WO2025248057A1

WO2025248057A1 - Non-metal pipe with filler – for improved pipe properties

Info

Publication number: WO2025248057A1
Application number: PCT/EP2025/064932
Authority: WO
Inventors: Varun SRINIVAS; Henricus Jospehus Geradus Anna GEURTS
Original assignee: Wavin BV
Current assignee: Wavin BV
Priority date: 2024-05-28
Filing date: 2025-05-28
Publication date: 2025-12-04
Anticipated expiration: 2026-11-28
Also published as: GB202407554D0

Abstract

The present invention provides a Non-Metal Pipe – For Improved Pipe Properties, specifically the present invention provides a plastic pipe comprising a polymer selected from one or more of LDPE : Low-Density PolyEthylene; HDPE: High-Density PolyEthylene; LLDPE : Linear Low-Density Polyethylene; PEX : PolyEthylene Cross linked; PP : PolyPropylene and RACO-PP : RAndom Crystalline PolyPropylene in combination with an inorganic filler this provides one or more of the benefits of low oxygen permeability, improved thermal stability, resistance to bubbling and/or blistering, shape retention on bending an improved pressure resistance.

Description

Non-Metal Pipe with Filler - For Improved Pipe Properties

Field of the Invention

The present invention relates to a pipe, such as a multi-layered pipe and to a method of manufacturing the same. In particular, the invention relates to a pipe such as a multi-layered pipe to be used for transportation of hot or cold fluids, for example use in a heating, a cooling or a water supply system.

Background to the Invention

The provision of a water supply in a building, be it either potable drinking water, hot water, water for central heating or HVAC purposes is delivered in pipes. For small buildings and offices these pipes are typically of around 20 mm diameter and in larger buildings such small pipes are present towards the end of the liquids distribution chain. Whether of larger or smaller size such pipes are typically installed manually during a building construction process, or retrofitted to an established building. As such it is more effective in the construction process if pipe can be provided in long lengths which are then bent so as to traverse a particular route within the building. Historically metal pipes have been used, such as pipes made of metal, such as copper or aluminium and steel and these can be manually bent and retain their shape. More recently there has been a move to plastics pipes for a variety of reasons, including cost and the environment. Such pipes are readily produced in very long lengths and can be transported on site in large reels unlike with metal pipes. Such pipes are resilient, that is they return to an original form after being bent and as such traverse a given route in a building by having specific joint sections added to adapt for significant changes in direction. This is relatively inefficient. Pipes may alternatively be permanently bent by means of heating, bending and cooling the pipe. This is inconvenient on site and can be irreproducible, temperatures of over 200°C, and even over 400°C typically being required. This has been one of the reasons why plastic pipe with an aluminium layer has been created. Such pipes can be bent without resilient recovery in shape. However, such pipes can be difficult to recycle as they are a plastic/metal composite.

There is therefore a need for a pipe consisting of plastics material which can be bent, such as manually without significant resilient recovery. Multi-layered plastics pipes have widely replaced single layer metal or plastic pipes, which were formerly commonly used in the building industry. By virtue of combining advantageous properties of the different layers such as e.g. rigidity, resistance against corrosion and/or efficient manufacturability, they may outperform single layer pipes.

Multi-layered pipes including a barrier layer suited to block the passage of fluids such as air or moisture have been developed. Commonly used barrier layers comprise aluminium or EVOH (ethylene vinyl alcohol). Barrier layers can protect a fluid transported in the pipe against other fluids such as from contaminations in ground in which the pipe may be located diffusing into the pipe. However, such combinations of components of widely different characteristics can hinder recycling.

A pipe with high strength and temperature resistance as well as displaying barrier properties is desirable. However, a problem encountered when attempting to manufacture a multilayered pipe displaying both strength reinforcement as well as barrier properties, e.g., by combining the aforementioned pipe including a reinforcement layer with an additional barrier layer is that inter layer bonding and mechanical properties of the pipe may deteriorate giving rise to weakness, such as delamination.

For example, it is known that vapour diffusion through the layers of a multi-layered pipe causes physical defects, which can lead to issues with pipe stability and longevity. Two types of physical defects which have been identified are blistering and bubbling. Blistering is caused by the emergence of small bubbles of gas within one or more of the individual layers of a multi-layered pipe due to vapour diffusion from the liquid that the pipe is designed to transport. Bubbling is a similar, yet more serious, condition to that of blistering, as the gas bubbles generated within a pipe wall as a result of transporting liquid through a multilayered pipe are generally bigger than those produced during blistering. A further problem is that the larger bubbles tend to emerge at the interface between two layers in a multi-layered pipe, which can cause the layers to rupture or split apart. These issues related to vapour diffusion through the layers of a multi-layered pipe can give rise to defects in the pipe itself which can lead to catastrophic failures, particularly when using pipes under pressure and/or temperature. Related to vapour diffusion, e.g. the diffusion of water as a gas, is oxygen diffusion through pipes. The provision of an oxygen barrier in plastic pipes carrying water is desirable for several reasons, primarily related to the prevention of corrosion and the maintenance of water quality. Many fluids systems, particularly water systems include metal components such as valves, pumps, boilers, and other fittings. If oxygen permeates the plastic pipes from the atmosphere and dissolves in the water, it can lead to the corrosion of those metal parts. This corrosion can cause leaks, system failures, and the need for repair or replacement. This is particularly important in hydronic heating systems, and particularly in domestic systems where the control of the components used and their compatibility may be low. In systems such as underfloor heating, the presence of oxygen can lead to the formation of rust and scale inside the pipes and other components. This can reduce the system's efficiency by lowering heat transfer rates and causing blockages. An oxygen barrier helps maintain the efficiency and reliability of the heating system. The provision of a plastic pipe with low oxygen permeability for use in hydronic systems is therefore desirable.

A further issue related to oxygen permeability is the maintaining of water quality. This is particularly relevant to potable water but also to hydronic systems. Oxygen can promote the growth of aerobic bacteria and algae water. This biological growth can degrade water quality, cause unpleasant odours and tastes, and necessitate more frequent cleaning and maintenance. It is therefore desirable to reduce oxygen permeability for the prevention of Algal and Bacterial Growth particularly in possible water systems. Again, this may be particularly valuable in domestic settings were regular testing for contamination such as Legionella may not be carried out. Another aspect is that oxygen can react with certain chemicals in the water, potentially causing unwanted chemical reactions that alter the water quality.

Associated with this is a need to stop penetration of light through plastic pipes, which even if appearing visually opaque can allow a degree of light to be transmitted through them and this may stimulate biological growth. Returning to the permeation of oxygen, it can oxidize iron and manganese, leading to discoloration and sediment formation this can lead to reduced flow and even blockage in hydronic systems and is therefore desirable to reduce oxygen permeability in the situation.

Oxygen permeability is also related to plastic pipe longevity. Some plastic materials can degrade when exposed to oxygen over long periods. An oxygen barrier helps to protect the integrity of the plastic pipes, extending their lifespan and ensuring consistent performance and is therefore desirable. Oxygen permeability, and also to some extent vapour water permeability, can be reduced by the use of opacifiers but these can interfere with other pipe properties, for example the use of nano clays. However, nano clays if entering a possible water supply can have detrimental effects as it is not desirable to ingest such materials. In summary, an oxygen barrier in plastic pipes carrying water is desirable because it prevents corrosion of metal components, maintains water quality, increases the longevity of the pipes, improves the efficiency of heating systems, and ensures compliance with industry standards. Reducing the oxygen permeability of plastic pipes is therefore desirable.

A further aspect of desirable properties for plastic pipes for liquids transfer is pressure resistance. Liquids are transferred through pipes by maintaining a preferred pressure differential between inlet and outlet. It is also desirable as it can reduce gas transport, which is relevant as mentioned above, for example regarding oxygen and water transport through a pipe wall. Further, in hydronic systems a high pressure is desirable as this not only prevents gas ingress but facilitates consistent flow through pumps, helps prevent steam formation in any boiler and improves heat transfer efficiency by ensuring maximum contact between the fluid in the pipe walls. It is therefore desirable to provide a plastic pipe which is capable of withstanding high pressures. This is particularly so in commercial installations with multistorey buildings where the static head requirement to ensure that the system is filled with water must overcome the pressure of water required to fill the highest point in the system. Further, because of the advantages of higher water pressure the typical requirements for residential systems to operate between 0.8 to 1.7 bar (80 to 170 kPa), and multi-story building systems to operate between 1.4 to 3.5 bar (140 to 350 kPa), is preferably greatly exceeded and is therefore desirable to provide a plastic pipe having a pressure resistance in excess of 7 bar (700 kPa) however this is not simple to achieve in conjunction with other desirable properties whilst maintaining a relatively low wall thickness such as may be suitable for bending.

A yet further desirable property of plastic pipes, such as for use in water supply and in hydronic systems is thermal stability. This may be evidenced in a number of ways, particularly in systems which are maintained at an elevated temperature, particularly under pressure, for an extended period of time. This deformation over time is termed creep and is evidenced by an irreversible physical deformation. Creep can lead to stress relaxation, where the internal stresses in the pipe wall decreases over time. This can compromise a pipe's ability to maintain seals at joints and connections and hence lead to leakage. Creep can also degrade the mechanical properties of pipe making it less able to withstand internal pressures and thus increase the risk of bursting or cracking over time. Similarly, creep can cause pipes to shift and misalign, disrupting the overall piping system, for example by disturbing flow. This is also found where there can be the change in pipe diameter. An increase in pipe diameter which will affect the pressure drop across the system, such as a hydronic system. Similarly sagging and deformation can create low points in the pipe network were sediment and debris can accumulate potentially obstructing and reducing system efficiency. Creep is particularly relevant to plastics used in pipes. For example, PEX (Cross-Linked Polyethylene): which has good resistance to creep at moderate temperatures but can still deform under high temperatures such as above 80°C and at pressure such as above 2 bar over long periods. CPVC has better high-temperature performance compared to some other plastics, but it can still experience creep if used near its maximum temperature rating. PP-R (Polypropylene Random Copolymer): PP-R exhibits good creep resistance, but at elevated temperatures, it too will show time-dependent deformation. It is therefore desirable to provide a plastic pipe for liquids supply, particularly in potable water or hydronic systems which is better capable of withstanding high pressure at elevated temperature for an extended period of time. This is particularly applicable to thin-walled plastic pipes plastics which are more prone to creep such as polyethylene and polypropylene which are desirable to use but may not be usable as such due to limitations in mechanical stability as evidenced by, for example, creep.

Prior art

Relevant prior disclosures include:

CN112066095 which discloses a high stiffness heat-resistant high-density polyethylene pipe comprising a main pipe body and a reinforcing pipe, the production raw material of the main pipe body is a compound heat resistant polyethylene (PE-RT) material. The use of an inorganic filler is disclosed, if the inorganic filler is talc powder and mica then of 1000-4000 mesh (25 to 5pm) size is disclosed but not whether the material is retained or passes through that mesh size. This stiff pipe is for use in large diameter wastewater piping.

WO2021165290A1 discloses a multi-layer flexible packaging material comprising a paper layer, an aluminium layer, a titanium dioxide barrier coating layer, and a sealing layer applied to the surface of the titanium dioxide barrier coating layer representing the inner surface of the multi-layer flexible packaging material, said multilayer flexible barrier material being derived of a polyolefin layer, such as a polyethylene (PE), polyethylene terephthalate (PET) or a polypropylene (PP) layer.

US2017029196A1 discloses heat sealable food packaging films, methods for the production thereof, and food packages comprising heat sealable food packaging films. The heat sealable food packaging film includes a humidity-dependent permeable film having a moisture vapor transmission rate that increases with an increase in relative humidity (RH). An outer coating comprises a coating material on at least one surface of the humidity-dependent permeable film. The coating material is selected from a titanium dioxide dispersed in a poly-vinylidene chloride (PVdC) polymer or a stretchable urethane polymer, a stretchable acrylic polymer, or a combination of stretchable urethane polymer and stretchable acrylic polymer.

DE10120620A1 discloses a multi-layered polyamide plastic pipe for conveying fluid media in heating and sanitary installations which comprises at least one layer which is constituted as a multi-material layer consisting of a polymer with embedded titanium dioxide processed as a filler element. The presence of several intermediate layers between the respective layers is required which leads to the increased risk of blistering occurring.

KR20110052265 A discloses fuel injection pipe using a nano composite to reduce fuel evaporation . The fuel injection pipe uses a nano composite comprises a nano composite. The nano composite is formed by mixing engineering plastic 97-99.7% and titanium dioxide 0.3-3% through extrusion or three-dimensional blow moulding. The engineering plastic is polyamide.

CN108178866 discloses a PE-RT pipe for use in central heating having a double-layered composite structure; an inner layer of the pipeline is type I or type II PE-RT; an outer layer of the pipeline adopts a far-infrared radiation heating composite material. The document provides no disclosure of a relevant filler for the purposes of improving bending characteristics. CN111793266 discloses a colour masterbatch, a preparation method and application thereof and a PE-RT pipe. The colour master batch is prepared from high-density polyethylene, linear low-density polyethylene, and an opacifying agent.

The various issues and desirable properties as described above can be addressed by the provision of pipes of very substantial, such as thick walled, construction, but this is inefficient. It also mitigates against ease of installation, such as by bending relevant pipes. Another approach is the use of pipes with a multilayer construction. Multilayered pipes enable materials with different properties to be combined. However, they are particularly prone to resilience recovery upon bending and therefore there is a need for a multilayer pipe consisting of plastics material which can be manually bent without significant resilient recovery. Similarly, the issue of delamination between layers, such as related to blistering and bubbling can be exacerbated as the interface between layers can be particularly susceptible to this effect as gases build up at an interface therefore the use of multilayered pipes is not necessarily the solution to the aforementioned problems. Similarly, the questions of thermal stability can be exacerbated by multilayer pipes as the coefficients of thermal expansion and contraction of different materials can give rise to a differential and a potentially very large force between adjacent layers which can increase the potential for creep and related problems.

Further, the above issues and problems can also occur in drainage systems although this is generally less of an issue due to the typical absence of elevated pressure where the transfer of gases, thermal stability and creep are typically less of an issue. Such pipes are also not usually bent as they are typically of large diameter and bending is not practicable. The threshold of pipe diameter between these types of pipes, potable/hydronic and drainage can be taken as 3 cm in diameter for practical purposes. For pipes used in domestic circumstances where manual bending is important then threshold of pipe diameter can be taken as 2.5 cm.

In the terminology of the present application a pipe consisting of plastics material is a pipe in which no layer is present where the continuous phase is other than a plastic. Hence such pipes may have additional components but in no layer do these additional components provide a continuous phase, that means it is not possible to pass from one side of the pipe to the other without encountering a plastic. In summary, the provision of an improved or alternative plastic pipe for the conveying of fluids, particularly fluids in potable water and hydronic systems, is desirable.

The Invention

The present invention in its various aspects is as set out in the appended claims.

The present invention provides: a plastics pipe the pipe comprising: at least one Carrier polymer layer comprising from 10% to 99%, preferably from 30 to 95%, of a Carrier polymer and an inorganic filler and an optional binder layer or layers comprising a binder polymer.

In the present invention the term Carrier polymer is used for clarity of reading and the term “Carrier polymer” denotes a specific composition being a polymer selected from:

LDPE : Low-Density PolyEthylene; HDPE: High-Density PolyEthylene; LLDPE : Linear Low-Density Polyethylene; PEX : PolyEthylene Cross linked; PP : PolyPropylene; PPR [PolyPropylene Random Copolymer]; PP-RCT [PolyPropylene Random Copolymer with modified Crystallinity and Temperature resistance] and RACO-PP : RAndom Crystalline PolyPropylene.

The carrier polymer is preferably selected from LDPE : Low-Density PolyEthylene; HDPE: High-Density PolyEthylene; LLDPE : Linear Low-Density Polyethylene; PEX : PolyEthylene Cross linked; and PP: PolyPropylene.

The carrier polymer is most preferably selected from LDPE : Low-Density PolyEthylene; PEX : Poly Ethylene Cross linked; and PP: PolyPropylene.

It is noted that none of the above definitions of Carrier polymer include PE-RT, either type 1 or type 2. For clarity PE-RT, and most definitely for the purposes of the present invention is not included in any of the above definitions of a Carrier polymer. Chemically the basis for this is that PE-RT has short side chains and is highly crystalline.

The “Binder layer” comprises a Binder polymer being one or more of HMWPE: high- molecular-weight polyethylene; UHMWPE: ultra-high-molecular-weight polyethylene; HMWPP: high-molecular-weight polypropylene; UHMWPP: ultra-high-molecular-weight polypropylene; and a UHMWPP/E : ultra-high molecular weight polypropylene polyethylene blend. As will be described further below the binder layer very preferably comprises a plurality of layers of a binder polymer tape, such as a tape or fibre, and is preferably a tape. The layer or layers preferably comprising of, consisting of, or preferably substantially (>98%) comprising of said binder polymer.

In the following description where more than one Carrier polymer is present this above layer is termed the first layer, it is not necessarily the innermost layer of the pipe which will be in contact with the fluid carried in the pipe but it will be concentrically within any second layer, such as a second layer comprising carrier polymer and specifically within any barrier layer. The plastics pipe of the present invention is preferably a multilayer plastics pipe.

The pipe compositions of the present invention provide a plastic pipe having one or more of low oxygen permeability, improved thermal stability, resistance to bubbling and/or blistering, shape retention on bending an improved pressure resistance.

A plastics pipe refers to a pipe made substantially of plastic of one or more types, such as a pipe wherein all the continuous phase of the solid material consists of an organic plastic. This excludes pipes which have continuous metal components, such as an aluminium layer or tube. The presence of elemental (metallic) metal components mitigates against recyclability and can reduce lifetime due to corrosion.

The plastics pipe of the present invention is preferably a plastics pipe suitable for use in plumbing, namely the system of pipes, tanks, fittings, and other apparatus required for potable water supply, heating, and sanitation in a building.

Preferably the plastic pipe of the present invention is a plastic pipe suitable for use in potable water and hydronic systems.

Preferably the plastic pipe the present invention is a plastic pipe suitable for use in a potable water system, more preferably for supplying potable water.

Preferably the plastic pipe the present invention is a plastic pipe suitable for use in a hydronic system, more preferably for heating water circulation in a hydronic system.

The invention may be suitable for use in plumbing, The pipes relevant to the present invention are primarily intended for the water supply, specifically of water, whether hot or potable and central heating (hydronic) water.

The present invention provides a plastic pipe for use in plumbing and capable of being bent manually through 90°, the pipe comprising: a) a first Carrier polymer layer comprising carrier polymer and inorganic filler forming a longitudinal axis of the pipe; the Carrier Polymer layer comprising between 5 and 60% by weight of an inorganic filler having an average particle size of particle size (D50) of from 0.5pm to 40pm.

The plastic pipe of the present invention may be suitable for being bent manually through 90° and in doing so retain its structural integrity and for subsequent suitability for use in plumbing applications. In practical terms this means capable of withstanding an operating pressure of at least 70k Pa up to 70M Pa. This may be quantified in that the pipe according to the present invention, may have a burst pressure of at least 200 Bar (2000kPa, preferably at least 600 Bar (6000kPa more preferably at least 700 Bar (7000kPa. The burst test is conducted under room temperature according to ASTM DI 599-18 standard. Preferably the pipe meets these criteria after being bent manually through 90° (as described herein). The use of the binder layers of the present invention greatly facilitates this being achieved and provides for flexibility and high pressure-resistance in a, relatively thin, layer (as defined elsewhere in this document).

This can be used to differentiate the present invention over plastic pipe which may simply be bent but fails to retain its structural integrity. Plastic pipe according to the present invention is capable of being bent and retaining its structural integrity at ambient temperature (taken as 20°C). The pipe according to the present invention has the advantage that have to having been so bent that not only does it retain its structural integrity but that the pipe retains the bend when that unrestrained. This may be quantified, as described in the method below by having less than a 25° relaxation, preferably 15°, more preferably 10° most preferably 5° relaxation of a 90° bend after 24 hours and more so after two weeks. This differentiates the present invention from other pipe-products which either require heating and cooling, such as heating to over 200°C, more typically over 400°C (which gives rise to the undesirable evolution of volatiles) before being capable of being efficiently bent manually and/or after being bent at ambient temperature provide extensive micro-cracking (often evidenced by a white coloration) which reduces the structural integrity of the pipe and/or that the pipe provides greater relaxation than that specified above such as of more than 25° relaxation of a 90° bend after 24 hours, and typically more so after two weeks. The preferred inorganic fillers for use in the present invention are Talc - Mg3Si4O10(OH)2 and/or Calcium Carbonate - CaCO3. The most preferred filler is Talc. Both these fillers reduce the resilient recovery of bent pipe enabling a bend to be maintained, such as is useful for subsequent installation of a pipe in a plumbing system. Inorganic fillers are preferred as these are inherently not resilient, inorganic fillers are preferred as they do not become admixed with the polymer in which they are present, such as when a masterbatch is prepared. Inorganic fillers of relatively high surface area are preferred, although nanoscale materials appear less effective in modifying elastic recovery with some fillers.

The pipe of the present invention may preferably further comprise, b) a Binder layer disposed around the first Carrier polymer layer.

This provides a tougher pipe, such as a pipe being less susceptible to penetration and with low gas and moisture permeability.

The pipe of the present invention may further comprise, c) a Binder layer disposed within the first Carrier Polymer layer. This provides shielding of the water supply from any solubilisable components in the Carrier polymer layer and also reduces gas permeability. The binder layer serves to give mechanical strength both in terms of pressure resistance to elongation. A suitable binder layer may be PV-OH, but this is less desirable as it may complicate recycling.

The pipe of the present invention may further comprise a, d) second Carrier polymer or PERT layer and dl) disposed outside the previously claimed layer b) or d2) inside the previously claimed layer c). This enables each Carrier polymer layer to be tailored for optimal performance. For example, one layer may be tailored to provide low gas permeability whereas another layer may be tailored to retain shape after bending. The mixing of additives into a single layer is not necessarily synergistic, whereas providing separate layers with separate functionality, such as to give an overall layer thickness equivalent to that of a single thicker layer may give a combined greater efficiency, for example in these two attributes.

In the present invention an innermost Carrier Polymer layer a) may be surrounded by Binder polymer layer b) which is turn surrounded by a Carrier Polymer layer or a PE-RT layer. In such a construction the titanium dioxide may be present in Binder polymer layer b). This can for example enable both Carrier Polymer layers a), c) to comprise filler.

In the present invention the filler present in the Carrier Polymer layer may be present an amount of up to 10 wt.% of the respective layer in which it is located. This level provides effective reduction in gas permeability, such as when the filler is present at a level from 2% to 10%. Critically, higher levels of filler may be disadvantageous in that components may leach from the layer, such as into the water supply.

In the present invention the thickness of the first Carrier Polymer layer a) may be in the range 0.5 to 7.2 mm, preferably 2 to 3mm. this provides a suitable range such that manual bending is practical. Preferably 2 to 3mm.

In the present invention the thickness of the second Carrier Polymer layer c) may be in the range 0.1 to 0.9 mm, particularly when this layer is disposed on the outer side of the pipe to the second layer the additional volume of the outer layer enables this layer to be made relatively thinner and still be effective.

In the present invention the thickness of the Binder layer b) may be in the range 0.1 to 0.7 mm. thick layers.

In the present invention the Binder layer is formed from a Binder polymer tape and that layer optionally comprises a plurality, of layers of tape with one layer on top of the other. This is more effective than co-extrusion as the difference in melting point between the Binder polymer and the Carrier polymer means that coextrusion can be problematic.

In the present invention when a Binder polymer tape is used then any two successive layers of tape may have an angle of overlap between them of from 40° to 70° degrees, this provides an effective seal and minimises the resilience of this layer in acting against the retention of a bent pipe shape.

The present invention may further comprise a bonding layer disposed between the first Carrier Polymer layer and the Binder layer, and/or a bonding layer disposed between the second Carrier Polymer layer and the Binder layer. In the present invention the pipe is preferably free from metallic aluminium or copper. The present invention is, in particular, beneficial in that it allows the removal of such conventional metals to enable pipe bending, yet with retention of bends made, for installation such as in plumbing. Plastic pipe not comprising metallic elements is also more efficiently recycled and avoids the possibility of corrosion of such metals and the ingress of such metals into the water supply.

The pipe according to the present invention may comprise layers which consist of the stated components however, the layer or layers optionally comprising minor additives at less than 5% by weight. Such additives include plasticisers, flame retardant additives, antioxidants, colourants, UV stabilisers in addition to titanium dioxide. Preferably no one such component is present at more than 2% by weight, in the weight of any given layer. Such functional components are defined as not being inorganic fillers of the present invention.

The preferred exemplification of the present invention is a first, inner, Carrier Polymer layer a) of from 95% to 30% by weight and comprising from between 5 and 60% by weight of an inorganic filler having an average particle size of particle size (D50) of from 0.5 pm to 40pm.; a Binder layer b) ; and an outer, second, Carrier polymer layer c). This provides an optimal combination of retention of shape upon bending, physical toughness and reduced gas permeability, for a pipe used in plumbing.

In a further aspect of the present invention, the invention provides a method of manufacture of a pipe as herein otherwise disclosed. The present invention therefore also encompasses a method of manufacturing a multi-layered polymer pipe, the method comprising the steps of: melt-extruding a first Carrier polymer comprising the inorganic filler containing layer a) to form a longitudinal axis of the pipe; melt-extruding a Binder layer b) over the first Carrier Polymer layer; and applying a second layer comprising Carrier polymer or PE-RT dl) over the Binder layer.

The present invention aims at providing a durable multi-layered pipe having good retention upon bending. Preferably the present invention may provide sufficient resilient flexibility that small degrees of bend, such as up to 25°, preferably up to 10°are resiliently recoverable, which allows for easier manual handling, such as an installation. The pipe of the present invention provides an adequate oxygen barrier effect by the filler containing Carrier polymer material for reducing gas transport through the layers. An important feature of the present invention is the ability for the pipe to be bent with resilient recovery at small degrees of bend such as up to 5°.

It has been surprisingly found that a multi-layered pipe having a layer comprising Carrier polymer comprising the inorganic filler material provides for reducing gas transport through the layers of the pipe. The prevention of gases diffusing from the air surrounding the pipe into the liquid medium, especially at high operating temperatures or pressures of the fluid media carried within the pipe, is considered beneficial to prolonging the lifetime of the pipe.

Preferably the inorganic filler is dispersed in at least one of the first Carrier polymer or the second Carrier Polymer layers. More preferably the inorganic filler is dispersed in the second (outer) Carrier Polymer layer. An inorganic filler containing outer layer of the multilayered pipe provides for an oxygen barrier layer immediately adjacent to the surrounding environment to maximise the reduction of potential water vapour diffusing across the layers of the multi-layered pipe which may otherwise cause blistering or bubbling.

The skilled person will appreciate that multi-layered pipes according to the present invention will vary in size according to the quantity of fluid they are designed to transport or the type of dwelling they are intended for use in, but will preferably have an outer pipe diameter in the range from 8 mm to 200 mm, or from 10 mm to 110 mm , preferably 10 mm to 90 mm, more preferably in the range from 16 mm to 75 mm. The overall outer wall thickness comprising the various layers of the multi-layered pipes is therefore preferably in the range from 1.5 mm to 9 mm, more preferably 2 mm to 7.5 mm, which is suitable for potable water supply and hydronic systems.

Preferably, the thickness of the first Carrier Polymer layer a) is at least 0.5 mm, preferably at least 0.6 mm, preferably at least 0.7 mm, preferably at least 0.8 mm, preferably at least 0.9 mm, preferably at least 1.0 mm, preferably at least 1.1 mm, preferably at least 1.2 mm, preferably at least 1.3 mm, preferably at least 1.4 mm, preferably at least 1.5 mm, preferably at least 1.6 mm, preferably at least 1.7 mm, preferably at least 1.8 mm, preferably at least 1.9 mm, preferably at least 2.0 mm, preferably at least 2.1 mm, preferably at least 2.2 mm, preferably at least 2.3 mm, preferably at least 2.4 mm or preferably at least 2.5 mm. Preferably, the thickness of the first Carrier Polymer layer a) is at most 0.6 mm, preferably at most 0.7 mm, preferably at most 0.8 mm, preferably at most 0.9 mm, preferably at most 1.0 mm, preferably at most 1.1 mm, preferably at most 1.2 mm, preferably at most 1.3 mm, preferably at most 1.4 mm, preferably at most 1.5 mm, preferably at most 1.6 mm, preferably at most 1.7 mm, preferably at most 1.8 mm, preferably at most 1.9 mm, preferably at most 2.0 mm, preferably at most 2.1 mm, preferably at most 2.2 mm, preferably at most 2.3 mm, preferably at most 2.4 mm or preferably at most 2.5 Preferably the thickness of the first Carrier polymer layer is at most 3.5 mm, preferably at most 4.5 mm, preferably at most 5.5 mm, preferably at most 6.5 mm, preferably at most 7.0 mm, preferably at most 7.1 mm, preferably at most 7.2 mm, preferably at most 7.3 mm, preferably at most 7.4 mm, preferably at most 7.5 mm, preferably at most 7.6 mm, preferably at most 7.7 mm, preferably at most 7.8 mm, preferably at most 7.9 mm, preferably at most 8.0 mm, preferably at most 8.1 mm, preferably at most 8.2 mm, preferably at most 8.3 mm, preferably at most 8.4 mm or preferably at most 8.5 mm. the above at least and that most figures are intended to be combined to provide potential ranges of carrier on the layer thickness; the at least thickness always being lower than the utmost thickness. Preferably the thickness of the first Carrier polymer layer is in the range 1.3 mm to 7.2 mm. This is good because the first Carrier Polymer layer, the inner layer of pipe, is made as thick as possible in order to allow for the outer layer (the second Carrier polymer or PE-RT layer c)) of the multi-layered pipe to be as thin as possible. Also, it is preferred that a thinner outer layer helps with compatibility with certain exterior fittings.

Preferably, the thickness of the second Carrier Polymer layer c) is at least 0.1 mm, preferably at least 0.2 mm, preferably at least 0.3 mm, preferably at least 0.4 mm, preferably at least 0.5 mm, preferably at least 0.6 mm, preferably at least 0.7 mm or preferably at least 0.8 mm. Preferably the thickness of the second Carrier polymer or PE-RT layer is at most 0.5 mm, preferably at most 0.6 mm, preferably at most 0.7 mm, preferably at most 0.8 mm, preferably at most 0.9 mm, preferably at most 1.0 mm, preferably at most 1.1 mm, preferably at most 1.2 mm, preferably at most 1.3 mm, preferably at most 1.4 mm or preferably at most 1.5 mm. Preferably the thickness of the second Carrier Polymer layer is in the range 0.1 mm to 0.9 mm. The thickness of the second Carrier Polymer layer, which may alternatively comprise PE-RT, is selected to be as thin as possible so that in scenarios where the inorganic filler is present in the first and second layers this layer, it is easier for the second Carrier Polymer layer (outer) to be compatible with certain exterior fittings.

Preferably, the thickness of the Binder layer b) is at least 0.1 mm, preferably at least 0.2 mm, preferably at least 0.3 mm, preferably at least 0.4 mm or preferably at least 0.5 mm.

Preferably the thickness of the Binder layer is at most 0.5 mm, preferably at most 0.6 mm, preferably at most 0.7 mm, preferably at most 0.8 mm, preferably at most 0.9 mm, preferably at most 1.0 mm, preferably at most 1.1 mm, preferably at most 1.2 mm, preferably at most 1.3 mm, preferably at most 1.4 mm or preferably at most 1.5 mm. Preferably the thickness of the Binder layer is in the range 0.1 mm to 0.7 mm. The thickness may arise from a plurality of individual layers to form an aggregated layer defined as a plurality of layers between adjacent layers of other polymer composition. The thickness may be measured using a micrometre or other mechanical measuring tool.

That plurality may be 2 or more layers or more layers, preferably from 2 to 15, layers, more preferably from 3 to 12 layers, most preferably from 3 to 6 layers.

Preferably the Binder layer comprises a Binder polymer tape or a fibre. A Binder layer comprising a Binder polymer tape or a fibre provides for a thicker reinforcing layer of the multi-layered pipe.

Preferably the Binder polymer tape layer comprises said plurality of layers of tape with one layer on top of the other. In this manner, the Binder layer is formed from several layers of Binder polymer tape which increases the strength of the Binder polymer tape while maintaining the overall flexibility of the Binder polymer tape layer itself, as well as that of the multi-layered pipe.

The Binder polymer layer when in the form of tape is preferably wound upon the Carrier polymer layer.

The present invention therefore also encompasses a method of manufacturing a multi-layered polymer pipe, the method comprising the steps of: melt-extruding a first Carrier polymer comprising the inorganic filler containing layer a) to form a longitudinal axis of the pipe; winding one or more layers of a Binder layer b) over the first Carrier Polymer layer; and optionally applying a second layer comprising Carrier polymer or PE-RT layer c) over the Binder layer. The Binder layer tape is preferably wound so as to continuously overlap itself , or additionally or alternatively the tape is preferably wound so that a subsequent and abutting layer continuously overlaps a preceding layer. This is found is to give improved strength as a defined point of weakness, the edge of the tape is reinforced by the overlap. This is more consistent than a continuous layer not being formed of the tape is for a given average thickness any inevitable weak point in a continuous layer, typically of unknown location, is avoided by creating a defined point of weakness which is then reinforced.

Preferably one or more of the plurality of layers of tape has an angle of winding compared to the normal of the principal axis of the pipe of at least 20° degrees, preferably at least 25° degrees, preferably at least 30° degrees, preferably at least 35° degrees, preferably at least 40° degrees, preferably at least 45° degrees, preferably at least 50° degrees or preferably at least 55° degrees. Preferably one or more of the layers of tape have an angle of winding between them of at most 60° degrees, preferably at most 65° degrees, preferably at most 70° degrees, preferably at most 75° degrees, preferably at most 80° degrees, preferably at most 85° degrees or preferably at most 90° degrees. Preferably the two layers of tape have an angle of winding between them of from 40° to 70° degrees. For the avoidance of doubt the angle may represent clockwise or anticlockwise winding and when the alternative direction of winding is used then the preferred ranges remain and if desired can be considered to be the negative of the angle in the alternative rotation but this is not considered geometrically necessary.

Adjacent layers being wound in different rotations can be considered to have the same angle of winding.

It has been found that when the two layers of tape have an angle of winding between them in this range then this maximises the strength and flexibility of the Binder polymer tape layer. In particular it is been found that if no two adjacent layers have the same angle of winding, then this provides improved strength for a bent pipe. This is because as any particular angle of bending does not give rise to a particular weakness as each angle of winding in itself as a particular angle between zero and 90° of bending at wish it is the weakest, this compensates for the unknown angle of bending in use which is subsequent to manufacture and dependent upon a given installation

The winding of the binding layer in the form of a tape may be all in the same rotation, such as clockwise or anticlockwise compared to the principal the principal axis of the pipe is defined by the longest implicitly lengthwise axis, such as defined by any notional centre point of a cross-section of the pipe. The normal to this is a normal i.e. at 90° such as a plane at 90° to the principal axis of the pipe.

Preferably winding of abutting layers of tape forming the binding layers in any given binding layer of the pipe are alternating in rotation. This reduces weaknesses forms on pipe bending Preferably the multi-layered pipe further comprise a bonding layer disposed between the first Carrier Polymer layer and the Binder layer, and/or a bonding layer disposed between the second Carrier Polymer layer and the Binder layer. While not an essential requirement to the present invention, additional bonding layers, whether present between the first Carrier Polymer layer and the Binder layer, and/or between the second Carrier Polymer layer and the Binder layer allow the corresponding first or second Carrier polymer layer(s) and the Binder layer to more strongly adhere to each other to minimise seam openings between the layers which may be exploited by blistering or bubbling phenomena, may be present.

Preferably any bonding layer is formed from high density polyethylene (HOPE), HDPE grafted with maleic anhydride (HDPE-g-MA), low density polyethylene (LDPE), LDPE grafted with maleic anhydride (LDPE-g-MA) or combinations thereof. Bonding layers formed from HDPE or LDPE, whether grafted with maleic anhydride (such as representing from 10 to 20% of polymer repeat units) otherwise, provide for improved bonding between successive layers of the first Carrier Polymer layer and the Binder layer, or the second Carrier Polymer layer and the Binder layer.

Preferably, the thickness of any, at least one, bonding layer is at least 0.1 mm, preferably at least 0.2 mm, preferably at least 0.3 mm, preferably at least 0.4 mm, preferably at least 0.5 mm, preferably at least 0.6 mm, preferably at least 0.7 mm or preferably at least 0.8 mm. Preferably the thickness of the second Carrier polymer or PE-RT layer is at most 0.5 mm, preferably at most 0.6 mm, preferably at most 0.7 mm, preferably at most 0.8 mm, preferably at most 0.9 mm, preferably at most 1.0 mm, preferably at most 1.1 mm, preferably at most 1.2 mm, preferably at most 1.3 mm, preferably at most 1.4 mm or preferably at most 1.5 mm. Preferably the thickness of the at least one bonding layer is in the range 0.1 to 0.9 mm. More preferably the thickness of the at least one bonding layer is in the range 0.2 mm to 0.6 mm. The thickness of the at least one bonding layer is selected so as to not be too thick, otherwise it affects the long-term performance of the multi-layered pipe. For example, when the at least one bonding layer is an LDPE-based bonding layer it has a lower melting point compared with layers comprised of Carrier polymer, PE-RT or UHMWPE. In general, the thickness of the at least one bonding layer is at most 10% of the overall pipe diameter.

Preferably the at least one bonding layer is free from ethylene vinyl alcohol (EVOH). EVOH is known to be a strong barrier against oxygen and gas, it is difficult to make and therefore more expensive. The use of EVOH also provides disadvantages in terms of recyclability, and the fact that when it is used additional tie layers are required in order to bond various layers of the pipe together.

Preferably the multi-layered pipe is free from aluminium. A polymeric multi-layered pipe that does not comprise aluminium maintains good flexibility and can therefore be used in a variety of scenarios where flexibility is useful, e.g. to transport liquids around corners without the use of separate pipe joints.

Preferably the multi-layered pipe has a density of less than 1.5 g/cm³ , more preferably less than 1.0 g/cm³. This is good because it is cheaper and easier to transport than conventional metal or PVC alternatives.

Accordingly, the invention provides for a multi-layered pipe for conveying hot fluid such as water in a dwelling, the pipe consisting of concentric layers of polymeric material, the layers being: an, optional, innermost PE-RT layer the first, inner Carrier Polymer layer; a); a Binder layer b); and an outer second Carrier polymer or PE-RT layer, c).

The multi-layered pipe of the present invention in this form provides for an oxygen barrier layer immediately adjacent to the surrounding environment.

The multilayered pipe in the present invention provides improved pressure resistance.

The multilayered pipe of the present invention provides improved stability thermal stability. The multilayered pipe of the present invention provides improved stability thermal stability improved dependability, such as meant manual bend ability and shape retention upon bending. Alternatively, the invention provides for a multi-layered pipe for conveying hot water in a dwelling, the pipe consisting of concentric layers of polymeric material, the layers being: an, optional, innermost PE-RT layer a first, inner, Carrier Polymer layer a); a Binder layer comprising d); and an outer second or PE-RT layer c).

Alternatively, the invention provides for a multi-layered pipe for conveying hot water in a dwelling, the pipe consisting of concentric layers of polymeric material, the layers being: an, optional, innermost PE-RT layer a first, inner, Carrier polymer layer; a); a first LDPE bonding layer comprising a titanium dioxide material d); a Binder layer b); a second LDPE bonding layer comprising a titanium dioxide material d2); and an outer second Carrier polymer or PE-RT layer c).

In this embodiment, at least one Carrier Polymer layer is located between an interior flow path of the multi-layered pipe and the Binder layer in order to maximise the reduction of potential water vapour diffusing across the layers of the multi-layered pipe which may otherwise cause blistering or bubbling. Bonding layers formed from HDPE or LDPE, whether grafted with maleic anhydride or otherwise, provide for improved bonding between successive layers of the first Carrier Polymer layer and the Binder layer, or the second Carrier polymer or PE-RT layer and the Binder layer.

Alternatively, the invention provides for a multi-layered pipe for conveying hot water in a dwelling, the pipe consisting of concentric layers of polymeric material, the layers being: an, optional, innermost PE-RT layer; a first, inner, Carrier Polymer layer; a); a LDPE bonding layer d); a Binder layer b); and an outer second Carrier polymer or PE-RT layer comprising inorganic filler c). This is good because thermal stability is increased in the Binder layer. This improvement is improved by the presence of determining dioxide when present in the UHMWPE polymer layer, resulting in better wear resistance. In addition, at least one Carrier Polymer layer is located between an interior flow path of the multi-layered pipe and the Binder layer in order to maximise the reduction of potential water vapour diffusing across the layers of the multilayered pipe which may otherwise cause blistering or bubbling. Bonding layers formed from HDPE or LDPE, whether grafted with maleic anhydride or otherwise, provide for improved bonding between successive layers of the first Carrier Polymer layer and the Binder layer, or the second Carrier polymer or PE-RT layer and the Binder layer.

Preferably, a portion of the Binder layer may be dispersed in at least one of the first or second Carrier Polymer layers. In scenarios when the Binder layer comprises a Binder, preferably the Binder polymer fibres are dispersed in at least one of the first or second Carrier Polymer layers to form a matrix. The skilled person will appreciate that in scenarios when a portion of the Binder layer may be dispersed in at least one of the first or second Carrier Polymer layers, talcum may still be dispersed in at least one of the first or second Carrier polymer layers or dispersed in the binder layer in accordance with a first embodiment of the invention. In this manner, at least one of the first or second Carrier Polymer layers of the multi-layered pipe may therefore further comprise a mixture of Binder polymer tapes or fibres and optionally to turning dioxide.

Accordingly, a second embodiment of the invention relates to a method of manufacturing a multi-layered polymer pipe according to any preceding claim, the method comprising the steps of: melt-extruding a first Carrier Polymer layer to form a longitudinal axis of the pipe; melt-extruding a Binder layer b) over the first Carrier Polymer layer a); and applying a second Carrier Polymer layer c) over the UHMWPE layer.

Such a method is considered to be cheaper and easier to carry out in order to manufacture a multi-layered pipe according to a first embodiment of the present invention because i) fewer layers are required to form the multi-layered pipe, ii) those that are required can easily bonded and adhere together due to the similar chemical nature of the individual layers, and iii) the entire process can be carried out using existing technology. Preferably the method of manufacturing a multi-layered polymer pipe comprises the additional steps of: applying a bonding layer over the first Carrier Polymer layer prior to melt-extruding the Binder layer; and/or applying a bonding layer over the Binder layer prior to applying the second Carrier polymer or PE-RT layer.

The incorporation of one or more additional bonding layers improves the bonding between the existing layers of the multi-layered pipe, to increase the overall strength and flexibility of the multi-layered pipe while simultaneously maximising the reduction of potential water vapour diffusing across the layers of the multi-layered pipe.

The Carrier polymer is resilient and allows considerable elastic deformation. In some uses it is desirable that the multi-layered polymer pipe of the present invention is deformable, such as in bending, a typical requirement in applications, but it does not show significant resilient recovery upon bending. The resilience of the multi-layered pipe of the present invention is therefore preferably reduced. Reduction of resilience may be conveniently achieved by the use of fillers, which can be termed bulk fillers. However, the use of titanium dioxide (a functional filler) and its beneficial effects, as described above, can be adversely affected by the introduction of other fillers, by a filler is meant a physical particulate in addition to the polymer. It is therefore preferable to limit the resilience (elastic recovery) of the multilayered pipe of the present invention without providing additional solids materials to the Binder layer. It has been found that the desired characteristics can be achieved by adding a filler to the Carrier polymer or PE-RT composition, of which at least one layer must comprise said filler and Carrier polymer. However, it has been found that not all fillers are suitable and certainly not as equally effective.

An inorganic filler in the present invention, is of particle size (D50) lOnm or greater and preferably less than 40pm; or of particle size (D50) lOOnm (0.1pm) or greater and preferably less than 10pm; more preferably in the range particle size (D50) lOOnm (0.1 pm) or greater and preferably less than 4pm; most preferably in the range particle size (D50) lOOnm (0.1pm) or greater and preferably less than 1pm. Larger particles at higher filler levels lead to weaker polymer composite. The smaller particles, particularly those less than 1pm or understood, perhaps because of high surface area, to contribute particularly to the improved effect of retention of deformation on pipe bending and the additional effects of reduced oxygen transport thermal stability and pressure resistance.

In the present invention inorganic fillers are preferred as any dissolution into the water supply, such as for potable water has intrinsically lower toxicity and thermal stability is intrinsically higher particularly given that low levels of decomposition at elevated temperature over time can reduce the structural integrity of a pipe or increase the release of potential toxins into water. A preferred method for measuring particle size is ISO 19749:2021(en).

Preferred inorganic fillers suitable for inclusion in the Carrier Polymer layer(s) of the present invention (which are of the defined particle size) include:

Talc - Mg3Si4O10(OH)2; Calcium Carbonate - CaCO3, such as in the form of chalk ; Kaolinite - A12Si2O5(OH)4; Wollastonite - CaSiOa; Mica muscovite - KA12(Si3A10io)(OH)2; Mica phlogopite - KMg3(AlSi3Ow)(OH)2; Glass beads or fibre - SiO2; Calcium Silicate - Ca₂SiO₄, such as diatomaceous earth and Barium sulphate - BaSO4

The preferred inorganic fillers are Talc - Mg3Si4O10(OH)2 and Calcium Carbonate - CaCO3 such as in the form of chalk.

The most preferred filler is Talc as this provides the greatest reduction in resilient recovery of a bent pipe in a pipe comprising a PE/RT layer utilising this filler. The Talc is preferably within one or more of the aforementioned D50 particle size ranges.

Talc of Type B or C ISO standard for quality (ISO 3262) is preferred, Type D having high loss on ignition provides a weaker polymer compound.

Talc is widely available filler material however it is not readily available (D50) particle sizes below 1pm. a preferred source of talc is Nanoshel NS6130-02-289 having a particle size of (D50) lOOnm (0.1pm) . Talc with a particle size less than 1pm is termed herein as nanotalc.

In the present invention a filler may be included at a level of between 5 and 60% by weight in the first (inner) Carrier Polymer layer a). The first Carrier polymer layer of the present invention may therefore comprise between 95 and 40% of Carrier polymer. A preferred level of inorganic filler inclusion for reduction in resilient recovery of a bent pipe is between 10 and 45% by filler inclusion weight in the polymer in conjunction with between 90 and 55% Carrier polymer. Higher levels of inorganic filler inclusion can show a reduction in pipe strength, a more preferred filled inclusion is 20 to 40% such as in the polymer in conjunction with between 80 and 60% Carrier polymer.

Additionally, a filler may be included at a level of between 10 and 60% by weight in a second Carrier Polymer layer disposed around the Binder layer. This has been shown to provide yet further improve pipe bending and lack of resilient recovery when bent beyond 45°.

The filler may be used in both of the Carrier Polymer layers.

However, a filler incorporated into the Carrier polymer as an innermost layer can potentially come into contact with water in the pipes such as potable water. It can be preferable to have the filler in the a (first) Carrier polymer layer as the first layer surrounding any innermost Carrier polymer layer or PE-RT layer so as to enable a low level of filler to be used or to be absent in the innermost layer. For clarity, the first Carrier layer is as described herein, but this layer, even if described as a first layer, may not be the innermost layer of pipe as an innermost layer may additionally be present so as to present a plastic to carried fluid, such as possible water, which does not leach materials into the fluid. The innermost layer may be any of the polymers suitable as a carrier polymer and here also includes PE-RT. Nevertheless, the first, Carrier layer may be the innermost layer and, if acceptable for fluid/water quality purposes, this is preferable.

In terms of the desirable characteristic of a pipe of the invention retaining its deformation after bending (longitudinal bending) it has been found that incorporating the filler in the first (inner) Carrier Polymer layer is the more effective. Incorporating the filler in the second (outer) is also effective in reducing resilient recovery after pipe bending, but less so.

When the nano-talc incorporated in the Carrier Polymer layer it is preferably incorporated in the inner later for reducing gas transport, as moisture, from the contents of the pipe. The presence of filler (i.e. bulk filler with the nano clay is disadvantageous as it increases the gas permeability, the bulk filler is therefore preferably in another Carrier polymer or PE-RT layer c). The bulk filler is therefore preferably provided in the outer Carrier polymer or PE-RT layer. The plastic pipe of the present invention, as herein described, is preferably configured for use with a hot water supply (such as operating at 30 to 80°C) and therefore capable of withstanding a pressure of more than Ibar, such as in the range 1 to 8 bar in that temperature range. The pipe of the present invention is preferably, normal to longitudinal in the axis of the pipe circular in cross-section, i.e. when on bent the pipe is cylindrical. This provides maximum strength, the lowest deformation for any given internal pressure and uniformity of bending characteristics in any particular direction relative to the principal axis, i.e. the length, of the pipe- The aforementioned tax the phrase Carrier polymer or PE-RT layer is used, this denotes a layer comprising the aforementioned county carrier polymer is or is a further alternative PERT. The PE-RT maybe type I or type II. Type II which is cross-linked is preferred .

BRIEF DESCRIPTION OF THE DRAWINGS

The description is given with reference to the accompanying drawings where like numerals are intended to refer to like parts and in which:

Figure 1 represents a cross-sectional view of a multi-layered pipe according to a first embodiment of the invention;

Figure 2 represents a cross-sectional view of a multi-layered pipe according to an alternative first embodiment of the invention;

Figure 3 represents a cross-sectional view of a multi-layered pipe according to an alternative first embodiment of the invention;

Figure 4 represents a cross-sectional view of a multi-layered pipe according to an alternative first embodiment of the invention;

Figure 5 shows a tool and process for pipe bending, such as used in the test method; and Figure 6 shows the methodology for measuring pipe bend relaxation over time as used in the test method.

The following abbreviations have been used extensively throughout the description.

Abbreviations

PE-RT: PolyEthylene of Raised Temperature resistance; this is characterised by short side chains on the PE main chain and high crystallinity.

PE-RT type I: as PE-RT but with a low degree of cross-linking as evidenced by displaying a gel content in the range 10 to 30% as measured using ISO 22391 or ASTM F2769.

PE-RT type II: as PE-RT but with a high degree of cross-linking as evidenced by displaying a gel content in the range 31 to 70% as measured using ISO 22391 or ASTM F2769.

LDPE : Low-Density PolyEthylene a highly branched structure and has low crystallinity. HDPE: High-Density PolyEthylene; this can be considered as an un branched structure. LLDPE Linear Low-Density Polyethylene.

PEX : PolyEthylene Cross linked

PP : PolyPropylene

PPR : [PolyPropylene Random Copolymer] PP-RCT : [PolyPropylene Random Copolymer with modified Crystallinity and Temperature resistance]

RACO-PP : RAndom Crystalline PolyPropylene

Linear polymer with significant short-chain branching.

LDPE: low-density polyethylene;

HMWPE: high-molecular-weight polyethylene;

UHMWPE: ultra-high-molecular-weight polyethylene;

HMWPP: high-molecular-weight polypropylene;

UHMWPP: ultra-high-molecular-weight polypropylene;

UHMWPP/E : ultra-high molecular weight polypropylene polyethylene blend (HDZLD)PE-g-MA: (high-density/low-density) polyethylene-graft-maleic anhydride.

For the avoidance of any doubt, a corresponding definition of each of the acronyms used is provided below.

Definitions

PE-RT is a polyethylene (PE) resin in which the molecular architecture has been designed such that a sufficient number of tie chains are incorporated to allow operation at elevated or raised temperatures (RT). Tie chains "tie" together the crystalline structures in the polymer, resulting in improved properties such as elevated temperature strength and performance, chemical resistance and resistance to slow crack growth. Suitable grades of PE-RT include > Dowlex 2388, Dowlex 2344, Dowlex 2355 and Dowex 2377 ex Dow; Hostalen 473 IB ex Hostalen 413 IB ex. Lyondell-Basell; Daelim XP 9020 ex Daelim; Hanwha M7037 ex Hanwha; Lucene SP 988 ex LG Chem and Yuclair DX800 ex SKC.

HDPE or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. HDPE is known for its high strength-to-density ratio. HDPE pipe does not rust, rot or corrode, and is resistant to biological growth. This means an extended service life and long-term cost savings. The density of HDPE ranges from 0.93 to 0.97 g/cm³. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder, more opaque, and can withstand somewhat higher temperatures (120 °C/248 °F for short periods). High- density polyethylene, unlike polypropylene, cannot withstand normally required autoclaving conditions. The lack of branching is ensured by an appropriate choice of catalyst (e.g. Ziegler-Natta catalysts) and reaction conditions. HDPE is resistant to many different solvents, so it cannot be glued, pipe joints must be made by welding, but this makes pipes constructed out of HDPE ideally suited for transporting drinking water and waste water (storm and sewage).

LDPE is a thermoplastic also made from the monomer ethylene. LDPE is defined by a density range of 0.917 to 0.93 g/cm³. At room temperature it is not reactive, except to strong oxidizers; some solvents cause it to swell. It can withstand temperatures of 65 °C (149 °F) continuously and 90 °C (194 °F) for a short time. Made in translucent and opaque variations, it is quite flexible and tough. LDPE has more branching (on about 2% of the carbon atoms) than HDPE, so its intermolecular forces (instantaneous-dipole induced-dipole attraction) are weaker, its tensile strength is lower, and its resilience is higher The side branches mean that its molecules are less tightly packed and less crystalline, and therefore its density is lower. When exposed to consistent sunlight, the plastic produces significant amounts of two greenhouse gases: methane and ethylene. Because of its lower density (high branching), it breaks down more easily than other plastics; as this happens, the surface area increases.

Production of these trace gases from virgin plastics increases with surface area and with time, so that LDPE emits greenhouse gases at a more unsustainable rate than other plastics. When incubated in air, LDPE emits methane and ethylene at rates about 2 times and about 76 times, respectively, more than in water.

A UHMWPE is a polyethylene polymer that comprises primarily ethylene-derived units and in some embodiments, the UHMWPE is a homopolymer of ethylene. Optionally, a UHMWPE may comprise additional a-olefins such as, but not limited to, 1-butene, 1- pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl- 1- pentene, and 3-methyl- 1- pentene. A suitable UHMWPE may have a weight average molecular weight (Mw) of about 1,500,000 g/mol or greater, about 1,750,000 g/mol or greater, about 1,850,000 g/mol or greater, or about 1,900,000 g/mol or greater. These molecules are several orders of magnitude longer than those of familiar HDPE due to a synthesis process based on metallocene catalysts, resulting in UHMWPE molecules typically having 100,000 to 250,000 monomer units per molecule each compared to HDPE's 700 to 1,800 monomers. Examples of commercially available UHMWPE include MIPLEON™ XM-220, MIPLEON™ XM-330 (both available from Mitsui Chemical), Ticona GUR™ 4170 (available from Celanese, Dallas, TX, USA), UTEC3040 (Braskem), LUBMER™ 5000 and LUBMER™ 5220 (both available from Mitsui Chemical).

Suitable UHMWPE may be in a powder or pellet form and/or have an average particle diameter of about 75 pm or less, about 70 pm or less, or about 65 pm or less. Additionally, or alternatively, suitable UHMWPE may have an average particle diameter of 10 pm or greater, 15 pm or greater, 20 pm or greater, or 25 pm greater. Additionally, or alternatively, suitable UHMWPE may have an average particle diameter of about 40 pm to about 75 pm, such as about 50 pm to about 70 pm, or about 55 pm to 65 pm. Additionally, or alternatively, suitable UHMWPE may have an average particle diameter of about 10 pm to about 50 pm, such as about 15 pm to about 45 pm, about 20 pm to about 40 pm, or about 25 pm to about 30 pm.

Particle size in the present invention is determined by ASTM E2834-12(2022) suitable equipment is the NanoSight NS300 from Malvern Panalytical (R). This is suitable for the nano clay. For larger particles than the nano scale, such as the bulk filler, particle size may be determined using a Mastersizer 3000 Malvern Panalytical (R).

Water may be used as the medium for suspending the solid in analysis. Measurement are made at 25°C unless the method requires otherwise. The preferred particle size measurement is D3,2 unless the method requires otherwise. Plastics particle size may be measured using ASTM D7486-14.

Binder polymer tape is available from a range of manufacturers including 3M, CS Hyde Company, and TapeCase. The tape is preferably of thickness between 0.01 and0.5mm, more preferably of thickness between 0.05mm and 0.15mm. required thickness of a Binder polymer tape layers of the present invention is typically achieved by utilising a plurality of laminated Binder polymer tape layers.

PE-g-MA, structure reproduced below for reference, is a compatibilizer for polymer blends which serves as support for polar to nonpolar substances:

PE-g-MA

It is known that PE-g-MA introduced or admixed with LDPE/HDPE results in blends which have higher thermal stability. This is a desirable property for the formation of multi-layered pipes.

DETAILED DESCRIPTION OF THE INVENTION

Pipe bending method and test.

This is illustrated in conjunction with figures 5 and 6.

The present invention utilises a method for determining the retention of a bend in the pipe created by manual bending using a bending tool. The retention of the band depends upon the resilience of the tube question, the ideal tube retains the degree of band which it is bent to I does not recover linearity over time.

A pipe 50, diameter 20 mm, of such construction as described in the previous examples, is secured in a pipe bending tool 100.

The pipe bending tool 100 is of a conventional type known in the industry and comprises two handles 108, 110 which are rotatable around a fulcrum 106. Fulcrum 106 acts as the axle for a wheel 102, which when seen side on has a groove to receive the pipe 50 (not shown on the diagram). The fulcrum also has a bracket 120 extending perpendicular to the first handle 108 and which has a clip to retain the pipe 50 in position against the wheel 102. Upon rotation of the second handle 110, which comprises a forming piece (rectangle shown halfway along the handle), the pipe 50 is retained by the clip of bracket 120 and thus conforms to the circumference (to the inside of the groove) of the wheel, which has a diameter of 12 cm. The handles 108 120 are rotated such as to become co-linear thus executing a 90° bend.

The pipe 50 is now bent pipe 52 and this is placed upon a measuring table having reference line 120 perpendicular to the stem of the pipe 52 such that when the pipe 52 relaxes and deviates from a perpendicular bend to provide pipe 54 the angle of deviation 122 is recorded. This angle of deviation is recorded over time. The experiments are carried out at ambient temperature, taken as 20°C. The rate of bending provides the bend in around 15 seconds. After bending the angle 122 is recorded: immediately after bending (i.e. the pipe is released from the tool and placed on a flat surface, taking approximately 10 seconds), after 30 minutes, after 24 hours and after 2 weeks. The tube is of length 50 cm, though this is not critical

Unless stated otherwise all pipe examples herein are 20mm diameter with 3mm thick walls. Any Binder layer may be 0.25mm thick tape. Any multiple Carrier polymer layers are of equal thickness. Any bonding layer can be taken as having a thickness of 0.25mm. unless otherwise stated any PE-RT used is Dowlex 2388.

Examples 2 to 5 and reference 1

Figure 1 shows a view of a multi-layered pipe (10) in cross-section according to a first embodiment of the invention. More specifically, Figure 1 shows a multi-layered pipe (10) having concentric layers of polymeric material being arranged sequentially on top of each other and consisting of a first Carrier polymer layer (12) forming a longitudinal axis of the pipe (10), a Binder layer (14) containing dispersed Binder polymer tapes/fibres disposed around the first Carrier polymer layer (12), and a second PE-RT layer (16) comprising a filler material disposed around the UHMWPE layer (14).

Example 1 is produced in 6 variants. With or without filler in each PE-RT layer and when filler is present it is present in either the first OR the second layer and at 11.25% or 22.5% inclusion.

The Talc filler in all examples unless otherwise stated is Granic 282 (TM) masterbatch from CRT Group which comprises 75% Talc (Dso 4pm) in PE and is included to provide, for example 22.5%, filler.

An alternative Talc filler is NS6130-02-289 having a particle size of (Dso) from Nanoshel which comprises Talc (Dso lOOnm (0.1pm). This may preferably be provided as a masterbatch in Carrier polymer for subsequent processing into the relevant polymer layer. The polymer of the masterbatch preferably been matched the polymer of the layer. Percentages of inorganic filler inclusion are by weight of the layer in which the filler is present, unless otherwise stated.

The multi-layered pipe (10) was produced by melt-extruding the first Carrier Polymer layer (12) forming a longitudinal axis of the pipe (10), melt-extruding the UHMWPE layer (14) around the first Carrier polymer layer (12) and applying the second (outer) Carrier polymer layer (16) containing the titanium dioxide around the UHMWPE layer (14).

Example 6

This is as Example 5 with the titanium dioxide material in the second Carrier Polymer layer (16) as a surface modified montmorillonite being a hydrated sodium calcium aluminium magnesium silicate hydroxide of the formula (N ,Ca)o.33(Al,Mg)2(Si40io)(OH)2-nH20) whose surface is modified with the quaternary ammonium salt Cloisite® 20A.

Example 8 and Reference 7

Figure 2 shows a view of a multi-layered pipe (20) in cross-section according to an alternative first embodiment of the invention. More specifically, Figure 2 shows reference 7 a multi-layered pipe (20) having concentric layers of polymeric material being arranged sequentially on top of each other and consisting of a first Carrier Polymer layer (22) forming a longitudinal axis of the pipe (20), a UHMWPE tape layer (24) disposed around the first Carrier polymer layer (22), and a second Carrier Polymer layer (26) disposed around the UHMWPE layer (24).

The multi-layered pipe (20) was produced by melt-extruding the first Carrier Polymer layer (22) forming a longitudinal axis of the pipe (20), melt-extruding the Binder layer (24) containing the titanium dioxide around the first Carrier Polymer layer (22) and applying the second (outer) Carrier Polymer layer (26) around the Binder layer (24).

Example 10 and Reference 9

Figure 3 shows a view of a multi-layered pipe (30) in cross-section according to an alternative first embodiment of the invention. More specifically, Figure 3 shows reference 9 a multi-layered pipe (30) having concentric layers of polymeric material being arranged sequentially on top of each other and consisting of a first Carrier Polymer layer (32) forming a longitudinal axis of the pipe (30), a first LDPE bonding layer (38a) comprising a titanium dioxide material disposed around the first Carrier Polymer layer (32), a Binder polymer tape layer (34) disposed around the first LDPE bonding layer (38a), a second LDPE bonding layer (38b) comprising a titanium dioxide material disposed around the Binder polymer tape layer (34) and a second Carrier Polymer layer (36) disposed around the second LDPE bonding layer (38b). The titanium dioxide material in each of the first (38a) and second (38b) LDPE bonding layers is a surface modified montmorillonite being a hydrated sodium calcium aluminium magnesium silicate hydroxide of the formula (Na,Ca)o33(Al,Mg)2(Si40io)(OH)2-nH20) whose surface is modified with the quaternary ammonium salt Cloisite® 20A.

In example 10, the pipe is as Reference 9 with, in the first Carrier Polymer layer (16) Granic 282 masterbatch which comprises 75% Talc in PE is included to provide 22.5% filler.

The multi-layered pipe (30) was produced by melt-extruding the first Carrier Polymer layer (32) forming a longitudinal axis of the pipe (30), applying the first LDPE bonding layer (38a) containing the titanium dioxide around the first Carrier Polymer layer (32), applying the Binder polymer tape layer (34) by winding layers of Binder polymer tape around the first LDPE bonding layer (38a), applying the second LDPE bonding layer (38b) containing the titanium dioxide around the Binder polymer tape layer (34) and applying the second (outer) Carrier Polymer layer (36) around the second LDPE bonding layer (38b).

Example 12 and Reference 11

Figure 4 shows a view of a multi-layered pipe (40) in cross-section according to an alternative first embodiment of the invention. More specifically, Figure 4 shows reference 11 a multi-layered pipe (40) having concentric layers of polymeric material being arranged sequentially on top of each other and consisting of a first Carrier Polymer layer (42) forming a longitudinal axis of the pipe (40), a first LDPE bonding layer (48a) disposed around the first Carrier Polymer layer (42), a Binder polymer tape layer (44) disposed around the first LDPE bonding layer (48a), a second LDPE bonding layer (48b) disposed around the Binder layer (44) and a second Carrier Polymer layer (46) comprising a titanium dioxide material disposed around the second LDPE bonding layer (48b). The titanium dioxide material is a surface modified montmorillonite being a hydrated sodium calcium aluminium magnesium silicate hydroxide of the formula (Na,Ca)o.33(Al,Mg)2(Si40io)(OH)2 //H2O) whose surface is modified with the quaternary ammonium salt Cloisite® 20A.

In example 12, the pipe is as Reference 11 with, in the first Carrier Polymer layer (16) Granic 282 masterbatch which comprises 75% Talc in PE is included to provide 22.5% filler.

The multi-layered pipe (40) was produced by melt-extruding the first Carrier Polymer layer (42) forming a longitudinal axis of the pipe (40), applying the first LDPE bonding layer (48a) around the first Carrier Polymer layer (42), applying the Binder layer (44) by winding layers of Binder polymer tape around the first LDPE bonding layer (48a), applying the second LDPE bonding layer (48b) around the Binder polymer tape layer (44) and applying the second (outer) Carrier Polymer layer (46) containing the titanium dioxide around the second LDPE bonding layer (48b).

Examples 14 to 20 and Reference 13

Reference 13 is a single layer Carrier polymer pipe. The pipe was produced by meltextruding the first Carrier Polymer layer forming a longitudinal axis of the pipe.

Examples 14 and 15 represent are with filler in the Carrier polymer 11.25% or 22.5% inclusion respectively.

The chalk filler is Mastercam 283 of Kilwaughter Lime introduced as masterbatch in PE. The Carrier polymer and Carrier polymer with fdler was also made into rectangular billets of 1cm by 15cn by 1mm test pieces and the following parameters measured using an Instron (TM) test machine such as a 6800 series machine.

Examples 21 and 22

Example; 21 as Example 13 with a layer of Binder polymer tape on the outer face of the tube.

Example; 22 as Example 16 with a layer of Binder polymer tape on the outer face of the tube.

Pipe bending, preliminary test results

An acceptable level of elastic, i.e. resilient recovery is taken as 5° or less, greater than this labelled as fail and further measurements are not provided. R designates reference samples, i.e. comprising no filler. Pass is 5° or less bending. Pass+ is no change within error, taken as 1° change in bend. *Loss of pipe strength on bending. Summary of results

The initial results show that Carrier polymer pipe is resilient and upon bending returns, at least to some extent, to its original shape. Similarly multilayered pipes comprising a significant Carrier Polymer layer component are similarly resilient. This is even more so when a Binder layer is included. The presence of nano clay is not an effective material to reduce this resilience. The provision of talc or chalk as fillers reduces resilience and when the pipe is bent the pipe is more likely to retain its curvature. As shown in the test results Talc is more effective than Chalk based upon its weight of inclusion however inclusion of 22.5% by weight of chalk significantly reduces resilient recovery of a bent pipe. Inclusion of 5.6 of talc is however ineffective with the inclusion of 11.25% or more of talc’s effective. However most effective range appears to be in the range 22.5% to 33.75% Talc in the Carrier Polymer layer of a pipe. Inclusion of high levels is also effective for pipe bending but appears to influence the resulting strength of the pipe.

In the present invention the term first layer should not be taken to be the innermost layer and the first layer of the present invention comprising the filler will normally be accompanied by an innermost layer of polymer not comprising any filler, most preferably an innermost layer of polymer consisting of said inorganic filler and Carrier polymer alone.

In the event of any perceived conflict in percentage incorporation in a polymer layer the defined polymer percentage predominates and the filler percentage is a percentage of the residual weight. Any residual percentage can be accommodated through functional materials as previously noted. All percentages are by weight in this document and less indicated otherwise.

In the present invention, including in the drawings and the disk detail description thereof detaining dioxide entertaining dockside layers are optional in the description can be read without requiring the inclusion of that material or of those layers.

The pipe of the present invention is preferably free from metal. The pipe of the present invention is preferably free from aluminium or copper . In this sense the metal is in the form of the metallic element not of the metal in ionic form . The absence of a metal improves the recyclability of the pipe, eliminates metallic corrosion and removes the problems of stress and oxidation hardening of metal which can greatly alter the bend ability of a pipe, such as its ability to be bent manually. The hydronic system of the present invention is preferably a heating hydronic system the heating hydronic system is preferably a central heating system utilising water filled radiators (in contrast to HVAC).

For any given pipe layer in the present invention which is described as comprising a given polymer that pipe layer may optionally consist of that polymer.

A plurality of layers of tape with one layer placed on top of the other may be described as being radially concentric. Relevant context is when Binder layer is formed from a Binder polymer tape and that layer optionally comprises a plurality of layers of tape with one layer placed on top of the other (i.e. they are radially concentric).

Claims

Claims,

1. A plastic pipe for conveying fluids the pipe comprising: a) a first, Carrier polymer layer comprising a carrier polymer being a polymer selected from one or more of : LDPE [low-density polyethylene]; HDPE: [high-density polyethylene]; LLDPE : [linear low-density polyethylene]; PEX : [polyethylene cross linked]; PP : [polypropylene]; PPR [PolyPropylene Random Copolymer]; PP-RCT [PolyPropylene Random Copolymer with modified Crystallinity and Temperature resistance] and RACO-PP : [random crystalline polypropylene] forming a longitudinal tubular axis of the pipe; the Carrier polymer layer comprising from 10% to 99% of a Carrier polymer and between 1% and 90% by weight of an inorganic filler having an average particle size of particle size (D50) of from 0.01pm to 40pm, preferably from 0.01pm to 4pm and b) an optional binder layer comprising a binder polymer.

2. The plastic pipe of claim 1 wherein the pipe is suitable for being bent manually through 90°.

3. The pipe of claim 1 or claim 2 wherein the inorganic filler is selected from one or more of Talc; Calcium Carbonate; Kaolinite; Wollastonite; Mica muscovite; Mica phlogopite; Glass beads or fibre; Calcium Silicate and Barium sulphate - BaSCE and mixtures thereof.

4. The pipe of claim 3 wherein the inorganic filler is Talc.

5. The pipe of any of claims 1 to 4 further comprising: b) a Binder layer disposed around the first Carrier polymer layer.

6. The pipe of any of claims 1 to 5 further comprising: c) a Binder layer disposed within the first Carrier polymer layer.

7. The pipe of claim 5 or claim 6 further comprising a c) second Carrier polymer or PE-RT layer and dl) disposed outside the previously claimed layer b) or d2) inside the previously claimed layer c).

8. The pipe of claim 7 further comprising an innermost PE-RT layer.

9. The pipe of claim 7 or 8 in which the Carrier polymer layer a) is surrounded by Binder layer b) which is in turn surrounded by a carrier polymer or PE-RT layer dl).

10. The pipe of any preceding claim in which at least one pipe layer does not comprise inorganic fdler and is an innermost layer of the pipe for contacting a fluid conducted through the pipe.

11. The pipe according to any preceding claim, wherein the thickness of the first Carrier polymer layer a) is in the range 0.5 to 8 mm.

12. The pipe according to any preceding claim, wherein the thickness of the second Carrier polymer or PE-RT layer b) is in the range 0.1 to 0.9 mm.

13. The pipe according to any of claims 5 to 12, wherein the thickness of the Binder layer is in the range 0.1 to 0.7 mm.

14. The pipe according to any of claims 5 to 13, wherein the Binder layer is formed from a Binder polymer tape and that layer optionally comprises a plurality of layers of tape with one layer placed on top of the other (i .e. radially concentric).

15. The pipe according to claim 17, wherein the two layers of tape have an angle of overlap between them of from 40° to 70° degrees.

16. The pipe according to any of claims 5 to 18, further comprising a bonding layer disposed between the first Carrier polymer layer and the Binder layer, and/or a bonding layer disposed between the second Carrier polymer or PE-RT layer and the Binder layer.

17. The pipe according to any preceding claim, having a density of less than 1.5 g/cm³.

18. The pipe according to any preceding claim, wherein the pipe consists of the stated layer (claim 1) or layers (claims 2 to 20), the layer or layers and comprises minor additives at less than 5% by weight of the composition of the pipe.

19. The pipe of any of claims 1 to 18 when the pipe is suitable for conveying hot water in a dwelling, for potable water supply or a hydronic system.

20. A method of manufacturing a polymer pipe according to any of claims 1 to 19, the method comprising the step of : a) melt-extruding Carrier Polymer with inorganic filler to provide a masterbatch; b) incorporating the masterbatch with further Carrier Polymer and melt extruding to form the pipe.

21. A method of manufacturing a multi-layered polymer pipe according to any of claims 5 to 20, the method comprising the steps of: b) melt-extruding the first Carrier polymer layer a) to form a longitudinal axis of the pipe; ci) melt-extruding a Binder layer b) over the first PE-RT layer; or cii) binding the first Carrier polymer layer with one or more layers of Binder polymer tape.