JPS62158142A - Clad material for optical glass fiber - Google Patents

Abstract

PURPOSE:To obtain the titled clad material having superior curability and providing high toughness of the cured product by mixing a specified urethane (meth)acrylate oligomer, a liquid compd. having low viscosity, and a polymn. initiator. CONSTITUTION:The clad material consists of (a) urethane (meth)acrylate oligomer contg. oligomer having (meth)acryloyl groups at both terminals of the molecule obtd. by the reaction of a mixture of polyoxy tetramethylene glycol and bisphenol type alkylene oxide adduct with a diisocyanate compd. and hydroxyalkyl (meth)acrylate, (b) a liquid compd. having low viscosity at room temp. contg. >=one polymerizable C=C double bond in a molecule which functions as reactive diluent of the above described component (a), and (c) a polymerization initiator. Preferred polymn. initiator (c) is such photopolymn. initiator capable of causing setting of the clad material quickly by the irradiation with ultraviolet rays.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to materials for coating optical glass fibers for light transmission.

[Conventional technology]

Optical glass fibers (hereinafter simply referred to as optical fibers) used as optical transmission media usually have a diameter of 20 mm.
Since it is less than 0 μm and the material is brittle, scratches are likely to occur on the surface during manufacturing, cable production, and storage, and these scratches become a source of stress concentration, making it easy to damage when external stress is applied. The disadvantage is that the optical fiber may break.

For this reason, it is extremely difficult to use optical fiber as it is as a medium for optical transmission. Therefore, conventionally, attempts have been made to coat the surface of an optical fiber with a resin, thereby maintaining the initial strength immediately after manufacturing the optical fiber and producing an optical fiber that can withstand long-term use.

Examples of such resin coating materials include those using thermosetting resins such as silicone resin, epoxy resin, and urethane resin, and those using ultraviolet rays such as epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate. Those using curable resin are known.

[Problem that the invention seeks to solve]

However, the above-mentioned thermosetting materials require a long time to cure and dry, resulting in poor productivity for optical fibers, and lack of long-term reliability due to insufficient curing, which impairs the adhesion between the coating and the optical fiber. I don't like it. Furthermore, although the above-mentioned UV-curable materials exhibit relatively good curability, it is generally difficult to satisfy both elongation and mechanical strength such as tensile strength and tensile modulus of the cured product, and these comprehensive evaluations are difficult to achieve. There is a problem in that the toughness of the cured product is inferior as determined by the process, and this has been one of the causes of lowering the reliability of optical fibers.

Therefore, the present invention solves the above conventional problems and improves the productivity of optical fibers with excellent curability.
Furthermore, the present invention aims to provide an industrially useful coating material for optical fibers that has excellent toughness as a cured product and greatly contributes to improving the reliability of optical fibers.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors have developed a coating material for optical fibers using a urethane (meth)acrylate oligomer derived from a mixed glycol of polyoxytetramethylene glycol and a bisphenol-based alkylene oxide adduct. When used as the main material for optical fibers, it can be quickly cured by heating or irradiating with ultraviolet rays or electron beams after being applied to the surface of the optical fiber, and the cured product is strong with both elongation and mechanical strength. This invention was realized based on the knowledge that the fiber has excellent properties and greatly contributes to improving the long-term reliability of optical fibers.

That is, the present invention provides (meth)acryloyl groups at both ends of a molecule obtained by reacting a) a mixture of polyoxytetramethylene glycol and a bisphenol-based alkylene oxide adduct, a diisocyanate compound, and a hydroxyalkyl meth)acrylate. b) a urethane (meth)acrylate oligomer containing as an essential component an oligomer having polymerizable carbon-
The present invention relates to an optical fiber coating material characterized by containing a compound containing one or more carbon double bonds and having a low viscosity in liquid form at room temperature, and C) a polymerization initiator.

In addition, in this specification, the (meth)acryloyl group refers to an acryloyl group and/or a methacryloyl group,
(Meth)acrylate means acrylate and/or methacrylate, respectively.

In addition, the number average molecular weight described in this specification refers to a value measured by gel permeation chromatography (GPC) using polystyrene as a standard, and viscosity refers to a value measured by a Brookfield viscometer. , respectively.

[Structure and operation of the invention]

The urethane (meth)acrylate oligomer as component a used in this invention is obtained by reacting a diisocyanate compound and a hydroxyalkyl (meth)acrylate with a mixture consisting of polyoxytetramethylene glycol and a bisphenol alkylene oxide adduct. The resulting molecule contains an oligomer having (meth)acryloyl groups at both ends as an essential component.

The above-mentioned specific oligomer has excellent curability, and also has good flexibility derived from the polyoxytetramethylene glycol skeleton and good hardness and strength derived from the bisphenol-based alkylene oxide adduct, so it can be used alone to elongate. It has the characteristic of providing a cured product having good toughness that satisfies both mechanical strength and mechanical strength.

As the polyoxytetramethylene glycol for obtaining such a specific oligomer, one having a number average molecular weight in the range of 500 to 2,000 is preferably used. In addition, as a bisphenol-based alkylene oxide adduct used in combination with this, an alkylene oxide is added to a bisphenol, for example, the following formula;
(R, , R2 are hydrogen or methyl groups, R, , R4 are alkylene groups, n is an integer of 1 to 20), and those having a number average molecular weight of usually about 300 to 5,000 are preferably used.

In the above formula, R and R are fullylene oxides having generally 2 to 4 carbon atoms, such as ethylene oxide and propylene oxide, and the number of moles n added is determined by the reaction operation for homogeneous reaction with diisocyanate compounds, etc. From the viewpoint of elongation and toughness of the cured product, it is desirable to select from the range of 1 to 20, particularly from the range of 2 to 15.

The mixing ratio of polyoxytetramethylene glycol and bisphenol-based alkylene oxide adduct affects the elongation and mechanical strength of the cured product, so it is appropriately determined depending on the actual use of the optical fiber. Generally, the molar ratio of polyoxytetramethylene glycol and bisphenol alkylene oxide adduct is 0.9:0.
1, particularly preferably within the range of 0°85:0.15.

In addition, the diisocyanate compound to be reacted with the above glycol mixture has a molecular weight of about 170 to 1,006, and specifically, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, bis(isocyanatemethyl)cyclohexane , dicyclohexylmethane diisocyanate, 1,6-hexane diisocyanate, and the like. Also, hydroxyalkyl (
As the meth)acrylate, 2-hydroxyethyl (
meth)acrylate, 2-hydroxypropyl(meth)
Those having a hydroxyalkyl group usually having about 2 to 4 carbon atoms, such as acrylate, are used.

The specific oligomer in this invention has (meth)acryloyl groups at both ends of the molecule by reacting the above-mentioned glycol mixture, diisocyanate compound, and hydroxyalkyl (meth)acrylate. For example, the above three components may be reacted at once, or the glycol mixture may be reacted with a diisocyanate compound first and then with a hydroxyalkyl (meth)acrylate.

In the above reaction, by appropriately setting the molar ratio of the glycol mixture and the diisocyanate compound and adjusting the number of repeating structural units n consisting of a urethane structure,
The number average molecular weight of the oligomer having (meth)acryloyl groups at both ends of the molecule is 1,000 to 5.
It is preferable to set it within the range of 000. In addition, n-1
In this case, the molar ratio is approximately 2 moles of the diisocyanate compound to 1 mole of the glycol mixture.

Further, in these reactions, an appropriate reaction solvent may be used if necessary. As the reaction solvent, a general solvent that can be removed after the reaction may be used, but it is preferable to use component b described later as the solvent for the above reaction. In the latter case, the reaction product can be used as it is as a raw material component for the coating material of the present invention without going through the step of successively removing the solvent after the reaction.

In this invention, the specific oligomer having (meth)acryloyl groups at both ends of the molecule obtained in this way can be used alone as the urethane (meth)acrylate oligomer of component a, as described above. However, other urethane (meth)acrylate oligomers may be used in combination with the above-mentioned specific oligomers in order to slightly adjust the elongation characteristics, mechanical strength, etc. of the cured product.

Urethane (meth)acrylate oligomers that can be used in combination include general polyether urethane (meth)acrylates derived from polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, etc., other polyester urethane (meth)acrylates, and polycarbonate urethanes. Examples include (meth)acrylates having a number average molecular weight of about 700 to 10,000. Urethane (meth) that can be used in combination with this
The amount of the acrylate oligomer to be used may be appropriately determined depending on the intended use within a range of 85% or less based on the total amount with the specific oligomer.

The optical fiber coating material of the present invention is a urethane (meth)acrylate oligomer made of such a C component,
As component B, a compound containing one or more polymerizable carbon-carbon double bonds in one molecule and which is liquid at room temperature and has a low viscosity is blended, which acts at least as a reactive diluent for the oligomer, and as component C. It is obtained by adding a polymerization initiator.

The above component b is used to adjust the viscosity of the coating material and improve workability when coating the optical fiber, since the urethane (meth)acrylate oligomer is usually solid or highly viscous at room temperature. At the same time, it acts as an effective component for adjusting the flexibility and hardness of the cured film.

As the b component, a compound having one or more polymerizable carbon-carbon double bonds, preferably 1 to 3 polymerizable carbon-carbon double bonds in the molecule and which is a low viscosity liquid at room temperature is used. is 2 to 2,000 centimeters/25'C
It refers to something within a range of degrees.

This compound is not limited to one type, but two or more types can be used in combination,
When used in combination, it is sufficient that the properties of the mixture are as described above. Therefore, one of them may be solid or have high viscosity at room temperature.

The molecular weight of this b component is usually 150 to 1,000.
That's about it.

Specific examples of the above-mentioned components include those containing a (meth)acryloyl group as a polymerizable carbon-carbon double bond, such as 2
- Ethylhexyl (meth)acrylate, tetrahydrofurfuryl alcohol caprolactone adduct (meth)
Acrylate, (meth)acrylate of nonylphenol ethylene ogicide adduct, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, bisphenol diethylene glycol di(meth)acrylate, hydrogenated bisphenol triethylene glycol di(meth)acrylate, Examples include mono- and poly(meth)acrylates such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate.

In addition, the above-mentioned components include allyl esters such as diallyl adipate, diallyl phthalate, triallyl trimellitate, and triallyl isocyanurate, styrene, vinyl acetate, N-vinylpyrrolidone, N-N-dimethylacrylamide, N・N-dimethyl Vinyl compounds such as aminopropylacrylamide and N-N-dimethylaminoethyl acrylate can also be used.

The amount of the above-mentioned components to be used can be selected as appropriate depending on the properties of component C and the desired characteristics of the cured product, as well as the type of component b itself. Generally, it is preferable that the proportion of the b component in the total amount of the C component and the b component is about 30 to 60%, and in this case, the proportion of the above-mentioned specific component in the total amount The proportion of the oligomer, that is, the specific oligomer derived from the mixture of polyoxytetramethylene glycol and bisphenol-based alkylene oxide adduct, is usually 40 to 70% by weight, preferably 5% by weight.
It is desirable that the content of J and S be 0 to 60% by weight.

In this invention, the polymerization initiator used as component C is preferably a photopolymerization initiator that can quickly cure the coating material by irradiation with ultraviolet rays. Various types of sensitizers can be used. For example, benzoin, hengeine methyl ether, hengeine ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, hensyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methyl anthraquinone, Toxyacetophenone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxane, anthracene, 1,1-dichloroacetophenone, methylorthobenzoylbenzoate, etc., and small amounts of sensitizing aids such as these and amines. Examples include those used in combination with.

Further, as the above polymerization initiator, it is also possible to use a thermal polymerization initiator, and specific examples thereof include peresters such as tertiary butyl peroctoate and tertiary butyl pervivalate, bis-(4-tertiary (butylcyclohexyl)-peroxydicarponate, diacyl peroxides such as benzoyl peroxide, dialkyl peroxides such as di-tert-butyl peroxide and dicumyl peroxide, cyclohexanone peroxide,
Hydroperoxides such as methyl ethyl ketone peroxide and cumene hydroperoxide, and 2-
Examples include peroxide polymerization initiators such as those in combination with metal promoters such as cobalt-II salts of ethylhexanoic acid and naphthenic acid, and other azo compounds can also be used.

The amount of these polymerization initiators added is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the total amount of component C and component B. If this amount is too small, the curability cannot be satisfied, and even if it is used in excess of a predetermined amount, no further improvement in the curing rate can be expected.

The optical fiber coating material of the present invention includes the above C components, b
component and C component are essential components, and if necessary, various modifying resins such as acrylic resin, polyamide resin, polyester resin, polyether resin, polyurethane resin, polyamideimide resin, silicone resin, phenol resin, and organic Various additives such as silicon compounds and surfactants may be added, and the overall viscosity is usually adjusted within the range of 1,000 to 10,000 centivoise (25°C) from the viewpoint of coating workability. It is desirable to have one.

Rather than applying the coating material of the present invention having such a structure directly to the surface of the optical fiber, it is usually possible to apply a coating for the inner layer, which is softer than this material, and then coat it as an outer layer on this material. It is desirable to do so. The coating thickness at this time is usually 50 to 400 μm after curing, and after this coating, depending on the type of polymerization initiator, it may be cured by heating or irradiated with ultraviolet rays or electron beams. All you have to do is harden it.

Furthermore, by further forming a tough coating such as a thermoplastic resin coating such as polyethylene or nylon as the outermost layer on the coating layer thus formed, the optical fiber coating with even better fiber strength can be achieved. It can be a body.

〔Effect of the invention〕

As described above, in this invention, by using the specific urethane (meth)acrylate oligomer as the C component as the main material of the coating material, it has good curability and can contribute to improving the productivity of optical fibers. In addition, it is possible to provide an industrially useful optical fiber coating material that has good toughness that satisfies both elongation and mechanical strength of the cured product and greatly contributes to improving the long-term reliability of optical fibers. can.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example ■ 55.3 g (0°085 mol) of polyoxytetramethylene glycol having a number average molecular weight of 650 was placed in a 300 cc four-bottle flask equipped with a stirrer, a condenser, and a thermometer.
Add 5.9 g (0.015 mol) of bisphenol A propylene oxide adduct with a number average molecular weight of 396, 34.8 g (0.2 mol) of tolylene diisocyanate, and 0.02 g of dibutyltin dilaurate, and heat at 70°C. After reacting for 3 hours at
By reacting at C for 5 hours, an oligomer having acryloyl groups at both ends of the molecule was obtained.

Next, 50 parts of bisphenol F diethylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylaminoethanol were blended with 50 parts of this oligomer, mixed and dissolved to give a viscosity of 8,300 centiboise (at 25°C).
) coating material for optical fiber was obtained.

Example 2 The amount of polyoxytetramethylene glycol used was 45.
Example 1 was carried out in exactly the same manner as in Example 1, except that the amount of bisphenol A propylene oxide adduct was changed to 11.9 g (0.03 mol), and the amount of bisphenol A propylene oxide adduct was changed to 11.9 g (0.03 mol). (25° C.) An optical fiber coating material was obtained.

Example 3 The amount of polyoxytetramethylene glycol used was 32.
5g (0.05 mol) and bisphenol A
5.9 g of propylene oxide adduct (7) The viscosity 12,500
A centiboise (25° C.) optical fiber coating material was obtained.

Comparative Example 1 In a reaction vessel similar to that in Example 1, 39.6% of the same bisphenol A propylene oxide adduct as in Example 1 was added.
g (0.1 mol), tolylene diisocyanate 34.8
g (0.2 mol), 23.2 g (0.2 mol) of 2-hydroxyethyl acrylate, 0.02 g of dibutyltin dilaurate, and 98 g of bisphenol F diethylene glycol diacrylate as a reaction solvent were added.
By reacting at °C for 8 hours, a reaction product containing an oligomer having acryloyl groups at both ends of the molecule and the above reaction solvent was obtained.

Next, 100 parts of this reaction product was added with 3 hensifenones.
1 part of diethylaminoethanol and 1 part of diethylaminoethanol were mixed and dissolved well to obtain a viscosity of 17,200 centiboise (at 25°C).
) coating material for optical fiber was obtained.

Comparative Example 2 Into the same reaction vessel as in Example 1, 65°0 g of polyoxytetramethylene glycol (0,1
mol), tolylene diisocyanate 34.8g (0,2
mole), 2-hydroxyethyl acrylate) 23.2g
(0.2 mol) and dibutyltin dilaurate 0.0
By adding 2g and reacting at 70°C for 8 hours,
An oligomer having acryloyl groups at both ends of the molecule was obtained.

Next, 50 parts of bisphenol F diethylene glycol diacrylate, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added to 50 parts of this oligomer, and mixed and dissolved to give a viscosity of 7,700 centiboise (at 25°C).
) coating material for optical fiber was obtained.

In order to investigate the performance of each optical fiber coating material of Examples 1 to 3 and Comparative Example 1.2, the following tests were conducted.

Test Example 1 After applying each coating material to a thickness of 0.25 m on a glass plate, it was cured using a high-pressure mercury lamp (80w/cm), and the amount of ultraviolet irradiation required for complete curing and the amount of cured film were determined. The results of Shore hardness, tensile strength, tensile modulus and elongation are shown in the table below. The tensile strength, tensile modulus and elongation are as per JIS K711.
The test was carried out in accordance with 3.

Test Example 2> As inner layer materials, 50 parts of urethane acrylate oligomer of polyoxytetramethylene glycol (number average molecular weight FF 12.000) and 45 parts of acrylate of tetrahydride-furfuryl alcohol caprolactone adduct were applied to the surface of an optical fiber with a diameter of 125 μm. 1 part, N-vinylpyrrolidone 5 parts, benzophenone 3 parts, and diethylaminoethanol 1 part. hardened with.

Thereafter, each of the optical fiber coating materials of Examples 1 to 3 and Comparative Example 1.2 was applied as an outer layer so that the diameter after coating was 400 μm, and the same high-pressure mercury lamp as above was used. It was cured at the same speed as above.

The optical fiber coated body thus obtained was prepared in Example 1.
Those using the coating materials of Comparative Examples 1 and 3 had good bobbin winding characteristics and lateral pressure characteristics, but those using the coating materials of Comparative Examples 1 and 2 were inferior in both of the above characteristics, and the transmission loss was poor. A rapid increase was observed.

Note that the bobbin winding characteristics are the results obtained by examining the increase in transmission loss when the bobbin is wound on a drum with a diameter of 30 cm (tension: 80 g), and the lateral pressure characteristics are the results obtained by examining the increase in transmission loss when winding a bobbin on a drum with a diameter of 30 cm (tension: 80 g). The increase in transmission loss is calculated by sandwiching the length and applying a load from above three times.

Claims (1)

[Claims] (1)a) An oligomer having (meth)acryloyl groups at both molecular ends obtained by reacting a mixture consisting of polyoxytetramethylene glycol and a bisphenol-based alkylene oxide adduct, a diisocyanate compound, and a hydroxyalkyl (meth)acrylate. urethane (meth)acrylate oligomer containing as an essential component, b) having at least one polymerizable carbon-carbon double bond in one molecule, which acts as a reactive diluent for component a above;
1. A coating material for an optical glass fiber, comprising: a compound that is liquid at room temperature and has a low viscosity; and c) a polymerization initiator.