A diprimary amine ionic flame retardant, synthesis method and application thereof in epoxy resin

Abstract

The present invention belongs to the technical field of epoxy resin materials, and in particular relates to a diprimary amine ionic flame retardant, a synthesis method and its application in epoxy resin. In the present invention, a diprimary amine compound and DOPA are reacted in an alcohol solvent system at room temperature. After the reaction is completed, a white powdery substance is precipitated to synthesize a new flame retardant. In the chemical structure of the flame retardant, the diprimary amine compound and DOPA are combined by electrostatic attraction to form an ionic compound. The flame retardant is directly mixed with bisphenol A diglycidyl ether monomer for the preparation of epoxy resin materials. The new flame retardant synthesized by the present invention has high flame retardant efficiency. When the addition amount is less than 5wt%, the oxygen index of the epoxy resin cured product can be increased to more than 30%, and vertical combustion passes the UL-94V-0 level. More importantly, the flame retardant preparation conditions are mild and the yield is high. The mechanical properties of the epoxy resin modified with it are greatly improved compared with pure EP.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy resin materials, and in particular relates to a diprimary amine ion type flame retardant, a synthesis method and application thereof in epoxy resin. Background Art

[0002] Epoxy resin (EP) is a widely used thermosetting polymer material. Its excellent electrical insulation, corrosion resistance, high thermal stability, low shrinkage, strong adhesion, and mechanical durability make it widely used in electronics, packaging, printed circuit boards, automobiles, adhesives, and surface coatings. However, due to the high content of carbon, hydrogen, and nitrogen elements in EP, it is highly flammable and poses a high safety hazard, limiting its application in many fields. Therefore, enhancing the flame retardancy of EP while maintaining its unique properties has been a major concern.

[0003] Currently, the most common and economical method for improving the flame retardancy of epoxy resins is to add flame retardants, with traditional additives mostly being halogen compounds. However, halogen compounds release large amounts of smoke when burned, are highly toxic, and pose a serious threat to personal safety. Consequently, halogen-based flame retardants have been gradually replaced by halogen-free flame retardants. While numerous external flame retardants reported in the prior art improve the flame retardancy of epoxy resins, these are often accompanied by a decrease in other properties, particularly mechanical properties. Furthermore, most reported flame retardants require multiple reactions during synthesis or have low yields, making them unsuitable for industrial applications.

[0004] Therefore, high-performance flame retardants that have high flame retardant properties and are cheap and economical have become one of the current research hotspots. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a diprimary amine ionic flame retardant, a synthesis method and its application in epoxy resin, aiming to solve some of the problems in the prior art or at least alleviate some of the problems in the prior art.

[0006] The present invention is achieved by providing a diprimary amine ionic flame retardant comprising a compound of the following structural formula:

[0007] R=(CH2) n or Among them, n=3-16.

[0008] The present invention also provides a method for synthesizing the above-mentioned diprimary amine ionic flame retardant, wherein the diprimary amine compound and DOPA are combined with electrostatic attraction to form an ionic compound, and one amino group in the diprimary amine molecule is combined with H +, is positively charged, while the oxygen atom on the DOPA phosphorus hydroxyl group is negatively charged. The end of the compound away from DOPA contains an unbonded primary amine. The chemical equation is as follows:

[0009]

[0010] R=(CH2) n or wherein n = 3 to 16. The carbon chain of the R group has a value of n of 3 to 16 (straight or branched), or a structure in which two benzene rings are connected by a methyl group.

[0011] Furthermore, the reaction is carried out in an alcohol solvent at room temperature, and a white powdery substance is precipitated after the reaction.

[0012] Furthermore, the alcohol solvent is a low-carbon alcohol solvent selected from any one of methanol, ethanol, propanol or butanol.

[0013] Furthermore, the diprimary amine compound and DOPA are dissolved in an alcohol solvent respectively, and then the DOPA liquid is added dropwise to the diprimary amine compound liquid to react.

[0014] Furthermore, the molar ratio of the diprimary amine compound to DOPA is 1-1.2:0.8-1.0; the reaction temperature is room temperature (23-30°C); and the reaction time is 7-12 hours. Preferably, the reaction temperature is 25-30°C and the reaction time is 8 hours.

[0015] The present invention also provides use of the above-mentioned diprimary amine ion flame retardant in the preparation of epoxy resin.

[0016] Furthermore, the epoxy resin is selected from any one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, and glycidyl amine epoxy resin, preferably bisphenol A epoxy resin.

[0017] Furthermore, after bisphenol A diglycidyl ether and the P / N / S flame retardant are fully reacted, a curing agent is added to obtain an epoxy resin with improved performance. The curing agent is preferably 4,4'-diaminodiphenylmethane (DDM).

[0018] Furthermore, the addition amount of the diprimary amine ionic flame retardant is 0.5-10 wt%, preferably 2-4 wt%.

[0019] The present invention uses diprimary amine and DOPA as main raw materials to synthesize a new compound AP through a one-step reaction. When used for flame retardancy of epoxy resin, when the addition amount is only 4wt%, it can achieve the best flame retardancy effect UL-V0 level, and the mechanical properties are greatly improved compared with pure EP. Due to its unique properties and simple preparation method, it has considerable potential application value.

[0020] In summary, the advantages and positive effects of the present invention are:

[0021] 1. Compared with the existing technology, this synthesis reaction method is simple, has high yield, no other by-products, mild reaction conditions, safe operation, low cost, and has great industrial value.

[0022] 2. Compared with the prior art, the flame retardant containing the diprimary amine ionic compound prepared by the present invention has higher flame retardant efficiency. When the addition amount is 4wt%, the oxygen index of the epoxy resin cured product can be increased to 35.1%, and the vertical combustion passes the UL-94V-0 level. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the infrared image of the diprimary amine ion compound;

[0024] Figure 2 It is a diprimary amine ionic compound 1 H NMR and 31 P NMR spectrum. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples. Unless otherwise specified, the equipment and reagents used in each example and test example can be obtained from commercial sources. The specific examples described herein are only used to illustrate the present invention and are not intended to limit the present invention.

[0026] Based on the information contained in this application, it will be readily apparent to those skilled in the art that various changes can be made to the precise description of the present invention without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present invention is not limited to the defined processes, properties, or components, as these embodiments and other descriptions are provided merely to illustrate specific aspects of the present invention. In fact, various changes that a person skilled in the art or related fields would clearly be able to make to the embodiments of the present invention are encompassed within the scope of the appended claims.

[0027] For a better understanding of the present invention and not to limit the scope of the present invention, all numbers used in this application to express amounts, percentages, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may vary depending on the desired properties to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0028] The invention discloses a diprimary amine ion type flame retardant, a synthesis method and application of the same in epoxy resin.

[0029] It should be noted that the material parts in the following examples are by weight. The limiting oxygen index in the examples was measured using an HC-2C oxygen index tester in accordance with GB / T 2406-1993, and vertical combustion was measured using a CZF-2 vertical combustion apparatus in accordance with GB / T 2408-1996. The technical solutions of the present invention will be described clearly and completely below in conjunction with the examples of the present invention.

[0030] Example 1 Synthesis of diprimary amine ionic flame retardant AP

[0031] Accurately weigh 5.9479 g of 4,4'-diaminodiphenylmethane into a 250 mL three-necked flask, add 50 mL of anhydrous ethanol, and completely dissolve under magnetic stirring at room temperature. Dissolve 6.9600 g of 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPA) in 50 mL of anhydrous ethanol. Add the mixture dropwise at a rate of 1 drop / s using a constant pressure funnel. Allow to react at room temperature for 8 hours. Upon completion, a white powder precipitates. Filter, wash several times with anhydrous ethanol or deionized water, dry, and weigh to obtain a white solid weighing 9.6443 g, with a yield of 74.72%. The chemical equation for the synthesis reaction is as follows:

[0032]

[0033] R=(CH2) n or Among them, n=3-16.

[0034] Figure 1 This is the infrared spectrum of the synthesized compound AP (the product synthesized by the reaction of DDM and DOPA). 1 H NMR and 31 PNMR diagram. Figure 1 Medium 3500-3250cm -1 The absorption peak at 3058 cm is the stretching vibration of primary amine. -1 The absorption peak at 2700-2380cm is the stretching vibration of benzene ring CH. -1 The absorption peak at NH 3+ Stretching vibration, 1722cm -1 The absorption peak at 1677cm-1 is the overtone of the benzene ring, and the absorption peak at 1677cm-1 is the NH3 + The asymmetric angle vibration of NH 3+ δ as Asymmetric deformation vibration, 1550-1450cm -1 The absorption peak at NH 3+ δs Symmetrical deformation vibration, 1203cm -1 The absorption peak at 1130-975cm is the stretching vibration of P=O. -1 The absorption peak at 800-710 cm is the in-plane bending vibration of the aromatic ring CH. -1 The absorption peak at is the out-of-plane bending vibration of the benzene ring CH. Figure 2 of 1 In the HNMR spectrum, the broad peak b at 8.70 ppm is attributed to NH 3+ The peak at 6.90-7.95 ppm is attributed to the H on the benzene ring, while the peak b at 3.81 ppm is attributed to the H on the methylene at a. 31 The single absorption peak of PNMR also shows that the reactants are in a 1:1 reaction. The above characterization clearly shows that AP was successfully synthesized. Compound AP is formed by diprimary amine and DOPA in the form of ionic bonds, in which the amino group in the diprimary amine molecule binds to H + , is positively charged, while the oxygen atom on the DOPA phosphorus hydroxyl group is negatively charged, and the two are combined into an ionic compound due to electrostatic attraction.

[0035] Example 2 Preparation of epoxy resin EP / 2AP

[0036] Under vacuum conditions, 77.8% by mass of bisphenol A diglycidyl ether (DGEBA) was evacuated at 95°C until there were no bubbles. Then, 2% by mass of powdered AP (AP was prepared by the reaction of DDM and DOPA) was quickly added. After rapid stirring to allow AP and EP to fully react, 20.2% by mass of curing agent DDM was added. The resulting liquid was poured into a polytetrafluoroethylene (PTFE) mold and cured at 100°C and 150°C for 2 hours each to obtain an epoxy resin with an oxygen index test result of 31.8% and a vertical burning rating of UL-94V-1.

[0037] Example 3 Preparation of epoxy resin EP / 4AP

[0038] Under vacuum conditions, 76.2% by mass of bisphenol A diglycidyl ether (DGEBA) was evacuated at 95°C until there were no bubbles. Then, 4.0% by mass of powdered AP (AP was prepared by the reaction of DDM and DOPA) was quickly added. After rapid stirring to allow AP and EP to fully react, 19.8% by mass of curing agent DDM was added. The resulting liquid was poured into a polytetrafluoroethylene (PTFE) mold and cured at 100°C and 150°C for 2 hours respectively to obtain an epoxy resin with an oxygen index test result of 35.1% and a vertical burning rating of UL-94V-0.

[0039] Example 4 Preparation of epoxy resin EP / 2AP'

[0040] Under vacuum conditions, 77.8% by mass of bisphenol A diglycidyl ether (DGEBA) was evacuated at 95°C until no bubbles were present. Then, 2% by mass of powdered AP' (AP' was prepared by reacting 1,10-diaminodecane with DOPA in the absence of a solvent as described in Example 1) was rapidly added and stirred rapidly to allow AP' and EP to fully react. 20.2% by mass of a curing agent DDM was added, and the resulting liquid was poured into a polytetrafluoroethylene (PTFE) mold. The epoxy resin was cured at 100°C and then at 150°C for 2 hours to obtain an epoxy resin having an oxygen index test result of 31.2% and a vertical flammability rating of UL-94V-1.

[0041] Example 5 Preparation of epoxy resin EP / 4AP'

[0042] Under vacuum conditions, 76.2% by mass of bisphenol A diglycidyl ether (DGEBA) was evacuated at 95°C until there were no bubbles. Then, 4% by mass of powdered AP' (AP' was prepared by the reaction of 1,10-diaminodecane and DOPA) was quickly added and stirred rapidly to allow AP' and EP to fully react. Then, 19.8% by mass of curing agent DDM was added, and the resulting liquid was poured into a polytetrafluoroethylene (PTFE) mold. The epoxy resin was cured at 100°C and 150°C for 2 hours respectively to obtain an epoxy resin with an oxygen index test result of 32.4% and a vertical burning rating of UL-94V-0.

[0043] Comparative Example Preparation of Pure EP

[0044] Under vacuum conditions, 79.4% by mass of bisphenol A diglycidyl ether (DGEBA) was evacuated at 95°C until there were no bubbles. 20.6% by mass of curing agent DDM was added and stirred until uniform. The resulting liquid was poured into a polytetrafluoroethylene (PTFE) mold and cured at 100°C and 150°C for 2 hours respectively to obtain an epoxy resin. The oxygen index test result was 26.5%, and the vertical burning rating was UL-94 no rating.

[0045] The mechanical properties of the epoxy resins prepared in the examples and comparative examples were also tested in this application. The relevant methods were as follows: tensile test and three-point bending test were carried out on a CMT6103 universal testing machine according to the methods of GB / T 1040.2-2006 and GB / T 9341-2008 respectively. 3 The dumbbell-shaped specimen of the three-point bending test has a specimen size of 80×10×4mm 3 The value of each test is taken as the average of three tests. The test results are shown in Table 1 below.

[0046] Table 1: Effect of the diprimary amine ion-containing compound (AP) of the present invention on the mechanical properties of epoxy resin

[0047]

[0048] As shown in the table above, the tensile strength, elongation at break, flexural strength, and flexural modulus of the epoxy resin obtained by adding the novel diprimary amine ion-containing flame retardant of the present invention to epoxy resin all increase with increasing the amount of AP compound added to the epoxy resin. At a 4% addition, the flexural strength is 72% higher than that of pure epoxy resin. This epoxy resin exhibits high flame retardancy and excellent mechanical properties. While the structure of this flame retardant has not been reported in the literature, this patent provides a low-cost, simple, and highly efficient preparation method for epoxy resin flame retardants, which has potential application value.

[0049] The diprimary amines described herein include all diprimary amine-containing raw materials as described in the patent descriptions. Their structural characteristics are that, in addition to containing an ionic bond, they also have an unbonded primary amine at one end. Examples are not listed here. In addition to the synthesis method, additives synthesized by other methods and having the same structural characteristics are also included.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A diprimary amine ionic flame retardant, characterized in that: Including compounds with the following structural formula: ， R=(CH2) n or , where n=3-16.

2. A method for synthesizing the diprimary amine ionic flame retardant according to claim 1, characterized in that: The diprimary amine compounds and DOPA combine by electrostatic attraction to form ionic compounds. The chemical formula is as follows: ， R=(CH2) n or , where n=3-16.

3. The method for synthesizing a diprimary amine ionic flame retardant according to claim 2, wherein: The reaction is carried out in an alcohol solvent at room temperature, and a white powdery substance is precipitated after the reaction.

4. The method for synthesizing a diprimary amine ionic flame retardant according to claim 3, wherein: The alcohol solvent is any one of methanol, ethanol, propanol or butanol.

5. The method for synthesizing a diprimary amine ionic flame retardant according to claim 3, wherein: The diprimary amine compound and DOPA are dissolved in an alcohol solvent respectively, and then the DOPA liquid is added dropwise to the diprimary amine compound liquid to react.

6. The method for synthesizing a diprimary amine ionic flame retardant according to claim 3, wherein: The molar ratio of the diprimary amine compound to DOPA is 1-1.2:0.8-1.0; the reaction temperature is room temperature 23-30°C; and the reaction time is 7-12 hours.

7. Use of the diprimary amine ionic flame retardant according to claim 1 in the preparation of epoxy resin.

8. The use according to claim 7, characterized in that: The epoxy resin is selected from any one of glycidyl ether epoxy resin, glycidyl ester epoxy resin and glycidyl amine epoxy resin.

9. The use according to claim 8, characterized in that: After bisphenol A diglycidyl ether and the diprimary amine ionic flame retardant are fully reacted, a curing agent is added to obtain an epoxy resin with improved performance.

10. The use according to claim 9, characterized in that: The addition amount of the diprimary amine ionic flame retardant is 0.5-10 wt %.

Images