JP2001089200A - Radiation cure-type material for covering optical fiber and method for curing the same covering material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject covering material as a liquid radiation cure-type resin composition which is well cured even under exposure to low energy radiation and meets the requirements of characteristics as a material for covering optical fibers. SOLUTION: This radiation cure-type material for covering optical fibers comprises a polyalkylene glycol represented by general formula (1) (m is 3 to 6; and n is 6 to 100) and an oligomer obtained by reacting a diisocyanate having two isocyanate groups in one molecule with an acrylic compound represented by formula (2) (R is H or methyl).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-curable optical fiber coating material having excellent curability and a flexible cured film, and a method for curing the same.

[0002]

2. Description of the Related Art There are various types of optical communication fibers such as silica glass, multi-component glass, and plastic, but in reality, their light weight, low loss, Due to its high durability and large transmission capacity, quartz glass-based materials are widely used in a wide range of fields. However, since the silica glass-based fiber is extremely thin and changes may occur due to external factors, the silica glass-based optical communication fiber is a soft liquid curable material that is previously cured on a fused-spun silica glass fiber. After coating and curing with a resin and performing a primary coating, in order to protect the primary coating layer, it is further coated with a hardened liquid curable resin of a cured product, cured, and then subjected to a secondary coating.

[0003] The characteristics required for this primary coating material are that it has a low Young's modulus, a small temperature dependence, and good durability (heat and water resistance) in order to prevent microbend loss due to external stress or temperature change. , Low water absorption, low hydrogen generation, high refractive index, and the properties required for the secondary coating material are sufficient hardness and flexibility, acid, The cured film does not deteriorate even in an alkaline atmosphere and has low water absorption.

Further, in recent years, as the optical fiber drawing speed has been increased in order to improve the productivity, it has been strongly required that both the primary coating material and the secondary coating material be cured with low energy.
To meet these demands, urethane acrylate-based ultraviolet curable resin compositions have been proposed in the past.
-19694, Japanese Patent No. 2522663, Japanese Patent No. 25
As described in JP-A-47021, there is known an ultraviolet liquid curable composition comprising a urethane acrylate oligomer, a reactive monomer, and a polymerization initiator. However, in these compositions, only one acrylic group is introduced at each terminal via a urethane bond at the molecular chain terminal of a linear polyether, polyester, or the like.
Curing at low energy was limited.

US Pat. No. 4,608,409 proposes a polyacrylate oligomer synthesized by the reaction of pentaerythritol triacrylate with an isocyanate at the molecular chain end of a linear polyether.
60% purity of pentaerythritol triacrylate
It is difficult to synthesize a product with a desired structure, and when it has three acrylic groups at the end, it is difficult to obtain a flexible cured film, and it is not suitable as an optical fiber primary coating material. Was something.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a coating material for a radiation-curable optical fiber which is excellent in curability, cures well even with low-energy radiation, and has a cured film with high flexibility. And a method for curing the same.

[0007]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to solve the above problems, and as a result, have found that polyalkylene glycol represented by the following general formula (1) and one molecule A radiation-curable optical fiber coating material comprising an oligomer comprising a reaction product of a diisocyanate having two isocyanate groups therein and an acrylic compound represented by the formula (2) cures well even with low-energy radiation. Coating to a film thickness of 20 to 65 μm and irradiating it with an electron beam accelerated at an accelerating voltage of 150 kV or less at a dose of 3 Mrad or less to effectively cure, and that the cured film is rich in flexibility. Having found this, the present invention has been accomplished.

Accordingly, the present invention provides a method of reacting [I] a polyalkylene glycol represented by the following general formula (1) with a diisocyanate having two isocyanate groups in one molecule and an acrylic compound represented by the following formula (2). to contain oligomer obtained Te radiation curable optical fiber coating material, characterized _{in, HO (C m H 2m O} ) n -H (1) ( wherein, m is 3 to 6, n is 6 to 100 is a _{number.) CH 2 = CRCOOCH 2 CH} (OH) CH 2 OCOCR = CH 2 (2) ( wherein, R represents a hydrogen atom or a methyl group.) [II]
100 parts by weight of the oligomer and 5-20 reactive diluents
The coating material for a radiation-curable optical fiber according to [I], comprising: 0 parts by weight and 0 to 20 parts by weight of a photopolymerization initiator; [III] the coating material according to the above [I] or [II]. A coating material is applied to an optical fiber so as to have a thickness of 20 to 65 μm, and an electron beam accelerated at an acceleration voltage of 150 kV or less is applied to an optical fiber at 3 Mr.
The present invention provides a method for curing a coating material for an optical fiber, characterized in that the coating material is cured by irradiating it with a dose of ad or less.

Hereinafter, the present invention will be described in more detail.
Radiation-curable optical fiber coating material of the present invention is represented by the following general formula _{(1) HO (C m H} 2m O) n -H (1) ( wherein, m is 3 to 6, n is the number of 6 to 100 ), A diisocyanate, and the following formula (2): CH ₂ = CRCOOCH ₂ CH (OH) CH ₂ OCOCR = CH ₂ (2) (wherein R represents a hydrogen atom or a methyl group. The main component is an oligomer obtained by reacting an acrylic compound represented by the following formula:

Here, in the polyalkylene glycol represented by the general formula (1), when m is 2 or less, the water resistance of the coating material deteriorates, and when m is 7 or more, synthesis is difficult, and
The fluidity of the resulting oligomer is also impaired. When n is 5 or less, the flexibility is inferior, and when it exceeds 100, the functional group concentration becomes too low and the curing is slowed. Incidentally, these repeating units C _m H _2m O may be linear or branched. In this case, as the polyalkylene glycol, n is 10 to 7.
Polypropylene glycol, tetramethylene glycol, and copolymers thereof are preferred.

Examples of the diisocyanate component having two isocyanate groups in one molecule include aromatic, aliphatic and alicyclic organic diisocyanates, such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hydrogenated 4 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and the like. In this case, as the diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate,
One or a mixture of two or more selected from hydrogenated 4,4'-diphenylmethane diisocyanate is desirable.

The compound represented by the formula (2) can be synthesized by reacting glycidyl acrylate with acrylic acid. In this case, it can be obtained by esterifying two hydroxyl groups of glycerin with acrylic acid. However, in order to react with isocyanate and further cure it well by irradiation, one hydroxyl group and two The higher the purity of the compound of the formula (2) having an acrylic group is, the more preferable the reaction is, and the reaction of glycidyl acrylate with acrylic acid is preferable because it is easy to obtain a high purity.
Desirable purity is 70% or more in terms of GPC peak area ratio, and more desirable purity is 80% or more.

Next, a preferred embodiment of the oligomer synthesis will be described. First, an intermediate having an isocyanate group at a molecular chain terminal can be obtained by reacting diisocyanate with a polyalkylene glycol of the formula (1) at a molar ratio of NCO / OH of 1.2 or more. In this case, if the molar ratio is smaller than 1.2, the probability that the molecular chain terminal is terminated by a hydroxyl group increases, which is not preferable. The preferred molar ratio is 1.
5 to 2.0.

Next, by reacting the obtained intermediate with the acrylic compound (2), an oligomer having two acrylic groups at both ends of the molecular chain can be obtained. The urethanization reaction proceeds easily by heating, but if necessary, an amine catalyst, a tin catalyst or a lead metal catalyst may be used.

The oligomer has a viscosity of 1,000 to 300,000 mPa · s at 25 ° C.,
It is preferably from 000 to 200,000 mPa · s.

In the coating material for a radiation-curable optical fiber of the present invention, a reactive diluent comprising an ethylenically unsaturated compound can be used in addition to the above oligomer. In that case, the reactive diluent is 5 parts per 100 parts by weight of the oligomer.
Although it can be used in an amount of up to 200 parts by weight, it is particularly desirable to add 10 to 100 parts by weight. If the amount of the reactive diluent is less than 5 parts by weight, the effect of lowering the viscosity is small, and if it is more than 200 parts by weight, the properties of the cured film are impaired. As the preferred reactive diluent, the following monofunctional, bifunctional, and polyfunctional compounds can be used.

(Monofunctional compound) Examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylacetamide, N-vinylformamide, and the like. Examples of compounds having a structure in which (meth) acrylic acid is bonded by an amidation reaction or an esterification reaction include methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, and nonylphenoxypolyethylene glycol (meth). ) Acrylate, nonylphenoxy polypropylene glycol (meth) acrylate, 3-
Chloro-2-hydroxypropyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, butoxypolyethylene glycol (meth) acrylate,
Alkyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, cumylphenol (meth)
Acrylate, cumylphenoxy polyethylene glycol (meth) acrylate, cumylphenoxy polypropylene glycol (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dicyclopentadiene (meth)
Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, 3-acryloyloxyglycerin mono (meth) acrylate, 2
-Hydroxybutyl (meth) acrylate, 2-hydroxy-1- (meth) acryloxy-3- (meth) acryloxypropane, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polyε-caprolactone mono ( (Meth) acrylate, dialkylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, mono [2- (meth) acryloyloxyethyl] acid phosphate, trichloroethyl (meth) acrylate, 2,2,3,3-tetrafluoro Propyl (meth) acrylate, 2,2,3,4,4,4-hexafluorobutyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopente Roxyalkyl (meth) acrylate, tricyclodecanyl (meth) acrylate, tricyclodecanyloxyethyl (meth) acrylate, tricyclodecanyloxyethyl (meth) acrylate, isobornyloxyethyl (meth) acrylate, morpholine (Meth) acrylate and the like.

(Bifunctional compound) As the bifunctional compound, specifically, di (meth) acrylate of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, Ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, glycol di (meth) acrylate, neopentylglycerin di (meth) acrylate, bisphenol A
Di (meth) acrylate of ethylene oxide adduct of bisphenol A, di (meth) acrylate of propylene oxide adduct of bisphenol A, di (meth) acrylate of 2,2′-di (hydroxyethoxyphenyl) propane,
Tricyclodecane dimethylol di (meth) acrylate, dicyclopentadiene di (meth) acrylate, pentane di (meth) acrylate, di (meth) acrylic acid adduct of 2,2-bis (glycidyloxyphenyl) propane, and the like. Can be

(Polyfunctional compound) Examples of the polyfunctional compound include trimethylolpropane tri (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol hexa. (Meth) acrylate, tris (acryloxymethyl)
Examples include isocyanurate, tris (acryloxyethyl) isocyanurate, tris (acryloxypropyl) isocyanurate, triallyl trimellitic acid, triallyl isocyanurate and the like.

In order to improve the curability by radiation, a known photopolymerization initiator can be used. Specific photopolymerization initiators include, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, 2,2-dimethoxy-
Benzophenone derivatives such as 2-phenylacetophenone, phenylacetophenone diethyl ketal, alkoxyacetophenone, benzylmethyl ketal, benzophenone, 3,3-dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, and benzoylbenzoic Alkyl acid,
Bis (4-dialkylaminophenyl) ketone, benzyl derivatives such as benzyl and benzylmethyl ketal, benzoin derivatives such as benzoyl and benzoinbutylmethyl ketal, benzoin isopropyl ether, 2-
Thioxanthone derivatives such as hydroxy-2-methylpropiophenone, 2,4-diethylthioxanthone and 2,4-dichlorothioxanthone, fluorene, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 , 2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1,2,2
4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,
And phosphine oxide derivatives such as 4,4-trimethylpentylphosphine oxide.

The compounding amount of the photopolymerization initiator is preferably 0 to 20 parts by weight, particularly preferably 0 to 3 parts by weight, per 100 parts by weight of the oligomer.

The coating material of the present invention may further include, if necessary,
Additives such as antioxidants, stabilizers such as ultraviolet absorbers, organic solvents, plasticizers, surfactants, silane coupling agents, coloring pigments, organic or inorganic particles, etc. within a range that does not impair the purpose of the present invention. can do.

The coating material for a radiation-curable optical fiber of the present invention can be prepared by mixing, stirring, and mixing the above-mentioned required components, and the viscosity of the coating material can be adjusted according to the ordinary production of an optical fiber core in terms of workability. Normally, 500 to 20,000 from the compatibility with the conditions
00 cp (25 ° C.), especially under high-speed manufacturing conditions,
A range of 0 to 10,000 cp (25 ° C.) is desirable.

When the radiation-curable optical fiber coating material of the present invention is used as a primary coating material (primary material) for an optical fiber coating material, it is directly coated on the optical glass fiber to form a cured film. 0.1 to protect the core from microbends due to external forces and temperature changes
It is desirable to have a Young's modulus of not more than kgf / mm ² . Further, a secondary coating material (secondary material) is coated on the upper layer for the purpose of mechanically protecting the optical fiber. When used as this secondary coating material, 30 kgf / mm is used.
It is desirable to have a Young's modulus of ² or more. These Young's modulus adjustment is possible by changing the value of n alkylene glycol HO of the following general formula for use in the present invention _{(1) (C m H 2m} O) n -H (1). When used as a primary coating material, n = 50 to 100 is desirable, and a reactive diluent used in combination should have a glass transition temperature of 10 ° C. or less after curing. Desirable for. When used as a secondary coating material, n is preferably from 6 to 50, and the reactive diluent used in combination preferably has a glass transition temperature of 50 ° C. or higher after curing in order to prevent a decrease in Young's modulus at a high temperature. The gel fraction of the cured film of the primary coating material and the secondary coating material is 90
% Is desirable.

The radiation for curing the liquid radiation-curable resin composition of the present invention includes infrared rays, visible rays, ultraviolet rays, and ionizing radiations such as X-rays, electron beams, α-rays, β-rays, and γ-rays. Electron beams have high energy efficiency and are suitable for curing optical fiber coating materials. However, electron beams accelerated at a low acceleration voltage of 150 kV or less are used because they do not increase transmission loss.
It is preferable to irradiate with a dose of Mrad or less. 150
If it is larger than kV, the transmission loss of the optical fiber increases, and if it is larger than 3 Mrad, crosslinking of the coating material proceeds,
A problem that elongation is reduced may occur. In this case, it is preferable to apply the coating material to the optical fiber to a thickness of 20 to 65 μm. If it is less than 20 μm, it becomes difficult to prevent external stress, and if it is more than 65 μm, the fiber diameter becomes large, so that it becomes bulky and difficult to handle.

[0026]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The parts in each example are parts by weight.

Synthesis Example 1 200 parts (0.2 mol) of polypropylene glycol PP1000 (polyether manufactured by Sanyo Chemical Industries, Ltd.) having an average molecular weight of 1,000,
6-di-tert-butylhydroxytoluene 0.17
Parts and dibutyltin dilaurate (0.35 parts) were charged into a reaction vessel, and 69.6 parts (0.4 mol) of 2,4-tolylene diisocyanate were added dropwise at 20 ° C. over 1 hour under a stream of nitrogen. After further reacting at 35 ° C. for 1 hour, the formula CH ₂ ＣＨCHC
80 parts (0.4 mol) of a compound represented by OOCH ₂ CH (OH) CH ₂ OCOCH ＝ CH ₂ was added dropwise over 30 minutes and reacted at 65 ° C. for 4 hours, each having two acrylic groups at both ends. Oligomer A was obtained. This is 25
It was a pale yellow liquid having a viscosity of 149,000 mPa · s at ° C.

[Synthesis Example-2] 204 parts (0.05 mol) of polypropylene glycol PP4000 having an average molecular weight of 4,073 (polyether manufactured by Sanyo Chemical Industries, Ltd.)
2,6-di-tert-butylhydroxytoluene
12 parts and 0.24 parts of dibutyltin dilaurate were charged into a reaction vessel, and 17.4 parts (0.1 mol) of 2,4-tolylene diisocyanate was added dropwise at 20 ° C. over 30 minutes under nitrogen. After further reacting at 35 ° C. for 1 hour, the formula CH ₂ ＣC
20 parts (0.1 mol) of a compound represented by HCOOCH ₂ CH (OH) CH ₂ OCOCH ＝ CH ₂ are added dropwise over 30 minutes, reacted at 65 ° C. for 4 hours, and has two acrylic groups at both ends. Oligomer B was obtained. This is 2
It was a pale yellow liquid having a viscosity at 5 ° C of 26,000 mPa · s.

[Comparative Synthesis Example-1] Average molecular weight 1,000
200 parts (0.2 mol) of polypropylene glycol PP1000 (polyether manufactured by Sanyo Chemical Industries, Ltd.),
2,6-di-tert-butylhydroxytoluene
17 parts and dibutyltin dilaurate (0.35 parts) were charged into a reaction vessel, and 69.6 parts (0.4 mol) of 2,4-tolylene diisocyanate were added dropwise at 20 ° C. over 1 hour under a stream of nitrogen. After further reacting at 35 ° C. for 1 hour, 46.4 parts (0.4 mol) of hydroxyethyl acrylate was added dropwise over 30 minutes, reacted at 65 ° C. for 4 hours, and oligomer C having one acrylic group at each end was obtained. I got This was a pale yellow liquid having a viscosity of 204,000 mPa · s at 25 ° C.

[Comparative Synthesis Example-2] Average molecular weight 4,073
204 parts (0.05 mol) of polypropylene glycol PP4000 (polyether manufactured by Sanyo Chemical Industries, Ltd.), 0.12 parts of 2,6-di-tert-butylhydroxytoluene and 0.24 parts of dibutyltin dilaurate in a reaction vessel Charge and add 17.4 parts (0.1 mole) of 2,4-tolylene diisocyanate at 20 ° C. under a stream of nitrogen.
Dropped over minutes. After further reacting at 35 ° C. for 1 hour, 11.6 parts (0.1 mol) of hydroxyethyl acrylate was added to 3 parts.
The mixture was added dropwise over 0 minutes and reacted at 65 ° C. for 4 hours to obtain an oligomer D having one acryl group at each end.
This was a pale yellow liquid having a viscosity of 13,000 mPa · s at 25 ° C.

Examples 1 and 2, Comparative Examples 1 and 2 As shown in Table 1, the acrylate oligomer synthesized above and a reactive diluent containing an ethylenically unsaturated group were mixed. 2. The coating materials for radiation-curable optical fibers of Comparative Examples 1 and 2 were prepared. The properties of the composition thus obtained were measured as described below. Table 1 shows the results.

From the results shown in Table 1, the composition of the present invention has excellent radiation curability, and Example 1 has excellent physical properties for secondary coating of an optical fiber, and Example 2 has excellent physical properties for primary coating of an optical fiber. Things.

Evaluation method: (1) Preparation of cured film The radiation-curable resin composition was coated on a glass plate to a thickness of about 60 μm.
Electron beam with an acceleration voltage of 100 kV for 3 Mr.
Irradiation was performed to obtain a cured film. (2) Measurement of Gel Fraction After the cured film was immersed in acetone for 16 hours, the film was taken out, dried at 70 ° C. for 4 hours, and the weight change ratio was determined by the following formula. Gel fraction = (film weight after drying / initial film weight) × 100 (%) (3) Measurement of Young's modulus After conditioning the cured film at 25 ° C. and 50% relative humidity for 24 hours, the distance between the marked lines was 25 mm. , Pulling speed 1mm / m
A 2.5% tensile modulus (Young's modulus) was measured under the conditions of “in”. (4) Measurement of tensile strength and elongation at break After conditioning the cured film at 25 ° C. and 50% relative humidity for 24 hours, the distance between the marked lines was 25 mm, and the tensile speed was 50 mm /
It was measured under the condition of min.

[0034]

[Table 1] * M-113: Nonylphenol EO-modified (n = 4) acrylate (manufactured by Toagosei Co., Ltd.)

[0035]

The liquid radiation-curable resin composition of the present invention cures well by irradiation with low-energy radiation, and satisfies the characteristics as a coating material for an optical fiber.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 6/44 301 C03C 25/02 B 4J034 F-term (Reference) 2H050 BA18 BB07Q BB14Q BB17Q BB33Q 4D075 DA01 DB13 DC21 EA21 4G060 AA03 AC16 CB08 CB09 4J002 CH05X CK02W EE037 EE047 EH076 EH146 EH156 EP016 EU016 EU026 EU196 EU237 EV307 EW046 EW147 FD157 GH01 4J011 QA03 QA07 QA08 QA12 QA13 QA18 QA26 QA26 QA26 QA24 QA24 QA24 QA24 SA20 SA22 SA24 SA25 SA26 SA28 SA29 SA34 SA38 SA42 SA44 SA54 SA58 SA59 SA61 SA64 SA75 SA78 SA84 UA01 UA03 UA04 UA06 WA02 WA07 4J034 BA08 DA01 DB04 DB07 DG04 DG06 DG08 DG09 FA02 FA04 FB01 FC01 HC22 HC01 HC03 HC04 HC64 HC67 HC71 HC73 JA21 LA13 LA23 LA33 MA18 MA24 QB11 RA07

Claims (3)

[Claims] An oligomer obtained by reacting a polyalkylene glycol represented by the following general formula (1) with a diisocyanate having two isocyanate groups in one molecule and an acrylic compound represented by the following formula (2): A coating material for a radiation-curable optical fiber, comprising: _{HO (C m H 2m O)} n -H (1) ( wherein, m is 3 to 6, n is a number of _{6~100.) CH 2 = CRCOOCH 2} CH (OH) CH 2 OCOCR = CH 2 (2) (In the formula, R represents a hydrogen atom or a methyl group.) 2. The radiation-curable light according to claim 1, comprising 100 parts by weight of the oligomer, 5 to 200 parts by weight of a reactive diluent, and 0 to 20 parts by weight of a photopolymerization initiator. Fiber coating material. 3. An optical fiber coated with the coating material according to claim 1 or 2 so as to have a film thickness of 20 to 65 μm, and irradiated with an electron beam accelerated at an acceleration voltage of 150 kV or less at a dose of 3 Mrad or less. A method for curing a coating material for an optical fiber, the method comprising curing.