JP2018167880A - Bubble cushioning member having easy tearing property - Google Patents

Abstract

To provide a bubble cushioning member having easy tearing property in which tearing is easy and which is able to be cut easily and straight even by hands of a person.SOLUTION: A bubble cushioning member having easy tearing property has a cell layer film (II) in which a plurality of protrusions are formed, a backing film (I) which is layered on the bottom face side of the cell layer film (II), and a top film (III) which is layered on the top side of the cell layer film (II), which is characterized in that the backing film (I) is a film made of a polyethylene resin composition, the cell layer film (II) is a film made of the polyethylene resin composition, and the top film (III) is a film made of mixed resin including the polyethylene resin composition and cyclic olefin resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an easily tearable bubble cushioning material that is easy to tear and can be easily cut linearly by a human hand.

  Bubble cushioning materials, that is, those obtained by laminating and laminating a back film on the bottom side of a cell layer film on which many protrusions are formed by thermoforming, particularly vacuum forming of a plastic film, or the top of the cell layer film. On the side, another flat top film laminated is used for buffer packaging and other wide applications. Some of them also have a lower film laminated on the bottom side of the cell layer film.

The bubble cushioning material is usually provided in the form of a coil obtained by winding a long product.
In use, the bubble cushioning material is usually drawn out from this winding and supplied to an apparatus for punching or folding.

  On the other hand, in the case of cushioning packaging for moving luggage, indoor remodeling including moving, curing for construction, etc., cut out as much as necessary with scissors or a cutter knife while rolling up the bubble cushioning material. In this cutting operation, there is an unexpected danger unless care is taken in handling the cutter knife.

  In the usage mode in which the foam cushioning material is cut off from the winding as much as necessary, as long as the premise that the cushioning performance of the foam sheet is not impaired is torn by hand in the width direction, that is, the direction perpendicular to the longitudinal direction. It is convenient if you can.

However, the bubble cushioning material currently manufactured and sold is resistant to tearing in the width direction by hand, and is not very tearable by hand. The material of the bubble cushioning material is polyethylene in many cases, and the manufacturing method is to form a plastic film melt-extruded from a T-die with a thermoforming roll to form the cell layer film, and then melt-extrude it from another T-die. It is manufactured by continuously performing an operation of fusing the back film.
The polyethylene extruded from the T-die is uniaxially stretched in the extrusion direction to some extent, and can be torn to some extent in the direction along the flow, but is difficult to tear in the width direction.

  In order to improve such a defect, for example, a flat plastic back film is bonded to the bottom surface of a cap film (cell layer film) in which a large number of caps are formed by thermoforming a plastic film. In a long plastic bubble sheet having a three-layer structure formed by joining the top and another flat plastic liner film (top film), at least one of the cap film, the back film, and the liner film In addition, the bottom surface of the cap of a plastic bubble sheet that is easy to tear using a film that is easy to tear along a line perpendicular to the longitudinal direction, or a cap film (cell layer film) that is formed by thermoforming a plastic film. Flat In a long plastic bubble sheet having a two-layer structure formed by laminating a back film made of a plastic, a film that is easy to tear along a line perpendicular to the longitudinal direction was used for at least one of the cap film and the back film. A plastic bubble sheet that is easy to tear has been proposed (see Patent Document 1).

  In addition, an adhesive layer is disposed on at least a part of one side of a cellular cushion sheet formed by bonding a cap film (cell layer film) having a number of closed cells to one side of a base film (back film). A self-adhesive cellular cushion sheet, wherein the base film is composed of a thermoplastic film that can be laterally split in the width direction, and one side of the base film (back film) A self-adhesive cellular cushion sheet in which an adhesive layer is disposed on at least a part of one side of a cellular cushion sheet obtained by laminating a cap film (cell layer film) having a large number of closed cells. A self-adhesive cellularity in which a thermoplastic film that can be laterally split in the width direction, that is, the direction perpendicular to the longitudinal direction, is laminated on the base film. Opposition sheet has been proposed (see Patent Document 2).

  In addition, it is a member formed by heat-sealing a cap film in which a large number of cells are formed on one side of the base-side film, and the base-side film itself is blown at a blow ratio of 4 or higher. A buffer sheet that is easily cracked and formed of a density polyethylene resin film has been proposed (see Patent Document 3).

  Furthermore, a buffer sheet that is easy to tear laterally by using a cyclic olefin-based resin in at least one layer of the film constituting the bubble buffer material has been proposed. For example, a cell layer film in which a plurality of protrusions are formed, a back film laminated on the bottom side of the cell layer film, and optionally a lower film laminated on the back film and a top film laminated on the top side of the cell layer film An easily tearable foam cushioning material comprising: at least one of a back film, a cell layer film, a lower film and a top film containing a polyolefin resin layer, a cyclic olefin resin and a polyolefin resin By including a laminate formed by laminating a resin layer and a polyolefin-based resin layer in this order, an easily tearable bubble cushioning material having good tearability in the longitudinal direction and the direction perpendicular to the longitudinal direction has been proposed ( (See Patent Document 4)

Also,

JP 2004-74725 A JP 2005-59357 A Japanese Patent No. 389976 Japanese Patent Laying-Open No. 2015-208912

However, the bubble sheet and the self-adhesive foam cushion sheet disclosed in Patent Documents 1, 2, and 3 are films that use an ionomer resin as a film that is easy to tear in a direction perpendicular to the longitudinal direction, A high-density polyethylene film with an increased blow ratio and a film made of inflation-formed low-density polyethylene are used, and although a bubble cushioning material that can be torn by hand in a direction perpendicular to the longitudinal direction is obtained, the longitudinal direction In addition, there is a problem of feeling heavy when tearing in a direction perpendicular to the longitudinal direction. Further, since tearing cannot be performed with a certain degree of directionality, further improvement in tearability has been demanded.
Further, the easily tearable bubble cushion disclosed in the above-mentioned document 4 can be easily torn with a certain degree of direction in the longitudinal direction and the direction perpendicular to the longitudinal direction, but the back film, the cell layer film, Since at least one of the lower film and the top film is required to be a laminated film having a three-layer structure, the film structure as the entire foam cushioning material becomes complicated and lacks versatility.

  The present invention has been made in view of the above-mentioned problems of the prior art, and provides an easily tearable bubble cushioning material that has good tearability in the longitudinal direction and a direction perpendicular to the longitudinal direction and can be easily torn by hand. .

  As a result of intensive studies to solve the above problems, the present inventors have a cell layer film, a back film laminated on the bottom surface side of the cell layer film, and a top film laminated on the top side of the cell layer film. In the buffer material formed, it was found that the above problem can be solved by using a film made of a mixed resin containing a polyethylene-based resin composition and a cyclic olefin-based resin for the top film, and based on these findings Further studies have been made and the present invention has been completed.

  That is, according to the first invention of the present invention, the cell layer film (II) having a plurality of protrusions formed thereon, the back film (I) laminated on the bottom surface side of the cell layer film (II), An easily tearable foam cushioning material comprising a top film (III) laminated on the top side of a cell layer film (II), wherein the back film (I) comprises a polyethylene resin composition (A1). A cell layer film (II) comprising a polyethylene resin composition (A2), and the top film (III) comprising a polyethylene resin composition (B) and a cyclic olefin resin (c). An easily tearable foam cushioning material characterized by being a film made of a mixed resin is provided.

Further, according to the second invention of the present invention, in the first invention, the polyethylene resin compositions (A1) and (A2) are composed of the following composition (A) and are easy to tear. A bubble cushioning material is provided.
Composition (A): 35 to 65% by weight of the following component (a1), 0 to 30% by weight of the following component (a2) and 20 to 65% by weight of the following component (a3) [However, (a1), (a2 ) And (a3) is 100% by weight. ] The composition containing this.
Component (a1): Density 0.910 to 0.940 (g / cm ³ ), MFR 0.1 to 10 (g / 10 min) ethylene / α-olefin copolymer Component (a2): Density 0.940 -0.970 (g / cm ³ ), high density polyethylene with MFR 0.1-10 (g / 10 min) Component (a3): high pressure method low density polyethylene with MFR 0.1-10 (g / 10 min)

According to the third invention of the present invention, in the first or second invention, the polyethylene resin composition (B) has a density of 0.900 to 0.940 (g / cm ³ ), MFR 0.1 to An easily tearable foam cushioning material comprising a high-pressure low-density polyethylene (b1) of 15 (g / 10 min) is provided.

  According to a fourth aspect of the present invention, in the third aspect, the top film (III) comprises 40 to 90% by weight of the high pressure method low density polyethylene (b1) and the cyclic olefin resin (c) 10 to 60. An easily tearable foam cushioning material characterized by comprising% by weight is provided.

According to the fifth aspect of the present invention, in the first or second aspect, the polyethylene resin composition (B) has a density of 0.900 to 0.940 (g / cm ³ ), MFR 0.1 to An easily tearable foam cushioning material comprising an ethylene / α-olefin copolymer (b2) of 10 (g / 10 minutes) is provided.

  According to a sixth invention of the present invention, in the fifth invention, the top film (III) comprises 40 to 90% by weight of the ethylene / α-olefin copolymer (b2) and the cyclic olefin resin (c). An easily tearable foam cushioning material comprising 10 to 60% by weight is provided.

According to the seventh invention of the present invention, in the first or second invention, the polyethylene-based resin composition (B) has a density of 0.900 to 0.940 (g / cm ³ ), MFR 0.1 to 10 (g / 10 min) of ethylene / α-olefin copolymer (b2) 20 to 70% by weight, density 0.900 to 0.940 (g / cm ³ ), MFR 0.1 to 15 (g / An easily tearable foam cushioning material comprising 30 to 80% by weight of a high-pressure low-density polyethylene (b1) that is 10 minutes) is provided.

  According to an eighth aspect of the present invention, in the seventh aspect, the top film (III) comprises 40 to 90% by weight of the polyethylene resin composition (B) and the cyclic olefin resin (c) 10 to 60. An easily tearable foam cushioning material characterized by comprising% by weight is provided.

  According to a ninth invention of the present invention, the easily tearable bubble buffering material according to any one of the first to eighth inventions, wherein the cyclic olefin resin (c) is an ethylene / cyclic olefin copolymer. Is provided.

  According to a tenth aspect of the present invention, there is provided the easily tearable foam cushioning material according to the ninth aspect, wherein the ethylene / cyclic olefin copolymer has a glass transition point of 60 ° C. or higher. .

  The easily tearable bubble cushioning material of the present invention has good tearability in the longitudinal direction and the direction perpendicular to the longitudinal direction, and can be easily and manually torn.

FIG. 1 is a schematic view showing a cross section of the easily tearable foam cushioning material of the present invention. FIG. 1 shows an example in which a lower film (IV) is added.

The easily tearable foam cushioning material of the present invention comprises a cell layer film (II) having a plurality of protrusions formed thereon, a back film (I) laminated on the bottom side of the cell layer film (II), and a cell layer film ( II) an easily tearable foam cushioning material having a top film (III) laminated on the top side, wherein the back film (I) is a film made of the polyethylene resin composition (A1), The layer film (II) is a film made of a polyethylene resin composition (A2), and the top film (III) is a film made of a mixed resin containing a polyethylene resin composition (B) and a cyclic olefin resin (c). It is characterized by being.
Hereinafter, the present invention will be described in detail for each item.

1. Polyethylene resin compositions (A1) and (A2)
The polyethylene resin compositions (A1) and (A2) of the present invention are characterized by comprising a composition (A) containing a component (a1), a component (a2), and a component (a3). Moreover, if the polyethylene-type resin composition (A1) and (A2) are in the range of the composition (A) mentioned later, the component (a1), the component (a2), the component ( The content ratio of a3) may be the same or different.

(1) Component (a1): Ethylene / α-olefin copolymer The component (a1) contained in the composition (A) is a copolymer of ethylene and α-olefin, comprising a metallocene catalyst, a Ziegler catalyst, Any of those polymerized by a Phillips catalyst or the like may be used, and linear low density polyethylene (LLDPE) is preferable. The density is 0.910 to 0.940 g / cm ³ , preferably 0.910 to 0.935 g / cm ³ . When the density is less than 0.910 g / cm ³ , sufficient rigidity cannot be obtained, and the polyethylene resin film made of the composition (A) may be blocked, resulting in poor workability. On the other hand, when the density exceeds 0.940 g / cm ³ , the rigidity of the polyethylene resin film made of the composition (D) is increased, and the handleability may be inferior.
In the present invention, the density is a value measured based on JIS K 6922-2.

The melt flow rate (MFR) of the component (a1) is preferably 0.1 to 10 g / 10 minutes at 190 ° C., more preferably 0.5 to 4.0 g / 10 minutes. If the MFR is less than 0.1 g / 10 min, the melt flowability is poor, film processing becomes difficult, and problems such as increased motor load may occur, which is not preferable. On the other hand, if it exceeds 10 g / 10 min, the melt viscosity is too low and the film-forming stability during film processing of the composition (A) may be lowered, which is not preferable.
In the present invention, the melt flow rate (MFR) is a melt flow rate value measured according to JIS-K-7210.

  Specifically, the component (a1) used in the present invention is as follows. That is, the α-olefin copolymerized with ethylene is copolymerized in an amount of 0.1 to 15 mol%, preferably 0.5 to 10 mol%, particularly preferably 0.5 to 5 mol%. The α-olefin is usually an α-olefin having 3 to 8 carbon atoms, specifically, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, 4-methylpentene-1 can be mentioned.

(2) Component (a2): High-density polyethylene The component (a2) contained in the composition (A) is high-density polyethylene (HDPE), even if it is a copolymer of ethylene and an α-olefin. May be any of those polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. The density is from 0.940 to 0.970 g / cm ³ , preferably from 0.950 to 0.960 g / cm ³ . When the density is less than 0.940 g / cm ³ , sufficient rigidity cannot be obtained, and the polyethylene resin film made of the composition (A) may be blocked, resulting in poor workability. On the other hand, when the density exceeds 0.970 g / cm ³ , the rigidity of the polyethylene resin film made of the composition (A) is increased, and the handling property may be inferior.
In the present invention, the density is a value measured based on JIS K 6922-2.

Moreover, it is preferable that the melt flow rate (MFR) of a component (a2) is 0.1-10 g / 10min in 190 degreeC. More preferably, it is 0.5-4.0 g / 10min. If the MFR is less than 0.1 g / 10 min, the melt flowability is poor, film processing becomes difficult, and the motor load may increase, which is not preferable. On the other hand, if it exceeds 10 g / 10 min, the melt viscosity is too low and the film-forming stability during film processing of the composition (A) may be lowered, which is not preferable.
From the viewpoint of dispersibility, the melt flow rate (MFR) of the high-density polyethylene (a2) is preferably higher than the melt flow rate (MFR) of the ethylene / α-olefin copolymer (a1).
In the present invention, the melt flow rate (MFR) is a melt flow rate value measured according to JIS-K-7210.

Specifically, the component (a2) used in the present invention is as follows. That is, the ethylene homopolymer or the α-olefin copolymerized with ethylene is in an amount of 0.1 to 15 mol%, preferably 0.5 to 10 mol%, particularly preferably 0.5 to 5 mol%. The type of α-olefin is usually an α-olefin having 3 to 8 carbon atoms, specifically, propylene, butene-1, pentene-1, hexene-1, heptene. -1, Octene-1, 4-methylpentene-1.

(3) Component (a3): High-pressure method low-density polyethylene Component (a3) used in the present invention is high-pressure method low-density polyethylene (LDPE), which is polymerized with an organic peroxide and contains ethylene alone. Either a polymer or a copolymer of ethylene and a comonomer may be used. Examples of the copolymer of ethylene and comonomer include, for example, an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer (EMA), and an ethylene-ethyl acrylate copolymer. Examples thereof include a polymer (EEA), an ethylene-acrylic acid copolymer (EAA), and an ethylene-acrylic acid / maleic anhydride copolymer.
The density is preferably selected from the range of 0.915 to 0.935 g / cm ³ , more preferably 0.920 to 0.933 g / cm ³ . More preferably, it is 0.922-0.931 g / cm < ³ >. When a high-pressure method low-density polyethylene having a density of less than 0.915 g / cm ³ is used, perforation is likely to occur when a polyethylene film comprising the composition (A) is formed, and a film having a good appearance may not be obtained. is there. On the other hand, when the density exceeds 0.935 g / cm ³ , processing stability may not be obtained when a polyethylene film formed from the composition (A) is formed.
In the present invention, the density is a value measured based on JIS K 6922-2.
It is preferable that MFR of a component (a3) is 0.1-10 (g / 10min) in 190 degreeC.

(4) Composition (A)
In the present invention, the composition (A) preferably contains 35 to 65% by weight of component (a1), 0 to 30% by weight of component (a2) and 20 to 65% by weight of component (a3). However, the total amount of (d1), (a2) and (a3) is 100% by weight.

  In the present invention, the composition (A) includes an antifogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, an ultraviolet absorber, a colorant and the like. Ingredients can be added as long as the object of the present invention is not impaired.

  When the composition (A) used in the present invention is obtained by mixing, each polymer is mixed by various known methods such as a Henschel mixer, a V blender, a ribbon blender, a tumbler mixer, or the like. A method of granulation or pulverization after melt-kneading with a single screw extruder, twin screw extruder, kneader, Banbury mixer or the like can be employed.

2. Polyethylene resin composition (B)
The polyethylene-based resin composition (B) of the present invention has a density of 0.900 to 0.940 (g / cm ³ ) and a high pressure method low density polyethylene (b1) having an MFR of 0.1 to 15 (g / 10 min), Alternatively, among ethylene / α-olefin copolymer (b2) having a density of 0.900 to 0.940 (g / cm ³ ) and MFR of 0.1 to 10 (g / 10 minutes), either a single resin or a mixed resin of both. It is characterized by being.

  When the polyethylene resin composition (B) is composed of a mixed resin of the high pressure method low density polyethylene (b1) and the ethylene / α-olefin copolymer (b2), the high pressure method low density polyethylene (b1) is 30. -80% by weight, ethylene / α-olefin copolymer (b2) is preferably 20-70% by weight, more preferably high-pressure low-density polyethylene (b1) is 40-70% by weight, ethylene / α. -Olefin copolymer (b2) is 30 to 60 weight%. When the high-pressure method low-density polyethylene (b1) is less than 30% by weight, the melt tension at the time of melting is lowered, so that there is a possibility that film-forming stability such as generation of neck-in is inferior. On the other hand, when the high-pressure method low-density polyethylene (b1) exceeds 80% by weight, the main component of the polyethylene-based resin composition (B) is the high-pressure method low-density polyethylene (b1). However, the interface strength with the cyclic olefin-based resin (c) is lowered, and the strength of the film itself may be lowered.

(1) High pressure method low density polyethylene (b1)
The high-pressure low-density polyethylene (b1) used in the present invention is polymerized with an organic peroxide and may be either an ethylene homopolymer or a copolymer of ethylene and a comonomer. Examples of the copolymer of ethylene and comonomer include, for example, an ethylene-α-olefin copolymer, an ethylene-vinyl acetate copolymer (EVA), an ethylene-methyl acrylate copolymer (EMA), and an ethylene-ethyl acrylate copolymer. Examples thereof include a polymer (EEA), an ethylene-acrylic acid copolymer (EAA), and an ethylene-acrylic acid / maleic anhydride copolymer.
Density is preferably selected from the range of 0.900~0.940g / cm ^3, more preferably 0.910~0.930g / cm ^3. More preferably, it is 0.915-0.925 g / cm < ³ >. When a high-pressure low-density polyethylene having a density of less than 0.900 g / cm ³ is used, perforation tends to occur when the top film (III) is formed, and a film having a good appearance may not be obtained. On the other hand, when the density exceeds 0.940 g / cm ³ , processing stability may not be obtained at the time of forming the top film (III).
In the present invention, the density is a value measured based on JIS K 6922-2.
Further, the melt flow rate (MFR) of the high-pressure low-density polyethylene (b1) is preferably 0.1 to 15 g / 10 minutes at 190 ° C., more preferably 0.5 to 10 g / 10 minutes.
When the MFR is less than 0.1 g / 10 min, the spreadability of the molten resin is poor, and film cracking may occur during processing of the top film (III). On the other hand, if it exceeds 15 g / 10 minutes, the melt viscosity is too low, and the film-forming stability during processing of the top film (III) may be lowered, which is not preferable.

(2) Ethylene / α-olefin copolymer (b2)
The ethylene / α-olefin copolymer (b2) used in the present invention is a copolymer of ethylene and α-olefin, which is polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. It is preferable that it is a linear low density polyethylene (LLDPE). Density is 0.900~0.940g / cm ^3, preferably 0.910~0.930g / cm ^3. When the density is less than 0.900 g / cm ³ , sufficient rigidity cannot be obtained, and the top film (III) may be blocked, resulting in poor workability. On the other hand, when the density exceeds 0.940 g / cm ³ , the rigidity of the top film (III) is increased and the handling property may be deteriorated.
In the present invention, the density is a value measured based on JIS K 6922-2.

The melt flow rate (MFR) of the ethylene / α-olefin copolymer (b2) is preferably 0.1 to 10 g / 10 min at 190 ° C., more preferably 0.5 to 5.0 g / 10 minutes.
If the MFR is less than 0.1 g / 10 min, the melt flowability is poor, film processing becomes difficult, and the motor load may increase, which is not preferable. On the other hand, if it exceeds 10 g / 10 minutes, the melt viscosity is too low, and film formation stability during processing of the top film (III) may be lowered, which is not preferable.
In the present invention, the melt flow rate (MFR) is a melt flow rate value measured according to JIS-K-7210.

  Specifically, the ethylene / α-olefin copolymer (b2) used in the present invention is as follows. That is, the α-olefin copolymerized with ethylene is copolymerized in an amount of 0.1 to 15 mol%, preferably 0.5 to 10 mol%, particularly preferably 0.5 to 5 mol%. The α-olefin is usually an α-olefin having 3 to 8 carbon atoms, specifically, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, 4-methylpentene-1 can be mentioned.

3. Cyclic olefin resin (c)
Examples of the cyclic olefin resin (c) used in the present invention include a norbornene polymer, a vinyl alicyclic hydrocarbon polymer, and a cyclic conjugated diene polymer. Among these, norbornene-based polymers are preferable. The norbornene polymer includes a ring-opening polymer of a norbornene monomer (hereinafter also referred to as “COP”), a norbornene copolymer obtained by copolymerizing a norbornene monomer and an α-olefin such as ethylene. And the like (hereinafter also referred to as “COC”). COP and COC hydrogenated products can also be used.

As the COC, linear monomers such as α-olefins such as ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1 and octene-1 and cyclic monomers such as tetracyclododecene and norbornene And a cyclic olefin copolymer obtained from the above. More specifically, the above-mentioned linear monomer, monocycloalkene having 3 to 20 carbon atoms, bicyclo [2.2.1] -2-heptene (norbornene), and derivatives thereof, tricyclo [4.3.0.12. , 5] -3-decene and derivatives thereof, tetracyclo [4.4.1.0.2, 5.17,10] -3-dodecene and derivatives thereof, pentacyclo [6.5.1.13, 6.02 , 7.09,13] -4-pentadecene and derivatives thereof, pentacyclo [7.4.0.12,5.19,12.08,13] -3-pentadecene and derivatives thereof, pentacyclo [8.4. .12, 5.19, 12.08, 13] -3-hexadecene and derivatives thereof, pentacyclo [6.6.1.13, 6.02, 7.09,14] -4-hexadecene and derivatives thereof, hexacycline [6.6.1.13, 6.110, 13.02, 7.09,14] -4-heptadecene and its derivatives, heptacyclo [8.7.0.12,9.14,7.111,17 .03, 8.012, 16] -5-eicosene and the like and derivatives thereof, heptacyclo [8.7.0.13, 6.110, 17.112, 15.02, 7.011, 16] -4-eicosene And its derivatives, heptacyclo [8.8.0.12
, 9.14, 7.111, 18.03, 8.012, 17] -5-heneicosene and derivatives thereof, octacyclo [8.8.0.12, 9.14, 7.111, 18.113, 16]. .03, 8.012, 17] -5-docosene and derivatives thereof, nonacyclo [10.9.1.14, 7.113, 20.115, 18.02, 10.03, 8.012, 21.014 , 19] -5-pentacocene and cyclic olefin copolymers composed of copolymers with cyclic olefins such as derivatives thereof. The linear monomer and the cyclic monomer can be used alone or in combination of two or more. Moreover, such a cyclic olefin copolymer can be used individually or in combination. Further, the COP and COC can be used in combination with the cyclic olefin resin (c). In that case, different performances of COP and COC can be imparted.

  In the present invention, the cyclic olefin resin (c) is preferably COC from the viewpoint of dispersibility with respect to polyethylene. The COC is preferably an ethylene / cyclic olefin copolymer in which the linear monomer is ethylene. Furthermore, the cyclic monomer is preferably norbornene or the like.

  In the present invention, the ethylene / cyclic olefin copolymer has an ethylene / cyclic olefin content ratio of 15 to 40/85 to 60 by weight when the total weight of ethylene and cyclic olefin is 100. It is preferably 30 to 40/70 to 60. If the ethylene content is less than 15% by weight, the rigidity becomes too high, and the inflation moldability and bag making suitability are deteriorated. On the other hand, if ethylene is 40% by weight or more, sufficient easy tearability and rigidity cannot be obtained. A content ratio within this range is preferable because the rigidity, tearability, processing stability, and impact strength of the film are improved.

Furthermore, the ethylene / cyclic olefin copolymer preferably has a glass transition point of 60 ° C. or higher. More preferably, it is 70 degreeC or more. When the content of the cyclic olefin is below the above range, the glass transition point becomes below the above range, for example, the barrier property of the fragrance component is lowered, sufficient rigidity cannot be obtained, and high speed packaging machine is suitable. There is a risk of being inferior. On the other hand, when the content of the cyclic olefin exceeds the above range, the glass transition point becomes too high, and the melt moldability of the copolymer and the adhesiveness with the olefin resin may be lowered, which is not preferable.
Further, the weight average molecular weight of the cyclic olefin resin (c) is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

As a commercial product that can be used as the cyclic olefin resin (c), examples of the ring-opening polymer (COP) of a norbornene monomer include “ZEONOR” manufactured by Nippon Zeon Co., Ltd. Examples of the copolymer (COC) include “Appel” manufactured by Mitsui Chemicals, Inc., “TOPAS” manufactured by TICONA, and the like. In the present invention, the TOPAS grade 8007 is preferred because the content ratio of the norbornene-based monomer is in the above-mentioned range and the workability and the like.

4). Easy tear bubble cushioning material The easy tear bubble cushion material of the present invention includes a cell layer film (II) on which a plurality of protrusions are formed, and a back film (I) laminated on the bottom side of the cell layer film (II). And an easily tearable foam cushioning material comprising a top film (III) laminated on the top side of the cell layer film (II), wherein the back film (I) is a polyethylene resin composition (A1), The cell film (II) is a film made of a polyethylene resin composition (A2), and the top film (III) is 40 to 90% by weight of the polyethylene resin composition (B) and the cyclic olefin resin (c) 10 to 60. The top film (III) is preferably 60% to 85% by weight of the polyethylene resin composition (B) and the cyclic olefin resin (c) 15%. 40% by weight.

The shape of the easily tearable foam cushioning material of the present invention is not particularly limited, and for example, as shown in FIG.
For example, the shape of the cell layer film (II) on which a large number of protrusions are formed is a circular bag-like protrusion having a plurality of cells on the surface with air sealed inside. The shape of the cell may be a cylindrical shape, a polygonal prism shape such as a triangular prism or a quadrangular prism, a cone, a polygonal pyramid shape such as a triangular pyramid or a quadrangular pyramid, a truncated cone, a polygonal pyramid shape, or a combination thereof. Usually, the height of the air chamber is 1 to 20 mm, the bottom area is 0.5 to 15 cm ² , and the interval between the air chambers is 0.5 to 100 mm.

  As shown in FIG. 1, the easily tearable foam cushioning material has a flat back film (I), a cell layer film (II) on which a large number of protrusions are formed, and a cell layer film (II) on the top side. It is formed by laminating the laminated top film (III), and its production method is not particularly limited, and can be produced by a conventionally known method. For example, methods described in Japanese Patent Publication No. 37-13782, Japanese Patent Publication No. 38-330, Japanese Patent Application Laid-Open No. 9-123320, and the like can be applied. Further, it may optionally have a lower film (IV) laminated on the back film (I). Note that the present invention is not limited to the illustrated embodiment.

  Usually, the thickness of each film is 10-100 micrometers, More preferably, it is 10-50 micrometers.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto without departing from the gist thereof.
The various physical properties in the examples were measured according to the following procedures.

(1) Elmendorf tear strength It measured with the following apparatus and conditions based on JIS K7128-2. MD is a flow direction (MD: Machine Direction), and TD is a value in the vertical direction (TD: Transverse Direction). Originally, in JIS K7218-2, a test was made with a cut in the example and the comparative example, but in this test, the test was carried out without making a cut.
Equipment: Digital Elmendorf Tear Tester Model SA (manufactured by Toyo Seiki Seisakusho Co., Ltd.)
Measurement environment: temperature 23 ° C, humidity 50%

(2) Weight per unit area The weight per unit area of Examples and Comparative Examples was measured. The weights of Examples and Comparative Examples cut out to 10 cm × 10 cm were weighed three times with an electronic balance, and the average value was converted to g / m 2.

(3) Haze The haze was measured in accordance with JIS K7136 with the following equipment and conditions.
Apparatus: Murakami Color Research Laboratory Co., Ltd. Haze meter HM-150 type Measurement environment: Temperature 23 ° C, humidity 50%
(4) TD easy tearability It judged as follows from the state of the test piece of the TD tear strength at the time of measuring the Elmendorf tear strength of the above (1), the example after the measurement, and the comparative example.
-Linear tearability: The test specimen after measurement was visually confirmed to determine the linearity at the time of tearing. The relative evaluation was made when the linearity of the comparative example was. [Poor linearity × ⇔ ○ ⇔ Good linearity ◎]
-Easy tearability: Judged from Elmendorf tear strength. When the tear strength of the comparative example is O, the relative evaluation is ◎ when the tear strength is smaller than that of the comparative example, and × when the tear strength is larger than that of the comparative example. [Poor easy tearability × ⇔〇⇔ Easy tearability ◎]

[Raw materials]
The raw materials used in the examples are as follows.
(1) Component (a1): Ethylene / α-olefin copolymer Novatec LL “UF846” manufactured by Nippon Polyethylene
An ethylene / 1-butene copolymer having a density of 0.933 g / cm ³ and an MFR of 2.3 g / 10 min.

(2) Component (a2): High-density polyethylene Novatec HD “HY443” manufactured by Nippon Polyethylene
High density polyethylene with a density of 0.956 g / cm ³ and MFR of 1.1 g / 10 min

(3) Component (a3): High-pressure low-density polyethylene Novatec LD “LF585M” manufactured by Nippon Polyethylene
High density low density polyethylene with a density of 0.93 g / cm ³ and MFR of ³ g / 10 min.

(4) High pressure method low density polyethylene (b1)
Novatec “LC605A” manufactured by Nippon Polyethylene
High density low density polyethylene with a density of 0.918 g / cm ³ and MFR of 7.0 g / 10 min.

(5) Ethylene / α-olefin copolymer (b2)
Harmolex “NC566A” manufactured by Nippon Polyethylene
Ethylene / 1-hexene copolymer having a density of 0.918 g / cm ³ and MFR of 3.8 g / 10 min

(6) Cyclic olefin resin (c): COC
The product name TOPAS “8007” is used.
Norbornene content 36mol%

[Formation of easy tear bubble cushioning material]
The back film (I) and the cell layer film (II) are first extruded from a double-headed die as a molten thin film film composed of the composition (A) using a single extruder, and then melted. A thin film was introduced between the embossing roll and the crimping roll arranged opposite to each other.
The embossing roll has a large number of recesses formed on the roll surface, and each recess is connected to a vacuum pump. Of the two films introduced between the embossing roll and the pressure-bonding roll, the film (cell layer film) located on the embossing roll side is sucked into the concave portion when it comes into contact with the embossing roll, and a plurality of protrusions are formed. The film is bonded to the film on the pressure roll side (back film) so that air is sandwiched between the protrusions, and then cooled with a cooling roll to form a cylindrical shape having a bottom area of 78.5 mm 2 and a height of 2.5 mm. A bubble cushioning material made of a back film (I) and a cell layer film (II) in which a plurality of cells were formed was produced.
After that, on the cell layer film (II) side surface of the foam cushioning material composed of two layers of the back film (I) and the cell layer film (II), the molten thin film is formed using another extruder. The film was extruded to form a top film (III).
In addition, the foam cushioning material was manufactured so that a production rate might be 20 m / min, 25 m / min, and 30 m / min.

[Examples and Comparative Examples]
Example 1
Back film (I) and cell layer with composition (A) as 60% by weight of UF846 [component (a1)], 10% by weight of HY443 [component (a2)], and 30% by weight of LF585M [component (a3)] A bubble cushioning material made of film (II) was produced. Furthermore, NC566A [ethylene / α-olefin copolymer (b2)] 30.6% by weight, LC605A [high pressure method low density polyethylene (b1)] 40% by weight, and TOPAS8007F [cyclic olefin resin (c)] 29 A top film (III) was formed using a film consisting of .4% by weight.
The production rate was 20 m / min, and the foam cushioning material of the present invention was obtained. The evaluation results are shown in Table 1.

(Example 2)
With the same configuration as in Example 1, the production rate was 25 m / min, and the foam cushioning material of the present invention was obtained. The evaluation results are shown in Table 1.

(Example 3)
With the same configuration as in Example 1, the production rate was 30 m / min, and the foam cushioning material of the present invention was obtained. The evaluation results are shown in Table 1.

(Comparative Example 1)
Back film (I) and cell layer with composition (A) as UF846 [component (a1)] 60 wt%, HY443 [component (a2)] 10 wt%, and LF585M [component (a3)] 30 wt% Film (II) and top film (III) were formed. The production speed was 20 m / min, and a bubble cushioning material was obtained. The evaluation results are shown in Table 1.

(Comparative Example 2)
With the same configuration as in Comparative Example 1, the production speed was set to 30 m / min, and a foam cushioning material was obtained. The evaluation results are shown in Table 1.

From Table 1, compared with the comparative examples 1 and 2, Examples 1-3 are excellent in linear tearability or linear tearability, and easy tearability in TD easy tearability.
Therefore, it is clear that the easily tearable foam cushioning material of the present invention is a foam cushioning material having easy tearability that can be easily torn by hand, and has great technical significance.

  ADVANTAGE OF THE INVENTION According to this invention, the easily tearable foam cushioning material excellent in the tearability of the direction perpendicular | vertical to a longitudinal direction and a longitudinal direction is provided. Therefore, the easily tearable foam cushioning material of the present invention can be suitably used as a cushioning material used for foods, medicines, medical instruments, industrial parts, sundries, magazines, and the like, and is very useful industrially.

Claims (10)

  A cell layer film (II) having a plurality of protrusions formed thereon, a back film (I) laminated on the bottom side of the cell layer film (II), and laminated on the top side of the cell layer film (II) An easily tearable foam cushioning material having a top film (III), wherein the back film (I) is a film made of a polyethylene resin composition (A1), and the cell layer film (II) is polyethylene Characterized in that the top film (III) is a film made of a mixed resin containing the polyethylene resin composition (B) and the cyclic olefin resin (c). Easy tearing foam cushioning material. The easily tearable foam cushioning material according to claim 1, wherein the polyethylene resin compositions (A1) and (A2) comprise the following composition (A).
Composition (A): 35 to 65% by weight of the following component (a1), 0 to 30% by weight of the following component (a2) and 20 to 65% by weight of the following component (a3) [However, (a1), (a2 ) And (a3) is 100% by weight. ] The composition containing this.
Component (a1): Density 0.910 to 0.940 (g / cm ³ ), MFR 0.1 to 10 (g / 10 min) ethylene / α-olefin copolymer Component (a2): Density 0.940 -0.970 (g / cm ³ ), high density polyethylene with MFR 0.1-10 (g / 10 min) Component (a3): high pressure method low density polyethylene with MFR 0.1-10 (g / 10 min) The polyethylene resin composition (B) is made of a high pressure method low density polyethylene (b1) having a density of 0.900 to 0.940 (g / cm ³ ) and an MFR of 0.1 to 15 (g / 10 min). The easily tearable foam cushioning material according to claim 1 or 2.   4. The easy tear according to claim 3, wherein the top film (III) comprises 40 to 90 wt% of the high-pressure low-density polyethylene (b1) and 10 to 60 wt% of the cyclic olefin resin (c). Foam cushioning material. An ethylene / α-olefin copolymer (b2) in which the polyethylene resin composition (B) has a density of 0.900 to 0.940 (g / cm ³ ) and an MFR of 0.1 to 10 (g / 10 min). The easily tearable foam cushioning material according to claim 1 or 2, characterized by comprising:   The top film (III) is composed of 40 to 90% by weight of the ethylene / α-olefin copolymer (b2) and 10 to 60% by weight of the cyclic olefin resin (c). Easy tear bubble cushioning material. An ethylene / α-olefin copolymer (b2) in which the polyethylene resin composition (B) has a density of 0.900 to 0.940 (g / cm ³ ) and an MFR of 0.1 to 10 (g / 10 min). 20 to 70% by weight, high density low density polyethylene (b1) 30 to 80% by weight having a density of 0.900 to 0.940 (g / cm ³ ) and MFR 0.1 to 15 (g / 10 min) The easily tearable foam cushioning material according to claim 1, wherein:   The easy tear according to claim 7, wherein the top film (III) comprises 40 to 90% by weight of the polyethylene resin composition (B) and 10 to 60% by weight of the cyclic olefin resin (c). Foam cushioning material.   The easily tearable foam cushioning material according to any one of claims 1 to 8, wherein the cyclic olefin resin (c) is an ethylene / cyclic olefin copolymer.   The easily tearable foam cushioning material according to claim 9, wherein the glass transition point of the ethylene / cycloolefin copolymer is 60 ° C or higher.

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