Adhesive composition based on ethylene copolymers obtained by tube copolymerisation, that can be used for extrusion-coating and extrusion-lamination

Abstract

An adhesive composition of at least one ethylene polymer or copolymer, wherein at least one first polymer or copolymer including the unsaturated carboxylic acid ester type comonomer is copolymerized in a continuous high-pressure tubular reactor, while a second polymer or copolymer including the functional comonomer is copolymerized by either autoclave or tubular continuous high-pressure radical means; the first and second polymer or copolymer possibly being of one and the same polymer/copolymer. Also, a multilayer structure that incorporates the adhesive composition and a particular process for obtaining this composition.

Claims

1. An adhesive composition comprising at least one first copolymer, wherein the first copolymer comprises: ethylene comonomers and unsaturated carboxylic acid ester comonomers comprising methyl acrylates, and comprising at least one second copolymer blended with the first copolymer, wherein the second copolymer comprises: ethylene comonomers, unsaturated carboxylic acid ester comonomers comprising methyl acrylates, and functional comonomers comprising an anhydride function and optionally at least one reactive function selected from the group consisting of an acid function and an epoxide function, wherein said composition comprising at least 5% by weight of said unsaturated carboxylic acid ester comonomers relative to the weight of said composition and less than 2% by weight of the functional comonomers relative to the weight of said composition, wherein the first copolymer is obtained by copolymerization carried out at a temperature between 210° C. and 240° C. in a continuous high-pressure tubular reactor and the second copolymer is obtained by copolymerization carried out at a temperature between 190° C. and 220° C. in a continuous high-pressure autoclave reactor, wherein the weight ratio between the first copolymer and the second copolymer is between 98:2 and 40:60, wherein the composition can adhere onto a printed support by an extrusion-coating process, and wherein the printed support is selected from a printed polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) or polyacrylonitrile (PAN) film.

2. The adhesive composition as claimed in claim 1, comprising less than 1% by weight of the functional comonomers relative to the weight of said composition.

3. The adhesive composition as claimed in claim 1, wherein the unsaturated carboxylic acid ester comonomers further comprise: alkyl methacrylates, the alkyl group comprising from 1 to 24 carbon atoms.

4. The adhesive composition as claimed in claim 1, wherein the functional comonomers are maleic anhydride.

5. The adhesive composition as claimed in claim 1, comprising from 0.15% to 0.6% by weight of the functional comonomers relative to the weight of said composition.

6. The adhesive composition as claimed in claim 1, comprising from 10% to 40% by weight of the unsaturated carboxylic acid ester comonomers relative to the weight of said composition, said unsaturated carboxylic acid ester comonomers further comprising: alkyl methacrylates, the alkyl group comprising from 1 to 24 carbon atoms.

7. A method preparing a multilayer structure with the adhesive composition as defined in claim 1, the method comprising forming said multilayer structure with the adhesive composition, said multilayer structure comprising at least one layer of a support, said support being selected from the group consisting of aluminum, paper, board, cellophane, or films, wherein the films are based on polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) and polyacrylonitrile (PAN) resins, the films optionally being oriented, metalized, printed, or treated by physical or chemical means, and wherein the films are also coated with an inorganic barrier layer comprising SiOx or AlOx.

8. A multilayer structure comprising: at least one layer of an adhesive composition as defined in claim 1, and at least one layer of a support, said support being selected from the group consisting of aluminum, paper, board, cellophane, and films, wherein the films are based on polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) or polyacrylonitrile (PAN) resins, the films optionally being oriented, metalized, printed, or treated by physical or chemical means, wherein the films are coated with an inorganic barrier layer comprising SiOx or AlOx.

9. The adhesive composition as claimed in claim 1, comprising from 15% to 25% by weight of the unsaturated carboxylic acid ester comonomers relative to the weight of said composition, said unsaturated carboxylic acid ester comonomers further comprising: alkyl methacrylates, the alkyl group comprising from 1 to 24 carbon atoms.

Description

EXAMPLES OF IMPLEMENTATION

(1) The structures are produced by extrusion coating or lamination on a COLLIN laboratory line.

(2) The adhesion of the binders is evaluated during a peel test at 200 mm/min (millimeters per minute) on a Synergie 200H tensile testing machine equipped with a 100 N (Newton) load cell.

(3) Ink 1=White

(4) Ink 2=Red 1

(5) Ink 3=Green 1

(6) Ink 4=Blue

(7) Ink 5=Red 2 (different type to ink 2)

(8) Ink 6=Green 2 (different type to ink 3)

(9) Binders or resins of different compositions (the overall characteristics of which are specified in the table below) were used in the various examples.

(10) TABLE-US-00001 MAH (maleic Acrylate anhydride, % (% by by weight of Nature of the weight of the the Reference binder composition) composition) MFI Resin 1 Autoclave EMA 24 0 7 Resin 2 Tubular EMA 24 0 5.4 Resin 3 Autoclave 20 0.3 8 terpolymer Resin 4 Tubular 25 0.3 7.3 terpolymer Resin 5 Mixture (SA) 23 0.3 6 Resin 6 Mixture (AA) 23 0.3 6

(11) The MFI (Melt Flow Index) was measured using a dead-weight extrusion plastometer according to the ISO 1133 standard, at a temperature of 190° C. and under a weight of 2.16 kg. The result is expressed in grams/10 minutes.

(12) Resins 1 and 2 (EMA) are ethylene/methyl acrylate copolymers obtained by continuous high-pressure radical copolymerization, respectively according to an autoclave process at a temperature of 205° C. and a pressure of 1690 bar (1) and a tubular process (2) at a temperature of 230° C. and a pressure of 2500 bar.

(13) Resin 3 is an ethylene/methyl acrylate/maleic anhydride terpolymer obtained by (continuous) high-pressure radical copolymerization according to an autoclave process at a temperature of 205° C. and a pressure of 1690 bar.

(14) Resin 4 is an ethylene, methyl acrylate and maleic anhydride terpolymer obtained by (continuous) high-pressure radical copolymerization according to a tubular process at a temperature of 205° C. and a pressure of 2200 bar.

(15) Resins 5 and 6 are obtained by blending, on an extruder, an ethylene and methyl acrylate copolymer obtained by (continuous) high-pressure radical polymerization according to a tubular process at a temperature of 230° C. and a pressure of 2500 bar and an ethylene, methyl acrylate and maleic anhydride terpolymer obtained by autoclave high-pressure radical polymerization (at a temperature of 205° C. and a pressure of 1690 bar).

(16) Resin 6 (denoted AA), unlike resin 5 (denoted SA) additionally comprises a mixture of additives for the processability (preventing bonding to the “chill roll”).

(17) Resins 4, 5 and 6 are resins according to the invention.

(18) In the following, the “binder” denotes the composition tested, mainly in adhesion.

Example 1

(19) This example shows that on a metalized support, the maleic anhydride of the terpolymer is essential for obtaining adhesion and that the tubular terpolymer performs better than the autoclave (high-pressure) terpolymer.

(20) Structure=VmPET/binder/LDPE (12 μm/10 μm/30 μm)

(21) LDPE: low-density polyethylene

(22) VmPET: vacuum metalized PET film

(23) EMA: ethylene methacrylate

(24) TABLE-US-00002 VmPET/binder/LDPE at 290° C. Peel force (N/15 mm) after 8 Binder days Resin 1 <0.5 Resin 2 <0.5 Resin 3 1.5 Resin 4 1.5 Resin 5 2.5

Example 2

(25) This example shows the improvement in the adhesion obtained on the ink 1 by using a tubular EMA/autoclave EMA (comparison of tubular EMA relative to an autoclave EMA) and also by using a terpolymer/EMA and more remarkably by using a terpolymer derived from a tubular high-pressure (HP) polymerization/other binders.

(26) Structure=OPET/ink/binder/LDPE (12 μm/1 μm/10 μm/30 μm)

(27) TABLE-US-00003 OPET/ink 1/binder/LDPE at 295° C. Peel force (N/15 mm) after 30 Binder days Resin 1 1.6 Resin 2 2.5 Resin 3 2.5 Resin 4 3.1 Resin 5 3.1

Example 3

(28) This example shows the improvement in the adhesion obtained on OPET by using a terpolymer/tubular EMA and more remarkably by using a terpolymer from a tubular HP polymerization/other binders.

(29) Structure=OPET/binder/LDPE (12 μm/10 μm/30 μm)

(30) TABLE-US-00004 OPET/binder/LDPE at 290° C. Peel force (N/15 mm) Binder t.sub.0 t.sub.0 + 8 d (days) Resin 2 3.2 3.9 Resin 3 2.2 4.6 Resin 6 3.9 6

Example 4

(31) This example shows the improvement in the adhesion obtained on the inks 2 & 3 by using a terpolymer/tubular EMA and more remarkably by using a terpolymer from a tubular HP polymerization/other binders.

(32) Structure=OPET/ink/binder/LDPE (12 μm/1 μm/10 μm/30 μm)

(33) TABLE-US-00005 OPET/ink 2/binder/ OPET/ink 3/binder/ LDPE 290° C. LDPE 290° C. Binder t.sub.0 t.sub.0 + 8 d t.sub.0 t.sub.0 + 8 d Resin 2 2.3 1.7 2.8 2 Resin 3 1.5 2.7 1.7 2.6 Resin 5 3.4 3.7 3.1 3.3

Example 5

(34) This example again shows the advantage of a tubular terpolymer relative to an EMA for the adhesion to ink but this time with a BOPP (Biaxially Oriented PolyPropylene) support.

(35) Structure=BOPP/ink/binder/LDPE (20 μm/1 μm/10 μm/50 μm)

(36) TABLE-US-00006 BOPP/ink 4/binder/LDPE at 290° C. Peel force (N/15 mm) Binder t.sub.0 t.sub.0 + 8 d Resin 2 2.9 2 Resin 6 3.4 2.7

Example 6

(37) This example demonstrates the improvement in the adhesion and the ultra-versatility of the formulation according to the invention. Specifically, it makes it possible to combine, in extrusion-lamination, various substrates of very different natures that EMAs do not permit. It also makes it possible to obtain higher peel forces on ink than the conventional version of the terpolymer obtained with an autoclave process.

(38) Structures:

(39) 1: OPET/binder/Alu (12 μm/20 μm/37 μm)

(40) 2: OPET/binder/VmPET (12 μm/20 μm/12 μm)

(41) 3: BOPP/ink 5/binder/vmPET (20 μm/1 μm/20 μm/12 μm)

(42) TABLE-US-00007 OPET/ OPET/ binder/ binder/ vmPET Alu 12/20/12 μm at 12/20/37 μm 310° C. at 310° C. Peel force Peel force (N/15 mm) (N/15 mm) (failure BOPP/ink 5/ (failure at the binder/vmPET at the binder/ 20/20/12 μm at binder/alu vmPET 310° C. Peel interface) interface) force (N/15 mm) binder t.sub.0 t.sub.0 + 8 d t.sub.0 t.sub.0 + 8 d t.sub.0 t.sub.0 + 8 d Resin 3 7.9 9.2 6 9 0.3 0.4 (ink// (ink// binder) binder) Resin 6 6 5.7 5 6.6 uninitiatable since force too high Resin 1 or 0.7 0.5 0.4 0.3 0.5 0.6 2 (binder/ (binder/ VmPET) VmPET)

Example 7

(43) This example shows the improvement in the adhesion obtained with our new formulation relative to that obtained with the conventional formulation at “low” temperature.

(44) Structure:

(45) PP woven fabric/PP+LDPE/binder/ink 6/BOPP (100 μm/15 μm/1 μm/5 μm/20 μm)

(46) TABLE-US-00008 PP woven fabric/PP + LDPE/binder/ink 6/BOPP (100/15/5/20 μm) 290° C. 320° C. t > t > Binder t0 30 days interface t0 30 days interface Resin 3 1.6 2 Binder//ink 3.5 3 PP woven fabric// PP + LDPE Resin 6 2.1 4.9 PP woven 3.5 3.2 PP woven fabric// fabric// PP + LDPE PP + LDPE