JP2001151960A - Polypropylene resin composition and container - Google Patents

Abstract

(57) [Problem] To provide a polypropylene-based resin composition which is simultaneously improved in transparency and impact resistance in a well-balanced manner and is suitable for production of containers. SOLUTION: Polypropylene having an MFR of 4 to 50 is 70 to 90% by weight, and an MFR is 0.5 to 40;
And a copolymer of ethylene having a density of 0.890 to 0.915 and an α-olefin having 6 to 20 carbon atoms.
The present invention relates to a resin composition containing 0.1 to 0.3 parts by weight of an organic phosphoric acid ester-based nucleating agent per 100 parts by weight of a resin of 100% by weight. Further, this composition has a ratio (G ′ / G ″) of the storage elastic modulus (G ′) to the loss elastic modulus (G ″) of the dynamic viscoelasticity measurement of 0 at an angular velocity of 0.1 (rad / s). 0.5 or more, and preferably 1 or more when the angular velocity is 10 (rad / s) or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition and a container formed from the composition, and more particularly to a polypropylene resin composition excellent in transparency and impact resistance, and a container produced therefrom. About.

[0002]

BACKGROUND OF THE INVENTION Polypropylene resins are generally used in a wide range of applications, such as food containers and pharmaceutical containers, because they are excellent in chemical properties, physical properties, and moldability, and are inexpensive. I have. However, since polypropylene resin itself does not always have sufficient transparency and mechanical strength properties, various nucleating agents are usually added to polypropylene resin to improve transparency and mechanical strength properties, and rubber components are added. To improve the impact resistance.

However, a nucleating agent additive formulation for improving transparency and an amorphous ethylene
In the propylene copolymer addition formulation or the method using a propylene / ethylene block copolymer as the polypropylene resin, it is possible to achieve either performance of transparency or impact resistance, but it is not possible to satisfy both at the same time. difficult.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polypropylene resin composition capable of simultaneously improving transparency and impact resistance in a well-balanced manner. Another object of the present invention is to provide various containers suitable for food use and pharmaceutical use produced from the resin composition.

[0005]

That is, according to the present invention, 70 to 90% by weight of polypropylene (A) having a melt flow rate of 4 to 50 (g / 10 minutes) and a melt flow rate of 0.5 to 40 (g) are used. / 10 min) and a density of 0.8
Copolymer (B) of ethylene having 90 to 0.915 (g / cm ³ ) and α-olefin having 6 to 20 carbon atoms
The present invention relates to a polypropylene resin composition containing 0.1 to 0.3 parts by weight of an organic phosphate ester nucleating agent represented by the formula (1) or (2) per 100 parts by weight of a resin consisting of 30% by weight. .

[0006]

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[0007]

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(Where R ¹ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are hydrogen or 1 to 10 carbon atoms)
10 hydrocarbon groups, R ² and R ³ may be the same or different, M is a monovalent metal atom,
n is an integer of 1 to 3, and m is 1 or 2. )

In the present invention, in the measurement of the dynamic viscoelasticity of the composition, the ratio (G ′ / G ″) of the storage elastic modulus (G ′) to the loss elastic modulus (G ″) is set to an angular velocity of 0.1.
(Rad / s) is 0.5 or more, and the angular velocity is 10
A polypropylene-based resin composition showing 1 or more when (rad / s) or more is preferable.

Further, the present invention relates to a container formed from the above-mentioned polypropylene-based resin composition and suitable for packaging foods and medicines.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Next, a polypropylene resin composition according to the present invention and a container formed therefrom,
This will be described more specifically.

Polypropylene (A) The polypropylene serving as the component (A) may be a propylene homopolymer or a random copolymer of propylene and an α-olefin. As the α-olefin, olefins having 2 to 10 carbon atoms other than propylene can be used. For example, ethylene, 1-butene, 4-methyl-
Examples thereof include 1-pentene, 1-hexene, and 1-octene, and among them, ethylene is preferable. Α in the copolymer
-The olefin content is within a range that does not cause a decrease in mechanical strength of the polypropylene resin composition, and is usually preferably less than 10% by weight.

This polypropylene is ASTM D-1
Its melt flow rate measured at 230 ° C. under a load of 2.16 kg is 4 to 50, preferably 8 to 30 (g / 10 min) in accordance with H.238. In addition, ¹³ C-NMR
Is 90%
As described above, it is preferable that the content be 94 to 99%.
When the melt flow rate and the isotactic pentad fraction are within the above ranges, the flowability (moldability) of the resin and the balance of mechanical strength are improved, and a molded article having a good appearance is obtained. can get.

The isotactic pentad fraction (m
mmm) indicates the proportion of isotactic chains in pentad units in the polypropylene molecular chain measured using ¹³ C-NMR. Specifically, the ratio of the absorption intensity (Pmmmm) derived from the methyl group at the center of the chain in which five meso-bonds are continuously formed in propylene units to the absorption intensity (Pw) derived from all the methyl groups in the propylene unit, {(Pmmmm) / (Pw)} × 100 (%)

Such a polypropylene is prepared by polymerizing propylene in the presence of a stereoregular olefin polymerization catalyst containing a titanium-based or zirconium-based transition metal compound component, an organoaluminum component, and, if necessary, an electron donor and a carrier. And, if necessary, polymerization in the presence of another α-olefin.

Ethylene / α-olefin copolymer (B) The ethylene / α-olefin copolymer serving as the component (B) is a copolymer of ethylene and an α-olefin having 6 to 20 carbon atoms, Examples of the α-olefin include 1-hexene, 1-heptene, 1-octene, 1-decene and the like, and 1-hexene and 1-octene are particularly preferred. The content of α-olefin is 3 to 20, preferably 5 to 15% by weight, and when it is within this range, the copolymer exhibits rubbery properties.

This copolymer is available from ASTM D-1238.
The melt flow rate measured at 190 ° C. under a load of 2.16 kg is 0.5 to 40, preferably 1 to
30 (g / 10 minutes). ASTM D-15
Density measured in accordance with J.05 is 0.890-0.90
0 (g / cm ³ ). Within this density range, the copolymer is excellent in transparency while maintaining good rubber elasticity.

Such an ethylene / α-olefin copolymer is a steric compound such as a metallocene catalyst containing a metallocene compound in which a compound having a cyclopentadiene skeleton is coordinated to a transition metal such as zirconium metal and an organic aluminum oxy compound. It can be produced by copolymerizing ethylene and an α-olefin in the presence of a regular polymerization catalyst. In particular, an ethylene / α-olefin copolymer produced using a metallocene-based catalyst is suitable as a raw material for a resin composition for containers because of its narrow molecular weight distribution and composition distribution.

Nucleating agent The organophosphate nucleating agent usable in the present invention is a compound represented by the following general formula (1) or (2).

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[0020]

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In the above formula, R ¹ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are hydrogen or 1 carbon atoms.
A hydrocarbon group of 10 to 10, wherein R ² and R ³ may be the same or different, M is a monovalent metal atom, n is an integer of 1 to 3, m Is 1 or 2.

Specific examples of the compound represented by the general formula (1) include sodium-2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate,
2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis- (4,6-di-t-butylphenyl) phosphate , Lithium-2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis (4-i-propyl-6-t-butylphenyl) )
Phosphate, lithium-2,2'-methylene-bis (4
-Methyl-6-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4-ethyl-6-t-butylphenyl) phosphate,

Sodium-2,2'-butylidene-bis (4,
6-di-methylphenyl) phosphate, sodium-2,2'-butylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis (4,6-di-t-butylphenyl) phosphate,
Calcium-bis- (2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate), magnesium-bis [2,2'-methylene-bis (4,6-di-t -Butylphenyl) phosphate], barium-bis [2,2'-
Methylene-bis (4,6-di-t-butylphenyl) phosphate], sodium-2,2'-methylene-bis (4-
Methyl-6-t-butylphenyl) phosphate, sodium-2,2'-methylene-bis (4-ethyl-6-t-butylphenyl) phosphate,

Sodium-2,2'-ethylidene-bis (4
-M-butyl-6-t-butylphenyl) phosphate,
Sodium-2,2'-methylene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-methylene-bis (4,6-di-ethylphenyl) phosphate
G, potassium-2,2'-ethylidene-bis (4,6-di-t-
Butylphenyl) phosphate, calcium-bis [2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2'-ethylidene-bis (4 , 6-Di-t-butylphenyl) phosphate], barium-bis [2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], aluminum-tris [2, 2'-methylene-bis (4,6-di-t-butylfell) phosphate] and aluminum-tris [2,2'-ethylidene-bis (4,6-di-t-
Butylphenyl) phosphate], and two of these
Mixtures of more than one species can be exemplified.

A hydroxyaluminum phosphate compound represented by the general formula (2) is also an usable organic phosphate compound, and particularly, when both R ² and R ³ are t-
A compound represented by the general formula (3), which is a butyl group, is preferable. Here, R ¹ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and m is 1 or 2.

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Particularly preferred organic phosphate compound is a compound represented by the general formula (4). Where R
¹ is a methylene group or an ethylidene group. Specifically, hydroxyaluminum-bis [2,2′-methylene-bis (4,6-di-t-butyl) phosphate] and hydroxyaluminum-bis [2,2 ′
-Ethylidene-bis (4,6-di-t-butyl) phosphate]. These nucleating agents can be used in combination with other nucleating agents.

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The polypropylene resin composition according to the tree fat group formed product present invention include polypropylene (A) 70 to 90, preferably a 80 to 90% by weight, the ethylene · alpha-olefin copolymer (B). 10 to
30, preferably 10 to 20% by weight of resin 10
0.1 parts by weight of the organic phosphate ester-based nucleating agent
To 0.3, preferably 0.2 to 0.3 parts by weight. Here, the total amount of the polypropylene (A) and the ethylene / α-olefin copolymer (B) is 100
Weight%. When each component is within the above-mentioned mixing range, the impact resistance can be improved while maintaining the transparency of the resin composition at a high level.

The composition may contain, if necessary, a phenolic, phosphorus-based or sulfur-based antioxidant, a heat stabilizer, a neutralizer, a weather stabilizer, a lubricant, etc., without departing from the object of the present invention. And the like. After mixing other additives and the like with the above-described components using a Henschel mixer, a V-type blender, a tumbler blender, a ribbon blender, and the like, a single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc. By melt-kneading using the above, a high-quality resin composition in which each component and additive are uniformly dispersed and mixed can be obtained.

In the polypropylene resin composition according to the present invention, polypropylene (A), ethylene-α-
The storage elasticity obtained when the olefin copolymer (B) and the organic phosphate ester nucleating agent are mixed in the above-mentioned amount ratio, and the dynamic viscoelasticity is further measured using a rotary rheometer. The relationship between the modulus (G ′) and the loss elastic modulus (G ″) preferably satisfies the following condition.
That is, the ratio (G ′ / G ″) of the storage elastic modulus (G ′) to the loss elastic modulus (G ″) is an angular velocity of 0.1 (rad / g).
s), it is 0.5 or more, and the angular velocity is 10 (rad /
s) It is desirable to indicate 1 or more in the above.

Here, G ′ and G ″ are measured using a melt viscoelasticity measuring apparatus such as a rotary rheometer while changing the frequency, that is, the angular velocity, while changing the measurement temperature. According to the time-temperature conversion rule,
The data on the lower temperature side than the reference temperature is shifted to the shorter time side, and the data on the higher temperature side than the reference temperature is shifted to the longer time side along the time axis. As a result, G ′ over a long time range called a master curve, A curve showing the change in G "is drawn. From the curve, the ratio of G 'to G"(G' / G ") is calculated.

FIG. 1 shows G ′ (elastic term) (Pa) and G ″ (viscous term) (P) while changing the angular velocity in the temperature range of 170 to 185 ° C. in Examples and Comparative Examples described later.
a) was measured, G ′ and G ″ were plotted on the vertical axis, and the angular velocity (rad / sec) was plotted on the horizontal axis, and the master curve was plotted on the horizontal axis.

Storage modulus (G ') and loss modulus (G ")
With the above relationship, not only is the ethylene / α-olefin copolymer (B) dispersed uniformly in the polypropylene (A), but also the interaction at the interface between the two is increased. It seems to be. Therefore, this resin composition can suppress irregular reflection of light and can obtain a molded article having a low haze, that is, a high transparency.

The container according to the container invention, rigidity produced using means such as blow molding from a resin composition containing the ingredients, transparency, a good vessel impact resistance, its shape Optional, suitable for packaging foods, pharmaceuticals, etc. In particular, when a resin composition having a viscoelastic property in the above-mentioned range is used, a container having more excellent transparency can be molded.

[0034]

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

First, the used raw materials will be described. (A) Propylene homopolymer (A-1): MFR (230 ° C.); 8 (g / 10 min) isotactic pentad fraction measured by ¹³ C-NMR; 0.957 (b) Propylene single weight Merging (A-
2): MFR (230 ° C.); 30 (g / 10 min) isotactic pentad fraction measured by ¹³ C-NMR; 0.956 (c) ethylene / 1-octene copolymer (B-1) : MFR (190 ° C); 15 (g / 10 min) Density (according to ASTM D-1505); 0.895
(G / cm ³ ) (d) Ethylene / 1-octene copolymer (B-2): MFR (190 ° C.); 15 (g / 10 minutes) Density (based on ASTM D-1505); 0.870
(G / cm ³ )

(E) Propylene / ethylene block copolymer Ethylene content: 8% by weight MFR (230 ° C.); 10 (g / 10 min) (f) Nucleating agent: hydroxy represented by the above formula (4) Aluminum-bis [2,2'-methylene-bis (4,6
-Di-t-butylphenyl) phosphate].

The physical properties were measured by the following methods. (A) Haze: 2 according to ASTM D1003
It measured using the mm sheet. (B) Flexural modulus: A flexural test was performed in accordance with ASTM D790, and the flexural modulus was calculated from the results. (C) Izod impact strength: Measured at 23 ° C. with a notch according to ASTM D256.

(D) Dynamic viscoelastic properties: 170, 17 using a rotary rheometer as a melting dynamic viscoelasticity measuring device.
12.5 m diameter at temperatures of 5, 180 and 185 ° C.
m, the lower plate is alternately moved left and right under 10% strain, the angular velocity is changed in the range of 0.01 to 400 (rad / s), G ′ and G ″. A master curve was created from the results and is shown in FIG.

Examples 1 to 3 In a Henschel mixer, propylene homopolymer (A-1) and ethylene 1-
The octene copolymer (B-1) was supplied at the ratio shown in Table 1, and a nucleating agent and a phosphorus-based antioxidant [tris (2,4-di-t-butylphenyl) phosphite] were used as additives. , A neutralizing agent (calcium stearate) and a lubricant (erucamide) were added and mixed with stirring. The mixture was heated to a resin temperature of 190 using a twin screw extruder (40 mmφ).
The mixture was melted and kneaded at ℃, and the kneaded product was extruded to obtain pellets of the polypropylene resin composition.

Next, a sheet-like test piece having a thickness of 2 mm at 230 ° C. and a mold temperature of 40 ° C., and a test piece for bending strength test (ASTM D79) were obtained by injection molding using the pellets at 230 ° C. and a mold temperature of 40 ° C.
0, thickness 3.2mm, length 127mm, width 12.7m
m) and Izod impact test specimens (ASTM
D256, thickness 3.2mm, length 63.5mm, width 1
2.7 mm). Using these test pieces, haze, flexural modulus, and Izod impact strength were measured, and the results are shown in Table 1.

(Comparative Example 1) The results of measuring the physical properties of Example 3 when no nucleating agent was added were also shown in Table 1.

Comparative Example 2 The procedure of Example 3 was repeated, except that the ethylene / 1-octene copolymer (B-2) was used instead of the ethylene / 1-octene copolymer (B-1). The operation was performed in the same manner as described above, and the physical property measurement results were also shown in Table 1.

Comparative Example 3 Propylene homopolymer (A-
2) and ethylene / 1-octene copolymer (B-2)
The operation was performed in the same manner as in Example 1 except for using, and the physical property measurement results were also shown in Table 1.

(Comparative Example 4) The same procedure as in Example 1 was carried out except that only the propylene homopolymer (A-1) was used as the resin. The physical property measurement results are also shown in Table 1. (Comparative Example 5) The same operation as in Example 1 was performed except that only the ethylene / propylene block copolymer was used as the resin. The physical property measurement results are also shown in Table 1.

From the measurement results of the physical properties shown in Table 1, especially when comparing Example 3 with Comparative Examples 2 and 3, the polypropylene resin composition according to the present invention has high transparency and impact resistance. It turns out that those values are balanced. Such a balance between transparency and impact resistance can be obtained by using an ethylene / propylene block copolymer having excellent impact resistance, as can be seen by comparing the physical property measurement results of Comparative Example 5. Absent.

Next, the results of measuring the dynamic viscoelasticity of the propylene-based resin compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 4
The results of measuring the dynamic viscoelasticity of the various resins obtained in the above are also shown in FIG.

From the results of the dynamic viscoelasticity measurement, Example 1 showed that G ′ / G ″ was 0.1 at an angular velocity of 0.1 (rad / s).
7, which is 0.15 in the case of polypropylene not containing the ethylene / α-olefin copolymer shown in Comparative Example 4.
It shows nearly 5 times higher elasticity compared to.

[0048]

[Table 1]

[0049]

The polypropylene composition according to the present invention maintains good transparency since the components (A) and (B) and the nucleating agent are mixed in a specific mixing ratio. It has high rigidity and impact resistance, and its physical properties are well balanced, making it suitable for the production of various packaging containers. Also, among the resin compositions,
In particular, when the viscoelastic property is in a specific range, a container with higher transparency can be provided.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between G ′ and G ″ measured in Example 3 and Comparative Examples 3 and 4, and angular velocity.

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Claims (7)

[Claims] A melt flow rate of 4 to 50 (g / 10
Min) polypropylene (A) of 70 to 90% by weight and a melt flow rate of 0.5 to 40 (g / 10 min);
Per 100 parts by weight of a resin consisting of ethylene having a density of 0.890 to 0.915 (g / cm ³ ) and 10 to 30% by weight of a copolymer (B) of an α-olefin having 6 to 20 carbon atoms And 0.1 to 0.3 parts by weight of an organophosphate nucleating agent represented by the formula (1) or (2). Embedded image Embedded image (Where R ¹ is a divalent hydrocarbon group having 1 to 10 carbon atoms, R ² and R ³ are hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ³ are the same. M may be 1 to 3 valent metal atoms, n is an integer of 1 to 3, and m is 1 or 2.) 2. In the dynamic viscoelasticity measurement of the composition, the ratio (G ′ / G ″) of the storage elastic modulus (G ′) to the loss elastic modulus (G ″) is 0.1 (rad / s). The polypropylene-based resin composition according to claim 1, wherein the polypropylene resin composition has a value of 0.5 or more at the time of (d) and 1 or more at an angular velocity of 10 (rad / s) or more. 3. The method according to claim 1, wherein the ethylene / α-olefin copolymer (B) is an ethylene / 1-hexene copolymer or an ethylene / 1-octene copolymer. The polypropylene-based resin composition as described in the above. 4. The polypropylene resin composition according to claim 1, wherein said ethylene / α-olefin copolymer (B) is a polymer produced by a metallocene catalyst. object. 5. The polypropylene resin composition according to claim 1, wherein the nucleating agent is a compound represented by the formula (3). Embedded image (Here, R ¹ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and m is 1 or 2.) 6. The polypropylene resin composition according to claim 1, wherein the nucleating agent is a compound represented by the formula (4). Embedded image (Here, R ¹ is a methylene group or an ethylidene group.) 7. A container formed from the polypropylene-based resin composition according to any one of claims 1 to 6.