\n| Softening<\/td>\n | Select a special softener for polyurethane, with moderate molecular weight, good compatibility with the system, and high stability<\/td>\n | Evonik Tego, Momentive Silsoft<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n1.3 Ratio optimization<\/h3>\nThe ratio of raw materials directly affects the performance of the foam. The following are the common raw material ratio range:<\/p>\n \n\n| Raw Materials<\/th>\n | Rating range (parts by weight)<\/th>\n | Remarks<\/th>\n<\/tr>\n | \n\n| Polyether polyol<\/td>\n | 100<\/td>\n | Benchmark raw materials<\/td>\n<\/tr>\n | \n| Isocyanate<\/td>\n | 40-60<\/td>\n | Adjust according to hydroxyl value and NCO content<\/td>\n<\/tr>\n | \n| Water<\/td>\n | 2-5<\/td>\n | Footing agent, the amount of the foam affects the density of the foam<\/td>\n<\/tr>\n | \n| Catalyzer<\/td>\n | 0.1-0.5<\/td>\n | Adjust according to the reaction speed<\/td>\n<\/tr>\n | \n| Softening<\/td>\n | 1-3<\/td>\n | Adjust to foam softness requirements<\/td>\n<\/tr>\n | \n| Other additives<\/td>\n | 0.5-2<\/td>\n | such as flame retardants, antioxidants, etc.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n2. Production process optimization<\/h2>\n2.1 Foaming process control<\/h3>\nThe foaming process is the core link in the production of soft foam and directly affects the structure and performance of the foam. The following are the key control points of the foaming process:<\/p>\n \n\n| Process Parameters<\/th>\n | Control Range<\/th>\n | Impact<\/th>\n<\/tr>\n | \n\n| Mixing Temperature<\/td>\n | 20-30\u2103<\/td>\n | Temperature too high will lead to excessive reaction, and temperature too low will lead to insufficient reaction<\/td>\n<\/tr>\n | \n| Agitation speed<\/td>\n | 1000-3000 rpm<\/td>\n | The stirring speed affects the uniformity of the bubbles, and too high will cause the bubbles to burst<\/td>\n<\/tr>\n | \n| Foaming time<\/td>\n | 5-10 minutes<\/td>\n | The foaming time is too short, which will lead to uneven foam density, and too long may lead to foam collapse<\/td>\n<\/tr>\n | \n| Mature temperature<\/td>\n | 50-80\u2103<\/td>\n | The maturation temperature affects the degree of crosslinking of the foam. Too high temperature may cause the foam to harden<\/td>\n<\/tr>\n | \n| Mature Time<\/td>\n | 2-4 hours<\/td>\n | The maturation time is too short, which will lead to insufficient foam strength, and too long may affect production efficiency<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n2.2 How to add softener<\/h3>\nThe addition of softener has a significant impact on foam performance. Common ways to add include:<\/p>\n \n- Premix method<\/strong>: Premix the softener with polyether polyol in advance, and then perform a foaming reaction. This method can ensure that the softener is evenly dispersed in the system and is suitable for large-scale production. <\/li>\n
- Post addition method<\/strong>: After the foaming reaction reaches a certain level, add a softener. This method is suitable for occasions where there are special requirements for foam softness, but it is difficult to operate. <\/li>\n<\/ul>\n
2.3 Process Optimization Example<\/h3>\nThe following is a typical soft foam production process optimization example:<\/p>\n \n\n| Process Steps<\/th>\n | Pre-optimization parameters<\/th>\n | Optimized parameters<\/th>\n | Optimization effect<\/th>\n<\/tr>\n | \n\n| Mixing Temperature<\/td>\n | 25\u2103<\/td>\n | 22\u2103<\/td>\n | Reduce the reaction speed and reduce bubble burst<\/td>\n<\/tr>\n | \n| Agitation speed<\/td>\n | 2000 rpm<\/td>\n | 2500 rpm<\/td>\n | Improve bubble uniformity and reduce bubble density differences<\/td>\n<\/tr>\n | \n| Software addition method<\/td>\n | Add method<\/td>\n | Premix method<\/td>\n | Improve the uniformity of softener dispersion and improveFoam softness<\/td>\n<\/tr>\n | \n| Mature temperature<\/td>\n | 70\u2103<\/td>\n | 60\u2103<\/td>\n | Reduce the maturation temperature to prevent the foam from becoming harder<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n3. Finished product inspection and quality control<\/h2>\n3.1 Physical performance test<\/h3>\nThe physical properties of soft foam products are an important indicator for measuring their quality. The following are common physical performance testing items:<\/p>\n \n\n| Test items<\/th>\n | Testing Standards<\/th>\n | Qualification Range<\/th>\n | Remarks<\/th>\n<\/tr>\n | \n\n| Density<\/td>\n | ASTM D3574<\/td>\n | 20-50 kg\/m\u00b3<\/td>\n | Often the density may lead to insufficient foam strength, and too high may affect softness<\/td>\n<\/tr>\n | \n| Resilience<\/td>\n | ASTM D3574<\/td>\n | \u226540%<\/td>\n | Low resilience may shorten the service life of the foam<\/td>\n<\/tr>\n | \n| Tension Strength<\/td>\n | ASTM D3574<\/td>\n | \u226580 kPa<\/td>\n | Tension strength is too low may cause the foam to tear<\/td>\n<\/tr>\n | \n| Tear Strength<\/td>\n | ASTM D3574<\/td>\n | \u22652 N\/cm<\/td>\n | Tear strength is too low may cause the foam to burst<\/td>\n<\/tr>\n | \n| Compression permanent deformation<\/td>\n | ASTM D3574<\/td>\n | \u226410%<\/td>\n | Overlasting compression deformation may cause the foam to lose elasticity<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n3.2 Chemical performance test<\/h3>\nThe chemical properties of soft foam products directly affect their durability and safety. The following are common chemical performance testing items:<\/p>\n \n\n| Test items<\/th>\n | Testing Standards<\/th>\n | Qualification Range<\/th>\n | Remarks<\/th>\n<\/tr>\n | \n\n| VOC content<\/td>\n | ISO 16000-6<\/td>\n | \u2264100 \u00b5g\/m\u00b3<\/td>\n | VOC content is too high and may be for peopleHealth causes harm<\/td>\n<\/tr>\n | \n| Formaldehyde emission<\/td>\n | GB 18587<\/td>\n | \u22640.05 mg\/m\u00b3<\/td>\n | Excessive formaldehyde emission may cause harm to human health<\/td>\n<\/tr>\n | \n| Flame retardant performance<\/td>\n | GB 8624<\/td>\n | Level B1<\/td>\n | Unqualified flame retardant performance may lead to fire hazards<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n3.3 Finished product inspection process<\/h3>\nThe following is the finished product inspection process for soft foam products:<\/p>\n \n- Sampling<\/strong>: Randomly sampled from the production line to ensure that the sample is representative. <\/li>\n
- Physical Performance Test<\/strong>: According to standard testing methods, the density, resilience, tensile strength, tear strength, permanent compression deformation of the sample is tested. <\/li>\n
- Chemical performance test<\/strong>: Test the VOC content, formaldehyde emission, flame retardant properties of the sample. <\/li>\n
- Data Analysis<\/strong>: Compare the test results with the pass range to analyze whether there are quality problems. <\/li>\n
- Feedback and Improvement<\/strong>: Adjust the production process in a timely manner according to the test results to ensure stable product quality. <\/li>\n<\/ol>\n
IV. Frequently Asked Questions and Solutions<\/h2>\n4.1 Uneven foam density<\/h3>\nProblem Description<\/strong>: The density of foam products is unevenly distributed, and the density in some areas is too high or too low. <\/p>\nPossible Causes<\/strong>:<\/p>\n\n- The stirring speed is uneven, resulting in uneven bubble distribution. <\/li>\n
- The amount of foaming agent is inaccurate, resulting in uneven foaming. <\/li>\n
- The softener is unevenly dispersed, affecting the foam structure. <\/li>\n<\/ul>\n
Solution<\/strong>:<\/p>\n\n- Adjust the stirring speed to ensure even distribution of bubbles. <\/li>\n
- Accurately control the amount of foaming agent to ensure uniform foaming. <\/li>\n
- Add softener by premixing method to ensure uniform dispersion. <\/li>\n<\/ul>\n
4.2 Inadequate foam resilience<\/h3>\nProblem Description<\/strong>: Foam products have poor resilience and recover slowly after pressing. <\/p>\nPossible Causes<\/strong>:<\/p>\n\n- Inadequate amount of softener is used, resulting in too low elastic modulus of foam. <\/li>\n
- The maturation temperature is too high, resulting in excessive crosslinking of foam. <\/li>\n
- The amount of catalyst is used too much, resulting in too fast reaction and unstable foam structure. <\/li>\n<\/ul>\n
Solution<\/strong>:<\/p>\n\n- Increase the amount of softener to improve foam elasticity. <\/li>\n
- Reduce the maturation temperature and avoid excessive foam crosslinking. <\/li>\n
- Reduce the amount of catalyst and control the reaction rate. <\/li>\n<\/ul>\n
4.3 Low foam tear strength<\/h3>\nProblem Description<\/strong>: Foam products are prone to tear and have a short service life. <\/p>\nPossible Causes<\/strong>:<\/p>\n\n- The molecular weight of the polyether polyol is too low, resulting in insufficient foam strength. <\/li>\n
- Insufficient isocyanate usage, resulting in low foam crosslinking. <\/li>\n
- The softener has poor compatibility with the system, affecting the foam structure. <\/li>\n<\/ul>\n
Solution<\/strong>:<\/p>\n | | | | | |
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