WATER BORNE DRY LAMINATION BONDING AGENT WITH HEAT RESISTANCE IMPROVEMENT

Abstract

The present disclosure is directed to a two-component bonding agent composition and a process for applying a layer of the bonding agent composition to substrate layers to make laminates.

Claims

1. A two-component bonding agent composition comprising: (a) a first component that is an aqueous mixture with its solid portion comprising (i) 0.1% to 10% of a polyol containing at least two hydroxyl groups and being selected from the group consisting of water dispersible polyether polyols, polyester polyols, polyether polyester polyols and mixtures thereof, (ii) 3% to 32% of a rosin resin, and (iii) 58% to 96% of a polymer having from 20-60% residues of at least one styrene monomer, from 40-80% residues of at least one acrylic monomer having a Tg less than 0 C., from 1-4% residues of (meth)acrylic acid and less than 0.5% residues of hydroxyl-containing monomers; and (b) a second component comprising a water dispersible polyisocyanate, wherein the second component is present relative to the first component at a NCO/NCO-reactive group molar ratio of 1:1 to 8:1.

2. The composition according to claim 1, wherein the polymer has a weight average molecular weight of between 5,000 and 2,000,000.

3. The composition according to claim 1, wherein the polyol is polypropylene glycol.

4. The composition according to claim 1, wherein the polyol has a number average molecular weight from 100 to 7,500.

5. The composition according to claim 1, wherein the rosin resin is selected from modified rosins, hydrogenated rosins, disproportionated rosins and polymerized rosins obtained respectively by modifying, hydrogenating, disproportionating and polymerizing raw material rosins, and rosin esters obtained by esterifying raw material rosins with alcohols or an epoxy compound.

6. The composition according to claim 5, wherein the modified rosin resins are selected from unsaturated modified rosins obtained by modifying raw material rosins with unsaturated acid, and phenolic modified rosins obtained by modifying raw material rosins with phenols.

7. The composition according to claim 6, wherein the unsaturated acids are acrylic acid, methacrylic acid, fumaric acid, and maleic acid.

8. The composition according to claim 6, wherein the phenols are phenol and alkylphenol.

9. The composition according to claim 5, wherein the alcohol is glycerin.

10. The composition according to claim 5, wherein the alcohol is pentaerythritol.

11. The composition according to claim 1, wherein the rosin resin has a molecular weight of from 1,000 to 50,000.

12. The composition according to claim 1, wherein the rosin resin has an acid value of from 1 to 50 KOH mg/g.

13. The composition according to claim 1, wherein the rosin resin has a softening point of from 25 C. to 200 C.

14. The composition according to claim 1 wherein the polyisocyanate is selected from polyisocyanates based on toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenyl methane diisocyanate, dicyclohexyl methane diisocyanate, isomers thereof, and mixtures thereof.

15. A process for making a laminated article wherein at least two substrate layers are bonded together by a layer of a bonding agent, comprising bonding said at least two substrate layers with the bonding agent composition of claim 1.

16. A laminate bonding at least two substrate layers by the bonding agent composition of claim 1.

Description

EXAMPLES

[0033] I. Raw Materials

[0034] Films: Substrates used in the Examples include biaxially oriented polypropylene film (BOPP, thickness 18 m), vacuum metallized casted polyethylene terephthalate polyester film (VMPET, thickness 12 m) films, and polyethylene film (PE, thickness 60 m) as commercially obtained from Guangdong Nan Cheng Company.

[0035] Ingredients used in the Examples include those listed in Table 1 below.

TABLE-US-00001 TABLE 1 Ingredients Used In Examples Ingredients Commercial name Solids Supplier Acrylic BA-Styrene copolymer 44.0% Dow copolymer of 60% BA monomer and 38% styrene monomer Polyol Polyether diol 100% Dow Hard Rosin SUPER ESTER E-865NT 50.0% Arakawa resin Poly- HORDAMER PE35 37.5% BYK olefin AQUACER 593 30.0% BYK Poly- COREACTANT CR 3A >99.8% Dow isocyanate

[0036] II. Test Methods

[0037] The water based adhesives and BOPP, VMPET, PE films are used without any pre-treatment. The adhesives are coated to BOPP films and combined with VMPET films to obtain BOPP/VMPET 2-layer laminates in an amount of 2.0 g/m.sup.2 by dry weight and dried. The 2-layer laminates are then coated with the water based adhesives in an amount of 2.0 g/m.sup.2 by dry weight and combined with PE films to obtain BOPP/VMPET/PE 3-layer laminates. The BOPP/VMPET/PE 3-layer laminates are cured at 50 C. for 2 days and then tested.

[0038] i) Bond Strength (BS):

[0039] The laminates of the present disclosure are cut into 25 mm width10 cm length strips using metal stencil for T-peel test under 250 mm/min crosshead speed using a 5943 Series Single Column Table Top System available from Instron Corporation. During the test, the tail of each strip is pulled slightly by fingers to make sure the tail remained 90 degrees to the peeling direction. Three strips for each sample are tested and the average value is calculated. Results are in the unit of N/15 mm. The higher the value is, the better the bond strength is.

[0040] ii) Heat Seal Strength (HS)

[0041] The laminates are heat-sealed in a HSG-C Heat-Sealing Machine available from Brugger Company under 140 C. seal temperature and 300N pressure for 1 second (or under 220 C. seal temperature and 300N pressure for 0.5 second), then cooled down and cut into 25 mm width10 cm length strips for heat seal strength test under 250 mm/min crosshead speed using a 5943 Series Single Column Table Top System available from Instron Corporation. Three strips for each sample are tested and the average value is calculated. Results are in the unit of N/15 mm. The higher the value is, the better the heat seal strength is.

[0042] III. Examples:

[0043] 470.25 g of acrylic copolymer emulsion (BA-Styrene copolymer with solids of 44%) is placed in a 1 liter bottle with a magnetic stirrer, then 4.75 g of polyol (polyether diol) and 25 g of SUPER ESTER E-865NT rosin resin are poured into the bottle and stirred for 20 minutes. When the blending composition is distributed, 10 g of COREACTANT CR 3A polyisocyanate is drop added into the mixture emulsion and the mixture is stirred for another 20 minutes.

[0044] Illustrative Adhesive Examples IE1, IE2, IE3 and IE4, and Comparative Adhesive Examples CE1, CE2 and CE3 are prepared with the ingredients listed in Table 1. The same blending process as described above is repeated for each Example but with ingredients according to the compositions listed in Table 2.

TABLE-US-00002 TABLE 2 Example Compositions CE1 IE1 IE2 IE3 IE4 CE2 CE3 BA-Styrene copolymer 98% 88.2% 78.4% 94% 68.6% 88.2% 88.2% Polyether diol 2% 1.8% 1.6% 1% 1.4% 1.8% 1.8% SUPER ESTER E-865NT 10% 20% 5% 30% HORDAMER PE35 10% AQUACER 593 10% COREACTANT CR 3A* 2% 2% 2% 2% 2% 2% 2% *% based on the total weight of component A.

[0045] Illustrative Adhesive Examples IE1, IE2 and Comparative Adhesive Example CE1 are each coated to VMPET and PE60 films to obtain VMPET/PE60 2-layers laminates for further tests.

[0046] Illustrative Adhesive Examples IE1, IE2, IE3 and IE4, and Comparative Adhesive Example CE1, CE2 and CE3 are each coated to BOPP, VMPET and PE60 films to obtain BOPP/VMPET/PE60 laminates for further tests.

[0047] IV. Results

[0048] As shown in Table 3, Illustrative Adhesive Examples IE1 and IE2 have significantly improved seat seal strength at 140 and 220 C., compared to that of Comparative Adhesive Example 1.

TABLE-US-00003 TABLE 3 Performance Results Heat Seal Heat Seal Mode of Sample Bonding Strength Strength Failure in Heat Structure No. Strength (140 C.-1 s) (220 C.-0.5 s) Seal Test VMPET/PE60 CE1 2.62 31.2 27.5 Lamination Tear IE1 2.52 31.6 34.7 Lamination Rigid broken IE2 2.49 33.9 35.2 Lamination Rigid broken

[0049] As shown in Table 4, Illustrative Adhesive Examples IE1, IE2, IE3 and IE4 have significantly improved heat seal strength at 220 C., compared to those of Comparative Adhesive Examples CE1, CE2 and CE3.

TABLE-US-00004 TABLE 4 Performance Results Sam- Bonding Strength Heat Seal Strength Mode of ple BOPP/ VMPET/ 140 C.- 220 C.- Failure Structure No. VMPET PE 1 S HS 0.5 S HS in HS Test BOPP/ CE1 1.89 2.73 40.12 39.09 Lamination VMPET/ Tear PE60 IE3 2.02 2.61 38.32 41.43 Lamination Rigid Broken IE1 2.12 2.61 41.63 48.75 Lamination Rigid Broken IE2 1.89 2.33 37.27 42.70 Lamination Rigid Broken IE4 1.61 2.45 39.41 45.27 Lamination Rigid broken CE2 1.90 2.62 39.12 37.78 Lamination Rigid broken CE3 1.86 2.30 32.75 44.56 Lamination Rigid Broken