Weather-resistant fiber-reinforced propylene composition

Abstract

A fiber-reinforced polymer composition is provided, comprising a polymer matrix comprising a propylene polymer. The polymer matrix comprises about 20% to about 90% by weight of the composition, and the composition further comprises a plurality of long reinforcing fibers distributed within the polymer matrix, the fibers comprising about 10% to about 60% by weight of the composition. The composition also includes a stabilizer system comprising a sterically hindered phenol antioxidant, a phosphite antioxidant, and a thioester antioxidant. [Selected Figure] Figure 1

Description

Technical Field

[0001]

[0001] This application claims priority to U.S. Application No. 62 / 637,675, filed Mar. 2, 2018 (which is hereby incorporated by reference in its entirety).

Background Art

[0002]

[0002] Automotive parts generally include a wide range of polymeric materials. For example, polypropylene materials are often used in automotive interior parts. However, one of the common problems manufacturers face when attempting to use such materials in automotive parts is that they tend to exhibit poor performance when exposed to high temperatures or ultraviolet light. To help develop more "weather-resistant" materials, various attempts have been made to introduce stabilizing systems into the compositions. Unfortunately, none of the systems have shown satisfactory performance to date. Accordingly, there is a current need for a polymeric composition that is weather-resistant in that it can better maintain a stable state after exposure to high temperature and / or ultraviolet light.

Summary of the Invention

[0003]

[0003] According to one embodiment of the present invention, a fiber-reinforced polymeric composition is disclosed that includes a polymeric matrix comprising a propylene polymer. The polymeric matrix constitutes from about 20 wt% to about 90 wt% of the composition, and the composition further includes a plurality of long reinforcing fibers distributed within the polymeric matrix, the fibers constituting from about 10 wt% to about 60 wt% of the composition. Further, the composition also includes a stabilizer system that includes a sterically hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant.

[0004] According to another embodiment of the present invention, a stabilizer system for use in a fiber-reinforced polymer composition is disclosed. The stabilizer system includes a sterically hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant. The weight ratio of the phosphite antioxidant to the sterically hindered phenolic antioxidant in the system is about 1:1 to about 5:1, the weight ratio of the thioester antioxidant to the sterically hindered phenolic antioxidant in the system is about 2:1 to about 10:1, and the weight ratio of the thioester antioxidant to the hindered phenolic antioxidant is about 2:1 to about 10:1.

[0005]

[0005] In the following, other features and aspects of the present invention are shown in more detail.

[0006] A complete and enabling disclosure of the present invention, including its best mode for those skilled in the art, is shown in more detail in the remainder of this specification, including reference to the accompanying drawings.

Brief Description of the Drawings

[0006]

Fig. 1

[0007] Figure 1 is a schematic view of one embodiment of a system that can be used to form a fiber-reinforced polymer composition of the present invention.

Fig. 2

[0008] Figure 2 is a cross-sectional view of an impregnation die that can be used in the system shown in Figure 1.

Mode for Carrying Out the Invention

[0007]

[0009] The repeated use of reference numerals in this specification and the drawings is intended to represent the same or similar features or components of the present invention.

[0010] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present invention.

[0008]

[0011] Generally speaking, the present invention relates to a weather-resistant fiber-reinforced composition for use in molded parts (e.g., injection-molded parts) that can exhibit good performance even after being exposed to various conditions (e.g., high temperatures). More specifically, the composition includes a plurality of long reinforcing fibers distributed within a polymer matrix that includes a propylene polymer. The long fibers can constitute, for example, about 10 wt% to about 60 wt% of the composition, in some embodiments about 15 wt% to about 55 wt%, and in some embodiments about 20 wt% to about 50 wt%. Also, the polymer matrix typically constitutes about 20 wt% to about 90 wt% of the composition, in some embodiments about 35 wt% to about 85 wt%, and in some embodiments about 50 wt% to about 80 wt%.

[0009]

[0012] The composition also includes a stabilizer system that includes a synergistic blend of various antioxidants including a hindered phenol antioxidant, a phosphite antioxidant, and a thioester antioxidant. The inventors have found that by selectively controlling the specific properties and concentrations of each of these components, the resulting composition can have excellent stability in mechanical properties even after being exposed to high temperatures. For example, initially, the composition measures about 15 kJ / m when measured at 23 °C in accordance with ISO test No. 179-1:2010 (technically equivalent to ASTM-D256-10e1). 2 Higher, and in some embodiments about 20 to about 80 kJ / m 2 and in some embodiments about 30 to about 60 kJ / m 2It can show the Charpy notchless impact strength. The initial tensile and flexural mechanical properties can also be good. For example, this composition can show a tensile strength of about 20 to about 300 MPa, in some embodiments about 30 to about 200 MPa, and in some embodiments about 40 to about 150 MPa; a tensile fracture strain of about 0.5% or more, in some embodiments about 0.6% to about 5%, and in some embodiments about 0.7% to about 2.5%; and / or a tensile modulus of about 3,500 MPa to about 20,000 MPa, in some embodiments about 4,000 MPa to about 15,000 MPa, and in some embodiments about 5,000 MPa to about 10,000 MPa. The tensile properties can be determined at 23°C or 80°C in accordance with ISO test No. 527-1:2012 (technically equivalent to ASTM-D638-14). This composition can also show an initial flexural strength of about 50 MPa to about 500 MPa, in some embodiments about 80 MPa to about 400 MPa, and in some embodiments about 100 MPa to about 250 MPa; and / or a flexural modulus of about 2,000 MPa to about 20,000 MPa, in some embodiments about 3,000 MPa to about 15,000 MPa, and in some embodiments about 4,000 MPa to about 10,000 MPa. The flexural properties can be determined at 23°C or 80°C in accordance with ISO test No. 178:2010 (technically equivalent to ASTM-D790-15e2).

[0010]

[0013] However, in particular, the inventors have also found that the present fiber-reinforced composition is not very sensitive to aging at high temperatures. For example, a component formed from the present fiber-reinforced composition can be aged for about 100 hours or more, in some embodiments about 300 hours to about 3000 hours, in some embodiments about 400 hours to about 2500 hours (e.g., about 1,000 hours) in an atmosphere having a temperature of about 100 °C or higher, in some embodiments about 120 °C to about 200 °C, in some embodiments about 130 °C to about 180 °C (e.g., 150 °C). Even after aging, the mechanical properties (e.g., impact strength, tensile properties, and / or flexural properties) can be maintained within the above ranges. For example, the ratio of certain mechanical properties (e.g., Charpy unnotched impact strength, flexural strength, etc.) after aging for 1,000 hours at 150 °C to the initial mechanical properties before such aging can be about 0.6 or more, in some embodiments about 0.7 or more, in some embodiments about 0.8 to 1.0. For example, in one embodiment, the component, after aging at a high temperature (e.g., 150 °C) for 1,000 hours, measures about 15 kJ / m 2 or higher, in some embodiments about 20 to about 80 kJ / m 2 , in some embodiments about 30 to about 60 kJ / m 2can exhibit Charpy notch - less impact strength. The component can also exhibit a flexural strength of about 50 to about 500 MPa, in some embodiments about 80 to about 400 MPa, and in some embodiments about 100 to about 250 MPa, when measured at a temperature of 23°C in accordance with ISO test No. 178:2010 (technically equivalent to ASTM - D790 - 15e2) after aging for 1,000 hours in a high - temperature atmosphere (e.g., 150°C). Additionally, the component can exhibit a tensile strength of about 20 to about 300 MPa, in some embodiments about 30 to about 200 MPa, and in some embodiments about 40 to about 150 MPa, when determined at a temperature of 23°C in accordance with ISO test No. 527 - 1:2012 (technically equivalent to ASTM - D638 - 14) after aging for 1,000 hours in a high - temperature atmosphere (e.g., 150°C).

[0011]

[0014] Similarly, the inventors have found that the present fiber - reinforced composition is not very sensitive to ultraviolet light. For example, a component formed from the fiber - reinforced composition can be exposed to ultraviolet light for one or more cycles. For example, in one embodiment, a sample can be subjected to 10 cycles (2800 kJ / m 2 or 280 kJ / m 2 ) per cycle. Even after such exposure, the mechanical properties (e.g., impact strength, tensile properties, and / or flexural properties) and the ratios of such properties can be maintained within the above - mentioned ranges.

[0012]

[0015] Here, various embodiments of the present invention will be described in more detail. I. Polymer Matrix: A. Polypropylene Polymer:

[0016] The polymer matrix functions as the continuous phase of the composition and includes one or more propylene polymers. Generally, any of a variety of propylene polymers or combinations of multiple propylene polymers can be used, such as propylene homopolymers (e.g., syndiotactic, atactic, isotactic, etc.), propylene copolymers (e.g., block copolymers, random copolymers, heterophase copolymers, etc.). For example, in one embodiment, a propylene polymer that is an isotactic or syndiotactic homopolymer can be used. The term "syndiotactic" generally refers to tacticity in which a significant portion, if not all, of the methyl groups are alternately arranged on opposite sides along the polymer chain. In contrast, the term "isotactic" generally refers to tacticity in which a significant portion, if not all, of the methyl groups are present on the same side along the polymer chain. Such homopolymers can have a melting point of about 160°C to about 170°C. In still other embodiments, a copolymer of propylene and an α-olefin monomer can be used. Specific examples of suitable α-olefin monomers include ethylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene having one or more methyl, ethyl, or propyl substituents; 1-hexene having one or more methyl, ethyl, or propyl substituents; 1-heptene having one or more methyl, ethyl, or propyl substituents; 1-octene having one or more methyl, ethyl, or propyl substituents; 1-nonene having one or more methyl, ethyl, or propyl substituents; ethyl-, methyl-, or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Ethylene is particularly preferred. The total propylene content of such copolymers can be about 60 wt% to about 99 wt%, in some embodiments about 70 wt% to about 97 wt%, and in some embodiments about 80 wt% to about 95 wt%. Also, the total α-olefin content can also range from about 1 wt% to about 40 wt%, in some embodiments from about 3 wt% to about 30 wt%, and in some embodiments from about 5 wt% to about 20 wt%.

[0013]

[0017] In some embodiments, the propylene polymer may be a heterophasic copolymer formed from at least two components (i.e., a matrix phase and a dispersed phase). The matrix phase typically comprises an isotactic propylene homopolymer, but relatively small amounts of an α-olefin comonomer such as up to about 10 wt%, in some embodiments up to about 6 wt%, and in some embodiments up to about 4 wt% can be used. Although not at all essential, including a small amount of comonomer can result in a product having lower stiffness but higher impact strength. Regardless of the particular polymer used, the matrix phase typically has a low xylene soluble content such as up to about 3 wt%, in some embodiments up to about 2 wt%, and in some embodiments up to about 1.5 wt%. The dispersed phase typically comprises a propylene / α-olefin copolymer (such as a propylene / ethylene copolymer) as described above. In the dispersed phase, the α-olefin content is generally present at a higher level than the total content of the above copolymer. For example, the α-olefin content of the dispersed phase may be from about 40 wt% to about 90 wt%, in some embodiments from about 45 wt% to about 85 wt%, and in some embodiments from about 50 wt% to about 80 wt%. Also, the propylene content of the dispersed phase may range from about 10 wt% to about 60 wt%, in some embodiments from about 15 wt% to about 55 wt%, and in some embodiments from about 20 wt% to about 50 wt%. Such heterophasic copolymers can be produced by melt compounding the individual polymer components, but typically it is desirable to produce them in a reactor. This is conveniently done by polymerizing propylene in a first reactor and transferring the highly crystalline propylene homopolymer from the first reactor into a second reactor where it is copolymerized with propylene and an α-olefin monomer (such as ethylene) in the presence of the homopolymer. Generally, any of a variety of known catalyst systems can be used to form the propylene polymer. For example, the polymer can be formed using free radical or coordination catalysts (such as Ziegler-Natta) or single site coordination catalysts (such as metallocene catalysts).

[0014]

[0018] The propylene polymer, usually determined according to ISO-1133-1:2011 (technically equivalent to ASTM-D1238-13), at a load of 2.16 kg and a temperature of 230 °C, has a melt flow index of about 20 to about 300 grams / 10 minutes or more, in some embodiments about 50 to about 250 grams / 10 minutes or less, and in some embodiments about 80 to about 160 grams / 10 minutes. Further, the propylene polymer can also exhibit a high degree of impact resistance. In this regard, the polymer, measured at 23 °C according to ISO Test No. 180:2000 (technically equivalent to ASTM-D256-10e1), is higher than about 20 kJ / m 2 and in some embodiments about 30 to about 100 kJ / m 2 and in some embodiments about 40 to about 80 kJ / m 2 of Izod notched impact strength. In particular, the polymer can retain a significant portion of this strength even at extreme temperatures. For example, the ratio of the Izod notched impact strength at -20 °C to the impact strength at 23 °C can be about 0.6 or more, in some embodiments about 0.6 or more, and in some embodiments about 0.7 to 1.0. For example, in one embodiment, the propylene polymer, measured at 23 °C according to ISO Test No. 180:2000 (technically equivalent to ASTM-D256-10e1), is higher than about 15 kJ / m 2 and in some embodiments about 20 to about 80 kJ / m 2 and in some embodiments about 30 to about 50 kJ / m 2 of Izod notched impact strength at -20 °C.

[0015] B. Stabilizer system:

[0019] As described above, the stabilizer system of the present invention uses a synergistic combination of various antioxidants including a sterically hindered phenol antioxidant, a phosphite antioxidant, and a thioester antioxidant. That is, the weight ratio of the phosphite antioxidant to the hindered phenol antioxidant is generally about 1:1 to about 5:1, in some embodiments about 1:1 to about 4:1, and in some embodiments about 1.5:1 to about 3:1 (e.g., about 2:1). The weight ratio of the thioester stabilizer to the phosphite antioxidant is also generally about 1:1 to about 5:1, in some embodiments about 1:1 to about 4:1, and in some embodiments about 1.5:1 to about 3:1 (e.g., about 2:1). Also, the weight ratio of the thioester antioxidant to the hindered phenol antioxidant is also generally about 2:1 to about 10:1, in some embodiments about 2:1 to about 8:1, and in some embodiments about 3:1 to about 6:1 (e.g., about 4:1). Within these selected ratios, it is believed that the composition can achieve a unique ability to maintain a stable state even after exposure to high temperatures and / or ultraviolet light.

[0016] i. Sterically hindered phenol:

[0020] The sterically hindered phenol is usually present in the composition in an amount of about 0.01 to about 1 wt% of the polymer composition, in some embodiments about 0.02 wt% to about 0.5 wt%, and in some embodiments about 0.05 wt% to about 0.3 wt%. Although various different compounds can be used, particularly suitable hindered phenol compounds have the following general structures (IV), (V), and (VI):

[0017]

Chemical formula

[0018] (Wherein, a, b, and c are independently in the range of 1 to 10, and in some embodiments 2 to 6; R 8 、R 9 、R 10 、R 11 、and R 12is, independently, hydrogen, C1-C 10 alkyl, and C3-C 30 branched alkyl, for example, selected from methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl groups; R 13 R 14 and R 15 are, independently, the following general structures (VII) and (VIII):

[0019]

Chemical formula

[0020] (wherein, d is from 1 to 10, and in some embodiments is in the range of 2 to 6; R 16 R 17 R 18 and R 19 are, independently, hydrogen, C1-C 10 alkyl, and C3-C 30 branched alkyl, for example, selected from methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl groups) selected from the groups represented by one of) having one of).

[0021]

[0021] As specific examples of suitable hindered phenols having the general structure shown above, for example, 2,6-di-tert-butyl-4-methylphenol; 2,4-di-tert-butylphenol; pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; octadecyl 3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate; tetrakis[methylene(3,5-di-tert-butyl-4-hydroxycinnamate)]methane; bis-2,2’-methylene-bis(6-tert-butyl-4-methylphenol) terephthalate; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate; 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl); 1,3,5-triazine-2,4,6-(1H,3H,5H)-trione; 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane; 1,3,5-triazine-2,4,6(1H,3H,5H)-trione; 1,3,5-tris[[3,5-bis-(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]; 4,4’,4”-[(2,4,6-trimethyl-1,3,5-benzenetriyl)tris-(methylene)]tris[2,6-bis(1,1-dimethylethyl)]; 6-tert-butyl-3-methylphenyl; 2,6-di-tert-butyl-p-cresol; 2,2’-methylenebis(4-ethyl-6-tert-butylphenol); 4,4’-butylidenebis(6-tert-butyl-m-cresol); 4,4’-thiobis(6-tert-butyl-m-cresol); 4,4’-dihydroxydiphenyl-cyclohexane; alkylated bisphenol; styrenated phenol; 2,6-di-tert-butyl-4-methylphenol; n-octadecyl 3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate; 2,2’-methylenebis(4-methyl-6-tert-butylphenol); 4,4’-thiobis(3-methyl-6-tert-butylphenyl);4,4'-butylidenebis(3-methyl-6-tert-butylphenol); stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane; stearyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, etc.; and mixtures thereof can be mentioned.

[0022]

[0022] Particularly preferred compounds are those having the general formula (VI) such as tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, which is commercially available under the name Irganox® 3114.

[0023] ii. Phosphite:

[0023] Phosphite antioxidants are usually present in the composition in an amount of about 0.02 to about 2% by weight of the polymer composition, in some embodiments about 0.04% to about 1% by weight, and in some embodiments about 0.1% to about 0.6% by weight. Examples of phosphite antioxidants include various different compounds such as aryl monophosphites, aryl diphosphites, etc., and mixtures thereof. For example, the following general structure (IX):

[0024]

Chemical formula

[0025] (wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10 are each independently hydrogen, C1-C 10 alkyl, and C3-C 30 branched alkyl, for example, selected from methyl, ethyl, propyl, isopropyl, butyl, or tert-butyl groups) Aryl diphosphites having the following can be used.

[0026]

[0024] Examples of such aryl diphosphite compounds include, for example, bis(2,4-dicumylphenyl)pentaerythritol diphosphite (commercially available as Doverphos® S-9228), and bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (commercially available as Ultranox® 626). Also, examples of suitable aryl monophosphites include tris(2,4-di-tert-butylphenyl) phosphite (commercially available as Irgafos® 168); bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite (commercially available as Irgafos® 38), and the like.

[0027] iii. Thioester:

[0025] Thioester antioxidants are usually present in the polymer composition in an amount of about 0.04 to about 4% by weight, in some embodiments about 0.08% to about 2% by weight, and in some embodiments about 0.2% to about 1.2% by weight. A particularly suitable thioester antioxidant for use in the present invention has the following general structure: R 11 -O(O)(CH2) x -S-(CH2) y (O)-R 12 (wherein, x and y are independently 1 to 10, in some embodiments 1 to 6, and in some embodiments 2 to 4 (for example 2); R 11 and R 12 are independently linear or branched C6-C 30 alkyl, in some embodiments C 10 -C 24 alkyl, in some embodiments C 12 -C 20(selected from alkyl such as lauryl, stearyl, octyl, hexyl, decyl, dodecyl, oleyl, etc.) is a thiocarboxylic acid ester such as those having

[0028]

[0026] Specific examples of suitable thiocarboxylic acid esters include, for example, distearyl thiodipropionate (commercially available as Irganox® PS 800), dilauryl thiodipropionate (commercially available as Irganox® PS 802), di-2-ethylhexyl-thiodipropionate, diisodecyl thiodipropionate, and the like.

[0029] C. Other components: In addition to the propylene polymer and the antistatic agent, the polymer matrix can also contain various other components. Examples of such optional components include, for example, compatibilizers, stabilizers (such as ultraviolet light stabilizers, light stabilizers, heat stabilizers, etc.), particulate fillers, lubricants, colorants, flowability modifiers, and other materials added to improve properties and processability. For example, in some embodiments, a UV stabilizer can be included in the composition. Suitable UV stabilizers include, for example, benzophenone (such as (2-hydroxy-4-(octyloxy)phenyl)phenyl, methanone (Chimassorb® 81)), benzotriazole (such as 2-(2-hydroxy-3,5-di-α-cumylphenyl)-2H-benzotriazole (Tinuvin® 234), 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole (Tinuvin® 329), 2-(2-hydroxy-3-α-cumyl-5-tert-octylphenyl)-2H-benzotriazole (Tinuvin® 928), etc.), triazine (such as 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-s-triazine (Tinuvin® 1577), hindered amine (such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin® 770), or a polymer of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine (Tinuvin® 622), etc., and mixtures thereof. When used, such UV stabilizers typically constitute about 0.05 wt% to about 2 wt% of the composition, about 0.1 wt% to about 1.5 wt% in some embodiments, and about 0.2 wt% to about 1.0 wt% in some embodiments.

[0030] The polymer composition may also include pigments such as titanium dioxide, ultramarine blue, cobalt blue, phthalocyanine, anthraquinone, carbon black, metallic pigments, and mixtures thereof. Such pigments typically constitute from about 0.01% to about 3% by weight of the composition, and in some embodiments from about 0.5% to about 2% by weight. If desired, a compatibilizer can be used to increase the degree of adhesion between the long fibers and the propylene polymer. When used, such compatibilizer typically constitutes from about 0.1% to about 15% by weight of the polymer composition, in some embodiments from about 0.5% to about 10% by weight, and in some embodiments from about 1% to about 5% by weight. In some embodiments, the compatibilizer may be a polyolefin compatibilizer comprising a polyolefin modified with a polar functional group. The polyolefin may be a homopolymer of an olefin (such as polypropylene), or a copolymer (such as an ethylene copolymer, a propylene copolymer, etc.). The functional group can be grafted onto the polyolefin backbone or introduced as a monomer component of a polymer (such as a block or random copolymer). Particularly suitable functional groups include maleic anhydride, maleic acid, fumaric acid, maleimide, maleic hydrazide, reaction products of maleic anhydride and diamines, dichloromaleic anhydride, maleic amide, and the like.

[0031] Regardless of the specific components used, the raw materials (e.g., propylene polymers, stabilization systems, compatibilizers, etc.) are typically melt blended together before being reinforced with long fibers. The raw materials can be fed into the melt blending apparatus that dispersively blends the materials either simultaneously or sequentially. Batch and / or continuous melt blending techniques can be used. For example, mixers / kneaders, Banbury mixers, Farrell continuous mixers, single-screw extruders, twin-screw extruders, roll mills, etc. can be utilized to blend the materials. One particularly preferred melt blending apparatus is a co-rotating twin-screw extruder (e.g., the ZSK-30 twin-screw extruder available from Werner & Pfleider Corporation of Ramsey N.J.). Such an extruder can include feed ports and vent ports and can provide high-intensity distributive and dispersive mixing. For example, the propylene polymer can be fed into the feed port of the twin-screw extruder and melted. Thereafter, antioxidants and / or stabilizers can be injected into the polymer melt. Alternatively, the antioxidants and / or stabilizers can be fed separately at different positions along the length of the extruder. Regardless of the specific melt blending technique selected, the raw materials are blended under high shear / pressure and heat to ensure sufficient mixing. For example, the melt blending can be carried out at a temperature of about 150°C to about 300°C, in some embodiments about 155°C to about 250°C, and in some embodiments about 160°C to about 220°C.

[0032] As described above, some embodiments of the present invention contemplate using blends of multiple polymers (e.g., propylene homopolymers and / or propylene / α-olefin copolymers) within a polymer matrix. In such embodiments, each of the polymers used in the blend can be melt blended by the methods described above. However, in still other embodiments, it may be desirable to melt blend a first propylene polymer (e.g., a homopolymer or copolymer) to form a concentrate, which is then reinforced with long fibers by the methods described below to form a precursor composition. The precursor composition can then be blended (e.g., dry blended) with a second propylene polymer to form a fiber-reinforced composition having the desired properties. It should also be understood that additional polymers can be added before and / or during the reinforcement of the polymer matrix with long fibers.

[0033] II. Long Fibers:

[0031] To form the fiber-reinforced compositions of the present invention, generally, long fibers are encapsulated within a polymer matrix. The term "long fibers" generally refers to fibers, filaments, yarns, or rovings (e.g., bundles of fibers) that are not continuous and have a length of about 1 to about 25 millimeters, in some embodiments about 1.5 to about 20 millimeters, in some embodiments about 2 to about 15 millimeters, and in some embodiments about 3 to about 12 millimeters. As described above, due to the unique properties of the composition, a significant portion of the fibers can maintain a relatively large length even after being formed into a molded part (e.g., injection molding). That is, the median length (D50) of the fibers in the composition can be about 1 millimeter or greater, in some embodiments about 1.5 millimeters or greater, in some embodiments about 2.0 millimeters or greater, and in some embodiments about 2.5 to about 8 millimeters.

[0034]

[0032] The fibers can be formed from any conventional material known in the art, such as metallic fibers; glass fibers (e.g., E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S1-glass, S2-glass), carbon fibers (e.g., graphite), boron fibers, ceramic fibers (e.g., alumina or silica), aramid fibers (e.g., Kevlar®), synthetic organic fibers (e.g., polyamide, polyethylene, paraphenylene, terephthalamide, polyethylene terephthalate, and polyphenylene sulfide), and various other natural or synthetic inorganic or organic fiber materials known for strengthening thermoplastic compositions. Glass fibers and carbon fibers are particularly desirable. Such fibers often have a nominal diameter of about 4 to about 35 micrometers, and in some embodiments about 9 to about 35 micrometers. The fibers may be twisted or straight. If desired, the fibers may be in the form of rovings (e.g., bundles of fibers) containing a single fiber type or multiple different types of fibers. Different fibers can be included in individual rovings, or different types of fibers can be included in each roving. For example, in one embodiment, some rovings can contain carbon fibers while other rovings can contain glass fibers. The number of fibers contained in each roving may be constant or may vary from roving to roving. Typically, rovings can contain from about 1,000 fibers to about 50,000 individual fibers, and in some embodiments from about 2,000 to about 40,000 fibers.

[0035]

[0033] Generally, any of a variety of different techniques can be used to introduce fibers into a polymer matrix. The long fibers can be randomly distributed within the polymer matrix or distributed in an aligned manner. For example, in one embodiment, the continuous fibers are first impregnated into the polymer matrix to form an extrudate, which is then cooled and then cut into pellets such that the resulting fibers have the desired length for the long fibers. In such an embodiment, the polymer matrix and the continuous fibers (e.g., rovings) are typically drawn through an impregnation die to achieve the desired contact between the fibers and the polymer. The drawing process also helps to ensure that the fibers are separated and oriented in the longitudinal direction parallel to the major axis (e.g., length) of the pellet, thereby further increasing the mechanical properties. For example, referring to FIG. 1, one embodiment of a drawing process 10 is shown, where the polymer matrix is supplied from an extruder 13 to an impregnation die 11, while the continuous fibers 12 are pulled through the die 11 by a puller device 18 to produce a composite structure 14. Examples of conventional puller devices include, for example, caterpillar pullers and reciprocating pullers. Optionally, the composite structure 14 can also be pulled through a coating die 15 attached to an extruder 16 (through which a coating resin is applied to form a coated structure 17). As shown in FIG. 1, the coated structure 17 is then pulled by a puller assembly 18 and supplied to a pelletizer 19, where the structure 17 is cut to the desired dimensions to form a long fiber reinforced composition.

[0036]

[0034] The properties of the impregnation die used during the draw forming process can be selectively varied to help achieve good contact between the polymer matrix and the long fibers. Examples of suitable impregnation die systems are described in detail in Hawley's Reissue Patent No. 32,772; Regan et al.'s No. 9,233,486; and Eastep et al.'s No. 9,278,472. Referring to FIG. 2, for example, one embodiment of such a suitable impregnation die 11 is shown. As shown, the polymer matrix 127 can be supplied to the impregnation die 11 via an extruder (not shown). More specifically, the polymer matrix 127 can be discharged from the extruder through the barrel flange 128 and introduced into the die flange 132 of the die 11. The die 11 includes an upper die half 134 that meshes with a lower die half 136. Continuous fibers 142 (e.g., rovings) are supplied from a reel 144 through a supply port 138 to the upper die half 134 of the die 11. Similarly, continuous fibers 146 are also supplied from a reel 148 through a supply port 140. The matrix 127 is heated inside the die halves 134 and 136 by heaters 133 mounted within the upper die half 134 and / or the lower die half 136. The die generally operates at a temperature sufficient to cause melting and impregnation of the thermoplastic polymer. Usually, the operating temperature of the die is higher than the melting point of the polymer matrix. When processed in this way, the continuous fibers 142 and 146 become encapsulated in the matrix 127. Next, this mixture is pulled through the impregnation die 11 to produce a fiber-reinforced composition 152. Optionally, the pressure near the impregnation die 11 can be sensed by a pressure sensor 137 to enable control over the extrusion speed by controlling the rotational speed of the screw shaft or the feed rate of the feeder.

[0037]

[0035] Within the impregnation die, it is generally desirable for the fibers to contact a series of collision zones. In these zones, the polymer melt can be flowed laterally through the fibers to generate shear and pressure, thereby greatly increasing the degree of impregnation. This is particularly useful when forming composites from high fiber content ribbons. Usually, the die includes at least 2 collision zones per roving, at least 3 in some embodiments, and 4 - 50 collision zones in some embodiments, in order to generate a sufficient degree of shear and pressure. Their specific forms can be varied, but the collision zones usually have a curved surface such as a curved protrusion, rod, etc. The collision zones are also usually made of a metallic material.

[0038]

[0036] FIG. 2 shows a partial enlarged schematic view of an impregnation die 11 including a plurality of collision zones in the form of protrusions 182. It should be understood that the present invention can be implemented using a plurality of supply ports that may optionally be coaxial with the machine direction. The number of supply ports used can be varied according to the number of fibers processed at one time within the die, and the supply ports can be mounted within the upper die half 134 or the lower die half 136. The supply port 138 includes a sleeve 170 mounted within the upper die half 134. The supply port 138 is slidably mounted within the sleeve 170. The supply port 138 is divided into at least two pieces shown as pieces 172 and 174. The supply port 138 has a longitudinally extending bore 176. The bore 176 can be shaped as a straight circular cone opening spaced from the upper die half 134. The fibers 142 pass through the bore 176 and are introduced into the passage 180 between the upper die half 134 and the lower die half 136. Also, a series of protrusions 182 are formed within the upper die half 134 and the lower die half 136 such that the passage 210 takes a spiral path. The protrusions 182 cause the fibers 142 and 146 to pass over at least one protrusion so that the polymer matrix inside the passage 180 comes into sufficient contact with each fiber. In this way, sufficient contact between the molten polymer and the fibers 142 and 146 is ensured.

[0039]

[0037] To further promote impregnation, the fibers can also be maintained under tension while present within the impregnation die. The tension can be, for example, in the range of about 5 to about 300 Newtons per tow of fiber, in some embodiments about 50 to about 250 Newtons, and in some embodiments about 100 to about 200 Newtons. Further, the fibers can also be passed through the collision zone in a tortuous path to increase shear. For example, in the embodiment shown in FIG. 2, the fibers cross the collision zone in a sine wave type path. The angle at which the roving crosses from one collision zone to another is generally high enough to increase shear, but not so high as to cause excessive force to break the fibers. Thus, for example, this angle can be in the range of about 1° to about 30°, and in some embodiments about 5° to about 25°.

[0040]

[0038] The impregnation die described above is just one of the various possible configurations that can be used in the present invention. For example, in another embodiment, the fibers can be introduced into a crosshead die that is arranged at an angle with respect to the direction of flow of the polymer melt. When the fibers move through the crosshead die and reach the position where the polymer is discharged from the extruder barrel, the polymer is forced into contact with the fibers. It should also be understood that any other extruder design, such as a twin screw extruder, can be used. Further, in some cases, other components can be used to assist in the impregnation of the fibers. For example, in some embodiments, a "gas jet" assembly can be used to help spread individual fiber bundles or tows, each of which can contain up to 24,000 fibers, evenly across the full width of the combined tows. This helps to achieve a uniform distribution of strength properties within the ribbon. Such an assembly can include a supply of compressed air or other gas that impinges generally perpendicular to the moving fiber tows passing through the exit ports. The spread fiber bundles can then be introduced into the die for impregnation as described above.

[0041] III. Molded Parts:

[0039] This fiber-reinforced composition can generally be used to form molded parts using various different techniques. Suitable techniques include, for example, injection molding, low-pressure injection molding, extrusion compression molding, gas injection molding, foam injection molding, low-pressure gas injection molding, low-pressure foam injection molding, gas extrusion compression molding, foam extrusion compression molding, extrusion molding, foam extrusion molding, compression molding, foam compression molding, gas compression molding, and the like. For example, an injection molding system including a mold into which the fiber-reinforced composition can be injected can be used. The time inside the injection machine can be controlled and optimized so that the polymer matrix does not solidify prematurely. When the cycle time is reached and the barrel is full for ejection, a piston can be used to inject the composition into the mold cavity. A compression molding system can also be used. Similar to injection molding, the molding of the fiber-reinforced composition into the desired article is also carried out in a mold. The composition can be placed into the compression mold using any known technique, for example, by being picked up by an automated robot arm. The temperature of the mold can be maintained above the solidification temperature of the polymer matrix for a desired time to enable solidification. Next, the molded article can be solidified by bringing it to a temperature lower than its melting point. The resulting product can be demolded. The cycle time for each molding process can be adjusted to be compatible with the polymer matrix, to achieve sufficient bonding, and to enhance the productivity of the overall process.

[0042] Regardless of the shaping technique used, a wide range of parts can be formed from the fiber-reinforced composition of the present invention. For example, the inventors have found that relatively thin molded parts (e.g., injection molded parts) can be easily formed from the resulting composition. For example, the parts can have a thickness of about 4 millimeters or less, in some embodiments about 2.5 millimeters or less, in some embodiments about 2 millimeters or less, in some embodiments about 1.8 millimeters or less, and in some embodiments about 0.1 to about 1.6 millimeters (e.g., 1.2 millimeters). Due to the thin nature of the parts that can be formed, the present fiber-reinforced composition is particularly well-suited for use in automotive interior and exterior parts (e.g., injection molded parts). Suitable automotive exterior parts include, for example, fan shrouds, sunroof systems, door panels, front end modules, side body panels, underbody shields, bumper panels, claddings (e.g., near the rear door number plate), cowls, spray nozzle bodies, capturing hose assemblies, pillar covers, rocker panels, and the like. Also, suitable automotive interior parts that can be formed from the fiber-reinforced composition of the present invention include, for example, pedal modules, instrument panels (e.g., dashboards), armrests, consoles (e.g., center consoles), seat structures (e.g., the backrest of a rear bench or seat covers), interior modules (e.g., trims, body panels, or door modules), lift gates, interior organizers, step assists, ashtrays, glove boxes, gear shift levers, and the like. Other suitable parts include siding panels, fence spike parts, end caps, joints, hinges, interior and exterior decorative trim boards, composite roof boards, slates, shakes, or panels, and the like.

Examples

[0043]

[0041] The present invention can be better understood by referring to the following examples. Test method:

[0042] Melt Flow Index: The melt flow index of the polymer or polymer composition can be determined at a load of 2.16 kg and a temperature of 230°C in accordance with ISO-1133-1:2011 (technically equivalent to ASTM-D1238-13).

[0044]

[0043] Tensile Modulus, Tensile Stress, and Elongation at Break: Tensile properties can be tested in accordance with ISO Test No. 527:2012 (technically equivalent to ASTM-D638-14). Elastic modulus and strength can be measured for the same specimen sample having a length of 80 mm, a thickness of 10 mm, and a width of 4 mm. The test temperature may be 23°C or 150°C, and the test speed may be 1 or 5 mm / min.

[0045]

[0044] Flexural Modulus, Elongation at Break in Flexure, and Flexural Stress: Flexural properties can be tested in accordance with ISO Test No. 178:2010 (technically equivalent to ASTM-D790-15e2). This test can be performed with respect to a support span of 64 mm. The test can be performed on the central portion of an uncut ISO-3167 multipurpose bar. The test temperature may be 23°C or 150°C, and the test speed may be 2 mm / min.

[0046]

[0045] Izod Impact Strength without Notch and with Notch: Izod properties can be tested in accordance with ISO Test No. 179-1:2010 (technically equivalent to ASTM-D256-10, Method B). This test can be performed using a specimen dimension of Type 1 (length of 80 mm, width of 10 mm, and thickness of 4 mm). When testing the notched impact strength, the notch may be a Type A notch (bottom radius of 0.25 mm). The specimen can be cut out from the central portion of a multipurpose bar using a single-flute milling cutter. The test temperature may be 23°C or -30°C.

[0047]

[0046] Heat Deflection Temperature (DTUL): The heat deflection temperature can be determined in accordance with ISO test No. 75-2:2013 (technically equivalent to ASTM-D648-07). More specifically, a test specimen sample having a length of 80 mm, a thickness of 10 mm, and a width of 4 mm can be subjected to a three-point bending test in the longitudinal direction with a specified load (maximum outer fiber stress) of 1.8 megapascals. The test specimen can be lowered into a silicone oil bath, where the temperature is raised at a rate of 2 °C / min until it is distorted by 0.25 mm (0.32 mm for ISO test No. 75-2:2013).

[0048] Example 1:

[0047] A sample is formed that includes approximately 47.8 wt% of a propylene homopolymer (melt flow index of 65 g / 10 min, density of 0.902 g / cm 3 ), 1 wt% of a coupling agent, 0.8 wt% of a black pigment, 0.4 wt% of a stabilizer, and 50 wt% of continuous glass fiber rovings (2400 tex, filament diameter of 16 μm). The stabilizer included 44 wt% of Irganox® 1010, 10.1 wt% of Irgafos® 168, 2 wt% of Chimassorb® 234, and 44 wt% of Ultranox® 626. The sample is melt processed in a single-screw extruder (90 mm) with a melt temperature of 265 °C, a die temperature of 330 °C, a zone temperature range of 160 °C to 320 °C, and a screw speed of 160 rpm.

[0049] Example 2:

[0048] A sample is formed as described in Example 1, except that 0.35 wt% of a blend of 14.3 wt% of Irganox® 3114, 28.6 wt% of Ultranox® 626, and 57.1 wt% of Irganox® PS 802 is included.

[0050] Example 3: A sample is formed as described in Example 1, except that 0.53 wt% of a blend of 14.3 wt% Irganox® 3114, 28.6 wt% Ultranox® 626, and 57.1 wt% Irganox® PS 802 is included.

[0051] Example 4: A sample is formed as described in Example 1, except that 0.70 wt% of a blend of 14.3 wt% Irganox® 3114, 28.6 wt% Ultranox® 626, and 57.1 wt% Irganox® PS 802 is included.

[0052]

[0051] The samples of Examples 1 to 4 were tested for tensile strength before and after aging at 150 °C. The results are shown below.

[0053]

Table 1

[0054] Example 5:

[0052] A sample is formed that contains approximately 47.6 wt% propylene homopolymer (melt flow index of 65 g / 10 min, density of 0.902 g / cm 3 ), 1 wt% coupling agent, 0.8 wt% black pigment, 0.6 wt% stabilizer, and 50 wt% continuous glass fiber rovings (2400 tex, filament diameter of 16 μm). The stabilizer contained 19.5 wt% Irganox® 1010, 11 wt% Irgafos® 168, 0.5 wt% Chimassorb® 234, 57.9 wt% Chimassorb® 944, and 11 wt% Ultranox® 626. The sample is melt processed in a single screw extruder (90 mm) with a melt temperature of 265 °C, a die temperature of 330 °C, a zone temperature in the range of 160 °C to 320 °C, and a screw speed of 160 rpm.

[0055] Example 6:

[0053] A sample is formed that includes approximately 47.8 wt% propylene homopolymer (melt flow index of 65 g / 10 min, density of 0.902 g / cm 3 ), 1 wt% coupling agent, 0.8 wt% black pigment, 0.4 wt% stabilizer, and 50 wt% continuous glass fiber rovings (2400 tex, filament diameter of 16 μm). The stabilizer included 9 wt% Irganox® 3114, 26 wt% Ultranox® 626, and 65 wt% Irganox® PS 802. The sample is melt processed in a single screw extruder (90 mm) with a melt temperature of 265 °C, a die temperature of 330 °C, a zone temperature range of 160 °C to 320 °C, and a screw speed of 160 rpm.

[0056] Example 7:

[0054] A sample is formed as described in Example 1, except that 0.58 wt% of a blend of 5.9 wt% Irganox® 3114, 17 wt% Ultranox® 626, 34.5 wt% Chimmassorb® 81, and 42.6 wt% Irganox® PS 802 is included.

[0057]

[0055] The samples of Examples 5 - 7 were tested for tensile strength before and after aging at 150 °C. The results are shown below.

[0058]

Table 2

[0059]

[0056] These and other modifications and variations of the present invention can be made by those skilled in the art without departing from the spirit and scope of the invention. Further, it should be understood that the various aspects of the embodiments can be exchanged wholly or in part. Further, those skilled in the art will understand that the above description is for illustrative purposes only and is not intended to limit the invention as further described in the appended claims. The description of the claims at the time of filing is shown below. [Claim 1] A fiber-reinforced polymer composition comprising a polymer matrix comprising a propylene polymer and an antistatic agent, constituting about 20% to about 90% by weight of the composition; a plurality of long reinforcing fibers distributed within the polymer matrix, constituting about 10% to about 60% by weight of the composition; and a stabilizer system comprising a sterically hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant; said fiber-reinforced polymer composition. [Claim 2] The fiber-reinforced polymer composition according to claim 1, wherein the weight ratio of the phosphite antioxidant to the sterically hindered phenolic antioxidant is about 1:1 to about 5:1. [Claim 3] The fiber-reinforced polymer composition according to claim 1, wherein the weight ratio of the thioester antioxidant to the sterically hindered phenolic antioxidant is about 2:1 to about 10:1. [Claim 4] The fiber-reinforced polymer composition according to claim 1, wherein the weight ratio of the thioester antioxidant to the sterically hindered phenolic antioxidant is about 2:1 to about 10:1. [Claim 5] The fiber-reinforced polymer composition according to claim 1, wherein the sterically hindered phenolic antioxidant is present in the composition in an amount of about 0.01% to about 1% by weight. [Claim 6] The sterically hindered phenolic antioxidant has the following general structures (IV), (V), and (VI): [Chemical formula] (wherein a, b, and c are independently in the range of 1 to 10; R 8 , R 9 , R 10 , R 11 , and R 12 are independently hydrogen, C1-C 10 alkyl, and C3-C 30selected from branched alkyl; R 13 、R 14 、and R 15 are independently of the following general structures (VII) and (VIII):

Chemical formula

Chemical formula

Claims

1. A fiber-reinforced polymer composition comprising: a polymer matrix comprising a propylene polymer and constituting 20 wt% to 90 wt% of the composition; a plurality of long reinforcing fibers distributed within the polymer matrix and constituting 10 wt% to 60 wt% of the composition; and a stabilizer system comprising a sterically hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant; wherein the weight ratio of the phosphite antioxidant to the sterically hindered phenolic antioxidant is from 1:1 to 5:1, and the composition does not contain any of 3-(N-salicyloyl)amino-1,2,4-triazole, 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, and 2,2'-oxamidobis[ethyl 3-(3,5-tert-butyl-4-hydroxyphenyl)propionate], and the total content of all components including the polymer matrix, the long reinforcing fibers, and the stabilizer system in the fiber-reinforced polymer composition is 100 wt%, the fiber-reinforced polymer composition.

2. The fiber-reinforced polymer composition according to claim 1, wherein the weight ratio of the thioester antioxidant to the sterically hindered phenolic antioxidant is from 2:1 to 10:

1.

3. The fiber-reinforced polymer composition according to claim 1, wherein the weight ratio of the thioester antioxidant to the phosphite antioxidant is from 1:1 to 5:

1.

4. The fiber-reinforced polymer composition according to claim 1, wherein the sterically hindered phenolic antioxidant is present in the composition in an amount of 0.01 to 1 wt%.

5. The sterically hindered phenolic antioxidant has one of the following general structures (IV), (V), and (VI): 【Chemical 1】 wherein a, b, and c are independently in the range of 1 to 10; R ８ 、R ９ 、R １０ 、R １１ 、and R １２ are, independently, hydrogen, C １ -C １０ alkyl, and C ３ -C ３０ branched alkyl; R １３ , R １４ , and R １５ are, independently, the following general structures (VII) and (VIII): 【Chemical 2】 wherein d is in the range of 1 to 10; R １６ 、R １７ 、R １８ 、and R １９ are, independently, hydrogen, C １ to C １０ alkyl, and C ３ to C ３０ (selected from branched alkyl) (selected from the groups represented by one of the following) The fiber-reinforced polymer composition according to claim 1 having one of the above.

6. The fiber-reinforced polymer composition according to claim 5, wherein the sterically hindered phenolic antioxidant has the general structure (VI).

7. The fiber-reinforced polymer composition according to claim 6, wherein the sterically hindered phenolic antioxidant comprises tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate.

8. The fiber-reinforced polymer composition according to claim 1, wherein the phosphite antioxidant is present in the composition in an amount of 0.02 to 2% by weight.

9. The phosphite antioxidant is of the following general structure (IX): [Chemical Formula 3] (In the formula, R １ 、 R ２ 、 R ３ 、 R ４ 、 R ５ 、 R ６ 、 R ７ 、 R ８ 、 R ９ 、 and R １０ are, independently, hydrogen, C １ ~ C １０ alkyl, and C ３ ~ C ３０ branched alkyl (selected from) The fiber-reinforced polymer composition according to claim 1, which is an aryldiphosphite having

10. The fiber-reinforced polymer composition according to claim 9, wherein the aryldiphosphite comprises bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, or a combination thereof.

11. The fiber-reinforced polymer composition according to claim 1, wherein the thioester antioxidant is present in the composition in an amount of 0.04 to 4% by weight.

12. The thioester antioxidant has the following general structure: R １１ -OC(O)(CH ２ ) ｘ -S-(CH ２ ) ｙ C(O)O-R １２ (In the formula, x and y are independently 1 to 10; R １１ and R １２ are each independently selected from linear or branched C ６ -C ３０ alkyl). The fiber-reinforced polymer composition according to claim 1, which is a thiocarboxylic acid ester having

13. The fiber-reinforced polymer composition according to claim 12, wherein the thiocarboxylic acid ester is distearyl thiodipropionate, dilauryl thiodipropionate, di-2-ethylhexyl-thiodipropionate, diisodecyl thiodipropionate, or a combination thereof.

14. The fiber-reinforced polymer composition according to claim 1, wherein the polymer matrix comprises a propylene homopolymer, a propylene / α-olefin copolymer, or a combination thereof.

15. The fiber-reinforced polymer composition according to claim 1, wherein the fiber-reinforced composition comprises 0.1% to 15% by weight of a compatibilizer.

16. The fiber-reinforced polymer composition according to claim 15, wherein the compatibilizer comprises a polyolefin modified with a polar functional group.

17. The fiber-reinforced composition according to claim 1, wherein the fiber is a glass fiber.

18. The fiber-reinforced polymer composition according to claim 1, wherein the fiber is oriented in the longitudinal direction of the composition.

19. A molded part comprising the fiber-reinforced composition according to claim 1.

20. The molded part according to claim 19, which is injection molded.

21. The molded part according to claim 19, which has a wall thickness of 2.5 millimeters or less.

22. An automotive part comprising the fiber-reinforced composition according to claim 1.

23. A stabilizer system for use in a fiber-reinforced polymer composition, wherein the stabilizer system comprises a sterically hindered phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant, and the weight ratio of the phosphite antioxidant to the sterically hindered phenolic antioxidant in the system is from 1:1 to 5:1, the weight ratio of the thioester antioxidant to the sterically hindered phenolic antioxidant in the system is from 2:1 to 10:1, and the weight ratio of the thioester antioxidant to the phosphite antioxidant is from 1:1 to 5:1 and the stabilizer system does not contain any of 3-(N-salicyloyl)amino-1,2,4-triazole, 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide, and 2,2'-oxamidobis[ethyl 3-(3,5-tert-butyl-4-hydroxyphenyl)propionate], said stabilizer system.

24. The stabilizer system according to claim 23, wherein the sterically hindered phenolic antioxidant is present in the composition in an amount of 0.01 to 1% by weight.

25. The sterically hindered phenolic antioxidant has one of the following general structures (IV), (V), and (VI): [Chemical Formula 4] (wherein, a, b, and c are independently in the range of 1 to 10; R ８ 、R ９ 、R １０ 、R １１ 、and R １２ are, independently, hydrogen, C １ - C １０ alkyl, and C ３ - C ３０ branched alkyl; R １３ , R １４ , and R １５ are, independently, the following general structures (VII) and (VIII): 【Chemical Formula 5】 wherein, d is in the range of 1 to 10; R １６ 、 R １７ 、 R １８ 、 and R １９ are, independently, hydrogen, C １ -C １０ alkyl, and C ３ -C ３０ (selected from branched alkyl)) selected from the groups represented by one of) The stabilizer system according to claim 23, having one of them.

26. The stabilizer system according to claim 25, wherein the sterically hindered phenolic antioxidant has the general structure (VI).

27. The stabilizer system according to claim 26, wherein the sterically hindered phenolic antioxidant contains tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate.

28. The stabilizer system according to claim 23, wherein the phosphite antioxidant is present in the composition in an amount of 0.02 to 2% by weight.

29. The phosphite antioxidant has the following general structure (IX): 【Chemical Formula 6】 wherein, R １ 、 R ２ 、 R ３ 、 R ４ 、 R ５ 、 R ６ 、 R ７ 、 R ８ 、 R ９ 、 and R １０ are, independently, hydrogen, C １ - C １０ alkyl, and C ３ - C ３０ branched alkyl (selected from). The stabilizer system according to claim 23, which is an aryldiphosphite having.

30. The stabilizer system according to claim 29, wherein the aryldiphosphite contains bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, or a combination thereof.

31. The stabilizer system according to claim 23, wherein the thioester antioxidant is present in the composition in an amount of 0.04 to 4% by weight.

32. The thioester antioxidant has the following general structure: R １１ -OC(O)(CH ２ ) ｘ -S-(CH ２ ) ｙ C(O)O-R １２ (wherein x and y are independently 1 to 10; R １１ and R １２ are each independently selected from linear or branched C ６ -C ３０ alkyl). The stabilizer system according to claim 23, which is a thiocarboxylic acid ester having

33. The stabilizer system according to claim 32, wherein the thiocarboxylic acid ester is distearyl thiodipropionate, dilauryl thiodipropionate, di-2-ethylhexyl-thiodipropionate, diisodecyl thiodipropionate, or a combination thereof.

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