Stretched film and method for manufacturing stretched film

Abstract

To provide a stretched film which has a large effect for increasing adhesive strength by annealing treatment.SOLUTION: A stretched film contains an adhesive resin composition satisfying requirements (i) to (iii), and a base material layer, and satisfies requirement (I): (i) containing a graft modified body of one or more kinds of base polymers selected from polyolefin by one or more kinds of carbodiimide monomers selected from the group consisting of a compound represented by the following formula (1); (ii) containing 0.1 to 50 mmol of a carbodiimide group per 100 g of the composition; (iii) density of 0.870 to 0.940 g / cm3; and (I) a ratio (A / B) of absorbance (A) of a peak derived from stretching vibration of a carbodiimide group detected by FT-IR analysis of the composition to absorbance (B) of a peak derived from stretching and deformation vibration of polypropylene, before and after heating the stretched film at 100°C for 15 minutes is (A / B before heating)-(A / B after heating)≥0.005. In the formula, R3 is a methyl group, R4 is an alkyl group, and m is an integer of 2 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a stretched film and a method for producing the stretched film. [Background technology]

[0002] Polyolefins such as polyethylene and polypropylene or their modified products are excellent in mechanical strength, rigidity, heat resistance, chemical resistance, oil resistance, transparency, moldability, impact resistance at low temperatures, etc., and are used in a variety of applications by utilizing these properties. For example, modified polyolefins obtained by modifying multi-component polymers having specific compositional ratios have been proposed for use as adhesives (adhesive resin compositions) that have good adhesion to substrates of metal materials such as copper and aluminum, and organic materials such as polyethylene terephthalate (e.g., Patent Document 1).

[0003] When used as an adhesive, molding into a film tends to result in inferior adhesiveness when a molding method with a relatively high molding speed, such as extrusion lamination, is used compared to a molding method with a slow molding speed. Also, stretched films that have been subjected to stretching processing, such as triple bubble inflation, tend to have inferior adhesiveness compared to unstretched films, and there is also a risk of the film shrinking. To solve these problems, the film may be subjected to a heat treatment (annealing treatment) after molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-195498 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in laminated films obtained by laminating adhesive resin compositions having conventional polyolefin-based resins as base polymers, the effect of increasing adhesive strength by annealing treatment is small, and in some cases, stretched films in particular have been insufficient for practical use.

[0006] The present invention has been made in view of the above, and has as its object to provide a stretched film that exhibits a large effect of increasing adhesive strength through annealing treatment. [Means for solving the problem]

[0007] The present invention has the following configuration to achieve the above object. [1] A stretched film comprising an adhesive resin composition satisfying the following requirements (i) to (iii) and a substrate layer, and satisfying the following requirement (I): (i) A graft-modified product of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1):

[0008] [ka] [In formula (1), R3 is a hydrogen atom or a methyl group, R4 is an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more.] (ii) the adhesive resin composition contains 0.1 to 50 mmol of carbodiimide groups per 100 g; (iii) Density is 0.870 to 0.940 g / cm 3 is; (I) The ratio (A / B) of the absorbance (A) of the peak derived from the stretching vibration of the carbodiimide group detected by FT-IR analysis of the adhesive resin composition to the absorbance (B) of the peak derived from the stretching and bending vibration of polypropylene detected by the FT-IR analysis before and after heating the stretched film at 100°C for 15 minutes satisfies the following formula: (A / B before heating) - (A / B after heating) ≥ 0.005

[0009] [2] The stretched film according to [1], wherein the base layer contains at least one resin selected from the group consisting of polyethylene terephthalate, polyphenylene sulfide, modified fluororesin, polyketone, and ABS resin.

[0010] [3] The stretched film according to [1] or [2], wherein the base layer contains polyethylene terephthalate.

[0011] [4] A method for producing a stretched film according to any one of [1] to [3], a molding step of laminating the adhesive resin composition and a substrate layer to form a laminate film; a heat treatment step of heating the laminated film obtained by the molding step; A method for producing a stretched film comprising the steps of:

[0012] [5] The method for producing a stretched film according to [4], wherein the heating temperature in the heat treatment step is 80 to 140°C. [Effects of the Invention]

[0013] According to the present invention, a stretched film can be obtained in which the adhesive strength is significantly increased by annealing. Therefore, the adhesiveness of the stretched film of the present invention is sufficiently increased by annealing, even in stretched films that usually tend to have poor adhesiveness, and the stretched film can have adhesiveness sufficient for practical use. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Stretched film> The stretched film according to the present invention (hereinafter also referred to as "the present stretched film") is characterized by comprising an adhesive resin composition that satisfies predetermined requirements and a substrate layer.

[0015] <Adhesive resin composition> The adhesive resin composition constituting the present stretched film contains at least one base polymer selected from polyolefins graft-modified with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1): The adhesive resin composition may contain one type of graft-modified product or two or more types of graft-modified products.

[0016] [ka] [In formula (1), R3 is a hydrogen atom or a methyl group, R4 is an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more.]

[0017] Graft modified product The graft-modified product is a graft-modified product of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of compounds represented by formula (1), i.e., at least one base polymer selected from polyolefins is graft-modified with at least one carbodiimide monomer selected from the group consisting of compounds represented by formula (1).The graft-modified product can also be said to be a graft-modified product comprising at least one base polymer portion selected from polyolefins and a graft portion derived from at least one carbodiimide monomer selected from the group consisting of compounds represented by formula (1).

[0018] The graft ratio in the graft-modified product is preferably 0.3 to 7% by mass, more preferably 0.5 to 5% by mass, from the viewpoints of ease of synthesis of the graft-modified product, ease of obtaining a graft-modified product having superior compatibility and adhesiveness, and preventing the obtained graft-modified product from becoming too hard. the graft ratio is the mass of the structure derived from the carbodiimide monomer in the graft modified product, 1 It can be determined by H-NMR measurement, specifically by the method described in the examples below.

[0019] <Carbodiimide Monomer> The carbodiimide monomer used when graft-modifying the base polymer is at least one selected from the group consisting of compounds represented by the following formula (1). The carbodiimide monomer used when graft-modifying the base polymer may be of two or more types, but is usually of one type.

[0020] [ka]

[0021] In formula (1), R3 is a hydrogen atom or a methyl group, and a methyl group is preferred from the viewpoint that a graft modified product having excellent adhesive strength to a substrate having a polar group can be easily obtained.

[0022] In formula (1), R4 is an alkyl group or an aryl group which may have a substituent. The alkyl group which may have a substituent may be chain-like (may be linear or branched) or may contain an alicyclic ring.

[0023] The number of carbon atoms in the alkyl group or aryl group which may have a substituent is preferably 1 or more, more preferably 3 or more, and is preferably 20 or less, more preferably 12 or less, and even more preferably 8 or less.

[0024] Examples of the substituent that the alkyl group or aryl group may have include a halogen atom, a hydrocarbon group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a carboxylic acid ester group having 1 to 8 carbon atoms, a sulfonic acid ester group having 1 to 8 carbon atoms, a carbonyl group having 1 to 8 carbon atoms, an amide group having 1 to 8 carbon atoms, an amino group having 1 to 8 carbon atoms, a sulfide group having 1 to 8 carbon atoms, a phosphate ester group having 1 to 8 carbon atoms, an alkylsilyl group having 1 to 8 carbon atoms, and an alkoxysilyl group having 1 to 8 carbon atoms.

[0025] Among these, R4 is preferably a branched, non-cyclic alkyl group, and more preferably a branched, non-cyclic alkyl group having 3 to 7 carbon atoms, from the viewpoint that the present modified product having excellent adhesive strength to a substrate having a polar group, particularly to polyester, can be easily obtained.

[0026] Preferred examples of the branched, non-ring alkyl group include an isopropyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a 1-methylbutyl group, a 1,2-dimethylpropyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1-ethylpropyl group, a 1,1-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-methylpentyl group, a 1,2-dimethylbutyl group, a 1,3-dimethylbutyl group, a 1,2,2-trimethylpropyl group, a 2-methylpentyl group, a 2 ,2-dimethylbutyl group, 2,3-dimethylbutyl group, 2-ethylbutyl group, 3-methylpentyl group, 3,3-dimethylbutyl group, 4-methylpentyl group, 1-ethyl-2-methylpropyl group, 1-ethylbutyl group, 1,1-dimethylbutyl group, 1,1,2-trimethylpropyl group, 1-ethyl-1-methylpropyl group, 1-methylhexyl group, 1,2-dimethylpentyl group, 1,3-dimethylpentyl group, 1,4-dimethylpentyl group, 1,2,3-trimethylbutyl group, 1 ,2,2-trimethylbutyl group, 1,3,3-trimethylbutyl group, 2-methylhexyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 2,3,3-trimethylbutyl group, 1,1-dimethylpentyl group, 1,1,2-trimethylbutyl group, 1,1,3-trimethylbutyl group, 1,1,2,2-tetramethylpropyl group, 2,2-dimethylpentyl group, 2,2,3-trimethylbutyl group, 3-methylhexyl group, 3,4-dimethylpentyl group, 3,3-dimethyl Examples of such groups include a pentyl group, a 1-ethylpentyl group, a 1-ethyl-2-methylbutyl group, a 1-ethyl-3-methylbutyl group, a 1-ethyl-2,2-dimethylpropyl group, a 2-ethylpentyl group, a 2-ethyl-3-methylbutyl group, a 1-ethyl-1-methylbutyl group, a 1-ethyl-1,2-dimethylpropyl group, a 3-ethylpentyl group, a 1,1-diethylpropyl group, a 2,2-diethylpropyl group, a 1-propylbutyl group, a diisopropylmethyl group, and a 1-isopropylbutyl group.

[0027] In formula (1), m is an integer of 2 or more, and from the viewpoints of the solubility of the carbodiimide monomer, ease of availability, ease of purification of the resulting graft-modified product, etc., m is preferably an integer of 2 to 6, more preferably an integer of 2 to 4, and particularly preferably 2.

[0028] <Base polymer> The base polymer before being graft-modified with the carbodiimide monomer is at least one polymer selected from polyolefins, which may include polyolefins obtained from biomass-derived olefins. Specific examples of the olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 4-methyl-1-pentene.

[0029] The polyolefin may be a homopolymer of any of these olefins, a copolymer of two or more of these olefins, or a copolymer of one or more of these olefins with one or more of the following copolymers. Among these, the polyolefin is preferably at least one polymer selected from an ethylene-based polymer, a propylene-based polymer, and a butene-based polymer, and more preferably at least one polymer selected from an ethylene-based polymer and a propylene-based polymer from the viewpoints of excellent solubility in the solvent when a solvent is used during the graft reaction and excellent separability from impurities after the graft reaction. The base polymer may be of two or more types, but is usually of one type.

[0030] In order to more effectively achieve the effects of the present invention, the base polymer is preferably a polymer that does not have at least one active hydrogen-containing group selected from a carboxy group, an acid anhydride group, an amino group, a hydroxy group, and a thiol group. In addition, in order to further exert the effects of the present invention, it is also preferable that the base polymer is a polymer that does not have a carboxylic acid derivative group such as an acid halide, amide, imide, or ester, or a group that is easily converted by water or the like into a group having an active hydrogen, such as an epoxy group.

[0031] The weight average molecular weight (Mw) of the base polymer is not particularly limited, but from the viewpoint of ease of synthesis of the graft modified polymer, it is preferably 100,000 or more, more preferably 150,000 or more, and preferably 1,000,000 or less, more preferably 700,000 or less.

[0032] The number average molecular weight (Mn) of the base polymer is not particularly limited, but for the same reasons, it is preferably 40,000 or more, more preferably 50,000 or more, and preferably 500,000 or less, more preferably 300,000 or less.

[0033] The molecular weight distribution (Mw / Mn) of the base polymer is not particularly limited, but is preferably 1.5 or more, more preferably 2.0 or more, and is preferably 6.0 or less, more preferably 5.0 or less.

[0034] The Mw and Mn values ​​were measured under the following conditions using a gel permeation chromatograph (GPC) model HLC-8321 GPC / HT manufactured by Tosoh Corporation. Separation columns: TSKgel GMH6-HT (2 columns) and TSKgel GMH6-HTL (2 columns) (both 7.5 mm I.D. x 30 cm, manufactured by Tosoh Corporation) Column temperature: 140℃ Mobile phase: o-dichlorobenzene (containing 0.025% dibutylhydroxytoluene (BHT)) Development speed: 1.0mL / min Sample concentration: 0.1% (w / v) Sample injection volume: 0.4 mL Detector: differential refractometer Calibration of the instrument: Monodisperse polystyrene (Tosoh Corporation, #3 standard set) was used.

[0035] The base polymer can be synthesized by a conventionally known method, or a commercially available product may be used. The conventionally known method is not particularly limited, and for example, a method using a coordination polymerization catalyst system containing a transition metal can be mentioned.Specifically, a synthesis method can be mentioned in which ethylene or propylene and, if necessary, a comonomer described below are (co)polymerized in the presence of a catalyst such as a magnesium chloride-supported titanium catalyst, a vanadium catalyst containing a soluble vanadium compound and an alkylaluminum halide compound, or a metallocene catalyst containing a metallocene compound and an organoaluminum oxy compound.

[0036] [Ethylene polymer] The ethylene-based polymer is not particularly limited as long as the content of ethylene-derived structural units in the polymer is 50% by mass or more, and may be an ethylene homopolymer or a copolymer of ethylene and a comonomer. In the case of a copolymer, the structure thereof is not particularly limited.

[0037] The comonomer may be, for example, at least one monomer selected from propylene, α-olefins having 4 to 20 carbon atoms, and conjugated polyenes, and among these, propylene and α-olefins having 4 to 20 carbon atoms are preferred. The α-olefin having 4 to 20 carbon atoms may be linear or branched, and examples thereof include 1-butene, 2-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0038] The content of the comonomer-derived structural units in the ethylene polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoint of preventing blocking of pellets or powder and making them easy to handle, etc. In this specification, an ethylene polymer having a content of propylene-derived or butene-derived structural units of 50% by mass is referred to as an ethylene polymer.

[0039] [Propylene polymer] The propylene polymer is not particularly limited as long as the content of propylene-derived structural units in the polymer is 50% by mass or more, and may be a propylene homopolymer or a copolymer of propylene and a comonomer. The structure of these (co)polymers is not particularly limited.

[0040] The comonomer may be, for example, at least one monomer selected from ethylene, α-olefins having 4 to 20 carbon atoms, and conjugated polyenes, and among these, ethylene and α-olefins having 4 to 20 carbon atoms are preferred. Examples of the α-olefin having 4 to 20 carbon atoms include the same α-olefins having 4 to 20 carbon atoms as those listed in the section on ethylene polymers.

[0041] The content of the comonomer-derived structural units in the propylene polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoints of preventing blocking of pellets or powder and making them easy to handle, etc. In this specification, a propylene polymer having a butene-derived structural unit content of 50% by mass is referred to as a propylene polymer.

[0042] [Butene polymer] The butene polymer is not particularly limited as long as the content of butene-derived structural units in the polymer is 50% by mass or more, and may be a homopolymer of butene, particularly 1-butene, or a copolymer of butene (particularly 1-butene) and a comonomer. The structure of these (co)polymers is not particularly limited.

[0043] The comonomer may be, for example, at least one monomer selected from ethylene, propylene, α-olefins having 5 to 20 carbon atoms, and conjugated polyenes, and among these, ethylene, propylene, and α-olefins having 5 to 20 carbon atoms are preferred. Examples of the α-olefin having 5 to 20 carbon atoms include the same α-olefins having 5 to 20 carbon atoms as those listed in the section on ethylene polymers.

[0044] The content of the structural units derived from the comonomer in the butene polymer is preferably 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoints of preventing blocking of pellets or powder and making them easy to handle.

[0045] <Method for synthesizing graft modified product> The method for synthesizing the graft modified product is not particularly limited as long as a graft modified product can be obtained by graft-modifying the base polymer with the carbodiimide monomer, but from the viewpoint of ease of synthesis of the graft modified product, a method is preferred in which a radical initiator and the carbodiimide monomer are added to a solution in which the base polymer is dissolved or dispersed in a solvent, preferably a solution in which the base polymer is dissolved in an organic solvent, and then reacted (grafted) to cause the reaction. Note that when a reaction apparatus having a stirring capacity capable of uniformly fluidizing the base polymer is used, a solvent may not be used. According to the above method, graft polymerization occurs, and thus a graft modified product is obtained.

[0046] The amount of the carbodiimide monomer used in the graft reaction is preferably 10 to 1,000 mol, more preferably 10 to 800 mol, per mol of the base polymer, from the viewpoints that a graft modified product having a graft rate within the above range can be easily obtained and that the production of a polymer of the carbodiimide monomer itself (hereinafter also referred to as a "non-grafted polymer") can be suppressed.

[0047] Examples of the radical initiator include organic peroxides and azo compounds, and specific examples thereof include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoate)hexyne-3, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(te Examples of the peroxide include organic peroxides such as tert-butylperoxyhexane, tert-butyl perbenzoate, tert-butyl perphenyl acetate, tert-butyl perisobutyrate, tert-butyl per-sec-octoate, tert-butyl perpivalate, cumyl perpivalate, tert-butyl perdiethyl acetate, and tert-butylperoxyisopropyl monocarbonate; and azo compounds such as azobisisobutyronitrile and dimethylazoisobutyrate.

[0048] Among these, organic peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,4-bis(tert-butylperoxyisopropyl)benzene, and tert-butylperoxyisopropyl monocarbonate are preferred. The radical initiators may be used alone or in combination of two or more.

[0049] The amount of the radical initiator used in the graft reaction is preferably 0.01 mol or more, more preferably 0.05 mol or more, and preferably 0.7 mol or less, more preferably 0.5 mol or less, per mol of carbodiimide monomer, from the viewpoints that the graft reaction occurs efficiently and a graft modified product having a graft rate within the above range can be easily obtained.

[0050] The organic solvent is preferably an organic solvent that does not significantly inhibit the grafting reaction of the carbodiimide monomer and has affinity with the base polymer in the temperature range in which the grafting reaction is carried out.Specific examples of such organic solvents include aromatic hydrocarbon solvents such as benzene, toluene, and xylene, aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, and decane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and decahydronaphthalene, chlorinated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, trichlorobenzene, methylene chloride, chloroform, carbon tetrachloride, and tetrachloroethylene, alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate and dimethyl phthalate, and ether solvents such as dimethyl ether, diethyl ether, di-n-amyl ether, tetrahydrofuran, and dioxyanisole.

[0051] Alternatively, suspension polymerization or emulsion polymerization can be carried out using water as a solvent. These solvents may be used alone or in combination of two or more. The use of these solvents preferably makes the reaction liquid a homogeneous phase, but it does not matter if the reaction liquid becomes a heterogeneous multiple phase liquid.

[0052] Since the grafting reaction is carried out in a region where the liquid containing the base polymer can be stirred uniformly, the concentration of the base polymer in the liquid is usually set to 50 to 500 g / L, but to achieve a high grafting rate, it is preferably 200 to 500 g / L.

[0053] The radical initiator and the carbodiimide monomer may be added all at once to a liquid containing the base polymer (or the base polymer itself) to initiate the graft reaction. However, to achieve a high grafting rate, it is preferable to carry out the graft reaction by gradually adding them over a period of about 0.1 to 5 hours.

[0054] When a radical initiator and a carbodiimide monomer are added to a base polymer or a liquid in which the base polymer is dissolved or dispersed in a solvent, the order of addition is not particularly limited. For example, when these are added sequentially as described above, the radical initiator and the carbodiimide monomer may be added sequentially, or the carbodiimide monomer may be added first and then the radical initiator may be added sequentially.

[0055] The grafting reaction is desirably carried out at a temperature of usually 60°C or higher, preferably 100°C or higher, usually 200°C or lower, preferably 160°C or lower, for usually 2 hours or longer, preferably 3 hours or longer, and usually 10 hours or shorter, preferably 8 hours or shorter.

[0056] The graft-modified product obtained by the graft reaction may be purified and isolated by using known methods, such as filtration, centrifugation, reprecipitation and / or washing, in combination as necessary, to remove the solvent used, unreacted radical initiator or carbodiimide monomer, and by-produced non-grafted polymer. In this case, it is desirable to purify and isolate the graft-modified polymer so that the content of non-grafted polymer in the graft-modified polymer is preferably 5% by mass or less, more preferably 2% by mass or less, in order to easily obtain a graft-modified polymer having excellent compatibility and adhesive properties.

[0057] The content of the graft-modified product in the adhesive resin composition is not particularly limited, but from the viewpoints of moldability, controllability of adhesive ability, economic efficiency, etc., it is usually 1 to 100 mass%, preferably 2 to 90 mass%, more preferably 3 to 50 mass%.

[0058] The adhesive resin composition contains 0.1 to 50 mmol, preferably 0.5 to 40 mmol, and more preferably 1 to 30 mmol of carbodiimide groups per 100 g of the adhesive resin composition. The content of carbodiimide groups in the adhesive resin composition can be calculated by the same measurement method as for the graft ratio. When the content of the graft-modified product in the adhesive resin composition is 100 mass %, the graft ratio of the graft-modified product (the mass of the structure derived from the carbodiimide monomer) may be used directly for calculation.

[0059] The density of the adhesive resin composition is 0.870 to 0.940 g / cm 3 and preferably 0.880 to 0.935 g / cm 3 and more preferably 0.890 to 0.930 g / cm 3 The density is a value measured in accordance with JIS K 7112.

[0060] The adhesive resin composition preferably has a melt flow rate (MFR) of 0.1 to 100 g / 10 min, more preferably 1 to 50 g / 10 min, measured at 230°C under a load of 2.16 kg in accordance with JIS K 7210.

[0061] The adhesive resin composition may contain various additives as needed within the range that does not impair the object of the present invention. Examples of the additives include polymers other than the graft modified products, softeners, stabilizers, fillers, antioxidants, crystal nucleating agents, waxes, thickeners, mechanical stability imparting agents, leveling agents, wetting agents, film-forming aids, crosslinking agents, preservatives, rust inhibitors, pigments, dispersants, antifreeze agents, antifoaming agents, tackifiers, other thermoplastic polymers, water, and organic solvents. Each of these may be used alone or in combination of two or more. When a polymer other than the graft modified product is used, it preferably contains the same polyolefin as the base polymer of the graft modified product used.

[0062] ≪Base material layer≫ The base layer constituting the present stretched film preferably contains a polar resin, such as polyethylene terephthalate, polyphenylene sulfide, modified fluororesin, polyketone, ABS resin, polyamide, polyacetal, polycarbonate, poly(meth)acrylate, or biomass plastic. From the viewpoint of adhesion to the adhesive resin composition, the base layer preferably contains one selected from the group consisting of polyethylene terephthalate, polyphenylene sulfide, modified fluororesin, polyketone, and ABS resin, and more preferably contains polyethylene terephthalate.

[0063] When such a substrate layer is used, the carbodiimide groups in the graft-modified polymer react with and bond to the polar groups in the substrate layer, thereby further improving the adhesion between the adhesive resin composition and the substrate layer. In this case, the adhesive resin composition includes not only the graft-modified polymer but also the polymer in which the carbodiimide groups of the graft-modified polymer have reacted with the polar groups in the substrate layer.

[0064] <Physical properties of this stretched film> The present stretched film is not particularly limited as long as it includes a layer made of the adhesive resin composition (hereinafter also referred to as "layer (I)") and a substrate layer (hereinafter also referred to as "layer (II)"), and may include two or more layers (I) or two or more layers (II). When two or more layers (I) are included, these layers may be the same layer or different layers. Similarly, when two or more layers (II) are included, these layers may be the same layer or different layers. The present stretched film is preferably a stretched film containing Layer (I) and Layer (II), or a stretched film containing Layer (II), Layer (I), and Layer (II) in this order.

[0065] The adhesive strength of this stretched film is significantly increased by annealing, so even stretched films, which generally have inferior adhesiveness compared to unstretched films, can be made sufficiently adhesive for practical use by annealing. Annealing also suppresses shrinkage of the stretched film. The present stretched film is not limited to a sheet shape, and may be in any of various known shapes such as hollow containers, cups, trays, etc.

[0066] The thickness of the stretched film is not particularly limited and may be appropriately selected depending on the application of the stretched film, but is preferably 2 μm to 1 mm, more preferably 5 to 700 μm, and even more preferably 10 to 600 μm. The thickness of the layer (I) is not particularly limited and may be appropriately selected depending on the application of the stretched film, but is preferably 1 to 1000 μm. The thickness of the layer (II) is not particularly limited and may be appropriately selected depending on the application of the stretched film, but is preferably 1 to 1000 μm.

[0067] Before and after heating the stretched film at 100°C for 15 minutes, the ratio (A / B) of the absorbance (A) of the peak derived from the stretching vibration of the carbodiimide group detected by FT-IR (infrared spectroscopy) analysis of the adhesive resin composition contained in the stretched film to the absorbance (B) of the peak derived from the stretching and bending vibration of polypropylene detected by the FT-IR analysis satisfies the following formula: (A / B before heating) - (A / B after heating) ≥ 0.005 The ratio (A / B) preferably satisfies the following formula: (A / B before heating) - (A / B after heating) ≥ 0.007 It is more preferable that the following formula is satisfied. (A / B before heating) - (A / B after heating) ≥ 0.01

[0068] The "A / B before heating" refers to the absorbance ratio (A / B) obtained by FT-IR analysis of the adhesive resin composition before heating the stretched film at 100°C for 15 minutes, and the "A / B after heating" refers to the absorbance ratio (A / B) obtained by FT-IR analysis of the adhesive resin composition after heating the stretched film at 100°C for 15 minutes. The difference in the ratio (A / B) before and after heating obtained by the above formula means the degree of disappearance of carbodiimide groups contained in the adhesive resin composition before and after heating, and satisfaction of the above formula indicates that the reaction between the carbodiimide groups and the substrate layer has progressed sufficiently by heating at 100°C for 15 minutes (e.g., heating during annealing treatment). The specific procedure for the FT-IR analysis will be described in detail in the Examples below.

[0069] <<Uses of this stretched film>> The uses of the stretched film are not particularly limited, but because it exhibits good adhesion to the above-mentioned substrate layers, it can be suitably used, for example, as a shrink film or a pouch for various applications, including automobile parts, containers for food or medical use, and packaging materials for food or electronic materials.

[0070] When the present stretched film is used as a shrink film, from the viewpoint of practical use, the peel strength between the substrate layer and the adhesive resin composition is preferably 2.0 N / 15 mm or more, more preferably 3.0 N / 15 mm or more, and even more preferably 5.0 N / 15 mm or more. There is no particular upper limit to the peel strength, but it is usually 100 N / 15 mm or less. The peel strength was measured by the method described in the Examples below.

[0071] <<Method for manufacturing the present stretched film>> The method for producing the stretched film includes (1) a molding step of laminating the adhesive resin composition and a substrate layer to form a laminated film (hereinafter also referred to as "laminated film (1)"), and (2) a heat treatment step of heating the laminated film (1) obtained by the molding step.

[0072] (1) Molding process The molding process for molding the laminated film (1) may be, for example, the following method. (1-1) A method of heat-sealing using a calendar roll molding machine, a press molding machine, or the like at a temperature equal to or higher than the melting temperature of at least one of the preformed layers (I) and (II). (1-2) A method in which a preformed layer (I) or layer (II) is heat-sealed to another layer that is being extruded or calendered. (1-3) When a layer containing a thermoplastic resin is used as the layer (II), the layer (I) and the substrate layer (II) are extruded simultaneously using a multilayer extruder to be heat-sealed (co-extrusion molding). (1-4) When a layer containing a thermoplastic resin is used as the layer (II), a method in which the molten material for forming the layer (I) and the molten material for forming the layer (II) are injected into a mold at different injection times (e.g., two-layer injection molding, sandwich injection molding).

[0073] In the present stretched film manufacturing method, when the layer (I) or layer (II) previously formed by the above methods (1-1) and (1-2) is used, the layer may be stretched before use, or the forming step may include a step of stretching the laminated film (1) obtained by the above methods (1-1) to (1-4). In a stretched film comprising an adhesive resin composition and a substrate layer, the substrate layer generally provides the necessary physical properties for the intended use. Therefore, as long as layer (II) of the stretched film has been subjected to a stretching treatment, layer (I) may be unstretched.

[0074] Since this stretched film contains the adhesive resin composition, for example, when heat-sealed at 200°C, a layer with high adhesive strength can be formed even if the heat-sealing time is short, preferably 20 seconds or less, more preferably 10 seconds or less, and even more preferably 5 seconds or less.

[0075] The method for stretching the layer (I), layer (II), or laminated film is not particularly limited, and examples thereof include stretching using an inflation method, such as a single bubble inflation method, a double bubble inflation method, a triple bubble inflation method, and a tenter method. The stretching ratio is preferably 2.0 to 6.0 times in both the machine direction (MD) and the transverse direction (TD) from the viewpoints of heat shrinkability, good transparency after heat shrinkage, and production stability.

[0076] Furthermore, ionizing radiation may be applied before the stretching. This crosslinks the layer (I) in particular, improving stretchability. The depth of effect of ionizing radiation is generally adjusted by the acceleration voltage. Examples of ionizing radiation include α-rays, β-rays, γ-rays, neutron beams, and electron beams.

[0077] (2) Heat treatment process The heating temperature of the laminated film (1) may be appropriately set depending on the types of adhesive resin composition and substrate, but is preferably a temperature at which the adhesive resin composition and substrate do not deteriorate, more preferably 80 to 140°C, even more preferably 90 to 135°C, and particularly preferably 100 to 130°C. When the heating temperature is within the above range, the thermal shrinkage of the stretched film is also suppressed, and the effect of increasing the adhesive strength between the adhesive resin composition and the substrate layer is sufficiently exhibited.

[0078] The heat treatment time of the laminated film (1) may be appropriately set depending on the types of adhesive resin composition and substrate, but is preferably set to a time that does not cause deterioration of the adhesive resin composition and substrate, more preferably 1 minute to 48 hours, even more preferably 5 minutes to 24 hours, and particularly preferably 10 to 12 hours.

[0079] The adhesive strength between the adhesive resin composition and the substrate of the present stretched film is increased by heat treatment (annealing treatment).Thus, although conventional stretched films generally have inferior adhesiveness compared to unstretched films, the present stretched film can have sufficient adhesiveness by annealing treatment. Furthermore, the effects of the present invention are not limited to stretched films. For example, even in laminated films that are usually considered to have poor adhesive properties, such as non-stretched films and films formed by a forming method with a high forming speed, the adhesive properties can be sufficiently increased by annealing treatment, and it can be expected that they will have excellent adhesive properties. [Example]

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0081] <Method for measuring graft ratio> The grafting rate was measured using a Bruker Biospin AVANCE IIIcryo-500 nuclear magnetic resonance spectrometer (500 MHz) under the following measurement conditions: measurement solvent: 1,1,2,2-tetrachloroethane-d2, measurement temperature: 120°C, spectrum width: 20 ppm, pulse repetition time: 7.0 seconds, pulse width: 5.00 μsec (45° pulse). 1 H-NMR spectrum was measured. In the obtained spectrum, the graft ratio was calculated from the peak intensity ratio of the protons of the hydrocarbon groups bonded to the carbodiimide groups present at 3.0 to 4.0 ppm to the peak intensity ratio of the protons bonded to all hydrocarbon groups originating from the raw polymer present at 0.3 to 2.5 ppm. The content (mmol) of carbodiimide groups was calculated from the graft ratio.

[0082] <Method for measuring density> The density was measured in accordance with JIS K 7112.

[0083] <Method for measuring absorbance> For the laminated films before heating and the heat-treated laminated films produced in the examples and comparative examples, the press sheet (adhesive resin composition) peeled from the base layer (PET sheet) was measured using an FT-IR measurement device (manufactured by JASCO Corporation, FT / IR-4200) in the transmission method at a wave number of 400 cm. -1 ~4000cm -1 , resolution 4cm -1 The infrared absorption spectrum was measured with 32 accumulations. The obtained spectrum showed a peak (2120 cm) due to the stretching vibration of the carbodiimide group (-N=C=N-). -1 The absorbance (A) of the polypropylene stretching and bending vibrations (4320 cm -1 The absorbance (B) at a temperature (around 100°C) was read, and the absorbance ratio (A / B) was calculated from the readout. The absorbance ratio (A / B) obtained from the laminated film before heating produced in the Examples and Comparative Examples was designated "A / B before heating," and the absorbance ratio (A / B) obtained from the heat-treated laminated film was designated "A / B after heating at 100°C for 15 minutes."

[0084] [Manufacturing Example 1] A 500 mL glass vessel was charged with 15.0 g of polypropylene (base polymer, propylene homopolymer, Mw: 313,000, Mn: 70,800, Mw / Mn: 4.43) and 62 mL of xylene, and the atmosphere inside the vessel was replaced with nitrogen. The internal temperature of the vessel was then raised to 120°C, and while maintaining that temperature, 22.1 mmol of ethyl methacrylate-tert-butylcarbodiimide was charged. Next, 9.2 mmol of tert-butylperoxyisopropyl monocarbonate (Perbutyl I, NOF Corporation) dissolved in 10 mL of xylene was added over 10 minutes while stirring at 400 rpm using a double anchor impeller. After stirring for an additional 3 hours, 150 mL of xylene was added to dilute the reaction solution.

[0085] The internal temperature of the vessel was then cooled to 50°C, and the slurry-like reaction liquid was removed. 400 mL of acetone was added to the resulting reaction liquid, which was then stirred for 10 minutes. The stirred liquid was then filtered to separate the solids and the filtrate. The process from adding acetone to the resulting solids to filtering was repeated three more times. The solid content after the fourth filtration was dried in a vacuum dryer at 90°C for 10 hours to obtain 15.37 g of graft polymer (G-1). The graft rate of the obtained graft polymer (G-1) was 1.3 mass% (6.2 mmol / 100 g-(G-1)).

[0086] [Manufacturing Example 2] The same procedure as in Production Example 1 was carried out, except that the amount of polypropylene was changed from 15.0 g to 25.0 g and the amount of maleic anhydride was changed from 22.1 mmol to 33.4 mmol, to obtain 25.01 g of graft polymer (g-1). The graft rate of the obtained graft polymer (g-1) was 0.62 mass% (6.0 mmol / 100 g-(g-1)).

[0087] [Example 1] Preparation of adhesive resin composition Adhesive resin composition (C-1) was obtained by kneading 13 parts by mass of the graft polymer (G-1) produced in Production Example 1 and 87 parts by mass of polypropylene (the same polymer as the base polymer used in Production Example 1) using a Labo Plastomill at a temperature of 190°C, a screw rotation speed of 60 rpm, and a kneading time of 10 minutes. The adhesive resin composition (C-1) had an MFR (230°C, 2.16 kg load) of 4.0 g / 10 min and a density of 0.892 g / cm. 3 The content of carbodiimide groups per 100 g of the composition was 0.8 mmol.

[0088] -Press sheet production The obtained adhesive resin composition (C-1) was press-molded under the conditions of a press plate (upper and lower) temperature of 170°C, a pressure of 4 MPa, a preheating time of 8 minutes, and a pressurizing time of 3 minutes, and then rapidly cooled (cooling time of 3 minutes) in a press molding machine set to 20°C to produce a press sheet with a thickness of 500 μm, a length of 80 mm, and a width of 80 mm.

[0089] -Laminated film production As the base layer, a polyethylene terephthalate (PET) sheet 1 (stretched PET sheet, Lumirror T, manufactured by Toray Industries, Inc., hereinafter also referred to as "PET1") having a thickness of 50 μm, a length of 80 mm and a width of 80 mm was used. A PET sheet, a press sheet and another PET sheet were stacked in that order, and the stack was sandwiched between Teflon (registered trademark) sheets. Heat sealing was performed for 3 or 5 seconds using a heat sealer with the press plate (top and bottom) temperature set to 200°C and the pressure set to 0.15 MPa to produce a three-layer laminated film.

[0090] - Preparation of heat-treated laminated film The resulting laminated film was placed in an oven preheated to 100°C and heat-treated for 15 minutes, then removed from the oven and allowed to stand at room temperature (23°C) for 1 hour to produce a heat-treated laminated film.

[0091] Adhesion evaluation (peel test) For each of the prepared laminate films before heat treatment and the heat-treated laminate films, the peel strength between the upper PET sheet (the PET sheet on the (upper) side of the press plate) and the press sheet was measured by T-peeling under conditions of a peeling atmosphere temperature of 23°C, a peeling speed of 300 mm / min, and a peel width of 15 mm. The results are shown in Table 1. Note that because the adhesive strength is strong, cases where the PET sheet itself, rather than the interface between the PET sheet and the press sheet, was torn are referred to as "PET resin tearing."

[0092] [Reference example 1] A laminated film and a heat-laminated film were produced in the same manner as in Example 1, except that the PET sheet 1 used in the preparation of the press sheet in Example 1 was replaced with PET sheet 2 (unstretched PET film, Mitsui PET "J005PC", manufactured by Mitsui Chemicals, Inc., hereinafter also referred to as "PET2"), and adhesion evaluation was performed. The results are shown in Table 1.

[0093] [Comparative Example 1] An adhesive resin composition (C-2) was obtained in the same manner as in Example 1, except that 13 parts by mass of the graft polymer (g-1) produced in Production Example 2 and 87 parts by mass of polypropylene (the same polymer as the base polymer used in Production Example 1) were used. The adhesive resin composition (C-2) obtained had an MFR (230°C, 2.16 kg load) of 3.1 g / 10 min and a density of 0.892 g / cm 3 The amount of maleic anhydride groups per 100 g of the composition was 0.8 mmol, and the composition did not contain any graft-modified product with a carbodiimide monomer. Thereafter, a laminated film and a heat-laminated film were prepared in the same manner as in Reference Example 1, and adhesion evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0094] Comparative Example 2 Ethylene-glycidyl methacrylate copolymer (Lotader "AX8840", Arkema, density 0.940 g / cm 3 ) was used as is without compounding, a laminated film and a heat-treated laminated film were produced in the same manner as in Reference Example 1, and adhesion evaluation was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0095] [Table 1]

[0096] As shown in Table 1 above, the stretched film (Example 1) using the adhesive resin composition of the present invention showed an increase in peel strength (adhesion strength) by annealing, even when a stretched PET film was used as the substrate layer, resulting in sufficient adhesion for practical use. Furthermore, Reference Example 1, which used the adhesive resin composition of the present invention and a non-stretched PET film as the substrate layer, also showed an increase in adhesive strength by annealing, similar to Example 1. On the other hand, the laminated films of Comparative Examples 1 and 2 showed almost no increase in adhesive strength by annealing. From the relationship between Reference Example 1 and Example 1, it is presumed that even if the non-stretched PET film used as the substrate layer in Comparative Examples 1 and 2 were replaced with a stretched PET film, no increase in adhesive strength by annealing would be observed, and sufficient adhesiveness would not be obtained.

Claims

1. A stretched film comprising an adhesive resin composition satisfying the following requirements (i) to (iii) and a substrate layer, and satisfying the following requirement (I): (i) A graft-modified product of at least one base polymer selected from polyolefins with at least one carbodiimide monomer selected from the group consisting of compounds represented by the following formula (1): 【Chemical 1】 [In formula (1), R 3 is a hydrogen atom or a methyl group, and R 4 represents an alkyl group or an aryl group which may have a substituent, and m is an integer of 2 or more. (ii) the adhesive resin composition contains 0.1 to 50 mmol of carbodiimide groups per 100 g; (iii) Density is 0.870 to 0.940 g / cm 3 is; (I) The ratio (A / B) of the absorbance (A) of the peak derived from the stretching vibration of the carbodiimide group detected by FT-IR analysis of the adhesive resin composition to the absorbance (B) of the peak derived from the stretching and bending vibration of polypropylene detected by the FT-IR analysis before and after heating the stretched film at 100°C for 15 minutes satisfies the following formula: (A / B before heating)−(A / B after heating)≧0.005

2. 2. The stretched film according to claim 1, wherein the base layer comprises at least one resin selected from the group consisting of polyethylene terephthalate, polyphenylene sulfide, modified fluororesin, polyketone, and ABS resin.

3. The stretched film of claim 1 , wherein the substrate layer comprises polyethylene terephthalate.

4. A method for producing the stretched film according to any one of claims 1 to 3, a molding step of laminating the adhesive resin composition and a substrate layer to form a laminate film; a heat treatment step of heating the laminated film obtained by the molding step; A method for producing a stretched film comprising the steps of:

5. The method for producing a stretched film according to claim 4, wherein the heating temperature in the heat treatment step is 80 to 140°C.

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