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
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
  • B65D65/38—Packaging materials of special type or form
  • B65D65/40—Applications of laminates for particular packaging purposes

Definitions

• the present invention relates to a laminated sealant film that is resistant to delamination, has excellent appearance, and is easy to form into bags at low temperatures.
• packaging materials have been developed for the contents of many products, including foods, beverages, pharmaceuticals, and chemicals.
• Packaging materials are used in a variety of forms, such as pillow packaging, gusset packaging, and three-sided sealed packaging, and the sealant films used in packaging materials also have the functions required for their applications.
• Sealant films are particularly suited to automatic bag-making processing into pillowcase bags, gusset bags, or three-sided sealed bags while packaging the contents, and the lower the temperature at which heat sealing can be performed, the lower the electricity bill and the easier it is to work, as there is less risk of burns. Heat sealing at low temperatures also increases packaging and bag-making speeds, reduces packaging material waste, and produces neater finished packaging bags.
• conventional sealant films are not prone to delamination, and there were no films that had excellent appearance or low-temperature bag-making capabilities.
• the objective of the present invention is to provide a laminated sealant film that is resistant to delamination, has excellent appearance, and is easy to form into bags at low temperatures.
• the inventors conducted extensive research to achieve this objective, and as a result, by controlling the raw material composition of each layer of the laminated sealant film and the elastic modulus of the entire film, they were able to obtain a laminated sealant film that is less susceptible to interlayer delamination and has excellent appearance and low-temperature bag-making properties.
• the laminated sealant film according to the embodiment is as follows: [1], and preferably any one of [2] to [11].
• a laminated sealant film that satisfies the following requirements 1) to 7).
• a laminated sealant film including 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 each comprise a polypropylene-based resin composition.
• 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 or more and 2.0 or less.
• the ratio of the melt flow rate of the polypropylene resin composition of the seal 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.
• the melt flow rates of the polypropylene resin compositions of the laminate layer, the intermediate layer and the seal layer are 1 g/10 min (load 2.16 kgf) or more and 9 g/10 min (load 2.16 kgf) or less, respectively.
• the melting point of the polypropylene resin composition of the sealing layer is 100° C. or higher and 140° C. or lower.
• the present invention provides a laminated sealant film that is less susceptible to delamination and has excellent appearance and low-temperature bag-making properties. Because the laminated sealant film has excellent low-temperature bag-making properties, it is suitable as a packaging material for many products, such as food, beverages, pharmaceuticals, and chemicals. It is particularly suitable for automatically processing the film into pillow packaging bags, gusset packaging bags, or three-sided sealed packaging bags while packaging the contents.
• the laminate sealant film according to the embodiment satisfies the following 1) to 7).
• a laminated sealant film including 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 each consist of a polypropylene-based resin composition.
• 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 or more and 2.0 or less.
• the ratio of the melt flow rate of the polypropylene resin composition of the seal 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.
• the melt flow rates of the polypropylene resin compositions of the laminate layer, intermediate layer and seal layer are 1 g/10 min (load 2.16 kgf) or more and 9 g/10 min (load 2.16 kgf) or less, respectively.
• the melting point of the polypropylene resin composition of the sealing layer is 100°C or higher and 140°C or lower.
• the laminated sealant film according to the embodiment will be described in detail below.
• the laminated sealant film includes at least a laminate layer, an intermediate layer, and a sealing layer, in this order.
• the laminate layer, the intermediate layer, and the sealing layer will be described in detail below.
• the laminate layer is made of a polypropylene-based resin composition.
• the polypropylene-based resin composition contains a polypropylene-based resin as a main component.
• the term "main component" means that the proportion of the polypropylene-based resin in the polypropylene-based resin composition is 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.
• 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 other than the polypropylene-based resin composition.
• 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 ⁇ -olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc.
• random copolymers and/or block copolymers of propylene and one or more ⁇ -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 ⁇ -olefins are more preferred
• random copolymers of propylene, ethylene, and butene-1 are even more preferred.
• 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.
• 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 3 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 laminate layer is preferably 160°C or less, more preferably 150°C or less, and even more preferably 140°C or less. If the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is 160°C or less, the tensile modulus of the laminate sealant film is easily set to 600MPa or less.
• the lower limit of the melting point (JIS K7121) of the polypropylene resin composition of the laminate layer is preferably 120°C or more, more preferably 125°C or more, and even more preferably 130°C or more.
• the laminate sealant film is less likely to wrinkle when, for example, it is subjected to a retort treatment, and transparency is easily maintained.
• the laminate sealant film when laminated with a stretched polypropylene film, it is possible to obtain a packaging bag made of the same material, and it can be used for applications that could not be handled by a sealant film made of a polyethylene resin. It is useful as a so-called mono-material film.
• the polypropylene resin composition of the laminate layer may contain, in addition to the polypropylene resin, 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 in which ethylene is the main component and other monomers such as propylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1 are copolymerized with vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters, or a mixture thereof.
• These may be crystalline, low-crystalline, or non-crystalline.
• the content of these polymers other than the polypropylene 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.
• the proportion may be 0.1% by mass or more.
• 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, but the peak with the highest melting temperature is the main peak.
• the polypropylene resin composition of the laminate layer preferably contains an antiblocking agent.
• the antiblocking agent 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 silica particles and/or polyethylene particles. In particular, it is preferable to contain silica particles and polyethylene particles.
• the average particle size of the particles is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more, and even more preferably 4 ⁇ m or more. The average particle size of the particles is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less, and even more preferably 10 ⁇ m or less.
• the particle size is the volume average particle size.
• the particle content in the polypropylene resin composition in 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. Also, it 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. Also, if the amount of particles added is 2% by mass or less, there will not be too many protrusions on the surface, and poor appearance and abrasion resistance will be less likely to occur.
• the polypropylene resin composition of the laminate layer preferably contains 0.01% by mass or more and 2.0% by mass or less of 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.
• fatty acid amide is 0.01% by mass or more, blocking between films is not too strong, and the handling properties of the film are easily satisfied.
• the fatty acid amide is 2.0% by mass or less, the seal strength is not likely to decrease.
• fatty acid amide include erucic acid amide, ethylene bis oleic acid amide, and behenic acid amide, and these may be used in combination.
• 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 or more and 2.0 or less, preferably 0.7 or more and 1.6 or less, more preferably 0.8 or more and 1.4 or less, and even more preferably 0.9 or more and 1.2 or less.
• the melt flow rate ratio is within this range, it is less likely to cause appearance defects such as layer misalignment, blemishes, and unevenness.
• the intermediate layer is made of a polypropylene-based resin composition.
• the polypropylene-based resin composition contains a polypropylene-based resin as a main component.
• the term "main component" means that the proportion of the polypropylene-based resin in the polypropylene-based resin composition is 90% by mass or more, and the proportion is preferably 95% by mass or more, 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.
• 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 inevitable impurities other than the polypropylene-based resin composition.
• the polypropylene-based 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 ⁇ -olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc.
• random copolymers of propylene and one or more ⁇ -olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc.
• propylene random copolymers which are random copolymers of propylene and one or more ⁇ -olefins are more preferred, and random copolymers of propylene, ethylene, and butene-1 are even more preferred.
• main component means that the proportion of propylene in the polypropylene-based resin is 90% by mass or more, and the proportion is preferably 95% by mass or more, 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.
• 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 2 g/10 min or less, and even more preferably 3 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.
• the melting point (JIS K7121) of the polypropylene resin composition of the intermediate layer is 150°C or less, it is easy to make the tensile modulus of the laminated sealant film 600 MPa or less.
• 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. If 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, for example, it is retorted, and transparency is also easily maintained. In addition, it can be used in applications that could not be handled by sealant films made of polyethylene resins, such as becoming a mono-material film laminated with OPP film.
• the polypropylene resin composition of the intermediate layer may contain 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 in which ethylene is the main component and other monomers such as propylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, and octene-1 are copolymerized with vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters, or a mixture thereof.
• ethylene homopolymer selected from the group consisting of high-pressure low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene.
• ethylene is the main component and other monomers such as propylene, butene-1, pentene-1,
• These may be crystalline, low-crystalline, or non-crystalline.
• the content of these polymers other than the polypropylene resin 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.
• the proportion may be 0.1% by mass or more.
• the polyethylene resin of the intermediate layer preferably has 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 polyethylene resin of the intermediate layer preferably has a melting point 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, but the peak with the highest melting temperature is defined as the main peak.
• the polypropylene resin composition of the intermediate layer may contain an antiblocking agent.
• the antiblocking agent 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 silica particles and/or polyethylene particles. In particular, it is more preferable to contain silica particles and polyethylene particles.
• the average particle size of the particles is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more, and even more preferably 5 ⁇ m or more.
• the average particle size of the particles is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less, and even more preferably 10 ⁇ m or less.
• the particle size is the volume average particle size.
• 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. 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.
• 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.
• a fatty acid amide include erucic acid amide, ethylene bis oleic acid amide, and behenic acid amide, and these may be used in combination.
• 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 or more and 2.0 or less, preferably 0.7 or more and 1.6 or less, more preferably 0.8 or more and 1.4 or less, and even more preferably 0.9 or more and 1.2 or less.
• the melt flow rate ratio is within this range, it is less likely to cause appearance defects such as layer misalignment, blemishes, and unevenness.
• the seal layer is made of a polypropylene-based resin composition.
• the polypropylene-based resin composition contains a polypropylene-based resin as a main component.
• the term "main component" means that the proportion of the polypropylene-based resin in the polypropylene-based resin composition is 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, and even more preferably 98% by mass or more. The proportion is preferably 100% by mass or less, and more preferably 99% by mass or less.
• the seal 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 seal layer may contain inevitable impurities other than the polypropylene-based resin composition.
• the polypropylene-based resin in the seal 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 ⁇ -olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc.
• random copolymers of propylene and one or more ⁇ -olefins such as ethylene, butene-1, pentene-1, hexene-1, 3-methylbutene-1, 4-methylpentene-1, octene-1, etc.
• propylene random copolymers which are random copolymers of propylene and one or more ⁇ -olefins are more preferred, and random copolymers of propylene, ethylene, and butene-1 are even more preferred.
• main component means that the proportion of propylene in the polypropylene-based resin is 90% by mass or more, and the proportion is preferably 95% by mass or more, 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.
• Polypropylene-based resins have a higher melting point and better transparency than polyethylene-based resins.
• the polypropylene resin composition 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 2 g/10 min or less, and even more preferably 3 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 polypropylene resin composition 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 composition of the sealing layer is 140°C or less, the low-temperature sealability (effect) is excellent.
• the melting point of the polypropylene resin composition of the sealing layer is 140°C or less, the tensile modulus of the laminated sealant film is easily set to 600 MPa or less.
• the polypropylene resin composition 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. If the melting point of the polypropylene resin composition of the sealing layer is 120°C or higher, it will have excellent heat resistance, including retort resistance, and self-supporting properties.
• the polypropylene resin composition of the seal layer preferably contains an antiblocking agent.
• the antiblocking agent 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 silica particles and/or polyethylene particles. In particular, it is preferable to contain silica particles and polyethylene particles.
• the average particle size of the particles is preferably 1 ⁇ m or more, more preferably 2 ⁇ m or more, and even more preferably 4 ⁇ m or more. The average particle size of the particles is preferably 20 ⁇ m or less, more preferably 15 ⁇ m or less, and even more preferably 10 ⁇ m or less.
• the particle size is the volume average particle size.
• the particle content in the polypropylene resin composition 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. Also, it 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. If the amount of particles added is less than 0.1% by mass, it becomes difficult to achieve a surface roughness Ra of 0.1 ⁇ m or more on at least one surface layer, making it difficult to obtain anti-blocking properties and slip properties. Also, by having the amount of particles added be 2% by mass or less, surface protrusions can be reduced, making it easier to prevent the occurrence of abrasion resistance.
• the polypropylene resin composition of the seal layer preferably contains 0.01% by mass or more and 2.0% by mass or less of 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.
• fatty acid amide is 0.01% by mass or more, blocking between films is less, and the handling of the film is easily satisfied.
• the fatty acid amide is 2.0% by mass or less, the seal strength is less likely to decrease.
• fatty acid amide include erucic acid amide, ethylene bis oleic acid amide, and behenic acid amide, and these may be used in combination.
• erucic acid amide has a low melting point, is easy to bleed, and is easy to impart lubricity. It is more preferable that the seal layer contains silica particles as an antiblocking agent and erucic acid amide as an organic lubricant in combination. It is more preferable that the seal layer contains polyethylene particles as an antiblocking agent and erucic acid amide as an organic lubricant in combination. More preferably, the sealing layer contains silica particles and polyethylene particles as an antiblocking agent in combination with erucamide as an organic lubricant.
• laminate layer/intermediate layer/seal layer indicates a structure in which a laminate layer, an intermediate layer, and a seal layer are laminated in order. It is preferable that an intermediate layer is disposed between the laminate layer and the seal layer, since peeling between the laminate layer and the seal layer is unlikely to occur and recycled raw materials can be easily used.
• the raw material composition of the intermediate layer is preferably a raw material composition that is intermediate between the laminate layer and the seal layer in order to make peeling between the laminate layer and the seal layer unlikely to occur.
• the thickness of the laminate layer is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more.
• the thickness of the seal layer is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more.
• the thickness of the intermediate layer is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, even more preferably 10 ⁇ m or more, and particularly preferably 15 ⁇ m or more.
• the thickness of the laminate layer is preferably 12 ⁇ m or less, more preferably 10 ⁇ m or less, and even more preferably 8 ⁇ m or less.
• the thickness of the seal layer is preferably 12 ⁇ m or less, more preferably 10 ⁇ m or more, and even more preferably 8 ⁇ m or less.
• the thickness of the intermediate layer is preferably 30 ⁇ m or less, more preferably 25 ⁇ m or less, and even more preferably 20 ⁇ m 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.
• the ratio of the melt flow rates of the raw resins of adjacent layers is preferably 0.6 or more and 2.0 or less. When the melt flow rate ratio is in this range, it is difficult to cause poor appearance such as layer misalignment, blemishes, and unevenness.
• the main peak of 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 melting point of the film is 120°C or more, the suitability for high retort is 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.
• the difference between the melting point of the polypropylene resin composition of the laminate layer and the melting point of the polypropylene resin composition of the intermediate layer, and the difference between the melting point of the polypropylene resin composition of the intermediate layer and the melting point of the polypropylene resin composition of the seal layer are preferably 30°C or less, more preferably 20°C or less, and even more preferably 10°C or less.
• the resin composition of the laminate layer, intermediate layer, and seal layer may be prepared by blending the above-mentioned resin raw material and various additives as necessary, for example, with a mixer such as a Henschel mixer, a Banbury mixer, or a tumbler mixer. Then, the obtained resin composition can be used to form a film.
• a mixer such as a Henschel mixer, a Banbury mixer, or a tumbler mixer. Then, the obtained resin composition can be used to form a film.
• the mixed resin composition is melted under conditions of, for example, a resin temperature of 110° C. or more and 300° C. or less, and is melt-extruded, for example, from a T-shaped die into a sheet, cast onto a cooling roll, and cooled and solidified to obtain an unstretched sheet.
• a resin temperature of 110° C. or more and 300° C. or less
• a multi-layering device such as a multi-layer feed block, a static mixer, or a multi-manifold die can be used.
• a method in which resins sent out from different flow paths using two or more extruders are laminated into multiple layers using a multi-layer feed block or a multi-manifold die can be mentioned.
• a method in which a melt-kneaded laminated resin composition sheet is melt-extruded and made into a film using a T-die method or an inflation method can be mentioned, but the T-die method is particularly preferable in that the melting temperature of the resin can be increased.
• the lower limit of the cooling roll temperature is preferably 10°C. If it is less than the above, not only may the effect of suppressing crystallization become saturated, but also problems such as condensation may occur, which is not preferable.
• the upper limit of the cooling roll temperature is preferably 70°C or less. If it exceeds the above, crystallization progresses and transparency deteriorates, which is not preferable.
• the temperature of the cooling roll is set to the above range, it is preferable to lower the humidity of the environment near the cooling roll to prevent condensation.
• the surface of the cooling roll is in contact with a high-temperature resin, so the temperature of the cooling roll surface rises.
• the cooling roll is cooled by flowing cooling water through a pipe inside, but it is necessary to reduce the temperature difference in the width direction of the cooling roll surface by ensuring a sufficient amount of cooling water, devising the arrangement of the pipes, and performing maintenance so that sludge does not adhere to the pipes.
• the thickness of the unstretched sheet is preferably in the range of 3 ⁇ m or more and 200 ⁇ m or less.
• the thickness of the film is preferably in the range of 5 ⁇ m or more and 100 ⁇ m or less, and more preferably in the range of 10 ⁇ m or more and 80 ⁇ m or less.
• the resulting unstretched sheet may be stretched, but since stretching to 2.0 times or more will result in a tensile modulus of elasticity exceeding 600 MPa, a stretching ratio of less than 2.0 times is preferred.
• the "longitudinal direction” is the direction corresponding to the flow direction in the film manufacturing process
• the "width direction” is the direction perpendicular to the flow direction in the film manufacturing process.
• the “longitudinal direction” may be abbreviated to the "MD direction” and the “width direction” to the "TD direction”.
• the upper limit of the tensile modulus in the longitudinal direction 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, particularly preferably 520 MPa or less, and most preferably 500 MPa or less.
• the lower limit of the tensile modulus in the longitudinal 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.
• the upper limit of the tensile modulus in the width direction of the laminated 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 especially preferably 440 MPa or less.
• the tensile modulus in the width direction is 580 MPa or less, the low-temperature sealing effect of the sealing start 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.
• the tensile modulus in the width direction is 200 MPa or more, bag making processing is easier to perform.
• the upper limit of the sum of the longitudinal tensile modulus and the width 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. If the longitudinal tensile modulus is 1180 MPa or less, the low-temperature sealing effect at the sealing start temperature is improved.
• the lower limit of the sum of the longitudinal tensile modulus and the width 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. If the longitudinal tensile modulus is 400 MPa or more, bag making processing is easier to perform.
• the upper limit of the average of the longitudinal tensile modulus and the widthwise tensile modulus 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.
• the lower limit of the average of the longitudinal tensile modulus and the widthwise tensile modulus 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.
• the longitudinal tensile modulus is 200 MPa or more, bag making processing is easier to perform.
• 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 are 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 friction coefficient is unlikely to increase.
• the delamination of the laminated sealant film means, for example, the case where delamination occurs between the seal layer and the intermediate layer when the flat seal initiation temperature, the hermetic seal initiation temperature, or the burst strength is measured. If this 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.
• the flat seal start temperature of the laminated sealant film is preferably 100°C or higher and 150°C or lower, more preferably 105°C or higher and 140°C or lower, even more preferably 116°C or higher and 135°C or lower, and even more preferably 121°C or higher and 130°C or lower.
• the flat seal start temperature is preferably set at a lower limit of a temperature 30°C or higher than the melting point of the polypropylene resin of the seal layer and at an upper limit of a temperature 10°C or higher than the melting point of the polypropylene resin of the laminate layer.
• the low-temperature seal effect of the flat seal start temperature is evaluated based on the degree of reduction in heat seal temperature using the heat seal temperature in Comparative Example 1 described later as a reference.
• the low-temperature sealability of the flat seal start temperature is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, even more preferably 20°C or higher, particularly preferably 25°C or higher, and most preferably 27°C or higher.
• the sealing start temperature of the laminated sealant film is preferably 100°C or more and 160°C or less, more preferably 110°C or more and 150°C or less, and even more preferably 120°C or more and 140°C or less.
• the sealing start temperature is preferably set at a lower limit of a temperature 30°C or more lower than the lowest melting point of the polypropylene resin of the seal layer, and at an upper limit of a temperature 10°C or more higher than the highest melting point of the polypropylene resin of the laminate layer.
• the low-temperature sealing effect of the sealing start temperature is evaluated based on the sealing temperature in Comparative Example 1 described later, based on the degree of reduction in the sealing temperature.
• the low-temperature sealability of the sealing start temperature is preferably more than 10°C, more preferably 11°C or more, even more preferably 12°C or more, particularly preferably 15°C or more, and most preferably 20°C or more.
• the hot tack property of the laminated sealant film is preferably such that the peel distance of the tack is 20 mm or less at a lower temperature.
• the hot tack property is said to be good when the seal strength between the sealant films is sufficient even when the resin of the sealant film is in a molten state.
• the low-temperature sealing effect of the hot tack property is evaluated based on the degree of reduction in the heat sealing temperature, based on the hot tack temperature in Comparative Example 1 described later.
• the low-temperature sealability of the hot tack property is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, even more preferably 18°C or higher, and particularly preferably 20°C or higher.
• the sealing layer contains a polypropylene resin that contains an ethylene component, which lowers the melting point, so that the flat seal start temperature and hermetic seal start temperature can be reduced, allowing low-temperature sealing properties to be achieved.
• the laminate layer, intermediate layer, and sealing layer contain polypropylene resin as their main component, making it easier to maintain the heat resistance of the laminated sealant film and reducing delamination between layers.
• the burst strength of the laminated sealant film is evaluated by a bag made from the laminated sealant film.
• a strong burst strength is required for retort sterilization, it is preferably 20 kPa or more, more preferably 25 kPa or more.
• the burst strength of the laminated sealant film may be 35 kPa or less, or may be 30 kPa or less. It has been confirmed that the laminated sealant film achieves a low-temperature sealing effect of at least the flat seal start temperature and the hermetic seal start temperature by optimizing the melting point of the seal layer and the elastic modulus of the film, and also improves its burst strength. This is thought to be because the bag becomes easier to deform by optimizing the elastic modulus in particular, and the burst strength is improved.
• the static and dynamic friction coefficients 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.
• a static and/or dynamic friction coefficient of 2.0 or less the slipperiness between the films is sufficient, and the handling property as a packaging material is improved.
• the melting point of the resin was measured using a differential scanning calorimeter (DSC60, manufactured by Seiko Instruments Inc.) in accordance with JIS K7121. Specifically, about 5 mg of the sample was packed in 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 maximum melting endothermic peak temperature 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.
• 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 dispersion was added to isotone (physiological saline) and further dispersed using an ultrasonic disperser, after which the particle size distribution was obtained using the Coulter counter method and the volume average particle size was calculated.
• the refractive index was 1.30 for physiological saline, 1.457 for synthetic silica and diatomaceous earth, and 1.54 for polyethylene.
• the heat-sealed sample was cut into strips so that the heat seal width was 15 mm, and set in a universal material testing machine (Instron Japan Co., Ltd., 68TM-5 type), and the maximum strength at which the seal layers were peeled off at a speed of 200 mm / min was measured with n number 3, and the heat seal strength and heat seal temperature at each temperature were plotted.
• the heat seal temperature at which 4.9 N / 15 mm was obtained was read from a graph connecting each plot with a straight line, and this was taken as the flat seal start temperature.
• a laminate of a laminated sealant film and a biaxially oriented polypropylene film (Pylen (registered trademark), P2161, 20 ⁇ m, manufactured by Toyobo Co., Ltd.) was prepared as follows. First, a dry lamination adhesive (TM569, CAT-10L, manufactured by Toyo-Morton Co., Ltd.) was applied to the corona surface of the biaxially oriented polypropylene film so as to have a solid content of 3 g/ m2 , and the solvent was removed by volatilization in an oven at 80°C. After that, 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 laminated sealant film was left to stand at 40°C for 2 days.
• a dry lamination adhesive TM569, CAT-10L, manufactured by Toyo-Morton Co., Ltd.
• the laminated laminated sealant film was made into a bag using a horizontal pillow packaging machine (manufactured by Fujikikai Co., Ltd., FW3301 II/B BD100). The conditions were set to a cut length of 250 mm, height of 45 mm, and rotation speed of 40 rpm, and a sponge scrubber (manufactured by Kikuron Co., Ltd., Kikuron A (size: 75 x 115 x 36 mm)) was used as the content.
• the bag was made at the same temperature for the center seal part and the end seal part, and the temperature was lowered from 170 ° C. in 5 ° C. intervals.
• the evaluation For the evaluation, first, one bag was cut into two so that two complete end seal parts were obtained. Next, several drops of evaluation liquid (manufactured by Kobayashi Create Co., Ltd., self-recording ink RED1812E) were placed in each half bag, and the bag was visually evaluated by stroking it with a finger to see whether the evaluation liquid penetrated through the overlapping part of the center seal part and the end seal part. The lowest heat seal temperature at which the evaluation liquid did not penetrate was determined as the hermetic seal initiation temperature.
• evaluation liquid manufactured by Kobayashi Create Co., Ltd., self-recording ink RED1812E
• the laminated laminate sealant films were laminated with the sealant surfaces facing each other, and heat-sealed for 1 second at temperatures of 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, and 170°C under a pressure of 2 kgf/cm2, and then a load of 46 g was applied to measure the distance at which the seal portion peeled off.
• the device used was a HEAT SEAL TESTER, TP-701-B, manufactured by Tester Sangyo Co., Ltd. The temperature at which the peeling distance of the seal portion became 20 mm or less was taken as the hot tack temperature.
• the measurements were performed under the following conditions in accordance with JIS K7127. First, the tensile modulus of the laminated sealant film in the machine direction (MD) and the direction perpendicular to the 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.
• the appearance unevenness of the laminated sealant film was evaluated by visually checking the presence or absence of appearance defects called layer misalignment, spots, and unevenness, which are not uniform in appearance of the film.
• the laminated sealant film was measured in accordance with JIS K7105 using a turbidity meter (manufactured by Nippon Denshoku Industries Co., Ltd., model: ZE2000).
• CP/CP The opposing seal layer surface and seal layer surface of the laminated sealant film in the laminated laminated sealant film, i.e., the seal layer surfaces.
• OP/CP The laminate layer surface of the laminated sealant film and the surface of the biaxially oriented polypropylene film.
• Polyethylene resin The following resins were used as the polyethylene resins. 1) FV405 (manufactured by Sumitomo Chemical Co., Ltd., Sumikathene (registered trademark) E, linear low-density polyethylene resin, melting point 118°C, melt flow rate 3.8g/10min, flexural modulus 220MPa)
• the following particles were used as the antiblocking agent. 1) Synthetic silica: KMP130-2 (average particle size 2 ⁇ m, manufactured by Shin-Etsu Chemical Co., Ltd.) 2) Synthetic silica: KMP130-4 (average particle size 4 ⁇ m, manufactured by Shin-Etsu Chemical Co., Ltd.) 3) Ultra-high molecular weight polyethylene particles: PM200 (average particle size 10 ⁇ m, manufactured by Mitsui Chemicals, Inc.)
• 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.)
• Ultra-high molecular weight polyethylene particle master batch 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 ⁇ m) to prepare a master batch containing 10% by mass of ultra-high molecular weight polyethylene particles.
• Erucamide master batch Erucamide was mixed with Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. to prepare a master batch containing 5% by mass of erucamide.
• Behenic acid amide master batch Behenic acid amide was mixed with Noblen (registered trademark) FL6745A manufactured by Sumitomo Chemical Co., Ltd. to prepare a master batch containing 2% by mass of behenic acid amide.
• Example 1 The laminate layer was made of WF836DG3, and the intermediate layer and the seal layer were made of FL6745A.
• the seal layer was made of the resin and additives shown in Table 1, which were melted at 240°C in each of three extruders, filtered through a sintered filter with a filtration accuracy of 60 ⁇ m, and then co-extruded from a T-die into a sheet.
• the laminate layer, intermediate layer, and seal layer were melt-extruded so that the thickness ratio was 20:60:20% by volume, cooled and solidified with a cooling roll at 30°C, and then wound up into a roll at a speed of 20 m/min to obtain a laminate sealant film with a thickness of 30 ⁇ m and a wet tension of 45 mN/m for the laminate layer.
• a dry lamination adhesive (TM569, CAT-10L, Toyo-Morton Co., Ltd.) was applied to the corona surface of a biaxially oriented polypropylene film (Pylen (registered trademark), P2161, 20 ⁇ m, manufactured by Toyobo Co., Ltd.) so as to have a solid content of 3 g/ m2 , and the solvent was removed by volatilization in an oven at 80 ° C., and then the corona surface of the obtained laminated sealant film and the adhesive-coated surface were nipped and laminated on a temperature-controlled roll at 60 ° C. Before the lamination, a corona treatment was applied to the surface of the laminate layer side of the laminated sealant film. This laminated laminated sealant film was left to stand at 40 ° C. for 2 days. The evaluation results are shown in Table 2.
• Example 2 The laminate layer, intermediate layer, and seal layer were prepared by obtaining a laminate sealant film in the same manner as in Example 1, except that a master batch was appropriately used to make the resin and additives shown in Table 1 as raw materials, and then laminating the laminate sealant film.
• the evaluation results are shown in Table 2.
• the laminated sealant films of Examples 1 to 10 showed good appearance without delamination or uneven appearance. Furthermore, the flat seal start temperature and hermetic seal start temperature could be reduced, and good low-temperature bag making properties were demonstrated.
• the laminated sealant film obtained in Comparative Example 1 has a high flat seal temperature and a high hermetic seal temperature.
• the laminated sealant film obtained in Comparative Example 2 has a low melting point of the sealing layer, but the low-temperature effect at the flat sealing temperature is insufficient, and the elastic modulus is high, resulting in a poor low-temperature sealing effect at the hermetic sealing temperature.
• the laminated sealant film obtained in Comparative Example 3 has a low melting point of the sealing layer but an insufficient low-temperature effect at the flat sealing temperature, and also has a low elastic modulus but an insufficient low-temperature sealing effect at the hermetic sealing temperature.
• the laminated sealant film obtained in Comparative Example 4 has a low melting point of the sealing layer and a sufficient low-temperature effect at flat sealing temperatures, but has a high elastic modulus and is inferior in low-temperature sealing effect at hermetic sealing temperatures.
• the laminated sealant film obtained in Comparative Example 5 had a low elastic modulus but a high melting point of the sealing layer, and was inferior in low-temperature sealing effect at both the flat sealing temperature and the hermetic sealing temperature.
• the laminated sealant film obtained in Comparative Example 6 had a large melt flow rate ratio between the intermediate layer and the seal layer, and therefore had uneven appearance.
• the sealing layer was made of a polyethylene resin, delamination was observed between the sealing layer and the intermediate layer.
• the laminated sealant film obtained in Comparative Example 8 has a low melting point of the sealing layer but an insufficient low-temperature effect at the flat sealing temperature, and also has a low elastic modulus but an insufficient low-temperature sealing effect at the hermetic sealing temperature.
• the laminated sealant film obtained in Comparative Example 9 had a low melting point of the seal layer, but the low-temperature effect at the flat seal temperature was insufficient, and the elastic modulus was also low, but the low-temperature sealing effect at the hermetic seal temperature was also insufficient. Furthermore, the melt flow rate ratio of the laminate layer and the intermediate layer was large, so that the appearance was uneven.
• the laminated sealant film of the present invention has excellent low-temperature bag-making properties, making it suitable as a packaging material for many products, such as food, beverages, medicines, and chemicals. It can be particularly well suited for use in automatically processing pillowcase packaging bags, gusset packaging bags, and three-sided sealed packaging bags while packaging the contents.

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