Power transmission belt having dual modulus behavior during operation

Abstract

The present invention relates to a power transmission belt (P) comprising one or more reinforcing elements (R) embedded in a polymer composition (20). The transmission belt satisfies: - the ratio of the maximum tangential modulus MP2 generated by the transmission belt (P) in the range of 1% to 10% elongation to the tangential modulus MP1 generated by the transmission belt (P) in the range of 1% to 10% elongation, MP2 / MP1, is greater than or equal to 2.00; and - the force generated by the transmission belt (P) in the width of the transmission belt (P) in the range of 2% elongation is less than or equal to 120.0 daN / cm. The conveyor belt (P) is produced using a method comprising the following steps: immersing one or more reinforcing elements (R) in a polymer composition (20), followed by a curing step for forming the conveyor belt (P), wherein the reinforcing elements (R) satisfy: - the ratio MR2 / MR1 of the maximum tangential modulus MR2 generated by the reinforcing element (R) in the range of 1% to 10% elongation is greater than or equal to 2.00; and - the force generated by the reinforcing element (R) in the diameter of the reinforcing element in the range of 2% elongation is strictly less than 11.0 daN / mm.

Description

Technical Field

[0001] The field of this invention is power transmission belts, particularly those driven by friction. Background Technology

[0002] A power transmission belt comprising a conveyor belt fabric layer is known from the prior art (particularly from WO97 / 06297), the conveyor belt fabric layer including a reinforcing element comprising an assembly of three 168tex aramid multifilament yarns (known under the trade name Twaron 2100) and one 94tex nylon 6,6 multifilament yarn (known under the trade name Enka Nylon). The diameter of the reinforcing element is 0.85 mm, and at the diameter of the reinforcing element, the force generated by the conveyor belt fabric layer at 2% elongation is 12.0 daN / mm.

[0003] However, it is desirable to have a conveyor belt ply that is easy to install, i.e., exhibits sufficient elongation under low loads to be able to be installed on the conveyor belt, and when the ply is in operation, it is desirable to exhibit good torque transmission performance with low slippage and reduced creep.

[0004] In the prior art, application US20030171181 describes a conveyor belt with low initial modulus and elastic behavior, comprising conveyor belt fabric layers stacked at an angle. These have the disadvantage that the conveyor belt fabric layers must be cut, oriented, and stacked during manufacturing, and that the cut reinforcing elements are flush with the edges of the conveyor belt after fabrication, which poses a problem for the operational durability of the conveyor belt. Summary of the Invention

[0005] The object of this invention is to obtain a conveyor belt that is easy to install while exhibiting good torque transmission performance in a durable manner.

[0006] The subject of this invention is a power transmission belt comprising one or more reinforcing elements embedded in a polymer composition. The transmission belt satisfies:

[0007] - The ratio of the maximum tangential modulus MP2 generated by the conveyor belt within the 1% to 10% elongation range to the tangential modulus MP1 generated by the conveyor belt at 1% elongation, MP2 / MP1, is greater than or equal to 2.00; and

[0008] - The force generated by the conveyor belt at 2% elongation across its width is less than or equal to 120.0 daN / cm.

[0009] Power transmission belts can be understood as closed or open transmission belts. Transmission belts are preferably used with pulleys and sometimes with tensioning systems (such as tension rollers or pulley displacement). Closed or continuous transmission belts can be used for pulley systems with essentially fixed dimensions; open transmission belts (or jointless transmission belts) can be used by cutting and adapting them to the system dimensions, and then welding or reconnecting them through thermal effects and / or the addition of connectors. Flat friction power transmission belts with rectangular, trapezoidal (“V-belt”), hexagonal, or annular cross-sections exist; double or striped trapezoidal friction power transmission belts (“ribbed V-belts”) also exist in the length direction, which greatly increases the contact area between the pulleys and the transmission belt; it functions by gripping the pulleys with teeth. Friction power transmission belts with stripes in the transverse direction exist, which limit the energy dissipated by belt bending (“toothed transmission belts”). Transmission belts can be synchronized. A synchronized transmission belt is a toothed transmission belt that ensures transmission through interlocking rather than gripping.

[0010] Preferably, the power transmission belt is an elastic belt, thus having a low initial modulus of elasticity. These belts are easy to install, sometimes manually. They typically do not have a tensioning system, making implementation relatively simple. Depending on the belt length and the complexity of the tensioning system, the elastic belt needs to be elongated by 0.5% to 6%, and in most cases, between 1% and 3%. The tension generated by the belt at 2% elongation represents its ability to easily position itself in the pulley grooves.

[0011] Not limited to this purpose, these conveyor belts are particularly suitable for drive systems with pulleys positioned at fixed distances.

[0012] A reinforcing element is understood as an element used to mechanically reinforce a substrate, wherein the reinforcing element is intended to be embedded in the substrate.

[0013] In this specification, unless otherwise expressly stated, any range of values ​​expressed as “between a and b” means a range of values ​​from greater than “a” to less than “b” (i.e. excluding the endpoints a and b), while any range of values ​​expressed as “a to b” means a range of values ​​from “a” to “b” (i.e., including the strict endpoints a and b).

[0014] The compounds mentioned in the specification can be fossil-derived or bio-based. In the case of bio-based compounds, they can be partially or wholly derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the mentioned compounds can also be derived from the recycling of used materials, meaning they can be partially or wholly derived from recycling processes or obtained from raw materials that are themselves derived from recycling processes. This specifically relates to strands, yarns, polymers, plasticizers, fillers, etc.

[0015] Figure 5 The force / width-elongation curve of the conveyor belt according to the present invention is shown, in which the 2016 standard ASTM D 378 is applied. This standard is applied with the following modifications: the testing machine is equipped with two pulleys of 25.4 mm diameter adapted to the conveyor belt under test, preventing the conveyor belt from sticking to the jaws, and a tensile speed of 50.8 mm / min is used.

[0016] The maximum tangential modulus MP2 produced by the reinforcing element in the range of 1% to 10% elongation is understood as the maximum tangential modulus obtained by calculating the derivative of the force-elongation curve (obtained by applying the force / width-elongation curve obtained by applying the standard ASTM D 378 of 2016) in the range of 1% to 10% elongation.

[0017] The tangential modulus MP1 produced by the reinforcing element at 1% elongation is understood as the tangential modulus obtained by calculating the derivative of the force / width-elongation curve at 1% elongation (obtained by applying the standard ASTM D 378 of 2016).

[0018] The force generated by the conveyor belt at 2% elongation is understood as the force measured at 2%, which is obtained from the force / width-elongation curve (obtained by applying the 2016 standard ASTM D 378) corresponding to the 2% x-axis point of the same curve.

[0019] The range of the ratio of the maximum tangential modulus MP2 generated by the conveyor belt within the 1% to 10% elongation range to the tangential modulus MP1 generated by the conveyor belt at 1% elongation corresponds to the operating range in which drive torque can be transmitted during conveyor belt tensioning. As power transmission increases, slippage between the conveyor belt and pulleys leads to a decrease in transmission efficiency. The applicant observed that, through the bimodal behavior defined within this range, slippage is less under the same power transmission. Furthermore, over time, prior art elastic conveyor belts are prone to creep, i.e., plastically elongating irreversibly, rendering them inoperable. The applicant observed that, with the significant bimodal behavior within the aforementioned defined range, creep is greatly limited, thereby ensuring a longer service life for the conveyor belt. Over time, this creep leads to tension loss in the elastic conveyor belt. This bimodal behavior, expressed by a ratio MP2 / MP1 greater than or equal to 2.0 within the aforementioned defined range, makes it possible to reduce creep of the conveyor belt fabric layer under high torque transmission.

[0020] At the width of the conveyor belt, the force generated by the conveyor belt at 2% elongation is the force required to make it easy to install.

[0021] Advantageously, the force generated by the conveyor belt at 2% elongation is less than or equal to 100.0 daN / cm, preferably less than or equal to 80.0 daN / cm, across the width of the conveyor belt.

[0022] According to the present invention, a power transmission belt is obtained by a method comprising the steps of: embedding one or more reinforcing elements into a polymer composition, followed by a curing step for forming the transmission belt, wherein the reinforcing elements satisfy:

[0023] - The ratio of the maximum tangential modulus MR2 produced by the reinforcing element in the range of 1% to 10% elongation to the tangential modulus MR1 ​​produced by the reinforcing element at 1% elongation, MR2 / MR1, is greater than or equal to 2.00; and

[0024] - The force generated by the reinforcing element at 2% elongation is strictly less than 11.0 daN / mm across the diameter of the reinforcing element.

[0025] Figure 4 The force-elongation curves of prior art reinforcing elements and reinforcing elements according to the present invention are shown. The curves represent the situation occurring in a conveyor belt where the load on the conveyor belt is small when it is installed, i.e., it undergoes small deformation (elongation between 0% and 2%), while during operation the conveyor belt undergoes the maximum load, i.e., it undergoes elongation between 1% and 10%.

[0026] The maximum tangential modulus MR2 produced by the reinforcing element in the range of 1% to 10% elongation is understood as the maximum tangential modulus obtained by calculating the derivative of the force-elongation curve (obtained by applying the force-elongation curve obtained by applying the standard ASTM D885 / D 885M–10a of 2014) at 1% to 10% elongation after applying a standard tensile preload of 0.5 cN / tex to the reinforcing element.

[0027] The tangential modulus MR1 ​​produced by the reinforcing element at 1% elongation is understood as the tangential modulus obtained by calculating the derivative of the force-elongation curve (obtained by applying the force-elongation curve obtained by applying the standard ASTM D 885 / D 885M–10a of 2014) at 1% elongation after applying a standard tensile preload of 0.5 cN / tex to the reinforcing element.

[0028] In the case of reinforcing elements, the tangential modulus is measured directly prior to the step of embedding the reinforcing element into the conveyor belt fabric layer, that is, directly before any other steps occur between its final forming step (twisting or heat treatment) and the step of embedding into the polymer composition that alter the properties of the resulting tangential modulus.

[0029] The force generated by the reinforcing element at 2% elongation is understood as the force measured at 2% from the 2% x-axis point of the same curve (obtained under the conditions of the 2014 standard ASTM D885 / D 885M–10a), which occurs after a standard tensile preload of 0.5 cN / tex is applied to the reinforcing element.

[0030] By definition, the diameter of a reinforcing element is the diameter of the smallest circle circumscribed by the reinforcing element.

[0031] The range of the ratio of the maximum tangential modulus MR2 generated by the reinforcing element in the range of 1% to 10% elongation according to the invention to the tangential modulus MR1 ​​generated by the reinforcing element at 1% elongation corresponds to the operating range in which drive torque can be transmitted during the tensioning of the conveyor belt strands. As power transmission increases, slippage between the conveyor belt and the pulleys leads to a decrease in transmission efficiency. The applicant has observed that, with the bimodal behavior defined within this range, slippage is less under the same power transmission. Furthermore, over time, prior art elastic conveyor belts are prone to creep, i.e., plastically elongating irreversibly, rendering them inoperable. The applicant has observed that, with the significant bimodal behavior within the aforementioned defined range, creep is greatly limited, thereby ensuring a longer service life of the conveyor belt. Over time, this creep leads to tension loss in the elastic conveyor belt. This bimodal behavior, represented by a ratio MR2 / MR1 greater than or equal to 2 within the aforementioned defined range, makes it possible to reduce creep of the conveyor belt ply under high torque transmission.

[0032] At the diameter of the reinforcing element, the force generated by the reinforcing element at 2% elongation is the force required to ensure good installation of the conveyor belt.

[0033] Advantageously, the conveyor belt comprises a single conveyor belt fabric layer made of a polymer body 20, which includes a plurality of reinforcing elements. The reinforcing elements are arranged side by side and parallel to each other in a longitudinal direction X, which is substantially perpendicular to the general direction Y in which the reinforcing elements of the conveyor belt fabric layer extend.

[0034] Therefore, the conveyor belt is easier to manufacture as a single conveyor belt fabric layer, and the reinforcement is essentially at 0 degrees, exhibiting bidirectional elastic behavior.

[0035] Advantageously, each reinforcing element has an assembly comprising at least one aramid or aramid copolyamide multifilament and at least one aliphatic polyamide or polyester multifilament.

[0036] One effect of using a hybrid reinforcement element comprising at least one aramid or aramid copolyamide multifilament and at least one aliphatic polyamide or polyester multifilament is the achievement of a bimodal curve, meaning it exhibits a relatively low modulus at small deformations and a relatively high modulus at large deformations. Specifically, the conveyor belt ply exhibits a relatively low modulus at small deformations, controlled in this case by the modulus of the aliphatic polyamide multifilament, allowing for good installability. Furthermore, the conveyor belt reinforcement element exhibits a relatively high modulus at large deformations, controlled in this case by the modulus of the aramid or aramid copolyamide multifilament, which prevents slippage and allows for good torque transmission under high loads.

[0037] Regarding aramid or aramid copolyamide multifilament yarns, it should be recalled that, as is well known, they are filaments of linear macromolecules formed by aromatic groups bonded together by amide bonds, wherein at least 85% of the amide bonds are directly connected to two aromatic rings, and such filaments are more particularly filaments of fibers made of poly(p-phenylene terephthalamide) (or PPTA), which have long been produced by optically anisotropic spinning compositions. Among aramids or aramids, references may be made to polyarylamides (or PAA, especially known under the trademark name Ixef of Solvay), poly(m-phenylene adipamide), polyphthalamide (or PPA, especially known under the trademark name Amodel of Solvay), or para-aramid (or poly(p-phenylene terephthalamide) or PA PPD-T, especially known under the trademark name Kevlar of DuPont de Nemours or the trademark name Twaron of Teijin).

[0038] Aliphatic polyamide multifilament yarn is understood as a linear macromolecular filament of a polymer or copolymer containing amide functional groups, wherein the polymer or copolymer does not have an aromatic ring and can be synthesized by a polycondensation reaction between a carboxylic acid and an amine. Among aliphatic polyamides, nylon PA4.6, PA6, PA6.6, or PA6.10 may be mentioned, particularly Zytel from DuPont, Technyl from Solvay, or Rilsamid from Arkema.

[0039] Regarding polyester multifilament yarns, it should be recalled that they are filaments of linear macromolecules formed by groups linked together by ester bonds. The polyester is prepared by polycondensation through esterification between a dicarboxylic acid or its derivative and a diol. For example, polyethylene terephthalate can be prepared by polycondensation of terephthalic acid and ethylene glycol. Among known polyesters, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polypropylene terephthalate (PPT), or polypropylene naphthalate (PPN) may be mentioned.

[0040] Advantageously, the ratio MR2 / MR1 is greater than or equal to 2.50, preferably greater than or equal to 3.00.

[0041] Advantageously, the ratio MR2 / MR1 is less than or equal to 20.00, preferably less than or equal to 15.00.

[0042] Advantageously, the force generated by the reinforcing element (R) at 2% elongation is less than or equal to 8.0 daN / mm along the diameter of the reinforcing element (R).

[0043] Advantageously, the force generated by the reinforcing element (R) at 2% elongation is greater than or equal to 0.50 daN / mm, preferably greater than or equal to 1.00 daN / mm, over the diameter of the reinforcing element (R).

[0044] Advantageously, the conveyor belt is a friction-type power transmission belt.

[0045] Advantageously, the diameter of the reinforcing element is less than or equal to 2.00 mm, preferably less than or equal to 1.00 mm, and more preferably less than or equal to 0.50 mm.

[0046] In the first embodiment, each reinforcing element comprises an assembly consisting of a single strand of aramid or aramid copolyamide multifilament and a single strand of aliphatic polyamide or polyester multifilament, the strands being wound together in a spiral around each other.

[0047] Advantageously, each skeleton reinforcement element is twist-balanced.

[0048] Aroma polyamide or aramid copolyamide multifilament yarns and aliphatic polyesteramine or polyester multifilament yarns are assembled together and wound around each other in a spiral.

[0049] In a second embodiment, each reinforcing element comprises an assembly consisting of two strands of aramid or aramid copolyamide multifilament and a single strand of aliphatic polyamide or polyester multifilament, the strands being wound together in a helical manner to form a layer.

[0050] The phrase "component composed of..." is understood to mean that the component does not include multifilament yarns other than two strands of aramid or aramid copolyamide multifilament yarns and aliphatic polyamide multifilament yarns.

[0051] Advantageously, each skeleton reinforcement element is twist-balanced.

[0052] The following features apply to both implementation schemes described above.

[0053] The phrase "component composed of..." is understood to mean that the component does not include multifilament yarns other than two strands of aramid or aramid copolyamide multifilament yarns or polyester multifilament yarns.

[0054] In two embodiments of the invention, the expression "twist balance" is understood to mean that the multifilament strands are wound with substantially the same twist and that the twist of each monofilament strand in the final assembly is substantially zero. Specifically, methods well known in the art for manufacturing these skeleton reinforcement elements include a first step in which each yarn having a monofilament (more appropriately referred to as "yarn") is first independently twisted in a given direction D' = D1' = D2' = D3' (S or Z direction, according to accepted terminology, they respectively represent the orientation of the loop relative to the transverse bar as S or Z) (initial twist of R1', R2', R3', where R1' = R2' = R3') to form a strand or overtwist (more appropriately referred to as "ply") in which the monofilament is deformed into a helix around the axis of the strand. Then, in the second step, the strands are twisted together with a final twist R4 (satisfying R4 = R1' = R2' = R3') in a direction D4 (either the Z or S direction, respectively), opposite to the direction D' = D1' = D2' = D3', thus obtaining a reinforcing element (more appropriately called a "cord"). This reinforcing element is thus said to be twist-balanced because the individual filaments of the strands exhibit the same residual twist in the final reinforcing element (because R1' = R2' = R3'), and because R4 = R1' = R2' = R3' and the direction D' = D1' = D2' = D3' is opposite to the direction D4, the residual twist is zero or substantially zero. The expression "substantially zero residual twist" is understood to mean that the residual twist is strictly less than 2.5% of the twist R4.

[0055] Preferably, the count of the aramid or aramid copolyamide multifilament yarn is greater than or equal to 10 tex, and more preferably greater than or equal to 20 tex.

[0056] Preferably, the count of the aramid or aramid copolyamide multifilament yarn is less than or equal to 100 tex, more preferably less than or equal to 80 tex, and even more preferably less than or equal to 60 tex.

[0057] Preferably, the count of the aliphatic polyamide or polyester multifilament yarn is greater than or equal to 10 tex, and more preferably greater than or equal to 20 tex.

[0058] Preferably, the count of the aliphatic polyamide or polyester multifilament yarn is less than or equal to 100 tex, more preferably less than or equal to 80 tex, and even more preferably less than or equal to 60 tex.

[0059] The number of strands (or linear density) per strand is determined according to standard ASTM D1423. The number of strands is given in tex (weight of 1000m of product in grams - as a reminder: 0.111tex equals 1 denier).

[0060] Advantageously, the twist of each multifilament strand of the reinforcing element ranges from 200 turns / meter to 700 turns / meter, preferably from 250 turns / meter to 650 turns / meter.

[0061] The twist of the reinforcing element can be measured using any method known to those skilled in the art (e.g., according to the 2014 standard ASTM D 885 / D 885M–10a).

[0062] Advantageously, the density of reinforcing elements in the conveyor belt ranges from 96 to 250 reinforcing elements per decimeter of conveyor belt, preferably from 140 to 220 reinforcing elements per decimeter of conveyor belt.

[0063] The density of reinforcing elements in the conveyor belt ply is the number of reinforcing elements included in the conveyor belt ply per decimeter in a direction (X) perpendicular to the direction (Y) in which the reinforcing elements extend parallel to each other.

[0064] To effectively utilize the reinforcements while simultaneously allowing for the fabrication of the conveyor belt cord, the edge-to-edge distance between the reinforcement elements is typically 10% to 50% of the reinforcement element diameter. Using 30% of the diameter as a typical value, for reinforcement element diameters ranging from 0.3 mm to 0.8 mm, the conveyor belt cord has a density of 96 to 250 filaments / dm, which allows for the fabrication of the conveyor belt cord for use in power transmission belts. Those skilled in the art can set this value based on manufacturing constraints (viscosity of the polymer composition) or conditions of use.

[0065] Preferably, the polymer composition is a polyurethane-type composition.

[0066] As is well known to those skilled in the art, polyurethane-type compositions consist of diisocyanate-terminated prepolymers that are cured with diamines or diols and can be extended with other polymeric diols or diamines. Optional additives may be included to impart various properties, including curing catalysts, plasticizers, antistatic agents, colorants, and fillers; this list is not limiting.

[0067] Advantageously, the reinforcing elements are arranged in an alternating Z and S twist in a direction (X) perpendicular to the direction of the conveyor belt (Y).

[0068] In the first alternative form, the conveyor belt has a continuous shape, and its external geometry is trapezoidal, trapezoidal with longitudinal or transverse stripes or ribs, circular, semi-circular, rectangular, or a combination thereof.

[0069] In the second alternative form, the conveyor belt is of a welded, jointless type, and its external geometry is rectangular, trapezoidal, trapezoidal with longitudinal or transverse stripes or ribs, circular, semi-circular, rectangular, or a combination thereof.

[0070] exist Figure 6 The power transmission belt having a semi-circular or rectangular shape according to the invention is described in particular by way of illustration. Attached Figure Description

[0071] The invention will be better understood from the following description, given only by way of non-limiting embodiments and with reference to the accompanying drawings, in which:

[0072] - Figure 1 A power transmission belt P according to the present invention is depicted;

[0073] - Figure 2 It shows Figure 1 Polymer body 20 in;

[0074] - Figure 3 The force measurement test is shown;

[0075] - Figure 4 The force-elongation curves of the reinforcing element EC of a prior art transmission belt and the reinforcing elements R1, R3, R4 and R5 of a transmission belt according to the present invention are shown.

[0076] - Figure 5 The force-elongation curve of the transmission belt P4 according to the present invention is shown; and

[0077] - Figure 6 Other power transmission belts according to the invention are depicted. Detailed Implementation Plan

[0078] According to an embodiment of the transmission belt P4 of the present invention

[0079] Figure 1A continuous power transmission belt P according to the invention is shown, its external geometry being trapezoidal. The power transmission belt P is intended for driving the rotation of any component. The power transmission belt P comprises a polymer body 20 made of a polyurethane matrix with reinforcing elements R embedded to form a transmission belt fabric layer. The power transmission belt P also includes a mechanical drive layer 22 in contact with the polymer body 20, the mechanical drive layer 22 also being made of polyurethane. The mechanical drive layer 22 is provided with a plurality of ribs 24, each rib 24 extending along a general direction Y substantially perpendicular to the longitudinal direction X of the transmission belt P. Each rib 24 has a trapezoidal cross-section. The general directions of the ribs 24 are substantially parallel to each other. The ribs 24 extend along the entire length of the transmission belt P. These ribs 24 are intended to engage in grooves or slots having complementary shapes, which are carried, for example, by pulleys on which the transmission belt is intended to be mounted.

[0080] In this case, the transmission belt P is the transmission belt P4 with the reinforcing element R4.

[0081] Now refer to Figure 2 To describe Figure 1 The polymer matrix 20 in the example. Figure 2 As shown, the conveyor belt P includes a single conveyor belt fabric layer N4 composed of a polymer body 20, the polymer body 20 including a plurality of reinforcing elements R4.

[0082] The polymer body 20 includes a plurality of reinforcing elements R4. The reinforcing elements are arranged side by side and parallel to each other in a longitudinal direction X, which is substantially perpendicular to the overall direction Y in which these reinforcing elements extend in the conveyor belt ply.

[0083] The power transmission belt P4 satisfies the following: the ratio of the maximum tangential modulus MP2 generated by the transmission belt P4 in the range of 1% to 10% elongation to the tangential modulus MP1 generated by the transmission belt P4 at 1% elongation is greater than or equal to 2.00, in which case MP2 / MP1 = 3.5; the force generated by the transmission belt P4 at 2% elongation is less than or equal to 120.0 daN / cm, preferably less than or equal to 100.0 daN / cm, and even more preferably less than or equal to 80.0 daN / cm, in which case F at 2% elongation = 74.7 daN / cm.

[0084] The following describes the transmission belt reinforcement element R4 and its corresponding components.

[0085] Properties of the strands of the reinforcing element

[0086] like Figure 2As schematically shown, the reinforcing element R4 comprises an assembly consisting of one aramid or aramid copolyamide multifilament strand and one aliphatic polyamide multifilament strand, the two strands being wound together in a helical manner. The conveyor belt reinforcing element P4 is twist-balanced.

[0087] In this case, the selected aramid is preferably para-aramid known by the trade names Twaron 1000 or Twaron 2040 from Teijin Corporation.

[0088] The aliphatic polyamide is nylon known by the trade name TYP632 470f68 from Nexis.

[0089] Number of reinforcing elements R4

[0090] In the reinforcing element, the count of the aramid or aramid copolyamide strands is greater than or equal to 10 tex, preferably greater than or equal to 20 tex, and less than or equal to 100 tex, preferably less than or equal to 80 tex, and more preferably less than or equal to 60 tex. In this case, the count of the aramid strands is equal to 55 tex.

[0091] In the reinforcing element, the aliphatic polyamide strand count is greater than or equal to 20 tex, preferably greater than or equal to 30 tex, more preferably greater than or equal to 40 tex, and less than or equal to 100 tex, preferably less than or equal to 80 tex, more preferably less than or equal to 60 tex. In this case, the nylon strand count is equal to 47 tex.

[0092] Twist of reinforcing element R4

[0093] In the reinforcing element R4, the twist of each multifilament strand ranges from 240 turns / meter to 700 turns / meter, preferably from 250 turns / meter to 650 turns / meter. In this case, the twist of each multifilament strand in the reinforcing element R4 is equal to 350 turns / meter.

[0094] The diameter of the reinforcing element R4 is less than or equal to 2.0 mm, preferably less than or equal to 1.00 mm, and more preferably less than or equal to 0.60 mm. In this case, the diameter D of the reinforcing element R4 is 0.43 mm.

[0095] Force-elongation curve of reinforcement R4

[0096] The ratio MR2 / MR1, which is the maximum tangential modulus MR2 produced by the reinforcing element R4 in the range of 1% to 10% elongation, is greater than or equal to 2.00, preferably greater than or equal to 2.50, and more preferably greater than or equal to 3.00; this ratio MR2 / MR1 is less than or equal to 20.00, preferably less than or equal to 15.00. In this case, MR2 / MR1 = 9.3.

[0097] The force generated by the reinforcing element R4 at 2% elongation along the diameter of the reinforcing element is strictly less than 11.00 daN / mm, preferably less than or equal to 8.00 daN / mm; this force is greater than or equal to 0.50 daN / mm, preferably greater than or equal to 1.00 daN / mm. In this case, the force generated by the reinforcing element R4 at 2% elongation along the diameter of the reinforcing element is equal to 2.3 daN / mm.

[0098] Geometric features of conveyor belt fabric layer N4

[0099] The density of reinforcing elements R4 in the transmission belt P4 ranges from 96 to 250 reinforcing elements / decimeter of transmission belt P4, preferably from 140 to 220 reinforcing elements / decimeter of transmission belt P4. In this case, the density of reinforcing elements R4 is equal to 179 reinforcing elements R4 / decimeter of transmission belt P4.

[0100] Method for manufacturing reinforcing element R4

[0101] As described above, the reinforcing element R4 is twist-balanced, meaning that the two multifilament strands are wound with substantially the same twist and the twist of the monofilament in each multifilament strand is substantially zero. In one embodiment, in a first step, each yarn having a monofilament (more appropriately referred to as "yarn") is first independently twisted itself in a given direction (in this case, the Z direction) with an initial twist of 350 twists / meter to form a ply or overtwist (more appropriately referred to as "ply"). Then, in the second step, the two ply are twisted together in the S direction with a final twist of 350 turns / meter to obtain the assembly of the reinforcing element (more appropriately referred to as "cord").

[0102] In another embodiment, in the first step, each yarn having a monofilament is first independently twisted in a given direction (in this case, the S direction) with an initial twist of 350 turns / meter to form a ply or overtwist. Then, in the second step, the two plies are twisted together in the Z direction with a final twist of 350 turns / meter to obtain an assembly of reinforcing elements.

[0103] Method for manufacturing a conveyor belt according to the present invention

[0104] The methods used to manufacture conveyor belts are those commonly used by those skilled in the art.

[0105] The conveyor belt P4 is manufactured by embedding multiple reinforcing elements R4 into a polymer composition, wherein the reinforcing elements, assembled in the S and Z directions according to the above embodiment, are inserted into a mold. In the embedding step, the reinforcing elements are embedded into the polymer composition, for example, into polyurethane. Finally, the resulting green form is crosslinked to obtain the conveyor belt P4.

[0106] Measurement and comparison tests

[0107] As comparative examples, two existing technology transmission belts, designated PEDT and PC respectively, were used. Three contrasting transmission belts, C1, C2, and C3, were also used.

[0108] The geometric features of transmission belts C1, C2 and C3, prior art transmission belts (PEDT and PC), and transmission belts P1 to P6 according to the present invention are summarized in Tables 1 and 2 below.

[0109] Tables 1 and 2 below also show the results of the installability of the conveyor belt, i.e., the elongation under low load, so that it can be installed on the pulley.

[0110] The term NC means that no measurement was taken on these various different transmission belts.

[0111] [Table 1]

[0112]

[0113]

[0114] [Table 2]

[0115]

[0116]

[0117] Comparison of conveyor belts

[0118] To conduct comparative analysis of the conveyor belts, force tests were performed on the machine, such as... Figure 3 As shown. The principle of these tests is to drive a transmission belt using two pulleys, one with driving torque and the other with braking torque. The transmitted torque is the difference between these two torques, and the slip is the difference in rotational speed between the two pulleys. Different tests were conducted at a speed of 1750 rpm.

[0119] Three different force tests were conducted:

[0120] - In the first variant, the pulleys are free to move relative to each other, and the applied tensile preload PT of 22.7 kg remains fixed during the test. In this case, by applying a torque of 2.71 Nm for 100 hours, the change in the position of the pulleys over time can be monitored, thereby monitoring the elongation of the transmission belt (in percentage).

[0121] - In the second variant, the pulley distance remains constant, and the initial applied tensile preload PT is 22.7 kg. Therefore, by applying a fixed torque of 2.71 Nm to the conveyor belt for 100 hours, the decrease in tension on the conveyor belt over time (in percentage) compared to the tensile preload PT can be monitored.

[0122] - Finally, a third variant was developed in a configuration where the pulleys can move freely relative to each other. A tensile preload of 22.7 kg was applied, with a torque variation ranging from 2.71 Nm to 7.45 Nm. Slippage, i.e., the change in rotational speed between the drive pulley and the brake pulley, was measured. Under normal operating conditions, slippage was less than 5%, preferably less than 3%.

[0123] The results are summarized in Table 3 below.

[0124] Table 3 shows the resistance of the transmission belt to tension drop tested in tests using a fixed pulley. Good resistance to tension drop is indicated by the lowest value for each period, measured as a percentage of tension loss between 100 seconds and 400,000 seconds. The table also shows resistance to creep, i.e., resistance to elongation between 10,000 seconds and 400,000 seconds in tests using a movable pulley with applied tension.

[0125] Similarly, the maximum permissible torques for achieving slippage of less than 5% and less than 10% are shown, with the highest value representing good torque transfer between the drive pulley and the brake pulley.

[0126] [Table 3]

[0127]

[0128] These results demonstrate that the conveyor belts P4 and P5 according to the present invention exhibit greater resistance to tension drop than the prior art conveyor belt NC and the control conveyor belt C3, and their creep resistance is significantly better than that of the prior art conveyor belt NC. For a given slip level (5% or 10%), conveyor belts P4 and P5 also exhibit a greater ability to transmit large torques.

[0129] Therefore, the conveyor belt according to the invention exhibits very good resistance to tension drop, improved creep resistance, and improved ability to transmit mechanical torque.

[0130] Therefore, as the results above show, the present invention clearly lies in a power transmission belt comprising one or more reinforcing elements embedded in a polymer composition. This transmission belt satisfies:

[0131] - The ratio of the maximum tangential modulus MP2 generated by the conveyor belt within the 1% to 10% elongation range to the tangential modulus MP1 generated by the conveyor belt at 1% elongation, MP2 / MP1, is greater than or equal to 2.00; and

[0132] - On the width of the conveyor belt, the force generated by the conveyor belt (P) at 2% elongation is less than or equal to 120.0 daN / cm.

[0133] The present invention is not limited to the embodiments described above.

[0134] Features of the different implementation schemes and variants described or envisioned above can also be combined, as long as they are compatible with each other according to the present invention.

Claims

1. A power transmission belt (P), said power transmission belt (P) comprising one or more reinforcing elements (R) embedded in a polymer composition (20), characterized in that, The transmission belt (P) satisfies: - The ratio of the maximum tangential modulus MP2 produced by the conveyor belt (P) within the range of 1% to 10% elongation to the tangential modulus MP1 produced by the conveyor belt (P) at 1% elongation, MP2 / MP1, is greater than or equal to 2.00; and - On the width of the conveyor belt (P), the force generated by the conveyor belt (P) at 2% elongation is less than or equal to 120.0 daN / cm; The conveyor belt (P) is obtained by a method comprising the following steps: embedding one or more reinforcing elements (R) into a polymer composition (20), followed by a curing step for forming the conveyor belt (P), wherein the reinforcing elements (R) satisfy: - The ratio MR2 / MR1 of the maximum tangential modulus MR2 produced by the reinforcing element (R) in the range of 1% to 10% elongation to the tangential modulus MR1 ​​produced by the reinforcing element (R) at 1% elongation is greater than or equal to 2.00; and - On the diameter of the reinforcing element, the force generated by the reinforcing element (R) at 2% elongation is strictly less than 11.0 daN / mm.

2. The transmission belt (P) according to claim 1, wherein, At the width of the conveyor belt (P), the force generated by the conveyor belt (P) at 2% elongation is less than or equal to 100.0 daN / cm.

3. The transmission belt (P) according to claim 1, wherein, Each reinforcing element (R) has an assembly comprising at least one aramid or aramid copolyamide multifilament and at least one aliphatic polyamide or polyester multifilament.

4. The transmission belt (P) according to claim 1, wherein, The ratio MR2 / MR1 is greater than or equal to 2.

50.

5. The transmission belt (P) according to claim 1, wherein, The ratio MR2 / MR1 is less than or equal to 20.

00.

6. The transmission belt (P) according to claim 1, wherein, The force generated by the reinforcing element (R) at 2% elongation is less than or equal to 8.0 daN / mm along the diameter of the reinforcing element (R).

7. The transmission belt (P) according to claim 1, wherein, On the diameter of the reinforcing element (R), the force generated by the reinforcing element (R) at 2% elongation is greater than or equal to 0.50 daN / mm.

8. The transmission belt (P) according to claim 1, wherein, The transmission belt (P) is a friction-type power transmission belt.

9. The transmission belt (P) according to claim 1, wherein, The diameter of the reinforcing element (R) is less than or equal to 2.00 mm.

10. The transmission belt (P) according to claim 1, wherein, Each reinforcing element (R) comprises an assembly consisting of a single strand of aramid or aramid copolyamide multifilament and a single strand of aliphatic polyamide or polyester multifilament, which are wound together in a spiral around each other.

11. The transmission belt (P) according to claim 1, wherein, Each reinforcing element (R) comprises an assembly consisting of two strands of aramid or aramid copolyamide multifilament and a single strand of aliphatic polyamide or polyester multifilament, which are wound together in a spiral to form a layer.

12. The transmission belt (P) according to claim 1, wherein, The width of the conveyor belt (P) has 96 to 250 reinforcing elements per decimeter of conveyor belt (P).

13. The transmission belt (P) according to claim 1, wherein, The polymer composition is a polyurethane type composition.

14. The transmission belt (P) according to claim 1, wherein, The reinforcing elements (R) are arranged in alternating Z and S twists in a direction (X) perpendicular to the direction (Y) of the conveyor belt (P).

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