Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-07-27
2001-01-09
Szekely, Peter A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C526S286000, C523S106000, C558S251000, C560S222000
Reexamination Certificate
active
06172140
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.
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 poly functional 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.
However, there remains a need in the prior art for optical articles of high refractive indices, 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 di- or polythiol monomer of the formula
wherein
p is an integer of 0 or 1
M and M′ are each spacer groups selected from one or more of the following
wherein
m is an integer of 0 or 1 and n is an integer of 0 to 3,
R
1
, R
2
, R
3
and R
4
, which may be the same or different, are selected from hydrogen, alkyl or substituted alkyl of 1 to 10 carbon atoms, alkoxy or substituted alkoxy of 1 to 10 carbon atoms, or R
1
or R
2
is
and optionally
a polymerisable comonomer.
The casting composition may be heat and/or UV-curable, preferably UV curable.
A tri- or tetra- acrylic or methacrylic polythiol monomer is preferred.
The acrylic di- or poly-thiol monomer may be derived from a thiol selected from one or more of the following:
(a) 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol [MDO]
(b) Glycol Dimercaptoacetate
(c) Glycol Dimercaptopropionate Ethylene bis(3-Mercaptopropionate)
(d) 1,2,3-trimercaptopropane
(e)
2
-mercaptomethyl-2-methyl-1,3-propanedithiol
(f) 2,2-bis(mercaptomethyl)-1,3-propanedithiol
Preferably R
3
and R
4
are each hydrogen or methyl and one of R
1
and R
2
is
An illustrative example of an acrylic polythiol monomer is the trithiomethacrylate
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, 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 “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.
In a further aspect of the present invention, there is provided a method for preparing an acrylic or methacrylic di- or polythiol monomer of the formula
which method includes providing a di- or polythiol of the formula
wherein
M and M′ are each spacer groups as defined above,
p is an integer of 0 or 1,
R
5
and R
6
, which may be the same or different, are selected from hydrogen, alkyl or substituted alkyl of 1 to 10 carbon atoms, alkoxy or substituted alkoxy of 1 to 10 carbon atoms,
or R
5
or R
6
is
wherein R
3
is as defined above; and
reacting the di- or polythiol with an acrylic or methacrylic anhydride of the formula
wherein R
4
is selected from hydrogen, alkyl or substituted alkyl of 1 to 10 carbon atoms, alkoxy or substituted alkoxy of 1 to 10 carbon atoms.
Where the acrylic thio monomer is a tri thio acrylate, the method according to the present invention may further include
further reacting the di- or polythiol with an acrylic or methacrylic salt of the formula
wherein G is an alkali metal selected from sodium (Na) or potassium (K).
The further reaction steps may be undertaken simultaneously with, or subsequent to, the first reaction step.
It has been found that the method according to this aspect of the present invention may produce the acrylic thio monomers in high yield.
As stated above, the cross-linkable polymeric casting composition may optionally further include a polymerisable comonomer.
The polymerisable comonomer may be selected to improve the properties and/or processability of the cross-linkable polymeric casting composition. The polymerisable comonomer may be selected to improve tint rate, hardness, abrasion resistance and the like of the resulting polymer. The polymerisable comonomer may be an unsaturated, thiol or epoxy comonomer. The polymerisable comonomer may be selected from any suitable type, e.g. methacrylates, acrylates, vinyls, vinyl ethers, allyls, epoxides, thiols and the like.
The polymerisable comonomer may preferably be selected from one or more of epoxidised monomer or oligomer, di- or polythiol, di- or poly vinyls, allylics, polyoxyalkylene glycol di-, tri-, tetra- and higher acrylates or methacrylates, polymerisable bisphenol monomers, urethane monomers having 2 to 6 terminal acrylic or methacrylic groups, fluorene acrylates or methacrylates, and thioacrylate or thiomethacrylate monomers.
The polymerisable comonomer, when present, may be present in amounts of from approximately 30 to 90% by weight, preferably approximately 35 to 80% by weight, most preferably approximately 40% to 70% by weight, based on the total weight of the casting composition.
Where an epoxidised monomer or oligomer is included, the epoxidised monomer may function to improve curing and casting characteristics. The epoxidised monomer or oligomer may fall into one or more of the following classes: internal, terminal, mono-functional, di-functional, tri-functional, tetra-functional, aliphatic, aromatic, cyclic, structurally simple, structurally complex, esters, ethers, amines. An epoxidised soybean material may be used. The epoxidised monomer or oligomer may be selected from one or more of the following
Epoxidised soybean oil—Triglycerides of a mixture of epoxidised a) oleic acid, b) linoleic acid, c) linolinic acid
Propylene Oxide
Hexanediol diglycidyl ether (HDGE)
1,2 epoxy butane
Bisphenol fluorene diglycidyl ether (BPGE)
Epolight 100MF
AK-601
MY 721
The epoxidised monomer may be present in amounts of from approximately 0.001% to 10% by weight, preferably 0.01% to 5%, more preferably approximately 0.01% to 2%, based on the total weight of the casting composition.
Where a di- or polythiol comonomer is included, the di- or polythiol monomer may be of any suitable type. A di-, tri- or tetra polythiol compound may be used. A tri- or tetra-polythiol comonom
Chen Fang
Kok Chong Meng
Toh Huan Kiak
Burns Doane Swecker & Mathis L.L.P.
Sola International Holdings LTD
Szekely Peter A.
LandOfFree
Acrylic thio monomers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Acrylic thio monomers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Acrylic thio monomers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2464102