Polyurethane Laminating Adhesive Containing Filler

Abstract

The present invention relates to a polyurethane adhesive, in particular for laminating multilayer films, wherein the PU adhesive containsbased on the total weight of the adhesive5 to 50 wt %, preferably 10 to 40 wt %, particularly preferably 20 to 30 wt % of at least one solid particulate filler, wherein at least 90% of the filler particles of the at least one filler has a particle size of 4 m or less, and the at least one filler has a Mohs hardness of 3 or less. The present invention also relates to the use of the adhesive for adhering films, to methods for producing composite films, and to composite films adhered using the aforementioned adhesive.

Claims

1. A polyurethane-based laminating adhesive composition, comprising an isocyanate functional component; an isocyanate reactive component; and 5 to 50 wt %, relative to the total weight of the laminating adhesive composition, of at least one solid particulate filler, wherein, i) at least 90% of the filler particles of the at least one solid particulate filler have a particle size of 4 m or less, and ii) the at least one solid particulate filler has a Mohs hardness of 3 or less.

2. The laminating adhesive composition according to claim 1, containing 10 to 40 wt % of at least one solid particulate filler.

3. The laminating adhesive composition according to claim 1, containing 20 to 30 wt % of at least one solid particulate filler.

4. The laminating adhesive composition according to claim 1, comprising a molar ratio of NCO groups to OH groups of 1:1 to 1.8:1.

5. The laminating adhesive composition according to claim 1, comprising a molar ratio of NCO groups to OH groups of 1.05:1 to 1.5:1.

6. The laminating adhesive composition according to claim 1, wherein the at least one filler has a particle size distribution of 100.3 m, 501.5 m, and 904 m.

7. The laminating adhesive composition according to claim 1, wherein the at least one filler has an oil absorption value of 50 or less.

8. The laminating adhesive composition according to claim 1, wherein the at least one filler has an oil absorption value of 40 or less.

9. The laminating adhesive composition according to claim 1, wherein the filler is selected from the group consisting of calcium carbonate, calcium sulfate, dolomite, and mixtures thereof.

10. The laminating adhesive composition according to claim 1, wherein the laminating adhesive composition is a two-component polyurethane adhesive, and a) the isocyanate reactive component comprises a hydroxy-terminated polyurethane prepolymer and the isocyanate functional component comprises a polyisocyanate, or b) the isocyanate functional component comprises an isocyanate terminated polyurethane prepolymer and the isocyanate reactive component comprises a polyol.

11. The laminating adhesive composition according to claim 1, wherein the filler is contained either in the isocyanate functional component or in the isocyanate reactive component.

12. The laminating adhesive composition according to claim 1, wherein: a) the composition further contains at least one catalyst selected from Sn- or Ti-based metal catalysts or amine catalysts, and/or b) the composition has a viscosity of 500 to 100,000 at a temperature of 40 C., and/or c) the composition contains a filler having a maximum 5% content of filler particles with a particle size 0.1 m, relative to the filler, and/or d) the composition is essentially free of organic solvents.

13. The laminating adhesive composition according to claim 1, wherein: a) the composition further contains at least one catalyst selected from Sn- or Ti-based metal catalysts or amine catalysts, and/or b) the composition has a viscosity of 1,000 to 20,000 mPas at a temperature of 40 C., and/or c) the composition contains a filler having a maximum 5% content of filler particles with a particle size 0.1 m, relative to the filler, and/or d) the composition is essentially free of organic solvents.

14. A multilayer film comprising a plurality of polymeric films or metal foils bonded together by the laminating adhesive composition according to claim 1.

15. A packaging for medicines or foodstuffs comprising the multilayer film of claim 11 sealed around a medicine or a foodstuff.

16. A method for producing composite films, comprising: providing a first substrate having a surface; disposing the polyurethane-based laminating adhesive composition of claim 1 on at least part of the first substrate surface; providing a second substrate having a surface; laminating the second substrate surface over the first substrate surface wherein the polyurethane-based laminating adhesive composition is in contact with at least portions of both the first substrate surface and the second substrate surface; and curing the polyurethane-based laminating adhesive composition to bond the first substrate to the second substrate.

17. The method according to claim 13, wherein the polyurethane-based laminating adhesive composition of claim 1 is disposed in an amount of 1 to 5 g/m.sup.2 on the first substrate surface.

Description

EXAMPLES

Example 1 (According to the Present Invention)

[0069] Resin base:

[0070] NCO-terminated MDI prepolymer with an NCO content of 10 to 15 wt %.

[0071] Curing agent:

[0072] 30 wt % trifunctional polypropylene glycol (PPG) with Mw=1000 g/mol; 5 wt % trifunctional PPG with Mw=450 g/mol; 5 wt % dipropylene glycol; 60 wt % calcium carbonate (50.1 m, 100.3 m, 501.5 m, and 904 m).

[0073] Resin:curing agent mixing ratio: 100:120 parts by weight

[0074] Filler content in the mixture: 27 wt %

Example 2 (According to the Present Invention)

[0075] Resin base:

[0076] NCO-terminated MDI prepolymer with an NCO content of 10 to 15 wt %.

[0077] Curing agent:

[0078] 20 wt % trifunctional polypropylene glycol (PPG) with Mw=1000 g/mol; 20 wt % difunctional polyester with Mw=2000 g/mol; 5 wt % trifunctional PPG with Mw=450 g/mol; 5 wt % dipropylene glycol; 50 wt % calcium carbonate (50.1 m, 100.3 m, 501.5 m, and 904 m).

[0079] Resin:curing agent mixing ratio: 100:100 parts by weight

[0080] Filler content in the mixture: 25 wt %

Example 3 (Comparative Example)

[0081] Resin base:

[0082] NCO-terminated MDI prepolymer with an NCO content of 10 to 15 wt %.

[0083] Curing agent: 30 wt % trifunctional polypropylene glycol (PPG) with Mw=1000 g/mol; 30 wt % difunctional polyester with Mw=2000 g/mol; 5 wt % trifunctional PPG with Mw=450 g/mol; 5 wt % dipropylene glycol; 30 wt % calcium carbonate (50=4.9 m, and 90=25 m).

[0084] Resin:curing agent mixing ratio: 100:100 parts by weight

[0085] Filler content in the mixture: 15 wt %

Example 4 (Comparative Example)

[0086] Resin base:

[0087] NCO-terminated MDI prepolymer with an NCO content of 10 to 15 wt %.

[0088] Curing agent: 80 wt % trifunctional polypropylene glycol (PPG) with Mw=1000 g/mol; 10 wt % trifunctional PPG with Mw=450 g/mol; 10 wt % dipropylene glycol;

[0089] Resin:curing agent mixing ratio: 100:50 parts by weight

[0090] Filler content in the mixture: 0 wt %

[0091] Composite Film:

[0092] The composite films are produced with the aid of a Super Combi 2000 laminating device. Then, 2 g/m.sup.2 of the adhesive composition is applied to the film (OPA or metOPP) to be adhered, and this film is then laminated under pressure onto the second film (PE or OPP). The acting roller pressure of the laminating work corresponds to a force of up to 200 N (20 kg).

[0093] Bonding Adhesion:

[0094] The bonding adhesion is determined in accordance with the standard DIN 53357 after 14 days of curing at room temperature, by means of a tensile testing machine from Instron (Instron 4301). For this purpose, sample strips of the composite film (sample width of 15 mm) were loaded between clamping jaws and then pulled apart at a pull-apart speed of 100 m/min, a pull-apart angle of 90, and a pull-apart length of 5 to 10 cm. The mean value of a determination in triplicate of the maximum force to be applied is indicated in relation to the sample width of 15 mm.

[0095] Elongation at Tear and Tearing Tension:

[0096] The elongation at tear and the tearing tension are determined according to the standard DIN 53504 (S2).

[0097] Primary Aromatic Amine (PAA) Content:

[0098] The wait time after the films are bonded until the adhesive is considered essentially migration-free is indicated. This is then the case when the primary aromatic amine (PAA) content is lower than 1.0 g/100 mL filling. 3% acetic acid is used as filling or filling simulator. An OPA/PE laminate produced by means of the adhesive, which surrounds the filling due to heat sealing, is used as packaging, wherein the PE side forms the inner side of the packaging and the inner side of the sealing seam. The primary aromatic amine content is determined according to 64 of the German Code on foodstuffs, consumer items and animal feed (Lebensmittel-, Bedarfsgegenstnde- and Futtermittelgesetzbuch, LFGB) according to method L 00.006.

[0099] Composite Materials:

[0100] OPA: oriented polyamide

[0101] PE: Polyethylene

[0102] OPP: oriented polypropylene

[0103] metOPP: metallized OPP (OPP coated with aluminum)

TABLE-US-00001 TABLE 1 Example 1 Example 2 (according to (according to Example 3 Example 4 the present the present (Comparative (Comparative invention) invention) example) example) Bonding 4.1 5.0 not 5.0 adhesion at measurable; N/15 mm on no laminates OPA/PE can be produced Bonding 1.4 1.8 not 1.8 adhesion at measurable; N/15 mm no laminates on OPP/ can be metOPP produced Tearing tension 8.5 12.0 5.5 in MPa Elongation at 400 350 400 tear in % PAA content 6 days 6 days 8 days <1.0 g/ 100 mL Sedimentation/ none none intense phase separation Abrasiveness low low high on laminating rollers