Polyuretan 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 polyuretan rubber. Because its glass transition temperature is lower than room temperature, it is called the rubber phase. The microphase separation of the polyuretan elastomer makes the polyuretan 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 polyuretan elastomers and prepare various polyuretan elastomers with excellent properties, which are widely used as plastics, rubber, fibers, adhesives and coatings, and even as functional polymer materials. Such as medical polyuretanmaterialer.
1.1 Generelle prinsipper for valg av formingsbehandlingsmetoder
(1) Formingsbehandling er vanligvis å smelte eller deformere en polymerforbindelse i fast tilstand (pulver eller granulat), pasta eller løsningstilstand, og danne ønsket form gjennom en form, og opprettholde formen som er oppnådd, og til slutt oppnå produktet. lagingsprosess.
(2) Vanlig formingsprosess: “Metoden for å danne blandingen av polymerforbindelser én og to ganger for å produsere produkter; "Metoden for å danne polymerforbindelsen for å produsere produkter på en gang; "Metoden for å produsere produkter fra monomerblandingen i ett trinn" £ Ett trinns produksjonsmetode for oligomerblanding.
(3) Prosesseringsevne og dens påvirkningsfaktorer: â 'Klembarhet i ekstruderen, innsprøytningsmaskinens tønne, kalandervalsene og formen, når materialet deformeres ved ekstrudering, oppnås materialets form og opprettholdt evne. Dens restriktive faktorer: smelteviskositet, prosessutstyrs struktur, smeltereologi og smeltehastighet. "Formbarhet, i støpeprosessen under påvirkning av injeksjonsmaskin, ekstruder og komprimeringsmaskin deformeres materialet under påvirkning av temperatur og trykk og evnen til å støpes i formen. Dens restriktive faktorer: reologi, termiske egenskaper og andre fysiske og mekaniske egenskaper og kjemisk reaktivitet av polymerforbindelser. â ¢ Utvidbarhet, ved kalandrering eller strekking, deformeres materialet ved kalandrering eller strekking i en eller to retninger. Dens restriktive faktorer: materialets plastisitet og strekkherdende effekt. â € £ Spinnbarhet, munnstykket under ekstruderingsstøping, materialets evne til å danne kontinuerlige faste fibre gjennom støping. Dens restriktive faktorer: reologi, smelteviskositet og styrke, termisk stabilitet og kjemisk stabilitet.
1.2 Generelle prinsipper for valg av form- og behandlingsmetoder forpolyuretanelastomerer
Polyuretan 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 polyuretan elastomer. , Liquid system, polyuretan 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, polyuretan compound rubber can be vulcanized and laminated with mold, polyuretan thermoplastic can be used with thermoplastic, hot injection, calendering, blow molding, spinning and lamination.
1.3 Matchingsprinsippet for grunnleggende typer og støpemetoder
Polyuretanelastomer er en høy polymer mellom plast og gummi når det gjelder modulen. Det inkluderer hovedsakeligpolyuretan compound rubber, polyuretan cast rubber, polyuretan water emulsion and polyuretan thermoplastic. Polyuretan leather, polyuretan adhesives, polyuretan coatings, polyuretan compounds, polyuretan casting glues, polyuretan fibers, polyuretan water emulsions and polyuretan thermoplastics are all derived from the above four types of glue. The molding and processing methods of polyuretan compound rubber, polyuretan water emulsion and polyuretan thermoplastic generally belong to the molding processing methods of rubber, coatings and plastics.
1.4 The use of polyuretan elastomers and the matching principle of production continuity and molding processing methods
Polyuretan elastomer molding and processing methods are matched with the use of polyuretan elastomers, taking into account the continuity of production. For example, polyuretan leather molding methods usually use polyuretan casting adhesive or foaming layer, polyuretan water emulsion and polyuretan thermoplastic as the surface layer; also available Polyuretan thermoplastic and polyuretan 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. Polyuretan paving materials are made of polyuretan casting glue, mainly due to the large product shape and low precision requirements. Medical polyuretan materials have good chemical stability, tissue compatibility, and resistance to biological aging, so the molding process uses dip coating, pouring and coating methods.
