[Technical Field]

[0001] The present invention relates to a metallized film comprising a polypropylene layer and a metallized layer comprising a metal or a metal oxide and disposed on the polypropylene layer, the film being high in bonding strength, that is, adhesion between the polypropylene layer and the metallized layer.

[Background Art]

[0002] Polypropylene films have been used widely in the field of packaging, and for the purpose of imparting gas barrier characteristics or light barrier characteristics to said films, there have been used metallized films in which metal or metal oxide is vapor-deposited on said films.

[0003] For example, Patent Document 1 discloses a packaging film intending to improve adhesion to vacuum vapor deposited aluminum, the film including a first layer comprising a metal film and a second layer comprising a polymer composition comprising a blend of an alkene polymer with a modifier selected from the group consisting of maleic anhydride-grafted ethylene copolymers, ethylene copolymers containing acid monomers and/or ester monomers, acid-grafted propylene copolymers, and maleic anhydride-grafted blends of propylene copolymers with ethylene copolymers.

[0004] Patent Document 2 discloses a polymer film comprising 00 parts by weight of a polyolefin resin, 1 to 5 parts by weight of a cross-linking agent and 1 to 5 parts by weight of a silane coupling agent, characterised in that the film contains holes with a size of 50 pm or more and at a density of 10 holes per metre ² or less.

[0005] The listing or discussion of a prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

[Patent Document 1 ] WO 2005/066266

[Patent Document 2] JP 2010275415

[Summary of the Invention]

[Problems to Be Solved by the Invention]

[0006] However, the packaging film disclosed in Patent Document 1 is not yet satisfactory in adhesion between the layer comprising the metal film and the layer comprising the alkene polymer. Further, in order to provide a film that is of acceptable quality, the metallized film must maintain good optical properties.

[0007] Under such a background art, the object of the present invention is to provide a metallized film comprising a polypropylene layer and a metallized layer comprising a metal or a metal oxide and disposed on the polypropylene layer, the film being high in bonding strength, that is, adhesion between the polypropylene layer and the metallized layer.

[0008] Namely, the present invention relates to a metallized film comprising a polypropylene layer comprising a polypropylene and 0.01 parts by weight to 1 part by weight of a silane coupling agent per 100 parts by weight of the polypropylene, and a metallized layer comprising a metal or a metal oxide and disposed on the polypropylene layer.

[0009] Thus, a first aspect of the invention relates to a metallized film, as set out in claim 1 below. Embodiments of this aspect are disclosed in claims 2 to 42 below.

[0010] Further, a second aspect of the invention relates to a polymer composition, as set out in claim 43 below. Embodiments of this aspect are set out in claims 44 to 72 below. [Advantageous Effects of the Invention]

[0011] According to the present invention, a metallized polypropylene film high in the bonding strength of a metallized layer, that is, the adhesion between a polypropylene layer and a metallized layer, can be obtained.

[Mode for carrying out the invention]

[0012] The polypropylene to be used for the present invention includes propylene homopolymers composed of structural units derived from propylene, and propylene copolymers comprising structural units derived from at least one sort of olefin selected from-among ethylene and a-olefins having 4 to 12 carbon atoms and structural units derived from propylene. Examples of the propylene copolymers include propylene-ethylene random copolymers, propylene-a-olefin random copolymers, and propylene-ethylene-a-olefin random copolymers.

[0013] Examples of the a-olefin having 4 to 12 carbon atoms include -butene,

2- methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene,

3- methyl-1 -pentene, 4-methyl-1 -pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1 -pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1 -pentene, ethyl-1 -hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1 -pentene, propyl-1 -pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. -Butene, 1-pentene, 1-hexene, and 1-octene are preferable, and 1-butene is more preferable in terms of its good copolymerizability and availability at a low price.

[0014] Examples of the propylene-a-olefin random copolymer include a propylene-1-butene random copolymer and a propylene-1 -hexene random copolymer, and a propylene-1 -butene random copolymer is preferable. [0015] Examples of the propylene-ethylene-a-oiefin random copolymer include a propylene-ethylene-1-butene random copolymer and a propylene-ethylene-1 -hexene random copolymer, and a propylene-ethylene-1 -butene random copolymer is preferable.

[0016] When the polypropylene is a propylene copolymer comprising structural units derived from propylene and structural units derived from ethylene, the content of the structural units derived from ethylene contained in the copolymer is usually 0.1 % by weight to 10% by weight, preferably 1 % by weight to 5% by weight, and more preferably 1.5% by weight to 3% by weight, where the whole quantity of the copolymer is taken as 00% by weight.

[0017] When the polypropylene is a propylene copolymer comprising structural units derived from propylene and structural units derived from an oc-olefin having 4 to 12 carbon atoms, the content of the structural units derived from the oc-olefin having 4 to 12 carbon atoms contained in the copolymer is usually 0.1 % by weight to 20% by weight, preferably 5% by weight to 15% by weight, and more preferably 8% by weight to 12% by weight, where the whole quantity of the copolymer is taken as 100% by weight.

[00 8] In terms of flowability and film formability, the melt flow rate (henceforth referred to as MFR) of the polypropylene measured at a temperature of 230°C and a load 21.18N is. preferably 0.1 g/10 minutes to 20 g/10- minutes, and more preferably 1 g/10 minutes to 10 g/10 minutes.

[0019] The polypropylene to be used for the present invention is produced by a conventional polymerization method using a conventional catalyst. Examples of the conventional catalyst include (1 ) a catalyst comprising a solid catalyst component obtained by reacting a magnesium compound with a titanium compound, and an organoaluminum compound, (2) a catalyst comprising a solid catalyst component obtained by reacting a magnesium compound with a titanium compound, an organoaluminum compound, and a third component such as an electron donating compound, and (3) a metallocene based catalyst. Preferred is the above-mentioned (2), specifically, a catalyst comprising a solid catalyst component comprising magnesium, titanium, and halogen as essential components, an organoaluminum compound, and an electron donating compound, and examples of this type of catalyst include the catalysts disclosed in JP 61-218606 A, JP 61-287904 A, or JP 7-2160 7 A.

[0020] Examples of the conventional polymerization method include slurry polymerization and solvent polymerization each using an inactive hydrocarbon solvent, liquid phase polymerization using a monomer as a solvent without using any inactive hydrocarbon solvent, gas phase polymerization, or liquid phase-gas phase polymerization in which liquid phase polymerization and gas phase polymerization are conducted continuously. Gas phase polymerization is preferable. In the production of the polypropylene, a polypropylene formed as a result of polymerization may be heated under reduced pressure at a temperature lower than the temperature at which the polypropylene melts, in order to remove the remaining solvent, oligomers generated as by-products during the production. Examples of the method of heating under reduced pressure include the methods of drying under reduced pressure disclosed in JP 55-75410 A and JP 2-80433 A.

[0021] The silane coupling agent to be used for the present invention is a compound being composed of a structure originating in an organic compound and a silicon compound and having at least two kinds of functional groups. Examples of such functional groups include a hydrolyzable functional group and a reactive functional group. Examples of the hydrolyzable functional group include a methoxy group, an ethoxy group, and a (methoxy)methoxy group, and examples of the reactive functional group include an amino group, an epoxy group, a vinyl group, a (l-methyl)vinyl group, and a mercapto group.

[0022] Examples of the silane coupling agent to be used for the present invention include monoalkoxysilanes, dialkoxysilanes, and trialkoxysilanes, and trialkoxysilanes are preferable. Further examples are (1 ) amino group-containing silanes, (2) ethylenically unsaturated bond group-containing silanes, (3) mercapto group-containing silanes, (4) carboxyl group-containing silanes, and (5) epoxy group-containing silanes.

Preferred are (1) amino group-containing silanes and (2) ethylenically unsaturated bond group-containing silanes.

[0023] Preferably, (1 ) the amino group-containing silane is an amino group-containing alkoxysilane. More preferred are the following silanes (1 -1 ) or silanes (1-2).

(1-1 ) (Aminoalkyl)alkoxysilanes, wherein the aminoalkyl is an aminoalkyl group having 2 to 4 carbon atoms, and the alkoxy is an alkoxy group having 1 to 4 carbon atoms.

(1-2) (N-(Aminoalkyl)aminoalkyl)trialkoxysilanes, wherein the N-(aminoalkyl)amino is an amino group having an aminoalkyl group having 1 to 4 carbon atoms; the aminoalkyl having the amino group is an aminoalkyl group having 1 to 4 carbon atoms; and the alkoxy is an alkoxy group having 1 to 4 carbon atoms.

[0024] Examples of the silanes (1-1) include aminomethyltriethoxysilane,

2- aminoethyltrimethoxysilane, 1 -aminoethyltrimethoxysilane,

3- aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropylmethyldimethoxysilane.

[0025] Examples of the silanes (1-2) include N-aminomethylaminomethyltrimetoxysilane,

3-(N-aminomethylamino)propyltrimethoxysilane, and 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane.

[0026] Preferably, (2) the ethylenically unsaturated bond group-containing silanes are (2-1 ) (vinyl)alkoxysilanes, (2-2) (acryloxy)alkylsilanes, or (2-3) (methacryloxy)alkylsilanes.

[0027] More preferably, (2-1) the (vinyl)alkoxysilanes are vinyltrialkoxysilanes, wherein the alkoxy is an alkoxy group having 1 to 4 carbon atoms, and examples thereof include vinyltrimethoxysilane.

[0028] More preferably, (2-2) the (acryloxy)alkylsilanes are acryloxyalkylalkoxysilanes, wherein the acryloxyalkyl is an alkyl group having 2 to 4 carbon atoms and having an acryloxy group and the alkoxy is an alkoxy group having 1 to 4 carbon atoms, and examples thereof include 3-acryloxypropyltrimethoxysilane, 2-acryloxyethyltrimethoxysilane, and 3-acryloxypropylmethyldimethoxysilane.

[0029] More preferably, (2-3) the (methacryloxy)alkylsilanes are methacryloxyalkylalkoxysilanes, wherein the methacryloxyalkyl is an alkyl group having 2 to 4 carbon atoms and having an methacryloxy group and the alkoxy is an alkoxy group having 1 to 4 carbon atoms, and examples thereof include 3-methacryloxypropyltrimethoxysilane, 2-methacryloxyethyltrimethoxysilane, and 3-methaciyloxypropylmethyldimethoxysilane.

[0030] Preferably, (3) the mercapto group-containing silanes are mercapto group-containing alkoxysilanes. More preferred are mercaptoalkyltrialkoxysilanes, wherein the mercaptoalkyl is an alkyl group having 2 to 4 carbon atoms and having a mercapto group and the alkoxy is an alkoxy group having 1 to 4 carbon atoms, and examples thereof include 3-mercaptopropyltrimethoxysilane.

[0031] Preferably, (4) the carboxyl group-containing silanes are carboxyl group-containing alkoxysilanes. More preferred are carboxyalkyltriaikoxysilanes, wherein the carboxyalkyi is an alkyl group having 2 to 4 carbon atoms and having a carboxy group and the alkoxy is an alkoxy group having 1 to 4 carbon atoms, and examples thereof include 2-carboxyethyltrimethoxysilane.

[0032] Preferably, (5) the epoxy group-containing silanes are epoxy group-containing alkoxysilanes. More preferable are the following silanes (5-1 ), silanes (5-2), or silanes (5-3).

(5-1 ) Alkyltrialkoxysilanes has an alicyclic epoxy group, wherein the alkyl having an alicyclic epoxy group is an alkyl group having 1 to 4 carbon atoms and having an alicyclic epoxy group, and the alkoxy is an alkoxy group having 1 to 4 carbon atoms.

(5-2) Glycidyloxyalkyltrialkoxysilanes, wherein the glycidyloxyalkyl is an alkyl group having 1 to 4 carbon atoms and having a glycidyloxy group.

(5-3) (Glycidyloxyalkoxy)alkylalkoxysilanes, wherein the glycidyloxyalkoxy is an alkoxy group having to 4 carbon atoms and having a glycidyloxy group; the

(glycidyloxyalkoxy)alkyl is an alkyl group having 1 to 4 carbon atoms and having a glycidyloxyalkoxy group; the alkoxy is an alkoxy group having 1 to 4 carbon atoms.

[0033] Examples of the silanes (5-1) include

3,4-epoxycyclohexylmethyltripropoxy silane,

2- (3,4-epoxycyclohexyl)ethyltrimethoxysilane, and

3- (3,4-epoxycyclohexyl)propyltrimethoxysilane.

[0034] Examples of the silanes (5-2) include glycidyloxymethyltrimetoxysilane, 2- glycidyloxyethyltrimethoxysilane, 3-glycidyloxypropyl trimethoxysilane, and

3- glycidyloxypropyltributoxysilane.

[0035] Examples of the silanes (5-3) include

3-(2-glycidyloxyethoxy)propyltrimethoxysilane.

[0036] The content of the silane coupling agent to be used for the present invention is 0.01 parts by weight to 1 part by weight per 00 parts by weight of the polypropylene contained in the polypropylene layer. The content is preferably 0.1 parts by weight to 0.5 parts by weight. Adjusting the content of the silane coupling agent to 0.01 parts by weight to 1 part by weight allows the bonding strength of a metallized film to be improved without deteriorating the gloss, etc. of a polypropylene layer.

[0037] The polypropylene layer of the present invention may contain additives other than the silane coupling agent and resins other than the polypropylene. Examples of the additives include antioxidants, UV absorbers, antistatic agents, lubricants, nucleating agents, anticlouding agents, and antiblocking agents.

[0038] Antioxidants are compounds which have an action to prevent the polypropylene layer of the present invention or the polypropylene to be used for the polypropylene layer from being decomposed by heat, light, oxygen, or the like. Examples thereof include phenolic antioxidants, phosphorus-containing antioxidants, sulfur-containing antioxidants, and hydroxylamine-based antioxidants, and preferable are phenolic antioxidants, phosphorus-containing antioxidants, and sulfur-containing antioxidants.

[0039] Examples of the phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol, tetrakis[methylene-3-(3',5'-di-tert-butyl-4- hydroxyphenyl)propionate]methane, octadecyl 3-(3,5-di-tert-butyl-4-hydroxy- phenyl)-propionate, 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)- propionyloxy}-1 .l-dimethylethyl^AS.I O-tetraoxaspirofS'SJundecane, 1 ,3,5-tris- 2[3(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethylisoc yanate, 1 ,3,5-tri- methyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(3,5-di-tert-butyl- 4-hydroxybenzyl)isocyanurate, 1 ,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethyl- benzyl)isocyanurate, pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxy- phenyl)propionate], triethylene glycol-N-bis-3-(3-tert-butyl-5-methyl-4- hydroxyphenyl)propionate, 1 ,6-hexanediol bis[(3-(3,5-di-tert-butyl-4-hydroxy- phenyl)propionate)], 2,2-thiobis-diethylenebis[(3-(3,5-di-tert-butyl-4-hydroxy- phenyl)propionate)], 2,2 ^, -methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis-(4,6-di-tert- butylphenol), 2,2'-ethylidene-bis-(4,6-di-tert-butylphenol), 2,2 -butylidene- bis-(4-methyl-6-tert-butylphenol), 4,4 ^, -butylidenebis(3-methyl-6-tert-butylphenol), 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-met hylphenyl acrylate, and 2,4-di-tert-amyl-6-(1 -(3,5-di-tert-amyl-2-hydroxyphenyl)ethyl)phenyl acrylate. - ^J [0040] Further examples include tocopherols, especially, vitamin E, which is a-tocopherol.

[0041] Preferable are 2,6-di-tert-butyl-4-methylphenol, tetrakis[methylene- SiS'.S'-di-tert-butyl^-hydroxyphenylJpropionatelmethane, 2,6-di-tert-butyl-4- methylphenol, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propiony loxy}-1 , 1 -dimethyl ethyl]-2,4,8,10-tetraoxaspiro[5*5]undecane, tris(3,5-di-tert-butyl-4-hydroxy- benzyl)isocyanurate, and vitamin E, and more preferable are tetrakis[methylene-3(3',5'-di-tert-butyl-4-hydroxyphenyl)-pr opionate]methane, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and vitamin E.

[0042] The content of a phenolic antioxidant is generally 0.01 parts by weight to 2 parts by weight, preferably 0.01 parts by weight to 1 part by weight, and more preferably 0.01 parts by weight to 0.5 parts by weight per 100 parts by weight of the polypropylene.

[0043] Examples of the phosphorus-containing antioxidants include tris(nonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2,4-dicumylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4 ^, -diphenylene diphosphonite, 2,2'-methylenebis(4,6-di-tert-butylphenyl) 2-ethylhexylphosphite, 2,2'-ethylidenebis(4,6-di-tert-butylphenyl) fluorophosphite, bis(2,4-di-tert-butyl-6-methy!phenyl)ethylphosphite,

2-(2,4,6-tri-tert-butylphenyl)-5-ethyl-5-butyl-1 ,3,2-oxaphosphorinane,

2 _> 2 ^, _I 2"-nitrilo[triethyltris(3 _I 3 ^, ,5,5 ^, -tetra-tert-butyM ,1 '-biphenyl-2,2'-diyl) phosphite, and 2,4,8, 10-tetra-tert-butyl-6-[3-(3-methyl-4-hydroxy-5-tert-butylphe nyl)- propoxy]dibenzo[d,fJ[1 ,3,2]dioxaphosphepin. Preferable are tris(2,4-di-tert-butylphenyl) phosphite and 2,4,8, 10-tetra-tert-butyl-6-[3-(3- methyl-4-hydroxy-5-tert-butylphenyl)propoxy]dibenzo[d,f][1 ,3,2]- dioxaphosphepin.

[0044] The loading of a phosphorus-containing antioxidant is generally 0.01 parts by weight to 2 parts by weight, preferably 0.01 parts by weight to 1 part by weight, and more preferably 0.01 parts by weight to 0.5 parts by weight per 100 parts by weight of the polypropylene.

[0045] Examples of the sulfur-containing antioxidant include dilauryl 3,3 -thiodipropionate, tridecyl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, lauryl stearyl 3,3'-thiodipropionate, neopentanetetrayltetrakis(3-laurylthiopropionate), bis[2-methyl-4-(3-dodecylthiopropionyloxy)-5-tert-butylpheny l]sulfide,

bis[2-methyl-4-(3-tridecylthiopropionyloxy)-5-tert-butylp henyl]sulfide, and bis[2-methyl-4-(3-tetradecylthiopropionyloxy)-5-tert-butylph enyl]sulfide.

Preferable are dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate.

[0046] The loading of a sulfur-containing antioxidant is generally 0.01 parts by weight to 2 parts by weight per 00 parts by weight of the polypropylene. The loading is preferably 0.01 parts by weight to 1 part by weight, and more preferably 0.01 parts by weight to 0.5 parts by weight.

[0047] For the avoidance of doubt, further resins, other than ones containing polypropylene, may be added to the polypropylene layer to form a blend. Examples of said resins other than the polypropylene include olefin-based resins such as polyethylene and polybutene, and copolymer elastomers made up of ethylene and an ct-olefin; these may be either products produced using homogeneous catalysts or products produced using heterogeneous catalysts, such as metallocene based catalysts. Further examples include styrene-based copolymer rubbers produced by hydrogenating styrene-butadiene-styrene copolymers or styrene-isoprene-styrene copolymers.

[0048] A particularly preferred polypropylene layer is one where a polypropylene polymer, as discussed herein, is blended with a high-density polyethelene polymer. When the polypropylene layer of the metallized polypropylene film of the present invention contains a polypropylene and a high density polyethylene, their contents are 90 parts by weight to 99.9 parts by weight of the polypropylene and 0.1 parts by weight to 10 parts by weight of the high density polyethylene, where the total of the weights of the polypropylene and the high density polyethylene are taken as 100 parts by weight, and preferably 93 parts by weight to 99 parts by weight of the polypropylene and 1 part by weight to 7 parts by weight of the high density polyethylene.

[0049] The density of the high density polyethylene is preferably 0.93 g/cm ³ to 0.98 g/cm ³ , more preferably 0.95 cm3 to 0.97 g/cm ³ .

[0050] The MFR of the high density polyethylene measured at 190°C and 2 . 8 N is preferably 1 g/10 minutes to 100 g/10 minutes, more preferably 1 g/10 minutes to 50 g/10 minutes.

[0051] To the polypropylene, the high density polyethylene, or the resin composition of a polypropylene and a high density polyethylene to be contained in the polypropylene layer to be used for the present invention may be added an additive or an additional resin, as required. Examples of the additives include antioxidants, UV absorbers, antistatic agents, lubricants, nucleating agents, anticlouding agents, antiblocking agents, and metal deactivators. Examples of which are disclosed herein or are conventionally known.

[0052] The method for producing the resin composition to be used for the present invention comprising the polypropylene and the silane coupling agent may be a method involving melt-kneading the polypropylene and the silane coupling agent together by using a single screw extruder or a twin screw extruder. In the event that the resin composition further comprises other additives or other resins, a method involving melt-kneading the polypropylene and the silane coupling agent together with such an additive or such an additional resin may be employed.

[0053] The metallized film of the present invention is a metallized film comprising a polypropylene layer and a metallized layer. Said metallized layer is a deposited layer containing a metal element and is a layer formed by vapor deposition of a metal or a metal oxide on said polypropylene layer. Therefore, trie metallized layer is composed of a metal or a metal oxide. The polypropylene layer may have said metallized layer only on one side thereof or alternatively may have said metallized layer on both sides.

[0054] The metallized film of the present invention can be produced by vapor-depositing a metal or a metal oxide onto a base film made of a resin composition comprising a polypropylene and a silane coupling agent. The base film can be produced by a method of producing a film from a resin composition to be used for the present invention comprising a polypropylene and a silane coupling agent by using a conventional film forming method such as a blown film forming method, a T-die method, and a calendering method.

[0055] Said base film prior to being subjected to vapor-deposition of a metal or a metal oxide may have been drawn. A drawn base film can be produced by drawing a film or a sheet prepared by forming a resin composition to be used for the present invention comprising a polypropylene and a silane coupling agent. Examples of methods for the drawing include methods involving uniaxially or biaxially drawing films by a roll drawing process, a tenter drawing process, a tubular drawing process, or the like. Before the vapor-deposition of a metal or a metal oxide, surface treatment, such as corona discharge treatment, plasma treatment, and flame treatment, may be applied to the base film on its surface on which a metal or a metal oxide is to be vapor-deposited. Corona treatment is preferred.

[0056] The thickness of the base film onto which a metal or a metal oxide is to be vapor-deposited and the thickness of the polypropylene layer in the metallized film of the present invention is 1 μπι to 500 μιη, more preferably 5 μιη ίο ΙΟΟ μηι.

[0057] The method for vapor-depositing a metal or a metal oxide may be, for example, a method in which a base film to form a polypropylene layer is placed under a high vacuum, and metal vapor or metal oxide vapor is introduced and thereby a metal or a metal oxide is deposited onto the base film.

[0058] Examples of the metal to vapor-deposit include aluminum, titanium, chromium, nickel, copper, germanium, tin, and selenium, and examples of the metal oxide include silica and aluminum oxide. Preferable is aluminum, silica, or aluminum oxide.

[0059] The thickness of the metallized layer is usually 100 A to 1000 A, preferably 300 A to 700 A.

[0060] In one embodiment, the metallized film of the present invention is a metallized film that further comprises a substrate layer in addition to said polypropylene layer and said metallized layer. In the metallized film of this embodiment, the substrate layer has been disposed on a side of the polypropylene layer opposite from the side on which the metallized layer has been formed. The metallized film of this embodiment can be produced by vapor-depositing a metal or a metal oxide onto an exposed surface of a base film composed of a polypropylene layer and a substrate layer laminated together. The method for depositing a metal or a metal oxide may be the above-described one.

[0061] Said base film in which a polypropylene layer and a substrate layer are laminated can be produced by applying a method for producing a multilayer body commonly known. For example, when the substrate layer is made of a resin, there can be used a method involving layering a melt of the resin composition to be used for the present invention comprising a polypropylene and a silane coupling agent and a melt of the resin to be used for the substrate layer by using a co-extrusion process, or a method involving laminating a film prepared by forming the resin composition to be used for the present invention comprising a polypropylene and a silane coupling agent and a film prepared by forming the resin to be used for the substrate layer by an extrusion laminating process, a heat laminating process, or a dry laminating process.

[0062] Said laminated base film to be used for the production of a metallized film of this embodiment may have been drawn by the afore-mentioned drawing method.

[0063] Before the vapor-deposition of a metal or a metal oxide, surface treatment, such as corona discharge treatment, plasma treatment, and flame treatment, may be applied to the base film on its exposed surface of the polypropylene layer on which surface a metallized layer is to be formed by vapor-depositing a metal or a metal oxide.

Corona treatment is preferred.

[0064] In the metallized film of this embodiment, the thickness of the polypropylene layer is 1 μιη to 500 μηι, and preferably 3 to 100 μιτι. The thickness of the substrate layer is 5 μηη to 500 μητι, and preferably 5 μητι to 100 μητι. The thickness of the metallized layer is usually 100 A to 1000 A, preferably 300 A to 700 A.

[EXAMPLES]

[0065] The present invention is illustrated by the following Examples and Comparative Examples. The measured values of the respective items in the detailed description of the invention, the Examples, and the Comparative Examples were measured by the methods described below. [0066]

(1) The content of structural units derived from ethylene contained in polypropylene and the content of structural units derived from 1-butene (unit: % by weight, where the whole weight of the polypropylene is taken as 100% by weight)

The content of structural units derived from ethylene was determined in accordance with the method relating to (i) random copolymers described in Ivlacromolecule Handbook, page 616 (published by Kinokuniya Co., Ltd., 1995) after IR spectrum measurement. The content of structural units derived from 1-butene was determined in accordance with the method relating to (i) random copolymers described in Ivlacromolecule Handbook, page 619 (published by Kinokuniya Co., Ltd., 1995) after IR spectrum measurement.

[0067]

(2) Melting Temperature (Tm, unit: °C)

Using a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer, Inc.), a specimen of about 10 mg was heated under nitrogen atmosphere up to 220°C at a temperature ramp-up rate of 220°C/min, holding the sample at 220°C for 5 minutes, thereby melting it, and then cooling it down to 87°C at a temperature ramp-down rate of 200°C/min. After holding at 87°C for 5 minutes, the temperature was raised up to 220°C at a temperature ramp-up rate of 5°C/min and a fusion endothermic curve was produced. The temperature of the maximum peak of the fusion endothermic curve was defined as a melting temperature (henceforth indicated by Tm). The melting point of indium (In) measured at a temperature ramp-up rate of 5°C using this measurement method Was 156.6°C.

[0068] 0589

(3) Melt flow rate (MFR; unit: g/10 min)

The MFR of a polypropylene was measured by at a temperature of 230°C and a load of 21.18 N in accordance with JIS K7210.

The MFR of a high density polyethylene was measured by at a temperature of 190°C and a load of 2 .18 N in accordance with JIS K7210.

[0069]

(4) The content of components soluble in 20°C xylene (CXS, unit: % by weight)

A sample of 0.5 g was dissolved completely in 50 mL of boiling xylene, and then cooled to room temperature and left at rest for 30 minutes and then it was cooled to 20°C for 90 minutes. Subsequently, the resultant was separated into precipitates and a solution by filtration, and the filtrate was dried up at 70°C under reduced pressure, affording a residue. The residue was weighed and then the content of components soluble in 20°C xylene (henceforth called CXS) was calculated.

[0070]

(5) Gloss (unit: %)

Gloss was measured in accordance with JIS K7105.

[0071]

(6) Anti-blocking (unit: N/m ² )

Two film samples of 225 mm in the longitudinal direction (MD) and 50 mm in the transverse direction (TD) were superimposed on their measurement surfaces, followed by thermal treatment in an oven of 80°C for 3 hours under a load of 15 kg on a loading area sized 100 mm in MD and 50 mm in TD. Subsequently, the sample was left at rest at a room temperature of 23°C in an atmosphere with a humidity of 50% for 30 minutes of more, and then a top and bottom release force was measured at a rate of 20 gf/min. For the measurement was used an top and bottom blocking analyzer (Instron Table

Mounted Universal Tensile Tester Model 5542).

[0072]

(7) Bonding strength (unit: N/15 mm)

An undrawn film on which a metal was vapor-deposited was heat-sealed on its metal-deposited surface with an ethylene-vinyl acetate copolymer (EVA) film of 50 μηι in thickness at a temperature of 125°C and a pressure of 2 kg/cm ² for 2 seconds. In the heat-sealing, cellophane was inserted to between the EVA film and a sealing bar in order to prevent the EVA film from sticking to the sealing bar. After the heat-sealing, the resulting laminate was pressed 10 times with a roller of 2 kg in order to secure sufficient adhesion strength between the EVA film and the metal-deposited surface. The resulting laminate film was conditioned at 110°C for 2 hours, and then a sample of 15 mm in width and 70 mm in length was prepared with the film forming direction being matched with the shorter side direction, and then a tensile test was conducted at a tensile rate of 100 mm/min and a peeling distance of 30 mm by using an Instron Model 5567 Autograph. The tensile load at the time of peeling was defined as the bonding strength.

[0073]

[Example 1]

<Polypropylene pellets>

Ninety-six parts by weight of polypropylene A (a propylene-ethylene-1-butene random copolymer; the content of structural units derived from ethylene: 0.8% by weight, the content of structural units derived from -butene: 9.1 % by weight, Tm: 37°C, CXS: 1.4% by weight, MFR: 6.6 g/ 0 min), 4 parts by weight of a high density polyethylene (Density=0.955g/cm ³ MFR=16 g/10min, produced by Keiyo Polyethylene Co., Ltd.), and per 100 parts by weight of the polypropylene A and the high density polyethylene in total, 0.2 parts by weight of a silane coupling agent Silquest A-174NT (produced by Momentive Performance Materials), 0.01 parts by weight of hydrotalcite DHT-4C (produced by Kyowa Chemical Industry Co., Ltd.), 0.10 parts by weight of Irganox 1010 (produced by Ciba Specialty Chemicals), 0.05 parts by weight of Irgafos 168 (produced by Ciba Specialty Chemicals), and 0.25 parts by weight of aluminosilicate JC40 (produced by Mizusawa Industrial Chemicals, Ltd.) were added and melt-kneaded, affording polypropylene pellets having an MFR of 7.3 g/10 min.

[0074]

<Film to be used as a polypropylene layer of a metallized film>

The resulting pellets of polypropylene were melt-extruded at a resin temperature of 240°C by using a 40 mm T-die film-forming apparatus (manufactured by Modem Machinery Co., MCAG40/400 type film-forming apparatus, with a 400 mm wide T-die). The melt-extruded resin was cooled on a chill roll in which 50°C cooling water was circulated, affording a film 30 μηη in thickness to be used as a polypropylene layer of a metallized film. Using a corona-treater attached to said apparatus, corona treatment was applied to a surface to which metal was to be vapor deposited.

[0075]

<Aluminum vapor-deposited polypropylene film>

Using a vacuum deposition apparatus (DSC-500A, manufactured by Daehan Vacuum Engineering), aluminum was vapor-deposited to the above-obtained film on its corona-treated surface, affording a polypropylene film on which aluminum was deposited (aluminum-deposited polypropylene film). The film just before applying the vapor deposition of aluminum had a wetting tension of 42 dyne/cm. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1.

[0076]

[Example 2]

Pellets of polypropylene having an MFR of 7.3 g/ΪΟ minutes, were obtained in the same way as Example 1 except for changing the amount of the silane coupling agent A-174NT added to 0.4 parts by weight. Using the resulting pellets of the polypropylene having an MFR of 7.3 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The film just before applying the vapor deposition of aluminum had a wetting tension of 42 dyne/cm. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1.

[0077]

[Example 3]

Pellets of polypropylene having an MFR of 7.3 g/10 minutes were obtained in the same way as Example 1 except for using KBE-903 produced by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent and adjusting the loading thereof to 0.2 parts by weight. Using the resulting pellets of the polypropylene having an MFR of 7.3 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The film just before applying the vapor deposition of aluminum had a wetting tension of 42 dyne/cm. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1.

[0078]

[Example 4]

Pellets of polypropylene having an MFR of 7.3 g/10 minutes were obtained in the same way as Example 1 except for using KBE-903 produced by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent and adjusting the loading thereof to 0.4 parts by weight. Using the resulting pellets of the polypropylene having an MFR of 7.3 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The film just before applying the vapor deposition of aluminum had a wetting tension of 42 dyne/cm. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1.

[0079]

[Example 5]

100 parts by weight of polypropylene A, 0.2 parts by weight of a silane coupling agent KBE-903 produced by Shin-Etsu Chemical Co., Ltd., 0.01 parts by weight of hydrotalcite DHT-4C (produced by Kyowa Chemical Industry Co., Ltd.), 0.10 parts by weight of Irganox 1010 (produced by Ciba Specialty Chemicals), 0.05 parts by weight of Irgafos 168 (produced by Ciba Specialty Chemicals), and 0.25 parts by weight of aluminosilicate JC40 (produced by Mizusawa Industrial Chemicals, Ltd.) were added and melt-kneaded, affording pellets of polypropylene having an MFR of 6.6 g/10 minutes. Using the resulting pellets of the polypropylene having an MFR of 6.6 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1.

[0080]

[Example 6]

100 parts by weight of polypropylene A, 0.2 parts by weight of a silane coupling agent KBE-903 produced by Shin-Etsu Chemical Co., Ltd., 0.01 parts by weight of hydrotalcite DHT-4C (produced by Kyowa Chemical Industry Co., Ltd.), 0.10 parts by weight of Irganox 1010 (produced by Ciba Specialty Chemicals), and 0.05 parts by weight of Irgafos 168 (produced by Ciba Specialty Chemicals) were added and melt-kneaded, affording pellets of polypropylene having an MFR of 6.6 g/10 minutes. Using the resulting pellets of the polypropylene having an MFR of 6.6 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1. [0081]

[Comparative Example 1]

Pellets of polypropylene having an MFR of 7.3 g/10 minutes were obtained by conducting melt-kneading in the same way as Example 1 except for failing to add the silane coupling agent A-174NT. Using the resulting pellets of the polypropylene having an MFR of 7.3 g/ 0 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The film just before applying the vapor deposition of aluminum had a wetting tension of 44 dyne/cm. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table .

[0082]

[Comparative Example 2]

100 parts by weight of polypropylene A, 0.01 parts by weight of hydrotalcite DHT-4C (produced by Kyowa Chemical Industry Co., Ltd.), 0.10 parts by weight of Irganox 1010 (produced by Ciba Specialty Chemicals), 0.05 parts by weight of Irgafos 168 (produced by Ciba Specialty Chemicals), and 0.25 parts by weight of aluminosilicate JC40 (produced by Mizusawa Industrial Chemicals, Ltd.) were added and melt-kneaded, affording pellets of polypropylene having an MFR of 6.9 g/10 minutes. Using the resulting pellets of the polypropylene having an MFR of 6.9 g/10 minutes, a film to be used for as a polypropylene layer of a metallized film and an aluminum-deposited polypropylene film were obtained in the same way as in Example 1. The bonding strength of the resulting aluminum-deposited polypropylene film and the gloss and the anti-blocking of the film before the vapor deposition are given in Table 1. [0082]

[Table 1]

[0083]

The metallized films of Examples 1 through 6, which satisfy the requirements of the present invention, are found to be superior in bonding strength, that is, adhesion between a polypropylene layer and a metallized layer. In contrast, it has also been shown that Comparative Example 1 , which fails to satisfy the requirements of the present invention, is inferior in bonding strength. [0084]

The gloss of each of the films before given in Table 1 is a value for evaluating the appearance of a metallized film indicates whether a metallized film prepared by vapor-depositing a metal or a metal oxide onto the film forming the polypropylene layer containing the silane coupling agent of the present invention has good appearance or not.

There is a relationship of gloss between before and after metalizing, that is, when the gloss of plain film is better, the gloss of metalized film is better.

The anti-blocking of each of the films before vapor-deposition given in Table 1 indicates whether or not the film forming the polypropylene layer comprising the silane coupling agent of the present invention is less prone to undergo blocking and causes no problems in its use as a material of a metallized film.

Therefore, the above results show that the gloss and anti-blocking properties of the film can be maintained even after adding a silane coupling agent. Therefore, as there is a relationship between gloss before and after metallizing the film, the metal bonding strength can be improved without deteriorating the gloss. In addition, the inclusion of the silane coupling agent does not affect the anti-blocking properties of the resultant film before metallization. That means that the film may be processed normally.