JPH08188681A - Polyethylene resin composition - Google Patents

Abstract

PURPOSE: To obtain a polyethylene resin compsn. which is excellent in processibility and heat seal strength and can be heat-sealed at a low temp. by compounding a specific ethylene-α-olefin copolymer with a specific lowdensity polyethylene produced by high-pressure free-radical polymn. CONSTITUTION: This resin compsn. comprises 90-60wt.% ethylene-3C or higher α-olefin copolymer having a density of 0.880-0.920g/cm<3> , a specified melt flow rate, a specified ratio of wt.-average mol.wt. to number-average mol.wt., the number of short-chain branches per 1,000 carbon atoms satisfying a specified relation, and a Tn ( deg.C) lower than that of a specific low-density polyethylene and 10-40wt.% low-density polyethylene having a density of 0.910-0.935g/cm<3> and a melt flow rate of 1.0-20g/10min at 190 deg.C under 2,160g-load and produced by high-pressure free-radical polymn.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyethylene resin composition. More specifically, the present invention relates to a polyethylene resin composition which is excellent in processability, has a high heat-sealing strength, and is suitable as a heat-sealing material in an extrusion laminate material that can be heat-sealed at a high speed, that is, at a low temperature.

[0002]

2. Description of the Related Art Low-density polyethylene (hereinafter referred to as HP-LDPE) obtained by a high-pressure radical polymerization method has a long-chain branch in its molecular chain, so that it can be easily extruded by a general extruder and T- A very stable molten film is obtained in the die. Further, the melted film has a sufficient drawdown property, and in order to adhere well to the substrate, it is extrusion laminated on paper, non-woven fabric, plastic film, metal foil, etc., and is widely used mainly for packaging materials. .

However, if there is a long-chain branch in the molecular chain, the peel strength of the heat-sealed portion (hereinafter referred to as heat-sealed strength) becomes small, so that HP-LDPE has a large heat-sealed strength like water packaging. It could not be used in the required fields, and its range of use was limited despite its excellent processability.

On the other hand, an ethylene / α-olefin copolymer obtained by a conventionally known Ziegler type catalyst is known as one having a large heat seal strength. However, these do not have long chain branching in the molecular chain, and therefore have higher melt shear viscosity and extremely poor extrusion processability as compared with HP-LDPE having the same melt flow rate. Further, the elongational viscosity is very small and the melt tension is small. Therefore, in extrusion lamination processing, there is a drawback that the extruder is heavily loaded, the film-forming property on the T-die is unstable, that is, the stability of the ears is poor, and the neck-in is large.

From the above, ethylene / α-olefin copolymer and HP- are used as the heat seal material in the actual extrusion laminate material for the purpose of utilizing their respective characteristics.
A blend of LDPE has been used. The mixed composition of both is ethylene / α- so that the respective characteristics are maintained.
The weight ratio of the olefin copolymer and HP-LDPE is 80 /
It is often set at 20 to 60/40. That is,
This means that 80 to 60% by weight of ethylene / α-olefin copolymer is required in terms of heat seal strength and 20 to 40% by weight of HP-LDPE is required in terms of processed surface.
A very important point here is that in the blend of the ethylene / α-olefin copolymer and HP-LDPE, in order for the characteristics of the heat seal strength of the ethylene / α-olefin copolymer to be exhibited, HP -The LDPE has to melt. In other words, ethylene /
Even if the α-olefin copolymer melts at a very low temperature, HP-LDPE mixed for the purpose of imparting processability
In the case of melting at a high temperature, the heat-sealing strength of the ethylene / α-olefin copolymer is not expressed until the HP-LDPE melts. In addition to the above-mentioned processability and heat-sealing strength, it is a very important required property that the heat-sealing material of the innermost layer in the extrusion laminate material can be heat-sealed at a high speed, but for that purpose, it can be heat-sealed at a lower temperature. Will be required. Therefore, it is necessary to select HP-LDPE having a low melting point in order to obtain a product having good workability, high heat-sealing strength, and heat-sealing at a high speed, that is, at a low temperature. However, since the melting point of HP-LDPE is limited in lowering the temperature, at present, there is a limit to the processability and the high heat-sealing strength. there were.

[0006]

The present invention is based on ethylene /
In the composition of α-olefin copolymer and HP-LDPE, by moving the melting point of the HP-LDPE component to the low temperature side, the workability is good, the heat seal strength is high, and the heat seal can be performed at a high speed, that is, at a low temperature. It is an object of the present invention to provide a polyethylene resin composition suitable for a heat seal material and the like in an extrusion laminate material which has never been available.

[0007]

As an ethylene / α-olefin copolymer used for a heat seal material or the like in an extrusion laminate material, one obtained by a Ziegler type catalyst is known, and this is generally used. There is.
However, with the advent of new catalysts, ethylene / α, which has a narrower molecular weight distribution and composition distribution than ever before, is recently available.
-Olefin copolymers have become available. Based on such a situation, as a result of intensive studies to solve the above problems, ethylene / α having a specific density range, a narrow molecular weight distribution and a narrow compositional distribution, and a lower melting point than HP-LDPE. -Olefin copolymer and HP-L
It was found that blending DPE shifts the melting point of LDPE to the low temperature side. By making use of this characteristic, in these compositions, in addition to the conventionally known characteristics of workability and heat sealing strength, it is suitable for a heat sealing material or the like in an extrusion laminate material capable of heat sealing at a higher speed, that is, a lower temperature. A polyethylene resin composition not found in the above can now be obtained.

That is, according to the present invention, (a) the density is 0.8
It is in the range of 80 to 0.920 g / cm ³ , and (b) 19
The melt flow rate (MFR) measured under 0 ° C. and a load of 2160 g is in the range of 1.0 to 50 g / 10 minutes,
(C) Weight average molecular weight (Mw) and number average molecular weight (Mn)
Ratio (Mw / Mn) of 3 or less, (d) in a differential scanning calorimeter, melting at 200 ° C. for 5 minutes, and then 10
The temperature at the maximum peak position of the endothermic curve (Tm (° C.)) obtained when the temperature of the product cooled to 30 ° C. at 30 ° C./min was raised again at 10 ° C./min and the number of carbon atoms 1000 determined from the measurement of infrared absorption spectrum Number of short chain branches (SCB)
And satisfy the relationship represented by the formula (1), and Tm <−1.8 × SCB + 138 (1) (e) Tm (° C.) is lower than the low-density polyethylene obtained by the high-pressure radical polymerization method described below. A copolymer [A] with an α-olefin having 3 or more carbon atoms, and (f)
The density is 0.910 to 0.935 g / cm ³ or more,
(G) a low density polyethylene [B] obtained by a high pressure radical polymerization method, which has a melt flow rate (MFR) measured under a load of 190 ° C. and 2160 g in the range of 1.0 to 20 g / 10 minutes, h) The present invention relates to a polyethylene resin composition characterized in that a weight ratio of [A] / [B] is 90/10 to 60/40.

The ethylene / α-olefin copolymer [A] has a density in the range of 0.880 to 0.920 g / cm ³ . If the density exceeds 0.920 g / cm ³ ,
The melting point of the ethylene / α-olefin copolymer itself becomes high, and in the blending with [B], the melting point of [B] does not move to the low temperature side, and the desired effect cannot be obtained. On the other hand, if the density is less than 0.880 g / cm ³ ,
It is not preferable because the self-adhesiveness of the film increases and blocking occurs.

The ethylene / α-olefin copolymer has a melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g in the range of 1.0 to 50 g / 10 minutes. When the MFR is less than 1.0 g / 10 minutes, the melt shear viscosity becomes high, the load on the extruder becomes large, and the drawdown property becomes poor, which is not preferable. On the other hand, when it is more than 50 g / 10 minutes, the stability of the ears is poor and the neck-in is large, resulting in poor film formation stability.

Further, the ethylene / α-olefin copolymer has a weight average molecular weight (Mw) and a number average molecular weight (M
The ratio (Mw / Mn) of n) is 3 or less. When Mw / Mn exceeds 3, the low molecular weight component that causes stickiness increases, which is not preferable. Also, this ethylene / α-
The olefin copolymer is such that Tm (° C.) and the number of short chain branches (SCB) per 1000 carbon atoms obtained from measurement of infrared absorption spectrum satisfy the relationship of the formula (1). An ethylene / α-olefin copolymer that does not satisfy this formula has a wide composition distribution and has many low-density (high branch number) components that cause stickiness, which is not preferable.

Tm <−1.8 × SCB + 138 (1) Furthermore, this ethylene / α-olefin copolymer has a T
HP-LDP in which m (° C) is the other component of the composition
It is lower than E. When Tm (° C) is higher than that of HP-LDPE, the melting point of HP-LDPE in the composition does not move to a lower temperature, and the desired effect cannot be obtained.

The ethylene / α-olefin copolymer [A] described above has, for example, a so-called metallocene compound and a compound capable of ionizing a metallocene compound to form a cationic metallocene compound as a basic constituent component. Can be obtained using a catalyst system The catalyst system and the polymerization method are illustrated below, but the method for producing the ethylene / α-olefin copolymer [A] in the present invention is not limited thereto.

As an example of the method for polymerizing the ethylene / α-olefin copolymer in the present invention, for example, polymerization is carried out using a catalyst system containing a specific metallocene compound, an organoaluminum compound and an ionizable ionic compound as basic components. A method can be mentioned.

Specifically, the metallocene compound is represented by the following general formula (2) or (3), the organoaluminum compound is represented by the following general formula (4), and an ionized ionic compound is used as a basic constituent component. An example of the catalyst system is as follows.

The general formula (2) or (3) is

[0017]

Embedded image

[0018]

Embedded image

(In the formula, Cp ¹ and Cp ² are each independently a cyclopentadienyl group, an indenyl group, a fluorenyl group or a substitution product thereof, and R ¹ acts to crosslink Cp ¹ and Cp ^2. A substituted or unsubstituted alkylene group, a dialkylsilanediyl group, a dialkylgermandiyl group, an alkylphosphinediyl group or an alkylimino group, and R ² and R ³ are each independently a hydrogen atom, a halogen atom or a carbon atom. A hydrocarbon group, an alkoxy group or an aryloxy group of the formulas 1 to 12, M is a titanium atom, a zirconium atom or a hafnium atom), and specific compounds thereof include bis ( Cyclopentadienyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, bis (butyl) Cyclopentadienyl) zirconium dimethyl, ethylenebis (indenyl) zirconium dimethyl, isopropylidene (cyclopentadienyl -1
-Fluorenyl) zirconium dimethyl, dimethylsilanediylbis (2,4,5-trimethylcyclopentadienyl) zirconium dimethyl, dimethylsilanediylbis (2,4-dimethylcyclopentadienyl) zirconium dimethyl, dimethylsilanediylbis (3 -Methylcyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium dichloride,
Bis (methylcyclopentadienyl) zirconium dichloride, bis (butylcyclopentadienyl) zirconium dichloride, ethylenebis (indenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-1-fluorenyl) zirconium dichloride, dimethylsilanediylbis ( 2,4,5-Trimethylcyclopentadienyl) zirconium dichloride, dimethylsilanediylbis (2,4-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilanediylbis (3-methylcyclopentadienyl) zirconium dichloride, bis (Cyclopentadienyl) zirconium diphenyl, bis (methylcyclopentadienyl) zirconium diphenyl, bis (butylcyclopentadienyl) ) Zirconium diphenyl, ethylenebis (indenyl) zirconium diphenyl, isopropylidene (cyclopentadienyl-1-fluorenyl) zirconium diphenyl, dimethylsilanediylbis (2,4,5-trimethyl cyclopentadienyl)
Zirconium diphenyl, dimethylsilanediyl bis
(2,4-Dimethylcyclopentadienyl) zirconium diphenyl, dimethylsilanediylbis (3-methylcyclopentadienyl) zirconium diphenyl, bis (cyclopentadienyl) zirconium dibenzyl, bis (methylcyclopentadienyl) Zirconium dibenzyl, bis (butylcyclopentadienyl) zirconium dibenzyl, ethylene bis (indenyl) zirconium dibenzyl, isopropylidene (cyclopentadienyl-1-fluorenyl) zirconium dibenzyl, dimethylsilanediylbis (2,4,4) 5-trimethylcyclopentadienyl) zirconium dibenzyl, dimethylsilanediylbis (2,4-dimethylcyclopentadienyl) zirconium dibenzyl, dimethylsilanediylbis (3-methylcyclo) Bis (cyclopentadienyl) zirconium methoxymonochloride, bis (methylcyclopentadienyl) zirconium methoxymonochloride, bis (butylcyclopentadienyl) zirconium methoxymonochloride, ethylenebis (indenyl) zirconium Methoxy monochloride, isopropylidene (cyclopentadienyl-1-fluorenyl) zirconium methoxy monochloride, dimethylsilanediylbis (2,4,5-trimethylcyclopentadienyl) zirconium methoxymonochloride, dimethylsilanediylbis (2,2 4-dimethylcyclopentadienyl) zirconium methoxymonochloride, dimethylsilanediylbis (3-methylcyclopentadienyl) zirconium methoxy Monochloride, bis (cyclopentadienyl) methylzirconium monochloride, bis (methylcyclopentadienyl) methylzirconium monochloride, bis (butylcyclopentadienyl) methylzirconium monochloride, ethylenebis (indenyl) methylzirconium monochloride , Isopropylidene (cyclopentadienyl-1-fluorenyl) methyl zirconium monochloride, dimethylsilanediylbis (2,4,5-trimethylcyclopentadienyl) methylzirconium monochloride, dimethylsilanediylbis (2,4-dimethyl) Cyclopentadienyl) methylzirconium monochloride, dimethylsilanediylbis (3-methylcyclopentadienyl)
Methyl zirconium monochloride, isopropylidene (cyclopentadienyl) (fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (fluorenyl) zirconium dichloride,
Methylphenylmethylene (cyclopentadienyl) (fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (2,7-dimethylfluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (2,7-dimethyl Fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-di-t-butylfluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-di-methylfluorene Nyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-di-t
-Butylfluorenyl) zirconium dichloride, methylphenylmethylene (cyclopentadienyl) (2,
7-di-methylfluorenyl) zirconium dichloride, methylphenylmethylene (cyclopentadienyl)
(2,7-di-t-butylfluorenyl) zirconium dichloride, isopropylidenebis (cyclopentadienyl) zirconium dichloride, diphenylmethylenebis (cyclopentadienyl) zirconium dichloride, methylphenylmethylenebis (cyclopentadienyl) ) Zirconium dichloride, isopropylidene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, isopropylidene bis (indenyl) zirconium dichloride ,
Examples thereof include diphenylmethylenebis (indenyl) zirconium dichloride, methylphenylmethylenebis (indenyl) zirconium dichloride and the like, and metallocene compounds in which the zirconium atom of the zirconium compound is replaced with a titanium atom or a hafnium atom.

The general formula (4) is represented by AlR ⁴ ₃ (4) (wherein, R ⁴ is independently a hydrogen atom, a halogen atom,
It is an amide atom, a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group or an aryloxy group, and at least one is a hydrocarbon group having 1 to 12 carbon atoms. ), Specific examples of these compounds include trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, diisopropyl aluminum chloride, isopropyl aluminum dichloride, tributyl aluminum, triisobutyl aluminum, diisobutyl aluminum chloride, isobutyl aluminum dichloride, and tri (t -Butyl) aluminum, di (t-butyl) aluminum chloride, t-butylaluminum dichloride, triamylaluminum, diamylaluminum chloride, amylaluminum dichloride and the like, but are not limited thereto.

Specific examples of the ionized ionic compound include tri (n-butyl) ammonium tetrakis (p-tolyl) borate, tri (n-butyl) ammonium tetrakis (m-tolyl) borate, tri (n). -Butyl) ammonium tetrakis (2,4-dimethylphenyl) borate, tri (n-butyl) ammonium tetrakis (3,5-dimethylphenyl) borate, tri (n-butyl) ammonium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (p-tolyl) borate, N, N-
Dimethylanilinium tetrakis (m-tolyl) borate, N, N-dimethylanilinium tetrakis (2,4)
-Dimethylphenyl) borate, N, N-dimethylanilinium tetrakis (3,5-dimethylphenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, triphenylcarbenium tetrakis (p-tolyl) borate , Triphenylcarbenium tetrakis (m-tolyl) borate, triphenylcarbenium tetrakis (2,4-dimethylphenyl) borate, triphenylcarbenium tetrakis (3,5-dimethylphenyl) borate, triphenylcarbenium tetrakis (penta Fluorophenyl)
Borate, tropylium tetrakis (p-tolyl) borate, tropylium tetrakis (m-tolyl) borate, tropylium tetrakis (2,4-dimethylphenyl) borate, tropylium tetrakis (3,5-dimethylphenyl) borate, tropylium Tetrakis (pentafluorophenyl) borate, lithium tetrakis (pentafluorophenyl) borate, lithium tetrakis (phenyl) borate, lithium tetrakis (p-
Trilyl) borate, lithium tetrakis (m-tolyl)
Borate, lithium tetrakis (2,4-dimethylphenyl) borate, lithium tetrakis (3,5-dimethylphenyl) borate, lithium tetrafluoroborate, sodium tetrakis (p-tolyl) borate, sodium tetrakis (m-tolyl) borate, sodium Tetrakis (2,4-dimethylphenyl) borate,
Sodium tetrakis (3,5-dimethylphenyl) borate, sodium tetrafluoroborate, potassium tetrakis (pentafluorophenyl) borate, potassium tetrakis (phenyl) borate, potassium tetrakis (p-tolyl) borate, potassium tetrakis (m
-Tolyl) borate, potassium tetrakis (2,4-dimethylphenyl) borate, potassium tetrakis (3,3)
5-dimethylphenyl) borate, potassium tetrafluoroborate, magnesium tetrakis (pentafluorophenyl) borate, magnesium tetrakis (phenyl) borate, magnesium tetrakis (p-tolyl) borate, magnesium tetrakis (m-tolyl)
Borate, magnesium tetrakis (2,4-dimethylphenyl) borate, magnesium tetrakis (3,5-)
Dimethylphenyl) borate, magnesium tetrafluoroborate, calcium tetrakis (phenyl) borate, calcium tetrakis (p-tolyl) borate,
Calcium tetrakis (m-tolyl) borate, calcium tetrakis (2,4-dimethylphenyl) borate, calcium tetrakis (3,5-dimethylphenyl) borate, calcium tetrafluoroborate, tri (n-butyl) ammonium tetrakis (p-tolyl) ) Aminate, tri (n-butyl) ammonium tetrakis (m-tolyl) aminate, tri (n-butyl)
Ammonium tetrakis (2,4-dimethylphenyl)
Aluminate, tri (n-butyl) ammonium tetrakis (3,5-dimethylphenyl) aluminate, tri (n-butyl) ammonium tetrakis (pentafluorophenyl) aluminate, N, N-dimethylanilinium tetrakis (p-tolyl) ) Aluminate, N, N-
Dimethylanilinium tetrakis (m-tolyl) aluminate, N, N-dimethylanilinium tetrakis (2,4-dimethylphenyl) aluminate, N, N-
Dimethylanilinium tetrakis (3,5-dimethylphenyl) aluminate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) aluminate,
Triphenylcarbenium tetrakis (p-tolyl) aluminate, triphenylcarbenium tetrakis (m
-Tolyl) aluminate, triphenylcarbenium tetrakis (2,4-dimethylphenyl) aluminate,
Triphenylcarbenium tetrakis (3,5-dimethylphenyl) aluminate, triphenylcarbenium tetrakis (pentafluorophenyl) aluminate,
Tropylium tetrakis (p-tolyl) aluminate,
Tropylium tetrakis (m-tolyl) aluminate,
Tropylium tetrakis (2,4-dimethylphenyl)
Aluminate, tropylium tetrakis (3,5-dimethylphenyl) aluminate, tropylium tetrakis (pentafluorophenyl) aluminate, lithium tetrakis (pentafluorophenyl) aluminate, lithium tetrakis (phenyl) aluminate, lithium tetrakis (p -Tolyl) aluminate, lithium tetrakis (m-tolyl) aluminate, lithium tetrakis (2,4-dimethylphenyl) aluminate, lithium tetrakis (3,5-dimethylphenyl) aluminate, lithium tetrafluoroaluminate, sodium tetrakis (Pentafluorophenyl) aluminate,
Sodium tetrakis (phenyl) aluminate, sodium tetrakis (p-tolyl) aluminate, sodium tetrakis (m-tolyl) aluminate, sodium tetrakis (2,4-dimethylphenyl) aluminate, sodium tetrakis (3,5-dimethylphenyl) ) Aluminate, sodium tetrafluoroaluminate, potassium tetrakis (pentafluorophenyl)
Aluminate, potassium tetrakis (p-phenyl) aluminate, potassium tetrakis (m-tolyl) aluminate, potassium tetrakis (2,4-dimethylphenyl) aluminate, potassium tetrakis (3,5-dimethylphenyl) aluminate, potassium Tetrafluoroaluminate, magnesium tetrakis (pentafluorophenyl) aluminate, magnesium tetrakis (phenyl) aluminate, magnesium tetrakis (p-tolyl) aluminate, magnesium tetrakis (m-tolyl) aluminate, magnesium tetrakis (2,4-) Dimethylphenyl) aluminate, magnesium tetrakis (3,5-dimethylphenyl) aluminate, magnesium tetrafluoroaluminate, calcium tetrakis (pet Tafluorophenyl) aluminate, calcium tetrakis (phenyl) aluminate, calcium tetrakis (p-tolyl) aluminate, calcium tetrakis (m-tolyl) aluminate, calcium tetrakis (2,4-dimethylphenyl) aluminate, calcium tetrakis Examples thereof include, but are not limited to, (3,5-dimethylphenyl) aluminate, calcium tetrafluorophenylaluminate and the like, and ether complexes of these metal salts, tetrahydrofuran complexes and the like.

The method of preparing the above catalyst system is not particularly limited, and examples thereof include a method of mixing each of the metallocene compound, the organoaluminum compound and the ionized ionic compound in an inert solvent.

The ionized ionic compound is generally used in a range of 0.01 to 1000 times mol, preferably 0.2 to 200 times mol, of the metallocene compound. The amount of organoaluminum used is not particularly limited, but is usually 1 to 10 relative to the metallocene compound.
It is used in a molar amount of about 000.

Further, the polymerization using the above catalyst system can be carried out in the liquid phase or the gas phase. If the polymerization is carried out in a liquid phase, any organic solvent generally used as a solvent may be used, and specifically, benzene, toluene,
Hexane, methylene chloride and the like can be mentioned. Further, ethylene or α-olefin itself can be used as the solvent.

As the α-olefin having 3 or more carbon atoms,
Propylene, butene-1, pentene-1, hexene-
1, octene-1, 4-methylpentene-1 and the like, and of these, one type or two or more types are used.

There is no particular limitation on the polymerization temperature,
Usually, it is preferably carried out in the range of -100 to 300 ° C.
The polymerization pressure is not particularly limited, but is usually atmospheric pressure to 30 kgf / cm ² , but atmospheric pressure to 35 kg.
It is also possible to carry out in the range of 00 kgf / cm ² .

The above catalyst system may be used as a solid catalyst supported on a carrier, and ethylene / α-olefin copolymer of the present invention may be obtained by copolymerizing ethylene and α-olefin having 3 or more carbon atoms. it can. Such a solid catalyst is a metallocene compound, a mixture of a metallocene compound and an ionized ionic compound, a reaction product of a metallocene compound and an organoaluminum compound, an ionized ionic compound itself, or an organoaluminum compound itself, for example, silica, Alumina, magnesium chloride,
It can be obtained by deposition on a carrier such as styrene-divinylbenzene copolymer or polyethylene.

Next, the low density polyethylene (HP-LDP) obtained by the high pressure radical polymerization method [B] in the present invention.
E) has a density of 0.910 to 0.935 g / cm ³ or more. If the density is less than 0.910 g / cm ³ , blocking of the film occurs, which is not preferable. When the density is higher than 0.935 g / cm ³ , HP-L
Since the melting point of DPE itself is high, the temperature of the composition with [A] is also high, and heat sealing cannot be performed at high speed (low temperature).

[B] HP-LDPE is 1
The melt flow rate (MFR) measured at 90 ° C. under a load of 2160 g is in the range of 1.0 to 20 g / 10 minutes. If the MFR is less than 1.0 g / 10 minutes, the drawdown property will be poor, and if it is more than 20 g / 10 minutes, the neck-in will be large, which is not preferable.

[B] HP-LDPE can be obtained by a conventionally known high-pressure radical polymerization method.

The composition of the present invention comprises ethylene / α-olefin copolymer [A] and HP-LDPE [B] [A] /
[B] It can be produced by mixing in a weight ratio of 90/10 to 60/40.

As the ethylene / α-olefin copolymer [A] and HP-LDPE [B], one kind or a mixture of two or more kinds is used.

The polyethylene resin composition of the present invention comprises an ethylene / α-olefin copolymer [A] and HP-.
Although it may be a dry blend with LDPE [B],
A melt-kneaded product using an extruder, a kneader, a Banbury machine or the like is preferable because a product having stable quality can be obtained.

The polyethylene resin composition of the present invention may further contain additives generally used in polyolefin resins, such as antioxidants, weather resistance stabilizers, antistatic agents, lubricants and blocking agents. You may add it.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Ethylene / α in Examples and Comparative Examples
As the olefin copolymer [A], an ethylene / butene-1 copolymer and an ethylene / hexene-1 copolymer were used. The catalyst system used to obtain these is diphenylmethylene (cyclopentadienyl) (fluorenyl) zirconium dichloride as a metallocene compound,
The ionized ionic compound is N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, and the organoaluminum compound is triisobutylaluminum, and the amounts of the metallocene compound, the ionized ionic compound and the organoaluminum are in a molar ratio (metallocene compound). : Ionized ionic compound: organoaluminum) and the ratio is 1: 2: 250. Toluene was used as a solvent for the preparation of the catalyst. Ethylene used here /
The α-olefin copolymer is obtained by polymerization using the above catalyst system at a polymerization temperature of 165 ° C. and a polymerization pressure of 900 kgf / cm ² . The polymerization operation, reaction and solvent purification were all carried out in an inert gas atmosphere. All the solvents and the like used in the reaction were previously purified, dried and deoxygenated by known methods, and the compounds used in the reaction were those synthesized and identified by known methods.

As the low-density polyethylene [B] in the examples and comparative examples, those obtained by the high pressure radical polymerization method were used.

There are eight types of examples.

In Example 1, 70% by weight of ethylene / butene-1 copolymer [A1] polymerized by the above polymerization method and HP-
The composition is 30% by weight of LDPE [B1].
[A1] has a density of 0.896 g / cm ³ , MFR of 8.0 g / 10 minutes, Tm of 90 ° C., and Mw / Mn of 2.
0, SCB is 25.0 / 1000C. [B1]
Has a density of 0.920 g / cm ³ and an MFR of 3.0 g /
10 minutes, Tm is 107 ° C.

Example 2 is a mixture of the ethylene used in Example 1 /
70% by weight of butene-1 copolymer [A1] and HP-LDP
The composition is 30% by weight of E [B2]. [B
2] has a density of 0.919 g / cm ³ and an MFR of 8.0.
g / 10 min, Tm is 104 ° C.

Example 3 is a composition comprising 70% by weight of the ethylene / butene-1 copolymer [A2] polymerized by the above polymerization method and 30% by weight of HP-LDPE [B1] used in Example 1. Is. [A2] has a density of 0.912 g / c
m ³ , MFR is 2.6 g / 10 minutes, Tm is 102 ° C., M
The w / Mn is 2.2 and the SCB is 16.8 / 1000C.

Example 4 is a composition comprising 70% by weight of the ethylene / butene-1 copolymer [A3] polymerized by the above polymerization method and 30% by weight of HP-LDPE [B1] used in Example 1. Is. [A3] has a density of 0.896 g / c
m ³ , MFR 2.6 g / 10 min, Tm 90 ° C., Mw
/ Mn is 2.1 and SCB is 24.0 / 1000C.

Example 5 is a composition comprising 75% by weight of the ethylene / butene-1 copolymer [A4] polymerized by the above polymerization method and 25% by weight of HP-LDPE [B1] used in Example 1. Is. [A4] has a density of 0.900 g / c
m ³ , MFR 22.0 g / 10 minutes, Tm 96 ° C, M
The w / Mn is 2.0 and the SCB is 22.4 / 1000C.

Example 6 is the same composition as [A4] and [B1] as in Example 5, but the mixed composition is [A4].
65% by weight and [B1] 35% by weight.

Example 7 is a composition comprising 75% by weight of the ethylene / hexene-1 copolymer [A5] polymerized by the above polymerization method and 25% by weight of HP-LDPE [B1] used in Example 1. Is. [A5] has a density of 0.905 g /
cm ³ , MFR 20 g / 10 minutes, Tm 95 ° C., Mw
/ Mn is 2.2 and SCB is 18.4 / 1000C.

Example 8 is the same composition as [A5] and [B1] in Example 7, but the mixed composition is [A].
5] 65% by weight and [B1] 35% by weight.

There were four types of comparative examples.

Comparative Example 1 is a composition comprising 70% by weight of the ethylene / hexene-1 copolymer [C1] polymerized by the above polymerization method and 30% by weight of [B1] used in Example 1.

[C1] has a higher melting point than [B1] and is outside the scope of the claims. [C1] has a density of 0.
923 g / cm ³ , MFR 1.8 g / 10 min, Tm 114 ° C., Mw / Mn 1.8, SCB 8.3 / 10
00C.

Comparative Example 2 is an ethylene / butene-1 copolymer [D1] 7 polymerized with a conventionally known Ziegler type catalyst.
0 wt% and HP-LDPE [B1] 3 used in Example 1
The composition is 0% by weight. [D1] has a density of 0.910 g / cm ³ , MFR of 2.0 g / 10 min, and T
m is 102 ° C, Mw / Mn is 4.2, SCB is 21.4
/ 1000C.

Comparative Example 3 is an ethylene / butene-1 copolymer [D2] 7 polymerized with a conventionally known Ziegler type catalyst.
0 wt% and HP-LDPE [B1] 3 used in Example 1
The composition is 0% by weight. [D2] has a density of 0.900 g / cm ³ , MFR of 1.9 g / 10 minutes, and T
m is 102 ° C., Mw / Mn is 4.2, SCB is 29.1.
/ 1000C.

Comparative Example 4 is 75% by weight of ethylene / hexene-1 copolymer [D3] polymerized with a Ziegler type catalyst.
And 25% by weight of HP-LDPE [B1] used in Example 1.
And a composition comprising [D3] has a density of 0.91
0 g / cm ³ , MFR 18.0 g / 10 minutes, Tm 1
02 ° C, Mw / Mn 4.1, SCB 23.6 / 10
00C.

The compositions used in the examples and comparative examples were obtained by mixing the mixed components in an appropriate composition and adding 1000 ppm of a phenolic antioxidant Irganox 1076 as an antioxidant and 100 ppm of a phosphorus antioxidant P-EPQ.
It was obtained by adding 0 ppm and melt granulating with a single-screw extruder. A Labo Plastomill manufactured by Toyo Seiki Co., Ltd. was used for the melt granulation.

Various physical properties of the above-mentioned granulated products used in Examples and Comparative Examples were measured by the following methods.

MFR: Melt flow rate (MFR)
Is 190 ° C., 216 according to ASTM D-1238.
It was measured under a load of 0 g.

Melting point: The melting point was measured using a differential scanning calorimeter [DSC-7, manufactured by Perkin Elmer Co., Ltd.].
After melting the sample at 200 ° C for 5 minutes in the device, 10 ° C
Cooled down to 30 ℃ at 10 ℃ / minute, again at 10 ℃ /
The temperature at the maximum peak position of the endothermic curve obtained when the temperature was raised in minutes was taken as the melting point.

Density: 1 according to JIS K6760
The density of what was left to cool at room temperature after being immersed in hot water at 00 ° C for 1 hour was measured by a density gradient tube kept at 23 ° C.

Short chain branching number (SCB): The number of short chain branching (SCB) in the molecular chain was determined by using Fourier transform infrared absorption spectrometer [FT-IR spectrometer 1760X manufactured by Perkin Elmer Co., Ltd.]. , 1378 cm ^−1, and the intensity of the absorption band corresponding to the bending vibration of the methyl group.

Heat-sealing strength: Regarding the heat-sealing strength of the compositions used in Examples and Comparative Examples, a thickness of 1 prepared by using a compression molding machine (manufactured by Kansai Roll Co., Ltd.)
It was measured using a press sheet of 00 μm. A heat sealer (manufactured by Tester Sangyo Co., Ltd.) is used for heat sealing, and a sealing pressure of 2 kgf is applied to an area of 15 mm × 10 mm.
/ Cm ³ and seal time 5.0 seconds. Regarding the peeling strength of the seal portion, a tensile tester (manufactured by Orientec Co., Ltd.) was used, and a chuck distance of 40 m
It was evaluated by the load when the seal portion was pulled by peeling at m and a pulling speed of 300 mm / min. These are JIS Z170
According to 7.

Table 1 shows the characteristics of the ethylene / α-olefin copolymers and HP-LDPE in Examples 1 to 8 and the melting points of the HP-LDPE components in these compositions.

[0061]

[Table 1]

Table 2 shows the characteristics of the ethylene / α-olefin copolymers and HP-LDPE in Comparative Examples 1 to 4 and the melting points of the HP-LDPE components in these compositions.

[0063]

[Table 2]

Table 3 shows the relationship between heat seal temperature and heat seal strength in Examples 1, 2, 5, and 7 as a representative of Examples 1 to 8.

[0065]

[Table 3]

Further, as a representative of Comparative Examples 1 to 4, Comparative Example 1
Table 4 shows the relationship between the heat seal temperature and the heat seal strength, and Table 5 shows the relationship between the heat seal temperature and the heat seal strength of Comparative Example 4.

[0067]

[Table 4]

[0068]

[Table 5]

[0069]

The polyethylene resin composition of the present invention has, in addition to the conventionally known characteristics such as processability and heat seal strength,
It can be heat-sealed at a higher speed, that is, at a lower temperature, and is suitable as a heat-sealing material in an extrusion laminate material.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between heat seal temperature and heat seal strength in Examples 1, 2, 5, and 7 and Comparative Examples 1 and 4.

Claims (1)

[Claims] 1. A density of (a) 0.880 to 0.920 g /
in the range of cm ^3, is (b) 190 ℃, melt flow rate measured under a load of 2160 g (MFR) 1.0
˜50 g / 10 min, (c) the weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) is 3 or less, and (d) in the differential scanning calorimeter,
The temperature at the maximum peak position (Tm (° C)) and infrared of the endothermic curve obtained when melting at 0 ° C for 5 minutes and then cooling at 10 ° C / minute to 30 ° C and raising the temperature again at 10 ° C / minute 1000 carbon atoms determined from absorption spectrum measurement
The number of short chain branches (SCB) per unit satisfies the relationship represented by the formula (1), and Tm <−1.8 × SCB + 138 (1) (e) Tm (° C.) is obtained by the following high pressure radical polymerization method. And a copolymer of ethylene and an α-olefin having a carbon number of 3 or more (hereinafter, referred to as [A]), which has a lower temperature than the low density polyethylene used, and (f) has a density of 0.910 to 0.935 g / c.
m ³ and the melt flow rate (MFR) measured under a load of (g) 190 ° C. and 2160 g is 1.0 to
It is composed of low-density polyethylene (hereinafter referred to as [B]) obtained by a high-pressure radical polymerization method of 20 g / 10 minutes,
(H) [A] / [B] weight ratio is 90/10 to 60/40
A polyethylene resin composition comprising: