You might not know its name, but you’ve probably encountered Polybutene-1 (PB-1) in your daily life. This remarkable polymer is quietly revolutionizing everything from the pipes in your home to the packaging of your favorite snacks. And it’s about to become even bigger.
The Power of PB-1: A Material with a Golden Touch
Imagine a material that’s incredibly strong, resistant to heat and chemicals, and environmentally friendly. That’s PB-1 for you. This linear polymer, made from 1-butene monomer, boasts a unique combination of properties that make it a true standout in the world of plastics. It’s so impressive, it’s been nicknamed “gold in plastics.”
Beyond Pipes: PB-1’s Expanding Horizons
While PB-1 pipes are already a common sight, this versatile material is making waves in many other industries. Here’s a glimpse into the exciting world of PB-1 applications:
- Food Packaging: PB-1’s strength and heat resistance make it ideal for multi-layer composite films used in food packaging. Say goodbye to flimsy plastic bags and hello to durable, high-temperature-resistant packaging that keeps your food fresh and safe.
- Cables and Fibers: PB-1’s excellent insulation properties and low dielectric constants make it a perfect choice for cables and fibers. Expect more reliable, durable, and stable cables and fibers that power our modern world.
- Plastic Modification: PB-1 is a game-changer for enhancing the performance of other plastics like PP and PE. It improves processing and increases film strength, making these materials even more versatile and useful.
- Hot Melt Adhesives: PB-1 is a rising star in the world of hot melt adhesives. Its exceptional properties make it ideal for applications in the shoe industry, automotive industry, and beyond.
The Future is Bright: PB-1’s Unstoppable Rise
While PB-1 has been around for a while, its full potential is just beginning to be realized. As demand for high-performance, environmentally friendly materials continues to grow, PB-1 is poised for a major breakthrough. With its exceptional properties and diverse applications, PB-1 is set to become a cornerstone of the future, shaping the world around us in exciting and innovative ways.
01 Basic overview
Poly-1-butene (PB-1) is a linear polymer with a certain isotactic structure and crystallinity produced by the polymerization of 1-butene (1-Bt) monomer under the action of a catalyst. Compared with other polyolefins, PB-1 has slightly rubbery properties, good mechanical properties, good chemical stability, and is green and environmentally friendly. It can be made into sheets, films, pipes and containers, etc., and has a wide range of uses.
Polybutene is an inert polymer with a translucent, colorless and odorless appearance. It has a regular molecular structure. It has excellent chemical resistance, aging resistance and electrical insulation properties, and has unique creep resistance . , environmental stress cracking resistance (ESCR) and high impact resistance . Not only that, poly-1-butene resin, with its unique crystallization behavior, can provide a long and easily adjustable opening time, high bonding strength and creep resistance, good low-temperature flexibility and thermal stability, It has a relatively wide operating temperature and viscosity range, and also has good adhesion to low temperature and non-polar substrates.
Polybutene 1 (PB-1) is known as the ” gold among plastics ” due to its excellent physical and chemical properties and is currently one of the most cutting-edge chemical materials in the world . PB-1 was first polymerized by Natta and colleagues in 1954. In the early days, a chemical agent system composed of organoaluminum compounds and transition metal salts/halides was used. With the development of chemical agent systems, poly-1-butene resins with high stereodirectivity and high mechanical properties have been gradually developed. However, poly-1-butene has not been able to achieve large-scale commercial production and application like PP and PE, mainly for the following reasons:
(1) Compared with ethylene and propylene, polymer-grade 1-butene has low yield and high cost;
(2) The synthesis process is complex, the process energy consumption is high, and the economy is poor;
(3) Poly-1-butene crystals undergo crystalline transformation, and the transformation cycle is long, making it difficult to control the size of the product, which is not conducive to processing and application.
02 Three-dimensional structure and crystal structure
The structural formula of polybutene-1 is -(H2C-CH(C2H5))n-. Due to the different spatial arrangements of the ethylene side chains along the main chain, there are three different polybutene structures: isotactic, atactic and syndiotactic. .
The melting point of syndiotactic poly-1-butene is 57°C; atactic poly-1-butene is an amorphous polymer. At present, there are no reports on development and application; as a semi-crystalline polymer, poly-1-butene with an identical structure has outstanding thermal creep resistance, environmental stress cracking resistance (ESCR) and good Toughness , when the isotacticity is 98~99.5%, it can meet the requirements of industrial products . It is an excellent material for the production of pipes .
Isotropic poly-1-butene (iPB-1) is a polymorphic polymer with five crystal forms: I, II, III, I’, and II’. Among them , the most important one that can be used in practical applications is the crystal form. Form I and Form II . Among them, the most stable one is crystal form I. Crystal form II is in a thermodynamically unstable state . Isotactic polybutene-1 is melted and then cooled and crystallized under normal pressure to form crystal form II. Crystal form II will gradually transition to crystal form I, this change is an irreversible transformation. Crystalline form III is stable at room temperature, forms crystalline form II when close to the melting point, and continues to transition to crystalline form I. iPB can form crystal form I’ when solution crystallization occurs in a certain solvent or melt crystallization occurs under high pressure conditions. Crystal form I’ shows an X-ray diffraction pattern similar to crystal form I, and they have the same crystal structure. cell parameters. Another crystal form II’ has rarely been reported.
03 Properties of poly-1-butene
Highly isotactic polybutene-1 (i-PB) is a special semi-crystalline polyolefin thermoplastic. It has good mechanical properties, excellent toughness, outstanding heat resistance, creep resistance, and wear resistance. and environmental stress cracking resistance . Polybutene-1 is polymerized from the monomer butene-1. It is an ecological carbohydrate with the advantages of temperature resistance, chemical stability, durability, etc. It is non-toxic, tasteless and odorless. It is currently the world’s most popular polybutene-1. One of the most cutting-edge chemical materials in the world .
Polybutene-1 (PB-1) is an inert polymer that not only has good chemical resistance and dielectric properties, but also has excellent toughness and mechanical strength. Compared with other types of polyolefins, PB-1 was found to have the best environmental stress cracking resistance. Compared with polypropylene and polyethylene, PB-1 has higher creep resistance, and when the stress is lower than the yield point, PB-1 can still maintain very good creep resistance at 110°C. The wear resistance of PB-1 is comparable to UHMWPE (ultra-high molecular weight polyethylene), and it is suitable for making transmission pipes, metal pipe linings, irrigation pipes, slurry transportation pipes, etc. Compared with polypropylene and polyethylene, its modulus is lower and the material is soft. It is the preferred material for making flexible pipes.
04 Bulk polymerization process
The first industrial production of poly-1-butene products was achieved as early as 1964. However, due to the difficulty of its polymerization technology, the production cost of PB-1 products was high, which restricted the industrialization of PB-1.
The synthesis of poly-1-butene basically uses similar catalyst systems and production processes as polypropylene (PP), including liquid phase bulk method, slurry method, gas phase method, etc. The difference is that PB-1 can be synthesized in its monomer 1 -Dissolve or swell in butene.
The liquid phase bulk method is the mainstream process for producing PB-1 today. Liquid phase 1-butene (1-Bt) is used as the reaction monomer and medium. According to the dissolution of the polymer in the medium, it can be divided into: homogeneous phase Ontological method and heterogeneous ontological method.
1. Heterogeneous ontology method
The early 1-butene polymerization process was mainly based on the slurry method. Petro-Tex Company and Chemische Werke Hüls Company first realized commercial production of isotactic polymerization of 1-butene products in the early 1960s. However, these two sets Due to the shortcomings of the process itself, the production equipment will not be put into production for more than 10 years. Mitsui Chemicals built a heterogeneous bulk method industrialized device based on the slurry method (called the Hüls process) developed by the German Chemische Werke Hüls Company.
When using the heterogeneous bulk method, the polymerization temperature needs to be controlled not to exceed 30°C (when it is higher than 30°C, the solubility of poly-1-butene in liquid 1-butene increases, making the polymer particles easy to adhere). Limited by this, the catalytic efficiency of the heterogeneous bulk method is not high and the productivity is low, resulting in a low global share of Mitsui Chemicals’ products. At the same time, in order to prevent the high ash content of the polymer from affecting product performance, the slurry coming out of the polymerization unit needs to be washed with water to remove catalyst residues. The washed slurry is centrifuged, and the liquid phase is distilled to recover unreacted 1-butene (the residue from the distillation process is atactic poly-1-butene), while the solid phase (i.e., polymer particles) is isotactic. Polybutene with a strength of 99%, but this process results in increased costs.
With the successful development of new Ziegler-Natta catalysts, catalyst performance has been greatly improved, and the heterogeneous bulk polymerization process has also progressed. Domestic Qingdao University of Science and Technology cooperated with domestic polyolefin manufacturers (Dongfang Hongye, Jingbo Petrochemical, etc.) to transform the intermittent bulk polypropylene device and develop a commercial technology for the production of poly1-propene through the heterogeneous bulk process. In order to ensure the effectiveness of the polymerization process, a segmented method or a continuous sequential polymerization process is adopted. First, polymer particles (poly-1-butene, polypropylene or polypropylene) are prepolymerized at a lower temperature (below 35°C). Ethylene, etc.), then rise to a higher temperature for polymerization, and finally obtain poly-1-butene product.
2. Homogeneous ontology method
In 1968, Mobil Oil developed the homogeneous bulk 1-butene polymerization technology and used this process to build a small-scale production unit in Taft, Louisiana. In 1972 Witco Chemical took over the unit. At the end of 1977, Shell acquired Witco Chemical’s poly-1-butene business. Therefore, this process is also called the Mobil-Witco-Shell process and is the basis of LyondellBasell’s current poly-1-butene process technology.
Mobil-Witco-shell process uses TiCl4/MgCl2/EB The catalyst system uses triethylaluminum as a cocatalyst, hydrogen as a chain transfer agent, the polymerization temperature is 43~90°C, and the reaction pressure is 0.93MPa (to ensure that 1-butene is in the liquid phase). During the polymerization process, excess 1-butene is used. Proceed in olefin monomer to generate The polymer is completely dissolved in liquid 1-butene to form a homogeneous solution (the content of the polymer does not exceed 40%, mass fraction). This solves the problem of agglomeration during the slurry polymerization process, excessive catalyst residues in the polymer, Problems such as low polymer specifications. But at the same time, the separation of the polymer and the unreacted monomers requires complex and energy-intensive flash evaporation and devolatilization processes, which increases the production cost and difficulty.
With the advancement of technology, the activity of the catalyst has been greatly improved, the ash content in the polymer has been greatly reduced, and the water washing process has been omitted from the process flow. In 2002, Taft’s polybutene-1 production unit was taken out of service. In 2000, Shell’s polybutene-1 business was transferred to Basel Polyolefins. In 2004, Basel Polyolefins built a poly-1-butene production unit in Moerdijk, the Netherlands, with a capacity of 45,000 tons/year. In 2008, the capacity was expanded to 67,000 tons/year. This unit is currently the largest in the world. Poly-1-butene production unit.
In recent years, the Sinopec Beijing Research Institute of Chemical Industry team has conducted research on the preparation technology of higher isotactic polymerization of 1-butene. In 2021, Sinopec Zhenhai Refining and Chemical built a 3,000-ton/year semi-industrial unit, which has successfully opened up the entire process and produced poly-1-butene products. The device can perform 1-butene homopolymerization or 1-butene/ethylene random copolymerization, using high-performance catalysts developed by Sinopec. The catalyst has the characteristics of high activity and good stereoorientation ability, and does not require deashing operations such as water washing. In this process, the polymerization process adopts double-kettle series operation (the composition of the reactants in each polymerization pot can be controlled independently), hydrogen is used as a chain transfer agent, and the polymer generated during the polymerization process is dissolved in liquid 1-butene to form a homogeneous solution. The polymer liquid obtained during the polymerization process enters the devolatilization unit to separate the polymer and unreacted monomers and deeply remove VOC components. After devolatilization, the polymer melt is sent to the granulation unit, where necessary additives are added to obtain polymer pellets. Unreacted monomers are recycled after condensation, distillation and purification.
Currently, there are only a few companies that can carry out industrial production of poly-1-butene, including LyondellBasell, Japan’s Mitsui Chemicals, Korea’s Aecon, Shandong Hongye and Jingbo Petrochemical. The global total production capacity is growing slowly, and the production technology is disclosed. There was little coverage. Domestic related technical and product barriers have never been overcome, and domestic high-end PB-1 technology and products have long been monopolized by foreign countries.
05 Catalyst system
The synthesis catalysts for poly-1-butene mainly include Ziegler-Natta catalysts and metallocene catalysts.
1. ZN catalyst
With the support of Ziegler-Natta catalyst and the development of new electron donors, its catalytic performance has been greatly improved, with excellent activity and stereoregularity, good product form, and no need for post-treatment. ZN catalysts are currently used in industry.
2. Metallocene catalysts
Since the 1980s, methylaluminoxane (MAO) has been used in the synthesis of PB. Compared with Z-N catalysts, metallocene catalysts have the characteristics of a single active center, so that the relative molecular weight, distribution and crystal structure of the polymer can be accurately controlled. However, the cost is higher and the relative molecular mass of synthesized PB is lower. Development is slow .
06 Poly-1-butene products
Poly1-butene (PB-1) can be divided into isotactic PB-1 (iPB), syndiotactic PB-1 (sPB) and atactic PB-1 (aPb) according to the degree of polymerization. PB-1 series composite materials include PB-1 thermoplastic elastomer (PB-TPE) and polybutylene-1 alloy (PBA), etc.
At present, the widely used PB-1 materials mainly include iPB, PBA and PB-TPE . iPB is a semi-crystalline plastic with excellent thermal creep resistance and environmental stress cracking resistance. It is an ideal resistant material. As a high-temperature pipe material, PBA overcomes the shortcomings of iPB such as slow molding and unsatisfactory barrier properties. PB-TPE obtains a certain elasticity by reducing the regularity of the molecular chain and can be used as various soft materials.
By controlling the polymerization conditions and adjusting the molecular chain structure of poly-1-butene, poly-1-butene products with different properties can be obtained, forming a full range of grades similar to polyethylene that meet different applications.
Isotactic poly-1-butene (iPB) is the main commercial product . As a typical semi-crystalline polymer, its most prominent features are environmental stress cracking resistance and mechanical strength . Compared with LDPE, its tensile strength can be increased to 6 to 10 times, and its impact strength can be increased to 3 to 4 times. The wear resistance is comparable to UHMWPE. Thermal creep resistance is better than polyethylene and polypropylene. It can be used for a long time in the temperature range of -10~110℃, and is suitable for hot and cold water pipes. In addition to being used in pipes, isotactic poly-1-butene is also used in fields such as films and plastic modifiers. In addition, it is also being explored in fields such as fiber and cable insulation.
1. Pipes
Poly-1-butene pipes have the characteristics of toughness, no rust, wear resistance, no scaling, high temperature and high pressure resistance, non-toxic, and excellent impact performance. Compared with other plastic materials (HDPE, PP, PP-R and PE- X) Compared with poly-1-butene, it has better thermal creep resistance and environmental stress cracking resistance. Poly-1-butene pipes can be used for long-term use at temperatures below 90°C and short-term use at 105~110°C as long as the stress yield point is not exceeded.
The pipe wall of poly-1-butene pipe has low adhesion to the flowing medium and low water flow loss. Compared with metal pipes, the water supply capacity can be increased by 20%. Therefore, in drinking water, hot water transportation, and heating pipes, poly1-butene pipes are an ideal choice. In terms of construction performance, poly-1-butene is similar to PP-R, has plasticity, and can be connected and combined with the same or different types of materials. Polybutene has a simple molecular structure. Waste materials do not produce toxic substances and are easy to be recycled and reused. They do not produce serious ecological and environmental impacts like PVC recycling. They have excellent aging resistance and can be used for more than 50 years under conditions of isolation from ultraviolet rays. .
Although poly-1-butene pipes have the advantages of light weight, good durability, high softness, easy construction, smooth pipe walls and are not prone to scale accumulation, their actual consumption is small (compared to PE pipes and PP pipes). The main reasons are: poly-1-butene pipe raw materials can only be provided by a few companies such as LyondellBasell and Mitsui Chemicals, and the supply is limited; the price of poly-1-butene pipe raw materials is high, and its price is about that of PP-R pipe materials. More than twice.
2. Film
Polybutene can be used to manufacture multi-layer composite films, which have certain advantages in food packaging, high-temperature cooking films and other fields. The dielectric constant of poly-1-butene is similar to that of PP, and films prepared from poly-1-butene can be used as capacitor diaphragms. Poly-1-butene film has good transparency and UV resistance, and is also used in agricultural films.
Commercially, the incompatibility of the molecular structures of poly-1-butene and PE is also used to make films, so that the film products have the properties of easy peeling and strong sealing. When used for heat sealing, no adhesive is needed, the seal can be achieved well, and it is easy to open. It is often used in the field of food packaging. For example, Montell originally used it for easy-to-peel coffee vacuum packaging. Easy-tear films based on poly-1-butene are also used for packaging chemicals and fertilizers.
Currently, easy-tear film products containing PB-1 are mainly made of polyethylene (PE) and polypropylene (PP) as base resins by adding PB-1. Polyethylene films usually add PB-1 into the polyethylene matrix to form an island structure of PB-1 material in the polyethylene matrix, thereby destroying the sealing structure of the polyethylene and achieving an easy-to-tear effect. PB-1 can also be used in BOPP film to achieve an easy-to-tear effect. Typical application examples include ice cream packaging and snack packaging.
3. Cables and fibers
Polybutene has good insulation, low dielectric constant and good electrical properties. It can be used to prepare insulating layers to protect wires and cables, obtain long-lasting stability and reduce electrical losses. Poly-1-butene is blended with high-efficiency flame retardants and conductive and thermally conductive fillers. It has high use value and therefore has good development prospects. Polybutene-based materials can be made into fibers using different preparation methods. Mobil Oil Company has developed fibers with high elasticity and toughness by blending poly-1-butene and propylene-butylene copolymer. Poly-1-butene is also compounded with reinforcing fibers to prepare high-pressure resistant materials.
4. Plastic blending modification
Poly-1-butene can be used to improve the processing and product properties of PP and PE films. Adding a very small amount of poly-1-butene can improve the mechanical and optical properties of the PE film, reduce surface roughness, and increase surface gloss. Improve the strength, tensile modulus, breaking strength and breaking elongation of LLDPE and HDPE films. In addition, blending poly-1-butene with polypropylene can produce dimensionally stable and impact-resistant molded products, and blending with Eucommia gum can produce products with memory effects.
5. Hot melt adhesive
Poly-1-butene resin has good development prospects in the field of hot-melt adhesives. It is mainly used in hot-melt linings, footwear, automobiles, and other industrial bonding and sealing fields. It is especially suitable for glue spraying processes and low-temperature/low-temperature adhesive applications. High-strength/high-strength composite, and does not corrode the adherends (such as metal). For specific applications, PB-1 resin can be blended with other compounding agents (such as tackifying resin, antioxidants, nucleating agents, etc.) to form hot melt adhesive blocks and granules, which are widely used in footwear, automobile and industrial adhesion. Hot melt adhesive is used for sealing; it can also be made into powdery or mesh-like hot melt adhesive for bonding various linings. In addition, adding PB-1 to random poly α-olefin APAO or random polypropylene APP can significantly increase the shear bonding failure temperature of the adhesive and improve the low-temperature performance of the APP adhesive. Moreover, in all these applications, the amount of PB-1 resin added to hot melt adhesive is relatively small, the production and coating energy consumption is small, and it has good competitiveness compared with copolymerized nylon and copolyester.
07 Development and market
Polybutene-1 is one of the most cutting-edge chemical materials in the world. It was polymerized for the first time in the world as early as 1954 by Professor G.Natta of Italy . It was first industrially produced by the German Hess Chemical Company (Huels) in 1964 and produced by Mobil Petroleum Company built a plant in Louisiana, USA, and it was operated by Witco Chemical Company in 1970. In 1977, Shell of the United States purchased all related businesses of polybutene-1 from Witco Company, and through transformation, its production capacity reached 27,000 tons/year. In 2000, Basell decided to establish a production base with an annual output of 45,000 tons/year in Australia. In 2003, Basell’s polybutene-1 production base in Moerdijk, the Netherlands, was officially put into operation. The polybutene-1 products were fully upgraded. By the beginning of 2005, the production capacity reached 50,000 tons/year. Currently, Basell’s total polybutene resin production capacity is 6.7 Thousands of tons/year. In addition, Japan’s Mitsui , South Korea’s Ylem and other companies also have the production capacity of polybutylene-1 materials.
At present, the global PB-1 production equipment is mainly concentrated in the Netherlands, Japan, South Korea and China, with a total production capacity of approximately 250,000 t/a. The world’s annual production and consumption are both around 150,000 tons, and consumption is mainly concentrated in developed countries such as Europe, the United States, Japan and South Korea. It is expected that by 2025, global demand will exceed 200,000 t/a, and the growth in demand will mainly come from emerging markets such as China. my country’s PB-1 industry started late. Although there are already new polybutene plants, product quality and stability still need to be further improved. Due to technical limitations, high-end products are highly dependent on imports.
With the development of my country’s petrochemical industry, C4 resources and C4 separation devices continue to expand, and the development and utilization of 1-butene is becoming increasingly urgent. Moreover, as LLDPE gradually uses high-carbon olefins such as hexene and octene as the second monomer, the utilization rate decreases. A large amount of 1-butene production capacity is idle, and 1-butene resources are burned as liquefied gas, which is a huge waste. Therefore, the research and development of 1-butene as new materials such as poly-1-butene resin has important socioeconomic significance.
To resolve PB-1 Regarding the issue of material import substitution, on the one hand, we should further increase investment in research and development of domestic technology, and strengthen joint research on PB-1 basic theory, high-performance catalyst technology, homogeneous bulk olefin polymerization technology, and polymer deep devolatilization technology; On the other hand, it is necessary to achieve continuous and stable industrial equipment Mass production, improve product quality, reduce production costs, and develop more high-end new PB-1 brands, expand the application fields of PB-1 products, and provide independent key materials for construction pipes, medical and health, food packaging, cables, automobiles and other industries. Provide strong support for controllable and improved market competitiveness.