A light specific gravity epoxy foaming resin and preparation method thereof

Abstract

The present invention relates to the technical field of resins for prepregs, and in particular to a light specific gravity epoxy foaming resin and a preparation method thereof. The light specific gravity epoxy foaming resin comprises the following raw materials: bisphenol A type epoxy resin, bisphenol F type epoxy resin, epoxy toughening agent, phenolic epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent, so as to ensure the adhesion between the light specific gravity epoxy foaming resin and the carbon fiber prepreg adopted by the present invention, avoid easy separation and cracking after being bonded with the carbon fiber prepreg and seriously affect the product quality, promote the light specific gravity epoxy foaming resin to retain the connection stability, crack resistance and bending strength after being bonded with the carbon fiber prepreg, self-foaming at a temperature of 140-160°C can increase the volume by 5-10 times, and compared with the traditional resin matrix, the density of the light specific gravity epoxy foaming resin after curing is smaller, and the flame retardancy reaches V-0 level.

Description

Technical Field

[0001] The invention relates to the technical field of resins for prepregs, and in particular to a light specific gravity epoxy foaming resin and a preparation method thereof. Background Art

[0002] Carbon fiber prepreg is made by compounding epoxy resin on carbon fiber through high pressure and high temperature technology. The composite material made of carbon fiber yarn, epoxy resin, release paper and other materials through coating, hot pressing, cooling, laminating, winding and other processes is called carbon fiber prepreg, also known as carbon fiber prepreg. It is called prepreg because it is only the initial impregnation of resin and carbon fiber, and the final impregnation is when the product is formed.

[0003] When the product is finally impregnated, most of the existing resin matrices use epoxy resin, but its density is relatively high, and the obtained products, especially the carbon fiber prepreg cloth, are not conducive to lightweight after the final impregnation; if lighter PU or PVC resin is used as the resin matrix for the final impregnation, its weight reduction effect is not large, and it is easy to separate and crack after being connected with the carbon fiber prepreg cloth, which seriously affects the product quality. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the object of the present invention is to provide a light specific gravity epoxy foaming resin.

[0005] Another object of the present invention is to provide a method for preparing a light specific gravity epoxy foaming resin, which has simple operation, convenient control, high production efficiency, low production cost, and can be used for large-scale production.

[0006] The purpose of the present invention is achieved through the following technical solution: A light specific gravity epoxy foaming resin comprises the following raw materials in parts by weight:

[0007] 30-50 parts of bisphenol A epoxy resin

[0008] 30-50 parts of bisphenol F epoxy resin

[0009] Epoxy toughening agent 10-20 parts

[0010] 5-10 parts of phenolic epoxy resin

[0011] 5-10 parts of latent curing agent

[0012]

[0013] The light specific gravity epoxy foaming resin of the present invention uses bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin as main resins. The mixture of the three has higher crystallization resistance. The light specific gravity epoxy foaming resin has highly similar compatibility with the epoxy resin contained in the carbon fiber prepreg itself, so as to ensure the adhesion between the light specific gravity epoxy foaming resin used in the present invention and the carbon fiber prepreg, avoid easy separation and cracking after bonding with the carbon fiber prepreg, and seriously affect the product quality. Epoxy toughening agent, latent curing agent, curing accelerator, flame retardant powder and foaming agent are added to promote the light specific gravity epoxy foaming resin to retain the connection stability, crack resistance and bending strength after bonding with the carbon fiber prepreg. Self-foaming at a temperature of 140-160°C can increase the volume by 5-10 times. Compared with the traditional resin matrix, the density of the light specific gravity epoxy foaming resin after curing is smaller, and the flame retardancy reaches V-0 level.

[0014] Preferably, the bisphenol A epoxy resin is at least one of E20, E44 and E51; the bisphenol F epoxy resin is at least one of EPIKOTE862, YDF-162 and NPEF-170.

[0015] By adopting the above technical scheme, the above bisphenol A epoxy resin undergoes a cross-linking reaction with a latent curing agent and a curing accelerator to form an insoluble polymer with a three-dimensional network structure, which has high strength and bonding strength, and has certain toughness and heat resistance. By adopting the above bisphenol F epoxy resin, the overall viscosity of the light specific gravity epoxy foaming resin is reduced, the wetting properties of the flame retardant powder and the foaming agent are improved, the impregnation properties are improved, and the crystallization resistance and heat resistance are higher when blended with bisphenol A epoxy resin and phenolic epoxy resin.

[0016] Preferably, the epoxy toughening agent is at least one of PA662, DY-040 and FORTEGRA100.

[0017] By adopting the above technical scheme, reacting with bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic epoxy resin and curing agent, the proportion of flexible network in the bulk cross-linked structure is increased, thereby improving the flexibility of epoxy cured product, reducing internal stress, and significantly improving the product's crack resistance and temperature shock resistance.

[0018] Preferably, the phenolic epoxy resin is F-51, F-44 or F-48.

[0019] By adopting the above technical solution, the added phenolic epoxy resin and bisphenol A epoxy resin work together to improve the overall strength.

[0020] Preferably, the latent curing agent is a mixture of dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:1-2, and the curing accelerator is an imidazole accelerator.

[0021] By adopting the above technical solution, the latent curing agent cooperates with the curing accelerator, and the light specific gravity epoxy foaming resin completes curing while self-foaming at a temperature of 140-160°C.

[0022] More preferably, the imidazole accelerator is at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole and N-methylimidazole.

[0023] Preferably, the flame retardant powder has a chemical structure as shown in Formula I:

[0024]

[0025] Wherein, R1 is an aryl group, R2 is a C1-C12 alkyl group, X is an alkyl group, an aryl group, an alkenyl group, hydrogen, a hydroxyl group, an alkoxy group or an acetoxy group, m=3-100, and n=1-100.

[0026] By adopting the above technical scheme, the compatibility with epoxy resin is good, avoiding adverse effects on the adhesion and crack resistance of the light specific gravity epoxy foaming resin, and the flame retardant effect itself is good. When a fire occurs, the flame retardant powder can migrate from the inside of the plastic to the surface, and form a homogeneous flame retardant layer on the surface by compounding with the carbide of the plastic; the main chain contains a unique branched structure, and the stability of its chemical bonds and the characteristics of its molecular structure can improve the heat resistance of the flame retardant powder, thereby achieving a V-0 flame retardant effect based on a lower dosage.

[0027] Preferably, the foaming agent is expandable microspheres.

[0028] The above technical solution is adopted to facilitate the self-foaming of the light specific gravity epoxy foaming resin at a temperature of 140-160° C. More preferably, the foaming agent is expandable microsphere LH-150.

[0029] Another object of the present invention is achieved by the following technical solution: The preparation method of the above-mentioned light specific gravity epoxy foaming resin comprises the following steps:

[0030] (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside;

[0031] (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture;

[0032] (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 50-60° C. for 1-2 hours to obtain a light specific gravity epoxy foaming resin.

[0033] The beneficial effects of the present invention are as follows: the light specific gravity epoxy foaming resin of the present invention uses bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin as main resins, and the mixture of the three has higher crystallization resistance, and has highly similar compatibility with the epoxy resin contained in the carbon fiber prepreg itself, so as to ensure the adhesion between the light specific gravity epoxy foaming resin used in the present invention and the carbon fiber prepreg, avoid easy separation and cracking after bonding with the carbon fiber prepreg, and seriously affect the product quality; epoxy toughening agent, latent curing agent, curing accelerator, flame retardant powder and foaming agent are added to promote the light specific gravity epoxy foaming resin to retain the connection stability, crack resistance and bending strength after bonding with the carbon fiber prepreg; self-foaming at a temperature of 140-160°C can increase the volume by 5-10 times; compared with the traditional resin matrix, the density of the light specific gravity epoxy foaming resin after curing is smaller, and the flame retardancy reaches V-0 level.

[0034] The preparation method of the invention has the advantages of simple operation, convenient control, high production efficiency and low production cost, and can be used for large-scale production. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0036] Example 1

[0037] A light specific gravity epoxy foaming resin comprises the following raw materials in parts by weight:

[0038] 40 parts of bisphenol A epoxy resin

[0039]

[0040] The bisphenol A type epoxy resin is E44; the bisphenol F type epoxy resin is EPIKOTE862.

[0041] The epoxy toughening agent is a mixture of PA662, DY-040 and FORTEGRA100 in a weight ratio of 2:1:1.

[0042] The phenolic epoxy resin is F-51.

[0043] The latent curing agent is a mixture of dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:1.5.

[0044] The curing accelerator is 2-methylimidazole.

[0045] The flame retardant powder has a chemical structure as shown in Formula I:

[0046]

[0047] Wherein, R1 is phenyl, R2 is isopropyl, X is methyl, m=30, and n=20.

[0048] The foaming agent is expandable microsphere LH-150.

[0049] The preparation method of the light specific gravity epoxy foaming resin comprises the following steps:

[0050] (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside;

[0051] (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture;

[0052] (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 55° C. for 1.5 hours to obtain a light specific gravity epoxy foaming resin.

[0053] Example 2

[0054] A light specific gravity epoxy foaming resin comprises the following raw materials in parts by weight:

[0055]

[0056] The bisphenol A type epoxy resin is E51; the bisphenol F type epoxy resin is YDF-162.

[0057] The epoxy toughening agent is a mixture of PA662, DY-040 and FORTEGRA100 in a weight ratio of 1:1:1.

[0058] The phenolic epoxy resin is F-51.

[0059] The latent curing agent is a mixture of dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:1.

[0060] The curing accelerator is 2-ethyl-4-methylimidazole.

[0061] The flame retardant powder has a chemical structure as shown in Formula I:

[0062]

[0063] Wherein, R1 is phenyl, R2 is isopropyl, X is hydroxyl, m=30, and n=20.

[0064] The foaming agent is expandable microsphere LH-150.

[0065] The preparation method of the light specific gravity epoxy foaming resin comprises the following steps:

[0066] (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside;

[0067] (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture;

[0068] (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 50° C. for 1 hour to obtain a light specific gravity epoxy foaming resin.

[0069] Example 3

[0070] A light specific gravity epoxy foaming resin comprises the following raw materials in parts by weight:

[0071]

[0072] The bisphenol A epoxy resin is E51; the bisphenol F epoxy resin is NPEF-170.

[0073] The epoxy toughening agent is a mixture of PA662, DY-040 and FORTEGRA100 in a weight ratio of 4:1:1.

[0074] The phenolic epoxy resin is F-51.

[0075] The latent curing agent is a mixture of dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:2.

[0076] The curing accelerator is N-methylimidazole.

[0077] The flame retardant powder has a chemical structure as shown in Formula I:

[0078]

[0079] Wherein, R1 is phenyl, R2 is isopropyl, X is acetoxy, m=30, n=20.

[0080] The foaming agent is expandable microsphere LH-150.

[0081] The preparation method of the light specific gravity epoxy foaming resin comprises the following steps:

[0082] (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside;

[0083] (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture;

[0084] (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 60° C. for 2 hours to obtain a light specific gravity epoxy foaming resin.

[0085] Example 4

[0086] A light specific gravity epoxy foaming resin comprises the following raw materials in parts by weight:

[0087]

[0088] The bisphenol A type epoxy resin is E20; the bisphenol F type epoxy resin is EPIKOTE862.

[0089] The epoxy toughening agent is a mixture of PA662, DY-040 and FORTEGRA100 in a weight ratio of 2.5:1:1.

[0090] The phenolic epoxy resin is F-48.

[0091] The latent curing agent is a mixture of dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:1.8.

[0092] The curing accelerator is 2-ethyl-4-methylimidazole.

[0093] The flame retardant powder has a chemical structure as shown in Formula I:

[0094]

[0095] Wherein, R1 is phenyl, R2 is isopropyl, X is alkoxy, m=30, n=20.

[0096] The foaming agent is expandable microsphere LH-150.

[0097] The preparation method of the light specific gravity epoxy foaming resin comprises the following steps:

[0098] (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside;

[0099] (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture;

[0100] (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 58° C. for 1.2 hours to obtain a light specific gravity epoxy foaming resin.

[0101] Comparative Example 1

[0102] The difference between this comparative example and Example 1 is:

[0103] In the light specific gravity epoxy foaming resin, the weight amount of the bisphenol A epoxy resin is 80 parts, and no bisphenol F epoxy resin is contained.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 1 is:

[0106] The light specific gravity epoxy foaming resin does not contain a foaming agent.

[0107] Comparative Example 3

[0108] The difference between this comparative example and Example 1 is:

[0109] The flame retardant powder is organic silicon flame retardant X-40-9805.

[0110] Comparative Example 4

[0111] The difference between this comparative example and Example 1 is:

[0112] The epoxy toughening agent is PA662.

[0113] Example 5

[0114] The light specific gravity epoxy foaming resins of Examples 1-4 and Comparative Examples 1-4 were taken to test their density, bending strength, flame retardant grade and adhesion to carbon fiber prepreg after curing at 150° C. The test results are shown in the following table:

[0115]

[0116]

[0117] As can be seen from the above table, the light specific gravity epoxy foaming resin of the present invention uses bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin as the main resins. The mixture of the three has higher anti-crystallization property. It has a highly similar compatibility with the epoxy resin contained in the carbon fiber prepreg itself, so as to ensure the adhesion between the light specific gravity epoxy foaming resin used in the present invention and the carbon fiber prepreg, and avoid easy separation and cracking after bonding with the carbon fiber prepreg, which seriously affects the product quality. Epoxy toughening agent, latent curing agent, curing accelerator, flame retardant powder and foaming agent are added to promote the light specific gravity epoxy foaming resin to retain the connection stability, crack resistance and bending strength after bonding with the carbon fiber prepreg. Self-foaming at a temperature of 140-160°C can increase the volume by 5-10 times. Compared with the traditional resin matrix, the density of the light specific gravity epoxy foaming resin after curing is smaller, and the flame retardancy reaches V-0 level.

[0118] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A light specific gravity epoxy foaming resin, characterized in that: The invention comprises the following raw materials in parts by weight: The foaming agent is expandable microsphere LH-150; The epoxy toughening agent is a mixture of PA662, DY-040 and FORTEGRA 100 in a weight ratio of (1, 2, 2.5 or 4): 1:1; The flame retardant powder has a chemical structure as shown in Formula I: Wherein, R1 is an aryl group, R2 is a C1-C12 alkyl group, X is an alkyl group, an aryl group, an alkenyl group, hydrogen, a hydroxyl group, an alkoxy group or an acetoxy group, m=3-100, and n=1-100.

2. The light specific gravity epoxy foam resin according to claim 1, characterized in that: The bisphenol A type epoxy resin is at least one of E20, E44 and E51; the bisphenol F type epoxy resin is at least one of EPIKOTE 862, YDF-162 and NPEF-170.

3. The light specific gravity epoxy foaming resin according to claim 1, characterized in that: The phenolic epoxy resin is F-51, F-44 or F-48.

4. The light specific gravity epoxy foaming resin according to claim 1, characterized in that: The latent curing agent is prepared by mixing dicyandiamide and boron trifluoride ethylamine complex in a weight ratio of 3:1-2.

5. The light specific gravity epoxy foaming resin according to claim 1, characterized in that: The curing accelerator is an imidazole accelerator.

6. The light specific gravity epoxy foaming resin according to claim 5, characterized in that: The imidazole accelerator is at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole and N-methylimidazole.

7. A method for preparing a light specific gravity epoxy foaming resin as claimed in any one of claims 1 to 6, characterized in that: The steps include: (1) Take bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin, latent curing agent, curing accelerator, flame retardant powder and foaming agent by weight and set aside; (2) Stirring bisphenol A epoxy resin, bisphenol F epoxy resin, epoxy toughening agent, novolac epoxy resin and flame retardant powder at room temperature for 1 hour to obtain a mixture; (3) Stir the mixture, latent curing agent, curing accelerator and foaming agent at 50-60° C. for 1-2 hours to obtain a light specific gravity epoxy foaming resin.

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