Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
  • B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/24—All layers being polymeric
  • B32B2250/242—All polymers belonging to those covered by group B32B27/32
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
  • B32B2307/31—Heat sealable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/702—Amorphous
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/04—Polyethylene
  • B32B2323/046—LDPE, i.e. low density polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging

Definitions

• the present invention relates to a polyolefin-based unstretched multilayer film. Specifically, it has excellent optical properties such as high transparency, high glossiness, high image clarity, blocking resistance, and low temperature heat seal properties.
• the present invention relates to a polyolefin-based unstretched multilayer film excellent in heat seal strength when bonded to a base film to form a composite film; sealing performance; tear-opening property or easy peel property of a package.
• Polyolefin resin films are widely used as materials for packaging various products. For example, food packaging applications; textile goods / garments daily goods packaging applications; industrial parts packaging applications.
• polypropylene resin films are widely used because they are excellent in rigidity and heat resistance, and have a high feeling of elasticity.
• the polypropylene resin film is not sufficient in at least heat sealability, particularly low temperature heat sealability, and impact resistance.
• attempts have been made to improve heat sealability and impact resistance by copolymerizing film material polypropylene.
• a significant effect has not been obtained particularly with respect to impact resistance at low temperatures.
• blocking problems occur when trying to improve heat sealability. For this reason, the above attempts to form a copolymer have not been successful.
• a linear ethylene- ⁇ -olefin copolymer (LLDPE) is used as an intermediate layer, and the intermediate layer and a polypropylene resin layer as both outer layers are laminated.
• LLDPE linear ethylene- ⁇ -olefin copolymer
• the tear strength when the laminated film is bonded to a base film to obtain a composite film becomes very high, the tear-opening property when this is used as a packaging material is significantly impaired.
• JP-A-2004-276373 discloses a polyolefin-based multilayer film having improved low-temperature heat sealability and blocking resistance by laminating a specific polypropylene-based polymer as both outer layers and an LLDPE layer as an intermediate layer. Proposed. Even with this technique, the tear strength of the resulting composite film is very high, and the tear-openability when this film is used as a packaging material is not satisfactory. By the way, in food packaging applications, particularly packaging of snacks, etc., there is a demand to peel off the heat seal portion and open the package in addition to the above-described tear opening at the time of opening.
• the present invention has been made in view of the present state of the art as described above.
• the object of the present invention is excellent in various properties such as optical properties, blocking resistance, low-temperature heat sealability, heat seal strength, and sealability, as well as polyolefin-based non-stretching that is excellent in tear-opening properties and easy peel properties of the package. It is to provide a multilayer film.
• a polyolefin-based unstretched multilayer film having a laminate layer as an outermost layer, at least one intermediate layer, and a heat seal layer as another outermost layer
• the laminate layer is made of a polyolefin resin
• At least one of the intermediate layers is made of a polyolefin resin containing long-chain branched LLDPE
• the heat seal layer is made of a polyolefin resin containing a polypropylene resin
• the polyolefin resin of the laminate layer has a higher melting point than the polypropylene resin in the heat seal layer
• the long-chain branched LLDPE in the polyolefin-based resin in the intermediate layer is The ratio Mw / Mn of polystyrene-equivalent weight average molecular weight Mw and number average molecular weight Mn measured by gel permeation chromatography is 7.5 to 15.0, The amount of non-crystalline components measured by the temperature rising elution fraction
• the polyolefin-based unstretched multilayer film of the present invention has a laminate layer that is the outermost layer, at least one intermediate layer, and a heat seal layer that is the other outermost layer.
• the laminate layer in the multilayer film of the present invention is made of a polyolefin resin.
• the polyolefin resin has a higher melting point than the polypropylene resin in the heat seal layer described later.
• the melting point of the polyolefin resin is preferably 3 ° C. or higher, more preferably 5 ° C. or higher, and further preferably 15 ° C. higher than the melting point of the polypropylene resin in the heat seal layer. Thereby, sufficient heat resistance can be obtained in the production, lamination, heat sealing, etc.
• the difference between the melting point of the polyolefin resin and the melting point of the polypropylene resin in the heat seal layer is preferably kept at 20 ° C. or lower. This is because if the melting point difference becomes excessively large, curling may occur in the multilayer film.
• the polyolefin resin constituting the laminate layer in the present invention include a polypropylene resin, an ethylene homopolymer, an ethylene- ⁇ -olefin copolymer, and a thermoplastic elastomer. These may be used alone or in admixture of two or more. These polyolefin resins preferably have a melting point in the range of 120 to 165 ° C.
• melt flow rate MFR in the range of 1 to 30 g / 10 minutes.
• the melting point is the peak top temperature (Tm) of the maximum endothermic peak in a differential scanning calorimeter (DSC) chart;
• the MFR is a value measured according to JIS K 7210 (both melting point and MFR are the same in the present specification).
• the copolymer component for example, ethylene and ⁇ -olefin are preferable, and specifically, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene. 4-methyl-1-pentene can be used, and one or more selected from these can be used.
• the proportion of the copolymer component in this polypropylene resin is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less.
• the said ethylene-alpha-olefin copolymer does not include what corresponds to said polypropylene resin.
• Examples of the ⁇ -olefin which is a copolymerization component in the ethylene- ⁇ -olefin copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1- Examples include decene and 4-methyl-1-pentene, and one or more selected from these can be used.
• the proportion of the ⁇ -olefin component in the ethylene- ⁇ -olefin copolymer is preferably 1 to 20 mol%, more preferably 5 to 15 mol%.
• the polyolefin resin in the laminate layer of the multilayer film of the present invention preferably contains a polypropylene resin as described above.
• the laminate layer may consist only of a polypropylene resin, and may contain other polymers together with the polypropylene resin.
• the other polymer used here is preferably selected from the above-mentioned ethylene homopolymer, ethylene- ⁇ -olefin copolymer, and thermoplastic elastomer.
• the content of the other polymer is preferably 10% by weight or less, more preferably 5% by weight or less, and most preferably no other polymer based on the whole polyolefin resin. .
• the laminate layer of the multilayer film of the present invention includes, as an optional additive, for example, a heat stabilizer, a processing stabilizer, a lubricant, a nucleating agent, an antistatic agent, an antifogging agent, An antiblocking agent, antioxidant, a ultraviolet absorber, a pigment etc. can be mentioned.
• a heat stabilizer for example, a heat stabilizer, a processing stabilizer, a lubricant, a nucleating agent, an antistatic agent, an antifogging agent, An antiblocking agent, antioxidant, a ultraviolet absorber, a pigment etc.
• additives may be added by a method of directly blending with the polymer constituting the polyolefin resin, or may be added by a method of blending these additives as a master batch containing a high concentration.
• the base resin for the masterbatch any of the above polyolefin resins can be used.
• the proportion of the optional component as described above is preferably 10% by weight or less, and more preferably 5% by weight or less, based on the entire polyolefin resin. Most preferably, it does not contain such an optional component.
• the thickness of the laminate layer in the multilayer film of the present invention is preferably 1.0 to 30 ⁇ m, more preferably 2.5 to 25 ⁇ m. By setting the thickness of the laminate layer within this range, the resulting multilayer film and composite film are preferable in that high impact resistance can be obtained without impairing heat resistance and openability.
• ⁇ Intermediate layer> At least one of the intermediate layers in the multilayer film of the present invention is made of a polyolefin resin containing long-chain branched LLDPE (B1).
• the long chain branched LLDPE (B1) in the present invention is a linear low density polyethylene having a branch having 8 or more carbon atoms.
• the LLDPE used in the prior art film is common to the long chain branched LLDPE (B1) and LDPE (low density polyethylene) in the present invention in that it is a low density polyethylene having a branch.
• the long-chain branched LLDPE (B1) in the present invention is different from LLDPE and LDPE in the prior art at least in the content of long-chain branches, Mw / Mn and the amount of non-crystalline components.
• the long chain branched LLDPE (B1) in the present invention is 13
• the number of branches having 8 or more carbon atoms measured by C-NMR is 1.5 to 5.0 per 1,000 carbon atoms. This value is preferably 2.0 to 5.0, and more preferably 2.5 to 4.5.
• LLDPE having such a long chain branch when the multilayer film of the present invention is used as a package, it is possible to obtain an advantage that both tear opening and easy peel properties are compatible.
• the LLDPE in the prior art is dominant when the number of carbon atoms in the branch is 6 or less, and even if there is a branch having 8 or more carbon atoms, the amount thereof is small, usually per 1,000 carbon atoms. 1 or less, and at most 2 or less.
• the long-chain branched LLDPE (B1) in the present invention is 13 It can be distinguished from LLDPE and LDPE in the prior art by the amount of branching of 8 or more carbon atoms measured by C-NMR.
• the branched structure of long-chain branched LLDPE (B1) in the present invention and the branched structure of LLDPE in the prior art are: 13 The following describes how it is measured on C-NMR.
• the second methylene carbon from the branch end attention is paid to the second methylene carbon from the branch end, and it is determined whether or not the number of branched carbons is 8 or more by the chemical shift.
• the C-NMR measurement can be performed under the following conditions using an appropriate nuclear magnetic resonance analyzer such as a model “JNM-ECS400” manufactured by JEOL.
• the long chain branched LLDPE (B1) in the present invention has a ratio Mw / Mn (molecular weight distribution) of the weight average molecular weight Mw and the number average molecular weight Mn in terms of polystyrene measured by gel permeation chromatography (GPC) of 7.5 to 15.0. This value is preferably 8.5 to 14.5, and more preferably 9.5 to 13.5.
• the long-chain branched LLDPE (B1) in the present invention has a polystyrene-equivalent weight average molecular weight Mw measured by GPC of preferably 80,000 to 150,000, more preferably 90,000 to 140,000. preferable.
• the long-chain branched LLDPE (B1) in the present invention has an amorphous component amount of 1 to 4% by weight measured by a temperature rising elution fractionation method. In the temperature rising elution fractionation method, a solution obtained by dissolving a polymer sample in a predetermined solvent at a high temperature is supplied to a TREF (Temperature Rising Elution Fractionation) column, and then cooled to precipitate and adsorb the polymer sample in the column.
• TREF Tempoture Rising Elution Fractionation
• the column temperature is gradually raised and the eluted fraction is analyzed.
• the supply of the solvent is started, and the fraction eluted during the period in which the column temperature is maintained at 0 ° C. is used as an amorphous component. Is evaluated as the amount of non-crystalline component.
• the amount of the amorphous component of the long chain branched LLDPE is preferably 1.5 to 3.0% by weight.
• Such a temperature rising elution fractionation method can be performed, for example, using an appropriate temperature rising elution fractionation (TREF) apparatus such as a special TREF apparatus manufactured by Senshu Kagaku Co., Ltd.
• TEZ temperature rising elution fractionation
• the long-chain branched LLDPE (B1) in the present invention as described above may be synthesized by any method as long as it satisfies the above requirements. For example, it can be produced by a method using a known Ziegler-Natta catalyst, preferably together with an appropriate donor compound; a method using a Phillips catalyst; a method using a metallocene catalyst.
• the metallocene catalyst is a catalyst comprising a metallocene-type transition metal compound having at least one, preferably two, substituted or unsubstituted cyclopentadienyl ligands and a co-catalyst.
• the cocatalyst include organoaluminum compounds; complexes of organoboron compounds and cations; ion-exchange silicates and the like, and one or more selected from these can be used.
• the metallocene catalyst may be supported on a suitable inorganic substance.
• the at least one layer of the intermediate layer in the multilayer film of the present invention may contain other polymers in addition to the long-chain branched LLDPE (B1) as described above.
• examples of other polymers that can be used here include polypropylene resin (B2), polyethylene (B3) other than long-chain branched LLDPE (B1), and thermoplastic elastomer.
• polypropylene resin (B2) for example, a resin similar to the resin described above can be used for the polypropylene resin as the polyolefin resin constituting the laminate layer.
• polyethylene (B3) other than long-chain branched LLDPE (B1) examples include HDPE, LLDPE, and LDPE.
• At least one resin selected from the group consisting of polyethylene (B3) other than the polypropylene-based resin (B2) and the long-chain branched LLDPE (B1) among the other polymers described above is used as the intermediate layer in the multilayer film of the present invention.
• the easy peel strength when the multilayer film is used as a package can be adjusted, which is preferable.
• the polyolefin resin in the at least one layer of the intermediate layer of the multilayer film of the present invention is: Consists of long-chain branched LLDPE (B1) only, or Long-chain branched LLDPE (B1); It is preferable to consist of at least one resin selected from the group consisting of polypropylene (B2) and polyethylene (B3) other than the long-chain branched LLDPE (B1) as described above.
• the at least one layer of the intermediate layer of the multilayer film of the present invention preferably comprises only the polyolefin resin as described above and does not contain any other resin.
• the polyolefin resin in the at least one layer of the intermediate layer of the multilayer film of the present invention preferably contains the above resins in the following proportions.
• Long chain branched LLDPE (B1) preferably 40% by weight or more, more preferably 50% by weight or more
• Polypropylene resin (B2) preferably 30% by weight or less, more preferably 25% by weight or less
• Polyethylene (B3) other than long-chain branched LLDPE (B1) preferably 50% by weight or less, more preferably 30% by weight or less
• the total of the polyethylene (B3) other than the long chain branched LLDPE (B1), the polypropylene resin (B2) and the long chain branched LLDPE (B1) is 100% by weight.
• the intermediate layer of the multilayer film of the present invention may contain additives as described as optional components of the laminate layer in the same manner.
• the intermediate layer in the multilayer film of the present invention may consist of only one layer, or may be a laminate of two or more layers. In the latter case, each layer constituting the intermediate layer is selected from the polyolefin resins as described above.
• the polyolefin resin constituting each layer may be the same in the type of polyolefin resin, the presence or absence of other optional polymers and additives, and the type and content thereof. One or more of may be different.
• the thickness of the intermediate layer is preferably 5 to 80 ⁇ m, more preferably 10 to 50 ⁇ m.
• the intermediate layer By setting the intermediate layer to a thickness in this range, it is preferable in terms of obtaining high impact resistance and excellent image clarity in the obtained multilayer film and composite film without impairing rigidity when a multilayer film is obtained.
• the intermediate layer is composed of a laminate of polyolefin resin
• the number of layers is preferably 2 to 4 layers, and more preferably 2 to 3 layers.
• the polyolefin resin in each layer may be the same or different.
• the thickness of the laminate is preferably within the above range as the thickness of the intermediate layer.
• the thickness of each layer constituting the laminate is preferably 2 to 40 ⁇ m, and more preferably 5 to 25 ⁇ m.
• the heat seal layer in the multilayer film of the present invention is made of a polyolefin resin containing a polypropylene resin.
• This polypropylene resin preferably contains a polypropylene resin containing 70% by weight or more of the propylene-ethylene copolymer (C).
• the polymer in the polypropylene resin of this heat seal layer may consist only of the propylene-ethylene copolymer (C), and contains other polymers together with the propylene-ethylene copolymer (C). May be.
• the composition of the propylene-ethylene copolymer (C) in the polypropylene resin of the heat seal layer is such that the resulting multilayer film and composite film have blocking resistance, low temperature heat seal property, heat seal part strength and heat seal part resistance. Contributes to improved pinhole properties.
• the proportion of the propylene-ethylene copolymer (C) in the polypropylene resin of the heat seal layer is less than 70% by weight, the degree of the above effect is insufficient, which is not preferable.
• the proportion of the propylene-ethylene copolymer (C) in the polypropylene resin of the heat seal layer is preferably 80% by weight or more, more preferably 90% by weight or more.
• the propylene-ethylene copolymer (C) preferably has a molecular weight distribution Mw / Mn represented by a ratio of the weight average molecular weight Mw to the number average molecular weight Mn, preferably 1.5 to 3.5, more preferably 1 8 to 3.2, and more preferably 2.0 to 3.0. If the Mw / Mn of the propylene-ethylene copolymer (C) is less than 1.5, the melt tension becomes too low and the film forming property tends to be inferior. On the other hand, it is preferable that Mw / Mn is 3.5 or less from the viewpoint of securing blocking resistance when a multilayer film is formed and securing optical properties in the multilayer film and the composite film.
• the propylene-ethylene copolymer (C) preferably has a Mw of 450,000 to 100,000, more preferably 400,000 to 200,000.
• the propylene-ethylene copolymer (C) preferably has a melt flow rate MFR measured at 230 ° C. and a load of 2.16 kg in accordance with JIS K 7210, preferably 1 to 30 g / 10 minutes, more preferably 5 ⁇ 15 g / 10 min. If the MFR is less than 1 g / 10 min, the melt viscosity is too high, so that the pressure in the film forming machine (for example, an extruder) becomes excessively high during the production of the multilayer film, and the productivity is reduced. It may cause poor appearance such as uniformity and melt fracture.
• the propylene-ethylene copolymer (C) preferably has a melting point of 120 to 140 ° C, more preferably 120 to 135 ° C.
• the propylene-ethylene copolymer (C) having a melting point at a temperature in this range is excellent in balance between heat resistance when producing a multilayer film and transparency when formed into a multilayer film or a composite film. This is preferable.
• the content of ethylene units in the propylene-ethylene copolymer (C) is preferably 1 to 10 mol%, more preferably 2 to 5 mol%. By setting the content ratio of the ethylene unit within this range, the resulting multilayer film can exhibit excellent blocking resistance without impairing transparency, which is preferable.
• the propylene-ethylene copolymer (C) is preferably polymerized using a metallocene catalyst, and the propylene-ethylene copolymer (C) polymerized using a metallocene catalyst is a multilayer obtained.
• the film is preferable in that it exhibits a high degree of blocking resistance and exhibits excellent optical properties when formed into a multilayer film and a composite film.
• the metallocene catalyst is a catalyst comprising a metallocene-type transition metal compound having at least one, preferably two, substituted or unsubstituted cyclopentadienyl ligands and a co-catalyst.
• the cocatalyst include organoaluminum compounds; complexes of organoboron compounds and cations; ion-exchange silicates and the like, and one or more selected from these can be used.
• the metallocene catalyst may be supported on a suitable inorganic substance. Metallocene catalysts are already known in the art, and those skilled in the art can appropriately select and use an appropriate metallocene catalyst according to the purpose.
• a polypropylene resin other than the propylene-ethylene copolymer (C) ( A1) is preferably used as the other polymer.
• the molecular weight distribution Mw / Mn represented by the ratio of the weight average molecular weight Mw and the number average molecular weight Mn is preferably 4 or more, more preferably 4.5 to 10, and still more preferably. Is 5-8.
• the tear strength of the resulting multilayer film and the composite film produced using the multilayer film is excessively high, and there is an effect of improving the tear openability in the packaging material. It will be difficult to express. This is considered to be due to the fact that when Mw / Mn is less than 4, melt orientation hardly occurs during the production of the multilayer film. On the other hand, it is preferable that Mw / Mn be 10 or less from the viewpoint of securing the melt resistance during the production of the multilayer film within an appropriate range and ensuring the blocking resistance when the multilayer film is formed.
• the polypropylene resin (A1) preferably has a Mw of 450,000 to 100,000, more preferably 400,000 to 200,000.
• the weight average molecular weight Mw and the number average molecular weight Mn are both values in terms of polystyrene measured by gel permeation chromatography (GPC).
• the polypropylene resin (A1) preferably has a melt flow rate MFR measured at 230 ° C. under a load of 2.16 kg in accordance with JIS K 7210 at 1 to 30 g / 10 minutes, and 5 to 15 g / 10 minutes. It is more preferable. If the MFR is less than 1 g / 10 min, the melt viscosity is too high, so that the pressure in the film forming machine (for example, an extruder) becomes excessively high during the production of the multilayer film, resulting in a decrease in productivity and a decrease in film thickness.
• the polypropylene resin (A1) preferably has a melting point of 120 to 150 ° C, more preferably 130 to 145 ° C.
• the polypropylene resin (A1) exhibiting a melting point at a temperature within this range is preferable in that the balance between the heat resistance when producing the multilayer film and the transparency when formed into the multilayer film and the composite film is excellent. .
• the polypropylene resin (A1) may be a propylene homopolymer or a copolymer of propylene and a copolymer component.
• the copolymerization component used here ethylene and ⁇ -olefin are preferable. Specifically, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene and the like can be mentioned, and one or more selected from these can be used.
• the proportion of the copolymer component in the polypropylene resin (A1) is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 3 mol% or less. It is preferable that a heat seal layer consists only of the said propylene-ethylene copolymer (C), or consists only of a propylene-ethylene copolymer (C) and a polypropylene resin (A1).
• the heat seal layer of the multilayer film of the present invention may contain additives as described as optional components of the laminate layer in the same manner.
• the thickness of the heat seal layer in the multilayer film of the present invention is preferably 2 to 30 ⁇ m, more preferably 2.5 to 25 ⁇ m.
• the resulting multilayer film and composite film are preferable in that high impact resistance can be obtained without impairing low-temperature heat sealability and pinhole resistance.
• the thickness of the polyolefin-based unstretched multilayer film of the present invention can be appropriately set depending on the use mode and application.
• the use mode is a selection of whether to use the multilayer film of the present invention as it is as a packaging material, or to use it as a composite film by laminating with a film substrate, The use refers to the type and weight of the contents of the packaging material.
• the thickness of the polyolefin-based unstretched multilayer film of the present invention can be, for example, 10 to 200 ⁇ m, preferably 15 to 150 ⁇ m, and more preferably 18 to 100 ⁇ m.
• Method for producing polyolefin-based unstretched multilayer film> The multilayer film of the present invention can be produced by any method as long as the method does not substantially involve stretching. “Substantially no stretching” does not mean that even a slight orientation occurs in the film manufacturing process, but means that the film does not go through an explicit stretching process. Therefore, for example, it should be understood that a slight orientation in the extrusion direction is allowed when an extrusion process under the conditions normally employed is employed.
• an appropriate method such as an extrusion method or a casting method can be employed.
• the resin constituting each layer of the multilayer film of the present invention has an appropriate MFR, and is highly compatible with a melt-type film forming machine. It is preferable because it can be expressed to the limit.
• a T die, an annular die, or the like can be used as the die for the extrusion method. However, from the viewpoint of precisely controlling the thickness of the layer to obtain excellent optical characteristics, it is not preferable to use an annular die, and it is preferable to use a T die or the like.
• the multilayer film of the present invention has a laminate layer, at least one intermediate layer, and a heat seal layer, it has a multilayer structure composed of at least three layers.
• a known method such as a co-extrusion method or an in-line laminating method can be employed.
• the coextrusion method include a multi-manifold method and a feed block method.
• the coextrusion method is preferably used because the thickness of each layer can be uniformly controlled in the width direction.
• the multilayer film of the present invention is expected to be applied as a packaging material as it is or in the form of a composite film obtained by laminating it with a film substrate.
• the film base material is affixed on the outermost layer surface, usually on the surface of the laminate layer.
• a surface treatment may be performed inline or offline on the outermost layer surface, usually on the surface of the laminate layer. Examples of the surface treatment include corona discharge treatment, flame or flame treatment.
• the composite film of the present invention is excellent in low temperature heat sealability, heat seal strength, and pinhole resistance of the heat seal portion, and is also excellent in tear openability when used as a packaging material.
• Film substrate As a material which comprises the film base material in the composite film of this invention, it can determine suitably according to the use of a packaging material. Examples thereof include a resin selected from the group consisting of a polypropylene resin, a polyethylene resin, a polyethylene terephthalate resin, and a polyamide resin, or a metal.
• the film substrate can be a layer containing one or more materials selected from these, or can be a laminate comprising a plurality of such layers.
• the thickness of the film substrate is arbitrary depending on the use of the packaging material, but can be, for example, 5 to 75 ⁇ m, and preferably 10 to 50 ⁇ m.
• the total thickness of the composite film of the present invention can be arbitrarily set according to the use of the packaging material, but can be, for example, 15 to 250 ⁇ m, preferably 20 to 200 ⁇ m, more preferably 23 to 150 ⁇ m. It is.
• ⁇ Production method of composite film> The manufacturing method of a composite film will not be specifically limited if it is a method which can affix the multilayer film of this invention on the film base material by using the lamination layer side as a sticking surface.
• Adhesion between the film substrate and the laminate layer of the multilayer film may be performed by an appropriate adhesive or thermocompression bonding.
• the adhesive used here a commercially available adhesive may be used, or a molten resin such as a molten polyethylene resin may be used.
• the method for applying the adhesive include transfer means such as gravure, gravure reverse, and offset; scraping means such as a bar and a comma bar.
• the method of laminating the film base material and the multilayer film with an adhesive layer as required include a dry lamination method and a thermal lamination method.
• Tear strength As an index of tear resistance, tear strength was measured under the following conditions using an autograph (model number: AG-500D) manufactured by Shimadzu Corporation in accordance with JIS K 7128-1. Test piece dimensions: Long side (vertical) 100 mm, short side (horizontal) 50 mm Slit: 20 mm long notch provided parallel to the long side at the center of one short side of the test piece (position 25 mm from the long side) Tensile speed: 500 mm / min Measuring temperature: 23 ° C.
• Heat seal strength As an index of heat sealability, the heat seal layers of two composite films were brought into contact with each other, and the strength when heat sealed at each temperature was examined by the following tensile test.
• the composite film is cut into a 15 mm ⁇ 200 mm rectangle, and the two sheets are stacked together so that the heat seal layers are in contact with each other, and heated under the following conditions using a YSS heat sealer manufactured by Yasuda Seiki Seisakusho Co., Ltd.
• a test piece was obtained by sealing.
• Seal bar width 5mm
• Seal pressure 0.1 MPa Sealing time: 1.0 second Sealing temperature: Variable to 150 ° C., 160 ° C. and 170 ° C.
• a “longitudinal” direction test piece the case where the long side of the rectangle coincides with the extrusion direction of the film
• a “lateral” direction test piece the case where the long side of the rectangle is orthogonal to the film extrusion direction.
• a tensile test was performed under the condition of minutes, and the maximum value of the stress was examined. If the maximum value of the stress is 3 N / 15 mm or more, it can be evaluated that sufficient heat seal strength is obtained at the temperature; If it is 13 N / 15 mm or less, it can be evaluated that it has easy peel properties.
• Easy peel sensor test
• a sensory test was conducted in which the package was opened by human hands. Using a vertical pillow packaging machine (model “TWX1N”, manufactured by Tokyo Automatic Machinery Co., Ltd.), the heat seal layers of the composite film are heat-sealed under the following conditions to obtain a 120 mm long and 100 mm wide package. It was.
• the four sides of the pseudo bag-making body are heat-sealed to the ends.
• Heat sealing temperature 160 ° C
• Seal pressure 0.1 MPa
• Heat sealing time 1.0 seconds
• Seal width 5 mm
• a cut of 10 mm is made in the vertical direction from the end portion using a cutter in a piece of the heat seal portion of the obtained pseudo bag-making body, and the cut portion is formed in the lateral direction (parallel to the surface of the pseudo-bag-making body and the cut). Tearing by hand in the direction perpendicular to the direction), the force required for the tearing and the state of the tearing portion were examined, judged according to the following criteria, and evaluated by the following calculation formula.
• the composite film was cut into a rectangle of 150 mm ⁇ 100 mm and folded back into two at the center of the short side so that the heat seal layer was inside.
• One side of the short side part is left as an opening, and the remaining two sides (one side part and the long side of the short side) are manufactured by Yasuda Seiki Seisakusho Co., Ltd., using a YSS heat sealer. Heat sealed under conditions to obtain an envelope-like pseudo bag-making body.
• Heat sealing temperature 160 ° C Seal pressure: 0.1 MPa Heat sealing time: 1.0 seconds Seal width 5mm From the opening of this pseudo bag-making body, Taseto Co., Ltd., dyeing penetrant flaw detection agent, “permeating liquid FP-S standard type” is sprayed, and the liquid leakage state from the seal part is visually observed. Evaluated by criteria.
• the main agent product number: TM-595) 15 g, a curing agent (product number: CAT-56) 2.7 g and a solution obtained by mixing 36.8 g of ethyl acetate were applied with an applicator (2 mil setting), 80 Dry at 1 ° C. for 1 minute.
• a laminate film of the polyolefin-based unstretched multilayer film obtained above was laminated on this adhesive layer while pressing with a hand roller, and then aged at 40 ° C. for 3 days to obtain a composite film.
• the unit “mil” means 0.001 inch, and 1 mil corresponds to about 25.3999 ⁇ m.
• the above (7) to (10) were evaluated. The evaluation results are shown in Table 5.
• Example 2 to 10 and Comparative Examples 1 to 4 the polyolefin-based unstretched multilayer was prepared in the same manner as in Example 1 except that the type and amount of resin supplied to the extruder for each layer were as shown in Table 3 and Table 4, respectively. Films and composite films were produced and evaluated respectively. The evaluation results are shown in Tables 5 and 6. In addition, the abbreviation of the resin raw material in Table 3 and Table 4 has the following meaning, respectively.
• the numerical value in the MFR column of Table 7 is the melt flow rate measured at a load of 2.16 kg in accordance with JIS K 7210.
• the measurement temperature was 190 ° C. for the polyethylene resin and 230 ° C. for the polypropylene resin.
• the melting point is the peak temperature of the melting point measured by a differential scanning calorimeter (DSC).
• the content of the long chain branch shown in the “long chain branch” column is the number of carbon atoms per 1,000 carbon atoms, calculated according to the following formula (2) from the result of 13 C-NMR measured under the following conditions: The number of branches of 8 or more. [ 13C -NMR measurement conditions] Measuring device: Model “JNM-ECS400” manufactured by JEOL Ltd.

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• 2014
  • 2014-12-05 WO PCT/JP2014/082906 patent/WO2015087990A1/ja active Application Filing
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