Characteristics of heat shrinkage of film
DATE：2019/9/18 8:59:23 / READ： / SOURCE：This station
The heat shrinkage rate of the film has the following characteristics:
1) Different types of plastic heat shrinkable films have different ranges of heat shrinkage. For the same kind of plastics, the relative molecular mass distribution of the resin is wide, and the longitudinal and transverse heat shrinkage ratios tend to balance; the density increases, the heat shrinkage initiation temperature increases; the melting point temperature increases, and the heat shrinkage rate decreases.
2) lowering the stretching temperature of the film, which is beneficial to lowering the initial temperature of the film heat shrinkage or making the film have a higher heat shrinkage rate at the same temperature;
3) the thickness of the heat shrinkable film is increased, and the heat shrinkage rate is lowered;
4) The heat shrinkage rate increases as the heating temperature during packaging operations increases;
5) The longitudinal and transverse stretching ratio of the film is larger than that of the film, and the heat shrinkage rate is increased; the film inflation ratio is increased, and the longitudinal and transverse heat shrinkage rates tend to be balanced.
In fact, when the heat shrinkable film is used, it is not necessary to reach its maximum shrinkage rate. Because, when the heat shrinkable film is used, the actual heat shrinkage rate is often determined by the size of the packaged article. For the heat shrinkable film of the printed image, a balanced longitudinal and transverse heat shrinkage rate is required; for a soft package, an excessive heat shrinkage rate causes the object to be deformed; for a cylindrical hard object, a higher transverse heat shrinkage is required. Rate to make the film close to the object. Therefore, the heat shrinkable film can have different heat shrinkage rates according to user requirements:
1 equalization of longitudinal and transverse heat shrinkage;
2 The longitudinal heat shrinkage rate is large, and the lateral heat shrinkage rate is small;
3) The longitudinal heat shrinkage rate is small, and the lateral heat shrinkage rate is large.
By changing the longitudinal and transverse stretching ratio of the film, it is the most common process for adjusting the longitudinal and transverse heat shrinkage of the film. For example, increasing the transverse stretch ratio (blowing ratio) of the film and lowering the longitudinal stretch ratio of the film can increase the transverse heat shrinkage rate and decrease the longitudinal heat shrinkage rate. In terms of production technology, it is required to have a longitudinal heat shrinkage rate close to 70% or a transverse heat shrinkage rate of less than 15% or a longitudinal heat shrinkage rate of less than 10%.
1) Different types of plastic heat shrinkable films have different ranges of heat shrinkage. For the same kind of plastics, the relative molecular mass distribution of the resin is wide, and the longitudinal and transverse heat shrinkage ratios tend to balance; the density increases, the heat shrinkage initiation temperature increases; the melting point temperature increases, and the heat shrinkage rate decreases.
2) lowering the stretching temperature of the film, which is beneficial to lowering the initial temperature of the film heat shrinkage or making the film have a higher heat shrinkage rate at the same temperature;
3) the thickness of the heat shrinkable film is increased, and the heat shrinkage rate is lowered;
4) The heat shrinkage rate increases as the heating temperature during packaging operations increases;
5) The longitudinal and transverse stretching ratio of the film is larger than that of the film, and the heat shrinkage rate is increased; the film inflation ratio is increased, and the longitudinal and transverse heat shrinkage rates tend to be balanced.
In fact, when the heat shrinkable film is used, it is not necessary to reach its maximum shrinkage rate. Because, when the heat shrinkable film is used, the actual heat shrinkage rate is often determined by the size of the packaged article. For the heat shrinkable film of the printed image, a balanced longitudinal and transverse heat shrinkage rate is required; for a soft package, an excessive heat shrinkage rate causes the object to be deformed; for a cylindrical hard object, a higher transverse heat shrinkage is required. Rate to make the film close to the object. Therefore, the heat shrinkable film can have different heat shrinkage rates according to user requirements:
1 equalization of longitudinal and transverse heat shrinkage;
2 The longitudinal heat shrinkage rate is large, and the lateral heat shrinkage rate is small;
3) The longitudinal heat shrinkage rate is small, and the lateral heat shrinkage rate is large.
By changing the longitudinal and transverse stretching ratio of the film, it is the most common process for adjusting the longitudinal and transverse heat shrinkage of the film. For example, increasing the transverse stretch ratio (blowing ratio) of the film and lowering the longitudinal stretch ratio of the film can increase the transverse heat shrinkage rate and decrease the longitudinal heat shrinkage rate. In terms of production technology, it is required to have a longitudinal heat shrinkage rate close to 70% or a transverse heat shrinkage rate of less than 15% or a longitudinal heat shrinkage rate of less than 10%.
Author：admin