Development of Polyurethane Modified Epoxy Adhesive

FIG. 11 is an SEM photograph (5000 times) of a curved fracture surface after curing with MDA when M2/MDI system was used, and the prepolymer was added in amounts of 10, 30, 50, 70, and 100 parts, respectively. FIG. As can be seen from the photographs, with the increase of the amount of prepolymer added, the morphology of the fracture surface of the modified system has changed significantly. When the amount of prepolymer added was 10 parts, the cross section was smooth and smooth, and it was difficult to see the pores after the rubber particles were broken out. It can be seen that the fractured form at this time is still brittle fracture. When the amount of prepolymer added was 30 parts, the surface of the cross-section was rough, and the interpenetration between the two sections was very obvious, and it could be observed that part of the rubber particles with a diameter of about 0.5 μm left after leaving the hole-like shape. In this case, it can be seen that the fracture at this time is ductile fracture. When the prepolymer is added in an amount of 50 parts, the surface of the cross section is rough, and a large number of 1-3 μm balls precipitate. It can be seen that the phase separation of the two phases is serious at this time; due to the continuous phase between the polyurethane rubber phase and the epoxy resin With chemical bonds, the precipitate may not only be the polyurethane rubber phase, otherwise it cannot be so much that the polyurethane rubber phase should contain a portion of the epoxy resin phase. When the amount of prepolymer added was 70 parts, the surface of the cross section was rough and the size of the precipitated spherical particles was reduced, which was about 0.5-1.5 μm. It can be seen that when the phase separation of the two phases is more than 50 parts, it has been improved. When the amount of prepolymer added was 100 parts, the surface of the cross section was rough, and the size of the precipitated spherical particles was further reduced, which was about 0.2-1 μm, and the phase separation of the two phases was further improved when compared with 70 parts.

With the increase of the amount of prepolymer added, the rubber particles continue to accumulate, and the modified system gradually transitions from homogeneous to two-phase, and the degree of phase separation continuously increases. When the degree of phase separation reaches a certain level, the two-phase phase separation is serious. The amount of prepolymer added continues to increase, the polyurethane rubber phase gradually shifts to a continuous phase, and the mutual solubility of the two phases is gradually improved.

4 Conclusion

1. Epoxy group after epoxy resin modification has not changed, the main body is still epoxy resin.

2. After the modification of epoxy resin, the toughness is improved, and the shear strength, peeling strength, and impact strength are greatly improved in a certain range.

3. With the increase of polyurethane content, the microscopic morphology has changed, which has led to changes in mechanical properties.

4, compared with CTBN, polyurethane modified epoxy resin has similar performance, but the cost is greatly reduced.

5, room temperature curing temperature curing agent A curing modified epoxy resin has excellent adhesive properties, good process performance, can be applied in a variety of occasions.

(Author/Zhang Bin, Sun Mingming, Zhang Xugang, Wang Chao, Li Qili, Guan Chang, Heilongjiang Institute of Petroleum Chemistry)

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