JPH03247671A - Ultraviolet ray curable resin composition for optical fiber coating - Google Patents

Abstract

PURPOSE:To obtain the title composition containing a specific polymerizable unsaturated compound and photopolymerization initiator, being small in variation of transmission loss of light signals caused by temperature change of circumstance and useful for quartz based optical fiber. CONSTITUTION:The aimed composition containing (A) a polymerizable unsaturated compound (e.g. trimethylolpropane triacrylate) being >=100 deg.C in glass transition temperature of homopolymer and having >=2 acryloyl groups, (B) photopolymerization initiator (e.g. benzoin ethyl ether or benzophenone) and preferably (C) a polymerizable unsaturated polyurethane obtained by reacting a hydroxy compound having a polyoxyalkylene block with a hydroxy compound having acryloyl group and polyisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultraviolet curable resin composition for coating optical fibers. In particular, the present invention relates to a material for a secondary coating layer and a material for a tape coating layer used in a silica-based optical fiber.

[Conventional technology]

In the production of optical fibers, an ultraviolet curable resin coating is applied immediately after thermal melt spinning of the optical fiber for the purpose of protection and reinforcement. As this resin coating, a structure in which a primary coating layer with a small elastic modulus is first provided on the surface of the optical fiber, and a secondary coating layer with a large elastic modulus is further provided on the outside thereof is well known. Furthermore, a structure in which two to ten optical fibers coated with a secondary coating layer are bundled together and a tape coating layer is provided for fixing with resin is also well known. The secondary coating layer and the tape coating layer usually have an elastic modulus of 20 to 100 kg f.
/1m'' ultraviolet curing resin is used.

[Problem to be solved by the invention]

By the way, the materials of the secondary coating layer and the tape coating layer of the optical fiber have a temperature change in the elastic modulus in the practical temperature range, that is, in the temperature range of -30°C to 60°C, from the viewpoint of the transmission loss characteristics of the optical fiber. Although small materials are desired, conventional materials for the secondary coating layer and tape coating layer, which have an elastic modulus of 20 to 100 kgf/m'' at room temperature, are
The problem is that the temperature dependence of the elastic modulus is generally extremely large in the temperature range from 60°C to 60°C.

The problem to be solved by the present invention is to use optical fibers used as materials for the secondary coating layer and tape coating layer, which have an elastic modulus of 20 to 100 kgf/w'' at room temperature and have a small temperature dependence of the elastic modulus. An object of the present invention is to provide an ultraviolet curable resin composition for coating fibers.

[Means to solve the problem]

In order to solve the above problems, the present invention contains (1) a polymerizable unsaturated compound having two or more acryloyl groups whose homopolymer has a glass transition temperature of 100°C or higher, and (2) a photopolymerization initiator. An ultraviolet curable resin composition for coating an optical fiber is provided.

Various components constituting the ultraviolet curable resin composition for coating optical fibers of the present invention will be explained in detail below.

Examples of polymerizable unsaturated compounds that have two or more acryloyl groups and whose homopolymer has a glass transition temperature Tg of 100°C or higher include trimethylolpropane triacrylate (Tg=250°C or higher), trimethylol Propanetrioxyprobyl acrylate (Tg
= 120°C), pentaerythritol triacrylate (Tg = 250°C or higher), pentaerythritol tetraacrylate (Tg = 250°C or higher), trisyl 2-hydroxyethyl isocyanurate diacrylate (Tg = 250°C or higher),
= 161°C), tris-2-hydroxyethyl isocyanurate triacrylate (Tg = 250°C or higher), caprolactone-modified tris-2-hydroxyethyl isocyanurate triacrylate (Tg = 160°C), tricyclodecane dimetatool diacrylate (Tg=17
5℃), hydrogenated dicyclopentadiene diacrylate) (
Tg=175°C). These may be used alone or in combination of two or more. It is preferable to use the below-mentioned polymerizable unsaturated polyurethane in the ultraviolet curable resin composition for coating optical fibers of the present invention.

The polymerizable unsaturated polyurethane can be obtained by reacting (a) a hydroxy compound having a polyoxyalkylene block, (b) a hydroxy compound having an acryloyl group, and (c) a polyisocyanate.

Examples of the hydroxy compound having a polyoxyalkylene block include polyethylene glycol, polypropylene glycol, polytetramethylene glycol,
Examples include a copolymer of propylene oxide and ethylene oxide, a copolymer of tetrahydrofuran and propylene oxide, a copolymer of tetrahydrofuran and ethylene oxide, an ethylene oxide adduct of bisphenol, and a propylene oxide adduct of bisphenol A. Specifically, DEC600, 1000, 2000 (manufactured by Sanyo Chemical Co., Ltd.) as polyethylene glycol; DPG diol as polypropylene glycol;
1000.2000.3000 (Mikata Car Pressure Chemical);
Efsenol 1020.2020.3020 (manufactured by Asahi Glass); PTG 6 as polytetramethylene glycol
50°850, 1000.2000.4000 (manufactured by Hodogaya Chemical Co., Ltd.); As a copolymer of propylene oxide and ethylene oxide, HD-28 (manufactured by Mikata Kurahatsu), Efcenol 510 (manufactured by Asahi Glass Co., Ltd.): a copolymer of tetrahydrofuran and propylene oxide. DPTG 1000 as polymer.
2000°4000 (manufactured by Hodogaya Chemical), Unisafe D
CB-1100゜1800 (NOF type); Unisafe DC1100, 1800 (NOF type) as a copolymer of tetrahydrofuran and ethylene oxide; Uniol DA400, 700 (NOF type) as an ethylene oxide adduct of bisphenol A; Bisphenol A Uniol D as a propylene oxide adduct of
Examples include B-400 (NOF type).

Examples of hydroxy compounds having an acryloyl group include hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-h)'roxybutyl acrylate, phenoxyhydroxypropyl acrylate, butoxyhydroxypropyl acrylate, pentaerythritol acrylate, and dipentaerythritol monohydroxypentaacrylate. , trimethylolpropane diacrylate, dipropylene glycol monoacrylate, 1-6-hexanesiol monoacrylate, glycerin diacrylate, caprolactone-modified 2-hydroxyethyl acrylate, stearic acid-modified pentaerythritol diacrylate, and the like.

Examples of the polyisocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,
Xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate
Trimethylhexamethylene diisocyanate, 1.5
-naphthalene diisocyanate, tolidine diisocyanate), P-phenylene diisocyanate, lysine diisocyanate, and the like.

The polymerizable unsaturated polyurethane obtained in this manner preferably has a glass transition temperature of 140° C. or lower in its single cured film. The glass transition temperature depends on the molecular weight of the chemical structure of the hydroxy compound having a polyoxyalkylene block, the selection of the polyisocyanate compound, etc.
You can select the preferred one.

The photopolymerization initiator of the present invention may be one that generates radicals when exposed to light, and the radicals react efficiently with the polymerizable unsaturated compound. There are types in which the molecule cleaves to generate radicals, and types in which the molecules are used in combination, such as a combination of an aromatic ketone and a hydrogen donor. Examples belonging to the former include benzoylethyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-
Methyl-1-phenyl-propan-1-off, 2,4
．． 6-1-limethylbenzoyldiphenylphosphine oxide, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1one, 2-methyl-1
Examples of the latter include benzophenone, 4-phenylbenzophenone, isophthalophenone, and 4-benzoyl-4 as aromatic ketones. '-Methyl-diphenyl sulfide.

2.4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, etc.
As a hydrogen donor to be combined with this, a mercapto compound;
There are amine compounds, but amine compounds are generally preferred.

Examples of amine compounds include triethylamine,
Methylgetanolamine, triethanolamine, diethylaminoethyl (meth)acrylate, p-dimethylaminoacetophenone.

Examples include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, and 4,4'-bis(diethylamino)benzophenone. These photopolymerization initiators may be used alone or in combination of two or more.

In addition to the above, a polymerizable unsaturated compound having an acryloyl group may be blended regardless of the Tg value of the cured film. In particular, for the purpose of imparting tensile elongation to the cured film, it is preferable to use a polymerizable compound having an ethylenically unsaturated bond as shown below.

Examples Eva, vinyl caprolactam, N-vinyl-2-pyrrolidone, acryloylmorpholine, vinyl imitazole, vinyl-p-t-7'ylbenzoate, cyclohexyl acrylate, isobornyl acrylate, dicyclopentanyl acrylate, dicyclopentanyl acrylate, Examples include cyclopentenyl acrylate.

Further, as other additives, thermal polymerization inhibitors, antioxidants, plasticizers, silane coupling agents, etc. can be added for the purpose of improving various properties.

The polymerizable unsaturated compound, which is a compound having two or more acryloyl groups and whose single cured product has a glass transition temperature of 100°C or higher, is in the range of 20% to 80% by weight, preferably 30% to 80% by weight of the composition. The amount of polymerizable unsaturated polyurethane is 20 to 70% by weight, preferably 30 to 65% by weight. The photoinitiator is in the range 0.1-10 wt., especially 1
A range of 5% by weight is preferred. Other polymerizable compounds are preferably blended in an amount of 5 to 25% by weight.

Although it depends on the purpose, it is preferable to use the additive in a range of 1100 pp to 3% by weight.

[Effect]

Methods for measuring the glass transition temperature include dynamic viscoelastic analysis, differential scanning calorimetry, thermomechanical analysis, etc. In the present invention, dynamic viscoelastic analysis (hereinafter referred to as DMA) is used. .

In DMA, the complex elastic modulus E1 of the sample is measured, which is expressed by a so-called elastic modulus E in the real part and a term E attributable to the viscosity modulus in the imaginary part.

E” =Er+i E4 Furthermore, Ei/Er is called the loss rate tanδ, and ta
The temperature at which nδ reaches its maximum is the glass transition temperature.

FIG. 1 is a diagram showing the temperature characteristics of three compounds in terms of elastic modulus and tan δ. From this figure, T
It can be seen that the higher g is, the wider the temperature range in which the temperature dependence of the elastic modulus is large near Tg. That is, in order to reduce the temperature dependence of the elastic modulus of the cured film of the ultraviolet curable resin composition for coating optical fibers in the practical temperature range of 30°C to 60°C for optical fibers, it is necessary to set Tg to 1 in high-temperature examples.
The temperature must be 00℃ or higher, and on the low temperature side, Tg must be 14℃ or higher.
It is necessary that the temperature is below 0°C.

The tan δ of a cured film of an ultraviolet curable resin composition composed of multiple components is the tan δi of a single cured film of component i.
, the elastic modulus Ei and the weight concentration Ci, it can be calculated according to equation (1).

Here, n is the number of components in the composition that contribute to curing.

Equation (1) is a general equation, and it is thought that it is difficult to understand how the Tg of an actual cured film is predicted using only this equation, so a two-component system will be explained below as an example.

Figure 2 shows a case where the Tg of the first component is about 200°C and the second component is about -50°C, and the Tg is widely different. In a mixture system, the value changes somewhat. However, it can be seen that the Tg of each component is maintained, and the elastic modulus is almost constant regardless of temperature in the range of -50°C to 100°C.

Figure 3 shows tan δ in a two-component mixture system with close Tg.
The results of evaluation using equation (1) are shown. In this case, the Tg of the mixture system becomes one and is located between each component g. In this case, if the high Tg component is used as the main component, the Tg of the mixture system approaches the high Tg.

By considering the composition and formulation with reference to these examples, we can create an ultraviolet curable resin composition for coating optical fibers with a small temperature dependence of the elastic modulus in the practical temperature range of -30℃ to 60℃. I can make things.

〔Example〕

EXAMPLES Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

First, a synthesis example of the polymerizable unsaturated urethane of the present invention will be shown.

Polytetramethylene glycol (number average molecular weight 850)
1 mole and 2 moles of 2,4-tolylene diisocyanate were charged into a reaction vessel equipped with a nitrogen gas inlet tube, a stirrer, and a cooling tube, and reacted at 70° C. for 2 hours. Next, 2 moles of 2-hydroxypropyl acrylate and t-
A trace amount of butylhydroquinone and a trace amount of dibutyltin dilaurate as a catalyst were gradually added, and the reaction was further carried out at 70°C for 5 hours to obtain a polymerizable unsaturated polyurethane (A-1) having an acryloyl group.

Golden Bottom 11 In the same manner as Synthesis Example 1, except that in Synthesis Example 1, 1 mole of polypropylene glycol (number average molecular weight 2.000) was used instead of 1 mole of polytetramethylene glycol (number average molecular weight 850), A polymerizable unsaturated polyurethane (A-2) having an acryloyl group was obtained.

In the same manner as in Synthesis Example 1, except for using 1 mol of polypropylene glycol (number average molecular weight 3,000) instead of 1 mol of polytetramethylene glycol (number average molecular weight 850) in Kanazanuki main synthesis example 1, A polymerizable unsaturated polyurethane (A-2) having an acryloyl group was obtained.

Examples and comparative examples of the ultraviolet curable resin composition for coating optical fibers of the present invention are shown below.

50 parts by weight of polymerizable unsaturated polyurethane having acryloyl groups (A-3) obtained by Synthesis Example 3, Tris-2
- 30 parts by weight of hydroxyethyl isocyanurate triacrylate, 15 parts by weight of N-vinyl-2-pyrrolidone and 5 parts by weight of benzyl dimethyl ketal were mixed and dissolved at 60°C for 1 hour to form a liquid ultraviolet ray with a viscosity of 22 voids (25°C). A curable resin composition was obtained.

1 boat [1 40 parts by weight of the polymerizable unsaturated polyurethane (A-3) having acryloyl groups obtained in Synthesis Example 3, Tris-2-
Hydroxyethyl isocyanurate triacrylate 4
0 parts by weight, 15 parts by weight of N-vinyl-2-pyrrolidone, and 5 parts by weight of benzyl dimethyl ketal were mixed and dissolved at 60°C for 1 hour to obtain a liquid ultraviolet curable resin composition having a viscosity of 17 voids (25°C).

Example 1 60 parts by weight of the polymerizable unsaturated polyurethane (A-1) having an acryloyl group obtained in Main Synthesis Example 1, Tris-2-
Hydroxyethyl isocyanurate triacrylate 2
0 parts by weight, 15 parts by weight of N-vinyl-2-pyrrolidone, and 5 parts by weight of benzyl dimethyl ketal were mixed and dissolved at 60°C for 1 hour to obtain a liquid ultraviolet curable resin composition with a viscosity of 59 poise (25°C). .

35 parts by weight of the polymerizable unsaturated polyurethane (A-2) having an acryloyl group obtained in Step 11 Preparation Example 2, 150 parts by weight of tricyclodecane dimetatool diacrylate, 10 parts by weight of N-vinyl-2-pyrrolidone, and 5 parts by weight of benzyl dimethyl ketal were mixed and dissolved at 60°C for 1 hour to obtain a liquid ultraviolet curable resin composition having a viscosity of -19 poise (25°C).

Kitakan group: 55 parts by weight of the polymerizable unsaturated polyurethane (A-2) having an acryloyl group obtained in Synthesis Example 2, 30 parts by weight of tricyclodecane dimetatool diacrylate, and 10 parts by weight of N-vinyl-2-pyrrolidone. and 5 parts by weight of benzyl dimethyl ketal were mixed and dissolved at 60°C for 1 hour to obtain a viscosity of 6.
A liquid ultraviolet curable resin composition of 3 poise (25° C.) was obtained.

Table 1 shows the compositions and physical properties of Production Examples 1 to 6, Examples 1 to 4, and Comparative Example 1. The numbers shown in the composition column are the blended amounts, and the blended amounts are shown in parts by weight.

The compositions of Preparation Examples 1 to 6 were prepared by mixing each component and heating at 60°C for 1
A homogeneous composition was created by stirring for a period of time.

Next, methods for measuring the physical properties listed in the physical properties column of Table 1 will be shown.

Garth - Each composition was coated on a glass plate with a film thickness of 50 ± 10μ,
Using a metal halide lamp (lamp output 2 -),
A film-like sample with a film thickness of 5°±10 μm was prepared by irradiating 20 mJ/e+” of ultraviolet light.

The loss rate of the ultraviolet cured film of each composition was measured using a dynamic viscoelasticity measurement device, Rheoviplon DDV-I [EA type (■Orientik Co., Ltd.)], and the temperature that gave the maximum value of the loss rate was determined as the glass transition temperature. did.

A No. 2 type test piece was prepared from the ultraviolet-cured film of each composition with a film thickness of 50 ± 10 μm obtained by the method described in "Method for measuring glass transition temperature" of Toyoji-no-Matsu plate fixed removal, and JIS K 7113. The elastic modulus was measured according to the following. However, the tensile rate was 4% strain/min, and the elastic modulus was calculated from the tensile stress at 2.5% strain.

Examples 1 and 2 are a polymerizable unsaturated polyurethane having an acryloyl group whose glass transition temperature is 140°C or less in the mixture with a photopolymerization initiator, and a glass transition temperature of the homopolymer is 100°C or higher. The glass transition temperature of the UV-cured film of the UV-curable resin composition for coating optical fibers, which is composed of a compound having two or more acryloyl groups in the molecule and a polymerizable compound having an ethylenically unsaturated bond, is -40''C. The composition below and above 100°C are shown below.The ultraviolet cured film of this composition
The ratio of elastic modulus at ℃ and 60℃ is 2.7 and 2.5,
It can be seen that the temperature dependence of the elastic modulus in the practical temperature range is extremely small.

In Examples 3 and 4, the glass transition temperature of the homopolymer was 14
Polymerizable unsaturated polyurethane having an acryloyl group and a homopolymer having a glass transition temperature of 100°C or less
The glass transition temperature of the UV-cured film of the UV-curable resin composition for coating optical fibers, which is composed of the above compound having two or more acryloyl groups in one molecule and the polymerizable compound having an ethylenically unsaturated bond, is 100°C or higher. The composition shown in FIG. The ratio of the elastic modulus of the ultraviolet cured film of this composition at 30° C. and 60° C. is 467 and 3.8, indicating that the temperature dependence of the elastic modulus in the practical temperature range is small.

Comparative Example 1 is an ultraviolet curable resin composition for coating optical fibers consisting of the same components as in Example 4, but since the glass transition temperature of the ultraviolet curable film of this composition is 100°C or less, the composition was heated at -30°C. The ratio of the elastic modulus at 60° C. and 60° C. was 7.8, which indicates that the elastic modulus has a large temperature dependence in the practical temperature range and is not preferred as an ultraviolet curable resin composition for coating optical fibers.

〔Effect of the invention〕

The ultraviolet curable resin composition for coating optical fibers of the present invention includes:
Since the temperature dependence of the elastic modulus in the practical temperature range of 30° C. to 60° C. is small, an optical fiber coated with this composition has the great feature of having small fluctuations in optical signal transmission loss caused by environmental temperature changes.

[Brief explanation of drawings]

FIG. 1 is a chart showing the temperature characteristics of the elastic modulus and loss rate of the ultraviolet-cured films of the compositions of Preparation Examples 1, 3, and 5. Figure 2 shows the temperature of the elastic modulus and loss rate of the UV-cured film for each of the first component with rg of about 200°C, the second component with rg of about 50°C, and a mixture of equal amounts of the first and second components. This is a chart showing the characteristics. Figure 3 shows the third component, fourth component, and third component whose Tg is close to each other.
It is a chart showing the temperature characteristics of the elastic modulus and loss rate of each ultraviolet-cured film of a mixture of equal amounts of the component and the fourth component.

Claims (1)

[Claims] 1. Contains (1) a polymerizable unsaturated compound having two or more acryloyl groups whose homopolymer has a glass transition temperature of 100°C or higher, and (2) a photopolymerization initiator. An ultraviolet curable resin composition for coating optical fibers. 2. (1) A polymerizable unsaturated compound having two or more acryloyl groups whose homopolymer has a glass transition temperature of 100°C or higher, (2) (a) a hydroxy compound having a polyoxyalkylene block, (b) acryloyl An ultraviolet curable resin composition for coating an optical fiber, comprising a polymerizable unsaturated polyurethane obtained by reacting a hydroxy compound having a group and (c) a polyisocyanate, and (3) a photopolymerization initiator. 3. Claim 2, characterized in that the homopolymer of polymerizable unsaturated polyurethane has a glass transition temperature of -40°C or lower.
The ultraviolet curable resin composition for coating an optical fiber as described above. 4. The glass transition temperature of the film cured with ultraviolet light is -40
The ultraviolet curable resin composition for coating an optical fiber according to claim 1 or 2, which has a temperature in the range of 100°C or lower. 5. The optical fiber according to claim 1, 2, 3 or 4, wherein the value obtained by dividing the tensile modulus measured at -30°C of the film cured by ultraviolet rays by the tensile modulus measured at 60°C is 5 or less. UV-curable resin composition for coating.