1,1-Bis(tert-butylperoxy)cyclododecane
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to 1,1-bis(tert-butylperoxy)cyclododecane, a novel solid and stable compound, and its use as a crosslinking or curing agent. 
     2. Description of the Prior Art 
     It has been disclosed that bisperoxyketals can be used, together with dialkylperoxides, e.g., dicumyl peroxide, for crosslinking or curing natural rubber, synthetic rubber and ethylene homo-polymers and copolymers. Bisperoxyketals can lower the crosslinking temperature, since the thermal decomposition temperature of bisperoxyketals is lower than that of dialkyl peroxides. 
     U.S. Pat. No. 2,455,569 discloses an extensive use of bisperoxyketals and bisperoxyacetals. However, it does not make reference to their use as crosslinking catalysts. 
     German Pat. No. 945,187 discloses the use of 2,2-bis(tert-butylperoxy)butane and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane as catalysts for a rubber vulcanizing process. 
     U.S. Pat. No. 3,296,184 discloses the combined use of 2,2-bis(tert-butylperoxy)butane, 1,1,7,7-tetra(tert-(butylperoxy)cyclododecane and sulfur for crosslinking olefin homo-polymers and copolymers. 
     British Pat. No. 1,044,010 discloses the use of 2,2-bis(4,4-di-tert-butylperoxy cyclohexyl)propane as a catalyst for crosslinking. This compound has about the same thermal decomposition rate as that of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane. 
     U.S. Pat. No. 3,433,825 discloses esters of 4,4-bis(tert-butylperoxy)pentanoic acid. These peroxides have a thermal decomposition rate slower than that of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and therefore can be used without scorching or premature cure, according to the disclosure. 
     U.S. Pat. No. 3,686,102 discloses 2,2-bis(tert-butylperoxy)-4-methylpentane as a bisperoxyketal which can be used at a temperature between that for 1,1-bis(tert-butylperoxy)-3,3,5-trimethylhexane and that for n-butyl-4,4-bis(tert-butylperoxy)valerate. However, this compound has a relatively low molecular weight, and therefore is volatilized in a crosslinking process. Accordingly, only 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcycohexane and n-butyl-4,4-bis(tert-butylperoxy) valerate are sold in the market as crosslinking catalysts. 
     German Pat. Application No. 2,317,965 laid open to public inspection discloses bis(tert-octylperoxy)alkane. However, this compound is faster in thermal decomposition rate than tert-butyl derivatives, and therefore is not suitable for use as a crosslinking catalyst. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a crosslinking agent which gives a desirable crosslinking rate to ethylene homopolymers and copolymers. 
     It is another object of the present invention to provide a crosslinking agent which is easy to handle and gives no odor to crosslinked materials. 
     It is still another object of the present invention to provide a crosslinking agent which has a low volatility and furnishes the crosslinking process with an excellent operational environment. 
     The inventors of the present invention reacted cyclododecanone with tert-butylhydroperoxide in an organic solvent using a catalyst such as sulfuric acid, hydrochloric acid, calcium chloride - hydrochloric acid, and cation exchange resin, and thereby synthesized a novel compound having the formula ##STR2## As the organic solvent, aromatic hydrocarbons such as toluene and benzene, and aliphatic hydrocarbons such as n-hexane and cyclohexane are preferably used. The amount of the catalyst is, for instance, when the catalyst is 70 wt.% sulfuric acid, from 140 to 400 g, preferably 200 to 300 g per one mole of cyclododecanone. 
     The results of the infrared spectrophotometry of this novel compound showed that no absorption of hydroxyl group existed, but an absorption peculiar to peroxides was recognized at 875 cm -1 . The results of the nuclear magnetic spectrum analysis showed that absorptions of 1.30 PPM (18 H) and 1.45 PPM (22 H) were recognized. The melting point of this novel compound was found to be 67° to 68° C, and the elementary analysis of the novel compound showed that the novel compound contained 69.67 % carbon, 11.86% hydrogen and 18.47% oxygen. 
     The present invention was made on the basis of the knowledge that this novel compound, 1,1 bis(tert-butylperoxy)cyclododecane, has excellent properties as a crosslinking agent as shown in the following: 
     (1) The crosslinking rate of this novel compound is greater than that of n-butyl 4,4-bis(tert-butylperoxy)valerate and is lower than that of 1,1-bis(tert-butylperoxy)-3,3,5-trimethyl cyclohexane. Therefore, scorching does not occur during the mixing operation (at temperatures of 110° to 130° C) and the crosslinking rate at the cure temperature (140° to 150° C) is rapid. 
     (2) The odor of the crosslinked composition generated by decomposition of the organic peroxide is weaker than that of n-butyl 4,4-bis(tert-butylperoxy) valerate and is about as strong as that of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane. 
     (3) Because this novel compound is low in volatility, the loss of the peroxide during the mixing process is small and, consequently, the operational environment is improved. 
     (4) Because this novel compound has its melting point of 67° to 68° C, it can be mixed with carriers such as calcium carbonate and calcium silicate in any proportion without separation, and therefore it is easily to handle. 
     (5) The novel compound is a stable peroxide in its pure state, and therefore is easy to handle. 
     Polymeric materials that can be crosslinked by the crosslinking agent according to the present invention include ethylene homopolymers, ethyl-vinylacetate copolymers, ethylene-propylene rubbers, natural rubber, etc. 
     The crosslinking agent according to the present invention can be used alone, as a matter of course. In addition, it can be used in the state of an inseparable mixture which are produced by mixing it with carriers such as calcium carbonate and calcium silicte in any proportion, since it is solid at room temperature. 
     The crosslinking agent according to the present invention may be used in combination with suitable crosslinking coagents such as ethyleneglycoldimethylacrylate and sulfur in a crosslinking process thereby improving the physical properties of the crosslinked materials produced. 
     Besides, the crosslinking agent according to the present invention may be used together with ordinary fillers such as carbon black, zinc white and manganese dioxide. 
     The crosslinking process according to the present invention is carried out at pressures of 50 to 200 kg/cm 2 , at temperatures of 100° to 200° C, preferably at 140° to 170° C, and for 1 to 60 minutes, preferably for 3 to 30 minutes. 
     The amount of the crosslinking agent to be added is 0.3 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of polymeric materials. 
     PREFERRED EMBODIMENTS OF THE INVENTION 
     EXAMPLE 1 
     Production of 1,1-bis(tert-butylperoxy)cyclododecane: 
     Into a four openings flask equipped with a mechanical stirrer, 70 ml of n-hexane, 27.8 g (0.25 mole) of tert-butylhydroperoxide (for industrial use, purity: 81 %, and 18.2 g (0.1 mole) of cyclododecanone were introduced. Then, the solution was cooled to 0° C, and 30g of 70% sulfuric acid were added little by little with stirring. After all the above reactants were added, the reaction mixture was stirred at 0° C for 3 hours. The reaction product mixture was then separated and the organic layer thereof was washed with water until it became neutralized. After the resulting product was dried using anhydrous magnesium sulfate, n-hexane was distilled away therefrom at temperatures of 30° to 40° C under a reduced pressure of 20 mmHg to obtain a white and solid raw product. 
     In order to remove non-reacted components and impurities the raw product was washed twice with an aqueous solution of 80 % methanol and was then washed with water. It was then dried to obtain 32.1 g of a white and solid refined product. Iodometric titration showed that the purity of the refined product was 98.6 %, and the yield with respect to cyclododecanone was 92 %. Besides, it showed the following properties: 
     Melting point: 67° - 68° C 
     
         ______________________________________                                    
Composition (according to elementary analysis):                           
         Measured value                                                   
                    Theoretical value                                     
______________________________________                                    
C(%)       69.69        69.72                                             
H(%)       11.86        11.70                                             
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     EXAMPLE 2 
     Properties of 1,1-bis(tert-butylperoxy) cyclododecane and peroxides similar thereto: 
     In the same manner as in the case of Example 1, cyclododecanone was made to react with each of tert-amylhydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide and tert-hexylhydroperoxide to synthesize the corresponding bis(tert-alkylperoxy)cyclododecanes. 
     The thermal decomposition rates of the peroxide according to the present invention, peroxides similar thereto, and publicly known peroxides were measured in benzene. The results are shown in Table 1. 
     
                       Table 1.                                                    
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Thermal Decomposition Rate                                                
Solvent: Benzene                                                          
Initial concentration: 0.05 mole/1 (0.1 mole/1 for                        
dicumylperoxide)                                                          
              Melting                                                     
              point  Half life(hours)                                     
Peroxide        (° C)                                              
                         90° C                                     
                                 100° C                            
                                       110° C                      
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1,1-bis(tert-butylperoxy)-                                                
                67 - 68  20.9    5.6   --                                 
cyclododecane                                                             
1,1-bis(tert-amylperoxy)-                                                 
                15 - 16  10.4    3.0   --                                 
cyclododecane                                                             
1,1-bis(tert-hexylperoxy)-                                                
                35 - 36  11.3    3.1   --                                 
cyclododecane                                                             
1,1-bis(1,1,3,3-tetramethyl-                                              
                          3.5    --    --                                 
butylperoxy)cyclododecane                                                 
1,1-bis(tert-butylperoxy)-                                                
                         10.2    3.0   0.9                                
3,3,5-trimethylcyclohexane                                                
n-butyl 4,4-bis(tert-            15.9  5.6                                
butylperoxy) valerate                                                     
Dicumylperoxide                        25.6                               
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     The above results show that the thermal decomposition rate of the peroxide according to the present invention is lowest among those of the similar cyclododecane peroxides, and is lower than that of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and is greater than those of n-butyl 4,4-bis(tert-butylperoxy) valerate and dicumylperoxide. 
     These facts suggest that the peroxide according to the present invention involves no scorching in the mixing process and achieves a high crosslinking rate in the crosslinking process. 
     Then, tests were conducted on the safety degrees of the peroxide according to the present invention, cyclododecane peroxides similar thereto, and publicly-known peroxides. The results are shown in Table 2. 
     
                       Table 2.                                                    
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Safety Degree                                                             
               Rapid heat                                                 
               test      Ballistic Pressure                               
               Foaming   motar test                                       
                                   vessel test                            
               decomp.   As against                                       
                                   Orifice dia.                           
Peroxide       temp. (° C)                                         
                         TNT (%)   (mm)                                   
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1,1-bis(tert-butylperoxy)-                                                
               119       0.63      3.5 or less                            
cyclododecane                                                             
1,1-bis(tert-amylproxy)-                                                  
               115       0.61      3.5 or less                            
cyclododecane                                                             
1,1-bis(tert-hexylperoxy)-                                                
               120       0.60      3.5 or less                            
cyclododecane                                                             
1,1-bis(1,1,3,3-tetramethyl-                                              
               102       0.61      3.5 or less                            
butylperoxy)cyclododecane                                                 
1,1-bis(tert-butylperoxy)-                                                
               114       10.2      4.9                                    
3,3,5-trimethylcyclohexane                                                
n-butyl 4,4-bis(tert-butyl-                                               
               129       0.81      3.5                                    
peroxy) valerate                                                          
Dicumylperoxide                                                           
               130       0.50      3.5 or less                            
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     The methods of the above tests conform to &#34;Safety Engineering&#34;, Section 4(2), Page 131, written by Kitagawa et al. and published in 1965. 
     The above results show that the peroxide according to the present invention is stable. 
     EXAMPLE III 
     Crosslinking of EPDM: 
     Crosslinking tests of EPDM (Produced by Sumitomo Chemical Co., Ltd, Trade Name: Esprene) were conducted using the peroxide according to the present invention, cyclododecane peroxides similar thereto, and publicly-known peroxides. 
     Each peroxide was previously mixed with calcium carbonate, which functioned as a carrier, until the concentration of the peroxide became 40% by weight. 
     The mixing process was carried out by a roll mixer. Then, the crosslinking process was carried out in a press at a pressure of 150 kg/cm 2 , at a temperature of 150° C (160° C for dicumylperoxide), and for 10 to 40 minutes. 
     Table 3 shows the compositions of polymer mixtures, and Table 4 shows the physical properties of the cross-linked materials produced. 
     
                                           Table 3.                                
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Compositions of Polymer Mixtures                                          
(Parts by Weight)                                                         
Specimen No.    1   2   3   4   5   6   7   8                             
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EPDM (Esprene 502)                                                        
                100 100 100 100 100 100 100 100                           
Stearic acid    1   1   1   1   1   1   1   1                             
Zinc white      5   5   5   5   5   5   5   5                             
HAF carbon black                                                          
                40  40  40  40  40  40  40  40                            
1,1-bis(tert-butylperoxy)-                                                
                8.60                                                      
                    8.60                                                  
                        8.60                                              
                            --  --  --  --  --                            
cyclododecane                                                             
1,1-bis(tert-amylperoxy)-                                                 
                --  --  --   9.30                                         
                                --  --  --  --                            
cyclododecane                                                             
1,1-bis(tert-hexylperoxy)-                                                
                --  --  --  --  10.0                                      
                                    --  --  --                            
cyclododecane                                                             
1,1-bis(tert-butylperoxy)-                                                
                --  --  --  --  --   7.55                                 
                                        --  --                            
3,3,5-trimethylcyclohexane                                                
n-butyl 4,4-bis(tert-butyl-                                               
                --  --  --  --  --   8.35                                 
                                        --                                
peroxy) valerate                                                          
Dicumyl peroxide                                                          
                --  --  --  --  --  --   6.75                             
Sulphur         --    0.32                                                
                        --  --  --  --  --  --                            
Ethyleneglycol-di-methacrylate                                            
                --  --  3.0 --  --  --  --  --                            
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                                           Table 4.                                
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Physical Properties of Crosslinked Materials                              
Specimen No.  1   2   3   4   5   6   7   8                               
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Curing temperature (° C)                                           
              150 150 150 150 150 150 150 160                             
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Tensile Curing                                                            
            10                                                            
              200 242 209 130 160 209 180 200                             
strength                                                                  
        time                                                              
            20                                                            
              201 242 203 145 165 202 197 210                             
(kg/cm.sup.2)                                                             
        (min.)                                                            
            30                                                            
              196 244 196 150 170 203 210 220                             
            40                                                            
              198 244 196 155 170 200 210 212                             
Elongation                                                                
        Curing                                                            
            10                                                            
              560 570 330 760 740 540 540 570                             
(%)     time                                                              
            20                                                            
              550 580 330 740 740 510 400 450                             
        (min.)                                                            
            30                                                            
              560 570 310 740 720 510 400 400                             
            40                                                            
              560 570 310 730 750 510 400 420                             
100% modulus                                                              
        Curing                                                            
            10                                                            
              16  22  32  14  14  17  17  15                              
(kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              18  22  32  14  14  16  19  18                              
        (min.)                                                            
            30                                                            
              17  21  32  15  14  16  18  19                              
            40                                                            
              18  21  33  15  14  17  19  18                              
200% modulus                                                              
        Curing                                                            
            10                                                            
              30  44  85  18  21  32  32  31                              
(kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              31  42  83  19  21  32  34  46                              
        (min.)                                                            
            30                                                            
              34  43  84  20  22  34  35  50                              
            40                                                            
              33  41  87  21  21  34  35  48                              
300% modulus                                                              
        Curing                                                            
            10                                                            
              67  85  181 30  35  67  64  65                              
(kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              74  83  175 32  37  74  75  105                             
        (min.)                                                            
            30                                                            
              72  84  178 33  37  74  76  114                             
            40                                                            
              71  87  181 35  37  73  78  113                             
Spring  Curing                                                            
            10                                                            
              61  65  72  57  59  61  61  60                              
hardness                                                                  
        time                                                              
            20                                                            
              61  66  71  58  58  61  62  61                              
(Hs)    (min.)                                                            
            30                                                            
              61  66  72  58  58  62  64  62                              
            40                                                            
              62  65  70  59  59  62  62  63                              
Odor          None                                                        
                  None                                                    
                      None                                                
                          None                                            
                              None                                        
                                  None                                    
                                      Slight                              
                                          Con-                            
                                          sider-                          
                                          able                            
Blooming      None                                                        
                  None                                                    
                      None                                                
                          None                                            
                              None                                        
                                  None                                    
                                      None                                
                                          None                            
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     In Table 4, the term &#34;None&#34; in the column &#34;Blooming&#34; means that there occurred no blooming for three months or more when the crosslinked material in question was kept at room temperature; and the terms &#34;None&#34; , &#34;Slight&#34; and &#34;Considerable&#34; in the column &#34;Odor&#34; represent the intensities of odor generated from the crosslinked materials in question when kept at room temperature. 
     The above results show that the odor generated by decomposition of the organic peroxides in the crosslinked materials when the peroxide according to the present invention, i.e., 1,1-bis(tert-butylperoxy)-cyclododecane, is employed is less than that when the publicly-known peroxides such as dicumyl peroxide and n-butyl 4,4-bis(tert-butylperoxy) valerate are employed, and is as low as that when 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane is used; that the physical properties of the crosslinked materials when the peroxide according to the present invention is used are about the same as those in the case where the publicly-known peroxides are employed; and that the peroxide according to the present invention is useful as a crosslinking agent for the above reasons. 
     In addition, the cyclododecane peroxides similar to the peroxide of the present invention, such as 1,1-bis(tert-amylperoxy)-cyclododecane and 1,1-bis(tert-hexylperoxy)cyclododecane, are low in crosslinking efficiency. Therefore, only the peroxide of the present invention is useful as crosslinking agent among these similar cyclododecane peroxides. 
     The above results also show that the use of the peroxide of the present invention in combination with crosslinking co-agents such as sulfur and ethyleneglycol-dimethacrylate results in a remarkable improvement in the physical properties of the crosslinked materials produced. 
     EXAMPLE IV 
     Comparison of crosslinking rates: 
     Regarding the peroxide of the present invention, the cyclododecane peroxides similar thereto and the publicly-known peroxides, the crosslinking rates in the crosslinking process of EPDM (Esprene 502) were measured and compared. The crosslinking rates were measured at 150° C using a rheometer. The results are shown in Table 6. 
     The composition of the polymer mixtures used in this test is as follows: 
     
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EPDM (Esprene 502)   100 parts by weight                                  
Stearic acid          1 part by weight                                    
Zinc white            5 parts by weight                                   
HAF carbon black      40 parts by weight                                  
Peroxide (diluted to 40% with                                             
calcium carbonate)   0.01 mole                                            
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                       Table 5.                                                    
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Comparison of Crosslinking Rates                                          
                       Curing   Curing                                    
                       temp.    time                                      
peroxide               (° C)                                       
                                (min.)                                    
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1,1-bis(tert-butylperoxy)cyclododecane                                    
                       150      14                                        
1,1-bis(tert-amylperoxy)cyclododecane                                     
                       150      12                                        
1,1-bis(tert-hexlperoxy)cyclododecane                                     
                       150      10.5                                      
1,1-bis(1,1,3,3-tetramethylbutylperoxy)-                                  
                       150      4.5                                       
cyclododecane                                                             
1,1-bis(tert-butylperoxy)-3,3,5-                                          
                       150      9.5                                       
trimethylcyclohexane                                                      
n-butyl 4,4-bis)tert-butylperoxy)                                         
                       150      31                                        
valerate                                                                  
Dicumyl peroxide       150      59                                        
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     EXAMPLE V 
     Comparision of volatility: 
     The volatilities of the peroxide of the present invention and the publicy-known peroxides were compared. Tests were carried out using EPDM (Esprene 502) as the polymer. 
     The mixing process was carried out by a roll mixer. The thus obtained polymer mixtures were allowed to stand laying open in the atmosphere at room temperatures for 10 - 30 days and then were subjected to the crosslinking process in a press at a pressure of 150 kg/cm 2 , at temperature of 150° C and for 20 minutes. The physical properties of the resultant crosslinked materials were measured and the results are shown in Table 6. 
     In Table 6, the term &#34;yes&#34; or &#34;none&#34; in the column Existence of volatility&#34; was determined depending on whether the physical properties of the crosslinked material were deteriorated or not, because when the peroxide in a polymer is volatilized, the percentage of the peroxide in the polymer mixture is decreased, with the result being that the physical properties of the crosslinked material is as a matter of course deteriorated. 
     The composition of the polymer mixtures used in this test is as follows: 
     
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EPDM (Esprene 502)   100 parts by weight                                  
Stearic acid          1 part by weight                                    
Zinc white            5 parts by weight                                   
HAF carbon black      40 parts by weight                                  
Peroxide (diluted to 40% with                                             
calcium carbonate)   0.01 mole                                            
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     The tensile strength and elongation of the crosslinked material was measured according to the same method as that described in Example 3. 
     The above results show that the physical properties of a crosslinked material obtained from a polymer mixture containing the peroxide of the present invention which was laid open in the atmosphere for 30 days, was not deteriorated, and that the peroxide of the present invention volatizes a very little (or scarcely any) and is good because the loss of the peroxide due to volatilization is very little during the mixing process. 
     
                                           Table 6.                                
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Comparision of Volatility                                                 
           Physical Properties                                            
        Days                                                              
           Tensile                                                        
                Elonga-                                                   
                     100 %                                                
                          200% 300 %                                      
                                    spring                                
        laid                                                              
           strength                                                       
                tion modulus                                              
                          modulus                                         
                               modulus                                    
                                    hardness                              
                                         existence                        
Peroxide                                                                  
        open                                                              
           (kg/cm.sup.2)                                                  
                %    (kg/cm.sup.2)                                        
                          (kg/cm.sup.2)                                   
                               (kg/cm.sup.2)                              
                                    (HS) of volatility                    
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         0 201  550  18   31   74   61                                    
1,1-bis(tert-                                                             
        10 200  550  18   30   75   61   None                             
butylperoxy)                                                              
        20 202  540  17   32   74   61                                    
cyclododecane                                                             
        30 201  550  18   31   74   62                                    
1,1-bis(tert-                                                             
         0 202  510  16   32   74   61                                    
butylperoxy)-                                                             
        10 190  510  15   31   72   61   consider-                        
3,3,5-trimethyl-                                                          
        20 188  500  14   29   68   60   able                             
cyclohexane                                                               
        30 160  510  14   27   60   68                                    
n-butyl  0 197  400  19   34   75   62                                    
4,4-bis(tert-                                                             
        10 195  400  19   35   74   62   slightly                         
butylperoxy)                                                              
        20 195  410  19   34   74   61   yes                              
valerate                                                                  
        30 180  400  18   33   70   61                                    
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     EXAMPLE VI 
     Crosslinking velocity at 120° C (Comparison of existence of scorching) 
     Regarding the peroxide of the cyclododecane present invention, the peroxides similar thereto and the publicly-known peroxides, the crosslinking velocity at 120° C (mixing temperature) in the crosslinking process of EPDM (Esprene 502) was measured by a rheometer, to thereby compare the existence of the scorching of respective crosslinking materials. The attached drawing shows the rheometer curves for several kinds of peroxides. Curve (1) is for 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, curve (2) for 1,1-bis(t-butylperoxy)cyclododecane, curve (3) for n-butyl 4,4-bis(t-butylperoxy) valerate and curve (4) is for dicumylperoxide. 
     Existence of scorching was determined by the result of whether or not the time consumed for increasing the torque value in the respective rheometer curves by an amount of 5 Kg. cm the from the minimum value is less than 30 minutes. Namely, there is danger of scorching accurring when the time is less than 30 minutes, but when the time is more than 30 minutes, scorching does not take place. The composition of the polymer mixtures used in this test is same as that used in the preceding Examples. The above results and the results of Example 2 show that the peroxide of the present invention is faster in crosslinking velocity than dicumylperoxide and n-butyl 4,4-bis(tert-butylperoxy) valerate and is slower than 1,1-bis (tert-butylperoxy)3,3,5- trimethylcyclohexane and accordingly, according to the present invention, scorching does not occur at the mixing temperature (110°- 130° C) but the crosslinking velocity is fast at the crosslinking temperature (140 - 150° C). 
     
                       Table 7.                                                    
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Crosslinking velocity at 120° C                                    
(Comparision of existence of scorching)                                   
             Time consumed for                                            
             increasing torque value                                      
             5 kgcm from the                                              
             minimum value thereof                                        
                              Danger of                                   
Peroxide     (min)            Scorching                                   
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1,1-bis                                                                   
(tert-butylperoxy)                                                        
             45               none                                        
cyclododecane                                                             
1,1-bis                                                                   
(tert-butylperoxy)                                                        
             20               yes                                         
3,3,5-trimethyloy-                                                        
clohexane                                                                 
n-butyl 4,4-bis                                                           
(tert-butylperoxy)                                                        
             55               none                                        
valerate                                                                  
Dicumyl peroxide                                                          
                90 up         none                                        
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     EXAMPLE VII 
     Crosslinking tests of ethylene-vinyl acetate copolymer (produced by Japan Polychemical Co., Ltd., Trade Name: Ultrasen 637) using the peroxide of the present invention, cyclododecane peroxides similar thereto and publicy-known peroxides. 
     The mixing process of the polymer mixtures, crosslinking reaction, tension tests, evaluation of odor and blooming were conducted in the same manner as that described in Examiner 1. 
     The compositions of the polymer mixtures, and the physical properties of crosslinked materials are shown respectively in Table 8 and Table 9. 
     
                       Table 8.                                                    
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Composition of Polymer Mixture                                            
(Parts by weight)                                                         
Specimen No.   1      2      3    4    5    6                             
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Ethylene-vinyl acetate-                                                   
copolymer (ultrasen 634)                                                  
               100    100    100  100  100  100                           
Stearic acid   1      1      1    1    1    1                             
1,1-bis(tert-butylperoxy)-                                                
cyclododecane  8.60   --     --   --   --   --                            
1,1-bis(tert-amylperoxy)-                                                 
cyclododecane  --     9.30   --   --   --   --                            
1,1-bis(tert-hexylperoxy)-                                                
cyclododecane  --     --     10.0 --   --   --                            
1,1-bis(tert-butylperoxy)3,                                               
3,5-trimethylcyclohexane                                                  
               --     --     --   7.55 --   --                            
n-butyl 4,4-bis(tert-butyl-                                               
peroxy)valerate                                                           
               --     --     --   --   8.35 --                            
Dicumyl peroxide                                                          
               --     --     --   --   --   6.75                          
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                                           Table 9.                                
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Physical Properties of                                                    
Crosslinked Material                                                      
Specimen No.  1   2   3   4   5   6                                       
Curing temperature (° C)                                           
              150 150 150 150 150 160                                     
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Tensile Curing                                                            
            10                                                            
              301 255 240 302 277 297                                     
strength                                                                  
        time                                                              
            20                                                            
              310 250 245 318 249 289                                     
(Kg/cm.sup.2)                                                             
        (min.)                                                            
            30                                                            
              310 230 230 298 241 263                                     
            40                                                            
              295 210 230 --  --  --                                      
Elongation                                                                
        Curing                                                            
            10                                                            
              570 570 550 550 590 520                                     
(%)     time                                                              
            20                                                            
              540 580 560 560 560 490                                     
        (min.)                                                            
            30                                                            
              550 570 560 570 550 490                                     
            40                                                            
              560 560 550 --  --  --                                      
100% modulus                                                              
        Curing                                                            
            10                                                            
              36  35  33   35  34  35                                     
(Kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              36  34  33   35  34  34                                     
        (min.)                                                            
            30                                                            
              35  30  33   34  33  33                                     
            40                                                            
              34  30  34  --  --  --                                      
200% modulus                                                              
        Curing                                                            
            10                                                            
              43  41  41   43  40  42                                     
(Kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              46  38  41  11 42                                           
                                41                                        
                                   41                                     
        (min.)                                                            
            30                                                            
              43  38  41   41  40  41                                     
            40                                                            
              40  38  40  --  --  --                                      
300% modulus                                                              
        Curing                                                            
            10                                                            
              53  48  51   55  50  52                                     
(Kg/cm.sup.2)                                                             
        time                                                              
            20                                                            
              57  46  50   52  50  52                                     
        (min.)                                                            
            30                                                            
              54  45  50   52  50  51                                     
            40                                                            
              50  47  51  --  --  --                                      
Odor          none                                                        
                  none                                                    
                      none                                                
                          none                                            
                              slight                                      
                                  consi-                                  
                                  dera-                                   
                                  ble                                     
Blooming      none                                                        
                  none                                                    
                      none                                                
                          none                                            
                              none                                        
                                  none                                    
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     The above results show that the odor of the crosslinked composition generated by decomposition of the peroxide of the present invention as well as in case of crosslinking EPDM as shown in Example 3, is less than that generated by decomposition of publicly known peroxides, for instance, dicumylperoxide or n-butyl 4,4-bis(tert-butylperoxy) valerate and is same as that of 1,1-bis(tert-butylperoxy) 3,3,5-trimethylcyclohexane and the physical properties of the crosslinked composition are the same as those obtained by the publicly-known peroxides and the peroxide of the present invention is very useful as a crosslinking agent. The above results show that 1,1-bis(t-amylperoxy)cyclododecane and 1,1-bis(t-hexylperoxy)cyclododecane, which are cyclododencane peroxides similar to that of the present invention are low in the efficiency of crosslinking and also the surface of the crosslinking composition is not uniform and accordingly said peroxides are not preferable as crosslinking agents. 
     Extraction tests with chloroform: 
     Tests of extracting ethylene-vinyl acetate copolymer which was crosslinked by the peroxide of the present invention, and peroxide similar thereto, with chloroform, were carried out. A crosslinked composition of about lmm square was weighed accurately on a brass net of 100 mm mesh and the net was folded into a bag so that the crosslinked composition did not escape. 
     Then the crosslinked composition was extracted with chloroform for 8 hours using a Soxhlet extractor. 
     The chloroform was renewed every 6-8 hours. After extraction, the net and its contents were put into a vacuum decicator and were dried at 50° C to get a constant weight thereof. The resultant gel was weighed and the percentage of its weight based on the weight of the starting material, was calculated. 
     When the percentage of the resultant gel is over 90%, the crosslinking reaction was conducted completely. 
     The results are shown in Table 10. The specimens used in these tests were the same as those used in the preceding Examples for measuring the physical properties therefor. 
     
                       Table 10.                                                   
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Extraction tests with chloroform                                          
resultant quantity of gel (%)                                             
       Specimen No.                                                       
Curing                                                                    
time (min.)                                                               
         1       2       3     4     5     6                              
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10       92.7    88.7    88.3  92.2  92.0  95.5                           
20       92.4    87.9    87.7  92.6  92.6  97.0                           
30       92.6    88.3    88.7  92.1  92.7  96.5                           
40       92.3    89.8    88.4  92.2  92.6  96.7                           
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     The above results show that the peroxide of the present invention produces as much gels as the publicly known peroxides do and the crosslinking reaction with the peroxide of the present invention is completely conducted, whereas the percentage of gel product for 1,1-bis(tert-amylperoxy)cyclododecane and 1,1-bis(tert-hexylperoxy)cyclododecane is less than 90% and neither crosslinking reaction was sufficiently conducted.