JP7270018B2 - Resin composition, film, laminate, package, and method for producing package - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition, a film, a laminate, a package, and a method for producing the package.

Conventionally, as a film for packaging, the part sealed by heat sealing is different from the so-called easy peel part that can be peeled off even with a relatively weak force, and the so-called tight seal part with relatively strong bonding strength. A configuration that exhibits characteristics is known (see Patent Document 1, for example).
The film described in Patent Document 1 is selected from the group consisting of (1) an ethylene/α,β-unsaturated carboxylic acid copolymer having a melt flow rate of 0.5 to 6 g/10 minutes, and an ionomer thereof. (2) at least one selected from the group consisting of ethylene/α,β-unsaturated carboxylic acid copolymers having a melt flow rate of 10 to 30 g/10 min, and ionomers thereof; and (3 ) A film made of a resin composition containing at least one selected from the group consisting of homopolymers of propylene and copolymers of propylene and one or more α-olefins excluding propylene.

WO2011/152324

In conventional films such as those described in Patent Literature 1, it is desired to further shorten the time until the required sealing properties are exhibited. If it takes a long time to develop the required sealing properties, there is a problem that, for example, product quality control cannot be performed immediately.
An object of the present invention is to provide a resin composition, a film, a laminate, a package, and a method for manufacturing a package, which can express different bonding states immediately after bonding, for example, depending on the temperature at which it is bonded to an object to be bonded. .

The resin composition of one embodiment of the present invention includes at least two polymers having different solubility parameters (δ, hereinafter referred to as sp values) ((cal/cm ³ ) ^1/2 ), and a nucleating agent. , is blended.

In the present invention, since at least two polymers having different sp values are incompatible, resins of other incompatible polymers are scattered like islands in the resin of any one polymer. It has a sea-island structure.
For example, when heat-sealing a film made of the resin composition in which one component (A) of the two polymers has a sea structure and the other component (B) has an island structure, a predetermined temperature range (hereinafter referred to as When heat-sealing is performed in the first temperature range, the non-melted island structure component (B) inhibits the fusion of the molten sea structure component (A). As a result, the heat-sealed portion exhibits a so-called easy peel property in which the sealing strength is relatively weak. When heat-sealed in a second temperature range (a temperature range higher than the first temperature range in which both the component (A) and the component (B) are in a molten state), the melted component (A) and Due to the fusion of both components (B), the heat-sealed portion exhibits a so-called tight seal with a relatively high seal strength. After heat-sealing, crystallization immediately proceeds due to the nucleating agent, and the sealability of the heat-sealed portion is developed in a short period of time.
As described above, in the present invention, by blending a polymer having a different sp value with a nucleating agent, it is possible to exhibit easy-peelability and tight-sealing properties immediately after bonding the film, for example. Furthermore, the first temperature range and the second temperature range can be clearly differentiated from the relationship between the temperature and the layer structure, and the easy peel property and the tight seal property in the article using the resin composition can be easily formed. can.

Here, the sea-island structure is a phase structure showing a mixed state of immiscible resins, and is a state in which one resin is dotted with the other immiscible resin like islands.
Further, for example, bonding of films made of the resin composition is not limited to heat sealing, and includes welding by ultrasonic waves.
Then, the sp value (δ) is calculated according to the calculation method proposed by Fedors. Specifically, Ev (evaporation energy) and V (molar volume) in the table described in "Polym. Eng. Sci., 14 (2), 147-154 (1974)" are obtained, and the following It is calculated based on the formula (1).
δ=(Ev/V) ^1/2 (1)

In the present invention, the absolute value of the difference between the sp values of the at least two types of polymers may be 0.7 or more and 1.2 or less.
In the present invention, by setting the absolute value of the difference in the sp values of the polymers to a predetermined value, it is possible to form an appropriate dispersed state for exhibiting the required sealing properties.
Here, if the absolute value of the sp value difference is less than 0.7, the compatibility of each polymer becomes high, and there is a possibility that a dispersed state for exhibiting the required sealing properties cannot be formed. On the other hand, when the absolute value of the sp value difference is greater than 1.2, the dispersed state of each polymer becomes unstable, and for example, the film-forming properties of the film made of the resin composition become unstable. The moldability of the resin composition may become unstable. Therefore, the absolute value of the sp value difference is preferably set to 0.7 or more and 1.2 or less.

Further, in the present invention, regarding the melt flow rate of the at least two polymers (230° C., under a load of 2160 g) (JIS K7210), the melt flow rate of the polymer exhibiting the sea structure is compared with that of the polymer exhibiting the island structure. can also be configured such that the ratio of the melt flow rate of each is 0.1 or more and 1.2 or less.
In the present invention, by setting the ratio of the melt flow rate (hereinafter referred to as MFR) of the polymer to a predetermined value, it is possible to form an appropriate dispersion state for developing the required sealing properties.
Here, if the ratio of MFR is greater than 1.2, the island portion of the sea-island structure becomes small, and there is a risk that the required sealing properties cannot be achieved. On the other hand, when the ratio of MFR is less than 0.1, the island portion of the sea-island structure becomes large. There is Therefore, it is preferable to set the ratio of MFR to 0.1 or more and 1.2 or less.

Furthermore, in the present invention, the absolute value of the difference in melting points between the at least two polymers may be 35 or more and 70 or less.
In the present invention, by setting the absolute value of the difference in the melting point of the polymer to a predetermined value, heat sealing can be easily performed, for example, according to the temperature relationship between the first temperature region and the melting point.
Here, if the absolute value of the melting point difference is less than 35, the first temperature range becomes narrow, and there is a risk that the control of, for example, the heat sealing temperature for stably exhibiting the desired sealing properties may become complicated. On the other hand, when the absolute value of the melting point difference is higher than 70, for example, when a film made of the resin composition is used as a sealant layer and a laminate obtained by laminating this sealant layer with a base material layer is heat-sealed, the base material layer The melting point of polyolefin resin, nylon resin, polyethylene terephthalate resin, etc. and the second temperature range are close to each other. For this reason, when heat-sealed in the second temperature range, there is a risk of adhesion to the seal bar, or appearance defects such as wrinkles due to shrinkage of the package comprising the laminate. Therefore, the absolute value of the melting point difference is preferably set to 35 or more and 70 or less, more preferably 40 or more and 70 or less.

In the present invention, one of the at least two polymers is a polyolefin polymer, and the blending amount of the polyolefin polymer is 5% by mass or more and 20% by mass or less with respect to the total amount of the composition. The content of the nucleating agent may be 1% by mass or more and 3% by mass or less with respect to the total amount of the composition.
In the present invention, by setting the polyolefin polymer and the nucleating agent in predetermined blending amounts among the polymers, for example, when heat-sealing a film produced from the resin composition, the required Stable sealing properties are obtained.
Here, if the blending amount of the polyolefin polymer is less than 5% by mass with respect to the total amount of the composition, the amount of the polyolefin polymer that inhibits fusion between other polymers when heat-sealed in the first temperature range is small. , there is a risk that the easy peel property will not be expressed. On the other hand, if the blending amount of the polyolefin polymer is more than 20% by mass with respect to the total amount of the composition, fusion bonding of each polymer may be hindered during heat sealing in the second temperature range, and tight sealability may not be exhibited. There is In addition, when the amount of the nucleating agent is less than 1% by mass based on the total amount of the composition, the nucleating action becomes insufficient and the crystallization speed after heat sealing becomes slow, resulting in especially easy peelability. It may take time. On the other hand, when the amount of the nucleating agent is more than 3% by mass based on the total amount of the composition, the nucleating action becomes saturated, so there is a risk that the cost will increase as the amount of the nucleating agent increases. . Therefore, it is preferable that the blending amount of the polyolefin polymer is 5% by mass or more and 20% by mass or less based on the total amount of the composition, and the blending amount of the nucleating agent is 1% by mass or more and 3% by mass or less based on the total amount of the composition. .

A film of one aspect of the present invention is characterized by using the resin composition of the present invention as a raw material.
By using the resin composition of the present invention as a raw material, for example, different seal characteristics, such as easy peel property and tight seal property, can be exhibited immediately after heat sealing at a portion to be heat-sealed. Furthermore, since the first temperature range and the second temperature range can be clearly differentiated, it is possible to easily set different seal characteristics such as easy peel property and tight seal property.

A laminate according to one aspect of the present invention includes a base layer and the film of the present invention laminated on the base layer.
In the present invention, the easy peel property and the tight seal property of the present invention can be easily set to different properties, and films are laminated that can exhibit the different properties immediately after heat sealing. As a result, the desired sealing properties can be stably exhibited immediately after heat sealing, which facilitates quality control of the heat-sealed portion, and can be applied favorably to various types of packaging such as packaging bags, improving versatility.

A package of one aspect of the present invention is a package obtained by superimposing the laminate of the present invention and partially heat-sealing the package, wherein the seal strength after heat-sealing increases with respect to the increase in the heat-sealing temperature. In a saturated first relationship, a first heat-sealed portion formed by heat-sealing the laminate in the temperature range, and a temperature range higher than the first relationship, after heat-sealing for the heat-sealing temperature A second heat-sealed portion formed by heat-sealing the laminate in the temperature range in a second relationship where the maximum value of the seal strength ratio of is 1.3 N / 25 mm / ° C. or more. It is characterized by

In the present invention, when the laminate of the present invention is superimposed and heat-sealed by heating, the first heat-sealed portion formed by heat-sealing in the temperature range (first temperature range) that becomes the first relationship is easy peel show gender. The second heat-sealed portion formed by heat-sealing in the second temperature range (second temperature range), which is higher than the first temperature range, exhibits tight sealability. By having these different sealing characteristics, for example, different foods are stored in one package, the first heat-sealed part is peeled off and the different foodstuffs are mixed, and then the second heat-sealed part is peeled off and mixed food. You can easily cook to take out.
In the second relationship, when the maximum value of the ratio of the seal strength after heat sealing to the heat sealing temperature is smaller than 1.3 N / 25 mm / ° C., in the first relationship, the seal strength after heat sealing to the heat sealing temperature This is because there is a possibility that the difference from the ratio of will become small, making the determination after heat sealing difficult.
Here, the packaging body is not limited to a bag, and various forms such as a container in which a container body and a lid are heat-sealed can be used. In addition, regarding the configuration of the bag, a gusset type having folds on the sides and bottom can also be used.
The saturation of the seal strength after heat-sealing with respect to the rise in heat-sealing temperature means a substantially constant state in which the seal strength after heat-sealing does not change much even if the heat-sealing temperature is increased. say. In this state, some variation in seal strength is included as long as it is clearly differentiated from the rate of change in seal strength in other temperature ranges.

In the present invention, the seal strength after the heat sealing in the first heat-sealed portion is at least 2 N/25 mm width or more and 15 N/25 mm width or less in a temperature range of at least 30 ° C. or more, and the second The seal strength of the heat-sealed portion after heat-sealing may be 25 N/25 mm width or more.
In this invention, the first heat-sealed portion has a predetermined seal strength, and the second heat-sealed portion has a predetermined seal strength or more, so that the functions of the first heat-sealed portion and the second heat-sealed portion in the package are enhanced. Appropriate expression.
Here, if the seal strength at the first heat-sealed portion becomes weaker than 2 N/25 mm width, an external force may act during transportation of the packaging bag containing the contents, and the first heat-sealed portion may unintentionally peel off. be. On the other hand, if the seal strength at the first heat seal portion is higher than 15 N/25 width, the difference from the seal strength at the second heat seal portion becomes small, and there is a possibility that the first heat seal portion cannot be selectively peeled off.
In addition, when the predetermined seal strength at the first heat-sealed portion is expressed in a temperature range of 30 ° C. or less, for example, due to fluctuations in heat-sealing conditions when forming a packaging bag, the first heat-sealed portion may be The predetermined seal strength may not be achieved, and the first heat-sealed portion may peel unintentionally. be. Therefore, it is preferable to set the seal strength of the first heat-sealed portion to 2 N/25 mm width or more and 15/25 mm width or less in a temperature range of at least 30°C or more.
Furthermore, if the seal strength at the second heat-sealed portion becomes weaker than 25 N/25 mm width, for example, when the package containing the contents is cooked or sterilized by heating and the internal pressure increases, the second heat-sealed portion will peel. There is a risk. Therefore, it is preferable to set the sealing strength of the second heat-sealed portion to 25 N/25 mm width or more.

A method for producing a package according to one aspect of the present invention is a method for producing a package by superimposing and partially heat-sealing the laminate of the present invention, wherein the heat-sealing temperature increases. A step of heat-sealing the laminate in the temperature range in the first relationship where the seal strength after sealing is saturated, and a seal after the heat sealing for the heat-sealing temperature in the temperature range higher than the first relationship. and a step of heat-sealing the laminate in the second relationship in which the maximum value of the strength ratio is 1.3 N/25 mm/° C. or more in the temperature range.

In the present invention, when the laminate of the present invention is superimposed and heat-sealed by heating to produce a package, heat-sealing is performed in a temperature range (first temperature range) that is the first relationship, and heat-sealing that exhibits easy peelability is formed, and heat-sealed in the temperature range (second temperature range) of the second relationship, which is higher than the temperature range of the first relationship, to form a heat seal exhibiting tight sealability. By this, for example, different foods are stored in one package, the first heat-sealed part is peeled off and different foods are mixed, then the second heat-sealed part is cut and opened, and the mixed food is taken out. A configuration that facilitates cooking and the like can be easily provided.
Here, the stacking of laminates includes the case where one laminate is folded back and overlapped, and the case where two laminates are overlapped.
Moreover, the step of heat-sealing in the temperature range of the first relationship and the step of heat-sealing in the temperature range of the second relationship may be performed first, or may be performed simultaneously.

The top view which shows the package in one Embodiment of this invention. 4 is a graph showing the relationship between bonding temperature and bonding strength of the base film according to the present invention.

An embodiment of the present invention will be described below with reference to the drawings.
In this embodiment, a bag-like package having two storage spaces is exemplified as the package, but various forms such as a form consisting of a container and a lid can be used, and there are also two storage spaces. It is good also as composition provided with not only in multiple. Items to be packaged include various articles other than food, such as medicines, medical supplies, stationery, and miscellaneous goods. Heat sealing is exemplified as bonding for forming the package from the laminate, but welding by ultrasonic waves, for example, can be used.

[Configuration of package]
As shown in FIG. 1, the packaging body 1 is formed, for example, by a three-sided bag making method, and has a bag shape in which a base film 11 as a laminate is overlaid and the periphery and the like are heat-sealed. The package 1 is formed with a first heat-sealed portion 14 defining a first storage space 12 and a second storage space 13 inside, and a second heat-sealed portion 15 heat-sealed around the base film 11. ing.
The first storage space 12 stores, for example, a seasoning liquid, and the second storage space 13 stores, for example, foodstuffs.
The first heat seal portion 14 exhibits a so-called easy peel property that can be peeled off with a relatively weak force such as internal pressure. , and the seasoning liquid and the food material are mixed. The second heat-sealed portion 15 exhibits a so-called tight-sealing property, which is a relatively strong seal that does not separate due to, for example, internal pressure.
The packaging body 1 has a first inlet 16 into which the seasoning liquid can be introduced and which is sealed by forming a second heat-sealed portion 15 after the seasoning liquid is introduced. and a second input port 17 in which a second heat-sealed portion 15 is formed and sealed.

[Configuration of base film]
The base film 11 has a laminated structure including a base layer and a sealant layer (corresponding to the film of the present invention) laminated on the base layer. Note that the base film 11 is not limited to two layers, and may have a multi-layer structure in which other various intermediate layers, laminate layers, and the like are appropriately laminated.

(Base material layer)
For the base material layer, for example, polyolefin resin, nylon resin, polyethylene terephthalate resin, or the like is used.
Polyolefin resins include polypropylene resins such as homopolypropylene (HPP), random polypropylene (RPP), block polypropylene (BPP), high density polyethylene (HDPE), (linear) low density polyethylene : LDPE), linear ethylene-α-olefin copolymers, and the like are used.
As the nylon resin, nylon 6, nylon 8, nylon 11, nylon 12, nylon 6,6, nylon 6,10, nylon 6,12 and the like can be used.
Moreover, various additives such as a colorant can be appropriately added to the base material layer.

(sealant layer)
The sealant layer is a resin in which at least two polymers with different solubility parameters (Solubility Parameter: δ, hereinafter referred to as sp value) ((cal/cm ³ ) ^1/2 ) and a nucleating agent are blended. It is made of a composition. In this embodiment, two types of component (A) and component (B) are exemplified.
Here, the sp value (δ) is calculated according to the calculation method proposed by Fedors. Specifically, Ev (evaporation energy) and V (molar volume) in the table described in "Polym. Eng. Sci., 14 (2), 147-154 (1974)" are obtained, and the following is calculated based on the formula (1).
δ=(Ev/V) ^1/2 (1)

One of the polymers, specifically the component (A) having the highest melting point, is preferably a polyolefin resin, particularly a polypropylene polymer.
Polypropylene polymers include, for example, homopolypropylene, polypropylene random copolymers, and polypropylene block copolymers. As the component (B), which is another type of polymer to be described later, an ethylene/methacrylic acid copolymer that is suitably used and a third polymer that exhibits appropriate compatibility with polyethylene copolymers and tight sealing properties From the viewpoint of the temperature range for forming the two-heat seal portion 15, the component (A) is particularly preferably a polypropylene random copolymer. Homopolypropylene and polypropylene block copolymers have a melting point of around 160°C. As a result, the temperature at which the second heat-sealing portion 15 develops a tight seal is relatively high, which is effective when dealing with high temperatures depending on the items to be packaged and the application.
In addition, sp value at the time of using a polypropylene random copolymer as a component (A) is 8.0.
The melting point and melt flow rate (230° C., under a load of 2160 g) (JIS K7210) of component (A) are appropriately set according to the intended sealing properties such as the object to be packaged and the application.

The blending amount of component (A) is 5 to 20% by mass, preferably 8 to 20% by mass, particularly preferably 8 to 15% by mass, based on the total amount of the resin composition.
If the amount of the component (A) is less than 5% by mass based on the total amount of the resin composition, the proportion of so-called island structure may decrease, and the easy peel property may not be exhibited. On the other hand, if the blending amount of component (A) is more than 20% by mass based on the total amount of the resin composition, fusion bonding of both components (A) and (B) is inhibited during heat sealing in the second temperature range. This is because there is a risk that the tight sealing property will not be exhibited.
In this way, it is possible to control both the easy peel property and the tight seal property by adjusting the blending amount of the component (A), which is the polymer having the highest melting point.

The polymer of component (B) exhibits an sp value different from that of component (A).
Specifically, the absolute value of the difference in sp value between component (A) and component (B) is preferably 0.7 or more and 1.2 or less.
Here, when |sp(A)−sp(B)| may not be able to form On the other hand, when |sp(A)−sp(B)| Formation of the base film 11 made of the resin composition, for example, may become unstable due to the instability of the dispersed state of the two components. For example, when polypropylene and nylon 12 (SP value = 9.9) are used as the polymer, there is a possibility that the compatibility will be significantly deteriorated and the film formability will become unstable. Therefore, the absolute value of the difference in sp value between component (A) and component (B) is preferably set to 0.7 or more and 1.2 or less. For example, polypropylene (SP value = 7.9) as component (A), and ethylene/methacrylic acid copolymer (SP value = 9.1) or low density polyethylene (SP value = 8.6) as component (B). Even when used, it can clearly provide easy peelability and tight sealability.

In addition, the ratio of the melt flow rate (MFR) (230° C., under a load of 2160 g) (JIS K7210) of the component (A) exhibiting the island structure to the component (B) exhibiting the sea structure was 0.5. It is preferably 1 or more and 1.2 or less. That is, when the MFRs of component (A) and component (B) are MFR(A) and MFR(B), respectively, the relationship between MFR(A) and MFR(B) is 0.1≦|MFR(A )/MFR(B)|≤1.2.
If |MFR(A)÷MFR(B)| On the other hand, if |MFR(A)/MFR(B)| Therefore, it is preferable to set the MFR ratio of the component (A) exhibiting the island structure to the component (B) exhibiting the sea structure to be 0.1 or more and 1.2 or less.

The absolute value of the difference in melting point (MP) between component (A) and component (B) is preferably 35 or more and 70 or less. That is, when the melting points of component (A) and component (B) are MP(A) and MP(B), respectively, the relationship between MP(A) and MP(B) is 35≦|MP(A)− MP(B)|≤70, preferably 38≤|MP(A)-MP(B)|≤70, particularly preferably 40≤|MFR(A)-MFR(B)|≤70.
Here, if |MP(A)−MP(B)| There is On the other hand, when |MP(A)−MP(B)| In this case, the melting point of the polyolefin resin, nylon resin, polyethylene terephthalate resin, etc. used as the base material layer is close to the second temperature range, and the adhesion to the seal bar during heat sealing and the packaging made of the base film 11 This may lead to shrinkage of the second heat-sealed portion 15 of the body 1 . Therefore, the absolute value of the difference in melting point between component (A) and component (B) is preferably set to 35 or more and 70 or less, more preferably 38 or more and 70 or less, and particularly preferably 40 or more and 70 or less. . For example, polypropylene (melting point 135° C. or higher and 160° C. or lower) is used as component (A), and ethylene/methacrylic acid copolymer (melting point 99° C.) or ethylene/vinyl acetate copolymer (melting point 89° C.) is used as component (B). Etc. can clearly provide easy peelability and tight sealability.

The polymer of component (B) can be any resin that satisfies the above conditions.
Specifically, an ethylene/methacrylic acid copolymer, a polyethylene copolymer, or the like is preferably used.

Nucleating agents (component (C)) include, for example, fatty acid metal salts, carboxylic acid metal salts, phosphoric acid ester metal salts, rosin metal salts, talc, mica, sorbitol derivatives and the like. In particular, fatty acid metal salts are suitable as the component (B) from the viewpoint of promoting uniform crystal formation of ethylene/methacrylic acid copolymers and polyethylene copolymers that are suitably used.
The blending amount of component (C) is preferably 1% by mass or more and 3% by mass or less with respect to the total amount of the resin composition.
If the amount of the component (C) is less than 1% by mass based on the total amount of the resin composition, the nucleating action will be insufficient and the crystallization rate after heat sealing will be slowed down, resulting in particularly easy peelability. It may take time to On the other hand, even if the amount of the component (C) is more than 3% by mass based on the total amount of the resin composition, the nucleating action is saturated, and the cost increases as the amount of the nucleating agent added increases. This is because there is a risk of
In this manner, the amount of the nucleating agent (component (C)) blended can be used to control changes in seal properties over time.

The resin composition constituting the sealant layer may optionally contain, for example, a lubricant, an anti-blocking agent, etc., in order to improve workability during film formation of the base film 11 and secondary processing such as the production of the package 1. Additional agents and the like can be added.
The base film 11 can be manufactured by various methods such as the inflation method.

(Method for manufacturing package)
Next, a method for manufacturing the packaging bag will be described.
The method for manufacturing the package 1 is manufactured using, for example, a manufacturing apparatus that performs three-sided bag making, and includes a film feeding step of feeding and overlapping the base film 11, and heat sealing the overlapping base film 11 to perform a first heat sealing portion. 14, and a second heat sealing step of heat-sealing the overlapping substrate films 11 to form the second heat-sealed portion 15, and the like.
In the film delivery step, the base film 11 wound on the take-up roll 62 is pulled out, the sealant layers are superimposed so that they face each other, and the base film 11 is delivered.

In the first heat-sealing step, the overlapping base film 11 is heat-sealed with a seal bar set in a predetermined temperature range (hereinafter referred to as the first temperature range) to form a first heat-sealed portion 14 exhibiting easy peelability. to form In the first temperature range in the first heat sealing step, the component (A) constituting the sealant layer exhibits a so-called island structure, and the component (B) exhibits a so-called sea structure.
In this first temperature range, the component (A) in the crystallized state impedes the fusion by the component (B) in the molten state, exhibiting easy peelability with relatively weak seal strength. In this first temperature range, the seal strength does not fluctuate much, that is, a constant state in which the seal strength is saturated with respect to the temperature. The region where the seal strength saturates with respect to the rise in the heat sealing temperature is defined as the first relationship as shown in FIG. 2, for example. In addition, in the first relationship, the constant state in which the seal strength is saturated may be substantially constant to the extent that it can be differentiated from the following second relationship, as shown in FIG. It is within the permissible range that the value of the seal strength fluctuates within the range of ±3N/25mm.
In this manner, the base film 11 is heat-sealed in the first temperature range of the first relationship in which the sealant layer exhibits the sea-island layer structure, thereby forming the easy-peel first heat-sealed portion 14 .

Here, it is preferable that the seal strength of the first heat-sealed portion 14 exhibits a constant easy peel property in a temperature range of at least 30°C or more. The seal strength is set to 2 N/25 mm width or more and 15 N/25 mm width or less, preferably 2 N/25 mm width or more and 13 N/25 mm width or less, particularly preferably 2 N/25 mm width or more and 10 N/25 mm width or less. That is, the blending of the resin composition of the sealant layer is set so that the seal strength of the first heat seal portion 14 is 2 N/25 mm width or more and 15 N/25 mm width or less. Specifically, the seal strength is adjusted by increasing or decreasing the blending amounts of the components (A) and (B).
If the sealing strength of the first heat-sealed portion 14 is less than 2N/25mm width, the contents stored therein may unintentionally peel off due to external force during transportation of the packaging bag. On the other hand, if the seal strength at the first heat seal portion 14 is stronger than 15 N/25 mm width, the difference from the seal strength at the second heat seal portion 15 becomes small, and the first heat seal portion 14 may not be selectively peeled off. This is because

In the second heat-sealing step, the overlapping base film 11 is heat-sealed with a seal bar set to a temperature range (second temperature range) higher than the first temperature range, thereby forming a second heat-sealing portion 15 exhibiting tight sealability. to form In the second temperature range in the second heat-sealing step, the layer structure is such that the component (A) and the component (B) constituting the sealant layer are in a molten state.
In this second temperature range, due to fusion of both the melted component (A) and component (B), a tight sealing property with relatively high heat strength is exhibited. In this second temperature range, the maximum value of the ratio of the seal strength to the heat seal temperature is defined as a relationship of 1.3 N/25 mm/°C or more as the second relationship. Specifically, for example, as shown in FIG. 2, the relationship between the heat sealing temperature and the seal strength is in direct proportion, and the maximum value of the slope of the direct proportion is 1.3 N / 25 mm / ° C. or more. Define as relationship.
In this way, the base film 11 is heat-sealed in the second temperature range of the second relationship in which both the component (A) and the component (B) melt in the sealant layer, whereby the second heat-sealing of the tight-sealing property is achieved. A portion 15 is formed.

Here, the seal strength of the second heat seal portion 15 is 25 N/25 mm width or more, preferably 30 N/25 mm width or more, and particularly preferably 35 N/25 mm width or more.
When the seal strength of the second heat seal portion 15 is less than 25 N/25 mm width, for example, when the internal pressure increases when the package 1 containing the contents is heated or sterilized, the second heat seal portion 15 is peeled off. This is because there is a risk of

After the first heat-sealing step and the second heat-sealing step, the packaging body 1 is appropriately cut to cut out the package 1 in which the first heat-sealed portion 14 and the second heat-sealed portion 15 are formed.
Then, a predetermined amount of the object to be packaged is put into the obtained package 1 from the first inlet 16 and the second inlet 17 by a filling device (not shown), and the first inlet 16 and the second inlet 17 are filled with A second heat-sealed portion 15 is formed and sealed, and the package is filled.

[Action and effect of the embodiment]
In the above-described embodiment, as the sealant layer of the base film 11 constituting the package 1, a resin composition containing polymers of components (A) and (B) having different sp values and a nucleating agent is used. ing.
Therefore, the desired easy peel property and tight seal property can be exhibited immediately after heat sealing. Therefore, for example, it is possible to easily determine the difference in the heat-sealed state of the package 1, that is, to easily evaluate the sealing characteristics of the first heat-sealed portion 14 and the second heat-sealed portion 15 in a short time, and to easily perform quality control. .
Furthermore, from the relationship between the temperature at which the base film 11 is heat-sealed and the layer structure of the sealant layer, the first relationship in the first temperature range and the second relationship in the second temperature range can be clearly differentiated. The easy-peel first heat-sealed portion 14 formed by sealing and the tight-sealed second heat-sealed portion 15 can be easily formed only by setting the heat-sealing temperature.

In the above embodiment, the absolute value of the difference in sp value between the components (A) and (B) is 0.7 or more and 1.2 or less as the resin composition constituting the sealant layer.
For this reason, the components (A) and (B) can be properly dispersed when the first heat-sealed portion 14 and the second heat-sealed portion 15 exhibit the desired sealing properties.

Further, in the above embodiment, as the resin composition constituting the sealant layer, the ratio of MFR of the component (A) showing the island structure to the component (B) showing the sea structure is 0.1 or more and 1.2 or less. and
For this reason, the components (A) and (B) can be properly dispersed when the first heat-sealed portion 14 and the second heat-sealed portion 15 exhibit the desired sealing properties.

Furthermore, in the above embodiment, the absolute value of the difference in the melting point between the components (A) and (B) is 35 or more and 70 or less as the resin composition constituting the sealant layer.
Therefore, depending on the temperature relationship between the first temperature range and the melting point, for example, heat sealing can be easily performed.

Further, in the above embodiment, the resin composition constituting the sealant layer contains the component (A) and the nucleating agent in predetermined compounding amounts.
Therefore, the easy-peel first heat-sealed portion 14 and the tight-sealed second heat-sealed portion 15 formed by heat-sealing can be formed more easily, and the sealing characteristics can be stabilized immediately after heat-sealing. can be expressed as

In the above-described embodiment, by using a fatty acid metal salt as a nucleating agent, crystallization is promoted by the nucleating action, and the desired sealing properties can be exhibited immediately after heat sealing.
In particular, when a polypropylene polymer is used as the component (A) and an ethylene/methacrylic acid copolymer is used as the component (B), the desired sealing properties can be exhibited satisfactorily due to the excellent nucleating action.

Further, in the above embodiment, the seal strength of the first heat seal portion 14 is set to 2 N/25 mm width or more and 15 N/25 mm width or less, and the seal strength of the second heat seal portion 15 is set to 25 N/25 mm width or more. there is
Therefore, in the first heat-sealed portion 14, unintentional peeling can be prevented, and the first heat-sealed portion 14 can be selectively peeled. Moreover, in the second heat seal part 15, it can prevent that the second heat seal part 15 peels by internal pressure, for example.

[Modification]
Although the best configuration for carrying out the present invention has been disclosed in the above description, the present invention is not limited to this. Thus, although the present invention has been described primarily in terms of particular embodiments, it should be understood that materials, quantities, and other details could be added to the above-described embodiments without departing from the spirit and scope of the invention. Various modifications can be made by those skilled in the art.
Therefore, the descriptions that limit the materials, layer configurations, etc. disclosed above are exemplified to facilitate understanding of the present invention, and do not limit the present invention. Descriptions by names that exclude some or all of the limitations are included in the present invention.

For example, the bag-making method for manufacturing the package 1 is not limited to three-sided bag-making, and various methods such as a rotary drum method and a pillow method can be used. Moreover, the package body may be configured to include an engaging member such as a zipper tape so that it can be resealed after the package is put in and taken out.
Also, the base film 11 can be manufactured by the inflation method, or various methods such as the calendering method can be applied. Further, not limited to co-extrusion, for example, a film corresponding to the sealant layer and a film corresponding to the substrate layer may be attached and laminated.

The base film 11 is not limited to a laminated structure in which a base layer and a sealant layer are laminated, and may be a single-layer film formed of the resin composition of the present invention.
Further, the composition of the raw materials of the resin composition, the compounding amount, the sp value of the components (A) and (B), the melt flow rate, the melting point, etc. are not limited to the above embodiment, and can be set as appropriate.

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The film configuration, raw materials, preparation of test pieces, and measurement of bonding strength by heat sealing in each example were carried out by the following methods.

[Examples 1 and 2, Comparative Examples 1 and 2]
A three-layer film having a sealant layer with a thickness of 12.5 μm, an intermediate layer with a thickness of 25 μm, and a laminate layer with a thickness of 12.5 μm was produced by inflation molding using the raw materials below.

<raw materials>
(sealant layer)
Component (A): Propylene-ethylene copolymer (sp value: 7.9, MFR (230°C, under 2160g load): 1.3g/10 min, density: 0.930g/cm ³ , melting point: 142°C)
Component (B): Ethylene/methacrylic acid copolymer (sp value: 9.1, MFR (190°C, under 2160 g load): 3.0 g/10 minutes, density: 0.930 g/cm ³ )
Component (C): Nucleating agent for polyolefin (manufactured by Riken Vitamin Co., Ltd., trade name: CN-002)

(middle layer)
Linear low density polyethylene (MFR (190° C., under 2160 g load): 2.5 g/10 min, density: 0.935 g/cm ³ ) 62% by mass, low density polyethylene (MFR (190° C., under 2160 g load): 2.0 g/10 minutes, density 0.922 g/cm ³ ) 38% by mass

(Laminate layer)
Linear low-density polyethylene (MFR (190° C., under 2160 g load): 2.5 g/10 minutes, density: 0.935 g/cm ³ ) 100.00% by mass

<Preparation of test piece for bonding strength measurement>
According to the formulation shown in Table 1 below, a film having a three-layer structure was produced by inflation molding.
The sealant layers of the obtained film were heat-sealed at each temperature using a thermal gradient tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., trade name: HG-100-2) to prepare test pieces.

<Seal strength>
Using a tensile tester manufactured by Shimadzu Corporation (trade name: AGS-X), according to the test method for T-peel peeling of JIS K6854, the test piece of each example was left to stand immediately after heat sealing and for one day after heat sealing. Afterwards, the seal strength was measured. The seal strength was measured by subjecting the test piece of each example to T-peel at a tensile speed of 200 mm/min in MD.
The results are shown in Table 2 below and FIG.

<Evaluation results>
As is clear from the measurement results shown in Table 2 and FIG. 2, in Comparative Example 1, which does not contain the nucleating agent of component (C), the seal strength immediately after heat sealing and after standing for one day after heat sealing Regarding the seal strength, the shapes of the graphs of the first relationship and the second relationship were significantly different. Thus, in Comparative Example 1, it was recognized that the temperature at the boundary between the first relationship and the second relationship fluctuated greatly.
On the other hand, in Examples 1 and 2 containing the nucleating agent of component (C), the difference in the graph shape between the first relationship and the second relationship was small, the change in seal strength over time was small, and the seal characteristics were improved. It was confirmed that it can be expressed after heat sealing.

1 …… package 11 …… base film (film, laminate)
14 …… First heat seal part 15 …… Second heat seal part

Claims (8)

Component (A): 5% by mass or more and 20% by mass or less of a polypropylene polymer relative to the total amount of the composition;
Component (B): a polymer whose solubility parameter (δ, hereinafter referred to as sp value) ((cal/cm ³ ) ^1/2 ) is different from that of component (A);
Component (C): a nucleating agent of 1% by mass or more and less than 3% by mass with respect to the total amount of the composition;
is blended ,
The polymer of component (B) is at least one of an ethylene-methacrylic acid copolymer and a low-density polyethylene copolymer,
The absolute value of the difference in sp value between the component (A) polypropylene polymer and the component (B) polymer is 0.7 or more and 1.2 or less,
Regarding the melt flow rate of the component (A) and the component (B) (230° C., under a load of 2160 g) (JIS K7210), the melt flow rate of the polymer of the component (B) showing a sea structure is different from that of the island structure. The resin composition , wherein the ratio of the melt flow rate of the polypropylene polymer of component (A) is 0.1 or more and 1.2 or less . In the resin composition according to claim 1,
The resin composition, wherein the polypropylene polymer of component (A) is a polypropylene random copolymer. In the resin composition according to claim 1 or claim 2 ,
The absolute value of the difference in melting point between the component (A) polypropylene polymer and the component (B) polymer is 35 or more and 70 or less. A film comprising the resin composition according to any one of claims 1 to 3 as a raw material. a substrate layer;
A film according to claim 4 laminated to the substrate layer;
A laminate comprising: A package formed by superimposing the laminate according to claim 5 and partially heat-sealing it,
A first heat-sealed portion formed by heat-sealing the laminate within the temperature range in the first relationship in which the seal strength after heat-sealing is saturated with respect to the increase in the heat-sealing temperature;
In the second relationship in which the maximum value of the ratio of the seal strength after heat sealing to the heat sealing temperature is 1.3 N / 25 mm / ° C. or more in the temperature range higher than the first relationship, in the temperature range a second heat-sealed portion formed by heat-sealing the laminate;
A package comprising: In the package according to claim 6 ,
The seal strength after the heat sealing in the first heat-sealed portion is at least 2 N/25 mm width or more and 15 N/25 mm width or less in a temperature range of at least 30 ° C. or more,
A package, wherein the seal strength of the second heat-sealed portion after the heat-sealing is 25 N/25 mm width or more. A manufacturing method for manufacturing a package by superimposing the laminate according to claim 5 and partially heat-sealing it,
a step of heat-sealing the laminate within the temperature range in the first relationship in which the seal strength after heat-sealing is saturated with respect to the increase in the heat-sealing temperature;
In the second relationship in which the maximum value of the ratio of the seal strength after heat sealing to the heat sealing temperature is 1.3 N / 25 mm / ° C. or more in the temperature range higher than the first relationship, in the temperature range and a step of heat-sealing the laminate.

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