JP2017165937A - Composition and molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition excellent in stress cracking resistance (ESCR) while maintaining tear-off property of high pressure method low density polyethylene (LDPE).SOLUTION: There is provided a composition (X) containing high pressure method low density polyethylene (A) of 70 to 99 pts.mass, a polymer (B) satisfying following requirements (B-1) to (B-3) of 1 to 30 pts.mass, where total of the (A) and the (B) is 100 pts.mass. (B-1) U1 content is 5 to 100 mol% when total content T of a constitutional unit derived from 1-butene (U1), a constitutional unit derived from ethylene (U2) and a constitutional unit derived from propylene (U3) is 100 mol%. (B-2) Content of the U2 is 40 mol% or less based on all constitutional unit amount. (B-3) Glass transition temperature (Tg) measured by a dynamic viscoelasticity measurement is -15°C or less.SELECTED DRAWING: None

Description

  The present invention relates to a composition containing high-pressure low-density polyethylene and a molded article containing the composition.

  High-pressure low-density polyethylene (LDPE) has been widely used as a general-purpose resin, but is known to have poor environmental stress crack resistance (also referred to as stress cracking resistance or ESCR), a surfactant solution. There are problems that cannot be applied to applications that may come into contact with the surface, or applications in which stress is continuously generated.

  On the other hand, it is known that linear low density polyethylene (LLDPE) tends to be superior in ESCR compared to high pressure method low density polyethylene (LDPE). It is also known that high-density polyethylene (HDPE) having a linear molecular structure tends to be superior in ESCR compared to high-pressure low-density polyethylene (LDPE).

  Patent Document 1 discloses the use of a composition of LDPE and an ethylene-α-olefin copolymer for the purpose of improving the ESCR of LDPE. Non-Patent Document 1 refers to the mechanism of the development of environmental stress crack resistance of a composition comprising LDPE and an ethylene / vinyl acetate copolymer.

JP 9-1111063 A

Journal of Applied Polymer Science 2014, 131m 39880

  LLDPE has a problem that its tensile strength is large because of its unique mechanical strength, that is, it tends to be inferior in the tearability or tearability of the molded product (hereinafter referred to as tearability). HDPE and polypropylene have a problem of poor flexibility.

When an ethylene-α-olefin copolymer such as LLDPE is mixed with LDPE to make a composition, the effect of improving the ESCR is recognized depending on the blending ratio, but the tendency to reduce the tearing property is recognized. It was difficult to achieve a good balance of tearing. Further, in the case of the composition disclosed in Non-Patent Document 1 described above, the tearing property is unknown, but there is a concern about a decrease in mechanical properties, particularly impact strength, and a problem of an increase in product weight due to an increase in specific gravity. There are also concerns about long-term stability and hygiene problems such as hygroscopicity and odor.
The subject of this invention is providing the composition which is excellent in stress cracking resistance (ESCR), maintaining the tearability of a high pressure method low density polyethylene (LDPE).

  The present inventors have intensively studied to solve the above problems. As a result, the inventors have found that a composition containing a polymer having a specific composition and physical properties in a specific ratio with respect to the high-pressure process low-density polyethylene can solve the above problems, and has completed the present invention.

The present invention relates to the following [1] to [4].
[1] 70 to 99 parts by mass of a high-pressure method low-density polyethylene (A) and 1 to 30 parts by mass of a polymer (B) satisfying the following requirements (B-1) to (B-3) (however, the (A) And (B) is 100 parts by mass).
(B-1) The total content T of the structural unit (U1) derived from 1-butene, the structural unit (U2) derived from ethylene, and the structural unit (U3) derived from propylene is 100 mol%. When it does, content of said U1 is 5-100 mol%.
(B-2) The content of U2 is 40 mol% or less of the total structural unit amount.
(B-3) The glass transition temperature (Tg) measured by dynamic viscoelasticity measurement is
It is −15 ° C. or lower.

  [2] The composition according to [1], wherein the content of U1 is 50 to 100 mol% in the total content T of 100 mol% of U1 to U3 in the requirement (B-1) (X) ).

  [3] The composition (X) according to the above [1], wherein the content of U1 is 5 to 50 mol% in the total content T of 100 mol% of U1 to U3 in the requirement (B-1). ).

  [4] A molded article containing the composition (X) according to any one of [1] to [3].

  ADVANTAGE OF THE INVENTION According to this invention, the composition excellent in stress cracking resistance (ESCR) can be provided, maintaining the tearability of a high pressure method low density polyethylene (LDPE).

Hereinafter, the composition (X) and the molded product of the present invention will be described in detail.
[Composition (X)]
The composition (X) of the present invention is a high-pressure low-density polyethylene (A) 70 to 99 parts by mass and a polymer (B) 1 to 30 masses satisfying the requirements (B-1) to (B-3) described later. Part. However, the sum of (A) and (B) is 100 parts by mass. Hereinafter, (A) and (B) are also referred to as “component (A)” and “component (B)”, respectively.

  The composition (X) preferably contains 75 to 95 parts by mass of the component (A) and 5 to 25 parts by mass of the component (B), more preferably 80 to 95 parts by mass of the component (A). (B) is contained in the range of 5 to 20 parts by mass, more preferably 80 to 92 parts by mass of the component (A) and 8 to 20 parts by mass of the component (B). However, the sum of (A) and (B) is 100 parts by mass. Such an embodiment is preferable in that both ESCR and tearability can be achieved.

  The composition (X) is a polymer other than the components (A) and (B) (hereinafter referred to as “other polymer (C)” or “ Component (C) ") and an additive for resin (hereinafter also referred to as" additive (D) ") can optionally be included.

  The composition (X) preferably contains 70% by mass or more of components (A) and (B), more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass. Above, especially preferably 98% by mass or more. Such an embodiment is preferable in terms of the appearance of the obtained molded body. The upper limit of the total content of the components (A) and (B) may be 100% by mass, but the composition (X) is a component such as another polymer (C) and / or additive (D). The upper limit is determined by the content of these components.

[High pressure low density polyethylene (A)]
As the high-pressure method low-density polyethylene (A), known ones can be used without restriction. The high-pressure method low-density polyethylene is generally polyethylene obtained by radical polymerization of ethylene under high temperature and high pressure, and the production method is not particularly limited, but for example, 500 to 2000 atmospheres, 150 to 300 A radical polymerization method in which radical polymerization is performed under the condition of ° C. is exemplified, and examples of the polymerization initiator include organic peroxides.

The component (A) preferably has a density measured in accordance with ASTM D1505 in the range of 900 to 925 kg / m ³ , more preferably 910 to 925 kg / m ³ .
Component (A) preferably has a melt flow rate (MFR) measured in the range of 190 ° C. and 2.16 kg load in the range of 0.1 to 50 g / 10 min, more preferably, in accordance with ASTM D1238. Is 1-20 g / 10 min.

[Polymer (B)]
The requirements (B-1) to (B-3) satisfied by the polymer (B) will be described. Moreover, it is preferable that a polymer (B) satisfy | fills the requirements (B-4) and / or (B-5) mentioned later, and these are also demonstrated.

<< Requirement (B-1) >>
Component (B) is 100 mol% in total T of the content of the structural unit (U1) derived from 1-butene, the structural unit (U2) derived from ethylene, and the structural unit (U3) derived from propylene. The content of U1 is 5 to 100 mol%.

  In one embodiment of the component (B), the content of U1 is preferably 50 to 100 mol%, more preferably 70 to 100 mol% in the total T of 100 mol%. Hereinafter, this range is also referred to as “preferable range (1)”. When the content of U1 is in the above range, a composition (X) excellent in ESCR can be obtained, which results in a sufficient amount of crystals formed of 1-butene, resulting in a molded article excellent in crack propagation resistance. This is considered to be because.

  In another embodiment of the component (B), the content of U1 is preferably 5 to 50 mol%, more preferably 5 to 35 mol% in the total T of 100 mol%. Hereinafter, this range is also referred to as “preferable range (2)”. When the content of U1 is in the above range, a composition (X) excellent in ESCR can be obtained. This is a molding in which the amount of crystals formed from ethylene or propylene is in an appropriate range, and as a result, has excellent crack propagation resistance. It is thought to be because it becomes a body. In this case, the content of U3 is preferably 50 to 95 mol%, more preferably 65 to 95 mol% in the total T of 100 mol%.

  Content of each structural unit in a component (B) can be adjusted with each monomer amount added during a polymerization reaction, for example. One of ethylene and propylene may be used, or both may be used in combination. The ratio is not particularly limited.

  The total content of U1, U2 and U3 is usually 90 mol% or more, preferably 95 mol% or more, more preferably 98 mol% or more of the total structural unit amount constituting the component (B). Particularly preferred is 100 mol%. That is, the component (B) may have a structural unit derived from monomers other than 1-butene, ethylene, and propylene as long as the effects of the invention are not impaired. Examples of the other structural unit include a structural unit derived from an α-olefin having 20 or less carbon atoms (excluding 1-butene and propylene). Examples thereof include 1-pentene, 1-hexene, 1-octene and 1-decene.

<< Requirement (B-2) >>
In the component (B), the content of U2 is 40 mol% or less, preferably 30 mol% or less of the total structural unit amount. If it is such an aspect, the tearability and ESCR of the composition (X) obtained will be excellent. This is because the compatibilization of the high-pressure method low-density polyethylene (A) and the polymer (B) is suppressed, and a sea-island structure is formed in which the polymer (B) is an island phase in the composition (X) as described later. This is thought to be easier.

<< Requirement (B-3) >>
Component (B) has a glass transition temperature (Tg) measured by dynamic viscoelasticity measurement of −15 ° C. or lower, preferably −18 ° C. or lower, more preferably −20 ° C. or lower. Although there is no restriction | limiting in particular about a minimum, Usually, it is -80 degreeC. When the glass transition temperature (Tg) is in the above range, a composition (X) having excellent properties for preventing crack propagation can be obtained, which is the effect of stress absorption due to the high mobility of molecular chains. it is conceivable that.

  The temperature at which the loss elastic modulus (E ″) by dynamic viscoelasticity measurement shows a maximum value is defined as the glass transition temperature (Tg). The dynamic viscoelasticity measurement is performed by raising the temperature range of −90 to 200 ° C. at 3 ° C./min in a nitrogen atmosphere. The applied strain is 0.1% and the frequency is 1 Hz.

  The glass transition temperature (Tg) can be adjusted to the above range by adjusting the ratio of U1, U2 and U3. For example, Tg tends to be in the above range by setting the content of U1 within the preferable range (1) of the requirement (B-1). Alternatively, by setting the content of U1 within the preferable range (2) of the requirement (B-1) and the content of U2 within the range of the requirement (B-2), Tg tends to be within the above range.

<< Requirement (B-4) >>
Component (B) preferably has a melt flow rate (MFR) measured in the condition of 190 ° C. and 2.16 kg load in the range of 0.1 to 100 g / 10 min, more preferably, in accordance with ASTM D1238. Is in the range of 0.1-50 g / 10 min. If it is such an aspect, it is thought that a component (B) has sufficient molecular weight to show environmental stress crack resistance. The melt flow rate (MFR) can be adjusted by allowing hydrogen to be present in the polymerization system during the production of the component (B), adjusting the concentration thereof, adjusting the polymerization temperature, and the like.

<< Requirement (B-5) >>
Component (B) is preferably the density measured in accordance with ASTM D1505 is in the range of 830~940kg / m ^3, more preferably 840~920kg / m ^3, more preferably at 850~910kg / m ³ is there.

[Method for producing polymer (B)]
The method for producing the polymer (B) comprises a step of homopolymerizing 1-butene in the presence of the following olefin polymerization catalyst, or copolymerizing 1-butene and at least one selected from ethylene and propylene. Have. Other monomers may be further copolymerized as long as the above-mentioned requirements are satisfied.

  As a method for obtaining component (B), in the presence of an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst, a known polymerization method such as a gas phase method, a bulk method, a slurry method, or a solution method is used. There is a method of polymerizing by. The monomer is preferably polymerized using a metallocene compound (b1) represented by the following formula (1) or (2).

  In addition to the metallocene compound (b1), the catalyst is selected from an organoaluminum oxy compound (b21), a compound (b22) that reacts with the metallocene compound (b1) to form an ion pair, and an organoaluminum compound (b23). It is preferable to contain at least one component (b2). Moreover, the said catalyst may also contain a particulate support (b3) as needed.

<Metalocene compound (b1)>

式（１）および（２）中、Ｒ²は炭化水素基またはケイ素含有炭化水素基であり、Ｒ¹、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、Ｒ⁸、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹、Ｒ¹²はそれぞれ独立に水素、炭化水素基またはケイ素含有炭化水素基であり、Ｒ⁵からＲ¹²までの隣接した置換基は互いに結合して環を形成してもよく、Ａは一部に不飽和結合および／または芳香族環を含んでいてもよい炭素数２〜２０の２価の炭化水素基であり、ＡはＹと共に形成する環を含めて２つ以上の環構造を含んでいてもよく、Ｍは周期表第４族から選ばれる金属であり、Ｙは炭素またはケイ素であり、Ｑはハロゲン、炭化水素基、アニオン配位子または孤立電子対で配位可能な中性配位子から同一または異なる組合せで選ばれ、ｊは１〜４の整数である。

In the formulas (1) and (2), R ² is a hydrocarbon group or a silicon-containing hydrocarbon group, and R ¹ , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently hydrogen, a hydrocarbon group or a silicon-containing hydrocarbon group, and adjacent substituents from R ⁵ to R ¹² may be bonded to each other to form a ring; Is a divalent hydrocarbon group having 2 to 20 carbon atoms which may partially contain an unsaturated bond and / or an aromatic ring, and A represents two or more ring structures including a ring formed with Y M is a metal selected from Group 4 of the periodic table, Y is carbon or silicon, and Q can be coordinated by a halogen, a hydrocarbon group, an anionic ligand or a lone electron pair. The neutral ligands are selected in the same or different combinations, and j is an integer of 1 to 4.

  As a hydrocarbon group, a C1-C20 hydrocarbon group is mentioned, for example, Specifically, a C1-C20 alkyl group, a C3-C20 cycloalkyl group, C7-C20 An arylalkyl group, an aryl group having 6 to 20 carbon atoms, and an alkylaryl group having 7 to 20 carbon atoms, which may include one or more ring structures. Specific examples thereof include methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,1-diethylpropyl, 1-ethyl-1-methylpropyl. Examples include 1,1,2,2-tetramethylpropyl, sec-butyl, tert-butyl, 1,1-dimethylbutyl, cyclohexyl, and phenyl.

  Examples of the silicon-containing hydrocarbon group include an alkylsilyl group and an arylsilyl group having 1 to 4 silicon atoms and 3 to 20 carbon atoms. Specific examples thereof include trimethylsilyl, tert-butyldimethylsilyl, and triphenylsilyl. Is mentioned.

R ² is preferably a sterically bulky hydrocarbon group or a silicon-containing hydrocarbon group, that is, a secondary or tertiary substituent, and more preferably a substituent having 4 or more carbon atoms. Specific hydrocarbon groups include isopropyl, 1,1-dimethylpropyl, 1,1-diethylpropyl, 1-ethyl-1-methylpropyl, 1,1,2,2-tetramethylpropyl, sec-butyl, Examples include tert-butyl and 1,1-dimethylbutyl. Particularly preferred is tert-butyl. Examples of the silicon-containing hydrocarbon group include groups in which some or all of the carbon atoms of the hydrocarbon group are substituted with silicon.

Adjacent substituents from R ⁵ to R ¹² on the fluorene ring may be bonded to each other to form a ring. Examples of such a substituted fluorenyl group include benzofluorenyl and dibenzofluorenyl. The substituents R ⁵ to R ¹² on the fluorene ring are symmetrical from the viewpoint of ease of synthesis, that is, R ⁵ = R ¹² , R ⁶ = R ¹¹ , R ⁷ = R ¹⁰ , R ⁸ = R ⁹ . Preferably, it is unsubstituted fluorene, 3,6-disubstituted fluorene, 2,7-disubstituted fluorene or 2,3,6,7-tetrasubstituted fluorene. Wherein the 3-position on the fluorene ring, 6-position, 2-position, 7-position corresponds to the ^{R 7, R 10, R 6} , R 11 , respectively.

R ³ and R ^{4 in} formula (1) are preferably hydrogen or a hydrocarbon group, and may be the same or different. Specific examples of the hydrocarbon group include those similar to the above. Preferred examples of -Y (R ³ ) (R ⁴ )-in formula (1) include, for example, methylene, dimethylmethylene, diisopropylmethylene, methyl tert-butylmethylene, dicyclohexylmethylene, methylcyclohexylmethylene, methylphenylmethylene. , Diphenylmethylene or dimethylsilylene, diisopropylsilylene.

More preferred Y is carbon.
When R ² in the formula (1) or (2) is a tert-butyl group, R ¹ is preferably a methyl group or an ethyl group, preferably a methyl group. In this case, R ³ and R ^{4 in} the formula (1) are a methyl group or a phenyl group, preferably a methyl group. R ³ and R ⁴ are preferably the same as each other. Further, when R ² in the formulas (1) and (2) is a tert-butyl group and R ¹ is a methyl group, R ^{5 to} R ¹² may be hydrogen. Further, when R ² in the formula (1) is a tert-butyl group and R ¹ is an ethyl group, R ⁵ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹² are hydrogen, and R ⁶ , R ¹¹ Those in which is a tert-butyl group are preferably used.

  In the case of the formula (2), Y is bonded to A which is a divalent hydrocarbon group having 2 to 20 carbon atoms which may partially contain an unsaturated bond and / or an aromatic ring, and cycloalkylidene Group or cyclomethylenesilylene group. Preferable specific examples include cyclopropylidene, cyclobutylidene, cyclopentylidene, and cyclohexylidene.

M in the formulas (1) and (2) is a metal selected from Group 4 of the periodic table, and examples of M include titanium, zirconium, and hafnium. Q is selected in the same or different combination from a halogen, a hydrocarbon group, an anionic ligand, or a neutral ligand capable of coordinating with a lone electron pair. Specific examples of the halogen include fluorine, chlorine, bromine and iodine, and specific examples of the hydrocarbon group include the same as those described above for R ^{1 to} R ¹² . Specific examples of the anionic ligand include alkoxy groups such as methoxy and tert-butoxy, aryloxy groups such as phenoxy, carboxylate groups such as acetate and benzoate, and sulfonate groups such as mesylate and tosylate. Specific examples of neutral ligands that can be coordinated by a lone pair include organophosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine, diphenylmethylphosphine, tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxy. And ethers such as ethane. Among these, Q may be the same or different combinations, but at least one is preferably a halogen or an alkyl group.

<Component (b2)>
Component (b2) is at least one selected from an organoaluminum oxy compound (b21), a compound (b22) that reacts with the metallocene compound (b1) to form an ion pair, and an organoaluminum compound (b23). is there.

<< Ingredient (b21) >>
A conventionally well-known aluminoxane can be used as a component (b21).

<< Ingredient (b22) >>
Examples of the component (b22) include Lewis acids, ionic compounds, borane compounds and carborane compounds described in JP-A-1-501950 and JP-A-2004-51676. Furthermore, heteropoly compounds and isopoly compounds are also included.

  Specifically, triarylboranes such as triphenylborane, tris (o-tolyl) borane, tris (p-tolyl) borane, tris (3,5-dimethylphenyl) borane; and triarylboranes such as trimethylborane and triisobutylborane Alkylborane; compounds having fluorine-containing aryl groups such as tris (4-fluorophenyl) borane, tris (3,5-difluorophenyl) borane, tris (4-fluoromethylphenyl) borane, tris (pentafluorophenyl) borane, etc. A compound having a halogen-containing aryl group: trifluoroborane.

<< Ingredient (b23) >>
As component (b23), for example, organoaluminum compounds represented by _{^{R a m Al (OR b)}} n H p X q , and the like. In the above formula, R ^a and R ^b are each independently a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, X is a halogen atom, m is 0 <m ≦ 3, n Is a number 0 ≦ n <3, p is a number 0 ≦ p <3, q is a number 0 ≦ q <3, and m + n + p + q = 3.

  Specific examples of the component (b23) include, for example, tri-n-alkylaluminum such as trimethylaluminum, triethylaluminum and tri-n-butylaluminum; tri-branched alkylaluminum such as triisobutylaluminum; diisopropylaluminum hydride, diisobutylaluminum hydride and the like And dialkylaluminum hydrides such as isobutylaluminum methoxide and isobutylaluminum ethoxide. Among these, tri-n-alkyl aluminum and tri-branched alkyl aluminum are preferable, and trimethyl aluminum and triisobutyl aluminum are more preferable.

<Particulate carrier (b3)>
Examples of the particulate carrier (b3) include inorganic or organic compounds and particulate solids. Examples of inorganic compounds include porous oxides, inorganic halides, clays, clay minerals, and ion exchange layered compounds. Examples of the organic compound include a particulate α-olefin polymer.

<Polymerization conditions>
The polymerization can be carried out by any of liquid phase polymerization methods such as bulk polymerization, suspension polymerization, and solution polymerization, or gas phase polymerization. In the liquid phase polymerization method, an inert hydrocarbon solvent may be used. Specifically, aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane; cyclopentane, cyclohexane, methylcyclopentane And alicyclic hydrocarbons such as benzene, toluene, xylene and the like; and mixtures of two or more of these. Bulk polymerization using olefins containing 1-butene as a solvent can also be carried out.

  In the above polymerization, so-called multistage polymerization in which the polymerization conditions are changed stepwise can also be performed. For example, it is possible to obtain polymers (B) having various molecular weight distributions by carrying out the polymerization stepwise under two conditions with different amounts of hydrogen used. It is also possible to obtain a polymer (B) having a controlled composition distribution by performing stepwise homopolymerization of 1-butene and copolymerization of 1-butene with other olefins.

In carrying out the polymerization, the component (b1) is usually 10 ⁻⁸ to 10 ⁻² mol, preferably 10 ⁻⁷ to 10 ⁻³ mol, in terms of Group 4 metal atoms in the periodic table, per liter of reaction volume. Used in various amounts. In the component (b21), the molar ratio [Al / M] of the aluminum atom in the component (b21) and the Group 4 metal atom (M) in the periodic table (b1) is usually 0.01 to 5000. The amount is preferably 0.05 to 2000. Component (b22) has a molar ratio [b22 / M] of component (b22) to Group 4 metal atom (M) in the periodic table in component (b1), usually 1 to 10, preferably 1 to 5. Is used in such an amount. Component (b23) has a molar ratio [b23 / M] of component (b23) to group 4 metal atom (M) in the periodic table in component (b1), usually 10 to 5000, preferably 20 to 2000. Is used in such an amount.

The polymerization temperature is usually in the range of −50 to 200 ° C., preferably 0 to 100 ° C., more preferably 20 to 100 ° C. The polymerization pressure is usually under normal pressure to 10 MPa gauge pressure, preferably normal pressure to 5 MPa gauge pressure, and the polymerization reaction can be carried out by any of batch, semi-continuous and continuous methods. . Furthermore, the polymerization can be performed in two or more stages having different reaction conditions.
Hydrogen can be added for the purpose of controlling the molecular weight and polymerization activity of the polymer (B) produced during the polymerization, and the amount is suitably about 0.001 to 100 NL per kg of olefin.

[Other polymer (C)]
As the other polymer (C), a thermoplastic resin different from the high pressure method low density polyethylene (A) and the polymer (B) can be widely used. The content of the other polymer (C) is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less in the total mass of the composition (X). Another polymer (C) may be used individually by 1 type, and may use 2 or more types together.

The thermoplastic resin is not particularly limited,
Thermoplastic polyolefin resin: For example, polyethylene such as low density, medium density and high density polyethylene (excluding high pressure method low density polyethylene (A)), polypropylene such as isotactic polypropylene and syndiotactic polypropylene, poly 4-methyl -1-pentene, poly-3-methyl-1-pentene, poly-3-methyl-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, 1-butene / α-olefin copolymer Copolymer, 4-methyl-1-pentene / α-olefin copolymer (excluding polymer (B) in these), cyclic olefin copolymer, chlorinated polyolefin, and modified polyolefin resin obtained by modifying these olefin resins ,
Thermoplastic polyamide resin: For example, aliphatic polyamide (eg, nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612),
Thermoplastic polyester resin: For example, polyethylene terephthalate, polybutylene terephthalate, polyester elastomer,
Thermoplastic vinyl aromatic resin: For example, polystyrene, ABS resin, AS resin, styrene elastomer (example: styrene / butadiene / styrene block polymer, styrene / isoprene / styrene block polymer, styrene / isobutylene / styrene block polymer, these Hydrogenated product),
Thermoplastic polyurethane; vinyl chloride resin; vinylidene chloride resin; acrylic resin; vinyl acetate copolymer such as ethylene / vinyl acetate copolymer; ethylene / methacrylic acid acrylate copolymer; ionomer; ethylene / vinyl alcohol copolymer; Alcohol; Fluorine resin; Polycarbonate; Polyacetal; Polyphenylene oxide; Polyphenylene sulfide polyimide; Polyarylate; Polysulfone; Polyethersulfone; Rosin resin; Terpene resin and petroleum resin;
Copolymer rubber: for example, ethylene / α-olefin / diene copolymer, propylene / α-olefin / diene copolymer, 1-butene / α-olefin / diene copolymer, polybutadiene rubber, polyisoprene rubber, neoprene Rubber, nitrile rubber, butyl rubber, polyisobutylene rubber, natural rubber, silicone rubber;
Etc. are exemplified.
Part or all of the other polymer (C) may be graft-modified with a polar monomer.

[Additive (D)]
Examples of additives (D) include nucleating agents, antiblocking agents, pigments, dyes, fillers, lubricants, plasticizers, mold release agents, antioxidants, flame retardants, ultraviolet absorbers, antibacterial agents, and surfactants. , Antistatic agent, weathering stabilizer, heat resistance stabilizer, anti-slip agent, foaming agent, crystallization aid, antifogging agent, anti-aging agent, hydrochloric acid absorbent, impact modifier, crosslinking agent, co-crosslinking agent, crosslinking aid Agents, pressure-sensitive adhesives, softeners, and processing aids.

An additive (D) may be used individually by 1 type, and may use 2 or more types together.
Although content of an additive (D) is not specifically limited according to a use within the range which does not impair the objective of this invention, It is 0.001 about each additive mix | blended in the total mass of a composition (X). It is preferable that it is -30 mass%.

[Features of Composition (X)]
As described above, the composition (X) of the present invention has the characteristics of excellent tearability and ESCR. The inventors consider the reason why this characteristic appears as follows. In the composition (X), by forming a sea-island structure in which the high-pressure low-density polyethylene (A) becomes the sea phase and the polymer (B) becomes the island phase, the tensile elongation is suppressed and the tearing property is excellent. When the glass transition temperature (Tg) of the polymer (B) forming the island phase is a specific temperature or less, the tendency of the island phase is secured and the stress applied to the molded body is effective. It is presumed that the occurrence of cracks can be suppressed by relaxing the film.

[Production Method of Composition (X)]
The production method of the composition (X) of the present invention is not particularly limited. For example, the high pressure method low density polyethylene (A), the polymer (B), and other optional components are mixed and then melt-kneaded. can get.

  The method of melt-kneading is not particularly limited, and can be performed using a melt-kneading apparatus such as a commercially available extruder. For example, the temperature of the part that is kneaded in the melt kneader is usually 120 to 250 ° C, preferably 120 to 230 ° C. The kneading time is usually 0.5 to 30 minutes, preferably 0.5 to 5 minutes.

[Molded body]
Various molded articles containing the composition (X) of the present invention can be widely used for conventionally known polyolefin applications. The molded body is obtained by a known thermoforming method such as extrusion molding, injection molding, inflation molding, blow molding, extrusion blow molding, injection blow molding, press molding, vacuum molding, powder slush molding, calendar molding, foam molding, etc. It is done.

  As the molding conditions, general polyethylene molding conditions can be applied. For example, a resin temperature of about 160 to 240 ° C. is suitable for injection molding, 150 to 230 ° C. for blow molding, and about 130 to 240 ° C. for extrusion molding.

  Examples of applications that require tearing include applications as containers that are opened by tearing off a part of a cap or the like. More specifically, examples include food containers, pharmaceutical containers, cosmetic containers, detergent containers, industrial chemical containers, agricultural chemical containers and the like in which the contents are required to have high safety and container sealing. Examples of food containers include liquid seasonings (eg, dressing), beverages, ice cream one-way containers, squeezed containers, confectionery containers such as gum bottles, and container lids for pickled plums and wasabi. Examples of the pharmaceutical container include a single-use eye drop container, a container cap for eye drops and liquid medicine that can be torn when opened, a cap for a tablet container, and a medical solution container for hospital use. Examples of cosmetic containers include creams, lotions, and cleansing containers.

  Examples of applications that require high ESCR in addition to tearing include containers with contents containing surfactants, such as detergent containers, cosmetic containers, and industrial chemical containers. That is, as the molded article of the present invention, a container that contains a surfactant-containing content (e.g., detergent, cosmetic, industrial chemical) and that is used by tearing off the opened portion is preferably used.

EXAMPLES Although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.
[Synthesis Example 1] Propylene / Butene / Ethylene Copolymer (PBER)
A 2000 ml polymerization apparatus sufficiently purged with nitrogen was charged with 917 ml of dry hexane, 85 g of 1-butene, and 1.0 mmol of triisobutylaluminum at room temperature, and then the temperature of the polymerization apparatus was raised to 65 ° C. After pressurizing the pressure to 0.77 MPa, the system internal pressure was adjusted to 0.78 MPa with ethylene. Next, dimethylmethylene (3-tert-butyl-5-methylcyclopentadienyl) fluorenylzirconium dichloride and a toluene solution of methylaluminoxane (manufactured by Tosoh Finechem Co., Ltd.) were mixed to produce aluminum atoms and zirconium. A toluene solution containing atoms in a ratio of aluminum atom / zirconium atom = 300/1 (molar ratio) was prepared. Next, an amount of 0.002 mmol of zirconium atoms (thus an amount of 0.6 mmol of aluminum atoms) in the toluene solution was collected and added to the polymerization apparatus. While maintaining the internal temperature at 65 ° C. and maintaining the internal pressure at 0.78 MPa with ethylene, polymerization was carried out for 20 minutes, and 20 ml of methanol was added to terminate the polymerization. After depressurization, the copolymer was precipitated from the polymerization solution in 2 L of methanol and dried under vacuum at 130 ° C. for 12 hours. The yield of the obtained copolymer was 60.4 g. The above process was scaled up and carried out to obtain a sufficient amount of copolymer.

The obtained copolymer was blended with 500 wtppm of the antioxidant Irganox 1076 and 500 wtppm of Irgafos 168, using a modern machinery (Phi) 40 mm single screw extruder, cylinder temperature 210 ° C, screw rotation speed 50 rpm, kneading time After melt-kneading in 2 minutes, the molten strand discharged from a φ4 mm round hole die was cooled and solidified in a water bath set at 10 ° C., and then the strand cutter (model ST-SG3.0) manufactured by Freedia Macros Co., Ltd. The pellet was obtained by cutting.
Table 1 shows the resins used in Examples and Comparative Examples and the following analytical values. In the table, “-” means no data unless otherwise specified.

[Content of structural unit]
The content of the structural unit was calculated from the ¹³ C-NMR spectrum with the following apparatus and conditions.
Measuring device: Nuclear magnetic resonance device
(AVANCE III cryo-500 type manufactured by Bruker BioSpin Corporation)
Observation nucleus: ¹³ C (125 MHz)
Sequence: Single pulse proton broadband decoupling Pulse width: 5.0 μsec (45 ° pulse)
Number of points: 64k
Repetition time: 5.5 seconds Integration number: 128 times Solvent: o-dichlorobenzene / deuterated benzene (volume ratio: 4/1) mixed solvent Sample concentration: 60 mg / 0.6 mL
Measurement temperature: 120 ° C
Standard value of chemical shift: 29.73 ppm

[Glass transition temperature (Tg)]
Using a dynamic viscoelastic device RSA-III manufactured by TA Instruments Inc., the temperature range of −90 to 200 ° C. was raised at 3 ° C./min in a nitrogen atmosphere. The applied strain was 0.1% and the frequency was 1 Hz. The temperature at which the loss elastic modulus (E ″) showed a maximum value was defined as the glass transition temperature (Tg).

[density]
The density was measured according to ASTM D1505 (density gradient tube method).

[Melt flow rate (MFR)]
The melt flow rate (MFR) was measured under the conditions of 190 ° C. and 2.16 kg load or 230 ° C. and 2.16 kg load in accordance with ASTM D1238.

[Examples 1-4, Comparative Examples 2-4, 6-11]
According to the composition shown in Table 2, the pellets of each resin were mixed (dry blended) at room temperature, then using a modern machinery (Phi) 40 mm single screw extruder, cylinder temperature 210 ° C., screw rotation speed 50 rpm, kneading time After melt-kneading in 2 minutes, the molten strand discharged from a φ4 mm round hole die was cooled and solidified in a water bath set at 10 ° C., and then the strand cutter (model ST-SG3.0) manufactured by Freedia Macros Co., Ltd. The pellet was obtained by cutting. The obtained pellets were evaluated by the following methods. The results are also shown in Table 2.

[Comparative Examples 1, 5, 12]
The resin pellets shown in Table 2 were evaluated by the following methods. The results are also shown in Table 2.

[Preparation of injection specimen]
About the pellets, use an injection molding machine manufactured by Meiki Seisakusho Co., Ltd. (model MEIKI M-50AII-DM, mold clamping force 50 tons), cylinder temperature 210 ° C., mold temperature 30 ° C., and injection pressure 70 MPa. A 3 mm test piece was obtained. The obtained test piece was used for the tensile test and the Shore D hardness measurement.

<Tensile test>
The test piece was conditioned at 23 ° C. for 3 days, and in accordance with ASTM D638, using an Intesco tensile tester (model 2005-5) at 23 ° C., a distance between chucks of 64 mm, and a test speed of 50 mm / min. Tensile modulus (YM), yield point elongation (YEL), yield point strength (YS), elongation at break (EL), and strength at break (TS) were measured. The elongation at yield and the elongation at break were calculated as the elongation between chucks. In Table 2, “−” in YEL and YS means that there was no yield point.

《Shore D hardness》
The condition of the test piece was adjusted at 23 ° C. for 24 hours, and the pressure surface of the durometer was pressed vertically at a constant speed from directly above according to ASTM D2240, and the value immediately after contact was defined as “hardness”.

[Press sheet production]
For the pellets, using a hydraulic hot press machine manufactured by Kansai Roll Co., Ltd., set at 210 ° C., preheating was performed for about 5 minutes, pressurized at 7.5 MPa for 2 minutes, and then another Kansai Roll Co., Ltd. set at 20 ° C. ) Using a manufactured hydraulic hot press, the sample was compressed at 7.5 MPa and cooled for 4 minutes to prepare a measurement sample consisting of a press sheet having a thickness of 2 mm.

《Stress cracking resistance (ESCR)》
Using a punched specimen from a press sheet, the half-break time F50 value was determined.
Bent strip method: ASTM D1693
Chemical solution: Igepearl CO 630
Chemical concentration: 10%
Test temperature: 50 ° C
Notch depth: 0.35mm
Maximum time: 600 hrs

[Melt flow rate (MFR)]
The melt flow rate (MFR) was measured under the conditions of 190 ° C. and 2.16 kg load according to ASTM D1238.

[Evaluation]
As shown in Table 2, the comparative example composition containing no polymer (B) and containing LDPE as the main component had an insufficient ESCR value (Comparative Examples 1-4, 10, 11). Moreover, the comparative example composition which does not contain LDPE and contains LLDPE as a main component had large tensile elongation (Comparative Examples 5-9, 12). On the other hand, since the composition of Example contains LDPE and the polymer (B), the EL value is 130% or less, and the ESCR value is 12 hrs or more, which is excellent in the tearability and ESCR of the molded product. It was.

Claims (4)

High pressure method low density polyethylene (A) 70-99 parts by mass;
1 to 30 parts by mass of the polymer (B) satisfying the following requirements (B-1) to (B-3) (provided that the total of the (A) and (B) is 100 parts by mass). Product (X).
(B-1) The total content T of the structural unit (U1) derived from 1-butene, the structural unit (U2) derived from ethylene, and the structural unit (U3) derived from propylene is 100 mol%. When it does, content of said U1 is 5-100 mol%.
(B-2) The content of U2 is 40 mol% or less of the total structural unit amount.
(B-3) The glass transition temperature (Tg) measured by dynamic viscoelasticity measurement is
It is −15 ° C. or lower.   Composition (X) of Claim 1 whose content of U1 is 50-100 mol% in the said requirement (B-1) in total 100 mol% of content T of U1-U3.   Composition (X) of Claim 1 whose content of U1 is 5-50 mol% in the said requirement (B-1) in total 100 mol% of content T of U1-U3.   The molded object containing the composition (X) of any one of Claims 1-3.