Narrow band light absorbing filter

• US 4,601,532 A
• Filed: 05/09/1983
• Issued: 07/22/1986
• Est. Priority Date: 05/09/1983
• Status: Expired due to Fees

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Koelsch, Peter M., Musser, Arlene K.
• Primary Examiner(s): Gron, Teddy S.
• Assistant Examiner(s): Kilby, Catherine S.
• Application Number:
  US06/492,690
• Time in Patent Office: 1,170 Days
• Field of Search: 350/1.1, 350/1.6, 350/311, 252/589
• US Class Current: 359/361
• CPC Class Codes: C08K 5/0041 Optical brightening agents, organic pigments
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 29/14 Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• CPC Class Codes: C08L 61/06 of aldehydes with phenols
• CPC Class Codes: G02B 5/223 containing organic substances, e.g. dyes, inks or pigments

Abstract

An optical transmission radiation filter absorbing between 320 and 500 nm comprises a polymeric film having a benzylidene or naphthalamide dye in combination with a phenol-formaldehyde resin which shifts the absorbing wavelength of the dyes.

Claims

1. An optical transmission filter absorbing radiation between 320 and 500 nm comprising a binder and at least one dye selected from the class of benzylidenes characterized by the fact that the binder comprises sufficient amount of phenol-formaldehyde resin to cause a shift in the spectral absorbance towards the red of said at least one dye.

2. The filter of claim 1 wherein said at least one dye is represented by the formula:

##STR7## wherein R¹ and R² are independently selected from the group consisting of hydrogen, electron-withdrawing groups and ##STR8## with the proviso that no more than one of R¹ and R² may be hydrogen,

R³ and R⁴ are independently selected from electron-withdrawing groups,

R⁵ is selected from the class consisting of hydrogen, methyl and cyano, and

R⁶, R⁷, R⁸, R⁹ and R¹⁰ are independently selected from the group consisting of hydrogen, alkoxy of 1 to 4 carbon atoms, dialkyl amino (with alkyl groups of 1 to 4 carbon atoms), nitro and amido, and one pair of groups adjacent on the benzene ring may comprise the atoms necessary to form a fused benzene ring or 5- or 6-membered heterocyclic ring comprised of only C, S, N and O ring atoms.

3. The filter of claim 2 wherein at least one of R⁶, R⁸ and R¹⁰ are electron-donating groups.

4. The filter of claim 2 wherein R¹ and R² are both strong electron-withdrawing groups selected from the group consisting of CN, CO₂ R wherein R is a hydrocarbon group of 1-12 carbon atoms, SO₂ C₆ H₅ and SO₂ C_x F_2x+1 wherein x is 1 to 8.

5. The filter of claim 3 wherein R¹ and R² are both strong electron-withdrawing groups selected from the group consisting of CN, SO₂ C₆ H₅ and SO₂ C_x F_2x+1 wherein x is 1 to 8.

6. The filter of claim 2 wherein R⁸ comprises a dialkyl amino.

7. The filter of claim 4 wherein R⁸ comprises a dialkyl amino.

8. The filter of claim 2 wherein at least one of R¹ and R² is cyano and the other is an electron-withdrawing group.

9. The filter of claim 3 wherein at least one of R¹ and R² is cyano and the other is an electron-withdrawing group.

10. The filter of claim 6 wherein at least one of R¹ and R² is cyano and the other is an electron-withdrawing group.

11. The filter of claim 2 wherein the phenol-formaldehyde resin comprises from 20 to 100% by weight of the binder.

12. The filter of claim 3 wherein the phenol-formaldehyde resin comprises from 20 to 100% by weight of the binder.

13. The filter of claim 4 wherein the phenol-formaldehyde resin comprises from 20 to 100% by weight of the binder.

14. The filter of claim 5 wherein the phenol-formaldehyde resin comprises from 20 to 100% by weight of the binder.

15. The filter of claim 8 wherein the phenol-formaldehyde resin comprises from 20 to 100% by weight of the binder.

16. The filter of claim 2 wherein said dye has the formula:

##STR9##