Technical polyurethane foam. Polyurethane foam - properties and selection criteria. Rules for using polyurethane foam

Polyurethane foam has excellent insulating properties and has a fairly wide range of applications. We will help you understand its types, talk about the rules of use and tell you which polyurethane foam to choose. We’ll also talk about how to wash foam from the surface.

Types of polyurethane foam and main characteristics

The appearance of polyurethane foam on the building materials market at one time became a real revolution in this area. And all because it has such properties as:

high moisture resistance, heat and sound insulation;
low conductivity of electricity;
fire resistance;
the ability to fill various voids, thereby ensuring high quality seams and joints;
environmental friendliness;
ease of use;
the ability to glue different materials together, etc.

Thanks to these characteristics, many builders can no longer imagine their work without this sealant. It is used to install various structures (windows, doors), seal construction seams, gaps and cracks in the surface, provide heat and sound insulation in rooms, etc.

Household and professional

Depending on the method of application, household and professional foam are distinguished. Professional foam is used only in conjunction with a special gun for polyurethane foam, which helps to dose it more accurately, increase yield and extend its service life. Such foam predictably increases in volume, has a small percentage of shrinkage and is suitable for performing a large volume of work, for example, installing windows, doors, etc.

Household foam does not require a gun, as it has a special adapter tube with a lever through which the foam is supplied. It is intended for single use. Therefore, most often it is purchased for minor work, for example, sealing cracks or cracks. Household sealant has a lower filling density of the cylinder compared to professional sealant. The foam yield is average, and it may not come out completely. Such foam approximately doubles in volume, and shrinkage is 5-7%.

Winter and summer

Polyurethane foam, which is commercially available today, can be roughly divided into three types depending on its operating temperature:

summer foam is used if the temperature of the treated surface is from +5 to +35 degrees Celsius;
winter foam allows installation work to be carried out in the cold season at temperatures from -18 to +30 degrees Celsius;
all-season has all the positive properties of the two previous types. It can be used at air temperatures from -100 to +350 degrees Celsius.

Single-component and multi-component

Single-component and multi-component foam is also available. The difference lies in the technology of its production. The first one is the most common. It is a ready-made mixture of various elements, which is sold in aerosol packaging. Part of the chemical reaction occurs already inside such packaging. The second, multi-component, goes on sale in a special container, divided inside into two parts. One of them contains the components of the substance, and the second contains various additives - foaming agents, catalysts, etc., which are mixed together only before use. To do this, the container must be shaken well. Since the chemical reaction in the second case occurs much later, the service life of such a sealant is much longer.

Selection tips regarding applications and ambient temperatures

When choosing polyurethane foam, the conditions in which it will be used play an important role. In particular, it is worth considering the temperature and humidity of the air. The process of polymerization or hardening of the sealant depends on these indicators. The higher the temperature, the faster the surface hardening of the foam occurs and, accordingly, the slower the volumetric hardening. As the temperature decreases, the viscosity of the product increases, causing the foam to come out worse and the container not to be completely emptied.

Experts note that the ideal conditions for working with conventional polyurethane foam are an ambient temperature of 18-25 degrees Celsius and a humidity of 60 to 80%. Therefore, before using the cylinder, it is recommended to keep it at room temperature for 24 hours and under no circumstances try to heat it in a water bath. This may lead to rupture of the cylinder or deterioration of the properties of the material. Do not forget that there is a special frost-resistant sealant that can be used in the winter season. But in any case, when working with winter polyurethane foam, the temperature of the cylinder itself should not be below 0 degrees, and preferably not below 10 degrees.

The main stages of working with polyurethane foam

Polyurethane foam is a universal material that is quite easy to work with. The process itself consists of the following stages:

Before starting work, the aerosol can with polyurethane foam must be shaken well for one minute. Thus, its contents will have a uniform consistency and will be evenly distributed.
The surface to be treated must be moistened with water. This will help improve adhesion to the material.
When applying foam, the household container must be held upside down. Then the stream of foam will be continuous. Vertical seams are sealed from bottom to top. The first layer of foam should be no more than 3 cm, each subsequent layer is applied only after the previous one has completely hardened. Do not forget about moistening the working surface.
After hardening, the foam can be processed, for example, cut off in those places where it interferes, cover the place where it is applied with platbands, putty or plaster the surface, cover it with paint, etc.

There are certain rules for working with sealant that will help achieve good results:

During the polymerization of the foam, touching it with your hands is prohibited.
It is better to work with gloves, as the sealant is difficult to wash off.
If foam gets on other surfaces, it must be removed immediately using a cloth soaked in solvent.
Dried foam is destroyed by sunlight, so it must be treated: plastered, painted or covered.

Rules for using a mounting gun

When working, it is very important to be able to use the mounting gun correctly. This will help you cope with the task quickly and without any problems, and will also extend the life of the device itself.

A mounting gun is a device through which foam is supplied under pressure to the surface to be treated. The first thing the master must face is installing the gun in the working position. To do this, you need to take the bottle in your hands and shake it thoroughly for 30 seconds. Then remove the protective cap and, turning the neck down, screw the cylinder into the thread of the gun. After checking the correct installation of the gun by testing the foam to the side, you can proceed to the actual work of foaming cracks and voids.

If during operation the foam in the cylinder unexpectedly runs out and it is necessary to screw on a new cylinder, then first turn the gun over with the handle up and unscrew the empty cylinder. Then, using washing liquid, clean the attachment point and only then screw on a new cylinder.

If the work on sealing the seams is completed, but the foam remains in the cylinder, it is imperative to tighten the adjusting screw to the very end so that the foam stops flowing into the barrel. After this, you need to clean the outlet from any remaining substance with a solvent, but do not unscrew the gun from the cylinder. This way the foam is guaranteed not to dry out during storage and can be used another time.

In order to clean the mounting gun from foam residues, use a special washing liquid. It is sold in the same container as the foam. It is screwed onto the barrel of the pistol and the barrel is filled by pressing the trigger. The device is left in this state for 10-15 minutes, after which the remaining foam and cleaning agent are released and the operation is repeated again.

How to wash polyurethane foam and remove its traces

After completion of the work, as a rule, it is necessary to remove traces of polyurethane foam. The main condition is a fresh stain. Dried foam is much more difficult to wipe off. First, a mechanical method is used. In places where this is possible, the foam is cut off with a knife or removed with a rag or napkin, being careful not to smear the foam over the surface. Where this cannot be done, a solvent is used (rinsing for the mounting gun, acetone, gasoline, solvent 646, etc.). First, a small amount of the substance is applied on top of the dried foam. When it softens, remove it with a damp cloth. If there are still traces left, the procedure is repeated. Do not forget that the use of a solvent increases the risk of damage to the surface being cleaned, so you need to be very careful. Test the effect of the solvent on the material in an inconspicuous area.

Advice! Experts recommend Dimexide. This medicine is sold at the pharmacy, is inexpensive and will help you wash the foam from the surface.

EuroProfile→Product Catalog→ Foams and sealants

Professional polyurethane foam Makroflex Winter Pro (winter) is a one-component polyurethane mixture, produced in metal pressure cylinders with a volume of 0.75 and 1.0 liters. One 0.75 liter cylinder yields up to 25-50 liters of foam (“usable yield” depends on external conditions: humidity, volume of voids to be filled, air temperature, etc.). Polyurethane foam in the open air begins to expand and harden under the influence of atmospheric moisture. The expansion coefficient of foam is 2.0-2.5. The lower the ambient temperature, the lower the degree of expansion.

Each cylinder is equipped with a special valve for the ability to work with an applicator gun. Polyurethane foam is widely used for sealing large cracks and gaps, and is also used as an additional installation material.

Polyurethane foam is used

— when installing window and door frames;
— for sealing various holes, cracks, joints with large gaps;
— when installing roofs (foam fills the voids between the supporting structure of the roof and insulating materials);
— to create heat or sound insulating screens;
— for the purpose of sealing gaps in ceilings when laying pipelines.

Properties of winter polyurethane foam Macroflex

— excellent adhesive characteristics, the foam has good adhesion to almost all building materials: stone, wood, concrete, brick, cellular concrete, plasterboard, gypsum fiber, etc.;
— unique noise and heat insulation characteristics;
— high resistance to moisture;
— when expanding, the foam fills all possible voids as much as possible;
— economical consumption (provided by dosed supply to a strictly defined location);
— high durability;
— after hardening, Makroflex Winter Pro foam is not toxic or flammable.

When using polyurethane foam, you should remember the need to protect it from direct sunlight (it is destroyed by ultraviolet radiation). In order to protect the polyurethane foam from ultraviolet radiation, it is enough to paint its outer surfaces with regular enamel.

Storage conditions

Cylinders with polyurethane foam are under pressure, so they should not be stored at ambient temperatures of +50°C or higher, or near heat sources or open flames.
During long-term storage, the ambient temperature range should be within -5…+25°C. Short-term storage is allowed at a temperature of -20°C.

Rules of application

Makroflex Winter Pro polyurethane foam should be used at an ambient temperature of at least -10°C. Before installation work, foam cylinders should be kept at room temperature for 12 hours.

Before directly applying the foam, the can should be shaken well for 15 seconds. After this, the balloon can be placed in the applicator gun or a tube can be screwed to it (it comes complete with the balloon and is used in the absence of an applicator).

When working, the container with polyurethane foam must always be kept upside down. The foam is applied to clean, dust-free surfaces. For better adhesion, surfaces can be moistened. The presence of ice or frost is not allowed. When working with foam, approximately half the volume of the compacted space should be filled (taking into account its expansion coefficient).

The used cylinder is replaced with a new one before the mounting foam begins to harden in the guide tube. If installing a new cylinder is not necessary, then the remaining foam should be removed from the gun with a special cleaning agent (we recommend Makroflex Cleaner).

After the foam at the installation site has expanded and completely hardened, its protruding remains can be cut off with a stationery knife. The cut areas can be plastered, puttied, covered with plasterboard or other finishing material.

When working with Makroflex Winter Pro polyurethane foam, it is necessary to use personal protective equipment, since the foam adheres well when it comes into contact with exposed skin.

Polyurethane foam Macroflex technical characteristics and consumption

The already familiar solutions and fillers have been replaced by Makroflex polyurethane foam. Its use facilitates the installation of building structures and repairs inside and outside buildings and premises.

Technical characteristics of Macroflex foam 750 ml

The manufacturer presents several types of these products, differing in technical characteristics, external design and container volume. The technical characteristics of Macroflex foam 750 ml directly depend on its type.

All about polyurethane foam

There are the following variations: Standard, Professional, 2x2, Standard winter, Professional winter, Macroflex 65, Premium, Premium MEGA, Premium WINDOW, FR77. Standard variations differ from professional foams in that they come in a bottle. Standard foams come with a disposable plastic tube for directed release of contents. Professional bottles have a valve for installation in an applicator gun. The foam composition is one-component, which prevents delamination and destruction of the hardened material - polyurethane. The cured material is soundproof, heat-insulating and moisture-resistant. In addition, it is not destroyed under the influence of atmospheric and chemical influences, but is removed only mechanically. UV radiation negatively affects the quality of building materials. Therefore, it must be used extremely carefully in compliance with all safety measures, and if necessary, its uncured residues are removed with a special solution.
The Premium WINDOW and FR77 subspecies are multi-seasonal. The latter is fire resistant. Standard Winter, Professional Winter, 65 and Premium are winter options and their curing time depends on the ambient temperature. At the same time, winter ones can be used in the summer months, and summer types only at temperatures not lower than +5. The rate of hardening of summer foams depends on air humidity; the higher it is, the faster the material hardens. Each foam has its own compressive and tensile strength and ranges from 3x to 5N/cm2. They have excellent adhesive properties to all common materials, including wood, metal, stone, concrete slabs and plastic.

Makroflex foam consumption

One 0.75l bottle, depending on the type of contents, yields from 20 to 65l. The output volume depends not only on the quality characteristics of the content, but also on the conditions and installation technique. Reduced humidity does not allow the foam to expand significantly, and incorrect positioning of the bottle reduces its throughput.

Also, the consumption of Makroflex foam depends on the target needs and functional purpose. The amount consumed depends on the area of application and the number of layers. According to the manufacturer, the output volume of Makroflex polyurethane foam is 10% higher than that of competing companies.

Video what polyurethane foam is and its features

The popularity of polyurethane foam consists of its affordable cost, ease of use, excellent adhesion, widespread availability and cost-effectiveness. You can buy sealant at any specialized retail outlet, and a large range of materials allows you to make the right choice. In addition to the usual ones, manufacturers produce fire-resistant and frost-resistant compounds, indicating on the cylinders the average consumption of polyurethane foam. But these data relate to work performed under ideal conditions, and therefore quite often diverge from reality.

Regulatory requirements

The Internet has provided a real opportunity to perform calculations on the consumption of polyurethane foam online. Calculators can be found on various sites, but they are available only to confident users of the World Wide Web. Home craftsmen can also use the manufacturers' instructions indicated on the packaging, or regulated standards, if available. But in both cases, it is recommended to increase the obtained result in order to prevent the situation of emptying the cylinder at the most inopportune moment.

Please note that different polyurethane foams have different consumption per square or linear meter.

Sealant consumption depends on a number of factors:

high-quality composition of polyurethane foam;
the required depth of filled cracks, joints, junctions and other recesses;
use a plastic tube or special gun when applying;
presence of a dispenser;
professionalism of the master;
uniformity of mass distribution;
percentage increase in volume;
temperature and humidity conditions accompanying the working process.

The consumption of polyurethane foam in the standards used by estimators is calculated based on the performance of work in optimal conditions, using a professional mounting gun. At the same time, attention is paid to the mandatory moistening of surfaces before applying the sealant, periodic shaking of the container, and uniform distribution of the mass in the bottom-to-top direction.

Calculation of the required amount of foam per square meter when installing window blocks is made taking into account the thickness of the seam of 35-40 mm and its location along the entire perimeter of the opening. For example, if the window has an area of up to 3 square meters, then the consumption of mounting sealant will be 1.24 cylinders with a capacity of 0.75 liters. If the opening is more than 3 square meters, then 0.7 of a cylinder of the same volume will be consumed per square meter.

In the case of laying thermally efficient blocks, about ten liters of foam will be needed per square meter. But this standard indicator is not final. Any construction company has the right to change the figure upward, justifying the amendment by the circumstances that have arisen. Individual standards are approved in accordance with the procedure established at the enterprise.

In the accepted state prices, there is another indicator of foam consumption - per 100 linear meters of seam. An example would be the renovation of balconies. In this case, four bottles of sealant with a capacity of 0.85 liters will be required. Many professionals proceed from a different, fairly simple formula.

Facts about polyurethane foam

For four linear meters of a typical size gap, they “take” a liter of expanding volume of polyurethane foam. As a rule, this number is present on the cylinder. In other words, approximately the following correspondence is written on it - 900ml = 65l.

Additional terms

The width and depth of the mounting joint has a huge impact on the consumption of polyurethane foam. Approximate calculations for different indicators can give significant differences in numbers. For example, if the difference in seam width is 3.5 times, and in length - 2.5 times, the sealant consumption may increase (or decrease) by 8 times. But only if no additional materials are used to fill the joint.

None of the documentation or instructions for use provide accurate data on the consumption of polyurethane foam. All figures are averaged and adjusted to optimal conditions. But they make it possible to find out at least the approximate number of cylinders required to carry out work on sealing joints. An individual approach to calculations helps construction organizations include figures that are closest to specific conditions in their estimates, and helps home craftsmen estimate possible costs.

Low-, medium-, and high-expanding foam-based sealants can produce significant variations in fill volume.

Some of them tend to expand only two to three times during polymerization, others expand almost six times. A can of one manufacturer may be enough to seal an entire window, while the same volume of packaging from another company’s products will not fill even half of the identical joints. As a result, we can conclude that calculations of foam consumption are made only relatively.

03/14/2017 at 00:03

How much polyurethane foam is needed for one window?

Both the installers themselves and ordinary citizens need to know the consumption of polyurethane foam. The first is for drawing up estimates when performing work on an order (often a government order).

The second is for the purchase of a certain amount of material, to control the honesty of hired workers. In any case, I would like to know what the consumption of polyurethane foam is for a window, a door, or for installing all the windows or doors in the apartment.

Regulations

Any professional installer will tell you right away how many foam cylinders you need to buy to install all room doors, for example.

How much foam is in the can? Experiment with polyurethane foam

But at the state level, rules have been developed for determining construction work, building mixtures and materials. The consumption rate of polyurethane foam can be calculated using the GESN tables (State elemental estimate standards).

What to consider when calculating the consumption of polyurethane foam?

1. Areas of processed building structures.

If you need to install a window, for example, then take the area of the window opening. It is calculated by the outer dimensions of the box.

2. Material of the building structure (stone, wood, panel part, PVC, etc.).

3. Thickness of the building structure.

What do the GESN tables say?

Treatment of empty cavities with polyurethane foam when installing PVC window sill boards

To obtain the data, we took into account a standard 750 ml cylinder of polyurethane foam, and one hundred linear meters as a meter.

Filling with foam the cavities between the door frames and

walls of the building

To obtain the data, we took into account a standard 750 ml container of polyurethane foam and a meter of one hundred meters of square openings.

These are averages. In practice, the numbers may be slightly different.

What determines the consumption of polyurethane foam?

1. From the brand of the foam itself.

More precisely, from such a technical parameter as “primary expansion”. One foam needs to fill a third of the gap volume, the other – half.

There are highly expanding, moderately expanding and weakly expanding foams. All household options are highly expanding. They have to fill quite large gaps. Therefore, they cannot damage the building structure. In addition, spacers are installed that maintain the position of the structure.

Medium-expanding and low-expanding foams are needed for more delicate work, “clogging” small cracks.

2. From the ambient temperature.

This is relevant if external installation work is being carried out. The colder it is, the more foam you will have to spend. This is why winter specimens disappear too quickly. After all, air humidity at sub-zero temperatures is low, so the foam increases in volume less.

Based on materials from the site: http://stroy-king.ru

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Calculator for converting liters of polyurethane foam to kilograms (kg)

How many kilograms are in a liter of polyurethane foam?

Theory:

Mass is a characteristic of a body, which is a measure of gravitational interaction with other bodies.

Volume is a quantitative characteristic of the space occupied by a body, structure or substance.

Density is a physical quantity defined as the ratio of body mass to body volume.

The relationship between liters and kilograms of polyurethane foam is determined by a simple mathematical formula:

V = m/p, where

V—volume;
m—mass;
p—density.

In the calculation, the density of the polyurethane foam was taken = 30 kg/m3.

The density of polyurethane foam can vary depending on temperature and pressure. You can find the exact density of polyurethane foam in reference books.

See also the universal program for converting liters to kg for any substance depending on its density.

If you need to convert m3 to tons, then see the program for converting tons to m3.

If you need to convert kg to m3, then see the program for converting kg to m3.

Question answer:

Question: How many kg are in a liter of polyurethane foam?

Answer: 1 kg of polyurethane foam is equal to 33.3 liters.

Question: How many liters are in a kilogram of polyurethane foam?

Answer: 1 liter of polyurethane foam is equal to 0.03 kilograms (kg).

Solutions:

You can quickly solve this simple mathematical operation using our online program. To do this, enter the initial value in the appropriate field and click the button.

This page presents the simplest program for converting kilograms of polyurethane foam into liters. Using this online calculator, you can convert liters of polyurethane foam to kg and back in one click.

The history of the appearance of polyurethane foam

Polyurethane foam in the form in which it is known now began to be widely used in the 80s of the last century. But polyurethane foam, one of the types of which is polyurethane foam, was invented much earlier, back in the 40s, by the Swiss Otto Bayer, who headed a laboratory at the Bayer chemical concern. By the way, Otto himself has no relation to Friedrich Bayer, one of the founders of the concern, he is simply a namesake.

One-component, one-and-a-half and two-component polyurethane foam

Polyurethane foam can be one-component or two-component. In one-component foam, a pre-mixed prepolymer and a propellant gas, also called propellant, are placed in a canister. When leaving the container, the prepolymer foams, begins to interact with the moisture contained in the air, and polymerizes. If there is a lack of moisture, polymerization will be difficult, and large voids may remain inside the foam mass.

One-and-a-half-component foam, often called two-component foam, is stored in a container consisting of two parts. In one part there is a prepolymer, almost the same as in one-component foam, and in the other there is a catalyst that accelerates the curing process. Products from different parts of the cylinder are mixed immediately before use. One-and-a-half-component foam has a higher density than one-component foam, lower secondary expansion and lower yield. But it hardens very quickly. This type of foam is used for quick fixation of window and door blocks in openings instead of mechanical fastening. One-and-a-half-component foam is used quite rarely, since it is more expensive, has a smaller output volume and must be applied within 15 minutes after activation, otherwise it will harden in the container. In the vast majority of cases, the use of one-component foam is more economically feasible.

Two-component foam is obtained directly during application by mixing two different components using special equipment. This technology is used to produce a lot of products: from mattresses and car seats to thermal insulation, shoe soles and wood substitutes.

Application area of polyurethane foam

Due to such properties of polyurethane foam as low air permeability, low thermal conductivity, ease of use, it has found its application for sealing gaps when installing windows and doors, sealing cracks, insulating openings for pipes and cables, insulating balconies and other building structures. Today, more than 2,000 areas of application of polyurethane foam are known, ranging from construction to art. It must be clearly understood that ordinary polyurethane foam is not recommended for waterproofing, since it absorbs moisture. In some cases, only special types of polyurethane foam can be used for waterproofing. In addition, polyurethane foam is destroyed by ultraviolet radiation, and therefore requires protection from sunlight.

The excellent adhesion of polyurethane foam to most surfaces has also found application in construction. Special products have appeared, such as adhesive foam based on polyurethane foam. They differ from conventional polyurethane foam in that they have relatively low primary and secondary expansion, but at the same time higher adhesive properties. Using these products, thermal insulation boards are glued to walls and used as a binder for building blocks, wood materials, plasterboard, and metal tiles.

Polyurethane foam output volume

Perhaps the first characteristic that end consumers pay attention to. This is really important: the more foam that comes out of the can, the more work you can do with it. And this is a direct saving of both time and money. What determines the volume of foam yield?

First of all, it depends on the amount of active substance filled into the container. The weight of the cylinder can serve as a criterion for this. You can often find that identical-looking cylinders from different manufacturers with the same declared volume of foam output differ greatly in weight. All other things being equal, more foam should come out of a heavier container than from a lighter one.

However, the volume of output depends not only on the filling of the balloon. Finished foam from different manufacturers may have different characteristics, such as density. And it is not always possible to obtain a larger output volume from a heavier cylinder than from a lighter one. In the same way, the foam that gives more volume is not always the best in other characteristics. For example, it may have a lower density and, as a result, worse thermal insulation.

Often people who decide to independently check whether the volume of foam output corresponds to that declared by the manufacturer discover that the volume turned out to be less than expected, and rush to accuse the manufacturer of dishonesty. But often the reason lies not in the buyer’s body kit, but in the test conditions. The volume of foam output is indicated for normal conditions, which are considered to be a temperature of +23°C and a humidity of 50%. The maximum volume of foam yield can be obtained only in laboratory conditions, fully observing the testing technology used by the manufacturer. For example, in dry weather or frost, the volume of foam output may be one and a half or even two times less. As for comparisons of the output volume from different cylinders, they can only be correct if the tests of these samples are carried out under the same conditions, by one person from the same gun, and best of all simultaneously.

Primary expansion of polyurethane foam

Primary expansion is the increase in volume of liquid foam immediately after the foam exits the nozzle. The mechanism of this process is as follows. Gases and prepolymer are in a cylinder under a pressure of about six atmospheres. Before use, the container is shaken, the gases are mixed with the prepolymer and partially dissolved in it. When leaving the cylinder, the mixture experiences a sharp drop in pressure and the gas bubbles compressed inside rapidly expand, forming foam. The process is similar to how carbonated drinks froth when opening a sealed bottle. This is why it is important to thoroughly shake the container before use: if this is not done, the output will not be high-quality foam with the stated output volume.

Naturally, the amount of primary expansion very much depends on external conditions: air temperature, application method, worker qualifications.

Secondary expansion of polyurethane foam

Secondary expansion is an increase in foam volume after the end of primary expansion and before complete polymerization. It is indicated as a percentage. Secondary expansion of the foam occurs as a result of the interaction of the prepolymer with moisture. During this reaction, carbon dioxide is released, the structure is formed and the foam hardens. The amount of secondary expansion depends on the formulation used and can vary from 15% to 60% for professional foam and from 200% to 300% for household foam for different manufacturers and different types of foam. Secondary expansion is a very important indicator that directly affects the quality of most work performed with foam. Therefore, before starting to work with foam that is new to you, it is recommended to conduct an experiment to determine the degree of secondary expansion and take this parameter into account when working.

Expansion pressure of polyurethane foam

As the foam expands, it puts pressure on the structure. The strength of this pressure depends not only on the degree of secondary expansion, but also on other characteristics of the foam. Foams with a high degree of secondary expansion do not always exert great pressure on the structure. This can only be established experimentally and, of course, then take this parameter into account when working with a specific brand of foam. When switching to another foam, you need to keep in mind that its expansion pressure may be greater and it may deform the structure more.

Time for initial processing of polyurethane foam

This term refers to the time after which the foam hardens enough so that it can be subjected to mechanical processing: trimming off excess, preparing for painting or putty. Manufacturers indicate this parameter on the cylinder; as a rule, it is several tens of minutes. But it should be borne in mind that this period is indicated for ideal conditions. In reality, it is best to make a test cut before machining to ensure that the foam has hardened sufficiently.

Time for complete polymerization of polyurethane foam

The time of complete polymerization is the time during which all chemicals in the foam are completed and the foam acquires its final structure. The polymerization time depends on several parameters: the quality of the foam itself, the thickness of the seam, the amount of available moisture and temperature. The faster moisture penetrates the foam, the faster and better the polymerization process. That is why it is recommended that before applying the foam, moisten the surfaces on which it will be applied, and after application, moisten the already foamed seam again. However, excessive wetting should be avoided - the surface should be damp, but not wet. With temperature, everything is the same as in any chemical reaction - the warmer it is, the faster the reaction goes. Under normal conditions, the polymerization time of polyurethane foam is about 12 hours, but in frosty or dry weather, polymerization is much slower and can take several days. As for the thickness of the seam, numerous experiments from various manufacturers show that moisture can penetrate into the hardening foam to a depth of no more than 3 cm. To layers lying deeper than 3 cm from the edge, penetration of moisture is difficult, therefore the diameter of the foam roller applied in one pass is should not exceed 6 cm. If it is thicker, there is a big risk that the middle of the roller will not polymerize - a void will form there. Such a seal will have poorer sound and heat insulation and can easily collapse. That is why large openings need to be filled with foam in layers. The second layer can be applied no earlier than a crust has formed on the first. And it is imperative to moisten the surface on which the second layer will be applied.

“Shrinkage” of polyurethane foam

During the polymerization process, the carbon dioxide formed in the foam, which creates excess pressure inside, gradually leaves the pores and is replaced by air. Depending on the speed at which these processes occur, the foam can shrink or expand. In world practice, it is believed that fluctuations in foam sizes of ±10% are acceptable for the installation of plastic windows and doors.

Storage conditions and shelf life of polyurethane foam

Cylinders with polyurethane foam must be stored in a vertical position with the valve facing up at a temperature from +5°C to +25°C. Only under these conditions does the manufacturer guarantee that the foam will retain its qualities throughout the entire shelf life indicated on the packaging. The temperature limits at which the foam must be stored may not be the same as the limits at which it can be applied. So, for example, you can work with winter foam at a cylinder temperature down to -10°C, but if you store it in the cold, it will become unusable much earlier than the period indicated on the cylinder. Freezing of foam is allowed, but after this, to maintain the performance characteristics of the foam, the cylinders must be properly defrosted. They need to be defrosted slowly, avoiding sudden heating.

Conditions for applying polyurethane foam

Different types of polyurethane foam may have different application conditions; they are usually indicated on the container. For summer types of foam, the air temperature usually ranges from +5°C to +35°C; the highest quality winter foams, for example, KUDO ARKTIKA NORD, can be used at air temperatures down to -25°C.

It is necessary to distinguish between the outside air temperature at which the application of polyurethane foam is allowed and the temperature of the cylinder itself. For example, KUDO ARKTIKA winter foam can be used at temperatures from -18°C to +35°C, and the temperature of the cylinder should not be lower than -10°C. This is considered a very good indicator, since KUDO foams use AFC (Advanced Freeze Control) technology, which allows work to be done with a cooled cylinder. For foam that does not have such technologies, the permissible temperature of the cylinder is usually above 0°C. If the cylinder has cooled below the critical temperature, it must be warmed up by placing it in warm water for some time. Under no circumstances should the cylinder be heated with an open flame or a hair dryer - overheating may cause the cylinder to explode. Another important nuance is that there should not be too much of a difference between the temperature of the foam and the temperature of the outside air, otherwise after application the foam may simply leak in the opening. To select the optimal temperature for KUDO foam, you can use a special table.

An equally important condition for proper application of polyurethane foam is sufficient humidity, usually it should be at least 50%. The foam polymerizes when it reacts with moisture, so to obtain a high-quality seam, it is recommended to always moisten the surface on which the foam will be applied before starting work, and after application, moisten the foamed seam again. If the foam is applied in several layers, each layer should be moistened.

Fire-resistant polyurethane foam

Fire-resistant polyurethane foam is used in places with increased fire safety requirements. As a rule, fire-resistant foam is pink or red in color, occasionally gray. Thanks to this, it is easy to check which foam is used in the design - fire-resistant or regular.

It is important to distinguish between fire resistance and flammability. Flammability is understood as the ability of a material to maintain combustion, and fire resistance is the ability of a material to maintain integrity (E) and heat-insulating properties (I). Fire resistance tests are carried out for joints with a depth of 100 and 200 mm and a thickness of 10 to 40 mm. The time is measured in minutes during which the material was able to maintain its integrity and thermal insulation ability when exposed to an open flame.

Fire resistance indicators of KUDO polyurethane foam

When studying the fire resistance indicators of various brands of foam, it should be borne in mind that tests can be carried out for different types of joints: homogeneous from foam and combined from foam and basalt wool. If tests are carried out for a combined seam, this must be indicated in the characteristics. Such seams almost always have higher fire resistance ratings, but this does not mean that the foam itself has a higher fire resistance. It is correct to compare only indicators for seams of the same type.

Rules for working with polyurethane foam

Since polyurethane foam sticks very well to your hands and is very difficult to remove from them, you should always use protective gloves when working with it.

Before use, the container must be shaken so that the components in it are well mixed. If this is not done, you will not be able to obtain high-quality foam at the output.

Since foam polymerizes in the presence of moisture, the surface to be treated must be moistened before applying the foam. At sub-zero temperatures, moisture can freeze on the surface. Therefore, small areas of the surface should be moistened and foamed immediately, preventing the moisture from freezing.

When applying foam, be sure to take into account the amount of its secondary expansion and try to apply the foam so that after polymerization there is no need to trim it. The fact is that a fairly dense film is formed on the surface of the foam, which reduces the hygroscopicity of the foam. If you cut it, the foam's ability to absorb moisture will increase.

After applying the foam, the seam should be moistened again for faster and better polymerization.

Polyurethane foam is destroyed under the influence of ultraviolet radiation, so after curing, the seam must be protected with plaster or another method.

Polyurethane foam

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From now on, during construction and repair work, cracks and voids are filled with polyurethane foam, which is many times more effective than mineral wool, cardboard and tow. (Fig. 1) This is a polyurethane sealant consisting of 2 petroleum components (polyol and isocyanate), as well as stabilizers, blowing agents and catalysts. Polyurethane foam, the volume of which depends on many reasons, can expand 20-40 times.

Factors influencing the volume of polyurethane foam

The main indicator of polyurethane foam is the volume indicated on the label. A liter can from a good manufacturer should contain 30-40 liters of foam. (Fig.2) The amount of sealant sprayed depends on:

Technologies

Polyurethane foam - an economical thermal insulation material
As a rule, many houses are equipped with protection against external temperatures and internal heat loss. However, it happens that in some houses the thermal protection is not effective enough

Polyurethane foam cleaner - selection criteria
Cleaning foam from the surface is quite difficult. When starting work related to foaming, you must immediately buy a foam cleaner in order to be able to remove fresh stains

Macroflex polyurethane foam: technical characteristics
Polyurethane foam Macroflex technical characteristics: has excellent heat and sound insulation characteristics, excellent moisture resistance, durability

Polyurethane foam as insulation
Polyurethane foams are usually intended for sealing seams when installing window and door units and filling small voids

Non-flammable polyurethane foam
Non-flammable polyurethane foam is used for the same purposes as regular foam, but for structures where it is necessary to ensure high fire resistance

Polyurethane foam for polystyrene foam
Polyurethane foam for polystyrene foam, which consists of diphenylmethane diisocyanate and propellant, adheres perfectly to concrete surfaces, brick, plaster, and quickly hardens under the influence of air moisture within 12 hours

The invention by chemists of a simple and at the same time convenient way to seal seams with polyurethane foam made it possible to achieve significant advantages in the quality and speed of finishing work. The advantages of using professional polyurethane foam were so obvious that the material almost instantly migrated from the sphere of industrial construction of buildings to the field of home-made construction. Polyurethane foam has long occupied the first place in the ranking of the popularity of home building materials, along with adhesive tape, lime plaster and plasterboard.

Requirements for polyurethane foam

Standard balloon foam is a solution of polyurethane in a small amount of hydrocarbon solvent and liquefied butane gas, thoroughly cleaned of moisture. The finished mixture is pumped under pressure of several atmospheres into metal cylinders with a volume of 0.35 l, 0.5 l or 0.75 l; liter polyurethane foam packaging can be used for professional purposes.

For industrial foaming of cracks and joints, two-component compositions based on isocyanate and dihydric alcohol are used. The foamed mass is formed as a result of mixing the components and feeding them from the container into the foaming agent. The quality of the foam layer depends on how fully the components have reacted, so the binary version of polyurethane foam is limited only to industrial construction due to its low environmental friendliness.

During the production process, the purest polyurethane is used to fill cylinders with professional polyurethane foam, everything else is pumped into containers for amateur foaming at home. This decision is not a whim of the manufacturer; polyurethane foam of a professional quality level must comply with the technical characteristics of polyurethane foam according to GOST No. 30971-2002.

The list of the most important technical characteristics of polyurethane foam according to GOST includes:

Water resistance, a layer of foam mass laid in the seam between the double-glazed window and the waterproof wall must withstand a cold water pressure of 240 kPa or 2 Atm for five minutes;
Airtightness according to GOST 30971-2002 is defined as the ability of a seam sealed with polyurethane foam to withstand direct blowing of smoke with a pressure drop of 10 PA for 5 minutes;
The thermal conductivity of a polyurethane foam-based joint is standardly assumed to be 0.05 W/(m 2 °C), while a layer of 50 mm should ensure that the dew point inside the joint is at a temperature difference between the room and outside the window of up to 30 o C.

The data provided is used exclusively for designing window structures of panel and brick houses. For home construction, they will be of little help, especially since state standard No. 30971-2002 was formed exclusively for use as a material for sealing joints.

In practice, when choosing a material for foaming holes or gluing insulation on the walls of a house, GOST for polyurethane foam is practically unsuitable. To make a professional choice of which polyurethane foam is better, it is easier and more convenient to use the characteristics provided by the manufacturer. Most of the technical characteristics of polyurethane foam were obtained as a result of practical tests during the certification of the material, so the data is closer to reality than the general provisions of the standard.

Main characteristics of professional quality polyurethane foam

The list of main indicators for polyurethane foam, which must be taken into account when planning its use in home construction, includes:

Working temperature;
Standard expansion of material upon exiting the cylinder;
Pressure on the walls during expansion;
Thermal conductivity of the foam in the cured dry state;
The strength of a foamed monotone polyurethane block without defects;
Density of the material upon completion of secondary expansion;
Time for film formation to touch-free and complete curing under standard conditions;
Heat resistance, combustion front resistance and surface ignition temperature;
The degree of expansion or amount of material obtained from one package;
Maximum water absorption.

Some of the given characteristics are technologically decisive when choosing a method for sealing polyurethane foam. For example, the vapor permeability of cured foam. If it is necessary to seal the joints between the concrete slabs of a panel house, then several types of foam material are used to seal the joints. The first pass of the seam is carried out with the densest mass, in the second a lighter material is laid, but there must be moisture-resistant polyurethane foam with minimal water absorption and resistance to fungus formation.

Yield, viscosity and operating temperatures of polyurethane foam

Output or standard expansion refers to the amount of material from one cylinder. A standard 750 ml container can produce 35-40 liters of foam. The volume of the resulting material during primary expansion, as well as the operating temperature, must be indicated on the polyurethane foam packaging. Essentially, foam viscosity, expansion ratio, and recommended temperature are all related.

Typically, testing a foam mass of a standard composition is performed at a temperature of at least 5 o C. Under these conditions, the repellent gas dissolved in the foam is capable of expanding by 90% of normal. For lower temperatures, substances are added to the composition that reduce the viscosity of the mixture. Such brands are called universal. If isopropyl alcohol and a mixture of propane and butane are added to the polyurethane composition, then the polyurethane foam receives winter status and costs 10-15% more.

Winter polyurethane foam is usually used at temperatures down to -10 o C outdoors in conditions of high humidity. Due to the reduced temperature, the time required to complete the polymerization process may be delayed, so the mounting compound is laid in small layers.

For your information! In conditions when the air warms up above 10°C, the rate of polymerization depends little on temperature; the determining factor in how quickly the material sets is the partial pressure of water vapor. At a humidity of 15%, polyurethane foam can harden up to 20 hours, while at 90% humidity, the foam material sets in just one hour.

In summer, winter grades of polyurethane foam are not used due to the mobile nature of the mass. If the standard foam has a secondary expansion rate of 1.2, then “winter”, laid on a hot day, can expand up to 180%. This increases material loss and at the same time weakens the seam, making it quite porous and saturated with moisture. Instead of the standard density of 17-22 kg/m 3, the result is 12-15 kg/m 3. Therefore, for thick coatings, polyurethane foam with a low expansion coefficient is used.

Durability and fire resistance of polyurethane foam

Polyurethane-based foam material is widely used as an adhesive base for insulation, fastening, decorative finishing, and even to form a load-bearing frame, for example, for sound insulation. It is generally accepted that the standard strength of defect-free polyurethane foam with a density of 18-22 kg/m 3 is 0.3 kg/cm 2 . This is not steel or stone, but it is enough to make foam insulation for a 2 m high refrigerator without any frame.

At the same time, the polyurethane foam itself is not an absolutely harmless material; when planning spraying of polyurethane foam, it should be taken into account that when expanding, professional quality polyurethane foam can create pressure on the walls at a level of 20-30 N/dm 2. This means that when the space between the door frame and the wall foams, the expanding mass presses on the door hinge with a force of up to 60 kg.

Polyurethane foam is available in three fire resistance classes:

B1 - light foam for insulating walls and attics;
Foam material of household and semi-professional type B2;
Professional theme of class B3 - self-extinguishing;
B4 – fire-resistant mass with fillers based on metal silicates.

For example, Penosil Premium Fire Rated Gunfoam. Penosil polyurethane foam is certified for fire resistance class EI 45 - EI 180, effectively protects against smoke and heat pressure of the ignition front.

Professional quality materials

As in any niche of building materials, among the various brands of foam there are very high-quality samples and outright hack work. The latter are most often the result of outright counterfeiting, so it is quite difficult to talk about the characteristics of polyurethane foam.

The best brands on the market

There are quite a large number of high quality polyurethane foam brands on the market:

Materials of the Macroflex trademark;
Polyurethane foam Titan;
Belgian foam Soudal.

Most professional craftsmen call Soudal polyurethane foam number one among high-quality brands of mounting compound. First of all, because of its proven reputation over 50 years of presence on the market. The price for a 0.75 liter package is about 400 rubles.

Tytan polyurethane foam is considered the “workhorse” of most professional finishers, with a low price and a stable level of quality. The product of the German-Polish company Titan has some of the best characteristics:

From one cylinder you can get up to 65 liters of material;
Polymerization of the layer is completed in 30 minutes, after which the material can be processed or re-coated;
The hardened mass of polyurethane foam absorbs only one and a half percent of moisture, the sound insulation level reaches 61 dB, and the fire resistance of the foam material is certified according to class B3.

The cost of packaging polyurethane foam is 250-300 rubles.

The technical characteristics of the Makroflex polyurethane foam 750 ml practically do not differ from the parameters of Titan. The Macroflex material produces up to 65 liters of foam per package with a density of 17-24 kg/m3 and record low thermal conductivity - only 0.03 W/m*K.

At a temperature of about 400 o C, polyurethane foam begins to show signs of ignition, although the material itself is certified as self-extinguishing - B3. The only drawback is related to porosity; unlike Titan, Macroflex is capable of absorbing up to 20% moisture, so the material requires mandatory protection with decorative finishing.

Conclusion

Choosing the right polyurethane foam is always a matter of personal experience and skill in working with the gun and foam. Often the defining characteristic is the mobility and plasticity of the material and the ability to adhere to the most difficult surface options - plastic and concrete. In this case, it is best to entrust the decision on how to choose polyurethane foam to a specialist.