KR101876062B1 - Polypropylene resin composition for Tail gate inner panel, and molded articles thereof - Google Patents

Abstract

The present invention relates to a polypropylene resin composition for a tailgate inner panel comprising a predetermined amount of a modified polypropylene resin, a long fiber, an scratch-resistant agent, and a flow-enhancing agent in a polypropylene resin and excellent in appearance and mechanical properties.
The tailgate inner panel made of the composition of the present invention can reduce the number of parts of the tailgate and lighten the outer panel of the car body, and can further simplify the process by reducing the number of steps for installing tailgate trim in the design line.

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition for a tailgate inner panel and a molded article thereof,

The present invention relates to a polypropylene resin composition for a tailgate inner panel having excellent appearance and scratch resistance, and a molded product thereof, comprising a predetermined amount of a modified polypropylene resin, a long fiber, an scratch resistant agent and a flow promoter.

Recently, automobiles have been taking a lot of measures to reduce the weight of automobiles to improve fuel efficiency. Plastic fenders or tailgates have been applied to the automobile industry for 30 years to reduce the weight of body panels. Currently, the company has developed and mass-produced BIW (Body In White) with carbon fiber to make a lighter body. .

Here, the tail gate is a rear panel for the RV, which is located between the side outer panel and the bumper, and is a part used as a structural component as well as an exterior component.

The main roles of these tailgates are structural stiffness, constant clearance and step difference with surrounding components, and color matching.

In addition, tailgate is equipped with external parts such as spoiler, garnish and back panel molding on steel assy panel. In the inner panel, steel reins are welded in order to attach parts related to operating tube. Lifter reinforcements, wiper motor reinforcements, and hinge reinforcements are molded to a thickness of 1.2 mm and welded to the inner panel.

Most of these external components are made of ABS resin. In the automobile industry, plastic tailgates are being mass produced by integrating external parts into the outer plate for a long time. The inner panel also has equal rigidity by removing the steel reinforcements and adding thickness and ribs to the area.

The initial tailgate used SMC (sheet molding composite) thermosetting composites for the stiffening of the shell and inner panel, but the outer panel was made into a tailgate with PC, PBT, PC and ABS.

However, at present, TPO resin is applied for more lightweight effect, and PP and LFT materials are applied to inner panel. However, PP and LFT materials for tailgate internals have similar properties to conventional LFT materials, but there are additional items that must be satisfied.

Specifically, the tailgate inner panel material plays a large role in achieving structural rigidity in the component assy, but also serves to eliminate some tailgate trim. Currently, the tailgate trim is equipped with three pieces of upper, side and lower, and the side part is implemented on the inner panel to make it possible to erase parts.

Therefore, there is a need to provide a polypropylene resin composition which is more suitable for tailgate inner panel manufacture which can simultaneously satisfy excellent external appearance and mechanical properties such as scratch resistance.

1: Korean Patent Publication No. 2015-72558

Accordingly, the present inventors have found that if a polypropylene resin contains a predetermined amount of modified polypropylene resin, long fiber, scratch agent and flow promoter under specific conditions, it is possible to manufacture a tailgate inner panel having excellent appearance and excellent scratch resistance and mechanical properties And the present invention has been completed.

Accordingly, an object of the present invention is to provide a polypropylene resin composition for a tailgate inner panel.

It is another object of the present invention to provide a tailgate inner panel made of the composition.

In order to solve the above problems, the present invention provides a polypropylene resin composition comprising (A) 10 to 86% by weight of a polypropylene resin which is a mixture of at least one selected from the group consisting of a propylene homopolymer and a propylene-ethylene copolymer; (B) 2 to 10% by weight of a modified polypropylene resin; (C) 10 to 70% by weight of long fiber; (D) from 1 to 5% by weight of scratches; And (E) 1 to 5% by weight of a flow enhancer, based on the total weight of the polypropylene resin composition.

The present invention also provides a tailgate inner panel made of the polypropylene resin composition.

The polypropylene resin composition according to the present invention realizes excellent appearance and color without appearance abnormality even without embossed embossing, and is excellent in scratch resistance and can be more suitably applied to a tailgate inner panel. Also, the tailgate inner panel thus manufactured can reduce the number of parts of the tailgate and lighten the inner panel, and further reduce the number of steps for installing the tailgate trim in the design line, thereby simplifying the process.

1 shows a view of a tailgate inner panel.

The present invention provides a polypropylene resin composition for a tailgate inner panel comprising a tailgate polypropylene resin, a modified polypropylene resin, a scratch resistant agent, and a flow enhancer. Each of the components constituting the polypropylene resin composition according to the present invention will be described in more detail as follows.

First, the polypropylene resin (A) in the present invention is a mixture of at least one selected from the group consisting of a propylene homopolymer (a1) and a propylene-ethylene copolymer (a2).

The propylene homopolymer (a1) preferably has a melt index (MeltIndex) of 230 g / 10 min to 25 g / 10 min. If the melt index is less than 10 g / 10 min, the impregnation with the long glass fiber is lowered and the rigidity can be lowered. If the melt index is more than 25 g / 10 min, the impact property is not good.

In addition, the propylene-ethylene copolymer (a2) preferably has a viscosity at 230 ° C of 100 to 2,000 g / 10 min. If the melt index is less than 100 g / 10 min, the impregnation with the long glass fiber is lowered and the appearance defects due to insufficient flowability may occur. If the melt index is more than 2000 g / 10 min, the impact property is poor.

Next, the modified polypropylene (B) serves to uniformly disperse the thermoplastic elastomer and the inorganic filler in the polypropylene resin, and the polypropylene polymer is obtained by grafting an unsaturated carboxylic acid or a derivative thereof.

Specifically, the unsaturated carboxylic acid or its derivative is characterized by being at least one member selected from the group consisting of maleic acid, acrylic acid, methacrylic acid and maleic anhydride, and it is preferable to use 0.5 to 5% by weight of the unsaturated carboxylic acid or its derivative, Is 0.7 to 1.5% by weight. This is because the dispersibility in the grafting is more excellent within the above range. Further, the weight average molecular weight of 100 to 5,000 g / mol is more useful for improving the dispersibility.

The modified polypropylene preferably comprises 2 to 10% by weight based on the total weight of the polypropylene resin composition. When the modified polypropylene is less than 2% by weight, there is a problem of deterioration of physical properties due to the impregnation deterioration and defective appearance of the injection appearance, and when it exceeds 10% by weight, the stiffness and impact strength are lowered.

Next, the long fibers (D) are used for improving mechanical properties, and it is preferable to use glass fibers having a diameter of 10 to 30 탆. When the diameter is less than 10 탆, there arises a problem that a single yarn is produced when the product is produced by extrusion, and when the diameter exceeds 30 탆, the processability and impregnability are lowered.

In addition, the long glass fiber is composed of E glass, ECR glass improved in corrosion resistance, S, S-2, R, T glass, Acid-resistant seed, CA GLASS, and the like can be used, and E-GLASS is particularly preferable from a commercial point of view.

Furthermore, the long fiber pellets impregnated in the matrix resin preferably have a chop strand of 6 to 16 mm. When the length of the pellet is less than 6 mm, the remaining fiber length is lowered and the impact resistance is lowered. When the pellet length exceeds 16 mm, the product processing and formability are lowered.

In addition, the long fibers preferably comprise 10 to 70% by weight based on the total weight of the polypropylene resin composition. When the content of the long fibers is less than 10% by weight, mechanical properties such as tensile strength, bending strength and impact strength deteriorate. When the content of the long fibers exceeds 70% by weight, there is a problem of defective appearance due to lack of fluidity. .

The scratch resistance (D) was introduced to improve the scratch resistance. The scratch resistance (D) was 13 to 15 g / 10 min (230 ° C, 10 kg) and the melting point was 92 to 95 ° C. Is an olefin-acrylate-based copolymer in the form of a pellet having an amine group (-NH2) introduced therein.

Component (D), which is an olefin-acrylate copolymer, is a specially designed functional polymer, and is known to have 18 to 24% by weight of a monomer unit containing an amine group in the olefin-acrylate copolymer.

The olefin-acrylate copolymer component is synthesized in order to induce improvement of the scratch resistance on the surface without deteriorating the thermal and physical properties in the product. It is an object of the present invention to provide an olefin- Can be expected to cause the migration of the olefin-acrylate-based copolymer component to increase the slip property of the surface through the change in the composition on the surface and increase in the content. In addition, the olefin units in the olefin-acrylate copolymer component can maintain compatibility with the polypropylene composite resin, thereby minimizing changes in physical properties.

Thus, in the present invention, the optimum conditions were found through the change of the amine group content in the olefin-acrylate copolymer and the content of the olefin-acrylate copolymer component in the composite resin, and then the molded article was injected. The olefin- The content of the copolymer chain is preferably 1 to 5 wt%, more preferably 2 to 4 wt%, based on the total weight of the polypropylene resin composition. When the scratch resistance exceeds 5% by weight, the rigidity and elongation tend to decrease. When the scratch resistance is less than 1% by weight, improvement in scratch resistance is insignificant.

The flow enhancer (F) improves the appearance quality of the product during injection by improving the flowability of the polypropylene. The flow enhancer (F) improves the appearance of the product at the time of injection, and comprises N, N'-ethylene bis- N'-Ethylene Bis-Stearamide) is preferably used.

[Chemical Formula 1]

The flow enhancer is preferably used in an amount of 1 to 5% by weight based on the total weight of the polypropylene resin composition. If the amount of the flow enhancer is less than 1 wt%, the fluidity may not be sufficient. If the flow enhancer is more than 5 wt%, the mechanical strength may be lowered.

INDUSTRIAL APPLICABILITY As described above, the polypropylene resin composition of the present invention satisfactorily satisfies the mechanical properties such as scratch resistance and the like by controlling the proper mixing of the polypropylene resin, the modified polypropylene resin, the long fiber, the scratch agent and the flow promoter A tailgate inner panel having excellent appearance can be manufactured.

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.

Examples 1 to 3 and Comparative Examples 1 to 13

The polypropylene resin composition according to the composition and content of the following Table 1 was mixed, extruded using a twin-screw extruder and a draw-out machine, and injection molded to prepare a physical property specimen.

Polypropylene resin composition division
(unit:
weight%) (A) (B) (C) (D) (E) Sum Propylene homopolymer ¹⁾ Propylene homopolymer ²⁾ Propylene-ethylene
Copolymer ^{3 )} Propylene-
Ethylene
Copolymer ^{4 )} Modified polypropylene ⁵⁾ Jangyuri fiber ⁶⁾ Jangyuri fiber ⁷⁾ My scratch ^{8 )} Flow
Enhancer ^{9 )} Example 1 10 40 5 40 2 3 100 Example 2 20 30 5 40 2 3 100 Example 3 10 30 5 50 2 3 100 Comparative Example 1 10 41.5 5 40 0.5 3 100 Comparative Example 2 10 35 5 40 7 3 100 Comparative Example 3 10 42.5 5 40 2 0.5 100 Comparative Example 4 10 36 5 40 2 7 100 Comparative Example 5 10 40 5 40 2 3 100 Comparative Example 6 10 40 5 40 2 3 100 Comparative Example 7 20 32.1 5 40 2 0.9 100 Comparative Example 8 20 27.9 5 40 2 5.1 100 Comparative Example 9 10 31.1 5 50 0.9 3 100 Comparative Example 10 10 26.9 5 50 5.1 3 100 Comparative Example 11 5 5 5 80 2 3 100 Comparative Example 12 87 5 3 2 3 100 Comparative Example 13 87 5 3 2 3 100 1) Propylene homopolymer: melt index 20 g / 10 min
2) Propylene homopolymer: melt index 5 g / 10 min
3) Propylene-ethylene copolymer: melt index 1000 g / 10 min
4) Propylene-ethylene copolymer: melt index 50 g / 10 min
5) Modified polypropylene: A resin grafted with 1.0 wt% of maleic anhydride to a polypropylene polymer.
6) long fiber: fiberglass having a diameter of 17 μm and a length of 10 mm
7) long fiber: fiberglass having a diameter of 17 탆 and a length of 2 mm
8) Scratch agent: 20% by weight of a monomer unit containing an amine group in the olefin-acrylate copolymer component (trade name: NOFALLOY series)
9) Flow enhancer: N, N'-Ethylene Bis-Stearamide

Experimental Example 1: Measurement of physical properties

The properties of the specimens prepared in Examples 1 to 3 and Comparative Examples 1 to 13 were measured by the following test methods and the results are shown in Table 2 below.

(1) Tensile strength: Measured according to ASTM D 638.

(2) Flexural strength and flexural modulus: Measured according to ASTM D790.

(3) IZOD impact strength: measured according to ASTM D256 for? "Notched condition and room temperature (23) temperature condition.

(4) Heat deformation temperature: Measured according to ASTM D648.

(5) Scratch resistance: Using a Erickson apparatus, scratches are made in a grid pattern of 20 or more at intervals of 2 mm, and the L value is calculated by measuring the L value before and after the scratch evaluation. The measuring device is measured using a d / 8 ° spin sphere colorimeter. The L value is a value representing the lightness in the color coordinates in CIELAB. L = 100 (white) and L = 0 (black).

(6) Flowability: Measured according to ASTM D3123.

(7) Appearance: When the appearance was visually observed, the degree of exposure of the glass fiber to the appearance was extremely small, and the state was evaluated as "O", and the state of not good as "X".

Physical property measurement result Properties Seal
burglar
(MPa) curve
burglar
(MPa) curve
Modulus of elasticity
(MPa) Izod
Impact strength
(J / m) Thermal deformation
Temperature
(° C) Scratch resistance
(DELTA L) liquidity
(Mm) Exterior
(? E) Example 1 150 180 7500 250 160 1.1 55 O Example 2 153 185 7700 240 160 1.1 52 O
Example 3 160 191 9500 280 160 1.0 50 O Comparative Example 1 152 181 7600 253 160 2.5 56 O Comparative Example 2 135 160 7000 210 158 0.9 54 O Comparative Example 3 151 181 7550 252 160 1.1 40 X Comparative Example 4 110 140 6500 175 155 1.2 70 O Comparative Example 5 135 165 6500 70 157 2.2 50 O Comparative Example 6 121 151 7350 205 160 1.0 25 X Comparative Example 7 155 187 7800 242 160 1.1 38 X Comparative Example 8 115 145 6800 160 154 1.2 54 O Comparative Example 9 161 190 9550 281 160 2.0 48 O Comparative Example 10 140 169 8800 180 160 1.0 51 O Comparative Example 11 182 215 15000 300 160 1.0 10 X Comparative Example 12 21 25 2000 50 90 1.1 220 O Comparative Example 13 23 27 2500 60 91 1.2 75 O

When the content of the scratch agent is less than the content of the scratch agent in Example 1, Comparative Examples 1 and 2, Example 3 and Comparative Examples 9 and 10, the scratch resistance becomes insufficient, and the content of the scratch agent becomes The mechanical properties are deteriorated.

In addition, if the content of the flow enhancer is less than the content of the flow enhancer through Example 1, Comparative Examples 3 and 4, and Example 2 and Comparative Examples 7 and 8, the appearance of injection due to insufficient flowability can not be satisfied. .

In addition, in Comparative Example 5, the appearance was improved but the mechanical properties were deteriorated when the length of the long fibers was too short. In Comparative Example 6, when the flow index of the propylene homopolymer and the propylene-ethylene copolymer was too low, It can be seen that the shortage did not satisfy the appearance.

In addition, it can be seen from Comparative Example 11 that the content of the long fibers is too high to satisfy the appearance due to the lack of fluidity, and in Comparative Examples 12 and 13, the mechanical properties are deteriorated due to insufficient long fiber content.

Therefore, the composition of the present invention can provide a satisfactory mechanical property such as scratch resistance and the like by controlling the optimal blending of polypropylene resin, modified polypropylene resin, long fiber, scratch resistant agent and flow promoter, Can be usefully used for manufacturing gate inner panels.

Claims (7)

(A) 10 to 86% by weight of a polypropylene resin which is a mixture of at least one selected from the group consisting of a propylene homopolymer and a propylene-ethylene copolymer;
(B) 2 to 10% by weight of a modified polypropylene resin;
(C) 10 to 70% by weight of long fiber;
(D) from 1 to 5% by weight of scratches; And
(E) 1 to 5 wt% of a flow enhancer;
/ RTI >
The propylene homopolymer in the polypropylene resin (A) has a melt index (MeltIndex) of 10 to 25 g / 10 min at 230 캜, a propylene-ethylene copolymer at 100 to 2,000 g / 10 min at 230 캜,
The long fibers (C) have an average diameter of 10 to 30 탆 and a length of 6 to 16 mm,
Wherein the flow enhancer (E) is N, N'-Ethylene Bis-Stearamide. 10. The polypropylene resin composition for a tailgate inner panel according to claim 1, wherein the flow enhancer (E) is N, N'-Ethylene Bis-Stearamide.
delete The polypropylene resin composition according to claim 1, wherein the modified polypropylene resin (B) is obtained by grafting an unsaturated carboxylic acid or a derivative thereof to a polypropylene polymer in an amount of 0.5 to 5% by weight and has a weight average molecular weight of 100 to 5,000 g / mol Wherein the polypropylene resin composition is a polypropylene resin composition for a tailgate inner panel.
delete The method according to claim 1, wherein the scratch agent (D) has a melt flow index of 13 to 15 g / 10 min (230 캜, 10 kg) and a melting point of 92 to 95 캜, Wherein the olefin-acrylate-based copolymer is a pellet-type olefin-acrylate copolymer having 18 to 24 wt% of a monomer unit contained in the polypropylene resin composition for a tailgate inner panel.
delete A tailgate inner panel formed from the polypropylene resin composition of any one of claims 1, 3, and 5.

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