Shampoo is a common daily chemical product, which is mainly used for the daily care of head skin and hair. The commonly used packaging forms include bottle and pouch. The pouch shampoo includes large volume and small volume. Small volume (e.g. 5ml) shampoo pouches are mostly for one use. This kind of pouch shampoo brings convenience to consumers; a common problem is that the pouch is not easy to tear open, which may diminish the convenience. In order to improve the tear performance of the pouch, a certain shape of tear notch is usually preset on the shampoo package. However, due to the large tear resistance of the packaging material itself or the weak interlayer composite, the tear notch is not easy to tear, or the outer layer and the inner layer is stretched and separated, which brings inconvenience. In addition, when using the shampoo, it is inevitable to splash water on the surface of the packaging pouch, thus increases the difficulty of tearing the packaging open. Therefore, it is an effective measure to improve the tear ability of shampoo packaging pouch by testing and controlling the tear performance of packaging materials.

2. Test standard

The test methods for tear performance of soft plastic packaging include right angle tear method, Trouser tear method and Elmendorf method. In this paper, the test samples are torn at the tear notch, according to the shape of the tear notch and the angle of force applied when being torn, the Trouser tear method is used to test the samples. The test standard is ISO 6383-1 Plastics — Film and sheeting — Determination of tear resistance — Part 1: Trouser tear method.

3. Test sample

In this test, a brand of shampoo packaging aluminum composite film was used as the test sample.

4. Test instrument

The test equipment used in this paper is XLW (PC) Auto tensile tester, which is independently developed and produced by Jinan Labthink Instruments Co., Ltd.

4.1 Test principle

The trouser tear test method refers to that the shape of the test sample is similar to “trouser”. Clamp two legs of the test sample in the upper and lower grips of the instrument. When the upper grip moves upward, one leg of the test sample will be pulled to tear the test sample along the long axis. The load cell and the displacement sensor record the load and displacement change during the tearing process and form a test curve, take the mean of the recorded force values as the tear force of the sample, and calculate the tear strength of the sample.

5. Test process

1)      Specimen: cut 5 specimens from the test sample in the direction of processing and against the process direction respectively. The size of the specimen is 150 × 50 mm, the length of the slit in the center of the specimen shall be 75.0 mm. The test specimen shall be cut so that the edges are smooth and free from notches.

2)      Conditioning: place the test specimen in a condition of 23℃. 50%RH for 4 hours.

3)      Measure the thickness: measure three spots on the specimen in equal interval and take the average value of the three measurements.

4)      Parameters settings: set specimen name, thickness, test speed, number of specimens and other parameters.

5)      Start the test: clamp the two legs of the specimen on the upper and lower grips of the instrument, click “start” to start the test.

6)      End test: when the test is completed, the instrument displays the tear force and tear strength. Repeat the above steps to test the rest of the specimens.

6. Test result

The longitudinal tear strength of the sample tested in this test is 11.465 kN / m, and the transverse tear strength is 8.027 kN / m.

7. Conclusion

The easiness of tearing open a shampoo pouch is an important factor of the convenient use. In this paper, XLW (PC) auto tensile tester is used to test the trouser tear strength of a brand of shampoo’s aluminum coated composite film packaging sample. The test process is simple and the instrument is easy to operate. In addition to tear force, the oxygen resistance, sealing performance, composite fastness, heat sealing strength and other properties of the packaging bag should also be tested to prevent the oxidation, deterioration, leakage and bag breaking of shampoo.

Jinan Labthink Instruments Co., Ltd, is dedicated to providing customers with packaging testing solutions and helping the manufacturers to reach their goals of quality and safety assurance through improvement of packaging testing techniques and development of high-end packaging testing instruments. The newly introduced C series barrier testing systems adopting self-sensing technology revolutionarily improved the testing accuracy, efficiency and automation, realized the paradigm shift of packaging barrier testing instruments. For more information please visit www.labthink.com