Stretch film

Abstract

To provide a stretch film which prevents breakage when being packaged at 10°C and 35°C.SOLUTION: A stretch film contains a polyvinyl chloride-based resin, an adipic acid-based plasticizer, a vegetable plasticizer, and an antifogging agent, wherein the content of the adipic acid-based plasticizer is 20 to 40 pts.mass with respect to 100 pts.mass of the polyvinyl chloride-based resin, the content of the vegetable plasticizer is 16 to 20 pts.mass with respect to 100 pts.mass of the polyvinyl chloride-based resin, and the content of the antifogging agent is 1 to 5 pts.mass of 100 pts.mass of the polyvinyl chloride-based resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to stretch film. [Background technology]

[0002] Traditionally, stretch film, which offers excellent flexibility, has been widely used for packaging fresh foods such as meat, fish, and produce. Specifically, stretch film is used for pre-packaging, where fresh foods are placed in a polystyrene foam container and the stretch film is overlapped over the container to package the fresh foods. Stretch film is a film made of resin such as polyvinyl chloride resin, and for example, the one described in Patent Document 1 is known. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-104241 [Overview of the project] [Problems that the invention aims to solve]

[0004] Fresh foods are usually packaged at room temperature (20-25°C), but sometimes packaging is done in relatively high-temperature environments such as 35°C or relatively low-temperature environments such as 10°C. The inventors have investigated this and found that even stretch films that can be used for packaging without tearing at room temperature may tear during packaging if the temperature is only about 10°C higher or lower than room temperature. Therefore, stretch films need to be able to be used for packaging without tearing even with such slight temperature changes.

[0005] Therefore, the present invention aims to provide a stretch film that is less prone to tearing during packaging at 10°C and 35°C. [Means for solving the problem]

[0006] One aspect of the present invention includes the following [1] to [9]. [1] Contains polyvinyl chloride resin, adipic acid plasticizer, plant-derived plasticizer, and anti-fogging agent, The content of the adipic acid-based plasticizer is 20 to 40 parts by mass per 100 parts by mass of the polyvinyl chloride resin. The content of the aforementioned plant-derived plasticizer is 16 to 20 parts by mass per 100 parts by mass of the polyvinyl chloride resin. A stretch film in which the anti-fogging agent is contained in an amount of 1 to 5 parts by mass per 100 parts by mass of the polyvinyl chloride resin. [2] The stretch film according to [1], wherein the plant-based plasticizer is epoxidized soybean oil. [3] The stretch film according to [1] or [2], wherein the adipic acid-based plasticizer is diisononyl adipate. [4] The stretch film according to any one of [1] to [3], wherein the ratio of the mass-based content of the plant-derived plasticizer to the mass-based content of the adipic acid-based plasticizer is 0.45 to 0.9. [5] The stretch film according to any one of [1] to [4], wherein the anti-fogging agent is a glycerin-based surfactant. [6] A stretch film according to any one of [1] to [5], further containing a stabilizer. [7] A stretch film according to any one of [1] to [6], having a thickness of 8 to 15 μm. [8] Storage modulus at 10°C and 35°C is 5 × 10 7 ~3×10 8 A stretch film according to any one of [1] to [7], wherein the film impact strength at 10°C and 35°C is 10 to 40 kJ / m, and the film impact strength is 10 to 40 kJ / m. [9] A stretch film used for food packaging, as described in any one of [1] to [8]. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a stretch film that is less prone to tearing during packaging at 10°C and 35°C. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below.

[0009] A stretch film according to one embodiment contains a polyvinyl chloride resin, an adipic acid plasticizer, a plant-derived plasticizer, and an antifogging agent. In the stretch film, the content of the adipic acid plasticizer is 20 to 40 parts by mass per 100 parts by mass of the polyvinyl chloride resin, the content of the plant-derived plasticizer is 16 to 20 parts by mass per 100 parts by mass of the polyvinyl chloride resin, and the content of the antifogging agent is 1 to 5 parts by mass per 100 parts by mass of the polyvinyl chloride resin.

[0010] (Polyvinyl chloride resin) The stretch film contains a polyvinyl chloride resin. The polyvinyl chloride resin may be a polyvinyl chloride homopolymer (polyvinyl chloride), or a copolymer of polyvinyl chloride and other monomers copolymerizable with polyvinyl chloride. The copolymer may be a graft copolymer, a block copolymer, or a random copolymer. Examples of other monomers include olefins such as ethylene, propylene, and polybutene; vinyl esters of saturated acids such as vinyl acetate and vinyl laurate; alkyl esters of unsaturated acids such as methyl acrylate and methyl methacrylate; alkyl vinyl ethers such as lauryl vinyl ether; maleic acid, acrylonitrile, styrene, methylstyrene, and vinylidene fluoride.

[0011] The degree of polymerization of the polyvinyl chloride resin may be 700-1700, 1000-1500, or 1200-1400, from the viewpoint of providing superior stretch film strength and making the stretch film more tear-resistant.

[0012] When the polyvinyl chloride-based resin is a copolymer, the content of vinyl chloride units in the copolymer may be 10 mass% or more, 30 mass% or more, or 50 mass% or more, based on the total amount of all monomer units. The upper limit of the content of vinyl chloride units in the copolymer is not particularly limited, and for example, may be 100 mass% or less, or 95 mass% or less, based on the total amount of all monomer units.

[0013] The content of the polyvinyl chloride-based resin, from the viewpoint of further improving the strength of the stretch film and making the stretch film more resistant to tearing, may be 50 mass% or more or 60 mass% or more based on the total amount of the stretch film; and from the viewpoint of suppressing the stretch film from becoming too hard by improving the stretchability of the stretch film and further suppressing deformation of the container during pre-packaging, may be 80 mass% or less or 70 mass% or less.

[0014] (Adipic acid-based plasticizer) The stretch film contains an adipic acid-based plasticizer. The adipic acid-based plasticizer is an adipic acid ester. The content of the adipic acid-based plasticizer in the stretch film is 20 to 40 parts by mass relative to 100 parts by mass of the polyvinyl chloride-based resin.

[0015] Examples of the adipic acid-based plasticizer include bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis(2-butoxyethyl) adipate, and the like. The stretch film may contain one type of adipic acid-based plasticizer, or may contain two or more types of adipic acid-based plasticizers.

[0016] The content of the adipic acid-based plasticizer may be 10 mass% or more, 12 mass% or more, or 14 mass% or more based on the total amount of the stretch film, from the viewpoint of suppressing the storage modulus at 10°C from becoming too high, further improving the strength of the stretch film at 10°C, and making the stretch film more resistant to breaking, and may be 34 mass% or less, 32 mass% or less, or 30 mass% or less from the viewpoint of increasing the storage modulus at 35°C, further improving the strength of the stretch film at 35°C, and making the stretch film more resistant to breaking.

[0017] The content of the adipic acid-based plasticizer may be 25 parts by mass or more, 28 parts by mass or more, or 30 parts by mass or more relative to 100 parts by mass of the polyvinyl chloride-based resin, from the viewpoint of suppressing the storage modulus at 10°C from becoming too high, further improving the strength of the stretch film at 10°C, and making the stretch film more resistant to breaking, and may be 35 parts by mass or less, 32 parts by mass or less, or 30 parts by mass or less from the viewpoint of making the storage modulus at 35°C sufficiently high, further improving the strength of the stretch film at 35°C, and making the stretch film more resistant to breaking.

[0018] (Vegetable-derived plasticizer) The stretch film contains a vegetable-derived plasticizer. The vegetable-derived plasticizer is a plasticizer produced from plant-derived raw materials. The content of the vegetable-derived plasticizer in the stretch film is 16 to 20 parts by mass relative to 100 parts by mass of the polyvinyl chloride-based resin.

[0019] Examples of the vegetable-derived plasticizer include epoxidized vegetable oils, cardanol, isosorbide esters, citrates and the like. These may be derived from vegetable raw materials such as soybean, palm, castor oil, citrate, stearic acid, starch and the like. The vegetable-derived plasticizer may be an epoxidized vegetable oil from the viewpoint of excellent miscibility with other components. The stretch film may contain one type of vegetable-derived plasticizer, or may contain two or more types of vegetable-derived plasticizers.

[0020] Examples of epoxidized vegetable oils include epoxidized soybean oil (ESBO), epoxidized linseed oil, and epoxidized safflower oil. The vegetable plasticizer may also be epoxidized soybean oil, due to its excellent miscibility with other components.

[0021] The amount of plant-derived plasticizer may be 8% by mass or more, 9% by mass or more, or 10% by mass or more, based on the total amount of stretch film, from the viewpoint of ensuring that the storage modulus at 35°C is sufficiently large, the strength of the stretch film at 35°C is superior, and the stretch film is more tear-resistant. Alternatively, from the viewpoint of preventing the storage modulus at 10°C from becoming excessively large, the strength of the stretch film at 10°C is superior, and the stretch film is more tear-resistant, the amount may be 16% by mass or less, 15% by mass or less, or 14% by mass or less.

[0022] The amount of plant-derived plasticizer may be 17 parts by mass or more, or 18 parts by mass or more, per 100 parts by mass of polyvinyl chloride resin, from the viewpoint of ensuring that the storage modulus at 35°C is sufficiently high, the strength of the stretch film at 35°C is superior, and the stretch film is more tear-resistant. Alternatively, from the viewpoint of preventing the storage modulus at 10°C from becoming excessively high, the strength of the stretch film at 10°C is superior, and the stretch film is more tear-resistant, the amount may be 20 parts by mass or less, or 19 parts by mass or less.

[0023] The ratio of the mass-based content of plant-derived plasticizer to the mass-based content of adipic acid-based plasticizer may be 0.45 or higher, 0.5 or higher, 0.55 or higher, or 0.6 or higher, from the viewpoint of ensuring that the storage modulus at 35°C is sufficiently large, the strength of the stretch film at 35°C is superior, and the stretch film is more tear-resistant. From the viewpoint of preventing the storage modulus at 10°C from becoming excessively large, the strength of the stretch film at 10°C is superior, and the stretch film is more tear-resistant, the ratio may be 0.9 or lower, 0.85 or lower, 0.8 or lower, 0.75 or lower, 0.7 or lower, 0.65 or lower, or 0.6 or lower. From these viewpoints, the ratio may be between 0.45 and 0.9.

[0024] (Anti-fogging agent) The stretch film contains an anti-fogging agent. The anti-fogging agent may be a surfactant. The amount of anti-fogging agent in the stretch film is 1 to 5 parts by mass per 100 parts by mass of polyvinyl chloride resin.

[0025] Examples of antifogging agents include glycerin-based surfactants. Glycerin-based surfactants are surfactants in which a fatty acid is ester-bonded to the hydroxyl group of glycerin. Examples of glycerin-based surfactants include monoglycerin-based surfactants, diglycerin-based surfactants, and polyglycerin-based surfactants. The stretch film may contain one type of antifogging agent, or it may contain two or more types of antifogging agents from the viewpoint of improving the antifogging properties of the stretch film and suppressing the clouding of the stretch film.

[0026] Examples of monoglycerin-based surfactants include monoglycerin laurate, monoglycerin myristate, monoglycerin palmitate, monoglycerin stearate, monoglycerin oleate, and monoglycerin linoleate. From the viewpoint of improving the anti-fogging properties of the stretch film and suppressing the clouding of the stretch film, monoglycerin-based surfactant may also be monoglycerin stearate.

[0027] Examples of diglycerin-based surfactants include diglycerin laurate, diglycerin myristate, diglycerin palmitate, diglycerin stearate, diglycerin oleate, and diglycerin linoleate. Diglycerin oleate may also be used as the diglycerin-based surfactant from the viewpoint of improving the anti-fogging properties of the stretch film and suppressing the clouding of the stretch film.

[0028] The stretch film may contain a monoglycerin-based surfactant and a diglycerin-based surfactant as anti-fogging agents, from the viewpoint of improving the anti-fogging properties of the stretch film and suppressing the clouding of the stretch film. When the stretch film contains a monoglycerin-based surfactant and a diglycerin-based surfactant, the mass-based content of the diglycerin-based surfactant relative to the mass-based content of the monoglycerin-based surfactant may be 1 or more, 1.5 or more, 2 or more, 3 or more, or 4 or more, and may be 10 or less, 8 or less, 6 or less, 5 or less, or 4 or less.

[0029] The amount of anti-fogging agent may be 0.5% by mass or more, 1% by mass or more, or 1.5% by mass or more, based on the total amount of stretch film, from the viewpoint of making it easier for the stretch film to peel off from the dispensing device when the stretch film is unwound and from the viewpoint of suppressing fogging on the stretch film after packaging. Alternatively, it may be 5% by mass or less, 3.5% by mass or less, or 3% by mass or less, from the viewpoint of making it less likely for wrinkles to occur in the stretch film when the stretch film is unwound.

[0030] The amount of anti-fogging agent may be 1.5 parts by mass or more, 2 parts by mass or more, or 2.5 parts by mass or more per 100 parts by mass of polyvinyl chloride resin, from the viewpoint of making it easier for the stretch film to peel off from the dispensing device when the stretch film is unwound and from the viewpoint of suppressing fogging on the stretch film after packaging. Alternatively, it may be 4.5 parts by mass or less, 4 parts by mass or less, or 3.5 parts by mass or less, from the viewpoint of making it less likely for wrinkles to occur in the stretch film when the stretch film is unwound.

[0031] The ratio of the mass-based content of the anti-fogging agent to the mass-based content of the adipic acid-based plasticizer may be 0.03 or higher, 0.05 or higher, 0.08 or higher, or 0.1 or higher, from the viewpoint of making it easier for the stretch film to peel off the dispensing device when the stretch film is unwound, and from the viewpoint of suppressing fogging on the stretch film after packaging. The ratio may also be 0.2 or lower, 0.17 or lower, 0.15 or lower, 0.13 or lower, 0.11 or lower, or 0.1 or lower, from the viewpoint of making it less likely for wrinkles to occur in the stretch film when the stretch film is unwound.

[0032] The ratio of the mass-based content of the anti-fogging agent to the mass-based content of the plant-derived plasticizer may be 0.05 or higher, 0.08 or higher, 0.1 or higher, 0.15 or higher, or 0.17 or higher, from the viewpoint of making it easier for the stretch film to peel off the dispensing device when the stretch film is unwound, and from the viewpoint of suppressing fogging on the stretch film after packaging. The ratio may also be 0.3 or lower, 0.28 or lower, 0.25 or lower, 0.22 or lower, 0.2 or lower, or 0.17 or lower, from the viewpoint of making it less likely for wrinkles to occur in the stretch film when the stretch film is unwound.

[0033] The stretch film may contain other components in addition to the components listed above. Examples of other components include resins other than polyvinyl chloride resins, stabilizers, lubricants, fillers, plate-out prevention agents, antioxidants, release agents, viscosity reducers, colorants, fluorescent agents, surface treatment agents, crosslinking agents, processing aids, adhesives, antistatic agents, UV absorbers, antiblocking agents, etc.

[0034] Examples of stabilizers include calcium salts such as 2-ethylhexyl acid, citric acid, gluconic acid, sorbic acid, benzoic acid, isodecanoic acid, and neodecanoic acid; zinc salts such as 2-ethylhexyl acid, higher fatty acids, isodecanoic acid, and neodecanoic acid; and Ca-Zn salts such as 2-ethylhexyl acid, higher fatty acids, isodecanoic acid, and neodecanoic acid (e.g., Ca-Zn higher fatty acids). The stretch film may contain one type of stabilizer or two or more types of stabilizers.

[0035] When stretch film contains a phosphorus compound as a stabilizer, from the viewpoint of suppressing discoloration of food when the stretch film is used for food packaging, the amount of the phosphorus compound may be 2% by mass or less, and preferably 1% by mass or less, based on the total amount of stretch film. Examples of phosphorus compounds include trisnonylphenyl phosphite, triphenyl phosphite, diphenyldecyl phosphite, tridecyl phosphite, tris(2-ethylhexyl) phosphite, tristearyl phosphite, 4,4-butylidene(3-methyl6-t-butylphenylditridecyl) phosphite, octyldiphenyl phosphite, and the like.

[0036] The content of biomass-derived materials in stretch film may be 8% or more by mass, 9% or more by mass, or 10% or more by mass, from the viewpoint of reducing carbon dioxide emissions. Examples of biomass-derived materials include the plant-based plasticizers mentioned above.

[0037] The thickness of the stretch film may be 8 μm or more, 9 μm or more, 10 μm or more, or 11 μm or more, from the viewpoint of providing superior strength and resistance to tearing. The thickness of the stretch film may be 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, or 11 μm or less, from the viewpoint of further suppressing deformation of the container during pre-packaging. From these viewpoints, the thickness of the stretch film may be 8 to 15 μm.

[0038] The storage modulus of stretch film at 10°C and 35°C is set to 3 × 10 8 It may be less than Pa, and from the viewpoint of having better stretch film strength and making the stretch film more tear-resistant, 5×10 7 The above may also be acceptable. From these perspectives, the storage modulus of stretch film at 10-35°C is 5 × 107 ~3×10 8 Pa is preferred.

[0039] The storage elastic modulus of the stretch film at 10°C is, from the viewpoint of suppressing the stretch film from becoming too hard at 10°C and easily suppressing deformation of the container during pre-packaging, 3×10 8 Pa or lower, and from the viewpoint of further improving the strength of the stretch film at 10°C and making the stretch film more resistant to tearing, it may be 2×10 8 or higher. From these viewpoints, the storage elastic modulus of the stretch film at 10°C is preferably 2×10 8 ~3×10 8 Pa.

[0040] The storage elastic modulus of the stretch film at 35°C is, from the viewpoint of suppressing the stretch film from becoming too hard at 35°C and making the stretch film more resistant to tearing, 6×10 7 Pa or lower, and from the viewpoint of suppressing the stretch film from stretching excessively at 35°C and making the stretch film more resistant to tearing, it may be 4×10 7 or higher. From these viewpoints, the storage elastic modulus of the stretch film at 35°C is preferably 4×10 7 ~6×10 7 Pa.

[0041] The film impact strength at 10°C and 35°C may be 10 kJ / m or higher, 12 kJ / m or higher, or 14 kJ / m or higher from the viewpoint of making the stretch film more resistant to tearing, and from the viewpoint of suppressing the stretch film from becoming too hard and further suppressing deformation of the container during pre-packaging, it may be 40 kJ / m or lower, 38 kJ / m or lower, 36 / m or lower, 34 / m or lower, or 32 / m or lower. From these viewpoints, the film impact strength at 10°C and 35°C may be 10 to 40 kJ / m.

[0042] The film impact strength at 10°C may be 30 kJ / m or more, 32 kJ / m or more, or 34 kJ / m or more, from the viewpoint of making the stretch film more tear-resistant at 10°C, or it may be 40 kJ / m or less, 38 kJ / m or less, or 36 kJ / m or less, from the viewpoint of suppressing the stretch film from becoming too hard at 10°C and further suppressing the deformation of the container during pre-packaging. From these viewpoints, the film impact strength at 10°C is preferably 30 to 40 kJ / m.

[0043] The film impact strength at 35°C may be 10kJ / m or more, 12kJ / m or more, or 14kJ / m or more, from the viewpoint of making the stretch film more tear-resistant at 35°C, or it may be 20kJ / m or less, 18kJ / m or less, or 16kJ / m or less, from the viewpoint of suppressing the stretch film from becoming too hard at 35°C and further suppressing the deformation of the container during pre-packaging. From these viewpoints, the film impact strength at 35°C is preferably 10 to 20kJ / m.

[0044] Stretch film may be used for food packaging, or for pre-packaging food. Furthermore, stretch film may be used for packaging non-food items (e.g., pharmaceuticals). [Examples]

[0045] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0046] (Examples 1-9, Comparative Examples 1-6) The amounts (in parts by mass) of polyvinyl chloride resin (PVC, Taiyo Vinyl Chloride Co., Ltd. TH-1300, degree of polymerization: 1300), diisononyl adipate (DINA), epoxidized soybean oil (ESBO), glycerin-based surfactant (Riken Vitamin Co., Ltd.), and Ca-Zn higher fatty acid salts (ADEKA Corporation) shown in Tables 1 and 2 were kneaded in a Henschel mixer. Then, using a single-screw extruder (Toshiba Machine Co., Ltd., screw diameter: 65 mm, effective screw length L / D: 28), a T-die with a die width of 550 mm and a die lip of 0.7 mm was used, and the extrusion was carried out at a set temperature of 170-200°C and a take-up speed of 50 m / min to obtain a stretch film with a thickness of 11 μm and a width of 300 mm.

[0047] <Measurement of Storage Modulus> The storage modulus at 10°C and 35°C was measured using a dynamic viscoelasticity analyzer (TA Instruments, product name: RSA-G2). The main measurement parameters involved are as follows. The measurement results are shown in Tables 1 and 2. Heating rate: 5°C / min Measurement frequency 1Hz

[0048] <Measurement of film impact strength> The film impact strength at 10°C and 35°C was measured using a film impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.). A Φ1 / 2 inch impact sphere was used. The measurement results are shown in Tables 1 and 2.

[0049] <Evaluation of appearance> At 10°C and 35°C, expanded polystyrene containers manufactured by Denka Polymer Co., Ltd., measuring 25cm wide x 18cm deep x 3.3cm high, were wrapped in stretch film using an automatic packaging machine (manufactured by Ishida Co., Ltd., product name: WM-AI Super), and their appearance was evaluated based on the following evaluation criteria. The evaluation results are shown in Tables 1 and 2. A: There were no tears in the stretch film. B: There was a tear in the stretch film. C: The stretch film could not be dispensed.

[0050] Table 1

[0051] Table 2

Claims

1. It contains a polyvinyl chloride homopolymer resin, an adipic acid-based plasticizer, a plant-derived plasticizer, and an anti-fogging agent. The content of the adipic acid-based plasticizer is 20 to 40 parts by mass per 100 parts by mass of the polyvinyl chloride resin. The content of the aforementioned plant-derived plasticizer is 16 to 20 parts by mass per 100 parts by mass of the polyvinyl chloride resin. The aforementioned anti-fogging agent is a glycerin-based surfactant. The glycerin-based surfactant includes a monoglycerin-based surfactant. A stretch film in which the anti-fogging agent is contained in an amount of 2 to 5 parts by mass per 100 parts by mass of the polyvinyl chloride resin.

2. The stretch film according to claim 1, wherein the plant-based plasticizer is epoxidized soybean oil.

3. The stretch film according to claim 1 or 2, wherein the adipic acid-based plasticizer is diisononyl adipate.

4. The stretch film according to claim 1 or 2, wherein the ratio of the mass-based content of the plant-derived plasticizer to the mass-based content of the adipic acid-based plasticizer is 0.45 to 0.

9.

5. The stretch film according to claim 1 or 2, further containing a stabilizer.

6. A stretch film according to claim 1 or 2, having a thickness of 8 to 15 μm.

7. The storage modulus at 10°C and 35°C is 5 × 10⁻⁶. ７ ~3 x 10 ８ The stretch film according to claim 1 or 2, wherein the film is Pa and has a film impact strength of 10 to 40 kJ / m at 10°C and 35°C.

8. A stretch film according to claim 1 or 2, used for packaging food products.

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