Two-component synergistic flame-retardant modified toughened epoxy adhesive and preparation method thereof

Abstract

A two-component synergistic flame-retardant modified toughening epoxy adhesive and its preparation method are disclosed. The adhesive is divided into component A and component B, which are stored separately. When used, component A and component B are mixed at a mass ratio of 100:80-150 and cured by heating. By mass, component A comprises: a base epoxy resin, a biphenyl-type phenolic epoxy resin, and surface-modified silica. By mass, component B comprises: an anhydride curing agent, surface-modified silica, and anthracene methyl quaternary ammonium salt additive. The introduced biphenyl structure possesses both flame-retardant and char-forming properties; the anthracene methyl quaternary ammonium salt additive can catalyze char formation and release non-flammable gases during combustion. The synergistic effect of these two components significantly improves flame-retardant performance, meeting the high flame-retardant requirements of motor packaging; the rigid structure of the biphenyl-type phenolic epoxy resin can disperse stress under external forces, achieving toughening.

Description

Technical Field

[0001] This invention relates to a two-component adhesive and its preparation method, specifically to a two-component flame-retardant toughened epoxy adhesive and its preparation method. Background Technology

[0002] Motors continuously generate heat during operation, and their internal circuitry is dense. If the adhesive's flame retardancy is insufficient, it can easily ignite a fire. Therefore, the flame retardancy requirements for motor encapsulation adhesives are far higher than those for ordinary industrial adhesives. While existing epoxy adhesives can meet basic bonding needs, they have significant shortcomings: some adhesives do not meet motor encapsulation standards for flame retardancy. Even with the addition of flame retardants to improve flame retardancy, poor compatibility between the flame retardant and the resin matrix often leads to uneven dispersion, reducing adhesive toughness and causing brittleness. Furthermore, most products struggle to simultaneously improve heat resistance, thermal conductivity, flame retardancy, and toughening properties, making them unsuitable for the harsh environment of long-term high-temperature motor operation. Therefore, there is an urgent need for an epoxy adhesive that can simultaneously address the issues of flame retardancy, toughening, and synergistic performance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide an epoxy adhesive that has both toughening and flame retardant properties.

[0004] The technical solution adopted by the present invention to solve its technical problem is as follows: a two-component synergistic flame retardant modified toughening epoxy adhesive, which is divided into component A and component B and stored separately. When using, component A and component B are mixed at a mass ratio of 100:80~150 and then heated to cure.

[0005] By weight, the raw materials of component A include: 65-75 parts of matrix epoxy resin, 10-25 parts of biphenyl-type phenolic epoxy resin, and 150-250 parts of surface-modified silica; wherein the biphenyl-type phenolic epoxy resin has a biphenyl structure.

[0006] By weight, the raw materials of component B include: 70-100 parts of acid anhydride curing agent, 150-250 parts of surface-modified silica, and 1-15 parts of anthracene methyl quaternary ammonium salt additive;

[0007] The anthracene methyl quaternary ammonium salt adjuvant includes:

[0008] , At least one of the following; wherein:

[0009] R is selected from C1~C12 alkyl groups;

[0010] R' is selected from H, C1~C12 alkyl, C1~C12 alkoxy, substituted aryl, unsubstituted aryl, substituted aryloxy, and unsubstituted aryloxy.

[0011] R 1 ~R 4 Each is independently selected from H, halogen, C1~C12 alkyl, C1~C12 alkoxy, substituted aryl, unsubstituted aryl, substituted aryloxy, and unsubstituted aryloxy.

[0012] X is selected from halogens, nitrates, acetates, sulfates, trifluoromethanesulfonates, fluoroborates, and fluoroantimonates.

[0013] Preferably, the matrix epoxy resin is a polyepoxy functional group glycidyl ether epoxy resin.

[0014] Preferably, the matrix epoxy resin includes one or more of bisphenol A, bisphenol F, bisphenol S, and phenolic epoxy resin.

[0015] Preferably, the biphenyl-type phenolic epoxy resin includes one or more of tetramethylbiphenyl diphenol type epoxy resin, biphenyl phenol type epoxy resin, and biphenyl aralkyl phenolic resin.

[0016] Preferably, the anhydride curing agent is selected from one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride.

[0017] Preferably, the modifier for the surface-modified silica is... R1 and R2 are each independently selected from hydroxyl groups or C1-C12 alkyl alcohols.

[0018] Preferably, the particle size of the surface-modified silica is 1 μm to 15 μm.

[0019] Preferably, the method for preparing the surface-modified silica includes:

[0020] Silica with physically adsorbed water removed from its surface is mixed with anhydrous toluene containing 1 wt% to 5 wt% modifier under an inert atmosphere to form a hydrogen-bonded complex pre-adsorption system. Then, under an inert atmosphere, at a temperature of 140℃ to 180℃ and a pressure of 2 MPa to 4 MPa, the mixture is stirred for 3 to 6 hours to obtain surface-modified silica.

[0021] Preferably, the raw materials of component A further include 0-10 parts of dispersant, 0-5 parts of colorant, and 0-10 parts of diluent.

[0022] Preferably, the raw materials of component B also include 0-2 parts of accelerator and 0-10 parts of dispersant.

[0023] More preferably, the diluent is a phenyl glycidyl ether and / or an allyl glycidyl ether compound.

[0024] More preferably, the dispersant is a non-solvent-type high molecular weight wetting and dispersing agent.

[0025] More preferably, the colorant includes one or more of carbon black, titanium dioxide, and iron oxide red.

[0026] More preferably, the accelerator is an imidazole accelerator.

[0027] Based on the same inventive concept, the present invention also provides a method for preparing the two-component synergistic flame-retardant modified toughened epoxy adhesive, wherein component A and component B are respectively prepared by uniformly mixing their corresponding raw materials.

[0028] Preferably, during the preparation of component A, the matrix epoxy resin and biphenyl-type phenolic epoxy resin are preheated to 80°C to 120°C before mixing, and the mixing of the remaining raw materials is carried out below 80°C.

[0029] Preferably, during the preparation of component B, the raw materials are mixed at a temperature below 80°C.

[0030] The present invention has the following beneficial effects:

[0031] This solution uses biphenyl-type phenolic epoxy resin, and the introduced biphenyl structure possesses flame retardancy and char-forming properties. The anthracene methyl quaternary ammonium salt additive can catalyze char formation and release non-flammable gases during combustion. The synergistic effect of the two can significantly improve the flame retardant performance, meeting the high flame retardant requirements of motor packaging. In the adhesive of this invention, the biphenyl-type phenolic epoxy resin can also form a supramolecular ordered structure through π-π self-assembly, giving the adhesive high intrinsic thermal conductivity. Its rigid structure can improve heat resistance, making the adhesive less likely to reach the ignition point in the high-temperature environment of the motor, extending its service life, and dispersing the stress under external force to achieve toughening.

[0032] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 The TM1 manufactured in the embodiments of the present invention 1 H-NMR spectrum;

[0035] Figure 2 The TM1 manufactured in the embodiments of the present invention 13 C-NMR spectrum;

[0036] Figure 3 The TM2 manufactured in the embodiments of the present invention1 H-NMR spectrum;

[0037] Figure 4 The TM2 manufactured in the embodiments of the present invention 13 C-NMR spectrum. Detailed Implementation

[0038] To make the objectives, solutions, and beneficial technologies of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be noted that the embodiments described in this specification are merely illustrative of the invention and are not intended to limit the invention.

[0039] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0040] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, "multiple" in "one or more" means two or more, and "more than" in "one or more" means two or more.

[0041] An embodiment of the present invention provides a two-component synergistic flame-retardant modified toughening epoxy adhesive, which is divided into component A and component B and stored separately. When using, component A and component B are mixed at a mass ratio of 100:80~150 and then cured by heating.

[0042] By weight, the raw materials of component A include: 65-75 parts of matrix epoxy resin, 10-25 parts of biphenyl-type phenolic epoxy resin, and 150-250 parts of surface-modified silica; wherein the biphenyl-type phenolic epoxy resin has a biphenyl structure.

[0043] By weight, the raw materials of component B include: 70-100 parts of acid anhydride curing agent, 150-250 parts of surface-modified silica, and 1-15 parts of anthracene methyl quaternary ammonium salt additive;

[0044] The anthracene methyl quaternary ammonium salt adjuvant includes:

[0045] , At least one of the following; wherein:

[0046] R is selected from C1~C12 alkyl groups;

[0047] R' is selected from H, C1~C12 alkyl, C1~C12 alkoxy, substituted aryl, unsubstituted aryl, substituted aryloxy, and unsubstituted aryloxy.

[0048] R 1 ~R 4 Each is independently selected from H, halogen, C1~C12 alkyl, C1~C12 alkoxy, substituted aryl, unsubstituted aryl, substituted aryloxy, and unsubstituted aryloxy.

[0049] X is selected from halogens, nitrates, acetates, sulfates, trifluoromethanesulfonates, fluoroborates, and fluoroantimonates.

[0050] This solution uses biphenyl-type phenolic epoxy resin, the introduced biphenyl structure possessing flame retardancy and char-forming properties; anthracene methyl quaternary ammonium salt additive can catalyze char formation and release non-flammable gases during combustion. The synergistic effect of these two significantly improves flame retardancy, meeting the high flame retardancy requirements of motor packaging. In the adhesive of this invention, the biphenyl-type phenolic epoxy resin can also form a supramolecular ordered structure through π-π self-assembly, endowing the adhesive with high intrinsic thermal conductivity. Its rigid structure improves heat resistance, making the adhesive less likely to reach its ignition point under high-temperature motor conditions, extending its service life, and dispersing stress under external forces, thus achieving toughening. However, excessive addition of biphenyl-type phenolic epoxy resin can lead to excessively rigid molecular chains, causing the adhesive to become brittle. Therefore, an appropriate ratio should be maintained with the base epoxy resin. Surface modification of silica can reduce agglomeration, improve the compatibility of components, and enhance interfacial bonding.

[0051] In embodiments of the present invention, the matrix epoxy resin is a polyepoxy functional group glycidyl ether epoxy resin.

[0052] In embodiments of the present invention, the matrix epoxy resin includes one or more of bisphenol A, bisphenol F, bisphenol S, and phenolic epoxy resin.

[0053] In embodiments of the present invention, the biphenyl-type phenolic epoxy resin includes one or more of tetramethylbiphenyl diphenol type epoxy resin, biphenyl phenol type epoxy resin, and biphenyl aryl phenolic resin.

[0054] In embodiments of the present invention, the anhydride curing agent is selected from one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride.

[0055] In an embodiment of the present invention, the modifier of the surface-modified silica is... R1 and R2 are each independently selected from hydroxyl groups or C1-C12 alkyl alcohols. This modifier has a biphenyl structure similar to that of biphenyl-type phenolic epoxy resin, which can help the biphenyl-type phenolic epoxy resin disperse stress under external force and achieve toughening. Because it also has a biphenyl structure, it has good compatibility with biphenyl-type phenolic epoxy resin and strong interfacial bonding force, avoiding debonding problems during use.

[0056] In an embodiment of the present invention, the particle size of the surface-modified silica is 1 μm to 15 μm.

[0057] In an embodiment of the present invention, the method for preparing the surface-modified silica includes:

[0058] Silica with physically adsorbed water removed from its surface is mixed with anhydrous toluene containing 1 wt% to 5 wt% modifier under an inert atmosphere to form a hydrogen-bonded complex pre-adsorption system. Then, under an inert atmosphere, at a temperature of 140℃ to 180℃ and a pressure of 2 MPa to 4 MPa, the mixture is stirred for 3 to 6 hours to obtain surface-modified silica.

[0059] In embodiments of the present invention, the raw materials of component A further include 0-10 parts of dispersant, 0-5 parts of colorant, and 0-10 parts of diluent.

[0060] In embodiments of the present invention, the raw materials of component B further include 0-2 parts of accelerator and 0-10 parts of dispersant.

[0061] In some embodiments of the present invention, the diluent is a phenyl glycidyl ether and / or an allyl glycidyl ether compound.

[0062] In some embodiments of the present invention, the dispersant is a non-solvent-type high molecular weight wetting and dispersing agent.

[0063] In some embodiments of the present invention, the colorant includes one or more of carbon black, titanium dioxide, and iron oxide red.

[0064] In some embodiments of the present invention, the accelerator is an imidazole accelerator.

[0065] The preparation method of the two-component synergistic flame-retardant modified and toughened epoxy adhesive described in this embodiment of the invention involves mixing component A and component B uniformly from their respective raw materials.

[0066] In an embodiment of the present invention, during the preparation of component A, the matrix epoxy resin and biphenyl-type phenolic epoxy resin are preheated to 80°C to 120°C before mixing, and the mixing of the remaining raw materials is carried out below 80°C.

[0067] In an embodiment of the present invention, the raw materials are mixed at a temperature below 80°C during the preparation of component B.

[0068] Example

[0069] The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight. Unless otherwise stated, all reagents used in the examples are available commercially or synthesized using conventional methods and are ready for use without further processing. Unless otherwise stated, all instruments used in the examples are available commercially.

[0070] (I) Preparation of surface-modified silica

[0071] The methods for preparing surface-modified silica in each embodiment are as follows:

[0072] (1) Take a small amount of silica and place it in a vacuum drying oven. Dry it at 120°C for 6 hours to remove the surface physically adsorbed water. Cool it to room temperature and set it aside. In a dry 250mL three-necked flask, add 100mL of anhydrous toluene and then slowly add 3g of modifier. Stir magnetically for 10 minutes until completely dissolved to form a homogeneous modifier solution.

[0073] (2) The dried silica was slowly added to the modifier solution and stirred at room temperature for 3 hours under nitrogen protection to ensure the formation of a stable hydrogen bond complex pre-adsorption system. Then it was transferred to a high-pressure reactor. Before sealing, the air inside the reactor was replaced with nitrogen three times to ensure a water-free and oxygen-free environment inside the reactor. The reaction temperature was set to 160℃ and the pressure inside the reactor was increased to 2.5MPa. The reaction was stirred for 5 hours. The high temperature and high pressure will promote the conversion of the hydrogen bond complex into Si-O-Si covalent bonds.

[0074] (3) After the reaction is completed, the product is naturally cooled to room temperature, the pressure inside the vessel is released, and the reaction product is taken out. The product is washed three times by centrifugation with anhydrous toluene. Then the solid is placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain hydroxyl-functionalized surface-modified silica.

[0075] (II) Preparation of anthracene methyl quaternary ammonium salt auxiliaries

[0076] Anthracene methyl quaternary ammonium salt auxiliaries can be prepared by reacting haloanthracene with an amino functional group. The specific preparation methods are described below using TM1 and TM2 as examples. The anthracene methyl quaternary ammonium salt auxiliaries in this scheme have similar properties. Those skilled in the art, based on this and combined with common knowledge in the field, can use similar methods to obtain other anthracene methyl quaternary ammonium salt auxiliaries. Structural formulas of TM1 and TM2:

[0077] (abbreviated as TM1) (abbreviated as TM2).

[0078] (1) Preparation of TM1

[0079] The reaction formula for preparing TM1 can be written as:

[0080] ;

[0081] The specific preparation method of TM1 is as follows:

[0082] Under a nitrogen atmosphere, 5 mmol of 9-chloromethylanthracene was dissolved in 5 mL of dry methanol in a round-bottom flask equipped with a magnetic stirrer, followed by the dropwise addition of 15 mmol of a 30% trimethylamine solution. The reaction was refluxed at 70 °C for a certain period of time. After the reaction was completed as monitored by TLC, a large amount of dichloromethane was added to the reaction flask until the solution became clear. After standing at room temperature for 24 h, a solid precipitated out. The product was filtered to obtain yellow crystals, with a yield of 85%.

[0083] Figure 1 It's TM1. 1 H-NMR spectrum; 1 H NMR (400 MHz, CD3OD): δ 8.51 (s, 1H), 8.39 (d, J =9.02 Hz, 2H), 7.95 (d, J = 8.65 Hz, 2H), 7.58 (t, J = 7.97 Hz, 1H), 7.42 (t, J =8.04 Hz, 2H), 5.53 (s, 2H), 3.00 (s, 9H).

[0084] Figure 2 It's TM1. 13 C-NMR spectrum; 13 C NMR (100 MHz, CD3OD): δ 134.2, 133.4, 132.7, 130.9, 129.2, 126.5, 125.1, 119.6, 61.1, 54.3.

[0085] (2) Preparation of TM2

[0086] The reaction formula for preparing TM2 can be written as:

[0087] ;

[0088] The specific preparation method of TM2 is as follows:

[0089] Under a nitrogen atmosphere, 9,10-dichloromethylanthracene (5 mmol) was dissolved in 5 mL of dry methanol in a round-bottom flask equipped with a magnetic stirrer, followed by the dropwise addition of a 30% trimethylamine solution (15 mmol). The reaction was refluxed at 70 °C for a certain period of time. After the reaction was completed as monitored by TLC, a large amount of dichloromethane was added to the reaction flask until the solution became clear. After standing at room temperature for 24 h, a solid precipitated out. The product was filtered to obtain yellow crystals, with a yield of 82%.

[0090] Figure 3 It's TM2. 1 H-NMR spectrum; 1 H NMR (400 MHz, CD3OD): δ 7.04 (d, J = 10.28 Hz, 4H), 6.23 (d, J = 10.12 Hz, 4H), 4.05 (s, 4H), 1.58 (s, 18H).

[0091] Figure 4 It's TM2. 13 C-NMR spectrum; 13 C NMR (100 MHz, CD3OD): δ 133.6, 129.0, 126.5, 124.9, 60.2, 54.5.

[0092] Example 1

[0093] (1) Ingredients

[0094] By weight, the raw materials for component A include:

[0095] 70 parts of matrix epoxy resin (bisphenol A epoxy resin);

[0096] 15 parts of biphenyl-type phenolic epoxy resin (biphenyl phenolic epoxy resin);

[0097] 185 parts of surface-modified silica (average particle size of 10 μm, modifier R1 is a C4 alkyl alcohol and R2 is a C4 alkyl alcohol);

[0098] Diluent (benzyl glycidyl ether compound: LS-692) 5 parts;

[0099] 5 parts of dispersant (DISPERBYK-110);

[0100] Colorant (carbon black) 2 parts.

[0101] By weight, the raw materials for component B include:

[0102] 85 parts of anhydride curing agent (methyltetrahydrophthalic anhydride);

[0103] 1 part of imidazole accelerator (2-methylimidazole);

[0104] 5 parts of dispersant (DISPERBYK-110);

[0105] 10 parts of anthracene methyl quaternary ammonium salt auxiliaries; the anthracene methyl quaternary ammonium salt auxiliaries of this embodiment have the following structure:

[0106]

[0107] Where R is methyl, R 1 ~R 4 H is a bromide ion, and X is a bromide ion.

[0108] 190 parts of surface-modified silica (average particle size of 10 μm, modifier R1 is a C4 alkyl alcohol and R2 is a C4 alkyl alcohol).

[0109] (2) Preparation and usage methods

[0110] Preparation method of component A:

[0111] The matrix epoxy resin and biphenyl-type phenolic epoxy resin were preheated at 100℃ for 40 min, vacuum stirred for 3 min at a stirring speed of 800 r / min, and then cooled to room temperature. Diluent, dispersant, surface-modified silica and colorant were added, and vacuum stirred for 5 min at a stirring speed of 1000 r / min. The inorganic filler was then ground twice with a three-roll mill to make it more uniformly dispersed. Finally, the mixture was degassed and stirred for 5 min at a stirring speed of 1500 r / min to obtain component A.

[0112] Preparation method of component B:

[0113] Anhydride curing agent, accelerator, dispersant, anthracene methyl quaternary ammonium salt additive, and surface-modified silica were vacuum stirred together for 5 minutes at a stirring speed of 1000 r / min. Then, the mixture was ground in a three-roll mill to make the inorganic filler more evenly dispersed. Finally, the mixture was degassed and stirred for 5 minutes at a stirring speed of 1500 r / min to obtain component B.

[0114] The encapsulation application method of the adhesive in this embodiment:

[0115] Mix component A and component B at a mass ratio of 100:90 until homogeneous, pour the mixture into the motor, degas it, and then heat-cur it: keep it at 100℃ for 2 hours, then at 150℃ for 4 hours, and finally at 180℃ for 2 hours to complete the motor encapsulation.

[0116] Example 2

[0117] (1) Ingredients

[0118] By weight, the raw materials for component A include:

[0119] 65 parts of matrix epoxy resin (bisphenol F epoxy resin);

[0120] 18 parts of biphenyl-type phenolic epoxy resin (tetramethylbiphenyl-type epoxy resin);

[0121] 185 parts of surface-modified silica (average particle size of 5 μm, where R1 of the modifier is a hydroxyl group and R2 is a C2 alkyl alcohol);

[0122] Diluent (benzyl glycidyl ether compound: LS-692) 5 parts;

[0123] 5 parts of dispersant (DISPERBYK-110);

[0124] Colorant (carbon black) 2 parts.

[0125] By weight, the raw materials for component B include:

[0126] 90 parts of anhydride curing agent (methylnadic anhydride);

[0127] 1 part of imidazole accelerator (2-ethyl-4-methylimidazole);

[0128] 5 parts of dispersant (DISPERBYK-110);

[0129] 10 parts of anthracene methyl quaternary ammonium salt auxiliaries; the anthracene methyl quaternary ammonium salt auxiliaries of this embodiment have the following structure:

[0130]

[0131] Where R is ethyl, R' is ethoxy, and R 1 For chlorine, R 2 ~R 4 H is H, and X is fluoroborate.

[0132] 200 parts of surface-modified silica (average particle size of 15 μm, where R1 of the modifier is a hydroxyl group and R2 is a C6 alkyl alcohol).

[0133] (2) Preparation and usage methods

[0134] Preparation method of component A:

[0135] The matrix epoxy resin and biphenyl-type phenolic epoxy resin were preheated at 90°C for 40 min, vacuum stirred for 4 min at a stirring speed of 800 r / min, and then cooled to room temperature. Diluent, dispersant, surface-modified silica and colorant were added, and vacuum stirred for 6 min at a stirring speed of 800 r / min. Then, the mixture was ground twice with a three-roll mill to make the inorganic filler more evenly dispersed. Finally, the mixture was degassed and stirred for 5 min at a stirring speed of 1500 r / min to obtain component A.

[0136] Preparation method of component B:

[0137] Anhydride curing agent, accelerator, dispersant, anthracene methyl quaternary ammonium salt additive, and surface-modified silica were vacuum stirred together for 4 minutes at a stirring speed of 1000 r / min. Then, the mixture was ground in a three-roll mill to make the inorganic filler more evenly dispersed. Finally, the mixture was degassed and stirred for 6 minutes at a stirring speed of 1400 r / min to obtain component B.

[0138] The encapsulation application method of the adhesive in this embodiment:

[0139] Mix component A and component B at a mass ratio of 100:80 until homogeneous, pour the mixture into the motor, degas it, and then heat-cur it: keep it at 100℃ for 2 hours, then at 150℃ for 4 hours, and finally at 180℃ for 2 hours to complete the motor encapsulation.

[0140] Example 3

[0141] (1) Ingredients

[0142] By weight, the raw materials for component A include:

[0143] 75 parts of matrix epoxy resin (bisphenol A / F epoxy resin, mass ratio 1:1)

[0144] 12 parts of biphenyl-type phenolic epoxy resin (biphenyl aryl phenolic resin);

[0145] 195 parts of surface-modified silica (average particle size of 10 μm, where R1 of the modifier is a C10 alkyl alcohol and R2 is a C2 alkyl alcohol);

[0146] Diluent (benzyl glycidyl ether compound: LS-692) 5 parts;

[0147] 5 parts of dispersant (DISPERBYK-110);

[0148] Colorant (titanium dioxide) 2 parts.

[0149] By weight, the raw materials for component B include:

[0150] 85 parts of anhydride curing agent (methyltetrahydrophthalic anhydride);

[0151] 1 part of imidazole accelerator (2-methylimidazole);

[0152] 5 parts of dispersant (DISPERBYK-110);

[0153] Six parts of anthracene methyl quaternary ammonium salt auxiliaries; the anthracene methyl quaternary ammonium salt auxiliaries in this embodiment have the following structure:

[0154]

[0155] Where R is n-hexyl, R' is phenyl, and R 1 It is methyl, R 2 ~R 4 H is H, and X is trifluoromethanesulfonate.

[0156] 200 parts of surface-modified silica (average particle size of 4 μm, modifier R1 is a C10 alkyl alcohol and R2 is a C2 alkyl alcohol).

[0157] (2) Preparation and usage methods

[0158] Preparation method of component A:

[0159] The matrix epoxy resin and biphenyl-type phenolic epoxy resin were preheated at 110℃ for 40 min, vacuum stirred for 3 min at a stirring speed of 900 r / min, and then cooled to room temperature. Diluent, dispersant, surface-modified silica and colorant were added, and vacuum stirred for 5 min at a stirring speed of 900 r / min. The inorganic filler was then dispersed more evenly by grinding twice with a three-roll mill. Finally, the mixture was degassed and stirred for 5 min at a stirring speed of 1600 r / min to obtain component A.

[0160] Preparation method of component B:

[0161] Anhydride curing agent, accelerator, dispersant, anthracene methyl quaternary ammonium salt additive, and surface-modified silica were vacuum-stirred together for 5 minutes at a stirring speed of 900 r / min. Then, the mixture was ground in a three-roll mill to make the inorganic filler more evenly dispersed. Finally, the mixture was degassed and stirred for 5 minutes at a stirring speed of 1600 r / min to obtain component B.

[0162] The encapsulation application method of the adhesive in this embodiment:

[0163] Mix component A and component B at a mass ratio of 100:130 until homogeneous, pour the mixture into the motor, degas it, and then heat-cur it: keep it at 100℃ for 2 hours, then at 150℃ for 4 hours, and finally at 180℃ for 2 hours to complete the motor encapsulation.

[0164] Comparative Example 1

[0165] (1) Ingredients

[0166] This comparative example does not use biphenyl-type phenolic epoxy resin, but uses the same matrix epoxy resin as in Example 1 as a substitute; this comparative example does not use surface-modified silica, but uses silica powder as a substitute.

[0167] Specifically, by mass, the raw materials of component A include:

[0168] 85 parts of matrix epoxy resin (bisphenol A epoxy resin);

[0169] 0 parts of biphenyl-type phenolic epoxy resin;

[0170] 185 parts of silica powder (average particle size 10μm);

[0171] The other raw materials are the same as in Example 1.

[0172] By weight, the raw materials for component B include:

[0173] 190 parts of silica powder (average particle size 10μm);

[0174] The other raw materials are the same as in Example 1.

[0175] (2) Preparation and usage methods

[0176] The preparation methods for components A and B are basically the same as in Example 1, except that the raw materials are replaced according to the formula.

[0177] The encapsulation application method of this comparative adhesive is the same as that in Example 1.

[0178] Comparative Example 2

[0179] (1) Ingredients

[0180] This comparative example does not use anthraquinone quaternary ammonium salt additives.

[0181] Specifically, the raw materials for component A are the same as those in Example 1, and the amount of anthracene methyl quaternary ammonium salt adjuvant in the raw materials for component B is 0; the proportions of other raw materials are the same as those in Example 1.

[0182] (2) Preparation and usage methods

[0183] The preparation method of component A is the same as in Example 1.

[0184] The preparation method of component B is the same as that in Example 1, except that anthracene methyl quaternary ammonium salt is not added. The other processes are the same as in Example 1.

[0185] The encapsulation application method of this comparative adhesive is the same as that in Example 1.

[0186] Comparative Example 3

[0187] (1) Ingredients

[0188] In this comparative example, the proportion of biphenyl-type phenolic epoxy resin is 25 parts, and the proportion of matrix epoxy resin is 60 parts. Specifically, by weight, the raw materials of component A include:

[0189] 60 parts of matrix epoxy resin (bisphenol A epoxy resin);

[0190] 25 parts of biphenyl-type phenolic epoxy resin (biphenyl phenolic epoxy resin);

[0191] Other raw materials are the same as in Example 1;

[0192] The raw materials for component B are the same as those in Example 1.

[0193] (2) Preparation and usage methods

[0194] The preparation methods for components A and B are the same as in Example 1.

[0195] The encapsulation application method of this comparative adhesive is the same as that in Example 1.

[0196] Detection and Analysis

[0197] Performance tests were conducted on various indicators of the one-component epoxy underfill adhesives used in the embodiments and comparative examples, as well as similar epoxy adhesive products available on the market. The test methods are as follows:

[0198] 1. Glass transition temperature (T) g Test method: DSC;

[0199] 2. Flame retardant rating, UL 94 "Test methods for flammability of plastic materials";

[0200] 3. Tensile strength and elongation at break, GB / T 2567-2008 "Test methods for properties of resin castings".

[0201] The test results are shown in Table 1.

[0202] Table 1 Performance test results of each embodiment and comparative example

[0203]

[0204] As can be seen from the test results in Table 1, the adhesives in each embodiment have high flame retardancy ratings while also exhibiting good toughness. In Comparative Example 1, the absence of biphenyl-type phenolic epoxy resin prevents the formation of a supramolecular ordered structure, resulting in a significant decrease in heat resistance and intrinsic thermal conductivity, and a substantial reduction in the synergistic flame retardant effect. The unmodified silica used is prone to agglomeration, exhibiting poor interfacial bonding with the resin, leading to low tensile strength and insufficient toughness. Consequently, the adhesive is prone to brittleness and detachment after encapsulation.

[0205] Comparative Example 2 does not use anthracene methyl quaternary ammonium salt additives, so it cannot form a synergistic flame retardant effect with biphenyl-type phenolic epoxy resin. Relying solely on the flame retardant properties of the biphenyl-type phenolic epoxy resin itself, it cannot meet the requirements for motor packaging. Furthermore, without the catalytic char formation and non-flammable gas release effect of anthracene methyl quaternary ammonium salt additives, the amount of char formed during combustion is small, and the fire spreads rapidly.

[0206] In Comparative Example 3, the excessive amount of biphenyl-type phenolic epoxy resin resulted in overly rigid molecular chains, leading to a sharp decrease in adhesive toughness and easy cracking after curing. Furthermore, the excessive amount of biphenyl-type phenolic epoxy resin reduced the system's compatibility, causing delamination and affecting the stability of bonding strength and flame retardant properties.

Claims

1. A two-component synergistic flame-retardant modified toughened epoxy adhesive, characterized in that, It is divided into component A and component B. When using it, mix component A and component B at a mass ratio of 100:80~150 and heat to cure. By weight, the raw materials of component A include: 65-75 parts of matrix epoxy resin, 10-25 parts of biphenyl phenolic epoxy resin, and 150-250 parts of surface-modified silica. By weight, the raw materials of component B include: 70-100 parts of acid anhydride curing agent, 150-250 parts of surface-modified silica, and 1-15 parts of anthracene methyl quaternary ammonium salt additive; The anthracene methyl quaternary ammonium salt adjuvant includes: , At least one of the following; wherein: R is selected from C1~C12 alkyl groups; R' is selected from H, C1~C12 alkyl, C1~C12 alkoxy, substituted aryl, unsubstituted aryl, substituted aryloxy, and unsubstituted aryloxy. R 1 ~R 4 Each is independently selected from H, halogen, and methyl; X is selected from halogens, nitrates, acetates, sulfates, trifluoromethanesulfonates, fluoroborates, and fluoroantimonates; The modifier for the surface-modified silica is... R1 and R2 are each independently selected from hydroxyl groups or C1-C12 alkyl alcohols.

2. The two-component synergistic flame-retardant modified and toughened epoxy adhesive according to claim 1, characterized in that, The matrix epoxy resin is a polyepoxy functional group glycidyl ether epoxy resin; the matrix epoxy resin includes one or more of bisphenol A, bisphenol F, bisphenol S, and phenolic epoxy resin. The biphenyl-type phenolic epoxy resin includes one or more of tetramethylbiphenyl diphenol type epoxy resin, biphenyl phenol type epoxy resin, and biphenyl aryl phenolic resin.

3. The two-component synergistic flame-retardant modified and toughened epoxy adhesive according to claim 1, characterized in that, The anhydride curing agent is selected from one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride.

4. The two-component synergistic flame-retardant modified and toughened epoxy adhesive according to claim 1, characterized in that, The particle size of the surface-modified silica is 1μm~15μm.

5. The two-component synergistic flame-retardant modified and toughened epoxy adhesive according to claim 1, characterized in that, The method for preparing the surface-modified silica includes: Silica with physically adsorbed water removed from its surface is mixed with anhydrous toluene containing 1 wt% to 5 wt% modifier under an inert atmosphere to form a hydrogen-bonded complex pre-adsorption system. Then, under an inert atmosphere, at a temperature of 140℃ to 180℃ and a pressure of 2 MPa to 4 MPa, the mixture is stirred for 3 to 6 hours to obtain surface-modified silica.

6. The two-component synergistic flame-retardant modified toughened epoxy adhesive according to any one of claims 1 to 5, characterized in that, The raw materials of component A also include 0-10 parts of dispersant, 0-5 parts of colorant, and 0-10 parts of diluent; the raw materials of component B also include 0-2 parts of accelerator and 0-10 parts of dispersant.

7. The two-component synergistic flame-retardant modified toughened epoxy adhesive according to claim 6, characterized in that: The diluent is a phenyl glycidyl ether and / or an allyl glycidyl ether compound; The dispersant is a non-solvent-based high molecular weight wetting and dispersing agent; Colorants include one or more of carbon black, titanium dioxide, and iron oxide red; The accelerator is an imidazole accelerator.

8. The method for preparing the two-component synergistic flame-retardant modified and toughened epoxy adhesive according to any one of claims 1 to 7, characterized in that, Component A and Component B are prepared by uniformly mixing their respective raw materials.

9. The preparation method of the two-component synergistic flame-retardant modified toughened epoxy adhesive according to claim 8, characterized in that, In the preparation of component A, the matrix epoxy resin and biphenyl-type phenolic epoxy resin are preheated to 80℃~120℃ before mixing, and the mixing of the remaining raw materials is carried out below 80℃; in the preparation of component B, the raw materials are mixed below 80℃.

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