By virtue of the strong winding force and retraction of the film, the product is tightly and fixedly bundled into a unit, even in an adverse environment, the product is not loose and separated. Therefore, the stretch film should have good puncture performance and transverse tearing strength to ensure that the film will not break when it encounters sharp objects at a high tensile ratio. Taking the stretch film as an example, this paper uses the XLW (EC) intelligent electronic tensile testing machine to test the anti-puncture force of the stretch film, in order to verify whether the stretch film can effectively resist the puncture of the angular angle of the goods, at the same time, the principle and procedure of the test are introduced, which can provide a reference for the industry to monitor the puncture performance of the stretch film.
The reason is that the stretch film produced by tape casting lines has the advantages of uniform thickness and high transparency, which can be applied to the requirement of high rate pre-drawing. Because single-layer tape casting can not achieve single-side viscosity, its application is limited, so its application is not as wide as three-layer tape process stretch film, and high-quality winding film should have high transparency, high longitudinal elongation, high yield point, high transverse tearing strength and good puncture performance.
Anti-puncture performance is a guiding index for evaluating the ability of packaging to resist the piercing of sharp hard objects. In the long-term contact with the packaging process, if the product contains more sharp hard material, easy to produce strong wound film puncture. If the anti-puncture performance of the stretch film is poor, easy to be punctured by sharp damage, resulting in products or goods loose separation, can not play a protective role. This is also the reason why stretch film packaging should have higher puncture resistance.
Test Method
The testing methods of the puncture resistance of packaging in China are mainly based on the relevant parts of the general rules for composite film bags for packaging (GB/T21302 -2007).
Principle of testing: the sample is fixed on the fixture, and the puncture needle installed on the moving Chuck punctures the sample. The force value changes are measured and recorded through the force value sensor and the displacement sensor located on the moving Chuck.
Test procedure
(1)5 samples with a diameter of 100mm were cut from the stretch film sample by the sampler.
(2) clamp the sample to the special jig for puncture test and fix the jig on the test equipment.
(3) setting test parameters such as test speed and sample thickness.
(4) click the start test option to start the test. The equipment automatically calculates and displays the final test results.
Puncture is used to indicate the ability of the stretch to resist puncture by a needle. It is expressed by the force value and the displacement when the membrane breaks during the puncture.
If the stretch film the poor puncture resistance, it is easy to sharpen objects punctured. Damage to the stretch film will result in loose separation of the product or cargo, which can not be protected.
