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Method for improving cold-cured high-resilience molded foam products

1 Introduction Polyurethane cold-cured molded foam products are mainly used to produce car seats and headrests. Compared with hot molded products, they have simple processing technology, moderate mold temperature (45-70°C), and low energy consumption; and have excellent physical properties, Short mold time and high production efficiency. In 2012, it exceeded 19 million vehicles. The competition among the supporting auto interior companies has become increasingly fierce, and the cost of land rent, human resources, raw materials, and transportation has continued to rise, but it is difficult to absorb the increased cost in the product price. Faced with the difficulties of reality, companies can only gain space for continued survival and profitability through changes. The improvement of fast demoulding and high physical properties of the system material can greatly reduce labor costs, and can reasonably reduce the density of the product under the premise of ensuring the physical properties of the product, thereby generating new profit points. 2. Introduction For many years, TM20 (TDI/PAPI=80:20) and TM50 (TDI/PAPI= 50:50) and other TDI-rich mixed isocyanates for production, the advantages are: high TDI-rich NCO content, low P/I ratio can reduce the amount of black material, low cost; rich TDI-produced foam, Good elasticity, high tear strength, good fluidity of the system material, and relatively low product density. Disadvantages are that pure TDI is currently a highly toxic drug and is controlled by the Ministry of Public Security; TDI has a certain impact on the health of on-site operators; system materials rich in TDI mature slowly, which affects production efficiency; foams produced by rich TDI are soft. Due to the low price of TDI in recent years, from the perspective of cost, isocyanates rich in TDI are very cost-effective, and from the perspective of operator health, it is necessary to reduce the amount of TDI. The TM50 system is a relatively moderate ratio: the physical properties and cost are moderate, and the purchase is more convenient. However, it is still necessary to solve the problem of slow efficiency caused by slow maturation, insufficient foam with high physical properties, and slightly higher density. Generally speaking, slow maturation can be solved by adding foaming catalyst A1 and gel catalyst A33, but increasing the amount of A33 will cause the foam gel speed to be too fast, and it is easy to produce too late to close the mold or product flow dissatisfaction, missing corners, Undesirable phenomena such as voids can easily cause shrinkage and flatulence of the product, which will affect the performance of the foam. The physical properties of foam are generally set by OEMs. In recent years, OEMs have been continuously improving their physical properties. The most common physical properties such as tear strength must not be less than 2.0 N/cm, and those with high requirements must be greater than 2.3-2.5 N/cm; The tensile strength should not be less than 90Kpa, and the high requirements should be greater than 100-120Kpa. The compression set is increased from less than 10% to less than 5%. Under the condition that the isocyanate is relatively fixed, it is necessary to conduct research from the combined polyether component, and select the appropriate polyether, polymer polyol and crosslinking agent, silicone oil, catalyst, etc. The density is generally set by the OEM, but the general OEM will give a certain range. For example, some OEMs require a seat of 45±5Kg/m3. If the density range of 40-42 can meet the performance requirements of the OEM, This can also reduce costs. Generally reducing density is achieved by adding water. Water is a chemical blowing agent, which generates CO2 by reacting with isocyanate to generate gas, thereby reducing the density of the product. However, if there is too much water, the water-isocyanate reaction (blowing reaction) in the system will be greater than the polyol-isocyanate reaction (gel reaction), resulting in peeling, hollow center, and even bubble collapse. Therefore, when choosing a relatively fixed isocyanate system, another main raw material is polyether and polymer polyol. Fixing a polyether system is beneficial to cost control. Taking into account the basic performance requirements and cost factors of the current OEMs, polyether polyols can choose from 4800 molecular weight to 6000 molecular weight, polymer polyols can choose 3628 (28% solid content), H45 (43% solid content) and other common commonly used Types, domestic manufacturers such as Shanghai Gaoqiao, Tianjin San Petrochemical, Jinpu Kumho, Zhongshan Petrochemical, Shandong Dongda, etc. Setting such standard polyether products is easy to purchase, price is transparent, the supply chain is smooth, and the entire cost is easier to control. Under the choice of a fixed isocyanate and polyether system (330N to POP ratio), it is necessary to improve physical properties and process performance, mai