Polyurethane foam: what is it, composition, characteristics, properties of polyurethane foam

Slowly, but Russians are still saying goodbye to small-sized apartments in Khrushchev-era buildings, where a 3-room apartment is often smaller in area than a modern one-room apartment. More and more large private houses are appearing. At the same time, we are talking not only about cottages in elite villages. As the living space increases, heating costs also increase. Proper thermal insulation of all structural elements of a building can save household finances, and therefore homeowners approach the choice of insulation very responsibly. After all, the slightest mistake is fraught with unpleasant consequences in the future.

Taking into account the increased attention of consumers to the topic of thermal insulation materials, the editors of the StroyGuru website have prepared a series of articles about modern types of insulation materials, their characteristics, advantages and disadvantages, and the best manufacturers. In this work we will tell you everything about polyurethane foam insulation, its liquid version, which among builders is called for short - polyurethane foam.

Definition

To better understand what polyurethane foam is, we will give a brief definition of the material - it is a synthetic foam with a cellular structure. Refers to a section of plastic filled with a special inert gas, and is often used in construction and manufacturing.

Among the undoubted advantages:

• • long-term use;
• • ease of operation;
• • minimal thermal conductivity;
• • excellent adhesion.

This is one of the high-quality insulation materials that is often used to improve the structural features of a house. Some surfaces are covered with gas-filled polyurethane foam of complex shapes. It has a long lifespan and is easy to use on construction sites.

Peculiarities

They are used very widely: rigid - as heat and sound insulation and lightweight form-building elements, elastic - as soft coverings and padding in everyday life and industry, as artificial sponges for washing and dust filters, material for paint rollers and inserts in garments, shock-absorbing package.

Self-foaming self-hardening compounds are popular for use directly on site in construction and mechanical engineering - both industrial multicomponent and household polyurethane foam.

Resistant to all common organic solvents, the frozen mixture can only be removed mechanically. In practical applications, protection from sunlight and other UV sources is required.

Compared to other foamed polymers used in limited areas - rigid polystyrene foam, elastic polyethylene foam, latex foam, microporous rubber, swelling cellulose sponge - the range of use of polyurethane foams is, as a rule, wider.

Polyurethane foam (PPU), composition and properties

It is obtained by mixing two liquid materials:

• • polyisocyanate;
• • polyol.

The substance is whipped, when it hardens, then 90% of the frozen result turns out to be gas. This way the foam can be used for thermal insulation. It stops letting cold and heat through. The final product is structurally different, and the area of ​​use is also different. This depends on the proportion of liquids and additives used.

This is how foam rubber is created - an elastic and soft filler. It is usually used as an interior part for furniture: sofas, armchairs and other upholstered products. The brand depends on two indicators - how dense and hard the foam is.

Density and hardness table

The presence of a fire retardant impurity turns polyurethane foam into rigid polyurethane foam. It has an increased density - from 30 to 85 kg/cm3. When it is ready, it loses its elasticity. But it has many other useful properties:

• • used to reduce noise levels and thermal insulation;
• • for insulation from foundation moisture, if it is above 70 kg/cm3.

For construction purposes, polyurethane foam is prepared from a couple of components:

• • Isocyanate is the basis of the chemical process, an unchanged component.
• • Polyol – varies depending on the purpose.

Such elements affect the reaction rate, how much foam it will foam, what the density and flammability will be in the end.

GOST 307302-2006 confirms that polyurethane foam has a G3 class - what is it: it is considered fire-resistant, self-extinguishing and flame-retardant.

Production

Raw materials for polyurethane foam are products of the petrochemical industry: polyisocyanates and polyols. Also, components for polyurethane foam are made from vegetable oils: castor, rapeseed, soybean, sunflower. Biogenic foam components have not found application in industry, since they require considerable financial investments, and their use is limited to a narrow range of specific tasks.

Chemical reactions take place between petroleum products (polyol and polyisocyanate) mixed in certain proportions. After the first transformations, a small amount of water is added to the reaction mixture, and carbon dioxide begins to be released. The reaction results in foam filled with CO2. The mechanical characteristics and properties of polyurethane, i.e. density and structure, are determined by the size of the chain of gas-filled microgranules, the proportion of the original polymers, and the presence of fire retardant additives.

Varieties

Most enterprises can produce different types:

• • liquid – sold in spray containers;
• • hard – sheets, shells and panels;
• • foam rubber – mats and rolls of finished products.

Thickness and protective properties can vary depending on the purpose. The characteristics allow it to be prepared directly on the construction site. When the proportions of components change, the features change.

Foam rubber

It has a low density from 5 to 35 kg/m3. The scope of application is very wide - from furniture filler to linings in shoes and clothes, they are used to make washcloths and gaskets for doors and windows.

PPU hard

The main place of use is construction. More often it is produced directly on site - this saves resources. Using special equipment, workers mix the components in the required proportions.

This produces ready-made polyurethane foam, which is not afraid of petroleum products and water, but is afraid of organic solvents and other mineral acids. There are more than 30 brands of different purposes and densities. Polyurethane foam can be used in one form for insulation, or in combination with analogues of a different frequency.

The scope of application is wide - from noise and heat insulation of buildings to the insulating layer in refrigeration equipment. Extremely positive reviews.

Liquid

Used for spraying on walls and ceilings. Thanks to its thinner consistency, it became possible to spray it onto walls under pressure to provide insulation. Indispensable if you need to work without weighing down the structure.

Thickness table

Kinds

Experts distinguish three types of polyurethane foam:

Hard

This type of material has high density, hardness and lightness.

Thanks to these characteristics, it is used as acoustic or thermal insulation. Hard polyurethane foam looks like slabs. One of the applications is sandwich panels.

Polyurethane foam (PPU) technical characteristics and properties

In terms of thermal insulation characteristics, foam is superior to many analogues. As a heater it is difficult to find equal. High density and adhesion make the cold insulation capabilities even greater. They depend on the structure of the material. The liquid form has a coefficient of 0.019 to 0.035 W/m K, and the closest similar form, mineral wool, has a coefficient of 0.045 W/m K.

Vapor permeability is also low - closed cells do not let steam inside. For mineral wool, the same indicator is 50 times worse. Foam protects walls and ceilings from harmful influences, maintains the desired temperature inside the rooms and stops water particles from penetrating into the walls. But it is not recommended to use it under liquid or in direct contact with it, as this can cause a hydration reaction.

Comparison with mineral wool

This is the closest analogue, more popular, cheaper and inferior in a number of properties. The compressive strength of polyurethane foam is at the level of 0.3; for mineral wool it is not calculated, since it is a very flexible and obedient material.

Polyurethane foam can absorb no more than 10% of water; mineral wool is not designed for such a load and itself has a constant 4% humidity. It will not resist swelling from liquid, so it is not recommended to use it in residential buildings.

Let's talk about maximum service life. The foam will last at least 40 years, and the level of other substances does not exceed 10. Caked mineral wool simply becomes a harmful gasket that is of no use.

Polyurethane foam does not contain dangerous fumes, formaldehydes and phenols, like its cheaper analogue with 6% of unwanted compounds, and is completely safe. It is resistant to aggressive environments and has excellent resistance to rodents and insects. Polyurethane foam does not release fibers into the air; mineral wool contains an allergen for many people and azone-depleting gases.

Table: 12 characteristics

Depending on the indicator they are divided:

• • C – self-damping;
• • Vehicles – difficult to burn;
• • TV – flame-resistant.

To increase fire resistance, special substances are usually added to the composition. It is important to know exactly which ones you can put, but it is better to entrust this to specialists rather than do it yourself.

Safety

A material is said to be environmentally friendly if only high-quality components and professional equipment were used when pouring the thermal insulation coating. It is equally important that the spraying is done by a qualified craftsman - how he mixes the components affects the safety of the coating. Raw materials for polyurethane foam belong to hazard classes 2 and 3, and after hardening, a material characterized by inertness is formed.

If the proportions of the starting components are chosen incorrectly or the technology for preparing the liquid mixture is violated, the chemicals will not react completely. The result is a pungent, toxic odor that does not dissipate well and causes illness. An experienced craftsman does not make mistakes, making the coating environmentally friendly and non-flammable.

During the mixing of raw materials, toxic formaldehyde, benzene, phenol and toluene diisocyanate are formed. After applying the “coat,” they evaporate within a day and are no longer released, unlike foam plastic or mineral wool. Opponents of the chemical compound focus on the destruction of the substance during the combustion process. They state that at a temperature of 180 ° C, ethylene, formaldehyde, nitrogen and carbon oxides, and isocyanates are released. In reality, such temperature conditions are not compatible with human life, so there is no need to talk about harm.

Moderately flammable, low-flammability material is characterized by low smoke-generating ability. Look at the photo with a charred but not burnt room. There was a fire on the top floor, but sprayed polyurethane foam contained the fire due to its low thermal conductivity and non-flammability. Not only hard compounds have such properties, but also high-quality soft ones. Sofas and pillows based on elastic polyurethane foam do not burn, do not emit harmful substances, do not cause allergies, and doctors do not prohibit their use. Cheap brands of foam rubber do not differ in such properties.

Beneficial features

Like any other material, foam has its advantages and disadvantages.

Advantages:

• • Lightness. Used in attics, roofs, light buildings. Doesn't make the structure heavy.
• • Does not require fastening elements or additional parts.
• • There are no “cold bridges”. Seamless thermal insulation.
• • Quick to apply. There is no need to prepare additionally or spend hours near the construction site.
• • You can work with the material at temperatures from -200 to +200 degrees.
• • Withstands changes in temperature and humidity, resistant to frost and heat.
• • Does not react to most alkalis, acids and salts.
• • Excellent surface grip.

In liquid form it is suitable for filling voids. Fills spaces between walls without dismantling ceilings - it simply pours into the hole.

Minuses

Let's talk about what polyurethane foam looks like. It is a hardened foam with or without small pores, depending on the type of mixing. But it also has disadvantages:

• • Does not withstand constant exposure to ultraviolet radiation. It is necessary to protect from direct sunlight. The covering should be attached on top.
• • Apply only to dry and warm surfaces. Before application, the wall or floor should be cleaned of debris and rust to enhance adhesion.

Does not burn, but can smolder when exposed to high temperatures. Thermal insulation will deteriorate, so it is not recommended to use it in baths, saunas and stoves.

Video

What is polyurethane foam?

How to choose a mattress? All about foams (or polyurethane foam, or foam rubber). Consults with GASH master.

Filled polyurethane foam Pouring material into a wall cavity

PPU material: what is it for health?

When the foam has hardened and is in the wall, it does no harm. But during the production process, all safety requirements must be observed. You cannot mix components without:

• •masks;
• • respirator;
• • protective suit.

Helpful Tips:

• • reagents must be tested and certified;
• • place – not blown;
• • equipment – ​​high quality.

If all conditions are met, the foam will be safe.

Liquid insulation for walls: main characteristics

Polyurethane insulation is applied to the walls by spraying using special equipment. Therefore, most often such work is entrusted to specialists, but every homeowner can cope with this task independently, but subject to mandatory compliance with safety precautions and the use of special equipment and personal protective equipment.

In addition to spraying, which is performed mainly on vertical surfaces, the pouring method is sometimes used, but in this case only horizontal planes can be processed, and insulation can also be made by pouring it into pre-prepared molds.

Polyurethane is especially indispensable for insulating various voids, the insulation of which is practically impossible using traditional materials.

For example, often when installing window structures and doors, foam is used to insulate walls in cylinders , the application of which allows you to ideally seal the opening and protect the room from cold and noise.

How to install

One of the most common methods is spraying. Using this method, the material holds well and is used economically; it is suitable for structures with complex geometry, protrusions and recesses. For the process to be successful, you need to:

• • Make sure that the wall or other surface is dry.
• • No high humidity, rain, hail or snow.
• • The wind does not exceed weak 5 m/s, and it is better to protect the work area from it.
• • Make sure that the coating area is warm - not lower than +10 degrees.
• • Heat the mixture - about +18-25 degrees at the time of application; cold is difficult to work with and does not hold well.
• • Apply a layer of no more than 3-5 cm, if thicker is required - in 2-3 steps after drying.

The room must be ventilated. The person should wear a special suit, mask and respirator. Start with difficult areas: pipes, convex or concave parts, ventilation hatches or electrical distribution boxes.

Helpful Tips:

• • It is recommended to apply the composition in several layers. This way the effect will be more significant and adhesion will be higher. It is important to ensure that the previous layer is completely dry. Especially significant on walls with signs of destruction. Here it will lie unevenly and will require 2-3 additional sprayings to even out the area.
• • Before purchasing, you should consult with a specialist to choose the right brand of polyurethane foam with the required impermeability. This will save money and time spent on repairs. You can purchase high-quality, high-strength material.
• • If you apply polyurethane foam taking into account all the requirements and advice, then a coating will appear on the surface that will last for many years and will perform its tasks until the end of its service.

This material is used to insulate the foundation and external walls if necessary. It is also used to treat main pipes to retain heat in them. Mounted on balconies and loggias, used inside toys and sponges for washing dishes. This is a large part of production, which is involved in various fields. It’s easy to purchase, and it’s easy to apply. The result is of high quality and retains its beneficial properties for many years if handled correctly.

Manufacturers

Polyurethane foam insulation has become popular recently. Therefore, new manufacturers of these products are appearing on the market, as well as contractor companies providing installation services.

Reputable PU foam suppliers produce components under their own brands. The rest, as a rule, are resellers, purchasing components from well-known brands. Some firms use local oil refineries.

Using consumer reviews, we can identify several reliable polyurethane foam manufacturers:

Basf

A German chemical concern with branches in 160 countries. The brand produces a wide range of products.

More than 7 thousand items, 60% of which are sold on the European market, about 22% of sales are in the United States of America, the rest is distributed between the markets of South America, Asia, Africa and the Pacific.

In Russia, the company has several subsidiaries, including BASF Construction Systems LLC, BASF Vostok LLC, Wintershall Russland. One of the well-known joint ventures producing polyurethane foam products is.

The company produces polyurethane systems that are available to consumers of any level and for various applications.

Synthesia International SLU

Spanish chemical company founded in 1964. The main direction since 1966 is the production of polyesters, as well as polyurethane systems for various industrial sectors, for example, thermal and acoustic.

Since 1970, polyurethane foam for sandwich panels, construction and refrigeration systems first appeared in the product range. Today the company produces products for different market segments.

The most famous distributor of products in Russia is Global Therm LLC.

This company provides direct deliveries, carries a certain supply of products in a warehouse in Moscow, guarantees a flexible payment system and consultations with technical specialists.

Sipur (Poland)

One of the largest manufacturers of sprayed polyurethane foam insulation.

Thermal insulation products are characterized by low thermal conductivity, which allows the insulation to be applied in a thinner layer (spray thickness up to 6 cm). The company guarantees a service life of polyurethane foam of about 50 years.