JPH0813894B2 - Polypropylene film for metal deposition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene film for metal vapor deposition having improved adhesion to other materials such as high metal vapor deposition strength, and more specifically to a specific resin. The present invention relates to a polypropylene-based film for metal vapor deposition, which has excellent metal vapor deposition power and stability due to the addition of additives, as well as excellent surface brilliance, and excellent printability and adhesiveness for lamination with other films. .

[Problems to be Solved by Prior Art and Invention]

Conventionally, polypropylene films have been used as packaging materials because of their excellent transparency, mechanical strength, heat resistance and dimensional stability.

Furthermore, the metal-deposited polypropylene film obtained by vapor-depositing a metal on the surface of this polypropylene film has the same luster as metal and has excellent commercial value, good gas barrier property, and excellent light shielding property. It is widely used as a food packaging material and building material in place of aluminum foil. It is usually used by printing or laminating another substrate on the surface of the metal vapor deposition film.

However, unlike PET (polyethylene terephthalate) etc., polypropylene itself does not have polar groups in the polymer itself, so metal vapor deposition properties, adhesion with other resins, and secondary processability such as printability are not good, and polypropylene is still insufficient. It is in a situation where it cannot be put to practical use.

That is, the metal vapor deposition strength is weak, and the wetting index (according to JIS K 6768) of the metal surface after vapor deposition is significantly decreased with time. The reason for this is that additives such as lubricants, hydrochloric acid scavengers, antioxidants, and antistatic agents that are added to polyolefins bleed out on the surface over time, resulting in a decrease in vapor deposition strength. It is believed that the additive that bleeds out when left to stand is transferred and transferred to the metal vapor deposition surface to form a thin film on the surface, thereby lowering the wetting index.

Various methods have been proposed to solve these problems. That is, an anchor coating method of surface treatment with chemicals, a method of blending a modified resin such as ethylene / α-olefin copolymer, a surface activation method of corona discharge treatment, or a total amount of additives of 0.2% by weight or less. (JP-A-56-167732) and the like.

The anchor coating method is usually a method of etching the surface with a chemical such as sulfuric acid-chromate to improve the adhesive strength, but it is economical because it consumes chemicals, costs equipment, and does not allow high-speed processing. There are drawbacks.

In the method of blending the modified resin, when the blending amount is increased, the surface luster becomes worse and the metal vapor deposition power is insufficient.

The corona discharge treatment method has no effect when the treatment is weak, and when the treatment is strong, the additive easily bleeds out over time, and the vapor deposition power gradually decreases even if the metal vapor deposition power immediately after the treatment is good.

The method in which the total amount of additives is 0.2% by weight or less does not decrease the metal deposition power with time, but cannot decompose the film due to the decomposition of the polymer during the molding process, and the film formability due to poor lubricity is poor. There are drawbacks such as.

[Means for solving problems]

Therefore, the inventors of the present invention have conducted diligent research in order to eliminate such defects, and as a result, ethylene / α-
After forming a composition containing a resin containing an olefin copolymer and a specific amount of an organic additive and an inorganic additive, by corona discharge treatment, the metal vapor deposition power and surface brilliance are extremely excellent and printing is possible. It was found that a polypropylene-based film for metal vapor deposition, which is excellent in the adhesiveness and the adhesiveness of lamination with other films, can be obtained, and the present invention has been completed based on such findings.

That is, the present invention relates to (A) polypropylene 99 to 60% by weight and (B) density 0.86 to 0.91 g / cm ³ of ethylene / α-.
Resin component 100 consisting of 1 to 40% by weight of olefin copolymer
A composition containing 0.3 part by weight or less of (C) an organic additive and 0.01 to 2 parts by weight of an inorganic additive selected from (D) silicas, zeolites, and hydrotalcites per part by weight. The present invention provides a polypropylene film for metal vapor deposition, which is formed by corona discharge treatment after film formation.

The polypropylene (A) used in the present invention is a crystalline polypropylene, and is a homopolymer of propylene or
It contains a copolymer containing 10 mol% or less, preferably 1 to 7 mol% of an α-olefin such as ethylene, butene-1, and hexene-1.

The copolymer may be a random copolymer, a blended product with a homopolymer obtained by multistage polymerization, or an ordinary blended product. The density of polypropylene is 0.890 to 0.905 g / cm ³ , and the melt index (M
I) is 0.1 to 30 g / 10 minutes, preferably 0.2 to 20 g / 10 minutes. In addition, a modified polyolefin grafted with an unsaturated carboxylic acid such as maleic anhydride or a derivative thereof may be added to the polypropylene (A).

The ethylene / α-olefin copolymer (B) is, for example, an ethylene content of 80 to 97 mol% obtained by polymerizing ethylene and α-olefin using a polymerization catalyst composed of a vanadium compound and an organic aluminum compound, preferably Is a copolymer of 83 to 95 mol%. As the α-olefin, usually an α-olefin having 3 to 6 carbon atoms, particularly propylene and butene-1 are preferable.

The ethylene / α-olefin copolymer (B) has a density of 0.86 to 0.91 g / cm ^3, preferably 0.87 to 0.90 g / cm ³ and a low crystallinity or amorphousness with a crystallinity of 70% or less. . If the density is less than 0.86 g / cm ³ , the blocking resistance and heat resistance are poor, while if the density is more than 0.91 g / cm ³ , the vapor deposition strength is poor, which is not preferable.

In the present invention, the above-mentioned (A) polypropylene and (B) ethylene / α-olefin copolymer are used as resin components.

The compounding ratio of the above resin components is (A) polypropylene 99-
The content of the ethylene / α-olefin copolymer (B) is 1 to 40% by weight, preferably 5 to 30% by weight, based on 60% by weight, preferably 95 to 70% by weight. Here, if the compounding ratio of the polypropylene (A) exceeds 99% by weight, the vapor deposition strength will decrease, while if it is less than 60% by weight, the glitter will decrease, and thus both are not preferable.

Further, (C) organic additives include hydrocarbon lubricants such as liquid paraffin, chlorinated naphthalene, and trifluorochloroethylene low polymer as lubricants; fatty acid lubricants such as higher fatty acids, fatty acid amides, and alkylenebisfatty acid amides. ;
Fatty acid ester-based lubricants such as butyl stearate and polyglycol ester; various lubricants such as fatty acid alcohol, alcohol-based lubricants such as polyglycol. Among them, fatty acid amides such as erucic acid amide, stearic acid amide, oleic acid amide, behenic acid amide, N
-Stearyl butyric acid amide, N-stearyl caprylic acid amide, N-stearyl lauric acid amide, N-stearyl stearic acid amide, N-stearyl behenic acid amide, N-oleyl oleic acid amide, N-oleyl behenic acid amide, N- Examples thereof include butyl erucic acid amide, N-octyl erucic acid amide and N-uralyl erucic acid amide.

It is also effective to add metal soaps such as calcium stearate, zinc stearate and magnesium stearate as lubricants and free hydrochloric acid scavengers.

Further, as an antistatic agent, a cation type, an anion type,
Both nonionic and zwitterionic systems can be used. Specifically, cationic amine salts, tertiary amines, quaternary ammonium compounds, cation derivatives such as pyridine derivatives; sulfated oils, soaps, sulfated ester oils, sulfated amide oils, olefin sulfates. salts,
Anionic salts such as fatty alcohol sulfate ester salts, alkyl sulfate ester salts, fatty acid ethyl sulfonates, alkylnaphthalene sulfonates, alkylbenzene sulfonates, succinate sulfonates, and phosphate ester salts; of polyhydric alcohols Partial fatty acid ester, ethylene oxide adduct of fatty alcohol, ethylene oxide adduct of fatty acid, ethylene oxide adduct of poly-fatty amino or fatty acid amide, ethylene oxide adduct of alkylphenol, ethylene oxide adduct of alkylnaphthol, polyhydric alcohol Oxide adducts of partial fatty acid esters of nonionic compounds such as polyethylene glycol; carboxylic acid derivatives,
Examples thereof include zwitterionic compounds such as imidazoline derivatives.

Among these, nonionic ones are preferable, and polyoxyethylene alkylamine, polyoxyethylene alkylamide or their fatty acid ester, and glycerin fatty acid ester are particularly preferable.

The antioxidants can be roughly classified into phenol-based antioxidants and sulfur / phosphorus-based antioxidants. Examples of phenolic antioxidants include alkylphenols such as t-Bu-phenol and styrenated phenol; alkyldiphenols such as bisphenol; thiobisalkylphenols, and sulfur / phosphorus antioxidants include B and B. Examples include ′ -thiopropionic acid esters; phosphite esters and the like. Still other antioxidants include vitamin E.

These (C) organic additives are used in an amount of 0.3 parts by weight or less, preferably 0.2 parts by weight or less, based on 100 parts by weight of the resin component. Here, if the mixing ratio of the organic additive exceeds 0.3 parts by weight with respect to 100 parts by weight of the resin component, it is difficult to increase the vapor deposition strength, which is not preferable. When an organic lubricant is used, it is preferably used in an amount of 0.1 part by weight or less, particularly 0.06 part by weight or less, relative to 100 parts by weight of the resin component.

On the other hand, (D) inorganic additives include silicas such as natural silica and synthetic silica, zeolites such as zeolite A, zeolite X, zeolite Y, zeolite L, and mordenite, and hydrotalc stones, schititite, pyroaurite, etc. An inorganic additive selected from hydrotalcites is used.

Among these additives, zeolite and hydrotalcites are preferable, and those having an average particle diameter of 20 μm or less are preferable.

These inorganic additives (D) are used in a proportion of 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, based on 100 parts by weight of the resin component. Here, if the compounding ratio of the inorganic additive (D) is less than 0.01 parts by weight with respect to 100 parts by weight of the above resin component, the film-forming property and vapor deposition property are poor, while if it exceeds 2 parts by weight, the surface becomes rough. It is not preferable.

The polypropylene film for metal vapor deposition of the present invention is obtained by forming a composition comprising the above components (A), (B), (C) and (D) and then subjecting it to corona discharge treatment.
The film formation method may be any of the usual T-die method or inflation method, or the uniaxial or biaxial stretching method. As film forming conditions, a method of melt-kneading at 200 to 300 ° C. and then cooling using a roll at 70 ° C. or lower can be adopted.

The condition of the corona discharge treatment performed after film formation is not particularly limited, but usually the power consumption is 30 to 200 W / m ² / min, preferably 35 to 150 W / m ² / min, and the treatment atmosphere is air,
It is nitrogen (oxygen concentration of 5% or less) or carbon dioxide gas. The processing speed may be 10 to 200 m / min.

The polypropylene-based film for metal vapor deposition of the present invention is as described above, but a metal vapor-deposited polypropylene-based film may be obtained by vapor-depositing a metal on the surface of a film thus treated by corona discharge, or other You may laminate | stack and use a base material film.

The method of metal deposition on the surface of polypropylene film is to make the film high vacuum (10 ^-4 to 10 ^-5 Torr, usually 5 × 10 ^-5 Torr).
It may be kept inside and vaporized metal vapor may be introduced into the inside to vapor-deposit it on the surface of the polypropylene film. Alternatively, a sputtering method in which a metal is blown off for vapor deposition using glow discharge or an ion plating method in which a substrate is etched and vaporized by argon ionized and accelerated by electric discharge may be used.

The metal to be deposited may be aluminum, titanium, chromium, nickel, copper, silver, gold, zinc, germanium, tin, selenium, etc., but aluminum is preferable in terms of workability, reflectance, economy and the like. In this case, the thickness of the aluminum vapor deposition layer is usually 400 to 600Å.

〔Example〕

 Next, the present invention will be described in detail with reference to Examples.

Examples 1 to 4 and Comparative Examples 1 to 3 Compositions having the formulations shown in Table 1 were extruded from a T-die with a die width of 800 mm at a die temperature of 250 ° C. by a 65 mmφ extruder, and then cooled by a chill roll (40 ° C.). One side was subjected to corona discharge treatment (in air atmosphere) at 41 W / m ² / min to obtain a film having a thickness of 25 μm.

Table 1 shows the evaluation results of the wetting index of the corona discharge treated surface of these films, the vapor deposition strength when aluminum is vacuum deposited, and the glitter.

Comparative Example 4 Example 1 except that the corona discharge treatment was not performed.
4 and Comparative Examples 1 to 3, films were obtained and evaluated. The results are shown in Table 1.

Reference Example A film was obtained and evaluated in the same manner as in Examples 1 to 4 and Comparative Examples 1 to 3 except that the corona discharge treatment was performed under the condition of 35 W / m ² / min. The results are shown in Table 1.

[Advantages of the Invention] As described above, according to the present invention, a metal vapor deposition film having high metal vapor deposition strength as compared with a conventional polypropylene-based film, having little change over time in its strength, and having excellent glitter is obtained. To be Further, it is possible to obtain a polypropylene-based film for metal vapor deposition, which has good laminate adhesion with other base film or improved printability and has extremely excellent physical properties as a packaging material, particularly as a laminate base material.

Claims (2)

[Claims] 1. To 100 parts by weight of a resin component comprising (A) 99 to 60% by weight of polypropylene and (B) 1 to 40% by weight of an ethylene / α-olefin copolymer having a density of 0.86 to 0.91 g / cm ³ , (C) 0.3 parts by weight or less of organic additive and (D)
A polypropylene film for metal vapor deposition, which is obtained by forming a composition containing 0.01 to 2 parts by weight of an inorganic additive selected from silicas, zeolites, and hydrotalcites and then subjecting it to corona discharge treatment. 2. The polypropylene film for metal vapor deposition according to claim 1, which has a wetting index of 40 dyne / cm or more.