JP6728766B2 - Easy-Tear Polyolefin Resin Laminated Foam Sheet - Google Patents

Description

The present invention relates to a polyolefin-based resin laminated foam sheet that is easy to tear and can be easily cut by human hands.

Conventionally, a polyolefin resin foam sheet is manufactured as follows. A thermoplastic polyolefin resin is introduced into the extruder and kneaded with a foaming agent, a cell regulator and the like under high temperature and high pressure conditions. After kneading, the melted and softened resin is extruded into a cylindrical shape from the outlet of a circular die connected to the tip of the extruder, air-cooled in the air and sent to a cooling mandrel while controlling foaming. The cylindrical sheet cooled by the cooling mandrel is cooled and then cut by a cutter, and wound as a flat sheet on a core such as a paper tube.

The polyolefin-based resin foamed sheet is usually provided in the form of a coil obtained by winding a long product. In use, the resin foam sheet is usually unwound from this winding and supplied to a device for punching or folding.

On the other hand, for cushioning of moving luggage, indoor remodeling including moving, and curing during construction, etc., the resin foam sheet is unrolled and cut with scissors or a cutter knife as needed. In this cutting operation, if you are not careful with the handling of the cutter knife, there is an unexpected danger.

In a usage mode in which the resin foam sheet is cut off as much as necessary from the winding, as long as the premise that the cushioning performance of the resin foam sheet is not impaired, tear by hand in the width direction, that is, in the direction perpendicular to the longitudinal direction. It would be convenient if possible.

However, when the resin foam sheet currently manufactured and sold is torn in the width direction by hand, it tears, but it does not tear relatively straightly.
It is uniaxially stretched in the extrusion direction and can be torn to some extent in the direction along the flow, but it is difficult to tear in the width direction.

In order to improve such a defect, a polyolefin resin laminated foam sheet in which a stretched film is laminated on at least one surface of the polyolefin resin foam sheet has been proposed. (See Patent Document 1) In the polyolefin resin foam sheet, the tear strength in the MD direction, which is the longitudinal direction in the long wound state, is smaller than the tear strength in the TD direction orthogonal to the MD direction.

JP, 2005-131952, A

However, the polyolefin resin laminated foam sheet disclosed in Patent Document 1 has a problem that it can be torn only in the stretching direction of the laminated stretched film. Further, there is a problem that the heat seal suitability on the side where the stretched films are laminated is poor.

In view of the above problems of the prior art, the present invention provides an easily tearable polyolefin resin foam sheet which has good tearability in the longitudinal direction and a direction perpendicular to the longitudinal direction and can be easily torn by hand. It is in.

As a result of intensive studies to solve the above problems, the present inventors have found that a polyolefin-based resin layer, a mixed resin layer containing a cyclic olefin-based resin and a polyolefin-based resin, and a laminate formed by laminating a polyolefin-based resin layer. The inventors have found that the above problems can be solved by stacking them on a polyolefin resin foam sheet, and based on these findings, further studies have been conducted, and the present invention has been completed.

That is, the first invention of the present application is to laminate a laminate (X) having the following layers (A), (B) and (C) in this order on at least one surface of a polyolefin resin foam sheet (Y). The easily tearable polyolefin resin laminated foamed sheet.
Layer (A): Polyolefin resin layer Layer (B): Mixed resin layer containing cyclic olefin resin (b1) and polyolefin resin Layer (C): Polyolefin resin layer

2nd invention is the said laminated body (X),
The layer (A) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (a1) and 0 to 100% by weight of a high-pressure low-density polyethylene (a2) [however, the total amount of (a1) and (a2) Is 100% by weight. ] Is a resin layer containing
The layer (B) contains 10 to 90% by weight of the cyclic olefin resin (b1) and 10 to 90% by weight of the ethylene/α-olefin copolymer (b2) [however, the total amount of (b1) and (b2) is 100% by weight. ] Is a resin layer containing
The layer (C) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 100% by weight of a high-pressure low density polyethylene (c2) [however, the total amount of (c1) and (c2) Is 100% by weight. ] The easily tearable polyolefin-based resin laminated foamed sheet according to the first aspect of the invention, characterized in that

3rd invention is the said laminated body (X),
The layer (A) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (a1) and 0 to 100% by weight of a high-pressure low-density polyethylene (a2) [however, the total amount of (a1) and (a2) Is 100% by weight. ] Is a resin layer containing
The layer (B) contains 10 to 90% by weight of a cyclic olefin resin (b1), 10 to 90% by weight of an ethylene/α-olefin copolymer (b2), and 0 to 30% by weight of a high-pressure low density polyethylene (b3). [However, the total amount of (b1), (b2) and (b3) is 100% by weight. ] Is a resin layer containing
The layer (C) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 100% by weight of a high-pressure low density polyethylene (c2) [however, the total amount of (c1) and (c2) Is 100% by weight. ] The easily tearable polyolefin-based resin laminated foam sheet according to the first invention or the second invention, characterized in that

A fourth invention is the easily tearable polyolefin resin laminated foam according to any one of the first to third inventions, characterized in that the polyolefin resin foam sheet (Y) comprises the following component (D). Exists on the seat.
Component (D): High-pressure low-density polyethylene having MFR 0.1 to 5 (g/10 minutes)

A fifth invention is the easily tearable polyolefin resin laminated foam according to any one of the first to fourth inventions, characterized in that the cyclic olefin resin (b1) is an ethylene/cyclic olefin copolymer. Exists on the seat.

In a sixth aspect of the invention, the ethylene/cyclic olefin copolymer has a weight ratio of 15 to 40/85 to 60 when the total weight of ethylene and cyclic olefin is 100. The easily tearable polyolefin-based resin laminated foam sheet according to the fifth aspect of the invention.

A seventh invention resides in the easily tearable polyolefin-based resin laminated foam sheet according to the fifth or sixth invention, wherein the ethylene/cycloolefin copolymer has a glass transition point of 60°C or higher.

An eighth invention is characterized in that, in the laminate (X), the cyclic olefin resin (b1) is contained in an amount of 3 to 60% by weight based on the total weight of the laminate (X). The easily tearable polyolefin resin laminated foam sheet according to any one of the inventions 1 to 7.

In a ninth aspect, any one of the ethylene/α-olefin copolymer (a1), the ethylene/α-olefin copolymer (b2) and the ethylene/α-olefin copolymer (c1) is 190 The easily tearable polyolefin-based resin laminated foam sheet according to the third invention is characterized in that the melt index at 0° C. is 0.1 to 30 g/10 minutes.

In a tenth aspect of the invention, in the laminate (X), the Elmendorf tear strength measured according to JIS K7128-2 is 11 N/mm or less in the MD direction (longitudinal direction) and the TD direction (lateral direction), respectively. The present invention resides in the easily tearable polyolefin resin laminated foam sheet according to any one of the first to ninth inventions.

An eleventh aspect of the invention is characterized in that the thickness of the layer (B) is 20 to 70% based on the total thickness of the laminate (X). It exists in the easily tearable polyolefin resin laminated foam sheet according to the invention.

The easily tearable polyolefin resin laminated foam sheet of the present invention has good tearability in the longitudinal direction and the direction perpendicular to the longitudinal direction, and can be easily torn by hand.

FIG. 1 is a schematic view showing the layer structure of the easily tearable polyolefin resin laminated foam sheet of the present invention.

The easily tearable polyolefin-based resin laminated foam sheet of the present invention is characterized in that a specific laminate (X) is laminated on at least one surface of the polyolefin-based resin foamed sheet (Y).
That is, as shown in FIG. 1, a laminated body 3 (X) having 4 (A layer), 5 (B layer), 6 (C layer) in this order on at least one surface of the polyolefin resin foam sheet 2 (Y). The easily tearable polyolefin resin laminated foam sheet 1 formed by laminating is the object of the present invention.
Hereinafter, the present invention will be described in detail for each item.

1. Laminate (X)
The easily tearable polyolefin resin laminated foam sheet 1 of the present invention is a laminate (X) having the following layers (A), (B) and (C) in this order on at least one surface of the foam sheet 2. ) Are laminated.
Layer (A): Polyolefin-based resin layer Layer (B): Mixed resin layer containing cyclic olefin-based resin and polyolefin-based resin Layer (C): Polyolefin-based resin layer Hereinafter, each layer will be described in detail.

(1) Layer (A)
The layer (A) in the laminate (X) used in the present invention is a polyolefin resin layer containing a polyolefin resin. Examples of the polyolefin resin include polypropylene resin and polyethylene resin, and preferably polyethylene resin.
The layer (A) is more preferably 0 to 100% by weight of the ethylene/α-olefin copolymer (a1) and 0 to 100% by weight of the high-pressure low-density polyethylene (a2) [however, (a1) and (a2)). Is 100% by weight. ] It is a resin layer containing more preferably 70 to 100% by weight of ethylene/α-olefin copolymer (a1) and 0 to 30% by weight of high-pressure low density polyethylene (a2) [provided that (a1) and The total weight of (a2) is 100% by weight. ] It is a resin layer containing.

(I) Ethylene/α-olefin copolymer (a1)
The ethylene/α-olefin copolymer (a1) used in the layer (A) 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 may be present and is preferably linear low-density polyethylene (LLDPE). Density is preferably 0.890~0.960g / cm ^3, more preferably 0.910~0.940g / cm ^3. When the density is less than 0.890 g/cm ³ , sufficient rigidity may not be obtained, and the laminate (X) may be blocked, resulting in poor workability. On the other hand, when the density exceeds 0.960 g/cm ³ , there is a possibility that sufficient fusion bonding with the polyolefin resin foam sheet (Y) may not be obtained.
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 (a1) is preferably 0.1 to 30 g/10 minutes at 190°C. It is more preferably 0.5 to 4.0 g/10 minutes. When the MFR is less than 0.1 g/10 minutes, the melt flowability is poor, the film processing of the laminate (X) becomes difficult, and there is a possibility that the motor load may increase, which is not preferable. On the other hand, when it exceeds 30 g/10 minutes, the melt viscosity is too low and the film-forming stability during film processing of the laminate (X) may be reduced, 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.

In the ethylene/α-olefin copolymer (a1), the content of α-olefin copolymerized with ethylene is 0.1 to 15 mol%, preferably 0.5 to 10 mol%, particularly preferably 0. 0.5 to 5 mol %, and the type of α-olefin is usually an α-olefin having 3 to 8 carbon atoms, and specifically, propylene, butene-1, pentene-1, hexene-1, heptene. -1, octene-1, 4-methylpentene-1 can be mentioned.

(II) High pressure low density polyethylene (a2)
The high-pressure low-density polyethylene (a2) (also referred to as LDPE) used in the present invention is homopolyethylene and is polymerized with an organic peroxide.
The density of the high-pressure method low density polyethylene (a2) is selected from the range of 0.915 to 0.935 g/cm ³ , preferably 0.920 to 0.930 g/cm ³ , and more preferably 0.922. -0.929 g/cm< ³ >. When the density is less than 0.915 g/cm ³ , perforation tends to occur during molding of the laminate (X), and a film having a good appearance may not be obtained. On the other hand, when the density exceeds 0.935 g/cm ³ , the processing stability of the laminate (X) may not be obtained.
In the present invention, the density is a value measured based on JIS K 6922-2.

(2) Layer (B)
The layer (B) in the laminate (X) used in the present invention is a mixed resin layer containing the cyclic olefin resin (b1) and the polyolefin resin.
More preferably, the layer (B) is a resin layer containing a cyclic olefin resin (b1) and an ethylene/α-olefin copolymer, and further preferably, the layer (B) is a cyclic olefin resin (b1). ) 10-90% by weight, an ethylene/α-olefin copolymer (b2) 10-90% by weight, and a high-pressure low density polyethylene (b3) 0-30% by weight, a resin layer [(b1), ( The total amount of b2) and (b3) is 100% by weight].
If the amount of the cyclic olefin resin is less than 10% by weight, sufficient tearability may not be obtained, which is not preferable.

(I) Cyclic olefin resin (b1)
Examples of the cyclic olefin-based resin (b1) used in the layer (B) of the present invention include a norbornene-based polymer, a vinyl alicyclic hydrocarbon polymer, and a cyclic conjugated diene polymer. Among these, norbornene-based polymers are preferable. Examples of the norbornene-based polymer include a ring-opening polymer of a norbornene-based monomer (hereinafter also referred to as “COP”) and a norbornene-based copolymer obtained by copolymerizing a norbornene-based monomer with an α-olefin such as ethylene. Combined (hereinafter, also referred to as “COC”) and the like can be mentioned. Further, hydrogenated products of COP and COC can also be used.

COC includes linear monomers such as α-olefins such as ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and cyclic monomers such as tetracyclododecene and norbornene. And a cyclic olefin copolymer obtained from More specifically, the above 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 its derivatives, tetracyclo[4.4.0.1.2,5.17,10]-3-dodecene and its derivatives, 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[8.4.0]. .12,5.19,12.08,13]-3-hexadecene and its derivative, pentacyclo[6.6.1.13,6.02,7.09,14]-4-hexadecene and its derivative, hexacyclo [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 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 its derivatives, octacyclo[8.8.0.12]. 9.14, 7.111, 18.113, 16.03, 8.012, 17]-5-dococene and its derivatives, nonacyclo[10.9.1.14,7.113,20.115,18. [02, 10.03, 8.012, 21.014, 19]-5-Pentacocene and cyclic olefin copolymers made of copolymers with cyclic olefins such as derivatives thereof. The linear monomer and the cyclic monomer may be used alone or in combination of two or more kinds. Further, such cyclic olefin copolymers can be used alone or in combination. Further, the COP and COC can be used in combination with the cyclic olefin resin (b1). In that case, different performances of COP and COC can be provided.

In the present invention, the cyclic olefin resin (b1) is preferably COC from the viewpoint of dispersibility in 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.

Further, in the present invention, the ethylene/cycloolefin copolymer has a content ratio of ethylene/cycloolefin of 15 to 40/85 to 60 when the total weight of ethylene and the cycloolefin is 100. It is preferably, and more preferably 30-40/70-60. When the content of ethylene is less than 15% by weight, the rigidity becomes too high and the inflation moldability and bag-making suitability are deteriorated, which is not preferable. On the other hand, when the content of ethylene is 40% by weight or more, sufficient easy tearability and rigidity cannot be obtained, which is not preferable. When the content ratio is within this range, the rigidity, tearability, processing stability and impact strength of the film are improved, which is preferable.

Furthermore, the ethylene/cyclic olefin copolymer preferably has a glass transition point of 60° C. or higher. More preferably, it is 70° C. or higher. When the content of the cyclic olefin is less than the above range, the glass transition point becomes less than the above range, for example, the barrier property of the aromatic component is lowered, sufficient rigidity cannot be obtained, and high speed packaging machine is suitable. May be inferior to 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 deteriorate, which is not preferable.
The weight average molecular weight of the cyclic olefin resin (b1) is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

The cyclic olefin resin (b1) is preferably contained in the resin layer (B) in an amount of 10 to 90% by weight, more preferably 20 to 80% by weight. Further, it is preferably contained in an amount of 3 to 60% by weight based on the total weight of the laminate (X). It is more preferably 5 to 50% by weight, and further preferably 6 to 40% by weight. If the content is too small, sufficient easy tearability cannot be obtained, which is not preferable. On the other hand, if the content is too large, the rigidity becomes too high, and the inflation moldability and bag making suitability are deteriorated, which is not preferable.

As a commercially available product that can be used as the cyclic olefin resin (b1), examples of the ring-opening polymer (COP) of a norbornene-based monomer include “ZEONOR” manufactured by Nippon Zeon Co., Ltd., and the norbornene-based resin. Examples of the copolymer (COC) include “Apel” manufactured by Mitsui Chemicals, Inc. and “TOPAS” manufactured by Ticona. In the present invention, TOPAS grade 8007 is preferable because the content ratio of the norbornene-based monomer is within the above range and the processability and the like.

(II) Polyolefin Resin As the polyolefin resin used for the layer (B), polypropylene resin, polyethylene resin and the like can be used, and preferably polyethylene resin.

(III) Ethylene/α-olefin copolymer (b2)
The ethylene/α-olefin copolymer (b2) used in the layer (B) is a copolymer of ethylene and α-olefin, and is any one of those polymerized with a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. It may be present and is preferably linear low-density polyethylene (LLDPE). Density is preferably 0.870~0.935g / cm ^3, more preferably 0.910~0.933g / cm ^3. When the density is less than 0.870 g/cm ³ , sufficient rigidity cannot be obtained, and when the laminate (X) is used as the lower film (III), workability such as winding around a roll may be poor. .. On the other hand, when the density exceeds 0.935 g/cm ³ , there is a possibility that sufficient fusion with the adjacent film may not be obtained, and the secondary processability may be poor.
In the present invention, the density is a value measured based on JIS K 6922-2.

Further, the melt flow rate (MFR) of the ethylene/α-olefin copolymer (b2) is preferably 0.1 to 30 g/10 minutes at 190°C. It is more preferably 0.5 to 4.0 g/10 minutes. If the MFR is less than 0.1 g/10 minutes, the melt flowability is poor, the film processing of the laminate (X) may become difficult, and the motor load may increase, which is not preferable. On the other hand, when it exceeds 30 g/10 minutes, the melt viscosity is too low and the film-forming stability during film processing of the laminate (X) may be reduced, 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.

The ethylene/α-olefin copolymer (b2) used in the present invention is specifically 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 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 can be mentioned.

(IV) High pressure method low density polyethylene (b3)
The high-pressure low-density polyethylene (b3) used in the present invention is homopolyethylene, also called LDPE, which is polymerized with an organic peroxide.
The density is preferably selected from the range of 0.915 to 0.935 g/cm ³ , more preferably 0.920 to 0.930 g/cm ³ , and further preferably 0.922 to 0.929 g/cm 3. It is ³ . When a high-pressure low-density polyethylene having a density of less than 0.915 g/cm ³ is used for the layer (B), perforation is likely to occur during molding of the laminate (X), 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 , the processing stability of the laminate (X) may not be obtained.
In the present invention, the density is a value measured based on JIS K 6922-2.

(3) Layer (C)
The layer (C) in the laminate (X) used in the present invention is a polyolefin resin layer containing a polyolefin resin.
Preferably, the layer (C) can use polypropylene resin, polyethylene resin, or the like, and more preferably polyethylene resin. More preferably, the layer (C) comprises 0 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 100% by weight of a high-pressure low-density polyethylene (c2) [provided that (c1) and (c2) are present. Is 100% by weight. ] It is a resin layer containing. More preferably, the layer (C) is composed of 70 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 30% by weight of a high-pressure low density polyethylene (c2) [however, (c1) and (c2)). Is 100% by weight. ] It is a resin layer containing.

(C) Ethylene/α-olefin copolymer (c1)
The ethylene/α-olefin copolymer (c1) used to form the layer (C) is a copolymer of ethylene and α-olefin, and is polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. Any of these may be used, and linear low-density polyethylene (LLDPE) is preferable. Density is preferably 0.890~0.960g / cm ^3, more preferably 0.910~0.940g / cm ^3. When the density is less than 0.890 g/cm ³ , sufficient rigidity may not be obtained, and the laminate (X) may be blocked, resulting in poor workability. On the other hand, when the density exceeds 0.960 g/cm ³ , sufficient fusion bonding with the adjacent film cannot be obtained, and the secondary processability may be poor.
In the present invention, the density is a value measured based on JIS K 6922-2.

Further, the melt flow rate (MFR) of the ethylene/α-olefin copolymer (c1) is preferably 0.1 to 30 g/10 minutes at 190°C. It is more preferably 0.5 to 4.0 g/10 minutes. When the MFR is less than 0.1 g/10 minutes, the melt flowability is poor, the film processing of the laminate (X) may be difficult, and the motor load may increase, which is not preferable. On the other hand, when it exceeds 30 g/10 minutes, the melt viscosity is too low and the film-forming stability during film processing of the laminate (X) may be reduced, 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.

The ethylene/α-olefin copolymer (c1) used in the present invention is specifically 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 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 can be mentioned.

(B) High-pressure method low-density polyethylene (c2)
The high-pressure low-density polyethylene (c2, hereinafter also referred to as “LDPE(c2)”) used in the present invention is homopolyethylene and is polymerized with an organic peroxide. The density is selected from the range of 0.915 to 0.935 g/cm ³ , but is preferably 0.920 to 0.930 g/cm ³ , and more preferably 0.922 to 0.929 g/cm ³ . .. When a high-pressure low-density polyethylene having a density of less than 0.915 g/cm ³ is used for the layer (C), perforation is likely to occur during molding of the laminate (X), 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 , the processing stability of the laminate (X) may not be obtained.
In the present invention, the density is a value measured based on JIS K 6922-2.

In the present invention, the layer (A), the layer (B) and the layer (C) include an antifogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent and a release agent. Ingredients such as an ultraviolet absorber and a coloring agent can be added within a range that does not impair the object of the present invention. In particular, it is preferable that the friction coefficient of the layer (A) and the layer (C) is 1.5 or less, particularly 1.2 or less, in order to impart processability during film forming and packaging suitability for a filling machine. It is preferable to appropriately add a lubricant or an anti-blocking agent to the layer (A) and the layer (C).

(4) Laminate (X)
As described above, the laminate (X) used in the present invention has a structure of specific layer (A)/specific layer (B)/specific layer (C). FIG. 1 shows a schematic view of a cross section of an example of a film containing the laminate (X) used in the present invention. The (A) layer side is the side laminated on one side of the foamed sheet (Y).
The total thickness of the laminated body (X) is preferably 30 to 150 μm. When the thickness of the laminate (X) is 30 μm or more, excellent secondary workability can be obtained.

Further, the thickness of the layer (B) in the laminate (X) used in the present invention is preferably 20 to 70% based on the entire laminate (X). It is more preferably 20 to 50%. That is, the layer (A)/layer (B)/layer (C) can have a thickness of about 1:0.5:1 to about 1:4:1. When the layer (B) is thinner than 20%, sufficient tearability cannot be obtained, which is not preferable. On the other hand, if the thickness is more than 70%, the rigidity becomes too high, and the inflation moldability and bag making suitability are deteriorated, which is not preferable. When the layer (B) is in this range, it is preferable because it is excellent in easy tearability, is advantageous in cost, and improves the tearability and pinhole resistance of the laminate (X).

The method for producing the laminate (X) used in the present invention is not particularly limited, but for example, the ethylene/α-olefin copolymer (a1) and/or the high-pressure low-density polyethylene (a2) used in the layer (A) are used. ), the cyclic olefin resin (b1) and/or the ethylene/α-olefin copolymer (b2) and/or the high-pressure low density polyethylene (b3) used in the layer (B), and the ethylene used in the layer (C). The α-olefin copolymer (c1) and/or the high-pressure low-density polyethylene (c2) are heated and melted in different extruders, and are melted by a method such as a co-extrusion multilayer die method or a feed block method. A coextrusion method in which (A)/(B)/(C) are laminated in this order and then formed into a film by inflation, T-die/chill roll method, or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film having excellent hygiene and cost performance can be obtained. Furthermore, since there is a large difference in softening point (melting point) between the ethylene/α-olefin copolymer (b2) and the high-pressure low-density polyethylene (b3) used in the present invention and the cyclic olefin resin (b1), phase separation or This may result in gel. In order to suppress such phase separation and gel generation, the T-die/chill-roll method, which allows melt extrusion at a relatively high temperature, is preferable.
Further, since the laminate (X) used in the present invention is obtained as a substantially non-stretched multilayer film by the above-mentioned production method, it is possible to carry out secondary forming such as deep drawing by vacuum forming.

The laminated body (X) used in the present invention preferably has Elmendorf tear strength measured in accordance with JIS K7128-2 of 11 N/mm or less in the machine direction (MD) and the transverse direction (TD), respectively. , More preferably 8 to 1 N/mm, further preferably 5 to 1 N/mm. When the Elmendorf tear strength exceeds 11 N/mm, it becomes difficult to tear the bubble cushioning material by hand easily.

2. Polyolefin resin foam sheet (Y)
The polyolefin-based resin laminated foam sheet 1 of the present invention (hereinafter sometimes simply referred to as “laminated foam sheet”) has the above-mentioned laminated structure on at least one side of a polyolefin-based resin foam sheet (hereinafter sometimes simply referred to as “foamed sheet”). The body (X) is laminated.
The polyolefin-based resin foam sheet (Y) is a sheet-shaped foam made of a polyolefin-based resin. As the polyolefin-based resin that forms the basis of the foamed sheet, for example, polyethylene-based resin, polypropylene-based resin or the like can be used alone or in combination of two or more.
Examples of the polyethylene resin include ethylene homopolymers, and copolymers of ethylene and other monomers, which may be used alone or in combination of two or more. Examples of ethylene homopolymers include low density polyethylene, linear low density polyethylene, medium density polyethylene, and high density polyethylene. Examples of the other monomer forming a copolymer with ethylene include vinyl acetate, propylene, α-olefin (1-butene, etc.), styrene, acrylic ester, acrylonitrile, vinyl chloride and the like. As the copolymer, one having a ratio of the above-mentioned other monomer components of 30% by mass or less is preferably used. In addition, other resins may be mixed with the polyethylene-based resin as long as the effects of the present invention are not impaired. Examples of the other resin include polystyrene, polyvinyl chloride, polyacrylonitrile, α-olefin copolymerized polyethylene, and acrylic acid ester. Other resins are preferably mixed in a ratio of 30% by mass or less based on the total amount of the resins.
Examples of the polypropylene-based resin include general-purpose polypropylene-based resins such as propylene homopolymer and ethylene-propylene copolymer, and copolymers of propylene and other monomers, alone or in combination with 2 It can be used as a mixture of two or more species.

As the foaming agent for foaming the polyolefin resin, either a volatile foaming agent or a decomposable foaming agent may be used. Examples of volatile foaming agents include a wide variety of inert gases, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers, ketones, and the like. Among them, examples of the inert gas include carbon dioxide gas, nitrogen, etc. Is mentioned. Examples of aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), and examples of alicyclic hydrocarbons include cyclopentane, cyclohexane, etc. To be Examples of the halogenated hydrocarbon include one or two or more halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane and difluoroethane. Further, examples of the ether include dimethyl ether and diethyl ether, and examples of the ketone include acetone and methyl ethyl ketone.
Examples of the decomposing foaming agent include inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compound, sodium borohydride, azodicarbonamide, barium azodicarboxylate, and dinitrosopentamethylene. Examples include organic foaming agents such as tetramine.
The foaming agents may be used alone or in combination of two or more.
A general extrusion foaming method using a volatile foaming agent is to knead low-density polyethylene in an extruder under pressure and heating, and then continuously extruding it into a low pressure region such as the atmosphere while press-fitting the volatile foaming agent. To foam. In this case, the effect of cooling the molten resin due to the latent heat of vaporization of the volatile foaming agent can be expected during extrusion foaming, and it becomes easy to maintain the formation of a bubble film during foaming. Therefore, it is possible to produce a low-density foam having a good appearance and a small number of open cells.
On the other hand, the extrusion foaming method in the case of using the decomposable foaming agent, the low density polyethylene and the decomposable foaming agent are supplied to the extruder, while melt kneading in the extruder, the decomposition temperature of the decomposable foaming agent or more It is heated under pressure and then extruded in the low pressure region to foam. In this method, the latent heat of vaporization at the time of foaming such as a volatile foaming agent cannot be expected, so that it becomes difficult to maintain the formation of a bubble film at the time of foaming. Therefore, even if the amount of the decomposition-type foaming agent added is increased in order to obtain a foam having a low density, there may be many open cells and only a foam having a poor appearance may be obtained.
However, among the decomposable foaming agents, the organic foaming agent functions as a cell nucleating agent when used in combination with a volatile foaming agent such as an aliphatic hydrocarbon, and is dense and has an average cell diameter of 2.5 mm or less, for example. It functions to form a uniform foam having uniform cell diameters. Therefore, a particularly preferable foaming agent includes a combination system of an aliphatic hydrocarbon and an organic decomposition type foaming agent.

Polyolefin-based resin, as long as it does not impair the foaming property, if necessary, a light-stabilizing agent such as a foaming aid, a lubricant, an anti-shrinking agent, an antioxidant, an antistatic agent, a flame retardant, an ultraviolet absorber, and a hindered amine compound. Various additives such as agents, colorants, inorganic cell nucleating agents, and inorganic fillers may be added.

As a method for producing the polyolefin resin foam sheet (Y), an extrusion foaming method is used as in the conventional case. As an extruder used for extrusion foaming, a single-screw extruder, a twin-screw extruder, or an extruder in which a plurality of these extruders are connected can be used. In any of the extruders, it is desirable to provide a pressure inlet for the foaming agent in the middle of the barrel, and when using a volatile foaming agent, press this through the pressure inlet and knead with the non-crosslinked polyethylene resin. As a die attached to the tip of the extruder, either a circular die or a T die can be used, but it is preferable to adopt a process using a circular die in consideration of the thickness uniformity in the width direction.
First, a polyolefin resin and a foaming agent are supplied to an extruder, melt-kneaded, and then extruded in a cylindrical shape through the circular die to foam. Next, this tubular foam is taken along the outer periphery of the annular mandrel and cooled. Specifically, air is blown from the mandrel to the inside of the foam, and the mandrel itself is cooled by water cooling, and air is blown and cooled to the outside of the foam. When the cooled cylindrical foam is cut into a sheet with a rotary blade or the like, the foamed sheet is continuously and efficiently manufactured. It is preferable to control the temperature of the cooling water passed through the mandrel within the range of 20 to 35°C.

3. Polyolefin-based resin laminated foam sheet The polyolefin-based laminated foam sheet of the present invention can be produced by laminating and integrating the polyolefin-based resin foam sheet (Y) with the laminate (X). As a laminating method, a conventionally known general laminating method such as a thermal laminating method or a laminating method using a hot melt adhesive can be adopted.
The polyolefin-based resin laminated foam sheet of the present invention has the above-mentioned configuration so that it can be easily torn in the MD and TD directions by human hands, so that the efficiency of the packaging work can be improved. In addition, since it is not necessary to use a cutter or the like when cutting the laminated foam sheet, it is possible to reduce the risk of working.

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.
In addition, the measurement of various physical properties in Examples was performed according to the following procedures.

[Measuring method]

(1) Tearability evaluation by hand The bubble cushioning material was slowly and intermittently torn in the longitudinal direction and the direction perpendicular to the longitudinal direction.
The one that can always be torn even if it is torn intermittently was marked as ○, and the one that could not be torn was marked as ×.

[Molding conditions for blown film and method for evaluating moldability]
Using the following inflation film film forming machine (molding apparatus), the laminate (X) was molded and evaluated under the following molding conditions.

(3 types, 3 layers inflation molding machine)
Equipment: Inflation molding equipment (manufactured by Placo Co., Ltd.)
Extruder screw diameter: 50 mmφ x 2, 55 mmφ x 1
Die diameter: 200mmφ
Extrusion rate: 25 kg/hr
Die lip gap: 3mm
Collection speed: 23m/min Blow-up ratio: 2.0
Molding resin temperature: 180℃
Film thickness: 30 μm
Cooling ring: 2-stage air cooling ring

[Materials used]
The raw materials used in the examples are as follows.
(1) Ethylene/α-olefin copolymer (a1)(c1)
Novatec LL "UF421" manufactured by Nippon Polyethylene Co., Ltd.
Ethylene/1-butene copolymer (2) ethylene/α-olefin copolymer (b2) having a density of 0.924 g/cm ³ and an MFR of 0.9 g/10 min.
Novatec LL "UF320" manufactured by Nippon Polyethylene Co., Ltd.
Ethylene/1-butene copolymer (3) with a density of 0.922 g/cm ³ and MFR of 0.9 g/10 minutes (3) Cyclic olefin resin (b1): COC
Product name TOPAS "8007" is used.
Norbornene content 36 mol%
[Polyolefin resin foam sheet (Y)]
A highly foamed polyethylene sheet #210×1200 manufactured by Sakai Chemical Industry Co., Ltd. having a thickness of about 1 mm was used.

[Formation of polyolefin resin laminated foam sheet]
[Examples and Comparative Examples]
<Example 1>
As shown in Table 1, as the layered product (X), the layer (A) is an ethylene/α-olefin copolymer (a1)UF421, the layer (C) is an ethylene/α-olefin copolymer (c1)UF421, and a layer ( Using B/) ethylene/α-olefin copolymer (b2) UF320 and cyclic olefin resin (b1) COC, a 30 μm blown film having a layer ratio of 1:1:1 was obtained.
The polyolefin resin foamed sheet (Y) is overlaid with the laminate (X), the temperature of the 400φ dielectric heating roll is set to 140° C., and the fusing speed is set to 45 m/min. Obtained.
The evaluation results are shown in Table 1.
The tearability of the obtained polyolefin resin laminated foam sheet was evaluated by hand. As a result, it was possible to tear in the longitudinal direction and in the direction perpendicular to the longitudinal direction.

<Comparative Example 1>
The tearability was evaluated by hand using only the polyolefin resin foam sheet.
The evaluation results are shown in Table 1. This product tears in the longitudinal direction, but it was difficult to tear in the direction perpendicular to the longitudinal direction.
<Comparative example 2>
A polyolefin resin foam sheet was obtained in the same manner as in Example 1 except that UF320 was used for the layer (B).
The evaluation results are shown in Table 1.
It could be torn in the longitudinal direction, but could not be torn in the direction perpendicular to the longitudinal direction.

From the results of Table 1, Example 1 satisfying the requirements of the present invention has good tearability in the longitudinal direction and the direction perpendicular to the longitudinal direction. On the other hand, Comparative Example 1 in which the laminate (X) was not used and Comparative Example 2 in which the cyclic olefin resin (b1) was not used in the laminate (X) were inferior in tearability in the direction perpendicular to the longitudinal direction.
Therefore, it is apparent that the polyolefin-based resin foamed laminated sheet of the present invention is a polyolefin-based resin laminated foamed sheet 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 polyolefin resin foam laminated sheet which is excellent in the tearability of the longitudinal direction and the direction perpendicular to the longitudinal direction is provided. Therefore, the easily tearable polyolefin resin foamed laminated sheet of the present invention can be preferably used as a cushioning material for applications such as foods, medicines, medical instruments, industrial parts, miscellaneous goods, and magazines, and is industrially very useful. is there.

1... Easily tearable polyolefin resin laminated foam sheet 2... Polyolefin resin foam sheet (Y)
3... Laminate (X)
4... Layer (A)
5... Layer (B)
6... Layer (C)

Claims (11)

A laminate (X) having the following layers (A), (B) and (C) in this order is laminated on at least one surface of a polyolefin resin foam sheet (Y), and is perpendicular to the longitudinal direction and the longitudinal direction. Tearable polyolefin-based resin laminated foam sheet having tearability in various directions .
Layer (A): Polyolefin resin layer Layer (B): Mixed resin layer containing cyclic olefin resin (b1) and polyolefin resin Layer (C): Polyolefin resin layer The laminate (X) is
The layer (A) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (a1) and 0 to 100% by weight of a high-pressure low-density polyethylene (a2) [however, the total amount of (a1) and (a2) Is 100% by weight. ] Is a resin layer containing
The layer (B) contains 10 to 90% by weight of the cyclic olefin resin (b1) and 10 to 90% by weight of the ethylene/α-olefin copolymer (b2) [however, the total amount of (b1) and (b2) is 100% by weight. ] Is a resin layer containing
The layer (C) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 100% by weight of a high-pressure low density polyethylene (c2) [however, the total amount of (c1) and (c2) Is 100% by weight. ] The easily tearable polyolefin-based resin laminated foam sheet according to claim 1, which is a resin layer containing The laminate (X) is
The layer (A) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (a1) and 0 to 100% by weight of a high-pressure low-density polyethylene (a2) [however, the total amount of (a1) and (a2) Is 100% by weight. ] Is a resin layer containing
The layer (B) contains 10 to 90% by weight of a cyclic olefin resin (b1), 10 to 90% by weight of an ethylene/α-olefin copolymer (b2), and 0 to 30% by weight of a high-pressure low density polyethylene (b3). [However, the total amount of (b1), (b2) and (b3) is 100% by weight. ] Is a resin layer containing
The layer (C) contains 0 to 100% by weight of an ethylene/α-olefin copolymer (c1) and 0 to 100% by weight of a high-pressure low density polyethylene (c2) [however, the total amount of (c1) and (c2) Is 100% by weight. ] The easily tearable polyolefin-based resin laminated foam sheet according to claim 1 or 2, which is a resin layer containing. The easily tearable polyolefin resin laminated foam sheet according to any one of claims 1 to 3, wherein the polyolefin resin foam sheet (Y) comprises the following component (D).
Component (D): High-pressure low-density polyethylene having MFR 0.1 to 5 (g/10 minutes) The easily tearable polyolefin resin laminated foam sheet according to any one of claims 1 to 4, wherein the cyclic olefin resin (b1) is an ethylene/cyclic olefin copolymer. The content ratio of ethylene/cyclic olefin in the ethylene/cyclic olefin copolymer is 15-40/85-60 in weight ratio when the total weight of ethylene and cyclic olefin is 100. The easily tearable polyolefin resin laminated foam sheet according to claim 5. The ethylene/cyclic olefin copolymer has a glass transition point of 60° C. or higher, and the easily tearable polyolefin resin laminated foam sheet according to claim 5 or 6. In the laminate (X), the cyclic olefin resin (b1) is contained in an amount of 3 to 60% by weight based on the total weight of the laminate (X). 2. An easily tearable polyolefin resin laminated foam sheet according to item 1. Any one of the ethylene/α-olefin copolymer (a1), the ethylene/α-olefin copolymer (b2) and the ethylene/α-olefin copolymer (c1) has a melt index at 190° C. of 0. 0.1 to 30 g/10 minutes, The easily tearable polyolefin resin laminated foam sheet according to claim 3. In the laminate (X), the Elmendorf tear strength measured according to JIS K7128-2 is 11 N/mm or less in the MD direction (longitudinal direction) and the TD direction (horizontal direction), respectively. The easily tearable polyolefin resin laminated foam sheet according to any one of claims 1 to 9. The thickness of the layer (B) is from 20 to 70% based on the total thickness of the laminate (X), and the layer according to any one of claims 1 to 10 is characterized in that. Tearable polyolefin resin laminated foam sheet.

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