JPH01276105A - optical fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] Regarding the present invention/i-element fiber, resin coating 81. is particularly suitable for high-speed drawing. It concerns a new structure of the original fiber.

[Conventional technology]

Since the original glass fiber has a small diameter and low mechanical strength as it is drawn from the glass base material, it is generally coated with RK during the drawing process to obtain the original fiber. FIG. 1 shows a cross-sectional structure of an example of the original fiber strand (hereinafter referred to as Hikari 7-IPA) 1, which is the subject of the present invention. An inner resin coating 5 is provided as a buffer coating layer, and an outer resin coating 4 is provided as a protective coating layer. The inner resin coating 3 of the buffer coating layer serves as a primary coat and also has a cushioning effect, and is made of a relatively soft resin with an elastic modulus of 1 kP/lI or less, and the outer resin coating 4 of the protective coating layer acts as a shell. It imparts high mechanical strength to the glass base fiber and has the effect of suppressing an increase in optical transmission loss, and uses a relatively hard resin with an elastic modulus of 10 k)/Ryu 2 or more.

As these coating resins, photocurable resins having a fast curing speed are often used from the viewpoint of productivity. A photocurable resin is cured by a photoinitiator contained in the resin that absorbs light sound having a wavelength in the ultraviolet region, cleaves it, and causes a radical reaction. Therefore, the effective curing wavelength range of the photocurable resin is mainly determined by the effective excitation wavelength range of the photoinitiator, and it matches the light absorption characteristics of the photoinitiator, so it is cured by irradiation with photo-sound in this wavelength range. .

Regarding the manufacturability of the original fiber 1 with the above structure, is it possible to coat the drawn glass original fiber with a coating resin? The so-called tandem manufacturing method, in which the coating and curing steps are performed sequentially for each layer,
A two-layer simultaneous coating method is known in which two layers of coating resin are simultaneously applied and cured.

FIG. 2 shows an outline of a two-layer alpha-fiber manufacturing apparatus that applies a coating resin together with the sheath layer in tandem. Base material sending device 517il: sends all of the base material 8 to the wire drawing furnace 6.

The base material feeding device 5 and the drawing furnace 6 constitute a drawing equipment f7. The drawn glass fiber 2 is coated with a photocurable resin forming an inner layer coating by a coating device 15, and cured by an ultraviolet irradiation device 15. After the inner layer is coated with the resin, a photocurable resin forming the outer layer is coated on the outer periphery of the inner layer by the coating device 16, and cured by the ultraviolet irradiation device 14 to form the original fiber 1 with the two-layer coating. While the winding device 12 is being picked up by the take-up capstan 11
It is then wound up.

3rd □□□ is a schematic diagram of a two-layer coated optical fiber manufacturing apparatus using a two-layer simultaneous coating method in which resins for the inner layer coating and the outer 1rI coating forming the two-layer resin coating are simultaneously applied and cured. W. The same symbols as in Figure 2 indicate the same parts. The difference from the tandem method shown in FIG. 2 is that a two-layer coating device 9 simultaneously forms a two-layer coating on the glass fiber 2 with a base material 8 drawn in a drawing furnace 6, an inner layer resin and an outer layer resin. The coated inner and outer layer resins are completely cured using an ultraviolet irradiation device i110iC to form a two-layer coated original fiber 1.

[Problem to be solved by the invention]

Regarding the photocurable resin used as the coating material applied to the original fiber, the relatively soft one used for the inner layer coating generally has a slower curing speed than the relatively hard one used for the outer layer coating.

Therefore, in the tandem system shown in FIG. 2, the inner layer curing lamp of the ultraviolet ray irradiation device 13 for curing the resin of the inner layer coating is used, and in the simultaneous two-layer coating shown in FIG. Measures have been taken to make the double-layer simultaneous curing lamp extremely powerful, or to arrange a large number of curing lamps in series or parallel. . but,
In both the tandem method and the two-layer simultaneous coating method, the relatively soft i-curing resin that forms the entire inner buffer coating layer has a slow curing speed, which is an obstacle to increasing the drawing speed. There is a problem with becoming.

The present invention addresses the difference in the light curing speed between the inner and outer layers in a fiber with such a two-layer coating structure, and in particular improves the curing speed of the relatively soft inner layer coating resin, thereby creating an original fiber with a coating structure suitable for high-speed drawing. The entire purpose is to provide.

[Failure to solve the problem]

The present invention uses a two-layer photocurable resin coating layer on the outer periphery of the glass fiber! This original fiber is characterized in that the effective curing wavelength range of the photocurable resin forming each layer is different. A particularly preferred embodiment of the present invention is that the photocurable resins formed on each layer have different initiators added, and the above-mentioned source fibers have different effective wavelength ranges for curing.

The present invention is based on the effective curing wavelength range of the outer layer 40-element curable resin and the inner rt! This resin is different from that of resin I3.

[Effect]

In general, the thickness of the coating applied to the fiber is approximately 10 to 100 μm for the -layer, but at this thickness, the attenuation due to the original absorption cannot be ignored. Of course, when the inner layer resin is cured by passing through one outer layer resin as shown in the two-layer simultaneous coating method, but also in the case of the tandem layer-by-layer coating method shown in Fig. It is also important that the inner layer resin is cured by a source that passes through the outer layer resin when the resin is cured.

In the present invention, by using resins having different effective curing wavelength ranges as the outer layer resin and the inner layer resin, the light in the effective wavelength range for curing the outer layer resin is absorbed by the outer resin layer, and the intensity in this wavelength range is attenuated. However, the light in the wavelength range that is effective for curing the inner layer resin is transmitted light that is not absorbed, and is an original fiber that can also cure the inner layer resin. To explain this At in more detail in Figure 6, Figure 6 shows the original wavelength as the horizontal axis and the total light intensity or absorbance as the vertical axis. b is a diagram showing the relationship between the outer layer transmitted light intensity (inner layer irradiation intensity wavelength characteristic 01 and inner layer absorption wavelength characteristic d). In the present invention, the outer layer absorption wavelength characteristic and the inner layer absorption wavelength characteristic d, that is, the curing effectiveness of the outer layer and inner layer Therefore, when irradiated with a lamp with a light intensity wavelength characteristic a that can cover the effective curing wavelength range of both the inner layer and the outer layer, the light is first absorbed by the outer layer and attenuated in accordance with the outer layer absorption wavelength characteristic. ?The wavelength characteristics of the irradiated transmitted light are as shown in C, but since it is not attenuated in the inner layer curing effective wavelength range shown in d, the inner layer resin can effectively absorb all of this transmitted light and achieve rapid curing.

In the present invention, the curing effective wavelength characteristics of the inner and outer layer resins! 4
Any method can be used to achieve this, but
As mentioned above, the effective curing wavelength range of the photocurable resin is mainly determined by the effective excitation wavelength range of the photoinitiator, and it matches the light absorption characteristics of the photoinitiator. This can be achieved easily by selecting. In our experiments, the amount of photoinitiator added was 0.5 to 10% by weight.
It was common.

As the photocurable resin in the present invention, various resins such as polyurethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, melamine acrylate, and silicon acrylate can be used.

Table 1 shows the effective excitation wavelengths of main photoinitiators.

Table 1 Also, in Figure 5 (a) and (b), typical initiator particles (Bl, (C1) whose chemical names and chemical structural formulas are shown below
shows the optical absorption wavelength characteristics of

2-Methyl-(41methylthio)phenyl2-
Morpholino-1-pronocnonone H3 (Bl 1-hydroxycyclohexylphenyl ketone (Cl 2,2-dimethoxy-2-phenylacetophenone-CH3 It is preferable to use an irradiation rung with output characteristics capable of irradiating the entire area. Figures 4+a+ to (C) show the output wavelength characteristics of typical resin curing lamps.

〔Example〕

Example 1 All the double-layer coated optical fibers shown in FIG. 3 were fabricated by simultaneous coating of two layers. The prototype double-layer coated optical fiber has an outer diameter of 12
1 inner layer thickness 200μ on the outer periphery of 5μmφ glass fiber
Two layers of photocurable resin with an outer layer thickness of 250 μm were heated at a linear speed of 20
With a structure coated at 0 m/min, the degree of curing of the photocurable resin in the inner layer was evaluated using the gel fraction using a solvent extraction method. As the coating resin, a relatively soft urethane acrylate resin is used for the inner layer and a relatively hard urethane acrylate resin for the outer layer, and the type and amount of the photoinitiator (A, B, C) added is varied. I made a comparison. Table 2! Five types of samples 1 to 5 prototyped in
The structure and evaluation results are shown. 42, 3, and 5 are products of the present invention, and A1 and 4 are comparative products. As the resin curing lamp, a lamp having the output wavelength characteristics shown in FIG. 4 was used.

Table 2! From this, we understand the following. 41 and Ya4 are optical fibers with a conventional structure in which the same amount of the same photoinitiator or C is added to both the inner layer resin and the outer layer resin, and the inner layer resin gel fraction is 69X and 72%, respectively. Curing of the resin was insufficient.

On the other hand, in the fibers 42, 43 and 5 of the present invention in which different photoinitiators were added to the inner layer resin and the outer layer resin, the gel fraction of the inner layer resin was 91%, 88X, and 75%, respectively, which correspond to the conventional products. The degree of hardness is increasing.

Therefore, the fibers 42, 43 and A5 of the present invention effectively utilize the irradiated light from the lamp that has passed through the outer layer resin,
Since the curing speed increases, it is advantageous for high-speed wire drawing.

Example 2 A two-layer coated Hikari 7 Eyeper was fabricated by applying the tandem coating layer by layer as shown in FIG. 2. The prototype double-layer coated optical fiber had a structure in which the outer periphery of a glass fiber with an outer diameter of 125 μmφ was coated with two layers of photocuring resin, each with an inner layer thickness of 200 μm and an outer layer thickness of 250 μm, at a total linear speed of 300 m/min. The degree of curing of the photocurable resin was evaluated in terms of gel fraction using a solvent extraction method. The coating resin is the inner layer and the outer layer! −
Both materials were made from silicone acrylate. Table 2 shows the configurations of two prototypes, A6 and J167. As in Example 1, a lamp having the output wavelength characteristics shown in FIG. 94 was used as the resin curing rung.

The following can be understood from the hills in Table 2.

A6 is an optical fiber with a conventional structure in which the same amount of the same photoinitiator is added to both the inner layer resin and the outer layer resin, and the inner layer resin gel fraction is 71%, and the degree of curing of the inner layer resin is still low and curing is insufficient. Met.

In contrast, the fiber of the present invention, A7, had a high gel fraction of 85% in the inner layer resin, and had an increased degree of curing. Therefore, A7 of the present invention is advantageous for high-speed drawing because the curing speed is increased by effectively utilizing the irradiation light from the lamp that completely passes through the outer layer resin.

〔Effect of the invention〕

As explained above, the double-layer coated optical fiber of the present invention has
Since the effective curing wavelength range of the photocurable resin that forms the coating of each layer is different, the inner layer resin can be effectively cured by the ultraviolet rays that pass through the outer layer, and the curing time is shortened, making it suitable for high-speed wire drawing. It is a suitable source fiber.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the original fiber according to the present invention, Figure 2 is a schematic diagram of a device for manufacturing a double-layer coated optical fiber that coats the entire sheath layer in tandem, and Figure 3 is a double-layer coated optical fiber coated with two layers simultaneously. A schematic diagram of fiber manufacturing equipment, Figure 4 (al to ICI are output wavelength characteristics diagrams of typical resin curing lamps of different types, Figures 5 (a) and (b) are typical diagrams used in the embodiments of the present invention. The light absorption wavelength characteristic diagram of the original initiator and (Bl l (C1), FIG. 6 is a diagram for explaining the present invention in detail. 1...Original fiber, 2...Glass fiber, 3...
- Inner layer resin coating, 4... Outer layer resin coating, 5... Base material feeding device, 6... Wire drawing furnace, 7... Wire drawing device, 8...
- Base material, 9... Two-layer simultaneous coating device, 10... Ultraviolet irradiation device, 11... Pick-up Sicapstan, 12...
Winding device, 15.14... Ultraviolet irradiation device, 15.1
6... Coating device.

Claims (2)

[Claims] (1) An optical fiber comprising two photocurable resin coating layers around the outer periphery of a glass fiber, wherein the photocurable resins forming each layer have different effective curing wavelength ranges. (2) The optical fiber according to claim 1, wherein the photocurable resin forming each layer has different effective curing wavelength ranges due to different initiators added.