High-temperature-resistant epoxy molding compound for aviation connector and preparation method of high-temperature-resistant epoxy molding compound

Abstract

The invention discloses a high-temperature-resistant epoxy molding compound for aviation connectors and a preparation method of the high-temperature-resistant epoxy molding compound, and belongs to the technical field of epoxy resin compositions. The high-temperature-resistant epoxy molding compound for the aviation connector is prepared from the following components in percentage by weight: 10 to 25 percent of epoxy resin, 5 to 15 percent of polymethyl silicone resin, 3 to 15 percent of curing agent, 1.2 to 3 percent of curing accelerator, 20 to 40 percent of inorganic filler, 0.8 to 1.5 percent of release agent, 20 to 35 percent of high-silica glass fiber, 3 to 10 percent of flame retardant and 0 to 1 percent of pigment. A test piece formed by injection molding of the epoxy molding compound still maintains enough strength after being heated to the high temperature of 1000 DEG C for 5 minutes, the retention rate of impact strength can reach 45% or above, the retention rate of bending strength can reach 30% or above, the retention rate of electrical strength can reach 40% or above, and use safety can be ensured.

Description

Technical Field

[0001] The invention relates to an epoxy resin composition, in particular to a high temperature resistant epoxy molding compound for aviation connectors and a preparation method thereof. Background Art

[0002] Epoxy molding compound, also known as epoxy resin molding compound or epoxy plastic encapsulation compound, is a powdered or granular molding compound made of epoxy resin as the base resin, phenolic resin as the curing agent, fillers, and a variety of additives.

[0003] Epoxy molding compound has certain heat resistance and corrosion resistance, and is an ideal material for aviation connectors. However, some aviation connectors have higher requirements for heat resistance. For example, during use, after the temperature rises from room temperature to 1000°C and lasts for 2 minutes or even longer, it is required to maintain sufficient mechanical strength (impact strength retention rate is not less than 40%, bending strength retention rate is not less than 5%) and electrical strength (electrical strength retention rate is not less than 8%), so as to ensure the safety of parts. Existing connectors molded by ordinary epoxy molding compound will more or less crack, carbonize, and have a significant decrease in electromechanical strength after this heating process, which cannot meet the use requirements of special aviation connectors. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a high temperature resistant epoxy molding compound for aviation connectors which can maintain sufficient mechanical strength and electrical strength after being rapidly heated to 1000°C for 5 minutes and a preparation method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A high temperature resistant epoxy molding compound for aviation connectors, which is made of the following components by weight percentage:

[0007] Epoxy resin 10-25%;

[0008] Polymethyl silicone resin 5-15%;

[0009] Curing agent 3-15%;

[0010] Curing accelerator 1.2-3%;

[0011] Inorganic filler 20-40%;

[0012] Release agent 0.8~1.5%;

[0013] High silica glass fiber 20-35%;

[0014] Flame retardant 3-10%;

[0015] Pigment 0-1%;

[0016] in,

[0017] The epoxy resin is one or a combination of two or more selected from biphenyl crystalline epoxy resin, phenol biphenyl epoxy resin and biphenyl phenol self-flame retardant epoxy resin;

[0018] The curing agent is bisphenol A phenolic resin;

[0019] The curing accelerator is one or a combination of two or more selected from triphenylphosphine, tri(dimethylamino)phenylphosphine, triethylphosphine of boron trifluoride, triisopropylphosphine of boron trifluoride and trimethylphosphine;

[0020] The inorganic filler is one or a combination of two or more of fused silica, calcined kaolin, montmorillonite and sepiolite.

[0021] The present invention uses heat-resistant biphenyl epoxy resin and polymethyl silicone resin with low melt viscosity as the main resin, bisphenol A phenolic resin as the curing agent, and then matches with high-temperature resistant inorganic filler and high-silica glass fiber, so as to improve the heat resistance of the obtained epoxy molding compound while improving the strength retention rate. The test results of the applicant show that the test piece of the epoxy molding compound injection molded by the present invention still maintains sufficient strength after being heated to a high temperature of 1000°C and lasting for 5 minutes, wherein the impact strength retention rate can reach more than 45%, the bending strength retention rate can reach more than 30%, and the electrical strength retention rate is more than 40%, which can meet the use requirements of aviation connectors.

[0022] In the above technical solution, the selection of curing accelerator has a key influence on whether the molding material of the present invention can be injection molded. When imidazole curing accelerator (such as 2-methylimidazole, 1B 2 MZ (1-benzyl-2-methylimidazole), 2MZ-CM (1-cyanoethyl-2-methylimidazole), 2E4MZ-CN (1-cyanoethyl-2-ethyl-4-methylimidazole), C 11 Z-CN (1-cyanoethyl-2-undecyl imidazole), C 11 When Z-CNS (1-cyanoethyl-2-undecyl-trimellitic acid imidazolate), 2PZ-CNS (1-cyanoethyl-2-phenyltrimellitic acid imidazolate) or 2MZ-AZINE (2,4-diamino-6[-2-methylimidazolyl (1)]-ethyl-cis-triazine) or amine curing accelerators (such as 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), benzyldimethylamine (BDMA), triethylamine, triethanolamine, m-phenylenediamine or p-phenylenediamine, etc.) are added, the molding material will be more easily cured in the barrel of the injection machine.

[0023] In the above technical solution, the weight percentage of each component is preferably:

[0024] Epoxy resin 10-20%;

[0025] Polymethyl silicone resin 8-12%;

[0026] Curing agent 3.5-12%;

[0027] Curing accelerator 1.2-2%;

[0028] Inorganic filler 25-30%;

[0029] Release agent 1-1.5%;

[0030] High silica glass fiber 25-32%;

[0031] Flame retardant 5-8%;

[0032] Pigment 0~0.5%.

[0033] In the above technical scheme, the biphenyl epoxy resin can be any one of BPNE3501LL, BPNE3501L, BPNE3501M, BPNE3501H, BPNH9781S, JX9000H, SQXN322, SQXN322, SQXN323, SQXN324, NC3000LL, NC3000L, NC3000M, NC3000H, TT4000 and YX4000, or a combination of any two or more thereof.

[0034] In the above technical scheme, the release agent, flame retardant and pigment can be conventionally selected. Specifically, the release agent can be one or a combination of two or more selected from zinc stearate, calcium stearate, barium stearate, magnesium stearate, pentaerythritol stearate and palm wax. The flame retardant can be one or a combination of two or more selected from magnesium hydroxide, bismuth trioxide, aluminum oxide monohydrate, antimony oxide, antimony pentoxide and zinc borate. The pigment can be one or a combination of two or more selected from phthalocyanine blue, phthalocyanine green, iron red, permanent yellow, permanent purple and carbon black.

[0035] The method for preparing the high temperature resistant epoxy molding compound for aviation connectors of the present invention comprises the following steps:

[0036] (1) Weigh each component according to the recipe and set aside.

[0037] (2) placing the weighed epoxy resin, curing agent and release agent in a container, adding a mixed solution of acetone and ethanol, stirring and dissolving until a viscous state is obtained to obtain a mixed material A for standby use;

[0038] (3) kneading the mixture A with polymethyl silicone resin, curing accelerator, inorganic filler, flame retardant and pigment evenly through a kneader, and then adding high silica glass fiber and mixing evenly to obtain a mixture B;

[0039] (4) The obtained mixed material B is rolled into sheets after plastic refining and crushed to obtain the obtained product.

[0040] In step (2) of the above preparation method, the volume ratio of acetone and ethanol constituting the mixed solution is 1:1 to 3, preferably 1:3. In this step, when the amount of the mixed solution added is 1 to 2.5 times the sum of the weight of the epoxy resin, the curing agent and the release agent, the obtained material is viscous after being stirred and dissolved. It is further preferred that the amount of the mixed solution added is 1.5 to 2 times the sum of the weight of the epoxy resin, the curing agent and the release agent.

[0041] In step (4) of the above preparation method, the mixed material B is plasticized according to conventional techniques, specifically, it can be plasticized on an open mill, the plasticized material is rolled into sheets, and after cooling, it is crushed, sieved, and magnetically separated to obtain the high temperature resistant epoxy molding compound for aviation connectors.

[0042] The high temperature resistant epoxy molding compound for aviation connectors of the present invention is injection molded by a thermosetting injection molding machine. The injection molding conditions are preferably: mold temperature of 170-185°C, barrel temperature of 60-75°C, nozzle temperature of 70-85°C, injection pressure of 30-60MPa, and curing time of 90-120S.

[0043] Compared with the prior art, the present invention selects epoxy resin and polymethyl silicone resin with low viscosity as the main resin, bisphenol A phenolic resin as the curing agent, and then mixes them with high temperature resistant inorganic filler and high silica glass fiber in a specific proportion, and the obtained epoxy molding compound has excellent heat resistance. The test results of the applicant show that the test piece of the epoxy molding compound injection molded by the present invention still maintains sufficient strength after being heated to a high temperature of 1000°C and lasting for 5 minutes, wherein the impact strength retention rate can reach more than 45%, the bending strength retention rate can reach more than 30%, and the electrical strength retention rate is more than 40%, which can meet the use requirements of aviation connectors. DETAILED DESCRIPTION

[0044] In order to better explain the technical solution of the present invention, the present invention is further described in detail below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto.

[0045] Example 1

[0046] 1. Formula

[0047] Epoxy resin: biphenyl crystalline epoxy resin, 15%;

[0048] Polymethylsilicone: 5%;

[0049] Curing agent: bisphenol A phenolic resin YDBN602, 3.5%;

[0050] Curing accelerator: triphenylphosphine, 1.2%;

[0051] Inorganic filler: 39.2% (consisting of 54% calcined kaolin and 46% montmorillonite);

[0052] Release agent: 1.1% (consisting of 80% calcium stearate and 20% zinc stearate);

[0053] High silica glass fiber: 30%;

[0054] Flame retardant: magnesium hydroxide, 5%.

[0055] 2. Preparation method

[0056] (1) Weigh each component according to the recipe and set aside.

[0057] (2) placing the epoxy resin, curing agent and release agent in a container, adding a mixed liquid (composed of acetone and ethanol in a volume ratio of 1:1) equivalent to 1.5 times the sum of the weight of the epoxy resin, curing agent and release agent, stirring and dissolving until a viscous state is obtained to obtain a mixture A;

[0058] (3) placing mixed material A in a kneader, adding polymethyl silicone resin, curing accelerator, inorganic filler and flame retardant and mixing evenly, then adding high silica glass fiber and kneading thoroughly to obtain mixed material B;

[0059] (4) The obtained mixed material B is placed in an open mill for plasticizing, and after the solvent in the material is fully volatilized, it is rolled into sheets, and after cooling, it is crushed, sieved, and magnetically separated to obtain the high temperature resistant epoxy molding compound.

[0060] Comparative Example 1

[0061] 1. Formula

[0062] o-Cresol formaldehyde epoxy resin 25%, linear phenolic resin PF-8012 6.5%, 2-methylimidazole 1.5%, silica powder (400 mesh) 26.2%, calcium stearate 1.8%, short-cut glass fiber 30%, aluminum hydroxide 9%.

[0063] 2. Preparation method

[0064] Weigh each component according to the formula, mix them evenly, place the obtained mixture in an open mill for plasticizing, roll it into sheets after it is evenly plasticized, and then crush, sieve and magnetically separate it after cooling to obtain ordinary epoxy molding compound.

[0065] Comparative Example 2

[0066] 1. Formula

[0067] The difference from Example 1 is that linear phenolic resin PF-8012 is used instead of bisphenol A type phenolic resin YDBN602, and the other parts remain unchanged.

[0068] 2. Preparation method

[0069] Same as Example 1.

[0070] Comparative Example 3

[0071] 1. Formula

[0072] The difference from Example 1 is that the inorganic filler is composed of 54% of ordinary kaolin and 46% of montmorillonite, and the other components remain unchanged.

[0073] 2. Preparation method

[0074] Same as Example 1.

[0075] Comparative Example 4

[0076] 1. Formula

[0077] The difference from Example 1 is that the polymethyl silicone resin is omitted, the amount of biphenyl crystalline epoxy resin is increased to 20%, and the other contents remain unchanged.

[0078] 2. Preparation method

[0079] Same as Example 1.

[0080] Comparative Example 5

[0081] 1. Formula

[0082] The difference from Example 1 is that 2-methylimidazole is used to replace triphenylphosphine, and the other parts remain unchanged.

[0083] 2. Preparation method

[0084] Same as Example 1.

[0085] Comparative Example 6

[0086] 1. Formula

[0087] The difference from Example 1 is that p-phenylenediamine is used to replace triphenylphosphine, and the other parts remain unchanged.

[0088] 2. Preparation method

[0089] Same as Example 1.

[0090] Example 2

[0091] 1. Formula

[0092] Epoxy resin: biphenyl crystalline epoxy resin, 20%;

[0093] Polymethylsilicone: 10%;

[0094] Curing agent: bisphenol A phenolic resin YDBN602, 4.2%;

[0095] Curing accelerator: triphenylphosphine, 1.4%;

[0096] Inorganic filler: fused silica, 27.8%;

[0097] Release agent: 1.1% (consisting of 80% calcium stearate and 20% zinc stearate);

[0098] High silica glass fiber: 32%;

[0099] Flame retardant: magnesium hydroxide, 3.5%.

[0100] 2. Preparation method

[0101] Same as Example 1.

[0102] Example 3

[0103] 1. Formula

[0104] Epoxy resin: 20% (composed of 85% biphenyl crystalline epoxy resin and 15% biphenyl phenol self-flame retardant epoxy resin);

[0105] Polymethylsilicone: 7%;

[0106] Curing agent: bisphenol A phenolic resin YDBN602, 4.2%;

[0107] Curing accelerator: triphenylphosphine, 1.4%;

[0108] Inorganic filler: kaolin, 31.1%;

[0109] Release agent: 1.1% (composed of 70% calcium stearate and 30% magnesium stearate);

[0110] High silica glass fiber: 30%;

[0111] Flame retardant: magnesium hydroxide, 5.2%.

[0112] 2. Preparation method

[0113] Same as Example 1.

[0114] Example 4

[0115] 1. Formula

[0116] Epoxy resin: 20% (composed of 75% phenol biphenyl type epoxy resin and 25% biphenyl phenol type self-flame retardant epoxy resin);

[0117] Polymethylsilicone: 5%;

[0118] Curing agent: bisphenol A phenolic resin YDBN602, 10%;

[0119] Curing accelerator: triphenylphosphine, 1.4%;

[0120] Inorganic filler: sepiolite, 31.9%;

[0121] Release agent: 1.5% (composed of 70% zinc stearate and 30% zinc stearate);

[0122] High silica glass fiber: 25%;

[0123] Flame retardant: magnesium hydroxide, 5.2%.

[0124] 2. Preparation method

[0125] Same as Example 1.

[0126] Example 5

[0127] 1. Formula

[0128] Epoxy resin: 15% (composed of 70% biphenyl crystalline epoxy resin, 15% phenol biphenyl epoxy resin and 15% biphenyl phenol self-flame retardant epoxy resin);

[0129] Polymethylsilicone: 5%;

[0130] Curing agent: bisphenol A phenolic resin YDBN602, 4%;

[0131] Curing accelerator: trimethylphosphine, 1.3%;

[0132] Inorganic filler: montmorillonite, 33.4%;

[0133] Release agent: 1.3% (composed of 70% calcium stearate and 30% zinc stearate);

[0134] High silica glass fiber: 35%;

[0135] Flame retardant: bismuth trioxide, 5%.

[0136] 2. Preparation method

[0137] Same as Example 1.

[0138] Example 6

[0139] 1. Formula

[0140] Epoxy resin: biphenyl crystalline epoxy resin, 15%;

[0141] Polymethylsilicone: 12%;

[0142] Curing agent: bisphenol A phenolic resin YDBN602, 12%;

[0143] Curing accelerator: boron trifluoride triethylphosphine, 1.5%;

[0144] Inorganic filler: fused silica, 34.5%;

[0145] Release agent: palm wax, 1.4%;

[0146] High silica glass fiber: 20%;

[0147] Flame retardant: bismuth trioxide, 3.5%;

[0148] Pigment: Phthalocyanine blue, 0.1%.

[0149] 2. Preparation method

[0150] (1) Weigh each component according to the recipe and set aside.

[0151] (2) placing the epoxy resin, curing agent and release agent in a container, adding a mixed liquid (composed of acetone and ethanol in a volume ratio of 1:1.5) equivalent to twice the sum of the weight of the epoxy resin, the curing agent and the release agent, stirring and dissolving until a viscous state is obtained to obtain a mixture A;

[0152] (3) placing mixed material A in a kneader, adding polymethyl silicone resin, curing accelerator, inorganic filler, flame retardant and pigment and mixing them evenly, then adding high silica glass fiber and kneading them thoroughly to obtain mixed material B;

[0153] (4) The obtained mixed material B is placed in an open mill for mixing, and after the solvent in the material is fully volatilized, it is rolled into sheets, and after cooling, it is crushed, sieved, and magnetically separated to obtain the high temperature resistant epoxy molding compound.

[0154] The epoxy molding materials obtained in the above-mentioned Examples 1 to 6 and Comparative Examples 1 to 6 were respectively placed in the barrel of a thermosetting injection molding machine to form test pieces (the test piece corresponding to the unnotched impact strength test was a strip of 120*15*10mm, the test piece corresponding to the bending strength test was a strip of 120mm*10mm*4mm, and the test piece corresponding to the electrical strength test was a disc of 100mm*2mm). The injection molding conditions were: mold temperature of 170 to 185°C, barrel temperature of 60 to 75°C, nozzle temperature of 70 to 85°C, injection pressure of 30 to 60MPa, and curing time of 90 to 120s. The injection molded test pieces were subjected to performance tests, and the results are shown in Tables 1 and 2 below:

[0155] Table 1:

[0156]

[0157]

[0158] Table 2:

[0159]

[0160] For Comparative Examples 5 and 6, the epoxy molding materials solidified after being stored in the barrel of the injection machine for a period of time and could not be normally injection molded. Therefore, no test pieces were obtained and no relevant tests were performed.

[0161] It can be seen that the epoxy molding compound prepared by adopting the limited formula of the present invention has excellent unnotched impact strength, flexural strength and electrical strength, wherein the unnotched impact strength retention rate can reach more than 45%, the flexural strength retention rate can reach more than 30%, and the electrical strength retention rate is more than 40%, which can ensure the safety of the obtained molding compound for injection-molded aviation connector parts.

Claims

1. A high temperature resistant epoxy molding compound for aviation connectors, characterized in that: Made of the following components by weight percentage: Epoxy resin 10-25%; Polymethyl silicone resin 5-15%; Curing agent 3-15%; Curing accelerator 1.2-3%; Inorganic filler 20-40%; Release agent 0.8~1.5%; High silica glass fiber 20-35%; Flame retardant 3-10%; Pigment 0-1%; in, The epoxy resin is one or a combination of two or more selected from biphenyl crystalline epoxy resin, phenol biphenyl epoxy resin and biphenyl phenol self-flame retardant epoxy resin; The curing agent is bisphenol A phenolic resin; The curing accelerator is one or a combination of two or more selected from triphenylphosphine, tri(dimethylamino)phenylphosphine, triethylphosphine of boron trifluoride, triisopropylphosphine of boron trifluoride and trimethylphosphine; The inorganic filler is one or a combination of two or more of fused silica, calcined kaolin, montmorillonite and sepiolite.

2. The high temperature resistant epoxy molding compound for aviation connectors according to claim 1 is characterized in that: The weight percentage of each component is: Epoxy resin 10-20%; Polymethyl silicone resin 8-12%; Curing agent 3.5-12%; Curing accelerator 1.2-2%; Inorganic filler 25-35%; Release agent 1-1.5%; High silica glass fiber 25-32%; Flame retardant 5-8%; Pigment 0~0.5%.

3. The high temperature resistant epoxy molding compound for aviation connectors according to claim 1 or 2, characterized in that: The demoulding agent is one or a combination of two or more selected from zinc stearate, calcium stearate, barium stearate, magnesium stearate, pentaerythritol stearate and palm wax.

4. The high temperature resistant epoxy molding compound for aviation connectors according to claim 1 or 2, characterized in that: The flame retardant is one or a combination of two or more selected from magnesium hydroxide, bismuth trioxide, aluminum oxide monohydrate, antimony oxide, antimony pentoxide and zinc borate.

5. The high temperature resistant epoxy molding compound for aviation connectors according to claim 1 or 2, characterized in that: The pigment is one or a combination of two or more selected from phthalocyanine blue, phthalocyanine green, iron red, permanent yellow, permanent violet and carbon black.

6. The method for preparing the high temperature resistant epoxy molding compound for aviation connectors according to claim 1 comprises the following steps: (1) Weigh each component according to the recipe and set aside. (2) placing the weighed epoxy resin, curing agent and release agent in a container, adding a mixed solution of acetone and ethanol, stirring and dissolving until a viscous state is obtained to obtain a mixed material A for standby use; (3) Mixing the mixture A with polymethyl silicone resin, curing accelerator, inorganic filler, flame retardant and pigment, and then adding high silica glass fiber and mixing evenly to obtain a mixture B; (4) The obtained mixed material B is rolled into sheets after plastic refining and crushed to obtain the obtained product.

7. The preparation method according to claim 6, characterized in that: In step (2), the volume ratio of acetone to ethanol is 1:1-3.

8. The preparation method according to claim 6, characterized in that: In step (2), the amount of the mixed liquid is 1 to 2.5 times the sum of the weight of the epoxy resin, the curing agent and the release agent.

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