Polymeric rule die, and formulations therefor
Die and counter-die systems, polymeric rule dies for such systems, and polymeric formulations suitable for producing such rule dies using digital rule writing. There is provided a rule die for pressure-contacting of a cardboard workpiece surface, including: (a) a die body; and (b) at least one elongate polymeric rule, each rule having: (i) a first elongate base surface adhesively attached to a surface of the die body; and (ii) an elongate protrusion, distally protruding from the die body, the elongate protrusion having an elongate die surface, the elongate die surface including a polymeric material, the elongate die surface having a contact surface adapted to contact the workpiece surface; the contact surface having a length of at least 5 mm and a first width (W) within a range of 0.4 to 1.0 mm, the rule having a height (H) within a range of 1.0 to 4.5 mm; wherein, over a total length of the contact surface, the contact surface having at most 5 surface pocks/meter, the pocks having a diameter above 0.1 mm.
1. A pre-polymeric formulation for producing a rule die by pressure dispensation via an orifice, the formulation comprising:
(a) at least one pre-polymer;
(b) a photoinitiator selected to polymerize said pre-polymer; and
(c) a thickening agent;
said photoinitiator and said thickening agent being mixed with said pre-polymer, the formulation having the following rheological properties at 25° C.:
(i) G′ rest >3,000 Pascal (Pa);
(ii) G′ exhibits a value of at least 2,500 Pa after being subjected to an oscillation stress of 300 Pa for 20 seconds, within 7 seconds of an abrupt relaxation of said stress,
G′ being a storage modulus of the formulation;
G′ rest being a storage modulus of the formulation at a pressure of 40 Pa, at rest;
said thickening agent including an amorphous silica, a concentration of said amorphous silica within the formulation being within a range of 3% to 32%, by weight;
said pre-polymer comprising at least one monomer or oligomer, said at least one monomer or oligomer having at least one functional moiety selected from the group consisting of acrylic, vinyl, thiol, and epoxy moieties,
wherein, when a cured formulation is obtained by standard curing of the pre-polymeric formulation, said cured formulation has the following strain-stress (ε-σ) properties at 25°C.:
(i) a Young's modulus within a range of 290 to 710 MPa; and
(ii) a strain at break within a range of 13 to 30%.
2. The formulation of claim 1 , said concentration of said amorphous silica within the formulation being within a range of from 5% to 32% by weight.
3. The formulation of claim 1 , said concentration of said amorphous silica within the formulation being within a range of 3% to 23% by weight.
4. The formulation of claim 1 , said concentration of said amorphous silica within the formulation being within a range of 7% to 22%.
5. The formulation of claim 1 , the formulation comprising 6% to 18% tricyclodecane dimethanol diacrylate.
6. The formulation of claim 1 , the formulation comprising 15% to 60% isobornyl acrylate.
7. The formulation of claim 1 , the formulation comprising 5% to 34% of at least one methacrylate.
8. The formulation of claim 1 , the formulation comprising 35% to 88% of at least one methacrylate.
9. A method of writing a pre-polymeric formulation on a substrate, to produce a polymeric rule die, the method comprising:
(a) providing a pre-polymeric formulation in a canister; said formulation comprising:
(i) at least one pre-polymer;
(ii) a photoinitiator selected to polymerize said pre-polymer; and
(iii) a thickening agent;
(b) extruding the formulation from said canister onto the substrate, to form at least one uncured elongate rule; and
(c) curing said uncured elongate rule on the substrate to form the polymeric rule die, the rule die including at least one cured elongate rule having a length of at least 5 mm;
said pre-polymeric formulation in said canister containing a sufficiently low gas concentration, such that over a total length of a contact surface of said cured elongate rule, said contact surface has at most 3 surface pocks/meter, said surface pocks having a diameter above 0.1 mm.
10. The method of claim 9 , wherein, over a total length of said cured elongate rule, a bubble content of bubbles having a diameter above 0.4 mm is at most 2 bubbles/meter.
11. A pre-polymeric formulation for producing a rule die by pressure dispensation via an orifice, the formulation comprising:
(a) at least one pre-polymer;
(b) a photoinitiator selected to polymerize said pre-polymer; and
(c) a thickening agent;
said photoinitiator and said thickening agent being mixed with said pre-polymer, the formulation having the following rheological properties at 25° C.:
(i)G′ rest >3,000 Pascal (Pa);
(ii) G′ exhibits a value of at least 2,500 Pa after being subjected to an oscillation stress of 300 Pa for 20 seconds, within 7 seconds of an abrupt relaxation of said stress,
G′ being a storage modulus of the formulation;
G′ rest being a storage modulus of the formulation at a pressure of 40 Pa, at rest;
said thickening agent including an amorphous silica, a concentration of said amorphous silica within the formulation being within a range of 3% to 32%, by weight;
said monomer or said oligomer having at least one functional moiety selected from the group consisting of acrylic, vinyl, thiol, and epoxy moieties
wherein, when a cured formulation is obtained by standard curing of the formulation, said cured formulation has, at 25° C., a Young's modulus of at least 300 MPa, and a Shore D hardness of at least 55.
12. The pre-polymeric formulation of claim 11 , wherein said Shore D hardness is at least 60.
13. The pre-polymeric formulation of claim 11 , wherein said Shore D hardness is at least 55 and at most 90.
14. The pre-polymeric formulation of claim 12 , wherein said Shore D hardness is at least 55 and at most 88.