Improvements relating to extrusion of polymeric materials

Abstract

Improvements relating to extrusion of polymeric materials. An extruded product, such as a film, tube or cable / wire sheath, comprising a first layer and a second layer. The first layer comprises a polymeric material (A) having a repeating unit of the formula:-O-Ph-O-Ph-CO-Ph-I, and a repeating unit of the formula:-O-Ph-Ph-O-Ph-CO-Ph-II, where Ph represents an extensional phenyl moiety. The second layer may be a polyaryletherketone (PAEK), such as a polyetheretherketone (PEEK). The first layer is intended to reduce formation of deposits on a mold of an extrusion apparatus during extrusion of the product. A method of producing a product comprising a first layer and a second layer is also described, as well as the use of a polymeric material (A) for reducing the formation of deposits on a mold of an extrusion apparatus during extrusion of a second polymeric material.

Description

Technical Field

[0001] The present invention relates to an extruded product, a method of producing an extruded product, and uses of a polymeric material. In particular, the present invention relates to an extruded product that reduces the formation of deposits on the die of an extrusion apparatus during extrusion. Background Art

[0002] Elongated products having a specific, consistent cross-sectional profile (referred to herein as extruded products), such as films or tubes, can be formed using an extrusion process. A typical extrusion process involves forcing one or more flowable polymeric materials through an extrusion die. Such dies include an outlet for the polymeric material that is shaped to impart the desired cross-sectional profile to the product. Some polymeric materials have a tendency to adhere to the edges of the die outlet and gradually form a substantial deposit at the die outlet. Such deposits may be referred to as "die drool" (also known as "die build-up", "die drip", "die peel", "die bleed", or "plate out"), and can adversely affect product quality and the process, for example, by leaving marks on the surface of the extruded product, or by breaking and contaminating the product at random intervals.

[0003] During the process, it is often difficult or impossible to manually remove such die drool from the die without affecting the extruded product being formed. Thus, when such die drool forms and begins to adversely affect the quality of the product, it may be necessary to stop the process and clean the extrusion apparatus, particularly the die. This may involve disassembling the extrusion apparatus and thus cause significant downtime in the production process.

[0004] For these reasons, polymeric materials having a relatively high tendency to form die drool can only be used to produce extruded products in relatively short product production cycles, which is inefficient and thus more costly than processes using polymeric materials having a lower tendency to form die drool.

[0005] The problem may be exacerbated when the polymeric material includes a filler material, such as particulate fillers, such as talc. Such filler materials typically cause an increase in die drool formation. Such filler materials can provide benefits to the extruded product formed from the polymeric material, such as improved strength, rigidity, impact resistance, heat resistance, electrical insulation, and chemical stability. The benefits provided by such filler materials may outweigh the difficulties caused by the increased die drool. However, it would be desirable to reduce die drool during the process of producing an extruded product using such polymeric materials containing fillers, so that the efficiency of the process and the quality of the extruded product can be improved.

[0006] This problem may also be exacerbated when the extrusion equipment is operating at an increased line speed. When the line speed increases, the pressure in the die increases due to the increased extrusion screw speed, and this may cause more expansion of the melt as it exits the die, thereby increasing die fouling. It would be desirable to reduce die fouling in the production of extruded products so that higher line speeds can be used. SUMMARY OF THE INVENTION

[0007] Polyaryletherketones (PAEK), such as polyetheretherketone (PEEK) and polyetherketone (PEK), are well-known high-performance thermoplastic polymers that generally have excellent mechanical and chemical resistance properties. Filler materials, such as glass fibers, carbon fibers, and particulate materials such as talc, can further improve certain properties of these polymers. However, the inventors have found that the filler materials present in such polymers increase the tendency for die fouling to occur, and thus adversely affect the extruded products formed from such filled PAEK polymers and reduce the efficiency of their production processes.

[0008] An object of the present invention is to provide an extruded product, method, or use that addresses at least one disadvantage of the prior art (identified either herein or elsewhere), or to provide an alternative to existing extruded products, methods, and uses. For example, an object of the present invention may be to provide an extruded product that has a lower tendency to generate die fouling during extrusion than comparable extruded products.

[0009] According to aspects of the present invention, there are provided an extruded product, method, and use as set forth in the appended claims. Other features of the present invention will be apparent from the dependent claims and the following description.

[0010] According to a first aspect of the present invention, there is provided an extruded product comprising a first layer and a second layer; wherein the first layer comprises a polymer material (A) having:

[0011] a repeating unit of the formula:

[0012] -O-Ph-O-Ph-CO-Ph-I

[0013] and a repeating unit of the formula:

[0014] -O-Ph-Ph-O-Ph-CO-Ph-II

[0015] wherein Ph represents a phenylene moiety.

[0016] An extruded product means an elongated product whose cross-section has been formed by an extrusion process, suitably formed by extrusion through a die which imparts to the product a specific, preferably consistent, cross-sectional profile. The extruded product of this first aspect may alternatively be referred to as an elongated product which suitably has a consistent cross-section. Examples of such extruded products / elongated products include films, cable sheaths (including but not limited to wire and cable insulation), tubes and filaments.

[0017] The polymeric material (A) is a polyaryletherketone (PAEK) polymer. More specifically, the polymeric material (A) is a copolymer of poly(etheretherketone) (PEEK) and poly(etherdiphenyletherketone) (PEDEK), the repeating unit of formula I (which may be referred to as EEK) provides the PEEK polymer component, and the repeating unit of formula II (which may be referred to as EDEK) provides the PEDEK. Thus, the polymeric material of formula (A) may be referred to as a PEEK / PEDEK copolymer.

[0018] The inventors have found that the polymeric material (A) has a lower tendency to form die fouling when extruded through a die at elevated temperatures. Thus, an extruded product can be formed from the polymeric material (A) without, as discussed above, die fouling potentially adversely affecting product quality and process efficiency when extruding a similar polymer such as a PEEK homopolymer. In the extruded product of this first aspect, the polymeric material (A) provides a first layer which is an outer layer with a reduced tendency to form die fouling, which can effectively protect the second layer (which is the inner layer) from the die when leaving the extrusion equipment used to produce the extruded product, such that the second layer does not develop die fouling which would adversely affect product quality or process efficiency. This is particularly advantageous when the material of the second layer, suitably a second polymeric material, has a much higher tendency to form die fouling than the polymeric material (A). Thus, the extruded product of this first aspect suitably has fewer die fouling-induced defects than a comparable extruded product which does not include an outer layer of the polymeric material (A). In addition, the operating time of the extrusion process used to form the extruded product may be significantly longer before the process needs to be stopped to clean the extrusion equipment than a comparable process which does not include the use of an outer layer of the polymeric material (A). This suitably provides a more efficient overall process for producing such extruded products such as films, cable sheaths, filaments and tubes.

[0019] As described in more detail below, the present invention may also allow a higher content of fillers to be included in the polymeric material of the inner layer of the extruded product, compared to which would otherwise adversely affect the extrusion process in the absence of fillers. Such a higher content of fillers may be desirable for improving properties of the extruded product, such as corona discharge resistance.

[0020] In addition, the present invention also allows for the use of a higher line speed during the production of the extruded product. Increasing the line speed results in die fouling, which makes it impractical to increase the line speed beyond a certain limit. However, since the present invention reduces die fouling, it is possible to achieve a faster line speed, increasing manufacturing throughput and efficiency.

[0021] The polymeric material (A) can also provide other advantages in reducing other surface defects or strain-related phenomena (which can occur when extruding some polymeric materials, such as surface cracking of the extruded material) in the first layer that is the outer layer of the extruded product. The polymeric material (A) suitably has a much lower tendency to generate such defects.

[0022] The first layer is the outer layer of the extruded product. The term "outer layer" is used herein to denote one or more layers of the extruded product that contact the die used to form the product as it exits the die. In some embodiments, the extruded product is formed by a process in which only one surface of the product contacts the die as it exits. In such embodiments, the first layer is suitably the sole outer layer of the extruded product, typically the outermost layer or surface of the extruded product. The second layer is the inner layer of the extruded product. In some embodiments, the extruded product is formed by a process in which two surfaces of the product contact the die as it exits. In such embodiments, the extruded product includes a third layer and the second layer is disposed between the first layer and the third layer. In this embodiment, the extruded product suitably has only two outer layers, typically, the first layer is the first outer layer that is the outermost layer or surface of the extruded product, and the third layer is the second outer layer that is the innermost layer or surface of the extruded product.

[0023] The term "outer layer" or "first outer layer" can be used interchangeably with the term "first layer". The term "inner layer" can be used interchangeably with the term "second layer". The term "second outer layer" can be used interchangeably with the term "third layer".

[0024] Typically, the polymeric material (A) will have end units of the polymer, which can be the same as the repeating units, but with terminal OH or F groups. However, the method used to form the polymer can include an independent capping step at the end of polymerization, in which case a separate monomer or reagent can be added as a capping agent so that the end units can be different from the repeating units of the polymer. Such capping is well known in the field of nucleophilic polycondensation reactions.

[0025] The polymer preferably contains repeating units I and II in a molar ratio of I:II of 95:5 to 50:50 or 90:10 to 60:40.

[0026] The polymeric material (A) is suitably semi-crystalline and generally has a crystallization melting point lower than that of the homopolymer of repeating unit I or the homopolymer of repeating unit II. However, the glass transition temperature of the polymeric material (A) is generally the same as or slightly higher than the glass transition temperature of the homopolymer of repeating unit I. More specifically, the polymeric material (A) suitably has a glass transition temperature greater than 143 °C and at most 160 °C and a crystallization melting temperature of 300 °C and at most 330 °C. Specifically, a polymer containing repeating units I and II in a relative ratio of 80:20 has a glass transition temperature of about 149 °C and a crystallization melting temperature of about 309 °C.

[0027] The phenylene moiety (Ph) in each repeating unit may independently have a 1,4-para bond or a 1,3-meta bond bonded to the atom. When the phenylene moiety includes a 1,3-bond, this moiety will be in the amorphous phase of the polymer. The crystalline phase will include the phenylene moiety having a 1,4-bond. In many applications, the polymeric material is preferably highly crystalline, and thus, the polymeric material preferably includes a higher content of the phenylene moiety having a 1,4-bond.

[0028] Suitably, at least 95% or at least 99% of the number of phenylene moieties (Ph) in the repeating unit of formula I have a 1,4-bond bonded to the moiety. Particularly preferably, each phenylene moiety in the repeating unit of formula I has a 1,4-bond bonded to the moiety.

[0029] Suitably, at least 95% or at least 99% of the number of phenylene moieties (Ph) in the repeating unit of formula II have a 1,4-bond bonded to the moiety. Particularly preferably, each phenylene moiety in the repeating unit of formula II has a 1,4-bond bonded to the moiety.

[0030] Preferably, the phenylene moiety in the repeating unit of formula I is unsubstituted. Preferably, the phenylene moiety in the repeating unit of formula II is unsubstituted.

[0031] The repeating unit of formula I suitably has structure Ia:

[0032]

[0033] The repeating unit of formula II suitably has structure IIa:

[0034]

[0035] The polymeric material (A) may comprise at least 68 mol%, preferably at least 71 mol% of the repeating units of formula I. Particularly advantageous polymeric materials (A) may comprise at least 72 mol%, or in particular at least 74 mol% of the repeating units of formula I. The polymeric material (A) may comprise less than 90 mol%, suitably 82 mol% or less of the repeating units of formula I. The polymeric material (A) may comprise 68 to 82 mol%, preferably 70 to 80 mol%, more preferably 72 to 77 mol% of the units of formula I.

[0036] The polymeric material (A) may comprise at least 10 mol%, preferably at least 18 mol% of the repeating units of formula II. The polymeric material (A) may comprise less than 32 mol%, preferably less than 29 mol% of the repeating units of formula II. Particularly advantageous polymeric materials (A) may comprise 28 mol% or less; or 26 mol% or less of the repeating units of formula II. The polymeric material (A) may comprise 18 to 32 mol%, preferably 20 to 30 mol%, more preferably 23 to 28 mol% of the units of formula II.

[0037] The sum of the mol% of the units of formula I and II in the polymeric material (A) is suitably at least 95 mol%, preferably at least 98 mol%, more preferably at least 99 mol%, and in particular about 100 mol%.

[0038] The ratio defined as the mol% of the units of formula I divided by the mol% of the units of formula II may be in the range of 1 to 10, may be 1.8 to 5.6, suitably in the range of 2.3 to 4 and preferably in the range of 2.6 to 3.3.

[0039] Determined by differential scanning calorimetry (DSC), the polymeric material (A) suitably has a melting temperature (Tm) lower than that of the material of the inner layer. The melting temperature of the polymeric material (A) may be at least 10 °C, such as at least 20 °C, for example at least 30 °C lower than that of the material of the inner layer.

[0040] Other suitable polymeric materials of formula (A) (PEEK / PEDEK copolymers) are described in US 4717761, WO 2014 / 207458A1 and WO 2015 / 124903 A1, the contents of which are incorporated herein by reference.

[0041] WO 2014 / 207458 A1 discloses a PEEK / PEDEK copolymer having a molar ratio of repeating units of formula I and II of 55:45 to 95:5 and having a melt viscosity (MV) at 340 °C and 1000 s -1Measured at a shear rate of at least 0.25 and less than 1.2 kN s m -2 .

[0042] WO 2015 / 124903 A1 discloses a PEEK / PEDEK copolymer having repeating units of Formulas I and II in a molar ratio of 55:45 to 95:5, and a melt viscosity (MV) measured at a shear rate of 340 °C and 1000 s -1 of at least 0.25 and less than 1.2.

[0043] In some embodiments, the polymeric material (A) may be as described in WO 2022013520 A1, the content of which is incorporated herein by reference. In such embodiments, the polymeric material (A) may consist essentially of: repeating units of Formula I:

[0044] -O-Ph-O-Ph-CO-Ph-I;

[0045] repeating units of Formula IIa:

[0046]

[0047] and end units;

[0048] wherein the molar ratio of the repeating units of Formula I to the repeating units of Formula IIa is from 50:50 to 95:5; and

[0049] wherein the repeating units of Formula I consist essentially of:

[0050] 50 to 90 mol% of repeating units of Formula Ia:

[0051]

[0052] and 10 to 50 mol% of repeating units of Formula Ib, Formula Ic, or a mixture thereof;

[0053] wherein the repeating units of Formula Ib are:

[0054] and

[0055] the repeating units of Formula Ic are:

[0056]

[0057] Preferably, the molar ratio of the repeating units of Formula I to the repeating units of Formula II is from 50:50 to 95:5, preferably from 60:40 to 90:10, more preferably from 70:30 to 90:10.

[0058] The repeating units of formula I consist essentially of, or preferably consist of, 50 to 90 mol% of the repeating units of formula Ia and 10 to 50 mol% of the repeating units of formula Ib and / or formula Ic. Preferably, the repeating units of formula I consist essentially of, or preferably consist of, 65 to 90 mol% of the repeating units of formula Ia and 10 to 35 mol% of the repeating units of formula Ib, formula Ic or a mixture thereof. More preferably, the repeating units of formula I consist essentially of, or preferably consist of, 80 to 90 mol% of the repeating units of formula Ia and 10 to 20 mol% of the repeating units of formula Ib, formula Ic or a mixture thereof.

[0059] The repeating unit Ia is called R PEEK , the repeating unit Ib is called R mPEEK , and the repeating unit Ic is called R oPEEK .

[0060] Thus, in other words, the repeating units of formula I have (expressed as a molar ratio):

[0061] R PEEK :(R mPEEK +R oPEEK ), of 90:10 to 50:50, preferably 90:10 to 65:35, more preferably 90:10 to 70:30, even more preferably 90:10 to 80:20.

[0062] In a particularly preferred embodiment, the polymeric material (A) is a copolymer as described above, wherein the molar ratio of the repeating units of formula I to the repeating units of formula II is 90:10 to 70:30, and wherein the repeating units of formula I consist essentially of, or preferably consist of, 80 to 90 mol% of the repeating units of formula Ia and 10 to 20 mol% of the repeating units of formula IIb, formula Ic or a mixture thereof.

[0063] It should be understood that formula I: -O-Ph-O-Ph-CO-Ph- does not provide information on whether any of the bonds on the -O-Ph-O- moiety are arranged in a para, meta or ortho configuration, whereas formulae Ia, Ib and Ic do, and so do all other configurations within the repeating unit.

[0064] In one embodiment, the copolymer according to the first aspect of the present invention may be a copolymer that does not include the repeating units of formula Ib.

[0065] In another embodiment, the copolymer according to the first aspect of the present invention may be a copolymer that does not include the repeating units of formula Ic.

[0066] Suitably, the polymeric material (A) provides an outer layer of up to 100 wt%, suitably up to 95 wt% or up to 90 wt% of the outer layer. The polymeric material (A) can provide an outer layer of at least 70 wt%, at least 80 wt% or at least 85 wt%. Suitably, the polymeric material (A) provides an outer layer of 70 to 100 wt%, 80 to 95 wt% or 85 to 95 wt%.

[0067] Suitably, the first layer consists essentially of or consists of the polymeric material (A) as defined above.

[0068] The first and second layers of the extruded product can have a combined thickness of at most 5 mm, suitably at most 3 mm or at most 2 mm. Suitably, the first and second layers of the extruded product can have a combined thickness of at least 10 μm, suitably at least 50 μm or at least 100 μm.

[0069] The thickness of the first layer is suitably lower than the thickness of the second layer. The second layer can provide 50% to 95% of the combined thickness of the first and second layers. The first layer suitably provides 5% to 50% of the combined thickness of the first and second layers.

[0070] Suitably, the extruded product of this first aspect comprises a third layer. The third layer is a second outer layer. In such embodiments, the first layer mentioned above can be regarded as the first outer layer. Suitably, the second layer is disposed between the first layer and the third layer. Thus, the extruded product suitably has an A-B-A sandwich structure, where the A layers are the first outer layer and the second outer layer, and the B layer is the inner layer.

[0071] Suitably, the third layer comprises the polymeric material (A) as described above, that is, the polymeric material (A) having:

[0072] Repeat units of the formula:

[0073] -O-Ph-O-Ph-CO-Ph-I

[0074] And repeat units of the formula:

[0075] -O-Ph-Ph-O-Ph-CO-Ph-II

[0076] Wherein Ph represents a phenylene moiety.

[0077] Suitably, the third layer consists essentially of or consists of the polymeric material (A) as defined above. Suitably, the third layer is the same as the first layer.

[0078] The first layer and / or the third layer may comprise a release agent. Suitably, the first layer comprises a release agent. Suitable release agents are known in the art and may be selected from metal stearates, erucamide, oleamide or fluoropolymers.

[0079] The second layer of the extruded product of this first aspect may comprise a polymeric material, which may be referred to as the second polymeric material. Suitably, the second layer comprises a polyaryletherketone (PAEK). Suitably, the second layer comprises a PEEK polymer, i.e., a polymeric material (B) having repeating units of the following formula:

[0080] -O-Ph-O-Ph-CO-Ph-I

[0081] where Ph represents a phenylene moiety.

[0082] Suitably, at least 95% or at least 99% of the number of phenylene moieties (Ph) in the polymeric material (B) have 1,4-bonds bonded to the moiety. Particularly preferably, each phenylene moiety in the polymeric material (B) has a 1,4-bond bonded to the moiety.

[0083] Suitably, the phenylene moiety in the repeating unit of formula I is unsubstituted.

[0084] The polymeric material (B) may comprise at least 68 mol%, preferably at least 71 mol% of repeating units of formula Ia:

[0085]

[0086] Suitably, the polymeric material (B) comprises at least 80 mol%, preferably at least 90 mol%, more preferably at least 95 mol%, especially at least 99 mol% of repeating units of formula I, especially repeating units of formula Ia. Thus, the polymeric material (B) is preferably a homopolymer, which is preferably polyetheretherketone (PEEK).

[0087] Suitable PEEK polymeric materials are available from Victrex Manufacturing Limited, such as VICTREX PEEK 150G, 151G, 381G, 450G, 650G (all are examples of PEEK polymeric materials). VICTREX AE TM 250 is an example of a PEEK-PEDEK polymeric material.

[0088] PAEK, especially including PEEK, can be manufactured by the nucleophilic polycondensation of bisphenols with organic dihalide compounds in a suitable solvent in the presence of alkali metal carbonate and / or bicarbonate or alkaline earth metal carbonate and / or bicarbonate. Such processes are described, for example, in EP0001879A, EP0182648A, EP0244167A, and EP3049457A. PAEK can be manufactured according to WO2018055384 which is incorporated herein by reference.

[0089] Such polyaryletherketones can have a relatively high melting temperature and can be prone to oxidation and other degradation processes during the extrusion process, which can produce die build-up as discussed above.

[0090] Suitably, the second layer of the extruded product in this regard contains a filler material. The filler material can account for at least 5 wt%, suitably at least 10 wt% or at least 15 wt% of the second layer material. The filler material can provide up to 50 wt%, up to 40 wt% or up to 30 wt% of the second layer. Suitably, the filler material provides 5 to 50 wt% of the second layer, 10 to 40 wt% of the second layer or 15 to 35 wt% of the second layer. Compared to the case where there is no filler originally which would adversely affect the extrusion process, the present invention allows a higher content, for example greater than 20 wt%, preferably 25 wt% or 30 wt% or 40 wt% of the filler to be included in the polymer material of the inner layer of the extruded product. Such a higher content of the filler can be desirable for improving the properties of the extruded product, such as corona discharge resistance.

[0091] In such embodiments, the second polymer material, such as polymer material (B), suitably provides up to 95 wt% of the second layer material, suitably provides up to 90 wt% or up to 85 wt% of the second layer. The second polymer material can provide at least 50 wt%, at least 60 wt% or at least 70 wt% of the second layer. Suitably, the second polymer material provides 50 to 95 wt% of the second layer, 60 to 90 wt% of the second layer or 65 to 85 wt% of the second layer.

[0092] The filler material can be a fibrous filler material or a particulate filler material.

[0093] The fibrous filler material suitably has a longest dimension of 300 μm or less. Suitable fibrous filler materials can be selected from inorganic fibrous materials, organic fibrous materials (such as polyaramid fibers and carbon fibers). Preferably, the melting temperature of the fibrous filler should be at least 450 °C. Suitable fibrous filler materials can be selected from glass fibers, carbon fibers, asbestos fibers, silica fibers, alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, fluorocarbon resin fibers, and potassium titanate fibers or mixtures thereof. Preferred fibrous fillers are glass fibers and carbon fibers.

[0094] In some embodiments, the filler material is a particulate filler material. Suitable particulate (or non-fibrous) filler materials may be selected from mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, boron nitride powder, magnesium carbonate, fluorocarbon resin, graphite, graphene, graphene oxide, carbon powder, ceramic powder, metal powder, flame retardant powder, nanotubes, and barium sulfate, or mixtures thereof. The particulate filler material may be introduced in the form of a powder or flake particles. The particulate filler material is suitably talc.

[0095] The particle size of the filler material is suitably in the range of 1 to 10 μm, suitably in the range of 2 to 5 μm. In some embodiments, the filler material is in the form of flakes.

[0096] Preferably, the D50 of the filler material is between 0.001 and 50 μm, more preferably between 0.005 and 15 μm. It is preferred that the filler material has a D50 of less than 10 μm. Preferably, the D50 of the filler material is between 1 and 5 μm, for example between 3 and 5 μm. The D50 is measured by laser diffraction using a laser Mastersizer and Mie theory (according to ISO 13320-1).

[0097] Suitably, the filler material provides improved properties, such as improved strength, ductility, heat resistance, chemical resistance, or electrical resistance, to a second layer material, such as the polymer material (B) as defined above. For example, the filler material may provide improved dielectric properties and / or electrical breakdown performance. In embodiments where the filler material is talc and the extruded product is a coating or sheath for an electrical wire, the talc filler suitably improves the electrical breakdown properties of the wire coating at relatively high voltages, such as 800 V. In particular, such electrical wires may be suitable for electric motors, where high voltage may be advantageous in reducing power losses.

[0098] As discussed above, including such filler materials can lead to an increase in die fouling and thus impair the quality of the extruded product and the efficiency of the production process. Therefore, when a second layer, such as the polymer material (B) as defined above, contains such filler materials, the extruded product of this first aspect can be particularly advantageous. In such embodiments, the extruded product suitably provides the following beneficial properties: having the filler material in the body of the product (in the inner layer), while avoiding the associated tendency to form die fouling during extrusion due to the outer layer of polymer material (A) covering the second layer.

[0099] The second layer material containing the filler material can be prepared by any suitable method known in the art. Appropriately, the second layer material containing the filler material is prepared by single-screw or twin-screw extrusion compounding, preferably by twin-screw extrusion compounding.

[0100] Appropriately, the second layer of the extruded product of this first aspect consists of or consists essentially of the second polymer material as defined above and any filler material present.

[0101] The first layer and / or the second layer and / or the third layer may contain one or more pigments to change the color of the material. This is useful for identifying the material during the manufacturing process. Optionally, the pigment may be TiO 2 or carbon black.

[0102] In some embodiments of the extruded product of this first aspect, the extruded product is in the form of a film. Appropriately, the film comprises a first outer layer of polymer material (A) as the first layer; an inner layer of polymer material (B) as the second layer; and a second outer layer of polymer material (A) as the third layer, wherein the second layer is disposed between the first layer and the third layer (in an A-B-A arrangement). Appropriately, the second layer contains the polymer material (B) and the filler material as defined above. Appropriately, the first layer of polymer material (A), the third layer of polymer material (A), and the second layer of polymer material (B) are coaxially arranged to form a film.

[0103] The film may have a total thickness of 3 to 1,000 mm. The second layer appropriately provides 40% to 90% of the total thickness of the film. The first and / or third layer appropriately provides 5% to 30% of the total thickness of the film.

[0104] For applications where the film is used as a coating, for example, coated on a wire for the final application of insulating a conductor, the typical range will be in the sub-micron range. For this purpose, the total thickness of the film can be 3 to 1,000 μm. The second layer appropriately provides 40% to 90% of the total thickness of the film. The first and / or third layer appropriately provides 5% to 30% of the total thickness of the film.

[0105] In some embodiments of the extruded product of the first aspect, the extruded product is in the form of a tube. Appropriately, the tube comprises a first outer layer of polymer material (A) as the first layer, an inner layer of polymer material (B) as the second layer, and a second outer layer of polymer material (A) as the third layer, wherein the second layer is disposed between the first layer and the third layer (in an A-B-A arrangement). Appropriately, the second layer contains the polymer material (B) and the filler material as defined above.

[0106] In such embodiments, the tube may have a wall thickness of 0.5 to 10 mm. The second layer appropriately provides 40% to 90% of the wall thickness of the tube. The first and / or third layer appropriately provides 5% to 30% of the wall thickness of the tube.

[0107] In such embodiments, the inclusion of the polymeric material (A) can advantageously improve the physical properties of the tube by reducing the adverse effects of die fouling, especially in the case of tubes that include fillers such as talc in the second (inner) layer, which tubes that include fillers may otherwise have an increased tendency to form die fouling. This can allow for the production of tubes that are longer in length than would otherwise be possible to a greater extent in the presence of die fouling. By reducing die fouling, longer and faster run times may also be possible, thus providing increased manufacturing efficiency.

[0108] The tube can have a length of at least 5 m, at least 10 m, at least 50 m or at least 100 m, suitably having a substantially constant cross-section along its entire length, and suitably formed in a single continuous extrusion. In some embodiments, the tube can have a length of at least 500 m, at least 1 km or at least 2.5 km.

[0109] The tube can have an outer diameter of at least 0.5 cm, at least 2.5 cm, at least 10 cm or at least 15 cm. The tube can have an outer diameter of less than 50 cm, less than 40 cm or less than 30 cm. In some embodiments, the tube has an outer diameter in the range of 0.5 cm to 50 cm. In some embodiments, the tube has an outer diameter in the range of 2.5 cm to 30 cm.

[0110] The outer diameter of the tube can be defined as "d" cm, and the thickness of the tube wall can be defined as "t" cm. Thus, the diameter-to-thickness ratio (d / t) of the tube can be defined. In some embodiments, the diameter-to-thickness ratio of the tube is at least 6. The diameter-to-thickness ratio of the tube can be in the range of 6 to 40 or 15 to 40.

[0111] In some embodiments of the extruded product of this first aspect, the extruded product is in the form of an electrical wire or cable sheath. Suitably, the electrical wire or cable sheath comprises an outer layer of polymer material (A) as the first layer and an inner layer of polymer material (B) as the second layer. Suitably, the first layer of polymer material (A) and the second layer of polymer material (B) are coaxially arranged to form the electrical wire or cable sheath. The electrical wire or cable sheath can be directly extruded onto the electrical wire or cable to surround the cable or wire. Thus, the extruded product can be regarded as an electrical cable or wire assembly comprising an inner cable or wire and a sheath, where the sheath surrounds the wire or cable and the sheath comprises the first layer of polymer material (A) and the second layer of polymer material (B) as described above. In such embodiments, the second layer suitably comprises a filler material, suitably a particulate filler material, which provides increased electrical insulation to the second layer and thus to the entire sheath. In such embodiments, the A-B arrangement of the layers can be particularly suitable for the production of an electrical wire or cable where the electrical wire or cable sheath exits the extruder in contact with the wire or cable being coated. The first layer of polymer material (A) suitably reduces or prevents the formation of die build-up on the upper surface of the second layer of polymer material (B), which would otherwise form on the die when the polymer material (B) exits the die of the extruder. Die build-up formed on the lower surface of the second layer of polymer material (B) is suitably avoided by the second layer coming into direct contact with the electrical wire or cable as it exits the extruder.

[0112] In some embodiments of a wire or cable sheath, the wire or cable sheath may comprise a first outer layer of a polymer material (A) as a first layer, an inner layer of a polymer material (B) as a second layer, and a second outer layer of the polymer material (A) as a third layer, wherein the second layer is disposed between the first layer and the third layer (in an A-B-A arrangement). Suitably, the first layer of the polymer material (A), the third layer of the polymer material (A), and the second layer of the polymer material (B) are coaxially arranged to form the wire or cable sheath. The wire or cable sheath can be directly extruded onto the wire or cable. Thus, the extruded product can be regarded as a cable or wire assembly comprising an inner cable or wire and the sheath, the sheath comprising the first layer of the polymer material (A), the third layer of the polymer material (A), and the second layer of the polymer material (B), as described above. In such embodiments, the second layer suitably comprises a filler material, suitably a particulate filler material, which provides increased electrical insulation to the second layer and thus to the entire sheath. In such embodiments, the A-B-A arrangement of the layers may be particularly suitable for manufacturing a wire or cable, where the wire or cable sheath exits the extruder without contacting the wire or cable and then contacts the wire or cable. The two outer layers of the polymer material (A) suitably reduce or prevent the formation of die build-up on the upper and lower surfaces of the second (inner) layer of the polymer material (B), which would otherwise form when the polymer material (B) exits the extruder.

[0113] Suitably, the second layer comprises talc, and suitably, the flakes of talc have a particle size in the range of 1 to 10 μm or 2 to 5 μm.

[0114] As discussed above, such filler materials can provide improved dielectric properties and / or electrical breakdown performance, especially improved electrical breakdown performance of the wire sheath at relatively high voltages such as 800 V. Additionally, such filler materials can provide improved resistance to corona discharge in an electric machine. Such wires may be particularly suitable for electric motors, where a high voltage can be advantageous in reducing power losses.

[0115] In such embodiments, the first and second layers of the wire or cable sheath may have a combined thickness in the range of 50 to 300 μm, suitably in the range of 100 to 200 μm. The first, second, and third layers may have the same combined thickness.

[0116] The wire or cable within the wire or cable sheath may have a circular cross-section. In some embodiments, the wire or cable may have a rectangular, square, hexagonal, or stranded cross-section. The cross-section of the wire or cable may have an area of 1 mm 2 to 100 mm 2 , suitably 2 mm 2 to 80 mm 2or 2 mm 2 to 10 mm 2 。

[0117] The thickness of the first layer and / or the third layer is suitably less than the thickness of the second layer of the wire or cable sheath. The second layer may provide from 50% to 95% of the combined thickness of the first layer and the second layer or the first, second and third layers. The first layer and / or the third layer suitably provide from 5% to 50% of the combined thickness of the first layer and the second layer or the first, second and third layers.

[0118] The wire or cable assembly may include a fourth layer disposed between the cable or wire and the second layer. The fourth layer may be an adhesive layer which suitably improves the adhesion of the sheath to the cable or wire.

[0119] In some embodiments of the extruded product of this first aspect, the extruded product is in the form of a filament. Such filaments can be used as input materials for additive manufacturing. Suitably, the filament comprises a first layer of polymer material (A) and a second layer of polymer material (B), wherein the second layer forms the core of the filament and the first layer surrounds the core. Suitably, the first layer of polymer material (A) and the second layer of polymer material (B) are coaxially arranged to form the filament.

[0120] In such embodiments, the thickness of the filament may be from 0.2 to 5 mm, suitably from 1.0 mm to 3.0 mm or from 1.5 mm to 2.0 mm. The second layer suitably provides from 50% to 95% of the filament thickness. The first layer suitably provides from 5% to 50% of the filament thickness.

[0121] Such filaments may advantageously include in the core (i.e., the second layer) a filler as defined above, such as a conductive filler, which would otherwise cause die fouling during extrusion in the absence of the outer (first) layer of polymer material (A), and this outer layer prevents the core from contacting the surface of the die exit during extrusion from the die.

[0122] According to a second aspect of the present invention, there is provided a method of producing a product comprising a first layer and a second layer, the method comprising the steps of:

[0123] a) providing a source of polymer material (A) which has:

[0124] repeating units of the formula:

[0125] -O-Ph-O-Ph-CO-Ph-I

[0126] and repeating units of the formula:

[0127] -O-Ph-Ph-O-Ph-CO-Ph-II

[0128] wherein Ph represents a phenylene moiety;

[0129] b) Provide a source of the second polymeric material;

[0130] c) Deliver the polymeric material (A) and the second polymeric material to an extrusion head comprising a die;

[0131] d) Extrude the polymeric material (A) and the second polymeric material through the die such that the polymeric material (A) contacts the outlet of the die during extrusion and the second polymeric material does not contact the die during extrusion to form the extruded product.

[0132] The steps of the method are suitably carried out in the order of steps a) and b) (suitably, simultaneously), then step c), then step d).

[0133] Suitably, the input and extrusion of the polymeric material (A) and the second polymeric material are arranged such that at the outlet of the die the second polymeric material is covered by the polymeric material (A) such that the second polymeric material does not contact the outlet of the die. Suitably, the polymeric material (A) forms an outer layer surrounding the second polymeric material, and the second polymeric material forms an inner layer of the extruded product at or just before leaving the die. Accordingly, the polymeric material (A) prevents the second polymeric material from contacting the surface of the die at or near the outlet of the die so as to provide a reduction in die fouling as described herein.

[0134] The polymeric material (A) may have any suitable features and advantages as described above with respect to the first aspect.

[0135] The product produced by the method of this second aspect may have any suitable features or advantages of the extruded product as described above with respect to the first aspect. The polymeric material (A) provided in step a) suitably provides the first layer of the extruded product as described with respect to the first aspect. The second polymeric material provided in step b) suitably provides the second layer of the extruded product as described with respect to the first aspect.

[0136] The second polymeric material provided in step b) may have any suitable features and advantages of a second layer material, i.e., the second polymeric material is suitably the polymeric material (B) as described with respect to the first aspect.

[0137] The method of this second aspect suitably causes a reduction in die fouling compared to comparable processes in which the second polymer material is extruded through the die without the polymer material (A), and thus in which the second polymer material contacts the die, especially the die exit, during extrusion. Thus, when an extruded product is to be produced from the second polymer material, such as the polymer material (B) described above which may contain a filler material, this method is particularly advantageous, although it has advantageous properties, it causes die fouling, which adversely affects the quality of the product and reduces the efficiency of the production process due to the need to periodically stop the process and remove die fouling deposits.

[0138] In addition, the method of the present invention provides a higher line speed for producing the extruded product. Increasing the line speed causes die fouling, which makes it impractical to increase the line speed above a certain limit. However, since the present invention reduces die fouling, it is possible to achieve a faster line speed, increasing the manufacturing throughput and efficiency. Typically, the extrusion assembly can operate at approximately 10 meters per minute. Advantageously, the present invention provides a line speed of approximately 50 meters per minute or higher. Preferably, the line speed can be less than 100 meters per minute, preferably between 30 meters per minute and 80 meters per minute, preferably between 40 meters per minute and 60 meters per minute.

[0139] Suitably, the second polymer material contains a filler as described with respect to the first aspect. As discussed above, the presence of the filler material in the polymer material can lead to an increase in the formation of die fouling.

[0140] The method of this second aspect can be carried out on a suitable extrusion apparatus comprising a first supply means for feeding the polymer material (A) in molten form to the extrusion die and a second supply means for feeding the second polymer material in molten form to the extrusion die, the supply means being such that the second polymer material is extruded as an inner layer and the polymer material (A) is extruded as an outer layer in the product (i.e., the first and second layers described herein).

[0141] Step c) of the method suitably involves delivering the polymer material (A) to an extrusion table comprising a die to provide a first outer layer of the product and a second outer layer of the product, the second polymer material forming an inner layer disposed between the first outer layer and the second outer layer (i.e., the first, second and third layers as described herein). This suitably involves an extrusion apparatus comprising a third supply means for feeding a second stream of the polymer material (A) in molten form to the extrusion die to provide the second outer layer of the product.

[0142] Suitably, step d) is carried out at a temperature of at least 300 °C, at least 320 °C or at least 350 °C. Suitably, step d) is carried out at a temperature of at most 430 °C, at most 400 °C or at most 380 °C.

[0143] Preferably, when the polymeric material (B) is PEEK or PEEK and filler (e.g., PEEK filled with 30% talc), then suitably step (d) is carried out at a temperature greater than the melting temperature of the polymeric material (B) and preferably at at least 350 °C.

[0144] Preferably, step (d) is carried out at a temperature greater than the melting temperature of the polymeric material (A) and preferably at at least 325 °C.

[0145] Suitably, the temperature is the temperature of the die during the process, suitably, the temperature at the die outlet during the process.

[0146] Suitably, the process is carried out continuously for at least 1 hour, at least 5 hours, at least 10 hours, at least 15 hours or at least 24 hours. Compared to a similar process in which the polymeric material (A) is not used as the layer in contact with the die outlet, the reduction of die fouling provided by using the polymeric material (A) suitably allows an increase in the running time of the process for producing the product by extrusion.

[0147] According to a third aspect of the present invention, there is provided a use of a polymeric material (A) for reducing the formation of deposits on the die of an extrusion apparatus during the extrusion of a second polymeric material; wherein the polymeric material (A) has:

[0148] Repeating units of the formula:

[0149] -O-Ph-O-Ph-CO-Ph-I

[0150] And repeating units of the formula:

[0151] -O-Ph-Ph-O-Ph-CO-Ph-II

[0152] Wherein Ph represents a phenylene moiety.

[0153] The polymeric material (A) and the second polymeric material may have any suitable features and advantages as described above with respect to the first and second aspects.

[0154] Suitably, the reduction in the formation of deposits (die fouling) on the die of the extrusion apparatus during extrusion provided by this third aspect is compared to a similar process of extruding the same second polymeric material in the absence of the polymeric material (A). Suitably, using this third aspect reduces defects in the extruded product caused by die fouling and / or extends the running time of the extrusion process before the process needs to be stopped and the deposits on the die removed.

[0155] Typically, die fouling deposits are carbonaceous and thus conductive, which is a major drawback in the field of electrical insulation.

[0156] Advantageously, in use of this third aspect, the polymeric material (A) is arranged as an outer layer on the second polymeric material. BRIEF DESCRIPTION OF THE DRAWINGS

[0157] For a better understanding of the present invention, and in order to show how the exemplary embodiments may be carried out, reference will now be made to the accompanying drawings, in which:

[0158] Figure 1a is a schematic view of an extrusion die for producing an extruded product of the first aspect of the present invention in the form of a cable or wire assembly using the method of the second aspect of the present invention.

[0159] Figure 1b is a cross-section of an extruded product produced by an extrusion process through Figure 1a .

[0160] Figure 2a is a schematic view of an alternative extrusion die for producing an extruded product of the first aspect of the present invention in the form of a cable or wire assembly using the method of the second aspect of the present invention.

[0161] Figure 2b is a cross-section of an extruded wire or cable sheath produced by an extrusion process through Figure 2a .

[0162] Figure 3a is a schematic view of an alternative extrusion die for producing an extruded product of the first aspect of the present invention in the form of a cable or wire assembly using the method of the second aspect of the present invention.

[0163] Figure 3b is a cross-section of an extruded wire or cable sheath produced by an extrusion process through Figure 3a .

[0164] Figure 4a is a schematic view of an extrusion die for producing an extruded product of the first aspect of the present invention in the form of a tube using the method of the second aspect of the present invention.

[0165] Figure 4b is a cross-section of an extruded tube produced by an extrusion process through Figure 4a .

[0166] Figure 5a is a schematic view of an extrusion die for producing an extruded product of the first aspect of the present invention in the form of a film using the method of the second aspect of the present invention.

[0167] Figure 5b is a cross-section of an extruded film produced by an extrusion process through Figure 5a .

[0168] Figure 6a Schematic diagram of an extrusion die for producing an extruded product of the first aspect of the present invention in the form of filaments using the method of the second aspect of the present invention.

[0169] Figure 6b Is through Figure 6a Cross-section of the extruded filament produced by the extrusion process. Detailed Description

[0170] Figure 1a Shows a pressure extrusion die 100 for producing an extruded wire or cable assembly in a "pressure on" extrusion process, where the sheath contacts the wire or cable within the die. The extrusion die includes a die body 1 and a die mandrel 2. The die 100 includes a first channel 101, a second channel 102, a third channel 103, and a die outlet 110. The first and second channels are for supplying molten polymer materials A and B under pressure. The molten polymer material A forms the first (outer) layer of the extruded product having the composition described above for the polymer material (A). The molten polymer material B forms the second (inner) layer of the extruded product and is suitably the polymer material (B) as described above.

[0171] The wire or cable 3 is passed through the third channel for coating the sheath with polymers A and B. A, B, and 3 are fed through the die 100 to the die outlet 110, where the polymer material B contacts and coats the wire or cable 3 within the die, and then also within the die body, the polymer material A contacts and coats the polymer material B to continuously produce an extruded product comprising a wire or cable 3 surrounded by a sheath having a first (outer) layer 111 of A and a second (inner) layer 112 of B. This structure is shown in Figure 1b Cross-section. The formation of this extruded wire or cable assembly is carried out with a reduced amount of die deposits (die fouling) formed at the die outlet 110, since the polymer material A has a lower tendency to form such deposits compared to the second polymer material B, which may advantageously contain a filler material. Such filler materials suitably improve the electrical breakdown resistance of the polymer material B and thus the electrical breakdown resistance of the wire or cable sheath. The outer layer of A effectively insulates the polymer material B from the thermally exposed surfaces of the die 100, especially at the die outlet 110, which would otherwise cause die fouling of the polymer material B. Thus, compared to similar processes and products, in this arrangement, the extrusion method and extruded product suitably provide a beneficial reduction in die fouling.

[0172] Figure 2aAn extrusion die 200 formed by a die body 1 and a die mandrel 2 is shown. The die 200 includes a first channel 201, a second channel 202, a third channel 203, a fourth channel 204, and a die outlet 210 for producing an extruded wire or cable assembly in a "pressure" extrusion process, where the sheath contacts the wire or cable within the die. The first, second, and third channels are for supplying molten polymer materials A, B, and C, respectively. These polymer materials are fed under pressure through the die 200 to the die outlet 210 to continuously produce an extruded product, such as Figure 2b as shown, the extruded product includes three layers 211, 212, and 213 arranged coaxially around the wire 3, and the layers correspond to the polymer materials respectively supplied to the channels 201, 202, and 203.

[0173] As described above Figure 1a in the embodiment of, the wire or cable 3 is passed through the third channel for use in coating the sheath with polymers A, B, and C. A, B, C, and 3 are fed through the die 200 to the die outlet 210, where the polymer material B contacts and coats the wire or cable 3 within the die, also within the die body, the polymer material C contacts and coats the polymer material B, and then the polymer material A contacts and coats the polymer material C to continuously produce an extruded product including a wire or cable 3 surrounded by a sheath having an outer layer of A and inner layers of B and C.

[0174] The molten polymer material A forms the outer layer of the extruded product and has the composition described above for the polymer material (A), i.e., the first layer as described herein. The molten polymer material B forms the inner layer of the extruded product and is suitably the polymer material (B) as described above for the second layer. The molten polymer material C forms the second inner layer of the extruded product and may be the polymer material (B) as described above. The polymer material C suitably contains a filler that improves the electrical breakdown resistance of the polymer material C and thus improves the electrical breakdown resistance of the wire or cable sheath. Suitably, the polymer material B provides improved adhesion between the polymer material C and the wire 3 compared to the adhesion that would be obtained if the polymer material C directly contacted the wire 3.

[0175] As described above regarding Figure 1a the outer layer of A effectively insulates the polymer materials B and C from the thermally exposed surfaces of the die 200, especially at the die outlet 210, otherwise the thermally exposed surfaces would cause die fouling of the polymer material B or C. Thus, compared to similar processes and products, in this arrangement, the extrusion method and the extruded product suitably provide a beneficial reduction in die fouling.

[0176] Figure 3aShow a mold 300 formed by a mold body 1 and a mold mandrel 2. The mold 300 has an input arrangement similar to that of the mold 200, but is configured as a "tube-on" mold to coat an electrical wire or cable 3 with a sheath having a first outer layer 311 (i.e., the first layer) of A, an inner layer 312 (i.e., the second layer) of B, and a second outer layer 313 (i.e., the third layer) of A. Coating the electrical wire or cable 3 with the sheath occurs outside the mold body 300 after the sheath has exited the mold through the mold outlet 310. Thus, in such tube-on processes, the outermost and innermost surfaces of the sheath contact the heat-exposed surfaces of the mold 300 at the mold outlet 310 and may therefore be at risk of generating mold fouling. The electrical wire or cable produced in this way comprises three layers 311, 312, and 313 coaxially arranged around the wire 3 as shown in Figure 3b in which the layers correspond to polymeric materials respectively supplied to channels 301, 302, and 303. As shown, formation of the sheath from the polymeric materials A and B occurs within the mold body such that the first and second outer layers of A effectively insulate the polymeric material B from the heat-exposed surfaces of the mold 300, as discussed above, to reduce or eliminate mold fouling when the sheath exits the mold. As in the embodiments described with respect to FIGS. 1 and 2, the molten polymeric material A has the composition described above for polymeric material (A). The molten polymeric material B forms the inner layer of the extruded product and is suitably the polymeric material (B) as described above. The polymeric material B suitably contains a filler that imparts electrical breakdown resistance to the polymeric material (B).

[0177] Figure 4a Show an extrusion die 400 for forming a tube, the die being formed by a mold body 1 and a mold mandrel 2. The die 400 comprises a first channel 401, a second channel 402, a third channel 403, a fourth channel 404, and a mold outlet 410. The first, second, and third channels are for supplying molten polymeric materials under pressure, the molten polymeric materials being fed through the die 400 to the mold outlet 410 to continuously produce an extruded tube product that comprises as shown in Figure 4bThe three layers 411, 412, and 413 shown in [Figure 0] correspond to polymer materials supplied to channels 401, 402, and 403, respectively. The fourth channel 404 contains pins 3 to create the hollow center 414 of the tube. The molten polymer material supplied to the first channel 401 is the polymer material (A) as described above. The molten polymer material supplied to the second channel 402 is the second polymer material as described above, e.g., the polymer material (B) as described above. The molten polymer material supplied to the third channel 403 is the polymer material (A) as described above. Thus, the die 400 is used to produce an extruded product that includes an inner layer (i.e., the second layer) of the second polymer material disposed between two outer layers (i.e., the first and third layers) of the polymer material (A). The formation of this extruded product is carried out with a reduced amount of die deposits (die fouling) formed at the die outlet 410 because the polymer material (A) has a lower tendency to form such deposits compared to the second polymer material, which may contain filler material. The two outer layers of the polymer material (A) effectively insulate the second polymer material from the heat-exposed surfaces of the die 400, especially at the die outlet 410, which otherwise would cause die fouling of the second polymer material. Thus, in this arrangement, the extrusion method and extruded product advantageously provide a reduced die fouling compared to similar processes and products.

[0178] Figure 5a An extrusion apparatus 500 for producing an extruded film is shown. The apparatus includes a die body 1 and a co-extrusion feed block 2. The co-extrusion feed block 2 has a first channel 501, a second channel 502, and a third channel 503. Under pressure, the first and second channels are used to supply molten polymer material A and the third channel supplies polymer material B. These polymer materials are co-extruded through the co-extrusion feed block and then delivered to the die 1 for shaping into a film of a desired thickness. The molten polymer material A from the channel 501 forms the first outer layer 511 of the film, the molten polymer material A from the channel 502 forms the second outer layer 512, and the molten polymer material B from the channel 503 forms the inner layer 513, as Figure 5b shown in [Figure 0].

[0179] As in the embodiment described above, only the outer layers of the polymer material A of the film contact the co-extrusion feed block 1 and the die 2, and thus, due to the reduced tendency of the polymer material (A) to form die fouling, die fouling formation is reduced.

[0180] Figure 6aDisclosed is a die 600 for producing a filament extrusion product. The die 600 is formed by a die body 1 and a die mandrel 2. The die 600 includes a first channel 601, a second channel 602, and a die outlet 610. The first and second channels are used to supply molten polymer materials A and B under pressure. The molten polymer material A forms an outer layer 611 of the filament having the composition described above for the polymer material (A), and the molten polymer material B forms an inner layer or core 612 of the filament, as Figure 6b shown. The molten polymer material B is suitably the polymer material (B) as described above and suitably includes a filler material.

[0181] As in the embodiments described above, only the outer layer of the polymer material A of the filament contacts the thermally exposed surface of the die 600, and thus, due to the lower tendency of the polymer material (A) to form die fouling compared to the polymer material (B) of the composition, especially when the polymer material B includes a filler material, die fouling formation is reduced. The filaments produced in this way can be used as raw materials in additive manufacturing.

[0182] Examples

[0183] The following extrusion products were produced to demonstrate the reduction of die fouling achievable by the present invention.

[0184] The method involves the process steps of polymer drying followed by extrusion into a solid form, during which die fouling is compared for various polymers and configurations. Examples of solid forms include polymer filaments, flat wires with a polymer coating, and co-extruded round wires with multiple polymer coatings.

[0185] Polymer drying

[0186] Before extrusion, the powder / granules of each polymer material described below and used in the following methods were dried to less than 0.05% w / w moisture (dew point of -40 °C) by placing the material in an air-circulation oven at 150 °C for at least 3 hours or at 160 °C for 2 hours. For LMPAEK TM materials, the preferred drying time is 2 - 3 hours at 120 °C. To ensure that the materials are sufficiently dry, the moisture content can be measured according to ISO 15512 method (B) and ISO 1133. Drying prevents voids from being formed in the extrudate due to the hygroscopicity of the polymer materials in powder or granule form after extrusion.

[0187] It should be understood that any mention of unfilled PEEK (Victrex 381G) in any of the following examples includes, but is not limited to, PEEK manufactured according to WO2018055384.

[0188] Example set 1 - Filaments

[0189] Filaments are produced by continuously extruding a molten polymeric material in order to assess the relative rate at which these polymeric materials form die build-up.

[0190] Example 1.1 - A PEEK polymeric material manufactured by Victrex Manufacturing Limited and designated as 381TL30, as defined herein, containing 30 wt% of a material filled with talc (JETFINE TM 3CA).

[0191] Example 1.2 - An unfilled PEEK material manufactured by Victrex Manufacturing Limited and designated as 381G.

[0192] Example 1.3 - A PEEK / PEDEK copolymer, manufactured by Victrex Manufacturing Limited according to EP3013888, as an LMPAEK TM material.

[0193] Method for producing filaments

[0194] Filaments are produced by introducing a pre-dried polymeric material into a typical single-screw extrusion line, which consists of a heated extruder barrel with a screw and the following zones: a feed zone, a compression zone, a metering zone, and a die zone, each having a temperature between 300 °C and 390 °C (see Table 1). The polymeric material is fed through the zones to produce a molten filament at the die exit.

[0195] The molten filament is withdrawn from the die and cooled to below the melting point of the polymeric material to freeze the filament into its final form.

[0196]

[0197] Table 1: Zone Temperatures (°C)

[0198] The inner diameter of the extruder barrel is between 15 mm and 50 mm, where the length-to-diameter ratio (L / D) of the screw is between 16:1 and 28:1, and preferably between 18:1 and 24:1. The line speed is set to 8 to 8.5 m / min.

[0199] Typically, the screw speed is set between 15 and 25 rpm. The screw speed can vary in the range of 3 to 50 rpm, preferably 4 to 30 rpm, and optimally 5 to 30 rpm. The line speed can vary between 1 and 30 m / min, preferably 3 to 25 m / min, and optimally 4 to 20 m / min.

[0200] The melt pressure during extrusion is measured using a pressure transducer that can be placed at the end of the screw or within the die. The melt pressure can vary depending on the material type and speed, but typically ranges from 2 bar up to 500 bar.

[0201] The molten polymeric material flows through the die via an extrusion line, which has a circular opening with a diameter of approximately 4 mm. The molten material is drawn out of the die and cooled in air at ambient temperature until below the melting point of the material. A caterpillar-type haul-off is used to draw the frozen filaments to the desired thickness. Filaments of approximately 1.5 to 2 mm, typically 1.7 mm, are produced by this process.

[0202] The size and shape of the die opening can vary. For example, the diameter of the opening can be from 0.2 mm to 8 mm and can have a square, rectangular, or leaf-shaped profile depending on the desired cross-sectional shape of the extruded product. The length of the die opening is suitably in the range of 0.1 to 6 times the diameter of the extruded filament, where the inlet section is preferably smooth with a consistent diameter change, although a stepped diameter change is also possible.

[0203] The filament is extruded through the extrusion line until die build-up is visible around the die opening and this die build-up starts to adversely affect the quality of the extruded product. Such adverse effects on the quality of the extruded product include visible marks and defects in the surface of the extruded product. Thinning of the diameter of the extrudate material and typically a reduction in diameter or thickness of greater than 15% is detrimental to product quality. An amount less than 15% should be understood as acceptable to a person of ordinary skill in the art. Additionally, carbonaceous die build-up that separates from the die and attaches to the extrudate can have an adverse effect on the quality of the final product. For different polymer materials, the time elapsed from the start of extrusion until the moment of adverse die build-up formation is detailed in Table 2.

[0204]

[0205] Table 2

[0206] The results in Table 2 show that the PEEK / PEDEK material provides a significant improvement in terms of the time elapsed before die build-up formation, compared to using a filled PEEK material or PEEK alone, which die build-up formation leads to visible defects along the length of the extrudate. Thus, the extrusion process of the present invention can run for a long time before the process must be stopped and the extrusion equipment cleaned. Advantageously, the process results in a more efficient production process and subsequently longer product lengths.

[0207] Example 2 - Coated copper wire

[0208] The coated wire is formed by extruding the polymeric material described in Table 2 above as a single layer onto the copper wire. Similarly, the process uses the continuous extrusion of the molten polymeric material onto the wire to evaluate the relative rate of die fouling formation of the polymeric material.

[0209] The coated wire is extruded through a clean extrusion die until significant die fouling is visible around the die opening and the die fouling begins to adversely affect the quality of the extruded product. Such adverse effects on the quality of the extruded product include visible marks and defects in the surface of the extruded product. The time elapsed from the start of extrusion until the moment of die fouling formation is recorded and provided in Table 3 for different polymeric materials. The coated wire is produced using the methods and equipment described below.

[0210] Method - Coated electric wire

[0211] The coated wire is produced using an extrusion line having a barrel diameter ratio and a wire speed as described above for Example 1. Typically, the screw speed is set between 2 and 10 rpm. To produce the coated wire, the extrusion line is configured with a crosshead die in which the molten polymeric material enters from one side of the line. Such a configuration allows the polymeric material to contact the wire within the die and form a sheath thereon. This type of extrusion process can be referred to as a "pressure" or "pressure die" system. In this example, the wire is a copper wire having a rectangular cross-section. The wire is continuously fed through the extrusion line and the polymeric material is extruded onto the wire in a continuous process. The wire speed is set at 8 to 8.5 m / min.

[0212] The cross-sectional shape of the wire can vary, for example, square or rectangular shape. The rectangular wire can have an aspect ratio of up to 4:1.

[0213] The gap between the uncoated wire and the die opening is typically between 50 microns and 300 microns. The final coated wire has a thickness between 100 and 200 microns.

[0214] Table 3 below shows the results of the time to die fouling formation.

[0215]

[0216] Table 3

[0217] The results in Table 3 show the time when the use of PEEK / PEDEK material in contact with the extrusion die during the extrusion process as a single polymer layer on the wire increases until significant die fouling occurs and begins to adversely affect the quality of the extruded product. In contrast, filled and unfilled PEEK materials show more rapid die fouling formation than PEEK / PEDEK materials. Thus, the use of PEEK / PEDEK enables the extrusion process to continue for a longer period before the extrusion equipment needs to be stopped and cleaned. This can provide a more efficient production process and longer extruded products.

[0218] Example 3 - Coextrusion on an electric wire

[0219] Having an inner and outer coating of the polymer material as Figure 1a and Figure 1b shown in the wire is formed by extruding the polymer materials indicated in Table 4 below as the outer and inner layers onto the copper wire. Similarly, the process uses continuous extrusion of the molten polymer material onto the wire to evaluate the relative rate of die fouling formation of these polymer materials.

[0220]

[0221] Table 4

[0222] As described above regarding Figure 1a and Figure 1b the coated wire is extruded through the clean extrusion die again until die fouling is visible around the die opening and the die fouling begins to adversely affect the quality of the extruded product. These adverse effects on the quality of the extruded product include visible marks and defects in the surface of the extruded product. The time elapsed from the start of extrusion until the moment when die fouling leading to the quality defects described above is formed is recorded, and the times are provided in Table 5 for different polymer materials. The coated wire is produced using the methods and equipment described below.

[0223] Using the extrusion line described above, a coated wire is produced with a second heated extruder barrel for the second polymer material. The extrusion die used is of the type Figure 1a shown in, configured for a "pressure" extrusion process, where the polymer materials of the outer and inner layers form a sheath on the wire within the die, with the outer layer contacting the die when the product exits and the inner layer contacting the wire in the product. The polymer materials indicated in Table 4 are extruded through the first channel 101 and the second channel 102 as described previously and shown in the drawings to form the outer and inner layers on the wire respectively.

[0224]

[0225] Table 5

[0226] The results in Table 5 show that, compared with similar filled or unfilled PEEK materials, the multilayer extrusion product of the polymeric material (A) which is a PEEK / PEDEK copolymer as claimed in the present invention (which is used as an outer layer coating on the surface contacting the die when leaving the extrusion die) can significantly increase the time until die fouling occurs and starts to adversely affect the quality of the extrusion product. Using the PEEK / PEDEK material as the outer layer provides approximately a 12-fold improvement in terms of the time elapsed before significant die fouling occurs compared to using a filled PEEK material as the outer layer.

[0227] Advantageously, the extrusion process for forming a product containing PEEK / PEDEK can continue for a longer period before the process needs to be stopped and the extrusion equipment cleaned, which can provide a more efficient production process. Additionally, the process can operate at higher outputs or line speeds that would typically exacerbate die fouling. Thus, in addition to product quality, productivity is also improved. Therefore, such extrusion products with an inner layer containing a PEEK polymer and a filler material can be formed, and the polymer and filler material do not form excessive die fouling that would adversely affect the process and the product.

[0228] It will be apparent to those of ordinary skill in the art that, as described herein and as illustrated in the accompanying drawings, the benefits seen in the above embodiments can also be applied to other wire coating embodiments, and can also be applied to embodiments of multilayer films and tubes.

[0229] Although several preferred embodiments have been shown and described, those of ordinary skill in the art should understand that various changes and modifications can be made without departing from the scope of the present invention, as defined in the appended claims.

[0230] Throughout this specification, the term "comprising" or "comprises" means including the specified components, but should not exclude the presence of other components. The term "consisting essentially of" or "consists essentially of" means including the specified components, but excluding other components, except for materials that appear as impurities, unavoidable materials present due to the processes used to provide such components, and components added for purposes other than achieving the technical effects of the present invention. Typically, when referring to a composition, a composition consisting essentially of a group of components will contain less than 5% by weight, typically less than 3% by weight, and more typically less than 1% by weight of non-specified components.

[0231] The term "consisting of" or "consists of" means including the specified components, but excluding the addition of other components.

[0232] In appropriate cases, as the case may be, the use of the term "comprises" or "comprising" may also be regarded as covering or including the meaning of "consists essentially of" or "consisting essentially of", and may also be regarded as including the meaning of "consists of" or "consisting of".

[0233] To avoid doubt, where the amount of a component in a composition is described in wt%, this means the weight percentage of the specified component relative to the entire composition mentioned. For example, "polymer material (A) provides 70 to 100 wt% of the outer layer" means that 70 to 100 wt% of the outer layer is provided by polymer material (A).

[0234] The optionally selected features described herein can be used individually or, where appropriate, in combination with each other, and especially in the combinations set forth in the appended claims. The optionally selected features of the aspects or exemplary embodiments of the invention as described herein should also be understood to be applicable, where appropriate, to any other aspect or exemplary embodiment of the invention. In other words, those of ordinary skill in the art reading this specification should regard the optionally selected features of the various exemplary embodiments of the invention as interchangeable and combinable between different exemplary embodiments.

[0235] It should be noted that all texts and documents filed simultaneously with or before this application and made available to the public for inspection by this specification, and the contents of all such texts and documents, are incorporated herein by reference.

[0236] All features disclosed in this specification (including any appended claims and drawings) and / or all steps of any method or process so disclosed can be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive.

[0237] Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims and drawings) may be replaced by alternative features that achieve the same, equivalent or similar purpose. Therefore, unless otherwise expressly stated, each disclosed feature is only one example of a series of generally equivalent or similar features.

[0238] The present invention is not limited to the details of the foregoing embodiments. The present invention extends to any novel feature or any novel combination of features disclosed in this specification (including any accompanying claims and drawings), or to any novel step or any novel combination of steps of any method or process so disclosed.

Claims

1. An extruded product comprising a first layer and a second layer; wherein the first layer comprises a polymeric material (A), the polymeric material (A) having: Repeating units of the following formula: -O-Ph-O-Ph-CO-Ph-I And repeating units of the following formula: -O-Ph-Ph-O-Ph-CO-Ph-II Wherein Ph represents a phenylene moiety.

2. The extruded product according to claim 1, wherein the first layer is the outer layer and the second layer is the inner layer.

3. The extruded product according to claim 1 or 2, wherein the second layer comprises a filler material.

4. The extruded product according to any one of the preceding claims, wherein the filler material is a particulate filler material.

5. The extruded product according to any one of the preceding claims, wherein the second layer comprises a polymeric material (B) having repeating units of the following formula: -O-Ph-O-Ph-CO-Ph-I Wherein Ph represents a phenylene moiety.

6. The extruded product according to any one of the preceding claims, comprising a third layer; wherein the second layer is disposed between the first layer and the third layer; and wherein the third layer comprises a polymeric material (A), the polymeric material (A) having: Repeating units of the following formula: -O-Ph-O-Ph-CO-Ph-I And repeating units of the following formula: -O-Ph-Ph-O-Ph-CO-Ph-II Wherein Ph represents a phenylene moiety.

7. The extruded product according to any one of the preceding claims, wherein the first layer and / or the third layer comprises a release agent.

8. The extruded product according to any one of the preceding claims, wherein the extruded product is in the form of a film.

9. The extruded product according to any one of claims 1 to 7, wherein the extruded product is in the form of a tube or a cable jacket / sheath.

10. The extruded product according to any one of claims 1 to 7, wherein the extruded product is in the form of a filament.

11. The extruded product according to any one of the preceding claims, wherein the polymeric material (A) has: Repeating units of formula Ia: and Repeating units of formula IIa: Wherein at least 95 mol% of the repeating units are repeating units of formula Ia and formula IIa; Wherein the molar ratio of repeating units Ia:IIa is from 50:50 to 95:

5.

12. The extruded product according to any one of claims 1 to 10, wherein the polymeric material (A) consists essentially of the following Composition: Repeating units of formula I: -O-Ph-O-Ph-CO-Ph-I; Repeating units of formula IIa: And end units; Wherein the molar ratio of the repeating units of formula I to the repeating units of formula IIa is from 50:50 to 95:5; and Wherein the repeating units of formula I consist essentially of the following: 50 to 90 mol% of repeating units of formula Ia: And 10 to 50 mol% of repeating units of formula Ib, formula Ic or a mixture thereof; Wherein the repeating units of formula Ib are: and The repeating units of formula Ic are:

13. A method of producing a product comprising a first layer and a second layer, the method comprising the steps of: a) Provide a source of a polymeric material (A), the polymeric material (A) having: Repeating units of the formula: -O-Ph-O-Ph-CO-Ph-I and repeating units of the formula: -O-Ph-Ph-O-Ph-CO-Ph-II wherein Ph represents a phenylene moiety; b) Provide a source of a second polymeric material; c) Deliver the polymeric material (A) and the second polymeric material to an extrusion table comprising a die; d) Extrude the polymeric material (A) and the second polymeric material via the die such that the polymeric material (A) contacts the die during extrusion and the second polymeric material does not contact the die during extrusion to form the extruded product.

14. The method according to claim 13, wherein the second polymeric material comprises a filler.

15. The method according to claim 13 or claim 14, wherein the method is carried out for at least 5 hours, preferably at least 10 hours.

16. Use of a polymeric material (A) for reducing the formation of deposits on the die of an extrusion apparatus during extrusion of a second polymeric material; wherein the polymeric material (A) has: Repeating units of the formula: -O-Ph-O-Ph-CO-Ph-I and repeating units of the formula: -O-Ph-Ph-O-Ph-CO-Ph-II wherein Ph represents a phenylene moiety.

17. The use according to claim 16, wherein the polymeric material (A) is arranged as an outer layer on the second polymeric material.

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