Cellphone:+8615221892684

Email: sasha@duxiapackage.com

Cellphone:+8615221892684

Email:sasha@duxiapackage.com

Cellphone:+8615221892684

Email:sasha@duxiapackage.com

Discuss the development trend of degradable packaging

  The flexible packaging film raw materials we currently use are basically non-degradable materials. Although many countries and companies are currently working on the development of degradable materials, there are currently no alternatives that can be mass-produced for degradable materials that can be used in flexible packaging. As the country pays more and more attention to environmental protection, many provinces and cities have successively issued regulations that restrict plastics and even “ban plastics” in certain areas. Therefore, for composite flexible packaging companies, a correct understanding of degradable materials is a prerequisite for making good use of degradable materials and realizing green and sustainable packaging.
A. Definition and classification of degradable plastics.
    The degradation of plastics refers to the process in which the structure of plastics undergoes significant changes and performance loss due to environmental conditions (temperature, humidity, moisture, oxygen, etc.). The degradation process will be affected by many environmental factors. According to its degradation mechanism, degradable plastics can be divided into photodegradable plastics, biodegradable plastics, photo-biodegradable plastics and chemically degradable plastics. Biodegradable plastics can be divided into completely biodegradable plastics and incomplete biodestructive plastics according to their degradation methods.
      1. Light-degradable plastic Light-degradable plastic means that the plastic material undergoes a cracking and decomposition reaction under sunlight, causing the material to lose its mechanical strength within a period of time after sunlight exposure, turning into a powder, and some can be further decomposed by microorganisms. Natural ecological cycle. In other words, after the molecular chain of photodegradable plastic is destroyed by photochemical method, the plastic loses its own strength and becomes brittle, and then becomes powder through natural corrosion, enters the soil, and re-enters the biological cycle under the action of microorganisms.
     2. Biodegradation of biodegradable plastics is generally considered to be defined as: Biodegradation refers to the process of chemical conversion of compounds through the action of biological enzymes or chemical degradation with microorganisms. In this process, it is also possible Accompanied by reactions such as photodegradation, hydrolysis, and oxidative degradation. The mechanism of biodegradable plastics is: plastics in which high-molecular materials are decomposed into carbon dioxide, methane, water, mineralized inorganic salts and new substances by bacteria or hydrolase. In other words, biodegradable plastic refers to a type of plastic that is degraded by the action of microorganisms in nature, such as bacteria, mold (fungus) and algae. The ideal biodegradable plastic is a kind of polymer material with excellent performance, can be completely decomposed by environmental microorganisms after being discarded, and finally inorganicized to become a component of the carbon cycle in nature. That is, the molecules that decompose into the next level can be further decomposed or absorbed by natural bacteria and other substances. The principles of biodegradation are divided into two categories: The first category is biophysical degradation. When microorganisms attack and erode high polymer materials, the polymer components will be hydrolyzed, ionized or protonated and split into oligomer fragments due to the thinning of organisms. The molecular structure of the polymer remains unchanged, which is a degradation process caused by the biophysical action of the polymer. The second category is biochemical degradation. Due to the direct action of microorganisms or enzymes, the polymer is decomposed or oxidized and degraded into small molecules until it is finally decomposed into carbon dioxide and water. This degradation method is a biochemical degradation method.
     3. Biodegradable degradable plastics. Biodegradable degradable plastics, also known as collapsible plastics, are composite systems of biodegradable polymers and general plastics, such as the combination of starch and polyolefin, and they are combined in a certain form. , The degradation in the natural environment is not complete, and it is likely to cause secondary pollution.
     4. Completely biodegradable plastics According to their sources, completely biodegradable plastics mainly include high molecular polymers and their derivatives, microbial synthetic high molecular polymers and chemically synthesized high molecular polymers. At present, the most researched and applied composite flexible packaging is starch plastics.
     5. Natural biodegradable plastics Natural biodegradable plastics refer to natural polymer plastics, biodegradable materials prepared from natural polymer materials such as starch, cellulose, chitin, and protein. The sources of such substances are rich and diverse, can be completely biodegradable, and the products are safe and non-toxic. Based on different degradation methods and the requirements of different regions, the degradable materials currently recognized by our clients need to be completely degraded, and whether it is landfill or compost degradation, it requires the degradation of existing plastic materials into carbon dioxide, water, and minerals. Chemical inorganic salts and other substances can be easily absorbed by nature or recycled by nature again.

     B. Features of degradable plastics
     1. The material is natural and non-toxic.
     2. The use of any waste treatment methods (such as composting, burying, etc.) has a minimal impact on the environment.
     3. It can replace traditional plastics based on petroleum, and has the material properties of similar traditional plastic products, so there is relatively little need to change the way of use.
     4. After being abandoned, after being composted or buried, it can be cracked into next-level molecules within a short period of time, and can be harmlessly absorbed by nature or turned into mineralized inorganic salts.
      C. Common misunderstandings about degradable plastics
      1. Equal bio-based plastics as biodegradable plastics. According to relevant definitions, bio-based plastics refer to plastics produced under the action of microorganisms based on natural substances such as starch. The biomass used in the synthesis of bio-based plastics can be derived from corn, sugar cane or cellulose. Biodegradable plastics refer to under natural conditions (such as soil, sand, sea water, etc.), or under specific conditions (such as composting conditions, anaerobic digestion conditions or aqueous culture fluids, etc.), by microorganisms (such as bacteria, molds, etc.) , Fungi, algae, etc.) cause degradation, and eventually completely degrade the plastic that becomes carbon dioxide, water, methane, mineralized inorganic salts and new substances. Bio-based plastics are defined and classified based on the source of material components; while degradable plastics are classified from the perspective of material end of life. In other words, 100% of bio-based plastics may not be biodegradable, while some traditional petroleum-based plastics can be biodegradable, such as butylene terephthalate (PBAT) and polycaprolactone (PCL) .
    2. Degradable is considered to be biodegradable. The degradation of plastics refers to the process of significant changes in structure and loss of performance under the influence of environmental conditions (temperature, humidity, moisture, oxygen, etc.). Specifically, it can be divided into mechanical degradation, biodegradability, photodegradation, thermal oxygen degradation and photooxidation degradation. Whether a certain plastic will be completely biodegraded is affected by many factors, including crystallinity, additives, microorganisms, temperature, environmental pH, and length of time. When conditions are not available, many degradable plastics not only cannot be completely biodegraded, but may also have negative effects on the environment and human health. For example, under the action of additives, some oxygen-degradable plastics only break down and degrade into plastic particles invisible to the naked eye.
   3. Regarding the biodegradability under industrial composting conditions as biodegradable in the natural environment, that is, compostable plastics as equivalent to biodegradable plastics. The two cannot be completely equal to each other. Compostable plastics belong to a category of biodegradable plastics. Biodegradable plastics also include plastics that are biodegraded in an anaerobic manner. Compostable plastics refer to plastics that can be converted into carbon dioxide, water and mineralized inorganic salts and new substances of the elements in a certain period of time through the action of microorganisms under composting conditions, and the final formed compost heavy metal content and toxicity test , Residual debris, etc. should comply with relevant standards. Compostable plastics can be further divided into industrial compost and garden compost. Compostable plastics currently on the market are basically biodegradable plastics under industrial composting conditions. Because compostable plastics are biodegradable under conditions, if you randomly discard compostable plastics in the natural environment (such as sea water and soil), these plastics will degrade very slowly in the natural environment and cannot be completely degraded in a short time. The adverse effects of carbon dioxide and water on the environment are not substantially different from traditional plastics. In addition, studies have pointed out that if biodegradable plastic is mixed into other recyclable plastics, it will reduce the characteristics and performance of recycled materials. For example, the starch in polylactic acid may cause pores and spots in the film made of recycled plastic.
    D. The current situation and pain points of the application of degradable plastics in flexible packaging. At present, some flexible packaging companies are trying to use degradable plastics to produce packaging. The main problems currently presented are:
    1. The variety is small and the output is small, which cannot meet the requirements of mass production. If the base material is degradable, of course the fabric needs a completely degradable material. Otherwise, the base material can be completely degraded. We can never hold petroleum-based PET, NY , BOPP is used as a fabric to match the PLA material to compound, so the meaning of doing so is almost zero, and it may be worse, even the possibility of recycling will be obliterated. However, currently there are very few fabrics available for composite flexible packaging, the supply chain is very scarce, and it is very difficult to find, and production capacity is very scarce. Therefore, it is a difficult problem to find a degradable fabric that can be suitable for gravure printing on soft packs.
    2. Functional development of bottom-layer degradable materials For composite flexible packaging, the degradable materials that can be used for the bottom layer are particularly important, because many packaging functions are realized by the bottom-layer material. However, there are very few degradable materials that can be applied to the bottom layer of composite flexible packaging in China. And even for some base material films that can be found, whether their key physical properties, such as stretchability, puncture resistance, transparency, heat-seal strength, etc., can match the existing packaging needs, is still a relatively hazy unknown. There are also related hygiene indicators and barrier properties, and it is necessary to study whether it can meet the packaging requirements.
     3. Whether the auxiliary materials can be degraded. When the fabric and base material can be found, we also need to consider whether the auxiliary materials, that is, ink, glue, etc., can match the substrate and whether they can be completely degraded. There are many disputes on this point. Some people think that the ink itself is particles, and the amount is very small, and the proportion of glue is also very small, which can be ignored. However, according to the above definition of fully degradable, strictly speaking, as long as the material is not completely decomposed to be easily absorbed by nature and can be recycled in nature, it is not considered to be truly completely degraded.
    4. At present, most producers in the production process still have a lot of problems to be solved in the use of degradable materials. Whether in the printing process, or in the process of compounding or bag making, finished product storage, we need to find out how different this type of degradable packaging is from the existing petroleum-based composite packaging, or what needs our attention . At present, there is no relatively complete control system or standard applicable to popularization. V. Conclusion At present, for degradable packaging, customers are more concerned about whether it can meet the performance requirements of packaging; for flexible packaging manufacturers, they must consider which areas can be used and how much can be used, because degradable materials are It can be degraded conditionally in the short term. Currently, degradable materials have not yet formed a mature supply chain. Therefore, packaging in the next few years may be recyclable packaging and degradable packaging go hand in hand.

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