JP2006083218A - Propylenic resin composition and blow molded article comprising the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylenic resin composition which maintains transparency and rigidity, simultaneously has cold impact resistance, and has a property little whitened, when a high temperature content is charged into a molded article produced from the resin composition. <P>SOLUTION: This resin composition comprises the following components (A), (B) and (C), wherein a (B)/(C) weight ratio is 60/40 to 70/30, and a (A)/[(B)+(C)] weight ratio is 91/9 to 97/3, and a blow-molded article comprising the resin composition. (A) Ethylene-propylene random copolymer having a MFR of 0.1 to 2.0 g/10 min and an ethylene content of 3.0 to 4.0 wt.%. (B) Linear low density polyethylene having a MFR of 0.1 to 5.0 g/10 min and a density of 880 to 925 kg/m<SP>3</SP>measured according to JIS K 7112. (C) (C-1) Ethylene-butene copolymer or (C-2) ethylene-octene copolymer having a MFR of 0.1 to 5.0 g/10 min and a density of 855 to 885 kg/m<SP>3</SP>measured according to ASTM D 792. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene resin composition excellent in transparency, rigidity, cold shock resistance, and heat-resistant whitening resistance when filling a high temperature content, and a blow molded article comprising the composition.

  The propylene-based resin molded body used for food containers and the like rapidly deteriorates in impact resistance under a low temperature environment such as in a freezer. Therefore, if the resin molded body that has become low temperature is accidentally dropped, it may be damaged and the contents may be leaked.

  In general, polypropylene resins are used in a wide range of applications including food containers and pharmaceutical containers because they are excellent in chemical characteristics, physical characteristics, and moldability, and are inexpensive. However, since the polypropylene resin itself does not necessarily have sufficient transparency and mechanical strength characteristics, various nucleating agents are usually added to the polypropylene resin to improve transparency and mechanical strength characteristics, and a large amount of rubber component is used. Although the method of improving impact resistance by adding it is used, there is a problem that transparency is lowered.

  A method of adding a nucleating agent to improve transparency, a method of adding an amorphous ethylene-propylene copolymer to impart impact resistance, or a propylene-ethylene block copolymer as a polypropylene resin In this method, it is difficult to satisfy all of them simultaneously, even if the performance of transparency, rigidity, or impact resistance can be achieved.

  In the prior art, a method of simultaneously balancing impact resistance and rigidity at the expense of transparency is performed. Specifically, instead of imparting impact resistance by adding an ethylene-propylene copolymer, transparency He was forced to sacrifice.

  Japanese Patent No. 2691494 discloses an invention in which low-temperature drop strength is improved without impairing gas barrier properties, transparency, and gloss of a multilayer bottle. This patent is an invention that is supposed to prevent breakage in use in a refrigerator (about 3 ° C.), and a drop body strength test at −5 ° C. was conducted in anticipation of a safety factor, and an improvement in impact strength was found.

  However, the resin composition described in the patent does not guarantee that sufficient cold-resistant strength can be obtained in a severer low-temperature environment such as in a freezer (−15 ° C.), and may be damaged due to dropping or the like. Is done.

Further, the method of adding a rubber component to improve impact resistance has a problem that the container is whitened when filling a high temperature content such as a sauce.
Japanese Patent No. 2691494

  It is an object of the present invention to provide a new propylene-based resin composition that imparts cold shock resistance while maintaining transparency and rigidity, and has a property that hardly causes whitening when filling high temperature contents. To do.

  As means for solving the above-mentioned problems, at least one copolymer selected from linear low density polyethylene, ethylene-butene copolymer and ethylene-octene copolymer is used as a specific ethylene-propylene random copolymer. It has been found that a resin composition containing a coalescence in a specific ratio is effective.

That is, the resin composition of the present invention comprises the following components (A), (B) and (C), the weight ratio of (B) / (C) is 60/40 to 70/30, and (A) / [Total amount of (B) and (C)] is a weight ratio of 91/9 to 97/3, and a blow molded article having excellent rigidity, transparency, cold impact resistance, and heat resistance whitening resistance is obtained from the resin composition. can get.
(A) An ethylene-propylene random copolymer having an MFR at 230 ° C. of 0.1 to 2.0 g / 10 min and an ethylene content of 3.0 to 4.0 wt%.
(B) A linear low-density polyethylene having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to JIS K 7112 of 880 to 925 kg / m ³ .
(C) an ethylene-butene copolymer having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to ASTM D 792 of 855 to 885 kg / m ³ or (C-2 ) Ethylene-octene copolymer.

  According to the present invention, it is possible to obtain a resin composition and a blow molded article excellent in transparency, rigidity, cold shock resistance and heat whitening resistance. These molded products are suitably used for applications such as transparent frozen containers.

  The propylene-based resin composition of the present invention and the blow molded article formed therefrom will be described more specifically.

  The propylene resin composition of the present invention comprises a specific low-density polyethylene (B), a specific ethylene-propylene random copolymer (A), an ethylene-butene copolymer (C-1), and an ethylene-octene copolymer. It is a resin composition containing at least one copolymer selected from polymers (C-2) in a specific ratio. From this resin composition, rigidity, transparency, cold impact resistance, heat resistance whitening resistance An excellent blow molded article can be obtained.

That is, the resin composition of the present invention comprises the following components (A), (B) and (C), the weight ratio of (B) / (C) is 60/40 to 70/30, and (A) / [Total amount of (B) and (C)] is a weight ratio of 91/9 to 97/3, and a blow molded article having excellent rigidity, transparency, cold impact resistance, and heat resistance whitening resistance is obtained from the resin composition. can get.
(A) An ethylene-propylene random copolymer having an MFR at 230 ° C. of 0.1 to 2.0 g / 10 min and an ethylene content of 3.0 to 4.0 wt%.
(B) A linear low-density polyethylene having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to JIS K 7112 of 880 to 925 kg / m ³ .
(C) an ethylene-butene copolymer having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to ASTM D 792 of 855 to 885 kg / m ³ or (C-2 ) Ethylene-octene copolymer.

  Here, when the ratio of the component (C) to the component (B) is (B) / (C)> 70/30, the cold shock resistance is lowered, while when (B) / (C) <60/40. Heat whitening resistance decreases. Further, if the ratio of the total amount of the component (B) and the component (C) to the component (A) is (A) / [total amount of (B) and (C)]> 97/3, the cold shock resistance is lowered. However, when (A) / [total amount of (B) and (C)] <91/9, the heat-resistant whitening property is lowered.

  Hereinafter, each component (A)-(D) which comprises the resin composition of this invention is demonstrated in detail.

(A) Ethylene-propylene random copolymer (A) The ethylene-propylene random copolymer has a melt flow rate value (MFR) at 230 ° C. of 0.1 to 2.0 g / 10 minutes, preferably 0.3 to The amount is 1.5 g / 10 minutes, more preferably 0.8 to 1.5 g / 10 minutes. Moreover, it is desirable that the ethylene content measured by infrared absorption spectrum is 3.0 to 4.0 wt%, preferably 3.0 to 3.5 wt%.

  When the melt flow rate and the ethylene content are within the above ranges, a molded article having a good balance between the fluidity (moldability) and mechanical strength of the resin and having a good appearance can be obtained.

  Such an ethylene-propylene random copolymer is prepared in the presence of a stereoregular olefin polymerization catalyst containing a transition metal compound component such as titanium or zirconium, an organoaluminum component, and an electron donor, a carrier, etc., if necessary. It can be produced by polymerization in the presence of propylene and ethylene according to the required amount. Moreover, it is also possible to manufacture using the metallocene catalyst represented by the patent 3530143.

(B) Linear low density polyethylene (B) The linear low density polyethylene has a melt flow rate value (MFR) at 190 ° C. of 0.1 to 5.0 g / 10 min, preferably 0.5 to 4. 0 g / 10 min. When the MFR is within the above range, the dispersibility in the ethylene-propylene random copolymer becomes good and the transparency is improved. The density of this linear low density polyethylene measured according to JIS K 7112 is 880 to 925 kg / m ³ , preferably 890 to 920 kg / m ³ , and more preferably 900 to 915 kg / m ³ . When the MFR and density are within the above ranges, the dispersibility in the ethylene-propylene random copolymer becomes good and the transparency is improved. Moreover, the deterioration of the heat-resistant whitening property at the time of adding a component (C) is suppressed.

(C) ethylene-butene copolymer or ethylene-octene copolymer (C-1) melt flow rate value (MFR) at 190 ° C. of ethylene-butene copolymer and (C-2) ethylene-octene copolymer ) Is 0.1 to 5.0 g / 10 min, preferably 0.5 to 4.0 g / 10 min. When the MFR is within the above range, the dispersibility in the ethylene-propylene random copolymer becomes good and the transparency is improved.

The density of this copolymer measured according to JIS K 7112 is 855 to 885 kg / m ³ , preferably 855 to 880 kg / m ³ . When the density is in the above range, rubber properties having good cold shock resistance are exhibited.

(D) Nucleating Agent As the (D) nucleating agent according to the present invention, an organic phosphate metal salt is preferably used from the viewpoint of balance of physical properties and transparency. As such a nucleating agent (D), NA-21 or NA-11 manufactured by Asahi Denka can be exemplified as a commercial product, but NA-21 is most preferable from the viewpoint of transparency.

  For products that do not cause odor problems, it is also preferable to use sorbitol nucleating agents. Examples of such a sorbitol nucleating agent include commercially available products such as Gelol MD manufactured by Nippon Nippon Chemical Co., Ltd., Millard 3988 manufactured by Milliken, NC-4 manufactured by Mitsui Chemicals, and the like.

  (D) Specific examples of the nucleating agent include (a) carboxylic acid metal salts such as aluminum p-tert-butylbenzoate, (b) polyhydric alcohols such as dibenzylidene sorbitol and bis (4-methylbenzylidene) sorbitol. Derivatives, (c) organophosphate metal salts such as sodium-2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate, (d) branched olefins such as 3-methyl-1-butene, Polymer nucleating agents such as homopolymers or copolymers of 3,3-dimethyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, etc. Can be mentioned.

  Among these, an organophosphate metal salt is preferable, and by adding the metal salt, a good balance between rigidity and impact resistance of the propylene resin composition can be achieved, and excellent odor characteristics can be obtained. As an organic phosphate metal salt, sodium-2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate represented by the following formula (1), an aluminum compound represented by the following formula (2), etc. Can be illustrated. In particular, the effect of the compound represented by the following formula (1) is high.

ここで、ｔ−Ｂｕは、tert-ブチル基を示す。

Here, t-Bu represents a tert-butyl group.

In the above formula (2), R ¹ and R ² are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, amyl, tert-amyl, hexyl, heptyl, octyl, nonyl, 2-ethylhexyl and the like. X is an alkylene group, and examples thereof include methylene, ethylene, and propylene groups.

Specifically, a compound in which X is a methylene group, R ¹ is a tert-butyl group, R ² is a methyl group, X is a methylene group, and both R ¹ and R ² are tert-butyl groups. Examples thereof include compounds, and further X is a methylene group, and R ¹ and R ² are both tert-amyl groups.

  At the time of preparing the resin composition of the present invention, a composition containing a phosphorus-based antioxidant and / or a phenol-based antioxidant and a neutralizing agent is a preferred embodiment.

  When these are added, phosphorus antioxidant 0.05-0.2 phr, preferably 0.05-0.10 phr, phenol antioxidant 0.05-0.2 phr, preferably 0.05-0. It is preferable to add 10 phr and 0.02-0.2 phr, preferably 0.3-0.7 phr of calcium stearate or hydrotalcite as a neutralizing agent.

  When each component is within the above-mentioned blending range, it is possible to bring out unprecedented characteristics such as improvement of transparency while keeping the fluidity, rigidity and impact resistance of the resin composition at a high level.

Phosphorus antioxidant The phosphorus antioxidant used in the present invention is not particularly limited, and conventionally known phosphorus antioxidants can be used. In addition, it is preferable to use only one type of phosphorus-based antioxidant because the content contamination due to bleeding is small.

  The phosphorus-based antioxidant preferably used in the present invention is a trivalent organic phosphorus compound, specifically, tris (2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6 -Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, and the like.

Phenol-based antioxidant The phenol-based antioxidant used in the present invention is not particularly limited, and a conventionally known phenol-based antioxidant can be used. . Specifically, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,5-di-t-butyl-4-hydroxytoluene and the like can be mentioned.

Neutralizing agent There is no restriction | limiting in particular as a neutralizing agent used by this invention, A conventionally well-known neutralizing agent can be used. Specific examples include calcium stearate and hydrotalcite.

Blow container The propylene-based resin composition of the present invention maintains excellent rigidity and cold impact resistance and has excellent properties with further improved transparency, and can be used as a blow container for cryopreservation. Can do.

  If necessary, other additives and the like are mixed with the above components using a Henschel mixer, V-type blender, tumbler blender, ribbon blender, etc., and then a single screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc. By melting and kneading using the above, it is possible to obtain a high-quality resin composition in which each component and additive are uniformly dispersed and mixed.

  EXAMPLES Next, the present invention will be described through examples, but the present invention is not limited to the examples.

The raw materials used in the examples are as follows.
(A-1) Ethylene-propylene random copolymer:
MFR (230 ° C.); 1.0 g / 10 min. Ethylene content; 3.3 wt%
(A-2) Ethylene-propylene random copolymer MFR (230 ° C.); 1.0 g / 10 minutes Ethylene content; 1.5 wt%
(A-3) Ethylene-propylene random copolymer MFR (230 ° C.); 12 g / 10 minutes Ethylene content; 4.9 wt%
(B-1) Linear low density polyethylene:
MFR (190 ° C.); 3.8 g / 10 min Density; 903 kg / m ³
(B-3) Linear low density polyethylene:
MFR (190 ° C.); 3.8 g / 10 min Density; 913 kg / m ³
(C-1) Ethylene-butene copolymer:
MFR (190 ° C.); 2.0 g / 10 minutes Density; 885 kg / m ³
(C-2) Ethylene-octene copolymer:
MFR (190 ° C.); 0.5 g / 10 min Density; 862 kg / m ³
(D) a nucleating agent;
Hydroxyaluminum-bis [2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate] (main component) Product name NA-21 (manufactured by Asahi Denka)

  In a Henschel mixer, a mixture at a ratio shown in Table 1 consisting of (A-1) an ethylene-propylene random copolymer, (B-1) a linear low density polyethylene, and (C-1) an ethylene-butene copolymer. Furthermore, 0.075 phr of a phosphorus-based antioxidant [Tris (2,4-di-t-butylphenyl) phosphite] and a phenol-based antioxidant [pentaerythritol tetrakis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate] was added at 0.075 phr, calcium stearate was added at 0.05 phr, and (D) nucleating agent NA-21 was added at 0.2 phr, followed by stirring and mixing.

  The mixture is melt-kneaded at a resin temperature of 210 ° C. using a twin-screw extruder (Nihon Steel Works high-speed twin-screw continuous mixer CIM-50), the kneaded product is extruded, cooled in water, cut, and polypropylene resin A pellet of the composition was obtained.

  Next, test pieces (length 130 mm × width 120 mm × thickness 2 mm) for haze and high-speed surface impact tests were prepared by injection molding at 250 ° C. and a mold temperature 40 ° C. using the pellets.

  Moreover, the test piece preparation sheet | seat (240 mm x 240 mm x thickness 3mm) for a bending elastic modulus and a heat-resistant whitening test was produced at 230 degreeC with the press molding machine using the pellet. Using these specimens, haze, high-speed surface impact absorption energy, flexural modulus, and heat resistance whitening resistance were measured. The results are shown in Table 1.

Detailed physical property measuring methods in the present invention are shown below.
(A) Ethylene content A press sheet having a thickness of 500 μm is prepared with a press molding machine set at 210 ° C., measured with a Perkin Elmer FT-IR1650 type measuring instrument, and obtained from a calibration curve prepared in advance.
(B) MFR
It was measured at a load of 2.16 kg under the temperature condition of 230 ° C. or 190 ° C. by the method of ASTM D-1238. Nitrogen was not introduced into the cylinder, and the pellets were charged directly into the cylinder and melted.
(C) Haze Based on ASTM D1003, measurement was performed using a test piece having a thickness of 2 mm.
(D) High-speed surface impact test
A striker with a load cell having a tip diameter of 1/2 inch is collided with a test piece having a thickness of 2 mm under a predetermined temperature atmosphere at a speed of 1 m / s. A base having a tip diameter (receiving diameter) of 3 inches was used as a receiving base on the back surface of the sample. As a value, the total absorbed energy from yielding to destruction was obtained.
(E) Bending elastic modulus A bending test was conducted according to ASTM D790, and the bending elastic modulus was calculated from the result.
(F) Heat-resistant whitening The press sheet was heated in an oven at 80 ° C. for 10 minutes, and the transparency immediately after taking out from the oven and the transparency before heating were visually compared and evaluated in 5 stages (no whitening ○ >○->△>△-> × remarkable whitening).

  Example 1 was carried out in the same manner as in Example 1 except that (C-2) ethylene-octene copolymer was used instead of (C-1) ethylene-butene copolymer.

  In Example 2, it carried out like Example 2 except having used (B-2) linear low density polyethylene instead of (B-1) linear low density polyethylene.

[Comparative Example 1]
Example 1 was carried out in the same manner as in Example 1 except that (A-2) ethylene-propylene random copolymer was used instead of (A-1) ethylene-propylene random copolymer.

[Comparative Example 2]
The same procedure as in Example 1 was performed except that (A-3) ethylene-propylene random copolymer was used instead of (A-1) ethylene-propylene random copolymer in Example 1.

[Comparative Example 3]
The same procedure as in Example 1 was conducted except that the blending ratio of (B-1) linear low density polyethylene and (C-1) ethylene-butene copolymer was changed in Example 1.

[Comparative Example 4]
In Example 1, the blending amount of (A-1) ethylene-propylene random copolymer and the total blending amount of (B-1) linear low density polyethylene and (C-1) ethylene-butene copolymer This was performed in the same manner as in Example 1 except that the ratio was changed.

[Comparative Example 5]
In Example 1, the blending amount of (A-1) ethylene-propylene random copolymer and the total blending amount of (B-1) linear low density polyethylene and (C-1) ethylene-butene copolymer This was performed in the same manner as in Example 1 except that the ratio was changed.

[Comparative Example 6]
In Example 1, it carried out like Example 1 except having used only (A-1) ethylene propylene random copolymer and (B-1) linear low density polyethylene as a resin component.

[Comparative Example 7]
In Example 1, it carried out like Example 1 except having used only (A-1) ethylene-propylene random copolymer and (C-1) ethylene-butene copolymer as a resin component.

[Comparative Example 8]
In Example 1, it carried out similarly to Example 1 except having used only (A-1) ethylene-propylene random copolymer and (C-2) ethylene-octene copolymer as a resin component.

  From the physical property measurement results shown in Table 1, the polypropylene resin composition according to the present invention is very useful because it has cold impact resistance and heat whitening resistance while maintaining transparency and rigidity.

Claims (6)

It consists of the following components (A), (B) and (C), the weight ratio of (B) / (C) is 60/40 to 70/30, and (A) / [(B) and (C) The total weight of the resin composition is 91/9 to 97/3.
(A) An ethylene-propylene random copolymer having an MFR at 230 ° C. of 0.1 to 2.0 g / 10 min and an ethylene content of 3.0 to 4.0 wt%.
(B) A linear low-density polyethylene having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to JIS K 7112 of 880 to 925 kg / m ³ .
(C) an ethylene-butene copolymer having an MFR at 190 ° C. of 0.1 to 5.0 g / 10 min and a density measured according to ASTM D 792 of 855 to 885 kg / m ³ or (C -2) An ethylene-octene copolymer.   The resin composition which added 0.05-0.50phr of (D) nucleating agents to the resin composition of Claim 1.   The blow molded object shape | molded using the resin composition of Claims 1-2.   It is a blow molded object comprised by the multilayer material, Comprising: At least 1 layer consists of a gas barrier layer, The multilayer blow molded object comprised by the resin composition of Claim 1 or 2 is the outermost layer.   A blow molded article composed of a multilayer material, at least one of which comprises a gas barrier layer, the outermost layer comprises a PET resin, and the other at least one layer comprises the resin composition according to claim 1 or 2. A multilayer blow molded article in which the thickness ratio of the layer made of the resin composition according to claim 1 or 2 has at least 50% of the total thickness.   It is a multilayer blow molded object of any one of Claims 3-5, Comprising: It is a container for foodstuffs and fat liquid, The container characterized by the above-mentioned.