The modern construction market is ready to offer its customers both materials with many years of use and a stable reputation, as well as a whole list of polymers that have come to the market not so long ago and are still only gaining the recognition of customers. It is to this group that polyurethane foam is attributed.
What is polyurethane foam?
Specialists attribute this modern building material to the group of gas-filled plastics. Polyurethane foam (PUF) consists of an inert gas phase of more than 85%. The scope of this material is wide and diverse. However, tough debates over whether polyurethane foam is harmful to health have not subsided for many years. The most discussed from this point of view include issues of the behavior of the material during combustion and the release of toxic components when heated.
Material History
The birth date of polyurethane foam can be called with certainty 1937, when a small group of scientists from the laboratory in Levenkusen synthesized material with unusual properties. Depending on what was the mixing coefficient of the components of the new material and how quickly the reaction went, the properties of polyurethane foam were fundamentally different. On the one hand, the material was elastic and flexible, but rather unstable to breaking loads. On the other hand - strength, hardness, density, but brittleness when bent. The material opened up extremely broad prospects, but World War II significantly slowed down their execution. However, since the 60s of the last century, the production of PPU began to develop at a rapid pace.
The composition of the PUF
The main components that make up the polyurethane foam and are necessary for the formation and attachment of polymer chains are polyol (component A) and polyisocyanate (component B). Sometimes domestic manufacturers can add another component to the polyol - a catalyst. The main components of polyurethane foam have a specific smell and are a liquid of a fairly thick consistency with shades from light yellow to dark brown.
Polyol during long-term storage tends to exfoliate, so it is recommended to mix it before use. The polyisocyanate interacts with water - upon contact, crystallization begins. During prolonged storage in the open air, a film forms on the surface of the material. In terms of its component composition, PPU can be of two types - for spraying and for pouring.
Biogenic properties
Polyols and polyisocyanates used for the production of polyurethane foam are petroleum products. However, it is known that the components of polyurethane foam can be produced from vegetable oils. The best option for this purpose is castor oil. The polyol component can also be obtained from sunflower, soy, and rapeseed oils. However, the cost of this raw material is quite high and production is not economically feasible. Biogenic PPU materials are produced in small volumes and are used to solve very narrow specific problems.
PPU properties
Polyurethane foam, produced by domestic and foreign manufacturers, has a number of both positive and negative characteristics.
The low thermal conductivity of the material (0.019 - 0.03 W / m), almost complete vapor impermeability, and water resistance make polyurethane foam an excellent heat and year insulator. The same can be said about sound insulation. High adhesion coefficient makes it possible to apply PU foam on almost any surface.
However, polyurethane foam is not only characterized by positive qualities. Damage to human health can be caused during the burning of PPU (in the presence of a direct source of fire, the material burns). In addition, polyurethane foam releases toxic substances into the atmosphere - formaldehydes. Polyurethane foam, whose components interact with air and water, is unstable to sunlight. Over time, it darkens and falls off.
Scope of PPU
This modern building polymer has been widely used in various fields of human activity. Its widest scope is in construction: thermal insulation, acoustic and waterproofing of civil and industrial facilities for any purpose (residential, country houses, workshops, warehouses, hangars, etc.). Due to the low thermal conductivity, polyurethane foam is used to warm not only roofs, but also walls both inside and outside buildings. PPU sandwich panels are indispensable in the construction of prefabricated construction sites.
Polyurethane foam with a density of 30-86 kg / m³ (rigid polyurethane foams) are used as noise and heat insulation material. Material with a density of 70 kg / m³ has a dense structure, does not pass water and is successfully used for waterproofing works.
In the production of refrigeration equipment PPU is used as a cold insulator. The shoe industry uses material for the manufacture of various elements of shoes and arch support.
However, there are areas where the use of a material such as polyurethane foam is very doubtful. Lining material and fillers for upholstered furniture, mattresses, pillows, etc. can cause harm to health. (polyurethane foam with a density of 5-40 g / m³ - soft foam blocks). Although manufacturers of PUFs claim that the material is environmentally and biologically neutral, using it as a filler for children's toys can also make parents think about the health of their children.
Sleep in the arms of PPU ...
It will be about such items of bedding as mattresses made of polyurethane foam. The harm, and quite serious, can be caused by inhaling the fumes of complex volatile chemical compounds (about 30 species), the most dangerous of which are phenol and 2-ethylhexanoic acid. Moreover, new mattresses filled with polyurethane foam emit 5-6 times more hazardous substances into the atmosphere than old ones. The vapor concentration of these substances is comparable to the emissions from the new laminate flooring.
Assurances about the safety of mattresses filled with polyurethane foam are doubtful for the simple reason that at the stage of their manufacture they use resins, catalysts, solvents, active chemical components (phenol!).
Is the threat of phenol great?
Phenol is considered a toxic substance for the reason that it emits toxic fumes, and this process can continue for years without reduction or loss of toxicity. This chemical element can cause disruption of the most important systems of the human body: respiratory, nervous, cardiovascular. The result may be headaches, loss of consciousness, impaired coordination of movements. The functioning of the kidneys and liver may also be impaired. Constant contact with phenol and its fumes can cause the emergence of such formidable diseases as asthma, infectious pulmonary pathologies, and allergies.
According to scientists involved in research in this area, the use of polyurethane foam for the manufacture of children's furniture, mattresses, toys is unreasonable. PPU can very well be replaced with safer materials. If parents are concerned about the health of their children, they need to be very careful about choosing toys and mattresses for them, in which polyurethane foam can be used as a filler. The bulk of civilized countries banned the use of phenol for the manufacture of everyday goods.
What else is harmful?
Products made of polyurethane foam are widely used in many areas of human life. Polyurethane foam and foam board based on polyurethane foam adversely affect the lungs, skin, eyes. Thermal insulation plates made of polyurethane foam release toxic polyisocyanate compounds into the air that can cause allergies or asthma. When the PUF-plates are heated with heating batteries or sunlight, the release of polyisocyanate is enhanced.
In the event of a fire, the PUF burns and emits toxic gases, which is an additional source of danger and threat to life. However, it is worth noting that recently non-combustible types of polyurethane foam obtained by introducing special additives into their composition are increasingly being used. Such a polyurethane foam practically does not harm health.
So where is the truth?
Polyurethane foam - what is it? Harm or good? A huge number of places of application of polyurethane foam in various spheres of human life does not allow us to give an unambiguous answer to this question. For the construction industry, this is certainly a huge benefit. The ability to make a mixture and apply PUF on the insulated surface directly at the construction site reduces associated costs and allows you to create a monolithic PUF surface without cracks during installation and cold bridges. Thermal insulation of main pipelines, insulation of low-temperature pipelines of the chemical industry is also hardly possible at the moment with the same efficiency that polyurethane foam provides.
However, the use of this material in the production of goods for people (and for children in particular) seems to many experts in this field not entirely justified. The release of toxic substances can have a negative effect on human health. Until 2003, the manufacturing technology of domestic components for the production of PUFs provided for the use of highly volatile ether compounds. Today, manufacturers claim that they abandoned this technology. Within 3 days after application, the material is freed from the small amount of gases remaining after the reaction of the components, and then polyurethane foam is environmentally friendly.
In general, in each particular case, before using PPU products, one must take a sensible approach to assessing the pros and cons of using this material in one or another sphere of life.