High-performance cured epoxy resin as well as preparation method and application thereof

Abstract

The invention discloses a high-performance epoxy resin cured product, a preparation method thereof and application of the high-performance epoxy resin cured product in manufacturing optical devices. The high-performance cured epoxy resin is obtained by curing the following raw material components in parts by mass: 100 parts of epoxy resin; and 8.0 to 39.0 parts of a 1, 4-cyclohexane diamine curing agent. The preparation method comprises the following steps: respectively dehydrating the epoxy resin and the 1, 4-cyclohexane diamine curing agent, uniformly mixing, defoaming and curing to obtain the high-performance cured epoxy resin. The cured epoxy resin provided by the invention has high Tg, excellent ultraviolet aging resistance, heat resistance, light and color retention, mechanical properties and high transparency, and is very suitable for being used in the field of optical devices such as LED packaging materials and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resins, and particularly relates to a high-performance epoxy resin cured product, a preparation method thereof and an application thereof. Background Art

[0002] Semiconductor lighting is one of the most promising high-tech fields in the 21st century. Light-emitting diodes (LEDs) are efficient solid light sources, which have the advantages of long life, energy conservation and environmental protection. An LED is composed of a chip, a wire, a bracket, a conductive adhesive, a packaging material, etc. Its packaging is to pour a liquid adhesive into a device containing electronic components and circuits by means of filling, potting or molding. The LED packaging material can strengthen the integrity of the electronic device, improve the resistance to external impact and vibration, improve the insulation between the internal components and circuits of the LED, and avoid the direct exposure of the components and circuits. Therefore, it has an important impact on the reliability and lighting effect of the LED.

[0003] At present, the main LED packaging materials are highly transparent materials such as epoxy resins, polycarbonates, polymethyl methacrylates, glass, and silicone. Considering factors such as cost and electrical properties, epoxy resins are still the mainstream of packaging materials. The epoxy resins used in LED packaging are required to have high light transmittance, good heat resistance, ultraviolet aging resistance, excellent mechanical properties, etc. The epoxy resin cured product prepared by combining ordinary epoxy resin and a curing agent is prone to aging and has poor heat resistance, and obviously it is difficult to meet the above requirements. Therefore, modified epoxy resin packaging materials have emerged. The modification directions of epoxy resins mainly include improving light stability and heat resistance. Improving light stability mainly refers to improving the ability of epoxy resin to resist ultraviolet light aging. The main method for improving light stability is to add a light stabilizer to the epoxy resin, and the light stabilizer is an inorganic or organic ultraviolet absorber.

[0004] In "Modification of Transparent Epoxy Resin for LED Packaging", Li Yuanqing et al. selected o-hydroxybenzophenone, benzotriazole, hindered amine, etc. as light stabilizers to modify the transparent epoxy resin EP-400 for LED packaging, and studied the effects of light stabilizers on the light transmittance and ultraviolet aging resistance of epoxy resins.

[0005] Improving the heat resistance of epoxy resin packaging materials mainly refers to increasing its glass transition temperature (Tg). The commonly used modification methods are usually to blend heat-resistant resins, such as phenolic epoxy resins, polyfunctional epoxy resins, etc.; selecting a suitable curing agent is also beneficial to increasing the Tg of the material. Modifying epoxy resin with silicone can also improve the heat resistance of packaging materials.

[0006] In the research of "Study on Hyperbranched Polyester Modified Epoxy Resin for LED Encapsulation", Zeng Qingpeng used hyperbranched polyesters with terminal hydroxyl groups H20, H30 and hyperbranched polyester H20-COOH modified with terminal carboxyl groups and anhydride curing agents to prepare cured products of o-cresol novolac epoxy resin, and investigated the effects of their contents on the light transmittance, heat resistance, etc. of the epoxy resin. The highest glass transition temperature of the prepared epoxy resin cured product was 172.8 °C, and the light transmittance was all lower than 85%.

[0007] Polymers containing fluorene ring structures have a series of excellent properties such as high heat resistance, high transparency, high refractive index and low linear expansion coefficient. In the research of "Preparation and Thermal Properties of Bisphenol Fluorene Epoxy Resin Monomer with Crystal Structure", Liu Hanping introduced bisphenol fluorene into epoxy resin to prepare high-purity bisphenol fluorene epoxy resin (DGEBF) with single crystal structure, and then prepared a long-chain flexible curing agent through the addition reaction of 4,4-diaminodiphenyl sulfone (DDS) and bismaleimide (BMI). The cured product of epoxy resin was prepared by curing this curing agent with bisphenol fluorene epoxy resin (DGEBF). The glass transition temperature of this cured product was 264 °C. The light transmittance was not tested in this literature. The curing agent molecule structure contains benzene rings, and its ultraviolet aging resistance is poor, and the preparation process is complex and the cost is too high.

[0008] In the research of "Light-colored Transparent Epoxy Resin CGY-331", Chenguang Research Institute of Chemical Industry developed a light-colored transparent epoxy resin CGY-331. The cured product prepared from this epoxy resin and p-phenylenediamine had high light transmittance and was close to colorless and transparent, but the highest glass transition temperature was only 109 °C.

[0009] The patent specification with the publication number CN114729105A discloses a curable resin composition, a method for producing a cured composition using the curable resin composition, and an article produced by this method, especially a molded article. The resin composition disclosed in this invention contains at least one epoxy resin component, at least one curing component and at least one phosphonium compound. By using a phosphonium compound instead of a tertiary amine as the curing catalyst in the epoxy resin-anhydride system, a curable formulation with both a high glass transition temperature and excellent optical properties (i.e., reduced yellowing and improved transparency) in the cured state can be obtained.

[0010] In summary, to prepare an epoxy resin cured product with excellent ultraviolet aging resistance, light and color retention performance, mechanical properties and high transparency, it is still necessary to achieve it by means of adding special additives, special epoxy resins, etc. Summary of the Invention

[0011] In view of the above technical problems and the deficiencies in this field, the present invention provides a high-performance epoxy resin cured product, its preparation method and application.

[0012] Through a large number of experimental screenings, the present invention can prepare a high-performance epoxy resin cured product by using a special amine curing agent and a commercial general epoxy resin. The epoxy resin cured product has a high Tg and also has excellent ultraviolet aging resistance, heat resistance, light and color retention performance, mechanical properties (high tensile strength and high impact strength), and high transparency (light transmittance), and is very suitable for use in optical device fields such as LED packaging materials.

[0013] The specific technical solution is as follows:

[0014] [1] A high-performance epoxy resin cured product is obtained by curing raw material components containing the following parts by mass: 100 parts of epoxy resin; 8.0 - 39.0 parts of 1,4-cyclohexanediamine curing agent, such as 13.14 parts, 14.60 parts, 15.33 parts, 16.06 parts, etc., preferably 14.0 - 33.5 parts, and further preferably 16.0 - 28.3 parts.

[0015] In some preferred examples, in the raw material components of the high-performance epoxy resin cured product of the present invention, the 1,4-cyclohexanediamine curing agent and the epoxy resin can be added according to the molar equivalent ratio of amine group and epoxy group chemical reaction of 1 - 1.1:1 (such as 1.05:1, etc.).

[0016] The content of trans-1,4-cyclohexanediamine in the 1,4-cyclohexanediamine can be 0 - 100%, such as 0.001%, 0.01%, 0.1%, 1%, 5%, 10%, 20%, 40%, 60%, 80%, 100%, etc., and further can be 20% - 100%. A high content of trans-1,4-cyclohexanediamine in the 1,4-cyclohexanediamine is beneficial to improving the Tg, transparency (light transmittance), mechanical properties (including tensile strength and impact strength), heat resistance, ultraviolet aging resistance, and light and color retention performance of the obtained epoxy resin cured product.

[0017] The present invention does not have special requirements for the epoxy resin raw material. For example, the epoxy resin can include one or more of glycidyl ether epoxy resins, glycidyl amine epoxy resins, glycidyl ester epoxy resins, phenolic epoxy resins, aliphatic epoxy resins, etc., such as E51 epoxy resin.

[0018] The glass transition temperature of the high-performance epoxy resin cured product of the present invention is not less than 160 °C, further can be greater than 165 °C, and further still can be not less than 193 °C, and the light transmittance at 300 - 800 nm under a thickness of 1 mm is not less than 98%, and further can be not less than 99%.

[0019] [2]The preparation method of the high-performance epoxy resin cured product according to [1] includes: dehydrating epoxy resin and 1,4-cyclohexanediamine curing agent respectively, mixing them evenly, degassing, and curing to obtain the high-performance epoxy resin cured product.

[0020] The temperature of the curing can be 50 - 180 °C.

[0021] The time of the curing can be 2.5 - 80 h.

[0022] In some embodiments, the curing can be divided into two stages. Among them, the curing temperature in the first stage can be 50 - 109 °C (such as 80 °C, etc.), the curing time can be 2 - 30 h (such as 8 h, etc.), the curing temperature in the second stage can be 110 - 180 °C (such as 130 °C, etc.), and the curing time can be 0.5 - 20 h (such as 4 h, etc.).

[0023] In some embodiments, the curing can be divided into three stages. Among them, the curing temperature in the first stage can be 50 - 90 °C (such as 80 °C, etc.), the curing time can be 2 - 30 h (such as 8 h, etc.), the curing temperature in the second stage can be 95 - 120 °C (such as 110 °C, etc.), the curing time can be 2 - 30 h, and the curing temperature in the third stage can be 125 - 180 °C (such as 130 °C, etc.), and the curing time can be 0.5 - 20 h (such as 2 h, etc.).

[0024] [3]The application of the high-performance epoxy resin cured product according to [1] in manufacturing optical devices. For example, the high-performance epoxy resin cured product can be used to manufacture LED packaging materials.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The high-performance epoxy resin cured product involved in the present invention uses special 1,4-cyclohexanediamine as the curing agent. There are no unsaturated bonds in the molecular structure of 1,4-cyclohexanediamine, and the epoxy resin cured product prepared therefrom has excellent ultraviolet aging resistance and light and color retention performance.

[0027] 2. The high-performance epoxy resin cured product involved in the present invention uses 1,4-cyclohexanediamine as the curing agent. 1,4-cyclohexanediamine is the cycloaliphatic amine with the lowest molecular weight and has a high amine value. An epoxy resin cured product with excellent mechanical properties and heat resistance can be prepared with a very low dosage of amine curing agent.

[0028] 3. The high-performance epoxy resin cured product involved in the present invention preferably uses trans-1,4-cyclohexanediamine as the curing agent. Without any further modification, the glass transition temperature of the epoxy resin cured product prepared from trans-1,4-cyclohexanediamine with excellent symmetry and a commercially available general epoxy resin can exceed 190°C. This epoxy resin cured product simultaneously has excellent heat resistance, ultraviolet aging resistance, light and color retention performance, mechanical properties, and high transparency, and is very suitable for use in the field of optical devices. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0030] For the operation methods without specific conditions noted in the following examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0031] Unless otherwise specified, the raw materials, reagents, etc. used in each example can be obtained through commercial channels or existing technologies.

[0032] Example 1:

[0033] 100 g of E51 epoxy resin with an epoxy value of 0.511 and 16.06 g of 1,4-cyclohexanediamine with 0% trans-1,4-cyclohexanediamine content were dehydrated respectively. After being mixed evenly under stirring, the mixture was degassed. The epoxy resin and curing agent mixture was cured at high temperature. The curing stage was divided into 3 stages, including low-temperature curing, medium-temperature curing, and high-temperature curing. The low-temperature curing stage was curing at 80°C for 8 h, the medium-temperature curing stage was curing at 110°C for 2 h, and the high-temperature curing stage was curing at 130°C for 2 h to obtain an epoxy resin cured product, and the performance is shown in Table 1.

[0034] Example 2:

[0035] The difference from Example 1 was only that the trans-1,4-cyclohexanediamine content in 1,4-cyclohexanediamine was 20%, and the rest were the same, to obtain an epoxy resin cured product, and the performance is shown in Table 1.

[0036] Example 3:

[0037] The difference from Example 1 was only that the trans-1,4-cyclohexanediamine content in 1,4-cyclohexanediamine was 40%, and the rest were the same, to obtain an epoxy resin cured product, and the performance is shown in Table 1.

[0038] Example 4:

[0039] The difference from Example 1 was only that the trans-1,4-cyclohexanediamine content in 1,4-cyclohexanediamine was 60%, and the rest were the same, to obtain an epoxy resin cured product, and the performance is shown in Table 1.

[0040] Example 5:

[0041] The difference from Example 1 is only that the content of trans-1,4-cyclohexanediamine in 1,4-cyclohexanediamine is 80%, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0042] Example 6:

[0043] The difference from Example 1 is only that the content of trans-1,4-cyclohexanediamine in 1,4-cyclohexanediamine is 100%, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0044] Example 7:

[0045] The difference from Example 6 is only that the curing stage is divided into two stages, including low-temperature curing and high-temperature curing. The low-temperature curing stage is curing at 80 °C for 8 h, and the high-temperature curing stage is curing at 130 °C for 4 h. The rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0046] Example 8:

[0047] The difference from Example 4 is that the addition amount of 1,4-cyclohexanediamine is 14.60 g, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0048] Example 9:

[0049] The difference from Example 4 is that the addition amount of 1,4-cyclohexanediamine is 15.33 g, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0050] Comparative Example 1:

[0051] The difference from Example 1 is only that 1,4-cyclohexanediamine is not used, and instead 16.34 g of hexamethylenediamine is used as the curing agent, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0052] Comparative Example 2:

[0053] The difference from Example 1 is only that 1,4-cyclohexanediamine is not used, and instead 23.94 g of isophorone diamine is used as the curing agent, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0054] Comparative Example 3:

[0055] The difference from Example 1 is only that 1,4-cyclohexanediamine is not used, and instead 19.15 g of m-xylenediamine is used as the curing agent, and the rest are the same. An epoxy resin cured product is prepared, and the performance is shown in Table 1.

[0056] Comparative Example 4:

[0057] 100 g of E51 epoxy resin with an epoxy value of 0.511, 23.94 g of isophorone diamine curing agent, and 15 g of carbon fiber additive were dehydrated respectively. After being mixed evenly under stirring, the mixture was degassed. The epoxy resin, curing agent, and additive mixture was cured at high temperature. The curing stage was divided into 3 stages, including low-temperature curing, medium-temperature curing, and high-temperature curing. The low-temperature curing stage was curing at 80 °C for 8 h, the medium-temperature curing stage was curing at 110 °C for 2 h, and the high-temperature curing stage was curing at 130 °C for 2 h, obtaining an epoxy resin cured product, and the performance is shown in Table 1.

[0058] Comparative Example 5:

[0059] The difference from Example 1 was only that 1,4-cyclohexanediamine was not used, and instead 16.06 g of 1,2-cyclohexanediamine was used as the curing agent, and the rest were the same, obtaining an epoxy resin cured product, and the performance is shown in Table 1.

[0060] Table 1

[0061]

[0062] The glass transition temperature (Tg) was measured by differential scanning calorimetry (DSC). The thermal behavior of the sample in a nitrogen atmosphere was studied using a Mettler DSC1 differential scanning calorimeter. The sample mass was 3 - 5 mg, the nitrogen flow rate was set at 50 mL / min, and the test procedure for the sample was as follows: The sample was heated from 0 °C to 250 °C at a rate of 20 °C / min, held at a constant temperature for 2 min to eliminate the thermal history; then cooled to 0 °C at a rate of 20 °C / min to obtain a cooling curve, held at a constant temperature for 2 min, heated from 0 °C to 250 °C at a rate of 20 °C / min to obtain a heating curve, and finally cooled to room temperature at a rate of 20 °C / min.

[0063] The light transmittance was measured by UV-Vis ultraviolet spectrophotometry. The thickness of the test sample was 1 mm, and the wavelength test range was 300 - 800 nm.

[0064] For the tensile property test, according to GB / T 2567-2021, a MTS E43.104E type electronic universal testing machine was used for the test. The test environment was room temperature, and the displacement speed was set at 10 mm / min.

[0065] For the impact property test, according to GB / T 2567-2021, a Gotech digital testing machine was used for the test. The test environment was room temperature, the specimen was a type II specimen, and the span was 60 mm.

[0066] △E 1It is the change value of color difference of the sample before and after heat treatment in an oven at 100 °C for 7 days (d).

[0067] △E 2 It is the change value of color difference of the sample before and after heat treatment in an oven at 120 °C for 7 d.

[0068] △E 3 It is the change value of color difference of the sample before and after treatment in a xenon lamp aging chamber for 7 d.

[0069] Xenon lamp aging experiment: The xenon lamp aging experiment was carried out according to GB / T 16422.2-2022, with an irradiance of 0.51 W / (m 2 ·nm) (narrow band 340 nm), a black standard temperature of 65 °C, a test chamber temperature of 38 °C, a humidity of 50% RH, and an alternating cycle of 102 min of drying and 18 min of spraying.

[0070] Comparing Comparative Example 1 with the Examples, the test results show that the epoxy resin cured product prepared from hexamethylenediamine and E51 epoxy resin has a glass transition temperature of only 120 °C, and its mechanical properties such as tensile strength and impact strength are poor, and its heat resistance, ultraviolet aging resistance and light and color retention properties are all poor.

[0071] Comparing Comparative Example 2 with the Examples, the test results show that the epoxy resin cured product prepared from isophorone diamine and E51 epoxy resin has good comprehensive properties, but the glass transition temperature of the cured product is 162 °C.

[0072] Comparing Comparative Example 3 with the Examples, the test results show that the epoxy resin cured product prepared from m-xylenediamine and E51 epoxy resin has a glass transition temperature of only 128 °C, and its mechanical properties such as tensile strength and impact strength are excellent. Due to the benzene ring in the structure of m-xylenediamine, the epoxy resin cured product prepared from m-xylenediamine and E51 epoxy resin has poor ultraviolet aging resistance, and △E 3 is as high as 31.2.

[0073] Comparing Comparative Example 4 with the Examples and Comparative Example 2, the test results show that adding carbon fiber to the epoxy resin cured product prepared from isophorone diamine and E51 epoxy resin can increase the glass transition temperature of the cured product, but the light transmittance of the cured product is severely deteriorated and it cannot be used for LED packaging materials, etc.

[0074] Comparative Example 5 was compared with the examples. The test results showed that the epoxy resin cured product prepared from 1,2-cyclohexanediamine and E51 epoxy resin had a glass transition temperature of 171 °C, a transmittance of 99%, and excellent ultraviolet aging and heat aging resistance. However, the mechanical properties such as tensile strength and impact strength of this cured product were very poor. This was due to the difference in the properties of the cured product caused by the structural difference between 1,2-cyclohexanediamine and 1,4-cyclohexanediamine. The epoxy resin cured product prepared from 1,2-cyclohexanediamine could not be used in LED packaging materials, etc.

[0075] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A high performance epoxy resin cured product, characterized in that: The invention is obtained by curing the raw material components including the following parts by mass: 100 parts of epoxy resin; 8.0-39.0 parts of 1,4-cyclohexanediamine curing agent, preferably 14.0-33.5 parts, and more preferably 16.0-28.3 parts.

2. The high performance epoxy resin cured product according to claim 1, characterized in that: The content of trans-1,4-cyclohexanediamine in the 1,4-cyclohexanediamine is 0-100%, and further 20%-100%.

3. The high performance epoxy resin cured product according to claim 1, characterized in that: The epoxy resin includes one or more of glycidyl ether epoxy resin, glycidyl amine epoxy resin, glycidyl ester epoxy resin, phenolic epoxy resin, and aliphatic epoxy resin.

4. The high performance epoxy resin cured product according to any one of claims 1 to 3, characterized in that: The glass transition temperature of the high-performance epoxy resin cured product is not less than 160° C., further greater than 165° C., further not less than 193° C., and the light transmittance at 300-800 nm at a thickness of 1 mm is not less than 98%, further not less than 99%.

5. The method for preparing a high-performance epoxy resin cured product according to any one of claims 1 to 4, characterized in that: include: The epoxy resin and the 1,4-cyclohexanediamine curing agent are dehydrated respectively, mixed, degassed and cured to obtain the high-performance epoxy resin cured product.

6. The method for preparing a high-performance epoxy resin cured product according to claim 5, characterized in that: The curing temperature is 50-180° C., and the curing time is 2.5-80 hours.

7. The method for preparing a high-performance epoxy resin cured product according to claim 5 or 6, characterized in that: The curing is divided into two stages, wherein the curing temperature of the first stage is 50-109° C., the curing time is 2-30 hours, and the curing temperature of the second stage is 110-180° C., the curing time is 0.5-20 hours.

8. The method for preparing a high-performance epoxy resin cured product according to claim 5 or 6, characterized in that: The curing is divided into three stages, wherein the curing temperature of the first stage is 50-90°C, the curing time is 2-30h, the curing temperature of the second stage is 95-120°C, the curing time is 2-30h, and the curing temperature of the third stage is 125-180°C, the curing time is 0.5-20h.

9. Use of the high performance epoxy resin cured product according to any one of claims 1 to 4 in making optical devices.

10. The use according to claim 9, characterized in that: The high-performance epoxy resin cured product is used to prepare LED packaging materials.

Images