Alkali-Free vs Traditional Starch Adhesive: Which Is Right for Your Corrugator?

Starch-based adhesives have been the standard for corrugated board production since the 1950s. Traditional formulas use caustic soda (sodium hydroxide) to lower the gelatinization temperature. Modern alkali-free formulations achieve similar results through different chemistry. Which is better for your operation?

Understanding Traditional Starch Adhesive:

How It Works:

Traditional Stein-Hall adhesives use a two-part system:

• Carrier starch: Pre-cooked starch that holds raw starch in suspension

• Raw starch: Gelatinizes when heated, forming the bond

• Caustic soda: Lowers gel temperature from ~70°C to ~58-62°C

• Borax: Increases tack and viscosity

Advantages of Traditional Formula:

• Well-understood technology

• Lower raw material cost

• Predictable performance

• Wide compatibility with papers

Disadvantages:

• Caustic soda is hazardous (burns, eye damage)

• Equipment corrosion over time

• Handling and storage safety requirements

• Environmental concerns with wastewater

Understanding Alkali-Free Adhesive:

How It Works:

Alkali-free formulations use alternative chemistry to achieve low gel temperatures without caustic soda:

• Modified starch chemistry

• Alternative pH modifiers

• Proprietary additives for tack and penetration

Advantages of Alkali-Free:

• Safer handling (no caustic burns)

• Reduced equipment corrosion

• Easier wastewater treatment

• Better storage stability

• No caustic soda purchase/storage

• Simplified safety training

Disadvantages:

• Higher product cost per kg

• May require process adjustments

• Some formulas less tolerant of paper variability

Performance Comparison:

| Factor | Traditional | Alkali-Free |

| Bond Strength | Excellent | Excellent |

| Setting Speed | Good | Good to Excellent |

| Water Resistance | Standard | Standard to Better |

| Storage Stability | 6-12 months | 12-18 months |

| Viscosity Stability | Good | Better |

| Paper Compatibility | Excellent | Very Good |

Cost Analysis:

Traditional Adhesive Costs:

• Starch: $0.30-0.50/kg

• Caustic soda: $0.20-0.30/kg (5-8% of formula)

• Borax: $0.15-0.25/kg (2-3% of formula)

• Total prepared cost: ~$0.08-0.12/kg

Alkali-Free Adhesive Costs:

• Alkali-free powder: $0.40-0.60/kg

• Preparation: Just add water

• Total prepared cost: ~$0.10-0.15/kg

Hidden Cost Savings with Alkali-Free:

• Reduced equipment maintenance (less corrosion)

• Lower safety/PPE costs

• Simpler wastewater treatment

• Reduced liability risk

• Less storage space needed

When to Choose Which:

Choose Traditional If:

• Maximum cost sensitivity

• Experienced operators comfortable with caustic

• Good safety systems already in place

• Standard paper grades only

Choose Alkali-Free If:

• Worker safety is priority

• Exporting to markets with strict chemical regulations

• Reducing maintenance costs

• Simplifying operations

• Using sensitive or coated papers

Xuegong offers both traditional and alkali-free adhesive options. Our alkali-free series provides the safety and convenience benefits while matching traditional adhesive performance.