Method and apparatus for adhesive application to barrier sheet
According to one embodiment, a process for applying an adhesive material onto a barrier sheet substrate is provided. The process includes providing an adhesive material having viscosity of at least about 10,000 centipoise at 250° F. The adhesive material is applied to a multitude of cavities on a surface of a first tool with a coater unit in close proximity to the surface. The adhesive material is transferred from the surface of the first tool to the substrate supported on a surface of a second tool and pressed against the surface of the first tool.
1. A process for applying an adhesive material onto a sheet substrate comprising the steps of: a) providing an adhesive material having viscosity of at least about 10,000 centipoise at 250° F. as measured by Brookfield Rheometer (RVDVII+) using Spindle #29 at 2 rpm; b) applying said adhesive to a multitude of cavities formed on a surface of a first tool with a coater unit having at least one adhesive material applicator in close proximity to the surface; and c) transferring the adhesive material at a thickness of at least 2 mil from the surface of the first tool to said substrate supported on a surface of a second tool and pressed against the surface of the first tool.
2. The process of claim 1 wherein the first tool is a gravure roll.
3. The process of claim 2 wherein at least a plurality of the multitude of cavities have a depth of greater than 3 mils.
4. The process of claim 2 wherein said roll further provides embossing of said sheet substrate.
5. The process of claim 4 wherein said embossing identifies nail or fastener zones.
6. The process of claim 2 wherein at least 20% of a substrate contacting surface of the gravure roll is comprised of cavities.
7. The process of claim 1 wherein said adhesive comprises at least one additive selected from a liquid plasticizer, resin, and/or tackifier having a first Tg and a UV reactive acrylic polymer having a Tg higher than the first Tg.
8. The process of claim 7 wherein said additive comprises 5%-40% by weight of the adhesive.
9. The process of claim 1 wherein said adhesive material is deposited in a repeating pattern that does not cover an entire surface of the substrate.
10. The process of claim 9 further comprising the use of a separation blade, wherein the pattern is comprised of shapes having a longest straight edge that is not parallel to a longitudinal axis of the separation blade.
11. The process of claim 1 wherein said cavities have a depth of greater than at least 1.5 times a thickness of the adhesive as applied on the substrate.
12. The process of claim 1 wherein said cavities include at least one of a mechanism for pressurizing the cavity, an angled cell wall, a compound angle cell wall, a functional coating, or mixtures thereof.
13. The process of claim 1 wherein each of said multitude of cavities is defined by a wall and said wall has a temperature of greater than about 212° F.
14. The process of claim 1 further including, following step c), forming a roll of the substrate.
15. The process of claim 14 further comprising the application of a release coating having low affinity for said adhesive material.
16. The process of claim 14 further comprising the application of a release liner.
17. The process of claim 1 wherein said adhesive is deposited in a thickness of at least 3.0 mils.
18. The process of claim 1 wherein the adhesive material comprises a UV reactive acrylic polymer having a weight average molecular weight (mw) of at least 100,000 Daltons as measured by Gel Permeation Chromatography.