Bromine-nitrogen synergistic flame-retardant modified epoxy resin as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of epoxy resin, and particularly relates to bromine-nitrogen synergistic flame-retardant modified epoxy resin as well as a preparation method and application thereof. First epoxy resin, tetrabromobisphenol A and a catalyst are subjected to bulk polymerization, obtained tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate are subjected to a modification reaction, obtained initial modified resin, high-bromine epoxy resin and second epoxy resin are mixed, and the bromine-nitrogen synergistic flame-retardant modified epoxy resin is obtained. According to the invention, the tetrabromobisphenol A modified epoxy resin is subjected to secondary modification, so that the flame-retardant effect can be effectively obtained, residues of tetrabromobisphenol A are further effectively avoided, redundant hydroxyl groups of tetrabromobisphenol A can be consumed by isocyanate in MDI, and a bromine-nitrogen synergistic flame-retardant effect is formed; through effective cooperation of the low-molecular-weight resin and the high-molecular-weight resin, after curing, molecular chains form an interpenetrating network structure, and it can be ensured that after curing, the crosslinking density is stable, and heat resistance and toughness are both considered.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy resins, and specifically relates to a bromine-nitrogen synergistic flame-retardant modified epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin (EP) is widely used in various industrial fields due to its excellent physical and chemical properties, such as coatings, laminates, adhesives, circuit boards, aerospace and other electronic industries. However, like most organic polymer resins, epoxy resin is a flammable substance, which limits its application in fields with high flame retardancy requirements; at the same time, ordinary epoxy resin also has problems such as poor heat resistance, insufficient toughness, and poor impact resistance. In order to give full play to the excellent properties of epoxy resin and make up for its own shortcomings, it is necessary to modify epoxy resin in a targeted manner to improve its toughness and heat resistance.

[0003] The related technology further discloses an epoxy resin composition and a preparation method thereof, which is mainly prepared by reacting an epoxy resin with tetrabromobisphenol A and then diluting it. This method can obtain an epoxy resin with a glass transition temperature of about 140°C, but its toughness is poor, especially when used in winter, it is easy to cause warping or stress whitening of the board. Summary of the invention

[0004] The purpose of the present invention is to provide a bromine-nitrogen synergistic flame-retardant modified epoxy resin and a preparation method and application thereof. The bromine-nitrogen synergistic flame-retardant modified epoxy resin provided by the present invention has excellent flame retardant properties, and at the same time, after curing, the cross-linking density is stable, and it has good heat resistance and plasticity, and good impact resistance.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a bromine-nitrogen synergistic flame-retardant modified epoxy resin, comprising the following steps:

[0007] The first epoxy resin, tetrabromobisphenol A and a catalyst are subjected to bulk polymerization to obtain tetrabromobisphenol A epoxy resin;

[0008] The tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate are subjected to a modification reaction to obtain an initial modified resin;

[0009] The initial modified resin, high-bromine epoxy resin and second epoxy resin are mixed to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin, wherein the mass content of bromine element in the high-bromine epoxy resin is ≥46%.

[0010] Preferably, the mixing further comprises:

[0011] The modified mixed system obtained by mixing is diluted with an organic solvent to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin.

[0012] Preferably, the first epoxy resin comprises one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and hydrogenated bisphenol A epoxy resin;

[0013] The purity of tetrabromobisphenol A is ≥99.9%, the acetone color is ≤35APHA, and the free phenol content is ≤15ppm;

[0014] The mass ratio of the first epoxy resin to the tetrabromobisphenol A is (30-40):(9-10).

[0015] Preferably, the catalyst comprises one or more of tetrabutylammonium bromide, triphenylphosphine, tetramethylammonium chloride and butyltriphenylphosphine bromide;

[0016] The mass ratio of the first epoxy resin to the catalyst is (30-40): (0.01-0.03);

[0017] The heat preservation temperature of the bulk polymerization is 160-170° C., and the heat preservation time is 100-150 minutes.

[0018] Preferably, the diphenylmethane diisocyanate includes one or more of MDI50, MDI100 and MDI1102;

[0019] The mass ratio of the first epoxy resin to the diphenylmethane diisocyanate is (30-40): (7-8);

[0020] The insulation temperature of the modification reaction is 170-175° C., and the insulation time is 30-90 minutes.

[0021] Preferably, the mass content of bromine in the high-bromine epoxy resin is 46-48%, the epoxy equivalent is 390-410 g / eq, and the hydrolyzable chlorine is ≤500 ppm;

[0022] The mass ratio of the first epoxy resin to the high-bromine epoxy resin is (30-40): (15-20);

[0023] The mass ratio of the first epoxy resin to the second epoxy resin is (30-40):(4-6);

[0024] The mixing heat preservation temperature is 165-170° C., and the heat preservation time is 30-60 minutes.

[0025] Preferably, the organic solvent comprises one or more of butanone, propylene glycol methyl ether, acetone and n-butanol;

[0026] The mass ratio of the first epoxy resin to the organic solvent is (30-40):(20-30).

[0027] The present invention provides a bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared by the preparation method described in the above technical scheme.

[0028] The present invention provides the use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin described in the above technical solution in a flame-retardant laminate or a printed circuit board.

[0029] The present invention provides the use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin described in the above technical solution in household appliances, electronic computers, mobile phones or transportation vehicles.

[0030] The invention provides a preparation method of a bromine-nitrogen synergistic flame-retardant modified epoxy resin, comprising the following steps: subjecting a first epoxy resin, tetrabromobisphenol A and a catalyst to bulk polymerization to obtain a tetrabromobisphenol A epoxy resin; subjecting the tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate to a modification reaction to obtain an initial modified resin; and mixing the initial modified resin, a high-bromine epoxy resin and a second epoxy resin to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin, wherein the mass content of bromine element in the high-bromine epoxy resin is greater than or equal to 46%. The present invention firstly reacts tetrabromobisphenol A with epoxy resin, introduces tetrabromobisphenol A into the epoxy resin structure through bulk polymerization, performs a first modification on the epoxy resin, and obtains the tetrabromobisphenol A epoxy resin with flame retardant performance; then the obtained tetrabromobisphenol A epoxy resin reacts with diphenylmethane diisocyanate (MDI), and performs a second modification on the epoxy resin. The present invention can achieve the following effects through the second modification: first, the unreacted tetrabromobisphenol A in the first modification and the excess hydroxyl group of tetrabromobisphenol A in the tetrabromobisphenol A epoxy resin can be consumed by the isocyanate group in MDI, and the residue of tetrabromobisphenol A can be effectively avoided (if small molecules of tetrabromobisphenol A remain, It will cause bubbles to appear during the subsequent board making or reflow soldering, or the pressing of the board will cause board flowers), but it will not affect the excellent performance of the epoxy resin itself; second: through the reaction with MDI, oxazolidinone and other groups are introduced into the main chain of tetrabromobisphenol A epoxy resin (generated by the reaction of isocyanate in MDI with epoxy group). Since the MDI structure contains a large number of rigid structures such as five-membered oxazolidinone, six-membered isocyanate acetate ring and benzene ring, the heat resistance of the cured resin after the second modification can be improved; at the same time, the oxazolidinone group is introduced into the main chain, the molecular chain is extended, and the toughness is increased; third: through the second modification, the nitrogen element in MDI is introduced into the resin to form a bromine-nitrogen synergistic flame retardant effect. Finally, the present invention mixes the resin after the second modification with the high-bromine epoxy resin and the second epoxy resin, and effectively cooperates the low molecular weight resin (the second epoxy resin and the high-bromine epoxy resin) with the high molecular weight resin (that is, the initial modified resin obtained after the second modification), so that the molecular chains form an interpenetrating network structure after curing, which can ensure the stability of the crosslinking density of the modified resin after curing, and has good heat resistance and toughness; and can further adjust the bromine content and molecular weight of the initial modified resin, improve the operating space during industrial operation, thereby achieving an overall optimization effect, and obtaining a bromine-nitrogen synergistic flame-retardant modified epoxy resin product. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the schematic diagram of bulk polymerization;

[0032] Figure 2 This is the reaction principle diagram of functional groups when MDI reacts with epoxy resin;

[0033] Figure 3This is the reaction principle diagram of the reaction between MDI and tetrabromobisphenol A. DETAILED DESCRIPTION

[0034] The present invention provides a method for preparing a bromine-nitrogen synergistic flame-retardant modified epoxy resin, comprising the following steps:

[0035] The first epoxy resin, tetrabromobisphenol A and a catalyst are subjected to bulk polymerization to obtain tetrabromobisphenol A epoxy resin;

[0036] The tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate are subjected to a modification reaction to obtain an initial modified resin;

[0037] The initial modified resin, high-bromine epoxy resin and second epoxy resin are mixed to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin, wherein the mass content of bromine element in the high-bromine epoxy resin is ≥46%.

[0038] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0039] The present invention carries out bulk polymerization on a first epoxy resin, tetrabromobisphenol A and a catalyst to obtain tetrabromobisphenol A epoxy resin.

[0040] In the present invention, the principle diagram of bulk polymerization is as follows Figure 1 As shown below, combined Figure 1, the preparation process of tetrabromobisphenol A epoxy resin in the present invention is described in detail. In the present invention, the bulk polymerization is carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen or an inert gas, and is specifically nitrogen in the embodiment. The first epoxy resin preferably includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and hydrogenated bisphenol A epoxy resin. In a specific embodiment of the present invention, the first epoxy resin is an epoxy resin produced by Yangnong Jinhu, and the first epoxy resin is produced based on bio-based glycerol as a supporting raw material, which is a bio-based epoxy resin. The various properties of the bio-based epoxy resin reach or exceed those of petroleum-based products, and have significant advantages in terms of resource renewability, carbon emissions, environmental compatibility, and molecular structure characteristics. In the present invention, the purity of the tetrabromobisphenol A is preferably ≥99.9%, the acetone color is preferably ≤35APHA, and the free phenol content is preferably ≤15ppm. The catalyst preferably includes one or more of tetrabutylammonium bromide, triphenylphosphine, tetramethylammonium chloride and butyltriphenylphosphine bromide. The mass ratio of the first epoxy resin and the tetrabromobisphenol A is preferably (30-40): (9-10), more preferably (32-38): (9-9.6), and further preferably (33-35): (9.1-9.3). In the present invention, the present invention preferably controls the mass ratio of the first epoxy resin and the tetrabromobisphenol A within the above range. If it is not within the above range, too high a bromine content will affect the toughness, CAF index and voltage resistance of the board after final curing; too low a bromine content will affect the flame retardant properties of the finished product and cannot meet the flame retardant requirements of FR-4. The mass ratio of the first epoxy resin and the catalyst is preferably (30-40): (0.01-0.03), more preferably (32-38): 0.02.

[0041] In the present invention, the bulk polymerization of the first epoxy resin, tetrabromobisphenol A and the catalyst preferably includes the following steps: pre-mixing the first epoxy resin and tetrabromobisphenol A, heating them to a first temperature, mixing them with the catalyst and heating them to the temperature of the bulk polymerization for a second time, and performing the bulk polymerization. The heating rate of the second heating is preferably 1°C / min. The first temperature is preferably 110-120°C, and specifically 112°C in the embodiment. The insulation temperature of the bulk polymerization is preferably 160-170°C, and specifically 165°C in the embodiment; the insulation time is preferably 100-150min, and specifically 130min in the embodiment. In the present invention, the bulk polymerization is carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen or an inert gas, and specifically nitrogen in the embodiment.

[0042] After obtaining tetrabromobisphenol A epoxy resin, the present invention performs a modification reaction on the tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate to obtain an initial modified resin. In the present invention, during the modification reaction, the functional groups of MDI and epoxy resin react in the following manner: Figure 2 As shown; at the same time, MDI reacts with the unreacted tetrabromobisphenol A in the first modification. The reaction principle is as follows Figure 3 As shown, Figure 3 This means that both terminal hydroxyl groups of tetrabromobisphenol A need to react completely. Since tetrabromobisphenol A in the system has theoretically reacted completely, the reaction between MDI and tetrabromobisphenol A generally does not occur. However, if there is residual tetrabromobisphenol A in the system, the reaction between MDI and tetrabromobisphenol A will occur to eliminate free tetrabromobisphenol A.

[0043] In the present invention, the modification reaction is preferably carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen or an inert gas, specifically nitrogen in the embodiment. The diphenylmethane diisocyanate preferably includes one or more of MDI50, MDI100 and MDI1102. The mass ratio of the first epoxy resin and the diphenylmethane diisocyanate is preferably (30-40): (7-8), more preferably (32-38): (7.2-7.8), and further preferably (33-35): (7.5-7.7). In the present invention, the present invention preferably controls the mass ratio of the first epoxy resin and the diphenylmethane diisocyanate within the above range, and improves the stability of the final product by controlling the nitrogen content, but the amount of diphenylmethane diisocyanate used cannot be too high. If the reaction is too high, gelation will occur, which is not conducive to the reaction.

[0044] The present invention mixes the tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate for modification reaction. In the present invention, the mixing of the tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate preferably includes the following steps: cooling the tetrabromobisphenol A epoxy resin obtained by bulk polymerization to a second temperature, while dripping the MDI, heating it to the insulation temperature of the modification reaction, and after the MDI is dripped, timing the insulation modification reaction. The second temperature is preferably 100-110°C, specifically 102°C in the embodiment. The insulation temperature of the modification reaction is preferably 170-175°C, and the insulation time is preferably 30-90min. In the present invention, the time for dripping the MDI is preferably 60-80min.

[0045] After obtaining the initial modified resin, the present invention mixes the initial modified resin, high-bromine epoxy resin and second epoxy resin to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin, wherein the mass content of bromine element in the high-bromine epoxy resin is ≥46%.

[0046] In the present invention, the mixing of the initial modified resin, the high-bromine epoxy resin and the second epoxy resin is preferably carried out in a protective gas atmosphere, and the protective gas is preferably nitrogen or an inert gas, and specifically nitrogen in the embodiment. The mass content of bromine in the high-bromine epoxy resin is preferably 46-48%, the epoxy equivalent is preferably 390-410 g / eq, and the hydrolyzable chlorine is preferably ≤500 ppm. In a specific embodiment of the present invention, the high-bromine epoxy resin is preferably a high-bromine 400 epoxy resin purchased from Nantong Xingchen Synthetic Materials Co., Ltd.

[0047] In the present invention, the second epoxy resin preferably includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and hydrogenated bisphenol A epoxy resin. In a specific embodiment of the present invention, the second epoxy resin is an epoxy resin produced by Yangnong Jinhu, and the second epoxy resin is produced based on bio-based glycerol as a supporting raw material, and is a bio-based epoxy resin. The various properties of bio-based epoxy resins reach or exceed those of petroleum-based products, and have significant advantages in resource renewability, carbon emissions, environmental compatibility, and molecular structure characteristics. In a specific embodiment of the present invention, the type of the second epoxy resin is preferably the same as the type of the first epoxy resin. The mass ratio of the first epoxy resin to the high-bromine epoxy resin is preferably (30-40): (15-20), more preferably (32-38): (16-19), and further preferably (33-35): (17.5-18.5). The mass ratio of the first epoxy resin to the second epoxy resin is preferably (30-40): (4-6), more preferably (32-38): (4.3-5.6), further preferably (33-35): (4.7-5.2), and most preferably (33-35): 5. The mixing insulation temperature is 165-170°C, and the insulation time is preferably 30-60 minutes. The present invention can control the bromine content of the final product by controlling the mass ratio of the first epoxy resin to the second epoxy resin, ensuring that the flame retardancy after curing can meet the V-0 grade requirement of UL-94; at the same time, the viscosity of the final product is controlled, while taking into account that the tg value of the finished product can be maintained above 140°C.

[0048] After the initial modified resin, the high-bromine epoxy resin and the second epoxy resin are mixed, the present invention preferably further comprises: diluting the modified mixed system obtained by mixing with an organic solvent to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin.

[0049] In the present invention, the organic solvent preferably includes one or more of butanone, propylene glycol methyl ether, acetone and n-butanol. The mass ratio of the first epoxy resin to the organic solvent is preferably (30-40): (20-30), more preferably (32-38): (21-28), further preferably (33-35): (23-26), and most preferably (33-35): 25. The dilution is performed under stirring.

[0050] The present invention provides a bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared by the preparation method described in the above technical scheme. In the present invention, the bromine content of the bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared by the present invention is 18-21%, the nitrogen content is 3-7%, and the average molecular weight of the bromine-nitrogen synergistic flame-retardant modified epoxy resin product is ≥1000.

[0051] The present invention provides the use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin described in the above technical solution in a flame-retardant laminate or a printed circuit board.

[0052] In the present invention, the main component of the flame retardant laminate is bromine nitrogen synergistic flame retardant modified epoxy resin, and does not contain copper cladding. The printed circuit substrate is a plate that has been processed after copper cladding.

[0053] The present invention provides the use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin described in the above technical solution in household appliances, electronic computers, mobile phones or transportation vehicles.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The present invention performs secondary modification on the epoxy resin modified with the flame retardant (tetrabromobisphenol A), thereby effectively obtaining the flame retardant effect and further effectively avoiding the residue of tetrabromobisphenol A. The excess hydroxyl groups of tetrabromobisphenol A will be consumed by the isocyanate groups in MDI, and a bromine-nitrogen synergistic flame retardant effect will be formed.

[0056] (2) The present invention effectively combines low molecular weight resin with high molecular weight resin, and the molecular chains form an interpenetrating network structure after curing, which can ensure the stability of the cross-linking density after curing, and take into account both heat resistance and toughness;

[0057] (3) The present invention is the first to apply bio-based epoxy resin to explore the field of electronics and electrical engineering, and promote the transformation and upgrading of the epoxy resin industry under the background of dual carbon.

[0058] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0059] The epoxy resin used in the following examples is an epoxy resin produced by Yangnong Jinhu. The epoxy resin used in the examples is produced based on bio-based glycerol as a supporting raw material and is a bio-based epoxy resin.

[0060] Example 1

[0061] Under nitrogen protection, 347.9 g of bisphenol A epoxy resin and 91.8 g of tetrabromobisphenol A were added into the reactor, mixed evenly, heated to 112°C, 0.2 g of butyl triphenylphosphine bromide was added, the temperature was slowly increased (1°C / min) to 165°C, the timing was started and the temperature was kept for 130 min, then the temperature was lowered to 102°C, 76.5 g of MDI 100 was added dropwise, and the temperature was slowly increased (60 min for the addition to be completed), and the temperature was controlled when the temperature reached 170°C, and the temperature was maintained between 170 and 175°C. After the addition of MDI 100 was completed, the temperature was kept for 30 min. After the insulation was completed, 183.6 g of high-bromine epoxy resin and 50 g of bisphenol A epoxy resin were added, and the temperature was kept at 165-170°C for 30 min, the nitrogen was stopped, and finally 250 g of butanone was slowly added after the temperature was lowered, and after stirring evenly, the temperature was lowered and the material was discharged to obtain a bromine-nitrogen synergistic flame-retardant modified epoxy resin. The characterization parameters are tested and laminate board making tests are carried out at the same time.

[0062] Example 2

[0063] Under nitrogen protection, 347.9 g of bisphenol F epoxy resin and 91.8 g of tetrabromobisphenol A were added into the reactor, mixed evenly, heated to 112°C, 0.2 g of tetramethylammonium chloride was added, the temperature was slowly increased (1°C / min) to 165°C, and insulation was started for 130 min, then cooled to 102°C, 76.5 g of MDI 100 was added dropwise, and the temperature was slowly added dropwise (addition was completed within 60 min) to increase the temperature. When the temperature reached 170°C, temperature control was started and the temperature was maintained between 170 and 175°C. After the addition of MDI 100 was completed, insulation was performed for 30 min. After the insulation was completed, 183.6 g of high-bromine epoxy resin and 50 g of bisphenol A epoxy resin were added, and insulation was performed at 165 to 170°C for 30 min. The nitrogen was stopped, and 250 g of butanone was slowly added after cooling. After stirring evenly, the temperature was reduced and the material was discharged to obtain a bromine-nitrogen synergistic flame-retardant modified epoxy resin. The characterization parameters are tested and laminate board making tests are carried out at the same time.

[0064] Example 3

[0065] Under nitrogen protection, 347.9g of bisphenol A epoxy resin and 91.8g of tetrabromobisphenol A were added into the reactor, mixed evenly, heated to 112°C, 0.2g of butyl triphenylphosphine bromide was added, the temperature was slowly raised (1°C / min) to 165°C, and insulation was started for 130min, then cooled to 102°C, 76.5g of MDI200 was added dropwise, and the temperature was slowly added dropwise (addition was completed within 60min) to raise the temperature. When the temperature reached 170°C, temperature control was started and the temperature was maintained between 170 and 175°C. After the addition of MDI200 was completed, insulation was performed for 30min. After the insulation was completed, 183.6g of high-bromine epoxy resin and 50g of bisphenol A epoxy resin were added, and insulation was performed at 165-170°C for 30min. The nitrogen was stopped, and 250g of butanone was slowly added after cooling. After stirring evenly, the temperature was cooled and discharged to obtain a bromine-nitrogen synergistic flame-retardant modified epoxy resin. The characterization parameters are tested and laminate board making tests are carried out at the same time.

[0066] Example 4

[0067] Under nitrogen protection, 347.9g of bisphenol A epoxy resin and 91.8g of tetrabromobisphenol A were added into the reactor, mixed evenly, heated to 112°C, 0.2g of butyl triphenylphosphine bromide was added, the temperature was slowly raised (1°C / min) to 165°C, and insulation was started for 130min, then cooled to 102°C, 10076.5g of MDI was added dropwise, and the temperature was slowly added dropwise (60min of addition was completed) to increase the temperature. When the temperature reached 170°C, temperature control was started and the temperature was maintained between 170 and 175°C. After the addition of MDI was completed, insulation was carried out for 30min. After the insulation was completed, 183.6g of high-bromine epoxy resin and 50g of bisphenol A epoxy resin were added, and insulation was carried out at 165-170°C for 30min. The nitrogen was stopped, and 250g of propylene glycol methyl ether was slowly added after cooling. After stirring evenly, the temperature was reduced and the material was discharged to obtain a bromine-nitrogen synergistic flame-retardant modified epoxy resin. The characterization parameters are tested and laminate board making tests are carried out at the same time.

[0068] Test Example 1

[0069] The test results of the physical and chemical properties of the bromine-nitrogen synergistic flame-retardant modified epoxy resins prepared in Examples 1 to 4 are shown in Table 1.

[0070] Table 1 Test results of physical and chemical properties of bromine-nitrogen synergistic flame-retardant modified epoxy resins prepared in Examples 1 to 4

[0071] Test items Example 1 Example 2 Example 3 Example 4 Conventional brominated resin Epoxy equivalent g / eq 445.1 428 469 445 420～445 Viscosity cp.s 1056 1152 1958 1319 Max2000 Solid content% 74.9 75.2 74.6 75.2 79～81 Chroma G 9 9 9 9 11～13 Appearance Brown transparent Brown transparent Brown transparent Brown transparent Dark brown transparent Bromine content% 18.7 18.9 18.7 18.8 18.5～21.5

[0072] The conventional bromide resin in Table 1 is brominated epoxy resin GEBR555A75 produced by "Hongchang Electronic Materials Co., Ltd."

[0073] The test results in Table 1 show that:

[0074] 1. The bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared in Examples 1 to 4 reacted completely, and the finished product was brown and transparent, indicating that the isocyanate in MDI had reacted with the epoxy resin, and the finished product could meet the customer's requirements for appearance;

[0075] 2. Among the bromine-nitrogen synergistic flame-retardant modified epoxy resins prepared in Examples 1 to 4, the bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared in Example 2 has a slightly lower epoxy equivalent because bisphenol F epoxy resin participates in the reaction; in the bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared in Example 3, the MDI monomer is switched to polymerized MDI, and the polymerized MDI is connected to the body, thereby increasing the molecular weight, reducing the epoxy value, and increasing the epoxy equivalent accordingly;

[0076] 3. The bromine-nitrogen synergistic flame-retardant modified epoxy resins prepared in Examples 1 to 4 can meet the conventional requirements for bromine content, and the bromine-nitrogen synergistic flame-retardant effect is more advantageous than conventional brominated epoxy resins.

[0077] Test Example 2

[0078] Application Assessment Test:

[0079] The bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared in Examples 1 to 4 was tested for laminate board making, and dicyandiamide was used as a curing agent and 2-methylimidazole as an accelerator for glue adjustment. The semi-cured sheet was made, the board was pressed, and the board was analyzed according to the laminate process.

[0080] The laminate is made as follows:

[0081] 1. The preparation of the glue solution for the laminate is shown in Table 2. The reference substance in Table 2 is the brominated epoxy resin GEBR555A75 produced by "Hongchang Electronic Materials Co., Ltd.". The solvent in Table 2 is N, N-dimethylformamide (DMF) or propylene glycol methyl ether (PM). The GT test results in Table 2 are the gel time test results of the glue solution for the laminate.

[0082] Table 2 Glue formula for laminated board

[0083] name Example 1 Example 2 Example 3 Example 4 Control group Finished resin (g) 125 125 125 125 125 Dicyandiamide(g) 2.5 2.5 2.5 2.5 2.5 2-Methylimidazole(g) 0.12 0.12 0.12 0.12 0.12 Solvents Moderate Moderate Moderate Moderate Moderate Solid content (%) 62 62 62 62 62 GT(S) 203 206 212 207 211

[0084] 2. Production of prepreg sheets

[0085] 2.1 Cutting of fiberglass cloth

[0086] Cut the standard 7628 fiberglass cloth into 30×30cm size and quantity.

[0087] 2.2 Prepreg production

[0088] Weigh the glue (25g glue + 7g acetone), apply it evenly on both sides of the fiberglass cloth with a brush, clamp the glued fiberglass cloth with a clamp, hang it on the hot air oven, and start baking.

[0089] Baking conditions: 175℃, 4min

[0090] 2.3 Prepreg GT test (prepreg powder test results after baking)

[0091] Rub the semi-cured sheet and rub the glue attached to the glass fiber cloth into powder, and sift it with a 140-mesh sieve. Weigh 0.3g of the sieved powder and test the semi-curing time to be between 100-120 seconds.

[0092] 3. Pressing plate. Cut the semi-cured sheets that meet the requirements into 30×30cm. Press according to the pressing plate conditions. The pressing plate conditions are shown in Table 3. In Table 3, steps 1 to 5 are a process of gradually heating up and gradually pressurizing. Control the heating and pressurizing rate. Too fast will affect the quality of the pressed sheet and easily cause glue flow. Step 6 is temperature-controlled pressing, which is a key aging and pressure-maintaining process. Table 4 shows the results of the laminate board making test. The test method for bending strength in Table 4 is: GB / T41049-2021. The reference product in Table 4 is a laminate prepared by the above method using the brominated epoxy resin GEBR555A75 produced by "Hongchang Electronic Materials Co., Ltd."

[0093] Table 3 Pressing plate conditions

[0094] step 1 2 3 4 5 6 <![CDATA[Pressure kg / cm 2 > 16 16 25 28 30 35 Temperature ℃ 50 85 115 120 160 175 Time min 5 15 15 10 15 50

[0095] Table 4 Test results of laminated board made from resin products prepared in Examples 1 to 4

[0096]

[0097]

[0098] The characterization results in Table 4 show that the heat resistance of the resin product is mainly reflected in the tg value. The tg value of the example product in Table 4 is higher than that of the reference product, which can indicate that the resin provided by the present invention has good heat resistance when used to make laminated boards. At the same time, it exhibits good punching processability and good bending strength performance, and it can be confirmed that the products prepared in Example 1 and Example 4 exhibit good plasticity. Compared with other examples and reference examples, they are inferior.

[0099] In Table 4, Example 2 uses bisphenol F epoxy resin for synthesis. Bisphenol F epoxy resin has two methyl groups missing in each molecular chain in terms of structure, and has better intermolecular flexibility, and the product exhibits better flexibility. Relatively speaking, the crosslinking density will be lower than that of bisphenol A epoxy resin in other examples, and its tg value will be lower.

[0100] In summary, we can draw the following conclusions:

[0101] 1. The resin products of Examples 1 to 4 are compared with the reference product. The resin products of Examples 1 to 4 use bromine-nitrogen synergistic flame retardant to replace conventional bromine-based flame retardant, and the flame retardant performance has room for improvement. At present, the brominated resins on the market need to increase the bromine content to more than 19.5% to meet the flame retardant requirements to provide cost space for downstream customers. When using resins with a bromine content exceeding 19.5%, customers can add fillers to the glue to reduce costs, while also taking into account the flame retardant effect;

[0102] 2. Comparing Example 1 with Example 2, Example 1 has better performance in bending strength and good performance in punching processability. It can be confirmed that the modified bisphenol A epoxy resin is more applicable than the bisphenol F epoxy resin in the laminate.

[0103] 3. Compared with other embodiments, Example 3 has a large difference in water absorption, which is mainly due to the choice of catalyst. After the reaction, tetramethylammonium chloride will remain in the system. This catalyst has strong water absorption, which will affect the performance of the board in later application performance.

[0104] 4. The different solvents in Example 4 and Example 1 have little effect on the application performance of the product. The substrate does not have defects such as edge bursting, delamination, and bagging during the punching process, and the punching performance and punching quality are good. Secondly, after the substrate is V-cut, there will be no breakage or fracture during transportation.

[0105] Example 5

[0106] Under nitrogen protection, 347.9 g of bisphenol A epoxy resin and 91.8 g of tetrabromobisphenol A were added into the reactor, mixed evenly, heated to 112°C, 0.2 g of butyl triphenylphosphine bromide was added, the temperature was slowly increased (1°C / min) to 165°C, the timing was started and the temperature was kept for 130 min, then the temperature was lowered to 102°C, 76.5 g of MDI 100 was added dropwise, and the temperature was slowly increased (60 min for the addition to be completed), and the temperature was controlled when the temperature reached 170°C, and the temperature was maintained between 170 and 175°C. After the addition of MDI 100 was completed, the temperature was kept for 30 min. After the insulation was completed, 136.3 g of high-bromine epoxy resin and 100 g of bisphenol A epoxy resin were added, and the temperature was kept at 165-170°C for 30 min, the nitrogen was stopped, and 250 g of butanone was slowly added after the temperature was lowered. After stirring evenly, the temperature was lowered and the material was discharged to obtain a bromine-nitrogen synergistic flame-retardant modified epoxy resin. The characterization parameters were tested and the laminate board making test was carried out according to the above method.

[0107] Test results: epoxy equivalent 413.8g / eq, viscosity 982.6cp.s, solid content 75%, bromine content 16.8%, color 9G.

[0108] The flame retardancy of the board tested is V-1, the tg value is 140.7℃, and the bending strength has also decreased significantly. The warp is 268 and the weft is 219, which cannot meet the requirements of FR-4 board.

[0109] From the above embodiments, it can be seen that the present invention provides an epoxy resin with flame retardant function, and has a relatively excellent performance in electronic circuits, and the cost is not high, and it can form competitiveness in the market; the present invention adopts synergistic flame retardant than single flame retardant, and the use of single flame retardant bromine can improve flame retardancy, and excessive bromine content will affect the mechanical properties and peel strength of the plate, and the extremely low bromine content flame retardant cannot pass, and downstream customers often easily appear flame retardant defective products with unqualified or performance differences in plate making, combined with the bromine nitrogen synergistic resin formed after MDI modification can not only improve flame retardancy, but also improve overall mechanical properties. And the price of MDI has continued to cause a downward trend. If the market control of tetrabromobisphenol A is unstable, synergistic flame retardant can more effectively maintain product quality stability. At the same time, the antimony-free resin made by bromine nitrogen synergistic flame retardant of the present invention is applied to laminates. Under the condition of meeting good flame retardancy, heat resistance, moisture and heat resistance, hygroscopicity, punching processability and excellent electrical properties, it has a high cost-effectiveness advantage and is widely used in household appliances, power substrates, instruments and meters, and various game consoles.

[0110] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a bromine-nitrogen synergistic flame-retardant modified epoxy resin, characterized in that: The following steps are involved: The first epoxy resin, tetrabromobisphenol A and a catalyst are subjected to bulk polymerization to obtain tetrabromobisphenol A epoxy resin; The tetrabromobisphenol A epoxy resin and diphenylmethane diisocyanate are subjected to a modification reaction to obtain an initial modified resin; The initial modified resin, high-bromine epoxy resin and second epoxy resin are mixed to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin, wherein the mass content of bromine element in the high-bromine epoxy resin is ≥46%.

2. The preparation method according to claim 1, characterized in that: The mixing further comprises: The modified mixed system obtained by mixing is diluted with an organic solvent to obtain the bromine-nitrogen synergistic flame-retardant modified epoxy resin.

3. The preparation method according to claim 1, characterized in that: The first epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin and hydrogenated bisphenol A epoxy resin; The purity of tetrabromobisphenol A is ≥99.9%, the acetone color is ≤35APHA, and the free phenol content is ≤15ppm; The mass ratio of the first epoxy resin to the tetrabromobisphenol A is (30-40):(9-10).

4. The preparation method according to claim 1 or 3, characterized in that: The catalyst comprises one or more of tetrabutylammonium bromide, triphenylphosphine, tetramethylammonium chloride and butyltriphenylphosphine bromide; The mass ratio of the first epoxy resin to the catalyst is (30-40): (0.01-0.03); The heat preservation temperature of the bulk polymerization is 160-170° C., and the heat preservation time is 100-150 minutes.

5. The preparation method according to claim 1 or 3, characterized in that: The diphenylmethane diisocyanate includes one or more of MDI50, MDI100 and MDI1102; The mass ratio of the first epoxy resin to the diphenylmethane diisocyanate is (30-40): (7-8); The insulation temperature of the modification reaction is 170-175° C., and the insulation time is 30-90 minutes.

6. The preparation method according to claim 1 or 3, characterized in that: The mass content of bromine in the high-bromine epoxy resin is 46-48%, the epoxy equivalent is 390-410 g / eq, and the hydrolyzable chlorine is ≤500 ppm; The mass ratio of the first epoxy resin to the high-bromine epoxy resin is (30-40): (15-20); The mass ratio of the first epoxy resin to the second epoxy resin is (30-40):(4-6); The mixing heat preservation temperature is 165-170° C., and the heat preservation time is 30-60 minutes.

7. The preparation method according to claim 2, characterized in that: The organic solvent comprises one or more of butanone, propylene glycol methyl ether, acetone and n-butanol; The mass ratio of the first epoxy resin to the organic solvent is (30-40):(20-30).

8. Bromine-nitrogen synergistic flame-retardant modified epoxy resin prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin according to claim 8 in flame-retardant laminates or printed circuit boards.

10. Use of the bromine-nitrogen synergistic flame-retardant modified epoxy resin according to claim 8 in household appliances, electronic computers, mobile phones or transportation vehicles.

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