Application of the hottest high performance resin

2022-10-22
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Application of high-performance resin in packaging

after noting these three points, in recent years, with the improvement and improvement of production technology of high-performance resin, it has been applied in flexible packaging film, making it possible to improve its machinability, sealing, barrier, transparency, gloss, strength and toughness, printability, recycling and reusability. In particular, the following three special resins are very attractive in the field of flexible packaging films: cyclic olefin copolymers (COCs), liquid crystalline polymers (LCPs) and styrene butadiene copolymers (SBCs). Now it is introduced as follows:

cyclic alkene copolymers (COCs)

COCs are copolymers formed by the polymerization of n-alkene and dicyclic alkene, which have excellent properties of flexible packaging. The single-layer hybrid film composed of COCs and common lignin plastics, including lignin/pvc ethylene (PE), can give full play to its best performance. Its advantage is to strengthen the toughness and sealing, with high water resistance and film transparency

if COCs are mixed with low density polyethylene (LDPE), it will hardly affect other composite films. Domestic enterprises, scientific research institutions and other enterprises and institutions have gradually begun to enter the characteristics of independent research and development of products in this field, which improves the strength and toughness of packaging films on the whole. Mixing with PE can further enhance the strength and toughness of the film with increasing the amount of COCs. Food packaging can change the thickness of packaging materials through the mixing of PE and COCs_ And reduce the production cost of packaging film materials

LDPE combined with COCs can improve the strength, toughness and tightness of standing bags. It can replace composite and coextrusion packaging bags with high production costs

cocs can reduce the haze value (fog vapor) and turbidity value of PE and reduce the friction coefficient, so it can greatly improve the processing efficiency of materials and the speed of packaging process. After coextrusion of COCs and PE, there is no need to bond the intermediate layer, but coextrusion with polypropylene (PP), polyvinyl chloride (PVC), polyester (PET) and ethylene vinyl alcohol copolymer (EVOH) and other materials requires bonding the intermediate layer

in flexible packaging with multi-layer structure, COCs are generally used as the central layer because of their good water resistance. The water resistance of COCs is twice that of high-density polyethylene (HDPE) and seven times that of polypropylene (PP)

the high water barrier of COCs protects EVOH, which will reduce the oxygen barrier once moisture is absorbed, that is, the co extrusion processing of EVOH and COCs can effectively avoid the above problems

liquid crystalline polymers (LCPs)

in the past two years, LCPs have been introduced as "super barrier" materials. However, the high price and the difficulty of processing into packaging materials have always been the difficulties and suspense of using this resin as packaging materials

the key to using LCPs to make flexible packaging is that it needs to be processed like pet low-cost plastic, which can be coextruded into thin and uniform thin layers through multi axial extension, so as to form film materials for packaging

now, the new LCPs can be coextruded by using standard devices and general resin raw materials, thus solving the above problems. The advantages of the new LCPs are: high barrier to oxygen, water vapor, carbonic acid (carbon dioxide), aromatic taste and aroma

the product "Vectran" of Ticona company is a pinhole free barrier film product developed and produced by the company. This LCPs film can generally be used for multilayer composite films. Only one tenth of the thickness of EVOH has the same degree of barrier. Therefore, the consumption of materials can be reduced and the production cost can be reduced. The melting point of LCPs is 220 ~ 350 ℃. Due to its good chemical stability, it can be coextruded with LDPE, PE, extended PP, nylon and many other packaging materials

The high barrier and heat resistance of LCPs can reduce the production cost of packaging film and improve the packaging efficiency. For example, cooking bags that can withstand high temperature and high pressure treatment can be co extruded with LCPs to save the amount of aluminum foil. Even if the relative humidity reaches 100%, the oxygen resistance of this cooking bag can reach more than ten times that of EVOH when it is steamed and sterilized under high temperature and high pressure. Since the LCPs film will not absorb water during high temperature and high pressure treatment, when the high temperature and high pressure treatment ends and the pressure drops to normal pressure, the structure of the composite layer can be guaranteed to be intact and will not be damaged

at present, the manufacturing companies of LCPs include superex polymer and Ticona

styrene butadiene copolymer (SBCs)

the commercial production of styrene butadiene copolymer resin has been more than 30 years. Through the research and improvement of transparency and impact resistance in recent years, it has achieved great growth and development in the flexible packaging market. Films based on SBCs can be used as an effective substitute for low-density films with good cost efficiency. The film based on SBCs can be heat sealed into packaging bags at 110 ~ 177 ℃ using the commonly used heat sealing method

SBCs are very suitable as packaging materials because of their low relative barrier property. For example, in order to maintain the freshness of packaged fruits and vegetables, respiratory activities must also be carried out, and there are certain requirements for the balance conditions of oxygen, carbon dioxide and water vapor. SBCs have gas permeability to emit carbon dioxide and water vapor and introduce oxygen. At the same time, it can also prolong the shelf life of packaged fruits and vegetables by inhibiting their respiration

and for different fruits and vegetables, the necessity of oxygen is also different, so when used as a packaging film, it can be made into packaging materials that can meet the use requirements by using additives and coextrusion processing with polymers of other packaging films according to the official of Oak Ridge National Laboratory

now, two companies in the world, including chevron Philips chemical and Kraton polymer, produce SBCs

it must be pointed out that when choosing such high-performance resins, the price of materials is a very important issue. Therefore, when studying the use of such resin materials as flexible packaging film raw materials, we must consider the balance between film performance and price

secondly, we must also recognize the economic benefits and benefits of the advantages of high-speed sealing, no leakage and no failure sealing brought by the selection of high-performance resin materials

when selecting resin for film, we must first meet the requirements of products in terms of capital investment. If the use of these high-performance resins can help to meet the goals and requirements of the market and investors, then the value of investment and utilization of new materials can be generated

source: Chinese magazine

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