JPH03297639A - Plastic film with metal vapor-deposited thereon - Google Patents

Abstract

PURPOSE:To obtain the title film which is large in adhesive strength of a vapor- deposited film and excellent in brightness and glossiness on the surface with metal vapor-deposited thereon by mixing the specified amount of thermoplastic urethane elastomer with polypropylene-based resin and molding the mixed composition to obtain a plastic film and vapor-depositing metal on the surface of this plastic film. CONSTITUTION:A plastic film with metal vapor-deposited thereon is obtained by molding composition consisting of 100 pts.wt. polypropylene-based resin and 1-20 pts.wt. thermoplastic urethane elastomer and vapor-depositing metal on the surface of this obtained plastic film. Further this elastomer is condensate of alicyclic isocyanate and thermoplastic urethane elastomer is utilized which has 5000-100000 weight mean molecular weight. The polypropylene-based resin is a crystalline propylene homopolymer, a crystalline copolymer which contains propylene as a main component and is formed of propylene and ethylene or the other alpha-olefine or the mixture thereof.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a metal-deposited plastic film, and more specifically, a metal-deposited film based on a plastic film made of polypropylene resin as the main material. This invention relates to a metal-deposited plastic film that has high adhesive strength between a base film and a vapor-deposited film, and has excellent brightness and gloss on a metal-deposited surface.

[Prior art] In recent years, metallized films have been utilized for their excellent decorative properties, gas barrier properties, light blocking properties, etc., and have been used mainly for food applications, from existing materials such as gold and silver threads and building materials. Its uses are expanding to a wide range of packaging materials.

In particular, aluminum vapor-deposited films are widely used mainly for packaging materials, and in most cases, the vapor-deposited surface (aluminum surface) is printed or laminated with other films.

By the way, polypropylene resin film (polypropylene resin here refers to propylene homopolymer as well as main components of propylene and ethylene or other α-
(meaning a copolymer with olefin) is one of the major plastic films.

Conventionally, metal-deposited polypropylene films having a polypropylene film as a base film have been used in large quantities for the above-mentioned purposes.

However, conventionally known metal-deposited polypropylene films have low adhesion strength between the base film and the deposited film, that is, deposition strength, and when the metal to be deposited is aluminum, the printability of the deposited surface and the adhesion with other films ( The laminability (hereinafter sometimes referred to as "laminability") is extremely low, making it unusable for applications that require printing or laminating on the vapor-deposited surface, which has been a major hindrance in the development of applications.

Furthermore, as an issue with other resins that should be referred to, in the case of low-density polyethylene plastic films with strong vapor deposition strength, the film surface becomes rough and the gloss of the metal vapor-deposited surface is low, giving it a beautiful metallic luster. It was not possible to obtain a metallized plastic film.

The reason for the low vapor deposition strength of polypropylene resin films is the inherent chemical inertness of polypropylene.

In addition, the cause of poor printability and lamination properties on the vapor-deposited surface is the neutralizing agent added to the polypropylene resin,
Slip agents, antioxidants, etc. migrate to the surface, pass through the vapor deposited layer and ooze out on the vapor deposition side, and are transferred to the vapor deposition surface on the opposite side when the material is rolled up ( Japanese Patent Publication No. 58-49574 and Japanese Patent Publication No. 59-258
(See No. 29).

To further explain the latter cause, among additives, fatty acid conductors used as neutralizing agents, especially higher fatty acid salts such as calcium stearate and sodium stearate, and higher fatty acids such as oleic acid amide, stearic acid amide, and erucic acid amide, etc. Even when the content of fatty acid amide is as small as 0.01% by weight, it lowers the wetting index of the vapor-deposited surface (aluminum surface) to 336yn 7cm or less, making printing and lamination adhesion to the vapor-deposited surface impossible. becomes possible.

Conventionally, various proposals have been made to solve these problems.

For example, methods for increasing the deposition strength include methods of physically or chemically roughening the film surface, methods of oxidizing the film surface by corona discharge, gas flame, radiation irradiation, etc. to impart polar groups, or A method of coating a film surface with an adhesive material is known.

However, when using either method of roughening or oxidizing the film surface, the strength of the vapor deposition is still insufficient, and the method of coating the film surface with an adhesive material requires pretreatment of the film surface physically or chemically prior to coating. This has the disadvantage of complicating the process and increasing the cost of the deposited film.

In addition, as a method to improve the vapor deposition strength as well as the printability and lamination properties of the vapor-deposited surface, we used a film obtained from a mixed polymer in which polypropylene was blended with grafted polypropylene, which is obtained by graft polymerizing maleic anhydride etc. to polypropylene, as a base film. It is also known to do so (see JP-A-50-61469 and JP-B-Sho 58-49574).

However, in this case as well, the cost of the film increases as described above, and the odor is strong due to the unreacted maleic acid remaining in the film and the decomposition products generated by thermal decomposition, and when used for food packaging, the odor transfers to the contents. There was a serious drawback.

The inventors of the present application previously proposed a polyolefin resin composition for metal deposited films, which is a combination of a specific propylene/α-olefin copolymer and a specific polyethylene, in JP-A-9-251129. This method uses metal (
This is an extremely useful method that prevents a decrease in the wettability index of the aluminum (aluminum) surface, and is excellent in blocking resistance, slipping property, and rigidity.

However, the vapor deposition strength of the metallized film obtained by molding and processing this composition is still insufficient, and when the amount of polyethylene added to the composition increases, the film tends to tear, and the printability of the film is poor. Although this has been sufficiently improved, the deposition strength has not been improved to the extent that it can solve the problem of bag breakage at the heat-sealed portion of laminated bags.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned drawbacks of the prior art, and although it is a metal vapor deposited film based on a plastic film whose main constituent material is polypropylene resin, the adhesion of the vapor deposited film is The objective is to provide a material with high strength and excellent brightness and gloss on the metal-deposited surface.

As a result of various studies, the present inventors have found that the above problems can be solved by using a plastic film obtained by molding a composition obtained by mixing a specific thermoplastic urethane elastomer with a polypropylene resin as a base film. The present invention was completed.

[Means to solve the problem] The present invention has the following configurations (1) and (2).

(1) A metal-deposited plastic film obtained by vapor-depositing a metal on the surface of a plastic film obtained by molding a composition comprising 1001 parts of a polypropylene resin and 1 to 20 parts by weight of a thermoplastic urethane elastomer.

(2) The metal-deposited plastic film according to item (1), which is made of a thermoplastic urethane elastomer that is a condensation product of alicyclic isocyanate and has a weight average molecular weight of 5,000 to 100,000.

The present invention will be explained in detail below.

The present invention is a metal-deposited plastic film in which a metal is deposited on a plastic film obtained by molding a composition comprising 100 parts by weight of a polypropylene resin and 1 to 20 parts by weight of a thermoplastic urethane elastomer.

The vapor deposited film formed on the vapor deposition surface is usually only on one side, but depending on the application, it may be formed on both sides.Furthermore,
The present invention also includes a metal-deposited plastic film having a structure in which the above metal-deposited plastic film has its vapor-deposited surface on the outside and a plurality of single-layer films are laminated on the inside.

The polypropylene resin used in the present invention is a crystalline propylene homopolymer, a crystalline copolymer of propylene containing propylene as a main component and ethylene or other α-olefin, or a mixture thereof.

The above-mentioned homopolymers and copolymers can be obtained, for example, by polymerizing the respective polymers in the presence of a Ziegler-Natsuter type catalyst. Among these, it contains 80 to 98% by weight of propylene component and has a crystal melting point (Tm) of 1.
Crystalline ethylene-propylene copolymer, crystalline propylene-butene-1 copolymer in the range of 15 to 150°C,
Crystalline ethylene-propylene-butene-1 terpolymer (in this case, the content ratio of ethylene:butene-1 is 10:1 to
1:15), or a mixture thereof, the film obtained from the composition obtained by mixing these and the thermoplastic urethane elastomer described later has excellent adhesion to the deposited film, as well as impact resistance and heat sealability. It is particularly desirable because it is excellent in

Here, the crystal melting point (TI) is the peak of the endothermic curve accompanying the melting of the crystal obtained by heating a 10 mg sample at a rate of 10°C/min in a nitrogen atmosphere using a scanning differential calorimeter. Say the temperature.

In the case of a crystalline copolymer containing propylene as a main component, Tl11 decreases as the content of ethylene or α-olefin as a comonomer component increases.

For example, in the case of a crystalline ethylene-propylene random copolymer, if the ethylene content exceeds approximately 2.5% by weight, the temperature will be 150° C. or lower, although it varies slightly depending on the randomness of the copolymer.

Incidentally, by changing the polymerization conditions and performing copolymerization in two or more stages, it is possible to obtain a polymer having a plurality of Tl11s, and such polymers can also be used in the present invention, but in this case as well, the main It is desirable that the peak is 150°C or less.

The thermoplastic urethane elastomer used in the present invention is preferably obtained by condensation of an alicyclic isocyanate and a diamine. Similarly, aliphatic isocyanates and diamines,
Thermoplastic urethane esters can also be obtained using aromatic isocyanates and diamines, and although the use of these resins improves the strength of vapor deposition, the compatibility with polypropylene resins deteriorates and the film surface becomes rough. , the gloss layer of the resulting metal-deposited film will be significantly impaired.

The reason why the weight average molecular weight of the thermoplastic urethane elastomer in the present invention is limited to s,ooo~100,000 is that if the weight average molecular weight is less than 5,000, the thermoplastic urethane elastomer bleeds out from the film surface, and the bleed product is The problem is that it is transferred to a metallized film, making it impossible to obtain a film with beautiful metallic luster.

Moreover, if the weight average molecular weight exceeds 100,000, the compatibility with the polypropylene resin will deteriorate, and the glossy layer will be impaired.

1 In addition, in the composition of the composition, polypropylene resin 1
00 parts by weight of thermoplastic urethane elastomer
The reason for limiting the amount to 20 parts by weight is that if it is less than 1 part by weight, no improvement effect on the deposition strength will be observed, and if it exceeds 20 parts by weight, compatibility will deteriorate.

The composition used in the present invention optionally contains an antioxidant,
Inorganic fillers, lubricants, anti-blocking agents, high-density polyethylene, etc. can be contained as appropriate within the quantitative range that does not impair the purpose of the present invention, but the adjacency of the vapor deposited film, the printability of the vapor deposition surface, the vapor deposition In order not to reduce the lamination properties represented by the lamination strength after laminating the film, it is preferable not to use a fatty acid or a starting material containing a fatty acid-forming group.

Particularly desirable additives that can be added to the film composition include phosphorus and phenol antioxidants having a molecular weight of 500 or more, inorganic fillers, and high-density polyethylene.

As shown in JP-A No. 59-25.829, for example, tetrakis-[methylene to 3-(3°, 5"-di-t-
Butyl-4°-hydroxyphenyl)propionate comethane, etc., used alone or in combination of two or more, 0.03 to 3 parts by weight per 100 parts by weight of polypropylene resin.
Add 0 parts by weight.

Addition of these antioxidants is extremely effective in improving the stability of the composition during film formation and film use.

Further, as the inorganic filler, calcium carbonate, silica, clay, talc, hydrotalcite, zeolites, etc. can be used.

Furthermore, high-density polyethylene has a density of 0.93 or more and a polypropylene resin melt flow rate (VF
R-PP) and the melt flow rate (Ml-PE) of the high-density polyethylene resin is 0.5≦MI-PE
/ MFR-PP is particularly effective because it can form a vapor-deposited film with excellent slip properties and anti-blocking properties, in addition to improving the vapor deposition strength and creating a beautiful glossy layer, which are the goals of the present invention.

The above-mentioned additives may be added to the polypropylene resin by any method as long as they can be uniformly dispersed, but they may be mixed using a ribbon blender, Henschel mixer (trade name), etc., and the mixture may be mixed using an extruder, etc. A method of melting and kneading is desirable.

The polypropylene film used in the present invention can be obtained from the above-mentioned composition by a conventional T-die method or an inflated dye method. Not only these -axially or biaxially stretched films, but also unstretched films can be used as the base film.

Further, in the present invention, in addition to the single-layer plastic film as described above, it is also possible to form a plurality of films using this plastic film as a surface layer on one or both sides.

In this case, it is a matter of course that the metal vapor-deposited film is formed on the plastic film, that is, the plastic film obtained from the composition forming the surface layer.

The metal-deposited brass film obtained in this way is expressed based on the single-layer metal-deposited brass film as the outermost layer with the metal-deposited surface facing outward. The structure is as follows.

The method for depositing metal onto a base film will be described below in the case of a single layer film, but this method will be similarly applied to the case of a composite film.

The brass film obtained from the composition can be directly subjected to metal vapor deposition, but corona discharge treatment in air or in a special gas atmosphere such as nitrogen or oxygen,
The film may be used after surface treatment such as flame treatment to improve the wettability of the film surface and further improve the adhesion.

A known general vacuum deposition method for applying metal vapor deposition to a long plastic film (usually in the form of a roll) is as follows.

That is, the unwinding part of the roll film, the vapor deposition part,
And the degree of vacuum in the vacuum evaporation apparatus equipped with the winding part is 10-
Torr or less, a desired metal such as aluminum is heated in a container or in the form of a filament in this device to melt and evaporate the metal, and vapor deposition molecules are continuously vaporized on the surface of the unrolled film and wound. take.

The method of using such vacuum evaporation equipment is a batch type, and it is necessary to improve productivity. Therefore, the requirements for high-speed deposition, roll shape, etc. of the raw film for deposition have become more severe.

There are various deposition methods other than the vacuum deposition described above. Examples include sputtering deposition and ion blating, which utilize the phenomenon in which metal constituting the cathode scatters when discharged in a vacuum.

The most common metal to be vapor-deposited is aluminum, but other metals such as gold, silver, copper, nickel, chromium, germanium,
Examples include selenium, titanium, tin, and zinc.

The thickness of the metal vapor deposited layer is usually in the range of 50 to 800 angstroms, and can be deposited not only on the entire surface, on one side, but also partially. Additionally, a top coat can be applied to the vapor-deposited surface for coloring and protection.

〔Example〕

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

(1) Weight average molecular weight
A GPC150C model (manufactured by Er's) was used.

The measurement temperature was 25°C, and tetrahydrofuran was used as the mobile phase.

(2) Haze: 357MD 1003, undeposited film
The value (unit: %) measured by stacking the sheets is shown as the haze of 4 sheets. The smaller this value is, the better the transparency is.

(3) Adhesion of aluminum vapor-deposited film: Surlyn film (ionomer manufactured by Tamabori Co., Ltd.) was layered on the vapor-deposited film side of the vapor-deposited film, and the sealing temperature was 120°C and the sealing pressure was 2.0kg7cm2. A seal with a width of 10aus x 15m+* was performed with a sealing time of 1.0 seconds, and 9
The 0 degree peel strength was measured using a tensile tester.

(Unit: H'g/15mm) (4) Metallic gloss: Based on the specular gloss method of ^STM D 523, sensitivity 1/
It is expressed as a gloss level measured at 10. The indicated angle is measured at 20 degrees, and an angle of 70 or more is considered good.

Examples 1 to 5, Comparative Examples 1 to 7 A crystalline ethylene-propylene-butene-1 terpolymer containing 2.5% by weight of ethylene and 4.5% by weight of butene-1, with a melt flow rate ( VFR-PP) is 6.0
, tetrakis-[methylene-3-
(3',S'-di-t-butyl-4'-hydroxyphenyl)propionate comethane (0.10 parts by weight) was added, and thermoplastic urethane elastomers and various condensates of various molecular weights shown in Table 1 were heated. A plastic urethane elastomer was blended in the parts by weight shown in Table 1 and made into pellets using an extruder.

The obtained pellet was transferred to an extruder with a diameter of [15 mmφ] and a T
9 Extruded using a die at a melting temperature of 220°C, rapidly cooled in an air chamber and a cooling roll with a surface temperature of 30°C to form a plastic film, and immediately subjected to corona discharge treatment on one side of this film to a wetting index of 40 dyn/Cm. Unroll it while applying, thickness 25μ, width fioc + a
It was made into a roll-shaped plastic film. This plastic film was cut to a width of 50cm using a slitter, and then set as a base film in a continuous vacuum evaporation device, and the corona-treated surface of the film was exposed to a vacuum of 5 x 10-' Torr while continuously feeding out the film. At the bottom, aluminum was deposited and rolled up to obtain a single-sided aluminum-deposited brass film with a thickness of about 350 angstroms (within ±15 angstroms) in the form of a roll with a length of 2.000 mm.

Table 1 shows the properties of the plastic films and metallized films obtained in each Example and Comparative Example.

Example 6 In Example 1, a crystalline ethylene-propylene copolymer (MF
A plastic film and a roll-shaped single-sided aluminum-deposited plastic using the slit film as a base film were obtained in the same manner as in Example 1 except that R-PP (R-PP 7,71150°C) was used.

Its characteristics are shown in Table 1.

Table 1 Example 7 In Example 1, a crystalline homopolymer of propylene (MFR-PP 8.
A plastic film and a roll-shaped single-sided aluminum-deposited plastic using the slit film as a base film were obtained in the same manner as in Example 1, except that a plastic film (Tm 162° C.) was used.

Its characteristics are shown in Table 1.

As is clear from Table 1, the plastic film obtained from the composition defined in the present invention and its metallized film have excellent properties, but the films of the comparative example have significantly poor properties. It turns out that it is inferior.

[Effects of the Invention] Although the metallized plastic film according to the present invention uses a plastic film mainly made of polypropylene resin as its base film, by blending a specific amount of thermoplastic urethane distomer, It has adhesive strength between the base film and the vapor-deposited film and a beautiful metallic luster on the vapor-deposited surface, and can be used more widely and in large quantities for packaging, decoration, etc.

that's all

Claims (2)

[Claims] (1) A metal-deposited plastic film obtained by vapor-depositing a metal on the surface of a plastic film obtained by molding a composition consisting of 100 parts by weight of a polypropylene resin and 1 to 20 parts by weight of a thermoplastic urethane elastomer. (2) The metal-deposited plastic film according to claim (1), comprising a thermoplastic urethane elastomer which is a condensation product of alicyclic isocyanate and has a weight average molecular weight of 5,000 to 100,000.