JP2018131228A - Packaging film - Google Patents

Abstract

An object of the present invention is to provide a packaging film which is a thick and thick material, has improved straight cut performance when opened and cut by hand, and has an excellent appearance after shrink wrapping.
The packaging film of the present invention is a packaging film made of a biaxially stretched film mainly containing a styrene resin composition, wherein the packaging film has a thickness (t: unit μm), and JIS. The tear strength (R: unit mN) measured in accordance with P8116 satisfies the relationship of the following formulas (1) and (2).
30 ≦ t ≦ 80 (1)
1 ≦ R / t <1.7 (2)
[Selection figure] None

Description

  The present invention relates to a packaging film. In addition, the present invention relates to a packaging, a banding, a tape, or a label for packaging used for containers in which food or the like is packaged, collective packaging of printed matter, books, stationery, and the like, and a package using these.

  Conventionally, in packaged containers such as bento boxes and side dishes sold in stores such as supermarkets and convenience stores, food is stored in the container body, and then covered with a lid, so that it does not open in a delusion. For this reason, “stapling” and “stretch film fixing” were performed. However, recently, because of the ease of separation and disposal, it has been “banded or band-sealed” or “taped or labeled” as a packaging film that does not use staple metal and consumes a small amount of film. It has increased.

  As banding or banding applied to containers packed with food, etc., when opening the band, the upper half of the band located on the upper side of the container so that the band can be easily cut by hand Made of unstretched film such as polystyrene (PS) or polyethylene terephthalate (PET) or paper material, and the lower half located on the bottom side of the container can be heat-shrinkable along the band direction, such as PS and PET There is known a stretched film formed by joining both halves (band) (see Patent Document 1). In the band seal of Patent Document 1, after wrapping a packaged container, the lower half of the band seal is thermally shrunk using a heating means such as placing on a hot plate or supplying hot air to Can be tightened.

  As banding or banding applied to collective wrapping such as printed matter, books and stationery, banding film made of thick polypropylene (PP) with a thickness of 80 to 250 μm (see Patent Document 2), band paper for banknotes, craft A band paper in which an adhesive layer is formed by laminating polyethylene (PE) on the surface of a paper such as paper as a base is known (see Patent Document 3).

  As a tape or label applied to a container or the like covered with a lid, an adhesive tape made of a PET film or PP film and having a specific elastic modulus provided with a cut for cutting by hand is known (patent) Reference 4).

JP 2000-0799970 A JP 2006-082662 A JP 2002-178433 A JP 2012-2111247 A

  However, the band seal described in Patent Document 1 has no description of waist (rigidity) when handled by hand, and unstretched PS film, stretched PET film, etc. have hand cutting ability and straight cut ability. It was not enough. The band sealing tape described in Patent Document 2 has insufficient straight-cutting properties in the width direction of the band, and may be torn in the length direction of the band, which has a problem in unsealing property and separation property. In the band based on the paper described in Patent Document 3, it is preferably used for bundling banknotes, etc., but when used for a packaging container containing food such as sugar beet covered with a lid, Since there was no shrinkability, there was a problem that the appearance of the shrink wrap was inferior, and the band seal was loose and easily removed. The pressure-sensitive adhesive tape (wrapped film coated with a pressure-sensitive adhesive) made of PET or PP described in Patent Document 4 has insufficient straight cut property, although it has hand cutting properties. In particular, adhesive tape with cuts to cut by hand is cut off when the adhesive tape wound around a paper tube is pulled out with an angle at the cut, and the tape is cut off. There was a problem.

  Therefore, the present invention improves the straight cut performance at the time of manual opening and separation with a thick thick material, and further increases the usage ratio of recycled materials from the viewpoint of increased environmental awareness and resource saving, after shrink packaging An object of the present invention is to provide a packaging film, banding, band sealing, tape, label, and a package using these, which are excellent in appearance.

  As a result of intensive studies in order to solve the above problems, the present inventor is a packaging film made of a biaxially stretched film, which mainly includes a styrene-based resin composition, is a thick film having a waist, The inventors have found that the above problems can be solved by setting the tear strength per unit film thickness in at least one direction within a specific range, and the present invention has been completed.

  That is, the present invention is as follows.

[1]
A packaging film comprising a biaxially stretched film mainly containing a styrene-based resin composition, wherein the packaging film has a thickness (t: unit μm) and at least one-way tear strength measured according to JIS P8116 ( R: mN) and the packaging film satisfying the relationship of the following formulas (1) and (2).
30 ≦ t ≦ 80 (1)
1 ≦ R / t <1.7 (2)

[2]
The packaging film according to [1] above, wherein the styrene resin composition contains 40 to 98% by mass of a styrene recycled resin having an MFR of 4 to 7 g / 10 min.

[3]
The packaging film according to [1] or [2], wherein the packaging film has a heat shrinkage in the length direction and the width direction at 110 ° C. of 1 to 15%.

[4]
A banding or banding comprising the packaging film according to any one of the above [1] to [3].

[5]
Heat in the length direction at 110 ° C. including a packaging film having a heat shrinkage rate in the length direction of 1 to 5% at 110 ° C. and a packaging film having a heat shrinkage rate in the length direction of 110 ° C. of 5 to 15% The banding or banding according to [4] above, wherein two or more packaging films having different shrinkage rates are joined.

[6]
A package comprising the banding or sealing according to [4] or [5] above.

[7]
A tape or label, characterized in that an adhesive layer is disposed on at least one surface of the packaging film according to any one of [1] to [3].

[8]
A package, wherein the tape or label according to [7] is attached.

  According to the present invention, it is excellent in straight cut performance at the time of manual opening and separation with a thick material with a waist, and further, the ratio of recycled raw materials is increased from the viewpoint of increased environmental awareness and resource saving, and after shrink wrapping It is possible to provide a packaging film excellent in appearance, a banding, a band seal, a tape, a label, and a package using these.

FIG. 1 is a conceptual diagram showing an embodiment of a package packaged with a banding made of a packaging film of the present embodiment. Drawing 2 is a key map showing one embodiment of a package provided with a tape containing a film for packing of this embodiment.

  Hereinafter, embodiments of the present invention (hereinafter also referred to as “present embodiments”) will be described in detail with reference to the drawings. The packaging film of the present embodiment is a strap for preventing the lid of a container in which food or the like has been packaged from being opened or the collective packaging of printed matter, books, stationery, etc. from collapsing the collective packaging. It may be a bandage, a tape, a label, or the like. In addition, in FIG. 1, 2, the case of the packaging container for foods which covered the cover body is illustrated. In addition, this invention is not limited to the following embodiment.

(Packaging film)
The packaging film of the present embodiment is a packaging film composed of a biaxially stretched film mainly containing a styrene resin composition, and the thickness (t: unit μm) of the packaging film and JIS P8116. The tear strength (R: unit mN) measured in at least one direction satisfies the following formulas (1) and (2).
30 ≦ t ≦ 80 (1)
1 ≦ R / t <1.7 (2)
“Containing styrene resin composition as a main component” means that the content of the styrene resin composition is 50% by mass or more with respect to the total amount of the biaxially stretched film (100% by mass). 75 mass% or more may be sufficient and 100 mass% may be sufficient.

  The packaging film of the present embodiment contains a styrene resin composition as a main component from the viewpoint of film stiffness (rigidity) and hand cutting properties. The packaging film of the present embodiment may contain only a thermoplastic resin as a resin component, and in addition to a styrene resin, it is a transparent thermoplastic resin that can be formed into a film, such as an ethylene resin or propylene. It may contain olefin resins such as polypropylene resins (including polypropylene), ester resins (including polyethylene terephthalate and polylactic acid), amide resins, etc. From the viewpoint of superiority, it is preferable that only the styrene resin is included as the thermoplastic resin.

The styrenic resin composition is one styrenic resin or a mixture of two or more styrenic resins.
Examples of the styrenic resin include homopolymers or copolymers of styrenic monomers.

  Examples of the styrene monomer include styrene, alkyl styrene such as α-methyl styrene (for example, alkyl styrene having 1 to 8 carbon atoms in the alkyl group), and the like. Of these, styrene is desirable from the viewpoint of film stiffness (rigidity) and transparency.

As the homopolymer of the styrene monomer, a styrene homopolymer such as general-purpose polystyrene GPPS is preferable from the viewpoints of film stiffness (rigidity) and transparency.
Homopolymers of styrenic monomers may be used alone or in combination of two or more.

Further, as the copolymer of the styrene monomer, the content of the structural unit derived from the styrene monomer in the copolymer is 50 masses. % (Wt%) or more of a copolymer of a styrene monomer and a monomer other than the styrene monomer.
Examples of the styrene monomer copolymer include a styrene- (meth) acrylic acid copolymer, a styrene- (meth) acrylic acid ester copolymer, a styrene-acid anhydride copolymer, and these three types. One selected from the group consisting of terpolymers comprising an ester component as a further monomer component in addition to two monomer components constituting any one of the above copolymers; styrene-butadiene copolymer; Examples thereof include copolymers such as impact polystyrene (for example, HIPS); styrene-α-methylstyrene copolymer; polymer alloy of polystyrene and polyphenylene ether resin (m-PPE); Among these, from the viewpoint of heat resistance and workability of the film, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid ester copolymer, styrene-acid anhydride copolymer, and these three types One type selected from the group consisting of ternary copolymers containing an ester component as a further monomer component in addition to two types of monomer components constituting any one of these copolymers is desirable.
Copolymers of styrenic monomers may be used alone or in combination of two or more.

The melt mass flow rate (MFR) of the styrene monomer homopolymer and copolymer is preferably 1 to 10 g / 10 min, more preferably 1.5 to 9 g / 10 min. An MFR of 1 g / 10 min or more is preferable because the kneadability with the styrenic regenerated resin is good, there is no need to extrude at a high temperature, the molecular weight decrease of the styrenic regenerated resin is small, and the amount of oligomer components generated is small. When the MFR is 10 g / 10 min or less, the molecular weight of the homopolymer and copolymer of the styrene monomer becomes appropriate, and the film strength is excellent.
In this specification, MFR shall mean the value measured according to JIS K7210.

The styrenic resin may be a recycled resin or may not be a recycled resin. Among these, from the viewpoint of resource saving, it is preferable that the styrene resin composition contains a regenerated resin. In the present specification, a resin that is not a recycled resin may be referred to as a “non-recycled resin”.
The above-mentioned recycled resin of styrenic resin (styrene-based recycled resin) is a film / sheet product after the virgin material has been subjected to at least one thermal history and commercialized as a film / sheet and supplied to the market. Scraps generated during the secondary processing (for example, transparent lids for lunch boxes and side dishes) were separated and collected, and received at least two thermal histories that were pelletized through at least one thermal history. A pre-consumer material that conforms to JIS Q14021 (ISO 14021) and does not include a styrene resin used as a secondary processed product is preferred, and is preferably a recycled resin mainly composed of a general-purpose polystyrene resin. Note that products such as films and sheets using recycled resin can also be determined based on the presence or absence of a certification mark for Eco Mark products.
Above all, since transparency is required for the packaging film, the styrene resin composition is made of the same material styrene resin and styrene recycled resin (for example, made of polystyrene and a recycled resin of polystyrene). , GPPS, HIPS and polystyrene recycled resin, HIPS and polystyrene recycled resin, etc.).

  The MFR of the styrene resin decreases in molecular weight and increases in MFR every time it receives a thermal history. The MFR of the styrene-based recycled resin is preferably 1.5 to 10 g / 10 minutes, more preferably 2 to 8 g / 10 minutes, and still more preferably 4 to 7 g / 10 minutes. A recycled resin of 1.5 g / 10 min or more is stably produced, and is easily available for industrial production. A styrene-based recycled resin of 10 g / 10 min or less has sufficient strength as in the case of a virgin raw material.

The styrenic resin composition may be a mixed composition of a styrenic resin (non-regenerated resin, particularly a resin that has not been subjected to secondary processing and has a thermal history of once or less) and a styrenic regenerated resin. The mixing ratio is preferably determined so that the MFR falls within the range of 2 to 8 g / 10 minutes.
At this time, it is preferable to use a styrene-based recycled resin that is easily available and has an MFR of 4 to 7 g / 10 min from the viewpoint of increasing environmental awareness in recent years and saving resources. Moreover, it is preferable that the usage-amount of a styrene-type reproduction | regeneration resin is 40 mass%-98 mass% with respect to a mixture (100 mass%). The styrene resin (non-regenerated resin) and the styrene recycled resin are preferably the same type of styrene resin.
Here, the mixture refers to a styrene-based resin composition and a mixture containing known additives such as inorganic fine particles, a heat stabilizer, an antioxidant, and an ultraviolet absorber, which are added as necessary. It is good also as a resin composition.

Here, by containing impact-resistant polystyrene (HIPS), inorganic fine particles, and the like, irregularities are formed on the film surface, and there is an effect of preventing blocking between films, but when it is contained in a large amount, Deteriorating is undesirable. In particular, when used for banding or sealing, the mixing ratio of impact-resistant polystyrene, inorganic fine particles, etc. is set so that the haze value of the packaging film does not exceed 30% from the viewpoint of the visibility of the package. It is preferable to do. From the viewpoint of preventing blocking between films, the content of HIPS in the packaging film is preferably 1.5% by mass or more, more preferably 2.0% by mass or more, and 10% by mass or less. It is preferable that
The Haze value can be measured according to JIS K7105.

  The MFR of the styrene resin composition is preferably 2 to 8 g / 10 minutes, more preferably 3 to 6 g / 10 minutes. When the MFR of the styrenic resin composition is 2 g / 10 min or more, extrusion at a high temperature is not required, so the amount of oligomers generated in the styrenic recycled resin is low, and the problem of soiling the film is less likely to occur. Moreover, when it is 8 g / 10 minutes or less, sufficient stretch orientation is obtained and the film strength is excellent.

  In particular, the present inventor, in a packaging film comprising a biaxially stretched film mainly containing a styrene resin composition, preferably uses a styrene recycled resin, more preferably a styrene recycled resin having an MFR of 4 to 7 g / 10 min. By using a styrene-based resin composition containing 40 to 98% by mass with respect to the total amount (100 mass) of the styrene-based resin composition, the tear strength per unit thickness can be more appropriately set in a thick product with waist. As a result, it has been found that the straight-cut property at the time of separation is further improved in addition to the manual opening of the film.

(Method for manufacturing packaging film)
The biaxially stretched film is produced by melting and kneading the styrenic resin composition, additives and the like and extruding the sheet from a T-die, and then simultaneously biaxially stretching or sequentially biaxially stretching, A known method such as bubble stretching (inflation method) may be employed after kneading and extruding from a cylindrical die into a cylindrical shape.

  In the manufacturing method of the packaging film of this embodiment, the extrusion temperature is preferably 160 to 240 ° C, more preferably 180 to 220 ° C, from the viewpoint of lowering the molecular weight of the styrene-based recycled resin.

In the manufacturing method of the packaging film of the present embodiment, the stretching temperature is in the range of (Vicat softening point of styrene-based resin composition + 10 ° C.) to (Vicat softening point of styrene-based resin composition + 60 ° C.). is important. If the stretching temperature is less than (Vicat softening point of styrene-based resin composition + 10 ° C.), the film cannot be stably formed, and the film breaks or the bubble bursts. If it exceeds (Vicat softening point of styrene resin composition + 60 ° C.), sufficient stretch orientation cannot be obtained, and practical film strength cannot be obtained.
The Vicat softening point of the styrene resin composition can be adjusted by the MFR of the styrene resin contained in the styrene resin composition or the mixing ratio, and is preferably 80 ° C. to 110 ° C., more preferably 100 ~ 105 ° C. The Vicat softening point can be measured according to JIS K7206.

Moreover, in order to obtain sufficient stretch orientation, it is essential that the stretch ratio is 4 to 15 times in both the machine direction (MD) and the cross direction (TD). Above all, from the viewpoint of further excellent winding tightening and hand cutting / straight cut after packaging, the stretching ratio in the direction corresponding to the length direction of the packaging film should be higher than the stretching ratio in the direction corresponding to the width direction. Is preferred.
When the draw ratio is 4 times or more, the stretch orientation is sufficient and an excellent tear strength can be obtained. Further, from various experiments by the present inventors, stable stretching (stretching that does not cause film breakage, bubble burst, and thickness non-uniformity) at 15 times or less is possible. The stretching temperature is selected in the above range, but in the range of the stretching ratio of 4 to 10 times, (the Vicat softening point of the styrenic resin composition + 10 ° C.) to (the Vicat softening point of the styrene resin composition + 50 ° C.), In the range of more than 10 times and 15 times or less, (Vicat softening point of styrenic resin composition + 20 ° C.) to (Vicat softening point of styrene resin composition + 60 ° C.) is preferable.

(Characteristics of packaging film)
The shape of the packaging film of this embodiment in a plan view may be a polygonal shape such as a rectangular shape, a circular shape, or the like, and is preferably a rectangular shape from the viewpoint of efficient production.
Here, the packaging film of the present embodiment has a length direction, a winding direction (circumferential direction) when the packaged container is wound, a direction straddling the container body and the lid of the packaged container, film production It is good also as MD direction of time (refer FIG. 1, 2). For example, in a rectangular packaging film, the extending direction of the long side may be the length direction. The width direction refers to a direction (for example, TD direction) orthogonal to the length direction.
As for the size of the packaging film, for example, the length is (length to wind the container to be wrapped × 0.01) to (length to wind the container to be wrapped × 1.15), and the width is (to be wrapped) The width of the container is preferably 0.03) to (the width of the container to be wrapped x 0.75), and more preferably the length (the length of winding the container to be wrapped x 0.05) to (the packaged object) The length of the container to be wound × 1.10) and the width (width of the packaged container × 0.06) to (width of the packaged container × 0.6).

The packaging film of this embodiment may be heated in a microwave oven together with the package, and the thermal shrinkage in the length direction and width direction of the packaging film at 110 ° C. corresponding to the vapor temperature of the contents is 1% or more. It is preferable to appropriately select the stretching temperature and the stretching ratio so as to be 15% or less.
When the heat shrinkage rate at 110 ° C. is 1% or more, the film is stretched, the packaging appearance is excellent, and the film is tightened and is difficult to come off. When the shrinkage rate at 110 ° C. is 15% or less, the tape is too shrunk and difficult to peel off, and packaging with an appropriate force is possible. The belt is properly wound around the package.
In addition, the heat shrinkage rate at 110 ° C. can be measured by the method described in Examples described later (the measurement direction is changed for each evaluation).

The packaging film has a thickness (t) of 30 μm to 80 μm, preferably 40 μm to 80 μm. In particular, 40-80 μm is preferable for banding or sealing, and 30-50 μm is preferable for tape. The thickness is adjusted so that the value of loop stiffness (L: measured value of loop stiffness tester manufactured by Toyo Seiki Seisakusho Co., Ltd.) corresponding to the waist strength (bending elasticity) suitable for handling is 3 gf or more and 50 gf or less. It is preferable to do.
In addition, the thickness of a packaging film and loop stiffness can be measured by the method as described in the below-mentioned Example.

  The tear strength (R) of the packaging film is preferably 40 mN or more and 100 mN or less in at least one direction of the film from the viewpoint of practical strength and hand cutting property as a packaging film. When the tear strength (R) is 40 mN or more, the film has excellent practical strength as a packaging film, and when it is 100 mN or less, the tear strength by hand is excellent. Note that at least one direction may be any one direction on the surface composed of the length direction and the width direction. Further, at least one direction may be a length direction or a width direction, or a width direction.

The packaging film has, as tear strength per unit thickness (R / t), per unit thickness in the at least one direction from the viewpoint of straight cut performance at the time of hand-opening the banding or banding or cutting the tape. The tear strength (R / t) is 1 mN / μm or more and less than 1.7 mN / μm, and preferably 1 mN / μm or more and less than 1.2 mN / μm. When the tear strength (R / t) per unit thickness is less than 1 mN / μm, the film base material strength is weak, and the film may be unintentionally cut as a packaging film. At 1.7 mN / μm or more, for example, in the transverse direction In addition, when tearing or cutting by hand, the tearing direction may bend from the side to the length, and opening or cutting may not be possible. The packaging film of this embodiment preferably has a tear strength per unit thickness in the above range at least in the width direction.
Further, from the viewpoint of further improving the straight cut property, the ratio of the tear strength (R ₂ , unit mN) in the direction orthogonal to the arbitrary one direction to the tear strength (R ₁ , unit mN) in any one direction ( R ₂ / R ₁ ), for example, the ratio of the tear strength (R _W , unit mN) in the width direction to the tear strength (R _L , unit mN) in the length direction (R _W / R _L ) in the width direction From the viewpoint of the straight cut property of the film, it is preferably less than 1.0, but when the tear strength (R / t) per unit thickness in at least one direction falls within the above range, when the film is manually opened or cut off. It was found that the straight-cutting property was further improved, and the packaging film of the present invention was invented.
The tear strength per unit thickness can be adjusted mainly by blending a styrene-based recycled resin having an MFR of 4 to 7 in addition to the draw ratio.
The tear strength can be measured by the method described in Examples described later (the measurement direction is changed for each evaluation).

  The packaging film of the present embodiment can be used, for example, for packaging food containers such as lunch boxes and side dishes with a lid, collective packaging for printed materials, books, stationery, and the like.

(Banding, banding)
The banding or banding of the present embodiment preferably includes the packaging film of the present embodiment, and more preferably comprises only the packaging film of the present embodiment.

The shape of the banding or banding in a plan view may be a polygonal shape such as a rectangular shape, a circular shape, or the like. From the viewpoint of efficient production, a substantially rectangular shape is preferable.
As for the size of the banding or sealing, for example, the length is (the length of winding the packaging container × 1.01) to (the length of winding the packaging container × 1.15), and the width is (covering The width of the packaging container × 0.25) to (the width of the packaged container × 0.75) is preferable, and the length (the length of winding the packaged container × 1.05) to (covered) is more preferable. The length of winding the packaging container × 1.10) and the width (width of the packaged container × 0.3) to (width of the packaged container × 0.6).
The thickness of the banding or sealing may be the same as the total length or may be different. As for the thickness of the banding or banding, it is preferable that the average thickness of the entire length satisfies the relationship of the above formula (1), and satisfies the relationship of the above formula (1) at any position in the length direction. Is more preferable.

The banding or banding may consist of one sheet of the packaging film, or two or more of the packaging films bonded together.
The banding or banding is a packaging film having a heat shrinkage rate in the length direction at 110 ° C. of 1 to 15% from the viewpoint of excellent winding of a container to be packaged and excellent appearance. The film for packaging may be sufficient, and what joined two or more films for packaging may be sufficient.
Among them, 110 ° C. includes a packaging film having a lengthwise heat shrinkage of 1 to 5% at 110 ° C. and a packaging film having a lengthwise heat shrinkage of 5 to 15% at 110 ° C. Banding or band sealing formed by joining two or more types of packaging films having different heat shrinkage rates in the length direction is preferable. In particular, when a container composed of a container body and a lid is to be banded, a portion having a low heat shrinkage rate is disposed on the top surface (lid body) of the container, and a portion having a high heat shrinkage rate is disposed on the bottom surface (bottom surface of the container body) Thus, the outer appearance of the band on the top surface of the package body after heat shrinkage and the winding effect due to the shrinkage of the bottom surface of the package body are improved.

As a method of joining two or more packaging films in the case of joining two or more packaging films, a tape having an adhesive layer disposed on at least one surface of a packaging film of the present embodiment described later is used. Examples include a method of bonding using an adhesive, a method of bonding using an adhesive, and a method of bonding by heat sealing.
Above all, by aligning the direction of the packaging film to be joined and the tape used for joining that satisfies the relations of the formulas (1) and (2) (for example, aligning the length direction), it is possible to cut and straight cut at the joint. From the viewpoint of obtaining a package having excellent properties, a method of joining using a tape in which an adhesive layer is disposed on at least one surface of the packaging film of the present embodiment is preferable.

(Tape, label)
The tape or label of this embodiment is preferably a tape or label in which an adhesive layer is disposed on at least one surface of the packaging film of this embodiment.
The pressure-sensitive adhesive layer may be provided on both sides of the packaging film or may be provided on one side. Moreover, the said adhesive layer may be provided in the whole surface of the film for packaging, and may be provided in a part. Further, the pressure-sensitive adhesive layer provided on the surface of the packaging film may be the same pressure-sensitive adhesive layer or a combination of different pressure-sensitive adhesive layers.

  As said adhesive layer, the adhesive layer which consists of adhesives, such as an acrylic adhesive, a rubber adhesive, a silicone adhesive, and a urethane adhesive, is mentioned, for example.

The shape of the tape or label in a plan view may be a polygonal shape such as a rectangular shape, a circular shape, or the like. From the viewpoint of efficient production, a substantially rectangular shape is preferable.
The size of the tape only needs to ensure a size that can be attached and sealed from above so that a fitting portion of a food container such as a lunch box or side dish with a lid is not easily opened.
The thickness of the tape may be the same as the total length or may be different. The thickness of the tape is preferably such that the average thickness of the tapes satisfies the relationship of the above formula (1), and more preferably satisfies the relationship of the above formula (1) at any position in the length direction. .

(Packaging body)
The package of the present embodiment is a package in which a package (packaged object) such as a container or an assembly to be packaged is wrapped with the packaging film, the banding, the banding, the tape, the tape, A package with a label attached is preferred.
Part of the surface of the packaged object may be packaged, or the entire surface of the packaged object may be packaged.

  In the packaging body of this embodiment, a packaging film or the like is wound and wound in a winding direction (circumferential direction) when winding the packaged container, and in a direction straddling the container body and the lid of the packaged container. It is preferably used by tearing so that a tear line is formed in a direction perpendicular to the tightening direction.

As shown in FIG. 1, the packaging body of the present embodiment is a packaging in which the banding 3 of the present embodiment is wound and tightened in the circumferential direction of an article A to be packaged consisting of a container body 1 and a lid body 2. It may be a body. The banding 3 in FIG. 1 is a banding in which two or more packaging films are bonded at the bonding portion S. In the banding 3, different packaging films are arranged on the container top surface 31 and the container bottom surface 32, respectively, and the joint portion S is located on the container side surface.
In addition, as shown in FIG. 2, the packaging body of the present embodiment is configured to cover the container body 1 and the lid body 2 of the package A including the container body 1 and the lid body 2. The package body which stuck the tape 4 may be sufficient. When packaging the article A to be packaged consisting of the container body 1 and the lid body 2 with the tape 4, it is preferable to attach the tape at a position across the container body 1 and the lid body 2 in at least two places.
1 and 2 show the MD direction and the TD direction of the packaging film. In the example of FIGS. 1 and 2, the length direction of the banding and the tape is the MD direction.

  As the above-mentioned packaged items, containers containing contents such as food, single items and aggregates such as printed matter, books and stationery, containers composed of a lid and a body that can be heated and tightened, etc. Is mentioned.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

  The materials used in the examples and comparative examples are as follows.

[General-purpose polystyrene resin]
Grade names 685 (MFR: 2.5 g / 10 min) and 679 (MFR: 18 g / 10 min) manufactured by PS Japan Co., Ltd. were used as GPPS for general-purpose polystyrene.
As impact-resistant polystyrene (HIPS: high impact polystyrene), grade name H8672 (MFR: 4.0 g / 10 min) manufactured by PS Japan Co., Ltd. was used.

[Styrene-based recycled resin]
Biaxially stretched polystyrene sheet (grade name: # 710, manufactured by Sandic Co., Ltd.) is separated and collected by hot plate pressure air forming machine into a transparent lid for food containers such as lunch boxes and prepared dishes. After pulverization, the pellets were repelletized by a pelletizer. The extrusion temperature at the time of the re-pellet was set to 180 ° C., 200 ° C., or 220 ° C., and polystyrene recycled resin pellets having different MFR were obtained (MFR: 4.1 g / 10 min, 5.1 g / 10 min, 6.3 g). / 3/10 type).

  The method for analyzing the properties of the packaging films obtained in the examples and comparative examples is as follows.

(1) Thickness The thickness of the packaging film was measured with a dial gauge based on JIS B7503.

(2) Tear strength, hand cutting property The packaging film was cut into a width of 50 mm and a length of 63.5 mm, and the width of the packaging film sample was measured by Elmendorf Tear Tester (manufactured by Toyo Seiki Seisakusho) in accordance with JIS P8116. The tear strength in the direction (R _w : mN) and the tear strength in the length direction (R _L , unit mN) were measured. In the measurement of tear strength, the width direction of the cut packaging film corresponds to the TD direction.
Moreover, the packaging film was cut by hand in the width direction according to the following evaluation criteria, and hand cutting properties were determined.
Good (O): The tear strength in the width direction was 40 mN or more and 100 mN or less, and the film strength and hand cutting properties were excellent.
Poor (x): The tear strength in the width direction was less than 40 mN, the film was easily torn, and the film strength was poor. Alternatively, the tear strength in the width direction exceeded 100 mN, the tearability by hand was inferior, and the tear resistance was strong.

(3) Straight-cutting property Prepare 10 packaging film samples cut into a packaging film with a width of 50 mm and a length of 63.5 mm, tear them in the width direction by hand, and tear lines linearly in the width direction Whether it propagated or not was determined by the following evaluation criteria. In addition, in the evaluation of the linear cut property, the width direction of the cut packaging film corresponds to the TD direction.
Excellent (◎): All 10 sheets were torn linearly in the width direction and had excellent straight cut properties.
Good (O): Only 1 to 2 tear surfaces were displaced from the width direction, but showed good straight-cut properties.
Defect (x): The tear surface was shifted from the width direction when the number of sheets was 3 or more, and the straight cut property was poor.
Furthermore, using the thickness and tear strength obtained from (1) and (2) above, the tear strength per unit thickness in the width direction (R _w / t) and the tear strength in the length direction (R _L) The ratio of the tear strength (R _w , unit mN) in the width direction to the unit mN) (R _w / R _L ) The tear strength in the width direction relative to the length direction was calculated.
(Tear strength per unit thickness: unit mN / μm) = (Tear strength in the width direction: unit mN) / (Thickness: unit μm)
(Ratio of tear strength in width direction to tear strength in length direction) = (Tear strength in width direction: unit mN) / (Tear strength in length direction: unit mN)
In Comparative Examples 4 to 10, there was no direction in which the tear strength (R / t) per thickness unit thickness was 1 or more and less than 1.7.

(4) Loop stiffness A film sample for packaging is cut into a width of 15 mm and a length of 150 mm, and a film is prepared using a stiffness tester (trade name: Loop stiffness tester, loop length is 50 mm, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The rigidity (gf) was measured. The loop stiffness was measured under the conditions of a measurement temperature of 23 ° C., a compression speed of 3.3 mm / second, and an indentation depth of 11 mm.
Moreover, the waist of the packaging film was determined according to the following evaluation criteria. In addition, the width direction of the cut out packaging film corresponds to the TD direction.
Good (O): The loop stiffness was 3 gf or more and 50 gf or less, there was a moderate waist, and it was suitable for a packaging film.
Defect (x): Loop stiffness was less than 3 gf, the film was weak and too soft to handle. Alternatively, the loop stiffness was more than 50 gf, the film was strong and hard, and did not follow the package.

(5) Thermal shrinkage rate and appearance A sample of a packaging film is prepared in accordance with ASTM D2732, and immersed in a silicone oil bath at a temperature of 110 ° C. for 30 seconds. The length of the sample before immersion and the length of the sample after immersion From this, the heat shrinkage rate (%) in the length direction and width direction was determined.
In addition, wrapping a packaging film containing food (such as lunch box, side dish, etc. (width: 200mm, length: 150mm, thickness: 70mm)) with a wrapping film band (width: 120mm, length: 495mm). The overlapping portions (width 120 mm, length 10 mm) were stuck with a tape coated with an adhesive on the packaging film, and then shrink-wrapped by applying hot air at 110 ° C. from the bottom of the packaging container. The tape and the banding were bonded so that the length direction and the width direction coincided. Moreover, the part (joining part) which wound and overlapped was provided in the side surface of the packaging container.
And the shrinkage | contraction property of banding was determined with the following evaluation criteria.
Good (◯): The heat shrinkage rate in the length direction and the width direction was 1% or more and 15% or less, the banding was moderately shrunk, and the package had a good appearance.
Defect (x): The heat shrinkage rate in at least one of the length direction and the width direction is less than 1%, there is no tension on the banding, the packaging appearance is inferior, the banding seal is loose, and the banding is loose I missed it. Or (the thermal shrinkage rate in at least one of the length direction and the width direction is more than 15%, and the shrinkage in the width direction of the banding is greatly different between the corner portion and the flat portion of the packaging container and the appearance is inferior. Or, due to excessive shrinkage in the length direction of the banding, the banding was too tight and the appearance was inferior.

(6) Comprehensive evaluation The packaging film was comprehensively evaluated according to the following evaluation criteria.
Excellent (◎): Good hand cutting performance and excellent straight cut performance.
Good (◯): The hand cutting property and the straight cut property were good.
Defect (x): Hand cutting property and / or straight cut property were unsatisfactory.

[Examples 1-4 and Comparative Examples 1-3]
General purpose polystyrene resins GPPS and HIPS and polystyrene styrene regenerated resin were dry blended to obtain a styrene resin composition having an MFR of the same melt viscosity at 4.1 g / 10 min. This styrenic resin composition is supplied to an extruder having a 65 mm diameter screw, melt-kneaded, and the styrenic resin composition is extruded with a cylindrical die at a temperature of 180 ° C., with a longitudinal draw ratio of 7.5 times and a transverse draw ratio of 6 5 was bubble-drawn to obtain a film and wound into a roll. Table 1 shows the mixing ratio of the styrene resin contained in the styrene resin composition, the film thickness, and the like.
Examples 1 to 4 are thin and thick packaging films, and the balance between film strength and hand cutting properties was good. Especially the packaging film of Examples 2-4 was excellent in the rectilinear cutting property of the width direction, and was excellent also in the external appearance.
Comparative Examples 1 and 2 are thin and weak, inferior in practical strength such as film tearing as a packaging film, and due to excessive shrinkage in the length direction, the band is too tightly wrapped around the package, and the appearance It was inferior to.
In Comparative Example 3, the packaging film was strong, the packaging film did not follow the package, and the hand cutting property was inferior.

[Comparative Examples 4 to 7]
Except for the addition of styrene-based recycled resin, dry blending of general-purpose polystyrene resins GPPS and HIPS to obtain a styrene-based resin composition having the same melt viscosity at MFR of 4.1 g / 10 min was carried out in the same manner as in Example 1. Thus, a packaging film was obtained. Table 1 shows the mixing ratio of the styrene resin contained in the styrene resin composition, the film thickness, and the like.
Comparative Examples 4 to 7 are thin and thick packaging films, which have a good balance between film strength and hand cutting properties, but are inferior in straight-ahead cutability and difficult to open.

[Comparative Examples 8 to 10]
Commercially available unstretched polystyrene film (Comparative Example 8, commercially available CPS, manufactured by Towa Chemical Industry Co., Ltd., trade name “stylon film”), commercially available biaxially stretched polypropylene film (Comparative Example 9, commercially available OPP, manufactured by Santox Co., Ltd., trade name) Table 1 shows the properties of “Santox OP”) and a commercially available biaxially stretched polyester film (Comparative Example 10, commercially available PET, manufactured by Toyobo Co., Ltd., trade name “Toyobo Ester Film”).
Both are inferior in straight-cutting properties, difficult to open and cut by hand, and commercially available CPS and commercially available PET are inferior in hand-cutting properties, and commercially available PET has no heat shrinkability at 110 ° C. and has an appearance at shrink packaging. Was also inferior.

In particular, the packaging film of Example 4 cut into a width of 120 mm and a length of 257 mm and the packaging film of Example 2 cut into a width of 120 mm and a length of 257 mm over the entire width direction at the end in the length direction. The portions that were wound and overlapped (width 120 mm, length 10 mm, joint portion) were bonded together using a tape in which an adhesive was applied to the packaging film of Example 4 to produce a banding.
A wrapping container containing food such as a bento box or side dish (substantially rectangular parallelepiped having a width of 200 mm, a length of 150 mm, and a thickness of 70 mm) was covered with the band and wound. The packaging film of Example 4 is placed on the top surface of the packaging container and the packaging film of Example 2 is placed on the bottom surface of the packaging container, and the packaging film of Example 2 and the packaging film of Example 4 are placed on the side of the packaging container. The joint part with was arranged.
Shrink packaging was performed by applying hot air of 110 ° C. from the bottom of the packaging container. As for the appearance after heat shrinkage, the shrinkage on the top of the container was small, there was tension, and the printing readability was good. Moreover, the winding effect by shrinkage | contraction from the bottom face of a heat-packaging body also became favorable, and the external appearance of the shrink wrapping was also excellent.

  The packaging film of the present invention is a packaging film having improved straight-cut performance when manually opening and cutting a thick, thick material. Furthermore, for packaging consisting of biaxially stretched film mainly composed of styrene resin containing specific styrene resin and styrene resin that has been increased in the ratio of recycled raw materials due to increased environmental awareness and resource saving. It is preferably a film, and can be suitably used as a banding or sealing, tape or label, and a package using these, which are excellent in the appearance of shrink wrapping.

A: Packaged object 1: Container body 2: Cover body 3: Banding 31: Container top surface 32: Container bottom surface S: Joint part 4: Tape

Claims (8)

A packaging film composed of a biaxially stretched film mainly containing a styrene resin composition,
The thickness (t: unit μm) of the packaging film and the tear strength (R: unit mN) measured in accordance with JIS P8116 satisfy the following formulas (1) and (2). A packaging film characterized by filling.
30 ≦ t ≦ 80 (1)
1 ≦ R / t <1.7 (2)   The packaging film according to claim 1, wherein the styrene resin composition contains 40 to 98% by mass of a styrene recycled resin having an MFR of 4 to 7 g / 10 min.   The packaging film according to claim 1 or 2, wherein the packaging film has a heat shrinkage in the length direction and the width direction at 110 ° C of 1 to 15%.   A banding or banding comprising the packaging film according to any one of claims 1 to 3.   Heat in the length direction at 110 ° C. including a packaging film having a heat shrinkage rate in the length direction of 1 to 5% at 110 ° C. and a packaging film having a heat shrinkage rate in the length direction of 110 ° C. of 5 to 15% The banding or banding according to claim 4, wherein two or more types of packaging films having different shrinkage rates are joined.   A package body, characterized in that it is packaged with the banding or banding according to claim 4 or 5.   A tape or label, wherein an adhesive layer is disposed on at least one surface of the packaging film according to any one of claims 1 to 3.   A package, wherein the tape or label according to claim 7 is attached.

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