results are shown in Table 4. The color change of the structural adhesive film after thermal curing was observed, and the results are shown in Table 5.

[0144] (3) Elongation at break (%) and breaking strength (MPa):

[0145] The two conditions of before and after curing were treated; the adhesive film was cut into a width of 5 mm and a length of 60 mm, and was tested using a universal material testing machine at a speed of 500 mm / min; and the results are shown in Table 6.

[0146] (4) Shear strength:

[0147] Preparation before testing: 5052 anodized aluminum plate (without sandblasting treatment), size 30*75 mm, thickness 3 mm. The surface of the plate was cleaned with IPA or ethanol, and after the sample was prepared, it was attached using a 5 kg press for 10 s.

[0148] 4.1. Initial 20 min

[0149] Prepare 10*25mm adhesive film sample at room temperature, then immediately adhere it on aluminum plate, 5kg roller back and forth once, place it in room temperature environment for 20mins, set the tensile tester speed at 50mm / min, test its shear strength.

[0150] 4.2. 24hrs at room temperature

[0151] Prepare 10*25mm adhesive film sample, place it in 140℃ / 30mins environment, after taking it out, place it in room temperature environment for 24hrs, set the tensile tester speed at 50mm / min, test its shear strength and take photo to record failure mode.

[0152] 4.3. Heat aging

[0153] Prepare 10*25mm adhesive film sample (after curing), place it in 80℃ / 672hrs environment, after taking it out, place it in room temperature environment for 24hrs, set the tensile tester speed at 50mm / min, test its shear strength and take photo to record failure mode.

[0154] 4.4. Hot water soaking

[0155] Prepare 10*25mm adhesive film sample (after curing), place it in hot water bath 50℃ / 672hrs environment, after taking it out, place it in room temperature environment for 24hrs, test its shear strength at 50mm / min speed.

[0156] 4.5. High temperature and high humidity

[0157] Prepare 10*25mm adhesive film sample (after curing), place it in high temperature and high humidity 50℃ / 95%RH / 672hrs environment, after taking it out, place it in room temperature environment for 24hrs, set the tensile tester speed at 50mm / min, test its shear strength and take photo to record failure mode.

[0158] 4.6. High temperature 80℃

[0159] Prepare 10*25mm adhesive film sample (after curing), place it in high temperature 80℃ environment for 30mins, then test its shear strength at 80℃ temperature with tensile tester speed set at 50mm / min and take photo to record failure mode.

[0160] 4.7. Low temperature -40℃

[0161] Prepare 10*25mm adhesive film sample (after curing), place it in low temperature -40℃ environment for 30mins, then test its shear strength at -40℃ temperature with tensile tester speed set at 50mm / min and take photo to record failure mode.

[0162] The above results are shown in Table 7.

[0163] (5) Static Creep Test:

[0164] Test Preparation: Zinc alloy round mirror base, structural adhesive film die-cut piece (5 cm 2 ).

[0165] The metal mirror base was cleaned with alcohol, and then the die-cut adhesive film part was immediately and evenly pasted on the metal mirror base (2 kg pressure, 5 s). The prepared adhesive part was bonded to the glass surface at room temperature with a pressure of 5 kg / cm 2 (27.5 kg) for 10 s, and then the part temperature was raised to about 140°C for 30 min for curing. After one day at room temperature, the prepared cured adhesive part was used for testing. The part was placed in an anti-creep fixture for testing, and the loading conditions were as follows:

[0166] 5.1. High temperature with 1.0 kg load

[0167] Test fixture, angle adjustment to 45°, then load 1 kg weight, set dry oven conditions to 80°C, test time 30 days, record drop-off time, before and after test photos (visible on the bonding surface), and calculate the percentage of shedding.

[0168] 5.2. High humidity with 2.7 kg load

[0169] Test fixture, angle adjustment to 45°, then load 2.7 kg weight, set environmental chamber conditions to 50°C / 95% RH, test time 125 days, record drop-off time, before and after test photos (visible on the bonding surface), and calculate the percentage of shedding.

[0170] 5.3 High humidity with 4.0 kg load

[0171] Test fixture, angle adjustment to 45°, then load 4.0 kg weight, set environmental chamber conditions to 50°C / 95% RH, test time 80 days, record drop-off time, before and after test photos (visible on the bonding surface), and calculate the percentage of shedding.

[0172] The above results are shown in Table 8.

[0173] (6) Component peel torque test:

[0174] Test Preparation: Zinc alloy shield mirror base, structural adhesive film die-cut piece (5 cm 2 , suitable for shield mirror base).

[0175] The shield mirror base was cleaned with alcohol, and then the die-cut adhesive film part was immediately and evenly pasted on the metal mirror base (2 kg pressure, 5 s). The prepared adhesive part was bonded to the glass surface at room temperature with a pressure of 5 kg / cm 2(27.5kg) pressure on the glass surface, 10s, 20min room temperature, 140°C, 30min curing (the whole part temperature to 140°C start timing), take out the room temperature for a day, the prepared cured with glue parts, put into the peel torque tool, with a tensile speed of 50mm / min test, load conditions as follows:

[0176] 6.1 room temperature 24hrs

[0177] The prepared with glue parts at room temperature with 5kg / cm 2 (27.5kg) pressure on the glass surface, 10s, 20min room temperature, 140°C, 30min curing (the whole part temperature to 140°C start timing), take out the room temperature for a day, the prepared cured with glue parts, put into the peel torque tool, with a tensile speed of 50mm / min test, load conditions as follows:

[0178] 6.2. Cold and hot cycle

[0179] The prepared sample, placed in the cold and hot cycle conditions for 90°C (2hrs), 23°C (0.5hr), -40°C (2hrs), 23°C (0.5hr), run 10 cycles, take out the room temperature for 1hr, put into the peel torque tool for testing.

[0180] 6.3. Hot water immersion

[0181] The prepared sample, placed in the 50°C, 336hrs warm water, take out the surface moisture, room temperature for 1hr, put into the peel torque tool for testing.

[0182] 6.4. High temperature and humidity

[0183] The prepared sample, placed in the 50°C, 95%RH, 336hrs environment, take out the room temperature for 1hr, put into the peel torque tool for testing.

[0184] 6.5. W.O.M xenon lamp aging

[0185] The prepared sample, the glass surface of the non-component bonding towards the xenon lamp, aging conditions for 550W / ㎡, 120min sun, 10min water cycle, a total of 1000hrs, take out the room temperature for 1hr, put into the peel torque tool for testing.

[0186] 6.6 Low temperature -40°C

[0187] The prepared adhesive film sample, placed in the -40°C, 8hrs environment, take out the room temperature for 1hr, put into the peel torque tool for testing.

[0188] The above results are shown in Table 9.

[0189] (7) 1600N torque impact:

[0190] The high torque impact test was performed on the base part of the automobile front mirror and the front windshield as test objects.

[0191] The prepared adhesive part was attached to the glass surface at room temperature under a pressure of 5 kg / cm 2 (27.5 kg) for 10 seconds, and then the temperature was raised to 140°C for 30 minutes, and the sample was cured under the condition of a 1 kg weight (the oven and the weight were heated to 140°C, and the total number of samples was preferably 16 or less), and then the sample was taken out and left at room temperature for one day, and then the sample was loaded into a torque test jig, and a torque of 68 N.m (about 1600 N.cm) was applied to the lever at a position of 130 mm therefrom for 1 minute, and then the test was performed, and the damage to the sample was recorded.

[0192] The above results are shown in Table 10.

[0193] (8) Flame retardant test

[0194] The adhesive films prepared from Examples 1 to 3 and Comparative Examples 1 and 2 were made into samples of 12.5 mm*80 mm together with domestic and international products, and then the samples were tested before curing and after curing at 140°C for 30 minutes under a pressure of 0.3 MPa, and then the samples were left at room temperature for 30 minutes, and then the flame retardant test was performed. The results are shown in Table 11.

[0195] Table 3 Storage stability

[0196]

[0197] Table 4 Thickness change rate of heat-cured structural adhesive film

[0198] Sample Initial thickness Thicknes after heat cure Rate of thickness change Example 1 0.51 0.555 8.80％ Example 2 0.505 0.555 9.90％ Example 3 0.5 0.545 9％ Comparative Example 1 0.512 0.535 4.45％ Comparative Example 2 0.523 0.543 3.80％ Domestic product 0.519 0.583 12.40％ International product 0.48 0.522 8.90％

[0199] Table 5 Color change of heat-cured structural adhesive film after heat curing

[0200]

[0201]

[0202] Table 6 Cured breaking strength and elongation of heat-cured structural adhesive film

[0203]

[0204] Table 7 Shear strength (MPa) of heat-cured structural adhesive film

[0205]

[0206]

[0207] Table 8 Static Creep Test of Heat Cured Structural Adhesive Film (MPa)

[0208]

[0209] Table 9 Component Peel Torque Test of Heat Cured Structural Adhesive Film (N*M)

[0210]

[0211] Table 10 1600N Torque Impact of Heat Cured Structural Adhesive Film

[0212] Test environment Room temperature Example 1 100% of bonded parts had no drop or damage (glass was not broken) Example 2 100% of bonded parts had no drop or damage Example 3 100% of bonded parts had no drop or damage Comparative Example 1 100% of bonded parts dropped Comparative Example 2 100% of bonded parts dropped Domestic product 100% of bonded parts dropped (glass was not broken) International product 100% of bonded parts had no drop or damage (glass was not broken)

[0213] Table 11 Flame Retardant Test of Heat Cured Structural Adhesive Film

[0214]

[0215] From the test results of the above table, it can be seen that the heat cured structural adhesive has a significant thickness change rate, which is more conducive to the assembly tolerance control of parts; the color of the heat cured structural adhesive changes significantly before and after curing, indicating that the adhesive film undergoes chemical reaction under heat, and the bonding condition and curing degree can be preliminarily judged in real time; the heat cured structural adhesive has excellent performance before and after curing, and has good elongation at break and breaking strength. The heat cured structural adhesive film introduces dicyclopentadiene phenol epoxy resin and capped high-temperature unblocking polyurethane resin, realizes high shear strength of the adhesive film after heat curing, and realizes a peel force torque of metal and glass of 45N*m or more, which is significantly higher than similar international and domestic products; by adding liquid flame retardant and solid flame retardant, the purpose of halogen-free flame retardation is achieved; while meeting strong bonding, the safety performance of the automobile product is obviously improved, and it is suitable for the increasing application demand of the automobile industry.

[0216] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0217] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again by the present application.

[0218] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A flame retardant high peel heat cured structural adhesive characterized by, The composition raw materials include the following components by mass percentage: (I) 20-60 wt% of an acrylic polymer; (II) 20-60 wt% of an epoxy resin composition; (III) 0.5-5 wt% of a curing agent; (IV) 0.15-2.5 wt% of an accelerator; (V) 0.05-3 wt% of a photoinitiator; (VI) 0-5 wt% of a multifunctional acrylic monomer; (VII) 10-20 wt% of a flame retardant; The acrylic polymer, taking 100% of the acrylic polymer as a basis, includes the following components by mass percentage: 60-90% of C1-C8 alkyl (meth) acrylate monomers; 10-30% of basic polymerizable vinyl monomers; 0-10% of cationically curable acrylic monomers; 0.01-1% of a photoinitiator; The C1-C8 alkyl (meth) acrylate monomers are at least one of (meth) acrylate and (meth) acrylate; The basic polymerizable vinyl monomer is N-vinyl pyrrolidone; The epoxy resin composition, taking 100% of the epoxy resin composition as a basis, includes the following components by mass percentage: 0-60% of a bisphenol A type liquid epoxy resin or a bisphenol F type liquid epoxy resin, 10-60% of a bisphenol A type solid epoxy resin, 2.4-10% of a dicyclopentadiene epoxy resin, and 5-40% of an epoxy toughening agent; The epoxy toughening agent is a capped high-temperature deblocking polyurethane resin.

2. The flame retardant high peel hot cure structural adhesive of claim 1, wherein, The accelerator is at least one of a modified imidazole accelerator, a modified amine accelerator, and a modified urea accelerator.

3. The flame retardant high peel hot cure structural adhesive of claim 1, wherein, The multifunctional acrylic monomer is at least one of a difunctional acrylic monomer and a trifunctional acrylic monomer.

4. The flame retardant high peel hot cure structural adhesive of claim 1, wherein, The composition raw materials further include a silane coupling agent, a thixotropic agent, and a reaction inhibitor.

5. An adhesive film, characterized by The flame-retardant high-peeling thermosetting structural adhesive includes the flame-retardant high-peeling thermosetting structural adhesive according to any one of claims 1-4.

6. An adhesive tape, characterized by The adhesive film includes the adhesive film according to claim 5.

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