JP2013001796A - Film for stretch label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for stretch labels, which is excellent in self-flexibility, stiffness and processability when the film is formed.SOLUTION: The film for stretch labels contains 50-90 wt.% of an ethylene-α-olefin copolymer (A) satisfying the following conditions (a1), (a2) and (a3) and 10-50 wt.% of an ethylene-α-olefin copolymer (B) satisfying the following conditions (b1), (b2) and (b3). The condition (a1) is that the activation energy of fluidization is ≥40 kJ/mol; the condition (a2) is that the molecular weight distribution is 5-25; and the condition (a3) is that the melt flow rate is 0.9-3 g/10 minutes. The condition (b1) is that the activation energy of fluidization is ≤35 kJ/mol; the condition (b2) is that the melt flow rate is 2-10 g/10 minutes; and the condition (b3) is that the density is 900-915 kg/m.

Description

  The present invention relates to a film for stretch labels.

  Films made of an ethylene-α-olefin copolymer are widely used as packaging films. For example, Patent Document 1 describes a film made of a resin composition containing two types of ethylene-α-olefin copolymers having different physical properties.

JP 2007-262280 A

As a kind of packaging film, there is a stretch label film used for a label attached to a plastic bottle, and a stretch label film made of an ethylene-α-olefin copolymer is also known. In order for the stretch label to adhere to the bottle without sagging, the stretch label film is required to shrink well after being stretched at room temperature (self-stretchability) and to be excellent in rigidity. The film made of the resin composition is not sufficiently rigid to be used for a stretch label, and improvement in workability during film formation has been demanded.
Under such circumstances, the problem to be solved by the present invention is to provide a film for stretch label that is excellent in self-stretchability, rigidity, and workability during film formation.

The present invention includes a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies all of the following requirements (a1), (a2) and (a3). Ethylene-α-olefin copolymer (A) 50 wt% or more and 90 wt% or less,
Ethylene-α- which includes a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies all of the following requirements (b1), (b2) and (b3) Olefin copolymer (B) 10 wt% or more and 50 wt% or less (however, the total amount of ethylene-α-olefin copolymer (A) and ethylene-α-olefin copolymer (B) is 100 wt%) %) For stretch labels.
Ethylene-α-olefin copolymer (A)
(A1) Flow activation energy is 40 kJ / mol or more.
(A2) The molecular weight distribution is 5 or more and 25 or less.
(A3) The melt flow rate is 0.9 g / 10 min or more and 3 g / 10 min or less.
Ethylene-α-olefin copolymer (B)
(B1) Flow activation energy is 35 kJ / mol or less.
(B2) The melt flow rate is 2 g / 10 min or more and 10 g / 10 min or less.
(B3) density 900 kg / ^{m 3} or more 915 kg / ^{m 3} that less.

  ADVANTAGE OF THE INVENTION According to this invention, the film for stretch labels which is excellent in self-stretchability, rigidity, and the workability at the time of film forming can be provided.

  The ethylene-α-olefin copolymer (A) used in the present invention comprises an ethylene-α-olefin containing a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms. It is a copolymer. 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 and 4-methyl. -1-pentene, 4-methyl-1-hexene and the like can be mentioned, and these may be used alone or in combination of two or more. The α-olefin is preferably 1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene, and more preferably 1-butene or 1-hexene.

  Content of the monomer unit based on ethylene of the ethylene-α-olefin copolymer (A) used in the present invention is based on the total weight (100% by weight) of the ethylene-α-olefin copolymer (A). Usually, it is 50 to 99.5% by weight. Moreover, content of the monomer unit based on an alpha olefin is 0.5-50 weight% normally with respect to the total weight (100 weight%) of an ethylene-alpha-olefin copolymer (A).

  Examples of the ethylene-α-olefin copolymer (A) used in the present invention include an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, and an ethylene-4-methyl-1-pentene copolymer. A copolymer, an ethylene-1-octene copolymer, an ethylene-1-butene-1-hexene copolymer, an ethylene-1-hexene-1-octene copolymer, and the like, preferably an ethylene-1-butene copolymer. A polymer is an ethylene-1-hexene copolymer.

  The flow activation energy of the ethylene-α-olefin copolymer (A) used in the present invention (hereinafter sometimes referred to as “Ea”) is 40 kJ / mol or more. The flow activation energy of the ethylene-α-olefin copolymer (A) is preferably 50 kJ / mol or more, more preferably 60 kJ / mol or more, further preferably, from the viewpoint of excellent self-stretchability. 65 kJ / mol or more. Moreover, it is preferably 90 kJ / mol or less, more preferably 85 kJ / mol or less, still more preferably 80 kJ / mol or less, and particularly preferably 75 kJ / mol or less.

The activation energy (Ea) of the flow is dependent on the angular frequency (unit: rad / sec) dependence of the melt complex viscosity (unit: Pa · sec) at 190 ° C. based on the temperature-time superposition principle. It is a numerical value calculated by the Arrhenius type equation from the shift factor (a _T ) when creating the master curve shown, and is a value obtained by the method shown below. 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 melt complex viscosity is Pa · sec. 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. 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 device (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 molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer (A) of the present invention is 5 or more and 25 or less. From the viewpoint of reducing the extrusion load, the Mw / Mn of the ethylene-α-olefin copolymer (A) is more preferably 7 or more, and further preferably 8 or more. Further, from the viewpoint that film formation can be performed at high speed, Mw / Mn of the ethylene-α-olefin copolymer (A) is more preferably 18 or less, and further preferably 15 or less. The value of the molecular weight distribution (Mw / Mn) is determined from the molecular weight distribution curve obtained by gel permeation chromatography method and the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene. , Mw is divided by Mn.

The melt flow rate of the ethylene-α-olefin copolymer (A) used in the present invention (hereinafter sometimes referred to as “MFR”) is 0.9 g / 10 min or more and 3 g / 10 min or less. . The melt flow rate is preferably 1.2 g / 10 min or more from the viewpoint that a film can be easily formed by T-die molding. The melt flow rate, which is preferably 2.5 g / 10 min or less, more preferably 2.3 g / 10 min or less, is a method defined in JIS K7210-1995, with a temperature of 190 ° C. and a load of 21. It is a value measured by the method A under the condition of 18N.
The melt flow rate of the ethylene-α-olefin copolymer can be changed by, for example, the hydrogen concentration or the polymerization temperature in the production method described later. When the hydrogen concentration or the polymerization temperature is increased, the ethylene-α-olefin copolymer The melt flow rate of coalescence increases.

The density of the ethylene-α-olefin copolymer (A) used in the present invention (hereinafter sometimes referred to as “d”) is preferably 910 kg / m ³ or more from the viewpoint of high film rigidity. It is. Also, preferably at 926kg / ^{m 3} or less, more preferably 920 kg / ^{m 3} or less. The density is measured according to the method defined in Method A of JIS K7112-1980 after annealing described in JIS K6760-1995.
The density of the ethylene-α-olefin copolymer (A) can be changed depending on the content of monomer units based on ethylene in the ethylene-α-olefin copolymer.

  The melt flow rate ratio of the ethylene-α-olefin copolymer (A) used in the present invention (hereinafter sometimes referred to as “MFRR”) is preferably 30 or more from the viewpoint of reducing the extrusion load. More preferably, it is 50 or more, More preferably, it is 70 or more. Moreover, from a viewpoint that a film forming process can be performed at high speed, it is preferably 200 or less, and more preferably 150 or less. The MFRR is a melt flow rate (hereinafter sometimes referred to as “H-MFR”) measured under conditions of a load of 211.82 N and a temperature of 190 ° C. in the method defined in JIS K7210-1995. In the method defined in JIS K7210-1995, it is a value divided by the melt flow rate (MFR) measured under conditions of a load of 21.18 N and a temperature of 190 ° C. In addition, MFRR can be changed by, for example, the hydrogen concentration in the production method described later. When the hydrogen concentration is increased, the MFRR of the ethylene-α-olefin copolymer is decreased.

  As the method for producing the ethylene-α-olefin copolymer (A) of the present invention, for example, a solid particulate material obtained by supporting an organic zinc compound as a promoter on a particulate compound is used as a promoter component (hereinafter referred to as component). A transition metal compound having a ligand having a structure in which two cyclopentadienyl type anion skeletons are bonded to each other by a bridging group such as an alkylene group or a silylene group (hereinafter referred to as component (b)). And a method of copolymerizing ethylene and an α-olefin in the presence of a polymerization catalyst.

  Examples of the component (a) include a component in which methylalumoxane is mixed with porous silica, a component in which diethyl zinc, water, and fluorinated phenol are mixed with porous silica.

More specific examples of component (a) include component (a) diethylzinc, component (b) fluorinated phenol, component (c) water, component (d) porous silica and component (e) 1,1,1, Preferred is a promoter component (hereinafter referred to as component (I) -2) obtained by contacting 3,3,3-hexamethyldisilazane (((CH ₃ ) ₃ Si) ₂ NH). .

  Preferred examples of the fluorinated phenol as component (b) include pentafluorophenol, 3,5-difluorophenol, 3,4,5-trifluorophenol, 2,4,6-trifluorophenol, and the like. From the viewpoint of increasing the flow activation energy (Ea) and molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer, it is preferable to use two types of fluorinated phenols having different fluorine numbers. The molar ratio of phenol having a large number of fluorines to phenol having a small number of fluorines is usually 20/80 to 80/20, and a higher molar ratio of phenol having a small number of fluorines is preferred.

The amount of component (a), component (b) and component (c) used is the molar ratio of the amount of each component used: component (a): component (b): component (c) = 1: y: z Then, it is preferable that y and z satisfy the following formula.
| 2-y-2z | ≦ 1
Y in the above formula is preferably a number of 0.01 to 1.99, more preferably a number of 0.10 to 1.80, and still more preferably a number of 0.20 to 1.50. Most preferably, the number is 0.30 to 1.00.

  The amount of the component (d) used relative to the component (a) is such that the number of moles of zinc atoms contained in the particles obtained by contacting the component (a) and the component (d) is 0.00 per gram of the particles. The amount is preferably 1 mmol or more, and more preferably 0.5 to 20 mmol. The amount of the component (e) to be used with respect to the component (d) is preferably an amount that makes the component (e) 0.1 mmol or more per 1 g of the component (d), and an amount that becomes 0.5 to 20 mmol. More preferably.

  The component (b) includes a zirconocene complex in which two indenyl groups are bonded by a crosslinking group such as an ethylene group, a dimethylmethylene group, and a dimethylsilylene group; Zirconocene complex in which a methylindenyl group is bonded (bridged bisindenylzirconium complex); Zirconocene complex in which two methylcyclopentadienyl groups are bonded by a crosslinking group such as ethylene, dimethylmethylene, and dimethylsilylene; And a zirconocene complex in which two dimethylcyclopentadienyl groups are bonded by a bridging group such as a dimethylmethylene group and a dimethylsilylene group. Moreover, as a metal atom of a component (b), a zirconium and hafnium are preferable, and also as a remaining substituent which a metal atom has, a diphenoxy group and a dialkoxy group are preferable. From the viewpoint of increasing the flow activation energy (Ea) of the ethylene-α-olefin copolymer, it is preferable to use a crosslinked bisindenylzirconium complex as the component (b), and ethylenebis (1-indenyl) zirconium. More preferably, diphenoxide is used.

  In the polymerization catalyst comprising the above component (a) and component (b), an organoaluminum compound may be used as a co-catalyst component as appropriate. Examples of the organoaluminum compound include triisobutylaluminum, trinormal Examples include octyl aluminum.

The amount of the component (b) used is preferably 5 × 10 ^{−6 to} 5 × 10 ⁻⁴ mol per 1 g of the component (b). The amount of the organoaluminum compound used is preferably such that the aluminum atom of the organoaluminum compound is 1 to 2000 mol per mol of the metal atom of the metallocene complex.

  In addition, in the polymerization catalyst comprising the above component (a) and component (b), an electron donating compound may be used as a catalyst component as appropriate. Examples of the electron donating compound include triethylamine, Examples thereof include normal octylamine.

  When two types of fluorinated phenols having different numbers of fluorine are used as the component (b) fluorinated phenol, it is preferable to use an electron donating compound in combination.

  The amount of the electron-donating compound used is usually 0.1 to 10 mol% with respect to the number of moles of aluminum atoms in the organoaluminum compound used as the promoter component, and the MFRR and molecular weight distribution (Mw / Mn). From the viewpoint of increasing the size, it is preferable that the amount used is large.

  More specifically, the method for producing the ethylene-α-olefin copolymer (A) of the present invention comprises contacting the component (I) -2, a crosslinked bisindenylzirconium complex and an organoaluminum compound. Examples thereof include a method of copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a catalyst.

  The polymerization method of the ethylene-α-olefin copolymer (A) of the present invention is preferably a continuous polymerization method involving the formation of particles of the ethylene-α-olefin copolymer, for example, continuous gas phase polymerization, continuous Slurry polymerization and continuous bulk polymerization are preferred, and continuous gas phase polymerization is preferred. The gas phase polymerization reaction apparatus is usually an apparatus having a fluidized bed type reaction tank, and preferably an apparatus having a fluidized bed type reaction tank having an enlarged portion. A stirring blade may be installed in the reaction vessel.

  The polymerization temperature in the gas phase polymerization or slurry polymerization of the ethylene-α-olefin copolymer (A) of the present invention is usually lower than the temperature at which the ethylene-α-olefin copolymer melts, preferably 0-150. ° C, more preferably 30 to 100 ° C, still more preferably 50 to 90 ° C. From the viewpoint of increasing the molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer and increasing the MFRR, a higher polymerization temperature is preferred. An inert gas may be introduced into the polymerization reaction tank, and hydrogen may be introduced as a molecular weight regulator. Further, an organoaluminum compound or an electron donating compound may be introduced.

  The polymerization temperature in bulk polymerization is usually 150 to 300 ° C.

  The polymerization temperature in the solution polymerization is usually 150 to 300 ° C.

  The polymerization time is usually 1 to 20 hours (as an average residence time in the case of a continuous polymerization reaction). From the viewpoint of increasing the molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer, a longer polymerization time (average residence time) is preferable.

  Further, for the purpose of adjusting the melt fluidity of the copolymer, hydrogen may be added to the polymerization reaction gas as a molecular weight regulator, and an inert gas may be allowed to coexist in the polymerization reaction gas. The molar concentration of hydrogen in the polymerization reaction gas with respect to the molar concentration of ethylene in the polymerization reaction gas is usually 0.1 to 3 mol% as the molar concentration of ethylene in the polymerization reaction gas is 100 mol%. By increasing the molar concentration of hydrogen in the polymerization reaction gas, the molecular weight distribution (Mw / Mn) of the obtained ethylene-α-olefin copolymer can be increased, and the MFRR can be increased. However, if the hydrogen concentration is excessively high, the impact resistance decreases.

  When the α-olefin concentration is lowered in the polymerization reaction gas, a high-density ethylene-α-olefin copolymer can be obtained, and the rigidity can be improved.

  As a method for supplying each component of the polymerization catalyst used in the production of the ethylene-α-olefin copolymer (A) of the present invention to the reaction vessel, usually inert gas such as nitrogen and argon, hydrogen, ethylene, etc. And a method in which the components are supplied without moisture, and a method in which each component is dissolved or diluted in a solvent and supplied in a solution or slurry state. Each component of the polymerization catalyst may be supplied individually, or arbitrary components may be supplied in contact in advance in any order.

  As a method for producing the ethylene-α-olefin copolymer (A) of the present invention, a small amount of a transition metal compound, a promoter component, and, if necessary, an organoaluminum compound and an electron donating compound are used. A method in which ethylene and an α-olefin are copolymerized using a prepolymerized solid component obtained by polymerizing the olefin (hereinafter referred to as prepolymerization) as a polymerization catalyst component or a polymerization catalyst is preferred.

  Examples of the olefin used in the prepolymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, cyclopentene and cyclohexene. These may be used alone or in combination of two or more. Preferably, ethylene is used alone, or ethylene and α-olefin are used in combination. More preferably, ethylene is used alone, or at least one α-olefin selected from 1-butene, 1-hexene and 1-octene is used in combination with ethylene.

  The content of the prepolymerized polymer in the prepolymerized solid component is preferably 0.01 to 1000 g, more preferably 0.05 to 500 g, still more preferably 0.1 per g of the promoter component. ~ 200 g.

  The preliminary polymerization method may be a continuous polymerization method or a batch polymerization method, and examples thereof include a batch type slurry polymerization method, a continuous slurry polymerization method, and a continuous gas phase polymerization method. As a method of introducing a transition metal compound, a promoter component, and, if necessary, an organoaluminum compound and an electron donating compound into a polymerization reaction tank for performing prepolymerization, an inert gas such as nitrogen or argon is usually used. A method of using hydrogen, ethylene, or the like in a state without moisture, or a method of dissolving or diluting each component in a solvent and adding in a solution or slurry state is used.

  When the prepolymerization is performed by a slurry polymerization method, a saturated aliphatic hydrocarbon compound is usually used as the solvent, and examples thereof include propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, cyclohexane, heptane and the like. . These may be used alone or in combination of two or more. The saturated aliphatic hydrocarbon compound preferably has a boiling point of 100 ° C. or less at normal pressure, more preferably 90 ° C. or less at normal pressure, and propane, normal butane, isobutane, normal pentane, isopentane, normal hexane. More preferred is cyclohexane.

  Moreover, when performing prepolymerization by a slurry polymerization method, as a slurry density | concentration, the quantity of the promoter component per liter of solvent is 0.1-600g normally, Preferably it is 0.5-300g. The prepolymerization temperature is usually -20 to 100 ° C, preferably 0 to 80 ° C. During the prepolymerization, the polymerization temperature may be appropriately changed. Moreover, the partial pressure of olefins in the gas phase part during the prepolymerization is usually 0.001 to 2 MPa, preferably 0.01 to 1 MPa. The prepolymerization time is usually 2 minutes to 15 hours.

  As a method of supplying the prepolymerized prepolymerized solid catalyst component to the polymerization reaction vessel, a method of supplying using an inert gas such as nitrogen and argon, hydrogen, ethylene, etc., each component is dissolved or diluted in a solvent. Thus, a method of supplying in a solution or slurry state is used.

  The ethylene-α-olefin copolymer (B) used in the present invention is a copolymer comprising a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms. Preferably, it is a copolymer comprising a monomer unit based on ethylene and a monomer unit based on an α-olefin having 4 to 20 carbon atoms, more preferably a monomer unit based on ethylene and carbon. It is a copolymer containing a monomer unit based on an α-olefin having 4 to 8 atoms.

  Examples of the ethylene-α-olefin copolymer (B) used in the present invention include an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, and an ethylene-4-methyl-1-pentene copolymer. Polymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl-1-pentene copolymer, ethylene-1-butene-1-octene A copolymer, an ethylene-1-hexene-1-octene copolymer, and the like, preferably an ethylene-1-hexene copolymer, an ethylene-4-methyl-1-pentene copolymer, and an ethylene-1-butene. -1-hexene copolymer, ethylene-1-butene-1-octene copolymer, and ethylene-1-hexene-1-octene copolymer.

The flow activation energy of the ethylene-α-olefin copolymer (B) used in the present invention (hereinafter sometimes referred to as “Ea”) is 35 kJ / mol or less. The activation energy of the flow is preferably 25 kJ / mol or more.
The flow activation energy may be increased, for example, by increasing the polymerization temperature in the production method described later.

The melt flow rate (hereinafter sometimes referred to as “MFR”) of the ethylene-α-olefin copolymer (B) used in the present invention is 2 g / 10 min or more and 10 g / 10 min or less. The melt flow rate is preferably 8 g / 10 min or less, more preferably 6 g / 10 min or less, and even more preferably 4 g / 10 min or less from the viewpoint that a film can be easily formed by T-die molding. . The melt flow rate is a value measured by Method A under the conditions of a temperature of 190 ° C. and a load of 21.18 N in the method defined in JIS K7210-1995.
The melt flow rate of the ethylene-α-olefin copolymer (B) can be changed by, for example, the hydrogen concentration or the polymerization temperature in the production method described later. When the hydrogen concentration or the polymerization temperature is increased, the ethylene-α- The melt flow rate of the olefin copolymer (B) is increased.

The density of the ethylene -α- olefin copolymer used in the present invention (B) (hereafter, referred to sometimes as "d".) Is 900 kg / ^{m 3} or more 915 kg / ^{m 3} or less. From the viewpoint that the film of the present invention has excellent self-stretchability, the density is preferably 910 kg / m ³ or less. The density is measured according to the method defined in Method A of JIS K7112-1980 after annealing described in JIS K6760-1995.
The density of the ethylene-α-olefin copolymer (B) can be adjusted by increasing or decreasing the content of monomer units based on the α-olefin in the ethylene-α-olefin copolymer (B). The density can be lowered by increasing the content of monomer units based on α-olefins.

  The melt flow rate ratio of the ethylene-α-olefin copolymer (B) used in the present invention (hereinafter sometimes referred to as “MFRR”) is preferably 10 or more from the viewpoint of reducing the extrusion load. More preferably, it is 14 or more, More preferably, it is 18 or more. Moreover, from a viewpoint that a film forming process can be performed at high speed, it is preferably 45 or less, more preferably 40 or less, and further preferably 30 or less. The MFRR is a melt flow rate (hereinafter sometimes referred to as “H-MFR”) measured under conditions of a load of 211.82 N and a temperature of 190 ° C. in the method defined in JIS K7210-1995. In the method defined in JIS K7210-1995, it is a value divided by the melt flow rate (MFR) measured under conditions of a load of 21.18 N and a temperature of 190 ° C. In addition, MFRR can be changed by, for example, the hydrogen concentration in the production method described later. When the hydrogen concentration is increased, the MFRR of the ethylene-α-olefin copolymer is decreased.

  The molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer (B) used in the present invention is 3-9. From the viewpoint of reducing the extrusion load, the Mw / Mn of the ethylene-α-olefin copolymer (B) is preferably 4 or more, more preferably 5 or more. Moreover, from the viewpoint that film formation can be performed at high speed, Mw / Mn of the ethylene-α-olefin copolymer (B) is more preferably 8 or less, and further preferably 7 or less. The value of the molecular weight distribution (Mw / Mn) is determined from the molecular weight distribution curve obtained by gel permeation chromatography method and the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene. , Mw is divided by Mn.

  As the method for producing the ethylene-α-olefin copolymer (B), an olefin polymerization catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst is used, and a solution polymerization method, a slurry polymerization method, a gas phase polymerization method, Examples thereof include a production method by a polymerization method such as a legal method. The polymerization method may be either a batch polymerization method or a continuous polymerization method, and may be a multistage polymerization method having two or more stages.

  Examples of the Ziegler-Natta catalyst include a catalyst comprising a solid catalyst component for olefin polymerization containing a titanium atom, a magnesium atom and a halogen atom, and an organoaluminum compound. The catalyst described in 11-322833 gazette is mention | raise | lifted.

Examples of the metallocene catalyst include the following catalysts (1) to (4).
(1) A catalyst comprising a component containing a transition metal compound having a group having a cyclopentadiene skeleton and a component containing an alumoxane compound. (2) A component containing the transition metal compound and ions such as trityl borate and anilinium borate. catalyst comprising component containing a sex compound (3) wherein the component containing the transition metal compound, and a component containing an ionic compound, an organoaluminum compound and consists of components containing a catalyst (4) the components of the SiO ₂ Catalyst obtained by supporting or impregnating inorganic particulate carrier such as Al ₂ O ₃ or particulate polymer carrier such as olefin polymer such as ethylene and styrene

  Examples of the organometallic compound include butyllithium and triethylaluminum.

  As content of each component in the polyethylene-type resin composition used by this invention, ethylene-alpha-olefin copolymer (A) and ethylene-alpha-olefin copolymer (B) which are contained in this resin composition are used. When the total amount is 100% by weight, the content of the ethylene-α-olefin copolymer (A) is 50% by weight or more and 90% by weight or less, and the content of the ethylene-α-olefin copolymer (B) is 10%. % By weight or more and 50% by weight or less. From the viewpoint of excellent self-stretchability, the content of the ethylene-α-olefin copolymer (A) is preferably 58% by weight or more, and more preferably 60% by weight or more. From the viewpoint of easy pulling during film formation, the content of the ethylene-α-olefin copolymer (A) is 80% by weight or less, more preferably 70% by weight or less.

  Examples of the method of blending the ethylene-α-olefin copolymer (A) and the ethylene-α-olefin copolymer (B) of the polyethylene resin composition used in the present invention include a Henschel mixer, a tumbler mixer, and the like. Examples include dry blending using a rotary blender; melt blending using a single screw extruder, twin screw extruder, Banbury mixer, hot roll, and the like.

In the present invention, the above-described resin composition and additives can be used together as necessary.
Examples of the additive include antioxidants, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, dripping agents, pigments, fillers, oxygen absorbers, and release agents.

  Examples of the film forming method include an extrusion forming method such as an inflation forming method and a T-die forming method, and a calendar forming method.

  The film for stretch labels of the present invention may be a single layer film or a multilayer film. In the case of a multilayer film, all the layers each contain 50% by weight to 90% by weight of the ethylene-α-olefin copolymer (A) of the present invention, and the ethylene-α-olefin copolymer (B). It is preferable to contain 10 weight% or more and 50 weight% or less.

  The film for stretch labels using the polyethylene resin composition of the present invention is suitable for use as a stretch label attached to a plastic bottle.

Hereinafter, the present invention will be described with reference to examples and comparative examples. The present invention is not limited to the following examples.
The physical properties in Examples and Comparative Examples were measured according to the following methods.

[Physical properties of polymer]
(1) Melt flow rate (MFR, unit: g / 10 minutes)
According to the method defined in JIS K7210-1995, the measurement was performed by the A method under the conditions of a load of 21.18 N and a temperature of 190 ° C.

(2) Density (Unit: Kg / m ³ )
It measured according to the method prescribed | regulated to A method among JISK7112-1980. The sample was annealed according to JIS K6760-1995.

(3) Molecular weight distribution (Mw / Mn)
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 (7), and the molecular weight distribution (Mw / Mn) was determined.
(1) Equipment: Waters 150C manufactured by Water
(2) Separation column: TOSOH TSKgelGMH-HT
(3) Measurement temperature: 145 ° C
(4) Carrier: Orthodichlorobenzene
(5) Flow rate: 1.0 mL / min
(6) Injection volume: 500 μL
(7) Detector: Differential refraction

(4) Flow activation energy (Ea, unit: kJ / mol)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), a melt complex viscosity-angular frequency curve at 130 ° C., 150 ° C., 170 ° C. and 190 ° C. was measured under the following measurement conditions. From the obtained melt complex viscosity-angular frequency curve, calculation software Rhios V. 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 to 100 rad / sec Measurement atmosphere: Under nitrogen [physical properties of the film]

(5) Residual strain (unit:%)
The film flow direction during film formation was defined as the MD direction, and the direction perpendicular to the MD direction was defined as the TD direction. A strip test piece having a length of 110 mm and a width of 15 mm was taken so that the longitudinal direction was the TD direction and the width direction was the MD direction, and the distance between the marked lines was 50 mm. A test piece is attached to a tensile tester at a distance of 50 mm between chucks, pulled at a speed of 300 mm / min, and deformed until the strain becomes 25% (until the distance between chucks reaches 62.5 mm). Immediately after that, the distance T (mm) between the marked lines was measured under the condition of 23 ° C., and the residual strain was determined by the following formula. It can be said that the smaller this value, the better the self-stretching property.
Residual strain = {(T-50) ÷ 50} × 100

(6) Rigidity (1% SM) (Unit: MPa)
Strip test specimens having a length of 0.12 m and a width of 0.02 m were taken so that the longitudinal direction would be the MD direction or TD direction during film formation, and 0.06 m between chucks using the test specimens. A tensile test was performed under the condition of a tensile speed of 5 mm / min, and a stress-strain curve was measured. From the stress-strain curve, a load at 1% elongation (unit: N) was determined, and 1% SM was calculated from the following formula. It can be said that the greater the value of 1% SM, the better the rigidity.
1% SM = [F / (t × l)] / [s / L0] / 106
F: Load at 1% elongation (unit: N)
t: Test piece thickness (unit: m)
l: Specimen width (Unit: m, 0.02)
L0: Distance between chucks (Unit: m, 0.06)
s: 1% strain (unit: m, 0.0006)

(7) Pressure of molten resin in extruder during film formation (unit: MPa)
The pressure of the molten resin in the extruder during film formation was measured by a resin pressure sensor provided in a T-die film molding machine manufactured by SHI Modern Machinery Co., Ltd. It can be said that the smaller this value is, the smaller the extrusion load of the resin during film formation is, and the better the workability is.

[Example 1]
(1) Preparation of solid catalyst component (X) Silica (Sypolol 948 manufactured by Debison Co., Ltd .; 50% volume average particle size = 55 μm; fine) heat-treated at 300 ° C. under nitrogen flow in a reactor equipped with a nitrogen-replaced stirrer (Pore volume = 1.67 ml / g; specific surface area = 325 m ² / g) 2.8 kg and 24 kg of toluene were added and stirred. Then, after cooling the reactor 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 kept at 5 ° C. The solution was added dropwise over 30 minutes. After completion of dropping, the components in the reactor were 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 the washed solid product to form a slurry, which was allowed to stand overnight.

To the slurry obtained above, 1.73 kg of diethylzinc in hexane (diethylzinc concentration: 50% by weight) and 1.02 kg of hexane were added and stirred to obtain a mixture. Then, after cooling the mixture to 5 ° C., a mixed solution of 0.78 kg of 3,4,5-trifluorophenol and 1.44 kg of toluene was added dropwise over 60 minutes while keeping the temperature of the reactor at 5 ° C. After completion of dropping, the components in the reactor were stirred at 5 ° C. for 1 hour, then heated to 40 ° C. and stirred at 40 ° C. for 1 hour. Thereafter, the components in the reactor were cooled to 22 ° C., and 0.11 kg of H ₂ O was added dropwise over 1.5 hours while maintaining the reactor temperature at 22 ° C. After completion of dropping, the components in the reactor were stirred at 22 ° C. for 1.5 hours, then heated to 40 ° C., stirred at 40 ° C. for 2 hours, further heated to 80 ° C., and then heated at 80 ° C. for 2 hours. Stir to obtain a slurry. At room temperature, the supernatant of the slurry was withdrawn until the amount of slurry reached 16 L, 11.6 kg of toluene was added, and then the temperature was raised to 95 ° C. and stirred for 4 hours to obtain a slurry. The supernatant liquid was extracted from the slurry 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, the washed solid component was dried to obtain a solid catalyst component (X).

(2) Preparation of prepolymerization catalyst component 80 liters of butane was charged into an autoclave with a stirrer having an internal volume of 210 liters that had been previously purged with nitrogen, and then 109 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide was charged into the autoclave. The temperature was raised to 50 ° C., and the components in the autoclave were stirred for 2 hours. Next, after the temperature of the autoclave is lowered to 30 ° C. and the system is stabilized, ethylene is charged in an amount of 0.03 MPa at the gas phase pressure in the autoclave, and 0.7 kg of the solid catalyst component (X) is added, followed by triisobutyl. 158 mmol of aluminum was added to initiate ethylene polymerization. After 30 minutes while continuously supplying ethylene at 0.7 kg / Hr, the temperature of the autoclave was increased to 50 ° C., and ethylene and hydrogen were respectively 3.5 kg / Hr and 10.2 liters (normal temperature and normal pressure volume). ) / Hr was continuously fed to polymerize ethylene for a total of 4 hours. After the polymerization was completed, ethylene, butane, hydrogen gas and the like were purged, and the remaining solid was vacuum dried at room temperature to obtain a prepolymerized catalyst component in which 15 g of polyethylene was prepolymerized per 1 g of the solid catalyst component (X). .

(3) Production of ethylene-1-hexene copolymer (A-1) Using the above prepolymerization catalyst component, ethylene and 1-hexene are copolymerized in a continuous fluidized bed gas phase polymerization apparatus, and the copolymer is obtained. I got a powder. The polymerization conditions were a polymerization temperature of 80 ° C., a polymerization pressure of 2 MPa, a hydrogen molar ratio to ethylene of 0.4%, and a 1-hexene molar ratio to the total of ethylene and 1-hexene of 1.6%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Further, the prepolymerization catalyst component and triisobutylaluminum were continuously supplied, and the total powder weight of the fluidized bed was maintained at 80 kg. The average polymerization time was 4 hours. The obtained copolymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel), feed rate 50 kg / hr, screw rotation speed 450 rpm, gate opening 50%, suction pressure 0.1 MPa, resin temperature 200-230. By granulating under the condition of ° C., an ethylene-1-hexene copolymer (A-1) was obtained. Table 1 shows the physical properties of the obtained copolymer.

(4) Preparation of mixture C-1-a for both outer layers A-1 60.6% by weight and Sumikasen E FV401 (ethylene-α-olefin copolymer, Ea = 35 kJ / mol, MFR = 4 g / 10 min) , Density = 905 kg / m ³ , Mw / Mn = 2.8, MFRR = 18.3, manufactured by Sumitomo Chemical Co., Ltd., hereinafter abbreviated as B-1. Physical properties are shown in Table 2.) 22.8 weight %, Sumikacene E FV402 (ethylene-α-olefin copolymer, Ea = 32 kJ / mol, MFR = 4 g / 10 min, density = 913 kg / m ³ , Mw / Mn = 3.2, MFRR = 17.2, Sumitomo Chemical Co., Ltd., hereinafter abbreviated as B-2. Physical properties are shown in Table 2.) 16.6 wt% and the following additives were pellet blended in a tumbler blender, and mixture C-1-a Got. The additive used for the mixture C-1-a was Elca, which is a lubricant, when the total amount of the A-1, B-1, and B-2 contained in the mixture C-1-a was 100 parts by weight. 0.06 part by weight of acid amide (hereinafter abbreviated as SA-1), 0.05 part by weight of ethylene bisoleic acid amide (hereinafter abbreviated as SA-2) as a lubricant, and an average as an antiblocking agent Synthetic aluminosilicate particles having a particle diameter of 5 μm (hereinafter abbreviated as AB-1) 0.7 parts by weight, Sumitizer GP (manufactured by Sumitomo Chemical Co., Ltd., hereinafter abbreviated as AO-1). .) 0.1 parts by weight. The composition of the obtained mixture C-1-a is shown in Table 3.

(5) Preparation of mixture C-1-b for intermediate layer A-1 60.1% by weight, B-1 29.7% by weight, B-2 10.2% by weight, and the following additives Was pellet-blended with a tumbler blender to obtain a mixture C-1-b. The additive used for the mixture C-1-b was SA-10 when the total amount of the A-1, B-1, and B-2 contained in the mixture C-1-b was 100 parts by weight. 0.06 part by weight, 0.05 part by weight of SA-2, and 0.1 part by weight of AO-1. The composition of the obtained mixture C-1-b is shown in Table 3.

(6) Film processing A multilayer film was produced using a T-die film molding machine manufactured by SHI Modern Machinery Co., Ltd. using the mixture C-1-a and the mixture C-1-b. A sintered filter (MFF NF06 manufactured by Nippon Seisen Co., Ltd.) is placed on the breaker plate (φ51 mm) of the extruder having a diameter of 50 mm and L / D of 32 (L is the length of the cylinder of the extruder, D is the diameter of the cylinder of the extruder). , Filtration diameter: 10 μm) was set in a configuration sandwiched between 80 mesh wire nets. Note that three extruders are provided. The mixture C-1-a is introduced into the extruder for the outer layer 1 and the extruder for the outer layer 2, respectively, and the mixture C-1-b is introduced into the extruder for the intermediate layer and melted at 230 ° C., respectively. After kneading, it is supplied to a T die (600 mm width) adjusted to 230 ° C. through the sintered filter, and the outer layer 1C-1-a / intermediate layer C-1-b / outer layer 2C-1-a from the T die. Were extruded at a layer ratio (thickness ratio) of 1/2/1, respectively, and then cooled and solidified by drawing with a chill roll at 50 ° C. to obtain a film having a thickness of 80 μm. Table 3 shows the physical property evaluation results of the obtained film.

[Example 2]
(1) Preparation of mixture C-2-a for both outer layers Mixture C-1 for both outer layers of Example 1 except that A-1 is 80.8 wt% and B-1 is 2.6 wt%. The mixture was blended in the same manner as -a to obtain a mixture C-2-a. The composition of the obtained mixture C-2-a is shown in Table 3.

(2) Preparation of intermediate layer mixture C-2-b Intermediate layer mixture C-1- of Example 1 except that A-1 was 80.2 wt% and B-1 was 9.6 wt% The mixture was blended in the same manner as b to obtain a mixture C-2-b. The composition of the obtained mixture C-2-b is shown in Table 3.

(3) Film processing A film having a thickness of 80 μm was obtained in the same manner as in Example 1 using the mixture C-2-a and the mixture C-2-b. Table 3 shows the physical property evaluation results of the obtained film.

[Comparative Example 1]
(1) Preparation of mixture C-3-a for both outer layers Mixture C-1- for both outer layers of Example 1 except that A-1 is 30.3% by weight and B-1 is 53.1% by weight. Blending was carried out in the same manner as a to obtain a mixture C-3-a. The composition of the obtained mixture C-3-a is shown in Table 3.

(2) Preparation of intermediate layer mixture C-3-b Intermediate layer mixture C-1 of Example 1 except that A-1 was 30.1 wt% and B-1 was 59.7 wt% The mixture was blended in the same manner as -b to obtain a mixture C-3-b. The composition of the obtained mixture C-3-b is shown in Table 3.

(3) Film processing A film having a thickness of 80 μm was obtained in the same manner as in Example 1 using the mixture C-3-a and the mixture C-3-b. Table 3 shows the physical property evaluation results of the obtained film.

[Comparative Example 2]
(1) Production of ethylene-1-hexene copolymer (A-2) Using the prepolymerization catalyst component described in Example 1, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus. Thus, a copolymer powder was obtained. The hydrogen molar ratio to ethylene was 1.59%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.25%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Further, the prepolymerization catalyst component and triisobutylaluminum were continuously supplied, and the total powder weight of the fluidized bed was maintained at 80 kg. The average polymerization time was 4 hours. The obtained copolymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel), feed rate 50 kg / hr, screw rotation speed 450 rpm, gate opening 50%, suction pressure 0.1 MPa, resin temperature 200-230. By granulating under the condition of ° C., an ethylene-1-hexene copolymer (A-2) was obtained. Table 1 shows the physical properties of the obtained copolymer.
(2) Preparation of mixture C-4-a for both outer layers The above A-2 61.8 wt%, B-2 38.2 wt%, and the following additives were pellet blended in a tumbler blender, A mixture C-4-a was obtained. The additive used for the mixture C-4-a was 0.06 parts by weight of SA-1 when the total amount of the A-2 and B-2 contained in the mixture C-4-a was 100 parts by weight. SA-2 0.05 parts by weight, AB-1 0.7 parts by weight, and AO-1 0.1 parts by weight. The composition of the obtained mixture C-4-a is shown in Table 3.

(3) Preparation of mixture C-4-b for intermediate layer The above A-2 61.1 wt%, B-2 38.9 wt%, and the following additives were pellet blended in a tumbler blender, A mixture C-4-b was obtained. The additive used for the mixture C-4-b was 0.06 parts by weight of SA-1 when the total amount of the A-2 and B-2 contained in the mixture C-4-b was 100 parts by weight. SA-2 0.05 parts by weight and AO-1 0.1 parts by weight. The composition of the obtained mixture C-4-b is shown in Table 3.

(4) Processing of film A film having a thickness of 80 μm was obtained in the same manner as in Example 1 using the mixture C-4-a and the mixture C-4-b. Table 3 shows the physical property evaluation results of the obtained film.

Claims (1)

Ethylene-α- which includes a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies all of the following requirements (a1), (a2) and (a3) Olefin copolymer (A) 50 wt% or more and 90 wt% or less,
Ethylene-α- which includes a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and satisfies all of the following requirements (b1), (b2) and (b3) Olefin copolymer (B) 10 wt% or more and 50 wt% or less (however, the total amount of ethylene-α-olefin copolymer (A) and ethylene-α-olefin copolymer (B) is 100 wt%) %) Stretch label film.
Ethylene-α-olefin copolymer (A)
(A1) Flow activation energy is 40 kJ / mol or more.
(A2) The molecular weight distribution is 5 or more and 25 or less.
(A3) The melt flow rate is 0.9 g / 10 min or more and 3 g / 10 min or less.
Ethylene-α-olefin copolymer (B)
(B1) Flow activation energy is 35 kJ / mol or less.
(B2) The melt flow rate is 2 g / 10 min or more and 10 g / 10 min or less.
(B3) density 900 kg / ^{m 3} or more 915 kg / ^{m 3} that less.