KR20120113420A - A polypropylene resin composition, manufacturing method thereof and sheet manufactured by thereof - Google Patents

Abstract

PURPOSE: A polypropylene-based resin composition, a manufacturing method thereof, and a sheet manufactured by the same are provided to provide products. CONSTITUTION: A polypropylene-based resin composition comprises a first ethylene propylene random copolymer having 0.5-3.0 wt% of ethylene content and a second ethylene propylene random copolymer having ethylene content of 4.0-15 wt%. The first and second ethylene propylene random copolymers are mixed at the weight ratio of 3:7-7:3. The melt index of the polypropylene based resin composition is 1-15 g/10 min (230 deg. Celsius, 2.16 kg).

Description

A polypropylene resin composition, a method for producing the same, and a sheet produced therefrom {A polypropylene resin composition, manufacturing method

The present invention relates to a polypropylene resin composition, a method for producing the same, and a sheet prepared therefrom. Specifically, the present invention provides a product having not only excellent transparency, impact resistance, particularly low temperature impact resistance, but also excellent moldability and uniform physical properties. The present invention relates to a polypropylene resin composition, a method for producing the same, and a sheet produced therefrom.

In general, polypropylene resins are widely used in various resin products because they have a significantly higher softening temperature, excellent tensile strength, bending strength and stiffness, and low transparency, surface gloss and molding shrinkage of molded products, compared to high density polyethylene resins. .

However, polypropylene-based resins have a disadvantage in that impact strength is much lower than that of polyethylene-based resins, and in order to further increase the transparency of the molded article, when a nucleating agent is added to the polypropylene-based resin or when a copolymerization technique is used, the impact resistance characteristics thereof are caused. There is a problem that is worse. In particular, polypropylene-based resins are easily broken during use / transportation in winter due to their low temperature impact resistance.

In order to compensate for the weakness of such impact strength, polypropylene-based resins may be used by blending metallocene ethylene-based rubber, but the rubber is expensive and the economical efficiency is lowered. As it appears, the use is limited.

Recently, random polypropylene copolymers have been used for packaging materials for household goods in which engineering polymers such as polycarbonate (PC) and polyethylene terephthalate (PET) have been used. However, physical properties such as transparency, impact resistance, and workability are required for the packaging material, but polypropylene-based resins have many problems in winter because of their poor impact resistance.

An object of the present invention to solve the above problems is not only excellent transparency, impact resistance, especially low temperature impact resistance, but also excellent in formability and uniform physical properties of a polypropylene resin composition, a method for preparing the same and this It is to provide a manufactured sheet.

The present invention to achieve the above object,

First ethylene-propylene random copolymer having an ethylene content of 0.5 to 3.0 wt%; And a second ethylene-propylene random copolymer having an ethylene content of 4.0 to 15% by weight,

Provided is a polypropylene resin composition having different ethylene content between the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer.

The first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer may be mixed in a weight ratio of 3: 7 to 7: 3.

The melt index of the polypropylene resin composition may be 1 to 15 g / 10 min (230 ° C., 2.16 kg).

The molecular weight distribution index (PI) of the polypropylene resin composition may be 4 to 10.

The polypropylene resin composition may further include an antioxidant in an amount of 0.1 to 0.5 parts by weight based on the first and second ethylene-propylene random copolymers.

The polypropylene resin composition may further include a nucleating agent in an amount of 0.01 to 0.5 parts by weight based on the first and second ethylene-propylene random copolymers.

The polypropylene resin composition may further include a catalyst neutralizing agent in an amount of 0.05 to 2 parts by weight based on the first and second ethylene-propylene random copolymers.

In order to achieve the other object of the present invention,

Gas phase polymerization of ethylene and propylene in the presence of a catalyst to produce a first ethylene-propylene random copolymer; And

It provides a method for producing a polypropylene resin composition comprising a second polymerization step of additionally adding ethylene and propylene in the presence of the first ethylene-propylene random copolymer to produce a second ethylene-propylene random copolymer by gas phase polymerization. do.

After the second polymerization step, a mixing step of melting and kneading the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer may be further included.

The first polymerization step and the second polymerization step may be performed in a plurality of reactors or a single reactor having two independent zones.

In order to achieve another object of the present invention,

It provides a sheet produced by calendering the polypropylene resin composition of the present invention.

The polypropylene resin composition of the present invention is excellent in transparency and impact resistance without using expensive ethylene-based rubber to produce a transparent product, it is convenient to transport and use in winter.

Polypropylene-based resin composition of the present invention is excellent in compatibility and does not occur phase separation even if a separate mixing process, it can provide a product with uniform physical properties.

Polypropylene-based resin composition of the present invention is excellent in moldability and easy sheet molding through calendering.

According to the method for producing a polypropylene resin composition of the present invention, since a ethylene-propylene random copolymer having a different ethylene content can be produced in a series of continuous processes, the production process is simple and the production time is also shortened.

Hereinafter, the present invention will be described in detail so that those skilled in the art can easily practice.

The polypropylene resin composition of the present invention contains two or more kinds of ethylene-propylene random copolymers having different ethylene contents. By including two or more kinds of random copolymers having different ethylene contents, the impact resistance of the polypropylene resin is improved while the rigidity is not lowered.

The polypropylene resin composition includes at least one first ethylene-propylene random copolymer having an ethylene content of 0.5 to 3.0 wt% based on the random copolymer. The first ethylene-propylene random copolymer is a random copolymer having a relatively low content of ethylene and serves to prevent stiffness of the final product made of the polypropylene resin. When the ethylene content is less than 0.5% by weight, impact resistance may be lowered. When the ethylene content is higher than 3.0% by weight, the rigidity of the molded product may be lowered.

The polypropylene resin composition includes at least one second ethylene-propylene random copolymer having an ethylene content of 4 to 15% by weight based on the random copolymer. The second ethylene-propylene random copolymer is a random copolymer having a relatively high ethylene content and serves to improve the impact resistance of the polypropylene resin. When the ethylene content is less than 4% by weight, the impact resistance may be lowered. When the ethylene content is more than 15% by weight, the rigidity of the final molded product may be lowered.

The first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer may be mixed in a single phase. The first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer have excellent compatibility so that no phase separation occurs even without a separate mixing process. The first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer may be prepared independently by a separate polymerization process and then mixed by melt mixing or blending, but may be mixed by a continuous series of polymerization processes. The ethylene-propylene random copolymer and the second ethylene-propylene random copolymer can be polymerized simultaneously. That is, after the polymerization of the first ethylene-propylene random copolymer, the polymerization of the second ethylene-propylene random copolymer proceeds continuously in the presence thereof, and if the process is repeated several times, the first and second ethylene-propylene random copolymers Are alternately polymerized and mixed in the polymerization process so that they exist as a single phase without a separate blending process. In this case, the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer are polymerized in a weight ratio of 3: 7 to 7: 3, preferably in a weight ratio of 4: 6 to 6: 4, May exist in a single phase. When polymerized and present at a polymerization ratio within the above range, the impact resistance is improved while the rigidity is not lowered and the moldability is also excellent.

The melt index (Melt Index, MI) of the polypropylene resin composition may be 1 to 15 g / 10 min (230 ° C., 2.16 kg).

The melt index is a factor that affects the formability. When the melt index is less than 1 g / 10 min, the flowability of the resin may be reduced during sheet molding, which may cause difficulty in forming a large size sheet, and exceeds 15 g / 10 min. In this case, the melt strength may be lowered, the thickness of the sheet may become uneven when the sheet is formed, and the impact resistance may be lowered.

The molecular weight distribution index (PI) of the polypropylene resin composition may be 4 to 10. The said molecular weight distribution index shows the distribution degree of the molecular weight of resin, and is calculated by ratio (Mw / Mn) of a weight average molecular weight (Mw) and a number average molecular weight (Mn). When the molecular weight distribution index is less than 4, it is not preferable to secure the sag stability and improve the flowability during sheet processing, and when it exceeds 10, the stiffness may be increased but transparency may be reduced.

The polypropylene resin composition may further include a single or a mixture thereof selected from the group consisting of an antioxidant, a nucleating agent, and a catalyst neutralizing agent.

The antioxidant is to ensure the heat resistance of the final molded article, preferably from 0.1 to 0.5 parts by weight relative to the first and second ethylene-propylene random copolymer. When included in less than 0.1 part by weight it may be difficult to ensure the heat resistance stability, if the amount exceeds 0.5 parts by weight compared to the addition amount is not efficient because the effect of improving the thermal stability is insignificant. The antioxidants specifically include tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrosilylate) and 1,3,5-trimethyl-tris (3,5-di-t- Phenolic antioxidants such as butyl-4-hydroxybenzene) and the like or mixtures thereof selected from the group consisting of phosphite antioxidants such as tris (2,4-di-t-butylphenol) phosphite However, the present invention is not limited thereto.

The nucleating agent is used for the purpose of improving transparency and heat resistance of the injection molded article, and may be preferably included in an amount of 0.01 to 0.5 parts by weight based on the first and second ethylene-propylene random copolymers. When the content of the nucleating agent is less than 0.01 parts by weight, it is difficult to secure transparency, and when the content of the nucleating agent is more than 0.5 parts by weight, the transparency improving effect is insignificant compared to the amount added, which is not efficient. Specifically, the nucleating agent may specifically include a sorbitol-based nucleating agent such as benzylidene sorbitol, methylbenzylidene sorbitol, ethylbenzylidene sorbitol and 3,4-dimethylbenzylidene sorbitol, and an aluminum-based nucleating agent such as aluminum hydroxy-di-t-butylbenzoate. Sodium nucleating agents such as sodium 2,2-methylenebis (4,6-di-t-butylphenyl) phosphate and the like and magnesium oxide silicate (talc: MgO? SiO ₂ ) may be used alone or in a mixture thereof. It may be, but is not limited thereto.

The catalyst neutralizing agent is used to neutralize the catalyst used in the polymerization reaction, and may be preferably included in an amount of 0.05 to 2.0 parts by weight based on the first and second ethylene-propylene random copolymers. If the catalyst neutralizing agent is included in less than 0.05 parts by weight, it may be difficult to neutralize when the catalyst used in the polymerization reaction remains in the polymer to remain as a catalyst residue, and if it exceeds 2.0 parts by weight exceeds the content necessary for neutralizing the catalyst Not only are they inefficient, they can cause side reactions or affect the physical properties of the polymer. The catalyst neutralizing agent may be used without limitation to those known in the art, specifically, calcium stearate or synthetic hydrotalcite may be used, but is not limited thereto.

The polypropylene resin composition of the present invention may optionally further include components known in the art, in addition to the above components, as long as the object of the present invention is not impaired. Specifically, additives, such as a UV stabilizer, a pigment, a flame retardant, an antistatic agent, can be used together.

The present invention also comprises a first polymerization step; And it provides a method for producing a polypropylene resin composition comprising a second polymerization step. In addition, the manufacturing method of the polypropylene resin composition may further include a mixing step.

Method for producing a polypropylene resin composition of the present invention comprises a first polymerization step; And the second polymerization step may be performed in a series of continuous processes to continuously prepare ethylene-propylene random copolymers having different ethylene contents, and copolymers having different ethylene contents may be mixed with each other while being polymerized alternately. Therefore, a copolymer having different ethylene contents is not produced by a separate polymerization process, so the manufacturing process is easy and simple.

The first polymerization step is a step of producing a first ethylene-propylene random copolymer by gas phase polymerization of ethylene and propylene in the presence of a catalyst.

Ethylene-propylene random copolymers may be prepared by gas phase polymerization by the first polymerization step, and ethylene and propylene, which are polymerization raw materials, may be arbitrarily adjusted by those skilled in the art, preferably, an ethylene content of 0.5 to 3 wt% The dosage of ethylene and propylene can be adjusted to

The catalyst may be any catalyst known in the art without limitation, and specifically, a catalyst prepared by reacting a titanium compound and a succinate-based internal electron donor with a dialkoxy magnesium carrier may be used. Further catalysts including electron donors can be used.

The gas phase polymerization may be carried out by conventional methods known in the art.

The second polymerization step is a step of preparing a second ethylene-propylene random copolymer by gas phase polymerization by additionally adding ethylene and propylene in the presence of the first ethylene-propylene random copolymer.

In the second polymerization step, since the second ethylene-propylene random copolymer having a different ethylene content is polymerized in the presence of the first ethylene-propylene random copolymer, the second ethylene-propylene random copolymer is disposed on the first ethylene-propylene random copolymer. Can be obtained.

In addition, the content of ethylene and propylene to be added may be arbitrarily adjusted by those skilled in the art. Preferably, ethylene and propylene may be added so that the content of ethylene is 4 to 15% by weight.

The first polymerization step and the second polymerization step may be repeated several times alternately as required by those skilled in the art. When the first polymerization step and the second polymerization step are repeated several times, a composition in which copolymers having different ethylene contents are alternately laminated in several layers may be obtained.

The first polymerization step and the second polymerization step may be performed in a plurality of reactors or a single reactor having two independent zones.

When the polymerization is carried out in a plurality of reactors, the first polymerization step is carried out in a first reactor to prepare a first ethylene-propylene random copolymer, which is then transferred to a second reactor, and ethylene and propylene are further added thereto. Second ethylene-propylene random copolymers of different contents can be polymerized continuously. In addition, this process can be carried out continuously and repeatedly while transferring the polymerized random polymer to the third and fourth reactors as required by those skilled in the art.

When carried out in a single reactor having two independent zones, the first ethylene-propylene random copolymer is prepared by the conventional method in the first zone, and then additionally added ethylene and propylene while rotating it to the second zone in the same reactor. Thus, the second ethylene-propylene random copolymer having different ethylene contents may be polymerized, and the second ethylene-propylene random copolymer is laminated on the first ethylene-propylene random copolymer. In addition, by repeating the above process, the ethylene and propylene were added while rotating the product prepared up to the second ethylene-propylene random copolymer back to the first region, and additionally the first ethylene-propylene on the second ethylene-propylene random copolymer. Random copolymers can be polymerized. When this series of steps is repeated, a polymer in which a first ethylene-propylene random copolymer and a second ethylene-propylene random copolymer are alternately stacked may be formed .

The mixing step is a step of melt kneading the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer after the second polymerization step.

In the mixing step, the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer are melt mixed to exist as a single phase, and because of excellent compatibility, no phase separation occurs, and thus no separate blending process is required.

The melt kneading may be performed by a conventional method known in the art, but specifically, the random copolymer obtained in the first polymerization step and the second polymerization step may be performed by extruding through an extruder. In addition, in the mixing step, in addition to the first and second ethylene-propylene random copolymer, it may be melt kneaded by mixing an antioxidant, a nucleating agent, a catalyst neutralizer and other additives. More specifically, an antioxidant, a nucleating agent, a catalyst neutralizer and an additive are added to the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer, followed by melt mixing at 180 to 230 ° C. with a twin screw extruder. . The melt-mixed mixture is discharged into a strand through a die of a twin screw extruder, and then cooled and cut with cooling water to prepare a polypropylene resin composition pellet. This process can be carried out in a continuous process.

The polypropylene resin composition of the present invention may be applied to various fields such as sheet, film or injection molding, and may be manufactured by any method known in the art. Specifically, cast or blow film, etc. can be produced, and the moldability is easy due to the excellent moldability.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. This is for the purpose of illustrating the present invention, and thus the scope of the present invention is not limited thereto.

< Manufacturing example  1 to 6> Polypropylene system  Preparation of resin composition

Ethylene and propylene were introduced into two independent regions in one polymerization reactor using a porous solid titanium catalyst prepared by reacting diethoxy magnesium with a titanium tetrachloride compound and an internal electron donor succinate compound in the presence of a hydrocarbon solvent. Thus, a random copolymer having different ethylene contents was gas-phase polymerized to prepare a polypropylene resin having a composition shown in Table 1 below.

division Ethylene content Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Manufacture example 6 Primary copolymer 2 2.5 0.5 3 One 5 Secondary copolymer 5 6.5 6.5 6.5 3.5 10 First Copolymer: Second Copolymer
(Weight ratio) 5: 5 5: 5 5: 5 7: 3 5: 5 5: 5

< Example  1 to 4 Pellets  And manufacture of sheets

The additive was mixed with the polypropylene resin prepared in Preparation Example in the composition shown in Table 2 and pelletized by melt mixing with a twin screw extruder, and the sheet was manufactured to a thickness of 1 mm using a calendering sheet molding machine. In Table 2, additives are included in parts by weight relative to the copolymer.

Example 1 Example 2 Example 3 Example 4 Resin of Preparation Example 1 100 - - - Resin of Preparation Example 2 - 100 - - Resin of Preparation Example 3 - - 100 Resin of Preparation Example 4 - - - 100 Phenolic antioxidants ^{4 )} 0.1 0.1 0.1 0.1 Phosphate-based antioxidants ^{5 )} 0.1 0.1 0.1 0.1 Catalytic neutralizer ^{6 )} 0.05 0.05 0.05 0.05 Nucleating agent (3,4-dimethyl benzylidene sorbitol) 0.2 0.2 0.2 0.2

4) Iganox 1010.

5) Iganox 168

6) Ca-ST (calcium stearate)

< Comparative example  1-5> Preparation of Sheets

In the same manner as in Example, a sheet was prepared in the composition of Table 3 below.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Resin of Preparation Example 5 100 - - - - Resin of Preparation Example 6 - 100 - - - Ethylene-propylene random copolymer ^{1 )} - - 100 90 80 Ethylene-propylene block copolymers ^{2 )} - - - - 20 Metallocene rubber ^{3 )} - - - 10 - Phenolic antioxidants ^{4 )} 0.1 0.1 0.1 0.1 0.1 Phosphate-based antioxidants ^{5 )} 0.1 0.1 0.1 0.1 0.1 Catalytic neutralizer ^{6 )} 0.05 0.05 0.05 0.05 0.05 Nucleating agent (3,4-dimethyl benzylidene sorbitol) 0.2 0.2 0.2 0.2 0.2

1) Ethylene content is 3% by weight (RS401, Samsung Total Co., Ltd.)

2) Ethylene content is 8% by weight (BJ350, Samsung Total Co., Ltd.)

3) metallocene C ₂ -C ₄ rubber (Tafmer, Mitsui Chemicals, Inc.)

4) Iganox 1010

5) Iganox 168

6) Ca-ST (calcium stearate)

< Experimental Example > Evaluation of Physical Properties

MI was measured using the pellets of the resin compositions prepared in Examples and Comparative Examples, and after the ASTM injection specimens were prepared, the physical properties of the injected specimens were measured and shown in Tables 4 and 5. Impact resistance was measured using the sheets prepared in the above Examples and Comparative Examples.

Example
One Example
2 Example
3 Example
4 Melt Index (g / 10min) 4 5 4.5 6 Molecular Weight Distribution (PI) 5.0 5.5 5.5 5.7 Cloudiness (%) 21 20 18 15 Flexural Modulus (kgf / cm ² ) 9,300 8,700 9,200 8,300 Izod impact strength
23 ℃ (kgfcm / cm) 14 17 15 22 Izod impact strength
0 ° C (kgfcm / cm) 6 6 6 8 Shock test (room temperature) (J) 22 29 24 30 Impact test (0 ° C) (J) 8 10 10 11

Comparative Example
One Comparative Example
2 Comparative Example
3 Comparative Example
4 Comparative Example
5 Melt Index (g / 10min) 4 4.5 4 4 3 Molecular Weight Distribution (PI) 5 5 3.5 3.6 3.6 Cloudiness (%) 32 20 21 25 37 Flexural Modulus (kgf / cm ² ) 9,900 6,700 10,500 9,000 12,000 Izod impact strength
23 ℃ (kgfcm / cm) 6 20 6 10 8 Izod impact strength
0 ° C (kgfcm / cm) 3 7 4 5 5 Shock test (room temperature) (J) 15 25 12 13 20 Impact test (0 ° C) (J) 4 16 3 6 7

Test Method: The properties of the polypropylene resin shown in Tables 4 and 5 were measured as follows:

1) Melt index: measured under a load of 2.16 kg at 230 ° C. according to ASTM D1238.

2) Polydispersity index (PI):

The polydispersity index is a method of measuring the molecular weight distribution, and using the crossover modulus (Gc) which is the intersection of the storage modulus and the loss modulus using the rheological properties, The polydispersity index was measured.

3) Haze (haze): measured according to the method of ASTM D1003 (thickness: 2 mm).

4) Flexural modulus: measured according to the method of ASTM D638.

5) Impact strength: Notched Izod specimens were measured according to the method of ASTM D256.

6) Falling impact test: Falling weight impact was measured at room temperature and 0 ℃ using Dynatup (Instron).

According to Tables 4 and 5 above, the polypropylene resin composition of the Example was excellent in impact strength at room temperature and low temperature as well as excellent impact resistance characteristics of the ball fall compared to the composition of the comparative example. In addition, it can be seen that the degree of transparency is also low, excellent transparency.

As described above, it can be seen that the polypropylene resin composition of the present invention has improved transparency and impact resistance and is excellent in moldability, thereby making it easy to form into a sheet.

Claims (11)

First ethylene-propylene random copolymer having an ethylene content of 0.5 to 3.0 wt%; And a second ethylene-propylene random copolymer having an ethylene content of 4.0 to 15% by weight,
Ethylene content of the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer is different polypropylene resin composition.
The method of claim 1,
The first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer are mixed at a weight ratio of 3: 7 to 7: 3.
The method of claim 1,
The polypropylene resin composition, characterized in that the melt index of the polypropylene resin composition is 1 to 15 g / 10 min (230 ℃, 2.16 kg).
The method of claim 1,
Polypropylene resin composition, characterized in that the polydispersity index (PI) of the polypropylene resin composition is 4 to 10.
The method of claim 1,
The polypropylene resin composition further comprises an antioxidant in an amount of 0.1 to 0.5 parts by weight based on the first and second ethylene-propylene random copolymers.
The method of claim 1,
The polypropylene resin composition further comprises a nucleating agent in an amount of 0.01 to 0.5 parts by weight based on the first and second ethylene-propylene random copolymers.
The method of claim 1,
The polypropylene resin composition further comprises a catalyst neutralizing agent in an amount of 0.05 to 2 parts by weight based on the first and second ethylene-propylene random copolymers.
Gas phase polymerization of ethylene and propylene in the presence of a catalyst to produce a first ethylene-propylene random copolymer; And
And a second polymerization step of additionally adding ethylene and propylene in the presence of the first ethylene-propylene random copolymer to prepare a second ethylene-propylene random copolymer by gas phase polymerization. Manufacturing method.
9. The method of claim 8,
After the second polymerization step, the first ethylene-propylene random copolymer and the second ethylene-propylene random copolymer, the method for producing a polypropylene resin composition characterized in that it further comprises a mixing step.
9. The method of claim 8,
Wherein the first polymerization step and the second polymerization step are carried out in a single reactor having a plurality of reactors or two independent zones.
The sheet produced by calendering the polypropylene resin composition of any one of claims 1 to 7.