JP4982209B2 - Radiation curable resin composition - Google Patents

Description

  The present invention relates to a liquid curable resin composition for forming a cladding layer of a polymer-clad optical fiber.

  As information communication cables, optical fibers suitable for high-capacity, high-speed digital signal communication are being widely used instead of so-called electric wires made of metal wires that have been used conventionally. Various types of optical fibers are known depending on the structure and form of the optical fiber. The most basic structure of the optical fiber core is a core layer made of glass, quartz or transparent resin, and the core layer. The clad layer is provided in contact with the outer side, and the outer side of the clad layer is further provided with a polymer coating layer made of a radiation curable resin or the like. Among these, all-silica optical fibers in which the core layer and the cladding layer are both made of quartz are frequently used. The typical diameter of the optical fiber core is about 125 μm when the core layer is combined with about 50 μm and the cladding layer, and is about 250 to 500 μm when the resin coating layer is combined.

  On the other hand, optical modules with various functions such as optical signal transmission, reception, branching, and switching have been developed for various optical information communications, and the optical axes of these optical modules and optical fiber cores are aligned. It is known that the connection is important in suppressing attenuation of the optical signal. Since the diameter of the core layer of the conventional optical fiber core wire is small as described above and it is difficult to align the optical axis when connecting to the optical module, an optical fiber core wire having a core diameter increased to about 200 μm is used. .

  Since the optical fiber core having such a large diameter typically has a clad layer made of a curable transparent resin, it is also referred to as a polymer clad optical fiber (also called a plastic clad optical fiber or a polymer clad fiber). .)is called. As the curable transparent resin constituting the cladding layer, an example using a fluorine-containing ultraviolet curable composition containing a fluorine-containing urethane (meth) acrylate, a fluorine-containing (meth) acrylate oligomer or the like is known (patent) Literatures 1-3).

  Further, among polymer clad optical fibers, a type having a core layer made of glass or quartz is called a hard polymer clad optical fiber, and a type having a core layer made of a transparent resin is called a plastic fiber. A hard plastic clad optical fiber has a high optical transmission efficiency and is therefore used for communication over a relatively long distance. A plastic fiber is used for communication over a relatively short distance.

  The curable transparent resin material used for the clad layer of such a polymer clad optical fiber has a low refractive index and a stable transparency over time; an appropriate viscosity for obtaining good coatability. It is required to have properties such as excellent adhesion to the core layer, strength expressed by Young's modulus, breaking strength, elongation at break, and flexibility.

However, with resin materials used for the clad layer of conventional polymer clad optical fibers, a polymer clad layer with a low refractive index and transparency, good coatability, adhesion to the core layer, and excellent strength and flexibility can be obtained. In particular, there is a problem that it is difficult to obtain a polymer clad layer having stable transparency even when the polymer clad optical fiber is left in a high temperature environment.
Japanese Patent Laid-Open No. 10-10340 JP-A-10-160947 JP 11-1119036 A

  The object of the present invention is to provide characteristics suitable as a clad material for polymer clad optical fibers, and in particular, it has excellent low refractive index and stable transparency, good coatability, adhesion to the core layer, strength and flexibility. The object is to provide a radiation curable resin composition.

  Therefore, the present inventor has such a purpose with a radiation curable resin composition having a specific fluorine-containing polymer, a specific fluorine-containing (meth) acrylate monomer, and a (meth) acrylate monomer having a specific structure not containing fluorine as essential requirements. I have found that I can achieve it.

That is, in the present invention, the total amount of the composition is 100% by mass,
(A) 20 to 65% by mass of an ethylenically unsaturated group-containing fluorine-containing copolymer,
(B) 20-60 mass% of a compound represented by the following formula,
^{_{CH 2 = CR 8 COO (CH}} 2) x (CF 2) y X
[Wherein R ⁸ represents a hydrogen atom or a methyl group, X represents a hydrogen atom or a fluorine atom, x represents 1 to 2, and y represents 2 to 8]
And (C) a component other than the components (A) and (B), having no aromatic structure and polar group, and having 2 or more ethylenically unsaturated groups in an amount of 10 to 35% by mass.
The radiation curable resin composition to be contained is provided.

  The polymer clad layer obtained by the resin composition of the present invention is particularly excellent in low refractive index and stable transparency, good coatability, adhesion to the core layer, strength and flexibility.

(A) Ethylenically unsaturated group-containing fluoropolymer:
The ethylenically unsaturated group-containing fluorinated polymer (A) is not particularly limited as long as it is a polymer having an ethylenically unsaturated group and a fluorine atom, but a fluorinated olefin-based polymer having an ethylenically unsaturated group in the side chain. A copolymer is preferred. By the component (A), the composition of the present invention exhibits basic performance as a material for forming a clad of a polymer clad optical fiber such as a low refractive index, high mechanical strength, and adhesion to a core layer such as glass or quartz.

  The ethylenically unsaturated group-containing fluorine-containing polymer is obtained by reacting the compound containing an ethylenically unsaturated group and an isocyanate group described below with the hydroxyl group of the hydroxyl group-containing fluorine-containing polymer.

(1) A compound containing an ethylenically unsaturated group and an isocyanate group:
The compound containing an ethylenically unsaturated group and an isocyanate group is particularly limited as long as it is a compound containing at least one ethylenically unsaturated group and at least one isocyanate group in the molecule. is not.
Moreover, since the curable resin composition mentioned later can be hardened more easily as said ethylenically unsaturated group, the compound which has a (meth) acryloyl group is more preferable.
Such compounds include (meth) acrylic acid, (meth) acryloyl chloride, anhydrous (meth) acrylic acid, 2- (meth) acryloyloxyethyl isocyanate, 2- (meth) acryloyloxypropyl isocyanate, 1,1- (Bisacryloyloxymethyl) ethyl isocyanate may be used alone or in combination of two or more.
In addition, as a commercial item of the (meth) acrylate which has an isocyanate group, the Showa Denko Co., Ltd. make, brand name Karenz MOI, AOI, BEI etc. are mentioned, for example.

Such a compound can also be synthesized by reacting diisocyanate and a hydroxyl group-containing (meth) acrylate.
As examples of diisocyanates, 2,4-tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, methylene bis (4-cyclohexyl isocyanate), and 1,3-bis (isocyanate methyl) cyclohexane are preferred.

As examples of the hydroxyl group-containing (meth) acrylate, 2-hydroxyethyl (meth) acrylate and pentaerythritol tri (meth) acrylate are preferable.
Examples of commercially available hydroxyl group-containing polyfunctional (meth) acrylates include, for example, Osaka Organic Chemical Co., Ltd., trade name HEA; Nippon Kayaku Co., Ltd., trade name KAYARAD DPHA, PET-30; Aronix M-215, M-233, M-305, M-400, etc. can be obtained.

(2) Hydroxyl-containing fluoropolymer:
The hydroxyl group-containing fluoropolymer preferably comprises the following structural units (a), (b) and (c ′).
(A) A structural unit represented by the following formula (1).
(B) A structural unit represented by the following formula (2).
(C ′) A structural unit represented by the following formula (6).

  Structural unit (a):

[In the formula (1), R ¹ represents a hydrogen atom or a methyl group, m represents 1 to 8, and n represents 1 to 20]
Structural unit (b):

[In Formula (2), R ² represents a hydrogen atom or a methyl group, and R ³ represents a monovalent organic group having an alicyclic structure]
Structural unit (c ')

[In the formula (6), R ⁷ represents a hydrogen atom or a methyl group, and v represents a number of 1 to 20]

(I) Structural unit (a):
In said formula (1), m is 1-8, Preferably it is 1-4, More preferably, it is 2. n is 1 to 20, preferably 3 to 12, more preferably 4 to 8, and most preferably 8.
The structural unit (a) can be introduced by using a compound represented by the following formula (7) as a polymerization component. Typical examples of such compounds include perfluorooctylethyl (meth) acrylate.

Wherein (7), R ^1, m and n are each identical to R ^1, m and n in formula (1)]
The content of the structural unit (a) in the hydroxyl group-containing fluoropolymer is 20 to 70 mol%, where the total amount of the structural units (a), (b) and (c ′) is 100 mol%, preferably Is 30-60 mol%, More preferably, it is 35-60 mol%. When the content of the structural unit (a) exceeds 70 mol%, the solubility of the hydroxyl group-containing fluoropolymer is lowered and may be precipitated during the polymerization reaction, or the polymer may be unnecessary in the solvent. . On the other hand, if it is less than 20 mol%, the fluorine content of the hydroxyl group-containing fluoropolymer (weight ratio of fluorine atoms in the polymerization pair) decreases, and the refractive index of the hydroxyl group-containing fluoropolymer increases.

(Ii) Structural unit (b):
R ³ in the above formula (2) is a monovalent organic group having an alicyclic structure. When R ³ has an aliphatic structure, the Young's modulus of the cured product obtained by curing the composition of the present invention is too low, and when R ³ has an aromatic structure, the refractive index of the cured product is too high. In either case, the characteristics of the cladding layer are not suitable. When R ³ is a monovalent organic group having an alicyclic structure, the balance between the Young's modulus and the refractive index of the cured product is suitable. Here, the alicyclic structure includes a heterocyclic structure.

  The structural unit (b) can be introduced by using a compound represented by the following formula (8) as a polymerization component. Examples of such a compound include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and the like.

Wherein (8), R ² and R ³ are each the same as R ² and R ³ in the formula (2). ]
The content of the structural unit (b) in the hydroxyl group-containing fluoropolymer is preferably 10 to 70 mol%, with the total amount of the structural units (a), (b) and (c ′) being 100 mol%, preferably Is 20-60 mol%, More preferably, it is 20-55 mol%. When the content of the structural unit (b) exceeds 70 mol%, there is a side effect of increasing the refractive index of the fluoropolymer. On the other hand, if it is less than 20 mol%, there is a side effect of lowering the solubility of the fluoropolymer.

(Iii) Structural unit (c ′):
The structural unit (c ′) can be introduced by using a compound represented by the following formula (9) as a polymerization component. Such compounds include 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, caprolactone (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol ( A (meth) acrylate etc. can be used.

Wherein (9), R ⁷ and v are each identical to R ⁷ and v in equation (6). ]

  The content of the structural unit (c ′) in the hydroxyl group-containing fluoropolymer is 5 to 70 mol%, where the total amount of the structural units (a), (b) and (c ′) is 100 mol%, Preferably, it is 10-40 mol%, More preferably, it is 10-20 mol%. When the content of the structural unit (c ′) exceeds 70 mol%, there is a side effect of increasing the refractive index of the fluoropolymer. On the other hand, if it is less than 5 mol%, there is a side effect that the ethylenically unsaturated group may not be sufficiently introduced.

(3) Ethylenically unsaturated group-containing fluoropolymer:
The (A) component ethylenically unsaturated group-containing fluoropolymer is a compound containing a hydroxyl group, an ethylenically unsaturated group and an isocyanate group in the structural unit (c ′) of the hydroxyl group-containing fluoropolymer. It is obtained by reacting with a reactive group such as an isocyanate group. In this case, the number of moles of isocyanate groups contained in the compound containing an ethylenically unsaturated group and an isocyanate group is 0.5 to 1.0 times the number of moles of hydroxyl groups contained in the hydroxyl group-containing fluoropolymer. It is preferable.

Accordingly, (A) the ethylenically unsaturated group-containing fluoropolymer is a structural unit of a hydroxyl group-containing fluoropolymer in addition to the structural unit (a) and the structural unit (b) derived from the hydroxyl group-containing fluoropolymer. c ′) has the following structural unit (c) produced by reacting with a compound containing an ethylenically unsaturated group and an isocyanate group.
Structural unit (c);

[In Formula (3), R ⁴ represents a hydrogen atom or a methyl group, R ⁵ represents a group represented by the following Formula (4) or (5), and v represents 1 to 20.

(In formulas (4) and (5), R ⁶ represents a hydrogen atom or a methyl group)]

The content of the structural unit (a) in the ethylenically unsaturated group-containing fluorine-containing copolymer is the same as that of the hydroxyl group-containing fluorine-containing copolymer, and the structural units (a), (b) and (c ) Is 100-mol%, it is 20-70 mol%, preferably 30-60 mol%, more preferably 35-60 mol%.
The content of the structural unit (b) in the ethylenically unsaturated group-containing fluorine-containing copolymer is the same as that of the hydroxyl group-containing fluorine-containing copolymer, and the structural units (a), (b) and (c ) Is 100 to 70 mol%, preferably 20 to 60 mol%, more preferably 20 to 55 mol%.
The content of the structural unit (c) in the ethylenically unsaturated group-containing fluorine-containing copolymer is the same as that of the hydroxyl group-containing fluorine-containing copolymer, and the structural units (a), (b) and (c ) Is 25 to 70 mol%, preferably 5 to 40 mol%, and more preferably 5 to 20 mol%. When the content of the structural unit (c) exceeds 70 mol%, there is a side effect of increasing the refractive index of the fluoropolymer. On the other hand, if it is less than 5 mol%, the physical strength of the cured product tends to decrease.

The molecular weight of the ethylenically unsaturated group-containing fluorine-containing copolymer is preferably 5,000 to 500,000 as a polystyrene-equivalent number average molecular weight measured with tetrahydrofuran as a solvent by gel permeation chromatography (GPC). This is because when the number average molecular weight is less than 5,000, the mechanical strength of the cured product may be lowered. On the other hand, when the number average molecular weight exceeds 500,000, the composition has a high viscosity. This is because coating may be difficult.
For these reasons, the number average molecular weight in terms of polystyrene of the ethylenically unsaturated group-containing fluorine-containing copolymer is more preferably 10,000 to 300,000, and is preferably 10,000 to 100,000. Is more preferable.

  These (A) component-containing ethylenically unsaturated group-containing fluorine-containing copolymer is usually blended in an amount of 20 to 65% by mass, preferably 20 to 50% by mass, particularly preferably based on the total amount of the composition. 30-40 mass% is mix | blended. If the amount is less than 20% by mass, the viscosity of the composition becomes too small, so that the applicability at the time of manufacturing the optical fiber tends to decrease. If the amount exceeds 65% by mass, the blending amount of the component (B) and the component (C) is compressed. As a result, the solubility of the component (A) may be reduced, and it may be difficult to obtain a highly transparent cured product.

(B) component:
(B) A component is a compound represented by following formula (10).
^{_{CH 2 = CR 8 COO (CH}} 2) x (CF 2) y X (10)
[Wherein R ⁸ represents a hydrogen atom or a methyl group, X represents a hydrogen atom or a fluorine atom, x represents 1 to 2, and y represents 2 to 8]

  (B) A component is mix | blended in order to reduce the refractive index of hardened | cured material other than the objective of ensuring the solubility of (A) component with (C) component mentioned later. Specific examples of the component (B) are not particularly limited as long as they are compounds corresponding to the above formula (10), but 2-perfluorooctylethyl (meth) acrylate, 2,2,3,3, -tetrafluoropropyl (Meth) acrylate, 1H, 1H, 5H-octafluoropentyl (meth) acrylate and the like can be mentioned. Examples of these commercially available products include Biscote 17F, 4F, 8F, etc. (manufactured by Osaka Organic Chemical Industry Co., Ltd.). Among these, 2-perfluorooctylethyl (meth) acrylate is preferable because it is suitable for dissolving the component (A) and is easily available.

  Although (B) component is normally mix | blended 20-60 mass% with respect to the composition whole quantity, Preferably it is 20-50 mass%, Most preferably, it is 20-45 mass%. If the amount is less than 20% by mass, the solubility of the component (A) may be impaired, and the refractive index of the cured product may increase. If the amount exceeds 70% by mass, the viscosity of the composition decreases, and the coatability is reduced. Damaged.

  The compatibility between the (A) component ethylenically unsaturated group-containing fluorine-containing copolymer and the (meth) acrylate monomer is limited in many cases, but the (B) component and the later-described (C) component By mixing with the combination, the solubility is improved and a uniform composition can be obtained. In particular, the mixing ratio of the component (B) and the component (C) is preferably 2: 3 to 5: 1 as a mass ratio, and more preferably 2: 3 to 4: 1.

(C) Compound having no aromatic structure and no polar group and having two or more ethylenically unsaturated groups:
(C) component mix | blended with the composition of this invention is a compound which does not have an aromatic structure and a polar group other than (A) component and (B) component, and has two or more ethylenically unsaturated groups It is. Since the component (C) does not have a polar group, when used in combination with the component (B), the solubility of the component (A) is increased to give a uniform composition. Moreover, (C) component gives the hardened | cured material which has a low refractive index because it does not have an aromatic structure.
Here, the polar group includes polar groups such as a carbonyl group and an alkylene oxide group having 3 or less carbon atoms in addition to a dissociable group such as a carboxyl group and an amino group, but a hydroxyl group is excluded. The component (C) is not particularly limited as long as it has a structure that satisfies the above requirements.

  Specific examples of the component (C) include, for example, neopentyl glycol di (meth) acrylate, neopentyl glycol hydroxypivalate ester di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane trioxyethyl ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyester di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate Aliphatic structure containing (meth) acrylate etc. are mentioned.

  Among the components (C) listed above, monofunctional or polyfunctional aliphatic structure-containing (meth) acrylates are preferable, and neopentyl glycol di (meth) acrylate or neopentyl glycol hydroxypivalate ester di (meth) acrylate is preferable. Particularly preferred. (C) A component may be used individually by 1 type and may use 2 or more types together.

  Although (C) component is normally mix | blended 10-35 mass% with respect to the composition whole quantity, Preferably it is 15-35 mass%, Most preferably, it is 15-30 mass%. If the amount is less than 10% by mass, the solubility of the component (A) may be impaired. If the amount exceeds 35% by mass, the blending amount of the component (A) and the component (B) is compressed. The rate increases and the adhesion to the core layer is impaired.

  The composition of the present invention can further contain (D) (meth) acrylic acid or a dimer thereof. By blending the component (D), the adhesion between the core layer, particularly the core layer made of glass or quartz, and the clad layer can be improved.

  Although (D) component is normally mix | blended with 0-10 mass% with respect to the composition whole quantity, Preferably it is 1-7 mass%. If it exceeds 10% by mass, the storage stability of the composition may be impaired.

  When the composition of the present invention is cured by irradiation with light such as ultraviolet rays, it is desirable to incorporate (E) a photopolymerization initiator.

  Specific examples of (E) photopolymerization initiator include 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, 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 -Dimethoxybenzoyl) -2,4,4-trimethylpentylfophine oxide; IRGACURE 184, 369, 651, 500, 907, CGI 1700, CGI 1750, CGI 1850, CG 24-61; Darocur 1116, 1173 (above, Ciba Specialty Chemicals Lucirin TPO (manufactured by BASF); Ubekrill P36 (manufactured by UCB) and the like.

  (E) When using a photoinitiator, a photosensitizer can also be used together. Examples of the photosensitizer include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and 4-dimethylaminobenzoic acid. Isoamyl; Ubekryl P102, 103, 104, 105 (above, manufactured by UCB) and the like. Further, when the liquid curable resin composition of the present invention is cured by using heat and ultraviolet rays in combination, the thermal polymerization initiator and the photopolymerization initiator can be used in combination.

  (E) It is preferable to mix | blend a polymerization initiator 0.1-10 mass% with respect to the composition whole quantity, especially 0.3-7 mass%.

The composition of the present invention has no aromatic structure and polar group other than the components (F), (A), (B) and (C) as long as the effects of the invention are not impaired. A compound having one unsaturated group can be blended.
Specific examples of such a compound having no aromatic structure and a polar group and having one ethylenically unsaturated group include vinyl group-containing lactams such as N-vinylpyrrolidone and N-vinylcaprolactam;
Vinyl ethers such as hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether;
Acrylamides such as diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide t-octyl (meth) acrylamide;
Alicyclic structure-containing (meth) acrylates such as isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate;
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 (meta Acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol Aliphatic structure containing (meth) acrylates, such as (meth) acrylate, etc. are mentioned.

  Although (F) component is 0-30 mass% normally with respect to the composition whole quantity, Preferably it is 0-25 mass%, Most preferably, it is 0-20 mass%. If it exceeds 30% by mass, the transparency of the composition and its cured product may be impaired.

  The composition of the present invention has an ethylenically unsaturated group other than the components (G), (A), (B), (C), and (F) as long as the effects of the invention are not impaired. Can be blended. Examples of the component (G) include aromatic structure-containing (meth) acrylates and polar group-containing (meth) acrylates such as carboxyl groups and alkylene oxide structures. The component (G) tends to increase the refractive index of the cured product like the aromatic structure-containing (meth) acrylate, and also reduces the solubility of the component (A) like the polar group-containing (meth) acrylate. Since there exists a tendency, it is preferable that the compounding quantity of (G) component shall be 5 mass% or less by making the composition whole quantity into 100 mass%.

  As commercial products of these (G) components, for example, Iupimer UV, SA1002 (above, manufactured by Mitsubishi Chemical Corporation), Aronix M-215, M-315, M-325 (above, manufactured by Toagosei Co., Ltd.), Sartomer CN4000 (Sartomer) -Company Ink), Aronics TO-1210 (manufactured by Toagosei Co., Ltd.), and the like.

  In the composition of the present invention, various additives, for example, an antioxidant, a colorant, an ultraviolet absorber, a light stabilizer, a silane coupling agent, and a thermal polymerization, as long as they do not impair the characteristics of the present invention. Inhibitors, leveling agents, surfactants, storage stabilizers, plasticizers, lubricants, solvents, fillers, anti-aging agents, wettability improvers, coating surface improvers and the like can be blended.

  The viscosity of the composition of the present invention is preferably 0.8 to 5.0 Pa · s, particularly preferably 1.5 to 6 Pa · s at 25 ° C.

  In addition, although the liquid curable resin composition of this invention is hardened | cured with radiation, in addition to radiation curing, it can also use thermosetting together. Here, the radiation refers to infrared rays, visible rays, ultraviolet rays, X-rays, electron beams, α rays, β rays, γ rays, and the like.

  The cured product of the liquid curable composition of the present invention preferably exhibits a Young's modulus of 200 MPa to 500 MPa. Moreover, in order to form an upjacket layer, it is preferable to coat to a film thickness of 100 to 350 μm. Furthermore, a cable layer made of a thermoplastic resin can be provided in contact with the outside of the optical fiber upjacket layer.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples at all.

Production Example 1 (Synthesis 1 of hydroxyl group-containing fluoropolymer):
A 500 mL separable flask is charged with 66 g of 2-perfluorooctylethyl acrylate, 28 g of isobornyl acrylate, 6 g of hydroxyethyl acrylate, 150.0 g of 2-butanone (methyl ethyl ketone) as a solvent, and then azobisisobutyro Nitrile (1 g) was charged, and the temperature was raised in an oil bath. The reaction was continued at 80 ° C. with stirring under reflux. After 6 hours, the oil bath was removed to stop the reaction, and a polymer solution having a solid content concentration of about 40% was obtained. The obtained polymer solution was put into methanol to precipitate a polymer, washed with methanol, and vacuum dried at 50 ° C. to obtain 80 g of a hydroxyl group-containing fluoropolymer. Monomer conversion was greater than 95%. This is designated as “hydroxyl group-containing fluoropolymer 1”.

Production Example 2 (Synthesis 2 to 5 of hydroxyl group-containing fluoropolymer):
A hydroxyl group-containing fluoropolymer was obtained in the same manner as in Production Example 1 except that the following table was followed. In all cases, monomer conversion was greater than 95%. The contents of Table 1 are shown in Table 2 in terms of mol% when the total amount of the components (a), (b) and (c) is 100 mol%. In Tables 1 and 2, component (a) is 2-perfluorooctylethyl acrylate, component (b) is isobornyl acrylate, and component (c) is hydroxyethyl acrylate. It is.

Production Example 3 ((A) Synthesis of ethylenically unsaturated group-containing fluorine-containing copolymer):
In a 1-liter separable flask equipped with a magnetic stirrer, a glass cooling tube and a thermometer, 41.0 g of the hydroxyl group-containing fluoropolymer 1 obtained in Production Example 1 was used as a polymerization inhibitor, 2,6-di- -0.01 g of t-butylmethylphenol, 41.0 g of 2-perfluorooctylethyl (meth) acrylate as a diluting solvent, and 17.0 g of neopentylglycol di (meth) acrylate were charged, and hydroxyl-containing fluorine-containing heavy at 50 ° C. Stirring was performed until the coalescence 1 was dissolved and the solution became transparent and uniform.
Next, 2.0 g of 2-methacryloyloxyethyl isocyanate was added to this system and stirred until the solution became homogeneous, then 0.030 g of dibutyltin dilaurate was added to start the reaction, and the temperature of the system was changed to 55 to 55. By maintaining the temperature at 65 ° C. and continuing stirring for 5 hours, an ethylenically unsaturated group-containing fluoropolymer was obtained. The obtained ethylenically unsaturated group-containing fluoropolymer is referred to as “ethylenically unsaturated group-containing fluoropolymer 1”. The diluted solvent used at this time can be used as a component of the ultraviolet curable resin.

Production Example 4
In the same manner as above, “ethylenically unsaturated group-containing fluoropolymers 2 to 5” were obtained from the hydroxyl group-containing fluoropolymers 2 to 5, respectively.

Examples 1-7, Comparative Examples 1-5
Each component having the composition shown in Table 3 was charged into a reaction vessel equipped with a stirrer, and stirred for 1 hour while controlling the liquid temperature at 50 ° C. to obtain a liquid curable resin composition.

Test example 1
The liquid curable resin compositions obtained in the examples and comparative examples were cured by the following method to prepare test pieces, and the following evaluations were performed. The results are also shown in Table 3.

1. viscosity:
The viscosity at 25 ° C. of the compositions obtained in Examples and Comparative Examples was measured using a B-type viscometer.

2. Young's modulus:
A liquid curable resin composition was applied on a glass plate using an applicator bar having a thickness of 250 μm, and this was cured by irradiation with ultraviolet rays having an energy of 1 J / cm ² under nitrogen to obtain a film for measuring Young's modulus. . A strip-shaped sample was prepared from this film so that the stretched portion had a width of 6 mm and a length of 25 mm, and a tensile test was performed at a temperature of 23 ° C. and a humidity of 50%. The Young's modulus was determined from the tensile strength at 2.5% strain at a pulling speed of 1 mm / min.

3. Breaking strength and breaking elongation:
Using a tensile tester (manufactured by Shimadzu Corporation, AGS-50G), the breaking strength and breaking elongation of the test piece were measured under the following measurement conditions.
Tensile speed: 50 mm / distance between marked lines (measurement distance): 25 mm
Measurement temperature: 23 ° C
Relative humidity: 50% RH

4). Refractive index:
A resin composition was applied onto a glass plate using an applicator bar so that the film thickness was 200 μm, and 1.0 J / cm ² of ultraviolet light was irradiated under nitrogen to prepare a test piece. In accordance with JIS K7105, the refractive index at 25 ° C. was measured using an Abbe refractometer manufactured by Atago Co., Ltd.

5. Transparency (haze):
The total light transmittance of the cured film was measured according to JIS K7105 using a color haze meter (manufactured by Suga Test Instruments Co., Ltd.). The measurement was performed on the cured film immediately after production and on the cured film after being left at 120 ° C. for 72 hours. In Table 3, “whitening” means that each component in the composition was not completely dissolved, and the composition was visually cloudy.

6). Adhesion:
Regarding the compositions obtained in Examples and Comparative Examples, the adhesion strength stability of the cured products was measured. The liquid composition was applied on a slide glass using an applicator having a thickness of 381 μm, and irradiated with 0.1 J / cm ² of ultraviolet light in a nitrogen atmosphere to obtain a cured film having a thickness of about 200 μm. The cured film on the slide glass was allowed to stand for 24 hours at a temperature of 23 ° C. and a humidity of 50%. Thereafter, a strip-shaped sample was prepared from the cured film so that the stretched portion had a width of 10 mm. This sample was subjected to an adhesion test in accordance with JIS Z0237 using a tensile tester. The adhesion force was determined from the tensile strength at a tensile speed of 50 mm / min. In Table 3, “breakage” indicates that the cured film itself was broken without peeling off the interface between the cured film and the slide glass because of the strong adhesion.

7). Curing speed:
The composition was applied onto a quartz glass plate using an applicator having a thickness of 200 μm, and a 3.5 KW metal halide lamp (manufactured by Oak Co., SMX-3500 / F-OS) was used. Ultraviolet rays were irradiated under two conditions of ² and 1.0 J / cm ² to obtain a cured film. Next, after being allowed to stand at 23 ° C. and a relative humidity of 50% for 24 hours, a strip-shaped sample was prepared from the film so that the stretched portion had a width of 6 mm and a length of 25 mm, and was used as a test piece. Next, the Young's modulus (MPa) of the test piece was measured with a tensile tester. The value obtained by dividing the Young's modulus at an ultraviolet irradiation amount of 20 mJ / cm ^{2 by} the Young's modulus at 1 J / cm ² was taken as the curing rate.

In Table 3,
Biscoat 17F; 2-perfluorooctylethyl (meth) acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.).
Irgacure 184; 1-hydroxy-cyclohexyl-phenyl-ketone (Ciba Specialty Chemicals).
Lucirin: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF Japan).
Kyner ADS; copolymer of VDF / TFE / HFP vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene (manufactured by Arkema).

  As is apparent from Table 3, each example is excellent in the viscosity of the composition, the Young's modulus / mechanical strength (breaking strength and elongation at break), refractive index, and transparency (haze) of the cured product, and is exposed to high temperature conditions. It maintains good transparency even after. Moreover, the adhesive force with the quartz which is a material of a core layer is also favorable. On the other hand, in Comparative Example 1 in which the amount of the component (C) is excessive, the balance of the blending amount of the component (B) and the component (C) is broken, so that the solubility of the component (A) is reduced. The transparency of the cured product is inferior. In Comparative Example 2 using a hydroxyl group-containing fluoropolymer having no ethylenically unsaturated group instead of the component (A), the composition has an excessively low viscosity, and the fluoropolymer does not dissolve in the composition. Also inferior. Moreover, in the comparative example 3 using the fluoropolymer which does not correspond to (A) component, since a fluoropolymer does not melt | dissolve in a composition, transparency is inferior. In Comparative Example 4 that does not contain the component (B) and Comparative Example 5 that does not contain the component (C), the solubility of the hydroxyl group-containing fluoropolymer in the polymerization solvent was lowered, so a resin composition could not be obtained. .

Claims (6)

The total amount of the composition is 100% by mass,
(A) a structural unit (a) represented by the following formula (1), a structural unit (b) represented by the following formula (2), and a structural unit (c) represented by the following formula (3) ,
When the total amount of structural units (a), (b) and (c) is 100 mol%,
The content of the structural unit (a) is 35 to 60 mol%, the content of the structural unit (b) is 20 to 55 mol%, and the content of the structural unit (c) is 5 to 20 mol%. 20 to 65% by mass of an ethylenically unsaturated group-containing fluorine-containing copolymer,
Structural unit (a):

[In formula (1), R ¹ represents a hydrogen atom or a methyl group, m represents 1 to 8, and n represents 1 to 20]
Structural unit (b):

[In Formula (2), R ² represents a hydrogen atom or a methyl group, and R ³ represents a monovalent organic group having an alicyclic structure]
Structural unit (c):

[Wherein R ⁴ represents a hydrogen atom or a methyl group, R ⁵ represents a group represented by the following formula (4) or (5), and v represents 1 to 20]

(In formulas (4) and (5), R ⁶ represents a hydrogen atom or a methyl group)]
(B) 20-60 mass% of a compound represented by the following formula,
CH ₂ = CR ⁸ COO (CH ₂ ) _x (CF ₂ ) _y X
[Wherein R ⁸ represents a hydrogen atom or a methyl group, X represents a hydrogen atom or a fluorine atom, x represents 1 to 2, and y represents 2 to 8]
And (C) a component other than the components (A) and (B), having no aromatic structure and polar group, and having 2 or more ethylenically unsaturated groups in an amount of 10 to 35% by mass.
A radiation curable resin composition to be contained. Further, (D) (meth) acrylic acid or its dimer, based on the total amount of the composition, the radiation curable resin composition according to claim 1, further comprising 0 to 10 mass%. The radiation curable resin composition according to claim 1 or 2 , further comprising 0.1 to 10% by mass of (E) a photopolymerization initiator based on the total amount of the composition. Any one radiation-curable resin composition according to claim 1-3 is used for optical fiber cladding layer. The cured film which consists of hardened | cured material of the radiation curable resin composition of any one of Claims 1-4 . A polymer-clad optical fiber having a core layer made of glass, quartz, or a transparent resin, and a clad layer made of a cured film according to claim 5 in contact with the outside of the core layer.