Pigment containing polyolefin composition
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a polymer composition. More particularly, the present invention relates to a polymer composition which has high stability to ultraviolet rays and has high fade resistance. 
     2. Description of the Prior Art 
     When a molded product made of a polymer such as a polyolefin or a polystyrene is exposed to light, the mechanical properties and the electrical properties of the product deteriorate. In order to improve the mechanical and electrical properties, various ultraviolet absorbing agents or light stabilizing agents have been incorporated in the polymer. 
     On the other hand, colored compositions composed of a resin and a pigment may fade upon exposure which diminishes the commercial value of the compositions. 
     In practice, when conventional ultraviolet absorbing agents are used for polymers such as benzotriazol type or benzophenone type ultraviolet absorbing agents, the fading problem has been serious in the commercial products, especially those products used outdoors. 
     A need therefore, continues to exist for a method of stabilizing polymer materials from deterioration of their mechanical and electrical properties upon exposure to light. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of the present invention is to provide a pigment containing polymer composition which has high stability to light and high fade resistance. 
     Briefly, this object and other objects of the invention as hereinafter will become more readily apparent can be attained by a polymer containing a quinophthalone pigment and from 0.005-5% by weight of a piperidine or imidazolidine ultraviolet absorbing agent. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the present invention, the polymers which are the base resins of the invention include polyolefins such as polyethylene, polypropylene, polybutadiene, polyisoprene, ethylene-propylene copolymers, ethylenebutene copolymers, ethylene-vinylacetate copolymers, polystyrene, polyvinylchloride, polyacrylonitrile, styrene-acrylonitrile copolymer, ABS resins, acrylic resins, methacrylic resins, polyacetal, polyamides, polycarbonates, epoxy resins, and the like. 
     The quinophthalone type pigments used in the invention can be represented by the formula ##SPC2## 
     Wherein the quinoline ring can have substituent groups and the ring A is a benzene ring or a naphthalene ring which can have substituent groups. The substituent groups on the quinoline ring include halogen, lower alkyl groups, lower alkoxy groups, carboxyl groups, and the substituent groups on the A ring include halogen and --COW wherein W represents hydroxyl, lower alkoxyl or amino. Among the quinophthalone type pigments, the pigments wherein A is a naphthalene ring is especially preferred. 
     The quinophthalone type pigment can be prepared by reacting a quinoline derivative having the formula ##SPC3## 
     wherein the quinoline ring can have suitable substituent groups, with naphthalene-2,3 -dicarboxylic acid, naphthalene-1,2 -dicarboxylic acid or phthalic acid having the formulas ##SPC4## 
     wherein the benzene or naphthalene rings can have substituent groups. More particularly, the quinophthalone type pigments can be represented by the following formulas ##SPC5## ##SPC6## 
     and ##SPC7## 
     wherein X represents hydrogen or halogen, Y represents halogen, Z 1  represents hydrogen, halogen, lower alkyl or lower alkoxy, Z 2  represents hydrogen or halogen, and n represents 0 or an integer of 1-4. The amount of the quinophthalone type pigment used can be usually in the range of 0.01-2% by weight based on the polymer such as a polyolefin. 
     The piperidine type ultraviolet absorbing agents of the present invention include the following derivatives having the formula ##SPC8## 
     wherein R 1  and R 2  are the same or different and each represents an alkyl group or forms a saturated alicyclic ring having 5-7 carbon atoms and sharing a common carbon atom or a ring system having the formula ##SPC9## 
     and n&#39; represents an integer of 1, 2 or 3; 
     R 3  represents, in the case of n&#39; = 1, a monovalent acyl group, 
     an N-substituted carbamoyl group; 
     an N-substituted thiocarbamoyl group, 
     a monovalent group formed by removing one hydroxyl from an oxyacid, an alkyl, a cycloalkyl, an aralkyl or aryl group or a group having the formula ##SPC10## 
     wherein 
     R 1  and R 2  are defined above; 
     R 3  represents, in the case of n&#39; = 2, a diacyl, a dicarbamoyl, a bisthiocarbamoyl, a carbonyl group, or a divalent group formed by removing two hydroxyl groups from an oxyacid, an alkylene, an arylene, or an arylenedialkylene group; 
     R 3  represents, in the case of n&#39; = 3, a triacyl group, a tricarbamoyl group, a tristhiocarbamoyl group, a trivalent group formed by removing three hydroxyl groups from an oxyacid; 
     an alkanetolyl group, an arylinetolyl group or an arylinetolyltrialkylene group. 
     Suitable piperidine derivatives include 4-benzoyloxy-2,2,6,6 -tetramethyl piperidine having the formula ##SPC11## 
     Suitable piperidine derivatives also include piperidine-4-spiro-hydantoin derivatives having the formula ##SPC12## 
     wherein R&#39; 1  and R&#39; 2  are the same or different and each represents an alkyl group or forms a saturated alicyclic ring having 5-7 carbon atoms and sharing a common carbon atom, or a ring having the formula ##SPC13## 
     wherein 
     R 5  and R 6  are the same or different and each represents an alkyl group or forms a saturated alicyclic ring having 5-7 of carbon atoms and sharing a common carbon atom; 
     R&#39; 3  and R 4  are the same or different and each represents hydrogen, an alkyl group, a cycloalkyl group or an aryl group and can have an oxirane oxygen. A preferred piperidine compound is 1,3,8 -triaza-7,7,9,9 -tetramethyl-2,4 -dioxospiro (4.5) decane. 
     Suitable piperidine derivatives further include piperidine derivatives or organic acid salts thereof having the formula ##SPC14## 
     wherein R 1  and R 2  are defined in the formula 1, and R&#34; 3  and R&#39; 4  are the same or different and each represents a cyano group, an aryl group, an alkoxycarbonyl group, an acyl group or a carbamoyl group. A preferred piperidine compound is 4-(α,α-dicyanomethylene)-2,2,6,6 -tetramethyl piperidine. 
     Still further piperidine derivatives or organic acid salts include those having the formula ##SPC15## 
     wherein R 1  and R 2  are as defined in formula (1), and X&#39; represents ##EQU1## A preferred compound is 2,2,2,6 -tetramethyl piperidine. 
     Other piperidine derivatives include iminopiperidine derivatives or organic acid salts thereof having the formula ##SPC16## 
     wherein R 1  and R 2  are as defined in formula (1), and n&#34; represents an integer of 1 or 2, R&#39;&#34; 3  represents, in the case of n&#34; = 1, an alkyl group, an aralkyl group, a cycloalkyl group, an aryl group, an arylamino group, a ureido group, a thioureido group or a group having the formula ##SPC17## 
     wherein R 1  and R 2  are as defined in formula (1), and R&#39;&#34; 3  represents, in the case of n&#34; = 2, a straight chain or a branched chain alkylene group, a cycloalkylene group, an arylene group, and a group having the formula ##SPC18## 
     wherein X&#34; represents --O--, --S--, --S--S--, --NH-- or --(CH 2 )-- m  and m  represents 0 or an integer of 1-6. A preferred compound is 4-n-butylimino-2,2,6,6 -tetramethylpiperidine. 
     The imidazolidine ultraviolet absorbing agents used in the present invention include compounds having the formula ##SPC19## 
     wherein X&#39;&#34; represents oxygen or sulfur and R&#34; 1  and R&#34; 2  are the same or different and each represents hydrogen, alkyl group, a cycloalkyl group, an aryl group or a heterocyclic ring or R&#34; 1  and R&#34; 2  can form a saturated alicyclic ring having 5-7 carbon atoms and sharing a common carbon or a ring having the formula ##SPC20## 
     wherein R&#39; 5  and R&#39; 6  are the same or different and each represents an alkyl group and Y&#39; represents hydrogen or an oxygen radical, and R&#34;&#34; 3 , R&#34; 4  are the same as R&#34; 1  and R&#34; 2 . 
     A preferred compound is cyclohexane-1-spiro-2&#39;-(4&#39;-oxoimidazolidine)-5&#39;-spiro-1&#34;-cyclohexane. 
     The amount of the piperidine or the imidazolidine ultraviolet absorbing agent used is usually in the range of 0.005-5% by weight, preferably 0.01-1% by weight based on the polymer. 
     When the piperidine derivative or the imidazolidine derivative is admixed with the polymer, the conventional method for admixing an ultraviolet absorbing agent can be applied. 
     It is possible to add other stabilizers used for the polymers such as other antioxidants or ultraviolet absorbing agents. 
    
    
     Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. 
     EXAMPLE 1 
     A high density polyethylene (NOVATEC JVO40 Melt Index=5) was admixed with a specific amount of the ultraviolet absorbing agent shown in Table 1, and the mixture was blended by a ribbon blender and was pelletized by an extruder. 
     One hundred parts by weight of the pellets was admixed with 0.8 parts by weight of a yellow pigment composition containing 15% of a quinophalone pigment having the formula ##SPC21## 
     and the mixture was injected by an injection molding machine to form a flat plate test piece. 
     The test piece was irradiated for a specific period in a weather meter manufactured by Toyo Rika Sangyo K. K. (black panel temperature 63°C; humidity 75%). The changes in Hunter whiteness before and after the irradiation were measured by a coloric and gloss meter manufactured by Nippon Denshoku Kogyo K. K. 
     The results are shown in Table 1. 
     
                       TABLE 1                                                     
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Ultraviolet                                                               
         2-hydroxy-4-octoxy                                               
                         4-benzoyloxy-                                    
absorbing                                                                 
         benzophenone    2,2,6,6-tetra-                                   
agent                    methylpiperidine                                 
         0.1%            0.1%                                             
irradiation                                                               
period   L      a      b    W    L    a    b    W                         
______________________________________                                    
0        74.8   9.6    41.6 50.5 72.8 11.4 41.6 49.1                      
 750 hrs.                                                                 
         78.7   9.3    30.8 61.4 75.2 12.0 36.8 54.0                      
1000 hrs.                                                                 
         78.9   7.9    28.6 63.6 75.5 11.0 33.9 56.7                      
1250 hrs.                                                                 
         79.7   7.8    26.7 65.6 76.2 10.9 31.7 58.9                      
1500 hrs.                                                                 
         80.2   7.5    25.6 66.7 76.4 10.7 30.7 59.9                      
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     It is clear from Table 1, that the Hunter whiteness values, especially the difference (Δb) before and after irradiation, which measures the amount of fading, in the case of the addition of 4-benzoyloxy-2,2,6,6 -tetramethylpiperidine (Δb = -10.9 for 1500 hrs.) was remarkably superior than the Δb value of benzophenone (Δ = -16.0 for 1500 hrs.). 
     EXAMPLE 2 
     The process of Example 1 was repeated except that a yellow pigment composition containing 10% of the following quinophthalone pigment having the formula ##SPC22## 
     and the ultraviolet absorbing agents shown in Table 2 was used. 
     The changes in the Hunter whiteness values were measured. 
     The results are shown in Table 2. 
     
                       TABLE 2                                                     
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Ultraviolet absorbing agent                                               
                   Amount                                                 
______________________________________                                    
(1)   2-(2&#39;-hydroxy-3&#39;, 5&#39;-                                               
      di-t-butylphenyl)-5-                                                
                       0.03%      0.065%                                  
      chlorobenzotriazol                                                  
(2)   4-benzoyloxy-2,2, 6,                                                
      6-tetramethylpiperidine                                             
                       0.03%      0.065%                                  
Fade  250 hrs.         -1.6       -1.3                                    
(Δb)                                                                
      500 hrs.         -3.0       -2.4                                    
      710 hrs.         -4.2       -3.2                                    
      900 hrs.         -5.7       -4.2                                    
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     EXAMPLE 3 
     The process of Example 2 was repeated except that the ultraviolet absorbing agents shown in Table 3 were used. 
     The changes in Hunter whiteness values were measured. 
     The results are shown in Table 3. 
     
                                           TABLE 3                                 
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Ultraviolet absorbing agent                                               
                        Amount                                            
__________________________________________________________________________
(1)                                                                       
   1,3,8-triaza-7,7,9,9-                                                  
   pentamethyl-2,4-dioxo-                                                 
                  0.1%  --    --    --                                    
   spiro[4.5]decane                                                       
(2)                                                                       
   1,3,8-triaza-3-(2&#39;,3&#39;                                                  
   epoxy-propyl)-7,7,8,9,9-                                               
                  --    0.1%  --    --                                    
   pentamethyl-2,4-dioxo-                                                 
   spiro[4.5]decane                                                       
(3)                                                                       
   1,3,8-triaza-3-octyl-7,7                                               
   9,9-tetramethyl-8-benzyl-                                              
                  --    --    0.1%  --                                    
   2,4-dioxo-spiro[4.5]decane                                             
(4)                                                                       
   cyclohexane-1-spiro-2&#39;-                                                
   (4-oxoimidazolidine)-5&#39;-                                               
   spiro-1&#34;-cyclohexane                                                   
                  --    --    --    0.1%                                  
(5)                                                                       
   2-(2&#39;-hydroxy-3&#39;,5&#39;-                                                   
   di-t-butyphenyl)-5-                                                    
   chlorobenzotriazol                                                     
                  0.1%  0.1%  0.1%  0.1%                                  
Fade                                                                      
   (Δb)                                                             
       250  hrs.  -2.2  -1.9  -2.3  -1.9                                  
       500  hrs.  -5.3  -4.5  -5.5  -4.5                                  
       710  hrs.  -8.5  -7.3  -8.8  -7.3                                  
       900  hrs.  -11.0 -9.5  -11.5 -9.5                                  
       1150 hrs.  -13.6 -11.6 -14.0 -11.6                                 
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     EXAMPLE 4 
     The process of Example 1 was repeated except that the following quinophthalone pigments (A)-(E) were used. 
     The changes in Hunter whiteness values before and after irradiation were measured. 
     The fade resistance effects were the same with those of Example 1. ##SPC23## 
     EXAMPLE 5 
     A quinophthalone pigment having the formula ##SPC24## 
     and the ultraviolet absorbing agent 1,3,8-triaza-7,7,9,9-tetramethyl-3-octyl-2,4-dioxo-spiro[4.5] decane were admixed with polystyrene pellets (DIAREX HF 77) acrylonitrile-styrene copolymer pellets (SANREX SAN-C) and ABS resin pellets (TUFREX 410). 
     The mixture were respectively treated by the process of Example 1. The changes in the Hunter whiteness values before and after irradiation were measured. Fade resistance effects as found in Example 1 were obtained. 
     Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.