WO2024070720A1

WO2024070720A1 - Multilayer film

Info

Publication number: WO2024070720A1
Application number: PCT/JP2023/033477
Authority: WO
Inventors: 知也村上; 淳尾留川; 智也大川
Original assignee: 株式会社プライムポリマー
Priority date: 2022-09-27
Filing date: 2023-09-14
Publication date: 2024-04-04

Abstract

The present invention provides a multilayer film which has improved appearance (particularly, with fewer wrinkles), specifically, a multilayer film which is improved in terms of the degree of occurrence of wrinkles, thereby having fewer wrinkles.　This multilayer film comprises: an unstretched polypropylene film which contains a propylene polymer that satisfies requirements (i) to (iii); and an inorganic oxide layer which is in contact with the film.　(i) The melt flow rate (MFR) as measured at 230°C under a load of 2.16 kgf is within the range of 3 g/10 minutes to 25 g/10 minutes. (ii) The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) as determined by GPC is within the range of 6 to 15. (iii) The ratio (Mz/Mn) of the Z-average molecular weight (Mz) to the number average molecular weight (Mn) as determined by GPC is within the range of 40 to 150.

Description

Laminated Film

The present invention relates to a laminated film, and more specifically to a laminated film having a polypropylene film and an inorganic oxide layer.

Propylene-based polymers are widely used as materials for various molded products (e.g., Patent Documents 1 and 2). For example, films made of propylene-based polymers are widely used as packaging films for food and miscellaneous goods, taking advantage of their excellent mechanical properties such as rigidity, and optical properties such as gloss. In addition, unstretched polypropylene films are known to have a good balance of rigidity and heat resistance.

In order to preserve food for long periods of time, it is necessary to use packaging materials with excellent gas barrier properties to block oxygen and water vapor from the outside air, which promote spoilage and deterioration. Traditionally, materials with gas barrier properties have included aluminum foil, aluminum vapor deposition film, polyvinylidene chloride coated film, and ethylene vinyl alcohol film, but with the spread of environmental regulations in recent years, the use of materials that produce incineration residues, such as aluminum foil, has been restricted. Additionally, aluminum foil and aluminum vapor deposition film have problems in that the contents cannot be seen and they cannot be heated in a microwave oven.

On the other hand, a transparent gas barrier film is known in which oxides such as silicon oxide and aluminum oxide are vapor-deposited onto a non-oriented polypropylene film (see, for example, Patent Documents 3 and 4). This film has the advantages of having excellent gas barrier properties, being environmentally friendly, allowing the contents to be checked, and being suitable for use in microwave ovens.

JP 2001-302858 A JP 2006-045446 A Japanese Patent Application Laid-Open No. 9-156021 Japanese Patent Application Laid-Open No. 9-143294

However, conventional metal oxide-deposited non-oriented polypropylene films have room for further improvement in terms of appearance (i.e., many wrinkles).
Therefore, an object of the present invention is to provide a laminated film with improved appearance (i.e., fewer wrinkles).

As a result of extensive research, the inventors discovered that the appearance of a non-oriented polypropylene film can be improved by using a propylene-based polymer that satisfies requirements (i) to (iii), and thus completed the present invention.

The present invention relates to, for example, the following [1] to [5].
[1]
A laminate film comprising a non-stretched polypropylene film containing a propylene-based polymer satisfying the following requirements (i) to (iii) and an inorganic oxide layer in contact with the film:
(i) the melt flow rate (MFR) measured under conditions of 230°C and a load of 2.16 kgf is in the range of 3 to 25 g/10 min;
(ii) the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC is in the range of 6 to 15;
(iii) The ratio (Mz/Mn) of Z-average molecular weight (Mz) to number-average molecular weight (Mn) measured by GPC is in the range of 40 to 150.

[2]
The laminate film according to [1], which has gas barrier properties.

[3]
The laminated film according to [1] or [2], having a tensile modulus at 80° C. of 800 MPa or more.

[4]
The laminate film according to any one of [1] to [3], wherein the inorganic oxide layer has a thickness of 20 to 150 nm.

[5]
The laminated film according to any one of [1] to [4], further comprising a biaxially oriented polypropylene film on the opposite side to the non-oriented polypropylene film via an adhesive layer in contact with the inorganic oxide layer.

The present invention provides a laminated film with improved appearance (i.e., fewer wrinkles). In other words, a laminated film with fewer wrinkles is provided, with improvements in the degree of wrinkle formation.

The present invention will now be described in further detail.
[Laminated film]
The laminated film of the present invention comprises a non-oriented polypropylene film (hereinafter referred to as "CPP film") and an inorganic oxide layer in contact with the CPP film.

[CPP film]
(Propylene-based polymer)
The CPP film contains a propylene-based polymer that satisfies the following requirements (i) to (iii).
Requirement (i):
The melt flow rate (MFR) measured at 230° C. under a load of 2.16 kgf is 3 to 25 g/10 min, preferably 4 to 23 g/10 min, and more preferably 4 to 22 g/10 min.
On the other hand, if the MFR is lower than the lower limit, the smoothness and gas barrier properties of the formed film are reduced, and if the MFR is higher than the upper limit, the discharge amount from the extruder during film formation is reduced, resulting in reduced productivity.

Requirement (ii):
The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), measured by GPC (gel permeation chromatography) under the conditions employed in the examples described later, is in the range of 6 to 15, preferably 7 to 15, and more preferably 7 to 14.
On the other hand, if the Mw/Mn is too small below the lower limit, the elastic modulus of the film produced is insufficient, and if the Mw/Mn is too large above the upper limit, the smoothness of the film produced is reduced.

Requirement (iii):
The ratio (Mz/Mn) of Z-average molecular weight (Mz) to number-average molecular weight (Mn) measured by GPC is in the range of 40-150, preferably 40-140, and more preferably 40-135.
On the other hand, if the Mz/Mn ratio is too small compared to the lower limit, the elastic modulus of the film formed is insufficient, whereas if the Mz/Mn ratio is too large compared to the upper limit, the smoothness of the film formed is reduced.

In the present invention, the above requirements (ii) and (iii) are satisfied, that is, a propylene-based polymer with a wide molecular weight distribution is used, and the degree of orientation of the propylene-based polymer molecules in the MD direction of molding is increased during film molding, resulting in a high film rigidity. In addition, the orientation promotes crystallization of the propylene-based polymer, improving the heat resistance of the film. As a result, it is presumed that the rigidity of the film is maintained during deposition processing at high processing temperatures, resulting in a laminated film with excellent appearance, i.e., a CPP film with an inorganic oxide layer.

Examples of the propylene-based polymer include propylene homopolymers, propylene copolymers, and mixtures thereof. Examples of the mixture include a mixture of multiple types of propylene-based homopolymers, a mixture of multiple types of propylene-based copolymers, and a mixture of one or more types of propylene-based homopolymers and one or more types of propylene-based copolymers. In the case of a mixture, it is sufficient that the mixture as a whole satisfies the above requirements (i) to (iii), and each of the components contained in the mixture does not necessarily have to satisfy the above requirements (i) to (iii).

A preferred embodiment of the propylene-based polymer is a propylene homopolymer. The laminate film of the present invention obtained from a propylene homopolymer that satisfies the above requirements (i) to (iii) has excellent appearance, i.e., has few wrinkles.

Another preferred embodiment of the propylene-based polymer is a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene).
Examples of the α-olefin include ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. The α-olefin may be used alone or in combination.

In the copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene), the content of structural units derived from propylene is preferably 90% by mass or more, more preferably 92% by mass or more, even more preferably 96% by mass or more, still more preferably more than 98% by mass, and particularly preferably 98.6% by mass or more, and the content of structural units derived from an α-olefin having 2 to 8 carbon atoms (excluding propylene) is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 4% by mass or less, still more preferably less than 2% by mass, and particularly preferably 1.4% by mass or less. The content can be measured by ¹³ C-NMR.
The laminated film of the present invention obtained from a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene), in which the content ratio of structural units derived from an α-olefin having 2 to 8 carbon atoms (excluding propylene) is within the above-mentioned range, has excellent appearance, i.e., has few wrinkles.

The propylene homopolymer and the copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene) may each contain at least one or more biomass-derived monomers (propylene, an α-olefin having 2 to 8 carbon atoms (excluding propylene)). The same type of monomer constituting the polymer may be only a biomass-derived monomer, may be only a fossil fuel-derived monomer, or may contain both a biomass-derived monomer and a fossil fuel-derived monomer. The biomass-derived monomer is a monomer made from any renewable natural raw material, such as a plant-derived or animal-derived monomer, including fungi, yeast, algae, and bacteria, and its residue, which contains about 1×10 ⁻¹² of ¹⁴ C isotope as carbon and has a biomass carbon concentration (pMC) of about 100 (pMC) measured in accordance with ASTM D6866. The biomass-derived monomer (propylene, an α-olefin having 2 to 8 carbon atoms (excluding propylene)) can be obtained, for example, by a conventionally known method. It is preferable that the homopolymer and/or the copolymer contain a biomass-derived monomer from the viewpoint of reducing the environmental load. If the polymer production conditions, such as the polymerization catalyst and polymerization temperature, are the same, even if the raw olefin is a propylene-based polymer containing a biomass-derived olefin, the molecular structure other than the inclusion of ^14C isotope at a ratio of about 1×10 ⁻¹² is the same as that of a propylene-based polymer made of a fossil fuel-derived monomer. Therefore, the performance is said to be the same.

The propylene homopolymer and the copolymer of propylene and α-olefin having 2 to 8 carbon atoms (excluding propylene) may each contain at least one or more chemically recycled monomers (propylene, α-olefin having 2 to 8 carbon atoms (excluding propylene)). The same type of monomer constituting the polymer may be only chemically recycled monomers, or may contain chemically recycled monomers and fossil fuel-derived monomers and/or biomass-derived monomers. The chemically recycled monomers (propylene, α-olefin having 2 to 8 carbon atoms (excluding propylene)) can be obtained, for example, by a conventionally known method. It is preferable from the viewpoint of reducing the environmental load (mainly reducing waste) that the homopolymer and/or the copolymer contain chemically recycled monomers. Chemically recycled monomers are monomers obtained by depolymerizing or pyrolyzing polymers such as waste plastics back into monomer units such as propylene, as well as monomers produced using such monomers as raw materials. Therefore, even if the raw material monomer is a propylene-based polymer containing a monomer derived from chemical recycling, if the polymer production conditions such as the polymerization catalyst, polymerization process, and polymerization temperature are the same, the molecular structure will be the same as a propylene-based polymer made from a monomer derived from fossil fuels. Therefore, the performance is said to be the same.

A preferred example of the propylene-based polymer is a propylene-based polymer composition (X) containing a propylene homopolymer (A) and a propylene-based polymer (B) as described below.

<Propylene homopolymer (A)>
The melt flow rate (MFR) of the propylene homopolymer (A) measured under conditions of 230° C. and a load of 2.16 kgf is preferably in the range of 5 to 40 g/10 min, more preferably 7 to 35 g/10 min.

The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the propylene homopolymer (A) is preferably in the range of 3.0 to 8.0, more preferably 3.5 to 6.0.
When the Mw/Mn of the propylene homopolymer (A) is within the above range, the laminate film of the present invention is excellent in rigidity and transparency.

<<Method for producing propylene homopolymer (A)>>
The propylene homopolymer (A) can be produced by homopolymerizing propylene using a catalyst, and may be a commercially available product.

Examples of the catalyst include catalysts formed from a solid catalyst component having magnesium, titanium, and a halogen as essential components, an organometallic compound catalyst component such as an organoaluminum compound, and an electron donor compound catalyst component such as an organosilicon compound (representative examples are the catalysts described in paragraphs [0050] to [0075] of WO 2021/025142); and metallocene catalysts that use a metallocene compound as one of the catalyst components.

<Propylene-Based Polymer (B)>
The propylene polymer (B) contains 20 to 50 mass % of a propylene polymer (b1) having an intrinsic viscosity [η] of 8 to 12 dL/g measured in tetralin solvent at 135° C., and 50 to 80 mass % of a propylene polymer (b2) having an intrinsic viscosity [η] of 0.5 to 1.5 dL/g measured in tetralin solvent at 135° C. (wherein the total amount of (b1) and (b2) is 100 mass %).
Hereinafter, the intrinsic viscosity [η] measured at 135° C. in a tetralin solvent will be simply referred to as “intrinsic viscosity [η]”.

<Propylene polymer (b1)>
The intrinsic viscosity [η] of the propylene polymer (b1) is in the range of 8 to 12 dL/g, preferably in the range of 10 to 12 dL/g, and more preferably in the range of 10.5 to 11.5 dL/g.

When the intrinsic viscosity [η] is equal to or greater than the lower limit, the laminated film of the present invention has excellent rigidity and heat resistance. When the intrinsic viscosity [η] is equal to or less than the upper limit, a CPP film can be produced with excellent moldability, and the laminated film of the present invention has excellent surface appearance.

The mass fraction of the propylene-based polymer (b1) in the propylene-based polymer (B) is in the range of 20 to 50 mass%, preferably 20 to 45 mass%, more preferably 20 to 40 mass%, and even more preferably 22 to 40 mass%.

When the mass fraction is equal to or greater than the lower limit, the propylene-based polymer composition (X) has sufficient melt tension, and a CPP film having excellent rigidity and heat resistance can be produced. When the mass fraction is equal to or less than the upper limit, the occurrence of defective appearance during molding of the propylene-based polymer composition (X) can be suppressed.

The propylene-based polymer (b1) may be, for example, a homopolymer of propylene or a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene). Examples of the α-olefin having 2 to 8 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Of these α-olefins, ethylene is preferred. One or more types of α-olefins may be used.

In a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of structural units derived from propylene is usually 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more, and the content of structural units derived from an α-olefin having 2 to 8 carbon atoms (excluding propylene) is usually 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. The above content can be measured by ¹³ C-NMR.
The propylene-based polymer (b1) may be used alone or in combination.

<Propylene polymer (b2)>
The intrinsic viscosity [η] of the propylene polymer (b2) is in the range of 0.5 to 1.5 dL/g, preferably 0.6 to 1.5 dL/g, and more preferably 0.8 to 1.5 dL/g.

When the intrinsic viscosity [η] is equal to or greater than the lower limit, sufficient melt tension can be imparted to the propylene-based polymer (B), and when the intrinsic viscosity [η] is equal to or less than the upper limit, a CPP film with excellent moldability can be produced.

The mass fraction of the propylene-based polymer (b2) in the propylene-based polymer (B) is in the range of 50 to 80 mass%, preferably 55 to 80 mass%, more preferably 60 to 80 mass%, and even more preferably 60 to 78 mass%.

When the mass fraction is equal to or greater than the lower limit, the occurrence of defective appearance during molding of the propylene-based polymer composition (X) can be suppressed. When the mass fraction is equal to or less than the upper limit, sufficient melt tension can be imparted to the propylene-based polymer (B), and the laminate film of the present invention has excellent rigidity and heat resistance.

The propylene-based polymer (b2) may be, for example, a homopolymer of propylene or a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene). Examples of the α-olefin having 2 to 8 carbon atoms include ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Of these α-olefins, ethylene is preferred. One or more types of α-olefins may be used.

In a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, the content of structural units derived from propylene is usually 90% by mass or more, preferably 93% by mass or more, and more preferably 94% by mass or more, and the content of structural units derived from an α-olefin having 2 to 8 carbon atoms (excluding propylene) is usually 10% by mass or less, preferably 7% by mass or less, and more preferably 6% by mass or less. The above content can be measured by ¹³ C-NMR.
The propylene-based polymer (b2) may be used alone or in combination of two or more.

Additives
The propylene-based polymer (B) may contain additives such as antioxidants, neutralizing agents, flame retardants, and crystal nucleating agents, if necessary. One or more additives may be used. The proportion of the additives is not particularly limited and may be appropriately adjusted.

<Physical properties of propylene polymer (B)>
The propylene polymer (B) has a melt flow rate (MFR) measured at 230° C. under a load of 2.16 kgf in the range of preferably 0.01 to 5 g/10 min, more preferably 0.05 to 4 g/10 min, and further preferably 0.1 to 3 g/10 min. When the propylene polymer (B) has an MFR in the above range, the propylene polymer composition (X) has excellent film formability.

The propylene-based polymer (B) has an area ratio of a high molecular weight region having a molecular weight of 1.5 million or more (corresponding to the mass ratio of high molecular weight components having a molecular weight of 1.5 million or more) of the total area surrounded by a molecular weight distribution curve measured by gel permeation chromatography (GPC) of preferably 7% or more, more preferably 10% or more, and even more preferably 12% or more. The upper limit of the area ratio is, for example, 30%, preferably 25%.

The fact that the area ratio of the high molecular weight region is equal to or greater than a specific ratio means that the propylene-based polymer (B) contains high molecular weight components with a molecular weight of 1.5 million or more. At least a portion of these high molecular weight components has an intrinsic viscosity [η] of 10 to 12 dL/g. Therefore, if the ratio of the high molecular weight components is within the above range, the melt tension of the propylene-based polymer (B) will be superior.

The propylene-based polymer (B) preferably has two peaks in the molecular weight distribution curve measured by GPC. Here, the ratio (MH/ML) of the peak molecular weight (MH) on the high molecular weight side to the peak molecular weight (ML) on the low molecular weight side is preferably 50 or more, more preferably 70 or more, and even more preferably 90 or more. The upper limit of the ratio (MH/ML) is, for example, 500, preferably 300. The fact that the molecular weight distribution curve has two peaks and MH/ML is a specific value or more indicates that the polymer contains a large amount of high molecular weight components and that the intrinsic viscosity [η] is also high. Therefore, the propylene-based polymer (B) of such an embodiment contributes to improving the melt tension and improving the rigidity and heat resistance of the film formed from the propylene-based polymer composition (X).

The propylene-based polymer (B) has a peak molecular weight ML on the low molecular weight side of the molecular weight distribution curve measured by GPC, from the viewpoints of viscosity and film formability of the propylene-based polymer composition (X), of preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 50,000 or less.

<<Method for producing propylene polymer (B)>>
Examples of the production method of the propylene-based polymer (B) include various known production methods, such as those described in paragraphs [0038] to [0075] of WO 2021/025142.

<Propylene-Based Polymer Composition (X)>
The propylene polymer composition (X) contains the propylene homopolymer (A) and the propylene polymer (B) in such proportions that the entire composition satisfies the requirements (i) to (iii), for example, 60 to 99 mass %, preferably 70 to 99 mass %, more preferably 70 to 97 mass %, and even more preferably 70 to 95 mass % of the propylene homopolymer (A) and 1 to 40 mass %, preferably 1 to 30 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 30 mass % of the propylene polymer (B) (wherein the total amount of (A) and (B) is 100 mass %).

When the proportion of the propylene polymer (B) is at least the lower limit, the resulting CPP film and the laminate film of the present invention are excellent in rigidity (tensile modulus).
When the proportion of the propylene polymer (B) is equal to or less than the upper limit, the resulting CPP film and the laminate film of the present invention are excellent in transparency and appearance.

Since the molecular weight of the propylene-based polymer (b1) is high, by mixing the propylene homopolymer (A) and the propylene-based polymer (B), it is possible to prepare a propylene-based polymer composition (X) that satisfies the requirements (ii) and (iii), i.e., has a wide molecular weight distribution.

<<Method for producing propylene polymer composition (X)>>
The propylene polymer composition (X) can be produced by adopting any known method. For example, there can be mentioned a method in which the propylene homopolymer (A), the propylene polymer (B), and, if necessary, additives are mixed using a Henschel mixer, a V-type blender, a ribbon blender, a tumbler blender, or the like, or a method in which the mixture is melt-kneaded using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, a roll, or the like, and then granulated or pulverized.

(Additive)
The CPP film may contain additives such as weather resistance stabilizers, heat resistance stabilizers, antistatic agents, slip agents, antiblocking agents, antifogging agents, nucleating agents, decomposition agents, pigments, dyes, plasticizers, hydrochloric acid absorbers, antioxidants, crosslinking agents, crosslinking accelerators, reinforcing agents, fillers, softeners, processing aids, activators, moisture absorbents, adhesives, flame retardants, release agents, etc. One or more additives may be used.

The CPP film may contain a nucleating agent to improve transparency, heat resistance, etc. Examples of nucleating agents include sorbitol compounds such as dibenzylidene sorbitol, organic phosphate compounds, rosin acid salt compounds, C4 to C12 aliphatic dicarboxylic acids and metal salts thereof. Of these, organic phosphate compounds are preferred. One or more types of nucleating agents may be used.

The amount of the nucleating agent in the CPP film is preferably 0.05 to 0.5 parts by mass, and more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of the propylene-based polymer.

The CPP film may contain a resin component other than the propylene-based polymer (e.g., polyethylene), but the amount of the resin component is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of the propylene-based polymer.

(CPP film)
The CPP film can be produced by forming the propylene-based polymer into a film.
Examples of the molding method include extrusion molding methods such as a T-die method and an inflation method, compression molding, calendar molding, and casting.

The CPP film can be formed, for example, as follows.
The propylene-based polymer and any additives may be directly charged into a hopper or the like of a film-forming machine, or the components may be mixed in advance using a ribbon blender, a Banbury mixer, a Henschel mixer, a super mixer or the like, or may be melt-kneaded using a kneader such as a single-screw or twin-screw extruder or a roll to obtain a propylene-based polymer, which may then be molded into a film.

A specific example of the production of a CPP film will be described using the T-die method. The above-mentioned components are fed into an extruder and melt-kneaded usually at a temperature of 180 to 280°C, preferably 200 to 270°C, and then extruded into a film from the die lip of a T-die. The molten film is cooled and taken up by a take-up machine such as a nip roll to obtain a CPP film.
Methods for cooling the molten film include, for example, cooling methods using rolls and air cooling such as the air knife method or the air chamber method, narrow pressure cooling methods such as the polishing roll method, swing roll method and belt casting method, and contact cooling with a refrigerant such as the water cooling method.
The obtained CPP film may be subjected to a film treatment method generally used in film molding, such as a corona discharge treatment or a liquid coating treatment.

<Inorganic oxide layer>
The laminate film of the present invention has an inorganic oxide layer.
The inorganic oxide layer can be formed by vapor deposition of an inorganic oxide onto the CPP film.
Examples of deposition methods include conventional methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD).
Examples of the inorganic oxide include inorganic oxides of aluminum, zinc, magnesium, silicon, and the like.
The thickness of the inorganic oxide layer, as measured by the method employed in the examples described below, is, for example, 20 to 150 nm, and preferably 30 to 60 nm. When the thickness is in the above range, the laminated film of the present invention has excellent appearance and gas barrier properties.

[Laminated film]
The laminated film of the present invention has the CPP film and the inorganic oxide layer in contact with the CPP film.

The laminate film of the present invention preferably has excellent gas barrier properties such as water vapor barrier properties and oxygen gas barrier properties.
The water vapor transmission rate is preferably not more than 5, and more preferably not more than 1. This water vapor transmission rate can be adjusted, for example, by changing the thickness of the deposited film.
The oxygen gas permeability is preferably not more than 1000, more preferably not more than 100. It can be adjusted by changing the thickness of the deposited film.

The tensile modulus of the laminated film of the present invention at 80°C, measured by the method employed in the examples described below, is preferably 800 MPa or more, more preferably 850 MPa or more, and the upper limit may be, for example, 1300 MPa. This tensile modulus value can be adjusted, for example, by changing the film take-up speed during film formation.

The laminated film of the present invention may have an optional layer in addition to the CPP film and the inorganic oxide layer. By having the optional layer, various functions can be imparted to the laminated film of the present invention. The optional layer may be one or more.
The optional layer may be provided in the following locations:
A location on the side of the CPP film opposite the inorganic oxide layer A location between the CPP film and the inorganic oxide layer, where the CPP film and the inorganic oxide layer are not in contact with each other A location on the side of the inorganic oxide layer opposite the CPP film

Examples of the optional layer include a biaxially oriented polypropylene film, a CPP film (which may be a CPP film containing a propylene-based polymer satisfying the above-mentioned requirements (i) to (iii), or a different CPP film), a barrier layer against gases such as water vapor and oxygen, a sound absorbing layer, a light shielding layer, an adhesive layer, a pressure sensitive adhesive layer, a colored layer, a conductive layer, and a recycled resin-containing layer.
Specific examples of materials for forming the optional layers include olefin polymer compositions other than the propylene polymers, gas barrier resin compositions, and adhesive resin compositions.
Methods for forming the optional layers include, for example, coextrusion and extrusion coating.
It is preferable to have a biaxially oriented polypropylene film as an optional layer, and a preferred embodiment of the laminated film of the present invention is to have a biaxially oriented polypropylene film on the opposite side to the non-oriented polypropylene film via an adhesive layer in contact with the inorganic oxide layer. Examples of the adhesive layer include an anchor coating agent such as a urethane-based or isocyanate-based adhesive, and an adhesive resin such as a modified polyolefin such as an unsaturated carboxylic acid grafted polyolefin. The above laminated film is preferable from the viewpoint of mono-materialization and reduction of environmental load, compared with a laminated film having a biaxially oriented polyethylene terephthalate film, a biaxially oriented nylon film, or the like as a biaxially oriented film.

The laminated film of the present invention is used as a packaging material for, for example, foods, beverages, industrial parts, miscellaneous goods, toys, daily necessities, office supplies, medical supplies, and the like.
The laminated film of the present invention can be used as a packaging film in a wide range of packaging fields, including, for example, packaging various foods such as fresh foods such as fish meat, dried foods such as snacks and noodles, and water-based foods such as soups and pickles; packaging medical products such as medical products in various forms such as tablets, powders, and liquids, and medical peripheral materials; and packaging various electrical devices such as cassette tapes and electrical components.

Hereinafter, one embodiment of the present invention will be described with reference to examples, but the present invention is not limited to these examples.
(Measurement and Evaluation of Propylene Polymers)
[Weight average molecular weight (Mw), number average molecular weight (Mn), Z average molecular weight (Mz) and molecular weight distribution (Mw/Mn, Mz/Mn)]
The weight average molecular weight (Mw), number average molecular weight (Mn), Z average molecular weight (Mz) and molecular weight distribution (Mw/Mn, Mz/Mn) were measured using GPC under the following conditions. The weight average molecular weight (Mw), number average molecular weight (Mn) and Z average molecular weight (Mz) were calculated based on the following conversion method using a calibration curve prepared using commercially available monodisperse standard polystyrene.
(Measurement condition)
Apparatus: Gel permeation chromatograph HLC-8321 GPC/HT type (manufactured by Tosoh Corporation)
Organic solvent: o-dichlorobenzene Column: 2 TSKgel GMH6-HT columns, 2 TSKgel GMH6-HTL columns (both manufactured by Tosoh Corporation)
Flow rate: 1.0 mL/min Sample: 0.10 mg/mL o-dichlorobenzene solution Temperature: 140° C.
Molecular weight conversion: PS conversion/universal calibration method For the calculation of universal calibration, the coefficients of the Mark-Houwink viscosity equation were used. The Mark-Houwink coefficients of PS were the values described in the literature (J. Polym. Sci., Part A-2, 8, 1803 (1970)).

[Production of Propylene Homopolymer (A)]
[Production of Propylene Homopolymer (A-1)]
[Production Example 1]
(1) Preparation of transition metal catalyst component (c-1) A vibration mill equipped with four grinding pots with an internal volume of 4 L containing 9 kg of steel balls with a diameter of 12 mm was prepared. 300 g of magnesium chloride, 115 mL of diisobutyl phthalate, and 60 mL of titanium tetrachloride were added to each pot in a nitrogen atmosphere, and the magnesium chloride was ground over 40 hours. 75 g of the resulting mixture was placed in a 5 L flask, and 1.5 L of toluene was added and the mixture was stirred at 114°C for 30 minutes, then allowed to stand and the supernatant liquid was removed. The resulting solid was washed three times with 1.5 L of n-heptane at 20°C. It was further dispersed in 1.5 L of n-heptane to obtain a slurry of transition metal catalyst component (c-1). The resulting transition metal catalyst component (c-1) contained 2 wt% titanium and 18 wt% diisobutyl phthalate.

(2) Production of prepolymerized catalyst (d-1) 100 g of transition metal catalyst component (c-1), 15.4 mL of triethylaluminum, and 100 L of heptane were charged into a 200 L autoclave equipped with a stirrer, and 600 g of propylene was charged while maintaining the internal temperature at 5°C, and propylene was polymerized for 60 minutes while stirring. After the polymerization was completed, 4.1 mL of titanium tetrachloride was charged to obtain a prepolymerized catalyst (d-1). This prepolymerized catalyst (d-1) contained 6 g of polypropylene per 1 g of the transition metal catalyst component.

(3) Production of Propylene Homopolymer (A-1) To a 500 L stirred vessel polymerization reactor, 130 kg/hour of propylene, 136 NL/hour of hydrogen, 1.05 g/hour of prepolymerization catalyst (d-1), 5.2 mL/hour of triethylaluminum, and 0.4 mL/hour of cyclohexylmethyldimethoxysilane were continuously fed, and hydrogen was fed so that the hydrogen concentration in the gas phase was 2.6 mol%. The temperature of the stirred vessel polymerization reactor was 73°C, and the pressure was 3.2 MPa/G. The obtained slurry was deactivated, and then propylene was evaporated to obtain a powdery propylene homopolymer (a-1). The obtained propylene homopolymer (a-1) had an MFR of 1.7 g/10 min. To 100 parts by mass of the obtained propylene homopolymer (a-1), 0.07 parts by mass of organic peroxide Perhexa 25B-40 (NOF Corporation) was added and thoroughly stirred. This was melt-kneaded using a KTX 30 mm twin-screw extruder at a cylinder temperature of 230° C. and an extrusion rate of 25 kg/hour. The obtained propylene homopolymer (A-1) had an MFR of 9 g/10 min and an Mw/Mn of 3.7.

[Production of Propylene Homopolymer (A-2)]
[Production Example 2]
(1) Preparation of solid titanium catalyst component (c-2) 95.2 g of anhydrous magnesium chloride, 442 mL of decane, and 390.6 g of 2-ethylhexyl alcohol were reacted at 130°C for 2 hours to obtain a homogeneous solution, and then 21.3 g of phthalic anhydride was added to the solution, and the mixture was stirred and mixed at 130°C for 1 hour to dissolve the phthalic anhydride. The homogeneous solution thus obtained was cooled to room temperature, and then 75 mL of the homogeneous solution was added dropwise over 1 hour to 200 mL of titanium tetrachloride kept at -20°C. After the addition, the temperature of the mixture was raised to 110°C over 4 hours, and when it reached 110°C, 5.22 g of diisobutyl phthalate (DIBP) was added, and the mixture was stirred and maintained at the same temperature for 2 hours. After the 2-hour stirring, the solid portion was collected by hot filtration, and the solid portion was resuspended in 275 mL of titanium tetrachloride, and then heated again at 110°C for 2 hours. After the reaction was completed, the solid portion was collected by hot filtration again and thoroughly washed with decane and hexane at 110°C until no free titanium compounds were detected in the solution. The solid titanium catalyst component prepared as above was stored as a hexane slurry, and a portion of this was dried to examine the catalyst composition. The solid titanium catalyst component contained titanium in the amounts of 2.3 wt%, chlorine in the amount of 61 wt%, magnesium in the amount of 19 wt%, and DIBP in the amount of 12.5 wt%.

(2) Production of prepolymerized catalyst (d-2) 100.0 g of solid titanium catalyst component (c-2), 19.2 mL of cyclohexylmethyldimethoxysilane, 65.6 mL of triethylaluminum, and 10 L of heptane were charged into a 20 L autoclave equipped with a stirrer, and 600 g of propylene was charged while maintaining the internal temperature at 15 to 20°C, and propylene was polymerized while stirring for 100 minutes. After the polymerization was completed, the solid component was allowed to settle, and the supernatant was removed and washed with heptane twice. The obtained prepolymerized catalyst was resuspended in purified heptane, and the concentration of the solid catalyst component was adjusted to 1.0 g/L with heptane.

(3) Production of propylene homopolymer (A-2) To a tubular polymerization vessel having a capacity of 58 L, propylene was continuously supplied at 43 kg/hour, hydrogen at 56 NL/hour, prepolymerization catalyst (d-2) at 0.77 g/hour, triethylaluminum at 2.3 mL/hour, and cyclohexylmethyldimethoxysilane at 4.3 mL/hour, and polymerization was performed in a liquid-filled state in which no gas phase was present. The temperature of the tubular polymerization vessel was 70°C, and the pressure was 3.4 MPa/G. The obtained slurry was sent to a vessel polymerization vessel having a capacity of 70 L equipped with a stirrer, and further polymerization was performed. To the polymerization vessel, propylene was continuously supplied at 45 kg/hour, and hydrogen was supplied so that the hydrogen concentration in the gas phase was 2.9 mol%. Polymerization was performed at a polymerization temperature of 70°C and a pressure of 3.1 MPa/G. After the obtained slurry was deactivated, propylene was evaporated to obtain a powdery propylene homopolymer (A-2). The resulting propylene homopolymer (A-2) had an MFR of 9 g/10 min and an Mw/Mn of 5.0.

[Production of Propylene Homopolymer (A-3)]
[Production Example 3]
(1) Preparation of solid titanium catalyst component (c-3) 95.2 g of anhydrous magnesium chloride, 442 mL of decane, and 390.6 g of 2-ethylhexyl alcohol were reacted at 130°C for 2 hours to obtain a homogeneous solution, and then 21.3 g of phthalic anhydride was added to the solution, and the mixture was stirred and mixed at 130°C for 1 hour to dissolve the phthalic anhydride. The homogeneous solution thus obtained was cooled to room temperature, and then 75 mL of the homogeneous solution was added dropwise over 1 hour to 200 mL of titanium tetrachloride kept at -20°C. After the addition, the temperature of the mixture was raised to 110°C over 4 hours, and when it reached 110°C, 5.22 g of diisobutyl phthalate (DIBP) was added, and the mixture was stirred and held at the same temperature for 2 hours. After the reaction for 2 hours was completed, the solid portion was collected by hot filtration, and the solid portion was resuspended in 275 mL of titanium tetrachloride, and then heated again at 110°C for 2 hours. After the reaction was completed, the solid portion was collected by hot filtration again and thoroughly washed with decane and hexane at 110°C until no free titanium compounds were detected in the solution. The solid titanium catalyst component prepared as above was stored as a hexane slurry, and a portion of this was dried to examine the catalyst composition. The solid titanium catalyst component contained titanium in the amounts of 2.3 wt%, chlorine in the amount of 61 wt%, magnesium in the amount of 19 wt%, and DIBP in the amount of 12.5 wt%.

(2) Production of prepolymerized catalyst (d-3) 100.0 g of solid titanium catalyst component (c-3), 22.4 mL of dicyclopentyldimethoxysilane, 65.6 mL of triethylaluminum, and 10 L of heptane were charged into a 20 L autoclave equipped with a stirrer, and 600 g of propylene was charged while maintaining the internal temperature at 15 to 20°C, and propylene was polymerized while stirring for 100 minutes. After the polymerization was completed, the solid component was allowed to settle, and the supernatant was removed and washed with heptane twice. The obtained prepolymerized catalyst was resuspended in purified heptane, and the concentration of the solid catalyst component was adjusted to 1.0 g/L with heptane.

(3) Production of propylene homopolymer (A-3) To a tubular polymerization vessel having a capacity of 58 L, propylene was continuously supplied at 43 kg/hour, hydrogen at 163 NL/hour, prepolymerization catalyst (d-3) at 0.55 g/hour, triethylaluminum at 1.9 mL/hour, and dicyclopentyldimethoxysilane at 3.8 mL/hour, and polymerization was performed in a liquid-filled state in which no gas phase was present. The temperature of the tubular polymerization vessel was 70°C, and the pressure was 3.5 MPa/G. The obtained slurry was sent to a vessel polymerization vessel having a capacity of 70 L equipped with a stirrer, and further polymerization was performed. To the polymerization vessel, propylene was continuously supplied at 45 kg/hour, and hydrogen was supplied so that the hydrogen concentration in the gas phase was 15.8 mol%. Polymerization was performed at a polymerization temperature of 63°C and a pressure of 3.2 MPaG. After the obtained slurry was deactivated, propylene was evaporated to obtain a powdery propylene homopolymer (A-3). The resulting propylene homopolymer (A-3) had an MFR of 30 g/10 min and an Mw/Mn of 5.2.

[Production of Propylene Homopolymer (A-4)]
[Production Example 4]
Propylene homopolymer (A-4) has an MFR of 7.2 g/10 min and an intrinsic viscosity [η]
A propylene homopolymer having a viscosity of 1.8 dL/g, a melting point of 165° C., and an Mw/Mn ratio of 4.8 (manufactured by Prime Polymer Co., Ltd., trade name: Prime Polypro F107BA) was used.

[Production of Propylene-Based Polymer (B)]
[Production Example 5]
Propylene-based polymer (B) was produced according to Production Example 1 of WO 2021/025142. In this Production Example 5, the propylene-based polymer (A-1), propylene-based polymer (a1-1), and propylene-based polymer (a2-1) in Production Example 1 of WO 2021/025142 are to be read as propylene-based polymer (B), propylene-based polymer (b1), and propylene-based polymer (b2), respectively.
Table 1 shows the physical properties of the propylene polymer (B) and the like measured in the same manner as in Production Example 1 of WO 2021/025142.

Comparative Example 1
(Manufacture of laminated film)
As the propylene-based polymer, the propylene homopolymer (100 parts by mass) obtained in Production Example 1 was prepared.
Using a film molding machine equipped with a 600 mm wide T-die at the tip of an extruder having a screw diameter of 75 mm and set at a temperature of 286° C., a propylene-based polymer was fed into the extruder and extruded into a film, which was then cooled with a chill roll set at a temperature of 30° C. to obtain a CPP film having a thickness of 25 μm.
A part of the obtained CPP film was cut out to prepare a test piece, and an inorganic oxide layer was formed on the surface of the remaining part by the following method.
Specifically, the formed film was cut to a width of 130 mm and set in a vacuum deposition apparatus equipped with a film unwinder and winder. After creating a vacuum of 2.3×10 ⁻² Pa, the film was wound around a cooled metal drum at −20° C. Aluminum oxide or silicon oxide was heated and evaporated to deposit an inorganic oxide on the surface of the film in contact with the cooled metal drum.
In this way, a laminated film was obtained.
Further, for the evaluation of the number of wrinkles described later, an A4 size (210 mm in the transverse (TD) direction×290 mm in the MD) laminated film was prepared.

(Measurement and evaluation of laminated films)
[Thickness of inorganic oxide layer]
The thickness of the inorganic oxide layer was measured as follows.
The obtained laminated film was cut with a microtome to expose a cross section. The cross section was observed with a scanning electron microscope (SEM) to measure the thickness of the inorganic oxide layer. The SEM observation was performed using a Hitachi High-Tech Regulus 8220 with a backscattered electron detector.

[Tensile modulus]
The tensile modulus (MPa) was measured according to the method of JIS K7161. The measurement was carried out at 60° C. and 80° C. in the extrusion direction (MD) of molding. It can be said that the higher the tensile modulus, the higher the rigidity.

〔Wrinkle〕
The laminated film was visually observed for wrinkles in the TD direction on the CPP film, and the number of wrinkles was evaluated.
The symbols in Tables 2 and 3 have the following meanings:
(Wrinkle)
○: 2 or less △: 3 to 9 ×: 10 or more

[Comparative Examples 2 to 5, Examples 1 to 7]
A laminated film was produced and evaluated in the same manner as in Comparative Example 1, except that the propylene-based polymer was changed as shown in Table 2. The results are shown in Table 2.

Comparative Examples 5-1 to 5-3
A laminate film was produced and evaluated in the same manner as in Comparative Example 5, except that the conditions for forming the inorganic oxide layer were changed to change the type of inorganic oxide and the thickness of the inorganic oxide layer.
Furthermore, the discoloration of the laminated film was also evaluated. A film without an inorganic oxide layer was prepared and placed next to the film with the inorganic oxide layer formed thereon, and the presence or absence of a difference in color was visually evaluated. The results are shown in Table 3.

[Examples 6-1 to 6-3]
A laminate film was produced and evaluated in the same manner as in Example 6, except that the conditions for forming the inorganic oxide layer were changed to change the type of inorganic oxide and the thickness of the inorganic oxide layer. In addition, the laminate film was also evaluated for discoloration. The results are shown in Table 3.

Claims

A laminate film comprising a non-stretched polypropylene film containing a propylene-based polymer satisfying the following requirements (i) to (iii) and an inorganic oxide layer in contact with the film:
(i) the melt flow rate (MFR) measured under conditions of 230°C and a load of 2.16 kgf is in the range of 3 to 25 g/10 min;
(ii) the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC is in the range of 6 to 15;
(iii) The ratio (Mz/Mn) of Z-average molecular weight (Mz) to number-average molecular weight (Mn) measured by GPC is in the range of 40 to 150.
The laminated film according to claim 1, which has gas barrier properties.
The laminated film according to claim 1, which has a tensile modulus of elasticity of 800 MPa or more at 80°C.
The laminated film according to claim 1, wherein the inorganic oxide layer has a thickness of 20 to 150 nm.
The laminated film according to claim 1 further comprises a biaxially oriented polypropylene film on the opposite side to the unoriented polypropylene film, via an adhesive layer that contacts the inorganic oxide layer.