KR20140038730A - Polypropylene resin composition and process for their manufacture - Google Patents

Abstract

The present invention provides a polypropylene resin composition comprising a polypropylene resin (c) composed of (a) 75-95 wt% of one random co-polymer selected from ethylene-propylene random copolymers containing 0.5-7 wt% of ethylene or butene-propylene random copolymers containing 1-15 wt% of butane and (b) 5 to 25 wt% of ethylene-propylene block copolymers containing 20-25 wt% of ethylene, and intrinsic viscosity ratio of (b) ethylene-propylene block copolymers to (a) one random co-polymer selected from the ethylene-propylene random copolymers or the butene-propylene random copolymers is 0.3-1.0.

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition and a process for producing the same,

The present invention relates to a polypropylene resin composition and a process for producing the same.

The polypropylene resin is superior in rigidity, chemical resistance and moldability to other polyolefin materials, and is widely used for automobile interior and exterior parts, home appliance parts, and the like. However, the homopolypropylene resin is transparent in the case of a thin film, but is not transparent in a thick product having a thickness of 2 mm or more and is not suitable as a transparent container material in which the inside is visible. Therefore, -Propylene random copolymer is widely used as a transparent container material.

However, since the ethylene-propylene random copolymer is somewhat weak in impact resistance, it can not be applied to a bulky and heavy product, and is particularly difficult to apply to applications requiring impact resistance such as refrigeration or freezing containers necessary for storing foods .

In order to compensate for the weakness of transparency and impact strength of the polypropylene resin, a metallocene ethylenic rubber may be blended with a polypropylene resin. However, this method is limited to the dispersion of polypropylene and metallocene ethylenic rubbers The transparency of the product is drastically lowered, so that it can not be used for the purpose of transparent products. Further, since the whitening occurs to various impacts that may occur during the manufacturing process of the product or during use of the product, There is a disadvantage that it falls.

In recent years, polypropylene has been used as a transparent injection material in which engineering polymers such as polyethylene terephthalate (PET) and transparent ABS have been mainly used, but transparency and impact resistance have been demanded.

An object of the present invention is to provide a polypropylene resin composition excellent in impact resistance, transparency and whitening resistance in order to solve the above problems.

The present invention relates to a random copolymer (a) selected from an ethylene-propylene random copolymer having an ethylene content of 0.5 to 7% by weight or a butene-propylene random copolymer having a butene content of 1 to 15% by weight, And a polypropylene resin (c) comprising 5 to 25% by weight of an ethylene-propylene block copolymer (b) having an ethylene content of 20 to 50% by weight,

Wherein the ethylene-propylene block copolymer (b) has an intrinsic viscosity ratio of from 0.3 to 1.0 with respect to one random copolymer (a) selected from the ethylene-propylene random copolymer or the butene-propylene random copolymer. Lt; / RTI >

The present invention also relates to a process for producing a propylene random copolymer or a butene propylene random copolymer by polymerizing ethylene or butene and propylene to produce an ethylene propylene random copolymer or a butene propylene random copolymer; And a second polymerization step of polymerizing the ethylene propylene block copolymer in the presence of the produced ethylene propylene random copolymer or butene propylene random copolymer.

The polypropylene resin composition of the present invention is excellent in impact resistance, transparency, and whitening resistance and can be used as a refrigerating container, a freezing container, a multipurpose storage box, a food packaging container, a bottle cap, a packaging film, a protective film, a decor sheet, a retort pouch, And the like.

The resin composition of the present invention comprises a polypropylene random block copolymer in which alpha-olefin propylene random copolymer and ethylene propylene block copolymer are polymerized stepwise in the reactor, more specifically, the polypropylene random block copolymer has an ethylene content (A) selected from ethylene-propylene random copolymer having an ethylene content of 0.5 to 7% by weight or butene-propylene random copolymer having a butene content of 1 to 15% by weight, and ethylene- (C) comprising 5 to 25% by weight of an ethylene-propylene block copolymer (b) having an ethylene-propylene random copolymer and a propylene random copolymer Wherein the ethylene-propylene block copolymer (b) has an intrinsic viscosity ratio of 0.3 to 1.0 with respect to the co-polymer (a) .

The alpha olefin propylene random copolymer is one random copolymer selected from an ethylene-propylene random copolymer or a butene-propylene random copolymer. When the alpha olefin has five or more carbon bonds, the reactivity of the comonomer is low, and copolymerization in the polymerization reactor is not easy.

The ethylene-propylene random copolymer or butene-propylene random copolymer (a) used in the present invention is a random copolymer prepared by simultaneously injecting ethylene or butene and propylene in a polymerization reactor, and the content of the ethylene component in the copolymer is 0.5 To 7% by weight, and the content of the butene component is preferably 1 to 15% by weight.

In the present invention, the role of the ethylene-propylene random copolymer or butene-propylene random copolymer component is to maintain the mechanical rigidity of the product, to impart an appropriate degree of heat resistance, and to have appropriate optical and thermodynamic compatibility with the component (b) It is to maintain transparency. If the content of the ethylene component in the random copolymer is 0.5% or the content of the butene component is less than 1% by weight, the degree of crystallization of the copolymer becomes unnecessarily high and the transparency of the resulting composition is lowered. If the content of the ethylene component in the random copolymer If the content of the 7 wt% or butene component exceeds 15 wt%, the degree of crystallization sharply decreases, the rigidity is lowered and the heat resistance is lowered, making it unsuitable as a material for containers used in daily life.

The ethylene-propylene random copolymer or butene-propylene random copolymer (a) contains 75 to 95% by weight based on the polypropylene resin (c). When the content of the ethylene-propylene random copolymer or the butene-propylene random copolymer (a) is less than 75% by weight, the rigidity of the final polypropylene resin composition is lowered, The content of the ethylene-propylene block copolymer to be polymerized is low and it is difficult to exhibit the impact resistance characteristic.

The ethylene-propylene block copolymer (b) is produced by continuously polymerizing the random copolymer (a) in the subsequent series of reaction apparatuses. The role of the ethylene-propylene block copolymer in the present invention is as follows: . Further, it has optical and thermodynamic compatibility with the component (a) to an appropriate degree, and it is possible to finely disperse in a micrometer or less when the composition is prepared, thereby imparting both transparency and whitening characteristics at the same time.

The ethylene content of the ethylene-propylene block copolymer is preferably 20 to 50% by weight. If the ethylene content in the copolymer is less than 20% by weight, the amorphous portion improving the impact in the polymer block to be polymerized is reduced and the impact resistance property is decreased. When the ethylene content is more than 50% by weight, And the impact resistance can be reduced due to interfacial peeling at the time of impact resistance.

The ethylene-propylene block copolymer (b) contains 5 to 25% by weight based on the polypropylene resin (c). When the content of the ethylene-propylene block copolymer is less than 5% by weight, impact resistance is not exhibited. When the content of the ethylene-propylene block copolymer is more than 25% by weight, rigidity and transparency are deteriorated.

The intrinsic viscosity (dl / g) of the ethylene-propylene block copolymer (b) in the polypropylene resin (c) divided by the number of the random polypropylene (a) selected from ethylene- The intrinsic viscosity ratio, calculated as intrinsic viscosity (dl / g), may be between 0.3 and 1.0. If the intrinsic viscosity ratio is less than 0.3, the molecular weight of the polymerized ethylene-propylene block copolymer is relatively lower than that of the continuous random copolymer, so that it is difficult to absorb the impact. If the intrinsic viscosity ratio is more than 1.0, the dispersed phase size of the ethylene- The transparency may be lowered.

The polypropylene resin is obtained by introducing one comonomer selected from ethylene or butene and propylene into the polymerization reactor simultaneously to obtain an ethylene-propylene random copolymer portion having an ethylene content of 0.5 to 7 wt% or an ethylene-propylene random copolymer portion having a butene content of 1 to 15 wt% 75 to 95% by weight of the butene-propylene random copolymerization portion is formed first, and in the subsequent series of reactions, the ethylene-propylene block copolymer portion having an ethylene content of 20 to 50% by weight is added to the formed random copolymer portion in an amount of 5 to 25 wt% % ≪ / RTI > to form the polypropylene resin.

The polypropylene resin composition according to the present invention may further contain a nucleating agent containing a sorbitol or nonitol structure in its chemical molecular structure, and the content thereof is preferably 0.07% by weight to 0.5% by weight with respect to the polypropylene resin composition . If the content of the nucleating agent is less than 0.07% by weight, nucleophilic nucleating action of the nucleating agent is insufficient, and the number of generated crystals is small and the size is large and high transparency is not expressed. If the content is more than 0.5% by weight, Which is not preferable.

Specific examples of the nucleating agent include a sorbitol-based nucleating agent such as benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol, 3,4-dimethylbenzylidene sorbitol, and 1,2,3-trideoxy-4,6: -Bis-O - [(4-propylphenyl) methylene] nonitol, and the like.

The melt index (ASTM D 1238, 230 ° C / 2.16 kg, Melt Index, MI) of the polypropylene resin composition may be 1 to 50 g / 10 min. If the melt index is less than 1 g / 10 min, the resin flow characteristics in the extrusion process are lowered, and it is difficult to maintain the intrinsic viscosity ratio at the optimum condition of 0.3 to 1.0. When the melt index is more than 50 g / 10 min, The impact resistance characteristic of the final product may be deteriorated.

The polypropylene resin composition may further comprise an MI synergist.

The MI enhancer may be selected from at least one of organic peroxides such as bis (t-butylperoxyisopropyl) benzene. The content of the MI enhancer may be 0.003 to 0.03 wt% based on 100 wt% of the resin composition of the present invention. .

If the content of the MI enhancer is less than 0.003% by weight, the dispersibility of the polypropylene resin (c) may not be dispersed in the resin and the MI synergy may deteriorate. If the content of the polypropylene resin (c) (b) ÷ the intrinsic viscosity ratio of one random polypropylene (a) selected from ethylene-propylene random polypropylene or butene-propylene random polypropylene is increased and the transparency is decreased due to an increase in the dispersed phase size of the ethylene- And the content of volatile substances is increased, so that application to food containers is limited.

Additives such as an antioxidant, a catalyst neutralizing agent, a pigment, a dispersant, a lubricant, an antistatic agent, a UV stabilizer, a slip agent, an anti-blocking agent, and talc may be added to the resin composition of the present invention. The content of the added component can be appropriately adjusted by those skilled in the art within the scope of not hurting the object of the present invention.

The polypropylene resin composition may further comprise an antioxidant. Specific examples of the antioxidant include tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrosilylate) and 1,3,5-trimethyl-tris (3,5- (2,4-di-t-butylphenol) phosphite, and the like, and the like. However, it is not limited thereto. It is not limited. The antioxidant may be contained in an amount of 0.1 to 0.5% by weight based on the polypropylene resin composition. If the content of the antioxidant is less than 0.1% by weight, it is difficult to secure the stability of the resin composition due to oxidation. If the content of the antioxidant is more than 0.5% by weight, dissolution and economical efficiency of the antioxidant may be problematic.

The polypropylene resin composition may further include a catalyst neutralizing agent. The catalyst neutralizing agent neutralizes the catalyst when the catalyst used in the synthesis of the polymer remains as a residue. The catalyst neutralizing agent may be any catalyst neutralizing agent used in the art, and preferably calcium stearate or hydrotalcite. The catalyst neutralizing agent may be contained in an amount of 0.01 to 0.5% by weight based on the polypropylene resin composition.

The polypropylene resin composition may further include a colorant. The pigment serves to improve the appearance of the final product. The pigment may be any pigments used in this technical field, and may be included in an amount of 0.001 to 0.5% by weight based on the polypropylene resin composition.

The present invention provides a process for producing the polypropylene resin composition.

The method for producing the polypropylene resin composition includes a step of preparing an ethylene-propylene random copolymer or a butene-propylene random copolymer and a step of producing an ethylene-propylene block copolymer.

That is, a first polymerization step of polymerizing ethylene or butene and propylene to prepare an ethylene-propylene random copolymer or a butene-propylene random copolymer; And a second polymerization step of polymerizing the ethylene-propylene block copolymer in the presence of the produced ethylene-propylene random copolymer or butene-propylene random copolymer.

The ethylene-propylene random copolymer or the butene-propylene random copolymer according to the present invention is produced in a continuous polymerization process, and the catalyst can be used without limitation in the catalysts known in the art. Specifically, a titanium compound and a phthalate A catalyst prepared by reacting an internal electron donor in the system may be used, and a catalyst containing an organoaluminum compound and an external electron donor may further be used.

The continuous polymerization process may be carried out by a polypropylene polymerization process known in the art, and may preferably be gas phase polymerization or bulk polymerization.

After the ethylene-propylene random copolymer or butene-propylene random copolymer is prepared, the ethylene-propylene block copolymer is continuously polymerized in the presence of the random copolymer.

The step of preparing the ethylene-propylene block copolymer may be carried out by a polypropylene polymerization method known in the art, preferably by vapor phase polymerization or bulk polymerization.

The method for producing a polypropylene resin composition according to the present invention may further comprise a mixing step for kneading after the polymerization step.

The mixing step may be carried out according to a conventional method for producing a resin composition. For example, a resin composition can be prepared by charging the components into a stirring-mixing apparatus, stirring and mixing the mixture for 1 to 30 minutes, melting and kneading at a temperature of 180 to 230 DEG C using a rolling mill or an extruder have.

The resin composition of the present invention can be molded by any method such as extrusion, blow molding, film molding, injection molding, and vacuum molding, but is not limited thereto. The resin composition may be used for various purposes such as a multipurpose storage box, a product for storing refrigerated / But is not limited thereto.

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

Preparation of resin composition

Example  One

- Preparation of ethylene-propylene random copolymer (a)

Propylene random copolymer (a) was prepared by injecting propylene and ethylene simultaneously into the reaction apparatus to carry out a bulk polymerization reaction, and copolymerizing the resulting copolymer so that the ethylene content was 2% by weight.

- Preparation of ethylene-propylene block copolymer (b) and production of polypropylene resin

(A) in the presence of the ethylene-propylene random copolymer (a) in a series of reaction apparatuses after the polymerization of the ethylene-propylene random copolymer (a), wherein the ethylene content in the ethylene propylene block copolymer (B) is 12% by weight when the content of the component (a) is 88% by weight and the intrinsic viscosity ratio is 0.85 when the content of the component (a) is 88% The polymerization amount was adjusted to obtain a polypropylene resin kneaded with (a) and (b).

- Preparation of pellets

To the polypropylene resin obtained in the above step, 2000 ppm of NX8000 as a nucleating agent, 1000 ppm of Iganox 1010 as a phenolic antioxidant, 1000 ppm of Iganox 168 as a phosphate antioxidant, and 500 ppm of calcium stearate as a catalyst neutralizing agent were added, And the mixture was melted and mixed through an extruder to be pelletized to prepare a polypropylene resin composition.

Example  2

-Polypropylene resin was prepared in the same manner as in Example 1 except that the components shown in Table 1 were prepared, and pellets and test specimens were prepared and evaluated for physical properties. The results are shown in Table 1.

Example  3 to 5

- The polypropylene resin was prepared in the same manner as in Example 1 except that the melt index was 5 g / 10 min before adding the MI ascending agent,

1000 ppm of NX8000 as a nucleating agent, 1000 ppm of a phenolic antioxidant, 1000 ppm of Iganox 168 as a phosphate-based antioxidant, 500 ppm of calcium stearate as a catalyst neutralizing agent and MI ascorbate as a nucleating agent were added to the polypropylene resin obtained in the above step The resulting mixture was further melt-mixed at 220 DEG C through a twin-screw extruder and pelletized to prepare a polypropylene resin composition, and test specimens were prepared and evaluated for physical properties. The results are shown in Table 1.

Comparative Example  1 to 4

- Polypropylene resin was prepared in the same manner as in Example 1 except that the components shown in Table 2 were prepared, and pellets and test specimens were prepared and evaluated for their physical properties. The results are shown in Table 2.

Example  6 to 8

The polypropylene resin was prepared in the same manner as in Example 1 except that the melt flow rate prior to the addition of the MI ascending agent was 4 g / 10 min.

By adding to a polypropylene resin obtained in the above step nucleating agent NX8000 2000ppm, phenolic Iganox 1010 as an antioxidant 1000 ppm, a phosphate-based antioxidant, Iganox 168 1000 ppm, 500 ppm calcium stearate as a catalyst neutralizer biaxially at 220 ^o C And the mixture was melted and mixed through an extruder to be pelletized to prepare a polypropylene resin composition, and test specimens were prepared and evaluated for physical properties. The results are shown in Table 3.

Method of analyzing resin composition

The polypropylene resin compositions of Examples and Comparative Examples were analyzed by the following methods.

Ethylene content: Ethylene content was measured using a 720, 740 cm-1 characteristic peak using an infrared absorption spectrum (FT-IR).

Butene Content: The content of butene was measured using an infrared absorption spectrum (FT-IR) using a characteristic peak of 771 cm < -1 >.

- Intrinsic viscosity ratio: The intrinsic viscosity was measured using a viscosity meter under a decalin solution at 135 ° C. The solvent extract of the ethylene-propylene block copolymer (b) shows the components solubilized at 150 ° C using a xylene solvent. The intrinsic viscosity ratio was calculated as follows.

Intrinsic viscosity ratio = ethylene-propylene block copolymer (b) / intrinsic viscosity of one random polypropylene (a) selected from ethylene-propylene random polypropylene or butene-propylene random polypropylene

Preparation of specimen and evaluation method

The polypropylene specimens of the examples and comparative examples, and the physical properties of the resins and the specimens were measured by the following methods.

- Production of sheet: Using the resin compositions obtained in the above Examples and Comparative Examples, a sheet having a width of 120 mm x 120 mm x 2 mm was produced. The degree of blur of the sheet, the surface impact strength and the whiteness degree were measured, and the results are shown in Table 2.

- Preparation of Specimen: An ASTM specimen was prepared using the resin compositions obtained in the above 1.

Melt Index: The melt index was measured under a load of 2.16 kg at 230 占 폚 according to ASTM D1238.

- Cloudiness: The degree of cloudiness of a 2 mm sheet was measured according to ASTM D1003.

- Notch Izod impact strength: measured according to ASTM D256.

- Surface Impact Strength: According to ASTM D5420, a falling weight impact (J) was measured at 23 ° C and 0 ° C using a Gardner type impactor using 2 mm thick injection sheet specimens.

- Bleaching test: The diameter (mm) of the whitening area was measured and recorded when a 5 kg weight (25 mm diameter) was dropped on a 2 mm sheet at a height of 20 cm and impacted.

Item unit Example Example Example Example Example -One -2 -3 -4 -5 The composition of component (a) Propylene content, wt% 98 96 98.5 96 95 Ethylene content, wt% 2 0 1.5 0 0 Butene content, wt% 0 4 0 4 5 The composition of component (b) Propylene content, wt% 72 59 60 62 61 Ethylene content, wt% 28 41 40 38 39 In polypropylene resin
The content of component (b) weight% 12 13 12 12 13 Intrinsic viscosity ratio 0.85 0.9 0.8 0.9 0.8 Content of nucleating agent weight% 0.2 0.2 0.2 0.2 0.2 Content of MI ascorbate weight% 0 0 0.005 0.01 0.025 Melt Index g / 10 min 12 13 9 13 21 Cloudiness % 28 30 32 32 34 Impact strength (23 ℃) kgcm / cm 27 28 25 27 14 Impact strength (0 ℃) kgcm / cm 8 7 7 7 5 Surface impact strength (23 ℃) J 22 23 22 22 21 Surface Impact Strength (0 ℃) J 21 22 22 22 20 Bleaching mm 1.3 1.4 1.4 1.4 1.5

Item unit Comparative Example Comparative Example Comparative Example Comparative Example -One -2 -3 -4 The composition of component (a) Propylene content, wt% 100 95 98 98.5 Ethylene content, wt% 0 0 2 1.5 Butene content, wt% 0 5 0 0 The composition of component (b) Propylene content, wt% 70 61 31 59 Ethylene content, wt% 30 39 69 41 In polypropylene resin
The content of component (b) weight% 12 12.5 13 12 Intrinsic viscosity ratio 0.95 2.3 0.85 0.1 Content of nucleating agent weight% 0.2 0.2 0.2 0.2 Content of MI ascorbate weight% 0 0 0 0 Melt Index g / 10 min 12 13 14 13 Cloudiness % 84 66 68 48 Impact strength (23 ℃) kgcm / cm 11 10 11 9 Impact strength (0 ℃) kgcm / cm 6 5 6 5 Surface impact strength (23 ℃) J 21 16 17 15 Surface Impact Strength (0 ℃) J 15 11 14 10 Bleaching mm 2.1 2.3 2.2 2.0

Item unit Example Example Example -6 -7 -8 The composition of component (a) Propylene content, wt% 98 96 98.5 Ethylene content, wt% 2 0 1.5 Butene content, wt% 0 4 0 The composition of component (b) Propylene content, wt% 72 59 60 Ethylene content, wt% 28 41 40 In polypropylene resin
The content of component (b) weight% 12 13 12 Intrinsic viscosity ratio 0.85 0.9 0.8 Content of nucleating agent weight% 0.2 0.01 0.7 Content of MI ascorbate weight% 0.001 0.01 0.01 Melt Index g / 10 min 4 12 12 Cloudiness % 34 63 25 Impact strength (23 ℃) kgcm / cm 28 12 11 Impact strength (0 ℃) kgcm / cm 6 6 6 Surface impact strength (23 ℃) J 21 21 18 Surface Impact Strength (0 ℃) J 20 20 17 Bleaching mm 1.6 2.0 1.4

As described in detail above, the present invention is to provide a refrigerator, a refrigerator container, a multi-purpose storage container, a food packaging container, a bottle cap, a packaging film, a protective film, a decor sheet, a retort pouch, A polypropylene resin composition suitable for an extrusion blow molding or the like can be provided.

Claims (9)

75 to 95% by weight of one random copolymer (a) selected from an ethylene propylene random copolymer having an ethylene content of 0.5 to 7% by weight or a butene propylene random copolymer having a butene content of 1 to 15% by weight, (C) comprising 5 to 25% by weight of an ethylene-propylene block copolymer (b) of 50 to 50% by weight,
Wherein the ethylene-propylene block copolymer (b) has an intrinsic viscosity ratio of from 0.3 to 1.0 with respect to one random copolymer (a) selected from the ethylene-propylene random copolymer or the butene-propylene random copolymer. Composition. The polypropylene resin composition according to claim 1, wherein the polypropylene resin composition has a melt index (230 占 폚 / 2.16 kg) of 1 to 50 g / 10 minutes. The polypropylene resin according to claim 1, wherein the polypropylene resin composition further contains at least one nucleating agent selected from the group consisting of sorbitol-based and non-nitol-based nucleating agents in an amount of 0.07 to 0.5 wt% based on the polypropylene resin composition. Composition. The polypropylene resin composition according to claim 1, wherein the polypropylene resin composition further contains an MI synergist at 0.003 to 0.03 wt% based on the polypropylene resin composition. The polyimide resin composition according to claim 1, further comprising at least one member selected from the group consisting of an antioxidant, a catalyst neutralizing agent, a pigment, a dispersant, an endurance agent, an antistatic agent, a UV stabilizer, a slip agent, Propylene resin composition. A first polymerization step of polymerizing ethylene or butene and propylene to produce an ethylene propylene random copolymer or a butene propylene random copolymer; And a second polymerization step of polymerizing the ethylene propylene block copolymer in the presence of the prepared ethylene propylene random copolymer or butene propylene random copolymer. The method for producing a polypropylene resin composition according to claim 6, wherein the polymerization is carried out by gas phase polymerization or bulk polymerization. The method of claim 6, further comprising a mixing step after the polymerization step. A refrigerator container, a refrigerator container, a multi-purpose storage container, a food packaging container, a bottle cap, a packaging film, a protective film, a deco sheet, a retort pouch, a medicine container or an extruded hollow article containing the polypropylene resin composition of claim 1.