JP4446466B2 - Manufacturing method of optical fiber multilayer coating and liquid curable resin composition for optical fiber coating - Google Patents

Description

  The present invention relates to a liquid curable resin composition from which a cured product having excellent surface characteristics can be obtained, and in particular, the surface of a cured product having surface characteristics suitable as a secondary material for optical fibers and various bundling materials is used at a predetermined concentration of oxygen. The present invention relates to a method for producing a multi-layer coating in which the adhesion with an adjacent layer is improved by irradiation with a low acceleration voltage electron beam in the presence, and a liquid curable resin composition capable of obtaining a high increase in adhesion.

  In the optical fiber industry, UV curable compositions are widely used in the manufacturing process of optical fibers, ribbons and cables. For example, a glass fiber is coated with an ultraviolet curable coating of at least one layer, most often two layers, immediately after being drawn from the base material so as to maintain the intrinsic properties of the glass fiber. It is common to call it a line. Of these two coating layers, the coating layer in close contact with the glass fiber is referred to as a primary coating layer, and the outer adjacent layer of the primary coating layer is referred to as a secondary coating layer. UV curable matrix materials and bundling materials also support and protect the individual cores of the coated fiber when the cores are bundled into optical fiber tape, optical fiber ribbon, optical fiber cable and related structures. can do. These coating layers are referred to as a matrix layer, a bundling layer, a tape layer, and the like, respectively. In addition, the ultraviolet curable ink can be used to identify each optical fiber core by attaching a color code, and this layer is called an ink layer. All of these various optical fiber coating materials are preferably UV curable. The first coating layer that is in direct contact with the glass fiber is called a primary coating layer, and is a flexible coating layer that prevents minute bending of the glass fiber. The second coating layer in contact with the outer side of the primary coating is called a secondary coating layer, which is a tougher coating layer that gives the glass fiber a more durable exterior.

  There are many reports on these optical fiber coating techniques (Patent Documents 1 to 3). It is exemplified as a typical primary coating material (Patent Literature 1), a secondary coating material (Patent Literature 5), and other coating materials (Patent Literatures 6 and 7).

Of these coating layers, the secondary material and the bundling material are required to have excellent mechanical properties such as a relatively high elastic modulus and high elongation at break. In addition, strands, tapes, cables, etc. after application of secondary material or bundling material are wound around bobbins, and storage, transportation, etc. are performed with the surfaces of the secondary material or bundling material in contact with each other. There is a need for materials with surface properties that do not join together. On the other hand, in order to identify a fiber or the like, it is desirable that the coating layer and the ink are not peeled off when coloring or printing with ink on the surface of the secondary material or the bundling material. Further, from the viewpoint of the strength of the optical fiber, each coating layer is required to have a certain adhesion. For this reason, conventionally, a method using a polydimethylsiloxane compound as an activity improver for the purpose of reducing the adhesion between the surfaces of the secondary material or the bundling material is known (Patent Documents 8 and 9). If the adhesiveness is reduced, there is a problem that coloring or printing with ink becomes difficult. In addition, a technique for reducing the adhesion between optical fibers by irradiating the optical fiber coating layer with an electron beam is also known (Patent Documents 10 and 11), but the adhesion between adjacent coating layers is increased. It has been difficult to achieve both the mechanical strength of the optical fiber.
US Pat. No. 5,336,563 US Pat. No. 5,595,820 US Pat. No. 5,1990,988 US Pat. No. 5,414,267 US Pat. No. 4,932,750 US Pat. No. 5,527,835 US Pat. No. 5,146,531 Japanese Patent Laid-Open No. 9-278850 Japanese Patent Laid-Open No. 9-328632 JP 2001-174680 A JP 2001-278461 A

An object of the present invention is to provide a method for manufacturing an optical fiber multilayer coating in which an optical fiber coating layer having sufficient surface properties is provided with sufficient adhesion to an adjacent coating layer.
Another object of the present invention is to provide a liquid curable resin composition for optical fiber coating in which a multilayer coating of a liquid curable resin cured product is produced by the above-described method, and the effect becomes more prominent.

  The present inventor has made various studies on means for imparting new surface characteristics to an optical fiber coating layer having sufficient surface characteristics. The optical fiber coating layer has a specific low acceleration voltage under a certain oxygen concentration condition. It was found that an optical fiber multilayer coating in which new surface characteristics were imparted to the surface of the coating layer could be obtained by irradiating the electron beam. Moreover, the liquid curable resin composition for optical fiber coating useful for the said multilayer coating layer formation was also discovered.

That is, the present invention provides a method for producing an optical fiber multilayer coating, wherein the surface of the optical fiber coating layer is irradiated with an electron beam having an acceleration voltage of 45 to 150 kV in the presence of 100 to 300 ppm of oxygen. is there.
The present invention also includes the following components (A), (B) and (C):
(A) Urethane (meth) acrylate 50-80% by weight,
(B) 20-50% by weight of reactive diluent,
(C) 1 to 5% by weight of a photopolymerization initiator,
A liquid curable resin composition for coating optical fibers, comprising 1 to 5% by weight of the total amount of urethane (meth) acrylate having a structure derived from a polyol prepolymer having a molecular weight of 8000 to 12000 in component (A) It provides things.
The present invention also includes the following components (A), (B) and (C):
(A) Urethane (meth) acrylate 50-80% by weight,
(B) 20-50% by weight of reactive diluent,
(C) 1 to 5% by weight of a photopolymerization initiator,
Provided is a liquid curable resin composition for coating an optical fiber, wherein 5 to 40% by weight of the component (B) is a reactive diluent having a methacryloyl group.

According to the method for producing an optical fiber multilayer coating of the present invention, it is possible to give an adhesive force to a coating layer adjacent to the coating layer such as a secondary coating layer or various bundling layers of an optical fiber, An optical fiber multilayer coating excellent in adhesion and mechanical strength can be obtained.
Moreover, the liquid curable resin composition for optical fiber coating of the present invention can impart effective adhesion to the optical fiber coating layer when used in the method for producing the optical fiber multilayer coating.

First, a method for manufacturing an optical fiber multilayer coating will be described.
The optical fiber coating layer to which the optical fiber multilayer coating manufacturing method of the present invention is applied is not particularly limited, and examples thereof include a secondary coating layer, an ink layer, a tape layer, a ribbon layer, and a bundling layer. By irradiating these coating layers with an electron beam according to the present invention, the adhesion with the coating layer adjacent to the outside of the coating layer is improved. For example, the adhesion between the secondary coating layer and the ink layer, the ink layer and the tape layer, etc. is improved.

  In the method for producing an optical fiber multilayer coating according to the present invention, the electron beam is usually irradiated with an acceleration voltage of 45 to 150 kV. The acceleration voltage is preferably 45 to 110 kV, more preferably 45 to 80 kV, and still more preferably 45 to 55 kV. When the acceleration voltage is 150 kV or less, the appearance and material properties of the glass fiber are not deteriorated by the electron beam. That is, when the acceleration voltage is 55 kV and the electron beam irradiation distance is 10 mm, the penetration depth of the irradiated electron beam is about 25 μm. Therefore, even if the surface of the secondary coating layer is irradiated with an electron beam, Does not reach the layer. In addition, the electron beam penetration depth can be controlled by maintaining the irradiation distance even when the acceleration voltage is 150 kV. Since the low accelerating voltage electron beam is used, the surface of the secondary coating layer can be modified while maintaining a flexible coating layer that prevents the minute bending of the glass fiber, which is a feature of the primary coating layer. On the other hand, if it is less than 45 kV, the irradiation dose decreases and sufficient adhesion cannot be obtained.

  The irradiation dose of the electron beam in the present invention is usually 1 to 24 Mrad, preferably 1 to 8 Mrad. If it exceeds 24 Mrad, problems such as low linear velocity occur, and if it is less than 1 Mrad, sufficient adhesion cannot be obtained.

  The oxygen concentration in the electron beam irradiation in the present invention is usually 100 to 300 ppm, preferably 200 to 300 ppm. If the oxygen concentration exceeds 300 ppm, there is an adverse effect on the generation of ozone, while if it is less than 100 ppm, sufficient adhesion cannot be obtained.

  The tube geometry used for electron beam irradiation can be widely varied to accommodate cylindrical optical fibers. As an example, the tubes may be arranged at an angle (eg, 120 °) to each other so that the coating on the optical fiber is irradiated with an electron beam to modify the surface, and then the ink is cured by ultraviolet light.

  The apparatus consists of a mechanism that passes an optical fiber coated directly beside the electron beam source in a continuous manner, such as an optical fiber drawing device. When the secondary material coating composition to be used is UV-cured and then irradiated with an electron beam, the opposing tubes can be effectively achieved in one pass if they are positioned on the left and right of the optical fiber. Although the distance between the beam and the material can be changed according to needs, a distance of about 0.5 to 2.0 cm from the window surface of the electron beam tube to the coating surface is effective.

  The optical fiber coating layer to which the method of the present invention is applied is preferably a cured product of a liquid curable resin composition containing (A) urethane (meth) acrylate. As for this (A) urethane (meth) acrylate, what contains 1 to 5 weight% of urethane (meth) acrylates which have the structure derived from the polyol prepolymer of molecular weight 8000-12000 of the composition whole quantity is more preferable. The liquid curable resin composition preferably further contains a reactive diluent and a polymerization initiator, and the reactive diluent is a reactive diluent having 5-40% by weight of methacryloyl group. More preferably. A particularly preferred embodiment of the liquid curable resin composition used here is a composition described later.

Next, the liquid curable resin composition for coating an optical fiber will be described.
While the method for producing an optical fiber multilayer coating of the present invention can be widely applied to various optical fiber coating materials, the method of the present invention is usually applied to a cured surface of a polymer coating that can be cured in an irradiation environment. , It is possible to improve the adhesion between the layer and the layer immediately above it. The resin composition at that time is not particularly limited, but is particularly high by using the liquid curable resin composition for coating optical fibers containing the components (A), (B) and (C). Improved adhesion can be obtained.

  The urethane (meth) acrylate that is the component (A) used in the liquid curable resin composition for coating an optical fiber of the present invention is not particularly limited. For example, (a) a polyol compound, (b) a polyisocyanate compound, and (C) Obtained by reacting a hydroxy-functional (meth) acrylate monomer. As a specific method for producing this (A) urethane (meth) acrylate, for example, (a) polyol, (b) polyisocyanate compound, and (c) hydroxy-functional (meth) acrylate monomer are charged all at once and reacted. (A) a polyol and (b) a polyisocyanate compound are reacted, and then (c) a hydroxy functional (meth) acrylate monomer is reacted; (b) a polyisocyanate compound and (c) a hydroxy functional compound. Examples include a method of reacting a (meth) acrylate monomer and then (a) a polyol, and this urethanization reaction occurs in the presence of a catalyst. Examples of the urethane reaction catalyst include dibutyltin diurarate.

  (A) The urethane (meth) acrylate preferably contains at least two (meth) acryloyl groups bonded to the oligomer main chain. For example, a (meth) acryloyl group may be present as a reactive end group at each end of the main chain of the oligomer. The main chain of the oligomer can be based on, for example, polyethers, polyolefins, polyesters, polycarbonates, hydrocarbons, or copolymers thereof. The main chain of the oligomer is preferably a polyol prepolymer such as polyether polyol, polyolefin polyol, polycarbonate polyol, or a mixture thereof. This polyol prepolymer usually contains a plurality of polyol prepolymers having a molecular weight of 200 to 12000. In the present invention, the composition having a high effect of improving the adhesion between the layer by electron beam irradiation and the immediately upper layer is used. It is preferable that the composition contains (A) urethane (meth) acrylate having a structure derived from a polyol prepolymer having a molecular weight of 8000 to 12000 in an amount of 1 to 5% by weight of the total amount of the composition.

  (A) Polyether diol, polyester diol, polycarbonate diol, etc. can be used as (a) polyol used for the synthesis | combination of urethane (meth) acrylate. Of these, polyether diols are preferred, but other diols can be used in combination with the polyether diol. The polymerization mode of these structural units is not particularly limited, and may be any of random polymerization, block polymerization, and graft polymerization.

  As the polyether diol, a polymer obtained by ring-opening polymerization of a kind of ion-polymerizable cyclic compound such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol. Examples thereof include polyether diols obtained by ring-opening copolymerization of ether olefin diols or two or more ion-polymerizable cyclic compounds. Examples of the ion polymerizable cyclic compound include ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, oxetane, 3,3-dimethyloxetane, 3,3-bischloromethyloxetane, tetrahydrofuran, 2-methyltetrahydrofuran, and 3-methyl. Tetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monooxide, isoprene monooxide, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, butyl Cyclic ethers such as glycidyl ether and benzoic acid glycidyl ester Ethers, and the like.

  In the case of using a polyether diol obtained by ring-opening copolymerization of a polyether olefin diol or two or more kinds of ion-polymerizable cyclic compounds, it preferably has an average of two or more hydroxyl groups. The oligomer main chain polyol may have an average of more than two hydroxyl groups. Examples of such oligomeric diols include polyether diols, polyolefin diols, polyester diols, polycarbonate diols, and mixtures thereof. Polyether diols, polyolefin diols, or combinations thereof are preferred. When polyether diol is used, it is preferably a substantially non-crystalline polyether. The polyether preferably contains one or more repeating units selected from the group of monomer units described below.

—O—CH ₂ —CH ₂ —
—O—CH ₂ —CH (CH ₃ ) —
—O—CH ₂ —CH ₂ —CH ₂ —
_{-O-CH (CH 3) -CH} 2 -CH 2 -
_{-O-CH 2 -CH (CH 3} ) -CH 2 -
—O—CH ₂ —CH ₂ —CH ₂ —CH ₂ —
_{-O-CH 2 -CH (CH 3} ) -CH 2 -CH 2 -
—O—CH (CH ₃ ) —CH ₂ —CH ₂ —CH ₂ —

  These polyether diols are, for example, PTMG650, PTMG1000, PTMG2000 (manufactured by Mitsubishi Chemical Corporation), Exenol 1020, 2020, 3020, Preminol NPML-4002, NPML-5005, Preminol S-4011 (above Asahi Glass Co., Ltd.) Manufactured), Unisafe DC1100, DC1800, DCB1000 (above, manufactured by NOF Corporation), PPTG1000, PPTG2000, PPTG4000, PTG400, PTG650, PTG1000, PTG2000, PTG-L1000, PTG-L2000 (above, Hodogaya Chemical Co., Ltd.) Manufactured), Z-3001-4, Z-3001-5, PBG2000 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Acclaim 2200, 2220, 3201, 3205, 42 0,4220,8200,12000 available as (or Lion Dale Corporation) commercially available products or the like. In the present invention, the composition containing 1 to 5% by weight of (A) urethane (meth) acrylate using preminol S-4011 is particularly effective in improving the adhesion between the layer and the immediately upper layer.

  (A) As polyisocyanate (b) used for the synthesis | combination of urethane (meth) acrylate, aromatic diisocyanate, alicyclic diisocyanate, aliphatic diisocyanate, etc. are mentioned. The specific compound is not particularly limited as long as it can be used as a resin composition for optical fibers. Preferred examples include aromatic diisocyanates and alicyclic diisocyanates, more preferably 2,4-tolylene diisocyanate and Examples include isophorone diisocyanate. These diisocyanate compounds may be used alone or in combination of two or more.

  (A) As the polyisocyanate (b) used for the synthesis of urethane (meth) acrylate, diisocyanate is preferable. Examples of polyisocyanate (b) include isophorone diisocyanate, tetramethylxylene diisocyanate, toluene diisocyanate, diphenylmethylene diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, methylenedicyclohexane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, m-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,5-naphthylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1, In addition to 10-decamethylene diisocyanate and 1,4-cyclohexylene diisocyanate, Compounds which at both ends diisocyanates such as toluene diisocyanate bound side or polyester glycol. These diisocyanates are preferably diisocyanates such as isophorone diisocyanate and toluene diisocyanate.

  (A) As a (c) hydroxy-functional (meth) acrylate monomer used for the synthesis of urethane (meth) acrylate, a hydroxyl group is bonded to a primary carbon atom in terms of reactivity with the isocyanate group of polyisocyanate. Hydroxy-functional (meth) acrylate monomers (referred to as primary hydroxyl group-containing (meth) acrylates) and hydroxyl-containing (meth) acrylates (referred to as secondary hydroxyl group-containing (meth) acrylates) in which the hydroxyl group is bonded to a secondary carbon atom. preferable.

  Examples of the primary hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, Examples include dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, and trimethylolethane di (meth) acrylate.

  As the secondary hydroxyl group-containing (meth) acrylate, for example, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclohexyl (meta) ) Acrylates, and the like, and compounds obtained by addition reaction of glycidyl group-containing compounds such as alkyl glycidyl ether, allyl glycidyl ether, glycidyl (meth) acrylate and (meth) acrylic acid. These hydroxy-functional (meth) acrylate monomers can be used alone or in combination of two or more.

  (A) Urethane (meth) acrylate is a liquid curable resin composition for coating an optical fiber of the present invention, from the viewpoint of obtaining good mechanical properties such as Young's modulus and elongation at break of the cured product and an appropriate viscosity of the resin composition. It is preferable to contain 50 to 80% by weight, particularly 60 to 80% by weight, based on the total amount of the composition. If it exceeds 80% by weight, the Young's modulus of the cured product is increased, so that it is not preferred as a resin for optical fiber coating, and the workability is also lowered because the viscosity of the curable resin composition exceeds 10.0 Pa · s. If it is less than 50% by weight, the breaking strength is deteriorated.

  Component (A) contains 1 to 5% by weight of (A) urethane (meth) acrylate having a structure derived from a polyol prepolymer having a molecular weight of 8000 to 12000, based on the total amount of the composition. A preferable content is 1 to 3% by weight. By containing 1 to 5% by weight of such (A) urethane (meth) acrylate, it has suitable surface characteristics, and sufficient adhesion to the adjacent coating layer can be imparted by irradiation with a low acceleration voltage electron beam.

  The component (B) reactive diluent used in the liquid curable resin composition for coating an optical fiber of the present invention is a monomer having an ethylenically unsaturated group copolymerizable with the component (A). This reactive diluent can be used to adjust the viscosity of the coating composition. Accordingly, the reactive diluent is a low viscosity monomer having at least one functional group capable of being polymerized when exposed to actinic radiation.

  Examples of the component (B) include (B1) a polymerizable monofunctional compound and (B2) a polymerizable polyfunctional compound. (B1) Polymerizable monofunctional compounds include vinyl group-containing lactams such as N-vinylpyrrolidone and N-vinylcaprolactam, isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, di Cyclopentanyl (meth) acrylate, (meth) acrylate having an alicyclic structure such as 4-butylcyclohexyl (meth) acrylate, (meth) acrylate having an aromatic ring structure such as benzyl (meth) acrylate, acryloylmorpholine, vinyl Imidazole, vinyl pyridine, 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 (meth) 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, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofur Ryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (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, diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, t- Octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acryl Rate, 7-amino-3,7-dimethyloctyl (meth) acrylate, N, N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2 -Ethylhexyl vinyl ether can be mentioned.

  Examples of the polymerizable polyfunctional compound (B2) include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and polyethylene glycol. Di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, Tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate Di (meth) acrylate of bisphenol A ethylene oxide or propylene oxide adduct diol, di (meth) acrylate of hydrogenated bisphenol A ethylene oxide or propylene oxide adduct diol, (meth) acrylate to diglycidyl ether of bisphenol A And epoxy (meth) acrylate to which is added, triethylene glycol divinyl ether, and the like.

  Moreover, as a commercial item, for example, light acrylate 9EG-A and light acrylate 4EG-A (manufactured by Kyoeisha Chemical Co., Ltd.), Iupimer UV SA1002, SA2007 (above, manufactured by Mitsubishi Chemical Corporation); KAYARAD R-604, DPCA-20, -30, -60, -120, HX-620, D-310, D-330 (above, Nippon Kayaku Co., Ltd.); Aronix M-210, M-215, M-315, M-325 (above, Toagosei Co., Ltd. product) etc. are mentioned.

  These components (B) are preferably contained in the liquid curable resin composition for coating an optical fiber of the present invention in an amount of 1 to 60% by weight, preferably 2 to 45% by weight, based on the total amount of the composition. Is more preferable. If it is less than 1% by weight, the curability may be impaired. If it exceeds 60% by weight, the coating shape changes due to low viscosity, and the coating is not stable. Furthermore, when 5 to 40% by weight of the total amount of component (B) has a methacryloyl group, the coating layer is sufficiently adjacent to the cured product surface of the liquid curable resin composition having sufficient surface properties by irradiation with a low acceleration voltage electron beam. It is possible to provide an adhesion force with.

  The liquid curable resin composition for coating an optical fiber of the present invention can be cured by various radiations. Here, the radiation refers to infrared rays, visible rays, ultraviolet rays, X-rays, electron beams, α rays, β rays, γ rays, and the like. When the resin composition of the present invention is cured by radiation, (C) a polymerization initiator can be added. As the component (C), a photopolymerization initiator is used. (C) Examples of the photopolymerization initiator include benzophenone and acetophenone derivatives such as α-hydroxyalkylphenyl ketone, benzoin alkyl ether and benzyl ketal; or acylphosphine oxide; other bisacylphosphine oxides; or titanocene.

  (C) Specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3- Methyl acetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy 2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthate 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis- (2,6- And dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide. The commercially available products include Irgacure 184, 369, 651, 500, 907, 819, CGI 1700, CGI 1750, CGI 1850, CGI 1870, CG 2461, Darocur 1116, 1173 (above, manufactured by Ciba Specialty Chemicals); LUCIRIN TPO-X ( BASF); Ubekrill P36 (UCB) and the like.

  (C) The polymerization initiator is preferably blended in the radiation curable resin composition of the present invention in an amount of 0.1 to 10% by weight, particularly 0.5 to 5% by weight.

  When used for coating an optical fiber ribbon, a release agent may be included to facilitate peeling of the coating layer. As the release agent, silicone, fluorocarbon oil, resin or the like is suitable. When these release agents are used, it is preferable to contain 0.5 to 20% by weight of an appropriate release agent.

  In addition to the above components, the radiation curable resin composition of the present invention includes various additives such as colorants, silane coupling agents, leveling agents, surfactants, storage stabilizers, plasticizers, lubricants, solvents, fillers, An anti-aging agent, a wettability improver, a coating surface improver and the like can be blended as necessary.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, a part means a weight part.

[Synthesis example 1 of urethane acrylate]
A reaction vessel equipped with a stirrer was charged with 134.8 g of 2,4-toluene diisocyanate, 774.2 g of polypropylene oxide having a molecular weight of 2000, 0.24 g of 2,6-di-t-butyl-p-cresol, and 0.08 g of phenothiazine. It is. Next, 0.8 g of dibutyltin diurarate was added, and the mixture was stirred for 1 hour while controlling the liquid temperature at 25 to 35 ° C. Thereafter, 89.9 g of hydroxyethyl acrylate was added, stirring was continued for 1 hour at a liquid temperature of 50 to 60 ° C., and the reaction was terminated when the residual isocyanate was 0.1% by weight or less to obtain urethane acrylate. This urethane acrylate is referred to as “UA-1”.

[Synthesis example 2 of urethane acrylate]
A reaction vessel equipped with a stirrer was charged with 428.1 g of 2,4-toluene diisocyanate, 0.24 g of 2,6-di-t-butyl-p-cresol, 0.08 g of phenothiazine, and 0.8 g of dibutyltin diurarate. Thereafter, 570.8 g of hydroxyethyl acrylate was added, stirring was continued for 1 hour at a liquid temperature of 50 to 60 ° C., and the reaction was terminated when the residual isocyanate was 0.1 wt% or less to obtain urethane acrylate. This urethane acrylate is referred to as “UA-2”.

[Synthesis example 3 of urethane acrylate]
A reaction vessel equipped with a stirrer was charged with 22.4 g of 2,4-toluene diisocyanate, 942.9 g of polypropylene oxide having a molecular weight of 10,000, 0.24 g of 2,6-di-t-butyl-p-cresol, and 0.02 g of phenothiazine. It is. Next, 0.8 g of dibutyltin diurarate was added, and the mixture was stirred for 1 hour while controlling the liquid temperature at 25 to 35 ° C. Thereafter, 33.6 g of hydroxyethyl acrylate was added, stirring was continued for 1 hour at a liquid temperature of 50 to 60 ° C., and the reaction was terminated when the residual isocyanate became 0.1% by weight or less to obtain urethane acrylate. This urethane acrylate is referred to as “UA-3”.

[Example 1, Reference Examples 1 to 3 and Comparative Examples 1 and 2]
The compounds were charged in a reaction vessel equipped with a stirrer at the blending ratio shown in Table 1, and stirred at a liquid temperature of 50 ° C. until a uniform solution was obtained, thereby obtaining each composition.

〔experimental method〕
(1) Film forming conditions: A resin composition was applied on a quartz glass plate using an applicator having a thickness of 130 μm, and a UV irradiation amount of 0.5 J / cm ² was applied in a nitrogen atmosphere using a 3.5 KW metal halide lamp. The film was irradiated with ultraviolet rays to obtain a cured film. The film was then irradiated with an electron beam with an irradiation dose of 4 Mrad. Then, the resin composition of the adjacent layer was applied onto the cured resin film using a bar coater having a finished film thickness of 7 μm, and then ultraviolet rays were used under a condition of an ultraviolet ray irradiation amount of 20 mJ / cm ^{2 in} an air atmosphere using a 3.5 KW metal halide lamp. Was irradiated to obtain a measurement sample.

(2) Electron beam irradiation conditions: Glass in which the resin composition is cured is placed in a conveyor of an electron beam irradiation apparatus. Thereafter, the cured film is irradiated with an electron beam having a total irradiation dose of 4 Mrad by irradiating the electron beam with 1 pass at an acceleration voltage of 110 kV, a tube current of 3.8 mA, a conveyor speed of 10 m / min, and an irradiation distance of 10 mm. The atmosphere at that time was a nitrogen atmosphere, and the oxygen concentration was 200 to 300 ppm.

(3) Adhesion strength measurement method: As a sample before electron beam irradiation, the sample obtained by the above method (1) was allowed to stand for 24 hours, and then cut into a 1 cm wide strip. Ron Japan Co., Ltd.) and measured by a 180 degree peel method. Moreover, after leaving the sample obtained by the method of said (2) as a sample after electron beam irradiation for 24 hours, the adhesive force was measured like the sample before electron beam irradiation.

  The composition obtained in the Examples was irradiated with an electron beam under the condition (2) after ultraviolet curing, the resin composition of the adjacent layer was ultraviolet cured on the upper layer, and the adhesion was evaluated. The results are shown in Table 1.

As is apparent from Table 1, the cured product of the urethane (meth) acrylate-containing liquid curable resin composition is irradiated with an electron beam having an acceleration voltage of 45 to 150 kV under an oxygen condition of 100 to 300 ppm. A layer having good adhesion can be formed on the surface. Moreover, the composition of Example 1 which mix | blended UA-3 containing 1 to 5 weight% of urethane (meth) acrylates which have a structure derived from a polyol prepolymer having a molecular weight of 800 to 12000 in the component (A), and the component ( It can be seen that the composition of Reference Example 3 in which 5 to 40% by weight of B) is blended with a reactive diluent having a methacryloyl group has a particularly excellent adhesion improving effect.

Claims (2)

On the surface of the optical fiber coating layer, the following components (A), (B) and (C):
(A) Urethane (meth) acrylate 50-80% by weight,
(B) 20-50% by weight of reactive diluent,
(C) 1 to 5% by weight of a photopolymerization initiator,
After applying a liquid curable resin composition for coating optical fibers containing 1 to 5% by weight of the total amount of urethane (meth) acrylate having a structure derived from a polyether polyol having a molecular weight of 8000 to 12000 in component (A) The composition is cured by irradiating ultraviolet rays to form a secondary coating layer or bundling layer, and then irradiated with an electron beam having an acceleration voltage of 45 to 150 kV in the presence of 100 to 300 ppm of oxygen, Manufacturing method of optical fiber multilayer coating. The following components (A), (B) and (C):
(A) Urethane (meth) acrylate 50-80% by weight,
(B) 20-50% by weight of reactive diluent,
(C) 1 to 5% by weight of a photopolymerization initiator,
A secondary coating layer of an optical fiber comprising 1 to 5% by weight of urethane (meth) acrylate having a structure derived from a polyether polyol having a molecular weight of 8000 to 12000 in component (A), or A liquid curable resin composition for forming a bundling layer.