2-Hydroxybenzophenone polymers

Cyasorb UV 2098. See 2-Hydroxy-4-acryloyloxyethoxy benzophenone Cyasorb UV 2126. See4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer... 

Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate stabilizer, light auto refinish coatings Benzophenone-12 stabilizer, light automotive prods. 4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer Benzophenone-12 3,5-Di-t-butyl-4-hydroxybenzoic acid, n-hexadecyl ester stabilizer, light cellulosics Drometrizole 2-(2 -Hydroxy-3,5 -di-t-amylphenyl) benzotriazole 2,4,4 -T ri hydroxybenzophenone stabilizer, light coatings Benzophenone-12 Drometrizole 2-(2 -Hydroxy-3,5 -di-t-amylphenyl) benzotriazole Methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate 1,2,2,6,6-Pentamethyl-4-... 

Benzophenone-12 stabilizer, light gel coats Bis (1,2,2,6,6-pentamethyl-4-piperidinyl) 2-(4-methoxybenzylidene) malonate stabilizer, light greenhouse 4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer stabilizer, light greenhouse covers... 

Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate stabilizer, light home siding 4-( 2-Acry I oyl oxyethoxy )-2-hydroxybenzophenone polymer stabilizer, light industrial coatings Benzophenone-12 stabilizer, light lacquers Drometrizole stabilizer, light LDPE Methacrylic acid copolymer stabilizer, light leather Benzophenone-4... 

UV absorber, automotive 4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer UV absorber, automotive coatings 2-(2 -Hydroxy-3,5 -di-t-amylphenyl) benzotriazoie... 

UV absorber, plasticizers Dipropylene glycol salicylate UV absorber, plastics 4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer Benzophenone-3 Benzophenone-6 Benzophenone-8 2-(2H-Benzotriazole-2-yl)-4-methyl-6-(3,4,5,6-... 

UV absorber, PMMA 2-[2-Hydroxy-3,5-d i-( 1,1 -di methyl benzyl) phenyl]-2H-benzotri azole UV absorber, polishes Phenyl salicylate UV absorber, polyamide 2-[2-Hy d roxy-3,5-d i -(1,1 -d i methyl benzyl) phenyl]-2H-benzotri azole UV absorber, polyester Benzophenone-3 Bis [2-hydroxy-5-methyl-3-(benzotriazol-2-yl) phenyl] methane UV absorber, polyester dyed fabrics Benzophenone-1 UV absorber, polyesters Benzophenone-2 Benzophenone-6 Bis [2-hydroxy-5-t-octyl-3-(benzotriazol-2-yl) phenyl] methane Bumetrizole 4-Dodecyloxy-2-hydroxybenzophenone Drometrizole Octrizole Phenyl salicylate 2,4,4 -Trihydroxybenzophenone UV absorber, polymers 4-(2-Acryloyloxyethoxy)-2-hydroxybenzophenone polymer Benzophenone-1 Dipropylene glycol salicylate Drometrizole 2,4,4 -T ri hydroxybenzophenone UV absorber, polymethyl methacrylate 2,4,4 -Tri hydroxybenzophenone UV absorber, polyolefins Bumetrizole 2-(3, 5 -Di-t-butyl-2 -hydroxyphenyl)-5-chlorobenzotriazole 2-(2 -Hydroxy-3,5 -di-t-amylphenyl) benzotriazole Nickel bis [0-ethyl (3,5-di-t-butyl-4-hydroxybenzyl)] phosphonate Nickel diisobutyidithiocarbamate UV absorber, polyvinyl butyral Octrizole UV absorber, PP... 

Acryloyloxyethoxy)-2-hydroxybenzophenone polymer C17H17CIO6 Griseofulvin C17H18CIN3O Bumetrizole C17H18N2O2... 

Additives used include plasticisers such as diphenyl diethyl ether, ultraviolet light absorbers such as 5-chloro-2-hydroxybenzophenone (1-2% on the polymer) and stabilisers such as phenoxy propylene oxide. 

UV absorbers have been found to be quite effective for stabilization of polymers and are very much in demand. They function by the absorption and harmless dissipation of the sunlight or UV-rich artificial radiation, which would have otherwise initiated degradation of a polymer material. Meyer and Geurhart reported, for the first time in 1945 [10], the use of UV absorber in a polymer. They found that the outdoor life of cellulose acetate film was greatly prolonged by adding phenyl salicylate (salol) [10]. After that, resorcinol monobenzoate, a much more effective absorber, was introduced in 1951 [11] for stabilization of PP, but salol continued to be the only important commercial stabilizer for several years. The 2,4-dihydroxybenzophenone was marketed in 1953, followed shortly by 2-hydroxy-4-methoxybenzophenone and other derivatives. Of the more commonly known UV absorbers, the 2-hydroxybenzophenones, 2-hy-droxy-phenyl-triazines, derivatives of phenol salicylates, its metal chelates, and hindered amine light stabilizers (HALS) are widely used in the polymer industry. 

The capability of 2-hydroxybenzophenone derivatives to dissipate light energy has been ascribed to rapid deactivation of the excited singlet state by intramolecular interaction between the carbonyl and hydroxyl groups, possibly involving reversible H-transfer. These proposals are outlined in Scheme I, where P and PP represent the polymer and photoproduct, respectively. 

Stabilizers belonging to this class absorb high energy radiation, and by a process of internal conversion provide a pathway for its harmless dissipation throughout the polymer system. Two of the commonly used types of UV absorber are 2-hydroxybenzophenones and 2-hydroxyphenylbenzotriazoles (B-75MI11500, B-79MIU505). 

Figure 6.15 Chemical structures of some polymer photostabilizers (a) 2-hydroxybenzophenone, (b) hydroxybenzotriazole, (c) oxanilide...

Four main types of antioxidants are commonly used in polypropylene stabilizer systems although many other types of chemical compounds have been suggested. These types include hindered phenolics, thiodi-propionate esters, aryl phosphites, and ultraviolet absorbers such as the hydroxybenzophenones and benzotriazoles. Other chemicals which have been reported include aromatic amines such as p-phenylenediamine, hydrocarbon borates, aminophenols, Zn and other metal dithiocarbamates, thiophosphates, and thiophosphites, mercaptals, chromium salt complexes, tin-sulfur compounds, triazoles, silicone polymers, carbon black, nickel phenolates, thiurams, oxamides, metal stearates, Cu, Zn, Cd, and Pb salts of benzimidazoles, succinic acid anhydride, and others. The polymeric phenolic phosphites described here are another type. 

Hydroxybenzophenones probably stabilize polymers by a screening mechanism rather than by energy transfer. 

Among the types of ultraviolet absorbers that may be used as stabilizers are salicylates, o-hydroxybenzophenones, o-hydroxyarylbenzotri-azoles, and certain acrylonitriles. The stabilization of polystyrene by other additives has also been reported. Matheson and Boyer (10) found that certain aliphatic amines and amino alcohols improved the light stability of the polymer. 

Several molecules which can undergo intramolecular proton transfer in the excited state have been found to be unusually photostable. Thus, for example, 2-hydroxybenzophenone is used as a photostabilizer in polymers while benzophenone itself is photoactive (Kysel, 1969). In crystalline 2-(2 -hydroxyphenyl)benzothiazole and its derivatives [3] a proton is transferred in the excited state from an... 

Some polymers show discoloration as well as reduction of the mechanical properties (e.g. aromatic polyesters, aromatic polyamides, polycarbonate, polyurethanes, poly (phenylene oxide, polysulphone), others show only a deterioration of the mechanical properties (polypropylene, cotton) or mainly yellowing (wool, poly(vinyl chloride)). This degradation may be less pronounced when an ultraviolet absorber is incorporated into the polymer. The role of the UV-absorbers (usually o-hydroxybenzophenones or o-hydroxyphenylbenzotriazoles) is to absorb the radiation in the 300-400 nm region and dissipate the energy in a manner harmless to the material to be protected. UV-protection of polymers can be well achieved by the use of additives (e.g. nickel chelates) that, by a transfer of excitation energy, are capable of quenching electronically excited states of impurities (e.g. carbonyl groups) present in the polymer (e.g. polypropylene). 

Light stabilisers also prevent photodegradation. UV absorbers such as hydroxybenzophenone or hydroxyphenyl triazole types, operate by absorbing and dissipating UV radiation prior to potential degradation of the polymer. No permanent chemical change occurs, so activity is retained. Hindered amine light stabilisers (HALS) are also used but their activity is not particularly well understood (80). 

Acrylic polymers are fairly insensitive to normal uv degradation since the primary uv absorption of acrylics occurs below the solar spectrum (59). The incorporation of absorbers, such as o-hydroxybenzophenone [117-99-7] further improves the uv stability (59). Under normal use conditions acrylic polymers have superior resistance to degradation and show remarkable retention of their original properties. 

Polymer supported 2-hydroxybenzophenones and 2-(2-hydroxyphenyl)-2ff-benzotriazoles have useful properties in articles used under high exposure of LTV U t, examples are transparent durable acrylic films, outdoor paints, transparent coatings for optical lenses, transparent protective layers of silver mirrors in solar concentrators or films used in encapsulation systems for photovoltaic modides in solar conversion devices [26, 54, 82, 92, 293]. Polymeric LS can also be used in cosmetics as sunscreening components of emulsions and ointments for protection of sensitive human skin against sunburn [324] or in medical aids, as nonleachable U V absorbing components of silicone rubber for vision aids (contact lenses) [99]. 

Arenes of the type ArX-Y, where X may be O, S, or NR, frequently undergo facile photoinduced homolytic cleavage of the X-Y bond with the Y radical subsequently attacking the aromatic ring. The photo-Fries reaction is the most common process of this type and has been reported within the year for aromatic esters which form part of a ptolymer chain or are pendant groups on a polymer chain. In the former case, the rearrangement of fluorene-based polyacrylates [for example, (292)] was studied. Formation of the o-hydroxybenzophenone moiety in the product (293) was monitored by u.v. and... 

---