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 MicronHard Wood : Length 0.8 ~ 1.5 mm Diameter 10 ~ 35 MicronPores 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 ReceptivityVisual PropertiesBrightnessOpacityGlossFunctionalityReduce Ink ConsumptionGlueability
4 A Binder is used to adhere the pigment to the fibers. Coatings PurposesThe 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.
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 basepaper 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 PigmentsClayInterest : paper & ink gloss, rotogravure printability, stiffness.Draw back : lack of brightness, closed coating.GCCInterest : brightness, low viscosity, high solid, ink porosity.Draw back : gloss, low water retention, fiber coverage.TiO2Interest : opacity, brightness, whitenessDraw back : cost, latex demanding.
12 Plastic Pigment PCC Silica PigmentsPlastic PigmentInterest : high gloss, brightness, low specific gravity.Draw back : price, more latex demand.PCCInterest : brightness, viscosity, low abrasivity.Draw back : cost, more latex demand.SilicaInterest : 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 WhiteInterest : high gloss.Draw back : work ability.
18 BindersLatexHard 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.StarchInterest : 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.PVAInterest : Excellent binding power, gloss, brightness.Draw Back : Price, rheology at high level.ProteinInterest : 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.PigmentBinder
23 Dry and Wet Pick Strength. Sheet and Ink Gloss. Printability. The Influence of BinderDry and Wet Pick Strength.Sheet and Ink Gloss.Printability.Blister Resistance.Ink Drying.Yellowing.
24 The Influence of Binder Sheet GlossInk GlossPigmentCoat WeightBinderSolid 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.