KR20030056192A - Method for preparing polypropylene-based resin composition and the resin composition prepared thereby - Google Patents

Abstract

PURPOSE: Provided are a polypropylene-based resin composition having excellent rigidity, impact resistance, and heat resistance, as well as improved moldability, and a method for preparing the resin composition. CONSTITUTION: The method comprises the steps of (i) processing talc and an ethylene-propylene block copolymer with a twin-screw extruder or kneader to form a masterbatch, and (ii) directly introducing the talc master batch into an extruder connected to a polypropylene production line of ethylene-propylene block copolymer in line and continuously extruding the master batch. The talc masterbatch comprises 40-70 wt% of talc and the rest of ethylene-propylene block copolymer.

Description

Method for preparing polypropylene-based resin composition and its resin composition {Method for preparing polypropylene-based resin composition and the resin composition prepared thereby}

The present invention relates to a method for producing a polypropylene resin composition excellent in rigidity, impact resistance and heat resistance, and a resin composition thereof, and more particularly, after master batching of talc and ethylene-propylene block copolymer, which are inorganic fillers, Method for producing a polypropylene resin composition comprising the step of continuously extruded by direct talc master batch in-line in an extruder connected to a polypropylene production line producing an ethylene-propylene block copolymer It relates to a polypropylene resin composition produced by the method.

Since the olefin elastomer has the properties of elasticity and plastic at the same time, and has thermoplasticity, the molding and processing can be facilitated by using the same processing equipment as that used for ordinary thermoplastic olefin resin. Therefore, it has been widely used as an impact modifier of composite materials for plastic parts of automobiles.

However, the olefin-based elastomer has a problem of sharply lowering the rigidity and heat resistance when added in an excessive amount, in contrast to the effect of improving the impact resistance, and in particular, due to the high price, the material cost increases. In order to solve this problem, it is common to use a polypropylene resin blended with a variety of olefin elastomers (elastomer). However, the elastomer composition thus prepared has a disadvantage in that the melt flowability is poor due to the viscosity difference between the polypropylene resin and the elastomer, and as a result, the moldability is lowered.

To date, various studies have been conducted for the purpose of improving the moldability of the elastomeric composition. For example, in Japanese Patent No. 62-260846, an elastomer composition was prepared by blending ethylene-propylene random copolymer and styrene ethylene butadiene rubber, but the composition has good moldability but uses an amorphous random copolymer. There is a disadvantage that the physical properties are lowered.

On the other hand, in US Patent Nos. 4,212,787 and 4,247,652, polypropylene resin, polyethylene resin, ethylene-propylene rubber, polyisobutylene, and mineral oil are mixed with a chestnut mixer, and then the mixture is cut to form a crosslinking agent and a crosslinking aid. Disclosed is a method of kneading together in an extruder and then cutting the kneaded again and kneading together in a extruder with a polypropylene resin to produce an elastomeric composition. However, the composition prepared by the above method has good processability, physical properties, paintability, etc., but it is expensive to manufacture due to the complicated manufacturing process and various steps, and the liquid type mineral oil is uniformly mixed with other solid components. There is a problem that it is difficult to blend.

In addition, in US Patent No. 5,240,983 and European Patent No. 0409542A2, an elastomer composition was prepared by mixing polypropylene resin, ethylene-propylene rubber, ethylene-propylene diene rubber, organic silane, crosslinking agent and mineral oil. Similar to the methods of 4,212,787 and 4,247,652, liquid type mineral oils are used, which has the disadvantage that the blending between the components is difficult to achieve uniformly.

In contrast, Korean Patent Publication No. 1996-1009 discloses a polyolefin composition prepared by adding ethylene-propylene rubber as an impact modifier to a polypropylene block copolymer and adding fine talc as a rigidity and heat resistance reinforcing agent. However, the polyolefin composition improves impact resistance by adding an excess of ethylene-propylene rubber, while lowering rigidity and melt flowability, and reinforcing rigidity and heat resistance by excess talc filling, while increasing the weight of the molded article by increasing the density. There is an increasing problem.

Recently, polyolefin compositions prepared by extrusion of talc in ethylene-propylene block copolymers having a propylene homopolymer portion and a large amount of ethylene-propylene copolymer portions have been proposed, which are used in the propylene polymerization process. After polymerizing the copolymer, an ethylene-propylene block copolymer prepared by extrusion processing is mixed with talc, which is an inorganic filler, and then subjected to secondary extrusion. However, when the resin composition is manufactured by the off-line method as described above, the production cost is greatly increased compared to the in-line method, which is limited in terms of economical efficiency and use expansion.

The present invention is to solve the above problems of the prior art, in preparing a polypropylene-based resin composition, talc and ethylene-propylene block air in an extruder connected to a polypropylene production line producing the ethylene-propylene block copolymer The resin composition is continuously extruded by incorporating a talc master batch composed of coalescers in-line, and in particular, by using a high-stereoregular ethylene-propylene block copolymer, it is excellent in both rigidity, impact resistance and heat resistance, and excellent moldability. It is an object to provide a system resin composition.

That is, in one aspect of the present invention, after processing a mixture of an inorganic filler talc and ethylene-propylene block copolymer in a twin screw extruder or kneader to master batch, the talc master batch is ethylene-propylene block copolymer It provides a method for producing a polypropylene-based resin composition comprising the step of direct extrusion process by injecting directly into the extruder connected to the polypropylene production line in production.

According to another aspect of the present invention, a melt index (ASTM D1238: 230 ° C., 2.16 kg) containing 70 to 90 wt% of ethylene-propylene block copolymer and 10 to 30 wt% of talc prepared by the above method is 15 to 60 g. It provides a polypropylene resin composition that is / 10 minutes.

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

The ethylene-propylene block copolymer used in the present invention is a polypropylene resin having a melt index (ASTM D1238: 230 ° C., 2.16 kg) of 15 to 60 g / 10 minutes, and includes a propylene homopolymer part and an ethylene-propylene random copolymer part. And the ratio of two parts (alone: random) is 80:20 to 70:30 (w / w).

If the melt index of the ethylene-propylene block copolymer is less than 15 g / 10 minutes, appearance defects such as flow marks and tiger marks may occur when injection of a large product such as an automobile dash board or a complicated shape product such as an automobile grill. Exceeds 60 g / 10 min, the moldability is excellent while the impact property is drastically lowered.

In addition, when the propylene homopolymer portion of the ethylene-propylene block copolymer exceeds 80% by weight, the impact resistance is not good. On the other hand, when the propylene homopolymer portion is less than 70% by weight, the impact resistance is improved, but the rigidity and heat resistance are decreased and injection is not possible. Molded product productivity falls.

The ethylene-propylene block copolymer used in the present invention is a kind of high-stereoregular polypropylene, and the portion of the propylene homopolymer constituting a part thereof is 94% or more of stereoregularity (pentad isotactic fraction (measured by NMR method). %)). If the stereoregularity of the propylene homopolymer portion is less than 94%, the heat resistance and rigidity of the final resin composition are lowered.

On the other hand, the other component of the ethylene-propylene block copolymer, ethylene-propylene random copolymer is produced by copolymerizing ethylene and propylene in the propylene homopolymer portion, the ethylene content of 30 to 70% by weight. If the ethylene content of the ethylene-propylene random copolymer is less than 30% by weight, the crystalline propylene portion is increased, so that the impact resistance is insufficient, and if it exceeds 70% by weight, the crystalline ethylene portion is increased and the impact resistance is lowered.

On the other hand, in the present invention, talc, an inorganic filler used for improving mold release properties, high temperature dimensional stability, and rigidity, has a chemical composition of [3MgO 4SiO ₂ H ₂ O], and has an aspect ratio of 2 to 50. It is preferable to have a particle shape and an average particle size is 1-20 micrometers. If the aspect ratio of the talc is less than 2, there is a problem of lowering the rigidity, if it exceeds 50 there is a problem of poor appearance and impact resistance of the molded article. In addition, if the average particle size is less than 1㎛ particle agglomeration occurs during processing, the dispersibility and productivity is lowered, if it exceeds 20㎛ there is a problem of poor appearance and impact resistance of the molded article.

According to the method of the present invention, the talc is pre-mastered by mixing with the ethylene-propylene block copolymer and processing using a twin screw extruder or kneader prior to addition to the base resin. The talc master batches prepared in the present invention contain 40 to 70% by weight of talc and the remainder are ethylene-propylene block copolymers.

In general, in the case of resin production by the in-line compound method, the size of the extruder is usually large, so that dispersibility of talc often occurs, but as in the present invention, the master batch of talc and ethylene-propylene block copolymer When used, the dispersibility with the base resin is improved to show the same level of dispersibility as in the case of production by the existing offline compound method.

According to the method of the present invention, such a talc master batch is directly injected in-line into an extruder connected to a polypropylene production line producing an ethylene-propylene block copolymer to continuously extrude the resin, thereby improving rigidity, impact resistance and heat resistance. A polypropylene resin composition can be manufactured easily. Here, the ethylene-propylene block copolymer being produced in the polypropylene production line is a copolymer having the same properties as used in the talc master batch.

The polypropylene resin composition prepared according to the method of the present invention should contain 70 to 90% by weight of ethylene-propylene block copolymer and 10 to 30% by weight of talc, and a melt index of 15 to 60 g / 10 minutes (ASTM D1238: 230 ° C., 2.16 kg). When the content of the ethylene-propylene block copolymer in the resin composition is insufficient, the impact strength is lowered, when the content is increased, the impact strength is improved, but the rigidity and heat resistance are lowered.

In addition, the polypropylene resin composition of the present invention, if necessary, reinforcing agents, fillers, various additives such as dispersants, heat stabilizers, weather stabilizers, antistatic agents, lubricants, slip agents, nucleating agents, flame retardants, wollastonite, calcium carbonate, mica , Kaolin, clay, barium sulfate, calcium sulfate and the like can be added within a range not contrary to the object of the present invention. In particular, the dispersant is used for the purpose of dispersing the talc and the pigment contained in the resin of the present invention or neutralizing the catalyst residue, calcium stearate, zinc stearate, magnesium stearate , Hydrotalcite, polyoxyethylene stearyl ester, fatty acid amide, or mixtures thereof can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Examples and Comparative Examples

The ethylene-propylene block copolymer was mixed with talc in the mixing ratio of Table 1 below, followed by processing with kneader to prepare talc master batches used in Examples and Comparative Examples. Then, the ratio of the propylene homopolymer portion and the ethylene-propylene random copolymer portion in the block copolymer is 30 g / 10 min. Of ethylene-propylene block copolymer having a melt index (ASTM D1238: 230 ° C., 2.16 kg) as shown in Table 2 below. After the polymerization, the talc master batch prepared above was introduced into an in-line extrusion machine in the ethylene-propylene block copolymer polymerization process to prepare a polypropylene resin pellet having a composition shown in Table 2 below.

The resin pellets thus obtained were dried in an oven at 80 ° C. for 2 hours in consideration of the deterioration of physical properties due to moisture absorption, and then specimens for evaluation of physical properties were prepared using Samsung Klimkner FCM-110 injection machine (mold force = 110 tons). . At this time, the temperature distribution of the injection machine was set to 30/200/200/200/200 ℃ in the order of the nozzle in the feeding hopper, the mold temperature was set to 60 ℃, and the injection pressure is set to 60 ~ 100bar. The physical property evaluation results of each specimen thus prepared are shown in Table 2 below.

Composition of talc master batch Ingredient content Ethylene-propylene block copolymer (A) Propylene homopolymer ^a) Propylene Homopolymer Ratio (Weight Ratio) 70 Ethylene-propylene random copolymer ^b) Random copolymer ratio (weight ratio) 30 Ethylene Content (wt%) 40 Component a + component b 30 weight% Talc (C), average particle size 4㎛ 70 weight%

Composition and Physical Properties of Polypropylene Resin Composition Item Example Comparative example One 2 One 2 3 4 Ethylene-propylene block copolymer (A) Propylene homopolymer ^a) Propylene Homopolymer Ratio (Weight Ratio) 70 80 85 90 88 70 Stereogram (isotactic pentad fraction,%) 96 96 88 96 89 96 Ethylene-propylene random copolymer ^b) Random copolymer ratio (weight ratio) 30 20 15 10 12 30 Ethylene Content (wt%) 40 35 40 40 75 40 Component a + component b 70 85 70 70 85 100 Talc master batch (B) 30 15 30 - - - Talc (C), average particle size 4㎛ - - - 20 10 - Ethylene-propylene copolymer rubber (D) - - - 10 5 - Evaluation item MI (g / 10 min) 27 28 27 15 22 40 Density (g / cm 3) 1.04 0.98 1.04 1.04 0.98 0.91 Flexural Modulus (MPa) 2500 2350 2200 2150 1650 1200 Room temperature impact strength (23 ℃, kgfcm / cm) 28 22 5 15 8 40 Heat deflection temperature (℃) 125 132 124 123 120 110 Productivity (including manufacturing costs) Great Great Great Bad Bad Great Exterior Good Good Good Bad Bad Good

[Remarks]

1) Comparative Example 2: A resin composition was prepared by mixing component C and component D with component A by a conventional off-line method, followed by secondary extrusion.

2) Comparative Example 3: After the polymerization of component A by the in-line method, a mixture of C and D was directly introduced into an extruder connected to the polymerization production line of component A to prepare a resin composition continuously.

[Property evaluation method]

* Melt Index: ASTM D1238 (230 ℃, 2.16kg)

* Density: ASTM D1505

* Flexural Modulus: ASTM D790

* Impact strength at room temperature: ASTM D256

* Heat Deflection Temperature: ASTM D648

[result]

Example 1 and Comparative Example 1

Example 1 and Comparative Example 1 A resin composition prepared by injecting a talc master batch (component B) in-line, wherein the productivity and appearance are at the same level, but the proportion of the ethylene-propylene random copolymer portion in the ethylene-propylene block copolymer. In the case of the comparative example 1 which is less than 20 weight%, impact resistance fell remarkably.

Example 1 and Comparative Example 2

Example 1 and Comparative Example 2 is a composition having the same density, which is closely related to the weight of the final molded part, the impact properties and flexural rigidity is good, but in order to improve the impact resistance in the case of Comparative Example 2 by the conventional offline method Due to the addition of expensive ethylene-propylene copolymer rubber, the production cost is increased, the fluidity is inferior, and the problem of appearance defects due to the flow mark, etc. is caused, and inferior in terms of rigidity and heat resistance.

Example 2 and Comparative Example 3

Example 2 and Comparative Example 3 were also produced by the in-line process as a composition having the same density, but when talc and ethylene-propylene copolymer rubber is directly added without using a talc master batch as in Comparative Example 3, talc is quantitatively added. This was impossible, and the bulk density of the talc powder was low, so that the packing density of the feeding screw of the extruder was low, thereby reducing the extrusion productivity in the continuous production process. In addition, for Comparative Example 3 in which the proportion of the ethylene-propylene random copolymer portion in the ethylene-propylene block copolymer (component A) was less than 20% by weight and the ethylene content in the random copolymer was greater than 70% by weight, compared to Example 2. The fluidity level was similar but the impact resistance was insufficient. In addition, in the case of Comparative Example 3, the stereoregularity of the polypropylene homopolymer portion in the ethylene-propylene block copolymer (component A) is low, which is inferior in terms of rigidity and heat resistance compared to the examples.

Example 1 and Comparative Example 4

Example 1 and Comparative Example 4 Comparative Example 4 in which the composition of the ethylene-propylene block copolymer (component A) is the same and thus the fluidity, appearance, productivity, etc. are similar, but do not include talc or ethylene-propylene copolymer rubber at all. Due to the lack of rigidity and heat resistance and poor dimensional stability of injection molded articles, the development of applications to various kinds of injection molded articles is limited without additional rigidity or heat resistance reinforcement.

As described in detail above, the resin manufacturing method according to the present invention simplifies the multi-step process that has been pointed out as a disadvantage of the conventional method to improve the stiffness, impact resistance and heat resistance of the polypropylene resin composition in an inline manner in a one-step polymerization process It has the advantage that can be obtained directly, it is excellent in cost reduction effect compared to the conventional method. The polypropylene resin composition prepared by the method of the present invention is excellent in melt flow properties and excellent balance of physical properties such as rigidity, impact resistance and heat resistance This makes it suitable for producing complex large injection molded parts, especially for dashboard, trim and pillar parts, which are materials for automotive interior parts.

Claims (7)

Talc and ethylene-propylene block copolymers are processed into masterbatch by twin screw extruder or kneader, and then the talc masterbatch is inline with an extruder connected to the polypropylene production line producing ethylene-propylene block copolymer. Method of producing a polypropylene-based resin composition comprising the step of direct extrusion by continuous injection. 2. The process of claim 1, wherein the talc master batch comprises 40 to 70 weight percent talc, the remainder being ethylene-propylene block copolymers. The method of claim 2, wherein the talc has a chemical composition of [3MgO 4SiO ₂ H ₂ O], has an aspect ratio of 2 to 50 plate-shaped particles, and has an average particle size of 1 to 20 µm. How to. The melt index (ASTM D1238: 230 ° C., 2.16 kg) of the ethylene propylene block copolymer is 15 to 60 g / 10 minutes, and comprises a propylene homopolymer portion and an ethylene-propylene random copolymer portion. Composition ratio (alone: random) is 80:20 to 70:30 (w / w). 5. The method of claim 4 wherein the isotactic pentad fraction of the propylene homopolymer portion is at least 94%. 5. The method of claim 4 wherein the ethylene content of the ethylene-propylene random copolymer portion is 30-70 wt%. A melt index (ASTM D1238: 230 ° C., 2.16 kg), comprising 70-90% by weight of ethylene-propylene block copolymer and 10-30% by weight of talc, prepared according to the method of claim 1, wherein the melt index is 15-60 g / 10 min. Polypropylene resin composition.