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EP-4738003-A2 - PHOTOHARDENABLE COMPOSITIONS AND METHODS OF FORMING AN OBJECT

EP4738003A2EP 4738003 A2EP4738003 A2EP 4738003A2EP-4738003-A2

Abstract

The present invention relates to photohardenable compositions for use in forming an object. The photohardenable compositions include a photohardenable resin component, a first photoinitiator that is activatable by exposure to light at a first wavelength and light at a second wavelength, and a second photoinitiator that is activatable by exposure to light at a third wavelength, wherein the first, second, and third wavelengths are not the same, and the third wavelength is shorter than the first wavelength and the second wavelength.

Inventors

  • SANDERS, SAMUEL N.
  • ARNDT, EMILY M.
  • KUMARASAMY, Elango
  • KIEL, Gavin R.

Assignees

  • Quadratic 3D, Inc.

Dates

Publication Date
20260506
Application Date
20230513

Claims (15)

  1. A photohardenable composition comprising a photohardenable resin component, a first photoinitiator, preferably comprising a photoswitchable photoinitiator, that is activatable by exposure to light at a first wavelength and light at a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition or to alter at least one chemical or physical property of the photohardenable composition, and a second photoinitiator comprising a free-radical photoinitiator that is activatable by exposure to light at a third wavelength, wherein the first, second, and third wavelengths are not the same. and the third wavelength is shorter than the first wavelength and the second wavelength.
  2. The photohardenable composition of claim 1 wherein the second photoinitiator comprises a Norrish Type I or a Norrish Type II free-radical photoinitiator.
  3. The photohardenable composition of any one of claims 1-2 further comprising a coinitiator.
  4. The photohardenable composition of claim 3, wherein the coinitiator comprises an iodonium salt in combination with a tertiary amine.
  5. The photohardenable composition of any one of claims 1-4 wherein the second photoinitiator is not activatable by the first wavelength or the second wavelength.
  6. The photohardenable composition of any one of claims 1-5 wherein the first photoinitiator is activatable by exposure to light at a first wavelength and light at a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition, and is included in the photohardenable composition in an amount in a range from 0.0001 to 0.5 weight percent.
  7. The photohardenable composition of any one of claims 1-5 wherein the first photoinitiator is activatable by exposure to light at a first wavelength and light at a second wavelength to alter at least one chemical or physical property of the photohardenable composition, and is included in the photohardenable composition in an amount in a range from about 0.0001 to about 0.009 weight percent.
  8. The photohardenable composition of claim 7 wherein the second photoinitiator is included in the photohardenable composition in an amount in a range from 0.0001 to 1 weight percent.
  9. The photohardenable composition of any one of claims 1-8 wherein the first wavelength is in a range from 300 nm to 550 nm, preferably in a range of from 375 nm to 455 nm.
  10. The photohardenable composition of any one of claims 1-9 wherein the second wavelength is in a range from 450 nm to 700 nm.
  11. The photohardenable composition of any one of claims 1-10 wherein the third wavelength is in a range from 240 nm to 455 nm, preferably in a range from 240 nm to 450 nm.
  12. The photohardenable composition of any one of claims 1-11 wherein the second photoinitiator comprises 1-hydroxycyclohexyl phenyl ketone.
  13. The photohardenable composition of any one of claims 1-12 wherein the photohardenable composition exhibits non-Newtonian rheological behavior.
  14. The photohardenable composition of any one of claims 1-13 wherein the photohardenable composition includes: the first photoinitiator in an amount from about 0.0001 to about 0.1 parts per hundred, the one or more coinitiators in an amount from about 0.001 to about 7.5 parts per hundred, the second photoinitiator in an amount from about 0.0001 to about 10 parts per hundred, and a balance of the photohardenable composition comprising the photohardenable resin component, wherein the balance takes into account amounts of any one or more other optional additives included in the photohardenable composition.
  15. Use of a photohardenable composition of any one of claims 1-14 in printing one or more three dimensional objects in a volume of the photohardenable composition.

Description

CLAIM OF PRIORITY This application claims priority to U.S. Provisional Patent Application No. 63/341,594 filed on May 13, 2022 and U.S. Provisional Patent Application No. 63/438,280 filed on January 11, 2023, each of which is hereby incorporated herein by reference in its entirety for all purposes. TECHNICAL FIELD OF THE INVENTION The present invention relates to the technical field of three-dimensional printing and related compositions, materials, and methods. BRIEF SUMMARY OF THE INVENTION The present invention includes photohardenable compositions and methods for forming an object. Preferred photohardenable compositions and methods include a photohardenable resin component, a first photoinitiator that is activatable by exposure to light at a first wavelength and light at a second wavelength, and a second photoinitiator that is activatable by exposure to light at a third wavelength, wherein the first, second, and third wavelengths are not the same, and the third wavelength is shorter than the first wavelength and the second wavelength. Preferably the second photoinitiator comprises a free-radical photoinitiator. The present invention also includes hardenable resin compositions including a photohardenable resin component, a first photoinitiator that is activatable by exposure to light at a first wavelength and light at a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition, a second photoinitiator that is activatable by exposure to light at a third wavelength, wherein the first, second, and third wavelengths are not the same and the third wavelength is shorter than the first wavelength and the second wavelength, and a resin component that is hardenable by a thermally driven reaction or mechanism, the resin component comprising a monomer, an oligomer, a pre-polymer, a polymer, or a mixture including at least one the foregoing, and methods for forming an object including a hardenable resin composition described herein. Achieving a maximum possible degree of conversion of reactive species to a polymer or cross-linked state in 3D printing is desirable for producing parts (also referred to herein as objects) with reduced leaching of reactive species and/or one or more improved physical properties, such, for example, increased hardness, flexural modulus, tensile strength, scratch resistance, tear resistance, etc. Advantageously, inclusion of a second photoinitiator that is activatable by exposure to light at a third wavelength in a photohardenable composition including photohardenable resin component and a first photoinitiator that is activatable by exposure to light at a first wavelength and light at a second wavelength, in accordance with the present invention, can facilitate achieving a higher degree of conversion without requiring use of the first photoinitiator in amounts for achieving a sufficiently hardened object, which can disadvantageously result in attenuation of the passage of the first wavelength through the photohardenable composition due to increased absorption of first wavelength light by the higher amounts of the first photoinitiator. Such attenuation can result, for example, in non-uniform printing across the volume. Inclusion of a second photoinitiator that is activatable by exposure to light at a third wavelength in a photohardenable resin component in addition to the first photoinitiator, and subsequent exposure of an initial print of an object formed via photoactivation of the first photoinitiator to the third wavelength for activating the second photoinitiator, can facilitate achieving a higher degree of conversion of reactive species to a polymer or cross-linked state in the printed object without increased amount of the first photoinitiator. By including a second photoinitiator with a shorter wavelength of activation than the wavelengths for activating the first photoinitiator, the printing process is not affected by the presence of the second photoinitiator and can facilitate faster and more complete post-cure of the initial print in a post-curing step including exposure to light at a third wavelength. As used herein, "initial print" refers to an object that is not fully hardened that results from selective exposure of the photohardenable composition to the first and second wavelengths. An initial print can preferably have the same shape as, or a shape to be imparted to, the desired object being printed. In accordance with one aspect of the present invention, there is provided a photohardenable composition comprising a photohardenable resin component, a first photoinitiator that is activatable by exposure to light at a first wavelength and light at a second wavelength to induce a crosslinking or polymerization reaction in the photohardenable composition, and a second photoinitiator that is activatable by exposure to light at a third wavelength, wherein the first, second, and third wavelengths are not the same and the third wavelength i