Patent Publication Number: US-4654391-A

Title: Grafting of epoxy resin on amide

Description:
FIELD OF THE INVENTION 
     It is an object of the present invention to provide novel polymeric composition of matter. More specifically, the invention relates to polymeric materials composed of chlorine containing polymers partially substituted by thio amide group as component (A) and epoxy moieties as component (B). The reaction of components (A) and (B) provide a family of novel polymers containing chlorine, sulfur and nitrogen. 
     BACKGROUND OF THE INVENTION 
     Chemically modified polyvinyl chloride compositions are numerous and well-known. The usual approach to the modification of this type of polymer is by means of grafting onto the macromolecule of various other reactive monomers, telomers or other entities, by chemical, photochemical or radiation induced reactions. Processes of this kind are well documented. Thus, A. Chapiro, in his book &#34;Radiation Chemistry of Polymeric Systems&#34;, V., 15, 1962, extensively quotes many cases of radiation grafting of various monomers to P.V.C. More recently, Kennedy has developed a general method for the chemical grafting of certain monomers to P.V.C., using an alkyl-aluminum catalyst (Cationic Graft Copolymerization, Ed. J. P. Kennedy, Interscience, 1977). No commercial application has, to our knowledge, resulted from these and similar approaches for several reasons. Radiation-grafting requires expensive and cumbersome equipment, as well as elaborate safety precautions. The catalytic methods of Kennedy involve the use of expensive and dangerous-to-handle metallo-organic compounds. In addition, to effect a grafting reaction on P.V.C. in accordance with the various methods described in the literature, the P.V.C. has to be dissolved in an organic anhydrous solvent, such as cyclohexanone, or tetrahydrofuran, forming very viscous solutions even at quite low concentrations, which are extremely difficult to handle in a chemical reaction. This is the main reason why previous attempts to modify P.V.C. by grafting reactions remain to date a laboratory exercise only. 
     The interest in graft-modified P.V.C. is very considerable. This is spurred by the various well known shortcomings of neat polyvinyl chloride, especially when intended for certain particular uses. Thus, P.V.C. is largely used in a highly plasticized form, for the production of films, tubings, coatings, etc. The common plasticizers used, such as the various phthalate esters, and particularly di-2-ethylhexyl phthalate, lack in &#34;permanence&#34; and tend to exude in time from the polymer compositions, leaving a brittle and friable object. The extraction of plasticizer--which does not form a chemical bond with the macromolecule--is particularly accelerated by contact with various solvents that leach it out from the polymer matrix. Such plasticized compositions are, therefore, restricted to use in solvent-less environments. 
     As a result of the possible exudation of the phthalate plasticizers these compositions have lately become a subject for review, since they have been shown to induce tumors in the liver of mice (C. E. News p. 5, May 5, 1980). 
     Another well-known drawback of commercial P.V.C. compositions is their hydrophobic nature. This results in the accumulation of static electricity, and the easy deposition of dust, which in certain applications (music records, greenhouse coverings, textile fibers) is very deleterious. 
     A recent U.S. Pat. No. 4,298,714 by Levin and Vofsi relating to the modification of P.V.C. by thio-etheric group (i.e. --S--(CH 2  --CH 2  --O) n  --R), reveals the possibility of grafting on P.V.C. the above groups and thus creating a composition of material which behaves like internally plasticized P.V.C. 
     SUMMARY OF THE INVENTION 
     Using epoxy resin as a stabilizer for P.V.C. has the disadvantage that the stabilizer will migrate out with time from the polymer matrix. However, attaching the epoxy resin by chemical bond to the P.V.C. will eliminate the migration problem, will create a polymer characterized by the durability of the epoxy resin and the flame retardent property of the P.V.C. backbone. Also, the epoxy resin, while bonded to the backbone of the amide modified P.V.C., will form an internally plasticized polymer with the ability to create a network by changing the composition of the materials involved and changing the curing temperature. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 shows a comparison of FTIR analysis before and after aging. 
    
    
     According to the invention there is provided a new composition of matter which is an amide modified P.V.C. (component A), which is reacted with an epoxy resin (component B) either by heating the two components together or by using a catalyst. Specifically, the process of this invention allows the grafting onto the amide modified P.V.C. or other amide modified polymers containing chlorine, the general class of compounds having the formula: ##STR1## resulting in a family of novel modified P.V.C. or other polymers containing chlorine. 
     The reaction between the modified P.V.C. and the oxirane ring compounds is represented by the following scheme: ##STR2## where `n` and `m` may be an integer from 1 to 100. R 3  may be hydrogen, an alkyl group, benzoyl or polyamide. R 5 , R 4 , R 2  and R 1  can be hydrogen, alkyl group or a residue of an epoxy resin. 
     While the above scheme represents the process in accordance with the invention, the preferred reaction is the one wherein R 1  stands for ##STR3## and R 2  stand for hydrogen, thus, component A and component B may be mixed while each one of them is dissolved in a common solvent such as chloroform, tetrahydrofurane, cyclohexanone, etc. 
     Formation of epoxy grafted on P.V.C. via amide pending groups may form a complete spectrum of materials starting from a flexible polymer through a highly crosslinked material with resistance to chemicals and solvents. 
     Among suitable epoxy resins are diglycidyl ether of bisphenol A, such as EPON 828, triglycidyl ether of tris hydroxy phenyl methane and tetraglycidyl of diamino diphenyl methane such as MY-720. 
     EXAMPLES 
     General Procedure 
     (I) Reaction on PVC Suspension 
     A measured amount of suspension or emulsion of polyvinylchloride (Frutarom, Electrochemical Co., Haifa, Israel) in water was continuously stirred and heated on an oil bath. Solvent such as DMF, THF, cyclohexanone or methylethylketone is added to the slurry. While mixing, the sodium or calcium salt of N-butyl-3-mercaptopropionamide was added. At the same time, a small amount of tricaprylyl methyl ammonium chloride (phase transfer catalyst) was added to the reaction mixture. The reaction mixture was kept at 60° C. and from time to time samples were withdrawn from the reaction mixture. The suspension is separated and the polymer is washed several times with distilled water, methanol and ether. The polymer obtained after washing is dissolved in tetrahydrofuran or chloroform and reprecipitated in methanol. The polymer obtained in this way was analyzed for sulfur, nitrogen and chlorine; also NMR and IR of the grafted polymer was taken. 
     The results are summarized in Table 1. 
     
                       TABLE 1                                                     
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The reaction between the sulfur [S] and chlorine [Cl]                     
content on the grafted PVC and the time of reaction*.                     
Time (min)                                                                
          [Cl] %     [S] %   Extent of reaction                           
______________________________________                                    
 30       50.25      1.57    0.0917                                       
 45       49.90      2.06    0.1203                                       
 75       47.30      2.45    0.1432                                       
120       44.75      3.28    0.1922                                       
175       42.65      4.00    0.2337                                       
240       39.20      4.67    0.2729                                       
300       36.95      5.75    0.3360                                       
1295      23.75      9.15    0.5347                                       
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 *The reaction mixture included 80 ml epivyl 43 (˜40% solid content)
 36.8 gr of                                                               
 ##STR4##                                                                 
 10 ml of cyclohexanone, 1 gr of Aliquat, 8.7 gr CaO. The reaction was    
 carried out under argon atmosphere.                                      
 
    
     (II) Reaction on PVC Film or Chlorinated Polyethylene 
     A commercial PVC or chlorinated low density polyethylene was used. The latter film was made by dissolving chlorine gas in CCl 4 , immersion of the film in it and illuminating the reaction mixture with tungsten lamp. 
     The film mentioned above were swirled in water containing the calcium salt of the N-butyl-3-thiopropionamide and a phase transfer catalyst. The results are summarized in Table 2. 
     
                       TABLE 2                                                     
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Grafting of N--butyl 3-thiopropion amide group on films of                
PVC and chlorinated polyethylene immersed in water.                       
            Time of                                                       
Film        reaction Temperature                                          
                                %     %                                   
(50 μm)  (hr)     °C. Sulfur                                    
                                      Chlorine                            
______________________________________                                    
Chlorinated low                                                           
            0        R.T.       0     43.1                                
density polyethylene (28° C.)  44.9                                
Chlorinated low                                                           
            1        56° C.                                        
                                1.6   42.6                                
density polyethylene            1.1   44.2                                
Chlorinated low                                                           
            7        56° C.                                        
                                2.6   32.5                                
density polyethylene            2.5   34.5                                
PVC         1        56° C.                                        
                                4.0   43.5                                
                                      41.1                                
&#34;           7        56° C.                                        
                                11.2  13.1                                
&#34;           50       R.T.       6.0   34.4                                
______________________________________                                    
 
    
     (III) Reactivity of the amide substituted PVC toward epoxy resins 
     Amide substituted PVC and diglycidyl ether of bisphenol A ##STR5## can be dissolved in a common solvent such as THF. A 3% solution of the grafted PVC and EPON 828 epoxy resin was cast to form a clear flexible film. The film was cured at 100° C. for 55 hours. FTIR analysis of the cured film was carried out. A decrease in the absorption of the oxirane functional group at 913 cm -1  has been observed. A comparison between the FTIR spectrum of the film before aging and after it can be seen in FIG. 1. The absorption at 1182 cm -1  which corresponds to the vibration of the C--C bond in the structure ##STR6## was taken as a reference. The ratio between the absorption at 1182 cm -1  and 913 cm -1  increases from 2.86 at room temperature to 7.06 after 55 hours at 100° C., indicating the disappearance of the oxiran structure. On the other hand the absorbance around 3380 cm -1  becomes broader and larger indicating a formation of OH group which might be due to the opening of the oxirane ring. Table 3 represent the extraction experiments carried out on a mixture of amide substituted ##STR7## and Epon 828. The mixtures were cured at 100° C. for 48 hours. 
     
                       TABLE 3                                                     
______________________________________                                    
Extraction experiments of cured epoxy-PVC amide film                      
(curing conditions 48 hrs at 100° C.).                             
                       Moles ratio                                        
                                  **Extracted                             
            *Extracted by                                                 
                       APVC:Epon  by toluene                              
Composition of film                                                       
            THF        828 remain [moles × 10.sup.3 ]               
[moles × 10.sup.3 ]                                                 
            [moles × 10.sup.3 ]                                     
                       in cured film                                      
                                  Epon 828                                
______________________________________                                    
Amide substi-                                                             
tuted PVC                                                                 
(APVC)   4.8    APVC    0.34 1.65                                         
Epon 828 8.5    Epon    5.80           6.3                                
                828                                                       
APVC     4.8    APVC    0.63 1.73                                         
Epon 828 12.8   Epon    10.4          10.2                                
                828                                                       
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 *Sohxlet extracted by boiling THF, 16 hrs.                               
 **The film was swirled in toluene for 7 days at room temperature. The    
 toluene was changed once a day.                                          
 
    
     The extraction experiments indicate that the molar ratio between the amide and the epoxy is about 1.65:1, respectively. That means that approximately one amide group reacts with one epoxy group. The mode of reaction is a follows: ##STR8##