PE heat shrinkable film knowledge

Classification of LDPE heat shrinkable film

LDPE heat shrinkable films are divided into two categories: cross-linked and non-cross-linked. Generally, manufacturers use raw materials with MFR of 0.3-1.5g/10min when producing non-cross-linked LDPE heat-shrinkable films. The lower the melt index, the more uniform the shrinkage performance. And the greater the tensile strength, the more suitable for packaging. Some manufacturers use radiation treatment in production to improve various properties of heat shrinkable films.
PE heat shrinkable film can meet the packaging requirements of most commodities, and is the most widely used heat shrinkable film. The MI used of LDPE particles is 0.3-1.5g/min. Heavy packaging shrink film or shrink film with high strength requirements, use LDPE particles with a lower limit of MI, LDPE molding temperature is 130-180 ℃, pre-cool with cold air below 25 ℃, and then inflate close to the frost line, once Longitudinal and transverse stretching, the total stretching ratio can reach 15-35, and then the film is quenched at 10-25 ° C to wind or shrink the film. The general shrinkage rate is 30%-50%.
Features are:
1. The uncrosslinked LDPE shrink film is relatively soft, has good impact resistance, and has a certain tear strength;
2. Good low temperature resistance;
3. Easy to process and form, easy to heat seal bag;
4. No shrinkage occurs during storage. Shrink wrapping for glass, ceramics, food, building materials, chemicals, pallets, etc. The thickness of light packaging is 0.02-0.06mm, and the thickness of heavy and large pallet packaging is 0.075-0.25mm.

Properties of LDPE shrink film:
1. Thin film thickness is 0.02-0.05mm, medium type is 0.05-0.10mm, and thick type is 0.10-0.15mm;
2. The tensile strength is 28-38MPa for thin type, 20-30MPa for medium type, and 20-28MPa for thick type;
3. Shrinkage rate of thin type is 55%-65%, medium type is 45%-60%, thick type is 30%-50%; shrinkage temperature oil bath is 110-120℃, hot air is 170-180℃;
4. Shrinkage time is 5-10s for thin type and 20-30s for thick type.
The minimum thickness of shrink film for packaging less than 400kg is 120μm, 800kg needs 150μm thickness, and 1200kg goods need LDPE shrink film with 200μm thickness.