CN115160540A - High-modulus high-activity epoxy resin and synthesis method and application thereof - Google Patents

Abstract

The invention provides a polar epoxy resin monomer containing a typical structure shown in formula I, a synthetic preparation method and a curing system thereof. The polar epoxy resin monomer has high reactivity and can realize rapid curing, and an epoxy resin cured material obtained by the reaction of the polar epoxy resin monomer and a curing agent has high modulus and excellent thermo-mechanical property, and has important application value in the fields of conventional application of epoxy resin, rapid manufacturing of high-performance fiber reinforced composite materials, 3D printing of resin and the like.

Description

High-modulus high-activity epoxy resin and synthesis method and application thereof

Technical Field

The invention belongs to the field of advanced materials, and particularly relates to a high-modulus high-activity epoxy resin, a synthetic method and application thereof.

Background

Due to the characteristics of good processability, excellent adhesive property, mechanical property, electrical insulation property, chemical stability and the like, the epoxy resin is widely applied to pouring and packaging of electronic materials and in coatings, adhesives and composite material matrixes.

When the epoxy resin is used as a matrix of a composite material, the epoxy resin needs a long-time high-temperature curing condition, so that the large-scale production and preparation of the composite material taking the epoxy resin as the matrix are restricted. Currently, high performance fiber reinforced thermoset polymer Composites (CFRP) rely on forming in large, expensive autoclave or oven. For example, the CFRP fuselage of boeing 787 is estimated to require 350 Gigajoules (GJ) of energy in an 8 hour cure cycle and produces over 80 tons of carbon dioxide. Therefore, the fast curing epoxy resin has an important application prospect in the commercial field for the purpose of reducing production energy consumption and manufacturing cost, and has attracted great research interest. In addition, the fast curing epoxy resin has potential application value in the fields of 3D printing and the like, and is beneficial to further widening the application direction of the epoxy resin.

Self-curing forward polymerization is an important molding strategy for resin curing, and the resin is promoted to be cured spontaneously by using the exothermic heat of the polymerization process to provide continuous chemical power without more external energy, so that the manufacturing cost is greatly reduced. However, to date, most self-initiated polymers have failed to meet high performance requirements due to poor performance. For example, while acrylate monomers have the necessary energy density and reactivity to undergo rapid forward polymerization, the resulting polymers have much lower mechanical properties than the matrix polymers used in structural fiber reinforced polymer composites. In contrast, epoxy monomers can produce polymers with strong mechanical properties, but rapid polymerization remains challenging due to their low reactivity (Journal of Polymer Science Part A: polymer Chemistry,2010,48 (9): 2000-2005).

CFRP puts higher demands on mechanical properties in addition to the ability of epoxy resins to cure rapidly and spontaneously. The modulus of the fast curing materials is generally low, and the current CFRP facing unbalanced compression and tension conditions limits the wider application of the CFRP. Therefore, in order to better cope with various complicated application environments, epoxy resins with higher modulus are also becoming one of the hot fields of research.

In summary, in order to improve the compression performance of the composite material and promote the improvement of the manufacturability of the composite material, the fast-curing high-modulus epoxy resin is one of the necessary development directions in the field.

Disclosure of Invention

The invention aims to provide an epoxy resin with high modulus and high activity.

The invention provides an epoxy resin curing system, which comprises an epoxy resin monomer containing a structure shown in a formula I and a curing agent:

wherein R is ₁ 、R ₂ 、R ₃ Are each independently selected from hydrogen or

And R is ₁ 、R ₂ 、R ₃ At least one of which is

Further, the structure shown in formula I is:

further, the curing agent is an amine curing agent, an acid anhydride curing agent or an accelerator curing agent, wherein the amine curing agent is m-phenylenediamine, halogen substituted or unsubstituted diaminodiphenylmethane, 3,4' -diaminodiphenyl sulfone, diethyltoluenediamine or diaminopyridine; the acid anhydride curing agent is methyl nadic anhydride or phthalic anhydride; the accelerator curing agent is 1-methylimidazole or 2-ethyl-4-methylimidazole.

Further, the curing agent is an amine curing agent, preferably a halogen substituted or unsubstituted diaminodiphenylmethane, more preferably 3,3 '-dichloro-4, 4' -diaminodiphenylmethane or diethyltoluenediamine.

Further, the molar ratio of the active hydrogen of the amine-based curing agent to the epoxy group of the epoxy resin monomer is (0.8 to 2): 1, preferably 1.

Further, the curing system also comprises a diluent; the diluent is styrene oxide, phenyl glycidyl ether, resorcinol glycidyl ether or hydroquinone glycidyl ether, preferably styrene oxide;

preferably, the diluent is used in an amount of 5% to 10% w/w of the epoxy resin curing system.

The invention also provides an epoxy resin cured product, which is prepared by reacting the epoxy resin cured system at 130-140 ℃ for 2-5 hours and then reacting at 170-190 ℃ for 2-5 hours.

The invention also provides application of the epoxy resin cured product as a composite material matrix or a 3D printing material.

The invention also provides an epoxy resin monomer, which contains the following structure:

the invention also provides a preparation method of the epoxy resin monomer, which comprises the following steps:

(1) Under the action of catalyst, the epoxy halopropane and salicylaminol react at 90-110 deg.c for 4-12 hr;

(2) Cooling to below 70 ℃, adding alkali for reaction for 4-12 hours, cooling, filtering, standing for layering, and removing the catalyst and epihalohydrin in the supernatant to obtain the catalyst;

preferably, the epihalohydrin of step (1) is epichlorohydrin; the catalyst is benzyltriethylammonium bromide or 1-methylimidazole; and/or the base of step (2) is sodium hydroxide, preferably solid sodium hydroxide.

The invention has the beneficial effects that: the polar epoxy resin with a typical structure has high reactivity, the epoxy resin condensate obtained by the reaction with the curing agent has high modulus, particularly, the condensate prepared by a TEBAM curing system has good thermal mechanical property, and the polar epoxy resin has important application value in the fields of rapid manufacturing of high-performance fiber reinforced thermosetting polymer composite materials, resin 3D printing and the like.

Obviously, many modifications, substitutions, and variations are possible in light of the above teachings of the invention, without departing from the basic technical spirit of the invention, as defined by the following claims.

The present invention will be described in further detail with reference to the following examples. This should not be understood as limiting the scope of the above-described subject matter of the present invention to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention.

Drawings

FIG. 1 shows DSC spectra of DEBIM/MPD (comparative example 2) and TEBAM/DETDA (example 2) curing processes.

FIG. 2 is a plot of DMA performance for a DEBAM cured article (example 1) and a TEBAM cured article (example 2) versus E51 (comparative example 1).

FIG. 3 is a plot of heat residual weight for DEBAM cured (example 1) and TEBAM cured (example 2) versus E51 (comparative example 1).

Detailed Description

The raw materials and equipment used in the invention are known products, and are obtained by purchasing products sold in the market. The epoxy equivalent of the epoxy resin is determined according to the measurement results of GB/T4612-2008.

Example 1 preparation of resin monomer DEBAM of the invention and cured product thereof

1. Preparation of DEBAM

Adding epoxy chloropropane and salicylaminol into the flask, wherein the mass ratio of the epoxy chloropropane to the hydroxyl is 15. Benzyl triethyl ammonium bromide is selected as a reaction catalyst, and the addition amount of the benzyl triethyl ammonium bromide is 2.5-3% of the mass of the 3-hydroxybenzaldehyde- (4-hydroxy-phenylimine). The reaction is carried out at 100 ℃ for 4 to 12 hours. The flask was cooled to below 70 ℃, sodium hydroxide particles were added in portions, and the mixed solution was continuously stirred for 4-12 hours, cooled, and filtered. After standing and layering, the catalyst in the solution was extracted with deionized water, and epichlorohydrin was removed by concentration to obtain DEBAM.

¹ H NMR(400MHz，DMSO，DEBAM)δ10.01(s，0H)，7.76-7.61(m，2H)，7.49(dd，J＝8.4，7.3，1.8Hz，1H)，7.19(dd，J＝8.4，1.0Hz，1H)，7.18-6.87(m，3H)，6。87-6.63(m，1H)，4.56-4.45(m，1H)，4.31(dd，J＝11.4，2.7Hz，1H)，4.26-3.99(m，1H)，3.95-3.59(m，2H)，3.59-3.28(m，1H)，2.91-2.60(m，4H)。

FTIR(DEBAM)(KBr):ν(O＝CN-H)＝3396cm ^-1 ,νAr(C _β -H)＝3003,2921,2848cm ^-1 ,ω(C＝O)＝1706cm ^-1 _, νepoxy(C-O-C)＝909cm ^-1 。

Determination of the epoxy equivalent E according to GB/T4612-2008 _q =166.9, epoxy value E _v =0.515 (close to the theoretical epoxy value of 0.585), and the weight average molecular weight was measured to be 333.8.

Evidence of DEBAM structure:

and (4) successfully synthesizing.

2. Preparation of the cured product

Taking the DEBAM prepared in the step 1, 3 '-dichloro-4, 4' -diaminodiphenylmethane (MOCA) curing agent, and mixing the DEBAM and the 3,3 '-dichloro-4, 4' -diaminodiphenylmethane (MOCA) curing agent according to the molar ratio of the hydrogen atom carried by the amino group to the epoxy group of 1:1, and adding styrene oxide diluent accounting for 5% of the total mixed amount of the resin and the curing agent to dilute, reacting at 110 ℃ for 3 hours, 150 ℃ for 3 hours, and 200 ℃ for 3 hours, and curing to prepare a product (DEBAM +5% SO/MOCA).

Example 2 preparation of resin monomer TEBAM of the invention and cured product thereof

1. Preparation of TEBAM

Referring to the preparation method of example 1, salicylaminophenol was replaced with 3, 5-dihydroxy-N- (4-hydroxyphenyl) benzamide, and the catalyst was replaced with 1-methylimidazole in an amount of 1% of 3, 5-dihydroxy-N- (4-hydroxyphenyl) benzamide; thus obtaining TEBAM.

¹ H NMR(400MHz，DMSO，TEBAM)δ10.06(s，1H)，δ7.71-7.62(m，1H)，7.16(dd，J＝12.8，2.4Hz，1H)，7.01-6.93(m，1H)，6.93-6.71(m，1H)，6.43(s，1H)，4.42(ddd，J＝11.4，2.7，1.0Hz，1H)，4.36-4。14(m，1H)，4.03-3.90(m，1H)，3.90(dd，J＝5.6，3.7Hz，1H)，3.90-3.74(m，1H)，3.77-3.55(m，1H)，3。58-3.50(m，1H)，3.49-3.20(m，2H)，2.90-2.78(m，3H)，2.82-2.68(m，2H)，2.72-2.61(m，1H)。

FTIR(TEBAM)(KBr):ν(O-H)＝3397cm ^-1 ,νAr(C _β -H)＝3064,3001,2927cm ^-1 ,ω(C＝O)＝1718cm ^-1 _, β(O＝CN-H)＝1594cm ^-1 _, νepoxy(C-O-C)＝909cm ^-1 .

Determination of the epoxy equivalent E according to GB/T4612-2008 _q =194.0, epoxy value E _v =0.515 (close to the theoretical epoxy value of 0.726), and the weight average molecular weight was measured to be 388.0.

Demonstration of TEBAM structure:

and (4) successfully synthesizing.

2. Preparation of the cured product

Taking the TEBAM prepared in the step 1 and a diethyl toluene diamine (DETDA) curing agent, wherein the mixing ratio of the TEBAM curing agent to the diethyl toluene diamine (DETDA) curing agent is that the molar ratio of hydrogen atoms carried by amino groups to epoxy groups is 1:1, and adding styrene oxide diluent accounting for 10% of the total amount of the resin and curing agent mixed to dilute, reacting at 110 ℃ for 3 hours, at 150 ℃ for 3 hours, and at 200 ℃ for 3 hours, and curing to prepare a product (TEBAM +10% SO/DETDA).

Example 3 preparation of a resin monomer DEBAM cured product of the invention

Referring to the method of example 1, a cured product was prepared by adjusting the amount ratio of DEBAM and MOCA to 0.8.

Example 4 preparation of a resin monomer DEBAM cured product of the invention

Referring to the method of example 1, a cured product was prepared by adjusting the amount ratio of DEBAM and MOCA to 2 in terms of the molar ratio of hydrogen atoms carried by amino groups to epoxy groups.

Example 5 preparation of a cured product of a resin monomer TEBAM of the invention

Referring to the method of example 2, a cured product was prepared by adjusting the ratio of the amounts of TEBAM and DETDA to 0.8.

Example 6 preparation of a cured product of a resin monomer TEBAM of the invention

Referring to the procedure of example 2, a cured product was prepared by adjusting the ratio of the amounts of TEBAM and DETDA to 2.

Comparative examples 1,

Referring to the preparation method of example 1, the epoxy resin monomer was replaced with a commercially available epoxy resin E51, and the curing agent was replaced with diaminodiphenylmethane, in a mixing ratio of 1:1 (mass ratio of curing agent to resin 2.5.

Comparative examples 2,

1. Preparation of DEBIM

Epichlorohydrin and 3-hydroxybenzaldehyde- (4-hydroxyphenylimine) were added to the flask in a mass ratio of epichlorohydrin to hydroxyl of 15. Benzyl triethyl ammonium bromide is selected as a reaction catalyst, and the addition amount of the benzyl triethyl ammonium bromide is 2.5-3% of the mass of the 3-hydroxybenzaldehyde- (4-hydroxy-phenylimine). The reaction is carried out at 100 ℃ for 4 to 12 hours. The flask was cooled to below 70 ℃, the sodium hydroxide particles were added in portions, and the mixed solution was continuously stirred for 4-12 hours, cooled, and filtered. After standing and layering, extracting the catalyst in the solution with deionized water, and removing epichlorohydrin by concentration to obtain DEBIM.

Epoxy determination according to GB/T4612-2008Equivalent E _q =168.8, epoxy value E _v =0.592 (close to the theoretical epoxy value of 0.615) and the weight average molecular weight was measured to be 337.6.

¹ H NMR(500MHz，CHCl ₃ -d，DEBIM)δ8.42(s，1H)，7.03(t，3H)，6.68-6.93(t，3H)，6.33-6.62(D，2H)，4.89(s，1H)，4.45(s，1H)，3.11-3.34(DD，4H)，3.44-3.32(M，3H)，2.86-2.75(DD，2H)，2.49(D，2H)。

Method for binding reaction raw material 3-hydroxybenzaldehyde- (4-hydroxyphenylimine) ¹ HNMR (400MHz, DMSO) results: δ 9.62 (S, 1H), 9.48 (S, 1H), 8.50 (S, 1H), 7.32 (d, J =3.2hz, 1h), 7.31-7.26 (M, 2H), 7.21-7.14 (M, 2H), 6.91-6.85 (M, 1H), 6.82-6.76 (M, 2H), 2.54 (S, 1H).

The DEBIM structure can be confirmed:

and (4) successfully synthesizing.

2. Preparation of cured product

And (2) adding a m-phenylenediamine curing agent into the DEBIM prepared in the step (1) and uniformly mixing, wherein the proportion of the DEBIM to the m-phenylenediamine curing agent satisfies that the molar ratio of hydrogen atoms (namely active hydrogen) carried by amino groups to epoxy groups is 1:1 (i.e., the mass ratio of m-phenylenediamine to DEBIM is 1.6. Cured at 135 ℃ for 3 hours and 180 ℃ for 3 hours to obtain a cured product (DEBIM/MPD).

The beneficial effects of the present invention are demonstrated by the following experimental examples.

Experimental example 1 Activity of resin monomer

In the process of selecting the curing agent, the TEBAM and DEBAM epoxy resin monomer of the invention is found to be easy to implode at room temperature by using a common amine curing agent (m-phenylenediamine or diaminodiphenylmethane) or an imidazole curing agent. Only with the use of less active curing agents such as DETDA and MOCA, and the use of diluents, can the expected cured products be successfully synthesized, reflecting the high activity of the TEBAM and DEBAM epoxy resin monomers of the invention.

The preparation of the cured products of example 2 and comparative example 2 was further monitored by Differential Scanning Calorimetry (DSC) and the results are shown in figure 1. The peak curing temperature of the resin monomer DEBIM and the high-activity curing agent MPD in comparative example 2 is 149.4 ℃, and the curing temperature of the resin monomer TEBAM and the low-activity curing agent DETDA in example 2 is 148.8 ℃. The peak exotherm temperature for the less reactive curing agent is lower than for the more reactive curing agent.

The initial exothermic temperature (total exothermic amount is 5%) of the DEBIM and the high-activity curing agent MPD is 88.8 ℃, the initial exothermic temperature of the TEBAM and the low-activity curing agent DETDA is 53.5 ℃, and the exothermic peak of the reaction is very wide, so that the TEBAM and DEBAM resins of the embodiment 1 and the embodiment 2 have extremely high reactivity.

Experimental example 2 mechanical and thermomechanical properties of the cured product of synthetic resin

1. Experimental methods

The cured products of examples 1, 2 and comparative example 1 were subjected to flexural and tensile properties according to the test standards and sample specifications of table 1, and subjected to dynamic thermo-mechanical analysis (DMA).

Table 1 test standards and sample specifications

2. Results of the experiment

As shown in table 2.

TABLE 2 comparison of the composition and Properties of the different curing systems

It can be seen that the average flexural modulus and tensile modulus of the cured resin products of examples 1 and 2 are significantly improved as compared with those of a cured product of a conventional epoxy resin E51 (comparative example 1).

In particular, as shown in FIG. 2, it can be seen that the glass transition temperature of the cured TEBAM and DETDA are higher than 220 ℃. Meanwhile, the modulus of DEBAM cured material is higher than that of E51 cured material before 150 ℃, and the storage modulus of TEBAM cured material is still 1408MPa (single cantilever mode) at 200 ℃. Reflecting that the cured TEBAM and DETDA of example 2 of the present invention also have excellent thermo-mechanical properties.

Experimental example 3 thermal residual weight of cured synthetic resin

1. Experimental method

Thermogravimetric analysis (TGA) was performed on the cured resin of examples 1 and 2 and the cured resin of comparative example 1 at 800 ℃ in a nitrogen atmosphere.

2. Results of the experiment

As shown in fig. 3. It can be seen that the residual carbon content of E51 is only 11.8% at 800 ℃ under a nitrogen atmosphere. Under the same condition, the residual carbon content of DEBAM and TEBAM cured products can reach 18.5 percent and 25.2 percent, which shows that the resin has better heat resistance and ablation resistance than E51.

In conclusion, the invention provides a polar epoxy resin monomer with a typical structure and a curing system thereof. The polar epoxy resin monomer has high reaction activity, and an epoxy resin condensate obtained by the reaction of the polar epoxy resin monomer and a curing agent has high modulus and good thermomechanical property. The preparation method has important application value in the fields of rapid manufacturing of high-performance fiber reinforced thermosetting polymer composite materials, resin 3D printing and the like.

Claims (10)

1. An epoxy resin curing system is characterized by comprising an epoxy resin monomer containing a structure shown in a formula I and a curing agent:

wherein R is ₁ 、R ₂ 、R ₃ Each independently selected from hydrogen or

And R is ₁ 、R ₂ 、R ₃ At least one of which is

2. The epoxy curing system of claim 1, wherein the structure of formula I is:

3. the epoxy curing system of claim 1, wherein the curing agent is an amine curing agent, an anhydride curing agent, or an accelerator curing agent, and the amine curing agent is m-phenylenediamine, a halogen substituted or unsubstituted diaminodiphenylmethane, 3,4' -diaminodiphenylsulfone, diethyltoluenediamine, or diaminopyridine; the acid anhydride curing agent is methyl nadic anhydride or phthalic anhydride; the accelerator curing agent is 1-methylimidazole or 2-ethyl-4-methylimidazole.

4. The epoxy curing system of claim 3, wherein the curing agent is an amine curing agent, preferably a halogen substituted or unsubstituted diaminodiphenylmethane, more preferably 3,3 '-dichloro-4, 4' -diaminodiphenylmethane or diethyltoluenediamine.

5. The epoxy resin curing system of claim 4, wherein the molar ratio of active hydrogen of the amine-based curing agent to epoxy groups of the epoxy resin monomer is (0.8-2): 1, preferably 1.

6. The epoxy curing system of claim 1, further comprising a diluent; the diluent is styrene oxide, phenyl glycidyl ether, resorcinol glycidyl ether or hydroquinone glycidyl ether, preferably styrene oxide;

preferably, the diluent is used in an amount of 5% to 10% w/w of the epoxy resin curing system.

7. A cured epoxy resin which is obtained by reacting the epoxy resin curing system according to any one of claims 1 to 6 at 130 to 140 ℃ for 2 to 5 hours and then at 170 to 190 ℃ for 2 to 5 hours.

8. Use of the cured epoxy resin according to claim 7 as a matrix for composite materials or as a 3D printing material.

9. An epoxy resin monomer, characterized in that it comprises the following structure:

10. the method of preparing an epoxy resin monomer according to claim 9, comprising the steps of:

(1) Under the action of catalyst, the epoxy halopropane and saligenin react for 4-12 hours at 90-110 ℃;

(2) Cooling to below 70 ℃, adding alkali for reaction for 4-12 hours, cooling, filtering, standing for layering, and removing the catalyst and epihalohydrin in the supernatant to obtain the catalyst;

preferably, the epihalohydrin of step (1) is epichlorohydrin; the catalyst is benzyltriethylammonium bromide or 1-methylimidazole; and/or the base of step (2) is sodium hydroxide.

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