A brominated epoxy resin bio-based derivative and its preparation method and application

Abstract

The present invention provides a brominated epoxy resin bio-based derivative, a preparation method and an application thereof, which solve the problem that the existing brominated epoxy resin is completely derived from petroleum and relies on non-renewable petroleum resources. A brominated epoxy resin bio-based derivative containing a carbon fifteen flexible group with Br and P synergy is synthesized, and has a structural formula of the following formula (I): #imgabs0#, wherein R1 and R2 are independently a bond-line structure shown in any one of the following formulas (II), (III), (IV) and (V): or, R1 and R2 are independently a bond-line structure shown in any one of the following formulas (V), (VII), (VIII) and (IX): #imgabs1#. The present invention also discloses a preparation method and an application of the brominated epoxy resin bio-based derivative, which can be widely used in the field of polymer material technology.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a bio-based derivative of a brominated epoxy resin, a preparation method thereof, and an application thereof. Background Art

[0002] Brominated epoxy resin is a type of epoxy resin material that contains bromine in its molecular structure. It not only has the excellent electrical insulation and adhesion properties of general epoxy resins, but also has excellent self-flame retardancy and is widely used in various flame-retardant electronic components.

[0003] Brominated epoxy resin is prepared by substitution reaction of tetrabromobisphenol A and epichlorohydrin. Although brominated epoxy resin has the above-mentioned excellent properties, the production of epoxy monomer mainly depends on non-renewable petroleum resources, which is not conducive to limiting greenhouse gas emissions and does not meet the requirements of green and sustainable development. Therefore, the research and development of bio-based epoxy resin is of great significance. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the above-mentioned technology and provide a bio-based derivative of brominated epoxy resin and a preparation method and application thereof.

[0005] To this end, the present invention provides a brominated epoxy resin bio-based derivative having the following structural formula (I):

[0006]

[0007] , wherein R1 and R2 are independently a bond-line structure represented by any one of the following formulas (II), (III), (IV), and (V); or, R1 and R2 are independently a bond-line structure represented by any one of the following formulas (V), (VII), (VIII), and (IX):

[0008]

[0009] The present invention also provides a method for preparing a bio-based derivative of a brominated epoxy resin, which comprises: reacting a brominated epoxy resin and cardanol in the presence of a catalyst to obtain a brominated epoxy resin modified with cardanol; and then performing an epoxidation reaction to obtain an epoxidized cardanol-modified brominated epoxy resin, that is, obtaining the bio-based derivative of the brominated epoxy resin as described above, which has a structural formula as shown in formula (I), wherein R1 and R2 are independently a bond-line structure shown in any one of formulas (V), (VII), (VIII), and (IX).

[0010] Cardanol has reactive phenolic hydroxyl groups and unsaturated long alkyl chains. As an agricultural byproduct, it is extracted from natural cashew nut shell oil and has the advantages of abundant sources, low prices, and renewable. Usually, cardanol is a mixture of four alkylphenols with different saturations, namely 3% saturated hydrocarbon cardanol, 42% monoolefin cardanol, 17% diene cardanol, and 38% triolefin cardanol. Its structure is shown below:

[0011]

[0012] It can be seen that the epoxidation of the brominated epoxy resin modified with cardanol is actually epoxidation on the pentadecyl side chain of cardanol.

[0013] The epoxidized cardanol-modified brominated epoxy resin is subjected to an addition reaction with DOPO to obtain a brominated epoxy resin bio-based derivative as described in the above structural formula.

[0014] The raw material DOPO is the abbreviation of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Compared with halogen flame retardants, it is a new reactive phosphorus-containing flame retardant. Its structure contains PH bonds and is extremely active to olefins, epoxy bonds and carbonyl groups. The phosphorus-containing epoxy resin synthesized with it is halogen-free, smokeless, non-toxic, non-migrating and has long-lasting flame retardant properties.

[0015] Preferably, the preparation method of the cardanol-modified brominated epoxy resin comprises: heating the brominated epoxy resin and excess cardanol to 95-105° C., adding a catalyst and stirring to dissolve, and continuing to heat to 170-190° C., and after the reaction is completed, obtaining the cardanol-modified brominated epoxy resin.

[0016] Preferably, the molar ratio of the brominated epoxy resin to cardanol is 1:2 to 1:2.1.

[0017] Preferably, the catalyst is triphenylphosphine, and the amount of triphenylphosphine added is 0.1-0.5% of the total mass. The total mass refers to the sum of the weights of all raw materials added to prepare the cardanol-modified brominated epoxy resin under the action of the catalyst.

[0018] Preferably, the preparation method of the epoxidized cardanol-modified brominated epoxy resin comprises: dissolving the brominated cardanol-modified epoxy resin in an organic solvent, adding m-chloroperbenzoic acid (preferably in batches) at 25 to 30° C., filtering after the reaction is completed, washing the filtrate to neutrality, and then distilling off the organic solvent to obtain the epoxidized cardanol-modified brominated epoxy resin.

[0019] Preferably, the organic solvent is one or more of dichloromethane, dichloroethane, dichloropropane, trichloroethane and chloroform.

[0020] Preferably, the method for washing the filtrate to neutrality is: washing the filtrate with a sodium bisulfite solution to remove excess meta-chloroperbenzoic acid, continuing to wash with sodium carbonate to neutralize excess sodium bisulfite, and finally washing with water until neutrality.

[0021] Preferably, it has a synergistic flame retardant effect of Br and P; it comprises: subjecting the obtained epoxidized cardanol-modified brominated epoxy resin to an addition reaction with DOPO at 140-180°C to obtain the brominated epoxy resin bio-based derivative as claimed in claim 1, which has a structural formula as shown in formula (I), wherein R1 and R2 are independently a bond-line structure shown in any one of formulas (II), (III), (IV) and (V).

[0022] Preferably, the amount of the epoxidized cardanol-modified brominated epoxy resin reacted with DOPO is such that the molar ratio of epoxy group to DOPO is 1:1.

[0023] An application of a brominated epoxy resin bio-based derivative, wherein the brominated epoxy resin bio-based derivative as described in the above chemical formula structure is used as a polymer flame retardant in flame-retardant epoxy polymer materials.

[0024] The beneficial effects of the present invention are as follows: the present invention provides a brominated epoxy resin bio-based derivative, a preparation method thereof, and an application thereof, wherein the brominated epoxy resin bio-based derivative is applied as a polymer flame retardant to flame-retardant epoxy polymer materials, thereby changing the limitation that the brominated epoxy resin is all derived from petroleum-based materials. The raw material cardanol is the main component of cashew nut shell liquid, which is an important agricultural and sideline product of cashew production, with a wide range of sources and huge reserves. Therefore, the use of abundant and low-cost natural compounds as raw materials to synthesize brominated epoxy resin bio-based derivatives is conducive to reducing the amount of petroleum-based raw materials in the product, which meets the definition of green chemistry.

[0025] In addition, the bio-based derivative of the brominated epoxy resin of the present invention effectively combines the higher flame retardant effect of the brominated flame retardant, the better toughening effect and active reaction groups of cardanol and the DOPO reactive phosphorus-containing flame retardant, combines the brominated epoxy resin, cardanol and DOPO, effectively improves the mechanical properties of the flame-retarded resin, and synthesizes a new polymer flame retardant for use in flame-retardant epoxy polymer materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 The infrared spectra of the brominated epoxy resin modified with cardanol prepared in Example 2 and the epoxidized brominated epoxy resin modified with cardanol prepared in Example 3;

[0028] Figure 2 The infrared spectra of DOPO and the bio-based derivative of brominated epoxy resin prepared in Example 4. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products unless otherwise specified. Among them, cardanol was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. with a purity greater than 99%; epoxy resin E51 was purchased from Shandong Jiufeng Chemical Co., Ltd.; curing agent C19 was purchased from Shandong Jiufeng Chemical Co., Ltd.

[0030] Example

[0031] Embodiment 1:

[0032] Preparation of brominated epoxy resin:

[0033] Weigh 410g of epichlorohydrin and 400g of tetrabromobisphenol A into a four-necked flask, install a reflux condenser and a thermometer, start heating, add 1.2g of benzyltriethylammonium chloride, stir and heat to 90°C, react for 2.5h, and remove excess epichlorohydrin by reduced pressure distillation; cool to 60°C, add 100g of solvent toluene, stir evenly, add 25% sodium hydroxide solution evenly within 1h and stir evenly, and react for 5h; then add 300g of solvent toluene for extraction, and add 400g of water to wash while hot to wash away the generated sodium chloride, and separate the liquids; then add 400g of hot water at 60°C for two consecutive times to wash, and separate the liquids; remove the solvent toluene by reduced pressure distillation to obtain a brominated epoxy resin.

[0034] The synthesized brominated epoxy resin has no fluidity at room temperature and exists in a form close to solid, to the extent that a viscometer cannot test it. In addition, experimental tests (hydrochloric acid-acetone method) show that the epoxy equivalent of the brominated epoxy resin is 350 g / equivalent (epoxy value is 0.286), from which it can be seen that the average molecular weight of the brominated epoxy resin prepared in Example 1 is 700.

[0035] It should be noted that:

[0036] (1) Epoxy equivalent refers to the number of grams of epoxy resin containing one equivalent of epoxy groups, and the unit is [g / equivalent], that is, the average molecular weight of epoxy resin divided by the number of epoxy groups contained in one molecule. Therefore, the epoxy equivalent value of brominated epoxy resin is 1 / 2 of the average molecular weight of brominated epoxy resin.

[0037] (2) The above-mentioned benzyltriethylammonium chloride can be used as a quaternary ammonium salt catalyst, and tetrabutylammonium hydrogen sulfate can also be used instead, or benzyltriethylammonium chloride and tetrabutylammonium hydrogen sulfate can be used together.

[0038] Example 2

[0039] Preparation of cardanol-modified brominated epoxy resin:

[0040] 175.50 g (0.25 mol) of the brominated epoxy resin prepared in Example 1 and 154.87 g (0.51 mol) of cardanol were weighed and added to a four-necked flask, heated to 100° C., stirred to dissolve, 1.32 g of triphenylphosphine catalyst was added to the reaction flask, and the temperature was continued to rise to 180° C. and reacted for 90 minutes. After the reaction was completed, a brominated epoxy resin modified with cardanol in a flowing state was obtained.

[0041] The brominated epoxy resin modified with cardanol synthesized in Example 2 was tested by the hydrochloric acid-acetone method to have an epoxy equivalent of 2941 g / equivalent (the epoxy value was 0.034, and the epoxy functional groups of the brominated epoxy resin were basically considered to have been completely reacted.)

[0042] In order to further verify the successful synthesis of the brominated epoxy resin modified by cardanol, the brominated epoxy resin modified by cardanol obtained in Example 2 was characterized by infrared spectroscopy. Figure 1 shown.

[0043] from Figure 1 It can be seen from the infrared spectrum of Example 2 that at 1600-1447 cm -1 The absorption bands at 3008, 911 and 871 cm are the C=C stretching vibration peaks on the aromatic ring skeleton and unsaturated double bonds. -1 The peaks are the CH stretching vibration peak and the out-of-plane bending vibration absorption peak on C=C. The appearance of the above functional groups indicates the synthesis of brominated epoxy resin modified with cardanol.

[0044] Example 3

[0045] Preparation of epoxidized cardanol-modified brominated epoxy resin:

[0046] Weigh 53.91g of the brominated epoxy resin modified by cardanol prepared in Example 2 and 320g of dichloromethane into a three-necked flask, keep it at 26°C, add 25.98g of m-chloroperbenzoic acid in batches, add 130g of dichloromethane in the process, and then stir at 30°C for 3 hours. After the reaction is completed, filter it with suction, wash the filtrate with a 5% sodium bisulfite solution twice, wash it with a 5% sodium carbonate solution three times, and finally wash it with pure water until it is neutral. Dichloromethane is distilled out at 50°C to obtain a brown-black viscous epoxidized cardanol-modified brominated epoxy resin.

[0047] The epoxy equivalent of the brominated epoxy resin modified with epoxidized cardanol in Example 3 was 537.6 g / equivalent when tested by the hydrochloric acid-acetone method (the epoxy value was 0.186, and it was calculated that about 2.46 mol of double bonds were oxidized to epoxy groups per 1 mol of the brominated epoxy resin modified with cardanol).

[0048] In order to further verify that the brominated epoxy resin modified with cardanol was epoxidized, the brominated epoxy resin modified with cardanol obtained in Example 3 was characterized by infrared spectroscopy. The infrared spectrum formed was as follows: Figure 1 shown.

[0049] Depend on Figure 1 It can be seen that compared with the infrared spectra of Example 2, 914 cm -1 The end epoxy absorption peak is 848 cm -1 The absorption peak of the fatty chain epoxy group is at 3008cm -1 The CH absorption peak on the side chain disappeared. The changes in the above functional groups indicated that the double bonds on the side chains of the brominated epoxy resin modified with cardanol underwent epoxidation.

[0050] Example 4

[0051] Preparation of bio-based derivatives of brominated epoxy resins:

[0052] 26.5 g of the epoxidized cardanol-modified brominated epoxy resin prepared in Example 3 and 10.68 g of DOPO were weighed and added into a three-necked flask, and reacted at 160° C. for 6 hours. After the reaction, a yellow transparent solid was obtained.

[0053] In order to further verify the successful synthesis of epoxidized cardanol-modified brominated epoxy resin and DOPO, the sample obtained in Example 4 was characterized by infrared spectroscopy. Figure 2shown.

[0054] from Figure 2 It can be seen that compared with the infrared spectra of Example 4 and DOPO, the -1 POC stretching vibration peak at 1585cm -1 The P-Ph stretching vibration peak at 2385 cm-1 still exists in the infrared spectrum of Example 4, while the characteristic peak of DOPO, PH bond, is 2385 cm-1. -1 The absorption peak of disappeared in Example 4, proving that DOPO reacted with the epoxidized brominated epoxy resin to synthesize a bio-based derivative of the brominated epoxy resin.

[0055] In this Example 4, the PH bond in DOPO has a certain activity because it is connected to the strong electron-withdrawing group P-0, and DOPO can form a phosphorus anion and react as a nucleophilic reagent. The epoxy group has a high activity due to its high tension in the three-membered ring, and is easy to open the ring. The carbon atoms in the ring are attacked by the nucleophilic reagent to form a stable compound.

[0056] Application Examples

[0057] The brominated epoxy resin modified with cardanol prepared in Example 2 and the bio-based derivative of brominated epoxy resin prepared in Example 4 were respectively used as polymer flame retardants in flame-retardant epoxy polymer materials, and their physical properties were tested by tensile and unnotched impact tests.

[0058] Application Example 1

[0059] (1) Weigh 20.0 g of the brominated epoxy resin modified with cardanol prepared in Example 2 and mix it with 100.0 g of epoxy resin E51, then add 0.2 g of defoamer B-459, place it in a water bath at 80° C. and heat it for 30 min to obtain an epoxy resin mixed solution for later use;

[0060] (2) Place 50.0 g of curing agent C19 in a water bath at 80° C. and heat for 30 min. Set aside;

[0061] (3) Place the stainless steel mold in a drying oven and preheat to 80°C for use;

[0062] (4) Pour the curing agent C19 heated in a water bath in step (2) into the epoxy resin mixture in step (1), stir thoroughly, and then pour into the stainless steel mold in step (3). Then, place the mold in an oven at 80° C. for 2 hours and then take it out. After curing at room temperature for 4 hours, the cured product in the mold is slowly cooled to room temperature and then demolded to obtain a tensile test specimen and a notched impact test specimen.

[0063] Description: The stainless steel mold is provided with a cavity that matches the shape and size of the tensile test specimen and the unnotched impact test specimen.

[0064] Application Example 2

[0065] The only difference from Application Example 2 is that 20.0 g of the brominated epoxy resin modified with cardanol prepared in Example 2 is replaced with 20.0 g of the bio-based derivative of the brominated epoxy resin prepared in Example 4. The other contents are exactly the same as those in Application Example 2 and will not be repeated here.

[0066] The tensile test specimens and the unnotched impact test specimens prepared in the above-mentioned application examples 1 and 2 were subjected to a tensile test and an unnotched impact test, respectively.

[0067] (1) Tensile test

[0068] Test standard for tensile test: "Determination of Tensile Properties of Plastics" (GB / T 2567-2021).

[0069] Sample size: Prepare according to GB / T 2567-2021. The sample needs to be made into a dumbbell shape.

[0070] Test method: Clamp the sample so that the long axis of the sample is consistent with the tensile direction of the center line of the upper and lower clamps, and continuously load it at a certain speed until it fails, and read the failure load value. The loading speed is 2mm / min, and each group of samples is not less than 5. If the fracture point of the sample is not in the middle parallel part, the sample is invalid. The average value of all test data is the final test result. The test results are shown in Table 1 below.

[0071] Table 1: Tensile test results of application examples 1 and 2

[0072] Application Examples Tensile strength / MPa Elongation at break / % Application Example 1 34.37 5 Application Example 2 36.68 4.84

[0073] (2) Unnotched impact test

[0074] Test standard for unnotched impact test: GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams".

[0075] Sample specifications: length (80±2) mm, width (10±0.2) mm, thickness (4±0.2) mm, and span 60 mm.

[0076] Test method: Place the test piece symmetrically and vertically against the support, with the pendulum impact speed at 2.9m / s, release the pendulum steadily, and read the energy absorbed by the impact test. Each group of samples shall be no less than 5. The average value of all test data is the final test result. See Table 2 below for the test results.

[0077] Table 2: Unnotched impact test results of application examples 1 and 2

[0078] Application Examples <![CDATA[Impact strength / KJ / m 2 > Application Example 1 9.85 Application Example 2 11.87

[0079] It can be seen from the test data in Tables 1 and 2 that the tensile properties and impact properties of the synthesized brominated epoxy resin bio-based derivatives are better than those of the brominated epoxy resin modified with cardanol due to the introduction of the rigid structure of the DOPO group. The brominated epoxy resin bio-based derivatives effectively combine the flame retardant effect of the brominated flame retardant, the good toughening effect of cardanol and the DOPO reactive phosphorus-containing flame retardant, and the mechanical properties of the flame-retarded resin are improved.

[0080] It should be noted that:

[0081] (1) In the preparation process of brominated epoxy resin modified by cardanol, the amount of brominated epoxy resin and excess cardanol added, the reaction time, and the amount of catalyst used can be adjusted according to the actual situation. In the actual production process, the reaction time is usually 1 to 3 hours; the molar ratio of brominated epoxy resin to cardanol is 1:2 to 1:2.1; triphenylphosphine is used as a catalyst, and the amount of triphenylphosphine added is 0.1 to 0.5% of the total mass.

[0082] (2) In the preparation process of epoxidized cardanol-modified brominated epoxy resin, the amount of raw materials added, reaction time, type of organic solvent, mass fraction of washing liquid and number of washing times can be adjusted according to actual conditions. In the actual production process, the reaction time is usually 2 to 4 hours; the organic solvent is dichloromethane, dichloroethane, dichloropropane, trichloroethane, trichloromethane, etc.; the filtrate is washed 2 to 3 times with a mass fraction of 5% sodium bisulfite solution, and then washed 3 times with a mass fraction of 5% sodium carbonate, and finally washed with water 3 to 5 times until neutral.

[0083] (3) In the preparation process of the bio-based derivative of brominated epoxy resin, the amount of raw materials added, the reaction time, etc. can be adjusted according to the actual situation. Usually, the molar ratio of the epoxidized cardanol-modified brominated epoxy resin to DOPO is 1:1; the reaction time is 5 to 8 hours; the reaction container is preferably a flask with a stirring device, a thermometer and a condensation collection device.

[0084] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A brominated epoxy resin bio-based derivative, characterized in that: It has the structural formula (I): ， Wherein, R1 and R2 are independently a bond-line structure shown in any one of the following formulas (II), (III), (IV), and (V); or, R1 and R2 are independently a bond-line structure shown in any one of the following formulas (V), (VII), (VIII), and (IX): In formula (II), formula (III), formula (IV), formula (V), formula (VII), formula (VIII) and formula (IX), "*" represents the linking site.

2. A method for preparing a bio-based derivative of brominated epoxy resin, characterized in that: It includes: The brominated epoxy resin and cardanol are reacted under the action of a catalyst to obtain a brominated epoxy resin modified with cardanol; Then, an epoxidation reaction is carried out to obtain an epoxidized cardanol-modified brominated epoxy resin, that is, the brominated epoxy resin bio-based derivative as claimed in claim 1, which has a structural formula as shown in formula (I), wherein R1 and R2 are independently a bond-line structure shown in any one of formulas (V), (VII), (VIII) and (IX).

3. The method for preparing a bio-based derivative of brominated epoxy resin according to claim 2, characterized in that: The preparation method of the cardanol-modified brominated epoxy resin comprises: heating the brominated epoxy resin and excess cardanol to 95-105° C., adding a catalyst and stirring to dissolve, and continuing to heat to 170-190° C. After the reaction is completed, the cardanol-modified brominated epoxy resin is obtained.

4. The method for preparing a brominated epoxy resin bio-based derivative according to claim 3, characterized in that: The molar ratio of the brominated epoxy resin to cardanol is 1:2 to 1:2.

1.

5. The method for preparing a bio-based derivative of brominated epoxy resin according to claim 2, characterized in that: The catalyst is triphenylphosphine, and the added amount of triphenylphosphine is 0.1-0.5% of the total mass.

6. The method for preparing a bio-based derivative of brominated epoxy resin according to claim 2, characterized in that: The preparation method of the epoxidized cardanol-modified brominated epoxy resin comprises: dissolving the brominated cardanol-modified epoxy resin in an organic solvent, adding meta-chloroperbenzoic acid at 25-30° C., filtering after the reaction is completed, washing the filtrate to neutrality, and then distilling to remove the organic solvent to obtain the epoxidized cardanol-modified brominated epoxy resin.

7. The method for preparing a brominated epoxy resin bio-based derivative according to claim 6, characterized in that: The organic solvent is one or more of dichloromethane, dichloroethane, dichloropropane, trichloroethane and chloroform.

8. The method for preparing a bio-based derivative of brominated epoxy resin according to claim 6, characterized in that: The method for washing the filtrate to neutrality is: washing the filtrate with a sodium bisulfite solution to remove excess meta-chloroperbenzoic acid, continuing to wash with sodium carbonate to neutralize excess sodium bisulfite, and finally washing with water until neutrality.

9. The method for preparing a brominated epoxy resin bio-based derivative according to claim 2, characterized in that: It has synergistic flame retardant effect of Br and P; The method comprises: subjecting the obtained epoxidized cardanol-modified brominated epoxy resin to an addition reaction with DOPO at 140 to 180° C. to obtain the brominated epoxy resin bio-based derivative as claimed in claim 1, which has a structural formula as shown in formula (I), wherein R1 and R2 are independently a bond-line structure shown in any one of formulas (II), (III), (IV) and (V).

10. An application of a bio-based derivative of brominated epoxy resin, characterized in that: The brominated epoxy resin bio-based derivative as claimed in claim 1 is used as a polymer flame retardant in flame-retardant epoxy polymer materials.

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