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material： ABS and Nitrile Rubber

ABS processing

1. Monomer Mixing and Pre-polymerization

Raw material ratio: Styrene (St) : Acrylonitrile (AN) : Butadiene (Bd) = 50-70% : 20-30% : 10-20%.

Initiator: Azo diisobutyl nitrile (AIBN) or Di-t-butyl peroxide (DTBP).

Pre-polymerization: Partial polymerization at high temperature (80-100°C) until a conversion rate of 10-20% is achieved, forming oligomers.

2. Continuous Bulk Polymerization

Reactor: Tower or kettle reactor, pressure 0.5-1.5 MPa, temperature 100-130°C.

Process control:

Gradually increase temperature to promote reaction, achieving a final conversion rate of 60-80%.

Remove unreacted monomers (styrene, acrylonitrile) via vacuum devolatilization.

Nitrile Rubber Production Process

Emulsion Polymerization

1. Monomer Pre-treatment

Acrylonitrile (AN): Dehydrate to moisture content <0.05% to prevent side reactions forming acidic substances.

Butadiene (BD): Wash with alkali to remove sulfides and oxygen impurities, avoiding chain transfer reactions.

Emulsifier: Sodium dodecyl sulfate (SDS) or rosin acid soap, used to stabilize the latex.

Initiator: Potassium persulfate (KPS) or AIBN, initiating free radical polymerization.

2. Polymerization Reaction

Ingredient ratio: Acrylonitrile 18-50% (affects oil resistance and elasticity), Butadiene 50-82%.

Reaction conditions:

Temperature: 40-60°C (controls molecular weight distribution).

pH: Adjusted to 7-8 (prevents acidic substances from inhibiting polymerization).

Process control:

Monomers are added gradually to maintain latex stability.

Reaction time 6-12 hours, conversion rate 60-80%.

3. Post-processing

Coagulation: Add a salting-out agent (e.g., NaCl or Na₂SO₄) to coagulate the latex into particles.

Washing: Multiple water washes to remove residual emulsifiers and unreacted monomers.

Protective Layer

Material: Gelatin

Production Process

1. Raw Material Selection and Pre-treatment
2. Pre-treatment Process

Dehairing and Defatting:

Dehairing: Soak in sodium hydroxide (NaOH) solution (5-10% concentration) to soften and remove hair (12-24 hours).

Defatting: Remove fat and impurities using organic solvents (e.g., acetone) or alkaline detergents.

Crushing: Mechanically pulverize the skin material into fine particles (1-3 mm diameter) to increase reaction surface area.

1. Collagen Extraction

Acid Hydrolysis

Acid type: Hydrochloric acid (HCl) or citric acid (pH 1.5-2.5).

Conditions:

Temperature: 40-60°C, reaction time 12-24 hours.

Liquid-to-solid ratio: 1:10 (skin material : acid solution).

Purpose: Break down collagen into gelatin peptide chains while retaining partial triple-helix structure integrity.

1. Purification and Refinement
2. Neutralization and Washing

Neutralization: After acid hydrolysis, adjust pH to neutral using sodium carbonate (Na₂CO₃).

Washing: Multiple water washes to remove residual acids/alkalis and impurities (conductivity <1000 μS/cm).

2. Filtration and Concentration

Filtration: Remove suspended particles using a plate and frame filter press or centrifuge.

Concentration: Increase gelatin solution concentration to 10-15% via vacuum evaporation (temperature ≤60°C).

1. Forming and Drying
2. Gelation

Cooling: Cool the concentrated solution to 30-40°C to form a gel (gel strength ≥150 Bloom g).

Slicing: Cut the gel into strips (1-3 cm width) for subsequent drying.

2. Drying Process

Methods:

Natural air-drying: Low temperature (20-30°C), ventilated drying (7-10 days).

Hot air drying: Tunnel oven at 40-60°C, humidity ≤30% (24-48 hours).

Final product specifications: Moisture content ≤12%, ash content ≤2%.

Photosensitive Layer

Material: Silver Bromide

Production Process

1. Raw Material Preparation

Silver nitrate (AgNO₃): Purity ≥99.5%, dried to moisture content ≤0.1%.

Bromide (NaBr/KBr): Industrial-grade sodium bromide or potassium bromide (purity ≥98%), crushed to particle size <0.5 mm.

Reaction solvent: Deionized water (conductivity ≤1 μS/cm).

2. Chemical Reaction

Reaction equation:

 AgNO₃ + NaBr →AgBr +NaNO₃

- Process conditions:

Temperature: 25-40°C (avoid decomposition of AgBr at high temperatures).

Concentration: Silver nitrate solution 10-20% (mass fraction), bromide excess 10-20%.

Mixing method: Countercurrent stirring reaction (residence time 1-2 hours).

3. Post-processing and Purification

Filtration: Remove unreacted silver nitrate and byproduct sodium nitrate using a plate-and-frame filter press (filtrate is recycled).

Washing: Wash multiple times with cold deionized water (until filtrate conductivity <10 μS/cm).

Drying: Vacuum oven drying (temperature ≤40°C, vacuum ≤10 kPa), moisture content ≤0.5%.

Development Layer System

Hydroquinone derivatives (e.g., Metol）

Reaction:

Steps:

1. Methylation:

React p-aminophenol with dimethyl sulfate in alkaline solution.

2. Neutralization:

Add sulfuric acid to form the sulfate salt (Metol).

3. Purification:

Recrystallize from ethanol/water to remove unreacted aminophenol.

Gelatin

Steps:

1. Pre-treatment:

Cleaning and degreasing animal tissues to remove impurities.

Acid/alkali treatment (e.g., soaking in HCl or NaOH) to break down collagen fibers.

2. Hydrolysis:

Heating collagen in water (60–90°C) under acidic/basic conditions to cleave peptide bonds.

Enzymatic hydrolysis (optional) for controlled degradation using proteases.

3. Filtration:

Removing insoluble residues (e.g., bone fragments, fat) via vacuum filtration.

4. Concentration:

Evaporating water under vacuum to concentrate gelatin solution (~20–30% solids).

5. Drying:

Spray drying or drum drying to produce granulated/powdered gelatin.

6. Quality Control:

Testing for gel strength, viscosity, and purity (e.g., ash content <2%).

Back Membrane Layer

Terephthalic Acid (PTA)

Steps:

1. Oxidation Reaction:

Reaction: P-Xylene is oxidized with oxygen in acetic acid medium at 150–220°C and 10–20 bar pressure.

2. Crystallization & Separation:

Crude TPA crystallizes from the reaction mixture, filtered, and washed to remove impurities (e.g., 4-carboxybenzaldehyde).

3. Purification (Hydrogenation):

Residual byproducts (e.g., terephthalic acid dimers) are hydrogenated using palladium catalysts at 200–250°C and 20–30 bar H₂​​.

4. Drying & Packaging:

High-purity PTA (>99.8%) is dried under vacuum and pelletized for polyester production.

Polyvinyl Alcohol (PVA)​

Steps:

1. Polymerization of VAM:

Free-Radical Polymerization: VAM is polymerized in methanol/water mixtures at 60–70°C using AIBN as initiator.

2. Solvent Recovery:

Unreacted monomer is stripped off, and PVAc is precipitated in methanol.

3. Partial Hydrolysis:

Acid-Catalyzed: PVAc is heated with dilute sulfuric acid (1–5 wt%) at 80–90°C for 2–4 hours​​ to hydrolyze ~87–99% of acetate groups.

4. Neutralization & Washing:

Hydrolyzed PVA is neutralized (pH 5–7), washed to remove residual catalysts, and dried.

5. Finishing:

PVA is ground into powder or dissolved in water for film/sheet production.

Support Layer (PET Substrate)​

PET

Steps：

1. Reaction 1: Esterification (if using DMT）
2. Polycondensation​

Polymerize BHET or PTA + EG under high temperature/pressure to form PET polymer chains

   3.Melt Extrusion​​

Melting:  PET polymer is melted in an extruder at ~290°C.

Filtering:  Remove contaminants (e.g., undissolved particles) using a melt filter.

Pelletizing:  Cool and cut the molten PET into uniform pellets for storage/transport.