KR101483914B1 - Polypropylene Resine Composition - Google Patents

Abstract

The present invention relates to a polypropylene resin composition and, more specifically, to a polypropylene resin composition which can not only obtain properties that basic components demand, but also reduce the weight since the weight is low, and has low linear expansion according to temperature variation, thereby easily used for interior and exterior materials for a vehicle. According to the present invention, provided is a polypropylene resin composition comprising: 40-97 wt% of a high crystalline polypropylene resin in which an isotactic peptide fraction is more than or equal to 96% by a C13-NMR method; 1-40 wt% of a rubber composition; 1-10 wt% of whisker; and 1-10 wt% of fine talc in which apparent density is less than or equal to 0.8 g/cm^3 and average particle size is less than or equal to 3 μm.

Description

Polypropylene Resin Composition < RTI ID = 0.0 >

The present invention relates to a polypropylene resin composition, which can reduce weight due to its low weight while maintaining the characteristics required of basic components, and has a low linear expansion due to temperature changes. Particularly, To a resin composition.

Recently, in the automotive industry, the development of new products is accelerating with the aim of improving the fuel efficiency through environmental friendliness and light weight. Reflecting this fact, polypropylene composite materials, which are the most widely used plastics used for automobiles, have become important to develop products with a lower specific gravity while having a lower specific gravity. Ultimately, it has been attempted to develop a product having excellent mechanical properties of polypropylene itself, which is a starting material of a polypropylene composite material, and the functional properties of various organic and inorganic fillers corresponding to the sub-materials have also been improved. As a result, we have developed a polypropylene composite material with high quality, and have made efforts to reduce the weight of automobiles by using low specific gravity polypropylene resin which is similar in performance to existing materials but weight is reduced. Particularly, (CLTE: coefficient of thermal expansion (CLTE), which minimizes the change in dimension due to temperature change, as well as low specific gravity, is used for the exterior material, bumper, side molding, side sill molding, of Linear Thermal Expansion), material development is an important factor.

The main research items of these polypropylene composites for automobiles are to maintain the basic characteristics of the parts in use while achieving lighter weight. In addition to securing the functions of simple parts, it contributes to the improvement of the performance of additional vehicles such as fuel efficiency improvement will be. The composition of the polypropylene resin composition generally used is composed of polypropylene as a basic component and an oil, an inorganic filler for reinforcing rigidity according to the use, and an elastomer for improving some impact properties. And the optimized composition is obtained by controlling the content according to the use and characteristics of the component or matching the components according to the characteristics.

The rigidity and the impact characteristics are balanced by the parts of the automobile and the exterior material, and the inorganic filler having a complicated product structure and various resin compositions regulating the rubber component content are applied. Therefore, as the types of polypropylene resin compositions used for interior and exterior materials are increased, the related productivity improvement such as part molding conditions and mold technology has appeared as major problems, and the products tend to be complicated and diverse. In particular, in the case of the exterior material, the appearance of the exterior of the design is increased, and the demand for a material having excellent dimensional stability capable of digesting various designs is becoming more and more urgent.

The present invention can be applied to all external parts such as bumper, side molding, garnish, side sill molding of an automobile exterior material, and can be applied to an instrument panel of an interior material, There is provided a resin composition excellent in low specific gravity and low linear expansion property that secures the rigidity required by a component while exhibiting high impact properties by optimizing the additional inorganic filler and rubber component content in the case of a resin composition requiring high impact such as will be.

In order to achieve the above object, the present invention provides a high-crystalline polypropylene resin (HIPP) having an isotactic peptad fraction of 96% or more according to the C-NMR method; 1 to 40% by weight of a rubber component; 1 to 10% by weight of whiskers; And 1 to 10% by weight of fine talc.

INDUSTRIAL APPLICABILITY According to the present invention, a polypropylene resin composition excellent in low specific gravity and low linear expansion property exhibits balanced component properties of rigidity and impact properties while securing stable dimensional stability, and excellent in injection moldability and surface appearance characteristics, Can be used for exterior materials.

As described above for the development of a polypropylene resin composition for automotive exterior materials with low specific gravity and low linear expansion characteristics, the present invention provides a polypropylene resin composition for automobile exterior materials having low specific gravity and low linear expansion characteristics, which is prepared by using highly crystalline polypropylene having excellent mechanical properties as a basic raw material, And the rubber content was optimized and optimized to improve the impact characteristics required for the exterior material, using the whisker with high whisker and the fine talc with the improved rigidity.

In addition, the polypropylene used has a wide molecular weight distribution, so that the viscosity is lowered according to the shear force to the processing region, which not only enhances the appearance of the product, but also has advantages of easy molding and processing.

The present invention relates to a polypropylene resin having a high crystallinity and a relatively wide molecular weight distribution and having excellent moldability and rigidity. In order to secure additional rigidity, whiskers having small aspect ratios and small amounts of fine talc The basic concept is to use a rubber composition to satisfy the final impact characteristics and to satisfy the final component requirement characteristics.

The polypropylene resin used in the present invention is a highly crystalline polypropylene resin, preferably a polypropylene resin having a high isotacticity index, more preferably a polypropylene resin of a highly crystalline block copolymer. For example, a high crystalline polypropylene resin (HIPP) having an isotactic peptid fraction of 96% or more by the C ¹³ -NMR method is used in an amount of 40 to 97% by weight based on the total polypropylene resin composition. When the content is less than 40% by weight, the properties of the entire polypropylene deteriorate and it is difficult to exert its function. When the content is more than 97% by weight, the content of the other components is undesirably lowered.

The highly crystalline polypropylene resin preferably has a polydispersity index (PI) of 5 or more. If the PI is less than 5, the molecular weight distribution is basically narrow. Even though there are not many polymers having a large absolute molecular weight, the polymer having a similar molecular weight becomes larger in quantity, resulting in a decrease in molding characteristics during processing, The appearance defect phenomenon is easily generated.

The highly crystalline polypropylene resin has a melt index of 1 to 110 g / 10 min (ASTM D 1238, 230 캜, 2.16 Kg), and isotactic polypropylene, propylene-ethylene comonomer, propylene 1-butene copolymer, propylene 1 hexene copolymer , Propylene 4-methyl-1-pentene copolymer, and other small amounts of other alpha olefin-propylene copolymers, random copolymers, or mixtures thereof.

The present invention contains a rubber component for proper flexibility and rigidity balance of the composition. The rubber component is preferably at least one member selected from the group consisting of an amorphous ethylene? -Olefin copolymer and a styrene-based thermoplastic elastomer. By this, it is possible to obtain suitable flexibility and to improve impact strength characteristics such as resistance to low- .

Examples of the amorphous? -Olefin copolymer include propylene, butene 1, pentene 1, hexane 1, octene 1, 4-methylpentene 1 and heptene 1 as the? As the styrenic thermoplastic elastomer, SEBS (styrene-ethylene-butene-styrene copolymer) is mainly used.

The rubber component used in the present invention is exemplified by the rubber component of an ethylene-octene copolymer and an ethylene-butene copolymer, and the content thereof can be 1 to 40% by weight based on the total composition. If it is less than 1% by weight, the effect of alleviating the impact due to the rubber component is insignificant, and if it exceeds 40% by weight, the ductility is strengthened, which is not preferable due to lack of rigidity as a component.

In the present invention, whiskers are contained in an amount of 1 to 10% by weight in order to exhibit more balanced bending stiffness and impact strength. The higher the aspect ratio of the whisker is, the higher the value of the stiffness due to the orientation effect is, and the smaller the amount of the whisker is, the easier it is to satisfy the component demand characteristics. However, when it is 20 or less, the discrimination power is reduced in improvement of the rigidity with the inorganic filler such as talc, which is widely used in the past, and the average length is preferably 5 to 100 μm or less and 5 μm or less on average. When the length is less than 5 占 퐉 or the diameter is larger than 5 占 퐉, it is difficult to expect an improvement in rigidity due to the effect of the aspect ratio, so it is important to select an inorganic filler having an appropriate aspect ratio.

The polypropylene resin composition of the present invention contains fine talc for the purpose of reinforcing rigidity. The fine talc preferably has an apparent density of 0.8 g / cm 3 or less and an average particle size of 3.0 탆 or less. In the case of micro-talc having a small aspect ratio, the absolute size is predominant in improving the stiffness. Therefore, when the apparent density exceeds 0.8 g / cm 3, the specific surface area becomes large and the improvement of the rigidity is limited. When the particle size exceeds 3.0 탆 Similarly, the interfacial area between the inorganic material and the organic material in the polymer is reduced, which reduces the overall stiffness of the organic material.

In addition to the above-mentioned components, coloring agents that can be added in the present invention include inorganic pigments and organic pigments. Examples of the inorganic pigments include aluminum flakes, aluminum powder, aluminum foil, zinc powder, bronze powder, Zinc oxide, zinc sulphide, chrome yellow, barium yellow, navy blue, cobalt blue, cobalt green and carbon black. Examples of the organic pigments include Watching Red, Permanent Red, Palladium Red, Tall Ginger, Benzidine Elo, Phthalocyanine Green and the like.

The composition of the present invention may further contain various additives and reinforcing agents such as a long-term heat stabilizer, a weather stabilizer, an antistatic agent, a lubricant, a slip agent, a nucleating agent, a flame retardant, It is possible.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

In the present invention, in principle, a test piece according to the standard test is used, and the test piece is manufactured by injection molding. In addition, the kneading extruder is manufactured by pre-kneading by measuring the amount of each component in a diameter of 32 mm (L / D, 40: 1) manufactured by SM Platech. All of the examples and comparative examples were dried in an oven at 90 캜 for 3 hours in consideration of attenuation of physical properties due to moisture absorption in the composition. The composition was injected using a Si180-III (mold force = 180 tons) injection machine manufactured by Toyo Co., Ltd. The injection temperature was 180/200/200/210/210 占 폚 in the order of nozzle in the feed hopper, Was molded from 60 to 100 bar, and molded articles for physical property measurement and test pieces for appearance test evaluation were prepared.

The components and characteristics of the materials used in this example and comparative examples are shown in Tables 1, 2, and 3. Table 1 shows the characteristics of polypropylene having a high crystallinity and a broad molecular weight distribution as a base resin to be used as a base resin composition. Table 2 shows rubber components. Table 3 shows specifications of inorganic fillers used. The resin composition blended from the combination of these components was pelletized by using the above-mentioned co-directional twin-screw extruder, which is one of the conventional methods, and was then made into an injection molded specimen and its specific gravity and coefficient of linear expansion were measured. The extruded pellets were dried and dried at 90 ° C for 3 hours to prevent water contamination. Injection molding specimens were prepared and the coefficient of linear expansion was measured after standing at room temperature for more than 48 hours.

Sample No. The melt index [g / 10 min]
(230 DEG C, 2.16 Kg) PI (230 DEG C) Weight average molecular weight [g / mol] Isotactic Peptid Fraction ** PP H-1 11 3.8 230,000 97.2 PP H-2 41 3.9 180,000 96.1 PP B-1 22 3.7 210,000 96.4 PP B-2 40 4.1 190,000 96.8 PP B-3 46 5.8 185,000 96.9 PP B-4 105 3.8 150,000 96.5

Sample No. Flow Index [g / 10 min]
(190 DEG C, 2.16 Kg) Density [Kgf / cm ³ ] etc Rub-1 1.0 0.857 C2-C8 copolymer elastomer Rub-2 5.0 0.868 C2-C8 copolymer elastomer Rub-3 0.5 0.862 C2-C6 copolymer elastomer

Sample No. Sample classification Size [탆] Filler-1 Talc Average diameter: 3 ~ 6 Filler-2 Fine talc * Average diameter: 0.65 Filler-3 Whisker ** Average length: 15,
Average diameter: 0.5

Fine talc: Apparent density = 0.55 g / cm3

** Whisker: Aspect Ratio = 30

Tables 4 and 5 show the physical properties, the coefficient of linear expansion, and the appearance performance evaluation of the resin composition prepared from the raw material described above.

Example
Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 PP H-1 - - 10 - 10 10 PP H-2 - - - 10 - - PP B-1 27 30 17 15 - - PP B-2 37 32 35 35 29 29 PP B-3 - - - - 28 28 PP B-4 - - - - - -

Example
Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Rub-1 10 10 11 16 16 Rub-2 10 22 10 - - Rub-3 11 8 8 Filler-1 16 16 18 18 - - Filler-2 - - - - 6 3 Filler-3 - - - - 3 6 Nucleating agent - - - - 0.2 0.2 The melt index [g / 10 min]
(230 DEG C, 2.16 Kg) 25.1 26.7 20.5 22.5 14.9 15.2 Tensile strength [Kgf / cm ² ] 200 205 212 210 198 195 Flexural modulus [Kgf / cm ² ] 15,800 16,500 17,800 16,950 15,300 14,900 Izod impact strength (-30 ° C)
[Kgfcm / cm] 5.0 5.1 4.8 4.5 7.0 7.8 Heat deformation temperature [℃] 108 109 114 115 98 100 Density 1.01 1.00 1.03 1.02 0.944 0.949 CLTE MD (-30 to 30 ° C) 7.5 7.3 7.8 8.1 6.4 6.3 CLTE TD (-30 to 30 ° C) 8.9 9.1 8.7 9.9 5.9 6.1 Flowmark occurrence rate [%] 68 65 69 72 28 25

* Flow mark generation rate: Spiral specimens with a width of about 2.5 cm and a thickness of about 2 cm were injected at the same temperature and pressure, and the total flow length was measured. The length of the flow mark was measured ) And measured by the following formula.

Example
Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 3 Example 4 PP - - 10 - 20 10 PP - - - 10 - - PP 27 30 17 15 - - PP 37 32 35 35 - 10 PP B-3 - - - - 47 37 PP B-4 - - - - - 10

Example
Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 3 Example 4 Rub-1 10 10 11 - - Rub-2 10 22 10 25 13 Rub-3 - - - 11 - 10 Filler-1 16 16 18 18 - - Filler-2 - - - - 7 6 * Filler-3 - - - - One 4 Nucleating agent - - - - 0.2 - The melt index [g / 10 min]
(230 DEG C, 2.16 Kg) 25.1 26.7 20.5 22.5 25.1 21.0 Tensile strength [Kgf / cm ² ] 200 205 212 210 214 190 Flexural modulus [Kgf / cm ² ] 15,800 16,500 17,800 16,950 20,850 18,900 Izod impact strength (-30 ° C)
[Kgfcm / cm] 5.0 5.1 4.8 4.5 4.9 6.1 Heat deformation temperature [℃] 108 109 114 115 124 109 Density 1.01 1.00 1.03 1.02 0.936 0.949 CLTE MD (-30 to 30 ° C) 7.5 7.3 7.8 8.1 5.6 6.0 CLTE TD (-30 to 30 ° C) 8.9 9.1 8.7 9.9 5.4 6.1 Flowmark occurrence rate [%] 68 65 69 72 19 22

* Example 4 Filler-2 is fed by extruder by side feeding

As shown in [Table 5] and [Table 6], in order to balance the stiffness and impact characteristics of the resin as in Comparative Examples 1 to 4 of conventional automotive exterior materials, the specific gravity is about 1.0 or more and the coefficient of linear expansion is 7 to 8 And 60% of the flow mark, which is an appearance evaluation index, is generated, which is a limit to be used for painting. However, in Examples 1 and 2 of Table 5, the specific gravity is lowered by about 5%, and the coefficient of linear expansion is lowered, but the improvement of the dimensional stability especially in the TD direction is remarkably improved. In addition, the flow mark, which is an external appearance evaluation index, is lower than half of the standard material, and it can be applied to the non-painted specification in addition to the painting specification. In the case of the specific gravity, considering the fact that the molding flow characteristics are good during the actual injection, the weight reduction over the specific gravity difference can be expected. In Examples 3 and 4 of [Table 6] and [Table 7], the rigidity is further improved and the coefficient of linear expansion is lowered compared with Examples 1 and 2, and the rigidity is improved while ensuring the dimensional stability of the product. In other words, while securing the dimensional stability of the parts, the specific gravity is reduced and the weight can be reduced, and the rigidity is also improved, which is advantageous in terms of parts handling. Therefore, when the material of the existing external part is replaced with the material of the present invention, the product can be handed easily, the dimensional stability after the molding is secured, and the product can maintain the same quality as other parts characteristics such as impact resistance and appearance characteristics can do.

Claims (7)

40 to 97% by weight of a highly crystalline polypropylene resin having an isotactic peptad fraction of 96% or more by the C ¹³ -NMR method;
1 to 40% by weight of a rubber component;
1 to 10% by weight of whiskers; And
1 to 10% by weight of fine talc having an apparent density of 0.8 g / cm 3 or less and an average particle size of less than 3 탆,
Wherein the polypropylene resin composition further comprises a nucleating agent for stiffening addition. The polypropylene resin composition according to claim 1, wherein the highly crystalline polypropylene resin has a polydispersity index (PI) of 5 or more. The method of claim 1, wherein the highly crystalline polypropylene resin has a melt index of 1 to 110 g / 10 min (ASTM D 1238, 230 캜 / 2.16 kg), isotactic polypropylene, propylene- ethylene comonomer, propylene 1-butene copolymer, propylene 1 hexene copolymer, and propylene 4 methyl 1 pentene copolymer, a copolymer thereof with propylene, a random copolymer, or a mixture thereof. The polypropylene resin composition according to claim 1, wherein the rubber component is ethylene-octadiene, ethylene-butadiene or a mixture thereof. The polypropylene resin composition according to claim 1, wherein the whisker has an aspect ratio of 20 or more and an average length of 5 to 100 占 퐉 and an average diameter of 5 占 퐉 or less. delete The polypropylene resin composition according to claim 1, wherein the resin composition further comprises a colorant in an amount of 1 to 10% by weight based on the total composition.