JPH05331628A - Metallic vacuum-deposited plastic film - Google Patents

Abstract

PURPOSE:To develop the metallic vacuum-deposited plastic film having excellent brightness, gloss and printability of a metallic vacuum-deposited surface by vacuum depositing metals on the surface of the plastic film consisting of a propylene resin and the hydrogenated deriv. of a styrene/butadiene copolymer. CONSTITUTION:Al, Au, Ag and other metals are melted, evaporated and are vacuum deposited on the surface of the plastic film obtd. by molding a compsn. consisting of 100 pts.wt. propylene resin, such as independent polymer of crystalline propylene or crystalline copolymer of propylene consisting essentially of propylene and ethylene or other alpha-olefin and 2 to 20 pts.wt. hydrogenated deriv. of the styrene/butadiene block copolymer having 20 to 60wt.% content of a polystyrene block. The plastic film of the metallic vacuum-deposited surface having the high strength of adhesion of the base film and the metal evaporated film, the excellent printability and laminatability on the metallic vacuum- deposited surface and the beautiful metallic gloss is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor-deposited plastic film, and more particularly, to a metal vapor-deposited film using a plastic film containing propylene resin as a main material as a base film. Adhesive strength with (hereinafter referred to as vapor deposition strength) is high, and the brightness and gloss of the metal vapor deposition surface are excellent, as well as printability on the metal vapor deposition surface and adhesion with other films (hereinafter referred to as laminating property). Also relates to excellent metallized plastic films.

[0002]

2. Description of the Related Art In recent years, metal-deposited plastic films in which metal is deposited on a plastic film under vacuum have
Utilizing its excellent decorative properties, gas barrier properties, light blocking properties, etc., it is used for a wide range of applications from existing materials such as gold and silver threads and building materials to packaging materials mainly for foods. Among them, the aluminum vapor-deposited plastic film is widely used mainly for packaging materials, and when used as a packaging material, its metal vapor deposition surface (aluminum surface)
In many cases, secondary processing such as printing or laminating with other films is performed before use.

[0003] Polypropylene film (a film containing propylene resin as a main material. Propylene resin is a homopolymer of propylene, and propylene containing propylene as a main component and ethylene or another α-olefin is a copolymer. The combination, or a mixture thereof, is a major plastic film, and the metal-deposited polypropylene-based film based on the film is used in a large amount in the above various applications. However, the conventionally known metal vapor-deposited polypropylene film is
When the vapor deposition strength is low and the metal to be vapor-deposited is aluminum, the printability on the metal vapor-deposited surface and the laminating property are remarkably poor, so it is suitable for applications requiring secondary processing such as printing or laminating on the metal vapor-deposited surface. It could not be used, which was a major obstacle to application development.

Therefore, there is a method of using a low-density polyethylene film having a high vapor deposition strength in place of the conventionally known polypropylene film. However, the film has a drawback that the surface becomes rough and thus the glossiness of the metal vapor deposition surface is lowered, and a metal vapor deposition plastic film exhibiting a beautiful metallic luster cannot be obtained.

The cause of the low vapor deposition strength of the conventionally known polypropylene film is the chemical inertness inherent in polypropylene. In addition, the cause of poor printability and laminating property on the metal vapor-deposited surface is that the neutralizing agent, slip agent, antioxidant, etc., which are added as auxiliary materials in the propylene-based resin, to the metal vapor-deposited surface of the metal-deposited plastic film This is because it will be transferred. Further, the auxiliary material that has moved to the opposite surface (the surface on which the metal has not been vapor-deposited) also comes into contact with the metal vapor-deposited surface when the film is wound into a roll and is transferred to the metal vapor-deposited surface. (JP-B-58-49574 and JP-A-59-25829)

Among the auxiliary materials, fatty acid derivatives used as a neutralizing agent, particularly higher fatty acid salts such as calcium stearate and sodium stearate, and higher fatty acid amides such as oleic acid amide, stearic acid amide and erucic acid amide are Even if the content is as small as 0.01% by weight, the wettability index of the metal vapor deposition surface (aluminum surface) should be 33 dyn / cm or less to make printing or lamination adhesion to the vapor deposition surface impossible. ..

Conventionally, various proposals have been made in order to solve such problems. For example, as a method for increasing the vapor deposition strength, a method of physically or chemically treating the film surface to roughen it, corona discharge, a gas flame and radiation irradiation to oxidize the film surface to form a film surface. Known methods include a method of imparting a polar group and a method of coating the film surface with an adhesive material. However, any of the methods of roughening or oxidizing the film surface alone is still insufficient in vapor deposition strength, and the method of coating the film surface with an adhesive material physically removes the film surface prior to coating. It is necessary to chemically or chemically pre-treat, which complicates the process and increases the cost of the metal vapor deposition film.

As a method for improving vapor deposition strength as well as printability and laminating property on a metal vapor deposition surface, a film obtained from a mixed resin prepared by blending polypropylene with polypropylene graft-polymerized with maleic anhydride is used. It is also known to use as a base film. However, in this case as well, the film cost becomes high, and the unreacted maleic acid remaining in the film and the odor of the decomposed product generated by thermal decomposition are strong, When used for food packaging, it had a drawback that an offensive odor was attached to the contents.

Further, the wetting index of the metal vapor deposition surface is lowered,
In order to improve the printability and laminating property on the metal vapor deposition surface,
The present inventors have previously disclosed in Japanese Patent Laid-Open No. 59-25829,
Propylene with MFR (melt flow rate) specified
An olefin-based resin composition for metal-deposited film, which is prepared by mixing an α-olefin copolymer and polyethylene having a specified MFR, has been proposed. However, the metal vapor-deposited plastic film obtained from the composition still has an insufficient vapor deposition strength, and when the amount of polyethylene is increased, the printability is improved but the film tends to tear.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies to solve the above-mentioned drawbacks of the prior art, and as a result, formed a composition comprising a propylene resin and a specific block copolymer. It was clarified that the above problems can be solved by using the obtained plastic film as a base film of a metal vapor deposition film, and the present invention was completed.

As is apparent from the above description, the object of the present invention is a metal vapor-deposited plastic film based on a plastic film containing a propylene resin as a main material, but has a high vapor deposition strength and a brightness on the metal vapor deposition surface. ,
It is an object of the present invention to provide a metal-deposited plastic film which is excellent in glossiness, printability and laminating property.

[0012]

The present invention has a propylene resin content of 100 parts by weight and a polystyrene block content of 2 parts.
A metal-deposited plastic film obtained by depositing a metal on the surface of a plastic film obtained by molding a composition comprising 0 to 60% by weight of a hydrogenated derivative of a styrene-butadiene block copolymer and 2 to 20 parts by weight. Is.

The propylene resin used in the present invention is
It is a crystalline propylene homopolymer, a crystalline copolymer of propylene containing propylene as a main component and ethylene or another α-olefin, or a mixture thereof. Of these, a crystalline ethylene / propylene copolymer and a crystalline propylene / butene-1 copolymer containing 80 to 98% by weight of a propylene component and having a crystalline melting point (hereinafter referred to as Tm) in the range of 115 to 150 ° C. Polymer, crystalline ethylene-propylene-butene-1 terpolymer (in this case ethylene:
The butene-1 content ratio is preferably 10: 1 to 1:15), or a mixture thereof has a vapor deposition strength of a film obtained from a composition obtained by mixing these with a hydrogenated derivative of a block copolymer described below. It is particularly desirable because it has the effect of increasing the height and improving impact resistance and heat sealability. The homopolymer or copolymer can be obtained by polymerizing each monomer in the presence of, for example, a Ziegler-Natta type catalyst.

Here, Tm is an endothermic curve accompanying melting of a crystalline polymer obtained by heating a 10 mg sample at a rate of 10 ° C./min in a nitrogen atmosphere using a scanning differential calorimeter. Say peak temperature. In the case of a crystalline copolymer containing propylene as a main component, T increases as the content of ethylene or α-olefin, which is a comonomer component, increases.
m decreases. For example, in the case of a crystalline ethylene / propylene random copolymer, the Tm becomes 150 ° C. or lower when the ethylene content exceeds about 2.5% by weight, though it varies slightly depending on the randomness of the copolymer. It should be noted that a polymer having a plurality of Tm's can be obtained by carrying out the copolymerization in multistage polymerization in two or more stages under different polymerization conditions, and such a polymer can also be used in the present invention. Is preferably 150 ° C. or lower.

The hydrogenated derivative of a styrene / butadiene block copolymer (hereinafter referred to as SEBS) used in the present invention has an unsaturated bond of a block copolymer in which polystyrene blocks are bonded to both ends of a polybutadiene block. Obtained by hydrogenation.

The reason why the content of the polystyrene block which is a constituent of SEBS in the present invention is limited to 20 to 60% by weight is that the content of the polystyrene block is less than 20% by weight, the vapor deposition strength and the printing on the metal vapor deposition surface. sex,
When the effect of improving the laminating property is not obtained and the content of the polystyrene block exceeds 60% by weight, the transparency and surface smoothness of the plastic film are deteriorated, and a metal vapor deposition film having a beautiful metallic luster can be obtained. Because it will not be possible.

In the composition of the composition, 2 to 2 SEBS to be added to 100 parts by weight of the propylene resin is used.
The reason for limiting the amount to 0 parts by weight is that if the amount is less than 2 parts by weight, the effect of improving the vapor deposition strength, the printability on the metal vapor deposition surface and the laminating property is poor, and if the amount exceeds 20 parts by weight, the film surface is roughened to give a beautiful metallic luster. This is because a metal-deposited plastic film having a feeling cannot be obtained.

In the composition used in the present invention, an antioxidant and, if necessary, an auxiliary material such as an inorganic filler, a lubricant, an antiblocking agent and a high-density polyethylene are added within a range not impairing the purpose of the present invention. Although it can be contained as appropriate, it is desirable not to use fatty acids and derivatives containing a fatty acid-forming group in order not to deteriorate the adhesiveness of the metal vapor deposition film, the printability on the metal vapor deposition surface, and the laminating property.

The antioxidant is preferably phosphorus-based or phenol-based having a molecular weight of 500 or more. In particular,
Tetrakis- [methylene-3- (3 ', 5'-di-t-
Butyl-4'-hydroxyphenyl) propionate]
Methane, 1,3,5-trimethyl-2,4,6, -tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 1,3,5-tris (4-t-butyl-)
3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 6- [4-hydroxy-3,5-di-t-butylamino) -2,4-bisnoctylthio-1,3,3
5-triazine, 1,1,3-tris (2-methyl-4)
-Hydroxy-5-t-butylphenyl) butane, tris (3,5-di-t-butyl-4-hydroxyphenyl) isocyanurate, tetrakis (2,4-di-t-)
Butylphenyl) 4,4'-biphenylene-diphosphonite and the like.

When the antioxidant is used alone or in combination of two or more kinds, and added in an amount of 0.03 to 0.30 part by weight to 100 parts by weight of the propylene resin, it is extremely effective for the thermal stability of the film. ..

The inorganic filler used in the present invention includes:
Any of calcium carbonate, silica, clay, talc, hydrotalcite, zeolites and the like can be used.

Further, as the high-density polyethylene used in the present invention, the density of the high-density polyethylene is 0.93 g.
/ Ml or more, and the ratio of the melt flow rate (MFR-PP) of the propylene resin and the melt flow rate (MI-PE) of the high-density polyethylene is 0.5 ≦ (MI-PE) / (MFR-PP). ) Is particularly effective for obtaining a metal vapor-deposited plastic film having excellent printability and laminating property on a metal vapor-deposited film, in addition to the improvement of vapor-deposition strength and a beautiful metallic luster which are the subjects of the present invention. is there.

The method of mixing SEBS and the above-mentioned auxiliary materials with the propylene-based resin is not particularly limited as long as it is a method of uniformly dispersing the same, but a ribbon blender,
A method of mixing with a Henschel mixer (trade name) or the like and melt-kneading the mixture with an extruder or the like is desirable. The polypropylene film used in the present invention can be obtained from the above composition by a usual T-die method or inflation method. The film may be a uniaxially or biaxially stretched film, or may be an unstretched film.

In the present invention, in addition to the single-layer plastic film as described above, a composite film in which a plurality of films are laminated with one surface or both surfaces of the plastic film as a surface layer can be used as the base film. In this case, it goes without saying that the vapor-deposited metal film is formed on the plastic film, that is, the plastic film obtained from the composition forming the surface layer. When the metal-deposited plastic film thus obtained is expressed with reference to the single-layer metal-deposited plastic film, it has a constitution in which a plurality of monolayer films are laminated as the outermost layer with the vapor deposition surface facing outward. ing. The case of a monolayer film will be described below, but the same applies to the case of a composite film.

The plastic film obtained from the above composition can be directly subjected to metal vapor deposition as a base film, but surface treatment such as corona discharge treatment or flame treatment in air or in a special gas atmosphere such as nitrogen or oxygen. Thus, the wettability and adhesiveness of the film surface may be improved, and the adhesiveness may be further improved before use.

A known general vacuum deposition method for depositing a metal on the surface of a plastic film is as follows. That is, the degree of vacuum in a vacuum vapor deposition apparatus provided with a pay-out section, a metal vapor deposition section and a winding section of a plastic film (usually a roll-shaped long film) is set to 13.3 mPa or less, and aluminum or the like is desired in the apparatus. The metal is heated to dissolve and evaporate the metal, and the metal is continuously vapor-deposited on the unwound film surface and wound. The method using such a vacuum vapor deposition apparatus is a batch method, and since it is necessary to improve productivity, recently, one film roll has a width as wide as 2 m or more and a length of 10,000 to 20,000 m as wide as possible. Since the length of the film has been increased, the requirements for high-speed vapor deposition property and winding shape of the film for metal vapor deposition are becoming more severe.

There are various metal vapor deposition methods other than the vacuum vapor deposition method. For example, a sputtering vapor deposition method and an ion plating method, which utilize a phenomenon that a metal forming a cathode scatters when discharged in a vacuum, are shown.

Aluminum is the most common metal to be deposited, but gold, silver, copper, nickel, chromium,
Examples thereof include germanium, selenium, titanium, tin and zinc.

The thickness of the metal vapor deposition film is usually in the range of 5 to 80 nm, and the metal vapor deposition can be performed not only on the entire surface of the base film, on one side, but also on partial vapor deposition. Further, a top coat may be further applied on the metal vapor deposition film for coloring and protection.

[0030]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The methods for measuring the physical properties shown in Examples and Comparative Examples and the criteria for evaluation are as follows.

(1) Haze: ASTM D
According to 1003, the value (unit:%) measured by stacking four undeposited films is shown as haze. The smaller this value, the better the transparency. (2) Adhesiveness of aluminum vapor deposition film: Surlyn film (ionomer manufactured by Tama Poly Co., Ltd.) is overlaid on the metal vapor deposition film of metal vapor deposition plastic film, and the width is 10 mm under the conditions of a sealing temperature of 120 ° C., a sealing pressure of 196 kPa, and a sealing time of 1 second.
A 15 mm seal was performed, and 90 degree peel strength was measured by a tensile tester. (Unit: N / 15 mm) (3) Metallic gloss: According to the specular glossiness method of ASTM D 523, the glossiness measured at a sensitivity of 1/20 was shown. The test piece was a metal-deposited plastic film having aluminum vapor-deposited on one surface, and light was applied to the plastic surface of the test piece at an indicated angle of 20 °, and the measured value was 70% or more. (4) Wetting index: Wetting index was measured by a method according to JIS K 6758. (Unit: dyn / cm) (5) Printability on metal deposition surface: Two metal deposition plastic films with aluminum deposited on one surface are prepared,
The metal vapor-deposited surface and the non-vapor-deposited surface were overlapped with each other under a load of 4.12 kPa, left for 72 hours in an atmosphere having a temperature of 40 ° C. and a relative humidity of 95%, and then peeled off at room temperature to be in contact with the metal vapor-deposited surface. The wetting index was measured. In order to evaluate good printability, the wetting index is 35 dyn / cm or more, preferably 37
Requires dyn / cm or more. The printability on the metal vapor deposition surface was ranked as shown in Table 1 from the wetting index.

[0032]

[Table 1]

(6) Laminating property: A biaxially stretched polypropylene film (20 μm) is bonded to the metal vapor-deposited surface of a metal vapor-deposited plastic film having aluminum vapor-deposited on one side by using an adhesive for dry lamination, and 60 ° C.
After aging it for 3 days to completely dry the adhesive,
At room temperature, the metal vapor deposition film and the biaxially stretched film (20 μm) were peeled by 90 ° with a tensile tester, and those having a measured value of 1.96 N / 15 mm or more were evaluated as ◯.

Examples 1-5, Comparative Examples 1-6 Crystalline ethylene / propylene / butene-containing 2.5% by weight of ethylene and 4.5% by weight of butene-1.
1 terpolymer and melt flow rate (MFR-
PP) 6 g / min (230 ° C.) and Tm 140 ° C. 100 parts by weight of propylene resin, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4 ′) as an antioxidant. 0.1 part by weight of -hydroxyphenyl) propionate] methane was added, blended and pelletized using an extruder. With respect to 100 parts by weight of the pellets, various SEBSs having different contents of styrene polymer blocks shown in Table 2 were dry blended in a blender in an amount of parts by weight shown in Table 2, and the resulting composition was extruded with an extruder having a diameter of 65 mmφ. And extruded at a melting temperature of 220 ° C using a T-die and rapidly cooled with an air chamber and a cooling roll having a surface temperature of 30 ° C to obtain a plastic film, and immediately one side of the film was subjected to corona discharge treatment so that the wetting index was 40 dyn / cm. The film was wound up while being rolled to obtain a roll-shaped plastic film having a thickness of 25 μm and a width of 60 cm. Width of this plastic film is 50 cm using a slitter
After cutting it into a continuous film, it is set as a base film in a continuous vacuum evaporation apparatus, and while continuously feeding out the film, under vacuum of 6.66 mPa, aluminum is vapor-deposited on the corona-treated surface of the film and wound up, and metal evaporation is performed. A single-sided aluminum vapor-deposited plastic film having a film thickness of about 35 nm (within ± 1.5 nm) was obtained in a roll shape having a length of 2000 m. Test pieces were prepared using the plastic films and metal-deposited plastic films obtained in each of Examples and Comparative Examples, and the performance of each film was evaluated according to the above evaluation method. The results are shown in Table 2.

[0035]

[Table 2]

Example 6 Instead of the crystalline ethylene / propylene / butene-1 terpolymer used as the propylene resin in Example 1, a crystalline ethylene / propylene copolymer (MFR) was used.
-One side of which a plastic film was molded according to Example 1 except that PP was 7 g / min (230 ° C) and Tm was 150 ° C, and the film was used as a base film according to Example 1 An aluminum deposited plastic film was obtained. Test pieces were prepared using the obtained plastic film and metal-deposited plastic film, and the performance of each film was evaluated according to the above evaluation method. The results are shown in Table 2.

Example 7 A crystalline homopolymer of propylene (MFR-PP) was used in place of the crystalline ethylene / propylene / butene-1 terpolymer used as the propylene resin in Example 1.
Of 8 g / min (230 ° C.) and Tm of 162 ° C.) was used to mold a plastic film in accordance with Example 1, and in accordance with Example 1, the film was used as a base film for single-sided aluminum vapor deposition. A plastic film was obtained. Test pieces were prepared using the obtained plastic film and metal-deposited plastic film, and the performance of each film was evaluated according to the above evaluation method. The results are shown in Table 2.

As is clear from Table 2, the plastic film obtained from the composition defined in the present invention and the metal vapor-deposited plastic film thereof are excellent in all properties, whereas the film of the comparative example has any property. It turns out that is significantly inferior.

[0039]

The metal-deposited plastic film according to the present invention uses a plastic film containing a propylene-based resin as a main material as its base film, but by adding a specific amount of a specific SEBS to the base film. It can be used widely for packaging, decoration, etc., because it can improve the adhesive strength between the metal vapor deposition film and the metal vapor deposition film, the printability on the metal vapor deposition surface, and the laminating property, and also maintain a beautiful metallic luster on the metal vapor deposition surface. I can.

Claims (1)

[Claims] 1. A hydrogenated derivative of a styrene / butadiene block copolymer having a content of propylene resin of 100 parts by weight and polystyrene block of 20 to 60% by weight.
A metal-deposited plastic film obtained by depositing a metal on the surface of a plastic film obtained by molding a composition comprising 20 parts by weight.