The content of the antioxidant is 100 ppm by mass to 2000 ppm by mass, preferably 200 ppm by mass to 1500 ppm by mass, and more preferably 500 ppm by mass to 1000 ppm by mass with respect to the recycled resin composition from a viewpoint of improving an appearance and reducing a damage property.

Examples of the antistatic agent include a glycerin ester and a sorbitanoic acid ester of a fatty acid having 8 to 22 carbon atoms, an alkyl dialkanolamide of a fatty acid having 8 to 22 carbon atoms, a polyethylene glycol ester, and an alkyl diethanolamine. The antistatic agent is preferably diethanolamide. Note that the antistatic agent may be used singly or in combination of two or more types thereof.

The content of the antistatic agent is preferably 100 ppm by mass to 2000 ppm by mass, more preferably 200 ppm by mass to 1000 ppm by mass, and still more preferably 300 ppm by mass to 500 ppm by mass with respect to the recycled resin composition from a viewpoint of reducing a damage property. In addition, the content of the antistatic agent is preferably 100 ppm by mass to 8000 ppm by mass with respect to the recycled resin composition from a viewpoint of improving a hue.

Examples of the neutralizing agent include calcium stearate, hydrotalcite, an oxide of an alkaline earth metal, and a hydroxide of an alkaline earth metal. The neutralizing agent is preferably calcium stearate. Note that the neutralizing agent may be used singly or in combination of two or more types thereof.

The content of the neutralizing agent is preferably 100 ppm by mass to 2000 ppm by mass, and more preferably 100 ppm by mass to 500 ppm by mass with respect to the recycled resin composition from a viewpoint of improving an appearance.

In the laminated film according to the present embodiment, the at least one inner layer may contain an unused resin described later. The content of the unused resin is preferably 50% by mass or less, and more preferably 25% by mass or less with respect to one inner layer.

[Surface Layer]

In the laminated film according to the present embodiment, the two surface layers contain an unused resin. The surface layer may contain, as an additive, an antioxidant, an antistatic agent, a neutralizing agent, a weathering agent, a lubricant, an anti-blocking agent, an anti-fogging agent, an anti-dripping agent, a pigment, a filler, or the like.

Examples of a resin constituting the unused resin include a resin similar to the resin constituting the recycled resin. The resin constituting the unused resin is preferably a resin containing a polymer containing a monomer unit derived from at least one selected from the group consisting of ethylene, propylene, and an α-olefin having 4 to 12 carbon atoms, and more preferably a resin containing an ethylene homopolymer or an ethylene-based copolymer containing 50% by mass or more of a monomer unit derived from ethylene.

The ethylene-based copolymer preferably contains 90% by mass or more of a monomer unit derived from ethylene.

When the resin constituting the unused resin is a polyethylene-based resin, an ethylene-based polymer contained in the resin can be manufactured by a known polymerization method using a known polymerization catalyst.

Examples of the polymerization catalyst include a homogeneous catalyst system represented by a metallocene catalyst, a Ziegler type catalyst system, and a Ziegler-Natta type catalyst system. Examples of the homogeneous catalyst system include: a catalyst system containing a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane; a catalyst system containing a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with the transition metal compound to form an ionic complex, and an organic aluminum compound; a catalyst system in which a catalyst component such as a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, or an organic aluminum compound is supported on inorganic particles such as silica and clay minerals, and modified; and a prepolymerization catalyst system prepared by prepolymerizing ethylene or an α-olefin in the presence of the above catalyst systems.

High pressure method low density polyethylene (LDPE) can be manufactured using a radical initiator as a polymerization catalyst.

When the resin constituting the unused resin is a polypropylene-based resin, a propylene-based polymer contained in the resin can be manufactured by a known polymerization method using a known olefin polymerization catalyst.

Examples of the polymerization catalyst include: a Ziegler type catalyst system; a Ziegler-Natta type catalyst system; a catalyst system containing a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane; a catalyst system containing a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with the transition metal compound to form an ionic complex, and an organic aluminum compound; and a catalyst system in which a catalyst component such as a transition metal compound of group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, or an organic aluminum compound is supported on inorganic particles such as silica and clay minerals, and modified, and a prepolymerization catalyst system prepared by prepolymerizing ethylene or an α-olefin in the presence of the above catalyst systems may be used.

The propylene-based polymer may be manufactured by a method in which a plurality of polymerization steps is performed in multiple stages (multistage polymerization method) from a viewpoint of improving productivity. A multistage polymer obtained by such a multistage polymerization method may contain at least two propylene-based polymers, or may contain one propylene-based polymer.

When the resin constituting the unused resin is a poly α-olefin-based resin, an α-olefin-based polymer contained in the resin can be manufactured, for example, using a metallocene catalyst. The metallocene catalyst is, for example, an olefin polymerization catalyst using a transition metal compound having a group having a cyclopentadiene type anion skeleton (hereinafter, also referred to as “metallocene-based transition metal compound”).

The metallocene-based transition metal compound is, for example, a compound represented by formula MLaXn-a (in which M represents a transition metal atom of group 4 of the periodic table of elements or the lanthanide series. L represents a group having a cyclopentadiene type anion skeleton or a group containing a hetero atom, and at least one of Ls is a group having a cyclopentadiene type anion skeleton. The plurality of Ls may be crosslinked with each other. X represents a halogen atom, a hydrogen atom, or a hydrocarbon group having 1 to 20 carbon atoms. n represents a valence of the transition metal atom, and a represents an integer satisfying 0<a≤n).

Examples of the metallocene-based transition metal compound represented by the above formula include bis(1,3-n-butylmethylcyclopentadienyl) zirconium dichloride, bis(1,3-n-propylmethylcyclopentadienyl) zirconium dichloride, bis(n-butylcyclopentadienyl) zirconium dichloride, bis(1,3-dimethylcyclopentadienyl) zirconium dichloride, bis(1,3-diethylcyclopentadienyl) zirconium dichloride, ethylene bis(indenyl) zirconium dichloride, ethylene bis(4-methyl-1-indenyl) zirconium dichloride, and ethylene bis(4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride.

The metallocene-based transition metal compound is preferably used in contact with an activation co-catalyst. Examples of the activation co-catalyst include an activation co-catalyst obtained by using an alumoxane compound or an organoaluminum compound in combination with a boron compound such as tritylborate or anilinium borate. In addition, combined use with a particulate carrier containing an inorganic carrier such as SiO₂or Al₂O₃or an organic carrier such as a polymer of ethylene, styrene, or the like may be performed.

When the resin constituting the unused resin is an acrylic resin, an acrylic polymer contained in the resin can be obtained by polymerizing an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms with, as necessary, a vinyl monomer copolymerizable with the alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms by a method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization.

When the resin constituting the unused resin is a polycarbonate-based resin, a polymer containing a monomer unit derived from a dihydroxy compound contained in the resin can be manufactured by a method for causing a dihydroxy compound such as a dihydric phenol or isosorbide to react with a carbonylating agent by an interfacial polycondensation method, a melt transesterification method, or the like, a method for polymerizing a carbonate prepolymer by a solid phase transesterification method or the like, or polymerizing a cyclic carbonate compound by a ring-opening polymerization method or the like.

In the laminated film according to the present embodiment, the two surface layers may contain the above-described recycled resin. The content of the recycled resin is preferably 50% by mass or less, and more preferably 25% by mass or less with respect to one surface layer.

The thickness of the laminated film according to the present embodiment is preferably 10 μm to 300 μm, and more preferably 100 μm to 150 μm. In the laminated film according to the present embodiment, the thickness of one inner layer is preferably 30 μm to 50 μm, and the thickness of one surface layer is preferably 30 μm to 50 μm.

The laminated film according to the present embodiment can be manufactured using a known method. Examples of the known method include an inflation method and a T-die method, and the inflation method is preferable.

Examples of a method for laminating the layers include: a method using a feed block type die in which a molten resin of a recycled resin or an unused resin flowing into the die from a plurality of extruders is combined in layers in the die; and a method using a multi-manifold type die in which a molten resin of a recycled resin or an unused resin flowing into the die from a plurality of extruders is fed into separate manifolds and combined in layers immediately before a lip portion of the die.

The laminated film can be suitably used as, for example, a packaging bag for storing foods, fibers, miscellaneous goods, and the like, and a packaging container.

2. Bag

A bag according to the present embodiment contains the above-described laminated film.

The bag is manufactured by a known molding method, for example, a method for heat-sealing a tubular film molded by an inflation molding method in a direction (TD direction) orthogonal to a take-up direction (MD direction), a method for stacking two films molded by a T-die cast film molding method and sealing four sides, or the like.

Note that the laminated film and the bag according to the present embodiment are not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. In addition, the configurations, methods, and the like of embodiments other than the above may be arbitrarily adopted and combined, and the configuration, method, and the like according to the above one embodiment may be applied to the configurations, methods, and the like according to embodiments other than the above.

EXAMPLES

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In Examples and Comparative Examples, the following were used.

[Unused Resin Pellet]

An unused resin pellet was prepared by pellet-blending the following (1) to (3) at a mass ratio of 68/29/3.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³) and an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³) and an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass)
- (3) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
  
  [Recycled Resin Pellet]
  
  (Recycled Resin Pellet A)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (4) at a mass ratio of 70/30/3/3.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
- (4) A masterbatch containing an antistatic agent (base resin density=927 kg/m³, antistatic agent component 10% by mass)
  
  (Recycled Resin Pellet B)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (4) at a mass ratio of 87/13/3/3.

- (1) A pellet containing linear low density polyethylene (MFR=2.0 g/10 min, density=913 kg/m³)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
- (4) A masterbatch containing an antistatic agent (base resin density=927 kg/m³, antistatic agent component 10% by mass)
  
  (Recycled Resin Pellet C)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (5) at a mass ratio of 70/30/6.5/3/3.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) An antioxidant masterbatch containing 22000 ppm by mass of an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd.)
- (4) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
- (5) A masterbatch containing an antistatic agent (base resin density=927 kg/m³, antistatic agent component 10% by mass)
  
  (Recycled Resin Pellet D)

A recycled resin pellet was prepared by changing (1) to (5) in the recycled resin pellet-C to a mass ratio of 87/13/8/3/3.

(Recycled Resin Pellet E)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (5) at a mass ratio of 70/30/8/3/3.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) An antioxidant masterbatch containing 22000 ppm by mass of an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd.)
- (4) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
- (5) A masterbatch containing an antistatic agent (base resin density=927 kg/m³, antistatic agent component 10% by mass)
  
  (Recycled Resin Pellet F)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (3) at a mass ratio of 70/30/3.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
  
  (Recycled Resin Pellet G)

A recycled resin pellet was prepared from a raw material film containing the following (1) to (4) at a mass ratio of 70/30/3/12.

- (1) A pellet containing linear low density polyethylene (MFR=1.5 g/10 min, density=923 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (2) A pellet containing linear low density polyethylene (MFR=0.9 g/10 min, density=914 kg/m³), an antioxidant (Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd., 850 ppm by mass), and a neutralizing agent (calcium stearate, 213 ppm)
- (3) A masterbatch containing a white pigment (“SPEM-7A1155” manufactured by Sumika Color Co., Ltd.)
- (4) A masterbatch containing an antistatic agent (base resin density=927 kg/m³, antistatic agent component 10% by mass)
  
  [Measurement Method]

Measured values of items in Examples and Comparative Examples were measured by the following methods.

Using a color computer SM-P45 manufactured by Suga Test Instruments Co., Ltd., an x value (red color mixing ratio), a y value (green color mixing ratio), and a z value (blue color mixing ratio) of a surface layer 1 of a three-layer film prepared in Examples or Comparative Examples were determined on the basis of the stimulus value direct reading method defined in JIS 28722. As a geometric condition of illumination and light reception, the condition a described in “Method for measuring reflective object” was used. The measurement was performed three times for each sample, and a standard deviation of each of the x value, the y value, and the z value was determined. The smaller the standard deviation is, the less a variation in color of the surface layer 1 of the three-layer film is, which is preferable.

Using a color computer SM-P45 manufactured by Suga Test Instruments Co., Ltd., yellowness (YI) of the surface layer 1 of the three-layer film prepared in Examples and Comparative Examples was determined according to the reflection method described in JIS K 7103-1977. The measurement was performed three times for each sample, and an average value thereof was determined. The smaller the yellowness (YI) value, the less yellowing of the film is, which is preferable.

Using a friction coefficient measuring machine AB-401 manufactured by TESTER SANGYO CO., LTD., the following observation film and a surface layer 2 of the three-layer film prepared in Examples or Comparative Examples were rubbed with each other to prepare a sample for a scratch resistance test.

The observation film was slid on the surface layer 2 of the three-layer film according to the procedure of JIS K7125-1987 except that a sliding plate to which the observation film was fixed was moved under a condition of a thread having a weight of 700 g and a sliding speed of 200 m/min. A surface of the observation film was observed with an optical microscope (AxisPro SS manufactured by Micro Support Co., Ltd.) at a magnification of 1948.3 in a reflection mode. As for an observation region, observation was performed at a total of 16 positions formed by arbitrary four positions in the vertical direction and arbitrary four positions in the horizontal direction from a scratched region. In one observation region, observation region was performed in five visual fields×five visual fields, and images of a total of 25 visual fields were synthesized to form one image. The number of scratches appearing in the obtained image was measured, the number of scratches per unit area was determined using a visual field size of the image, and an average in the entire observation region was determined.

(Observation Film Used for Scratch Resistance Test)

A film containing an ethylene-1-hexene copolymer (“Excellen GMH CB0004” manufactured by Sumitomo Chemical Co., Ltd., MFR=0.4 g/10 min, density=926 kg/m³) and having a thickness of 100 μm.

Example 1

A laminated film in which a surface layer 1, an inner layer, and a surface layer 2 were laminated in this order was prepared by a coextrusion inflation molding method. The above-described unused resin pellet was used as each of a resin pellet for the surface layer 1 and a resin pellet for the surface layer 2. The above-described recycled resin pellet was used as a resin pellet for the inner layer.

In coextrusion inflation molding, by performing processing at a die temperature of 200° C., a total extrusion amount of 30 kg/h, a blow ratio of 2.0, and a take-up speed of 4.4 m/min using a three-layer inflation film processing machine manufactured by placo co., ltd., a laminated film having a thickness of surface layer 1/inner layer/surface layer 2 of 40 μm/40 μm/40 μm was prepared. The obtained laminated film was subjected to color tone evaluation and a scratch resistance test. Results thereof are illustrated in Table 1.

Comparative Example 1

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the inner layer, and the above-described recycled resin pellet A was used as the resin pellet for the surface layer 2. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are illustrated in Table 1.

Comparative Example 2

A multilayer film was prepared in a similar manner to Example 1 except that the above-described recycled resin pellet A was used as the resin pellet for the surface layer 1, and the above-described unused resin pellet was used as each of the resin pellet for the inner layer and the resin pellet for the surface layer 2. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are illustrated in Table 1.

Comparative Example 3

A multilayer film was prepared in a similar manner to Example 1 except that the above-described recycled resin pellet A was used as each of the resin pellet for the surface layer 1, the resin pellet for the inner layer, and the resin pellet for the surface layer 2. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are illustrated in Table 1.

Reference Example 1

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1, the resin pellet for the inner layer, and the resin pellet for the surface layer 2. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are illustrated in Table 1.

Example 2

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet B was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

Example 3

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet F was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

Example 4

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet G was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

Comparative Example 4

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet C was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

Comparative Example 5

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet D was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

Comparative Example 6

A multilayer film was prepared in a similar manner to Example 1 except that the above-described unused resin pellet was used as each of the resin pellet for the surface layer 1 and the resin pellet for the surface layer 2, and the above-described recycled resin pellet E was used as the resin pellet for the inner layer. The obtained multilayer film was subjected to color tone evaluation and a scratch resistance test. Results thereof are presented in Table 2.

TABLE 1

Comparative
Comparative
Comparative
Reference

Example 1
Example 1
Example 2
Example 3
Example 1