JPS63500685A - Intermediate workpiece with graded refractive index and its manufacturing method - 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] Chunichi++ construction with graded refractive index and U to L Kono's invention is a graded refractive index. pultrusion molding of an intermediate workpiece (preform) having a Alternatively, the present invention relates to a method for producing an intermediate material for extrusion molding.

When electromagnetic waves are transmitted through a material, the transmission speed depends on the material's refractive index. be done. When using electromagnetic waves with the same speed as visible light, for simplicity, the electromagnetic waves are It can be said that light travels through matter at the speed of light. Furthermore, it has a refractive index greater than that of air, for example. If we assume that light is incident on a substance that has would also be slower in this material, which follows Snell's law.

As a result of the above, light traveling along the axis of an optical fiber depends on the refractive index of the fiber. It can be said that the information is transmitted at a constant speed.

Light that travels outside the fiber rather than on its axis travels along the fiber's outer boundary, i.e., bent in the region between the fiber material and the cladding, or transmitted through the fiber.

This is because the light passing through the fiber loses some of its intensity between the source and the destination. It means to put away. This is called light attenuation. Furthermore, the refracted light is transmitted Due to the long distance, light along the axis of the fiber has a certain phase shift. That's what I reach.

In practice, the above phenomenon is explained by the so-called step index fiber (steppe index fiber). d 1ndex fiber), that is, the material has the next refractive index change point from the axis. (usually between the inner core of the fiber and the cladding) seen in fibers that have a

In other words, light is transmitted through such fibers in the form of impulses of light. The information is lost as this light impulse travels down the fiber.

However, optical fibers that are optically non-uniform (graded index distribution) – i.e., from a large index of refraction on the axis of the fiber to a small index of refraction at the outer circumference of the fiber. If you use a fiber whose refractive index changes continuously, The changing light is not refracted as it would be in a step-index fiber; It will be continuously bent towards the axis.

The information in the form of optical impulses transmitted through such fibers is time to reach their destination and therefore their signals are easily translated.

This feature in graded index fibers has only recently become known. Effectively used to transmit information through optical fibers made of glass or crystal became.

However, there are no descriptions of synthetic optical fibers based on this principle. Therefore, in the past literature there are no studies based on the step-index fiber principle. Only homogeneous fibers are noted.

U.S. Patent Nos. 4,138,194 and 4,161,500 disclose that the material is A method for producing a chemically uniform intermediate workpiece is disclosed. Methyl methacrylate As a base, small amounts of additives consisting of other acrylates and methacrylates are added A copolymer is used. The completed intermediate workpiece is then processed using optical fiber. Used to extrude bars.

Furthermore, in German Patent No. 1497545, the core of the fiber is It is based on styrene and the fiber cladding is polymethyl methacrylate. Disclosure of production of step index fibers based on lylate salts has been done. This manufacturing method uses a polystyrene core and polymethyl methacrylic acid. polymethyl methacrylic to make intermediate products with salt cladding. This consists of filling the core material into the tube of acid salt, then inside this The blank is heated until it becomes pliable, and then the optical fiber is extruded. .

Optical fibers made from intermediate products of the above type are optically uniform, so It is not well suited for transmitting information over long distances.

The refractive index decreases continuously from the fiber axis toward the fiber's circumference. Optical fiber indexes can be manufactured from composites with graded refractive index. That's what I found out. That is, according to the present invention, almost the same reaction parameters and solubility monomers having a different refractive index, and , by continuously changing the molar ratio of these monomers, graded A composite having a refractive index is created.

According to the invention, the Monomers are added to a tubular polymer material suitable for rotating walls, e.g. cladding. Be warned.

The monomers are then prepared in a generally known manner, e.g. peroxide-based A reaction initiator is used to apply radiation, either ultraviolet radiation or infrared radiation for heating. or alternatively by combining one or two of the above methods of polymerization. Polymerization is thereby carried out.

Polymerization takes place with the use of glass cladding and ultraviolet radiation stimulates the polymerization. When used for should have the same frequency as .

In order to better understand this invention, we will discuss aspects of equipment used in the production of intermediate products. Please refer to FIG.

The device shown in Figure 1 has an outer tube ( 1). Here, glass means glass of any nature. Ru. Plastics include both water-soluble and water-insoluble materials, as well as natural plastics. This includes both plastics and synthetic plastics.

This tube (1) is closed with an end piece (2', 2'') that has several functions . Firstly, the end piece (2', 2'') acts as a support member for the tube (1), and secondly, It functions as a fulcrum for the rotation of the tube (1).

The device for rotating the tube (1) is such that the end of the shaft is attached to the end piece (2', 2''). attached or when these end pieces are fastened to rotating bearings. These are of the conventional type, such as those that rotate the tube directly rather than the end piece. but, The device for rotating the tube is not an element of this invention and is therefore not shown in FIG. do not have.

The end pieces (2', 2'') can be fastened, for example by screws or by O-rings of inert material. The tube (1) is attached by any conventional method such as friction coupling between the end piece and the tube (1). (1) is concluded.

The end piece may be made of metal and/or plastic; It is effective if it is resistant to corrosion by monomers, and also has heat resistance, In other words, it is effective if it does not lose its shape when exposed to heat. braze, end piece (2″) is shown with bushing (3) and cannula (4); This cannula (4) is moved back and forth within the tube (1) through the end piece (2''). can be done. Such movement is controlled by a motor (5) and a cannula. This is indicated by the double-headed arrow above (4).

In order to prevent oxygen and microgas from entering the tube (1) between the end pieces (2', 2'') , for example, by supplying nitrogen as an inert gas into the tube (1) via the bush (3). may be provided.

Reactants (in this case monomers M, and/or Mt, or pure monomers) , or a mixture thereof) is introduced through the cannula. two monomers It is possible to embody a monomer compound consisting of - and more monomers. It is not necessary to use only one or two monomers; therefore, this The invention of ``How many monomers should be used, or what should be used, etc.'' The decisive factor for selecting monomers is not restrictive in terms of are the optical properties and other physical data for the finished product.

Cannula (4) contains monomers (M+, Mz), ultraviolet reaction initiator, and chain transfer. moving agent and, if appropriate, other additions suitable for the purpose. It is connected to a tube for supplying J(H).

The device described above exhibits two operations. First, a tube with an end piece (2', 2'') (1) performs a rotational movement.Secondly, the cannula (4) moves back and forth inside the tube (1). As a result, after a certain period of time, the inner surface of the tube is filled with material from the cannula (4). coated.

The intermediate workpiece manufacturing equipment rotates at high speed so that the material is evenly distributed. material When the injection begins, the rotation speed is very slow. 500~2000rpn+ Experience has shown that a rotation speed of approximately 100° rpm can be selected. Ru.

As mentioned above, the monomers MI and M2 are separately supplied to the cannula (4). carries out a third supply, for example a chain transfer agent and/or a UV initiator supply. It is also effective to

Additionally, peroxides and azo compounds to form free radicals are used to initiate the reaction. Other methods of initiating the reaction can be used, such as using milk.

The created intermediate workpiece must be as optically pure as possible, i.e. it does not distort the optical signal. During subsequent handling, the It becomes effective. Therefore, it is effective to start polymerization and continue it with ultraviolet radiation. be.

For example, when using a system where the reaction is initiated by peroxide, It should be noted that it is difficult to remove the heat of polymerization reaction. Therefore, purple It is preferred to use the simpler and cleaner method of polymerization by external radiation.

If ultraviolet radiation is applied, the tube (1) must be transparent to this type of radiation. In practice, this means selecting ultraviolet light with a frequency of 300-400 r+m. means you have to.

FIG. 1 shows a device (7) for emitting ultraviolet radiation. Pipe (1) is relatively It is also taken into consideration that since it rotates at high speed, the radiation hits the entire inner surface of the tube (1) evenly. must be

Having a molecular weight that is too large will cause the extrusion speed and polymer is undesirable because it affects the viscosity of the To do this, a chain transfer agent is added. Polyacrylate is 30.000~Zo With a molecular weight of o, 000, polystyrene has a molecular weight of 100,000 to soo, ooo. The amount is most appropriate.

The purpose of the above-mentioned device is to provide a medium with a refractive index that decreases from the axis of rotation to the outer periphery. The purpose is to manufacture partially processed products.

This is done by first supplying the monomer or monomers with the lowest refractive index. The refractive index is then determined by continuously changing the molecular weight of monomers M1, M2. It is increased by changing to . Finally, wrap the plastic around the cannula (4). A small cavity is formed that does not contain any minerals. This is when this cavity reaches its minimum size. So, before it joins with the cannula, the cannula must be pulled out. First, the cavity contains the final monomer mixture, i.e. the monomer with the highest refractive index. or filled with a monomer mixture. After that, the polymerization of the intermediate product becomes uniform. The polymerization reaction is carried out again until

The above description indicates that the refractive index distribution in the step index fiber is outwardly from the axis of the It is assumed that it is constantly decreasing.

According to this method, the refractive index distribution is reduced constant or parabolically, or The principle of step-index fibers even when reduced in the manner of Any type of optical fiber can be made accordingly. Poly inside tube (1) The polymer layer increases in refractive index from the tube (1) towards the axis of the intermediate workpiece. gradually become alarmed.

Ultraviolet irradiation of monomers can be carried out at any temperature, but The polymerization reaction was carried out with ultraviolet radiation by choosing a temperature that did not cause Experience has shown that temperatures below room temperature (20°C) are very effective.

The table below is an example of typical quantities of materials supplied to produce intermediate workpieces. Ru.

Monomer M1 High refractive index 0-100 mol% Monomer M2 Low refractive index 100-100 0 mol% UV reaction initiator 0.01-1 mol% Chain transfer agent 0.01-1 mol% Monomer M 1. As M2, reaction parameter = 1.0, i.e. r+ - r+ = 1 ．． Preferably, those with 0 are chosen, but the reaction parameters are not 1.0. It's okay.

At the same time, the difference in solubility parameters δ and δ2 of monomers M3 and M is greater than Δδ−1,0. The difference should not be too large, but this is not very important. This is because some monomer systems are large but nevertheless soluble.

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Claims (5)

[Claims] 1. In an intermediate workpiece having a graded refractive index, the intermediate workpiece has a graded refractive index. The refractive index n decreases from the rotational axis of the workpiece to the outer periphery of the intermediate workpiece. It consists of a polymer compound system, and the polymer in the intermediate product is composed of monomers and and/or the monomer mixture with the necessary additives while increasing the refractive index. or by discontinuous feeding, the monomers being irradiated and/or or has a graded refractive index characterized by being polymerized by radical polymerization. intermediate processed products. 2. Ultraviolet radiation (UV radiation) is used for the polymerization of monomers, its wavelength is 2 00 to 400 nm, preferably 300 to 400 nm. An intermediate processed product according to scope 1. 3. characterized in that an ultraviolet reaction initiator and/or a chain transfer agent is used in the polymerization. The intermediate processed product according to claim 1 or 2. 4. Organic peroxides and/or azo compounds are used in radical polymerization. An intermediate workpiece according to claim 1, characterized by: 5. Provide an outer tube (1) closed with end pieces (2' and 2''), and and the end pieces are rotated about a linear axis, after which the required additives are added. The nomer is supplied to the tube (1) through a cannula that moves back and forth, and the inner surface of the tube (1) is exposed to the air. coated with a layer of said monomer polymerized by radiation and/or radical polymerization; , the completed intermediate workpiece is moved from the outer periphery of the intermediate workpiece to the rotation axis of the intermediate workpiece. Continued polymerization, such as those made from polymers with increasing refractive index. A layer of the monomer is deposited continuously or discontinuously, and the intermediate product is made of a polymer. - withdrawing the cannula (4) from the intermediate workpiece before it is completely filled with After filling the cavity formed in the intermediate workpiece with the highest refractive index monomer, The gray according to any one of claims 1 to 4, characterized in that it undergoes polymerization. - A method for manufacturing an intermediate workpiece having a dead refractive index.