JP2012051119A - Heat shrinkable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat shrinkable film which has heat shrinking property, and additionally has adhesion, and is hard to be blocked.SOLUTION: The heat shrinkable film comprises: a layer 1 including a polyethylene resin (A) satisfying all of the following requirements (a1), (a2) and (a3); and a layer 2 including a polyethylene resin (B) satisfying all of the following requirements (b1), (b2) and (b3): the requirement (a1): Nis ≥0.01 per 1,000 carbon atoms, and also, Nis <0.1 per 1,000 carbon atoms; the requirement (a2): Ea is ≥40 kJ/mol; the requirement (a3): density is ≥920 kg/m; the requirement (b1): Nis ≥0.01 per 1,000 carbon atoms, and also, Nis <0.1 per 1,000 carbon atoms; the requirement (b2): Ea is ≥40 kJ/mol; and the requirement (b3): density is 900 to 915 kg/m.

Description

  The present invention relates to a heat shrinkable film. More specifically, the present invention relates to a heat-shrinkable film having adhesiveness and not easily blocking in addition to heat-shrinkability.

  The heat-shrinkable film is used for various products in various fields such as a packaging material for bundling and fixing a plurality of products as packaging objects, a label for a PET bottle, and the like. In general, the characteristics of a heat-shrinkable film include that the film heat-shrinks when heated at a temperature lower than or near the melting point of the film, a wide range of heating temperature conditions for heat-shrinking, It is required that the shrinkable film has high mechanical strength, that the film shrinks uniformly, and that the heat-shrinkable film has a good appearance after being heat shrink-wrapped. For example, Patent Document 1 describes a heat-shrinkable film using an ethylene-α-olefin copolymer for the purpose of improving heat shrinkability, mechanical strength, and appearance after heat shrinkage.

JP 2004-99680 A

  Among the applications where heat-shrinkable films are used, in addition to heat-shrinkability, the film after shrinkage adheres to the surface of the package, and adhesiveness is applied so that the film does not slip or wrinkle with a small amount of external force. May be required. Under such circumstances, an object of the present invention is to provide a heat-shrinkable film that has adhesiveness and is difficult to block in addition to heat-shrinkability.

That is, the present invention includes a layer 1 containing a polyethylene resin (A) that satisfies all of the following requirements (a1), (a2), and (a3), and the following requirements (b1), (b2), and (b3): It is a heat-shrinkable film having a layer 2 containing a polyethylene resin (B) that satisfies all.
(A1): The number of branches having 6 or more carbon atoms (N _LCB ) measured by ¹³ C-NMR is 0.01 or more per 1000 carbon atoms, and the number of branches having 5 carbon atoms (N _C5 ) is Less than 0.1 per 1000 carbon atoms (a2): Flow activation energy (Ea) is 40 kJ / mol or more (a3): Density is 920 kg / m ³ or more (b1): ^The number of branches having 6 or more carbon atoms (N _LCB ) measured by ¹³ C-NMR is 0.01 or more per 1000 carbon atoms, and the number of branches having 5 carbon atoms (N _C5 ) is 1000 carbon atoms. (B2): the flow activation energy (Ea) is 40 kJ / mol or more (b3): the density is 900 to 915 kg / m ³

  The heat-shrinkable film of the present invention has adhesiveness in addition to heat-shrinkability and is difficult to block.

  The polyethylene resin (A) and the polyethylene resin (B) are polymers having a monomer unit based on ethylene as a main unit, and are produced by a high pressure radical polymerization method. An ethylene-α-olefin copolymer produced by the above method. The polyethylene resin (A) and / or the polyethylene resin (B) is preferably an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer is an ethylene-α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms, and is a monomer unit based on ethylene and carbon. It is a copolymer having a monomer unit based on an α-olefin having 3 to 20 atoms. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4 -Methyl-1-pentene, 4-methyl-1-hexene and the like are mentioned, and 1-hexene and 1-octene are preferable. Moreover, said C3-C20 alpha olefin may be used independently and may use 2 or more types together.

  Examples of the ethylene-α-olefin copolymer include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-1-octene copolymer, and an ethylene-1 -Butene-1-hexene copolymer, ethylene-1-butene-1-octene copolymer and the like, preferably ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1 -Butene-1-hexene copolymer and ethylene-1-butene-1-octene copolymer.

The polyethylene-based resin (A) and the polyethylene-based resin (B) have a carbon atom number of 6 or more branches (hereinafter sometimes referred to as “N _LCB ”) measured by ¹³ C-NMR. The number of carbon atoms is 0.01 or more per 1000 atoms, and the number of branches having 5 carbon atoms (hereinafter sometimes referred to as “N _C5 ”) is less than 0.1 per 1000 carbon atoms. When N _LCB is 0.01 or more, the heat shrinkability is good. N _LCB is preferably at least 0.1 per 1000 carbon atoms. Further, when N _LCB and N _C5 satisfy the above values, the mechanical strength increases. From the viewpoint of increasing mechanical strength, N _LCB is preferably 1 or less per 1000 carbon atoms, and more preferably 0.7 or less. N _C5 is preferably less than 0.05 per 1000 carbon atoms, more preferably less than 0.01 and most preferably zero.

N _LCB and N _C5 of the polyethylene resin (A) and the polyethylene resin (B) are used for selection of a production method such as gas phase polymerization and slurry polymerization, selection of a polymerization catalyst, polymerization temperature, polymerization pressure, type of comonomer, and the like. It can adjust with polymerization conditions, such as addition amount.

N _LCB can be obtained by the following method. The peak of a peak having a peak top in the vicinity of 38.09 to 38.27 ppm from a ¹³ C-NMR spectrum obtained by applying an exponential to the window function, where the sum of all peak areas observed at 5 to 50 ppm is 1000 Let the area be A. This A is a value corresponding to the number of branched methine carbons having 4 or more carbon atoms. In the ¹³ C-NMR spectrum in which Gaussian was applied to the window function in order to separate the peaks of branched methine carbon having 5 or less carbon atoms and branched methine carbon having 6 or more carbon atoms, The peak area of the peak observed at 38.27 ppm is B, and the peak area of the peak observed at 38.21 to 38.09 ppm is C. And _NLCB was _{calculated |} required from the following formula _| equation.
N _LCB = A × B / (B + C)
N _C5 can be obtained by the following method. In a ¹³ C-NMR spectrum in which an exponential is applied to the window function, the sum of all peaks observed at 5 to 50 ppm is 1000, and the peak area of a peak having a peak top near 32.5 to 32.7 ppm Asked. The peak area is a value corresponding to the number of branched methylene carbons having 5 carbon atoms (C ^** in the following structural formula).
・ ・ ・ ・ CH ₂ -CH-CH ₂ -...
└CH ₂ -CH ₂ -C ^** H ₂ -CH ₂ -CH ₃
In addition, since the position of the peak derived from the methine carbon to which a branch having 5 or more carbon atoms is bonded may be shifted depending on the measurement apparatus and measurement conditions, the standard is usually measured for each measurement apparatus and measurement conditions. Go and decide. In the spectrum analysis, it is preferable to use a negative exponential function as the window function.

  From the viewpoint of heat shrinkability, the flow activation energy (Ea) of the polyethylene resin (A) and the polyethylene resin (B) is 40 kJ / mol or more, preferably 50 kJ / mol or more, more preferably It is 55 kJ / mol or more, more preferably 60 kJ / mol or more. From the viewpoint of mechanical strength, Ea is preferably 100 kJ / mol or less, and more preferably 90 kJ / mol or less.

The flow activation energy (Ea) is a master curve showing the dependence of the melt complex viscosity (unit: Pa · second) at 190 ° C. on the angular frequency (unit: rad / second) based on the temperature-time superposition principle. Is a numerical value calculated by the Arrhenius equation from the shift factor (a _T ) at the time of creating the value, and is a value obtained by the following method. That is, the melt complex viscosity-angular frequency curve of the ethylene-α-olefin copolymer at temperatures of 130 ° C., 150 ° C., 170 ° C. and 190 ° C. (T, unit: ° C.) The unit of the angular frequency is rad / sec.), Based on the temperature-time superposition principle, for each melt complex viscosity-angular frequency curve at each temperature (T), The shift factor (a _T ) at each temperature (T) obtained when superposed on the melt complex viscosity-angular frequency curve of the coalescence is obtained, and each temperature (T) and the shift factor at each temperature ( _T ) are obtained. From (a _T ), a first-order approximate expression (formula (I) below) of [ln (a _T )] and [1 / (T + 273.16)] is calculated by the method of least squares. Next, Ea is obtained from the slope m of the linear expression and the following expression (II).
ln (a _T ) = m (1 / (T + 273.16)) + n (I)
Ea = | 0.008314 × m | (II)
a _T : Shift factor Ea: Activation energy of flow (unit: kJ / mol)
T: Temperature (unit: ° C)
For the calculation, commercially available calculation software may be used. As the calculation software, Rheos V. manufactured by Rheometrics is used. 4.4.4.
The shift factor (a _T ) is obtained by moving the logarithmic curve of the melt complex viscosity-angular frequency at each temperature (T) in the log (Y) = − log (X) axis direction (however, the Y axis Is the complex viscosity of the melt, and the X axis is the angular frequency.), And the amount of movement when superposed on the melt complex viscosity-angular frequency curve at 190 ° C., in the superposition, melting at each temperature (T) The logarithmic curve of complex viscosity-angular frequency shifts the angular frequency by a _T times and the melt complex viscosity by 1 / a _T times for each curve. Moreover, the correlation coefficient when calculating | requiring (I) Formula by the least squares method from the value of four points | pieces, 130 degreeC, 150 degreeC, 170 degreeC, and 190 degreeC is usually 0.99 or more.

  The melt complex viscosity-angular frequency curve is measured using a viscoelasticity measuring apparatus (for example, Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), and usually geometry: parallel plate, plate diameter: 25 mm, plate interval: 1. It is performed under the conditions of 5 to 2 mm, strain: 5%, angular frequency: 0.1 to 100 rad / sec. The measurement is performed in a nitrogen atmosphere, and it is preferable that an appropriate amount (for example, 1000 ppm) of an antioxidant is added to the measurement sample in advance.

The density of the polyethylene resin (A) is 920 kg / m ³ or more from the viewpoint of blocking. From the viewpoint of good heat shrinkability, it is preferably 935 kg / m ³ or less, more preferably 930 kg / m ³ or less. In addition, a density is measured in accordance with the underwater substitution method prescribed | regulated to JISK7112-1980 using the sample which annealed as described in JISK6760-1995.

  The melt flow rate (MFR) of the polyethylene resin (A) is usually 0.01 to 50 g / 10 minutes, and preferably 5 g / 10 minutes or less, more preferably 3 g, from the viewpoint of enhancing the heat shrinkability. / 10 minutes or less. The MFR of the polyethylene resin (A) and the polyethylene resin (B) of the present invention is measured under the conditions of a temperature of 190 ° C. and a load of 21.18 N by the method defined in JIS K7210-1995.

  From the viewpoint of film processability, the molecular weight distribution (Mw / Mn) of the polyethylene resin (A) is preferably 5 or more, more preferably 6 or more, and still more preferably 8 or more. From the viewpoint of the mechanical strength of the film, the molecular weight distribution of the polyethylene resin (A) is preferably 25 or less, more preferably 20 or less. The molecular weight distribution (Mw / Mn) is a value obtained by calculating a polystyrene-reduced weight average molecular weight (Mw) and number average molecular weight (Mn) by gel permeation chromatography, and dividing Mw by Mn. (Mw / Mn).

The polyethylene resin (A) preferably has a g * defined by the following formula (II) of 0.70 to 0.95.
g * = [η] / ([η] _GPC × g _SCB *) (II)
[Wherein [η] represents the intrinsic viscosity (unit: dl / g) of the polyethylene resin, and is defined by the following formula (II-I). [Η] _GPC is defined by the following formula (II-II). g _SCB * is defined by the following formula (II-III).
[Η] = 23.3 × log (ηrel) (II-I)
(In the formula, ηrel represents the relative viscosity of the polyethylene resin.)
[Η] _GPC = 0.00046 × Mv ^0.725 (II-II)
(In the formula, Mv represents the viscosity average molecular weight of the polyethylene resin.)
g _SCB * = (1-A) ^1.725 (II-III)
(In formula, A measures the content of the short chain branch in a polyethylene-type resin, and is defined by following formula (II-V).
A = ((12 * n + 2n + 1) * y) / ((1000-2y-2) * 14 + (y + 2) * 15 + y * 13) (II-V)
In the formula, n represents the number of short-chain branched carbon atoms (for example, n = 2 when butene is used as the α-olefin, n = 4 when hexene is used), and y is from NMR or infrared spectroscopy. It represents the number of short chain branches per 1000 carbon atoms required. ]]
Regarding g *, the following literature was referred to: Developments in Polymer Characterisation-4, JV. Dawkins, Ed., Applied Science, London, 1983, Chapter. I, “Characterization. Long Chain Branching in Polymers, "by Th. G. Scholte

[Η] _GPC represents the intrinsic viscosity (unit: dl / g) of a polymer that is assumed to have the same molecular weight distribution as that of the polyethylene-based resin and that the molecular chain is linear.
g _SCB * represents a contribution to g * caused by introducing a short chain branch into a polyethylene resin.
As the formula (II-II), the formula described in Journal of Polymer Science, 36, 130 (1959) pp. 287-294 by LH Tung was used.

  The relative viscosity (ηrel) of the polyethylene resin can be measured by the following method. A sample solution is prepared by dissolving 100 mg of a polyethylene-based resin at 135 ° C. in 100 ml of tetralin containing 0.5% by weight of butylhydroxytoluene (BHT) as a thermal degradation inhibitor, and the sample solution is mixed with the sample solution using an Ubbelohde viscometer. BHT is calculated from the falling time of the blank solution composed of tetralin containing only 0.5% by weight as a thermal deterioration inhibitor.

で定義され、a＝０．７２５とした。 The viscosity-average molecular weight (Mv) of the polyethylene resin is the following formula (II-IV)

And a = 0.725.

  g * is an index representing the degree of contraction of a molecule in a solution caused by long chain branching. When the amount of long chain branching per molecular chain is large, the contraction of the molecular chain increases. Get smaller. The g * of the polyethylene resin is more preferably 0.90 or less, and further preferably 0.85 or less, from the viewpoint of good heat shrinkability. From the viewpoint of improving the mechanical strength, g * of the polyethylene resin (A) is more preferably 0.75 or more.

  Particularly preferred examples of the polyethylene resin (A) include polyethylene resins described in JP-A-2008-106264.

The density of the polyethylene resin (B), in order to improve the adhesion to a surface of the wrapping material, and the 915 kg / m ³ or less, preferably 913kg / m ³ or less.

  The melt flow rate (MFR) of the polyethylene resin (B) is usually 0.1 to 10 g / 10 minutes, preferably 4 g / 10 minutes or less, from the viewpoints of processability, mechanical strength, and heat shrinkability. Preferably it is 2 g / 10 minutes or less.

  The heat-shrinkable film of the present invention is a multilayer film having a layer 1 containing the polyethylene resin (A) and a layer 2 containing the polyethylene resin (B). The heat-shrinkable film of the present invention may have a layer containing a resin different from the polyethylene resin (A) and the polyethylene resin (B) between the layer 1 and the layer 2. In that case, the layers 1 and 2 are arranged so as to be the surface layers of the heat-shrinkable film, respectively.

  The thickness of the heat-shrinkable film of the present invention is usually 20 to 200 μm, preferably 25 to 150 μm, more preferably 30 to 120 μm. The ratio of the thickness of the layer 1 to the thickness of the entire film (100%) is preferably 50% or more from the viewpoint of improving coextrusion moldability and film handling properties.

  In the heat-shrinkable film of the present invention, the layer 1 and the layer 2 may be blended with an antioxidant, an antistatic agent, other resins, etc., if necessary, and these may be used alone. Two or more kinds may be used in combination.

  Examples of the antioxidant include hindered phenol compounds and phosphorus ester compounds containing a trivalent phosphorus atom. Examples of hindered phenol compounds include 2,6-dialkylphenol derivatives and 2-alkylphenol derivatives. Examples of the phosphorus ester compound containing a trivalent phosphorus atom include phosphite compounds and phosphonite compounds. These antioxidants may be used alone or in combination of two or more. In particular, from the viewpoint of stabilizing the hue, it is preferable to use a hindered phenol compound and a phosphorus ester compound in combination. The antioxidant is preferably contained in an amount of 0.01 to 1% by weight, more preferably 0.03 to 0.5% by weight, when the weight of the heat shrinkable film is 100%.

  Examples of the lubricant include fatty acids, fatty acid amides, and fatty acid esters. Examples of fatty acids include stearic acid, oleic acid, lauric acid and the like. Examples of fatty acid amides include ricinol amide and behenamide. Examples of fatty acid esters include sorbitan esters, n-butyl stearate, glycerin esters of higher fatty acids, and the like.

  Examples of the anti-blocking agent include synthetic silica, natural silica, silicon resin, polymethyl methacrylate and the like. Examples of the synthetic silica include dry silica and wet silica. Examples of natural silica include diatomaceous earth.

  Examples of the antistatic agent include glycerin esters and sorbitan acid esters of fatty acids having 8 to 22 carbon atoms, alkyl dialkanolamides of fatty acids having 8 to 22 carbon atoms, polyethylene glycol esters, and alkyldiethanolamines. .

  Examples of the pigment include white pigment and carbon black.

  Examples of the resin other than the polyethylene resin (A) and the polyethylene resin (B) include polypropylene, polybutene, ethylene-vinyl acetate copolymer, elastomer, and polyethylene that does not satisfy any of the requirements (a1) and (a2). Based resins and the like.

  When there are a plurality of components constituting each layer, these components are mixed and / or melt-kneaded and then made into a film by the production method described later. Examples of the mixing method include a method of mixing with a tumbler blender, a Henschel mixer or the like. Examples of the melt-kneading method include a melt-kneading method using a single-screw extruder or a multi-screw extruder, and a melt-kneading method using a kneader or a Banbury mixer.

  Examples of the method for producing the heat-shrinkable film of the present invention include an inflation molding method, a T-die cast molding method, an extrusion laminate molding method, a dry laminate molding method, a wet laminate molding method, and a sand laminate molding method. Combinations may be used. Among these, it is preferable to manufacture by an inflation film forming method.

  When performing extrusion molding such as an inflation molding method or a T-die cast molding method as a film production method, the extrusion molding temperature is usually 110 to 250 ° C. From the viewpoint of improving the adhesion between the film and the packaged body, the temperature is preferably 130 ° C or higher, and more preferably 140 ° C or higher. Moreover, from a viewpoint of improving the heat shrinkability of a film, Preferably it is 240 degrees C or less, More preferably, it is 220 degrees C or less, More preferably, it is 190 degrees C or less.

  The heat-shrinkable film of the present invention may be an unstretched film, or may be a stretched film obtained by subjecting the obtained film to a stretching process such as uniaxial stretching or biaxial stretching in a subsequent step. Preferably, it is an unstretched film which does not require a lot of facilities.

  The heat shrinkable film of the present invention can be used, for example, by covering a package such as a plurality of cans, bottles, books, etc. with the heat shrinkable film of the present invention and forming a bag shape or a cylindrical shape by heat sealing or fusing sealing. After that, the heat-shrinkable film is heat-shrinked through a heating tunnel, the packaged body is bound and packaged, and the heat-shrinkable film of the present invention is similarly applied to a packaged object such as one can or bottle. The method of processing and packaging at the process of this is mentioned. Applications of the heat-shrinkable film of the present invention include a label attached to a packaged body, a packaging material for protecting the packaged body, and the like.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
The physical properties of Examples and Comparative Examples were measured according to the following methods.

(1) Melt flow rate (MFR, unit: g / 10 minutes)
According to the method prescribed | regulated to JISK7210-1995, it measured on conditions of load 21.18N and temperature 190 degreeC (PE conditions).

(2) Density (Unit: kg / m ³ )
It measured according to the method prescribed | regulated to A method among JISK7112-1980. In addition, the measurement sample piece was annealed according to the method of low density polyethylene described in JIS K6760-1995 and used for measurement.

(3) Molecular weight distribution (Mw / Mn, unit:-)
Using a gel permeation chromatograph (GPC) method, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured under the following conditions (1) to (9), and the molecular weight distribution (Mw / Mn) was determined.
Measurement condition
(1) Equipment: 150CV ALC / GPC manufactured by Waters
(2) Separation column: Shodex GPC AT-806MS manufactured by Showa Denko KK
(3) Temperature: 140 ° C
(4) Solvent: o-dichlorobenzene
(5) Elution solvent flow rate: 1.0 ml / min
(6) Sample concentration: 1 mg / ml
(7) Measurement injection volume: 400 μl
(8) Molecular weight standard substance: Standard polystyrene (manufactured by Tosoh Corporation; molecular weight = 6000000 to 500)
(9) Detector: Differential refraction

(4) Flow activation energy (Ea, unit: kJ / mol)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), melt complex viscosity-angular frequency curves were measured under the following measurement conditions at temperatures of 130 ° C., 150 ° C., 170 ° C. and 190 ° C. Next, from the obtained melt complex viscosity-angular frequency curve, Rheometrics R. The activation energy (Ea) was determined using 4.4.4.
<Measurement conditions>
Geometry: Parallel plate Plate diameter: 25mm
Plate spacing: 1.5-2mm
Strain: 5%
Angular frequency: 0.1-100 rad / sec Measurement atmosphere: Under nitrogen

(5) Melting point (Tm, unit: ° C)
About 10 mg of a test piece cut out from a sheet having a thickness of about 0.5 mm produced by hot pressing was used as a measurement sample, and measurement was performed using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer). In the measurement, the measurement sample was held at 150 ° C. for 5 minutes, then cooled to 40 ° C. at 1 ° C./minute, then held at 40 ° C. for 5 minutes, and then increased to 150 ° C. at a rate of 10 ° C./minute. Warm up. The melting point was determined from the melting peak of the melting curve obtained when the temperature was raised from 40 ° C. to 150 ° C. at a rate of 10 ° C./min.

(6) g *
g * = [η] / ([η] _GPC × g _SCB *) (II)
G * was determined by the formula (II).
[Η] was determined by the following method. First, a sample solution is prepared by dissolving 100 mg of polyethylene resin at 135 ° C. in 100 ml of tetralin containing 0.5% by weight of butylhydroxytoluene (BHT) as a thermal degradation inhibitor with a relative viscosity (ηrel) of the polyethylene resin. Then, using an Ubbelohde viscometer, the sample solution was calculated from the falling time of the blank solution made of tetralin containing only 0.5% by weight of BHT as a thermal degradation inhibitor. The calculated relative viscosity (ηrel) was substituted into the formula (II-I) to obtain [η].
[Η] _GPC was determined by the following method. The viscosity average molecular weight (Mv) was calculated from the measurement result of (3) molecular weight distribution. The calculated Mv was substituted into the formula (II-II) to obtain [η] _GPC .
g _SCB * was obtained by substituting A obtained by the formula (II-V) into the formula (II-III). In addition, the measurement and calculation of the number n of short-chain branches and the number y of short-chain branches per 1000 carbon atoms in a polyethylene resin are described in the literature (Die Makromoleculare Chemie, 177, 449 (1976) McRae, MA , Madams, WF), using characteristic absorption derived from α-olefin. The infrared absorption spectrum was measured using an infrared spectrophotometer (FT-IR7300 manufactured by JASCO Corporation).

(7) Calculation method of various branch numbers The carbon nuclear magnetic resonance spectrum ( ^13C -NMR) was measured by the carbon nuclear magnetic resonance method under the following measurement conditions, and was determined by the following calculation method.
<Measurement conditions>
Apparatus: AVANCE600 manufactured by Bruker
Measuring probe: 10 mm cryoprobe Measuring solvent: 1,2-dichlorobenzene / 1,2-dichlorobenzene-d4
= 75/25 (volume ratio) mixed liquid Measurement temperature: 130 ° C
Measurement method: proton decoupling method Pulse width: 45 degrees Pulse repetition time: 4 seconds Measurement standard: Tetramethylsilane Window function: Exponential or Gaussian Integration count: 2500 times <Branch degree calculation method>
Calculation method of 5 carbon atoms (N _C5 , unit: 1 / 1000C)
In a ¹³ C-NMR spectrum in which an exponential is applied to the window function, a peak area of a peak having a peak top in the vicinity of 32.5 to 32.7 ppm, assuming that the sum of all peaks observed at 5 to 50 ppm is 1000 Asked.
Number of branches having 6 or more carbon atoms (N _LCB , unit: 1 / 1000C)
In a ¹³ C-NMR spectrum in which exponential is applied to the window function, the peak area of a peak having a peak top in the vicinity of 38.09 to 38.27 ppm, where the sum of all peaks observed at 5 to 50 ppm is 1000 Is A. This A is a value corresponding to a branched methine carbon having 4 or more carbon atoms. In the ¹³ C-NMR spectrum in which Gaussian was applied to the window function in order to separate the peaks of branched methine carbon having 5 or less carbon atoms and branched methine carbon having 6 or more carbon atoms, The peak observed at 38.27 ppm is B, and the peak observed at 38.21 to 38.09 ppm is C. And _NLCB was _{calculated |} required from the following formula _| equation.
N _LCB = A × B / (B + C)

[Physical properties of film]

(8) Tear strength (unit: kN / m 2)
The measurement was performed according to the method defined in ASTM D1922.

(9) Dirt impact strength (unit: kJ / m)
The measurement was performed according to the method (Method A) defined in ASTM D1709. Higher values indicate better impact resistance.

(10) A heat-shrinkable 9 cm long and 9 cm wide film test piece is sandwiched between two stainless steel meshes of 10.5 cm long and 10.5 cm wide and 100 mesh, and the film test piece is fixed, and then kept at a predetermined temperature. It was immersed in the adjusted oil bath for 5 seconds and subjected to heat treatment. About each of MD direction and TD direction, the dimension of the film test piece before and behind a process was measured, and the thermal contraction rate was computed by the following formula.
Thermal shrinkage (%) = [{(Dimension before heat treatment) − (Dimension after heat treatment)} / (Dimension before heat treatment)] × 100

(11) Blocking (unit: N / m2)
Using a 225 mm × 100 mm film, the films were overlapped, and the condition of the range of 100 mm × 100 mm was adjusted at 40 ° C. for 1 week under a load of 40 kg / cm 2. Thereafter, the sample was left in an atmosphere of 23 ° C. and 50% humidity for 30 minutes or more, and the strength required for peeling the sample was measured at a peeling rate of 20 g / min using a Shimadzu blocking tester. Smaller numbers indicate less blocking.

(12) Adhesive strength (unit: N / 25mm width)
The initial adhesive strength was measured by the following procedures (i) to (iv), and the adhesive strength after aging at a predetermined temperature (40 ° C. or 60 ° C.) was measured by the procedures (v) to (viii). If adhesive strength is 0.03 or more, it can be said that it has adhesiveness.
(I) Affix the adhesive film on the acrylic plate.
(Ii) This is pressure-bonded with a rubber-coated roller weighing 5 kg.
(Iii) Leave at 23 ° C. for 30 minutes.
(Iv) In an atmosphere of 23 ° C., the force (peeling force) required to peel the adhesive film from the acrylic plate was measured under conditions of a peeling width of 25 mm, a peel angle of 180 °, and a peeling speed of 300 mm / min. The adhesive strength (N / 25 mm width) was used.
(V) Affix the adhesive film to the acrylic plate.
(Vi) This is pressure-bonded with a rubber-coated roller weighing 5 kg.
(Vii) After leaving at a predetermined temperature for 1 hour, leave at 23 ° C. for about 30 minutes.
(Viii) In an atmosphere of 23 ° C., the force (peeling force) required to peel the adhesive film from the acrylic plate under the conditions of a peeling width of 25 mm, a peel angle of 180 °, and a peeling speed of 300 mm / min is measured, and after aging Adhesive strength (N / 25 mm width).

[Example 1]
(1) Preparation of co-catalyst support Silica (Sypolol 948 manufactured by Devison Corp .; 50% volume average particle size = 55 μm; pore capacity = 1.67 ml / g; specific surface area = 325 m ² / g) 2.8 kg and 24 kg of toluene were added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 0.9 kg of 1,1,1,3,3,3-hexamethyldisilazane and 1.4 kg of toluene was maintained for 30 minutes while maintaining the reactor temperature at 5 ° C. It was dripped at. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour, then heated to 95 ° C., stirred at 95 ° C. for 3 hours, and filtered. The obtained solid product was washed 6 times with 20.8 kg of toluene. Thereafter, 7.1 kg of toluene was added to form a slurry, which was allowed to stand overnight.

To the slurry obtained above, 3.46 kg of diethylzinc in hexane (diethylzinc concentration: 50% by weight) and 2.05 kg of hexane were added and stirred. Then, after cooling to 5 ° C., a mixed solution of 1.54 kg of 3,4,5-trifluorophenol and 2.88 kg of toluene was added dropwise over 60 minutes while maintaining the temperature of the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour, then heated to 40 ° C. and stirred at 40 ° C. for 1 hour. Then cooled to 5 ° C., was added dropwise for 1.5 hours while maintaining the H ₂ O0.221kg the temperature of the reactor to 5 ° C.. After completion of dropping, the mixture was stirred at 5 ° C for 1.5 hours, then heated to 40 ° C, stirred at 40 ° C for 2 hours, further heated to 80 ° C, and stirred at 80 ° C for 2 hours. After stirring, at room temperature, the supernatant was withdrawn to a residual amount of 16 L, charged with 11.6 kg of toluene, then heated to 95 ° C. and stirred for 4 hours. After stirring, the supernatant liquid was extracted at room temperature to obtain a solid product. The obtained solid product was washed 4 times with 20.8 kg of toluene and 3 times with 24 liters of hexane. Thereafter, drying was performed to obtain a solid component (hereinafter referred to as a promoter support (a)).

(2) Preparation of pre-polymerization catalyst component After adding 80 liters of butane to an autoclave equipped with a stirrer with an internal volume of 210 liters previously purged with nitrogen, 144 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide was added and the autoclave The mixture was heated to 50 ° C. and stirred for 2 hours. Next, 0.5 kg of the cocatalyst carrier (a) is charged and the autoclave is cooled to 31 ° C. to stabilize the system, and then 0.1 kg of ethylene and 0.1 liter of hydrogen (room temperature and normal pressure volume) are charged. Subsequently, 207 mmol of triisobutylaluminum was added to initiate polymerization. After 30 minutes while continuously supplying ethylene and hydrogen at 0.6 kg / Hr and 0.5 liter (room temperature and normal pressure volume), respectively, the temperature was raised to 50 ° C., and ethylene and hydrogen were each 3.6 kg / Hr. And 10.9 liters (room temperature and normal pressure volume) / hour were continuously fed for a total of 6 hours of prepolymerization. After the polymerization was completed, ethylene, butane, hydrogen and the like were purged and the remaining solid was vacuum dried at room temperature to obtain a prepolymerized catalyst component containing 37 g of polyethylene per 1 g of the promoter support (a). The [η] of the polyethylene was 1.51 dl / g.

(3) Production of ethylene-1-butene-1-hexene copolymer Using the above prepolymerization catalyst component, copolymerization of ethylene, 1-butene and 1-hexene was performed in a continuous fluidized bed gas phase polymerization apparatus. did. The polymerization conditions were a temperature of 84 ° C., a total pressure of 2 MPa, a molar ratio of hydrogen to ethylene of 1.04%, a molar ratio of 1-butene to ethylene of 2.16%, and a molar ratio of 1-hexene to ethylene of 0.73. %, Ethylene, 1-butene, 1-hexene and hydrogen were continuously fed to keep the gas composition constant during the polymerization. Further, the pre-polymerization catalyst component and triisobutylaluminum were continuously supplied at a constant ratio so that the total powder weight of the fluidized bed was maintained at 80 kg and the average polymerization time was 4 hours. By polymerization, a powder of ethylene-1-butene-1-hexene copolymer (hereinafter referred to as PE-1) was obtained at a polymerization efficiency of 22.9 kg / hour.

(4) Granulation of ethylene-1-butene-1-hexene copolymer powder The PE-1 powder obtained above was fed with an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, screw rotation. PE-1 pellets were obtained by granulation under conditions of several 450 rpm, a gate opening of 4.2 mm, a suction pressure of 0.2 MPa, and a resin temperature of 200 to 230 ° C. The evaluation results of PE-1 pellets are shown in Table 1.

(5) Preparation of prepolymerization catalyst component (2) 80 liters of butane was added to an autoclave with an internal volume of 210 liters previously purged with nitrogen, and then 144 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide was added. The autoclave was heated to 50 ° C. and stirred for 2 hours. Next, 0.5 kg of the cocatalyst carrier (a) is charged and the autoclave is cooled to 31 ° C. to stabilize the system, and then 0.1 kg of ethylene and 0.1 liter of hydrogen (room temperature and normal pressure volume) are charged. Subsequently, 207 mmol of triisobutylaluminum was added to initiate polymerization. After 30 minutes passed while continuously supplying ethylene and hydrogen at 0.6 kg / Hr and 0.5 liter (normal temperature and normal pressure volume), respectively, the temperature was raised to 50 ° C., and ethylene and hydrogen were each 3.6 kg / hour. And 10.9 liters (room temperature and normal pressure volume) / hour were continuously fed for a total of 6 hours of prepolymerization. After the polymerization was completed, ethylene, butane, hydrogen and the like were purged and the remaining solid was vacuum dried at room temperature to obtain a prepolymerized catalyst component (2) containing 37 g of polyethylene per 1 g of the promoter support (a).

(6) Production of ethylene-1-hexene copolymer Using the above prepolymerization catalyst component (2), copolymerization of ethylene and 1-hexene was carried out in a continuous fluidized bed gas phase polymerization apparatus. The polymerization conditions were a temperature of 80 ° C., a total pressure of 2 MPa, a molar ratio of hydrogen to ethylene of 1.48%, and a molar ratio of 1-hexene to ethylene of 1.70% to maintain a constant gas composition during the polymerization. Ethylene, 1-hexene and hydrogen were continuously fed to the reactor. Furthermore, the pre-polymerization catalyst component and triisobutylaluminum were continuously supplied at a constant ratio so that the total powder weight of the fluidized bed was maintained at 80 kg and the average polymerization time was 4 hours. By polymerization, a powder of an ethylene-1-hexene copolymer (hereinafter referred to as PE-2) was obtained at a polymerization efficiency of 20.3 kg / hour.

(7) Granulation of ethylene-1-hexene copolymer powder The PE-2 powder obtained above was fed using an extruder (LCM50, manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, and a gate. PE-2 pellets were obtained by granulation under conditions of an opening degree of 4.2 mm, a suction pressure of 0.2 MPa, and a resin temperature of 200 to 230 ° C. The evaluation results of PE-2 pellets are shown in Table 1.

(8) Film molding 96 parts by weight of the above PE-1 pellets and 4 parts by weight of a commercially available antioxidant masterbatch (manufactured by Sumitomo Chemical Co., Ltd., “CMB-735”; hereinafter referred to as AO-MB). The outer layer of a three-layer coextrusion inflation molding machine (die system 100 mm, lip opening 2.0 mm) consisting of three extruders with a screw diameter of 50 mmφ is mixed with the pellets uniformly using a tumbler mixer. It was introduced into an extruder for an intermediate layer and an extruder for an intermediate layer, and 96 parts by weight of the above PE-2 pellets and 4 parts by weight of AO-MB were uniformly mixed using a tumbler mixer. The mixture was introduced into an extruder for the inner layer, the molding temperature was set to an extruder, the die set temperature was set to 190 ° C., and the extrusion rates of the intermediate layer, the inner layer, and the outer layer were each 12 kg / hour. Reishio were co-extrusion inflation molding thickness 50μm at 3.5 conditions. Table 2 shows the physical property evaluation results of the obtained multilayer film. The outer layer and the inner layer are base material layers, and the inner layer is an adhesive layer.

[Example 2]

(1) Preparation of prepolymerization catalyst component (3) 70 liters of butane was introduced into an autoclave with a stirrer having an internal volume of 210 liters that had been previously purged with nitrogen, and then 30.7 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide. The autoclave was heated to 50 ° C. and stirred for 5 hours. Next, after the temperature of the autoclave was lowered to 30 ° C. and the system was stabilized, 0.03 MPa of ethylene was charged at the gas phase pressure in the autoclave, and 0.7 kg of the promoter support (a) was added, followed by triisobutyl. Polymerization was started by adding 123 mmol of aluminum. After 30 minutes while continuously supplying ethylene at 0.7 kg / hour, the temperature was raised to 50 ° C., and ethylene and hydrogen were supplied at 2.8 kg / hour and 8.5 liters (room temperature and normal pressure volume) / Hr, respectively. A total of 5.5 hours of prepolymerization was carried out by continuous feeding. After completion of the polymerization, ethylene, butane, hydrogen gas, etc. are purged and the remaining solid is vacuum-dried at room temperature, and a prepolymerized catalyst component (20.5 g of polyethylene is preliminarily polymerized per 1 g of the promoter support (a) ( 3) was obtained.

(2) Production of ethylene-1-hexene copolymer Using the prepolymerized catalyst component (3) obtained above, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus, I got a powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.63%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 0.78%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. In addition, the prepolymerization catalyst component and triisobutylaluminum were continuously supplied, and the total powder weight of 80 kg in the fluidized bed was kept constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene-1 copolymer (hereinafter referred to as PE-3) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

(3) Granulation of ethylene-1-hexene copolymer powder The PE-3 powder obtained above was fed with an extruder (LCM50, manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw rotation speed of 450 rpm, and a gate. PE-3 pellets were obtained by granulation under conditions of an opening degree of 4.2 mm, a suction pressure of 0.2 MPa, and a resin temperature of 200 to 230 ° C. The evaluation results of PE-3 pellets are shown in Table 1.

(4) Film molding In the inflation molding, 96 parts by weight of the above PE-3 pellets and 4 parts by weight of AO-MB are mixed uniformly into the resin to be introduced into the intermediate layer extruder using a tumbler mixer. The same procedure as in Example 1 was performed except that the above was performed. The evaluation results of the obtained film are shown in Table 2. The outer layer and the intermediate layer are substrate layers, and the inner layer is an adhesive layer.

[Comparative Example 1]
In the inflation molding, a resin introduced into the inner layer extruder is a commercially available ethylene-1-hexene copolymer (manufactured by Sumitomo Chemical Co., Ltd., “Sumikasen Hiα FW201-0” (density = 912 kg / m ³ , melt flow rate = 2). 0.0 g / 10 min); hereinafter referred to as LL-1, the physical properties of LL-1 are shown in Table 1. The same procedure as in Example 1 was carried out except that the pellets of 100 parts by weight were used. The evaluation results of the obtained film are shown in Table 2.

[Comparative Example 2]
In the inflation molding, a resin introduced into the inner layer extruder is a commercially available ethylene-1-hexene copolymer (manufactured by Sumitomo Chemical Co., Ltd., “Sumikasen Hiα CW5001” (density = 908 kg / m ³ , melt flow rate = 13 g / 10 Min); hereinafter referred to as LL-2, the physical properties of LL-2 are shown in Table 1. The same procedure as in Example 1 was carried out except that the pellet of 100 parts by weight was used. The evaluation results of the obtained film are shown in Table 2.

[Comparative Example 3]
(1) Film molding 100 parts by weight of PE-1 pellets were introduced into a single screw extruder with a screw diameter of 55 mmφ and an inflation molding machine with a lip diameter of 75 mmφ and a lip gap of 2.0 mm (manufactured by SHI Modern Machinery Co., Ltd.). Inflation molding was performed under the conditions of a temperature (extruder and die setting temperature) of 160 ° C., an extrusion rate of 25 kg / hr, and a blow-up ratio of about 3.5 to obtain a single-layer film having a thickness of 50 μm. Table 3 shows the physical property evaluation results of the obtained single-layer film.

[Comparative Example 4]
(1) Preparation of prepolymerization catalyst component (4) Into an autoclave with a stirrer having an internal volume of 210 liters, which had been previously purged with nitrogen, 80 liters of butane was added, and then 144 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide was added. The autoclave was heated to 50 ° C. and stirred for 2 hours. Next, 0.5 kg of the cocatalyst carrier (a) is charged and the autoclave is cooled to 31 ° C. to stabilize the system, and then 0.1 kg of ethylene and 0.1 liter of hydrogen (room temperature and normal pressure volume) are charged. Subsequently, 207 mmol of triisobutylaluminum was added to initiate polymerization. After 30 minutes while continuously supplying ethylene and hydrogen at 0.6 kg / hour and 0.5 liter (room temperature and normal pressure volume), respectively, the temperature was raised to 50 ° C., and ethylene and hydrogen were each 3.6 kg / hour. And 10.9 liters (room temperature and normal pressure volume) / hour were continuously fed for a total of 6 hours of prepolymerization. After the polymerization was completed, ethylene, butane, hydrogen and the like were purged, and the remaining solid was vacuum dried at room temperature to obtain a prepolymerized catalyst component (4) containing 37 g of polyethylene per 1 g of the promoter support (a). The [η] of the polyethylene was 1.51 dl / g.

(2) Production of ethylene-1-butene-1-hexene copolymer Copolymerization of ethylene, 1-butene and 1-hexene in a continuous fluidized bed gas phase polymerization apparatus using the prepolymerization catalyst component (4) described above. Polymerization was performed. The polymerization conditions were a temperature of 84 ° C., a total pressure of 2 MPa, a molar ratio of hydrogen to ethylene of 1.4%, a molar ratio of 1-butene to ethylene of 2.3%, and a molar ratio of 1-hexene to ethylene of 1.0%. %, Ethylene, 1-butene, 1-hexene and hydrogen were continuously fed to keep the gas composition constant during the polymerization. Further, the pre-polymerization catalyst component and triisobutylaluminum were continuously supplied at a constant ratio so that the total powder weight of the fluidized bed was maintained at 80 kg and the average polymerization time was 4 hours. By polymerization, a powder of ethylene-1-butene-1-hexene copolymer (hereinafter referred to as PE-4) was obtained at a polymerization efficiency of 22.9 kg / hour.

(3) Granulation of ethylene-1-butene-1-hexene copolymer powder The PE-4 powder obtained above was fed with an extruder (LCM50 manufactured by Kobe Steel Ltd.) at a feed rate of 50 kg / hour and screw rotation. PE-4 pellets were obtained by granulation under conditions of several 450 rpm, a gate opening of 4.2 mm, a suction pressure of 0.2 MPa, and a resin temperature of 200 to 230 ° C. Table 1 shows the evaluation results of the PE-4 pellets.

(4) Film forming Inflation forming was performed in the same manner as in Comparative Example 3 except that the PE-4 pellet was changed to 100 parts by weight. The evaluation results of the obtained film are shown in Table 3.

Claims (3)

Layer 1 containing polyethylene resin (A) that satisfies all of the following requirements (a1), (a2), and (a3), and polyethylene that satisfies all of the following requirements (b1), (b2), and (b3) Heat-shrinkable film (a1) having layer 2 containing a resin (B): The number of branches having 6 or more carbon atoms (N _LCB ) measured by ¹³ C-NMR is 0.01 or more per 1000 carbon atoms And the number of branches having 5 carbon atoms (N _C5 ) is less than 0.1 per 1000 carbon atoms (a2): the flow activation energy (Ea) is 40 kJ / mol or more (a3) ): Density is 920 kg / m ³ or more (b1): The number of branches having 6 or more carbon atoms (N _LCB ) measured by ¹³ C-NMR is 0.01 or more per 1000 carbon atoms, and Number of branches with 5 carbon atoms N _C5) is less than 0.1 per 1000 carbon atoms (b2): that activation energy of flow (Ea) is 40 kJ / mol or more (b3): density is 900~915kg / ^{m 3} thing The polyethylene-based resin (A) has a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies the following requirement (a4): ethylene-α- The heat-shrinkable film according to claim 1, which is an olefin copolymer.
(A4): Molecular weight distribution (Mw / Mn) is 5 to 25 The polyethylene-based resin (B) has a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies the following requirement (b4): ethylene-α- The heat-shrinkable film according to claim 1 or 2, which is an olefin copolymer.
(B4): The molecular weight distribution (Mw / Mn) is 5-25.