EP1325360A1

EP1325360A1 - Polycarbonate optical fibre

Info

Publication number: EP1325360A1
Application number: EP01982316A
Authority: EP
Inventors: Wolfgang Ebert; Hans-Josef Behrens; Heinz-Dieter Brandt; Thomas FÖLLINGER; Wilfried Haese
Original assignee: Bayer AG
Current assignee: Covestro Deutschland AG
Priority date: 2000-10-02
Filing date: 2001-09-19
Publication date: 2003-07-09
Also published as: JP2004525392A; DE10048796A1; WO2002029447A1; AU2002213936A1; US20050192425A1; TW556007B; US20040057693A1; WO2002029447A8

Abstract

The invention relates to a polycarbonate with a low particle content, to the use of said polycarbonate for producing optical fibres and to optical fibres comprising a core that contains said polycarbonate. The invention also relates to a method for producing said optical fibres, to the use of the optical fibres for transmitting optical signals in means of transport and to means of transport containing said optical fibres.

Description

optical fiber

The present invention relates to polycarbonate with a low particle content, the use of this polycarbonate for the production of light guides, light guides comprising a core, containing said polycarbonate, a process for

Production of said light guides, the use of said light guides for transmitting optical signals in means of transport, and means of transport containing said light guides.

Optical fibers are used to transmit optical signals. Light guides contain one

Core made of optically transparent material. The core can be made of glass or plastic, for example. The core is also called fiber. The core or the fiber can have any cross-section and diameter. In practice, the cross-section and diameter are selected in accordance with the technical requirements.

The core of the light guide is usually coated. The coating can be made of plastic or paint, for example. The coating offers some protection against mechanical effects on the core. The coating further improves the efficiency of the transmission of optical signals with the

Light guide. The mechanical and optical properties of the coating are therefore of particular importance.

This system of core and coating can be surrounded by a shell or a jacket. This serves, for example, to protect against damage and

Environmental influences.

The transmission of the optical signal, preferably by visible light, takes place in

Light guides take place primarily in the core. The optical properties of the core are therefore particularly important. It is particularly desirable that the core's attenuation coefficient be small so that signal transmission over long distances without too much loss of signal intensity.

Light guides comprising a polycarbonate fiber as the core are known. A disadvantage is the high damping coefficient of known polycarbonate qualities.

Light guides based on plastic-coated polycarbonate fibers are known from:

(a) EP-A 0 203 327;

() JP-A 84/216 104;

(c) JP-A 84/216 105;

(JP-A 84/218 404;

(e) JP-A 86/231 510;

(f> JP-A 86/240 206;

(g) JP-A 86/245 110;

(h) JP-A 86/278 807.

In these publications, light guides based on polycarbonate fibers are described, whose polycarbonate kera with certain fluorine-containing polymers ((a), (e), (f), (h)), with certain copolymers of methyl methacrylates, styrene or vinyl toluene and maleic anhydride (b), with certain copolymers on methyl methacrylates, methylstyrene and maleic anhydride (c), with certain copolymers of methyl methacrylate, α-methylstyrene, styrene and maleic anhydride (d) and with silicone resins, silicone-acrylate resins, urethane Acrylate resins, polyamides or poly-4-methylpentene-l

(g) are coated.

These plastics, which have hitherto been proposed for the coating of polycarbonate fibers, are disadvantageous because they have inadequate heat resistance (b), (c), (d), an insufficient elongation at break (b), (c), (d), (g) and / or have insufficient adhesion to the polycarbonate (a), (e), (f), (g), (h), for one application Too complex to manufacture on an industrial scale and therefore too expensive ((a), (e), (f), (h)), and / or lead to the formation of stress cracks in the polycarbonate core (g).

It is known to use UV-polymerizable mixtures of poly- and monofunctional acrylates or methacrylates for the coating of as

To use optical fibers to be used (see e.g. EP-A 0 125 710, EP-A 0 145 929, EP-A 0 167 199, DE-A 3 522 980).

These mixtures, which have been developed for the coating of glass fibers, are unsuitable for polycarbonate fibers because they lead to the formation of stress cracks in the polycarbonate core and, moreover, have a refractive index that is too high.

EP-A 0327 807 discloses light guides with a core made of polycarbonate and a coating made of polymerized acrylates and / or methacrylates.

The object of the invention is to provide polycarbonate, the damping coefficient of which is low, so that it can be used to produce high-quality light guides.

Furthermore, the object according to the invention is to comprise a light guide

To provide the core containing the polycarbonate according to the invention, and to provide a process for producing these light guides, and to provide means of transport containing the light guides according to the invention.

The advantageous properties of the polycarbonate fibers, in particular the high transparency, the high refractive index, the high heat resistance, the good mechanical properties, such as the high flexural strength and the high tensile strength and the low water absorption capacity, should not be impaired. It has now been found that the objects of the invention can be achieved with polycarbonate, the content of particles which are insoluble in polycarbonate does not exceed a certain level.

The object of the invention is achieved by polycarbonate containing less than 80,000 particles per gram of polycarbonate of particles insoluble in polycarbonate with a size of 0.3 to 10 μm, preferably less than 45,000 particles / g with a size of 0.3 to 0, 6 μm and less than 30,000 particles / g with a size of 0.6 to 1.0 μm and less than 3,000 particles / g with a size of 1.0 to 2.0 μm and less than 500 particles / g with a size Size of 2.0 to 5.0 μm and less than 200 particles / g with a size of 5.0 to 10 μm, particularly preferably less than 30,000 particles / g with a size of 0.3 to 0.6 μm and less than 20,000 particles / g with a size of 0.6 to 1.0 μm and less than 2,000 particles / g with a size of 1.0 to 2.0 μm and less than 300 particles / g with a size of 2.0 to 5.0 μm and less than 100 particles / g with a size of

5.0 to 10 μm, very particularly preferably less than 25,000 particles / g with a size of 0.3 to 0.6 μm and less than 10,000 particles / g with a size of 0.6 to 1.0 μm and less than 1,500 particles / g with a size of 1.0 to 2.0 μm and less than 50 particles / g with a size of 2.0 to 5.0 μm and less than 20 particles g with a size of 5 , 0 to 10 μm.

Furthermore, the object according to the invention is achieved by using the polycarbonate according to the invention for producing light guides.

Furthermore, the object of the invention is achieved by light guides comprising a core containing the polycarbonate according to the invention.

Light guides in which the core is coated are preferred.

Light guides in which the coating contains a polymer which contains repeating units derived from the monomers are particularly preferred one or more different compounds according to formula (I)

in the

m represents 2, 3 or 4,

D represents the m-valent radical of an aliphatic or aromatic hydrocarbon,

R is hydrogen or methyl,

Z, ∑2 and Z3 independently of one another for oxygen, sulfur, the -N (R) group (in which R is hydrogen or unsubstituted or substituted, preferably unsubstituted alkyl, aralkyl or aryl) or a divalent radical of the formula (II)

O O

II II

-Z-C— NH— A— NH— C— Z- (II)

stand in the

Means oxygen, sulfur or the -N (R) group, and A is an unsubstituted or substituted, preferably unsubstituted, divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon,

Z4 for oxygen, the divalent radical of the formula (II) or one of the following divalent radicals

O 0 O II II II -O— C— O— O-C-A, - C-O- - C— O- -NH-O

O O II 11

-NH— C— O - -C— H- NH— C— NH-,

A \, A2, A3 and A4 independently of one another represent an unsubstituted or substituted, preferably unsubstituted, divalent radical of an aliphatic, cycloaliphatic, aromatic-aliphatic or aromatic hydrocarbon,

n stands for zero or an integer from 1 to 20,

p, q and r can independently assume the value zero or 1 and

1 has a numerical value such that the weight-average molecular weight of the compound according to formula (I) is 450 to 5000, and

one or more different compounds according to formula (III) in the

R2 is hydrogen or methyl,

A5 an unsubstituted or substituted, preferably unsubstituted, divalent radical of an aliphatic or cycloaliphatic

Hydrocarbon means

Z5 and Z5 independently of one another for oxygen, sulfur or the -N (R ') -

Are groups in which R 'is H or unsubstituted or substituted, preferably unsubstituted alkyl, aralkyl or aryl, and

R3 is an optionally substituted alkyl, cycloalkyl or aralkyl radical.

Among the light guides mentioned, those in which Aj, A2, A3, A4 and A independently of one another represent an unsubstituted or substituted, preferably unsubstituted, divalent aliphatic or cycloaliphatic hydrocarbon radical are very particularly preferred.

Among the light guides mentioned, those in which

p and q have the value 1,

Z2 and Z3 mean oxygen, Z \ _ste for oxygen or the group OC NH A NH CO ht, in

O O or A is an unsubstituted or substituted, preferably unsubstituted, divalent radical of an aliphatic or cycloaliphatic C2-Cιg hydrocarbon, preferably the rest

Z4 for oxygen or the group

or O — CA ₃ -CO— _stands in the A3 an unsubstituted or substituted, preferably unsubstituted,

C2-C1 g radical of an aliphatic or cycloaliphatic hydrocarbon,

Ai is an ethylene or propylene-1,2 radical and

A2, A3 and A4 are independently unsubstituted or substituted, preferably unsubstituted, divalent radicals, preferably C2-Cg radicals, aliphatic or cycloaliphatic hydrocarbons. Also particularly preferred among the light guides mentioned are those in which in formula (III)

A5 is an unsubstituted or substituted, preferably unsubstituted, C2-C6 alkylene radical,

Z5 and Zg independently of one another represent oxygen or the -NH group and

R3 is a C 1 -C 4 -alkyl radical.

Also particularly preferred among the light guides mentioned are those in which in formula (III)

R3 is an unsubstituted or substituted, preferably unsubstituted, -CC-alkyl radical,

A5 for an ethylene residue and

Z5 stands for oxygen and Z for the -NH group.

It is preferred that, in the case of the coated light guides mentioned, the proportion of the repeating units derived from the monomers mentioned under A) in the polymer is 25 to 75% by weight and the proportion of the repeating units derived from the monomers mentioned under B) in the Polymer is 25 to 75% by weight and the sum of the proportions of the repeating units, derived from the monomers mentioned under A) and under B), in the polymer is 50 to 100% by weight, particularly preferably 100% by weight, is.

Furthermore, the object according to the invention is achieved by a method for producing the light guide according to the invention by coating the core of the

Light guide with a composition containing the monomers A) and B) and one or more different photoinitiators, the composition being polymerized on the core by UV rays.

A method is preferred in which the proportion of the photoinitiator in the composition is 0.1 to 10% by weight.

Furthermore, the object according to the invention is achieved by light guides obtained by the method according to the invention.

Furthermore, the object according to the invention is achieved by using the light guides according to the invention in means of transport.

Furthermore, the object according to the invention is achieved by means of transport comprising the light guide according to the invention.

The solutions to the problem according to the invention, which are the subject of the present invention, have numerous advantages. The advantageous properties of the polycarbonate fibers, as already mentioned, are not affected. They are even reinforced by the coating according to the invention in the light guides according to the invention. The optical, mechanical and thermal

Properties of the polycarbonates according to the invention and of the light guides according to the invention are very good. The polycarbonate according to the invention has a lower damping coefficient.

The curing speed of the coatings according to the invention is very high, which makes advantageous production possible.

The coatings according to the invention ensure that there is no stress cracking in the polycarbonate fiber. The use of the light guides according to the invention in transport means is advantageous because the light guides according to the invention enable a weight reduction compared to known light guides, for example those made of glass. They also have advantageous mechanical properties, in particular the light guides according to the invention are unbreakable in comparison with light guides made of glass. In addition, the light guides according to the invention enable significantly simplified handling and better connection technology. In automobiles, copper cables are common for signal transmission, compared to which a significant weight reduction is possible.

Vehicles in the sense of the present invention are in particular automobiles, rail vehicles, ships and airplanes.

The monomers for the coatings according to the invention are known or can be prepared by known processes. Some of them are commercially available.

For D, the tetravalent residues of aliphatic or aromatic hydrocarbons are, for example, the tetravalent aliphatic alcohols, e.g. Pentaerythritol, underlying hydrocarbon residues.

For D, the trivalent radicals of aliphatic or aromatic hydrocarbons are, for example, the aliphatic triols, such as glycerol, trimethylolethane, trimethylolpropane or hexanetriol, aromatic tricarboxylic acids, such as benzene-1,2,4-tricarboxylic acid or benzene-l, 3,5- tricarboxylic acid or aromatic triisocyanates, such as 2,4,6-tolylene triisocyanate or 4,4 ^I , 4 "-triphenylmethane triisocyanate, the underlying hydrocarbon radicals.

For D, A _j , A ₂ , A ₃ , A and A ₅ are optionally substituted divalent

Residues of aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbons, especially the aliphatic diols, such as ethylene glycol, 1,2-propanediol,

1,3-propanediol, 2,2-dimethyl-l, 3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-bu- tandiol, 1,4-butanediol, 1,5-pentanediol, 1,6- and 2,5-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, 2,2,4-trimethylpentanediol-1, 3, 2-methylpentanediol-2 , 4 and 2-ethylhexanediol-1, 3 or cycloaliphatic diols, such as 2,2-dimethyl-4,4-dimethyl-cyclobutanediol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-, 1, 3- and 1,4-cyclohexanediol, 1,4-bishydroxymethylcyclohexane, 2,2-bis (4-hydroxycyclohexyl) propane, 1-methyl-2,2-bis (4-hydroxycyclohexyl) ethane, 2 -Methyl-2,4- bis- (4-hydroxycyclohexyl) pentane and bis-hydroxymethyl-hexahydro-4,7-methanoindane, the underlying hydrocarbon radicals.

For A ₃ , the aliphatic dicarboxylic acids such as succinic acid, dimethylmalonic acid, glutaric acid, methyl succinic acid, adipic acid, dimethyl succinic acid, pimellic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid or dimer fatty acid or cycloaliphatic dicarboxylic acids, such as 1,2-dicarboxylic acids -, 1,4-cyclohexanedicarboxylic acid, and aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene 1,2-, -1,4-, -1,5-, -1,8-dicarboxylic acid,

5-methylisophthalic acid, tetrahydrophthalic acid and hexahydroendomethylenetetra-hydrophthalic acid, the underlying hydrocarbon radicals.

For A, the optionally substituted, divalent aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon radicals are, above all, the aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene 1,6-diisocyanate, cycloaliphatic diisocyanates such as cyclohexane-1,4-diisocyanate and cyclopentane , 3-diisocyanate, methylene bis (4,4'-cyclohexyl) diisocyanate and 1-isocyanatomethyl-5-isocyanato-l, 3,3-trimethylcyclohexane, and aromatic diisocyanates such as 2,4- and 2 , 6-tolylene diisocyanate, 3,3'-dimethyl-4,4 ^, -diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate and 4,4'-diphenyl ether diisocyanate, the underlying hydrocarbon radicals.

For R ₃ are as optionally substituted alkyl radicals such as methyl, ethyl, propyl, n-butyl, sec.-butyl, i-propyl, tert.-butyl, i-butyl, pentyl, i-pentyl, neopentyl, Heptyl, n-hexyl, 2-ethyl-hexyl, nonyl, decyl, cetyl, Dodecyl and stearyl radicals, as cycloaliphatic radicals, cyclopentyl and cyclohexyl radicals optionally substituted by methyl groups. The araliphatic radicals are, above all, the benzyl radical and benzyl radicals substituted by methyl and lower alkoxy groups.

The compounds of formula (I) (polyfunctional acrylic acid derivatives or methacrylic acid derivatives) are compounds containing ether, ester, urethane and / or urea groups. It is preferably polyethers and / or polyester polyols reacted with acrylic acid derivatives or methacrylic acid derivatives.

Compounds of the formula (III) (monol-unfunctional acrylates or methacrylates) are with acrylic acid esters or methacrylic acid esters which additionally have an ester, urethane and / or urea group.

The polycarbonates according to the invention can contain conventional additives.

The light guides according to the invention can contain further constituents. For example, they can contain adhesion-promoting intermediate layers. For example, they can contain protective cladding layers, especially those that are flexible but resistant to aqueous solutions as well as mineral oils and fuels, such as e.g. thermoplastic polyurethanes and rubbers.

The coatings according to the invention can contain customary additives.

In addition to components A and B, the coatings according to the invention can contain conventional additives such as e.g. Solvents that are inert to polycarbonates, contain polymerization inhibitors, antioxidants, etc.

Photo initiators are known and customary in the trade. Examples of photoinitiators include: benzoin, benzoin ethers, benzyl ketals, benzophenone, thioxanthone and the derivatives thereof, for example benzyl ethyl ketal and 2-hydroxy-2-methyl-l-phenyl-propan-1-one.

Polycarbonates and the common processes for their production are e.g. in "Chemistry and Physics of Polycarbonates" Polymer Rev. Vol. 9, Interscience Publishers. You can add known chain terminators if necessary (see e.g. EP-A 0 010 602, DE-A 3 143 252). Branching agents such as trisphenols and / or isatin biscresol (phenol) (see, for example, DE-A 1 570 533, DE-A 1 595 762, DE-A 2 500 092), stabilizers such as phosphines and / or phosphites (see, for example, EP-A 0 143 906, DE-A 21 40207) and mold release agents (see, for example, DE-A 2 507 748, DE-A 2 729 485 and DE-A 2 064 095). The polycarbonates are preferably worked up in a known manner by precipitation, spray evaporation or extrusion. The relative viscosity of a 0.5% solution of the polycarbonate in methylene chloride at 25 ° C. is preferably between 1.18 and 1.32.

Particularly preferred polycarbonates are the homopolycarbonate based on bisphenol A, the homopolycarbonate based on l, l-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, the homopolycarbonate based on one of the following bisphenols

and the copolycarbonates from combinations of the bisphenols mentioned, in particular the copolycarbonate based on the two monomers bisphenol A and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

The homopolycarbonate based on bisphenol A is very particularly preferred.

The polycarbonate preferably has a heavy metal content of less than 5 ppm, particularly less than 3 ppm, very particularly less than 0.5 ppm. Low heavy metal contents result in less optical attenuation in the light guide.

The polycarbonate can be made by known methods, e.g. after this

Phase interface process from bisphenol and phosgene or by the melt transesterification process from carbonic acid ester and bisphenol.

The polycarbonate with a lower particle content according to the invention is preferably produced as follows. Raw materials and solvents are filtered through filters, preferably with pore sizes of 0.25 to 15 μm, particularly preferably 0.5 to 5 μm. Spinning, granulation and handling of the polycarbonate must take place under clean conditions (clean room) with the exclusion of dust.

The viscosity of the compositions to be applied to the polycarbonate fibers according to the invention and polymerizable by UV rays can be selected by the choice of Molecular weight of components A and B and / or varied within wide limits by the ratio of components A and B and adjusted to the intended spinning speeds and spinning temperatures of the polycarbonate fibers. The compositions to be used according to the invention preferably have a viscosity of 500 to 10,000 cP at 25 ° C. The compositions to be used according to the invention can preferably be processed at temperatures from 15 to 140 ° C.

In terms of the process, the polycarbonate core of the light guide of the polycarbonate fibers can first be produced and later with those to be applied according to the invention

Coating materials are provided. However, it is more advantageous to apply the coating immediately after the polycarbonate fiber has been produced. The thickness of the coating to be applied to the polycarbonate fiber according to the invention is preferably less than 50 μm.

The light guides according to the invention can be processed into single-core or multi-core cables by the light guides individually for themselves or a plurality of light guides combined into a bundle with further polymer layers, e.g. by coextrusion. The polymer layer is preferably a thermoplastic elastomer.

The light guides can be glued into a bundle.

The diameter of the light guide is preferably between 0.05 mm to 5 mm, particularly preferably 0.1 mm to 3 mm, very particularly preferably 0.25 to 1.5 mm.

The light guides according to the invention can also be used as lighting elements. For this, the surface of the light guide is at the desired

Spot damaged. This couples light. Alternatively, the light can be directed to the desired location to be illuminated. For example, you can fittings, for example in electronic devices such as radios or computers, are illuminated.

Examples 1 to 12 (coated light guides)

Examples 1 to 8 are according to the invention.

Examples 9 to 12 (mixtures 9 to 12) are comparative examples (comparative mixtures).

A polycarbonate fiber according to the invention (diameter: 1.0 mm) was pulled vertically from top to bottom centrally through a vessel which had a nozzle (diameter: 1.2 mm) at its bottom. The vessel was filled with one of the coating mixtures described below. By between

Thread and nozzle remaining annular gap, the fiber was evenly coated with the mixture in question.

A 20 cm long medium pressure mercury lamp (power: 120 W / cm) was located below the coating vessel, parallel to the thread

Parabolic mirror was focused on the thread in order to obtain the highest possible light output for the UV polymerization of the coating mixtures.

After passing a deflection roller, the coated thread was wound on a large drum, which ensured that the thread was pulled through the system by means of a motor drive, the speed being a constant 5 m / min.

The thickness of the coating applied to the polycarbonate thread was 10 to 30 μm in all cases.

The polycarbonate fibers obtained, provided with a UV-polymerized coating, were stored for 1 month at room temperature and then checked for any damage to the polycarbonate core, for example due to stress cracks. The results obtained with the individual mixtures and the compositions of the mixtures are summarized in Table 1 below. Table 1

Annotation:

All mixtures 1 to 12 contained 3 parts by weight of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

The maximum curing rate of the individual mixtures was determined in the simplified manner described below on coated films; however, the results obtained on the films are readily transferable to fibers. The mixtures were applied to a polycarbonate plate using a doctor blade (film thickness: 50 μm). The coated polycarbonate sheets were carried out on a belt at a certain speed under a UV irradiation system (UV laboratory device from U. Steinemann AG; 80 W / cm). The belt speed just permissible for the hardening of the respective mixture was determined (= maximum belt speed [m / min]).

The reaction products a to h used as component A in mixtures 1 to 12 were obtained as follows:

Implementation product a:

500 g of a linear polyether (average molecular weight: approx. 1,000; reaction product of 1,2-propanediol with propylene oxide), 167 g of 2-hydroxyethyl acrylate, 0.5 were placed in a 2-liter flask equipped with a stirrer, thermometer and gas inlet tube g Desmorapid SO and 0.3 g p-methoxyphenol submitted. At 60 to 65 ° C and with passage of dry air, 265 g of isophoronedi- Isocyanate added dropwise. The reaction mixture was then stirred at 60 to 65 ° C until the NCO number had dropped below 0.1%.

Reaction product b: 500 g of a linear polyester having OH groups (average molecular weight: 1,000; OH number 112; reaction product of adipic acid and neopentyl glycol), 255 g of 2-hydroxyethyl acrylate and 350 g of isophorone diisocyanate were used in the reaction product for reaction a) described way implemented.

Implementation product c:

500 g of unbranched, hydroxyl-containing polyester (average molecular weight: 2,250); Reaction product from adipic acid and butanediol), 300 g of 2-hydroxyethyl acrylate and 335 g of isophorone diisocyanate were reacted in the manner described for the reaction product a).

Implementation product d:

500 g of a linear polypropylene glycol (average molecular weight: 2,000), 250 g of 2-hydroxyethyl acrylate and 290 g of isophorone diisocyanate were reacted in the manner described for the reaction product a).

Implementation product e:

500 g of a linear polyester containing hydroxyl groups (average molecular weight: 1,000; OH number 112; reaction product of adipic acid and neopentyl glycol), 40 g of acrylic acid, 2 g of p were placed in a 1 liter flask equipped with a stirrer, thermometer, gas inlet tube and water separator -Toluenesulfonic acid, 0.3 g of p-methoxyphenol, 0.3 g of di-tert-butyl hydroquinone and 190 g of toluene and heated to reflux while passing air. After the theoretical amount of water had been split off, the toluene was distilled off in vacuo.

The product obtained was then in a with stirrer, thermometer and

Gas inlet pipe provided 1 1-flask filled and with 0.1 g Desmorapid SO as well as 0.05 g of di-tert-butyl-quinone and heated to 60 to 65 ° C. At this temperature, 50 g of isophorone diisocyanate are added dropwise while passing dry air through. The reaction mixture was then stirred at 60 to 65 ° C until the NCO number had dropped below 0.1%.

Implementation product f:

500 g of a linear polyether containing hydroxyl groups (average molecular weight: 1,000; reaction product of propanedio-1,2 with propylene oxide), 40 g of acrylic acid, 2.7 g of p-toluenesulfonic acid, 0.3 g of p-methoxyphenol, 0.3 g of di- Tert-butyl hydroquinone and 190 g of toluene were reacted in the manner described for the reaction product e) and, after the toluene had been distilled off, also reacted with 50 g of isophorone diisocyanate as described for the reaction product e).

Reaction product g: 600 g of a linear hydroxyl-containing polyester (average molecular weight: 2,000; reaction product of adipic acid with ethylene glycol, diethylene glycol and butanediol), 22.7 g acrylic acid, 3.1 g p-toluenesulfonic acid, 0.3 g p-methoxyphenol, 0 , 3 g of di-tert-butyl hydroquinone and 220 g of toluene are reacted in the manner described for reaction product d) and, after removal of the toluene, are also reacted with 31.6 g of isophorone diisocyanate as described for reaction product e).

Implementation product h:

500 g of a linear polyether containing hydroxyl groups (average molecular weight: 1,000; reaction product of 1,2-propanediol with propylene oxide), 500 g

2-hydroxyethyl acrylate and 590 g of isophorone diisocyanate are reacted under the conditions described for reaction product a).

The attenuation coefficient of the light guide according to Example 1 was measured for three different polycarbonates (different particle content). The following results were obtained: Example 13 (according to the invention; particles each per 1 gram of polycarbonate)

Particles 0.6-1.0 μm: 47 200 particles 1.0-2.0 μm: 3 100 particles 2.0-5.0 μm: 160 particles 5.0-10 μm: 40

Attenuation coefficient, measured at 660 nm: 2.3 dB / m

Example 14 (according to the invention; particles each per 1 gram of polycarbonate)

Particles 0.6-1.0 µm: 21,300

Particles 1.0-2.0 µm: 2200 Particles 2.0-5.0 µm: 310

Particles 5.0-10 µm: 90

Attenuation coefficient, measured at 660 nm: 1.3 dB / m

Example 15 (comparison; particles each per 1 gram of polycarbonate)

Particles 0.6-1.0 µm: 170400

Particles 1.0-2.0 µm: 21,700

Particles 2.0-5.0 µm: 1,700 particles 5.0-10 µm: 400

Attenuation coefficient, measured at 660 nm: 3.2 dB / m

The damping coefficient was measured according to the method described in Tamaka et. al., "Fiber other Integrated Optics", Volume 7, page 139 (1987). The particle number in polycarbonate was measured using the "Hiac / Royco 346 BCL" device. This is a laser scanning device. Measurements were made on a 2% solution in methylene chloride for particle measurement up to 10 μm and on a 5% solution for particle measurement above 10 μm. The measurement was carried out using the method described in US Pat. No. 5,073,313 and in EP-A 0 379 130.

Claims

Patent claims

1. Polycarbonate containing less than 80,000 particles per gram of polycarbonate of polycarbonate-insoluble particles with a size of 0.3 to 10 μm.

2. Use of the polycarbonate according to claim 1 for producing light guides.

3. Light guide comprising a core containing the polycarbonate according to claim

1.

4. Light guide according to claim 3, wherein the core is coated.

5. Light guide according to claim 4, wherein the coating contains a polymer which

Contains repeating units derived from the monomers

A) one or more different compounds according to formula (I)

(I) in the

m stands for 2, 3 or 4,

D represents the m-valent residue of an aliphatic or aromatic hydrocarbon, Rj is hydrogen or methyl,

Z\, Z2 and Z3 independently represent oxygen, sulfur, the -N(R) group (in which R is hydrogen or unsubstituted or substituted alkyl, aralkyl or aryl) or a divalent radical of the formula (II)

O O

II II _τn

— ZC— NH— A-NH— CZ— ^U stand, in the

Z means oxygen, sulfur or the -N(R) group, and

A an unsubstituted or substituted divalent

is the residue of an aliphatic, cycloaliphatic, araliphatic or aromatic hydrocarbon,

Z4 for oxygen, the divalent radical of formula (II) or one of the following divalent radicals

O 0 O

II O

II II II ⁰

0— c— 0- O-C-A. -C-O- — C— o- -NH-C-

fl fl fl

-NH— CO— _f — C-NH- _; -NH— C-NH- stands,

A\, A2, A3 and A4 independently represent an unsubstituted or substituted divalent radical of an aliphatic, cycloaliphatic, aromatic-aliphatic or aromatic hydrocarbon means,

n represents zero or an integer from 1 to 20,

p, q and r can independently assume the value zero or 1 and

1 has such a numerical value that the weight average molar mass of the compound according to formula (I) is 450 to 5000, and

one or more different compounds according to formula (III)

OII

CH 2==CC— O— Ar 5 -CZ _R -R,

R, (Hl),

in the

R2 is hydrogen or methyl,

A5 represents an unsubstituted or substituted divalent radical of an aliphatic or cycloaliphatic hydrocarbon,

Z5 and Zg independently represent oxygen, sulfur or the -N(R') groups in which R ¹ is H or unsubstituted or substituted alkyl, aralkyl or aryl, and

R3 is an unsubstituted or substituted alkyl, cycloalkyl or aralkyl radical.

6. Light guide according to claim 5, wherein Aj, A ₂ , A3, A4 and A independently represent an unsubstituted or substituted, divalent aliphatic or cycloaliphatic hydrocarbon radical.

7. Light guide according to claim 5, wherein

p and q have the value 1,

Z2 and Z3 mean oxygen,

Z\ for oxygen or the group O— C-NH-A— NH-C-O

O O stands, in which A is an unsubstituted or substituted, divalent radical of an aliphatic or cycloaliphatic C2-Cχg-carbon hydrogen,

Z4 for oxygen or the group

or O CA ₃ — CO— _stands)

O O in which A3 is an unsubstituted or substituted C2-Cι residue of an aliphatic or cycloaliphatic hydrocarbon,

A\ is an ethylene or propylene-1,2 residue and A2, A3 and A4 are independently unsubstituted or substituted, divalent radicals, preferably C2-Cg radicals, aliphatic or cycloaliphatic hydrocarbons.

8. Light guide according to one of claims 5 to 7, wherein in formula (III)

A5 is an unsubstituted or substituted C2-C6 alkylene radical,

Z5 and Zg independently stand for oxygen or the -NH group and

R3 is a Cι-Cχ alkyl radical.

9. Light guide according to one of claims 5 to 8, wherein in formula (III)

R3 represents an unsubstituted or substituted Cι-C5 alkyl radical,

A5 for an ethylene residue and

Z5 stands for oxygen and Z5 stands for the -NH group.

10. Light guide according to one of claims 5 to 9, wherein the proportion of repeating units derived from the monomers mentioned in claim 5 under A) in the polymer is 25 to 75% by weight and the proportion of repeating units derived from those in claim 5 monomers mentioned under B), in the polymer is 25 to 75% by weight and the sum of the proportions of the repeating units, derived from the monomers mentioned in claim 5 under A) and under B), in the polymer is 50 to 100% by weight. -% amounts.

11. A method for producing the light guide according to one of claims 3 to 10, by coating the core of the light guide with a composition containing the monomers A) and B) and one or more different photoinitiators, the composition polymerizing on the core by UV rays becomes.

12. The method according to claim 11, wherein the proportion of the photoinitiator in the composition is 0.1 to 10% by weight.

13. Light guide obtainable by the method according to claim 11 or 12.

14. Use of the light guide according to one of claims 3 to 10 or according to claim 13 in means of transport.

15. Transport means containing the light guide according to one of claims 3 to 10 or according to claim 13.