JP2020104313A - Multilayer film and manufacturing method thereof - Google Patents

Abstract

To provide a multilayer film that has both whitening suppression and punching resistance while making full use of a transparency of acrylic.SOLUTION: The problem is solved by a multilayer film having a base film layer and a metal layer, having 50% or less total light transmittance, and satisfying conditions such as (1) dimensional change before and after holding at 85°C for 30 minutes is -10 μm or more, (2) when an isotropic biaxial stretching with an area stretching ratio of 140% is carried out at a stretching temperature of 140° C, a 20° gloss value is 900 or more, and (3) when punching using a punching device, a crack length of a test piece is less than 1.5 mm.SELECTED DRAWING: None

Description

The present invention relates to a multilayer film and a method for manufacturing the same.

Conventionally, in order to give a metallic luster to resin-made automobile wheel caps, bumpers, emblems, etc., it is common to apply a transparent luster paint after directly plating a resin member with metal. Was the way.

However, metal plating and coating are costly and have problems in environmental hygiene. Further, since the coating has a large variation in thickness, it is difficult to obtain a uniform appearance and it is difficult to provide stable quality. As a solution to such a problem, instead of metal plating, a metal thin film is formed on a base film to produce a metal decorative film, and instead of painting, the metal decorative film is applied to an adherend. There is a method of pasting.

For example, in Patent Document 1, a biaxially stretched polyethylene terephthalate film, an acrylic resin film or a polycarbonate resin film is used, and the maximum average height Rtm of the back surface is 0.1 to 2.0 μm and the haze value is 0. A metal-tone sheet having a metal vapor deposition layer containing at least one selected from tin, gold and indium on the back surface of a transparent resin film of 1 to 4.0% is disclosed.

Further, in Patent Document 2, a metal-like sheet using an acrylic resin film in which acrylic rubber particles having an acid value of 0.2 mmol/g or more are blended in the acrylic resin film to achieve both processability and metal adhesion. Is disclosed.

JP, 2008-110518, A International Publication No. 2012/053190

Acrylic films have been attracting attention as metal-like decorative applications because of their high transparency as in the prior art, but when a large amount of rubber components that contribute to the improvement of processability are added, the transparency characteristic of acrylic during molding is high. Therefore, the applicant has proceeded with the development of a decorative film whose workability is improved by the stretching technique. However, in a multilayer film having a stretched acrylic film layer and a metal layer, whitening peculiar to the stretched film may occur depending on the film used for heat molding, and the metallic tone may be impaired. Further, when the stretching conditions are changed to suppress whitening, whitening is suppressed depending on the acrylic film used, but after bonding to an adherend, when cutting out a surplus portion by punching into a desired shape. However, there was a problem that cracks and cracks occurred from the cut surface.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention including the following aspects. That is, the present invention is a multilayer film having a base film layer and a metal layer, having a total light transmittance of 50% or less and satisfying the following conditions.
(1) The dimensional change of the multilayer film before and after being held at 85° C. for 30 minutes is −10 μm or more. (2) When the multilayer film is isotropically biaxially stretched at a stretching temperature of 140° C. and an area stretching ratio of 140%. , 20° gloss value is 900 or more (3) When the multilayer film is punched using a punching device, the crack length of the test piece is 1.5 mm or less. Further, the base film is made of an amorphous resin. It is more preferably made of a (meth)acrylic resin.

（式中：Ｒ^１およびＲ^２は、それぞれ独立して、水素原子またはアルキル基を表す。）

（式中：Ｒ^３およびＲ^４は、それぞれ独立して、水素原子またはアルキル基を表す。） Further, the base film has a glass transition temperature _{T A} is 140 ° C. or less (meth) 99.9 to 20 wt% of an acrylic resin (A), a glass transition temperature _{T B} is _(T A + 10 ° C.) or higher It is preferable that the thermoplastic resin composition [C] contains 0.1 to 80% by mass of the thermoplastic resin [B], which is a polycarbonate resin, at least the following: A copolymer composed of a structural unit derived from an aromatic vinyl compound represented by the general formula (a) and a structural unit derived from an acid anhydride represented by the following general formula (b), and a syndiotactic triad. At least one thermoplastic resin selected from the group consisting of methacrylic resins having a tisity (rr) of 58% or more and a content of structural units derived from methyl methacrylate of 90% by mass or more. It is more preferable that it contains.

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group.)

(In the formula: R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group.)

On the other hand, the metal layer preferably contains at least one selected from the group consisting of indium, aluminum, chromium, gold, silver and tin, and the thickness of the metal layer is preferably 10 to 500 nm.

The thickness of the base film is preferably 5 to 200 μm, and the adhesion between the base film layer and the metal layer is preferably 1.0 N/25 mm or more.
Further, the base film is preferably a stretched film.

As a method for producing a multilayer film according to the present invention, after drawing a glass transition temperature T _C above the temperature of the resin composition (C), it was thermally fixed at a temperature of less than (T C _-25 ° C.) or higher T _C It is preferable to use a substrate film for the stretched film, and it is more preferable that the stretch ratio at the time of stretching is 1.5 to 8.0 times.
The stretch ratio means the ratio of the area after stretching to the area before stretching.
Further, the stretching is preferably biaxial stretching.

Another aspect of the present invention is a metal-like decorative film comprising the above-mentioned multilayer film, which is a molded product having the above-mentioned multilayer film and an adherend.

ADVANTAGE OF THE INVENTION According to this invention, the multilayer film which makes whitening control and punching-proof property compatible can be provided, utilizing the transparency of acrylic.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. Numerical values specified in this specification are values obtained by the methods disclosed in the embodiments or examples. Other embodiments are also included in the scope of the present invention as long as they match the spirit of the present invention.

The multilayer film of the present invention has a base film layer and a metal layer, has a total light transmittance of 50% or less, and satisfies the following conditions.
(1) The dimensional change of the multilayer film before and after being held at 85° C. for 30 minutes is −10 μm or more. (2) When the multilayer film is isotropically biaxially stretched at a stretching temperature of 140° C. and an area stretching ratio of 140%. , 20° gloss value is 900 GU or more (3) When the multilayer film is punched using a punching device, the crack length of the test piece is 1.5 mm or less.

If the total light transmittance exceeds 50%, the quality as a metal-tone decorative film deteriorates due to the transmission. In order to make it 50% or less, it is preferable that the thickness of the metal layer is 30 nm or more. On the other hand, when the thickness of the metal layer exceeds 500 nm, the reflectance of the metal layer itself may decrease.

(Base film)
The substrate film of the present invention preferably has a haze value of 1% or less, more preferably 0.7% or less, and further preferably 0.5% or less. When the haze value is high, the transparency is lowered and the decoration effect of the metal layer is impaired.

The base film of the present invention is preferably made of an amorphous resin from the viewpoint of transparency. Since the amorphous resin has a low haze value and high transparency, the decoration effect of the metal layer is high. As used herein, "amorphous resin" means a resin that does not have a distinct melting point on a differential scanning calorimetry (DSC) curve.

Examples of the amorphous resin include polystyrene, polyvinyl chloride, acrylonitrile styrene resin, polycarbonate, isosorbide-based copolycarbonate, amorphous polypropylene, amorphous polyethylene terephthalate, and methacrylic resin. Among them, (meth)acrylic resins are preferable from the viewpoints of transparency, weather resistance, surface gloss, and scratch resistance.

The (meth)acrylic resin used as the substrate film preferably has a glass transition temperature of 100° C. or higher and 150° C. or lower from the viewpoint of heat resistance and moldability.

The base film is more preferably 99.9 to 20% by mass of (meth)acrylic resin [A] having a glass transition temperature T _A of 140° C. or less, and a glass transition temperature T _B of (T _A +10° C.). It is made of an acrylic resin containing 0.1 to 80% by mass of the above thermoplastic resin [B].

In the present specification, the “glass transition temperature” is a midpoint glass transition temperature determined from the DSC curve by measuring the DSC curve under conditions of increasing temperature using a differential scanning calorimeter according to JIS K7121. is there. The glass transition temperature can be measured by the method described in the section [Example].

<(Meth)acrylic resin (A)>
The (meth)acrylic resin (A) is not particularly limited as long as it is a (meth)acrylic polymer having a glass transition temperature T _A of 140° C. or lower and a mixture thereof. The (meth)acrylic resin (A) contains at least one methacrylic acid ester monomer unit such as a methyl methacrylate (MMA) monomer unit. Examples of the methacrylic acid ester include methacrylic acid alkyl esters such as MMA, ethyl methacrylate, and butyl methacrylate; methacrylic acid aryl esters such as phenyl methacrylate; cyclomethacrylic acid cycloalkyl esters such as cyclohexyl methacrylate and norbornenyl methacrylate. Are listed. In addition, in this specification, a (meth)acrylic resin refers to a methacrylic resin and/or an acrylic resin. The (meth)acrylic resin may be a heat-resistant (meth)acrylic resin modified by imide cyclization, lactone cyclization, methacrylic acid modification or the like. Further, the base film may contain one kind or two or more kinds of these (meth)acrylic resins.

The ratio of the structural unit derived from methyl methacrylate in the (meth)acrylic resin is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and further It is preferably 99% by mass or more, and particularly preferably 100% by mass. That is, the ratio of the structural unit derived from a monomer other than methyl methacrylate is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, and further It is preferably 1% by mass or less, and particularly preferably 0% by mass.

Examples of such monomers other than methyl methacrylate include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, acrylic acid. t-butyl, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, phenyl acrylate, benzyl acrylate, phenoxyethyl acrylate, acrylic acid Acrylic esters such as 2-hydroxyethyl, 2-ethoxyethyl acrylate, glycidyl acrylate, allyl acrylate, cyclohexyl acrylate, norbornyl acrylate, isobornyl acrylate; ethyl methacrylate, n-propyl methacrylate, methacryl Isopropyl acetate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Pentadecyl, dodecyl methacrylate, phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate, glycidyl methacrylate, allyl methacrylate, cyclohexyl methacrylate, norbornyl methacrylate. , Methacrylic acid esters other than methyl methacrylate such as isobornyl methacrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, maleic acid, itaconic acid; ethene, propylene, 1-butene, isobutene, 1-octene Olefins such as butadiene; isoprene, myrcene and other conjugated dienes; styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, and other aromatic vinyl compounds; acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate , Vinyl pyridine, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride and the like. These monomers may be used alone or in combination of two or more.

The Mw of the (meth)acrylic polymer is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, and particularly preferably 50,000 to 120,000. When the Mw is 40,000 or more, the mechanical strength (impact resistance, toughness, etc.) of the obtained molded article tends to be improved, and when it is 200,000 or less, the fluidity of the (meth)acrylic resin composition is improved. Then, the moldability tends to be improved.

The molecular weight distribution (Mw/Mn) of the (meth)acrylic polymer is preferably 1.6 to 5.0, more preferably 1.7 to 4.0, and particularly preferably 1.7 to 3.0. is there. When a (meth)acrylic copolymer having a molecular weight distribution (Mw/Mn) within this range is used, the resulting molded article has excellent mechanical strength. Mw and Mw/Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used during the production of the (meth)acrylic polymer.

The method for producing the (meth)acrylic polymer is not particularly limited, and it can be obtained by polymerizing one or more kinds of monomers containing methyl methacrylate preferably at 80% by mass or more under suitable conditions.

<Thermoplastic resin (B)>
Thermoplastic resin (B), the glass transition temperature _{T A} of the glass transition temperature _{T B} of the thermoplastic resin (B) is (meth) acrylic resin _(A), the long _(T A + 10 ° C.) or higher , Not particularly limited. As the thermoplastic resin used for the thermoplastic resin layer, for example,
Olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly(4-methyl-1-pentene);
Cyclic olefin resins such as polycycloolefin and polynorbornene;
Halogen-containing resins such as vinyl chloride resin and chlorinated vinyl resin;
Styrene resins such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, α-methylstyrene-methyl methacrylate copolymer, and acrylonitrile-butadiene-styrene block copolymer;
(Meth)acrylic acid ester homopolymer, (meth)acrylic acid ester copolymer, (meth)acrylic acid ester and N-substituted maleimide copolymer, (meth)acrylic acid ester and (meth)acrylic acid (Meth)acrylic resins such as copolymers with anhydrides and copolymers of (meth)acrylic acid esters and glutarimide;
Ester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate;
Amide-based resins such as nylon 6, nylon 66, and nylon 610;
Cellulosic resins such as triacetyl cellulose;
Acetal resin;
Carbonate resin;
Phenylene oxide resin;
Phenylene sulfide resin;
Ether ether ketone resin;
Ether nitrile resin;
Sulfone resin;
Ether sulfone resin;
Oxypentylene resin;
Amide-imide resin;
Phenoxy resin, and
SMA resin etc. are mentioned.

Among the above-mentioned thermoplastic resins, a resin compatible with the (meth)acrylic resin (A) is preferable from the viewpoint of transparency, and has a high syndiotacticity (rr) in triplet indication (meth). Examples thereof include an acrylic resin (B1), a polycarbonate resin (B2), and a copolymer (B3) including at least a structural unit derived from an aromatic vinyl compound (a) and a structural unit derived from an acid anhydride (b). To be

<(Meth)acrylic resin (B1)>
The (meth)acrylic resin (B1) has a triad indication syndiotacticity (rr) of 65% or more, preferably 70 to 90%, more preferably 72 to 85%. When the syndiotacticity (rr) is 65% or more, the glass transition temperature (T _B ) is significantly increased, and the heat resistance of the obtained base film is increased.
The molecular weight distribution (Mw/Mn) of the (meth)acrylic resin (B1) is preferably 1.0 to 1.8, more preferably 1.0 to 1.4, and particularly preferably 1.03 to 1.3. Is. Mw and Mw/Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used during production.

The (meth)acrylic resin (B1) may contain one or more kinds of monomer units other than the above MMA monomer units. Other monomer units include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; aryl acrylates such as phenyl acrylate; Acrylic acid cycloalkyl esters such as cyclohexyl acrylate and norbornenyl acrylate; Aromatic vinyl compounds such as styrene and α-methylstyrene; Polymerizable carbons in one molecule such as nitriles such as acrylonitrile and methacrylonitrile -Structural units derived from vinyl-based monomers having only one carbon double bond.

The Mw of the (meth)acrylic resin (B1) is preferably 40,000 to 200,000, more preferably 40,000 to 150,000, and particularly preferably 50,000 to 120,000. If the Mw is 40,000 or more, the mechanical strength (impact resistance and toughness, etc.) of the obtained molded article tends to be improved, and if it is 200,000 or less, the fluidity of the (meth)acrylic resin composition is improved. Moldability tends to improve.
The melt flow rate (MFR) of the (meth)acrylic resin (B1) measured under the conditions of 230° C. and a load of 3.8 kg is preferably 0.1 g/10 minutes or more, more preferably 0.2 to 30 g/ It is 10 minutes, particularly preferably 0.5 to 20 g/10 minutes, most preferably 1.0 to 15 g/10 minutes.

As a method for controlling the syndiotacticity (rr) represented by triplets and the molecular weight distribution (Mw/Mn), a controlled polymerization method can be mentioned, and a living radical polymerization method and a living anionic polymerization are preferable. Living radical polymerization methods include atom transfer radical polymerization (ATRP) method, reversible addition fragmentation chain transfer polymerization (RAFT) method, nitroxide mediated polymerization (NMP) method, boron mediated polymerization method, and catalyst transfer polymerization (CCT) method. Are listed. As the (living) anionic polymerization method, a method of using an organic alkali metal compound as a polymerization initiator and performing anion polymerization in the presence of a mineral acid salt such as a salt of an alkali metal or an alkaline earth metal (see Japanese Patent Publication No. 7-25859). ), an anionic polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organic aluminum compound (see JP-A-11-335432), and a method of anionic polymerization using an organic rare earth metal complex as a polymerization initiator (special Kaihei 6-93060) and the like.

<Polycarbonate (B2)>
Examples of the polycarbonate (PC) include polymers obtained by reacting a polyfunctional hydroxy compound with a carbonic acid ester forming compound. From the viewpoint of compatibility with the (meth)acrylic resin and transparency of the resulting molded article, aromatic polycarbonate is preferable.
Polycarbonate (PC) is a melt volume flow rate measured under the conditions of 300° C. and a load of 1.2 kg from the viewpoint of compatibility with (meth)acrylic resin and transparency and surface smoothness of the obtained molded product. (MVR) is preferably 15 to 250 cm ³ /10 minutes, more preferably 20 to 230 cm ³ /10 minutes, and particularly preferably 25 to 220 cm ³ /10 minutes.

Polycarbonate (PC) has a Mw in terms of polystyrene of preferably 15,000 to 40,000, and more preferably 18,000 from the viewpoint of compatibility with a (meth)acrylic resin and transparency and surface smoothness of the obtained molded product. It is 39000, particularly preferably 20000-38000.
The MVR and Mw of the polycarbonate (PC) can be controlled by adjusting the amounts of the end terminator and/or the branching agent.
The glass transition temperature of polycarbonate (PC) is preferably 130° C. or higher, more preferably 135° C. or higher, and particularly preferably 140° C. or higher. The upper limit of the glass transition temperature is usually 180°C.

Examples of the method for producing polycarbonate (PC) include a phosgene method (interfacial polymerization method) and a melt polymerization method (transesterification method). The aromatic polycarbonate can be produced by subjecting the polycarbonate raw material produced by the melt polymerization method to a treatment for adjusting the amount of terminal hydroxy groups.
Polycarbonate (PC) may contain other structural units such as polyester, polyurethane, polyether, or polysiloxane in addition to the polycarbonate structural unit.

<SMA resin (B3)>
The SMA resin has at least a structural unit derived from an aromatic vinyl compound (a) represented by the following general formula (a) and a structural unit derived from an acid anhydride (b) represented by the following general formula (b). Is a copolymer of

（式中：Ｒ^１およびＲ^２は、それぞれ独立して、水素原子またはアルキル基を表す。）

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group.)

（式中：Ｒ^３およびＲ^４は、それぞれ独立して、水素原子またはアルキル基を表す。）

(In the formula: R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group.)

The alkyl group represented by R ¹ and R ² in the general formula (a) and R ³ and R ⁴ in the general formula (b) independently represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, n-butyl group, sec-butyl group, isobutyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, nonyl An alkyl group having 12 or less carbon atoms such as a group, a decyl group and a dodecyl group is preferable, and a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a t-butyl group. More preferred are alkyl groups having 4 or less carbon atoms.

R ₁ is preferably a hydrogen atom, a methyl group, an ethyl group or a t-butyl group. As R ² , R ³ and R ⁴ , a hydrogen atom, a methyl group and an ethyl group are preferable.

The content of the structural unit derived from the aromatic vinyl compound (a) in the SMA resin is preferably in the range of 50 to 85% by mass, more preferably 55 to 82% by mass, and 60 to 80% by mass. It is more preferable that the range is %. When the content is in the range of 50 to 85% by mass, the resin composition (C) has excellent moisture resistance and transparency.

Examples of the aromatic vinyl compound (a) include styrene; nuclear alkyl-substituted styrene such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, and 4-tert-butylstyrene; α-methylstyrene. Α-alkyl-substituted styrene such as 4-methyl-α-methylstyrene; and styrene is preferable from the viewpoint of availability. These aromatic vinyl compounds (a) may be used alone or in combination of two or more.

The content of the structural unit derived from the acid anhydride (b) in the SMA resin is preferably 15 to 50% by mass, more preferably 18 to 45% by mass, and more preferably 20 to 40% by mass. More preferably, it is in the range of mass%. When the content is in the range of 15 to 50% by mass, the resin composition (B3) has a high glass transition temperature and excellent mechanical strength.

Examples of the acid anhydride (b) include maleic anhydride, citraconic anhydride, dimethyl maleic anhydride and the like, and maleic anhydride is preferable from the viewpoint of availability. These acid anhydrides (b) may be used alone or in combination of two or more.

The SMA resin may contain a structural unit derived from a methacrylic acid ester monomer in addition to the aromatic vinyl compound (a) and the acid anhydride (b).

Examples of the methacrylic acid ester include MMA, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and t-butyl methacrylate. 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate; and the like. Among these methacrylic acid esters, methacrylic acid alkyl esters having an alkyl group with 1 to 7 carbon atoms are preferable, and MMA is particularly preferable because the obtained SMA resin has excellent heat resistance and transparency. The methacrylic acid ester may be used alone or in combination of two or more.

The SMA resin may have a structural unit derived from a monomer other than the aromatic vinyl compound (a), the acid anhydride (b) and the methacrylic acid ester. Examples of the other monomer include MA, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate. , Nonyl acrylate, decyl acrylate, dodecyl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, acrylic Acid 3-methoxybutyl, trifluoromethyl acrylate, trifluoroethyl acrylate, pentafluoroethyl acrylate, glycidyl acrylate, allyl acrylate, phenyl acrylate, toluyl acrylate, benzyl acrylate, isobornyl acrylate, acrylic acid An acrylic acid ester such as 3-dimethylaminoethyl may be mentioned. These other monomers may be used alone or in combination of two or more. The content of the structural unit derived from the other monomer in the SMA resin is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 2% by mass or less.

The SMA resin can be obtained by polymerizing the aromatic vinyl compound (a), the acid anhydride (b), the methacrylic acid ester, and another monomer which is an optional component. In such polymerization, usually, the monomers to be used are mixed to prepare a monomer mixture, which is then subjected to the polymerization. The polymerization method is not particularly limited, but from the viewpoint of productivity, radical polymerization is preferably performed by a method such as a bulk polymerization method or a solution polymerization method.

The Mw of the SMA resin is preferably in the range of 40,000 to 300,000. When the Mw is 40,000 or more, the base film has excellent heat resistance and impact resistance, and when it is 300,000 or less, the processability of the base film is excellent, and the multilayer film of the present invention is excellent. The productivity of the film can be improved.

<Thermoplastic resin composition (C)>
The thermoplastic resin composition (C) is a resin composition including the (meth)acrylic resin (A) and the thermoplastic resin (B).
The content of the thermoplastic resin composition (B) from the viewpoint of manifesting the effect based on the thermoplastic resin composition (B) contained in the thermoplastic resin composition (C) used in the present invention (improvement in punchability). Is 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more.

From the viewpoint of the balance of physical properties of the thermoplastic resin composition (C), the content of the thermoplastic resin (B) is 80 mass% or less, preferably 20 mass% or less. The thermoplastic resin (B) is preferably added in a small amount in view of taking advantage of the characteristics such as thermal stability and transparency of the (meth)acrylic resin. For example, in the case of the thermoplastic resin composition (C) containing the (meth)acrylic resin (A) and the (meth)acrylic resin (B1), if the (meth)acrylic resin (B1) is too much, heating will occur. The thermal stability of time is impaired. In the case of the thermoplastic resin composition (C) containing the (meth)acrylic resin (A) and the polycarbonate (B2), if the polycarbonate (B2) is too much, the transparency tends to be impaired. In the case of the thermoplastic resin composition (C) containing the (meth)acrylic resin (A) and the SMA resin (B3), if the amount of the SMA resin (B3) is too much, the impact resistance tends to be impaired.

(Other polymers)
The (meth)acrylic resin composition of the present invention may optionally contain one or more other polymers other than the (meth)acrylic resin (A) and the thermoplastic resin (B). The other polymer may be added during or after the polymerization of the (meth)acrylic resin (A) and/or the thermoplastic resin (B), or the (meth)acrylic resin (A) It may be added at the time of kneading the plastic resin (B).

Examples of other polymers include aromatic vinyl resins such as polystyrene, styrene-acrylonitrile resin, styrene-maleic anhydride resin, styrene-maleimide resin, and styrene-based thermoplastic elastomers, or hydrogenated products thereof; amorphous polyolefins. , A transparent polyolefin with a finer crystal phase, a polyolefin resin such as ethylene-methyl methacrylate resin; a polyester such as polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polyarylate partially modified with cyclohexanedimethanol or isophthalic acid. Examples of the resin include a polyamide resin, a polyimide resin, a polyether sulfone resin, a cellulose resin such as triacetyl cellulose resin, a polyphenylene oxide resin, and a phenoxy resin. The base film may contain only one kind of these resins, or may contain two or more kinds thereof. Among these, the base film preferably contains a phenoxy resin. When the base film contains a phenoxy resin, the metallic gloss of the multilayer film is further improved.

When the base film contains one or more other polymers other than the ((meth)acrylic resin (A) and the thermoplastic resin (B), the content thereof is 100 parts by mass of the (meth)acrylic resin. On the other hand, it is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less. When the content of the resin is in the range, the multilayer film has excellent surface hardness and weather resistance.

The base film may include an elastomer. Examples of the elastomer include (meth)acrylic elastic particles and (meth)acrylic block copolymers in which the acrylic ester polymer block (b1) and the methacrylic acid ester polymer block (b2) are bonded. (Meth)acrylic elastomers; silicone elastomers; styrene thermoplastic elastomers such as SEPS, SEBS, SIS; olefin elastomers such as IR, EPR and EPDM. These elastomers may be used alone or in combination of two or more.

The content of the elastomer in the base film is preferably 10 parts by mass or less, more preferably 4 parts by mass or less, still more preferably 1 part by mass or less, relative to 100 parts by mass of the (meth)acrylic resin. When the content of the elastomer is within such a range, the multilayer film tends to have more excellent metallic luster and surface hardness. In addition, the range of the above content includes an embodiment in which the elastomer is not included. The inclusion of the elastomer improves the toughness, but when the content of the elastomer increases, the haze of the film increases and the quality of the multilayer film is apt to deteriorate.

The base film may contain additives. The type of additive is not particularly limited, and examples thereof include an ultraviolet absorber, an infrared absorber, a polymer processing aid, a light stabilizer, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a pigment, a dye, and a matting agent. Agents, fillers, impact resistance aids, plasticizers and the like. One kind of the additive may be used alone, or two or more kinds thereof may be used in combination at an arbitrary ratio. The base film preferably contains a polymer processing aid from the viewpoint of enhancing the moldability of the base film. Although these additives may be organic compounds or inorganic compounds, organic compounds are preferable from the viewpoint of dispersibility in the resin composition.

The content of the additive in the base film is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and further preferably 3 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic resin. is there. When the content of the additive is within the above range, the multilayer film has excellent impact resistance and surface hardness.

Here, when the single-layer transparent film is used as a decorative film or the like, light is usually emitted from only one surface. On the other hand, since the multilayer film of the present invention has the metal layer, the base film is exposed to the incident light and the light reflected by the metal layer, and the deterioration due to the light is likely to proceed. Therefore, the base film is required to have a higher weather resistance than that of an ordinary transparent film, and therefore it is preferable that the base film contains an ultraviolet absorber. The content of the ultraviolet absorber in the base film is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, with respect to 100 parts by mass of the (meth)acrylic resin, and It is preferably 0.5 to 3 parts by mass. When the content of the ultraviolet absorber is within the above range, a multilayer film having excellent weather resistance and hardly causing whitening even after long-term storage can be obtained. Examples of the ultraviolet absorber include benzophenone compounds, salicylate compounds, benzoate compounds, triazole compounds and triazine compounds. The ultraviolet absorbers may be used alone or in combination of two or more at an arbitrary ratio. Among these, triazole compounds and/or triazine compounds are preferable from the viewpoint of long-term stability. Further, from the viewpoint of further increasing the weather resistance, it is also preferable to use a light stabilizer and/or an antioxidant together with the ultraviolet absorber. Examples of the light stabilizer include hindered amine light stabilizers and the like. Examples of antioxidants include phenolic antioxidants.

As the polymer processing aid, polymer particles having a particle diameter of 0.05 to 0.5 μm, which can be produced by an emulsion polymerization method, can be used. When the base film contains the polymer processing aid, the thickness accuracy and the film-forming stability are improved when the resin composition is molded, and fisheye defects can be reduced. Representative products of the polymer processing aid include Kane Ace PA series (manufactured by Kaneka), Metabrene P series (manufactured by Mitsubishi Rayon Co., Ltd.), and Paraloid K series (manufactured by Dow). Among these, from the viewpoints of reducing fisheye defects of the base film, improving molding stability during film formation, and particularly improving molding stability of the film end portion, methyl methacrylate is 60 to 90% by mass, and alkyl acrylate is 10%. A polymer processing aid contained in an amount of ˜40% by mass is preferable, Metabrene P530, P550 and Paraloid K125 are more preferable, and Metabrene P550 is particularly preferable.

The polymer particles constituting the polymer processing aid may be single layer particles composed of a polymer having a single composition ratio and a single intrinsic viscosity, or may be two or more kinds of polymer particles having different composition ratios or intrinsic viscosities. It may be a multi-layered particle composed of coalesced particles. Among these, particles having a two-layer structure having a polymer layer having a low intrinsic viscosity in the inner layer and a polymer layer having a high intrinsic viscosity of 5 dl/g or more in the outer layer are preferable.

When the polymer processing aid is a single layer particle, the intrinsic viscosity is preferably 3 to 6 dl/g. If the intrinsic viscosity is too small, the effect of improving moldability is low. If the intrinsic viscosity is too large, the melt fluidity of the resin composition tends to deteriorate.

(Multilayer film)
The present invention is a multilayer film comprising a base film layer and a metal layer. The total light transmittance of the multilayer film is 50% or less, preferably 30% or less, more preferably 20% or less, and further preferably 10% or less. When the total light transmittance is 50% or less, the multilayer film has excellent metallic luster and can be suitably used as a metallic decorative film. The total light transmittance of the multilayer film can be determined according to JIS K 7136, and specifically, it can be determined by the method described later in Examples.

As described above, the multilayer film of the present invention has a dimensional change of −10 μm or more before and after being held at 85° C. for 30 minutes. Regardless of the specific direction of the multilayer film, both the longitudinal direction (MD) and the width direction (TD) of the multilayer film are related ranges. When the amount of shrinkage is large, the influence of film shrinkage during molding becomes large and whitening occurs on the metal surface, as described later.
The dimensional change of the multilayer film before and after holding at 85° C. for 30 minutes is preferably −10 μm or more, more preferably −8.0 μm or more. Further, it is preferably −0.5 μm or less, more preferably −1.0 μm or less. When the dimensional change rate of the multilayer film is within such a range, the multilayer film is excellent in stretchability and is less likely to break even when the multilayer film is subjected to vacuum pressure molding or insert molding. Further, it is more excellent in punching resistance. The dimensional change before and after holding the multilayer film at 85° C. for 30 minutes can be determined by using a stress/strain controlled thermomechanical analyzer, and specifically by the method described later in Examples.

In order for the multilayer film to have a dimensional change within the above range, the base film needs to have the same performance. The dimensional change before and after holding the base film at 85° C. for 30 minutes can be controlled by appropriately adjusting the type and amount of the resin or elastomer contained in the stretched film, the stretching temperature, the stretching ratio, the heat setting temperature, the relaxation rate, and the like. You can control.

As described above, the multilayer film of the present invention has a 20° gloss value of 900 GU or more when subjected to isotropic biaxial stretching with an area stretching ratio of 140% at a stretching temperature of 140°C. When the multilayer film is isotropically biaxially stretched at an stretching ratio of 140% at a stretching temperature of 140° C., if the glossiness is low, the glossiness of the molded product is low and the appearance quality is low.
The multilayer film preferably has a glossiness of 1000 GU or more when subjected to isotropic biaxial stretching with an area stretching ratio of 140% at a stretching temperature of 140°C. When the multi-layer film is subjected to isotropic biaxial stretching with an area stretching ratio of 140% at a stretching temperature of 140° C. and the glossiness is within the range, the appearance quality due to whitening of the metal layer and deterioration of the haze of the base film is deteriorated. A high-quality molded product can be obtained without deterioration.

As described above, the multilayer film of the present invention has a crack length of the test piece of 1.5 mm or less when the multilayer film is punched using a punching device. The multi-layer film has a long crack length under these conditions, after being bonded to an adherend, when punching out a desired shape and cutting off the excess portion, cracks (flaps) and breakage easily occur from the cut surface, Product yield deteriorates.

The multilayer film satisfying the above conditions can be satisfied by the following combination of the base film and the metal layer.

The method for molding the raw film containing the amorphous resin which is the base of the base film is not particularly limited, but, for example, the melt extrusion method is preferable. The melt extrusion method is not particularly limited, and the melt extrusion method known in the art can be used. For example, the T-die method or the inflation method can be used. At this time, the molding temperature is preferably 150 to 350°C, more preferably 200 to 300°C, and further preferably 240 to 280°C.

When a raw film is formed by the T-die method, a T-die can be connected to the tip of a known single-screw extruder or a twin-screw extruder to obtain a raw film extruded in a film shape.

The extruder preferably has one or more open vents. By using such an extruder, decomposed products and volatile components can be sucked from the open vent portion, and the quality of the obtained resin composition can be improved. Further, the extruder preferably has a polymer filter for removing foreign matters. Examples of the structure of the polymer filter include a leaf disk type and a candle type. Further, the extruder preferably has a gear pump in order to stabilize the discharge amount of the resin composition. Known gear pumps can be used. When the extruder has an open vent part, a gear pump and a polymer filter, it is preferable to connect the extruder, the gear pump, the polymer filter and the die in this order from the viewpoint of reducing foreign matters and suppressing vent up. Further, in order to prevent deterioration of the resin composition in the extruder, it is preferable to mold while passing nitrogen through the extruder.

As one embodiment for producing a raw film, from the viewpoint of surface smoothness and thickness uniformity of the base film, it is preferable to extrude the film-like molten resin between the mirror-finished rolls or mirror-finished belts and press it between them. .. Both the mirror surface roll and the mirror surface belt are preferably made of metal. More preferably, the mirror roll is a combination of a metal rigid roll and a metal elastic roll. The linear pressure between the mirror surface roll or the mirror surface belt is preferably 10 N/mm or more, more preferably 30 N/mm or more, from the viewpoint of surface smoothness. The surface temperature of the mirror surface roll or the mirror surface belt is preferably 60° C. or higher, more preferably 70° C. or higher from the viewpoint of surface smoothness, haze, appearance and the like. Further, it is preferably 130° C. or lower, and more preferably 100° C. or lower.

Further, as another embodiment for producing a raw film, the extruded film-shaped molten resin is contacted and adhered to a mirror surface roll by an adhesion assisting means from the viewpoint of surface smoothness and thickness uniformity of the base film. It is preferable to cool, solidify. Examples of the adhesion auxiliary device include an electrostatic adhesion device, an air knife, an air chamber, a vacuum chamber and the like. Among these, from the viewpoint of manufacturing stability, it is preferable to use an electrostatic contact device as the contact auxiliary device.

When both edge pinning and wire pinning are used as the adhesion assisting device, it is preferable to arrange the edge pinning and the wire pinning in this order from the upstream side. Further, it is more preferable that the wire pinning is arranged on the downstream side, including the position where the temperature of the molten resin on the mirror surface roll becomes the glass transition temperature, and on the upstream side of the position where it is separated from the mirror surface roll.

From the viewpoint of productivity, the thickness of the raw film is preferably 40 to 500 μm, more preferably 80 to 400 μm, and further preferably 100 to 300 μm. Here, the thickness of the original film is an average value of the central portion of 50 mm with respect to the entire width of the original film.

The raw film is preferably formed into a film and then subjected to a stretching treatment to obtain a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film, but a biaxially stretched film is preferable from the viewpoint of further improving the punching resistance of the multilayer film. The stretching treatment improves the mechanical strength of the film and improves punching resistance. The stretching method is not particularly limited, and examples thereof include a simultaneous biaxial stretching method, a sequential biaxial stretching method, a tuber stretching method, and a rolling method. The stretching treatment preferably has a preheating step, a stretching step, and a heat setting step in this order, and more preferably has a preheating step, a stretching step, a heat setting step, and a relaxation step in this order.

The preheating temperature is preferably T _C to (T _C +40° C.) in the sequential and simultaneous biaxial stretching methods based on the glass transition temperature (T _C ) of the thermoplastic resin composition (C) used in the present invention. more preferably a _{(T C + 5 ℃) ~} (T C + 35 ℃). If it is lower than the above range, the film may be broken and cannot be stretched. If it is higher than the above range, mechanical strength may not be improved even if stretching is performed.

Stretching temperature, the thermoplastic resin composition used in the present invention the glass transition temperature of _(C) (T C) as a reference, in the sequential and simultaneous biaxial stretching method, preferably _{T C ~ (T C + 40} ℃), more preferably a _{(T C + 5 ℃) ~} (T C + 35 ℃). If it is lower than the above range, the film may be broken and cannot be stretched. If it is higher than the above range, mechanical strength may not be improved even if stretching is performed.

In the stretching step, the stretching ratio is preferably 1.5 to 8.0 times, more preferably 2.0 to 6.0 times, and further preferably 2.5 to 4.0 times. When the stretching ratio is 1.5 times or more, the punching resistance of the multilayer film is further improved. In addition, when the draw ratio is 8.0 times or less, and particularly 4.0 times or less, the multilayer film is excellent in stretchability, and even if the multilayer film is subjected to vacuum pressure molding or insert molding, breakage hardly occurs. Further, when the stretching ratio is 8.0 times or less, particularly 4.0 times or less, the shrinkage amount of the multilayer film can be suppressed to a low level, and the whitening of the metal surface during molding can be suppressed. The stretch ratio means the ratio of the area after stretching to the area before stretching.

In the stretching step, the stretching speed is preferably 100 to 5000%/min, more preferably 200 to 2000%/min. When the stretching speed is within the above range, breakage is less likely to occur in the stretching process during the production of the stretched film, and the productivity is improved.

The stretching treatment preferably has a heat setting step after the stretching step. By heat setting, a base film having excellent stretchability and small heat shrinkage can be obtained.
The heat setting step is performed by holding the stretched film in a predetermined temperature range for a predetermined time in a state in which both ends in at least one direction of the film are constrained under a predetermined temperature range condition, and heat resistance and The effect of improving the mechanical strength can be obtained. Such thermal fixing step, based on the glass transition temperature _{T C} of the thermoplastic resin composition _{(C), (T C -25} ℃) less than _{T C,} preferably _(T C -20 ℃) less than _{T C,} more preferably _(T C -15 ℃) or _{T C} below the temperature. By the heat setting step in the temperature range, the orientation state and relaxation state of each component constituting the resin composition (C) can be precisely controlled, and a film satisfying high heat resistance and punchability can be obtained. Further, when the content ratio of the compounding ingredients that anticipates the effect is low, the compounding effect is hardly exhibited, but when the content of the thermoplastic resin (B) is set to a low content ratio where the effect is not generally expected by the above control, It becomes possible to satisfy the physical properties. Shrinkage starting temperature when the heat setting temperature is lower than (T C _-25 ℃) tends to decrease significantly.

The mechanism by which the action in the heat-fixing step of the present invention is expressed is being investigated, but it is presumed to be the following mechanism.
In the stretching step, the (meth)acrylic resin (A) and the thermoplastic resin (B) are cooperatively molecularly oriented. When the heat setting temperature is higher than T _C , both components cooperatively relax. If the heat setting temperature is lower than (T _C +25)° C., it does not relax sufficiently. When heat-set at less than T _C ° C. temperature range (T C _-25) ° C. or higher of the present invention, (meth) only acrylic resin (A) is independently relaxes, shrinkage starting temperature effect is exhibited to rise, Since the thermoplastic resin (B) is not relaxed, the punching property is enhanced.

The stretching treatment preferably further includes a relaxation step after the heat setting step. By the relaxation step, it is possible to obtain a multilayer film that is more excellent in stretchability. The relaxation rate is preferably 0.1% to 5%, more preferably 0.5 to 2%.

The thickness of the substrate film is preferably 5 to 200 μm, more preferably 10 to 100 μm, still more preferably 20 to 80 μm, and still more preferably 30 to 60 μm from the viewpoint of cost and surface hardness. is there.

The haze of the base film is preferably 1% or less, more preferably 0.8% or less, further preferably 0.5% or less, and particularly preferably 0.4% or less. When the haze of the base film is within the range, the multilayer film is excellent in metallic luster. The haze of the base film can be controlled by appropriately adjusting the type and amount of the resin or elastomer contained in the base film, the stretching temperature and the stretching ratio. The haze of the stretched film can be determined according to JIS K 7136, and specifically, it can be determined by the method described below in Examples.

The base film can be subjected to a surface treatment on at least one surface of the base film in order to improve the adhesive force with the metal layer described later. As the surface treatment, a method known in the art, for example, an activation treatment such as a corona discharge treatment, a plasma treatment, a glow discharge treatment, a flame treatment, an ultraviolet ray irradiation treatment, an electron beam irradiation treatment, or an ozone treatment is used. be able to.
The adhesive strength also affects whitening during stretch molding, and is preferably 1 N/25 mm or more, and more preferably 2 N/25 mm or more in order to improve the appearance quality. Even when shrinkage occurs due to the adhesive force being in the range, it is easy to maintain the adhesion of the metal layer to the base film, and the molding range for suppressing whitening is expanded.

(Metal layer)
Examples of the metal layer included in the multilayer film of the present invention include those made of metal and/or metal oxide. Examples of the metal include aluminum, silicon, magnesium, palladium, zinc, tin, nickel, silver, copper, gold, indium, stainless steel, chromium, titanium and the like. Examples of the metal oxide include aluminum oxide, zinc oxide, antimony oxide, indium oxide, calcium oxide, cadmium oxide, silver oxide, gold oxide, chromium oxide, silicon oxide, cobalt oxide, zirconium oxide, tin oxide. , Titanium oxide, iron oxide, copper oxide, nickel oxide, platinum oxide, palladium oxide, bismuth oxide, magnesium oxide, manganese oxide, molybdenum oxide, vanadium oxide, barium oxide and the like. These metals and/or metal oxides may be used alone or as a mixture of two or more kinds. Among these, the metal layer has at least one selected from the group consisting of indium, aluminum, chromium, gold, silver and tin, from the viewpoint that it has excellent metallic luster and that the multilayer film has excellent stretchability. It is preferable to include a seed, and more preferable to include indium. The total content of the metal and the metal oxide in the metal layer is preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 99% by mass or more, still more preferably 99% by mass or more. It is 0.99 mass% or more, and may be 100 mass %.

The thickness of the metal layer is preferably 10 to 500 nm, more preferably 30 to 300 nm, further preferably 40 to 250 nm, still more preferably 50 to 200 nm. Since the thickness of the metal layer is within such a range, the metallic-like gloss of the multilayer film is further excellent, and even if the multilayer film is stretched by vacuum pressure molding or insert molding, the beautiful metallic-like gloss can be maintained. The molded product having the multilayer film of the invention is excellent in metallic luster.

The multilayer film preferably has a base film and a metal layer in contact with each other in view of low cost and low environmental load, but may have an anchor layer between the base film and the metal layer. By having an anchor layer between the base film and the metal layer, the adhesion between the base film and the metal layer can be improved, and in the case where the adhesive layer is provided on the metal layer side of the multilayer film, The base film can be protected from the adhesive and the whitening of the base film can be suppressed. As the material of the anchor layer, for example, a two-component curable urethane resin, a thermosetting urethane resin, a melamine resin, a cellulose ester resin, a chlorine-containing rubber resin, a chlorine-containing vinyl resin, an acrylic resin, an epoxy resin, Examples thereof include vinyl copolymer resins. Examples of the method for forming the anchor layer include a gravure coating method, a roll coating method, a coating method such as a comma coating method, a gravure printing method, and a screen printing method.

The multilayer film of the present invention may consist of only the base film layer and the metal layer, but may further have layers other than the base film layer and the metal layer. Examples of the layer other than the base film layer and the metal layer include a functional layer such as a top coat layer, a hard coat layer, an anchor layer, an easily adhesive layer, a tacky adhesive layer, and a printing layer. The positions of these layers in the multilayer film are not particularly limited, but when the metal layer side of the multilayer film is attached to an adherend, the top coat layer and the hard coat layer are surfaces of the stretched film opposite to the metal layer. Is preferably provided in the. Further, the anchor layer is preferably provided between the layer of the base film and the metal layer. Furthermore, the adhesive layer is preferably provided on the surface of the metal layer opposite to the layer of the substrate film, and the easily adhesive layer is preferably provided between the metal layer and the adhesive layer. It is preferable that the multilayer film has these layers, particularly the tackiness/adhesion layer, because the stretchability of the multilayer film is improved.

As a material for the printed layer, a resin such as vinyl chloride resin, amide resin, ester resin, acrylic resin, urethane resin, vinyl acetal resin, polyester urethane resin, cellulose ester resin, or alkyd resin is used as a binder. It is preferable to use a colored ink containing a pigment or dye of an appropriate color as a colorant. Examples of the method for forming the print layer include ordinary printing methods such as an offset printing method, a gravure printing method, and a screen printing method. In particular, the offset printing method and the gravure printing method are suitable for performing multicolor printing and gradation expression. Further, in the case of a single color, a coating method such as a gravure coating method, a roll coating method or a comma coating method can be adopted. The print layer may be provided entirely or partially depending on the design to be expressed.

As the adhesive layer, a heat-sensitive or pressure-sensitive resin suitable for the base material film can be appropriately used, but one containing an acrylic resin, a styrene resin, an amide resin or the like is preferable, and one containing an acrylic resin. Is more preferable. Examples of the method for forming the adhesive layer include a gravure coating method, a roll coating method, a coating method such as a comma coating method, a gravure printing method, and a screen printing method. The thickness of the adhesive layer after drying is preferably 1 to 200 μm, more preferably 10 to 150 μm, further preferably 20 to 100 μm from the viewpoint of adhesiveness and handleability, and More preferably, it is 30 to 70 μm.

From the viewpoint of cost and surface hardness, the thickness of the multilayer film is preferably 5 to 500 μm, more preferably 10 to 300 μm, still more preferably 20 to 100 μm, still more preferably 30 to 60 μm. ..

The method for producing the multilayer film of the present invention is not particularly limited and can be produced, for example, by forming a metal layer on the substrate film as described above. The method for forming the metal layer on the base film is not particularly limited, and examples thereof include a vacuum vapor deposition method, an ion plating method, sputtering, and chemical vapor deposition. When the vacuum deposition method is used, the degree of vacuum is preferably 0.1 Pa or less, and more preferably 0.01 Pa or less, from the viewpoint of improving the thickness accuracy of the metal layer.

(Molded body)
The molded article of the present invention has the multilayer film of the present invention and an adherend. As a preferred embodiment of the molded article, the multilayer film of the present invention is provided on the surface of the adherend, and the multilayer film of the present invention is provided so that the metal layer side of the multilayer film of the present invention faces the surface of the adherend. It is more preferable to provide. Since the molded product has the multilayer film of the present invention on the surface of the adherend, it has excellent surface smoothness, surface hardness, and metallic luster. Examples of the adherend include a thermoplastic resin, a thermosetting resin, a wood base material, or a non-wood base material.

Examples of the thermoplastic resin used for the adherend include polycarbonate, polypropylene, polystyrene, polyvinyl chloride, other (meth)acrylic resins, ABS (acrylonitrile-butadiene-styrene copolymer) resins, ethylene vinyl alcohol. Examples thereof include resins, polyvinyl butyral, vinyl acetal resins, styrene thermoplastic elastomers, olefin thermoplastic elastomers, acrylic thermoplastic elastomers, and the like.

Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin and the like. Examples of the non-woody base material include a base material made of kenaf fiber and a base material made of carbon fiber.

The method for producing the molded body is not particularly limited, and examples thereof include a method of heating the multilayer film of the present invention to perform vacuum molding, pressure molding, compression molding or vacuum pressure molding on the surface of the adherend. When the bonding temperature of the multilayer film is too low, the residual stress in the substrate film may cause the multilayer film to fail to stretch during heat molding, resulting in cracking or cracking of the film. Further, if the temperature for producing the molded product is too high, the metal of the metal layer aggregates and the metallic luster disappears regardless of whitening due to shrinkage of the substrate film described later. A specifically preferable temperature range is T _C −10° C. or higher and T _C +50° C. or lower. More preferably, it is not lower than T _C +10° _{C and} lower than T _C +30° _C .
Further, a molded body can be manufactured by insert molding or injection molding simultaneous laminating method in which the multilayer film of the present invention is preformed by the above molding method, is inserted into a mold, and molten resin is injection molded on the metal layer side.

Since the multilayer film of the present invention is used as a decorative film, it is required that the multilayer film does not whiten and has a high gloss value even if heat stretching is applied during molding. As a result of diligent studies, it has become clear that in order to suppress whitening in the multilayer film as described above, it is essential to control the shrinkage ratio, and it is preferable that the adhesiveness is high. Although the mechanism of whitening is still under investigation, shrinkage of the base film occurs during heat molding, and if the adhesive force between the base film and the metal layer is lower than a certain level, peeling between the metal layer and the base film layer occurs. It is considered that whitening occurs due to visible light scattering because the metal layer is deformed and the metal layer is deformed.

(Use)
The use of the multilayer film and the molded product of the present invention is not particularly limited, and examples thereof include vehicle decorative parts such as bumpers, emblems, vehicle exteriors and vehicle interiors; building material parts such as wall materials, window films, window frames, bathroom wall materials. Household items such as vacuum cleaner housings, television housings, air conditioner housings; interior members such as kitchen doors and cover materials; ship members and the like.
Among them, the multilayer film of the present invention is excellent in punching resistance and metallic luster, so that it can be suitably used for a molded product requiring designability. In addition, the multilayer film of the present invention can be particularly suitably used as a metallic decorative film for metallic decorative applications.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to the examples below. Further, the present invention includes all modes in which the items representing the technical characteristics such as the characteristic value, the form, the manufacturing method, and the use described above are arbitrarily combined.

(Polymerization conversion rate)
A gas chromatograph GC-14A manufactured by Shimadzu Corporation was used as a column with GL Sciences Inc. Inert CAP 1 (df=0.4 μm, ID=0.25 mm, length=60 m) manufactured by Inert CAP 1 was connected, and the injection temperature was 180° C., the detector temperature was 180° C., and the column temperature was maintained at 60° C. for 5 minutes, 60 The temperature was raised from 200C to 200C at a heating rate of 10C/min, and the measurement was performed under the condition of holding at 200C for 10 minutes, and the polymerization conversion rate was calculated based on the result.

(Weight average molecular weight Mw, weight average molecular weight Mw/number average molecular weight Mn)
The chromatogram was measured by gel permeation chromatography (GPC) under the following conditions, and the value converted into the molecular weight of standard polystyrene was calculated. The baseline shows that the slope of the peak on the high molecular weight side of the GPC chart changes from zero to a positive value when the retention time is early, and the slope of the peak on the low molecular weight side is a negative value to zero when the retention time is early. It is a line connecting the points that change.
GPC device: manufactured by Tosoh Corporation, HLC-8320
Detector: Differential Refractive Index Detector Column: Two TSKgel SuperMultipore HZM-M manufactured by Tosoh Corporation and Super HZ4000 connected in series were used.
Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml/min Column temperature: 40°C
Calibration curve: Created using the data of 10 points of standard polystyrene

(Syndiotacticity (rr) in triplets display)
Using a nuclear magnetic resonance apparatus (ULTRA SHIELD 400 PLUS, manufactured by Bruker), deuterated chloroform was used as a solvent, and ¹ H-NMR spectrum was measured under the conditions of room temperature and an integration number of 64 times. From the spectrum, the area A 0 of the region of 0.6 to 0.95 ppm and the area A _Y of the region of 0.6 to 1.35 ppm when TMS was set to 0 ppm were measured, and then, the syndet of triplets was displayed. The tacticity (rr) (%) was calculated by the formula: (A ₀ /A _Y )×100.

(Glass transition temperature (Tg))
According to JIS K 7121, using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50 (product number)), the temperature was once raised to 230° C., then cooled to room temperature, and then from room temperature to 230° C. Was measured at a temperature of 10° C./min to measure a DSC curve. The midpoint glass transition temperature obtained from the DSC curve measured during the second temperature rise was taken as the glass transition temperature in the present invention.

(Haze)
The substrate film obtained in the example was cut into 50 mm×50 mm to prepare a test piece, and the haze was measured using a haze meter (SH7000, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 7136.

(Dimensional change)
A 40 mm×5 mm test piece was cut out from the multilayer film obtained in the example. Here, the longitudinal direction of the test piece was parallel to the width direction of the original film. Both ends of the test piece in the longitudinal direction were held by a pair of film chucks. At this time, the distance between the pair of film chucks was set to 24 mm. A tensile load of 2 g was applied to the multilayer film by a pair of film chucks, and this was attached to a thermomechanical analyzer (Q400EM manufactured by TA Instruments).
The length of at setting the test piece as described above, the test piece was heated at a heating rate of 2 ° C. / min to 85 ° C. from 25 ° C., immediately after reaching the 85 ° C. specimen (L _B) Was measured. Thereafter, the test piece was held at 85 ° C., measured length of the test piece immediately after lapse of 30 minutes (L _A). Then, the value as _(L A _-L B) [Unit: [mu] m] of ΔL calculated value of, and the dimensional change. If the dimensional change is positive, it is expansion, and if it is negative, it is contraction.

(Total light transmittance)
The multilayer film obtained in the example was cut into 50 mm×50 mm to prepare a test piece, and the total light transmittance was measured using a haze meter (SH7000 manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

(Punching resistance)
The multilayer film obtained in the example was cut out into a test piece of 80 mm×80 mm, and the test piece and a punching jig (Thomson blade) of 40 mm×40 mm were set in a punching device (SDL-200 manufactured by Dumbbell Co., Ltd.) and tested. Pieces were punched out to 40 mm x 40 mm. The punched test piece was evaluated as A when there was no crack (flame) of 1.5 mm or more, and when there was a crack, it was evaluated as C.

(Evaluation of gloss value)
The multilayer film obtained in the example was cut out into 100 mm×100 mm to give a test piece, which was set in a biaxial stretching birefringence measuring device (EDR, SDR-563K), temperature 140° C., stretching speed 3600%/min and area stretching. Stretching was performed under the condition that the ratio was 140%. After the test piece was stretched by the method, the appearance was evaluated as follows using an appearance analyzer (Rhopoint IQ, manufactured by Rpointpoint Instrument).
A: 20° gloss value is 1000 GU or more B: 20° gloss value is less than 1000 GU 900 GU or more C: 20° gloss value is less than 900 GU

(Adhesion)
A 125 μm-thick PET film (Toray Stock Co., Ltd.) was coated with a UV-curing adhesive (Z-773, manufactured by Aika Kogyo Co., Ltd.) on the metal surface side of the multilayer films obtained in Examples so that the thickness after drying was 5 μm. A company made product A-4100) was pasted, and UV of 2000 mJ/cm ² was irradiated from the PET film surface using a UV irradiation device (HTE-3000B manufactured by HI-TECH) to obtain a sample. A peel test was carried out on the obtained sample with a width of 25 mm to evaluate the adhesion.

(appearance)
The molded body obtained in the example was placed on a white paper (C ^2r manufactured by FUJI xerox Co., Ltd.), and the appearance was visually observed under a fluorescent lamp (200 lux).
A: No whitening, high-quality appearance B: Whitening slightly, but no loss of metallic tone C: Severe whitening, loss of metallic tone D: Film tears during molding and evaluation as a molded product is not possible

(Production Example 1) [Production of (meth)acrylic resin (A)]
The inside of the autoclave equipped with the stirrer and the sampling tube was replaced with nitrogen. To this, 100 parts by mass of distilled and purified methyl methacrylate (MMA), 2,2′-azobis(2-methylpropionitrile) (hydrogen abstraction capacity: 1%, 1 hour half-life temperature: 83° C.) 0.0052 Parts by mass and 0.225 parts by mass of n-octyl mercaptan were added and stirred to obtain a raw material liquid. Nitrogen was sent into this raw material liquid to remove dissolved oxygen in the raw material liquid.
The raw material liquid was put into a tank reactor connected to an autoclave through a pipe to a volume of 2/3. With the temperature maintained at 140° C., the polymerization reaction was first started in a batch system. When the polymerization conversion rate reached 55% by mass, while maintaining the temperature at 140°C, the raw material solution was supplied from the autoclave to the tank reactor at a flow rate that would make the average residence time 150 minutes. The polymerization reaction was switched to a continuous flow system in which the reaction solution was withdrawn from the tank reactor at a corresponding flow rate. After switching to the continuous flow system, the polymerization conversion rate in the steady state was 55% by mass.
The reaction liquid extracted from the tank-type reactor in the steady state was supplied to a multi-tube heat exchanger having an internal temperature of 230° C. at a flow rate to give an average residence time of 2 minutes and heated. Next, the heated reaction liquid was introduced into a flash evaporator to remove a volatile component containing an unreacted monomer as a main component to obtain a molten resin. The molten resin from which the volatile components were removed was supplied to a twin-screw extruder having an internal temperature of 260° C., discharged in a strand shape, and cut with a pelletizer to obtain a pellet-shaped (meth)acrylic resin (A). Table 1 shows the physical properties of the obtained (meth)acrylic resin (A).

(Production Example 2) [Production of (meth)acrylic resin (B1)]
The inside of the autoclave equipped with the stirrer and the sampling tube was replaced with nitrogen. At room temperature, 2.9 parts by mass of toluene, 0.0045 parts by mass of 1,1,4,7,10,10-hexamethyltriethylenetetramine, and 0.45 M of isobutylbis(2,6- 0.097 parts by mass of a toluene solution of di-t-butyl-4-methylphenoxy)aluminum and a solution of sec-butyllithium having a concentration of 1.3 M (solvent: cyclohexane 95% by mass, n-hexane 5% by mass). 011 parts by mass were charged. While stirring, 100 parts by mass of MMA which had been purified by distillation was added dropwise to these raw materials at 20° C. over 30 minutes. After completion of dropping, the solution was stirred at 20° C. for 90 minutes, and the color of the solution changed from yellow to colorless. The polymerization conversion rate of MMA at this point was 100%. 2.7 parts by mass of toluene was added to the obtained solution to dilute it. Then, the diluted solution was poured into 180 parts by mass of methanol to obtain a precipitate. The obtained precipitate was dried at 80° C. and 140 Pa for 24 hours to obtain a (meth)acrylic resin (B1). Table 1 shows the physical properties of the obtained (meth)acrylic resin (B1).

(Production Example 3) Methacrylic resin composition (C)
80 parts by mass of (meth)acrylic resin (A), 20 parts by mass of (meth)acrylic resin (B1), 1 part by mass of an ultraviolet absorber (LA-F70 manufactured by ADEKA), and a polymer processing aid (Mitsubishi 2 parts by weight of Metabrene P550A manufactured by Chemical Co., Ltd. is mixed by a Henschel mixer, and is kneaded and extruded by using a twin screw extruder (KZW15-45MG manufactured by Technovel Co., Ltd.) having a screw diameter of 15 mm and set to 260° C., and glass transition. Pellets of the methacrylic resin composition (C) having a temperature Tg of 122° C. were obtained.

<Example 1>
(Production of base film)
The pellet-shaped methacrylic resin composition (C) was melted at 270° C. with a φ20 mm vented single-screw extruder (manufactured by Toyo Seiki Seisaku-sho, Ltd.) to which a T-die was connected, and extruded into a sheet from a T-die having a width of 150 mm. .. The distance from the die discharge part until the molten thermoplastic resin composition comes into contact with the cast roll was 30 mm, and the extruded thermoplastic resin composition was brought into close contact with a 100 mm diameter cast roll and cooled to give a thickness of 160 μm. The original film. Subsequently, a raw film relating to a biaxially stretched birefringence measuring device (SDR-563K, manufactured by Eto Co.) was cut into 100 mm×100 mm and introduced, and preheated at 155° C. Then, the raw film was subjected to simultaneous biaxial stretching at 155° C. at a draw ratio of 4.0 times (longitudinal direction 2.0 times and width direction 2.0 times). At this time, the stretching speed was 200%/min in both the longitudinal direction and the width direction. Then, it cooled to 115 degreeC and heat-fixed for 1 minute, and obtained the 40-micrometer stretched film as a base film.

(Manufacture of multilayer film)
The substrate film thus obtained was subjected to corona treatment under the condition of 14 kV using a corona treatment device (Corona Cassener ASA-4, manufactured by Shinko Electric Instrumentation Co., Ltd.), and then a vacuum deposition device (Synchron, vacuum deposition). Using a device BMC-850CS, resistance heating method), an indium layer having a thickness of 50 nm was formed by vacuum vapor deposition to obtain a multilayer film which is a metal-like decorative film. At this time, a basket heater (92% alumina) was used for resistance heating, and indium having a purity of 99.99% and a grain size of 1 mm was used. The vapor deposition conditions were a vacuum degree of 8×10 ⁻³ Pa and a speed of 10 Å/sec. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film was observed from the side of the base film, it had a beautiful metallic luster.

(Production of molded body)
The obtained multilayer film was cut into 210 mm×300 mm to obtain a test piece. Also, a polystyrene resin clip case (manufactured by Plus Co., CP-500, width 76 mm x depth 62 mm x height 40 mm) was used as the adherend. Three-dimensional surface decorative molded (T hree dimension O verlay M ethod ) device (Fuse Vacuum Co., NGF-0406T), the adherend and the test piece according metal layer of the test piece on the convex side of the adherend They were set so as to face each other, and molding was performed under the conditions of a preheating temperature of 140° C. and a pressure difference of 300 kPa to obtain a molded body. In the molded body, the multilayer film was not broken or whitened, and the molded body had a beautiful metallic luster.

<Example 2>
A multilayer film was produced in the same manner as in Example 1 except that the thickness of the raw film was changed to 300 μm and simultaneously biaxially stretched was used as the substrate film in the production of the substrate film of Example 1. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the base film side, it had a beautiful metallic luster.

<Example 3>
A multilayer film was produced in the same manner as in Example 1 except that the stretching temperature was changed to 145° C. in the production of the base film of Example 1. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the stretched film, whitening occurred slightly, but the metallic luster was not lost.

<Comparative Example 1>
A multilayer film was produced in the same manner as in Example 1 except that the stretching ratio was changed to 6 times in the production of the base film of Example 1. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the stretched film, whitening occurred and gloss was lost in a metallic tone.

<Comparative example 2>
A multilayer film was produced in the same manner as in Example 1 except that the methacrylic resin composition (C) was changed to the (meth)acrylic resin (A) in the production of the raw film of Example 1. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the substrate film, it had a beautiful metallic luster, but the punching resistance was low and trimming after molding was difficult.

<Comparative example 3>
A multilayer film was produced in the same manner as in Example 1 except that the corona treatment was changed to non-execution in the production of the multilayer film of Example 1. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the substrate film, whitening occurred and the gloss was lost in a metallic tone.

<Comparative example 4>
A multilayer film was prepared in the same manner as in Example 1 except that a polyethylene terephthalate film (A4100, manufactured by Toyobo Co., Ltd., hereinafter PET-A) was used as the base film. The evaluation results are shown in Table 2. When the obtained multi-layer film was molded, the film was torn and it could not be evaluated as a molded product.

<Comparative Example 5>
A multilayer film was produced in the same manner as in Example 1 except that a polyethylene terephthalate film (E5100, manufactured by Toyobo Co., Ltd., hereinafter PET-B) was used as the base film. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the stretched film, the glossiness was low because the haze value of the film was high, but the metallic luster was not lost.

<Comparative example 6>
A multilayer film was produced in the same manner as in Example 1 except that an acrylic film (HI50 manufactured by Kuraray Co., Ltd., hereinafter Ac-A) was used as the base film. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the stretched film, whitening occurred slightly, but the metallic luster was not lost.

<Comparative Example 7>
A multilayer film was produced in the same manner as in Example 1 except that a polypropylene film (Pure Thermo, manufactured by Idemitsu Unitech Co., Ltd., hereinafter PP-A) was used as the substrate film. The evaluation results are shown in Table 2. When the appearance of the obtained multilayer film after molding was observed from the side of the stretched film, the glossiness was low because the haze value of the film was high, but the metallic luster was not lost.

Claims (15)

A multilayer film having a base film layer and a metal layer, having a total light transmittance of 50% or less and satisfying the following conditions.
(1) The dimensional change of the multilayer film before and after being held at 85° C. for 30 minutes is −10 μm or more. (2) When the multilayer film is isotropically biaxially stretched at a stretching temperature of 140° C. and an area stretching ratio of 140%. , 20° gloss value is 900 GU or more (3) When the multilayer film is punched using a punching device, the crack length of the test piece is 1.5 mm or less. The multilayer film according to claim 1, wherein the base film is made of an amorphous resin. The multilayer film according to claim 1, wherein the base film is made of a (meth)acrylic resin. The multilayer film according to claim 1, wherein the metal layer contains at least one selected from the group consisting of indium, aluminum, chromium, gold, silver and tin. The multilayer film according to claim 1, wherein the metal layer has a thickness of 10 to 500 nm. The multilayer film according to claim 1, wherein the base film has a thickness of 5 to 200 μm. The multilayer film according to any one of claims 1 to 6, wherein the adhesive force between the base film layer and the metal layer is 1.0 N/25 mm or more. The substrate film is the glass transition temperature _{T A} is 140 ° C. or less (meth) 99.9 to 20 wt% of an acrylic resin (A), a glass transition temperature _{T B} is _(T A + 10 ° C.) or higher The multilayer film according to any one of claims 1 to 7, which comprises a thermoplastic resin composition [C] containing 0.1 to 80% by mass of a thermoplastic resin [B]. The thermoplastic resin [B] is a polycarbonate resin, at least a structural unit derived from an aromatic vinyl compound represented by the following general formula (a) and a structural unit derived from an acid anhydride represented by the following general formula (b). And a methacrylic resin having a syndiotacticity (rr) represented by a triplet of 58% or more and a content of structural units derived from methyl methacrylate of 90% by mass or more. The multilayer film according to claim 8, comprising at least one or more thermoplastic resins selected from the group consisting of:

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group.)

(In the formula: R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group.) The multilayer film according to claim 8, wherein the base film is a stretched film. A method of manufacturing a multilayer film according to claim 10, after stretched at the glass transition temperature T _C above the temperature of the thermoplastic resin composition (C) in the production of the base film, (T _C - 25° C.) or more and a step of heat setting at a temperature lower than T _C. The method for producing a multilayer film according to claim 11, wherein the stretching ratio at the time of stretching is 1.5 to 8.0 times.
The stretch ratio means the ratio of the area after stretching to the area before stretching. The method for producing a multilayer film according to claim 11, wherein the stretching is biaxial stretching. A metallic decorative film comprising the multilayer film according to claim 1. A molded product comprising the multilayer film according to claim 1 and an adherend.