Composite material, bicycle part and forming method thereof

Abstract

The invention provides a composite material which comprises the following components in parts by weight: 100 parts of aromatic polyamide; 30 to 55 parts by weight of carbon fibers; and 10 to 35 parts by weight of carbon fibers having carbon nanotubes adhered to the surface thereof. The composite material can be used for forming integrally formed bicycle parts such as connected seat cushions and seat bows.

Description

Technical Field

[0001] The present invention relates to composite materials, and more particularly to bicycle parts integrally formed of composite materials, such as a connected saddle and rail. Background Art

[0002] The saddle and rail of traditional bicycle factories are two separate parts, which include a plastic-based saddle and a metal rail. Generally, after forming a plastic-based saddle, the metal rail needs to be assembled to the plastic-based saddle, and its processing technology is complex and time-consuming. Existing carbon fiber reinforced polymer composites (CFRP) cannot be injection-molded, so it is impossible to fabricate an integrally formed saddle and rail. On the other hand, the currently injection-molded materials have insufficient flexural strength, flexural modulus, and impact resistance, and thus cannot be used to fabricate integrally formed bicycle parts such as connected saddles and rails.

[0003] In summary, there is an urgent need for new composite materials with sufficient flexural strength, flexural modulus, and impact resistance to form integrally formed bicycle parts, such as connected saddles and rails. Summary of the Invention

[0004] A composite material provided by an embodiment of the present invention includes: 100 parts by weight of aromatic polyamide; 30 to 55 parts by weight of carbon fiber; and 10 to 35 parts by weight of carbon fiber with carbon nanotubes attached to the surface.

[0005] In some embodiments, the aromatic polyamide includes , where n is the number of repetitions, and the relative viscosity of the aromatic polyamide is 2.1 to 2.4.

[0006] In some embodiments, the carbon fiber is short-cut carbon fiber with a length of 200 to 400 microns.

[0007] In some embodiments, the flexural strength of the composite material is 400 MPa to 450 MPa.

[0008] In some embodiments, the flexural modulus of the composite material is greater than 30 GPa and less than or equal to 35 GPa.

[0009] In some embodiments, the impact resistance of the composite material is 10.7 Kgf to 13.5 Kgf.

[0010] A bicycle part provided by an embodiment of the present invention includes: a saddle; and a rail connected to the saddle, wherein the saddle and the rail are integrally formed of the above composite material.

[0011] In some embodiments, the weight of the bicycle part is 120 g to 150 g.

[0012] A method for forming a bicycle part provided by an embodiment of the present invention includes integrally molding the above composite material to form a connected seat cushion and seat bow.

[0013] In some embodiments, the process of integrally molding the above composite material is injection molding. Description of the Drawings

[0014] Figure 1 It is a schematic diagram of a bicycle part in an embodiment of the present invention.

[0015] Symbol Description:

[0016] 11: Seat cushion;

[0017] 13: Seat bow;

[0018] 100: Bicycle part. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0020] The composite material provided by an embodiment of the present invention includes: 100 parts by weight of aromatic polyamide; 30 to 55 parts by weight of carbon fiber; and 10 to 35 parts by weight of carbon fiber with carbon nanotubes attached to the surface. If the amount of carbon fiber used is too low, the flexural strength, flexural modulus, and impact resistance of the composite material will be insufficient. If the amount of carbon fiber used is too high, it will appear on the surface of the product, making the product unusable. If the amount of carbon fiber with carbon nanotubes attached to the surface used is too low, the flexural strength, flexural modulus, and impact resistance of the composite material will be insufficient. If the amount of carbon fiber with carbon nanotubes attached to the surface used is too high, the cost of the composite material will be too high and it will be impractical.

[0021] In some embodiments, the aromatic polyamide includes , where n is the number of repetitions, and the relative viscosity (R.V.) of the aromatic polyamide is 2.1 to 2.4 (measurement standard: ASTM D789). The higher the relative viscosity of the aromatic polyamide, the larger the molecular weight of the aromatic polyamide, that is, the larger n. If the relative viscosity of the aromatic polyamide is too small (i.e., the molecular weight of the aromatic polyamide is too low), the strength of the material body is poor, affecting the mechanical properties of the formed composite material. If the relative viscosity of the aromatic polyamide is too large (i.e., the molecular weight of the aromatic polyamide is too high), the fluidity is poor, which is not conducive to injection molding. On the other hand, if other aromatic polyamides such as PA6I, PA6T, PA66 / 6I, PA66 / 6T, or the like are used, the flexural strength, flexural modulus, and impact resistance of the composite material may be insufficient, or it may not be conducive to forming due to the too high processing temperature.

[0022] In some embodiments, the carbon fiber is a short carbon fiber with a length of 200 to 400 micrometers. If the length of the carbon fiber is too small, the cost is relatively high and it is difficult to obtain. If the length of the carbon fiber is too large, the flexural strength, flexural modulus, and impact resistance of the composite material are insufficient.

[0023] In some embodiments, the carbon fiber with carbon nanotubes attached to its surface is Namd purchased from Nitta TM . Namd TM A technique for continuously attaching carbon nanotubes to the surface of carbon fiber has been developed from multi-layered multi-walled carbon nanotubes (MWCNT, Multi Walled Carbon Nanotubes). The diameter of the multi-layered multi-walled carbon nanotubes is 10 to 20 nanometers, and the length is several micrometers. Since the multi-layered multi-walled carbon nanotubes are attached to the surface of the carbon fiber by intermolecular forces, the properties of the multi-layered multi-walled carbon nanotubes, such as electrical conductivity and impact resistance, are not damaged. It should be noted that if the carbon fiber with carbon nanotubes attached to its surface is replaced with traditional carbon nanotubes, the flexural strength, flexural modulus, and impact resistance of the composite material will decrease.

[0024] In some embodiments, the flexural strength of the composite material is 400 MPa to 450 MPa. If the flexural strength of the composite material is too low, it cannot meet the application requirements of high strength (such as bicycle parts).

[0025] In some embodiments, the flexural modulus of the composite material is greater than 30 GPa and less than or equal to 35 GPa. If the flexural modulus of the composite material is too low, it cannot meet the application requirements of high strength, such as the high flexural resistance requirements often found in bicycle parts.

[0026] In some embodiments, the impact resistance of the composite material is 10.7 Kgf to 13.5 Kgf. If the impact resistance of the composite material is too low, it cannot meet the application requirements of high strength.

[0027] A bicycle part 100 provided in an embodiment of the present invention, such as Figure 1 shown, includes a seat cushion 11 and a seat post 13 connected to the seat cushion 11. The seat cushion 11 and the seat post 13 are made of the above composite material in an integrally formed manner. It should be understood Figure 1 The bicycle part 100 shown is only an example, and those skilled in the art can adjust the shape and position of the seat cushion 11 and the seat post 13 according to needs, as long as the seat cushion 11 and the seat post 13 are connected and have the functions of the seat cushion 11 and the seat post 13 defined in this technical field, and are not limited to Figure 1 the style shown.

[0028] In some embodiments, the weight of the bicycle part is from 120 g to 150 g. Since the seat cushion 11 and the seat bow 13 are integrally formed, their weight is much lighter than the total weight of a conventional seat cushion and a metal seat bow (for example, about 1 / 3 of the total weight of a conventional seat cushion and a metal seat bow).

[0029] A method for forming a bicycle part provided by an embodiment of the present invention includes integrally forming the above composite material to form a connected seat cushion 11 and seat bow 13.

[0030] In some embodiments, the process of integrally forming the above composite material is injection molding. Compared with the conventional method of installing a metal seat bow on the seat cushion after forming the seat cushion, the method of integrally forming the connected seat cushion 11 and seat bow 13, such as injection molding, is simpler and can effectively reduce the processing time and cost.

[0031] For example, the composite material can be heated to 230°C to 270°C in an injection cylinder, and the composite material can be injected into a mold at 120°C to 160°C under a pressure of 50 MPa to 120 MPa, and then cooled for 80 seconds to 120 seconds to obtain a product such as the bicycle part 100, such as the connected seat cushion 11 and seat bow 13. It can be understood that in addition to forming an integrally formed bicycle part 100, such as the connected seat cushion 11 and seat bow 13, the above composite material can also be used for other products and can be assembled with other components, and is not limited to integrally formed products.

[0032] To make the above content, other objects, features, and advantages of the present invention more obvious and understandable, the following specific embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows:

[0033] [Embodiment]

[0034] In the following embodiments, the chemical structure of the aromatic polyamide is , its relative viscosity (R.V.) is from 2.1 to 2.4 (the measurement standard is ASTM D789), and it is S6001-MXD6 purchased from Mitsubishi Chemical.

[0035] The chemical structure of another aromatic polyamide PA66 / 6I is , its relative viscosity (R.V.) is from 2.2 to 2.4 (the measurement standard is ASTM D789), and it is purchased from Arkema SA. The short carbon fiber is TC42 purchased from Tailang, and the carbon fiber with carbon nanotubes attached to the surface is Namd purchased from Nitta TM .

[0036] In the following embodiments, the measurement standards for the flexural strength and flexural modulus of the composite material are ASTM D790, and the measurement standard for the impact strength is ASTM D256.

[0037] Comparative Example 1

[0038] Take 100 parts by weight of aromatic polyamide S6001-MXD6, 58 parts by weight of chopped carbon fiber TC42, and 8 parts by weight of carbon fiber Namd with carbon nanotubes attached to the surface TM , and place them into a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 383 MPa, the flexural modulus is 28 GPa, and the impact strength is 10.3 Kgf. It can be seen from Comparative Example 1 that when the dosage of carbon fiber Namd with carbon nanotubes attached to the surface TM is low, the flexural strength, flexural modulus, and impact resistance of the composite material are insufficient.

[0039] Example 1

[0040] Take 100 parts by weight of aromatic polyamide S6001-MXD6, 50 parts by weight of chopped carbon fiber TC42, and 16 parts by weight of carbon fiber Namd with carbon nanotubes attached to the surface TM , and place them into a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 413 MPa, the flexural modulus is 33 GPa, and the impact resistance is 12.8 Kgf.

[0041] Inject-mold the above composite material to integrally form a bicycle part 100, which includes a connected seat cushion 11 and a seat bow 13, as Figure 1 shown. The temperature of the injection cylinder is 265 °C, the mold temperature is 150 °C, the injection pressure is 50 MPa, the injection time is 30 seconds, and the cooling time is 90 seconds. The product weight is only 146 grams (about 1 / 3 of the weight of a traditional seat cushion with a metal seat bow). The product density is 1.40 g / cm 3 .

[0042] Example 2

[0043] Take 100 parts by weight of aromatic polyamide S6001-MXD6, 42 parts by weight of chopped carbon fiber TC42, and 25 parts by weight of carbon fiber Namd with carbon nanotubes attached to the surface TM , and place them into a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 407 MPa, the flexural modulus is 31.6 GPa, and the impact strength is 12.5 Kgf.

[0044] Example 3

[0045] Take 100 parts by weight of aromatic polyamide S6001-MXD6, 33 parts by weight of chopped carbon fiber TC42, and 33 parts by weight of carbon fiber Namd with carbon nanotubes attached to the surface TM, it is placed in a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 419 MPa, the flexural modulus is 32 GPa, and the impact strength is 12.5 Kgf.

[0046] Comparative Example 2

[0047] Take 100 parts by weight of aromatic polyamide S6001-MXD6 and 67 parts by weight of chopped carbon fiber TC42 and place them in a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 391 MPa, the flexural modulus is 28 GPa, and the impact strength is 10.6 Kgf. It can be seen from Comparative Example 2 that without carbon fiber Namd with carbon nanotubes attached to the surface TM , the flexural strength, flexural modulus and impact strength of the composite material are insufficient.

[0048] Comparative Example 3

[0049] Take 100 parts by weight of aromatic polyamide PA66 / 6I and 67 parts by weight of chopped carbon fiber TC42 and place them in a twin-screw extruder for mixing and pelletizing to form a composite material. The flexural strength of this composite material is 400 MPa, the flexural modulus is 25 GPa, and the impact strength is 14.9 Kgf. It can be seen from Comparative Example 3 that without carbon fiber Namd with carbon nanotubes attached to the surface TM , the flexural strength and flexural modulus of the composite material are insufficient.

[0050] Comparative Example 4

[0051] Take the composite material NL8340 purchased from Daito Resin Chemical Co., Ltd. and measure its properties. It contains 100 parts by weight of S6001-MXD6 and 67 parts by weight of long fiber carbon fiber. The flexural strength of this composite material is 369 MPa, the flexural modulus is 27 GPa, and the impact strength is 13.9 Kgf.

[0052] Comparative Example 5

[0053] Take the composite material 6128 purchased from Akroloy and measure its properties. It contains 100 parts by weight of polyamide and 67 parts by weight of carbon fiber. The flexural strength of this composite material is 322 MPa, the flexural modulus is 27 GPa, and the impact strength is 8.9 Kgf.

[0054] Comparative Example 6

[0055] 100 parts by weight of aromatic polyamide S6001-MXD6, 50 parts by weight of chopped carbon fiber TC42, and 16 parts by weight of carbon nanotubes (MWCNT purchased from Techinstro) were placed into a twin-screw extruder for melt compounding and pelletizing to form a composite material. The flexural strength of this composite material was 402 MPa, and the flexural modulus was 30 GPa. As can be seen from Comparative Example 6, if carbon nanotubes were used to replace the carbon fiber Namd with carbon nanotubes attached to its surface TM , the flexural strength and flexural modulus of the composite material decreased (compared with Example 1).

[0056] Comparative Example 7

[0057] 100 parts by weight of aromatic polyamide MXD6 and 100 parts by weight of chopped carbon fiber TC42 were placed into a twin-screw extruder for melt compounding and pelletizing to form a composite material. The flexural strength of this composite material was 435 MPa, the flexural modulus was 30 GPa, and the impact strength was 14 Kgf. However, after this composite material was injection molded into an integrally formed seat cushion and seat bow, the carbon fiber appeared on the surface of the product and it could not be used.

[0058] Although the present invention has been disclosed above with several embodiments, it is not intended to limit the present invention. Those skilled in the art can make any changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the claims.

[0059] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only specific embodiments of the present invention and is not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A composite material, comprising: 100 parts by weight of aromatic polyamide; 30 to 55 parts by weight of carbon fiber; and 10 to 35 parts by weight of carbon fiber with carbon nanotubes attached to the surface.

2. The composite material according to claim 1, wherein The aromatic polyamide comprises: , where n is the number of repetitions, and the relative viscosity of the aromatic polyamide is 2.1 to 2.

4.

3. The composite material according to claim 1, wherein, The carbon fiber is short-cut carbon fiber with a length of 200 to 400 microns.

4. The composite material according to claim 1, wherein The flexural strength of the composite material is 400 MPa to 450 MPa.

5. The composite material according to claim 1, wherein The flexural modulus of the composite material is greater than 30 GPa and less than or equal to 35 GPa.

6. The composite material according to claim 1, wherein, The impact resistance of the composite material is 10.7 Kgf to 13.5 Kgf.

7. A bicycle part, comprising: a saddle; and a seat post, connected to the saddle; wherein the saddle and the seat post are integrally formed from the composite material according to claim 1.

8. The bicycle part according to claim 7, wherein, The weight of the bicycle part is 120 g to 150 g.

9. A method for forming a bicycle part, comprising: integrally forming the composite material according to claim 1 to form a connected saddle and a seat post.

10. The forming method of the bicycle part according to claim 9, wherein, The process of integrally forming the composite material according to claim 1 is injection molding.

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