JPS60247609A - Reinforcing coated optical fiber - Google Patents

Abstract

PURPOSE:To maintain the transmission characteristics and high flexibility of an optical fiber and to increase the tensile strength in spite of the thin structure by forming a reinforcing coated layer of thermoplastic resin contg. many whiskers on the outide of a buffer layer coating the optical fiber. CONSTITUTION:The reinforcing coated layer 5 is formed on the outside of a buffer layer 2 coating an optical fiber 1 to obtain a reinforcing coated optical fiber. The layer 5 is made of thermoplastic resin 7 contg. many whiskers 6 oriented in the longitudinal direction of the fiber 1. Whiskers are fine fibers of a single crystals and whiskers of an inorg. substance whose coefft. of linear expansion is close to that of glass forming the optical fiber, e.g., potassium titanate or silicon nitride whiskers are preferably used as the whiskers 6. The amount of the whiskers 6 in the layer 5 is preferably regulated to 2-60wt% so as to reduce well the coefft. of linear expansion. Thermoplastic resin 7 is kneaded with whiskers 6, pelletized, and coated on the outside periphery of the buffer layer 2.

Description

[Detailed description of the invention] Technical field The present invention relates to reinforced coated optical fibers.

Conventional optical fibers, for example, are often used under harsh conditions when used as optical communication transmission lines, and require poor mechanical properties, as well as low transmission loss. For this reason, conventionally, for example, as shown in FIG. A reinforcing coating layer 3 (
A reinforced coated optical fiber was constructed by forming a secondary coat elk>k. However, the mechanical properties of reinforced coated optical fibers with this type of structure are not as good as that of L, and the linear expansion coefficients of glass and resin differ by one to two orders of magnitude, so temperature changes can cause major damage to the optical fiber. The stress may cause microbending in the glass that makes up the optical fiber, increasing transmission loss.

For this reason, recently, a large number of low pink glass fibers have been added to the outer peripheral surface of the buffer layer 2, as shown in Figure 2.
The reinforced coating layer 4 is formed by attaching the fibers 41 vertically and heating the thermosetting resin 42i impregnated in the fibers 41 with a heating means. In the thus obtained fL9 reinforced coated optical fiber, since the linear expansion coefficient of 1 m41 of glass fiber is small, the linear expansion coefficient of the reinforced coat layer 4 increases as the glass fiber content increases. The coefficient of linear expansion approximates that of the fiber 1, and therefore the difference in expansion and contraction between them becomes small, so there is no possibility that a large stress will be caused to the optical fiber 1 due to temperature changes.

However, in the reinforced coated optical fiber shown in Figure 2, it is necessary to use a considerable amount of glass fiber in order to sufficiently reduce the linear tensile coefficient of this reinforced coat layer. In addition, if a large amount of glass fiber is used, it becomes brittle and peels at the interface between the resin and glass fiber, causing cracks in the resin. There was a drawback that there were many O7n to be used.6 Moreover, to add to this drawback, there was also the problem that it was difficult to perform raw M' with a high working capacity. The reason for this is that reinforced coated optical fibers are produced by passing optical fibers and resin-impregnated glass fibers through a heating device such as an electric heater and completely curing the resin. This is because heat conduction is rapid and glass fibers also have a large heat capacity, making it difficult to thermoset the resin in a short period of time. Furthermore, the manufacturing equipment is complicated and expensive because it requires equipment such as a 1L thermosetting heating device for supplying long glass fibers or a liquid tank for thermosetting resin. Friend 6 Purpose of the Invention The non-explosion gA was created under these unforeseen circumstances, and it is an excellent machine that maintains the transmission characteristics, has a thin structure, is highly flexible, and has a high strength of warning. It is an object of the present invention to provide a reinforced coated optical fiber which has excellent characteristics and can be produced with high efficiency. It is characterized in that a reinforcing coating layer containing a large number of whiskers and made of a specific thermoplastic resin is formed on the outer circumferential surface of the front layer a using chewy fibers.

dark example The present invention will be explained in detail below with reference to the drawings.

As shown in FIG. 3, a reinforced coated optical fiber according to an embodiment of the present invention includes an optical fiber 1 coated with a layer 7t, a reinforced coat layer 5 provided on the outer circumferential surface of a buffer layer 2, and a reinforced coat layer 5 provided on the outer peripheral surface of a buffer layer 2. layer 5
is composed of a thermoplastic resin 7 containing nine whiskers 6, each oriented in the longitudinal direction of the optical fiber 1.

The whiskers herein are single-crystal fibers made of potassium titanate, silicon ash, silicon nitride, polyoxymethylene, and the like. When using whiskers, it is possible to use only one type of whisker, such as potassium titanate whiskers, or to use a combination of two or more whiskers, such as a combination of potassium titanate whiskers and silicon carbide whiskers. However, it is preferable to use a whisker made of an inorganic material such as potassium titanate or silicon nitride, which has a coefficient of linear expansion close to that of the glass constituting the optical fiber. An example of a whisker is potassium hexatitanate (K, 0.6TLOJ), which is a fine white needle crystal with an average fiber length of 10 to 208 m and a fiber diameter of 0.2 to 0.5 μm. It also has extremely good compatibility with the reinforced housing layer 5.
The content ratio of whiskers 6 in is preferably 2 to 60% by weight in order to achieve a sufficient reduction in the coefficient of linear expansion.
More preferably 10 to 40% by weight. And enhanced W161
Regarding the formation of layer 5, whiskers 6<em>v are added to thermo-OT plastic resin 7 in advance to form a pellet. It is preferable to coat the outer circumferential surface of the buffer layer 2 with the whisker from the viewpoint of uniform scattering of whiskers and environmental hygiene issues. Furthermore, although the present invention is not limited to orienting the whiskers 6 in the longitudinal direction of the optical fiber 1, by orienting the whiskers in the longitudinal direction, the tensile coefficient of the reinforcing coating layer can be further reduced. This is good because it leads to When the whiskers 6 are oriented in the longitudinal direction of the optical fiber 1 and in good condition, the whisker-containing resin can be easily removed by extruding the resin containing the whiskers using an extruder at a rate of about 10 times and then extruding it for coating. As thermoplastic resin 7 &'@, polyester resin,
It is made of polyamide resin, polyacetal resin, etc., and one is appropriately selected based on the required properties in addition to the coefficient of linear expansion.

Next, a specific example of the present invention will be described in comparison with one that does not include whiskers.

Specific example 1> An optical fiber is coated with # front layer to have an outer diameter of 0.4 mm,
# Thermoplastic nylon 12 containing 5% by weight of potassium hexatitanate whiskers is laminated along the outer circumference of the front layer, and this is extruded and stretched at 20 times to form a reinforced coating layer. A reinforced coated optical fiber with a diameter of 0.911 m) was obtained. This doesn't mean "optical fiber 1".

Specific Example 2> Containing whiskers of potassium hexatitanate 10% by weight and L 7r eb, & 1 on the knee body side 11 in exactly the same way.
A reinforced coated optical fiber of similar size was obtained. This is ``
Optical Fiber 2 Comparative Example> A reinforced coated optical fiber with the same dimensions as in Specific Example 1, in which the whiskers were not contained in nylon 12, was obtained. This meeting will be referred to as ``Comparative Optical Fiber''.

The results of examining the optical fibers 1 to 3 described above with respect to open bale strength, molding shrinkage, linear expansion coefficient, and molding state are shown in the following table.

Table As can be seen from this table, resins containing whiskers have higher tensile strength, smaller mold shrinkage, and lower coefficient of linear expansion than resins containing no whiskers. Further, there was no roughness on the resin surface, and no interfacial peeling that would cause cracks between the resin and whiskers was observed.

Here, the reinforced coated optical fiber assembly of the present invention is compared to a conventional reinforced coated optical fiber in which long glass fibers are all longitudinally attached, and a nine-piece optical fiber used in place of glass minute ms'e whiskers. To explain by comparison, in the case where long glass fibers are used in full lengthwise manner, if the content ratio of the long glass fibers in the reinforcing coating layer is not 60 to 80%, the coefficient of linear expansion is low. However, in the present invention, the linear expansion coefficient of the reinforcing coating layer can be increased without vertically attaching the glass 41 and the female. Since it reduces the thickness of the vehicle, it has more flexibility than conventional products, and it is also possible to reduce the thickness of the reinforcing coating layer throughout the vehicle.

In addition, when glass microfibers a are used, surface roughness of the reinforcing coating layer becomes a problem, which becomes a serious problem especially when thinning the wall, but whiskers have a size of 1150 to Because it is small at 1/100, there is no need for surface roughening during molding. Also, when comparing the tensile strengths, it depends on whether the reinforcing coating layer using whiskers can achieve a tensile strength of 51 degrees.

In addition, in the present invention, two optical fibers 1 each having a buffer layer 2 formed on the outer circumferential surface thereof are lined up as shown in FIG. Alternatively, as shown in FIG. 5, a buffer layer 2 may be formed on the outer peripheral surface of the two optical fibers 1 so that they are integrated. The reinforcing coating layer 5 may also be formed on the outer peripheral surface of the buffer layer 2.

Effects of the Invention As described above, according to the present invention, by using whiskers, which are single-crystal microfibers, in the reinforcing coating layer, the coefficient of linear expansion of the reinforcing coating layer becomes small, which reduces the strength of the optical fiber due to temperature changes. By suppressing stress, it is possible to prevent an increase in transmission loss. Furthermore, it is possible to obtain a reinforced coated optical fiber having a high tensile strength, high flexibility, and good mechanical properties while having a thin reinforced coat layer. Furthermore, the whisker-containing resin is a thermoplastic resin, and since conventionally thermosetting resins were used, the curing time was a problem, and the line speed could be significantly increased. , can be produced at high capacity. Since the reinforced coated optical fiber of the present invention can be manufactured by a general extrusion method, it requires a heating device for thermosetting the resin, a long glass fiber supply device, and a thermosetting method. Production can be carried out using a simple device that does not require a resin liquid tank or the like.

[Brief explanation of the drawing]

1 and 2 are front views showing a conventional reinforced coated optical fiber, FIG. 3 is a front view showing a reinforced coated optical fiber according to an embodiment of the present invention, and FIG. 4. FIG. 5 is a front view showing reinforced coated optical fibers according to other embodiments of the present invention, 1... Optical fiber, 2... Acid #l-55... Reinforced coating layer, 6 ...whisker, 7...thermoplastic resin.

Claims (1)

[Scope of Claims] 11) An optical fiber crushed by a buffer layer, a reinforcing coating formed on the outer peripheral surface of the buffer layer, and C, the reinforcing coating layer containing a large number of whiskers. Is it made of plastic resin? Features: Reinforced coated optical fiber. (2) The whisker content in the reinforcing coating layer should be 2 to 60%. A reinforced coated optical fiber according to claim 1.