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AssigneeMichigan State University
InventorsAlec B. Scranton, Bharath Rangarajan, Lindsay S. Coons
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A novel method for producing thick composite parts based upon photopolymerizable compositions is disclosed. The constituents of the photopolymerizable mixture comprise a monomer or monomers capable of polymerizing by free radical or cationic mechanisms, and a photoinitiator system which possesses an absorbance characteristic which is effectively reduced, or self-eliminating, upon initiation of the polymerization reaction. Parts having thicknesses up to 2 cm and thicker for varying end use applications are made by photopolymerizing such compositions. In addition, using such compositions composite parts can be made using a reinforcement material such as a glass fiber mat present in an amount by weight of from about 5 to about 70%.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized to a polymer and a photoinitiator having a self-eliminating absorbance and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, said monomer not having unduly facile extractable hydrogens so as to adversely affect the photopolymerization and said monomer and polymer having minimal absorbance in the wavelength range where photopolymerization is initiated so that the absorbance of said photoinitiator is allowed to self-eliminate, providing a light source for emitting light in the ultraviolet wavelength range to excite the photoinitiator so as to initiate said photopolymerization, providing a mold having a cavity in the shape of said part and at least one side thereof allowing the light emitted from said light source to penetrate into the cavity of the mold, initiating operation of the light source to cause light to be emitted, filling said mold with said photopolymerizable composition, positioning said mold and said light source such that the light being emitted from said light source penetrates into the cavity of said mold, exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the photoinitiator self-eliminates as the curing proceeds, and removing the part from the mold cavity.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized to a polymer and a photoinitiator having a self-eliminating absorbance and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, providing a light source for emitting light in the ultraviolet wavelength range to excite the photoinitiator so as to initiate said photopolymerization, said photopolymerizable composition and the conditions of photopolymerization being selected such that said photoinitiator, upon being excited in said ultra-violet wavelength range during photopolymerization, sufficiently fragments into fragmented radicals which do not absorb in said ultraviolet wavelength range such that curing throughout the thickness of the part is effected, providing a mold having a cavity in the shape of said part and at least one side thereof allowing the light emitted from said light source to penetrate into the cavity of the mold, initiating operation of the light source to cause light to be emitted, filling said mold with said photopolymerizable composition, positioning said mold and said light source such that the light being emitted from said light source penetrates into the cavity of said mold, exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the photoinitiator self-eliminates as the curing proceeds, and removing the part from the mold cavity.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized to a polymer and a photoinitiator having a self-eliminating absorbance, a chemical structure consisting of at least two aromatic rings providing sufficient .pi. electronic structure to absorb light in the ultraviolet region of the wavelength spectrum, and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, providing a light source for emitting light in the ultraviolet wavelength range to excite the photoinitiator so as to initiate said photopolymerization, said photopolymerizable composition and the conditions of photopolymerization being selected to allow the absorbance of said photoinitiator to self-eliminate, providing a mold having a cavity in the shape of said part and at least one side thereof allowing the light emitted from said light source to penetrate into the cavity of the mold, initiating operation of the light source to cause light to be emitted, filling said mold with said photopolymerizable composition, positioning said mold and said light source such that the light being emitted from said light source penetrates into the cavity of said mold, exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the photoinitiator self-eliminates as the curing proceeds, and removing the part from the mold cavity.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized via cationic polymerization to a polymer and a coinitiator system having a self-eliminating absorbance and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, said coinitiator system being an anthracene photosensitizer and an onium salt, providing a light source for emitting light in a wavelength range to excite the coinitiator system so as to initiate said photopolymerization, said photopolymerizable composition and the conditions of photopolymerization being selected to allow the absorbance to self-eliminate, providing a mold having a cavity in the shape of said part and at least one side thereof allowing the light emitted from said light source to penetrate into the cavity of the mold, initiating operation of the light source to cause light to be emitted, filling said mold with said photopolymerizable composition, positioning said mold and said light source such that the light being emitted from said light source penetrates into the cavity of said mold, exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the coinitiator system self-eliminates as the curing proceeds, and removing the part from the mold cavity.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized to a polymer and a photoinitiator having a self-eliminating absorbance and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, said monomer not having unduly facile extractable hydrogens so as to adversely affect the photopolymerization and said monomer and polymer having minimal absorbance in the wavelength range where photopolymerization is initiated so that the absorbance of said photoinitiator is allowed to self-eliminate, providing a light source for emitting light in the ultraviolet wavelength range to excite the photoinitiator so as to initiate said photopolymerization, providing a mold having a cavity in the shape of said part, filling said mold with said photopolymerizable composition, initiating operation of the light source to cause light to be emitted and to penetrate into the photopolymerizable composition, and exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the photoinitiator self-eliminates as the curing proceeds.
A method for making a part having a defined thickness comprising providing a photopolymerizable composition including at least one monomer to be photopolymerized via cationic polymerization to a polymer and a coinitiator system having a self-eliminating absorbance and present in an amount sufficient to initiate the photopolymerization of the monomer present while allowing the absorbance to self-eliminate, said coinitiator system being an anthracene photosensitizer and an onium salt, providing a light source for emitting light in a wavelength range to excite the coinitiator system so as to initiate said photopolymerization, said photopolymerizable composition and the conditions of photopolymerization being selected to allow the absorbance to self-eliminate, providing said photopolymerizable composition in the shape of said part, initiating operation of the light source to cause light to be emitted and to penetrate into said photopolymerizable composition, and exposing the photopolymerizable composition to the light emitted for a time adequate to cure said composition throughout the thickness of the part being formed as the absorbance of the coinitiator system self-eliminates as the curing proceeds.
Dependencies are inferred from the claim text.