Novel modified tertiary amine latent epoxy curing accelerator as well as preparation method and application thereof

Abstract

The invention provides a novel modified tertiary amine latent epoxy curing accelerator as well as a preparation method and application thereof, and belongs to the technical field of fine chemical engineering new material auxiliary additives. The raw materials adopted by the method are simple and easy to obtain, the preparation process is simple and feasible, no organic solvent exists, safety and environment friendliness are achieved, the preparation cost is low, the prepared novel modified tertiary amine latent epoxy curing accelerator is solid at normal temperature and convenient to store and transport, the long storage life of a dicyandiamide / epoxy single-component curing system can be achieved, and the curing effect is good. And meanwhile, the requirement of a rapid curing process can be met at low temperature.

Description

Technical Field

[0001] The invention relates to a novel modified tertiary amine latent epoxy curing accelerator, a preparation method and application thereof, and belongs to the technical field of auxiliary additives for fine chemical new materials. Background Art

[0002] Epoxy resins have excellent chemical and mechanical properties and are widely used in different industrial fields, such as coatings, adhesives and composite materials. Some of these applications, such as prepreg manufacturing, require a one-component epoxy resin curing system based on a latent curing agent. At present, prepreg epoxy resins generally use dicyandiamide as a curing agent. However, dicyandiamide cannot react directly with epoxy resin at room temperature, and the curing reaction requires a higher temperature and a longer time. In order to shorten the curing reaction time, save energy consumption and improve efficiency, it is often necessary to add a curing accelerator to the dicyandiamide / epoxy system, but this also shortens the storage time of the one-component epoxy resin system. Most of the current commercial prepregs cannot be stored at ambient temperature and have a short shelf life. Moreover, most of them have a higher curing temperature and a longer curing process. Therefore, in all one-component epoxy resin systems, it is a real challenge to achieve both a long storage life and a low-temperature fast curing process.

[0003] Common dicyandiamide latent curing agents include dicyandiamide and its derivatives, urea derivatives, tertiary amines, quaternary ammonium salts, etc. Among them, tertiary amines have the most obvious accelerator effect, which can enable the dicyandiamide / epoxy system to achieve low-temperature rapid curing. However, when tertiary amines are used as accelerators, since tertiary amines are liquid at room temperature, they can induce the self-polymerization reaction of epoxy resin at room temperature, so the storage period of the single-component epoxy resin system is extremely short.

[0004] Therefore, there is an urgent need in the art for a novel modified tertiary amine latent epoxy curing accelerator that allows a one-component epoxy resin system to have a longer shelf life, and a preparation method and application thereof. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of extremely short storage period of single-component epoxy resin system in the prior art.

[0006] In order to achieve the purpose of solving the above problems, the technical solution adopted by the present invention is to provide a novel modified tertiary amine latent epoxy curing accelerator, a preparation method and application thereof.

[0007] The first aspect of the present invention provides a novel modified tertiary amine latent epoxy curing accelerator, the chemical structure of which is:

[0008]

[0009] In the formula, R1 is a benzene ring or a methylene group, and R2 is bisphenol A or a methyl group.

[0010] The second aspect of the present invention provides a method for preparing the novel modified tertiary amine latent epoxy curing accelerator, comprising the following steps:

[0011] Step 1: Prepare the raw materials:

[0012] Tertiary amine 20-40%;

[0013] Acid anhydride 20-40%;

[0014] Epoxy resin composition 30-50%;

[0015] Among them, each component is counted by mass percentage;

[0016] Step 2, adding anhydride into a reaction vessel, installing a condensation reflux device, heating, and adding the epoxy resin composition after the anhydride is completely melted into liquid;

[0017] Step 3: Stir, add tertiary amine in small amounts and repeatedly, and heat statically to obtain a solid product;

[0018] Step 4: Put the solid product obtained in step 3 into a vacuum drying oven, dry it, and grind it with a mortar to obtain a novel modified tertiary amine latent epoxy curing accelerator.

[0019] Preferably, in step 1, the tertiary amine is selected from one or more of 2,4,6-tris(dimethylaminomethyl)phenol, o-hydroxybenzyldimethylamine and N,N-dimethylethanolamine.

[0020] Preferably, in step 1, the acid anhydride comprises one or more of phthalic anhydride, 4-methylphthalic anhydride, methyltetrahydrophthalic anhydride and hexahydrophthalic anhydride.

[0021] Preferably, in step 1, the epoxy resin composition comprises C 12 ~C 14 One or more of monofunctional glycidyl ether, bisphenol A type glycidyl ether and aliphatic glycidyl ether.

[0022] Preferably, in step 2, the heating temperature is 40°C to 70°C.

[0023] Preferably, in step 3, the stirring time is 0.5 h and the static heating temperature is 100° C.

[0024] Preferably, in step 4, the drying temperature is 40° C. to 60° C., and the drying time is 0.5 to 3 hours.

[0025] The mechanism adopted by the preparation method is that the phenolic hydroxyl group / alcoholic hydroxyl group in the tertiary amine can combine with the epoxide to form a hydrogen bond, thereby forming an epoxy-hydroxyl intermediate. In the next step, the activated intermediate attacks the anhydride, resulting in the ring-opening esterification of the anhydride to obtain a new modified tertiary amine. The new modified tertiary amine has a higher melting point than the tertiary amine, and is solid at room temperature. When used as a promoter, it has a long storage life at room temperature. When the temperature is higher than its melting point, the new modified tertiary amine has a high-efficiency promotion effect similar to that of the tertiary amine after melting, achieving the requirements of the rapid curing process of the one-component epoxy system.

[0026] The third aspect of the present invention provides a use of the novel modified tertiary amine latent epoxy curing accelerator in a dicyandiamide / epoxy one-component curing system.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The raw materials used in the method of the invention are simple and easy to obtain, the preparation process is simple and feasible, there is no organic solvent, it is safe and environmentally friendly, and the preparation cost is low.

[0029] The novel modified tertiary amine latent epoxy curing accelerator prepared by the invention is solid at room temperature and is convenient for storage and transportation.

[0030] The novel modified tertiary amine latent epoxy curing agent prepared by the invention can realize a long storage life of a dicyandiamide / epoxy single-component curing system and can also meet the requirements of a fast curing process at low temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the infrared spectrum of the new modified tertiary amine latent epoxy curing accelerator;

[0032] Figure 2 This is the DSC spectrum of a one-component epoxy resin system cured with a new type of modified tertiary amine latent epoxy curing accelerator. DETAILED DESCRIPTION

[0033] In order to make the present invention more clearly understood, a preferred embodiment is described in detail with reference to the accompanying drawings as follows:

[0034] like Figure 1-2 As shown, the present invention provides a novel modified tertiary amine latent epoxy curing accelerator, a preparation method and application thereof.

[0035] Example 1

[0036] Step 1) 15 g of methyltetrahydrophthalic anhydride and 10 g of phthalic anhydride were placed in a single-necked flask, a condensing reflux device was installed, and the mixture was heated to 60° C.;

[0037] Step 2) After the acid anhydride is completely melted into liquid, 30 g of bisphenol A glycidyl ether is added, and the mixture is stirred for reaction for 0.5 h, and then 26 g of 2,4,6-tris(dimethylaminomethyl)phenol is added in small amounts and several times, and the mixture is stirred for reaction for 0.5 h, and then heated at 100° C. for 2 h;

[0038] Step 3) placing the solid product in a vacuum drying oven, drying at 40° C. for 1 h, and grinding it in a mortar to obtain a novel modified tertiary amine latent epoxy curing accelerator.

[0039] The obtained product was subjected to infrared analysis, and the DSC spectrum after the test was as follows Figure 1 Of which 1775cm -1 1715cm -1 The broad band at 1731cm -1 A new C=O stretching band of the ester group appears at , indicating that the anhydride is completely consumed by the epoxyhydroxy intermediate to form a new modified tertiary amine.

[0040] The obtained product was subjected to DSC analysis under the following test conditions: heating from 0°C to 250°C at a heating rate of 10K / min. The DSC spectrum after the test is shown in Figure 2 As shown, there is an obvious glass transition peak, indicating that the glass transition temperature of the solid product synthesized in Example 1 is above 100°C.

[0041] Example 2

[0042] This embodiment is substantially the same as embodiment 1, except that 24 g of tetrahydrophthalic anhydride is used for the reaction.

[0043] Example 3

[0044] This example is substantially the same as Example 1, except that 20 g of o-hydroxybenzyldimethylamine is used for the reaction.

[0045] Test cases 1 to 3

[0046] After 2 g of the modified tertiary amine latent epoxy curing accelerator obtained in Examples 1 to 3, 100 g of E51 epoxy resin, and 10 g of dicyandiamide were uniformly mixed, the gel time of the mixed glue was tested at 120° C., 130° C., 140° C., and 150° C., respectively, and the storage period of the mixed glue was tested at 40° C. (viscosity doubling time at 40° C.),

[0047] Comparative Example 1

[0048] The method is basically the same as Test Examples 1 to 3, except that the curing accelerator is replaced with urea derivative UR400.

[0049] The test results are shown in Table 1

[0050]

[0051]

[0052] The above tests show that the novel modified tertiary amine latent epoxy curing accelerator synthesized by the present invention has a long storage period at room temperature after being mixed with epoxy resin, and can achieve rapid gelation within 5 minutes at a temperature of 120°C, which can achieve a long storage life of the dicyandiamide / epoxy single-component curing system and at the same time meet the requirements of the rapid curing process at low temperatures.

[0053] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A novel modified tertiary amine latent epoxy curing accelerator, characterized in that: Its chemical structure is: In the formula, R1 is a benzene ring or a methylene group, and R2 is bisphenol A or a methyl group.

2. A method for preparing the novel modified tertiary amine latent epoxy curing accelerator as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Prepare the ingredients: Tertiary amine 20-40%; Acid anhydride 20-40%; Epoxy resin composition 30-50%; Among them, each component is counted by mass percentage; Step 2, adding anhydride into a reaction vessel, installing a condensation reflux device, heating, and adding the epoxy resin composition after the anhydride is completely melted into liquid; Step 3: Stir, add tertiary amine in small amounts and repeatedly, and heat statically to obtain a solid product; Step 4: Put the solid product obtained in step 3 into a vacuum drying oven, dry it, and grind it with a mortar to obtain a novel modified tertiary amine latent epoxy curing accelerator.

3. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 1, the tertiary amine is selected from one or more of 2,4,6-tris(dimethylaminomethyl)phenol, o-hydroxybenzyldimethylamine and N,N-dimethylethanolamine.

4. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 1, the acid anhydride includes one or more of phthalic anhydride, 4-methylphthalic anhydride, methyltetrahydrophthalic anhydride and hexahydrophthalic anhydride.

5. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 1, the epoxy resin composition comprises C 12 ~C 14 One or more of monofunctional glycidyl ether, bisphenol A type glycidyl ether and aliphatic glycidyl ether.

6. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 2, the heating temperature is 40°C to 70°C.

7. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 3, the stirring time is 0.5 h and the static heating temperature is 100° C.

8. The method for preparing the novel modified tertiary amine latent epoxy curing accelerator according to claim 2, characterized in that: In the step 4, the drying temperature is 40° C. to 60° C., and the drying time is 0.5 to 3 hours.

9. Use of the novel modified tertiary amine latent epoxy curing accelerator as claimed in claim 1 in a dicyandiamide / epoxy one-component curing system.

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