Introduction of foaming agent for polyurethane rigid foam used in construction field
With the increasing requirements of modern buildings for energy saving and environmental protection, the thermal insulation performance of building materials becomes more and more important. Among them, polyurethane rigid foam is an excellent thermal insulation material, with good mechanical properties, low thermal conductivity and other advantages, so it is widely used in the field of building insulation.
Foaming agent is one of the main additives in the production of polyurethane hard foam. According to its action mechanism, it can be divided into two categories: chemical foaming agent and physical foaming agent.
Classification of foam agents
A chemical foam agent is an additive that produces gas and foams polyurethane materials during the reaction of isocyanates and polyols. Water is the representative of the chemical foam agent, which reacts with the isocyanate component to form carbon dioxide gas, so as to foam the polyurethane material. Physical foaming agent is an additive added in the production process of polyurethane hard foam, which foams polyurethane materials through the physical action of gas. Physical foam agents are mainly low-boiling organic compounds, such as hydrofluorocarbons (HFC) or alkane (HC) compounds.
The development process of foam agent began in the late 1950s, DuPont company used trichloro-fluoromethane (CFC-11) as polyurethane hard foam foaming agent, and obtained better product performance, since then CFC-11 has been widely used in the field of polyurethane hard foam. As CFC-11 proved to damage the ozone layer, Western European countries stopped using CFC-11 by the end of 1994, and China also banned the production and use of CFC-11 in 2007. Subsequently, the United States and Europe banned the use of CFC-11 replacement HCFC-141b in 2003 and 2004, respectively. As environmental awareness increases, countries are starting to develop and use alternatives with low global warming potential (GWP).
Hfc-type foam agents were once substitutes for CFC-11 and HCFC-141b, but the GWP value of HFC-type compounds is still relatively high, which is not conducive to environmental protection. Therefore, in recent years, the development focus of foam agents in the construction sector has shifted to low-GWP alternatives.
Pros and cons of foam agents
As a kind of insulation material, polyurethane rigid foam has many advantages, such as excellent thermal insulation performance, good mechanical strength, good sound absorption performance, long-term stable service life and so on.
As an important auxiliary in the preparation of polyurethane hard foam, foaming agent has an important impact on the performance, cost and environmental protection of thermal insulation materials. The advantages of chemical foaming agent are fast foaming speed, uniform foaming, can be used in a wide range of temperature and humidity, can obtain a high foaming rate, so as to prepare high-performance polyurethane rigid foam.
However, chemical foam agents can produce harmful gases, such as carbon dioxide, carbon monoxide and nitrogen oxides, causing pollution to the environment. The advantage of physical foam agent is that it does not produce harmful gases, has little impact on the environment, and can also obtain smaller bubble size and better insulation performance. However, physical foam agents have a relatively slow foaming rate and require higher temperature and humidity to perform at their best.
As a kind of insulation material, polyurethane rigid foam has many advantages, such as excellent thermal insulation performance, good mechanical strength, good sound absorption performance, long-term stable service life and so on.
As an important auxiliary in the preparation of polyurethane hard foam, foaming agent has an important impact on the performance, cost and environmental protection of thermal insulation materials. The advantages of chemical foaming agent are fast foaming speed, uniform foaming, can be used in a wide range of temperature and humidity, can obtain a high foaming rate, so as to prepare high-performance polyurethane rigid foam.
However, chemical foam agents can produce harmful gases, such as carbon dioxide, carbon monoxide and nitrogen oxides, causing pollution to the environment. The advantage of physical foam agent is that it does not produce harmful gases, has little impact on the environment, and can also obtain smaller bubble size and better insulation performance. However, physical foam agents have a relatively slow foaming rate and require higher temperature and humidity to perform at their best.
Future development trend
The trend of foaming agents in the future building industry is mainly towards the development of low GWP substitutes. For example, CO2, HFO, and water alternatives, which have low GWP, zero ODP, and other environmental performance, have been widely used in the production of polyurethane rigid foam. In addition, as the building insulation material technology continues to develop, the foaming agent will further develop more excellent performance, such as better insulation performance, higher foaming rate, and smaller bubble size.
In recent years, domestic and foreign organofluorine chemical enterprises have been actively searching and developing new fluorine-containing physical foaming agents, including fluorinated olefins (HFO) foaming agents, which are called the fourth generation foaming agents and are a physical foaming agent with good gas phase thermal conductivity and environmental benefits.
Post time: Jun-21-2024