| 摘要 |
A fully curable jettable composition having a viscosity less than 30cps at a temperature within the range of 15-180 ~C, more preferably at a temperature of 15-100 ~C, e.g. 60-80 ~C the composition comprising: (A) at least one low viscosity reactive resin selected from the group consisting of compounds containing an oxetane ring, cycloaliphatic epoxy resins, tetrahydrofurans, hexahydropyrans and mono-functional (meth)acrylates, said resin having a molecular weight of not greater than 300 Daltons, e.g. 250 Daltons or less, and a viscosity at a temperature in the said range of less than 30 cps, e.g. 5 to 15 cps; (B) at least one higher viscosity resin selected from the group consisting of epoxy resins, compounds containing an oxetane ring and acrylates, which resin acts to thicken the low viscosity resin and strengthen a jetted deposit of the composition, the higher viscosity resin having: a viscosity greater than twice that of the low viscosity resin at the said temperature in the range stated above, and a functionality of greater than or equal to 2; (C) at least one curable toughener, preferably having a functionality of at least 2, such as hydroxy, epoxy, acrylic or other reactive functionalised polymer/oligomer (e.g. derived by functionalising poly(tetrahydrofuran), polycaprolactone, polycarbonate diol, or a dendrimeric polyol; (D) at least one initiator for the polymerisation of the resins, and (E) at least one stabiliser for delaying the curing of the resins of the composition; wherein the low viscosity resin is slower to react than the higher viscosity resin and acts to solvate the higher viscosity resin prior to curing and at least partly during curing and wherein at least 30 % of the components A and B are cationically curable resins. The composition can be jetted from piezo electric printing heads under the control of a computer program to form a multi-layered article, e.g. a three dimensional article, in which the adjacent droplets merge and are cured homogeneously together. |
