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        # From Powder to Pellet: PVC Granule Compounding for Footwear

        

**Topic:** Footwear

        

Your footwear buyer demands PVC granules with a Shore A of exactly 72 ± 2. Your last three batches ranged from 65 to 78. He's about to take his 100-tonne order to your competitor.

        
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## Problem

PVC granule compounding for footwear requires extremely tight tolerances on hardness, density, and melt flow index. The compound must process smoothly in injection molding machines while delivering consistent sole properties. Common problems include: hardness variation between batches (caused by inconsistent DOP dosing), skinning/gelling issues during compounding, and color instability at high plasticizer loadings. Many small compounders in Delhi-NCR operate with manual weighing systems that introduce ±5% variation in every batch.

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## Likely cause

This issue often stems from inconsistent compounding temperatures, inferior raw material purity, or unbalanced stabilizer ratios within the formulation matrix.

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## Corrective direction

Consistent footwear granules start with **NBT SG-7 Resin (K-70)**  -  the higher K-value provides better mechanical properties at the high plasticizer loadings used in footwear (45-60 PHR DOP). Pair this with **NBT DOP** that has verified specific gravity and refractive index to ensure batch-to-batch consistency. For the compounding process, we recommend using a Banbury mixer with automated DOP injection (by weight, not volume) to eliminate human dosing errors. NBT can supply pre-validated resin-plasticizer combinations that have been tested in our lab for the target hardness range, so you get predictability from day one.

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          ## Frequently Asked Questions

          
### What's the ideal Shore A for different sole types?

Slippers: 50-60. School shoes: 65-75. Industrial boots: 80-90. The target determines your PHR ratio.

### Can DOTP replace DOP in footwear granules?

Yes, at a similar PHR. DOTP gives slightly better low-temperature flexibility and migration resistance, useful for export-grade footwear.

        
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By NBT Technical Desk · Updated 2026-06-07

        

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