JPH06170882A - Steering wheel and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a steering wheel, provided with soft feeling upon gripping, improved in handling operability and reduced in the weight thereof. CONSTITUTION:A steering wheel is constituted of a metallic core 2, inserted into the inner part thereof and having the diameter of 4-8mm, a surface layer 4, constituted of thermoplastic olefin or styrene elastomer, and a propylene resin layer 3, blended with inorganic filler to regulate the modulus of elasticity (JIS-K7203) so as to be 70,000-170,000kg/cm<2> and having the thickness of 3-10mm, and interposed between the metallic core and the surface layer 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention provides a soft feel,
The present invention relates to a lightweight steering wheel with improved handle operability and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in a steering wheel, a metal core having an inserted diameter of 9 to 10 mm is surrounded by polypropylene (PP), polyvinyl chloride (PVC), and polyurethane foam (urethane integral skin foam).
Those coated with a relatively hard synthetic resin material, such as, have been used. However, in recent years, a soft steering wheel has been demanded from the viewpoints of safety, improvement in feel when grasped, and improvement in operability. In addition, the weight reduction of steering wheels has been attracting attention due to the provision of airbags and the like.

[0003]

However, the above-mentioned conventional techniques have not been able to provide a lightweight and soft steering wheel that satisfies these requirements in all respects. That is, for example, the one using the urethane integral skin foam has a problem that the metal core and the surface soft material are separated during the grip operation. In addition, there is a problem of environmental damage due to CFC gas when urethane is foamed. In addition, there are various problems in that the molding cycle is long and the yield is poor, so that there is a problem in cost and mass productivity, and the product obtained is not sufficiently lightweight. Also, a curable adhesive is applied to the metal core, and PVC, polyurethane (P
There are some types in which a soft layer such as U) is formed, but the cleaning, the application of the adhesive, the curing and the like in the bonding work step are complicated, and there is a problem in mass productivity. In addition, there is a problem that the grip feeling is not sufficiently improved and the weight reduction is unsatisfactory.

[0004]

[Means for Solving the Problems]

[Summary of the Invention] The present inventors have conducted extensive studies in view of the above problems, and when molding a metal insert molded body in which the surface of a metal core is coated with a soft soft material, a specific soft material is used, By interposing a specific hard resin layer between the metal core and the soft material on the surface, the surface gives a soft feeling, is excellent in handle operability, and is a hard resin material without using an adhesive. Since the soft resin material and the metal core can be firmly fixed to each other, the peeling phenomenon does not occur even during the grip operation, and the weight of the metal core is improved by interposing the high strength hard resin material. The present invention has been completed based on the knowledge that the steering wheel can be reduced in weight by reducing the above. That is, the steering wheel of the present invention has a metal core having a diameter of 4 to 8 mm inserted therein, a surface layer composed of an olefin-based or styrene-based thermoplastic elastomer, and an inorganic filler mixed therein. Elastic modulus (JIS-K7203) exceeds 70,000
3 ~ 10m wall thickness adjusted to 170,000kg / cm ²
m of the propylene-based resin layer is interposed therebetween to be laminated. Moreover, another method of manufacturing a steering wheel according to the present invention is to insert a metal core having a diameter of 4 to 8 mm into a mold, and then mix an inorganic filler in the mold to obtain a modulus of elasticity (JIS -K7203)
Of the propylene-based resin adjusted to exceed 70,000 to 170,000 kg / cm ² by injection molding with a wall thickness of 3 to 10 mm and coating the metal core with a propylene-based resin layer, and then olefin-based or styrene-based resin A thermoplastic elastomer is injection-molded to coat the surface of the propylene-based resin layer with an olefin-based or styrene-based thermoplastic elastomer.

[Detailed Description of the Invention] [I] Steering Wheel (1) Constituent Materials (a) Metal Core Various metal can be cited as the metal core to be inserted into the steering wheel of the present invention. In particular, it is preferable to use steel such as carbon steel and stainless steel, and metal such as iron alloy, aluminum alloy, magnesium alloy, and brass. Such metal cores typically have a diameter of 4
It is a rod-shaped product having a diameter of -8 mm, preferably 5-7 mm, which is formed into a steering wheel shape. If the diameter is too thin, it will be difficult to withstand the strength, and if it is too thick, it will not be possible to reduce the weight and the grip feeling will be unsatisfactory. In addition,
There is no problem even if the metal core has an irregular shape.

(B) Olefin-based or styrene-based thermoplastic elastomer Further, the olefin-based or styrene-based thermoplastic elastomer (hereinafter simply referred to as "TPE") used in the steering wheel of the present invention is as follows. Can be mentioned. Olefin-based TPE Olefin-based TPE includes olefin-based resins such as polypropylene and polyethylene and ethylene / propylene-based rubber (EPR), ethylene / butene-based rubber (EBR)
It is a blend with olefinic rubbers such as, for example, "Thermoran" manufactured by Mitsubishi Petrochemical Co., Ltd., "Milastomer" manufactured by Mitsui Petrochemical Co., Ltd., and "Sumitomo T" manufactured by Sumitomo Chemical Co., Ltd.
"PE", "Santoplain" manufactured by Nippon Monsanto Co., Ltd., and the like. Styrene-based TPE As a styrene-based TPE, styrene / butadiene block copolymer, styrene / isoprene block copolymer or hydrogenated derivatives thereof (styrene / ethylene / butylene / styrene copolymer, styrene / ethylene / propylene / styrene copolymer) are used as compounding ingredients. Elastomers including, specifically, "Lavalon" manufactured by Mitsubishi Petrochemical Co., Ltd., "Sumitomo TPE-S manufactured by Sumitomo Chemical Co., Ltd."
B ”,“ Elastomer AR ”manufactured by Aron Chemical Co., Ltd.,“ Tuftec ”manufactured by Asahi Kasei Kogyo KK, and the like. As such a TPE, the above TPE can be used as it is, or a foamed product of the TPE can be used. From the viewpoint of moldability and feel, JIS-K6301 is used.
The hardness of A is preferably 10 to 80, particularly preferably 20 to 60. Further, various additional compounding components may be compounded as long as they exhibit such physical properties.

(C) Propylene-based resin The propylene-based resin material used as an intermediate layer between the metal core and the olefin-based or styrene-based TPE layer in the steering wheel of the present invention includes a propylene homopolymer or propylene as a main component. To a propylene-based resin consisting of a random or block copolymer with
An inorganic filler such as glass fiber, carbon fiber, potassium titanate fiber, metal whiskers, talc, or mica is blended to give an elastic modulus of 70,000 according to JIS-K7203.
The one adjusted to exceed 170,000 kg / cm ² is used. At this time, engineering plastics such as polyphenylene ether resin, polyamide resin, saturated polyester resin, polycarbonate resin, and polyphenylene sulfide resin are added to the propylene-based resin as an auxiliary component, preferably in an amount of 5 to 50% by weight, so that the elastic modulus is increased. It is also possible to keep it at a high level. If the elastic modulus of the propylene resin is 70,000 kg / cm ² or less, the reinforcing effect of the metal parts is small, and the weight reduction of the steering wheel is not significantly shown. Also, the elastic modulus is 170,
If it is attempted to obtain more than 000 kg / cm ^2, the mixing ratio of the inorganic filler becomes too large, so that not only the adhesiveness with the olefin-based or styrene-based thermoplastic elastomer becomes poor, but also the moldability becomes problematic. Become.

(D) Optional constituent materials In addition to the essential constituent materials of (a) to (c) above, as an optional constituent material, for the purpose of improving designability, grip feeling and operability, It is preferable to use the following coating layer forming material and leather layer forming material. Coating Layer Forming Material Examples of the material used for forming the coating layer include a primer and a paint. Specific examples of the primer include "Primac 1100" manufactured by NOF Corporation, "MEX-5440" manufactured by Sakai Chemical Co., Ltd., and the like. Specific examples of the paint include "Suncoat Grace V" manufactured by Nagashima Paint Co., Ltd., "MEX-6047" manufactured by Sakai Chemical Co., Ltd., and the like. Leather layer forming material As the leather used for forming the leather layer, natural or artificial leather can be used, and the thickness is 1 mm.
Specific examples include front and rear cowhide (steer, cow, kip, calf, etc.), natural leather such as sheep leather, synthetic leather such as vinyl chloride resin synthetic leather, and synthetic leather such as polyurethane synthetic leather.

(2) Structure (a) Indispensable constituent layers The steering wheel of the present invention basically comprises
It is composed of the essential constituent material of (c), but is optionally coated or coated with the optional constituent material of (d) above. That is, the steering wheel 1 of the present invention
The overall structure is as shown in FIG. 1, but the internal structure is such that, as shown in FIG. 2, the metal core 2 processed to have a diameter of 4 to 8 mm is inserted inside and the outside is formed. A propylene-based resin layer (hard layer) 3 coated with an inorganic filler having a wall thickness of 3 to 10 mm, preferably 4 to 8 mm, which is coated by injection molding, is formed, and the outside of the propylene resin layer is injection-molded. Olefin-based or styrene-based thermoplastic elastomer layer (soft layer) 4 having a wall thickness of 3 to 10 mm, preferably 4 to 8 mm
Are formed. If the thickness of the propylene-based resin layer (hard layer) is less than the above numerical value, the reinforcing effect of the inserted metal core becomes small and the moldability becomes difficult. If the propylene-based resin layer (hard layer) exceeds the above numerical value, the olefin-based or styrene-based thermoplastic elastomer layer cannot have a sufficient thickness and it is difficult to obtain a good grip feeling. Further, an olefin-based or styrene-based thermoplastic elastomer layer (soft layer)
If the wall thickness is less than the above value, a soft feeling cannot be imparted, and the grip feeling is not good. If the thickness is too thick, the operability will be poor.

(B) Arbitrary constituent layers On the surface of the steering wheel 1 having such a structure,
If necessary, as shown in FIG. 2, a coating layer 5 composed of a primer layer and / or a coating film, or a leather coating layer 6 having a wall thickness of about 1 mm can be formed. A coating layer 5 comprising such a primer layer and / or a coating film, or
By forming the leather coating layer 6 having a wall thickness of about 1 mm, it is possible to further improve the design, grip feeling and operability.

[II] Manufacture of Steering Wheel (1) Manufacturing Process The steering wheel of the present invention can be manufactured by various methods. Among them, the manufacturing process is performed by the following first step and second step. Preferably. (a) First step A metal core having a diameter of 4 to 8 mm to be inserted is fixed in a mold, and a propylene resin containing the inorganic filler is injection-molded to obtain a propylene resin layer (hard layer). Has a wall thickness of 3 to 10 mm, preferably 4 to 8 m
The surface of the metal core is coated so that the thickness becomes m. (b) Second step Next, the molded body obtained in the first step is transferred into another mold and fixed, and the olefin-based or styrene-based thermoplastic elastomer is injection-molded again, thereby The thickness of the olefin or styrene thermoplastic elastomer layer (soft layer) is generally 3 to 10 mm, preferably 4 to 8 m.
It is coated so that it becomes m.

(2) Manufacturing Conditions As an injection molding machine used in the injection molding in the first step and the second step, there can be mentioned a generally used in-line screw type machine. Typical injection molding conditions are as shown in Table 1 below.

Table 1 First step Second step Molding temperature: 190 to 250 ° C. 180 to 250 ° C. Injection pressure: 500 to 1000 kg / cm ² 500 to 1000 kg / cm ² Mold temperature: 20 to 50 ° C. 20 to 50 ° C. Cooling time: 10 to 40 sec 10 to 70 sec The injection molding In the above, by foaming the TPE layer, it is an effective means because it is possible to obtain a molded article having a softer touch feeling. The foaming may be carried out by a conventional method using a physical foaming agent or a chemical foaming agent so that the volume becomes about 1.2 to 2 times.

(3) Coating step / leather coating step The surface of the molded body obtained in the first step and the second step is
Further, it is preferable to form a coating layer and / or a leather coating layer. Painting process In the painting here, the paint is generally applied after the primer treatment. As the primer and the paint, those mentioned above can be mentioned. Although various coating methods can be adopted for the coating, it is usually preferable to apply by spraying. Leather coating step Generally, a leather coating layer is formed by coating a part or the whole of the molded body with a leather to which an adhesive or a pressure sensitive adhesive is applied, as shown in FIG. It is finished by sewing and forming the sewn portion 7. In some cases, the sewing process may be omitted and the coating may be performed only by adhesion with an adhesive.

[0015]

EXAMPLES In order to further describe the steering wheel and the manufacturing method thereof according to the present invention, examples and comparative examples will be specifically described below. The raw materials used in the examples were as shown below. The quality of the obtained steering wheel was evaluated according to the method described below. (1) Raw materials (a) Metal core As a metal core for steering wheel, diameter 6mm
^φ carbon steel for automobiles (STKM) JIS-G3445 was used.

(B) Propylene resin P-1 "Mitsubishi Polypro" MA3 (MFR 11g /
10 minutes, density 0.90 g / cm ³ , flexural modulus (JIS-
K7203) 12,500 kg / cm ² ) was mixed with 40% by weight of glass fiber (diameter 10 μm, length 3 mm) and 10% by weight of maleic anhydride-modified polypropylene and kneaded at a temperature of 230 ° C. in a granulator. Composite material (MFR5
g / 10 minutes, density 1.21 g / cm ³ , flexural modulus (J
IS-K7203) 80,000 kg / cm < ² >). P-2 Mitsubishi Yuka Co., Ltd. "Mitsubishi Polypro" BC3B, (MFR9g
/ 10 min, density 0.90 g / cm ³ ), poly (2,6-dimethyl-1,4-phenylene ether manufactured by Nippon Polyether Co., Ltd. (intrinsic viscosity measured in chloroform at 30 ° C. is 0.3 dl / 25% by weight of glass) and 40% by weight of glass fiber (diameter 10 μm, length 3 mm) and kneaded in a granulator at a temperature of 250 ° C. (M
FR 6 g / 10 minutes, density 1.30 g / cm ³ , flexural modulus (JIS-K7203) 110,000 kg / c
m ² ). P-3 "Mitsubishi PolyPro" MA3 manufactured by Mitsubishi Petrochemical Co., Ltd. was mixed with 25% by weight of glass fiber (diameter 10 μm, length 3 mm) and 5% by weight of maleic anhydride-modified polypropylene, and the temperature was 230 ° C. in a granulator. Composite material kneaded with (MFR 5g / 1
0 minutes, density 1.09 g / cm ³ , flexural modulus (JIS-
K7203) 40,000 kg / cm ² ). P-4 "Mitsubishi Polypro" MA3 manufactured by Mitsubishi Petrochemical Co., Ltd. was blended with 32% by weight of polyamide "MC112L" manufactured by Kanebo and 60% by weight of glass fiber (diameter 10 μm, length 3 mm) and granulated with a granulator 250. Composites kneaded at a temperature of ℃ (density 1.
65 g / cm ³ ), flexural modulus (JIS-K7203) 1
75,000 kg / cm ² )

(C) Olefin-based or styrene-based thermoplastic elastomer TPS-1 Lavalon "T-331C (density 0.9 g / cm ³ , JI
S-A hardness 28) TPS-2 "Lavalon" MJ-4300C (density of 0.
9 g / cm ³ , JIS-A hardness 45) TPO-1 Mitsubishi Yuka Co., Ltd. "Thermo run" 3551 (density 0.9 g /
cm ³ , JIS-A hardness 55)

(2) Quality evaluation grip slip test Using a measuring device as shown in FIG. 3, the shaded portions 1a, 1b, 1c of the steering wheel 1 shown in FIG.
A pressing tool as shown in FIGS. 5 (a) and 5 (b) was used to clamp from all sides, and the load was applied at a speed of 5 to 10 seconds / 90 degrees, and a torque of 35 kg was applied. After that, when the torque was removed, the grip returned to its original state was rated as good, and the one that did not return to its original state was rated as x. Gripping sensation test When the obtained molded product was lightly gripped, a product that easily fits in the hand and had appropriate elasticity was judged to be good. 86 panelists (46 men, 40 women, age 19-)
52 years old) monitor test. Only when 80% or more of the people satisfied the steering wheel performance of the present invention was evaluated as ◯. On the other hand, when less than 80% of people were judged to be good, it was rated as x. Steering wheel operability test When the steering wheel was gripped and rotated in the actual steering wheel operation, a person who felt that there was an appropriate repulsive force without bottoming out and a firm feeling was judged to be good. In a monitor test with the same personnel configuration as the grip feeling test, 80% or more of the people judged that the steering wheel performance of the present invention was satisfied only when judged to be good. On the other hand, 80 people are judged to be good.
When it was less than%, it was rated as x. Parallel Bending Strength As shown in FIG. 7, a load of 100 kg was applied to the steering wheel, and what was deformed by 20 mm or more from the original state was regarded as having insufficient strength and marked as x. In addition, those having a degree of deformation of less than 20 mm from the original state were evaluated as good and evaluated as good.

Example 1 First step A metal core having an outer diameter of 6 ^mmφ (having a shape shown in FIG. 1) was mounted in a mold having an inner diameter of a cavity of 16 ^mmφ , and an inorganic filler was added to the metal core. The hard propylene resin (P-1) was coated with an injection molding machine so that the thickness was 5 mm. The injection molding conditions at this time are as follows: molding temperature 220
° C., injection pressure 700 kg / cm ^2, mold temperature 30 ° C., was carried out in the cooling time 30 sec. The second step the obtained molded body cavity inner diameter mounted in a mold of 30 mm ^phi, styrenic TPE in the molded body (TPS-Vicenzo
It was coated with an injection molding machine so that the wall thickness of 2) was 7 mm. The injection molding conditions at this time were: molding temperature 220 ° C., injection pressure 650 kg / cm ³ , mold temperature 30 ° C., cooling time 6
It was performed in 0 seconds. Leather coating step The obtained molded body was sewn into a shape as shown in FIG. 6 using natural leather of cowhide having an average thickness of 1 mm. Evaluation Regarding the product performance of the steering wheel thus obtained, the performance was evaluated by the four items of grip slip test, feel test, operability, and parallel bending strength, and the results are shown in Table 2.

Example 2 First Step A metal core having an outer diameter of 6 mm ^φ (having a shape shown in FIG. 1) was mounted in a mold having an inner diameter of a cavity of 16 mm ^φ , and the same injection molding as in Example 1 was performed. This metal core was coated with a hard propylene resin (P-2) containing an inorganic filler under the conditions. Second step The obtained molded body is mounted in a mold having a cavity inner diameter of 30 ^mmφ , and an injection molding machine (same as in Example 1) is used so that the thickness of styrene-based TPE (TPS-2) is 10 mm. Injection molding conditions). Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The quality of the obtained steering wheel was evaluated, and the results are shown in Table 2.

Example 3 First Step Using a metal core having an outer diameter of 6 ^mmφ (having a shape shown in FIG. 1), the cavity was mounted in a mold having an inner diameter of 20 ^mmφ , and the metal core having the outer diameter of 6 ^mmφ was used. Hard propylene resin (P-
1) was coated. The second step the obtained molded body cavity inner diameter mounted in a mold of 30 mm ^phi, similarly to styrene TPE (TPS-2) injection molding machine so the thickness is 5mm and (EXAMPLE 1 This Injection molding conditions). Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

Example 4 First Step In the same manner as in Example 1, a metal core was coated with a hard propylene resin (P-1) containing an inorganic filler. Second step The obtained molded body was mounted in a mold having a cavity inner diameter of 30 ^mmφ , and styrene-based TPE (TPS-2) 95
"Fine blow" manufactured by Mitsubishi Yuka Co., Ltd. as a weight part and a foaming agent
Using a material obtained by blending 5 parts by weight of S20N, styrene-based TPS-2 was coated while being foamed 1.3 times by an injection molding machine. The injection molding conditions at this time are as follows: molding temperature 220
℃, injection pressure primary 20kg / cm ² , secondary 15kg / cm
^The pressure was set to ² and the mold pressure was 30 ° C., and the cooling time was 80 sec. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

Example 5 The first step and the second step were carried out in the same manner as in Example 1 to obtain a molded body. The obtained molded body was painted and finished under the following coating conditions. Pretreatment: Wiping with isopropyl alcohol Primer: Sakai Chemical Co., Ltd. MEX-5440: Thinner MEK: Primer wall thickness 7 μm Drying: Temperature Normal temperature: Time 30 minutes Coating material: Main agent Sakai Chemical Co., Ltd. “MEX-604”
7 ”: Hardener“ F-3 ”manufactured by Sakai Chemical Co., Ltd .: Solvent thinner: Coating thickness 20 μm Baking: Temperature 80 ° C .: Time 30 min Evaluation of the obtained steering wheel performance, and the results are shown in Table 2. Show.

Example 6 The procedure of Example 1 was repeated except that the material of TPO-1 was used in the second step. The results are shown in Table 2.

[0025] The metal core of the Comparative Example 1 The first step outer diameter 6 mm ^phi, an inner diameter of the cavity is 30mm
^It is installed in a ^φ mold and a hard propylene resin (P
-3) was coated with an injection molding machine to a thickness of 7 mm. Second step In the same manner as in Example 1, a styrene-based thermoplastic elastomer (TPS-2) was coated with an injection molding machine to a thickness of 7 mm. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

[0026] The metal core of the Comparative Example 2 The first step outer diameter 6 mm ^phi, an inner diameter of the cavity is 10mm
^It was mounted in a ^φ mold and was coated with an injection molding machine so that the hard propylene resin (P-1) containing an inorganic filler mixed therein had a thickness of 2 mm. Second step In the same manner as in Example 1, the styrene-based thermoplastic elastomer (TPS-2) was coated with an injection molding machine so that the thickness was 10 mm. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

[0027] Comparative Example 3 The metal core of the first step outer diameter 6 mm ^phi, the inner diameter of the cavity 30mm
^It was mounted in a ^φ mold, and was coated with an injection molding machine so that the hard propylene resin (P-1) containing an inorganic filler mixed therein had a thickness of 12 mm. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

[0028] Comparative Example 4 metal core of the first step outer diameter 6 mm ^phi, the inner diameter of the cavity 30mm
^It was mounted in a ^φ mold, and this was coated with a styrene-based thermoplastic elastomer (TPS-2) with a wall thickness of 12 mm by an injection molding machine. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

[0029] Comparative Example 5 The metal core of the first step outer diameter 6 mm ^phi, the inner diameter of the cavity 26mm
^It was mounted in a ^φ mold and was coated with an injection molding machine so that the hard propylene resin (P-1) containing an inorganic filler mixed therein had a thickness of 10 mm. Second step The obtained molded body is mounted in a mold having a cavity with an inner diameter of 30 ^mmφ , and the styrene thermoplastic elastomer (TPS-2) is coated with an injection molding machine so that the thickness is 2 mm. did. Leather Covering Step Next, natural leather was sewn in the same manner as in Example 1. Evaluation The performance of the obtained steering wheel was evaluated, and the results are shown in Table 2.

Comparative Example 6 The procedure of Example 1 was repeated, except that the hard propylene resin (P-1) was used instead of the hard propylene resin (P-1) in the first step. The results are shown in Table 2.
Shown in.

[0031]

[Table 1]

[0032]

The steering wheel of the present invention as described above has a metal core arranged in the center thereof and is formed to be gradually softer toward the outside, and is made of a soft olefinic or styrene thermoplastic elastomer on the outside. Since the surface layer is formed, it gives a soft feel when gripped, improves handle operability, and the force applied to the grip during grip operation is not directly transmitted to the metal core, The problem of separation from the soft surface material does not occur. Moreover, unlike the case of urethane foam, there is no problem of environmental damage due to CFC gas, and since the molding cycle is short and the yield is good, it is excellent in cost and mass productivity, and part of the metal core is mixed with an inorganic filler. Since the hard propylene resin layer is substituted, the steering wheel can be made lighter.

[Brief description of drawings]

FIG. 1 is a perspective view of a steering wheel according to an embodiment of the present invention.

FIG. 2 is an A- of the steering wheel shown in FIG.
It is a notch perspective view by cutting A line part.

FIG. 3 is a plan view of an apparatus for measuring a steering wheel grip slip test.

FIG. 4 is a plan view showing a measurement portion of a steering wheel for measuring a grip slip test.

5A and 5B are a front view and a partial side view of a push tool for clamping the steering wheel of FIG.

FIG. 6 is a partial plan view showing a sewn portion in a leather winding work test.

FIG. 7 is a side view of the steering wheel showing a direction in which a load is applied when the parallel bending strength of the steering wheel is measured.

[Explanation of symbols]

1 Steering Wheel 2 Metal Core 3 Propylene Resin Layer (Hard Layer) 4 Olefinic or Styrene Thermoplastic Elastomer Layer (Soft Layer) 5 Coating Layer 6 Leather Covering Layer 7 Stamping Tool 8 Sewing Part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B29L 31:30 4F

Claims (6)

[Claims] 1. A metal core having a diameter of 4 to 8 mm inserted therein, a surface layer composed of an olefin-based or styrene-based thermoplastic elastomer, and an inorganic filler incorporated between them to obtain a modulus of elasticity (JIS. -K7203) to 7
A steering wheel characterized in that a propylene resin layer having a thickness of 3 to 10 mm adjusted to over 10,000 to 170,000 kg / cm ² is laminated. 2. The steering wheel according to claim 1, wherein the surface is painted. 3. The steering wheel according to claim 1, wherein the surface is coated with natural or artificial leather. 4. A metal core having a diameter of 4 to 8 mm is inserted into a mold, and then an inorganic filler is blended into the mold so that the elastic modulus (JIS-K7203) exceeds 70,000 to 17
A propylene-based resin adjusted to 10,000 kg / cm ² is injection-molded with a wall thickness of 3 to 10 mm, the metal core is coated with a propylene-based resin layer, and then an olefin-based or styrene-based thermoplastic elastomer is injection-molded. Then, the surface of the propylene resin layer is coated with an olefin-based or styrene-based thermoplastic elastomer. 5. The method for producing a steering wheel according to claim 4, wherein the surface of the coating obtained by injection molding an olefin-based or styrene-based thermoplastic elastomer is further coated. 6. The method for producing a steering wheel according to claim 4, wherein the surface of the coating obtained by injection molding an olefin-based or styrene-based thermoplastic elastomer is further coated with a natural or artificial leather.