Research progress, application status and Prospect

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Research progress, application status and prospects of paper-based packaging materials

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core tip: the application history of packaging materials can be traced back to the early days of human civilization, and it is a crucial part of the packaging industry. With the increasing environmental pollution and the gradual increase of people's awareness of environmental protection, the application history of packaging materials can be traced back to the early stage of human civilization, and it is a vital part of the packaging industry. With the increasing environmental pollution and the gradual enhancement of people's awareness of environmental protection, low-carbon, environmental protection and energy conservation have become the focus of global attention. The green research, development and application of packaging materials have also become the focus of attention. In recent years, relevant research and industrial application have developed rapidly. On January 19, 2020, the national development and Reform Commission and the Ministry of ecological environment issued the "opinions on further strengthening plastic pollution control" (hereinafter referred to as the "opinions"), which was called the new version of the "plastic restriction order" by the industry. From the perspective of the new opportunities and challenges faced by the packaging industry and the paper industry under the new "plastic restriction order", this paper systematically discusses the research progress and application status of paper-based packaging materials, especially the hot research and application materials in paper-based packaging materials in recent years - paper-based composite packaging materials and pulp molding packaging materials, It provides research directions and ideas for expanding the application fields of paper-based packaging materials and developing innovative technologies and industrialization of functional paper-based packaging materials

1. Overview of paper-based packaging materials

paper-based packaging materials refer to a class of natural plant fiber-based materials used for packaging purposes. Paper based materials are the most familiar, earliest used and most widely used green environmental protection materials. At present, paper-based materials widely used in the packaging field include traditional packaging paper and paperboard materials, new functional paper-based packaging materials, paper-based composite packaging materials and pulp molding packaging materials. In recent years, with the rapid development of e-commerce, express delivery, takeout and other emerging industries and the construction and encouragement of rural logistics by the state, the pollution caused by plastic packaging products has attracted more and more attention. The development trends at home and abroad have shown the importance and urgency of "plastic limitation", which has brought new opportunities for the development of paper-based packaging materials industry. But at the same time, due to the limitations of the inherent properties of natural plant fiber materials, paper-based packaging materials have encountered new challenges in the process of replacing plastic packaging materials

in the traditional pulp and paper industry, paper-based materials are endowed with the properties of resisting liquid penetration and diffusion through the treatment of internal or surface sizing. With the gradual expansion of the application of paper-based materials in the packaging industry, the traditional sizing technology has long been unable to meet the performance requirements of paper-based materials in some fields. According to the requirements of packaged products for packaging materials, such as the cushioning performance, surface performance, barrier performance, etc. of paper-based packaging materials, it has become the trend of functional research of paper-based packaging materials to study different treatment processes and technologies to improve and enrich the performance of paper-based materials to meet the needs of different fields

2. Research and application progress of paper-based composite packaging materials

paper-based composite packaging materials refer to multifunctional composite packaging materials formed by taking packaging paper or paperboard as the substrate and combining other materials with paper substrate through certain processing technology. Paper based composite packaging materials are based on the properties of various materials, learn from each other, and make full use of the excellent barrier, heat preservation, antibacterial and other properties of metal materials, polymer materials and other substrates, as well as the ecological and environmental protection properties of natural plant fibers. They generally include paper base, functional layer and thermal seal layer. According to the types and categories of composite process and auxiliary materials, paper-based composite packaging materials can be divided into paper/plastic/aluminum composite packaging materials and paper/polymer composite packaging materials

paper/plastic/aluminum composite packaging materials rose around 1980. With the introduction of packaging equipment, there is still support for short-term mineral prices, and their applications in China have developed rapidly. However, due to the wide variety of raw and auxiliary materials used in paper/plastic/aluminum composite packaging materials, their recovery is difficult and costly. Most of the waste paper/plastic/aluminum composite packaging materials are treated as worthless waste, resulting in waste of resources and environmental pollution. Based on the pressure of environmental protection and resource conservation, people began to reconsider the paper/plastic/aluminum composite packaging technology from the source of materials to the impact of the whole process of processing and molding and waste on the environment

paper/polymer composite packaging material is a kind of composite material that combines paper-based materials with different properties and polymer materials through a certain process. The types of polymers used in paper/polymer composite packaging materials can be divided into two categories according to environmental protection performance: non biodegradable plastics and biodegradable polymers (paper-based biopolymer composite packaging materials). The research of paper-based biopolymer composite packaging materials focuses on the performance modification and type expansion of biopolymers, the performance improvement and optimization of packaging materials based on the needs of packaging contents, the research of coating and composite technology, the interfacial compatibility between paper-based materials and biopolymer coatings, etc. Polylactic acid (PLA) is the most promising new aliphatic polyester biopolymer. However, the current polylactic acid paper-based composites have shortcomings in durability and barrier performance, and the cost is higher than that of traditional plastic film coated paper-based composites. When used as packaging materials, they will still encounter practical problems in one way or another. There are still many problems to be overcome in order to realize the real industrial application

3. New paper-based packaging materials: pulp molding products

the pulp molding industry originated in Europe in the 1930s. Molding technology was first applied to the plastic industry as a molding processing technology. Through the combination with papermaking technology, a three-dimensional papermaking technology using natural plant fiber materials pulp molding was derived. Pulp molded products have the characteristics of non-standard, small batch and small quantity, which brings great challenges to the R & D and use efficiency of pulp molded products production equipment. During the development of paper molded products with a relative humidity of 20% RH, the focus of relevant research work has also shifted from how to reduce production costs and expand the scope of product application to deeper optimization of the performance of pulp fiber raw materials, research and development of additives, measurement of physical and chemical characteristic parameters of pulp and its molded products, research and development of special molding equipment Structural design of pulp molded products and optimization of production and processing parameters

pulp molded packaging products have always had problems such as insufficient apparent smoothness and easy chip falling. The research on the surface properties of pulp molded products at home and abroad is still in the initial stage, and the research on improving the surface properties of products from raw materials, additives, surface treatment technology and other aspects has just begun. Due to the late development of the pulp molding industry, there are few and relatively simple studies on its special barrier properties. However, since the main raw materials of pulp molding products are pulp fibers with various properties, which belong to natural fiber cellulose based materials, relevant studies can be based on the effects of natural fiber cellulose based materials on the barrier mechanism, barrier process Progress in barrier additives

pulp molded products have been developed in China for more than 30 years, especially with the help of the "plastic restriction" law, they have been more and more widely recognized and used in the field of environmental protection industrial products packaging and disposable environmental protection tableware. However, some common technical problems of pulp molded products need to be solved, such as mold making, surface modification process of pulp molded products, research on slurry preparation, high energy consumption in the production process And the lack of unified industry standards, which requires the upstream and downstream industrial chains of the pulp molding industry to research and solve key problems. With the wide application of pulp molded products in the field of high value-added packaging, how to integrate intelligent packaging technology into the production process of pulp molded packaging materials, and how to integrate nano materials or high-strength fiber materials. The water pollution prevention action plan recently issued by the Chinese government also confirms that this material is applied to pulp fiber raw materials to produce pulp molded packaging materials with special properties, It is an important research direction and development trend of the industry in the future

4. Outlook

paper based packaging materials are an important material for the cross accommodation of the two pillar industries of the national economy - the paper industry and the packaging industry. In recent years, the types of finished products of paper-based packaging materials have become more and more diverse based on the expansion of application fields. For example, in the field of takeout delivery, the environmental pressure caused by disposable plastic tableware and packaging is increasing day by day. In order to support the construction of green supply chain in takeout industry, the "Castle Peak project special fund" jointly initiated by China Environmental Protection Foundation and meituan takeout has specially set up the "recommended list of paper takeout packaging and innovative product incubation project" to help promote the use of paper packaging products in takeout field. With the continuous extension of the application scenarios of paper-based packaging materials, the pressure of environmental protection and resource-saving economy, and people's higher and higher requirements for packaging materials, paper-based packaging materials have posed more and more challenges. In general, driven by the new version of the "plastic limit order" in early 2020, the paper-based packaging industry has not only ushered in new development opportunities, but also faced new challenges. Paper based packaging materials should strengthen innovation, develop mature substitutes that are equivalent to or close to the widely used non degradable plastic products in terms of performance and cost, and launch functional products that meet market demand

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