Composite thermoplastic laminate
A composite sheet material includes a cover sheet, a substrate and an adhesion promoting layer. The cover sheet has a cover sheet material. The substrate has a substrate material. The adhesion promoting layer is disposed between the cover sheet and the substrate. A first side of the adhesion promoting layer disposed towards the cover sheet has an affinity to bond with the cover sheet material. A second side of the adhesion promoting layer disposed towards the substrate has an affinity to bond with the substrate material.
1. A method of making a composite sheet material, comprising:
providing a cover sheet having a cover sheet material, the cover sheet material including polyethylene terephthalate;
providing a substrate having a substrate material, the substrate material including polypropylene;
providing an adhesion promoting layer disposed between the cover sheet and the substrate;
performing a first formation process to combine the cover sheet, the substrate and the adhesion promoting layer, the first formation process including drawing polypropylene from the substrate and into the adhesion promoting layer.
2. The method of claim 1 , wherein the performing the first formation process includes applying a first temperature above room temperature and first pressure above atmospheric pressure for a first time period to the cover sheet and the substrate.
3. The method of claim 2 , further comprising allowing the laminate to cool down to a lower temperature after the applying the first temperature and first pressure.
4. The method of claim 3 , further comprising applying, after the allowing the laminate to cool down to the lower temperature, a second temperature above room temperature and second pressure above atmospheric pressure for a second time period to the laminate.
5. The method of claim 4 , wherein the applying the second temperature and second pressure for a second time period provides a larger amount of energy to the laminate than the applying the first temperature and first pressure for the first time period provides to the laminate.
6. The method of claim 5 , wherein at least one of the first temperature and second temperature is above a melting point of a thermoplastic material of the composite sheet material.
7. The method of claim 4 , wherein after the applying the second temperature, bonds between the cover sheet, the adhesion promoting layer and the substrate are primarily covalent bonds.
8. The method of claim 1 , wherein
a first side of the adhesion promoting layer disposed towards the cover sheet has an affinity to bond with the cover sheet material, and
a second side of the adhesion promoting layer disposed towards the substrate has an affinity to bond with the substrate material.
9. The method of claim 1 , wherein the adhesion promoting layer includes a material selected from the group consisting of ethyl vinyl acetate, ethylene methyl acrylate and oxazoline.
10. The method of claim 1 , further comprising providing a polyurethane adhesion promoting layer, wherein
the cover sheet is disposed between the polyurethane adhesion promoting layer and the substrate, or
the substrate is disposed between the polyurethane adhesion promoting layer and the cover sheet.
11. The method of claim 10 , wherein the polyurethane adhesion promoting layer includes a material selected from the group consisting of a urethane prepolymer and an acrylic polymer.
12. The method of claim 1 , wherein a bond between the adhesion promoting layer and the substrate is primarily a covalent bond.
13. The method of claim 1 , wherein the substrate material includes glass.
14. The method of claim 11 , wherein a bond between the adhesion promoting layer and the substrate is primarily a covalent bond.