Method of coating conductors with solutions of polyvinyl acetals
This is a division of application Ser. No. 779,550 filed Mar. 21, 1977. 
    
    
     The present invention is directed to certain novel solutions of polyvinyl formal. 
     Polyvinyl formal (Formvar) is normally employed with phenolic solvents as wire enamels for coating magnet wires. 
     These wire enamels have a number of disadvantages. Thus polyvinyl formals must be wet by a hydrocarbon diluent prior to adding the primary solvent. It is possible however, but not practical, to obtain a high concentration of solids, e.g., 16 to 22% solids is the rule in conventional cresylic acid since the viscosity becomes too high above this range, for conventional application. The solvent systems are expensive and the phenolic solvents are toxic and are pollutants. 
     It has now been found that novel solvents comprising certain monoalkyl ethers of diethylene glycol and triethylene glycol or the monophenyl ether of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol or propylene glycol can be used as solvents for polyvinyl formals. In some cases it is necessary to have a diluent, e.g. an aromatic hydrocarbon present as will be discussed hereinafter. 
     Technical Bulletin No. 6070B of Monsanto Polymers and Petrochemicals Co. entitled &#34;Butvar Polyvinyl Butyral, Formvar Polyvinyl Formal, Properties and Uses&#34; shows the solubility properties of Formvar resins. The entire disclosure of the Technical Bulletin No. 6070B is hereby incorporated by reference and relied upon. 
     Bulletin No. 6070B shows that polyvinyl formal with either 68% or 82% formal content is insoluble in Cellosolve (monoethylether of ethylene glycol) while polyvinyl formal with 68% formal content is soluble in Methyl Cellosolve (monomethyl ether of ethylene glycol) but that polyvinyl formal with 82% formal content is not soluble in Methyl Cellosolve. It is not stated what is the concentration at which the solubility was tested but apparently it was quite low since the solubility of various polyvinyl butyrals was tested at either 5% solids or 10% solids depending on the particular polyvinyl butyral. 
     The Technical Bulletin No. 6070B also mentions that polyvinyl formals are soluble in mixtures of alcohols and aromatic hydrocarbons and the viscosity of a 15% solution of various polyvinyl formals in 60:40 toluene-ethanol at 25° C. is recorded. It is further disclosed that solutions of polyvinyl formals show marked increases in viscosity as resin solids increase. In the case of polyvinyl butyral it is disclosed that the solvent can be a mixture of diacetone alcohol, butyl alcohol, 95% ethyl alcohol and either xylene or toluene and that an unspecified part of the diacetone alcohol can be replaced by Cellosolve for lower viscosity. There is not mentioned any combination of a glycol monoether with another solvent for dissolving polyvinyl formals, which are more difficult to dissolve than polyvinyl butyrals. 
     The specific ether solvents with which the present invention is concerned are the monomethyl ether of diethylene glycol (Methyl Carbitol), the monoethyl ether of diethylene glycol (Carbitol), the monomethyl ether of triethylene glycol, the monoethyl ether of triethylene glycol, the monophenyl ether of ethylene glycol, the monophenyl ether of diethylene glycol, the monophenyl ether of triethylene glycol, the monophenyl ether of tetraethylene glycol, and the monophenyl ether of propylene glycol. The polyvinyl formals are only soluble in the monophenyl ether of ethylene glycol alone, the monophenyl ether of diethylene glycol alone, the monophenyl ether of triethylene glycol, the monophenyl ether of tetraethylene glycol, or the monophenyl ether of propylene glycol (or in a mixture of these monophenyl ethers). 
     The suitable monoalkyl ethers can be expressed by the formula 
     
         R.sub.1 O(C.sub.2 H.sub.4 O).sub.x H                       I 
    
     where R 1  is alkyl of 1 to 2 carbon atoms and x is 2 or 3. 
     The suitable phenyl ethers can be expressed by the formula 
     
         R.sub.2 O(C.sub.n H.sub.2n O).sub.y H                      II 
    
     where R 2  is phenyl, and y is 1, 2, 3, or 4 and n is 2 or 3. 
     The compounds of formula I must be used with a diluent while the compounds of formula II can be used alone or with a diluent. 
     The amount of diluent will vary depending on the diluent and the solids concentration desired. In general with the compounds of formula I there is used 10 to 95% of the compound and 90 to 5% of the diluent. (The same amount of diluent can be used, if desired, with the compounds of formula II and in addition to the diluents mentioned below there can also be used the compounds of formula I as diluents for the compounds of formula II, the compounds of formula I being less expensive than those of formula II.) 
     The proportions of the compound of formula I (or formula II) and diluent should be such as to provide a solution of polyvinyl formal having at least 20% solids and more preferably 25 to 35% solids, most preferably at least 30% solids. 
     Some of the formulations have the desired concentrations, both in the cold, e.g., at 77° F. (25° C.) or hot, e.g., at 140° F. (60° C.) or above while other formulations can only be used hot. The preferred formulations are those which impart the desired solubility of at least 20% solids, more preferably at least 25% solids in the cold since they have the broadest range of application. 
     For hot melt and extrusion work the temperature can be raised, e.g., to 120°-140° C. and the solids can be as high as 70% or even higher. The limiting factor in solids content is the viscosity which can be tolerated by the equipment. 
     As diluents there are especially preferred aromatic hydrocarbons such as benzene, toluene, xylene, ethyl benzene and other alkylated benzenes, alkylated naphthalenes. There can be present a minor amount of aliphatic hydrocarbons in the aromatic hydrocarbon. In the event that the hydrocarbon mixture does not sufficiently dissolve in the compound of formula I or II in the cold there can be added enough xylene or toluene (or even cyclohexanone) to render it more soluble. Examples of mixtures of hydrocarbons are enamel wire naphtha, Solvesso 100 (an aromatic naphtha, primarily monoalkyl benzenes, boiling in the range of 315°-350° F.), Solvesso 150 (a heavy aromatic naphtha which is primarily a mixture of tetramethyl benzene with dialkyl and trialkyl benzenes boiling in the range 360°-400° F.), a blend of 70% Solvesso 150 with 30% heavy aromatic naphtha (the blend being known as Solvesso N-150 and having a boiling range of 372°-500° F.), W.E.S. oil (a blend of aromatic hydrocarbons which distills 10% to not below 165° C., 70% to not above 190° C. and 95% to not above 235° C.). W.E.S. oil is an example of an enamel wire naphtha. Solvesso 100 can be used with the ethers of formula I in the hot but in the cold it is necessary to add xylene (or toluene) to get the desired solubility. Solvesso 150 can be blended with the ethers of formula I hot but not cold. 
     Other diluents include Cellosolve, Cellosolve acetate (ethoxyethyl acetate), lower alkyl acetates, e.g., methyl acetate, ethyl acetate, lower alkanols, such as those having 1 to 3 carbon atoms, e.g., methyl alcohol, ethyl alcohol, isopropyl alcohol, ketones including lower alkanones, e.g., acetone, methyl ethyl ketone and methyl isobutyl ketone, cyclohexanone, Butyl Carbitol (butyl ether of diethylene glycol), Hexyl Carbitol (hexyl ether of diethylene glycol). The alkanols were only useful with the compounds of formula II as diluents in polyvinyl formal enamels. 
     Propasol DM solvent (monomethyl ether of dipropylene glycol) can also be used as a diluent together with the aromatic solvent to give a composition in which the polyvinyl formal is soluble in the hot. 
     The wire enamels of the present invention can have the conventional additives employed in coating magnet wire and other electrical conductors. Thus there can be employed phenolic resins, e.g., phenol-formaldehyde resins, such as p-phenylphenol-formaldehyde, meta-para cresol-formaldehyde, phenol-formaldehyde, alkylphenol-formaldehyde resins. There can also be added conventional blocked isocyanates, e.g., the reaction product of glycerine and toluene diisocyanate blocked with phenol, the reaction product of diethylene glycol and trimethylol propane with toluene diisocyanate blocked with phenol Mondur S (butylene glycol and trimethylol propane with toluene diisocyanate blocked with a phenol), trimethylol propane and 1,3-butylene glycol reacted with toluene diisocyanate blocked with phenol. Other conventional additives such as polyesters or resimenes may be added. 
     Examples of suitable polyvinyl formals (all are free flowing powders) are those set forth below. The properties are taken from Technical Bulletin No. 6070B. 
     
         __________________________________________________________________________
             Type of Formvar                                              
Property  Units                                                           
             12/85  5/95   6/95   7/95   15/95E                           
__________________________________________________________________________
Volatiles, max.                                                           
          %  1.5    1.5    1.0    1.0    1.0                              
Molecular wt.                                                             
             26,000-34,000                                                
                    10,000-15,000                                         
                           14,000-17,000                                  
                                  16,000-20,000                           
                                         24,000-40,000                    
(weight average)                                                          
Solution Viscosity                                                        
          cp 500-600                                                      
                    100-200                                               
                           200-300                                        
                                  300-500                                 
                                         3000-4500                        
15% by wt. in 60:40                                                       
toluene-ethanol at                                                        
25° C.                                                             
Hydroxyl content                                                          
             5.5-7.0                                                      
                    5.0-6.5                                               
                           5.0-6.5                                        
                                  5.0-6.5                                 
                                         5.0-6.0                          
expressed as %                                                            
polyvinyl alcohol                                                         
Acetate content                                                           
             22-30  9.5-13.0                                              
                           9.5-13.0                                       
                                  9.5-13.0                                
                                         9.5-13.0                         
expressed as %                                                            
polyvinyl acetate                                                         
Formal content                                                            
             68     82     82     82     82                               
expressed as %                                                            
polyvinyl formal                                                          
approx.                                                                   
__________________________________________________________________________
 
    
     The solvent systems of the invention are particularly useful with the polyvinyl formals of relatively high formal content, e.g., 82%, which are normally most difficult to dissolve in solvents and which are the most important polyvinyl formals for use as wire coating. 
     Unless otherwise indicated all parts and percentages are by weight. 
     The compositions of the invention can comprise, consist essentially of or consist of the materials set forth. 
     The wire enamels can be applied to copper, silver, aluminum or other wires using conventional coating procedures and wire speeds and temperatures, e.g., 400° to 800° F. In the working examples the temperature of application to the wire was 140° F. and the wire speed was 45 ft/min. 
     In place of the Carbitol materials there of course can be used the same solvents sold under other trademarks such as Dowanol. 
     There is no problem in determining whether any particular combination of solvent and diluent is suitable. All that is necessary is to mix the solvent and diluent and add polyvinyl formal at the desired concentration and heat to 60° C. to see if solution occurs. To determine whether the polyvinyl formal is soluble at 25° C. the solution is then cooled to 25° C. (If the polyvinyl formal is not soluble in the hot mixture there is no need to test its solubility in the cold as it will not be soluble. 
     The novel solvent systems of the invention have the following advantages over the present day commercial phenolic solvent containing wire enamels: 
     1. The polyvinyl formal powder does not need to be wet by a hydrocarbon diluent prior to the addition of the primary solvent. 
     2. The final coatings are at much higher percentage solids, e.g., 25-35%, and when heated to application temperature have lower viscosities than those of equal solids in conventional solvent systems. 
     3. The current conventional solvent systems are more expensive. 
     4. The new glycol ether (formula I or formula II) based solvent systems are less toxic than the conventional phenol, cresol and xylenol based solvent systems. Thus, the end result is that the polyvinyl formal solutions in glycol ether based solvent systems of the invention are more readily processed, handled and ecologically advantageous. 
     As previously pointed out, except for the phenyl glycol ethers of formula II, the polyvinyl formal powders used are not soluble in the component parts of the systems described. However, when the component parts are blended, the polyvinyl formal is readily dissolved and forms a stable, clear solution at room temperature (or in some cases only at elevated temperature). 
    
    
     EXAMPLE I 
     
         ______________________________________                                    
Reactant              Batch Weight, Grams                                 
______________________________________                                    
1.  Solvesso 100          162                                             
2.  Xylol                 162                                             
3.  7/95E Formvar Powder  260                                             
4.  Methyl Carbitol       158                                             
5.  Ethyl Carbitol        214                                             
6.  Phenolic Resin I in Methyl Carbitol*                                  
                          270                                             
7.  Blocked Isocyanate I**                                                
                          28.6                                            
8.  Xylol                 18                                              
9.  Solvesso 100          18                                              
10. Methyl Carbitol       24                                              
11. Ethyl Carbitol        24                                              
______________________________________                                    
 *Phenolic Resin I is the reaction product of meta para cresol and        
 formaldehyde and is at 41.5 percent solids in methyl carbitol.           
 **Blocked isocyanate I is made from diethylene glycol and trimethylol    
 propane with toluene diisocyanate and blocked with phenol.               
 
    
     Parts one through five were charged into a three liter reaction kettle equipped with an agitator, thermometer and condenser. The batch was heated to 70° C. and held until three was all dissolved. Parts 6 through 11 were then added. The reaction temperature dropped during the addition to 60° C. The reaction mixture was held for one hour at this temperature then filtered through a paper cone. The viscosity of this mixture at 140° C. was 3375 cps. The percent solids as determined at two grams for two hours at 400° F. was 31.2 percent. 
     A 3.2 mil coating of this material was applied to 18AWG copper wire. The coated wire had a good appearance. The properties are as shown in Table I. 
     A similar wire enamel solution was held for two weeks at 130° F. The only changes observed were a darkening of the reaction mixture&#39;s color and very slight advance in viscosity from 3375 centipoises to 3500 centipoises. 
     A viscosity study conducted in an open pot at 140° F. on the product of Example I showed an increase in viscosity of 4000 centipoises over a seven hour time span. The initial increase from 3750 centipoises to 7375 centipoises took only one and one half hours. The solution viscosity remained relatively stable thereafter, advancing only 275 centipoises in the next five and one half hours. In contrast similar conventional systems with phenolic solvents have also shown an inital doubling of viscosity, however upon prolonged holding at elevated temperatures the viscosity continued to advance exponentially. 
     EXAMPLE II 
     
         ______________________________________                                    
Reactant              Batch Weight, Grams                                 
______________________________________                                    
1.  Solvesso 100          139                                             
2.  Xylol                 139                                             
3.  7/95E Formvar Powder  130                                             
4.  Methyl Carbitol       262                                             
5.  Phenolic Resin I 40% Solution                                         
                          145                                             
     in Cresylic Acid                                                     
6.  Blocked Isocyanate II*                                                
                          33.6                                            
7.  Solvesso 100          6                                               
8.  Xylol                 6                                               
9.  Methyl Carbitol       17                                              
______________________________________                                    
 *Blocked isocyanate II is the reaction product of glycerine and toluene  
 diisocyanate blocked with phenol and is dissolved at 40 percent solids in
 cresylic acid.                                                           
 
    
     The blending procedure was carried out as stated in Example I with parts 1 through 4 being charged then heated slightly to aid in dissolving 3. When 3 was dissolved in the solvents, the rest of the materials were added and blended into the solution thoroughly prior to filtration. 
     The percent solids determined by baking three grams for one half hour at 400° F. were 21.6 percent. 
     The viscosity determined on the Gardner-Holdt scale at 77° F. was Z2 3/4. 
     The solution was applied to 18 AWG copper wire and tested as a magnet wire coating. A 2.9 mil build was obtained at 45 feet per minute with good appearance. The electrical test properties are as shown in Table I. 
     EXAMPLE III 
     
         ______________________________________                                    
Reactant              Batch Weight, Grams                                 
______________________________________                                    
1.  Solvesso 100          162                                             
2.  Xylol                 162                                             
3.  7/95E Formvar Powder  260                                             
4.  Methyl Carbitol       158                                             
5.  Ethyl Carbitol        214                                             
6.  Phenolic Resin I in Methyl Carbitol                                   
                          270                                             
     (40-42% solids)                                                      
7.  Xylol                 18                                              
8.  Solvesso 100          18                                              
9.  Methyl Carbitol       24                                              
10. Ethyl Carbitol        24                                              
______________________________________                                    
 
    
     This coating was blended as described in Example I. 
     The viscosity at 140° F. was determined to be 3700 centipoises. 
     The solids were 28.4 percent. 
     When used to coat 18 AWG copper wire this enamel gave a 2.8 mil build at 45 fee per minute. The appearance was rated as good. Other test results are shown in Table I. 
     EXAMPLE IV 
     
         ______________________________________                                    
Reactant              Batch Weight, Grams                                 
______________________________________                                    
1.  Solvesso 100          13.9                                            
2.  Xylol                 13.9                                            
3.  7/95E Formvar         13.0                                            
4.  Methyl Carbitol       29.2                                            
5.  Phenolic Resin I in Methyl Carbitol                                   
                          13.5                                            
     (40-42%)                                                             
6.  Blocked Isocyanate I  1.5                                             
7.  Xylol                 0.6                                             
8.  Solvesso 100          0.6                                             
9.  Methyl Carbitol       1.7                                             
______________________________________                                    
 
    
     The batch was blended as in Example One. 
     The viscosity was 2500 cps at 130° F. 
     The solids were calculated to be 21.2 percent. 
     This batch when cooled had a very slight haze which did not worsen after standing at room temperature for 24 hours. This haze disappeared upon very slight heating. 
     EXAMPLE V 
     
         ______________________________________                                    
Reactant              Batch Weight, Grams                                 
______________________________________                                    
1.  Solvesso 100          13.9                                            
2.  Xylol                 13.9                                            
3.  7/95E Formvar Powder  13.0                                            
4.  Ethyl Carbitol        29.2                                            
5.  Phenolic Resin I in Methyl Carbitol                                   
                          13.5                                            
     (40-42% Solids)                                                      
6.  Blocked Isocyanate I  1.5                                             
7.  Xylol                 0.6                                             
8.  Solvesso 100          0.6                                             
9.  Ethyl Carbitol        1.7                                             
______________________________________                                    
 
    
     The batch was blended as in Example I. 
     The percent solids was 21.2 percent. 
     The batch was soluble hot, and remained in solution upon cooling for a short period. However, upon leaving the batch sit in a covered container over night, it became cloudy. 
     EXAMPLE VI 
     Butyl Carbitol was tried in a blend as in Examples IV and V (i.e., it replaced the Methyl Carbitol or Ethyl Carbitol) and was insoluble hot and at room temperature. 
     EXAMPLE VII 
     Examples IV and V were blended together in equal portions to produce a clear stable solution, with a viscosity of 2475 centipoises at 130° F. and 21.2 percent solids. 
     EXAMPLE VIII 
     To Example VII enough of Example VI was added to produce a solvent system containing 40 percent Methyl Carbitol, 40 percent Ethyl Carbitol and 20 percent Butyl Carbitol based on the total Carbitols. The solution remained clear at room temperature. 
     When enough of Example VI was added to Example VII to give equal portions of methyl, ethyl and butyl Carbitols in the solvent system, the mixture became insoluble. 
     
         ______________________________________                                    
Ingredient            Batch Weight, Gram                                  
______________________________________                                    
6/95E Formvar Powder  10                                                  
Methyl Carbitol       12                                                  
Ethyl Carbitol        12                                                  
Diluent               16                                                  
Only the diluents are listed in Table II.                                 
______________________________________                                    
 
    
     A series of diluents were tried in determining the scope of the invention. In Table II are representative examples of several classes of compounds and their effects on the polyvinyl formal solvent system. 
     All solutions were compounded at 20 percent calculated solids using 6/95E Formvar Powder at 15 centipoises. The solvent system contained 30 percent Methyl Carbitol, 30 percent Ethyl Carbitol and 40 percent of the diluent of choice. The standard formula used therefore read: 
     
         ______________________________________                                    
Ingredient            Batch Weight, Grams                                 
______________________________________                                    
6/95E Formvar Powder  10                                                  
Methyl Carbitol       12                                                  
Ethyl Carbitol        12                                                  
Diluent               16                                                  
Only the diluents are listed in Table II.                                 
______________________________________                                    
 
    
     
                       Table II                                                    
______________________________________                                    
           Soluble   Soluble                                              
           Hot       Cold      Viscosity                                  
Diluent    (140° F.)                                               
                     (77° F.)                                      
                               at 130° F.                          
______________________________________                                    
Solvesso 150                                                              
           Yes       No        Not Determined                             
Heavy      Yes       No        Not Determined                             
Aromatic                                                                  
Naphtha                                                                   
Solvesso N-150                                                            
           Yes       No        Not Determined                             
Solvesso 100                                                              
           Yes       Slightly  Not Determined                             
W.E.S. Oil Yes       Yes       2625 centipoises                           
Xylol      Yes       Yes       2075 centipoises                           
Toluene    Yes       Yes       Not Determined                             
Cellosolve Yes       No        Not Determined                             
Cellosolve Yes       No        Not Determined                             
Acetate                                                                   
Ethyl      Yes       No        Not Determined                             
Acetate                                                                   
Ethyl Alcohol                                                             
           No        No        Not Determined                             
Methyl     No        No        Not Determined                             
Alcohol                                                                   
Isopropyl  No        No        Not Determined                             
Alcohol                                                                   
Acetone    Yes       Yes*      Not Determined                             
Cyclohexanone                                                             
           Yes       Yes       2502.5 centipoises                         
Methyl     Yes       No        Not Determined                             
Ethyl                                                                     
Ketone                                                                    
Methyl     Yes       No        Not Determined                             
Isobutyl                                                                  
Ketone                                                                    
______________________________________                                    
 *Upon standing a white layer formed on the top of the container where the
 acetone evaporated off.                                                  
 
    
     Table III lists other various solvent systems tried and the results obtained. All the reactions were compounded at 20 percent calculated solids. 
     
                                           Table III                               
__________________________________________________________________________
            Percent                                                       
       Batch                                                              
             of  Soluble                                                  
                      Soluble                                             
                           Viscosity                                      
       Weight                                                             
            Solvent                                                       
                 Hot  Cold at                                             
Formula                                                                   
       in Grams                                                           
            System                                                        
                 (140° F.)                                         
                      (77° F.)                                     
                           130° F.                                 
__________________________________________________________________________
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Methyl 12   30                                                            
Carbitol                                                                  
Ethyl  12   30   Yes  Yes  2550 centipoises                               
Carbitol                                                                  
Solvesso                                                                  
       8    20                                                            
100                                                                       
Xylol  8    20                                                            
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Methyl 12   30                                                            
Carbitol                                                                  
Ethyl  12   30   Yes  Yes  2600 centipoises                               
Carbitol                                                                  
Solvesso                                                                  
       12   30                                                            
100                                                                       
Xylol  4    10                                                            
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Hexyl  24   60   Yes  No   Not Determined                                 
Carbitol                                                                  
Solvesso                                                                  
       8    20                                                            
100                                                                       
Xylol  8    20                                                            
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Hexyl  12   30                                                            
Carbitol                                                                  
Methyl 12   30   Yes  No   Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
695E   10   --                                                            
Formvar                                                                   
Powder                                                                    
Propasol                                                                  
       24   60                                                            
DM Solvent                                                                
Xylol  8    20   No   No   Not Determined                                 
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Propasol                                                                  
       12   30                                                            
DM Solvent                                                                
Methyl 12   30   Yes  No   Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Phenyl 24   60                                                            
Glycol                                                                    
Ethers*                                                                   
Xylol  8    20   Yes  Yes  Not Determined                                 
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Phenyl 12   30                                                            
Glycol                                                                    
Ethers*                                                                   
Methyl 12   30   Yes  Yes  Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Ethoxy 24   60   Yes  No   Not Determined                                 
Triethylene                                                               
Glycol                                                                    
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Ethoxy 12   30                                                            
Triethylene                                                               
Glycol                                                                    
Methyl 12   30   Yes  Yes  Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Ethoxy 12   30                                                            
Triethylene                                                               
Glycol                                                                    
Methyl 12   30   Yes  Yes  Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Methoxy                                                                   
       24   60   Yes  Yes  Not Determined                                 
Triethylene                                                               
Glycol                                                                    
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Methoxy                                                                   
       12   30                                                            
Triethylene                                                               
Glycol                                                                    
Methyl 12   30   Yes  Yes  Not Determined                                 
Carbitol                                                                  
Xylol  8    20                                                            
Solvesso                                                                  
       8    20                                                            
100                                                                       
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Phenyl 40   100  Yes  Yes  Not Determined                                 
Glycol                                                                    
Ethers*                                                                   
6/95E  10   --                                                            
Formvar                                                                   
Powder                                                                    
Phenyl 30   50   Yes  Yes  Not Determined                                 
Glycol                                                                    
Ethers*                                                                   
Ethyl  30   50   Yes  Yes  Not Determined                                 
Alcohol                                                                   
6/95E  10   --                                                            
Formvar                                                                   
Powder           Yes  Yes  Not Determined                                 
Dowanol                                                                   
PPH*** 40   100                                                           
T4Ph**                                                                    
6/95E  10   --                                                            
Formvar                                                                   
Powder           Yes  Yes  Not Determined                                 
Dowanol                                                                   
       40   100                                                           
PPH***                                                                    
6/95E  10   --                                                            
Formvar                                                                   
Powder           Yes  Yes  Not Determined                                 
Dowanol                                                                   
       30   50                                                            
T4Ph**                                                                    
Ethyl  30   50                                                            
Alcohol                                                                   
6/95E  10   --                                                            
Formvar                                                                   
Powder           Yes  Yes  Not Determined                                 
Dowaol 30   50                                                            
PPh***                                                                    
Ethyl  30                                                                 
Dowanol                                                                   
Alcohol                                                                   
__________________________________________________________________________
 *Phenyl Glycol Ethers -- A blend of 70 percent ethylene glycol monophenyl
 ether and 30 percent diethylene glycol monophenyl ether.                 
 
    
     From Table III it is clear that Methoxy Triethylene Glycol compares to Methyl Carbitol as does Ethoxy Triethylene Glycol to Ethyl Carbitol. 
     Also from Table III it is obvious that the Phenyl Glycol Ethers are good solvents for Formvar. Not only was the 6/95E Formvar Powder soluble in straight phenyl glycol ethers, but an equal amount of Ethyl Alcohol was added without precipitating out the Formvar solution. With Methyl Carbitol a diluent is needed and the Formvar powder is precipitated by even a slight addition of Ethyl Alcohol. Similar results were obtained when the phenyl ether of tetraethylene glycol and the phenyl ether of propylene glycol were used, as shown in Table III.