Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-10-25
2004-02-24
Aulakh, Charanjit S. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C546S186000, C546S187000, C546S189000, C546S190000
Reexamination Certificate
active
06696570
ABSTRACT:
This invention relates generally to novel hindered amine light stabilizers (HALS) and their use as a protectant against ultraviolet radiation or light (“UV light”). Also included are concentrates and articles including such stabilizers, and methods of making all of the above.
BACKGROUND
It is well known that ultraviolet (“UV”) light or radiation, especially sunlight, can cause degradation of a variety of materials, especially polymeric materials. Often this results in embrittlement or yellowing of the materials, which may be in the form of molded articles, extruded articles, films, tapes, coatings, or the like. However, this degradation can be inhibited by the incorporation of light stabilizers in, or on, the polymeric articles. The most commonly used stabilizers are UV-absorbers, hindered amine light stabilizers (“HALS”), and phenolic and non-phenolic antioxidants.
HALS scavenge free radicals formed in polymeric material when the material is exposed to UV light. The functional component of the HALS molecule is typically the 2,2,6,6-tetraalkylpiperidine moiety. Typically, the 2,2,6,6-tetraalkylpiperidine moiety is anchored to a carbonyl or melamine functional group (See, e.g., U.S. Pat. Nos. 4,331,586; 3,840,494; Re. 31,342; Re. 30,385; 3,640,928; 4,086,204; 4,265,805). Anchoring the 2,2,6,6-tetraalkylpiperidine moiety to a carbonyl or melamine functional group typically lowers the volatility and extractability of a stabilizer. Low volatility is an important characteristic of light stabilizers in applications where high temperatures are encountered, which occurs frequently in the processing of thermoplastics and in the curing of thermoset resins and coatings. Often, high temperatures are also present in the end-use applications for the stabilized material. Low volatility helps prevent loss of the stabilizer during processing, curing, and high temperature end uses. Typically, HALS molecules containing the 2,2,6,6-tetraalkylpiperidine group anchored to a carbonyl group are made by reacting a 2,2,6,6-tetraalkylpiperidin-4-ol or 4-amino-2,2,6,6-tetramethylpiperidine with a carboxylic acid chloride or ester.
U.S. Pat. Nos. Re. 31,342, 4,021,432 and 4,049,647 disclose a class of 1- and 4-substituted piperidines that are stabilizers for organic materials. The stabilizers are produced by reacting the corresponding 1-substituted piperidinols with acid chlorides, or the corresponding 4-substituted piperidines, with a compound introducing a residue into the 1-position of the piperidine moiety.
U.S. Pat. No. 3,840,494 discloses a polymer composition stabilized against photo- and thermal deterioration by incorporating therein acid esters of 4-piperidinol derivatives in an amount sufficient to prevent such deterioration. The acid esters of the 4-piperidinol derivatives are prepared by reacting the 4-piperidinol derivative with a carboxylate ester in xylene with sodium hydroxide. For example, the reaction of 4-hydroxy-2,2,6,6-tetramethylpiperidine with ethyl benzoate produces 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.
Similarly, the 2,2,6,6-tetramethylpiperidin-4-ol can be reacted with diesters or diacid chlorides to produce diester-HALS. Also, the 2,2,6,6-tetramethylpiperidin-4-ol can be reacted with a diisocyanate to produce a diurethane-HALS. However, the relatively high cost of diisocyanates makes them less practical than diesters when preparing HALS.
Compounds which have an ester functionality at one terminus of a hydrocarbon chain and a urethane functionality at the other terminus of the hydrocarbon chain (alkoxycarbonylamino alkanoates) are known for various other uses other than light stabilization and can be prepared by a variety of synthetic schemes (See, e.g., Effenberger, F.; Drauz, K.; Foerster, S.; Mueller, W.,
Chem. Ber
., 114(1), 173-89; Dixit, A.; Tandel, S.; Rajappa, S.;
Tett. Lett
.; 35(33), 6133-4, Duong, et al.,
Aust. J. Chem
., 29, 2651-61, 1976; Iwaka et al.,
J. Org. Chem
., 31, 142-46, 1966; Taub; Hino;
J. Chem. Eng. Data
, 9, 106, 1964; U.S. Pat. No. 5,300,678 to Merger et al.).
U.S. Pat. No. 5,574,162 discloses 1-hydrocarbyloxy substituted HALS, which also contain reactive functional groups that chemically attach to selected polymer substrates by condensation reactions.
Oligomeric HALS are also known. For example, TINUVIN 622 is a commercially available oligomeric HALS produced by Ciba Specialty Chemicals Inc. of Hawthorne, N.Y. TINUVIN 622 can be produced by the reaction of dimethyl succinate with N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol. U.S. Pat. No. 4,233,412 discloses condensation and addition polymers wherein the recurrent molecular unit contains a polyalkylpiperidine radical that are useful as light stabilizers for plastics. In one embodiment the copolymer is formed by copolymerization or copolycondensation of polyalkylpiperidine containing monomers with polyalkylpiperidine free monomers such as caprolactam.
U.S. Pat. No. 6,271,377 discloses HALS which are substituted on the N-atom by N-alkyloxy moieties containing one to three hydroxyl groups.
U.S. Pat. No. 4,331,586 to Hardy discloses oligomers that contain at least one piperidyl moiety in the repeating unit for use as light stabilizers. While providing protection for polymeric materials, such as polypropylene, polymeric films containing the disclosed oligomeric HALS became brittle after exposure to UV light for about 1,700 hours.
HALS compounds may be used individually or in combination with other light stabilizers to inhibit photodegradation of polymers. For example, UV light absorbers, such as benzotriazoles and benzophenones, were initially used to stabilize polymeric materials and to prevent degradation of such materials from exposure to UV light. Later, it was discovered that HALS compounds were more effective than UV light absorbers alone, and thus, UV light absorbers are presently used in combination with at least one HALS compound in most conventional applications (See, e.g., U.S. Pat. Nos. 4,740,542; 4,619,956; 5,461,151; 5,721,298). Similarly, HALS compounds are often employed in combination with other stabilizers, such as antioxidants (See, e.g., U.S. Pat. No. 4,722,806). Combining the HALS with another stabilizer may provide a polymeric material with better resistance to weathering.
U.S. Pat. No. 4,619,956 discloses a method of stabilizing a polymer film, coating, or molded article against the action of light, moisture and oxygen by incorporating a HALS compound and a tris-aryl-s-triazine UV light absorber into a polymer. Preferably, the HALS compound is a 2,2,6,6-tetraalkylpiperidine compound, salt, or metal complex, and the UV light absorber is a tris-aryl-2-triazine of formula
where X, Y, and Z are each aromatic carbocyclic groups, and at least one of the aromatic groups has a hydroxy group ortho to the point of attachment to the triazine ring. Each of R
1
to R
9
is hydrogen, hydroxy, alkyl, alkoxy, sulfonic, carboxy, halo, haloalkyl, or acylamino. Each of the UV light absorbers and HALS compound are used in an amount of from about 0.01 to 5 percent by weight, but only formulations having equal amounts of UV light absorber and HALS compound are exemplified. The compositions are effective in stabilizing the polymeric material, which does not begin to lose gloss or turn yellow until after about 1,000 to 2,400 hours of exposure to UV light.
Thus, a need still remains for improved articles, and compositions and methods of use and preparation thereof, that stabilize polymeric materials and provide protection from exposure to UV light for extended periods of time. The present invention provides such compositions, articles and methods.
SUMMARY OF THE INVENTION
The invention provides a new class of oligomeric HALS having the formula:
T—&Parenopenst;E—F&Parenclosest;
i
—&Parenopenst;E—F′&Parenclosest;
j
—&Parenopenst;E′—F&Parenclosest;
k
—&Parenopenst;E′—F′&Parenclosest;
l
—S (II)
wherein i, j, k, and l are integers from about 0 to 300 and the sum of i, j, k, and l is greater than 2, wherein T is F, F′, or hydrogen; S is E, E′, or h
Gupta Ram. B.
Sassi Thomas P.
Aulakh Charanjit S.
Cytec Technology Corp.
Jubinsky James A.
Schultz Claire M.
Wasserman Fran
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