JP2007161881A - 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 and heat resistance. <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) ≥25 cm spiral flow at t=2 mm at 190°C molding temperature and 40°C metal mold temperature, (2) 0.953-1.07 g/cm<SP>3</SP>density, (3) ≥4 kJ/m<SP>2</SP>Charpy impact value and (4) ≤100 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 capable of molding a container and a container lid for containing a food having excellent heat resistance, excellent oxygen permeation-preventing properties, less physical properties such as impact resistance, and excellent heat resistance.

  Conventionally, high density polyethylene (HDPE) has been widely used for food cups, caps for liquid food bottles, etc., taking advantage of its slipperiness, light weight, and low price. Such containers are 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.

By the way, the MFR at a load of 2.16 kg is 0.8 to 5 g / 10 min, the HLMFR at a load of 21.6 kg is 180 g / 10 min or more, the HLMFR / MFR is 80, and it has excellent moldability and shortens the cycle. In addition, the moldability and stress crack resistance of a polyethylene composition for containers (for example, see Patent Documents 1 and 2) whose contents are increased in internal pressure due to carbonated beverages or the like that can increase production efficiency are improved. A polyethylene resin capable of being molded at high speed with a sufficient balance among the cutting property, rigidity, and stress crack resistance has been developed by using the container resin composition. However, in order to fill foods, oxidative degradation prevention performance is required to prevent oxidative degradation of the contents, and polyethylene originally has poor oxygen permeation performance, which is disadvantageous in permeation prevention. It is.
JP 2000-248125 A JP 2002-60559 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 heat resistance, has little deterioration in physical properties such as impact resistance, and is excellent in heat resistance, and in particular, a polyethylene-based molding material that can mold a container for storing food and a container lid.

  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 inventors have found that a molding material having excellent moldability, high fluidity, odor, impact resistance, food safety, gas barrier properties and oxygen permeation prevention properties can be obtained.

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 (MFR) of 0.001 to 100 g / 10 min and a density of 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
Characteristics (1) Spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C. is 25 cm or more. (2) Density is 0.953 to 1.07 g / cm ^3.
Characteristic (3) Charpy impact value is 4 KJ / m ² or more Characteristic (4) Oxygen permeability is 100 ml · mm / m ² · day · atm or less

According to the second invention of the present invention, in the first invention, the component (A) is a polyethylene that satisfies the following conditions (a-1) to (a-3). A featured polyethylene-based molding material is provided.
Property (a-1) Flexural modulus is 800 MPa or more Property (a-2) Constant strain ESCR is 1 hour or more Property (a-3) Vicat softening point is 90 ° C. or more

According to the third invention of the present invention, in the first or second invention, the component (A) is a polyethylene that satisfies the following conditions (a-4) to (a-5). A polyethylene-based molding material is provided.
Characteristic (a-4) Hydrocarbon volatile content is 80 ppm or less Characteristic (a-5) Melt viscosity at a temperature of 200 ° C. and a shear rate of 200 sec ⁻¹ by a capillary rheometer is 500 Pa · sec or less

According to a fourth aspect of the present invention, in any one of the first to third aspects, the component (A) comprises the following components (A-1) and (A-2), and the temperature is 190. There is provided a polyethylene-based molding material characterized in that a melt flow rate (HLMFR) at 100 ° C. and a load of 21.6 kg is 100 to 400 g / 10 min and HLMFR / MFR is 50 to 200.
Component (A-1) HLMFR 0.5-10 g / 10 min, density 0.935 g / cm ³ or more polyethylene resin 10 parts by weight or more and less than 30 parts by weight Component (A-2) MFR 30 g / 10 min or more , More than 70 parts by weight of polyethylene resin having a density of 0.961 g / cm ³ or more and 90 parts by weight or less

According to the fifth invention of the present invention, in any one of the first to fourth inventions, the component (B) satisfies the following characteristics (b-1) to (b-3). A polyethylene-based molding material is provided which is an ethylene-vinyl 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 sixth aspect of the present invention, in any one of the first to fifth aspects, 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 the seventh invention of the present invention, in any one of the first to sixth 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. It is possible to obtain a container and a polyethylene-based molding material for a container lid that are capable of molding a container and a container lid that are excellent in heat resistance, have little deterioration in physical properties such as impact resistance, and are excellent in heat resistance.

The present invention includes (A) polyethylene having a melt flow rate (MFR) of 0.001 to 100 g / 10 min and a density exceeding 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 25 ° C. is 25 cm or more, characteristic (2) density is 0.953 to 1.07 g / cm ³ , characteristic (3) Charpy impact value is 4 KJ / m ² or more, characteristic (4) oxygen permeability Is a polyethylene-based molding material satisfying 100 ml · mm / m ² · day · atm or less. Hereinafter, the present invention will be described in detail for each item.

1. Component of polyethylene molding material (A) Polyethylene molding material having a melt flow rate of 0.001 to 100 g / 10 min and a density exceeding 0.940 g / cm ³ at a temperature of 190 ° C. and a load of 2.16 kg. (A) As a polyethylene having a melt flow rate of 0.001 to 100 g / 10 min and a density exceeding 0.940 g / cm ³ at a temperature of 190 ° C. and a load of 2.16 Kg, high density polyethylene is preferably exemplified. Or an ethylene / α-olefin copolymer with one or more comonomers selected from α-olefins having 4 to 18 carbon atoms. 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 0.001 to 100 g / 10 minutes, preferably 0.5 to 40 g / 10 minutes, more preferably 0.8 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 0.001 g / 10 min, the moldability tends to be inferior, and if it exceeds 100 g / 10 min, characteristics such as stress crack resistance 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 exceeds 0.940 g / cm ³ , and preferably 0.945 to 0.980 g / cm ³ . When the density is 0.940 g / cm ³ or less, the rigidity is inferior and the molded body is easily deformed at a high temperature. 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.

Furthermore, the polyethylene (A) used in the present invention preferably satisfies the following characteristics (a-1) to (a-5).
Characteristic (a-1) Flexural modulus The flexural modulus of polyethylene (A) is preferably 800 MPa or more, preferably 900 MPa or more, and more preferably 1000 MPa or more. When the flexural modulus is less than 800 MPa, the rigidity is lowered, and the molded product is easily deformed particularly at high temperatures. The upper limit value of the flexural modulus is not particularly limited, but is usually 2000 MPa or less. The flexural modulus can be adjusted by increasing or decreasing the melt flow rate and density, and the flexural modulus can be increased by increasing the density or decreasing the melt flow rate.
Here, the flexural modulus is a value measured according to JIS-K6922-2 using a 4 × 10 × 80 mm plate injection-molded at 210 ° C. as a test piece.

Characteristic (a-2) Constant strain ESCR
The constant strain ESCR of polyethylene (A) is preferably 1 hour or longer, more preferably 10 hours or longer. If the constant strain ESCR is less than 1 hour, the durability of the molded product is lowered. The constant strain ESCR can be adjusted by increasing or decreasing the melt flow rate and density, and can be increased by increasing the density or decreasing the melt flow rate.
Here, the constant strain ESCR is a value measured in accordance with JIS-K6922-2 using a test piece cut out from a 120 × 120 × 2 mm plate injection-molded at 190 ° C.

Characteristic (a-3) Vicat softening point The Vicat softening point of polyethylene (A) is preferably 90 ° C or higher, more preferably 100 ° C or higher. If the Vicat softening point is less than 90 ° C., the heat resistance tends to be insufficient, and deformation tends to occur during high temperature filling. The Vicat softening point can be changed by increasing or decreasing the density, and can be increased by increasing the density.
Here, the Vicat softening point is a value measured according to JIS-K7206.

Characteristic (a-4) Hydrocarbon volatile content The hydrocarbon volatile content of polyethylene (A) is preferably 80 ppm or less, and more preferably 50 ppm or less. If the hydrocarbon volatile content exceeds 80 ppm, odor may remain in the container contents. Hydrocarbon volatiles can be reduced by deodorizing treatment, and in particular, the effect of the present invention can be exhibited by performing steam deodorizing treatment. The conditions for the steam treatment are not particularly limited, but it is preferable that the polyethylene is brought into contact with 100 ° C. steam for about 8 hours.
Here, the hydrocarbon volatiles are measured by putting 1 g of polyethylene resin in a 25 ml glass sealed container and analyzing the components in the sealed container after heating at 130 ° C. for 60 minutes by gas chromatography. Value.

Characteristics (a-5) Temperature 200 ° C. by capillary rheometer at a temperature 200 ° C. by capillary rheometer of the melt viscosity of polyethylene shear rate 200 sec ^-1 (A), the melt viscosity shear rate 200 sec ^-1 is less 500 Pa · sec Preferably, it is 400 Pa · sec or less. When the melt viscosity exceeds 500 Pa · sec, the fluidity is lowered and the high-speed moldability is lowered. This melt viscosity can be adjusted by increasing or decreasing the molecular weight of polyethylene, and can be increased by increasing the molecular weight.
Here, the melt viscosity at a temperature of 200 ° C. and a shear rate of 200 sec ⁻¹ using a capillary rheometer was measured using a capillary rheometer manufactured by Intesco, using a capillary with a diameter of 1.0 mm and L / D = 20, and a temperature of 200 ° C. It is a value obtained by measuring the viscosity at a shear rate of 200 sec- ¹ .

  The polyethylene (A) used in the present invention may be a single polyethylene resin, but may be composed of a plurality of, for example, polyethylene resin components having two different physical properties. Preferably, it consists of the following components (A-1) and (A-2), a melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg is 100 to 400 g / 10 minutes, and an HLMFR / MFR is 50 to 50. And a polyethylene resin of 200.

Examples of the component (A-1) constituting the polyethylene (A) include a polyethylene resin having a HLMFR of 0.5 to 10 g / 10 min and a density of 0.935 g / cm ³ or more.
If the HLMFR of the polyethylene resin component (A-1) is less than 0.5 g / 10 minutes, the fluidity tends to be lowered and the moldability tends to be poor, and if it exceeds 10 g / 10 minutes, the stress crack resistance is reduced. . If the density of the polyethylene resin component of component (A-1) is less than 0.935 g / cm ³ , the rigidity will be insufficient. As an upper limit of the density of the polyethylene resin component of the component (A-1), 0.955 g / cm ³ is desirable.

As a component (A-2) which comprises polyethylene (A), MFR is 30 g / 10min or more, and a density is 0.961 g / cm < ³ > or more.
When the MFR of the polyethylene resin component (A-2) is less than 30 g / 10 minutes, the fluidity is lowered. The upper limit of the MFR of the polyethylene resin of the component (A-2) is not particularly limited, but the melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg of the component (A) is 100 to 400 g / 10 minutes, and the HLMFR / MFR is It is selected within a range satisfying 50-200. When the density of the polyethylene resin component (A-2) is less than 0.961 g / cm ³ , the rigidity may decrease. Although the upper limit of the density of the polyethylene resin component of the component (A-2) is not particularly limited, it is usually 0.980 g / cm ³ or less.

Component (A-1) and component (A-2) are blended in such a proportion that component (A-1) is 10 parts by weight or more and less than 30 parts by weight, preferably 20 parts by weight or more and less than 30 parts by weight. -2) is more than 70 parts by weight and 90 parts by weight or less, preferably more than 70 parts by weight and 80 parts by weight or less. When the component (A-1) is less than 10 parts by mass, the stress crack resistance decreases, and when it is 30 parts by mass or more, the moldability decreases.
These polyethylene resin components having two different physical properties may be sequentially polymerized or may be polymerized separately and then blended later.

  The production method of the component (A) used in the present invention is not particularly limited as long as the above physical properties are satisfied, and the polymerization method such as a Ziegler catalyst, a metallocene catalyst, or a chromium catalyst is used. Thus, it can be produced by a production process such as a gas phase polymerization method, a solution polymerization method, a slurry polymerization method, or a high pressure ion polymerization method.

Moreover, it can be set as the polyethylene-type molding material of this invention by superposing | polymerizing separately the polyethylene resin component of a component (A-1) and a component (A-2), respectively, and blending them. Preferably, those obtained by successively polymerizing in a plurality of polymerization reactors connected in series, for example, two polymerization reactors, for reasons such as ease of operation and homogeneity of composition are preferred. As the polymerization catalyst, various catalysts such as the aforementioned Ziegler catalyst, metallocene catalyst, chromium catalyst and the like are used. The polymerization can be carried out in an organic solvent, in a liquid monomer or in the gas phase. In so-called multistage polymerization in which polymerization is performed sequentially in a plurality of polymerization reactors connected in series, for example, a polyethylene resin (base) of a high molecular weight component by (co) polymerizing ethylene or further α-olefin in the first stage ( Component (A)) is produced, and then ethylene and hydrogen are introduced into the polymerization system to prepare a polyethylene resin containing a high molecular weight component and a low molecular weight component.
In the case of multi-stage polymerization, the amount of polyethylene resin produced in the second and subsequent polymerization zones and their properties are determined by determining the amount of resin produced in each stage (can be determined by analysis of unreacted gas). The physical properties of the resin extracted after each stage can be measured and calculated from the additivity of the physical properties.

  Additives, fillers and the like may be added to polyethylene (A) as long as the effects of the present invention are not significantly impaired. 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 60% by weight or more and 90% 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 25 cm or more, preferably 30 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 25 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 0.953 to 1.07 g / cm ³ , preferably 0.960 to 1.05 g / cm ³ . When the density is less than 0.953 g / cm ³ , the rigidity is lowered, and when used for a container and a container lid, the shape is easily deformed. When the density exceeds 1.07 g / cm ³ , the flexibility is lowered, which is not practically preferable.
Here, the density is measured according to JIS-K6922-1,2: 1997.

Characteristic (3) Charpy Impact Value The polyethylene-based molding material of the present invention has a Charpy impact value of 4 KJ / m ² or more, preferably 5 KJ / m ² or more. When the Charpy impact value is less than 4 KJ / m ^2, it tends to break when used for containers, container lids, etc., which is not practically preferable. The Charpy impact value can be adjusted, for example, by increasing or decreasing the amount of component (A), and tends to decrease as the amount of component (A) is decreased.
Here, the Charpy impact value is measured according to JIS-K6922-2.

Characteristic (4) Oxygen permeability The polyethylene-based molding material of the present invention has an oxygen permeability of 100 ml · mm / m ² · day · atm or less, preferably 90 ml · mm / m ² · day · atm or less. . When the oxygen permeability exceeds 100 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 food or the like becomes difficult. In addition, if oxygen permeability is 0.01-100 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 In particular, it is excellent in injection moldability, oxygen permeation prevention properties, and heat 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) Charpy impact value: measured in accordance with JIS-K6922-2.
(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 (MFR) at a temperature of 190 ° C. and a load of 2.16 kg: measured in accordance with JIS-K6922-2: 1997.
(5) Melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg: measured in accordance with JIS-K6922-2: 1997.
(6) Density: Measured according to JIS-K6922-1,2: 1997.
(7) Vicat softening point: Measured according to JIS-K7206.
(8) Flexural modulus: measured in accordance with JIS-K6922-2.
(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.
(10) Hydrocarbon volatiles: 1 g of polyethylene resin was placed in a 25 ml glass sealed container, and the components in the sealed container after heating at 130 ° C. for 60 minutes were analyzed and measured by gas chromatography.
(11) Melt viscosity at a capillary rheometer temperature of 200 ° C. and shear rate of 200 sec ⁻¹ : using a capillary rheometer manufactured by Intesco, using a capillary with a diameter of 1.0 mm and L / D = 20, at a temperature of 200 ° C. and a shear rate The viscosity at a speed of 200 sec ⁻¹ was measured.

2. Resin (1) (A) Component The physical properties of (A1) to (A3), which are the components (A), are shown in Table 1. (A1) and (A2) were produced as follows.
After component (A-1) is polymerized as shown in Table 1 by continuous two-stage polymerization using a Ziegler catalyst and butene-1 as a comonomer, the component (A-2) is polymerized. A polyethylene component (A) was obtained. Each measured value was also shown with those compounding ratios, resin MFR, and HLMFR. The polymerization was performed by supplying ethylene and butene-1 as monomers in the first stage and supplying ethylene in the second stage. The amount (compounding ratio) of the component (A-2) produced in the second stage, its physical properties, etc. are obtained from the unreacted gas analysis after each stage, and the production amount of each stage is obtained. The physical properties of the resin components obtained after and after the second stage were measured and calculated from the additivity.
(A3) was produced by mixing 70% by weight of polyethylene (UJ270 manufactured by Nippon Polyethylene Co., Ltd.) and 30% by weight of commercially available high-pressure radical method low density polyethylene (LJ802 manufactured by Nippon Polyethylene Co., Ltd.) using a commercially available Ziegler catalyst.

(2) Component (B) Commercially available ethylene-vinyl alcohol copolymers having properties shown in Table 2 (Eval G156 (B1) and H101 (B2) manufactured by Kuraray Co., Ltd.) were used.

(3) Component (C) The modified polyethylene obtained in Production Examples 1 and 2 was used. The properties are shown in Table 3.

(Production Example 1)
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 2)
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 1-8)
The components (A) to (C) were blended in the amounts shown in Table 4, and various physical properties were measured. The results are shown in Table 4. As is apparent from Table 4, a product excellent in oxygen permeation prevention properties and excellent mechanical properties such as flexural modulus was obtained, and the container lid suitability such as heat resistance was excellent.

(Comparative Examples 1-5)
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, Comparative Examples 1 and 3 with a small amount of component (B) ethylene-vinyl alcohol are inferior in oxygen permeation-preventing properties, and Comparative Examples 2 and 4 with a small amount of component (A) polyethylene are In Comparative Example 5 in which the Charpy impact strength was inferior and the density of the component (A) polyethylene was small, the flexural modulus was low, 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 heat resistance and does not have mechanical properties such as a decrease in weld strength, it can be used as a container and a container lid, and is industrially very useful.

Claims (7)

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 (MFR) of 0.001 to 100 g / 10 min and a density of 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
Characteristics (1) Spiral flow of t = 2 mm at a molding temperature of 190 ° C. and a mold temperature of 40 ° C. is 25 cm or more. (2) Density is 0.953 to 1.07 g / cm ^3.
Characteristic (3) Charpy impact value is 4 KJ / m ² or more Characteristic (4) Oxygen permeability is 100 ml · mm / m ² · day · atm or less The polyethylene-based molding material according to claim 1, wherein the component (A) is polyethylene that satisfies the following conditions (a-1) to (a-3).
Property (a-1) Flexural modulus is 800 MPa or more Property (a-2) Constant strain ESCR is 1 hour or more Property (a-3) Vicat softening point is 90 ° C. or more The polyethylene-based molding material according to claim 1 or 2, wherein the component (A) is a polyethylene that satisfies the following conditions (a-4) to (a-5).
Characteristic (a-4) Hydrocarbon volatile content is 80 ppm or less Characteristic (a-5) Melt viscosity at a temperature of 200 ° C. and a shear rate of 200 sec ⁻¹ by a capillary rheometer is 500 Pa · sec or less The component (A) is composed of the following components (A-1) and (A-2), the melt flow rate (HLMFR) at a temperature of 190 ° C. and a load of 21.6 kg is 100 to 400 g / 10 minutes, HLMFR / MFR The polyethylene-based molding material according to any one of claims 1 to 3, wherein is from 50 to 200.
Component (A-1) Polyethylene resin having an HLMFR of 0.5 to 10 g / 10 min and a density of 0.935 g / cm ³ or more: 10 to 30 parts by weight Component (A-2) MFR of 30 g / 10 min Above, polyethylene resin having a density of 0.961 g / cm ³ or more: more than 70 parts by weight and 90 parts by weight or less The component (B) is an ethylene-vinyl alcohol copolymer that satisfies the following conditions (b-1) to (b-3): The polyethylene-based molding material described in 1.
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 component according to any one of claims 1 to 5, 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.   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 -6.