KR101734700B1

KR101734700B1 - Poly-amide resin compostion for arm of door checker device

Info

Publication number: KR101734700B1
Application number: KR1020150151777A
Authority: KR
Inventors: 황덕형; 김석환; 이은주; 박봉주
Original assignee: 현대자동차주식회사; 한국엔지니어링플라스틱 주식회사
Priority date: 2015-10-30
Filing date: 2015-10-30
Publication date: 2017-05-11

Abstract

The present invention relates to a polyamide resin composition for door checker arms. By mixing a specific amount of carbon nanotube (CNT) and a carbon fiber along with a polyamide 66 resin (PA66) which is multipurpose engineering plastic, it is possible to remarkably reduce abrasion of checkers due to dust as well as abrasion of sliders which are reciprocal perturbation components, thereby increasing overall durability and quality of door checker modules.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyamide resin composition for a door checker arm,

The present invention relates to a polyamide resin composition for a door checker arm, and more particularly to a polyamide resin composition for a door checker arm, which comprises mixing a predetermined amount of a carbon fiber, a carbon nanotube and a lubricant in a polyamide 6,6 resin to homogeneously increase hardness on the surface of the molded article, And a polyamide resin composition excellent in hardness and abrasion resistance, which improves noise during slidings.

Generally, the vehicle door is provided with a checker device for controlling the opening angle of the door and fixing the maximum opening amount. The door provided on the vehicle is pivotally mounted on a side portion of the vehicle so as to be openable and closable by a door hinge so as to be opened and closed by a user. When the door is rotated with the door hinge, the door is limited to a certain range A door checker is provided.

Therefore, Door Checker is a part that acts as a hinge of an automobile door. It is a part that prevents the door from opening suddenly or unintentionally due to the door's own load when the door is opened and closed. The door checker has a structure in which the plastic is over-molded in a shape having a concavo-convex shape in order to give a check function to a steel part connecting the door and the body. 1 is a perspective view showing a general door checker.

However, such door checkers are exposed to various dusts during use, and these dusts cause wear on the irregularities of the checkers. Since the door checker plastic is over-molded in steel, the door checker plastic has sufficient toughness so as not to cause cracks at low temperature due to the difference in thermal expansion coefficient with steel in addition to abrasion Elongation). PA46 resin, which is a super engineering plastic, is currently used as a door checker material in order to satisfy these incompatibilities, toughness and hardness (dust abrasion). However, PA46 has a high defect rate during molding due to high moisture absorption characteristics, May cause problems such as generation of noise during driving due to deterioration of physical properties.

Therefore, various attempts have been made to add various kinds of wear-resistant agents and reinforcing agents to PA66, which is relatively less sensitive to moisture absorption and has good rigidity. However, there have been limitations in obtaining results satisfying both of the opposite physical properties.

In particular, when an elastomer or an organic wear-inhibiting agent is added, the toughness problem is solved, but the hardness is lowered and the disadvantage that the abrasion due to the dust occurs rapidly is confirmed, and when the inorganic wear-resistant agent is added, a crack is generated due to the lack of toughness . In addition, when a reinforcing agent is added to a fibrous reinforcing agent to reduce the shrinkage and thermal expansion coefficient itself to prevent cracking, a relatively large filler shape compared to dust causes abrasion on the surface layer containing only PA66 resin, There is a problem that the protruded filler while being exposed to the surface accelerates the wear of the slider as a perturbing part.

Korean Patent Laid-Open Publication No. 2006-0031395 discloses that 0.005 to 2 parts by weight of an amine-substituted triazine compound (B) per 100 parts by weight of a polyoxymethylene polymer (A), an anhydride 0.01 to 5 parts by weight of a compound (C) in which 0.05 to 5% by weight of maleic acid is grafted, and 0.001 to 2 parts by weight of 1,12-dodecanedicarboxylic acid dihydrazide (D) A resin composition has been disclosed, but there is still a problem that hardness can not be improved for use as a composition for a door checker arm.

As a material that can be used in the door checker, various mechanical properties such as heat resistance, lubrication characteristics, hardness, abrasion resistance, and moldability are required to be improved.

1: Korean Patent Publication No. 2006-0031395

Accordingly, the present inventors have found that by mixing a predetermined amount of a carbon fiber (carbon fiber) and a carbon nanotube (Caborn Nano Tube) in a polyamide 66 resin (PA66) as a general engineering plastic, the wear of the checker due to dust is significantly reduced In addition, it has been found that the overall quality and durability of the door checker module can be improved by reducing the wear of the slider, which is a relatively perturbing part, and thus the present invention has been accomplished.

Accordingly, an object of the present invention is to provide a polyamide resin composition for a door checker arm excellent in hardness and abrasion resistance.

Another object of the present invention is to provide a checker arm of a door checker manufactured from the polyamide resin composition.

In order to solve the above problems, the present invention provides a polyamide resin composition comprising (A) 90 to 97% by weight of a polyamide 66 resin (PA66); (B) 2 to 7% by weight of carbon fiber; (C) 0.2 to 2% by weight of carbon nanotubes (CNT); And (D) 0.2 to 1% by weight of a lubricant. The polyamide resin composition for a door checker arm according to claim 1,

The present invention also provides a checker arm of a door checker device which is made of the polyamide resin composition and is excellent in hardness and abrasion resistance.

The polyamide resin composition according to the present invention is excellent in hardness and abrasion resistance, and the door checker arm manufactured using the same has excellent hardness, minimizes wear and noise caused by dust during driving, - Reduce the rate of export of over-molding plastics and reduce cracking.

In addition, since the present invention has injection workability equivalent to that of conventional general polyamide 6,6 resin, it is easy to manufacture molded articles such as door checker arms.

1 is a perspective view showing a general door checker device.

Hereinafter, the present invention will be described in more detail as an embodiment.

In the present invention, a predetermined amount of a carbon fiber and a carbon nanotube are mixed with a conventional general polyamide 6,6 resin having a significantly lower hardness and abrasion resistance than currently used polyamide 4,6 resin, By increasing the hardness uniformly, wear by dust and noise during operation are improved. In addition, it is possible to homogenize the hardness deviations of the localized portions caused by the application of the carbon fiber alone by mixing with the carbon nanotubes, thereby minimizing the variation of abrasion and minimizing the content of the carbon fibers, and the door checker slider ) The effect of minimizing the wear of the material was obtained. Furthermore, the problem of crack generation due to a decrease in elongation, which is a disadvantage of conventional inorganic wear-resistant materials, is solved by reducing the shrinkage ratio due to mixing of carbon fibers.

Accordingly, in order to reduce the shrinkage ratio of the polyamide 6,6 resin and improve the wear resistance of the polyamide 6,6 resin, the carbon nanotube and the carbon fiber are mixedly applied (hardness improvement improves the frictional wear resistance) A polyamide resin composition for a door checker arm which is excellent in injection moldability by injecting an EBS-based lubricant to facilitate its use.

Specifically, the present invention relates to a resin composition comprising (A) 90 to 97% by weight of a polyamide 66 resin (PA66); (B) 2 to 7% by weight of carbon fibers; (C) 0.2 to 2% by weight of carbon nanotubes (Caborn Nano Tube); And (D) 0.2 to 1% by weight of a lubricant. The polyamide resin composition for a door checker arm according to claim 1,

The polyamide 66 resin (PA66) is excellent in mechanical rigidity, heat resistance and injection workability. In the present invention, the relative viscosity is 2.0 to 3.5, and more preferably 2.1 to 3.1 Is preferably used. The relative viscosity is based on a value measured with a solution of 1 g of a resin in 100 ml of 96% sulfuric acid at 20 ° C. If the relative viscosity is less than 2.1, there may be a lack of elongation due to a low point, There is a problem that carbon nanotubes are difficult to be dispersed, and there is a problem that the resin is decomposed due to generation of high shear heat during the extrusion process.

It is preferable that the polyamide 66 resin is used in an amount of 90 to 97% by weight based on the total weight of the polyamide resin composition, but it may be adjusted according to the contents of (B) to (D).

Next, the (B) carbon fiber not only increases the strength and hardness of the polyamide resin but also reduces the shrinkage rate, minimizes the stress generated upon injection of the steel insert, thereby lowering the possibility of cracking. It is preferable to use a material having an average diameter of 5 to 10 mu m and an average length of 4 to 8 mm.

When the average diameter of the carbon fibers is less than 5 탆, the carbon fibers tend to be broken in the extrusion process. When the average diameter exceeds 10 탆, there is a limit to the strength improvement. When the average length is less than 4 mm, In case of exceeding 8 mm, there is a limit in workability in the extrusion process, so it is used within the above range.

The carbon fiber is preferably used in an amount of 2 to 7% by weight based on the total weight of the polyamide resin composition. When the carbon fiber is less than 2% by weight, the effect of improving the hardness and abrasion resistance is insignificant. Since there is a problem of promoting wear of the slider, it is used within the above range.

In addition, the carbon nanotubes (C) increase the Shore hardness and preferably have an average length of 10 to 50 μm. When the average length is less than 10 탆, there is a difficult limit in the extrusion process, and when the average length is more than 50 탆, dispersion is difficult.

The carbon nanotubes are preferably used in an amount of 0.2 to 2% by weight based on the total weight of the polyamide resin composition. When the amount is less than 0.2% by weight, the effect of improving the hardness is insignificant. When the amount is more than 2% by weight, Use within the above range.

Finally, the lubricant (D) improves the dispersibility and releasability of carbon nanotubes, and ethylene bis stearamide (EBS) is preferably used.

If the amount of the lubricant is less than 0.2% by weight, the effect of improving the dispersibility and releasability is insignificant. When the amount of the lubricant is more than 1.0% by weight, So that it is used within the above-mentioned range.

The polyamide resin composition according to the present invention composed of the above-mentioned components is excellent in hardness and abrasion resistance, so that when the door checker arm is manufactured as a molded product, the hardness of the door checker arm is increased, Can be widely used as a door checker arm material by minimizing occurrence and reducing the rate of export of plastic over-molding to steel, thereby reducing the occurrence of cracks.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1-3

Using the compositions and contents shown in the following Table 1, a polyamide resin composition was prepared and injection molded at an cylinder temperature of 270 캜 and a mold temperature of 80 캜 using an injection molding machine to obtain test pieces of Examples 1 to 3 .

Comparative Example 1 to 7

Test pieces for measuring properties of Comparative Examples 1 to 7 were injected in the same manner as in Examples 1 to 3 according to the composition ratios shown in Table 1 below.

Polyamide resin composition (unit:% by weight) division
(Unit: wt%) Example Comparative Example One 2 3 One 2 3 4 5 6 7 Polyamide 4,6 ¹⁾ - - - 100 - - - - - - Polyamide 6,6 ²⁾ 94 93 96 - 94.5 94.5 94.5 92 91.5 98 Carbon fiber ³ ⁾ 5 5 3 - - - 5 5 7.5 One Carbon nanotubes ⁴ ⁾ 0.5 1.5 0.5 - - - 0.1 2.5 0.5 0.5 Lubricant ⁵ ⁾ 0.5 0.5 0.5 - 0.5 0.5 0.5 0.5 0.5 0.5 Wollastonite ⁵ ⁾ - - - - - 5 - - - - Modified Polyethylene ⁷ ⁾ - - - - 5 - - - - - Sum 100 100 100 100 100 100 100 100 100 100 1) Polyamide 4,6: DSM Stanyl TW341 (Viscosity number 185 cm3 / g)
2) Polyamide 6,6: Relative Viscosity 2.7, molecular weight 16,000 g / mol
3) Carbon fiber: 7 탆 diameter, Chopped Length 6 mm
4) Carbon nanotube: MWCNT, bore diameter 7 ~ 10nm, outer diameter 12 ~ 17nm, Bundle Length Max. 20 탆
5) Lubricant: Ethylene bis stearamide (EBS)
6) Wollastonite: average size 7 μm, specific gravity 2.9, MOHS hardness 4.5, Surface Area 2.9 m2 / g
7) Modified PE: Partially Polarized Polyethylene. MODIC-AP L503 (Mitsubishi Chemical), mp 126 ° C, specific gravity 0.93

The physical properties of the test specimens prepared according to Examples 1 to 3 and Comparative Examples 1 to 7 were measured in the following manner and the physical properties thereof are shown in Tables 4 to 6 below.

Experimental Example : Measurement of physical properties

The results of physical properties shown in Tables 4 to 6 below show average values of the physical properties of five test specimens excluding the upper limit and lower limit, and the test method is as follows.

(1) Measurement of tensile strength: Measured according to ISO 527 method. The measurement unit was set to MPa.

(2) Measurement of elongation at break: Measured according to ISO 527 method. The unit of measurement was%.

(3) Measurement of Shrinkage: Measured according to ISO 294 method. The unit of measurement was%.

(4) Measurement of shore hardness: Measured according to ISO 868 method. The measurement was made by D Type.

(5) Tribological Abrasion Test 1 Measurement (Pin on Plate Abrasion Test): The surface of a test piece prepared using the friction measuring instrument shown in Table 2 was scratched under the conditions shown in Table 2, and the test piece (Mm) of the abrasive face of the abrasive material (hereinafter referred to as " material ") and the length (mm) of the abrasive face and the minor axis of the pin (Pin) Tribological Abrasion Test 1 The measurement is measured to determine the degree of wear of the door checker arm and slider material in actual molded parts.

Measurement conditions of Pin on Plate wear test division Condition Speed 50 mm / s Load 100 N Test time 30 min Dust Chart Quantity 0.3 g Pin KEPITA Ts-25A (POM) How to measure

(6) Measurement of Ring-on-Plate Wear 2: The surface of the test piece prepared by using a friction and wear measuring instrument was scratched with the conditions shown in Table 3, and then the dynamic friction coefficient, surface roughness, and noise holding time were measured. At this time, the dynamic friction coefficient and the noise holding time were directly measured by a friction wear measuring machine, and the surface roughness was measured by a surface roughness meter. Frictional wear test 2 The measurement is measured to judge the emotional quality such as the noise generation in the actual molded product.

Measurement conditions of Ring on Plate wear test division Condition Speed 50 mm / s Load 500 N Test time 120 min Dust Chart Quantity 0.3 g Ring KEPITAL TS-25A How to measure

The evaluation of the degree of abrasion is carried out by measuring the surface roughness of the plate after the test.
* The above figure shows the friction wear test 2.

Measurement results of mechanical properties Item Test Methods unit Reference value
(Target value) Example Comparative Example One 2 3 One 2 3 4 5 6 7 The tensile strength ISO 527 MPa 120
More than 140 141 125 95 80 90 138 142 167 88 Elongation at break ISO 527 % 2.5 or more 3.5 2.5 4.2 40 20 5 3.5 0.5 1.0 6.1 Shrinkage rate horizontal Vertical % 0.5 to 1.0 0.6 / 0.7 0.6 / 0.7 0.8 / 0.9 1.4 / 1.6 0.3 / 0.5 0.4 / 0.6 0.6 / 0.8 0.5 / 0.7 0.3 / 0.4 1.0 / 1.2 Shore
Hardness ISO 868 D Type 82
More than 84 84 82 84 80 80 80 84 85 81

As shown in Table 4, the polyamide resin compositions of Examples 1 to 3 were compared with the polyamide resin composition of Comparative Example 1, which was used as a conventional door chair material, and the mechanical properties such as tensile strength, elongation at break, It can be confirmed that the resin composition according to the present invention is suitable for use as a material for a door chair. In addition, Shore hardness was not improved in Comparative Examples 2 to 4 and 7, and the standard values were not satisfied even in other properties. In addition, in Comparative Examples 5 and 6, mechanical properties such as shore hardness required for a door chair arm material were satisfied, but the results of the frictional wear test described later were unsatisfactory.

Friction and abrasion test 1 Measurement result division Plate Wear depth (㎛)
(Material to be developed) Pin Wear Surface (mm)
(Relative material) Average Depth Maximum depth Long axis shorten Example 1 0.4 4.7 2.05 1.91 Example 2 0.4 4.5 2.10 2.00 Example 3 0.4 4.8 2.03 1.88 Comparative Example 1 0.4 6.9 2.09 1.91 Comparative Example 2 0.9 12.9 1.59 1.52 Comparative Example 3 0.6 10.9 2.12 2.11 Comparative Example 4 0.9 11.2 1.88 1.83 Comparative Example 5 0.4 4.6 2.31 2.29 Comparative Example 6 0.4 4.3 2.48 2.47 Comparative Example 7 0.4 4.8 2.12 1.98

As shown in Table 5, in the case of Examples 1 to 3, as compared with Comparative Example 1 and Comparative Examples 4 to 7, even though the depth of the average wear grooves of the test pieces was 0.4 탆, Can be identified.

It can be confirmed that the carbon fiber and carbon nanotube in the resin have an influence on the hardness and the frictional wear resistance of the resin, and when the content according to the present invention is exceeded, the maximum depth value of the wear groove becomes large, It can be confirmed that the wear of the surface is excessive.

Friction and abrasion test 2 Measurement result Item Test Methods unit Example Comparative Example One 2 3 One 2 3 4 5 6 7 Coefficient of friction Abrasive wear
Test 2 - 0.22 0.21 0.21 0.22 0.24 0.24 0.19 0.20 0.21 0.18 Plate surface roughness ㎛
9.7 9.6 12.3 14.9 47.3 44.2 32.3 9.5 8.8 43.5 Noise holding time sec 7 7 10 32 36 40 18 8 7 33

As shown in Table 6, the polyamide resin compositions of Examples 1 to 3 can be confirmed that the groove depth is not deep as measured from the surface roughness of the test piece (plate) compared to Comparative Example 1 which is a conventional polyamide resin composition, The maintenance time also decreased by more than four times.

In addition, Comparative Examples 2 and 3 did not satisfy the frictional wear test even when an organic wear-resistant agent or filler was added. In the case of Comparative Examples 4 to 7, even when polyamide 6,6 resin was used, When the amount of carbon nanotubes is out of the range, it can be confirmed that the result of the friction / wear test is not satisfied.

Therefore, the present invention is based on the fact that the conventional polyamide 4,6 resin has limitations such as hardness and abrasion resistance (dust abrasion resistance) in a stiff polyamide 6,6 resin in a predetermined content of carbon fibers and carbon nanotubes , It can be confirmed that it can be provided as a polyamide resin composition having physical properties more suitable for a molded article of a door checker arm.

The present invention is not only superior in mechanical strength such as tensile strength, elongation at break, shrinkage, shore strength, etc., but also can be obtained by mixing carbon fibers and carbon nanotubes with polyamide 6,6 resin, Moldability and injection workability, and can be widely applied to products requiring abrasion resistance and high hardness. Typically, it is used as a material of a door checker arm.

Claims

(A) 90 to 97% by weight of a polyamide 66 resin (PA66) having a relative viscosity of 2.0 to 3.5;
(B) 2 to 7 wt% of carbon fibers having an average diameter of 5 to 10 mu m and an average length of 4 to 8 mm;
(C) 0.2 to 2% by weight of a carbon nanotube (Caborn Nano Tube) having an average length of 10 to 50 占 퐉; And
(D) 0.2 to 1% by weight of lubricant;
And a polyamide resin composition for a door checker arm.

delete

The polyamide resin composition for a door checker arm according to claim 1, wherein the (D) lubricant is ethylene bis stearamide (EBS).

A checker arm of a door checker device excellent in hardness and frictional wear resistance produced by the polyamide resin composition of claim 1 or 5.