JP2019059841A - Polyethylene resin material and hollow molding of the same - Google Patents

Abstract

To provide a polyethylene resin material which has well-balanced rigidity and durability, is excellent in moldability and appearance of a molding, and is particularly excellent in swelling resistance at the time of gasoline immersion, and a material useful as a material of a hollow plastic product such as a container, a bottle, a tank, in particular, a fuel tank of an automobile.SOLUTION: A polyethylene resin material contains one or more two ethylene polymers selected from the group of an ethylene homopolymer and a copolymer of ethylene and α-olefin having 3 to 12 carbon atoms as essential components, and simultaneously satisfies specific characteristics.SELECTED DRAWING: None

Description

The present invention relates to a polyethylene-based resin material and a hollow molded article thereof, more specifically, a polyethylene-based resin material satisfying specific requirements, which is excellent in balance of rigidity and durability, and excellent in moldability and appearance of molded product The present invention relates to a polyethylene-based resin material excellent in swelling resistance when immersed in liquid fuel such as gasoline, and a hollow plastic molded product using the same.
Furthermore, the present invention relates to a polyethylene resin material useful as a material of hollow plastic products such as containers, bottles, tanks, especially fuel tanks of automobiles, and hollow plastic molded articles using the same.

  Hollow plastic moldings used for storage or transport of liquid substances are widely used in daily life and industrial fields, and at present, plastics are used to transport fuel cans such as flammable liquids and harmful substances and plastic bottles etc. It is the most commonly used material in the manufacture of containers. Plastic materials can be reduced in weight because they have a smaller weight / volume ratio than metal materials, and are resistant to corrosion such as rust, and have good impact resistance. It is used as a fuel tank in automobile parts and is replacing conventional metallic materials.

  Hollow molded articles are often obtained by blow molding mainly from polyethylene. In particular, plastic fuel tanks obtained as hollow molded articles are important safety parts for securing the safety of automobiles, and particularly high levels of various performance are required, and materials that sufficiently satisfy these requirements are desirable. It is rare.

  Actually, as commercially available polyethylene used for plastic fuel tanks for automobiles, for example, "HB111R" manufactured by Japan Polyethylene, "4261AG" manufactured by Basell Corporation, etc. are known. Although these are materials that have been evaluated in the market in response to the severe demands of automobile manufacturers, they can not be said to be at sufficiently high levels in terms of lack of rigidity and the like. Under these circumstances, there is a demand for polyethylene materials which are excellent in moldability and impact resistance and in which the balance between rigidity and durability is excellent.

Under such circumstances, attempts have been made to provide a polyethylene resin material with various performance improvements.
Patent Document 1 discloses a polyethylene resin having a multimodal molecular weight distribution, which has a density in the range of about 0.925 g / ccm to about 0.950 g / ccm, and about 0.05 g / l 0 min to about 5 g / c. Disclosed is a polyethylene resin having a melt index (I ₂ ) in the range of 10 minutes and characterized in that it comprises at least one high molecular weight (HMW) ethylene interpolymer and at least one low molecular weight (LMW) ethylene polymer. It is done.
However, the resin described in Patent Document 1 is suitable for use as a pipe resin, and may not necessarily be suitable as a resin for a plastic fuel tank for an automobile.

Patent Document 2, (i) 0.920-0.940g / cm with a ³ density and 0.05-2g / 10 min HLMI, linear manufactured using a first high molecular weight metallocene A low density polyethylene (mLLDPE) resin is prepared and (ii) a density in the range of 0.950-0.970 g / cm ³ and a 5-100 g / 10 min, prepared using a Ziegler Natta or chromium based catalyst A second high density polyethylene (HDPE) having an HLMI of (iii) a broad range or multimodal molecular weight distribution of semi-high molecular weight, physically blending the first and second polyethylene together multi modal comprising the step of allowed to produce polyethylene resins having a HLMI of density and 2 to 20 g / 10 min range 0.948-0.958g / cm ³ Polyethylene resin production process is disclosed having a molecular weight distribution. The resin described in Patent Document 2 has improved environmental stress cracking resistance, impact strength, processability, can reduce wall thickness, and is considered to be particularly advantageous in the automobile industry.
However, the resin described in Patent Document 2 is not necessarily suitable as a resin for a plastic fuel tank for an automobile, in terms of balance between rigidity and durability.

Patent Document 3 (a) has a high load melt index (HLMI) within about 0.2 to about 25 g / 10 min, a density within about 0.91 to about 0.94 g / cc, about 10 At least one olefin having a heterogeneity index (HI) of less than or equal to and about 3 to about 10 carbon atoms per molecule within about 0.01 to about 10 mole percent of comonomers copolymerized A high molecular weight polyethylene containing less than or equal to about 35% by weight produced from a titanium based catalyst system, and (b) a melt index (MI) within about 0.1 to about 5 g / 10 min, about About 65 produced from a chromium based catalyst system having a density within the range of 0.945 to about 0.98 g / cc and a Heterogeneity Index (HI) greater than or equal to about 6 Ethylene polymer compositions are disclosed containing a mixture of polyethylene than the amount% greater or low molecular weight equal to.
However, the composition described in Patent Document 3 is not necessarily suitable as a resin for a plastic fuel tank for an automobile, in terms of balance between rigidity and durability.

Patent Document 4 discloses a composition comprising a high density ethylene polymer and a high molecular weight ethylene polymer, wherein the high density ethylene polymer has a density exceeding the density of the high molecular weight ethylene polymer and the high molecular weight ethylene polymer is high density High density ethylene polymer has a density of 0.94 g / cm ³ to 0.98 g / cm ³ and a molecular weight distribution, Mw / Mn, of more than 8, with a weight average molecular weight that exceeds the weight average molecular weight of the ethylene polymer Disclosed are compositions having a weight average molecular weight of greater than 200,000 g / mole of high molecular weight ethylene polymer and a molecular weight ratio, Mz / Mw, of less than 5.
However, the composition described in Patent Document 4 provides an optimum balance of high top load, low die swell and high ESCR, and it is not always necessary for the automobile plastic fuel tank in terms of balance of rigidity and durability. It can not be said that it is suitable for resin.

Patent Document 5 discloses an ethylene-based resin composition for a hollow molded body characterized by simultaneously satisfying the following requirements [a], [b], [c] and [d].
[A] The melt flow rate (MFR) at a temperature of 190 ° C. under a load of 21.6 kg is in the range of 1.0 to 15 g / 10 min.
[B] The density is in the range of 955 to 970 kg / m ³ .
[C] The number of methyl branches measured by ¹³ C-NMR is less than 0.1 per 1,000 carbon atoms.
[D] The tensile impact strength at −40 ° C. measured according to JIS K7160 is 270 kJ / m ² or more.
The composition described in Patent Document 5 is said to exhibit long-term performance such as high impact resistance and creep resistance while maintaining the rigidity as a molded product even if it is thinned, but the formability, particularly, hollow In terms of moldability, it can not always be said that it is suitable for resins for plastic fuel tanks for automobiles.

Patent Document 6 discloses a polyethylene resin characterized by satisfying the following requirements (1) to (4).
(1): High load melt flow rate (HLMFR) is 1 to 10 g / 10 min.
(2): The density is 0.946 to 0.960 g / cm ³ .
(3): The strain hardening parameter (λmax) of the extension viscosity is 1.05 to 1.50.
(4): The rupture time and the density of the all-round notch type tensile creep test satisfy the following formula (A).
log (breaking time) −-355 x (density) + 337.6 ... Formula (A)
The resin described in Patent Document 6 is considered to be excellent in moldability and durability, and excellent in the balance between impact resistance and rigidity, but the performance is further improved as a resin for plastic fuel tanks for automobiles. Is required.

Patent Document 7 discloses a polyethylene having a weight average molecular weight (Mw) of 30,000 or more at the maximum value of a branching degree distribution curve which is polymerized by a chromium catalyst and shows the molecular weight dependency of short chain branching having 4 or more carbon atoms. Is disclosed.
The resin described in Patent Document 7 is considered to be excellent in moldability, durability, and excellent in balance between impact resistance and rigidity, but the performance is further improved as a resin for plastic fuel tanks for automobiles. Is required.

Patent Document 8 discloses a polyethylene obtained by polymerizing ethylene or ethylene and an α-olefin using a chromium-containing catalyst, and having the following characteristics (1) to (8). There is.
(1): High load melt flow rate (HLMFR) is 1 to 10 g / 10 min.
(2): The density is 0.940 to 0.960 g / cm ³ .
(3): Molecular weight distribution (Mw / Mn) is 25 or more.
(4): The strain hardening parameter (λmax) of the extension viscosity is 1.05 to 1.50.
(5): Charpy impact strength is 7 kJ / m ² or more.
(6): Tensile impact strength is 130 kJ / m ² or more.
(7): The swell ratio (SR) is 50 to 65%.
(8): The rupture time of the all-round notch type tensile creep test is 40 hours or more.
The resin described in Patent Document 8 is considered to be excellent in moldability, durability, and excellent in balance between impact resistance and rigidity, but the performance is further improved as a resin for plastic fuel tanks for automobiles. Is required.

Patent Document 9 discloses a polyethylene-based resin material characterized by satisfying the following requirements (a) to (d).
(A) High load melt flow rate (HLMFR) measured at a load of 21.6 kgf at a temperature of 190 ° C with a density in the range of 0.940 to 0.965 g / cm ³ (4.0 to 10.0 g / h) The swell ratio (HLMFR · SR) measured at a load of 21.6 kgf at a temperature of 190 ° C. for 10 minutes (c) satisfies the following relational expression: HLMFR · SR (%)> 13.2 · ln (HLMFR) +15.5
(D) The material described in Patent Document 9, which has a strain hardening value of 0.35 or less in elongation viscosity measurement, is considered to have both good moldability and excellent physical properties. Further improvement in performance is required as a resin for use.

  Thus, many polyethylene materials having various performance improvements have been proposed, but materials having further improved performance are required.

Japanese Patent Application Publication No. 2005-501951 Japanese Patent Application Publication No. 2005-511868 Unexamined-Japanese-Patent No. 05-194797 Japanese Patent Application Publication No. 2009-506163 WO 2008/087945 WO 2010/150410 International Publication No. 2012/086780 International Publication No. 2012/133713 Unexamined-Japanese-Patent No. 2006-193671

  The present invention has been made in view of the above circumstances, and is excellent in balance of rigidity and durability, excellent in moldability and appearance of molded articles, and excellent in swelling resistance when immersed in liquid fuel such as gasoline. It is an object of the present invention to provide a base resin material and a hollow molded article thereof.

  As a result of intensive studies to solve the above problems, the present inventors can obtain hollow plastic molded articles useful for automotive plastic fuel tanks and the like by using a polyethylene-based resin material having specific polymer physical properties. The present invention has been made.

That is, according to the first aspect of the present invention, one or more ethylenes selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and an α-olefin having 3 to 12 carbon atoms A polyethylene-based resin material is provided, which contains a polymer as an essential component and has the following characteristics [a], [b], [c] and [d].
[A] The melt flow rate (HLMFR) measured at a temperature of 190 ° C. and a load of 21.6 kg is 4 to 10 g / 10 min.
[B] The density is 0.950 to 0.955 g / cm ³ .
[C] Melt tension (MT) measured at 210 ° C. is 120 mN or more.
[D] The rupture time (T) of the all-round notch creep test is at least 60 hours.

According to the second invention of the present invention, in the first invention, the following ethylene-based polymer (A) comprises 30 to 50% by mass and the following ethylene-based polymer (B) 70 to 50% by mass as the essential components. A polyethylene resin material is provided.
Ethylene polymer (A): ethylene polymer having a density of 0.920 to 0.935 g / cm ³ and an HLMFR of 0.01 to 0.5 g / 10 min.
Ethylene-based polymer (B): an ethylene-based polymer having a density of 0.960 to 0.980 g / cm ³ , a melt flow rate (MFR) of 1 to 200 g / 10 min measured at a temperature of 190 ° C. and a load of 2.16 kg Polymer.

  According to a third aspect of the present invention, in the second aspect, the ethylene polymer (A) has a ratio (Mw / Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn). The polyethylene resin material having a molecular weight distribution of 2 to 10 is provided.

According to the fourth invention of the present invention, in the second or third invention, a polyethylene resin material having a molecular weight distribution (Mw / Mn) of 5 to 15 is provided as the ethylene polymer (B). .

  According to the 5th invention of this invention, the hollow molded article which has a layer which consists of a polyethylene resin material of any one invention of the 1st-4th is provided.

  According to the sixth invention of the present invention, the hollow of the fifth invention is at least one selected from the group consisting of a fuel tank, a kerosene can, a drum can, a medicine container, an agrochemical container, a solvent container and a plastic bottle. An article is provided.

  The present invention is excellent in balance of rigidity and durability, excellent in moldability and appearance of molded products, excellent in swelling resistance when immersed in liquid fuel such as gasoline, etc., containers, bottles, tanks, especially fuel tanks for automobiles etc. Further, a polyethylene-based resin material useful as a material of a hollow plastic product of a fuel container can be provided, and furthermore, a hollow molded article using the polyethylene-based resin material can be provided.

It is a graph which shows the relationship between the rupture time (T) (unit: time) and melt tension (MT) (unit: mN) of the full circumference notch type creep test of a polyethylene-based resin material.

  Hereinafter, the polyethylene-based resin material of the present invention and the use thereof and the like will be described in detail for each item. Moreover, "-" which shows a numerical range in this specification is used by the meaning included as a lower limit and an upper limit with the numerical value described before and behind that.

1. Properties of Polyethylene-Based Resin Material The polyethylene-based resin material of the present invention is one or more selected from the group consisting of a homopolymer of ethylene and a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. It is characterized in that it contains an ethylene-based polymer as an essential component and has the following characteristics [a], [b], [c] and [d].
The polyethylene-based resin material of the present invention is excellent in balance of rigidity and durability because it simultaneously satisfies the following characteristics [a], [b], [c] and [d], and is excellent in moldability and appearance of molded articles. It is excellent, and it is excellent also in swelling resistance at the time of liquid fuel immersion, such as gasoline.

Characteristic [a]
The polyethylene resin material of the present invention has a melt flow rate (HLMFR) of 4 to 10 g / 10 min, which is measured at a temperature of 190 ° C. and a load of 21.6 kg, in order to exert the effects of the present invention. The HLMFR is preferably 4.5 to 9.5 g / 10 min, more preferably 5 to 9 g / 10 min.
If the HLMFR is less than 4 g / 10 min, the extrusion amount of the parison in the blow molding is insufficient, the molding becomes unstable, and melt fracture may occur, which is not practical. When HLMFR exceeds 10 g / 10 min, the melt viscosity and melt tension of the parison are insufficient and the formation becomes unstable, which is not practical.
HLMFR can be adjusted at the time of polymerization by methods such as control of polymerization temperature and hydrogen concentration. For example, the HLMFR can be increased by increasing the polymerization temperature or increasing the hydrogen concentration.
Here, HLMFR can be measured under the conditions of a temperature of 190 ° C. and a load of 21.6 kg in accordance with JIS K6922-2: 1997.

Characteristic [b]
The polyethylene resin material of the present invention has a density of 0.950 to 0.955 g / cm ³ from the viewpoint of achieving the effects of the present invention. The density is preferably 0.951~0.954g / cm ^3, further preferably 0.952~0.954g / cm ^3.
If the density is less than 0.950 g / cm ³ , the rigidity of the hollow plastic molded product is insufficient, and the swelling resistance tends to be poor when immersed in liquid fuel such as gasoline, and if it exceeds 0.955 g / cm ³ , the hollow plastic Insufficient durability of molded articles.
The density can be adjusted at the time of polymerization by methods such as control of the type and content of α-olefin. For example, the density is increased by lowering the α-olefin content in polyethylene (reducing the α-olefin addition amount at the time of polymerization) or using the same content, by using an α-olefin having a small carbon number can do.
The density is in accordance with JIS K-7112: 2004, and the pellets are melted by a thermal compression molding machine at a temperature of 160 ° C., and then the temperature is lowered at a rate of 25 ° C./min to form a 2 mm thick sheet. After conditioning in a room at 23 ° C. for 48 hours, it can be placed in a density gradient tube and measured.

Characteristic [c]
The polyethylene-based resin material of the present invention has a melt tension (MT) measured at 210 ° C. of 120 mN or more from the viewpoint of achieving the effects of the present invention. The melt tension (MT) is preferably 125 mN or more, more preferably 128 mN or more.
If the melt tension (MT) is less than 120 mN, the drawdown at the time of molding tends to be large and it becomes difficult to mold.
For melt tension (MT), using Capillograph manufactured by Toyo Seiki Seisakusho, nozzle diameter 2.095 mmφ, nozzle length 8.00 mm, inflow angle 180 °, setting temperature 210 ° C., piston extrusion speed 10.0 mm / min, pulling It can be measured at a speed of 4.0 m / min.
The melt tension (MT) can be adjusted by the molecular weight and molecular weight distribution of polyethylene, and can usually be increased by increasing the molecular weight and can be increased by broadening the molecular weight distribution.

Characteristic [d]
The polyethylene resin material of the present invention has a breaking time (T) (unit: hour) of 60 hours or more in the all-around notch creep test from the viewpoint of achieving the effects of the present invention. It is preferable that the breaking time (T) of the said full circumference notch type creep test is 70 hours or more. The longer the total notch creep test (FNCT), the better the long-term durability, such as environmental stress cracking resistance.
The fracture time by the full notch tensile creep test can be measured by the following method. That is, after compression molding of a sheet having a thickness of 5.9 mm in accordance with JIS K-6992-2 (2004 edition), the classification shown in JIS K-6774 (2004 edition) Annex 5 (definition) FIG. 1 Test pieces of the shape and dimensions of "Nominal 50" are prepared and subjected to full notch tensile creep test (FNCT) in pure water at 80 ° C. The tensile load is 88N, 98N and 108N, and the number of test points is 2 for each load. The fracture time at a nominal stress of 6 MPa is used as an indicator of creep resistance by the least squares method from the obtained six-point plot of rupture time and nominal stress in a double logarithmic scale.

  The polyethylene resin material of the present invention preferably has at least one of the following characteristics [e] to [j] in addition to the characteristics [a], [b], [c] and [d].

Characteristic [e]
The polyethylene-based resin material of the present invention satisfies the relationship represented by the following formula (1) with the rupture time (T) (unit: hour) and the melt tension (MT) (unit: mN) in the all-round notch creep test. (Refer to FIG. 1). FIG. 1 is a graph showing the relationship between the rupture time (T) (unit: hour) and the melt tension (MT) (unit: mN) of the all-around notch creep test of the polyethylene resin material. is there).
The polyethylene-based resin material satisfying the following formula (1) means that it is a polyethylene-based resin material capable of showing a relatively large breaking time even if the melt tension is increased, and the moldability and the durability It is an index showing that it is excellent in balance.
T ¹⁵ 1530 x e ^{(-0.025 MT)} formula (1)
Here, e is the Napier number (the base of natural logarithms).

Characteristic [f]
The polyethylene-based resin material of the present invention preferably has a flexural modulus of 1,100 to 1,700 MPa measured according to JIS K7171, more preferably 1,100 to 1,600 MPa, 1 , 100 to 1,400 MPa is more preferable, and 1,100 to 1,300 MPa is still more preferable.
When the flexural modulus is in the above range, the resulting hollow molded article is excellent in rigidity particularly at room temperature. That is, since it is hard and strong, it becomes possible to make a molded article thinner than before.

Characteristic [g]
Since the polyethylene resin material of the present invention has the above-mentioned properties [a], [b], [c] and [d], the swelling ratio to fuel is small.
The polyethylene resin material of the present invention uses, for example, a test piece having a length of 80.0 mm, a width of 10.0 mm, and a thickness of 4.0 mm, and a fuel of Fuel C (isooctane / toluene = 50/50% by volume) The sample was immersed at 60 ° C for 168 hours, the weight change before and after immersion was measured, and the weight change rate based on the weight before immersion was determined. ) / Weight before immersion × 100}, that is, the swelling ratio is preferably 10% or less, more preferably 9.6% or less. When the swelling ratio is 10% or less, preferably 9.6% or less, the fuel tank suitability is excellent.

Characteristic [h]
The polyethylene resin material of the present invention uses, for example, a test piece having a length of 80.0 mm, a width of 10.0 mm, and a thickness of 4.0 mm, and a fuel of Fuel C (isooctane / toluene = 50/50% by volume) At 60 ° C for 168 hours, measure the dimensional change before and after immersion, and measure the dimensional change rate based on the dimensions before immersion {(dimension after immersion-dimension before immersion) / dimension before immersion × 100} When determined, the dimensional change rate is preferably 4.0% or less, more preferably 3.8% or less. Those having such a dimensional change rate are excellent in fuel tank suitability. The dimensional change rate is the average value of the values obtained by the formula {(dimension after immersion−dimension before immersion) / (dimension before immersion) × 100} for each of the length, width, and thickness. It is.
The polyethylene resin material of the present invention has the above-mentioned characteristics [a], [b], [c] and [d], so the dimensional change ratio to fuel is small.

Characteristic [i]
The polyethylene resin material of the present invention preferably has a flexural modulus of 300 MPa or more, preferably 350 MPa or more, and 370 MPa or more, which is measured according to JIS K7171 of the test piece after fuel immersion. Is more preferred.
When the flexural modulus of the test piece after fuel immersion is in the above range, the resulting hollow molded article is excellent in fuel oil resistance.
Flexural modulus after fuel immersion, test piece for flexural modulus measurement is immersed in fuel (Isooctane / toluene = 50/50% by volume) of Fuel C at 60 ° C for 168 hours, and flexural elastic modulus test after fuel immersion The flexural modulus of elasticity of the piece can be measured in accordance with JIS K7171: 2008.

Characteristic [j]
It is preferable that the polyethylene resin material of the present invention does not generate melt fracture and has good moldability.
Melt fracture can be measured according to JIS K 7919: 1999 (ISO 11443: 1995). For example, using CAPIROGRAPH 1B manufactured by Toyo Seiki Seisakusho, the melt fracture is measured at a nozzle diameter of 1.0 mmφ, a nozzle length of 40 mm, an inflow angle of 90 °, and a setting temperature of 210 ° C. under a piston extrusion speed of 20.0 mm / min. It is possible to confirm the occurrence of

2. Structure and Production Method of Polyethylene-Based Resin Material The polyethylene-based resin material of the present invention is one or two selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and an α-olefin having 3 to 12 carbon atoms. The above characteristics [a] to [d] are simultaneously satisfied by using ethylene polymer of a kind or more as an essential component. The polyethylene-based resin material of the present invention may further contain optional components described later in addition to the ethylene-based polymer, as long as the characteristics [a] to [d] are simultaneously satisfied.
The copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms of the present invention contains 0 to 40 mol%, preferably 0 to 30 mol%, of constituent units derived from an α-olefin having 3 to 12 carbon atoms, It is an ethylene polymer containing 2.0 mol% or less, preferably 0.02 to 1.5 mol%, more preferably 0.02 to 1.3 mol%.
Here, as the α-olefin having 3 to 12 carbon atoms (hereinafter, also simply referred to as “α-olefin”), propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3 -Methyl-1-pentene, 1-octene, 1-decene and the like. In the present invention, it is preferable to use at least one selected from 1-hexene, 4-methyl-1-pentene, and 1-octene among these α-olefins.

The polyethylene-based resin material of the present invention is not particularly limited as to the polymerization catalyst, the production method, etc., as long as the above-mentioned characteristics [a] to [d] are simultaneously satisfied.
Among them, the polyethylene-based resin material of the present invention contains 30 to 50% by mass of the following ethylene-based polymer (A) and 70 to 50% by mass of the following ethylene-based polymer (B) as the essential components. It is preferable from the point of being easy to satisfy a]-[d] simultaneously, and also being easy to satisfy the said characteristic [e].
Ethylene polymer (A): ethylene polymer having a density of 0.920 to 0.935 g / cm ³ and an HLMFR of 0.01 to 0.5 g / 10 min.
Ethylene-based polymer (B): an ethylene-based polymer having a density of 0.960 to 0.980 g / cm ³ , a melt flow rate (MFR) of 1 to 200 g / 10 min measured at a temperature of 190 ° C. and a load of 2.16 kg Polymer.

  In the polyethylene-based resin material of the present invention, the composition ratio of the ethylene-based polymer (A) to the ethylene-based polymer (B) is ethylene-based polymer (B) relative to 30 to 50% by mass of ethylene-based polymer (A). 70 to 50% by mass is preferable, and the ethylene-based polymer (B) 69 to 51% by mass is more preferable with respect to 31 to 49% by mass of the ethylene-based polymer (A), and ethylene-based polymer (A) 32 to 48 It is still more preferable that the ethylene-based polymer (B) is 68 to 52% by mass with respect to the mass%. If the composition ratio of this ethylene-based polymer (A) is less than 30% by mass, in the final resin composition, HLMFR can not achieve within the specified range, and the moldability is deteriorated due to the decrease of the melt tension, There is a possibility that environmental stress crack resistance may be reduced. On the other hand, if the composition ratio of the ethylene-based polymer (A) exceeds 50% by mass, the HLMFR and density of the polyethylene-based resin material of the present invention decrease, the flowability and rigidity may decrease, and rigidity and environmental stress There is a possibility that the polymer may be reduced in the balance of cracking.

(1) Ethylene-based polymer (A)
The ethylene-based polymer (A) is an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. The manufacturing method of an ethylene homopolymer or the copolymer of ethylene and a C3-C12 alpha olefin is mentioned later.
The ethylene polymer (A) has a density of 0.920 to 0.935 g / cm ³ , preferably 0.921 to 0.934 g / cm ³ , and more preferably 0.922 to 0.934 g / cm ^3. cm ³ The density can be measured in the same manner as the density of the property [b] described above.
If the density of the ethylene-based polymer (A) is less than 0.920 g / cm ³ , the rigidity of the molded product may be insufficient. If it exceeds 0.935 g / cm ³ , the durability may be insufficient. There is a risk of
Adjustment of the density can be performed, for example, by changing the amount of α-olefin to be copolymerized with ethylene, and can be decreased by increasing the amount of α-olefin.

The ethylene polymer (A) has an HLMFR of 0.01 to 0.5 g / 10 min, preferably 0.02 to 0.5 g / 10 min, and more preferably 0.03 to 0.5 g / m. 10 minutes. HLMFR can be measured in the same manner as the HLMFR of the above-mentioned property [a].
If the HLMFR of the ethylene-based polymer (A) is less than 0.01 g / 10 min, the flowability at the time of molding may be insufficient, the molding may become unstable, and it may not be practical. If the amount is exceeded, impact resistance tends to decrease.
Adjustment of HLMFR can be adjusted by changing the amount of chain transfer agent (such as hydrogen) coexisting in ethylene polymerization, or changing the polymerization temperature to increase the amount of hydrogen or increase the polymerization temperature By doing this, you can make it bigger.

The ethylene-based polymer (A) has a molecular weight distribution represented by the ratio (Mw / Mn) of weight-average molecular weight (Mw) to number-average molecular weight (Mn) measured by gel permeation chromatography (GPC) method. It is preferable that it is 2-10. If the molecular weight distribution (Mw / Mn) of the ethylene-based polymer (A) exceeds 10, the mechanical strength may be reduced.
Mw / Mn of the ethylene-based polymer (A) is preferably 2.0 or more, for example 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, preferably 10 or less, for example 9 .0 or less, 8.0 or less, or 7.0 or less. Mw / Mn of the ethylene-based polymer (A) can be limited by any of the above lower limits and any of the upper limits. For example, it is 2.0-10, 2.0-9.0, 3.0-8.0, 3.5-8.0, 3.5-7.0, 4.0-7.0 etc. .
The molecular weight distribution (Mw / Mn) can be in a predetermined range mainly by selecting the polymerization catalyst and the polymerization conditions, and can be in a predetermined range by mixing a plurality of components having different molecular weights. be able to.
The molecular weight distribution (Mw / Mn) of the ethylene-based polymer (A) can be adjusted mainly by the type of polymerization catalyst used for the polymerization reaction of the ethylene-based polymer (A), preferably a Ziegler catalyst is mentioned .

The measurement of GPC can be performed by the following method.
Apparatus: Alliance GPC V2000 type manufactured by WATERS, Inc. Column: Two HT-806M manufactured by Showa Denko + 1 HT-G Measurement temperature: 145 ° C.
Concentration: 1 mg / 1 ml
Solvent: o-dichlorobenzene In addition, calculation of molecular weight and calibration of a column can be performed based on the following method.
GPC chromatography data is read into a computer at a frequency of 1 point / second, data processing is performed as described in “Size Exclusion Chromatography”, published by Mori Sadao, Kyoritsu Publishing Co., and Mw and Mn values are calculated. Can. The conversion from the measured retention volume to the molecular weight is performed using a calibration curve with standard polystyrene prepared in advance.

The ethylene-based polymer (A) is not particularly limited as far as the polymerization catalyst, the production method, and the like, as long as the above-described requirements are satisfied.
Phillips-type catalysts cause long-chain branching in molecular structure and generally have good swell ratio and drawdown resistance in blow moldability, but generally have poor environmental stress crack resistance (ESCR) that exhibits long-term durability as durability. Therefore, a Ziegler-based catalyst that does not cause long-chain branching in the molecular structure is preferably used in order to improve the ESCR as durability as well as the swell ratio in blow moldability and the drawdown resistance.
The Ziegler-based catalyst is preferably produced using a transition metal catalyst composed of a solid Ziegler catalyst containing at least titanium and magnesium and an organoaluminum compound.

The solid Ziegler catalysts containing titanium and magnesium used in the present invention are well known, for example, JP-A-53-78287, JP-A-54-21483, JP-A-55-71707, The catalyst system described in each publication such as JP-A-58-225105 is used.
Specifically, a solid catalyst component obtained by contacting a tetravalent titanium compound with a co-ground product obtained by co-grinding aluminum trihalide, an organosilicon compound having a Si-O bond and magnesium alcoholate And catalyst systems comprising an organoaluminum compound.

The solid catalyst component preferably contains 1 to 15% by mass of a titanium atom. The organic silicon compound is preferably one having a phenyl group or an aralkyl group, such as diphenyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, triphenylethoxysilane, triphenylmethoxysilane and the like.
The ratio of aluminum trihalide and organosilicon compound used per mole of magnesium alcoholate is generally 0.02 to 1.0 mole, and preferably 0.05 to 0.20 mole, in producing the co-ground product. Mol is preferred. The ratio of aluminum atom of trihalogenated aluminum to silicon atom of organic silicon compound is preferably 0.5 to 2.0 molar ratio.
In order to produce a co-ground product, a method which is usually carried out using a pulverizer such as a rotary ball mill, an oscillating ball mill and a colloid mill which are generally used in producing a solid catalyst component of this kind is applied. do it. The average particle size of the resulting co-ground product is usually 50 to 200 μm, and the specific surface area is 20 to ²⁰⁰ m ² / g.
A solid catalyst component can be obtained by contacting the co-ground product obtained as described above with a tetravalent titanium compound in a liquid phase.
The organoaluminum compound used in combination with the solid catalyst component is preferably a trialkylaluminum compound, and examples thereof include triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, tri-i-butylaluminum and the like.

  The ethylene polymer (A) is a homopolymer of ethylene or ethylene and an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene And 1-octene and the like. Copolymerization with dienes is also possible for the purpose of modification. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like. In addition, although the comonomer content in the case of superposition | polymerization can be selected arbitrarily, For example, in the case of the copolymerization of ethylene and a C3-C12 alpha-olefin, ethylene-alpha-olefin copolymer The α-olefin content in it is 0 to 40 mol%, preferably 0 to 30 mol%, and usually 2.0 mol% or less, preferably 0.02 to 1.5 mol%, more preferably 0.02 to 1. It is 3 mol%.

Although the molecular weight of the formed polymer can be adjusted to some extent by changing the polymerization conditions such as the polymerization temperature and the molar ratio of the catalyst, the molecular weight can be controlled more effectively by adding hydrogen to the polymerization reaction system. Can.
Moreover, even if it adds the component for the purpose of water removal in the polymerization system, a so-called scavenger, it can be implemented without any problem.
Such scavengers include organic aluminum compounds such as trimethylaluminum, triethylaluminum and triisobutylaluminum, the aforementioned organic aluminum oxy compounds, modified organic aluminum compounds containing branched alkyl, organic zinc compounds such as diethyl zinc and dibutyl zinc, diethyl Organic magnesium compounds such as magnesium, dibutyl magnesium and ethylbutyl magnesium, and Grignard compounds such as ethyl magnesium chloride and butyl magnesium chloride are used. Among these, triethylaluminum, triisobutylaluminum and ethylbutylmagnesium are preferable, and triethylaluminum is particularly preferable.
The present invention can be applied to a multistage polymerization system of two or more stages having different polymerization conditions such as hydrogen concentration, amount of monomers, polymerization pressure, polymerization temperature and the like without any problem.

  The ethylene-based polymer (A) can be produced by a production process such as a gas phase polymerization method, a solution polymerization method or a slurry polymerization method, preferably a slurry polymerization method. Among the polymerization conditions of the ethylene-based polymer (A), the polymerization temperature can be selected from the range of 0 to 200 ° C. In slurry polymerization, the polymerization is carried out at a temperature lower than the melting point of the produced polymer. The polymerization pressure can be selected from the range of atmospheric pressure to about 10 MPa. From aliphatic hydrocarbons such as hexane, heptane and isobutane, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane in a state that oxygen, water and the like are substantially cut off It can be prepared by slurry polymerization of ethylene and alpha-olefins in the presence of an inert hydrocarbon solvent of choice.

  The ethylene-based polymer (A) can be continuously polymerized in a single polymerization vessel, a plurality of reactors connected in series or in parallel, and a plurality of ethylene-based polymers, as long as the range specified in the present invention is satisfied. It may be mixed after being separately polymerized.

(2) Ethylene-based polymer (B)
The ethylene-based polymer (B) is an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. The manufacturing method of an ethylene homopolymer or the copolymer of ethylene and a C3-C12 alpha olefin is mentioned later.
The ethylene polymer (B) has a density of 0.960 to 0.980 g / cm ³ , preferably 0.961 to 0.979 g / cm ³ , and more preferably 0.962 to 0.978 g / cm ^3. cm ³ The density can be measured in the same manner as the density of the property [b] described above.
If the density of the ethylene-based polymer (B) is less than 0.960 g / cm ³ , the rigidity of the molded article may become apparent, while if it exceeds 0.980 g / cm ³ , the impact resistance may be increased. There is a risk of shortage.
Adjustment of the density can be performed, for example, by changing the amount of α-olefin to be copolymerized with ethylene, and can be decreased by increasing the amount of α-olefin.

The ethylene polymer (B) has a melt flow rate (MFR) of 1 to 200 g / 10 min, preferably 2 to 195 g / 10 min, measured at a temperature of 190 ° C. and a load of 2.16 kg, and more preferably Is 5 to 190 g / 10 min. MFR can be measured in the same manner as the HLMFR of the above-mentioned property [a].
If the MFR of the ethylene-based polymer (B) is less than 1 g / 10 min, the fluidity may be insufficient at the time of molding, and the molding may become unstable and it may not be practical, and the MFR exceeds 200 g / 10 min. , Impact resistance tends to decrease.
Adjustment of MFR can be adjusted by changing the amount of chain transfer agent (such as hydrogen) coexisting in ethylene polymerization, or changing the polymerization temperature to increase the amount of hydrogen or increase the polymerization temperature. By doing this, you can make it bigger.

The ethylene-based polymer (B) has a molecular weight distribution represented by the ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) measured by gel permeation chromatography (GPC) method. It is preferable that it is 5-15. When the molecular weight distribution (Mw / Mn) exceeds 15, the mechanical strength tends to decrease.
Mw / Mn of the ethylene-based polymer (B) is preferably 5.0 or more, for example 5.5 or more, 6.0 or more, preferably 15 or less, for example 14 or less, 13 or less, 12 or less, 11 or less , 10 or less. Mw / Mn of the ethylene-based polymer (B) can be limited by any of the above lower limits and any of the upper limits. For example, it is 5.0-15, 5.5-14, 6.0-13, 5.0-12, 5.5-11, 5.5-13 grade | etc.,.
The molecular weight distribution (Mw / Mn) of the ethylene-based polymer (B) can be adjusted mainly by the type of polymerization catalyst used for the polymerization reaction of the ethylene-based polymer (B), preferably a Ziegler catalyst is mentioned .

The ethylene-based polymer (B) is not particularly limited as far as the polymerization catalyst, the production method, etc., as long as the above-mentioned requirements are satisfied.
Phillips-type catalysts cause long-chain branching in molecular structure and generally have good swell ratio and drawdown resistance in blow moldability, but generally have poor environmental stress crack resistance (ESCR) that exhibits long-term durability as durability. Therefore, a Ziegler-based catalyst that does not cause long-chain branching in the molecular structure is preferably used in order to improve the ESCR as durability as well as the swell ratio in blow moldability and the drawdown resistance.
The Ziegler-based catalyst is preferably produced using a transition metal catalyst composed of a solid Ziegler catalyst containing at least titanium and magnesium and an organoaluminum compound.

  As the Ziegler-based catalyst used for producing the ethylene-based polymer (B), the same Ziegler-based catalyst as described for the ethylene-based polymer (A) can be used.

  The ethylene polymer (B) is a homopolymer of ethylene or ethylene and an α-olefin having 3 to 12 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene And 1-octene and the like. Copolymerization with dienes is also possible for the purpose of modification. Examples of the diene compound used at this time include butadiene, 1,4-hexadiene, ethylidene norbornene, dicyclopentadiene and the like. In addition, although the comonomer content in the case of superposition | polymerization can be selected arbitrarily, For example, in the case of the copolymerization of ethylene and a C3-C12 alpha-olefin, ethylene-alpha-olefin copolymer The α-olefin content in it is 0 to 40 mol%, preferably 0 to 30 mol%, and usually 2.0 mol% or less, preferably 0.02 to 1.5 mol%, more preferably 0.02 to 1. It is 3 mol%.

Although the molecular weight of the formed polymer can be adjusted to some extent by changing the polymerization conditions such as the polymerization temperature and the molar ratio of the catalyst, the molecular weight can be controlled more effectively by adding hydrogen to the polymerization reaction system. Can.
Moreover, even if it adds the component for the purpose of water removal in the polymerization system, a so-called scavenger, it can be implemented without any problem. As the said scavenger, the thing similar to the scavenger demonstrated by the said ethylene-based polymer (A) can be used.

  The ethylene-based polymer (B) can be produced by a production process such as a gas phase polymerization method, a solution polymerization method or a slurry polymerization method, preferably a slurry polymerization method. Among the polymerization conditions of the polyethylene component (B), the polymerization temperature can be selected from the range of 0 to 200 ° C. In slurry polymerization, the polymerization is carried out at a temperature lower than the melting point of the produced polymer. The polymerization pressure can be selected from the range of atmospheric pressure to about 10 MPa. From aliphatic hydrocarbons such as hexane, heptane and isobutane, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane in a state that oxygen, water and the like are substantially cut off It can be prepared by slurry polymerization of ethylene and alpha-olefins in the presence of an inert hydrocarbon solvent of choice.

  The ethylene-based polymer (B) may be continuously polymerized in a single polymerization vessel, a plurality of reactors connected in series or in parallel, and a plurality of ethylene-based polymers, as long as the range specified in the present invention is satisfied. It may be mixed after being separately polymerized.

The polyethylene-based resin material of the present invention may be one obtained by multistage polymerization of the ethylene-based polymer (A) and the ethylene-based polymer (B), or may be a blended composition.
In a polymerization apparatus in which two or more reactors are connected in series using the above catalyst, the ethylene-based polymer (A) is preferably used in the first-stage reactor as the second-stage polymerization process. A method of continuously polymerizing the ethylene-based polymer (B) in a reactor, or the ethylene-based polymer (B) in a reactor at the former stage, and the ethylene-based polymer (A) in a reactor at the latter stage Be
As a method of blending the ethylene polymer (A) and the ethylene polymer (B), a method of increasing the degree of kneading is preferable. For example, a twin screw extruder, a single screw extruder, a Banbury mixer, continuous kneading Blending methods by machine, bravender, lower bra bender etc. may be mentioned.

(3) Other Additives The polyethylene-based resin material of the present invention, in addition to the ethylene-based polymer (A) and the ethylene-based polymer (B), within the range simultaneously satisfying the characteristics [a] to [d] The following substances can be blended as optional components.
For example, various ethylene polymers such as high density polyethylene, low density polyethylene, high pressure polyethylene, polar monomer graft modified polyethylene, ethylene wax, ultrahigh molecular weight polyethylene, ethylene elastomer, and modified products thereof can be used. The addition of high density polyethylene is preferred to improve the rigidity, heat resistance, impact strength and the like. The addition of low density polyethylene is preferred to improve the flexibility, impact strength, easy adhesion, transparency, low temperature strength and the like.
The addition of high-pressure polyethylene is preferable for improving the flexibility, easy adhesion, transparency, low temperature strength, moldability and the like. Addition of polar monomer graft modified polyethylene such as maleic acid modified polyethylene, ethylene / acrylic acid derivative copolymer, ethylene / vinyl acetate copolymer, etc., flexibility, easy adhesion, colorability, compatibility with various materials, gas barrier property, etc. To improve the The addition of an ethylene-based wax is preferable in order to improve colorability, compatibility with various materials, molding processability and the like. The addition of ultrahigh molecular weight polyethylene is preferred to improve mechanical strength, abrasion resistance and the like. The addition of an ethylene-based elastomer is preferable in order to improve the flexibility, mechanical strength, impact strength and the like.
In addition to the above polymers, various resins can be used. Specifically, various nylon resins, various polyamides, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), various polyesters, polycarbonate resins, EVOH, EVA, PMMA, PMA, various engineering plastics, polylactic acid, celluloses, etc. Natural rubbers, polyurethane, polyvinyl chloride, fluorine-based resin such as Teflon (registered trademark), inorganic polymer such as silicon resin, and the like.

The polyethylene-based resin material of the present invention can be pelletized by mechanical melt mixing with a pelletizer, homogenizer or the like according to a conventional method, and then molded by various molding machines to obtain a desired molded article.
In addition to ethylene-based polymers obtained by the above method, in addition to other olefin-based polymers and rubbers, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, Known additives such as a clouding agent, an antiblocking agent, a processing aid, a color pigment, a crosslinking agent, a foaming agent, an inorganic or organic filler, a flame retardant and the like can be blended.
As the additive, for example, one or two or more kinds of antioxidants (phenol based, phosphorus based, sulfur based), lubricants, antistatic agents, light stabilizers, ultraviolet absorbers and the like can be used in combination as appropriate. As the filler, calcium carbonate, talc, metal powder (aluminum, copper, iron, lead, etc.), silica, diatomaceous earth, alumina, gypsum, mica, clay, asbestos, graphite, carbon black, titanium oxide, etc. can be used. Among them, calcium carbonate, talc and mica are preferably used. In any case, various additives may be added to the above-mentioned polyethylene, if necessary, and the resulting mixture may be kneaded using a kneading extruder, Banbury mixer or the like to form a molding material.

  As an antioxidant, for example, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, 2,6-di-t -Butyl-4-ethylphenol, 2,4,6-tri-t-butylphenol, 2,5-di-t-butylhydroquinone, butylated hydroxyanisole, n-octadecyl-3- (3 ', 5'-di) Monophenols such as -t-butyl-4'-hydroxyphenyl) propionate and stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 4,4'-dihydroxydiphenyl, 2, 2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'- Tylene bis (2,6-di-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,6-bis (2′-hydroxy-3′-tert-butyl-5 Bisphenols such as' -methylbenzyl) -4-methylphenol, 1,1,3-tris (2'-methyl-4'-hydroxy-5'-t-butylphenyl) butane, 1,3,5-trimethyl 2,4,6-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) benzene, tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate, tris [Β- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-) [Droxyphenyl) propionate] tri- or higher polyphenols such as methane, etc., 2,2'-thiobis (4-methyl-6-t-butylphenol), 4,4'-thiobis (2-methyl-6-t-butylphenol) And thiobisphenols such as 4,4'-thiobis (3-methyl-6-t-butylphenol), aldol-α-naphthylamine, naphthylamines such as phenyl-α-naphthylamine and phenyl-β-naphthylamine, p-isopropoxy Diphenylamines such as diphenylamine, N, N'-diphenyl-p-phenylenediamine, N, N'-di-β-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N- Fe such as isopropyl-N'-phenyl-p-phenylenediamine And the like. Among these, monophenols, bisphenols, polyphenols of tri or higher, thiobisphenols and the like are preferable.

  Specific examples of light stabilizers and ultraviolet light absorbers include 4-t-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, ethyl 2-cyano-3,3 ' -Diphenyl acrylate, 2-ethylhexyl 2-diano-3,3'-diphenyl acrylate, 2 (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2 '-Hydroxy-3,5'-di-t-butylphenyl) benzotriazole, 2 (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-5-chlorobenzophenone, 2-hydroxy-4- Methoxybenzophenone-2-hydroxy-4-octoxybenzophenone, 2 (2'-hydro) Shi-4-octoxyphenyl) benzotriazole, monoglycol salicylate, Okizarikku acid amide, phenyl salicylate, 2,2 ', 4,4'-like tetrahydroxy benzophenone.

Examples of the metal damage inhibitor include hydrazide derivatives, oxalic acid derivatives and salicylic acid derivatives.
Hydrazide derivatives As metal damage inhibitors, N, N'-diacetyl adipate hydrazide, adipate bis (α-phenoxypropionyl hydrazide), terephthalic acid bis (α-phenoxypropionyl hydrazide), sebacic acid bis (α-phenoxypropionyl hydrazide) And isophthalic acid bis (β-phenoxypropionyl hydrazide) etc., and examples of oxalic acid derivative metal damage inhibitors include N, N′-dibenzal (oxalyl dihydrazide), N-benzal- (oxalyl dihydrazide), oxalyl bis -4-methylbenzylidene hydrazide, oxalyl bis-3-ethoxybenzylidene hydrazide and the like, and as a salicylic acid derivative metal damage inhibitor, 3- (N-salicyloyl) amino-1,2,4-triazole, deca It includes Ji dicarboxylic acid disalicyloylhydrazide.
In the present invention, a preferred metal damage inhibitor is a salicylic acid derivative metal damage inhibitor.

The addition amount of the stabilizer such as the antioxidant, the light stabilizer, the ultraviolet light absorber, and the metal damage inhibitor is not particularly limited, but preferably 0.001 relative to 100 parts by mass of the ethylene-based polymer. And 5 parts by mass, and more preferably 0.001 to 3 parts by mass. If the amount is less than 0.001 part by mass, a sufficient stabilization effect can not be obtained, and if it exceeds 5 parts by mass, effects such as coloring occur, and molding defects tend to occur, and an effect corresponding to an increase in the addition amount is obtained. It is not economical and is not.
The stabilizer in the ethylene-based polymer can be measured using fluorescent X-ray analysis, gas chromatography, or liquid chromatography.

3. Molding of Polyethylene-Based Resin Material The polyethylene-based resin material of the present invention is excellent in balance of rigidity and durability, and excellent in moldability, so that various molded articles can be produced by various molding methods. Since it is excellent in drawdown resistance, it is preferably molded mainly by a hollow molding method etc., and various molded articles such as a hollow container can be suitably obtained.
The hollow molded article of the polyethylene-based resin material of the present invention is not particularly limited, but can be produced by an extrusion blow molding method using a conventionally known multilayer hollow molding machine. For example, after heating and melting the constituent resin of each layer with a plurality of extruders, a multi-layer hollow plastic is extruded by extruding a molten parison with a multi-layer die, and then the parison is sandwiched between molds and air is blown into the parison. An article is manufactured.

In addition, the polyethylene resin material of the present invention is excellent in balance of rigidity and durability, and excellent in moldability and appearance of a molded product. Therefore, as products, tanks such as a fuel tank, kerosene cans, drums, containers for medicine, It is provided as products such as containers for pesticides, containers for solvents, various plastic bottles. Other applications include various pipes for gas and water supply, films, laminates, coatings, fibers, injection molded articles for food and household sundries, etc., compression injection molded articles, rotational molded articles or extrusion molded articles, etc. It can be mentioned.
The polyethylene resin material obtained by the present invention is characterized by wide molecular weight distribution and is excellent in compatibility with other ethylene polymers, and not only as a single material, but also with other polyethylene for tension improvement. It can also be used as a blend material of the above-mentioned product use.
The polyethylene-based resin material of the present invention satisfies the above-mentioned characteristics, so a molded article using the same is excellent in environmental stress crack resistance and impact resistance, is thin and lightweight, and is also rigid and heat resistant. In addition to being excellent, the compatibility of the resin component is high, the surface properties of the molded article are excellent, and the appearance is particularly good. Further, it can be molded thinner, lighter, faster in crystallization speed, excellent in high-speed formability, capable of forming high-cycle forming, and excellent in pinch-off characteristics.
Thus, it is suitable for applications such as containers requiring such properties. For example, it can be suitably used for applications such as automobile fuel tanks, other cosmetic containers, containers for detergents, shampoos and rinses, and containers for food such as edible oils.
Above all, since it is excellent in the balance between moldability and durability, and excellent in swelling resistance when immersed in liquid fuel such as gasoline, it is preferably used for applications such as fuel containers, particularly, automotive fuel tanks, among others. it can.

4. Hollow molded article The hollow molded article of the present invention has a structure having at least one layer, preferably a multilayer, having at least one layer of the polyethylene resin material of the present invention. Further, the hollow molded article of the present invention may have a single layer structure made of the polyethylene resin material of the present invention. When the hollow molded article has a multilayer structure, it is preferable to have a permeation reducing barrier layer, and a barrier layer is usually used for the permeation reducing barrier layer.

When the layer structure of the hollow molded article (hollow plastic molded article) of the present invention is two or more layers, the innermost layer and the outermost layer are preferably made of the polyethylene resin material of the present invention.
The hollow molded article is preferably a multilayer structure comprising a permeation reducing barrier layer in which at least one barrier layer is present to reduce the penetration of volatile substances and the barrier layer is composed of a polar barrier polymer. For example, in the case of a plastic fuel tank, when the wall of the tank has a multi-layered structure, the barrier layer (it alone does not have sufficient moldability and mechanical strength) can be immobilized between the two layers of polyethylene of the present invention There is an advantage. As a result, particularly during coextrusion blow molding, the formability of the material having two or more layers of the polyethylene resin material of the present invention is improved mainly due to the improved formability of the polyethylene resin material of the present invention Ru. Furthermore, the improved performance of the inventive polyethylene-based resin material has a very important influence on the mechanical strength of the material, which makes it possible to significantly increase the strength of the inventive hollow molded article.
In the case of a hollow molded article, the base layer may be coated on the surface of the polyethylene resin layer of the present invention by treatment such as fluorination, surface coating or plasma polymerization.

  The hollow molded article is preferably a hollow molded article of 4 types and 6 layers in which the innermost layer, the adhesive layer, the barrier layer, the adhesive layer, the recycled material layer, and the outermost layer are laminated in this order from the inside. By sandwiching the barrier layer with the adhesive layer, high barrier properties are exhibited. By having the recycled material layer between the outermost layer and the adhesive layer, effects of cost reduction due to reduction of raw material cost and retention of rigidity of the hollow molded article are exhibited.

  Hereinafter, the constitution of each layer and the layer constitution ratio in the above performance will be described in detail.

(1) Outermost Layer The resin constituting the outermost layer of the hollow molded article is preferably the polyethylene-based resin material of the present invention.

(2) Innermost Layer The resin constituting the innermost layer of the hollow molded article is preferably the polyethylene-based resin material of the present invention, and may be the same as or different from the resin constituting the outermost layer described above It may be

(3) Barrier Layer The resin forming the barrier layer of the hollow molded product is selected from ethylene vinyl alcohol resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, etc., and in particular, it is composed of ethylene vinyl alcohol resin Is preferred. The ethylene vinyl alcohol resin preferably has a saponification degree of 93% or more, more preferably 96% or more, and an ethylene content of preferably 25 to 50% by mole.

(4) Adhesive layer The resin forming the adhesive layer of the hollow molded article is selected from high density polyethylene, low density polyethylene, linear low density polyethylene etc. graft modified by unsaturated carboxylic acid or its derivative. In particular, it is preferable to be made of high density polyethylene which is graft modified with unsaturated carboxylic acid or its derivative.
The content of unsaturated carboxylic acid or derivative thereof in the resin constituting the adhesive layer is preferably 0.01 to 5% by mass, more preferably 0.01 to 3% by mass, still more preferably 0.01 to 1%. %. When the content of unsaturated carboxylic acid or its derivative is less than 0.01% by mass, sufficient adhesion performance is not expressed, and when it exceeds 5% by mass, unsaturated carboxylic acid which does not contribute to adhesiveness adversely affects the adhesiveness. give.

(5) Reclaimed Material Layer The resin that forms the reclaimed material layer of the hollow molded product is a polyethylene resin that forms the outermost layer, a polyethylene resin that forms the innermost layer, a resin that forms the barrier layer, and a resin that forms the adhesive layer Containing composition.
Each component of the resin forming the recycled material layer can be used as a new product, and unnecessary parts such as scraps and burrs of the multilayer laminate including each layer made of each resin can be recovered and reused for such recycling. An article can also be used as a component raw material of each component. For example, a regrind resin obtained by pulverizing a hollow molded article (car fuel tank product and the like) that has been molded and used and has been used may be mentioned. When molded burrs and unused parisons generated when producing a multilayer laminate are used as recycled materials, the compatibility of the various components may be reduced, so that the compatibilizer and the resin constituting the adhesive layer are further mixed. You may

(6) Layer configuration ratio of hollow molded product The hollow molded product is not limited by the thickness configuration of each layer, but for example, the outermost layer is 10 to 30%, the innermost layer is 20 to 50%, and the barrier layer is 1 to 15 in thickness ratio. %, The adhesive layer is 1 to 15%, and the recycled material layer is 30 to 60% (however, the total of all layer thickness composition ratios is 100%).
The layer constitution ratio of the outermost layer is preferably 10 to 30%, more preferably 10 to 25%, still more preferably 10 to 20%, with respect to the layer thickness of the hollow molded article. If the layer constitution ratio of the outermost layer is less than 10%, the impact performance is insufficient, and if it exceeds 30%, the molding stability of the hollow molded article tends to be impaired.
The layer constitution ratio of the innermost layer is preferably 20 to 50%, more preferably 35 to 50%, still more preferably 40 to 50% with respect to the layer thickness of the hollow molded article. If the layer composition ratio of the innermost layer is less than 20%, insufficient rigidity of the hollow plastic molded article becomes apparent, and if it exceeds 50%, the molding stability of the hollow plastic molded article tends to be impaired.
The layer constitution ratio of the barrier layer is preferably 1 to 15%, more preferably 1 to 10%, still more preferably 1 to 5%, based on the layer thickness of the hollow molded article. If the layer composition ratio of the barrier layer is less than 1%, the barrier performance is unsatisfactory, and if it exceeds 15%, the impact performance tends to be insufficient.
The layer constitution ratio of the adhesive layer is preferably 1 to 15%, more preferably 1 to 10%, still more preferably 1 to 5%, based on the layer thickness of the hollow molded article. If the layer composition ratio of the adhesive layer is less than 1%, the adhesive performance is unsatisfactory, and if it exceeds 15%, the rigidity of the hollow molded article tends to be manifested.
The composition ratio of the recycled material layer is preferably 30 to 60%, more preferably 35 to 50%, and still more preferably 35 to 45% with respect to the layer thickness of the hollow molded article. When the layer composition ratio of the recycled material layer is less than 30%, the molding stability of the hollow plastic molded article is impaired, and when it exceeds 60%, the impact performance tends to be insufficient.

5. Applications of hollow molded articles etc. As applications of the hollow molded article of the present invention, for example, fuel tanks for automobiles, various fuel tanks, kerosene cans, drums, containers for medicines, containers for pesticides, containers for solvents, various plastic bottles etc. It can be mentioned.
The polyethylene-based resin material of the present invention is excellent in moldability as described above, and is excellent in the balance between rigidity and durability. Therefore, even if it is formed as a material of a hollow molded article, particularly as a multilayer structure including a barrier layer, the barrier layer does not have adverse effects such as strength deterioration and molding failure on the polyethylene layer, and is excellent in barrier properties. Furthermore, the polyethylene-based resin material of the present invention is also excellent in swelling resistance when immersed in liquid fuel such as gasoline. Therefore, the hollow molded article using the polyethylene-based resin material of the present invention is suitable for a fuel container which is required to be light in weight and high in durability, in particular, a fuel tank of an automobile.

  EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

1. Various evaluation (measurement) methods (1) Melt flow rate (HLMFR) measured at a temperature of 190 ° C. and a load of 21.6 kg Measured according to JIS K6922-2: 1997.
(2) Density Measured in accordance with JIS K7112: 2004.
(3) Flexural modulus of elasticity Measured in accordance with JIS K7171: 2008.
(4) Melt tension (MT)
Using Capirograph manufactured by Toyo Seiki Seisakusho, nozzle diameter 2.095 mmφ, nozzle length 8.00 mm, inflow angle 180 °, setting temperature 210 ° C., piston extrusion speed 10.0 mm / min, take-up speed 4.0 m / min It measured on condition.

(5) Breaking time according to all around notch type tensile creep test (T)
After compression molding of a 5.9 mm thick sheet in accordance with JIS K-6992-2 (2004 edition), JIS K-6774 (2004 edition) Annex 5 (standard) shown in FIG. Test pieces of the shape and dimensions of 50 "were prepared and subjected to the full notch tensile creep test (FNCT) in pure water at 80 ° C. The tensile load was 88 N, 98 N and 108 N, and the test score was 2 points for each load. The fracture time at a nominal stress of 6 MPa was used as an indicator of creep resistance by the least squares method from the obtained six-point plot of rupture time and nominal stress on a double logarithmic scale.

(6) Suitability of Formula (1) The relationship between the rupture time (T) (unit: time) and the melt tension (MT) (unit: mN) of the all-round notch creep test described in the following formula (1) It was judged whether it satisfied
T ¹⁵ 1530 x e ^{(-0.025 MT)} formula (1)
Here, e is the Napier number (the base of natural logarithms).

(7) Measurement of Molecular Weight by GPC Method The ratio of weight average molecular weight to number average molecular weight was determined under the following conditions. A universal calibration curve was made with monodispersed polystyrene and calculated as the molecular weight of linear polyethylene.
Apparatus: Alliance GPC V2000 type manufactured by WATERS, Inc. Column: Two HT-806M manufactured by Showa Denko + 1 HT-G Measurement temperature: 145 ° C.
Concentration: 1 mg / 1 ml
Solvent: o-dichlorobenzene In addition, calculation of molecular weight and calibration of a column can be performed based on the following method.
GPC chromatography data is read into a computer at a frequency of 1 point / second, data processing is performed as described in “Size Exclusion Chromatography”, published by Mori Sadao, Kyoritsu Publishing Co., and Mw and Mn values are calculated. Can. The conversion from the measurement retention volume to the molecular weight was performed using a calibration curve with standard polystyrene prepared in advance.

(8) Melt fracture Melt fracture was measured in accordance with JIS K 7919: 1999 (ISO 11443: 1995). Melt fracture occurs using CAPIROGRAPH 1B manufactured by Toyo Seiki Seisakusho, measuring at a piston extrusion speed of 20.0 mm / min with a nozzle diameter of 1.0 mmφ, a nozzle length of 40 mm, an inflow angle of 90 °, and a preset temperature of 210 ° C. The thing which was not done was made into "(circle)" and the thing which generate | occur | produced as "x".

(9) Drawdown resistance A fuel tank for an automobile is hollow molded, and the drawdown and thickness uniformity of the parison are evaluated, and a good one is "○", molding failure occurs, or thickness is not defective. Those with a relatively large distribution were taken as "x".

(10) Swelling rate The swelling rate is measured by immersing the test piece in Fuel C fuel (isooctane / toluene = 50/50% by volume) at 60 ° C for 168 hours, measuring the weight change before and after immersion, and the weight before immersion The weight change rate as a standard was determined. In addition, the test piece used the thing of length 80.0 mm, width 10.0 mm, and thickness 4.0 mm.

(11) Dimensional change rate The dimensional change rate was measured by immersing the test piece in Fuel C's fuel (isooctane / toluene = 50/50% by volume) at 60 ° C for 168 hours, measuring the dimensional change before and after immersion, and before immersion The dimensional change rate was determined based on the size. In addition, the test piece used the thing of length 80.0 mm, width 10.0 mm, and thickness 4.0 mm.

(12) Flexural modulus after fuel immersion For flexural modulus after fuel immersion, immerse the test piece for flexural modulus measurement in Fuel C's fuel (isooctane / toluene = 50/50% by volume) at 60 ° C for 168 hours. The flexural modulus was measured according to JIS K7171: 2008 for the flexural modulus test pieces after fuel immersion.

(13) Durability of Fuel Tank A fuel tank having a breaking time (T) of 60 hours or more according to the all around notch type tensile creep test was regarded as good "o", and one having less than 60 hours was regarded as "x".

(14) Overall Evaluation In the above evaluation, melt fracture does not occur, drawdown resistance is good, swelling rate is 10% or less, dimensional change rate is 4.0% or less, flexural modulus after fuel immersion A fuel tank having a durability of 340 MPa or more and a fuel tank having good durability was evaluated as "o", and the others were evaluated as "x".

2. Preparation of material used (Preparation of solid catalyst component)
20 g of commercially available magnesium ethylate (average particle diameter 860 μm) in a nitrogen atmosphere in a 1 L pot (container for grinding) containing about 700 magnetic balls each having a diameter of 10 mm, granular aluminum trichloride 1. 66 g and 2.72 g of diphenyldiethoxysilane were added. These were subjected to co-grinding for 3 hours under the conditions of an amplitude of 6 mm and a frequency of 30 Hz using a vibrating ball mill. After co-grinding, the contents were separated from the magnetic balls under a nitrogen atmosphere.
5 g of the co-ground product obtained as described above and 20 ml of n-heptane were added to a 200 ml three-necked flask. While stirring, 10.4 ml of titanium tetrachloride was added dropwise at room temperature, the temperature was raised to 90 ° C., and stirring was continued for 90 minutes. Then, after cooling the reaction system, the supernatant was withdrawn and n-hexane was added. This operation was repeated three times. The obtained pale yellow solid was dried at 50 ° C. under reduced pressure for 6 hours to obtain a solid catalyst component.

Example 1
[Manufacture of polyethylene resin material]
The two-stage polymerization reactor, in which two pipe loop reactors in the former stage of 145 liters and the latter stages of 290 liters were connected in series, was thoroughly purged with nitrogen. Next, isobutane is supplied to fill the inside of the reactor with isobutane, and then triisobutylaluminum is supplied so that the concentration in the pre-reactor becomes 1.0 mmol / L, and the front-reactor is heated to 80 ° C. with stirring. The reactor was heated to 90 ° C.
Next, ethylene was added so that the concentration in the former reactor was 1.0 vol% and the concentration in the latter reactor was 2.6 vol%, and the first hydrogen / ethylene ratio was 0.002 vol%, 1-hexene. Hydrogen was supplied to the first and second stages, and 1-hexene was supplied to the first stage only, so that the / ethylene ratio was 0.80 vol% and the second-stage hydrogen / ethylene ratio was 0.09 vol%.
Then, the polymerization was started by continuously feeding the first stage continuously so that the feed rate of the solid catalyst component obtained by the above method was 2.0 g / hour. While continuously supplying isobutane to the former reactor at 51.5 kg / hour and further to the latter reactor at 34.0 kg / hour, it was operated so that the polymer polymerization ratio of the former and latter is 30/70. The stage-polymerized ethylene-based polymer was discharged at 20 kg / hour from the latter stage. During operation, the concentration of triisobutylaluminum in the former stage, the concentration of ethylene and hydrogen in the former and latter reactors, and the temperature were maintained. The discharged isobutane slurry of the ethylene polymer was evaporated at normal pressure to evaporate the isobutane and then dried by a conveyor dryer at 80 ° C.
The HLMFR of the component obtained in the first stage reactor was 0.05 g / 10 min, and the density was 0.926 g / cm ³ . The MFR and density of the ethylene-based polymer produced in the second stage were determined by separately polymerizing under the second stage polymerization conditions, and the density was 0.966 cm ³ at an MFR of 10 g / min.
0.05% by mass of a phenolic antioxidant (manufactured by BASF Japan, Irganox 1010), and 0.15% by mass of a phosphorous antioxidant (manufactured by BASF Japan, Irgafos 168) in powder after two-stage polymerization, After the addition of 0.15% by mass of calcium stearate, the obtained polyethylene resin material had an HLMFR of 5.8 g / 10 min and a density of 0.954 g / cm ³ .

[Physical properties and evaluation of polyethylene resin material]
Physical properties and evaluation results of the polyethylene resin material described above are shown in Table 1. The obtained polyethylene resin material is excellent in hollow moldability by appropriate fluidity and high melt tension, excellent in appearance of molded product, excellent in balance of rigidity and durability, and swelling resistance when immersed in liquid fuel such as gasoline It was also excellent in sex.

[Example 2] to [Example 5]
The same procedure as in Example 1 was carried out except that the composition shown in Table 1 was used. Physical properties and evaluation results of the polyethylene resin material are shown in Table 1. The obtained polyethylene resin material is excellent in hollow moldability by appropriate fluidity and high melt tension, excellent in appearance of molded product, excellent in balance of rigidity and durability, and swelling resistance when immersed in liquid fuel such as gasoline It was also excellent in sex.

[Comparative Example 1] to [Comparative Example 7]
The same procedure as in Example 1 was carried out except that the composition shown in Table 1 was used. Physical properties and evaluation results of the polyethylene resin material are shown in Table 1.

[Reference Example 1]
The same procedure as in Example 1 was carried out except that the composition shown in Table 1 was used. Physical properties and evaluation results of the polyethylene resin material are shown in Table 1.

[Reference Example 2]
The procedure of Example 1 was repeated except that a metallocene catalyst was used and the composition was as shown in Table 1. Physical properties and evaluation results of the polyethylene resin material are shown in Table 1.

3. Evaluation The experimental results will be described with reference to the experimental results shown in Table 1.
The polyethylene resin materials of Examples 1 to 5 have an HLMFR of 4.9 to 8.6 g / 10 min and an MT of 128 to 151 mN, so they are excellent in drawdown resistance and melt fracture does not occur. The molding stability was good, and the appearance of the molded product was also excellent. The polyethylene resin materials of Examples 1 to 5 have a density of 0.951 to 0.954 g / cm ³ and an FNCT of 73 to 110 hours, so they are excellent in terms of balance between rigidity and durability. It was Furthermore, the polyethylenes of Examples 1 to 5 show a low swelling ratio during liquid fuel immersion, a low dimensional change ratio, a high flexural modulus after fuel immersion, and excellent results for fuel tank suitability. The
On the other hand, in the polyethylene-based resin material of Comparative Example 1, the composition ratio of the ethylene-based polymer (A) as the high molecular weight component was small, the FNCT was 43 hours, and the durability of the fuel tank was inferior.
In the polyethylene resin material of Comparative Example 2, the HLMFR of the polyethylene resin material was small, and melt fracture occurred.
The polyethylene-based resin material of Comparative Example 3 had a large HLMFR of the polyethylene-based resin material, a large MT, and a poor drawdown resistance.
In the polyethylene-based resin material of Comparative Example 4, the density of the polyethylene-based resin material was low, the flexural modulus after immersion in fuel oil was small, and the fuel tank suitability was poor.
In the polyethylene resin material of Comparative Example 5, the density of the polyethylene resin material was high, the FNCT was small, and the durability of the fuel tank was inferior.
In the polyethylene-based resin material of Comparative Example 6, the density of the ethylene-based polymer (A) which is a high molecular weight component was high, the FNCT was small, and the durability of the fuel tank was inferior.
In the polyethylene-based resin material of Comparative Example 7, the HLMFR of the ethylene-based polymer (A) as the high molecular weight component was large, the FNCT was small, and the durability of the fuel tank was inferior.
In the polyethylene resin material of Reference Example 1, the MFR of the ethylene polymer (B), which is a low molecular weight component, is large, the swelling ratio in liquid fuel immersion is high, the flexural modulus after fuel oil immersion is small, the fuel tank The aptitude was poor.
In the polyethylene-based resin material of Reference Example 2, the Mw / Mn of the ethylene-based polymer (B) which is a low molecular weight component was small, and a melt fracture occurred.

  The polyethylene-based resin material of the present invention is excellent in balance of rigidity and durability, excellent in moldability and appearance of a molded product, and particularly provides a material excellent in swelling resistance when immersed in liquid fuel such as gasoline. Hollow plastic moldings using it have similar good properties and can be used for containers, bottles, cans, tanks etc., particularly useful materials for hollow plastic products such as automotive fuel tanks etc. Since it can be provided, it is extremely useful in industry.

Claims (6)

It contains one or more ethylene polymers selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and an α-olefin having 3 to 12 carbon atoms as essential components, and the following properties [a] , [B], [c] and [d].
[A] The melt flow rate (HLMFR) measured at a temperature of 190 ° C. and a load of 21.6 kg is 4 to 10 g / 10 min.
[B] The density is 0.950 to 0.955 g / cm ³ .
[C] Melt tension (MT) measured at 210 ° C. is 120 mN or more.
[D] The rupture time (T) of the all-round notch creep test is at least 60 hours. The polyethylene resin material according to claim 1, comprising 30 to 50% by mass of the following ethylene-based polymer (A) and 70 to 50% by mass of the following ethylene-based polymer (B) as the essential components.
Ethylene polymer (A): ethylene polymer having a density of 0.920 to 0.935 g / cm ³ and an HLMFR of 0.01 to 0.5 g / 10 min.
Ethylene-based polymer (B): an ethylene-based polymer having a density of 0.960 to 0.980 g / cm ³ , a melt flow rate (MFR) of 1 to 200 g / 10 min measured at a temperature of 190 ° C. and a load of 2.16 kg Polymer.   The ethylene polymer (A) has a molecular weight distribution represented by a ratio (Mw / Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) method The polyethylene resin material according to claim 2, wherein is 2 to 10.   The polyethylene resin material according to claim 2 or 3, wherein the ethylene polymer (B) has a molecular weight distribution (Mw / Mn) of 5-15.   The hollow molded article which has a layer which consists of a polyethylene-type resin material as described in any one of Claims 1-4.   The hollow molded article according to claim 5, which is at least one selected from the group consisting of a fuel tank, a kerosene can, a drum, a container for chemicals, a container for pesticides, a container for solvents and a plastic bottle.