Delivering Value through People Chemistry Activated Filler Increasing Filler Levels Asian Paper April

Delivering Value through People Chemistry Issues associated with increased filler content -decrease in number of fibres in the sheet which reduces the number of fibre-fibre bonds -reduced area of contact between the fibres. -increasing the furnish surface area reduces the efficiency of wet end chemicals such as sizing agents and strength agents AREA OF CONCERNEFFECT OF INCREASING FILLER CONTENT Wet endWet web strength reduced RetentionFPR reduced DrainageIncreases drainage rate FormationCan be beneficial or detrimental Chemical demandMay increase due to larger surface area ClothingDramatically increases wire abrasion, felt filling. Dry end surface strengthIncreases dusting and fluffing due to the reduction in surface pick strength PAPER PROPERTIES StrengthTensile and burst reduced BulkDecreases StiffnessDecreases Two sidednessIncreases difference 2

Delivering Value through People Chemistry Cobb vs. Calcium Carbonate Surface Area at 15% Filler Loading Increased surface area reduces the efficiency of adsorbed wet end chemicals Applications of Wet-End Paper Chemistry Au and Thorn (Eds.). Blackie Academic, Glasgow, 1995 Chemical Efficiency 3

Delivering Value through People Chemistry 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0%5%10%15%20%25%30%35% Filler Loading % of Original Burst There exists a strong negative relationship between filler content and paper strength. Dispersed Clay Loading & Strength The Hylode System For Fibre Replacement R.D. Mather PIRA Papermakers Conference,

Delivering Value through People Chemistry Bonding Disruption Untreated filler FillerAir gap Fibre-fibre bonds are relaced by weaker fibre-filler bonds over the area of contact. Additional void volume created Reduced bonding area 5

Delivering Value through People Chemistry %10%20%30%40%50%60% Filler Content (%) Tensile Index (Nm/g) 100 kg/t starch 50 kg/t starch 10 kg/t starch No starch Strength agents (including starch) added to recover strength have a reducing effect Dry Strength Additives 6

Delivering Value through People Chemistry Starch-Filler Composites Filler coated with bonding material FillerBonding material Bonding material improves filler- fibre bonding Void may be filled or partially filled. Overall bonding levels increased but with a loss of opacity 7

Delivering Value through People Chemistry Pre-flocculation Reduced fibre-fibre contact area: - low paper strength Larger fibre-fibre contact area: - higher paper strength Benefits -Less interference with inter-fibre bonding -Lower internal surface area -Easier retention 8

Delivering Value through People Chemistry 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0%5%10%15%20%25%30%35% Filler Loading % of Original Burst There exists a strong negative relationship between filler content and paper strength. Pre-flocculation reduces strength loss Dispersed Clay Pre-flocculated Clay Strength Benefit The Hylode System For Fibre Replacement R.D. Mather PIRA Papermakers Conference,

Delivering Value through People Chemistry Light Scattering %5%10%15%20% Pigment content, % on fibre Light-scattering coef. Dispersed filler Preflocced filler Light scattering is due to reflection and refraction at air/cellulose or air-filler interfaces. Increasing filler content increases light scattering. With less surface coverage of the fibre, filler pre-flocculation will reduce the scattering efficiency of the pigment, resulting in lower opacity. Optimization of Pigment Performance in Paper B.Alince Fundamentals of Papermaking, Trans. 9th Fund. Res. Symp., Cambridge,

Delivering Value through People Chemistry Strength vs Light Scattering ,0001,200 Light-scattering coefficient Tensile index, Nm/g Dispersed filler Preflocced filler Disruption of inter-fibre bonding will reduce strength and increase light scattering -there is an inverse relationship between strength and opacity The exact same relationship holds for preflocculated filler -this confirms that the principle effect is preservation of inter-fibre bonds The tensile/opacity relationship is maintained, ‘though at a higher sheet filler content 11

Delivering Value through People Chemistry Reported Benefits A series of benefits are reported for pre-flocculated filler, including internal bonding is maintained / enhanced energy savings in refining equivalent strength and opacity achieved at higher filler contents filler retention, formation and drainage are improved better press dewatering energy savings in drying improved wet web strength 12

Delivering Value through People Chemistry Single Polymer Low molecular weight polymers produce patching and charge neutralisation as the dominant floc types. The flocs tend to be relatively weak and break down under the shear forces of a modern paper machine. High molecular weight linear polymers produce bridging flocculation. Poor mixing of viscous flocculent with pigment slurry results in a broad floc size distribution, often worse at higher filler solids levels. High shear mixing is needed to generate a regular floc-size distribution. When adding a single ionic agent the charge balance of the treated system is determined by the added charge. Overall charge balance will limit the optimum treatment. 13

Delivering Value through People Chemistry Dual Polymer Typical process addition of a flocculating agent to a filler dispersion shearing of the dispersion addition of a second flocculating agent further shearing of the resultant flocs to the desired particle size. Dual polymer systems produce flocs with better shear stability and a narrower particle size distribution than flocs from single polymer systems. Microparticles may also be included in the process 14

Delivering Value through People Chemistry Pre-floc Limitations System charge balance concerns Filler-fibre bonding and filler-filler bonding remain weak Preflocculated filler allows a limited filler increase of a few % points. fibre-fibre bonding filler-filler bonding fibre-filler bonding These weak bonds must be addressed 15

Delivering Value through People Chemistry Bonding Failure the mode of failure in MD tensile is mainly the shearing of inter-fibre bonds. Z-direction tensile failure is adhesive failure (between two elements) or cohesive failure (within an element, layer or film). CD tensile is a combination of these two failure modes. Filler-filler bonding is an obvious area of weakness. Polymers used to pre-flocculate fillers are often present in too low a concentration to generate significant inter-particle bonding. 16

Delivering Value through People Chemistry Developments Use of AmiForm™ micropolymer to generate a pre-floc, the micropolymer also functions as a bonding agent in the flocculated filler Both filler-filler and filler-fibre bonding are enhanced The amphoteric micropolymer contributes no net charge to the wet end. Charge balance is maintained at all addition levels No quenching of OBAs The pre-floc may be encapsulated by starch or other dry strength agents to further increase fibre-filler bonding 17

Delivering Value through People Chemistry AmiForm™ Addition 0 kg/tf AmiForm 2 kg/tf AmiForm 3 kg/tf AmiForm 5 kg/tf AmiForm Effect of micropolymer on GCC particle flocculation. - addition rate is given as kilograms per tonne dry filler 18

Delivering Value through People Chemistry Case Study #1 Description Asia, 950 t/d. Gapformer Plain Paper Copier, 80 gsm Results Reduced white water turbidity Sheet ash rises from 22.7% to 23.8% Filler addition reduced by 2% Steady improvement in formation index 19

Delivering Value through People Chemistry Case Study #2 Description Asia, 900 t/d. Gapformer Plain Paper Copier, 70 gsm Results Reduced white water turbidity FPR increased 2% Filler addition reduced by 4% Filler content increased Drainage improved RemarkBefore TrialDuring Trial Time06: : Dosage AmiForm 528 (kg/t CaCO 3 )05 Particle Size (µm) W/W Turbidity (NTU) Machine Speed (m/min) Drainage Time (sec/500 ml)3129 FPR (%)7476 FPAR (%)4447 Filler Addition (l/min)7572 Filler Content (%)

Delivering Value through People Chemistry Conclusions Filler pre-treatment is receiving much renewed interest Encapsulation and pre-flocculation are gaining most attention Floc size and floc tenacity are important for pre-flocculated fillers Poor filler-to-filler bonding is a potential weak point with pre- flocculated fillers AmiForm ™ Activated Filler addresses the issues of floc size, floc tenacity and filler-filler bonding Further Developments: Encapsulated Pre-floc –but that is a topic for a future presentation. 21

Delivering Value through People Chemistry Thank You Any Questions? 22

Delivering Value through People Chemistry Filler Location Expansion: Fillers expands the fibre network and thus lowers its density. Expansion of the fibre network improves the light scattering properties of the paper. Filler particles interfere with the fibre-fibre bonding, lowering mechanical strength Void Filling: Fillers locates in the voids between the fibres No interference with fibre-fibre interactions, mechanical properties not affected but light scattering will increase. No volume expansion of the fibre network, the density of the paper is increased. Insertion: Filler inserts between the fibres but does not result in full separation Inter-fibre contact area is reduced, lowering the mechanical properties. Insertion of filler will not affect the overall light scattering if there are no additional voids formed. Ref. Eklund et al 23