DE4135523A1 - PLASTIC LIGHTWAVE GUIDE - Google Patents

Abstract

In order to produce plastic optical waveguides having a high thermal resistance, a first coating of a reaction resin which is photoconductive in its cured state and which has the required mechanical properties is applied on a substrate material shaped as a glass or plastic fibre or as a bunble of such fibres. This reaction resin is cured to form a core of duroplastic material, a second coating made of a reaction resin which adheres well to the core material in its cured state and which has a refractive index at least 1 % lower than that of the core material is applied onto the first cured reaction resin, and the second reaction resin is cured to form a cladding made of duroplastic material.

Description

The invention relates to a method for producing Plastic fiber optic cables.

While opting for the telecommunications sector ter, d. H. Optical fibers made of quartz glass, provide short-range fiber optic cables made of plastics, d. H. polymer optical fiber (POF), an inexpensive alternative. Plastic light wave guide ter have a core / shell structure, the core of the best possible light-conducting, d. H. as low as possible damping, polymer material and the jacket consists of a Polymer material adhering well to the core with a refractive index dex, which is smaller than that of the core material.

In the production of plastic fiber optic cables from thermoplastic polymers, which expended in one The polymerization process leading to the most homogeneous possible Material leads, are manufactured. This thermoplastic Polymers are - in high purity conditions - in one Process the extrusion or melt spinning process into thin threads which represent the core (see: "Chemtronics", Vol. 1 (1986), pages 98-106). The coat also consists of thermoplastic material; he is mostly in a coextru sion process applied to the core. But it is described also the application from a solution (DE-OS 36 07 301). Serve as the core material in plastic optical fibers weighing thermoplastic (meth) acrylic ester polymers or copo  polymers; it also includes the use of deuterated and fluorinated (meth) acrylates described (DE-05 28 44 754). Polystyrene, styrene copolymers and polycarbonate are also used used as core material (see: "Plastics", Vol. 79 (1989), pages 1040 to 1044). As jacket materials mostly partially fluorinated acrylate or methacrylate polymers or fluorinated polyolefins used (DE-0S 36 07 301). There In addition, there are also plastic optical fibers with a silicone Sheath material known (DE-OS 38 14 298).

In addition to the cost-effective production, the advantages of Plastic fiber optic cables - compared to fiber optic cables tern in the form of optical glass fibers - especially in the simple ren manageability, because of the higher flexibility activity, even with larger fiber diameters. A serious one The disadvantage, however, is the limited thermal stability act. Due to the thermoplastic character are art fiber optic cables only below the glass temperature of the core materials can be used. At the for however, this means polymers that come into question an upper temperature limit of approx. 120 ° C. Because the requirements temperature resistance of plastic light waves however, ladders are becoming increasingly taller, for example with Use in the automotive sector, the provision is higher temperature-resistant plastic fiber optic cables urgently required.

Attempts have already been made to increase the temperature resistance plastic fiber optic cable made of thermosetting resin to produce compositions (EP-OS 02 46 613). This resin compositions used to manufacture the core hold a (meth) acrylic acid ester with a tricyclodecanyl group, a (meth) acrylic acid ester with an alkyl, cyclo alkyl or aryl group and a multifunctional monomer that serves for networking. The mixture of these three components  is pressed through a heated tube, polymerizing and a fiber is formed. The fiber product is then eats hardened, and the resulting core is then another coating applied. Such an approach is wise for procedural reasons for the Pra not very suitable, especially in economic terms.

The object of the invention is to provide a method that allowed, plastic optical fiber with high temperature stability in economic, d. H. procedural one easy way to manufacture.

This is achieved according to the invention in that on a Trä germ material in the form of a glass or plastic fiber or egg a bundle of such fibers from a first coating a reaction resin is applied, which in the hardened Zu is light-guiding and has the required strength features that this reactive resin to a core is hardened from thermosetting material that on the hardened Reaction resin tied a second coating of a reak tion resin is applied, which in the hardened state well on Core material sticks and a Bre that is at least 1% smaller index as the core material, and that this Re action resin to a jacket made of thermoset material is hardening.

In the method according to the invention, the fibers are made of glass or plastic essentially a carrier function, d. H. they are a processing aid for the applied reaction resins. However, these fibers can also be used for light conduction wear. The glass fibers are preferably made of quartz Plastic fibers preferably made of polyester or aramid, d. H. special polyamide. As a carrier in the fiction a single fiber, but it can also a fiber bundle can be used that consists of two or more  thin fibers. For example, in one Double crucible pulled several glass fibers and this then subjected together to a coating process.

In general, in the method according to the invention in the Proceeded in such a way that a thin Glass or quartz fiber is pulled, which then with a of the core or cladding materials listed below is layered. Through multiple coating thick re core or shell dimensions can be achieved. To cure depending on the type of art material, electric ovens or UV light sources.

In the process according to the invention, so-called reaction resins used, d. H. curable or crosslinkable resins. By Hardening of these resins creates plastics that are called thermosets be designated.

For the first coating process, i.e. H. for the production of the light-conducting core, are in the method according to the invention in principle, all reactive resins are suitable, on the one hand are sufficiently transparent and on the other hand those for one of the like coating process suitable viscosity, adhesion and Hardening characteristics and - in the hardened state - have the necessary strength properties. Principle Many of these are therefore also suitable for this purpose materials used to coat glass fibers with stu fen or gradient index profile can be used.

As particularly suitable for the method according to the invention have proven acrylic and methacrylate resins; such Resins are usually mixtures of mono- and di- or are polyfunctional components. (Meth) acrylate resins Esters of (meth) acrylic acid with mono- and di- or polyfunction light alcohols. Both aliphatic and cyclo come here  aliphatic as well as aromatic alcohols. Further are also fluorinated and deuterated (meth) acrylate resins Suitable for the production of core materials. Can be advantageous silicone (meth) acrylates are also used, in particular Dimethylpolysiloxane (meth) acrylates. To manufacture the core The resins can thermally, both with and without the addition of suitable peroxides, or - suitable when added neter photosensitizers - hardened by UV radiation will. Thermal addition-crosslinking silicones are also available Production of core materials suitable.

The reaction used in the second coating process After hardening, resins primarily need to form a coat material with a refractive index that is at least 1% smaller than the underlying core material. Are suitable therefore in principle all thermally or UV-curable reactions resins that meet this requirement. Suitable starting material rialien are in particular (meth) acrylate, the whole or can be partially fluorinated, as well as silicone (meth) acrylates. These resins can be thermally as well as UV-irradiated be hardenable. There are also addition-curing silicones applicable. In individual cases, this must be done for the jacket material applied reaction resin to the refractive index underlying core material can be coordinated.

The operating temperature of the plastic fiber optic cable the invention is -40 to 150 ° C or above. For protection the plastic fiber optic cable can be useful on apply a further coating to the coat. This can either - through a further coating process - a ge suitable reaction resin are applied, the following ge is hardened, or - by an extrusion process - a thermo plastic polymer.

The invention is intended to be described in more detail by means of exemplary embodiments  are explained.

For the production of a plastic optical fiber according to the Invention serves a fiber drawing machine. In this drawing machine a rod made of glass or quartz is con abge in a HF or electric furnace (made of graphite) lowers. The rod located in the heating zone becomes A thin glass fiber is drawn at the end, which serves as the carrier material serves. This glass fiber is then coated device for the core material and a first elec troofen or a first UV source and subsequently through a coating device for the jacket material so like a second electric furnace or a second UV source. The coated glass fiber is then ge on a drawing drum wraps. In front of the core material coater and after the second electric furnace or the second UV source is the thickness of the glass fiber or plastic light waves Conveniently kon with a fiber strength measuring device trolls.

Examples 1 to 5

A 90 µm thick fiber is drawn from a quartz rod. These Fiber is coated in a first coating device Reaction resin coated for the core material. After the hardness device that thermally in an electric furnace (500 W) or by UV radiation using a mercury vapor lamp (80 W / cm) takes place, a POF core with a diameter of 160 microns receive. This core is immediately in one second coating device with a reaction resin for the jacket material is coated, and then hardened. The respective jacket material is applied in one thickness brings that after curing a plastic fiber optic with an outer diameter of approx. 225 µm. The pull speed is approx. 0.2 m / s.  

In the plastic produced in the manner described At 835 nm, the attenuation behavior was made using optical fibers Room temperature checked. The results obtained as well the core and cladding materials used are in Table 1 summarized.

The values given in Table 1 show that by the he inventive method plastic fiber optic with tech nisch usable damping manufactured in a rational manner can be.  

Table 1

Claims (5)

1. A process for the production of plastic optical fibers, characterized in that a first coating of a reaction resin is applied to a carrier material in the form of a glass or plastic fiber or a bundle of such fibers, which is light-conducting in the hardened state and the required strength properties has that this reaction resin is cured to a core of thermosetting material, that a second coating of a reaction resin is applied to the hardened reaction resin, which adheres well to the core material in the hardened state and has a refractive index that is at least 1% smaller than that Core material, and that this Re aktionskär is hardened ge to a jacket made of thermosetting material. 2. The method according to claim 1, characterized records that as a reaction resin for the core material an acrylate or methacrylate resin or a silicone (meth) acrylic lat is used. 3. The method according to claim 1 or 2, characterized ge indicates that as a reaction resin for the man telmaterial an acrylate or methacrylate resin or a Sili Con (meth) acrylate is used. 4. The method according to any one of claims 1 to 3, characterized characterized that on the coat of duro plastic material is a coating made of a reactive resin applied and the reaction resin is cured. 5. The method according to any one of claims 1 to 3, characterized characterized that on the coat of duro plastic material applied a thermoplastic polymer becomes.