摘要:
A method whereby the properties, particularly the recrystallisation temperature, of thermoplastic polyurethane elastomers, particularly those suitable for processing by extrusion, are kept constant during continuous manufacture in screw-type extruding machines by continuously adding substantially straight-chain hydroxyl-terminated polyols having a molecular weight of 500 to 5000, organic diisoicyanates and diol and optionally triol chain-lengthening agents having a molecular weight of 62 to 500, the molar ratio of polyols to chain-lengthening agents being 1:1 to 1:5, and by continuous addition of a catalyst, wherein the recrystallisation temperature is set at a value at least 2.degree. C. below the value for the corresponding TPU manufactured without a catalyst, and when the set recrystallisation temperature is exceeded, the amount of continuously supplied catalyst is increased, whereas when the value falls below, the amount is decreased so as to maintain the set value, the resulting elastomers and use thereof for extrusion.
摘要:
A process for the continuous production of a thermoplastic molding composition containing a mixture of a TPU and a thermoplastic (co)polymer is disclosed. The process comprises (i) introducing into an extruder via a first feed point component I) with at least 3% by weight, with respect to component I), of at least one member selected from the group consisting of components A), B) and C), and(ii) metering in the balance of said A), B) and C) into said extruder via one or more subsequent feed points, (iii) extruding components I) and II) under conditions sufficient to cause A), B) and C) reaction to form TPU, and (iv) upon the completion of said reaction, removing the resulting mixture of TPU and (co)polymer from the extruder, wherein component I) comprises 1 to 60% by weight, with respect to the total mixture, of a thermoplastic (co)polymer, and wherein component II) comprises 99 to 40% by weight, with respect to the total mixture, of the polyurethane-forming components including A) an organic diisocyanate, B) a linear polyol having terminal hydroxyl groups and a number average molecular weight of 500 to 5000, and C) a chain extender having a molecular weight of 60 to 500, and wherein the molar ratio of NCO groups in A) to the groups which react with NCO in B) and C) is in the range of 0.9 to 1.2.
摘要:
A thermoplastic composition comprising aliphatic polyurethane is disclosed. The composition is charactrized in having a post weathering yellow value lower than 20 and good hardness and softening temperature values both before and after weatering for 504 hours in accordance with ISO 4892.
摘要:
A process for the continuous production of a thermoplastic molding composition containing a mixture of a TPU and a thermoplastic (co)polymer is disclosed. The process comprises(i) introducing into an extruder via a first feed point component I) with at least 3% by weight, with respect to component I), of at least one member selected from the group consisting of components A), B) and C), and(ii) metering in the balance of said A), B) and C) into said extruder via one or more subsequent feed points,(iii) extruding components I) and II) under conditions sufficient to cause A), B) and C) reaction to form TPU, and(iv) upon the completion of said reaction, removing the resulting mixture of TPU and (co)polymer from the extruder,wherein component I) comprises 1 to 60% by weight, with respect to the total mixture, of a thermoplastic (co)polymer, and wherein component II) comprises 99 to 40% by weight, with respect to the total mixture, of the polyurethane-forming components including A) an organic diisocyanate, B) a linear polyol having terminal hydroxyl groups and a number average molecular weight of 500 to 5000, and C) a chain extender having a molecular weight of 60 to 500, and wherein the molar ratio of NCO groups in A) to the groups which react with NCO in B) and C) is in the range of 0.9 to 1.2.
摘要:
A process for the continuous production of a thermoplastic molding composition containing a mixture of TPU and a (co)polymer is disclosed. The process comprises (a) introducing into an extruder under time and temperature conditions sufficient to bring about the formation of thermoplastic polyurethane a (co)polymer, and polyurethane-forming components comprising A) an organic diisocyanate, B) a linear polyol having terminal hydroxyl groups and a molecular weight of 500 to 5000, and C) a chain extender having a molecular weight of 60 to 500, and upon completing the formation of said polyurethane (b) discharging the resulting TPU/(co)polymer mixture from the extruder. Importantly, the (co)polymer contains a flow enhancer and the molar ratio of the NCO groups in A) to the groups which react with NCO in B) and C) is 0.9 to 1.2.
摘要:
The present invention relates to a multi-stage process for the continuous preparation of thermoplastically processable polyurethanes with improved processing properties based on various polyols.
摘要:
Thermoplastically processable polyurethane elastomers are prepared by A) mixing one or more substantially linear polyols with a diisocyanate, B) reacting the resultant mixture substantially completely in a reactor at temperatures of >100.degree. C. to form a prepolymer, C) mixing the prepolymer with low molecular weight chain extenders, D) applying the reaction mixture prepared in stage C) to a support and allowing the mixture to react thereon to solidification.
摘要:
The invention relates to a multi-step process for the production of melt-processable polyurethanes with improved processing characteristics, particularly improved homogeneity.
摘要:
The invention relates to the continuous production of polyurethane and polyurethane urea prepolymers by reaction of polyisocyanates with isocyanate-reactive compounds in a mixing nozzle.
摘要:
Polyurethane moulding compositions which can be melt processed in the form of sintering powders suitable for the preparation of grained sintered films and which are prepared exclusively from linear aliphatic components are described. The polyol component is composed of 30 to 80 parts by weight of an aliphatic polycarbonate diol with an average molecular weight {overscore (M)}n of 1000 to 2200 and 70 to 20 parts by weight of a polybutane diol adipate and/or a polycaprolactone diol with an average molecular weight {overscore (M)}n of 1000 to 2400. Moreover, the mixture contains 1,6-hexamethylene diisocyanate in an equivalence ratio of 2.3:1.0 to 6.2:1.0, based on the polyol mixture and butane-1,4-diol as chain extender, the equivalence ratio of the butane-1,4-diol based on the poly mixture being 1.3:1.0 to 5.2:1.0.