Tensile orientation principle of polymer molecular

Principle of polymer molecular chain stretching and orientation of POF heat shrinkable film

POF heat shrinkable film is designed based on the principle of polymer molecular chain stretching and orientation, and is formed by rapid cooling and shaping. Its physical principle is: when the polymer is in a high elastic state, it will be stretched and oriented, and then the polymer will be quenched to below the glass transition temperature, and the molecular orientation will be frozen. When the article is heated during the packaging process, due to the thermal movement of the molecule, the stress will relax, and the original state will be restored, resulting in shrinkage. At present, the common heat shrinkable films in the market include PE shrinkable film, PVC shrinkable film, PP heat shrinkable film, POF coextrusion shrinkable film, etc. the functions and installation methods will be described in detail above. In the large family of heat shrinkable packaging films, POF three-layer coextrusion heat shrinkable film (pof-c3) is a new generation product that has gradually risen and been accepted by people in recent years

1 High transparency and good gloss

2. It is flexible and easy to use

3. The shrinkage rate is large, and the highest shrinkage rate can reach 75%

4. Good sealing performance, high strength, suitable for manual, semi-automatic and high-speed automatic packaging

5. It has good cold resistance and can maintain flexibility at - 50 ℃ without embrittlement. It is suitable for the packaging to be stored and transported in a cold environment

6. Environmental friendly and non-toxic. The main raw materials of pof-c3 heat shrinkable packaging film include LLDPE (linear low density polyethylene), TPP (ternary copolymer polypropylene), PPC (binary copolymer polypropylene) and necessary functional additives, such as smoothing agent, anti everyone knows adhesion agent, antistatic agent, etc., which are non-toxic materials. Comply with FDA standards, can be packaged food

7. Damp proof and dust-proof

8. The packaging cost is low, which is superior to the packaging of cartons and other materials

the company has introduced production equipment and raw materials. At present, two production lines have been put into operation. However, the domestic application of pof-c3 series heat shrinkable packaging film is still in its infancy, with a narrow application range and an annual demand of about 25000-30000 tons. However, it has development potential in the fields of stationery, electrical appliances, medicine, food and so on. In addition to being directly used for packaging, POF heat shrinkable film can also be used for printing after corona treatment

processing technology of three-layer coextrusion heat shrinkable packaging film

preface

<3-layer coextrusion heat shrinkable packaging film is a new environmental friendly non-toxic heat shrinkable packaging material produced by coextrusion blow molding process with PE and PP as the main raw materials. Originated in Italy in the early 1990s, it has been widely used in developed countries such as Europe and the United States. It is mainly used in the outer packaging of beverages, convenience foods, daily chemical products, audio-visual products, books and periodicals, medicine, electronic components and other daily necessities, especially suitable for the packaging and length measurement of supermarket goods. The method is to confirm the wear loss according to the change of the normal dimension of the friction surface before and after the experiment. The shelf storage. The main features of this product are:

1. It has high transparency and good gloss, which can clearly show the appearance of the product, improve the sense of perception, and reflect high-grade

2 ﹐ large shrinkage rate, up to 75%, good flexibility, can package goods of any shape, and the shrinkage force of the three-layer coextrusion film treated by special process is controllable, meeting the requirements of different commodity packaging for shrinkage force

3. Good sealing performance and high strength, suitable for manual, semi-automatic and high-speed automatic packaging

4. It has good cold resistance, and can maintain flexibility at - 50 ℃ without embrittlement. It is suitable for the packaging to be stored and transported in a cold environment

5 ﹐ environmental friendly and non-toxic, in line with FDA and USDA standards, it can pack food

since 5 ~ 6 years ago, China has successively introduced equipment and raw materials to produce three-layer coextrusion heat shrinkable film. At present, more than 10 production lines have been put into production, showing a good momentum of development. This paper introduces the raw materials, processing technology and product properties of three-layer coextrusion heat shrinkable packaging film, and compares its properties with PVC heat shrinkable packaging film, so as to discuss the development prospect of three-layer coextrusion heat shrinkable packaging film

main raw materials of two-layer and three-layer coextrusion heat shrinkable packaging film

. The main raw materials of three-layer coextrusion heat shrinkable packaging film include LLDPE (linear low density polyethylene), TPP (ternary copolymer polypropylene), PPC (binary copolymer polypropylene) and necessary functional additives such as smoothing agent, anti adhesion agent, antistatic agent, etc. These raw materials are environment-friendly and non-toxic materials, which will not produce toxic gases and odors during processing and product application. The hygienic performance of the products meets the standards of FDA and USDA, and can be used for packaging food

production process of three-layer and three-layer coextrusion heat shrinkable packaging film

. The three-layer coextrusion heat shrinkable packaging film is processed by coextrusion blow molding process with linear low density polyethylene (LLDPE) and copolymerized polypropylene (TPP, PPC) as the main raw materials, adding necessary additives. Its process is different from the traditional blow molding process. Due to the poor tensile properties of PP melt, the traditional blow molding process cannot be used, but the double film bubble process is used, It is also called prandi process in the world. It is to melt and extrude raw materials through different extruders, form the initial film through a specially designed coextrusion die, then quench it, and then heat it for secondary expansion and drawing to produce products. The process flow is shown in Figure 1:

main performance of four and three-layer coextrusion heat shrinkable packaging film

1 product specification three-layer coextrusion heat shrinkable film can produce various specifications according to its purpose, and the general thickness range is 12 μ m～30 μ m. The common thickness is 12 μ m、15 μ m、19 μ m、25 μ M, etc. the width specification depends on the volume of the package

2. Physical properties the physical properties of three-layer coextrusion heat shrinkable packaging film are shown in Table 1

3 ﹐ cold resistant three-layer coextrusion heat shrinkable packaging film remains soft at - 50 ℃ without embrittlement, which is suitable for the storage and transportation of the packaged goods in cold environment

4 ﹐ hygienic performance the raw materials used in the three-layer coextrusion heat shrinkable packaging film are environmental friendly and non-toxic materials. The processing and use process is hygienic and non-toxic, in line with the national FDA and USDA standards, and can be used in food packaging

performance comparison between five and three-layer coextrusion heat shrinkable packaging film and PVC heat shrinkable packaging film

three-layer coextrusion heat shrinkable packaging film has obvious advantages over PVC heat shrinkable packaging film, so it is gradually replacing PVC heat shrinkable film and is a new favorite in heat shrinkable packaging materials. See Table 2 for the performance comparison between the two

application prospect of six and three-layer coextrusion heat shrinkable packaging film

. The three-layer coextrusion series heat shrinkable packaging film is widely used, has a broad market, and has the advantages of environmental protection and non-toxic. Therefore, it has been widely valued by the developed countries in the world, and has basically replaced PVC heat shrinkable packaging film as the mainstream product in heat shrinkable packaging materials. The production of this series of products in China began in the mid-1990s. At present, there are more than ten production lines in China, all of which are imported equipment, with a total production capacity of about 20000 tons. Due to the certain gap between China's packaging technology and the international developed countries, the three-layer coextrusion series heat shrinkable packaging film for degradable plastic products in Jilin market is still in the preliminary stage of domestic application, and the application scope is still relatively narrow, which is limited to a few fields such as beverages, audio-visual products, convenience food and a small number of daily chemical products, with an annual demand of about 25000 ~ 30000 tons. PVC heat shrinkable film also occupies a considerable heat shrinkable packaging market, with great development potential. With the integration of China into the international market after joining the WTO, the gradual improvement of packaging requirements for a large number of export commodities, and the rapid development of domestic supermarkets, the application of three-layer coextrusion heat shrinkable packaging film will grow rapidly. It can be predicted that the market prospect of three-layer coextrusion series heat shrinkable film is very broad

source: Shenzhen Hengxin packaging material factory