Solvent Free Leather Production Solution
Industry Pain Points
Mechanical Challenges in Coating Precision and Uniformity
Difficulty in controlling accuracy:
Precise control of coating application and mechanical precision are two key factors limiting the development of solvent-free laminating machines-3. Even slight deviations in the speed difference or gap accuracy between the coating roller and the metering roller can cause significant fluctuations in the coating amount.
Poor uniformity:
Traditional top-coating methods tend to leave excessive coating residue on the base fabric, which not only wastes material but also causes the base fabric to warp and become damaged due to the excessive coating thickness.
Hydrolytic degradation: Polyester-based PU is prone to hydrolysis in humid or high-temperature environments, causing the sole to become brittle, crack, and flake off—a problem that is particularly pronounced in southern regions and during the rainy season.
Process window issues caused by material reaction characteristics
Quick-setting:
After mixing and reacting, solvent-free slurry hardens to some extent within a short period of time; ambient temperature and the low temperature of the roller blade itself accelerate this process.
Blocking Guns and Sticking Knives:
It is difficult to precisely control the reaction time, and issues such as nozzle clogging and material sticking to the blade often arise during use-4. This forces production lines to shut down frequently for cleaning, and these shutdowns cause the unused slurry to harden further, resulting in waste.
Thermal Management and Cleaning Design for Equipment
Lack of active temperature control:
If the roller knife and piping are not equipped with a heating and insulation system, the slurry will solidify more quickly in low-temperature environments. The current solution involves installing a heating layer inside the roller knife to maintain the slurry temperature and prevent solidification.
Difficulty in cleaning and changing materials:
Compared to EVA (lightweight and inexpensive), rubber (wear-resistant), and TPU (tough and resilient), single-density PU offers no distinct advantages and lacks value for money.
Core of the Solution
Haifeng Automation, a veteran in the polyurethane automation equipment industry, focuses on the core demands of “comprehensive protection, long-lasting durability, green environmental protection, and intelligent efficiency”. It integrates independently accumulated solvent-free/water-based PU technology, precision manufacturing processes, and intelligent quality control systems, integrating core equipment and process solutions into the entire industrial chain of safety shoes. Leveraging technical experience in PU foaming equipment, precision metering systems, and other fields, it achieves four core goals, adapts to multi-scenario needs, and provides integrated “technical solution + equipment implementation” services.
Core Solution Modules
R&D of Scenario-Specific Specialized Materials
Ingredients and formulation：
A1, A2 (polyester polyol), B1, B2 (isocyanate), C1-C4 (color paste)
Proportion range of raw materials: 100:40-100
Preheating temperature of raw materials: 20-40°C
Other ingredients: Cleaning agent (MC: for cleaning the machine head), nitrogen (function: to prevent material deterioration), compressed air (function: power source)
Pouring capacity：
Maximum instantaneous flow rate: 100 g/s (6 kg/min)
Low-density products (e.g., apparel leather, thin furniture leather): 300g/sm
Heavy-duty products (e.g., shoe leather, heavy furniture leather): 600g/sm
Applicable products: Solvent-free synthetic leather (foamed/mirror finish type)
Measurement accuracy 3
Specific Process
| Phase 1: Production Preparation | ||
|---|---|---|
| Raw Material Preparation and Loading | Raw materials A, B, and color slurry (C1-C4) are separately conveyed to the corresponding storage tanks of the equipment. Subsequently, the system performs constant temperature heating and continuous stirring of the raw materials within the tanks. |  |
| Equipment Preparation and Parameter Settings | Initiate the full-path temperature control system for preheating, then retrieve the predetermined production formula from the main control panel to set all process parameters with one click. Finally, execute automatic cleaning and trial operation to verify the status of all equipment systems and the mixing effluent quality. |  |
| Kibb preparation | Mount the release paper or base fabric (e.g., non-woven fabric, knitted fabric) onto the unwinding device, and pull it through the entire coating line. |  |
| Phase II: Coating Production | ||
| Precision Measurement and Mixing | The metering pump delivers each component of raw materials precisely according to the formula ratio, which is then collected through insulated pipelines to the pouring head. Within the pouring head, the raw materials achieve uniform mixing. |  |
| Coating and Forming | The cast truss drives the head to perform precise reciprocating motion, ensuring uniform coating on the base fabric surface, followed immediately by surface texture formation via the embossing roller. | |
| Reaction curing and molding | The coated wet film enters the drying tunnel. After curing completion, the product proceeds to the cooling section for temperature reduction. |  |
| Rolling and ripening | The cooled synthetic leather (if release paper is used, it is collected together with the release paper) is automatically wound up. The wound-up product requires aging in a constant-temperature warehouse for 24-48 hours to ensure complete reaction and achieve stable performance. |  |
| Post-processing and Inspection | If release paper is used, it should be separated from the synthetic leather after maturation using a peeling machine.Surface treatment: Post-processing such as embossing, printing, spraying, or embossing may be required to achieve specific appearance and tactile characteristics. Inspection and packaging: The finished product undergoes inspection for appearance, thickness, and physical properties (e.g., wear resistance, hydrolysis resistance). Upon passing inspection, the product is packaged and stored. |  |
Equipment List and Unit Price
| order number | name | quantity | Specification Parameters | Unit price (United States dollars) |
|---|---|---|---|---|
| 1 | Solvent-free PU Blending System | 1 set | Measurement accuracy: ±0.5% | |
| 2 | Casing machine | 1sets | Maximum coating width: 1800mm | |
| 3 | Oven system | 1 set | Length: 25 meters Temperature range: Room temperature to-150°C | |
| 4 | coolant passage | 1 set | Hydraulic cooling + air cooling combination | |
| 5 | batch up gear,batching apparatus | 1 set | Maximum winding diameter with automatic tension control: 1200mm | |
| 6 | Release Paper Treatment System | 1 set | Including unwinding, alignment correction, and winding devices | |
| 7 | Central Control System | 1 set | PLC + Human-Machine Interface, Recipe Storage Function |
Technical parameters
Coating machine system
| Tank system: A1 and B1 with a capacity of 500 liters (2 sets), A2 and B2 with a capacity of 50 liters (1 set each). Materials: Inner layer made of 304 stainless steel, middle layer with a heating layer, and outer layer with polyurethane rigid foam insulation.Measurement System: A1A2 high-precision metering pump (25cc, 1 set each), B1B2 high-precision metering pump (20cc, 1 set each). Motor: 1.3KW servo motor with planetary reducer.Color additive system: High-precision metering pump 0.6cc (4 sets), 50-liter storage tank, Drive motor: 0.75KW servo motorFrame system: Left-right digitalized movement (1 set): The moving motor is a 0.75KW servo motor; Up-down digitalized movement (1 set): The moving motor is a 1.0KW servo motor. Head system: Needle valve-type head (1 set), driven by servo motor Head cooling system: 2 chillers (1 unit) Nose cleaning system: 20-liter cleaning tank (1 unit) Vacuum system: 30L vacuum pump (1 unit), A Feeding System: Diaphragm pumps (2 units), B Feeding System: Manual feeding or vacuum pump feeding, Rack assembly: Frame structure (1 set), with aluminum alloy doors Control System: PLC; various models of modules (1 set); |
|
Oven system
| Heating method: Hot air circulation + infrared auxiliary heating Temperature control range: room temperature to-150°C Temperature control accuracy: ±1℃ Number of heating zones: 6 zones with independent temperature control Rated voltage: 380V Power consumption: approximately 120-150 kW |
 |
coolant passage
| Function of the cooling roller: A large-diameter metal drum with circulating cooling water inside, through which the fabric passes in close contact with its surface, and heat from the fabric is removed via thermal conduction.Cooling roller body: The material is typically steel or stainless steel.Roll surface temperature: 10°C–25°C (adjusted according to production line speed and requirements)Cooling water temperature: 7°C-15°C Roll diameter: 500 mm–1000 mm (typically) Surface treatment: Electroplated hard chrome or mirror-polished finish |
|
Coiling device system
| Function: The synthetic leather product, after completion of coating, curing, and cooling, is wound into rolls with constant tension and neat edges to facilitate storage, transportation, and subsequent processing.Maximum coil diameter: Φ1000mm, Φ1500mmMaximum roll width: 1800mm, 2200mmMaximum linear speed: 10-30 meters per minute Tension control range: 50–500 N Control mode: Automatic/manual, Constant tension/conical tension control Power supply requirements: 380V/3-phase/50Hz Drive system: AC servo motor or frequency converter |
 |
Release Paper Treatment System
| Function: Ensure the release paper is used flatly and stably in the production process while protecting it from damage, and allow for reuse.Maximum paper roll width: 1800mm-2500mmMaximum unwinding/unwind diameter: Φ1000mm, Φ1500mmInner diameter of the core: 3 inches or 6 inches Maximum mechanical speed: 30-50 meters per minute Tension control range: 50-500N Tension control accuracy: ±1%–±5% Correction accuracy: ±1 mm Total power: 5-15KW Power supply: 3-phase, 380VAC, 50Hz |
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Production output and production efficiency
| production pattern | Heavy-duty products (such as shoe leather and heavy furniture leather) | Low-density products (e.g., garment leather, thin furniture leather) |
|---|---|---|
| Product weight (based on actual measurement) | 600(g/sm) | 300(g/sm) |
| Effective working width | 1.6m | 1.6m |
| The theoretical maximum linear speed V = extrusion volume / (gross weight × width) | V = 100 g/s / (600 g/sm × 1.6 m) ≈ 0.104 ≈ 6.25 |
V = 100 g/s / (300 g/sm × 1.6 m) ≈ 0.208 ≈ 12.5 |
| Daily production (16 hours) (16小时) |
Area: 9,600 square meters per day | Area: 19,200 square meters/day |
| Annual output (300 days) | 2,880,000 square meters per year | 5,760,000 square meters per year |
Working Conditions
| subject of entry | requirement |
| Workshop Requirements | Cleanroom, with an area of approximately 30m×10m and a minimum height of 5 meters |
| humiture | Temperature: 20–30°C; Humidity: 40–70% RH |
| current source | 3×380V±5%,50Hz, total power approximately 250kW |
| compressed air | 0.6-0.8 MPa, dry and oil-free, flow rate approximately 1.5 m³/min |
| water coolant | Circulating cooling water, pressure 0.3–0.4 MPa, temperature ≤25°C |
| operation staff | Each shift consists of 3-4 personnel (including the main operator, assistant workers, and quality inspector). |
Full-Process Automated Production System
Integrated production line
Provide customized complete production lines covering all processes from raw material pretreatment to intelligent sorting. Core equipment adopts Haifeng’s independently developed imported configuration, ensuring material mixing uniformity ≥98% and stable and reliable operation.
Customized adaptation
Rely on the CAD modeling and 3D printing capabilities of the Mechanical Design Research Institute to quickly produce customized molds and non-standard components, shortening the R&D cycle of new styles to 7-10 days.
Existing equipment transformation
Install Haifeng’s intelligent temperature control, precision proportioning, and automated conveying modules to realize the transformation from solvent-based to solvent-free/water-based processes, reducing labor and raw material losses.
Comprehensive Quality Verification and Compliance Assurance
Intelligent quality inspection
Equip Haifeng’s independently developed integrated testing equipment, covering thickness, defect, bonding strength, and key performance tests. With an efficiency of ≥50 pairs per minute, defective products are automatically sorted out.
Real-time control
Adopt Haifeng’s intelligent production control system to dynamically adjust parameters, controlling the defect rate at 2-3%; integrate environmental monitoring modules to achieve near-zero VOC emissions.
Certification support
Cooperate with authoritative testing institutions to assist in completing multi-standard certifications, providing technical parameters and sample support to help obtain CE and LA certifications and break through high-end market barriers.
Solution Value and Effects
| Dimension | Traditional Process | Haifeng Automation Solution | Improvement Effects |
|---|---|---|---|
| Compliance Rate of Protective Performance | Below 85% | Above 99% | Meet national/international standards and eliminate safety hazards |
| Defect Rate | 10-15% | 2-3% | Reduce by over 75% and minimize rework losses |
| Raw Material Waste Rate | ≥15% | ≤5% | Reduce by 67%, saving over 300,000 yuan in raw material costs per line annually |
| Labor Requirement | 8-10 people/line | 2-3 people/line | Reduce by 75% and lower the risk of operational errors |
| VOC Emissions | Excessive | Near zero | Achieve environmental compliance and obtain international certifications |
| R&D Cycle | 30-45 days | 7-15 days | Shorten by over 60% for rapid market response |
Implementation Process
Demand Research
Technical team conducts on-site investigations to formulate personalized solutions.
Formula and Process Design
Complete customization and feasibility verification relying on the R&D Center.
Equipment Customization/Transformation and Commissioning
Factory completes production, with engineers conducting on-site installation and commissioning.
Small-Batch Trial Production
Technical team tracks and optimizes parameters.
On-Site Installation and Mass Production
Implement the production line and start mass production, providing technical guidance.
Quality Inspection and Certification Support
Assist in completing testing and certification applications.
After-Sales Operation and Maintenance
Provide maintenance and upgrading services relying on the national service network.
