JP5919768B2 - Film with excellent blocking resistance - Google Patents

Description

  The present invention provides a film that can be stably formed without adding a high-pressure forensic density polyethylene and an antiblocking agent, and further has excellent blocking resistance.

  Polyolefin-based films made of polyethylene-based resins, polypropylene-based resins, and the like are widely used as various packaging materials.

  In general, it is known that high-pressure low-density polyethylene (hereinafter referred to as LDPE) has a high melt tension (hereinafter referred to as MS) and is excellent in film formation stability when a film is formed. However, since LDPE has a large flow activation energy (hereinafter referred to as Ea) and a large temperature dependence of melt viscosity, in actual film forming, it has a high MS only in a specific processing temperature range. It was necessary to select a processing machine suitable for the polymer. Moreover, it was inferior to mechanical strength, heat resistance, and weather resistance, and the improvement was calculated | required.

  On the other hand, an ethylene / α-olefin copolymer called linear low-density polyethylene (hereinafter referred to as LLDPE) is manufactured with a Ziegler type catalyst or a metallocene catalyst, and has higher strength and toughness than LDPE. Although widely used in the field, although Ea is small and melt tension is stable in a wide temperature range, the absolute value of melt tension is small, so there is a problem that molding stability at the time of film molding is lacking. ing.

  As an ethylene polymer with improved moldability, for example, a specific metallocene catalyst is used, and an ethylene-α-olefin copolymer having a long chain branch obtained under specific polymerization conditions (see, for example, Patent Document 1). ), An ethylene-α-olefin copolymer obtained with a specific metallocene catalyst and having an Ea of 60 kJ / mol or more (see, for example, Patent Document 2).

  Patent Document 3 proposes an ethylene-α-olefin copolymer obtained with a specific metallocene catalyst and having an Ea of 35 kJ / mol or more.

  Elution temperature-elution determined by continuous temperature rising elution fractionation method (TREF) despite the narrow molecular weight distribution of 1.5-4.5 obtained under specific polymerization conditions using a specific metallocene catalyst In the curve, an ethylene-α-olefin copolymer having a broad distribution on the low temperature side and a composition distribution having one peak between 85 ° C. and 100 ° C. (see, for example, Patent Document 3). ), Etc. have been proposed. Also, an ethylene polymer produced using a Cr-based catalyst is known as an ethylene-based polymer having a low Ea, a wide composition distribution, and a high MS, and having stable processability in a wide range of molding processing temperatures. ing.

  However, since the ethylene-based copolymers proposed in Patent Documents 1 and 2 have large Ea and the temperature dependence of the melt viscosity is large like LDPE, it is necessary to strictly control the temperature in the molding process. In addition, since the composition distribution is very sharp, the heat seal temperature is higher than that of LDPE having a wide composition distribution containing a relatively large amount of low-melting components when compared at the same density, and is inferior in heat resistance. Had.

  Further, since the ethylene-α-olefin copolymer proposed in Patent Document 3 has a large Ea and a large temperature dependence of melt viscosity like LDPE, it is necessary to strictly control the temperature in the molding process. . In addition, since the haze of the film is small and the surface is smooth, there is a problem that the film is easily blocked when the films are stacked.

  Further, the ethylene-α-olefin copolymer proposed in Patent Document 4 has a narrow molecular weight distribution of 1.5 to 4.5, and has a low temperature fusion property (seal strength) even when the composition distribution is expanded. It had the problem of being insufficient. Furthermore, in the ethylene polymer produced using a Cr-based catalyst, in our study, the terminal vinyl group is present in the ethylene polymer in an amount of 0.3 or more per 1,000 carbon atoms. There is a problem in thermal stability such as yellowing.

  As a countermeasure against blocking, it is known to add an anti-blocking agent made of an inorganic compound such as silica or zeolite, or a slip agent made of a fatty acid amide. However, the addition of an antiblocking agent or slip has a problem that the cleanliness of the film is impaired.

  Thus, with the conventionally known technique, a film can be stably formed, and a film having excellent blocking resistance cannot be obtained without adding an antiblocking agent.

US Pat. No. 5,272,236 Japanese Patent Laid-Open No. 2004-292772 JP 2010-116567 A JP 09-25317 A

  The present invention has been made in view of the above situation, and can stably form a film without mixing a high-pressure method low-density polyethylene, and can be blocked without adding an antiblocking agent. The object is to provide an excellent film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the problems can be solved by using a specific ethylene polymer, and have completed the present invention.

That is, the present invention comprises a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms, and satisfies the following requirements (A) to (H). And a film characterized by satisfying the following requirements (I) to (J).
(A) Density measured by JIS K6922-1 (1998) is 910 kg / m ³ or more and 940 kg / m ³ or less (B) Melt mass flow rate (MFR) measured by JIS K6922-1 (1998) is 0 0.1-20 g / 10 min (C) 0.2 or less terminal vinyl per 1,000 carbon atoms (D) Melt tension at 160 ° C. [MS ₁₆₀ (mN)] measured by a capillary viscometer of 40 or more 150 or less (E) The melt tension MS _{160 at} 160 ° C. measured by a capillary viscometer and the melt tension [MS ₁₉₀ (mN)] at 190 ° C. satisfy the following formula (1) MS ₁₆₀ / MS ₁₉₀ <1.8 (1 )
(F) Flow activation energy [Ea (kJ / mol)] is 30 or more and less than 50 (G) Multiple peaks are present in the elution temperature-elution amount curve obtained by temperature rising elution fractionation (H) Gel permeation The ratio of the z-average molecular weight to the weight-average molecular weight (Mz / Mw) and the ratio of the weight-average molecular weight to the number-average molecular weight (Mz / Mw) / (Mw / Mn), which were determined by the measurement of the association chromatography (GPC) Greater than 0.9 (I) Haze [Hz (%)] measured in accordance with JIS K7105 (1981) is 20% or more (J) Silica, talc, zeolite, mica, carbon, calcium carbonate, magnesium carbonate Furthermore, it is related with the film of Claim 1 manufactured on the conditions which satisfy | fill the following requirements (K)-(M).
(K) Created by air-cooled inflation molding method (L) Film thickness is 10 μm or more and 300 μm or less (M) Shear rate when molten resin is extruded from die is 30 s ⁻¹ or more and 1,500 s ⁻¹ or less The present invention relates to a multilayer film including a film as an outermost layer.

  The present invention is described in detail below.

  Examples of the α-olefin having 3 to 8 carbon atoms used for the ethylene polymer constituting the film of the present invention include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 3-methyl-1-butene. Alternatively, an α-olefin such as vinylcycloalkane, a diene such as butadiene or 1,4-hexadiene can be exemplified. Two or more of these olefins can be mixed and used.

The density of the ethylene polymer constituting the film of the present invention measured by JIS K6922-1 (1998) is 910 kg / m ³ or more and 940 kg / m ³ or less. When the density is lower than 910 kg / m ³ , the flexibility of the film is improved, but the rigidity is insufficient and the workability of secondary processing may be reduced. On the other hand, if the density is higher than 940 kg / m ³ , the ethylene / α-olefin copolymer crystals are difficult to melt and the molding process speed must be reduced, which is not preferable because of poor productivity. Furthermore, when the density is higher than this range, the rigidity of the film increases, but on the other hand, the flexibility is lowered, which is not preferable.

  The melt mass flow rate (hereinafter referred to as MFR) measured by JIS K6922-1 (1998) of the ethylene polymer constituting the film of the present invention is in the range of 0.1 to 20 g / 10 min, preferably The range is 0.1 to 10 g / 10 minutes, more preferably 0.2 to 7 g / 10 minutes. If the MFR is less than 0.1 g / 10 min, the extrusion load when extruding the ethylene / α-olefin copolymer is increased, which is not preferable because it is necessary to reduce the productivity. Moreover, when MFR exceeds 20 g / 10min, melt tension will become low, and since it is inferior to the stability at the time of film forming and the intensity | strength of a film falls, it is unpreferable.

  When the ethylene polymer constituting the film of the present invention has 0.01 to 0.2 long-chain branches having 6 or more carbon atoms per 1000 carbon atoms, film-forming stability and high-speed production are achieved. It is preferable because both film properties can be achieved.

  The ethylene polymer constituting the film of the present invention has a terminal vinyl number of not more than 0.2 per 1,000 carbon atoms, particularly preferably not more than 0.1. Here, an ethylene polymer having a terminal vinyl number exceeding 0.2 per 1,000 carbon atoms causes a problem of thermal deterioration, particularly yellowing, during molding.

The number of terminal vinyls referred to in the present invention is, for example, 4000 cm using a film prepared by hot pressing an ethylene polymer using a Fourier transform infrared spectrophotometer (FT-IR) and then cooling with ice. It can be calculated using the following equation based on the result of measurement in the range of ^{−1 to} 400 cm ⁻¹ .

Number of terminal vinyls per 1,000 carbon atoms (pieces / 1000 C) = a × A / L / d
(In the formula, a represents an absorptivity coefficient, A represents an absorbance of 909 cm ⁻¹ attributed to terminal vinyl, L represents a film thickness, and d represents a density.)
The absorptivity coefficient of a can be determined from a calibration curve prepared using a sample in which the number of terminal vinyls per 1,000 carbon atoms is confirmed from ¹ H-NMR measurement. 1H-NMR measurement was performed at 130 ° C. in a mixed solvent of deuterated benzene and o-dichlorobenzene using a nuclear magnetic resonance measuring apparatus (trade name GSX400, manufactured by JEOL Ltd.). The number of terminal vinyls per 1,000 carbon atoms was calculated from the integral ratio of the peak attributed to methylene and the peak attributed to terminal vinyl. With respect to each peak, tetramethylsilane was used as a standard (0 ppm), and a peak with a chemical shift of 1.3 ppm was attributed to methylene, and a peak with 4.8 to 5.0 ppm was attributed to terminal vinyl.

The ethylene polymer constituting the film of the present invention has a melt tension measured at 160 ° C. (hereinafter referred to as MS ₁₆₀ ) of 40 mN or more and 150 mN or less. If MS ₁₆₀ is less than 40 mN, the stability during film formation is inferior, which is not preferable. On the other hand, when MS ₁₆₀ exceeds 150 mN, the stretchability is insufficient and the film-forming property at high speed is poor.

The MS ₁₆₀ referred to in the present invention uses an orifice having a length of 8 mm and a diameter of 2.095 mm, an inflow angle of 90 °, a shear rate of 10.8 s ⁻¹ , and a stretching ratio of 47. It can be measured at 160 ° C. However, when the maximum stretch ratio was less than 47, the value measured at the highest stretch ratio that did not break was MS ₁₆₀ .

The relationship between the melt tension [MS ₁₉₀ (mN)] (hereinafter referred to as MS ₁₉₀ ) measured at 190 ° C. and MS ₁₆₀ satisfies the following formula (1) in the ethylene polymer constituting the film of the present invention. In particular, it is preferable that the following formula (1 ′) is satisfied. Here, when MS ₁₆₀ / MS ₁₉₀ is an ethylene polymer of 1.8 or more, the melt tension due to the molding process temperature changes greatly, so that it is necessary to strictly adjust the molding process temperature. Becomes narrow and becomes an ethylene-based resin having inferior moldability.

MS ₁₆₀ / MS ₁₉₀ <1.8 (1)
MS ₁₆₀ / MS ₁₉₀ <1.7 (1 ′)
The ethylene polymer constituting the film of the present invention has a flow activation energy [Ea (kJ / mol)] (hereinafter referred to as Ea) of 30 or more and less than 50. If Ea is less than 30 kJ / mol, a problem arises in workability when it is used during film formation. On the other hand, if Ea is 50 kJ / mol or more, the temperature dependence of the melt viscosity is large, and it is necessary to strictly adjust the molding processing temperature, which leads to a problem that the moldable range is narrowed.

  In addition, Ea said by this invention can be calculated | required by substituting the shift factor obtained by the dynamic viscoelasticity measurement of 160 to 230 degreeC, for example to an Arrhenius equation.

  The ethylene polymer constituting the film of the present invention has a plurality of peaks in an elution temperature-elution amount curve obtained by a continuous temperature rising elution fractionation method (hereinafter referred to as TREF), and particularly has a melting point. It is preferable that the peak on the high temperature side exists between 85 ° C. and 100 ° C. because the heat resistance and rigidity of the molded body are improved because the degree of crystallinity increases. Moreover, it is preferable that the peak on the low temperature side exists between 65 ° C. and 80 ° C. because it is excellent in low temperature heat sealing characteristics when formed into a molded body. Since the ethylene polymer constituting the film of the present invention has a wide composition distribution, the elution temperature-elution amount curve has two peaks, and an ethylene / α-olefin copolymer obtained by a conventional metallocene catalyst and Are different.

  The ethylene polymer constituting the film of the present invention preferably has an n-heptane extraction amount of less than 0.2% by weight at 50 ° C. because the film is excellent in low-temperature heat sealability.

  Since the ethylene polymer constituting the film of the present invention can obtain a molded product particularly excellent in mechanical strength, the weight average molecular weight (hereinafter referred to as Mw) and the number average molecular weight (hereinafter referred to as Mn). The ratio (Mw / Mn) is preferably 4.5 or more and 7.5 or less, and particularly preferably 5.0 or more and 7.0 or less. The Mw and Mn referred to in the present invention can be calculated as standard polyethylene conversion values from an elution curve measured by gel permeation chromatography (hereinafter referred to as GPC).

The ethylene polymer constituting the film of the present invention has a z-average molecular weight (hereinafter referred to as Mz) measured by GPC and a ratio of Mw Mz / Mw to Mw / Mn ( Mz / Mw ) / (Mw / Mn) is less than 0.9. When ( Mz / Mw ) / (Mw / Mn) is greater than 0.9, the proportion of components having a very high molecular weight increases, so the melt viscosity at the time of film formation increases and high-speed productivity decreases, which is preferable. Absent.

  The method for producing the ethylene polymer constituting the film of the present invention is not limited, and can be produced by a method using a Ziegler catalyst, a method using a Phillips catalyst, a method using a metallocene catalyst, etc., but a method using a metallocene catalyst It is preferable to manufacture by.

  When producing an ethylene-based polymer using a metallocene catalyst, the metallocene catalyst to be used has a metallocene complex, an activation co-catalyst, and, if necessary, an organoaluminum compound as constituent components. It is preferable to carry out the copolymerization of the macromonomer with ethylene and an olefin having 3 to 6 carbon atoms and the copolymerization with ethylene and an olefin having 3 to 6 carbon atoms with a specific metallocene catalyst simultaneously with the synthesis of the macromonomer. . Here, the macromonomer is an olefin polymer having a vinyl group at the terminal, and is an ethylene copolymer having a vinyl group at the terminal obtained by copolymerizing ethylene and an olefin having 3 to 6 carbon atoms.

  The number average molecular weight (Mn) in terms of linear polyethylene of the macromonomer is preferably 2,000 or more, more preferably 5,000 or more, and most preferably 1,000,000 or more. The weight average molecular weight (Mw) in terms of linear polyethylene is 4,000 or more, preferably 10,000 or more, more preferably more than 15,000. Increasing the molecular weight of the macromonomer increases the length of the long chain branch introduced into the ethylene polymer and improves the melt tension.

  Specific metallocene catalysts for synthesizing macromonomers include metallocene complexes, non-bridged bis (indenyl) zirconium complexes, non-bridged bis (cyclopentadienyl) zirconium complexes, bridged bis (cyclopentadienyl) zirconium complexes, Alternatively, a catalyst using a bridged (cyclopentadienyl) (indenyl) zirconium complex (hereinafter referred to as component (j)) is preferable.

  Specific examples of the component (j) include, for example, bis (indenyl) zirconium dichloride, bis (cyclopentadienyl) zirconium dichloride, 1,1,3,3-tetramethyldisiloxane-1,3-diyl-bis (cyclopenta). Dienyl) zirconium dichloride, 1,1-dimethyl-1-silaethane-1,2-diyl-bis (cyclopentadienyl) zirconium dichloride, propane-1,3-diyl-bis (cyclopentadienyl) zirconium dichloride, Dimethylsilanediyl (cyclopentadienyl) (indenyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (2-methylindenyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (4,7-dimethyl Ndenyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (2,4,7-trimethylindenyl) zirconium dichloride and the like, and dimethyl, diethyl, dihydro, diphenyl and dibenzyl of the above transition metal compounds However, it is not limited to these examples.

  In addition, specific metallocene catalysts that perform macromonomer copolymerization at the same time as the synthesis of the macromonomer include a metallocene complex, a bridged (cyclopentadienyl) (fluorenyl) zirconium complex or a bridged (indenyl) (fluorenyl) zirconium complex. A catalyst using (hereinafter referred to as component (k)) is preferred.

  Specific examples of component (k) include, for example, diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-trimethylsilyl-1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, Diphenylmethylene (1-cyclopentadienyl) (2,7-dimethyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium Dichloride, isopropylidene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, isopropylidene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenyl Randiyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, dimethylsilanediyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-indenyl) (9-fluorenyl) zirconium dichloride Diphenylmethylene (2-phenyl-1-indenyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, etc. Examples thereof include dimethyl, diethyl, dihydro, diphenyl, and dibenzyl isomers of dichloride and the above transition metal compounds. Moreover, although the compound which substituted the zirconium atom of the said transition metal compound with the titanium atom or the hafnium atom can also be illustrated, it is not limited to these.

There is no restriction | limiting in particular in the quantity of the component (k) with respect to a component (j), It is preferable that it is 0.0001-100 times mole, Most preferably, it is 0.001-10 times mole.
The activation co-catalyst used as a component of the metallocene catalyst is a metallocene complex or a compound that plays a role in converting a reaction product of a metallocene complex and an organoaluminum compound into an active species capable of olefin polymerization. It is preferable that it is a compound which produces | generates a reactive compound, and the produced | generated cationic compound acts as a polymerization active seed | species which can superpose | polymerize an olefin. An activation co-catalyst is a compound that provides a compound that, after forming a polymerization active species, coordinates weakly or interacts with the generated cationic compound, but does not react directly with the active species.

  Specific examples of the activation promoter include alkylaluminoxanes such as methylaluminoxane, silica gel-supported alkylaluminoxanes, tris (fluorinated aryl) borons such as tris (pentafluoreophenyl) boron, N, N-dimethylammonium-tetrakis ( Examples thereof include boron compounds such as tetrakis (fluorinated aryl) boron salts such as pentafluorophenyl) boron, silica gel-supported materials thereof, clay minerals, clay minerals treated with organic compounds, and the like. Among these, it is preferable to use a clay mineral treated with an organic compound.

  When a clay mineral treated with an organic compound is used as the activation promoter, the clay mineral used is preferably a clay mineral belonging to the smectite group, and specific examples include montmorillonite, beidellite, saponite, hectorite and the like. It is also possible to use a mixture of a plurality of these clay minerals.

  The organic compound treatment means introducing an organic ion between clay mineral layers to form an ionic complex. Examples of the organic compound used in the organic compound treatment include N, N-dimethyl-n-octadecylamine hydrochloride, N, N-dimethyl-n-eicosylamine hydrochloride, N, N-dimethyl-n-docosylamine hydrochloride, N, N-dimethyloleylamine hydrochloride, N, N-dimethylbehenylamine hydrochloride, N-methyl-bis (n-octadecyl) amine hydrochloride, N-methyl-bis (n-eicosyl) amine hydrochloride, N-methyl -Alkylammonium salts such as dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, N, N-dimethylaniline hydrochloride can be exemplified.

The metallocene catalyst is a method of reacting a mixture of component (j) and component (k) with an activation promoter, a method of reacting component (j) and the activation promoter, and then reacting component (k), Although it prepares by the method of making (j) and component (k) react separately, there is no restriction | limiting in particular in the preparation method of a metallocene catalyst.
As the metallocene catalyst, an alkylaluminum such as triethylaluminum or triisobutylaluminum may be used as necessary for the activation of the metallocene complex and the removal of impurities in the solvent during the preparation of the catalyst.

  When the ethylene polymer constituting the extruded film of the present invention is produced, it is preferably carried out at a polymerization temperature of −100 to 120 ° C., preferably 20 to 120 ° C. in view of productivity, and more preferably 60 to 120. It is preferable to carry out in the range of ° C. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa. The polymerizable monomer is ethylene and an α-olefin having 3 to 6 carbon atoms, and the supply ratio of ethylene and the α-olefin having 3 to 6 carbon atoms is ethylene / α-olefin having 3 to 6 carbon atoms ( A feed ratio of 1 to 200, preferably 3 to 100, and more preferably 5 to 50 can be used. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. In addition, the ethylene copolymer can be obtained by separating and recovering from the polymerization solvent by a conventionally known method after the completion of the polymerization and drying. Polymerization can be carried out in a slurry state, a solution state, or a gas phase state. In particular, when the polymerization is performed in a slurry state, an ethylene-based copolymer having a powder particle shape is efficiently and stably produced. Can do.

  The number of long chain branches of the ethylene polymer constituting the film of the present invention can be increased by increasing the number of terminal vinyls of the macromonomer. The number of terminal vinyls of the macromonomer can be controlled by selecting a metallocene compound for synthesizing the macromonomer. For example, it can be increased by changing the non-bridged metallocene compound to a bridged metallocene compound.

  Mw / Mn of the ethylene polymer constituting the film of the present invention can be increased by decreasing Mn of the macromonomer. The Mn of the macromonomer can be controlled by selecting a metallocene compound for synthesizing the macromonomer. For example, it can be reduced by changing a non-bridged metallocene compound to a bridged metallocene compound.

  The method for producing the film of the present invention is an air-cooled inflation molding method. By producing by this molding method, the obtained film is excellent in productivity and blocking resistance. If the molding method is a water-cooled inflation film molding method or a cast film molding method that is extruded from a T-die, the productivity and blocking resistance are inferior to those of the air-cooled inflation molding method.

  Since the film of the present invention can be used as a container or bag having excellent transparency, the thickness is preferably 10 μm to 300 μm, more preferably 15 μm to 300 μm, and even more preferably 15 to 200 μm.

In the air-cooled inflation molding method, the molten resin is extruded from a circular die to form a film. When the film of the present invention is produced, when the shear rate at which the molten resin is extruded from a circular die is 30 s ⁻¹ or more and 1,500 s ⁻¹ , the blocking resistance, productivity, and film forming stability are excellent. Therefore, it is preferable.

  The film of the present invention has a haze (Hz) of 20% or more measured with a haze meter (model number 300A) manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7105 (1981). Here, if the haze is less than 20%, the obtained film is not preferable because the film is highly transparent and has a smooth surface, and is easily blocked when the films are stacked.

  The ethylene polymer constituting the film of the present invention does not contain inorganic particles generally used as an antiblocking agent such as silica, talc, zeolite, mica, carbon, calcium carbonate, magnesium carbonate. Since these inorganic particles are not compatible with the ethylene-based resin, they may be easily detached from the film surface and may be mixed into the contents, and the inorganic particles may damage the contents when the film is used as a packaging material. That is not preferable.

  In the ethylene polymer constituting the film of the present invention, additives such as an antioxidant, a weather stabilizer, an antistatic agent, a pigment, and a metal stearate are added to the ethylene polymer as necessary, as long as the object of the present invention is not impaired. It may be added. When these additives are added, they are mixed by various known methods such as Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., and then single screw extruder, twin screw extruder, kneader, Banbury mixer, etc. A melt kneading method, granulation or pulverization method, a dry blending method or a blending method using an auto feeder without melting and kneading in advance can be used. Moreover, it can also be used by mixing with other thermoplastic resins.

  Moreover, it is preferable to use a multilayer film containing the film of the present invention as the outermost layer because a film having both functions such as blocking resistance and barrier properties can be obtained.

  In addition, a multilayer film including the film of the present invention is preferable because a film having both functions such as blocking resistance and barrier properties and toughness can be obtained. Here, the multilayer film is exemplified by a two-layer film composed of outer layer / inner layer, a three-layer film composed of outer layer / intermediate layer / inner layer, and a five-layer film composed of outer layer / middle / outer layer / intermediate layer / middle inner layer / inner layer. be able to. As a method for producing a multilayer film, a coextrusion molding method is preferred because of its excellent production cost. Co-extrusion molding methods include a feed port block method in which molten resin is laminated before flowing into the die, an in-die adhesion method in which molten resin is laminated inside the die, and an external die adhesion method in which molten resin is extruded from the die and laminated. Is mentioned. By using the film of the present invention as an outer layer, blocking resistance when the films are stacked can be obtained. Moreover, the film which is excellent in the blocking resistance of the inner surfaces of an inflation film can be obtained by using the film of this invention for an inner layer.

  As a use of the film of this invention, it can use suitably, for example as packaging bags, containers, etc., such as a foodstuff, a pharmaceutical, an industrial chemical, an industrial component, an electronic component, a drink. More specifically, standard bags, heavy bags, rice bags, wrapping films, masking films, cleaning bags, textile packaging bags, industrial parts packaging bags, electronic parts packaging bags, fashion bags, laminating fabrics, sugar bags, oil packaging bags, It can be used for water packaging bags, packaging films for food packaging, stretched tapes, bag-in-boxes, infusion bags, blood bags, medical instrument containers, industrial chemical containers, agricultural materials, and the like.

  By using the film of the present invention, it is possible to stably form a film without mixing high-pressure low-density polyethylene, and it is possible to obtain a film excellent in blocking resistance without adding an antiblocking agent.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

  The evaluation methods for physical properties and processability are shown below.

(1) Melt mass flow rate (MFR)
Measured according to JIS K6922-1 (1998).

(2) Density Measured according to JIS K6922-1 (1998).

(3) Terminal vinyl A Fourier transform infrared spectrophotometer (FT-IR) (manufactured by Perkin Elmer, trade name SPECTRUM ONE) is used to heat press an ethylene polymer, and then a film prepared by cooling with ice is used. It measured in the range of 4000 cm-1-400 cm-1, and computed using the following formula.
Number of terminal vinyls per 1000 carbon atoms (pieces / 1000 C) = a × A / L / d
(In the formula, a represents an absorptivity coefficient, A represents an absorbance of 909 cm −1 attributed to terminal vinyl, L represents a film thickness, and d represents a density. In addition, a represents 1000 carbon atoms from 1H-NMR measurement. The 1H-NMR measurement was performed using a nuclear magnetic resonance measuring apparatus (trade name GSX400, manufactured by JEOL Ltd.), and deuterated benzene and o. -In a mixed solvent of dichlorobenzene at 130 ° C. The number of terminal vinyls per 1000 carbon atoms was calculated from the integral ratio of the peak attributed to methylene and the peak attributed to terminal vinyl. (Based on methylsilane as a reference (0 ppm), a peak with a chemical shift of 1.3 ppm was assigned as methylene and a peak at 4.8-5.0 ppm was attributed to terminal vinyl.)
(4) Melt tension An internal mixer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) added with a heat-resistant stabilizer (manufactured by Ciba Specialty Chemicals, Irganox 1010TM; 1,500 ppm, Irgaphos 168TM; 1,500 ppm) to an ethylene polymer. The product was kneaded for 30 minutes at 190 ° C. and at a rotation speed of 30 rpm under a nitrogen stream using a product name Lab Plast Mill), and adjusted as a measurement sample.

  As for the melt tension, a capillary viscometer (Toyo Seiki Seisakusho, trade name: Capillograph) having a barrel diameter of 9.55 mm was equipped with a die having a length of 8 mm, a diameter of 2.095 mm, and an inflow angle of 90 °. The temperature was set to 130 ° C., the piston lowering speed was set to 10 mm / min, the stretch ratio was set to 47, and the load (mN) required for take-up was taken as the melt tension. When the maximum draw ratio was less than 47, the load (mN) required for taking-up at the highest draw ratio that did not break was taken as the melt tension. The measurement was performed in a constant temperature room set at 23 ° C.

(5) Flow activation energy (Ea)
What added the heat-resistant stabilizer (The product made by Ciba Specialty Chemicals, Irganox 1010TM; 1,500 ppm, Irgafos 168TM; 1,500 ppm) to the ethylene polymer was used as an internal mixer (trade name Lab Plast, manufactured by Toyo Seiki Seisakusho). The sample was kneaded for 30 minutes at 190 ° C. and 30 rpm under a nitrogen stream.

Ea is a shear storage using a disk-disk rheometer (trade name MCR-300, manufactured by Anton Paar Co., Ltd.) at temperatures of 150 ° C., 170 ° C., and 190 ° C. and in an angular velocity range of 0.1 to 100 rad / s. The elastic modulus G ′ and the shear loss elastic modulus G ″ were determined, the shift factor of the horizontal axis at a reference temperature of 150 ° C. was determined, and the calculation was performed according to the following Arrhenius equation.
Viscosity (η _o ) = Aexp (Ea / RT)
In the formula, R is a gas constant. The vertical axis is not moved.

(6) Temperature rising elution fractionation Heat resistance stability is added to the sample, and it is heated and dissolved in o-dichlorobenzene (hereinafter referred to as ODCB) at 135 ° C. to a sample concentration of 0.05% by weight. After 5 ml of this heated solution is injected into a column filled with glass beads, it is cooled to 25 ° C. at a cooling rate of 0.1 ° C./min, and the sample is deposited on the surface of the glass beads. Next, while flowing ODCB through this column at a constant flow rate, the column temperature is raised at a constant rate of 50 ° C./hour to prepare and elute a sample that can be dissolved in the solution at each temperature.

  At this time, the sample concentration in the solvent is continuously detected by the infrared detector with respect to the absorption of methylene for the non-target stretching vibration wave number 2925 cm-1. From this concentration, an elution temperature-elution amount curve can be obtained. TREF analysis is a very small amount of sample, and since it is possible to continuously analyze changes in the elution rate with respect to temperature changes, relatively fine peaks that cannot be detected by the fractionation method can be detected.

(7) Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), and ratio of weight average molecular weight to number average molecular weight (Mw / Mn) It was measured by gel permeation chromatography (hereinafter referred to as GPC). GPC apparatus (trade name HLC-8121 GPC / HT, manufactured by Tosoh Corporation), column (equipped with trade name TSKgel GMHhr-H (20) HT, manufactured by Tosoh Corporation), column temperature 140 ° C., eluent 1, 2, The measurement sample was prepared at a concentration of 1.0 mg / ml and injected by 0.3 ml, and the calibration curve of the molecular weight was calibrated using a polystyrene sample having a known molecular weight. In addition, Mw and Mn were determined as linear polyethylene equivalent values.

(8) Film-forming stability Film-formability was evaluated by producing an air-cooled blown film having a thickness of 40 μm using an air-cooled inflation molding machine (Placo Corporation, model LL-50). The conditions at that time are as follows: extruder cylinder temperature: 180 ° C., extrusion resin temperature: 180 ° C., circular die (lip clearance 2.0 mm), blow ratio 2.0, take-up speed 16 m / min. The width variation of the film at the time of forming the film was measured, and the case where the variation was less than 5 mm per minute was marked as ◯ and the case where the variation was 5 mm or more as x.

(9) Transparency of film (haze)
Based on JIS K7105 (1981), it measured with the Nippon Denshoku Industries Co., Ltd. haze meter (model number 300A).
(10) Blocking resistance Two sheets of the above films are overlapped, pressed with a heat seal tester (manufactured by Tester Sangyo) at 60 ° C. and a pressure of 0.02 MPa for 5 seconds, cut into a width of 15 mm, and measured for peel strength. did. A case where the peel strength was less than 0.2 N was marked with ◯, and a case where the peel strength was higher than that was marked with ×. The seal bar was heated both at the top and bottom.

Synthesis example 1
[Preparation of modified hectorite]
After adding 3 liters of ethanol and 100 ml of 37% concentrated hydrochloric acid to 3 liters of water, 330 g (1.1 mol) of N, N-dimethyl-octadecylamine was added to the resulting solution and heated to 60 ° C. A hydrochloride solution was prepared. 1 kg of hectorite was added to this solution. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 50 L of 60 ° C. water. Then, it dried at 60 degreeC and 10-3 torr for 24 hours, and the modified | denatured hectorite with an average particle diameter of 5.2 micrometers was obtained by grind | pulverizing with a jet mill.

[Preparation of polymerization catalyst (p)]
500 g of the above modified hectorite is suspended in 1.7 liters of hexane, and 5.85 g (20.0 mmol) of bis (cyclopentadienyl) zirconium dichloride and 2.8 liters of a hexane solution (0.714M) of triisobutylaluminum ( 2 mol) was added and stirred at 60 ° C. for 3 hours, and then 15 mol% of diphenyl (1-cyclopentadienyl) (2,7-di-tert.) With respect to bis (cyclopentadienyl) zirconium dichloride. -Butyl-9-fluorenyl) zirconium dichloride 2.36 g (3.53 mmol) was added and stirred at room temperature for 6 hours. The supernatant was removed by standing, and a hexane solution (0.15M) of triisobutylaluminum was further added to finally obtain a catalyst slurry of 100 g / L.

[Preparation of polymerization catalyst (q)]
500 g of the modified hectorite was suspended in 1.7 liters of hexane, and 6.63 g (20.0 mmol) of propane-1,3-diylbis (cyclopentadienyl) zirconium dichloride and a hexane solution of triisobutylaluminum (0.714 M ) After adding 2.8 liters (2 mol) of the mixed solution and stirring at 60 ° C. for 3 hours, 5 mol% of diphenylmethylene (1−5 mol) with respect to propane-1,3-diylbis (cyclopentadienyl) zirconium dichloride. 0.58 g (1.05 mmol) of cyclopentadienyl) (9-fluorenyl) zirconium dichloride was added and stirred at room temperature for 6 hours. The supernatant was removed by standing, and a hexane solution (0.15M) of triisobutylaluminum was further added to finally obtain a catalyst slurry of 100 g / L.

[Production of ethylene polymer]
Into a polymerization vessel having an internal volume of 540 liters, 300 liters of hexane and 6.1 liters of 1-butene were introduced, and the internal temperature of the autoclave was raised to 80 ° C. Polymerization was started by adding 250 ml of the polymerization catalyst (q) to this autoclave and introducing an ethylene / hydrogen mixed gas (hydrogen: containing 2000 ppm) until the partial pressure reached 0.9 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 0.9 MPa. The polymerization temperature was controlled at 80 ° C. After 90 minutes from the start of polymerization, the internal pressure of the polymerization vessel was released, and the contents were filtered and dried to obtain 53 kg of an ethylene polymer powder. The ethylene polymer powder was melt kneaded and pelletized using a 50 mm diameter single screw extruder set at 200 ° C. to obtain ethylene copolymer pellets. The density of the obtained ethylene polymer pellets was 930 kg / m ³ , and the MFR was 4 g / 10 min.

Synthesis example 2
[Production of ethylene polymer]
Into a polymerization vessel having an internal volume of 540 liters, 300 liters of hexane and 6.1 liters of 1-butene were introduced, and the internal temperature of the autoclave was raised to 80 ° C. Polymerization was started by adding 250 ml of the polymerization catalyst (q) to this autoclave and introducing an ethylene / hydrogen mixed gas (hydrogen: containing 2000 ppm) until the partial pressure reached 0.9 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 0.9 MPa. The polymerization temperature was controlled at 80 ° C. After 90 minutes from the start of polymerization, the internal pressure of the polymerization vessel was released, and the contents were filtered and dried to obtain 53 kg of an ethylene polymer powder. The ethylene polymer powder was melt kneaded and pelletized using a 50 mm diameter single screw extruder set at 200 ° C. to obtain ethylene copolymer pellets. The density of the obtained ethylene polymer pellets was 930 kg / m ³ , and the MFR was 3 g / 10 min.

Example 1
The ethylene polymer pellets obtained in Synthesis Example 1 were supplied to an air-cooled inflation molding machine (model LL-50, manufactured by Plako Co., Ltd.) having a circular die with a diameter of 75 mmφ. Extruder cylinder temperature: 180 ° C., extrusion Resin temperature: 180 ° C., lip clearance 2.0 mm, blow ratio 2.0, take-up speed 16 m / min. Moreover, haze and blocking resistance were evaluated using this film. The results are shown in Table 1.

Example 2
A film was prepared in the same manner as in Example 1 except that the take-up speed was 24 m / min and the thickness was 20 μm, and the film-forming stability, haze, and blocking properties were evaluated. The results are shown in Table 1.

Example 3
A film was prepared in the same manner as in Example 1 except that the take-up speed was 8 m / min and the thickness was 80 μm, and the film-forming stability, haze, and blocking properties were evaluated. The results are shown in Table 1.

Example 4
A film was prepared in the same manner as in Example 1 except that the lip clearance was 2.0 mm, and film forming stability, haze, and blocking properties were evaluated. The results are shown in Table 1.

Example 5
A film was prepared in the same manner as in Example 1 except that the ethylene polymer obtained in Synthesis Example 2 was used, and the film-forming stability, haze, and blocking properties were evaluated. The results are shown in Table 1.

Comparative Example 1
Example 1 except that a commercially available linear low-density polyethylene (Nipolon-L F15R, manufactured by Tosoh Corporation, MFR = 0.8 g / 10 min, density = 925 kg / m ³ ) was used as the ethylene polymer. Films were prepared in the same manner as described above, and film formation stability, haze, and blocking properties were evaluated. Although a result is described in Table 2, it was inferior to film forming stability and blocking resistance.

Comparative Example 2
In the same manner as in Example 1 except that a commercially available low density polyethylene (Petrocene 180R, manufactured by Tosoh Corporation, MFR = 2.0 g / 10 min, density = 922 kg / m ³ ) was used as the ethylene polymer. Films were prepared and evaluated for film formation stability, haze, and blocking properties. Although a result is described in Table 2, it was inferior to blocking resistance.

Comparative Example 3
The film was prepared in the same manner as in Example 1 except that a commercially available linear low density polyethylene (Umerit 4540F, manufactured by Ube Industries, MFR = 3.9 g / 10 min, density = 944 kg / m ³ ) was used. The film formation stability, haze, and blocking property were evaluated. The results are shown in Table 2, but the film formation stability was inferior, and a film could not be obtained stably.

Comparative Example 4
A film was prepared in the same manner as in Example 1 except that a commercially available metallocene polyethylene (Harmorex NH745S, manufactured by Nippon Polyethylene Co., Ltd., MFR = 9.0 g / 10 min, density = 912 kg / m3) was used. The film stability, haze, and blocking properties were evaluated. The results are shown in Table 2, but the film formation stability was inferior, and a film could not be obtained stably.

  The film of this invention is excellent in blocking resistance, without adding an antiblocking agent. Therefore, it can be used as a package for foods, pharmaceuticals and industrial chemicals as a film having blocking resistance and excellent cleanliness.

Claims (3)

It consists of a repeating unit derived from ethylene, or an ethylene polymer consisting of a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms and satisfying the following requirements (A) to (H). The film satisfying the following requirements (I) to (J).
(A) Density measured by JIS K6922-1 (1998) is 910 kg / m ³ or more and 940 kg / m ³ or less (B) Melt mass flow rate (MFR) measured by JIS K6922-1 (1998) is 0 0.1-20 g / 10 min (C) 0.2 or less terminal vinyl per 1,000 carbon atoms (D) Melt tension at 160 ° C. [MS ₁₆₀ (mN)] measured by a capillary viscometer of 40 or more 150 or less (E) The melt tension MS _{160 at} 160 ° C. measured by a capillary viscometer and the melt tension [MS ₁₉₀ (mN)] at 190 ° C. satisfy the following formula (1) MS ₁₆₀ / MS ₁₉₀ <1.8 (1 )
(F) Flow activation energy [Ea (kJ / mol)] is 30 or more and less than 50 (G) Multiple peaks are present in the elution temperature-elution amount curve obtained by temperature rising elution fractionation (H) Gel permeation The ratio of the z-average molecular weight to the weight-average molecular weight (Mz / Mw) and the ratio of the weight-average molecular weight to the number-average molecular weight (Mz / Mw) / (Mw / Mn), which were determined by the measurement of the chromatography (GPC) less than 0.9 (I) JIS K7105 haze was measured according to (1981) [Hz (%)] is more than 20% (J) silica, talc, zeolite, mica, carbon, calcium carbonate, magnesium carbonate Not included The method for producing a film according to claim 1, wherein the film is produced under conditions satisfying the following requirements (K) to (M).
(K) Created by air-cooled inflation molding method (L) Film thickness is 10 μm or more and 300 μm or less (M) Shear rate when molten resin is extruded from die is 30 s ⁻¹ or more and 1,500 s ⁻¹ or less A multilayer film comprising the film according to claim 1 as an outermost layer.