Epoxy resin material and preparation method thereof

Abstract

The present invention provides an epoxy resin material and a preparation method thereof. The epoxy resin material is prepared from the following raw materials in parts by weight: 63-82 parts of epoxy resin, 13-29 parts of curing agent, 1.8-4.3 parts of toughening agent, and 1.8-6 parts of reactive diluent. The epoxy resin is an epoxy resin having a benzene ring in the main chain, and the reactive diluent is an aliphatic chain segment containing a terminal amine group, wherein the aliphatic chain segment contains a furan ring or a benzene ring. The addition of the reactive diluent to the epoxy resin material prepared by the present invention not only reduces the viscosity of the epoxy resin system before the reaction, but also improves the modulus and toughness of the epoxy resin material obtained after curing, and increases the gel time of the epoxy system.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to an epoxy resin material with high modulus, low viscosity and long gel time and a preparation method thereof. Background Art

[0002] Epoxy resin systems in the prior art generally suffer from low toughness, high viscosity, and low modulus. Chinese patent application CN 109422867 B discloses a high-modulus, low-viscosity epoxy resin. This resin is prepared by adding a suitable amount of a low-viscosity, single-terminated fatty amine to a low-viscosity epoxy resin component. This component is then mixed with a curing agent and subjected to a curing reaction to produce an epoxy resin cured product with high tensile strength, high tensile modulus, and good toughness. However, while this reduces the viscosity of the epoxy resin, the resulting epoxy resin exhibits a short gel time, with the operating time generally considered to be 75% of the gel time, resulting in reduced operability. Summary of the Invention

[0003] In order to overcome the technical problem in the prior art that it is impossible to simultaneously reduce the viscosity and take into account the modulus, toughness and gel time of the epoxy resin, the present invention provides an epoxy resin material and a preparation method thereof. By using a terminal amino fatty chain segment compound with a furan ring or a benzene ring as a reactive diluent, not only can the viscosity of the epoxy resin system be reduced before the reaction, but the epoxy resin material obtained after curing also has improved modulus and toughness, and increased gel time of the epoxy system.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0005] A first aspect of the present invention provides an epoxy resin material, which is prepared from the following raw materials in parts by weight:

[0006]

[0007] The epoxy resin is an epoxy resin with a benzene ring in the main chain, and the reactive diluent is a fatty chain segment containing a terminal amine group, wherein the fatty chain segment contains a furan ring or a benzene ring.

[0008] The present invention reduces the viscosity of the epoxy resin system before the reaction by adding a terminal amine-containing fatty chain segment compound with a furan ring or a benzene ring as a reactive diluent. By adding a very small amount of a toughening agent to the epoxy resin system, the toughening agent does not participate in the chemical reaction, thereby improving strength and toughness while ensuring a complete cross-linked network. During the curing process, the reactive diluent participates in the reaction, combining with the resin system to provide some performance benefits. After curing, the benzene rings on the main chain and the fatty chain segments on the side chains repel each other, causing the side chains to aggregate and form a microphase separation structure, which can improve the modulus and toughness of the epoxy resin material.

[0009] Since the aliphatic chain contains furan rings or benzene rings, it provides modulus for the epoxy resin system while reducing the reaction rate, that is, increasing the gel time. It is generally believed in the art that 75% of the gel time is the operating time, so the operating time is increased.

[0010] As an optional embodiment, in the epoxy resin material provided by the present invention, the active diluent is one or more of 2-aminoethylfuran, 3-(2-furyl)-1-methylpropylamine, (3,5-dimethyl-4-isoxazole)acetic acid, N-[3-(2-furyl)-1-methylpropyl]-n-methylamine, 3-phenyl-1-propylamine, 1-phenyl-2ethylbutylamine, 2-methyl-4-phenylbutylamine and 6-phenylhexylamine.

[0011] As an optional embodiment, in the epoxy resin material provided by the present invention, the curing agent is one or more of menthane diamine, isophorone diamine, bis(4-amino-3-methylcyclohexyl)methane, 4,4'-diaminodicyclohexylmethane, bis(4-aminocyclohexyl)methane, 4,4'-diaminodiphenylmethane, diaminodiphenyl sulfone and m-phenylenediamine.

[0012] As an optional embodiment, in the epoxy resin material provided by the present invention, the toughening agent is one or more of cardanol, N-diglycidyl aniline and nitrile rubber.

[0013] As an optional embodiment, in the epoxy resin material provided by the present invention, the epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned epoxy resin material, comprising the following steps:

[0015] S1. Mix the epoxy resin and the reactive diluent, and heat and stir until uniform;

[0016] S2, adding a curing agent and a toughening agent to the mixture after step S1, stirring evenly, and vacuuming to remove bubbles;

[0017] S3, pouring and curing the material after step S2 to obtain epoxy resin material.

[0018] In this application, the reaction is of small molecule amines, so the heat release is relatively fast in the early stage. Directly increasing the temperature will lead to violent heat release, increased thermal stress, and reduced performance. Therefore, a staged heating method is adopted. First, the reaction is carried out at a low temperature for a period of time to allow the more active small molecule amines (active diluents) and curing agents to partially react, and finally the temperature is increased to ensure the complete reaction.

[0019] As an optional embodiment, in the preparation method provided by the present invention, the curing in step S3 adopts segmented heating, curing at 80-100° C. for 2-3 hours and then curing at 130-150° C. for 3-5 hours.

[0020] As an optional embodiment, in the preparation method provided by the present invention, step S1 and step S2 are heated in a constant temperature oil bath, and the temperature of the oil bath is 50-70°C.

[0021] The reaction mechanism of this invention is as follows: the numerous benzene ring structures in the epoxy resin backbone and the fatty side chains of the introduced reactive diluent repel each other due to their different rigidity and flexibility, causing the side chains to aggregate and form a microphase-separated structure. This structure compacts the epoxy network, reduces free volume, and thus increases modulus. After stretching, the microphase-separated structure disappears, leaving flexible side chains in the system, improving toughness.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention provides an epoxy resin, which uses a terminal amino fatty chain segment compound with a furan ring or a benzene ring as an active diluent to reduce the viscosity of the resin system before the reaction, participate in the reaction during the curing process, and combine with the epoxy resin system to improve the modulus of the epoxy resin material, reduce the reaction speed, and increase the gel time.

[0024] (2) The epoxy resin material prepared by the present invention has a tensile strength of 89 to 95 MPa, a tensile film capacity of 3.54 to 3.66 GPa, an elongation at break of more than 6.78, a viscosity of the system at 25°C of less than 304 mPa·s, and a gel time increased to more than 84 min. DETAILED DESCRIPTION

[0025] To facilitate understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0027] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0028] Example 1:

[0029] Mix 80g of bisphenol A epoxy resin and 3g of 2-aminoethylfuran in a beaker and place it in a constant temperature oil bath at 50℃ and stir at medium speed for 10min. Add 28g of menthane diamine and 2.1g of cardanol and mix them in a beaker and place it in a constant temperature oil bath at 50℃ and stir at medium speed for 10s. Vacuum to remove bubbles, and pour and cure at 90℃ / 3h+140℃ / 4h to obtain epoxy resin cured product.

[0030] Example 2

[0031] Mix 75g of bisphenol F epoxy resin and 4g of 3-phenyl-1-propylamine in a beaker and place it in a constant temperature oil bath at 60℃ and stir at medium speed for 10min. Add 26g of 4,4'-diaminodicyclohexylmethane and 1.83g of cardanol, mix them in a beaker and place it in a constant temperature oil bath at 60℃ and stir at medium speed for 10s. Vacuum to remove bubbles, and pour and cure at 80℃ / 2h+140℃ / 5h to obtain epoxy resin cured product.

[0032] Example 3

[0033] Mix 65 g of bisphenol F epoxy resin and 2 g of 1-phenyl-2-ethylbutylamine in a beaker and place in a constant temperature oil bath at 60°C and stir at medium speed for 10 min. Add 17 g of bis(4-amino-3-methylcyclohexyl)methane and 2.8 g of N-diglycidylaniline, mix in a beaker and place in a constant temperature oil bath at 60°C and stir at medium speed for 10 s. Vacuum to remove bubbles, and pour and cure at 80°C / 2 h + 130°C / 5 h to obtain an epoxy resin cured product.

[0034] Example 4

[0035] 75 g of tetrafunctional epoxy resin and 1.9 g of 2-methyl-4-phenylbutylamine were mixed in a beaker and placed in a constant temperature oil bath at 70°C and stirred at medium speed for 10 min. 14 g of isophorone diamine and 2.4 g of N-diglycidyl aniline were added and mixed in a beaker and placed in a constant temperature oil bath at 70°C and stirred at medium speed for 10 s. Vacuum to remove bubbles, and pour and cure at 100°C / 3 h + 130°C / 5 h to obtain an epoxy resin cured product.

[0036] Example 5

[0037] Mix 80 g of bisphenol A epoxy resin and 3 g of 6-phenylhexylamine in a beaker and place in a 70°C constant temperature oil bath, stirring at medium speed for 10 min. Add 21 g of 4,4'-diaminodiphenylmethane and 4 g of N-diglycidylaniline, mix in a beaker, place in a 70°C constant temperature oil bath, stirring at medium speed for 10 s, vacuum to remove bubbles, and pour and cure at 80°C / 3 h + 140°C / 5 h to obtain epoxy resin cured product.

[0038] Comparative Example 1

[0039] Chinese invention patent application CN201710791019.6 discloses a high modulus, low viscosity epoxy resin prepared using a single-ended fatty amine as a reactive diluent and an amine compound as a curing agent.

[0040] Comparative Example 2

[0041] Mix 100g of bisphenol F epoxy resin and 40g of 4,4'-diaminodiphenylmethane in a beaker, place in a constant temperature oil bath, and stir for 10 minutes. Vacuum to remove bubbles, and pour and cure at 80℃ / 2h + 150℃ / 5h to obtain epoxy resin cured product.

[0042] Performance testing

[0043] The mechanical properties, viscosity, and gel time of the epoxy resin cured products prepared in Examples 1-5 and Comparative Examples 1-2 were tested. The test results are shown in Table 1 below:

[0044] Table 1: Test results of epoxy resin cured products

[0045]

[0046] As shown in Table 1, compared with Comparative Example 2, a pure resin system, the epoxy resin materials prepared in Examples 1-5 exhibited increased tensile modulus and break length, significantly reduced system viscosity, and increased gel time, thereby extending operability. Compared with Comparative Example 1, which used a single-terminal fatty amine as a reactive diluent, the epoxy resin materials prepared in Examples 1-5 further reduced the viscosity of the epoxy system without compromising mechanical properties, and in some cases even improved them. Furthermore, they significantly increased gel time and enhanced operability.

[0047] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. An epoxy resin material, characterized in that: The epoxy resin material is prepared from the following raw materials in parts by weight: 63-82 parts of epoxy resin, 13-29 parts of curing agent, 1.8-4.3 parts of toughening agent, 1.8-6 parts of reactive diluent; The epoxy resin is an epoxy resin with a benzene ring in the main chain, and the reactive diluent is a fatty chain segment containing a terminal amine group, wherein the fatty chain segment contains a furan ring; The active diluent is one or more of 2-aminoethylfuran and 3-(2-furyl)-1-methylpropylamine.

2. The epoxy resin material according to claim 1, characterized in that The curing agent is one or more of menthane diamine, isophorone diamine, bis(4-amino-3-methylcyclohexyl)methane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, diaminodiphenyl sulfone and m-phenylenediamine.

3. The epoxy resin material according to claim 1, characterized in that The toughening agent is one or more of cardanol, N-diglycidyl aniline and nitrile rubber.

4. The epoxy resin material according to claim 1, characterized in that The epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

5. The method for preparing the epoxy resin material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Mix the epoxy resin and the reactive diluent, and heat and stir until uniform; S2, adding a curing agent and a toughening agent to the mixture after step S1, stirring evenly, and vacuuming to remove bubbles; S3, pouring and curing the material after step S2 to obtain epoxy resin material.

6. The method for preparing the epoxy resin material according to claim 5, wherein: The curing in step S3 is performed by segmented heating, curing at 80-100° C. for 2-3 hours and then curing at 130-150° C. for 3-5 hours.

7. The method for preparing the epoxy resin material according to claim 5, wherein: Step S1 and step S2 are heated in a constant temperature oil bath, and the temperature of the oil bath is 50-70°C.

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