Abstract:
The storage stability of impure hydroxybenzophenones is improved by the addition thereto of an organic phosphite or organic phosphonite.

Description:
FIELD OF INVENTION 
     This invention relates to hydroxybenzophenones useful as stabilizers for organic polymers. Particularly this invention relates to hydroxybenzophenones having improved storage stability. More particularly this invention relates to combinations of an impure hydroxybenzophenone and an organic phosphite or organic phosphonite compound. 
     BACKGROUND 
     Hydroxybenzophenones have been known in the art for quite sometime, particularly with respect to their utility as stabilizers for organic polymers. More particularly substituted and unsubstituted 2-hydroxybenzophenones have been widely used as UV stabilizers for polyolefins. Thus they are of significant commercial interest. The manufacture of substituted and unsubstituted 2-hydroxybenzophenones, particularly by commercial processes, yields products which very often contain impurities. These impurities contribute color to the product and/or cause the product to be color unstable upon standing, particularly when exposed to light and air. Color changes and/or darkening sometimes occur in a matter of a few hours at room temperature. Such color changes, which are often caused by a small percentage of impurity which is difficult to remove, reduce the commercial acceptance of such substituted or unsubstituted 2-hydroxybenzophenones and thereby impedes the commercial use of these materials. To, at least in part, overcome these color and color instability problems the prior art resorted to physical means to highly purify the impure substituted and unsubstituted hydroxybenzophenones. These physical means have added steps and cost to the preparation of the 2-hydroxybenzophenones and in some cases caused decreased yields. 
     Since hydroxybenzophenones are valuable UV stabilizers in commerce, it is highly desirable to overcome these color and color instability problems, particularly without burdening the process and significantly increasing the cost of making them. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the color instability of impure hydroxybenzophenones. 
     Another object of this invention is to provide color stable substituted and unsubstituted hydroxybenzophenones. 
     A still further object of this invention is to provide a method for stabilizing substituted and unsubstituted hydroxybenzophenones against color change upon standing. 
     Other objects of this invention will become apparent from the following description. 
     It has now been found that the above objects and others can be realized by a polymer free composition comprising a substituted or unsubstituted 2-hydroxybenzophenone and an organic phosphorus compound selected from the group consisting of secondary organic phosphite, tertiary organic phosphite or organic phosphonite. Further, there has now been found a method of stabilizing substituted and unsubstituted 2-hydroxybenzophenones against color change during storage comprising the step of adding to said 2-hydroxybenzophenone a secondary organic phosphite or a tertiary organic phosphite or an organic phosphonite. 
     DESCRIPTION OF THE INVENTION 
     In accordance with this invention there are provided polymer free substituted and unsubstituted 2-hydroxybenzophenone compositions, resistant to color change upon standing, comprising a color unstable substituted or unsubstituted 2-hydroxybenzophenone, and an organic phosphorus compound selected from the group consisting of secondary organic phosphite, tertiary organic phosphite or an organic phosphonite. The substituted and unsubstituted 2-hydroxybenzophenones in accordance with this invention can be given by the following formula. ##STR1## wherein: R 1  and R 4  are the same or different and are selected from the group consisting of (1) hydrogen and (2) unsubstituted and substituted alkyl, aryl, alkaryl, aralkyl, alkenyl or cycloalkyl group wherein the substituent is halogen, 
     R 2  and R 3  are the same or different and are selected from the group consisting of R 1 , Br, Cl and alkoxy, 
     a is 0, 1 or 2, 
     b is 0, 1 or 2, 
     c is 0, 1 or 2 
     d is 0, 1 or 2, 
     a+b is 0 to 3, 
     c+d is 0 to 3 and 
     a+b+c+d is 0 to 4. 
     Secondary and tertiary organic phosphites according to this invention are organic phosphites having a trivalent phosphorus atom and two or three P-O-C linkages (i.e. phosphorus-oxygen-carbon linkage) which may, for example, be described by the formulae ##STR2## wherein R is hydrogen, an aliphatic (preferably C 8  to C 20  alkyl), aromatic (preferably phenyl), alkyl substituted aromatic (preferably C 7  to C 18 ), aryl substituted aliphatic (preferably C 7  to C 18 ), cycloaliphatic (preferably C 6 ), diphenyl or phenyl-alkylene-phenyl group having a valence equal to n, R&#39; an alkyl (preferably C 8  to C 20 ), hydroxyalkyl, aryl (preferably phenyl), aralkyl (preferably C 7  to C 18 ), alkaryl (preferably C 7  to C 18 ), alkenyl or cycloalkyl (preferably C 6 ) group, or R&#39; groups and optionally the R group together with the oxygen atoms and phosphorus atom of the phosphite join to form a heterocyclic ring structure, R&#34; is a divalent or tetravalent aliphatic, aromatic or cycloaliphatic radical, R&#39;&#34; is an alkylene group optionally containing ether linkages, m is 1 or 2, n is an integer from 1 to 6 and p is an integer from 1 to 1000. The organic phosphonites according to this invention may be, for example, described by the formulae ##STR3## wherein R 5  is hydrogen, or an aliphatic, aromatic, alkyl substituted aromatic, aryl substituted aliphatic or cycloaliphatic radical having a valence of q, R 6  is an alkyl, aryl, aralkyl, alkaryl, cycloalkyl or alkenyl group or the R 6  groups together with the oxygen atoms and the phosphorus atom may join to form a heterocyclic ring, R 7  is an alkyl, aryl, aralkyl, alkaryl, cycloalkyl or alkenyl group, R 8  is an alkylene group optionally containing ether linkages, q is an integer from 1 to 6 and x is an integer from 1 to 1000. The preferred secondary organic phosphites, tertiary organic phosphites and organic phosphonites usable in this invention are those having low volatility, especially at elevated temperatures. 
     This invention provides useful improved polymer free 2-hydroxybenzophenone compositions which are resistant to color change on standing, particularly upon standing exposed to light and air. As one embodiment of this invention there is provided a polymer free 2-hydroxybenzophenone composition comprising (a) a substituted or unsubstituted 2-hydroxybenzophenone which is color unstable upon standing and (b) a secondary or tertiary organic phosphite. According to another embodiment of this invention, there is provided a polymer free 2-hydroxybenzophenone composition comprising (a) a substituted or unsubstituted 2-hydroxybenzophenone which is color unstable upon standing and (b) an organic phosphonite. In a further embodiment of this invention polymer free 2-hydroxybenzophenone compositions are provided comprising (a) a substituted or unsubstituted 2-hydroxybenzophenone which is color unstable upon standing and (b) an organic phosphite according to formula (I) above. Other embodiments of this invention include polymer free 2-hydroxybenzophenone compositions comprising a substituted or unsubstituted 2-hydroxybenzophenone which is color unstable upon standing and an organic phosphite according to formula II or III above or an organic phosphonite according to formula IV or V above. 
     The polymer free 2-hydroxybenzophenone compositions of this invention are useful as stabilizers (e.g. heat and light stabilizers for polyolefins (e.g. polyethylene and polypropylene or their copolymers). In the context of this disclosure and of the claims of this invention the phrase polymer free 2-hydroxybenzophenone compositions shall mean 2-hydroxybenzophenone compositions of this invention which do not contain a polymer for which substituted and unsubstituted 2-hydroxybenzophenones and/or secondary organic phosphites, tertiary organic phosphites and organic phosphonites are stabilizers. 
     In the practice of this invention the secondary organic phosphite, tertiary organic phosphite or the organic phosphonite may be combined with the 2-hydroxybenzophenone over a wide concentration range. Thus, for example, as little as 0.01 part and as high as 90 parts of the secondary organic phosphite, tertiary organic phosphite or the organic phosphonite may be present in 100 parts total of the combination of the substituted or unsubstituted 2-hydroxybenzophenone and the secondary organic phosphite or tertiary organic phosphite or the organic phosphonite. The amount of the secondary organic phosphite, tertiary organic phosphite or the organic phosphonite present in the mixture will depend on a number factors including the composition of the substituted or unsubstituted 2-hydroxybenzophenone, the color instability of the substituted or unsubstituted 2-hydroxybenzophenone, the nature of the secondary organic phosphite, tertiary organic phosphite or the organic phosphonite, the intended use of the combination, compatibility and costs. Preferably, the amount of the secondary organic phosphite, tertiary organic phosphite or organic phosphonite in the compositions of this invention ranges from about 0.1 to about 25 percent, more preferably from about  0.5 to about 10 percent, based on the total weight of the combination of the secondary organic phosphite or tertiary organic phosphite or the organic phosphonite and the substituted or unsubstituted 2-hydroxybenzophenone. The organic phosphites are preferred, tertiary organic phosphites more preferred and aliphatic tertiary organic phosphites still more preferred in the practice of this invention. Combinations of color unstable unsubstituted or substituted 2-hydroxybenzophenone and an aliphatic tertiary organic phosphite having 8 to 18 carbon atoms in the aliphatic group are especially preferred. 
     Substituted and unsubstituted 2-hydroxybenzophenones usable in the practice of this invention include, but are not limited to, color unstable: 
     2-hydroxybenzophenone 
     2-hydroxy-4-methoxybenzophenone 
     2-hydroxy-4-hexyloxybenzophenone 
     2-hydroxy-4-heptyloxybenzophenone 
     2-hydroxy-4-octyloxybenzophenone 
     2-hydroxy-4-(2-ethyhexyloxy)benzophenone 
     2-hydroxy-4-benzyloxybenzophenone 
     2-hydroxy-4-octadecyloxybenzophenone 
     2-hydroxy-4-methylbenzophenone 
     2-hydroxy-4-decylbenzophenone 
     2-hydroxy-4-bromobenzophenone 
     2-hydroxy-4-chlorobenzophenone 
     2-hydroxy-4-iodobenzophenone 
     2-hydroxy-4-methoxy-4&#39;-tertiary butylbenzophenone 
     2-hydroxy-4-benzyloxy-4&#39;-octylbenzophenone 
     2-hydroxy-4-decyloxy-4&#39;-butylbenzophenone 
     2-hydroxy-4-(pentachlorobenzoyloxy) benzophenone 
     2-hydroxy-4-octylbenzophenone 
     2-hydroxy-4-isooctylbenzophenone 
     2-hydroxy-4-isooctyloxybenzophenone 
     2-hydroxy-4,4&#39;-dimethoxybenzophenone 
     2-hydroxy-4,4&#39;-dimethylbenzophenone 
     2-hydroxy-4,5-dimethylbenzophenone 
     2-hydroxy-4-ethyl-3&#39;-chlorobenzophenone 
     2-hydroxy-4-methoxy-4&#39;-octoxybenzophenone 
     2,2&#39;-dihydroxybenzophenone 
     2,2&#39;-dihydroxy-4-methylbenzophenone 
     2,2&#39;-dihydroxy-4&#39;-tertiary butylbenzophenone 
     2,2&#39;-dihydroxy-4,4&#39;-dimethoxybenzophenone 
     2,2&#39;-dihydroxy-4-octoxybenzophenone 
     2,2&#39;-dihydroxy-4-isooctoxybenzophenone 
     2,2&#39;-dihydroxy-4-benzoxybenzophenone 
     2,2&#39;-dihydroxy-4-octoxy-4&#39;-methoxybenzophenone 
     2,2&#39;-dihydroxy-4-4&#39;-dioctoxybenzophenone 
     2,2&#39;-dihydroxy-4-chlorobenzophenone 
     2,4-dihydroxybenzophenone 
     2,2&#39;,4-trihydroxybenzophenone 
     As secondary and tertiary organic phosphites usable in the practice of this invention there includes, but not limited to, for example: 
     triphenyl phosphite 
     tricyclohexyl phosphite 
     triethyl phosphite 
     trioctyl phosphite 
     trihexyl phosphite 
     tridodecyl phosphite 
     trioctadecyl phosphite 
     triisopropyl phosphite 
     tri-tertiary butyl phosphite 
     tri 2-ethylhexyl phosphite 
     tricresyl phosphite 
     tri (dimethylphenyl)phosphite 
     tri (t-octylphenyl) phosphite 
     tri (nonylphenyl) phosphite 
     tri docosanyl phosphite 
     monophenyl dioctyl phosphite 
     tri benzyl phosphite 
     monobutyl-diphenyl phosphite 
     mono-nonylphenyl-dioctyl phosphite 
     monohexyl diisopropyl phosphite 
     cycohexyl-dioctadecyl phosphite 
     diphenyl-neopentyl diphosphite 
     diisooctyl-octylphenyl phosphite 
     tetrakis (nonylphenyl) propylene glycol diphosphite 
     heptakis (dipropylene glycol) triphosphite 
     poly (dipropylene glycol) phenyl phosphite 
     distearyl pentaerythritol diphosphite 
     neopentyl diphosphite 
     dilauryl hydrogen phosphite 
     dioctyl hydrogen phosphite 
     dioctadecyl hydrogen phosphite 
     trimethylol propane phosphite 
     2,2-dimethyl-1,3-propylene lauryl phosphite 
     Illustrative of the organic phosphonites that may be used in the practice of this invention are alkyl, aryl, aralkyl, alkaryl, cycloalkyl and heterocyclic phosphonites--examples of which include, but are not limited to, 
     phenyl diethyl phosphonite 
     octyl dibutyl phosphonite 
     decyl diisopropyl phosphonite 
     hexyl di-tertiary butyl phosphonite 
     dodecyl dioctyl phosphonite 
     cyclohexyl dioctadecyl phosphonite 
     lauryl diphenyl phosphonite 
     phenyl dicyclohexyl phosphonite 
     nonylphenyl di-nonylphenyl phosphonite 
     stearyl di-benzyl phosphonite 
     dioctyl neopentyl diphosphonite 
     Organic phosphonites also usable in the practice of this invention include those phosphonites disclosed in U.S. Pat. Nos. 3,928,510, 3,962,175 and 3,978,020 the entire disclosures of which are incorporated herein by reference. 
     Methods well known in the art may be used to make the combination of the color unstable substituted or unsubstituted 2-hydroxybenzophenone and the secondary organic phosphite or tertiary organic phosphite or the organic phosphonite according to this invention. 
     
                       TABLE I______________________________________                                  Trans-Ex-                     Per-   Percent missionample Phosphite         cent   Before  After______________________________________1     none              0      81.3    22.82     trilauryl phosphite                   0.5    82.0    64.33     &#34;                 5.0    85.1    85.94     &#34;                 25.0   94.3    95.05     &#34;                 50.0   98.4    98.26     phenyldidecyl phosphite                   5.0    83.6    80.97     phenyldidecyl phosphite                   25.0   92.8    93.18     neopentyl diphosphite                   5.0    84.0    83.99     triphenyl phosphite                   5.0    81.6    52.010    tris-nonylphenyl phosphite                   5.0    80.9    55.811    diphenyldecyl phosphite                   5.0    82.3    74.112    tricyclohexyl phosphite                   5.0    81.9    80.013    tributyl phosphite                   5.0    83.3    82.914    trioctadecyl phosphite                   5.0    82.6    83.315    &#34;                 0.5    80.3    61.116    &#34;                 25.0   92.1    91.417    &#34;                 70.0   99.1    99.318    tridocosanyl phosphite                   5.0    83.1    82.619    phenylneopentyl phosphite                   5.0    80.9    76.620    diisooctyloctylphenyl phosphite         5.0    81.7    73.421    tetrakis(nonylphenyl) propyleneglycol diphosphite                   5.0    82.3    74.022    heptakis(dipropyleneglycol)- triphosphite      5.0    83.0    79.923    poly(dipropyleneglycol) phenyl phosphite  5.0    81.1    78.8______________________________________ 
    
     Thus the color unstable substituted or unsubstituted 2-hydroxybenzophenone may be mixed with the secondary or tertiary organic phosphite or organic phosphonite or conversely the secondary or tertiary organic phosphite or organic phosphonite may be mixed with the color unstable substituted or unsubstituted 2-hydroxybenzophenone at reduced, room or elevated temperatures by wet or dry techniques using mixers well known in the art. Solvents may be employed in making the combinations. 
    
    
     This invention is further described with respect to specific embodiments by the following non-limiting examples. 
     EXAMPLES 1-29 
     Test mixtures of 2-hydroxy-4-isooctoxybenzophenone with various phosphites or a phosphonite were placed in 2 oz. square bottles (clear glass) and exposed to indirect sunlight for 5 days. The color was measured before and after exposure by diluting a portion of the mixture with toluene (90% toluene, 10% test mixture) and measuring the transmission at 480 mu on a Coleman Spectrophotometer (Model 44). The test results using several different phosphites and one phosphonite are shown in Table I. 
     
         ______________________________________                                  Trans-Ex-                     Per-   Percent missionample Phosphite         cent   Before  After______________________________________24    distearylpentaerythritol diphosphite       5.0    82.9    84.625    distearylpentaerythritol diphosphite       0.5    81.3    66.126    distearylpentaerythritol diphosphite       10.0   87.1    88.027    phosphonite P-EPQ**                   5.0    84.2    72.328    dilauryl phosphite                   25.0   93.8    94.129    distearyl phosphite                   25.0   93.9    93.830    dioctyl phosphite 25.0   92.7    95.1______________________________________ **Sold by Sandox Colors &amp; Chemicals of Hanover, New Jersey, and has the following structure: ##STR4## 
    
     Although this invention has been described with respect to various embodiments, it is to be recognized that one skilled in the art may, from the above teachings, practice further embodiments without departing from the spirit and scope of the invention described above and claimed in the following claims.