Bio-based epoxy resin containing dual-network structure and preparation method of bio-based epoxy resin

Abstract

The preparation method comprises the following steps: by taking a vinyl-containing bio-based epoxy monomer as an epoxy monomer, adding an initiator and a curing agent, and carrying out cross-linking reaction, so that a cross-linked network I is a linear polyolefin structure obtained by initiating double-bond polymerization through free radicals; and the second cross-linked network is a cross-linked structure obtained by stepwise polymerization of the curing agent and epoxy, and the glass transition temperature of the epoxy resin is effectively increased due to high cross-linked density brought by the double-network structure. The epoxy monomer provided by the invention takes a biological-derived phenolic compound as a raw material, and the resin has extremely low viscosity before curing and extremely high glass-transition temperature (gt; the method can be used in the field of high-temperature and high-frequency third-generation semiconductor packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of thermosetting resins, and in particular relates to a high-performance bio-based epoxy resin containing a double network structure and a preparation method thereof. Background Art

[0002] Epoxy resin is a type of thermosetting resin formed by epoxy monomers and curing agents. Due to its three-dimensional cross-linked structure and excellent thermal, mechanical and dielectric properties, epoxy resin is widely used in the field of electronic packaging, accounting for more than 70% of the electronic packaging resin market share.

[0003] At present, commercial epoxy resins are mainly bisphenol A diglycidyl ether (DGEBA). However, due to factors such as the fatty chain segments in DGEBA and the diluents introduced during the processing, the current epoxy resins cannot meet the packaging materials of the third-generation semiconductors characterized by high temperature and high frequency. Double network polymers are materials composed of two mutually cross-linked three-dimensional networks, which are mainly used in gels. Their unique interpenetrating structure can effectively overcome the deficiencies in thermal and mechanical properties of polymers caused by single network defects. There are usually two methods for introducing double network strategies into epoxy resins. The first is to prepare a bifunctional epoxy monomer, and the double networks obtained after curing are all covalent networks. For example, the patent with application number 201410049163.9 discloses an epoxy monomer containing maleimide, but the preparation of epoxy monomers is very complicated and difficult to purify. The second is to introduce a second strong polar compound to form a non-covalent cross-linked structure with the epoxy resin, such as the patent with application number 201610545457.X discloses a double network cross-linked epoxy resin formed by adding ionic liquids. However, the introduction of highly polar ionic liquids will seriously affect the dielectric properties of the resin and cannot be used in the field of electronic packaging.

[0004] In addition, petrochemical epoxy resins have been proven to be extremely harmful to the environment and human body. Bio-based epoxy resins have attracted widespread attention due to their renewable raw materials and low environmental pollution during the preparation process. Summary of the invention

[0005] Aiming at the problems of low glass transition temperature and poor thermal stability of epoxy resin, the present invention provides a method for preparing a bio-based derived double network cross-linked epoxy resin.

[0006] The technical solution provided by the present invention is:

[0007] A bio-based epoxy resin containing a double network structure, comprising the following components: a bio-based epoxy monomer containing a vinyl group, a curing agent and an initiator;

[0008] The bio-based epoxy monomer containing vinyl groups is prepared by the following method:

[0009] (1) The lignin-derived phenolic compound represented by Formula I is subjected to a decarboxylation reaction under the action of a Lewis base to obtain a vinyl phenolic compound represented by Formula II;

[0010] (2) the vinyl phenol compound represented by formula II and epichlorohydrin undergo epoxidation reaction under the catalysis of sodium hydroxide to prepare a bio-based epoxy monomer containing a vinyl group;

[0011] The reaction formula is as follows:

[0012]

[0013] In Formula I or Formula II, R 1 , R 2 , R 3 , R 4 Each independently represents any of the following structures, R 1 , R 2 , R 3 , R 4 Contains at least one hydroxyl group:

[0014]

[0015] Preferably, in step (1), the reaction temperature of the decarboxylation reaction is 20 to 120° C., preferably 60 to 120° C.; and the reaction time is 0.5 to 6 h, preferably 2 to 6 h.

[0016] Preferably, in step (1), the decarboxylation reaction is carried out in an organic solvent A, and the organic solvent A is selected from one or more of tetrahydrofuran, benzene, toluene, hexane, diethyl ether, N,N-dimethylformamide, acetone, dimethyl sulfoxide, 1,4-dioxane, pyridine, and acetonitrile, preferably N,N-dimethylformamide or acetone.

[0017] Preferably, in step (1), the structure of the Lewis base is selected from one or more of the following.

[0018]

[0019] A, B, and C are each independently a substituted or unsubstituted C1-10 aliphatic carbon chain; preferably, A, B, and C are each independently a C1-C10 alkyl group.

[0020] More preferably, the Lewis base is triethylamine or diisopropylethylamine.

[0021] The molar ratio of the lignin-derived phenolic compound represented by formula I to the Lewis base is preferably 1:2-3.

[0022] The volume usage of the organic solvent A is 0.1-2 L / mol based on the amount of the lignin-derived phenolic compound represented by Formula I.

[0023] In the step (1), after the decarboxylation reaction is completed, the reaction solution is post-treated to obtain the vinyl phenol compound shown in formula II. The post-treatment method of the reaction solution is generally: the reaction solution is cooled to room temperature, the excess Lewis base and organic solvent are evaporated to remove, the crude product is washed, extracted with ether, and the organic phase is vacuum dried to obtain the vinyl phenol compound shown in formula II.

[0024] In the step (2), the molar ratio of the vinyl phenol compound represented by formula II, epichlorohydrin and sodium hydroxide is 1:8-15:2-5.

[0025] The reaction temperature of the epoxidation reaction is 0 to 100°C, preferably 60 to 100°C.

[0026] The reaction time is 0.1 to 2 hours, preferably 0.5 to 2 hours.

[0027] Preferably, in step (2), the epoxidation reaction is carried out in an organic solvent B. The organic solvent B is selected from one or more of tetrahydrofuran, benzene, toluene, ethyl acetate, 1,4-dioxane, pyridine, acetonitrile, ethanol, and isopropanol, preferably ethanol, isopropanol or ethyl acetate.

[0028] The volume amount of the organic solvent B is 0.5 to 2 L / mol based on the amount of the vinyl phenol compound represented by formula II.

[0029] Preferably, in step (2), sodium hydroxide is added dropwise in the form of a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.1 to 5 mol / L;

[0030] In the step (2), after the epoxidation reaction is completed, the reaction solution is cooled to room temperature and then washed with deionized water, and then vacuum dried to obtain a bio-based epoxy monomer.

[0031] In the present invention, for the first time, a bio-based epoxy monomer containing vinyl groups is used to prepare an epoxy resin having a double network structure. The raw materials of the epoxy monomers are derived from a type of phenolic compound containing an acrylic acid structure that exists in large quantities in lignin. The preparation method is simple. The bio-based epoxy monomer containing vinyl groups has an extremely low viscosity, and no diluent needs to be added during the processing. The cured resin can exhibit an extremely high glass transition temperature (>200°C) and excellent thermal stability due to the high crosslinking density formed by the double network.

[0032] Furthermore, the curing agent is at least one of isophoronediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, triethylenetetramine, and (propane-2,2-diylbis(furan-5,2-diyl))dimethylamine, preferably isophoronediamine or diaminodiphenylmethane.

[0033] Preferably, the initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, hydrogen peroxide, potassium persulfate, ammonium persulfate, tert-butyl perbenzoate, and dibenzoyl peroxide, preferably azobisisobutyronitrile or dibenzoyl peroxide.

[0034] Furthermore, the molar ratio of the vinyl-containing bio-based epoxy monomer to the curing agent is 1:0.2-0.8.

[0035] The mass amount of the initiator is 0.5-2% of the mass amount of the vinyl-containing bio-based epoxy monomer, preferably 1%.

[0036] The present invention also provides the use of a vinyl-containing bio-based epoxy monomer in preparing a bio-based epoxy resin with a double network structure.

[0037] The bio-based epoxy monomer containing vinyl groups is prepared by the following method:

[0038] (1) The lignin-derived phenolic compound represented by Formula I is subjected to a decarboxylation reaction under the action of a Lewis base to obtain a vinyl phenolic compound represented by Formula II;

[0039] (2) The vinyl phenol compound represented by formula II and epichlorohydrin undergo epoxidation reaction under the catalysis of sodium hydroxide to prepare a bio-based epoxy monomer containing a vinyl group.

[0040] The present invention also provides a bio-based epoxy resin adhesive containing a double network structure, which is prepared by mixing a bio-based epoxy monomer containing a vinyl group, a curing agent and an initiator in a certain proportion.

[0041] The bio-based epoxy resin glue containing a double network structure can be directly cured in a mold to obtain a cross-linked cured epoxy resin of a desired shape, or can be impregnated with reinforcing fibers and hot-pressed to obtain a fiber-reinforced composite material.

[0042] The present invention also provides a cured product of a bio-based epoxy resin containing a double network structure, which is obtained by mixing and curing the bio-based epoxy resin containing a double network structure. Specifically, the cured product can be prepared by the following method: a vinyl-containing bio-based epoxy monomer, a curing agent and an initiator are mixed in proportion to obtain a glue solution, which is then put into a mold and heated in stages to obtain a cured product of the bio-based epoxy resin containing a double network structure.

[0043] The cured product of the bio-based epoxy resin containing a double network structure provided by the present invention has a glass transition temperature of more than 200°C.

[0044] Preferably, the staged heating is carried out at 80-110° C. for 1-3 hours and at 120-160° C. for 1-3 hours.

[0045] The present invention also provides an epoxy resin fiber reinforced composite material, comprising the bio-based epoxy resin containing a double network structure and reinforcing fibers.

[0046] The reinforcing fibers may be reinforcing fiber cloth, such as carbon fiber cloth, glass fiber cloth, and the like.

[0047] Furthermore, the epoxy resin fiber reinforced composite material can be prepared by the following method: a vinyl-containing bio-based epoxy monomer, a curing agent and an initiator are mixed in proportion to obtain a glue solution, a reinforcing fiber cloth is immersed in the above-mentioned glue solution, and taken out after immersion for 20 to 30 seconds, 3 to 10 pieces of reinforcing fiber cloth immersed in the glue solution are stacked to obtain a prepreg, and the prepreg is hot-pressed to obtain the epoxy resin fiber reinforced composite material.

[0048] The hot pressing process is: heating at 80-85° C. for 1-3 hours, or heating at 120-130° C. for 1-3 hours under a pressure of 10-12 MPa.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) The raw materials of epoxy monomers are derived from a class of phenolic compounds containing acrylic acid structures that are abundant in lignin. The raw materials are cheap and readily available, and the preparation method is simple. Bio-based epoxy monomers containing vinyl groups have a single benzene ring structure, have very low viscosity before curing, are highly processable, and do not require the addition of diluents during the processing process.

[0051] (2) The epoxy monomer containing double bonds has two reactive functional groups. The temperature rise curing can simultaneously cause the step-by-step polymerization of epoxy and amine and the free radical polymerization of double bonds, thereby forming a double network cross-linked structure. Network one is a linear polyolefin structure obtained by free radical-initiated double bond polymerization, and network two is a cross-linked structure obtained by the step-by-step polymerization of the curing agent and epoxy. The high cross-linking density brought by the double network structure effectively improves the glass transition temperature (>200°C) and thermal stability of the resin, and can be used in the field of high-temperature and high-frequency third-generation semiconductor packaging. The epoxy resin fiber-reinforced composite material prepared by the epoxy resin of the present invention has an extremely high storage modulus (1.2GPa) and glass transition temperature (>200°C), which meets the preparation requirements of high-performance copper clad laminates. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is the H NMR spectrum of the caffeic acid decarboxylation product DCA obtained in Example 1.

[0053] Figure 2This is the H-NMR spectrum of the epoxy monomer DGEDCA obtained in Example 1.

[0054] Figure 3 This is the viscosity curve of the epoxy monomer DGEDCA obtained in Example 1.

[0055] Figure 4 This is the dynamic thermomechanical analysis curve of the epoxy resin P-DGEDCA obtained in Example 1.

[0056] Figure 5 This is the H NMR spectrum of the ferulic acid decarboxylation product DFA obtained in Example 2.

[0057] Figure 6 This is a viscosity curve of the epoxy monomer GEDFA obtained in Example 2.

[0058] Figure 7 Dynamic thermomechanical analysis curves of the epoxy resins P-GEDFA and P-TGEDTHA obtained in Examples 2 and 3.

[0059] Figure 8 This is a morphology picture of the epoxy resin glass fiber reinforced composite material obtained in Example 4. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0061] The general synthesis reaction formula of the halogen-free epoxy resin provided by the present invention is shown below.

[0062]

[0063] Example 1

[0064]

[0065] Caffeic acid (CA, 36.0 g, 0.2 mol) and triethylamine (40.0 g, 0.4 mol) were dissolved in N, N-dimethylformamide (100 mL) and heated at 100 ° C with stirring for 3 h. After the reaction solution was cooled to room temperature, triethylamine and N, N-dimethylformamide were removed by rotary evaporation. The crude product was washed three times with deionized water, and the organic phase was extracted with ether. The organic phase was vacuum dried to obtain the decarboxylation product, a pale yellow liquid DCA.

[0066] Dissolve DCA (13.6 g, 0.1 mol) and epichlorohydrin (92.5 g, 1.0 mol) in ethyl acetate (100 mL), stir at 80°C for 10 min, then slowly dropwise add NaOH solution (1 M, 0.24 mol), continue heating and stirring for 1 h after the addition is complete. After the reaction solution is cooled to room temperature, wash with deionized water, and vacuum dry to obtain the epoxy monomer DGEDCA.

[0067] DGEDCA (2.48 g, 0.01 mol), isophorone diamine (0.85 g, 0.005 mol), and dibenzoyl peroxide (0.025 g) were mixed evenly and then placed in a forced air drying oven for segmented curing to obtain a bio-based epoxy resin P-DGEDCA. The specific steps of segmented curing were: heating at 80°C for 2 h and heating at 120°C for 2 h.

[0068] like Figure 1 The figure shows the H NMR spectrum of the caffeic acid decarboxylation product DCA prepared in this example. The three signal peaks with chemical shifts of 5.1 ppm, 5.6 ppm and 6.5 ppm represent the hydrogen atom signals of the double bonds after decarboxylation, indicating that DCA has been successfully synthesized.

[0069] like Figure 2 The figure shows the H NMR spectrum of the epoxy monomer DGEDCA prepared in this example. The three signal peaks with chemical shifts of 2.8 ppm, 2.9 ppm and 3.3 ppm represent the hydrogen atom signals of the epoxy ring, indicating that DGEDCA has been successfully synthesized.

[0070] like Figure 3 The figure shows the viscosity curve of the epoxy monomer DGEDCA prepared in this example. Compared with the bisphenol A epoxy resin DGEBA, DGEDCA has a lower viscosity, and the viscosity at 50° C. is less than 1 Pas, and has good processability.

[0071] like Figure 4 The dynamic thermomechanical analysis curve of the double network epoxy resin P-DGEDCA prepared in this example is shown. The resin has a very high storage modulus (3200 MPa, 30°C) and glass transition temperature (216°C), which is much higher than that of bisphenol A epoxy resin cured with isophorone diamine (156°C).

[0072] Example 2

[0073]

[0074] Dissolve ferulic acid (FA, 38.8 g, 0.2 mol) and triethylamine (40.0 g, 0.4 mol) in N, N-dimethylformamide (100 mL) and heat at 120°C with stirring for 2 h. After the reaction solution is cooled to room temperature, remove triethylamine and N, N-dimethylformamide by rotary evaporation. The crude product is washed three times with deionized water, and the organic phase is extracted with dichloromethane. The organic phase is vacuum dried to obtain the decarboxylation product, a light yellow liquid DFA.

[0075] DFA (15.0 g, 0.1 mol) and epichlorohydrin (92.5 g, 1.0 mol) were dissolved in isopropanol (100 mL), stirred at 100°C for 10 min, and then slowly added with NaOH solution (0.5 M, 0.24 mol). After the addition was complete, the mixture was heated and stirred for 0.5 h. The reaction solution was cooled to room temperature, washed with deionized water, and vacuum dried to obtain the epoxy monomer GEDFA.

[0076] GEDFA (1.92 g, 0.01 mol), diaminodiphenylmethane (0.95 g, 0.0025 mol), and azobisisobutyronitrile (0.019 g) were mixed evenly and placed in a forced air drying oven for segmented curing to obtain a bio-based epoxy resin P-GEDFA. The specific steps of segmented curing were: heating at 100°C for 2 h and heating at 160°C for 2 h.

[0077] like Figure 5 The figure shows the H NMR spectrum of the epoxy monomer GEDFA prepared in this example. The three signal peaks with chemical shifts of 2.8 ppm, 2.9 ppm and 3.3 ppm represent the hydrogen atom signals of the epoxy ring, indicating that GEDFA has been successfully synthesized.

[0078] like Figure 6 The graph shows the viscosity curve of the epoxy monomer GEDFA prepared in this example. Compared with the bisphenol A epoxy resin DGEBA, GEDFA has a lower viscosity, and the viscosity at 40° C. is less than 1 Pas, and has good processability.

[0079] like Figure 7 The figure shows the dynamic thermomechanical analysis curve of the double network epoxy resin P-GEDFA prepared in this example. The glass transition temperature of the resin is 202°C.

[0080] Example 3

[0081]

[0082] 3,4,5-trihydroxycinnamic acid (THA, 39.2g, 0.2mol) and triethylamine (40.0g, 0.4mol) were dissolved in acetone (100mL) and heated at 60℃ with stirring for 6h. After the reaction solution was cooled to room temperature, triethylamine and N,N-dimethylformamide were removed by rotary evaporation. The crude product was washed three times with deionized water, and the organic phase was extracted with dichloromethane. The organic phase was vacuum dried to obtain the decarboxylation product, a light yellow liquid DTHA.

[0083] Dissolve DTHA (15.2 g, 0.1 mol) and epichlorohydrin (92.5 g, 1.0 mol) in ethanol (100 mL), stir at 60 ° C for 10 min, then slowly add NaOH solution (0.5 M, 0.24 mol), continue heating and stirring for 2 h after the addition is complete. After the reaction solution is cooled to room temperature, wash with deionized water, and vacuum dry to obtain the epoxy monomer TGEDTHA.

[0084] TGEDTHA (3.20 g, 0.01 mol), (propane-2,2-diylbis(furan-5,2-diyl))dimethylamine (1.755 g, 0.0075 mol), and azobisisobutyronitrile (0.032 g) were mixed evenly and placed in a forced air drying oven for segmented curing to obtain bio-based epoxy resin P-TGEDTHA. The specific steps of segmented curing were: heating at 80°C for 2 h and heating at 120°C for 2 h.

[0085] like Figure 7 The dynamic thermomechanical analysis curve of the double network epoxy resin P-TGEDTHA prepared in this example is shown. The glass transition temperature of the resin is 231°C.

[0086] Example 4

[0087] Preparation of DGEDCA-derived glass fiber composites:

[0088] DGEDCA (24.8g, 0.1mol), isophorone diamine (8.5g, 0.05mol), dibenzoyl peroxide (0.25g) were mixed and stirred at room temperature for 10min to obtain a glue solution. A glass fiber cloth (10cm×10cm) was immersed in the above glue solution and taken out after immersion for 20s. Five pieces of treated glass fiber cloth were stacked to obtain a prepreg, and hot-pressed to obtain an epoxy resin glass fiber composite material. Hot-pressing conditions: 80℃ and 120℃ were heated for 2h each under a pressure of 10MPa.

[0089] The epoxy resin glass fiber composite material obtained looks like Figure 8 As shown, DMA test was performed on the cured resin, and the material had extremely high storage modulus (1.2 GPa) and glass transition temperature (220°C), meeting the preparation requirements of high-performance copper clad laminates.

Claims

1. A bio-based epoxy resin containing a double network structure, comprising the following components: a bio-based epoxy monomer containing a vinyl group, a curing agent and an initiator; Features The bio-based epoxy monomer containing vinyl groups is prepared by the following method: (1) The lignin-derived phenolic compound represented by Formula I is subjected to a decarboxylation reaction under the action of a Lewis base to obtain a vinyl phenolic compound represented by Formula II; (2) the vinyl phenol compound represented by formula II and epichlorohydrin undergo epoxidation reaction under the catalysis of sodium hydroxide to prepare a bio-based epoxy monomer containing a vinyl group; The reaction formula is as follows: In Formula I or Formula II, R1, R2, R3, and R4 are each independently represented by any one of the following structures, and at least one of R1, R2, R3, and R4 contains a hydroxyl group:

2. The bio-based epoxy resin containing a double network structure according to claim 1, characterized in that In the step (1), the structure of the Lewis base is selected from one or more of the following A, B, and C each independently represent a substituted or unsubstituted C1-C10 aliphatic carbon chain.

3. The bio-based epoxy resin containing a double network structure as claimed in claim 1, characterized in that In the step (1), the molar ratio of the lignin-derived phenolic compound represented by formula I to the Lewis base is 1:2-3; the reaction temperature of the decarboxylation reaction is 20-120° C.; and the reaction time is 0.5-6 h.

4. The bio-based epoxy resin containing a double network structure according to claim 1, characterized in that In the step (2), the molar ratio of the vinyl phenol compound represented by formula II, epichlorohydrin and sodium hydroxide is 1:8-15:2-5.

5. The bio-based epoxy resin containing a double network structure as claimed in claim 1, characterized in that The curing agent is at least one of isophoronediamine, diaminodiphenylmethane, diaminodiphenyl sulfone, triethylenetetramine, and (propane-2,2-diylbis(furan-5,2-diyl))dimethylamine; The initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, hydrogen peroxide, potassium persulfate, ammonium persulfate, tert-butyl perbenzoate, and dibenzoyl peroxide.

6. The bio-based epoxy resin containing a double network structure according to claim 1, characterized in that The molar ratio of the vinyl-containing bio-based epoxy monomer to the curing agent is 1:0.2-0.8; The mass amount of the initiator is 0.5-2% of the mass amount of the vinyl-containing bio-based epoxy monomer.

7. Use of a vinyl-containing bio-based epoxy monomer in the preparation of a bio-based epoxy resin with a double network structure, characterized in that The bio-based epoxy monomer containing vinyl groups is prepared by the following method: (1) The lignin-derived phenolic compound represented by Formula I is subjected to a decarboxylation reaction under the action of a Lewis base to obtain a vinyl phenolic compound represented by Formula II; (2) The vinyl phenol compound represented by formula II and epichlorohydrin undergo epoxidation reaction under the catalysis of sodium hydroxide to prepare a bio-based epoxy monomer containing a vinyl group.

8. A bio-based epoxy resin adhesive containing a double network structure, which is prepared from the bio-based epoxy resin containing a double network structure as described in any one of claims 1 to 6 by the following method: mixing a vinyl-containing bio-based epoxy monomer, a curing agent and an initiator to obtain a bio-based epoxy resin adhesive containing a double network structure.

9. A cured product of a bio-based epoxy resin containing a double network structure, obtained by mixing and curing the bio-based epoxy resin containing a double network structure according to any one of claims 1 to 6, characterized in that The glass transition temperature of the cured product is greater than 200°C.

10. An epoxy resin fiber reinforced composite material, comprising the bio-based epoxy resin containing a double network structure as claimed in any one of claims 1 to 6 and reinforcing fibers.

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