WO2024105278A1

WO2024105278A1 - Copolyester, compositions and methods

Info

Publication number: WO2024105278A1
Application number: PCT/EP2023/082445
Authority: WO
Inventors: Wilhelmus Petrus Johannes APPEL; Ard Jan KOLKMAN; Franciscus Josephus Mauritius Souren
Original assignee: Dsm Ip Assets B.V.
Priority date: 2022-11-18
Filing date: 2023-11-20
Publication date: 2024-05-23

Abstract

The invention relates to copolyester comprising hard segment H comprising at least one monomeric unit of Formula (1), soft segment S comprising at least one monomeric unit of Formula (2), and segment D comprising at least one monomeric unit of Formula (3), with wherein t is 1 or 2; b1 and b2 are independently chosen from polyethylene oxide (PEO) having m1 repeat units, polypropylene oxide (PPO) having m2 repeat units, or combinations thereof, wherein the number average values of m1 and m2 are independently selected from 0, in case not present, or from 2 to 50, wherein m1+m2=m and m is from 2 to 50; A is (4), wherein the number average value of p is from4 to 100; R1 and R2 are substituents independently chosen from alkyl, aralkyl and aryl; R3 and R4 are substituents independently chosen from one or more linear alkylene groups, one or more branched alkylene groups, one or more arylene groups, or combinations thereof; R5 is a polymer chosen from polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of polyethylene oxide and polypropylene oxide, linear aliphatic polycarbonates, polybutylene adipate (PBA) and derivates of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters and combinations thereof; wherein the amount of segment D is between 0.1 and 60 wt% and the total amount of segments H, S and D is at least 90 wt% wherein wt% is with respect to the total mass of copolyester, and wherein the number average molecular weight of the copolyester is at least 10 000 g/mol. The invention further relates to methods for preventing squeak employing the copolyester or compositions thereof.

Description

COPOLYESTER, COMPOSITIONS AND METHODS

Field of Invention

The present invention relates to a copolyester and compositions thereof, and methods for preventing squeak employing the copolyester or compositions thereof.

Copolyesters are known and are used in a wide area of applications. Copolyesters combine properties such as dimensional stability with good elastomeric properties. However, noise, also known as squeak, can occur when a copolyester surface rubs against another surface, which is undesirable. This is particularly observed under wet conditions.

Squeak is often observed in constant-velocity joint (CVJ) boots, which are used to protect constant velocity joints (CV joints) in vehicles. The boot protects the CV joint from penetration of moisture and contaminants into the CV joint. Thermoplastic polyester elastomers are generally used to produce the boot, since these provide a long life under all kind of climate conditions. However, a problem of a CVJ boot formed from a thermoplastic polyester elastomer is that it squeaks when the car is being driven. It is believed that the noise is caused by the rubbing of the flanges of the boot against each other, and is especially noted under wet conditions. The occurrence of the squeak is becoming increasingly problematic because the motors of modern cars are more and more silent, so that the noise caused by the boots of the CV joints becomes more and more notable.

Squeak may also be observed in other situations where surfaces of the article come into contact with each other or other materials during use, such as mattresses made from a 3D structure of fused monofilaments or shoe (mid-)soles, which are often made from copolyesters. In such applications, noise such as squeak is very noticeable.

Attempts have been made to reduce squeak by adding a wax to the polymer composition. Over time, these waxes migrate to the surface of the composition, preventing squeak during use. However, although a considerable initial noise reduction was obtained initially, over time the wax is lost squeak occurs again. For CVJ boots, this occurs after and after about 1-3 years of driving. Since the wax modifies the mechanical properties of the composition, the amount of wax that can be blended with the copolyester is limited whilst retaining the desired properties. In particular, a higher amount of wax results in a slippery surface of a CVJ boot, which prevents mounting of the boot. It even may cause problems in the production process of the boots.

Therefore, it is not possible to increase the amount of wax in the composition in order to increase the anti-squeak lifetime.

Therefore, there is a need for copolyesters that prevent squeak, while retaining the desired mechanical properties. There is also a need for copolyesters that allow for squeak to be reversed once it occurs.

Articles comprising copolyesters are known and are used in a wide area of applications. Copolyesters are often employed in applications in which surface properties are very important. Surface properties of molded articles relate to mold sticking, and the replication of the surface texture of the mold. Surface properties are critical in determining the frictional characteristics of a surface which may affect scratch and abrasion properties as well as the feel of the material. Copolyesters preferably also withstand staining. To improve surface properties of the articles comprising copolyester, additives which change the surface properties can be added, for example to modify the water contact angle to improve stain resistance. The downside of adding surface modifying additives as blends is that they are often incompatible, which may result in non-homogeneous distributions, sensitivity to flow history of the material and in extreme cases can result in delamination of surfaces. Similarly, plasticizers are often added to provide extra softness to the material, but plasticizers may leach to the surface and may modify the mechanical properties of the composition.

Therefore, it is also desirable to provide a copolyester which exhibits sufficient surface properties in combination with sufficient mechanical properties.

Another problem that is observed is that, for very soft grades of copolyester, thus with high elastomeric properties, granules comprising the copolyester may stick to each other. This is also referred to as agglomeration or blocking. This has as disadvantage that the granules are difficult to dose and transport in order to proceed with processing. One solution to prevent sticking is to perform granulation of the copolyester by underwater granulation. This at least temporarily reduces blocking of the granules. However, if the granules are stored for longer times, blocking may still occur.

Therefore, it is also desirable to provide a copolyester which exhibits less sticking.

Summary It has surprisingly been found that squeak can be prevented by employing a copolyester or composition according to the present invention. It has also surprisingly been found that squeak may be reversed by drying the copolyester or composition according to the present invention. Accordingly the present invention provides a copolyester comprising hard segment H comprising at least one monomeric unit of Formula (1 ), and soft segment S comprising at least one monomeric unit of Formula (2), wherein the copolyester further comprises segment D comprising at least one monomeric unit of Formula (3), with

Formula (2)

Formula (3) wherein t is 1 or 2; b¹ and b² are independently chosen from polyethylene oxide (PEO) having m¹ repeat units, polypropylene oxide (PPO) having m² repeat units, or combinations thereof, wherein the number average values of m¹ and m² are independently selected from 0, in case not present, or from 2 to 50, wherein m¹+m²=m and m is from 2 to 50;

wherein the number average value of p is from 4 to 100;

R¹ and R² are substituents independently chosen from alkyl, aralkyl and aryl;

R³ and R⁴ are substituents independently chosen from one or more linear alkylene groups, one or more branched alkylene groups, one or more arylene groups, or combinations thereof;

R⁵ is a polymer chosen from polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of polyethylene oxide and polypropylene oxide, linear aliphatic polycarbonates, polybutylene adipate (PBA) and derivates of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters and combinations thereof; wherein the amount of segment D is between 0.1 and 60 wt% and the total amount of segments H, S and D is at least 90 wt% wherein wt% is with respect to the total mass of copolyester, and wherein the number average molecular weight of the copolyester is at least 10 000 g/mol.

The number average molecular weight of the copolyester may be measured with size exclusion chromatography in hexafluoroisopropanol at 40 °C. Size exclusion chromatography measurements are performed as follows on a Viscotek GPC Max (System ID: LT-8) equipped with Viscotek Triple Detector Array 305 at 40°C, including ultra-violet (UV), refractive index (Rl), differential viscometer (DV), and right-angle lightscattering (RALS) detector. As solvent, hexafluoroisopropanol (HFIP) is used. For separation, HFIP-compatible columns may be used: three Polymer Standards Service (PSS) PFG Linear XL 7 pm, 300 x 8.0 mm columns with guard-column 7pm, 50mm x 8.0 mm. Flow rate may be 0.8 ml/min. Prior to size exclusion chromatography analysis, the sample is dissolved by weighing approximately 30 mg and adding approximately 20 ml HFIP (polymer concentration » 1 .5 mg/ml) and gently shaking for 4 hours at room temperature. The solution is filtrated (0.2 pm PTFE), and the obtained solution is analysed by size exclusion chromatography. The refractive index increment (dn/dc) is determined from the obtained data and used for calculation for the number average molecular weight of the copolyester.

Preferably b¹ and b² are polyethylene oxide (PEO) thus with m² being 0, or polypropylene oxide (PPO) thus with m¹ being 0. More preferably, b¹ and b² are polyethylene oxide (PEO) thus with m² being 0.

Preferably, b¹+b²=B and the number average molecular weight ratio of A:B is from 3:1 to 1 :3.

Preferably, the amount of segment D is between 0.5 and 50 wt%, more preferably between 5 and 40 wt %, even more preferably between 10 and 30 wt%, most preferably between 15 and 25 wt%, wherein wt% is with respect to the total mass of copolyester.

Also provided is a copolyester composition comprising the copolyester as defined herein.

The preset invention further provides an article comprising the copolyester or copolyester composition as defined herein.

Additionally provided is a method of reducing or preventing squeak when two or more surfaces move against one another, the method comprising forming at least one the surfaces from the copolyester or the composition according to the present invention. Surprisingly, it has been found that copolyesters and compositions according to the present invention provide sufficient surface properties in combination with sufficient mechanical properties, which is demonstrated by contact angle measurements.

It has also been surprisingly found that the granules formed by the copolyester or composition according to the present invention also exhibit less sticking, while the mechanical properties of the copolyester are retained. This is particularly evident at a relatively low amount of segments D.

Detailed Description

Reference to % herein, e.g. with respect to the amounts of different segments, is intended to refer to wt.%, unless made clear that another definition is intended.

“Precursor” refers to a molecule that, after reaction with another precursor forms a unit of a segment. Usually a precursor contains hydroxyl or carboxylic acid or carboxylic ester end groups to allow sufficient reactivity to form a unit of a segment.

“At least one monomeric unit” is hereby defined as the smallest repeating unit of a segment.

Reference to a value of “from” a first value “to” a second value is intended to refer to any value within the range defined by the first value and the second value, including the first value and the second value.

The copolyester according to the present invention comprises: hard segment H comprising at least one monomeric unit of Formula (1 );

- soft segment S comprising at least one monomeric unit of Formula (2); and

- segment D comprising at least one monomeric unit of Formula (3), where Formulas (1 ), (2) and (3) are as defined herein.

The amount of segment D is between 0.1 and 60 wt% and the total amount of segments H, S and D is at least 90 wt% wherein wt% is with respect to the total mass of copolyester. The number average molecular weight of the copolyester is at least 10 000 g/mol. This may be measured by size exclusion chromatography in hexafluoroisopropanol at 40 °C. Hard segment H

The copolyester comprises hard segment H comprising at least one monomeric unit as denoted by Formula (1 ):

Formula (1) wherein t is 1 or 2. Preferably, the hard segment H consists of monomeric units as denoted by Formula (1)-

Preferably t is 2. Preferably, the at least one monomeric unit of hard segment H comprise terephthalate and/or isophthalate units derived from precursors terephthalic acid and/or isophthalic acid, respectively, or derivatives thereof, as well as ethylene (t=1) and/or butylene (t=2). Thus, hard segment H preferably comprises monomeric units of Formula (11), Formula (1 i), or combinations thereof:

Formula (11)

Preferably, the at least one monomeric unit of hard segment H is derived from terephthalic acid or any derivative thereof that leads to terephthalate and t is 1 or 2, and thus is denoted by Formula (1t). If t is 1 , the hard segment H is also referred to as polyethylene terephthalate (PET). If t is 2, the hard segment is also referred to as polybutylene terephthalate (PBT), as shown in Formula (1a):

Formula (1a)

The hard segments H may be a combination of PBT and PET.

Alternatively, the at least one monomeric unit of hard segment H may be derived from isophthalic acid or any derivative thereof that leads to isophthalate and t is 2, as shown in Formula (1b):

Formula (1b) The hard segment H may comprise monomeric units derived both from isophthalic acid and terephthalic acid or any derivatives thereof and where t=2, which leads to a copolyester comprising hard segment H comprising monomeric units of Formula (1a) and Formula (1b).

Most preferably, the hard segment H comprises monomeric units derived from terephthalic acid or any derivative thereof and t is 2. Thus, the hard segment H is preferably PBT, as denoted by Formula (1a). This hard segment H has the advantage of high melt stability and compatibility with a large variety of soft segments S to make various copolyesters with wide ranging physical properties. The copolyester may comprise hard segment H consisting of monomeric units as denoted by Formula (1a).

The amount of hard segments H is preferably between 15 and 90 wt %, more preferably 20 and 80, and most preferably between 25 and 70 wt %, in which wt % is based on the total mass of the copolyester. The exact amount of hard segments H can be tailored depending upon the desired properties of the copolyester, such as the desired hardness of the copolyester.

Soft segment S

The copolyester comprises soft segment S comprising at least one monomeric unit denoted by Formula (2):

Formula (2) wherein R⁵ is a polymer chosen from polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of polyethylene oxide and polypropylene oxide, linear aliphatic polycarbonates, polybutylene adipate (PBA) and derivates of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters and combinations thereof. An example of suitable linear aliphatic polycarbonates is polyhexamethylene carbonate (PHMC).

Preferably, soft segment S consists of monomeric units denoted by Formula (2).

Preferably, the soft segment S comprises monomeric units derived from precursors terephthalic acid and/or isophthalic acid, or derivatives thereof, as well as a unit denoted by R⁵. Thus, soft segment S preferably comprises monomeric units of Formula (2t), Formula (2i), or combinations thereof:

Formula (2i)

R⁵ preferably has a molar mass of from 500 g/mol to 8000 g/mol, more preferably from 1000 to 7000 g/mol, most preferably from 1500 to 6500 g/mol. The molar mass can be measured according to size exclusion chromatography or ¹H nuclear magnetic resonance (NMR) spectroscopy.

Preferably R⁵ is chosen from the group consisting of PTMO, PEO, PPO, PEO-PPO- PEO triblock copolymer, derivatives of dimer fatty acid and/or diol, and any combinations thereof, as these essentially contribute pliability, elasticity, thermal stability, oxidative stability, and a host of other properties. Preferably, R⁵ is chosen from the group consisting of PTMO, PEO, PPO, PEO-PPO-PEO triblock copolymer, which would have Formulas (2e) to (2g) respectively. Most preferably, R⁵ is PTMO, as shown in Formula (2e).

Formula (2e) wherein x denotes the number of PTMO repeat units. The number average value of x is preferably from 10 to 45.

Formula (2f) wherein y denotes the number of PEO repeat units. The number average value of y is preferably from 15 to 150.

Formula (2g) wherein v denotes the number of PEO repeat units and w denotes the number of PPO repeat units. The number average value of v is preferably from 2 to 30 and the preferred number average value of w is from 5 to 50. The preferred number average value of 2v+w is from 9 to 110.

Preferably, soft segment S comprises at least one monomeric unit denoted by Formula (2t) or Formula (2i) wherein R⁵ is PTMO, PEO, PPO or PEO-PPO-PEO triblock copolymer, wherein R⁵ has a molar mass of from 500 g/mol to 8000 g/mol. Monomeric units of segment S preferably have the structure of Formula (2a), (2b), (2c) and/or (2d), wherein R⁵ in Formula (2a) denotes PTMO with various molecular weights, denoted by x. R⁵ in Formulas (2b) and (2c) denotes PEO with various molecular weights, denoted by y and z respectively. R⁵ in Formula (2d) is PEO-PPO-PEO triblock copolymer, with various molecular weights, denoted by v and w for PEO and PPO blocks respectively. The preferred number average value of x is from 10 to 45. The preferred number average values of y and z are each independently from 15 to 150. The preferred number average value of v is from 2 to 30 and the preferred number average value of w is from 5 to 50. The preferred number average value of 2v+w is from 9 to 110.

Formula (2d)

Preferably, the amount of soft segments S is between 20 and 80 wt%, preferably between 25 and 75 wt%, and most preferably between 30 and 72 wt%, in which wt% is based on the total mass of the copolyester. A higher amount of soft segments S results in a softer copolyester and has the advantage that the resulting copolyester has enhanced flexibility, elasticity, and yet retains strength for example relatively high tensile modulus combined with high elongation at break.

Segment D

The copolyester comprises segments D comprising at least one monomeric unit denoted by Formula (3):

Formula (3) wherein b¹ and b² are chosen from polyethylene oxide (PEO) having m¹ repeat units, polypropylene oxide (PPO) having m² repeat units, or combinations thereof, wherein the number average values of m¹ and m² are independently selected from 0, in case not present, or from 2 to 50, wherein m¹+m²=m and m is from 2 to 50;

wherein the number average value of p is from 4 to 100;

R¹ and R² are substituents independently chosen from alkyl, aralkyl and aryl;

R³ and R⁴ are substituents independently chosen from one or more linear alkylene groups, one or more branched alkylene groups, one or more arylene groups, or combinations thereof.

Preferably, the copolyester comprises segments D consisting of monomeric units denoted by Formula (3).

Preferably R¹ and R² are substituents independently chosen from alkyl groups or phenyl groups, more preferably R¹ and R² are substituents independently chosen from methyl, ethyl, propyl, benzyl and aryl, and most preferably R¹ and R² are methyl groups, i.e. -CH₃. Preferably, R¹ and R² are the same substituent, thus R¹=R².

R³ and R⁴ are substituents independently chosen from one or more linear alkylene groups, one or more branched alkylene groups, one or more arylene groups, or combinations thereof. Thus, R³ and R⁴ may be independently selected from linear alkylene groups, branched alkylene groups or arylene groups. R³ and R⁴ may also be independently selected from the combination of one or more of: one or more linear alkylene groups, one or more branched alkylene groups, and/or one or more arylene groups. Preferably, R³ and R⁴ are substituents independently chosen from linear alkylene groups, more preferably R³ and R⁴ are substituents independently chosen from methylene, ethylene, propylene, benzylene, or combinations thereof, most preferably R³ and R⁴ are propylene, i.e. -(CH₂)3-. Preferably, R³ and R⁴ are the same substituent, thus R³=R⁴. b¹ and b² are independently selected from polyethylene oxide (PEO) having m¹ repeat units, polypropylene oxide (PPO) having m² repeat units, or combinations thereof. The number average values of m¹ and m² are independently selected from 0, in case not present, or from 2 to 50. The combined value of m¹ and m² is m (i.e. m¹+m²=m), and the value of m is from 2 to 50. Preferably the number average value of m¹ and m² are independently selected from 0, in case not present, or from 2 to 20, more preferably the number average value of m¹ and m² are independently selected from 0, in case not present, or from 5 to 15 and even more preferred the number average value of m¹ and m² are independently selected from 0, in case not present, or from 8 to 12. Preferably the value of m is at least 2 and at most 20, more preferably the value of m is at least 5 and at most 15 and even more preferred the value of m is at least 8 and at most 12. Preferably, b¹ and b² are the same, thus b¹=b².

Preferably b¹ and b² are polyethylene oxide (PEO) or polypropylene oxide (PPO). Thus, preferably b¹ and b² are polyethylene oxide (PEO) having m¹ repeat units wherein the number average value of m¹ is at least 2 and at most 50, or polypropylene oxide (PPO) having m² repeat units, wherein the number average value of m² is at least 2 and at most 50. Here, m=m¹ or m². Therefore, in this embodiment b¹ and b² are polyethylene oxide (PEO) or polypropylene oxide (PPO) having m repeat units, wherein the number average value of m is at least 2 and at most 50. Thus, Formula (3) may also be depicted as shown below:

More preferably, b¹ and b² are polyethylene oxide (PEO). Thus, preferably b¹ and b² are polyethylene oxide (PEO) having m¹ repeat units wherein the number average value of m¹ is at least 2 and at most 50. Here, m=m¹. Therefore, in this embodiment b¹ and b² are polyethylene oxide (PEO) having m repeat units, wherein the number average value of m is at least 2 and at most 50. Thus, Formula (3) may be depicted as shown below:

wherein the number average value of p is from 4 to 100. Preferably the number average value of p is from 10 to 80, more preferably p is from 12 to 65. b¹+b²=B and preferably the number average molecular weight ratio of A:B is from 3:1 to 1 :3. Preferably, the number average molecular weight ratio of A:B is from 2:1 to 1 :2, more preferably 3:2 to 2:3, most preferably around 1 :1 .

The number average values of b¹, b², m¹, m² and p can be determined by ¹H NMR spectroscopy using known methods.

The values for m and p, and in particular the ratio of A:B, has the advantage that segments D are more compatible with the segments H and S, thus readily being covalently incorporated. Surprisingly, segment D may be homogeneously distributed during copolyester production and therefore quantitatively incorporated into the copolyester backbone structure, providing the optimal efficacy in anti-squeak action. This also allows the copolyester to provide good anti-stick properties. The at least one monomeric unit of segment D may be denoted by Formula (3a) and/or (3b), wherein R¹ and R² are methyl groups and R³ and R⁴ are propylene groups.

Formula (3b)

Polyesters comprising a segment similar to segment D are known in the art, and are for example disclosed in WO2010/114508 and in “Synthesis and Properties of poly(butylene terephthalate)-Poly(ethylene oxide)-Poly(dimethylsiloxane)Block copolymers”, Macromol. Symp. 2003, 199, 147-162. These polyesters, however, do not contain soft segments S. Polymers of Formula (3) are available commercially, for example hydroxyalkyl terminated poly(propyleneoxy)-polydimethylsiloxane block copolymer (CAS: 161755-53-9) is available from Cymit Quimica.

The at least one monomeric unit of segment D comprises isophthalate and/or terephthalate units derived from precursors isophthalic acid and/or terephthalic acid; or any derivatives thereof as well as units denoted by b¹, b², A, and R¹ to R⁴. Preferably, segment D comprises at least one monomeric unit derived from precursor terephthalic acid or a derivative thereof, for example as denoted by Formula (3a).

The amount of segments D in the copolyester is between 0.1 and 60 wt %, preferably between 0.5 and 50 wt %, more preferably between 5 and 40 wt %, even more preferably between 10 and 30 wt % and most preferably between 15 and 25 wt %, wherein wt % is with respect to the total mass of copolyester. It has been found that these amounts of D segment allow for squeak prevention, whilst also allowing for synthesis of the copolyester. Higher amounts of D segment were found to negatively impact the synthesis of the copolyester. Lower amounts of segment D were not found prevent squeak effectively. It has been found that the copolyester prevents squeak particularly well when the amount of segments D in the copolyester is between 10 and 30 wt %, preferably between 15 and 25 wt %, for example 20 wt%. Therefore, these amounts of segment D are preferred when optimal squeak prevention is desired.

It has surprisingly been found that segment D also results in anti-stick behavior in the copolyester. This anti-stick behavior is observed at relatively low amounts of segments D in the copolyester. Therefore, if polymers having anti-sticking behavior are desirable, lower percentages of D segment may be used, such as between 0.1 and 20 wt %, preferably between 0.5 and 10 wt % and more preferably between 1 .0 and 5 wt%, wherein wt % is with respect to the total mass of copolyester. It has been found that at these percentages, the copolyester prevents squeak, but also effectively prevents sticking. This is particularly observed in soft grades of copolyester, where the amount of soft block S is 50 wt% or greater, such as 50wt% to 80 wt%.

A copolyester with a relatively high amount of segment D can be employed in combination with a further copolyester not containing segment D, thus in a composition being a blend of at least two copolyesters. This has the advantage that the composition then may comprise segment D in a low amount with respect to the total mass of composition, while being dosed easily upon preparing the composition.

Segment D is incorporated covalently into the copolyester and, for the avoidance of doubt, is thus not present as a blend. With “incorporated covalently” is meant that the segment is part of the polymeric chain, in contrast to a blend, which denotes the result of mixing of two or more components, where substantially no interaction in the context of covalent molecular bonding is observed between the two or more components.

Preferably, the number average molecular weight of segment D is from 1000 to 6000 g/mol, more preferably from 1250 to 4000 g/mol, most preferably from 1500 to 3500 g/mol. This also has the advantage that segments D are more compatible with the segments H and S, thus readily being covalently incorporated. Thus, segment D may be homogeneously distributed during copolyester production and therefore quantitatively incorporated into the copolyester backbone structure, providing the optimal efficacy in anti-squeak action. This also allows the copolyester to provide good anti-stick properties. The number average molecular weight may be measured using Size Exclusion Chromatography. Size Exclusion Chromatography measurements may be performed as follows on a Viscotek GPCMax VE2001 solvent/sample module system, equipped with TDA302 triple detector array. For chromatographic separation, three PLgel mixed C Linear 5 pm, 300 x 7.5 mm are applied, including guard column. Detectors and columns are operated at 30°C. Prior to Size Exclusion Chromatography analysis, the polymer is dissolved/diluted at concentration ranging from 1 .0 to 2.0 mg/ml in tetrahydrofuran, which is also used as an eluent at a flow rate of 1 .0 ml/min. The molar mass and molar mass distribution are determined with conventional calibration, using the refractive index detector, based on Polyethylene Glycol (PEG) Easivials from Agilent. The standards cover the molar mass range 106 - 34520 Dalton. The molar mass parameters, like Mn, Mw, Mz, Mw/Mn, Mz/Mw, are calculated by setting integration limits at the beginning and the end of the refractive index chromatogram.

Copolyester

The copolyester according to the invention has at least three different types of segments H, S and D, which may be in various orders and lengths. The segments are randomly distributed among each polymer chain, and the number average molecular weight of the copolyester is at least 10000 g/mol. This may be measured by size exclusion chromatography in hexafluoroisopropanol at 40 °C.

Preferably the number average molecular weight of the at least one copolyester is at least 15000 g/mol, more preferably at least 20000 g/mol. A higher molecular weight has the advantage that mechanical integrity is enhanced and squeak behavior is further reduced. The maximum number average molecular weight of the copolyester is not particularly limited and may be as high as for example 40000, 50000 or 60000 g/mol and is usually limited by reactor capabilities in terms of mechanical stirring power. Thus, the number average molecular weight of the copolyester may be from 10000 to 60000 g/mol, preferably from 15000 to 50000 g/mol, and more preferably from 20000 to 40000 g/mol. This has an additional advantage in that the squeak behavior is further reduced. The copolyester can optionally be reacted further via solid state post-condensation in so-called tumble driers and/or by chain extension in a reactive extrusion set-up (compounding), preferably by solid state post-condensation, to increase the molecular weight. This has an additional advantage in that the squeak behavior is further reduced.

The total amount of segments H, S and D is at least 90 wt%, preferably at least 92 wt%, more preferably at least 95 wt%, even more preferably at least 97, most preferably at least 99 wt%, wherein wt% is with respect to the total mass of copolyester. The upper limit for the total amount of segments H, S and D is 100 wt%.

The copolyester may further contain minor amounts of other components such as additional monomeric units or branching agents such as trimellitate linkages derived from precursors such as for example trimethyl trimellitate, or any derivative thereof, which may be incorporated during production in minor amounts. Typically these other components may each be present in an amount of at most 10 wt %, more preferably in an amount at most 5 wt %, and most preferably at most 2 wt % based on the total mass of the copolyester. Preferably these other components are present in a combined amount of at most 10 wt %, amount at most 5 wt %, and most preferably at most 2 wt % based on the total mass of the copolyester. Preferably, the amounts of these other components in combination with the amount of segments H, S and D totals 100 wt% based on the total mass of the copolyester.

Preferably, the copolyester comprises:

- hard segment H comprising at least one monomeric unit of Formula (1t) and/or Formula (1 i):

Formula (1t)

Formula (1 i) wherein t is 1 or 2; - soft segment S comprising at least one monomeric unit of Formula (2t) and/or

Formula (2i):

Formula (2i) wherein R⁵ is PTMO, PEO or PEO-PPO-PEO triblock copolymer, wherein R⁵ has a molar mass not less than 500 g/mol and not more than 5000 g/mol; and

- segment D comprising at least one monomeric unit of Formula (3):

Formula (3) wherein b¹ and b² are polyethylene oxide (PEO) having m repeat units, wherein the number average value of m is from 2 to 50;

wherein the number average value of p is from 4 to 100;

R¹ and R² are methyl;

R³ and R⁴ are propylene; and wherein b¹+b²=B and the number average molecular weight ratio of A:B is from 3:1 to 1 :3, wherein the amount of segment D is between 5 and 60 wt% and the total amount of segments H, S and D is at least 80 wt% wherein wt% is with respect to the total mass of copolyester, and wherein the number average molecular weight of the copolyester is at least 10 000 g/mol as measured with size exclusion chromatography in hexafluoroisopropanol at 40 °C.

The copolyester may be prepared by polymerization reaction according to a variety of different methods, which are known per se to a person skilled in the art. Generally, the copolyester is prepared by mixing all precursors, either simultaneously or sequentially throughout the polymerization process, heating the mixture to a temperature until the mixture is in a molten state, such as for example at least 180 °C, preferably at least 200 °C, and even more preferred at least 220 °C. Preferably, the maximum temperature is 280 °C The reaction temperature is applied until the desired molecular weight of the copolyester is obtained, after which the copolyester is cooled and optionally granulated. The reaction temperature usually is at least as high as the melting temperature of the copolyester, as the copolyester generally remains in a molten state until the desired molecular weight is obtained. Preferably, the temperature is maintained under reduced pressure to remove condensate. Preferably the pressure is below 100 kPa, preferably from 0.01 Pa to 50 kPa. Preferably the precursors are terephthalic acid derivative such as dimethyl terephthalate and 1 ,4-butane diol; a precursor to unit R⁵ for example PTMO with hydroxyl end-groups; a precursor to segment D, a catalyst to promote condensation/esterification for example titanium tetrabutoxide; optionally a stabilizer for example 1 ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene (commercially available as Irganox 1330). Preferably, the mixture is heated under reduced pressure, the condensate(s) are removed from the reaction mixture while viscosity is monitored. Upon general increase in viscosity, the reaction can be stopped to target various properties, and the copolyester expelled from the reactor. The copolyester may be granulated and/or transported for further processing, for example solid state post-condensation or chain extension.

The target properties can include, but are not limited to, specific Shore D/Shore A hardness, elongation at break, tensile modulus, melt flow, melting points, water contact angles, anti or never squeak performance, or melt viscosity. The specific target properties can be achieved by modulating the relative weight fractions of the precursors of the various segments and the molar mass precursors of the S and D segments, and thus the copolyester according to the invention, and the final degree of polymerization.

The copolyester may have a shore A hardness of less than 100 as measured according to ISO 868:2003, more preferably at most 90 and even more preferred at most 85, and most preferred at most 82. The shore A hardness may be at least 50. This is measured at ambient temperature (23 °C +/- 1 °C). The inventors have found that especially with very soft grades, for example those having a shore A hardness of below 90, incorporation of the segment D resulted in minimization of blocking/agglomeration in addition to anti-squeak behaviour. The hardness of the copolyester may be influenced by the type of soft segments S and the total amount of soft segments S, as is generally known to a person skilled in the art. Composition

Another aspect of the invention provides a composition comprising the copolyester as described herein.

The composition preferably comprises at least 1 wt%, more preferably at least 5 wt% and even more preferred at least 10 wt% of the copolyester as described herein, wherein wt% is with respect to the total weight of the composition. The copolyester may be present in an amount from 1 wt% to 30 wt%, preferably 5 wt% to 25 wt%, more preferably 10 wt% to 20 wt%. In these low amounts, the copolyester serves as an additive and is usually combined with another thermoplastic polymer.

Preferably, the composition comprises at least 40 wt%, more preferably at least 50 wt%, and even more preferably at least 60 wt% of the copolyester as described herein, wherein wt% is with respect to the total weight of the composition. The copolyester may be present in an amount from 40 wt% to less than 100 wt%, preferably 50 wt% to 90 wt%, more preferably 60 wt% to 80 wt%. The composition may consist essentially of the copolyester. In these higher amounts, the copolyester significantly contributes to the mechanical properties of the composition, thus squeak is prevented more effectively.

The composition may comprise another component, such as: one or more additives, one or more additional polymers, and/or one or more waxes. Additional polymers include: thermoplastic polymers such as polyesters and polyamides; thermoplastic elastomers such as SEBS; soft thermoset elastomers such as soft rubbers; cross linked elastomers such as polydimethylsiloxanes; and hydrocarbon elastomers. Additives include: pigments such as carbon black; stabilizers such as UV stabilizers; catalysts; nucleating agents such as titanium tetrabutoxide; talcum; anti-oxidants such as 1 ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene (commercially available as Irganox 1330); fillers such as glass fibers and carbon fibers; flame retardants such as metal phosphinates and/or nitrogen containing and nitrogen/phosphor containing compounds; lubricants; and mold release agents.

Suitable nitrogen containing and nitrogen/phosphor containing compounds that can be used as flame retardant are described, for example in PCT/EP97/01664, DE-A-19734 437, DE-A-19737 72, and DE-A-196 14424. Suitable waxes include: microwaxes, fluoro containing waxes, olephinic waxes, silicone fluids, lubricants and silicone based waxes. Waxes may be blended in the composition in order to further increase the antisqueak lifetime of the composition, as described above. Preferably one or more waxes are included in the composition in an amount of less than 1 wt%, preferably from 0.01 to 1 wt%, more preferably from 0.1 to 0.5 wt% of the composition.

A copolyester with a relatively high amount of segment D can be employed in combination with a further copolyester not containing segment D, thus in a composition being a blend of at least two copolyesters. This has the advantage that the composition then may comprise segment D in a low amount with respect to the total mass of composition, while being dosed easily upon preparing the composition. For example, the composition may be a blend comprising: a copolyester as defined herein, wherein segment D is present in an amount of from 30 to 60 wt%; and a copolyester that comprises from 0 to 0 wt% of segment D.

Preferably, the composition does not include further copolyesters that do not contain segment D; thus preferably the copolyester in the composition consists of one or more copolyesters according to the present invention. The composition may not comprise a blend of copolyesters. The copolyester in the composition may consist of a single polyester according to the present invention. Such compositions are particularly effective at reducing squeak.

The copolyester, composition and/or article according to the present invention may be coated with a wax. This has the advantage of further preventing squeak. Suitable waxes include for example: microwaxes, fluoro containing waxes, olephinic waxes and silicone based waxes. Coatings may be achieved by spraying.

Article

The present invention provides an article comprising the copolyester or the composition as defined herein. Articles made from these copolyesters or compositions have been found to exhibit good reduction in squeak. In particular CVJ boots made from these copolyesters or compositions have been found to exhibit good noise reduction. Preferably, the article is for use in applications where the article will rub against another surface, which may result in undesirable squeak. By forming the article from the copolyester according to the present invention, the lifetime before squeak occurs is extended. In addition, once squeak occurs, the article may be dried in order to further prevent squeak. This is an advantage over articles formed from copolyesters or composition not according to the present invention.

The article may be for use in automotive applications, for example a CVJ boot, mattresses made from a 3D structure of fused monofilaments, or a shoe (mid-)sole.

The article may be entirely made from the copolyester or composition according to the present invention, or one or more surfaces of the article may be made from the copolyester or composition according to the present invention. For example, the article may be at least partially coated in the copolyester or composition according to the present invention. Preferably, at least one of the surfaces that rub against one another in use are made from or coated by the copolyester or composition according to the present invention. More preferably, all of the surfaces that rub against one another are made from or coated by the copolyester or composition according to the present invention.

Surfaces that rub against one another in use, and thus result in squeak, may be part of the same or different articles. In CJV boots, the surfaces may all be part of the same article. Thus, preferably, the CJV boot is formed from or coated by the copolyester or composition according to the present invention.

Also provided are granules comprising the copolyester and/or composition as described above. Surprisingly, the granules of the invention exhibit less sticking and thus may be more easily dosed and transported through various conventional transport equipment for further processing and/or storage. Preferably, the granules have a diameter of between 1 and 6 mm, more preferably between 2 and 5 mm, as these diameters allow easy processing of the granules.

Further provided is a film comprising the copolyester and/or composition according to the invention. Surprisingly, these films exhibit less adhesion to external surfaces upon preparing the film. With external surfaces is for example meant guidance rolls, chill rolls, high gloss chill rolls, nip rolls etc. The film may be a mono-layer or a multi-layer and less adhesion is observed if the layer in contact with the external surface, thus an outside layer, comprises or even consists of a copolyester according to the invention. The film may be prepared by processes known per-se, such as for example blown film process or cast process. Surprisingly, if employed in multilayer films, the inventors observed decreased adhesion to external surfaces, while adhesion with other layers of the film remained sufficient.

Article may be a molded article. This may be formed by any suitable process. The article may for example be blow molded or injection molded.

A molded article may be formed by a process comprising at least the following steps: a. Providing at least one copolyester as disclosed above; b. Heating the at least one copolyester to a temperature of at least 20 °C preferably at least 30 °C above Tm of the copolyester to obtain a melt; c. Introducing the melt into a mold; d. Solidifying the melt in the mold thereby obtaining the article.

In case the molded article is prepared by employing a composition comprising at least one copolyester, then the composition is preferably heated in step b. If the composition comprises polymers with varying melting temperatures, the composition is preferably heated to at least 30 °C above the highest melting temperature of the polymers or at least 15 °C above the end melting temperature (measured according to ISO 11357) to obtain a melt.

With the term melting temperature (Tm), as used herein, unless expressed otherwise, is herein understood the peak temperature of the endothermic melting peak measured by DSC of the copolyester or composition by the method according to ISO 11357-1/3 (2009) with a scan rate of 10° C/min in the second heating cycle. The standard protocol takes into account a sample mass of 3 to 8 mg in weight and apply the following temperature program: isothermal for 5 minutes at -100 °C, heating from -100 to 250 °C with 10 °C/min, holding isothermally for 1 min at 250 °C, followed by linear cooling from 250 °C to -100 °C with a cooling rate of -10°C/min, holding isothermal for 5 minutes at - 100 °C, followed by subsequent heating from -100 to 250 °C with 10 °C/min; the second heating cycle. The process as such is known in the art and may be referred to as blow-molding, compression molding or injection molding and can generally be described as providing a melt of the at least one copolyester or a composition which is subsequently introduced in a mold, after which the melt is solidified to obtain an article. Heating may be performed in an extruder or a hot press. Introduction of the melt into a mold may be done by injecting the melt into a mold in case of injection molding. The melt may also be introduced by extruding a parison which is subsequently introduced in a mold, after which pressure is applied to allow the parison to get in contact with the mold, after which the melt is solidified; this process is known as blow molding. Another process may also be compression molding, where granulates are placed into an open, mold cavity. The mold is closed with a metal lid, after which pressure and heat is applied to melt the granulates until a homogeneous melt is obtained in the shape of the molded article. The mold and lid are subsequently cooled down until the melt solidifies.

The method also includes overmolding, which is also a process known per se, in which another material is present in a mold in step c, to which the melt obtained from step b. is introduced. The another material can be chosen from a broad spectrum of materials, including for example polycarbonate, ABS, polyesters, such as PBT or PET, polyamides, as well as blends and copolymers. Surprisingly, sufficient adhesion may be obtained by overmolding, as compared to a composition in which polydimethylsiloxane is present instead of a copolyester comprising segment D.

The overmolding process is preferably so-called hard/soft overmolding and may be two-shot molding in one machine or separate molding in at least two machines. Double shot molding, also referred to as two-shot molding, is a manufacturing process used to produce complicated molded parts from at least two different compositions by molding a thermoplastic composition around a preformed metal or plastic insert. The process is relatively simple; one material is injected into a mold in order to make the initial piece of the product, followed by a second injection of another material that is compatible with the initial injection molded piece. The two plastic resins then form a molecular bond and the multi-resin molded part is cooled and ejected. One of the materials may be the copolyester containing segments S, D and H as disclosed herein.

At least a part of the article may be coated with a wax. Preferably the surface of the article that is in contact with another surface and may cause squeak is coated with a wax. The entire article may be coated in a wax. Suitable waxes include: microwaxes, fluoro containing waxes, olephinic waxes and silicone based waxes. This has the advantage of further preventing squeak.

Anti-Squeak

Squeak occurs when two surfaces rub against one another, resulting in noise. There is provided a method for preventing squeak comprising forming a surface from a copolyester or composition as disclosed herein.

Provided is a method for preventing squeak in an article comprising forming at least part of the article from the copolyester or composition as defined herein. Preferably, at least part of the surface of the article is formed from the copolyester or composition as defined herein. More preferably, the surface of the article is formed from the copolyester or composition as defined herein. Most preferably, the article is formed from the copolyester or composition as defined herein. Preferably the article is a CVJ boot.

In particular, the present invention provides a method of reducing or preventing squeak which is caused by two or more surfaces moving against one another by forming at least one of the surfaces from the copolyester or composition as defined herein. Preferably the two or more surfaces that rub against each other are formed from the copolyester or composition as defined herein. A least one of the surfaces, preferably the two or more surfaces, may be surfaces of the article as defined herein.

Squeak is particularly observed when two or more surfaces move against one another in the presence of water, therefore preferably squeak is reduced or prevented when two or more surfaces move against one another in the presence of water.

Without being bound by theory, it is believed that squeak may result from water on a surface, and may be the reason why squeak is often observed under wet conditions, where water is more likely to be present on the surface. Water may be in the form of liquid water or water vapour. Therefore, squeak may be observed more often in humid or wet, e.g. rainy, conditions. Therefore, squeak may be reduced by increasing the hydrophobicity of a surface. Without being bound by theory, it is believed that this is because this prevents retention of water on a surface. Hydrophobicity of a surface may be measured by the contact angle. Preferably, the static contact angle of the surface is at least 80 °, more preferably at least 85 °, even more preferably at least 90 °, most preferably at least 95 °. Preferably, the static contact angle of the surface is from 80 ⁰ to 120 °, more preferably from 85 ⁰ to 115 °, even more from preferably 90 °to 110 °, most preferably from 95 ⁰ to 105 °.

Static water contact angle may be measured as described in the experimental section below. An increased water contact angle also provides the advantage of improving the surface properties of the copolyester or composition by increasing stain resistance.

It has been found that removing the water from the copolyester surface, for example by drying, prevents squeak, or removes squeak when it has already been observed. Therefore, the method of reducing or preventing squeak disclosed herein may further comprise drying the copolyester or composition as defined herein. Drying may be performed in many ways and is not particularly limited. For example, drying may be performed by leaving the copolyester in the absence of liquid water for a period of time, such as 6 hours, 12 hours, 24 hours, 48 hours, 7 days or longer. Water vapour need not be removed, but dry air may be used. Alternatively, drying may be performed in an oven at 20 to 150 °C, for from 30 minutes to 7 days. Preferably, drying may be performed in an oven at 30 to 120 °C for from 2 hours to 2 days. More preferably, drying may be performed in an oven at 50 to 100 °C for from 4 hours to 1 day. Oven drying may be performed under a nitrogen atmosphere or under vacuum, which may speed up the process.

Also provided is the use of a copolyester or composition as disclosed herein for preventing squeak. Preferably, the copolyester or composition as disclosed herein prevents squeak when two or more surfaces move against one another. Examples

Materials and Methods

DSC

The melting temperatures were routinely determined using differential scanning calorimetry (DSC) by the method according to ISO 11357-1/3 (2009). The instrument was calibrated using an indium standard. Samples of 5-8 mg mass were weighed with a precision balance and encapsulated in (crimped) aluminum pans of known mass. Crucible’s covers were pre-pierced (50 micrometers hole) for allowing the atmosphere in the pan being refreshed during the experiment. An identical empty pan was used as a reference. Nitrogen is purged at a rate of 50 ml min"¹. Heating-Cooling-Heating cycles at 10K/min, in the range -8O...25O°C, were applied for determining the parameters that numerically characterize the thermal behavior of the investigated materials. The melting temperature is taken as the maximum height in the endotherm from the associated thermogram.

Shore D hardness and Shore A hardness

Shore hardness was measured according to international standard ISO 868-2003 with respect to specimen preparation. The instrument employed was a Zwick type 7206. For Shore A hardness, 0.5 - 8 N indenter pressure is employed. For Shore D hardness, 0 - 44 N indenter pressure is employed.

RSV

The relative solution viscosity (RSV) is measured according to ISO1628-5 at a concentration of 1 gram of polymer in 100 gram of m-cresol at 25 + 0.05 °C. Viscometer of the suspended level Ubbelohde type e.g. Cannon miniPV-HX was used.

Squeak test set-up

Squeak measurements were performed using a modified Taber abrasion test set-up. In this set-up, two wheels (made of the investigated material) are in contact with a plaque (of the investigated material), which is rotated by a rotating platform. A microphone records the sound (squeak) originating from wheel-plaque interaction in the presence of water. Apparatus: Taber abrasion tester Model 5135; Two wheels 050 mm, thickness = 10 mm and a plaque, 0110 mm, thickness = 2 mm. The wheels are mounted on an arm being part of the Taber abrasion tester. The total mass of each arm (including additional weights) equals 1000 gram. The wheels and plaque consist of the investigated material and are produced by injection molding or compression molding. The plaque is located on the rotating platform and rotates against the two small discs.

The plaque rotates at a speed of 60rpm, corresponding to a velocity of 14m/min. A Watson Marlow 120 U peristaltic Pump is used to dose every 15 seconds, one droplet of Milli-Q water so that a constant layer of water is present at the plaque.

Each test lasts 50.000 (fifty thousand) rotations (approximately 14 hours) after which the rotation stops and the surface is kept wet (hence, peristaltic pump is not stopped). In case the experiments continues (e.g. when no squeak was observed), a next test is manually started, typically after a waiting period of 10 hours.

Sound pressure (measured in dB) is collected by positioning a microphone (Velleman DVM173SD) at a distance of 4cm from the rotating plaque. Sound is recorded in a software program called Sound Datalogger version 2.0 at a sampling rate of 1 Hz. Squeak is considered to have occurred when sound reaches 75 dBa.

Water Contact Angel measurements (WCA)

Water contact angle (WCA) was measured from the static water contact angle. Samples were conditioned in standard lab conditions (23C / 50% RH) for at least one day before measurement of contact angles. Contact angles were measured using a KSV CAM 200 Video Contact Angle system. Calibration was performed directly in advance of the measurement series. A 3 pL drop of Milli-Q water was produced on a 0.5 (OD) needle and then by gently (automated) lowering of the syringe to the substrate and positioning the drop on its surface. The drop shape was monitored for 35 seconds with video at an image sample rate 2.5 fps. The movie was triggered by the lowering of the drop. From the obtained movie, the static contact angle was taken by drop-shape analysis of the images (using the Young-LaPlace equation to fit the drop shape) and as the static contact angle was taken the average of the values between 28 and 32 seconds. This was performed for the left as well as the right side of the drop and these values were averaged. Three or five different drops were measured, and the average is calculated.

¹H NMR spectroscopy

¹H NMR spectra were recorded on a Broker instrument operating at 500 MHz. Copolyester samples are dissolved in deuterated tetrachloroethane (TCE-d2). Composition is determined by integration of the signals attributed to the various segments. Molar mass of precursors were determined by comparison of integration of signals attributed to end-groups and repeating units for polymeric precursors.

Taber abrasion

Taber abrasion was measured with a taber abraser according to standard DIN 53754. The value is in mg of material collected after abrasion according to the standard.

Mar scratch resistance

Mar scratch resistance GME 60280 is measured in terms of delta gloss value. The measurements were performed on a Erichsen scratch tester with a coin shape marring element. Change of gloss grade at 60° was evaluated after plane flattening with 7 N force, 2 x 80 mar lines of 0.5 mm, at 1000 mm/min.

Mechanical properties

Mechanical properties like elongation at break, tensile strength and tensile modulus were obtained after injection molding 1 BA tensile bars, and performing testing according to ISO 527-11-2.

SEC measurements

Size exclusion chromatography was performed by the method as stated above.

Polymers according to the present invention and comparative polymers were prepared using the following methods.

Comparative polymers 1 , 3 and 4

A mixture of components listed in Table 1 were placed in a reactor. The mixture was placed under a nitrogen atmosphere and heated at atmospheric pressure to 220 °C while stirring. Once at 220 °C, vacuum was applied until the pressure inside the flask reached 300 mbar. The onset of condensation was monitored by distillation and collection of the first condensate, methanol, which indicates esterification and oligomer formation. The reaction mixture was then heated further to 246 °C under vacuum until the pressure in the flask was approximately 1 mbar. The torque associated with the gradual viscosity buildup was monitored, and the reaction was stopped at a target melt viscosity. The melt was extruded and cooled in a waterbath, and finally the resulting strand was granulated. Results are provided in Tables 2 and 3.

Comparative composition 2

Preparation of a composition containing a blend of comparative polymer 1 and Polydimethylsiloxane (PDMS). PDMS having methyl end-groups and a number average molecular weight of approximately 14 000 g/mol was added to the reactor at the beginning of the reaction described in comparative polymer 1 above. The other components were added in the same proportions as described in comparative polymer 1 . Results are provided in Tables 2 and 3.

Polymers 5-7 and 9-11 and Comparative Polymer 8

A mixture of components listed in Table 1 were placed in a stainless steel reactor. The mixture was gradually heated at atmospheric pressure to 220 °C while stirring. Once at 220 °C, vacuum was applied until the pressure inside the flask reached 300 mbar. The onset of condensation was monitored by distillation and collection of the first condensate, methanol, which indicates esterification and oligomer formation. The reaction mixture was then heated further to 246 °C while simultaneously reducing the pressure from atmospheric pressure to approximately 1 mbar. The torque associated with the gradual viscosity buildup was monitored, and the reaction was stopped at a target melt viscosity. The number average molecular weight of the sample was determined and the dispersity (M_w/M_n) as determined by SEC. The melt was extruded and cooled on a water-cooled belt, and finally the resulting strand was granulated. Results are provided in Tables 2 and 3.

Polymers 13 to 16 and Comparative Polymer 12

A mixture of components listed in Table 1 were placed in a reactor. The mixture was placed under a nitrogen atmosphere and heated at atmospheric pressure to 220 °C while stirring. Once at 220 °C, vacuum was applied until the pressure inside the flask reached 300 mbar. The onset of condensation was monitored by distillation and collection of the first condensate, methanol, which indicates esterification and oligomer formation. The reaction mixture was then heated further to 242 °C under vacuum until the pressure in the flask was approximately 1 mbar. The torque associated with the gradual viscosity buildup was monitored, and the reaction was stopped at a target melt viscosity. The melt was extruded and cooled in a waterbath, and finally the resulting strand was granulated. Results are provided in Tables 2 and 3.

Table 1 : Components used in the synthesis of Polymers or Comparative Polymers.

Table 2: Summary of polymers

Table 2 continued:

f segment D

Table 2 continued:

Number average values (e.g. Mn, x, y, z, v, w, m and p) determined by ¹H-NMR, unless stated otherwise.

Granules were produced from Comparative Polymers 1 , 2, and 3. These were found to stick together in large agglomerates. Sticking was also observed for Comparative polymer 9. In contrast, the granules produced from Polymer 5 do not stick together at all. The mechanical properties of the materials produced in Comparative polymer 1 and Example 5 are nearly identical. Also for Examples 6 and 7, as well as Examples 9, 10 and 11 no sticking was observed.

Molded articles were also prepared from Comparative polymers 1 and 4 and Polymers 7 and 9 to 11 . Water contact angles were measured as this provides a measure for the surface quality. Results are provided in Table 4. Molded articles according to the invention, exhibit higher contact angles as compared to molded articles not according to the invention. Thus, the polymers according to the present invention demonstrate improves surface properties. This also suggests that polymers according to the present invention will prevent squeak for longer than polymers not according to the present invention.

Table 4 Results Molded parts

Compositions

From polymer 9 and comparative polymer 4 compositions were made. This was done by extruding the ingredients as listed in Table 5, followed by granulation. The obtained granules were subjected to a method comprising the following steps which resulted in a molded article: a. Providing granules with a composition as listed in Table 5 to an extruder; b. Heating the composition to a temperature to obtain a melt; c. Introducing the melt into a mold; d. Solidifying the melt in the mold thereby obtaining the article. Silicone additive 1 : Pelletized silicone gum formulation with approximately 70 % ultrahigh molecular weight siloxane polymer and 30% fumed silica.

Silicone additive 2: Silicone containing masterbatch containing approximately 50 % ultra high molecular weight polysiloxane in a polyethylene carrier.

Color additive: 50% carbon black color masterbatch in copolyester carrier

Table 5 Compositions

Results are provided in Table 6. Table 6; results of molded articles

Examples 1 , 2 and 3 show improvement in stress mark appearance versus

Comparative experiments A, B, C and D. Examples 1 to 4 show that compositions with polymer 9 are able to deliver a modified surface with a higher water contact angle than compositions containing comparative polymer 4. Comparative experiments B and C show that trying to modify the surface by using silicone containing additives that are not covalently part of the chain, thus as a blend, is less effective than by using polymers that contain segment D. Additionally, examples 2 and 3 as compared to comparative experiment B and C show that using a non-covalently bonded silicone in a blend, may lead to sticking related problems during molding. Example 1 shows that a molded article according to the invention may deliver modified surface with no sticking. Lastly, comparative experiment D has a shore hardness of 80A which is similar to Example 1 but does not show the improved surface and has worse stress mark appearances.

Plaques and disk-shape wheels were formed by compression molding of the compositions on a Colin lab line P 400 SV, operated under nitrogen atmosphere. Granulates were placed in a mold at room temperature. The mold was closed and clamped in the compression molding machine, using no pressure, during 1800 seconds at 235°C (pre-heating). After pre-heating, two pressing steps are applied. In the first pressing step, the 2mm thick plaques were pressed for 600 seconds at 4bar at 235°C and the 10mm thick plaques were pressed for 1800 seconds at 4bar at 235°C. In the second pressing step, both plaques were pressed during 600 seconds at 10bar at 235°C. Subsequently, the mold was cooled down during 1000 seconds from 235°C to 25°C at a pressure of 10 bar. After molding, the plaques were removed from the mold. The 10mm thick plaques were milled using a milling machine to the dimensions as described before (01 10 mm).

Compositions with higher molecular weights by solid state post condensation were prepared.

Comparative composition C17, composition 18 and 19:

Comparative composition 17:

Comparative polymer 12 was submitted to solid state postcondensation while simultaneously absorbing Naugard 445 stabilizer on the polymer pellets. The solid polymer pellets together with Naugard 445 were loaded in a tumble dryer and heated to perform solid state post condensation under vacuum atmosphere until the target RSV was reached. The granulates were dry-blended with carbon black masterbatch at room temperature. Amounts are given Table 6A. The final polymer in comparative composition 17 had an Mn of 45500 and an RSV of 4.50. Composition 18:

Polymer 13 was submitted to solid state postcondensation while simultaneously absorbing Naugard 445 stabilizer on the polymer pellets. The solid polymer pellets together with Naugard 445 were loaded in a tumble dryer and heated to perform solid state post condensation under vacuum atmosphere until the target RSV was reached. The granulates were dry-blended with carbon black masterbatch at room temperature. Amounts are given Table 6A. The final polymer in composition 18 had an Mn of 23700 and an RSV of 4.43.

Composition 19

Polymer 14 was submitted to solid state postcondensation while simultaneously absorbing Naugard 445 stabilizer on the polymer pellets. The solid polymer pellets together with Naugard 445 were loaded in a tumble dryer and heated to perform solid state post condensation under vacuum atmosphere until the target RSV was reached. The granulates were dry-blended with carbon black masterbatch at room temperature. Amounts are given Table 6A. The final polymer in composition 19 had an Mn of 19800 and an RSV of 4.14.

Table 6A amounts in compositions:

*Carbon masterbatch consisted of 20 wt% carbon black with 80 wt% thermoplastic copolyester carrier Injection molding to prepare plaques for squeak testing of Comparative composition

C17 and Compositions 18 and 19

Plaques and disk-shape wheels were formed by injection molding of the compositions. The 10mm thick plaques were milled using a milling machine to the dimensions as described before (0110 mm).

Squeak tests

Squeak was measured as described above. Squeak was considered to have occurred when sound reaches 75 dBa.

Table 7: Squeak test

%D is with respect to the weight of the polymer.

** No squeak was detected up to 1100000 cycles and test stopped, n.d. is not determined

This data shows that squeak was observed from a very early time point when no D segment is included, such as within 50000 cycles. In polymers including segment D of at least 5%, the amount of time before squeak occurs was significantly increased. This data shows that the amount of segment D directly correlates to the degree of reduction of squeak. For compositions 18 and 19 furthermore an improvement of squeak behavior was observed as compared to the non-solid state post condensed polymers 13 and 14.

Squeak tests with drying

Polymer 14 underwent several cycles of drying/squeak testing to evaluate whether drying can be used to prevent or reduce squeak for a longer period of time. These results are shown in Table 8. Squeak was measured as described above. Squeak was considered to have occurred when sound reaches 75 dBa.

During Run 1 , squeak started after 67 hours. After Run 1 , both wheels and the plaque were dried for 48 hours at 23 °C, 50%RH, after which the squeak test was started again (Run 2). During Run 2, it took 20 hours for the squeak to re-occur. After Run 2, both wheels and the plaque were dried in an oven for 48 hours at 23 °C, under vacuum, after which the squeak test was started again (Run 3). During Run 3, it took 25 hours for the squeak to re-occur. After Run 3, both wheels and the plaque were dried in an oven for 7 days at 23 °C, under Nitrogen, after which the squeak test was started again (Run 4). During Run 4, it took 140 hours for the squeak to re-occur.

The above observation surprisingly show that not only is squeak prevented initially (i.e. during Run 1 prior to drying), but also that squeak can be prevented once it is observed by drying the composition under several conditions (e.g. as shown in Runs 2 to 4).

Table 8: Polymer 14 squeak testing with drying

Claims

CLAIMS Copolyester comprising hard segment H comprising at least one monomeric unit of Formula (1 ), soft segment S comprising at least one monomeric unit of Formula (2), and segment D comprising at least one monomeric unit of Formula (3), with

wherein the number average value of p is from 4 to 100;

R¹ and R² are substituents independently chosen from alkyl, aralkyl and aryl;

R⁵ is a polymer chosen from polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of polyethylene oxide and polypropylene oxide, linear aliphatic polycarbonates, polybutylene adipate (PBA) and derivates of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters and combinations thereof; wherein the amount of segment D is between 0.1 and 60 wt% and the total amount of segments H, S and D is at least 90 wt% wherein wt% is with respect to the total mass of copolyester, and wherein the number average molecular weight of the copolyester is at least 10 000 g/mol. Copolyester according to claim 1 , wherein segment H consists of monomeric units of Formula (1 ), and soft segment S consists of monomeric units of Formula (2), and segment D consists of monomeric unit of Formula (3). Copolyester according to claim 1 or 2, wherein

R¹ and R² are substituents independently chosen from methyl, ethyl, propyl, benzyl and aryl;

R³ and R⁴ are substituents independently chosen from methylene, ethylene, propylene, benzylene, or combinations thereof. Copolyester according to any one of the above claims, wherein: a) R¹ and R² are the same substituent, preferably wherein R¹ and R² are methyl; and/or b) R³ and R⁴ are the same substituent, preferably wherein R³ and R⁴ are propylene. Copolyester according to any one of the above claims, wherein b¹+b²=B and the number average molecular weight ratio of A:B is from 3:1 to 1 :3. Copolyester according to any one of the above claims, wherein the number average molecular weight of segment D is from 1000 to 6000 g/mol, preferably from 1250 to 4000 g/mol, most preferably 1500 to 3500 g/mol. Copolyester according to any one of the above claims, wherein the amount of segment D is between 0.5 and 50 wt%, preferably between 5 and 40 wt%, even more preferably between 10 and 30 wt%, most preferably between 15 and 25 wt%, wherein wt% is with respect to the total mass of copolyester. Copolyester according to any one of the above claims, wherein t=2. Copolyester according to any one of the above claims, wherein the hard segments H are chosen from PBT and PET and combinations thereof. Copolyester according to any of the above claims, wherein R⁵ is polytetramethylene oxide (PTMO). Copolyester according to any one of the above claims, wherein: a) the amount of soft segment S is between 20 and 80 wt%, wherein wt% is with respect to the total mass of copolyester; and/or b) the amount of hard segment H is between 15 and 90 wt%, wherein wt% is with respect to the total mass of copolyester. Composition comprising the copolyester according to any one of the claims 1 to 11. Composition according to claim 12, further comprising: a) one or more additives; b) one or more additional polymers; and/or c) one or more waxes. Article comprising the copolyester according to any one of the claims 1 to 11 or the composition according to claims 12 or 13. Method of reducing or preventing squeak, comprising forming a surface from the copolyester according to any one of the claims 1 to 11 or the composition according to claims 12 or 13.