Industrial DPNP sourcing solutions involve processes such as melting, mixing, molding, and curing. During these processes, one may come into contact with high temperatures, high pressures, flammable and volatile monomers / additives, and may also produce dust and toxic gases. Fire prevention, explosion prevention, poisoning prevention, mechanical injury prevention, and high-temperature burns prevention are the core safety points. The specific requirements for different processing techniques (such as injection molding, extrusion, compression molding, winding, gluing, etc.) vary slightly. The following are general and mandatory safety matters that must be followed, covering the entire processing process:
I. Preparations: Material and Environmental Control
Material Classification Management
Synthetic resins (such as epoxy resin, polyurethane, phenolic resin, acrylic resin) and their accompanying additives (curing agents, diluents, plasticizers, solvents) are mostly flammable, explosive and toxic substances (such as benzene-based solvents, isocyanates, amine curing agents). They need to be stored in accordance with the requirements for hazardous chemicals: be stored separately in a cool and ventilated warehouse away from fire sources / heat sources, strictly prohibit mixed storage with acids, alkalis and oxidants, and be equipped with leak containment berms and emergency adsorption materials; the usage follows the principle of "small quantities and multiple uses", and no stockpiling is allowed on-site.
The working environment meets the standards.
The processing workshop must have good ventilation and be equipped with a forced exhaust system (especially in the enclosed molding areas). Special exhaust treatment devices should be installed for toxic and harmful gases (such as formaldehyde, styrene, and isocyanates). Smoking and the use of open flames are strictly prohibited in the workshop. Bringing fire sources is also forbidden. Fire prevention and explosion-proof warnings as well as static discharge devices should be set up at the entrance of the workshop.
Equipment and Tools Inspection
Before starting the machine, check whether the temperature control, pressure, and transmission systems of the processing equipment (such as injection molding machines, extruders, mixers, hot presses, etc.) are normal, and whether the safety protection devices (protective covers, emergency stop buttons, over-temperature/over-pressure alarms) are in good condition; check that the pipelines (raw material transportation, cooling water, steam) have no leakage, and that the electrical equipment is explosion-proof (suitable for processes with solvent evaporation), to avoid dangerous electrical sparks.
II. Core Process: Operational Safety Standards
(1) Melting / Mixing / Plasticizing (high-temperature processes such as injection molding, extrusion, granulation, etc.)
Strictly control the temperature, rotation speed and pressure according to the resin process parameters to avoid resin decomposition and carbonization due to overheating, and to prevent the generation of toxic gases (such as formaldehyde released by phenolic resin when overheated, and hydrogen chloride released by polyvinyl chloride when overheated). Even in extreme cases, it may cause the materials to spontaneously ignite.
When operating high-temperature equipment, wear heat-resistant protective gloves, goggles and heat-resistant work clothes. Avoid direct contact with molten resin, high-temperature feeders and molds to prevent burns. It is strictly prohibited to clean the sticky materials inside the equipment with hands directly. Use special tools (copper scrapers to avoid sparks).
If there is a blockage or overpressure during the operation of the equipment, stop the machine, cool it down and relieve the pressure before handling the issue. It is strictly prohibited to operate under pressure. When cleaning the remaining materials in the equipment, do it only after the materials have completely cooled down to prevent the splashing of residual hot materials.
(2) Formation / Solidification (molding, pouring, winding, bonding, etc.)
When applying resins that are diluted with solvents (such as unsaturated polyester and epoxy resins), proper ventilation must be ensured. Wear a gas mask / activated carbon mask and nitrile gloves to prevent inhalation of solvent vapors and skin contact (some solvents / curing agents are corrosive and allergenic; for example, isocyanates can irritate the respiratory tract and skin).
During the curing process, if there are exothermic reactions (such as polyurethane and epoxy resin curing at room temperature), the feeding volume and curing environment temperature need to be controlled to prevent localized heat accumulation, which could lead to excessive polymerization and expansion of the material, or even cracking of the mold. For large-sized products during curing, temperature measurement points need to be set to monitor the temperature in real time.
During manual operations (such as layering and pouring), avoid making the site messy to prevent tripping and falling. When using pressurized molding equipment (such as hot presses and hydraulic presses), ensure that the mold is firmly positioned and strictly prohibit extending hands or arms into the mold closing area to prevent crushing injuries.
(III) Cutting / Polishing / Post-processing
When cutting and polishing resin products, resin dust will be generated. It is necessary to wear dust masks and goggles, install dust collection devices in the working area, and regularly clean the dust to prevent inhalation of the dust which may cause respiratory diseases, or dust explosion when it accumulates and comes into contact with an open flame (such as polystyrene and polypropylene dust).
When using cutting and grinding equipment, check that the protective cover is intact. It is strictly prohibited to remove the protective device for operation. During operation, maintain a safe distance between your hands and the cutting tools / grinding wheels to prevent mechanical injuries.
When dealing with post-treatment of chemicals (such as desoldering and cleaning), use dedicated cleaning solvents to avoid reactions with resins or additives, which could produce toxic gases. The waste liquid after cleaning should be collected in accordance with hazardous chemical requirements and must not be discharged at will.
III. Material Contact: Poison Prevention and Protection
Skin protection: Avoid direct contact with chemicals such as resins, curing agents, and solvents. When working, wear chemical-resistant gloves (made of nitrile or chloroprene rubber, avoid using latex gloves as they are easily corroded by solvents). Wear long-sleeved work clothes and protective shoes. If the skin comes into contact with chemicals, immediately rinse with plenty of water. After coming into contact with corrosive materials (such as strong acid curing agents), first rinse with weak alkaline solution (such as soapy water), and then seek medical attention.
Respiratory protection: Select protective equipment based on the working environment: Wear an activated carbon anti-toxic mask/safety goggles when there is solvent evaporation; wear a positive pressure air respirator when the concentration of toxic gases is high; wear a KN95 or higher dust mask in dusty environments to avoid long-term inhalation of dust.
Eye protection: Wear goggles throughout the process to prevent resin liquid, solvents, dust, and debris from entering the eyes. If the eyes come into contact with contaminants, immediately rinse with clean water for at least 15 minutes and seek medical attention promptly.
Emergency eyewash stations and shower facilities should be set up at the work site and kept ready for use at all times; regular occupational health checks should be conducted for the workers to detect any damage to the respiratory system, skin or eyes.
IV. Equipment and Electrical: Key to Fire and Explosion Prevention
All processing areas where solvent evaporation or flammable gas generation occurs must be equipped with flammable gas detectors, smoke alarms, and be linked to the exhaust system and fire-fighting equipment. When the levels exceed the standard, they will automatically trigger an alarm and activate the exhaust system.
The electrical equipment, lines and switches are all of explosion-proof grade compatibility (such as Ex d IIB T4), to prevent fires and explosions caused by electrical sparks and static sparks; the operators wear anti-static work clothes and anti-static shoes, and the raw material transportation and equipment are well grounded to prevent static electricity accumulation.
In the workshop, dry powder fire extinguishers, carbon dioxide fire extinguishers, and fire sand (suitable for resin fires; strictly prohibit water for extinguishing molten resin and solvent fires) are properly equipped in accordance with regulations. Firefighting equipment is placed in easily accessible locations and is regularly checked for effectiveness.
During equipment maintenance, the machine should be shut down, power disconnected, and warning signs hung. The flammable materials in the barrel and pipelines should be cleared and replaced. After the concentration of combustible gases is detected to be within the standard range, the maintenance work can be carried out to avoid sparks generated during the maintenance process from causing danger.
V. Waste and Emergency: Requirements for Follow-up Management
Waste Disposal: The waste materials (resin waste, adhesive waste, solvent waste liquid, dust) generated during the processing are classified as hazardous chemicals and collected by qualified units for disposal. It is strictly prohibited to discard or incinerate them at will (some resin incineration may produce highly toxic gases such as dioxins); waste such as rags and gloves contaminated with chemicals are sealed and centrally disposed of.
Emergency for Residue and Solvent Leakage: In case of residue or solvent leakage, immediately stop the machine, cut off the fire source, and evacuate the personnel at the scene; use sand and absorbent cotton to absorb the leaked substances. It is strictly prohibited to rinse with water (as the solvent will spread with the water flow, expanding the danger range); after ventilating the leakage area, proceed with the cleanup. The cleaned-up waste should be treated as hazardous waste.
Accident handling: In case of a fire, immediately activate the fire-fighting equipment, cut off the power supply, evacuate the personnel, and call 119; in case of poisoning, burns, or mechanical injuries, immediately take emergency measures (such as rinsing and bandaging), and send to the hospital for treatment; the workshop has formulated a special emergency plan and regularly organizes emergency drills.
VI. Personnel Management: Training and Policies
All workers must undergo professional safety training and operation training, be familiar with the physical and chemical properties, process parameters and safety risks of the resin they process, master emergency response methods, and only be allowed to work after passing the assessment; unauthorized operation and illegal operation are strictly prohibited.
Establish and improve safety management systems, including equipment operation procedures, hazardous chemicals management systems, and work permit systems (such as firework operations and confined space operations require approval); regularly maintain and service equipment, protective devices, and fire-fighting equipment, and keep records.
Clear safety warning signs (for fire prevention, explosion prevention, poison prevention, mechanical injury prevention, and the requirement to wear protective equipment, etc.) should be set up at the work site. Unrelated personnel are strictly prohibited from entering the processing area.
VII. Special Resins: Key Safety Points for Specific Applications
Some synthetic resins have specific safety requirements that require extra attention:
Polyurethane resin: The isocyanate monomer is prone to absorbing moisture and decomposing, generating toxic gases. It will react vigorously when in contact with amines or water. During storage and operation, keep it dry. Strictly prohibit contact with water, acids, and alkalis; During curing, there is a significant heat release, and the amount of material added must be strictly controlled.
Phenolic resin: When processed at high temperatures, formaldehyde is released. Adequate ventilation is necessary and a special mask for formaldehyde protection should be worn. After the resin solidifies, it becomes brittle and generates a lot of dust during grinding. Therefore, enhanced dust prevention measures should be taken.
Unsaturated polyester resin: Uses styrene as the crosslinking agent. Styrene is volatile, flammable and toxic. No open flames are allowed in the operation area. Enhance ventilation to prevent the accumulation of vapors.
Polyvinyl chloride (PVC): During high-temperature processing (above 180℃), it is prone to decomposition and release hydrogen chloride. The processing temperature must be strictly controlled. An acidic gas absorption device should be equipped, and the operators should wear acid-proof protective gear.
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