Thanks to the excellent gas support properties, Evoh Small is mainly used as a functional barrier in food packaging. Keeping oxygen and moisture, this layer retains the taste and quality of food. Even in cases where food is more stable or specially processed, for example, baby milk, the barrier properties of the layer are used to protect the sensitive content of vitamin

Resistance to industrial chemicals

EvOH is opposed to oils and chemicals, which makes it particularly suitable for packaging organic solvents, agricultural pesticides and all types of oils, while maintaining all the benefits of plastics. As a result, the 5-layer film with the barrier layer provides safe use with solvents and other chemicalsSimultaneously protecting their integrity.

Process efficiency

The presence of this layer leads to a reduction in production costs and a decrease in packaging waste.
Plastic barrier films can be designed for aseptic filling, due to which energy consumption is reduced during processing. No hard designs with a barrier layer allow you to transport more products instead of unnecessary heavy packaging. Inexpensive, but functional design Packaging helps to withdraw high-quality products into new markets.

The advantage of excellent gas-targeted properties is less raw material (for example, plastic), which can be used without loss of performance. As a result, the packaging is easier by weight and does not contain chemicals that damage environment. In addition, waste containing the barrier layer can be retrieved and recycled.

Stitched polyethylene tube with outer diameter 16 and wall thickness 2 mm. Designed for domestic systems of cold and hot water supply, low-temperature (up to 80 ° C) heating. Classes of operation according to GOST 52134-2003 - 1, 2, 3, 4, KH. The design of the pipe includes a layer of polyvinylethylene (EVOH), which prevents the diffusion of oxygen into the coolant.
The installation of PEX-EVOH polyethylene pipes is performed using Valtec press fittings. Estimated service life - 50 years.

The material of polyethylene pipes Valtec PEX-EVOH is stitched polyethylene (PE-X). It is obtained from the usual high-density polyethylene by special processing, which ensures the occurrence of bulk bonds between linear polymer molecules. This gives products thermal stability, mechanical strength, high elasticity, increased resistance to ultraviolet radiation. In addition, cross-linked polyethylene pipes are characterized by low roughness of the inner surface, are not subject to corrosion, not separated into the stream. harmful substances In the operating range of temperatures, electrically inert, do not distribute (on the contrary - absorb) noise and vibration, withstand without destruction freezing of the liquid. The estimated service life of such products is 50 years. Polyethylene pipes Valtec PEX-EVOH is designed for engineering systems, including - for a warm floor, and technological installations With operating temperature up to 80 ° C (at operating pressure of 6 bar). Briefly assume the heating of the transported medium to 95 ° C. The design of pipes includes a layer of polyvinylethylene (EVOH), which prevents the diffusion of oxygen into the coolant. Installation of PEX-EVOH pipes are made using Valtec press fittings. The sizes are specified outside diameter And the thickness of the wall of the pipe. Form of delivery - bays of 200 m.

Today, the share is growing in Russian construction low-temperature systems Heating. Modern boilers I. heating devices Capable to fully damn rooms with a temperature of the coolant to 80 ° C. In addition, the system has recently received widespread outdoor heating. The temperature and pressure of the coolant in these systems allow you to use simpler and cheap materials. That is why on russian market Now there are great demand for stitched polyethylene pipelines. This species Pipelines combines reliability when used in low-temperature heating systems, ease of installation and low cost.

Stitched polyethylene pipeline, or, as it is called, Pex pipe is practically monolithic design, the main material of which is molecular-stitched polyethylene. The usual polyethylene consists of long hydrocarbon molecules that are not connected with each other and is not suitable for use as the main material of pipelines of heating systems due to low heat resistance. Molecular-stitched polyethylene has transverse links between the chains of hydrocarbon molecules, and therefore this material It has higher strength and stiffness and most importantly - higher resistance to temperature effects.

If we talk about metal-polymer pipelines, then under this term today is made a rather extensive class of polymer pipelines, the main difference of which from ordinary pipelines is the presence of a reinforcing layer of metallic, usually aluminum, foil between the inner and outer layer of polymer. At the same time, the same material can be used as the material of the inner and outer layers as in PEX-pipes, namely crosslinked polyethylene. Other materials - polyethylene (PE, PE-HD), polyethylene elevated temperature resistance (PE-RT), polypropylene (PP-R), etc. can also be used.

While the characteristics of metal-polymer pipes are often dependent on the properties of the materials used and the quality of the adhesive layer, the characteristics of PEX pipes, as a rule, depend on the degree of crosslinking of polyethylene, the thickness of the pipeline wall and the method of applying oxygen-resistant layers.

Polyethylene stitching determines the strength and thermal characteristics of the pipeline. First of all, the stitching allows you to achieve long-term resistance to high temperatures and pressure (increases the limit of logarithmically proportional relaxation). Polyethylene stakes can occur different ways and with varying degrees. There are three basic industrial fashion Polyethylene stitching:

• the peroxide method (PEX-A) is a chemical method of crosslinking polyethylene and consists in stitching with organic peroxides and hydroperoxides. The pipeline obtained at this method has a crosslinking degree of about 75%;
• the silane method (PEX-B) is also chemical. When stitching this method, organosilanes are used. The minimum coefficient of stitching by this method is limited to 65%;
• radiation stitching (PEX-C) is performed using the flow of charged particles. The crosslinking coefficient is about 60%.

Valtec PEX-EVOH pipelines pass the hollow processing cycle with a silane method (PEX-B) on modern equipment, due to which a uniform crosslinking of polyethylene with a degree of crosslinking is 68-70%.

The method of stitching pipelines is practically no effect on physical properties finished pipeline. The properties of the pipeline mainly affect the degree of stitching. With an increase in the degree of crosslink, the strength, heat resistance, resistance to aggressive media and ultraviolet rays. However, together with an increase in the degree of crosslinking, fragility increases and the flexibility of the obtained pipeline is reduced. If you bring the degree of stitching polyethylene to 100%, then in its properties it will be like glass.

Also, the stitching of polyethylene gives the resulting pipeline "Form Memory". Its essence is that the pre-deformed pipeline after heating restores its original form. This property is manifested due to the fact that during bending and deformation, molecular-related areas are compressed or stretched. After warm up in places of deformation, internal stresses occur, at the expense of which the initial form is restored ( fig. one).

Flaw and Restoration of the shape after warming up to 100 ° C Valtec PEX-EVOH pipe (method of stitching - pex-b)

Fravel and reduction of the shape after warming up to 100 ° C pipe from PEX-A with an antidiffusion layer

Fravel and reduction of the form after warming up to 100 ° C pipe from PEX-C without an antidiffusion layer (unpainted stitched polyethylene at high temperature becomes transparent)

Fig. 1. Restoration of the shape of pipelines after deformation

On the fig. one The restoration of pipelines with various ways of crosslinking after a break is shown. With all the methods of stitching pipelines restored their original shape. On the pipelines coated with an antidiffusion layer, folds were formed after recovery. In these places, the antidiffusional layer was peeling from the PEX layer. This defect practically does not affect the characteristics of the pipeline, as the main carrying ability The pipeline determines the PEX layer, which is fully recovered. A minor detachment of the antidiffusion layer insignificantly increases the oxygen permeability of the pipeline. The pipeline without an antidiffusion layer after heating becomes transparent. This effect Inherent in any unpainted stitched polyethylene.

The memory effect of the form is very useful when mounting. If during the installation of the pipeline is formed a break, squeezing or other deformation, then it is easily eliminated by heating the pipeline to a temperature of 100-120 ° C. In addition, when performing a compound of a PEX pipeline with a fitting, strains are also arisen in the strokes of the fitting ( fig. 2.). When serving the coolant and heating the pipeline, restoring efforts occur in these places. Due to these efforts, the pipeline is densering the fitting, which increases the reliability of the connection.

Fig. 2. Connection of the PEX pipe Valtec with a press fitting

Fig. 3. Bending PEX pipe with a diameter of 20 mm for a radius of 100 mm

The selection of a 68-70% polyethylene sewing degree of 68-70% for Valtec PEX-EVOH pipelines is due to the optimal ratio of the strength characteristics of the pipeline and its flexibility. For example, the Valtec Pipe can be manually room temperature bend to a radius equal to five pipe diameters ( fig. 3.), and when using a pipe bender or conductor - to a radius equal to three diameters. The pipeline with stitching more than 70% will have a bending radius manually at least seven diameters. A larger bend of the pipeline with such a degree of crosslinking can be achieved only when using a construction dryer.

It should be noted that PEX-pipelines are fairly elastic and poorly bent. After the "cold" bending, the pipe cut will be initial. However, if you pre-warm the pipeline and give it to cool in a fixed position, it will save this position. When recreating the pipeline, the segment will return to its original state due to the memory effect effect.

The effect of form memory should not be confused with elastic deformation. In the first case, the initial form is taken only after heating, and in the second immediately after removing deforming efforts and only within the limits of elastic deformation (without fractures).

PEX-EVOH pipelines VALEC firm permissible to be offered in building construction Both with a casing and without casing. When the PEX-EVOH insulating pipes in the casing, there is the possibility of replacing small areas of pipelines without opening the floor.

The wall thickness of the pipeline directly affects the maximum pressure of the coolant, which can withstand the pipeline. Valtec PEX-EVOH pipes are made from the same wall thickness, as well as in metal-polymer pipelines - 16 x 2.0, 20 x 2.0 mm. This allows you to use standard press fittings for metal-producing pipelines for mounting pipelines.

The disadvantage of PEX material is that it is oxygen-permeable. Water in the pipelines without oxygen protection at a certain time is saturated with oxygen, which can lead to corrosion of system elements. To reduce the oxygen permeability of Pex, a thin layer of polyvinylethylene (EVOH) is used. The main layer of PEx and the EVOH layer are connected to the glue. It is worth noting that the EVOH layer does not prevent completely oxygen emission, but only reduces oxygen permeability to a value of 0.05-0.1 g / m 3 · day, which is permissible for heating systems.

In the Valtec PEX-EVOH pipe, the antidiffusional layer is executed outside, i.e. Pipe has three-layer design: PEX-Glue-Evoh. The market also meet five-layer (PEX-Glue-Evoh-Glue-PEX) pipes ( fig. four).

Fig. 4. Construction of five- and three-layer Pex pipes with antidiffusion layer

This design is designed to eliminate the possibility of damage to the EVOH layer. However, the tests have shown that the three-layer tube (with the applied EVOH layer outside) is more reliable than five-layer. The increased strength of the three-layer pipe is due to the fact that the PEX layer is monolithic throughout the pipe cross section, in contrast to the five-layer, in which the PEX layer is interrupted by a layer of EVOH and glue, which is due to the internal transverse intermolecular bonds of polyethylene. Also, with this design, the pipe bundle is possible when it overheats it construction phenomenon During bend.

The view is that outer layer Evoh in a three-layer construction is susceptible to abrasion, erroneously. The hardness of the EVOH layer is significantly higher than that of the PEX layer, therefore, with proper transportation, damage to the outer layer is unlikely.

Stitched polyethylene pipelines are recommended for the device of low-temperature heating systems. The use of PEX pipelines for high-temperature heating systems is not prohibited. But it should be noted that, at the same time, the allowable maximum pressure of the pipeline will be much lower than the passport. In addition, the estimated lifetime of the pipeline in such a system will be reduced.

Pipeline manufacturers mainly set the maximum operating temperature and pressure based on the service life of the pipeline - 50 years. When deploying and hidden gasket, replacing pipelines data can be performed jointly with overhaul Buildings or premises. The more frequent replacement of deployed pipelines will entail large financial costs for alteration of the building designs.

But the temperature of the coolant during the operation of the system is different. In the summer and in the transition period, the temperature of the coolant is lower than the calculated one. To assess the applicability of pipelines to a certain temperature regime In the conditions of the changing temperature of the coolant, the standards of operation are defined by standards. These classes show the shares of the effect of different temperatures from only fifty summer period operation.

Pipe SL SLIDE made of stitched polyethylene with the PEX-B / EVOH barrier layer are designed for use in radiator heating, Water supply and water heating floor systems.

SLIDE pipes from stitched polyethylene are produced at the Metserplas plant (Israel).

Pipe SL SLIDE from stitched polyethylene with a barrier layer PEX-B / EVOH have a number of advantages.

EVOH barrier layer prevents oxygen penetration into the pipeline system. Heating elements and are not subject to corrosion. The inner layer of pipes is resistant to abrasion. Ideally smooth inner surface The walls do not contribute to the deposition of stiffness salts, scale, scale, etc.

Pipe SL SLIDE from cross-linked polyethylene PEX-EVOH is environmentally friendly to use, due to the absence of toxic and physiologically harmful discharge.

Also pipes SL SLIDE from cross-linked polyethylene PEX-EVOH distinguishes sacchability to use, unlike metal.

The SL SLIDE PEX-EVOH pipe consists of three layers: stitched polyethylene, an outer antidiffusion layer and connecting their adhesive composition.

The structure of polyethylene is not uniform. It has amorphous and "crystalline" zones. The most effectively stitching occurs in amorphous zones, starting at a temperature of + 125 ° C.

Stitching occurs in the "crystalline" zones. When cooled, the stitching process continues in finished pipes in air and accelerates in hot water. The minimum percentage of crosslied molecules (stitching) mounted standard for PEX-B pipe is 65%.

Pipes with a small crosslinking percentage (less than 60%) are not recommended to be installed in radiator heating systems.

SP SLIDE PEX-EVOH pipe specifications

Outer diameter - 20 mm
Wall thickness - 2.0 mm
Cove Length - 100/200 m
Scope - Water Heat Paul
Service life - up to 50 years
Maximum operating temperature - 95 ° C
Working pressure - 10 bar
Diffusion oxygen per day - 0 mg / m3
Emergency temperature, (max 1 hour) - 100 ° C
Degree of stitching - 65-85%
The coefficient of thermal conductivity - 1.2-1,4х10 -4 W / m * to
Linear elongation at a temperature of 95 ° C - 3% per 1M
The coefficient of thermal conductivity - 0.32 W / m * with
Volume 1 pm Pipes - 0,201 l

The film with "EVOH" is a statistical copolymer of ethylene and vinyl alcohol. This is a crystalline polymer that has a molecular structure represented by the following formula:

Films of 5 layers based on the barrier layer are distinguished by excellent technological ability and excellent barrier properties. The key to this wonderful balance is the combination of proper copolymerization of ethylene with vinyl alcohol, a carefully selected polymerization degree and a uniquely patented production process, which is used in the production of EVOH copolymers. These unique polymers are blown in the process of a 5-layer film, and these films are particularly suitable for food, medical, pharmaceutical, cosmetic, agricultural and industrial packaging.

Evoh.

Evoh.

The quality of products occupies an important place in the production, but the packaging of this product is not inferior in the importance of the intended result, namely its delivery to the final consumer. Here you need a presentable type and reliability when storing and transporting. To solve such tasks in the industry to create a film material, various kinds of packaging are developed that satisfies the most trusted queries of manufacturers. This is possible when combining a set of variants of the sequence and layers of film material.

Big breakthrough in technology creation different species Packaging with precise barrier properties is the application Evoh.. This material has unique qualities due to its chemical structure: polyethylene compound and polyvinyl alcohol (PVA). At the same time, the alcohol is responsible for the barrier properties. finished materialAnd polyethylene makes it militant to thermal processing. As alcohol polymers are subject to negative impact moisture, then to EvOH from two sides, polyolefins attach to its protection. And with its combustion, only water and gas and gas is allocated, which makes the material easily dispose of disposal.

Also, the uniqueness of the Evoh lies in the quality, which in its properties allows not only to replace such expensive materials like a metal foil, tin, glass, but also whole line The following advantages:

• almost does not have weight;
• not beats;
• has a high degree of transparency;
• allows heating in a microwave furnace;
• it has flexible properties (restores forms after deformation);
• allows you to give the package presentable, original and unique view due to the privacy of holography and all sorts of printing images;
• corrosion cannot be subject to corrosion.