The hottest way to improve cold cured high rebound

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Methods for improving cold cured high resilience molded foam products

(Shanghai Yexing Industrial Co., Ltd. 200436) Abstract: This paper introduces the process, performance improvement and recent technical progress of allchem's new polyurethane additives for cold cured high resilience molded foam products such as automotive seats and headrests. Key words: cold curing high resilience polyurethane additive 1 Polyurethane cold curing molded foam products are mainly used in the production of car seats and headrests. Compared with hot molded products, they have the advantages of simple processing technology, moderate mold temperature (℃), and low energy consumption; It has the advantages of excellent physical properties, short demoulding time and high production efficiency. However, with the rapid development of economy, especially in recent years, China's automobile production and sales volume has ranked first in the world for four consecutive years, and exceeded 19million in 2012. With the increasingly fierce competition among the supporting automobile interior decoration enterprises, the costs of land rent, human resources, raw materials and transportation are rising, but it is difficult to absorb the increased costs in the product price. In the face of various difficulties in reality, enterprises can only obtain the space to continue to survive and make profits through change. The improvement of system materials with fast demoulding and high physical properties can greatly reduce labor costs, and reasonably reduce the density of products on the premise of ensuring the physical properties of products, so as to generate new profit points. 2. For many years, cold cured high resilience products are mostly produced with TDI rich mixed isocyanates such as TM20 (tdi/papi=80:20), TM50 (tdi/papi=50:50). The advantages are: the content of NCO rich in TDI is high, the low p/i ratio can reduce the amount of black material, and the cost is low; Foam rich in TDI has good elasticity, high tear strength, good fluidity of system material and relatively low product density. The disadvantages are that pure TDI is currently highly toxic and controlled by the Ministry of public security; TDI has a certain impact on the health of field operators; The clinker of the system rich in TDI is slowly maturing, which affects the production efficiency; Foam rich in TDI is soft. Due to the low price of TDI in recent years, isocyanate rich in TDI has a high cost performance ratio in terms of cost. From the perspective of the health of operators, it is necessary to reduce the amount of TDI. TM50 system is a relatively moderate proportion: the physical property and cost are moderate, and the procurement is relatively convenient. However, it is still necessary to solve the problems of slow efficiency caused by slow aging, unsatisfied foam with high physical properties, and slightly higher density. Generally speaking, the slow aging can be solved by increasing the foaming catalyst A1 and the gel catalyst A33. However, increasing the amount of A33 will cause the speed of Foam Gel to be too fast, which is easy to produce undesirable phenomena such as insufficient time for mold closing or product flow dissatisfaction, corner missing, cavity, etc., and it is easy to cause the shrinkage and inflation of products, which will affect the performance of foam. The physical properties of foam are generally set by the host plant. In recent years, the host plant is also constantly improving the physical properties. The most common physical properties such as tear strength should not be less than 2.0 n/cm, and the high requirements should be greater than 2 5 N/cm; The tensile strength shall not be less than 90kpa, and the tensile strength with high requirements shall be greater than kPa. The compression setting is increased from less than 10% to less than 5%. Under the condition of relatively fixed isocyanate, it is necessary to study the components of combined polyether, and select the appropriate polyether, polymer polyol and crosslinker, silicone oil, catalyst, etc. Generally, the density is also set by the main engine factory, but generally the main engine factory will give a certain range. For example, some main engine factories require 45 5kg/m3 for seats. If the performance requirements of the main engine factory can be met in the density range, the cost can also be reduced. Generally, density reduction is achieved by increasing water. Water is a chemical foaming agent. It reacts with isocyanate to generate CO2 to produce gas, thereby reducing the density of products. However, once 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, central cavity, and even bubble collapse. Therefore, when choosing a relatively fixed isocyanate system, the other main raw materials are polyether and polymer polyol. Fixing a polyether system is conducive to cost control. Considering the basic performance requirements and cost factors of the current main engine plant, 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 types, domestic manufacturers such as Shanghai Gaoqiao, Tianjin sanpetrochemical, Jinpu Jinhu, Zhongshan petrochemical, Shandong Dongda, etc. Setting such standard polyether products is easy to purchase, transparent in price, smooth in supply chain, and easy to control the whole cost. When choosing a fixed isocyanate and polyether system (330n to pop ratio), it is necessary to improve the physical properties and process performance, mainly relying on new additives. This paper mainly discusses the influence of additives on the performance and process conditions of the whole foam. Because the proportion of additives in the whole system is low, the application of additives can give foam new vitality at the minimum cost. 3. Experiment 3.1 main raw materials and equipment isocyanates: toluene diisocyanate lupranate TDI BASF product polyphenyl polymethylene polyisocyanate suprasec 5005 Huntsman product polyether: polyether polyol ep-330n Shandong Dongda product polymer polyol pop-93/28 Shandong Dongda product silicone oil: tegostab B 8738 LF2 Evonik Degussa product catalyst: allchem is Shanghai Yexing Industry Co., Ltd The company's product allchem A-1 70% bis (2-methylaminoethyl ether) bdmaee +30% dipropylene glycol DPG allchem a-3333% triethylenediamine TEDA +67% dipropylene glycol DPG allchem dy-7 new compound amine catalyst allchem dy-9 new compound amine catalyst 3.2 formula and process 3.2.1 experimental results, it is impossible to judge the pre preparation of isocyanate component B, Table 1 Table 1 Ingredient raw material (weight fraction) formula lupranate TDI 50 suprasec 5005 50

3.2.2 experimental equipment manual mixer, rotating speed 2000 rpm; Aluminum mold with circulating water, size 400mm*400mm*100mm; Super constant temperature water bath, control mold temperature 55 ℃; A. The temperature of component B is tested at 25 ℃; 3.2.3 the production method is based on the weighing of component A: component B =100:55 (weight ratio), and the isocyanate index is 100. Pour it into the mold after rapid mixing, close the mold, and take the mold after curing. The appearance of the skin is good, without peeling and adverse phenomena, and the foam does not shrink. 3.2.4 the density of standard products for physical property test shall be determined according to gb/t method; The collapse load shall be measured according to gb/t method; Elongation shall be determined according to gb/t method; The tear strength shall be measured according to gb/t method; Compression set is determined according to gb/t method. 3.2.5 foaming data are as follows: Table 2 Table 2 component raw material (weight fraction) formula 1 Formula 2 Formula 3 formula 4 ep-330n 50 50 50 50 50 pop-93/28 50 50 50 50 50 50 50 50 water 444 allchem A-1 0.15 0.1 ------ allchem a-33 0.4 0.55 ------ allchem dy-7 ------ 0.2 0.4 allchem dy-9 ------ 0.6 0.4 tegostab 8738 LF2 0.6 0.6 0.6 diethanolamine 1.5 1.5.5 1.5 TM50 (index 100) 58.7 58.7 58.7 58.7 foaming process milky time s s s s wire drawing time 52s 50s 71s 68s demoulding time (mold temperature 55 ℃) 6 minutes and 30 seconds 6 minutes and 30 seconds 3 minutes and 30 seconds 3 minutes product density kg/m3 40 40 40 40 foam performance indentation load 25% n 114 121 116 118 indentation load 65% n 326 349 322 330 elongation% 92 95 101 105 tear strength n/cm 1.8 1.85 2.02 2.11 compression permanent deformation% before fatigue 6.37 6.32 6.35 6.29 1 compression permanent deformation% after fatigue 10.51 10.28 8.76 8.19

1 compression 70%, 70 ℃, 22h4 Results and discussion 4.1 improvement of foaming equipment. From table 2, it can be seen that formula 3 and 4 use allchem dy-7 and dy-9 new compound catalysts, the Milky time and wire drawing time are significantly reduced, which is more conducive to the production of large seats, such as car rear seats, three seat minibus, and truck rear sleeper. The weight of a single foam exceeds 3kg. At present, some domestic manufacturers use low-pressure machines to produce seats. The flow rate of the machine is g/S. for products with small single seats, backrests and other products, and a single foam of less than 1.5kg, the injection time can be completed in seconds (close to the Milky time of foam). However, for a single foam with the weight of foam greater than 2kg, the low-pressure machine will not be able to achieve it. Using allchem dy-7 and dy-9 new compound catalyst can prolong the injection time of seconds, which is suitable for large foam with the weight of less than 3kg. For foam products over 3kg, low-pressure or high-pressure machines with large flow should be selected, and the flow rate should be greater than 300g/s. 4.2 improvement of production efficiency compared with traditional amine catalysts A-1 and A33, the new compound catalyst allch cleaning cylinder piston EM dy-7 and dy-9 can greatly improve the ripening time, and the demoulding time can be accelerated from 6.5 minutes to 3 minutes to 3.5 minutes. Formula 4 is the recommended formula. It has the fastest demoulding speed and good skin ripening. It is especially suitable for circular assembly lines. At present, customers using allchem dy-7 and dy-9 have the fastest lap speed of 2 minutes and 40 seconds, which greatly reduces labor costs and production costs. 4.3 improvement of foam performance as the density of foam decreases, the physical properties of foam also decrease. It can be seen from table 2 that when the density of foam products is 40kg/m3, the data of formulas 1 and 2, tear strength, elongation and compression set are not ideal; Using allchem dy-7 and dy-9, you can meet the performance requirements of most OEMs. At present, the main engine manufacturers pay special attention to compression set, and the compression set after fatigue requires strong physical properties of foam, which is easier to meet the standard when allchem dy-7 and dy-9 are used. Some foam with high requirements, such as tear strength 2 (7) Implement the industrial innovation and development service organization training project 3n/cm, and extend the visit rate by 120%, which also needs to increase the density of foam. 4.4 improvement of foaming formula because the prices of TDI and MDI often change, properly adjusting the proportion of isocyanate mixing according to the price change is conducive to the reduction of cost. Using allchem dy-7 and dy-9 new compound catalysts, material B can change from TM20 (tdi80%+mdi20%) to tm60 (tdi40%+mdi60%), while material a does not need to be significantly changed, only the proportion of polyether polyols and polymer polyols needs to be changed to ensure the hardness of the product. However, the physical properties need to be proportional according to specific examples, which is independent of the parameters in Table 2. 5. Technological progress 5.1 low model temperature catalyst recently, the country has promoted energy conservation and emission reduction, and the power consumption cost of production enterprises is large. Some customers choose to produce at night in order to reduce the power consumption cost and avoid peak hours. If the mold temperature can be reduced in the production process, the production efficiency will not be affected, and the loss of heat energy can be greatly reduced, so as to reduce the production cost. Allchem dt-301 newly launched by allchem company can reduce the mold temperature required for production. Compared with ordinary catalysts, it can reduce the mold temperature by about degrees. For fully modified MDI system, the mold temperature can be reduced to ℃, for TM50 system, the mold temperature can be reduced to ℃. TM20 system can be reduced to ℃. 5.2 improvement of foam with high physical properties the OEMs gradually improve the performance of foam, especially tear strength, tensile strength and elongation index. Because the composition of black material is relatively fixed in manufacturing enterprises, especially in some foreign-funded factories, some adopt modified MDI system, while the main engine factory requires that the tear strength and tensile strength of foam should reach the physical properties of TDI foam, such as tear strength greater than 3n/cm, tensile strength greater than kPa. Allchem dl-6501 can significantly improve the tear strength and tensile strength, and is suitable for all MDI systems and TM systems. 5.3 improvement of low VOC and low odor foam in recent years, all OEMs are improving the VOC concentration and odor in the car. Polyurethane foam products related to it, such as car seats, headrests, steering wheels, instrument panels, ceilings, carpets, front walls and other products, are used

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