What are the factors that affect the tensile strength of BOPP synthetic paper?

The factors that affect the tensile strength of BOPP (biaxial tensile polypropylene) synthetic paper mainly include the following aspects:

1. Temperature

Viscous flow temperature (Tf) and melting point (Tm) : The production process and quality of BOPP tensile film are closely related to these two factors. Temperature affects the orientation process by affecting polymer viscosity and relaxation time. As the temperature increases, the polymer viscosity decreases, which is conducive to polymer orientation, but too high temperature will cause the molecular chain disorientation rate to accelerate, thus reducing the tensile strength.

Preheating and stretching temperature: too high preheating temperature will cause PP to form spherulite and reduce the film transparency; However, high tensile temperature will cause sticky roll of heat-sealing surface material, and greatly reduce the physical and mechanical properties of BOPP film. Therefore, choosing the right preheating and stretching temperature is very important to improve the tensile strength of BOPP synthetic paper.

2. Drawing rate

The tensile rate of BOPP films has a significant effect on the mechanical properties of the films. The faster the tensile rate, the tensile strength and tensile modulus of the film will generally increase, but the elongation at break will decrease. This is because when stretched at high speed, the movement of molecular chain segments cannot keep up with the speed of external force, and the plastic presents brittle behavior.

3. Raw material properties

The crystallinity, molecular weight distribution, additive type and content of raw polypropylene (PP) will affect the tensile strength of BOPP synthetic paper. For example, the addition of pore-causing agents will affect the crystal and amorphous structure of PP, thus affecting the performance of synthetic paper.

4. Production process parameters

In the production process of BOPP synthetic paper, in addition to temperature and drawing rate, other process parameters such as drawing ratio, cooling rate, roll surface temperature distribution, etc., will also affect the tensile strength. The optimization and adjustment of these parameters help to improve the overall performance of the synthetic paper.

5. Test environment

During the tensile test, environmental factors such as temperature, humidity and vibration will also affect the test results. Therefore, when testing the tensile strength of BOPP synthetic paper, it is necessary to ensure the stability and consistency of the test environment.

In summary, there are many factors affecting the tensile strength of BOPP synthetic paper, including temperature, tensile rate, raw material properties, production process parameters and test environment. In the actual production process, it is necessary to consider these factors comprehensively, and improve the tensile strength and other performance indicators of synthetic paper by optimizing the process parameters and test conditions.