Apparatus for infrared laser spectroscopy of room temperature vulcanizable silicone compositions

Claim 2

Apparatus for determining the concentration of a constituent in a process stream, comprising: (a) means for bypassing a portion of said stream to a sample detection region; (b) means for splitting said portion of said stream into first and second parts and diverting said first part from said sample detection region; (c) a sample cell comprising a pair of opposed infrared transparent windows extending in parallel planes wherein the space between said windows is adjusted upon consideration of the relative viscosity of said second part of said stream; (d) means for diverting said second part of said stream through said sample cell between said windows and wherein the space between said windows defines the thickness of the sample stream flowing therebetween; (e) a laser effective for directing a beam of infrared radiation maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of the constituent in the process stream under consideration through said windows of said cell and said second part of the process stream flowing therebetween; and (f) means for continuously detecting the proportion of said infrared radiation at said predetermined frequency absorbed by said second part of said stream in said sample cell.

Claim 3

Apparatus as in claim 1, wherein the opposed infrared transparent windows are spaced from approximately 0.010 inches to approximately 0.030 inches.

Claim 4

Apparatus as in claims 1 or 2, wherein the laser is operative at a power intensity effective to overcome the characteristic infrared opacity of said sample at a selected thickness and at said selected frequency.

Claim 5

Apparatus for monitoring the crosslinker content of a room temperature vulcanizable silicone composition process stream comprising: (a) means for continuously bypassing a portion of said stream to a sample detection region, dividing said portion into first and second parts, and diverting said first part from said sample detection region; (b) a sample cell comprising a pair of opposed infrared transparent windows extending in parallel planes wherein the space between said windows is adjusted upon consideration of the relative viscosity of said room temperature vulcanizable silicone composition flowing in said process stream; (c) means for diverting said second part through said sample cell between said windows; (d) a laser effective for directing a beam of infrared radiation maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of the crosslinking agent contained in said process stream and at a power intensity effective to overcome the characteristic infrared opacity of said second part of said stream when filling the space between said windows, through said windows of said sample cell and through said second part of the RTV process stream flowing therebetween; and (e) means for continuously detecting the proportion of said infrared radiation when said radiation is absorbed by said second part of said sample cell at said predetermined frequency at said effective intensity.

Claim 6

Apparatus for monitoring the crosslinker content of a room temperature vulcanizable silicone composition process stream comprising: (a) means for continuously bypassing a portion of said stream to a sample detection region, dividing said portion into first and second parts, and diverting said first part from said sample detection region; (b) a sample cell comprising a pair of opposed infrared transparent windows extending in parallel planes wherein the space between said windows is adjusted upon consideration of the relative viscosity of said room temperature vulcanizable silicone composition flowing in said process stream; (c) means for diverting said second part through said sample cell between said windows; (d) a laser effective for directing a beam of infrared radiation maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of the crosslinking agent contained in said process stream and at a power intensity effective to overcome the characteristic infrared opacity of said second part of said stream when filling the space between said windows, through said windows of said sample cell and through said second part of the RTV process stream flowing therebetween; and (e) means for continuously detecting the proportion of said infrared radiation when said radiation is absorbed by said second part of said sample cell at said predetermined frequency at said effective intensity.

Claim 7

Apparatus as in claim 4, wherein said infrared transparent windows are spaced from approximately 0.018 inches to approximately 0.024 inches apart.

Claim 8

Apparatus as in claim 4, wherein the constituent to be analyzed is a crosslinking agent for a room temperature vulcanizable silicone composition exhibiting crosslinking functionality of the type selected from the class of silanes and silioxanes consisting of alkoxy functional, acyloxy functional, acetoxy functional, amine functional, amide functional, and ketoximino functional silanes and siloxanes.

Claim 9

Apparatus as in claim 4, wherein the room temperature vulcanizable silicone composition in the process stream exhibits a viscosity of approximately 300,000 centipoise at 25° C. and the constituent to be monitored is a methyltriacetoxy silane crosslinker and wherein the opposed infrared transparent windows are spaced at least 0.018 to 0.024 inches apart and the infrared radiation is maintained at a frequency of approximately in the range of 1775 to 1800 cm -1 and at a power intensity of at least ten milliwatts.

Claim 10

Apparatus as in claim 4, 5, 6 or 7, further comprising means for monitoring the flow rate of said second part of said stream flowing through said sample cell.

Claim 11

Apparatus for continuous analysis and control of a manufacturing process comprising: (a) means for individually containing a plurality of predetermined starting materials; (b) means for regulating the flow of said starting materials into a processor; (c) a conduit for directing a process stream from said processor to a receptacle; (d) means for diverting a sample of said process stream to a sample detection region; (e) means for irradiating said sample with infrared radiation directed through said detection region, wherein said radiation is adjusted to a frequency of infrared absorption corresponding to a characteristic absorption frequency of one of said starting materials, and wherein the power intensity of the radiation is sufficient to overcome the characteristic infrared opacity of said sample at a selected thickness and frequency; (f) a detector for determining infrared radiation absorbed by said sample; (g) means for detecting a continuous flow of said sample through said sample detection region and indicating any deviation from a predetermined flow rate through said region; and (h) a programmable means effective for interpreting absorption data, continuously storing said data, operating a trend recorder and controlling said means for regulating the flow of said starting materials.

Claim 12

Apparatus for continuous analysis and control of a manufacturing process comprising: (a) means for individually containing a plurality of predetermined starting materials; (b) means for regulating the flow of said starting materials into a processor; (c) a conduit for directing a process stream from said processor to a receptacle; (d) means for diverting a sample of said process stream to a sample detection region; (e) means for irradiating said sample with infrared radiation directed through said detection region, wherein said radiation is adjusted to a frequency of infrared absorption corresponding to a characteristic absorption frequency of one of said starting materials, and wherein the power intensity of the radiation is sufficient to overcome the characteristic infrared opacity of said sample at a selected thickness and frequency; (f) a detector for determining infrared radiation absorbed by said sample; (g) means for detecting a continuous flow of said sample through said sample detection region and indicating any deviation from a predetermined flow rate through said region; and (h) a programmable means effective for interpreting absorption data, continuously storing said data, operating a trend recorder and controlling said means for regulating the flow of said starting materials.

Claim 13

Apparatus as in claim 9, wherein the process to be analyzed and controlled is a room temperature vulcanizable silicone manufacturing process exhibiting crosslinking functionality of the type selected from the class of silanes and siloxanes consisting of alkoxy functional, acyloxy functional, acetoxy functional, amine functional, amide functional, and ketoximino functional silanes and siloxanes.

Claim 14

Apparatus as in claim 10, wherein the room temperature vulcanizable silicone composition in the process stream exhibits a viscosity of approximately 300,000 centipoise at 25° C. and the constituent to be monitored is a methyltriacetoxy silane crosslinker and wherein the opposed infrared transparent windows are spaced approximately 0.018 to 0.024 inches apart and the radiation is maintained at a frequency of approximately 1775-1800 cm -1 and at a power intensity of at least ten milliwatts.

Claim 17

A method as in claim 12, wherein the infrared radiation is maintained at a power intensity effective to overcome the characteristic infrared opacity of said sample at said frequency and sample thickness.

Claim 18

A method as in claim 13, wherein the process stream is a room temperature vulcanizable silicone and the constituent under consideration is a methyltriacetoxysilane crosslinker and wherein said infrared transparent windows of said sample cell are adjusted upon consideration of the relative viscosity of the process stream from approximately 0.018 inches to approximately 0.024 inches apart and said infrared radiation is selectively maintainable at a predetermined frequency corresponding to a selected infrared absorption frequency of methyltriacetoxysilane and at a power intensity effective to overcome the characteristic infrared opacity of said RTV process stream at said sample thickness and said selected absorption frequency.

Claim 19

A method as in claim 14, wherein the opposed infrared transparent windows are spaced approximately 0.018 to 0.024 inches apart and the infrared radiation is maintained at a frequency of about 1775-1800 cm -1 and a power intensity of about at least ten milliwatts.

Claim 20

A method as in claim 15, further comprising the step of monitoring the flow rate of said sample stream.

Claim 21

A method as in claim 13, wherein the process stream is a room temperature vulcanizable silicone composition and wherein the concentration to be determined is of a constituent crosslinking agent exhibiting crosslinking functionality of the type selected from the class of silanes and siloxanes consisting of alkoxy functional, acyloxy functional, acetoxy functional, amine functional, amide functional, and ketoximino functional silanes and siloxanes.