Method of manufacturing multilayer body, and printing film

Abstract

To provide a method of manufacturing a multilayer body which has excellent heat lamination aptitude and wet / heat resistance (retort resistance) even when heat lamination is carried out at high speed.SOLUTION: There is provided a method of manufacturing a multilayer body comprising: a lamination film (A) having at least a base material layer (a) and a sealant layer; and a printing film (B) having at least a base material layer (b) and a printing layer. The lamination film (A) and the printing film (B) are heat welded and laminated. A maximum height (Sz) of the printing layer of the printing film (B) before lamination is 1000 nm or more and 15000 nm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a multilayer body and a printing film.

Background Art

[0002] As a technique for printing on packaging containers for beverages, foods, daily necessities, etc., liquid toner has attracted attention. It is known that liquid toner can form a color with a thinner film compared to conventional toner and can achieve a higher resolution of printed images.

[0003] In order to impart chargeability to liquid toner, a polymer having an ionic group is used as a material. For example, Patent Document 1 proposes a liquid toner in which a pigment is added to a polymer having a maleic anhydride functional group and an ethylene methacrylic acid copolymer and dispersed in a paraffin hydrocarbon fraction. This liquid toner exhibits excellent binding properties due to the interaction between the carboxyl group contained in maleic anhydride and the hydroxyl group of the base material paper.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, printed matter obtained by using the liquid toner disclosed in Patent Document 1 may deteriorate or deform in a wet-heat environment such as retort. Although the water resistance of the above printed matter can be improved by thermally laminating a protective film, it has been revealed that when thermally laminating at a certain speed or higher, bubbles are generated in a wet-heat environment such as retort. Therefore, an object of the present invention is to provide a method for manufacturing a multilayer body that is excellent in thermal lamination suitability and wet-heat resistance (retort resistance) even when thermally laminated at high speed. [Means for Solving the Problems]

[0006] As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. That is, the gist of the present invention is as follows.

[0007] [1] A method for manufacturing a multilayer body including a laminated film (A) having at least a base material layer a and a sealant layer, and a printed film (B) having at least a base material layer b and a printed layer, the method comprising thermally fusing and laminating the laminated film (A) and the printed film (B), and the maximum height (Sz) of the printed layer of the printed film (B) before lamination being 1000 nm or more and 15000 nm or less. [2] The method for manufacturing a multilayer body according to [1] above, wherein the sealant layer of the laminated film (A) and the printed layer of the printed film (B) are thermally fused and laminated. [3] The method for manufacturing a multilayer body according to [1] or [2] above, wherein the sealant layer contains an epoxy compound and a thermoplastic elastomer. [4] The method for manufacturing a multilayer body according to any one of [1] to [3] above, wherein the printed layer is formed by digital printing using a liquid toner method. [5] The method for manufacturing a multilayer body according to [4] above, wherein the liquid toner contains a polymer having an ionic group. [6] A printed film having at least a base material layer and a printed layer, wherein the maximum height (Sz) of the printed layer is 1000 nm or more and 15000 nm or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing a multilayer body that is excellent in heat lamination suitability and moisture and heat resistance (retort resistance) even when heat lamination is performed at high speed. [Embodiments for Carrying Out the Invention]

[0009] Embodiments of the present invention will be described in detail below. However, the content of the present invention is not limited to the embodiments described below.

[0010] [Method for manufacturing a multilayer body] The multilayer body in the present invention includes a laminated film (A) having at least a base material layer a and a sealant layer, and a printed film (B) having at least a base material layer b and a printed layer. The multilayer body is manufactured by thermally fusing and laminating (hereinafter sometimes referred to as "thermal lamination") the laminated film (A) and the printed film (B). At this time, it is preferable that the sealant layer of the laminated film (A) and the printed layer of the printed film (B) face each other and are thermally laminated.

[0011] In the laminated film (A) having at least the base material layer a and the sealant layer, the sealant layer may be provided on at least one surface of the base material layer a. Further, the sealant layer may be directly laminated on the surface of the base material layer a, or another layer may be appropriately provided between the sealant layer and the base material layer a. From the viewpoint of interlayer adhesion, it is preferable that a primer layer is provided between the sealant layer and the base material layer a. The sealant layer constituting the laminated film (A) preferably contains an epoxy compound, and more preferably further contains a thermoplastic elastomer.

[0012] On the other hand, in the printed film (B) having at least the base material layer b and the printed layer, the printed layer may be provided on at least one surface of the base material layer b, the printed layer may be directly laminated on the surface of the base material layer b, or another layer may be appropriately provided between the printed layer and the base material layer b. From the viewpoint of interlayer adhesion, it is preferable that a primer layer is provided between the printed layer and the base material layer b. The printed layer constituting the printed film (B) is preferably formed by digital printing using a liquid toner method, and the liquid toner preferably contains a polymer having an ionic group.

[0013] In addition to the laminated film (A) and the printed film (B) described above, the multilayer body according to the present invention may further have a functional layer having design properties, barrier properties, or the like laminated thereon.

[0014] In the multilayer body according to the present invention, the epoxy compound contained in the sealant layer of the laminated film (A) can react with the liquid toner component of the printed layer or the primer component of the primer layer of the printed film (B), thereby improving the moisture and heat resistance. Therefore, it can be suitably used as a packaging material that requires retort sterilization. The printed layer may be formed, for example, by printing a liquid toner with a known printing machine and appropriately drying it.

[0015] The liquid toner preferably contains a polymer having an ionic group capable of reacting with a cyclic ether group such as an epoxy group, and more preferably contains a carboxyl group-containing polymer. When the liquid toner contains a carboxyl group-containing polymer, since the reactivity with the epoxy compound is high, it can be more preferably used when the laminated film (A) contains an epoxy compound.

[0016] Examples of the method for producing the multilayer body of the present invention include a coextrusion method, a lamination method, a coating and drying method, etc., and a plurality of these can be combined. However, the step of thermally fusing and laminating the laminated film (A) and the printed film (B) is essential.

[0017] <Method for Producing Laminated Film (A)> As the method for producing the laminated film (A), a coextrusion method, a lamination method, a coating and drying method, etc. can be used. From the viewpoints of productivity and smoothness, a coating and drying method in which a sealant layer is formed on a substrate by coating and drying is preferable. When using the coating and drying method, it is preferable to use a solvent in which the resin composition constituting the sealant layer can be uniformly and stably dissolved or dispersed. Examples of such a solvent include petroleum benzine, toluene, xylene, benzene, ethylbenzene, hexane, cyclohexane, limonene, decalin, tetralin, chloroform, tetrahydrofuran, and the like. Among these solvents, toluene and limonene are preferred in terms of solubility and volatility.

[0018] The coating method in the coating and drying method is not particularly limited as long as it can achieve the required layer thickness and coating area. Examples of such coating methods include the gravure coater method, the small-diameter gravure coater method, the reverse roll coater method, the transfer roll coater method, the kiss coater method, the dip coater method, the knife coater method, the air doctor coater method, the blade coater method, the rod coater method, the squeeze coater method, the cast coater method, the die coater method, the screen printing method, the spray coating method, etc.

[0019] In the coating and drying process, a release film can be temporarily introduced for the purpose of preventing the adhesion and blocking of the sealant layer. More specifically, after passing through the coating process and the drying process, immediately before winding, a release film is placed on the sealant layer and integrated in the winding process. By this method, troubles during winding and transportation can be reduced, and the adhesion of foreign matters can be prevented. Note that the release film is usually removed when the laminated film (A) and the printed film (B) are finally laminated.

[0020] <Manufacturing method of the printed film (B)> The printed film (B) is obtained by subjecting a film (base material layer b) serving as a printing base material to surface treatment such as corona treatment or primer coating, and printing an arbitrary image by a printing machine. The base material film constituting the base material layer in the printed film (B) may be a single-layer film, but is preferably a multi-layer film from the viewpoints of the stiffness, heat resistance, and barrier properties of the film. Examples of the resins used for these include polyethylene, polypropylene, polyester, acrylic resin, polyamide resin, polystyrene, vinyl acetate, polyvinyl alcohol, and copolymers thereof. Such multi-layer films can be commercially available ones, but can also be obtained by thermal lamination, coextrusion, etc.

[0021] As surface treatment, corona treatment, plasma treatment, ozone treatment, primer treatment, etc. can be used, but from the viewpoints of simplicity and ink adhesion, combined use of corona treatment and primer treatment is preferable. Examples of primers include polyamine-based, acrylic-based, ethylene vinyl acetate-based, urethane-based, epoxy-based, etc., but polyamine-based is preferable in terms of adhesion.

[0022] As the printing machine, printing by a liquid toner printer is preferable from the viewpoint of resolution. Examples of liquid toner printers include HP Indigo 6K digital printer, HP Indigo 8K digital printer, HP Indigo 25K digital printer, HP Indigo 200K digital printer, etc.

[0023] <Thermal lamination method> As described above, in the present invention, the multilayer body is laminated by thermally laminating the laminated film (A) and the printed film (B). As the method of thermal lamination, a method of continuously pressing between a heating roll and a nip roll is preferable in terms of productivity. The linear pressure during thermal lamination is preferably 10 N / mm or more, more preferably 20 N / mm or more. On the other hand, it is preferably 800 N / mm or less, more preferably 400 N / mm or less. When the linear pressure is 10 N / mm or more, good interlayer adhesion can be obtained when forming the laminated film. On the other hand, when the linear pressure is 800 N / mm or less, the flow of the printing ink material can be suppressed. The temperature during thermal lamination is preferably 100°C or more and 180°C or less. When it is 100°C or more, good interlayer adhesion can be obtained when forming the multilayer body. On the other hand, when it is 180°C or less, wrinkles and film deformation during thermal lamination can be suppressed. The line speed during thermal lamination is preferably 0.1 m / min or more and 100 m / min or less. When it is 0.1 m / min or more, productivity is improved. Also, when it is 100 m / min or less, there is an effect of reducing production loss during job change.

[0024] (Thermal lamination suitability) In the method for manufacturing the multilayer body of the present invention, the laminated film (A) and the printed film (B) can be thermally laminated with good adhesion strength. In particular, it has suitability for thermal lamination at a high speed of about 10 m / min. In addition, the suitability for thermal lamination in the present invention can be evaluated, for example, by bonding the laminated film and the printed film by passing them through a nip roll heated to 110°C and then measuring the peel strength. The method for measuring the peel strength is based on the method described in the examples below.

[0025] (Moisture and heat resistance) By using the manufacturing method of the present invention, a multilayer body with good moisture and heat resistance can be obtained. In addition, the moisture and heat resistance in the present invention means that peeling between the laminated film (A) and the printed film (B) does not occur even in a moist and hot environment, and no change in appearance is caused, indicating retort resistance. More specifically, as described in the examples below, the multilayer body of the present invention can be evaluated by allowing it to stand in pressurized hot steam at 120°C for 0.5 hours and then observing the appearance.

[0026] (Thickness) The thickness of the present multilayer body is preferably 20 μm or more and 300 μm or less, more preferably 30 μm or more and 200 μm or less, and even more preferably 50 μm or more and 150 μm or less. When the thickness of the present multilayer body is 20 μm or more, the transportability and handleability during bag making are improved. On the other hand, when the thickness is 300 μm or less, the flexibility of the package after bag making is good.

[0027] Hereinafter, each layer will be described. 1. Base material layer The base material layer in the present invention is preferably the outermost surface layer that does not come into contact with each other when the laminated film (A) and the printed film (B) are thermally laminated. Any material commonly used for a base material layer can be used for the base material layer in the present invention. Specifically, examples include a thermoplastic resin film, a thermosetting resin film, a glass film, a metal foil, etc. Among them, from the viewpoint of suitability for secondary processing, it is preferable to contain a thermoplastic resin film, and it is more preferable to have a thermoplastic resin as the main component. The base material layers of the laminated film (A) and the printed film (B) may use different materials or those with different thicknesses. In the present invention, the "main component" refers to a component that occupies 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more (including 100% by mass) of all the components constituting the layer.

[0028] <Thermoplastic resin> Examples of the thermoplastic resin used in the present invention include polyolefin resins such as polypropylene and polyethylene, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyvinyl resins such as polystyrene, polyvinyl chloride, and polyvinyl acetate, acrylic resins such as polyacrylate, polymethacrylate, and polyacrylonitrile, and copolymers thereof. Among these, polyolefin resins and polyester resins are preferable in terms of strength and secondary processability.

[0029] Specific examples of the polyester resin include thermoplastic polyester resins represented by poly(ethylene glycol) terephthalate, poly(ethylene glycol) isophthalate, poly(ethylene glycol) succinate, poly(ethylene glycol) oxalate, poly(ethylene glycol) adipate, poly(butanediol) terephthalate, poly(hexanediol) terephthalate, poly(1,4-cyclohexanedimethanol) terephthalate, and copolymers thereof. These polyester resins can be used alone or in combination of two or more. Here, the copolymers mentioned herein mean those in which components other than the constituent components of each polymer are copolymerized, and the same applies hereinafter. The copolymerization may be graft polymerization or the like. Among these, poly(ethylene glycol) terephthalate is preferable in terms of excellent mechanical strength and heat resistance.

[0030] Specific examples of the polyolefin resin include polyethylene, polypropylene, polymethylpentene, and copolymers thereof represented by poly(ethylene-vinyl acetate) copolymer and maleic acid-modified polypropylene. These polyolefin resins can be used alone or in combination of two or more. Among these, polypropylene is preferable in terms of reducing the stickiness and tackiness of the film and having excellent interlayer adhesion and heat resistance with the sealant layer.

[0031] The base material layer may be a single layer or a multilayer. Even in the case of a multilayer, each layer is preferably mainly composed of a thermoplastic resin, and as the thermoplastic resin in each layer, it is preferable to use a polyolefin resin or a polyester resin. In the base material layer, a polyolefin resin and a polyester resin may be used in combination. For example, a multilayer base material layer may have both a layer mainly composed of a polyolefin resin and a layer mainly composed of a polyester resin. In the base material layer b of the printing film (B), as described above, it is preferably a multilayer film from the viewpoints of the firmness, heat resistance, and barrier properties of the film.

[0032] In addition to the above thermoplastic resin, the base material layer of the present invention may contain various additives such as plasticizers and curing agents. Further, the base material layer may be an unstretched film, or may be a uniaxially stretched or biaxially stretched film.

[0033] <Thickness> The thickness of the base material layer is preferably 5 μm or more and 100 μm or less, more preferably 7 μm or more and 90 μm or less, and even more preferably 8 μm or more and 80 μm or less. When the thickness of the base material layer is 5 μm or more, the transportability and handleability during heat lamination become good. On the other hand, when the thickness is 50 μm or less, the transparency of the present multilayer body becomes good.

[0034] 2. Sealant layer The laminated film (A) has a sealant layer on at least one surface of the above-described base material layer. The sealant layer in the present invention preferably contains an epoxy compound and a thermoplastic elastomer, and more preferably has a thermoplastic elastomer as a main component. By blending an epoxy compound with the thermoplastic elastomer, the heat and humidity resistance becomes even better. More specifically, it is known that the viscoelastic behavior of a general thermoplastic resin has a poor shape retention property around the heat-processable temperature range such as heat sealing because the elastic modulus rapidly decreases after melting. On the other hand, a material having a rubber component such as a thermoplastic elastomer has a viscoelastic behavior having a relatively soft rubbery flat region, and has a characteristic that the elastic modulus is high enough to maintain a certain shape even in the heat-processable temperature range such as heat sealing. That is, it is a useful property in the present invention that heat sealability and heat resistance must be compatible, and it is considered that blending an epoxy compound has an effect of making the rubbery flat region wider. Note that although part of the sealant layer may react and deteriorate over time, due to heat lamination, heat fusion with the printing layer, lamination of the primer layer, etc., the sealant layer before deterioration will be described below.

[0035] <Epoxy compound> The sealant layer of the present invention preferably contains an epoxy compound. When the sealant layer contains an epoxy compound, when the printing layer and the sealant layer are in contact, the ionic groups of the toner or ink components react with the epoxy compound, so the adhesiveness between the sealant layer and the printed matter is improved and the wet heat resistance becomes good. Also, when the sealant layer contains a thermoplastic elastomer, the polar groups of the thermoplastic elastomer react with the epoxy compound by heat, so that the thermoplastic elastomer is crosslinked and the molecular weight increases. Furthermore, the bleed-out of the epoxy compound is also suppressed, and there is also an effect of plasticizing the thermoplastic elastomer. Therefore, the heat lamination suitability during the production of this multi-layer body is also good.

[0036] As the epoxy compound, it is preferable that the epoxy equivalent is 10 g / eq or more and 200 g / eq or less. The epoxy equivalent is more preferably 50 g / eq or more, and even more preferably 100 g / eq or more. On the other hand, it is more preferably 195 g / eq or less, and even more preferably 190 g / eq or less. When the epoxy equivalent is 10 g / eq or more, there is an effect of suppressing gelation and improving productivity. On the other hand, when the epoxy equivalent is 200 g / eq or less, there is an effect of improving the wet heat resistance of the laminated film, the functional group density becomes high, the crosslinking reaction is likely to occur, and the bleed-out is also suppressed.

[0037] The epoxy compound preferably has an average number of functional epoxy groups per molecule of 1.3 or more. By having an average number of functional epoxy groups per molecule of 1.3 or more, the retort resistance can be improved. The average functionality of epoxy groups per molecule can be determined by dividing the average molecular weight by the epoxy equivalent. The average molecular weight can be measured by gas chromatography-mass spectrometry or high-performance liquid chromatography, and the epoxy equivalent can be measured by the measurement method specified in JIS K7236:2001. As described above, the average functionality of epoxy groups per molecule is preferably 1.3 or more, more preferably 1.4 or more, and even more preferably 1.5 or more. On the other hand, it is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. When the average functionality of epoxy groups per molecule is 5 or less, the solubility in the coating process can be improved.

[0038] Examples of the epoxy compound include monosubstituted epoxy compounds such as glycerol (poly) glycidyl ether, pentaerythritol (poly) glycidyl ether, and polyalkylene glycol diglycidyl ether, and disubstituted epoxy compounds such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized polybutadiene. These may be used alone or in combination of two or more. Further, the epoxy compound may partially contain unreacted substances or overreacted substances. Among the above, monosubstituted epoxy compounds are preferred from the viewpoints of reactivity, heat resistance, and compatibility. Among them, polyalkylene glycol diglycidyl ether is preferred, and among them, those having a weight average molecular weight of 200 or more and 500 or less are more preferred. Note that (poly) glycidyl ether is a concept including both monoglycidyl ether and polyglycidyl ether, and similar terms have the same meaning.

[0039] The surface tension (SP value) of the epoxy compound is preferably 8 or more, more preferably 8.5 or more, from the viewpoint of compatibility. On the other hand, it is preferably 20 or less, more preferably 18 or less, from the viewpoint of heat and humidity resistance. The surface tension (SP value) can be calculated using the following formula (1) by the Fedors method. SP value (solubility parameter) = (CED value) 1 / 2=(E / V) 1 / 2 (1) In formula (1), E is the molecular aggregation energy (cal / mol), and V is the molecular volume (cm 3 / mol). When the evaporation energy of the atomic group is Δei and the molar volume is Δvi, they are represented by the following formula (2) and formula (3). E = ΣΔei (2) V = ΣΔvi (3)

[0040] The content of the epoxy compound in the sealant layer is preferably 0.1% by mass or more and 20% by mass or less based on the total mass of the sealant layer. By being 0.1% by mass or more, the heat and humidity resistance becomes good. On the other hand, by being 20% by mass or less, there is an effect of suppressing the bleed-out of the epoxy compound, suppressing the decrease in adhesion strength over time, and suppressing appearance defects. From the above viewpoints, the content of the epoxy compound in the sealant layer is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 18% by mass or less, and even more preferably 1% by mass or more and 15% by mass or less.

[0041] <Thermoplastic elastomer> The thermoplastic elastomer preferably has a polar group, and as the polar group, an acidic functional group is preferred. Examples of the acidic functional group include groups derived from carboxylic acids, acid anhydrides, carboxylic acid halides, sulfonic acids, etc. From the viewpoint of easy availability, groups derived from carboxylic acids or acid anhydrides are preferred. Since the thermoplastic elastomer of the present invention has a polar group, particularly an acidic functional group, the bleed-out of the epoxy compound can be suppressed, and the heat lamination suitability can be made better. As the thermoplastic elastomer, a thermoplastic elastomer having an acidic functional group may be used alone, or may be used in combination with a thermoplastic elastomer having no acidic functional group or a thermoplastic elastomer having a polar group other than the acidic functional group.

[0042] When the thermoplastic elastomer has an acidic functional group, its acid value is 1 mgCH 35 mg CH or more per g of ONa 3 preferably 1.2 mg CH or less per g of ONa 3 more preferably 4.5 mg CH or more per g of ONa 3 more preferably 1.5 mg CH or less per g of ONa 3 even more preferably 4 mg CH or more per g of ONa 3 even more preferably 1 mg CH or less per g of ONa The acid value is 1 mg CH 3 When the acid value is 1 mg CH or more per g of ONa, the heat lamination suitability becomes better. On the other hand, when the acid value is 5 mg CH 3 When it is 5 mg CH or less per g of ONa, the stability over time becomes better. The acid value of the thermoplastic elastomer is measured by the Asahi Kasei method described in JP-A-2002-202301. Since the thermoplastic elastomer having an acidic functional group is produced by radically adding maleic anhydride to the thermoplastic elastomer, it often contains unreacted free maleic anhydride. However, the acid value of the above resin composition means a value including the free maleic anhydride content without removing the free maleic anhydride.

[0043] Examples of the thermoplastic elastomer include conjugated diene polymers and hydrogenated products of conjugated diene polymers. Among them, a hydrogenated product of a conjugated diene polymer is preferable. By being a hydrogenated product, there is an effect of suppressing oxidative degradation. Examples of the conjugated diene polymer include styrene-butadiene copolymers (styrene-butadiene rubber), styrene-isoprene copolymers (styrene-isoprene rubber), acrylonitrile-butadiene copolymers (acrylonitrile-butadiene rubber), butadiene rubber, isoprene rubber, chloroprene rubber, and copolymers thereof. These may be used alone or in combination of two or more.

[0044] Among these, from the viewpoints of availability, heat resistance, and film-forming properties, a copolymer containing a styrene unit is preferable, and a copolymer containing a styrene unit and any repeating unit different from the styrene unit is more preferable. In the present invention, the "styrene unit" means a repeating unit obtained when styrene is polymerized. When the thermoplastic elastomer is a copolymer containing a styrene unit and any repeating unit different from the styrene unit, the styrene polymerization ratio is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of solubility in a solvent. On the other hand, from the viewpoint of heat laminating properties, it is preferably 50% by mass or less, more preferably 40% by mass or less. Examples of the copolymer containing a styrene unit and any repeating unit different from the styrene unit include styrene-butadiene copolymers (styrene-butadiene rubber) and styrene-isoprene copolymers (styrene-isoprene rubber), with styrene-butadiene copolymers being more preferable, and hydrogenated products of styrene-butadiene copolymers being even more preferable. Further, the styrene-butadiene copolymer is more preferably a block copolymer of styrene and butadiene. When the thermoplastic elastomer is a copolymer containing styrene, the styrene polymerization ratio is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of solubility in a solvent. On the other hand, from the viewpoint of heat laminating properties, it is preferably 50% by mass or less, more preferably 40% by mass or less.

[0045] The thermoplastic elastomer is preferably an acid-modified conjugated diene polymer. Since the conjugated diene polymer has a carbon-carbon double bond in its molecular skeleton, it is known that an acidic functional group can be imparted, that is, acid-modified, by radically adding an unsaturated carboxylic acid (and acid anhydride) such as acrylic acid or maleic anhydride. Among the above acid modifications, maleic anhydride modification is preferable from the viewpoint of availability. The above-mentioned acid-modified conjugated diene copolymer can also be obtained as commercial products such as "Tuftec: M1911, M1913, M1943 (Asahi Kasei Corporation)", "Tufprene: 912 (Asahi Kasei Corporation)", and "Clayton FG Polymer: FG1901, FG1924 (Clayton Corporation)".

[0046] From the viewpoint of heat and humidity resistance, the elastic modulus of the above-mentioned thermoplastic elastomer is preferably 0.5 GPa or more, more preferably 0.7 GPa or more, in the range of the measurement temperature from 100 to 110 °C. On the other hand, from the viewpoint of heat laminating property, it is preferably 10 GPa or less, more preferably 5 GPa or less, in the range of the measurement temperature from 100 to 110 °C. The elastic modulus can be measured by a dynamic viscoelasticity measuring device (DMA).

[0047] The iodine value of the above-mentioned thermoplastic elastomer is preferably 50 or less, more preferably 30 or less. When the iodine value is 50 or less, the remaining amount of double bonds in the thermoplastic elastomer is sufficiently small, and the deterioration of physical properties due to oxidation can be suppressed, which is preferable. The iodine value can be measured according to JIS K0070-1992.

[0048] In the sealant layer in the multilayer body according to the present invention (hereinafter, may be described as "the sealant layer of the present invention"), the content ratio (mass ratio) of the above-mentioned thermoplastic elastomer and the epoxy compound is preferably 0.01 or more, more preferably 0.02 or more, of the epoxy compound with respect to the thermoplastic elastomer from the viewpoint of heat and humidity resistance. On the other hand, from the viewpoint of heat laminating property, it is preferably 0.4 or less, more preferably 0.25 or less.

[0049] In the sealant layer, the content of the above-mentioned thermoplastic elastomer is preferably 50% by mass or more and 99.9% by mass or less, more preferably 55% by mass or more and 95% by mass or less, still more preferably 60% by mass or more and 90% by mass or less. When the content of the thermoplastic elastomer is 50% by mass or more, the moisture and heat resistance is good. On the other hand, when the content is 99.9% by mass or less, the addition effect of the aforementioned epoxy compound can be obtained and the winding property of the laminated film is good.

[0050] <Flow start temperature> The flow start temperature of the sealant layer of the present invention is preferably 80°C or higher and 105°C or lower, more preferably 83°C or higher and 102°C or lower, and even more preferably 85°C or higher and 100°C or lower. When the flow start temperature is 80°C or higher, the moisture and heat resistance is good. On the other hand, when the flow start temperature is 105°C or lower, the heat lamination suitability is good. Note that the flow start temperature of the sealant layer of the present invention is measured by the method described below. Further, the flow start temperature of the resin composition of the present invention can be adjusted by appropriately selecting the type of the thermoplastic elastomer and / or the epoxy compound.

[0051] (Measurement method of flow start temperature) The flow start temperature of the sealant layer of the present invention can be measured using a Koka type flow tester "CFT-500D" manufactured by Shimadzu Corporation. For the measurement, a nozzle of 1mmφ×2mmL is used, and the load is 40kg / cm 2 As, the process from the solid through the rubbery elastic region to the flow region of the test piece heated at a rate of 3°C / min is continuously measured, and the temperature at which it flows out from the nozzle is determined.

[0052] <Acid value> The acid value of the sealant layer of the present invention is 0.5mgCH 3 ONa / g or more and 4.3mgCH 3 It is preferably ONa / g or less. When the acid value of the sealant layer is 0.5mgCH 3 Since it is ONa / g or more, it maintains appropriate fluidity and has reactive active groups, so more excellent heat lamination suitability and moisture and heat resistance can be obtained. On the other hand, when the acid value of the sealant layer is 4.3mgCH 3By being below ONa / g, excessive crosslinking and hardening of reactive functional groups are suppressed, resulting in the effect that the thermal lamination suitability and stability over time are further improved. From the above viewpoints, the acid value of the sealant layer of the present invention is 0.7 mgCH 3 It is more preferably at least ONa / g, and more preferably at least 1.0 mgCH 3 It is even more preferably at least ONa / g. On the other hand, it is more preferably at most 3.8 mgCH 3 It is more preferably at most ONa / g, and even more preferably at most 3.6 mgCH 3 It is even more preferably at most ONa / g. Note that the acid value of the sealant layer of the present invention is measured by the Asahi Kasei method described in JP-A-2002-202301. More specifically, it can be measured by the procedure described in the examples below. In addition, the acid value of the above-mentioned sealant layer means a value including maleic anhydride content without removing free maleic anhydride. Examples of methods for controlling the acid value include adjusting the polymerization ratio of acidic monomers of the thermoplastic elastomer, adding an acid, adding a neutralizing agent, esterification / amidation modification of acidic groups, and removing free acid by purification.

[0053] <Loss tangent (tanδ)> The loss tangent (tanδ) in the dynamic viscoelasticity measurement at a frequency of 10 Hz of the sealant layer of the present invention preferably has a maximum value at 50°C or higher and 80°C or lower. By the maximum value of the loss tangent (tanδ) being 50°C or higher, the effects of improved heat and humidity resistance and adhesion strength can be obtained. On the other hand, by the maximum value of the loss tangent (tanδ) being 80°C or lower, a state where a tacky feeling is easily exhibited during thermal lamination is achieved, and excellent thermal lamination suitability, particularly thermal lamination suitability at a low temperature of about 90°C, can be obtained. Furthermore, the maximum value of the loss tangent (tanδ) is more preferably 52°C or higher, and even more preferably 55°C or higher. On the other hand, it is more preferably 78°C or lower, and even more preferably 75°C or lower.

[0054] The loss tangent (tanδ) in the dynamic viscoelasticity measurement at a frequency of 10 Hz of the sealant layer of the present invention can be determined by producing a film of the resin composition alone and measuring this film with a dynamic viscoelasticity measuring device (DMA). More specifically, it can be measured according to the procedure described in the examples below. Also, as a method for producing the film of the resin composition alone, in order to exclude the possibility of reaction by heat, it is preferably produced by solvent casting. As the solvent, aromatic hydrocarbons such as benzene, toluene, and xylene, and aliphatic hydrocarbons such as limonene and pinene can be preferably used. When producing by solvent casting, in order to exclude the possibility of reaction by heat, natural drying is preferred, and in order to exclude the influence of residual solvent, vacuum drying is preferably performed thereafter. More specifically, it can be produced according to the method described in the examples below. Regarding the loss tangent (tanδ) in the dynamic viscoelasticity measurement at a frequency of 10 Hz of the sealant layer of the present invention, for example, it can be controlled by the styrene / diene polymerization ratio and acid value of the thermoplastic elastomer, the molecular skeleton and content of the epoxy compound, and the addition of other components. More specifically, the higher the styrene ratio of the thermoplastic elastomer, the higher the acid value, the shorter the alkyl chain length of the epoxy compound, and the lower the content of the epoxy compound, the higher the temperature at which the loss tangent (tanδ) takes a maximum value can be.

[0055] The sealant layer of the present invention may further contain components such as a stabilizer, an antioxidant, and a filler in addition to the thermoplastic elastomer and the epoxy compound.

[0056] [Other components] The materials constituting the sealant layer of the present invention may contain a reaction aid, other resins, a plasticizer, a filler, an antioxidant, etc. as components other than the above-mentioned thermoplastic elastomer and epoxy compound for the purpose of improving the reactivity, transparency, antiblocking property, and gelation of the sealant layer.

[0057] [Thickness] The thickness of the sealant layer is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 25 μm or less, and even more preferably 3 μm or more and 20 μm or less. When the thickness of the sealant layer is 1 μm or more, the thermal lamination suitability during the production of the multilayer body of the present invention becomes good. On the other hand, when the thickness is 30 μm or less, the transparency of the multilayer body becomes good.

[0058] 3. Printing layer The printing film (B) has a printing layer on at least one surface of the base material layer. The printing method is not particularly limited. In addition to various known plate printing methods such as gravure printing, offset printing, flexographic printing, seal printing, and screen printing, digital printing by various printers such as inkjet method, electrophotographic method, or liquid toner method, and melt thermal transfer printing can also be performed. In the production of the present multilayer body, among the above printing methods, it is preferably formed by digital printing using the liquid toner method from the viewpoint of high resolution. The printing layer does not necessarily have to be formed over the entire surface of the film, and a desired pattern or design can be printed.

[0059] In the production method of the present invention, it is important to control the maximum height (Sz) of the printing layer of the printing film (B) to be 1000 nm or more and 15000 nm or less. When the maximum height (Sz) of the printing layer is 1000 nm or more, excellent adhesion of the multilayer body can be obtained. On the other hand, when the maximum height (Sz) of the printing layer is 15000 nm or less, the entrapment of microscopic air during thermal lamination can be suppressed, and foaming during retort processing can be suppressed. The maximum height (Sz) of the printing layer can be measured by the method described in the examples below. From the above viewpoints, the maximum height (Sz) of the printing layer is preferably 2000 nm or more, more preferably 3000 nm or more, even more preferably 5000 nm or more, and particularly preferably 10000 nm or more. On the other hand, it is preferably 14000 nm or less, and even more preferably 13000 nm or less. As a method for controlling the maximum height (Sz) of the printing layer within the above-described range, although not particularly limited, examples include a method of controlling the dot pattern during printing and adjusting the ink overlay, a method of roll-pressing the film after printing, and a method of forming an absorbent layer on the base of the printing layer. Among these, the method of roll-pressing the film after printing is preferred because it is simple.

[0060] The printing layer may be formed directly on the surface of the base material layer, or may be formed on a primer layer provided on the surface of the base material layer.

[0061] 4. Primer layer In the production of this multilayer body, it is preferable to provide a primer layer between the sealant layer and the base material layer of the laminated film (A) or between the printing layer and the base material layer of the printed film (B). By providing the primer layer, the adhesion between the layers can be improved.

[0062] The primer layer preferably comprises a composition containing a resin as a main component. As the main component resin, resins commonly used as primer resins in the printing industry can be used. For example, polyethyleneimine, polyvinyl acetate, polyacrylic acid, polyvinyl alcohol, polyvinyl acetal, polyester, polyvinyl acetamide, polyvinyl pyrrolidone, etc. can be mentioned. Among these, from the viewpoint of solvent resistance when forming the sealant layer of the present invention, polyethyleneimine, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, and polyester are preferred, and from the viewpoint of adhesion to the sealant layer of the present invention, polyethyleneimine is more preferred. These may be used alone or in combination of two or more.

[0063] The thickness of the primer layer is preferably 0.01 μm or more and 10 μm or less, more preferably 0.05 μm or more and 7 μm or less, and even more preferably 0.1 μm or more and 5 μm or less. When the thickness of the primer layer is 0.01 μm or more, there is an effect of reducing optical appearance defects of the film. On the other hand, when the thickness of the primer layer is 10 μm or less, excellent adhesion can be obtained.

[0064] 5. Other Layers The laminated film (A) and the printed film (B) may each have other layers. For example, they may have an inorganic barrier layer. Examples of the inorganic barrier layer include a silica vapor deposition film, an aluminum vapor deposition film, a diamond-like carbon film, etc. Since these inorganic barrier layers have low abrasion resistance, they are preferably laminated on a layer that is not the outermost surface.

[0065] <Package> The multilayer body obtained by the production method of the present invention may be used for a package for packaging various articles. For example, it may be used as a package formed on the surface. Since the multilayer body according to the present invention has good heat and humidity resistance, it has excellent retort suitability and can be suitably used as a packaging film. Further, it is more preferable that a package such as a packaging film is used for retort.

[0066] <Packaged Article> The packaged article using the multilayer body obtained by the production method of the present invention is a package of various articles such as beverages, foods, daily necessities, etc., or a container for storing various articles, using the above-described package. The packaging mode is not particularly limited, and various articles may be stored inside a package formed into a bag shape, a container shape, etc., or a part or all of an article or a container for storing an article may be wrapped with the package.

[0067] [Printed Film] The above-described printed film (B) is also within the scope of the present invention. That is, a printed film having at least a base material layer and a printing layer, wherein the maximum height (Sz) of the printing layer is 1000 nm or more and 15000 nm or less, is also within the scope of the present invention. The base material layer and the printing layer are as described above, and the maximum height (Sz) of the printing layer is also as described above.

[0068] In the present invention, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as the meanings of "preferably greater than X" and "preferably less than Y". Further, in the present invention, when expressed as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when expressed as "Y or less" (Y is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably less than Y".

Example

[0069] Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to the examples described below, and various modifications are possible without departing from the gist of the present invention.

[0070] <Materials constituting each layer> [Base material layer] (Thermoplastic resin) A-1: Polyester (using corona-treated biaxially oriented film: thickness 12 μm, product name "Diafoil H600C", manufactured by Mitsubishi Chemical Corporation) [Sealant layer] (Thermoplastic elastomer) E-1: Hydrogenated styrene-butadiene elastomer (product name "Tuftec M1911", manufactured by Asahi Kasei Corporation, acid value: 2 mg CH 3 ONa / g) (Epoxy compound) B-1: Polypropylene glycol diglycidyl ether (product name: "Denacol EX-920", average number of functional epoxy groups per molecule: 1.57, epoxy equivalent: 176 g / eq, manufactured by Nagase ChemteX Corporation) [Release layer] D-1: Release polyester film (thickness 38 μm, product name "Diafoil MRF-38", manufactured by Mitsubishi Chemical Corporation)

[0071] Example 1 <Manufacture of laminated film (A)> On one side of the base material layer A-1, using a gravure roller, polyethyleneimine (product name: "Epomin P1000", manufactured by Nippon Shokubai Co., Ltd.) with a weight fraction of 0.15 g / m 2 was applied, and then dried to form a primer layer. Subsequently, 20 parts by mass of the thermoplastic elastomer E-1 and 1 part by mass of the epoxy compound B-1 were dissolved in 80 parts by mass of toluene, and aged by stirring at 100 °C for 3 hours to obtain a toluene solution of the resin composition. The acid value of this resin composition was 3.1 mgCH 3 ONa / g, and the loss tangent (tanδ) in the dynamic viscoelasticity measurement at a frequency of 10 Hz showed a maximum value at 61 °C. The toluene solution of this resin composition was applied onto the primer layer to a WET thickness of 20 μm and dried at 90 °C for 1 minute. After drying, a release polyester film was overlaid so that the coated surface faced the release surface of the release layer D-1, thereby obtaining the laminated film (A) of Example 1.

[0072] <Manufacture of the printed film (B)> A nylon film (product name: "Harden N1200", manufactured by Toyobo Co., Ltd., thickness 15 μm) and an unstretched polypropylene film (product name: "FRTK-G", manufactured by Futamura Chemical Co., Ltd., thickness 50 μm) were laminated in this order by dry lamination. For the lamination by dry lamination, a urethane-based adhesive (product name: "Takelac A-515V / Takenate A-5", manufactured by Mitsui Chemicals, Inc.) was used and applied with a gravure plate so that the coating amount during drying was 3.5 g / m 2 . After lamination, aging was performed at 40 °C for 48 hours. Then, the nylon film side was corona-treated, and as a primer, polyethyleneimine (product name: "Epomin P1000", manufactured by Nippon Shokubai Co., Ltd.) was used and applied using a gravure roller to coat the entire surface of the nylon film side with a weight of 0.15 g / m 2 . Next, using an HP Indigo 6600 digital printing press, the printing layer was solid-printed on one side with HP Indigo electroink with the cyan, magenta, and black outputs set to 100% on the surface where the primer was applied. Thereby, a printed sample was obtained. This printed sample was passed between a φ200 mm roll at a temperature of 110°C and a roll with a nip pressure of 0.4 MPa at a speed of 10 m / min, and a printed film (B) was obtained by performing a surface smoothing treatment. At this time, the maximum height (Sz) of the printed layer was 11,800 nm. The maximum height was measured at three arbitrary points (field area 600 μm × 450 μm) on the printed surface using a Bruker Contour GT-X (filter: White, objective lens: 10x, FOV lens: 1x, back scan length: 5, scan length: 25), and the average value of these three points was taken.

[0073] [Method for manufacturing a multilayer body] The release layer D-1 was peeled off from the laminated film (A) of Example 1, the printed surface of the above-mentioned printed film (B) was opposed to that surface, and it was passed between a metal roll heated to 110°C and a nip roll so that the printed film (B) was on the nip roll side at a linear speed of 10 m / min, thereby obtaining the multilayer body of Example 1.

[0074] Example 2 In Example 1, a multilayer body was obtained in the same manner as in Example 1 except that the ink used to produce the printed film (B) was changed to only magenta 1 color and the surface smoothing treatment was not performed. At this time, the maximum height (Sz) of the printed layer was 12,100 nm.

[0075] Comparative Example 1 In Example 1, a multilayer body was obtained in the same manner as in Example 1 except that the surface smoothing treatment of the printed film (B) was not performed. At this time, the maximum height (Sz) of the printed layer was 16,200 nm.

[0076] Comparative Example 2 In Example 1, a multilayer body was obtained in the same manner as in Example 1 except that the polyester film made of the polyester A-1 was used as it was instead of the laminated film (A).

[0077] [Measurement and evaluation methods] For Examples 1 to 2 and Comparative Examples 1 to 2, the maximum temperature of the loss tangent (tanδ) in the dynamic viscoelasticity measurement at the above-mentioned various thicknesses, acid value of the thermoplastic elastomer, and frequency of 10 Hz was measured by the following methods (1) to (3). In addition, the following evaluations (4) and (5) were performed on the multilayer bodies obtained in Examples 1 to 2 and Comparative Examples 1 to 2. The results of each evaluation are shown in Table 1.

[0078] (1) Thickness The thicknesses of the base material layer, the release layer, and the laminated film (A) were measured at five unspecified locations with a dial gauge of 1 / 1000 mm, and the average value was determined therefrom. Regarding the thickness of the sealant layer, it was calculated by subtracting the thicknesses of the base material layer and the release layer from the thickness of the laminated film (A).

[0079] (2) Acid value of the thermoplastic elastomer (Asahi Kasei method) Regarding the acid value of the thermoplastic elastomer, after dissolving the resin composition in toluene, thymol blue was added, and a 1 wt% or 0.1 wt% sodium methoxide / methanol solution was added dropwise, and titration was performed with the end point being the point where the blue color was maintained for 1 minute or more.

[0080] (3) Maximum temperature of the loss tangent (tanδ) in the dynamic viscoelasticity measurement of the thermoplastic elastomer at a frequency of 10 Hz Regarding the maximum temperature of the loss tangent (tanδ), after preparing a film of the resin composition alone, a dynamic viscoelasticity measuring device ("DVA-20" manufactured by IT Measurement & Control Co., Ltd.) was used and the film obtained using a tensile jig was fixed, and the storage elastic modulus was measured at a measurement temperature of -100 to 250°C, a frequency of 10 Hz, and a heating rate of 3°C / min. The ratio (E' / E") of the storage elastic modulus (E') to the loss elastic modulus (E") was plotted against the temperature, the maximum value was read, and the temperature (maximum temperature) showing the maximum value was determined. (Method for preparing a film of the resin composition alone) The film of the resin composition alone was prepared as follows. After dissolving the resin composition in toluene so that it became 20% by mass, this solution was cast onto a polyethylene flat plate to a thickness of about 0.5 mm and naturally dried at room temperature for 24 hours. Then, by vacuum drying at room temperature for 6 hours, a film of the resin composition alone with a thickness of 100 μm was obtained.

[0081] (4) Heat lamination suitability Regarding the obtained multilayer body, the peel strength between the laminated film (A) and the printed film (B) was measured by the following method, and the heat lamination suitability was evaluated according to the following evaluation criteria. ○ (good): Peel strength is 1.5 N / 15 mm or more × (poor): Peel strength is less than 1.5 N / 15 mm

[0082] (Measurement of peel strength) In accordance with JIS Z0237, the peel strength between the laminated film (A) and the printed film (B) of the multilayer body was measured. First, as a sample, the multilayer body was cut out to a size of 50 mm in width × 150 mm in length. Cellophane tape (manufactured by Nichiban Co., Ltd., JIS Z1522) was attached to the longitudinal direction of the surface of the laminated film (A) of the sample, folded back at 90° so that the back of the tape overlapped, and peeled off 25 mm from the sample. Next, one end of the sample of the peeled part was fixed to the lower chuck of a tensile testing machine (manufactured by Intesco Co., Ltd., Intesco IM-20ST), the tape was fixed to the upper chuck, and the peel strength was measured at a test speed of 300 mm / min. After the measurement, the measured value of the first 25 mm length was ignored, and the average of the peel strength measured values of the 50 mm length peeled off from the test piece was taken as the peel strength. In addition, when the laminated film (A) did not peel off and only the tape peeled off, the peel strength of the multilayer body was regarded as being equal to or greater than the peel strength of only the tape.

[0083] (5) Damp heat resistance (retort resistance) Regarding the multilayer body, using a pressure cooker tester (manufactured by Espec Corporation: EHS-411M), it was processed in high-pressure steam set at 120 °C for 0.5 hours, and the appearance after the treatment was evaluated according to the following criteria. In Comparative Example 2, since the thermal lamination was defective and partial peeling had already occurred, the retort resistance could not be evaluated. ○ (good): There are no bubbles on the entire surface of the film. × (poor): Bubbles are generated in part.

[0084]

Table 1

[0085] Regarding the printing ink in Table 1, "C" means cyan, "M" means magenta, and "K" means black.

[0086] In Examples 1 to 2 where the maximum height of the printing layer is 1000 nm or more and 15000 nm or less, a multilayer body excellent in thermal lamination suitability and heat and humidity resistance (retort resistance) at 110 °C was obtained. On the other hand, in Comparative Example 1 where the maximum height of the printing layer is 15000 nm or more, the retort resistance became insufficient. This is presumably because micro air entrainment occurred during thermal lamination. In Comparative Example 2 without a sealant layer, sufficient thermal lamination properties were not exhibited.

Industrial Applicability

[0087] The method for manufacturing the laminate of the present invention can be suitably used for manufacturing packages for foods, drugs, etc., and can be particularly suitably used for manufacturing packages for retort foods and simmered foods.

Claims

1. A method for producing a multilayer body comprising a laminate film (A) having at least a base layer (a) and a sealant layer, and a printed film (B) having at least a base layer (b) and a printed layer, comprising: The laminated film (A) and the printed film (B) are laminated by heat fusion, A method for producing a multilayer body, wherein the maximum height (Sz) of the printed layer of the printed film (B) before lamination is 1000 nm or more and 15000 nm or less.

2. 2. The method for producing a multilayer body according to claim 1, wherein the sealant layer of the laminate film (A) and the printed layer of the printed film (B) are laminated by heat fusion.

3. The method for producing a multi-layer body according to claim 1 or 2, wherein the sealant layer contains an epoxy compound and a thermoplastic elastomer.

4. The method for producing a multilayer body according to claim 1 or 2, wherein the printed layer is formed by liquid toner digital printing.

5. The method for producing a multi-layer body according to claim 4 , wherein the liquid toner comprises a polymer having ionic groups.

6. A printed film having at least a base layer and a printing layer, A printed film, wherein the maximum height (Sz) of the printed layer is 1000 nm or more and 15000 nm or less.

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