Flexible packaging film bag heat sealing material choice

Flexible packaging film bag heat sealing, is a key process in the plastic processing, heat sealing quality is directly related to the protection of by packaging effect. A packaging material, no matter how good the material once the heat sealing quality no, everything is empty. Here is mainly to discuss heat sealing characteristics of flexible packaging materials and the influence factors of heat sealing effect. ( A) Heat sealing strength heat sealing strength refers to the same or different plastic materials on the second floor under a certain melting temperature after certain pressure, heat together after to peel strength. According to the relevant standards, heat sealing is the temperature at 130 ℃ ~ 140 ℃, under the pressure of 1 KGF/cm2, in 2 ~ 3 seconds after the determination of the intensity of the heat sealing time. Many factors influencing the heat sealing strength, mainly has: ( 1) The performance of the resin; ( 2) The amount of additive ingredients and additives in the resin. ( 3) Processing and forming conditions, especially the extrusion coating process, the oxidation degree of the surface; ( 4) Thin film composite, the properties of heat sealing performance of the composite resin phase other materials, heat sealing strength and heat sealing temperature is different; ( 5) Composite operation, the degree of surface treatment, such as: the size of the corona treatment, etc. Polyethylene heat sealing strength related to the thickness of the polyethylene, as the heat sealing resin, such as the increase of the thickness of the PE, heat sealing strength increase, for example: when the LDPE heat sealing layer thickness of 20 microns, the peel strength, i. e. , heat sealing strength of 1. 0 KGF / 15 mm wide and 30 mu of 1 m thick. 40 mu 5 KGF / 15 mm, to 2 m thick. 5 KGF / 15 mm wide and 60 microns thick, peel strength can be up to 4. 2 KGF / 15 mm wide. This is why the high-temperature cooking bags of photosensitive material PE or PP film should be in 60 ~ 70 microns thickness. Heat sealing in the performance of the resin with heat sealing strength also has a close relationship, with a certain thickness of the composite membrane, in 2 KGF/cm2 pressure and 0. 5 seconds under the condition of heat sealing, under 150 ℃ heat sealing has the highest heat sealing strength, MI = 3. 7克/ 10分钟,d = 0。 923 g/cm3, heat sealing strength of 1. 25 KGF / 15 mm wide; MI = 3。 0g/10min，d=0. 921 g/cm3, heat sealing strength of 1. 4 KGF / 15 mm wide; MI =7. 0克/ 10分钟,d = 0。 917 g/cm3 heat sealing strength of 1. 75 KGF / 15 mm wide; MI = 9。 5g/10min，d=0. 917 g/cm3, heat sealing strength of 1. 9 KGF / 15 mm wide. That it increases with the increase of heat sealing strength with MI. ( 2) Low-temperature heat sealing is a low-temperature heat sealing heat sealing the measure of how easy it is to represent the heat sealing temperature and heat sealing strength of comprehensive factors. For LDPE resin, low temperature heat sealing have close relationship with MI and density. High MI and low density of LDPE, excellent low temperature heat sealing. For ethylene copolymer and ethylene polymerization monomer copolymerization monomer content and performance has a great influence on its low temperature heat sealing. For example: EVA, with the increase of the content of VA softening temperature drops, good low temperature heat sealing, the increase of the density of EVA, optimal improve low-temperature heat sealing. ( 3) Inclusion heat sealing property which refers to the heat sealing layer surface is stained with dust, greasy, sundry goods or packaging contents, still have a kind of good heat sealing strength performance, with the inclusion of heat sealing resin have all kinds of resin bonding and LLDPE. Various heat sealing: (with resin A) LDPE: this is the most commonly used heat sealing with resin, can use extrusion blow moulding or extrusion salivate method into thin film with other thin-film composite film again after use, can also be used in other films, aluminum foil, paper extrusion coating or composite membrane, but also with other resin squeeze into a composite membrane, its melting point between 105 ℃ ~ 120 ℃, heat sealing, good transparency, non-toxic. ( 2) MDPE and HDPE: melting point between 120 ℃ ~ 135 ℃, also have good heat sealing, transparency than LDPE, high crystallinity than LDPE, film strength is larger than LDPE, heat sealing temperature is higher than LDPE, generally speaking, the best PE heat sealing temperature in 150 ℃ ~ 160 ℃, then has the highest heat sealing strength. ( 3) PE copolymer: PE with other alpha carbon olefins, such as: octene copolymer, pentene etc, metallocene ( MPE) , LLDPE, etc. , and with acrylate and ethylene with ethylene vinyl acetate copolymer with maleic anhydride, vinyl, etc, the common characteristics of the resin is good low-temperature heat sealing, high heat sealing strength and good thermal bonding.