Rack and pinion housing element of a vehicle, manufactured using a composition with excellent dimensional stability

Abstract

Rack housing element of a vehicle, formed from a composition for a rack housing element of a vehicle, the composition comprising: 100 parts by weight of a base resin containing polybutylene terephthalate, an acrylonitrile-styrene-acrylate copolymer, and polyethylene terephthalate; and 40 to 75 parts by weight of an inorganic filler; wherein the inorganic filler contains a glass fiber and a platelet-shaped mineral filler.

Description

Background area

[0001] Exemplary embodiments of the present disclosure relate to a rack housing member of a vehicle formed from a composition having excellent dimensional stability. Discussion of the background

[0002] A vehicle's power steering system is a motor-driven power steering device that uses hydraulic pressure from a hydraulic pump driven by an engine, allowing the vehicle to be steered with minimal steering effort. The power steering system assists the driver's steering by transmitting the power of an electric motor as auxiliary torque, which assists steering torque, to a steering shaft through a reduction gear mechanism when the steering torque is output to a steering shaft via a steering wheel. For example, when the driver operates the steering wheel, the torque applied to the steering shaft is output to a detection sensor, such as a rack-and-pinion torque sensor, and controlled by a control device.

[0003] A cover for such a torque sensor was manufactured using a thermoplastic resin, such as a polyester-based resin, and a glass fiber. Polyester-based resin is an engineering plastic with excellent mechanical and electrical properties, as well as physical and chemical properties, and is applied to a wide range of fields, such as vehicles, electrical and electronic equipment, and office machines. However, thermoplastic resins, such as polyester-based resins, are disadvantageous in terms of dimensional stability due to their large thermal expansion and contraction compared to metal. Thus, airtightness deteriorates due to post-deformation in a component connection part, etc., caused by heat in a high-temperature environment, which causes leakage in an assembled component.

[0004] Prior art documents related to the present disclosure include Korean Laid-Open Patent Application No. 2014-0092471 (published on July 24, 2014, entitled “Polyester Composition”).

[0005] US 2011 / 0144239 A1 discloses a glass fiber reinforced polyester resin composition and a molded product made using the same.

[0006] US 2008 / 0076859 A1 discloses thermoplastic polyester molding compounds which have good flowability and, at the same time, good mechanical properties.

[0007] US 6,689,838 B1 concerns reduced-adhesion molding compounds for automotive applications. Short description

[0008] An object of the present disclosure is to provide a composition for a rack housing member of a vehicle having excellent dimensional stability and an excellent effect of improving warpage during injection molding.

[0009] Another object of the present disclosure is to provide a composition for a rack housing member of a vehicle having excellent rigidity, durability and chemical resistance.

[0010] Yet another object of the present disclosure is to provide a composition for a rack housing member of a vehicle having excellent injection moldability, productivity and economy.

[0011] Yet another object of the present disclosure is to provide a method of manufacturing the composition for a rack housing member of a vehicle.

[0012] Yet another object of the present disclosure is to provide a rack housing member of a vehicle manufactured using the composition for a rack housing member of a vehicle.

[0013] One aspect of the present disclosure relates to a composition for a rack housing member of a vehicle, from which the rack housing member of a vehicle according to the invention is formed. The composition for a rack housing member of a vehicle comprises 100 parts by weight of a base resin containing polybutylene terephthalate, an acrylonitrile-styrene-acrylate copolymer, and polyethylene terephthalate; and 40 to 75 parts by weight of an inorganic filler, wherein the inorganic filler contains a glass fiber and a plate-shaped mineral filler.

[0014] In one embodiment, the base resin may contain 55 to 65 parts by weight of polybutylene terephthalate, 25 to 35 parts by weight of an acrylonitrile-styrene-acrylate copolymer, and 8 to 15 parts by weight of polyethylene terephthalate.

[0015] In one embodiment, the polybutylene terephthalate may have an intrinsic viscosity of 0.5 to 1.4 dl / g, and the polyethylene terephthalate may have an intrinsic viscosity of 0.5 to 1.2 dl / g.

[0016] In one embodiment, the acrylonitrile-styrene-acrylate copolymer may comprise 20 to 60 parts by weight of acrylate rubber.

[0017] In one embodiment, the glass fiber may be contained in an amount of 35 to 50 parts by weight, and the platelet-shaped mineral filler may be contained in an amount of 5 to 20 parts by weight, based on 100 parts by weight of the base resin.

[0018] In one embodiment, the inorganic filler may comprise the platelet-shaped mineral filler and the glass fiber in a weight ratio of 1:1.2 to 1:4.

[0019] In one embodiment, the glass fiber may have a nominal diameter of 3 to 15 µm and an average length of 0.05 to 5 mm.

[0020] In one embodiment, the platelet-shaped mineral filler may comprise one or more of wollastonite, talc, and mica.

[0021] In one embodiment, the platelet-shaped mineral filler may have a cross-sectional axis ratio (long diameter of the cross section / short diameter of the cross section) of 3 to 50 and a length of 0.01 to 5 mm.

[0022] In one embodiment, the composition for a rack housing member of a vehicle may have a tensile strength of 1100 to 1600 kgf / cm 2and have a flexural strength of 1800 to 2500 MPa measured according to ASTM D 790.

[0023] In one embodiment, the composition for a rack housing member of a vehicle may have a shrinkage in the machine direction (MD) in the following equation 1 of 0.6% or less and a shrinkage in the transverse direction (TD) in the following equation 2 of 1.2% or less after injection molding: MD shrinkage(%)=((A1−A0) / A0)×100, wherein, for a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thick, A0 is an MD length (mm) measured immediately after injection molding of the test specimen, and A1 is an MD length (mm) measured after allowing the test specimen to stand for 24 hours at 25 °C. TD−Shrinkage(%)=((B1−B0) / B0)×100, wherein, for a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thick, B0 is a TD length (mm) measured immediately after injection molding of the test specimen, and B1 is a TD length (mm) measured after allowing the test specimen to stand for 24 hours at 25 °C.

[0024] In one embodiment, the TD shrinkage and the MD shrinkage may have a relationship according to the following equation 3: |TD−Shrinkage(%)−MD−Shrinkage(%)|≤0.6.

[0025] In one embodiment, the warpage value measured for a test piece obtained by injection molding the composition for a rack housing member of a vehicle into a multi-stage mold of 100 mm width x 150 mm depth x 1.7 mm-2.1 mm-3.0 mm thickness may be 4 mm or less.

[0026] The subject matter of the invention relates to a rack housing member of a vehicle formed from the composition for a rack housing member of a vehicle.

[0027] In one embodiment, the rack housing member of a vehicle may comprise a torque sensor cover of a rack housing of a vehicle.

[0028] A composition for a rack housing member of a vehicle according to the present disclosure can have excellent dimensional stability, an excellent effect of improving warpage during injection molding, as well as excellent rigidity, durability, chemical resistance, injection moldability, productivity, and economy, and can be suitable for use in applications such as a torque sensor cover of a rack housing of a vehicle. Short description of the characters Fig.1 illustrates a vehicle steering apparatus according to an embodiment of the present disclosure. Fig. 2 illustrates a torque sensor cover according to an embodiment of the present disclosure. Detailed description of the illustrated embodiments

[0029] In the following, a composition for a rack housing member of a vehicle having excellent dimensional stability and a rack housing member of a vehicle manufactured using the same will be described with reference to various exemplary embodiments.

[0030] Although exemplary embodiments of the disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the disclosure as defined in the appended claims. Thus, the true technical scope of the disclosure should be defined by the following claims.

[0031] In the following description, the detailed description of the related known technology or configuration is omitted if it may detract from the subject matter of the present disclosure.

[0032] Furthermore, the terms for constituent elements described below are defined in consideration of their functions in the present disclosure and may be changed according to the intention of a user or operator or according to custom. Accordingly, definitions of these terms must be based on the present overall description. Composition for rack housing element of a vehicle

[0033] One aspect of the present disclosure relates to a composition for a rack housing member of a vehicle from which the rack housing member of a vehicle according to the invention is formed. The composition for a rack housing member of a vehicle comprises 100 parts by weight of a base resin containing polybutylene terephthalate, an acrylonitrile-styrene-acrylate copolymer, and polyethylene terephthalate; and 40 to 75 parts by weight of an inorganic filler, wherein the inorganic filler comprises a glass fiber and a plate-shaped mineral filler.

[0034] The composition for a rack housing element of a vehicle is described in more detail below. Base resin

[0035] The base resin contains polybutylene terephthalate, an acrylonitrile-styrene-acrylate copolymer, and polyethylene terephthalate. In one embodiment, the base resin may contain 55 to 65 parts by weight of polybutylene terephthalate, 25 to 35 parts by weight of an acrylonitrile-styrene-acrylate copolymer, and 8 to 15 parts by weight of polyethylene terephthalate. Polybutylene terephthalate

[0036] "Polybutylene terephthalate" (PBT) refers to a polybutylene terephthalate homopolymer and a polybutylene terephthalate copolymer.

[0037] In one embodiment, the polybutylene terephthalate can be prepared by condensation polymerization via the direct esterification or transesterification of 1,4-butanediol and terephthalic acid or dimethyl terephthalate.

[0038] In one embodiment, the polybutylene terephthalate may have a weight-average molecular weight of 5,000 to 300,000 g / mol. The composition of the present disclosure may exhibit excellent mechanical strength under the above conditions.

[0039] In one embodiment, the weight average molecular weight of the polybutylene terephthalate can be measured by a conventional measuring method.

[0040] The weight average molecular weight of polybutylene terephthalate is determined, for example, by gel permeation chromatography (GPC) using a polymethyl methacrylate (PMMA) standard and a solvent such as hexafluoroisopropanol, trifluoroethanol, and the like.

[0041] In one embodiment, the polybutylene terephthalate may have an intrinsic viscosity of 0.5 dl / g to 1.4 dl / g. The composition may exhibit excellent miscibility, impact resistance, dimensional stability, and appearance characteristics under the above conditions. In one embodiment, the intrinsic viscosity (IV) of the polybutylene terephthalate resin may be measured at 35°C using an o-chlorophenol solution (concentration: 0.01 g / ml). For example, the polybutylene terephthalate may have an intrinsic viscosity of 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, or 1.4 dl / g.

[0042] In one embodiment, the polybutylene terephthalate may be contained in an amount of 55 to 65 parts by weight based on the total weight of the base resin. When the polybutylene terephthalate is contained within the above range, the composition can exhibit excellent flowability and moldability, and the vehicle rack housing member produced therefrom can exhibit excellent smoothness, dimensional stability, and mechanical strength. For example, the polybutylene terephthalate may be contained in an amount of 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, or 65 parts by weight based on the total weight of the base resin. Acrylonitrile-styrene-acrylate copolymer

[0043] The acrylonitrile-styrene-acrylate (ASA) copolymer may be amorphous, and it may also be a graft copolymer having a core-shell structure comprising a shell layer formed by graft copolymerizing a styrene monomer and an acrylonitrile monomer on a rubbery acrylate polymer core.

[0044] In one embodiment, the acrylonitrile-styrene-acrylate copolymer may comprise 20 to 60 parts by weight of acrylate rubber. When the acrylate rubber is included in the above content, the composition can exhibit excellent heat resistance, weather resistance, and impact resistance.

[0045] For example, the acrylonitrile-styrene-acrylate copolymer may comprise 20 to 60 parts by weight of a rubbery acrylate polymer core and 40 to 80 parts by weight of a shell layer formed by graft copolymerizing a styrene monomer and an acrylonitrile monomer. The graft copolymerization can be carried out using a conventional manufacturing process. For example, the graft copolymerization can be carried out using emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization, among others.

[0046] In one embodiment, the acrylonitrile-styrene-acrylate copolymer may be contained in an amount of 25 to 35 parts by weight based on the total weight of the base resin. When the polybutylene terephthalate is contained within the above range, the cooling time during injection molding can be shortened, and the rack housing member of a vehicle can thus exhibit excellent productivity, dimensional stability, and mechanical strength. For example, the acrylonitrile-styrene-acrylate copolymer may be contained in an amount of 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35 parts by weight based on the total weight of the base resin. Polyethylene terephthalate

[0047] Polyethylene terephthalate (PET) can be produced by condensation polymerization via direct esterification or transesterification of terephthalic acid or dimethyl terephthalate as a monomer.

[0048] When the polyethylene terephthalate is included, the cooling time during injection molding of the component can be shortened by slightly adjusting the crystallization rate of the base resin, and the rack housing member of a vehicle can thus have excellent productivity, strength, and dimensional stability.

[0049] In one embodiment, the polyethylene terephthalate may have a weight-average molecular weight of 5,000 to 300,000 g / mol. The composition of the present disclosure may exhibit excellent mechanical strength under the above conditions.

[0050] In one embodiment, the weight average molecular weight of the polyethylene terephthalate can be measured by a conventional measuring method.

[0051] The weight average molecular weight of polyethylene terephthalate is determined, for example, by gel permeation chromatography (GPC) using a polymethyl methacrylate (PMMA) standard and a solvent such as hexafluoroisopropanol, trifluoroethanol, and the like.

[0052] In one embodiment, the polyethylene terephthalate may have an intrinsic viscosity of 0.5 to 1.2 dl / g. The composition may exhibit excellent miscibility, impact resistance, dimensional stability, and appearance characteristics under the above conditions. In one embodiment, the intrinsic viscosity (IV) of the polyethylene terephthalate resin may be measured at 35°C using an o-chlorophenol solution (concentration: 0.01 g / ml). For example, the polyethylene terephthalate may have an intrinsic viscosity of 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2 dl / g.

[0053] In one embodiment, the polyethylene terephthalate may be contained in an amount of 8 to 15 parts by weight based on the total weight of the base resin. When the polyethylene terephthalate is contained in the above content, the cooling time during component injection molding can be shortened, and the rack housing member of a vehicle according to the present disclosure can thus exhibit excellent productivity, strength, and dimensional stability. For example, the polyethylene terephthalate may be contained in an amount of 8, 9, 10, 11, 12, 13, 14, or 15 parts by weight based on the total weight of the base resin.

[0054] Meanwhile, in the method for producing the base resin, in a case where alloying is carried out by adding the acrylonitrile-styrene-acrylate copolymer, which is an amorphous resin, in excess of a crystalline resin, the cooling time in a molding process of the component may increase excessively, so that the process cycle time may be exceptionally increased.

[0055] In one embodiment, the base resin may comprise polyethylene terephthalate, acrylonitrile-styrene-acrylate copolymer, and polybutylene terephthalate in a weight ratio of 1:2 to 5:2 to 7. When the polyethylene terephthalate, acrylonitrile-styrene-acrylate copolymer, and polybutylene terephthalate are contained within the above weight range, the miscibility and dispersibility of the composition can be excellent, the cooling time during injection molding can be shortened, and the rack housing member of a vehicle can thus exhibit excellent productivity, strength, and dimensional stability. For example, the above-mentioned compounds may be contained in a weight ratio of 1:2 to 4:3 to 7.

[0056] Thus, the present disclosure can suppress high crystallization of polybutylene terephthalate by using polybutylene terephthalate having a high crystallization rate, an acrylonitrile-styrene-acrylate copolymer, and polyethylene terephthalate having a relatively low crystallization rate in an optimal amount, and can improve dimensional stability while maintaining rigidity by replacing some of the glass fibers that may cause warpage of a product measured by Poisson's ratio with a plate-like mineral filler. Inorganic filler

[0057] The inorganic filler comprises a glass fiber and a platelet-shaped mineral filler.

[0058] In one embodiment, the glass fiber may have a circular or elliptical cross-section. In one embodiment, the glass fiber may have an average diameter of 3 to 15 µm and an average length (cut length) of 0.05 to 5 mm. The composition for a steering rack housing member of a vehicle may exhibit excellent miscibility, formability, dimensional stability, and mechanical strength under the above conditions.

[0059] In one embodiment, the glass fiber may be contained in an amount of 35 to 50 parts by weight based on 100 parts by weight of the base resin. When the glass fiber is contained within the above range, the composition can exhibit excellent miscibility, dispersibility, and mechanical strength.

[0060] For example, the glass fiber may be contained in an amount of 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 parts by weight based on 100 parts by weight of the base resin.

[0061] The platelet-shaped mineral filler is included to improve dimensional stability and prevent the occurrence of warpage due to a difference in shrinkage in a vertical direction (i.e., a TD) versus a flow direction (i.e., an MD) by orienting the glass fibers in the flow direction during injection molding of the composition of the present disclosure.

[0062] In one embodiment, the platelet-shaped mineral filler may comprise one or more of wollastonite, talc, and mica. For example, the platelet-shaped mineral filler may comprise talc. When the platelet-shaped mineral filler comprises the above-mentioned components, the composition may exhibit excellent mechanical properties, such as stiffness, and an excellent effect in improving dimensional stability.

[0063] In one embodiment, the platelet-shaped mineral filler may have a cross-sectional axial ratio (long cross-sectional diameter / short cross-sectional diameter) of 3 to 50 and a length of 0.01 to 5 mm. The composition may exhibit excellent miscibility and formability under the above conditions, as well as an excellent effect in improving dimensional stability.

[0064] In one embodiment, the plate-shaped mineral filler may be contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the base resin. When the plate-shaped mineral filler is contained in the above content, deterioration of the mechanical properties of the composition can be prevented and the anisotropy of the glass fiber can be suppressed, resulting in an excellent effect of improving dimensional stability. For example, the plate-shaped mineral filler may be contained in an amount of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by weight based on 100 parts by weight of the base resin.

[0065] In one embodiment, the inorganic filler may comprise the plate-shaped mineral filler and the glass fiber in a weight ratio of 1:1.2 to 1:4. When the plate-shaped mineral filler and the glass fiber are contained in the above weight ratio, the composition can exhibit excellent rigidity and formability, and the anisotropy of the glass fiber can be suppressed, resulting in an excellent effect of improving dimensional stability. For example, the inorganic filler may comprise the plate-shaped mineral filler and the glass fiber in a weight ratio of 1:1.8 to 1:3.

[0066] The inorganic filler is contained in an amount of 40 to 75 parts by weight based on 100 parts by weight of the base resin. If the inorganic filler is contained in an amount of less than 40 parts by weight, mechanical properties such as rigidity may deteriorate, and if the inorganic filler is contained in an amount exceeding 75 parts by weight, dimensional stability may deteriorate and warpage may increase. For example, the inorganic filler may be contained in an amount of 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74 or 75 parts by weight based on 100 parts by weight of the base resin. Additive

[0067] In one embodiment, the composition for a rack housing member of a vehicle may further comprise 0.01 to 30 parts by weight of an additive, based on 100 parts by weight of the base resin. In one embodiment, the additive may comprise, among others, one or more of a thermal stabilizer, an antioxidant, a light stabilizer, a release agent, a compatibilizer, a dye, a pigment, a colorant, a plasticizer, an impact modifier, a stabilizer, and a lubricant.

[0068] In one embodiment, the composition for a rack housing member of a vehicle may have a tensile strength of 1100 to 1600 kgf / cm 2 and a flexural strength of 1800 to 2500 kgf / cm measured according to ASTM D 790 2For example, the composition for a rack housing member of a vehicle may have a tensile strength of 1250 to 1400 kgf / cm 2 and a bending strength of 1950 to 2200 kgf / cm 2 have.

[0069] In one embodiment, the composition for a rack housing member of a vehicle may have a shrinkage in the machine direction (MD) in the following equation 1 of 0.6% or less and a shrinkage in the transverse direction (TD) in the following equation 2 of 1.2% or less after injection molding: MD shrinkage(%)=((A1−A0) / A0)×100, wherein, for a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thick, A0 is an MD length (mm) measured immediately after injection molding of the test specimen, and A1 is an MD length (mm) measured after allowing the test specimen to stand for 24 hours at 25 °C. TD−Shrinkage(%)=((B1−B0) / B0)×100, wherein, for a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thick, B0 is a TD length (mm) measured immediately after injection molding of the test specimen, and B1 is a TD length (mm) measured after allowing the test specimen to stand for 24 hours at 25 °C.

[0070] In one embodiment, the TD shrinkage and MD shrinkage may be values ​​measured using an electric injection molding machine (SE75EV-C110) with a screw diameter of 22 mm available from Sumitomo Corporation.

[0071] In one embodiment, the TD shrinkage and the MD shrinkage may have a relationship according to the following equation 3: |TD−Shrinkage(%)−MD−Shrinkage(%)|≤0.6.

[0072] Under the above conditions, the rack housing member can exhibit minimized warpage and excellent dimensional stability. For example, the value of Equation 3 can be 0.5 or less. For example, the value of Equation 3 can be 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6.

[0073] In one embodiment, a warpage value measured for a test specimen obtained by injection molding the composition for a vehicle rack housing member into a multi-stage mold measuring 100 mm wide x 150 mm deep x 1.7 mm-2.1 mm-3.0 mm thick may be 4 mm or less. For example, the warpage value may be 2.5 mm or less.

[0074] For example, the warpage value may be a value measured using a hydraulic injection molding machine (LGH100DGC) available from LS Electric with a screw diameter of 36 mm.

[0075] In one embodiment, the composition for a rack housing member of a vehicle can be prepared by preparing a granular composition by premixing the components having the above-mentioned contents using various mixers, and then melting and kneading the premixed components using a Banbury mixer, a roller, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader, and then using the granular composition for injection molding.For example, the composition for a rack housing member of a vehicle can be produced by preparing a granular composition for a rack housing member of a vehicle by introducing the components of the composition for a rack housing member of a vehicle into a twin-screw extruder, melting and kneading the introduced components, and extruding the resulting components at an extrusion temperature of 200 to 300 °C, and then using the granular composition for injection molding.

[0076] The composition for a rack housing member of a vehicle according to the present disclosure can have excellent dimensional stability, an excellent effect of improving warpage during injection molding, as well as excellent rigidity, durability, chemical resistance, injection moldability, productivity, and economy, and can be suitable for use in applications such as a torque sensor cover of a rack housing of a vehicle. Rack housing element of a vehicle, characterized in that it is formed from the composition for a rack housing element of a vehicle

[0077] The present invention relates to a rack housing member of a vehicle formed from the composition for a rack housing member of a vehicle.

[0078] In one embodiment, the rack housing member of a vehicle may comprise a torque sensor cover of a rack housing of a vehicle.

[0079] Fig. 1 illustrates a vehicle steering apparatus 100 according to an embodiment of the present disclosure, and Fig. 2 shows a torque sensor cover 50 according to an embodiment of the present disclosure.

[0080] Referring to Fig.1, the vehicle steering device 100 may include a steering wheel 10, a steering shaft 20, a rack housing 30, and tie rods 40. The steering wheel 10 is arranged in front of the driver's seat. The steering shaft 20 is connected to the steering wheel 10. The rack housing 30 includes a rack drive shaft 32 extending in the transverse direction of a vehicle and meshing with the steering shaft 20. The rack drive shaft 32 converts the rotational force input from the steering shaft 20 into linear motion. The tie rods 40 are arranged on both sides of the rack housing 30 so as to be connected to a steering knuckle (not shown) of a wheel. A pinion gear 22 may be provided below the steering shaft 20, which meshes with the rack drive shaft 32.

[0081] In one embodiment, a torque sensor (not shown) is provided on a side surface of the rack housing 30. The torque sensor is connected to the steering shaft 20 to measure the torque applied to the steering shaft 20. The torque sensor may be disposed within the torque sensor cover 50.

[0082] In one embodiment, the torque sensor cover 50 may be formed from a composition for a rack housing member of a vehicle.

[0083] Unless otherwise stated, all standards referenced herein, such as ASTM, ISO, etc., are the current versions of the respective standard as of the day before the priority date.

[0084] Hereinafter, the configuration and operation of the present disclosure will be described in more detail with reference to preferred examples of the present disclosure. These examples are presented merely as preferred examples of the present disclosure and should not be considered limiting the present disclosure in any way. Examples and comparison examples

[0085] The components used in the following examples and comparative examples are as follows. (A) Base resin

[0086] (A1) A polybutylene terephthalate resin with an intrinsic viscosity of 0.5 to 1.4 dl / g was used. (A2) An acrylonitrile-styrene-acrylate copolymer containing 20 to 60 parts by weight of acrylate rubber was used. (A3) A polyethylene terephthalate resin with an intrinsic viscosity of 0.5 to 1.2 dl / g was used. (B) Inorganic filler

[0087] (B1) A glass fiber with a nominal diameter of 3 to 15 µm and an average length of 0.05 to 5 mm was used. (B2) Talc was used as the mineral filler, which had a platelet-shaped cross-section, a cross-sectional axis ratio (long cross-section diameter / short cross-section diameter) of 3 to 50, and a length of 0.01 to 5 mm. Examples 1 to 3 and Comparative Examples 1 to 6

[0088] Each of the above components was added in an amount shown in Table 1 below, and the added components were extruded using a twin-screw extruder under conditions of a screw rotation speed of 150 to 250 rpm at a cylinder temperature of 200 to 260°C, thereby preparing a granular composition for a rack housing member of a vehicle. The prepared granules were dried under conditions of an injection temperature of 250 to 330°C and charged into an injection molding machine, thereby preparing test specimens.

[0089] For Examples 1 to 3 and Comparative Examples 1 to 6, the physical properties of each specimen were evaluated in the following manner, and the evaluation results are shown in Table 1 below. (1) MD shrinkage (%) and TD shrinkage (%): Injection molding was performed in a mold measuring 60 mm in a resin flow direction (i.e., MD) x 60 mm in a vertical direction (i.e., TD) against the flow direction x 2 mm thick, using an electric injection molding machine (SE75EV-C110) available from Sumitomo Corporation with a screw diameter of 22 mm. For each of the test specimens of Examples and Comparative Examples obtained by injection molding as described above, MD shrinkage and TD shrinkage were measured according to the following Equations 1 and 2, and the difference in shrinkage was calculated according to the following Equations 3: MD shrinkage(%)=((A1−A0) / A0)×100, where A0 is an MD length (mm) measured immediately after injection molding of the specimen and A1 is an MD length (mm) measured after the specimen has been left standing for 24 hours at 25 °C. TD−Shrinkage(%)=((B1−B0) / B0)×100, where B0 is a TD length (mm) measured immediately after injection molding of the specimen and B1 is a TD length (mm) measured after the specimen has been left standing for 24 hours at 25 °C. |TD−Shrinkage(%)−MD−Shrinkage(%)|

[0090] (2) Warpage (mm): Warpage was measured for each of the test specimens of Examples and Comparative Examples obtained by injection molding the composition into a multi-stage mold measuring 100 mm wide x 150 mm deep x 1.7 mm-2.1 mm-3.0 mm thick using a hydraulic injection molding machine (LGH100DGC) available from LS Electric with a screw diameter of 36 mm. Warpage occurred in the left part of an injection port of the injection molding machine and was evaluated based on its highest measured value.

[0091] (3) Tensile strength (kgf / cm 2 ) and flexural strength (kgf / cm 2): Tensile strength was measured in accordance with ASTM D 638 and flexural strength was measured in accordance with ASTM D 790.

[0092] (4) Cooling time (s): The cooling time was measured for the specimens of the examples and comparative examples during injection molding in item (1) above. When the cooling time during injection molding is short, the injected specimen does not move to the movable side of the mold and is fixed to the fixed side. The injected specimen fixed to the fixed side is detached only by the operator's intention. When the cooling time is sufficient, an injected product is removed from the movable side by an ejector pin, allowing normal operation. Table 1 Classification (parts by weight) Examples Comparison examples 1 2 3 1 2 3 4 5 6 (A1) 60 55 55 100 60 70 60 60 60 (A2) 30 31 35 - 40 30 30 30 30 (A3) 10 14 10 - - - 10 10 10 (B1) 50 50 45 43 50 50 43 20 45 (B2) 17 17 20 - 17 17 - 10 35 MD shrinkage (%) 0,58 0,53 0,55 0,59 0,52 0,55 0,55 0,69 0,50 TD shrinkage (%) 1,01 1,13 1,11 1,56 0,93 1,00 1,15 1,73 0,92 |TD shrinkage - MD shrinkage| 0,43 0,60 0,56 0,47 0,41 0,45 0,60 1,04 0,42 Warpage (mm) 2,49 3,77 4,47 8,20 1,98 2,05 5,07 4,25 2,07 Tensile strength (kgf / cm 2 ) 1360 1330 1320 1380 1150 1220 1360 950 1180 Flexural strength (kgf / cm 2 ) 2060 2120 2050 2300 1890 1990 2060 1510 1830 Cooling time (s) 5,0 5,4 5,2 3,6 7,3 5,8 5,4 5,8 5,2

[0093] From the result in Table 1, it was found that in the case of Examples 1 to 3 of the present disclosure, the injection cooling time was shortened, resulting in excellent productivity, the MD shrinkage was 0.6% or less, and the TD shrinkage was 1.2% or less, resulting in excellent dimensional stability. On the other hand, it was found that in the case of Comparative Examples 1 to 6 outside the scope of the present disclosure, the MD shrinkage, the TD shrinkage, or the warpage was increased compared to Examples 1 to 3, resulting in a reduction in dimensional stability, or the cooling time in the injection process was increased, resulting in a reduction in productivity.

[0094] Simple modifications or changes to the present disclosure can be easily made by those skilled in the art, and all such modifications or changes should be considered to be included within the scope of the present disclosure.

Claims

[1] A rack housing member of a vehicle formed from a composition for a rack housing member of a vehicle, the composition comprising: 100 parts by weight of a base resin containing polybutylene terephthalate, an acrylonitrile-styrene-acrylate copolymer and polyethylene terephthalate; and 40 to 75 parts by weight of an inorganic filler; wherein the inorganic filler contains a glass fiber and a platelet-shaped mineral filler. [2] The rack housing member according to claim 1, wherein the base resin contains 55 to 65 parts by weight of polybutylene terephthalate, 25 to 35 parts by weight of an acrylonitrile-styrene-acrylate copolymer, and 8 to 15 parts by weight of polyethylene terephthalate. [3] The rack housing member according to claim 1, wherein the polybutylene terephthalate has an intrinsic viscosity of 0.5 to 1.4 dl / g and the polyethylene terephthalate has an intrinsic viscosity of 0.5 to 1.2 dl / g. [4] A rack housing member according to claim 1, wherein the acrylonitrile-styrene-acrylate copolymer comprises 20 to 60 parts by weight of acrylate rubber. [5] The rack housing member according to claim 1, wherein the glass fiber is contained in an amount of 35 to 50 parts by weight and the plate-shaped mineral filler is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the base resin. [6] The rack housing member according to claim 5, wherein the inorganic filler comprises the plate-shaped mineral filler and the glass fiber in a weight ratio of 1:1.2 to 1:

4. [7] A rack housing member according to claim 1, wherein the glass fiber has a nominal diameter of 3 to 15 µm and an average length of 0.05 to 5 mm. [8] A rack housing member according to claim 1, wherein the platelet-shaped mineral filler comprises one or more of wollastonite, talc and mica. [9] The rack housing member according to claim 1, wherein the plate-shaped mineral filler has a cross-sectional axis ratio (long diameter of the cross section / short diameter of the cross section) of 3 to 50 and a length of 0.01 to 5 mm. [10] A rack housing member according to claim 1, wherein the composition has a tensile strength of 1100 to 1600 kgf / cm measured according to ASTM D 638 2 and a flexural strength of 1800 to 2500 kgf / cm measured according to ASTM D 790 2 has. [11] The rack housing member according to claim 1, wherein the composition after injection molding has a shrinkage in the machine direction (MD) in the following equation 1 of 0.6% or less and a shrinkage in the transverse direction (TD) in the following equation 2 of 1.2% or less: MD shrinkage(%)=((A1−A0) / A0)×100, wherein, in a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thickness, A0 is an MD length (mm) measured immediately after injection molding of the specimen and A1 is an MD length (mm) measured after the specimen has been left standing for 24 hours at 25 °C; and TD−Shrinkage(%)=((B1−B0) / B0)×100, wherein, in a test specimen obtained by injection molding the composition for a rack housing member of a vehicle into a mold of 60 mm MD x 60 mm TD x 2 mm thickness, B0 is a TD length (mm) measured immediately after injection molding of the test specimen and B1 is a TD length (mm) measured after the specimen has been left standing for 24 hours at 25 °C. [12] A rack housing member according to claim 11, wherein the TD shrinkage and the MD shrinkage have a relationship according to the following equation 3: |TD−Shrinkage(%)−MD−Shrinkage(%)|≤0.

6. [13] The rack housing member according to claim 1, wherein the warpage value measured on a test piece obtained by injection molding the composition into a multi-stage mold of 100 mm width x 150 mm depth x 1.7 mm-2.1 mm-3.0 mm thickness is 4 mm or less. [14] A rack housing member according to any preceding claim, wherein the rack housing member of a vehicle comprises a torque sensor cover of a rack housing of a vehicle.

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