硅烷改性聚氨酯密封胶从液态到固态的化学反应

发布时间 : 2026-5-13 11:09:13
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(Summary description)Customized SILICONE STRUCTURAL SEALANT from China manufacturer refers to the adhesive with high strength, can bear large load, aging resistance, fatigue resistance and corrosion resistance, and has stable performance within the expected life. It is suitable for bearing the bonding of strong structural parts. Non structural adhesive has low strength and poor durability. It can only be used for bonding, sealing and fixing of ordinary and temporary properties, and cannot be used for structural adhesive bonding. NEUTRAL SILICONE WETHERPROOF SEALANT from China manufacturer is a structural adhesive with waterproof function. Silicone glue refers to the adhesive based on silicone rubber. According to different functions, it can be divided into structural adhesive, potting adhesive, sealant, thermal conductive adhesive, flame retardant adhesive and so on.

硅烷改性聚氨酯密封胶从液态到固态的化学反应

(Summary description)Customized SILICONE STRUCTURAL SEALANT from China manufacturer refers to the adhesive with high strength, can bear large load, aging resistance, fatigue resistance and corrosion resistance, and has stable performance within the expected life. It is suitable for bearing the bonding of strong structural parts. Non structural adhesive has low strength and poor durability. It can only be used for bonding, sealing and fixing of ordinary and temporary properties, and cannot be used for structural adhesive bonding. NEUTRAL SILICONE WETHERPROOF SEALANT from China manufacturer is a structural adhesive with waterproof function. Silicone glue refers to the adhesive based on silicone rubber. According to different functions, it can be divided into structural adhesive, potting adhesive, sealant, thermal conductive adhesive, flame retardant adhesive and so on.

发布时间 : 2026-5-13 11:09:13
Views:

硅烷改性聚氨酯密封胶从液态到固态的化学反应过程(见图2-2为:在催化剂(cat)的作用下，链端Si-OR基团首先与空气中的水发生水解反应生成Si-OH，得到的Si-OH再与Si-OR缩合，或两个Si-OH之间缩合形成Si-O-Si键，同时释放出副产物Hz0或CH30H,最后形成以Si-O-Si键为网络交联点，交联点之间为柔性的氧化丙烯聚醚链段的交联结构。密封胶固化过程中，首先是外层与空气接触的Si-OR基团与水汽进行水解缩合反应，形成化学交联，达到无胶粘附在手指上，这个过程即是胶的表干过程，经历的时间即为表干时间。

催化剂用量对硅烷改性聚氨酯密封胶表干时间的影响如图2-3所示。从图可以看出，随着DBT用量的增加，表干时间缩短;相比于不加催化剂的表干时间(大于Sd>，添加0.5%的DBT即可使表干时间缩短至52h;用量增加至1.7%时，表干时间为33h;继续增加用量，表干时间缩短不明显。DBT的催化作用归结于:其能与Si-OR产生配位，使Si-O键极化，从而使带正电荷的Si原子更活泼，更容易受到水分子或Si-OH中氧原子的攻击，加快水解缩合过程。但添加量过多时，催化剂残存于胶中，高温时，特别在湿气作用下可能会引起胶的降解，因此，其最佳的用量范围为1.51.9%，以下选用1.7%用量与TMA做对比实验。

TMA表现出比DBT更有效的催化效果。当添加量为0.3%时，表干时间为8h;添加0.7%时，表干时间为2h;相比1.7%的DBT催化时的表干时间(33h)缩短了31h。TMA更高的催化效率可能是因为，TMA催化剂不但具有上述二月桂酸二丁基锡的催化作用，同时分子结构中含有具有孤对电子的S原子，孤对电子可与端基Si-OR中亲电性的Si原子形成配位或与其水解产物Si-OH形成氢键络合物，加大S i-0键的极化，从而加快其固化过程。另外，从图2-3可以看出，TMA用量超过0.8%后，表干时间变化较小。实验也发现用量过大会导致固化后的胶条内气泡较多，影响其力学性。因此，其最佳的用量范围能为0.50.8%，以下实验讨论中，TMA用量选为MS树脂质量的0.7%。

在固化反应中，硅烷改性聚氨酯密封胶从液态逐渐变化至橡胶弹性态，其模量随时间的变化可以利用流变仪测量，由此可以研究固化过程的时间特性。0.7%TMA催化时的测试曲线如图2-4所示，作为对比，图中也给出了1.7%DBT催化时的测试结果。http://www.sdyuantai.com/

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