Polyurethan 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 polyurethan rubber. Because its glass transition temperature is lower than room temperature, it is called the rubber phase. The microphase separation of the polyurethan elastomer makes the polyurethan 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 polyurethan elastomers and prepare various polyurethan elastomers with excellent properties, which are widely used as plastics, rubber, fibers, adhesives and coatings, and even as functional polymer materials. Such as medical polyurethanmaterialer.
1.1 Generelle principper for valg af forarbejdningsmetoder
(1) Formbearbejdning er normalt at smelte eller deformere en polymerforbindelse i fast tilstand (pulver eller granulat), pasta eller opløsningstilstand og danne den ønskede form gennem en form og opretholde den opnåede form og til sidst opnå produktet. fremstillingsproces.
(2) Almindelig formbearbejdningsstrøm: “Metoden til dannelse af blandingen af polymerforbindelser én og to gange til fremstilling af produkter; - Metoden til dannelse af polymerforbindelsen til fremstilling af produkter på én gang; â ‘¢ Metoden til fremstilling af produkter fra monomerblandingen i et trin â‘ £ Et-trins produktionsmetode til oligomerblanding.
(3) Forarbejdningsevne og dens påvirkningsfaktorer: â ‘Klembarhed i ekstruderen, injektionsmaskinens tønde, kalenderens ruller og formen, når materialet deformeres ved ekstrudering, opnås materialets form og vedligeholdt evne. Dens restriktive faktorer: smelteviskositet, forarbejdningsudstyrs struktur, smeltereologi og smelteflowhastighed. "Formbarhed, i støbningsprocessen under indsprøjtning af injektionsmaskine, ekstruder og kompressionsmaskine deformeres materialet under påvirkning af temperatur og tryk og evnen til at støbes i formen. Dens restriktive faktorer: reologi, termiske egenskaber og andre fysiske og mekaniske egenskaber og kemisk reaktivitet af polymerforbindelser. â ‘¢ Strækbarhed, ved kalandrering eller strækning, deformeres materialet ved kalandering eller strækning i en eller to retninger. Dens restriktive faktorer: materialets plasticitet og belastningshærdende effekt. â € £ Spinnbarhed, dysen under ekstruderingsstøbning, materialets evne til at danne kontinuerlige faste fibre gennem støbning. Dens restriktive faktorer: reologi, smelteviskositet og styrke, termisk stabilitet og kemisk stabilitet.
1.2 Generelle principper for valg af form- og forarbejdningsmetoder tilpolyurethanelastomerer
Polyurethan 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 polyurethan elastomer. , Liquid system, polyurethan 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, polyurethan compound rubber can be vulcanized and laminated with mold, polyurethan thermoplastic can be used with thermoplastic, hot injection, calendering, blow molding, spinning and lamination.
1.3 Matchningsprincippet for grundlæggende typer og støbemetoder
Polyurethanelastomer er en høj polymer mellem plast og gummi med hensyn til dets modul. Det omfatter hovedsageligtpolyurethan compound rubber, polyurethan cast rubber, polyurethan water emulsion and polyurethan thermoplastic. Polyurethan leather, polyurethan adhesives, polyurethan coatings, polyurethan compounds, polyurethan casting glues, polyurethan fibers, polyurethan water emulsions and polyurethan thermoplastics are all derived from the above four types of glue. The molding and processing methods of polyurethan compound rubber, polyurethan water emulsion and polyurethan thermoplastic generally belong to the molding processing methods of rubber, coatings and plastics.
1.4 The use of polyurethan elastomers and the matching principle of production continuity and molding processing methods
Polyurethan elastomer molding and processing methods are matched with the use of polyurethan elastomers, taking into account the continuity of production. For example, polyurethan leather molding methods usually use polyurethan casting adhesive or foaming layer, polyurethan water emulsion and polyurethan thermoplastic as the surface layer; also available Polyurethan thermoplastic and polyurethan 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. Polyurethan paving materials are made of polyurethan casting glue, mainly due to the large product shape and low precision requirements. Medical polyurethan materials have good chemical stability, tissue compatibility, and resistance to biological aging, so the molding process uses dip coating, pouring and coating methods.
