CN1052943C - Coextruded metallizable cast film for high Al adhesion - Google Patents

Abstract

The present invention discloses a coextruded, Al metal cast polypropylene film which has improved aluminum to film adhesion properties. The Al surface layer on the vacuum is composed of thermoplastic isotactic homopolypropylene or copolymer, and blended with a polar polymer material with good miscibility.

Description

Coextruded gold cast film with high adhesion to aluminum

This invention relates to coextruded, thermoplastic cast films, and more particularly to aluminum-coated cast polypropylene films which have improved adhesion between the aluminum and the film.

Generally, metal-cast polypropylene films on Al are widely used in food packaging, such as fast food and noodles, due to their high gloss, excellent moisture/oxygen barrier, and low heat-sealing properties.

These upper metal cast films are extrusion laminated polyethylene (MI7.5, softening temperature 84°C) and printed materials at a temperature of 300-320°C. This high extrusion temperature of polyethylene causes the shrinkage of the cast propylene film and damages the adhesion between the aluminum and the film. The destruction of the aluminum adhesion will cause a sharp drop in gloss, moisture and oxygen barrier properties, Ultimately the polyethylene comes off the printed material of the food packaging.

If the extrusion temperature of polyethylene is reduced to reduce the damage to the adhesion between aluminum and the film, the bonding strength between polyethylene and Al on the gold film will be weakened due to insufficient oxidation of polyethylene.

Accordingly, an object of the present invention is to provide an aluminum-coated cast film having excellent adhesion. That is, the purpose of the present invention is to provide an Al co-extruded cast film that can still maintain excellent gloss, water vapor and oxygen permeability after extrusion lamination.

The co-extruded cast film with high adhesion to Al provided by the present invention comprises:

a) a central layer comprising thermoplastic isotactic polypropylene;

b) a surface layer of said central layer comprising a heat-sealable polypropylene copolymer;

c) Another surface layer of the central layer, which as an Al metal layer on vacuum contains thermoplastic isotactic homopolypropylene or polypropylene copolymer and a polar material with good miscibility with polypropylene, the polar material is selected from ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ionomer, polyester elastomer, polymethyl methacrylate copolymer, malay Anhydride or acetate grafted polymers or blends thereof.

This type of film exhibits excellent properties, including excellent adhesion between Al and the film substrate, gloss, and excellent water vapor and gas permeability, even in polyethylene and oriented polypropylene or polyester extruded layers. These properties can also be better maintained after pressing.

For a better understanding of the present invention, among other purposes, the detailed description follows and the scope thereof is pointed out in the appended claims.

The method for producing the cast polypropylene film of the present invention will be described in detail below.

The cast polypropylene film consists of a three-layer structure, including a central layer (A), a heat-sealing surface layer (B) composed of polypropylene copolymer, and a gold surface layer (C), which contains homopolypropylene, polypropylene copolymer Compounds or their blends and polar polymer materials with good miscibility with polypropylene. The material of the center layer is homopolypropylene, especially isotactic homopolypropylene containing only antioxidant and Cl capture agent. Other additives such as anti-blocking agents, slip agents, or antistatic agents can migrate to the upper gold surface layer, thereby weakening the bond strength of the aluminum to the film.

The above-mentioned antioxidant can be 2,6-di-tert-butyl-4-methylphenol, 3,5-di-tert-butyl-4-hydroxyhydrocinnamate octadecyl ester, thiodipropyl dilauryl thiolate, di(mirystyl)thiodipropionate, and tris(2,4-di-tert-butylphenyl)phosphite. The Cl capture agent can be calcium stearate, zinc stearate, DHT-4A (hydrated magnesium aluminum hydroxycarbonate). These antioxidants and Cl-scavenging agents are not particularly limited, but those commonly used for polypropylene can be used.

The heat-sealable surface layer of one of the two surface layers is a polypropylene copolymer, such as a propylene-ethylene copolymer, a propylene-butene copolymer, a propylene-octene copolymer, a propylene-ethylene-butene terpolymer, or Propylene-ethylene-octene terpolymer. The anti-adhesive agent used in this surface layer can prevent film-to-film adhesion, and the thickness of the surface layer is in the range of 1/70 to 1/2 of the total thickness of the film, and 1/25-1/2 is particularly desirable.

The other surface layer, the Al metal layer on the vacuum, is isotactic homopolypropylene, or a blend of polypropylene copolymer and a polar polymer material with good miscibility with polypropylene that can also be used for the sealable layer thing. Polar polymer materials are ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ionomers, polyester elastomers, polymethyl methacrylate, Maleic anhydride or acetate grafted polymers or blends thereof. These materials increase the bonding strength between Al and the upper gold layer without destroying other physical properties.

The content of these polar polymers ranges from 1 to 50% by weight of the isotactic polypropylene or polypropylene copolymers useful in the heat seal layer or blends thereof. If the content exceeds 50% (by weight), the glossiness of the upper gold film will decrease. If the content is less than 1% by weight, the adhesion of Al to the film will be deteriorated.

In addition to the above-mentioned polar materials, polyterpenes, polybutenes, acyclic hydrocarbon polymers or their blends can also be optionally used, which is not to increase the bonding strength of Al, but to increase film gloss. The thickness of the upper gold layer is 1/100-1/2 of the total film thickness.

The ideal film thickness of the gold-coated cast polypropylene film of the present invention is 10 μm-100 μm. If the film thickness exceeds this range, it is uneconomical economically. The preferred thickness of the upper Al metal layer is 25-500 Å, however, 100-300 Å is satisfactory. If the thickness is less than 25 Å, the gloss and barrier properties will be destroyed. If the thickness exceeds 500 Å, even if there is a large amount of Al deposition, the influence on the glossiness and the performance of the anti-seepage layer becomes gentle, and because of the additional cost of Al, it is not economical.

Unlike the usual cast polypropylene film on Al, Al high adhesion and co-extruded cast polypropylene film and its gold film maintain excellent performance, such as excellent strong moisture resistance and oxygen permeability, high Gloss, and no matter how high the extrusion lamination temperature is, the lamination productivity can be increased by 10%.

The following examples illustrate the essence of the invention. Example 1

Composition (A)(1) contains 1,000 ppm tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) methane and 300 ppm calcium stearate Isotactic homopolypropylene manufactured by Honam Petrochemical Company, Korea "FC 150B" (trade name) [Tm (melting point) 165°C, MI (melting contact index) 4.0, isotacticity 96%]: 10kg (100% by weight ).

Composition (B) (1) Polypropylene terpolymer (ethylene-butene-propylene; 4%, 4%, 92%) manufactured by Honam Petrochemical Co., Korea "SFC 750B" (trade name) [Tm 125°C, MI4,): 2kg (100% weight)

Composition (C) (1) Terpolymer as in (B) layer: 1.9 kg (95% by weight) (2) Ethylene vinyl acetate (content of vinyl acetate 5%), manufactured by Hangyang Petrochemical Co., Korea "EVA 1123" (trade name): 100 g (5% by weight).

The above-listed compositions (A), (B) and (C) were respectively melt-kneaded in respective extruders and sent to the co-extrusion film head (mouth). The extruder barrel temperatures were 180, 190, 200 and 250°C for the (A) layer and 200, 250 and 250°C for the (B) and (C) layers, respectively. The molten composition is coextruded in a die in such a way that composition (A) is located in the middle layer and compositions (B) and (C) are located on the two outer sides of the middle layer.

Then cast the co-extruded structure on a casting roll, and wind the Al base film on it at a speed of 130 m/min.

Then, in a vacuum chamber with a pressure of 0.013 Pascal (10 ⁻⁴ Torr), Al metal was applied to the obtained cast film at a rate of 600 m/min, and the thickness of the Al metal was controlled at 200 Å.

Gained result is listed in table 1 embodiment 2 and embodiment 3

A coextruded cast polypropylene film having high adhesion to Al was prepared in substantially the same manner as in Example 1 except that the composition (C) was replaced by the following composition (C'), respectively. Example 2

Composition (C') (1) Terpolymer "SFC 750B": 1.8kg (90% by weight) (2) Ethylene vinyl acetate copolymer (content of vinyl acetate 5%) "EVA1123": 200g (10% weight) embodiment 3

Composition (C') (1) Terpolymer "SFC 750B": 1.7kg (85% by weight) (2) Ethylene vinyl acetate copolymer (content of vinyl acetate 5%) "EVA 1123": 300g (15 % by weight) embodiment 4-embodiment 6

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 4

Composition (C') (1) Terpolymer "SFC 750B": 1.9 kg (95% by weight) (2) Polyester elastomer manufactured by Kolon, Korea "KP 3772" (trade name) [MI7, Tm 216°C 〕: 100g (5% by weight) embodiment 5

Composition (C') (1) Polymer "SFC 750B": 1.8kg (90% by weight) (2) Polyester elastomer "KP 3772": 200g (10% by weight) Example 6

Composition (C') (1) Terpolymer "SFC 750B": 1.7kg (85% by weight) (2) Polyester elastomer "KP 3772": 300g (15% by weight) Example 7 - Example 9

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 7

Composition (C') (1) Terpolymer "SFC 750B", 1.9 kg (95% by weight) (2) Maleic anhydride graft polymer manufactured by Honam Petrochemical Co., Korea "FP 150SL" (trade name) [MI10, Tm165°C]: 100g (5% by weight) Example 8

Composition (C') (1) Terpolymer "SFC 750B": 1.8kg (90% by weight) (2) Maleic anhydride grafted polymer "FP 150SL": 200g (10% by weight) Example 9

Composition (C') (1) Terpolymer "SFC 750B": 1.7kg (85% by weight) (2) Maleic anhydride grafted polymer "FP 150SL": 300g (15% by weight) Example 10—Implementation Example 12

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 10

Composition (C') (1) Terpolymer "SFC 750B": 1.9 kg (95% by weight) (2) Ethylene vinyl acetate (vinyl acetate 5%) "EVA 1123": 50 g (2.5% by weight) ( 3) Polyester elastomer "KP 3772": 50g (2.5% by weight) Example 11

Composition (C') (1) Terpolymer "SFC 750B": 1.8kg (90% by weight) (2) Ethylene vinyl acetate (vinyl acetate 5%) "EVA1123": 100g (5% by weight) (3 ) polyester elastomer "KP 3772": 100 g (5% by weight) Example 12

Composition (C') (1) Terpolymer "SFC 750B": 1.7 kg (85% by weight) (2) Ethylene vinyl acetate (vinyl acetate 5%) "EVA 1123": 150 g (7.5% by weight) ( 3) Polyester elastomer "KP 3772": 150g (7.5% by weight) Example 13-Example 15

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 13

Composition (C') (1) Terpolymer "SFC 750B": 1.9 kg (95% by weight) (2) Ethylene vinyl acetate copolymer (vinyl acetate 5%) "EVA 1123": 50 g (2.5% by weight ) (3) maleic anhydride graft polymer "FP 150SL": 50g (2.5% by weight) embodiment 14

Composition (C') (1) Terpolymer "SFC 750B": 1.8 kg (90% by weight) (2) Ethylene vinyl acetate copolymer (vinyl acetate 5%) "EVA 1123": 100 g (5% by weight ) (3) maleic anhydride graft polymer "FP 150SL": 100g (5% by weight) embodiment 15

Composition (C') (1) Terpolymer "SFC 750B": 1.7 kg (85% by weight) (2) Ethylene vinyl acetate copolymer (vinyl acetate 5%) "EVA 1123": 150 g (7.5% by weight (3) maleic anhydride grafted polymer "FP 150SL": 150g (7.5% by weight) embodiment 16-embodiment 18

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 16

Composition (C') (1) Terpolymer "SFC 750B": 1.9 kg (95% by weight) (2) Polyester elastomer "KP 3772": 50 g (2.5% by weight) (3) Maleic anhydride grafted Polymer "FP 150SL": 50 g (2.5% by weight) Example 17

Composition (C') (1) Terpolymer "SFC 750B": 1.8 kg (90% by weight) (2) Polyester elastomer "KP 3772": 100 g (5% by weight) (3) Maleic anhydride grafted Polymer "FP 150SL": 100 g (5% by weight) Example 18

Composition (C') (1) Terpolymer "SFC 750B": 1.7kg (85% by weight) (2) Polyester elastomer "KP 3772": 150g (7.5% by weight) (3) Maleic anhydride graft Polymer "FP 150SL": 150 g (7.5% by weight) Example 19

Except using the following composition (C') instead of composition (C) to improve the metallic luster of the upper gold film, the same method as in Example 1 is basically used to prepare a co-extrusion casting with high adhesion to Al Polypropylene film.

Composition (C') (1) Terpolymer "SFC 750B": 1.6 kg (80% by weight) (2) Polyester elastomer "KP 3772": 150 g (7.5% by weight) (3) Maleic anhydride grafted Polymer "FL 150SL": 150g (7.5% by weight) (4) Polybutene manufactured by Shell Chemical Company U.S.A, (MI250, Tm125°C) "DP 0800": 100g (5% by weight) Example 20—Example twenty two

A coextruded cast polypropylene film having high adhesion to Al was prepared substantially in the same manner as in Example 1, except that the composition (C) was replaced with the following composition (C'), respectively. Example 20

Composition (C') (1) Terpolymer "SFC 750B": 1.7 kg (85% by weight) (2) Ethylene ethyl acrylate copolymer (E.A.9%) "Evaflex-EEA A -701" (trade name): 100g (5% by weight) (3) polyterpene manufactured by Eastman Chemical Company, "Eastotac H-130W hydrocarbon resin" (trade name): 100g (5% by weight) (4) by Polymethylmethacrylate manufactured by Hangyang Petrochemical Company Korea, "HY 040H" (trade name): 100 g (5% by weight) Example 21

Composition (C') (1) Terpolymer "SFC 750B": 1.7 kg (85% by weight) (2) Acetate grafted polymer (1% of acetic acid grafted to polypropylene) manufactured by STC Corporation, Korea : 200g (10% by weight) (3) ethylene methyl acrylate copolymer manufactured by EXXON Chemical Company, "TC120A" (trade name): 100g (5% by weight) Example 22

Composition (C') (1) Terpolymer "SFC 750B": 1.7 kg (85% by weight) (2) Ethylene acrylic acid copolymer (acrylic acid 7%) manufactured by Mitsubish Petrochemical Company, "Yukalon A201M" (trade name ): 200 g (10% by weight) (3) Ionomer manufactured by EXXON Chemical Co., "ESCOREX 900" (trade name): 100 g (5% by weight)

The following commercially available control experiments were carried out under the same conditions as the above-mentioned examples which clearly show the advantages of the present invention. Comparative Example 1

Except that composition (C) is identical to composition (B), cast polypropylene film is prepared by the same method as in Example 1

Table 1 has listed the experimental results of Example 1-Example 19 and Comparative Example 1 Al bond strength and gloss after polyethylene extrusion lamination, and Table 2 has listed Comparative Example 1 and Example 1 Experimental results of Al adhesion strength, gloss, oxygen transfer rate and water vapor transfer rate.

While the foregoing descriptions have given an understanding of the preferred embodiments of the invention, those skilled in the art will recognize that changes and modifications can be made without departing from the spirit of the invention, and it is contemplated that all such changes All modifications and improvements are intended to fall within the true scope of the invention.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Adhesive strength to Al (g/15mm) 60 80 94 120 1 29 150 96 99 120 69 98 61 Adhesion strength to Al (% growth) 200 267 280 400 430 500 320 330 400 230 326 203 Gloss ◎ ◎ ○ ◎ ○ ◎ ◎ ◎ ◎ ◎ ◎ ○ Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Comparative Example 1 Adhesive strength to Al (g/15mm) 59 84 87 250 256 264 264 120 150 180 30 Adhesion strength to Al (% growth) 197 285 290 830 853 880 880 400 500 600 100 Gloss ◎ ○ ○ ◎ ◎ ○ ◎ ○ ○ ○ ○ Table 2

Comparative Example 1 Example 1 Oxygen transfer rate 250 150 (cc/m ² /day) Water vapor transfer rate 3.0 2.4 (g/m ² /day) Adhesion strength to Al 30 60 (g/10mm) (% growth ) 100 200 Gloss ○ ◎The above Table 1 and Table 2 are carried out by the following method (1) Film structure———

← Biaxially oriented polypropylene (20μm)———

← Polyethylene (extrusion laminated, 13-15μm)———

← Upper Al metal———

←Casted polypropylene (25μm)————(2) Adhesion strength to Al

A strength between polyethylene (13-15μm) and metal-cast polypropylene

Tensile testing machine, beam speed: 300mm/min—% increase: % increase compared with Comparative Example 1—glossiness: ◎excellent

○average

Claims (6)

1. co-extrusion cast polypropylene film that is used for the Al metal is characterized in that it comprises:

A) central core, it comprises the thermoplasticity isotactic polypropylene;

B) described central core superficial layer, it comprises heat sealable polypropylene copolymer;

C) another superficial layer of described central core, it comprises thermoplasticity isotactic homo-polypropylene or polypropylene copolymer and with polypropylene the polar material of good miscibility is arranged as Al metal level on the vacuum, described polar material is for being selected from ethylene vinyl acetate copolymer, ethylene acrylic acid co polymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate copolymer, ionomer, polyester elastomer, polyisobutene acid methyl terpolymer, maleic anhydride or acetate polymers grafted or their blend.

2. co-extrusion cast polypropylene film as claimed in claim 1 is characterized in that, described central core is for only containing the isotactic homo-polypropylene that antioxidant and chlorine are captured agent.

3. co-extrusion cast polypropylene film as claimed in claim 1, it is characterized in that, described polypropylene copolymer is for being selected from ethylene-propylene, the random copolymer of butylene-propylene or propylene-octene, or a kind of in the trimer of ethylene-propylene-butylene or ethylene-propylene-octene.

4. co-extrusion cast polypropylene film as claimed in claim 1 is characterized in that, can add at least a polyterpene that is selected from, the polymeric material of polybutene or acyclic hydrocarbons polymer or its concurrent mixture on described vacuum in the Al metal level.

5. co-extrusion cast polypropylene film as claimed in claim 1 is characterized in that the gross thickness of described film is in the scope of 10-100 μ m.

6. co-extrusion cast polypropylene film as claimed in claim 1 is characterized in that the Al metal layer thickness is in the scope of 25-500 on the vacuum.