Presentation is loading. Please wait.

Presentation is loading. Please wait.

Atrak Pulp & Paper Industries Ltd.

Similar presentations

Presentation on theme: "Atrak Pulp & Paper Industries Ltd."— Presentation transcript:

1 Atrak Pulp & Paper Industries Ltd.
Paper & Board Coating

2 Why is Paper Coated ?? Cellulose Fiber Size : Soft Wood : Length 3 ~ 4 mm Diameter 25 ~ 50 Micron Hard Wood : Length 0.8 ~ 1.5 mm Diameter 10 ~ 35 Micron Pores between Fibers : 10 ~ 100 Micron. Printing Dot Diameter : 25 ~ 50 Micron. Coating the paper surface with Fine Pigments (Diameter 1~2 Micron) to cover the fibers and fill the pores.

3 Why is Paper Coated ?? Printability Smoothness Uniformity
Ink Receptivity Visual Properties Brightness Opacity Gloss Functionality Reduce Ink Consumption Glueability

4 A Binder is used to adhere the pigment to the fibers.
Coatings Purposes The whole purpose of a coating is to attach uniform layer of pigment to the base sheet. A Binder is used to adhere the pigment to the fibers. There are additional additives in the coating formula to help in processing or enhance final sheet properties.

5 Photo of Un-coated Paper
Magnification 200x

6 Photo of Coated Paper Magnification 2000x

7 Cross Section of Coated Paper
Magnification 2000x

8 Coating Ingredients Natural Pigment: Clay, Calcium Carbonate, Talc.
Synthetic Pigment: PCC, Plastic Pigment, TiO2, Silica, Satin White. Synthetic Binder: Latex. Hydrosolubles Binder: Starch, CMC, PVA, Casein. Additives: Dispersant, Thickener, Cross Linker, OBA, Lubricant, De-Foamer, etc. Water.

9 Coating Ingredients, Dry Weight %

10 Function of Coating Ingredients
Pigment : Govern optical & printing properties of the paper. Binders : Give the cohesion of the coating & adhesion of pigments to the base paper without affecting the properties brought by pigments. Dispersant : To disperse the pigments. Cross Linker : Provide wet pick resistant. OBA : To increase brightness. Lubricant : Improves flow properties, prevent coating adhesion on to calendar. Thickener : Modifies the rheology and/or the water retention of the colour. De-Foamer : Reduces foam.

11 Pigments Clay Interest : paper & ink gloss, rotogravure printability, stiffness. Draw back : lack of brightness, closed coating. GCC Interest : brightness, low viscosity, high solid, ink porosity. Draw back : gloss, low water retention, fiber coverage. TiO2 Interest : opacity, brightness, whiteness Draw back : cost, latex demanding.

12 Plastic Pigment PCC Silica
Pigments Plastic Pigment Interest : high gloss, brightness, low specific gravity. Draw back : price, more latex demand. PCC Interest : brightness, viscosity, low abrasivity. Draw back : cost, more latex demand. Silica Interest : brightness, high specific area, opacity. Draw back : cost, need higher cohesion binder.

13 Pigments Talc Satin White
Interest : smoothness, non abrasive, best for gravure. Draw back : gloss. Satin White Interest : high gloss. Draw back : work ability.

14 Pigment Structure Magnification 5000x

15 Pigments Properties Brightness : 84 ~ 96 % ISO
Particle Size Distribution : 0.22 ~ 2.00 Micron Surface Area : Fine Clay 20 ~ 25 m2/gram Standard Clay 18 ~ 20 m2/gram Calcined Clay 13 ~ 17 m2/gram GCC ~ 13 m2/gram

16 Pigments Properties Refractive Index :
Interface Substrate Angle I Angle R Light Comes Light Refracted R.I. is amount of lights refracted by the pigments. High R.I. = High Opacity.

17 Pigments Properties Pigments Composition Particle Size Shape R.I.
Brightness Clay Al2O3.2SiO2.2H2O 0.3 ~ 5.0 Hexagonal Platy 1.56 80 ~ 90 GCC CaCO3.MgCO3 0.7 ~ 2.0 Cubic Prismatic Platy 1.65 87 ~ 97 Talc MgO.4SiO2.H2O Platy 1.57 85 ~ 90 Gypsum CaSO4.2H2O 0.2 ~ 2.0 Roundish 1.52 92 ~ 94 Titanium TiO2 0.2 ~ 0.5 Rod Like 2.55 98 ~ 99 2.70 97 ~ 98 PCC CaCO3 0.1 ~ 1.0 Variable Rod Like 1.59 96 ~ 99 Calcined C. Al2O3.2SiO2 0.7 Aggregated Platy 93

18 Binders Latex Hard Latex : Higher gloss, low binding power, mainly for top coat. Web Offset Latex : Blistering resistance, low binding power. Soft Latex : Lower cost, high binding power, best for pre coat. Starch Interest : Stiffness, price. Draw Back : Mottling, low binding power, rheology at high speed.

19 Binders CMC PVA Protein
Interest : Water retention, rheology, binding power. Draw Back : Handling. PVA Interest : Excellent binding power, gloss, brightness. Draw Back : Price, rheology at high level. Protein Interest : Water retention, binding power, bulkier coating layer. Draw Back : Handling, rheology at high level, microbiology control.

20 What Does Binder Do ? To hold the pigments on the base paper.
To help give good printability. To give special characteristic. Pigment Binder

21 Latex Structure Latex Particles Pigments Particles

22 Styrene Butadiene Acrylic. Vinyl Acetate.
Main Binder Types Styrene Butadiene. Styrene Acrylic. Styrene Butadiene Acrylic. Vinyl Acetate.

23 Dry and Wet Pick Strength. Sheet and Ink Gloss. Printability.
The Influence of Binder Dry and Wet Pick Strength. Sheet and Ink Gloss. Printability. Blister Resistance. Ink Drying. Yellowing.

24 The Influence of Binder
Sheet Gloss Ink Gloss Pigment Coat Weight Binder Solid Content

25 Rheology Modifier (Thickener)
Increase low shear viscosity to allow proper application. Adjust high shear viscosity to provide coat weight control and run-ability. Increase water retention. Can enhance optical and printing properties of the finished sheet.

26 Rheology Modifiers Starch Protein Poly - Acrylates  Alco Gum
Sodium Alginate Urethane Modified Acrylates  Poly Phobe Cellulosic  Carboxyl Methyl Cellulose (CMC), Hydroxyl Ethyl Cellulose (HEC)

27 Atrak Pulp & Paper Industries Ltd.

Download ppt "Atrak Pulp & Paper Industries Ltd."

Similar presentations

Ads by Google