Friction reduced materials

Abstract

To provide a thermoplastic composition for use in a sliding element that exhibits desirable properties of sliding and wear characteristics while reducing or solving one or more of the problems of the materials.SOLUTION: The invention relates to a thermoplastic composition for use in a sliding element comprising a first polyamide being a polyamide of AA-BB, a second polyamide being a polyamide of AB type and a functional group-modified polyolefin. The invention also relates to a sliding element comprising the thermoplastic composition. The invention further relates to a sliding element comprising the thermoplastic composition for use in a lubricated sliding system, for example in a chain transmission apparatus.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic composition for use in a sliding element. The present invention also relates to a sliding element for use in a sliding system, particularly an oil-lubricated sliding system. Specifically, the present invention relates to a sliding element for use in a chain transmission including a sliding part for sliding engagement with a chain, the sliding part being made primarily from the above-described thermoplastic composition. The present invention also relates to an engine including a first sliding element in sliding contact with a second element, at least the sliding part being made primarily from the above-described thermoplastic composition. The present invention further relates to a chain transmission including a chain and a sliding element including (i) a sliding part in sliding engagement with the chain, and (ii) a body that reinforces and supports the sliding part, the sliding part being made primarily from the above-described thermoplastic composition. [Background technology]

[0002] Recently, there has been increasing concern in the automotive industry regarding energy consumption, specifically CO2 emissions, of personal passenger cars and other transportation vehicles. From an environmental conservation perspective, improvements in fuel economy or fuel consumption of internal combustion engines are required. To enforce the reduction of CO2 emissions, government agencies have established or are inclined to establish penalties for excessive CO2 emissions. Therefore, and particularly for reasons of a more sustainable environment, there is a need for more fuel-efficient passenger cars and for more fuel-efficient engines for use in such cars and other transportation vehicles.

[0003] One of the main causes of high energy consumption in automobiles is energy loss due to friction. One significant area of ​​friction is in engines that include chain drive systems, where components including sliding elements come into sliding contact with the chain during actual engine use.

[0004] In recent years, there has already been much interest in improving the properties of sliding parts such as bearings, rollers, gears, etc., in order to reduce noise associated with sliding, reduce weight, and provide lubrication to the sliding parts, especially when plastic sliding materials are used in increasingly severe environments, for example, under high bearing pressures and high operating temperatures.

[0005] In particular, the sliding elements of chain guides and chain tensioners used in automobile internal combustion engines are required to have good sliding characteristics, good heat resistance at high temperatures such as temperatures in the range of 60°C to 150°C, good oil resistance, good wear resistance, good fatigue resistance, and good impact resistance.

[0006] Due to their good performance in heat resistance, oil resistance and mechanical strength, polyamide polymers are often used in sliding elements, at least for the part of the sliding element that is in sliding engagement with the second element.

[0007] However, these polyamide polymers are not always suitable for applications where wear and friction resistance are important properties. To improve the friction resistance of these polyamide polymers during sliding, solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2), or graphite have typically been added. However, the improvement in friction caused by the addition of these solid lubricants has been found to be limited. Furthermore, the addition of these solid lubricants often reduces the processability of the resulting material and its mechanical and physical properties, which is undesirable from the perspective of the reliability of parts manufactured from the material. In addition, when fluorinated additives are used, they have the disadvantage of being environmentally unfriendly.

[0008] Thus, although improvements have been made in the development of materials for use in sliding elements, there remains a need for further improvements. Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention, among other goals, to provide a thermoplastic composition for use in sliding elements that reduces or overcomes one or more of the above-mentioned material problems while exhibiting desirable sliding and wear properties.

[0010] This objective has been achieved with the thermoplastic compositions described herein below. [Means for solving the problem]

[0011] The present invention relates to a thermoplastic composition for use in a sliding element, comprising 60 to 95 wt. % of a first polyamide (a) which is an AA-BB type polyamide, 0.5 to 10 wt. % of a second polyamide (b) which is an AB type polyamide, and 0.5 to 35 wt. % of a functionally modified polyolefin (c), wherein the wt. % are based on the total weight of the thermoplastic composition.

[0012] The present invention further relates to a sliding element comprising the above-described thermoplastic composition.

[0013] The invention further relates to a sliding element, such as that included in a chain guide or chain tensioner, for use in a lubricated sliding system.

[0014] The present invention further relates to a sliding element for use in a chain transmission including a sliding contact part for sliding engagement with a chain, the sliding contact part being made primarily from the above-described thermoplastic composition.

[0015] The present invention further relates to an engine including a first sliding element in sliding contact with a second element, wherein at least the sliding contact portion is made primarily of the thermoplastic composition described above.

[0016] The present invention further relates to a chain transmission device including a chain and (i) a sliding part in sliding engagement with the chain, and (ii) a sliding element including a body that reinforces and supports the sliding part, wherein the sliding part is made primarily of the above-described thermoplastic composition. [Brief explanation of the drawings]

[0017] [Figure 1] Figure 1 shows the measurement of the coefficient of friction (CoF) in a chain-on-guide test. [Figure 2] 1 shows the measurement of the coefficient of friction (CoF) in the ball-on-pyramid test. DETAILED DESCRIPTION OF THE INVENTION

[0018] Throughout this specification and the appended claims, the words "comprise," "include," and "having," as well as variations such as "comprises," "comprising," "includes," and "including," are intended to be interpreted inclusively, that is, these words are intended to convey the possible inclusion of other elements or integers not specifically recited, where the context allows.

[0019] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., one or at least one) of the grammatical object of the article. By way of example, "an element" may mean one element or more than one element.

[0020] In connection with the present invention, it has surprisingly been found that thermoplastic compositions comprising two types of polyamides and modified polyolefins exhibit very good processability and impart excellent sliding properties to molded parts made therefrom, in combination with advantageous wear resistance and mechanical properties (such as impact resistance, stiffness, and ductility), i.e., when the sliding element comprises the thermoplastic composition, the thermoplastic composition imparts improved performance to the sliding element.

[0021] It is therefore an object of the present invention to provide a novel thermoplastic composition for use in sliding elements.

[0022] A further object of the present invention is to provide a sliding element comprising the above thermoplastic composition.

[0023] It is a further object of the present invention to provide a sliding element comprising the above thermoplastic composition for use in a lubricated sliding system, such as a chain guide or chain tensioner.

[0024] It is a further object of the present invention to provide a sliding element for use in a chain transmission device including a sliding contact part for sliding engagement with a chain, the sliding contact part being made primarily from the above-described thermoplastic composition.

[0025] A further object of the present invention is to provide an engine including a first sliding element in sliding contact with a second element, wherein at least the sliding contact portion is made primarily of the above-described thermoplastic composition.

[0026] It is a further object of the present invention to provide a chain transmission device including a chain and (i) a sliding contact portion in sliding engagement with the chain, and (ii) a sliding element including a body for strengthening and supporting the sliding contact portion, wherein the sliding contact portion is made primarily of the above-described thermoplastic composition.

[0027] The thermoplastic composition for use in the sliding element of the present invention comprises 60 to 95 wt. % of a first polyamide (a) which is an AA-BB type polyamide, 0.5 to 10 wt. % of a second polyamide (b) which is an AB type polyamide, and 0.5 to 35 wt. % of a functionally modified polyolefin (c), where the wt. % are based on the total weight of the thermoplastic composition.

[0028] It is to be understood that in the context of the present invention, "sliding element" includes a "sliding portion" which is a part of a sliding element that is in sliding and / or rolling engagement with (or intended to be in sliding and / or rolling engagement with) a sliding portion of another sliding element, and for that reason the sliding portion must have low friction characteristics.

[0029] As used herein, a "polyamide" is a polymer comprising monomer building blocks linked together by amide functionality (Kunststoff Handbuch; G.W. Becker, D. Braun, eds; 1998; vol. 3 / 4; Polyamide). Polyamides typically have a viscosity number (measured according to ISO 307) of 50 to 250 g / ml. The term "polyamide" is to be interpreted broadly and includes polyamides, copolyamides, or mixtures thereof.

[0030] As used herein, "AA-BB type polyamide" or "AA-BB polyamide" or "AA-BB type polyamide" is based primarily on diamines (AA-type monomers) and dicarboxylic acids (BB-type monomers). The polyamide may contain additional difunctional units (e.g., difunctional units derived from α,ω-amino acids or lactam derivatives thereof). However, the content of such additional difunctional units is generally less than 20 mol%, where mol% is based on the total molar amount of difunctional units in the polyamide. Preferably, the content of such additional difunctional units is generally less than 10 mol%, where mol% is based on the total molar amount of difunctional units in the polyamide.

[0031] As used herein, "AB-type polyamide" or "AB polyamide" or "AB-type polyamide" is based on AB repeating units derived primarily from α,ω-amino acids and their lactam derivatives (AB monomers). The polyamide may contain additional difunctional units derived from other components. However, the content of such additional difunctional units is generally less than 20 mol%, where mol% is based on the total molar amount of difunctional units in the polyamide. Preferably, the content of such additional difunctional units is generally less than 10 mol%, where mol% is based on the total molar amount of difunctional units in the polyamide.

[0032] As used herein, a "polyolefin" is a polymer made from olefins (i.e., alkenes) as monomers. The term "polyolefin" is intended to be broadly interpreted and includes polymers and copolymers of one or more olefins, as well as mixtures thereof. Examples of olefins are ethylene, propylene, butene, and pentene.

[0033] In this specification, "functionally modified polyolefin" (also referred to as "functionally grafted polyethylene" or "modified polyolefin" or "grafted polyolefin") is understood as a polyolefin that has been modified (grafted) with functional groups capable of reacting with the end groups and / or backbone amide groups (i.e. reactive chemical groups) of polyamides. In the context of the present invention, the term "unmodified polyolefin" (also referred to as "polyolefin") is understood as a polyolefin that has not yet been modified (grafted) with such functional groups.

[0034] As used herein, all ranges given as "x to y" are understood to run from x to y and include the values ​​x and y.

[0035] As used herein, all ranges expressed as "greater than x," "greater than x," "below x," or "less than x" are understood to exclude the value of x.

[0036] The thermoplastic composition of the present invention comprises a first polyamide (a) which is an AA-BB type polyamide, and a second polyamide (b) which is an AB type polyamide.

[0037] In one embodiment of the present invention, the first polyamide (a) of AA-BB type is a semi-crystalline polyamide having a melting temperature (Tm-1) and the second polyamide (b) of AB type is a semi-crystalline polyamide having a melting temperature (Tm-2), where Tm-2 is at least 20° C. lower than Tm-1. More preferably, Tm-2 is at least 30° C. lower than Tm-1, more preferably at least 40° C., even more preferably at least 50° C., even more preferably at least 60° C., and most preferably at least 70° C. lower than Tm-1.

[0038] In a preferred embodiment of the invention, the first polyamide (a) of AA-BB type has a Tm-1 of at least 230°C, preferably at least 240°C, more preferably at least 250°C, more preferably at least 260°C, also more preferably at least 270°C, even more preferably at least 280°C, still more preferably at least 290°C and most preferably at least 300°C.

[0039] In this specification, melting temperature is understood to be the temperature on a sample pre-dried in a N atmosphere at a heating and cooling rate of 10°C / min, measured by the DSC method according to ISO-11357-1 / 3, 2011. In this specification, Tm is calculated from the peak value of the highest melting peak in the second heating cycle.

[0040] In another embodiment of the invention, the first polyamide (a) of AA-BB type includes aliphatic and semi-aromatic polyamides, as well as copolyamides and mixtures thereof.

[0041] Specifically, suitable aliphatic polyamides for the first polyamide (a) may be PA28, PA210, PA212, PA214, PA216, PA218, PA46, PA48, PA410, PA412, PA414, PA56, PA62, PA66, PA68, PA6CHDA, PA82, PA86, PA102, PA106, PA122, PA126, PA142, PA162, PA182, PA10CHDA, copolyamides and mixtures thereof. Suitable aliphatic copolyamides of the first polyamide (a) may be PA46 / 66, PA6 / 66, PA66 / 11, PA66 / 12, PA6 / 610, PA66 / 610, PA46 / 6, PA6 / 66 / 610, copolyamides obtained from 1,4-cyclohexanedicarboxylic acid (CHDA) and 2,2,4- and 2,4,4-trimethylhexamethylenediamine, copolyamides obtained from any dicarboxylic acid and isophoronediamine, 4,4-diaminodicyclohexylmethane and / or 3,5-dimethyl-4,4-diamino-dicyclohexylmethane, copolyamides and mixtures thereof.

[0042] More specifically, suitable semi-aromatic polyamides for the first polyamide (a) include PA4T, PA5T, PA6T, PA9T, PA10T, PA12T, PA-MXD6, PA-PXD6 (wherein PXD6 is p-xylylenediamine), PA4T / 6T, PA10T / 106, PA10T / 5T, PA10T / 9T, PA10T / 1012, PA10T / NDT / INDT, PA10T / 11, PA10T / MACMT, PA10T / MACMT, PA10T / PACMT, PA6T / 4T, PA6T / 4T / 66, PA6T / 4T / DT, PA6T / 4T / DT / DI, PA6T / 4T / 6I, PA6T / 1 0T, PA6T / 6I, PA6T / NDT / INDT, PA6T / MACMT, PA6T / 4T / MACMT, PA6T / PACMT, PA6T / 4T / PACMT, PA6T / MXDT, PA6T / 1,3-BACT (where 1,3-BAC is hydrogenated MXD), PA6T / DT-copolyamide with D=2-methylpentamethylenediamine, PA4T / 6, PA4T / 66, PA4T / 46, PA4T / 410, PA6I, PA6I copolyamides obtained from caprolactam, isophthalic acid and / or terephthalic acid, and PACM; copolyamides obtained from caprolactam, isophthalic acid and / or terephthalic acid, and isophorone diamine; copolyamides obtained from isophthalic acid and / or terephthalic acid and / or other aromatic or aliphatic dicarboxylic acids, optionally alkyl-substituted hexamethylenediamine and alkyl-substituted PACM; copolyamides of the above polyamides; and mixtures thereof.

[0043] Preferably, the first polyamide (a) of AA-BB type is chosen from PA66, PA46, PA410, PA412, PA5T, PA6T, PA6T, PA6T / 6I, PA6T / 66, PA6T / 6, PA6T / 4T, PA6 / 66, PA66 / 6T / 6I, PA6T / DT-copolyamide, PA9T, PA9T / 2-MOMDT-copolyamide, PA10T, PA10T / 106, PA10T / 6T, PA46 / 6, copolyamides or mixtures thereof.

[0044] More preferably, the first polyamide (a) of AA-BB type is chosen from PA6T / 4T, PA6T / 4T / 66, PA6T / 4T / DT, PA6T / 4T / DT / DI, PA6T / 4T / 6I, PA6T / 6I, PA66, PA6T / 66, PA6T / 66 / 6I, PA6T / DT, PA9T, PA9T / 2-MOMDT, PA10T, PA10T / 106, PA10T / 6T, PA46, copolyamides or mixtures thereof.

[0045] Even more preferably, the first polyamide (a) of AA-BB type is chosen from PA6T / 4T, PA6T / 4T / 66, PA6T / 4T / DT, PA6T / 4T / DT / DI, PA6T / 4T / 6I, PA6T / 6I, PA66, PA6T / 66, PA6T / 66 / 6I, PA6T / DT, PA9T, PA9T / 2-MOMDT, PA46, copolyamides or mixtures thereof.

[0046] Even more preferably, the first polyamide (a) of AA-BB type is chosen from PA6T / 4T, PA6T / 4T / 66, PA6T / 4T / DT, PA6T / 4T / DT / DI, PA6T / 4T / 6I, PA6T / 6I, PA6T / 66, PA6T / 66 / 6I, PA6T / DT, PA9T, PA9T / 2-MOMDT, PA46, copolyamides or mixtures thereof.

[0047] In another embodiment of the invention, the second polyamide (b) of AB type includes aliphatic polyamides, as well as copolyamides and mixtures thereof.

[0048] In particular, the second polyamide (b) of AB type is selected from PA6, PA7, PA8, PA9, PA10, PA11, PA12, copolyamides or mixtures thereof.

[0049] More specifically, the second polyamide (b) of AB type is chosen from PA6, PA9, PA10, PA11, PA12, copolyamides or mixtures thereof.

[0050] Even more particularly, the second polyamide (b) of AB type is chosen from PA6, PA11, PA12, copolyamides or mixtures thereof.

[0051] Preferably, the AB-type second polyamide (b) comprises PA6 or a copolyamide thereof. More preferably, the second polyamide (b) comprises at least 80 mol% PA6, specifically at least 85 mol% PA6, more specifically at least 90 mol%, even more specifically at least 95 mol% PA6, and most specifically at least 98 mol% PA6. Most preferably, the AB-type second polyamide (b) is PA6.

[0052] In yet another embodiment of the present invention, a suitable polyamide combination of an AA-BB type first polyamide (a) and an AB type second polyamide (b) is, for example, a combination in which the first polyamide (a) is selected from PA46, PA410, PA5T, PA6T / 4T, PA6T / 4T / DT / DI, PA66, PA6T, PA9T, PA10T, copolyamides or mixtures thereof, and the second polyamide (b) is selected from PA6, PA11, PA12, copolyamides or mixtures thereof. A preferred polyamide combination of the first polyamide and the second polyamide is a combination in which the first polyamide (a) is selected from PA46, PA66, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) is selected from PA6, PA11, PA12, copolyamides or mixtures thereof. A more preferred combination of the first and second polyamides is one in which the first polyamide (a) is selected from PA46, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) is selected from PA6, PA11, PA12, copolyamides or mixtures thereof. An even more preferred combination of the first and second polyamides is one in which the first polyamide (a) is selected from PA46, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) comprises or consists of PA6.

[0053] For the polyamides mentioned above, the nomenclature complies with that used in EN ISO 1874-1:2000; for example, PA6T refers to a homopolymer containing the building blocks 1,6-hexanediamine and terephthalic acid, while PA66 / 6T refers to a copolymer made from a blend of 1,6-hexanediamine, adipic acid, and terephthalic acid, and PA66, and PA6T is written as PA66 / PA6T.

[0054] Advantageously, the first polyamide (a) of AA-BB type has a concentration of amino (NH2) end groups, measured by titrating a methanolic solution of the polyamide with 0.03 N hydrochloric acid, in the range of 10 to 80 meq / kg, more preferably in the range of 15 to 75 meq / kg, even more preferably in the range of 15 to 70 meq / kg and most preferably in the range of 20 to 60 meq / kg.

[0055] Also advantageously, the second polyamide (b) of AB type has a concentration of amino (NH2) end groups in the range of 10 to 100 meq / kg, more preferably in the range of 15 to 95 meq / kg, even more preferably in the range of 15 to 90 meq / kg, and most preferably in the range of 20 to 80 meq / kg, measured by titrating a methanolic solution of the polyamide with 0.03 N hydrochloric acid.

[0056] In the context of the present invention, the first polyamide (a) of AA-BB type is present in an amount of 60 to 95% by weight, where % by weight is relative to the total weight of the thermoplastic composition. Preferably, the first polyamide (a) is present in an amount of 65 to 95% by weight, more preferably 70 to 95% by weight, where % by weight is relative to the total weight of the thermoplastic composition. More preferably, the first polyamide (a) is present in an amount of less than 95% by weight. Specifically, the first polyamide (a) is present in an amount of 60 to 90% by weight, preferably 65 to 90% by weight, even more preferably 70 to 90% by weight, where % by weight is relative to the total weight of the thermoplastic composition. More specifically, the first polyamide (a) is present in an amount of 60 to 85% by weight, preferably 65 to 85% by weight, even more preferably 70 to 85% by weight, where % by weight is relative to the total weight of the thermoplastic composition.

[0057] In the context of the present invention, the AB-type second polyamide (b) is present in a limited amount so that the overall performance of the thermoplastic composition is not affected or only slightly affected. A limited amount of the AB-type second polyamide (b) is defined as an amount within the range of 0.5 to 10 wt. %, or any subrange defined thereafter, where wt. % is based on the total weight of the thermoplastic composition. The second polyamide (b) is preferably present in an amount of 1 wt. % or more, more preferably 2 wt. % or more, even more preferably 3 wt. % or more, and most preferably 4 wt. % or more, where wt. % is based on the total weight of the thermoplastic composition. The second polyamide (b) is preferably present in an amount of 10 wt. % or less, more preferably 8 wt. % or less, even more preferably 6 wt. % or less, most preferably 5 wt. % or less, and even most preferably less than 5 wt. %, where wt. % is based on the total weight of the thermoplastic composition. That is, the second polyamide (b) is present in an amount of 4.99 wt% or less, preferably 4.95 wt% or less, more preferably 4.9 wt% or less, and most preferably 4.5 wt% or less, where wt% is based on the total weight of the thermoplastic composition.

[0058] Specifically, the second polyamide (b) is present in an amount of 0.5 to 10 wt%, preferably 0.5 to 8 wt%, more preferably 0.5 to 6 wt%, and even more preferably 0.5 to 5 wt%, where wt% is based on the total weight of the thermoplastic composition. Also specifically, the second polyamide (b) is present in an amount of 0.5 to 4.99 wt%, preferably 0.5 to 4.95 wt%, more preferably 0.5 to 4.9 wt%, and most preferably 0.5 to 4.5 wt%, where wt% is based on the total weight of the thermoplastic composition.

[0059] More specifically, the second polyamide (b) is present in an amount of 1 to 10 wt%, preferably 1 to 8 wt%, more preferably 1 to 6 wt%, and even more preferably 1 to 5 wt%, where wt% is based on the total weight of the thermoplastic composition. Also specifically, the second polyamide (b) is present in an amount of 1 to 4.99 wt%, preferably 1 to 4.95 wt%, more preferably 1 to 4.9 wt%, and most preferably 1 to 4.5 wt%, where wt% is based on the total weight of the thermoplastic composition.

[0060] Even more specifically, the second polyamide (b) is present in an amount of 2 to 10 wt%, preferably 2 to 8 wt%, more preferably 2 to 6 wt%, and even more preferably 2 to 5 wt%, where wt% is based on the total weight of the thermoplastic composition. Also specifically, the second polyamide (b) is present in an amount of 2 to 4.99 wt%, preferably 2 to 4.95 wt%, more preferably 2 to 4.9 wt%, and most preferably 2 to 4.5 wt%, where wt% is based on the total weight of the thermoplastic composition.

[0061] Even more specifically, the second polyamide (b) is present in an amount of 4 to 10 wt%, preferably 4 to 8 wt%, more preferably 4 to 6 wt%, and even more preferably 4 to 5 wt%, where wt% is based on the total weight of the thermoplastic composition. Also specifically, the second polyamide (b) is present in an amount of 4 to 4.99 wt%, preferably 4 to 4.95 wt%, more preferably 4 to 4.9 wt%, and most preferably 4 to 4.5 wt%, where wt% is based on the total weight of the thermoplastic composition.

[0062] The thermoplastic composition of the present invention further comprises a functionally modified polyolefin, i.e., a polyolefin modified (grafted) with a functional group capable of reacting with the end groups and / or backbone amide groups of the polyamide.

[0063] Suitable polyolefin polymers for the thermoplastic compositions of the present invention are homopolymers and copolymers of one or more olefin polymers that may be grafted with functional groups.

[0064] Examples of suitable polyolefin polymers are ethylene polymers, propylene polymers, and styrene-butadiene-styrene block copolymers, or hydrogenated forms thereof.

[0065] Examples of suitable ethylene polymers include all thermoplastic homopolymers of ethylene and copolymers of ethylene with one or more α-olefins containing 3 to 10 carbon atoms as comonomers, specifically propylene, isobutene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene, which can be prepared using known catalysts, such as Ziegler-Natta, Phillips, and metallocene catalysts. The amount of comonomer is typically in the range of 0 to 50% by weight, preferably 5 to 35% by weight. Such ethylene polymers are known, for example, as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and linear very low-density polyethylene (VL(L)DPE). Suitable polyethylene polymers have a viscosity of 800 to 970 kg / m 3 It has a density of

[0066] Examples of suitable propylene polymers are homopolymers of propylene and copolymers of propylene and ethylene, the ethylene moieties amounting to a total of up to 30% by weight, preferably up to 25% by weight.

[0067] Suitable functional groups are those that can be grafted onto at least one of the suitable polyolefin polymers described above. Examples of such functional groups include carboxylic acid groups, metal carboxylate groups, acid anhydride groups, ester groups, epoxy groups, oxazoline groups, amino groups, isocyanate groups, and mixtures thereof. Preferably, the functional group is selected from epoxy groups, acid anhydride groups, and mixtures thereof. More preferably, the functional group is an acid anhydride group.

[0068] Therefore, the functionally modified polyolefin is advantageously selected from the group consisting of dicarboxylic acid anhydride-modified polyolefins, epoxy-modified polyolefins, and mixtures thereof. Preferably, the functionally modified polyolefin is a maleic anhydride (MAH)-grafted polyolefin. More preferably, the functionally modified polyolefin is selected from maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene copolymer, and maleic anhydride-modified ethylene copolymer.

[0069] Advantageously, the functionally modified polyolefin has a modulus of 800 to 970 kg / m as measured according to ISO standard ISO 1183. 3 range, preferably 820 to 970 kg / m 3 in the range of 850 to 970 kg / m 3 in the range of 850 to 950 kg / m 3 range, more preferably 860 to 950 kg / m 3 range, more preferably 860 to 920 kg / m 3 and even more preferably in the range of 860 to 900 kg / m 3 It has a density in the range of

[0070] Advantageously, the melt flow rate (MFR; 230°C, 2.16 kg load) of the functionally modified polyolefin is in the range of 0.5 to 25 g / 10 min, preferably in the range of 0.5 to 15 g / 10 min, more preferably in the range of 0.5 to 10 g / 10 min, more preferably in the range of 0.5 to 8 g / 10 min, even more preferably in the range of 1 to 8 g / 10 min, and most preferably in the range of 1.5 to 7.5 g / 10 min, as measured according to ASTM standard D1238.

[0071] Also advantageously, the content of functional groups in the modified polyolefin is in the range of 0.05 to 3.0 wt%, preferably in the range of 0.05 to 2.5 wt%, preferably in the range of 0.1 to 2.5 wt%, preferably in the range of 0.2 to 2.5 wt%, more preferably in the range of 0.3 to 2.5 wt%, more preferably in the range of 0.3 to 2.0 wt%, even more preferably in the range of 0.4 to 2.0 wt%, even more preferably in the range of 0.4 to 1.5 wt%, even more preferably in the range of 0.4 to 1.2 wt%, and most preferably in the range of 0.5 to 1.0 wt%, where wt% is relative to the total weight of the functional group modified polyolefin.

[0072] Specifically, the maleic anhydride (MAH) content in the modified polyolefin is in the range of 0.05 to 3.0 wt%, preferably 0.05 to 2.5 wt%, preferably 0.1 to 2.5 wt%, preferably 0.2 to 2.5 wt%, more preferably 0.3 to 2.5 wt%, more preferably 0.3 to 2.0 wt%, even more preferably 0.4 to 2.0 wt%, even more preferably 0.4 to 1.5 wt%, even more preferably 0.4 to 1.2 wt%, and most preferably 0.5 to 1.0 wt%, where wt% is based on the total weight of the functional group-modified polyolefin. The MAH content is measured by infrared spectroscopy as described in the "Test Methods" section of the Examples.

[0073] The modified polyolefins can be prepared according to methods known per se for this purpose, for example, as described in U.S. Patent Nos. 3,236,917, 5,194,509, and 4,950,541. In addition, the modified polyolefins are also commercially available under various trade names, such as Fusabond®, Exxelor™, Tafmer®, and Paraloid™.

[0074] In the thermoplastic composition of the present invention, the functionally modified polyolefin (c) is advantageously present in an amount of 0.5 to 35 wt%, preferably 1 to 35 wt%, more preferably 5 to 35 wt%, even more preferably 8 to 35 wt%, and most preferably 10 to 35 wt%, where wt% is based on the total weight of the thermoplastic composition. Also advantageously, the functionally modified polyolefin (c) is present in an amount of 0.5 to 30 wt%, preferably 1 to 30 wt%, more preferably 5 to 30 wt%, even more preferably 8 to 30 wt%, and most preferably 10 to 30 wt%, where wt% is based on the total weight of the thermoplastic composition. Also advantageously, the functionally modified polyolefin (c) is present in an amount of 0.5 to 25 wt%, preferably 1 to 25 wt%, more preferably 5 to 25 wt%, even more preferably 8 to 25 wt%, and most preferably 10 to 25 wt%, where wt% is based on the total weight of the thermoplastic composition. Advantageously, the functionally modified polyolefin (c) is present in an amount of 0.5 to 20 wt%, preferably 1 to 20 wt%, more preferably 5 to 20 wt%, even more preferably 8 to 20 wt%, and most preferably 10 to 20 wt%, wherein wt% is relative to the total weight of the thermoplastic composition. Advantageously, the functionally modified polyolefin (c) is present in an amount of 0.5 to 19 wt%, preferably 1 to 19 wt%, more preferably 5 to 19 wt%, even more preferably 8 to 19 wt%, and most preferably 10 to 19 wt%, wherein wt% is relative to the total weight of the thermoplastic composition.

[0075] In a further embodiment of the present invention, the thermoplastic composition of the present invention may comprise at least one other component (d). For example, the other component may be: - polymers other than polyamides (a), polyamides (b), and functionally modified polyolefins (c); - inorganic nucleating agents, - inorganic fillers and / or fiber reinforcing agents, and - auxiliary additives, or a mixture thereof.

[0076] Regarding polymers other than polyamide (a), polyamide (b), and functionally modified polyolefin (c), in principle, any thermoplastic or thermosetting polymer can be used, as long as they are used in limited amounts so that the overall performance of the thermoplastic composition is not affected or only slightly affected. For example, the polymer may be unmodified polyolefin. Preferably, the amount is limited to, for example, 0.01 to 20 wt. %, where wt. % is based on the total weight of the thermoplastic composition. In practice, if any polymer is used at all, the amount is limited to, for example, 0.01 to 15 wt. %, or even 0.01 to 10 wt. %, where wt. % is based on the total weight of the thermoplastic composition.

[0077] Suitable inorganic nucleating agents may be selected from microtalc and carbon black. The inorganic agent may be present in an amount ranging from approximately 0.01 to 5% by weight, where the weight percent is based on the total weight of the thermoplastic composition.

[0078] Regarding the inorganic filler and / or fiber reinforcement, any inorganic material that improves mechanical properties such as tensile strength and tensile modulus can be used. Many of these materials can have a negative effect on the wear resistance of the plastic material, so their amount, if used at all, should preferably be limited. Examples of fiber reinforcement are glass fiber and carbon fiber. Of these, carbon fiber is preferred because it can sometimes improve low friction.

[0079] If present, suitably the total amount of inorganic fillers and / or fibrous reinforcing agents in the composition is, for example, in the range of 0.01 to 20 wt%, where wt% is based on the total weight of the thermoplastic composition. Preferably, the amount is in the range of 0.01 to 15 wt%, or more specifically 0.01 to 10 wt%, where wt% is based on the total weight of the thermoplastic composition.

[0080] In a preferred embodiment, the inorganic filler is a granular or particulate solid inorganic lubricant. The solid inorganic lubricant may include a material selected from the group consisting of molybdenum disulfide, natural or synthetic graphite, boron nitride, and silane nitride, and any mixture thereof. By using the term "natural or synthetic graphite" herein, it is understood that this graphite is different from the graphite platelets used as the primary solid lubricant of the present invention.

[0081] When present, solid inorganic lubricant particles may be present in an amount ranging, for example, from 0.01 to 10% by weight, although larger amounts may be used. Preferably, if such solid lubricants are used at all, the amount is limited to the range of 0.01 to 7.5% by weight, or even 0.01 to 5% by weight, where the weight percent is based on the total weight of the thermoplastic composition.

[0082] The composition may also contain auxiliary additives. Examples of auxiliary additives include mold release agents, pigments, and stabilizers such as thermal stabilizers, oxidative stabilizers, UV stabilizers, and chemical stabilizers. When present, such auxiliary additives are typically used in limited amounts, for example, in the range of 0.01 to 10 wt. %. Preferably, if used at all, the amount is limited to the range of 0.01 to 7.5 wt. %, 0.01 to 5 wt. %, or even 0.01 to 2.5 wt. %, where wt. % is based on the total weight of the thermoplastic composition.

[0083] In the context of the present invention, the other component (d) is preferably not polytetrafluoroethylene, molybdenum disulfide, or graphite.

[0084] Thus, in one embodiment, the thermoplastic composition for use in the sliding element comprises: - 60 to 95% by weight of a first polyamide (a) which is a polyamide of the AA-BB type, - 0.5 to 10% by weight, preferably 1 to 10% by weight, more preferably 2 to 10% by weight, even more preferably 2 to 8% by weight, even more preferably 2 to 6% by weight, even more preferably 4 to 6% by weight, even more preferably 4 to 5% by weight, most preferably 4 to 4.95% by weight of a second polyamide (b) which is an AB type polyamide, and - 0.5 to 35% by weight, preferably 1 to 35% by weight, more preferably 1 to 30% by weight, even more preferably 1 to 25% by weight, even more preferably 1 to 20% by weight, most preferably 1 to 19% by weight of functionally modified polyolefin (c), Here, the weight percent is based on the total weight of the thermoplastic composition.

[0085] The composition of the above embodiment comprises: - It may further comprise 0 to 30% by weight of at least one other component (d), where the weight % is relative to the total weight of the thermoplastic composition.

[0086] Alternatively, the composition may comprise: It may further comprise 0.01 to 10% by weight of auxiliary additives, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0087] Alternatively, the composition may comprise: 0.01 to 10% by weight of auxiliary additives, and It may further comprise 0.01 to 20% by weight of inorganic fillers and / or fibrous reinforcing agents, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0088] In a further embodiment, the thermoplastic composition for use in the sliding element comprises: - 70 to 95% by weight of a first polyamide (a) which is a polyamide of the AA-BB type, - 0.5 to 10% by weight, preferably 1 to 10% by weight, more preferably 2 to 10% by weight, even more preferably 2 to 8% by weight, even more preferably 2 to 6% by weight, even more preferably 4 to 6% by weight, even more preferably 4 to 5% by weight, most preferably 4 to 4.95% by weight of a second polyamide (b) which is an AB type polyamide, and - 0.5 to 25 wt. %, preferably 1 to 25 wt. %, more preferably 1 to 20 wt. %, most preferably 1 to 19 wt. % of functionally modified polyolefin (c), Here, the weight percent is based on the total weight of the thermoplastic composition.

[0089] The composition of the above further embodiment further comprises: - 0 to 20% by weight of at least one other component (d), where the weight percentages are relative to the total weight of the thermoplastic composition.

[0090] Alternatively, the composition may further comprise - It may contain 0.01 to 10% by weight of auxiliary additives, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0091] Alternatively, the composition may further comprise - 0.01 to 5% by weight of auxiliary additives, and - may contain 0.01 to 15% by weight of inorganic fillers and / or fibrous reinforcing agents, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0092] In yet another further embodiment, the thermoplastic composition for use in a sliding element comprises: - 70 to 90% by weight of a first polyamide (a) which is a polyamide of the AA-BB type, - 1 to 10% by weight, preferably 2 to 10% by weight, more preferably 2 to 8% by weight, even more preferably 2 to 6% by weight, even more preferably 4 to 6% by weight, even more preferably 4 to 5% by weight, most preferably 4 to 4.95% by weight of a second polyamide (b) which is an AB type polyamide, and - 0.5 to 25% by weight, preferably 1 to 25% by weight, more preferably 5 to 25% by weight, even more preferably 5 to 20% by weight, most preferably 5 to 19% by weight of functionally modified polyolefin (c), Here, the weight percent is based on the total weight of the thermoplastic composition.

[0093] The composition of the above further embodiment further comprises: - 0 to 20% by weight of at least one other component (d), where the weight percentages are relative to the total weight of the thermoplastic composition.

[0094] Alternatively, the composition may further comprise - It may contain 0.01 to 10% by weight of auxiliary additives, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0095] Alternatively, the composition may further comprise - 0.01 to 5% by weight of auxiliary additives, and - may contain 0.01 to 15% by weight of inorganic fillers and / or fibrous reinforcing agents, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0096] In yet another further embodiment, the thermoplastic composition for use in a sliding element comprises: - 70 to 85% by weight of a first polyamide (a) which is a polyamide of the AA-BB type, - 2 to 10% by weight, more preferably 2 to 8% by weight, even more preferably 2 to 6% by weight, even more preferably 4 to 6% by weight, even more preferably 4 to 5% by weight, most preferably 4 to 4.95% by weight of a second polyamide (b) which is an AB type polyamide, and - 0.5 to 25% by weight, preferably 5 to 25% by weight, even more preferably 5 to 20% by weight, even more preferably 8 to 20% by weight, even more preferably 10 to 20% by weight, most preferably 10 to 19% by weight of functionally modified polyolefin (c), Here, the weight percent is based on the total weight of the thermoplastic composition.

[0097] The composition of the above further embodiment further comprises: - 0 to 15% by weight of at least one other component (d), where the weight percentages are relative to the total weight of the thermoplastic composition.

[0098] Alternatively, the composition may further comprise - It may contain 0.01 to 10% by weight of auxiliary additives, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0099] Alternatively, the composition may further comprise - 0.01 to 5% by weight of auxiliary additives, and - may contain 0.01 to 10% by weight of inorganic fillers and / or fibrous reinforcing agents, where the weight percentages are relative to the total weight of the thermoplastic composition.

[0100] With respect to the above embodiment, further embodiments regarding the selection of polyamide (a), polyamide (b), functionally modified polyolefin (c), and at least one other component (d) are as detailed hereinabove. Specifically, in one embodiment, the first polyamide (a) is selected from PA46, PA66, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) is selected from PA6, PA11, PA12, copolyamides or mixtures thereof. More preferably, the first polyamide (a) is selected from PA46, PA66, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) comprises PA6. Even more preferably, the first polyamide (a) is selected from PA46, PA66, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) consists of PA6. Even more preferably, the first polyamide (a) is selected from PA46, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) consists of PA6.

[0101] Surprisingly, it has been found that the thermoplastic compositions of the present invention exhibit very good processability and impart excellent sliding properties to molded parts made therefrom in combination with advantageous wear resistance and mechanical properties (such as impact resistance, bending stiffness, and ductility).

[0102] The manufacture of molded parts can be carried out using standard methods known to those skilled in the art, such as injection molding, as illustrated in the examples.

[0103] The above properties of workability, sliding resistance, abrasion resistance, impact resistance, bending rigidity, and ductility were evaluated by the methods described in the "Test Methods" section of the Examples.

[0104] Specifically, the processability of the thermoplastic compositions of the present invention, evaluated during compounding or injection molding, was found to be significantly improved compared to the processability of corresponding compositions that did not contain the second polyamide (b) of the AB type (i.e., compositions that simply contained the first polyamide (a) of the AA-BB type and the functionally modified polyolefin (c)).

[0105] In other words, it has been found that the addition of a limited amount of a second polyamide (b) of the AB type to a composition comprising a first polyamide (a) of the AA-BB type and a functionally modified polyolefin (c) results in significantly improved processability.

[0106] When the processability of the thermoplastic compositions of the present invention was evaluated by torque (%) as measured in the examples, it was found that increasing the amount of AB-type second polyamide (b) decreased the torque (%). That is, increasing the amount of AB-type second polyamide (b) increased the processability of the thermoplastic compositions of the present invention. This torque (%) was about 1%, preferably about 2%, more preferably about 3%, even more preferably about 4%, even more preferably about 5%, even more preferably about 6%, and most preferably about 8% lower than the torque (%) of the corresponding composition not containing AB-type second polyamide (b).

[0107] The results showed that the degree of degradation of the thermoplastic composition of the present invention was significantly reduced compared to the degree of degradation of the corresponding composition not containing the second polyamide (b) of the AB type.

[0108] When the degree of degradation of the thermoplastic compositions of the present invention was evaluated by viscosity number (ml / g) as measured in the examples, it was found that the viscosity number (ml / g) increased with increasing amount of AB type second polyamide (b). That is, the degree of degradation of the thermoplastic compositions of the present invention decreased with increasing amount of AB type second polyamide (b). The viscosity number (ml / g) of the thermoplastic compositions of the present invention was about 1%, preferably about 2%, more preferably about 3%, even more preferably about 5%, even more preferably about 6%, even more preferably about 8%, and most preferably about 10% higher than the viscosity number (ml / g) of the corresponding composition not containing AB type second polyamide (b).

[0109] As a further result, it has been found that molded parts comprising the thermoplastic composition of the present invention have a good, or even very good, surface appearance.

[0110] The sliding properties of molded parts containing the thermoplastic compositions of the present invention were evaluated by measuring the coefficient of friction (CoF) of the parts, as described in the Examples. It was found that the coefficient of friction evaluated under lubricated (i.e., oil) conditions at high temperatures (i.e., in the range of 60°C to 150°C) on molded parts containing the thermoplastic compositions of the present invention was not only significantly reduced compared to the coefficient of friction of molded parts containing a reference composition, but was also generally lower than the coefficient of friction of molded parts containing corresponding materials containing other friction-reducing additives (commonly referred to as solid lubricants). For example, it was found that the performance of molded parts containing the thermoplastic compositions of the present invention was higher than the performance of molded parts containing compositions containing molybdenum sulfide, graphite, or PTFE.

[0111] The "reference composition" is defined as a composition containing a first polyamide (a) of AA-BB type but not containing a second polyamide (b) of AB type and a functionally modified polyolefin (c). In other words, the "reference composition" is defined as a composition of the present invention that does not contain a second polyamide (b) of AB type and a functionally modified polyolefin (c).

[0112] In the context of this invention, for example, when the coefficient of friction is measured using the chain-on-guide test described in the "Test Methods" section of the Examples, an improvement in friction is defined as a reduction in the coefficient of friction of at least about 5%, where the percent reduction is relative to the coefficient of friction of a molded part containing a reference composition. This reduction of about 5% is a significant improvement for applications such as chain tensioners.

[0113] In certain cases where the coefficient of friction is measured using the ball-on-pyramid test described in the "Test Methods" section of the Examples at a sliding speed of 0.01 m / s, the reduction in the coefficient of friction is at least about 10%, at least about 15%, preferably at least about 20%, at least about 25%, at least about 30%, more preferably at least about 35%, at least about 40%, even more preferably at least about 45%, and most preferably at least about 50%, where the percent reduction is relative to the coefficient of friction of a molded part containing the reference composition. At a sliding speed of 0.05 m / s, the reduction in the coefficient of friction is at least about 20%, preferably at least about 30%, more preferably at least about 40%, even more preferably at least about 50%, even more preferably at least about 55%, and most preferably at least about 60%, where the percent reduction is relative to the coefficient of friction of a molded part containing the reference composition. At a sliding speed of 0.1 m / s, the reduction in the coefficient of friction is at least about 25%, preferably at least about 30%, more preferably at least about 40%, more preferably at least about 45%, even more preferably at least about 50%, even more preferably at least about 60%, and most preferably at least about 70%, where the percent reduction is relative to the coefficient of friction of a molded part containing a reference composition. Typically, the coefficient of friction of molded parts containing the thermoplastic compositions of the present invention, determined at a sliding speed of 0.1 m / s, is in the range of 0.005 to 0.1, preferably 0.005 to 0.09, 0.005 to 0.07, more preferably 0.005 to 0.06, 0.005 to 0.05, and even more preferably 0.005 to 0.04.

[0114] Surprisingly, it was also found that the sliding properties of molded parts containing the thermoplastic compositions of the present invention were within the same range as those of molded parts containing corresponding compositions that did not contain the AB-type second polyamide (b), as shown by the measured CoF of the above compositions in the Examples. In other words, the addition of the AB-type second polyamide (b) did not adversely affect the sliding performance of the resulting molded parts. As a result, molded parts containing the thermoplastic compositions of the present invention maintained excellent sliding properties, i.e., similar to those of molded parts containing corresponding compositions that did not contain the AB-type second polyamide (b).

[0115] In addition to excellent sliding properties, it has surprisingly been found that molded parts comprising the thermoplastic compositions of the present invention exhibit advantageous wear resistance.

[0116] Surprisingly, it was also found that the abrasion resistance of molded parts comprising the thermoplastic composition of the present invention was either similar or improved compared to the abrasion resistance of molded parts comprising a corresponding composition that did not contain an AB type second polyamide (b), as shown in the evaluation of the abrasion resistance of the above compositions in the examples. Furthermore, it was found that molding compositions comprising a corresponding thermoplastic composition that contained an AB type second polyamide (b) in an amount of more than 10 wt. % (where wt. % is relative to the total weight of the thermoplastic composition) showed reduced abrasion resistance when compared to molding compositions comprising the thermoplastic composition of the present invention.

[0117] Besides excellent sliding properties and advantageous wear resistance, it has surprisingly been found that molded parts comprising the thermoplastic compositions of the present invention exhibit advantageous mechanical properties of impact resistance, bending stiffness, and ductility.

[0118] It has been found that the thermoplastic compositions of the present invention exhibit advantageous mechanical properties compared to the mechanical properties of corresponding compositions not comprising the second polyamide (b) of the AB type.

[0119] As shown in the examples, molded parts comprising the thermoplastic composition of the present invention maintained good impact resistance or even showed significantly improved impact resistance compared to corresponding compositions not comprising the second polyamide (b) of the AB type.

[0120] Additionally, the flexural rigidity of molded parts containing the thermoplastic compositions of the present invention was either similar to or significantly improved compared to the flexural rigidity of molded parts containing corresponding compositions that did not contain the AB-type second polyamide (b), as shown by the tensile modulus measurements of the above compositions in the Examples. Specifically, the flexural rigidity of molded parts made from the thermoplastic compositions of the present invention containing PA46 was significantly improved compared to the flexural rigidity of molded parts containing corresponding compositions that did not contain the AB-type second polyamide (b).

[0121] Furthermore, as shown in the examples, molded parts comprising the thermoplastic composition of the present invention maintained good yield strength at high temperatures (e.g., 120°C) compared to corresponding compositions that did not contain the AB-type second polyamide (b). However, compared to molding compositions comprising the thermoplastic composition of the present invention, molding compositions comprising the corresponding thermoplastic composition containing the AB-type second polyamide (b) in an amount of more than 10 wt. % (where wt. % is relative to the total weight of the thermoplastic composition) showed a significant reduction in yield strength, i.e., a loss of yield strength of 10% or more.

[0122] Furthermore, the ductility of molded parts comprising the thermoplastic compositions of the present invention, as shown by the measurements of the elongation at break of the above compositions in the examples, was either similar or significantly improved compared to the ductility of molded parts comprising corresponding compositions that did not contain the second polyamide (b) of the AB type.

[0123] Thus, the addition of a limited amount of a second polyamide (b) to a composition comprising a first polyamide (a) of the AA-BB type and a functionally modified polyolefin (c) results in a composition that exhibits significantly improved processability and imparts excellent sliding properties combined with advantageous wear resistance and mechanical properties to molded parts made therefrom.

[0124] The above advantages are particularly applicable in industrial applications such as plastic elements that slide relative to each other.

[0125] Thus, one aspect of the present invention relates to a molded part that is for use in a sliding element and that comprises the thermoplastic composition of the present invention, or any preferred embodiment thereof as described herein above.

[0126] A further aspect of the present invention relates to a sliding element comprising the thermoplastic composition of the present invention, or any preferred embodiment thereof as described herein above.

[0127] In one embodiment, the sliding element is for use in a lubricated sliding system.

[0128] In another embodiment, the sliding element is for use in a chain transmission, the sliding element including a sliding portion for sliding engagement with a chain, the sliding portion being made primarily from the thermoplastic composition of the present invention.

[0129] The sliding element typically has a body intended to support and optionally strengthen the sliding contact part and to provide bending and torsional rigidity to the entire sliding element. The body also generally has a part by means of which the body can be fixed to a base. Said fixed part may for example comprise a bushing by which the body can be rotatably mounted on a metal pin inserted into the bushing (this pin being fixed to the base).

[0130] The sliding contact portion and the main body may be made from the same material, but it is preferable that they are made from different materials because the sliding contact portion has low friction characteristics as a main requirement, while the main body must provide mechanical strength, bending rigidity, and torsional rigidity, and these properties are difficult to combine without compromising one property for the other.

[0131] Therefore, in a further embodiment, the sliding element comprises a body supporting the sliding contact, wherein the body is made of a material different from the thermoplastic composition. For example, the body is made of a plastic material or a metal (such as aluminum), preferably a plastic material, more preferably a fiber-reinforced plastic material. For mechanical properties, it is advantageous to design the sliding element so that the body consists of a fiber-reinforced thermoplastic material and the surface layer consists of a non-reinforced thermoplastic material.

[0132] If the sliding contact portion and the body are made from different materials, the sliding contact portion and the body can be combined into an integral sliding element by known means.

[0133] For example, the sliding contact portion may comprise a surface layer on the body. The sliding element may be overmolded onto the body and mechanically interlocked with the body. Preferably, the surface layer has a thickness of 5 μm to 5 mm, but the surface layer may also be thicker than 5 mm or thinner than 5 μm.

[0134] If the body is made from a second plastic material, some or all of the joint between the sliding portion and the reinforcing body may be joined by melting, for example, vibration welding. In another alternative embodiment, the thermoplastic composition of the sliding portion and the second plastic material are integrally molded together by a two-component injection process (also known as 2K molding or two-component molding), so that they are fixed together when they harden. The material that forms the body is injected into a mold first, followed immediately by the thermoplastic composition that forms the coating or surface layer.

[0135] Preferably, when the main body is made from the second plastic material, the sliding contact portion is integrally molded with the main body.

[0136] In an alternative embodiment usable for chain guides and chain tensioners, the sliding contact portion may be included in a sliding blade that is mechanically interlocked with the main body. Interlocking with the main body can be achieved, for example, by inserting a sliding blade having an end portion into a groove formed at each end of the main body. The sliding blade may consist solely of the thermoplastic composition from which the sliding contact portion is made, or may include a base made of a second material different from the thermoplastic composition, while the sliding contact portion constitutes a surface layer on the base. When the sliding contact portion and the base are made of different materials, they may be combined into an integrated sliding blade by the same method as described above for the sliding contact portion and the main body.

[0137] If the base is made of a different material, it is preferably made of a plastic material, more preferably a fiber-reinforced plastic material. If the base is made of a second plastic material, the sliding contact part is preferably integrally molded with the base.

[0138] The sliding element of the present invention is preferably lubricated (in oil) and is intended for use in sliding systems, more particularly timing chain drive systems, such as powertrain drive systems including engines, transmission differentials, and drive shaft systems. In particular, the engine is an internal combustion engine equipped with a lubricated chain drive system.

[0139] In such systems, the sliding elements are in sliding contact with the lubricated chain during engine operation, specifically the chain guide and the chain tensioner arm.

[0140] The sliding element of the present invention can also be part of a gear or a bearing.

[0141] The present invention also relates to a chain guide and a chain tensioner, respectively, comprising a sliding element including the surface layer or bearing of the present invention or including the surface layer in a lubricated sliding system, preferably a powertrain drive system including an engine, a transmission differential, and a drive shaft system.

[0142] The present invention also relates to a powertrain drive system comprising an engine, a transmission and differential, and plastic components including a drive shaft system, a drive chain, and a sliding element in contact with the lubricated drive chain. Preferably, the sliding element in the powertrain drive system is the sliding element of the present invention or any preferred embodiment thereof, as described in more detail herein above.

[0143] A further aspect of the present invention relates to an engine comprising a first element including a portion in sliding engagement with a second element. The portion in sliding engagement with the second element is referred to herein as the sliding portion. Herein, the first element is a sliding element, in which at least the sliding portion is made, or at least primarily made, of the inventive thermoplastic composition or any preferred embodiment thereof described herein above. Preferably, the first element, i.e., the sliding element, is part of a chain guide, a chain tensioner, a gear, or a bearing.

[0144] Yet a further aspect of the present invention relates to a chain transmission comprising a chain and a sliding element comprising a sliding part in sliding engagement with the chain, wherein the sliding part is made, or at least mainly made, of the inventive thermoplastic composition described herein above or any preferred embodiment thereof. The sliding element in the chain transmission is preferably a chain guide or a chain tensioner. The chain transmission is preferably a chain-driven timing system. In a preferred embodiment, the chain transmission is advantageously an (oil) lubricated sliding system, although it may also be a non-lubricated sliding system.

[0145] Reference herein to a patent document or other material offered as prior art should not be construed as an admission that the document or material was publicly known or that the information contained therein was part of the general common knowledge as of the priority date of any claim.

[0146] The present invention is further illustrated by the following examples and comparative experiments. [Example]

[0147] [material] PA46 Polyamide 46 (DSM, Netherlands), VN = 205 ml / g, Tm = 290 °C, NH2 end group content = 24 meq / kg PA66 Polyamide 66 (DSM, Netherlands), VN = 168 ml / g, Tm = 260 °C, NH2 end group content = 30 meq / kg PPA Polyamide 6T / 4T / 6I (54 / 24 / 22 mol / mol / mol) (DSM, Netherlands), VN = 125 ml / g, Tm = 322 °C, NH2 end group content = 40 meq / kg PA6 Polyamide 6 (DSM, Netherlands), VN = 115 ml / g, Tm = 220 °C, NH2 end group content = 54 meq / kg MAH-EP Exxelor™ VA1801 (ExxonMobil Chemical): Maleic anhydride (MAH) modified ethylene propylene copolymer (EP), MAH content = 0.62 wt %, MFR (230°C, 2.16 kg load) = 2 g / 10 min, density = 880 kg / m 3 Stanyl® HGR2 Polyamide 46 + PTFE (DSM, Netherlands) Leona™ 1542 Polyamide 66 + PTFE (Asahi Kasei Corporation, Japan)

[0148] [Preparation (blending) of thermoplastic composition] Thermoplastic compositions were prepared from PA46 and various fillers in a Berstorff ZE25 / 48UTX co-rotating twin-screw extruder. The extruder temperature settings were such that the melt temperature at the extruder outlet was typically 330°C. Compositions containing PA46 are listed in Tables 1 and 3.

[0149] Thermoplastic compositions were prepared from PA66 and various fillers in a Berstorff ZE25 / 48UTX co-rotating twin-screw extruder. The extruder temperature settings were such that the melt temperature at the extruder outlet was typically 310°C. Compositions containing PA66 are listed in Tables 1 and 4.

[0150] Thermoplastic compositions were prepared from PPA and various fillers in a Berstorff ZE25 / 48UTX co-rotating twin-screw extruder. The extruder temperature settings were such that the melt temperature at the extruder outlet was typically 350° C. Compositions containing PPA are listed in Table 1.

[0151] Preparation of injection molded parts The PA46-, PA66-, and PPA-based thermoplastic compositions reported in Table 1 and used to prepare the injection-molded test specimens were pre-dried by applying the following conditions: the compositions were heated to 105°C for the PA46- and PPA-based compositions and 80°C for the PA66-based compositions under a vacuum of 0.02 MPa, and these temperatures and pressures were maintained for 24 hours while a nitrogen flow was applied. The pre-dried compositions were injection-molded on an Arburg A150 (40 mm) injection molding machine using a mold with a cavity to provide test specimens (e.g., strips, bars, and plates) used for the characterization tests described below. The temperature of the cylinder wall was selected so that the melt temperature was 20°C higher than the melt temperature of the polyamide for the PA46- and PA66-based compositions and 10°C higher for the PPA-based compositions. The mold temperature was set to 120°C for the PA46- and PPA-based compositions and 80°C for the PA66-based composition. The parts thus obtained were cooled and stored under dry conditions at room temperature before being used in the characterization tests described below.

[0152] [Test method] Melting temperature (Tm) The melting temperature (°C) of polyamides was measured on pre-dried samples under N2 atmosphere at a heating / cooling rate of 10°C / min according to the DSC method in accordance with ISO-11357-1 / 3, 2011. Herein, Tm was calculated from the peak value of the highest melting peak in the second heating cycle.

[0153] [Amino (NH2) end group content] The amino end group content (meq / kg) in the polyamide was determined potentiometrically by titrating a methanol solution of the polyamide with 0.03N hydrochloric acid.

[0154] Melt Flow Rate (MFR) The melt flow rates of the MAH-modified polyolefins were determined at 230° C. and 2.16 kg load by a method according to ASTM standard D1238.

[0155] [Maleic anhydride (MAH) content] MAH-modified polyolefin membranes were prepared by melt-pressing, and FT-IR spectra for the membranes were recorded using a Perkin Elmer Spectrum One FT-IR spectrometer. Peak height measurements were performed on the absorbance spectra. Corrections for membrane thickness differences were made at 722 cm. -1 This was done by normalizing the spectrum using the vibrational signal of the MAH-modified polyolefin, which is the peak at 722 cm -1 For peak height determination in (H1), the baseline was set at 2000 cm -1 and 640cm -1 Draw between 1862cm -1 For the determination of peak height in (H2), the baseline was set at 1910 cm -1 and 1640cm -1 The weight percent of MAH on the sample is calculated using the following formula: MAH (wt%) = 4.2176 * (H2 / H1).

[0156] [density] Density of modified polyolefin (kg / m 3 ) was measured by a method according to ISO standard ISO1183.

[0157] [Workability] The processability of the thermoplastic composition during compounding was evaluated by measuring the torque (%) while preparing it in a ZE25 / 48UTX Berstorff extruder operating at 300 rpm and a throughput of 20 kg / h. The processability of the thermoplastic compositions during injection molding was determined based on a visual evaluation of the surface appearance of the resulting molded parts.

[0158] [Viscosity number (VN)] The viscosity number (ml / g) of the compounded polyamide or thermoplastic compositions was determined at 25°C by a method according to ISO 307 (0.5% by weight in 96% by weight sulfuric acid for PPA and PA66, and 0.5% by weight in 90% by weight formic acid for PA6 and PA46).

[0159] Tensile modulus The tensile modulus (MPa) of the molded test specimens was measured in a tensile test according to ISO 527 at 50 mm / min and 23°C.

[0160] [Yield strength] The tensile modulus (MPa) of the molded test specimens was measured in a tensile test according to ISO 527 at 50 mm / min and 120°C.

[0161] [Elongation at break] The elongation at break (%) of the molded test specimens was measured in a tensile test according to ISO 527 at 23°C or 120°C and 50 mm / min.

[0162] [Impact resistance (i.e., impact strength)] Impact strength of molded test specimen (kJ / m 2 ) was determined in a Charpy notched impact strength test at 23°C according to ISO 179 / 1eU and in an Izod notched impact strength test at -20°C according to ISO 180.

[0163] [Measurement of the coefficient of friction (CoF) in chain-on-guide tests] A chain (Schaeffler I6G2, 84 rings, surface roughness RA approximately 0.1 μm to 0.2 μm) was placed between two identical sprockets (B1) and (B2) (Schaeffler, z=24), and the sprockets were prestressed with a force of 670 N ± 10 N, as shown in Figure 1. A formed strip test specimen with dimensions of 30 mm (width) × 125 mm (length) × 2 mm (thickness) was mounted on a support (C) with a curvature radius of 110 mm. The formed strip test specimen (D) and support (C) were placed in a 100 N equivalent bearing force (F S The system was placed in a compartment and heated to the test temperature (120°C) by spraying commercial engine oil (Castrol Edge 5W30 FST) at a flow rate of 2 rpm and 2 bar onto the chain at positions E1 and E2. The system was allowed to equilibrate for 1 hour. The bearing force (FS The chain was run on the plastic guide at a constant speed for 1 hour by increasing the friction force (F) to 175 N ± 5 N and driving sprocket B1 (sprocket speed: 1000 rpm, chain sliding speed: 2.55 m / s). After this break-in phase, the actual friction measurements began by increasing the sprocket speed stepwise from 500 rpm to 5000 rpm. At each sprocket speed, the system was first allowed to equilibrate for 5 seconds, after which the drag force (F D ) and bearing capacity (F S ) was recorded for 5 seconds. The average over these 5 seconds was used to calculate CoF. The step increase between two speed levels took 3 seconds. CoF is calculated by the ratio F D / F S Determined from the formula, F D is the resistance force and F S is the bearing capacity.

[0164] [Measurement of the coefficient of friction (CoF) in the ball-on-pyramid test] The setup, commercially available as an Anton-Paar Tribo-cell T-BTP, was mounted on an Anton-Paar MCR 501 rheometer. Three identical molded test specimens, A1, A2, and A3, measuring 6 mm (width) x 15 mm (length) x 2 mm (thickness), were placed under a 45-degree orientation angle, as shown in Figure 2. The test specimens were taken from the grip of an ISO 527 1A tensile test bar. The surface roughness of the specimens prior to testing was better than RA = 0.2 μm. A chrome steel ball (B) (ISO 3290 G20, 12.7 mm diameter, surface roughness RA approximately 0.03 μm) was placed in the center and supported by the three plastic specimens. The ball-on-plate assembly was placed in an oil bath (C) (Castrol Edge 5W30) so that the contact points between the ball and the plastic were submerged in the oil. The entire assembly was then heated to the test temperature (120°C) and allowed to equilibrate for 30 minutes. A vertical load (1 N) was applied to the ball and the system was then allowed to stand for 10 minutes. -1 It was operated for 10 minutes (4.7 10 -3 (Sliding speed of 10 m / s). Next, a speed sweep is started, here 10-4 Friction was measured at a series of speed levels, from 1 m / s to 1 m / s. At each speed, the ball was slid over the plastic surface for at least 30 mm, and the CoF was reported as the average value over this distance.

[0165] [Wear resistance] The wear resistance of the molded test specimens was determined by assessing the depth of the mark on the test specimen with the deepest / best visible wear mark after measuring the coefficient of friction according to the ball-on-pyramid test.

[0166] [Examples and Comparative Examples] [Examples I to IX and Comparative Examples A to G] [Examples I, II, III (EX I, EX II, EX III)] EX I, EX II, and EX III were prepared according to the compositions in Table 1, where all compositions contained PA46 in combination with PA6 (4.5 wt%) and MAH-EP (5 wt%, 10 wt%, and 19 wt%).

[0167] [Comparative Examples A, B, C (CEX A, CEX B, CEX C)] CEX A and CEX B were prepared according to the compositions in Table 1. CEX C (Stanyl® HGR2) is a commercially available composition containing PA46 and PTFE.

[0168] [Examples IV, V, VI (EX IV, EX V, EX VI)] EX IV, EX V, and EX VI were prepared according to the compositions in Table 1, where all compositions comprised PA66 in combination with PA6 (4.5 wt%) and MAH-EP (5 wt%, 10 wt%, and 19 wt%).

[0169] [Comparative Examples D and E (CEX D and CEX E)] CEX D was prepared according to the composition in Table 1. CEX E (Leona™ 1542) is a commercially available composition containing PA66 and PTFE.

[0170] [Examples VII, VIII, IX (EX VII, EX VIII, EX IX)] EX VII, EX VIII, and EX IX were prepared according to the compositions in Table 1, where all compositions contained PPA in combination with PA6 (4.5 wt%) and MAH-EP (5 wt%, 10 wt%, and 19 wt%).

[0171] [Comparative Examples F and G (CEX F and CEX G)] CEX F and CEX G were prepared according to the compositions in Table 1.

[0172] result The results of the friction test are shown in Table 1.

[0173] The results of the physical and mechanical tests are shown in Table 2.

[0174] [Table 1]

[0175] The results in Table 1 show that the reference PA46, PA66, and PPA compositions (CEX A, CEX D, and CEX F, respectively) imparted high friction levels to the molded parts, and therefore are not suitable for use in sliding elements.

[0176] By adding increasing amounts of MAH-EP from 5 wt% up to 19 wt% to the above reference composition, and optionally adding an additional 4.5 wt% PA6, the friction levels of the molded parts were significantly reduced.

[0177] For example, in the pyramid ball test, the friction coefficients of EX I, EX II, and EX III were approximately 25% to 70% lower than that of CEX A evaluated at the same sliding speed. Similarly, in the pyramid ball test, the friction coefficients of EX IV, EX V, and EX VI were approximately 10% to 65% lower than that of CEX D evaluated at the same sliding speed. Furthermore, in the pyramid ball test, the friction coefficients of EX VII, EX XIII, and EX IX were approximately 20% to 75% lower than that of CEX F evaluated at the same sliding speed.

[0178] The effect of MAH-EP addition on friction levels was also demonstrated in a real-life application test (i.e., a chain-on-guide test) where a reduction in the coefficient of friction of about 5% to about 25% was observed, where the percent reduction is relative to the coefficient of friction of a molding composition including a reference composition evaluated at the same sprocket speed.

[0179] Furthermore, the inventors observed that the presented examples in most cases exhibited significantly improved friction levels over molded parts comprising commercially available compositions containing PTFE (CEX C and CEX E).

[0180] It was also observed that the friction levels of comparative examples CEX B and CEX G (containing MAH-EP but no PA6) were similar to that of their direct counterparts EX III and EX VII (comprising MAH-EP and PA6) when compared in the same test at the same speed level. However, when compared to CEX B and CEX G, EX III and EX VII exhibited advantageous physical and mechanical properties as shown in Table 2 below.

[0181] [Table 2]

[0182] The results in Table 2 show that the thermoplastic compositions of the present invention (EX III, EX V, EX VII) containing limited amounts of PA6 (i.e., 4.5 wt%) and varying amounts of MAH-EP had very good processability, which was a significant improvement over the thermoplastic compositions containing only MAH-EP (CEX B, CEX G) and even more significantly over the commercial compositions containing PTFE (CEX C and CEX E).

[0183] As a result, the degree of degradation of the thermoplastic compositions of the present invention was lower than that in the comparative examples (as shown by the viscosity numbers in Table 2). Specifically, the viscosity number of EX III was about 13% higher than that of CEX B, which is a significant improvement.

[0184] The results in Table 2 further demonstrate that the thermoplastic compositions of the present invention exhibited advantageous mechanical properties compared to the mechanical properties of the compositions of the comparative examples.

[0185] For example, compared to CEX B, the inventors surprisingly discovered that EX III exhibited significantly improved impact resistance (e.g., about a 90% increase in Izod notched impact strength testing at -20°C), flexural stiffness (e.g., about a 4% increase in tensile modulus at 23°C), and ductility (e.g., about a 50% increase in elongation at break at 120°C).

[0186] Furthermore, the inventors have discovered that the thermoplastic composition of the present invention has good abrasion resistance for its application in sliding elements.

[0187] In summary, the data showed that adding a limited amount (e.g., 4.5 wt%) of PA6 to a thermoplastic composition containing MAH-EP resulted in an improved thermoplastic composition that has very good processability and provides excellent sliding properties in combination with advantageous abrasion resistance and mechanical properties (such as impact resistance, bending stiffness, and ductility).The above advantages are particularly applicable and beneficial in industrial applications such as sliding elements.

[0188] [Examples X to XV and Comparative Examples H to I] [Examples X to XV (EX X to EX XV)] EX X to EX XV were prepared according to the compositions in Table 3, where all compositions contained PA46 in combination with PA6 (1 wt%, 2 wt%, 4.5 wt%, 6 wt%, 8 wt%, and 10 wt%) and MAH-EP (10 wt%). EX XII corresponds to EX II.

[0189] [Comparative Example H (CEX H)] CEX H was prepared according to the composition in Table 3, where the composition included PA46 in combination with PA6 (15 wt%) and MAH-EP (10 wt%).

[0190] Comparative Example I (CEX I) CEX I was prepared according to the composition in Table 3.

[0191] [result] The results of the friction, physical, and mechanical tests are shown in Table 3.

[0192] [Table 3]

[0193] The results in Table 3 show that adding PA6 in an amount increasing from 1 wt% up to 10 wt% to a composition containing PA46 and 10 wt% MAH-PE resulted in a composition that imparted excellent sliding properties to molded parts made therefrom. In other words, adding PA6 in an amount increasing from 1 wt% up to 10 wt% did not adversely affect the sliding performance of the resulting molded parts.

[0194] However, when compared to CEX H and CEX I, EX X and EX XV exhibited advantageous physical and mechanical properties as shown in Table 3 above.

[0195] The results in Table 3 show that the thermoplastic compositions of the present invention (EX X-EX XV) containing limited amounts of PA6, between 1 wt% and 10 wt%, and 10 wt% MAH-EP had very good processability, which was a significant improvement over the thermoplastic composition containing only 10 wt% MAH-EP (CEX I).

[0196] As a result, the degree of degradation of EX X to EX XV was lower than that of CEX I (as shown by the viscosity numbers in Table 3). Specifically, the viscosity numbers of EX X, EX XI, EX XII, EX XIII, EX XIV, and EX XV were approximately 2%, 4%, 6%, 8%, 11%, and 13% higher than that of CEX I.

[0197] The results in Table 3 further demonstrate that the thermoplastic compositions of the present invention exhibited advantageous mechanical properties compared to the mechanical properties of the compositions of the comparative examples.

[0198] For example, compared to CEX I, the inventors surprisingly discovered that EX X-EX XV had maintained or improved impact resistance, maintained or improved ductility, and improved flexural stiffness (e.g., about a 1-2% increase in tensile modulus at 23°C).

[0199] Furthermore, compared to CEX I, we showed that EX X-EX XV maintained good yield strength at 120° C. However, amounts of PA6 greater than 10 wt.% imparted significant loss of yield strength (i.e., loss of more than 10%) to molded parts (e.g., loss of about 14% at 15 wt.% PA6).

[0200] Furthermore, the inventors surprisingly discovered that EX X to EX XV had superior abrasion resistance compared to CEX H and CEX I. That is, EX X to EX XV had improved abrasion resistance compared to that of CEX I without PA6, and EX X to EX XV had improved abrasion resistance compared to that of CEX H containing 15 wt% PA6. Amounts of PA6 greater than 10 wt% imparted a significant loss of abrasion resistance.

[0201] In summary, the data showed that amounts of PA6 greater than 10 wt % had a detrimental effect on the overall performance of the resulting molded parts.

[0202] In summary, the data showed that adding limited amounts (e.g., 1% to 10% by weight) of PA6 to a thermoplastic composition containing 10% by weight of MAH-EP resulted in an improved thermoplastic composition that has very good processability and imparts excellent sliding properties to molded parts made therefrom, combined with advantageous wear resistance and mechanical properties (such as impact resistance, flexural rigidity, and ductility). The above advantages are particularly applicable and beneficial in industrial applications such as sliding elements.

[0203] [Examples XVI to XVIII and Comparative Examples J and K] [Examples XVI to XVIII (EX XVI to EX XVIII)] EX XVI-EX XVIII were prepared according to the compositions in Table 4, where all compositions contained PA66 in combination with PA6 (2 wt%, 4.5 wt%, and 10 wt%) and MAH-EP (10 wt%). EX XVII corresponds to EX V.

[0204] [Comparative Example J (CEX J)] CEX J was prepared according to the composition in Table 4, where the composition included PA66 in combination with PA6 (15 wt%) and MAH-EP (10 wt%).

[0205] [Comparative Example K (CEX K)] CEX K was prepared according to the composition in Table 4.

[0206] [result] The results of the friction, physical, and mechanical tests are shown in Table 4.

[0207] [Table 4]

[0208] The results in Table 4 show that adding PA6 in an amount increasing from 2 wt% up to 10 wt% to a composition containing PA66 and 10 wt% MAH-PE resulted in a composition that imparted excellent sliding properties to molded parts made therefrom. In other words, adding PA6 in an amount increasing from 2 wt% up to 10 wt% did not adversely affect the sliding performance of the resulting molded parts.

[0209] However, when compared to CEX J and CEX K, EX XVI and EX XVIII exhibited advantageous physical and mechanical properties as shown in Table 4 above.

[0210] The results in Table 4 show that the inventive thermoplastic compositions (EX XVI-EX XVIII) containing limited amounts of PA6, between 2 wt% and 10 wt%, and 10 wt% MAH-EP had very good processability, which was a significant improvement over the thermoplastic composition with only 10 wt% MAH-EP (CEX K).

[0211] As a result, the degree of degradation of EX XVI to EX XVIII was lower than that of CEX K (as shown by the viscosity numbers in Table 3). Specifically, the viscosity numbers of EX XVI, EX XVII, and EX XVIII were approximately 2%, 5%, and 10% higher than that of CEX K.

[0212] The results in Table 4 further demonstrate that the thermoplastic compositions of the present invention exhibited advantageous mechanical properties compared to the mechanical properties of the compositions of the comparative examples.

[0213] For example, when compared to CEX K, the inventors surprisingly discovered that EX XVI-EX XVIII had maintained impact resistance, maintained bending stiffness, and maintained or improved ductility.

[0214] Furthermore, compared to CEX K, we showed that EX XVI-EX XVIII maintained good yield strength at 120° C. However, amounts of PA6 greater than 10 wt.% imparted significant loss of yield strength (i.e., loss of more than 10%) to molded parts (e.g., loss of about 11% at 15 wt.% PA6).

[0215] Furthermore, compared to CEX J and CEX K, the inventors surprisingly discovered that EX XVI to EX XVIII maintained good abrasion resistance. That is, EX XVI to EX XVIII had improved abrasion resistance compared to the abrasion resistance of CEX K, which does not contain PA6. However, an amount of PA6 of about 10 wt. % (e.g., CEX J) imparted a significant loss of abrasion resistance.

[0216] In summary, the data showed that amounts of PA6 greater than 10 wt % had a detrimental effect on the overall performance of the resulting molded parts.

[0217] In summary, the data showed that adding limited amounts (e.g., 2% to 10% by weight) of PA6 to a thermoplastic composition containing 10% by weight of MAH-EP resulted in an improved thermoplastic composition that has very good processability and imparts excellent sliding properties to molded parts made therefrom in combination with favorable wear resistance and mechanical properties (such as impact resistance, flexural rigidity, and ductility). The above advantages are particularly applicable and beneficial in industrial applications such as sliding elements.

Claims

1. 1. A thermoplastic composition for use in a sliding element, comprising: 60 to 95% by weight of a first polyamide (a) which is an AA-BB type polyamide, 0.5 to 10% by weight of a second polyamide (b) which is an AB type polyamide, and 0.5 to 35 wt. % of a functionally modified polyolefin (c) wherein the weight percentages are based on the total weight of said thermoplastic composition.

2. 1. A thermoplastic composition for use in a sliding element, comprising: 70 to 85% by weight of a first polyamide (a) which is an AA-BB type polyamide, 0.5 to 10% by weight of a second polyamide (b) which is an AB type polyamide, and 0.5 to 25 wt. % of a functionally modified polyolefin (c) wherein the weight percentages are based on the total weight of said thermoplastic composition.

3. 3. Thermoplastic composition according to claim 1 or 2, wherein the composition comprises 1 to 10% by weight, preferably 2 to 10% by weight, of the second polyamide (b).

4. 3. Thermoplastic composition according to claim 1 or 2, wherein the composition comprises 2 to 8 wt. %, preferably 2 to 6 wt. %, of the second polyamide (b).

5. 3. Thermoplastic composition according to claim 1 or 2, wherein the composition comprises 4 to 8 wt. %, preferably 4 to 6 wt. %, of the second polyamide (b).

6. The thermoplastic composition according to any one of claims 1 to 5, wherein the composition comprises less than 5 wt% of the second polyamide (b).

7. 7. The thermoplastic composition according to any one of claims 1 to 6, wherein the composition comprises 1 to 25 wt%, preferably 1 to 20 wt%, more preferably 1 to 19 wt% of the functionally modified polyolefin (c).

8. 7. The thermoplastic composition according to any one of claims 2 to 6, wherein the composition comprises 5 to 25 wt%, preferably 8 to 20 wt%, more preferably 10 to 20 wt%, even more preferably 10 to 19 wt% of said functionally modified polyolefin (c).

9. 9. The thermoplastic composition according to any one of claims 1 to 8, wherein the first polyamide (a) has a melting temperature Tm-1 and the second polyamide (b) has a melting temperature Tm-2, Tm-2 being at least 30°C lower than Tm-1, preferably at least 50°C lower than Tm-1.

10. 10. The thermoplastic composition according to any one of claims 1 to 9, wherein the first polyamide (a) is selected from PA66, PA46, PA410, PA412, PA5T, PA6T, PA6T, PA6T / 6I, PA6T / 66, PA6T / 6, PA6T / 4T, PA6 / 66, PA66 / 6T / 6I, PA6T / DT-copolyamide, PA9T, PA9T / 2-MOMDT-copolyamide, PA10T, PA10T / 106, PA10T / 6T, PA46 / 6, copolyamides or mixtures thereof, and the second polyamide (b) is selected from PA6, PA7, PA8, PA9, PA10, PA11, PA12, copolyamides or mixtures thereof.

11. 11. The thermoplastic composition according to any one of claims 1 to 10, wherein the first polyamide (a) is selected from PA46, PA66, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) comprises PA6.

12. 12. Thermoplastic composition according to any one of claims 1 to 11, wherein the first polyamide (a) is selected from PA46, PA46 / 6, PA6T / 4T, PA6T / 4T / DT / DI, copolyamides or mixtures thereof, and the second polyamide (b) consists of PA6.

13. 13. The thermoplastic composition of any one of claims 1 to 12, wherein the functionally modified polyolefin (c) is selected from dicarboxylic anhydride modified polyolefins, epoxy modified polyolefins, or mixtures thereof, and the modified polyolefin has a melt flow rate in the range of 0.5 to 25 g / 10 min, measured according to ASTM standard D1238 (230°C, 2.16 kg load).

14. The thermoplastic composition of any one of claims 1 to 13, wherein the composition further comprises 0.01 to 5 wt% of a co-additive.

15. A sliding element for use in a lubricated sliding system, comprising a thermoplastic composition according to any one of claims 1 to 14.

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