JPS63144150A - Coating material for optical glass fiber - Google Patents

Abstract

PURPOSE:To obtain the titled tough material having a high curing rate and elastic modulus as well as large elongation, by additionally containing a specific curable component in an ultraviolet curing type material consisting essentially of urethane (meth)acrylate oligomer. CONSTITUTION:The titled material obtained by additionally containing (D) an ester of a hydantoin type diol with (meth)acrylic acid, e.g. reactive product of 1,3-di-(2-hydroxyethyl)-5,5-dimethylhydantoin with acrylic acid, etc., as a curable component to an ultraviolet curing type material containing (A) urethane (meth)acrylate oligomer, (B) a compound which is a low-viscosity liquid at ordinary temperature and has one or more polymerizable carbon-carbon double bonds in one molecule as a reactive diluent for the component (A), e.g. bisphenol diethylene glycol dicacrylate, etc., and (C) a photoinitiator. Further addition of the component (D) to conventionally known materials consisting of the components (A), (B) and (C) provides the titled material, having a high curing rate and curable into tough articles with a great elongation and high elastic modulus.

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]

The resin coating of optical glass fibers (hereinafter referred to as optical fibers) is usually coated with a secondary coating for an inner layer with good flexibility such as silicone rubber, and then a secondary coating for a strong outer layer with a high tensile modulus that stretches on top of that. Covered. Conventionally, UV-curable materials with fast curing speed have been mainly used as secondary coating materials for the outer layer, and typical examples include:
Main material is urethane (meth)acrylate oligomer,
It is known that a reactive diluent and a photopolymerization initiator are added to this.

[Problem that the invention seeks to solve]

However, the conventional UV-curable materials based on urethane (meth)acrylate oligomers, which are known as secondary coating materials, cannot be said to be fully satisfactory in terms of toughness of the cured product, especially Since the elastic modulus is low, there is a problem that there is no resistance to lateral pressure, and the curing speed is rather slow.

Therefore, the present invention solves the above-mentioned conventional problems and improves the productivity of optical fibers by increasing the curing speed.
In addition, the cured product has a high elongation and a high elastic modulus, and is an industrially useful coating for optical fibers that can prevent an increase in transmission tM loss due to insufficient toughness and greatly contributes to improving the reliability of optical fibers. The purpose is to provide materials.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that when using a conventional ultraviolet curable material mainly composed of urethane (meth)acrylate oligomer, a specific compound is further used as a curable component. The inventors discovered that it was possible to obtain a coating material for optical fibers that cured quickly and could provide a strong cured product with high elongation (and high modulus of elasticity), leading to the completion of this invention.

That is, the present invention provides a urethane (meth)acrylate oligomer, b) a urethane (meth)acrylate oligomer, b) containing at least one polymerizable carbon-carbon double bond in one molecule that at least functions as a reactive diluent for component a. A coating material for an optical fiber containing a compound that is liquid with low viscosity at room temperature and C) a photopolymerization initiator, which in addition to the above components a, b, and c, contains d) an ester of a hydantoin diol and (meth)acrylic acid. The present invention relates to a coating material for optical fiber, which is characterized by having a

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, and (meth)acrylic acid means acrylic acid and/or methacrylic acid, respectively.

In addition, the number average molecular weight (hereinafter referred to as MW) 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 using a Brookfield viscometer. shall mean the values measured by, respectively.

[Structure and operation of the invention]

The urethane (meth)acrylate oligomer as component a used in this invention has a urethane bond in its molecular skeleton, and has two or more (meth)acryloyl groups, usually up to six, in the molecule, and generally has a MW of 500. ~10
,000, which broadly includes conventionally known urethane (meth)acrylates. Specific examples include urethane (meth)acrylate oligomers such as polyether, polyester, polycaprolactone, and polycarbonate.

These urethane (meth)acrylate oligomers are
Compared to other (meth)acrylate oligomers used in ultraviolet curable materials, the cured product has a large elongation and a relatively good tensile modulus. However, by simply combining this oligomer with a reactive diluent as component b, it is difficult to increase both elongation and tensile modulus and provide excellent toughness. There are some difficulties. Therefore, in the present invention, a specific curable component as the d component, which will be described later, is used in combination to improve the above characteristics.

The above urethane (meth)acrylate oligomer can be produced by using, for example, a polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, etc. as a polyol component, and reacting these polyols with a diisocyanate compound and further with a hydroxyalkyl (meth)acrylate. can be obtained by

Examples of the above diisocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, knack diisocyanate, isophorone diisocyanate, bis(isocyanate methyl)cyclohexane, dicyclohexylmethane diisocyanate, and 1,6-hexane diisocyanate, each having a molecular weight of 100 to 1,000.
Various compounds of about 0 are used. Moreover, as the above-mentioned hydroxyalkyl (meth)acrylate, those having a hydroxyalkyl group having about 2 to 5 carbon atoms, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate, are used.

Since the urethane (meth)acrylate oligomer of component a is usually solid or highly viscous at room temperature, the compound used as component b, which is liquid at room temperature, used in this invention is made by adjusting the viscosity as a coating material. It is used to improve workability during fiber coating, but it also acts as an effective component to adjust 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 6 polymerizable carbon-carbon double bonds in the molecule and which is a low viscosity liquid at room temperature is used. is in the range of about 2 to 2,000 centivoices/25°C.

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

The molecular weight of component b is usually about 90 to 2.000.

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

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 ester as the d component used in this invention is:
A hydantoin type diol and (meth)acrylic acid are usually used as a catalyst in an acidic compound such as hydrochloric acid, sulfuric acid, or p-toluenesulfonic acid in an amount of 0.1 to 10% by weight, preferably 0.5 to 10% by weight.
A compound containing two (meth)acryloyl molecules in the molecule, obtained by using about 5% by weight and carrying out an esterification reaction at 80-120°C for 5-20 hours in the presence of a polymerization inhibitor such as hydroquinone if necessary. It is a compound containing a group.

The above-mentioned hydantoin-type diol is a diol derived from hydantoin or its substituted product, and a typical example thereof is an addition reaction of ethylene oxide or propylene oxide to hydantoin substituted with an alkyl group at the 5-5 position. There is a di(hydroxyalkyl)hydantoin represented by the following formula.

I error 0 = CN-(CHt-CH-0), H (wherein R1 and Rz are hydrogen or methyl group, respectively, R3,
Ra is an alkyl group having 1 to 5 carbon atoms, or a pentamethylene group whose side groups together form a cyclohexane ring with the 5th carbon of the hydantoin;
, n is an integer of 1 to 4, respectively) When used in combination with the a and b components, such an ester containing a (meth)acryloyl group in the molecule as the d component improves the elongation of the cured product. It greatly contributes to improving the tensile modulus and enhances toughness, and also contributes to improving curability and significantly speeds up the curing rate by ultraviolet irradiation.

In this invention, the above-mentioned components a, b, and d are used as curable components, and the proportion of each component is 150 to 90% by weight in total of components a and b, preferably 6% by weight.
d component is 50 to 10% by weight relative to 0 to 80% by weight,
The content is preferably 40 to 20% by weight. If the d component is too small, the above-mentioned effects cannot be expected, and if it is too large, the elongation may gradually decrease. In addition,
The mutual ratio of components a and b can be set as appropriate from the viewpoint of cured product properties and coating workability depending on the type of each component. Generally, in the total amount of a, b, and d components, the a component is 3
The proportion is preferably 0 to 70% by weight.

As the photopolymerization initiator used as component C in this invention, various kinds of initiators and sensitizers that are generally used as initiators and sensitizers for ultraviolet curable coatings can be used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-methylbenzoin, benzophenone, Michler's ketone, benzyl, benzyl dimethyl ketal, benzyl diethyl ketal, anthraquinone, methylanthraquinone, 2,2-jethoxyacetophenone, Examples include 2-methylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, anthracene, 1,1-dichloroacetophenone, methylorthobenzoylbenzoate, and those used in combination with small amounts of sensitizing aids such as amines. be able to.

The amounts of these photopolymerization initiators used include a, b,
Usually 0.1 to 10 parts by weight per 100 parts by weight of the total amount of component d.
The amount is about 1 to 5 parts by weight, preferably 1 to 5 parts by weight. 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-mentioned a.

It contains component C in the above ratio along with components b and d, which further contains acrylic resin, polyamide resin, polyester resin, polyether resin, polyurethane resin, polyamideimide resin, silicone resin, Various modifying resins such as phenol resins, and various additives such as organic silicon compounds and surfactants may be added, and the overall viscosity is usually 1°000 to 10.0° from the viewpoint of coating workability. 000 centiboise (cps)
) (25°C).

The optical fiber coating material of the present invention having the above-mentioned structure is usually coated on the surface of the optical fiber with an inner layer coating that is softer than this material, and then coated thereon as an outer layer. The coating thickness at this time is preferably such that the thickness after curing is usually about 50 to 300 μm.
After this coating, it may be cured by irradiating light such as ultraviolet rays. The irradiation amount is generally about 50 to 300 mJ/cd,
It has the characteristic that it can be cured much faster than conventional UV-curable materials.

Furthermore, by 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,
An optical fiber coating with even better fiber strength can be obtained.

〔Effect of the invention〕

As described above, in this invention, urethane (meth)
By including the specific compound as the d component in the optical fiber coating material that uses acrylate oligomer as the main component, the curing speed is fast and contributes to improving the productivity of optical fibers, and the cured product It has a high elongation and tensile modulus, has excellent toughness and flexibility, and has little increase in transmission loss due to lack of toughness. Therefore, it is extremely useful industrially as it greatly contributes to improving the long-term reliability of optical fibers. A coating material for optical fiber can be provided.

〔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 1 1,3-di(2-hydroxyethyl)-5,5-dimethylhydantoin [R+, Rz=hydrogen, R,
, R, = methyl group, m, n-1 di-ol] 1 mole and 2 moles of acrylic acid, P-) 5 parts of luenesulfonic acid, 0.01 part of hydroquinone, and an amount of benzene that can remove the produced water. After reacting at 90 to 110°C for 15 hours in the presence of ester A, it was washed with water, and benzene was removed under reduced pressure to obtain an ester containing two acryloyl groups in the molecule (hereinafter referred to as ester A).
) was obtained.

Next, polytetramethylene glycol (MWl, 00
0), tolylene diisocyanate, and 2-hydroxyethyl acrylate, 20 parts of the above ester A, 20 parts of bisphenol diethylene glycol diacrylate, 10 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol were added. Mix and dissolve, viscosity 5.1
00 cps (25° C.) of an optical fiber coating material was obtained.

Comparative Example 1 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate used was 40 parts,
Viscosity 3.500 cps as in Example 1
(25° C.) An optical fiber coating material was obtained.

Example 2 Urethane acrylate oligomer 5 synthesized from polycaprolactone diol (MW 2.000), tolylene diisocyanate, and 2-hydroxyethyl acrylate
0 parts, 30 parts of ester A obtained in Example 1, 10 parts of bisphenol diethylene glycol diacrylate, 10 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol were mixed and dissolved to give a viscosity of 6.800 cp.
A coating material for optical fiber was obtained.

Comparative Example 2 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate used was 40 parts,
In the same manner as in Example 2, the viscosity was 5.000 cps (2
A coating material for optical fiber was obtained.

Example 3 Polyester polyol (MWI, 000) synthesized from ethylene glycol and adipic acid, 40 parts of urethane acrylate oligomer synthesized from tolylene diisocyanate and 2-hydroxyethyl acrylate, 40 parts of ester A obtained in Example 1, bisphenol 10 parts of diethylene glycol diacrylate, vinylpyrrolidone ILa (S), 3 parts of benzophenone, and 1 part of diethylaminoethanol were mixed and dissolved to give a viscosity of 3.900 cps (2
A coating material for optical fiber was obtained.

Example 4 Instead of 1,3-di(2-hydroxyethyl)-5,5-dimethylhydantoin, l,3-di(2-hydroxyethyl)-5,5-pentamethylenehydantoin [R in the above formula] ,, Rt = hydrogen, R,, R, = pentamethylene group whose side groups together form a cyclohexane ring with the 5-position carbon of hydantoin, m, n-1 diol] were used in the same amount. An ester (hereinafter referred to as ester B) was obtained in the same manner as in Example 1.

An optical fiber coating material with a viscosity of 4500 cps (25°C) was obtained using the same formulation as in Example 3, except that the same amount of ester B was used instead of ester A in Example 3. Ta.

Example 5 Instead of 1,3-di(2-hydroxyethyl)-5,5-dimethylhydantoin, 1,3-di(2-hydroxypropyl)-5,5-diethylhydantoin [R+ in the above formula, An ester (hereinafter referred to as ester C) was obtained in the same manner as in Example 1, except that the same amounts of Rz-methyl group, R3, R4 = ethyl group, m and n-1 diols were used.

An optical fiber coating material with a viscosity of 4.500 cps (25°C) was obtained using the same formulation as in Example 3, except that the same amount of the above ester C was used instead of ester A in Example 3. .

Comparative Example 3 Except that Ester A was not used and the amount of bisphenol diethylene glycol diacrylate used was 50 parts,
In the same manner as in Example 3, the viscosity was 2,300 cps (2
A coating material for optical fiber was obtained.

<Test Example 1> After applying each coating material to a thickness of 0.2 tm on a glass plate, it was cured using a high-pressure mercury lamp (80W/e11), and the amount of ultraviolet rays required for complete curing (mJ/d) The tensile modulus, elongation, and flexibility of the cured film were measured.

The results were as shown in the table below.

The tensile modulus and elongation are measured according to JISK7113.
This was done in accordance with the. In addition, for flexibility, when the cured film peeled from the glass plate was bent 180 degrees, those that did not break were rated as O, those that were slightly damaged were rated △, and those that were significantly damaged were rated ×.

Test Example 2 Polyoxytetramethylene glycol (MW 2.0
00), tolylene diisocyanate, and 2-hydroxyethyl acrylate, 50 parts of urethane acrylate oligomer, 45 parts of acrylate of caprolactone adduct of tetrahydrofurfuryl alcohol, 5 parts of vinylpyrrolidone, 3 parts of benzophenone, and 1 part of diethylaminoethanol. The diameter after coating is 2
After coating to a thickness of 50 μm and curing at a linear speed of 100 m/min using a 160 W/aa high-pressure mercury lamp, Examples 1 to 5 and Comparative Examples 1 to 3 were further applied for the outer layer.
The diameter after coating each optical fiber coating material is 4
00 μm, and cured at the same speed using the same high-pressure mercury lamp as above.

The optical fiber coated body thus obtained was prepared in Example 1.
The bobbin winding properties using the optical fiber coating materials No. 5 to 5 were very good, and no increase in transmission loss was observed, but Comparative Examples 1 to 3 were significantly inferior to the above characteristics, and the ldb/db/ An increase in transmission loss greater than Iua was observed.

Note that the bobbin winding characteristics are obtained by examining the increase in transmission loss when bobbin winding (tension 80 g) is performed on a drum having a diameter of 30 cm.

From the above test results, it has been found that the coating material for optical fibers according to the present invention can provide a cured film with an extremely fast curing speed and excellent toughness that contributes to improving the reliability of optical fibers. it is obvious.

Claims (1)

[Claims] (1) a) Urethane (meth)acrylate oligomer,
b) a compound that is liquid at room temperature and has a low viscosity and contains one or more polymerizable carbon-carbon double bonds in one molecule, which has at least the effect of acting as a reactive diluent for component a; and c) a photopolymerization initiator. Coating materials for optical glass fibers, including
A coating material for an optical glass fiber, characterized in that, in addition to the above components a, b, and c, d) an ester of a hydantoin diol and (meth)acrylic acid is contained.