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Preparation method of toughened polyurethane film

A polyurethane film and polyurethane technology, applied in the field of toughening polyurethane film preparation, can solve the problem that the polyurethane toughening effect is not significant enough, the structure and performance of the polyurethane body material are not fully exerted, and the polyurethane elongation at break The toughening effect of the polyurethane film is not very good. Significant other issues

Active Publication Date: 2021-11-19
WUHAN TEXTILE UNIV
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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

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  • Preparation method of toughened polyurethane film
  • Preparation method of toughened polyurethane film
  • Preparation method of toughened polyurethane film

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preparation example Construction

[0037] see figure 1 Shown, the invention provides a kind of preparation method of toughened polyurethane film, comprises the following steps:

[0038] S1, the preparation of film casting solution; mix the poor solvent of polyurethane, N, N-dimethylformamide and the solvent with polarity lower than N, N-dimethylformamide into a ternary mixed solvent, wherein, the polyurethane The mass fraction of poor solvent is 5% to 45%; the mass fraction of N, N-dimethylformamide is 30% to 90%; the mass fraction of solvents with lower polarity than N, N-dimethylformamide is 5% to 30%;

[0039] Then the polyurethane prepolymer and ternary mixed solvent with a mass fraction ratio of 5%: 95% to 40%: 60% are uniformly stirred mechanically and then vacuum defoamed to prepare polyurethane casting liquid; wherein, the stirring temperature is 20 to 45 ℃, the stirring rate is 500~4000r / min, and the stirring time is 0.5~5h;

[0040] S2, coagulation bath preparation;

[0041] S3, scraping and coati...

Embodiment 1

[0055] The mass fraction ratio is 5%: 85%: 10% toluene, N, N-dimethylformamide and dioxane are blended into a ternary mixed solvent, and then the mass fraction ratio is 10%: 90% Polyether polyurethane prepolymer and ternary mixed solvent were mechanically stirred for 2 hours, and then vacuum defoamed to prepare polyurethane casting solution. Wherein, the stirring temperature is 30° C., and the stirring rate is 800 r / min.

[0056] The mass fraction ratio is 99%: 1% deionized water and ethanol are compounded, stirred evenly and then prepared into a coagulation bath. Wherein, the conductivity of the deionized water is 16MΩ·cm, and the temperature of the coagulation bath solution is 20°C.

[0057] Scrape-coat the prepared polyurethane casting solution on the polytetrafluoroethylene mold, immediately immerse in the coagulation bath for 4 hours after heat treatment for 60 seconds, take it out, and then place it in a 30°C drying oven for solvent evaporation treatment for 48 hours, a...

Embodiment 2 Embodiment 8

[0063] The difference between embodiment two to embodiment eight and embodiment one is only: in the ternary mixed solvent, the mass fraction ratio of toluene, N,N-dimethylformamide and dioxane is different, and other steps are the same as in embodiment one are basically the same, and are not repeated here; the mass fractions of toluene, N, N-dimethylformamide and dioxane in embodiment two to embodiment eight are as shown in the following table:

[0064]

[0065] The process of preparing polyurethane film by traditional immersion precipitation method is: the preparation of casting solution; dissolving polyurethane in N, N-dimethylformamide, stirring uniformly after mechanical stirring, vacuum defoaming and preparing polyurethane casting solution; The casting solution is scraped and coated on the mold, and then the mold containing the casting solution is immersed in a water coagulation bath for about 2 hours, and then the mold is taken out and dried to obtain a polyurethane fi...

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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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J5/18C08L75/04
CPCC08J5/18C08J2375/04
Inventor 刘欣张春华王云吕佩李晨张科徐卫林
Owner WUHAN TEXTILE UNIV
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