JP2019194105A - Stretch wrapping film - Google Patents

Abstract

To provide a stretch wrapping film for food wrapping that is not broken even subjected to external force caused by vibration in a low temperature state and that has good packaging suitability for an automatic wrapping machine.SOLUTION: The stretch wrapping film has at least one layer composed of a thermoplastic resin composition comprising the following components (A) and (B) as essential components and has 100 MPa to 1 GPa of storage modulus(E) at 20°C measured at a vibration frequency of 10 Hz by a dynamic viscoelasticity measuring method. (A) A component comprising at least one resin selected from propylene-ethylene copolymer, propylene-α-olefin copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-α-olefin copolymer, block polypropylene and homopropylene. (B) a component comprising at least one resin selected from ethylene-α-olefin block copolymer and ethylene-α-olefin random copolymer.SELECTED DRAWING: None

Description

  The present invention relates to a stretch packaging film that is suitably used for food packaging, and more particularly to a stretch packaging film that does not contain chlorine or a polyvinyl chloride plasticizer that is used for freezing packaged food.

  Conventionally, a polyvinyl chloride film has been mainly used as a film that overlaps by placing fruits and vegetables, meat, fresh fish, prepared dishes, etc. on a lightweight tray, that is, a stretch packaging film for so-called pre-packaging. The reason for this is that the polyvinyl chloride film has good packaging efficiency and a good packaging finish such as a beautiful packaging finish, and returns to its original state when the film after packaging is deformed by pressing with a finger. It was recognized by both sellers and consumers that the product value does not decrease, such as excellent elasticity recovery, good bottom folding stability, and less film peeling during transportation display. This is because of the superiority of quality.

  However, in recent years, with respect to polyvinyl chloride films, problems such as elution of hydrogen chloride gas generated during incineration and plasticizers contained in large quantities have been regarded as problems. For this reason, various alternatives to polyvinyl chloride films have been studied, and various stretch packaging films using polyolefin resins have been proposed. Above all, for reasons such as good surface properties as a film for stretch packaging, transparency, moderate heat resistance, freedom of material design, economy, etc., ethylene-vinyl acetate copolymer is used as the main component in the front and back layers, 2. Description of the Related Art Stretch wrapping films having a two-layer / three-layer structure using various types of polypropylene-based resin as an intermediate layer are being actively studied.

  In recent years, food freezing technology has advanced for the purpose of maintaining the freshness of food. Traditionally, fruits and vegetables, meat, fresh fish, and prepared dishes have been packaged in stores. However, large supermarkets and other stores have gathered the packaging locations for fruits and vegetables, meat, fresh fish, and prepared dishes (pack center). ), And after the packaging, there is a tendency that the business form of transporting while freezing to each store is increasing, and the distribution of frozen food is increasing.

  In these distribution forms, food trays are packed in an automatic packaging machine at room temperature, transported to each destination after packaging, transported in a frozen state, and placed in storefront showcases for general consumers. Will be provided. Moreover, since transportation efficiency is also considered, it is normally conveyed in the state laminated | stacked on about 4-5 packs. For this reason, the package which wraps food receives external force by the contact at the time of movement of food, and the vibration at the time of transportation under low temperature (-40 degreeC--15 degreeC). From the above, there has been a demand for development of a film for stretch packaging that is not broken even when subjected to external force at a low temperature of −40 ° C. to −15 ° C.

  In Patent Document 1, the intermediate layer is a layer containing any one of propylene-based resin and petroleum resin, terpene resin, coumarone-indene resin, rosin resin, or hydrogenated derivatives thereof, and has a specific storage elasticity at 20 ° C. Two types and three layers of stretch packaging films for food packaging having a rate have been proposed.

  Patent Document 2 proposes a stretch packaging film containing a polyethylene resin as a main component and having a tan δ at −30 ° C. of 0.15 or more.

JP 09-154479 A JP 2002-338704 A

  Here, the film of Patent Document 1 has a low loss tangent (tan δ) at a low temperature when the film is used for refrigerated transportation as described above, so the impact strength at a low temperature is low, and the film is torn during transportation. There is a possibility that. In addition, the film of Patent Document 2 has improved impact strength at the time of freezing transport, but a film mainly composed of polyethylene resin has a strong repulsion when it is packaged by an automatic packaging machine at room temperature. When pulling out and pulling and packaging, wrinkles may remain after packaging and the tray may be deformed.

  The present invention has been made in view of the above circumstances, and even when a package body in which food is packaged is subjected to external force due to contact during movement of food or vibration during transportation at low temperatures (-40 ° C to -15 ° C). An object of the present invention is to provide a stretch wrapping film for food wrapping that is not broken and has good wrapping ability by an automatic wrapping machine.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by a film having a specific configuration, and have completed the present invention.

That is, the gist of the present invention is to have at least one layer composed of a thermoplastic resin composition having the following components (A) and (B) as essential components, and a vibration frequency of 10 Hz by a dynamic viscoelasticity measurement method. The film for stretch packaging has a storage elastic modulus (E ′) measured at 20 ° C. of 100 MPa to 1 GPa at 20 ° C.
(A) Propylene-ethylene copolymer, propylene-α-olefin copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-α-olefin copolymer, block polypropylene, homopropylene Component (B) composed of at least one resin selected from the group consisting of ethylene-α-olefin block copolymer and ethylene-α-olefin random copolymer

  According to the present invention, the packaged trays are stacked in a stack of about 4 to 5 packs, stored at a low temperature (−40 ° C. to −15 ° C.), and in a frozen state, they are torn by impact generated during transportation. In addition, it is possible to provide a film for non-chlorine stretch packaging having good suitability for various packaging machines when an automatic packaging machine is used.

  Hereinafter, a stretch packaging film (hereinafter, may be abbreviated as a stretch film) as an example of an embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

In the present invention, the “main component” includes the meaning of allowing other components to be contained within a range that does not interfere with the function of the main component, unless otherwise specified. At this time, the content ratio of the main component is not specified, but the main component (when two or more components are main components, the total amount thereof) is 50% by mass or more, particularly 70% by mass in the composition. %, More preferably 90% by mass or more (including 100% by mass).

  Further, in the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, “X is preferably greater than X” and “ Is less than Y. Further, in the present invention, when expressed as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and “Y or less” (Y is an arbitrary number). ) Includes the meaning of “preferably smaller than Y” unless otherwise specified.

  Moreover, in the present invention, the “stretch packaging film” is meant to include a wide range of packaging films having stretchability and self-adhesiveness. Typically, pre-packaging packaging films that overlap by placing fruits and vegetables, meat, side dishes, etc. on lightweight trays, and packaging films that overlap to secure the luggage during luggage transportation, etc. .

  In general, “sheet” is a thin product as defined by JIS, and generally its thickness is small and flat instead of length and width, and “film” is generally defined as length and width. A thin flat product having an extremely small thickness and an arbitrarily limited maximum thickness, usually supplied in the form of a roll (Japanese Industrial Standard JISK6900). For example, in terms of thickness, in the narrow sense, a film having a thickness of 100 μm or more is sometimes referred to as a sheet, and a film having a thickness of less than 100 μm is sometimes referred to as a film. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

The stretch packaging film of the present invention has at least one layer composed of a thermoplastic resin composition and has a storage elastic modulus (E ′) at 20 ° C. measured at a vibration frequency of 10 Hz by a dynamic viscoelasticity measurement method of 100 MPa. ~ 1 GPa. The layer made of the thermoplastic resin composition needs to have the following components (A) and (B) as essential components.
(A) Propylene-ethylene copolymer, propylene-α-olefin copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-α-olefin copolymer, block polypropylene, homopropylene Component (B) composed of at least one resin selected from the group consisting of ethylene-α-olefin block copolymer and ethylene-α-olefin random copolymer

  The film for stretch packaging of the present invention has a loss tangent (tan δ) at −30 ° C. measured at a vibration frequency of 10 Hz by a dynamic viscoelasticity measurement method of 0.07 or more, preferably 0.075 or more, 0 More preferably, it is 0.08 or more.

The film for stretch packaging of the present invention has a melt viscosity η (A) of the thermoplastic resin composition (A) component and a melt of the thermoplastic resin composition (B) component under the conditions of a temperature of 200 ° C. and a shear rate of 100 sec ⁻¹ . The ratio η (A) / η (B) of the viscosity η (B) is 0.10 or more and 0.95 or less, or the ratio η (B) / η (A) is 0.10 or more and 0.95 or less. Preferably there is. The lower limit of the ratio η (A) / η (B) or the ratio η (B) / η (A) is more preferably 0.15 or more, and further preferably 0.20 or more. The upper limit of the ratio η (A) / η (B) or the ratio η (B) / η (A) is more preferably 0.92 or less, and even more preferably 0.90 or less.

  The layer made of the thermoplastic resin composition preferably has (C) a component made of a copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof.

  The layer made of the thermoplastic resin composition has (D) at least one component selected from petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof. Is preferred. Moreover, it is preferable that the layer which consists of a thermoplastic resin composition contains an ethylene-vinyl acetate copolymer.

  The stretch packaging film of the present invention may have a layer made of a thermoplastic resin composition containing the predetermined thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component as essential components. By including a thermoplastic resin composition (B) component, it is preferable at the point which can improve the impact resistance in low temperature to a thermoplastic resin composition. The thermoplastic resin composition includes as a main component a resin composition obtained by combining the thermoplastic resin compositions (A) and (B). In the layer made of the thermoplastic resin composition, the total amount of the thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component is 50% or more and 100% or less of the total amount, and the (A) component / (B) It is preferable that the mass ratio of a component is 0.5 or more and 2.0 or less.

  The film for stretch packaging of the present invention is suitable for packaging machines (cutting properties, packaging wrinkles, bottom folding stability, tearability, transparency after packing), and the amount of crystallization (ΔHc) of the thermoplastic resin composition. ) Within a predetermined range (10 J / g or more and 60 J / g or less). When the heat of crystallization is 10 J / g or more, the crystallinity is too low and the film-forming property is deteriorated. In addition, the film is too soft at room temperature or the strength is insufficient. This can be suppressed. Moreover, by setting the amount of heat of crystallization to 60 J / g or less, a large force is required at the time of stretching the film, and only non-uniform elongation is exhibited, thereby suppressing the film from being suitable for a stretch packaging film. The method for adjusting the amount of crystallization heat (ΔHc) to a predetermined range is not particularly limited, but a method of mixing a plurality of different resins is preferably used. For example, the thermoplastic resin composition of the stretch wrapping film is mixed with the thermoplastic resin composition (C) component so that the heat of crystallization (ΔHc) is within a predetermined range (10 J / g or more and 60 J / g or less). This is preferable because it can be performed.

<Thermoplastic resin composition (A)>
The thermoplastic resin composition (A) component may be a propylene homopolymer, or a propylene resin such as a random copolymer or block copolymer with another monomer copolymerizable with propylene. Well, in propylene-ethylene copolymer, propylene-α-olefin copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-α-olefin copolymer, block polypropylene, random polypropylene, homopropylene It consists of at least 1 type of resin chosen from these.

  By containing such a propylene-based resin, various packaging suitability such as bottom folding and cutting properties can be improved, and in addition to pellet storage stability, the strength and heat resistance of the resin composition constituting the intermediate layer can be improved. Can be increased.

  In this case, other monomers copolymerizable with polypropylene include α-olefins having 4 to 20 carbon atoms such as ethylene, 1-butene, 1-hexene, 4-methylpentene-1, 1-octene, and divinyl. Although dienes, such as benzene, 1, 4- cyclohexadiene, dicyclopentadiene, cyclooctadiene, ethylidene norbornene, etc. are mentioned, These 2 or more types may be copolymerized.

  From the viewpoint of imparting appropriate flexibility necessary for the stretch packaging film of the present invention, the thermoplastic resin composition (A) component comprises a propylene-ethylene copolymer, a propylene-ethylene-butene-1 copolymer, It is preferable to use at least one component selected from propylene-α-olefin copolymer, propylene-ethylene-α-olefin copolymer, and block polypropylene.

  The melt flow rate (MFR) of the thermoplastic resin composition (A) is not particularly limited, but usually MFR (JISK7210, temperature: 230 ° C., load: 21.18 N) is 0.2 g to 20 g. / 10 minutes, preferably 0.5 to 18 g / 10 minutes, more preferably 1 to 15 g / 10 minutes. If the MFR is 0.2 g / 10 min or more, the extrusion processability is stable. If the MFR is 20 g / 10 min or less, stable film formation is possible at the time of molding, as well as unevenness in thickness, decrease in mechanical strength, and variation. Etc. are preferable.

  Examples of the propylene-based resin that can be used as a component of the thermoplastic resin composition (A) include a propylene homopolymer, a random copolymer with other monomers copolymerizable with propylene, and a block copolymer. Propylene-based resins such as polymers are trade names “Novatech PP” and “WINTEC” of Nippon Polypro Co., Ltd., “Nobrene” of Sumitomo Chemical Co., Ltd., and “Prime Polypro” trade names of Prime Polymer Co., Ltd. Prime TPO ", Dow Chemical Co., Ltd. trade name" Versify ", and the like.

  The content of the thermoplastic resin composition (A) component (ratio to the total amount of the layer made of the thermoplastic resin composition) is preferably 1 to 50% by mass. The lower limit of the thermoplastic resin composition (A) component is more preferably 12.5% by mass or more, and further preferably 15% by mass or more. The upper limit of the thermoplastic resin composition (A) component is preferably 45% by mass or less, and more preferably 40% by mass or less. If the content of the resin (A) is 1% by mass or more, the layer made of the thermoplastic resin composition can improve various packaging suitability such as bottom folding and cutting required for the stretch packaging film, and The strength and heat resistance of the resin composition constituting the intermediate layer can be increased, and if it is 50% by mass or less, the strength and heat resistance of the resin composition can be increased and impact resistance at low temperatures can be imparted. It is preferable from the viewpoint of achieving both.

<Thermoplastic resin composition (B)>
Examples of the thermoplastic resin composition (B) component include ethylene-olefin copolymers such as ethylene-α olefin block copolymers and ethylene-α olefin random copolymer ethylene resins. It is preferable that it is a component which consists of at least 1 sort (s) of resin chosen from the inside. The copolymer containing the ethylene component that becomes the hard segment and the α-olefin component that becomes the soft segment has heat resistance due to the hard segment, flexibility due to the soft segment, and low temperature characteristics, and other resin components can be added even in small amounts. Can contribute to low temperature characteristics and impact resistance at low temperatures.

  Examples of the α olefin forming the soft segment of the ethylene-α olefin block copolymer include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1 Although -dene etc. are mentioned, when it considers a softness | flexibility and an easiness to process, 1-octene is preferable. Examples of the ethylene-α-olefin block copolymer include XLT series of trade name “Engege” of Dow Chemical Co., Ltd., trade name “Infuse”, and the like.

  Examples of the α olefin forming the soft segment of the ethylene-α olefin random copolymer include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1 Although -dene etc. are mentioned, when it considers a softness | flexibility and an easiness to process, 1-octene is preferable. As the ethylene-α-olefin random copolymer, trade names “Evolue” and “Neozex” of Prime Polymer Co., Ltd. can be exemplified.

The density of the ethylene -α-olefin copolymer from the viewpoint of low-temperature impact resistance, preferably at 0.89 g / cm ³ or less, more preferably at 0.88 g / cm ³ or less. On the other hand, the lower limit is not particularly limited, but is usually 0.85 g / cm ³ .

  Moreover, the stretch packaging film of the present invention has a layer composed of a thermoplastic resin composition as an intermediate layer, and when the surface layer has a surface layer on at least one surface, the surface layer contains this thermoplastic resin composition (B) component. The ethylene resin may be the same ethylene resin as the constituent ethylene resin or may be a different ethylene resin, but it is preferably one or a mixture of two or more of the same ethylene resin. When such an ethylene-based resin is mixed, not only contributes to impact resistance at low temperatures as described above, but also when the thermoplastic resin composition (B) component is a mixture of two or more types, If one of them is the same ethylene resin as the ethylene resin constituting the surface layer, the adhesion between the intermediate layer and the surface layer can be improved, and the mechanical properties of the entire film can be improved.

  The melt flow rate (MFR) of the thermoplastic resin composition (B) component is not particularly limited, but usually MFR (JISK7210, temperature: 190 ° C., load: 21.18 N) is 0.2 to 20 g / 10 min, preferably 0.5-18 g / 10 min, more preferably 1-15 g / 10 min. If the MFR is 0.2 g / 10 min or more, the extrusion processability is stable. If the MFR is 20 g / 10 min or less, stable film formation is possible at the time of molding, as well as unevenness in thickness, decrease in mechanical strength, and variation. Etc. are preferable.

  In the layer made of the thermoplastic resin composition, the content of the thermoplastic resin composition (B) component (ratio to the total amount of the layer made of the thermoplastic resin composition) is preferably 1 to 50% by mass. The lower limit of the content of the thermoplastic resin composition (B) component is more preferably 15% by mass or more, further preferably 20% by mass or more, and the upper limit is more preferably 45% by mass or less. More preferably, it is 40% by mass or less.

  If content of a thermoplastic resin composition (B) component is 1 mass% or more, the impact resistance in the low temperature required for the film for stretch packaging used in a frozen environment can be provided. When the content of the thermoplastic resin composition (B) component is 50% by mass or less, the storage elastic modulus of the laminated film including the intermediate layer at 20 ° C. measured at a vibration frequency of 10 Hz by a dynamic viscoelasticity measurement method ( E ′) becomes 100 MPa or more, and various packaging aptitudes such as bottom folding and cutting required for a stretch packaging film can be obtained.

(Melt viscosity)
The melt viscosity η of the thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component is not particularly limited, but is 100 Pa · s at a temperature of 200 ° C. and a shear rate of 100 sec ^−1. It is 10000 Pa · s, preferably 200 Pa · s to 9000 Pa · s, more preferably 300 Pa · s to 8000 Pa · s. If the melt viscosity at a shear rate of 100 sec ⁻¹ is 100 Pa · s or more, stable film formation is possible during molding while maintaining excellent mechanical properties, and if it is 10000 Pa · s or less, extrusion processability is stable. Therefore, it is preferable.
The melt viscosity η of the thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component is measured by the method described in the examples described later.

Here, when the melt viscosity of the thermoplastic resin composition (A) component is “η (A)” and the melt viscosity of the thermoplastic resin composition (B) component is “η (B)”, the temperature is 200 ° C. The relationship between the melt viscosity under the condition of a shear rate of 100 sec ⁻¹ is that the ratio of melt viscosity is η (A) / η (B) of 0.10 or more and 0.95 from the viewpoint of film forming properties and film low temperature impact properties. Or η (B) / η (A) is preferably 0.10 or more and 0.95 or less.
The thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component of the present invention are incompatible, but when mixing thermoplastic resin compositions that are generally incompatible, When the melt viscosities η in the mixing temperature region of the plastic resin composition are close to each other, the dispersion diameter of the thermoplastic resin that becomes the dispersed phase tends to be small and uniformly mixed.

  In the present invention, it is preferable that the melt viscosity η (B) of the thermoplastic resin composition (B) component is appropriately different from the melt viscosity η (A) of the thermoplastic resin composition (A) component. Since the melt viscosity η (B) has an appropriate difference from the melt viscosity η (A), the thermoplastic resin (B) component is easily dispersed uniformly in the layer, and the film-forming property is improved. The dispersion diameter of the plastic resin (B) component becomes an appropriate size, and the low temperature impact resistance of the film is improved.

  As for the ratio of melt viscosity, the lower limit of the ratio of η (A) / η (B) or η (B) / η (A) is more preferably 0.15 or more, and further preferably 0.20 or more. The upper limit of the ratio of η (A) / η (B) or η (B) / η (A) is more preferably 0.92 or less, and further preferably 0.90 or less. If the ratio of melt viscosity is η (A) / η (B) or η (B) / η (A) is 0.10 or more, the dispersion diameter of the component that becomes the dispersed phase in the thermoplastic resin layer Does not become too large, the film-forming property of the film is good, and if it is 0.95 or less, the low-temperature impact property of the film is sufficient.

  The melt viscosity of the thermoplastic resin composition (A) component and the thermoplastic resin composition (B) component need only be appropriately different, and either melt viscosity may be large, but in the present invention, Since the thermoplastic resin composition (B) component contributes to low temperature impact resistance, from the viewpoint of further enhancing the low temperature impact properties of the film, η (A) <η (B) Is more preferable.

<Thermoplastic resin composition (C)>
The film for stretch packaging of the present invention may contain a predetermined thermoplastic resin composition (C) component in the layer composed of the thermoplastic resin composition.

  Examples of the thermoplastic resin composition (C) component include a block copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof. Since such a copolymer generally has rubber elasticity and is flexible, it gives elastic recovery to the stretch packaging film of the present invention and effectively acts on reduction of the tensile elastic modulus.

  Here, styrene is a typical vinyl aromatic compound, but styrene homologues such as α-methylstyrene may also be used. Examples of the conjugated diene include 1,3-butadiene, isoprene, 1,3-pentadiene, and the like. These may be used alone or in combination of two or more. Further, as the third component, a small amount of components other than the vinyl aromatic compound and the conjugated diene may be contained. However, the thermal stability and weather resistance when a double bond mainly consisting of vinyl bonds in the conjugated diene moiety remains are very poor. To improve this, 80% or more of the double bond, and further 95%. It is preferable to use one added with hydrogen.

  Moreover, it is preferable that the ratio of the vinyl aromatic-type compound and conjugated diene of such a copolymer is 3 / 97-40 / 60 by mass ratio. Here, when the vinyl aromatic compound in the copolymer composition is 3% by mass or more, it is preferable that the rigidity is not excessively reduced when a film for stretch packaging is used, and on the other hand, it is 40% by mass or less. When the film for stretch wrapping is used, the effects such as imparting elastic recoverability to the film and reducing the tensile elastic modulus are sufficient without the rigidity being too high.

  Specific examples of the thermoplastic resin composition (C) component include a styrene-butadiene block copolymer elastomer (Asahi Kasei Kogyo Co., Ltd., trade name “Tufprene”), a hydrogenated derivative of a styrene-butadiene block copolymer ( Asahi Kasei Kogyo Co., Ltd. trade name “Tuftec”, hydrogenated derivative of styrene-isoprene block copolymer (Kuraray trade name “Septon”), styrene-vinylisoprene block copolymer elastomer (Kuraray trade name “Co., Ltd.”) Commercially available products such as “Hibler”) can be used.

  In the layer formed of the thermoplastic resin composition, the content of the thermoplastic resin composition (C) component is preferably 1 to 50% by mass. The lower limit of the content of the thermoplastic resin composition (C) component is more preferably 5% by mass or more, further preferably 10% by mass or more, and the upper limit is more preferably 45% by mass or less. More preferably, it is 40% by mass or less. If content of a thermoplastic resin composition (C) component is 1 mass% or more, the elasticity recovery property of a film required for the film for stretch packaging can be provided. Moreover, if it is 50 mass% or less, compatibility with the other component of a thermoplastic resin composition can improve, and transparency can be improved, the elasticity recovery property of a film for stretch packaging is provided, and transparency is improved. It is preferable from the viewpoint of achieving both.

<Thermoplastic resin composition (D) component>
The film for stretch packaging of the present invention may contain a predetermined thermoplastic resin composition (D) component in the layer composed of the thermoplastic resin composition.

  As the thermoplastic resin composition (D) component, for example, at least one component selected from petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof (hereinafter, these are generically named) (Also referred to as “petroleum resins”).

  Such a thermoplastic resin composition (D) component effectively acts for further improvement of packaging suitability such as film waist and cutability, bottom folding stability, and transparency.

  Here, as the petroleum resin, cyclopentadiene or an alicyclic petroleum resin obtained from the dimer thereof, an aromatic petroleum resin obtained from the C9 component, or a copolymer of alicyclic and aromatic petroleum resin A petroleum resin etc. can be mentioned.

  Examples of the terpene resin include a terpene resin obtained from β-pinene and a terpene-phenol resin.

  Examples of the coumarone-indene resin include a thermoplastic synthetic resin obtained by purifying a 160 to 180 ° C. fraction of tar and polymerizing coumarone having 8 carbons and indene having 9 carbons as main monomers.

  Examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.

  The petroleum resin as described above is preferably a hydrogenated derivative from the viewpoints of color tone, thermal stability, and compatibility.

  Moreover, although what has various softening temperatures mainly by molecular weight is obtained as said petroleum resin, what has a softening temperature in 100-150 degreeC, Preferably it is 110-140 degreeC is more suitable.

  Specifically, Mitsui Chemicals' product names “Hilets” and “Petrogin”, Arakawa Chemical Industries' product name “Arcon”, Yashara Chemicals' product name “Clearon”, Idemitsu Petrochemical Co., Ltd. ) And trade name “Escoretz” of Eastman Chemical Co., Ltd. can be used.

  In the layer formed of the thermoplastic resin composition, the content of the thermoplastic resin composition (D) component is preferably 1 to 40% by mass. The lower limit of the content of the thermoplastic resin composition (D) component is more preferably 5% by mass or more, further preferably 10% by mass or more, and the upper limit is more preferably 35% by mass or less. More preferably, it is 30% by mass or less. If the content of the thermoplastic resin composition (D) component is 1% by mass or more, it is preferable because the necessary cut property and bottom folding stability can be imparted to the stretch wrapping film. If the glass transition temperature is increased, the low temperature aptitude necessary for the stretch wrapping film is unlikely to be impaired, and it is also difficult to cause blocking of the film due to low molecular weight bleed.

  The layer made of the thermoplastic resin composition preferably has an ethylene-vinyl acetate copolymer. The ethylene-vinyl acetate copolymer preferably has a vinyl acetate unit content of 5 to 25% by mass. If vinyl acetate unit content is 5 mass% or more, the film obtained will be soft and can maintain a softness | flexibility and elastic recovery property. The layer made of the thermoplastic resin composition has an ethylene-vinyl acetate copolymer, so that, for example, the trimming loss generated when trimming by trimming both ends of the formed film or the production machine that has been stopped. It can be prepared by adding a loss that does not become a product to be sold, such as a film formed in the initial stage of production immediately after start-up, as a constituent material of the intermediate layer. Thereby, waste of material can be eliminated and material cost can be reduced.

  Further, when the stretch packaging film of the present invention has a layer composed of a thermoplastic resin composition and a surface layer, even if the surface layer is the same ethylene resin as the ethylene-vinyl acetate copolymer, a different ethylene Although it may be a resin, it is preferably a mixed component of one or more of the same ethylene resin. If the ethylene-vinyl acetate copolymer is mixed with the layer made of the thermoplastic resin composition so that the ethylene-vinyl acetate copolymer is the same ethylene resin as the ethylene resin constituting the surface layer, the intermediate layer It is possible to improve the adhesion between the film and the surface layer, and to improve the mechanical properties of the entire film. In addition, the film for stretch wrapping containing the ethylene-vinyl acetate copolymer in the surface layer can contain the ethylene-vinyl acetate copolymer in the intermediate layer by using the film for loss in the intermediate layer. The material cost of the surface layer can be reduced, and the adhesion between the surface layer and the intermediate layer can be increased.

<Surface layer>
The film for stretch wrapping of the present invention has a layer made of a thermoplastic resin composition as an intermediate layer, a surface layer is formed on at least one surface of the intermediate layer, and a layer containing an olefin-based resin is arranged on the surface layer. It is possible to improve heat sealability (bottom sealability) at low temperatures, self-adhesiveness, moldability at the time of inflation molding, and the like. In the stretch packaging film of the present invention, it is more preferable to form a surface layer containing an olefin resin on both surfaces of a layer (intermediate layer) made of a thermoplastic resin composition.

Examples of the olefin resin include low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and ethylene-based copolymers such as ethylene and propylene. , Butene-1, pentene-1, wall ship-1, 4-methylpentene-1, heptene-1, octene-1, etc. α-olefins such as vinyl acetate, vinyl propionate, etc. One or more selected from unsaturated carboxylic acid esters such as esters, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate, and their ionomers and unsaturated compounds such as conjugated and non-conjugated dienes Copolymers or multi-component copolymers with these comonomers, or mixtures thereof Etc. can be mentioned.
The ethylene unit content in the ethylene-based polymer is usually preferably more than 50% by mass.

  Among these ethylene resins, low density polyethylene, linear low density polyethylene, linear ultra low density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid ester copolymer, and ethylene-methacrylic acid At least one ethylene-based polymer selected from ester copolymers is preferred. Examples of the acrylic acid ester of the ethylene-acrylic acid ester copolymer include methyl acrylate and ethyl acrylate. Examples of the acrylic acid ester of the ethylene-methacrylic acid ester copolymer include methyl methacrylate. And ethyl methacrylate.

  Among these, as the ethylene-based resin, ethylene having a vinyl acetate unit content of 5 to 25% by mass and a melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18N) of 0.2 to 10 g / 10 min. -A vinyl acetate copolymer is preferable, and an ethylene-vinyl acetate copolymer is more preferable especially 0.5 to 8 g / 10 min, and especially 1 to 6 g / 10 min.

  If the vinyl acetate unit content is 5% by mass or more, the resulting film is soft and not only can maintain flexibility and elastic recovery, but also can impart surface tackiness. On the other hand, if it is 25 mass% or less, surface tackiness will not be too strong and unwinding property and an external appearance can be maintained favorable. Moreover, if the melt flow rate is 0.2 g / 10 min or more, the extrudability can be maintained satisfactorily, while if it is 10 g / 10 min or less, the film forming stability can be maintained, This is preferable because it is possible to suppress the occurrence of thickness unevenness and variations in mechanical strength.

<Other ingredients>
In any of the layers constituting the stretch packaging film of the present invention, various additives such as the following may be appropriately blended in order to impart performance such as antifogging property, antistatic property, slipperiness and adhesiveness. Can do.

  Here, as various additives, for example, an aliphatic alcohol system which is a compound of a fatty acid alcohol having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, and a fatty acid having 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms. Fatty acid esters, specifically, monoglycerylate, polyglycerin oleate, glycerin triricinoleate, glycerin acetylricinoleate, polyglycerin stearate, glycerin laurate, polyglycerin laurate, methylacetylricinoleate, ethylacetylricinoleate, Butylacetylricinoleate, propylene glycol oleate, propylene glycol laurate, pentaerythritol oleate, polyethylene glycol oleate, polypropylene glycol oleate, sorbitan oleate, sorbitan laurate, Reethylene glycol sorbitan oleate, polyethylene glycol sorbitan laurate, and the like, and polyalkyl ether polyols, specifically, polyethylene glycol, polypropylene glycol, and the like, and paraffinic oils can be mentioned, one or two of these The above can be used together.

  These additives are preferably blended in an amount of 0.1 to 12 parts by weight, preferably 1 to 8 parts by weight with respect to 100 parts by weight of the resin component constituting the surface layer and / or the intermediate layer.

<Other layers>
The stretch wrapping film of the present invention comprises a laminated film composed of at least two layers having a layer made of a predetermined thermoplastic resin composition as an intermediate layer and having a surface layer containing an olefinic resin on at least one surface. However, within the range not exceeding the gist of the present invention, other layers (hereinafter may be abbreviated as P layer) are introduced as needed, such as improvement of mechanical properties and interlayer adhesion. Also good. Here, the surface layer (hereinafter sometimes abbreviated as S layer) may have the same layer other than both surface layers, that is, an intermediate layer. Further, the intermediate layer (hereinafter sometimes abbreviated as “M layer”) may have at least one layer between both surface layers, and may have two or more layers. For example, a three-layer structure composed of (S layer) / (M layer) / (S layer), a four-layer structure composed of (S layer) / (P layer) / (M layer) / (S layer), (S layer) 5 layers consisting of / (P layer) / (M layer) / (P layer) / (S layer), (S layer) / (M layer) / (P layer) / (M layer) / (S layer) A typical configuration can be given. In this case, the resin composition and thickness ratio of each layer may be the same or different. The stretch wrapping film may form a surface layer only on one side of the layer made of the thermoplastic resin composition. That is, for example, a two-layer structure of (S layer) / (M layer) may be used. Further, another layer may be provided between the surface layer and the intermediate layer.

  In the stretch packaging film of the present invention, the preferred range of the thickness ratio of the surface layer and the intermediate layer to the entire film is 10 to 65% of the front and back layers (the total of the two surface layers if there are two surface layers). The intermediate layer is preferably 90 to 35%. If the thickness ratio is within such a range, stable film-forming stability can be obtained, and suitable surface tackiness can be imparted to the stretch packaging film.

  Furthermore, when considering the stable film-forming processability, surface adhesiveness, various physical properties as a film for stretch packaging, and economic efficiency, the preferred range of the thickness ratio of the surface layer (front and back layers) and the intermediate layer to the entire film is: More preferably, the front and back layers are 20 to 60% and the intermediate layer is 80 to 40%.

  The thickness of the stretch wrapping film of the present invention may be in the range used as a normal stretch wrapping film, that is, in the range of about 8 μm to 30 μm, typically about 9 μm to 20 μm.

  The stretch packaging film of the present invention can be produced, for example, by melt-extruding a material from an extruder and forming the film into a film by inflation molding or T-die molding. When making a laminated film, it is preferable to co-extrusion with a multilayer die using a plurality of extruders. Practically, it is preferable to melt-extrude the material resin from an annular die and perform inflation molding, and the blow-up ratio (tube diameter / die diameter) at that time is preferably 3 or more, particularly preferably in the range of 4 to 7. . As a cooling method in that case, either a method of cooling from the outer surface of the tube, or a method of cooling from both the outer surface and the inner surface of the tube may be used.

  Further, the obtained film is heated to a temperature lower than the crystallization temperature of the resin, and stretched by about 1.2 to 5 times in the longitudinal direction of the film by utilizing a speed difference between nip rolls, or 1.2 in the longitudinal and lateral directions of the film. It may be biaxially stretched to about 5 times. Thereby, improvement of cut property, provision of heat shrinkability, etc. can be performed.

  The storage elastic modulus of the stretch packaging film of the present invention is the loss tangent (tan δ) at −30 ° C. measured at a vibration frequency of 10 Hz and a strain of 0.1% by the dynamic viscoelasticity measurement method described in JIS K-7198A. 0.07 or more. Preferably it is 0.075 or more, More preferably, it is 0.08 or more. When the loss tangent (tan δ) is 0.07 or more, the stress relaxation property at low temperature is increased, and the stress applied to the film during loading during freezing and the volume of the contents packed by the film are reduced. It is possible to prevent the occurrence of wrinkles caused by the cause of The upper limit of the loss tangent (tan δ) is not particularly specified, but is preferably 0.5 or less. If it is 0.5 or less, the viscosity of the film at low temperature becomes small, and it becomes difficult to cause a problem that the tray and the film stick to each other even when loaded at the time of freezing or the like, which is advantageous as a film for stretch packaging. Each of the above physical properties is appropriately determined by blending the thermoplastic resin composition (A) component, the thermoplastic resin composition (B) component, the thermoplastic resin composition (C) component, and the thermoplastic resin composition (D) component. This can be achieved by adjusting, and in particular, it can be achieved by setting the blending ratio of the thermoplastic resin composition (B) component to 10 to 50% by mass.

  The storage elastic modulus of the film for stretch packaging of the present invention is the storage elastic modulus (E ′) at 20 ° C. measured at a vibration frequency of 10 Hz and a strain of 0.1% by the dynamic viscoelasticity measurement method described in JIS K-7198A. Is preferably in the range of 100 MPa to 1 GPa. When the film is used as a soft film, the value of the elastic modulus near room temperature is an index. When the storage elastic modulus (E ′) at 20 ° C. is 100 MPa or more, problems such as poor film workability due to close contact between the films at room temperature are unlikely to occur. On the other hand, if it is 1 GPa or less, the film does not become too hard and is appropriately stretched, which is advantageous for soft film applications. Each of the above physical properties is achieved by appropriately adjusting the blending ratio of the resin (A), resin (B), resin (C), and resin (D) used in the intermediate layer, particularly the blending ratio of the resin (C). Can be achieved by adjusting the content to 10 to 40% by mass.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In addition, the various measured value and evaluation about the film displayed in this specification and its material were performed as follows. Here, the flow direction of the film from the extruder is called the vertical direction, and the perpendicular direction is called the horizontal direction.

(1) Melt viscosity (η)
A nozzle (diameter 1 mm, length 10 mm) was attached to Shimadzu Corporation Koka-type flow tester CFT-500C, and the sample was preheated at 200 ° C. for 5 minutes, and then the shear rate dependence of melt viscosity was measured. A power approximation curve of a scatter diagram of the apparent viscosity (Pa · s) with respect to the shear rate was taken, and the apparent viscosity (Pa · s) at a shear rate of 100 sec ⁻¹ was determined and used as the melt viscosity.

(2) Crystallization peak temperature (Tc) and crystallization heat (ΔHc)
Using DSC-7 manufactured by PerkinElmer, Inc., according to JISK7121, JISK7122, the measurement sample was heated to 200 ° C at a temperature increase rate of 10 ° C / min, held for 1 minute, and then the temperature decrease rate was 10 ° C / min. The crystallization peak temperature (Tc) and the crystallization heat amount (ΔHc) were determined based on the obtained crystallization curve.

(3) Loss tangent at -30 ° C. (tan δ)
According to the dynamic viscoelasticity measurement method described in the JISK-7198A method, using a dynamic viscoelasticity measurement device “DVA-200” manufactured by IT Measurement Control Co., Ltd., the vibration frequency is 10 Hz in the transverse direction (TD). Measurement was performed from −100 ° C. to 200 ° C. at a rate of temperature increase of 1 ° C./min at a strain of 0.1%, and the loss tangent (tan δ) at a temperature of −30 ° C. was determined from the obtained data.

(4) Storage elastic modulus at 20 ° C. (E ′)
According to the dynamic viscoelasticity measurement method described in the JISK-7198A method, using a dynamic viscoelasticity measurement device “DVA-200” manufactured by IT Measurement Control Co., Ltd., the vibration frequency is 10 Hz in the transverse direction (TD). Measurement was performed from −100 ° C. to 200 ° C. at a rate of temperature increase of 1 ° C./min at a strain of 0.1%, and the storage elastic modulus (E ′) at a temperature of 20 ° C. was determined from the obtained data.

(5) Tensile breaking elongation at −40 ° C. Using an Intesco tensile tester equipped with a constant temperature and humidity chamber PL-2KH manufactured by Espec, in accordance with JISK7127, a test temperature of −40 ° C., a test speed of 500 mm / min. The film was measured at n = 5 in the machine direction (MD) and the transverse direction (TD), and the average value was defined as the tensile elongation at break.

(6) Impact resistance at low temperature 200 g of water is placed in a foamed styrene tray (length 200, width 200 mm, height 30 mm), and this tray is automatically weighed and packaged with a pricing machine (AW-4600 manufactured by Teraoka Seiko Co., Ltd.) ) With a film having a width of 400 mm obtained in Examples and Comparative Examples. After stacking the packaged product in five stages, it was stored in an environmental test machine at -25 ° C. for 24 hours, dropped horizontally from a height of 1 m onto the concrete floor, and the number of film breaks was confirmed. This operation was repeated twice, the average number of fractures was determined, and the impact resistance at low temperatures was evaluated according to the criteria shown in Table 2. Here, in Table 2, the evaluation Δ or higher is within a range where there is no practical problem.

(7) Packing machine suitability Using the 400 mm wide film obtained in the examples and comparative examples, the expanded polystyrene tray (length 330 mm, width 230 mm, height 38 mm) is packaged by a linear overlap shrink automatic packaging machine. Based on the criteria shown in Table 2, transparency, cut property, packaging wrinkle, bottom folding stability and tearability after packing were evaluated, and Table 1 shows the results. Here, in Table 1, the evaluation “◯” or more is within a practically acceptable range.

(8) Productivity For Examples and Comparative Examples, productivity was evaluated for Examples that were evaluated as having no practical problems with respect to impact resistance at low temperatures and suitability for packaging machines according to the criteria shown in Table 2. In order to reduce the material cost, the trimming loss is added as a recycled component so that the surface layer component is 10 parts by weight with respect to the intermediate layer and melted in the same manner as when the recycled component is not added. Molded to obtain a three-layer film.

<Example 1>
About the resin composition which forms both surface layers, ethylene-vinyl acetate copolymer (vinyl acetate content: 15 mass%, melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18 N) as an ethylene polymer. ) 2.3 g / 10 min) 97 parts by mass and 3 parts by mass of diglycerin oleate as an antifogging agent were melt-kneaded. On the other hand, about the resin composition which forms an intermediate | middle layer, the propylene-type resin (Propylene-ethylene random copolymer, crystallization calorie | heat amount: 80.9J / g, crystallization peak temperature: 100.5 degreeC which is (A) component , Melt flow rate (JISK7210, temperature: 230 ° C., load: 21.18 N) 3.0 g / 10 min), and ethylene-α-olefin block copolymer (density (JISK7112) as an ethylene-based resin as component (B)) 0.877 (g / cm ³ ), melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18 N) 0.5 g / 10 min), vinyl aromatic compound as component (C) and conjugated diene Or a hydrogenated derivative thereof (melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18 Nkgf ) 0.5 g / 10 min) and hydrogenated petroleum resin (softening temperature 125 ° C., Arakawa Chemical Industries, Ltd., Alcon P125) as component (D) by mass ratio (A) / (B) / ( C) / (D) = 25/35/15/25 blended, these were melt-kneaded, and these melt-kneaded resins were coextruded with a circular three-layer die at 190 ° C. and a blow-up ratio of 5.0. Molding was performed to obtain a three-layer film having a total thickness of 11 μm (2.2 μm / 6.6 μm / 2.2 μm).

<Example 2>
Except for changing the resin composition of the intermediate layer in Example 1 to (A) / (B) / (C) / (D) = 20/40/15/25 by mass ratio, the same as Example 1 A three-layer film was obtained.

<Example 3>
Except for changing the resin composition of the intermediate layer in Example 1 to (A) / (B) / (C) / (D) = 30/30/15/25 by mass ratio, the same as Example 1 A three-layer film was obtained.

<Example 4>
An ethylene-α olefin block copolymer (density (JISK7112) 0.887 (g / cm ³ )), melt flow rate (JISK7210, temperature) using (B) component of the resin composition of the intermediate layer in Example 1 as an ethylene-based resin. : 190 ° C., load: 21.18 N) 5.0 g / 10 min) and mass ratio changed to (A) / (B) / (C) / (D) = 30/30/15/25 A three-layer film was obtained in the same manner as in Example 1 except that.

<Comparative Example 1>
The propylene-based resin which is the component (A) of the intermediate layer in Example 1 is a propylene-ethylene random copolymer (1) as component (A) -1 (crystallization heat amount: 62.5 J / g, crystallization peak temperature) : 112.3 ° C., melt flow rate (JISK7210, temperature: 230 ° C., load: 21.18 N) 2.8 g / 10 min), and propylene-ethylene random copolymer (2) as (A) -2 component ( Amount of crystallization: 4.9 J / g, crystallization peak temperature: 97.2 ° C., melt flow rate (JISK7210, temperature: 230 ° C., load: 21.18 N) 2 g / 10 min) (A) -1 / (A) -2 = 40/15 kneaded and a block copolymer of vinyl aromatic compound and conjugated diene as component (C) or a hydrogenated derivative thereof (melt flow (JISK7210, temperature: 190 ° C., load: 21.18 Nkgf) 0.5 g / 10 min) and hydrogenated petroleum resin (softening temperature 125 ° C., Arakawa Chemical Industries, Alcon P125) as component (D) Was blended as (A) / (C) / (D) = 55/20/25 by mass ratio, and a three-layer film was obtained in the same manner as in Example 1 except that these were melt-kneaded.

<Comparative Example 2>
About the resin composition which forms both surface layers, ethylene-vinyl acetate copolymer (vinyl acetate content: 15 mass%, melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18 N) as an ethylene polymer. ) 2.3 g / 10 min) 97 parts by mass and 3 parts by mass of diglycerin oleate as an antifogging agent were melt-kneaded. On the other hand, for the resin composition forming the intermediate layer, linear low-density polyethylene (LLDPE) (crystallization calorific value: 108.4 J / g, crystallization peak temperature: 106.3 ° C., density (JIS K7112), melt The flow rate (JISK7210, temperature: 230 ° C, load: 21.18N) 2g / 10min) is melt-kneaded, and these melt-kneaded resins are co-extruded inflation molding at an annular three-layer die of 190 ° C and a blow-up ratio of 5.0. Thus, a three-layer film having a total thickness of 13.5 μm (3.5 μm / 6.5 μm / 3.5 μm) was obtained.

<Comparative Example 3>
About the resin composition which forms both surface layers, ethylene-vinyl acetate copolymer (vinyl acetate content: 15 mass%, melt flow rate (JISK7210, temperature: 190 ° C., load: 21.18 N) as an ethylene polymer. ) 2.3 g / 10 min) 97 parts by mass and 3 parts by mass of diglycerin oleate as an antifogging agent were melt-kneaded. On the other hand, about the resin composition which forms an intermediate | middle layer, (A) component propylene-type resin (Block polypropylene, crystallization calorie | heat amount: 67.0J / g, crystallization peak temperature: 121.0 degreeC, melt flow rate ( JISK7210, temperature: 230 ° C., load: 21.18 N) 2.0 g / 10 min), and a block copolymer of a vinyl aromatic compound and isobutylene as component (C) (melt flow rate (JISK7210, temperature: 230 ° C., load: 21.18 N) 6.0 g / 10 min), and hydrogenated petroleum resin (softening temperature 125 ° C., Arakawa Chemical Industries, Ltd., Alcon P125) as a component (D) by mass ratio ( A) / (C) / (D) = 45/30/25 were blended, these were melt-kneaded, and these melt-kneaded resins were blown up at an annular three-layer die 190 ° C. By co-extrusion inflation molding at 5.0 to obtain a three-layer film having a total thickness of 11μm (2.2μm / 6.6μm / 2.2μm).

The measurement results of the examples are shown in Table 1 below. Table 2 shows the evaluation criteria for evaluating the impact resistance and the suitability of the packaging machine of the obtained film at a low temperature.

From the result of Table 1, since Examples 1-4 contain the thermoplastic resin composition (A) component-(D) component in an intermediate | middle layer, it was excellent in the impact resistance in low temperature, and measured with the vibration frequency of 10 Hz. Since the storage elastic modulus (E ′) at 20 ° C. is 100 MPa to 1 GPa, it can be confirmed that good results are also obtained for the packaging machine suitability.
Moreover, Example 2 is excellent in impact resistance at lower temperatures by containing 40% by mass of the thermoplastic resin composition (B) component in the thermoplastic resin composition forming the intermediate layer, and is a preferred embodiment. is there.
Moreover, as shown in Examples 1-4, productivity evaluation is also favorable.
On the other hand, in Comparative Example 1, the thermoplastic resin composition (B) component is not included in the intermediate layer, so the impact resistance at low temperatures is poor. In Comparative Examples 2 and 3, the thermoplastic resin composition (A ) Component and thermoplastic resin composition (B) component were not added, and it was found that wrinkles were generated on the film surface in suitability for packaging machines, and the film did not overlap and could not be folded neatly .

  The stretch packaging film of the present invention can be suitably used as a stretch packaging film for food packaging, for example.

Claims (9)

Storage elasticity at 20 ° C. measured at a vibration frequency of 10 Hz by a dynamic viscoelasticity measurement method having at least one layer composed of a thermoplastic resin composition comprising the following components (A) and (B) as essential components A film for stretch packaging having a rate (E ′) of 100 MPa to 1 GPa.
(A) Propylene-ethylene copolymer, propylene-α-olefin copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-α-olefin copolymer, block polypropylene, homopropylene Component (B) composed of at least one resin selected from the group consisting of ethylene-α-olefin block copolymer and ethylene-α-olefin random copolymer   The film for stretch packaging according to claim 1, wherein a loss tangent (tan δ) at -30 ° C measured by a dynamic viscoelasticity measurement method at a vibration frequency of 10 Hz is 0.07 or more. The ratio η (A) / η (B) of the melt viscosity η (A) of the component (A) and the melt viscosity η (B) of the component (B) under the conditions of a temperature of 200 ° C. and a shear rate of 100 sec ⁻¹ The film for stretch packaging according to claim 1 or 2, wherein the film is 0.10 or more and 0.95 or less, or the ratio η (B) / η (A) is 0.10 or more and 0.95 or less. In the layer made of the thermoplastic resin composition, the total amount of the component (A) and the component (B) is 50% or more and 100% or less of the total amount,
The film for stretch packaging according to any one of claims 1 to 3, wherein a mass ratio of the component (A) / the component (B) is 0.5 or more and 2.0 or less. The film for stretch packaging according to any one of claims 1 to 4, wherein the layer made of the thermoplastic resin composition includes the following component (C).
(C) A component comprising a copolymer of a vinyl aromatic compound and a conjugated diene or a hydrogenated derivative thereof. The stretch packaging film according to any one of claims 1 to 5, wherein the layer made of the thermoplastic resin composition includes the following component (D).
(D) At least one component selected from petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof.   The film for stretch packaging according to any one of claims 1 to 6, wherein the layer made of the thermoplastic resin composition contains an ethylene-vinyl acetate copolymer.   The layer made of the thermoplastic resin composition is an intermediate layer, and has at least two layers having a surface layer containing an olefin resin on at least one surface, according to any one of claims 1 to 7. The film for stretch packaging as described. The film for stretch packaging according to claim 8, wherein the olefin-based resin is an ethylene-based resin having the following characteristics (1) and (2).
(1) Ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 5 to 25% by mass (2) Melt flow rate (JIS K 7210, 190 ° C., load 21.18 N) is 0.2 to 10 g / 10 minutes