How to self-spray polyurethane foam?

If necessary, the insulation of various premises from the basement to the attic an excellent solution would be polyurethane foam. Material with outstanding properties obtained by mixing polymeric substances, perfectly fits on all types of surfaces. With it, even alone, you can make high-quality insulation in homes for a reasonable price.

The synthetic nature of the polymer allows you to modify its properties, improving them to indicators inaccessible to natural materials. In particular, polyurethane foam is an excellent insulator and has excellent adhesive properties.to almost all types of surfaces encountered in the arrangement of thermal insulation.

Strong grip is provided with materials such as:

• wood - 1.5 kg / cm²;
• galvanized and cast iron - 2.0 kg / cm²;
• aluminum - 1.0 kg / cm²;
• stainless steel - 1.5 kg / cm ²;
• cement - 2.5 kg / cm²;
• steel - 3 kg / cm ².

In addition, the positive features of the material include the following:

• low thermal conductivity - 0,019–0,028 W / m²;
• lightness, not affecting the weight of structures - from 40 to 60 kg / m³;
• does not need fasteners - cost savings;
• protects the coated metal from corrosive processes;

• there are no cold bridges;
• the ability to cover surfaces with any geometry;
• high durability, the material does not rot, does not dry out, does not collapse under the influence of atmospheric phenomena, temperature drops and other environmental phenomena, except for ultraviolet radiation;
• absolute safety, polyurethane foam is inert chemically and biologically, approved for use in refrigerators for food;

• using a form with the required dimensions, you can create heat-insulating blocks of any format;
• the material is not interesting as food for rodents and insects, fungus and other microorganisms do not breed on it, and it also prevents the growth of plant roots;
• resistant to aggressive substances: solvent, softener, fuel, mineral oil, dilute acid and alkali, chadny gases of various origin;
• refers to slow-burning substances, burns from the side of contact with direct fire, and only if there is one, when it disappears, it goes out, the burned-over layer turns into coal and no longer supports combustion.

In addition to positive qualities, PPU has its drawbacks, among which the following should be highlighted:

• the finished layer of polyurethane foam is vulnerable to sunlight (ultraviolet). To compensate for this disadvantage, PU foam is coated with paint or film with the necessary protective properties;
• although PUF is not combustible, it should not be used near a source of fire, for example, a fireplace or a gas stove, even if it does not catch fire, it can smolder or melt;
• relatively high cost.

Polyurethane foam is a material related to gas-filled plastic with a cellular structure filled with air.

After 2–4 seconds after mixing the components, the polymer foams out, and when applied to the surface, a homogeneous mass with high thermal insulation properties is formed. Foaming is accompanied by an increase in temperature and an increase in viscosity, after which the material hardens.

PUF is divided into two main types, such as:

• open-mesh or soft polyurethane foam, which is used in light industry;
• closed cell or rigid PUF, which is used in thermal insulation.

Solid polyurethane foam with a closed cell structure is formed by the combination of two components.

• Polyol (A) - It is a hydroxyl substance, protruding polymer base PUF. It is weakly toxic and non-explosive, must be saved at a temperature of 0 ° C and higher in a room with low humidity and good ventilation. Due to the tendency to exfoliation, component “A” must be mixed before use.
• Isocyanate (B) Is a mixture based on diphenylmethane diisocyanate (from 50 to 60%) and polyisocyanate. It has a high activity when it comes into contact with air, as a result an unsuitable deposit is formed, which necessitates hermetic storage.

From a technical point of view, PPU has the following characteristics:

• Density is 18–300 kg / m³;
• Thermal conductivity - from 0.019 to 0.03 W / m²;
• breaking stress in compression - from 0.15 to 1 MPa, bending - from 0.35 to 1.9 MPa;
• moisture absorption - from 1.2 to 2.1%;
• the number of closed pores is from 85 to 95%;
• combustibility in accordance with GOST 12.1.044 (slow-burning substances).

The quality of the components and the correct proportion are the most important conditions for obtaining good polyurethane foam. In small stores, polyurethane foam cylinders are often sold with incomprehensible markings, the result of which is the loss of money and the receipt of extremely unsatisfactory insulation. That is why it is recommended to select proven manufacturers whose products have only positive feedback from buyers.

• Yantai Wanhua - It is a large Chinese company manufacturing PPU. She is one of the world leaders in the sale of polyurethane foam. Products are certified in accordance with all quality standards and at the same time have a reasonable price. By purchasing such a product, you can be sure of a guaranteed exchange in the presence of factory marriage.Product Names: Component A - Wanfoam-323C-1, Component B - Wannate PM-200.
• Bayer - It is a large German chemical and pharmaceutical concern of world renown and an excellent reputation. Trade names of PPU components: component A - Bayer Spray 150, component B - Desmodur 44V20 L.

• BASF - This is a German chemical company with more than 150 years of experience, it is considered the world leader in the production of high quality PU foam components. The resulting insulation is characterized by a uniform structure, the components are mixed without any side complications. Product Names: Component A - Elastospray 1652 / 1-3, Component B - IsoPMDI 92140.

When calculating the consumption of polyurethane foam components, several factors are paramount.

• The thickness of the applied layer. Directly determined by the required level of insulation and depends on the density of a particular PUF.
• The area to be treated (S). It is calculated using the standard form S = l * h, where l is the length of the surface, and h is its height. The volume of the required PUF (V) is calculated from the formula V = S / p, where p is the consumption per 1 m².
• Applicable blowing agent and type of work: pouring or spraying. It is standardly considered that the consumption of component A and B is 1: 1.In practice, using the Freon system for spraying consumes 1: 1, for pouring - 1: 1.1. When using an aqueous system for spraying, 1: 1 is also consumed, and 1: 1.5 for casting.

There is a simple option to do spraying with your own hands. To do this, you must buy one of the disposable sets. FoamKit from the American manufacturer is an excellent choice. With it, you can single-handedly insulate a private house, cottage, attic of a cottage or other room. The disposable set consists of two small cylinders, to which a hose and a special pistol with different nozzles are attached.

In general, the spraying process is as follows:

• you need to be located at such a distance that from the gun to the wall was about 80 cm;
• the first non-thick sprayed layer is applied to ensure better adhesion with the wall;
• after 20 minutes, when it dries, the next layer is applied, which should not exceed 2.5 cm in thickness, and so on until the required thickness, with stops for drying the fresh layer;
• in the final layer, excess and sagging are leveled off 2–5 minutes after application. Self-made spraying done.

During the work it is necessary to observe a number of the following conditions:

• the surface must be dry and free from dust and dirt;
• the temperature should not be lower than + 5ºС, while depending on the humidity the temperature of the working surface should exceed the dew point temperature by 3 degrees.

The use of disposable sets with sprayers is financially justified when working in areas not exceeding 30 square meters. m. And there are also many subtleties, by definition, of proportions for the desired result, non-specific surface and other nuances that need to be taken into account even in the presence of factory components and equipment.

In addition to cylinders with components, such items as hoses, a gun, and nozzles are included in the disposable set. Professional equipment consists of many parts and is often a mobile unit like a gas welding machine.

High pressure sprayers include the following:

• "Foam-20" - This is a product of a Russian company that can mix components in 11 different variations. The device is equipped with two 2.5 meter hoses extended to 60 meters if necessary. It allows you to produce 1-3 kg of PPU per minute, mixed in proportions from 1: 0.93 to 1: 1.7. Dimensions are 115x55x90 cm, and weight - 110 kg.
• Reactor E-10 - This is an American installation for spraying polyurethane foam, polyurea, polyurethane, epoxides and others. It has a compact size of 52x55x95 cm and a relatively small weight of 72 kg. It produces up to 5.4 kg of mix per minute, the length of the hoses is up to 32 m.

In carrying out work on the application of polyurethane foam, it is necessary to adhere to a number of prescriptions. With their help, it is possible to improve the quality of the surface, reduce the consumption of components, eliminate the need for re-application due to peeling and other things.

Spray material on the roof is not difficult if you follow the following recommendations of experts:

• sprayed material must be used with extreme caution;
• The surface on which the foam is applied must be thoroughly cleaned and have a uniform structure.From it should be removed dirt and dust, small debris, traces of oils and fats, easily falling off pieces of the surface;
• when working with a porous type of material, it is better to prime it before processing the PUF to enhance adhesion;
• the humidity of the working surface should correspond to such indicators, respectively, the base material, such as: concrete - 4% or less, cement-sand - 5% or less, wood - 12% or less;

• before applying the wet surface should be blown with compressed air, and at a temperature of less than + 10ºС - with warm compressed air;
• when mixing the components, their temperature and temperature of the hoses should not be below + 20ºС. If necessary, they must be placed in a room with a higher temperature for heating;
• Component A should be thoroughly agitated before mixing, this can be achieved by rolling the container or switching on recirculation when using a high-pressure spraying apparatus;

• the finished layer of polyurethane foam is vulnerable to ultraviolet, after applying it is better to coat it with paint or film with the necessary protective properties;
• strong wind significantly affects the spray pattern and work in such weather is not recommended due to overruns of components;
• if in component B crystals have formed, it is recommended to heat it to a temperature of 65 ° C using a thermal belt, a heat gun, or a similar method. Heating stops after complete dissolution of the hardened parts. Before mixing, the component must be cooled to operating temperature.

To learn how to self-spray polyurethane foam, see the following video.