JP6314510B2 - Method for producing packaging film - Google Patents

Description

  The present invention relates to a method for producing a packaging film. Specifically, when used as an intermediate layer for packaging materials for liquids and mucilages in automatic filling machines such as die rolls, it has excellent bag breaking strength and low-temperature sealing properties, and high-speed liquids in a wide temperature range from low to high temperatures. The present invention relates to a method for producing a packaging film that can be filled.

  Conventionally, packaging of liquids and mucilages, and liquids and mucilages containing solids such as fibers and powders as insoluble substances, various intermediate layers are laminated on the substrate as necessary, A laminated film obtained by laminating a sealant layer thereon is used. As such a laminated film, a packaging film is known in which a sealant layer is provided on a surface base material layer made of polyamide resin, polyethylene terephthalate resin, paper, aluminum foil, etc., and the heat sealability of this sealant layer is utilized. ing.

As a resin used for this sealant layer, for example, a random copolymer of ethylene / C _4-10 α-olefin having specific physical properties and high-pressure low-density polyethylene (hereinafter sometimes abbreviated as HPLD) may be used. A blend composition has been proposed (see Patent Document 1). Specifically, an ethylene-4-methyl-1-pentene random copolymer produced with an Mg-Ti catalyst has been proposed as the random copolymer, but the disadvantage is that the foaming start temperature of the lateral seal portion is low. There is.

Further, a blend composition of an ethylene / C _3-18 α-olefin copolymer and HPLD exhibiting specific temperature rising elution fractionation (hereinafter sometimes abbreviated as TREF) characteristics has been proposed (Patent Document 2). reference). Specifically, linear low-density polyethylene (such as an ethylene / 1-hexene copolymer) produced with a metallocene catalyst has been proposed as the above-mentioned copolymer. Because it is sealed as a contaminant, the pressure and heat received from the heat sealer will cause a resin pool based on the peeling of the base material and the intermediate layer at the seal part (the sealant layer and the intermediate layer are raised in a bump shape) If a seal failure occurs due to generation, while the pressure and temperature of the sealer are lowered, a seal failure occurs due to insufficient low-temperature heat sealability and hot tackiness of the sealant layer, resulting in reduced seal strength, reduced pressure strength, and foreign matter inclusion Liquid leakage or the like is likely to occur, and as a result, the filling speed could not be increased.

In addition, a blend composition of a random copolymer of ethylene / C _4-10 α-olefin having specific physical properties and HPLD has been proposed (see Patent Document 3). Specific examples of the random copolymer include linear low density polyethylene (ethylene / 1-hexene copolymer, ethylene / 1-butene copolymer, ethylene / 1-octene copolymer, etc.) produced with a metallocene catalyst. However, as in the case of the above-mentioned Patent Document 2, there is a defect that a seal failure is likely to occur due to low temperature heat sealability and insufficient hot tack.

  In view of such a problem, a coextruded multilayer film for bonding in which a specific three-layer structure film composed of an inner layer, an intermediate layer, and an outer layer is coextruded on a base material layer has been proposed (see Patent Document 4). However, this laminated film has an advantage of excellent impact resistance, but has a problem that it cannot be filled with a liquid filling machine. Patent Document 4 discloses a prescription in which a linear low density polyethylene produced using a Ziegler-based catalyst is blended in the inner layer, and a considerable amount of highly crystalline components are present in the linear low density polyethylene. This is considered to be the cause of the problem.

  In addition, a three-layer structure film has been proposed in which an intermediate layer having specific physical properties composed of a blend of linear low density polyethylene and HPLD is provided on the base material layer, and a normal sealant layer is provided on the outer layer (see Patent Document 5). ). However, the laminated film produced by this method is a bag-made product and has an advantage of having a high bag breaking strength, but has a problem that it is inferior in filling suitability in a liquid filling and packaging machine.

Further, a packaging laminate having a three-layer structure in which a random copolymer of ethylene / C _3-10 α-olefin having specific thermal properties is used as an intermediate layer and a sealant layer and the thickness is specified has been proposed ( (See Patent Document 6). As the sealant layer, it is described that HPLD may be added to the random copolymer in an amount of 0 to 70% by weight, but no specific example is shown. This laminated film has the advantage that high-speed liquid filling suitability under certain conditions can be obtained, but there is a problem that high-speed liquid filling suitability cannot be obtained at a wide range of sealing temperatures.

  Therefore, it is necessary to adjust the setting conditions of the filling device in order to cope with various contents, differences in the base material, etc., but in the conventional one, the allowable range in each packaging material is narrow, and the filling conditions are changed each time. Problems such as the need to search are not solved.

Japanese Patent Publication No.2-4425 JP 7-26079 A JP-A-8-269270 JP-A-10-323948 Japanese Patent Laid-Open No. 11-10809 JP-A-11-254614

  In view of the above-mentioned problems, the object of the present invention is to have an intermediate layer made of a polyethylene resin composition that is excellent in bag breaking strength and low-temperature sealability and that allows high-speed liquid filling in a wide temperature range from low temperature to high temperature. An object of the present invention is to provide a simple method for producing a liquid or viscous packaging film.

  As a result of intensive studies to solve the above problems, the present inventors have found that a resin composition comprising an ethylene / α-olefin copolymer having a specific composition and physical properties and high-pressure low-density polyethylene is liquid by extrusion laminating or the like. The present inventors have found that the above problems can be solved when used as a sealing layer for a viscous packaging material.

That is, according to the first invention of the present invention, at least the base material layer, the intermediate layer and the sealant layer are laminated in this order, and the method for producing a packaging film used in a die roll type automatic filling machine, A layer is comprised from the polyethylene resin composition (C) which consists of a copolymer (A) of ethylene and C3-C20 alpha olefin, and a high-pressure method low density polyethylene (B), and the following (1)-( Provided is a method for producing a packaging film, which is prepared so as to satisfy the condition 3).
(1) The storage elastic modulus (E ′ ₁₀₀ ) measured at 100 ° C. is 12.0 to 13.5 MPa.
(2) The storage elastic modulus (E ′ ₁₁₀ ) measured at 110 ° C. is 1.5 to 4.0 MPa.
(3) E ′ ₁₀₀ (unit MPa) and E ′ ₁₁₀ (unit MPa) have the following relationship.
9.5 ≦ E ′ ₁₀₀ −E ′ ₁₁₀ ≦ 11.0

  According to the second invention of the present invention, in the first invention, the polyethylene resin composition constituting the intermediate layer has a melt flow ratio (MFR) of 0.1 to 100 g / 10 min. A method for producing a packaging film is provided.

  According to the third invention of the present invention, in the first or second invention, the MFR of the ethylene / α-olefin copolymer (A) is smaller than the MFR of the high-pressure low-density polyethylene (B). A method for producing a packaging film is provided.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the ethylene / α-olefin copolymer (A) is obtained using a metallocene catalyst. A method of manufacturing a film is provided.

  According to a fifth aspect of the present invention, there is provided a method for producing a packaging film according to any one of the first to fourth aspects, wherein the filling and packing form of the automatic filling machine is a three-way seal. Is done.

  By the method for producing a packaging film of the present invention, it is possible to more easily produce a packaging film that has excellent bag breaking strength and low-temperature sealing properties, and that enables high-speed liquid filling in a wide temperature range from low temperature to high temperature. it can.

The present invention is a method for producing a packaging film in which at least a base material layer, an intermediate layer, and a sealant layer are laminated in this order by an extrusion laminating method, and the intermediate layer comprises ethylene and an α having 3 to 20 carbon atoms. -Storage elastic modulus (E ') measured at 100 ° C and 110 ° C, which is composed of a copolymer (A) with an olefin and a polyethylene resin composition (C) consisting of a high-pressure method low-density polyethylene (B) It is prepared so as to satisfy the following conditions.
Hereinafter, each component which comprises each layer, the manufacturing method of the film for packaging, etc. are demonstrated for every item.

1. Intermediate layer (1) Ethylene / α-olefin copolymer (A)
The ethylene / α-olefin copolymer (A) used in the present invention is a main component of the polyethylene resin composition (C) constituting the intermediate layer in the present invention.
The ethylene / α-olefin copolymer (A) is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. The α-olefin used as a comonomer is a 1-olefin having 3 to 20 carbon atoms, preferably 4 to 12 carbon atoms, more preferably 4 to 8 carbon atoms. Specifically, propylene, 1-butene, 1 -Pentene, 1-hexene, 1-octene, 1-heptene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene and the like can be mentioned. Specific examples of the ethylene / α-olefin copolymer (A) include an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, and an ethylene / 1-octene copolymer.

  The α-olefin used as a comonomer is not limited to one type, and a multi-component copolymer using two or more types like a terpolymer is also preferable. Specific examples include an ethylene / propylene / 1-butene terpolymer and an ethylene / propylene / 1-hexene terpolymer.

  The ethylene / α-olefin copolymer (A) is preferably composed mainly of structural units derived from ethylene, and the ethylene content is 50 to 99% by weight, more preferably 60 to 97% by weight, and still more preferably. Is selected from the range of 70 to 95% by weight. Therefore, the α-olefin content is preferably selected from the range of 1 to 50% by weight, more preferably 3 to 40% by weight, and still more preferably 5 to 30% by weight.

The melt flow rate (MFR) of the ethylene / α-olefin copolymer (A) is preferably 1 to 50 g / 10 minutes, more preferably 3 to 20 g / 10 minutes. When the MFR is in the above range, the heat resistance at the time of sealing can be improved (technical significance). In addition, MFR is the value measured based on JIS-K6922-2: 1997 appendix (190 degreeC, 21.18N load).
In addition, as will be described later, from the viewpoint of suppressing a decrease in storage elastic modulus at the time of sealing the high pressure method low density polyethylene, the MFR of the ethylene / α-olefin copolymer (A) is the MFR of the high pressure method low density polyethylene (B). Is preferably smaller.

The density of the ethylene · alpha-olefin copolymer (A) is preferably 0.870~0.940g / cm ^3, more preferably 0.900~0.915g / cm ^3. When the density is in the above range, the sealing temperature can be lowered. In addition, a density is the value measured based on JIS-K6922-2: 1997 appendix (23 degreeC).

(Method for producing ethylene / α-olefin copolymer)
The ethylene / α-olefin copolymer used in the present invention can be easily produced by polymerization using a metallocene catalyst. The metallocene catalyst is (i) a transition metal compound of Group 4 of the periodic table (so-called metallocene compound) containing a ligand having a cyclopentadienyl skeleton, and (ii) a stable ionic state by reacting with the metallocene compound. A catalyst comprising an activatable cocatalyst and, if necessary, (iii) an organoaluminum compound, any known catalyst can be used. Hereinafter, the components (i) to (iii) will be described.

  (I) Metallocene compounds include, for example, JP-A-58-19309, JP-A-59-95292, JP-A-59-23011, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, JP-A-60-35209, JP-A-61-130314, JP-A-3-163888, etc., EP publication 420,436, US Pat. No. 5,055,438, international publication WO91 / 04257, International Publication WO92 / 07123, and the like.

  More specifically, bis (cyclopentadienyl) zirconium dichloride, bis (indenyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, bis (azurenyl) zirconium dichloride, bis (4,5,6,7-tetrahydroindenyl) ) Zirconium dichloride, (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) zirconium dichloride, methylenebis (cyclopentadienyl) zirconium dichloride, methylene (cyclopentadienyl) (3,4-dimethylcyclopentadi) Enyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) zirconium dichloride, ethylene (cyclopentadienyl) (3,5-dimethylpe Tadienyl) zirconium dichloride, methylenebis (indenyl) zirconium dichloride, ethylenebis (2-methylindenyl) zirconium dichloride, ethylene 1,2-bis (4-phenylindenyl) zirconium dichloride, ethylene (cyclopentadienyl) (fluorenyl) Zirconium dichloride, dimethylsilylene (cyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (indenyl) zirconium dichloride, dimethylsilylene bis (4,5,6,7-tetrahydroindenyl) zirconium dichloride, Dimethylsilylene (cyclopentadienyl) (fluorenyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (octahydride) Fluorenyl) zirconium dichloride, methylphenylsilylene bis [1- (2-methyl-4,5-benzo (indenyl)] zirconium dichloride, dimethylsilylene bis [1- (2-methyl-4,5-benzoindenyl)] zirconium Dichloride, dimethylsilylenebis [1- (2-methyl-4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylene Bis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] zirconium dichloride, diphenylsilylene Screw [1- ( 2-methyl-4- (4-chlorophenyl) -4H-azulenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4- (phenylindenyl))] zirconium dichloride, dimethylsilylenebis [1- ( 2-ethyl-4- (phenylindenyl))] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azulenyl)] zirconium dichloride, dimethylgermylenebis (indenyl) zirconium dichloride, dimethyl Zirconium compounds such as germylene (cyclopentadienyl) (fluorenyl) zirconium dichloride can be exemplified. In the above, a compound in which zirconium is replaced with hafnium can be used similarly. In some cases, a mixture of a zirconium compound and a hafnium compound can be used.

The metallocene compound may be used by being supported on an inorganic or organic compound carrier. The support is preferably a porous oxide of an inorganic or organic compound, specifically, an ion-exchange layered silicate, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , B ₂ O ₃ , CaO. ZnO, BaO, ThO _{2 and the} like, or a mixture thereof.

  (Ii) Examples of the cocatalyst used in the present invention include organoaluminum oxy compounds (aluminoxane compounds), ion-exchange layered silicates, Lewis acids, boron compounds, lanthanoid salts such as lanthanum oxide, tin oxide, and the like.

  (Iii) Examples of organoaluminum compounds include trialkylaluminums such as triethylaluminum, triisopropylaluminum, triisobutylaluminum; dialkylaluminum halides; alkylaluminum sesquihalides; alkylaluminum dihalides; alkylaluminum hydrides, organoaluminum alkoxides, etc. Can be mentioned.

As the polymerization method, any method can be adopted as long as the catalyst component and each monomer come into efficient contact. Specific examples include a slurry method, a gas phase fluidized bed method and a solution method in the presence of these catalysts, or a high-pressure bulk polymerization method in which a pressure is 200 kg / cm ² or more and a polymerization temperature is 100 ° C. or more. . A preferable production method includes high-pressure bulk polymerization.

  Such an ethylene copolymer can be appropriately selected from those commercially available as metallocene polyethylene and used. Examples of commercially available products include “Affinity” manufactured by DuPont Dow, “Kernel” and “Harmolex” manufactured by Nippon Polyethylene. An ethylene-type copolymer can be used 1 type or in mixture of 2 or more types. Two or more ethylene / α-olefin copolymers having different densities or MFRs may be used in combination. Since the ethylene copolymer based on metallocene catalyst has a narrow crystallinity distribution, high-speed liquid filling is possible in a wide range by blending various copolymers.

  The ethylene / α-olefin copolymer is preferably produced using a metallocene catalyst, but can also be produced using a so-called Ziegler catalyst containing titanium and halogen.

2. High pressure low density polyethylene (B)
Another component constituting the polyethylene resin composition (C) used in the intermediate layer of the present invention is high-pressure low-density polyethylene (hereinafter also referred to as “HPLD”) (B). Also referred to as polymerized low density polyethylene. High-pressure low-density polyethylene has high melt elasticity, and is often used to improve neck-in particularly during extrusion lamination.

  The physical properties of the high pressure method low density polyethylene (B) in the present invention are not particularly specified, and conventionally known high pressure method low density polyethylene can be used. The high-pressure low-density polyethylene (B) used is not limited to one type, and two or more types may be used.

The high pressure method low density polyethylene (B) preferably has an MFR of 3 to 80 g / 10 min, particularly preferably 10 to 30 g / 10 min. When the MFR is in the above range, the resin pressure and the motor load at the time of laminate molding can be reduced. Further, the high-pressure low-density polyethylene (B) has a density of preferably 0.910 to 0.930 g / cm ³ , particularly preferably 0.915 to 0.925 g / cm ³ . When the density is in the above range, low-temperature sealing is not inhibited when blended with a high-pressure low-density polyethylene and an ethylene / α-olefin copolymer.

3. Polyethylene resin composition (C)
In the present invention, the intermediate layer of the packaging film is composed of a polyethylene resin composition (C) composed of an ethylene / α-olefin copolymer (A) and a high-pressure low-density polyethylene (B), and 100 ° C. and The storage elastic modulus at 110 ° C. is prepared so as to satisfy a specific condition.

(1) Blending ratio The blending ratio of each component of the polyethylene resin composition (C) is not particularly limited and can be appropriately adjusted so as to satisfy a specific storage elastic modulus described later. Usually, ethylene / α- The total amount of the olefin copolymer (A) and the high pressure method low density polyethylene (B) is 100% by weight, and the ethylene / α-olefin copolymer (A) is 40 to 90% by weight, the high pressure method low density polyethylene (B). 10 to 60% by weight, preferably 45 to 80% by weight of the ethylene / α-olefin copolymer (A), and 20 to 55% by weight of the high-pressure low-density polyethylene (B), more preferably ethylene / α. -The olefin copolymer (A) is 50 to 70% by weight, and the high-pressure low-density polyethylene (B) is 30 to 50% by weight. When the blending ratio is in the above range, the storage elastic modulus suitable for the filling conditions can be adjusted, and a packaging material excellent in bag breaking strength and low-temperature sealability can be laminated.

When two types of metallocene polyethylene copolymers having different densities are used in combination as the ethylene / α-olefin copolymer (A), for example, a copolymer having a density of 0.88 to 0.91 g / cm ³ is used. 35-70% by weight, the copolymer having a density 0.91~0.94g / cm ³ and 5-35 wt%, to which the high-pressure low-density polyethylene having a density of 0.90~0.93g / cm ³ 5 The aspect which mix | blends -40weight% is preferable.

  Moreover, you may mix | blend another compounding agent suitably other than the said component. For example, 0-5 parts by weight of a compounding agent such as a slip agent can be blended with 100 parts by weight of the polyethylene resin composition (C). Other compounding agents include antioxidants, light stabilizers, UV absorbers, antistatic agents, antifogging agents, crystal nucleating agents, neutralizing agents, metal deactivators, colorants, dispersants, peroxides. , Fillers, fluorescent brighteners and the like.

(2) Physical properties of polyethylene resin composition (C) In the polyethylene resin composition (C) used as the intermediate layer, the present invention is prepared so that the following characteristics (A) to (C) are in a specific range. Thus, a simpler method for producing a packaging film having a bag breaking strength, workability, and low-temperature sealability is provided for each component used without searching for the filling conditions each time. Hereinafter, each characteristic will be described sequentially.

(A) Viscoelasticity The present invention is characterized in that the polyethylene resin composition (C) is prepared to have the following storage elastic modulus (1) to (3) derived from viscoelasticity measurement.
(1) The storage elastic modulus (E ′ ₁₀₀ ) measured at 100 ° C. is 12.0 to 13.5 MPa.
(2) The storage elastic modulus (E ′ ₁₁₀ ) measured at 110 ° C. is 1.5 to 4.0 MPa.
(3) E ′ ₁₀₀ (unit MPa) and E ′ ₁₁₀ (unit MPa) have the following relationship.
9.5 ≦ E ′ ₁₀₀ −E ′ ₁₁₀ ≦ 11.0

The storage elastic modulus is a component having the same phase as that of a strain causing a phase difference δ with respect to a strain applied when measuring a stress when a sine wave having a predetermined frequency is applied to a sample. The storage elastic modulus E ′ corresponds to the elastic response of the sample when it is separated into components that are out of phase with each other, and the elastic modulus is obtained from the maximum value. These definitions are described in, for example, “Lectures / Rheology”, edited by Japanese Society of Rheology, Kobunshi Shuppankai 1992, pp. 36-37.
In the method of the present invention, the polyethylene resin composition (C) used for the intermediate layer is adjusted to the storage viscosities specified in the above (1) to (3), thereby allowing various contents, differences in base materials, and the like. A packaging film that is easily superior in bag breaking strength and low-temperature sealability and capable of high-speed liquid filling in a wide temperature range from low temperature to high temperature is prepared without adjusting the setting conditions to cope with .

The storage elastic modulus (E ′ ₁₀₀ ) measured at 100 ° C. of the polyethylene resin composition (C) is 12.0 to 13.5 MPa, preferably 12.1 to 13.3 MPa, particularly preferably 12.2. ˜13.0 MPa.
When the storage elastic modulus at 100 ° C. is higher than the above range, the deformation of the material is suppressed, so the low temperature heat sealability is poor. On the other hand, when the storage elastic modulus is lower than the above range, the deformation of the material becomes excessive and the heat resistance is poor.
Further, E ′ ₁₀₀ can be controlled within the above range by preparing a large amount of high-pressure method low-density polyethylene at a blending ratio of ethylene / α-olefin and high-pressure method low-density polyethylene.

The storage elastic modulus (E ′ ₁₁₀ ) measured at 110 ° C. is 1.5 to 4.0 MPa, preferably 2.0 to 3.5 MPa.
When the storage elastic modulus at 110 ° C. is higher than the above range, the deformation of the material is suppressed, so that the low-temperature sealing property is poor. On the other hand, when the storage elastic modulus is lower than the above range, the deformation of the material becomes excessive, so the heat resistance is poor.
Further, E ′ ₁₁₀ is prepared by increasing the ratio of ethylene / α-olefin by the blending ratio of ethylene / α-olefin and high-pressure process low-density polyethylene (/ by the same preparation method as E ′ ₁₀₀ above). The range can be controlled.

Further, when E ′ ₁₀₀ and E ′ _{110 of} the polyethylene resin composition (C) satisfy the above range, and E ′ ₁₀₀ (unit MPa) and E ′ ₁₁₀ (unit MPa) are in the following relationship, it is good. Low temperature sealability and heat resistance can be obtained.
9.5 ≦ E ′ ₁₀₀ −E ′ ₁₁₀ ≦ 11.0
When the storage elastic modulus of E ′ ₁₀₀ -E ′ ₁₁₀ is higher than the above range, the deformation of the material is suppressed, so that the low temperature sealing property is inferior. On the other hand, when the storage elastic modulus is lower than the above range, the deformation of the material becomes excessive. Inferior to sex.
E ′ ₁₀₀ -E ′ ₁₁₀ is controlled within the above range by adjusting the blending ratio of ethylene / α-olefin and high-pressure method low density polyethylene (/ by the same preparation method as E ′ ₁₀₀ above). Can do.

The storage elastic modulus can be obtained by measuring under the following conditions.
[conditions]
Apparatus: E4000F manufactured by UBM Co., Ltd.
Measurement mode: Temperature dependence Frequency: 1Hz
Distortion: Setting 0.2% (automatic adjustment)
Auto tension: Automatic static load (minimum load 25g)
Temperature increase rate: 5 ° C / min
Sample shape: A film formed or a film press-molded to a thickness of about 0.3 mm to 0.5 mm is cut into a strip shape having a width of 5 mm and a length of 25 mm, and mounted on the apparatus.
[Measuring method]
The storage elastic modulus of the sample is measured in the temperature range of 30 ° C to 140 ° C.

(B) Density characteristics The density of the polyethylene resin composition (C) is preferably 0.90 to 0.94 g / cm ³ , particularly preferably 0.91 to 0.92 g / cm ³ . If the density is higher than the above range, the low temperature heat sealability is poor. If the density is lower than the above range, it is not preferable because it tends to foam when sealed at a high temperature. In addition, a density is the value measured based on JIS-K6922-2: 1997 appendix (23 degreeC).

(C) Melt Flow Rate (MFR) Properties The MFR (190 ° C., 21.18 N load) of the polyethylene resin composition (C) is preferably 1 to 100 g / 10 minutes, more preferably 2 to 50 g / 10 minutes, particularly Preferably it is 4-20 g / 10min. If the MFR is lower than the above range, the extrusion load when the resin is melt-extruded becomes high, and the film surface becomes rough during molding, which is not preferable. If the MFR exceeds the above range, the hot tack property at the time of heat sealing is lowered, or the bag breaking strength when used as a packaging material is lowered, which is not preferable. In addition, MFR is the value measured based on JIS-K6922-2: 1997 appendix (190 degreeC, 21.18N load).
The MFR of the ethylene / α-olefin copolymer (A), which is a constituent of the polyethylene resin composition (C), is preferably smaller than the MFR of the high-pressure method low-density polyethylene (B). The reason for this will be described below.
When the MFR of the high pressure method low density polyethylene (B) is small, the change in storage elastic modulus derived from the high pressure method low density polyethylene at the transverse seal temperature (130 to 165 ° C.) becomes small. As a result, deformation of the material due to temperature change is suppressed, resulting in poor low-temperature sealability.

4). BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a method for producing a packaging film used in a die roll type automatic filling machine in which at least a base material layer, an intermediate layer and a sealant layer are laminated in this order by an extrusion laminating method.
This invention can be set as the film for packaging by laminating | stacking on a base material by using as an intermediate | middle layer the polyethylene resin composition (C) prepared by the said method. Specifically, it is a packaging material in which a layer made of the resin composition of the present invention is laminated as a heat seal layer on one side of a substrate.
As the base material layer constituting the laminate, paper, aluminum foil, cellophane, woven fabric, non-woven fabric, polymer film, for example, high density polyethylene, medium density polyethylene, low density polyethylene, ethylene / vinyl acetate copolymer Polymers, ethylene / acrylic acid ester copolymers, ionomers, polypropylene, poly-1-butene, poly-4-methylpentene-1, and other olefin polymers, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyacrylate, polyacrylonitrile Vinyl copolymers such as nylon 6, nylon 66, nylon 7, nylon 10, nylon 11, nylon 12, nylon 610, polyamides such as polymetaxylylene adipamide, polyethylene terephthalate, polyethylene terephthalate / isophthalate, polybutylene Polyester terephthalate, such as, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, may be mentioned a film of polycarbonate. Further, one kind of the above film may be used alone, or two or more kinds of the above films may be used in combination. Further, depending on the kind of the base material, the film may be stretched. In particular, a uniaxial or biaxially stretched polypropylene film, a stretched nylon film, a stretched polyethylene terephthalate film, a stretched polystyrene film, or the like is also used. Further, a substrate obtained by coating polyvinylidene chloride, polyvinyl alcohol or the like on the above substrate, or a substrate obtained by vapor deposition of aluminum, alumina, silica, or a mixture of alumina and silica may be used. As a liquid or viscous packaging material, a biaxially stretched nylon film, a biaxially stretched polyethylene terephthalate film, or a material obtained by vapor-depositing silica or alumina on a base material is often used.

  The method for providing the heat seal layer on the surface of the substrate is not particularly limited and can be carried out according to a known method. For example, there are a dry lamination method, a wet lamination method, an extrusion method, a sandwich lamination method, a coextrusion method, and the like. A film for a heat seal layer used for dry lamination or the like can be produced by any method such as a calendar method, an air-cooled inflation method, a water-cooled inflation method, or a T-die molding method using the ethylene resin and the propylene resin.

  In the case of an extrusion method, an extrusion laminating method, a dry laminating method, a sandwich laminating method, a coextrusion method (coextrusion without an adhesive layer, coextrusion with an adhesive layer, coextrusion with an adhesive resin, etc. Method). A tandem extrusion laminating method is often used as a method for producing a liquid or viscous packaging material with a laminated film comprising the resin composition of the present invention. This is a method of sequentially laminating two types of resin layers, such as an intermediate layer as the first layer and a sealant layer as the second layer on the base material by extrusion laminating method. Is preferred.

  The thickness of the entire laminated film, the thickness of each layer, and the thickness ratio are not particularly limited and may be appropriately determined according to the contents, usage, and the like. Specifically, the thickness of the entire laminated film is 40 to 120 μm. The thickness of the material layer is preferably about 10 to 40 μm, and the thickness of the sealant layer is preferably about 10 to 40 μm. When providing an intermediate layer, the thickness of the intermediate layer is preferably about 20 to 40 μm. Further, in the case of lamination, surface treatment such as corona discharge treatment, ozone treatment, flame treatment or the like can be performed on the substrate in advance in order to improve the adhesion of the substrate surface. Furthermore, it is preferable to apply an anchor coating agent on the base material in advance for the purpose of enhancing adhesion and the like. Examples of the anchor coating agent include isocyanate-based, polyethyleneimine-based, and polybutadiene-based agents.

  The packaging film produced according to the present invention thus obtained can be used as various packaging materials such as food packaging materials, medical packaging materials, and industrial material packaging materials such as engine oil. In particular, the packaging film produced according to the present invention has excellent bag breaking strength, processability, low-temperature sealing properties, etc., and therefore fluids such as liquids, mucilages, and the like containing solid insoluble materials such as liquids, fibers, and powders. Is preferably used as a packaging material for storing the contents as a content, and is preferably used when a die roll type automatic filling machine, in particular, a filling and packaging form is a three-way seal.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
The measurement methods, evaluation methods, and materials used in the examples and comparative examples are as follows.

1. Measurement method and evaluation method (1) Density: Performed according to JIS-K6922-2: 1997 appendix (23 ° C.).
(2) Performed according to MFR: JIS-K6922-2: 1997 appendix (190 ° C., 21.18 N load).
(3) Storage elastic modulus E ′: Solid viscoelasticity was measured under the following conditions.
Apparatus: E4000F manufactured by UBM Co., Ltd.
Measurement mode: Temperature dependence Frequency: 1Hz
Distortion: Setting 0.2% (automatic adjustment)
Auto tension: Automatic static load (minimum load 25g)
Temperature increase rate: 5 ° C / min
Sample shape: A film formed or a film press-molded to a thickness of about 0.3 mm to 0.5 mm is cut into a strip shape having a width of 5 mm and a length of 25 mm and attached to the apparatus.
Measurements were made from −50 ° C. to 150 ° C. at a rate of temperature increase of 5 ° C./min, and the storage elastic modulus (E ′) at temperatures 100 and 110 ° C. was determined from the obtained data.

[Filling conditions]
Sealing temperature: (vertical) 185 ° C, (horizontal) in the range of 130-165 ° C in increments of 5 ° C
Packaging form: Three-sided seal Bag size: 50mm width x 100mm pitch Filling: 30 ° C water Filling amount: about 10cc
Filling speed: 20 m / min
The seal temperature range was examined by evaluating the following 1) and 2) for the horizontal seal portion of the obtained liquid-filled sachet. A case where there was no problem in each case was marked with ◯, and a case where there was a problem was marked with ×.

1) Evaluation of bag breaking strength Using a Tensilon universal material testing machine (Orientec Co., Ltd., RTC-1210A), a load was applied to the bag after filling at 1 mm / min to evaluate the load when the bag was broken. Those that could withstand a load of 200 kg or more were marked with ◯, and those that could not withstand were marked with ×.

2) Appearance observation evaluation of seal part If the horizontal seal temperature is high, bag breakage and water leakage will not occur. However, if the transverse seal temperature becomes too high, the transverse seal portion begins to foam, making it unsuitable as a packaging film. Therefore, the horizontal seal portion of the liquid sachet was observed. The case where heat resistance was inferior and foaming occurred or a bag breakage or water leakage occurred was evaluated as x.

2. Material (1) Ethylene / α-olefin copolymer (A)
A1 used as the ethylene / α-olefin copolymer is produced by a gas phase method using a metallocene catalyst. In addition, 1-hexene is used for the comonomer. The properties are as shown in Table 1.

(2) High pressure low density polyethylene (HPLD)
B1 and B2 used as the high pressure method low density polyethylene were produced in a high pressure radical method low density polyethylene production facility having an autoclave reactor. The properties are as shown in Table 1.

  Table 1 shows the blending ratio of each resin component of the polyethylene resin composition (C) used in the intermediate layer of the present invention.

3. Example and Comparative Example (1) Production of packaging film by extrusion lamination process Using a 90 mmφ single laminate molding machine manufactured by Modern Machinery, under conditions of die width: 500 mm, molding temperature: 300 ° C., and processing speed of 100 m / min. Anchor a solution prepared by mixing a 15 μm thick biaxially stretched nylon film (N4142 manufactured by Toyobo Co., Ltd.) with an isocyanate anchor coating agent (Takelac A3210 / Takenate A3075 / ethyl acetate 3: 1: 28) manufactured by Mitsui Chemicals, Inc. Coating was performed with a coating roll, and while the ozone was blown at the laminating portion, the extrusion amount was adjusted so that various polyethylene resins had a thickness of 25 μm, and an intermediate layer was formed. Furthermore, on the surface of the polyethylene resin composition of the intermediate layer, using the above molding machine, Kernel KC570S (MFR 10 g / 10 min, density 0.906 g / cm ³ ) manufactured by Nippon Polyethylene Co., Ltd. was extruded resin temperature 280 ° C., take-off speed 100 m. A laminated film was prepared by laminating a coating thickness of 25 μm at a rate of / min. The laminated film B after processing was aged for 48 hours in an oven at 40 ° C., and then slit to a width of 100 mm to obtain a packaging film for evaluation.
Table 2 shows the blending ratios and evaluation results of the resin compositions of Examples 1 to 3 and Comparative Examples 1 to 4.

(Evaluation)
Examples 1 to 3 using the method for producing a packaging film of the present invention are excellent in bag breaking strength, low-temperature sealing property and heat resistance, and can be filled with high-speed liquid in a wide range from low temperature to high temperature.
On the other hand, in Comparative Examples 1 to 3 using the ethylene / α-olefin copolymer (A) and the high-pressure low-density polyethylene (B) as in the examples, the storage elastic modulus (E ′ ₁₀₀ , E ′ ₁₁₀ , Any one of E ′ ₁₀₀ -E ′ ₁₁₀ ) does not satisfy the predetermined range, and thus the heat resistance and the bag breaking strength are excellent, but the low temperature sealing property is poor. In Comparative Example 4 using only the high-pressure method low-density polyethylene (B), the low-temperature sealing property is excellent, but the bag breaking strength and the heat resistance are inferior.
Furthermore, also in the examples, the storage elastic modulus (E ′ ₁₀₀ , E ′ ₁₁₀ ) is adjusted by adjusting the blending ratio of the ethylene / α-olefin and the high-pressure method low-density polyethylene, so that the The heat resistance can be improved, and the low temperature sealability can be improved as in the third embodiment.
Example 1: Although it is excellent in bag breaking strength and heat resistance, it is slightly inferior in low-temperature sealing property.
Example 2: Excellent bag breaking strength and heat resistance, but slightly inferior in low-temperature sealability.
Example 3: Excellent bag breaking strength and low-temperature sealing property, but poor heat resistance.
Comparative Example 1: Excellent bag breaking strength and heat resistance, but poor in low-temperature sealability.
Comparative Example 2: Excellent bag breaking strength and heat resistance, but poor in low-temperature sealability.
Comparative Example 3: Excellent bag breaking strength and heat resistance, but poor in low-temperature sealability.
Comparative Example 4: Excellent low-temperature sealing property, but poor bag breaking strength and heat resistance.

  The packaging film produced according to the present invention has excellent bag breaking strength and low-temperature sealability, and enables high-speed liquid filling in a wide temperature range from low temperature to high temperature. High-speed filling becomes possible, and in particular, it is suitably used as a packaging material for containing fluid such as liquid, fiber, powder and other solid insoluble materials, fluids such as viscous bodies as contents.

Claims (5)

At least a base material layer, an intermediate layer, and a sealant layer are laminated in this order, and a manufacturing method of a packaging film used for a die roll type automatic filling machine,
The intermediate layer is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms (A) of 90 to 50% by weight and a melt flow ratio (MFR: 190 ° C., 21.18N load) of 10 to 30 g / 10. The high-pressure method low-density polyethylene (B) is composed of a polyethylene resin composition (C) consisting of 10 to 50% by weight, and is prepared so as to satisfy the following conditions (1) to (3): A method for producing a packaging film.
(1) The storage elastic modulus (E ′ ₁₀₀ ) measured at 100 ° C. is 12.0 to 13.5 MPa.
(2) The storage elastic modulus (E ′ ₁₁₀ ) measured at 110 ° C. is 1.5 to 4.0 MPa.
(3) E ′ ₁₀₀ (unit MPa) and E ′ ₁₁₀ (unit MPa) have the following relationship.
9.5 ≦ E ′ ₁₀₀ −E ′ ₁₁₀ ≦ 11.0   The method for producing a packaging film according to claim 1, wherein the polyethylene resin composition (C) constituting the intermediate layer has a melt flow ratio (MFR) of 0.1 to 100 g / 10 minutes.   The method for producing a packaging film according to claim 1 or 2, wherein the MFR of the ethylene / α-olefin copolymer (A) is smaller than the MFR of the high-pressure low-density polyethylene (B).   The method for producing a packaging film according to any one of claims 1 to 3, wherein the ethylene / α-olefin copolymer (A) is obtained using a metallocene catalyst.   The method for producing a packaging film according to any one of claims 1 to 4, wherein the filling and packaging form of the automatic filling machine is a three-way seal.