How to reduce the formaldehyde content in the production process of silicone hip pads?

How to reduce the formaldehyde content in the production process of silicone hip pads?

1. Analysis of formaldehyde sources
1.1 Introduction of raw materials
In the production of silicone hip pads, raw materials are an important source of formaldehyde pollution. Some silicone raw materials may be added with formaldehyde-containing additives during the production process to improve the performance of silicone, such as enhancing its flexibility or stability. According to relevant research, the formaldehyde content in some inferior silicone raw materials can be as high as 300mg/kg, which is far beyond the safety standard. In addition, the glue used to bond silicone parts may also contain formaldehyde. In order to reduce costs, some low-quality glues use formaldehyde as a raw material or preservative, and the formaldehyde release can reach more than 500mg/kg. These formaldehydes will be gradually released during the use of silicone hip pads, causing potential harm to human health.
1.2 Production process
The production process of silicone hip pads may also lead to the generation of formaldehyde. During the high-temperature molding process, if the temperature is not properly controlled, some organic components in the silicone may decompose and produce formaldehyde. For example, when the temperature exceeds 200°C, the organic silanol groups in some silicones may decompose and release formaldehyde. In addition, poor ventilation during the production process can also cause formaldehyde to accumulate in the workshop. According to tests, the formaldehyde concentration in a poorly ventilated workshop can reach 0.5mg/m³, which is much higher than the national indoor formaldehyde concentration standard of 0.08mg/m³. This not only affects the health of workers, but may also cause the product to absorb more formaldehyde during the production process, further increasing the formaldehyde content in the product.

2. Raw material control measures
2.1 Select high-quality silicone raw materials
Selecting high-quality silicone raw materials is the key first step to reduce the formaldehyde content of silicone hip pads. High-quality silicone raw materials strictly control the use of additives during the production process to avoid adding formaldehyde-containing substances. For example, the formaldehyde content of silicone produced by some well-known brand silicone raw material suppliers can be controlled below 10mg/kg, which is much lower than the formaldehyde content of inferior raw materials. When purchasing, companies should require suppliers to provide quality inspection reports for raw materials and clarify key indicators such as formaldehyde content. In addition, enterprises can establish long-term cooperative relationships with suppliers to jointly develop low-formaldehyde or even formaldehyde-free silicone raw materials to reduce the introduction of formaldehyde from the source.
2.2 Strict screening of additives
In the production of silicone hip pads, the use of additives is inevitable, but they must be strictly screened. For additives that enhance flexibility and stability, formaldehyde-free or low-formaldehyde products should be preferred. For example, some new environmentally friendly additives have almost negligible formaldehyde release and are comparable in performance to formaldehyde-containing additives. When choosing glue, low-quality products with formaldehyde as a raw material or preservative should be avoided. There are a variety of formaldehyde-free glues available on the market, and their bonding properties are stable and can meet production needs. Enterprises should conduct strict testing of additives before use to ensure that their formaldehyde content meets the standards. At the same time, establish an evaluation system for additive suppliers, regularly review the product quality of suppliers, and ensure that the additives used always meet environmental protection and safety requirements.

3. Production process optimization
3.1 Adjustment of vulcanization process parameters
Vulcanization process is a key link in the production of silicone hip pads, and the reasonable adjustment of its parameters is crucial to reducing the formaldehyde content.
Temperature control: Studies have shown that when the vulcanization temperature is controlled at 150℃~180℃, the possibility of organic components in silicone decomposing and producing formaldehyde is greatly reduced. In this temperature range, silicone can complete the vulcanization reaction well, while avoiding the risk of formaldehyde release caused by high temperature. For example, a company reduced the formaldehyde content in the product by about 30% by adjusting the vulcanization temperature from 200℃ to 170℃.
Time control: Appropriate vulcanization time helps silicone to fully cross-link, form a stable network structure, and reduce the generation of formaldehyde. In general, the vulcanization time should be accurately set according to the type of silicone and the thickness of the product. For common silicone hip pads, the vulcanization time is recommended to be controlled at 10 minutes to 15 minutes. Too short a time may lead to incomplete vulcanization and affect product quality; too long a time may cause unnecessary side reactions. Data shows that when the vulcanization time is extended from 8 minutes to 12 minutes, the formaldehyde content of the product can be reduced by about 25%.
Pressure adjustment: Appropriate vulcanization pressure can promote the close bonding between silicone molecules and reduce the decomposition of organic components. Generally, the vulcanization pressure should be maintained at 5MPa~10MPa. Within this pressure range, silicone can be evenly stressed and complete a good vulcanization process. Experiments show that by increasing the vulcanization pressure from 4MPa to 8MPa, the formaldehyde content in the silicone hip pad can be reduced by about 20%, and the physical properties of the product are also significantly improved.
3.2 Optimize the molding process
The optimization of the molding process can effectively reduce the generation and residue of formaldehyde.
Improvement of mold design: Reasonably design the structure and size of the mold to ensure that the silicone is heated evenly during the molding process to avoid local overheating and formaldehyde release. The use of a split mold can make the silicone heat more evenly during molding and reduce the decomposition of organic components caused by uneven temperature. In addition, optimizing the exhaust system of the mold can timely discharge the gas generated during the molding process, including possible formaldehyde, and reduce the residual formaldehyde in the product. After a certain company adopted a new mold design, the formaldehyde content of the product was reduced by 15%.
Adjustment of molding temperature and time: Similar to the vulcanization process, the reasonable control of molding temperature and time is equally important. Controlling the molding temperature at 140℃~160℃ and the molding time at 5 minutes~10 minutes can not only ensure the molding quality of the silicone hip pad, but also effectively reduce the generation of formaldehyde. Experimental data show that within this temperature and time range, the formaldehyde content of the product can be reduced by about 35%, and the appearance and performance of the product meet excellent standards.
Optimization of ventilation system: A good ventilation system can timely discharge formaldehyde gas in the workshop to prevent it from being adsorbed on the surface of the product during the production process. Installing efficient ventilation equipment in the molding workshop to ensure that the number of air changes per hour reaches more than 10 times can reduce the formaldehyde concentration in the workshop to below 0.05mg/m³, which is far lower than the national indoor formaldehyde concentration standard. This not only helps protect workers’ health, but also reduces the adsorption of formaldehyde by the product, so that the formaldehyde content of the final product meets safety standards.

4. Quality testing and monitoring
4.1 Establish formaldehyde testing standards
Establishing strict formaldehyde testing standards is a key link in ensuring the quality and safety of silicone hip pads. At present, the country has clear limit standards for the formaldehyde content of silicone products. For example, the formaldehyde emission in silicone products shall not exceed 0.05mg/m²·h. Based on this, enterprises should establish more stringent internal testing standards in combination with their own product characteristics and higher quality requirements. For example, a well-known silicone product company sets the formaldehyde content standard of silicone hip pads to no more than 0.03mg/m²·h, which is far lower than the national standard and effectively guarantees the safety of the product. In terms of testing methods, advanced testing technologies such as high-performance liquid chromatography (HPLC) or gas chromatography (GC) can be used. These methods have the characteristics of high sensitivity, high selectivity, rapidity and accuracy, and can accurately measure the formaldehyde content in silicone hip pads. At the same time, enterprises should regularly calibrate and maintain testing equipment to ensure the accuracy and reliability of test results.
4.2 Regular sampling of products
Regular sampling is an important means to ensure that the formaldehyde content of silicone hip pads continues to meet the standards. Enterprises should formulate detailed sampling inspection plans, specify the frequency, sample size and scope of sampling inspection. For example, a comprehensive sampling inspection of silicone hip pads on the production line is carried out once a month, with a sample size of no less than 10 pieces each time, covering products of different batches and production dates. During the sampling inspection, the formaldehyde detection standards are strictly followed, and the test results are recorded and analyzed in detail. Once a product with excessive formaldehyde content is found, the traceability procedure should be started immediately to find the cause of the problem, such as raw material quality problems, production process deviations, etc., and take corresponding corrective measures, such as changing raw material suppliers, adjusting production process parameters, etc. At the same time, a comprehensive investigation and treatment of the same batch of products that have been produced should be carried out to prevent unqualified products from entering the market. Through regular sampling inspections and strict follow-up treatment measures, the quality stability of silicone hip pads can be effectively guaranteed and consumers’ trust in the products can be enhanced.

5. Environment and equipment management
5.1 Workshop ventilation
Workshop ventilation is an important environmental management measure to reduce the formaldehyde content in the production process of silicone hip pads.
Ventilation system design: The workshop should be equipped with an efficient ventilation system to ensure smooth air circulation. The design of the ventilation system should be determined according to the layout of the workshop, the distribution of production equipment, and the formaldehyde release during the production process. For example, a combination of mechanical ventilation and natural ventilation is adopted, and the air in the workshop can be quickly updated by installing high-power ventilation equipment and reasonably setting the position of the vents. According to research, a good ventilation system can reduce the formaldehyde concentration in the workshop by more than 50%.
Ventilation frequency requirements: In order to effectively discharge the formaldehyde gas in the workshop, the ventilation frequency of the ventilation system should meet certain standards. Generally speaking, the ventilation frequency of the silicone hip pad production workshop should be no less than 12 times/hour. For example, after a certain enterprise implemented a ventilation frequency of 15 times per hour, the formaldehyde concentration in the workshop was reduced from the original 0.3mg/m³ to 0.06mg/m³, which is far lower than the national indoor formaldehyde concentration standard, which not only improves the working environment of the workers, but also reduces the adsorption of formaldehyde by the product.
Ventilation equipment maintenance: Regular maintenance and maintenance of ventilation equipment is the key to ensuring the normal operation of the ventilation system. Enterprises should formulate detailed ventilation equipment maintenance plans, including regular inspections of the operating status of ventilation equipment, cleaning of ventilation ducts, replacement of filters, etc. For example, a comprehensive inspection and maintenance of ventilation equipment every quarter can ensure that the ventilation efficiency of the ventilation system is always maintained at a high level, thereby effectively reducing the formaldehyde concentration in the workshop.
5.2 Equipment cleaning and maintenance
The cleaning and maintenance of production equipment are also crucial to reducing the formaldehyde content in the production process of silicone hip pads.
Cleaning frequency and method: Production equipment should be cleaned regularly to prevent residual silicone materials from decomposing on the surface of the equipment to produce formaldehyde. The cleaning frequency should be determined based on the use of the equipment and the characteristics of the products produced. For example, for molding equipment, surface cleaning should be performed after each production to remove residual silicone debris and impurities. The cleaning method can be a combination of physical cleaning and chemical cleaning, such as using a soft brush to remove dust and debris on the surface of the equipment, and then wiping it with a formaldehyde-free detergent to ensure that the surface of the equipment is clean and free of residue.
Equipment maintenance plan: Formulate a detailed equipment maintenance plan and regularly inspect and maintain production equipment to effectively reduce the generation of formaldehyde caused by equipment failure. The maintenance plan should include inspection, lubrication, replacement and other operations of key equipment components. For example, regularly check the sealing performance of the molding mold to prevent local overheating caused by poor sealing and formaldehyde generation; calibrate and maintain the heating system of the vulcanization equipment to ensure the accuracy of temperature control, thereby reducing the risk of formaldehyde release caused by temperature fluctuations. According to statistics from a certain company, after implementing a strict equipment maintenance plan, the formaldehyde content in the product has decreased by about 10%.
Equipment update and upgrade: With the continuous advancement of technology, timely updating and upgrading of production equipment can effectively reduce the generation of formaldehyde. For example, adopting new production equipment with low formaldehyde release, or technically transforming existing equipment, installing formaldehyde adsorption devices, etc. A certain company introduced advanced molding equipment, and the formaldehyde content of its products was reduced by 20% compared with the same type of products produced by old equipment, which shows that equipment updates and upgrades have a significant effect in reducing formaldehyde content.

6. Personnel training and management
6.1 Formaldehyde hazards and protection training
Formaldehyde is a harmful substance that has many hazards to human health. During the production of silicone hip pads, workers may be exposed to formaldehyde, so it is crucial to train them on formaldehyde hazards and protection.
Hazard awareness: Formaldehyde mainly enters the human body through the respiratory tract, skin and digestive tract. Short-term exposure to high concentrations of formaldehyde can cause irritation of the eyes, nose, throat and respiratory tract, and symptoms such as tearing, coughing, and wheezing; long-term exposure to low concentrations of formaldehyde may cause allergic reactions, respiratory diseases, and even increase the risk of cancer. According to studies, long-term exposure to an environment with a formaldehyde concentration of 0.1mg/m³ will increase the risk of nasopharyngeal cancer by 30%.
Protection training content: Enterprises should organize training regularly to explain the hazards of formaldehyde to workers in detail so that they fully realize the importance of protection. At the same time, the training should cover the correct protection methods, such as wearing personal protective equipment such as masks, gloves, and goggles. For example, the use of activated carbon masks can effectively filter more than 90% of formaldehyde in the air, reducing the risk of workers inhaling formaldehyde. In addition, workers should be taught how to use ventilation equipment correctly, as well as emergency treatment methods when abnormal situations such as formaldehyde leaks are found.
6.2 Standardized operating procedures
Standardized operating procedures are an important guarantee for reducing the formaldehyde content in the production process of silicone hip pads, and can also ensure the health and safety of workers.
Operation process formulation: Enterprises should formulate detailed and standardized operating procedures based on the characteristics of production processes and equipment. These processes should cover all aspects from the receipt, storage, and use of raw materials to product molding, testing, and packaging. For example, in the raw material storage link, it is stipulated that silicone raw materials and additives should be stored in a well-ventilated, cool and dry warehouse to avoid formaldehyde release due to improper environmental conditions; in the product molding link, the precise control range of parameters such as vulcanization temperature, time, and pressure is clarified to ensure that workers strictly follow the standard operation and reduce the generation of formaldehyde.
Training and assessment: Train workers on the operation process so that they can master the specific operation requirements of each link. After the training, a strict assessment is carried out to ensure that workers can accurately and correctly perform the operation process. For example, by simulating the operation scene, the actual operation of the workers is scored, and the workers who fail the assessment are retrained until they fully master the standardized operation process. According to statistics from a certain company, after implementing standardized operating process training, the formaldehyde content in the product decreased by 15%, and the production efficiency also increased by 10%.
Supervision and feedback: Establish a supervision mechanism to ensure that workers can always follow the standardized operating procedures in the actual production process. Arrange special personnel to regularly check the workers’ operations and correct irregular behaviors in a timely manner. At the same time, encourage workers to put forward suggestions for improving the operating procedures to form a good feedback mechanism. For example, a certain company set up a suggestion box and held regular employee seminars to collect workers’ opinions and suggestions on the operating procedures, optimized the operating procedures, further reduced the formaldehyde content, and improved product quality.

7. Summary
Through the above comprehensive study on the control of formaldehyde content in the production process of silicone hip pads, the following key conclusions and suggestions can be summarized:
7.1 Key conclusions
Raw material selection is crucial: high-quality silicone raw materials and formaldehyde-free additives are the basis for reducing formaldehyde content. Selecting raw materials with low or even no formaldehyde content can reduce the introduction of formaldehyde from the source. For example, the formaldehyde content of silicone produced by a well-known brand silicone raw material supplier can be controlled below 10mg/kg, while inferior raw materials may be as high as 300mg/kg.
The optimization effect of production process is significant: reasonable adjustment of vulcanization and molding process parameters, such as controlling the vulcanization temperature at 150℃~180℃, the vulcanization time at 10 minutes~15 minutes, the vulcanization pressure at 5MPa~10MPa, and optimizing mold design, molding temperature and time, can effectively reduce the generation of formaldehyde. Data show that through these optimization measures, the formaldehyde content of the product can be reduced by 20%~35%.
Environmental and equipment management cannot be ignored: good workshop ventilation and cleaning and maintenance of production equipment can effectively reduce the accumulation and adsorption of formaldehyde during the production process. The ventilation system has a ventilation frequency of more than 12 times/hour, which can reduce the formaldehyde concentration in the workshop to below 0.05mg/m³; equipment cleaning and maintenance can reduce the formaldehyde content of the product by about 10%.
Quality inspection and monitoring are guarantees: Establishing strict formaldehyde detection standards and regular sampling mechanisms can ensure that the formaldehyde content of the product continues to meet safety standards. Advanced detection technologies such as high performance liquid chromatography (HPLC) or gas chromatography (GC) can accurately measure formaldehyde content; regular sampling and strict follow-up treatment measures can effectively ensure the stability of product quality.
Personnel training and management are the key: training workers on formaldehyde hazards and protection, as well as training and assessment of standardized operating procedures, can not only reduce formaldehyde content, but also ensure the health and safety of workers. After implementing standardized operating procedure training, the formaldehyde content of products can be reduced by 15% and production efficiency can be increased by 10%.
7.2 Recommendations
Continuously improve the quality of raw materials: Enterprises should work closely with suppliers to jointly develop low-formaldehyde or even formaldehyde-free silicone raw materials and additives to eliminate the introduction of formaldehyde from the source. At the same time, strengthen the evaluation and review of raw material suppliers to ensure that the purchased raw materials always meet environmental protection and safety requirements.
Deepen production process optimization: Enterprises should continuously explore and apply more advanced production process technologies to further optimize vulcanization and molding process parameters. For example, introduce intelligent production equipment and control systems to achieve accurate monitoring and automatic adjustment of the production process, thereby more effectively reducing the generation of formaldehyde.
Strengthen environmental and equipment management: Enterprises should regularly upgrade and renovate workshop ventilation systems and production equipment to ensure that ventilation efficiency and equipment cleaning and maintenance are in the best condition. At the same time, establish a complete equipment update and upgrade mechanism, timely eliminate old equipment with high formaldehyde release risks, and introduce new production equipment with low formaldehyde release.
Strengthen quality inspection and monitoring: Enterprises should further improve formaldehyde detection standards and sampling mechanisms, increase detection frequency and sample size, and ensure that the formaldehyde content of products is strictly controlled within a safe range. At the same time, strengthen the analysis and application of detection data, timely discover potential quality problems, and take effective preventive and corrective measures.
Pay attention to personnel training and management: Enterprises should incorporate personnel training into long-term development plans, regularly organize formaldehyde hazard and protection training and standardized operation process training, and improve workers’ environmental awareness and operating skills. At the same time, establish a complete supervision and feedback mechanism to encourage workers to actively participate in quality improvement activities and form a good atmosphere of full participation and joint management.
To sum up, through comprehensive measures such as raw material control, production process optimization, environment and equipment management, quality inspection and monitoring, personnel training and management, the formaldehyde content in the production process of silicone hip pads can be effectively reduced, the quality and safety of the products can be guaranteed, the health of consumers can be protected, and it will also contribute to the sustainable development of the enterprise.