Plastic optical fiber and process for producing the same

• US 4,798,445 A
• Filed: 04/03/1986
• Issued: 01/17/1989
• Est. Priority Date: 05/17/1985
• Status: Expired due to Term

• Current Assignee: Mitsubishi Rayon Company Limited (Mitsubishi Chemical Holdings Corporation)
• Original Assignee: Mistubishi Rayon Co., Ltd.
• Inventors: Yamamoto, Takashi, Murata, Ryuji, Shimada, Katsuhiko, Terada, Hiromu, Tahara, Yasuteru, Sakunaga, Kenichi
• Primary Examiner(s): Lee, John D.
• Application Number:
  US06/847,515
• Time in Patent Office: 1,020 Days
• Field of Search: 264/1.1, 264/1.5, 264/174, 350/96.29, 350/96.30, 350/96.33, 350/96.34
• US Class Current: 385/143
• CPC Class Codes: B29C 48/00 Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor extrusion blow-moulding B29C49/04
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: C08L 69/00 Compositions of polycarbonates; Compositions of derivatives of polycarbonates
• CPC Class Codes: D01D 5/34 Core-skin structure; Spinnerette packs therefor
• CPC Class Codes: D01F 8/16 with at least one other macromolecular compound obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds as constituent
• CPC Class Codes: G02B 1/046 characterised by the core material
• CPC Class Codes: G02B 6/02033 Core or cladding made from organic material, e.g. polymeric material G02B1/04 takes precedence

Abstract

A plastic optical fiber which is superior in the light transmission characteristics, particularly in those within a visible light region and also superior in heat resistance, and a process for producing the same are provided, which plastic optical fiber comprises a polycarbonate as its core material and a polymer as its cladding material having a refractive index lower than that of the core material, wherein the relationship between the light transmission loss L₅₀₀ (dB/km) of the fiber as measured at a wavelength of 500 nm and that as measured at 660 nm being expressed by the following inequality:

L.sub.500 <L.sub.660 +4,000.

Claims

1. A plastic optical fiber comprising polycarbonate as its core material and a polymer, as its cladding material, having a refractive index lower than that of the core material, which is formed by a melt-spinning step, wherein said core material of polycarbonate is supplied to the melt-spinning step in the form of a powder which has not been heated to a temperature exceeding its crystalline melting point at any step other than the melt-spinning step, wherein the relationship between light transmission loss, L₅₀₀ (dB/km), of said fiber as measured at a wavelength of 500 nm and light transmission loss, L₆₆₀ (dB/km), of said fiber measured at a wavelength of 660 nm is expressed by the following relation (I):

space="preserve" listing-type="equation">L.sub.500 <

L.sub.660 +4,000 dB/km (I).

2. A plastic optical fiber according to claim 1, wherein said L₆₆₀ is 1,000 dB/km or less.

3. A plastic optical fiber according to claim 1, wherein said polycarbonate as the core material has an intrinsic viscosity of 0.3 to 0.6 dl/g as measured in methylene chloride at 20°

C.

4. A plastic optical fiber according to claim 1, wherein said polymer as the cladding material is a fluorine-containing polymer, and said fiber has outside the cladding, a protection layer composed of a polycarbonate having a heat deformation temperature of 100°

C. or higher.

5. A plastic optical fiber according to claim 1, wherein said polymer as the cladding material is a polymer having as its main component, at least one of the repetition units expressed by the following formula (II):

##STR6## wherein R represents an alkyl group of 1 to 5 carbon atoms, a fluorinated alkyl group of 1 to 5 carbon atoms or a cycloalkyl group of 3 to 6 carbon atoms.

6. A plastic optical fiber according to claim 5, wherein the melt flow rate [MFR]₁ of said core material and the melt flow rate [MFR]₂ of said cladding material have relationships expressed by the following inequalities [III] and [IV]:

space="preserve" listing-type="equation">3 g/10 min.≧

[MFR].sub.1 ≦

30 g/10 min. [III]

space="preserve" listing-type="equation">[MFR].sub.1 ≦

[MFR].sub.2 ≦

40 g/10 min. [IV]

7. A plastic optical fiber according to claim 1, wherein said fiber has outside the cladding, a protection layer composed of a polycarbonate having a heat deformation temperature of 125°

C. or higher.

8. A plastic optical fiber according to claim 7, wherein said fiber has outside the protection layer, a coating layer composed of a plastic having a silane-crosslinked structure.

9. A plastic optical fiber according to claim 8, wherein said silane-crosslinked structure is composed of --Si--O--Si--, and said plastic is composed of an organic polymer selected from the group consisting of polyethylene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylacrylate copolymer and tetrafluorinated ethylene-propylene copolymer.

10. A plastic optical fiber according to claim 1, wherein said fiber has outside the cladding, a protection layer composed of an organic polymer having a flexural modulus of 5,000 Kg/cm² or less.

11. A plastic optical fiber according to claim 10, wherein said fiber has outside the protection layer, a coating layer composed of a plastic having a silane-crosslinked structure.

12. A process for producing a plastic optical fiber by a melt-spinning step, wherein polycarbonate is used as the core material of the fiber and a polymer having a refractive index lower than that of the core material is used as the cladding material thereof;

wherein the core material of polycarbonate is supplied to the melt-spinning step in the form of a powder which has not been heated to a temperature exceeding its crystalline melting point at any preceding step other than the melt-spinning step, and then, melted at a temperature exceeding its crystalline melting point in the melt-spinning step.

13. The process of claim 12, wherein said polycarbonate is melted at a temperature exceeding its crystalline melting point in a melt-extruder and extruded from a spinning nozzle either (i) after cooling to a temperature between 200°

C. and the crystalline melting temperature of said polycarbonate or (ii) while cooling to a temperature between 200°

C. and the crystalline melting temperature of said polycarbonate.