Laminated sealant film

Abstract

Provided is a polypropylene-based laminated sealant film in which interlayer separation is unlikely to occur and which has excellent low-temperature bag-making properties.　The laminated sealant film satisfies all of the following 1) to 7). 1) At least a laminate layer, an intermediate layer, and a seal layer are included in the stated order. 2) The laminate layer and the intermediate layer are each formed of a polypropylene-based resin composition, and the seal layer is formed of a resin composition containing a 1-butene copolymer. 3) The ratio of the melt flow rate of the polypropylene-based resin composition in the intermediate layer with respect to the melt flow rate of the polypropylene-based resin composition in the laminate layer is 0.6-2.0. 4) The ratio of the melt flow rate of the resin composition containing the 1-butene copolymer in the seal layer with respect to the melt flow rate of the polypropylene-based resin composition in the intermediate layer is 0.6-3.5. 5) The melt flow rates of the polypropylene-based resin composition in the laminate layer, the polypropylene-based resin composition in the intermediate layer, and the resin composition containing the 1-butene copolymer in the seal layer are each 1-9 g / 10 min (load 2.16 kgf). 6) The melting point of the resin composition containing the 1-butene copolymer in the seal layer is 50-140°C. 7) The tensile elastic modulus in the longitudinal direction is 600 MPa or less.

Description

Laminated Sealant Film

[0001] The present invention relates to a polypropylene-based laminated sealant film that is resistant to delamination and has excellent low-temperature bag-forming properties.

[0002] As disclosed in Patent Documents 1 to 5, packaging materials have been developed to suit the contents of many products, such as foods, beverages, pharmaceuticals, and chemicals. Packaging materials are used in various forms, such as pillow packaging, gusset packaging, and three-sided seal packaging, and the sealant films used in packaging materials also have functions required for their applications.

[0003] Japanese Patent No. 4731699 Japanese Patent Application Laid-Open No. 2000-272064 Japanese Patent Application Laid-Open No. 2000-272065 Japanese Patent Application Laid-Open No. 2002-241716 Japanese Patent Application Laid-Open No. 2020-192695

[0004] Sealant films are particularly suitable for automatic bag-making processes for pillowcase packaging bags, gusset packaging bags, and three-sided sealed packaging bags while packaging the contents. The lower the heat-sealing temperature, the lower the electricity bill and the lower the risk of burns, improving workability. Furthermore, low-temperature heat-sealing properties increase packaging and bag-making speeds, reduce packaging material waste, and produce cleaner finished packaging bags. However, to date, there has been no polypropylene-based laminated sealant film that is resistant to delamination and has excellent low-temperature bag-making properties. Therefore, an object of the present invention is to provide a polypropylene-based laminated sealant film that is resistant to delamination and has excellent low-temperature bag-making properties.

[0005] As a result of extensive research to achieve this object, the inventors have succeeded in obtaining a polypropylene-based laminate sealant film that is less susceptible to delamination and has excellent bag-forming properties at low temperatures by controlling the raw material composition of each layer of the laminate sealant film and the elastic modulus of the entire film. The laminate sealant film according to the embodiment is as follows [1], and preferably any one of [2] to

[12] .

[0006] [1] A laminated sealant film that satisfies all of the following 1) to 7): 1) It comprises at least a laminate layer, an intermediate layer, and a seal layer, in this order. 2) The laminate layer and the intermediate layer are each made of a polypropylene-based resin composition, and the seal layer is made of a resin composition containing a 1-butene copolymer. 3) The ratio of the melt flow rate of the polypropylene-based resin composition of the intermediate layer to the melt flow rate of the polypropylene-based resin composition of the laminate layer is 0.6 or more and 2.0 or less. 4) The ratio of the melt flow rate of the resin composition containing a 1-butene copolymer of the seal layer to the melt flow rate of the polypropylene-based resin composition of the intermediate layer is 0.6 or more and 3.5 or less. 5) The polypropylene resin composition of the laminate layer, the polypropylene resin composition of the intermediate layer, and the resin composition containing the 1-butene copolymer of the seal layer have melt flow rates of 1 g / 10 min (load 2.16 kgf) or more and 9 g / 10 min (load 2.16 kgf) or less, respectively. 6) The resin composition containing the 1-butene copolymer of the seal layer has a melting point of 50°C or more and 140°C or less. 7) The tensile modulus in the longitudinal direction is 600 MPa or less. [2] The polypropylene resin composition of the laminate layer and the polypropylene resin composition of the intermediate layer contain a polypropylene resin, and the polypropylene resin is a propylene random copolymer. [3] The laminate sealant film of [1] or [2], wherein the film has a main peak of melting point of 120°C or more and 160°C or less. [4] The laminate sealant film according to any one of [1] to [3], wherein the coefficient of static friction between the surfaces of the sealing layer is 1.0 or less. [5] The laminate sealant film according to any one of [1] to [4], wherein the coefficient of dynamic friction between the surfaces of the sealing layer is 1.0 or less. [6] The laminate sealant film according to any one of [1] to [5], wherein the sealing layer comprises silica. [7] The laminate sealant film according to any one of [1] to [6], wherein the sealing layer comprises erucic acid amide. [8] The laminate sealant film according to any one of [1] to [7], wherein the sealing layer comprises organic particles.[9] The laminate sealant film according to any one of [1] to [8], wherein the tensile modulus in the longitudinal direction is 200 MPa or more and 600 MPa or less.

[10] The laminate sealant film according to any one of [1] to [9], wherein the resin composition containing the 1-butene copolymer in the seal layer contains a polypropylene-based resin, and the polypropylene-based resin is a propylene random copolymer.

[11] The laminate sealant film according to [1], wherein the 1-butene copolymer in the seal layer is a random copolymer of 1-butene and propylene.

[12] The laminate sealant film according to any one of [2] to

[11] , wherein the propylene random copolymer is a random copolymer of propylene, ethylene, and butene-1.

[0007] According to the present invention, a polypropylene-based laminated sealant film that is resistant to delamination and has excellent low-temperature bag-forming properties can be provided. Because of its excellent low-temperature bag-forming properties, the laminated sealant film is suitable as a packaging material for many products, such as food, beverages, pharmaceuticals, and chemicals. It is particularly suitable for automatic bag-forming into pillow packaging bags, gusset packaging bags, three-side seal packaging bags, and the like while packaging the contents.

[0008] The laminate sealant film according to the embodiment satisfies all of the following 1) to 7). 1) It comprises at least a laminate layer, an intermediate layer, and a seal layer, in this order. 2) The laminate layer and the intermediate layer are each made of a polypropylene-based resin composition, and the seal layer is made of a resin composition containing a 1-butene copolymer. 3) The ratio of the melt flow rate of the polypropylene-based resin composition of the intermediate layer to the melt flow rate of the polypropylene-based resin composition of the laminate layer is 0.6 or more and 2.0 or less. 4) The ratio of the melt flow rate of the resin composition containing a 1-butene copolymer of the seal layer to the melt flow rate of the polypropylene-based resin composition of the intermediate layer is 0.6 or more and 3.5 or less. 5) The polypropylene resin composition of the laminate layer, the polypropylene resin composition of the intermediate layer, and the resin composition containing a 1-butene copolymer of the seal layer have melt flow rates of 1 g / 10 min (load 2.16 kgf) or more and 9 g / 10 min (load 2.16 kgf) or less, respectively. 6) The resin composition containing a 1-butene copolymer of the seal layer has a melting point of 50°C or more and 140°C or less. 7) The tensile modulus in the longitudinal direction is 600 MPa or less.

[0009] The laminate sealant film according to the embodiment will be described below. The laminate sealant film according to the embodiment includes at least a laminate layer, an intermediate layer, and a seal layer in this order. The laminate layer, the intermediate layer, and the seal layer will be described in detail below.

[0010] (Laminate Layer) The laminate layer is made of a polypropylene-based resin composition containing a polypropylene-based resin as a main component. The term "main component" means that the polypropylene-based resin accounts for 90% by mass or more of the polypropylene-based resin composition, preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more. This proportion is preferably 100% by mass or less. The laminate layer preferably contains 95% by mass or more of the polypropylene-based resin composition, more preferably 97% by mass or more, even more preferably 99% by mass or more, and particularly preferably 100% by mass. The laminate layer may contain unavoidable impurities in addition to the polypropylene-based resin composition.

[0011] (Polypropylene-Based Resin) The polypropylene-based resin in the laminate layer is a resin containing propylene as a main component, and examples thereof include propylene homopolymers, random copolymers and block copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc. Among these, random copolymers and / or block copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1 are preferred, propylene random copolymers, which are random copolymers of propylene and one or more α-olefins, are more preferred, and random copolymers of propylene, ethylene, and butene-1 are even more preferred. The term "main component" means that the proportion of propylene in the polypropylene-based resin is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more. The proportion is preferably 100% by mass or less.

[0012] The polypropylene resin composition of the laminate layer preferably has a melt flow rate (load 2.16 kgf) of 1 g / 10 min or more and 9 g / 10 min or less, more preferably 1.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 2 g / 10 min or more and 7 g / 10 min or less. The melt flow rate can be measured in accordance with JIS K7210.

[0013] The upper limit of the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower. When the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is 160°C or lower, the tensile modulus of the laminate sealant film is easily set to 600 MPa or lower, and the bag breakage strength is also improved. The lower limit of the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher. When the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is 120°C or higher, the laminate sealant film is less likely to wrinkle when subjected to, for example, retort treatment, and transparency is easily maintained. Furthermore, when laminated with a stretched polypropylene film, it is possible to obtain packaging bags made of the same material, and the film can be used for applications that could not be handled with sealant films made of polyethylene resins. It is useful as a so-called mono-material film.

[0014] In addition to the polypropylene-based resin, the polypropylene-based resin composition of the laminate layer may contain, for example, at least one ethylene homopolymer selected from the group consisting of high-pressure low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. Furthermore, it may contain a random or block copolymer, or a mixture thereof, primarily composed of ethylene and copolymerized with other monomers, such as α-olefins such as propylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1, vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters. These may be crystalline, low-crystalline, or amorphous. The content of these polymers other than the polypropylene-based resin in the laminate layer is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less. This proportion may be 0.1% by mass or more.

[0015] The polyethylene resin of the laminate layer preferably has a melt flow rate (load 2.16 kgf) of 0.1 g / 10 min or more and 9 g / 10 min or less, more preferably 0.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 1 g / 10 min or more and 7 g / 10 min or less. The melt flow rate can be measured in accordance with JIS K7210. The polyethylene resin of the laminate layer preferably has a melting point (JIS K7121) of 100°C or more and 140°C or less, more preferably 105°C or more and 135°C or less, and even more preferably 110°C or more and 130°C or less. The melting point of the polyethylene resin may show two or more melting endothermic peaks, and the peak with the highest melting temperature is considered to be the main peak.

[0016] (Antiblocking Agent) The polypropylene resin composition of the laminate layer preferably contains an antiblocking agent. Examples of antiblocking agents include silica particles such as synthetic silica, inorganic particles such as diatomaceous earth, zeolite, talc, and mica, and organic particles such as silicone particles, acrylic particles, nylon particles, and polyethylene particles. It is more preferable to contain zeolite and / or polyethylene particles. In particular, it is preferable to contain zeolite and polyethylene particles. The average particle size of the particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 4 μm or more. The average particle size of the particles is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The particle size is the volume average particle size.

[0017] The particle content in the polypropylene resin composition of the laminate layer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more. It is also preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less. When the particle content is 2% by mass or less, the surface protrusions are not too numerous, and poor appearance and reduced abrasion resistance are less likely to occur.

[0018] (Organic Lubricant) The polypropylene resin composition of the laminate layer preferably contains 0.01% by mass or more and 2.0% by mass or less of a fatty acid amide as an organic lubricant, more preferably 0.05% by mass or more and 1.5% by mass or less, and particularly preferably 0.1% by mass or more and 1.0% by mass or less. When the fatty acid amide is 0.01% by mass or more, blocking between films is not too strong, and the film handling is likely to be satisfactory. When the fatty acid amide is 2.0% by mass or less, the seal strength is unlikely to decrease. Examples of fatty acid amides include erucic acid amide, ethylene bisoleic acid amide, and behenic acid amide, and these may be used in combination.

[0019] The closer the melt flow rate of the resin composition or raw material resin of the laminate layer is to that of the resin composition or raw material resin of the intermediate layer, the better the appearance. Therefore, the ratio of the melt flow rate of the polypropylene resin composition of the intermediate layer to the melt flow rate of the polypropylene resin composition of the laminate layer is 0.6 to 2.0, preferably 0.7 to 1.6, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.2. When the melt flow rate ratio is within this range, poor appearance such as layer misalignment, blemishes, and unevenness is less likely to occur.

[0020] (Intermediate layer) The intermediate layer is made of a polypropylene-based resin composition containing a polypropylene-based resin as a main component. The term "main component" means that the polypropylene-based resin accounts for 80% by mass or more of the polypropylene-based resin composition, preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. This proportion is preferably 100% by mass or less. The intermediate layer preferably contains 95% by mass or more of the polypropylene-based resin composition, more preferably 97% by mass or more, even more preferably 99% by mass or more, and particularly preferably 100% by mass. The intermediate layer may contain unavoidable impurities in addition to the polypropylene-based resin composition.

[0021] (Polypropylene Resin) The polypropylene resin in the intermediate layer is a resin containing propylene as a main component, and examples thereof include propylene homopolymers, random copolymers and block copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc. Among these, random copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1 are preferred, propylene random copolymers which are random copolymers of propylene and one or more α-olefins are more preferred, and random copolymers of propylene, ethylene, and butene-1 are even more preferred. The term "main component" means that the proportion of propylene in the polypropylene-based resin is 90% by mass or more, preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more. The proportion is preferably 100% by mass or less.

[0022] The polypropylene resin composition of the intermediate layer preferably has a melt flow rate (load 2.16 kgf) of 1 g / 10 min or more and 9 g / 10 min or less, more preferably 1.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 2 g / 10 min or more and 7 g / 10 min or less. The melt flow rate can be measured in accordance with JIS K7210. The upper limit of the melting point (JIS K7121) of the polypropylene resin composition of the intermediate layer is preferably 150°C or less, more preferably 145°C or less, and even more preferably 140°C or less. When the melting point (JIS K7121) of the polypropylene resin of the intermediate layer is 150°C or less, the tensile modulus of the laminate sealant film is easily set to 600 MPa or less, and the bag breakage strength is also improved. The lower limit of the melting point (JIS K7121) of the polypropylene resin composition of the intermediate layer is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher. When the melting point (JIS K7121) of the polypropylene resin composition of the intermediate layer is 120°C or higher, the laminated sealant film is less likely to wrinkle when subjected to, for example, retort treatment, and transparency is easily maintained. Furthermore, the laminated sealant film can be used for applications that could not be achieved with sealant films made of polyethylene resins, such as laminating it with an OPP film to form a mono-material film.

[0023] In addition to the polypropylene resin, the polypropylene resin composition of the intermediate layer may contain, for example, at least one 1-butene copolymer selected from the group consisting of ethylene-1-butene copolymer, 1-butene-ethylene copolymer, propylene-1-butene copolymer, and 1-butene-propylene copolymer. These copolymers may be random or block copolymers, or mixtures thereof. They may be crystalline, low-crystalline, or amorphous. The content of these polymers other than polypropylene resins in the intermediate layer is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less. This proportion may be 0.1% by mass or more.

[0024] The ethylene-1-butene copolymer, 1-butene-ethylene copolymer, propylene-1-butene copolymer, and 1-butene-propylene copolymer of the intermediate layer preferably have a melt flow rate of 0.1 g / 10 min or more and 9 g / 10 min or less, more preferably 0.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 1 g / 10 min or more and 7 g / 10 min or less. The ethylene-1-butene copolymer, 1-butene-ethylene copolymer, propylene-1-butene copolymer, and 1-butene-propylene copolymer of the intermediate layer preferably have a melting point of 50°C or more and 140°C or less, more preferably 60°C or more and 135°C or less, even more preferably 70°C or more and 130°C or less, and particularly preferably 80°C or more and 120°C or less. The melting points of the ethylene / 1-butene copolymer, 1-butene / ethylene copolymer, propylene / 1-butene copolymer, and 1-butene / propylene copolymer may show two or more melting endothermic peaks, and the peak with the highest melting temperature is defined as the main peak.

[0025] (Anti-blocking agent) The polypropylene resin composition of the intermediate layer may contain an anti-blocking agent. Examples of anti-blocking agents include silica particles such as synthetic silica, inorganic particles such as diatomaceous earth, zeolite, talc, and mica, and organic particles such as silicone particles, acrylic particles, nylon particles, and polyethylene particles. It is more preferable to contain zeolite and / or polyethylene particles. It is particularly preferable to contain zeolite and polyethylene particles. The average particle size of the particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 5 μm or more. The average particle size of the particles is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The particle size is the volume average particle size.

[0026] The particle content in the polypropylene resin composition of the intermediate layer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less.

[0027] (Organic Lubricant) The polypropylene resin composition of the intermediate layer may contain a fatty acid amide, preferably from 0.01% by mass to 2.0% by mass, more preferably from 0.05% by mass to 1.5% by mass, and particularly preferably from 0.1% by mass to 1.0% by mass. Examples of the fatty acid amide include erucic acid amide, ethylene bisoleic acid amide, and behenic acid amide, and these may be used in combination.

[0028] The closer the melt flow rate of the resin composition or raw material resin of the intermediate layer is to the melt flow rate of the resin composition or raw material resin of the seal layer, the better the appearance. Therefore, the ratio of the melt flow rate of the resin composition containing 1-butene copolymer of the seal layer to the melt flow rate of the polypropylene resin composition of the intermediate layer is 0.6 to 3.5, preferably 0.7 to 1.8, more preferably 0.8 to 1.6, even more preferably 0.9 to 1.4, and particularly preferably 0.9 to 1.2. When the melt flow rate ratio is within this range, poor appearance such as layer misalignment, blemishes, and unevenness is less likely to occur.

[0029] (Sealing Layer) The sealing layer is made of a resin composition containing a 1-butene copolymer. The content of the 1-butene copolymer relative to the resin composition containing the 1-butene copolymer in the sealing layer is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 18% by mass or more. When the content of the 1-butene copolymer is 10% by mass or more, the hermetic seal initiation temperature can be lowered. To lower the flat seal initiation temperature, the content of the 1-butene copolymer is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more. Furthermore, the content of the 1-butene copolymer relative to the resin composition of the sealing layer is preferably 100% by mass or less, more preferably 80% by mass or less, even more preferably 60% by mass or less, and even more preferably 40% by mass or less. When the content of the 1-butene copolymer is 60% by mass or less, it can be suitably used in boiling applications. The sealing layer preferably contains 95% by mass or more of a resin composition containing a 1-butene copolymer, more preferably 97% by mass or more, even more preferably 99% by mass or more, and particularly preferably 100% by mass. The sealing layer may contain inevitable impurities in addition to the resin composition containing a 1-butene copolymer.

[0030] (1-Butene Copolymer) The 1-butene copolymer in the seal layer is a resin containing 1-butene, and examples thereof include 1-butene homopolymers, random copolymers and block copolymers of 1-butene with one or more α-olefins such as ethylene, propylene, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1. Of these, random copolymers of 1-butene with one or more α-olefins such as ethylene, propylene, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1 are preferred, and random copolymers of 1-butene and propylene are preferred. These copolymers may contain 1-butene, and the content of 1-butene-derived components in the 1-butene copolymer is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, particularly preferably 30% by mass or more, and most preferably 60% by mass or more. On the other hand, the content is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. 1-Butene copolymers have superior low-temperature sealing properties compared to polypropylene-based resins and polyethylene-based resins.

[0031] The resin composition containing the 1-butene copolymer of the sealing layer preferably has a melt flow rate (load 2.16 kgf) of 1 g / 10 min or more and 9 g / 10 min or less, more preferably 1.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 2 g / 10 min or more and 7 g / 10 min or less. The melt flow rate can be measured in accordance with JIS K7112. The resin composition containing the 1-butene copolymer of the sealing layer has a melting point of 140°C or less, preferably 120°C or less, more preferably 110°C or less, even more preferably 100°C or less, and particularly preferably 90°C or less. When the melting point of the resin composition containing the 1-butene copolymer of the sealing layer is 140°C or less, the low-temperature sealability (effect) is excellent. The resin composition containing a 1-butene copolymer in the seal layer has a melting point of 50° C. or higher, preferably 55° C. or higher, more preferably 60° C. or higher, even more preferably 70° C. or higher, particularly preferably 80° C. or higher, and most preferably 100° C. or higher. When used in boiling applications or when hot tackiness is not required, the resin composition containing a 1-butene copolymer preferably has a melting point of 100° C. or higher.

[0032] (Polypropylene-based Resin) The resin composition containing a 1-butene copolymer of the seal layer preferably contains a polypropylene-based resin in addition to the 1-butene copolymer. The polypropylene-based resin is a resin whose main component is propylene, and examples thereof include propylene homopolymers, random copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1, and block copolymers. Among these, random copolymers of propylene and one or more α-olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1 are preferred, and propylene random copolymers, which are random copolymers of propylene and one or more α-olefins, are more preferred, and random copolymers of propylene, ethylene, and butene-1 are even more preferred. The term "main component" means that propylene accounts for 90% by mass or more of the polypropylene-based resin, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 99% by mass or more. This proportion is preferably 100% by mass or less. Polypropylene-based resins have a higher melting point and superior transparency than polyethylene-based resins. The content of the polypropylene-based resin in the resin composition containing the 1-butene copolymer in the seal layer is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 82% by mass or less, even more preferably 70% by mass or less, particularly preferably 50% by mass or less, and most preferably 30% by mass or less.

[0033] The polypropylene resin of the sealing layer preferably has a melt flow rate (load 2.16 kgf) of 1 g / 10 min or more and 9 g / 10 min or less, more preferably 1.5 g / 10 min or more and 8 g / 10 min or less, and even more preferably 2 g / 10 min or more and 7 g / 10 min or less. The melt flow rate can be measured in accordance with JIS K7210. The polypropylene resin of the sealing layer preferably has a melting point of 140 ° C or less, more preferably 135 ° C or less. When the melting point of the polypropylene resin of the sealing layer is 140 ° C or less, it has excellent low-temperature sealing properties (effectiveness). The polypropylene resin of the sealing layer preferably has a melting point of 100 ° C or more, more preferably 110 ° C or more, even more preferably 120 ° C or more, and particularly preferably 125 ° C or more. When the melting point of the polypropylene resin of the sealing layer is 100 ° C or more, it has excellent heat resistance such as boiling resistance and self-supporting properties.

[0034] (Anti-blocking Agent) The resin composition of the sealing layer containing a 1-butene copolymer preferably contains an anti-blocking agent. Examples of anti-blocking agents include particles made of silica such as synthetic silica, inorganic particles such as diatomaceous earth, zeolite, talc, and mica, and organic particles such as silicone particles, acrylic particles, nylon particles, and polyethylene particles. It is more preferable to contain zeolite and / or polyethylene particles. In particular, it is preferable to contain zeolite and polyethylene particles. The average particle size of the particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 4 μm or more. The average particle size of the particles is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The particle size is the volume average particle size.

[0035] The particle content in the resin composition containing the 1-butene copolymer of the sealing layer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.4% by mass or more. It is also preferably 2% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1.0% by mass or less. If the particle content is less than 0.1% by mass, it becomes difficult to achieve a surface roughness Ra of 0.1 μm or more for at least one surface layer, making it difficult to obtain anti-blocking properties and slip properties. Furthermore, by adding particles in an amount of 2% by mass or less, surface protrusions can be reduced, making it easier to prevent the occurrence of abrasion resistance.

[0036] (Organic Lubricant) The resin composition containing 1-butene copolymer of the sealing layer preferably contains 0.01% by mass or more and 2.0% by mass or less of a fatty acid amide as an organic lubricant, more preferably 0.05% by mass or more and 1.5% by mass or less, and particularly preferably 0.1% by mass or more and 1.0% by mass or less. When the fatty acid amide content is 0.01% by mass or more, blocking between films is reduced, making it easier to handle the film. When the content is 2.0% by mass or less, the seal strength is less likely to decrease. Examples of fatty acid amides include erucic acid amide, ethylene bisoleic acid amide, and behenic acid amide, and these may be used in combination. In particular, erucic acid amide has a low melting point, is easy to bleed, and is easy to impart lubricity. It is more preferable that the sealing layer contain both zeolite as an antiblocking agent and erucic acid amide as an organic lubricant. It is more preferable that the sealing layer contain both polyethylene particles as an antiblocking agent and erucic acid amide as an organic lubricant. More preferably, the sealing layer contains zeolite and polyethylene particles as an antiblocking agent in combination with erucamide as an organic lubricant.

[0037] (Layer Structure) Examples of the layer structure of the laminate sealant film include laminate layer / intermediate layer / sealing layer and laminate layer / intermediate layer 1 / intermediate layer 2 / sealing layer. For example, laminate layer / intermediate layer / sealing layer indicates a structure in which a laminate layer, an intermediate layer, and a sealing layer are laminated in this order. Arranging an intermediate layer between the laminate layer and the sealing layer is preferable because it reduces peeling between the laminate layer and the sealing layer and makes it easier to use recycled raw materials. The raw material composition of the intermediate layer is preferably intermediate between the laminate layer and the sealing layer to reduce peeling between the laminate layer and the sealing layer. The thickness of the laminate layer is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the sealing layer is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the intermediate layer is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. The thickness of the laminate layer is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. The thickness of the seal layer is preferably 12 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. The thickness of the intermediate layer is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. The ratio of the thickness of the intermediate layer to the thickness of the laminate layer is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. The ratio of the thickness of the seal layer to the thickness of the laminate layer is preferably 0.3 or more and 1.5 or less, and preferably 0.5 or more and 1.2 or less. The ratio of the thickness of the intermediate layer to the thickness of the seal layer is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more.

[0038] The smaller the difference in melt flow rate between the raw material resins of adjacent layers and / or the smaller the difference in melt flow rate between the raw material resins mixed in each layer, the better the appearance. The ratio of the melt flow rates of the raw material resins of adjacent layers is preferably 0.6 or more and 2.0 or less. When the melt flow rate ratio is within this range, poor appearance such as layer misalignment, blemishes, and unevenness is less likely to occur. Furthermore, the melting point of the laminated sealant film is preferably 120°C or more, more preferably 130°C or more, and even more preferably 140°C or more. When the main peak of the film's melting point is 120°C or more, the boil resistance and retort resistance are further improved. The main peak of the melting point of the laminated sealant film is preferably 160°C or less, more preferably 150°C or less.

[0039] (Method for producing laminate sealant film) The method for producing a laminate sealant film will be described in detail below, but is not limited thereto. First, the resin compositions of the laminate layer, intermediate layer, and seal layer are blended with the above-mentioned resin raw materials and, if necessary, various additives using a mixer such as a Henschel mixer, a Banbury mixer, or a tumbler mixer to produce the film. Then, the obtained resin composition can be used to form a multilayer film.

[0040] (Melt Extrusion Process) The mixed resin composition is melted, for example, under conditions of a resin temperature of 110°C or higher and 300°C or lower, and melt-extruded into a sheet form, for example, through a T-die, cast onto a cooling roll, and cooled and solidified to obtain an unstretched sheet. A specific method for this is preferably casting onto a cooling roll. Multilayering can be achieved using a multilayering device such as a multilayer feed block, a static mixer, or a multi-manifold die. For example, resins delivered from different flow paths using two or more extruders can be laminated into multiple layers using a multilayer feed block or a multi-manifold die. Examples of methods include melt-extruding a melt-kneaded laminated resin composition sheet and forming it into a film using a T-die method or an inflation method. However, the T-die method is particularly preferred because it allows for a high resin melt temperature.

[0041] (Cooling and Solidification Process) For example, it is preferable to cast a sheet melt-extruded from a T-die onto a chill roll and cool it. The lower limit of the chill roll temperature is preferably 10°C. If the temperature is lower than this, not only may the crystallization suppression effect saturate, but problems such as condensation may also occur, which is undesirable. The upper limit of the chill roll temperature is preferably 70°C or lower. If the temperature exceeds this range, crystallization will progress and transparency will deteriorate, which is undesirable. Furthermore, when the chill roll temperature is within the above range, it is preferable to reduce the humidity of the environment near the chill roll to prevent condensation. During casting, the surface temperature of the chill roll rises because the hot resin comes into contact with the surface. Typically, chill rolls are cooled by flowing cooling water through piping inside. However, it is necessary to reduce the temperature difference across the width of the chill roll surface by ensuring a sufficient amount of cooling water, optimizing the piping arrangement, and performing maintenance to prevent sludge from adhering to the piping. In this case, the thickness of the unstretched sheet is preferably in the range of 3 μm to 200 μm. The thickness of the film is preferably in the range of 5 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less.

[0042] The unstretched sheet obtained may be stretched, but stretching to a ratio of 2.0 or more will result in a tensile modulus of elasticity exceeding 600 MPa, so the stretching ratio is preferably less than 2.0.

[0043] (Film characteristics) The film characteristics will be described. The "longitudinal direction" of the laminate sealant film is the direction corresponding to the flow direction in the film manufacturing process, and the "width direction" is the direction perpendicular to the flow direction in the film manufacturing process. Hereinafter, the "longitudinal direction" may be abbreviated as the "MD direction" and the "width direction" may be abbreviated as the "TD direction."

[0044] (Tensile modulus) The upper limit of the longitudinal tensile modulus of the laminate sealant film is preferably 600 MPa or less, more preferably 580 MPa or less, even more preferably 560 MPa or less, even more preferably 540 MPa or less, particularly preferably 520 MPa or less, and most preferably 500 MPa or less. When the longitudinal tensile modulus is 600 MPa or less, the low-temperature sealing effect at the sealing initiation temperature is improved. The lower limit of the longitudinal tensile modulus of the laminate sealant film is preferably 200 MPa or more, more preferably 250 MPa or more, even more preferably 300 MPa or more, and even more preferably 325 MPa or more. When the longitudinal tensile modulus is 200 MPa or more, bag-making processing is easier. The upper limit of the widthwise tensile modulus of the laminate sealant film is preferably 580 MPa or less, more preferably 530 MPa or less, even more preferably 500 MPa or less, even more preferably 480 MPa or less, and particularly preferably 440 MPa or less. When the tensile modulus in the width direction is 580 MPa or less, the low-temperature sealing effect of the sealing initiation temperature is improved. The lower limit of the tensile modulus in the width direction of the laminated sealant film is preferably 200 MPa or more, more preferably 250 MPa or more, even more preferably 300 MPa or more, and even more preferably 325 MPa or more. When the tensile modulus in the width direction is 200 MPa or more, bag-making processing is easier.

[0045] The upper limit of the sum of the longitudinal tensile modulus and the widthwise tensile modulus of the laminated sealant film is preferably 1180 MPa or less, more preferably 1130 MPa or less, even more preferably 1080 MPa or less, even more preferably 1030 MPa or less, particularly preferably 980 MPa or less, and most preferably 930 MPa or less. When the longitudinal tensile modulus is 1180 MPa or less, the low-temperature sealing effect of the sealing start temperature is improved. The lower limit of the sum of the longitudinal tensile modulus and the widthwise tensile modulus of the laminated sealant film is preferably 400 MPa or more, more preferably 500 MPa or more, even more preferably 600 MPa or more, and even more preferably 650 MPa or more. When the longitudinal tensile modulus is 400 MPa or more, bag-making processing is easier. The upper limit of the average of the longitudinal and width tensile moduli of the laminated sealant film is preferably 600 MPa or less, more preferably 580 MPa or less, even more preferably 560 MPa or less, even more preferably 540 MPa or less, and particularly preferably 520 MPa or less. When the average of the longitudinal and width tensile moduli is 600 MPa or less, the low-temperature sealing effect of the sealing start temperature is improved. The lower limit of the average of the longitudinal and width tensile moduli of the laminated sealant film is preferably 200 MPa or more, more preferably 250 MPa or more, even more preferably 300 MPa or more, and even more preferably 325 MPa or more. When the longitudinal tensile modulus is 200 MPa or more, bag-making processing is easier.

[0046] (Haze) The haze of the laminated sealant film is preferably 10% or less, more preferably 9% or less, even more preferably 8% or less, even more preferably 7% or less, and particularly preferably 5% or less. If the haze exceeds 10%, the film often has streaks or scratches, and the contents become difficult to see. The haze of the laminated sealant film is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more. If the haze is 1% or more, the coefficient of friction is less likely to increase.

[0047] (Appearance Unevenness) The closer the melt flow rates of the resin composition or raw resin of the seal layer and the resin composition or raw resin of the intermediate layer, the better the appearance of the laminated sealant film. The more the melt flow rates differ, the more likely appearance unevenness occurs.

[0048] (Delamination) The delamination of a laminated sealant film refers to the case where, for example, delamination occurs between the seal layer and the intermediate layer when measuring the flat seal initiation temperature, the hermetic seal initiation temperature, or the burst strength. If delamination occurs, it becomes difficult to remove the contents, so it is preferable that delamination does not occur. Delamination is likely to occur when the components or component ratios of the resin compositions of the seal layer and the intermediate layer and / or the intermediate layer and the laminate layer are significantly different.

[0049] (Flat seal initiation temperature) The flat seal initiation temperature of the laminated sealant film is preferably 50°C or higher and 150°C or lower, more preferably 70°C or higher and 140°C or lower, even more preferably 100°C or higher and 130°C or lower, and even more preferably 105°C or higher and 121°C or lower. The flat seal initiation temperature preferably has a lower limit of 30°C or higher than the melting point of the polypropylene-based resin of the seal layer and an upper limit of 10°C or higher than the melting point of the polypropylene-based resin of the laminate layer. The low-temperature sealing effect of the flat seal initiation temperature is evaluated based on the degree of reduction in heat sealing temperature, using the heat sealing temperature in Comparative Example 3 described below as a reference. The low-temperature sealing effect of the flat seal initiation temperature is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, even more preferably 60°C or higher, and particularly preferably 70°C or higher.

[0050] (Sealing start temperature) The sealing start temperature of the laminated sealant film is preferably 100°C or higher and lower than 140°C, more preferably 110°C or higher and 135°C or lower, and even more preferably 120°C or higher and 130°C or lower. The sealing start temperature preferably has a lower limit that is 30°C or higher than the lowest melting point of the polypropylene-based resin in the seal layer and an upper limit that is 10°C or higher than the highest melting point of the polypropylene-based resin in the laminate layer. The low-temperature sealing effect of the sealing start temperature is evaluated based on the degree of decrease in the sealing temperature, using the sealing temperature in Comparative Example 3 described below as a reference. The low-temperature sealability of the sealing start temperature is preferably above 10°C, more preferably 15°C or higher, even more preferably 20°C or higher, particularly preferably 25°C or higher, and most preferably 30°C or higher.

[0051] (Hot tack property) The hot tack property of the laminated sealant film is preferably such that the tack peel distance is 20 mm or less at a lower temperature. Here, good hot tack property means that the seal strength between sealant films is sufficient even when the resin of the sealant film is in a molten state. The low-temperature sealing effect of hot tack property is evaluated based on the degree of reduction in heat sealing temperature, using the hot tack temperature in Comparative Example 3 described below as the standard. The low-temperature sealing effect of hot tack property is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, even more preferably 60°C or higher, and particularly preferably 70°C or higher.

[0052] The seal layer contains a 1-butene copolymer, which has a lower melting point, thereby lowering the flat seal initiation temperature and the hermetic seal initiation temperature, thereby achieving low-temperature sealability. Furthermore, the laminate layer, intermediate layer, and seal layer contain a polypropylene-based resin, which facilitates maintaining the heat resistance of the laminate sealant film and reduces delamination.

[0053] (Impact Strength) It is preferable that the impact strength of the laminate sealant film is less likely to decrease even at a low temperature of 5° C. or less than the impact strength at room temperature. In particular, the higher the mixing ratio of the 1-butene copolymer in the seal layer, the less likely the impact strength at low temperatures to decrease.

[0054] (Improvement in cold resistance) The improvement in cold resistance of the impact strength of the laminate sealant film is evaluated by the difference from the impact strength at 0° C., using the impact strength at 0° C. in Comparative Example 3 described below as the standard. The improvement in cold resistance of the impact strength is preferably 0.05 J or more, more preferably 0.10 J or more, even more preferably 0.15 J or more, even more preferably 0.20 J or more, and particularly preferably 0.25 J or more.

[0055] (Burst Strength) The burst strength of a laminate sealant film is evaluated using a bag made from the laminate sealant film. When a high burst strength is required, such as for retort sterilization, it is preferably 20 kPa or more, more preferably 25 kPa or more. On the other hand, the burst strength of a laminate sealant film may be 35 kPa or less, or even 30 kPa or less. By optimizing the melting point of the sealing layer and the elastic modulus of the film, it has been confirmed that the laminate sealant film not only achieves a low-temperature sealing effect at least at the flat seal initiation temperature and the hermetic seal initiation temperature, but also improves its burst strength. This is thought to be due to the fact that the bag becomes more easily deformed by optimizing the elastic modulus in particular, thereby improving the burst strength.

[0056] (Static Friction Coefficient and Dynamic Friction Coefficient) The static friction coefficient and dynamic friction coefficient of the laminated sealant film between the surfaces of the seal layers at a load of 0.5 kgf are preferably 2.0 or less, more preferably 1.0 or less, and even more preferably 0.5 or less. When the static friction coefficient and / or dynamic friction coefficient is 2.0 or less, the sliding property between the films is sufficient, and the handling property as a packaging material is improved.

[0057] This application claims the benefit of priority based on Japanese Patent Application No. 2023-080159, filed on May 15, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-080159, filed on May 15, 2023, are incorporated herein by reference.

[0058] (Melting Point of Resin) The melting point of the resin was measured in accordance with JIS K7121 using a differential scanning calorimeter (Seiko Instruments Inc., DSC60). Specifically, about 5 mg of a sample was packed into an aluminum pan, heated from room temperature to 200°C at a heating / cooling rate of 10°C / min, held at 200°C for 3 minutes, cooled to 23°C, held at 23°C for 3 minutes, and then heated again to 200°C. The temperature of the highest melting endothermic peak was taken as the melting point. When there were two or more melting endothermic peaks, the highest melting endothermic peak was taken as the melting point.

[0059] (Melting Point of Laminated Sealant Film) The melting point of the laminated sealant film was measured in accordance with JIS K7121 using a differential scanning calorimeter (Seiko Instruments Inc., DSC60). Specifically, about 5 mg of the laminated sealant film was packed into an aluminum pan, heated from room temperature to 200°C at a heating / cooling rate of 10°C / min, held at 200°C for 3 minutes, cooled to 23°C, held at 23°C for 3 minutes, and then heated again to 200°C. The temperature of the highest melting endothermic peak was taken as the melting point. When there were two or more melting endothermic peaks, the highest melting endothermic peak was taken as the melting point.

[0060] (Melt Flow Rate) In accordance with JIS K7210, measurements were taken using a thermal flow evaluation device (Shimadzu Corporation, capillary rheometer, CFT-500D) under a load of 2.16 kgf at a temperature of 230°C for polypropylene-based resins and 1-butene copolymers, and at a temperature of 190°C for polyethylene-based resins such as L-LDPE.

[0061] (Average particle size of particles) Inorganic particles or polyethylene particles were dispersed in ion-exchanged water stirred at a predetermined rotation speed (about 5000 rpm) using a high-speed stirrer, and the resulting dispersion was added to Isotone (physiological saline) and further dispersed using an ultrasonic disperser. The particle size distribution was then determined by the Coulter counter method, and the volume average particle size was calculated. The refractive index used was 1.30 for physiological saline, 1.457 for silicates such as synthetic silica and zeolite, and 1.54 for polyethylene.

[0062] (Flat seal initiation temperature) A laminated sealant film and a biaxially oriented polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Toyobo Ester (registered trademark), E5100, 12 μm) were overlapped, folded in half so that the seal layers of the laminated sealant film faced each other, and heat-sealed using a thermal gradient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., model: HG-100-2) at a sealing pressure of 0.2 MPa, a sealing time of 1.0 second, and a heat-sealing temperature of 50 to 170 ° C. at 5 ° C. intervals. The heat-sealed sample was cut into strips with a heat-seal width of 15 mm and set in a universal material testing machine (Instron Japan Company Limited, 68TM-5 model). The maximum strength of the peeled seal between the seal layers at a speed of 200 mm / min was measured with n = 3, and the heat-sealing strength and heat-sealing temperature at each temperature were plotted. The heat seal temperature at which the strength reached 4.9 N / 15 mm was read from a graph connecting each plot with a straight line, and this was taken as the flat seal initiation temperature.

[0063] (Low-temperature sealing effect of flat seal initiation temperature) The low-temperature sealing effect of the flat seal initiation temperature was evaluated by the difference (°C) in the flat seal initiation temperature, based on the flat seal initiation temperature in Comparative Example 3 described below. Specifically, the low-temperature sealability evaluation for Example 1 was made as follows: (flat seal initiation temperature in Comparative Example 3: 160°C) - (flat seal initiation temperature in Example 1: 60°C) = 100°C.

[0064] (Preparation of Laminated Product) A laminated product of a laminated sealant film and a biaxially oriented polypropylene film (Pylen (registered trademark), P2161, 20 μm, manufactured by Toyobo Co., Ltd.) was prepared as follows: First, a dry laminating adhesive (TM569, CAT-10L, manufactured by Toyo-Morton Co., Ltd.) was applied to the corona surface of the biaxially oriented polypropylene film at a solid content of 3 g / m. ２ The solvent was evaporated and removed in an oven at 80° C., and then the corona surface of the laminated sealant film and the adhesive-coated surface were nipped and laminated with a temperature-controlled roll at 60° C. This laminated body was left to stand at 40° C. for 2 days.

[0065] (Sealing Initiation Temperature) This laminated laminate was made into bags using a horizontal pillow packaging machine (FW3301 II / B BD100, manufactured by Fujikikai Co., Ltd.). The conditions were set to a cut length of 250 mm, a height of 45 mm, and a rotation speed of 40 rpm. A sponge scrubber (Kikuron Co., Ltd., Kikuron A (size: 75 × 115 × 36 mm)) was used as the contents. The center seal and end seal portions were kept at the same temperature, and the temperature was lowered in 5°C increments from 170°C. For evaluation, one bag was first cut into two so that two complete end seals were obtained. Next, several drops of an evaluation liquid (self-recording ink RED1812E, manufactured by Kobayashi Create Co., Ltd.) were placed in each half bag. The bag was then visually evaluated by rubbing it with a finger to determine whether the evaluation liquid penetrated through the overlapping portion between the center seal and end seal. The lowest heat seal temperature at which the test liquid did not penetrate was determined as the seal initiation temperature.

[0066] (Low-temperature sealing effect of sealing start temperature) The low-temperature sealing effect of sealing start temperature was evaluated by the difference (°C) between the sealing start temperature in Comparative Example 3 described below and the sealing start temperature in Comparative Example 3. Specifically, the low-temperature sealability evaluation for Example 1 was calculated as (sealing start temperature in Comparative Example 3: 160°C) - (sealing start temperature in Example 1: 135°C) = 25°C.

[0067] The effect of low-temperature sealing at the sealing start temperature is explained below. A horizontal pillow packaging machine for packaging foods and other items is equipped with a center sealer and an end sealer. The end sealer, located downstream, seals and cuts the end seal portions, located upstream and downstream of the packaged item, of the tubular film conveyed by the center sealer in the flow direction. The center sealer is equipped with a pair of conveying rollers and a pair of heating rollers. The tubular film is conveyed by sandwiching the center seal portion, which is where both ends of the downstream width direction meet. The pair of heating rollers located downstream sandwich and heat the center seal portion of the conveyed tubular film. The center seal portion of the tubular film is heated and pressurized by the pair of heating rollers, thereby being thermally bonded. The time required for heating and pressurizing by the pair of heating rollers in the center seal portion is significantly shorter than the time required for heating and pressurizing by the end sealer, which seals the end seal portion using a box motion mechanism or the like. Furthermore, there is a demand for faster operation of horizontal pillow packaging machines, and when the operating speed of a horizontal pillow packaging machine is increased, the rotation speed of both heating rollers also increases, further shortening the heating and pressurizing time. For example, with regard to the low-temperature sealing effect at the sealing start temperature, the bag-making speed in Example 1 is approximately five times faster than in Comparative Example 3. Also, even if the heating temperature of the pair of heating rollers is set high to increase the seal strength of the center seal, there is a sufficient difference in melting point between the base film and the film, so there is no slight melting of the film surface due to heating, and the molten film does not adhere to the surface of the heating roller, reducing the frequency of cleaning the heating roller.

[0068] (Hot tack temperature) The sealant surfaces of the laminated sealant films were placed face to face, and the temperature was 60 to 170°C in 5°C intervals, and the pressure was 2 kgf / cm ２ After heat sealing for 1 second at a pressure of 1000 kJ / s, a load of 46 g was applied and the distance the sealed portion peeled off was measured. The device used was a HEAT SEAL TESTER, TP-701-B, manufactured by Tester Sangyo Co., Ltd. The temperature at which the peeled distance of the sealed portion was 20 mm or less was defined as the hot tack temperature.

[0069] (Low-temperature sealing effect of hot tack temperature) The low-temperature sealing effect of the hot tack temperature is evaluated by the difference in hot tack temperature (°C) based on the hot tack temperature in Comparative Example 3 described below. Specifically, the evaluation of the low-temperature sealing effect of Example 1 is (hot tack temperature in Comparative Example 3: 165°C) - (hot tack temperature in Example 1: 65°C) = 100°C.

[0070] (Burst Strength) A horizontal pillow packaging machine (manufactured by Fujikikai Co., Ltd., FW3301 II / B BD100) was used, with a cut length of 250 mm, a height of 45 mm, and a rotation speed of 40 rpm. A sponge scrubber (manufactured by Kikuron Co., Ltd., Kikuron A (size: 75 x 115 x 36 mm)) was used as the contents, and the temperatures of the center seal portion and the end seal portion were set as the sealing start temperatures. A laminated laminated sealant film was produced into a bag. Evaluation was performed using burst strength (JIS Z0238 Test method for heat-sealed flexible packaging bags and semi-rigid containers). Burst strength was measured using a seal strength / burst strength measuring instrument (manufactured by Sun Scientific Co., Ltd., SEAL TESTER, FKT-100-J).

[0071] (Tensile modulus) Measurement was performed under the following conditions in accordance with JIS K7127. First, the tensile modulus of the laminate in the machine direction (MD) and the direction transverse to the film machine direction (TD) was measured three times with a sample length of 100 mm, a sample width of 15 mm, a chuck distance of 20 mm, and a speed of 200 mm / min, and the average value was taken as the tensile modulus in each direction.

[0072] (Delamination) When measuring the flat seal initiation temperature, hermetic seal initiation temperature, or burst strength, delamination of the laminated sealant film was evaluated as occurring if delamination occurred between the seal layer and the intermediate layer and / or between the intermediate layer and the laminate layer.

[0073] (Appearance Unevenness) Appearance unevenness of the laminated sealant film was evaluated by visually inspecting the film for the presence or absence of appearance defects such as layer misalignment, spots, and unevenness.

[0074] (Haze) The haze of the laminate sealant film was measured in accordance with JIS K7105 using a turbidity meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: ZE2000).

[0075] (Static and Dynamic Friction Coefficients) The static and dynamic friction coefficients were determined in accordance with JIS K7125 under the following conditions at 23°C and 65% RH. The load was 0.5 kgf and the tensile speed was 200 mm / min. The measurement surfaces were as follows, and the measurement device used was a TENSILON STM-T-50BP manufactured by Toyo Baldwin Co., Ltd. (B / B) Between the opposing seal layer surfaces of the laminate sealant film itself, i.e., between the seal layer surfaces. (F / B) Between the opposing seal layer surfaces of the laminate sealant film itself and the laminate layer surface. (CP / CP) Between the opposing seal layer surfaces of the laminate sealant film, i.e., between the seal layer surfaces. (OP / CP) Between the laminate layer surface of the laminate sealant film and the surface of the biaxially oriented polypropylene film.

[0076] (Polypropylene-based resin) The following resins were used as polypropylene-based resins: 1) WF836DG3 (manufactured by Sumitomo Chemical Co., Ltd., Noblene (registered trademark), homopropylene, melting point 158°C, melt flow rate 7.0 g / 10 min, tensile modulus 1,500 MPa) 2) FL8115A (manufactured by Sumitomo Chemical Co., Ltd., Noblene (registered trademark), propylene-ethylene-butene random copolymer, melting point 148°C, melt flow rate 7.0 g / 10 min, tensile modulus 1,000 MPa) 3) FL6632G (manufactured by Sumitomo Chemical Co., Ltd., Noblene (registered trademark), propylene-ethylene-butene random copolymer, melting point 138°C, melt flow rate 6.0 g / 10 min, tensile modulus 1,100 MPa) 4) FL6745A (manufactured by Sumitomo Chemical Co., Ltd., Noblen (registered trademark), propylene-ethylene-butene random copolymer, melting point 130°C, melt flow rate 6.0 g / 10 min, tensile modulus 700 MPa) 5) S131 (manufactured by Sumitomo Chemical Co., Ltd., Noblen (registered trademark), propylene-ethylene-butene random copolymer, melting point 132°C, melt flow rate 1.5 g / 10 min, tensile modulus 650 MPa)

[0077] (Polyethylene Resin) The following resin was used as the polyethylene resin: 1) FV405 (manufactured by Sumitomo Chemical Co., Ltd., Sumikathene (registered trademark) E, linear low-density polyethylene resin, melting point 118°C, melt flow rate 3.8 g / 10 min, flexural modulus 220 MPa)

[0078] (1-Butene Copolymer) The following copolymers were used as the 1-butene copolymer: 1) BL2481M (manufactured by Mitsui Chemicals, Inc., Tafmer (registered trademark), propylene-butene random copolymer, melting point 58°C, melt flow rate 8.0 g / 10 min, tensile modulus 200 MPa) 2) BL2491M (manufactured by Mitsui Chemicals, Inc., Tafmer (registered trademark), propylene-butene random copolymer, melting point 100°C, melt flow rate 8.0 g / 10 min, tensile modulus 260 MPa) 3) BL3110M (manufactured by Mitsui Chemicals, Inc., Tafmer (registered trademark), ethylene-butene random copolymer, melting point 110°C, melt flow rate 2.0 g / 10 min, tensile modulus 280 MPa) 4) XM7070 (Mitsui Chemicals, Inc., Tafmer (registered trademark), propylene-butene random copolymer, melting point 75°C, melt flow rate 7.0 g / 10 min, tensile modulus 290 MPa) 5) XM7080 (Mitsui Chemicals, Inc., Tafmer (registered trademark), propylene-butene random copolymer, melting point 83°C, melt flow rate 7.0 g / 10 min, tensile modulus 390 MPa) 6) XM7090 (Mitsui Chemicals, Inc., Tafmer (registered trademark), propylene-butene random copolymer, melting point 98°C, melt flow rate 7.0 g / 10 min, tensile modulus 520 MPa) 7) A-4085S (Mitsui Chemicals, Inc., Tafmer (registered trademark), ethylene-butene random copolymer, melting point 66°C, melt flow rate 6.7 g / 10 min, tensile modulus 80 MPa)

[0079] (Anti-blocking agent) The following particles were used as the anti-blocking agent: 1) Synthetic silica: KMP130-2 (silica, average particle size 2 μm, manufactured by Shin-Etsu Chemical Co., Ltd.) 2) Synthetic silica: KMP130-4 (silica, average particle size 4 μm, manufactured by Shin-Etsu Chemical Co., Ltd.) 3) Ultra-high molecular weight polyethylene particles: PM200 (average particle size 10 μm, manufactured by Mitsui Chemicals, Inc.)

[0080] (Organic Lubricant) The following compounds were used as organic lubricants: 1) Erucic acid amide: Brand name Diamid L-200 (melting point 81°C, manufactured by Mitsubishi Chemical Corporation) 2) Behenic acid amide: Brand name D1007 (melting point 110°C, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0081] (Masterbatches) 1) Silica masterbatch (M1): Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. was mixed with silica (KMP-130-2 manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 2 μm) to prepare a masterbatch containing 15% by mass of silica. 2) Silica masterbatch (M2): Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. was mixed with silica (KMP-130-4 manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 4 μm) to prepare a masterbatch containing 12% by mass of silica. 3) Ultra-high molecular weight polyethylene particle masterbatch (M3): Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. was mixed with ultra-high molecular weight polyethylene particles (Mipelon PM200 manufactured by Mitsui Chemicals, Inc., average particle size 10 μm) to prepare a masterbatch containing 10% by mass of ultra-high molecular weight polyethylene particles. 4) Erucamide masterbatch (M4): A masterbatch containing 5% by mass of erucamide was prepared by mixing erucamide with Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. 5) Behenamide masterbatch (M5): A masterbatch containing 2% by mass of behenamide was prepared by mixing behenamide with Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd.

[0082] Example 1: The laminate layer was made from WF836DG3, the intermediate layer from FL6745A, and the seal layer from BL2481M. For the seal layer, a masterbatch was used appropriately to obtain the resins and additives shown in Table 1, and the mixing ratio of each raw material was adjusted to obtain the composition ratio shown in Table 1. In Example 1, the masterbatch was prepared using BL2481M instead of FL6745A. The materials were then melted at 240°C using three extruders, filtered through a sintered filter with a filtration accuracy of 60 μm, and co-extruded into a sheet from a T-die. The laminate layer, intermediate layer, and seal layer were melt-extruded to a thickness ratio of 20:60:20% by volume. The laminate layer, intermediate layer, and seal layer were cooled and solidified on a cooling roll at 30°C, and then wound into a roll at a speed of 20 m / min. A laminate sealant film with a thickness of 30 μm and a laminate layer wet tension of 45 mN / m was obtained.

[0083] A dry laminating adhesive (TM569, CAT-10L, manufactured by Toyo-Morton Co., Ltd.) was applied to the corona surface of a biaxially stretched polypropylene film (Pylen (registered trademark), P2161, 20 μm, manufactured by Toyobo Co., Ltd.) at a solid content of 3 g / m ２ The solvent was evaporated in an oven at 80°C, and then the corona surface of the resulting laminate sealant film and the adhesive-coated surface were nipped between temperature-controlled rolls at 60°C to laminate them. Prior to lamination, the surface of the laminate sealant film on the laminate layer side was subjected to corona treatment. The laminated laminate sealant film was left to stand at 40°C for 2 days. The evaluation results are shown in Table 2.

[0084] Examples 2 to 14 A laminated sealant film was prepared in the same manner as in Example 1, except that a masterbatch was appropriately used to prepare the laminate layer, intermediate layer, and seal layer using the resins and additives shown in Table 1 as raw materials, and then a laminated laminated sealant film was prepared. In Examples in which FL6745A was not used in the seal layer, a masterbatch was prepared using the 1-butene copolymer used in the seal layer instead of FL6745A. The evaluation results are shown in Table 2.

[0085] The laminated sealant films of Examples 1 to 14 did not suffer from interlayer delamination, and furthermore, the flat seal initiation temperature and the hermetic seal initiation temperature could be reduced, demonstrating good low-temperature bag-forming properties.

[0086] Comparative Examples 1 to 15 A laminated sealant film was prepared in the same manner as in Example 1, except that a masterbatch was appropriately used to prepare the laminate layer, intermediate layer, and seal layer using the resins and additives shown in Table 3 as raw materials, and then a laminated laminated sealant film was prepared. In Comparative Examples in which FL6745A was not used in the seal layer, a masterbatch was prepared using a 1-butene copolymer, a propylene-based resin, or a polyethylene-based resin used in the seal layer instead of FL6745A. The evaluation results are shown in Table 4.

[0087] Reference Example 1 A laminated sealant film was prepared in the same manner as in Example 1, except that the laminate layer, intermediate layer, and seal layer were made from the resins and additives shown in Table 3 as raw materials and appropriate masterbatches were used, and then laminated laminated sealant films were produced. The evaluation results are shown in Table 4. The masterbatches used in this reference example were Sumikathene (registered trademark) FV405 manufactured by Sumitomo Chemical Co., Ltd., each containing silica, ultra-high molecular weight polyethylene particles, erucic acid amide, or behenic acid amide.

[0088] The laminate sealant film obtained in Comparative Example 1 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 2 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 3 has high flat sealing temperatures and high sealing temperatures. The laminate sealant film obtained in Comparative Example 4 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 5 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 6 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 7 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 8 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 9 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 10 has a high elastic modulus and a poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 11 had a high elastic modulus and poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 12 had a high elastic modulus and poor low-temperature sealing effect at the sealing temperature. The laminate sealant film obtained in Comparative Example 13 had a high elastic modulus and poor low-temperature sealing effect at the sealing temperature. Furthermore, due to the large melt flow rate ratio between the laminate layer and the intermediate layer, uneven appearance was observed. The laminate sealant film obtained in Comparative Example 14 had a large melt flow rate ratio between the laminate layer and the intermediate layer and poor low-temperature sealing effect at the sealing temperature. Furthermore, uneven appearance was also observed. The laminate sealant film obtained in Comparative Example 15 had a sealing layer made of polyethylene resin, and interlayer delamination was observed. The laminate sealant film obtained in Reference Example 1 was a polyethylene-based laminate sealant film rather than a polypropylene-based one, and had a low elastic modulus, making it unsuitable for high-speed automatic bag production.

[0089] The results are shown in Tables 1 to 4. The content of additives in Tables 1 and 3 indicates the ratio to 100% by mass of resin. In Tables 2 and 4, "resin" means "resin composition."

[0090]

[0091]

[0092]

[0093]

[0094] Because laminated sealant films have excellent low-temperature bag-forming properties, they are suitable as packaging materials for many products, such as foods, beverages, pharmaceuticals, and chemicals. They are particularly suitable for use in automatically forming pillow packaging bags, gusset packaging bags, three-side seal packaging bags, and other bags while packaging the contents.

Claims

1. A laminated sealant film that satisfies all of the following requirements 1) to 7). 1) It comprises at least a laminate layer, an intermediate layer (except when it contains 270 ppm of behenic acid amide), and a seal layer in this order. 2) The laminate layer and the intermediate layer each comprise a polypropylene-based resin composition, the seal layer comprises a resin composition containing a 1-butene copolymer, and the polypropylene-based resin composition of the laminate layer contains a polypropylene-based resin in a content of more than 97% by mass. 3) The ratio of the melt flow rate of the polypropylene resin composition of the laminate layer to the melt flow rate of the polypropylene resin composition of the intermediate layer is 0.6 or more and 2.0 or less. 4) The ratio of the melt flow rate of the polypropylene resin composition of the intermediate layer to the melt flow rate of the resin composition containing a 1-butene copolymer of the sealing layer is 0.6 or more and 3.5 or less. 5) The polypropylene resin composition of the laminate layer, the polypropylene resin composition of the intermediate layer, and the resin composition containing a 1-butene copolymer of the seal layer each have a melt flow rate of 1 g / 10 min (load 2.16 kgf) or more and 9 g / 10 min (load 2.16 kgf) or less, respectively. 6) The melting point of the resin composition containing the 1-butene copolymer in the sealing layer is 50°C or higher and 140°C or lower. 7) The tensile modulus in the longitudinal direction is 600 MPa or less.

2. 2. The laminate sealant film according to claim 1, wherein the polypropylene-based resin composition of the intermediate layer contains a polypropylene-based resin, and the polypropylene-based resins of the laminate layer and the intermediate layer are each a propylene random copolymer.

3. 3. The laminate sealant film according to claim 1, wherein the film has a main peak of melting point of 120°C or higher and 160°C or lower.

4. 3. The laminated sealant film according to claim 1, wherein the coefficient of static friction between the surfaces of the sealing layer is 1.0 or less.

5. 3. The laminated sealant film according to claim 1, wherein the coefficient of dynamic friction between the surfaces of the sealing layer is 1.0 or less.

6. 3. The laminate sealant film of claim 1 or 2, wherein the sealing layer comprises silica.

7. 3. The laminate sealant film of claim 1, wherein the sealing layer comprises erucamide.

8. The laminate sealant film according to claim 1 or 2, wherein the sealing layer comprises organic particles.

9. 3. The laminate sealant film according to claim 1, wherein the tensile modulus in the longitudinal direction is 200 MPa or more and 600 MPa or less.