JP2017222090A - Film for mushroom bed cultivation bags and mushroom bed cultivation bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for mushroom bed cultivation bags that is excellent in tearability in a longitudinal direction and a lateral direction and pinhole resistance and maintains the excellent tearability in the longitudinal direction and the lateral direction even after a heat treatment, and a mushroom bed cultivation bag.SOLUTION: A multilayer film has an outer layer (A) containing high density polyethylene having density of 0.945 to 0.966 g/cm(a1), an intermediate layer (B) containing 20 to 90 wt.% of a cyclic olefin-based resin having glass transition point of 105°C or more (b1) and another polyethylene-based resin, and an inner layer (C) containing high density polyethylene having density of 0.945 to 0.966 g/cm(c1) in the stated order (optionally, each layer further containing an ethylene α-olefin copolymer) and is used as a film for mushroom bed cultivation bags.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film for a fungus bed cultivation bag and a fungus bed cultivation bag. More specifically, it is excellent in tearing property in the longitudinal direction and the transverse direction and puncture resistance, and is excellent in tearing property in the longitudinal direction and the transverse direction even after heat treatment. The present invention relates to a fungus bed cultivation bag film and a fungus bed cultivation bag composed of a multilayer film.

  For cultivation of mushrooms, a method using fungus bed cultivation is used from the viewpoint of productivity. In fungus bed cultivation, prepare a fungus bed that mixes woody base materials such as sawdust using trees that match the type of mushrooms to be cultivated, and nutrient sources such as rice bran and minerals in an appropriate container. The inoculum seeded on the fungus bed is cultured. In addition to bottles and flat boxes, plastic film bags are used as containers for filling the fungus bed, particularly in the cultivation of shiitake and maitake (Patent Document 1).

  The fungus bed after bagging needs to sterilize harmful bacteria that adversely affect the mycelium and fruit bodies of mushrooms. However, since sterilization with drugs is not permitted in fungus bed cultivation, sterilization is performed by applying heat at 98 ° C. for 4 hours or more, for example. For this reason, the bag for fungus bed cultivation is required to have high heat resistance. Moreover, in order to prevent harmful bacteria from being mixed into the fungus bed in the inoculum culture step, it is desirable that the bag for cultivation of the fungus bed has physical characteristics such as puncture resistance. On the other hand, in the process of generating and growing mushrooms, it is necessary to remove the bag in order to take out the fungus bed in which the inoculum was cultured, but from the viewpoint of workability and safety, the bag for fungus bed cultivation is It has to be easily tearable (Patent Document 2).

  Conventional polyethylene film, polypropylene film, etc. are used for the plastic film used in conventional fungus bed cultivation bags. Among them, for example, it is necessary as a container that reliably protects the contents and has heat sealability. Ethylene / α-olefin co-polymer with excellent transparency, tear resistance, low temperature heat sealability, hot tack, sealability of narrow materials, heat seal strength, bag breaking strength, heat resistance, etc. The use of coalescence (LLDPE) has been proposed.

  However, in LLDPE, ethylene / α-olefin copolymer (C4-LLDPE), which is a copolymer of ethylene and 1-butene, is not sufficiently improved in tearability and hot tackiness, and content protection The point was not enough. That is, in applications involving tear-opening, such as bags for fungus bed cultivation, the ethylene / α-olefin copolymer alone has the disadvantages that tear strength and elongation are large and tear-opening is difficult, and it is not necessarily a suitable material. I could not say.

  Also, commercially available ethylene / α-olefin copolymers (LLDPE) are often blended with high-pressure low-density polyethylene (LDPE) to improve processability. In this case, although tearing and opening are easy in the vertical direction, there is still a drawback that tearing and opening is difficult in the horizontal direction.

  On the other hand, in polyethylene films used for easy tearable packaging bags used for general packaging bags, in recent years, in order to improve such defects, an attempt is made to impart cutability by using a cyclic olefin resin. Attempts have been made.

  For example, the intermediate layer is composed of a cyclic olefin-based resin layer, and on the surface thereof, an easily cut laminate in which linear medium density polyethylene and / or linear low density polyethylene resin layer each provided at least one layer is laminated. Film for packaging (see Patent Document 3), a packaging film comprising a laminate comprising a base material layer / intermediate layer / inner layer, the intermediate layer comprising 50 to 95% by weight of linear low density polyethylene, cyclic olefin, a packaging film comprising a composition comprising 5 to 50% by weight of an α-olefin copolymer, the inner layer comprising a layer of a specific linear low density polyethylene (see Patent Document 4), Outer layer made of specific linear low density polyethylene, consisting of a mixture of 60 to 90% by weight of linear low density polyethylene and 10 to 40% by weight of cyclic polyolefin A laminated polyolefin film excellent in transparency (Patent Document 5), wherein an inner layer constituting a heat seal layer composed of an interlayer and a specific linear low density polyethylene is laminated in order, and a polyolefin capable of being formed A packaging film (Patent Document 6) having at least a polyolefin-based resin layer made of a mixed resin obtained by mixing 3 to 50% by weight of a cyclic polyolefin-based resin with a base-based resin is known.

  Attempts have also been made to improve cutability by using a combination of ionomer resins.

  For example, a coextruded multilayer film or sheet by an inflation method, wherein at least one layer is composed of an ethylene polymer or a resin composition layer mainly composed of this, and the other at least one layer is composed of polyolefin resin 60 to A multilayer film or sheet excellent in lateral and / or longitudinal tear properties (20) and 20 to 40 parts by weight of an ionomer resin is known. ing.

  In addition, an outer layer made of specific polyethylene, an intermediate layer made of 60 to 90% by weight of a cyclic olefin resin and 10 to 40% by weight of a specific linear low density polyethylene, and an inner layer made of polyethylene having a specific density are sequentially laminated. An easily tearable multilayer film (Patent Document 8) is proposed.

JP-A-6-90622 Utility Model Registration No. 3192358 Japanese Patent Laid-Open No. 11-129415 JP-A-10-237234 JP 2004-284351 A JP 2005-298055 A JP-A-2005-144799 JP 2012-885 A

  However, the fungus bed cultivation bag described in Patent Document 2 does not impart easy tearability due to the physical properties of the bag, but is provided with a mechanism for tearing at a specific site by providing a cleavage induction portion, and has a simple structure. However, it was not satisfactory from the viewpoint of enabling easy tearing. Further, the films of Patent Documents 3 to 8 or packaging materials using these films have a problem that easy tearability is lost when heat and pressure sterilization is performed. Since a sterilization process by heating is indispensable for bags for fungus bed cultivation, a film having easy tearability after heat treatment has been demanded. Moreover, since the film is generally thin, it is required to have excellent pinhole resistance, particularly puncture resistance, from the viewpoint of preventing harmful bacteria from being mixed, and it is desired to achieve both easy tearability.

  In view of the above-mentioned problems of the prior art, the object of the present invention is excellent in longitudinal and lateral tearability and puncture resistance, and excellent in longitudinal and lateral tearability even after heat treatment, for fungus bed cultivation. It is in providing a film and a fungus bed cultivation bag.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors, as a plastic film constituting a bag-like body, a layer I containing high-density polyethylene of a specific density, a cyclic olefin system having a specific glass transition point A multilayer film having a layer II containing a specific amount of resin and a specific amount of other polyethylene-based resin, a layer III containing a high-density polyethylene of a specific density, and preferably, an ethylene / α-olefin in layers I to III It has been found that the above problems can be solved by a multilayer film containing a copolymer. These findings have been further studied and the present invention has been completed.

That is, the present invention includes the following inventions.
[1] A film for a fungus bed cultivation bag for constituting a bag-like body for storing a fungus bed, comprising a high density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ (A) 20% by weight to 90% by weight of a cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher, a second layer (B) containing another polyethylene resin, and a density of 0.945 A film for a fungus bed cultivation bag, which is a multilayer film having at least three layers of the third layer (C) containing 0.966 g / cm ³ of high-density polyethylene (c1) in order.
[2] The film for fungus bed cultivation bags according to [1], wherein the cyclic olefin-based resin (b1) is an ethylene / cyclic olefin copolymer.
[3] The Elmendorf tear strength measured in accordance with JIS K7128-2 after the heat treatment at 120 ° C. for 60 minutes of the multilayer film is 1 N / mm or more and less than 30 N / mm in the TD direction of the film. The film for a mycelia bed cultivation bag according to [1] or [2], which is characterized by the above.
[4] In any one of the above [1] to [3], the thickness of the second layer (B) is 20 to 70% based on the thickness of the entire multilayer film. The film for a fungus bed cultivation bag as described.
[5] The first layer (A) in which the multilayer film comprises high-density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ ,
A 20% to 90% by weight cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher and a 10% to 80% by weight high density polyethylene (b2) having a density of 0.945 to 0.966 g / cm ³ . II layer (B), and
Any one of the above [1] to [4], comprising at least three layers of the third layer (C) containing high density polyethylene (c1) having a density of 0.945 to 0.966 g / cm ³ in order. The film for fungus bed cultivation bags according to claim 1.
[6] The first layer (A) in which the multilayer film comprises high-density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ and an ethylene / α-olefin copolymer (a2),
The cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher is 20 to 90% by weight, the high density polyethylene (b2) having a density of 0.945 to 0.966 g / cm ³ , and the ethylene / α-olefin copolymer. A second layer (B) comprising a polymer (b3), and a third layer comprising a high density polyethylene (c1) having a density of 0.945 to 0.966 g / cm ³ and an ethylene / α-olefin copolymer (c2). The film for fungus bed cultivation bags according to any one of [1] to [4], wherein the film has at least three layers (C) in order.
[7] In the above [6], at least one of the ethylene / α-olefin copolymers (a2), (b3) and (c2) is a metallocene catalyst-based ethylene / α-olefin copolymer. The film for a fungus bed cultivation bag as described.
[8] A fungus bed cultivation bag having a bag-like body for storing a fungus bed, which is composed of the film for a fungus bed cultivation bag according to any one of [1] to [7].
[9] A bag-like body for storing a fungus bed composed of the film for fungus-bed cultivation bags according to any one of [1] to [7], and a passage formed on at least a part of the bag-like body. A fungus bed cultivation bag having pores and a filter covering the ventilation holes.

  According to the present invention, the film for fungus bed cultivation bag and the fungus bed cultivation using the multilayer film which is excellent in the tearing property in the vertical direction and the horizontal direction and the puncture resistance and excellent in the tearing property in the vertical direction and the horizontal direction even after the heat treatment. A bag is provided and is useful for fungus bed cultivation methods such as mushroom cultivation.

FIG. 1 is a schematic view showing a cross section of an example of an easily tearable multilayer film having heat resistance used in the present invention. FIG. 2 is a schematic view showing an example of a fungus bed cultivation bag using the film for a fungus bed cultivation bag of the present invention.

  Hereinafter, the heat resistant, puncture resistant, and easily tearable film for fungus bed cultivation bag and the fungus bed cultivation bag of the present invention will be described in detail for each item.

The film for a fungus bed cultivation bag having heat resistance, puncture resistance, and easy tear of the present invention is a film for a fungus bed cultivation bag for constituting a bag-like body for storing a fungus bed in a fungus bed cultivation bag. And a multilayer film having at least three layers of the following I layer, II layer, and III layer in order.
That is, a layer I including a specific high density polyethylene, a specific amount or more of a cyclic olefin resin having a specific glass transition point, preferably a layer II including a specific high density polyethylene, and a specific high density polyethylene It has a III layer, and optionally contains an ethylene / α-olefin copolymer in the I to III layers.

  Further, the fungus bed cultivation bag of the present invention is formed on at least a part of the bag-like body constituted by the film for fungus bed cultivation bag having the heat resistance, puncture resistance, and easy tearability. And a filter that covers the vent hole.

  In the present specification, the “layer III” is a layer (hereinafter also referred to as “inner layer”) when the multilayer film is formed into a bag-like body, and the “layer I” is the multilayer film. It is a layer (hereinafter also referred to as an “outer layer”) when it is formed into a bag-like body, and “the II layer” is a layer (hereinafter referred to as “a layer” provided between the I layer and the III layer). It is also referred to as “intermediate layer”. These layers are arranged from the inside to the outside in the order of “III layer”, “II layer”, and “I layer”, but they may be in direct contact with each other, and optionally above and below each layer. Additional layers can also be provided. However, such optional additional layers must be selected so as not to interfere with the solution of the problem to be solved by the present invention.

1. Layer constituting multilayer film having heat resistance, puncture resistance and easy tearing property (1) Layer II The layer II in the film of the present invention is a cyclic olefin resin (b1) having a glass transition point of 105 ° C or higher. It is characterized by containing 20 to 90% by weight and other polyethylene resins, and in a preferred embodiment, the cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher is 20 to 90% by weight and the density is 10 to 80% by weight of 0.945 to 0.966 g / cm ³ of high density polyethylene (b2), or 20 to 90% by weight of cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher. a density of the layer containing high-density polyethylene (b2) of 0.945~0.966g / cm ³ and an ethylene · alpha-olefin copolymer (b3), preferably, the glass transition There a 20 to 90 wt% 105 ° C. or more cycloolefin resin (b1), and high density polyethylene (b2) 5 to 80 wt% of the density of 0.945~0.966g / cm ^3, ethylene · alpha-olefin It contains 0 to 65% by weight of copolymer (b3). If the cyclic olefin-based resin at 105 ° C. or higher is less than 20% by weight, it is not preferable because sufficient tearability and puncture resistance may not be obtained.

(A) Cyclic olefin resin (b1)
Examples of the cyclic olefin resin (b1) used in the second layer of the heat-resistant easily tearable film of the present invention include a norbornene polymer, a vinyl alicyclic hydrocarbon polymer, and a cyclic conjugated diene polymer. Can be mentioned. Among these, norbornene-based polymers are preferable. As the norbornene polymer, 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 ( Hereinafter, an ethylene / cyclic olefin copolymer such as “COC”) may also be used. COP and COC hydrogenated products can also be used.

  When a cyclic olefin resin and high density polyethylene are used for the II layer, the cyclic olefin resin (b1) is preferably COC because of its good 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.

  When an ethylene / cyclic olefin copolymer obtained from ethylene and a cyclic monomer is used, the ethylene / cyclic olefin copolymer has an ethylene unit / cyclic olefin unit content ratio of 15 to 40 / weight ratio. It is preferable that it is 85-60. More preferably, it is 30-40 / 70-60. If the ethylene unit is less than 15% by weight, the rigidity becomes too high, and the inflation moldability and bag-making suitability may be deteriorated. On the other hand, if the ethylene unit is 40% by weight or more, sufficient easy tearability and rigidity may not be obtained. A content ratio within this range is preferable because the film has improved rigidity, tearability, puncture resistance, processing stability, and impact strength.

  Furthermore, the ethylene / cyclic olefin copolymer preferably has a glass transition point of 105 ° C. or higher. More preferably, it is 110 degreeC or more. The glass transition point varies depending on, for example, the content ratio of ethylene units / cyclic olefin units. When the content of the cyclic olefin unit is lower than the above range, the glass transition point becomes lower than the above range. For example, easy tearability cannot be obtained after heat treatment at 120 ° C., and the barrier property of the aromatic component is reduced. There is a risk that sufficient rigidity cannot be obtained and suitability for high-speed packaging machines is poor. On the other hand, if the content of the cyclic olefin unit exceeds the above range, the glass transition point becomes too high, and the melt moldability of the copolymer and the adhesion to the olefin resin may be lowered, which is not preferable.

  Further, 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 blending ratio of the cyclic olefin resin (b1) in the resin material forming the second layer is preferably 20 to 90% by weight, more preferably 30 to 50% by weight.

  It is preferable that 10-30 weight% of cyclic olefin resin (b1) is contained on the basis of the whole easily tearable multilayer film. More preferably, it is 10-25 weight%, More preferably, it is 10-20 weight%. If it is less than 10% by weight, it is not preferable because sufficient tearability may not be obtained. On the other hand, if it is more than 30% by weight, the rigidity becomes too high, and the inflation moldability and bag-making suitability may be deteriorated.

As a commercial product that can be used as the cyclic olefin resin (b1), examples of the ring-opening polymer (COP) of the 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, TOPAS grade 7010F-600 is preferred because the content ratio of the norbornene-based monomer is in the above-mentioned preferred range and processability.
In addition, the norbornene unit content in the norbornene-based copolymer is preferably 30 mol% or more and 70 mol% or less, more preferably 35 mol% or more and 65 mol% or less, and further preferably 36 mol% or more and 60 mol% or less. If the content of norbornene units is less than 30 mol%, easy tearability may not be obtained. Moreover, when it exceeds 70 mol%, workability may deteriorate.

(B) High density polyethylene (b2)
The layer II of the heat-resistant easily tearable film of the present invention is sometimes referred to as high density polyethylene (b2, hereinafter referred to as “HDPE (b2)”) having a density of 0.945 to 0.966 g / cm ³ . ) Is included.

The high-density polyethylene (b2) is either a copolymer of ethylene and an α-olefin, or a homopolymer of ethylene and polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. However, the density needs to be 0.945 to 0.966 g / cm ³ . Preferably it is 0.950-0.960 g / cm < ³ >. When the density is less than 0.945 g / cm ³ , sufficient heat resistance cannot be obtained, and the performance may be affected such that easy tearability cannot be obtained after heat treatment. On the other hand, when the density exceeds 0.966 g / cm ³ , the rigidity of the film increases and the handling property may be inferior.

  In the present invention, the density of the polymer is a value measured based on JIS-K-6922-2.

  Moreover, it is preferable that the melt flow rate (MFR) of a high density polyethylene (b2) is 0.1-30 g / 10min in 190 degreeC. More preferably, it is 0.5-4.0 g / 10min. When the MFR is less than 0.1 g / 10 min, the melt flowability is deteriorated, film processing becomes difficult, and problems such as an increased motor load may occur. On the other hand, if it exceeds 30 g / 10 min, the melt viscosity is too low, and the film-forming stability during film processing of the composition 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.

  The high-density polyethylene (b2) used in the present invention is specifically an ethylene homopolymer or an ethylene-α-olefin copolymer. In the latter, the proportion of α-olefin units copolymerized with ethylene is usually 0.05 to 2 mol%, preferably 0.05 to 1 mol%, particularly preferably 0.1 to 1 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- Mention may be made of methylpentene-1.

  The blending ratio of the high-density polyethylene (b2) in the resin material forming the second layer is preferably 10 to 80% by weight when the ethylene / α-olefin copolymer (b3) described later is not included. , (B3) is preferably 5 to 65% by weight, more preferably 10 to 50% by weight.

(C) Ethylene / α-olefin copolymer (b3)
The layer II of the heat-resistant easily tearable film of the present invention may optionally contain an ethylene / α-olefin copolymer (b3), particularly an ethylene / α-olefin copolymer having a density of 0.94 g / cm ³ or less. A polymer is included.

The ethylene / α-olefin copolymer is a copolymer obtained by copolymerizing ethylene and an α-olefin, preferably having a density of 0.94 g / cm ³ or less, and ethylene and a carbon number of 3 to 20 , Preferably it is a copolymer with a C3-C12 alpha olefin. As the α-olefin having 3 to 20 carbon atoms, propylene, 1-butene, 4-methyl-1-pentene, 1-pentene, 1-hexene, 1-octene and the like are used. Content of the structural unit derived from a C3-C20 alpha olefin in an ethylene-alpha-olefin copolymer is 1-7 mol%, Preferably it is 2-5 mol%, More preferably, it is 2-3 mol %. When the content of the structural unit derived from the α-olefin having 3 to 20 carbon atoms exceeds 7 mol%, the impact resistance, creep resistance, and heat seal strength are lowered, and when the content is less than 1 mol%, the transparency is obtained. Decrease is observed.

  The ethylene / α-olefin copolymer is not particularly limited as long as it is as described above, but a specific ethylene / α-olefin copolymer satisfying the following requirements (a) to (c) is particularly preferable.

(A) the density of the ethylene · alpha-olefin copolymer, 0.86~0.94g / cm ^3, preferably, 0.89~0.94g / cm ^3, more preferably 0.90~0.93g / Cm ³ range. If the density is less than 0.86 g / cm ³ , rigidity (waist strength) and heat resistance may be reduced. On the other hand, if the density exceeds 0.94 g / cm ³ , pinhole resistance, tear strength, impact resistance and the like may be insufficient.

  The (b) MFR of the ethylene / α-olefin copolymer is 0.01 to 50 g / 10 minutes, preferably 0.05 to 30 g / 10 minutes, and more preferably 0.1 to 10 g / 10 minutes. . When the MFR is less than 0.01 g / 10 minutes, a decrease in fluidity (moldability of the laminate) is observed, and when it exceeds 50 g / 10 minutes, a decrease in strength is observed.

  The molecular weight distribution (Mw / Mn) of the ethylene / α-olefin copolymer is 1.5 to 4.5, preferably 2.0 to 4.0, and more preferably 2.5 to 3.0. It is a range. If Mw / Mn is less than 1.5, the moldability is inferior, and if Mw / Mn exceeds 4.5, the pinhole resistance, tear strength, impact resistance and the like are inferior. Here, the molecular weight distribution (Mw / Mn) of the ethylene / α-olefin copolymer is obtained by calculating the weight average molecular weight (Mw) and the number average molecular weight (Mn) by gel permeation chromatography (GPC). It can be obtained by calculating (Mw / Mn).

  As the ethylene / α-olefin copolymer, an ethylene / α-olefin copolymer obtained by a known method can be used, and the ethylene / α-olefin copolymer is not particularly limited by a catalyst, a production method or the like as long as the above parameters are satisfied. However, it is preferably obtained by (co) polymerizing ethylene and an α-olefin in the presence of a metallocene catalyst containing an organic cyclic compound having at least a conjugated double bond and a transition metal compound of Group 4 of the periodic table. A chain ethylene (co) polymer is desirable. Such a linear ethylene (co) polymer has a narrow molecular weight distribution and composition distribution, and therefore has excellent mechanical properties, heat sealing properties, heat blocking properties, etc., and is also a heat resistant polymer. .

  When the ethylene / α-olefin copolymer (b3) is contained in the resin material forming the second layer, the blending ratio is preferably 5 to 65% by weight, more preferably 10 to 50% by weight. is there. By setting the proportion of the ethylene / α-olefin copolymer to 5% by weight or more, the heat resistance, puncture strength, low-temperature heat sealability, heat seal strength, and mechanical strength of the laminate can be increased.

(2) Layer I In the heat-resistant easily tearable multilayer film of the present invention, the layer I is a high-density polyethylene (a1, hereinafter referred to as “HDPE (a1)) having a density of 0.945 to 0.966 g / cm ^3. "). The density of HDPE (a1) is preferably 0.950 to 0.960 g / cm ³ .

  The content of HDPE (a1) in the first layer is preferably 70% by weight or more and 100% by weight or less, more preferably 80% by weight or more and 90% by weight or less.

The high-density polyethylene (a1) is either a copolymer of ethylene and an α-olefin, or a homopolymer of ethylene and polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. However, the density needs to be 0.945 to 0.966 g / cm ³ . Preferably it is 0.950-0.960 g / cm < ³ >. When the density is less than 0.945 g / cm ³ , sufficient heat resistance cannot be obtained, and there is a possibility that performance may be affected such that easy tearability cannot be obtained after heat treatment at 120 ° C. On the other hand, when the density exceeds 0.966 g / cm ³ , the rigidity of the easily tearable film having heat resistance is increased, and the handleability may be deteriorated.

  Moreover, it is preferable that the melt flow rate (MFR) of a high density polyethylene (a1) is 0.1-30 g / 10min in 190 degreeC. More preferably, it is 0.5-4.0 g / 10min. When the MFR is less than 0.1 g / 10 min, the melt flowability is deteriorated, film processing becomes difficult, and problems such as an increased motor load may occur. On the other hand, if it exceeds 30 g / 10 min, the melt viscosity is too low, and film formation stability during film processing may be lowered, which is not preferable.

  Specifically, the high density polyethylene (a1) is an ethylene homopolymer or an ethylene-α-olefin copolymer. In the latter, the proportion of α-olefin units copolymerized with ethylene is usually 0.05 to 2 mol%, preferably 0.05 to 1 mol%, particularly preferably 0.1 to 1 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- Mention may be made of methylpentene-1.

  The layer I optionally contains an ethylene / α-olefin copolymer (a2) as another component. As (a2), those described above as the ethylene / α-olefin copolymer (b3) can be preferably used. When the ethylene / α-olefin copolymer (a2) is contained in the first layer, the content thereof is 1% by weight to 30% by weight, preferably 10% by weight to 20% by weight.

(3) Layer III The layer III in the heat-resistant easily tearable multilayer film of the present invention is a high-density polyethylene (c1, hereinafter referred to as “HDPE (c1)” having a density of 0.945 to 0.966 g / cm ^3. "). The density of HDPE (c1) is preferably 0.950 to 0.960 g / cm ³ .

  The content of HDPE (c1) in the layer III is preferably 70% by weight or more and 100% by weight or less, more preferably 80% by weight or more and 90% by weight or less.

The high-density polyethylene (c1) is a copolymer of ethylene and α-olefin, or a homopolymer of ethylene and polymerized by a metallocene catalyst, a Ziegler catalyst, a Phillips catalyst, or the like. However, the density needs to be 0.945 to 0.966 g / cm ³ . Preferably it is 0.950-0.960 g / cm < ³ >. When the density is less than 0.945 g / cm ³ , sufficient heat resistance cannot be obtained, and there is a possibility that performance may be affected such that easy tearability cannot be obtained after heat treatment at 120 ° C. On the other hand, when the density exceeds 0.966 g / cm ³ , the rigidity of the easily tearable film having heat resistance is increased, and the handleability may be deteriorated.

  Moreover, it is preferable that the melt flow rate (MFR) of a high density polyethylene (c1) is 0.1-30 g / 10min in 190 degreeC. More preferably, it is 0.5-4.0 g / 10min. When the MFR is less than 0.1 g / 10 min, the melt flowability is deteriorated, film processing becomes difficult, and problems such as an increased motor load may occur. On the other hand, if it exceeds 30 g / 10 min, the melt viscosity is too low, and film formation stability during film processing may be lowered, which is not preferable.

  From the viewpoint of dispersibility, the melt flow rate (MFR) of the high-density polyethylene (c1) is preferably higher than the melt flow rate (MFR) of the ethylene / α-olefin copolymer.

The high-density polyethylene (c1) used in the present invention is specifically an ethylene homopolymer or an ethylene-α-olefin copolymer. In the latter, the proportion of α-olefin units copolymerized with ethylene is usually 0.05 to 2 mol%, preferably 0.05 to 1 mol%, particularly preferably 0.1 to 1 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- Mention may be made of methylpentene-1.
The high-density polyethylene (a1), the high-density polyethylene (b2), and the high-density polyethylene (c1) may be different from each other or the same.

  The III layer optionally contains an ethylene / α-olefin copolymer (c2) as another component. As (c2), those described above as the ethylene / α-olefin copolymer (b3) can be preferably used. When the ethylene / α-olefin copolymer (c2) is contained in the third layer, the content thereof is 1 wt% or more and 30 wt% or less, preferably 10 wt% or more and 20 wt% or less. From the viewpoint of realizing high puncture resistance, it is preferable that an ethylene / α-olefin copolymer is contained in each of the first to third layers. The ethylene / α-olefin copolymers (a2), (b3) and (c2) may be different from each other or the same. The ethylene / α-olefin copolymers (a2), (b3) and (c2) are preferably produced with a metallocene catalyst.

  In the present invention, the anti-fogging agent, antistatic agent, thermal stabilizer, nucleating agent, antioxidant, lubricant, anti-blocking agent, mold release agent, UV absorber are applied to the I layer, II layer and III layer. Components such as a colorant, a colorant, LDPE, and LLDPE can be added as long as the object of the present invention is not impaired.

2. Lamination of I-layer, II-layer, and III-layer As described above, the I-layer to III-layer of the present invention are composed of a specific I-layer / specific II-layer / specific III-layer. Consists of. In FIG. 1, the schematic of the cross section of an example of the easily tearable multilayer film of this invention is shown. Reference numeral 1 denotes the I layer, 2 denotes the II layer, and 3 denotes the III layer.

  The total thickness of the first to third layers is preferably 30 to 150 μm. When the thickness of the multilayer film is 30 μm or more, excellent secondary formability is easily obtained.

  Moreover, it is preferable that the thickness of the II layer among the 1st layer-the III layer of this invention is 20 to 70% on the basis of the whole easily tearable multilayer film. More preferably, it is 20 to 50%. For example, the thickness ratio of the I layer / II layer / III layer can be about 1: 0.5: 1 to 1: 4: 1. If the thickness of the second layer is thinner than 20% of the whole easily tearable multilayer film, it is not preferable because sufficient tearability may not be obtained. On the other hand, if it is thicker than 70%, the rigidity becomes too high, and the inflation moldability and bag making suitability may be deteriorated. If the thickness of the second layer is in this range, it is excellent in easy tearing and advantageous in terms of cost, and the transparency, tearing property and pinhole resistance of the heat-resistant easily tearing multilayer film are improved. Therefore, it is preferable.

  The method for producing the first to third layers of the present invention is not particularly limited. For example, HDPE (a1) and ethylene / α-olefin copolymer (a2) used for the first layer, Cyclic olefin resin (b1), high-density polyethylene (b2) and ethylene / α-olefin copolymer (b3) to be used, high-density polyethylene (c1) and ethylene / α-olefin copolymer to be used for the third layer ( c2) are heated and melted in different extruders and laminated in the order of layer I / layer II / layer III in the melted state by a method such as a coextrusion multilayer die method or a feed block method, Examples thereof include a coextrusion method in which a film is formed by a T-die / chill roll method. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained. Each layer of the film of the present invention may or may not be stretched before and after lamination, but considering the balance of tear strength in length and breadth, it is substantially unstretched except for the inevitable elongation due to tension during processing. It is preferable that

3. Film for cultivating bed cultivation bag having heat resistance, puncture resistance, and easy tearing property The film for cultivating bed cultivation bag of the present invention is composed of the multilayer film having the above heat resistance and easy tearing property. In particular, after heat treatment (for example, heat sterilization treatment at 120 ° C. for 60 minutes), the Elmendorf tear strength measured according to JIS K7128-2 is in the longitudinal direction (MD direction) and the transverse direction (TD direction), respectively. It is preferable that it is 1 N / mm or more and less than 30 N / mm. More preferably, it is 20 N / mm or less. In particular, the lateral direction (TD direction) preferably satisfies this range. Further, the MD / TD ratio of the Elmendorf tear strength of the heat-treated film is preferably 1.0 ± 0.3, and more preferably 1.0 ± 0.2.

4). The fungus bed cultivation bag The fungus bed cultivation bag of the present invention is a bag used for the cultivation of mushrooms, and the film for a fungus bed cultivation bag composed of the above-mentioned multilayer film having heat resistance and easy tearability, It is a fungus bed cultivation bag used as a film for constructing a bag-like body for storing fungus beds.
As a more specific fungus bed cultivation bag, as shown in FIG. 2, the fungus bed storage bag-like body (4) composed of the film for fungus bed cultivation bag of the present invention, and the bag-like body A fungus bed cultivation bag having a vent hole (5) formed at least in part and a filter (6) covering the vent hole.
The fungus bed cultivation bag is required to have such characteristics as heat resistance that can withstand heat sterilization treatment, easy tearing ability to tear easily from any direction after heat treatment, and puncture resistance to avoid contamination with harmful bacteria. The film of the present invention has all these properties in a well-balanced manner and is suitable for fungus bed cultivation bags.

  Specifically, the form of the fungus bed cultivation bag was formed into a bag shape by using the third layer of the film for fungus bed cultivation bag of the present invention as a heat seal layer and heat-sealing the third layers. A bag-shaped packaging bag is mentioned. Cut out the two easily tearable films into the desired size of the packaging bag, overlap them and heat-seal three sides to form a bag, and then pass at least a part of the bag for ventilation. A fungus bed cultivation bag is provided by providing a pore and a filter that covers the vent hole and passes air but prevents contamination of germs. After filling the contents from one side that is not heat-sealed, it can be used as a fungus bed cultivation bag by heat-sealing and sealing. Moreover, it can use also in the form of pillow packaging using the said easily tearable film of 1 sheet. Furthermore, it is also possible to form a fungus bed cultivation bag by stacking and heat-sealing another film heat-sealable with the III layer. At that time, as another film to be used, a film such as LDPE or EVA having relatively low mechanical strength can be used. In addition, a laminate film in which a film such as LDPE or EVA and a stretched film having relatively good tearability, for example, a biaxially stretched polyethylene terephthalate film (OPET), a biaxially stretched polypropylene film (OPP), or the like, is used. Can do.

  The fungus bed cultivation bag using the film for fungus bed cultivation bag of the present invention has a V-notch, U-notch, I-notch, perforation, fineness in the seal portion in order to weaken the initial tear strength and further improve the openability. It is more preferable to form an arbitrary tear start portion such as a porous hole.

  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.

[Measuring method]
(1) Elmendorf tear strength Measured according to JIS K7128-2. In addition, MD is a flow direction (MD: Machine Direction), and TD is a value in the vertical direction (TD: Transverse Direction).

(2) Tearability evaluation by hand A test piece for trousers described in JIS K7128-1 was prepared. Slowly and intermittently teared by hand in the 180 ° direction. Even if it was torn intermittently, it was always marked as ◯, when tearing required force, it became difficult to tear immediately, and when it could not be torn intermittently, Δ, and when it was not torn at all, x.

(3) Puncture strength The maximum load until the needle is penetrated by fixing the film and piercing a semicircular needle with a diameter of 1.0 mm and a tip shape radius of 0.5 mm at a speed of 50 ± 0.5 mm per minute. (N) was measured.

[Inflation Film Molding Conditions and Formability Evaluation Method]
An inflation film was molded and evaluated under the following molding conditions using the following inflation film film forming machine (molding apparatus).

(3 types, 3 layers inflation molding machine)
Equipment: Inflation molding equipment (Placo)
Extruder screw diameter: outer layer (layer I) / intermediate layer (layer II) / inner layer (layer III) = 50 mmφ / 55 mmφ / 50 mmφ
Die diameter: 200mmφ
Extrusion amount: 60 kg / hr
Die lip gap: 3mm
Take-up speed: 17m / min Blow-up ratio: 2.0
Molding resin temperature: outer layer (I layer) / inner layer (III layer) 180 ° C., intermediate layer (II layer) 190 ° C.
Film thickness: 50 μm
Cooling ring: Two-stage air cooling ring

[Raw materials]
The raw materials used in the examples are as follows. The unit of density is g / cm ³ and the unit of MFR is g / 10 minutes.
(1) High-density polyethylene Novatec HD “HY444” manufactured by Nippon Polyethylene
High density polyethylene (2) COC (i) with a density of 0.956 g / cm ³ and an MFR of 1.1 g / 10 min
Product name TOPAS "7010F-600" is used.
Norbornene content 42mol%, glass transition point 110 ℃
(3) COC (ii)
The product name TOPAS “8007F-600” is used.
Norbornene content 36mol%, glass transition point 78 ℃
(4) Ethylene / α-olefin copolymer (i)
"NF366A" made by Nippon Polyethylene
Density 0.919 g / cm ³ , MFR 1.5 g / 10 min ethylene / α-olefin copolymer (5) Ethylene / α-olefin copolymer (ii)
“NF324A” manufactured by Nippon Polyethylene
An ethylene / α-olefin copolymer having a density of 0.906 g / cm ³ and an MFR of 1.0 g / 10 min.

[Examples and Comparative Examples]
Example 1
As shown in Table 1, an inflation film having a layer ratio of 1: 1: 1 was obtained with the layer I as HY444, the layer II as HY444, a mixture of COC (i), and the layer III as HY444. The film thickness was 50 μm.

  The film was evaluated for Elmendorf tear strength and hand tearability. The evaluation results are shown in Table 1.

  Moreover, the said film was exposed to the conditions of 120 degreeC using oven for 60 minutes. The film after the exposure was evaluated for Elmendorf tear strength and tearability by hand. The evaluation results are shown in Table 1.

(Examples 2 and 3)
Evaluation was performed in the same manner as in Example 1 except that the blending ratio of the second layer was changed. The evaluation results are shown in Table 1.

(Comparative Examples 1-3)
As shown in Table 1, an inflation film was obtained and evaluated in the same manner as in Examples 1 to 3.
Example 4
As shown in Table 1, layer I was a mixture of HY444 (84 wt%) and NF366A (16 wt%), layer II was HY444 (35.7 wt%), COC (i) (34.3 wt%) and A mixture of NF342A (30% by weight), layer III as HY444 (84% by weight) and NF366A (16% by weight) gave an inflation film with a layer ratio of 1: 1: 1. The film thickness was 50 μm. About the obtained film, the puncture strength was evaluated by the said method about Elmendorf tear strength and the tearability by hand similarly to Examples 1-3. The evaluation results are shown in Table 1.

(Example 5)
A film was prepared and evaluated in the same manner as in Example 4 except that the blending ratio of the first layer and the third layer was changed to HY444 (76% by weight) and NF366A (24% by weight). The evaluation results are shown in Table 1.

(Comparative Example 4)
As shown in Table 1, an inflation film was obtained and evaluated in the same manner as in Example 4 except that COC (ii) (glass transition point 78 ° C.) was used as the cyclic olefin resin.

[Evaluation]
As is clear from Table 1, the films of Examples 1 to 5 having a specific layer structure that is a specific matter of the invention of the present invention have sufficient tearability because the tear strength is low even after heat treatment, and is high. The piercing strength is obtained. Therefore, it is suitable as a film for a fungus bed cultivation bag that performs heat sterilization at a high temperature. On the other hand, the film of Comparative Example 1 had high transverse Elmendorf tear strength even when unheated, and the films of Comparative Examples 2 to 4 had easy tearability before heat treatment, but the transverse Elmendorf tear after heat treatment. The strength is increased and the easy tearability is impaired.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in the tearability of the vertical direction and a horizontal direction, and the film for fungus bed cultivation bags excellent in tearability after heat processing, and a fungus bed cultivation bag using the same are provided. Therefore, it is very useful industrially.

DESCRIPTION OF SYMBOLS 1 1st layer 2 2nd layer 3 3rd layer 4 Bag-like body 5 Vent hole 6 Filter

Claims (9)

It is a film for a fungus bed cultivation bag for constituting a bag-like body for storing a fungus bed,
Layer I (A) containing high-density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ , and cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher of 20 to 90% by weight A layer II (B) containing another polyethylene resin, and a layer III (C) containing a high-density polyethylene (c1) having a density of 0.945 to 0.966 g / cm ³ in this order. A film for fungus bed cultivation bags, which is a multilayer film.   The said cyclic olefin resin (b1) is an ethylene and cyclic olefin copolymer, The film for fungus bed cultivation bags of Claim 1 characterized by the above-mentioned.   The Elmendorf tear strength measured in accordance with JIS K7128-2 after heat treatment at 120 ° C. for 60 minutes of the multilayer film is 1 N / mm or more and less than 30 N / mm in the TD direction of the film. The film for fungus bed cultivation bags according to claim 1 or 2.   The fungal bed cultivation according to any one of claims 1 to 3, wherein the thickness of the second layer (B) is 20 to 70% based on the thickness of the entire multilayer film. Film for bags. Layer I (A), wherein the multilayer film comprises high density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ ;
A 20% to 90% by weight cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher and a 10% to 80% by weight high density polyethylene (b2) having a density of 0.945 to 0.966 g / cm ³ . II layer (B), and
It has at least 3 layers of the III layer (C) containing the high density polyethylene (c1) whose density is 0.945-0.966 g / cm < ³ > in order, The any one of Claims 1-4 characterized by the above-mentioned. Film for fungus bed cultivation bag as described in 4. Layer I (A), wherein the multilayer film comprises high density polyethylene (a1) having a density of 0.945 to 0.966 g / cm ³ and an ethylene / α-olefin copolymer (a2),
The cyclic olefin resin (b1) having a glass transition point of 105 ° C. or higher is 20 to 90% by weight, the high density polyethylene (b2) having a density of 0.945 to 0.966 g / cm ³ , and the ethylene / α-olefin copolymer. A second layer (B) comprising a polymer (b3), and a third layer comprising a high density polyethylene (c1) having a density of 0.945 to 0.966 g / cm ³ and an ethylene / α-olefin copolymer (c2). It has at least 3 layers of a layer (C) in order, The film for fungal bed cultivation bags of any one of Claims 1-4 characterized by the above-mentioned.   The fungus bed according to claim 6, wherein at least one of the ethylene / α-olefin copolymers (a2), (b3) and (c2) is a metallocene catalyst-based ethylene / α-olefin copolymer. Film for cultivation bags.   A fungus bed cultivation bag having a bag-like body for storing a fungus bed, which is constituted by the film for a fungus bed cultivation bag according to any one of claims 1 to 7.   A bag-shaped body for storing a bacterial bed composed of the film for a bacterial bed cultivation bag according to any one of claims 1 to 7, and a vent formed in at least a part of the bag-shaped body, A fungus bed cultivation bag having a filter covering the vent hole.