METHOD OF MAKING FILM LAMINATES USING AMINE-REACTIVE ACRYLIC LAMINATION ADHESIVES

Abstract

A description is given of a method of making film laminates using a lamination adhesive comprising (a) at least one acrylic polymer A with anhydride groups which are reactive with primary or secondary amine groups; and (b) at least one compound B with at least two amine groups selected from primary and secondary amine groups. The acrylic polymer A has a molecular weight of from 3000 to 50000 and the lamination adhesive is free of organic solvents, free of water and free of compounds with isocyanate groups.

Claims

1.-16. (canceled)

17. A method of making film laminates, the method comprising the steps of (i) coating a film substrate with at least one lamination adhesive; and (ii) laminating the coated film onto a substrate; wherein the lamination adhesive is a two-component, solventless adhesive and comprises (a) a first component comprising at least one acrylic polymer A with anhydride groups which are reactive with primary or secondary amine groups; and (b) a second component comprising at least one compound B with at least two amine groups selected from primary and secondary amine groups; wherein the acrylic polymer A has a weight average molecular weight of from 3000 to 50000; wherein the lamination adhesive is free of organic solvents, free of water and free of compounds with isocyanate groups.

18. Method according claim 17, wherein compound B is selected from the group consisting of organic diamines, polyether amines and polyethylene imines.

19. Method according to claim 17, wherein the acrylic polymer is made by continuous radical polymerization at a temperatures from 160 to 300° C.

20. Method according to claim 17, wherein the acrylic polymer is made of (a) from 85 to 99 wt. % of at least one alkyl(meth)acrylate monomer which, when polymerized as homopolymer has a glass transition temperature below 0° C., measured by Differential Scanning Calorimetry according to ASTM D 3418-08 as the midpoint temperature of the second heating curve at a heating rate or 20° C./min; (b) from 1 to 15% by weight of at least one monomer with at least one anhydride group which is reactive with primary or secondary amine groups; (c) optionally from 0 to 9% by weight of at least one monomer different from monomers (a) and (b); wherein the fully reacted lamination adhesive has a modulus of elasticity G′ of from more than 0.1 and up to 1 MPa at 23° C., measured by dynamic-mechanical thermo-analysis.

21. Method according to claim 20, wherein the acrylic polymer is made by radical polymerization of monomers comprising (a) from 85 to 99 wt. % of at least one alkyl(meth)acrylate monomer selected from the group consisting of C2 to C10 alkyl acrylates, (b) from 1 to 15% by weight of at least one monomer with at least one anhydride group.

22. Method according to claim 17, wherein the uncrosslinked acrylic polymer has a glass transition temperature of from −60° C. to −5° C., measured by Differential Scanning Calorimetry according to ASTM D 3418-08 as the midpoint temperature of the second heating curve at a heating rate or 20° C./min.

23. Method according to claim 17, wherein the molar ratio of the anhydride groups of polymer A which are reactive with primary or secondary amine groups to the primary or secondary amine groups of compound B is from 0.5 to 2.0.

24. Method according to claim 17, wherein the polymer A is made by a polymerization process wherein the relative amount of anhydride monomers in the monomer mixture is higher at an early stage of the polymerization and lower at a later stage of polymerization.

25. Method according to claim 17, wherein the viscosity of the adhesive is less than 500 Pa s; measurement method ISO 2721-10 at 40° C. and shear rate of 100 l/s; and/or wherein the adhesive is coatable on substrate films with roll coaters at temperatures of 40° C. or lower.

26. Method according to claim 17, wherein the peel strength of a film-to-film laminate of two polyethylene terephthalate films is at least 0.4 N/15 mm at 23° C. and after 24 hours storage at 23° C.

27. Method according to claim 17 wherein the coating temperature is 40° C. or less and wherein the adhesive is not crosslinked by UV radiation.

28. A method comprising providing a lamination adhesive and making film laminates, wherein the lamination adhesive is a two-component, solventless adhesive and comprises (a) a first component comprising at least one acrylic polymer A with anhydride groups which are reactive with primary or secondary amine groups; and (b) a second component comprising at least one compound B with at least two amine groups selected from primary and secondary amine groups; wherein the acrylic polymer A has a weight average molecular weight of from 3000 to 50000; wherein the lamination adhesive is free of organic solvents, free of water and free of compounds with isocyanate groups.

29. A film laminate wherein a film is bonded to a substrate wherein the film laminate is a product of the method according to claim 17.

30. The film laminate according to claim 29 wherein the laminate is a film-to-film laminate having a first polymeric film and at least one of a second polymeric film or a metal film.

31. The film laminate according to claim 30, wherein the material of the first film is selected from the group consisting of polyethylene, oriented polypropylene, undrawn polypropylene, polyamide, polyethylene terephthalate, polyacetate, cellophane; and wherein the material of the second film is selected from the group consisting of polyethylene, oriented polypropylene, undrawn polypropylene, polyamide, polyethylene terephthalate, polyacetate, cellophane, metalized films and metal foils.

32. The film laminate according to claim 30, wherein the first and the second films are bonded to one another with the lamination adhesive so firmly that the peel strength, measured 24 h after laminate production and at 23° C. and 50% relative humidity, is 0.4 N/15 mm or more.

Description

EXAMPLES

Abbreviations

[0110] BA n-butyl acrylate [0111] EA ethyl acrylate [0112] MAH maleic acid anhydride [0113] EHA 2-ethylhexyl acrylate [0114] MMA methyl methacrylate [0115] STY styrene [0116] GMA glycidyl methacrylate [0117] pphm parts per hundred monomers (parts by weight per 100 parts by weight of monomers) [0118] PET polyethylene terephthalate

[0119] Measurement of Polymer Molecular Weight by GPC:

[0120] To measure molecular weight of the example polymers described below, the polymeric resin was first dissolved in a solution of tetrahydrofuran (THF) solvent then injected into a Gel Permeation Chromatogram (Waters 2695 instrument coupled with Waters 2410 Refractive Index Detector). One pair of PLGEL MIXED B columns with one guard column was used and Millennium software was used to determine the number average molecular weight (Mn), weight average molecular weight (Mw) and z average molecular weight (Mz) of the polymer.

[0121] Measurement of Modulus of Elasticity G′:

[0122] The modulus of elasticity G′ was measured on polymer films with a thickness of approximately 0.8 to 1.0 mm. The measurements are made by means of dynamic-mechanical thermo-analysis (DMTA). Measuring instrument: deformation-controlled modular rheometer system Ares; Parallel-Plate geometry with 8 mm diameter. Dynamic shear modulus, measurement frequency 1 Hz, heating rate 2° C./min, measuring temperature −20° C. to +200° C.

[0123] Method of Polymerization:

Examples 4 to 6

[0124] High temperature polymerization (190° C.) that is run in a continuously stirred tank reactor with acetone as solvent and monomer mixtures as described in table 1. The solvent is removed by distillation after polymerization.

[0125] Polymerization initiator: di-tert-butyl peroxide

Examples 1 to 3

[0126] The reaction temperature was 80° C. in methyl ethyl ketone solvent.

[0127] Polymerization initiator: tert-butyl peroxypivalate.

[0128] The solvent is removed by distillation after polymerization.

TABLE-US-00001 TABLE 1 Acrylic polymers Viscosity at Monomers Tg 23° C. Example Parts by weight [° C.]** [Pa s] Mw Example 1 .sup.  65 BA, 30 EA, 5 MAH   −30° C. 140 Pa s 25000 Example 2 .sup.  97.5 EHA, 2.5 MAH   −59° C. 110 Pa s 30000 Example 3 .sup.  95 EHA, 5 MAH   −57° C.  90 Pa s 16900 Example 4 .sup.  95 BA, 5 MAH   −40° C. 100 Pa s 14218 Example 5*.sup.) 83 BA, 17GMA   −25° C. 120 Pa s 15380 Example 6 .sup.  77 BA, 12 MMA, 11 MAH −27.9° C.  4411 *.sup.)comparative **calculated by FOX-equation

[0129] Two-Component Laminations Adhesives:

[0130] Two-component lamination adhesives were formed from the acrylic polymers of table 1 with amines according to table 2.

[0131] Preparation of Film-to-Film Laminates:

[0132] Acrylic polymers A were mixed with equimolar amounts of amines, based on amounts of anhydride groups.

[0133] The mixtures are knife-coated in a dry film thickness of 3 μm onto a first PET-film with thickness of 36 μm. The coated films are laminated to a second PET-film with thickness of 36 μm under a pressure of 6.5 bar and at 23° C. in a roller press at 5 m/min. The composite films are subsequently stored for 1 day at room temperature under standard conditions (23° C.; 50% relative humidity).

[0134] Measurement of Peel Strength:

[0135] Following storage of the laminate for 24 h at room temperature the laminate is cut into strips 15 millimeters wide. The laminate strip is pulled apart on a Zwick tensile testing machine and the force required to achieve this is recorded. The test takes place on a tensile testing machine at an angle of 90 degrees (T-test) and a removal velocity of 100 mm/min. The test strip is opened up on one side, with one of the resultant ends being clamped into the upper jaw and the other into the lower jaw of the tensile testing machine, and the test is commenced. The result reported is the average maximum of the force from 3 individual measurements, in N/15 mm.

[0136] The results are shown in table 2.

TABLE-US-00002 TABLE 2 Results of the peel test measurements Peel strength after 24 h Acrylic polymer Amine [N/15 mm] Example 7 .sup.   Example 1 4,7,10-trioxatridecane- 0.5 BA/EA/MAH 1,13-diamine Example 8 .sup.   Example 1 95 pts by weight 1.0 BA/EA/MAH 4,7,10-trioxatridecane- 1,13-diamine 5 pts by weight Lupasol ® FG.sup.(1) Example 9 .sup.   Example 2 Polyetheramine D 2000.sup.(2) 0.8 EHA/MAH Example 10 .sup.  Example 3 Polyetheramine D 230.sup.(3) 0.4 EHA/MAH Example 11 .sup.  Example 4 Polyetheramine D 230.sup.(3) 0.7 BA/MAH Example 12*.sup.)  .sup. Example 5*.sup.) 4,7,10-trioxatridecane- 0.1 BA/GMA 1,13-diamine Example 13 .sup.  Example 6 Polyetheramine D 230.sup.(3) .sup.   5.1.sup.(4) BA/MMA/MAH *.sup.)comparative .sup.(1)polyethyleneimine (PEI), average molecular weight 800, viscosity 800-5000 mPa s at 20° C. .sup.(2)difunctional primary amine with polyoxypropylene backbone, average molecular weight about 2000. .sup.(3)difunctional primary amine with polyoxypropylene backbone, average molecular weight about 230. .sup.(4)lamination between 19 μm PET film and 30 μm BOPP film