Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/3467—Heterocyclic compounds having nitrogen in the ring having more than two nitrogen atoms in the ring
  • C08K5/3472—Five-membered rings
  • C08K5/3475—Five-membered rings condensed with carbocyclic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients

Definitions

• This invention relates to aromatic resins and more particularly to a process for rendering aromatic resins resistant to discoloration by surface treatment with a synergistic stabilizer combination of an antioxidant and an ultraviolet light, absorber.
• Aromatic polymers such as bisphenol-A polycarbonates, polystyrene, ABS and the like are particularly subject to degradation by exposure to ultraviolet light. Not generally known, however, is the fact that these resins are also subject to discoloration by photooxidation. Thus, the incorporation of both an antioxidant and an ultraviolet light absorber would be beneficial in inhibiting discoloration of these resins.
• the combination is found to be synergistic when the resin is given a surface treatment of the combination in a suitable solvent.
• a solvent in which the resin is only partly soluble whereby it can diffuse into the surface of the resin without substantially degrading it enables one to use far less stabilizer than would be required if directly incorporated into the resin precursors as there is no substantial amount bound into the center of the resin and consequently unavailable for protecting the resin.
• by treating the surface of the resin in accordance with the invention there is no degradation or impairment of the desirable resin properties caused by incorporation of the stabilizers. While surface treatment of aromatic resins with protective ultraviolet light stabilizers has previously been accomplished, to applicant's knowledge it has not been previously suggested to combine an antioxidant and an ultraviolet light absorber to coat an aromatic resin and it is the provision of such a system to which this invention is directed.
• Aromatic resins which can be employed in the invention are those which are normally degraded by exposure to ultraviolet light.
• Typical resins include polycarbonate resins prepared by reacting a dihydric phenol such as bisphenol-A (BPA) with a carbonate precursor such as phosgene which are disclosed in U.S. Patent No. 3,309,220.
• BPA bisphenol-A
• phosgene phosgene which are disclosed in U.S. Patent No. 3,309,220.
• These polycarbonate resins which may be formed from mononuclear or polynuclear aromatic compounds can also be formed from halo substituted dihydric phenols such as 1,1-dichloro2,2-bis(4-hydroxyphenyl)ethylene (BPC) .
• styrene polymers such as polystyrene and ABS
• polymers containing ether linkages such as poly(2,6-dimethylphenylene oxide)
• polymer blends such as formed of 20 to 99% by weight of a polyphenylene ether which can be substituted with alkyl groups of from 1 to 4 carbon atoms, e.g., poly(2,6-dimethylphenylene)oxide, and 1 to 80% of a styrene polymer such as polystyrene.
• the particular resin employed is not critical as the stabilizer combination is effective in protecting conventional aromatic resins.
• Any ultraviolet absorber can be used, such as, for example, benzophenone derivatives, such as 2-hydroxy-4-methoxy-benzophenone , 2,4-dihydroxy-benzophenone, 2,2'-dihydroxy-4-methoxy-benzo ⁇ henone , 2-hydroxy-4-n-octoxybenzophenone , 2,2' -dihydroxy-4,4'-dimethoxy-benzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone , benzotriazole derivatives, such as 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole, 2-(2'-hydroxy-5'-tert butylphenyl)-benzotriazole.
• benzophenone derivatives such as 2-hydroxy-4-methoxy-benzophenone , 2,4-dihydroxy-benzophenone, 2,2'-dihydroxy-4-methoxy-benzo ⁇ henone , 2-hydroxy-4-n-octoxybenzophenone , 2,
• Any antioxidant can be used, such as, for example,2, 6-di-tert-butyl-p-cresol , 2,2'-methylene bis(4-methyl-6-tert-butyl-phenol) , 4,4'-butylidene bis (6-tert-butyl-m-cresol) , 1,1,3-tris (2' -methyl-4'-hydroxy-5'-tert-butyl-phenyl) butane, 4,4'-methylene bis (2 , 6-di-tert-butyl ⁇ henol), octadecyl 3-(3' , 5 ' -di-tert-butyl-4'-hydroxy-phenyl)propionate, 2,6-di-(1-methylheptadecyl)p-cresol, 1,3,5-trimethyl-2,4,6-tris (3', 5'-di-tert-butyl-4'-hydroxybenzyl)benzene, tetrakis [methylene 3-(
• ultraviolet light absorber and antioxidant employed will depend upon the particular stabilizer, the resin,. and solvent employed but generally an absorber concentration in the solvent from about 0.5% to about 20% and an antioxidant from about 0.1% to about 5% by weight is sufficient.
• Solvents which can be employed are those which will not decompose either the stabilizers or the resin but which will diffuse into at least the surface of the polymer so as to deposit the stabilizers.
• Typical solvents include aromatic, chloroaromatic and chloroaliphatic solvents.
• the particular solvent will depend upon the resin but exemplary of suitable solvents are methylene chloride, chloroform, toluene, benzene, tetrahydrofuran, chlorobenzene , and dichlorobenzene.
• the solvent is employed in an amount sufficient to contain the stabilizers and provide a vehicle for submerging or coating the resin.
• an immersion time of no more than about 5 to 15 seconds is sufficient to impregnate the resin and the solvent can be easily evaporated at room temperature in a period of between about 1/2 hour and about 24 hours .
• Molded chips (2" x 2" x 1/8") of the copolycarbonate of BPC (85 pts) and BPA (15 pts) of the type described in Polish Patent 48,893 containing a mold stabilizer and formed by injection molding were dipped for 10 seconds in ethylene dichloride containing a stabilizer in the amount indicated (infra) and tested under accelerated weather conditions with a QUV cyclic ultraviolet weather tester (Q-Panel Co.) maintained on a 4 hr light/dark cycle at full humidity. After exposure, the weathered chips were assessed for discoloration by measuring their yellowness index, YI, according to ASTM method D1925.
• A' is 2(2'-hydroxy-5'-methylphenyl)benzotriazole
• B 2 is 2(2'-hydroxy-5'-tert-octylphenyl)benzotriazole
• C 3 is 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid triester of is 1,3,5-tris(2-hydroxyethyl-s-triazine-2,4,6-(1H,3H,5H)- trione
• D 4 is octadecyl 3-(3',5'-di-tert-butyl-4'-hydroxy-phenyl)propionate
• Molded stabilized chips (2" x 2" x 1/8") of Lexan polycarbonate containing 0.3% of 2(2' -hydroxy-5'-methylphenyl) benzotriazole as a bulk stabilizer plus a mold stabilizer were dipped for 10 seconds in ethylene dichloride containing stabilizer in the amount indicated (infra) and exposed to a 400 watt clear mercury lamp and rotated in an exposure chamber so as to maintain a surface temperature for the chips of 110oC.
• EDC is Ethylene Dichloride .
• UVS-1 is 2(2'-hydroxy-5'-methylphenyl)benzotriazole
• AO-1 is 3 , 5-di-tert-butyl-4-hydroxyhydrocinnamic acid triester of 1,3,5-tris (2-hydroxyethyl)s-triazine-2,4,6 1H, 3H, 5H) -trione
• AO-2 is tris (2', 5' - di-tert-butyl-4'-hydroxylbenzyl) isocyanurate
• AO-3 is 2 , 6-di-tert-butyl-4-tert-nonylphenyl

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Paints Or Removers (AREA)

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• 1979
  • 1979-10-29 WO PCT/US1979/000914 patent/WO1980000971A1/en unknown
  • 1979-10-29 JP JP50198079A patent/JPS55500905A/ja active Pending
• 1980
  • 1980-05-20 EP EP19790901564 patent/EP0020595A4/de not_active Withdrawn

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