Importanted step is testing whether the raw materials

Printed documents corresponding to each batch of raw materials must be filed by category for future reference.

Individual Raw Material Testing (Incoming inspection; mandatory for every batch)

1. Binder Resin (Polyester / Styrene-Acrylic resin; the main component of toner)

- Glass transition temperature (Tg), melt index (MI), and softening point: Determine fusing temperature, tendency to stick to rollers, and low-temperature fusing performance.
- Acid value and molecular weight distribution: Affect charge stability and susceptibility to moisture-induced clumping.
- Moisture, ash content, and impurities.

2. Colorants (Carbon black / Color pigments)

- Carbon black: DBP oil absorption, blackness, ash content, volatile matter, and grit (high grit levels can scratch the drum core).
- Color pigments: Hue, tinting strength, dispersibility, and heat resistance (color stability at high fusing temperatures).

3. Charge Control Agent (CCA)

- Charging polarity, charge quantity, and stability across temperature/humidity ranges; issues like background fog or toner scattering upon environmental changes are usually caused by the CCA.

4. Release Wax (PE wax / Carnauba wax)

- Melting point and melting range; improper melting points lead to sticking to fusing rollers, ghosting, or poor release performance.

5. External Additives (SiO₂, TiO₂)

- Particle size, BET specific surface area, and hydrophobicity; control flowability, charging characteristics, and anti-clumping properties. Insufficient additives result in poor flowability, while excessive amounts cause wear on the drum and carrier.

II. Finished Toner Powder: Physicochemical Testing (After raw material blending)

1. **Particle Size Distribution & Grit** (Laser particle size analyzer + sieving): Wide particle size distribution and large particles can scratch the photosensitive drum, causing black spots or black lines.
2. **Moisture Content**: ≤0.8%; high moisture leads to clumping, unstable charging, and increased background fog.
3. **Bulk Density** / 4. **Cohesion**: Affects flowability and the uniformity of powder delivery; poor powder supply leads to faint printing.
5. **Charge-to-Mass Ratio (Q/M)**: A critical electrostatic parameter; excessive charge causes powder scattering, while insufficient charge leads to background fogging; charge decay is measured under varying temperature and humidity conditions (to assess environmental adaptability).
6. **Caking Test**: Involves aging tests under high/low temperatures and humidity to simulate maritime shipping or warehouse storage conditions and evaluate storage stability.
7. **Resistivity**: Affects image development and transfer.