Patent Publication Number: US-4321338-A

Title: Novel chlorinated polymer and coating composition employing the same

Description:
THE DETAILED EXPLANATION OF THE INVENTION 
     This invention relates to the novel chlorinated polymer and the coating composition employing the same polymer. More particularly, this invention relates to the novel chlorinated polymethylpentene and the coating composition employing the said polymer which are specially excellent in thermo-resistance and in thermal stability, but yet freely soluble in the inexpensive multi-purpose solvent. Due to the fact that chlorinated polyolefins, which have been obtained by chlorinating multi-purpose polymers, such as rubber, polyethylene and polypropylene in a chlorine resistant solvent, are capable of forming films which have excellent weather resistance, water resistance and chemical resistance properties, these chlorinated polyolefins have widely been used as the chief ingredient of coating composition, such as clear lacquer, paint, ink and adhesives. But since the conventional chlorinated polyolefins soften at the temperature in the range of 100°-200° C., the paint, ink, adhesive which had used them as vehicles have been poor in thermo-resistance. Therefore, it has been normal either to use resin which has high softening temperature together with the said chlorinated polyolefines or to use resin with thermo-setting property together with the said chlorinated polyolefines in order to improve the thermo-softening characteristic. For this reason, it has long been desired to improve thermo-resistance of these conventional chlorinated polyolefines. 
     That is to say, it has been the recent trend to raise the temperature for drying during line painting process or during printing process in order to improve painting operation and also to increase the printing speed. But during these operations, many problems have been encountered such as troubles of blocking, creeping, scratches etc., and deterioration of printing effects which were apparently caused by the softening of coated surface by heat. And not only limited to the softening point, the commonly used conventional chlorinated polyolefins, had such shortcomings as clear film made therefrom have been liable to discolor by the heat or the transmittance of light. In view of above, it has urgently been needed to surmount these poor thermo-stability of the chlorinated polyolefines. 
     While on the one hand, it has frequently been done to add these conventional chlorinated polyolefins into rubber adhesive for the improvement of creep resistance property. Moreover, the creep resistance property at elevated temperature is recently demanded in applications such as automobile and aircraft industries. Therefore, it has long been desired to develop the additive resin having good compatibility with rubber adhesive and having high softening temperature together with more favorable thermo-stability. 
     On the other hand, it has also been desired to reduce the quantity of solvent remaining in the ink film formed after printing, from standpoints of prevention of atmospheric pollution and of safety and hygiene of working environment. But as the conventional chlorinated polyolefins of prior known art have been poor in solvent release, they have not been satisfactory materials. 
     As a result of overviewing in various ways to improve the shortcomings inherent in the conventional chlorinated polyolefins of prior known art, the inventors discovered that the chlorinated polymethylpentene, which is comprised of isotactic poly-4-methylpentene-1 with the melt index of 8-70 g/10 min. at a condition of 260° C. and 5 kg (ASTM D 1238-65T) which had been uniformly dissolved into chlorine resistant solvent and which is uniformly chlorinated to not less than 50 weight % of chlorine content in condition of solution thereof, can be dissolved well into the inexpensive multi-purpose solvent such as xylene, toluene, solvesso 100, etc., and moreover has excellent thermo-resistant property and thermo-stable property as compared with those of conventional chlorinated polyolefins. 
     Chlorinated polymer which is obtained by chlorinating an amorphous polymer obtained by cationic polymerization of 4-methylpentene-1 to the chlorine content in the range of 25-50 weight % has been well known by U.S. Pat. No. 3,484,423 specification. 
     And, chlorinated polymer containing chlorine content in the range of 5-61 weight % obtained by the suspension chlorination of the finely pulverized isotactic poly-4-methylpentent-1, which is obtained by polymerizing 4-methylpentene-1 with Zielgler-Natta catalyst, in carbon tetrachloride at room temperature, is also well known by Journal of Polymer Science, 55, 169-180, 1961. 
     Although chlorinated polymers, which have high softening temperature, are available through this suspension chlorination of isotactic poly-4-methylpentene-1 in carbon tetrachloride, with increasing chlorine content of polymers, the thermal stability of those polymers are so inferior than that of conventional chlorine containing polymers such as polyvinylchloride etc., that they tend to decrease their solution viscosity markedly and to show significant decrease in weight caused by the dehydrochlorination when they are heated in air. Thus, about the said polymer, applications of significant advantage have not been found. Therefore, as a result of conducting various experiments on the chlorinating of both the amorphous polymer and the isotactic polymer of 4-methylpentene-1, the inventors of this invention have discovered that chlorinated polymethylpentene which is obtained by uniformly chlorinating the isotactic poly-4-methylpentene-1 having the melt index of 8-70 g/10 min. (ASTM D 1238-65T) at the condition of 260° C. and 5 kg in condition of a solution thereof to not less than 50 weight % of chlorine content is extremely adaptable as a coating ingredient, and come to achieve this invention. That is to say, the inventors studied on the uniform chlorination of the isotactic poly-4-methylpentene-1, which has never been attempted. Then uniformly chlorinated poly-4-methylpentene-1 with desired chlorine content ratio was obtained by completely dissolving isotactic poly- 4-methylpentene-1 having the melt index of 8-70 g/10 min. at 260° C. and 5 kg (ASTM D 1238-65T) into carbon tetrachloride under increased pressure at a temperature higher than its boiling point, and by blowing chlorine gas into the solution in which the poly-4-methylpentene-1 was completely dissolved. As a result of closely examining various properties of the chlorinated polymers thus obtained, it was discovered that among these uniformly chlorinated polymers, the polymers with high chlorine content--with the chlorine content of not less than 50 weight %--had a very high softening temperature, which is not at all inferior to that of chlorinated polymer obtained by the said well known non-uniform chlorinating method. What is more, with respect to thermal stability, it was discovered that the said invented polymer was excellent and more superior even compared with not only the said non-uniformly chlorinated poly-4-methylpentene but also the conventionally well known chlorine containing polymers, such as polyvinyl chloride, chlorinated polyvinyl chloride, chlorinated rubber, chlorinated polyethylene, chlorinated polypropylene, etc. Therefore, the inventors arrived at achieving this invention. While the substance obtained by this invention is a novel chlorinated polymer which is obtained by uniformly chlorinating poly-4-methylpentene-1 which have never heretofore been attempted, various coating compositions were produced using this invented substance in this invention. It was revealed that the invented polymer not only excelled in various properties relating to such as hardness and tenacity but also has favorable heat resistance which could not be achieved by the conventional chlorinated polyolefin. In other words, it was found that the invented polymer had thermal deformation resistance, thermal decomposition resistance and good solvent release. Thus this invention offers novel and useful coating composition for paint, printing ink, over printing varnish, adhesives, etc. 
     The details of the invention are explained in the following paragraphs: 
     The invented polymer is prepared by uniformly dissolving the isotactic poly-4-methylpentene-1 having the melt index of 8-70 g/10 min. measured at 260° C. under 5 kg load (ASTM D 1238-65T) into chlorine resistant solvent such as carbon tetrachloride under increased pressure at a temperature higher than the boiling point of the solvent and by blowing chlorine gas into the said solution, maintaining the uniformly dissolved condition throughout the process to chlorinate the polymer to chlorine content above 50 weight %. 
     Upon preparing the same, the reaction can be smoothly effected in a shorter period of time when organic peroxides or diazo compounds which have been conventionally used as chlorinating catalysts, are used, or when lights or radiations are used. 
     In this invention, the reason why the melt index of the isotactic poly-4-methylpentene-1 is limited to 8-70 g/10 min. at the temperature of 260° C. under 5 kg lies in the fact that the said isotactic poly-4-methylpentene-1 having this range of melt index value can be uniformly dissolved into chlorine resistant solvent such as carbon tetrachloride within the temperature and pressure ranging from 130° C. and 3.5 kg/cm 2  to the normal temperature and normal pressure. 
     And in this invention, the reason why the chlorine content in the uniformly chlorinated polymer of the isotactic poly-4-methylpentene-1 is limited to above 50 weight % is attributed to the fact that polymers having chlorine content below 50 weight % is not capable of adequately satisfying the thermal property which is the feature of this invention. 
     As mentioned in the foregoing, the invented substance which is obtained by uniformly chlorinating process in the chlorine resistant solvent, can be separated out of the solvent by conventionally well-known process for instance, steam distillation method, or precipitation method using solvent that cannot dissolve chlorinated polymer (in other words it is non-solvent to the chlorinated polymer), thereafter the separated polymer can be dissolved into solvent which is suitable for end use to give various kind of coating compositions. And, this invented substance can also be used for preparing a objective coating composition by method of directly substituting solvent and others without isolating the invented polymer from the reaction liquor after the above chlorinating. 
     The results of experiments relating to various properties such as, heat decomposition resistance and heat deformation resistance of the invented substance at high temperatures are indicated in the following tables. 
     
                       TABLE 1                                                     
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               Weight loss (%) after 40 minutes                           
               205° C.                                             
                         235° C.                                   
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Polyvinyl chloride resin                                                  
                 1           22                                           
The invented substance                                                    
                 2            8                                           
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     From above table, it can be recognized that the invented substance displays excellent stability at elevated temperatures. 
     When polyvinylchloride resin is used in a coating composition, surging dehydrochlorination occurs as the temperature is elevated. In contrast to this, when the invented polymer is used, it does not decompose surgingly as the loss occurs in proportion to the lapse of time (the relationship of elapsed time to the loss is linear). 
    
    
     Next, the invention is explained in detail in accordance with examples. 
     EXAMPLE 1 
     200 g each of two types of isotactic polymer of 4-methylpentene-1 having the melt indexes of 8 g/10 min. and 70 g/10 min. (ASTM D 1238-65T) were dissolved into 5 l each of carbon tetrachloride respectively. After these were dissolved well at 110° C. under pressure of 2 kg/cm 2 , air was purged therefrom, and then chlorinating was performed by blowing chlorine gas into a reactor from its bottom section under the irradiation with light. 
     In the course of chlorination, some portions of the reaction mixture were taken out occasionally, then they were pulverized through the steam distillation one by one, thus white powders having from 50 wt% of chlorine to ultimate 75 wt% of chlorine were obtained. The chlorine content, the viscosity of the solution, softening temperatures and thermal decomposition resistance of them are indicated in the following table. For the sake of comparison, comparison tests were performed on commercially available chlorinated rubber. 
     
                                           TABLE 2                                 
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                                             Comparative                  
               Examples                      Example                      
                                   M.I. =    Chlorinated                  
               M.I = 8 g/10 min.   70 g/10 min.                           
                                             Rubber SUPER-                
Testing Items                                                             
       Examples                                                           
               A    B    C    D    E    F    CHLON CR-20                  
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Chlorine content (%)                                                      
                54   62  66.7 72.1 59.7 65.4  65                          
Viscosity of solution (CP)                                                
               100,000                                                    
                    11,000                                                
                         610  100  17,500                                 
                                        3,080                             
                                             1,050                        
Softening temperature (°C.)                                        
               250  280  &gt;300 &gt;300 270  &gt;300 195                          
Thermal discoloring property                                              
               Slightly                                                   
                    Did not                                               
                         Did not                                          
                              Did not                                     
                                   Did not                                
                                        Did not                           
                                             Turned into                  
               yellow                                                     
                    discolor                                              
                         discolor                                         
                              discolor                                    
                                   discolor                               
                                        discolor                          
                                             black                        
Storage                                                                   
       Fluidity at                                                        
               O    O    O    O    O    O    O                            
stability                                                                 
       -10° C.                                                     
of varnish                                                                
       Nail rust                                                          
               O    O    O    O    O    O    X                            
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 Legends:                                                                 
 1. Viscosity of Solution:                                                
 Indicates centipoise of 40 weight % toluene solution at 25° C.    
 2. Softening temperature:                                                
 Measured by melting point measuring apparatus.                           
 3. Thermal discoloring property:                                         
 Discoloring after heating at 180°  C. for 30 minutes.             
 4. Storage stability of varnish:                                         
 a: Fluidity at -10° C.: Fluidity was tested by preserving at      
 -10° C. and at a room temperature.                                
 O -- good                                                                
 b. Nail rust (corrosion test of nail): A test was done to see whether the
 rust occurs on the nail immersed in 20% toluene solution for 5 days at a 
 room temperature.                                                        
 O -- No rust observed                                                    
 X -- Rust observed                                                       
 
    
     As it can be learned from Table 2, the invented substance is proven to possess very high softening temperature and thermal stability. 
     Furthermore, in order to clarify this thermal stability quantitatively, the results of measurement made on the relationship between heating time at 162° C. in air oven and weight loss of the substance B in Table 2, commercial polyvinyl chloride resin and commercial chlorinated rubber. 
     
                       TABLE 3                                                     
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         Resin                                                            
                                 Chlorinated                              
Heating Time                                                              
           Example B   PVC       Rubber                                   
______________________________________                                    
 0 hrs.    0           0         0                                        
 5 hrs.    0           0.98      1.44                                     
40 hrs.    2.81        3.05      3.84                                     
75 hrs.    3.93        7.12      12.62                                    
______________________________________                                    
 PVC: Polyvinyl chloride reagent of Katayama Chemical Industry Co., Ltd.  
 Chlorinated rubber: Commercial products of ICI.                          
 
    
     From Table 3, it also can be understood that the invented substance is a novel polymer which suffers less thermal decomposition than the commercial chlorinated rubber and the commercial polyvinyl chloride do. 
     EXAMPLE 2 
     (Printing ink) 
     Gravure printing ink was prepared by using above polymer B of the above example and chlorinated rubber of comparative example. That is, 20% toluene solutions containing 18 g of resin and 72 g of toluene were respectively prepared and to the solution, 10 g of pigment (Carmine 6BN produced by Toyo Ink Manufacturing Co., Ltd.) was added respectively. After mixing these for 2 hours by a sand mill to give printing inks, the inks, which have the same amount of solid component in each of them, were printed on a coating paper to form ink films of 5-6μ. After completely drying films at room temperature, tests were made on color development, thermal resistance and storage stability of the inks. 
     
                       TABLE 4                                                     
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                         Comparative                                      
                         Example                                          
                         (Chlorinated                                     
               Example 2 Rubber)                                          
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Color development of the ink                                              
                     O               O                                    
Thermal resistance                                                        
            150° C.                                                
                     V       ⊚                             
                                   V     O                                
of the ink surface                                                        
            160° C.                                                
                     V       ⊚                             
                                   V     Δ                          
            180° C.                                                
                     V       ⊚                             
                                   V     X                                
Storage      50° C.                                                
                     V       ⊚                             
                                   V     Δ                          
stability   -10° C.                                                
                     V       O     V     Δ                          
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 Color development: Judged by color density                               
 O: good color development                                                
 Thermal resistance: The printed paper which was overlapped on the printed
 surface with a sheet of fine paper, was pressed with the heat sealing bar
 maintained at above mentioned temperature respectively with the pressure 
 of 2 kg/cm.sup.2 for 10 sec. After cooling for 30 minutes, the fine paper
 overlapped is peeled off. Judgement was made on the basis of its peeling 
 condition of the paper.                                                  
 ⊚: no peel off                                            
 O: peeled off less than 5%                                               
 Δ: peeled off less than 30%                                        
 X: peeled off more than 50%                                              
 Storage stability: Observation was made either on the rust from the tin  
 can at 50° C., or the gelling of the ink and the change of fluidit
 thereof at -10° C.                                                
 O: good, Δ: tolerable                                              
 
    
     EXAMPLE 3 
     (The solvent release of clear coating film) 
     As for the coated films, such as that of printing inks, lacqurs, and over printing varnish etc., which usually contain high proportions of resin in them, the rapid solvent release is needed, not only for the fast development of their inherent film properties but also from the stand point of hygiene. 
     Therefore, the comparison test of solvent releasing property was made on the invented composition as the following. 
     
         ______________________________________                                    
Composition:                                                              
           Resin             14.0 g                                       
           Plasticizer (Toyopalax A-40)                                   
                             6.0 g                                        
           Toluene           80.0 g                                       
           Total:            100.0 g                                      
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                       TABLE 5                                                     
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Residual Ratio of Toluene (%)                                             
                          Comparative                                     
                          Example                                         
Drying          Examples  Chlorinated                                     
Condition Resin     A      B    Rubber                                    
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20° C. after 18 hours                                              
                5.1    3.7    7.8                                         
60° C. after 5 hours                                               
                1.5    1.3    3.9                                         
60° C. after 18 hours                                              
                0.3    0.04   1.1                                         
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     Conditions: 5±0.1 g of toluene solution containing 20% resin was precisely weighed and taken over to a 9 cm diameter Petri dish, and measurements were made on the residue after air drying for 18 hours and the residue after drying at 60° C. respectively. The residual amounts of toluene were determined using P-xylene as an internal standard. 
     EXAMPLE 4 
     (Over printing varnish) 
     Using the invented substance indicated as B in Example 1, over printing varnish was prepared compounding small amount of chlorinated paraffin with it. Pencil hardness test was performed on the dried film of the over printing varnish. Concerning chlorinated rubber which has presently been used as quick drying thermal resistant over printing varnish, the same test was performed as reference which was shown as follows. 
     
                       TABLE 6                                                     
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Pencil Hardness of Dried Film                                             
(Room Temperature)                                                        
            Resin                                                         
Chlorinated   Invented       Chlorinated                                  
Paraffin Toyopalax A-40                                                   
              Substance      Rubber CR-10                                 
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9:1           4 H            3 H                                          
8:2           3 H              H                                          
7:3             H            HB                                           
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     As it can be recognized from Table 6, a coating composition having excellent surface hardness can be obtained by using the invented polymer. 
     More practically, as the invented polymer is freely compatible with chlorinated rubber, chlorinated polypropylene, etc., it can be advantageously added to the resins which are commonly used in the above mentioned coating compound to improve thermo-blocking resistance and surface hardness. 
     EXAMPLE 5 
     (Paint) 
     A side from the distinctive features already mentioned above, weather resisting property is also essential for paint. 
     Together with the substances C and E prepared under example 1, using chlorinated rubber, finish coating paints were prepared respectively and the change of whitness by irradiation of ultra violet rays was traced. The composition of the paint and specimen pieces were prepared in the following manner. 
     
         ______________________________________                                    
Composition of paint:                                                     
             Resin              21.4 g                                    
             Plasticizer (Toyopalax A-40)                                 
                                9.5 g                                     
             Titanium dioxide (R-820)                                     
                                26.5 g                                    
             Stabilizer (Epikote 828)                                     
                                0.5 g                                     
             Thixotropic agent (Benton 34)                                
                                1.5 g                                     
             Xylene             40.6 g                                    
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     Test specimens were prepared by applying the paint having above composition, which was prepared by a sand mill, with a brush on the primer coated sheet, which was sand-blasted and then was under-coated by &#34;epoxy zinc-rich primer&#34;. 
     After above specimen sheet had been dried with air for 7 days, it is irradiated by 20 watt mercury light at a distance of 30 cm from the specimen pieces and the whitness was traced at predetermined time intervals. 
     
                       TABLE 7                                                     
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the Relationship Between Ultra Violet                                     
Rays Irradiation Time and The Whiteness                                   
(Degree of Whiteness: %)                                                  
                         Comparative                                      
                         Example                                          
               Examples  Chlorinated                                      
Irradiation Time                                                          
            Resin    C       E     Rubber                                 
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 0 hours         81.5    83.8    85.6                                     
40 hours         77      80      77                                       
80 hours         76      79      75                                       
160 hours        75      78      70                                       
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     As it can be evidently recognized from Table 7, the paint which contains the invented polymer possesses light resistance which is not at all inferior to that of chlorinated rubber. 
     EXAMPLE 6 
     (Application as flame retarder) 
     The following composition having the invented polymer and polyethylene as a flammable polyolefine was subjected to combustion test. 
     
         ______________________________________                                    
Composition:         Polyethylene                                         
             Resin               42.5 g                                   
                     Flo-thene G801                                       
           The invented polymer                                           
                         5.0 g                                            
           Antimonytrioxide                                               
                         2.5 g                                            
           Total:        50.0                                             
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     After blending the above composition well, and compounding for 10 minutes with rolls (surface temperature: 145° C.), the composition was formed into a sheet-like shape (width: 1 cm, thickness: 1 mm and length: 10 cm), on which the combustion test was performed in accordance with the requirements of JIS K-6911. 
     
                       TABLE 8                                                     
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Combustion Test Results                                                   
          Example    Comparative Example                                  
          Flame               Polyethylene                                
          Retarder   Poly-    (45 g) Sb.sub.2 O.sub.3                     
Test Item   A      B      E    ethylene                                   
                                      (5 g)                               
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Combustion time                                                           
            5.1    2.1    3.5  ∞                                    
                                      ∞                             
(sec.)                                                                    
Combustion  6.3    4.8    5.9  ∞                                    
                                      ∞                             
Distance (cm)                                                             
Self-extinguishing                                                        
            Yes    Yes    Yes  No     No                                  
Property                                                                  
______________________________________                                    
 
    
     From above results, it was discovered that the invented substance has the advantage of giving self-extinguishing property to flammable plastic (polyethylene) and also has additional advantages when is compared with chlorinated paraffin which is commonly used for this application, by showing no melt flow of the specimens during the test. 
     By making use of these distinctive features, the invented substance is capable of making flame retardant paint with the least discoloring property and excellent melt flow resistance against the flaming.