Claims
- 1. A process for the preparation of optical fibers and optical instruments by molding or extrusion of polymethyl methacrylate or of a methylmethacrylate copolymer containing up to 25% by weight of another C.sub.1 -C.sub.8 alkyl ester of (meth)acrylic acid having a transmittance greater than 92%, a haze less than 0.5% and a yellow index less than 2.5, the transmittance and haze being determined on 3 mm thick specimens according to A.S.T.M. D 1003-61 and, the yellow index on 60 mm thick specimens according to A.S.T.M. D1925-70, obtained by a process comprising:
- a. continuously feeding a polymerization reactor with a reaction mixture consisting essentially of methylmethacrylate or methylmethacrylate with another C.sub.1 -C.sub.8 alkyl(meth) acrylate, from 0.001 to 0.1% by weight of a polymerization radical starter, a molecular weight modifier, and from 5 to 30% by weight of a polymerization adjuvant selected from the group consisting of n-butylformate, n-butylacetate, isobutylacetate, tert.butylacetate, ethylpropionate, methylbutyrate, ethylbutyrate and methylhexanoate;
- b. partially converting the reaction mixture at about 120.degree. C. to 160.degree. C., and at a pressure ranging from the mixture vapor tension to 0.5 MPa; and
- c. devolatilizing the partially converted polymer at about 200.degree. C. to 250.degree. C.;
- wherein the viscosity of the reaction mixture is maintain in a range to avoid self-acceleration.
- 2. A process for the preparation of optical fibers and optical instruments comprising the steps of:
- (a) continuously feeding a polymerization reactor with a reaction mixture consisting essentially of methylmethacrylate or methylmethacrylate with up to 25% by weight of another C.sub.1 -C.sub.8 alkyl(meth) acrylate, from 0.001 to 0.1% by weight of a polymerization radical starter , a molecular weight modifier, and from 5 to 30% by weight of a polymerization adjuvant solvent selected from the group consisting of n-butylformate, n-butylacetate, isobutylacetate, tert.butyl-acetate, ethylpropionate, methylbutyrate, ethylbutyrate, and methylhexanoate;
- (b) partially converting about 70 to 90% of the reaction mixture at about 120.degree. C. to 160.degree. C., and at a pressure ranging from the mixture vapor tension to 0.5 MPa;
- (c) devolatilizing the partially converted polymer at about 200.degree. to 250.degree. C.;
- (d) sending the devolatilized polymer in a molten state to a molding device or an extruding device; and
- (e) making a molded or extruded product having a transmittance greater than 92%, a haze less than 0.5% and a yellow index less than 2.5, the transmittance and haze being determined on 3 mm thick specimens according to A.S.T.M. D 1003-61, and the yellow index being determined on 60 mm thick specimens according to A.S.T.M. D1925-70;
- wherein the viscosity of the reaction mixture is maintain in a range to avoid self-acceleration.
- 3. The process of claim 2, wherein the polymer devolatilization is carried out at a pressure from atmospheric pressure to 10.sup.3 pa.
- 4. The process of claim 2 wherein the molecular weight modifier is present in an amount ranging from 0.1 wt % to 1.0 wt %.
- 5. A process for the preparation of optical fibers and optical instruments by molding or extrusion of polymethyl methacrylate or of a methylmethacrylate copolymer containing up to 25% by weight of another C.sub.1 -C.sub.8 alkyl ester of (meth) acrylic acid having a transmittance greater than 92%, a haze less than 0.5% and a yellow index less than 2.5, the transmittance and haze being determined on 3 mm thick specimens according to A.S.T.M. D 1003-61 and, the yellow index on 60 mm thick specimens according to A.S.T.M. D1925-70, obtained by a process comprising:
- a. continuously feeding a polymerization reactor with a reaction mixture comprising methylmethacrylate or methylmethacrylate with another C.sub.1 -C.sub.8 alkyl(meth) acrylate, from 0.001 to 0.1% by weight of a polymerization radical starter which have a half-life at 130.degree. C. between 0.3 to 3 hours, a molecular weight modifier selected from the mono or difunctional mercaptans of formula R.sub.1 --(SH).sub.m, wherein R.sub.1 represents an alkyl radical, a cycloalkyl radical, a C.sub.1 -C.sub.20 aromatic radical and m is an integer from 1 to 2 or of formula (SH--R.sub.2 --COO).sub.n R.sub.3, where R.sub.2 and R.sub.3 represent a C.sub.1 -C.sub.10 alkyl radical and n is an integer ranging from 1 to 4 and from 5 to 30% by weight of a polymerization adjuvant selected from the group consisting of n-butylformate, n-butylacetate, isobutylacetate, tert.butyl-acetate, ethylpropionate, methylbutyrate, ethylbutyrate, and methylhexanoate;
- b. partially converting the reaction mixture at about 120.degree. C. to 160.degree. C., and at a pressure ranging from the mixture vapor tension to 0.5 MPa; and
- c. devolatilizing the partially converted polymer at about 200.degree. C. to 250.degree. C. and at a pressure ranging from atmospheric to 10.sup.3 Pa;
- wherein the viscosity of the reaction mixture is maintain in a range to avoid self-acceleration.
- 6. A process for the preparation of optical fibers and optical instruments comprising the steps of:
- (a) continuously feeding a polymerization reactor with a reaction mixture comprising methylmethacrylate or methylmethacrylate with up to 25% by weight of another C.sub.1 -C.sub.8 alkyl(meth)acrylate, from 0.001 to 0.1% by weight of a polymerization radical starter which have a half-life at 130.degree. C. between 0.3 to 3 hours, a molecular weight modifier selected from the mono or difunctional mercaptans of formula R.sub.1 --(SH).sub.m, wherein R.sub.1 represents an alkyl radical, a cycloalkyl radical, a C.sub.1 -C.sub.20 aromatic radical and m is an integer from 1 to 2 or of formula (SH--R.sub.2 --COO).sub.n R.sub.3, where R.sub.2 and R.sub.3 represent a C.sub.1 -C.sub.10 alkyl radical and n is an integer ranging from 1 to 4, and from 5 to 30% by weight of a polymerization adjuvant solvent selected from the group consisting of n-butylformate, n-butylacetate, isobutylacetate, tert.butylacetate, ethylpropionate, methylbutyrate, ethylbutyrate, and methylhexanoate;
- (b) partially converting about 70 to 90% of the reaction mixture at about 120.degree. C. to 160.degree. C., and at a pressure ranging from the mixture vapor tension to 0.5 MPa;
- (c) devolatilizing the partially converted polymer at about 200.degree. to 250.degree. C.;
- (d) sending the devolatilized polymer in a molten state to a molding device or an extruding device; and
- (e) making a molded or extruded product having a transmittance greater than 92%, a haze less than 0.5% and a yellow index less than 2.5, the transmittance and haze being determined on 3 mm thick specimens according to A.S.T.M. D1003-61, and the yellow index being determined on 60 mm thick specimens according to A.S.T.M. D1925-70;
- wherein during steps (a) to (c) the viscosity of the reaction mixture is maintained in a range to avoid self-acceleration.
- 7. The process of claim 6 wherein the pressure during step (c) is maintained at values ranging from atmospheric to 10.sup.3 Pa.
- 8. Optical fibers and optical instruments prepared for molding or extrusion of polymethylmethacrylate or of methylmethacrylate copolymer containing up to 25% by weight of C.sub.1 -C.sub.8 alkyl ester of (meth)acrylic acid, prepared according to the process describe in claim 1.
- 9. Optical fibers and optical instruments according to claim 8, having the following optical properties:
- Transmittance (ASTM D 1003-61); higher than 92% of 3 mm thick specimens;
- Haze (ASTM D 1003-61); lower than 0.5% on 3 mm thick specimens;
- Yellow index (ASTM D 1925-70); lower than 2.5 on 60 mm thick specimens.
Priority Claims (1)
Number |
Date |
Country |
Kind |
20378A090 |
May 1990 |
ITX |
|
Parent Case Info
This is a continuation of application Ser. No. 08/248,843, filed on May 25, 1994 now abandoned, which is a continuation of application Ser. No. 07/977,722, filed on Nov. 16, 1992 now abandoned, which is a continuation of application Ser. No. 07/701/904, filed on May 17, 1991, now abandoned.
US Referenced Citations (4)
Foreign Referenced Citations (4)
Number |
Date |
Country |
319622 |
Jun 1989 |
EPX |
2461164 |
Jun 1976 |
DEX |
55-007815 |
Feb 1980 |
JPX |
55-007845 |
Feb 1980 |
JPX |
Non-Patent Literature Citations (6)
Entry |
Hawley's Condensed Chemical Dictionary, 11th ed., 1987; p. 762; Van Nostrand Reinhold, New York. |
Principles of Polymerization Engineering, J.A. Biesenberger and D.H. Sebastian, Stevens Institute of Technology, A Wiley-Interscience Publication. |
The Condensed Chemical Dictionary, Ninth Edition, Von Nostrand Reinhold Company, pp. 288 and 360. |
Chem. Abstr. vol. 112, No. 6, Feb. 5, 1990 No. 36780z. |
James E. Mark and George Odian, ACS Short Course on Polymer Chemistry, p. 172 [American Chemical Society]. |
James L. Throne "Plastics Process Engineering" pp. 99, 1979. |
Continuations (3)
|
Number |
Date |
Country |
Parent |
248843 |
May 1994 |
|
Parent |
977722 |
Nov 1992 |
|
Parent |
701904 |
May 1991 |
|