AU601072B2 - Aromatic ester carbonate polymer optical waveguides - Google Patents

Description

i AU-AI-21348/88 PCI WORLD INTELLECTUAL PROPERTY ORGANIZATION PC n l .nllo reau r INTERNATIONAL APPLICATION PUBL j NDI T PA NT PERATION TREATY (PCT) (51) International Patent Classification 4 (1I) !nternational Publication Number: WO 88/ 10438 G02B 6/00 Al (43) International Publication Date: 29 December 1988 (29.12.88) (21) International Application Number: PCT/US88/02128 (22) International Filing Date: (31) Priority Application Number: (32) Priority Date: (33) Priority Country: 23 June 1988 (13,06.88) 065,973 24 June 1987 (24.06.87)

US

(71) Applicant: THE DOW CHEMICAL COMPANY [US/ US]; 2030 Dow Center, Abbott Road, Midland, MI 48640 (US).

(72) Inventors: PARKER, Theodor, L. 20 Topinera Lane, Lafayette, CA 94549 PEDERSEN, David, R.

3640 Morgan Territory Road, Clayton, CA 94517

(US),

(74) Agent: KARADZIC, Dragan, The Dow Chemical Company, P.0, Box 1967, Midland, MI 48641-1967 n-B-ra-- '---iPw zar1~:xiw!ls i r :rinting (81) Designated States: AT (Europen patent), AU, BE (European patent), CH (European patent), DE (European patent), FR (European pati GB (European patent), IT (European patent), JP, KR, LU (European patent), NL (European patent), SE (European patent).

Published With international search report.

P I AR 989

AUSTRALIA)'

19 JAN 1989 PATENT OFFICE sYIILi~PYWI LYYIUI~ sCYCWPYW~~"~U" I (54) Title: AROMATIC ESTER CARBONATE POLYMER OPTICAL WAVEGUIDES (57) Abstract The invention is a polymer optical waveguide which comprises; a core comprising an aromatic ester carbonate or a blend of an aromatic ester carbonate with a bisphenol based polycarbonate; and a clad of a polymer which adheres to the core and has a lower refractive index than the aromatic ester carbonate or the blend of an iromatic ester carbonate and a bisphenAl based polycarbonate wherein said optical waveguide transmits light through the core.

i -re i I

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WO 88/10438 PCT/US88/02128 -1- AROMATIC ESTER CARBONATE POLYMER OPTICAL WAVEGUIDES This invention relates to novel polymer optical waveguides with higher use temperatures than previously known for polymer optical waveguides. More partioularly, these polymer optical waveguides are based on aromatic ester carbonates.

Polymer optical waveguides are generally comprised of optically clear polymers which transmit light. Such waveguides may be of various shapes.

Generally, a polymer optical waveguide comprises a core of a material which transmits light, and a clad over the core which has a different refractive index than the core where the difference is such that the light 1 waves do not pass through the cladding but instead are reflected back into the core of the waveguide. The light transmitted down polymer optical waveguides can be used for illumination or data transmission. In illumination uses, the optical waveguides are used to light up signs, in decorative objects and can be used to light up certain functional apparatus such as the dashboard of an automobile. Polymer optical waveguides must be optically clear with low attenuation, that is, little light loss as the lght is transmitted down the r WO 88/10438 PCT/US88/02128 -2fiber, Furthermore, polymer optical waveguides must withstand handling and bending during processing of the waveguides.

Commercially used polymer optical waveguides zener ,.ly comprise cores of acrylics or styrenics, with claddings of acrylics or fluoropolymers. These materials generally have a relatively low use temperature, for example less than 90 0 C, and low resistance to harsh environments such as high humidity environments. In many potential uses for polymer optical waveguides, the polymers are exposed to high temperatures and/or harsh environments, i.e. humid environments. The present polymer optical waveguides are nct able to tolerate such conditions.

What is needed is a polymer optical waveguide which is useful at higher temperatures and has a greater resistance to harsh environments. What is further needed is such a polymer optical waveguide with low attenuation.

The invention is a polymer optical waveguide which comprises: a core comprising an aromatic ester carbonate or a blend of an aromatic ester carbonate with a bisphenol based polycarbonate; and a clad of a polymer which adheres to the core and has a lower refractive index than the aromatic ester carbonate or the blend of an aromatic ester carbonate and a bisphenol based polycarbonate I WO 88/10438 PCT/US88/02128 -3wherein said optical waveguide transmits light through the core.

The polymer optical waveguides of this invention are useful at higher temperatures than presently known optical waveguides. These polymer optical waveguides demonstrate low attenuation and are much more resistant to humidity and other hostile environments. Furthermore, these polymer optical waveguides demonstrate good ductilLty and are able to withstand normal handling and bending during fabrications of devices from polymer optical waveguides.

An aromatic ester carbonate comprises a polymer with ester and carbonate functional groups, or linkages, along the backbone of the polymer, wherein such functional or linking groups link hydrocarbylene moieties. Preferably, the hydrocarbylene moieties 2 comprise arylene and the residue of bisphenolic compounds. Ester linkage refers herein to a functional group along the backbone of the polymer which corresponds to the formula 0 Carbonate moieties as used herein refer to functional groups or linkages along the backbone of the polymer 0 -0-C-O- Herein, core and claddings are often referred to and described by the percentage of ester and WO 88/10438 PCT/US88/02128 carbonate linkages in the backbone of the polymer. A particular core or clad with a stated percentage of carbonate or ester linkages may comprise a copolymer with the stated percentage of ester and carbonate linkages in the backbone, or it may be a blend of an aromatic ester carbonate and a polycarbonate to create a blend with the stated percentage of ester and carbonate linkages in the total blend. For the purposes of this invention, a copolymer with a stated ester and carbonate percentage in the backbone of the polymer is equivalent to a blend with the same percentage of ester and carbonate linkages.

Arylene refers herein to moieties which comprise aromatic moieties with two bonds. Examples of such moieties include pheny.ene and biphenylene moieties. Phenylene moiety as used herein refers to ortho; meta, and para phenylene linkages, wherein meta and para linkages are preferred and most commonly found. Preferably, the phenylene moiety is a mixture of the residue of terephthalic and isophthalic acid.

Preferably, the percentage of terephthalic acid to isophthalic acid moieties is from 80:20 to 20:80, more preferably from 80:20 to 50:50, and most preferably from 80:20 to 70:30. Percentages of ester to carbonate linkages are based on mole percent. The bisphenol moieties in the backbone of the aromatic ester carbonates may be the residue of any bisphenolic compound which may be reacted to prepare an aromatic ester carbonate. The polycar-bonates which may be blended with an aromatic ester carbonate to get a particular percentage of ester and carbonate linkages 3 in the material, may be any bisphenolic based polycarbonate. Preferably, the aromatic ester WO 88/10438 PCT/US88/021 28 carbonate comprises units which correspond to the formula 0 0 0 1I II II (R -OCR CO) (R 1 0CO) wherein R1 is the residue of a bisphenol moiety;

R

2 is arylene; and z is a positive real number such that the molecular weight of the aromatic ester carbonate is between 4,000 and 200,000; wherein the ratio of x to y is between 0.0025 ar'd In the hereinbefore presented formulas, R 2 is preferably phenylene. Preferably, z is a positive real number such that the molecular weight of the aromatic ester carbonate is between 10,000 and 100,000, and even more preferably between 15,000 and 45,000.

The polycarbonates which may be blended with the aromatic ester carbonates may be any polycarbonates known to the skilled artisan which will blend with the particular aromatic ester carbonate used. The bisphenolic based polycarbonates are preferred and more preferred polycarbonates comprise units which correspond to the formula wherein WO 88/10438 PCT/US88/02128 -6- 0 R3

R

3

R

3 at, each occurrence is independently H, Cl, Br, or CI-C 4 alkyl; R4 is a direct bond, carbonyl, -S02-, a

C

1

-C

12 divalent hydrocarbon, a CI-C 6 divalent fluorocarbon radical, or inertly substituted CI-C 6 divalent hydrocarbon radical; and t is independently in each occurrence an integer of between 16 and 800.

The bisphenols whose residues are found in the aromatic ester carbonate, i.e. R1, preferably correspond to the formula R3 R3 0

R

40

R

3

R

3 wherein WO 88/10438 PCT/US88/02128 -7-

R

3 is independently at each occurrence H, Cl, Br, or CI-C 4 alkyl; and

R

4 is independently at each occurrence a direct bond, a carbonyl, -SO2-, a C0-C 6 divalent hydrocarbon, a CI-C6 divalent fluorocarbon radical, or an inePtly substituted CI-C 6 divalent hydrocarbon radical.

R

3 is preferably hydrogen or C 1 4 alkyl, more preferably hydrogen or methyl, and most preferably hydrogen. R 4 is preferably C 1 6 hydrocarbylene, a direct bond, oxygen, or C1-6 perfluorohydrocarbylene.

Even more preferably, R4 is C1- alkylidene, oxygen,

CI.

6 perfluoroalkylidene, or a direct bond. Even more prefePably, R4 is isopropylidene, CH 2 oxygen, C(CF 3 2 or a direct bond. Most preferably, R 4 is isopropylidene. The most preferred bisphenol moiety is a bisphenol A moiety.

Aromatic ester carbonates useful in this invention preferably have a total mole percent of ester linkages of between 0.5 and 95 percent, more preferably between 1 and 80 percent, and most preferably between and 75 percent.

Aromatic ester carbonates and their preparation are well known in the art. See, for example, U.S.

Patent 4,330,662. The polycarbonates useful in this invention and their preparation are well known in the art. See, for example, Encyclopedia of Polymer Science and Technology, editor Mark et al,, Interscience Division of John Wiley and Sons, New York, New York, 1969, Volume 10, pages 714-725. Blends of aromatic ester carbonates and polycarbonates may be prepared by I_ __J 8 methods well known In the art, preferred methods include solution and melt blending, The core of the polymer optical waveguides of this invention comprises an aromatic ester carbonate copolymer, or a blend of aromatic ester carbonates with polycarbonates. Such a core comprises the percentages of ester to carbonate linkages described hereinbefore, Such a core must bl able to transmit light with acceptable attenuation for the particular use, One skilled in the art would recognize that the acceptable attenuation level is dependent upon the particular use to which the optical waveguide is put. Generally, the higher the ester linkage percentage, the higher the use temperature.

A clad useful in the polymer optical waveguides of this invention can be any polymer which adheres to the core polymer and has a lower refractive Index than the aromatic ester carbonate or blend of the aromatic ester 15 carbonate and bisphenol based polycarbonate, The adhesion must be such that during either use or handling of the optical waveguides, the cladding *0 does not separate from the core. The polymer used for the cladding must have a lower refractive index so that light passes through the core and is reflected or refracted in the direction of the core. The cladding therefore functions to reflect the light back into the core of the optical waveguide so that it may continue to pass through the core, Preferably, the difference in refractive index between the core and the clad Is 0.016 or above. Preferable polymers useful as claddings comprise acrylics, aromatic ester carbonates, a blend of an aromatic ester carbonate with a polycarbonate, a polycarbonate, an imidized acrylic based polymer, or a °oS

S

MRC/8549N -h WO 88/10438 PCT/US88/0212r -9fluoropolymer. The aromatic ester carbonates and blends of aromatic ester carbonates with polycarbonates wherein the ester linkage percentage is lower than that of the core will have a lower refractive index than that of the core, and thus be preferred for use as claddings in this invention. Such difference must be sufficient so that the light waves are reflected back into the core from the cladding. The choice of the particular polymer to be used as a cladding is dependent upon the particular composition of the core and the desired use temperature for the polymer optical waveguide. The polycarbonates useful for clads in this invention include those polycarbonates d&-cribed hereinbefore. Fluoropolymer refet's herein to polymers derived from monomers comprising unsaturation with fluorine substitution on the unsaturated carbons, and acrylics with fluorine suostitution on saturated or unsaturated carbons. Preferred fluoropolymers include fluoroolefins and fluorinated acrylics. More preferable fluQropolymer clads include vinylidine fluoride based polymers or copolymers of vinylidine fluoride with tetrafluoroethylene or hexafluoropropylene. Preferred fluorinated acrylics include 25 fluorinated polyalkylacrylates and fluorinated polyalkylmethacrylates. More preferred fluorinated acrylics include fluorinated polytrifluoro ethyl methacrylates or fluorinated polyalkylmethacrylates, Imidized acrylic based polymers include those described in U.S. Patent 4,2 4 6, 37 4. Preferred acrylics include polymers which comprise 50 percent or more of polyalkylaorylates and polyalkylalkacrylates. More preferred acrylics include the polyalkylmethacrylates.

Most preferred acrylics include polymethylmethacrylates. In the embodiment wherein the polymethyl- WO 88/10438 PCT/US88/02128 methacrylate is used in higher temperature use oa-".al waveguides, the polymethylmethacrylate is preferabt,, a syndiotactic polymethylmethacrylate. Such syndiotactic polymethylmethacrylates are available from Rohm Corporation under the designation Rohm 8678 and Rohm 8H. The claddings of imidized acrylic based polymers, aromatic ester carbonates, and blends'of aromatic ester carbonates with polycarbonates generally have higher use temperatures than do the acrylics or fluoropolymers, In one preferred embodiment, the polymer optical waveguides of this invention comprise a core of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a inole peCen-t polycarbonate wherein the total Lmnr of ester linkages in the core is between 50 percent and percent, with the remaining linkages being .carbonate linkages; and a clad of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total 4~m~en 1 of ester linkages in the clad is between 0,5 percent and percent, with the remaining linkages being carbonate linkages, or syndiotactic polymethylmethacrylate.

More preferably, such polymer optical waveguide comprises a core of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total z 4 e ester linkages in the core is between 50 percent and I i WYO 88/10438' PCT/US88/02128 -17percent, with the remaining linkages being carbonate linkages; and a clad of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a rmcAle perc:A:-^ polycarbonate wherein the total .anmG.fof ester linkages in the clad is between 0.5 percent and percent, with the remaining linkages being carbonae linkages, or syndiotactic polymethylmethacrylate.

The polymer optical waveguides of this embodiment preferably have a use temperature of 140 0 C or above.

Use temperature means herein that the polymer optical waveguide can be used at or above the stated temperature for extended periods without the polymer or the optical waveguid? undergoing significant degradation.

In another preferred embodiment, the polymer optical waveguide comprises a core which comprises an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total am of ester linkages in the core is between percent and 50 percent, with the remaining linkages being carbonate linkages; and a clad which comprises an acrylic, an imidized acrylic based polymer, or a fluoropolymer.

Even more preferably in this embodiment, the polymer optical waveguide comprises i I WO 88/1:0438 PCT/US88/02128 -12the core comprises an aromatic ester carbonate or a blend of an aromatic ester carbonate and a role percenT polycarbonate wherein the total amffe~ftof ester linkages in the core is between 1 percent and 25 percent, with the remaining linkages being carbonate linkages; and a clad which comprises an acrylic, an imidized acrylic based polymer, or a fluoropolymer, And even more preferably, such polymer optical waveguide comprises a core which compriser n aromatic ester carbonate, or a blend of an aromatic ester carbonate and a Polycarbonate, wherein the mo total amhn of ester linkages in the core is between 1 percent and 5 percent, with the remaining linkages being carbonate linkages; and a clad which comprises an acrylic, an ifidized acrylic based polymer, or a fluoropolymer.

A most preferred cladding for this embodiment is an imidized acrylic based polymer. In this embodiment, the polymer optical waveguides demonstrate a use temperature of 120 0 C or above, The polymer optical waveguides of this invention r/ay be of any length, shape, or arrangement, known to mJne skilled in the art. The optical waveguides may be round, square, triangular, may be in the shape of a hollow light pipe wherein the core is a hollow light pipe and the clad surrounds the hollow light pipe core. In the hollow light pipe configura- T WJ"l^ 1 7 d r lu~ I i WO 88/10438 PCT/US88/02128 -13tion, the clad may surround the core and cover th inside of the core in the light pipe. The poly?.er optical waveguides may be arranged in a ribbon tape structure, or put together in an n by n array wherein n refers to an integer of 1 or greater.

The polymer optical waveguides .f this invention may be prepared by any proces's well known in the art for preparing optical fibers In one embodiment, the core and clad may be formed into a preform which is thereafter heated to a temperature at which the polymers may be redrawn, then the preform is drawn down to an appropriate size for the polymer optical waveguide. In another embodiment, a fiber of the core may be extruded, and then the cladding may be coated on the core fiber and thereafter cured in place. The use of cup coating techniques may generally be utied in this approach, and any curing mechanism which adequately cures the cladding onto the core is suitable, for example, heat cure or ultraviolet cure.

In another method, the optical fiber may be formed by a co-extrusion process wherein the core and the cladding are conLurrentAy extruded to form the desired shape. In a co-exctrusion process, the core material and cladding material are separately heated to a suitable temperature for extrusion, thereafter the polymers are extruded. The core material is fed into a pre-extrusion cylinder and simultaneously, the cladding material is fed into that cylinder about the outside of the core material, the materials are then passed through an orifice in a spinnerette into an air region wherein the fiber is cooled and drawn down to the Sdesired fiber size. The extrusion temperature is dependent upon the particular core and cladding used '-rr i WO 88/10438 PCT/US88/02128 -14and the temperature used must be suitable for both components. One skilled in the art would be able to determine such temperatures based upon the teachings contained herein. Generally for the aromatic ester carbonates as the molecular weight and the est;er content go up the extrusion temperatures which give the best optical waveguides also go up. The temperature at which the core and the clad are heated before extrusion are not necessarily the same. The temperature at which the fiber is extruded is not necessarily the same as the temperature at which the core or the clad is preheated. One skilled in the art would be able to determine such temperatures based upon the teachings contained herein. In those embodiments where the cladding is an imidized acrylic polymer, an aromatic ester carbonate, a blend of an aromatic ester carbonate with a bisphenol based polycarbonate or syndiotactic polymethylmethacrylate, the temperature at which the fiber is co-extruded may be higher than the temperature at which a fiber is extruded wherein the cladding comprises other acrylics or a fluoropolymer. In processing, the core material and the cladding material are pre-heated separately to temperatures at which the polymers have a viscosity which is suitable for coextrusion. The temperatures of each pre-heating zone may be different. The cladding and core material are extruded at the .s ne temperature, said temperature chosen to be compatible for the extrusion of both materials. Such extrusion temperatures are readily known, or ascertainable, by one skilled in the art.

Preferably, the core material is pre-heated to a temperature of between 400°F (2050C) to 545 0 F (285°C).

In the embodiment wherein the core material is an aromatic ester carbonate or a blend of an aromatic .1 WO 88/10438 PCT/US88/02128 ester carbonate and a polycarbonate wherein the total mole. jpertr, amount;of ester linkages in the core is between percent and 95 percent, with the remaining linkages being carbonate linkages, the more preferred temperatures to which the corei material is pre-heated is between 480 and 520°F (249 0 C to 271C), even more preferably between 480 and 500°F (249°C to 260°C). In the embodiment wherein the core which comprises an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total mole- iecent aouArctof ester linkages in the core is between percent and 50 percent, with the remaining linkages being carbonate linkages, the more preferred temperatures to which the core material is pre-heated is between 400 and 500 0 F (205°C to 260 0 even more preferably between 430 and 470 0 F (221'C to 243 0

C).

Wherein tihe cladding is an acrylic or a fluoropolymer the temperature to which the cladding material may be pre-heated is preferably between 410 and 510F (210°C to 266 0 more preferably between 420 and 470 F (216°C to 244°C), and most preferably between 430 and 450'F (221°C to 2330C). In that embodiment wherein the cladding is imidized acrylic material, an aromatic ester carbonate, or a blend of an aromatic ester carbonate with\ a polycarbonate, the preferred preheat temperatui're is between 420 and 510 F (216°C to 2660C), even more preferahly between 430 and 500 0 F (221°C to 2600C), and most preferably between 440 0 F and 490°F (227°C to 255°C).

The temperature of the spinnerette at the point of extrusion is preferably between 410 and 540°F (210°C to 2830C). In the embodiment wherein the core material is an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total m te ce is b n nmoun-)j of ester linkages in the core is between I I C~ 1-L- i WO 88/10438 PCT/US88/02128 -16percent and 95 percent, with the remaining linkages being carbonate linkages, and the cladding is imidized acrylic material, an aromatic ester carbonate, or a blend of an aromatic ester carbonate with a polycarbonate or syndiotactic polymethylmethacrylate, more preferred spinnerette temperatures are between 460 0 F (2380C) and 540°F (283°C), even more preferably between 470°F (244°C) and 520°F (271 0 and most preferably between 480'F (2490C) and 510°F (266°C). In 1 the embodiment wherein the core comprises an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total amount of ester linkages in the core is between 0.5 percent and 50 percent, and the cladding is an acrylic or a fluoropolymer, preferred spinnerette temperatures are between 410 F (210°C) and 480°F (249°C), more preferably between 420°F (216°C) and 460 F (2380C), and most preferably between 430°F (221°C) and 450°F (233°C). The preferred draw down ratio during formation of the optical fiber is between 5 and 75, more preferably between 10 and 50, and most preferably between 10 and Draw down ratio as used herein means the ratio of the cross sectional area of the spinnerette orifice to the cross sectional area of the drawn fiber.

It is important during a co-extrusion process to match the viscosity of the polymers. Generally, the viscosity of the polymers under extrusion conditions 3 should be within a range of between 10,000 (1,000 Pas) and 500,000 poise (50,000 Pa-s), more preferably between 20,000 (2,000 Pats) and 200,000 poise (20,000 Pa-s) and most preferably between 50,000 (5,000 Pa-s) and 100,000 poise (10,000 Pa*s). Preferably, the difference in viscosity is less than 50,000 poise I- WO 88/10438 PCT/US88/02128 -17- (5,000 Pa-s), more preferably 25,000 poise (2,500 Pa-s), with the core material having the higher viscosity. The optical fibers of this invention preferably have an attenuation of 8 or less dB per meter at 820 nanometers, more preferably less than 4 dB per meter and most preferably less than 3 dB per meter.

The following examples are included for illustrative purposes only. As used herein, all parts and percentages are by weight unless specified otherwise.

Example 1 Preparation of Polymer Optical Waveguide of Aromatic Ester Carbonate and Imidized Acrylic Based Polymer Clad An aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent wherein the ratio of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four, was loaded into the core side of a dual ram extruder and heated to 490 F (255 0 The transfer line to the spinnerette was held at 540°F (283°C). The clad side of the dual ram extruder was charged with imidized acrylic based polymer, more particularly an organic amine treated acrylic available from Rohm and Haas under the designation XHTA-170N and heated to 470°F (244°C) and transferred at 470°F (24 4 The spinnerette temperature was about 490°F (255 0 An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 millimeters) with a core pressure of 1500 psi (10,342 kPa) and a clad pressure of 500 psi (3,447 kPa). The fiber was spun into an air zone of ambient temperature, and drawn down by the use of a pinch wheel puller. The draw down ratio was about 25. The fiber diameter of WO 88/1,0438 PCT/US88/02128 -18the finished fiber was 0.75 mm, with a cladding thickness of 0.011 mm. The fiber take up during the process was 2.2 meters per minute.

The optical fibers described were tested for various properties. One such test is for fiber attenuation. Fiber attenuation is measured via the cut back technique, an experimental apparatus as described in Figure 1 comprising a helium neon laser 1 from which light is passed through a spacial filter 2 into a fiber coupler 3 coupling the light source with the fiber 4 with the other end of the fiber connected to a light detector 5. The optical power transmission in a given length of fiber is measured. An amount of fiber is then removed from the length and the power transmission is again measured. The optical loss of that cut back is given by the following equation.

Loss log of P2 log of P1 x 10 db per meter length in meters The length used in the equation is the length of the fiber cut off of the fiber tested. The cut back is repeated several times and an average is taken.

The fibers were further measured for catastrophic loss temperature by the following procedure. A sample of plastic optical fiber four meters long is placed in chucks and both ends polished. The sample is loosely coiled and placed in an oven such that two meters are in the heated area and one meter on each end connects out to a light source and a photo detector, respectively. The output of the photo detector is WO 88/10438 PCT/US88/02128 -19displayed on a stripchart recorder. The source intensity and photo detector intensity are adjusted so as to give a nominal full deflection on the recorder under ambient conditions, The oven temperature is then increased at a rate of 1 or 2 0 °C per minute. The intensity of light transmitted through the fiber as a function of the instantaneous temperatures plotted.

Experimental results show for a variety of polymer optical fibers that the intensity of transmitted light remains relatively constant as the temperature is increased until a catastrophic loss temperature is reached where transmission decreases dramatically. The temperature is characteristic for a particular composition and a rapid method for the estimation of the polymer optical fibers ultimate use temperature.

A third test performed on these polymers was a water boil resistance. This method gives a rapid estimation of the polymer optical fiber's ability to resist moisture and humidity. The experimental procedure is the same as for the catastrophic loss measurement with the exception that the fiber is placed in a boiling water bath. The ability of the optical fiber to transmit light is measured over time while it is exposed. This sample is three meters long with one meter being immersed The time period for the transmitted light intensity to be reduced to 80 percent of the original value is recorded.

The ultimate tensile strength, ultimate yield strength, and break elongation of each fiber were tested by the following technique. A four inch (10 cm) length of fiber is stretched in an Instron tensile testing device at the rate of 0.2 inches (0.5 cm) per minute. Figure 2 gives a typical Instron recording of WO 88/10438.

PCT/US88/02128 stress versus strain. The fiber tension at point 6, see Figure 2, the point at which the fiber first yields,is the yield tensile strength. The tension at point 7, the point at which the fiber breaks, is the ultimate tensile strength. The total strain to break divided by the initial fiber length is the break elongation. The results of the testing are compiled in the table.

Example 2 Polymer Optical Waveguide With Aromatic Ester Carbonate Core and Cladding of Aromatic Ester Carbonate Blended With Bisphenol A Polycarbonate An aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent, wherein the ratio of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four, was loaded into the core side of a dual ram extruder and heated to 500°F (260 0 The transfer line to th" spinnerette was held at 500°F (260°C). The clad side of the dual ram extruder was charged with a blend of an aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent 2 and a bisphenol A polycarbonate to give a total ester linkage mole percentage of 25, and heated to 480'F (249°C) and transferred at 480°F (249°C). The spinnerette temperature was about 500F (260°C). An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 millimeters) with a core pressure of 1150 psi (7929 kPa) and the clad pressure was 400 psi (2758 kPa). The fiber was spun into an air zone of ambient temperature, and drawn down by the use of a pinch wheel puller. The draw down ratio was 25. The fiber diameter of the finished fiber is 0.75 mm, with a WO 88/10438 PCT/US88/02128 -21cladding thickness of 0.009 mm. The fiber take-up during the process was 2.9 meters per minute The fibers were tested in the same manner as described in Example 1 and the results of the testing are compiled in the table.

Example 3 Polymer Optical Waveguide With Aromatic Ester Core and Blend of Aromatic Ester Carbonate and Polycarbonate Cladding An aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent wherein the ratio of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four, was loaded into the core side of a dual ram extruder and heated to 500°F (260 0 The transfer line to the spin,lerette was held at 540°F (283 0 The clad side of the dual ram extruder was charged with a blend of an aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent and a bisphenol A polycarboriate to give a total ester linkage mole percentage of 5, and heated to 450°F (233°C) and transferred at 460 0 B (2380C). The spinnerette temperature was about 510°F (266 0 An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 millimeters) with a core pressure of 1500 psi (10,342 kPa) and a clad pressure of 300 pounds (2068 kPa). The fiber was spun into an air zone of ambient temperature, and drawn down by the use of a pinch wheel puller. The draw down ratio was 25. The fiber diameter of the finished fiber is 0.75 mm, with a cladding thickness of 0.013 mm. The fiber take-up during the process was 2.1 meters per minute. The fibers were tested in the same LirtM#.

WO 88/10438 PCT/US88/02128 -22manner as described in Example 1 and the results of the testing are compiled in the table.

ExampIle 4- Polymer Optical Waveguide With Core of Aromatic Ester Carbonate Blended With Bisphenol A Polycarbonate and a Cladding of Polymethylmethacrylate A blend of an aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent wherein the ratic of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four with a bisphenol A polycarbonate to give a total ester linkage mole percentage of 5, was loaded into the core side of a dual ram extruder and heated to 450'F (233'C). The transfer line to the spinnerette was held at 490F (255'C). The clad side of the dual ram extruder was charged with a polymethylmethacrylate and heated to 4 40'F (227'C) and transferred at 460°F (238°C). T e spinnerette temperature was about 510F' (266°C). An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 milli-meters) with a core pressure of 1700 psi (11,721 kPa) and a clad pressure of 650 psi (4481 kPa). The fiber was spun into an air zone of ambient temperature, and drawn down by the use of a pinch wheel puller. The draw down ratio was about The fiber diameter of the finished fiber is 0.75 mm, with a cladding thickness of 0,012 mm. The fiber take up during the process was 0.6 meters per minute. The fibers were tested in the same manner as described in Example 1 and the results of the testing are compiled in the table.

WO 88/10438 PCT/US88/02128 -23- Example 5 Polymer Optical Waveguide With Aromatic Ester Carbonate Core and Cladding of Aromatic Ester Carbonate Blended With Bisphenol A Polycarbonate An aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 mole percent wherein the ratio of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four, was loaded into the core side of a dual ram extruder and heated to 450°F (233°C). The transfer line to the spinnerette was held at 490°F (254 0 The clad side of the dual ram extruder was charged with a blend of an aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content of 75 role percent with a bisphenol A polycarbonate to give a total ester linkage mole percentage of 5, and heated to 440°F (227°C) and transferrcs! at 450°F (233°C). The spinnerette temperature was about 4909F (255°C). An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 millimeters) with a core pressure of 1700 psi (11,721 kPa) and a clad pressure of 400 psi (2758 kPa).

The fiber was spun into an air zone of ambient temperature, and drawn down by the use of a pinch wheel puller. The draw down ratio was about 25. The fiber diameter of the finished fiber is 0.75 mm, with a cladding thickness of 0.018 mm. The fiber take-up 0 during the process was 1.3 meters per minute. The fibers were tested in the same manner as described in Example 1 and the results of the testing are compiled in the table. WO 88/10438 PCT/US88/02128 -24- Example 6 Polymer Optical Waveguide With Core of Aromatic Ester Carbonate and a Cladding of Syndiotaotic Polymethylmethacrylate An aromatic ester carbonate wherein the bisphenol portion is based on bisphenol A with an ester content 'of 75 mole percent wherein the ratio of terephthaloyl chloride to isophthaloyl chloride moieties in the backbone is four with a molecular weight of 32,000, was loaded into the core side of a dual ram extruder and heated to 420°F (216'C). The transfer line to the spinnerette was held at 440°F (227°C). The clad side of the dual ram extruder was charged with a syndiotactic polymethylmethacrylate and heated to 420 0 F (216°C) and transferred at 440°F (227°C).

The spinnerette temperature was about 430°F (221 0 An optical fiber was then melt spun through a 0.15 inch diameter die (3.81 millimeters) with a core pressure of 1500 psi (10,342 kPa) and a clad pressure of 1250 psi (8618 kPa). The fiber was spun into an air zone of ambient temperature, and drawn down by the ule of a pinch wheel puller. The draw down ratio was about The fiber diameter of the finished fiber is 0.75 mm, with a cladding thickness of 0.024 mm. The fiber takeup during the process was 2.7 meters per minute. The fibers were tested in the same manner as described in Example 1 and the results of the testing are compiled in the table.

3 0 t, ftm 00 00 Break Elongation 00 percent Catastro-phic Example Loss Exaple Temperature

*C-

Water Boil Resistance min Attenuation dB/m at 633 nm Attenuation dB/m zt 820nm Tensile, Strength/ psi (kPa) 18.7 14,000 (96,527 kPa) 9,500 465,500,kPa) 12,100 (84,805 kPa) 9,100 (62,742 kPa) Yield Strength/ psi~ (kPa) 10,300 (71,016 kPa) 8,700 (59,984 kPa) 10,300 (71,015 kPa) 9,000 (62,054 kPa) 5.6 6-4 00 00 00

Claims (12)

1. A polymer optical waveguide which comprises: a core comprising an aromatic este carbonate or a blend of an aromatic ester carbonate with a bisphenol based polycarbonate; and a clad of a polymer which'adheres to the core and has a lower refractive index than the aromatic ester carbonate or the blend of tl,e aromatic ester carbonate and the bisphenol based polycarbonate wherein said optical waveguide transmits light through the core.

2. The polymer optical waveguide of Claim 1 wherein the aromatic ester carbonate contains units which correspond to the formula 0 0 0 20II II (R-OCR 2 CO)x (R 1 CO)y- S WO 88/10438 PCT/US88/02128 -27- wherein R1 is the residue of a bisphenol moiety; R 2 is arylene; and z is a positive real number sucl tat the aromatic ester carbonate has a molecular of between 4,000 and 200,000; wherein the ratio of x to y is between 0.0025 and

3. The polymer optical waveguide of Claim 1 wherein the bisphenol based polycarbonate contains units which correspond to the formula R 3 R3 4 R3 R 3 t wherein R 3 at each occurrence is independently H, Cl, Br, or C 1 -C 4 alkyl; R is a direct bond, carbonyl, -SO 2 a C 1 -C 6 divalent hydrocarbon, a CI-C 6 divalent fluorocarbon radical, or inertly substituted Ci-C 6 divalent hydrocarbon radical; and i i WO 88/10438 PCT/US88/02128 -28- t is independently in each occurrence an integer of between 16 and 800.

4. The polymer optical waveguide of Claim 2 wherein the bisphenol units of the aromatic ester carbonate, R I correspond to the formula R3 R 3 0 .O R4 0 R3 R3 wherein R 3 is independently at each occurrence H, Cl, Br, or C 1 -C4 alkyl; and R 4 is independently at each occurrence a direct bond, carbonyl, -SO 2 a C1-C6 divalent hydrocarbon, a CI-C 6 divalent fluorocarbon radical, or an inertly substituted CI-C 6 divalent hydrocarbon radical.

The polymer optical waveguide of Claim 1 wherein the total a~ount.)of ester linkages in the core is between 0.5 percent and 95 percent, with the remaining linkages being carbonate linkages.

6. The polymer optical waveguide of Claim which comprises: a core of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a moIle perce>T polycarbonate wherein the total amunt of ester linkages in the core is between 50 percent and -V r y 29 percent, with the remaining linkages being carbonate linkages; and a clad of an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total mole percent of ester linkages in the clad is between 0.5 percent and percent, with the remaining linkages being carbonate linkages, or syndiotactic polymethylmethacrylate.

7. The polymer optical waveguide of Claim 6 wherein the use temperature of the waveguide is 140 0 C or above.

8. The polymer optical waveguide of Claim 5 wherein the core comprises an aromatic ester carbonate or a blend of an aromatic ester carbonate and a polycarbonate wherein the total mole percent of ester linkages in the core is between ?ercent and 50 percent, with the remaining linkages being carbonate linkages; and a clad which comprises an acrylic, an imidized acrylic based 0 polymer, or a fluoropolymer.

9. The polymer optical waveguide of Claim 8 wherein the use temperature is 120°C or above,

10. The polymer optical waveguide of Claim 8 or 9 wherein the clad comprises a polyalkylacrylate, a polyalkylalkacrylate, a fluorinated acrylic or a fluoroolefin.

11, A polymer optical waveguide as defined in Claim 1 and as substantially herein described with reference to any one of the Examples.

12. A process for the preparation of a polymer optical waveguide as defined in ulalm 1 which process is substantially herein described with S. reference to any one of the Examples. DATED this EIGHTH day of JUNE 1990 The Dow Chemical Company o S Patent Attorneys for the Applicant 'RUSON FERGUSON MRC/85491