全水发泡聚氨酯硬泡的开发

全水发泡聚氨酯硬泡的开发 宋聪梅  童俊  罗振扬 (江苏省化工研究所  江苏南京 210024) 摘  要：探讨了影响全水发泡泡沫性能的相关因素，研制了具有良好流动性的全水发泡聚氨酯硬泡组合聚醚。依此制备的硬质聚氨酯泡沫塑料具有良好的尺寸稳定性、优异的粘接性能和较低的导热系数，已达到或超过汽车、建筑行业对全氟泡沫的要求，具有广阔的市场前景。 关键词：聚氨酯；硬质泡沫塑料；全水发泡；聚醚多元醇 硬质聚氨酯泡沫塑料是一种很重要的合成材料，具有优异的物理机械性能和耐化学性能，尤其是导热系数低，是一种优质的隔热材料，广泛应用于冰箱、冷柜及汽车行业、建筑行业。但是由于氯氟烃（CFC）发泡剂对大气臭氧层有破坏作用，为了维护生态环境，国际公约已经对其生产和使用做出了严格的限制和规定。因此，聚氨酯工业面临的一个重要任务就是选择CFC的代用品，减少和停止CFC的应用。10多年来，以零或低ODP值的发泡剂替代氯氟烃是聚氨酯泡沫塑料行业最重大的课 题 快递公司问题件快递公司问题件货款处理关于圆的周长面积重点题型关于解方程组的题及答案关于南海问题 ，促使泡沫塑料生产技术发生重大变化。 在聚氨酯硬泡中，常用的CFC-11替代发泡剂主要有HCFC-141b为代 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 的HCFC类发泡剂、以戊烷为代表的烃类发泡剂以及水发泡剂[1]。以水作发泡剂，实际上是以水和异氰酸酯反应生成的CO2气体作发泡剂，其臭氧破坏效应ODP值为零，无毒副作用，因此水是最具吸引力的CFC-11最终替代物。而且，全水泡沫制备工艺简便，对设备的要求很低，可沿用CFC-11体系的设备，具有广阔的市场前景。但是，全水发泡体系与CFC-11体系相比存在许多不足，诸如组合聚醚粘度比较大，泡沫与基材的粘接性差、导热系数偏高等，从而限制了全水发泡聚氨酯泡沫的推广和应用[2]。 针对全水发泡体系的特点，我们通过聚醚分子结构的调整、助剂的选择，开发了低粘度的聚醚及具有良好流动性的组合聚醚，以此制备的聚氨酯泡沫塑料具有良好的尺寸稳定性、粘接性和较低的导热系数。 1  实验部分 1.1  主要原料 PE600系列聚醚多元醇，自制；聚醚多元醇A，金陵石化公司化工二厂；聚醚多元醇TNR410，天津第三石油化工厂；复合催化剂，自制；泡沫稳定剂AK-8805等，南京德美世创化工有限公司；泡沫稳定剂B-8462、B-8433等，德国高施米特公司；多异氰酸酯（PAPI），日本聚氨酯工业公司。  1.2  设备与仪器 2.5L多功能组合式聚合釜；微量水份分析仪；旋转式粘度计；恒温水浴箱；电动搅拌器，Glas-Craft公司的高压喷涂发泡机。 1.3  手工发泡 将聚醚多元醇、泡沫稳定剂、催化剂、水等混合均匀，作为A组分；以多异氰酸酯作为B组分。发泡时，调节A料、B料及模具的温度，按配方称取A、B料，混合后搅拌5～10 s，立即倒入模具使其自由发泡，同时依次测定乳白、纤维、脱粘时间，待泡沫完全熟化后测定相关性能。 1.4  组合聚醚典型配方 组合聚醚：混合多元醇  100份；泡沫稳定剂  1.5～2.5份；复合催化剂  2.0～5.0份；水  3.0～4.0份。 异氰酸酯指数  1.0～1.1 发泡时的工艺参数(室温20℃)为：乳白时间10～20 s，固化时间20～35 s。 2  结果与讨论  2.1  聚醚多元醇对全水发泡泡沫性能的影响 在聚氨酯硬泡的制备中，相对分子质量和官能度不同的聚醚或聚酯与异氰酸酯反应形成长短不一的链段，形成相应的软硬段聚集态，构成泡沫的主体结构。选用聚醚的主要依据是泡沫制品的用途，性能要求，工艺性能，原料价格等。由于全水发泡体系缺少大量的低粘度物理发泡剂的稀释与溶解作用，采用现有高粘度硬泡聚醚的配方体系，其粘度大幅增加，混合与乳化过程变得困难，反应体系的流动性变差。水与二氧化碳反应生成较多的脲键，使泡沫粘接性能下降；同时，由于二氧化碳从泡孔内向外扩散速率大于空气向泡孔内的扩散速率，使泡孔内压力降低，导致泡沫收缩，尺寸稳定性降低[3]。因此，全水发泡硬质聚氨酯泡沫技术的关键在于开发新型的低粘度、高性能硬泡聚醚多元醇。表1为采用几种聚醚多元醇配制的组合聚醚的粘度及其制得的泡沫塑料的物性。本稿中体积变化率取绝对值，下同。 表1  聚醚品种对全水发泡泡沫性能的影响 组合聚醚 ? ?? JDPU303 主体聚醚 TNR410 聚醚A PE600 组合多元醇粘度(25℃)/mPa·s 1750 2300 1200 泡沫密度/kg·m－3 35.8 37.4 38.8 压缩强度/kPa 254 256 293 拉伸强度/kPa 300 323 393 导热系数/W·(m·K)－1 0.0258 0.0263 0.0255 吸水率/％ 变形 3.4 2.3 高温体积变化率(80℃24h)/％ 0.4 0.4 0.3 低温体积变化率(－25℃24h) /％ 0.5 0.3 0.2         以脂肪族聚醚多元醇TNR410为主体聚醚的组合聚醚?，其原液的粘度明显偏大，在常温及低温环境下，发泡设备无法正常工作，需要对原液加热以降低其粘度；并且，由表1可见，以TNR410合成的硬质聚氨酯泡沫塑料易吸水变形。以聚醚A合成的硬质聚氨酯泡沫塑料，其物性虽然符合技术 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 ，但以其为主体聚醚的组合聚醚的粘度严重超标，即使在夏季也需要对其进行预热才能满足发泡设备的使用要求。采用聚醚PE600配制组合聚醚，不仅降低了组合多元醇的粘度，使其满足普通发泡设备的使用要求，而且，以PE600合成的全水发泡硬质聚氨酯泡沫塑料具有良好的物理性能。 2.2  异氰酸酯指数对硬质聚氨酯泡沫性能的影响 在硬质聚氨酯泡沫塑料的合成中，异氰酸酯指数通常大于1.0，使反应过程中有过量的异氰酸酯基团与氨基甲酸酯进行次级反应，生成脲基甲酸酯；同时异氰酸酯基团自身之间进行三聚反应，生成异氰脲酸酯，这两种链段结构的存在使硬质聚氨酯泡沫塑料具有较高的压缩强度和尺寸稳定性。发泡时的异氰酸酯指数与水发泡硬质聚氨酯泡沫塑料压缩强度和拉伸强度的关系见图1。 图1  异氰酸酯指数对泡沫塑料强度的影响 由于水发泡体系硬质聚氨酯泡沫塑料中已经存在大量刚性的聚脲链段，随着异氰酸酯指数的增加，泡沫塑料的脆性也相应增加，这就导致泡沫塑料韧性下降，拉伸强度下降。 异氰酸酯指数对全水发泡聚氨酯泡沫塑料的影响见图2。由图2可见，异氰酸酯指数增加，则交联度增加且刚性增加，高温和低温体积变化率均降低，说明尺寸稳定性增加。 1－高温(80℃24h)尺寸稳定性    2－低温(－25℃24h)尺寸稳定性 图2  异氰酸酯指数对泡沫塑料尺寸稳定性的影响 2.3  水含量及密度对硬质聚氨酯泡沫塑料性能的影响 组合聚醚中水的用量增加，与异氰酸酯反应生成更多的CO2，放出更多的热量，使得泡沫密度降低。密度的变化对泡沫塑料的性能有较大的影响。 2.3.1  水含量及密度对泡沫尺寸稳定性的影响 全水发泡泡沫塑料体系随着水用量的增加，密度降低，形成更多的开孔结构，这不仅降低了泡孔壁的强度，也加速了CO2气体的扩散，从而影响泡沫的尺寸稳定性，见图3。 1－高温(80℃24h)尺寸稳定性    2－低温(－25℃24h)尺寸稳定性 图3  密度对泡沫塑料尺寸稳定性的影响 2.3.2  水含量及密度对泡沫导热系数的影响 闭孔型硬质聚氨酯泡沫塑料的泡孔孔径很小，其导热系数主要取决于泡孔内气体的导热系数、树脂固体的导热系数及辐射传热导热系数，而气体的导热系数占泡沫导热系数的60％以上，因此泡沫内绝热气体的含量将是影响泡沫整体导热系数的关键。在泡沫密度大于30 kg/m3时,树脂固体的导热系数基本固定，而辐射传热导热系数影响很小的情况下，水分的增加将使泡沫密度降低，这有利于提高泡沫的初始绝热性能，见图4。 图4  密度对泡沫塑料导热系数的影响 2.4  交联剂对硬质聚氨酯泡沫塑料物性的影响 交联剂是聚氨酯泡沫塑料中一类比较常用的配合剂，一般为小分子的多元醇、多元胺或它们的环氧化物加成物。添加少量的交联剂可以提高聚氨酯泡沫的交联密度及闭孔率，增强泡沫的抗压强度、耐渗透性，表2比较了相同配方的情况相同用量的情况下，不同交联剂对硬质泡沫塑料物性的影响。 表2  交联剂对硬质聚氨酯泡沫塑料物性的影响 交联剂品种 甘油 三乙醇胺 CLA-1 CLA-2 无交联剂 压缩强度/kPa 253 254 280 293 177 吸水率/％ 变形 变形 3.3 2.3 变形             2.5  表面活性剂的选择 在全水发泡硬质聚氨酯泡沫发泡体系中，由于使用极性较强的水作为化学发泡剂导致发泡体系的极性增加。传统的甲基硅氧烷氧化烯烃共聚物表面活性剂的极性较强，因而它对同样呈强极性的全水硬质聚氨酯泡沫发泡体系的乳化成核作用相对较弱，难于形成细密、均匀的闭孔结构泡沫。 非水解硅酮表面活性剂是为全球范围内聚氨酯泡沫塑料CFC及HCFC 替代的趋势而开发的高活性表面活性剂。 2.5.1  表面活性剂对泡沫导热系数的影响 B8433非水解硅酮表面活性剂是德国高施密特公司专门开发的全水发泡硬质聚氨酯泡沫表面活性剂，它对水－聚醚多元醇－异氰酸酯体系有着优异的乳化成核能力，在反应过程中控制泡孔结构，并最终获得泡孔细腻均匀、绝热性能良好的硬质聚氨酯泡沫塑料。本工作在相同的主配方体系中分别采用不同的用量的不同的有机硅表面活性剂(泡沫稳定剂)，制得的泡沫塑料的导热系数见图5。 2.5.2  表面活性剂用量对泡沫尺寸稳定性的影响 随着表面活性剂用量的增加，硬质聚氨酯泡沫塑料的泡孔结构更趋向于均一化，闭孔率增加，其尺寸稳定性也相应提高，高温尺寸稳定性的改善尤为明显，见图6。    2.6  催化剂的选择 在全水发泡聚氨酯发泡体系中，传统的叔胺催化剂如N,N-二甲基环己胺、三亚乙基二胺、二甲基乙醇胺等主要促进异氰酸酯与水之间生成聚脲和CO2的发泡反应，而对凝胶反应的促进作用较弱。为了调节发泡与凝胶之间的平衡，可以配合使用三嗪类催化剂、碱金属盐等凝胶催化剂，改善全水泡沫的脆性，增强其对基材的粘结力。 1－B8433  2－B8462  3－AK8805  4－L6900 图5  表面活性剂品种和用量对泡沫导热系数的影响 1－低温(－25℃24h)尺寸稳定性    2－高温(80℃24h)尺寸稳定性  图6  泡沫稳定剂B8433用量对泡沫尺寸稳定性的影响  3  全水发泡硬质聚氨酯泡沫塑料 3.1  全水发泡泡沫原液多元醇组分的理化性能指标 全水发泡泡沫原液组合聚醚的理化性能指标见表3。 表3  全水发泡泡沫原液组合聚醚的理化性能指标 牌号 JDPU303 外观 棕色 羟值/mgKOH·g－1 40030 酸值/mgKOH·g－1 ≤0.5 水分/％ 3.50.5 粘度(25℃)/mPa·s 1100300 pH值 9～11     将组合聚醚JDPU303和多异氰酸酯组分混合、搅拌，立即倒入模具使其自由发泡，待泡沫完全熟化后测定相关性能。表4列出了自制全水发泡聚氨酯硬泡的性能以及有关汽车行业、建筑行业(B类)用硬质聚氨酯泡沫塑料的性能指标。可以看出自制全水发泡聚氨酯泡沫的各项性能指标均已达到或超过有关标准中对汽车、建筑行业用CFC-11发泡聚氨酯泡沫塑料的性能要求。 表4  自制全水发泡泡沫与汽车行业、建筑行业用CFC-11体系聚氨酯硬泡的性能指标比较 泡沫种类 JDPU303 JDPU303-N 汽车 (FIAT9.55257) 建筑 (GB10800-B类) 密度/kg·m－3 38.8(芯密度) 43.5(整体密度) 45±5 (整体密度) ≥30 压缩强度/kPa 293 317 － ≥100 拉伸强度/kPa 393 521 － － 导热系数/mW·(m·K)－1 25.6 26.4 ≤27 ≤27 吸水率/％ 2.3 3.9 ≤4 ≤4 体积变化率/％         －25℃ 24h 0.2 0.1 <0.2(－20℃ 24h) － 80℃ 24h 0.33 0.6 ＜0.5 ＜5(70℃ 48h) 水平燃烧速率/mm·min－1 － 86 ＜100 － 粘接性 粘接力大于内聚力 粘结力大于内聚力 粘接力大于内聚力 －           注：JDPU303-N为阻燃型全水泡沫。FIAT9.55257是意大利FIATO汽车公司的标准。 4  结束语 全水硬质聚氨酯泡沫塑料，不仅应用于IVECO车身及冷库、屋顶、大棚等建筑物的喷涂，还用于管中管、夹心板材等的生产[5]。全水泡沫的推广应用，可以彻底淘汰消耗臭氧层物质，使聚氨酯工业成为真正清洁、安全、有效的产业，加快我国氟氯烃取代的进程，促进我国聚氨酯工业赶上国际先进水平。 参考文献 1  Roux J D等.HCFC-141b现状及HFCs最新进展. 见:聚氨酯中国'95国际会议 论文 政研论文下载论文大学下载论文大学下载关于长拳的论文浙大论文封面下载 集,41~44 2  李绍雄,刘益军.聚氨酯树脂及其应用,183~191 3  Fishback T L, etc. Polyol Composition Good Flow And Water Blown Rigid Polyurethane Foams Made Thereby Having Good Dimensional Stability. USP 5686500(1997) 4  Rotermund U, etc.降低烃类发泡的硬质聚氨酯泡沫塑料导热性. 见:聚氨酯中国'95国际会议论文集,49~57 5  Kellner J, Evans D, 沈嵘. 聚氨酯预制隔热管的生产技术和用于集中共热管道高质量的聚氨酯泡沫系统.见:中国聚氨酯工业协会第十次年会论文集102~108 Preparation of Water-Blown Rigid Polyurethane Foams Song Congmei  Tong Jun  Luo Zhenyang (Jiangsu Institute of Chemical Industry, Jiangsu Nanjing 210024) Abstract: The water-blown rigid polyurethane foam systems with good flow were prepared. The related factors effecting on the foaming properties are discussed. The rigid foam has good dimensional stability, excellent adhesion and lower thermal conductivity. The properties of the foam can reach or surpass the specification requirement for automobile and construction industry. The water-blown polyurethane system products have good market prospect. Keywords: polyurethane; rigid foam; water-blown; polyether polyol 作者简介： 宋聪梅  高级 工程 路基工程安全技术交底工程项目施工成本控制工程量增项单年度零星工程技术标正投影法基本原理 师，1989年毕业于南京大学化学系，主要从事聚酯、聚醚及聚氨酯材料的研制开发。 Preparation of Water-Blown Rigid Polyurethane Foams Song Congmei  Tong Jun  Luo Zhenyang (Jiangsu Institute of Chemical Industry, Nanjing 210024) Abstract: The water-blown rigid polyurethane foam systems with good flow were prepared. The related factors effecting on the foaming properties are discussed. The rigid foam has good dimensional stability, excellent adhesion and low thermal conductivity. The properties of the foam can reach or surpass the specification requirement for automobile and construction industry. The water-blown polyurethane system products have good market prospect. Keywords: polyurethane; rigid foam; water-blown; polyether polyol Polyurethane rigid foam is a kind important synthetic material having good mechanical properties and chemical resistance and low thermal conductivity, which is a fine insulation material and used to refrigerators, freezers, automotive industry and building. In a move to reduce or eliminate ozone-depleting blowing agents from the manufacture of polyurethane foams, much effort has gone into investigating substitute of chlorofluorocarbons with low or zero ODP, which promote important innovation of polyurethane foam technology. In the PU rigid foam, the main replacements of the widely used blowing agents CFC-11 are HCFC-141b which is the representative blowing agent for HCFC systems, pentane which is the representative for hydrocarbon blowing agent and water blowing agent. In water blowing process, water reaction with isocyanate produce carbon dioxide gas, which is the real blowing agent in the reaction. Carbon dioxide gas is nonpoisonous and its ODP value is zero, so water is one of the most attractive final replacement of CFC-11. 1. EXPERIMENTAL 1.1 Main Materials polyether PE600, self-made; polyether A, Jinling Petrochemical Ltd. Corp. No2 chemical Plant; polyether TNR410, The Third Petrochemical Factory;  catalysts，self-made; foam stabilizers AK-8805, Dearmate Shichuang Chemical Co.,Ltd.; foam stabilizers B-8462、B-8433 etc, TH. Goldschmidt AG; PAPI, Nippon Polyurethane Industry Co., Ltd.  1.2 Equipment and Devices 2.5L multifunction polymerizer; water content analyzer; rotary viscometer；constant temperature water bath；motor stirrer; high pressure spray machine。; 1.3 Process of Handing Foam All components that will not react with each other, for example, polyol, blowing agents, catalysts and water, are weighed and premixed as part A; The isocyanate is regarded as part B. The part B is added in the part A and mixed intensively. The reaction mixture must be poured into the mold before reaching the cream time and can rise freely. After curing, the foams’ properties are obtained by standardized test methods. 1.4 Typical Formula Polyol competent 100; blowing agents 1.5~2.5; catalysts 2.0~5.0; water 3.0~4.0. Isocyanate Index: 1.0~1.1. Process parameter(20℃): cream time  10~20s;  curing time  20~35s. 2 DISCUSSIONS 2.1 Effect of polyether on Properties of PU Rigid Foams In the process of PU rigid foams, polyether or polyester with a variety molecular weigh and functionality react with isocyanate to form polyurethane linkages, which gather to form the PU foam’s soft segment and rigid segment. The polyether is added into polyol composition by the appliances and properties of PU rigid foam, manufacturing process and material price. Using water as a blowing agent has been found problematic. Water does not have the solvency that some CFC’s and HCFC’s possess leading to a poorer flowing liquid reaction mixture. The isocyanate reaction with water rapidly develops much urea linkages so that the foam becomes brittle and has low adhesion to a substrate. Also, carbon dioxide gas blowing the reaction mixture produced form the isocyanate/water reaction tends to diffuse out of the foam cells, leading to foam shrinkage. In an attempt to alleviate these problems, the highly functional low viscosity polyether should be added to a polyol composition. Table 1 shows the effect of a variety polyether on properties of water blown PU rigid foam. Table 1. Effect of a variety polyether on properties of PU rigid foam Polyol composition ? ? ? JDPU303 Main polyether TNR410 Polyether A PE600 Viscosity of polyol composition at 25℃ /mPa·s 1750 2300 1200 Density/kg·m－3 35.8 37.4 38.8 Compressive Strength/kPa 254 256 293 Tensile Strength /kPa 300 323 393 Thermal Conductivity /W·(m·K)－1 0.0258 0.0263 0.0255 Water absorption /％ Out of shape 3.4 2.3 Dimensional stability at high temperature (80℃24h)/％ 0.4 0.4 0.3 Dimensional stability at low temperature (－25℃24h) /％ 0.5 0.3 0.2         Polyol composition ? and ??, which is mainly composed of polyether TNR410 and A, have too highly viscosity to satisfy foam machine at low temperature, further the PU rigid foam made of ? is out of shape after immersed in water. Polyol composition JDPU303 composed of polyether PE600 not only has lower viscosity to attain usual foam machine’s request, but also has good mechanical properties. 2.2 Effect of Isocyanate Index on PU Rigid Foam In the manufacturing of rigid PU foam, additional isocyanate not only reacts with the urethane and the ureas producing allophanates and biurets, but also trimerize with themselve to form polyisocyanate, thereby improving the foam compressive strength and dimensional stability. Fig.1 shows the dependence of the compressive and tensile strength on isocyanate index. Fig.1 Strength vs. NCO index There are a lot of polyurea linkages in the water blown PU rigid foams, which increase foam’s brittleness. As the isocyanate index increases further the foam brittleness increases, thereby the toughness and tensile strength reduce. Fig. 2 shows effect of isocyanate index on properties of water blowing foams. As ioscyanate index increases further the crosslinking density and rigidity of foam increase, so the low or high temperature dimensional stability increases.  1－high temperature(80℃24h)    2－low temperature(－25℃24h) Fig.2 Dimensional stability vs. NCO index 2.3 Effect of Water Content on Properties of Foam More water in polyol composition reaction with isocyanate develops a higher exotherm, leading to the lower foam density, which affects the properties of rigid foam. 2.3.1 Effect of Water Content on Dimensional Stability of Foam As water content increases further foam density decreases, and more open-cells are formed, which reduce cell wall strength and improve the diffusion of carbon dioxide gas, leading to foam low dimensional stability.(Fig.3) 1－high temperature(80℃24h)    2－low temperature(－25℃24h) Fig.3 Dimensional stability vs. density 2.3.2 Effect of Water Content on Thermal Conductivity of Foam The thermal conductance of the foam is a combination of several factors: thermal conductivity of the cell gas; thermal conductivity of the polymer matrix; convection of the cell gas; thermal radiation. As long as the water blown foam has fine cells, the thermal conductance is primarily due to the first two factors. As the density increases the thermal conductivity of cell struts goes up. This increase, however, is not directly proportional to the increase in density. (Fig.4) Fig.4 Thermal conductivity vs. density 2.4 Effect of Crosslinker on Properties of Foam Crosslinkers are reactive polyfunctional compounds of low molecular weight when used with isocyanates, for example: glycerol, trimethylolpropane, glycol, polyamine and their derivatives. Crosslinkers are added to increase the crosslinking density and close cell content, thereby improving the foam strength and immersion resistance. Table 2 shows the dependence of compressive strength and water adsorption on a variety of crosslinker. Table 2. Effect of crosslinker on properties of PU rigid foam Type Glycerol triethanolamine CLA-1 CLA-2 No Crosslinker Compressive Strength/kPa 253 254 280 293 177 Water absorption /％ Out of shape Out of shape 3.3 2.3 Out of shape             2.5 Selection of Surfactants 2.5.1 Effect of Surfactants on thermal conductivity B8433 is an appropriate silicone-polyether made by TH. Goldschmidt AG for water blown PU rigid foam. Through its good emulsification ability, surfactants accomplish good mixing of polyether composition and isocyanate and strong support of nucleation, resulting in finer, more regular cell structure and low thermal conductivity. Fig.5 shows the dependence of thermal conductivity on type and content of surfactants (based on typical formulation). 2.5.2 Effect of Surfactant Content on Dimensional Stability Surfactant’s performance criteria were the shape of the cup foam, the cell structure, and the appearance of the foam surface. As surfactant content increases the cell structure tends to be more regular and fraction of closed cell increase, which improves foam dimensional stability obviously (Fig. 6) 2.6 Selection of Catalysts In the manufacturing of water blown PU rigid foam the tertiary amines mainly promote the foaming reaction. A triazine catalyst and metal compounds catalyst are applied to promote gel reaction, balance the foaming and gel reaction, thereby improving foam toughness and cohesion. 1－B8433  2－B8462  3－AK8805  4－L6900 Fig.5 Effect of types and content of foam stabilizers on thermal conductivity 1－low temperature(－25℃24h)    2－high temperature(80℃24h)  Fig.6 dimensional stability vs. content of B8433 3. WATER BLOWING PU RIGID FOAM 3.1 Typical Properties of Water Blown Polyol Composition  Table 3. Typical properties of water blown polyol composition Type JDPU303 Appearance Brown Hydroxyl number 40030 Acid number ≤0.5 Water content in (％) 3.50.5 Viscosity @ 25℃ ( mPa·s ) 1100300 pH 9～11     Table 4 shows properties of self-made water blown PU rigid foam and CFC-11 blown PU rigid foam used in automotive industry and building. The properties of the water blown foam can reach or surpass the specification requirement for automobile and construction industry. Table 4. Properties of self-made water blown PU rigid foam and CFC-11 blown PU rigid foam used in automotive industry and building Type JDPU303 JDPU303-N Auto (FIAT9.55257) Building (GB10800-B) Density in kg·m－3 38.8(core density) 43.5 45±5 ≥30 Compressive Strength in kPa 293 317 － ≥100 Tensile Strength in kPa 393 521 － － Thermal Conductivity in mW·(m·K)－1 25.6 26.4 ≤27 ≤27 Water absorption in ％ 2.3 3.9 ≤4 ≤4 Dimensional stability in ％         －25℃ 24h 0.2 0.1 <0.2(－20℃ 24h) － 80℃ 24h 0.33 0.6 ＜0.5 ＜5(70℃ 48h) Horizontal burning speed /mm·min－1 － 86 ＜100 － Cohesiveness adhesion>cohesion adhesion>cohesion adhesion>cohesion －           *  JDPU303-N---flame resistant grade。 4. CONCLUSION In applications where insulating properties are not essential but some structural support is required, a total replacement of CFC-11 by carbon dioxide, which means water, is completely possible. So the water blown PU rigid foam is not only applied to spray on automotive, refrigerated warehouses and house, but also used to manufacture preinsulated pipe and laminated panel. Popularizing of water blown technology will reduce or eliminate ozone-depleting material, make PU industry turn into a really safety, clean production, improve the replacement of chlorofluorocarbons in China. REFERENCES 1 Jean-Denis ROUX etc. Update of HCFC-141b and New Development of HFCs. PU China’95, 41~44 2 Li shaoxiong, Liu yijun, Polyurethane Resin and Its Applicant, 183~191 3 Fishback, Thomas L. etc. Polyol Composition Good Flow And Water Blown Rigid Polyurethane Foams Made Thereby Having Good Dimensional Stability. USP 5686500(1997) 4 U. Rotermund etc. Thermal Conductivity of PU Rigid Foam Reducing Blowing Agents. PU China’95, 49~57 5 Jurgen kellner etc. Manufacture Technology of PU Pre-insulated Pipe and PU Foam System Applied to Central Heat Supply Pipeline. PU China Conference 2000, 102~108 BIOGRAPHY Song Congmei, senior engineer, graduated from Nanjing University in 1989, engaged in development of polyester, polyether and polyurethane material.