BENZYLFORMAMIDINE COMPOUNDS AND PLASTIC

PRODUCTS CONTAINING THE BENZYLFORMAMIDINE

COMPOUNDS AS ULTRAVIOLET LIGHT ABSORBERS Technical Field [1] The present invention relates to benzylformamidine compounds useful as ul¬ traviolet light absorbers. More particularly, the present invention relates to benzyl¬ formamidine compounds having high ultraviolet light absorption and superior thermal stability that can be suitably used as ultraviolet light absorbers for a variety of plastic products which undergo high-temperature treatment or require superior thermal stability, and plastic products containing the benzylformamidine compounds as ul¬ traviolet light absorbers. Background Art [2] In general, it is widely known that the physical properties of a number of synthetic resin products, natural resin products and polymerizable polymeric products (hereinafter, referred collectively to as 'plastic products') are deteriorated by the action of photodegradation caused upon exposure to UV light, thus causing a rapid dete¬ rioration in the durability of the plastic products. Particularly, photodegradation caused in plastic products induces discoloration and/or decoloration of the products and makes the products susceptible to externally applied impacts. To solve these problems, ul¬ traviolet light absorbers are added in the course of the manufacture of a variety of plastic products. [3] There have been known many compounds associated with ultraviolet light absorbers. As one prior art in connection with the present invention, U.S. Patent No. 4,021,471 discloses a formamidine as an ultraviolet light absorber, represented by Formula 1: [4] Formula 1

[5] wherein R is selected from C alkyl radicals, B is selected from H, OH, Cl and methoxy, R is selected from C alkyl radicals and phenyl radicals, A is selected from hydrogen, carboethoxy, carbobutoxy, methoxy, ethyl, dimethylamino and chlorine, and D is selected from H, OCH and Cl. [6] The ultraviolet light absorber having the structure shown in Formula 1 can be usefully applied to the production of various synthetic resin products and poly- merizable polymer products due to its superior photostability. Disclosure of Invention Technical Problem [7] However, since most ultraviolet light absorbers, including the ultraviolet light absorber having the structure shown in Formula 1, do not show sufficiently satisfactory thermal stability, they are largely limited in their application to plastic products undergoing high-temperature treatment or requiring superior thermal stability. [8] Accordingly, taking into consideration the fact that most plastic products are subjected to processing at high temperatures, there exists a strong need for an ul¬ traviolet light absorber having not only high ultraviolet light absorption but also superior thermal stability. In order to satisfy this need, the present inventor has performed extensive research to develop an ultraviolet light absorber having high ul¬ traviolet light absorption and superior thermal stability, thus achieving the present invention. Technical Solution [9] Thus, it is an object of the present invention to provide benzylformamidine compounds having high ultraviolet light absorption and superior thermal stability that can be suitably used as ultraviolet light absorbers for a variety of plastic products which undergo high-temperature treatment or require superior thermal stability. [10] It is another object of the present invention to provide plastic products containing the benzylformamidine compounds as ultraviolet light absorbers. [11] In accordance with one aspect of the present invention for achieving the above objects, there is provided a benzylformamidine compound represented by Formula 2 below: [12] Formula 2

[13] wherein R and R are each independently selected from hydrogen, C 1—9 alkyl, and C carboalkoxy; L and L are each independently selected from hydrogen and C alkyl; and L is selected from H and OH. [14] The benzylformamidine compound of Formula 2 used as an ultraviolet light absorber shows excellent thermal stability and high ultraviolet light absorption as compared to the conventional formamidine compound of Formula 1. Accordingly, the benzylformamidine compound of Formula 2 can be suitably used as an ultraviolet light absorber in the manufacture of plastic products which undergo high-temperature treatment or require superior thermal stability. [15] In accordance with another aspect of the present invention, there is provided a plastic product manufactured by adding the benzylformamidine compound of Formula 2 as an ultraviolet light absorber during molding of plastic raw materials selected from synthetic resins, natural resins and polymerizable polymers. [16] Since the benzylformamidine compound of Formula 2 has superior thermal stability and high ultraviolet light absorption, the use of the benzylformamidine compound as an ultraviolet light absorber in the manufacture of plastic products, which undergo high-temperature treatment, allows the plastic products to have high ultraviolet light absorption , thus enhancing the durability of the plastic products. [17] Benzylformamidine compounds of the present invention will now be explained in more detail. [18] The present invention provides a benzylformamidine compound that can be useful as an ultraviolet light absorber, represented by Formula 2 below: [19] Formula 2

[20] wherein R and R are each independently selected from hydrogen, C alkyl, and C carboalkoxy; L and L are each independently selected from hydrogen and C 1-4 alkyl; and L is selected from H and OH. [21] Among benzylformamidine compounds that can be represented by Formula 2, preferred is a compound of Formula 3 (wherein R is carboethoxy in Formula 2) below: [22] Formula 3

[23] wherein R is selected from hydrogen, C alkyl, and C carboalkoxy; L and L 1-9 1-4 are each independently selected from hydrogen and C alkyl; and L is selected from H and OH. [24] Among compounds that can be represented by Formula 3, preferred are benzyl- formamidine compounds of Formulae 4 to 6 (wherein R is hydrogen, carboethoxy, and carbobutoxy in Formula 3, respectively) below: [25] Formula 4

[26] wherein L and L are each independently selected from hydrogen and C alkyl; 1-4 and L L2 i iss s seelleecctted from H and OH; [27] Formula 5

[28] wherein L , L , and L are as defined in Formula 4; and [29] Formula 6

1 1J ^ [30] wherein L , L , and L are as defined in Formula 4. [31] Among benzylformamidine compounds that have the structure shown in Formula 4, a particularly preferred compound is Λf-3,5-di-teτt-butyl-4-hydroxybenzyl-/V' - 4-ethoxycarbonylphenyl- JV-phenylformamidine of Formula 7 (wherein L and L are t ■ butyl, and L is OH in Formula 4) below: [32] Formula 7

[33] Among benzylformamidine compounds that have the structure shown in Formula 5, more preferred compounds are Λ/,./V'-bis(4-ethoxycarbonylphenyl)-/V' - benzylformamidine of Formula 8 (wherein L , L , and L are hydrogen in Formula 5) below: [34] Formula 8

[35] ; and [36] N,N' -bis(4-ethoxycarbonylphenyl)-N-3,5-di-te7t - butyl-4-hydroxybenzylformamidine of Formula 9 (wherein L and L are ?-butyl, and L is OH in Formula 5) below: [37] Formula 9

[38] Among benzylformamidine compounds that have the structure shown in Formula 6, a preferred compound is N-4-butoxycarbonylphenyl-N'-4-ethoxycarbonylphenyl- N - 3,5-di-ter?-butyl-4-hydroxybenzylformamidine of Formula 10 (wherein L and L are t ■ butyl, and L is OH in Formula 6) below: [39] Formula 10 [40] Since the benzylformamidine compounds according to the present invention show high ultraviolet light absorption and excellent thermal stability as compared to con¬ ventional formamidine compounds, they can be suitably used as ultraviolet light absorbers in the manufacture of synthetic resin products and polymer products which undergo high-temperature treatment or require superior thermal stability. [41] The benzylformamidine compound of Formula 2 according to the present invention can be easily prepared through the following reactions sequence: [42] Reaction 1

[43] Reaction 2

[44] Reaction 3

[45] In Reactions 1 to 3, R , R , L , L and L are as defined in Formula 2. [46] Since the benzylformamidine compounds of the present invention show excellent thermal stability and high ultraviolet light absorption as compared to conventional formamidine compounds, they can be suitably used as ultraviolet light absorbers in the manufacture of plastic products which undergo high-temperature treatment or require superior thermal stability. [47] The benzylformamidine compounds of the present invention can be added as ul- traviolet light absorbers in the manufacture of plastic products from plastic raw materials selected from synthetic resins, natural resins and polymerizable polymers. Particularly, since the benzylformamidine compounds are highly compatible with polyurethanes and polyols, which are raw materials of polyurethanes, they can be suitably used as ultraviolet light absorbers for polyurethanes undergoing high- temperature treatment. If necessary, the benzylformamidine compounds may be used as ultraviolet light absorbers for cosmetics, as well as for plastic products. [48] The benzylformamidine compounds are added as ultraviolet light absorbers during manufacture of plastic products. At this time, the benzylformamidine compounds are added in common amounts and preferably in amounts of 0.1-5.0 parts by weight, based on 100 parts by weight of the solid content of plastic raw materials. Description of Drawings [49] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [50] Figs. 1 to 4 are 1H-NMR spectra (CDCl , 200 MHz) of compounds prepared in Examples 1 to 4 of the present invention, respectively; [51] Fig. 5 is a graph comparing the ultraviolet light absorbance of a benzyl¬ formamidine compound of the present invention and a conventional formamidine compound; and [52] Fig. 6 is a graph comparing the thermal stability of a benzylformamidine compound of the present invention and a conventional formamidine compound. Best Mode [53] Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples serve to assist the understanding of the present invention and they are not to be construed as limiting the scope of the invention. [54] <Example 1> [55] Preparation of Λ/,Λ^-bis(4-ethoxycarbonylphenyl)-Λ^-benzylformamidine [56] 329.58g of benzocaine was dissolved in 800 ml of toluene at 43°C + 3°C with stirring, and then 118.78g of 85% formic acid was added dropwise thereto. The mixture was reacted at 100°C + 50C for 2 hours to obtain a solid product (a). [57] The solid product (a) was dissolved in 500 ml of toluene with stirring, and then an aqueous solution of ^-butylammonium bromide (8.12g) and NaOH (150.04g) in 200 ml water was added dropwise thereto, followed by the addition of benzyl bromide (170.04g). The mixture was reacted for 1.5 hours with stirring. The resulting organic layer was separated from the reaction mixture, dried and evaporated under reduced pressure to obtain a solid product (b). [58] The obtained solid product and benzocaine were dissolved in 500 ml of toluene at 30°C with stirring, and then 340.44g of POCl was added dropwise thereto. The mixture was reacted at 70°C + 3°C for 5 hours with stirring. The resulting solution was added dropwise to 500 ml of a 20% aqueous NaOH solution at 20°C. The resulting organic layer was separated from the reaction mixture, washed with 300 ml of a saturated brine solution, dried over Na SO , filtered, and evaporated under reduced 2 4 pressure to obtain a crude product. [59] The crude product was recrystallized from a solution of ethylacetate (EA) and hexane (Hex) (1:1) to afford 325.5g (yield: 37.8%) of a final solid product. [60] The structure of the solid product was identified by H NMR spectroscopy (CDCl , 200 MHz). The H NMR spectrum is shown in Fig. 1. The specific data are as follows. [61] 1 H NMR (CDCl , 200MHz) δ: 1.36-1.43 (m, 6H), 4.29-4.40 (m, 4H), 7.06 (d, 2H, / = 6.8Hz), 7.19 (d, 2H, /= 8.7Hz), 7.31-7.34 (m, 5H), 7.98 (d, 2H, / = 2.2Hz), 8.00 (d, 2H, / = 2.0Hz), 8.37 (s, IH) [62] The structure of the solid product was identified by H NMR spectroscopy (CDCl , 200 MHz). The H NMR spectrum is shown in Fig. 1. The specific data are as follows. [63] The NMR analysis indicates that the solid product is N,N' - bis(4-ethoxycarbonylphenyl)-Λf'-benzylformamidine of Formula 8. [64] <Example 2> [65] Preparation of N-3,5-di-ter?-butyl-4-hydroxybenzyl-N'-4-ethoxycarbonylpheny l- N - phenylformamidine [66] 40.0Og of 2,6-di-teτt-butyl-4-methylphenol and 36. Ig of Λf-bromosuccinimide were added to 400 ml of chloroform, and then 2.9Og of 2,2'-azobisisobutyronitrile was added thereto with stirring. The reaction mixture was refluxed for 19 hours. After the reaction mixture was cooled and filtered, the obtained filtrate was washed with 400 ml of water. The resulting organic layer was separated from the reaction mixture, dried over Na SO 2 4 , dried, and evaporated under reduced pressure to obtain 51.50g (yield: 94%) of a solid product (a). [67] Separately, 14.6 ml of aniline was added to 80 ml of toluene, and then 9.70 ml of formic acid was added dropwise thereto. The mixture was reacted at 100°C + 5°C for 2 hours, and water was removed from the reaction mixture. Thereafter, the reaction mixture was allowed to cool to room temperature, filtered, and washed with water to obtain a solid product (b). [68] The solid product (b) was dissolved in 80 ml of toluene with stirring, and then an aqueous solution of ^-butylamino bromide (4.9Og) and NaOH (5.60g) in 100 ml of water was added dropwise thereto, followed by the addition of 20.Og of the solid product (a). The mixture was reacted for 2 hours with stirring. The resulting organic layer was separated from the reaction mixture, dried over Na 2 SO 4 , and evaporated under reduced pressure to obtain 12. Ig (yield: 53%) of a solid product (c). [69] The solid product (c) and 9.3g of benzocaine were dissolved in 200 ml of toluene at 40°C with stirring, and then 7.20 ml of POCl was added dropwise thereto. The mixture was reacted at 70°C + 3°C for 6 hours with stirring. The resulting solution was added dropwise to 270 ml of a 10% aqueous NaOH solution at 20°C. The resulting organic layer was separated from the reaction mixture, washed with 80 ml of a saturated brine solution, dried over Na SO , filtered, and evaporated under reduced pressure to obtain 2 4 a crude product. [70] The crude product was recrystallized from a solution of EA and Hex (1:7) to afford 10.8g (yield: 43%) of a final solid product. [71] The structure of the solid product was identified by H NMR spectroscopy (CDCl , 200 MHz). The H NMR spectrum is shown in Fig. 2. The specific data are as follows. [72] * H NMR (CDCl , 200MHz) δ: 1.35-1.42 (m, 21H), 4.35 (q, 2H, J = 7.0Hz), 5.12 (s, IH), 5.15(s, 2H). 7.05 (d, 2H, J = 8.3Hz), 7.12 (s, 2H), 7.15-7.34 (m, 5H), 7.99(d, 2H, J = 8.7Hz), 8.15 (s, IH) [73] The NMR analysis indicates that the solid product is N-3,5-di-tert - butyl-4-hydroxybenzyl-N'-4-ethoxycarbonylphenyl- JV-phenylformamidine of Formula 7. [74] <Example 3> [75] Preparation of Λ/,Λ^-bis(4-ethoxycarbonylphenyl)-N-3,5-di-te7t - butyl-4-hydroxybenzylformamidine [76] 10.0g of benzocaine was dissolved in 50 ml of toluene at 43°C + 3°C with stirring, and then 7.2 ml of formic acid was added dropwise thereto. The mixture was reacted at 100°C + 5°C for 2 hours, and water was removed from the mixture. Thereafter, the reaction mixture was allowed to cool to room temperature, filtered, and washed with water to obtain 10.2g (yield: 88%) of a solid product (a). [77] The solid product (a) was dissolved in 20 ml of toluene with stirring, and then an aqueous solution of ^-butylammonium bromide (l.lg) and NaOH (1.26g) in 100 ml of water were added dropwise thereto, followed by the addition of 3,5-di-tert - butyl-hydroxybenzyl bromide (4.5g). The mixture was reacted for 2 hours with stirring. The resulting organic layer was separated from the reaction mixture, dried over Na SO , and evaporated under reduced pressure to obtain 3.35g (yield: 55%) of a 2 4 solid product (b). [78] The solid product (b) and 1.4g of benzocaine were dissolved in 100 ml of toluene at 40°C with stirring, and then 1.1 ml of POCl was added dropwise thereto. The mixture was reacted at 70°C + 3°C for 6 hours with stirring. The resulting solution was added dropwise to 75 ml of a 10% aqueous NaOH solution at 20°C. The resulting organic layer was separated from the reaction mixture, washed with 50 ml of a saturated brine solution, dried over Na 2 SO 4 , filtered, and evaporated under reduced pressure to obtain a crude product. [79] The crude product was recrystallized from a solution of EA and Hex (1:6) to afford 2.Og (yield: 45%) of a final solid product. [80] The structure of the solid product was identified by H NMR spectroscopy (CDCl , 200 MHz). The H NMR spectrum is shown in Fig. 3. The specific data are as follows. [81] 1 H NMR (CDCl , 200MHz) δ: 1.33-1.44 (m, 24H), 4.36 (q, 4H, J = 6.8Hz), 5.14 (s, IH), 5.23(s, 2H). 7.05 (d, 2H, J = 12.9Hz), 7.12 (s, 2H), 7.22 (d, 2H, J = 11.2Hz), 7.98(d, 4H, J = 9.9Hz), 8.30 (s, IH) [82] The NMR analysis indicates that the solid product is N,N' - bis(4-ethoxycarbonylphenyl)-N-3,5-di-ter?-butyl-4-hydroxyben zylformamidine of Formula 9. [83] <Example 4> [84] Preparation of N-4-butoxycarbonylphenyl-N'-4-ethoxycarbonylphenyl- JV-3,5-di- teτt-butyl-4-hydroxybenzylformamidine [85] 17.4g of benzocaine was dissolved in 20 ml of toluene at 43°C + 3°C with stirring, and then 5.4 ml of formic acid was added drop wise thereto. The mixture was reacted at 100°C + 5°C for 2 hours, and water was removed from the reaction mixture. Thereafter, the reaction mixture was allowed to cool to room temperature, filtered, and washed with water to obtain 19.6g (yield: 98%) of a solid product (a). [86] 12.6g of the solid product (a) was dissolved in 150 ml of toluene with stirring, and then an aqueous solution of ^-butylammonium bromide (4.2g) and NaOH (4.8g) in 80 ml of water was added dropwise thereto, followed by the addition of 3,5-di-tert - 4-hydroxybenzyl bromide (17.Og). The mixture was reacted for 2 hours with stirring. The resulting organic layer was separated from the reaction mixture, dried over Na SO 2 4 , and evaporated under reduced pressure to obtain 13.2g (yield: 53%) of a solid product (b). [87] The solid product (b) and 5.5g of benzocaine were dissolved in 100 ml of toluene at 40°C with stirring, and then 4.2g ml of POCl was added dropwise thereto. The mixture was reacted at 70°C + 3°C for 6 hours with stirring. The resulting solution was added dropwise to 250 ml of a 10% aqueous NaOH solution at 20°C. The resulting organic layer was separated from the reaction mixture, washed with 50 ml of a saturate d brine solution, dried over Na SO , filtered, and evaporated under reduced pressure to obtain a crude product. [88] The crude product was recrystallized from a solution of EA and Hex (1:5) to afford 9.5g (yield: 53%) of a final solid product. [89] The structure of the solid product was identified by H NMR spectroscopy (CDCl , 200 MHz). The H NMR spectrum is shown in Fig. 4. The specific data are as follows. [90] 1 H NMR (CDCl , 200MHz) δ: 0.97 (t, 3H, J = 7.2HZ), 1.36-1.53 (m, 23H), 1.64-1.82 (m, 2H), 4.28-4.42 (m, 4H), 5.14 (s, IH), 5.23(s, 2H). 7.06 (d, 2H, J = 8.5Hz), 7.12 (s, 2H), 7.23 (d, 2H, J = 8.8Hz), 8.01(d, 4H, J = 9.1Hz), 8.30 (s, IH) [91] The NMR analysis indicates that the solid product is Λf-4-butoxycarbonylphenyl-/V' -4-ethoxycarbonylphenyl- Λf-3,5-di-teτt-butyl-4-hydroxybenzylformamidine of Formula 10. [92] Experimental Example 1> [93] The compound N,N' -bis(4-ethoxycarbonylphenyl)-Λ^-benzylformamidine of Formula 8 prepared in Example 1 and the compound ,/V-(4-ethoxycarbonylphenyl)-./V' - methyl-N'-phenylformamidine of Formula 11 as a conventional ultraviolet light absorber were measured for UV absorbance and thermal stability. [94] The UV absorbance was measured using a solution of 1 mg of each sample in chloroform (100 ml). The measurement was conducted using a UV spectrometer (Bechman Du-600). The results are shown in Fig. 5. The thermal stability was measured under a nitrogen atmosphere by thermal gravimetric analysis (Rerkin-Elmer TGA7) while the temperature of each sample was elevated at a rate of 15 °C/min. The results are shown in Table 1 and Fig. 6. [95] Formula 11

[97] As is apparent from Fig. 5, the ultraviolet light absorbance of the compound N,N' - bis(4-ethoxycarbonylphenyl)-Λf'-benzylformamidine according to the present invention is comparable to that of the compound JV-(4-ethoxycarbonylphenyl)-./V'-methyl-/V' - phenylformamidine. [98] In contrast, as can be seen from the results shown in Table 1 and Fig. 6, the thermal stability of the compound Λ/,Λ^-bis(4-ethoxycarbonylphenyl)-Λ^-benzylformamidine according to the present invention is superior to that of Λf-(4-ethoxycarbonylphenyl)-/V' -methyl-Λf'-phenylformamidine. [99] Experimental Example 2> [100] Each of the compound Λ/,Λ^-bis(4-ethoxycarbonylphenyl)-Λ^-benzylformamidine of Formula 8 prepared in Example 1 and the compound N-(4-ethoxycarbonylphenyl)-N' - methyl-N'-phenylformamidine of Formula 11 was added as an ultraviolet light absorber during the production of polyurethane urea elastic fibers. [101] Specifically, one mole of polytetramethyleneglycol (molecular weight: 1,800) and 1.7 moles of 4,4-diphenylmethanediisocyanate were mixed and then allowed to react at 90°C for 90 minutes to prepare a prepolymer having isocyanate groups at both terminals. After the prepolymer was cooled to 40°C, N,N'-dimethylacetamide was added to prepare a ca. 45% prepolymer solution. The prepolymer solution was cooled to 5°C. To the prepolymer solution was slowly added a solution of 96% eq. of ethylenediamine and 6% eq. of diethylamine in N,N'-dimethylacetamide, based on the equivalents of the prepolymer, with vigorous stirring to extend and terminate the chain of the prepolymer, affording a polyurethaneurea solution. To the polyurethaneurea solution, each of the compound Λ/,./V'-bis(4-ethoxycarbonylphenyl)-/V' - benzylformamidine of Formula 8 prepared in Example 1 and the compound N - (4-ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine of Formula 11 was added as an ultraviolet light absorber in the respective amounts indicated in Table 2 below, based on the solid content (100 parts by weight). The mixtures were spun to produce respective polyurethaneurea elastic fibers. [102] The polyurethaneurea elastic fibers (40 deniers) were exposed to UV light using a fade-o-meter, which uses a Xenon arc light, for 40 hours. The changes in color (Δb values) were measured before and after treatment with a color master (Scinco Co., Ltd., Korea). The results are shown in Table 2 below. [103] Table 2

[104] As can be seen from the data shown in Table 2, based on excellent heat resistance of the benzylformamidine compound of the present invention, the final products using the benzylformamidine ultraviolet light absorber show excellent performance as compared to those using the conventional phenylformamidine ultraviolet light absorber in the same amounts as the benzylformamidine ultraviolet light absorber. Industrial Applicability [105] As apparent from the above description, since the benzylformamidine compounds of the present invention have high ultraviolet light absorption and superior thermal stability, they can be suitably used as ultraviolet light absorbers for plastic products which undergo high-temperature treatment or require superior thermal stability. Par¬ ticularly, the use of the benzylformamidine compounds as ultraviolet light absorbers in the manufacture of plastic products, which undergo high-temperature treatment, allows the plastic products to have high ultraviolet light absorption , thus enhancing the durability of the plastic products. [106] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modi¬ fications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.