GB2232667A - Ultraviolet light absorbing benzotriazolyl-benzophenone compounds and their copolymerizable derivatives - Google Patents

Abstract

New ultraviolet light absorbing compounds having benzotriazole and benzophenone moieties in a single molecule can be incorporated into a variety of organic materials and are effective in preventing photodegradation of polymers. Such compounds may be made by forming a benzophenone azo compound by the coupling reaction of diazonium salt of O- nitroanoline with 2,2',4,4'-tetrahydroxybenzophenone so that the coupling takes place mainly at the one of the 4'-positions of the 2,2',4,4'-tetrahydroxybenzophenone and triazolizing the resulting benzophene azo compound using zinc powder in an aqueous sodium hydroxide solution. The following compounds are claimed per se. <IMAGE> wherein R is H, halogen or alkoxy and R' is H, acryloyl, methacryloyl, allyl, alpha -acyloyloxy beta hydroxypropyl, or beta -hydroxyethyl.

Description

Ultraviolet Light Absorbing Compounds and their Copolymerizable Derivatives This invention relates to ultraviolet light (UV) absorbing compounds, their copolymerizable derivatives and to methods for making such compounds; and more particularly to ultraviolet light absorbing compounds of 5 (2H-benzotriazole-2-yl) 2,2',4,4'tetrahydroxy b enzophenone.

Polymeric materials are being increasingly used in a wide variety of applications. For example, there has been considerable growth in the use of plastic materials, particularly in construction and agricultural applications which involve outdoor use in relatively harsh environments. Products such as water proofing membranes, flooring materials, window frames, plastic pipes and greenhouse coverings are in particular demand for use in arid regions.

The absorption of radiation in the ultraviolet range by polymeric materials is a major cause of the light-induced degradation of such polymeric materials. Accordingly, it has become standard practice to add UV stabilizers to light sensitive polymers to absorb the harmful UV light or to quench the energy generated as a result of the excitation of the lightabsorbing functional groups in the polymer.

Such absorbers have been simply compounded with polymers prior to or during processing. However, the effectiveness of such absorbers in preventing photodegradation of polymers has in the past been limited by poor long-term performance. This poor long-term performance was due to the physical loss of absorbers from the polymer matrix through leaching out or through phase separation processes. Furthermore, the solubility of the absorbers in the polymer matrix was sometimes less than the minimum effective concentration, leading to absorber migration during processing or use which added to absorber loss.

Commercially available UV stabilizers have a number of limitations, for example, such stabilizers are generally designed for use in polymers which are subjected to relatively mild conditions. In other words, polymers including such stabilizers are not usually suitable for outdoor use in the harsh arid conditions such as those encountered in the Arabian Gulf countries and other parts of the world. Attempts to add UV stabilizers to a polymer in high doses, i.e., exceeding 2% increases incompatibility, phase separation and leaching from the polymer matrix which in turn results in less stability and increased cost. Thus, using a high concentration of UV stabilizer is not a practical solution to the problem of polymer stability under harsh weather conditions.

The prior art discloses information on the synthesis and application of polymerizable UV absorbers of phenyl benzotriazole and benzophenones. For example, Milionis et al. U.S.

Patent Nos. 3,072,585 and 3,159,646 disclose polymeric materials which have the property of selectively absorbing ultraviolet light. Milionis et al. disclose phenyl benzotrazole compounds that can be incorporated in resins or plastics like any other UV absorber to give good protection. Such compounds were also found to copolymerize with monomers for various plastics to become an integral part of the resin molecule. For example, copolymerization was carried out with monomers containing ethylenic double bonds, such as ethylene, propylene, butylene, styrene, methyl styrene, ethyl styrene, propyl styrene, acrylic acid and its amide, methlycrylic acid, acrylonitrile, vinyl esters such as vinylacetate and chloride, vinyl ethers such as vinyl butyrate, and such compounds.

Applicants have also disclosed the use of naphthylbenzotriazoles as UV absorbers and optical brighteners in their copending U.S. patent application entitled "Ultraviolet Light Absorbers with Fluorescent Brightening Characteristics" serial no. 07/254,842 filed Oct. 7, 1988. In addition, a Polymer Bulletin 12, 237-243 (1984) by Shanjun Li, Amitava Gupta, Ann Christine Albertson, Walter Bassett Jr. and Otto Vogl entitled "Functional Polymers" discloses Polymerizable Acrylic Ultraviolet Absorbers with two Benzotriazole Groups in the Molecules and extinction coefficients ranging from 3.0 to 3.5 x 104 L/mole/cm.

Applicants have now discovered a new class of polymerizable ultraviolet absorbers which are highly compatible with plastics in which they can be easily incorporated. The absorbers, according to the present invention, can be chemically bound to polymeric materials either by copolymerization techniques, grafting techniques or during processing of the polymer. Thus, the ultraviolet absorber becomes an integral part of the polymer chain.

Applicants have found that the UV absorbers, according to the present invention, do not have a tendency to leach out of the polymer matrix by exudation or volatilization during high temperature processing. In addition, these ultraviolet absorbers are not subject to solvent extraction or physical migration to the same degree as many of the commercially available absorbers. It has also been found that the polymerizable UV absorbers, according to the present invention, contain ethylenically groups and are suitable for incorporation into polymers by addition polymerization, grafting polymerization and cross-linking. Also, the polymerizable UV absorbers contain hydroxyethoxy groups and can be incorporated into polymers by condensation polymerization.We have also found that these UV absorbers are efficient monomers and homopolymers and as such provide good protection to the polymer matrix when they are incorporated therein.

In addition, the novel compositions disclosed herein are believed to have broader application, i.e., to a wider range of polymeric systems than many of the prior art compounds.

The novel compounds of our invention ccnprise the combination of the benzophenone and benzotriazole UV absorber molecules and their polymerizable derivatives of the following formula:

wherein R is hydrogen, alkoxy or halogen, and R1 is hydrogen, acryloyl, methacryloyl, allyl, -acryloyloxy- hydroxy propyl or B-hydroxyethyl. The above-defined polymerizable W absorbers may be copolymerized, grafted or cross-linked with vinyl monomers and polymers such as styrene, methyl styrene, acrylates, methacrylates, acrylamide acrylonitrile, methacrylonitrile, polyvinyl chloride, polyethylene, polypropylene, unsaturated polyesters, etc.High molecular weight homopolymers of the benzophenone-benzotriazole monomers, having an average molecular weight of about 3000 to 7000 and preferably about 4500, can also be prepared and incorporated into a variety of organic materials to impart W absorption properties.

The new benzophenone-benzotriazole conpounds, according to the present invention in which R is hydrogen, are W absorbers and may be prepared by the coupling reaction of a diazonium salt of o-nitroaniline and its chloro- and methoxy derivatives with 2,2', 4,4 -tetrahydroxybenzophenone in molar ratios of 1-1.5 to 1-2, respectively, at 0 to 5oC for 3 to 6 hours. The coupling takes place mainly at the 5-position of the tetrahydroxy benzophenone and the resulting monoazocompound may then be triazolized using zinc pownder in an aqueous sodium hydroxide solution at 20-30 C for 8 to 10 hours. The resulting W absorbing compounds have the following formula:

where R is hydrogen, alkoxy or halogen.

The new ultraviolet absorbers disclosed herein are 5(2H-Benzotriazole-2-yl) 2,2',4,4' tetrahydroxybenzophenone and its chloro and methoxy derivatives having four hydroxyl groups, three are sterically hindered as a result of hydrogen bonding to benzophenone as in 2 and 2'-positions and to the azo nitrogen group of the heterocyclic benzotriazole as in 4 position. The pendent hydroxyl group on the 4'-position can be utilized to introduce suitable polymerizable group.

Monomers, according to the present invention, may be prepared by the reaction of the 5(2H-Benzotriazole-2-yl) 2,2 ,4,4 - tetrahydroxybenzophenone and its chloro and methoxy derivatives with reactive monomers which are capable of free radical or condensation polymerization. Allyl bromide, acryloyl chloride, methacryloyl chloride, glycidyl acrylate, and ethylene chlorohydrin have been employed as polymerizable substrates.

The reaction of the 5(2H-benzotriazole-2-yl) 2,2',4,4'tetrahydroxybenzophenones with the above-mentioned compounds may be carried out by replacing the hydrogen on the 4'-position leaving the other hydroxyl groups at the 2,2' and 4-positions untouched. Suitably the molar ratios of the reactants are controlled to provide at least 1:1 molar ratio of the reactive monomers and the benzotriazole-benzophenone starting materials.

5(2H-benzotriazole-2-yl) benzophenones, according to preferred embodiments of the invention, are those where R is H and R' is acrylate, methacrylate or ss-hydroxyethoxy:

5(2H-benzotriazole-2-yl) 2,2', 4-trihydroxy4' -acryloxybenzoph enone

5(2H-benzotriazole-2-yl) 2,2', 4-trihydroxy-4'-methacryloxy benzophenone

5(2H-benzotriazole-2-yl) 2,2',Strihydroxy4'-ss-hydroxyethoxy benzoph enone These compounds can be copolymerized with commercially available monomers such as styrene, methylmethacrylate, acrylates, methylstyrene, acrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl halides, vinylidene halides, carbonates, ethylene, propylene, unsaturated polyesters and mixtures thereof in different ratios.The preparation of these compounds, their copolymerization and their UV absorption characteristics, are described in the following examples.

The following examples will more clearly illustrate the embodiments of the invention.

In these examples all parts are given by weight unless otherwise noted.

Example 1 Preparation of an ultraviolet absorbing compound according to a first embodiment of the invention, i.e., 5(2H-Benzotriazole-2-yl) 2,2' ,4,4'-tetrahydroxybenzophenone.

28.0 Parts of 2-nitroaniline was diazotized with 14.0 parts of sodium nitrite and 150 parts by volume of hydrochloric acid in 100 parts by volume of water. The solution of the diazonium salt was added to a mixture of 100.0 parts of 2,2',4,4'-tetrahydroxybenzophenone in 500 parts by volume of ethanol and 85.0 parts of sodium bicarbonate in 300 parts by volume of water at 5"C. The intermediate azo compound was isolated by filteration and dissolved in 300 parts by volume of 2N-sodium hydroxide and triazolized by the addition of 60 parts of zinc dust. The zinc was removed by filteration and the filterate acidified with concentrated hydrochloric acid. The solid product was then collected by filteration and recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 86%.

Example 2 Preparation of an ultraviolet absorbing compound according to a second embodiment of the invention, i e., 5(2H-5-methoxybenzotriazole-2-yl) 2,2' ,4,4'-tetrahydroxybenzophenone The procedure of Example 1 was followed using an equivalent quantity of 4-methoxy2-nitroaniline in place of the 2-nitroaniline. The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 79R: Example 3 Preparation of an ultraviolet absorbing compound according to a third embodiment of the invention, eye., 5(2H-5-chlorobenzotriazole-2-yl) 2,2' ,4,4'-tetrahydroxybenzophenone The procedure of Example 1 was followed using an equivalent quantity of 4-chloro-2nitroaniline in place of 2-nitroaniline.The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 78%.

Example 4 Preparation of polymerizable ultraviolet absorbing compound according to another embodiment of the invention i e., 5 (211-berizotriazol e-2-yl)2,2' ,44rihydroxy4'-acryloxybenzophenone.

3.0 parts of 5(2H-benzotriazole-2-yl) 2,2' ,4,4'-tetrahydroxybenzophenone were mixed with 0.7 parts of sodium hydroxide in 100 parts by volume of water. To this stirred mixture, 0.8 parts of acryloyl chloride in 40 parts by volume of chloroform were added dropwise.

The mixture was stirred at room temperature until the reaction was complete. The organic layer was isolated, dried and evaporated and the product was then recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 72%.

Example 5 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention i e., 5(2H-5-methoxybenzotriazole-2-yl)2 ,2' ,4-trihydroxyA'-acryloxybenzophenone. The procedure of Example 4 was followed using an equivalent quantity of 5(2H-5 methoxybenzotriazole-2-yl)2,2',4,4'-tetrahydroxybenzophenone in place of the 5(2H benzotriazole-2-yl)2,2',4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 73%.

Example 6 Preparation of a polymerizable ultraviolet absorbing compound according to a still further embodiment of the invention, i.e., 5(2H-5-chlorobenzotriazole-2-yl)2,2' ,4-trihydroxy-4'-acryloxybenzophenone.

The procedure of example 4 was followed using an equivalent quantity of 5(2H-5chlorobenzotriazole-2-yl)2,2'4,4'-tetrahydroxybenzophenone in place of the 5(2H benzotriazole-2-yl)2,2'4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 69%.

Example 7 Preparation of a polymerizable ultraviolet absorbing material according to another embodiment of the invention, i.e., 5(2H-benzotriazol e-2-yl)2 ,2' ,4-trihydroxy4'-methacryloxybenzophenone.

3.0 parts of 5(2H-benzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone were mixed with 0.8 parts of sodium hydroxide in 100 parts by volume of water. To this stirred mixture, 0.9 parts of methacryloyl chloride in 40 parts by volume of chloroform were added dropwise.

The mixture was stirred at room temperature until the reaction was complete. The organic layer was isolated, dried and evaporated. The crude product thus obtained was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 61%.

Example 8 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention; i.e., 5 (2H-5-methoxybenzotriazol e-2-yl)2,2' ,4-trihydroxy4'-methacryloxybenzophenone.

The procedure of Example 7 was followed using an equivalent quantity of 5(2H-5 methoxybenzotriazol e-2-yl)2,2' ,4,4' -tetrahydroxybenzophenone in place of the 5(2H benzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 59%.

Example 9 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention; i.e., 5(2H-5-chlorobenzotriazole-2-yl)2,2' ,4-trihydroxy4'-methacryloxybenzophenone The procedure of Example 7 was followed using an equivalent quantity of 5(2H-5 chlorobenzotriazole-2-yl)2 ,2' ,4,4'-tetrahydroxybenzophenone in place of 5(2H-benzotriazole 2-yl)2,2',4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from a mixture of ethanol and water to give yellowish needles with a yield of 60%.

Example 10 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention; i.e., 5(2H-benzotriazole-2-yl)2,2' ,4-trihydroxy-4'-allyloxybenzophenone To a stirred mixture of 3.0 parts 5(2H-benzotriazole-2-yl)2,2',4,4'- tetrahydroxybenzophenone and 0.8 parts potassium carbonate in 150 parts by volume of acetone were added 1.0 parts allyl bromide. The mixture was then heated at the reflux temperature with stirring until the reaction was complete. After 100 parts by volume of water had been added, the mixture was extracted with diethyl ether. The ether layer was then evaporated and the crude product thus obtained recrystallized from ethanol to give yellowish needles with a yield of 75%.

Example 11 Preparation of a polymerizable ultraviolet absorbing compound according to a further embodiment of the invention, i.e., 5(2H-5-methoxybenzotriazole-2-yl)2,2' ,4-trihydroxy-4'-allyloxybenzophenone The procedure of Example 10 was followed using an equivalent quantity of 5(2B-5- methoxybenzotriazole-2-yl)2,2',4,4'-tetrahydroxybenzophenone in place of 5(2H benzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give yellowish needles with a yield of 73%.

Example 12 Preparation of a polymerizable ultraviolet absorbing compound according to a further embodiment of the invention, i.e., 5(2H-5-chlorobenzotriazol e-2-yl)2 ,2' ,4-trihydroxy4'-allyloxybenzophenone The procedure of Example 10 was followed using an equivalent quantity of 5(2B-5- chlorobenzotriazol e-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone in place of 5 (2H-benzotriazole 2-yl)2, 2', 4 ,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give yellowish needles with a yield of 73%.

Example 13 The preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention, i.e., 5 (2H-5-b enzotriazol e-2-yl)2 ,2' , 4-trihyd roxy-4' (3-acryloxy-2-hydroxypropoxy) benzophenone A mixture of 3.0 parts 5(2H-benzotriazole-2-yl)2,2',4,4'-tetrahydroxybenzophenone, 1.2 parts glycidyl acrylate and 0.1 parts ammonium nitrate was heated for 7 hours at 80"C under a nitrogen atmosphere. The resulting crude product was dissolved in benzene and treated with 1 % sulfuric acid. The benzene layer was evaporated and the resulting product was recrystallized from ethanol to give a yellow viscous liquid with a yield of 56%.

Example 14 The preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention, i.e., 5 (2H -5-m ethoxybenzotri azol e-2-y1)2,2' ,4-tr ih yd roxy -4' (3 -acry i ox y-2- hydroxypropoxy)benzophenone The procedure of Example 13 was followed using an equivalent quantity of 5(2H-5 methoxybenzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone in place of 5(2Hbenzotriazol-1-yl)2,2',4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give a yellow viscous liquid with a yield of 61%.

Example 15 Preparation of a polymerizable ultraviolet absorbing compound according to a further embodiment of the invention, i.e., 5(2H-5-chlorobenzotriazole-2-yl)2,2' ,4-trihydroxy-4' (3-acryloxy-2-hydroxypropoxy) benzophenone The procedure of Example 13 was followed using an equivalent quantity of 5(2B-5- chlorobenzotriazole-2-yl)2,2 ' ,4,4' -tetrahydroxybenzophenone in place of 5(2H-benzotriazole- 2-yl)2,2',4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give a yellow viscous liquid with a yield of 52%.

Example 16 Preparation of a polymerizable ultraviolet absorbing compound according to a further embodiment of the invention, i.e., 5(2H-benzotriazole-2-yl)2,2',4-trihydroxy-4'-ss- hydroxyethoxybenzophenone To a stirred mixture of 3.0 parts 5(2H-benzotriazole-2-yl)2,2',4,4'- tetrahydroxybenzophenone and 0.4 parts sodium hydroxide in 100 parts by volume of water was added 1.0 part ethylene chlorohydrine. The mixture was heated for 4 hours at 85"C and allowed to stand over night at room temperature. The solid obtained was recrystallized from ethanol to give yellowish needles with a yield of 64%.

Example 17 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention, i.e., 5(2H-5-methoxybenzotriazole-2-yl)2,2' ,4-trihydroxy4'-ss-hydroxyethoxybenzophenone The procedure of Example 16 was followed using an equivalent quantity of 5(2B-5- methoxybenzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone in place of 5(2H benzotriazole-2-yl)2 ,2' ,4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give yellowish needles with a yield of 67%.

Example 18 Preparation of a polymerizable ultraviolet absorbing compound according to another embodiment of the invention, i.e., 5(2H-5-chlorobenzotriazole-2-yl)2,2' ,4-trihydroxy-4'-ss-hydroxyethoxybenzophenone The procedure of Example 16 was followed using an equivalent quantity of 5(2B-5- chlorobenzotriazole-2-yl)2,2' ,4,4'-tetrahydroxybenzophenone in place of 5(2H-benzotriazole 2-yl)2,2',4,4'-tetrahydroxybenzophenone. The resulting product was recrystallized from ethanol to give yellowish needles with a yield of 59%.

Example 19 Homopolymerization.

The monomers of Examples 4 and 7 were homopolymerized in toluene at 60"C for 120 hours using azobisizobutyronitrile (AIBN) as an initiator to obtain 100% conversion to a high molecular weight polymer having an inherent viscosity of 1.92 and 1.96 dl/g, respectively. The homopolymers were useful as an additive for incorporation in polymer films to enhance UV absorption properties. Similar procedures were followed in the homopolymerization of monomers in Examples 5, 6, 8, 9, 13, 14 and 15.

Example 20 Copolymerization.

The monomers of Examples 4 and 7 were copolymerized with styrene. 0.35 parts of the benzophenone-benzotriazole monomers were dissolved in 20 parts of dichloromethane containing 0.05 parts AIBN as an initiator and 9.65 parts of styrene and were placed in a pyrex tube. The tube was then degassed three times by freeze-thaw technique and then it was sealed under vacuum. The mixture was polymerized at 60"C for 60 hours. The polymers were then characterized by Gel Permeation Chromatography (GPC), UV-visible spectroscopy and HNMR. Results showed that the UV absorbers were chemically bonded to the polymer matrix. Similar procedures were followed in the copolymerization of monomers in Examples S to 15.

Example 21 The monomers of Examples 4 and 7 were copolymerized with MMA following the same copolymerization procedure as in Example 20. The resulting polymers containing 13 % and 15% of the benzophenone-benzotriazole monomer unit. Analysis showed that the UV absorbing group was also chemically bonded in the polymer matrix. Similarly, copolymerization of MMA with monomers in Examples 5 to 15 was also conducted.

Example 22 The monomer of Example 16 (0.90 parts) was copolymerized with unsaturated polyester during polyesterification reaction. 150 parts of phthalic anhydride, 108 parts of maleic anhydride, and 325 parts of propylene glycol were reacted for 1 hour at 200"C under a nitrogen atmosphere. The reactants were cooled to 1500C and 0.9 parts of monomer of Example 16 was added. The reaction mixture was then heated for another hour at 1600C before cooling to 100"C. After cooling, the product was thinned with 204 parts styrene monomer. Analysis of the polymer showed that the UV absorbing groups were chemically bonded in the polymer matrix. Similarly, monomers of Examples 17 and 18 could be copolymerized with unsaturated polyester resins.

Example 23 The Monomers of Examples 4 or 7 were grafted to polystyrene during processing.

One part of benzophenone-benzotriazole monomer (Example 4) was hot blended with 99 parts of polystyrene on a two roll mill at 1800C for 30 minutes. The blended mixture was then hot pressed in a compression molding machine at 1500C for 15 minutes or injection molded using an injection molding machine. The resulting polymer was then dissolved in methylene chloride and reprecipitated in methanol in order to separate the unreacted monomers. 85-86% of the added UV absorbing group was chemically bound to polystyrene. The result was confirmed by GPC. The experiment was repeated for 3% and 5% UV absorbing group (benzophenone-benzotriazole of Example 4) which were grafted to polystyrene. Monomers of Examples 5, 6, 8, 9, and 10-15 could be grafted into polystyrene using the same technique.

Example 24 A similar procedure to the one in example 23 was followed to graft the UV-absorbing benzophenone-benzotriazoles of examples 4 to 15 to polyethylene.

Example 25 Grafting to dehydrochlorinated PVC.

4.17 parts of PVC were dissolved in 1 liter of pyridine. The reaction mixture was heated to 125 CC for 3.5 hours under a nitrogen atmosphere. The color of the reactant changed from colorless to yellow and then to red-brown. The dehydrochlorinated PVC was precipitated in methanol, filtered off, washed with methanol several times and dried under vacuum for 48 hours. The product was then dissolved in THF, reprecipitated in petroleum ether and filtered off before drying in vacuum at 500C for 3 hours and at room temperature for 3 days.

In a 100 ml beaker equipped with stirrer, 2 parts of the dehydrochlorinated PVC was dissolved in 40 ml pure THF. 0.1 parts of benzophenone-benzotriazole monomer (Example 43 and 0.01 parts AIBN were added. The reaction mixture was then transferred to a pyrex tube and degassed three times by freeze thaw technique and sealed under vacuum. The sealed tube was heated in a water bath at 650C for 48 hours. The tube content was precipitated in petroleum ether and filtered off. The produced polymer was then washed with dichloromethane and then dissolved in T11F and reprecipitated in petroleum ether. The polymer was then dried in a vacuum oven at room temperature for 48 hours. GPC showed that the UV absorbing group was chemically bonded into the proper matrix. Similar techniques were used for other monomers in Examples 5-15.

Example 26 0.65 to 1.3 parts of benzophenone-berizotriazole monomer (Example 4) was dissolved in 65 parts of a mixture consisting of 60 parts of unsaturated polyester resin and 40 parts of styrene monomer.

2 parts of methyl ethyl ketone peroxide and 0.1 part of cobalt octoate were added to the reaction mixture and stirred thoroughly. The mixture was then poured into 8 x 8 cm mold size before gelation. The reaction mixture was left overnight at room temperature in order to achieve full curing of the polyester resin. The resulting thermoset polymer was subjected to extraction by dichloromethane in order to separate the unreacted benzophenone-benzotriazole monomer. The resulting polymer containing 90-93% of UV absorbing group chemically bound to the polymer backbone. Similarly, monomers of Examples 5-15 could be used to stabilize unsaturated polyester resins.

Example 27 Extinction coefficients of benzophenone-benzotriazole monomers were measured in chloroform solution. The extinction coefficient ( > is a measure of the molar absorptivity of a compound according to the following equation: A = SCL wherein A = absorbance; C = concentration of the solute (moll); and L = path length of radiation within the sample (cm).

Absorbance is determined according to conventional procedures using a UV visible spectrophotometer. Since s is proportional to absorbance, a compound which has a large S gives greater UV absorption at lower concentrations.

The monomers of the present invention absorb sharply in the UV range of 250400 nm and cut off sharply at 400 nm. The extinction coefficient value for compounds of Examples 1, 4, 5 and 16 are summarized in the following table in comparison to hydroxy benzophenone monomer and hydroxyphenyl benzotriazole monomer.

Table 1. UV Extinction Coefficients UV Absorber Ajax, e(Lmo1~' cm-' Amax2 eSmol-l cm-' nm at Ajax, nm at #max2 Example 1 290 3.6 x 104 330 3.4 x 104 Example 4 292 3.3 x 104 335 3.4 x 104 Example 5 292 3.7 x 104 335 3.2 x 104 Example 16 293.5 3.6 x 104 336 3.4 x 104 Hydroxy benzophenone monomer 285 0.9 x 104 323 1.0 x 104 Hydroxypheyl benzotriazole monomer 296 1.1 x 104 341 2.3 x 104 The polymerizable UV absorbing compounds disclosed herein include benzophenone and benzotriazole moeities in one molecule, and have extinction coefficients which are considerably higher than the commercially available benzophenones or benzotriazoles. For example, the extinction coefficients of the compounds disclosed herein range from about 3.2 to about 3.7 x 104 lit per mole per centimeter. In other words, the absorptivity is very high at low concentrations. For comparison, the extinction coefficients of commercial benzophenones and benzotriazoles are 1 x 104 and 2.3 x 104 lit mole-1cm-1; respectively.

Thus, the compounds disclosed herein offer an increase in stabilizer efficiency as compared to the commercially available benzotriazoles and benzophenones.

It should also be recognized that using high dosage of UV absorbers leads to increased incompatability, phase separation and leaching out of the UV absorbers from a polymer matrix which in turn results in less stability and increased costs. And, the effect of using a combination of commercially available benzotriazole and benzophenones does not appear to overcome those problems. However, the compounds disclosed herein overcome such problems because a relatively low dosage is required to achieve excellent stability for the polymer and, secondly, because the compounds disclosed herein have a dual effect due to the existence of both moieties in one molecule and the presence of polymerizable functional groups, which tend to overcome problems of incompatability.

It is also presently believed that the ultraviolet absorbing compounds disclosed herein offer a number of advantages over the UV light absorbers which contain two benzotriazole moieties. For example, the UV stabilizers disclosed herein function in two distinct modes.

The first involves the achievement of UV stabilization through keto-enol formation mechanism betweeen the hydroxy group at the 2-positions and the carbonyl group of the benzophenone moiety. The second mode involves intramolecular hydrogen bond formation between the hydroxyl group at 4-position with the azo nitrogen of the benzotriazole. By contrast, the absorbers having two benzotriazole moieties function through the second mode only (intramolecular hydrogen bond formation). Thus, the UV stabilization of such compounds may be rendered non-functional if the intramolecular hydrogen bond is prevented by external forces.However, with applicants' compounds, even if such preventions occur, the UV stabilization still functions through the first mode (i.e., keto-enol formation mechanism) Also, the compounds, according to the present invention, have a hydroxyl group at the 4'-position of the benzophenone moiety which is a full pendant group. Thus, a polymerizable functional group could be introduced easily to this pendant hydroxyl group, giving high yield and leaving the sterically hindered hydroxyl groups untouched unlike the stabilizer having the two benzotriazole moieties.

Finally, benzotriazole W absorbers are useful stabilizers for certain types of polymeric systems and that benzophenone UV absorbers are useful for other types of polymers. Thus, the compounds disclosed herein could be used for a wide range of polymeric systems, as they contain both benzotriazole and benzophenone moieties in one molecule.

While the invention has been described in connection with its preferred embodiments, it should be understood that changes and modifications can be made without departing from the scope of the invention.

Claims (31)

CLAIMS:

1. A compound having the formula

wherein R is hydrogen, halogen or alkoxy and R1 is hydrogen, acryloyl, methacryloyl, allyl, a- acryloyloxy p-hydroxypropyl, or P-hydroxyethyl.

2. A compound as claimed in claim 1 wherein R1 is an acryloyl group.

3. A compound as claimed in claim 1 or claim 2, being 5(2H-benzotriazole-2-yl)2,2',4-trihydroxy-4'- acryloxybenzophenone, 5(2H-5-methoxybenzotriazole-2 yl)2,2',4-trihydroxy-4'-acryloxybenzophenone, 5 (2H-5- chlorobenzotriazole-2-yl) 2,2' , 4-trihydroxy-4 '- acryloxybenzophenone or a homopolymer thereof.

4. A compound as claimed in claim 1 wherein R1 is a methacryloyl group.

5. A compound as claimed in claim 1 or claim 4, being 5 (2H-benzotriazole-2-yl) 2,2' , 4-trihydroxy-4' - methacryloxybenzophenone, 5(2H-5-methoxybenzotriazole-2 yl)2,2',4-trihydroxy-4'-methacryloxybenzophenone, 5(2H5-chlorobenzotriazole-2-yl)2,2',4-trihydroxy-4'- methacryloxybenzophenone, or a homopolymer thereof.

6. A compound as claimed in claim 1 wherein R1 is an allyl group.

7. A compound as claimed in claim 1 or claim 6, being 5 (2H-benzotriazole-2-yl) 2,2' ,4-trihydroxy-4' - allyloxybenzophenone, 5(2H-5-methoxybenzotriazole-2 yl)2,2',4-trihydroxy-4'-allyloxybenzophenone, or 5 (2H-5- chlorobenzotriazole-2-yl) 2,2' , 4-trihydroxy-4 '- allyloxybenzophenone, or a homopolymer thereof.

8. A compound as claimed in claim 1 wherein R1 is a- acryloyloxy p-hydroxypropyl.

9. A compound as claimed in claim 1 or claim 8, being 5(2H-benzotriazole-2-yl)2,2',4-trihydroxy-4'-(3- acryloxy-2-hydroxypropoxy)benzophenone, 5 (2H-5- methoxybenzotriazole-2-yl)2,2',4-trihydroxy-4'-(3- acryloxy-2-hydroxypropoxy)benzophenone, 5 (2H-5- chlorobenzotriazole-2-yl)2,2',4-trihydroxy-4'-(3- acryloxy-2-hydroxypropoxy)benzophenone, or a homopolymer thereof.

10. A compound as claimed in claim 1 wherein R1 is p- hydroxyethyl.

11. A compound as claimed in claim 1 or claim 10, being 5(2H-benzotriazole-2-yl)2,2',4-trihydroxy-4'-ss- hydroxyethoxy benzophenone, 5(2H-5-methoxybenz 5(2H-5-methoxybenzotriazole- 2-y1)2,2',4-trihydroxy-4'-ss-hydroxyethoxybenzophenone, or 5(2H-5-chlorobenzotriazole-2-yl)2,2',4-trihydroxy-4'- p-hydroxyethoxybenzophenone, or a homopolymer thereof.

12. A compound as claimed in claim 1, being 5(2Hbenzotriazole-2-yl)2,2','4,4'-tetrahydroxybenzophenone.

13. A compound as claimed in claim 1, being 5(2H-5 methoxybenzotriazole-2-yl) 2,2' 1414' - tetrahydroxybenzophenone.

14. A compound as claimed in claim 1, being 5(2H-5 chlorobenzotriazole-2-yl) 2,2' ,4,4' - tetrahydroxybenzophenone.

15. An ultraviolet light absorbing compound as claimed in claim 1 substantially as herein described and with reference to the Examples.

16. An ultraviolet light absorbing composition being or comprising a copolymer of a compound as claimed in any one of the preceding claims.

17. An ultraviolet light absorbing composition comprising an organic polymer and a homopolymer of a compound as claimed in any one of claims 1 to 15 in an amount of from 0.5 to 5 percent by weight.

18. A composition as claimed in 17 wherein said homopolymer is present in an amount of from 0.5 to 2 percent by weight.

19. An ultraviolet light absorbing composition as claimed in claim 16 being or comprising a copolymer of a compound as claimed in any one of claims 1 to 15 and a monomer selected from styrene, methylmethacrylate, acrylate, methylstyrene, acrylamide, acrylonitrile, methacrylonitrile, vinylacetate, vinylidene chloride, vinyl chloride, ethylene, propylene and mixtures thereof, wherein the compound as claimed in any one of claims 1 to 15 is present in an amount of about 0.5 20% by weight.

20. An ultraviolet light absorbing composition being or comprising a copolymer of an unsaturated polyester resin and from about 0.5 to 10% by weight of a compound as claimed in claim 11.

21. An ultraviolet light absorbing composition being or comprising a graft copolymer of a compound as claimed in any one of claims 1 to 15 in an amount of from about 0.5 to 10% by weight and a polymer selected from polyolefin, polyvinyl halide, polystyrene, polyvanilidene halide, polyacrylates and mixtures thereof and unsaturated polyester resins in an amount of from about 90 to 99.5% by weight.

22. An ultraviolet light absorbing composition as claimed in claim 16 substantially as herein described and with reference to the Examples.

23. A polymeric material comprising a compound as claimed in claim 1.

24. A method for preparing a compound as claimed in claim 1, said method comprising a) coupling a compound of formula

(wherein R2 is hydrogen, acryloyl, methacryloyl, allyl, a-acryloyloxy ss-hydroxypropyl or p-hydroxyethyl) with a diazonium derivative of a compound of formula

(wherein R is defined as in claim 1); b) reducing the thus produced intermediate to form the triazolyl derivative; and c) esterifying or etherifying said triazolyl derivative to produce a corresponding compound in which R2 is acryloyl, methacryloyl, allyl, a-acryloyloxy ss-hydroxypropyl or p-hydroxyethoxy).

25. A method as claimed in claim 24 substantially as herein described with reference to the Examples.

26. A method for producing a benzophenone-benzotriazole compound, said method comprising the steps of forming a benzophenone azo compound by the coupling reaction of diazonium salt of 0-nitroaniline or its chloro- or methoxy- derivatives with 2,2',4,4'tetrahydroxybenzophenone at 0 to 5"C for 3 to 6 hours so that the coupling takes place mainly at one of the 4positions of the 2,2',4,4'-tetrahydroxybenzophenone and triazolizing the resulting benzophenone azo compound using zinc powder in an aqueous sodium hydroxide solution at 20 to 30 C for 8 to 10 hours.

27. A method for producing a benzophenone-benzotriazole compound, said method comprising the steps of: a) diazotizing 2-nitroaniline with sodium nitrite and concentrated hydrochloric acid in water to form a solution; b) adding 2,2',4,4'-tetrahydroxybenzophenone in ethanol and sodium bicarbonate in water to the solution of step (a) and cooling to a temperature of about 5"C; c) isolating an intermediate azo compound by filtration and dissolving it in a sodium hydroxide solution; d) triazolizing the solution from step (c) by the addition of zinc dust and removing the zinc; e) acidifying the filtrate from step (d) with concentrated hydrochloric acid and collecting the solid product; and f) recrystallizing the product from step (e) from a mixture of ethanol and water.

28. A method for producing a W absorbing compound, said method comprising the steps of: a) mixing 5 (2H-benzotriazole-2-yl) 2,2',4,4'- tetrahydroxybenzophenone with sodium hydroxide in water; b) stirring the mixture of step (a) and adding a mixture of acryloyl chloride in chloroform dropwise and stirring at room temperature until the reaction is complete; c) isolating the organic layer and drying the organic layer by evaporation; and d) recrystallizing the product from step (c) from a mixture of alcohol and water to thereby form a product.

29. A method for producing a W absorbing compound, said method comprising; a) mixing 5(2H-benzotriazole-2-yl) 2,2',4,4'- tetrahydroxybenzophenone with potassium carbonate in acetone; b) adding allyl bromide and heating at the reflux temperature with stirring until the reaction is complete; c) adding water to the mixture and extracting with diethylether; d) evaporating the ether to obtain a product; and e) recrystallizing the product from step (d) from ethanol to thereby form a final product.

30. A method for producing a W absorbing compound, said method comprising the steps of; a) mixing about 3.0 parts by weight of 5(2H benzotriazole-2-yl)2,2',4,4' tetrahydroxybenzophenone and about 0.8 parts sodium hydroxide in about 100 parts of water; b) adding about 1.0 parts by weight ethylene chlorohydrin; c) heating the mixture from step (b) at about 85"C; d) allowing the mixture from step (c) to stand at room temperature for about 16 hours to produce a solid; and e) recrystallizing the solid from step (d) from ethanol to obtain a product.

31. A method of preparing an ultra violet light absorbing composition, said method comprising addition, graft or condensation polymerizing or cross-linking a compound as claimed in claim 1 or a homopolymer thereof with an ethylenically unsaturated compound or an organic polymer.