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Starch Adhesives for Automatic Corrugated Plants

B.V. Bhaskar Reddy

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OBJECTIVE

Discuss quality parameters of Starch Adhesives for Automatic Plants and how they can be achieved.

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Topics

• Is Starch Adhesive for Automatic Plants different !

• What is good Starch Adhesive ?• Is good Starch Adhesive critical for Board

making !• How to maintain / improve adhesive quality• Various adhesive preparation methods• New developments in Starch Adhesives• Suggestions

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Is Starch Adhesive for Automatic Plant different

Bonding process in 2 ply at single facer need to be completed before it enters Double Backer. Adhesive should aid in bringing moisture to 7.5% in 2 ply board.

Bonding formed at Single Facer should not weaken when wetted again at double backer with adhesive ( free water is available in starch suspension).

Single Facer bonding should withstand 130 -140 degrees temperature in double backer.

Glue applied at Double Backer should be able to set without any pressure and bonding process should be completed with in few minutes.

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What is good Starch Adhesive

An adhesive is considered to be good if it is able to give complete bonding at plant ‘s designed speed in the presence of adequate heating at Single Facer and Double Backer. To realise this , adhesive needs to have following properties

• Appropriate Viscosity (35 sec -80 sec in B4 cup). • High Initial Tack – ability to hold plys together initially• Solids in the range of 20 -33%• Consistency in batch to batch glue properties• Fast Setting

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Is good Starch Adhesive critical for Board making !

Good starch adhesive is essential for

Running higher GSM and high B/F paper For achieving complete bonding / fiber tear High speed machines ( above 100 Mtr / min) For better PAT values For trouble free plant operation

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Adhesive Preparation MethodsOne tank system – Starch , Borax and Caustic are added

in one tank to get uniform gelling.

Cost effective Inconsistency & erratic viscosity behavior Very early break down of adhesive

Two tank system – some portion of starch is cooked and added to starch Borax and caustic mix

Better than one tank system Will bring in initial stability in viscosity. Break down of viscosity may occur later.

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Adhesive Preparation Methods

Carrier based formulations- Carrier is added to starch , Borax and Caustic solution

Carriers are very expensive and in most cases imported.

Adhesive is stable.

Modified Starch based formulations – Various starch modifications are made at Adhesive manufacturing plants. These modified starches are mixed with water to get glue.

Relatively expensive. Gives stable and consistent adhesive with high initial

tack.

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How to maintain Adhesive Quality

• Use pure Starch with Stable viscosity.

• Procure Borax and Caustic from reputed manufacturer / importer

• Set up proper Glue Kitchen / High shear Mixer. Storage tank and circulation system is desirable

• Trained & permanent gum mixing personnel

• Else outsource adhesive according to needs

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New Developments

• Low Energy consuming adhesives. S/F and Double Backers can be run at low temperatures

• Environmental friendly Adhesives. Very low

usage of Borax & Caustic Soda.

• Specially gelatinized Starches. These glues are compatible with high speed ( 400 Mtr /min ) machines.

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Suggestions

• Association can engage Starch ( Maize) manufacturers to adhere to quality parameters.

• Outsource critical part of adhesives ( 30-35%) and continue to use raw starch (65-70%). This would bring in quality and consistency.

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