KR101417114B1 - Polypropylene/clay Nanocomposites for the Non-Paint Exterior Automotive Parts and Preparing method thereof - Google Patents

Abstract

The present invention 1 ~ 20 g / _10, in more detail described, organophilic clay, a maleic anhydride graft polypropylene, a melt index (MI) related to a car unpainted exterior parts polypropylene / clay nano-composite material and a method for (A) a masterbatch containing a polypropylene resin in an amount of 1 to 20 _minutes ; (B) a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} ; (c) ultraviolet stabilizer; And (d) a heat stabilizer. The present invention relates to polypropylene / clay nanocomposites for automotive unpainted exterior parts. The nanocomposite of the present invention is obtained by melt-compounding the organic clay, polypropylene grafted with maleic anhydride and a polypropylene copolymer having a melt index (MI) of 1 to 20 g / _{10 min} to prepare a master batch, And a polypropylene copolymer, an ultraviolet stabilizer and a heat stabilizer at an optimum ratio. The nanocomposite of the present invention is excellent in low-temperature impact resistance, weld line strength and weatherability, has excellent appearance quality of a molded product, can be cost-reduced through elimination of a coating process, is light in weight, Molding, and roof rack covers.

Unpainted, polypropylene, nanocomposite, maleic anhydride, organic clay

Description

TECHNICAL FIELD [0001] The present invention relates to a polypropylene / clay nanocomposite for exterior parts of automobile mats and a method for manufacturing the same,

(A) a masterbatch containing an organic clay, polypropylene grafted with maleic anhydride and a polypropylene resin having a melt index (MI) of 1 to 20 g / _{10 min} ; (B) a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} ; (c) ultraviolet stabilizer; And (d) a heat stabilizer. The present invention relates to a polypropylene / clay nanocomposite for automotive unpainted exterior parts, and a method of manufacturing the same.

Polypropylene composites are not only excellent in stiffness and impact resistance but also excellent in cost competitiveness, and are widely used as components for engine chassis as well as for interior and exterior parts for automobiles. Polypropylene has a problem of high molding shrinkage. In order to secure the dimensional stability and rigidity of parts, an inorganic additive such as talc or glass fiber is mixed with polypropylene to prepare a composite material depending on the application. However, since such an inorganic additive has a high specific gravity, it not only lowers the weight-reducing effect of polypropylene but also has low weather resistance and low-temperature impact resistance and weld line strength due to distribution of inorganic additives of several tens of microns in size on the surface of the composite There is a problem of deterioration.

Many polypropylene / clay nanocomposites have been studied for the weight reduction of such polypropylene composites. (H.-S. Lee, et al, Polymer, 46, 11673-11689, 2005; DHKim, et al, Polymer, 48, 5960-5978, 2007) A polypropylene / clay nanocomposite (Korean Patent No. 10-0792889) improved in clay dispersibility and a polypropylene / clay nanocomposite (Korean Patent No. 10-0706422) capable of improving dimensional stability are known, There is a problem that the mechanical properties are insufficient as the material of the external part.

Most of the conventional automotive plastic exterior parts have been used after the coating process. Therefore, the weather resistance of the resin itself and the appearance quality of parts such as weld lines were excluded from the examination items because the resin itself was not directly exposed to the external environment. However, recently, price competitiveness of automobiles has become a hot topic, and it is required to remove surface coating on some parts of automobile exterior parts. Therefore, polypropylene / clay for exterior parts of automobile unpainted parts having excellent weather resistance, low temperature impact resistance, weld line strength and external appearance quality Development of nanocomposites is required.

The present inventors have made efforts to develop a polypropylene / clay nanocomposite suitable for use in automobile unpainted exterior parts. As a result, they have found that introduction of a polypropylene resin having a different melt index, introduction of a UV stabilizer and a heat stabilizer, It has been found that the flowability and weatherability of the composite material can be increased by optimizing the blending ratio, thereby completing the present invention. That is, the present invention provides a polypropylene / clay nanocomposite for automobile unpainted exterior parts and a method of manufacturing the same.

The present invention provides a polypropylene / clay nanocomposite for automobile unpainted exterior parts, which comprises an organic clay, a polypropylene grafted with maleic anhydride and a polypropylene having a melt index (MI) of 1 to 20 g / _{10 min} (A) a masterbatch comprising a resin; (B) a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} ; (c) ultraviolet stabilizer; And (d) a heat stabilizer.

The present invention is a, organophilic clay, maleic anhydride is grafted polypropylene, melt index (MI) 1 ~ 20 g / 10 _bun of masterbatch to poly melt compounding the propylene resin relates to a method for producing the nanocomposite Producing; And 200 to 900 parts by weight of a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} with respect to 100 parts by weight of the masterbatch, 0.2 to 5 parts by weight of a UV stabilizer and 0.1 to 4 parts by weight of a heat stabilizer And a second step.

The polypropylene / clay nanocomposite of the present invention is excellent in mechanical properties such as weatherability, low-temperature impact resistance and weld line strength because of its excellent flowability, and is excellent in light weight and weatherability of automotive exterior parts exposed to the external environment .

The present invention described above is described in detail as follows.

The polypropylene / clay nanocomposite of the present invention will be described.

(A) a masterbatch containing an organoclay clay, polypropylene grafted with maleic anhydride and a polypropylene resin with a melt index (MI) of 1 to 20 g / _{10 min} ; (B) a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} ; (c) ultraviolet stabilizer; And (d) a heat stabilizer. Each of the above-mentioned composition materials will be specifically described.

[Master batch]

The organizing clay, which is one of the components of the masterbatch, is selected from the group consisting of montmorillonite, hectorite, saponite, sauconite, vermiculite, magadiite, , Kenyaite, kaolinite, and thuringite, or two or more inorganic clays selected from the group consisting of kaolinite, kaolinite, and thuringite by a mineralizing agent. Here, the inorganic clay may have a layered structure having a particle size of 0.1 to 100 占 퐉 and capable of nanodispersion in the polymer.

And the above-mentioned hydrophilizing agent may be an alkylammonium organizing agent of C ₁₀ to C ₁₈ , preferably octylammonium, decylammonium, dodecylammonium, hexadecylammonium, octadecylammonium, dimethylhydrogenated tallowammonium and stearyl Ammonium, or two or more species selected from the group consisting of ammonium chloride and ammonium chloride. The organic clay can be modified by modifying the surface of the inorganic clay by using such a mineralizing agent. If the alkylammonium organizing agent has a carbon number of less than 10, the dispersion of the clay in the final composite may be insufficient. If the carbon number is more than 18, the clay surface organizing efficiency may decrease. It is preferable to use an alkylammonium organizing agent having a carbon number within the above range.

The polypropylene grafted with maleic anhydride (hereinafter referred to as "PP-g-MA") which is one of the components in the master batch can have a melt index (MI) of 5 to 100 g / _{10 min} , And the PP-g-MA having a melt index of less than 5 g / _{10 min} may cause a problem that the impact strength of the final composite material is decreased. When the material having a melt index of more than 100 g / _{10 min} is used, PP-g-MA having an average molecular weight within the above range may be used. The PP-g-MA may be grafted with 0.1 to 4% by weight of maleic anhydride relative to the total weight of PP-g-MA. When grafted with less than 0.1% by weight of maleic anhydride is used, And a graft exceeding 4% by weight may cause difficulty in commercial production or a problem that the molecular weight of PP-g-MA becomes small and the impact strength of the final composite decreases.

Another containing component of the master batch of the polypropylene resin (hereinafter referred to as "PP resin") is to use the melt index (MI) of 1 ~ 20 g / _{10 min,} a melt index of 1 g / _{10 bun} less than A problem that the organic clay dispersion becomes insufficient can be caused. When the content of the organic clay is more than 20 g / _{10 min} , there is a problem that the melt shearing force applied to the organic clay is not sufficient. It is preferable to use a PP copolymer having a melt index in the range.

The PP resin having a melt index (MI) of 1 to 20 g / _{10 min}

Propylene homopolymers;

A random copolymer obtained by copolymerizing 80 to 90 mol% of propylene monolate with 10 to 20 mol% of a monomer selected from ethylene, butylene and octene; And

A block copolymer obtained by blending 85 to 95 mol% of propylene homopolymer and 5 to 15 mol% of ethylene-propylene-rubber; Or a mixture of two or more of them may be used.

The composition of the master batch of the present invention contains an organophilic clay 40 to 60% by weight, PP-g-MA 30 - 50% by weight and a melt index (MI) 1 ~ a PP resin ₁₀ 20 g / 10 _min to 30% by weight If the organizing clay is less than 40% by weight based on the total weight of the master batch, it may cause an uneconomical problem due to an increase in the amount of the master batch used in the final composite. If the organic clay exceeds 60% by weight, If the PP-g-MA content is less than 30% by weight, the dispersion effect of the organic clay may be deteriorated. If the PP-g-MA content exceeds 50% by weight, the mechanical properties of the nanocomposite may be deteriorated. It is preferable to have a weight within the above range. The content of the PP resin is relatively determined depending on the contents of the organic clay and PP-g-MA. It is preferable to use the organic clay and the PP-g-MA in a weight ratio of 1: 0.5 to 1.5. If the organic clay is less than 1: 0.5, the dispersion effect of the nano-clay may be decreased. I can do it.

[PP resin]

The PP resin having a melt index (MI) of 15 to 35 g / _{10 min} , which is a constituent material of the present invention, may be used in an amount of 200 to 900 parts by weight based on 100 parts by weight of the masterbatch. When the amount is less than 200 parts by weight, An unexpected problem may arise due to poor properties or impact strength, or an increase in the amount of masterbatch in the final composite material, and when 900 parts by weight of the composite material is used, there is a possibility that the properties of the final composite material, such as rigidity and dimensional stability, Therefore, it is recommended to use within the above range. And the PP resin as to obtain a melt-flowability improving effect of the PP resin and are in use to be 15 ~ 35 g / _{10 bun} different melt index, which is the final composite material used in manufacturing the master batch, 15 g / ₁₀ less than _{a minute} The flowability of the resin during injection molding is low, and the appearance quality may be deteriorated due to the occurrence of weld lines and flow marks in the appearance of the gaseous body, and when it is used in an amount exceeding 35 g / _{10 min,} the chain tangle between the polymer chains is reduced, The impact strength of the composite material may be reduced.

The PP resin having the above-mentioned melt index of 15 to 35 g / _{10 min}

Propylene homopolymers;

A random copolymer obtained by copolymerizing 85 to 95 mol% of propylene monolate with 5 to 15 mol% of a monomer selected from ethylene, butylene and octene; And

A block copolymer obtained by blending 90 to 99 mol% of propylene homopolymer and 1 to 10 mol% of ethylene-propylene-rubber; Or a mixture of two or more of them may be used.

[UV stabilizer and heat stabilizer]

The ultraviolet light stabilizer may be used in an amount of 0.2 to 5 parts by weight, more preferably 0.5 to 3 parts by weight based on 100 parts by weight of the masterbatch, wherein the ultraviolet stabilizer is used in an amount of 0.2 part by weight By weight, sufficient weatherability can not be obtained. When the amount is more than 5 parts by weight, an uneconomical problem may arise due to an increase in the amount of use.

The ultraviolet light stabilizer may be an ultraviolet absorber (UVA) containing two or more species selected from among benzotriazole compounds and benzophenone compounds; And a hindered amine light stabilizer (HALS) at a weight ratio of 1: 0.5 ~ 2. When the weight ratio of the ultraviolet absorber to the light stabilizer is less than 1: 0.5, sufficient photo-oxidation prevention effect can not be obtained When the amount is more than 1: 2 parts by weight, discoloration due to the residual catalyst may easily occur. Therefore, it is preferable to mix the components so as to have a weight ratio within the above range. The ultraviolet absorber is more preferably selected from the group consisting of 2- (2'-hydroxymethylphenyl) benzotriazole, 2- [2'-hydroxy-3'5'bis ,? - dimethylbenzylphenyl) benzotriazole, 2- (2'-hydroxy-3'5'-di (2'-hydroxy-3'- t -butyl-5'-methylphenyl) -5-chlorobenzo [ triazole {2- (2'-hydroxy-3'- tert -butyl-5'-methylphenyl) -5-chlorobenzotriazole}, 2- (2'- hydroxy -3'5'- di - t - butylphenyl) -5-chlorobenzotriazole {2- (2'-hydroxy-3'5' -di- tert -butylphenyl) -5-chlorobenzotriazole}, 2- (2'- hydroxy -3'5'- di - t -amyl) -5-chlorobenzotriazole {2- (2'-hydroxy-3'5' -di- tert -amyl) benzotriazole}, 2- (2'- hydroxy -5'- t-octylphenyl) 2- (2'-Hydroxy-5'- tert- octylphenyl) benzotriazole}, And 2,2'-methylene bis [4- (1,1,3,3-tetramethylbutyl) -6- (2-N-benzotriazol- Benzotriazo-2-yl) phenol]}; or at least one benzotriazole-based compound selected from the group consisting of 4- (1,1,3,3-tetramethylbutyl) -6- And

2,4-Dihydroxybenzophenone, 2-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 5-sulfonic acid (2-hydroxy-4-methoxybenzophenone -5-sulfonic acid), 2- hydroxy -4- n - octoxybenzophenone (2-hydroxy-4- n -octoxybenzophenone ), 2- hydroxy-4 4-hydroxy-2-methoxyphenyl) methane {Bis (5-benzoyl-4-hydroxy- 2-methoxyphenyl) methane}, 2,2'-Dihydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy- A benzophenone-based compound or a benzophenone-based compound selected from the group consisting of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone};

, Or one containing two species can be used. The hindered amine light stabilizer is preferably bis- (2,2,6,6-tetramethyl-4-piperidinyl) sebacate {Bis- (2,2,6,6-tetramethyl-4- piperidinyl sebacate}, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate { -piperidinyl)} sebacate, bis- (1,2,2,6,6-pentamethyl-4-piperidinyl) -2- (3,5-t-butyl-4-hydroxybenzyl) -2 4-piperidinyl) -2- (3,5-di- tert -butyl-4-hydroxybenzyl) -2-n-butyl < / RTI & malonate}, tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) -1,2,3,4-butenetetracarboxylate {Tetr akis (2,2,6,6-tetramethyl -4-piperidinyl) -1,2,3,4-butanetetracarboxylate}, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) -1,2,3,4-butane Tetracarboxylate {Tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) -1,2,3,4-butane tetracarboxylate}, (mixed 2,2,6,6- Piperidinyl / tridecyl) -1,2,3,4-butene 4-butanetetracyl) -1,2,3,4-butane tetracarboxylate} (mixed 1,2,2,6,6-pentamethyl -4-piperidinyl / tridecyl) -1,2,3,4-butenetetracarboxylate {(Mixed 1,2,2,6,6-Pentamethyl-4-piperidinyl / , 3,4-butane tetracarboxylate}, poly [(1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine / , 6-tetramethyl-4-piperidinyl] imino] hexamethylene (2,2,6,6-tetramethyl-4-piperidinyl) imino [{Poly [(1,1,3,3- tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [2,2,6,6-tetramethyl-4-piperidinyl] imino] hexamethylene (2,2,6,6-tetramethyl- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine ) -4-hydroxy-2,2,6,6-tetramethylpiperidine} or two or more of them.

The heat stabilizer, which is one of the other constituent materials of the present invention, may be selected from the group consisting of a phenolic stabilizer, an epoxy stabilizer, a phosphite stabilizer, an ester stabilizer and a sulfur stabilizer. (2,4-di-t-butylphenyl) phosphite, diphenylmono (tridecyl) phosphite, phenyldi (tridecyl) phosphite, phenyl-bisphenol A pentaerythritol diphosphite , Tetraphenyldipropylene, glycol diphosphite and octadecyl-3- (3,5-di-t-butyl-4-hydrophenyl) -propionate may be used. The heat stabilizer may be used in an amount of 0.1 to 4 parts by weight based on 100 parts by weight of the masterbatch. If the amount of the heat stabilizer is less than 0.1 parts by weight, sufficient weather resistance may not be obtained. If the amount is more than 4 parts by weight, The residual heat stabilizer acts as an impurity and can act as an impurity. Therefore, it is preferable to use it within the above range.

Hereinafter, the production method of the polypropylene / clay nanocomposite of the present invention described above will be described in detail.

[Manufacturing method]

The process for producing a polypropylene / clay nanocomposite according to the present invention comprises

Preparing a master batch by melt compounding an organic clay, polypropylene grafted with maleic anhydride and a polypropylene resin having a melt index (MI) of 1 to 20 g / _{10 min} ; And

200 to 900 parts by weight of a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 minutes} , 0.2 to 5 parts by weight of an ultraviolet stabilizer and 0.1 to 4 parts by weight of a heat stabilizer, based on 100 parts by weight of the masterbatch, And a second step.

The kinds and the composition ratios of the above-mentioned composition materials are the same as those described above.

If you explain each step in detail,

In the first stage, the master batch organophilic clay 40 to 60% by weight, PP-g-MA 30 ~ 50% by weight and a melt index (MI) 1 ~ 20 g / 10 _bun of PP copolymer 10 to 30% by weight Is melt-compounded at a temperature of 170 ° C to 230 ° C. The organic clay and the PP-g-MA are preferably used in a weight ratio of 1: 0.5 to 1.5, as described above. The polypropylene may not sufficiently melt during the melt compounding at a temperature lower than 170 deg. C, and may not uniformly mix. When the temperature exceeds 230 deg. C, the polypropylene chain cutting may be accelerated. To be melt-compounded.

In the second step, the masterbatch prepared in the first step and the PP resin having a melt index (MI) of 15 to 35 g / _{10 min} , a UV stabilizer and a heat stabilizer are melt-compounded at a temperature of 170 to 230 ° C to complete the present invention do.

Such a polypropylene / clay nanocomposite of the present invention is very suitable for use in the manufacture of automobile plastic exterior parts.

Hereinafter, the present invention will be described more specifically by way of examples. However, the scope of the present invention is not limited by the following examples.

Examples 1 to 4 and Comparative Examples 1 to 3

Example 1

50 wt% of an organic clay (Nanocor, Nanomer 1.44P), 35 wt% of MA-g-PP having a maleic anhydride content of 2.6 wt% and a melt index of 10 g / _{10 min} and a random copolymer of propylene monomer and octene monomer (Dow, Engage 8842) having a melt index of 1 g / _{10 min} containing a co-polymer was melt-compounded at 185-190 ° C using a twin-screw extruder to prepare a master batch Respectively.

A melt index of 20 g / _{10 min} containing a block copolymer obtained by blending 95 mol% of propylene homopolymer and 5 mol% of ethylene-propylene-rubber with respect to 100 parts of the master batch (b) 400 parts by weight of a PP resin, 400 parts by weight of a light stabilizer bis- (2,2,6,6-tetramethyl-4-piperidinyl) sebacate { (2'-Hydroxy-3'5'-dibutylphenyl) benzotriazole}, which is an ultraviolet absorber, Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate as a heat stabilizer, butyl-4-hydroxypheny) -propionate} was added and melt-compounded at a temperature of 200 ° C to 210 ° C using a twin-screw extruder to prepare the polypropylene / clay nanocomposite of the present invention. article Ratio is shown in Table 1 below.

Example 2

The polypropylene / clay nanocomposite material was prepared in the same manner as in Example 1 except that 250 parts by weight of PP resin containing the block copolymer was used for 100 parts by weight of the master batch. Table 1 shows the results.

Example 3

A random copolymer and a propylene homopolymer having a melt index of 30 g / 10 minutes, which were prepared by copolymerizing 90 mol% propylene monomers and 10 mol% octene monomers, were prepared in the same manner as in Example 1 except that 95 mol% of ethylene- 3% by weight of a block copolymer having a melt index of 20 g / _{10 minutes} , which was prepared by blending 5 mol% of a polypropylene / clay The nanocomposites were prepared, and the composition materials and composition ratios used are shown in Table 1 below.

Example 4

A polypropylene / clay nanocomposite was prepared in the same manner as in Example 1 except that the weight ratio of the ultraviolet light absorber and the light stabilizer in the ultraviolet light stabilizer component was 1: 2. same.

Comparative Example 1

0.05 parts by weight of a light stabilizer, 0.05 parts by weight of an ultraviolet absorber and 0.08 parts by weight of a heat stabilizer were added in the same manner as in Example 1 to prepare a nanocomposite

Comparative Example 2

But the same manner as in Example 3, but compartment and MI is used for (b) PP resin of 8 g / _{10 bun} block copolymer type of polypropylene with MI 1 8 g / _{10 bun} of a random copolymer type Lt; / RTI >

Comparative Example 3

Except that the master batch was not used and the weight ratio of the PP resin mixed with the random copolymer to the block copolymer in the weight ratio of 2: 5 and the weight ratio of the talc (KCM-6300) 30 weight ratio , 0.3 parts by weight of an ultraviolet absorber, 0.3 parts by weight of a light stabilizer and 0.5 parts by weight of a heat stabilizer were mixed with 100 parts by weight of the PP resin and the talc mixture to melt and compound the mixture to prepare a composite material. Using the composite material, a side seal molding, which is an external component for unpainted automobiles currently manufactured and used by Hyundai Motor, was manufactured.

Experimental Example

Physical property measurement experiment

The properties of the specimens were evaluated with respect to five specimens for each test, and then the average values were taken. The specimens of the specimens were evaluated by the following methods using the automotive unpainted external component materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3, The results are shown in Table 2 below.

Specific gravity measurement experiment

ASTM D 792. < tb > < TABLE >

Weatherability experiment

The color difference (ΔE) before and after the test was measured using a colorimeter after irradiating 2500 kJ / ㎡ according to SAE J1960.

Weld line strength measurement experiment

The yield strength was measured by forming a mold with both ends of the TYPE1 specimen of ASTM D638 at both ends of the specimen and causing a weld in the middle of the tensile specimen. The test speed was 10 mm / _min .

Cotton impact strength

The energy value at the load peak was measured according to ASTM D3763. The thickness was measured at room temperature and low temperature (-30 ° C) using 2.5 mm flat plate specimens.

Part appearance evaluation

The uncoated side seal molding was injected into the mold, and the appearance defects of the weld line and the flow mark were evaluated as good and bad. The uncoated side seal molding produced using the composite material prepared in Example 1 is shown in FIG.

division importance Weatherability Weld line
burglar Cotton impact strength
(Room temperature) Cotton impact strength
(-30 ° C) Part appearance - ΔE (kgf / cm2) (J at max load) (J at max load) - Example 1 0.92 0.7 126 11.3 11.9 Great Example 2 0.93 0.62 134 10.2 10.8 Great Example 3 0.92 0.64 119 13.1 13.9 Great Example 4 0.92 0.4 127 11.4 12.3 Great Comparative Example 1 0.92 4.76 116 10.8 11.1 Great Comparative Example 2 1.12 1.46 89 8.9 5.7 Good Comparative Example 3 0.92 0.9 110 12.8 13.4 Bad

As shown in Table 2, when the values of the weather resistance (ΔE) in Examples 1 to 4 and Comparative Examples 1 and 2 are compared, it can be seen that the weather resistance of the material is excellent by the prescription of the weather resistance additive according to the present invention. It can be seen that the specific gravity of the polypropylene / clay nanocomposite according to the present invention in Examples 1 to 4 and Comparative Example 2 is lower than that of materials currently applied to unpainted exterior parts, which is advantageous for weight reduction of parts, It can be seen that the surface impact strength, particularly the impact strength at low temperature, is remarkably improved. It can also be seen that the material according to the invention having good melt flow of the material in Example 3 and Comparative Example 3 according to the present invention is excellent in the appearance quality of the parts.

As described above, the polypropylene / clay nanocomposite material is more uniformly dispersed in the polypropylene with a smaller amount of clay than the conventional polypropylene / clay nanocomposite material to improve the weld line strength and surface impact strength, As well as a polypropylene / clay nanocomposite having improved weather resistance can be produced.

The nanocomposite produced by the present invention can be applied to automobile exterior plastic parts such as a cowl top cover, a body side molding, a side seal molding and the like as a non-coated part in place of conventional materials for external parts, thereby contributing to cost reduction and weight reduction of parts .

FIG. 1 is a photograph of a unglazed side seal molding molded from a polypropylene / clay nanocomposite of Example 1 for evaluating the appearance of the parts of the experimental example. FIG.

Claims (9)

In the polypropylene / clay nanocomposite, (A) a masterbatch comprising an organic clay, a polypropylene grafted with maleic anhydride, and a polypropylene resin having a melt index (MI) of 1 to 20 g / _{10 min} ; (B) a polypropylene resin having a melt index (MI) of 15 to 35 g / _{10 min} ; (c) ultraviolet stabilizer; And (d) a heat stabilizer. The polypropylene / clay nanocomposite for automotive unpainted exterior parts. The method according to claim 1, (A) the master batch containing the organophilic clay of 40 to 60% by weight, 30 to 50% by weight and a melt index (MI) 1 ~ 20 g / 10 _bun 10 to 30% by weight of the polypropylene resin is maleic anhydride-grafted polypropylene A polypropylene / clay nanocomposite for automobile unpainted exterior parts. 3. The method according to claim 1 or 2, (a) 100 parts by weight of masterbatch (b) 200 to 900 parts by weight of a polypropylene resin; (c) 0.2-5 parts by weight of an ultraviolet stabilizer; And (d) 0.1 to 4 parts by weight of a heat stabilizer. The polypropylene / clay nanocomposite for automobile unpainted exterior parts. 3. The method according to claim 1 or 2, The organic clay The surface of the end clay or two or more kinds of inorganic clay selected from among montmorillonite, hectorite, saponite, saponite, vermiculite, magadiite, kenyaite, kaolinite and toliningite is mixed with C ₁₀ -C ₁₈ alkylammonium Polypropylene / clay nanocomposite for automobile unpainted exterior parts. The method according to claim 1, The polypropylene resin having a melt index of 1 to 20 g / _{10 min} Propylene homopolymers; A random copolymer obtained by copolymerizing 80 to 90 mol% of propylene monolate with 10 to 20 mol% of a monomer selected from ethylene, butylene and octene; And A block copolymer obtained by blending 85 to 95 mol% of propylene homopolymer and 5 to 15 mol% of ethylene-propylene-rubber; , Or a polypropylene / clay nanocomposite for automobile unpainted exterior parts. The method according to claim 1, The polypropylene resin (b) having a melt index of 15 to 35 g / _{10 min} Propylene homopolymers; A random copolymer obtained by copolymerizing 85 to 95 mol% of propylene monolate with 5 to 15 mol% of a monomer selected from ethylene, butylene and octene; And A block copolymer obtained by blending 90 to 99 mol% of propylene homopolymer and 1 to 10 mol% of ethylene-propylene-rubber; , Or a polypropylene / clay nanocomposite for automobile unpainted exterior parts. The method according to claim 1, Wherein the ultraviolet stabilizer is an ultraviolet absorber containing two or more species selected from benzotriazole compounds and benzophenone compounds; And Hindered amine light stabilizer; At a weight ratio of 1: 0.5 to 2, based on the total weight of the polypropylene / clay nanocomposite material. An automotive unpainted exterior part comprising the polypropylene / clay nanocomposite of claim 1, 2, 5, 6 or 7. Preparing a master batch by melt compounding an organic clay, polypropylene grafted with maleic anhydride and a polypropylene resin having a melt index (MI) of 1 to 20 g / _{10 min} ; And A second step of melt-compounding 200 to 900 parts by weight of a polypropylene resin having a melt index of 15 to 35 g / _{10 minutes} , 0.2 to 5 parts by weight of an ultraviolet stabilizer and 0.1 to 4 parts by weight of a heat stabilizer per 100 parts by weight of the master batch; Wherein the polypropylene / clay nanocomposite material is a polypropylene / clay nanocomposite material for automobile unpainted exterior parts.

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