WO1997019029A1

WO1997019029A1 - Process for forming a cured coating with a color

Info

Publication number: WO1997019029A1
Application number: PCT/NL1996/000460
Authority: WO
Inventors: Miyuki Ishikawa; Yuji Naito; Takashi Ukachi
Original assignee: Dsm N.V.; Japan Synthetic Rubber Co., Ltd.
Priority date: 1995-11-20
Filing date: 1996-11-20
Publication date: 1997-05-29
Also published as: JPH09142889A; AU7590696A

Abstract

A process for strongly adhering a colored layer onto a secondary coating which has been applied to quartz optical fiber. The process comprises irradiating the surface of the secondary cured coating with a light having a wavelength of 200-450 nm at a dose of 50-1,000 mJ/cm2 and forming a cured coating with color on the surface of this secondary coating.

Description

PROCESS FOR FORMING A CURED COATING WITH A COLOR

BACKGROUND OF THE INVENTION

Field of the Invention:

The present invention relates to a process for forming a colored layer on an optical fiber on which a cured coating of a photocurable resin composition has been applied. Description of the Prior Art:

As shown in Figure 1, an optical fiber A generally has a construction consisting of a primary coating 2 of a soft resin around a quartz fiber 1, a secondary coating 3 of a hard resin around the primary coating 2, and a colored coating 4 around secondary coating 3. The primary coating 2 of a soft resin is omitted in some embodiments. As shown in Figure 2, a plurality of optical fibers A are made into a unit (a ribbon assembly) via a matrix material 5 which generally is made from a radiation curable resin composition.

The colored layer 4 is provided over the hard, secondary coating 3 in order to make it easy to identify each optical fiber from others when optical fibers are taken out from the ribbon assembly.

To join an optical fiber with another optical fiber or with equipment, it is necessary to take out an individual optical fiber from an optical fiber ribbon assembly, or a multi-core structure, by removing the matrix material from the colored optical fiber A. In this instance, if the adhesion strength in the interface of the matrix material 5 and the colored layer 4 is larger than the adhesion strength in the interface of the colored layer 4 and the secondary coating 3 of the optical fiber, or if the strength of the colored layer 4 itself is smaller than the adhesion strength in the interface of the matrix material 5 and the colored layer 4, part or all of the colored layer 4 are peeled off from the secondary coating 3 of the optical fiber, making it difficult to identify one optical fiber from other optical fibers. In an attempt for overcoming this problem, a method of reducing the adhesion strength in the interface of the matrix material 5 and the colored layer 4 by adding a silicone releasing agent to either the colored layer 4 or the matrix material 5 has been proposed. However, when the optical fibers made into a ribbon assembly using this method are stored for a long period of time, the silicone releasing agents bleeds out and the target releasability will be lost. Moreover, the addition of a large amount of silicone releasing agent not only decreases curability of the colored coating 4 with UV light, but also reduces the strength of the colored coating material itself.

An object of the present invention is to provide a process for forming a color layer for optical fiber which is strongly adhered to a secondary coating provided on a quartz fiber.

SUMMARY OF THE INVENTION

This object of the present invention is solved in the present invention by a process for the manfacture of a coated optical fiber with a color layer comprising: (i) coating an optical fiber with a radiation curable resin composition,

(ii) irradiating said coating of a radiation curable resin composition (hereinafter referred to from time to time as Composition I) on said substrate to form a cured coating,

(iii) irradiating the surface of this cured coating with a light having a wavelength of about 200-450 nm at a dose of about 50-1,000 mJ/cm², and

(iv) coating a radiation curable coloring composition (hereinafter referred to from time to time as Composition II) on the surface of said cured coating and curing said coloring composition with radiaton.

Because the irradiation-cured color layer for optical fiber produced by means of the present invention is strongly adhered to a secondary coating provided on a quartz fiber, the colored layer is not peeled off from the secondary coating when the matrix material is to be removed from the optical fiber ribbon assembly, so that it is possible to identify individual optical fibers in the ribbon assembly. The strong adhesion in the interface of the two layers obtained by the process of the present invention exhibits excellent reproducibility.

Other objects, features and advantages of the invention will hereinafter become more readily apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows an illustrative cross-sectional view of coating layers provided to an optical fiber.

Figure 2 is an illustrative cross-sectional view of a ribbon assembly, or multi-core structure, of optical fibers.

DETAILED DESCRIPTION OF THE INVENTION

AND PREFERRED EMBODIMENTS

An embodiment of forming the cured coating with color on quartz fiber by means of the process of the present invention will now be described. This embodiment is also the process of producing optical fiber itself and comprises the aforementioned steps (i) to (iv). Specifically, the cured coating produced by irradiation in step (ii) is activated by being irradiated again in step (iii), and Composition IIB is coated on the activated surface of coating and irradiated with light in step (iv).

Composition I is first applied to the quartz fiber in step (i). This Composition I may be applied directly to the quartz fiber as a secondary coating or may be applied over the primary coating which has been previously applied to the quartz fiber.

The primary and secondary coatings can be applied subsequently while first curing the primary coating. In that case, step (i) comprises (ia) coating the pristine optical fiber with a radiation curable primary coating composition, (ib) curing said composition with radiation, preferably UV-light at a dose between 10-1000 J/cm², and (ic) coating said optical fiber with a radiation curable secondary coating composition. The primary and secondary coatings can also be applied "wet on wet", i.e. without first curing the primary coating. In that case, step (i) comprises (ia) coating a pristine optical fiber with a radiation curable primary coating composition and (ib) coating said optical fiber with a radiation curable secondary coating composition.

The quantity of Composition I to be applied should be such that the secondary coating after cure by irradiation has a thickness of about 10-100 μm, preferably of about 15-40 μm.

After the application of Composition I, the coated surface is irradiated in step (ii) with UV light for example from a high pressure mercury lamp or a metal halide lamp, at a dose of about 10-1,000 J/cm² in the first photo-chamber to form a cured secondary coating. The photo-reaction rate of the Composition I in the cured coating thus obtained is about 50% or more, and preferably about 70% or more. Most preferably, the rate is between about 80% and about 100%. The photo-reaction rate is determined by measuring the concentration of ethylenically unsaturated groups by IR spectrum or NMR before and after the step (ii) and calculated according to the following formula.

Eo - El Photo-reaction rate (%) = xlOO

Eo

wherein Eo is the concentration of ethylenically unsaturated groups of Composition I and El is the concentration of ethylenically unsaturated groups after step (ii ) .

After step (ii), the cured coating of Composition I is again irradiated with a light with a wavelength of 200-450 nm in a photo-chamber. A high pressure mercury lamp or a metal halide lamp can for example be used as the light source. It is desirable to eliminate light with wavelength outside the 200-450 nm range which is contained in the spectrum from these light sources by means of spectroscopic filter. In the case where a fiber drawing machine equipped with two or more photo-chambers is used, the cured coating is formed in the first photo-chamber, following which the cured coating is successively irradiated again in the second photo-chamber with a light having a wavelength of 200-450 nm in step (iii). In the case where a fiber drawing machine equipped with one photo-chamber is used, the step (ii) is carried out while the quartz fiber passes through this photo-chamber, the quartz fiber with the cured coating thereon is wound and irradiated again in a photo-chamber to perform the step (iii). This photo-chamber wherein the step (iii) is carried out may be either the same as or different from the photo-chamber used for carrying out the step (ii).

It is desirable that the above second irradiation be carried out under an atmosphere containing oxygen preferably at a concentration of about 0.1-21 mol%. The dose for the second irradiation is about 50-1,000 mJ/cm², preferably about 100-600 mJ/cm², on the cured coated surface.

After the second irradiation, the photocurable coloring composition (Composition II) is successively coated on the surface of the cured coating of Composition I (the secondary coating). The formation of the coating of Composition II may be carried out either continuously after the completion of step (iii) or after a certain period of time, but, preferably, within two days after the completion of step (iii), and more preferably within one hour after the completion of step ( iii ) .

The quantity of Composition II to be applied preferably is suitable to make a cured coating,

(colored layer) with a thickness of about 1-20 μm. Most preferred is a thickness of about 3-8 μm, as the industry standard is about 5 μm.

Thereafter, the Composition II is cured by irradiation in the same manner as the method for curing the coating of Composition I mentioned above, thereby producing a cured colored layer.

A strong adhesion of the colored layer of Composition II to the cured coating of Composition I (the secondary coating) can be ensured by means of this process.

In particular, the peel strength between the secondary coating and the colored layer in the state of the art generally is not very high, i.e. 10-30 g/cm. With the method of the invention it is possible to achieve much higher peel strength without the need for special additives. Thus, the present invention also relates to a coated and colored optical fiber in which the peel strength between the secondary coating and the colored layer is higher than about 70 g/cm both before and after a hot water test as described below. More preferably, the peel strength is higher than about 100 g/cm.

Furthermore, the coated and colored optical fibers are very well suited for use in a ribbon assembly comprising a plurality of coated and colored optical fibers bonded to each other with a matrix material, wherein the peel strength between the secondary coating and the coloring layer is higher than 70 g/cm, and wherein the peel strength between the colored layer and the matrix material is less than 50 g/cm. Preferably, the latter peel strength is less than 30 g/cm. Radiation curable matrix materials can suitable be formulated from components as described for resin Composition IA.

Although there are no specific limitations to Composition I used in the present invention, the photo-curable resin composition in general comprises the following components (A), (B), and (C), which is given as a typical example and hereinafter referred to from time to time as Composition IA. The several components described for use in composition IA can be choosen and formulated to achieve a variety of properties so that the compositions are useful for primary coatings, secondary coatings and for matrix materials. Furthermore, the components are useful to formulate the binder composition for the radiation curable coloring composition. The coating generally comprise:

(A) about 10-80% by weight of a polymer containing an ethylenically unsaturated group and at least one structural unit selected from the following groups (l)-(4), -(R'O)- (l)

wherein R¹ is an alkylene group having 2-6 carbon atoms,

(C-(CH₂)_ro-0- (2

wherein m denotes an integer of 3-10,

-(0-C-R²-C-0-R³)-

(3)

wherein R² and R³ individually represents a divalent organic group having 2-13 carbon atoms, and

-((R -0-)_n-C-0)-

II (4)

0

wherein n is an integer of 1-50 and R⁴ is an alkylene group having 2-6 carbon atoms or a divalent organic group of the following formula (5),

R⁶

I - Q - C - Q -

I I I R⁵ R⁷ R^β

wherein R⁵, R⁶ , R⁷, and R^θ individually represent a hydrogen atom or an alkyl group having 1-8 carbon atoms, and in which Q is a phenyl ring or a hydrogenated phenyl ring.

(B) about 20-90% by weight of a monomer containing an ethylenically unsaturated group and having a molecular weight of 1300 or smaller, and

(C) about 0.1-10% by weight of a photopolymerization initiator, the weight% being related to the total of the composition.

Illustrating the component (A) for Composition IA, given as specific preferred alkylene groups having 2-6 carbon atoms which are represented by R¹ in formula (1) are the structural units shown by the following formulas (6-1) to (6-8).

(CH₂CH₂)- (6-1

—(CH₂CH₂CH₂) (6-2)

CH,

-(CH₂-CH₂)- (6-3)

"" ( CH₂ H₂ H₂CH₂ ) ^*" (6-4

(CH₂-CH)- (6-5)

I CH₂CH₃

CH₃

I -(CH₂CH₂CH₂-CH)- (6-6)

CH₃

-(CH₂CH₂-CH-CH₂)- (6-7)

(CH₂CH CH CH₂CH₂CH )^■

Of these, the structural units (6-1), (6-3),

(6-4), (6-5), and (6-7) are particularly preferred. In the structural unit represented by the formula (2), m is an integer 3-10 and particularly preferably 5.

In the structural unit shown by the formula (3), as the divalent organic groups represented by R² or R³ in formula (3) divalent alkylene groups and arylene groups are preferred. Given as specific examples of R² or R³ are ethylene, propylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, phenylene, diphenylene, methylenebisphenylene, and the like.

Given as specific preferred alkylene groups having 2-6 carbon atoms which are represented by R⁴ in formula (4) are the structural units shown by the above formulas (6-1) to (6-8), preferably the structural units of the above formulas (6-1) and (6-3).

The following groups (6'-l) to (6 '-3) are given as specific examples of the divalent organic group represented by R⁴ of formula (5), in which Q is a phenyl group or a cyclohexyl group

-Q-CH₂-Q- (6'-l)

CH₃

I

-o-c-o- (6'-2)

I CH,

CH,

-o-c-o-

I (6'-3) CH₂

I CH,

Of these groups, the structural units (6 '-2) is particularly preferred, being bisphenol-A or hydrogenated bisphenol-A.

In the structural units shown by the formula (4), preferred integers represented by n is 1-25. The following groups (7-1) to (7-5) are given as specific examples of the ethylenically unsaturated groups contained in the component (A).

CH,=C-

(7-1)

)12

CH, =C—C-0-R^iJ- (7-2)

R¹² 0

o o In the formulas (7-1) to (7-5), R¹² individually represent a hydrogen atom or a methyl group and R¹³ is an alkylene group having 2-9 carbon atoms, and preferably alkylene groups having 2-5 carbon atoms, such as ethylene group, propylene group, tetramethylene group, and pentamethylene group.

Of the above groups (7-1) to (7-5), the group (7-1) containing one ethylenically unsaturated group, (7-2) containing one ethylenically unsaturated group, (7-3) containing two ethylenically unsaturated groups, and (7-4) containing three ethylenically unsaturated groups are preferred, with the groups (7-1) and (7-2) being particularly preferred.

The structural units (1), (2), (3), (4) and the ethylenically unsaturated group which constitute the component (A) are bonded via at least one bond selected from the group consisting of urethane bond, urea bond, amide bond, ester bond, and ether bond.

For reducing the temperature dependence of the Young's modulus of elasticity of the cured products made from Composition IA in the temperature range of -40°C to 60°C and for appropriately maintaining the viscosity of Composition IA, the number average molecular weight of the component (A) is preferably about 1,000 to about 10,000, and more preferably about 1,500 to about 8,000.

The amount of the ethylenically unsaturated group contained in the component (A) is 1-20, preferably 1-10, per molecule. Excellent curability of the composition, and favorable durability and flexibility of the cured products are obtained by keeping the proportion of the ethylenically unsaturated group in the above range.

The polymers illustrated above can be used independently or in combination of two or more as the component (A) .

The proportion of the component (A) in Composition IA is preferably about 10 to about 75% by weight, and more preferably about 30 to about 70% by weight. Excellent coatability and processability of Composition IA, as well as superior flexibility of the cured products, can be achieved by keeping the proportion of the component (A) in this range.

Embodiments of the process for manufacturing the component (A) is now described. <Process 1> A process comprising reacting a diol

(hereinafter referred to as diol (a)) containing at least one structural unites selected from the above formulas (1), (2), (3), and (4), and optionally a diol other than the diol (a), with a diisocyanate compound to produce a polymer bonded by urethane bonds and having isocyanate group, and then reacting the isocyanate group of this polymer with a compound having a hydroxyl group and the ethylenically unsaturated group represented by the formulas (7-1) to (7-5) (such a compound is hereinafter referred to as "specific unsaturated compound" (a)), thereby introducing the ethylenically unsaturated group via the urethane bond. <Process 2>

A process comprising reacting the diol (a), and optionally a combination of the diol (a) and a diol compound other than the diol (a) or a diamine, with a diisocyanate compound to produce a polymer bonded by urethane bonds, and optionally by urea bonds, and having isocyanate group, and then reacting the isocyanate group of this polymer with the specific unsaturated compound (a), thereby introducing the ethylenically unsaturated group via the urethane bond. <Process 3>

A process comprising reacting a diisocyanate compound with the specific unsaturated compound (a) to produce a polymer bonded by urethane bonds and having isocyanate group and ethylenically unsaturated groups, and reacting the isocyanate group of this polymer with the diol (a), and optionally a combination of the diol (a) and at least one compound selected from diol compounds other than the diol (a) and diamines, thereby producing urethane bonds, and optionally urea bonds. <Process 4>

A process comprising reacting the diol (a), and optionally a combination of the diol (a) and at least one compound selected from diol compounds other than the diol (a) and diamines, with a diisocynate compound to produce a polymer having at least two functional groups selected from hydroxyl group, primary amino group, and secondary amino group, and then reacting these functional groups with a compound having carboxy group, epoxy group, or acid halide group and also having the ethylenically unsaturated group represented by the formulas (7-1) to (7-5), thereby producing ester bonds or amide bonds. The products produced by these Processes 1 to 4 are urethane acrylate polymers and suitable for use as the component (A) .

Given as the diols containing the above structural unit (1) are polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyheptamethylene glycol, polyhexamethylene glycol, poly-2-methyltetramethylene glycol, ethylene oxide adduct to bisphenol A, butylene oxide adduct to bisphenol A, ethylene oxide adduct to bisphenol F, butylene oxide adduct to bisphenol F, ethylene oxide adduct to hydrogenated bisphenol A, butylene oxide adduct to hydrogenated bisphenol A, ethylene oxide adduct to hydrogenated bisphenol F, butylene oxide adduct to hydrogenated bisphenol F, and polyether diols obtained by the ring-opening copolymerization of two or more types of ionic-polymerizable cyclic compounds. Examples of the ionic-polymerizable cyclic compound used to produce these polyether diols include cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, tetrahydrofuran, 2-methyltetrahyd ofuran, 3-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, butadiene monoxide, and isoprene monoxide.

It is also possible to use a polyether diol obtained by the ring-opening copolymerization of one of the above-mentioned ionic polymerizable cyclic compounds and a cyclic imine such as ethylene imine or the like, a cyclic lactone such as β-propiolactone, glycolic acid lactide, or the like, or a cyclic siloxane such as dimethylcyclopolysiloxane; or a polyether diol obtained by the ring-opening copolymerization of one of the above-mentioned ionic polymerizable cyclic compounds and an ionic polymerizable cyclic compound other than the above-mentioned ionic polymerizable cyclic compounds, such as 3 ,3-bischloromethyloxetane, styrene oxide, epichlorhydrine, glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, allyl glycidyl carbonate, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidylbenzoate.

Specific examples of the combination of the two or more types of ionic-polymerizable cyclic compounds include tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, and ethylene oxide and butene-1-oxide. The ring-opening copolymers of these two or more ionic-polyme izable cyclic compounds may be randomly bonded. Given as examples of commercial available diols having a polyoxyalkylene structure are PTMG 1000 and PTMG 2000 (Mitsubishi Chemical); PPG 1000, PPG 2000, EXCENOL 2020, EXCENO 1020 (Asahi Oline); PEG 1000, UNISAFE DC 1100, UNISAFE DA 400, UNISAFE DC 1800 (Nippon Oil and Fats Co., Ltd.); PPTG 2000, PPTG 1000, PTG 400, PTGL 2000 (Hodogaya Chemical Co., Ltd.); and PBG 2000A, PBG 2000B (Dai-ichi Kogyo Seiyaku).

Further, given as examples of the diol having the structural unit of formula (2) are polycaprolactone diols obtained by the reaction of ε-caprolactone and a divalent diol, such as ethylene glycol, tetramethylene glycol, 1,6-hexane glycol, neopentylene glycol, or 1,4-butane diol. As examples of the diol having the structural unit of formula (3), polyester diols obtained by the reaction of a polyhydric alcohol, such as ethylene glycol, propylene glycol, tetramethylene glycol, 1 , 6-hexane diol, neopentylene glycol, or 1 , 4-cyclohexane-dimethanol , and a polybasic acid, such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, or sebacic acid, can be given. Commercially available products which can be used include, for example, Nipporane 4060 (Nihon Polyurethane).

As examples of the diol having the structural unit of formula (4), polycarbonate diols and commercially available products, such as DN-980, DN-981, DN-982, DN-983, Nipporane N-982 (Nihon Polyurethane), and PC-8000 (PPG of the US) can be given.

The following compounds can be given as the diol compounds other than the diol (a) used in the Processes 1-4: 1, 4-cyclohexanedimethanol, dimethylol compounds of dicyclopentadiene, tricyclodecanedimethanol , β-methyl-S-valerolactone, polybutadiene with terminal hydroxyl groups, hydrogenated polybutadiene with terminal hydroxyl groups, castor oil-denatured polyol, polydimethylsiloxane with terminal diols, and polydimethylsiloxane carbitol-denatured polyols.

In addition, as examples of the diamine used in the Processes 2-4 above, ethylene diamine, tetramethylene diamine, hexamethylene diamine, paraphenylene diamine, 4 , 4 '-diaminodiphenylmethane, diamines with hetero atoms, and polyether diamines, can be given.

Included in the diisocyanate used in Processes 1-4 are, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1 , 5-naphthalene diisocyanate, p-phenylene diisocyanate, 3,3 '-dimethyl-4 , 4 '-diphenylmethane diisocyanate, 4 , 4 '-diphenylmethane diisocyanate,

3 , 3 '-dimethylphenylene diisocyanate, 4, 4 '-biphenylene diisocyanate, tetramethylenexylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, methylene bis(4-cyclohexylisocyante) , hydrogenated diphenylmethane diisocyanate, 2 , 2 , 4-trimethylhexamethylene diisocyanate, 2 , 5-bis(isocyanatemethyl )-bicyclo[2.2.l]heptane, 2 , 6-bis(isocyanatemethyl)-bicyclo[2.2.1]heptane, bis(2-isocyanate-ethyl ) fumarate,

6-isopropyl-l, 3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, and lysine diisocyanate. Furthermore, (meth)acrylate compounds having hydroxyl group can be included in the specific unsaturated compound (A). Given as examples of such (meth)acrylate compounds having hydroxyl group are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyoctyl (meth)acrylate, pentaerythritol tri(meth)acrylate, glycerine di (meth)acrylate, dipentaerythritolmonohydroxy penta(meth)acrylate, 1, 4-butanediol mono(meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 1 , 6-hexanediol mono(irteth)acrylate, neopentylglycol mono(meth)acrylate, trimethylolpropane di (meth)acrylate, trimethylolethane di ( eth)acrylate, (meth)acrylates represented by the f ol l owing f ormulas ( 8-1 ) or ( 8-2 ) ,

CH₂=C- C-0-CH₂CH₂- ( 0-CCH₂CH₂CH₂CH₂CH₂ ) _n-OH ( 8-2 )

I II II

R¹³0 0

wherein R¹³ is a hydrogen atom or a methyl group and n is an integer from 1-5.

The proportion of component (A) mentioned in the above description is the proportion reduced to dry components. This applies to the proportions of other components.

The component (B) which constitutes a part of composition IA of the present invention functions as a reactive diluent. Either monofunctional or polyfunctional compounds can be used as the component (B). Often, a combination of one or more mono- and polyfunctional components are used. The monofunctional compounds are used as main component when cured materials with a relatively low modulus of elasticity are desired. The modulus of elasticity can be controlled by using polyfunctional compounds in combination with the monofunctional compounds at a suitable ratio. Examples of the monofunctional compounds and the polyfunctional compounds include the following compounds, but are not limited to these, inasmuch as the compounds have a molecular weight of 1,300 or smaller.

Monofunctional compounds: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl ( eth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, octadecyl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl

(meth)acrylate, ethoxydiethylene glycol (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, phenoxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, dicyclopentadienyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, tricyclodecanyl (meth)acrylate, isobomyl (meth)acrylate, bornyl (meth)acrylate, diacetone (meth)acrylamide, isobutoxymethyl (meth)acrylamide, N-vinylpyrrolidone, N-vinylcaprolactum, N-vinylformaldehyde, N,N-dimethyl ( eth)acrylamide, t-octyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate, N,N-diethyl (meth)acrylamide, N,N '-dimethylaminopropyl (meth)acrylamide, (meth)acryloyl morpholine; vinyl ethers such as hydroxybutyl vinyl ether, lauryl vinyl ether , cetyl vinyl ether , and 2-ethylhexyl vinyl ether ; esters of maleic acid; esters of fumaric acid; and compounds represented by the following formulas (9) to

wherein R¹⁴ is a hydrogen atom or a methyl group; R¹⁵ is an alkylene group containing 2 to 6, preferably 2 to 4 carbon atoms; R¹⁶ is a hydrogen atom or an alkyl group containing 1 to 12, preferably 1 to 9, carbon atoms; and q is an integer from 0 to 12, and preferably from 1 to 8.

(10

wherein R¹⁴ is the same as the R¹⁴ of formula (9) ; R¹⁷ is an alkylene group containing 2 to 8, preferably 2 to 5, carbon atoms; and r is an integer from 1 to 8 , and preferably from 1 to 4.

_R18

CH₂= (11)

wherein R¹⁴ and R¹⁷ are the same as the R¹⁴, R¹⁷ in formula (11) ; s is an integer of 1 to 15; and R¹⁸ are individually a hydrogen atom or a methyl group. Commercially available monofunctional compounds are for example: ARONIX M102, Mill, M113, M114, M117 (Toagosei Chemical Industry Co. , Ltd. ) , KAYARAD TC110S, R629, R644 (Nippon Kayaku Co. , Ltd. ) , and V# 3700 (Osaka Organic Chemical Industry, Ltd. ).

As polyfunctional compounds for example can be used: tr imethylolpropane tr i (meth)acrylate, pentaerythritol (meth)acrylate, ethylene glycol di (meth)acrylate, tetraethylene glycol di (meth)acrylate, polyethylene glycol di (meth)acrylate, 1 , 4-butanediol di (meth)acrylate, 1 , 6-hexanediol di (meth)acrylate, neopentyl glycol di (meth)acrylate, trimethylolpropanetrioxyethyl (meth)acrylate, tris (2-hydroxyethyl ) isocyanurate tri(meth)acr late, tris (2-hydroxyethyl ) isocyanurate di (meth)acr late, tricyclodecanedimethanol di (meth)acrylate, and epoxy (meth)acrylate which is an addition compound of (meth)acrylate to diglycidyl ether of bisphenol A. Commercially available polyfunctional compounds: YUPIMER-UV, SA1002, SA2007 (Mitsubishi Chemical Co. , Ltd.), V# 700 (Osaka Organic Chemical Industry Ltd.), KAYARAD R-604, DPCA-20, DPCA-30, DPCA-60, DPCA-120, HX-620, D-310, D-330, (Nippon Kayaku Co., Ltd.), and ARONIX M-210, M-215, M-315, M-325 (Toagosei Chemical Industry Co., Ltd.). It is desirable that Composition IA contains one or more N-vinyllactams such as N-vinylpyrrolidone or N-vinyl-ε-caprolactam. When used, these N-vinyllactams are incorporated in Composition IA in an amount of 3-20% by weight, and preferably 3-15% by weight.

In order to further improve the water resistance, hot water resistance, acid resistance, and alkali resistance of the cured composition and to promote its reliability over a long period of time, it is desirable that Composition IA contain a monomer having an alicyclic structure. Isobomyl (meth)acrylate, dicyclopentenyl (meth)acrylate, tricyclodecanyl (meth)acrylate, cyclohexyl (meth)acrylate, tricyclodecanedimethanol di (meth)acrylate, and the like can be given as examples of the monomer having an alicyclic structure. Of these, isobomyl (meth)acrylate and tricyclodecanedimethanol di (meth)acrylate are particularly preferred.

The component (B) described above in detail is preferably incorporated in Composition IA in an amount of about 20 to about 60% by weight, and preferably about 25 to about 50% by weight. Either a radical photopolymerization initiator and an ionic photopolymerization initiator may be used as the component (C) which makes up the Composition IA. Radical photopolymerization initiators are preferred.

Given as examples of such the radical photopolymerization initiators are 1-hydroxycyclohexyl phenyl ketone, 2 ,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole,

3-methylacetophenone, 4-chlorobenzophenone, 4 , 4 '-dimethoxybenzophenone, 4,4 '-diaminobenzophenone, Michler 's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, l-(4-isopropylphenyl )-2-hydroxy-2-methylpropan-l-one, 2-hydroxy-2-methyl-l-phenylpropan-l-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-methyl-l-[4-(methylthio)phenyl]-2-morpholino-propan-l -one, 2 , 4 , 6-trimethylbenzoyl-diphenylphosphine oxide, bis-(2 , 6-dimethoxybenzoyl )-

2 , 4 , 4-trimethylpentylphosphine oxide, benzophenone, benzoin, benzoin isobutyl ether, benzyl, 2 ,2-dimethoxy-2-phenylacetophenone, fluorenone, 4-chlorobenzophenone, triphenylamine, carbazole, 3-methylacetophenone, acetophenone diethyl ketal, 4 '-isopropyl-2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methylpropiophenone, α,α'-dichloro-4-phenoxyacetophenone, benzyl dimethyl ketal, 2 ,2-diethoxyacetophenone, chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, 3 , 3-dimethyl-4-methoxybenzophenone, and ε-hydroxycyclohexyl phenyl ketone. Further, given as examples of commercially available radical photopolymerization initiators are Irgacure 184, 369, 651, 500, 907 CGI1700, CGI1750, CGI1850, CG24-61 (Ciba Geigy), Lucirin LR8728 (BASF), Darocur 1116, 1173 (Ciba Geigy), and Uvecryl P36 (UCB). As examples of the ionic photopolymerization initiator, 2, 5-diethoxy-4-(p-tol lmercapto)benzene diazonium PF6-, 2 , 4 , 6-trochlorobenzene diazonium PF6-, 4-dimethylaminonaphthalene diazonium PF6-, and cyclopentadienylpherocenium PF6- can be given. A photo-sensitizer may be used together with the photopolymerization initiator, component (C). Given as examples of the photo-sensitizer are triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylamino-benzoate, ethyl 4-dimethylamino-benzoate, isoamyl

4-dimethylaminobenzoate, and commercially available products such as Uvecryl P102, P103, P104, and P105 (manufactured by UCB Co).

The component (C) may be incorporated in Composition IA in an amount of about 0.1-10% by weight, particularly preferably about 0.5-7% by weight. The photo-sensitizer is preferably added in an amount of about 0.01-10 parts by weight for 100 parts by weight of the photopolymerization initiator.

Further, in addition to the above components, polymers or oligomers can be added to Composition IA. Such polymers or oligomers include epoxy resin, polyamide, polyamideimide, polyurethane, polybutadiene, chloroprene, polyether, polyester, pentadiene derivatives, styrene/butadiene/styrene block copolymer, styrene/ethylene/butene/styrene block copolymer , styrene/isoprene/styrene block copolymer, petroleum resin, xylene resin, ketone resin, fluorine-containing oligomer, silicone oligomer, polysulfide oligomer, and the like.

In addition, reactive oligomers prepared by copolymerizing styrene compounds, (meth)acryl compounds, (meth)acryl compounds with an epoxy group, and the like, and introducing an acryloyl group into the copolymer (e.g. AP-2150, B-3000 to B-3006 (Shin-Nakamura Chemical Co.)) may be incorporated in the composition.

Beside the above components, Composition IA may be formulated with various components, as required, such as antioxidants, UV absorbers, photo-stabilizers, silane coupling agents, aging preventives, heat polymerization inhibitors, leveling agents, coloring matters, surface active agents, preservatives, plasticizers, lubricants, solvents, fillers, wettability improvers, and coated surface improvers.

Commercially available antioxidants which can be used are Irganox 1010, 1035, 1076, 1222 (Ciba Geigy), and the like. As UV absorbers Tinuvin-P, 234, 320, 326, 327, 328, 213 (Ciba Geigy), Sumisorb 110, 130, 140, 220, 250, 300, 320, 340, 350, 400 (Sumitomo Chemical Industries Co., Ltd.), and the like are given as examples. Commercially available photo-stabilizers which can be added include Tinuvin 292, 144, 622LD (Ciba Geigy), and Sanol LS770, LS765, LS292, LS2626, LS1114, LS744 (Sankyo Co.). Examples of silane coupling agents which can be given are γ-aminopropyltriethoxy silane, γ-mercaptopropyltrimethoxy silane, γ-methacryloxypropyl-trimethoxy silane, and commercially available products such as SH6062, SZ6030 (Toray-Dow Corning Silicone Co.) and KBE903, KBM803

(Shin-etsu Silicone Co.). Commercially available aging preventives include Antigene W, S, P, 3C, 6C, RD-G, FR, and AW (Sumitomo Chemical Co.). As the leveling agent, dimethylpolysiloxane-polycarbinol graft polymers and commercially available products such as SH190, SH28PA (Toray-Dow Corning Silicone Co.) are given.

As a typical example of Composition IA which has been described above in detail, a series of products commercially available under the trademark of Desolite R3000 (Japan Synthetic Rubber Co., Ltd.) are given.

Although there are no specific limitations to the photocurable coloring composition (Composition II) used in the present invention, the composition comprising the following Component (A'), and/or Component (B'), Component (C'), and Component (D'), is given as a typical example and hereinafter referred to as Composition IIB.

(A') an acrylate polymer preferably comprising the structural unit represented by the formula (1) and an ethylenically unsaturated group, preferably the urethane acrylate polymer prepared by one of the Processes 1-4 described above, or other radiation curable oligomers such as those described above e.g. AP-2150, B-3000 to B-3006.

(B') A reactive diluent, preferably at least one of the multifunctional reactive diluents, as described above.

(C') a photopolymerization initiator, and (D') a coloring matter.

The urethane acrylate polymer (A') belongs to the Component (A) of Composition IA. The polymers for the Component (A) as well as the processes for manufacturing such polymers have already been illustrated in detail. Particularly preferred urethane acrylate polymers are those obtained by the reaction of (a) alkylene oxide adduct to bisphenol A or bisphenol F, (b) a diisocyanate, and (c) a (meth)acrylate containing a hydroxyl group. This type of urethane acrylate polymer is commercially available under the trademarks, for example, of NK Ester U-1301A, U-701A, U-401A, U-601BA, and U-1001BA (manufactured by

Shin-Nakamura Chemical Co.). Other useful acrylate polymers as component (A') are e.g. acrylated epoxies.

The Component (A') is preferably incorporated in Composition IIB in an amount of about 5 to about 80% by weight, and particularly preferably about 5 to about 70% by weight.

The same reactive diluent as used for composition IA as component (B) can be used as component (B') for Composition IIB. In particular it is useful to have at least one multifunctional reactive diluent present in the coloring composition IIB. The component (B') is used preferably in an amount of 5 to about 80 wt.%, more in particular of about 5 to about 60% by weight.

Either component (A') or component (B') should be present in the coloring composition. Preferably, the amount of (A') plus (B') is at least about 50 wt.% of the total coloring composition.

The same photopolymerization initiators as used for Composition IA as Component (C) can be used as Component (C') for Composition IIB. The photo-sensitizers which are mentioned in connection with Composition IA can also be used together with the photopolymerization initiators in Composition IIB.

The Component (C') is used in an amount of about 0.1-20% by weight, particularly preferably about 0.5-10% by weight, in Composition IIB. The photo-sensitizer is preferably added in an amount of 0.01-15 parts by weight for 100 parts by weight of Component (C'). In order to provide for a fast cure, preferably a mixture of more than one photoinitiator and/or sensitizer is used.

Examples of Component (D') used in Composition IIB include, but not limited to, carbon black, titanium oxide, zinc oxide, insoluble azo pigments, condensed azo pigments, and pigments having a polycyclic structure such as Phthalocyanine Blue. The Component (D') is used in an amount of about 0.1-50% by weight, particularly preferably about 1-10% by weight, in Composition IIB.

Beside these components, various resins can be incorporated in Composition IIB. Given as examples of such resins are thermoplastic resins made from an acrylate monomers or polysacharides. These resins are used in an amount of 0-30% by weight, preferably 0-20% by weight, in Composition IIB.

The photocurable coloring compositions (Composition (IIB)) illustrated above are commercially available under the trademarks, for example, of UV-Ink, Best Cure-F series (manufactured by T&K TOKA Co.). Quartz fibers, glass plates, and the like are included in examples of the material on which the cured coating with color is formed by the process of the present invention.

The present invention will be hereinafter described in more detail by way of examples which are given for illustration of the present invention and shall not to be construed as limiting the present invention.

EXAMPLES

Synthetic Example 1 <Synthesis of Component (A)>

31.03 g of isophorone diisocyanate, 0.080 g of dibutyltin laurate, 0.024 g of

2 , 6-di-tert-butyl-p-cresol , and 0.008 g of phenothiazine were placed in a reaction vessel eguipped with a stirrer, and cooled to below 15°C. 21.84 g of hydroxyethyl alcohol was added dropwise to the mixture while stirring and controlling the temperature below

30°C. After the addition, the mixture was reacted for 1 hour at 30°C. The resulting reaction product was reacted with 1.41 g of ethylene glycol at 20-50°C and then with 45.61 g of polytetramethylene glycol having a number average molecular weight of 2,000 at 50-60°C.

The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less, to obtain a urethane acrylate (a-1) with a number average molecular weight of 1,060.

Synthetic Example 2 <Synthesis of Component (A)>

23.06 g of tolylene diisocyante, 0.080 g of dibutyltin laurate, 0.024 g of 2 , 6-di-tert-butyl-p-cresol , and 0.008 g of phenothiazine were placed in a reaction vessel equipped with a stirrer, and cooled to below 15°C. 20.01 g of hydroxyethyl alcohol was added dropwise to the mixture while stirring and controlling the temperature below 30°C. After the addition, the mixture was reacted for 1 hour at 30°C. The resulting reaction product was reacted with 9.17 g of polyethylene oxide addition diol to bisphenol A (a number average molecular weight: 400) at 20-50°C and then with 47.65 g of polytetramethylene glycol having a number average molecular weight of

2.000 at 50-60°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less, to obtain a urethane acrylate (a-2) with a number average molecular weight of 1,160.

Example 1 <Preparation of Composition I>

Composition (I-a) (a photocurable resin composition) was prepared by blending 60 g of urethane acrylate (a-1), 18.1 g of lauryl acrylate, 8.5 g of N-vinyl pyrrolidone, 9.6 g of SA1002 (Mitsubishi Chemical Co.), 3.0 g of Irgacure 184 (Ciba Geigy), 0.3 g of Irganox 1035 (Ciba Geigy), 0.1 g of SH190 (Toray-Dow Corning Silicone Co.), 0.06 g of SH28PA (Toray-Dow Corning Silicone Co.), and 0.3 g of diethylamine.

Example 2 <Preparation of Composition I> Composition (I-b) (a photocurable resin composition) was prepared by blending 58.5 g of urethane acrylate (a-2), 7.8 g of isobomyl acrylate,

9.1 g of N-vinyl pyrrolidone, 12.2 g of Viscoat 700 (an ethoxylated-bisphenol-A-diacrylate of Osaka Organic Chemical Industry, Ltd.), 1.5 g of

2 , 4 , 6-trimethylbenzoyldiphenylphosphine oxide, 0.5 g of Irganox 907 (Ciba Geigy), 0.3 g of Irganox 1035 (same), 0.2 g of Tinuvin 292 (same), 0.1 g of SH190 (Toray-Dow Corning Silicone Co.), and 0.1 g of diethylamine.

Example 3-5 <Preparation of Composition II> The components shown in Table 1 were blended at proportions indicated in Table 1 to produce photocurable coloring compositions (Composition II).

TABLE 1

Component Example Example Example

(parts by weight ) 3 4 5

(a) Component (A ' ) 60 60 30

(b) Acrylate oligomer 30

(c) Polyfunctional 40 40 40 monomer

(d) Component (C ' ) 5 5 5

(e) Coloring agent (1) 6 6

(f) Coloring agent (2) 6

(a) Component (A'): A urethane acrylate polymer having the following chemical formula.

O O O ll II »

CH₂=CHCO- ( CH₂ ) ₂-OCNH- ( CH₂ ) ₆NHC- ( OCH₂CH₂ ) ₁₅

O 0-

( CH₂ ) ₂-OCCH=CH₂

( b ) Acrylate oligomer: An epoxy acrylate resin having the following chemical formula.

n=l~3 (c) Polyfunctional monomer: Neopentyl glycol diacrylate

(d) Component (C'): A photopolymerization initiator having the following chemical formula.

(e) Coloring agent (1): Phthalocyanine Blue ZCA104 (trademark, manufactured by Dainichiseika Colour & Chemicals Manufacturing. Co.). (f) Coloring agent (2): Insoluble azo pigment,

Kamine F5B (trademark, manufactured by Sanyo Shikiso Co. )

Test Example (Procedure 1)

As a photocurable resin composition,

Composition (I-a) was coated on a glass plate to a thickness of 200 μm and cured by irradiation with light at a dose of 500 mJ/cm² from a metal halide lamp in air, to obtain a cured coating.

(Procedure 2)

The glass plate with the cured coating prepared in (Procedure 1) above was allowed to stand in a dark chamber at 23°C ± 2°C for 10 days, followed by irradiation with light at a dose of 100 mJ/cm² from a metal halide lamp in air.

(Procedure 3)

Composition II obtained in Example 3 was coated on the surface of the coating obtained in (Procedure 2) above to a thickness of 10 μm. This coating was cured by irradiation with light at a dose of 500 mJ/cm² from a metal halide lamp in a nitrogen atmosphere, to obtain a cured coating. A force (g/cm) to peel off the colored coating from the underlying coating was measured by the 90° peeling test according to JIS Z0237 at a peeling speed of 50 mm/min. This measurement was carried out using the double-layered coating sample obtained in (Procedure 3) above and a sample obtained by dipping this sample in hot water at 80°C for one week and drying it. The results are shown in Table 2. Test Example 2 A double layered coating sample was prepared in the same manner as in Test Example 1, except that Composition I-b was used instead of Composition I-a in the Procedure 1; the irradiation of the Procedure 2 was carried out in a nitrogen atmosphere containing 0.2% oxygen; and Composition II obtained in Example 4 was used in the Procedure 3. The peeling strength was measured in the same manner as in Test Example 1. The results are shown in Table 2. Test Example 3 A double layered coating sample was prepared in the same manner as in Test Example 1, except that the irradiation of the Procedure 2 was carried out in a nitrogen atmosphere containing 2% oxygen and Composition II obtained in Example 5 was used in the Procedure 3. The peeling strength was measured in the same manner as in Test Example 1. The results are shown in Table 2.

Comparative Test Example 1

A double layered coating sample was prepared in the same manner as in Test Example 1, except that lights having a wavelength of 400 nm and shorter were cut out by causing the light from the metal halide lamp to pass through a spectroscopic filter in the Procedure 2. The peeling strength was measured in the same manner as in Test Example 1. The results are shown in Table 2.

Comparative Test Example 2 A double layered coating sample was prepared in the same manner as in Test Example 1, except that the Procedure 2 was omitted. The peeling strength was measured in the same manner as in Test Example 1. The results are shown in Table 2.

TABLE 2

Peeling (g/cm) strength

After dipping

At room in hot water temperature (80°C) for 1 hour

Test Example 1 Above 150 * 140

Test Example 2 120 120

Test Example 3 140 130

Comparative Test 20 10

Example 1

Comparative Test 30 10

Example 2

* The cured coating with color was broken before the peeling occurred.

The cured coating with color produced by the process of the present invention can strongly adhere with good reproducibility to a radiation-cured coating. The adhesion is not affected by exposure to severe conditions such as dipping in hot water. When produced on a secondary coating which has been provided on quartz fiber, this cured coating with color is so strongly adhered to the secondary coating that there are no risks for the colored coating to be released from each optical fiber when optical fiber unit is disassembled. This makes it easy to identify an optical fiber from other optical fibers.

Claims

CLA IMS

1. Process for the manufacture of a coated optical fiber with a color layer comprising: (i) coating an optical fiber with a radiation curable resin composition.

(ii) irradiating said coating of a radiation curable resin composition on said substrate to form a cured coating, (ϋi) irradiating the surface of this cured coating with a light having a wavelength of about 200-450 nm at a dose of about 50-1,000 mJ/cm², and (iv) coating a radiation curable coloring composition on the surface of said cured coating and curing said coloring composition with irradiation.

2. Process according to claim 1, wherein the coating step (i) comprises (ia) coating a pristine optical fiber with a radiation curable primary coating composition (ib) curing said composition with radiation and (ic) coating said optical fiber with radiation curable secondary coating composition.

3. Process according to claim 1, wherein the coating step (i) comprises (ia) coating a pristine optical fiber with a radiation curable primary coating composition and (ib) coating said optical fiber with a radiation curable secondary coating composition.

4. Process according to any one of claims 1-3 wherein the radiation curable resin composition is irradiated in step (ii) with UV light at a dose of about 10-1000 J/cm².

5. Process according to any one of claims 1-4 wherein the radiation curable coloring composition is irradiated with UV-light at a dose of about 10- 1000 J/cm².

6. Process according to any one of claims 1-5, wherein the quantity of the radiation curable coloring composition applied is suitable to make a cured colored layer with a thickness of about 1- 20μm.

7. Process according to any one of claims 1-6, wherein the dose applied in step (iii) is about 100-600 J/cm².

8. Process according to any one of claims 1-7 wherein the irradiation in step (iii) is carried out under an atmosphere containing oxygen at a concentration of about 0.1-21 mol.%.

9. Process according to any one of claims 1-8 wherein the radiation curable colored composition is applied within two days after the completion of step (iii).

10. Coated and colored optical fiber comprising a secondary coating and a colored layer on top of the secondary coating wherein the peel strength between the secondary coating and the colored layer is higher than 70 g/cm.

11. Optical fiber according to claim 10 wherein the peel strength is higher than 100 g/cm.

12. Ribbon assembly comprising a plurality of coated and colored optical fibers according to any one of claim 10-11, bonded to each other with a matrix material, wherein the peel strength between the colored layer and the matrix material is less than 50 g/cm.

13. Ribbon assembly according to claim 12 wherein the peel strength between the colored layer and the matrix material is less than 30 g/cm.

14. Process, coated and colored optical fiber and ribbon assembly as substantially described in the description, figures and examples.