Poliuretana elastomer formed by the polymerization reaction of diisocyanate and active hydrogen compound, the rigid segment containing urea group composed of diisocyanate and diamine chain extender, the glass transition temperature is much higher than room temperature, and it is glassy at room temperature. Subcrystals or microcrystals form the plastic phase; flexible segments of polyether or polyester are gathered together to form the matrix or matrix of the poliuretana rubber. Because its glass transition temperature is lower than room temperature, it is called the rubber phase. The microphase separation of the poliuretana elastomer makes the poliuretana elastomer have the advantages of good wear resistance, wide range of hardness, high strength and high elongation, large load supporting capacity, good shock absorption effect and excellent oil resistance. Choosing a suitable molding and processing method can maximize the performance of poliuretana elastomers and prepare various poliuretana elastomers with excellent properties, which are widely used as plastics, rubber, fibers, adhesives and coatings, and even as functional polymer materials. Such as medical poliuretanabahan.
1.1 Prinsip umum untuk memilih kaedah pemprosesan pembentukan
(1) Pengolahan cetakan biasanya untuk mencairkan atau mengubah sebatian polimer dalam keadaan pepejal (serbuk atau berbutir), tampal atau keadaan larutan, dan membentuk bentuk yang diinginkan melalui acuan, dan mempertahankan bentuk yang telah diperoleh, dan akhirnya memperoleh produk. proses membuat kraf.
(2) Aliran pemprosesan pengacuan biasa: â ‘Kaedah membentuk campuran sebatian polimer sekali dan dua kali untuk menghasilkan produk; â € method Kaedah membentuk sebatian polimer untuk menghasilkan produk dalam satu masa; â € ¢ Kaedah menghasilkan produk dari campuran monomer dalam satu langkah â € £ Kaedah pengeluaran satu campuran campuran oligomer.
(3) Prestasi pemrosesan dan faktor-faktor yang mempengaruhi: âKemampuan pemerasan, dalam alat penyemperitan, tong mesin suntikan, penggelek kalender, dan acuan, ketika bahan cacat oleh penyemperitan, bentuk bahan diperoleh dan kemampuan terpelihara. Faktor pembatasnya: kelikatan lebur, struktur peralatan pemprosesan, reologi lebur dan kadar aliran lebur. â € ¡Moldability, dalam proses cetakan di bawah tindakan mesin suntikan, extruder, dan mesin pemampatan, bahan tersebut cacat di bawah tindakan suhu dan tekanan dan keupayaan untuk dicetak dalam acuan. Faktor pembatasnya: reologi, sifat terma dan sifat fizikal dan mekanikal lain dan kereaktifan kimia sebatian polimer. â € ¢ Keterpanjangan, dalam calendering atau peregangan, bahan tersebut cacat dengan calendering atau peregangan dalam satu atau dua arah. Faktor kekangannya: keplastikan bahan dan kesan pengerasan regangan. â € £ Kelenturan, muncung semasa proses penyemperitan, keupayaan bahan untuk membentuk gentian pepejal berterusan melalui pengacuan. Faktor pembatasnya: reologi, kelikatan dan kekuatan lebur, kestabilan terma dan kestabilan kimia.
1.2 Prinsip umum untuk memilih kaedah membentuk dan memproses untukpoliuretanaelastomer
Poliuretana elastomer molding processing system is divided into liquid system and solid system. On the basis of the rapid polymerization reaction of diisocyanate and active hydrogen compound, the molding processing method is conducive to the microphase separation of the poliuretana elastomer. , Liquid system, poliuretana casting glue can be processed by casting (manual casting, centrifugal casting and vacuum casting), reaction injection molding, spraying, knife coating, roller coating, laminating, laminating, bonding, vulcanizing, pasting and rubbing ; Solid system, poliuretana compound rubber can be vulcanized and laminated with mold, poliuretana thermoplastic can be used with thermoplastic, hot injection, calendering, blow molding, spinning and lamination.
1.3 Prinsip pemadanan jenis asas dan kaedah pemprosesan cetakan
Poliuretanaelastomer adalah polimer tinggi antara plastik dan getah dari segi modulus. Ia merangkumi terutamanyapoliuretana compound rubber, poliuretana cast rubber, poliuretana water emulsion and poliuretana thermoplastic. Poliuretana leather, poliuretana adhesives, poliuretana coatings, poliuretana compounds, poliuretana casting glues, poliuretana fibers, poliuretana water emulsions and poliuretana thermoplastics are all derived from the above four types of glue. The molding and processing methods of poliuretana compound rubber, poliuretana water emulsion and poliuretana thermoplastic generally belong to the molding processing methods of rubber, coatings and plastics.
1.4 The use of poliuretana elastomers and the matching principle of production continuity and molding processing methods
Poliuretana elastomer molding and processing methods are matched with the use of poliuretana elastomers, taking into account the continuity of production. For example, poliuretana leather molding methods usually use poliuretana casting adhesive or foaming layer, poliuretana water emulsion and poliuretana thermoplastic as the surface layer; also available Poliuretana thermoplastic and poliuretana water emulsion are used as leather separately, which are based on the basic rubber molding processing method, supplemented by foam molding processing, usually calender molding processing method is selected. Poliuretana paving materials are made of poliuretana casting glue, mainly due to the large product shape and low precision requirements. Medical poliuretana materials have good chemical stability, tissue compatibility, and resistance to biological aging, so the molding process uses dip coating, pouring and coating methods.
