JP2007161879A - Polyethylenic molding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyethylenic molding material having excellent moldability, high fluidity, odors, impact resistance, food safety and excellent gas barrier properties. <P>SOLUTION: The polyethylenic molding material comprises (A) >50 to ≤90 wt.% of polyethylene, (B) 5-30 wt.% of an ethylene-vinyl alcohol copolymer and (C) 5-40 wt.% of a modified polyolefin prepared by grafting at least one kind of monomer selected from the group consisting of an unsaturated carboxylic acid and a derivative thereof on a polyolefin. The polyethylenic molding material is characterized in that the molding material satisfies conditions of(1) ≥30 cm spiral flow at t=2 mm at 190°C molding temperature and 40°C metal mold temperature, (2) 0.910-1.01 g/cm<SP>3</SP>density, (3) ≥100 kJ/m<SP>2</SP>tensile impact value and (4) ≤180 ml×mm/m<SP>2</SP>×day×atm oxygen permeability, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyethylene-based molding material, and in particular, relates to a polyethylene-based molding material having excellent moldability, high fluidity, odor, impact resistance, food safety, and gas barrier properties, and in particular, injection moldability. The present invention relates to a polyethylene-based molding material that can form a container, a container lid, and the like that contain foods that are excellent in resistance to oxygen permeation and have little deterioration in physical properties such as impact resistance.

  Conventionally, polyethylene for low-density polyethylene (LDPE) and linear low-density polyethylene (L-LDPE) by utilizing its flexibility, light weight, and low price on caps for food containers and sealed containers, liquid food bottle caps, etc. System materials are widely used. Such a container is generally formed by injection molding. However, a container made of polyethylene alone has a problem that it cannot be stored for a long time because the contents of food and the like are oxidized due to insufficient gas barrier properties of polyethylene.

Incidentally, in the case of lids for food containers, in recent years, so-called one-piece lids, in which the score and hinges are integrated, have become mainstream in order to improve production efficiency and reduce costs, and linear low-density polyethylene is generally used. For example, (a) at a temperature of 190 ° C., MFR at a load of 2.16 kg is 6 to 40 g / 10 min, (b) density is 0.910 to 0.930 g / cm ³ , and (c) folding strength is 3000 times. As described above, (d) tear strength is 1 kg / mm or more and 10 kg / mm or less, (e) volatile content is 80 ppm or less, (f) Vicat softening point is 90 ° C. or more, and (g) no peeling is observed even after repeated bending tests. (H) A polyethylene resin having a stress crack resistance (ESCR) of 5 hours or more was proposed, and a one-piece container lid was made possible (see, for example, Patent Document 1). However, in order to fill foods and the like, there is a demand for further improvement in the ability to prevent oxidative deterioration of containers and container lids in order to prevent oxidative deterioration of the contents.
Further, a gas barrier cap characterized in that it is molded from a resin composition comprising, if necessary, polyethylene and a carboxylic acid-modified polyethylene adhesive resin to an ethylene-vinyl alcohol copolymer or an ethylene-vinyl acetate copolymer saponified product. Is disclosed (for example, see Patent Document 2). However, there are many practical problems in developing this in various food containers. Furthermore, (a) polyolefin resin and (b) ethylene-vinyl alcohol copolymer are composed of resin compositions having a relationship of 55 to 95% by volume and 45 to 5% by volume, respectively, and form a specific phase structure An injection-molded article excellent in permeation resistance of chemicals and gases is disclosed, and can be applied as a material for containers and container lids (see, for example, Patent Document 3). However, generally, if a large amount of a barrier resin is added, the barrier property is improved, but the product becomes brittle and has many practical problems.
JP 2005-60517 A Japanese Patent Publication No.7-112865 JP 2002-249595 A

  In view of the above problems, the object of the present invention is excellent in moldability, high fluidity, odor, impact resistance, food safety and gas barrier properties, in particular, excellent in injection moldability and oxygen permeation prevention. Another object of the present invention is to provide a polyethylene-based molding material that is excellent in properties and has little deterioration in physical properties such as impact resistance, and in particular, a polyethylene-based molding material that can mold a container for storing food, a container lid, and the like.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a polyethylene-based material that contains a specific amount of ethylene-vinyl alcohol copolymer and a modified polyolefin in a specific polyethylene and satisfies specific characteristics. The present invention has been found out that it can be a molding material having excellent moldability, high fluidity, odor, impact resistance, food safety and gas barrier properties.

That is, according to the first aspect of the present invention, a polyethylene-based molding comprising the following components (A) to (C) and satisfying the conditions of the following characteristics (1) to (4): Material is provided.
Component (A) Polyethylene having a melt flow rate of 0.1 to 100 g / 10 min and a density of 0.910 to 0.940 g / cm ^{3 at} a temperature of 190 ° C. and a load of 2.16 kg: more than 50% by weight and 90% by weight or less Component (B) ethylene-vinyl alcohol copolymer: 5 to 30% by weight
Component (C) Modified polyolefin grafted with at least one monomer selected from the group consisting of unsaturated carboxylic acids and derivatives thereof on polyolefin: 5 to 40% by weight
Characteristic (1) Spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C. is 30 cm or more Characteristic (2) Density is 0.910 to 1.01 g / cm ³
Characteristic (3) Tensile impact value is 100 KJ / m ² or more Characteristic (4) Oxygen permeability is 180 ml · mm / m ² · day · atm or less

  According to a second invention of the present invention, in the first invention, the component (A) is a polyethylene having a tear strength of 0.5 kg / mm or more and 15 kg / mm or less. A system molding material is provided.

According to the third invention of the present invention, in the first or second invention, the component (B) satisfies the following characteristics (b-1) to (b-3): A polyethylene-based molding material is provided which is an alcohol copolymer.
Characteristic (b-1) Melt flow rate at a temperature of 190 ° C. and a load of 2.16 Kg is 1 to 20 g / 10 minutes Characteristic (b-2) Density is 1.10 to 1.20 g / cm ³
Characteristic (b-3) The ethylene copolymerization ratio is 10 to 80 mol%

According to the fourth invention of the present invention, in any one of the first to third inventions, the component (C) satisfies the following conditions (c-1) to (c-2). A polyethylene-based molding material is provided which is a modified polyolefin.
Characteristic (c-1) Melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 50 g / 10 min. Characteristic (c-2) Density is 0.915 to 0.965 g / cm ^3.

  According to a fifth invention of the present invention, in any one of the first to fourth inventions, the component (A) is an ethylene / α-olefin copolymer polymerized with a metallocene catalyst in 30 to 30 There is provided a polyethylene-based molding material comprising 100% by weight, and the remaining 70 to 0% by weight is made of high-pressure low-density polyethylene.

  According to a sixth invention of the present invention, in any one of the first to fifth inventions, the modified polyolefin of the component (C) is at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof. A polyethylene-based molding material is provided in which the graft ratio of the monomer is 0.001 to 5% by weight.

  According to the present invention, a polyethylene-based molding material excellent in moldability, high fluidity, odor, impact resistance, food safety, and gas barrier properties can be obtained, particularly excellent in injection moldability and preventing oxygen permeation. A polyethylene-based molding material for containers and container lids that is excellent in properties and has little deterioration in physical properties such as impact resistance can be obtained.

The present invention includes (A) polyethylene having a melt flow rate of 0.1 to 100 g / 10 min and a density of 0.910 to 0.940 g / cm ^{3 at} a temperature of 190 ° C. and a load of 2.16 kg, and (B) ethylene-vinyl. It contains a modified polyolefin obtained by grafting at least one monomer selected from the group consisting of an alcohol copolymer, (C) an unsaturated carboxylic acid and a derivative thereof onto a polyolefin. Characteristics (1) Molding temperature 190 ° C., mold temperature 40 Spiral flow at t = 2 mm at 30 ° C. is 30 cm or more, characteristic (2) density is 0.910 to 1.01 g / cm ³ , characteristic (3) tensile impact value is 100 KJ / m ² or more, characteristic (4) oxygen permeability Is a polyethylene-based molding material satisfying 180 ml · mm / m ² · day · atm or less. Hereinafter, the present invention will be described in detail for each item.

1. Component of polyethylene-based molding material (A) Polyethylene having a melt flow rate of 0.1 to 100 g / 10 min and a density of 0.910 to 0.940 g / cm ^{3 at} a temperature of 190 ° C. and a load of 2.16 kg. (A) Polyethylene having a melt flow rate of 0.1 to 100 g / 10 min and a density of 0.910 to 0.940 g / cm ^{3 at} a temperature of 190 ° C. and a load of 2.16 kg is used as a low-density polyethylene. An ethylene / α-olefin copolymer of ethylene and one or more comonomers selected from ethylene or an α-olefin having 4 to 18 carbon atoms is preferable. Is included. Representative examples of the α-olefin used for the copolymer include 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like.

The melt flow rate of polyethylene (A) used in the present invention at a temperature of 190 ° C. and a load of 2.16 Kg is 0.1 to 100 g / 10 min, preferably 6 to 50 g / 10 min, more preferably 8 to 20 g / 10 min. If the melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is less than 0.1 g / 10 min, the moldability tends to be inferior, and if it exceeds 100 g / 10 min, properties such as impact strength tend to be inferior. The melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg can be adjusted by the polymerization temperature, the use of a chain transfer agent, etc., and a desired product can be obtained.
Here, the melt flow rate at a temperature of 190 ° C. and a load of 2.16 Kg is a value measured according to JIS-K6922-2: 1997.

The density of polyethylene (A) used in the present invention is 0.910 to 0.940 g / cm ³ , preferably 0.918 to 0.935 g / cm ³ . If the density is less than 0.910 g / cm ³ , the rigidity is inferior and the molded article is likely to be deformed, and if it exceeds 0.940 g / cm ³ , the score cutting property tends to be lowered. The density can be changed depending on the type and amount of the comonomer copolymerized with the olefin, and a desired one can be obtained.
Here, the density is a value measured according to JIS-K6922-1,2: 1997.

The tear strength of the polyethylene (A) used in the present invention is preferably from 0.5 kg / mm to 15 kg / mm, more preferably from 1.0 kg / mm to 10 kg / mm. If the tear strength is less than 1 kg / mm, it is easily teared by unnecessary stress, and if it exceeds 10 kg / mm, it tends to be difficult to tear even if the score is on. The tear strength can be adjusted by increasing or decreasing the melt flow rate and density, and the tear strength can be increased by increasing the density or decreasing the melt flow rate.
Here, the tear strength is a value measured according to JIS-K7128-3 using a 120 × 120 × 2 mm plate molded at 190 ° C. as a test piece.

  The method for producing component (A) used in the present invention is not particularly limited as long as the above physical properties are satisfied, and the production method and the like are not particularly limited. It can be produced by a production process such as a polymerization method, a solution polymerization method, a slurry polymerization method, or a high-pressure ion polymerization method.

Among the components (A), the high-pressure method low-density polyethylene mentioned as a preferable one is a low-density polyethylene produced by a high-pressure radical polymerization method. For example, the pressure ranges from 500 to 3500 Kg / cm ² G, and the polymerization temperature is It can be produced in an autoclave type or tubular type reactor by radical polymerization using oxygen or an organic peroxide as a polymerization initiator in the range of 100 to 400 ° C. The high pressure radical process low density polyethylene preferably has a density of 0.915 to 0.925 g / cm ³ , a temperature of 190 ° C., and a melt flow rate of 10 to 50 g / 10 min at a load of 2.16 kg.

  Further, as the component (A), polyethylene produced by a so-called metallocene catalyst is preferable. This is because ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a single site (single site) catalyst containing an organic cyclic compound having a conjugated double bond and a transition metal compound of Group IV of the periodic table. Preferred are those that copolymerize.

  A typical example of the single-site catalyst is a method of producing using a catalyst obtained by mixing the compounds of the following catalyst component (a1) to catalyst component (a4). The details will be described below.

Catalyst component (a1): Compound represented by general formula (1) Me ¹ R ¹ _p R ² _q (OR ³ ) _r X ¹ _4-pqr (1)
(In the formula, Me ¹ represents zirconium, titanium, and hafnium, R ¹ and R ³ each represent a hydrocarbon group having 1 to 24 carbon atoms, R ² represents a 2,4-pentanedionato ligand or a derivative thereof, benzoyl Methanato ligand, benzoylacetonato ligand or derivative thereof, X ¹ represents a halogen atom, and p, q and r are 0 ≦ p ≦ 4, 0 ≦ q ≦ 4, 0 ≦ r ≦ 4, 0 ≦ p + q + r ≦ 4 is an integer indicating a range.

In General Formula (1), Me ¹ represents zirconium, titanium, or hafnium, but the type of these transition metals is not limited to any one, and a plurality of them can be used. R ¹ and R ³ are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group and butyl group; alkenyl groups such as vinyl group and allyl group; phenyl group, tolyl group, xylyl group, mesityl group, indenyl group and naphthyl group Aryl groups such as benzyl groups, trityl groups, phenethyl groups, styryl groups, benzhydryl groups, phenylbutyl groups, neophyll groups, and the like. These may be branched. R ² represents a 2,4-pentanedionate ligand or a derivative thereof, a benzoylmethanato ligand, a benzoylacetonate ligand or a derivative thereof. X ¹ represents a halogen atom such as fluorine, iodine, chlorine and bromine. p, q, and r are integers that satisfy ranges of 0 ≦ p ≦ 4, 0 ≦ q ≦ 4, 0 ≦ r ≦ 4, and 0 ≦ P + q + r ≦ 4, respectively.

Examples of the compound represented by the general formula of the catalyst component (a1) include tetramethylzirconium, tetraethylzirconium, tetrabenzylzirconium, tetrapropoxyzirconium, tetrabutoxyzirconium, tetrabutoxytitanium, tetrabutoxyhafnium, and the like. Zr (OR) ₄ compounds such as tetrapropoxyzirconium and tetrabutoxyzirconium are preferable, and two or more of these may be used in combination.
Specific examples of the 2,4-pentanedionato ligand or derivative thereof, benzoylmethanato ligand, benzoylacetonate ligand or derivative thereof include tetra (2,4-pentandionato) zirconium. , Tri (2,4-pentanedionato) chloride zirconium, di (2,4-pentandionato) dichloride zirconium, (2,4-pentandionato) trichloride zirconium, di (2,4-pentandionato) Diethoxide zirconium, di (2,4-pentanedionato) di-n-propoxide zirconium, di (2,4-pentandionato) di-n-butoxide zirconium, di (2,4-pentane) Diato) dibenzylzirconium, di (2,4-pentanedionato) dineophilylzirconium, tetra (gibe) Zoylmethanato) zirconium, di (dibenzoylmethanato) diethoxide zirconium, di (dibenzoylmethanato) di-n-propoxide zirconium, di (dibenzoylmethanato) di-n-butoxidezirconium, di (dibenzoylacetonato) ) Dietoxide zirconium, di (dibenzoylacetonato) di-n-propoxide zirconium, di (dibenzoylacetonato) di-n-butoxide zirconium and the like.

Catalyst component (a2): Compound represented by general formula (2) Me ² R ⁴ _m (OR ⁵ ) _n X ² _zm-n (2)
(In the formula, Me ² is a group I-III element in the periodic table, R ⁴ and R ⁵ are each a hydrocarbon group having 1 to 24 carbon atoms, X ² is a halogen atom or a hydrogen atom (where X ² is a hydrogen atom) In this case, Me ² is limited to the group III element of the periodic table), z is the valence of Me ² , and m and n are in the range of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively. And an integer of 0 ≦ m + n ≦ z.)

In the general formula (2), Me ² represents a group I to III element of the periodic table, and is lithium, sodium, potassium, magnesium, calcium, zinc, boron, aluminum or the like. R ⁴ and R ⁵ are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8, specifically a methyl group, an ethyl group, a propyl group, an isopropyl group, Alkyl group such as butyl group; alkenyl group such as vinyl group and allyl group; aryl group such as phenyl group, tolyl group, xylyl group, mesityl group, indenyl group and naphthyl group; benzyl group, trityl group, phenethyl group and styryl group Aralkyl groups such as benzhydryl group, phenylbutyl group and neophyll group. These may be branched. X ² represents a halogen atom such as fluorine, iodine, chlorine and bromine or a hydrogen atom. However, when X ² is a hydrogen atom, Me ² is limited to a group III element of the periodic table exemplified by boron, aluminum and the like. Z represents the valence of Me ² , and m and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 ≦ m + n ≦ z.

Catalyst component (a3): Organic cyclic compound having a conjugated double bond The organic cyclic compound having a conjugated double bond of the catalyst component (a3) is cyclic and has 2 or more, preferably 2 to 4, conjugated double bonds, More preferably, a cyclic hydrocarbon compound having one or two or more rings having 2 to 3 and a total carbon number of 4 to 24, preferably 4 to 12; A cyclic hydrocarbon compound substituted with 6 hydrocarbon residues (typically an alkyl or aralkyl group having 1 to 12 carbon atoms); 2 or more, preferably 2 to 4 conjugated double bonds, More preferably, an organosilicon compound having a cyclic hydrocarbon group having 1 or 2 or more rings having 2 to 3 rings and a total carbon number of 4 to 24, preferably 4 to 12; 1 to 6 hydrocarbon residues or al An organosilicon compound substituted with a potassium metal salt (sodium salt or lithium salt) is included. Particularly preferred are those having a cyclopentadiene structure in any of the molecules. Suitable examples of the compound include cyclopentadiene, indene, azulene, or alkyl, aryl, aralkyl, alkoxy, or aryloxy derivatives thereof. Moreover, the compound which these compounds couple | bonded (bridge | crosslinked) via the alkylene group (The carbon number is 2-8 normally, Preferably 2-3) is also used suitably.

The organosilicon compound having a cyclic hydrocarbon group can be represented by the general formula (3).
A _L SiR _4-L (3)
(In the formula, A represents a cyclic hydrocarbon group, R represents a hydrocarbon residue having 1 to 24 carbon atoms or hydrogen, and L is 1 ≦ L ≦ 4.)

  In the general formula (3), A represents the cyclic hydrocarbon group exemplified by a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, and a substituted indenyl group, and R represents a methyl group, an ethyl group, and a propyl group. An alkyl group such as isopropyl group and butyl group; an alkoxy group such as methoxy group, ethoxy group, propoxy group and butoxy group; an aryl group such as phenyl group; an aryloxy group such as phenoxy group; an aralkyl group such as benzyl group; Represents a hydrocarbon residue or hydrogen having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, and L is 1 ≦ L ≦ 4, preferably 1 ≦ L ≦ 3.

  Specific examples of the organic cyclic hydrocarbon compound of the catalyst component (a3) include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, 1,3-dimethylcyclopentadiene, indene, 4-methyl-1-indene, 4,7- Cyclopolyene having 5 to 24 carbon atoms or substituted cyclopolyene such as dimethylindene, cycloheptatriene, cyclooctatetraene, azulene, fluorene, methylfluorene, monocyclopentadienylsilane, biscyclopentadienylsilane, triscyclo Examples include pentadienylsilane, monoindenylsilane, bisindenylsilane, and trisindenylsilane.

Catalyst component (a4): Modified organoaluminum oxy compound and / or boron compound containing Al—O—Al bond The modified organoaluminum oxy compound containing the Al—O—Al bond of catalyst component (A4) is an alkylaluminum compound. By reacting with water, a modified organoaluminum oxy compound usually referred to as aluminoxane is obtained, and usually contains 1 to 100, preferably 1 to 50 Al—O—Al bonds in the molecule. The modified organoaluminum oxy compound may be linear or cyclic.
The reaction between organoaluminum and water is usually carried out in an inert hydrocarbon. As the inert hydrocarbon, aliphatic, alicyclic and aromatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, benzene, toluene and xylene are preferable. The reaction ratio (water / Al molar ratio) between water and the organoaluminum compound is usually 0.25 / 1 to 1.2 / 1, preferably 0.5 / 1 to 1/1.

  Examples of the boron compound of the catalyst component (a4) include triethylaluminum triethylaluminum triethylammonium tetra (pentafluorophenyl) borate, dimethylanilinium dimethylanilinium tetra (pentafluorophenyl) borate tetra (pentafluorophenyl) borate. ) Borate, butylammonium tetra (pentafluorophenyl) borate, N, N-dimethylanilinium tetra (pentafluorophenyl) borate, N, N-dimethylanilinium tetra (3,5-difluorophenyl) borate and the like.

  The catalyst may be used by mixing and contacting the catalyst component (a1) to catalyst component (a4), but it is preferable to use the catalyst supported on an inorganic carrier and / or a particulate polymer carrier (a5). . Examples of the inorganic carrier and / or particulate polymer carrier (a5) include carbon materials, metals, metal oxides, metal chlorides, metal carbonates or mixtures thereof, thermoplastic resins, thermosetting resins, and the like.

Suitable metals that can be used for the inorganic carrier include iron, aluminum, nickel and the like. Specifically, examples of the oxide include SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO _2, or a mixture thereof, and SiO ₂ — _{al 2 O 3, SiO 2 -V} 2 O 5, SiO 2 -TiO 2, SiO 2 -MgO, etc. SiO 2 _-Cr 2 _{O 3} and the like. Among these, those containing as a main component at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ are preferable. Further, as the organic compound, any of a thermoplastic resin and a thermosetting resin can be used. Specifically, particulate polyolefin, polyester, polyamide, polyvinyl chloride, polymethyl methacrylate, polystyrene, polynorbornene, Examples include various natural polymers and mixtures thereof. The inorganic carrier and / or the particulate polymer carrier can be used as they are, but preferably, these carriers are contacted with an organoaluminum compound or a modified organoaluminum oxy compound containing an Al—O—Al bond as a pretreatment. After that, it can also be used as component (a5).

A preferable polymerization method of component (A) can be produced by a gas phase polymerization method, a slurry polymerization method, a solution polymerization method, etc. substantially free of a solvent in the presence of the catalyst, and substantially oxygen, water, etc. Inactive carbon exemplified by aliphatic hydrocarbons such as butane, pentane, hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, etc. It is produced in the presence or absence of a hydrogen fluoride solvent. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 15 to 350 ° C., preferably 20 to 200 ° C., more preferably 50 to 110 ° C., and the polymerization pressure is usually normal pressure to 7 MPa · Gauge (low to medium pressure method). 70 kg / cm ² G), preferably normal pressure to 2 MPa · Gauge (20 kg / cm ² G), and usually 150 MPa · Gauge (1500 kg / cm ² G) or less in the high pressure method. The polymerization time is usually from 3 minutes to 10 hours, preferably from about 5 minutes to 5 hours in the case of the low and medium pressure method. In the case of the high pressure method, it is usually 1 minute to 30 minutes, preferably about 2 minutes to 20 minutes. In addition, the polymerization is not particularly limited to a one-stage polymerization method, but also a two-stage or more multi-stage polymerization method in which polymerization conditions such as a hydrogen concentration, a monomer concentration, a polymerization pressure, a polymerization temperature, and a catalyst are different from each other. A particularly preferable production method includes the method described in JP-A-5-132518.

As the component (A), it is particularly preferable to contain at least 30 to 100% by weight of an ethylene / α-olefin copolymer polymerized with a metallocene catalyst, and the remaining 70 to 0% by weight is made of high-pressure low-density polyethylene. Things.
Moreover, you may add an additive, a filler, etc. to the polyethylene of (A) in the range which does not impair the effect of this invention remarkably. As additives, for example, antioxidants (phenolic, phosphorus-based, sulfur-based), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like can be appropriately used in combination of one or more. As the filler, for example, talc or mica can be used. The polyolefin of component (A) may be continuously multistage polymerized, or may be obtained by polymerizing and blending separately. In any case, various additives may be blended with the polyethylene as necessary, and kneaded with a kneading extruder, a Banbury mixer, or the like to obtain a molding material.

  In the polyethylene-based molding material of the present invention, the amount of component (A) is more than 50% by weight and 90% by weight or less, preferably more than 50% by weight and 80% by weight or less. When the blending amount of the component (A) is 50% by weight or less, the moldability is deteriorated, and it becomes brittle and hard, resulting in poor practical performance. When it exceeds 90% by weight, the gas barrier property is not satisfied.

(B) Ethylene-vinyl alcohol copolymer (B) The ethylene-vinyl alcohol copolymer used in the polyethylene-based molding material of the present invention satisfies the following characteristics (b-1) to (b-3). Those that do are preferred.

Property (b-1) Melt Flow Rate It is preferable that the melt flow rate of the ethylene-vinyl alcohol copolymer (B) at a temperature of 190 ° C. and a load of 2.16 kg satisfies 1 to 20 g / 10 minutes. If the melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is less than 1 g / 10 minutes, the moldability is poor, and if it exceeds 20 g / 10 minutes, the gas barrier properties are lowered. The melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg can be changed depending on the polymerization temperature, the use of a chain transfer agent, etc., and a desired product can be obtained.
Here, the melt flow rate at a temperature of 190 ° C. and a load of 2.16 Kg is a value measured according to JIS-K6922-2: 1997.

Characteristic (b-2) Density The density of the ethylene-vinyl alcohol copolymer (B) preferably satisfies 1.10 to 1.20 g / cm ³ . Density is easily deformed molded article poor rigidity is less than 1.10 g / cm ^3, score cutoff property when 1.20 g / cm ³ greater than tends to decrease. The density can be changed depending on the type and amount of the comonomer copolymerized with the olefin, and a desired one can be obtained.
Here, the density is a value measured according to JIS-K6922-1,2: 1997.

Characteristic (b-3) Ethylene copolymerization ratio The ethylene copolymerization ratio of the ethylene-vinyl alcohol copolymer (B) is preferably 10 to 80 mol%, more preferably 20 to 50 mol%. The degree of saponification is preferably 80% or more, and preferably 85% or more. If the ethylene content is less than 10 mol%, the melt moldability tends to deteriorate, whereas if it exceeds 80 mol%, the gas barrier property tends to be insufficient. On the other hand, when the degree of saponification is less than 80%, the gas barrier properties and the thermal stability are likely to deteriorate.

  In the polyethylene-based molding material of the present invention, the amount of component (B) is 5 to 30% by weight, preferably 5 to 25% by weight. When the blending amount of the component (B) is less than 5% by weight, the gas barrier property is not expressed, and when it exceeds 30% by weight, the mechanical properties are deteriorated and it tends to be unusable in practical performance.

(C) Modified polyolefin (C) The modified polyolefin used in the polyethylene-based molding material of the present invention is a modified polyolefin obtained by grafting at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a derivative thereof onto the polyolefin. Those satisfying the conditions (c-1) to (c-2) are preferred.

Characteristic (c-1) Melt Flow Rate The melt flow rate of the modified polyolefin (C) at a temperature of 190 ° C. and a load of 2.16 kg is preferably 0.1 to 50 g / 10 minutes, more preferably 0.15 to 30 g / 10. Minute, particularly preferably 0.2 to 20 g / 10 minutes. When the melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is less than 0.1 g / 10 min, when processing into a molded body, the processing machine motor is overloaded, and thus the production efficiency is lowered, and 50 g / 10 min. If it exceeds 1, the oxygen permeation-preventing property of the molded article may be lowered.
Here, the melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is a value measured according to JIS-K6922-2: 1997.

Characteristic (c-2) Density The density of the modified polyolefin (C) is preferably 0.915 to 0.965 g / cm ³ , more preferably 0.917 to 0.961 g / cm ³ , and particularly preferably 0.00. 920 to 0.957 g / cm ³ . When the density is less than 0.915 g / cm ³ , the rigidity of the molded body is likely to be reduced, and oxygen permeation prevention and oil resistance are likely to be reduced. When the density exceeds 0.965 g / cm ³ , the impact resistance of the molded body is reduced. There is a risk.
Here, the density is a value measured according to JIS-K6922-1,2: 1997.

  The modified polyolefin (C) of the present invention is a modified polyolefin obtained by grafting at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a derivative thereof onto the polyolefin, and the radical generator such as an organic peroxide is added to the polyolefin. Can be obtained by grafting at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a derivative thereof in the presence of.

  The polyolefin used as the raw material for the modified polyolefin is preferably an ethylene homopolymer or a copolymer of ethylene and an α-olefin. As the α-olefin, a linear or branched olefin having 3 to 20 carbon atoms is preferable. For example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene. , 1-decene. Two or more of them may be used in combination. Among these copolymers, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene / 1-octene copolymer are economical. It is preferable from the viewpoint. The polyolefin is not particularly limited in terms of catalyst, process and the like, and can be usually produced by a general method. That is, it can be produced with various polymerization vessels, polymerization conditions and catalysts in each polymerization mode of Ziegler catalyst, single site catalyst, etc., slurry method, solution method, gas phase method, It can be suitably produced by controlling the polymerization conditions such as polymerization temperature and pressure, the cocatalyst, etc. using a specific Ziegler catalyst or single site catalyst described in JP-B-55-14084.

  Examples of unsaturated carboxylic acids and derivatives thereof grafted to the modified polyolefin of the present invention include monobasic unsaturated dicarboxylic acids and dibasic unsaturated carboxylic acids and their metal salts, amides, imides, esters and anhydrides. Of these, the number of carbon atoms of the monobasic unsaturated carboxylic acid is generally 20 or less, preferably 15 or less. Moreover, the carbon number of the derivative is usually at most 20 or less, preferably 15 or less. Further, the carbon number of the dibasic unsaturated carboxylic acid is generally 30 or less, preferably 25 or less. The carbon number of the derivative is usually 30 or less, preferably 25 or less. Among these unsaturated carboxylic acids and derivatives thereof, acrylic acid, methacrylic acid, maleic acid and anhydrides thereof, 5-norbornene-2,3-dicarboxylic acid and anhydrides thereof, and glycidyl methacrylate are particularly preferable. And 5-norbornene acid anhydride are preferred.

  In producing the (C) modified polyolefin of the present invention, a radical initiator can be used. Although the kind is not specifically limited, Preferably an organic peroxide is desirable. As the organic peroxide, those having a half-life decomposition temperature of 100 ° C. or more are suitable. Suitable organic peroxides include dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-di- (t-butylperoxy) hexane, 2,5-dimethyl-2. , 5- (t-butylperoxy) hexane-3, lauroyl peroxide, t-butylperoxybenzoate, and the like.

The (C) modified polyolefin of the present invention is produced by uniformly mixing and processing the above polyolefin, the above unsaturated carboxylic acid and / or derivative thereof, and an organic peroxide. Specifically, a melt kneading method using an extruder, a Banbury mixer, a kneader, etc., a solution method dissolved in an appropriate solvent, a slurry method suspended in an appropriate solvent, or a so-called gas phase grafting method can be mentioned. The grafting temperature is appropriately selected in consideration of the degradation of the polyolefin, the decomposition of the unsaturated carboxylic acid or its derivative, the decomposition temperature of the peroxide used, and the melt kneading method as an example, Usually, it is 190-350 degreeC, and 200-300 degreeC is especially suitable.
Further, in the production of the modified polyolefin (C) of the present invention, for the purpose of improving its performance, as described in JP-A-62-10107, an already known method such as an epoxy during or after the graft modification is used. A method of treating with a compound or a polyfunctional compound containing an amino group or a hydroxyl group, and a method of removing unreacted monomers (unsaturated carboxylic acid and derivatives thereof) and by-product components by heating, washing, etc. are employed. be able to.

  The higher the graft amount of the at least one monomer selected from the group consisting of the unsaturated carboxylic acid and its derivative, the better, but preferably 0.001 to 5% by weight, more preferably 0.1 to 3% by weight. It is. If the graph and amount of the unsaturated carboxylic acid and / or unsaturated carboxylic acid derivative is less than 0.001% by weight, the graft modification becomes insufficient, the dispersion state of the composition components becomes insufficient, and finally The mechanical strength of the resulting molded product may be reduced. On the other hand, if it exceeds 5% by weight, the resulting modified polyolefin may be gelled, deteriorated or colored. The amount of radical initiator added is preferably 0.001 to 0.50% by weight, more preferably 0.005 to 0.30% by weight, and particularly preferably 0.010 to 0.30% by weight. %. When the ratio of the radical initiator is less than 0.001% by weight, it takes a long time to completely perform the graft modification. Or the graft modification of polyolefin may become insufficient, and a component dispersion state may become insufficient. On the other hand, if it exceeds 0.50% by weight, it may be excessively decomposed by a radical initiator or may cause a crosslinking reaction.

  In the polyethylene-based molding material of the present invention, the amount of component (C) is 5 to 40% by weight, preferably 5 to 30% by weight. When the amount of component (C) is less than 5% by weight, the three components (A), (B), and (C) are difficult to disperse, and when it exceeds 40% by weight, the product is likely to deteriorate.

(D) Other components Additives, fillers and the like may be added to the polyethylene-based molding material of the present invention as long as the effects of the present invention are not significantly impaired. Examples of the additives include antioxidants (phenolic, phosphorous, sulfur), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers, and the like, and one or more of these are used in combination as appropriate. be able to. As the filler, for example, talc or mica can be used.

2. Production and Properties of Molding Material The polyethylene-based molding material of the present invention is composed of the above-mentioned component (A), component (B), component (C), and other components as required, in any order. It can be obtained by melt-kneading using an ordinary kneader such as an extruder, twin-screw extruder, super mixer, Henschel mixer, Banbury mixer, roll mixer, Brabender plastograph, kneader. In this case, it is preferable to select a melt-kneading method capable of improving the dispersion of each component, and it is preferable to perform melt-kneading using a twin-screw extruder.
Moreover, the polyethylene-based molding material of the present invention obtained in this way needs to satisfy the following characteristics (1) to (4).

Characteristics (1) Spiral Flow The polyethylene material of the present invention has a spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C. of 30 cm or more, preferably 35 cm or more. Although there is no particular upper limit to this spiral flow, it is generally 100 cm or less. If this spiral flow is less than 30 cm, the moldability is lowered.
Here, the spiral flow uses a mold having a spiral flow path having a width of 10 mm, a thickness of 2 mm, and a longest flow path length of 2000 mm, using an IS-80EPN injection molding machine manufactured by Toshiba Machine Co., Ltd., a set temperature of 190 ° C., and an injection pressure. Adjust the measuring position so that the cushion amount is 1.9 to 2.1 mm at 75 MPa, holding pressure 75 MPa, holding pressure switching position 7 mm, injection time 5 seconds, cooling time 10 seconds, and set the longest flow length of the sample. Measure.

Characteristic (2) Density The polyethylene-based molding material of the present invention has a density of 0.910 to 1.01 g / cm ³ , preferably 0.919 to 1.00 g / cm ³ . Density inferior stiffness is less than 0.910 g / cm ^3, in the case of using the container and the container closure or the like becomes easily deformed, poor flexibility exceeds 1.01 g / cm ^3, which is not preferable for practical use.
Here, the density is measured according to JIS-K6922-1,2: 1997.

Property (3) Tensile Impact Value The polyethylene-based molding material of the present invention has a tensile impact value of 100 KJ / m ² or more, preferably 130 KJ / m ² or more. The tensile impact value has no particular upper limit, but is generally 2000 KJ / m ² or less. When the tensile impact value is less than 100 J / m ² , the impact strength is low, which is not practically preferable.
Here, the tensile impact value is measured according to JIS-K6922-2: 1997.

Characteristic (4) Oxygen permeability The polyethylene-based molding material of the present invention has an oxygen permeability of 180 ml · mm / m ² · day · atm or less, preferably 150 ml · mm / m ² · day · atm or less. When the oxygen permeability exceeds 180 ml · mm / m ² · day · atm, when used in a container or the like, the oxidation of the contents of the container becomes insufficient and long-term storage of foods and the like becomes difficult. In addition, if oxygen permeability is 0.01-180 ml * mm / m < ² > * day * atm, it is employable practically without trouble.
Here, the oxygen permeability is measured under conditions of 40 ° C. and 50% RH based on JIS-K7126. The test piece in the measurement is performed using a 120 × 120 × 1 mm flat plate molded at 190 ° C. and a mold temperature of 40 ° C. with an IS-150E injection molding machine manufactured by Toshiba Machine.

3. Use of molding material Since the polyethylene-based molding material of the present invention satisfies the above-mentioned characteristics (1) to (4), the moldability, high fluidity, odor, impact resistance, food safety, gas barrier Excellent in injection properties, in particular injection moldability and oxygen permeation prevention properties, and also in impact resistance. Therefore, it can be used for applications such as containers and container lids that require such characteristics, and in particular, food oils such as edible oil and wasabi, seasonings, alcoholic beverages, carbonated beverages and beverage containers and container lids, It can be used for applications such as cosmetics and hair cream containers and container lids, and can be suitably used for food containers molded by injection molding and the like and their container lids.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless it exceeds the gist. In addition, the measuring method used in the Example and the used material are as follows.

1. Measuring method (1) Spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C .: using a mold having a spiral flow path having a width of 10 mm, a thickness of 2 mm, and a longest flow path length of 2000 mm, manufactured by Toshiba Machine Co., Ltd. Using an IS-80EPN injection molding machine, with a set temperature of 190 ° C., an injection pressure of 75 MPa, a holding pressure of 75 MPa, a holding pressure switching position of 7 mm, an injection time of 5 seconds, and a cooling time of 10 seconds, the cushion amount is 1.9 to 2.1 mm. The measurement position was adjusted so that the maximum flow length of the sample was measured.
(2) Tensile impact value: Measured according to JIS-K6922-2: 1997.
(3) Oxygen permeability: Measured under conditions of 40 ° C. and 50% RH based on JIS-K7126. The test piece in the measurement was performed using a 120 × 120 × 1 mm flat plate molded at 190 ° C. and a mold temperature of 40 ° C. with an IS-150E injection molding machine manufactured by Toshiba Machine.
(4) Melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg: measured in accordance with JIS-K6922-2: 1997.
(5) Density: Measured according to JIS-K6922-1,2: 1997.
(6) Tear strength: Measured according to JIS-K7128-3 using a 120 × 120 × 2 mm plate molded at 190 ° C. as a test piece.
(7) Flexural modulus: measured in accordance with JIS-K6922-2.
(8) Folding strength: A test piece of 15 × 110 × 1 mm was prepared by injection molding and measured according to JIS-P8115.
(9) Constant strain ESCR: A test piece was cut out from a 120 × 120 × 2 mm plate injection-molded at 190 ° C., and measured according to JIS-K6922-2.

2. Resin (1) (A) Component Linear low-density polyethylene resin (PE-1) produced in Production Example 1, polyethylene by a commercially available Ziegler catalyst (ZN: UJ270 manufactured by Nippon Polyethylene Co., Ltd.), commercially available high-pressure radical method (A1) to (A3) obtained by blending low density polyethylene (LDPE: LJ802 manufactured by Nippon Polyethylene Co., Ltd.) were used. The density and melt flow rate of PE-1, ZN, and LDPE are shown in Table 1, and the compositions and physical property values of (A1) to (A3) are shown in Table 2.

(Production Example 1)
(1) Preparation of solid catalyst To a catalyst preparation apparatus equipped with an electromagnetic induction stirrer, 1000 ml of toluene purified under nitrogen, 26 g of tetrapropoxyzirconium (Zr (OPr) ₄ ), 22 g of indene and 88 g of methylbutylcyclopentadiene were added. While maintaining at 90 ° C., 100 g of tripropylaluminum was added dropwise over 100 minutes, and then reacted at the same temperature for 2 hours. After cooling to 40 ° C., 2424 ml of a toluene solution of methylalumoxane (concentration 3.3 mmol / ml) was added and stirred for 2 hours. Next, 2000 g of silica (surface area 300 m ² / g) fired at 450 ° C. for 5 hours in advance is added, stirred at room temperature for 1 hour, blown with nitrogen at 40 ° C. and dried under reduced pressure to obtain a solid catalyst with good fluidity. It was.
(2) Gas Phase Polymerization Using a continuous fluidized bed gas phase polymerization apparatus, ethylene and 1-hexene were copolymerized at a polymerization temperature of 65 ° C. and a total pressure of 2 MPa · Gauge (20 kgf / cm ² G). The solid catalyst was continuously supplied, and ethylene, 1-hexene, hydrogen and the like were supplied so as to maintain a predetermined molar ratio, and polymerization was performed to obtain an ethylene / 1-hexene copolymer (PE-1). .

(2) Component (B) A commercially available ethylene-vinyl alcohol copolymer (Eval G156 (B1) manufactured by Kuraray Co., Ltd.) having the properties shown in Table 3 was used.

(3) Component (C) The modified polyethylene obtained in Production Examples 2-3 was used. The properties are shown in Table 4.

(Production Example 2)
Polyethylene having properties of a melt flow rate of 3.2 g / 10 min and a density of 0.955 g / cm ³ obtained by copolymerizing ethylene and butene-1 by slurry polymerization using a Ziegler catalyst described in JP-B-55-14084 (D1) To 100 parts by weight, 0.6 parts by weight of maleic anhydride and 0.013 parts by weight of 2,5-dimethyl-di- (t-butylperoxy) hexane are added and mixed with a Henschel mixer. Using a 50 mm single screw extruder manufactured by Machinery Co., Ltd., melt-kneading under the conditions of a screw rotation speed of 50 rpm and a resin temperature of 280 ° C., a modified polyethylene having a melt flow rate of 1.6 g / 10 minutes and a density of 0.955 g / cm ³ ( C1) was obtained.

(Production Example 3)
A melt flow rate of 3.7 g / 10 min and a density of 0.929 g / cm ³ produced by copolymerizing ethylene and hexene-1 in accordance with the production method of the above linear low density polyethylene resin (PE-1) Add 0.6 parts by weight of maleic anhydride and 0.013 parts by weight of 2,5-dimethyl-di- (t-butylperoxy) hexane to 100 parts by weight of polyethylene (D2) having properties, and mix with a Henschel mixer After that, using a 50 mm single screw extruder manufactured by Modern Machinery Co., Ltd., melt kneading under the conditions of a screw rotation speed of 50 rpm and a resin temperature of 280 ° C., a melt flow rate of 2.1 g / 10 minutes, a density of 0.929 g / cm ³ Modified polyethylene (C2) was obtained.

(Examples 1-6)
The components (A) to (C) were blended in the amounts shown in Table 5, and various physical properties were measured. The results are shown in Table 5. As is apparent from Table 5, a product excellent in oxygen permeation prevention properties and excellent mechanical properties such as weld strength was obtained, and the container lid suitability such as folding strength was excellent.

(Comparative Examples 1-4)
The components (A) to (C) were blended in the amounts shown in Table 6 and various physical properties were measured. The results are shown in Table 6. As is clear from Table 6, Comparative Examples 1 and 3 with a small amount of component (B) ethylene-vinyl alcohol are inferior in oxygen permeation-preventing property, and Comparative Examples 2 and 4 with a small amount of component (A) polyethylene are The tensile impact strength (weld strength) was inferior, and the container lid suitability was not sufficient.

  The polyethylene-based molding material of the present invention is excellent in moldability, high fluidity, flexibility, stress crack resistance, low odor, food safety, and has an appropriate balance of hinge durability and tearability, In addition, since it has excellent oxygen permeation preventive properties and no mechanical properties such as a decrease in weld strength, it can be used as a container and a container lid, and is very useful industrially.

Claims (6)

A polyethylene-based molding material comprising the following components (A) to (C) and satisfying the following conditions (1) to (4):
Component (A) Polyethylene having a melt flow rate of 0.1 to 100 g / 10 min and a density of 0.910 to 0.940 g / cm ^{3 at} a temperature of 190 ° C. and a load of 2.16 kg: more than 50% by weight and 90% by weight or less Component (B) ethylene-vinyl alcohol copolymer: 5 to 30% by weight
Component (C) Modified polyolefin grafted with at least one monomer selected from the group consisting of unsaturated carboxylic acids and derivatives thereof on polyolefin: 5 to 40% by weight
Characteristic (1) Spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C. is 30 cm or more Characteristic (2) Density is 0.910 to 1.01 g / cm ³
Characteristic (3) Tensile impact value is 100 KJ / m ² or more Characteristic (4) Oxygen permeability is 180 ml · mm / m ² · day · atm or less   The polyethylene-based molding material according to claim 1, wherein the component (A) is a polyethylene having a tear strength of 0.5 kg / mm or more and 15 kg / mm or less. The polyethylene-based polyethylene according to claim 1 or 2, wherein the component (B) is an ethylene-vinyl alcohol copolymer that satisfies the following conditions (b-1) to (b-3): Molding material.
Characteristic (b-1) Melt flow rate at a temperature of 190 ° C. and a load of 2.16 Kg is 1 to 20 g / 10 minutes Characteristic (b-2) Density is 1.10 to 1.20 g / cm ³
Characteristic (b-3) The ethylene copolymerization ratio is 10 to 80 mol% The polyethylene-based polyethylene according to any one of claims 1 to 3, wherein the component (C) is a modified polyolefin that satisfies the following conditions (c-1) to (c-2): Molding material.
Characteristic (c-1) Melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg is 0.1 to 50 g / 10 min. Characteristic (c-2) Density is 0.915 to 0.965 g / cm ^3.   The component (A) contains 30 to 100% by weight of an ethylene / α-olefin copolymer polymerized with a metallocene catalyst, and the remaining 70 to 0% by weight is made of high-pressure low-density polyethylene. The polyethylene-type molding material of any one of Claims 1-4.   2. The graft ratio of at least one monomer selected from the group consisting of unsaturated carboxylic acids and derivatives thereof in the modified polyolefin of component (C) is 0.001 to 5% by weight. The polyethylene-type molding material of any one of -5.