Performance and application of the hottest BOPP sm

Performance and application of BOPP cigarette film

Abstract: This paper briefly describes the various properties of BOPP cigarette film, mainly including sliding performance, antistatic performance, stiffness, heat sealing performance, optical performance, and analyzes their application in the cigarette packaging process, providing a reference for the majority of peers to take out lighters and open valves to the maximum production and use BOPP cigarette film

key words: BOPP cigarette film polypropylene friction coefficient elastic modulus

BOPP cigarette film is also known as "biaxially stretched polypropylene cigarette film", which is called cigarette film for short. It is co extruded and stretched by a variety of polypropylene functional materials. This product has high transparency and luster, non-toxic material, stable molecular structure, and certain barrier function to odor and moisture, so it is an ideal material for cigarette packaging

in the early 1990s, China began to introduce and study the production technology of BOPP cigarette film. In the mid-1990s, a breakthrough was made through scientific and technological innovation, and BOPP cigarette film has become an emerging industry in China's flexible packaging industry. BOPP cigarette film has also been recognized as a high-tech product by the state

the production of BOPP smoke film has high technical content, which is a very complex work, in which the relevant mechanical, physical and chemical factors may affect and interfere with each other, and it is necessary to have a good balanced control over the properties of the film

1 ﹐ sliding performance and its application

friction coefficient is an index to measure the sliding characteristics of BOPP smoke film. For the operation of cigarette packaging on the machine, appropriate friction coefficient is very important

the friction coefficient of the outer surface of the film must be low, especially at high temperature. In the process of cigarette packaging, the outside of the film slides on the lower film channel, forming wheel groove, folding plate, soldering iron, guide rail and other metal parts. Because most of these metal parts operate under high temperature conditions above 50 ℃, the friction coefficient of the film will increase with the increase of temperature conditions, and the friction coefficient will rise faster after 30 ℃, so the thermal sliding performance can better reflect the actual working conditions of the packaging machine, Generally, it is ideal to control the thermal sliding friction coefficient at 50 ℃ between 0.30 and 0.42

the friction coefficient between the inner surface of the film and the cigarette packet box paper should be controlled to be high, that is, to create the differential sliding characteristics between the inner surface and the outer surface of the film, so as to facilitate the good positioning of the cigarette packet and the film in the forming wheel, improve the folding quality and obtain a compact packaging effect

since the slip enhancer of BOPP is usually added to the middle layer by migration, it takes a period of time to store before it can migrate to the surface of the film to play a role, that is, the film is relatively smooth after a period of time. Therefore, experienced manufacturers will purchase the film inventory in advance and reuse it after a period of time

2 ﹐ antistatic property and its application

in the process of cigarette packaging, film static electricity has an adverse effect on the cutting, conveying and folding process, which will cause the film to run on the machine. Antistatic property is one of the basic conditions for the smooth operation of the packaging machine

in the process of cigarette packaging, the static electricity of the film is divided into two parts, one is the static electricity of the film itself, and the other is the static electricity generated by friction in the process of cigarette packaging. The static electricity of the film itself is easy to control, but the static electricity generated in the cigarette packaging process is difficult to control, and it is more harmful to the machine operation failure. Manufacturers who have no experience in cigarette film production will only emphasize that the static electricity value of the film itself is small, and ignore the static electricity generated in the packaging process. As a result, the film detection performance is very good, but the machine operation packaging is always faulty

like the previous slip enhancers, antistatic agents are also added to the middle layer with mobility. Similarly, in order to obtain better antistatic effect, the film needs a certain storage period

on the cigarette factory packaging machine, static electricity can be transferred through rapid conduction of metal or static eliminator. In addition, the environment with high humidity is also conducive to the removal of static electricity on the film surface. In case of film with large static electricity or dry season (such as November), the cigarette factory can put the film into the packaging workshop in advance. It is ideal for the packaging workshop to adjust the humidity, or wet the workshop floor with water, or apply a wet towel on the end face of the film roll, which is an emergency solution, and it is more one of the laws that serve all kinds of civil needs

3 ﹐ stiffness and its application

stiffness is a quantitative index indicating the stiffness of cigarette film, which is proportional to the cubic equation of elastic modulus and thickness. The relationship between the three is as follows:

im - stiffness e - elastic modulus B - width H - film thickness

when the stiffness of cigarette film is high, it can obtain high folding quality in the packaging process, and overcome the adverse effects of static electricity on the cutting, transportation and folding process of cigarette film, It is conducive to reducing the operation failure of smoke film on the machine. In particular, some old-fashioned packaging machines must require smoke films with high stiffness to operate normally

in order to reduce costs, some cigarette factories strictly control the quantitative thickness of BOPP smoke film. The thinner the smoke film, the lower the stiffness. The stiffness will be reduced by about 300 units by about 1 um. Therefore, if the thickness is excessively thinned, the stiffness loss of the smoke film will be great, which will eventually have an adverse impact on the machine operation of the smoke film. Generally, it is ideal to control the thickness of the smoke film at 20-22um

4. Heat sealing performance and its application

1 use and characteristics heat sealing performance mainly includes heat sealing strength and heat sealing temperature range. Heat sealing strength reflects the thermal bonding fastness of smoke film, and heat sealing temperature range reflects the adaptability of smoke film to different temperatures during use

good heat sealing strength can ensure the shielding protection of cigarette packs against cigarette smell and prolong the storage life of cigarette packs. The smoke film with a wide range of heat sealing temperature can achieve a good heat sealing effect in a very short pause time. It is a prerequisite for improving the packaging speed and is suitable for high-speed packaging machines with automatic speed change. The output of some cigarette packaging machines is unstable, especially the poor temperature control system of some old cigarette machines, which leads to the frequent change and instability of heat sealing conditions. A wide range of heat sealing temperature can ensure the smooth operation of cigarette packaging

the smoke film with a narrow range of heat sealing temperature shows that the window for adjusting the heat sealing temperature is very narrow on the cigarette packaging machine. If the set heat sealing temperature is slightly higher, the hot mouth will wrinkle, and if the set heat sealing temperature is slightly lower, it will not seal tightly. Moreover, the heat sealing temperature setting between one roll and another roll is different, so it is difficult to control the heat sealing temperature

5. Optical properties and their applications

although the human eye is the best tool to evaluate the optical properties of thin films, it is not enough to control it only by vision, because lighting conditions, observer mood and quantitative control will all affect it. In order to obtain reliable and achievable quality assurance, objective and measurable parameters are needed to quantify the appearance. Gloss and haze are two important indicators for quantifying the optical properties of BOPP films

haze, also known as transparency, measures the percentage of transmitted light that deviates from the direction of incident light by more than a certain angle. Through the film observation, the narrow angle scattering is relatively clear, and the scattering angle will cause the contrast to be reduced and hazy. The lower haze can show the clear and bright trademark pattern of the cigarette bag

gloss is the visual impression obtained when evaluating the film surface. The more light directly reflected from the surface of the film, the higher the gloss. The light reflected by the high gloss surface is highly concentrated and can clearly reflect the image. The light reflected by the low gloss surface diffuses in all directions, and the imaging quality is reduced. The reflected objects are no longer bright but blurred. The high gloss will bring a bright visual effect to the cigarette bag

6. Conclusion

(1) for the operation of cigarette packaging on the machine, the friction coefficient of the outer surface of the cigarette film, especially under high temperature, must be low, and the friction coefficient of the inner surface of the cigarette film and the cigarette box paper should be controlled high

(2) the smooth operation of the packaging machine requires that the smoke film has anti-static characteristics. Static electricity can be transferred through the metal or static eliminator on the packaging machine. In addition, the environment with high humidity is also conducive to the removal of static electricity on the film surface

(3) higher smoke film stiffness can reduce the operation failure of the machine. The thicker the smoke film, the higher the stiffness

(4) the heat sealing performance mainly includes the heat sealing strength and the heat sealing temperature range. The heat sealing strength reflects the thermal bonding firmness of the film. Good thermal viscosity can ensure the smoke shielding protection of cigarette packets, and the heat sealing temperature range reflects the adaptability of the film to different temperatures during use

(5) gloss and haze are two important indicators for quantifying the optical properties of BOPP film. A lower haze can show the clear and bright trademark pattern of the cigarette bag, and a higher gloss will bring a bright visual effect to the cigarette bag

source: packaging magazine Author: Chen Guangzhong (Zhanjiang Packaging Materials Enterprise Co., Ltd.)