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How to develop high-performance polyolefin products in China during the "14th Five-Year Plan"? What are the trends in technological development?
Release time:
2021-01-14
High-performance polyolefins are one of the key development focuses of advanced synthetic resins. In recent years, there has been rapid development in areas such as catalyst technology (e.g., metallocene catalysts), polymerization processes, and polymer processing technologies. New catalyst design and regulation methods (such as metal-metal synergistic effects, ligand secondary coordination effects, ligand-substrate effects, redox regulation, etc.) and new heterogeneous polymerization methods (such as self-stabilizing precipitation polymerization) have become effective ways for the efficient preparation of high-performance polyolefins.
High-performance polyolefins are one of the key development focuses of advanced synthetic resins. In recent years, there has been rapid development in catalyst technology (such as metallocene catalysts), polymerization processes, and polymer processing technologies. New catalyst design and control methods (such as metal-metal synergistic effects, ligand secondary coordination effects, ligand-substrate effects, redox control, etc.) and new heterogeneous polymerization methods (such as self-stabilizing precipitation polymerization) have become effective ways for the efficient preparation of high-performance polyolefins.
The variety of polyolefin grades continues to enrich, and the quality continues to improve, with products such as high melt strength polypropylene, high-density polyethylene pipe materials, transparent impact-resistant polypropylene, and capacitor film materials achieving application breakthroughs. Optical grade, film grade, electronic grade, and high-performance synthetic resins for additive manufacturing are developing rapidly and are being applied in various fields.
There is a serious lack of good products, with a heavy reliance on imports. How can the contradictions in the product structure of polyolefins be resolved during the "14th Five-Year Plan"?
The "13th Five-Year National Strategic Emerging Industry Development Plan" requires the development and expansion of strategic emerging industries such as the new generation of information technology and new materials. High-performance synthetic resins, as basic materials for advanced manufacturing categories, have also been included in the development plan. Breaking through the technical bottlenecks of high-performance synthetic resins, upgrading the existing material system, and meeting the needs of major projects and good manufacturing.
Green and environmentally friendly new synthetic resin products can meet the needs of high-quality life, such as safe and non-toxic toys and daily necessities, high barrier food packaging materials, etc. To meet the requirements for comfortable travel, high-performance synthetic resins are used to prepare low volatile organic compound (VOC) automotive interior materials, which have flame retardant, vibration reduction, and noise reduction effects, as well as new structural and decorative parts for high-speed trains.
Good grades of polyolefins (such as metallocene polyethylene, metallocene polypropylene, high carbon olefin copolymer polyethylene, etc.) and special polyolefins (such as ethylene-vinyl acetate copolymer (EVA) resin, ethylene-vinyl alcohol copolymer (EVOH) resin, polybutene-1, etc.) have a consumption of 1.138×10^7 t/a in China, but the self-sufficiency rate is less than 40%. Good synthetic resins such as polyvinyl butyral (PVB) film for laminated glass, electronic grade epoxy resin, and polyvinylidene fluoride (PVDF) membrane for power batteries are basically reliant on imports.
01
What are the development trends of high-performance polyolefin materials technology?
(1) Develop diversified raw material technology
The key to preparing high-performance polyolefins using diversified raw materials lies in optimizing feed control and ensuring raw material quality, flexibly using various raw materials for production through process optimization.
(2) Enhance catalyst technology
Research on polyolefin catalysts has shifted towards improving the comprehensive performance of products, with the main goal of enhancing the catalyst's control over polymer properties.
Metallocene catalysts have achieved fine-tuning of polymer chain length, branching degree, and stereoregularity. Compared to traditional Ziegler/Natta catalysts, polyolefin products made with metallocene catalysts have better regularity, controllability, and product performance.
In 2017, domestically developed carrier-type metallocene polypropylene catalysts were first put into use in a batch liquid-phase bulk polypropylene unit (8×10^4 t/a), filling a domestic technological gap.
Metallocene catalysts, with their high activity, single active center, and strong copolymerization ability, will continue to develop, allowing for more precise control of polymer molecular configurations and customized production to meet end-use products. The focus of related technology research is to further improve the morphology of metallocene polyolefins, widen their relative molecular weight distribution range, reduce the amount of expensive co-catalyst methylaluminoxane (MAO), and further lower the cost of metallocene catalysts.
In addition, the development of catalytic systems such as palladium diamine, salicylaldehyde imine nickel, and phosphonic acid palladium catalysts has achieved copolymerization reactions of polar monomers with olefins, significantly improving the surface properties, adhesion, flexibility, solvent resistance, rheology, and compatibility with other polymers and polymer material additives, which is also one of the future development trends.
(3) Coexistence of multiple polymerization processes
The number of polypropylene polymerization processes exceeds 20, especially gas-phase processes represented by Unipol, Novolen, and Innovene, which have developed rapidly in the past decade; multi-zone circulating reactor technology is also on the rise. The polymerization process of polyolefin elastomers (POE) is mainly based on the Insite solution polymerization process developed by Dow Chemical and the Exxpol high-pressure polymerization technology developed by ExxonMobil. In recent years, new chain transfer polymerization technology has been successfully developed based on Insite catalyst technology, resulting in high-performance olefin block copolymers.
(4) Equipment tends to be large-scale
The scale of single units for polypropylene projects under construction in China is concentrated at 300,000 to 450,000 tons/year, and significant progress has been made in the research and development of large-scale polyolefin production equipment. Domestic large extrusion granulation units can achieve 300,000 to 350,000 tons/year.
(5) Emergence of good grade products
The technology of polyolefin products aims to improve the comprehensive performance of products, focusing on developing new varieties, increasing product added value, and expanding product application fields.
In terms of polyethylene, heat-resistant polyethylene (PE-RT) developed from improved copolymer monomers has been used for building heating. By optimizing the polyethylene bimodal polymerization process, large-diameter polyethylene pipes with better low melt flow and crack resistance have been developed for oil fields and logistics transportation, as well as new products of metallocene polyethylene and ultra-high molecular weight polyethylene (UHMWPE) products that can be used for lithium battery membranes.
New products and new grades, including polypropylene materials for medical devices/medical protective products, antibacterial polypropylene materials, low extractable propylene-butylene copolymer polypropylene, and low VOC polypropylene materials, are also continuously emerging.
(6) Emphasis on the recycling and utilization of waste plastics
In the natural environment, plastic products are difficult to decompose naturally after use, and the recycling and utilization of plastic products have become a focus of global attention.
The main technologies for recycling and utilizing waste plastics include direct regeneration, modified regeneration, and chemical recycling. The chemical recycling method alters the bonding state of plastic macromolecules through methods such as thermal cracking, catalytic cracking, and thermal cracking-catalytic modification, resulting in the decomposition into various low molecular compounds or oligomers; it can be used to produce fuel oil, fuel gas, and chemical raw materials, becoming a promising recycling method.
02
Analysis and Response to Key Technologies of High-Performance Polyolefin Products
In the future, China's synthetic resin industry needs to continuously enhance technology, highlight good chemical and functional development directions, and further expand market scale.
The development of high-performance synthetic resins mainly has the following approaches: introducing good product production equipment and good brand production technology from abroad, learning-absorbing-innovating; utilizing existing equipment and technology for good product development, optimizing the product system; independently developing core key technologies such as catalysts, polymerization processes, and processing technologies, and producing good products with independent intellectual property rights.
(1) New Polyolefin Catalyst Preparation Technology
Metallocene catalysts are an important breakthrough for the domestic development of metallocene polyolefin products and achieving the localization of good products. Through breakthroughs in catalysts and key supporting process technologies, promote the further scaling up of products such as hexene-1/ octene-1 co-polymerized polyethylene and metallocene polyethylene, which already have a certain industrialization foundation, to improve self-sufficiency and achieve industrial-scale production of metallocene polyolefins.
To achieve the functionalization of polyolefins and improve surface performance, adhesion, flexibility, and compatibility with other materials, new catalytic systems such as palladium diimine, nickel salicylaldehyde imine, and palladium phosphonic acid are also key research directions.
(2) Solution Polymerization Process Technology
The solution polymerization process is widely applicable and can produce various products in the polyolefin sector, including high-density polyethylene, linear low-density polyethylene, polymer polyols (POP), POE, and α-olefins. Utilizing high-activity metallocene catalysts can prevent the elution of catalysts after polymerization, thus reducing energy consumption in the process.
Since the reaction needs to be carried out at high temperatures, the research focus is on developing catalysts that are heat-resistant, highly active, and have high co-polymerization capabilities, as well as studying the polymerization kinetics, mixing, and heat transfer enhancement mechanisms related to these catalysts.
(3) High Performance and Functional Modification of Synthetic Resins
Strengthening research on chemical modification, structural modification, and blending modification technologies to improve the mechanical properties, environmental resistance, and processing performance of materials, launching specialized products with multiple grades, and promoting the high performance of general synthetic resins. Strengthening the functional development of materials to give synthetic resin materials certain special properties, meeting the needs of special occasions such as ultraviolet absorption and photochromism.
(4) Advanced Processing Technology
To achieve multifunctionalization and composite of high-performance synthetic resins, it is necessary to deepen the research on the relationship between polymer processing technology and product performance, optimize processing technologies such as blending, filling, and enhancing modification of high-performance synthetic resins; develop advanced molding processes for resin-based composite materials and related supporting equipment, promote the large-scale application of resin transfer molding processes, as well as bi-axial stretching, extrusion casting, and multi-layer co-extrusion film molding processes, achieving high efficiency, energy saving, and integration of the entire process.
Response One: Utilize existing equipment and technology to develop good products and achieve large-scale applications.
In the field of high-performance polyolefin materials, accelerate the development of catalysts, processes, and processing technologies in key product areas such as high-pressure polyethylene and solution polymerization polyethylene, and quickly achieve the preparation of metallocene catalysts, large-scale production of trimethyl aluminum, and construction of ten-thousand-ton MAO production facilities. Under the existing equipment and technology conditions, implement technological breakthroughs to develop good brands and produce highly polymerized olefins.
In other high-performance synthetic resins, closely track international developments and new changes in industrial development, aiming at productization, differentiation, and specialization development goals, and large-scale application of independently developed core key technologies such as catalysts, polymerization, and processing; produce high-performance products with independent intellectual property rights, such as electronic-grade epoxy resins and polyvinylidene fluoride, gradually achieving large-scale domestic application.
Response Two: Strengthen basic research and talent cultivation to ensure technological innovation.
Reasonably strengthen investment in basic research and applied basic research, guided by achieving high performance and functionalization of synthetic resin materials, accelerate technological breakthroughs in new generation polyolefin catalysts, precise control of polymerization reactions, in-situ alloying and nanocompositing of synthetic resins. In-depth study of the impact of key molding technology indicators on material performance and microstructure, promoting the practical application of high-performance synthetic resin technologies with new structures and compositions.
Focus on talent cultivation in the field of high-performance synthetic materials, based on the advantages of higher education institutions in specialized disciplines and talent cultivation, strengthen enterprise practical education, form a mechanism for joint talent cultivation among higher education institutions, research institutions, and enterprises, and build a distinctive talent cultivation system for materials science and engineering.
Develop talent introduction plans, improve flexible talent recruitment and utilization mechanisms, and increase the introduction of high-level talents. Establish a flexible talent management mechanism, coordinate the advancement of talent team building, reasonably encourage and support scientific and technological personnel in innovation and entrepreneurship, provide a good ecology and environment for the cultivation of innovative teams and talents, and enhance original innovation capabilities through "intelligent leadership."
Response Three: Develop biodegradable plastics to promote sustainable development.
Biodegradable materials are an important way to solve plastic waste pollution and are a major trend in the future development of the industry. With the continuous advancement of plastic restriction and ban policies in various countries, the potential demand for biodegradable plastics is enormous. It is recommended to pay high attention to and accelerate the research and development, industrialization, and application of biodegradable materials, to accurately grasp the main attack direction to achieve sustainable development in the plastic industry.
Specifically, focus on developing starch or polylactic acid modified polyethylene and polypropylene to make them biodegradable polyolefin materials, including biodegradable polyesters such as polylactic acid and polybutylene succinate/terephthalate, polybutylene succinate, and polybutylene succinate/terephthalate.
Response Four: Strengthen "production, learning, research, and application" cooperation to improve technology transfer and application efficiency.
It is recommended that production enterprises strengthen communication and cooperation with research institutions, higher education institutions, and application terminals, targeting clear application needs, leveraging respective advantages, and building a "community of interests" for research, development, and production. Jointly carry out research on "bottleneck" technologies, short-board technologies, and disruptive technologies, and build necessary pilot test facilities to improve the efficiency of results transformation.
Build a number of high-level, open public innovation platforms and innovation alliances, focusing on national key projects and strategic emerging industries in fields such as new energy and advanced manufacturing, to construct a complete and efficient technology innovation chain that closely connects research, design, engineering, production, and market.
03
Problems facing the development of high-performance synthetic resins in our country
(1) Technology and equipment are relatively backward, production technology maturity is not high, and product market awareness is low.
Limited by foreign patents, especially polyvinylidene chloride, which has long been listed as a national strategic material, the core technology in the field of high-performance synthetic resins in our country is constrained by others, and the level of technology and equipment needs to be improved. Domestic products are in the stages of research and development, trial production, and application promotion, but the maturity of production technology is not high, and there is still a gap in product quality stability compared to foreign products; at the same time, market awareness is low, as domestic companies tend to use imported polybutene-1 materials to produce good medical devices.
Domestic EVA product brands are relatively single, mainly low to mid-end, with a low market share, while the vast majority of good products still rely on imports. Due to the inability to obtain reliable market verification and timely feedback, the research and development and application pace of high-performance synthetic resins in our country has been hindered, forming a vicious cycle to a certain extent.
(2) Some good products still lack domestic technology, and many products rely on imports.
Taking metallocene polymerization technology as a typical example, our country began organizing national technological breakthroughs in the 1990s, but currently, whether in catalyst structural design, polymerization processes, or industrial scale and product models, it is difficult to meet market demand, with the self-sufficiency rate of metallocene polyolefins being less than 30%. Domestic EVOH resin synthesis has not yet been industrialized; although pilot plants have been established and products have begun trial use, there is still a long way to go before industrial production. In addition, the preparation of membrane materials is also a core technology that has not yet been mastered, such as high-quality PVB films for laminated glass, PVDF binders for power batteries, ion exchange PVDF membranes, piezoelectric films, dielectric films, etc., which basically rely on imports.
(3) Weak basic research in the industry and insufficient independent innovation capability.
The domestic entry into the high-performance synthetic resin field is relatively late, coupled with low research and development investment, resulting in weak basic research in the industry and a lack of innovative talents, especially leading talents. The disconnection between product research and development and application leads to a slow process of promoting new materials. The gap can be reflected in the number of patent applications; for example, in the field of epoxy resins for electronic packaging, Japanese companies account for as much as 68% of global patent applications, American companies about 13%, while domestic companies only account for 6%. The weakness of technological research and development results directly reflects the lack of independent innovation capability.
(4) Insufficient efforts to solve the environmental pollution problem caused by waste plastics.
Due to the difficulty of degrading conventional synthetic resins, the environmental pollution problem caused by the arbitrary disposal of plastic products after use is becoming increasingly serious. Developing waste plastic recycling and biodegradable materials has become a common effort for humanity.
As a major producer and consumer of plastics in the world, our country generates approximately 4.2×10^7 t/a of waste plastics, with packaging applications accounting for 59%; however, the recycling rate of waste plastics is less than 10%, and recycling mainly relies on physical regeneration. Compared with international practices that combine physical regeneration, energy recovery, chemical reduction, and use as solid fuel, the technical content and added value of the processing process are relatively low. In terms of biodegradable materials, there are practical problems in the country such as small device scale, few varieties, and high costs.
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