Barium Sulfate BaSO4 Polymer for X-ray Shielding BOPET Film

Semi-dull Barium Sulfate Polyester Masterbatch

Barium sulfate (BaSO₄) polyester chip is a concentrated composite material where ultrafine BaSO₄ particles are uniformly dispersed within a polyester carrier resin.

Key Advantages

  1. Superior Density & Weighting

    • Boasts density up to 4.0 g/cm³ (vs. 1.3-1.4 g/cm³ for pure polyester)

    • Ideal for counterweights, vibration damping, and balance components.

  2. X-ray & Gamma Ray Shielding

    • The high atomic mass of barium provides exceptional radiation attenuation

    • Critical for:

      • Medical equipment (aprons, CT scanner parts)

      • Nuclear shielding

      • Aerospace components

  3. Enhanced Mechanical Properties

    • Improves stiffness (+30-50%) and dimensional stability

    • Reduces warpage in thin-walled parts

  4. Chemical Resistance

    • Resists acids, alkalis, and solvents better than mineral-filled composites

  5. Aesthetics & Surface Quality

    • Delivers bright white coloration and high gloss finish

    • Minimal impact on transparency at low loadings (<15%)

Production Methods

Two production methods are twin-screw extrusion granulation and polymerization process addition (in-situ polymerization).
▶ 1. Twin-Screw Compounding Process
Process Flow:

Feedstock Prep: Dry polyester (PET/PBT) chips/recyclate + surface-treated BaSO₄ powder (silane/titanate coupling agents) + additives.

Pre-mixing: Dry-blend components uniformly.

Extrusion: Melt-mix in a co-rotating twin-screw extruder → high shear disperses BaSO₄.

Devolatilization: Remove moisture/VOCs via vacuum vents.

Melt Filtration: Screen impurities.

Pelletizing: Strand-cut into masterbatch pellets.

Drying/Packaging.

Advantages:

✅ Mature & flexible technology

✅ Lower CAPEX (vs. polymerization)

✅ Fast production (continuous process)

✅ Easy formula adjustments (filler: 30-85%)

✅ Accepts recycled polyester

✅ Quick product changeovers

Disadvantages:

⚠️ Limited dispersion (agglomeration risk)

⚠️ Weaker polymer-filler interface bonding

⚠️ Potential polymer degradation (MW loss)

⚠️ High energy consumption

⚠️ Demands ultra-fine BaSO₄ powder

Specs:

Testing Items Unit Standard Test Value Testing Method
Value of Chromatism △E ≤1.0 ≤0.40 Q/XLM03-2022
Melting Point ℃ 252±3 252 GB/T14190-2017
Intrinsic Viscosity dl/g 0.20±0.02 0.201 GB/T14190-2017
Filtration Pressure Difference (DF) MPa ≤1.50 0.80 Q/XLM03-2022
Weight of 100 particles g 3.0±0.15 3.06 Q/XLM03-2022
Moisture Content % ≤0.30 0.15 GB/T14190-2017
Irregular Chip % ≤0.20 0.09 Q/XLM03-2022
Ash Content % 60%±2% 60.1 Q/XLM03-2022
Remark 60% BaSO4 Content

▶ 2. Polymerization (In-situ) Process
Process Flow:

Feedstock Prep: Polyester monomers (PTA/DMT + MEG) + catalyst + specialty BaSO₄ slurry (in MEG) / soluble barium salts.

Esterification: Add BaSO₄ during the reaction.

Polycondensation: Synthesize polymer around BaSO₄ particles.

Pelletizing: Cut polymer melt into chips.

Advantages:

✅ Superior dispersion (nano-level)

✅ Stronger interfacial bonding

✅ Minimal polymer degradation

✅ Higher melt flow at equal loading

✅ Higher product purity

Disadvantages:

⚠️ Complex process control

⚠️ Very high CAPEX/OPEX

⚠️ Low flexibility (fixed formulas)

⚠️ Catalyst poisoning risk

⚠️ Byproduct removal challenges

⚠️ Requires ultra-pure BaSO₄ slurry

Specs

Items Unit Standard (low IV) Standard (High IV)
Intrinsic Viscosity dl/g 0.65±0.015 0.72±0.020
COOH Value mmol/Kg ≤ 35 ≤ 30
Melting Point ℃ ≥ 259 ≥ 259
Color Value L ≥ 54 ≥ 70
b 4.0±2.0 2.0±2.0
Water Content % ≤ 0.4 ≤ 0.4
Irregular Chip & Powder % ≤ 0.4 ≤ 0.4
BaSO4 Content ppm 2700±250 2700±250