JP2002206008A - Polyethylene-based resin for forming inflation film and inflation film using the same as base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene resin giving an inflation film having excellent balance in physical properties such as shock resistance and little in one- sided wall thickness, and an inflation film having excellent balance in the physical properties produced by using the resin as a base material. SOLUTION: The polyethylene resin for forming an inflation film has a soluble-material ratio in boiling hexane of ⊖1.5 mass % and a polydispersibility index of 30-60 at 190 deg.C, and satisfies at least one out of the features that the rate of change of peak rations in the molecular weight distribution before and after granulation is >=10%, and that the peak ratio in the molecular weight distribution before granulation is <=0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin for forming an inflation film and an inflation film using the same, and more particularly to an inflation film having an excellent balance of physical properties such as impact resistance and low thickness unevenness. The present invention relates to a polyethylene-based resin and an inflation film using the same as a base material and having an excellent balance of physical properties.

[0002]

2. Description of the Related Art Polyethylene resins are widely used in various fields as general-purpose resins, and one of their typical uses is for films. Various methods are known as a method for producing this film, and among them, the inflation molding method is widely used industrially.

The inflation molding method is a method in which a polyethylene resin is extruded into a tube from a tubular die in a molten state, solidified by air cooling while being expanded by an internal pressure, and continuously wound up. In order to ensure high productivity, further high speed is required, and the resulting film is required to have excellent impact resistance and low thickness unevenness.

However, when high-speed molding is performed, the spiral flow of the resin inside the die appears as it is in the flow from the exit portion of the die slip, that is, a so-called spiral mark is generated. The flow rate of the resin differs between the other portions, and this appears as uneven thickness of the film. As a result, wrinkles and sagging occur in the raw film of the film, resulting in problems of printability and slitting properties in the secondary processing of the film, deterioration of the film, reduction of the bag making speed during film making, and heat sealing. Problems such as defects occur.

In order to solve such a problem, conventionally,
Various countermeasures have been taken from the molding surface, such as using a rotary die, increasing the efficiency of bubble cooling by the internal cooling method, and reducing the die slip, but none of them can provide sufficiently satisfactory film properties. This is the actual situation. Also, in order to improve the balance between uneven thickness and impact resistance,
It has been proposed to control the polydispersity index, the sliding speed, the melt viscosity and the like within a predetermined range (JP-A-11-7142).
No. 7), however, the low thickness unevenness characteristics of the film were not sufficiently satisfied.

[0006]

SUMMARY OF THE INVENTION The present invention provides a polyethylene resin which gives an inflation film having an excellent balance of physical properties such as impact resistance and low thickness unevenness under such circumstances, and a base material comprising the same. It is an object of the present invention to provide an inflation film excellent in the above balance of physical properties.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, (1) the boiling hexane soluble fraction is not more than a specific value and the polydispersity index is Polyethylene resin having a predetermined range and a rate of change in the peak ratio of the molecular weight distribution before and after granulation is a specific value or more, or (2) a boiling hexane soluble fraction is a specific value or less, and polydispersion. A polyethylene resin having an index in a predetermined range and a peak ratio of a molecular weight distribution before granulation being equal to or less than a specific value gives an inflation film excellent in physical property balance (impact resistance and low uneven thickness). Have been found, and are suitable for use in blown film molding. The present invention has been completed based on such findings.

That is, in the first invention of the present invention, the soluble fraction in boiling hexane is 1.5% by mass or less, and the temperature is 1%.
A polydispersity index at 90 ° C. in the range of 32 to 60,
And the rate of change of the peak ratio of the molecular weight distribution before and after granulation is 10
% Or more, and a polyethylene resin for blown film molding. Further, the second invention of the present invention is characterized in that the soluble fraction in boiling hexane is 1.5% by mass or less, the polydispersity index at a temperature of 190 ° C is in the range of 32 to 60, and the molecular weight distribution before granulation. And a peak ratio of 0.8 or less. Further, the present invention also provides an inflation film using the above-mentioned polyethylene resin as a base material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene resin for forming a blown film of the present invention has the following physical properties. In the polyethylene resin for forming a blown film of the present invention, the soluble fraction in boiling hexane needs to be 1.5% by mass or less,
Preferably it is 1% by mass or less. When the soluble fraction exceeds 1.5% by mass, the impact resistance of the obtained film decreases. This soluble fraction is a value measured by the following method. That is, polyethylene pellets are crushed by a crusher equipped with a rotary cutter or the like until the maximum length becomes 2 mm or less. Using about 3 g of the obtained pulverized product, about once /
Adjust Soxhlet extraction with boiling hexane for 6 minutes while adjusting the reflux time so that the siphon phenomenon occurs at a rate of 1 minute.
Perform for hours. After the extraction is completed, the remaining polyethylene is heated to 70 ° C.
, And then cooled to room temperature and weighed. Before extraction and the weight of the crushed polyethylene after extracting the W ₁ and W _{2, respectively, (W 1 -W 2) /} W 1 × 10
The value of 0 was regarded as the boiling hexane soluble fraction (% by mass).

Next, the temperature of the polyethylene resin is 190 ° C.
(Hereinafter sometimes abbreviated as PDI) must be in the range of 32 to 60. If this PDI is less than 32, the uneven thickness in the film is not sufficiently reduced. On the other hand, if it exceeds 60, the impact resistance is greatly reduced. This PDI is preferably in the range of 32 to 50 from the viewpoint of the balance between the film formability and impact strength.

Note that this PDI is a value measured by the following method. That is, a resin is sandwiched between two parallel flat plates at a temperature of 190 ° C. to give dynamic strain, and the relationship between the frequency of the dynamic strain and the storage elastic modulus is examined. Storage modulus G '=
The frequency giving 3.0 × 10 ³ Pa is ω ₁ (sec ⁻¹ ),
The frequency giving G '= 1.0 × 10 ⁵ Pa is ω ₂ (sec
^-1 ), the polydispersity index PDI is defined as ω ₂ / 10ω ₁ . In the present invention, Rheometric A
The polydispersity index PDI was determined using RES.

In the polyethylene resin of the present invention,
In addition to the above physical properties, the rate of change of the peak ratio of the molecular weight distribution before and after granulation is 10% or more (first invention), or the peak ratio of the molecular weight distribution before granulation is 0.8 or less ( The second invention) is necessary. If neither of these requirements is met, a sufficient reduction in thickness of the film cannot be expected.
Further, when both requirements are satisfied, a more excellent wall thickness improvement effect is exhibited. The rate of change of the peak ratio of the molecular weight distribution before and after granulation is preferably 12% or more. Also,
The peak ratio of the molecular weight distribution before granulation is preferably 0.78 or less. The peak ratio of the molecular weight distribution is a value measured under the following conditions by gel permeation chromatography (GPC).

GPC Measurement Conditions High Temperature GPC: Waters 150 CV + GPC Column: Shodex UT-806M (2) Solvent: 1,2,4-trichlorobenzene Temperature: 145 ° C. Flow Rate: 1.0 ml / min Calibration Curve: Universal Calibration Detector: RI (Waters 150C) Sample concentration: 0.2% (W / V) Data analysis: Using GPC-PRO software (Ver. 3.12) of VISCOTEK

How to determine the peak ratio of the molecular weight distribution The differential distribution value (dw /
the maximum value of the dlogM) and H _1, logM is 5.0 to 6.
The maximum value of the differential distribution value (dw / dlogM) between 0 is defined as H _2, and the peak ratio of the molecular weight distribution is defined as H ₂ / H ₁ . “Log” is a common logarithm, and M is a molecular weight. Further, the rate of change ΔPR of the ratio of the molecular weight distribution peaks before and after granulation is defined as follows. ΔPR (%) = [(PR ₁ −PR ₀ ) / PR ₀ ] × 10
0, where PR ₀ : peak ratio of molecular weight distribution before granulation (powder) PR ₁ : peak ratio of molecular weight distribution after granulation (pellet)

Further, in the polyethylene resin for forming a blown film of the first invention and the second invention,
The melt index (MI) is preferably in the range of 0.01 to 5.0 g / 10 minutes. This MI is 0.01 g / 1
If the time is less than 0 minutes, the extrusion characteristics are poor, and when inflation molding is performed, melt fracture is likely to occur, and it is difficult to obtain a good film. On the other hand, if the MI exceeds 5.0 g / 10 minutes, the melt tension of the resin decreases, and the stability of bubbles during inflation molding may decrease. From the viewpoint of the balance between the extrusion characteristics and the melt tension, the preferable MI is in the range of 0.02 to 3.0 g / 10 minutes, particularly 0.0.
A range of 3 to 2.0 / 10 minutes is preferred. Note that this MI
Is a value measured in accordance with JIS K7210 at a temperature of 190 ° C. and a load of 21.18 N.

Further, in the polyethylene resin for forming a blown film of the first invention and the second invention,
Density is preferably in the range of 0.900~0.970g / cm ^3. If the density is less than 0.900 g / cm ³ , the stiffness of the film may be weak, and 0.970 g / cm ³
If it exceeds cm ³ , the impact strength of the film tends to be insufficient. From the viewpoint of the balance between the stiffness of the film and the impact resistance, a more preferable range of the density is 0.93.
0 to 0.965 g / cm ³ , with a particularly preferred range being 0.95 g / cm ³ .
935-0.960 g / cm ³ . The density is a value measured according to JIS K7112.

The ethylene polymer which is a base polymer of the polyethylene resin for forming an inflation film of the first and second inventions may be any one which can provide a polyethylene resin having the above-mentioned properties. Well, the type is not particularly limited. Examples of the ethylene-based polymer include a homopolymer of ethylene and ethylene and another α-olefin such as propylene;
1; pentene-1; octene-1; 4-methylpentene-1; a copolymer with vinylcyclohexane and the like. In addition, other α- copolymerized with ethylene
One type of olefin may be used, or two or more types may be used in combination.

The method for producing such an ethylene polymer is not particularly limited. For example, (1) a Ziegler-type catalyst comprising a transition metal component such as titanium or vanadium and an organoaluminum compound; Philips type catalyst used, (3) zirconium, titanium,
The polymerization may be carried out in the presence of a polymerization catalyst appropriately selected from metallocene catalysts and the like comprising a transition metal compound such as hafnium and a cocatalyst such as an aluminoxane or an ionizing agent. As a polymerization method, for example, a solution polymerization method, a slurry polymerization method, a gas phase polymerization method, or the like can be used.

Specifically, a solid catalyst component containing magnesium, titanium, and halogen, and a so-called supported Ziegler catalyst mainly containing organoaluminum are used.
It is preferable to use an ethylene-based polymer obtained by a multistage polymerization method in which polymerization is further performed in the second reaction zone in the presence of a reaction product obtained by performing polymerization in the first reaction zone. Particularly, in the first stage, ethylene is homopolymerized, in the second stage, ethylene and another α-olefin are copolymerized, and the molecular weight of the polymer in the first stage is reduced by the copolymerization in the second stage. Ethylene polymers obtained by polymerization under such conditions as to lower the molecular weight of the coalesced are preferably used.

The method for granulating the polyethylene resin for forming a blown film of the first and second inventions having the above-mentioned properties is not particularly limited, and various methods can be used. For example, preferable examples include a method of operating the extruder while reducing the charge amount of the ethylene-based polymer and a method of operating the extruder at a high rotation speed and granulating. Preferred charge amount and rotation speed are
Since it depends on the type of extruder, it cannot be specified unconditionally. However, if the charge amount is too large or the number of rotations is too low, the constitutional requirements of the first invention of the present invention may not be satisfied. Even in the preferred embodiment described above, if the rotation speed is too high, the ethylene-based polymer may be deteriorated and the impact resistance may be reduced.

In this way, a polyethylene resin for forming a blown film is prepared. In the first invention and the second invention of the present invention, various known additives such as, for example, Stabilizers against oxidative deterioration, heat deterioration, and light deterioration (phenol-based stabilizers, organic phosphite-based stabilizers, thioether-based stabilizers, hindered amine-based stabilizers), ultraviolet absorbers (benzotriazole-based, benzophenone-based), neutralizers (Metal soap, hydrotalcite-based), antistatic agent (cationic, anionic, nonionic, etc.),
Anti-blocking agent (diatomaceous earth, synthetic silica), flame retardant (aluminum hydrate, gypsum hydrate),
Inorganic fillers (spherical fillers, plate-like fillers, fibrous fillers), organic fillers (wood particles, fir-shell powder), and colorants can be added as appropriate.

As described above, examples of the inorganic filler include a spherical filler, a plate-like filler, and a fibrous filler. Examples of the spherical filler include calcium carbonate,
Kaolin (aluminum silicate), silica, perlite, shirasu balloon, sericite, diatomaceous earth, calcium sulfite, calcined alumina, calcium silicate, crystalline zeolite, amorphous zeolite, and the like. Mica and the like, as the fibrous filler, for example, needle-like things like wollastonite, magnesium oxysulfate, potassium titanate fiber, fibrous things like fibrous calcium carbonate,
Further, a completely fibrous material such as glass fiber may be used.

On the other hand, examples of the organic filler include wood particles such as wood powder and cotton powder, fir hull powder, crosslinked rubber powder, plastic powder, collagen powder and the like. Examples of the flame retardant include aluminum hydrate, gypsum, zinc borate, barium borate, borax, kaolin, clay, calcium carbonate, alunite, basic magnesium carbonate, calcium hydroxide, and magnesium hydroxide. No.

As the above-mentioned various stabilizers, use of a stabilizer against oxidative deterioration, heat deterioration and the like is most common. For example, phenol-based stabilizers, organic phosphite-based stabilizers,
A thioether-based stabilizer, a hindered amine-based stabilizer and the like can be used. As phenolic stabilizers,
Conventionally known, for example, 2,6-di-t-butyl-4
-Methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl -4-Methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t
-Butylphenol, 2-t-butyl-2-ethyl-6
-T-octylphenol, 2-isobutyl-4-ethyl-5-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, styrenated mixed cresol, dl-α-tocopherol, t
-Butylhydroquinone, 2,2'-methylenebis (4-
Methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 2,2'- Thiobis (4-methyl-6
-T-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-
Cresol], 2,2'-ethylidenebis (4,6-di-t-butylphenol), 2,2'-butylidenebis (2-t-butyl-4-methylphenol), 1,1,1
3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1, 6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2'-thiodiethylenebis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4
-Hydroxybenzylphosphonate-diethyl ester, 1,3,5-tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate,
1,3,5-tris [(3,5-di-t-butyl-4-
Hydroxyphenyl) propionyloxyethyl] isocyanurate, tris (4-tert-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate,
2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5
-Triazine, tetrakis [methylene-3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate] methane, bis (3,5-di-tert-butyl-4-hydroxybenzylphosphonate) calcium, bis (3,5-di-tert-butyl-4) -Hydroxybenzylphosphonate) nickel, bis [3,3-bis (3-
t-butyl-4-hydroxyphenyl) butyric acid] glycol ester, N, N'-bis [3- (3
5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 2,2'-oxamidobis [ethyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], bis [2 -T-butyl-4
-Methyl-6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) phenyl] terephthalate, 1,
3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene,
3,9-bis [1,1-dimethyl-2- [β- (3-t
-Butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 2,2-bis [4
-[2- (3,5-di-t-butyl-4-hydroxyhydrocinnamoyloxy)] ethoxyphenyl] propane and stearyl-β- (4-hydroxy-3,5-di-t-butylphenol) propionate Β-
(3,5-di-t-butyl-4-hydroxyphenyl)
And alkyl propionate. Among these, 2,6-di-t-butyl-4-methylphenol, stearyl-β- (4-hydroxy-3,5-
Di-t-butylphenol) propionate, 2,2 '
-Ethylidenebis (4,6-di-tert-butylphenol) and tetrakis [methylene-3- (3,5-di-tert-butylphenol)
-Butyl-4-hydroxyphenyl) propionate]
Methane is preferred.

Examples of the organic phosphite-based stabilizer include, for example, trioctyl phosphite, trilauryl phosphite, tristridecyl phosphite, tris isodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, Phenyldi (tridecyl) phosphite, diphenylisooctylphosphite, diphenylisodecylphosphite, diphenyltridecylphosphite, triphenylphosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) ) Phosphite, tris (butoxyethyl) phosphite, tetratridecyl-4,4'-butylidenebis (3-methyl-6-tert-butylphenol) -diphosphite, 4,
4'-isopropylidene-diphenol alkyl phosphite (where alkyl has about 12 to 15 carbon atoms),
4,4'-isopropylidenebis (2-t-butylphenol) di (nonylphenyl) phosphite, tris (biphenyl) phosphite, tetra (tridecyl)-
1,1,3-tris (2-methyl-5-t-butyl-4
-Hydroxyphenyl) butane diphosphite, tris (3,5-di-t-butyl-4-hydroxyphenyl)
Phosphite, hydrogenated-4,4'-isopropylidene diphenol polyphosphite, bis (octylphenyl) bis [4,4'-butylidenebis (3-methyl-
6-t-butylphenol)] • 1,6-hexanediol diphosphite, hexatridecyl-1,1,3-
Tris (2-methyl-4-hydroxy-5-t-butylphenol) diphosphite, tris [4,4'-isopropylidenebis (2-t-butylphenol)] phosphite, tris (1,3-distearoyloxyisopropyl) Phosphite, 9,10-dihydro-9-phosphaphenanthrene-10-oxide, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, distearylpentaerythritol di Phosphite, di (nonylphenyl) pentaerythritol diphosphite, phenyl / 4,4'-isopropylidenediphenol / pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite , Screw (2,
6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite and phenylbisphenol-A-pentaerythritol diphosphite.

Among these, tris (2,4-di-t)
-Butylphenyl) phosphite, tris (nonylphenyl) phosphite and tetrakis (2,4-di-t-
Butylphenyl) -4,4'-biphenylenediphosphite is preferred, and tris (2,4-di-t-butylphenyl) phosphite is particularly preferred. Further, as the organic thioether-based stabilizer, it is preferable to use a polyhydric alcohol ester of dialkylthiodipropionate and alkylthiopropionic acid. As the dialkylthiodipropionate used here, the carbon number is 6 to
A dialkylthiodipropionate having an alkyl group of 20 is preferable, and a polyhydric alcohol ester of an alkylthiopropionic acid is preferably a polyhydric alcohol ester of an alkylthiopropionic acid having an alkyl group having 4 to 20 carbon atoms. In this case, examples of the polyhydric alcohol constituting the polyhydric alcohol ester include glycerin, trimethylolethane, trimethylolpropane,
Examples thereof include pentaerythritol and trishydroxyethyl isocyanurate.

Examples of such dialkylthiodipropionates include dilaurylthiodipropionate, dimyristylthiodipropionate and distearylthiodipropionate. On the other hand, polyhydric alcohol esters of alkylthiopropionic acid include, for example, glycerin tributylthiopropionate, glycerin trioctyl thiopropionate, glycerin trilauryl thiopropionate, glycerin tristearyl thiopropionate, trimethylolethane tributyl Thiopropionate, trimethylol ethane trioctyl thiopropionate, trimethylol ethane trilauryl thiopropionate, trimethylol ethane tristearyl thiopropionate, pentaerythritol tetrabutyl thiopropionate,
Examples thereof include pentaerythritol tetraoctylthiopropionate, pentaerythritol tetralauryl thiopropionate, and pentaerythritol tetrastearyl thiopropionate. Among these, dilauryl thiodipropionate, distearyl thiodipropionate and pentaerythritol tetralauryl thiopropionate are preferred.

Examples of hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2, succinate. 2,6,6-tetramethylpiperidine polycondensate, poly [6- (1,1,
3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [2,2 6,6-tetramethyl-4-piperidyl) imino], tetrakis (2,2,6,6-tetramethyl-
4-piperidyl) -1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis- (1,2,6,6-pentamethyl-4-piperidyl) ) -2- (3,5-di-t-
Butyl-4-hydroxybenzyl) -2-n-butylmalonate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,1′-
(1,2-ethanediyl) bis (3,3,5,5-tetramethylpiperazinone), (mixed 2,2,6,6
-Tetramethyl-4-piperidyl / tridecyl) -1,
2,3,4-butanetetracarboxylate, (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed [2 , 2,6,6-Tetramethyl-4-piperidyl / β, β, β ', β'-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] Diethyl] -1,2,3,4
-Butanetetracarboxylate, mixed [1,
2,2,6,6-pentamethyl-4-piperidyl / β,
β, β ', β'-tetramethyl-3,9- [2,4
8,10-Tetraoxaspiro (5,5) undecane]
Diethyl] -1,2,3,4-butanetetracarboxylate, N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,
2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, poly [6-N-morpholyl-1,3,5-triazine-
2,4-diyl] [(2,2,6,6-tetramethyl-
4-piperidyl) imino] hexamethylene [(2,2,
6,6-tetramethyl-4-piperidyl) imide],
N, N'-bis (2,2,6,6-tetramethyl-4-
Piperidyl) condensate of hexamethylenediamine and 1,2-dibromoethane, [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,
2,6,6-tetramethyl-4-piperidyl) imino]
Propionamide and the like can be mentioned.

Among these hindered amine-based stabilizers, in particular, polycondensate of dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate, poly [6 -(1,1,3,3-
Tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2
2,6,6-tetramethyl-4-piperidyl) imino], tetrakis (2,2,6,6-tetramethyl-4
-Piperidyl) -1,2,3,4-butanetetracarboxylate, bis (1,2,6,6-pentamethyl-4)
-Piperidyl) -2- (3,5-di-t-butyl-4-
(Hydroxybenzyl) -2-n-butylmalonate,
1,1 '-(1,2-ethanediyl) bis (3,3
5,5-tetramethylpiperazinone), (mixed 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, (mixed 1, 2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed [2,2,2
6,6-tetramethyl-4-piperidyl / β, β,
β ', β'-tetramethyl-3,9- [2,4,8,1
0-tetraoxaspiro (5,5) undecane] diethyl] -1,2,3,4-butanetetracarboxylate, mixed [1,2,2,6,6-pentamethyl-
4-piperidyl / β, β, β ', β'-tetramethyl-
3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl] -1,2,3,4-
Butanetetracarboxylate, N, N'-bis (3-
Aminopropyl) ethylenediamine-2,4-bis [N
-Butyl-N- (1,2,6,6-pentamethyl-4-
Piperidyl) amino] -6-chloro-1,3,5-triazine condensate, poly [6-N-morpholyl-1,3,5
-Triazine-2,4-diyl] [(2,2,6,6-
Tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imide], N, N'-bis (2,2,6,6-tetramethyl-4 -Piperidyl) hexamethylenediamine and 1,2-dibromoethane condensate, [N- (2,2,
6,6-Tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6,6-tetramethyl-4-piperidyl) imino] propionamide is preferred.

The present invention also provides an inflation film based on the polyethylene resin for forming an inflation film thus obtained. The inflation molding method is not particularly limited, and a conventionally known method can be used. The molding conditions include a temperature of 160 to 340 ° C. and a blow-up ratio of 1.1 to 6.0.
Is preferable. If this temperature is less than 160 ° C., the polyethylene resin may not be sufficiently melted,
If the temperature exceeds 340 ° C., the resin may be deteriorated, and the quality of the film may be deteriorated. On the other hand, when the blow-up ratio is less than 1.1 or more than 6.0, it is difficult to obtain a high-quality film with good vertical and horizontal balance. The thickness of the blown film thus obtained is usually 5 to 100 μm.
m, preferably in the range of 10 to 60 μm.

[0031]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 (1) Polymerization Method Preparation of Catalyst Component Preparation of Solid Material Glass Reactor with Stirrer (Internal Volume
0.5 liters) was sufficiently replaced with nitrogen gas, and then 8 g of metallic magnesium, 121 g of ethanol and 0.1 g of iodine.
Was added thereto, and the mixture was reacted with stirring under reflux conditions until hydrogen gas was no longer generated from the inside of the system to obtain a solid product.
The reaction solution containing the solid product was dried under reduced pressure to obtain 25 g of the solid product, 200 ml of hexane and a stainless steel ball mill (internal volume 400 ml, 100 stainless steel balls having a diameter of 1.2 cm).
And crushed for 10 hours. After distilling off hexane under reduced pressure, the particle size of the obtained solid substance was measured by the above-mentioned measuring method. μm, maximum particle size μm. Preparation of solid catalyst component 15 g of the solid substance obtained above and 350 ml of dehydrated hexane were added to a glass three-necked flask (internal volume 0.5 liter) sufficiently purged with nitrogen gas, and silicon tetrachloride was stirred under stirring. Add 3.8 ml of ethanol and 3.8 ml of ethanol, and add
A time reaction was performed. Next, 20 ml of titanium tetrachloride was added and reacted at 70 ° C. for 6 hours, followed by washing with hexane to obtain a solid catalyst component. 1 g of this solid catalyst component
When the titanium content per was measured by a colorimetric method, it was 4
It was 4 mg.

Method for producing ethylene / α-olefin polymer
The first stage polymerization was carried out as follows. That is, ethylene was added to a polymerization apparatus having a stirrer having an internal volume of 200 liters.
6.0 kg / h, hexane 17 l / h, hydrogen 100
Liter / hour, and the above solid catalyst component was 0.9 mmol / hour in terms of titanium atom.
Triethylaluminum was introduced at a rate of 2.4 mmol / h and diethylaluminum chloride at a rate of 27.3 mmol / h. A polymerization temperature of 80 ° C. and a polymerization pressure (total pressure) of 0.41
The reaction was continuously performed under the conditions of MPaG and a residence time of 3.5 hours. The obtained suspension solution of hexane containing polyethylene was led to a hydrogen degassing tank at the same temperature (80 ° C.) to separate hydrogen, and then the whole amount was directly transferred to the next second-stage polymerization reactor (with an internal volume of 200 liters). ). In the second-stage polymerization vessel, 4.5 kg / h of ethylene and 12 liters of hexane /
Hour, butene-1 was supplied at a rate of 150 g / hour and hydrogen was supplied at a rate of 0.25 liter / hour. Continuously, an ethylene-based copolymer (ethylene-butene-1 copolymer) was obtained. The obtained hexane suspension of the ethylene copolymer is subjected to solid-liquid separation by a centrifugal separator under an atmosphere of 60 ° C. to separate a wet powder cake.
This powder cake was continuously dried in a powder dryer adjusted to 100 ° C. under the condition of a residence time of 1 hour.

(2) Granulation The polyethylene powder obtained in (1) above was blended with additives (Irgafos 168 (antioxidant, manufactured by Ciba Specialty Chemicals) and calcium stearate) in the amounts shown in Table 1. . Thereafter, the mixture was introduced into a supply hopper of a twin-screw extruder (TEX30, manufactured by Nippon Steel Works, co-rotating twin-screw extruder), and was melt-kneaded at the extruder rotation speed and charge amount shown in Table 1 (extruder). Set temperature: 200 ° C). After melt-kneading, the extruded strand was cut to obtain a columnar pellet (about 4 mm in diameter and about 2 mm in height). (3) Inflation molding The pellets obtained in the above (2) were inflation molded under the following conditions. Molding machine: Placo NLM 50 Die Model: Placo SG-11-100F6 special Lip part outer diameter: 100 mmφ Gap: 1.2 mm Land length: 20 mm Spiral part outer diameter: 110 mmφ Number of strips: 6 Discharge amount: 60 kg / h Pulling speed: 45 m / min Film folding diameter: 500 mm Film thickness: 25 μm Set temperature: 200 ° C. Blow-up ratio: 3.2

(4) The pellet obtained in (2) above
The boiling hexane soluble fraction, polydispersity index, change rate of the peak ratio of the molecular weight distribution before and after granulation, peak ratio of the molecular weight distribution before granulation, melt index and density were evaluated by the methods described above. The blown film was evaluated by the following evaluation method. Table 2 shows the results. Evaluation method of thickness deviation of film The thickness of the film was continuously measured in the circumferential direction, and the standard deviation of the data group was obtained and used as a measure of thickness deviation. Method for Evaluating Impact Strength of Film Impact strength was measured using a film impact tester (manufactured by Toyo Seiki Co., Ltd.).

Example 2 In the second stage polymerization of Example 1, 5.5 kg /
Hour, hexane 15 l / h, butene-1 110
A film was prepared and evaluated in the same manner as in Example 1 except that g / h and hydrogen were fed at 0.80 l / h. Table 2 shows the results. Example 3 Granulation was performed in the same manner as in Example 1 except that the amount of charge to the extruder and the number of revolutions of the extruder were changed to the conditions shown in Table 1 in the granulation of Example 1. In the second-stage polymerization of Example 1, the procedure was performed except that ethylene was supplied at 4.2 kg / h, hexane was supplied at 11 l / h, butene-1 was supplied at 160 g / h, and hydrogen was supplied at 0.14 l / h. A film was produced in the same manner as in Example 1, and the same evaluation was performed. Table 2 shows the results.

Comparative Example 1 A film was produced in the same manner as in Example 2 except that the granulation conditions were the same as in Example 3. Table 2 shows the evaluation results of the films. Comparative Example 2 In Example 1, the hexane suspension of the ethylene-based copolymer was replaced with a 20 ° C. atmosphere instead of a 60 ° C. atmosphere.
Solid-liquid separation was performed using a centrifugal separator, and the granulation conditions were adjusted according to Example 3.
A film was prepared in the same manner as in Example 1 except that the same was used, and the same evaluation was performed. Table 2 shows the results. Comparative Example 3 Density: 0.949 g / cm ³ , Melt Index: 0.05
Irgafos 168 (Antioxidant, Ciba.TM.) was added to a polyethylene resin powder having a polydispersity index of 26.8 g / 10 min.
Specialty Chemicals, Inc.) 1000 ppm by weight
The melt kneading of the base polymer to which 2,000 ppm by weight of calcium stearate was added was performed as follows. That is, the base polymer was melt-kneaded while introducing a gas mixture having an oxygen concentration of 10% by volume from the vent of the extruder (after melting the polyethylene resin).
Hereinafter, a film was produced in the same manner as in Example 1, and the same evaluation was performed. Table 2 shows the results.

[0037]

[Table 1]

[0038]

[Table 2]

From Table 2, it can be seen that all of the films of Examples 1 to 3 have a high impact resistance of 32 kJ / m or more, a small thickness deviation of 1.3 μm or less, and have an excellent balance of physical properties. I understand. On the contrary,
The films of Comparative Examples 1 and 3 have very high impact resistance, but have a thickness deviation of 2 μm or more and are inferior in uneven thickness characteristics. Further, the film of Comparative Example 2 has a small thickness deviation and has no problem in uneven thickness characteristics, but has a low impact strength.

[0040]

The polyethylene resin for forming a blown film according to the present invention provides a blown film having an excellent balance of physical properties such as impact resistance and low thickness unevenness.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 23:06 C08L 23:06 F term (Reference) 4F071 AA15 AA15X AA20 AA20X AA21 AA21X AA81 AA82 AA88 AH04 BA01 BB06 BB09 BC01 4F210 AA04C AG01 QA01 QK01 4J100 AA02P AA03Q AA04Q AA07Q AA17Q AA19Q AA20Q CA01 CA04 DA01 DA11 DA40 DA42 JA58

Claims (6)

[Claims] 1. A soluble fraction in boiling hexane of 1.5% by mass or less and a polydispersity index at 190 ° C. of 3
A polyethylene resin for forming a blown film, wherein the polyethylene resin is in the range of 2 to 60, and a change rate of a peak ratio of a molecular weight distribution before and after granulation is 10% or more. 2. The soluble fraction in boiling hexane is 1.5% by mass or less and the polydispersity index at 190 ° C. is 3%.
A polyethylene-based resin for forming a blown film, which is in a range of 2 to 60 and has a peak ratio of a molecular weight distribution before granulation of 0.8 or less. 3. The blown film molding according to claim 2, wherein the polyethylene resin for blown film molding further satisfies that the rate of change of the peak ratio of the molecular weight distribution before and after granulation is 10% or more. For polyethylene resin. 4. A melt index of 0.01 to 5.0 g /
The polyethylene resin for forming a blown film according to any one of claims 1 to 3, which is 10 minutes. 5. The polyethylene resin for forming a blown film according to claim 1, which has a density of 0.900 to 0.970 g / cm ³ . 6. An inflation film comprising the polyethylene resin according to claim 1 as a base material.