Views: 224 Author: Vｉｃｋｅｙ Publish Time: 2023-11-02 Origin: Site
In 1849, urethane was created for the first time. Wurtz and Hoffman reported a reaction involving an isocyanate and a hydroxyl compound during those years. Dr. Otto Bayer modified this reaction for a commercial application in 1937. Before this time, polyester-based urethane polymers had gradually supplanted nylon, which had been the material of choice for the industrial world. The Second World War led to a reduction in the use of primary materials like rubber because of scarce resources. This, in turn, facilitated the development of polyurethane materials for coatings, fibres, and foams.
Polyurethanes, one of the most significant polymer classes, are used to make a wide range of products used in modern living spaces. They belong to the polymer group that contains diisocyanate and diol groups in their structures in varying amounts and combinations. The low labour and energy requirements of the process used to obtain polyurethane from liquid monomers account for its popularity among the polymer group. Additionally, it creates a common product group that includes rigid thermoset foams and soft, linear elastomers.
When the right catalysts and additives are present, a poliol and a diisocyanate react to form polyurethane.
Types of Polyurethane Foam
The polyurethane systems are mixed at a specific rate to create polyurethane foam. This substance is used to insulate against high temperatures, sounds, or water.
Polyurethane foams come in a wide variety of varieties depending on characteristics like surface roughness, flexibility, and hardness. Its ability to be produced in desired sizes and forms has led to its widespread use. A structural division of polyurethane foams can be made into four categories: semi-rigid, flexible, rigid, and elastomer variants.
What Distinguishes Rigid Polyurethane Foam From Flexible Polyurethane Foam?
Flexible polyurethane (PUR) foams are open-cell, chemically or physically foamed copolymers formed by diisocyanate containing two or more NCO groups and poliols containing two or more OH groups linked by urethane groups. They may also be described as limited-reshaping and stretching open-cell polyurethane foams. Flexible polyurethane foams are not only incredibly comfortable, but they're also robust and light. They are employed in a wide range of industries, particularly the automotive, furniture, and bed industries.
Rigid polyurethane foams have a much lower thermal conductivity coefficient (lambda) value than insulation materials like wood, rock wool, and polystyrene. This is because they have more closed cells and insulation gases in them. As a result, rigid polyurethane foams provide significantly better thermal insulation than other types of insulation. It is used in a wide range of industries, from the creation of wood-like products for decorative purposes to the thermal insulation of buildings, heaters, and coolers.
In Which Industries Is Polyurethane Used?
A lot of different diisocyanates and polyols can be used to make polyurethane. This means that a lot of different products can be made to meet the needs of different industries and applications. Its rigid and flexible structure, coupled with ease of physical processing and shaping, make it suitable for widespread use in industrial settings.
Foam made of polyurethane has a low coefficient of heat conductivity. Polyurethane foams offer superior insulation as a result. In many industries, such as food preservation in the refrigeration sector and energy and heat consumption in buildings, it is chosen more often than conventional products as an insulating material.
Polyurethane material is preferred over conventional products primarily because it can be used to create products with a wide range of properties, forms, and sizes by varying the raw materials and ratios used.
In the footwear industry, polyurethane is highly favoured due to its ability to meet the primary requirements for producing slippers, insoles, and soles: comfort, flexibility, durability, and lightness. It is used in many different applications, such as the creation of worker shoe soles that need to be extremely flexible and durable, as well as the production of low-density slipper soles.
The primary purpose of polyurethane in buildings is to provide thermal insulation. It retains heat in its surroundings because it is airtight and thermally insulated. It is made as sheets, sandwich panels, pipe sections, and spray polyurethane foams for use in construction. Because of its low conductivity, polyurethane foam guarantees energy savings and improves building insulation performance.
Polyurethane ensures fire safety. The product is categorised as belonging to fire class E (almost non-flammable material) in accordance with the latest European standards. Buildings become more fire-resistant as a result of this. Polyurethane is also used in construction as a coating, sealant, adhesive, and filler material. Polyurethane-based materials can therefore be used in nearly every aspect of a building, from the roof to the foundation.
In the furniture industry, polyurethane is frequently chosen because of its durability, moldability, dye affinity, light weight, and ease of application.
Visco polyurethane foams are used to make mattresses and pillows; HR (High Resilience) polyurethane foams from the flexible polyurethane foam family are used to make office chairs; and rigid polyurethane foams are used to make wood-like decoration products for the furniture industry.
The primary factors contributing to polyurethane's growing market share in the automotive sector are its affordability in terms of both production and assembly, light weight, impact resistance, adaptability to various application conditions, and resistance to corrosion. Car components like bumpers, armrests, consoles, and steering wheels are made from integral polyurethane foams, particularly those belonging to the polyurethane foam family. Furthermore, HR foam systems from the same family are widely used in the manufacture of automobile seats, and flexible polyurethane foams are widely used in the sound insulation of automobiles. Polyurethane's ability to seal makes it suitable for use as a sealing material in cable sheath manufacturing.
Polyurethane finds application in the heating industry as thermal insulation for solar panels and boilers and in the cooling industry as industrial and residential refrigerators, cold rooms, and refrigerator trucks. Because of their excellent insulation qualities and low thermal conductivity, rigid polyurethane foams help to maintain the proper temperature in these products while using less energy and offering great efficiency.
Aircraft use polyurethane in a variety of applications. The comfortable ride that passengers enjoy on aeroplanes is made possible by the use of flexible polyurethane foams. Polyurethane coatings are used in aircraft cabin walls, ceilings, upper compartments, and toilets because of their high abrasion resistance. Furthermore, polyurethane foams are the material of choice for sealing in aeroplanes.
Military materials are supposed to be long-lasting and resistant to adverse conditions. For these materials, high performance, comfort, and durability are crucial.
In the defence industry, polyurethane foams are frequently utilised in the manufacturing of impact pads, tactical helmets, and combat boot soles due to their lightweight, high abrasion resistance, and flexibility.
Because of its many benefits, including high flexibility, high comfort coefficient, adjustable hardness range, and long service life, polyurethane is preferred in the production of medical parts. Many medical products benefit from the ergonomic qualities provided by polyurethane, which is resilient and can return to its original shape.
Because polyurethane foam is lightweight and flexible, it is also used in the production of packaging. Polyurethane foam is typically preferred by companies that produce small, light, or impact-sensitive products when it comes to packaging. Many delicate parts in the electronics and automotive industries are packaged using polyurethane foam. Because it can be produced in the exact dimensions and hardness required based on the size and type of products to be packaged, polyurethane foam is preferred in the packaging industry.
In order to provide thermal insulation for engines in ships, boats, and yachts, polyurethane foam is utilised. For this, stiff polyurethane foams, rubber binders, and polyurethane coatings are utilised. The boat's hull is shielded from water, weather, corrosion, and other elements that can harm hydrodynamics and shorten the boat's lifespan by virtue of polyurethane's strong mechanical and resistance qualities. Boats with polyurethane insulation also have minimal noise levels thanks to their ability to block out sound.