Preparation method of toughened polyurethane film

Abstract

The invention provides a kind of preparation method of toughened polyurethane film, comprises the following steps: S1, the preparation of film casting liquid; The solvent of dimethylformamide is blended into a ternary mixed solvent; then the polyurethane prepolymer and the ternary mixed solvent are uniformly stirred by a machine, and then vacuum defoamed to prepare a polyurethane casting solution; S2, coagulation bath preparation; S3, the polyurethane The casting solution is scraped and coated on the mold; S4, the mold is heat-treated at 40-80°C for 30-60s; S5, the mold is subjected to immersion precipitation and solvent evaporation treatment in sequence; S6, the polyurethane film is treated at 80-100°C Heat treatment to obtain a toughened polyurethane film. The present invention adopts the poor solvent of polyurethane, N, N-dimethylformamide and the solvent with polarity lower than N, N-dimethylformamide to mix into a ternary mixed solvent system to improve the polyurethane film-forming rate and polyurethane molecules The arrangement of the chains can obtain a polyurethane film with excellent mechanical properties.

Description

technical field [0001] The invention relates to the technical field of polymer film preparation, in particular to a method for preparing a toughened polyurethane film. Background technique [0002] Polyurethane is a block polymer composed of alternating soft and hard segments. The soft segment is in a highly elastic state at room temperature and can produce large tensile deformation, while the hard segment provides nodes for the elongation and deformation of the soft segment. The unique chemical structure of polyurethane makes it have excellent properties such as high elasticity, abrasion resistance, solvent resistance, water resistance, fatigue resistance and aging resistance, so it is widely used in textile, national defense, transportation, sports, construction, medical, Fields such as machinery and energy occupy a very important position in the national economy. [0003] At present, the commonly used methods for preparing high-tough polyurethane films include chemical m...

AI Technical Summary

Problems solved by technology

Although this method uses ammonium salt as a coagulation bath, the micro-crosslinked structure formed in the form of hydrogen bonds between the ammonium salt molecules in the polyurethane film after film formation and the amorphous region molecules in the polyurethane, or in the pores of the polyurethane film The formation of nano-needle structure and nano-spherical structure can increase the tensile stress and strain of the polyurethane film at the same time, but its disadvantage is that on the one hand, the toughening range of the polyurethane film prepared by this method is not large enough; The polyurethane film prepared by the method introduces the second phase material, not a single-component pure polyurethane film

However, its shortcoming is that the toughening effect of this method on polyurethane is not significant enough, and the film-making method adopted in this article does not give full play to the excellent structure and performance of polyurethane bulk material

[0009] The public doctoral thesis "Research on the Phase Transformation Control Mechanism and Performance of High Tough Polyurethane and Its Composite Materials" was published in April 2018. In this doctoral thesis, different proportions of N,N-dimethylformamide and toluene were used as mixed solvents. The polyurethane film has been prepared, although it uses a binary mixed solvent of different components to toughen the polyurethane, but its disadvantage is that this method has no effect on the toughening of the polyurethane film while improving the elongation at break of the polyurethane. Significantly, no greater limit for toughened polyurethane membranes

Images