摘要:
Polyurethane prepolymers are described which are prepared from 2,4′-diiso-cyanate diphenylmethane (2,4′-MDI), a polyol component and an aliphatic diisocyanate. These prepolymers can be cured with aliphatic, cycloaliphatic and/or aromatic amines to form a cured urethane elastomer. In comparison to cured urethane elastomers based on monomeric 2,4′-MDI, these prepolymers provide elastomers with extended pour life, i.e. they exhibit a slower rate of viscosity buildup after curative and prepolymer are mixed which results in a reduced propensity to crack during the curing process and gives the opportunity to cast larger parts. In comparison to polyurea/urethanes prepared from cured TDI-prepolymers and which optionally include H12-MDI, the prepolymers of the invention have better health and safety aspects.
摘要:
The present invention relates to polyester polyols with low functionality and a process for their production, to prepolymers prepared from these polyester polyols and a process for their production, and to polyurethanes prepared from these polyester polyols and/or from these prepolymers, and to processes for their production. These polyester polyols are produced in a two-step process. In the second step of this two-step process, one or more cyclic ester monomers is reacted with one or more polyester polyols at low temperatures.
摘要:
The present invention relates to polyester polyols with low functionality and a process for their production, to prepolymers prepared from these polyester polyols and a process for their production, and to polyurethanes prepared from these polyester polyols and/or from these prepolymers, and to processes for their production. These polyester polyols are produced in a two-step process. In the second step of this two-step process, one or more cyclic ester monomers is reacted with one or more polyester polyols at low temperatures,
摘要:
The present invention relates to a process for the preparation of clear, storage-stable isocyanate-terminated prepolymers. These isocyanate-terminated prepolymers are based on hexanediolether carbonate. This invention also relates to the preparation of polyurethanes from these isocyanate-terminated prepolymers.
摘要:
The present invention relates to a method for preparing oligomeric aliphatic diols, polycarbonatediols based thereon and NCO-terminated prepolymers obtainable therefrom. The inventive compounds may find use in the preparation of polyurethanes.
摘要:
The polyester polyols according to the invention with an average equivalent weight in the range from 200 to 4,000, which were prepared by reacting &agr;,&ohgr;-dicarboxylic acids with butane 1,4-diol, hexane 1,6-diol, propane 1,3-diol or pentane 1,5-diol and with polyols having 3 to 6 hydroxyl groups, are used for the preparation of PUR pourable elastomers with improved resistance to hydrolysis.
摘要:
Polyurethane prepolymers are described which are prepared from 2,4′-diiso-cyanate diphenylmethane (2,4′-MDI), a polyol component and an aliphatic diisocyanate. These prepolymers can be cured with aliphatic, cycloaliphatic and/or aromatic amines to form a cured urethane elastomer. In comparison to cured urethane elastomers based on monomeric 2,4′-MDI, these prepolymers provide elastomers with extended pour life, i.e. they exhibit a slower rate of viscosity buildup after curative and prepolymer are mixed which results in a reduced propensity to crack during the curing process and gives the opportunity to cast larger parts. In comparison to polyurea/urethanes prepared from cured TDI-prepolymers and which optionally include H12-MDI, the prepolymers of the invention have better health and safety aspects.
摘要:
Stable NCO prepolymers are produced from polyisocyanates having a melting point greater than 70° C., preferably, naphthalene diisocyanate, having advantageous physical properties. An important feature of the process of the present invention is the rapid cooling of the prepolymer. The process of the present invention may be carried out on a continuous or batch basis. The prepolymers of the present invention are particularly suitable for the production of cast polyurethane elastomers.
摘要:
Polyurethane (PUR) cast elastomers are produced from NCO-functional prepolymers based on 2,4′-MDI satisfying specific compositional requirements and amine-based chain extenders and/or crosslinking agents.