JPS6291519A - Curable resin composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition which can give a cured product having a low modulus even at low temperatures and improved in water resistance and heat resistance, by mixing a specified urethane acrylate oligomer with isodecyl acrylate at a specified rate. CONSTITUTION:This resin composition contains 50-80wt% urethane acrylate oligomer having a polytetramethylene ether structure between respective urethane bonds and 50-20wt% isodecyl acrylate. Said urethane acrylate oligomer can be obtained by reacting, for example, a diisocyanate with polytetramethylene ether glycol and a hydroxyalkyl acrylate. Said resin composition is suitable as an optical fiber cladding material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a curable resin composition, and more particularly to a resin composition for coating optical transmission glass fibers (hereinafter abbreviated as optical fibers), and more particularly, the present invention relates to a curable resin composition for coating glass fibers for optical transmission (hereinafter abbreviated as optical fibers). The present invention relates to a resin composition for coating optical fibers which has low water resistance and excellent heat resistance.

When transmitting light through an optical fiber, when mechanical lateral pressure is applied to the optical fiber, the transmitted light is weakened by microbending, resulting in transmission loss. The primary coating in contact with the glass surface is therefore chosen to have a very low modulus of elasticity in order to minimize this microbending. Furthermore, desirable properties for this secondary coating include a low modulus of elasticity even in low-temperature environments, and excellent water resistance and heat resistance.

As a result of extensive studies on combinations of various urethane acrylates and monofunctional acrylates, the present inventors have completed the coating resin composition of the present invention.

That is, the present invention uses 50 to 80% by weight of a urethane acrylate oligomer having a polytetramethylene ether structure between each urethane bond and 5% by weight of isodecyl acrylate.
This is a curable resin composition characterized in that it contains 0 to 20% of heavy weight.

By combining these two components, the cured product has a sufficiently low modulus of elasticity even at low temperatures, and provides excellent physical properties such as water resistance and heat resistance.

The curable resin composition of the present invention may further include a photopolymerization initiator, monofunctional and polyfunctional acrylates other than isodecyl acrylate, a silane coupling agent, a peeling agent, an ultraviolet absorber, an antioxidant, Various additives such as fillers can be blended.

The urethane acrylate oligomer used in the present invention can be produced by a known method, for example, by reacting a diisocyanate with a polytetramethylene ether glycol and a hydroxyalkyl acrylate. Suitable diisocyanates include aliphatic or aromatic compounds such as isophorone diisocyanate, 2,4-)lylene diisocyanate or its isomers, and hexamethylene diisocyanate, and tolylene diisocyanate is particularly preferably used.

Also suitable hydroxyalkyl acrylates include, for example, 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate.

Diacrylate termination is possible here in various ways. That is, first, diisocyanate and polytetramethylene ether glycol were mixed with a number average molecular weight of 800 to 5,000.
0, preferably 2,000 to 20,000 to produce a polymeric diisocyanate,
It is then reacted with a 2 molar proportion of hydroxyalkyl acrylate to attach terminal unsaturated groups. Alternatively, a hydroxyalkyl acrylate and a diisocyanate are first reacted, and then the obtained unsaturated monoisocyanate and optionally a diisocyanate are co-existed so that the number average molecular weight is 800 to 50,000, preferably 2,000 to 20,000. React with polytetramethylene ether glycol.

This urethane acrylate oligomer is referred to in the present invention as 8
If it exceeds 0% by weight, it will become too viscous and difficult to use, and at the same time the elastic modulus of the cured product will increase;
If it is less than % by weight, the viscosity will be too low and coating will not be successful.

Isodecyl acrylate is an essential component of the present invention. As a result of various studies on monofunctional acrylates with relatively long side chains and fast curing speed, the present inventor found that isodecyl acrylate is superior, and compositions containing isodecyl acrylate have a low elastic modulus and a fast curing speed. Moreover, the resin liquid has fluidity even at low temperatures. The inventors also discovered that an optical fiber coated with this coating exhibits excellent transmission characteristics, leading to the present invention.

In the present invention, the photopolymerization initiator to be blended as necessary is not particularly limited, but examples include benzophenone,
Acetophenone, benzoin, benzoin isobutyl ether, benzoin isopropyl ether, benzoin ethyl ether, 4゜4'-bisdimethylaminobenzophenone, benzyl dimethyl ketal, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2.2
'-Diisopropylthioxanthone or 1-hydroxycyclohexylphenyl ketone is used.

Acrylates that can be used in the present invention are not particularly limited, but examples include tetrahydrofurfuryl acrylate, 2-hydroxy-3-phenyloxypropyl acrylate, butoxyethyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, Examples include hexyldiglycol acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, dicyclopentadiene acrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate.

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 500 c equipped with thermometer, stirrer and reflux condenser
cTolylene diisocyanate 34.8 in a four-loaf flask
g and 200 g of polytetramethylene ether glycol with a number average molecular weight of 12,000 and reacted at 70°C for 2 hours, and then 2-hydroxyethyl acrylate 24
．． 0 g was added, and the reaction was further carried out at 70° C. for 2 hours. After cooling, 258.8 g of oligomer was obtained. Next, 110 g of isodecyl acrylate and 15 g of benzyl dimethyl ketal were added and mixed to obtain the desired composition. After coating this composition on a glass plate to a thickness of 250 microns,
Curing was performed using a 20 W metal halide lamp at a conveyor speed of 20 m/min. Table 1 shows the results of measuring the physical properties of the cured film.

Example 2 21.0 g of tolylene diisocyanate was charged into a four-bottle flask similar to that used in Example 1, and 13.9 g of 2-hydroxyethyl acrylate was gradually added dropwise at 60°C. Allowed time to react. Next, 120 g of polytetramethylene ether glycol with a number average molecular weight of 2000 was added and reacted at 70°C for 3 hours. After cooling, 1
55 g of oligomer was obtained. Next, 103 g of isodecyl acrylate and 8 g of benzyl dimethyl ketal were added and mixed to obtain the desired composition. Table 1 shows the physical properties of the film cured in the same manner as in Example 1.

Example 3 42 g of tolylene diisocyanate was charged into a four-bottle flask similar to that used in Example 1, and 18.6 g of 2-hydroxyethyl acrylate was gradually added dropwise at 60°C.
The reaction was carried out at 0°C for 2 hours. After that, the number average molecule ff1l
OOO polytetramethylene ether glycol 16
0 g was added, reacted at 70°C for 3 hours, and after cooling, 220
．． 6 g of oligomer was obtained. Next, 200 g of isodecyl acrylate and 12 g of benzyl dimethyl ketal were added and mixed to obtain the desired composition. Table 1 shows the physical properties of the film cured in the same manner as in Example 1.

Table 1 Example 4 The compositions of Examples 1 to 40 were each applied to the surface of an optical fiber having a diameter of 125 μm spun at a speed of 50 m/min, and then cured by irradiation with ultraviolet light (lamp output: 2 kW, 2 lamps). The outer diameter of each optical fiber after coating was 300 μm, and no increase in transmission loss was observed due to coating, and the temperature at -40°C
No increase in transmission loss was observed up to this point.

Comparative Example A composition obtained by adding and mixing 60 g of urethane acrylate oligomer synthesized in the same manner as in Example 2, 40 g of lauryl acrylate, and 3 g of benzyl dimethyl ketal was cured in the same manner as in Example 1. The elastic modulus of the film was as follows at 20°C. 0
．． 17kg/mm2, 1.3kg/mm' at -30℃
It was 4.2 kg/in2 at -40°C.

As explained above, the cured resin composition of the present invention has a low elastic modulus even at low temperatures, has excellent water resistance and heat resistance, and has no increase in optical transmission loss, so it is suitable as an optical fiber coating material. There is.

Claims (1)

[Claims] 50-8 of urethane acrylate oligomer having polytetramethylene ether structure between each urethane bond
0% by weight of isodecyl acrylate and 50 to 20% by weight of isodecyl acrylate.