US2008047668A1PendingUtilityA1
Visibly transparent dyes for through-transmission laser welding
Individually held — no corporate assignee on recordPriority: Nov 10, 2000Filed: Sep 17, 2007Published: Feb 28, 2008
Est. expiryNov 10, 2020(expired)· nominal 20-yr term from priority
B29C 65/1635B29K 2077/00Y10T428/8305B29C 66/71B29K 2033/12B29K 2069/00B29C 66/73921B29C 65/1616C08K 5/0041B29C 65/1674B29K 2995/0026B29C 65/168Y10S428/913B29C 65/1696Y10T428/31504B29C 65/1606B29K 2023/00B29C 65/1683B29K 2067/00
60
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Claims
Abstract
Selection criteria for dyes that predicts efficiency and performance for plastics welding. A first stage quantitative calculation screens dyes that possess an absorption band that can be matched to a laser that is suitable for plastic welding. It also identifies absorption troughs in the visible spectrum and establishes relationships between the relative optical densities of the absorption band and trough. A second stage quantitative calculation screens dyes for their contribution to the transparency of the substrate. By combining these two stages, the usefulness of a candidate dye can be quickly, easily and inexpensively determined.
Claims
exact text as granted — not AI-modified1 . A laser in combination with plastic substrates and an absorber dye for through-transmission laser welding at a welding wavelength comprising:
an upper plastic substrate being highly transmissive of the laser wavelength and having a lower welding surface; a lower substrate with an upper welding surface; an interior joint region being formed by assembling the upper substrate on to the lower substrate with the lower welding surface facing the upper welding surface; an absorber dye disposed in the interior joint region at a concentration and having (i) an absorption band above about 350 nm that includes the welding wavelength, (ii) an absorption trough in the visible spectrum, and (iii) strong transmission of light in the visible spectrum and prior to welding said dye concentration providing a ratio comprising a substrate independent optical density (OD) value within the (ii) absorption trough that is a fraction of the substrate independent optical density (OD) value within the (i) absorption band; and a laser emitting radiation through said upper substrate to said interior joint region where said dye efficiently absorbs the laser radiation to heat said welding surfaces to produce a weld in which the dye that is irradiated within the joint region remains disposed only within the weld and the matching of the absorption band to the welding wavelength is independent of plastic substrate contribution and interference.
2 . The combination of claim 1 , wherein the strong transmission of light is across most of the visible spectrum outside of the absorption band.
3 . The combination of claim 1 , wherein the absorption band is outside the visible spectrum whereby the strong transmission of light is across the entire visible spectrum.
4 . The combination of claim 1 , wherein the strong transmission of light in the visible spectrum comprises a high photopic value for the dye.
5 . The combination of claim 4 , wherein the photopic value of the plastic containing the dye is less than about 10% lower than the photopic value of the plastic, whereby the presence of the dye within the plastic is invisible to the naked eye.
6 . The combination of claim 4 , wherein the photopic value of the plastic containing the dye is within about 10% to about 20% lower than the photopic value of the plastic, whereby the dye lends minimal coloration to the plastic and wherein the plastic containing the dye is transparent.
7 . The combination of claim 6 , wherein the minimal coloration comprises a light pastel coloration.
8 . The combination of claim 1 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is a fraction of the dye's Absorbance Ratio of a wavelength in the absorption band.
9 . The combination of claim 1 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-tenth ( 1/10) of the dye's Absorbance Ratio of a wavelength in the absorption band.
10 . The combination of claim 1 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-hundredth ( 1/100) of the dye's Absorbance Ratio of a wavelength in the absorption band.
11 . The combination of claim 1 , wherein the dye absorbs and transmits heat via vibronic relaxation.
12 . The combination of claim 10 , wherein the strong transmission of light in the visible spectrum comprises a high photopic value for the dye.
13 . The combination of claim 1 , wherein the dye is incorporated into a thin film that is disposed between the lower welding surface and the upper welding surface.
14 . The combination of claim 13 , wherein the film is made of a plastic that is the same as one or both of the substrates.
15 . The combination of claim 13 , wherein the film is on the order of tens of microns thick.
16 . The combination of claim 13 , wherein the film contains on the order of one ten-thousandths part absorber dye on a weight basis.
17 . The combination of claim 1 , wherein the substrate independent optical density (OD) value within the (ii) absorption trough comprises OD(Substrate+Dye@wv)−OD(Substrate@wv).
18 . The combination of claim 1 , wherein the substrate independent optical density (OD) value within the (i) absorption band comprises OD(Substrate+Dye@lww)−OD(Substrate@lww).
19 . The-combination of claim 1 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-thousandth ( 1/1000) of the dye's Absorbance Ratio of a wavelength in the absorption band.
20 . The combination of claim 1 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is a fraction of the dye's Absorbance Ratio of the welding wavelength in the absorption band.
21 . The combination of claim 1 , wherein the absorber dye is incorporated in one of the substrates, and the interior joint region comprises the welding surface.
22 . The combination of claim 21 , wherein the dye is incorporated in one of the welding surfaces by a process selected from the group consisting of insert molding, dip coating, dye infusion, painting, printing, and spraying.
23 . The combination of claim 22 , wherein the dye is incorporated into the entire lower substrate.
24 . The combination of claim 1 , wherein the dye has as Absorption Ratio that yields optical density as a function of wavelength (wv) relative to a reference wavelength, the Absorption Ratio is defined by the following equation
Absorbance
Ratio
(
OD
)
=
OD
(
Substrate
+
Dye
@
wv
)
-
OD
(
Substrate
@
wv
)
OD
(
Substrate
+
Dye
@
lww
)
-
OD
(
Substrate
@
lww
)
where lww is the reference wavelength.
25 . The combination of claim 24 , wherein the reference wavelength is a wavelength above about 350 nm.
26 . The combination of claim 24 , wherein the reference wavelength is a wavelength within the absorption band.
27 . The combination of claim 24 , wherein the reference wavelength is the laser welding wavelength.
28 . A method of through-transmission laser welding with an absorber dye at a laser welding wavelength, comprising the steps of:
providing an upper plastic substrate that is highly transmissive of the laser welding wavelength and which has a lower welding surface, and providing a lower plastic substrate that has an upper welding surface; assembling the upper substrate on to the lower substrate to form an interior joint region that includes the lower welding surface and the facing upper welding surface; incorporating an absorber dye into the interior joint region at a concentration, wherein the absorber dye has (i) an absorption band above about 350 nm that includes the welding wavelength, (ii) an absorption trough in the visible spectrum, and (iii) strong transmission of light in the visible spectrum and prior to welding said dye concentration providing a ratio comprising a substrate independent optical density (OD) value within the (ii) absorption trough that is a fraction of the substrate independent optical density (OD) value within the (i) absorption band; and emitting laser radiation through said upper substrate to said interior joint region where said dye efficiently absorbs the laser radiation to heat said welding surfaces to produce a weld in which the dye that is irradiated within the joint region remains disposed only within the weld and the matching of the absorption band to the welding wavelength is independent of plastic substrate contribution and interference.
29 . The method of claim 28 , wherein the strong transmission of light is across most of the visible spectrum outside of the absorption band.
30 . The method of claim 28 , wherein the absorption band is outside the visible spectrum whereby the strong transmission of light is across the entire visible spectrum.
31 . The method of claim 28 , wherein the strong transmission of light in the visible spectrum comprises a high photopic value for the dye.
32 . The method of claim 31 , wherein the photopic value of the plastic containing the dye is less than about 10% lower than the photopic value of the plastic, whereby the presence of the dye within the plastic is invisible to the naked eye.
33 . The method of claim 31 , wherein the photopic value of the plastic containing the dye is within about 10% to about 20% lower than the photopic value of the plastic, whereby the dye lends minimal coloration to the plastic and wherein the plastic containing the dye is transparent.
34 . The method of claim 33 , wherein the minimal coloration comprises a light pastel coloration.
35 . The method of claim 28 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is a fraction of the dye's Absorbance Ratio of a wavelength in the absorption band.
36 . The method of claim 28 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-tenth ( 1/10) of the dye's Absorbance Ratio of a wavelength in the absorption band.
37 . The method of claim 28 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-hundredth ( 1/100) of the dye's Absorbance Ratio of a wavelength in the absorption band.
38 . The method of claim 28 , wherein the dye absorbs and transmits heat via vibronic relaxation.
39 . The method of claim 37 , wherein the strong transmission of light in the visible spectrum comprises a high photopic value for the dye.
40 . The method of claim 28 , wherein the dye is incorporated into a thin film that is disposed between the lower welding surface and the upper welding surface.
41 . The method of claim 40 , wherein the film is made of a plastic that is the same as one or both of the substrates.
42 . The method of claim 40 , wherein the film is on the order of tens of microns thick.
43 . The method of claim 40 , wherein the film contains on the order of one ten-thousandths part absorber dye on a weight basis.
44 . The method of claim 28 , wherein the substrate independent optical density (OD) value within the (ii) absorption trough comprises OD(Substrate+Dye@wv)−OD(Substrate@wv).
45 . The method of claim 28 , wherein the substrate independent optical density (OD) value within the (i) absorption band comprises OD(Substrate+Dye@lww)−OD(Substrate@lww).
46 . The method of claim 28 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is less than one-thousandth ( 1/1000) of the dye's Absorbance Ratio of a wavelength in the absorption band.
47 . The method of claim 28 , wherein the dye has an Absorption Ratio of a wavelength within the absorption trough that is a fraction of the dye's Absorbance Ratio of the welding wavelength in the absorption band.
48 . The method of claim 28 , wherein the absorber dye is combined with one of the substrates prior to said assembling step.
49 . The method of claim 48 , wherein the dye is incorporated in one of the welding surfaces by a process selected from the group consisting of insert molding, dip coating, dye infusion, painting, printing, and spraying.
50 . The method of claim 49 , wherein the dye is incorporated into the entire lower substrate.
51 . The method of claim 28 , wherein the dye has as Absorption Ratio that yields optical density as a function of wavelength (wv) relative to a reference wavelength, the Absorption Ratio is defined by the following equation
Absorbance
Ratio
(
OD
)
=
OD
(
Substrate
+
Dye
@
wv
)
-
OD
(
Substrate
@
wv
)
OD
(
Substrate
+
Dye
@
lww
)
-
OD
(
Substrate
@
lww
)
where lww is the reference wavelength.
52 . The method of claim 51 , wherein the reference wavelength is a wavelength above about 350 nm.
53 . The method of claim 51 , wherein the reference wavelength is a wavelength within the absorption band.
54 . The method of claim 51 , wherein the reference wavelength is the laser welding wavelength.Join the waitlist — get patent alerts
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