Clay coated paper surface

Figure 4. Photomicrograph (7200X) of 28 clay coated paper surface. Longer of two lines represents lp.

Water-Based Primer/Adhesive for Extrusions end Laminations to Clay Coated Paper Surfaces... 

Polaqua W7 is an excellent extrusion, lamination and printing primer for use on a wide variety of accepting substrates and in particular clay coated paper surfaces. 

In the quest for the ideal adhesive system to suit an application needs, it is essential to understand the effect of the silicone properties on the mechanisms of Silicone adhesion. The primary requirement for good adhesion is the creation of an intimate interface through Wetting and spreading of the silicone onto the substrate. The low surface tension and viscosity range of silicones satisfy this necessary condition. Therefore, the mechanical mechanism of adhesion is operative and plays a key role in adhesion of silicones to many different substrates such as leather, textile fabrics, porous metals like anodized aluminium, porous plastic and composite materials, and specialty papers like glassine, super calendered kraft and clay-coated papers. 

A process for upgrading kaohu by grinding in a stirred bead miU has been reported (Stanczyk and Feld, U.S. Bur Mines Rep. Invest. 6327 and 6694, 1965). By this means the clay particles are delaminated, and the resulting platelets give a much improved surface on coated paper. 

Figure 6.9 Irregular deposit and corrosion-product mounds containing concentrations of sulfate-reducing bacteria on the internal surface of a 316 stainless steel transfer line carrying a starch-clay mixture used to coat paper material. Attack only occurred along incompletely closed weld seams, with many perforations. Note the heat tint, partially obscured by the deposit mounds, along the circumferential weld.

Amorphous silica has become increasingly important in paper technology. It cannot be used alone because it affects coating rheology and adhesive demand. But used in combinations with other fillers, it improves the brightness, opacity, and ink receptivity of paper. Similarly, talc is used as a 10 to 40% replacement for other fillers to improve paper surface smoothness and ink receptivity. Talc is also used in place of clay if clay is not locally available. 

Figure 4.42 shows a cross-section of a PVC foam gasket. The gasket (30) comprises a release liner (40) comprising release paper (42) having a release (preferably silicone) coating (38) which provides a release surface. This release liner (40) has an upper surface which is a release surface. The release paper is about 78 lb., clay-coated, long-fiber, super-calendered, flat, heat-resistant paper. Plastic or polymeric film may be substituted for the paper layer (42). A layer of pressure sensitive adhesive (36) is applied to the release surface of the silicone... 

Applying Polaqua W7 on a clay coated surface will allow for extremely high bond strengths from heat sealing of LDPE to the surface or for extrusions of LDPE to the clay surface. This makes Polaqua W7 suitable for priming clay coated boards for back sealing improvement in cup and box applications. In addition, Polaqua W7 will improve the bond of the clay to the paper surface. 

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