JP7395317B2 - laminate - Google Patents

Description

The present invention relates to a laminate including a sealant film and a base material, which contains a high content of a propylene copolymer, and has excellent low-temperature heat-sealing properties and blocking resistance.

Crystalline polypropylene film is widely used as a heat-seal packaging film. Crystalline polypropylene film has excellent rigidity and heat resistance, but because the heat sealing temperature is high, the heat sealing property is usually improved by laminating a sealant layer.

As sealant films for packaging materials, compositions made by blending propylene copolymers with ethylene copolymers and films using only ethylene copolymers are widely used. For example, Patent Document 1 describes a laminate with excellent low-temperature heat sealability that includes a sealant film containing a polypropylene resin, an ethylene/α-olefin random copolymer, and a 1-butene/α-olefin random copolymer. has been done.

Japanese Patent Application Publication No. 11-221884

As mentioned above, propylene copolymers have poor low-temperature sealing properties and do not have sufficient blocking resistance. Furthermore, although ethylene copolymers have excellent low-temperature sealing properties, they do not have sufficient blocking resistance. On the other hand, packaging films are also required to reduce manufacturing costs.

The present invention provides a material whose main component is a propylene copolymer, which has excellent low-temperature heat-sealability, and which can also achieve both physical properties such as low-temperature heat-sealability and blocking resistance, as well as a reduction in manufacturing costs. The purpose is to

The present invention relates to, for example, the following [1] to [8].
[1] Contains a sealant film that satisfies requirements (1) to (3) below and a base film that meets requirement (4), when the total mass of the sealant film and base film is 100% by mass A laminate containing 70% by mass or more of a propylene (co)polymer and/or a 1-butene (co)polymer.
(1) The sealant film has at least a heat-adhesive layer containing an olefin (co)polymer (a-2) having a melting point of 30° C. or more and less than 120° C.
(2) The heat sealing strength at 110° C. when the heat-sealing layers are bonded together is 10 N/15 mm or more.
(3) The sealant film is a non-stretched film.
(4) The base film is at least one selected from unstretched polypropylene films and biaxially oriented polypropylene films.
[2] The laminate according to [1], wherein the olefin (co)polymer (a-2) includes at least a propylene/α-olefin copolymer and a 1-butene/α-olefin copolymer.
[3] In addition to the olefin-based (co)polymer (a-2), the heat-sealable layer contains an olefin-based (co)polymer (a-1) having a melting point of 120° C. or higher and 170° C. or lower. The laminate according to [1] or [2].
[4] The laminate according to [3], wherein the olefin (co)polymer (a-1) is a propylene (co)polymer.
[5] The method according to any one of [1] to [4], wherein at least one film selected from the sealant film and the base film includes at least one layer selected from a printing layer, a barrier layer, and an embossing layer. laminate.
[6] The method for producing a laminate according to any one of [1] to [5], wherein at least one film selected from the sealant film and the base film includes a barrier layer, wherein the barrier layer is formed by metal vapor deposition. A method for producing a laminate, comprising the steps of: forming the sealant film as a single layer in the sealant film or the base film by a coating method or coextrusion method; and laminating the sealant film and the base film.
[7] A package formed from the laminate according to any one of [1] to [5].
[8] A molded article that is a recycled product of the laminate according to any one of [1] to [5] or the package according to claim 7.

The laminate of the present invention has a high content of propylene copolymer, has excellent low-temperature heat-sealing properties, and can achieve both physical properties such as low-temperature heat-sealability and blocking resistance, as well as a reduction in manufacturing costs. can.

The laminate of the present invention includes a sealant film and a base film. The laminate of the present invention has a structure in which a sealant film and a base film are laminated. The sealant film is a film that imparts heat sealability to the laminate of the present invention, and the base film is a film that holds the sealant film.

The sealant film satisfies the following requirements (1) to (3).
(1) The sealant film has at least a heat-adhesive layer containing an olefin (co)polymer (a-2) having a melting point of 30° C. or more and less than 120° C.

In the present invention, the term "(co)polymer" is a concept that includes homopolymers and copolymers.
The thermal adhesive layer is a layer that imparts thermal adhesive properties to the sealant film. The thermal adhesive layer contains an olefin (co)polymer (a-2) having a melting point of 30°C or more and less than 120°C.

The olefin-based (co)polymer (a-2) includes homopolymers of α-olefins, copolymers of the α-olefins with other α-olefins, and monomers other than the α-olefins and α-olefins. Examples include copolymers with Specifically, the olefin-based (co)polymer (a-2) includes an ethylene homopolymer and a copolymer of ethylene and an α-olefin having 3 or more carbon atoms (ethylene/α-olefin copolymer). ), propylene (co)polymers such as propylene homopolymers, and copolymers of propylene and α-olefins having 4 or more carbon atoms (propylene/α-olefin copolymers); Examples include a copolymer of 1-butene and an α-olefin having 5 or more carbon atoms (1-butene/α-olefin copolymer). Among these, propylene/α-olefin copolymer, 1-butene/α-olefin copolymer and ethylene/α-olefin copolymer are more preferred.

α-olefins having 3 or more carbon atoms that copolymerize with ethylene include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, Examples include α-olefins having 3 to 20 carbon atoms such as 1-decene, 1-dodecene, and 1-tetradecene. Examples of the α-olefin having 4 or more carbon atoms to be copolymerized with propylene include the aforementioned α-olefins other than propylene. Examples of the α-olefin having 5 or more carbon atoms to be copolymerized with 1-butene include the aforementioned α-olefins other than propylene and 1-butene.

The olefin (co)polymer (a-2) may be one type of (co)polymer or may be a copolymer of two or more types.
The olefin (co)polymer (a-2) preferably contains at least a propylene/α-olefin copolymer and a 1-butene/α-olefin copolymer. Although propylene/α-olefin copolymers are generally inexpensive, they do not have sufficient low-temperature sealing properties and blocking resistance. On the other hand, 1-butene/α-olefin copolymers are generally expensive, but have excellent low-temperature sealing properties and blocking resistance. Since the olefin (co)polymer (a-2) contains at least a propylene/α-olefin copolymer and a 1-butene/α-olefin copolymer, it has excellent low-temperature sealing properties and blocking resistance, and , it becomes easy to achieve both physical properties such as low-temperature heat sealability and blocking resistance, and reduction in manufacturing costs.

When the olefin (co)polymer (a-2) contains a propylene/α-olefin copolymer and a 1-butene/α-olefin copolymer, the olefin (co)polymer (a-2) The content ratio of propylene/α-olefin copolymer is preferably 50 to 90% by mass, more preferably 55 to 80% by mass, and the content ratio of 1-butene/α-olefin copolymer is preferably 10 to 90% by mass. The amount is preferably 50% by weight, more preferably 20 to 45% by weight.

More preferably, the olefin (co)polymer (a-2) contains a propylene/ethylene copolymer and a 1-butene/propylene copolymer.
The melting point of the olefin (co)polymer (a-2) is 30°C or higher and lower than 120°C, preferably 40 to 110°C, more preferably 50 to 100°C. When the melting point of the olefin (co)polymer (a-2) is within the above range, a laminate with excellent low-temperature heat sealability can be obtained.

The MFR of the olefin-based (co)polymer (a-2) measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg is preferably 0.1 to 100 g/10 min, more preferably 1 to 20 g. /10min.

The olefin (co)polymer (a-2) is prepared by polymerizing monomers using known polymerization methods such as gas phase method, bulk method, and slurry method in the presence of known catalysts such as Ziegler-Natta catalysts and metallocene catalysts. It can be produced by polymerization. One example of a method for controlling the melting point to be 30°C or higher and lower than 120°C is to control the polymerization conditions such as the amount of monomer feed, and when polymerizing with a Ziegler-Natta catalyst, increase the comonomer content to 20% by mole or more, 50% by mole or more. When polymerizing with a metallocene catalyst, the comonomer content may be controlled to 10 mol% or more and 50 mol% or less, and by this method, a copolymer having a target melting point can be obtained. .

The thermal adhesive layer may contain a (co)polymer other than the olefin (co)polymer (a-2).
There may be two or more heat-adhesive layers, but one layer is preferable.
The sealant film may include layers other than the heat sealing layer.

(2) The heat seal strength at 110° C. when the heat sealing layers are bonded together is 10 N/15 mm or more.
The method for measuring the heat seal strength will be described in detail in Examples.

In the sealant film, the heat sealing strength is 10 N/15 mm or more, preferably 12 N/15 mm or more, more preferably 15 N/15 mm or more. When the heat sealing strength is 10 N/15 mm or more, a laminate having excellent low-temperature heat sealing properties and heat sealing strength can be obtained.
A sealant film satisfying requirement (2) can be obtained by appropriately adjusting the melting point.

(3) The sealant film is a non-stretched film.
The sealant film is an unstretched film that has not been subjected to stretching treatment after being formed as a film. When the sealant film is a non-stretched film, a film that is more flexible and has excellent heat seal strength can be obtained.

The sealant film may contain other resins, tackifiers, weather-resistant stabilizers, heat-resistant stabilizers, antistatic agents, anti-slip agents, anti-blocking agents, lubricants, pigments, dyes, plasticizers, within the range that does not impair the purpose of the present invention. Additives such as antiaging agents, antioxidants, hydrochloric acid absorbers, and antioxidants may be included as necessary.

The base film satisfies requirement (4).
(4) The base film is at least one selected from unstretched polypropylene films and biaxially oriented polypropylene films.

The base film is a polypropylene film. Examples of the polypropylene constituting the polypropylene film include propylene homopolymers and copolymers containing propylene as a main monomer. In the case of a copolymer, it may be a random copolymer or a block copolymer. Monomers that copolymerize with propylene include α-olefins other than propylene, diene compounds, and the like. The propylene content (structural units derived from propylene) in the polypropylene is 85 to 100 mol%, preferably 90 to 99.5 mol%, and the content of other monomers is 0 to 15 mol%, preferably 0.5 ~10 mol%.

Other α-olefins copolymerized with propylene include ethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene. Examples thereof include α-olefins having 2 or 4 to 20 carbon atoms such as 1-dodecene and 1-tetradecene.

The polypropylene has an MFR of preferably 0.1 to 10 g/10 min, more preferably 0.5 to 8 g/10 min, and a melting point ( Tm) is preferably 130 to 165°C, more preferably 135 to 150°C.

Specifically, the polypropylene includes propylene homopolymer, propylene/ethylene random copolymer, propylene/1-butene random copolymer, propylene/1-butene/ethylene random copolymer, propylene/1- Examples include hexene random copolymer, propylene/3-methyl-1-butene random copolymer, propylene/4-methyl-1-pentene random copolymer, and the like. The polypropylene can be used alone or in combination of two or more.

The polypropylene can be produced by polymerizing monomers by a known polymerization method such as a gas phase method, a bulk method, or a slurry method in the presence of a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. .
The polypropylene may be the same (co)polymer as the olefin (co)polymer (a-2) contained in the sealant film.

The base film is at least one selected from an unstretched polypropylene film that is not subjected to a stretching process to a film formed from the polypropylene, and a biaxially stretched polypropylene film obtained by subjecting a film formed from the polypropylene to a biaxially stretching process. As the stretching method, a known method for producing stretched films can be used. Specifically, roll stretching, tenter stretching, tubular stretching, etc. can be mentioned. The stretching ratio is 1.5 to 20 times, usually 2 to 15 times.

The base film may consist of a single layer or a plurality of layers.
The base film may contain other resins, tackifiers, weather stabilizers, heat stabilizers, antistatic agents, anti-slip agents, anti-blocking agents, lubricants, pigments, dyes, plasticizers, anti-aging agents, and hydrochloric acid absorbers. , antioxidants, and other additives.

The laminate of the present invention contains 70% by mass or more of the propylene (co)polymer and/or 1-butene (co)polymer when the total mass of the sealant film and the base film is 100% by mass. include. That is, the laminate of the present invention contains only one of the propylene (co)polymer and the 1-butene (co)polymer when the total mass of the sealant film and the base film is 100% by mass. containing 70% by mass or more of a propylene (co)polymer and a 1-butene (co)polymer in a total of 70% by mass or more. The content of the propylene (co)polymer and/or 1-butene (co)polymer is preferably 80 to 100% by mass, more preferably 90 to 100% by mass. When the laminate of the present invention contains a propylene (co)polymer and/or a 1-butene (co)polymer in the above range, it is preferable from the viewpoint of environmental issues and also has excellent low-temperature heat sealability.

Examples of the propylene (co)polymer include a propylene homopolymer, a copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms, and the like. The α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1 -dodecene, 1-tetradecene, etc.

Examples of the 1-butene (co)polymer include a 1-butene homopolymer, a copolymer of 1-butene and ethylene or an α-olefin having 5 to 20 carbon atoms, and the like. The α-olefins having 5 to 20 carbon atoms include 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1 -Tetradecene, etc. can be mentioned.

The propylene (co)polymer and 1-butene (co)polymer may both be (co)polymers included in the sealant film as an olefin (co)polymer (a-2), It may be a (co)polymer contained in the base film as polypropylene, or a (co)polymer contained in a film other than the sealant film and the base film.

In addition to the olefin-based (co)polymer (a-2), the heat-sealing layer contained in the sealant film contains an olefin-based (co)polymer (a-1) having a melting point of 120°C or higher and 170°C or lower. ) can be included. When the thermal adhesive layer contains the olefin (co)polymer (a-1) in addition to the olefin (co)polymer (a-2), film blocking is less likely to occur during and after film formation.

Examples of the olefin (co)polymer (a-1) include the same (co)polymers as the above-mentioned olefin (co)polymer (a-2).
The olefin (co)polymer (a-1) is more preferably a propylene (co)polymer.

The olefin (co)polymer (a-1) is produced by polymerizing monomers by known polymerization methods such as gas phase method, bulk method, and slurry method in the presence of known catalysts such as Ziegler-Natta catalysts and metallocene catalysts. It can be produced by polymerization. As a method for controlling the melting point to 120°C or higher and 170°C or lower, for example, by controlling the polymerization conditions such as the amount of monomer feed, in the case of polymerization using a Ziegler-Natta catalyst, the comonomer content is less than 20 mol%, and the comonomer content is less than 20 mol%, In the case of polymerization using a system catalyst, there is a method of controlling the comonomer content to less than 10 mol %, and by this method, a copolymer having a target melting point can be obtained.

The thickness of the sealant film is usually 3 to 50 μm, preferably 5 to 25 μm, and the thickness of the base film is usually 15 to 70 μm, preferably 20 to 50 μm. When there are multiple sealant films, it is preferable that each sealant film has the above thickness. The thickness of the entire laminate of the present invention is usually 20 to 100 μm, preferably 25 to 70 μm.

Various layers can be included to impart specific functions to the sealant film and base film. For example, the sealant film and base film can include functional material layers such as a printed layer, a barrier layer, and an embossed layer.

A resin film on which an inorganic compound or an inorganic oxide is vapor-deposited, a metal foil, a coating film of a resin having a special function, a resin film on which a pattern is printed, etc. can be used for the functional material layer.
Here, as the resin film used, it is possible to use the same resin film as the resin film used for the base film, and furthermore, similar plastic compounding agents and additives can be used for other performances. It can be added in any amount depending on the purpose as long as it does not cause any adverse effects.

For example, the resin film may be made using one or more resins selected from the group of resins similar to those for the base film, and may be produced by extrusion, cast molding, T-die, cutting, inflation, etc. It can be manufactured by a conventionally used film forming method or by a multilayer coextrusion film forming method using two or more types of resins. Furthermore, from the viewpoint of the strength, dimensional stability, and heat resistance of the film, it is possible to stretch the film in uniaxial or biaxial directions using, for example, a tenter method or a tubular method.

For example, in a laminate in which at least one film selected from the sealant film and the base film includes a barrier layer, the barrier layer is formed as one layer in the sealant film or the base film by metal vapor deposition, coating, or coextrusion. It can be manufactured by a method for manufacturing a laminate including a step of forming and a step of laminating the sealant film and a base film.

Examples of the embodiment of the laminate include, but are not limited to, a two-layer structure of sealant film/base film and a three-layer structure of sealant film/base film/sealant film. An adhesive layer can also be provided between the sealant film and the base film.

The laminate of the present invention may be manufactured by laminating a sealant film and a base film via an adhesive layer by dry lamination, non-solvent lamination, sand lamination, etc., or by laminating a sealant film and a base film by melt extrusion lamination. It may also be manufactured by laminating films. Among these, dry lamination or melt extrusion lamination is preferred.

As mentioned above, the laminate of the present invention has a high propylene copolymer content, has excellent low-temperature heat-sealing properties, has excellent blocking resistance, and has physical properties such as low-temperature heat-sealing properties and blocking resistance, and low manufacturing cost. It is possible to achieve both.

A package can be obtained from the laminate of the present invention. A package formed from the laminate of the present invention has excellent low-temperature heat sealability. In addition, the package formed from the laminate of the present invention obtained in this way has the same heat sealing strength as conventional products when molded at conventional heat sealing temperatures (for example, over 100°C to 160°C). can be maintained above.

For example, the sealant film layers of the laminate are faced to each other, or the sealant film layer of the laminate film and another film are faced to each other, and then at least a portion of the periphery is formed so as to form a desired container shape from the outer surface side. A container can be manufactured by heat sealing. Moreover, by heat-sealing the entire periphery, a sealed bag-like container can be manufactured. When this bag-like container forming process is combined with the content filling process, the bottom and sides of the bag-like container are heat-sealed, the contents are filled, and the top is then heat-sealed to produce a package. can do. This package can be used in an automatic packaging device for solid materials such as snacks and bread, powder, or liquid materials.

In addition, the contents are filled into a container formed from a laminate or sheet into a cup shape by vacuum forming, pressure forming, etc., a container obtained by injection molding, etc., or a container formed from a paper base material, and then the contents are filled. By covering the laminate of the invention as a lid material and heat-sealing the top or side of the container, a container can be obtained in which the contents are packaged. This container is suitably used for packaging instant noodles, miso, jelly, pudding, snack foods, and the like.

Recycled laminates or packages can also be effectively used. The molded product, which is a recycled product of the laminate or package, makes it possible to reduce the amount of newly polymerized plastic used, and becomes an article that can contribute to reducing environmental impact.

Next, the laminate of the present invention will be described in more detail by showing Examples, but the present invention is not limited thereto.
The materials used in Examples and Comparative Examples are shown below.

rPP-1: Random polypropylene (MFR (230°C, 2.16kg load, according to ASTM D1238): 7g/10min, melting point: 138°C, propylene content: 96 mol%)
BPR-1: 1-butene propylene copolymer (MFR (230°C, 2.16kg load, according to ASTM D1238): 9g/10min, MFR (190°C, 2.16kg load, according to ASTM D1238): 4g /10min, melting point: 100°C, 1-butene content: 85 mol%, propylene content: 15 mol%)
BPR-2: 1-butene propylene copolymer (MFR (230°C, 2.16kg load, according to ASTM D1238): 9g/10min, MFR (190°C, 2.16kg load, according to ASTM D1238): 4g /10min, melting point: 58°C, 1-butene content: 75 mol%, propylene content: 25 mol%)
PER-1: Propylene/ethylene copolymer (MFR (230°C, 2.16kg load, according to ASTM D1238): 8g/10min, MFR (190°C, 2.16kg load, according to ASTM D1238): 3.7g /10min, Vicat softening point: 76.7°C, Shore D hardness: 40, propylene content: 87 mol%, ethylene content: 13 mol%)
Heat seal strength and surface properties such as dynamic friction coefficient and blocking force were measured by the following measurement methods.

[Measurement method of heat seal strength]
The sealant film surfaces of two laminates are overlapped, or two single-layer films are overlapped, and the temperature is 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C. C. or 160.degree. C. for 1 second at a pressure of 0.2 MPa with a seal bar width of 5 mm, and then allowed to cool. Next, test pieces with a width of 15 mm were cut from each test piece obtained by heat sealing, and the peel strength of each test piece was measured when the heat sealed portion was peeled off at a crosshead speed of 300 mm/min. Seal strength.

[Measurement method of dynamic friction coefficient]
The laminate was formed into a strip with a width of 64 mm, the sealant surfaces of the two strip-shaped laminates were placed on top of each other, a 200 g weight was placed on the laminate, one laminate was fixed, and the other laminate was moved at a speed of 200 mm/min. The coefficient of friction was measured by pulling it.

[Method of measuring blocking force]
The laminate was formed into a strip with a width of 200 mm, the sealant surfaces of the two strip-shaped laminates were placed on top of each other, placed in an air oven at 50°C, and a load of 20 kg was applied from the top of the stacked laminate for 3 days. did. Thereafter, the laminate was taken out of the air oven, and the blocking force was measured by peeling the two strip-shaped laminates at a speed of 200 mm/min. Note that the smaller the value of the blocking force, the better the anti-blocking property.

[Example 1]
40 parts by mass of rPP-1, 20 parts by mass of BPR-1 and 40 parts by mass of PER-1 were blended, and silica particles (average particle diameter 3 μm) and erucic acid amide were added as anti-slip agents in a content of 4900 ppm and 2000 ppm, respectively. A resin composition for producing a sealant film was prepared by mixing the following.

Using two extruders connected to T-dies, the resin composition for producing the sealant film and rPP-1 for producing the base film were supplied to each extruder, and the die and resin temperatures were set at 230°C. The extrusion rate of each extruder was adjusted to produce a laminate in which a 50 μm thick unstretched base film and a 20 μm thick unstretched sealant film were laminated by coextrusion molding. Using this laminate, heat seal strength, coefficient of dynamic friction, and blocking force were determined by the measurement method described above. The results are shown in Table 1.

[Examples 2 to 5, Comparative Examples 1 to 6]
A laminate was produced in the same manner as in Example 1, except that the composition of the composition for producing a sealant film was changed to the composition shown in Table 1. Using each of these laminates, heat seal strength, coefficient of dynamic friction, and blocking force were determined by the measurement methods described above. The results are shown in Table 1. The numerical values regarding the laminate in Table 1 indicate parts by mass.

Claims (7)

It contains a sealant film that satisfies the following requirements (1) to (3) and a base film that meets requirement (4), and when the total mass of the sealant film and base film is 100% by mass, propylene A laminate containing 70% by mass or more of a (co)polymer and/or a 1-butene (co)polymer.
(1) The sealant film is made of an olefin (co)polymer (a-1) having a melting point of 120°C or higher and 170°C or lower, and an olefin (co)polymer (a-1) having a melting point of 30°C or higher and lower than 120°C. The olefin (co)polymer (a-2) contains 50 to 90% by mass of propylene/α-olefin copolymer and 1-butene. -Contains 10 to 50% by mass of α-olefin copolymer .
(2) The heat seal strength at 110° C. when the heat sealing layers are bonded together is 10 N/15 mm or more.
(3) The sealant film is a non-stretched film.
(4) The base film is at least one selected from unstretched polypropylene films and biaxially oriented polypropylene films. The olefin (co)polymer (a-2) contains a propylene/ethylene copolymer as the propylene/α-olefin copolymer, and 1-butene as the 1-butene/α-olefin copolymer. - The laminate according to claim 1, containing a propylene copolymer. The laminate according to claim 1 or 2, wherein the olefin (co)polymer (a-1) is a propylene (co)polymer. The laminate according to any one of claims 1 to 3 , wherein at least one film selected from the sealant film and the base film includes at least one layer selected from a printing layer, a barrier layer, and an embossing layer. The method for producing a laminate according to any one of claims 1 to 4 , wherein at least one film selected from the sealant film and the base film includes a barrier layer, the barrier layer being formed by metal vapor deposition, coating, or combination. A method for producing a laminate, comprising the steps of forming a single layer in the sealant film or base film by an extrusion method, and laminating the sealant film and base film. A package formed from the laminate according to any one of claims 1 to 4 . A molded article that is a recycled product of the laminate according to any one of claims 1 to 4 or the package according to claim 6 .