Polyurethane foam output volume. Polyurethane foam: technical characteristics, manufacturers, application, reviews, properties. What does polyurethane foam consist of?

Now it’s hard to imagine how they used to do repairs without polyurethane foam. It now replaces many materials that were previously used as thermal insulation, sound insulation and vibration protection, fasteners connecting elements from various materials, sealing large and small, as well as hard-to-reach cracks, cavities and crevices.

Foam is a polyurethane prepolymer packaged in a container, which, during use, comes out of it under the influence of a propellant (a gas that forces the material out of the container).

After leaving the container, the foam is a light, elastic, finely porous mass of yellowish color. Under the influence of air, the polymerization process begins - that is, the formation, in fact, of polyurethane foam.

At this time, the foam increases in volume, becomes hard and hardens.

The use of foam during installation can significantly facilitate and speed up the work, but in order for the installation result to be as expected, you need to know the features of working with this sealant and its technical specifications.

There are many brands of MP on the market, differing both in some characteristics and in terms of quality.

But there are a number of basic indicators characteristic of the products of any manufacturer:

Foam output volume in liters. This indicator is always indicated on the cylinder, but you need to know that in this case the output volume is indicated under ideal conditions. In fact, it is almost always less than declared.

Extension. During the release of the substance from the cylinder, its volume increases by 30-50%. This is called "primary expansion".
During polymerization, the volume of foam also increases, sometimes several times. This is called "secondary expansion". It is this that can play a cruel joke on an inexperienced builder: expanding and at the same time hardening, the foam can deform structures and even render them unusable. This is especially true for products such as door frames and windows, which can bend under pressure. Therefore, the MP output must be controlled. It is recommended to initially fill no more than 1/3 of the joint volume with foam. If, after curing, the seam is not completely filled, additional layers of polyurethane foam can be applied.
The MP density depends on its expansion coefficient. To obtain a tight seam, you need to use a material with low secondary expansion. When choosing foam, pay attention to such an indicator as the conditional density - the higher it is, the lower the secondary expansion of the seal will be, the lower the risk of deformation of the structure.
Porosity – the stability of the foam in joints depends on it. High quality foam has at least 88% of its total closed cell content, which is a sign of good insulation.
Adhesion is the ability of foam to firmly connect to the base surface. Good foam adheres well to almost all building materials, except the following: polypropylene, polyethylene, silicone, Teflon.
Viscosity – this indicator characterizes the consistency of the foam. The quality of work largely depends on it. Good foam, which has normal viscosity, never slides down under the influence of its own gravity; it holds securely on the surface for which it is intended, forming a strong connection with its material. However, at low and high temperatures, the viscosity of the foam may change, so it is recommended to slightly wet the surface before starting work - this improves the adhesion of the foam. In addition, when purchasing foam, you need to pay attention to the operating temperature range indicated on the packaging.

Drying time. The packaging usually indicates the time it takes for a film to form on the surface of the foam after it leaves the container (usually 8-15 minutes). But during the first few hours you should not touch the formed layer of foam, since damage to the integrity of the film can negatively affect the result. In damp weather, the foam can harden completely in 4-5 hours, but still it is better not to disturb it during the day. After this time, you can cut off excess foam, plaster, putty or paint it.
Foam shrinkage should not exceed 5%. Otherwise, during polymerization, the material may deform, forming tears, which will cause poor-quality sealing of the seams. Professional material usually has a shrinkage of 0-3%, but for household foam this figure can reach 7%.

Additional characteristics of the MP allow you to get an idea of how it will work in certain conditions.

These include:

fire resistance class;
tensile strength;
compressive stress;
shear strength;
thermal conductivity.

These characteristics give an idea of the likely behavior of the foam in the joint, provided that the structure is subject to deformation or heating.

When purchasing foam, inquire about the presence of a quality certificate.

In many ways, the characteristics of an MP depend on its purpose, so you need to know where and for what it will be used.

Polyurethane foam can be classified according to different criteria. For example, it is divided into household (or semi-professional) and professional.

The professional one is used only with a special gun, while the household one comes with a tube through which it is placed into the seam. But the main difference between these materials is that professional foam has much less secondary expansion and therefore does not have a deforming effect on structures. There is also a difference in cost; professional material is more expensive.

But depending on the purpose of the foam, it can be divided differently.

There are four types of foam, which are radically different from each other:

Low pressure foam is a material for professionals that exerts low pressure on structures during polymerization. This foam is safe even for such a fragile material as MDF, the door frames of which are extremely sensitive to thrust loads. An example of such a material is Macroflex 65.
Fireproof foam – fire resistance class B1. It is mainly used during installation fire doors. This material does not burn or melt for 6 hours. There are other areas of its use: sealing seams and joints when installing fireplaces, stoves and other heating equipment; sealing joints in ceilings and filling seams in window and door frames of saunas and baths; sealing of cable channels and places of passage of household electrical wiring. For work at low temperatures, winter fire-fighting foam is produced. Fire resistant foam can be easily distinguished from regular foam by appearance. The regular one has a color from almost white to yellow, the fire-resistant one is pink.
Frost-resistant foam - used for installation outdoors at temperatures up to -10, and some brands up to -25 degrees. While ordinary foam becomes brittle in the cold and loses strength, frost-resistant foam works as usual.
Universal foam - has a very wide range of applications. It can be purchased at almost any hardware store. If you want to do the work efficiently, then it’s worth investing in a can of professional foam; you can rent a gun for it.

If you want to purchase really high-quality material, then do it exclusively in specialized stores with a good reputation. In spontaneous markets, low-quality and even counterfeit goods are often sold.

“Titan” is a material with a dense structure and low rates of secondary expansion and shrinkage. Often used by professional installers as a means of thermal insulation of pipelines. As for the foam yield, the figure is average. The foam is afraid of ultraviolet radiation, so it must be protected from the sun as soon as possible after installation.
“Makroflex” is a foam of a homogeneous structure with good adhesion. The output corresponds to that declared by the manufacturer. The downside is that the foam is often counterfeited.
“Soudal” is a high-quality, non-shrinking, finely porous foam. The material is non-toxic. They are produced in several versions - summer, winter, fire-resistant. When exposed to light, it quickly begins to crumble and requires protection.
Penosil is a material with a high yield and low secondary expansion. The foam is not intended for outdoor use - at temperatures above +35 degrees it stops foaming.
“Moment Montazh” is a material with a fairly dense, homogeneous structure. Has the property of being well colored. The disadvantage of foam is the high rate of secondary expansion, therefore it requires strict dosing during operation. After a couple of years, the elasticity of the applied material decreases.

Even if when purchasing foam you do not consider products from other manufacturers other than those listed above, you can easily purchase required material, optimally suited for your purposes.

for what purposes the sealant will be used;
at what time of year the work will be carried out - this determines what material you will buy: summer foam, winter foam, universal foam;
How critical is the secondary expansion of the sealant in your situation (choose household or professional);
Whether in your case you need such quality of material as fire or frost resistance - you should not overpay for unnecessary options.

Polyurethane foam

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to enlarge ]

From now on, during construction and repair work, cracks and voids are filled with polyurethane foam, which is many times more effective 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 well to concrete surfaces, brick, plaster, and quickly hardens under the influence of air moisture within 12 hours

Sealing agents are indispensable in construction. The most popular among them are sealants and polyurethane foam. Many people still confuse these types of sealing mastic, thinking that they are the same thing. Actually this is not true. Polyurethane foam is not a sealant in the full sense of the word. Polyurethane foam is used to seal seams and joints with a width of 3 cm. Sealants are used to seal joints and seams no more than 3 cm

Polyurethane foam, in turn, is a stable chemical structure, with low dead weight and high internal concentration. Polyurethane foam is sold in metal aerosol cans. Shake it well before use. One cylinder provides up to 40 - 45 liters of finished foam. The polyurethane foam hardens under the influence of air moisture. During the hardening process, the polyurethane foam significantly increases in volume, forming a porous mass with excellent heat and sound insulating properties. Polyurethane foam is used for gluing, fixing, sealing seams, heat and sound insulation.

Polyurethane foam can be professional (pistol), semi-professional, summer, winter and all-season.

Polyurethane foam (abbreviated MP) is sold in cylinders containing a liquid prepolymer and a propellant (propellant gas). When the contents “come out” of the container under the influence of air humidity and surface moisture, a polymerization (hardening) reaction occurs. The end result is a fairly rigid polyurethane foam. Here are the main properties of foam for which builders value it so much:

mounting (attaches, connects individual parts of the structure),
soundproofing,
thermal insulation,
sealing

In addition, polyurethane foam has other undoubted advantages.

Firstly, the MP, expanding, fills all hard-to-reach cavities and joints.

Secondly, it is self-hardening, so working with it is convenient and easy. For comparison: earlier, instead of foam, cement and tow were used for such work. First, the cement was diluted with water, then mixed with tow. In a word, the installation process was long, multi-stage and often ineffective. Now, just one can of polyurethane foam is enough to get the same result and even better without much effort.

Thirdly, MP is a universal material: more than a thousand options for its use in construction and industry are now known

Another indisputable advantage of polyurethane foam: it is designed to work with all traditional building materials(wood, stone, concrete, plaster, metal, glass). The only exceptions are polyethylene, polypropylene, Teflon, silicone, etc.

Application of polyurethane foam

Polyurethane foam has occupied that part of the market that, before its appearance, was dominated by traditional materials - cement, cork, bitumen, mineral wool tapes, plaster, etc. MP has established itself as a universal insulating material that fills cracks, glues surfaces, is moisture-proof, does not conductive of electricity, fireproof (this indicator depends on the flammability class of the MP). All this makes it possible to widely use polyurethane foam for sealing and sound insulation, and gluing materials. So, let's take a closer look.

Insulation (sealing)

Filling cracks in cold rooms (insulation);

Filling cracks and crevices in roofing materials;

Filling voids around window and door frames, as well as other structures;

Bonding

Fixing door and window blocks (and then there is no need to additionally screw or nail with screws or nails).

Fastening insulating and insulating materials to the walls (if it is necessary to insulate a room, for example, with polystyrene foam boards, the question often arises: how to glue the boards to the wall? The simplest solution is polyurethane foam).

Soundproofing

MP allows you to reduce noise that occurs during the operation of pipelines, air conditioners or space heating systems. Foam is used to seal the junctions of hoods and air conditioners, and the gaps between pipes. And since there are no cracks, it means there will be no rattling or noise. Use of foam in everyday life

Installation of window and door blocks.

Filling cracks and voids during repairs and construction in country houses and city apartments.

Widely used during indoor renovations (for example, fastening wall panels, etc.).

Polyurethane foam can be used to seal cracks and holes on floating craft (boats, rafts, etc.)

As you can see, the possibilities of polyurethane foam are not limited. The only thing is that you need to know well how to use it correctly. To do this, we advise you to carefully read the instructions for use. The final result depends on how competent your actions are.

Method of application.

Professional. This name is more of a household name. Manufacturers call it pistol foam. It differs only in the presence of working cylinder valves, that is, pistol foam is used using a special mounting gun. A mounting gun is a device that is placed on a special cylinder valve designed specifically for it; thanks to it, foam is supplied and dispensed into cavities and crevices. Why is it still “professional”? Yes, because such a mounting gun costs 10 or even 15 times more than the foam container itself. And there is absolutely no point in purchasing it for one-time housework. Such guns are used by professionals, namely builders and repairmen who daily have to work with polyurethane foam sealants.

It is much more convenient to use the mounting gun thanks to the ergonomic handle and dispenser trigger; in addition, the gun has a long metal barrel, which allows you to work in hard-to-reach places. But caring for the gun requires additional costs; after each use it must be washed with a special cleaning agent, which frees the working cavities of the device from the remaining unhardened foam. The cleaning agent itself is also under pressure in a cylinder, which has special nozzles that simplify cleaning.

Semi-professional. Polyurethane foam, the use of which does not require any additional devices (paint guns). To spray polyurethane foam, put a special plastic tube with a lever (adapter) attached to each cylinder onto the valve. This is quite convenient and practical for a small amount of work. If you have not used up all the foam from the bottle, you can remove the tube, wash it with acetone or a special cleaning agent and put it aside along with the unused bottle until next time.

Use temperature

Summer foam. The cans indicate a temperature from +5°C to +35°C, this means that the temperature of the surfaces being treated must be within this range. But this does not in any way affect the temperature resistance of the hardened foam - for both summer and winter it ranges from -50°C to +90°C.

Winter foam. The operating temperature of this foam ranges from -18°C (-10°C) to +35°C. It should be noted that the volume of foam after its spraying and expansion (foam yield) decreases in proportion to the decrease in ambient temperature. For example, the foam yield from a 300 ml container at a temperature of +20°C is 30 liters, at 0°C - about 25 liters, at -5°C - about 20 liters, at -10°C - about 15 liters.

All-season foam. It has absorbed all the best from the summer and winter modifications; its special formula allows you to obtain a high foam yield, a fast polymerization process and work at low temperatures down to -10°C with an unheated cylinder. All-season foam is a new product and therefore is not included in the product range of all polyurethane foam manufacturers.

Cylinder capacity

The foam output from a cylinder intended for use with a mounting gun is more abundant than from a conventional cylinder of the same volume, due to more high pressure in a cylinder that allows you to refill large number source material.

300 ml - foam yield up to 30 liters, which makes it possible to process one standard door frame with a gap of three to five centimeters.
500 ml - foam yield 35-40 liters, under the same conditions - one and a half door frames.
750 ml - foam yield up to 45-50 l - two to two and a half standard door frames.

Here are some tips that will help make working with polyurethane foam easier and get the desired result.

Preparation for use. Since polyurethane foam sealant contained in cylinders hardens under the influence of air humidity, it is advisable to additionally moisten the surface with water before application: the expansion and rate of hardening of the foam (polymerization) will increase.

When working with polyurethane foam is carried out at sub-zero temperatures, the surfaces being treated must be cleared of ice and frost.

Before use, the container should be shaken well for about a minute and warmed (without using open flame! Flammable!) to room temperature (from +10°C to +25°C). These measures significantly increase the foam yield and density.

If you plan to process window and door frames, to prevent distortion, you need to install additional spacers in them, which should not be removed until the foam has completely hardened.

Usage. When spraying, the container must be held upside down, otherwise all the air will escape and the container will remain without pressure, thereby becoming unsuitable for use.

The seam is filled from the bottom up using uniform V-shaped movements, leaving approximately half the volume of the gap for the foam to expand.

Cavities deeper than 50 mm are filled in several stages, waiting for each layer to dry.

Please note: despite the fact that polyurethane foam has strong adhesive properties, it is not intended to work with polyethylene and silicone surfaces. It simply does not stick to these materials.

After use. Uncured foam from clothing and other items can be removed with acetone or a cleaning agent specially designed for this purpose.

The average time for initial drying of the foam (you can touch it) is about 10-20 minutes. The foam completely hardens after 4-6 hours, this time directly depends on the temperature and humidity of the surrounding air.

Excess, protruding fragments of foam can be cut off with a knife.

Cured foam does not withstand exposure to sunlight, so during external work, after final hardening, it must be additionally protected with paint or plaster.

Additional Precautions

Uncured foam irritates the skin, respiratory tract, and eyes. Therefore, during work you need to use protective gloves and goggles, and if there is insufficient ventilation and a high concentration of vapors, use a respirator. Hardened foam is not harmful to human health.
When purchasing foam, you may stumble upon a fake. How to avoid this? After all, polyurethane foam produced in artisanal conditions without compliance necessary technologies, may not live up to the generous promises of the label. Unfortunately, we constantly hear about the discovery of yet another warehouse of counterfeit goods. It is worth recognizing that there is no unique, fail-safe way to identify a fake. All kinds of special signs and holograms are not a guarantee of quality; they are counterfeited with great success by scammers, since these people learn about the mandatory presence of certain protective signs on foam cylinders much earlier than us, the consumers. All that remains is to use general recommendations that are suitable for most consumer goods, namely:
- ask the seller to show the certificate of conformity for this product;
- look at the printing quality of the label or the quality of the image applied directly to the cylinder. Since counterfeits are often produced at minimal financial cost, little importance is attached to the quality of printing. Therefore, the label (balloon with the image) looks sloppy, and often the naked eye can see the shift in colors, which is why small text becomes unclear;
- pay attention to the date of manufacture (usually the shelf life of the foam is one year from the date of production) - expired polyurethane foam has most likely already lost all its valuable qualities.

Who produces it?

Our market is currently overcrowded with all kinds of polyurethane foam, but this does not mean that all the products offered are of high quality. A lot of polyurethane foam that does not meet certain requirements reaches the shelves of stores and especially markets: for example, when gases harmful to the ozone layer are used as a propellant. Or there are cases when manufacturers simply do not add polyurethane foam into the cylinders.

Unfortunately, many Russian traders (fortunately, not all) put the price first, and not the quality of the polyurethane foam they sell. And our consumers “help” them with this. After all, the average buyer has practically no idea what the foam should be (how much of it should be in the cylinder, what quality...).

If there is a need to fill a hole, seam or gap, polyurethane foam is most often used. This material is used for rough finishing, installation of door frames, double-glazed windows, repair of balconies, construction of various buildings (for sealing).

There are several types of polyurethane foam - for different conditions and tasks.

The product is sold in cylinders of different sizes (from 300 ml to 1 l).

Approximate composition (may vary partially, depending on the manufacturer and type):

Prepolymers (polyol, isocyanate) are the basis of the foam. Upon contact with air, this component enters into a polymerization process, expanding and foaming.
Propellant (propellant gas, a mixture of butane and propane). Displaces the composition from the cylinder when pressed.
Additives. Additional components that improve adhesion, regulate the degree of foaming, are necessary to change the operating temperature.

Specifications

Technical characteristics of polyurethane foam:

Extension. Indicates the volume that the mixture occupies at 2 stages: leaving the container and solidifying. The greater the expansion, the denser the gap (seam, hole) will be foamed. Average figures are 10-60% for household compositions, and 180-300% for professional compositions.
Adhesion. Indicates the tenacity of the composition with the surface inside the foamed space. The higher the viscosity, the less the foam will slide off. This is relevant if you need to foam holes on a vertical surface (on the wall) or on the ceiling (from where the foam can drain before it hardens). In numbers, the normal parameter is considered to be 0.4-0.48 MPa.
Volume in container and volume out. Common parameters: 300 ml (will give about 30 liters of hardened foam), 500 ml (will give about 40 liters of foam), 750 ml (will give up to 50 liters of foam) and 1000 ml (80-100 liters). The volume of frozen foam is given approximately under normal conditions (room temperature).
Temperature at which foam can be applied.

These characteristics are indicated on the cylinder.

Purpose and scope

Polyurethane foam is used in construction at the following stages:

Rough finish.
Installation of door frames, balcony and window frames.
Communication laying (for sealing between water pipes, sewer pipes, ventilation ducts, gas pipelines and the wall to prevent vibration).

Its purpose is to seal holes, cavities, seams and joints between structural elements if their width exceeds 2-3 cm. Previously, cement and tow were used for such tasks, but this method is longer and more complex.

Pros and cons of using foam as a sealing material

The advantages of the application include the following nuances:

Easy to use (working with polyurethane foam does not require special experience or knowledge).
High speed of application and hardening (a 300-500 ml container can be completely released in 5-10 minutes, it will harden in 3-12 hours, depending on air humidity and temperature).
Can be used with any type of material, including metal, plastic and polymer surfaces.
Strong adhesion to surfaces (after hardening, it will be difficult to remove the foam, but if necessary, it can be cut off or washed with a solvent).
Resistance to moisture (the layer of hardened foam does not rot or mold).
Availability of compositions with different characteristics (for different temperatures, with different degrees of protection from open fire).

The main disadvantage is its sensitivity to ultraviolet radiation. Under sun rays the foam dries out over time, but it is usually used at the rough finishing stage, and is not left in sight - it is either sealed with plaster or covered with panels (plastic, for example).

Types of polyurethane foam

All compositions can be divided into:

Number of components.
Method of application.
Temperature.
Degrees of flammability.

By number of components

There are compositions:

One-component. Sold in pressure cylinders, they do not require additional components: the composition can be used immediately by spraying it from the container.
Two-component. Sold in 2 separate containers. The contents of the containers must be mixed in certain proportions, and the resulting mixture must be applied using special devices.

In construction stores, most of the products are one-component compounds. Two-component ones are usually used only for industrial purposes, for large volumes of work and when it is necessary to obtain the highest possible characteristics of the composition.

By method of application

There are compositions:

Professional. The foam is sprayed from a container, which is inserted into a construction gun. A more convenient option than spraying with a tube allows you to quickly work with a large volume (for example, foaming cracks between slabs).
Semi-professional (household). A plastic tube is placed on the container through which the mixture will pass. Suitable for small volumes (for example, to foam a gap when insulating a balcony).

Plastic tube nozzles are sold complete with small volumes. They can be used several times (if the work is carried out in several stages, if several cylinders are used), for which it is necessary to blow out the tube after use (so that the foam does not freeze inside).

Foam guns are sold separately. The minimum cost is about 300 rubles, the average is 500-800. The device is reusable; at the end of work it must be washed with a special cleaner (containing an acetone solution). Even if the foam hardens inside the nozzle, it can be washed off with a cleaner or cleaned mechanically.

According to the temperature at which the foam can be used

Based on temperature conditions, the following types of compositions are distinguished:

Summer: intended for use at +5º…+35º.
Winter: intended for use at −18º…+35º.
Universal: used at −10º…+35º.

The temperature of the surfaces on which the foam is applied is indicated, not the air temperature in the room. Therefore, when working in cold weather (for example, if a balcony is being glazed in winter, or the seams are foaming in a building under construction without heating or without windows), it is necessary to heat not the room, but the surface.

Also, the surface temperature affects the volume of polyurethane foam: the colder it is, the less ready-made solution will be produced at the exit.

According to the degree of flammability

This is relevant if work is carried out in a room with the possibility of fire (for example, in a bathhouse).

Product classes:

B1: Fireproof.
B2: self-extinguishing.
B3: flammable.

Popular manufacturers

There are products from the following manufacturers on the Russian market:

Macroflex (Makroflex, Finland).
Bison International (Netherlands).
Soudal (Belgium).
Tytan, Hauser (Poland).
Bau Master, Domos (Estonia).
Master Gvozd, CHIP, Putech (RF).
Ceresit (Germany).

Rules for using polyurethane foam

Foam is used observing the following rules:

The width of the crack or hole should be in the range of 2-10 cm. Narrow cracks (up to 2 cm) are best sealed with putty or sealant. It is better to seal wider cracks with brick, wood or foam, and foam the remaining leaks.
When working in cold weather, the foam container will need to be heated: lowered into a container with warm water (up to approximately 30-40º).
You can cut off the excess only after 25-30 minutes after applying the foam, when it has completely hardened. This can be done with a construction knife.
The cylinder must be held upside down so that the gas pushes out the foam. If you hold the container upside down, the gas will come out of the container, but the foam will remain.
After removing the cap and attaching it to the gun (or tube), the can must be shaken.
A container with “household” foam is used completely in one go - an open container cannot be stored for a long time, it will harden.
The gap cannot be foamed more than 50%, because when it expands, its volume increases.

Complex nuances

To avoid having to cut off a large amount of foam and redo the structure again, keep in mind:

If the hole is 3-4 cm wide or more, the foam is applied in several steps: first 1 layer, after it hardens - the next ones in succession.
It is better not to fill through holes with foam. On the one hand, it is recommended to cover them tightly with something (for example, a board), and remove the “lid” only 30 minutes after foaming, when the composition has hardened.
When installing door and window frames, they must be secured with dowels and spacers. If this is not done, the expanding compound may warp the box and it will have to be reinstalled.

Stages of work

The foam is used step by step like this:

The surface is cleaned of small debris, if any.
The surface is degreased (acetone).
The surface is moistened (sprayed with water using a brush or spray). Foam hardens faster and better if the surface (or air) is wet.
If the room is cold, place the balloon in warm water.
The cylinder is opened, inserted into the gun (or a tube is put on it) and shaken.
The end of the tube is inserted into the slot, and the foam is supplied in portions, 5-10 cm along the length of the slot, moving from bottom to top.
After complete hardening (after 25-30 minutes), the protruding pieces are cut off with a construction knife.

Safety precautions when working with polyurethane foam

Polyurethane foam - chemical composition, located in a container under pressure. Therefore, you need to work with it, observing safety rules:

Do not drop or heat the cylinder.
Do not use the cylinder near hot surfaces or open flames.
The work is carried out with gloves (if the foam gets on the skin, it will be difficult to clean it off).
You need to keep a sponge and a rag on hand to clean off the composition if it gets into an “unwanted” place.

Removing foam from contact with “unnecessary” surfaces

Polyurethane foam sets quickly on the surface, so if it gets somewhere other than the desired gap, it will be difficult to clean it off.

Methods for cleaning different surfaces:

Leather. If the composition has not hardened, it is removed with a sponge, and the remains are washed with acetone or a solvent. If it is frozen, it is cut off and scrubbed off with a scrub.
Textile. The uncured composition is collected with any hard object (a piece of a board will do). The frozen pieces are cut off, and small residues are washed off with a solvent. In both cases, a stubborn stain may remain on the fabric.
Plastic window sills, frames, slopes. Fresh composition is removed with a sponge, the remains are washed off with a cleaner for plastic surfaces. The dried layer is cut off, the remains are washed off.
Linoleum, laminate. Fresh foam is removed with a hard object (a spatula, a piece of board), the remains are collected with a sponge soaked in cleaner.

To prevent such situations, in addition to the skin, it is necessary to protect the surfaces around it. It is advisable to cover them with plastic wrap, rags or newspapers.

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 commonly referred to as 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 to quickly fix 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 others. 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 various characteristics, for example, 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 canister 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 may vary from manufacturer to manufacturer. different types foam varies from 15% to 60% for professional foam and from 200% to 300% for household 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 dimensions of ±10% are acceptable for installation 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 more ahead of schedule 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 species foam, the air temperature usually ranges from +5°C to +35°C; the highest quality winter ones, 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, while 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 a while. 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. For selection optimal temperature 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, you should definitely 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.