Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-09-28
2001-11-06
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S312000, C526S321000, C526S323200, C526S286000, C528S375000, C528S376000
Reexamination Certificate
active
06313251
ABSTRACT:
The present invention relates to the manufacture of plastic optical articles such as video discs and ophthalmic lenses.
The most widely used plastic ophthalmic lens material is polymerised diethylene glycol bis (allyl carbonate). This polymer has proved a satisfactory material for the manufacture of ophthalmic lenses because of a combination of features, including excellent transmission, resistance to discolouration, high strength and high impact resistance. The material has a reasonable abrasion resistance and can be coated to improve that resistance.
Lenses formed from polymers including divinyl benzene are generally brittle and have a high yellowness index.
In Australian Patent Application 81216/87, the entire disclosure of which is incorporated herein by reference, applicant describes a cross-linkable casting composition including at least polyoxyalkylene glycol diacrylate or dimethacrylate and at least one polyfunctional unsaturated cross-linking agent. Whilst the lenses produced from the prior art compositions provide advances in the art, difficulties may be encountered in certain applications. For example, difficulties may be encountered in some patients in fitting lenses made from such compositions. Eye discomfort, including eye fatigue problems, may be encountered. Moreover, such lenses have been found to be cosmetically unattractive.
Further, in Australian Patent Application 75160/91, the entire disclosure of which is incorporated herein by reference, applicant describes a polyoxyalkylene glycol diacrylate or dimethacrylate; a monomer including a recurring unit derived from at least one radical-polymerisable bisphenol monomer capable of forming a homopolymer having a high refractive index of more than 1.55; and a urethane monomer having 2 to 6 terminal groups selected from a group comprising acrylic and methacrylic groups.
Japanese Patent Application 63-309509 to Showa Denko KK discloses the formation of a prepolymer of divinyl benzene and a polythiol compound which may be used in the formation of optical materials with high refractive indexes.
Japanese Patent Application 63-19498 to Mistubishi Gas discloses a high refractive index composition of divinyl benzene and a thiol compound. However optical lenses produced thereby exhibit unacceptable strain characteristics and cure times.
However, there remains a need in the prior art for optical articles of very high refractive indexes, high Abbe number, high rigidity, very low densities and excellent colour, that still retain excellent mechanical properties.
Accordingly, it is an object of the present invention to overcome, or at least alleviate, one or more of the difficulties related to the prior art.
Accordingly, the present invention provides a cross-linkable polymeric casting composition including an effective amount of
an acrylic or methacrylic monomer which provides high rigidity and low colour dispersion (High Abbe number) to the final product;
a di- or polythiol compound;
a di- or polyvinyl monomer; and optionally
a polymerisable comonomer.
The casting composition may be heat and/or UV-curable.
The optical article formed from the casting composition of the present invention may exhibit a refractive index in the high to very high-index range, high Abbe number, low density and high rigidity.
By the term “high refractive index”, as used herein, we mean a polymer having a refractive index of at least approximately 1.55, preferably 1.57. By the term “very high refractive index” as used herein, we mean a polymer having a refractive index of approximately 1.59 or above, preferably 1.60 or above.
By the term “low density”, as used herein, we mean a density in the range of approximately 1.15 to 1.25 g cm
−3
.
By the term “Abbe number”, as used herein, we mean the number expressing the extent to which the shorter and longer wavelengths of light are separated by refraction through a lens, that is the amount the lens disperses the various colours. The greater the number, the smaller the dispersion. The Abbe number may be calculated utilising the following formula:
ν
=
n
D
-
1
n
F
-
n
C
n=refractive index at the stated wavelengths below:
D=589.3 nm (sodium) yellow
F=486.1 nm blue green
C=656.3 nm red
By the term “high Abbe number” as used herein, we mean a polymer having an Abbe number of at least approximately 35, preferably 38 or above.
By the term “high rigidity” as used herein, we mean a polymer having a glass transition temperature (Tg) of at least approximately 65° C., preferably approximately 70° C., more preferably approximately 75° C. or above.
The acrylic or methacrylic monomer (Component A) may be selected from acrylates or methacrylate derivatives of a cycloolefin. An acrylate or methacrylate derivative of tricyclodecane is preferred.
The acrylate or methacrylate derivative may be of the formula:
where R can be H or CH
3
a=1-3, b=1-3, m=−0-6, n=0-6.
Sp is a spacer group selected from one or more of the following
wherein p=1-4
A tricyclodecane dimethanol diacrylate or methacrylate is preferred.
A tricyclodecane dimethanol diacrylate or diacryloyl oxymethyl tricyclodecane of the following formula is preferred.
The acrylic or methacrylic monomer (Component A) may be present in amounts sufficient to provide high Abbe number and high rigidity, but not so much as to cause brittleness or low tintability. Amounts of from approximately 10 to 60% by weight, preferably approximately 30 to 55% by weight, more preferably approximately 35 to 45% by weight, based on the total weight of the casting composition have been found to be suitable.
The di- or polythiol compound (Component B) may be of any suitable type. A di-, tri- or tetra polythiol compound may be used. A tri- or tetra-polythiol is preferred. The thiol may be selected from one or more of the following:
(a) 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol[MDO]
(b) Triemthylolpropane Tris(3-mercaptopropionate)[TTMP]
(c) Pentaerythritol Tetrakis (3-mercaptoacetate)[PTMA]
(d) Trimethylolpropane Tris(3-mercaptoacetate)[TTMA]
(e) 4-t-butyl-1,2-benzenedithiol
(f) Bis-(2-mercaptoethyl)sulfide HSCH
2
CH
2
SCH
2
CH
2
SH
(g) 4,4′-thiodibenzenethiol
(h) benzenedithiol
(i) Glycol Dimercaptoacetate
(j) Glycol Dimercaptopropionate Ethylene Bis(3-Mercaptopropionate)
(k) Polyethylene Glycol Dimercaptoacetates
(l) Polyethylene Glycol Di(3-Mercaptopropionates)
(m) Pentaerythritol Tetrakis (3-mercapto-propionate) [PTMP]
(n) Mercapto-methyl tetrahydrothiophene [MMTHT]
(o) Tris-(3-mercaptopropyl)isocyanurate [TMPIC]
(p) 2-mercaptoethyl sulphide
HSCH
2
CH
2
OCH
2
CH
2
SH
(q) 1,2,3-trimercaptopropane
(r) 2,2-bis(mercaptomethyl)-1,3-propanedithiol
C(CH
2
SH)
4
(s) Dipentaerythrithiol
O[C(CH
2
SH)
3
]
2
(t) 1,2,4-trimercaptomethyl benzene
(u) 2,5-dimercaptomethyl-1,4-dithiane
(v) BPHE-SH
(w) 4,8-bis(mercaptomethyl)-3,6,9-trithia-1,11-undecanedithiol
(x) 2-mercaptomethyl-2-methyl-1,3-propanedithiol
H
3
CC(CH
2
SH)
3
(y) DMDO: 1,8-dimercapto-3,6-dioxaoctane
HSCH
2
CH
2
OCH
2
CH
2
OCH
2
CH
2
SH
4-mercaptomethyl-3,6-dithia-1,8-octanedithiol [MDO] is particularly preferred.
(z) thioglycerol bismercaptoacteate (TGBMA) (3-mercapto-1,2-bismercaptoactatylpropane
The di- or polythiol compound (Component B) may preferably be present in amounts of from approximately 15 to 60% by weight, more preferably approximately 20 to 55% by weight and particularly about 25 to 45% by weight based on the total weight of the casting composition.
The inclusion of a divinyl or polyvinyl monomer (Component C) provides a reduction in flexibility, and thus an increase in hardness in optical articles produced therefrom.
The divinyl or polyvinyl monomer may be a rigid cyclic vinyl monomer. Component C may have the following formula:
wherein
X is selected from one or more of the following
Sp is a spacer group selected from one or more of the following
Y is hydrogen or halogen
n=0, 1 or 2
m=2-6
p=1-4
The divinyl or pol
Bateman Ian Roger
Cieslinski Bohdan Grzegorz
Diggins David Robert
Toh Huan Kiak
Asinovsky Olga
Nutter Nathan M.
Sola International Holdings Ltd.
LandOfFree
High index/high abbe number composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High index/high abbe number composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High index/high abbe number composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2610377