What are the parameters of the stretch film?

Table of Contents

Stretch film is the most widely used in our life and industrial production. It has good retraction memory and self-adhesion can make the goods tightly wrapped into a whole, to prevent flash falling and dust pollution during transportation. Production of stretch film to comply with the international quality test standards, many users in the choice of stretch film do not know what the test standards for stretch film, today Sinyar Packing film for you to introduce.

stretch film difference

Plastic film is a highly stretchable film that is wrapped around certain items, and is often used in the packaging industry. The main function of the membrane is to improve load stability for transportation, storage and pollution protection. The stretch film is usually made of PE (Lldpe, VLDPE, Plastomers) but PVC is also used. The key properties of stretch films are elastic recovery and fracture strength, and adhesion, puncture resistance and optical properties are also very important.

BB/T0024-2004″stretch film for transport packaging” industry standard was implemented on June 1, 2004, the standard uses the American standard ASTM D4649″tensile winding film selection and use guide”(the latest standard ASTM D 4649-03(09)). BB/T0024-2004″ stretch film for transport packaging” standard applies to polyolefin plastic as the main raw material for the production of non-direct contact food, and transport packaging for the stretch winding film. The technical requirements of the standard for stretch films are divided into three parts: dimensions and specifications, appearance and physical and mechanical properties:

Dimensions, specifications and appearance

Size and specification are the basic specifications for customers when ordering. This standard mainly refers to ASTM D 4649 standard of America and provides the items of width deviation, thickness deviation, coiling length deviation, coiling inner diameter deviation and film quality deviation which are suitable for our country’s actual situation. These indicators are in line with or above the ASTM standard.

Appearance requirement is an important part of product standards in our country. In this standard, the quality of broken end, air bubble, perforation, rupture, block, fisheye and flatness of membrane is required. The evaluation method is based on the GB/T10457-1989 analysis method of appearance items and has been modified.

stretch film

Physical and mechanical properties

BB/T0024-2004《 tensile winding film for transport packaging 》 mainly stipulates the technical indexes of tensile breaking force, elongation at break, viscosity, permanent deformation, elastic recovery, tensile force retention, F force value, puncture resistance, mass deviation per unit area, transmittance, haze and water vapor transmission.

| 1. Tensile strength and elongation at break

Tensile strength and elongation at break, also known as tensile properties, tensile properties is a very important indicator of the winding film, the test method used GBT 13022-1991″plastic film tensile properties test method” test method standard, then from the standard type I, II, III, IV four samples of the final selection of type IV (strip) test, the width of 15 mm, tensile testing machine chuck distance 50 mm, standard distance 50 mm, the test speed was 250mm/min ± 25mm/min. This is not only in line with the majority of domestic businesses GE but also to achieve sample-making convenience. In addition, the elongated specimen can be used without an extensometer, which avoids the defect that the stretch film is so thin that the extensometer has a great influence on the friction of the stretch film and is easy to break. The XLW series intelligent electronic tension tester produced by lab think Language is recommended.

| 2. Water vapor transmission

To indicate whether the wrapped film can protect the product from moisture or hygroscopicity in sea transportation or a high humidity environment. The measurement of water vapor transmission is of great importance. The method uses the GBT 1037-1988 plastic film and the sheet water vapor transmission test method standard to check the water vapor transmission. Testing can use LABTHINK language production weighing principle TSY-T series moisture permeability tester.

sinyar packing film certificate

| 3. Other physical indicators

The standards of viscosity, tensile retention, permanent deformation, elastic recovery, and puncture resistance refer to the ASTM organization of the United States that developed about tensile stretch film test method standard. The following is a brief introduction to viscosity, tension retention, permanent deformation, elastic recovery, and puncture resistance test items. The testing indexes can be tested by XLW series intelligent electronic tensile testing machine or bld-200 s electronic stripping testing machine.

3.1 adhesion: the adhesion between the two layers of the stretch film under tension or non-tension.

3.2 elastic recovery: the filament is maintained for a certain time after being stretched in a certain proportion, and the ratio of the recovered size to the original size after being released is expressed as a percentage.

3.3 permanent deformation: the ratio of the length of the filament to the original length, expressed as a percentage after the filament is stretched.

F force value: the maximum tensile force of the stretch film at a predetermined elongation.

3.4 tension maintenance: the ratio of the tension force to the F force for a certain period of time after the stretch film is stretched in a certain proportion is maintained as the tension force, expressed as a percentage.

3.5 puncture resistance: used to indicate the ability of a stretch film to resist needle puncture. It is expressed by the force of rupture of the membrane during puncture and the displacement of membrane during puncture.

3.6 light transmittance and fog

Stretch film needs to have good transparency in use. Test method for transmittance and fogging of transparent plastics by GB/T 2410-1980. At present, the majority of domestic production enterprises are also using this standard to assess. Note: Light Transmittance and fog test are limited to transparent and colorless products with film thickness below 0.030 mm.

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