stretch film definition

stretch film definition

Early in blown film LLDPE stretch film as much, from the development to single-story, three; now the production of LLDPE cast stretch film based, the process shown below, this is because the production has a cast line thickness uniformity, transparency advantages, suitable for high power pre-stretch of the requirements. As the single-sided sticky tape can not do, applications are limited. Single, double cast in the material selection is not cast three wide, the high cost of formula, so the three-layer co-extruded structure or in a more ideal. High-quality stretch film should be transparent, vertical elongation, yield point, high, horizontal tear strength, puncture and good performance characteristics.
 
Stretch film production process conditions:
Casting method of production as long and narrow flow, flow speed, melt temperature range is generally controlled at 250 ℃ ~ 280 ℃, casting cooling roll temperature was controlled at 20 ℃ ~ 30 ℃, the winding tension is lower, usually in the 10kg or less, to facilitate the adhesive agent to move out, while reducing the finished membrane stress.
Viscosity control
Good adhesion to the goods outside of the packaging film layers stick together and bring the firm, sticky, there are two access methods: one is to add in the PIB polymer or the parent material; the other is the mixing VLDPE . PIB is translucent viscous liquid, add directly to the need for special equipment or modify the equipment, generally using PIB masterbatch. PIB is to move out of a process, generally three days, also affected by temperature, high temperature adhesive strength; low temperature is not sticky, sticky after stretching significantly reduced. Therefore finished film preferably stored at a certain temperature range (recommended storage temperature 15 ℃ ~ 25 ℃). Mixing VLDPE, sticky bit weak, but there are no special requirements for equipment, viscosity is relatively stable, without time control, but also affected by temperature, the temperature is higher than 30 ℃, relatively sticky, somewhat less than 15 ℃, the viscosity can be By adjusting the amount of LLDPE adhesive layer, to achieve the desired viscosity. Three-layer co-extruded multi-use of this approach.
Physical and mechanical properties of the control
High degree of transparency will help identify the goods; high longitudinal elongation beneficial pre-stretch, and saving material consumption; good puncture resistance and tear strength allows the membrane lateral tension in the high magnification face sharp corners or goods side is not broken; high yield point to packaged goods more tightening. Casting method of production of the film transparency, do not focus on here. With the material comonomer increased the number of C atoms, branched-chain length increases, lower crystallinity, the resulting copolymer "wound or kink" effect increases, so the elongation rate, puncture strength and tear strength are also improved. The MPE is Gao polymer stereoregularity, molecular weight distribution is very narrow, you can precisely control the physical properties of the polymer, so there are further performance improvement; and because MPE narrow molecular weight distribution, processing range is narrow, difficult to control processing conditions, usually Add 5% of LDPE, in order to reduce the melt viscosity, increase the flatness of the film. MPE's prices are high, in order to reduce costs, usually MPE and C4-LLDPE with use, but not all of the C4-LLDPE can be associated with, should have a choice. Machine with stretch film to use more C6, C8 material, easy processing, to meet a variety of packaging requirements. As the stretch ratio low hand packing, the use of C4 material. Material density also affect the membrane performance. As the density increases, the degree of orientation increased, good flatness, vertical elongation rate, yield strength, but the lateral tear strength, puncture strength and light transmission rate of decline, so integrated in all aspects of performance, often in non-stick Add the appropriate amount of medium density layer linear polyethylene (LMDPE). Add LMDPE non-sticky layer can also reduce the friction coefficient, to avoid the packed pallets and pallet adhesion. Chill roll temperature. Chill roll temperature, the yield strength increased, but the rest of performance degradation, so I generally cooling roll temperature was controlled at 20 ℃ ~ 30 ℃ appropriate. Cast film line tension effects and rolling flatness tightness, the use of PIB or parent material as the adhesive layer, but also affect the PIB's move to reduce the viscosity of the final film. Tension is generally not more than 10kg, too much stress remaining in the membrane volume, so that elongation performance, easily lead to broken membrane phenomenon. The application form stretch film stretch film applications is very broad, mainly used in conjunction with the tray, the whole set of fragmented commodity packaging, instead of small containers. Because it can reduce the volume of goods transport packaging costs more than 30%, which is widely used in metal, mineral, chemical, pharmaceutical, food, machinery and other products of the whole set of packaging; in the warehouse storage area, but also greater use of foreign three-dimensional packaging stretch film pallet storage to save space and area.
Edit this paragraph the use of stretch film form
Sealed packaging
This package is similar to shrink film packaging, the whole film around the pallet to pallet wrap, and two children to grasp both ends of the heat seal film together. This is the first use of stretch film form, and thus the development of more packaging
Full width packing
This package requires wide enough to cover the film tray, tray shape rules, so has its use for film thickness 17 ~ 35μm
Manual packaging
This package is the easiest stretch film packaging of a membrane mounted in a rack or by hand, by turning the tray around the tray or membrane switch. Mainly used in the wrapped tray damaged after the re-packaging, and general pallet packaging. This package is slow, for the film thickness of 15 ~ 20μm;
Winding stretch film packaging
This is one of the most common form of the most widely used mechanical packing, tray rotation or by the tray rotated around the film, the film can be fixed to the bracket up and down. The packaging capacity of large, about 15 to 18 per hour. Suitable thickness of about 15 ~ 25μm;
Horizontal packaging machine
Unlike other packaging materials by the membrane around the turn, for long the packaging of goods, such as carpet, sheet metal, fiber, profile, etc.;
Paper tube packaging
This is the latest use of stretch film, compared to the old-fashioned paper tube packaging stretch film packaging better. Suitable thickness of 30 ~ 120μm;
Small items of packaging
This is the latest packaging stretch film, not only can reduce material consumption, but also can reduce the pallet storage space, in a foreign country, this package was originally introduced in 1984, just one year later, there were many on the market such as packaging, This packaging has great potential. Suitable thickness of 15 ~ 30μm;
Pipe and cable packaging
This is a special field of application of stretch film in an example of packaging equipment installed in the last line, fully automatic stretch film instead of tape tied both materials, but also can play a protective role. Appropriate thickness of 15 ~ 30μm.
Stretch in the form of packaging tray body
Stretch film packaging are subject to stretching, stretch pallet packaging machinery in the form of direct tension and pre-stretch. Pre-stretch is divided into two, one is pre-stretch rollers, a tension is electric. Direct tension is between the tray and complete stretch film. This approach stretching ratio is low (about 15% to 20%), if the stretching ratio more than 55% to 60%, exceeding the yield point of the original film, film width reduction, and puncture resistance is also lost, the membrane is easy to break. And in 60% of the stretch rate, the tension is still very great, for light goods, is likely to bring the deformation. Pre-stretch is completed by the two rollers. The two pre-stretch roller roller gear unit is linked together, stretch ratio can vary according to the gear ratio, tension generated by the turntable, the tension is generated within a short distance, the friction between the roll and film big, so wide and indented film, film to maintain the original puncture performance down. No stretching occurs when the actual wound, reducing the sharp edge or corner as result of the fracture, which can stretch the pre-stretch ratio increased to 110%. Power pre-stretch stretch stretch mechanism and the same pre-roll, two rolls is different from the power driven rotating tray stretch completely unrelated. So adaptable, light, heavy, no rules are applicable to the goods, the packaging when the tension is low, so this method is 300% pre-stretch ratio, significantly reducing material cost savings. For film thickness 15 ~ 24μm.
Stretch film (LLDPE )features:
Units of: This is the largest stretch film packaging one of the characteristics. With superior film strength and retraction of the wound, the product tightly fixed to tied into a single unit, so that scattered small pieces into a whole, even under adverse conditions without any loose products and separation, degree and no sharp edge and sticky, so as to avoid injury. Primary protection: provide primary protection products, surface protection, the product formed around a very light, protective appearance, so as to achieve dust, oil, moisture-proof, waterproof, anti-theft purposes. Of particular importance is the stretch film packaging so that packaging materials even by force, to avoid uneven force caused by damage to the goods, which is the traditional packaging (bundling, packaging, packing tape, etc.) can not be done. Fixity compression: with stretch film (LLDPE)retraction after stretching force will wrap packaging products to form a compact, space-saving unit as a whole, the product of the tray tightly wrapped together, can effectively prevent the transport process of mutual dislocation and mobile products, while tensile strength can be adjusted so that the product close to hard to make soft products tightening, especially in the tobacco industry and textile industry has a unique packing effects. Cost savings of: the use of stretch film for packaging, can effectively reduce the cost, with original box packing stretch film is only about 15%, 35% of shrink film, carton of 50%. And can reduce labor intensity and improve the efficiency of packaging and packaging grades. To sum up, stretch film applications is very broad, but not yet involved in many domestic areas, has been involved in many areas has not widely used, with the expansion of application fields, stretch film will greatly increase the amount of , its market potential is immeasurable. So we need to promote the production of stretch film and application. PE stretch film and stretch film introduces PE stretch film (also known as Stretch) has a high tensile strength, tear strength, and good self-adhesive, so make wrapped objects into a whole, to prevent the collapse of the transport scattering time. The film has excellent transparency. Wrapped objects beautiful, and make objects waterproof, dustproof, anti-corruption. The film is widely used for pallet packing, such as electronics, building materials, chemicals, metal products, auto parts, wire and cable, daily necessities, food, paper and other industries tied wrapped packaging. Specifications: machine film width 500mm, manual film width 300mm, 350mm, 450mm, 500mm, thickness of 15um-50um. Cut a variety of specifications available online. Viscous sub-sided sticky double-sided adhesive, the product sub-hand stretch film and machine stretch film two series. Features: The product is anti-buffer strength, tear resistance to puncture with good performance, thin, good cost performance. Has a high tensile strength, tear strength, transparency and good retraction force, 400% pre-stretch ratio, can be assembled, waterproof, dustproof, anti-theft scattered and so on. Uses: used in wrapping pallets and other packaging wrap, widely used in foreign trade, bottle cans, paper, hardware, electrical appliances, plastics, chemicals, building materials, agricultural products, food and other industries. Stretch Film PE film products for industrial use fitted with high tensile strength, elongation, good self-adhesive, high transparency material point. For manual stretch film, stretch film machine can also be used, can be widely used in a variety of goods centralized packaging. PE stretch film mainly by the work of several different grades of polyethylene extrusion from allyl resin mixture, puncture resistant, super-strength high-performance, stacked on pallets of goods on the wrapped package, to make the packaging more secure clean, more super- Strong waterproof, has been widely used in foreign trade, paper, metal, plastic chemicals, building materials, food and pharmaceutical industries. PE stretch film: LLDPE stretch film, based on high quality LLDPE for the substrate, do not increase with the tackifier quality, through heating, extrusion, casting, and then cooled by the chilled roll formed, with high toughness, high elasticity, tear, high viscosity, the thickness of thin, cold, heat, pressure, dust, water, a single stick and double-sided adhesive, etc., can save the use of materials, labor-saving , save time, widely used in paper making, logistics, chemicals, plastic raw materials, building materials, food, glass and so on. PE Stretch Film Slitting: LLDPE is a high quality of the substrate, do not increase with the tackifier quality, through heating, extrusion, casting, and then by chilling the cooling roll made with high toughness, high elasticity , tear, high viscosity, the thickness of thin, cold, heat, pressure, dust, water, a single stick and double-sided adhesive, etc., can save the use of materials, labor-saving, save time, widely used in the paper, logistics, chemical, plastic raw materials, building materials, food, glass and so on. Stretch Film Stretch Film with film theory superior force and retraction of the wound, the product tightly fixed to tied into a single unit, so that scattered small pieces into a whole, even under adverse conditions without any loose products and separation , degrees and no sharp edges and sticky, so as to avoid injury.