Bi-directional stretch film production process

Flat film method step by step bi-directional stretching process as follows: raw materials → extrusion → casting → longitudinal stretching → cutting edge → corona treatment → winding → large film rolls → aging → slitting → finished product.

Thick film for stretching should be amorphous, process to achieve this purpose, the measures taken for crystalline polymers is in the thick film extrusion immediately after the implementation of the rapid cooling, in which the thickness of the thick film is generally 12 to 16 times the stretching film. After the longitudinal and transverse orientation of the film should be shaped at high temperatures to reduce internal stresses and obtain a stable size, and then cooled, cut edges, rolled. If you need to print and then increase the EDM treatment and other processes.

The production process of biaxially orientated films is divided into two parts: preparation of thick film and biaxially orientated stretching, which includes extrusion of the sheet base, casting, longitudinal stretching, transverse stretching, trimming, surface treatment, winding, waste recycling, ageing and slitting.

Process parameters for different bi-oriented films:.

Polypropylene: film thickness 10~60μm, extrusion temperature 250~270°C, casting temperature 30~40°C, longitudinal stretching temperature 125~145°C, stretch ratio 4.5~6.0, transverse stretching temperature 160~170°C, stretch ratio 9.0~10.0, heat treatment temperature 170~180°C.

Polystyrene: film thickness 100~500μm, extrusion temperature 230~240℃, casting temperature 80~110℃, longitudinal stretching temperature 110~125℃, stretch ratio 2.5~3.5, transverse stretching temperature 110~125℃, stretch ratio 2.5~3.5, heat treatment temperature 100~110℃.

Polyester (polyethylene terephthalate): film thickness 6~40μm, extrusion temperature 285~295℃, casting temperature 30~40℃, longitudinal stretching temperature 115~125℃, stretch ratio 3.5~5.0, transverse stretching temperature 60~70℃, stretch ratio 3.3~3.5, heat treatment temperature 240~250℃.

Polyamide: film thickness 40~100μm, extrusion temperature 250~270℃, casting temperature 30~40℃, longitudinal stretching temperature 55~60℃, stretch ratio 2.8~3.2, transverse stretching temperature 60~70℃, stretch ratio 2.8~3.2, heat treatment temperature 210~220℃.

After production, bi-oriented film must be aged, i.e. stored in the air at a certain temperature for a certain period of time. The role of aging is to release tensile stress and make the additives that work on the surface of the film migrate to the surface of the film. Generally, the film is aged at room temperature for 2 to 3 days and then slit.

Nanjing Suminoe Precision Machinery Co., Ltd. is a collection of scientific research, production, sales in one of the high-tech enterprises, and has always adhered to the integrity, equality, the interests of the customer first business philosophy, in order to better improve the quality of the equipment, into a more professional and standardised production track. We set up a plastic sheet, sheet, casting, bi-oriented, non-woven nonwoven meltblown cloth, film composite, renewable granulation and environmental protection recycling system and coating machine manufacturing system and other seven categories of equipment, independent research and development technology centre and production departments, to provide a professional full set of technical solutions to meet the special needs of each customer. Among them, the bi-directional stretch film manufacturing system has: BOPP bi-directional stretch film manufacturing system, PVC bi-directional stretch shrink film production line, PET bi-directional synchronous stretch film production line, BOPA bi-directional stretch film production line, BOPLA bi-directional stretch film production line and so on.