Radiation-curable optical fiber coatings having reduced yellowing and fast cure speed

a technology of optical fiber and cure speed, applied in the direction of fibre mechanical structure, coating, transportation and packaging, etc., can solve the problems of inability to cure fast,

Inactive Publication Date: 2001-09-27
DSM NV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0016] about 0.1 wt. % to about 20 wt. % of at least one UV absorbing compound which does not substantially impair the fast cure speed.
[0025] about 0.1 wt. % to about 20 wt. % of at least one UV absorbing compound which does not substantially impair the fast cure speed of the inner or outer primary coating.
[0030] In particular, the outer primary coating compositions of the invention advantageously exhibit good cure speed, and after curing, demonstrate non-yellowing, oxidative stability, good moisture resistance, and tough film properties.

Problems solved by technology

After radiation-cure, this inner primary coating is relatively soft and susceptible to damage.
Also, discoloration is a general problem with urethane acrylate-based compositions, now the industry standard, and tends to be a greater problem with the inner primary rather than outer primary coatings.
Yellowing in either coating, however, is undesirable.
Fiber production is limited by the rate at which the coatings can be sufficiently cured.
That combination of properties, however, can be difficult to achieve.
In addition, coating design is complicated by the effects of the outer primary coating on the cure of the inner primary coating.
These producers demand both fast cure speed and non-yellowing performance from the coating system which prior art coatings do not provide.
UV absorbing compounds ("UV absorbers") have been added to optical fiber coatings, but with mixed results.
It is generally recognized that they slow cure speed.
However, the use of UV absorbing compounds is not taught in these patents.
According to this patent, however, the UV absorbing material is preferably located in the inner primary coating, and is not used in the outer primary coating if a fully-cured outer primary coating is desired.
This patent also does not suggest the preparation of fast cure speed outer primary coatings which reduce yellowing of the inner primary coating through use of a UV absorber.
However, this patent also teaches that increasing the amount of UV absorber will slow cure speed.
Therefore, in general, UV absorbers are considered undesirable when fast cure is essential, and commercial optical fiber coatings today generally do not include them.
These coating systems are inadequate to meet present commercial demands.
Polyester backbones, however, are less preferred because they tend to cause hydrolytic instability.

Method used

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  • Radiation-curable optical fiber coatings having reduced yellowing and fast cure speed
  • Radiation-curable optical fiber coatings having reduced yellowing and fast cure speed
  • Radiation-curable optical fiber coatings having reduced yellowing and fast cure speed

Examples

Experimental program
Comparison scheme
Effect test

example 2

[0173] Formulation of Inner Primary Coatings

[0174] A control inner primary coating composition without UV absorber was formulated from the pre-mixture ingredients summarized in Table II:

2 TABLE II INGREDIENTS AMOUNTS H-(T-PTGL2000).sub.2-T-H.sup.1 50 ethoxylated nonyl phenol acrylate 20.4 lauryl acrylate 7 vinyl caprolactam 6 isobornyl acrylate 13.7 2,4,6-trimethylbenzoyl diphenyl phosphine 1.5 oxide Irganox 1035 0.3 diethyl amine 0.1 mercaptopropyl trimethoxy silane 1.0 .sup.1urethane acrylate oligomer prepared from hydroxyethyl acrylate (H), toluene diisocyanate (T), and a copolymer of THF and methyl-THF having molecular weight of about 2,000 (PTG-L 2,000).

[0175] The control formulation of Table II, which did not comprise UV-absorber, was further formulated into several additional compositions by the addition of additive so that the newly formulated compositions' concentration of additive was 0.5 wt. % (and 99.5 wt. % of composition in Table II).

[0176] The additive for composition...

example 3

[0178] Formulation of Inner Primary Coatings

[0179] Inner primary coatings were formulated according to Table III:

3 TABLE III INGREDIENTS A B H-(I-PTGL2000).sub.2-I-H 51.60 -- H-(I-PPG1025).sub.1.06-(I--- 56 PERMANOLKM10- 1733).sub.1.14-I-H CH.sub.2.dbd.CHCO(OCH.sub.2CH.sub.2).sub.4OC.sub.6 20.87 25.5 H.sub.4C.sub.9H.sub.19 LAURYL ACRYLATE 7.007 -- ISODECYL ACRYLATE -- 14 IRGACURE 1700 -- 3 PHENOXYETHYL ACRYLATE 11.712 -- N-VINYLPYRROLIDONE 4.504 -- IRGACURE 184 3 -- IRGANOX 1035 0.3 0.5 mercaptopropyl 1.001 1.00 trimethoxy silane

[0180] To 99.5% by wt. of each of the above compositions was added 0.5% by wt. SANDOVUR VSU. Film samples were prepared by coating and curing 10 mil films at 1.0 J / cm.sup.2, under a D-lamp (Fusion) in the presence of N.sub.2 and color change was measured at 0, 1, 4, 7, 14 and 28 days. Yellowness Index (YI) was calculated as described below, and delta E values estimated from the yellowness index. The results are provided in FIG. 2. Cured coating compositions ...

example iv

[0182] Cure of Inner Primary Coating Together with Outer Primary Coating Having UV Stabilizer Therein

[0183] Two outer primary coating compositions were formulated from the following pre-mixture ingredients summarized in Table IV:

4 TABLE IV COMPONENTS 4-A 4-B H-T-PTMG650-T-H.sup.1 37.0 37.40 Photomer 3016, 25.0 28.23 bisphenol-A-epoxy diacrylate tetraethyleneglycol diacrylate -- 21.28 triethyleneglycol diacrylate -- 3.45 trimethylolpropane triacrylate -- 6.36 hexanediol diacrylate 10.5 -- isobornyl acrylate 12.0 -- phenoxyethyl acrylate 11.0 -- benzophenone -- 1.49 2,2-dimethoxy-2-phenylacetophenon-e, -- 0.73 Irgacure 651 1-hydroxycyclohexyl phenyl ketone, 1.0 Irgacure 184 2,4,6-trimethylbenzoyl diphenylphosphine 2.0 oxide, Lucirin TPO benzil -- 0.5 diethylamine -- 0.60 phenothiazine -- 0.01 thiodiethylene bis(3,5-di-tert-butyl-4- 0.5 -- hydroxy)hydrocinnamate 2-hydroxy-4-n-octoxybenzophenone -- 0.01 2-hydroxy-4-acryloyloxye-thoxy 0.5 -- benzophenone DC 57, silicone 0.2 0.07 DC 190, ...

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Abstract

Radiation-curable inner and outer primary optical fiber coatings are disclosed having both fast cure speed and reduced rates of yellowing. The compositions comprise particular photoinitiators and UV absorbers which are used in amounts to provide the combination of properties. The UV absorber can have ethylenic unsaturation. Outer primary coatings can be formulated to screen inner primary coatings and have fast cure speed.

Description

[0001] The invention relates to radiation-curable optical fiber coating compositions. In particular, the invention relates to compositions which are both fast-curing and have, upon radiation-cure, reduced rates of yellowing upon accelerated aging.DESCRIPTION OF THE RELATED ART[0002] Optical fibers have become a medium of choice for transmitting information in the modern telecommunications era. Immediately after their manufacture, optical fibers are usually coated with a radiation-curable inner primary coating (or simply "primary coating") which directly contacts the underlying optical fiber. After radiation-cure, this inner primary coating is relatively soft and susceptible to damage. Therefore, the fiber is also usually coated with a radiation-curable outer primary coating (or simply "secondary coating") which overlays the inner primary coating and is stiffer than the soft inner primary coating. This dual coating structure maximizes fiber transmission efficiency and durability and ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C03C25/10C03C25/24C08F2/50G02B6/44C08F220/26C08F290/06C09D4/06
CPCC03C25/106C03C25/1065C09D4/06C08F290/06Y10T428/2938Y10T428/2933Y10T428/31645
Inventor SZUM, DAVID M.CHAWLA, CHANDER P.BISHOP, TIMOTHY E.
Owner DSM NV
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