Polymerizable thioacrylate compositions and optical lenses...

Details Polymerizable thioacrylate compositions and optical lenses... Polymerizable thioacrylate compositions and optical lenses...

2000-01-11

2003-10-21

Henderson, Christopher (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C351S159000

Reexamination Certificate

active

06635730

ABSTRACT:

A subject-matter of the invention is novel polymer compositions for the manufacture of optical lenses with a high refractive index and the optical lenses, in particular ophthalmic lenses, obtained from these compositions.
The term “optical lens with a high refractive index” means an optical lens with a refractive index of greater than or equal to 1.55 and preferably greater than 1.57.
The novel polymerizable compositions according to the invention are preferably of use in the manufacture of spectacle glasses.
An ophthalmic lens with a high refractive index must have all the following characteristics:
a high transparency (transmission generally of greater than 85% and preferably of greater than or equal to 90%), with an absence of or optionally a very low light scattering,
a high Abbe number of greater than or equal to 30 and preferably of greater than or equal to 35, in order to avoid chromatic aberrations,
a low yellowing index and an absence of yellowing over time,
a good impact strength (in particular according to the CEN and FDA standards),
a good suitability for various treatments (shock-proof primer, anti-reflective or hard coating deposition, and the like) and in particular good suitability for colouring,
a glass transition temperature value preferably of greater than or equal to 80° C. and better still of greater than 90° C., preferably of between 90 and 110° C.
In addition, the polymerizable compositions must also be easy to process industrially.
In particular, it is desirable for the compositions to be able to be photopolymerized, this being because this type of very fast polymerization makes it possible to reduce the cycle times for the manufacture of the lenses.
Another point to be taken into consideration is the number and the nature of the monomers used in the composition for the production of the organic glass.
These monomers must be readily available commercially, in large amounts, at low costs and with uniform quality.
On this latter point, monomers manufactured in industrial amounts exhibit substantially different characteristics, depending on the industrial manufacturing parameters, which can, to a certain extent, influence the properties of the final polymer and thus of the optical lens.
It is therefore desirable for the polymerizable composition to comprise a reduced number of precursor monomers. In addition, this limits the problems of storage and of logistics.
Polymerizable compositions for the production of polymers with a high refractive index are already known in the state of the art.
Patent Application EP 394,495 discloses polymerizable compositions based on 4,4′-bis-(methacryloylthio)diphenyl sulphide (denoted by BMTPS) and on another vinyl monomer copolymerizable with BMTPS and a polythiol represented by the general formula R(SH)
n
, in which R is a polyvalent organic group and n represents an integer equal to 2 or more.
Thus, Example 27 of this document describes a polymerizable composition with three constituents comprising, as parts by weight, 5 parts of BMTPS, 4 parts of a diethoxybisphenol A diacrylate and 1 part of an aromatic polythiol of formula:
The documents JP 61-23855, JP 61-23856 and JP 61-23858 disclose the production of spectacle glasses from compositions comprising 4 to 6 monomer constituents, including, in particular, BMTPS.
Furthermore, these compositions comprise aromatic vinyl derivatives which are not suited to photopolymerization.
Patent Application EP 609,454 relates to a process for the production of sulphur-comprising polymers with a high refractive index exhibiting a decreased colouring, a high transmission power, a resistance to yellowing (during ageing of the glass) and a low relative density.
The polymerizable compositions disclosed in this document comprise from 0.1 to 7% by weight of at least one compound chosen from chain-transfer agents and compounds for scavenging free radicals.
Mono- or polyfunctional mercapto compounds are mentioned among these compounds. It is specified, in this application, that, beyond 7% by weight, the mechanical properties of the polymer deteriorate or the excess compound escapes from the polymer.
Patent Application FR 95 006443, on behalf of the Company Essilor, discloses polymerizable compositions for the manufacture of polymers with a high index comprising bis(2-methacryloylthioethyl) sulphide (denoted by BMTES) or a BMTES/BMTPS mixture with a derivative of the polyethoxybisphenol A polymethacrylate type and an aromatic or cyclanic mono(meth)acrylate monomer.
In practice, the polymerizable compositions disclosed in this patent application comprise at least 4 to 6 polymerizable monomer constituents.
Furthermore, although the polymerizable compositions disclosed in this application are satisfactory, they can still be improved, in particular with regard to the yellowing index and the behaviour towards ageing.
An object of the invention is thus to provide simple polymerizable compositions with three base monomer consituents having improved properties with regard to the prior art.
According to the invention, the polymerizable composition comprises, as base copolymerizable monomer constituents, at least 85% by weight, with respect to the total weight of the copolymerizable monomers present in the composition:
of a mixture M consisting, per 100 parts by weight of the mixture, of:
(A) 20 to 80 parts of one or more nonaromatic compounds (I), preferably a single nonaromatic compound (I), comprising two thio(meth)acrylate functional groups
where R
4
=H or CH
3
, and
(B) 80 to 20 parts of a compound (II), or of a mixture of these compounds, of formula:
in which R
1
and R
2
represent, independently of one another, H or CH
3
and m+n has a mean value of 0 to 20 inclusive; and
3 to 30% by weight, with respect to the weight of the mixture M, of a polythiol, preferably 5 to 20%;
the composition comprising less than 5% by weight of other aromatic thio(meth)acrylate, aromatic or cyclanic mono(meth)acrylate and aromatic vinyl copolymerizable monomers.
The compositions according to the invention preferably comprise 90%, more preferably 95%, better still 98% and, as far as possible, 100% by weight of the base copolymerizable monomer constituents.
More preferably, the compositions according to the invention do not comprise di- and/or polyvinyl monomers. In the present application, the term “di- and polyvinyl monomers” is understood to mean monomers in which two or more CH
2
=CH— groups are bonded directly to hydrocarbonaceous fragments of the monomers, such as, for example, di- and polyvinyl hydrocarbons, divinylbenzene and divinylnaphthalene.
The polymerizable compositions according to the invention are preferably photopolymerizable compositions.
The nonaromatic compounds (I) comprising two thio(meth)acrylate functional groups of the mixture M of the polymerizable compositions according to the invention are compounds which are known in the art.
The compound (I) preferably corresponds to the formula:
in which R
3
represents a linear or branched divalent aliphatic hydrocarbonaceous radical which can optionally comprise, in its chain, one or more groups chosen from the divalent groups —O—, —S— or
preferably —O—or —S—, and better still the divalent group —S—, and R
4
represents H or CH
3
.
Mention may be made, among monomers of formula (I) recommended in the present invention, of:
S-2-acryloyloxyethyl thio(meth)acrylate,
S-2-methacryloyloxyethyl thio(meth)acrylate,
1,2-bis[(meth)acryloylthio]ethane,
1,2-bis[(meth)acryloylthio]propane,
1,3-bis[(meth)acryloylthio]propane,
1,4-bis[(meth)acryloylthio]butane,
bis[2-(meth)acryloylthioethyl] ether,
bis[2-(meth)acryloylthioethyl] sulphide (BMTES),
bis[2-(meth)acryloylthioethoxy]methane,
bis[2-(meth)acryloylthioethylthio]methane,
1,2-bis[2-(meth)acryloylthioethoxy]ethane,
1,2-bis[2-(meth)acryloylthioethylthio]ethane,
bis[2-(2-(meth)acryloylthioethoxy)ethyl] ether,
bis[2-(2-(meth)acryloylthioethylthio)ethyl]

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