JPH0618948B2 - Polyolefin resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyolefin resin composition. More specifically, it has excellent heat-sealing properties, adhesion of vapor-deposited films, and suitability for printing and laminating on vapor-deposited surfaces, and can be used for film winding during film forming and vapor deposition processing, such as "wrinkles" and "rolls". Prevents defects and impact resistance
The present invention relates to a polyolefin-based resin composition for metal-deposited film having improved tear strength.

[Conventional technology]

In recent years, a metal-deposited film obtained by vapor-depositing a metal on a plastic film under vacuum has been widely used for food packaging by utilizing its excellent decorative properties, gas barrier properties, light blocking properties, etc. Also used for building materials,
Applications are expanding.

In particular, aluminum vapor-deposited films are used in large amounts mainly for food packaging applications because of their versatility and beautiful metallic luster, but conventionally commercially available crystalline polypropylene, polypropylene such as crystalline propylene / α-olefin copolymer, etc. The vapor deposition of metal such as aluminum on the system film has extremely weak adhesion of the vapor deposition film, and the printability and adhesiveness of the vapor deposition surface are extremely low, so it can hardly be used for packaging that requires printing, laminating, etc. It was a situation, and it was a big obstacle to the application development.

As a result of detailed investigations on this cause, the present inventors found that
As described in the specification of JP-A-59-25829, it has been found that the higher fatty acid derivative added to the polypropylene film has the most adverse effect.
However, higher fatty acid salts such as calcium stearate are commonly used as hydrochloric acid catching agents, and higher fatty acid amides such as oleic acid amide / erucic acid amide and stearic acid amide are commonly used as slip agents and essential additives for polypropylene films. However, polypropylene containing no such additives causes many problems during film formation or in post-processing of the film. In particular, when the above-mentioned slip agent is not added, as described in the same publication, the slipperiness and blocking resistance of the film are extremely lowered and wrinkles are formed on the film, and a hump is formed, resulting in a significant decrease in productivity. Let
Especially, the crystal melting point is 150 ° C, which has low rigidity and high tackiness.
In the case of the following crystalline propylene / α-olefin copolymer, this tendency is more remarkable, and as the film becomes wider / thinner and the winding becomes longer, the printability / adhesiveness of the vapor deposition surface It was a major obstacle to the production of excellent metallized polypropylene film.

[Problems to be Solved by the Invention]

The present inventors have studied to obtain a film suitable for metal vapor deposition without losing the properties of the crystalline propylene / α-olefin copolymer excellent in impact resistance / low temperature heat sealability, and have investigated specific polyethylene. Japanese Patent Application Laid-Open No. 59-25829 was proposed using a composition in which a specific amount of This publication describes crystalline propylene / α having a crystalline melting point of 150 ° C. or less.
4 to 2 high density polyethylene having an MI to MFR ratio of 0.7 or more relative to the olefin copolymer
The main idea is to use a composition added with 0% by weight. However, since the composition needs to add a large amount of 4 to 20% by weight of high density polyethylene having a relatively high MFR, the obtained film is Although the adhesiveness of the vapor-deposited surface of the metal vapor-deposited film, printing / laminating suitability and slip property and blocking resistance are improved, the orientation in the take-up direction advances during film formation and the tear strength parallel to the take-up direction is extremely reduced. There was a big drawback.

The object of the present invention is impact resistance, without losing the properties of the crystalline propylene / α-olefin copolymer excellent in low temperature heat sealability, excellent in adhesiveness of a vapor deposition film and printing / laminating suitability on a vapor deposition surface, In addition, it is excellent in slip resistance and blocking resistance, prevents film winding defects such as "wrinkles" and "rolled bumps" during film winding during film forming and vapor deposition processing, and has improved tear strength metal deposition. It is intended to provide a polyolefin resin composition for a film.

[Means for Solving the Problems]

The present inventor conducted various studies to obtain a metal vapor deposition film having excellent tear strength without losing the features of the vapor deposition film using the composition system comprising the above specific copolymer and polyethylene, and the MI A specific polyethylene having an MFR ratio with the copolymer above a certain level and a polyethylene having an MI lower than that of the specific polyethylene and having a MFR ratio with the copolymer below a certain level are added together in specific amounts. The inventors have found that an excellent metal vapor deposition film of interest can be obtained by using the composition described above, and have reached the present invention.

That is, the present invention has a propylene component content of 70% by weight or more, a crystal melting point of 150 ° C. or less, and a melt flow rate (MFR).
Is a polyolefin-based resin for metal-deposited film, which is obtained by blending 100 parts by weight of crystalline propylene / α-olefin copolymer A in the range of 2 to 20 with polyethylene-based resins B and C described in (1) and (2) below. Composition (1): Density 0.93 or more, melt index (M
I) is 10 or less, and the ratio MI / MFR with the melt flow rate (MFR) of the above copolymer A is less than 0.7: polyethylene resin B: 0.1 to 3 parts by weight, (2): Density 0.94 or more, melt index (M
1 to 7 parts by weight of high-density polyethylene C having a ratio MI / MFR of 1.0 or more and I) of 2.0 or more and a melt flow rate (MFR) of the copolymer A.

It is about.

The configuration will be described in more detail below.

The crystalline propylene / α-olefin copolymer used in the present invention is a binary or more copolymer of propylene containing 70% by weight or more of a propylene component and ethylene or an α-olefin having 4 or more carbon atoms, Crystal melting point (hereinafter T
abbreviated as m) is 150 ° C. or less. If the propylene component does not reach 70% by weight, the blocking resistance of the obtained film is remarkably lowered, and the workability and the winding form are significantly deteriorated.

If the Tm exceeds 150 ° C, the low-temperature heat-sealing property and the high-speed heat-sealing property are remarkably deteriorated, which is not practically preferable.

The Tm referred to here is the peak temperature 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. As expected. In the case of the copolymer, Tm decreases as the content of the monomer component to be copolymerized increases. For example, in the case of an ethylene / propylene random copolymer, the ethylene copolymerization ratio varies slightly depending on the randomness of the copolymer. If it exceeds about 2.5% by weight, it will be 150 degrees or less. In addition,
T of a block copolymer obtained by multistage polymerization of two or more stages such as an ethylene / propylene block copolymer
m is generally 150 ° C. or higher (in addition, 128 as a sub-peak
A small peak appears at around 0 ° C.), the film has extremely poor heat sealability, and the gloss of the vapor deposition surface is extremely low, so that the film cannot be used in the present invention.

The above-mentioned copolymer used in the present invention is obtained by randomly copolymerizing ethylene as a main component with propylene as a main component or α-olefin having 4 or more carbon atoms by a known method using a Ziegler-Natta catalyst or the like. You can get it.

Specific examples of such a copolymer include an ethylene / propylene copolymer, a propylene / butene-1 copolymer, an ethylene / propylene / butene-1 copolymer, an ethylene / propylene copolymer.
Examples include propylene / hexene-1 copolymer.

Further, the copolymer has a melt flow rate (MFR) of 2 to 20, particularly preferably 4 to 17, and when the MFR is less than 2, the smoothness of the film surface is poor and the metallic gloss of the deposited film is Lost, slip property when exceeding 20
The blocking resistance is significantly deteriorated, the tear strength is lowered, and the film becomes brittle, which is not preferable.

The polyethylene resin used in the present invention is a homopolymer of ethylene and a copolymer of ethylene as a main component (preferably containing 90% by weight or more) and an α-olefin having 3 or more carbon atoms, such as carboxylic acid. The modified polyethylene grafted with is also included. The present invention has a density of 0.93 or more and 0.94 or more among these polyethylene resins,
At the same time, two kinds of polyethylene having different MFR are used in combination and added to the above copolymer.

That is, one polyethylene resin B has a density of 0.93.
As described above, the melt index (MI) must be 10 or less, and the ratio MI / MFR of the above copolymer must be MI / MFR <0.7. When the density of B is less than 0.93, the slip property is insufficient, and when MI exceeds 10, or when MI / MFR is 0.7 or more, the blocking resistance is insufficient, so a large amount needs to be added. However, the tear strength of the film is lowered and the film becomes brittle, which is not preferable.

The other polyethylene resin C has a density of 0.9.
4 or more, MI is 2.0 or more, preferably 3 or more, and
The ratio MI / MFR of the above copolymer is MI / MFR ≧ 1.0. If the density of C is less than 0.94, both the slip property and the blocking resistance are insufficient, and if MI is less than 2.0 or MI / MFR is less than 1.0, the smoothness of the film is significantly reduced and the vapor deposition surface Luster and brightness are lost, which is not desirable.

The present invention comprises the above-mentioned copolymer A and the above-mentioned two kinds of polyethylene resins B and C, and the compounding ratio thereof is B: 0.1-3 parts by weight and C: 1-7 with respect to 100 parts by weight of A. It must be in the range of parts by weight. Even if either B or C is insufficient, either slip resistance or blocking resistance is insufficient, the surface roughness of the film becomes excessive when B exceeds 3 parts by weight, and fisheye-like irregularities occur on the film. Or
It is not preferable because the brightness and gloss of the vapor-deposited film are significantly reduced and the metallic feeling is lost. On the other hand, if C exceeds 7% by weight, the tear strength of the film decreases, which is not preferable.

Therefore, B with MI / MFR of 0.65 or less is 0.3
2 to 4 parts by weight and 2 to 4 parts of C having MI / MFR of 1.3 or more
It is particularly desirable to blend the compounding agent in the range of parts by weight because the workability and the various characteristics of the vapor-deposited film are well balanced. In addition, said B and C are 2 or more types within the limited addition amount range, for example, 2 or more types of B with different MI or density are combined, and 2 or more types of C with different MI or density are combined likewise. The composition to be added is also included.

In the composition composed of the crystalline propylene / α-olefin copolymer and two kinds of polyethylene resins used in the present invention, an antioxidant, an inorganic filler, other kinds of polymers and the like are added as necessary. However, in order to maintain the excellent adhesive strength of the vapor-deposited film and the printability / lamination suitability of the vapor-deposited surface, which is the object of the present invention, calcium stearate, zinc stearate, etc. which are conventionally used for polyolefin films can be used. It is desirable not to add fatty acid derivatives such as higher fatty acid salts and fatty acid amides such as erucic acid amide and stearic acid amide as described above. Desirable additives that can be added include the antioxidants having a molecular weight of 500 or more described in JP-A-59-25829, silica having an average particle size of 5 microns or less, inorganic materials such as zeolites and hydrotalcites. Examples of the filler and other polymers such as maleic anhydride-grafted polypropylene and ethylene / α-olefin copolymer rubber are preferable, and it is particularly desirable to suppress the blending amount of these polymers to the minimum.

As a mixing method for obtaining the composition used in the present invention, any of the conventionally known Henschel mixer, Banbury mixer, various kneaders, extruders and the like can be used. Further, pellets obtained by separately pelletizing the above copolymer and two kinds of polyethylene resins may be mixed and used at the time of film formation.

As a method for forming a film using the composition of the present invention, a known T-die method, a tubular method or the like can be used, but a melt-extruded composition is 70 ° C. or less, preferably 50.
It is desirable that the fissures should be formed under the condition that they are rapidly cooled below ℃. If the film is cooled at a temperature higher than 70 ° C., the film tends to be extremely brittle and the low temperature heat sealability tends to deteriorate. Further, the obtained film or the like is preferably subjected to surface treatment by a known method such as corona discharge treatment, fire treatment, plasma treatment for improving adhesion, and then metal vapor deposition is performed on the treated surface under vacuum to obtain an object. The metal vapor-deposited polyolefin film can be obtained.

This surface treatment may be carried out at an appropriate time after the film is formed and before the metal is vapor-deposited, but it is most convenient to carry out the film treatment between the film formation and the winding in view of film productivity. The degree of this surface treatment is
The wetting index measured by the method of JIS K-6758 is 37.
It is desirable to treat it so that it is more than dyn / cm. 3
9 dyn / cm or more is particularly desirable. Further, in order to strengthen the adhesion between the film and the metal, an adhesive such as polyester, polyurethane, or epoxy resin may be thinly anchor-coated on the treated surface of the film and then evaporated.

The method of depositing a metal on a film sounding from the composition of the present invention is a vacuum vapor deposition method, that is, a feeding part of the film, a vapor deposition part,
In a vacuum vapor deposition device equipped with a winding unit, etc.,
The filament to which a target metal such as aluminum, nickel, gold, and silver is attached is heated under reduced pressure of about 0 ⁻⁴ to 10 ⁻⁵ Torr to dissolve and evaporate the metal, and to evaporate molecules on the film surface. A method of continuously vapor-depositing and winding is common, but it is also possible to use other methods such as sputtering vapor deposition and ion plating method utilizing development in which the metal constituting the cathode scatters when discharged in a vacuum. .

The metals to be vapor-deposited include aluminum, gold, silver,
Copper, nickel, chromium, germanium, titanium, selenium, tin, zinc and the like can be mentioned, but aluminum is particularly desirable in view of workability, economy, productivity, etc., and the composition of the present invention is particularly effective for this aluminum. Therefore, it is most effective not only for improving the workability and productivity of vapor deposition, but also for improving the adhesiveness of the vapor deposition film, the brightness, the printing of the vapor deposition film, the suitability for lamination, and the like, which is the object of the present invention.

The thickness of the metal vapor deposition layer can be arbitrarily changed according to the purpose, but in the case of a film, it is usually desirable to have a thickness of about several tens to several hundreds of angstroms (Å) in terms of adhesion and durability.

In addition, a method in which the composition of the present invention is used as a laminated film of two or more layers as one layer, and metal is vapor-deposited on either the layer made of the composition of the present invention or the other layer made of another composition is also very effective. It is effective, and is also particularly useful when metal vapor deposition is performed on the other surface layer of a coextruded laminated film of two or more layers made of a crystalline polypropylene resin having a crystal melting point of 155 ° C. or higher.

(Measurement Method of Characteristics and Evaluation Criteria) The measurement and evaluation of characteristics in the present invention were performed by the following methods and criteria.

(1) Density: Measured at 23 ° C. according to JIS K7112. (Unit: g / cm ³ ) (2) Melt flow rate (MFR): JIS K721
The flow characteristics (unit: g / 10 minutes) of the crystalline propylene-based copolymer and the crystalline propylene-α-olefin copolymer measured under test condition 14 of 0-1976 (230 ° C, 2.16 kg load) are shown. .

(3) Melt index (MI): JIS K7210
-1976 test condition 4 (190 ° C, 2.16 kg load)
Flow characteristics of polyethylene resin measured with (simple: g /
10 minutes).

(4) Crystal melting point (Tm): Scanning differential calorimeter (abbreviation: DS)
It is represented by the peak temperature (unit: ° C) of the endothermic curve accompanying the melting of the crystal obtained by heating 10 mg of the sample under a nitrogen atmosphere at a rate of 10 ° C / minute using C).

(5) Wetting index: The surface treatment surface of the film and the metal vapor deposition surface were measured by the method of JIS K-6768. (Unit: d
yn / cm) (6) Blocking degree: 2 pieces of sample with width 2 cm and length 10 cm are overlapped with each other by surface treatment surface in case of original film and non-evaporation surface in case of vapor deposition film by 2 cm in length. Together,
With a bottom of 2 cm x 2 cm and a weight of 1 kg placed on the overlapped part, leave it for 24 hours in an atmosphere with a temperature of 40 ° C and a humidity of 90% RH, and then apply the force required for shearing and peeling of the overlapped part. Tensile tester (determined at a pulling speed of 300 mm / min. (Unit: g / 4 cm ² ) (7) Film winding form: A film roll obtained by continuously winding a fixed length of raw film or vapor deposition film Were visually observed, and those having a flat surface and no wrinkles (wrinkles) or thickening (rolled lumps) were evaluated as ○ (good winding appearance), and those having wrinkles or thickening were evaluated as × (poor winding appearance).

(8) Tear strength: Based on ASTM D1922 Elmendorf tear strength (unit: g / mil).

(9) Flip property: Shown as a coefficient of sliding (movement) friction measured by the method defined in ASTM D1894-63.

(10) Adhesiveness of vapor-deposited film: A 90-degree peeling strength (unit: unit) required for peeling the biaxially stretched polyester film (PET) film after the film is attached to the vapor-deposited film via a urethane adhesive. g / 15 mm). Peeling occurs between the film surface and the vapor deposition surface, and the larger this value, the better the adhesiveness.

[Examples and comparative examples]

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Examples 1 to 9 and Comparative Examples 1 to 6) Tetrakis [methylene-3- (2 '
0.15% by weight of 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane and 0.1 of hydrotalcite powder having an average particle size of 1.2μ as an inorganic filler.
94% by weight of a propylene component containing 0% by weight, 3.5% by weight of an ethylene component, 2.5% by weight of a butene-1 component, MFR 6.8, crystalline ethylene / propylene / butene-1 ternary having a Tm of 140 ° C. 16 parts of pelletized composition obtained by mixing 100 parts by weight of the copolymer and a mixture of the polyethylene resin shown in Table 1 with a Henschel mixer and then melt-kneading at 200 ° C. using an extruder. Extruder with a diameter of 75 mm and 120 mm
A film having a width of T is used to form a film at a resin temperature of 220 ° C. and a cooling roll temperature of 25 ° C. Immediately, one side of the film is subjected to corona discharge treatment and wound up to obtain a wetting index of 41 d on the treated surface.
A roll-shaped original film having a thickness of 22 μm and a width of 80 cm was obtained. This raw film was cut into a width of 60 cm using a slitter, and then set in a continuous vacuum vapor deposition apparatus, and while continuously rolling the film, aluminum vapor deposition was performed on the corona discharge treated surface under a vacuum of 10 ⁻⁴ Torr or less. Then, the film was wound up to obtain a roll-shaped vapor deposition film having a vapor deposition film thickness of 0.04 μm. The characteristics of the raw film and the vapor-deposited film are shown in Table-2.

As is clear from Table-1 and Table-2, from the composition in which two kinds of polyethylene resins, polyester resins B and C, in the limited range used in the present invention are added in combination, various properties are extremely excellent. Although a raw film and a vapor-deposited film can be obtained, any of the properties is inferior in the comparative example using a composition outside this range, which is not preferable.

[Effects of the Invention] The metal-deposited film using the composition of the present invention has excellent slip properties and blocking resistance as compared with conventionally known crystalline polypropylene-based metal-deposited films, and also has tear strength and adhesiveness on the vapor-deposited surface. Good, it can be put to practical use without adding a fatty acid derivative, so it has good printing and laminating suitability on the vapor deposition surface. Therefore, it is effective in improving productivity and workability such as speeding up and improving yield in secondary processing steps such as printing, laminating and automatic bag making. The vapor deposition film obtained has an excellent metallic luster,
The decorative property, light blocking property and gas barrier property can be utilized more effectively, and it can be used in a wide range of applications such as packaging of various foods and textile products, various containers for building materials, and the like.

Claims (1)

[Claims] 1. A crystalline propylene having a propylene component content of 70% by weight or more, a crystalline melting point of 150 ° C. or less, and a melt flow rate (MFR) of 2 to 20.
With respect to α-olefin copolymer A: 100 parts by weight, the following
A polyolefin resin composition for metal-deposited film, comprising the polyethylene resins B and C of (1) and (2). (1): Density 0.93 or more, melt index (M
I) is 10 or less, and the ratio MI / MFR with the melt flow rate (MFR) of the copolymer A is less than 0.7: polyethylene resin B: 0.1 to 3 parts by weight, (2): Density 0.94 or more, melt index (M
1 to 7 parts by weight of high-density polyethylene C having a ratio MI / MFR of 1.0 or more and I) of 2.0 or more and a melt flow rate (MFR) of the copolymer A.