Extenders for use in synthetic resin adhesives (Urea-Formaldehyde) for plywood - Code of practice

IS 15684 - Scope Summary

IS 15684 specifies quality and testing requirements for extenders used in adhesive resin mixes, ensuring proper bonding in veneer applications.

Key Points:

• Scope: Covers extenders meeting purchaser-specified tests per IS 1508.
• Acidity (Clause 5.6):
  • Acidity = volume (ml) of 0.1 N NaOH used per gram of moisture & fat-free extender.
  • Controls adhesive pH to avoid pre-curing and bonding failure.
• Mixing Method (Clause 6):
  1. Mix extenders with part resin → paste.
  2. Add remaining resin → smooth mix.
  3. For protein extenders, add liquid ammonia to uncoil proteins.
  4. Powder resin: use part water for extender paste, then add rest water + resin.

Acidity Formula:

[ \text{Acidity} = \frac{\text{ml of 0.1 N NaOH consumed}}{\text{1 g moisture & fat free extender}} ]

Reference:

• Extender quality tests as per IS 1508.
• Resin-extender mixing sequence critical for performance.

flowchart LR
    A[Extender] --> B[Mix with part resin]
    B --> C[Paste formed]
    C --> D[Add remaining resin]
    D --> E[Smooth resin mix]
    E --> F[Add other ingredients]

This ensures uniform dispersion and avoids lumps, critical for adhesive strength.

IS 15684 References - Key Points & Specifications

• Referenced Standards:

  • Extender quality tests per IS 1508.
  • ICS Codes relevant: 79.060.10 (Adhesives), 83.040.30 (Wood-based panels), 83.180 (Veneers).

• Acidity (Clause 5.6):

  • Acidity = ml of 0.1 N NaOH used per gram of moisture & fat-free extender.
  • High acidity → pre-curing risk → poor bonding.
  • Maintain pH of adhesive mix by corrective measures.

• Mixing Method (Clause 6):

  1. Mix extenders with part resin → paste.
  2. Add remaining resin → smooth mix.
  3. For protein extenders, add liquid ammonia to uncoil protein.
  4. For powder resin, use part water to make extender paste, then add rest water & resin.

• Amendments & Contact:

  • Check latest amendments for updates.
  • BIS offices and contacts listed for standards and clarifications.

Quick Formula Summary:

flowchart LR
    A[Extender] --> B[Mix with part resin]
    B --> C[Paste formed]
    C --> D[Add remaining resin]
    D --> E[Smooth adhesive mix]
    subgraph Protein Extenders
        C --> F[Add liquid ammonia]
        F --> D
    end

For detailed test methods, refer to IS 1508. Always verify with the latest BIS publications.

IS 15684: General Requirements Summary

Key Specifications:

• Extenders Quality: Must meet tests per IS 1508 as specified by purchaser (Clause 5.0).
• Acidity of Extender (Clause 5.6):
  • Defined as ml of 0.1 N NaOH used per gram of moisture & fat-free material.
  • High acidity → pre-curing risk → poor bonding.
  • Maintain final adhesive pH by corrective measures.

Method of Mixing (Clause 6):

1. Mix extenders with part of resin → paste-like mix.
2. Avoid adding all resin at once to prevent lumps.
3. For protein extenders, add small % liquid ammonia to uncoil protein.
4. Add remaining resin, stir to smooth viscosity.
5. Add other ingredients as required.
6. For powder resin, use part water for extender paste, then add rest water & resin.

Acidity Calculation Formula:

[ \text{Acidity} = \frac{\text{Volume of 0.1 N NaOH (ml)}}{\text{Weight of moisture & fat-free sample (g)}} ]

Mixing Process Flow:

flowchart TD
  A[Start: Extender] --> B[Mix with part resin]
  B --> C{Proteineous Extender?}
  C -- Yes --> D[Add liquid ammonia]
  C -- No --> E[Add remaining resin]
  D --> E
  E --> F[Stir to smooth mix]
  F --> G[Add other ingredients]
  G --> H[Final adhesive mix ready]

Note: Always refer to latest IS 1508 for test methods and BIS updates for revisions.

IS 15684: Classification & Specifications of Extenders

1. Classification of Extenders (Clause 4)

• Protein-based Extenders: Derived from proteinous materials.
• Amylaceous (Starch-based) Extenders: Contain 90–95% starch; swell and increase resin volume, enhancing adhesive properties.
  • Examples: Tamarind seed powder, tapioca starch, maida, wheat flour.

2. Quality Requirements (Clause 5.6)

• Acidity of Extenders:
  • Measured by titration with 0.1 N NaOH.
  • Acidity = ml of 0.1 N NaOH per gram of moisture & fat-free extender.
  • High acidity → may cause premature curing → poor bonding.

3. Mixing Method (Clause 6)

• Mix extenders with part of resin to form paste → prevents lumps.
• For protein extenders, add small % liquid ammonia to uncoil protein.
• Add remaining resin and stir for smooth adhesive mix.
• For powder resin, use part of water to make extender paste before adding resin and remaining water.

Key Formula for Acidity:

[ \text{Acidity} = \frac{\text{Volume of 0.1 N NaOH (ml)}}{\text{Weight of extender (g)}} ]

Summary Table: Extender Types

flowchart LR
    A[Extenders] --> B[Protein-based]
    A --> C[Amylaceous (Starch-based)]
    C --> D[Tamarind seed powder]
    C --> E[Tapioca starch]
    C --> F[Maida, Wheat flour]
    B --> G[Require ammonia treatment]

Note: Extenders must be free from insects, mould, and fungus (Clause 3.3) to maintain quality.

IS 15684: Requirements for Quality - Key Points

1. Quality Tests (Clause 5.0):

   • Extenders must pass tests as per purchaser's requirements.
   • Testing follows IS 1508 methods.

2. Acidity (Clause 5.6):

   • Acidity = ml of 0.1 N NaOH per gram of moisture & fat-free material.
   • High acidity affects adhesive pH → risk of pre-curing and poor bonding.
   • Corrective measures needed to maintain final adhesive pH.

3. Mixing Method (Clause 6):

   • Mix extenders with part resin → paste.
   • Add rest of resin gradually for smooth mix.
   • For protein extenders, add liquid ammonia to uncoil protein.
   • For powder resin, use part water for extender paste, then add rest water & resin.

Acidity Calculation Formula

[ \text{Acidity} = \frac{\text{Volume of 0.1 N NaOH (ml)}}{\text{Mass of sample (g)}} ]

Summary Table: Extender Quality Checks

flowchart TD
    A[Extender Sample] --> B[Test as per IS 1508]
    B --> C{Pass?}
    C -- Yes --> D[Measure Acidity]
    C -- No --> E[Reject Extender]
    D --> F{Acidity High?}
    F -- Yes --> G[Correct pH of Adhesive Mix]
    F -- No --> H[Proceed with Mixing]
    H --> I[Mix Extender + Part Resin → Paste]
    I --> J[Add Remaining Resin Gradually]
    J --> K[Add Other Ingredients]
    K --> L[Final Adhesive Mix Ready]

Note: Always refer to the latest edition of IS 15684 and IS 1508 for updated test methods and limits.

IS 15684 - Clause 6: Method of Mixing Extenders with Resin

Key Specifications & Steps:

• Step 1: Mix extenders with part of the resin to form a paste-like mix.
  • Avoid adding the entire resin at once to prevent powder floating and lump formation.
• Proteineous Extenders:
  • Add a small percentage of liquid ammonia to extract and uncoil protein for better dispersion.
• Step 2: Add the balance resin to the paste and stir thoroughly to get a smooth resin mix with required viscosity.
• Step 3: Add other ingredients as needed.

For Powder Resin:

• Use part of the water for making extender paste.
• Then add remaining water and powder resin to complete the mix.

Important Notes:

• Mixing time for protein extraction: 15 to 20 minutes.
• Extender powder must pass through IS sieve No. 100 for fineness.
• Proper mixing ensures uniform adhesive spread, prevents pre-curing, and avoids poor bonding or blisters.

Summary Table:

flowchart TD
    A[Extender] --> B[Mix with part resin]
    B --> C{Proteineous extender?}
    C -- Yes --> D[Add liquid ammonia, mix 15-20 min]
    C -- No --> E[Proceed]
    D --> E
    E --> F[Add remaining resin, stir thoroughly]
    F --> G[Add other ingredients]
    G --> H[Final adhesive mix]

This method ensures uniform dispersion, correct viscosity, and optimal bonding per IS 15684.

IS 15684: Testing and Inspection Key Points

• Reference Standard: Testing of extenders shall follow IS 1508 methods (Clause 5.0).

• Acidity Test (Clause 5.6):

  • Acidity is measured as the volume (ml) of 0.1 N NaOH required to neutralize 1 g of moisture-free, fat-free extender.
  • High acidity affects adhesive pH, risking premature curing and poor bonding.

• Mixing Method (Clause 6):

  1. Mix extenders with part resin to form a paste (avoid lumps).
  2. For protein extenders, add liquid ammonia to uncoil proteins.
  3. Add remaining resin and stir for smooth viscosity.
  4. Add other ingredients as needed.
  5. For powder resin, mix extender with part water first, then add resin and remaining water.

Acidity Calculation Formula

[ \text{Acidity} = \frac{\text{Volume of 0.1 N NaOH (ml)}}{\text{Weight of sample (g)}} ]

Summary Table: Acidity Test

flowchart TD
    A[Extender Sample] --> B[Remove moisture & fat]
    B --> C[Titrate with 0.1 N NaOH]
    C --> D[Measure volume (ml) used]
    D --> E[Calculate acidity (ml/g)]
    E --> F{Is acidity high?}
    F -- Yes --> G[Adjust adhesive pH]
    F -- No --> H[Proceed with mixing]

Note: Always refer to the latest editions of IS 1508 and IS 15684 for updated test methods and quality criteria.

IS 15684: Packaging and Storage - Key Specifications & Formulas

1. Acidity of Extender (Clause 5.6)

• Definition: Acidity = volume (ml) of 0.1 N NaOH used per gram of moisture-free, fat-free extender.
• Significance: Higher acidity → lower pH → risk of premature adhesive curing → poor bonding.
• Action: Correct acidity to maintain final adhesive mix pH.

2. Moisture Content (Clause 5.2)

• Recommended moisture content of extenders: 12% to 14%
• Excess moisture → fungal/mould growth → deterioration.

3. Method of Mixing (Clause 6)

• Mix extenders with part of resin → paste.
• Avoid adding all resin at once to prevent lumps.
• For protein extenders, add liquid ammonia to uncoil proteins.
• Add remaining resin and stir to get smooth mix.
• For powdered resin, use part water to make extender paste first.

Summary Table: Extender Quality Parameters

flowchart LR
    A[Extender] --> B[Mix with part resin]
    B --> C[Paste-like mix]
    C --> D[Add remaining resin]
    D --> E[Add additives]
    E --> F[Final adhesive mix]

Note: Store extenders in dry, cool conditions to maintain moisture and acidity levels.

IS 15684: Safety and Handling - Key Points & Formulas

1. Acidity of Extenders (Clause 5.6):

• Definition: Acidity = volume (ml) of 0.1 N NaOH used per gram of moisture-free, fat-free extender.
• Importance: High acidity can cause premature adhesive curing → poor bonding.
• Action: Adjust pH of adhesive mix accordingly.

2. Mixing Method (Clause 6):

• Mix extenders with part resin → paste-like consistency.
• Avoid adding all resin at once to prevent lumps.
• For protein extenders, add small % liquid ammonia to uncoil protein.
• Add remaining resin and stir to desired viscosity.
• For powder resin, use part water to make extender paste, then add remaining water + resin.

Summary Table for Acidity Measurement

Handling Tips:

• Follow mixing sequence strictly for best adhesive performance.
• Monitor acidity and pH to avoid premature curing.
• Use ammonia cautiously with protein extenders.

flowchart TD
    A[Extender] --> B[Mix with part resin]
    B --> C[Paste-like mix]
    C --> D[Add remaining resin + stir]
    D --> E[Add other ingredients]
    E --> F[Final adhesive mix]

Note: Refer to IS 15684 for detailed chemical safety and handling procedures.

IS 15684 Annexes and Appendices: Key Points

The provided context from IS 15684 does not explicitly list annexes or appendices with formulas or tables. However, based on the standard's scope (extenders for plywood adhesives), key relevant info includes:

Key Specifications & Tables (from Clause 5.6)

• Acidity of Extender:
  • Measured by titration with 0.1 N NaOH (ml per gram of moisture-free, fat-free material).
  • Higher acidity → risk of premature adhesive curing → poor bonding.

Mixing Method (Clause 6)

• Mix extenders with part resin → paste → add remaining resin → smooth mix.
• For proteinous extenders, add small % liquid ammonia to uncoil protein.
• Powder resin requires partial water for paste, then add remaining water and resin.

Typical Table Format for Acidity (Example):

Summary Diagram: Mixing Procedure

flowchart TD
    A[Extender Powder] --> B[Mix with part Resin]
    B --> C[Form Paste]
    C --> D[Add remaining Resin]
    D --> E[Stir to smooth mix]
    E --> F[Add other ingredients]

Note: For detailed annexes, formulas, or tables, refer to the full IS 15684 document or related BIS publications. This standard references other IS codes for related test methods and specifications.