Conveyor belt

Abstract

The present invention provides a polyester-based hard segment having a melting temperature T of 200°C to 240°C, measured according to ISO 11357-1 / -3 (10°C / min). mA a) a (co)polyester A having a melting temperature T of 100°C to 180°C, measured in accordance with ISO 11357-1 / -3 (10°C / min), of 100°C to 180°C, wherein the (co)polyester A is present in an amount of 1 to 60% by weight, based on the total weight of the composition; and b) a copolyester B comprising a hard segment comprising a polyester, wherein the (co)polyester B has a melting temperature T of 100°C to 180°C, measured in accordance with ISO 11357-1 / -3 (10°C / min). mB and copolyester B is present in an amount of 40 to 99% by weight, based on the total weight of the composition. The present invention also relates to a process for preparing a conveyor belt.

Description

Detailed Description of the Invention

[0001] The present invention relates to conveyor belts. Conveyor belts are well known and are described, for example, in U.S. Patent Application Publication No. 2005082147A. Conveyor belts, particularly extruded conveyor belts, must remain flat throughout their lifespan and therefore exhibit low camber to function properly. Furthermore, flights, teeth, and / or guides are commonly welded to conveyor belts to enable more efficient transport of goods or to support belt movement. Furthermore, conveyor belts must operate over a wide temperature range (e.g., from −30° C. to +120° C.) while still maintaining sufficient rigidity. In addition, conveyor belts are typically spliced ​​together into one piece. Conveyor belts must be cleaned periodically and therefore must exhibit sufficient chemical resistance.

[0002] Therefore, conveyor belts must satisfy various requirements. An object of the present invention is to provide a conveyor belt that has sufficient welding performance, little warping, and sufficient rigidity to bear a required load.

[0003] The purpose of this is to a) A hard segment containing polyester, with a melting temperature T of 200°C to 240°C measured according to ISO 11357-1 / -3 (10°C / min) mA wherein the (co)polyester A is present in an amount of 1 to 60% by weight based on the total weight of the composition; b) a copolyester B comprising a hard segment comprising a polyester, wherein (co)polyester B has a melting temperature T of 100°C to 180°C, measured according to ISO 11357-1 / -3 (10°C / min). mB and Copolyester B is present in an amount of 40 to 99 wt % based on the total weight of the composition.

[0004] Surprisingly, the inventors have found that conveyor belts according to the present invention exhibit good welding performance while maintaining sufficient chemical resistance and stiffness, as demonstrated by the examples. In addition, the conveyor belts exhibited much higher tensile strength and load-bearing capacity than conventional copolyester belts of similar stiffness.

[0005] Preferably, the conveyor belt has a closed surface, which is particularly beneficial when transporting food products, as this may reduce contamination. By "closed surface" is herein understood a surface without holes.

[0006] Many plastics are listed as suitable materials for conveyor belts. For example, U.S. Patent Application Publication No. 2005082147A lists thermoplastic materials such as polyester or COPE for extruded conveyor belts, but many of these materials exhibit warping. Many materials used as conveyor belt materials warp after extrusion or during the belt's lifespan. "Warping" in this specification refers to the process in which differences in polymer molecular flow and crystallization patterns cause the frozen tension in the extruded material to relax, resulting in anisotropic dimensional changes in the extruded material, including the belt, resulting in "warping" of the belt. This process can already begin when the belt is cut to the desired width and length and may even become more pronounced as a function of time, at high temperatures, and / or under the influence of (cleaning) chemicals during belt use.

[0007] Another advantage of the conveyor belt according to the invention is that it can be operated over a wide temperature range, for example, from -30 to 120°C. This also makes it possible to clean the conveyor belt with chemicals at high temperatures without damaging the conveyor belt. Surprisingly, the conveyor belt according to the invention can also be operated under humid conditions.

[0008] Conveyor belts are regularly cleaned using various cleaning agents, which may be antibacterial agents, strong acids, peroxides, disinfectants, etc. Surprisingly, the conveyor belt according to the present invention exhibits sufficient chemical resistance.

[0009] As used herein, (co)polyester refers to a class of polymers that includes both polyester homopolymers and copolyesters.

[0010] Copolyesters having specific melting temperatures are known in the art. The melting temperature of a copolyester can be affected, for example, by the amount of hard and soft segments in the copolyester, as well as the chemical nature of the hard and soft segments, including their length and type.

[0011] [(Co) Polyester A] The conveyor belt contains polyester hard segments and has a melting temperature T of 200°C to 240°C, measured according to ISO 11357-1 / -3 (10°C / min). mA wherein (co)polyester A is present in an amount of 1 to 60 wt %, based on the total weight of the composition.

[0012] The conveyor belt contains polyester hard segments and has a melting temperature T of 200°C to 240°C. mA The present invention also includes compositions comprising "(co)polyester A" which comprises two or more types of (co)polyester A having the following formula:

[0013] The hard segments of the polyester can be, for example, polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polybutylene isophthalate (PBI), polyethylene isophthalate (PEI), polyethylene naphthalate, polybutylene naphthalate, and polypropylene naphthalate, as well as combinations thereof. Preferably, the hard segments of (co)polyester A are PBT because PBT is readily available. (Co)polyester A can consist of a PBT hard segment, in which case it is also called PBT and is therefore a polyester homopolymer. (Co)polyester A can also contain two or more hard segments, such as PBT and PBI, in which case it is a copolyester.

[0014] The (co)polyester A may also contain soft segments, which can be selected from a wide range of polymers, including, for example, polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of poly(ethylene oxide) and poly(propylene oxide), linear aliphatic polycarbonates, polybutylene adipate (PBA), and derivatives of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters, and combinations thereof. Preferably, the (co)polyester A contains soft segments comprising polytetramethylene oxide (PTMO). The preferred amounts of hard segments and optional soft segments in the (co)polyester A may vary and depend on the type of segments and the desired stiffness for the application. Table 1 below shows a selection of various (co)polyesters A according to the present invention, each having different melting temperatures (Tm), which can be achieved by using, for example, only PBI or PTMO of varying lengths, or PBT, in the chemical structure of the (co)polyester A. For the avoidance of doubt, (co)polyester A includes a wide range of (co)polyesters and is not limited to those set out in Table 1.

[0015] [Table 1]

[0016] (J) Melting temperature T of polyester A mA is 200°C to 240°C measured according to ISO 11357-1 / -3 (10°C / min). mA More preferably, (co)polyester A is PBT and has a T of about 225°C. mA which is readily available.

[0017] The relative solution viscosity of the (co)polyester A is a property known per se and can be influenced by the polymerization conditions. The relative solution viscosity can be further increased, for example, by a solid-state post-condensation process also known per se.

[0018] The viscosity number (VN) calculated according to ISO1628-5:1998 can be expressed in terms of relative solution viscosity by the following formula: VN=(η r -1)×1 / c (Equation 1).

[0019] In this case, η r is the relative solution viscosity (RSV) and c is the polymer concentration (0.005 g / ml) as specified by the ISO standard.

[0020] Preferably, the extruded conveyor belt comprises a (co)polyester A, wherein the (co)polyester A exhibits an RSV of at least 1.55, more preferably at least 1.85, and even more preferably at least 2.10, measured according to ISO 1628-5:1998 using m-cresol as solvent at 25° C. The RSV of the (co)polyester A can also be as high as, for example, 4.0.

[0021] The amount of (co)polyester A present in the composition of the conveyor belt according to the present invention is important for the final mechanical strength, such as tensile strength, abrasion resistance and abrasion resistance, as well as chemical and heat resistance, of the belt, and is therefore 1 to 60% by weight, preferably 5 to 50% by weight, and even more preferably 8 to 40% by weight, based on the total weight of the composition. When multiple (co)polyesters A are present, the above amount refers to the total amount of all (co)polyesters A.

[0022] [Copolyester B] The conveyor belt has a polyester hard segment and a melting temperature T of 100°C to 180°C, measured according to ISO 11357-1 / -3 (10°C / min). mB The conveyor belt includes a copolyester B having a polyester hard segment and a melting temperature T mA The copolymer may comprise two or more copolyesters B having the formula:

[0023] The hard segment of the polyester may be, for example, polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), polybutylene isophthalate (PBI), polyethylene isophthalate (PEI), polyethylene naphthalate, polybutylene naphthalate, and polypropylene naphthalate, and combinations thereof. Preferably, the hard segment of copolyester B is PBT, and more preferably, the hard segment is a combination of PBT and PBI, because this is readily available and can lower the melting temperature of (co)polyester B.

[0024] Copolyester B can also contain soft segments, which can be selected from a wide variety of polymers, including, for example, polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polypropylene oxide (PPO), block copolymers of poly(ethylene oxide) and poly(propylene oxide), linear aliphatic polycarbonates, polybutylene adipate (PBA), and derivatives of dimer fatty acids or dimer fatty acid diols, linear aliphatic polyesters, and combinations thereof. Preferably, copolyester B contains soft segments comprising polytetramethylene oxide (PTMO), which is FDA approved for food contact. The preferred amounts of hard segments and optional soft segments in copolyester B can vary and depend on the type of segments and the desired rigidity for the application. Table 2 below lists suitable examples of copolyesters B having melting temperatures between 100°C and 180°C. For the avoidance of doubt, copolyester B includes a wide variety of copolyesters and is not limited to those listed in Table 2.

[0025] The PBI hard segments may be present in an amount of 0 to 50% by weight, preferably 5 to 40% by weight, based on the total amount of copolyester B. The PTMO soft segments may be present in an amount of 0 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of copolyester B. The amount and type of hard and soft segments may be determined by infrared spectroscopy or nuclear magnetic resonance spectroscopy.

[0026] [Table 2]

[0027] Melting temperature T of copolyester B mB The heating temperature is 100°C to 180°C, preferably 140°C to 175°C.

[0028] The amount of copolyester B is 40 to 99 wt %, preferably 50 to 95 wt %, and even more preferably 60 to 93 wt %, based on the total weight of the composition. The conveyor belt comprises a composition comprising "copolyester B" that contains two or more types of copolyester B. When two or more copolyesters B are present, the above amount refers to the total amount of all copolyesters B.

[0029] Preferably, the copolyester B has a melting temperature T of at most 175°C, more preferably at most 170°C, measured according to ISO 11357-1 / -3 (10°C / min). mB This improves weldability with other components.

[0030] Preferably, the extruded conveyor belt comprises a copolyester B, wherein the copolyester B exhibits an RSV of at least 2.0, more preferably at least 2.2, and even more preferably at least 2.5, measured according to ISO 1628-5:1998 at 25° C. using m-cresol as the solvent. The RSV can be, for example, as high as 4.0.

[0031] The copolyesters can be prepared by methods known in the art, for example, as described in "Handbook of Thermoplastics," Marcel Dekker, Inc., 1997, pages 399-401.

[0032] The conveyor belt composition according to the invention preferably has a bimodal melting behavior showing at least two peaks, one peak P1 between 200°C and 240°C, and another peak P2 between 100°C and 180°C. By "bimodal melting behavior" it is understood herein that the melting curve of the conveyor belt composition according to the invention shows at least two peaks in a defined region, and expressly includes melting curves with three or more peaks. Preferably, P1-P2 is at least 40°C, more preferably at least 50°C, and most preferably at least 60°C.

[0033] Preferably, the conveyor belt composition according to the invention exhibits an elongation at break measured in a 1BA injection-molded tensile bar and tested according to ISO 527-1 / -2 of at least 50%, more preferably at least 100%, and even more preferably at least 150%, thereby enabling a flexible conveyor belt.

[0034] Preferably, the composition of the conveyor belt according to the present invention has a bimodal melting behavior exhibiting at least two peaks as disclosed above, in which case T mA and T mB The difference between T is at least 40°C, more preferably at least 50°C, and most preferably at least 60°C, which ensures limited or no transesterification between the (co)polyester A phase and the copolyester B phase, thereby providing the advantages of good RF weldability and limited warpage behavior after extrusion. mA and T mB If the difference between P1 and P2 is lower, this indicates that too much transesterification has occurred, which is detrimental to weldability.

[0035] The conveyor belt according to the present invention can be prepared by processes known in the art. Preferably, the conveyor belt is prepared by at least the following steps: a) Contains polyester hard segments and has a melting temperature T of 200°C to 240°C, measured according to ISO 11357-1 / -3 (10°C / min). mA a (co)polyester A having the formula: Contains polyester hard segments and has a melting temperature T of 100°C to 180°C, measured according to ISO 11357-1 / -3 (10°C / min). mB Copolyester B having providing a composition comprising: a copolyester B, wherein the copolyester B is present in an amount of 40 to 99 wt. %, based on the total weight of the composition; b) bringing the composition to a temperature of 230°C to 290°C to form a melt; c) extruding the melt through a die; d) cooling the extruded melt to form a conveyor belt; e) optionally welding the part to the conveyor belt.

[0036] This process, also referred to as an extrusion process, provides an extruded conveyor belt. Surprisingly, this process results in a conveyor belt that exhibits less warpage. Accordingly, the present invention also relates to an extruded conveyor belt comprising the composition as disclosed herein. After step d), the cooled extruded melt can be cut and sliced ​​to desired widths, lengths, and / or dimensions and can be spliced ​​to form an endless belt.

[0037] Preferably, T mA and T mB is at least 40°C, more preferably at least 50°C, and most preferably at least 60°C. A further advantage is that the conveyor belt can be prepared using higher extrusion throughput, thereby reducing the production time of the conveyor belt. In preparing the conveyor belt, further processing steps can be utilized, such as, for example, splicing the ends together to form a continuous belt. Surprisingly, by using compositions as disclosed above in conveyor belts, splicing can be advantageously utilized.

[0038] The welding can be performed by welding techniques known per se, such as, for example, high frequency welding (RF-welding), vibration welding, etc. Preferably, RF or high frequency (HF)-welding is performed, as this is the preferred technique used by the belt industry due to its excellent reliability, reproducibility (quality) and versatility. The further parts can be made of different materials, but are preferably made of the same composition as the belt.

[0039] The composition can be provided in step a) by providing the individual components separately, for example, by providing (co)polyester A and copolyester B in separate feeders. The composition can also be provided as a blend in step a), which can be obtained, for example, by dry blending or melt mixing (co)polyester A and copolyester B, which are processes known to those skilled in the art. The melt mixing can be carried out, for example, in an extruder, optionally followed by a granulation step. This facilitates further processing of the composition.

[0040] Preferably, the process is carried out with a (co)polyester A having a low moisture content, for example, a moisture content of at most 0.02% by weight, preferably at most 0.01% by weight, based on the total weight of (co)polyester A. Preferably, the process is carried out with a copolyester B having a low moisture content, for example, a moisture content of at most 0.02% by weight, preferably at most 0.01% by weight, based on the total weight of copolyester B. Even more preferably, both (co)polyester A and copolyester B exhibit a low moisture content as disclosed above. This has the advantage that the decrease in viscosity is limited. Preferably, (co)polyester A and / or copolyester B are subjected to a drying step to reduce the moisture content of (co)polyester A and / or copolyester B before bringing (co)polyester A and copolyester B to a temperature of 230°C to 290°C to form a melt. Drying can be carried out by known means.

[0041] The conveyor composition according to the present invention may further comprise components commonly known in the art, such as nucleating agents, colorants, flame retardants, polytetrafluoroethylene (PTFE), stabilizers, and reinforcing fillers such as glass fibers. Nucleating agents include, for example, sodium benzoate. For food applications, the conveyor belt preferably does not contain glass fibers. Preferably, the conveyor belt comprises a composition consisting essentially of (co)polyester A, copolyester B, and optionally a colorant; therefore, the amounts of (co)polyester A and copolyester B and any optional additives add up to 100% by weight of the total composition.

[0042] The present invention also relates to a process for transporting food products, comprising at least the following steps: a. providing food on a conveyor belt; b. moving the conveyor belt with the food product in a desired direction; In this case, the conveyor belt is a belt according to the invention as disclosed above. Surprisingly, this process allows for less degradation after cleaning compared to processes in which, for example, conveyor belts made of thermoplastic polyurethane (TPU) or polyether block amide, also known as Pebax®, are used. Another advantage is that the conveyor belt can be recycled at the end of its life.

[0043] [Conveyor belt] Conveyor belts according to the present invention can have a wide range of widths, for example, from as low as 20 cm to as wide as 3 m, generally depending on the intended use of the belt. Surprisingly, conveyor belts having higher widths, for example, at least 100 cm, still exhibit low camber.

[0044] The thickness of the conveyor belt can also vary, for example, from 1 mm to 10 mm, again depending on the intended use of the belt. Optional flights and sidewalls can be present, preferably comprising the same composition as the conveyor belt, which facilitates recycling of the belt after use.

[0045] Preferably, the conveyor belt according to the present invention is monolithic and therefore consists of the composition as disclosed above.

[0046] Preferably, the conveyor belt according to the invention is an extruded conveyor belt and is therefore prepared by extrusion.

[0047] The conveyor belt according to the invention can be used in various fields, such as for the transport of goods, in particular food products.

[0048] [Example] [Materials used] [Polyester AI, PBT] Melt volume-flow rate (T=250℃, weight=2.16kg): 22cm according to ISO1133 3 / 10 minutes Melting temperature (10°C / min): 225°C according to ISO11357-1 / -3 Water absorption rate: 0.45% by weight (ISO62) Moisture absorption rate: 0.18% by weight (ISO62) Density: 1300kg / m according to ISO1183 3 RSV (m-cresol, 1 g / 100 mL): 2.1 (ISO 1628-5: 1998 and ISO 307)

[0049] [(Co) Polyester A-II] Copolyetherester based on PBT as hard segment and PTMO as soft segment, containing 65 m / m% hard segment and 35 m / m% soft segment. Melt volume flow rate (T=230℃, weight=2.16kg): 9cm according to ISO1133 3 / 10 minutes Melting temperature (10°C / min): 207°C according to ISO11357-1 / -3 Water absorption rate: 0.65% by weight (ISO62) Moisture absorption rate: 0.20% by weight (ISO62) Density: 1200kg / m 3 (ISO1183) Shore D hardness (3s): 52 (ISO868) RSV (m-cresol, 1g / 100mL): 3.2 (ISO1628-5:1998 and ISO307)

[0050] [(Co) Polyester A-III] Copolyetherester based on PBT as hard segment and PTMO as soft segment, containing 75 m / m % hard segment and 25 m / m % soft segment. Melt volume flow rate (T=230℃, weight=2.16kg): 4cm according to ISO1133 3 / 10 minutes Melting temperature (10°C / min): 212°C according to ISO11357-1 / -3 Water absorption rate: 0.6% by weight (ISO62) Moisture absorption rate: 0.20% by weight (ISO62) Density: 1240 kg / m according to ISO 1183 3 Shore D hardness (3s): 60 (ISO868) RSV (m-cresol, 1g / 100mL): 3.4 (ISO1628-5:1998 and ISO307)

[0051] [(Co) Polyester A-IV] Copolyetherester based on PBT as hard segment and PTMO as soft segment, containing 90 m / m% hard segment and 10 m / m% soft segment. Melt volume flow rate (T=230℃, weight=2.16kg): 18cm according to ISO1133 3 / 10 minutes Melting temperature (10°C / min): 221°C according to ISO11357-1 / -3 Water absorption rate: 0.6% (ISO62) Moisture absorption rate: 0.15% (ISO62) Density: 1290 kg / m according to ISO11833 Shore D hardness (3s): 70 (ISO868) RSV (m-cresol, 1g / 100mL): 2.3 (ISO1628-5:1998 and ISO307)

[0052] [Copolyester BI] A copolyester based on both PBT and PBI as hard segments and PTMO as soft segments, containing 65 m / m% hard segments and 35 m / m% soft segments. Melt volume flow rate (T = 230°C, weight = 2.16 kg): 25 m according to ISO 1133 3 / 10 minutes Melting temperature (10°C / min): 165°C according to ISO11357-1 / -3 Water absorption rate: 0.65% by weight (ISO62) Moisture absorption rate: 0.20% by weight (ISO62) Density: 1190 kg / m according to ISO 1183 3 RSV (m-cresol, 1g / 100mL): 2.8 (ISO1628-5:1998 and ISO307)

[0053] [Preparation of Composition] The formulations listed in Table 3 were prepared by hand mixing the granules in the prescribed proportions before injection molding.

[0054] [Table 3]

[0055] Preparation of test plaques and 1BA tensile bars by injection molding Where applicable, the ISO 294-1 standard was used.

[0056] Plaques measuring 120 x 120 x 4.0 mm were molded from the pre-dried material. The material was dried at 120°C for 6 hours with vacuum and N2 purge. The moisture content after drying was at maximum moisture value (less than 500 ppm). The material was processed in an Arburg brand injection molding machine with a clamping force of 150 tons and a screw diameter of 40 mm. The measured melt temperatures were 247 and 248°C. The measured mold temperature was 40-43°C. The thickness of the produced plaques was measured to be 3.97-4.0 mm.

[0057] The parts are packaged dry in sealed pouches.

[0058] Plaques measuring 80 x 80 x 1 mm were molded from the pre-dried material. The material was dried at 120°C for 6 hours with vacuum and N2 purge. The moisture content after drying was at maximum moisture value (less than 500 ppm). The material was processed in an Arburg brand injection molding machine with a clamping force of 110 tons and a screw diameter of 25 mm. Melt temperatures were measured at 246 and 247°C. Mold temperatures were measured between 17 and 27°C. The thickness of the produced plaques was measured at 1.02 mm. The parts were packaged dry in sealed pouches.

[0059] Tensile bars ISO 527-1BA were molded from the pre-dried material. The material was dried at 120°C for 6 hours with vacuum and N2 purge. The moisture content after drying was at maximum moisture value (less than 500 ppm). The material was processed in an Arburg brand injection molding machine with a clamping force of 70 tons and a screw diameter of 20 mm. The measured melt temperature was 229-236°C. The measured mold temperature was 46-51°C. The thickness of the produced bars was measured to be 2.04-2.05 mm. The parts were packaged dry in sealed bags.

[0060] [Relative solution viscosity] Relative solution viscosity was determined in a solution of 1.0 g of material in 100 ml of m-cresol at 25°C according to ISO 1628-5:1998.

[0061] [Mechanical properties] Type 1BA tensile bars were tested in accordance with ISO 527 using a ZwickRoell Z010 tensile testing machine equipped with a 2.5 kN force cell, a Zwick Multisens contact extensometer with a 25 mm gauge length, and a Zwick pneumatic clamp with a 58 mm grip distance. After applying a 0.5 N preload, the test was initiated at a test speed of 1 mm / min to determine the E modulus (0.05%–0.25%), followed by testing at a test speed of 500 mm / min until failure. Strain was measured with the extensometer up to 60% strain and then by traverse displacement until failure. The tensile strength (MPa) was determined as the highest stress observed during the test. Tests were performed in five separate runs. The specimens were kept "dry as molded" during testing, and the test was conducted at a test temperature of 23°C. "Dry as molded" is understood herein to mean that the specimens are placed in a moisture-proof container immediately after molding and stored at (23±2)°C for at least 24 hours, with a moisture content of less than 0.2% (mass fraction).

[0062] [Dynamic mechanical analysis (DMA)] Torsion DMA (DMA in torsion), as generally described in ASTM D5279, was performed on injection-molded plaques measuring 150 mm x 150 mm x 4.0 mm. Measurement specimens were sawed to the appropriate length (10 mm x 55 mm) parallel and perpendicular to the melt flow direction during injection molding. Dimensions were measured using a calibrated Heidenhain thickness gauge. Prior to measurement, specimens were dried at 110°C for 4 hours under 150 mbar nitrogen pressure. Dynamic mechanical analysis was performed using a TA ARES testing system at a frequency of 1 Hz over the temperature range of -130°C to 250°C with a heating rate of 3°C / min. During the measurements, the storage modulus (G'), loss modulus (G''), and tangent delta (tanδ) were determined as a function of temperature.

[0063] [Weldability] Welding was performed on injection molded plaques measuring 80mm x 80mm x 1.0mm. Two plaques were placed on top of each other. Welding was performed with a 16KW RF welder with a vertical press setup. Electrode brass 75 x 10mm 2 The temperature of the main block was controlled at 200°F (93.3°C). The temperature of the contact plate was not controlled but was typically measured at 110°F (43.3°C). Each RF welding cycle consisted of a 1.0-second preheat, a 2.5-second current application, and a 2.0-second cooling cycle when pressure was applied. The current was controlled as a percentage of maximum power. A 180° peel test was performed to quantify the maximum peel force of the weld using the procedure described below. The welded plaques were placed in a room environment with a temperature range of 23 + / - 2°C and 50 + / - 10% RH for 3 days. 10-mm-wide plaques were marked with a marking pen and manually cut using scissors. Test parameters, including preload*, grip distance (50 mm), and test speed (50 mm / min), were entered into the software. The thickness and width of the specimen were measured and entered into the test software. The outer side of the unwelded portion of the bar was clamped between the grips, after which the peel test could begin. After the peel test, the specimens were removed from the grips. Test environment: 23 + / - 2°C, 50 + / - 10% relative humidity. The maximum peel force (in Newtons) is reported in Table 4. *Preload (value does not become zero after test begins): The exact value is based on the initial load of each specimen when the test bar is just clamped in the grips before the test begins.

[0064] [warp] For example, warpage was tested by cutting 100 mm x 40 mm specimens from a 4 mm extruded plate in the machine and counter-machine directions and at various locations across the width of the extruded plate, and exposing these test specimens to 100°C for 24 hours. Dimensional changes can be visually recorded and qualitatively evaluated. Ratings range from no warpage, thus completely flat, indicated by "+++," to curled edges, indicated by "+ / -," and finally, completely distorted, indicated by "---." The results are shown in Table 4.

[0065] [Chemical resistance] Chemical resistance was evaluated to assess the resistance of the compositions described in Examples 2 and 3. 1BA tensile bars were aged for 672 hours in 75% aqueous ethanol (23°C), 30% aqueous phosphoric acid (60°C), 3% aqueous phosphoric acid (60°C), 14% aqueous NaClO (23°C), 200 ppm aqueous NaClO (23°C), and 2000 ppm aqueous peracetic acid (23°C). No degradation of mechanical properties (measured by elongation at break) was observed in any of the above chemicals. Mechanical testing was performed according to ISO 527.

[0066] [Table 4]

[0067] Surprisingly, conveyor belts according to the invention having similar G' at room temperature, a measure of the stiffness of the belt, exhibited much higher tensile strength. Surprisingly, even the much softer extruded conveyor belt (Example 3) still exhibited high tensile strength combined with high peel strength indicated by high peel force. The conveyor belts according to the invention exhibited low camber and were therefore substantially flat combined with high peel strength.

Claims

1. 1. A conveyor belt comprising a composition, the composition comprising: a) a (co)polyester A comprising a hard segment comprising a polyester and having a melting temperature TmA of 200°C to 240°C, measured according to ISO 11357-1 / -3 (10°C / min), wherein the (co)polyester A is present in an amount of 1 to 60 wt%, based on the total weight of the composition; b) a copolyester B comprising a hard segment comprising a polyester, said copolyester B having a melting temperature TmB of 100°C to 180°C, measured in accordance with ISO 11357-1 / -3 (10°C / min), and said copolyester B being present in an amount of 40 to 99% by weight, relative to the total weight of the composition.

2. 2. The conveyor belt of claim 1, wherein the composition has a bimodal melting behavior exhibiting at least two peaks, one peak P1 between 200°C and 240°C, and another peak P2 between 100°C and 180°C.

3. 3. A conveyor belt according to claim 1 or 2, wherein TmA-TmB is at least 40°C and / or P1-P2 is at least 40°C.

4. 3. A conveyor belt according to claim 1 or 2, wherein TmA-TmB is at least 50°C and / or P1-P2 is at least 50°C.

5. 3. A conveyor belt according to claim 1 or 2, wherein TmA-TmB is at least 60°C and / or P1-P2 is at least 60°C.

6. 3. The conveyor belt according to claim 1 or 2, wherein the (co)polyester A and / or the copolyester B comprises a hard segment comprising polybutylene terephthalate (PBT).

7. 6. The conveyor belt according to claim 1, wherein the copolyester B comprises a soft segment selected from aliphatic polyesters, aliphatic polyethers, dimer fatty acids and dimer fatty diols, and combinations thereof.

8. 8. The conveyor belt of claim 7, wherein the aliphatic polyether is polytetramethylene oxide (PTMO).

9. 3. The conveyor belt according to claim 1, wherein the copolyester B further comprises polybutylene isophthalate (PBI) segments in an amount of 5 to 50% by weight, based on the total amount of the copolyester B.

10. The conveyor belt of any one of claims 1 to 9, wherein the composition further comprises a nucleating agent, glass fibers, a stabilizer, a colorant, and combinations thereof.

11. A conveyor belt according to any one of claims 1 to 10, wherein the (co)polyester A is polybutylene terephthalate (PBT).

12. A conveyor belt according to any one of claims 1 to 11, wherein the conveyor belt is an extruded conveyor belt.

13. At least the following steps: a) a (co)polyester A comprising a hard segment comprising a polyester and having a melting temperature TmA of 200°C to 240°C, measured according to ISO 11357-1 / -3 (10°C / min); providing a composition comprising a copolyester B hard segment comprising a polyester, said copolyester B having a melting temperature, TmB, measured according to ISO 11357-1 / -3 (10°C / min), of from 100°C to 180°C; providing a composition, wherein the (co)polyester A is present in an amount of 1 to 60 wt. %, relative to the total weight of the composition, and the copolyester B is present in an amount of 40 to 99 wt. %, relative to the total weight of the composition; b) bringing the composition to a temperature of 230°C to 290°C to form a melt; c) extruding the melt through a die; d) cooling the extruded melt to form a conveyor belt; A method for preparing a conveyor belt according to any one of claims 1 to 12, comprising the step of: e) optionally welding parts to said conveyor belt.

14. 14. The method of claim 13, wherein TmA-TmB is at least 40°C.

15. 14. The method of claim 13, wherein TmA-TmB is at least 50°C.

16. 14. The method of claim 13, wherein TmA-TmB is at least 60°C.

17. 17. The method of any one of claims 13 to 16, wherein copolyester B further comprises a soft segment selected from aliphatic polyesters, aliphatic polyethers, aliphatic polycarbonates, dimer fatty acids and dimer fatty diols, and combinations thereof.

18. The method according to any one of claims 13 to 17, wherein the composition of step a) is provided as a blend by mixing the (co)polyester A and the copolyester B as a dry blend.

19. 19. The method according to any one of claims 13 to 18, wherein a drying step is applied to (co)polyester A and / or copolyester B before bringing (co)polyester A and copolyester B to a temperature of 230°C to 290°C to form a melt.

20. At least the following steps: providing food products on a conveyor belt; - moving the conveyor belt together with the food product in a desired direction, A method for transporting food products, wherein the conveyor belt is a conveyor belt according to any one of claims 1 to 12.

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