KR19990061688A - UV curable resin composition for optical fiber outer coating - Google Patents

Abstract

The present invention relates to an ultraviolet curable resin composition for external coating of an optical fiber, and more particularly, two or more monofunctional monomers and acrylate functional groups having a urethane acrylate oligomer as a main component, and containing one acrylate functional group as a reactive monomer component. The UV curable resin composition is useful for external coating to protect the glass surface of the optical fiber because the polyfunctional monomer and the silane monomer contained in a specific content range and the photopolymerization initiator are added to provide excellent tear strength and adhesion. It is about.

Description

UV curable resin composition for optical fiber outer coating

The present invention relates to an ultraviolet curable resin composition for external coating of an optical fiber, and more particularly, two or more monofunctional monomers and acrylate functional groups having a urethane acrylate oligomer as a main component, and containing one acrylate functional group as a reactive monomer component. The UV curable resin composition is useful for external coating to protect the glass surface of the optical fiber because the polyfunctional monomer and the silane monomer contained in a specific content range and the photopolymerization initiator are added to provide excellent tear strength and adhesion. It is about.

With the development of the electronics, information, and telecommunications industries, interest in optical fibers, which is emerging as an important basic material for these industries, is increasing day by day. Since the optical fiber is made of quartz-based glass, it is very weak to external impact. Thus, the optical fiber is coated with a coating agent to minimize deformation or loss of the optical signal during optical signal transmission. However, the coating agent coated on the optical fiber causes defects between the optical fiber and the coating layer due to microbending of the optical fiber as the external temperature is changed, thereby causing a transmission loss. In particular, this phenomenon occurs more severely at low temperatures. In order to solve this problem, the coating layer should have a very low modulus, but another problem that the tear strength of the surface is weakened by imposing a low modulus.

In order to increase the tear strength of the exposed coating layer to prevent the surface damage from the outside by introducing a double coating layer to the outer coating on top of the inner coating layer again.

Therefore, conventionally, the optical fiber is the outer coating of the surface again with a coating agent having another property on the inner coating layer. In general, the internal coating should have proper adhesion to the optical fiber (quartz glass), maintain soft and tough physical properties to overcome the microbanding phenomenon caused by external shocks or temperature changes. Therefore, no light loss or property degradation should be caused.

On the other hand, the outer coating agent is excellent in the adhesive strength with the inner coating layer should not be peeled off between the coating layer, for this purpose, an ultraviolet curable resin composition having excellent adhesive strength is required. Conventional techniques for outer coatings for external protection of optical fibers have been carried out by outer coating by extrusion or outer coating of UV curable coatings.

In the outer coating by extrusion, a silicone resin is used as the inner coating layer, and the outer coating layer has a method of applying a silicon-polyimide resin solution by a melt extrusion process (Korean Patent Publication No. 89-9816). However, there is a drawback that the curing rate of the silicone resin introduced into the inner coating layer is very slow and the volatile solvent in the outer coating liquid deteriorates due to polymerization at high temperatures. As another method, the inner coating layer is composed of a soft polymer having a low glass transition temperature, and the outer coating layer is a method of applying a liquid polyvinyl chloride plastisol containing a chemical blowing agent [Korean Patent Publication No. 90-15733]. However, this also has the drawback that deterioration occurs as pointed out above. The coating according to the conventional method described above has a disadvantage in that the manufacturing speed of the optical fiber cannot be increased because the curing speed of the resin is small.

For this reason, in recent years, ultraviolet curing resins having a relatively high curing rate have been widely used as coating materials for optical fibers. As a method using an ultraviolet curable coating agent, there is a method of coating an optical fiber with a single ultraviolet curable resin (Korean Patent Publication No. 85-4447), but it does not satisfy the above-mentioned problems. As another method, there is a method of using an ultraviolet curable coating agent as the outer coating layer (US Pat. No. 4,472,019). However, the adhesive strength with the inner coating layer is poor by emphasizing only the toughness.

In the present invention, a polyether polyol, a hydroxyl group-containing acrylic derivative, and a urethane acrylate oligomer polymerized with diisocyanate are blended as a main component to maintain tear strength and elongation at break, and include at least two monofunctional monomers and one or more acrylate functional groups. In addition to maintaining the tear strength required as an external coating agent by using a polyfunctional monomer in combination, and a small amount of vinyl trimethoxysilane monomer is added to maintain the adhesion to the inner coating layer regardless of humidity, and also photopolymerization The present invention was completed by increasing the curing rate by adding an initiator to increase the manufacturing speed of the optical fiber.

Accordingly, an object of the present invention is to provide an ultraviolet curable resin composition having excellent hydrolysis resistance, antihygroscopicity and antiabsorbability, and excellent adhesion to an inner coating layer, which is useful as an outer coating layer of an optical fiber.

30 to 80% by weight of the urethane acrylate oligomer having a number average molecular weight of 500 to 40,000; 20 to 50% by weight of a monofunctional monomer containing one acrylate functional group; 5 to 30% by weight of a multifunctional monomer containing two or more acrylate functional groups; 0.1 to 10% by weight of silane monomers; And ultraviolet curable polyurethane resin compositions for external coating of optical fibers containing 0.1 to 10% by weight of a photopolymerization initiator.

Referring to the present invention in more detail as follows.

The present invention has excellent hydrolysis resistance, anti-hygroscopicity and anti-absorption property, and also excellent adhesion to the inner coating layer. In particular, since the viscosity of the resin composition is low, the coating property of the optical fiber on the inner coating layer is good and the curing speed is high, so that the coated optical fiber is fast. It is possible to increase the production speed of the present invention relates to an ultraviolet curable resin composition for coating the optical fiber outer surface.

The urethane acrylate oligomer used in the present invention has a number average molecular weight distribution in the range of 500 to 40,000, preferably in the range of 500 to 30,000, and has a carbon-carbon double bond at the sock end.

The urethane acrylate oligomer is a polymer prepared by polymerizing a polyether polyol, a hydroxyl group-containing acrylic derivative and a diisocyanate compound, wherein the polyether polyol has a number average molecular weight of 300 to 30,000, preferably 500 to 10,000, The diisocyanate compound is used in general urethane synthesis, and both aliphatic or aromatic diisocyanates are applied.

Moreover, a urethane acrylate oligomer is contained in 30 to 80 weight% in the resin composition of this invention.

The resin composition according to the present invention contains a reactive monomer and a silane monomer in addition to the polyurethane oligomer described above.

The reactive monomer used in the present invention has a carbon-carbon double bond, which enables radical polymerization, and crosslinking with an internal coating agent. In general, the use of a crosslinking agent increases the tensile strength, but drops the tensile force rapidly and hardens at low temperatures and bends at high temperatures. However, the present invention contains a reactive monomer capable of hydrogen bonding to form a kind of physical crosslink to add a limited tear strength without excessively reducing the tension. As such a reactive monomer, a monofunctional monomer containing one acrylate functional group and a polyfunctional monomer containing two or more acrylate functional groups as well as a silane monomer are used in combination. When the hardened | cured material with comparatively low elastic modulus is calculated | required, it is preferable to use a single functional compound, but the elastic modulus of hardened | cured material can also be adjusted by using a polyfunctional compound together at an appropriate ratio.

Monofunctional monomers applicable in the present invention include 2-ethylhexyl acrylate, lauryl acrylate, isobornyl acrylate, caprolactone acrylate, vinyl pyrrolidone, diacetone acrylamide, isobutoxymethyl acrylamide, acryl Amide, N , N -dimethyl acrylamide, acrylic acid, itaconic acid, dimethyl aminoethyl acrylate, and the like. The monofunctional monomer as described above is included in the range of 20 to 50% by weight, preferably 25 to 45% by weight in the total resin composition according to the present invention. If the content of the monofunctional monomer contained in the resin composition of the present invention is less than 20% by weight, the viscosity is increased, the production rate is lowered, and if it is more than 50% by weight, there is a problem that the curability and tear strength is lowered.

In addition, as the multifunctional monomer that can be applied in the present invention, 1,6-hexanediol diacrylate, ethoxylated bisphenol A diacrylate, tripropylene glycol diacrylate, butanediol diacrylate, polyethylene glycol diacrylate , Triethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and the like. Said polyfunctional monomer is contained in the range of 5-30 weight% in the total resin composition which concerns on this invention, Preferably it is 10-25 weight%. When the content of the multifunctional monomer contained in the resin composition of the present invention is less than 5% by weight, the tear strength is lowered. When the content of the multifunctional monomer is more than 30% by weight, the coating film may be easily broken.

In addition, in the present invention, a resin composition for external coating of the optical fiber using urethane acrylate as a basic oligomer, and contains a silane monomer in order to prevent the adhesion to the inner coating layer due to the external environment change is reduced. However, as the humidity increases, moisture is present between the coating layers, thereby weakening the adhesion between the inner coating agent and the outer coating agent. However, the silane monomers used according to the present invention not only increase the adhesion of the coating agent to the substrate but also fundamentally reduce the moisture absorption rate of the coating material, thereby fundamentally blocking the influence of humidity. Therefore, the silane monomer not only increases the adhesion between the inner coating agent and the outer coating agent but also fundamentally lowers the moisture absorption rate of the resin composition. The character of the silane monomers should have a carbon-carbon double bond that can bond with the oligomers used. Such silane monomers include vinyl trimethoxy silane, vinyl tri (methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxy silane, gamma-glycidoxy oxypropylmethoxy silane, and the like. Is to use vinyl trimethoxy silane. As such an adhesion increasing agent, the silane monomer is included in the range of 0.1 to 10% by weight in the total composition.

In addition, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) is contained in the total composition in the range of 0.1 to 10% by weight as a photopolymerization initiator. This gives affinity for the optical fiber internal coating.

In addition, a sensitizer (photopolymerization promoter), such as an amine compound, may be used together as needed.

When the present invention is described in more detail as follows, the present invention is not limited thereto.

Examples 1 to 3 and Comparative Example 1

Next, the composition as shown in Table 1 was prepared to prepare a composition for external coating of optical fiber.

In addition, in the following Table 1, the urethane acrylate oligomer has a number average molecular weight of 4,000. The photoinitiator used Irgacure 184 manufactured by Sivagai Company, Switzerland.

division Example (% by weight) Comparative Example 1 (% by weight) One 2 3 Urethane acrylate oligomer 60 60 60 60 2-hydroxyethyl acrylate 5 5 5 5 Isobonyl Acrylate 15.5 14 12 16 1,6-hexanediol diacrylate 5 5 5 5 Ethoxylated Bisphenol A Diacrylate 5 5 5 5 Tripropylene glycol diacrylate 5 5 5 5 Vinyltrimethoxysilane 0.5 2 4 - Irgacure 184 4 4 4 4

Experimental Example :

The acrylic compositions blended in Examples 1-3 and Comparative Example 1 were cured to a thickness of 65 μm on the cured product of the optical fiber internal coating agent (DSM Desotech Inc., Desolite 950-106). The adhesion and mechanical properties of the cured coating film are measured and shown in Table 2 below.

Adhesion to Glass Measurement

The adhesion of the cured resin was measured after leaving the coating on the inner coating material for one week at 50% humidity or after 24 hours at 95% humidity. The surface of the specimen was prevented from evaporation of moisture with a polyethylene powder-water slurry prior to removal from the water softener. At this time, the thickness of the inner and outer coating layers were respectively 7.5 ㎛, the width of the specimen was 2.54 cm. The inner and outer layers of the specimen were bitten by an intro tester and pulled at an angle of 180 ° to measure adhesion.

division Example Comparative Example 1 One 2 3 Adhesive force to internal coating agent (N × 10 ^-2 ) Relative Humidity (50%) 63 75 84 57 Relative Humidity (95%) 60 73 83 53 Modulus (MPa) 920 912 915 932 Breaking strength (MPa) 28.8 27.8 27.1 28.6 Elongation at Break (%) 27.5 26.6 26.3 27.2

As described above, the resin composition according to the present invention contains a urethane acrylate oligomer having excellent tear strength and elongation at break as a main component, and contains a reactive monomer and a silane monomer containing a carbon-carbon double bond to the glass fiber. It is useful as an external coating for optical fibers because it enhances adhesion, has excellent moisture-proofing effect, and induces rapid curing.

Claims (5)

30 to 80% by weight of a urethane acrylate oligomer having a number average molecular weight of 500 to 40,000; 20 to 50% by weight of a monofunctional monomer containing one acrylate functional group; 5 to 30% by weight of a multifunctional monomer containing two or more acrylate functional groups; 0.1 to 10% by weight of silane monomers; And 0.1 to 10% by weight of a photopolymerization initiator. The ultraviolet curable resin for external coating of optical fiber according to claim 1, wherein the urethane acrylate oligomer is a polymer prepared by polymerizing a polyether polyol having a number average molecular weight of 300 to 30,000, a hydroxyl group-containing acrylic derivative, and a diisocyanate compound. Composition. According to claim 1, wherein the monofunctional monomer containing one acrylate functional group is 2-ethylhexyl acrylate, lauryl acrylate, isobornyl acrylate, caprolactone acrylate, vinyl pyrrolidone, diacetone acrylamide UV curable type for external coating of optical fiber, characterized in that one or two or more selected from isobutoxymethyl acrylamide, acrylamide, N , N -dimethyl acrylamide, acrylic acid, itaconic acid, and dimethyl aminoethyl acrylate. Resin composition. According to claim 1, wherein the multifunctional monomer containing two or more acrylate functional groups is 1,6-hexanediol diacrylate, ethoxylated bisphenol A diacrylate, tripropylene glycol diacrylate, butanediol diacryl It is one or a mixture of two or more selected from the group consisting of latex, polyethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc. UV-curable resin composition for optical fiber outer coating. The method of claim 1, wherein the silane monomer is selected from vinyl trimethoxy silane, vinyl tri (methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxy silane, and gamma-glycidoxy oxypropylmethoxy silane. UV curable resin composition for external coating of the optical fiber, characterized in that the species or a mixture of two or more kinds.