JP7352153B2 - Manufacturing method of heat seal film - Google Patents

Description

The present disclosure relates to a method of manufacturing a heat seal film.

A film having heat-sealing properties usually includes a base material and a heat-sealable layer (a layer containing a heat-sealing agent; the same applies hereinafter) on the outermost surface of at least one side of the base material. have Applications of films with heat sealability include, for example, packaging and attachment to various members (eg, metals and resins).

By bonding together film-like molded products of different materials such as plastic, paper, and metal foil, we have supplemented properties (e.g., strength, gas barrier properties, moisture resistance, heat sealability, and appearance) that cannot be possessed alone. It is common practice to produce laminated films. Examples of methods for producing the above laminated film include dry lamination, wet lamination, hot lamination, and extrusion lamination. Extrusion lamination is widely used as a method for forming a heat seal layer on a base material because it is advantageous in terms of cost.

In the extrusion lamination method, the heat-sealable resin is melt-extruded onto the base material, and then the resulting laminate is passed between a cooling roll and a nip roll to adhere the heat-sealable resin onto the base material. This is a construction method (for example, see Non-Patent Document 1). In the construction method described above, since the adhesion between the base material and the heat-sealable resin is low, it is necessary to heat and press the laminate by passing it between a heating roll and a nip roll, or to heat and age it (e.g. , see Patent Document 1).

Patent No. 4100484

"Latest Lamination Processing Handbook", published by Processing Technology Research Group, June 30, 1989

However, since the steps of conventional construction methods (for example, Patent Document 1 and Non-Patent Document 1) are complicated, a simpler construction method is desired. Furthermore, there is a need for a construction method that requires fewer steps than conventional construction methods and has excellent adhesion between the base material and the heat seal layer.

The present disclosure has been made in view of the above circumstances.
An object of one embodiment of the present disclosure is to provide a method for producing a heat seal film that can produce a heat seal film with excellent adhesion between a base material and a heat seal layer using a simple process.

The present disclosure includes the following aspects.
<1> The method includes a step of melt-extruding a heat sealing agent containing a resin, and a step of thermocompression bonding the heat sealing agent and a resin base film using a first compression bonding member. When the melting point of the resin contained in is Tm, the temperature of the first pressure bonding member is Tm - 20°C to Tm + 50°C, and the heat sealing agent and the resin are melted and extruded. A method for producing a heat-sealing film, wherein the temperature of the heat-sealing agent is Tm-20° C. or higher until thermocompression bonding with the base film starts.
<2> The heat seal film according to <1>, wherein the time from melt extrusion of the heat seal agent to the start of thermocompression bonding between the heat seal agent and the resin base film is 30 seconds or less. manufacturing method.
<3> The method for producing a heat seal film according to <1> or <2>, wherein the temperature of the first pressure bonding member is Tm-10°C to Tm+30°C.
<4> In the thermocompression bonding step, the heat sealing agent and the resin base film are sandwiched between the first compression bonding member and a second compression bonding member facing the first compression bonding member. The method for producing a heat seal film according to any one of <1> to <3>, wherein the heat seal agent and the resin base film are bonded by thermocompression.
<5> The method for producing a heat seal film according to <4>, wherein the second pressure bonding member is a roll.
<6> In the thermocompression bonding step, the heat sealant and the resin base film are thermocompression bonded by bringing the first compression bonding member and the heat sealant into contact <1> to <5> The method for producing a heat seal film according to any one of the above.
<7> The method for producing a heat seal film according to <6>, wherein the contact time between the first pressure bonding member and the heat sealing agent is 1 second or more.
<8> The method for producing a heat seal film according to any one of <1> to <7>, wherein the first pressure bonding member is a roll.
<9> The method for producing a heat seal film according to any one of <1> to <8>, wherein the resin contained in the heat seal agent has a melting point Tm of 80° C. to 150° C.
<10> The resin contained in the heat sealing agent is a polyolefin having at least one functional group selected from the group consisting of a carboxy group, a group having a carboxylic acid anhydride structure, and a hydroxy group. <1> ~The method for producing a heat seal film according to any one of <9>.
<11> The method for producing a heat seal film according to any one of <1> to <10>, wherein the resin base film is a polyester film.
<12> In the thermocompression bonding step, the heat sealant and the resin base film are thermocompression bonded via an easily adhesive layer disposed between the heat sealant and the resin base film.<1 >>The method for producing a heat seal film according to any one of <11>.

According to one aspect of the present disclosure, it is possible to provide a method for producing a heat-seal film that can produce a heat-seal film with excellent adhesion between a base material and a heat-seal layer through simple steps.

FIG. 1 is a schematic diagram showing an example of a method for manufacturing a heat seal film according to the present disclosure. FIG. 1 is a schematic diagram showing an example of a method for manufacturing a heat seal film according to the present disclosure.

Embodiments of the present disclosure will be described below. The present disclosure is not limited to the following embodiments, and can be implemented with appropriate changes within the scope of the purpose of the present disclosure.

In the present disclosure, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as lower and upper limits. In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.
In this disclosure, the term "process" includes not only an independent process but also a process that is not clearly distinguishable from other processes, as long as the intended purpose of the process is achieved. .
In the present disclosure, if there are multiple substances corresponding to each component in the composition, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. .
In the present disclosure, "mass %" and "weight %" have the same meaning, and "mass parts" and "weight parts" have the same meaning.
In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present disclosure, "Tm" means the melting point (° C.) of the resin contained in the heat sealing agent, unless otherwise specified.

<Method for manufacturing heat seal film>
A method for producing a heat-sealing film according to the present disclosure includes a step of melt-extruding a heat-sealing agent containing a resin (hereinafter sometimes referred to as a "melt-extrusion step"), and a step of melt-extruding a heat-sealing agent containing a resin. A process of thermocompression bonding a sealant and a resin base film (hereinafter sometimes referred to as a "thermocompression bonding process"), and when the melting point of the resin contained in the heat sealant is Tm, The temperature of the first pressure bonding member is Tm-20°C to Tm+50°C, and the temperature from the time the heat sealant is melted and extruded until the thermocompression bonding between the heat sealant and the resin base film is started. The temperature of the heat sealing agent during this period is Tm-20°C or higher. The method for producing a heat-sealing film according to the present disclosure includes the steps described above, so that a heat-sealing film with excellent adhesion between the base material and the heat-sealing layer can be produced in a simple process.

The reason why the method for producing a heat-sealing film according to the present disclosure achieves the above effects is presumed to be as follows. In a conventional method for producing a heat-sealing film, a heat-sealing agent melt-extruded onto a resin base film is usually solidified by cooling, and then the resin base film and the heat-sealing agent are bonded by thermocompression. On the other hand, the method for producing a heat-sealing film according to the present disclosure includes the step of thermocompression bonding the heat-sealing agent and the resin base film using a first pressure bonding member whose temperature is Tm-20°C to Tm+50°C. Furthermore, since the temperature of the heat sealing agent is Tm-20°C or higher after the heat sealing agent is melt-extruded and before the thermocompression bonding between the heat sealing agent and the resin base film is started, the heat sealing agent is not heated. It is possible to increase the adhesion between the base material and the heat seal layer while reducing the number of steps required from melt extrusion of the sealant to thermocompression bonding to the resin base film. Therefore, according to the method for producing a heat-sealable film according to the present disclosure, a heat-sealable film with excellent adhesion between the base material and the heat-sealable layer can be produced through a simple process.

Each step of the method for producing a heat seal film according to the present disclosure will be described below.

<<Melt extrusion process>>
The method for producing a heat seal film according to the present disclosure includes a step of melt extruding a heat seal agent containing a resin (melt extrusion step).

In the melt-extrusion step, it is preferable to melt-extrude the heat-sealing agent and bring the heat-sealing agent into contact with the resin base film. In the melt extrusion step, it is more preferable to melt-extrude the heat sealing agent and bring the heat sealing agent into contact with the resin base film while conveying the resin base film.

The method for melt-extruding the heat sealant is not limited, and any known method can be used. For example, a known extruder may be used to extrude the melt-kneaded heat sealing agent through a T-die. Examples of the extruder include a single screw extruder and a multi-screw extruder.

The heating temperature when melting and kneading the heat sealing agent is not limited, and may be determined depending on the melting point (Tm) of the resin contained in the heat sealing agent. The heating temperature can be determined, for example, in the range of 120°C to 250°C.

In the method for producing a heat-sealing film according to the present disclosure, the period from when the heat-sealing agent is melt-extruded until the start of thermocompression bonding between the heat-sealing agent and the resin base film (hereinafter referred to as "transition period before thermocompression bonding") ”) The temperature of the heat sealing agent is Tm-20°C or higher. By setting the temperature of the heat sealant during the transition period before thermocompression bonding to Tm - 20°C or higher, the heat sealant and the resin base film can be thermocompression bonded before the heat sealant completely solidifies. A heat-sealing film with excellent adhesion between the base material and the heat-sealing layer can be produced through a simple process. The temperature of the heat sealing agent during the transition period before thermocompression bonding is preferably Tm-20°C or higher, more preferably Tm-10°C or higher. There is no upper limit to the temperature of the heat sealant during the transition period before thermocompression bonding. The temperature of the heat sealing agent during the transition period before thermocompression bonding is, for example, preferably Tm+100°C or lower, more preferably Tm+90°C or lower.

The time from melt extrusion of the heat sealant to the start of thermocompression bonding between the heat sealant and the resin base film (hereinafter sometimes referred to as "transition time before thermocompression bonding") is 30 seconds or less. The time is preferably 10 seconds or less, more preferably 5 seconds or less, and particularly preferably 1 second or less. By setting the transition time before thermocompression bonding to 30 seconds or less, it is possible to produce a heat seal film with excellent adhesion between the base material and the heat seal layer through a simple process. In addition, by setting the transition time before thermocompression bonding to 30 seconds or less, the heat sealant can be transferred between the time the heat sealant is melted and extruded until the thermocompression bonding between the heat sealant and the resin base film starts. It becomes easier to maintain the temperature at Tm-20°C or higher.

[Heat sealing agent]
In the present disclosure, the term "heat sealing agent" refers to a compound having heat fusibility or a composition having heat fusibility.

Examples of the resin (hereinafter sometimes simply referred to as "resin") contained in the heat sealing agent include polyolefin, polyester, polyurethane, polyamide, ethylene vinyl acetate, and synthetic rubber. From the viewpoints of heat resistance, chemical resistance, and long-term durability, the resin contained in the heat sealing agent is preferably polyolefin, and more preferably polyethylene or polypropylene.

The polyolefin is not limited as long as it is a polymer having a structural unit derived from an olefin, and any known polyolefin can be used. The polyolefin may be a homopolymer of olefins, a copolymer of two or more types of olefins, or a copolymer of an olefin and a monomer other than olefins.

Examples of polyolefins include homopolymers of olefins having 2 to 8 carbon atoms, copolymers of olefins having 2 to 8 carbon atoms, and copolymers of olefins having 2 to 8 carbon atoms and other monomers. Can be mentioned. Specific polyolefins include, for example, polyethylene, polypropylene, polyisobutylene, poly(1-butene), poly4-methylpentene, polyvinylcyclohexane, polystyrene, poly(p-methylstyrene), poly(α-methylstyrene), Examples include α-olefin copolymers, ethylene/vinyl acetate copolymers, ethylene/acrylic acid copolymers, ethylene/methyl methacrylate copolymers, ethylene/vinyl acetate/methyl methacrylate copolymers, and ionomer resins. The polyolefin may be a chlorinated polyolefin obtained by chlorinating the above polyolefin.

Examples of polyethylene include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene.

Examples of the α-olefin copolymer include ethylene/propylene block copolymer, ethylene/propylene random copolymer, ethylene/1-butene copolymer, ethylene/4-methyl-1-pentene copolymer, and Examples include ethylene/hexene copolymers.

The polyolefin preferably has a functional group from the viewpoint of adhesion to an adherend (eg, metal). Examples of the functional group include a carboxy group, a group having a carboxylic acid anhydride structure, and a hydroxy group (hereinafter sometimes referred to as "hydroxyl group"). Examples of the group having a carboxylic anhydride structure include a group having a maleic anhydride structure and a group having a phthalic anhydride structure.

The functional group contained in the polyolefin is at least one functional group selected from the group consisting of a carboxy group, a group having a carboxylic acid anhydride structure, and a hydroxy group, from the viewpoint of adhesion to an adherend (for example, metal). It is preferably a group, and more preferably at least one functional group selected from the group consisting of a carboxy group and a group having a carboxylic anhydride structure, and a carboxy group and a group having a maleic anhydride structure. Particularly preferred is at least one functional group selected from the group consisting of:

The polyolefin is also preferably a polyolefin into which a functional group has been introduced (hereinafter sometimes referred to as "modified polyolefin") from the viewpoint of adhesion to an adherend (for example, metal). The modified polyolefin is preferably modified polypropylene. Examples of the functional groups contained in the modified polyolefin include the above-mentioned functional groups.

The modified polyolefin must have at least one functional group selected from the group consisting of a carboxy group, a group having a carboxylic acid anhydride structure, and a hydroxy group, from the viewpoint of adhesion to an adherend (e.g., metal). is preferable, and it is more preferable to have at least one functional group selected from the group consisting of a carboxy group and a group having a carboxylic anhydride structure, and more preferably from the group consisting of a carboxy group and a group having a maleic anhydride structure. It is particularly preferred to have at least one selected functional group.

Modified polyolefins are modified polyolefins having an acid value of 0.5 mgKOH/g to 200 mgKOH/g (hereinafter referred to as "acid-modified polyolefins") from the viewpoint of adhesion to adherends (e.g. metals) and resistance to electrolytes. ), and at least one modified polyolefin selected from the group consisting of modified polyolefins having a hydroxyl value of 0.5 mgKOH/g to 200 mgKOH/g (hereinafter sometimes referred to as "hydroxyl modified polyolefin"). It is preferably a modified polyolefin having an acid value of 0.5 mgKOH/g to 200 mgKOH/g.

The acid value indicates the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the sample, and is measured according to "JIS K 0070:1992". Specifically, a precisely weighed sample is dissolved in a mixed solvent having a mass ratio of mixed xylene:n-butanol=1:1 to obtain a sample solution. Next, a few drops of 1% by mass/volume phenolphthalein ethanol solution was added to this sample solution as an indicator, and titration was performed using 0.1 mol/L ethyl alcohol solution of potassium hydroxide as a titrant. Calculate the acid value according to the formula. In the formula below, T represents the titration amount (mL), F represents the factor of the titrant, and W represents the sample collection amount (g).

Formula: Acid value = (T x F x 56.11 x 0.1)/W

The hydroxyl value is measured according to "JIS K 0070:1992".

The acid-modified polyolefin preferably has at least one functional group selected from the group consisting of a carboxy group and a group having a carboxylic acid anhydride structure, and preferably has at least one functional group selected from the group consisting of a carboxy group and a group having a maleic anhydride structure. It is particularly preferable to have at least one functional group selected from the following.

The acid value is preferably 0.5 mgKOH/g to 200 mgKOH/g, and 0.5 mgKOH/g to 100 mgKOH/g, from the viewpoint of adhesion to adherends (for example, metals) and resistance to electrolytes. It is more preferably 0.5 mgKOH/g to 50 mgKOH/g.

Examples of acid-modified polyolefins include maleic anhydride-modified polypropylene, ethylene-(meth)acrylic acid copolymer, ethylene-acrylic ester-maleic anhydride ternary copolymer, and ethylene-methacrylic ester-maleic anhydride. Examples include terpolymers.

Acid-modified polyolefins can be produced, for example, by graft-modifying or copolymerizing polyolefins using at least one polymerizable ethylenically unsaturated carboxylic acid or a derivative thereof. Examples of the polyolefin to be modified include the polyolefins described above. Preferred examples of polyolefins to be modified include propylene homopolymers, propylene and α-olefin copolymers, ethylene homopolymers, and ethylene and α-olefin copolymers.

Examples of acid-modified polyolefins include "Modic" (registered trademark) manufactured by Mitsubishi Chemical Corporation, "Admer" (registered trademark) manufactured by Mitsui Chemicals, "Unistol" (registered trademark) manufactured by Mitsui Chemicals, and Toyo Kasei Corporation. "Toyotac" (registered trademark) manufactured by the company, "Umex" (registered trademark) manufactured by Sanyo Chemical Industries, Ltd., "Lexpar EAA" manufactured by Japan Polyethylene Co., Ltd., "Lexpar ET" manufactured by Japan Polyethylene Co., Ltd., Dow Chemical It is available as "Primacol" manufactured by Mitsui-Dow Polychemicals Co., Ltd., "Nucrel" manufactured by Mitsui-Dow Polychemicals Co., Ltd., and "Bondine" (registered trademark) manufactured by Arkema.

A hydroxyl group-modified polyolefin is a polyolefin that has a hydroxyl group in its molecule.

The hydroxyl value is preferably 1 mgKOH/g to 100 mgKOH/g, more preferably 1 mgKOH/g to 80 mgKOH/g, from the viewpoint of adhesion to adherends (for example, metals) and resistance to electrolytes. , 1 mgKOH/g to 70 mgKOH/g is particularly preferred.

Hydroxyl group-modified polyolefins can be synthesized, for example, by graft modification or copolymerization of polyolefins using hydroxyl group-containing (meth)acrylic acid esters or hydroxyl group-containing vinyl ethers.

Examples of hydroxyl group-containing (meth)acrylic esters include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycerol (meth)acrylate, lactone-modified hydroxyethyl (meth)acrylate, and (meth)acrylate. Examples include polyethylene glycol acid and polypropylene glycol (meth)acrylate.

Examples of the hydroxyl group-containing vinyl ether include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether.

The melting point (Tm) of the resin is not limited. From the viewpoint of heat resistance and long-term durability, the melting point (Tm) of the resin is preferably 80°C or higher, more preferably 90°C or higher, and particularly preferably 120°C or higher. From the viewpoint of processability, the melting point (Tm) of the resin is preferably 200°C or lower, more preferably 180°C or lower, and particularly preferably 160°C or lower. The melting point (Tm) of the resin is measured according to the method described in the Examples.

The molecular weight of the resin is not limited. From the viewpoint of processability and long-term durability, the molecular weight of the resin is preferably 100,000 or more, more preferably 150,000 or more, and particularly preferably 20 or more. From the viewpoint of processability and long-term durability, the molecular weight of the resin is preferably 500,000 or less, more preferably 450,000 or less, and particularly preferably 400,000 or less. The molecular weight of the resin is the weight average molecular weight measured by gel permeation chromatography (GPC) in terms of simple polystyrene.

The measurement conditions for gel permeation chromatography are shown below.
(1) Column: TSKgel GMH6-HT (2 columns, Tosoh Corporation), and TSKgel GMH6-HTL (2 columns, Tosoh Corporation)
(2) Eluent: o-dichlorobenzene (containing 0.025% by mass BHT (dibutylhydroxytoluene))
(3) Sample concentration: 0.1mg/mL
(4) Flow rate: 1mL/min (5) Measurement temperature: 140℃
(6) Standard material: Polystyrene (7) Detector: Differential refractometer

The heat sealing agent may contain one type of resin alone, or may contain two or more types of resin.

The content of the resin in the heat-sealing agent is preferably 90% by mass or more, and preferably 95% by mass or more, based on the total mass of the heat-sealing agent, from the viewpoint of improving adhesiveness to the adherend. It is more preferable, and particularly preferably 98% by mass or more.

The upper limit of the resin content in the heat sealing agent is not limited. The content of the resin in the heat sealing agent may be determined, for example, within a range of 100% by mass or less.

The heat sealing agent may contain other components in addition to the resin described above without departing from the spirit of the present disclosure. Other components include, for example, antioxidants, pigments, and fillers. The heat sealing agent may contain one kind of other component alone, or may contain two or more kinds of other components.

[Resin base film]
(resin component)
The resin constituting the resin base film is not limited. The resin constituting the resin base film can be selected depending on, for example, the characteristics required of the base material in the intended use.

The glass transition temperature (Tg) of the resin constituting the resin base film is preferably 70°C or higher, more preferably 75°C or higher, and particularly preferably 100°C or higher. When the glass transition temperature of the resin constituting the resin base film is 70° C. or higher, it is possible to improve the adhesion between the heat seal layer and the resin base film in a moist heat environment. The upper limit of the glass transition temperature of the resin constituting the resin base film is not limited. The glass transition temperature of the resin constituting the resin base film may be determined, for example, in a range of 400° C. or lower.

Glass transition temperature is measured by the following method. 10 mg of the sample is sealed in an aluminum pan for measurement. The aluminum pan was attached to a differential scanning calorimeter (Q100 DSC manufactured by TA Instruments). After raising the temperature from 25°C to 300°C at a rate of 20°C/min and holding it at 300°C for 5 minutes, the aluminum pan is taken out and cooled on a metal plate to rapidly cool it. The aluminum pan is again mounted on the differential scanning calorimeter, and the temperature is raised from 25° C. at a rate of 20° C./min to measure the glass transition temperature. Note that the glass transition temperature is the extrapolation start temperature.

The resin constituting the resin base film is preferably a thermoplastic resin, more preferably polyester, and particularly preferably polyethylene naphthalate.

The polyethylene naphthalate is preferably polyethylene-2,6-naphthalate or polyethylene-2,7-naphthalate, and more preferably polyethylene-2,6-naphthalate.

The number of structural units containing ester bonds in the polyester may be one type alone, or two or more types may be used. That is, the polyester is not limited to a copolymer of one type of polyhydric carboxylic acid and one type of polyhydric alcohol, but may be a copolymer formed from three or more types of monomers. Examples of copolymer components in a copolymer formed from three or more types of monomers include dicarboxylic acids, oxycarboxylic acids, and dihydric alcohols.

Examples of dicarboxylic acids include oxalic acid, adipic acid, phthalic acid, sebacic acid, dodecanecarboxylic acid, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and phenylindanedicarboxylic acid. , 2,6-naphthalene dicarboxylic acid (when the main polymer is not polyethylene-2,6-naphthalate), 2,7-naphthalene dicarboxylic acid (when the main polymer is not polyethylene-2,7-naphthalate), tetralin dicarboxylic acid, decalin dicarboxylic acids, and diphenyl ether dicarboxylic acids.

Examples of oxycarboxylic acids include p-oxybenzoic acid and p-oxyethoxybenzoic acid.

Examples of dihydric alcohols include propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexane methylene glycol, neopentyl glycol, ethylene oxide adduct of bisphenol sulfone, ethylene oxide adduct of bisphenol A, diethylene glycol, and Examples include polyethylene oxide glycol.

Each of the above-mentioned compounds may be used alone or in combination of two or more.

In the copolymerization components of the polyester described above, the acid components include isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and p-oxybenzoic acid. Preferably, it is at least one compound selected from the group consisting of acids. The glycol component is preferably at least one compound selected from the group consisting of trimethylene glycol, hexamethylene glycol neopentyl glycol, and ethylene oxide adducts of bisphenol sulfone.

Among the above, the polyester is preferably a polyester mainly composed of polyethylene-2,6-naphthalate from the viewpoint of mechanical properties and heat and humidity resistance. Here, "mainly composed of polyethylene-2,6-naphthalate" means that the content of ethylene-2,6-naphthalate units is 90 mol% or more (preferably 95 mol% or more) with respect to all the constituent units of the polyester. It means that. There is no upper limit to the content of ethylene-2,6-naphthalate units. The content of ethylene-2,6-naphthalate units based on all the constituent units of the polyester may be determined, for example, within a range of 100 mol% or less.

The resin base film is preferably a polyester film, more preferably a polyethylene naphthalate film, from the viewpoints of mechanical properties and heat and humidity resistance. "Polyester film" means a film containing polyester in an amount of 90% by mass or more (preferably 95% by mass or more) based on the total mass of the film. "Polyethylene naphthalate film" means a film containing polyethylene naphthalate in an amount of 90% by mass or more (preferably 95% by mass or more) based on the total mass of the film. The upper limit of the content of each component described above is not limited. The content of each of the above components may be determined within a range of 100% by mass or less.

(Additive)
The resin base film may contain a filler as necessary from the viewpoint of improving slipperiness, etc., as long as it does not impede the purpose of the present disclosure. As the filler, those conventionally known as agents for imparting slipperiness to films such as polyester films can be used. Examples of fillers include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin. Examples include particles.

The resin base film may contain additives such as colorants, antistatic agents, antioxidants, organic lubricants, and catalysts.

(thickness)
The thickness of the resin base film is not limited. The average thickness of the resin base film is preferably 20 μm to 300 μm from the viewpoint of strength.

The thickness of the resin base film is measured by the following method. In the heat seal film, triangular samples are cut out from 5 locations at 100 mm intervals in the width direction and from 5 locations at 500 mm intervals in the longitudinal direction from the above 5 locations. After each sample is fixed in an embedding capsule, it is embedded in an epoxy resin. The embedded sample is cut in the longitudinal direction (thickness direction) using a microtome (ULTRACUT-S) to prepare thin film sections. Observe and photograph thin film sections using an optical microscope. The thickness of the resin base film is measured from the obtained photograph. The thickness of the resin base film is the arithmetic average of the thicknesses at three locations. The value obtained by arithmetic averaging the measured values obtained from each photograph is defined as the average thickness of the resin base film.

(other layers)
The resin base film may have an easily adhesive layer on at least one surface. When the resin base film has an easily adhesive layer, it is possible to improve the adhesion between the heat sealing agent and the resin base film.

It is preferable that the easily adhesive layer contains a binder resin. The binder resin may be a homopolymer, a copolymer, or a mixture of two or more polymers (polymer blend). Moreover, the binder resin may be crosslinked with a crosslinking agent. Examples of the binder resin include thermoplastic resins and thermosetting resins. Specific examples of the binder resin include polyester, polyimide, polyamide, polyester amide, polyvinyl chloride, poly(meth)acrylate, polyurethane, polyvinyl chloride, polystyrene, and polyolefin. Among the above, the binder resin is preferably polyester, polyimide, poly(meth)acrylate, or polyurethane.

The easily adhesive layer may contain one type of binder resin alone, or may contain two or more types of binder resins.

The content of the binder resin is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the easily adhesive layer. The upper limit of the binder resin content is not limited. The content of the binder resin may be determined, for example, within a range of 100% by mass or less based on the total mass of the easily adhesive layer.

The thickness of the easy-adhesive layer is preferably 5 nm to 200 nm, more preferably 10 nm to 100 nm, and 20 nm to 100 nm from the viewpoint of improving the adhesion between the heat sealant and the resin base film. It is particularly preferable. The thickness of the easily adhesive layer is measured by a method similar to the method for measuring the thickness of the resin base film.

Examples of methods for forming the easily adhesive layer include a laminating method and a coating method. The coating method may be extrusion resin coating or melt resin coating.

The method of forming the easily adhesive layer is preferably a method using a coating liquid. For example, an easily adhesive layer can be formed by applying a coating liquid to a resin base film.

The coating liquid can be prepared, for example, by mixing the binder resin and a solvent. Examples of the solvent include organic solvents and water. Organic solvents include toluene, ethyl acetate, and methyl ethyl ketone.

The coating liquid may contain one type of solvent alone, or may contain two or more types of solvents.

The coating liquid preferably contains components constituting the coating layer and a chemically inert surfactant from the viewpoint of promoting application to the resin base film.

Examples of the surfactant include anionic surfactants and nonionic surfactants. Specific surfactants include, for example, polyoxyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, and alkyl sulfosuccinic acid. Salt is an example.

The content of the surfactant is preferably 1% by mass to 10% by mass based on the total solid mass of the coating liquid. When the content of the surfactant is within the above range, the surface tension of the coating liquid can be set to 40 mN/m or less, so that repellency of the coating liquid can be prevented.

The coating liquid may contain additives other than the above-mentioned components. Examples of additives include resins other than the binder resin (for example, melamine resin), antistatic agents, and colorants. Examples of additives include soft polymers, fillers, heat stabilizers, weathering stabilizers, anti-aging agents, leveling agents, antistatic agents, slip agents, anti-blocking agents, antifogging agents, dyes, pigments, natural oils, Also included are synthetic oils, waxes, emulsions, fillers, hardeners, and flame retardants.

The solid content concentration of the coating liquid is usually 1% by mass to 20% by mass, preferably 1% by mass to 10% by mass. If the solid content concentration of the coating liquid is less than 1% by mass, the coating property on the resin base film tends to be insufficient. When the solid content concentration of the coating liquid exceeds 20% by mass, the stability of the coating liquid or the appearance of the coating tends to deteriorate.

The method for applying the coating liquid is not limited, and any known method can be used. Examples of methods for applying the coating liquid include roll coating, gravure coating, roll brushing, spray coating, air knife coating, impregnation, and curtain coating. In the method of applying the coating liquid, a single method may be used, or two or more methods may be used in combination.

The coating liquid can be applied to the resin base film at any stage. The coating liquid is preferably applied to the resin base film during the manufacturing process of the resin base film, and more preferably applied to the resin base film before oriented crystallization is completed. Here, the term "resin base film before crystal orientation is completed" refers to an unstretched film, a uniaxially stretched film obtained by orienting an unstretched film in either the longitudinal direction or the lateral direction, and an unstretched film. A biaxially stretched film obtained by stretching and orientating a film in two directions, the machine direction and the transverse direction, at a low magnification (however, this is limited to a biaxially stretched film that has not been re-stretched in the machine or transverse direction to complete orientation crystallization. ). Among the above, it is preferable to apply the coating liquid to an unstretched film or a uniaxially stretched film. After applying the coating liquid to an unstretched film or a uniaxially stretched film, it is preferable to perform longitudinal stretching and/or transverse stretching and heat setting.

When applying a coating liquid to a resin base film, it is preferable to perform physical treatment (e.g., corona surface treatment, flame treatment, and plasma treatment) on the surface of the resin base film as a preliminary treatment to improve coating properties. .

(Production method)
The resin base film and the resin used as a raw material for the resin base film can each be manufactured by a known method. Hereinafter, a method for manufacturing a resin base film using polyester as an example of resin will be described. A resin base film using a resin other than polyester can be manufactured with reference to the following method.

-Production method of polyester-
Methods for producing polyester include, for example, a method of directly obtaining a low polymerization degree polyester by reacting a carboxylic acid (e.g., terephthalic acid and naphthalene dicarboxylic acid) with glycol, and a method of transesterifying a lower alkyl ester of a dicarboxylic acid with a glycol. Examples include a method in which a reaction is performed using a catalyst and then polymerization is performed in the presence of a polymerization catalyst.

Examples of transesterification catalysts include compounds containing sodium, potassium, magnesium, calcium, zinc, strontium, titanium, zirconium, manganese, or cobalt. One type of transesterification catalyst may be used alone, or two or more types may be used in combination.

Examples of polymerization catalysts include antimony compounds (e.g., antimony trioxide and antimony pentoxide), germanium compounds (e.g., germanium dioxide), titanium compounds (e.g., tetraethyl titanate and its partial hydrolysates, tetrapropyl titanate and its partial hydrolyzate, tetraphenyl titanate and its partial hydrolyzate, titanyl ammonium oxalate, titanyl potassium oxalate, and titanium trisacetylacetonate).

When polymerizing via transesterification, a phosphorus compound may be added for the purpose of deactivating the transesterification catalyst before the polymerization reaction. Examples of phosphorus compounds include trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, and orthophosphoric acid (H ₃ PO ₄ ). The content of elemental phosphorus in the polyester is preferably from 20 ppm to 100 ppm by weight from the viewpoint of thermal stability of the polyester.

The polyester can also be chipped after melt polymerization and solid-state polymerized under heat and reduced pressure or in an inert gas flow (eg, nitrogen).

The intrinsic viscosity (35°C, orthochlorophenol) of the polyester constituting the resin base film is preferably 0.40 dl/g or more, more preferably 0.40 dl/g to 0.90 dl/g. . If the intrinsic viscosity is too low, process cutting tends to occur more easily. Furthermore, if the intrinsic viscosity is too high, the melt viscosity tends to increase, which tends to make melt extrusion difficult and also tends to lengthen the polymerization time. Note that if the intrinsic viscosity is too low, the hydrolysis resistance tends to decrease.

-Production method of polyester film-
A polyester film can be manufactured, for example, by the following method. Polyester is melt-extruded into a sheet and then cooled and solidified in a casting drum to form an unstretched film. The unstretched film is stretched once or twice or more in the longitudinal direction (referring to the axial direction of the film forming machine, also referred to as the longitudinal direction or MD) at Tg to Tg + 60°C so that the total magnification is 3 to 6 times. Then, the total magnification of one or more times in the width direction (meaning the direction perpendicular to the axis direction of the film forming machine and the thickness direction, also referred to as the transverse direction or TD) at Tg to Tg + 60 ° C. Stretch it 3 to 5 times. If necessary, the stretched film can be heat treated at Tm-80°C to Tm-20°C for 1 second to 60 seconds. Furthermore, if necessary, the stretched film can be reheated at a temperature 10° C. to 20° C. lower than the heat treatment temperature while shrinking the film by 0% to 20% in the width direction. In this paragraph, "Tg" represents the glass transition temperature (° C.) of polyester, which is the raw material for the resin base film. In this paragraph, "Tm" represents the melting point (°C) of the polyester that is the raw material for the resin base film. Moreover, the above-mentioned stretching may be sequential biaxial stretching or simultaneous biaxial stretching.

<<Thermocompression bonding process>>
The method for manufacturing a heat seal film according to the present disclosure includes a step of thermocompression bonding a heat sealing agent and a resin base film using a first compression bonding member (thermocompression bonding step).

The temperature in the thermocompression bonding process (that is, the temperature of thermocompression bonding) can be adjusted based on the temperature of at least the first compression bonding member. The temperature of the first pressure bonding member will be described later.

The pressure in the thermocompression bonding process (ie, the pressure of thermocompression bonding) is not limited. The pressure may be determined depending on, for example, the temperature of the first pressure bonding member, the composition of the heat sealing agent, and the composition of the resin base film. The pressure when thermocompression bonding the heat sealing agent and the resin base film is preferably 0.01 MPa to 5 MPa, more preferably 0.05 MPa to 3 MPa, and preferably 0.05 MPa to 2 MPa. Particularly preferred.

The method of thermocompression bonding the heat sealing agent and the resin base film is not limited as long as it uses the first compression bonding member. For example, by bringing the first pressure bonding member into contact with at least one of the heat sealing agent and the resin base film, the heat sealing agent and the resin base film can be thermocompression bonded.

In the thermocompression bonding step, it is preferable to thermocompress the heat sealant and the resin base film by bringing the first compression bonding member into contact with the heat sealant. By bringing the first pressure bonding member into contact with the heat sealing agent, the adhesion between the heat sealing agent and the resin base film can be improved.

When bringing the first pressure bonding member into contact with the heat sealant, the contact time between the first pressure bonding member and the heat sealant is preferably 1 second or more, more preferably 2 seconds or more, and 3 seconds or more. It is particularly preferable that the time is longer than seconds. By setting the contact time between the first pressure bonding member and the heat sealing agent to be 1 second or more, it is possible to improve the adhesion between the heat sealing agent and the resin base film. The upper limit of the contact time between the first pressure bonding member and the heat sealing agent is not limited, and may be determined depending on the temperature of the first pressure bonding member, the composition of the heat sealing agent, and the composition of the resin base film, for example. good. The contact time between the first pressure bonding member and the heat sealing agent may be determined within a range of, for example, 60 seconds or less.

In the thermocompression bonding process, the heat sealing agent and the resin base film are sandwiched between the first compression bonding member and the second compression bonding member facing the first compression bonding member. It is preferable to thermocompress the material film (for example, see FIGS. 1 and 2). By thermocompression bonding the heat sealing agent and the resin base film using the above method, the adhesion between the heat sealing agent and the resin base film can be improved. In the above method, from the viewpoint of improving the adhesion between the heat sealing agent and the resin base film, it is preferable to bring the first pressure bonding member into contact with the heat sealing agent. Specifically, the heat sealing agent and the resin base film are thermocompression bonded by bringing the first compression bonding member into contact with the heat sealing agent and by bringing the second compression bonding member into contact with the resin base film. is preferred.

When manufacturing a heat-sealing film having a resin base film, an easy-adhesive layer, and a heat-sealing agent in this order, the adhesive layer placed between the heat-sealing agent and the resin-based film in the thermocompression bonding process. It is preferable to bond the heat sealing agent and the resin base film by thermocompression via an adhesive layer. The easily adhesive layer is preferably placed on the resin base film before the thermocompression bonding process.

In the thermocompression bonding process, from the viewpoint of improving productivity, it is preferable to thermocompression bond the heat sealant and the resin base film while conveying the heat sealant and the resin base film.

In the method for producing a heat seal film according to the present disclosure, it is preferable to carry out the melt extrusion step and the thermocompression bonding step continuously. By carrying out the melt extrusion step and the thermocompression bonding step continuously, the number of steps can be further reduced and productivity can also be improved. "Continuously carrying out the melt extrusion process and the thermocompression bonding process" means that the thermocompression bonding process is carried out following the melt extrusion process without interruption in time. An example of a method for continuously performing the melt extrusion step and the thermocompression bonding step is a roll-to-roll method. The method for producing a heat seal film according to the present disclosure (specifically, the melt extrusion step and the thermocompression bonding step) is preferably carried out by a roll-to-roll method from the viewpoint of improving productivity.

[First crimp member]
The first pressure bonding member is not limited as long as it is a pressure bonding member whose temperature can be adjusted at least within the range of Tm-20°C to Tm+50°C. The number of first compression members used in the thermocompression bonding process may be one, or two or more.

The material for the first crimp member is not limited, and any known material can be used. Examples of the material of the first crimp member include metal (eg, stainless steel).

The surface of the first pressure bonding member may be subjected to surface treatment. For example, it is preferable that a layer containing a fluororesin is disposed on the surface of the first pressure bonding member. By disposing a layer containing a fluororesin on the surface of the first pressure bonding member, it is possible to suppress adhesion of raw materials (particularly heat sealing agent) to the surface of the first pressure bonding member. Examples of the fluororesin include polytetrafluoroethylene (PTFE) and tetrafluoroethylene/perfluoroalkoxyethylene copolymer resin (PFA).

From the viewpoint of improving productivity, the first pressure bonding member is preferably a roll, and more preferably a roll rotatable in the circumferential direction. Since the first pressure bonding member is a roll, the heat sealant and the resin base film can be thermocompression bonded while conveying the heat sealant and the resin base film. When the first pressure bonding member is a roll, it is preferable to thermocompress the heat sealant and the resin base film while conveying the heat sealant and the resin base film along the outer peripheral surface of the roll.

The size of the first crimp member is not limited. When the first pressure bonding member is a roll, the diameter of the first pressure bonding member may be determined within a range of, for example, 150 mm to 2000 mm.

The temperature of the first pressure bonding member is Tm-20°C to Tm+50°C. As mentioned above, Tm represents the melting point (° C.) of the resin contained in the heat sealing agent. The temperature of the first crimp member refers to the set temperature of the first crimp member that is adjusted by the temperature adjustment mechanism. By setting the temperature of the first pressure bonding member to Tm-20° C. or higher, it is possible to improve the adhesion between the heat sealing agent and the resin base film. By setting the temperature of the first pressure bonding member to Tm+50° C. or lower, thickness unevenness of the heat seal layer can be reduced.

The temperature of the first pressure bonding member is preferably Tm-20°C or higher, more preferably Tm-10°C or higher, even more preferably Tm+10°C or higher, particularly Tm+20°C or higher. Preferably, it is most preferably Tm+30°C or higher. By setting the temperature of the first pressure bonding member to Tm-20° C. or higher, the adhesion between the heat sealing agent and the resin base film can be further improved.

The temperature of the first pressure bonding member is preferably Tm+40°C or lower, more preferably Tm+30°C or lower, even more preferably Tm+20°C or lower, and particularly preferably Tm+10°C or lower. By setting the temperature of the first pressure bonding member to Tm+40° C. or lower, the thickness unevenness of the heat seal layer can be further reduced.

[Second crimp member]
In the thermocompression bonding step, a second compression bonding member may be used in addition to the first compression bonding member. The number of second compression members used in the thermocompression bonding process may be one, or two or more.

The second crimping member may be placed opposite to the first crimping member, or may be placed downstream of the first crimping member in the thermocompression bonding process.

Preferably, the second crimp member is disposed opposite the first crimp member. By disposing the second crimp member facing the first crimp member, there is a gap between the first crimp member and the second crimp member facing the first crimp member in the thermocompression bonding process. , the heat sealing agent and the resin base film can be sandwiched.

Examples of the material of the second pressure bonding member include metal (eg, stainless steel) and resin (eg, rubber and fluororesin).

The second pressure bonding member preferably has a layer containing a fluororesin on its surface. By disposing a layer containing a fluororesin on the surface of the first pressure bonding member, it is possible to suppress adhesion of raw materials. Examples of the fluororesin include polytetrafluoroethylene (PTFE) and tetrafluoroethylene/perfluoroalkoxyethylene copolymer resin (PFA).

The second pressure bonding member is preferably a roll, more preferably a roll rotatable in the circumferential direction. By using a roll as the second pressure bonding member, productivity can be improved.

The size of the second crimp member is not limited. When the second pressure bonding member is a roll, the diameter of the second pressure bonding member may be determined within a range of, for example, 150 mm to 2000 mm.

The temperature of the second pressure bonding member is not limited. The temperature of the second pressure bonding member may be determined, for example, in the range of 20°C to Tm+50°C. The temperature of the second crimp member refers to the temperature of the surface of the second crimp member. The temperature of the second pressure bonding member may be adjusted by a temperature adjustment mechanism, if necessary.

The temperature of the second compression member and the temperature of the first compression member may be the same or different. The temperature of the second pressure bonding member is preferably lower than the temperature of the first pressure bonding member from the viewpoint of uniformity of the thickness of the heat seal layer. Specifically, the temperature of the second pressure bonding member is preferably 1° C. or more lower than the temperature of the first pressure bonding member, more preferably 25°C or more lower, and even more preferably 50°C or more lower. The temperature of the second pressure bonding member is preferably 20°C to 150°C, more preferably 50°C to 150°C, particularly preferably 50°C to 100°C.

A method for manufacturing a heat seal film according to the present disclosure will be described with reference to the drawings. However, the dimensional ratios in the drawings do not necessarily represent the actual dimensional ratios. Components indicated using the same reference numerals in the drawings mean the same components. Descriptions of components and symbols that overlap in the drawings may be omitted.

FIG. 1 is a schematic diagram showing an example of a method for manufacturing a heat seal film according to the present disclosure. In FIG. 1, the first nip roll 40, the heating roll 30, and the second nip roll 50 are arranged along the conveyance direction (arrow direction).

In FIG. 1, a heating roll 30, which is an example of a first pressure bonding member, is arranged between a first nip roll 40 and a second nip roll 50. The heating roll 30 is rotatable in the circumferential direction. The temperature of the heating roll 30 is adjusted within the range of Tm-20°C to Tm+50°C.

In FIG. 1, a first nip roll 40, which is an example of a second pressure bonding member, is arranged facing the heating roll 30 on the upstream side in the conveyance direction (arrow direction). The heat sealing agent 10 and the resin base film 20 can be sandwiched between the heating roll 30 and the first nip roll 40. The first nip roll 40 is rotatable in the circumferential direction.

In FIG. 1, a second nip roll 50, which is an example of a second pressure bonding member, is arranged facing the heating roll 30 on the downstream side in the conveyance direction (arrow direction). The heat sealing agent 10 and the resin base film 20 can be sandwiched between the heating roll 30 and the second nip roll 50. The second nip roll 50 is rotatable in the circumferential direction.

In FIG. 1, the T-die 100 is arranged above the first nip roll 40. The T-die 100 can melt-extrude the heat sealant 10.

For example, as shown in FIG. 1, in the melt-extrusion process, the heat-sealing agent 10 is disposed on the resin base film 20 by melt-extruding the heat-sealing agent 10 from the T-die 100.

For example, as shown in FIG. 1, in the thermocompression bonding process, the heat sealing agent 10 and the resin base film 20 are conveyed in the conveying direction (arrow direction) along the outer peripheral surface of the heating roll 30, and the heat sealing agent 10 , and the resin base film 20 are passed between the heating roll 30 and the first nip roll 40 and then between the heating roll 30 and the second nip roll 50, thereby removing the heat sealing agent 10 and the resin base material. The film 20 is bonded by thermocompression. As shown in FIG. 1, by conveying the heat sealing agent 10 and the resin base film 20 along the outer peripheral surface of the heating roll 30, the contact time between the heat sealing agent 10 and the heating roll 30 can be lengthened. I can do it. By lengthening the contact time between the heat sealant 10 and the heating roll 30, the adhesion between the heat sealant 10 and the resin base film 20 can be improved.

In Figure 1, the temperature of the heat sealant from the time the heat sealant is melted and extruded until the start of thermocompression bonding between the heat sealant and the resin base film (transition period before thermocompression bonding) is determined at the measurement point. Measure at P10.

In FIG. 1, the temperature of the heat sealing agent after thermocompression bonding is measured at a measurement point P20.

FIG. 2 is a schematic diagram illustrating an example of a method for manufacturing a heat seal film according to the present disclosure. In FIG. 2, the heating roll 31, the first nip roll 41, and the second nip roll 51 are arranged along the conveyance direction (arrow direction).

In FIG. 2, a heating roll 31, which is an example of a first pressure bonding member, is arranged to face a first nip roll 41. The heat sealing agent 10 and the resin base film 20 can be sandwiched between the heating roll 31 and the first nip roll 41. The heating roll 31 is rotatable in the circumferential direction. The temperature of the heating roll 31 is adjusted within the range of Tm-20°C to Tm+50°C.

In FIG. 2, the first nip roll 41, which is an example of the second pressure bonding member, is arranged between the heating roll 31 and the second nip roll 51. The first nip roll 41 is rotatable in the circumferential direction.

In FIG. 2, a second nip roll 51, which is an example of a second pressure bonding member, is arranged opposite to the first nip roll 41. The heat sealing agent 10 and the resin base film 20 can be sandwiched between the first nip roll 41 and the second nip roll 51. The second nip roll 51 is rotatable in the circumferential direction.

In FIG. 2, the T-die 100 is arranged above the heating roll 31 and the first nip roll 41. The T-die 100 can melt-extrude the heat sealant 10.

For example, as shown in FIG. 2, in the melt-extrusion process, the heat-sealing agent 10 is disposed on the resin base film 20 by melt-extruding the heat-sealing agent 10 from the T-die 100.

For example, as shown in FIG. 2, in the thermocompression bonding process, the heat sealing agent 10 and the resin base film 20 are transported in the transport direction (arrow direction) along the outer peripheral surface of the first nip roll 41, and the heat sealing agent 10 and the resin base film 20 are transported in the transport direction (arrow direction) By passing the agent 10 and the resin base film 20 between the heating roll 31 and the first nip roll 41, the heat sealing agent 10 and the resin base film 20 are bonded by thermocompression. After thermocompression bonding, the heat sealing agent 10 and the resin base film 20 pass between the first nip roll 41 and the second nip roll 51.

In Figure 2, the temperature of the heat sealing agent and the thermocompression bonding from the time the heat sealant is melted and extruded until the start of thermocompression bonding between the heat sealant and the resin base film (transition period before thermocompression bonding) The temperature of the subsequent heat sealant is measured at measurement point P10.

In FIG. 2, the temperature of the heat sealing agent after thermocompression bonding is measured at a measurement point P20.

Hereinafter, the present disclosure will be explained in detail with reference to Examples. However, the present disclosure is not limited to the examples.

[Measuring method]
Each of the following characteristic values was measured by the following method.

(1) Melting point 10 mg of the sample was sealed in an aluminum pan for measurement. The above aluminum pan was attached to a differential scanning calorimeter (manufactured by TA Instruments, Model Q100 DSC), and the temperature was raised from 25°C to 200°C at a rate of 20°C/min to measure the melting point (Tm:°C).

(2) Peel strength A sample was prepared by cutting out a heat seal film to a width of 10 mm and a length of 150 mm, and peeling off the end of the heat seal layer whose adhesion was to be measured. The above sample was subjected to a 180 degree peel test at a peel rate of 100 mm/min in accordance with "JIS-K6854" using a tensile tester (Tensilon UCT-100 manufactured by Orientech Co., Ltd.). The measurement was performed three times, and the average value of the strengths excluding the initial peak value of each measurement was taken as the peel strength.

(3) Thickness unevenness Triangular samples (10 samples in total) were cut out from the heat seal film at 5 locations at 100 mm intervals in the width direction and at 5 locations at 500 mm intervals in the longitudinal direction. Each sample was fixed in an embedding capsule and then embedded in an epoxy resin. The embedded sample was cut in the longitudinal direction (thickness direction) using a microtome (ULTRACUT-S) to prepare thin film sections. Thin film sections were observed and photographed using an optical microscope. The thickness of the heat seal layer was measured from the obtained photograph. The thickness of the heat seal layer is the arithmetic average of the thicknesses at three locations. Among the thicknesses of the heat seal layer obtained from each photograph, the value obtained by subtracting the minimum value from the maximum value was defined as the thickness unevenness.

[Example 1-10 and Comparative Example 1-5]
In Example 1-10 and Comparative Example 1-5, heat seal films were produced based on the extrusion lamination method as shown in FIG.

A biaxially oriented polyester film (Q51, manufactured by Teijin Film Solutions Co., Ltd.) with a thickness of 125 μm was used as the resin base film. According to the description in Table 1, Admar QE840 (manufactured by Mitsui Chemicals, Inc.) or Admer VE300 (manufactured by Mitsui Chemicals, Inc.) was used as the component (resin) of the heat sealing agent. In the melt extrusion of the heat sealant, an extruder with a diameter of 65 mm was used to melt and extrude the heat sealant from a T-die. The take-up speed was adjusted so that the air gap was 100 mm, the film width was 750 mm, the thickness of the heat-sealing layer was 30 μm, and the contact time between the heating roll and the heat-sealing agent was as shown in Table 1.

The temperature of the heating roll (heating roll 30 shown in FIG. 1) was adjusted according to the description in Table 1.

The temperature of the first nip roll (first nip roll 40 shown in FIG. 1) was adjusted to 60°C.

The temperature of the second nip roll (second nip roll 50 shown in FIG. 1) was adjusted to 50°C.

The temperature of the heat sealing agent from the time the heat sealing agent is melt extruded until the start of thermocompression bonding between the heat sealant and the resin base film (transition period before thermocompression bonding), and the heat sealing after thermocompression bonding. The temperature of each agent is as listed in Table 1. The temperature of the heat sealant during the transition period before thermocompression bonding was measured at measurement point P10 shown in FIG. 1 using a non-contact thermometer (Hitester FT3701, manufactured by Hioki Electric Co., Ltd.; the same applies hereinafter). The temperature of the heat sealing agent after thermocompression bonding was measured at measurement point P20 shown in FIG. 1 using a non-contact thermometer.

The time from when the heat sealant is melt extruded until the start of thermocompression bonding between the heat sealant and the resin base film (transition time before thermocompression bonding), and the contact between the heating roll and the heat sealant during the conveyance process. The time (heat roll contact time) is as shown in Table 1.

The pressure during thermocompression bonding was adjusted to 0.05 MPa.

[Example 11-16 and Comparative Example 6-8]
In Examples 11-16 and Comparative Examples 6-8, heat seal films were produced based on the extrusion lamination method as shown in FIG.

A biaxially oriented polyester film (Q51, manufactured by Teijin Film Solutions Co., Ltd.) with a thickness of 125 μm was used as the resin base film. Admar QE840 (manufactured by Mitsui Chemicals, Inc.) or Admer VE300 (manufactured by Mitsui Chemicals, Inc.) was used as a component (resin) of the heat sealing agent. In the melt extrusion of the heat sealant, an extruder with a diameter of 65 mm was used to melt and extrude the heat sealant from a T-die. The take-up speed was adjusted so that the air gap was 100 mm, the film width was 750 mm, and the heat seal layer thickness was 30 microns.

The temperature of the heating roll (heating roll 31 shown in FIG. 2) was adjusted according to the description in Table 2.

The temperature of the first nip roll (first nip roll 41 shown in FIG. 2) was adjusted to 60°C.

The temperature of the second nip roll (second nip roll 51 shown in FIG. 2) was adjusted to 50°C.

Temperature of the heat sealant from melt extrusion of the heat sealant to the start of thermocompression bonding between the heat sealant and the resin base film (transition period before thermocompression bonding), and heat sealing after thermocompression bonding The temperature of each agent is as listed in Table 2. The temperature of the heat sealant during the transition period before thermocompression bonding was measured at measurement point P10 shown in FIG. 2 using a non-contact thermometer. The temperature of the heat sealing agent after thermocompression bonding was measured at measurement point P20 shown in FIG. 2 using a non-contact thermometer.

The time from melt extrusion of the heat sealant to the start of thermocompression bonding between the heat sealant and the resin base film (transition time before thermocompression bonding) is as shown in Table 2.

The pressure during thermocompression bonding was adjusted to 0.05 MPa.

The following symbols listed in the "Resin" column in Tables 1 and 2 each have the following meanings.
"A": Admer QE840 (manufactured by Mitsui Chemicals, Inc.)
"B": Admer VE300 (manufactured by Mitsui Chemicals, Inc.)

From Table 1, it was found that Examples 1 to 10 had better adhesion between the resin base film and the heat seal layer than Comparative Examples 1 to 5. From Table 2, it was found that Examples 11 to 16 had better adhesion between the base material and the heat seal layer than Comparative Examples 6 to 8.

In Examples 1 to 16, the process required in the conventional construction method of solidifying the heat sealing agent melt-extruded onto the resin base film before thermocompression bonding the resin base film and the heat sealing agent was performed. It turns out that it can be reduced.

The method for producing a heat-sealing film according to the present disclosure can produce a heat-sealing film with excellent adhesion between a base material and a heat-sealing layer through simple steps. Therefore, the heat-sealable film obtained by the method for producing a heat-sealable film according to the present disclosure can be suitably used even when exposed to various environments (for example, a moist heat environment).

10: Heat sealing agent 20: Resin base film 30, 31: Heating roll 40, 41: First nip roll 50, 51: Second nip roll 100: T die P10, P20: Measurement point

Claims (12)

a step of melt-extruding a heat sealing agent containing a resin;
a step of thermocompression bonding the heat sealing agent and the resin base film using a first compression bonding member;
When the melting point of the resin contained in the heat sealing agent is Tm, the temperature of the first pressure bonding member is Tm-20°C to Tm+50°C,
The temperature of the heat sealing agent after the heat sealing agent is melt extruded until the thermocompression bonding between the heat sealing agent and the resin base film is started is Tm-20°C or higher,
the resin base film is a polyester film,
Method for manufacturing heat seal film. a step of melt-extruding a heat sealing agent containing a resin;
a step of thermocompression bonding the heat sealing agent and the resin base film using a first compression bonding member;
When the melting point of the resin contained in the heat sealing agent is Tm, the temperature of the first pressure bonding member is Tm-20°C to Tm+50°C,
The temperature of the heat sealing agent after the heat sealing agent is melt extruded until the thermocompression bonding between the heat sealing agent and the resin base film is started is Tm-20°C or higher,
In the thermocompression bonding step, the heat sealant and the resin base film are thermocompression bonded via an easily adhesive layer disposed between the heat sealant and the resin base film.
Method for manufacturing heat seal film. a step of melt-extruding a heat sealing agent containing a resin;
a step of thermocompression bonding the heat sealing agent and the resin base film using a first compression bonding member;
When the melting point of the resin contained in the heat sealing agent is Tm, Tm is 120°C or more, and the temperature of the first pressure bonding member is Tm - 20°C to Tm + 50°C,
The temperature of the heat sealing agent after the heat sealing agent is melt-extruded until the thermocompression bonding between the heat sealing agent and the resin base film is started is Tm-20°C or higher;
Method for manufacturing heat seal film. Any one of claims 1 to 3, wherein the time from melt extrusion of the heat sealing agent to the start of thermocompression bonding between the heat sealing agent and the resin base film is 30 seconds or less. A method for producing a heat seal film as described in . The method for producing a heat seal film according to any one of claims 1 to 4, wherein the temperature of the first pressure bonding member is Tm-10°C to Tm+30°C. In the thermocompression bonding step, by sandwiching the heat sealing agent and the resin base film between the first compression member and a second compression member facing the first compression member, The method for producing a heat seal film according to any one of claims 1 to 5, wherein the heat seal agent and the resin base film are bonded by thermocompression. The method for manufacturing a heat seal film according to claim 6, wherein the second pressure bonding member is a roll. Any one of claims 1 to 7, wherein in the thermocompression bonding step, the heat sealant and the resin base film are thermocompression bonded by bringing the first compression bonding member and the heat sealant into contact with each other. A method for producing a heat seal film according to item 1. The method for producing a heat seal film according to claim 8, wherein the contact time between the first pressure bonding member and the heat sealing agent is 1 second or more. The method for producing a heat seal film according to any one of claims 1 to 9, wherein the first pressure bonding member is a roll. The method for producing a heat-sealing film according to claim 1 or 2, wherein the resin contained in the heat-sealing agent has a melting point Tm of 80°C to 150°C. The resin contained in the heat sealing agent is a polyolefin having at least one functional group selected from the group consisting of a carboxy group, a group having a carboxylic acid anhydride structure, and a hydroxy group. 12. The method for producing a heat seal film according to any one of 11.