DE202017007631U1 - Thermally insulated medium pipes with cell gas containing HFO - Google Patents

Abstract

Thermally insulated line pipe (1), comprising at least one medium pipe (4), at least one thermal insulation (3) arranged around the medium pipe and at least one outer jacket (2) arranged around the thermal insulation, characterized in that
said medium pipe (4) is designed as a flexible piece of pipe,
said outer jacket (2) is designed as a flexible piece of pipe and optionally comprises a barrier (9) made of plastic, and
said thermal insulation (3) comprises a foam containing polyurethane (PU), the cell gas of which contains 50-100 vol% R1336mzz and 0-50 vol% cyclopentane and 0-50 vol% CO ₂ , and wherein the cell gases add up to 100 vol% or Add together with air to 100 vol%.

Description

The invention relates to pipe systems containing thermal insulation, in particular thermally insulated medium pipes and thermally insulated covering devices or sleeves for connecting line pipes with improved thermal insulation. The invention further relates to methods for producing such devices and to the use of polymer foams which contain hydrofluoroolefins (HFO) in such devices and for producing such devices. Ultimately, the invention relates to the use of HFO as cell gas in thermal insulation.

Pipe systems containing thermal insulation, also called pre-insulated pipe systems, or thermally insulated pipe systems, are known and proven. Such pipe systems include flexible or rigid medium pipes, which are surrounded by thermal insulation, which in turn is surrounded by a jacket, and possibly sleeves and / or covering devices. Depending on the structure, these pre-insulated pipe systems are referred to as plastic medium pipe systems (PMR) or plastic jacket pipe systems (KMR). In the former, the medium pipes used have a certain flexibility, so that the entire assembly can be wound onto drums with a certain amount of force. This is why we also speak of flexible pipe systems. In the latter case, the medium pipes used are not bendable, which is why the entire network is referred to as rigid pipe systems. Accordingly, thermally insulated medium pipes or line pipes with one or more thermal insulation layers are known; also their production. So are out EP0897788 and from EP2213440 Process for the continuous production of thermally insulated medium pipes is known. Out of EP2248648 a method for producing individual, rigid pipe sections is known.

In such pipe systems, the composition of the cell gases in the foam material (e.g. polyurethane, PU) usually used as insulating material changes over time. This is done by diffusion of nitrogen and oxygen from the environment into the foam and by diffusion of the foam or cell gases originally contained in the foam, in particular carbon dioxide and other blowing agents, out of the foam. The air gases have a significantly higher thermal conductivity than the carbon dioxide originally contained and the propellants otherwise commonly used.

In order to minimize these diffusion processes, it was proposed to integrate so-called barrier layers into the outer jacket.

Metallic layers can be used as barrier layers. When using metallic layers, not only is gas exchange completely prevented, which is desirable, but water vapor is also completely prevented from diffusing. This is particularly problematic when using medium pipes made of plastic, since water typically flows through them as a medium, which is why a constant amount of water vapor, even if only a small amount, migrates through their walls. This water vapor must be able to penetrate to the outside or come into equilibrium with the environment, otherwise water will accumulate in the thermal insulation of the thermally insulated pipe over time, causing the thermal conductivity to increase significantly and there is a risk that thermal insulation is damaged in the long term.

Layers consisting of one or more polymeric materials can be used as barrier layers. This describes it EP1355103 thermally insulated pipes that contain a barrier layer made of ethylene vinyl alcohol (EVOH), polyamide (PA) or polyvinylidene dichloride (PVDC). Further describes EP2340929 a plastic jacket pipe whose outer jacket is designed as a multi-layer pipe and has a gas permeation barrier layer (“barrier”) inside. The pipes described in these documents are difficult to manufacture and/or have insufficient insulation properties. Out of CH710709 (post-published) and WO2004/003423 Line pipes with thermal insulation and a polymer barrier layer are known; these polymers contain polyketones or EVOH.

Fittings and connectors are used to connect thermally insulated pipes. In particular, cover shells are used as molded parts, as in WO2008/019791 described. Or sleeves are used as connecting pieces, especially when connecting rigid pipes. The problems mentioned also arise with such molded parts and connecting pieces.

It is an object of the invention to provide a thermally insulated pipe as well as molded parts and connecting pieces which do not have the disadvantages mentioned.

The tasks outlined above are solved in accordance with the independent claims. The dependent claims represent advantageous embodiments. Further advantageous embodiments can be found in the description and the figures. The general, preferred and particularly preferred embodiments, areas, etc. given in connection with the present invention can be combined with one another as desired. Likewise, individual definitions, embodiments, etc. may be omitted or not relevant.

The present invention is described in detail below. It is to be understood that the various embodiments, preferences and ranges disclosed and described below may be combined with one another as desired. In addition, depending on the embodiment, individual definitions, preferences and ranges may not apply. Furthermore, the term “comprising” includes the meanings “containing” and “consisting of”.

The terms used in the present invention are used in the common sense familiar to those skilled in the art. Unless the direct context reveals another meaning, the following terms have the meaning/definitions given here.

• 1 zeigt schematisch den Aufbau eines erfindungsgemässen Leitungsrohrs (1) im Querschnitt. Dabei ist (2) der Aussenmantel mit Aussenseite (6) der Umgebung zugewandt und Innenseite (5) der Wärmedämmung zugewandt; (3) die Wärmedämmung mit Zellgas indiziert; (4) das Mediumrohr.
• 2 zeigt schematisch den Aufbau einer bevorzugten Ausgestaltung des Aussenmantels (2). Dabei ist (7) die äussere Polymerschicht (insbes. Thermoplast); (8) eine äussere Haftvermittlerschicht, (9) die Barriereschicht; (10) eine innere Haftvermittlerschicht und (11) die innere Polymerschicht (insbes. Thermoplast).
• 3 zeigt eine graphische Darstellung der Abhängigkeit des Wertes der Wärmeleitfähigkeit (Abszisse in der Einheit mW/m*K) eines PU-Schaums gemessen bei 50 °C in Abhängigkeit von der Zusammensetzung des Zellgases (Ordinate in der Einheit Vol %) . Die Quadrate repräsentieren Cyclopentan, die Kreise CO₂, die Dreiecke HFO.
• 4 zeigt eine graphische Darstellung der durchschnittlichen Porengrösse (Abszisse in der Einheit µm) eines PU-Schaums in Abhängigkeit von der Zellgaszusammensetzung (Ordinate in der Einheit Vol%). Die Quadrate repräsentieren Cyclopentan, die Kreise CO₂, die Dreiecke HFO.
• 5 zeigt eine graphische Darstellung der Viskosität (Abszisse in der Einheit mP*sec) eines Polyols mit verschiedenen Gehalten (Ordinate in der Einheit Gew %) von Cyclopentan bzw. HFO 1233zd. Die Quadrate repräsentieren Cyclopentan, die Dreiecke HFO.

The present invention is further illustrated by the figures; In addition to the following description, further embodiments of the invention can be found in these figures.

• 1 shows schematically the structure of a line pipe (1) according to the invention in cross section. In this case (2) the outer jacket has the outside (6) facing the environment and the inside (5) facing the thermal insulation; (3) the thermal insulation with cell gas indicated; (4) the medium pipe.
• 2 shows schematically the structure of a preferred embodiment of the outer jacket (2). Here (7) is the outer polymer layer (especially thermoplastic); (8) an outer adhesion promoter layer, (9) the barrier layer; (10) an inner adhesion promoter layer and (11) the inner polymer layer (especially thermoplastic).
• 3 shows a graphical representation of the dependence of the thermal conductivity value (abscissa in the unit mW/m*K) of a PU foam measured at 50 °C as a function of the composition of the cell gas (ordinate in the unit Vol%). The squares represent cyclopentane, the circles CO ₂ , the triangles HFO.
• 4 shows a graphical representation of the average pore size (abscissa in the unit µm) of a PU foam depending on the cell gas composition (ordinate in the unit Vol%). The squares represent cyclopentane, the circles CO ₂ , the triangles HFO.
• 5 shows a graphical representation of the viscosity (abscissa in the unit mP*sec) of a polyol with different contents (ordinate in the unit wt%) of cyclopentane or HFO 1233zd. The squares represent cyclopentane, the triangles HFO.

In a first aspect, the invention thus relates to a pipe system containing thermal insulation (also called a pre-insulated pipe system or thermally insulated pipe system), in which said thermal insulation comprises a foam whose cell gas contains hydrofluoroolefins (HFOs). Such pipe systems, but without the cell gas mentioned, are known per se and include thermally insulated pipes, sleeves and cover devices for connecting such pipes.

In a first embodiment, the invention relates to a thermally insulated line pipe (1), comprising at least one medium pipe (4), at least one thermal insulation (3) arranged around the medium pipe and at least one outer jacket (2) arranged around the thermal insulation, characterized in that that said outer jacket (2) optionally comprises a barrier (9) made of plastic, and that said thermal insulation (3) comprises a foam whose cell gas contains the components defined below.

In a second embodiment, the invention relates to a covering device made of plastic, in particular for the connection points of at least two pipe pieces which are connected there, the covering device having at least one thermal insulation (3) and at least one outer jacket (2) arranged around the thermal insulation, characterized in that that said outer jacket (2) optionally comprises a barrier made of plastic, and that said thermal insulation (3) comprises a foam whose cell gas contains the components defined below.

In a further embodiment, the invention relates to a sleeve made of plastic for connecting thermally insulated pipes, the sleeve having at least one thermal insulation (3) and at least one outer jacket (2) arranged around the thermal insulation, characterized in that said outer jacket (2 ) optionally comprises a barrier made of plastic, and that said thermal insulation (3) comprises a foam whose cell gas contains the components defined below.

This aspect of the invention will be explained in more detail below

Thermal insulation (3): The thermal insulation partially or completely encloses the medium pipe, preferably completely. Foamed plastics (“foams”) that contain a cell gas in their cells are particularly suitable for thermal insulation. The thermal insulation can be homogeneous along its cross section or made up of several layers. Typically, the thermal insulation in pipes is constructed homogeneously.

Cell gases: The gases present in thermal insulation are referred to as cell gases. These are a result of production and are made up of chemical and physical blowing agents or their reaction products. Typically, such cell gases are added during the foaming process or are formed during the foaming process.

According to the present invention, the cell gas in the foam of the thermal insulation is characterized in that it contains hydrofluoroolefins (HFOs). The cell gas can consist of just one or more HFOs and may also contain other components. The cell gas advantageously contains 10-100 vol% HFOs, preferably 20-100 vol% HFOs, more preferably 30-100 vol% HFOs, particularly preferably 40-100 vol% HFOs, very particularly preferably 50-100 vol% HFOs. Accordingly, the cell gas can contain further components.

In one embodiment, the cell gas contains 0-50 vol% (cyclo)-alkanes, preferably 0-45 vol% (cyclo)-alkanes, more preferably 0-40 vol% (cyclo)-alkanes, particularly preferably 0-35 vol% ( Cyclo)-alkanes. The ratio of HFOs to (cyclo)alkanes is preferably at least 2.5:1, preferably at least 3:1.

In a further embodiment, the cell gas additionally or alternatively contains up to 50 vol% _CO2 , preferably 0-40 vol% CO2, particularly preferably 0-30% CO2.

In a further embodiment, the cell gas additionally or alternatively contains up to 5 vol% nitrogen (N ₂ ) and/or oxygen (O ₂ ).

These additional components can be added to the blowing agent, such as the (cyclo)alkanes mentioned; they can arise during the production of the foam, such as CO ₂ ; they can get into the foam during the production process, such as air, O ₂ , N ₂ .

It has surprisingly been shown that even with such small proportions as, for example, 10 vol% HFO in the cell gas, the properties of pipe systems, in particular thermally insulated pipes, improve in a number of features.

In particular, it was found that the pipes described here have surprisingly better insulation behavior. Without feeling bound to a theory, it is assumed that the improved insulation properties are not only due to the material properties of the HFOs (thermal conductivity), but also to improved foaming caused by the changed viscosity.

In the case of PU foams and PIR foams, the addition of HFO to one of the two starting components (isocyanate or polyol) or during direct mixing in the mixing head leads to a significant reduction in viscosity. Without feeling bound to any theory, it is assumed that the reduced viscosity improves the mixing of the two components and thereby promotes the formation of comparatively smaller cells.

1. a) Zum einen würde während des Schäumprozesses eine doppelte Menge des Treibgases expandieren, was zu unkontrollierbaren Veränderungen der Schaumstruktur führte. Existierende PU-Schäume und die Produktionsanlagen sind für die geringere Menge Cyclopentan optimiert und grosse mengenmässige Veränderungen hinsichtlich des expandierenden Treibmittels hätten umfangreiche Neuentwicklungen zur Folge.
2. b) Cyclopentan wirkt als Weichmacher des PU-Schaums. Eine um das 1.86 fach erhöhte Menge führt zu dessen markanter Erweichung. Diese ist zum einen nicht gewünscht, weil der Schaum eine tragende Rolle spielt, d. h. für die mechanische Stabilität des gesamten Verbundes unabdingbar ist. Dies ist zum anderen nicht gewünscht, weil die zunehmende Weichheit des Schaums im Herstellungsprozess dazu führt, dass der gesamte Rohrverbund von der idealen runden Querschnittsgeometrie mehr und mehr abweicht. Somit wurde gefunden, dass der vollständige oder teilweise Ersatz von Cyclopentan durch HFOs die mechanischen Eigenschaften des Schaumstoffs verbessert. Üblicherweise wird dem Ausgangsmaterial Cyclopentan zugesetzt, um dessen Viskosität zu verringern; die Maximalmenge wird jedoch dadurch begrenzt, dass der erzeugte Schaumstoff ausreichende mechanische Festigkeit aufweisen muss. Durch den Ersatz von Cyclopentan durch HFOs können diese widerstrebenden Ziele erreicht werden. Der Einsatz einer vergleichbaren Menge HFO führt zu Ausgansmaterialien mit niedrigerer Viskosität bei gleichbleibender mechanischer Festigkeit des finalen Schaumstoffs. Somit kann bei gleichbleibender Produktqualität die Herstellbarkeit verbessert werden.

In order to achieve a viscosity reduction of a similar magnitude using cyclopentane as a blowing agent, its content could alternatively be increased by, for example, 1.86 times. This would be the factor by which the molecular weights of HFO 1233zd (130.5 g/mol) and cyclopentane (70.2 g/mol) differ, but this would have several disadvantageous consequences:

1. a) On the one hand, a double amount of propellant gas would expand during the foaming process, leading to uncontrollable changes in the foam structure. Existing PU foams and the production facilities are optimized for the smaller amount of cyclopentane and major changes in the quantity of the expanding blowing agent would result in extensive new developments.
2. b) Cyclopentane acts as a plasticizer of the PU foam. An amount increased by 1.86 times leads to a noticeable softening. On the one hand, this is not desirable because the foam plays a supporting role, ie it is essential for the mechanical stability of the entire composite. On the other hand, this is not desirable because the increasing softness of the foam during the manufacturing process leads to the entire pipe assembly deviating more and more from the ideal round cross-sectional geometry. Thus, total or partial replacement of cyclopentane with HFOs was found to improve the mechanical properties of the foam. Cyclopentane is usually added to the starting material to reduce its viscosity; However, the maximum amount is limited by the fact that the foam produced must have sufficient mechanical strength. Replacing cyclopentane with HFOs can achieve these counterintuitive goals. The use of a comparable amount of HFO leads to starting materials with lower viscosity while maintaining the mechanical strength of the final foam. This means that the manufacturability can be improved while maintaining product quality.

Furthermore, it was found that the addition of HFO to one of the starting components or the direct addition to the two starting components in the mixing head reduces their flammability. This effect is very advantageous because it reduces the safety requirements for such a production system and thereby significantly simplifies the design of a corresponding production system and can therefore save costs that would otherwise be incurred when working with flammable propellants.

In summary, it can be stated that the known problems can be solved in an elegant way by partially or completely replacing cyclopentane (Cp) with HFOs. On the one hand, more blowing agent can be added, which leads to a desired reduction in viscosity. At the same time, however, the expanding effect remains essentially unchanged and no fundamental adjustments to the recipe and production system are required. Ultimately, replacing the flammable cyclopentane with the non-flammable HFO improves occupational safety and reduces the investment costs for such a production system.

It was also found that high levels of (cyclo)alkanes, especially cyclopentane, have a negative influence on product quality. Experience has shown that an excessively high cyclopentane content in the polyol leads to the formation of large bubbles in the foam, which are caused by the blowing agent (especially cyclopentane) being driven out of the foam by the temperature of the PU foam that forms.

In a continuous production process, the outer jacket is usually applied by extrusion and at this point, due to the high temperature of typically 80 - 250 °C, it is in a state in which it can be easily deformed. The bubbles then become visible on the outside of the insulated pipe because the escaping propellant inflates the outer jacket. This applies equally to insulated pipes with a corrugated, a smooth and a corrugated outer jacket. The escape of the blowing agent is promoted by the temperature of the extruded outer jacket. Pipes with such defects are to be viewed as rejects and can no longer be used for their intended purpose.

The formation of bubbles is prevented if the content of cyclopentane in the cell gas composition of the resulting insulating foam is 0-50% by volume, preferably 0-45% by volume, particularly preferably 0-40% by volume, most preferably 0-35% by volume.

Surprisingly, it was found that the aforementioned bubble formation does not occur when HFO is used as a blowing agent. This applies in particular if the HFO content of the cell gas composition of the resulting insulating foam is within the limits mentioned above.

The behavior described is all the more surprising since the boiling points are 19 °C in the case of HFO 1233zd and 33 °C in the case of HFO 1336mzz. This is in comparison to cyclopentane, whose boiling point is 49 °C. Based on these boiling points, it is expected that bubble formation would be more pronounced when using the low-boiling HFO as a blowing agent than when using higher-boiling (cyclo)alkanes, e.g. Cp. The opposite was observed.

Hydroolefins (HFOs) are known and commercially available or can be produced using known methods. These are suitable as propellant gases, particularly because of their low global warming potential (GWP) and because of their harmlessness to the ozone layer of the atmosphere (Ozone Depleting Potential, ODP). The term includes both compounds that contain only carbon, hydrogen and fluorine, as well as those compounds that additionally contain chlorine (also referred to as HFCO), each containing at least one unsaturated bond in the molecule. HFOs can be present as a mixture of different components or as a pure component. HFOs can also be present as isomeric mixtures, in particular E/Z isomers, or as isomerically pure compounds.

worin R⁵ für H, F, Cl, CF₃ bevorzugt Cl, CF₃, und R⁶ für H, F, Cl, CF₃, bevorzugt H steht.HFOs which are particularly suitable in the context of the present invention are selected from the group comprising compounds of the formula (I)

where R ⁵ is H, F, Cl, CF _3, preferably Cl, CF ₃ , and R ⁶ is H, F, Cl, CF ₃ , preferably H.

Particularly suitable HFOs are R1233zd (e.g. Solstice LBA, Honeywell) and R1336mzz (e.g. Formacel 1100, Du-Pont).

It has surprisingly been shown that the line pipes described here have improved insulating behavior if the cell gases of the insulation contain at least 10% by volume, preferably at least 30% by volume, particularly preferably at least 50% by volume of HFO. It has also been shown that the addition of such HFOs to the starting materials of the foam insulation leads to improved manufacturability.

(Cyclo)-alkanes are known as cell gases for insulation in thermally insulated pipes. The said alkane or cycloalkane is advantageously selected from the group comprising propane, butanes, pentanes, cyclopentane, hexanes, cyclohexane. By combining (cyclo)alkane with HFO, the product properties can be fine-tuned and/or manufacturability can be improved and/or costs can be reduced with an acceptable loss of quality. The (cyclo)alkanes mentioned can be present as pure compounds or as mixtures; The aliphatic alkanes can be present as isomerically pure compounds or as mixtures of isomers. A particularly suitable (cyclo)alkane is cyclopentane.

Carbon Dioxide: If the foam is formed from PU or polyisocyanurate (PIR), some amount of CO ₂ is typically produced, as the raw material of technical grade polyol usually contains a small amount of water. This then reacts with the isocyanate to form carbamic acid, which spontaneously splits off _CO2 . The CO ₂ content of the cell gas is therefore linked to the purity of the starting materials and is typically below 50 vol.%. If the starting materials are water-free, for example if polyolefins are foamed, the CO ₂ content of the cell gas is 0 vol%. The CO ₂ content of the cell gas can therefore be influenced by the choice of starting materials (or their purity).

Other cell gases: Due to production, components from the atmosphere/ambient air can get into the cell gas. These are essentially N ₂ and/or O ₂ , for example air. The content of these cell gases is typically less than 5 vol.%. If the production facility is specially set up, contact with the atmosphere/ambient air can be avoided and the content of other cell gases is 0 vol%.

Foam: Said thermal insulation (3) comprises (ie contains or consists of) a foam. Such foams are known per se; foams that meet the standards DIN EN 253:2015-12 (especially for KMR) and EN15632-1:2009/A1:2014, EN15632-2:2010/A1:2014 and EN15632- are particularly suitable. 3:2010/A1:2014 (especially for PMR). The term includes rigid foams and soft foams. Foams can be closed cell or open cell, preferably closed cell, especially as set out in the standard DIN EN 253:2015-12. Such foams are preferably selected from the group of polyurethanes (PU), polyisocyanurates (PIR), thermoplastic polyesters (particularly PET), and thermoplastic polyolefins (particularly PE and PP).

• - PU enthaltend 50-100 vol% R1233zd und 0-50 vol% Cp;
• - PU enthaltend 50-100 vol% R1336mzz und 0-50 vol% Cp;
• - PIR enthaltend 50-100 vol% R1233zd und 0-50 vol% Cp;
• - PIR enthaltend 50-100 vol% R1336mzz und 0-50 vol% Cp;
• - PET enthaltend 50-100 vol% R1233zd und 0-50 vol% Cp;
• - PET enthaltend 50-100 vol% R1336mzz und 0-50 vol% Cp;
• - PE enthaltend 50-100 vol% R1233zd und 0-50 vol% Cp;
• - PE enthaltend 50-100 vol% R1336mzz und 0-50 vol% Cp.

The following combinations of foam and cell gas have been shown to be particularly beneficial:

• - PU containing 50-100 vol% R1233zd and 0-50 vol% Cp;
• - PU containing 50-100 vol% R1336mzz and 0-50 vol% Cp;
• - PIR containing 50-100 vol% R1233zd and 0-50 vol% Cp;
• - PIR containing 50-100 vol% R1336mzz and 0-50 vol% Cp;
• - PET containing 50-100 vol% R1233zd and 0-50 vol% Cp;
• - PET containing 50-100 vol% R1336mzz and 0-50 vol% Cp;
• - PE containing 50-100 vol% R1233zd and 0-50 vol% Cp;
• - PE containing 50-100 vol% R1336mzz and 0-50 vol% Cp.

In one embodiment, the cell gases mentioned add up to 100 vol%. In a further embodiment, these cellular glasses complement each other 100% together with CO ₂ and air. In a further embodiment, the ratio of HFO:Cp is at least 2.5:1.

• - PU enthaltend 50-100 vol% R1233zd und 0-50vol% Cp und 0-50 vol% CO₂;
• - PU enthaltend 50-100vol% R1336mzz und 0-50 vol% Cp und 0-50 vol% CO₂;
• - PIR enthaltend 50-100vol% R1233zd und 0-50 vol% Cp und 0-50 vol% CO₂;
• - PIR enthaltend 50-100vol% R1336mzz und 0-50 vol% Cp und 0-50 vol% CO₂
• - PU enthaltend 50-100 vol% R1233zd und 0-45vol% Cp und 10-40 vol% CO₂;
• - PU enthaltend 50-100vol% R1336mzz und 0-45 vol% Cp und 10-40 vol% CO₂;
• - PIR enthaltend 50-100vol% R1233zd und 0-45 vol% Cp und 10-40 vol% CO₂;
• - PIR enthaltend 50-100vol% R1336mzz und 0-45 vol% Cp und 10-40 vol% CO₂.

It has also been shown that the following combinations of foam and cell gas are particularly advantageous:

• - PU containing 50-100 vol% R1233zd and 0-50 vol% Cp and 0-50 vol% CO ₂ ;
• - PU containing 50-100 vol% R1336mzz and 0-50 vol% Cp and 0-50 vol% CO ₂ ;
• - PIR containing 50-100 vol% R1233zd and 0-50 vol% Cp and 0-50 vol% CO ₂ ;
• - PIR containing 50-100vol% R1336mzz and 0-50 vol% Cp and 0-50 vol% CO ₂
• - PU containing 50-100 vol% R1233zd and 0-45 vol% Cp and 10-40 vol% CO ₂ ;
• - PU containing 50-100 vol% R1336mzz and 0-45 vol% Cp and 10-40 vol% CO ₂ ;
• - PIR containing 50-100 vol% R1233zd and 0-45 vol% Cp and 10-40 vol% CO ₂ ;
• - PIR containing 50-100 vol% R1336mzz and 0-45 vol% Cp and 10-40 vol% CO ₂ .

In one embodiment, the cell gases mentioned add up to 100 vol%. In a further embodiment, these cellular glasses complement each other 100% together with air. In a further embodiment, the ratio of HFO:Cp is at least 3:1.

In a further embodiment, the thermal insulation consists of the foams mentioned and the cell gases mentioned.

Barrier (9): Diffusion barriers are known in the area of pipes/pipe systems. If there is a barrier, this barrier is designed as a layer. It is preferred that there is at least one barrier (9) as described below. It is particularly preferred that a barrier (9) is present as described below. This layer (9) enables the diffusion of cell gases out of the thermal insulation and of gases outside the pipe (in particular air) into the thermal insulation to be reduced. This property is important to ensure the insulation capability of the pipe/raw system over a longer period of time.

In an advantageous embodiment, this layer also enables the diffusion of water out of the thermal insulation. This property is particularly important for line pipes/pipe systems whose medium pipe (4) is made of plastic. If an aqueous medium is transported in such line pipes/pipe systems, water from the medium can get through the line pipe into the insulation and thus reduce the insulation capacity and damage the insulation material.

In an advantageous embodiment, this layer also allows for a certain permeability to CO ₂ . A particularly suitable value for the CO ₂ permeability is in the range of 0.5 - 100 cm ³ /m ² *day*bar. It is therefore advantageous to have a barrier with selective properties, in particular: (i) permeable to water and water vapor, (ii) impermeable to the cell gases, which have a low thermal conductivity, (iii) permeable to the cell gases, which arise during production but have a relatively high intrinsic Have thermal conductivity (e.g. CO ₂ ), (iv) impermeable to the gases from the environment, in particular nitrogen and oxygen and air.

It has been shown that a line pipe of the type mentioned at the beginning, in which the barrier comprises one or more of the polymers mentioned below, meets the requirements very well. According to the invention, the barrier can be present in a single layer or in several separate layers. Furthermore, the barrier can be attached to the insulation or the outer jacket or in the outer jacket by means of an additional layer (“adhesion promoter layer” (8), (10)).

The barrier (9) can be arranged as a layer in the outer jacket (2); this is preferred, in particular this embodiment is preferred with two adhesion promoter layers (8, 10) adjacent to the barrier (9) as in 2 explained.

Furthermore, the barrier can be arranged as a layer on the outside and/or the inside of the outer jacket. Furthermore, the barrier can be formed by the outer jacket. Furthermore, the barrier (9) can be arranged as a layer between the thermal insulation (3) and the outer jacket (2). In this embodiment, the adhesion promoter layer is typically omitted.

The barrier layer (9) advantageously has a layer thickness of 0.05 - 0.5 mm, preferably 0.1 - 0.3 mm. If the barrier forms the outer jacket, the barrier advantageously has a layer thickness of 0.5 - 5 mm. If present, the adhesion promoter layers (8, 10) independently of one another advantageously have a layer thickness of 0.02 - 0.2 mm.

The barrier preferably comprises a copolymer of ethylene with carbon monoxide or with vinyl alcohol.

worin

o

für 1 oder 2, bevorzugt 1, steht,

p

für 1 oder 2, bevorzugt 1, steht,

q

für 1-20 steht und

r

für 1-20 steht.

In an advantageous embodiment, the barrier comprises a polymer which contains polyketones or consists of polyketones. Accordingly, the polymer layer includes polyketones and blends of polyketones as well as laminates containing polyketones. Polyketones are known materials and are characterized by the keto group (C=O) in the polymer chain. In this embodiment, the polymer advantageously has 50-100% by weight, preferably 80-100% by weight, of structural units of formulas (II) or formula (III).

wherein

O

represents 1 or 2, preferably 1,

p

represents 1 or 2, preferably 1,

q

stands for 1-20 and

r

stands for 1-20.

Polyketones are available through the catalytic reaction of carbon monoxide with the corresponding alkenes, such as propene and/or ethene. Such ketones are also known as aliphatic ketones. These polymers are commercially available, for example as polyketone copolymer (formula II) or polyketone terpolymer (formula III) from Hyosung. Such polyketones are also commercially available under the trade name Akrotek® PK. Suitable polymers have a melting temperature of over 200°C (according to sen with DSC 10 K/min according to ISO11357-1/3) and/or have a low water absorption of less than 3%, measured according to DIN EN ISO 62 (saturation in water at 23 °C).

In an advantageous embodiment, the barrier comprises a polymer which contains ethyl vinyl alcohol or consists of ethyl vinyl alcohol.

worin

m

für 1-10 steht,

n

für 2-20 steht.

In this embodiment, the polymer has 50-100% by weight, preferably 80-100% by weight, of structural units of the formula (IV).

wherein

m

stands for 1-10,

n

stands for 2-20.

Suitable ethyl vinyl alcohols are, in particular, statistical copolymers in which the ratio m/n is 30/100 to 50/100. These polymers are commercially available, for example as the EVAL FP series or EP series from Kuraray. These are characterized by good processability, in particular they can be processed very well together with the normally used sheath material polyethylene (PE) by coextrusion because their melting viscosities and melting temperatures are in a similar range.

The combination of cell gases from the group of hydroolefins and barrier layers according to the formulas (II), (III), (IV) described here leads to particularly good, super-additive insulation properties of the thermally insulated pipes. Such a positive interaction between these components is surprising. Without feeling bound to a theory, this super-additive effect can be attributed to the barrier properties of the materials according to formulas (II), (III), (IV).

Medium pipe (4): In principle, all medium pipes suitable for thermally insulated pipes can be used. Accordingly, the medium pipe can be designed as a corrugated pipe, as a smooth pipe or as a pipe with a corrugated jacket; it can be a rigid and straight piece of pipe, a rigid curved piece of pipe or a flexible piece of pipe.

The medium pipe can consist of polymeric materials or metallic materials, preferably polymeric materials. Such materials are known per se and are commercially available or produced by known processes. The materials are selected by an expert based on their intended use, if necessary after routine tests.

In one embodiment, said medium pipe (4) is a flexible plastic pipe, the plastic selected from the group of acrylonitrile butadiene styrene (ABS), cross-linked polyethylene (PEXa, PEXb, PEXc), PE, polybutene (PB), polyethylene raised temperature (PE -RT), and polyketone (PK).

In a further embodiment, said medium pipe (4) is a flexible plastic pipe with an outer metal layer, the plastic selected from the group ABS, PEXa, PEXb, PEXc, PE, PB, PE-RT and PK, the metal selected from the group including aluminum its alloys. Such inner tubes are also known as composite tubes.

In a further embodiment, said medium pipe (4) is a rigid plastic pipe, the plastic selected from the group ABS, PEXa, PEXb, PEXc, PE, PB, PE-RT and PK.

In a further embodiment, said medium pipe (4) is a flexible metal pipe, the metal selected from the group of copper including its alloys, iron including its alloys (such as stainless steels), aluminum including its alloys.

In a further embodiment, said medium pipe (4) is a rigid metal pipe, the metal selected from the group of copper including its alloys, iron including its alloys (such as stainless steels), aluminum including its alloys.

In a further embodiment of the medium pipe (4), the plastic barrier already mentioned can be arranged on the outside of the inner pipe or it can be formed by the medium pipe itself. A barrier on the medium pipe, or formed by the medium pipe itself, reduces the diffusion of steam from the medium pipe into the thermal insulation. According to the invention, such a (“second”) barrier is combined with a further (“first”) barrier above the thermal insulation.

Outer jacket (2): In principle, all outer jackets suitable for thermally insulated pipes can be used. Accordingly, the outer jacket can be designed as a corrugated tube or a smooth tube or as such with a corrugated jacket. It can be a rigid and straight piece of pipe, a rigid curved piece of pipe or a flexible piece of pipe.

The outer jacket can consist of polymeric materials or metallic materials, preferably polymeric materials. Such materials are known per se and are commercially available or produced by known processes. The materials are selected by an expert based on their intended use, if necessary after routine tests. Thermoplastic polymers, such as commercial PE types, are advantageously used. High density PE (HDPE), low density PE (LDPE), linear low density PE (LLDPE) are suitable. The layer thickness of the outer jacket (2) can vary widely, but is typically 0.5 - 20 mm, including any barrier and barrier layers that may be present.

In one embodiment of the invention, the outer jacket contains the barrier described here, as described above. This configuration is advantageous because the coat and barrier can be produced simultaneously and therefore cost-effectively using coextrusion.

In an alternative embodiment of the invention, the outer jacket does not contain the barrier described here, as described above. In this embodiment, the barrier is present as a separate layer. This configuration is advantageous because the jacket and barrier can be created separately and therefore flexibly.

In an advantageous embodiment, the invention relates to a line pipe as described here, in which said outer jacket (2) is designed as a corrugated pipe; and said medium pipe is designed as a flexible piece of pipe and in particular has at least one medium pipe based on polyethylene and thermal insulation based on PU and an outer jacket based on polyethylene.

In a further advantageous embodiment, the invention relates to a line pipe as described here, in which said line pipe is a rigid, straight piece of pipe and in particular at least one medium pipe based on polyethylene or steel and a thermal insulation based on PU and an outer jacket on the base of polyethylene.

In a further advantageous embodiment, the invention relates to a line pipe as described here, in which said outer jacket (2) is designed as a corrugated pipe. Such line pipes are advantageously combined with a medium pipe, which is designed as a flexible pipe section and in particular comprises at least one medium pipe based on polyethylene or cross-linked polyethylene. Advantageously, such line pipes are also provided with thermal insulation (3) which comprises a foam whose cell gas has the above-mentioned composition (the cell gas particularly preferably containing at most 35% (cyclo)alkanes).

In a second aspect, the invention relates to methods for producing thermally insulated line pipes, sleeves and covering devices as described here. The invention is based on the object of creating improved methods for producing a line pipe, sleeve or covering device, which can be operated both continuously and discontinuously.

This aspect of the invention will be explained in more detail below.

In principle, the thermally insulated devices described here (cf. first aspect of the invention) can be produced in analogy to the known methods. The well-known ones are used Blowing agents (blowing agents, for example cyclopentane, CO ₂ ) are partially or completely replaced by the HFOs described here. Accordingly, known systems can be used for production, if necessary after adaptation to new parameters, as can be carried out by a person skilled in the art in his routine work. Those in the documents mentioned at the beginning EP0897788 and EP2213440 and EP2248648 and WO2008/019791 and EP1355103 and EP2340929 The procedures described are hereby incorporated by reference.

In an advantageous embodiment of the method, the thermal insulation (3) is formed by foaming a plastic composition which contains polymer components for foam formation and HFO as a blowing agent. According to the invention, the HFO can either be metered into one of the components and then processed or the starting components and the HFO are combined at the same time in a metering device (e.g. the mixing head).

In a further advantageous embodiment of the method, the plastic composition comprises two liquid components, the first component containing a polyol and HFO and the second component containing isocyanate. The isocyanate component is preferably one based on methylene diisocyanate. But other isocyanates such as those based on toluene 2,4-diisocyanate or aliphatic isocyanates can also be used.

In a further advantageous embodiment of the method, the plastic composition comprises two liquid components, the first component containing a polyol and the second component containing isocyanate and HFO. In particular, those HFO components are preferred which have good miscibility with the two liquid components and whose boiling point is not too low (in particular not below 10 ° C). This reduces the amount of equipment required in production; Cooling systems only need to be provided to a limited extent.

In a further advantageous embodiment of the method, the plastic composition consists of a melted component and this melt is combined with HFO under pressure.

1. (a) das mindestens eine Mediumrohr kontinuierlich zugeführt wird und mit einer zu einem Schlauch geformten Kunststofffolie umhüllt wird,
2. (b) in den Raum zwischen Mediumrohr und Schlauch eine aufschäumbarer Kunststoffzusammensetzung als Wärmedämmschicht eingebracht wird,
3. (c) das Mediumrohr und der Schlauch in ein aus mitlaufenden Formteilen gebildetes Werkzeug eingebracht werden und dieses Werkzeug an dessen Ende verlassen, und danach
4. (d) auf die Oberfläche des Schlauches der Aussenmantel extrudiert wird,

wobei die aufschäumbare Kunststoffzusammensetzung die Polymerkomponente(n) zur Schaumstoffbildung und HFO als Treibmittel enthält. In dieser Verfahrensvariante kann

• - die Barriere zwischen der aufgeschäumten Wärmedämmschicht und der Innenseite des Aussenmantels eingebracht werden, indem der Schlauch aus dem Polymer gebildet wird; oder
• - die Barriere durch Coextrusion zusammen mit dem Aussenmantel aufgebracht werden; oder
• - die Barriere direkt auf den Schlauch aufgebracht werden; oder
• - zunächst eine Schicht des Aussenmantels, gefolgt durch die Barriere und gefolgt durch mindestens eine zweite Schicht des Aussenmantels aufgebracht werden.

Variant 1: If the thermally insulated pipe of this invention comprises one or more flexible medium pipe(s) and the outer jacket (13) is a barrier made of plastic, a process variant is advantageous in which

1. (a) the at least one medium pipe is fed continuously and is covered with a plastic film formed into a tube,
2. (b) a foamable plastic composition is introduced into the space between the medium pipe and the hose as a thermal insulation layer,
3. (c) the medium pipe and the hose are inserted into a tool formed from rotating molded parts and leave this tool at the end, and then
4. (d) the outer jacket is extruded onto the surface of the hose,

wherein the foamable plastic composition contains the polymer component(s) for foam formation and HFO as a blowing agent. In this process variant you can

• - the barrier is introduced between the foamed thermal insulation layer and the inside of the outer jacket by forming the tube from the polymer; or
• - the barrier is applied by coextrusion together with the outer jacket; or
• - the barrier is applied directly to the hose; or
• - First a layer of the outer jacket is applied, followed by the barrier and followed by at least a second layer of the outer jacket.

• - kontinuierlich von einem Vorrat abgezogen werden; oder
• - kontinuierlich durch Extrusion hergestellt werden.

In this process variant, the inner tube can also be used in step a

• - are continuously deducted from a supply; or
• - produced continuously by extrusion.

1. (a) ein Mediumrohr innerhalb eines Aussenmantels zentriert wird und
2. (b) in den Raum zwischen dem Mediumrohr und dem Aussenrohr eine aufschäumbarer Kunststoffzusammensetzung als Wärmedämmschicht eingebracht wird,

dadurch gekennzeichnet, dass die aufschäumbare Kunststoffzusammensetzung die Polymerkomponenten zur Schaumstoffbildung und HFO als Treibmittel enthält. Wie bereits erwähnt, kann besagtes HFO in einem Mischkopf mit den beiden flüssigen Komponenten vermischt werden, oder besagtes HFO wird vorgänig mit einer der beiden Komponenten gemischt und dann einem Mischkopf zugeführt. In dieser Verfahrensvariante kann

• - die Barriere zwischen der aufgeschäumten Wärmedämmschicht und der Aussenseite des Aussenmantels in Form eines Schlauchs eingebracht werden; oder
• - die Barriere an der Innenseite des Aussenrohrs aufgebracht sein; oder
• - die Barriere im Aussenrohr vorgesehen sein; oder
• - die Barriere an der Aussenseite des Aussenrohrs aufgebracht sein.

Variant 2: If the thermally insulated pipe of this invention comprises one or more rigid medium pipe(s) and the outer jacket (2) with a barrier made of plastic, a process variant is advantageous in which

1. (a) a medium pipe is centered within an outer jacket and
2. (b) a foamable plastic composition is introduced into the space between the medium pipe and the outer pipe as a thermal insulation layer,

characterized in that the foamable plastic composition contains the polymer components for foam formation and HFO as a blowing agent. As already mentioned, said HFO can be mixed with the two liquid components in a mixing head, or said HFO is previously mixed with one of the two components and then fed to a mixing head. In this process variant you can

• - the barrier between the foamed thermal insulation layer and the outside of the outer jacket is introduced in the form of a hose; or
• - the barrier must be applied to the inside of the outer tube; or
• - the barrier must be provided in the outer tube; or
• - The barrier must be applied to the outside of the outer tube.

Variant 3: If the thermally insulated pipe of this invention contains thermal insulation made of a thermoplastic foam, for example made of PET, PE or PP, a process variant is advantageous in which the HFO is pressed directly into the molten polymer matrix and subsequently expanded to foam of the thermoplastic used. This can be done, for example, by melting a polymer mixture in the extruder and feeding HFO into this melt under pressure. When leaving the tool, the blowing agent present causes foaming.

In a third aspect, the invention relates to new uses of HFOs.

This aspect of the invention will be explained in more detail below.

In a first embodiment, the invention relates to the use of hydrofluoroolefins as cell gas for foam insulation in thermally insulated pipe systems, in particular in plastic medium pipe systems (PMR) and in plastic jacket pipe systems (KMR).

HFOs can advantageously be used as cell gas in foam insulation of line pipes, covering devices and sleeves, in particular line pipes, covering devices and sleeves as described here (first aspect).

The invention is explained in more detail using the following examples; these are not intended to limit the invention in any way.

Example 1: Production of a line pipe according to the invention

Medium pipes with an outside diameter of 63 mm and a wall thickness of 5.8 mm made of PExa were continuously unwound from a storage drum. Shortly before the foaming station, this medium pipe was surrounded by a PE film, which in turn was unwound from a supply and fed via a forming shoulder. The corresponding amount of a mixture of a polymeric isocyanate based on diphenylmethylene diisocyanate (MDI) with an NCO content of 31% and a polyol with an OH number of 410 mg KOH/g ( determined according to ASTMD4274D) and added with a water content of 0.8%). The isocyanate component was used slightly overstoichiometrically relative to the reactive OH groups. Before metering, the two components were mixed intensively in a high-pressure mixing head at a pressure of 150 bar. The appropriate amount of HFO / cyclopentane was previously stirred into the polyol component. Immediately after adding the two-component mixture, the tubular film was welded at the top end. The PU foam that was created immediately afterwards was forced into a cylindrical geometry by molding and after hardening, a PE jacket was continuously extruded on.

The tubes obtained were analyzed for the cell gases contained in the foam. For this purpose, small samples of around 3 cm ³ in size were punched out of the foam and these were mechanically destroyed in a closed system so that the cell gases could get into the measuring apparatus. The gases present were determined qualitatively and quantitatively in a gas chromatograph.

In addition, the thermal conductivity value at 50 °C was measured on 3 m long pipe sections in accordance with the standards DIN EN 253:2015-12 and EN ISO 8497:1996 (λ ₅₀ value). Furthermore, the composition of the cell gas (according to the Chalmers method; described in Rämnas et al, J. Cellular Plastics, 31, 375-388 , 1995); This method was also used in the examples below. The summary of the results can be found in the following table, a graphical representation is in 3 visible: Cell gas Unit No1.1 No1.2 No1.3 No1.4 No1.5 _CO2 * [Vol%] 100 51 34 31 32 Cp [Vol%] 0 46 14 9 0 HFO 1233zd [Vol%] 0 0 49 59 65 _O2 + _N2 [Vol%] 0 3 3 1 3 λ ₅₀ value [mW/m*K] 25.8 23.1 21.7 20.2 19.6
* CO2 is inevitably formed as a by-product from the starting components and is not added (chemical blowing agent).

The data clearly demonstrate the positive influence of HFO on thermal conductivity.

Example 2: Model test for foamable mixtures

An amount of 380 - 420 g of polyol was placed in a beaker and the amount of blowing agent given in the table was stirred in. The viscosity of the solution was determined in a Viscometer DV I-Prime rotational viscometer from Brookfield. The average value from three measurements was recorded.

The results are summarized in the table and in 5 represented graphically. Propellant Content of added propellant temperature viscosity [mol/100 g polyol] [K] [mPa*s] Polyol Pure polyol, without blowing agents 292.8 2005 Cp 0.043 293.2 1245 0.071 293.1 946 HFO 1233zd 0.041 293.0 1151 0.071 293.1 815

The data clearly demonstrate the positive influence of HFO on viscosity.

Example 3: Pore size in PU foams

According to DIN EN 253:2015-12 The average pore size of PU foams containing different cell gases was determined. An average of three measurements was formed.

The results are summarized in the table and in 4 graphically represented: Cell gas Unit No3.1 No3.2 No3.3 _CO2 [Vol%] 100 51 32 Cp [Vol%] 0 46 0 HFO 1233zd [Vol%] 0 0 65 _O2 + _N2 [Vol%] 0 3 3 Pore size [µm] 151.0 138.1 130.6

The data clearly shows the positive influence of HFO on cell size.

Example 4: Determination of the flash points of the starting material

According to the Pensky-Martens method ( DIN EN ISO 2719:2003-9 ), the flash points of samples No 1 and No 3 were determined. Sample No 2 was measured according to the Abel-Pensky method (DIN 51755). The same polyol was used as in Example 1. The results are summarized in the table. component Unit No4.1 No4.2 No4.3 Polyol [g/100 g polyol] 100 100 100 Cp [g/100 g polyol] 0 4.8 0 HFO 1233zd [g/100 g polyol] 0 0 8.9 Flash point normalized to 1013 mbar [°C] 102.8 < - 21 > 56

Sample No 3 has a flash point that is significantly higher than comparison sample No 2, which contains an equivamolar content of cyclopentane. In particular, sample No 3 is not classified as flammable according to Regulation EC 440/2008.

Example 5: Bubble formation depending on the blowing agent General: Thermally insulated pipes with different cell gas compositions were produced in accordance with Example 1.

Example 5.1 (comparative experiment): A quantity of cyclopentane (Cp) was metered into the polyol component using a static mixer, resulting in a content of 7% by weight based on the quantity of polyol. On the surface of the pipe produced in this way, twelve bubbles were counted over a length of 30 cm, which had a diameter of greater than 10 mm and were easy to recognize without any additional aids.

Example 5.2 An amount of 2% by weight of cyclopentane and 11% by weight of HFO 1233zd is added to the polyol. No bubbles were found on the surface of the pipe produced in this way over a length of 400 m.

Example 5.3: An amount of 15% by weight of HFO 1233zd is added to the polyol. No bubbles were found on the surface of the pipe produced in this way over a length of 350 m.

Results of Examples 5.1-5.3: The composition of the cell gases thus obtained was determined by GC as in Example 1, and the tube obtained was checked visually. E.g . Composition of cell gas control 5.1 (comparison) 69% cp 12 bubbles over 0.3m long unusable 29% CO2 0% HFO 2% H2+ N2 5.2 17% cp 0 bubbles over a 400m length without any errors 27% CO2 55% HFO 1% H2+ N2 5.3 0% cp 0 bubbles over a length of 350m without any errors 27% CO2 71% HFO 2% H2+ N2

The data show that high amounts of Cp lead to unusable insulated pipes, whereas partial or complete replacement with HFO leads to defect-free insulated pipes.

While preferred embodiments of the invention are described in the present description, it should be noted that the invention is not limited thereto and may be embodied in other ways within the scope of the following claims.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0897788 [0002, 0080]
• EP 2213440 [0002, 0080]
• EP 2248648 [0002, 0080]
• EP 1355103 [0006, 0080]
• EP 2340929 [0006, 0080]
• CH 710709 [0006]
• WO 2004003423 [0006]
• WO 2008019791 [0007, 0080]

Non-patent literature cited

• Rämnas et al, J. Cellular Plastics, 31, 375-388 [0096]
• DIN EN 253:2015-12 [0101]
• DIN EN ISO 2719:2003-9 [0104]

Claims (8)

Thermally insulated line pipe (1), comprising at least one medium pipe (4), at least one thermal insulation (3) arranged around the medium pipe and at least one outer jacket (2) arranged around the thermal insulation, characterized in that said medium pipe (4) is a flexible Pipe piece is formed, said outer jacket (2) is designed as a flexible pipe piece and optionally comprises a barrier (9) made of plastic, and said thermal insulation (3) comprises a foam containing polyurethane (PU), the cell gas of which is 50-100 vol% R1336mzz and 0 -50 vol% cyclopentane and 0-50 vol% CO ₂ , and the cell gases complement each other to 100 vol% or complement each other with air to 100 vol%. Pipe after Claim 1 , characterized in that the ratio of HFO to cyclopentane is at least 3:1. Pipe according to one of the Claims 1 or 2 , characterized in that the thermal insulation (3) consists of the foams mentioned and the cell gases mentioned. Pipe according to one of the Claims 1 until 3 , characterized in that said medium pipe (4) is a flexible plastic pipe, the plastic selected from the group ABS, PEXa, PEXb, PEXc, PE, polybutene (PB), polyethylene raised temperature (PE-RT), and polyketone (PK) . Pipe according to one of the Claims 1 until 4 , characterized in that said outer jacket (2) is designed as a corrugated tube; and said medium pipe is designed as a flexible piece of pipe. Pipe according to one of the Claims 1 until 5 , characterized in that said outer jacket (2) is designed as a corrugated tube and the outer jacket (2) is designed on the basis of polyethylene; said medium pipe is designed as a flexible piece of pipe based on polyethylene; and said thermal insulation is based on PU. Pipe system containing thermal insulation according to one of the Claims 1 - 6 . pipe system Claim 7 , selected from the group of plastic medium pipe systems (PMR).

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