US3635544A
Expired / Lapsed
US
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Photochromic polymer matrix
Assignee: Wyeth Holdings LLC
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Filing: 1968-10-21
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Granted: 1972-01-18
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Expires: 1988-10-21
Abstract
Abstract A fast-acting photochromic filter- i.e., a filter whose optical density in the visible light range of 4,000 to 7,500 Angstromswhich is room temperature stable, that is from at least about 20* C. to 80* C., consists of (1) a solid optically transparent polymeric matrix, (2) essentially free from noncombined or molecular oxygen, and preferably protected from diffusion of atmospheric oxygen, in which is (3) dispersed, in solid solution, at least one light absorbing compound having a polynuclear conjugated condensed aromatic ring structure, whose molecules are capable of assuming a metastable triplet state by a process of intersystem crossing (not necessarily of the moiety which assumes the metastable triplet state) and in the triplet state, because of closer triplet states, has energy absorption bands which occur at lower energies (larger wavelengths) than the singlet-singlet absorption for such molecules. A synergic component may also be used as a physically adjacent moiety or molecule in which intersystem crossing occurs more readily than in the light absorbing compound, and which transfers triplet energy to the photochromic moiety. The absorption of singlet-singlet activating energy can be in the synergistic moiety, for single energy transfer, or in the photochromic moiety itself, with transfer of the singlet energy to the synergic moiety, intersystem crossing therein, to triplet energy, and transfer back of the triplet energy to the photochromic moiety, or double energy transfer. Two or more photochromic compounds, with different absorption spectra block ''''windows'''' to give absorption over a desired range. Protective glass layers on each side of a photochromic matrix give physical protection, exclude oxygen, and may also be filters for desired ultraviolet and infrared ranges. Polymerization by ionizing radiation gives freedom from interferrants, such as catalysts residues. Evacuation during processing, or heating in vacuum after formation of the filter aids in removal of uncombined oxygen.
Inventors
- 👤 Robert Franz Stamm
- 👤 Jacob Solomon Brinen
- 👤 Evalyn Hosterman Tennant
- 👤 Frederick Halverson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:36
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/22; G02B5/23; G03; G03C; G03C1/00; G03C1/72; G03C1/73; Y; Y10; Y10S; Y10S428/00; Y10S428/913
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
36 words
A method of preparing a storage stable photochromic filter consisting of preparing a filter as in claim 1 and sealing the same between sheets of glass with a gaseous oxygen excluding seal, thereby excluding atmospheric oxygen.
Claim 2
Independent Claim
231 words
A method of preparing a photochromic filter comprising dissolving in a solvent (a) a polymer substantially free from oxygen and active centers capable of reacting with free radicals and biradicals and which polymer is solid at room temperature, (b) at least one photochromic material, the molecules of which have a polynuclear conjugated condensed aromatic ring system, which system has a set of electronic energy levels such that at least one of said levels is metastable and characterized by having strongly allowed transitions from the metastable level to higher electronic states whose energy spacings relative to the metastable state correspond to energies of photons capable of exciting a visual response in the retina of the human eye, namely whose wavelength is in the range of 4,000 to 7,500 A. units, and which metastable energy level is populated by producing a redistribution of the electrons such that the electronic configuration peculiar to the ground state is altered to the electronic configuration characteristic of the metastable state when the ground-state molecules are subjected to excitation by photons having energies greater than that corresponding to photons having a wavelength of about 6,000 A., (c) casting the solution into the desired shape for the filter, and (d) removing the solvent by evaporation, at least the last portions of the solvent being removed by vacuum and mild heating, thereby simultaneously removing oxygen, thus forming a photochromic filter.
Claim 3
Dependent Claim
36 words
A method of preparing a storage stable photochromic filter consisting of preparing a filter as in claim 3 and sealing the same between sheets of glass with a gaseous oxygen excluding seal, thereby excluding atmospheric oxygen.
Claim 4
Independent Claim
220 words
A method of preparing a photochromic filter comprising (a) dissolving at least one photochromic material in a polymer forming monomer, (b) removing uncombined oxygen by subjecting to vacuum, and (c) while being retained free from uncombined oxygen, (d) subjecting to a polymerizing dose of high-voltage ionizing radiation, and heat, thereby polymerizing substantially all of the monomer, so that the filter is substantially free from uncombined oxygen, and has less than 1.5 percent residual monomer, said photochromic material having molecules which have a polynuclear conjugated condensed aromatic ring system, which system has a set of electronic energy levels such that at least one of said levels is metastable and characterized by having strongly allowed transitions from the metastable level to higher electronic states whose energy spacings relative to the metasTable state correspond to energies of photons capable of exciting a visual response in the retina of the human eye, namely whose wavelength is in the range of 4,000 to 7,500 A. units, and which metastable energy level is populated by producing a redistribution of the electrons such that the electronic configuration peculiar to the ground-state is altered to the electronic configuration characteristic of the metastable state when the ground-state molecules are subjected to excitation by photons having energies greater than that corresponding to photons having a wavelength of about 6,000 A.
Claim 5
Dependent Claim
36 words
A method of preparing a storage stable photochromic filter consisting of preparing a filter as in claim 5 and sealing the same between sheets of glass with a gaseous oxygen excluding seal, thereby excluding atmospheric oxygen.
Claim 6
Dependent Claim
13 words
The method of claim 5 in which the monomer is essentially pure methylmethacrylate.
Claim 7
Dependent Claim
26 words
The method of claim 5 in which the monomer is methylmethacrylate which additionally has present from 1 to 5 percent by weight of ethylene glycol dimethacrylate.
Claim 8
Dependent Claim
262 words
A storage stable photochromic filter effective at room temperature comprising a polymeric material solid at room temperature having dispersed therein at least (I) one photochromic material, the molecules of which have a polynuclear conjugated condensed aromatic ring system, which system has a set of electronic energy levels such that at least one of said levels is metastable and characterized by having strongly allowed transitions from the metastable level to higher electronic states whose energy spacings relative to the metastable state correspond to energies of photons capable of exciting a visual response in the retina of the human eye, namely whose wavelength is in the range of 4,000 to 7,500 A. units, and which metastable energy level is populated by producing a redistribution of the electrons such that the electronic configuration peculiar to the ground state is altered to the electronic configuration characteristic of the metastable state when the ground-state molecules are subjected to excitation by photons having energies greater than that corresponding to photons having a wavelength of about 6,000 A., and said polymeric material additionally having dispersed therein (II) an intensifying synergistic compound having an aromatic ring system, which intensifying compound a. has its lowest excited singlet above the lowest excited singlet level of the photochromic material; b. has its lowest triplet above the lowest triplet of the photochromic material and below the lowest excited singlet of the photochromic material; c. does not fluoresce; and d. has a high rate of crossing, (III) said photochromic material and said synergistic compound being protected from atmospheric oxygen by an uncombined oxygen resistant barrier.
Claim 9
Dependent Claim
32 words
The photochromic filter of claim 9 in which the photochromic material has present at least two photochromic compounds in which absorption windows of one compound are blocked by another photochromic compound present.
Claim 10
Dependent Claim
87 words
A storage stable photochromic filter consisting essentially of three layers, in order from a light source, (A) a glass filter transparent to ultraviolet light and which absorbs in the infrared region; (B) a photochromic filter as defined in claim 9; and (C) a glass filter which is substantially opaque to ultraviolet, deep red, and infrared radiation, and which reduces the intensity of the entire visible spectrum, but has its maximum transmission in the region of 5,400 to 5,500 A., and the human eye is most sensitive. namely
Claim 11
Dependent Claim
210 words
A storage stable photochromic filter effective at room temperature comprising a polymeric material solid at room temperature and having less than about 1.5 percent residual monomer, and being substantially free from uncombined oxygen and active centers capable of reacting with free radicals and biradicals having disperseD therein a photochromic material, the molecules of which have a polynuclear conjugated condensed aromatic ring system, which system has a set of electronic energy levels such that at least one of said levels is metastable an d characterized by having strongly allowed transitions from the metastable level to higher electronic states whose energy spacings relative to the metastable state correspond to energies of photons capable of exciting a visual response in the retina of the human eye, anmely whose wavelength is in the range of 4,000 to 7,500 A. units, and which metastable energy level is populated by producing a redistribution of the electrons such that the electronic configuration peculiar to the ground state is altered to the electronic configuration characteristic of the metastable state when the ground-state molecules are subjected to excitation by photons having energies greater than that corresponding to photons having a wavelength of about 6,000 A., said photochromic material being protected from atmospheric oxygen by an uncombined oxygen resistant barrier.
Claim 12
Dependent Claim
50 words
The photochromic filter of claim 12 in which the photochromic material comprises at least one material having a polynuclear conjugated aromatic system selected from the systems listed in table 1 and table 2, and the polymeric material solid at room temperature is selected from the group listed in table 5.
Claim 13
Dependent Claim
18 words
The photochromic filter of claim 13 in which the photochromic material, at least in part, consists of benzo(a)coronene.
Claim 14
Dependent Claim
85 words
The photochromic filter of claim 12 in which the uncombined oxygen resistant barrier consists of a first layer of glass on one side of the polymer layer which glass is a filter transparent to ultraviolet light and which absorbs in the infrared region, a second layer of glass on the other side which is substantially opaque to at least ultraviolet radiation, and an oxygen resistant seal around the edges of the glass layers to prevent diffusion of oxygen through the edges of the thus-formed filter.
Claim 15
Dependent Claim
57 words
The photochromic filter of claim 15 in which said second layer is a glass filter which is substantially opaque to ultraviolet, deep red, and infrared radiation, and which reduces the intensity of the entire visible spectrum, but has its maximum transmission in the region of 5,400 to 5,500 A., to which the human eye is most sensitive.
Claim 16
Independent Claim
222 words
The method of reactivating a photochromic filter consisting of a. a polymer substantially free from oxygen and active centers capable of reacting with free radicals and biradicals and which polymer is solid at room temperature, b. in which is dissolved in solid solution at least one photochromic material, the molecules of which have a polynuclear conjugated condensed aromatic ring system, which system has a set of electronic energy levels such that at least one of said levels is metastable and characterized by having strongly allowed transitions from the metastable level to higher electronic states whose energy spacings relative to the metastable state correspond to energies of photons capable of exciting a visual response in the retina of the human eye, namely whose wavelength is in the range of 4,000 to 7,500 A. units, and which metastable energy level is populated by producing a redistribution of the electrons such that the electronic configuration peculiar to the ground state is altered to the electronic configuration characteristic of the metastable state when the ground-state molecules are subjected to excitation by photons having energies greater than that corresponding to photons having a wavelength of about 6,000 A., c. and which has been substantially inactivated by atmospheric oxygen diffusing thereinto d. comprising heating under high vacuum until substantially all uncombined oxygen has diffused out of said filter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |