Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-05-11
2001-08-28
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S261000, C526S328500, C526S335000, C526S341000, C526S344000, C526S346000, C546S272400, C548S259000, C548S260000
Reexamination Certificate
active
06281313
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a 2,2′-bis(6-benzotriazolylphenol) compound, an ultraviolet ray absorber consisting of the compound, and a copolymer and a polymer composition containing the compound.
BACKGROUND ART
Among a large number of UV absorbers, a benzotriazole-type UV absorber which is transparent to visible light is used most widely in terms of amounts and applications. However, conventional UV absorbers involve various problems to be solved. For example, the conventional benzotriazole-type UV absorbers have the following drawbacks.
(1) They are high in vapor pressures because of the low molecular weights. When a conventional UV absorber is blended with a resin and molded, it tends to volatilize, so that the yield is decreased or the contamination of mold or the pollution of working environment occurs. Further, the absorber bleeds out of the surface of molded article or coating film with the lapse of time to impair the appearance of the product. it is washed out by rain or water containing a detergent or the like in using environment, failing to impart UV absorption to products over a long period of time.
(2) The benzotriazole-type compound has inherently a property to react with a wide variety of metal ions(metal ion reactivity). For this reason, it easily forms chelate compounds with metal ions, so that color formation occurs, impairing an inherent transparency to visible light and losing properties as UV absorber.
Accordingly, in order to alleviate the defects indicated in (1) and (2) above, namely, volatility, elution, reactivity with metal ions and the like, a method has been usually employed in which a bulky substituent is introduced in the molecule of UV absorber, especially, in an adjacent carbon atom having a phenolic hydroxyl group.
However, the bulky substituent to be introduced in the method is usually a tert-butyl group, a tert-octyl group or a dimethylbenzyl group. The introduction of such a substituent incapable of UV absorption lowers the molecular absorption coefficient in proportion to increased molecular weight of the UV absorber, with the result that UV absorption per molecule is reduced.
Another method is known in which 2-hydroxyphenylbenzotriazole group is introduced as bulky group (Japanese Unexamined Publication No. 49-61,071, Japanese Examined Patent Publication No. 55-39,180 and the like).
Although the compounds disclosed in these documents exhibit improved properties concerning volatility, elution, etc., but the effects achieved are still unsatisfactory. Further, these documents does not teach the importance of metal ion resistance.
Japanese Unexamined Patent Publication No.60-38,411 discloses an approach in which polymerizable unsaturated group (CH
2
═C(R
a
)COO(R
b
)—) (wherein R
a
is a hydrogen atom or a methyl group, and R
b
is a linear or branched alkylene group having 2 to 10 carbon atoms) is introduced into the molecule of UV absorber to convert it into a copolymer and to improve the properties relating to volatility and elution.
However, the polymerizable UV absorber described in the document has a defect that it does not sufficiently absorb UV and has a high volatility itself, so that it is volatilized when the graft polymerization reaction is conducted, for example, in an extruder or a kneading molding machine.
Accordingly, a UV absorber has not been found yet which can eliminate the defects associated with the, conventional UV absorber, namely, which is free from volatility and elution problems during polymerization or molding, which is excellent in alkali resistance, heat resistance and metal ion resistance and which has a high absorptivity. Consequently, it is desired to provide UV absorbers having been improved in these properties.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide, by solving various problems associated with the prior art as discussed above, novel 2,2′-bis(6-benzotriazolylphenol) compounds which do not volatilize during high-temperature processing nor bleed out of the surface of a molded article, which have high weatherability and high heat resistance for a long period of time, which are not colored in an atmosphere where alkalis or metal ions are present, and which have a high molecular absorption coefficient and excellent UV absorptivity.
Another object of the present invention is to provide a UV absorber which eliminates the defects associated with the conventional UV absorbers, namely, which is free from volatilization and elution during polymerization or molding, which is excellent in alkali resistance, heat resistance and metal ion resistance and which has high UV absorptivity.
Still another object of the present invention is to provide a copolymer comprising the above-mentioned 2,2′-bis(6-benzotriazolylphenol) compound as a copolymerizable component.
Another object of the present invention is to provide a polymer composition comprising the above-mentioned copolymer containing the 2,2′-bis(6-benzotriazolylphenol) compound.
Other features of the present invention will be apparent from the following description.
The present invention provides a 2,2′-bis(6-benzotriazolylphenol) compound represented by the formula
wherein
A represents a single bond, a methylene group, —CH(CH
3
)—, —C(CH
3
)
2
— or —C(CH
3
)(C
2
H
5
)—,
R
1
and R
5
are the same or different, and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, an alkoxy group having 1 to 4 carbon atoms or a halogen atom,
R
2
represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms,
R
3
represents a single bond or a linear or branched alkylene group having 1 to 6 carbon atoms, and
R
4
represents a hydrogen atom or a methyl group.
The 2,2′-bis(6-benzotriazolylphenol) compound of formula (1) is a novel compound which has not been disclosed in literature.
The 2,2′-bis(6-benzotriazolylphenol) compound of the present invention having a high molecular absorption coefficient is excellent in UV absorption markedly low in vapor pressure, high in heat stability, and excellent in alkali resistance and metal ion resistance. Accordingly, it is useful as a UV absorber.
In the compound of the present invention, a molecule of ultraviolet-absorbable group is introduced into a carbon atom adjacent a carbon atom having a substituent phenolic hydroxyl group. This compound does not form chelate compound nor is colored even in environment where alkali metal ions, alkaline earth metal ions such as calcium or the like, or metal ions such as iron, copper or the like are present.
Further, the substituent on the carbon atom adjacent the carbon atom having the phenolic hydroxyl substituent group in the compound of the present invention is not a mere bulky substituent such as a tert-butyl group, a tert-octyl group, a dimethylbenzyl group or the like, but an ultraviolet-absorbable group per se. Accordingly, the compound of the invention has a high molecular absorption coefficient, providing a highly excellent UV absorptivity.
The present invention provides a UV absorber comprising the above-mentioned 2,2′-bis(6-benzotriazolylphenol) compound of formula (1).
The 2,2′-bis(6-benzotriazolylphenol) compound of formula (1) of the present invention has a feature that it has a highly reactive addition-polymerizable group in the molecule. As a result, the compound of the present invention can be homopolymerized or copolymerized with an addition-polymerizable monomer to introduce the ultraviolet-absorbable groups into the side chains of the resulting polymer at a desired ratio.
The present invention provides a copolymer comprising a 2,2′-bis(6-benzotriazolylphenol) compound of formula (1) as a copolymerizable component in an amount of 0.01 to 70% by weight and having a weight average molecular weight of 2,000 to 1,000,000.
The present invention provides a copolymer comprising a 2,2′-bis(6-benzotriazolylphenol) compound of formula (1) and a vinyl monomer, the amount of 2,2′-bis(6-benzotriazolylphenol) compound as the c
Akada Mitsuo
Daimon Emiko
Nakano Shinji
Yamamoto Minoru
Baker & Botts L.L.P.
Otsuka Chemical Co. Ltd.
Pezzuto Helen L.
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