Process for the preparation of an epoxy elastomer having super flexibility

Abstract

The present invention discloses a method for preparing an epoxy elastomer with super flexibility, and the method uses a two-step process to complete the synthesis of the epoxy elastomer. The present invention realizes the transition from stable chemical crosslinking to flexible physical crosslinking in the epoxy system through the hydrolysis and metal ion coordination of the epoxy system, and introduces reversible metal ion-carboxyl dynamic coordination into the crosslinked epoxy network through the conversion between chemical crosslinking and physical crosslinking, so as to realize the construction of a dynamic crosslinking network in traditional epoxy resin, and the dynamic crosslinking network and the long flexible chain segment give the epoxy system excellent tensile properties. In addition, the introduction of the long flexible chain segment increases the free volume of the molecular chain in the epoxy system, reduces the Tg of the epoxy system, and converts the traditional brittle epoxy system into a flexible epoxy system, providing a simple and effective strategy for the construction of a flexible epoxy resin system.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of an epoxy elastomer, and in particular to a preparation method of an epoxy elastomer with super flexibility. BACKGROUND

[0002] Epoxy resin is a resin material with strong adhesion, excellent chemical resistance, mechanical and electrical properties, and thermal stability, and is widely used in the fields of automobile manufacturing, aerospace and marine engineering. Epoxy resins with different curing agents can be used to build resin systems with different properties. However, due to the low molecular weight and high rigidity of the molecular structure of epoxy resin, and the high crosslinking density after curing, epoxy resin materials often have problems such as high modulus, low flexibility, and high brittleness. Therefore, although the adhesive based on epoxy resin generally has high bonding strength, it has problems such as low tensile shear strain and high brittleness, and cannot adapt to application scenarios such as flexible adhesive, automobile impact-resistant parts, power battery impact-resistant adhesive, and heterojunction surface bonding adhesive. At the same time, for traditional epoxy resin systems, chemical crosslinking is often used, and the inherent properties of chemical crosslinking cannot endow the resin system with energy dissipation ability, making it difficult to prepare an epoxy resin system with high elasticity. So far, the construction and application of flexible epoxy resin systems are still a challenging problem.

[0003] Therefore, it is necessary to develop an epoxy elastomer with high flexibility to meet the diversified needs of flexible materials and broaden the application of traditional resin materials in emerging fields. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a preparation method of an epoxy elastomer with super flexibility. The present application realizes the transformation from stable chemical crosslinking to flexible physical crosslinking in the epoxy system through hydrolysis and metal ion coordination of the epoxy system, introduces reversible metal ion-carboxyl dynamic coordination into the crosslinked epoxy network through the transformation between chemical crosslinking and physical crosslinking, so as to construct a dynamic crosslinking network in the traditional epoxy resin, and the dynamic crosslinking network and long flexible chain segment endow the epoxy system with excellent stretchable performance. In addition, the introduction of long flexible chain segment increases the free volume of molecular chain in the epoxy system, reduces the Tg of the epoxy system, and converts the traditional brittle epoxy system into a flexible epoxy system, providing a simple and effective strategy for the construction of a flexible epoxy resin system.

[0005] The purpose of the present application is realized by the following technical scheme:

[0006] A preparation method of an epoxy elastomer with super flexibility, which adopts a two-step method to complete the synthesis of the epoxy elastomer, and the specific steps are as follows:

[0007] Step one, preparation of epoxy elastomer A:

[0008] The epoxy elastomer A is prepared according to the following reaction flow:

[0009]

[0010] The specific steps are as follows:

[0011] Step one, the epoxy resin A and the epoxy resin B are mixed at room temperature in a certain proportion for 1-3 hours to form a uniform mixture, named epoxy resin C, wherein:

[0012] The epoxy resin B has the following molecular structure characteristics:

[0013]

[0014] In the formula, R1, R2 are not limited to one or more of alkyl, amino, heterocyclic ring, aromatic heterocyclic ring, hydrogen, fluorine; n is an arbitrary number between 1-100;

[0015] The epoxy resin A has the following molecular structure characteristics:

[0016]

[0017] In the formula, R3, R4 are not limited to one or more of alkyl, amino, heterocyclic ring, aromatic heterocyclic ring, hydrogen, fluorine;

[0018] The mass ratio of the epoxy resin A and the epoxy resin B is 1:1-1:10;

[0019] Step two, the curing agent A and the curing agent B are mixed at 50-80°C in a certain proportion for 1-3 hours to form a uniform mixture, named curing agent C, wherein:

[0020] The curing agent A is a long-chain flexible curing agent, which has the following molecular structure characteristics:

[0021]

[0022] In the formula, R5 is not limited to one or more of hydrogen, alkyl, long-chain alkyl, hydroxymethyl, carboxymethyl; n is an arbitrary number between 1-100;

[0023] The curing agent B is a long-chain flexible curing agent, which has the following molecular structure characteristics:

[0024]

[0025] In the formula, R6, R7 are not limited to one or more of hydrogen, alkyl, long-chain alkyl, hydroxymethyl, carboxymethyl; n is an arbitrary number between 1-100;

[0026] The mass ratio of the curing agent A to the curing agent B is 1:1-1:10.

[0027] Step one three, the epoxy resin C and the curing agent C are stirred and mixed uniformly at room temperature to form a prepolymer solution;

[0028] The mass ratio of the epoxy resin to the curing agent is 1:4-1:9.

[0029] Step one four, the prepolymer solution is transferred to a mold and cured at a temperature of 50-150 DEG C for 4-48 hours to obtain a precursor, i.e., an epoxy elastomer A, which contains the following breakable crosslinking structure:

[0030] ;

[0031] Step two, preparation of an epoxy elastomer with super flexibility:

[0032] The epoxy elastomer with super flexibility is prepared according to the following reaction scheme:

[0033]

[0034] The specific steps are as follows:

[0035] Step two one, the epoxy elastomer A is soaked in an alkali solution for hydrolysis, wherein:

[0036] The alkali is not limited to one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide and potassium ethoxide;

[0037] The concentration of the alkali solution is 0.5-1.5 mol / L;

[0038] The hydrolysis temperature is 80-100 DEG C, and the time is 1-4 hours;

[0039] Step two two, after the hydrolysis is completed, it is taken out and soaked in a ferric ion solution, wherein:

[0040] The concentration of the ferric ion solution is 0.5-2 mol / L;

[0041] In the ferric ion solution, the ferric salt is not limited to one or more of ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric acetate tetrahydrate and ferric sulfate heptahydrate;

[0042] Step two three, after soaking for 20-30 hours, it is taken out and dried in a vacuum oven to obtain an epoxy elastomer with super flexibility, wherein:

[0043] The drying temperature is 80-120 DEG C, and the time is 5-12 hours.

[0044] Compared with the prior art, the present application has the following advantages:

[0045] 1、The present application constructs a flexible epoxy elastomer by introducing long flexible molecular structure into the traditional epoxy resin network. Further, by hydrolyzing the ester bond in the molecular network, the birth of carboxyl group is guided, and then the coordination between the introduced trivalent metal ion and the carboxyl group is utilized to convert part of the chemical crosslinking points into physical crosslinking points, so that the flexible epoxy molecular network has more excellent energy dissipation capacity, and the epoxy elastomer is endowed with super flexibility from the macroscopic aspect.

[0046] 2、The present application provides a new idea and construction scheme for converting the traditional rigid epoxy material into a flexible elastomer material, and provides another new material for selection in the field of flexible strain materials. DETAILED DESCRIPTION

[0047] The technical solutions of the present application are further described below in combination with examples, but are not limited thereto, and any modification or equivalent replacement to the technical solutions of the present application without departing from the spirit and scope of the present application shall be encompassed in the protection scope of the present application.

[0048] Example 1: Preparation of precursor A

[0049] Take 3g of curing agent A and 3g of curing agent B to stir and mix at 60℃ for 2 hours to form a uniform mixture, which is named as curing agent C; take 0.5g of epoxy resin A and 1.0g of epoxy resin B to stir and mix at room temperature for 2 hours to form a uniform mixture, which is named as epoxy resin C; then add the epoxy resin C into the curing agent C, stir at room temperature for 5 minutes, mix uniformly to form a prepolymer liquid A, and remove bubbles by ultrasonic. Then transfer to a circular mold, and cure at 120℃ for 7 hours to obtain the precursor A, and the mechanical properties are shown in Table 1.

[0050] In this example, the molecular structure of the curing agent A is as follows:

[0051] .

[0052] In this example, the molecular structure of the curing agent B is as follows:

[0053] .

[0054] In this example, the molecular structure of the epoxy resin A is as follows:

[0055] .

[0056] In this example, the molecular structure of the epoxy resin B is as follows:

[0057] .

[0058] The molecular structure of the precursor A in this embodiment is as follows:

[0059] .

[0060] Table 1: Mechanical properties of the precursor A

[0061]

[0062] Example 2: Preparation of the precursor B

[0063] Take 2 g of the curing agent A1 and 4 g of the curing agent B1, mix them at 60°C for 2 hours to form a uniform mixture, and name it as the curing agent C1. Take 0.2 g of the epoxy resin A1 and 1.3 g of the epoxy resin B1, mix them at room temperature for 2 hours to form a uniform mixture, and name it as the epoxy resin C1. Then, add the epoxy resin C1 into the curing agent C1, mix them at room temperature for 5 minutes to form a uniform mixture, and name it as the prepolymer liquid B. Perform ultrasonic defoaming. Then, transfer it into a circular mold, and cure it at 120°C for 7 hours to obtain the precursor B. The mechanical properties of the precursor B are shown in Table 2.

[0064] The molecular structure of the curing agent A1 in this embodiment is as follows:

[0065] .

[0066] The molecular structure of the curing agent B1 in this embodiment is as follows:

[0067] .

[0068] The molecular structure of the epoxy resin A1 in this embodiment is as follows:

[0069] .

[0070] The molecular structure of the epoxy resin B1 in this embodiment is as follows:

[0071] .

[0072] The molecular structure of the precursor B in this embodiment is as follows:

[0073] .

[0074] Table 2: Mechanical properties of the precursor B

[0075]

[0076] Example 3: Preparation of the precursor C

[0077] Take 2 g of curing agent A2, 4 g of curing agent B2, stir and mix at 60°C for 2 hours to form a uniform mixture, named curing agent C2; take 0.2 g of epoxy resin A1 and 1.3 g of epoxy resin B1 at room temperature, stir and mix for 2 hours to form a uniform mixture, named epoxy resin C2; then add epoxy resin C2 to curing agent C2, stir at room temperature for 5 minutes, mix uniformly to form a prepolymer liquid C, and use ultrasonic to remove bubbles. Then transfer to a circular mold, cure at 120°C for 7 hours to obtain a precursor C, and the mechanical properties are shown in Table 2.

[0078] In this embodiment, the molecular structure of curing agent A2 is:

[0079] .

[0080] In this embodiment, the molecular structure of curing agent B2 is:

[0081] .

[0082] In this embodiment, the molecular structure of epoxy resin A2 is:

[0083] .

[0084] In this embodiment, the molecular structure of epoxy resin B2 is:

[0085] .

[0086] In this embodiment, the molecular structure of precursor C is:

[0087] .

[0088] Example 4: Preparation of super flexible epoxy elastomer A from precursor A

[0089] The precursor A is immersed in 1 mol / L NaOH aqueous solution, and then hydrolyzed at 95°C for 2 hours. After hydrolysis, take out, immerse in 1.0 mol / L ferric chloride ion solution, immerse for 24 hours, take out, dry in 80°C vacuum oven for 12h, obtain super flexible epoxy elastomer A, and the mechanical properties are shown in Table 3.

[0090] Table 3 Mechanical properties of super flexible epoxy elastomer A

[0091]

[0092] Example 5: Preparation of super flexible epoxy elastomer B from precursor B

[0093] The precursor B was immersed in 1 mol / L aqueous potassium ethoxide solution, and then hydrolyzed at 85°C for 3 hours. After the hydrolysis was completed, it was taken out, immersed in 1.5 mol / L aqueous ferric nitrate tetrahydrate solution, and after immersion for 48 hours, it was taken out and dried in a vacuum oven at 80°C for 12 h to obtain a super-flexible epoxy elastomer B, and the mechanical properties thereof are shown in Table 4.

[0094] Table 4 Mechanical properties of the super-flexible epoxy elastomer B

[0095]

Claims

1. A method for preparing an ultra-flexible epoxy elastomer, characterized in that The method comprises the following steps: Step 1: Preparation of epoxy elastomer A: Step 11: Epoxy resin A and epoxy resin B are stirred and mixed in a certain proportion at room temperature for 1 to 3 hours to form a uniform mixture, which is named epoxy resin C, wherein: The epoxy resin A has the following molecular structure characteristics: Wherein, R3 and R4 are one or more of alkyl, amino, heterocycle, hydrogen, and fluorine; The epoxy resin B has the following molecular structure characteristics: In the formula, R1 and R2 are one or more of alkyl, amino, heterocycle, hydrogen, and fluorine; n is any number between 1 and 100; The mass ratio of the epoxy resin A to the epoxy resin B is 1:1 to 1:10; Step 1 and 2: Stir and mix curing agent A and curing agent B in a certain proportion at 50-80°C for 1-3 hours to form a uniform mixture, named curing agent C, wherein: The curing agent A has the following molecular structure characteristics: In the formula, R5 is one or more of hydrogen, alkyl, hydroxymethyl, and carboxymethyl; n is any number between 1 and 100; The curing agent B has the following molecular structure characteristics: In the formula, R6 and R7 are one or more of hydrogen, alkyl, hydroxymethyl, and carboxymethyl; n is any number between 1 and 100; The mass ratio of the curing agent A to the curing agent B is 1:1 to 1:10; Step 13: Stir and mix epoxy resin C and curing agent C at room temperature to form a prepolymer solution; The mass ratio of the epoxy resin C to the curing agent C is 1:4 to 1:9; Step 14: Transfer the prepolymer solution to a mold and cure it at a temperature of 50-150° C. for 4-48 hours to obtain a precursor, namely, epoxy elastomer A; Step 2: Preparation of ultra-flexible epoxy elastomer: Step 2: Immerse the epoxy elastomer A in an alkaline solution for hydrolysis. Step 22: After the hydrolysis is completed, take out the solution and soak it in a solution of trivalent iron ions; Step 2: Take out and dry in a vacuum oven to obtain an ultra-flexible epoxy elastomer.

2. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, wherein The epoxy elastomer A contains the following breakable cross-linked structure: 。 3. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, wherein The alkali is one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, and potassium ethoxide.

4. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, wherein The concentration of the alkaline solution is 0.5-1.5 mol / L.

5. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, wherein The hydrolysis temperature is 80-100° C., and the time is 1-4 hours.

6. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, characterized in that The concentration of the trivalent iron ion solution is 0.5-2 mol / L.

7. The method for preparing an ultra-flexible epoxy elastomer according to claim 1 or 6, characterized in that In the trivalent iron ion solution, the iron salt is one or more of ferric chloride hexahydrate, ferric nitrate nonahydrate, ferric acetate tetrahydrate, and ferric sulfate heptahydrate.

8. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, characterized in that The soaking time is 20 to 30 hours.

9. The method for preparing an ultra-flexible epoxy elastomer according to claim 1, wherein The drying temperature is 80-120° C. and the drying time is 5-12 hours.

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