Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-05-16
2004-02-03
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C528S272000, C528S275000, C528S300000, C528S301000, C528S302000, C528S306000, C528S307000, C528S308000, C528S308600, C522S024000, C522S060000, C522S101000, C522S104000, C522S165000, C524S081000, C524S115000, C524S126000, C524S128000, C524S186000
Reexamination Certificate
active
06686401
ABSTRACT:
The present invention relates to a liquid composition polymerizable into organic glass.
More specifically, the present invention relates to a liquid composition which can be polymerized, by means of radicalic polymerization, into organic glass with a refractive index (n
D
20
)≧1.53, having good optical and physico-mechanical properties, and good dyeability, comprising the product obtained from the transesterification of a mixture of diallyl carbonate (A) and a phthalic ester (B), with one or more polyols (C), linear or branched, containing from two to eight carbon atoms in the molecule, a process for its preparation and its use in the preparation of organic glass.
A further object of the present invention relates to the organic glass obtained from the polymerization of said composition and the end-products obtained starting from said composition such as, for example, ophthalmic lenses and lenses for optical instruments.
Organic glass obtained from the polymerization of bis(allyl carbonate of diethylene glycol has been known and used for many years in this specific field. The use of the above organic glass, however, in the preparation of optical articles such as, for example, ophthalmic lenses, has various disadvantages mainly due to their relatively low refractive index (n
D
20
) in the order of 1.50.
As a result of this, especially in the case of high power ophthalmic lenses, these lenses have poorer aesthetic characteristics owing to the greater thickness and also lose the advantages of lightness due to the limited specific weight.
In order to overcome these drawbacks, compositions polymerizable into organic glass having a higher refractive index, have been prepared in the known art.
To achieve this objective, resort has been made to the introduction, in the above compositions, of reactive monomers or comonomers containing aromatic groups: among these, those consisting of allyl esters of aromatic carboxylic acids such as, for example, diallyl orthophthalate, diallyl isophthalate, diallyl terephthalate, triallyl trimellitate, etc., are of particular interest.
The introduction of the above species allows the refractive index (n
D
20
) to be increased up to values ranging from 1.53 to 1.57 and gives the optical articles produced good mechanical properties and thermal resistance.
Polymerizable compositions of the above type are described, for example, in European patent applications: EP 371,140, EP 392,514, EP 472,161 and EP 305,048.
Optionally, the diallylphthalate is added to the above compositions in the form of “diallylphthalate component” which consists of the product obtained from the reaction between diallyl phthalate and a glycol as described, for example, in the following European patent applications: EP 540,003 and EP 540,043.
In the above European patent applications, bis(allyl carbonate) of diethylene glycol is indicated as second component of the polymerizable compositions. These compositions are polymerized into organic glass having a refractive index (n
D
20
) equal to or higher than 1.53 using organic peroxides as polymerization initiators. The optic glass thus obtained has higher transparency characteristics, mechanical resistance to solvents, etc.
It has various disadvantages, however, linked to the fact that the components of the above polymerizable compositions have different reactivity and chemical characteristics. This makes it more difficult to control the polymerization reaction and results in the production of a polymeric end-product (for example, lenses) having a composition and properties which are not homogeneously distributed in the mass. This is demonstrated by the fact that the lenses obtained from the polymerization of said compositions, when observed in polarized light, have tensioned zones which can jeopardize their dimensional stability or create problems in the assembly phase of glasses.
The main problems, however, arise in the coloring operations of the above lenses, by immerging them in color baths using the known “dip dyeing” technique. In fact, the colored lenses thus obtained do not have uniform coloring due to the presence of areas with differing intensities. As color uniformity is one of the basic parameters which an optical article, such as an ophthalmic lens, must guarantee, the above problem is particularly serious.
The Applicant has now found that it is possible to overcome the above drawbacks of the known art by using a polymerizable liquid composition comprising mixed oligomers of allyl esters of aromatic carboxylic acids and aliphatic allyl carbonates, polymerized in the presence of organic polymerization initiators.
In particular, the Applicant has surprisingly found that the polymerizable liquid compositions object of the present invention, can be advantageously used for the preparation of organic glass having a refractive index (n
D
20
)≧1.53, an excellent combination of optical and physico-mechanical properties and good dyeability by immersion in color baths.
An object of the present invention therefore relates to a liquid composition polymerizable, by means of radicalic polymerization, into organic glass, comprising the product obtained from the transesterification of a mixture of diallyl carbonate (A) and a phthalic ester (B), with one or more polyols (C), linear or branched, containing from two to eight carbon atoms in the molecule.
In the liquid composition object of the present invention, the molar ratio (A+B)/C ranges from 2/1 to 7/1 and the molar concentration of (B) in the mixture (A+B) ranges from 10% to 70% with respect to the total of said mixture (A+B).
In the polymerizable liquid composition object of the present invention, the molar ratio (A+B)/C preferably ranges from 2.5/1 to 5/1 and the molar concentration of (B) in the mixture (A+B) ranges from 20% to 60% with respect to the total of said mixture (A+B).
Phthalic esters (B) which can be used for the purposes of the present invention, are ortho, meta or paraphthalates of aliphatic alcohols containing from 1 to 3 carbon atoms in the molecule.
Specific examples of phthalic esters (B) useful for the purposes of the present invention are: dimethyl orthophthalate, dimethyl isophthalate, dimethyl terephthalate, diethyl orthophthalate, diethyl isophthalate, diethyl terephthalate, dipropyl orthophthalate, dipropyl isophthalate, dipropyl terephthalate, diallyl orthophthalate, diallyl isophthalate, diallyl terephthalate, etc.
Preferred phthalic esters for the purposes of the present invention are: dimethyl isophthalate, dimethyl terephthalate, diallyl isophthalate and diallyl terephthalate.
When a phthalic ester different from diallyl orthophthalate, diallyl isophthalate or diallyl terephthalate is used as component (B), allyl alcohol (D) must be added to the reaction mixture in a molar quantity equal to about 1-3 times that of the phthalate (B) to ensure that the reaction product exclusively consists of species having chain-end allyl functionalities.
Polyols (C) which can be used for the purposes of the present invention are polyols consisting of linear or branched aliphatic glycols, containing from two to eight carbon atoms in the molecule.
Specific examples of glycols useful for the purposes of the present invention are: ethylene glycol, diethylene glycol, triethylene glycol, tetra-ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-propanediol, neopentylglycol, dipropyleneglycol, 2,2,4-trimethyl-1,3-pentanediol, etc.
Diethylene glycol is the preferred glycol for the purposes of the present invention.
Polyols (C) which can be used for the purposes of the present invention are also linear or branched aliphatic polyols containing from four to twenty carbon atoms and from three to six hydroxyl groups in the molecule.
Specific examples of polyols (C) containing from four to twenty carbon atoms and from three to six hydroxyl groups in the molecule useful for the purposes of the present invention are: pentaerythritol, trimethylolpropane, dipentaerythritol, ditrimethylolpropane, tris(hydroxyethyl)isocyanurate, etc.
Preferred polyols (C)
Bendandi Andrea
Forestieri Roberto
Renzi Fiorenzo
Acquah Samuel A.
Great Lakes Chemical (Europe) GmbH
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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