Composite bag heat sealing effect is good, depends on the 6 o 'clock

Composite bags if heat sealing is not good, will affect the appearance and seal performance, absolutely cannot careless in this respect. The stand or fall of compound bag heat sealing largely related to the following 6 points. 1, heat sealing temperature, heat sealing temperature of the composite membrane of choice and the performance of the composite base material, thickness, bag making machine model, there is a close relationship between speed, air pressure, etc, which directly affect the heat sealing strength of high and low. Composite bags sealing temperature is made of heat sealing materials of sticky flow temperature or melting temperature, heat sealing temperature of high temperature cannot exceed the decomposition temperature of the heat sealing materials. Sticky flow between temperature and decomposition temperature the temperature of the heat sealing temperature range for the heat sealing materials, it is a key factor to affect the quality and control the heat sealing. Heat sealing temperature range is wide, the better the performance of heat sealing, quality control more easily and more stable. At the same time composite film heat sealing temperature not higher than the printing substrate heat setting temperature. Otherwise it will cause heat sealing parts of the contract, corrugate, reduces the heat sealing strength and shock resistance of the bag. Printing substrate temperature resistance good, such as the BOPET, BOPA etc. , improve the heat sealing temperature can increase the production rate; Printing substrate temperature resistance is poor, such as BOPP, using low heat sealing temperature as far as possible, and by increasing the pressure, reduce the production speed or choose low temperature heat sealing materials to ensure that the heat seal strength. 2, heat sealing pressure hot air pressure is provided by the pressure spring bag making machine. The size of the heat sealing pressure and the performance of the composite film width, thickness, heat sealing and so on. Polarity, heat sealing materials have higher activation temperature on the viscosity of the decline in influence is bigger, so the required heat sealing pressure is small, prevent heat sealing parts out of the molten material, heat sealing effect. Nonpolar and PE, PP material, the activation performance is very small, the required pressure is higher, is good for heat sealing strength, interface sealing. Heat sealing pressure shall be as the composite film thickness increases. Jorge sealing pressure is not enough, two film heat-seal hard, difficult to exhaust all sandwiched between weld bubbles; Heat sealing pressure is too high, will squeeze out the molten material, welding edge damage, cause increased. To calculate the heat sealing pressure, want to consider the width of the required heat sealing rods and the actual surface area. The width of the heat sealing bar is wider, the required pressure. Heat sealing bar width is too wide, easy to make the heat sealing part entrained air bubbles, it is difficult to heat sealing strong, generally can use hollow out heat sealing bar, strengthen heat sealing fastness in the last email. The same width of heat sealing bar, if the surface of the moment, the actual contact area is greatly reduced, pressure per unit area increases accordingly, it is beneficial for the packing bag of heat sealing width is larger. 3, heat sealing speed heat sealing reflect the efficiency of bag making machine, is also the important factors influencing the heat seal strength and appearance. The faster the heat sealing and heat sealing temperature to increase, to ensure that the intensity of heat sealing and heat sealing state to achieve best value; Under the same heat sealing temperature and pressure, heat sealing the slower speed, heat sealing material fusion will more fully and more strong, but it can't cause increased phenomenon. Domestic production of bag making machine, heat sealing time length is mainly determined by the speed of bag making machine. Increase the heat sealing time, must reduce the bag making speed, reduce the production efficiency. If the independent variable frequency motor control heat sealing bar lifting and conveying, independent adjust time of heat sealing, without changing the bag making speed, will greatly facilitate the operation of the bag making machine and quality control. 4, cooling cooling process is under constant pressure, with low temperature to finalize the design just melt sealing weld, eliminate stress concentration, reduce the shrinkage of weld, improve the appearance of the bag flatness, improve the process of heat sealing strength. Bag making machine of the cooling water is generally tap water or about 20 ℃ circulating water. High water temperature, cooling rod pressure is not enough, not enough cooling water circulation, circulation and so on can lead to poor cooling, heat sealing strength decreased. 5, the most number of heat sealing bag making machine of the longitudinal and transverse heat sealing adopts hot plate welding, longitudinal heat sealing number depends on the effective heat sealing bar length and the ratio of the bag length, lateral heat sealing number is determined by the number of sets of the machine heat sealing device. Good heat sealing general requirements heat sealing number in more than 2 times. Most lateral heat sealing device is taken as the three groups. In order to satisfy the requirement of the broad-brimmed heat sealing, tend to increase the lateral heat sealing device, increase the number of heat sealing, in order to reduce the heat sealing temperature, reduce the necking phenomenon. For longer specifications of the bag, can use many times feeding technology, make each feed length to bag long half or one third, so as to increase the number of heat sealing, improve heat sealing effect, but will reduce the production efficiency, so some bag making machine to increase the length of the longitudinal heat sealing bar, to increase the number of heat sealing, ensure the quality of heat sealing. Heat sealing bar 6, heat sealing rods clearance gap refers to the heat sealing bar when in contact with the base plate, a predetermined distance hot air pressure to the pressure on the surface of the heat sealing. In the same film thickness, heat sealing speed, heat sealing bar, small gap heat sealing time is relatively small, the composite bag heat sealing strength will reduce. General heat sealing gap set at 1. 0 to 1. 5 mm, with thin film thickness, transmission performance, bag making speed and so on.