Patent Publication Number: US-4321092-A

Title: Pressure-sensitive duplicating material

Description:
This is a continuation, of application Ser. No. 887,519, filed Mar. 17, 1978 which in turn was a continuation of Ser. Nos. 688,759 and 485,434 filed May 21, 1976 and July 3, 1974 respectively and all abandoned. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention is concerned with pressure-sensitive carbon-copying materials, also known as chemical copying papers, such copying papers commonly being provided with a color-forming coating and a color substance-accepting coat. Under pressure, part of the color-former reacts with the color-substance acceptor under local discoloration. 
     Such copy papers contain, in most cases, organic compounds which are enclosed in micro-capsules, and which are commonly known as color-formers since, in combination with color-substance acceptors, they produce a color-reaction. Such color formers include, for example, crystal violet lactone, malachite green lactone, benzoyleucomethylene blue, rodamin beta lactume or leucoauramine. Color substance acceptors which are presently in use include, for example, those having a base of attapulgite, zeolite, kaolin, phenol resins, as well as phenol compounds with freely reacting phenol groups in combination with binding agents. Such binding agents may include, for example, polyvinyl, polyvinyl chloride and polyvinyl acetate compounds and mixed polymerizates of these compounds and resins, for example, ester-derivatives of colophony and alcohol, as well as metal stearates and silicic acid. Commonly, the color-formers and color-substance acceptors are present in separate layers. Such a paper may, however, also comprise a sheet which contains color-forming agents as well as color-substance acceptors, possibly with an intermediate layer. Under pressure, a part of the color-former reacts with the color-substance accepting-mass under local discoloration. 
     It has been found that the color-substance acceptor masses which are utilized in chemical copying papers can be improved in many respects by adding to these masses chlorides of metal salts, sometimes in combination with urea or urea-derivatives as the chief reacting components. 
     The utilization of metal chlorides will result in an intensive color formation which is characterized by a special light-stability, so that this color formation is obtained with color-forming coats which are not as thick as the acceptor-layers, in which are present predominantly the common color-substance acceptors, such as attapulgite or kaolin. 
     Accordingly, the present invention is concerned with a pressure-sensitive copying material based on a color-forming mass and a color-substance accepting mass which reacts when coming in contact with said color-forming mass to produce color, and characterized in that the color-substance accepting mass contains as reaction components a chloride of a metal having an atomic weight of from 50-66, the metal preferably being zinc, vanadium, chromium, manganese, iron, cobalt, nickel or copper, possibly in combination with urea or its derivatives, for example thiocarbamine. Also present are a binding agent and other additives. The metal salt is bound to the base material directly in combination with the binding agent, and the color-forming mass comprises an initial dyestuff product which is also combined directly with the binding agent, and which reacts with the color-substance acceptor during color-formation. 
     The color-substance accepting mass can be applied to the base with the aid of a solvent in which the metal chloride, or the combination metal-chloride and urea which is to be used, or a derivative thereof, is insoluble, or is applied also in the form of a fluid solution. In the latter case, the metal-chloride, or the combination to be utilized, may be dispersed in wax and applied at a temperature of from 50°-220° C. The waxes which may be utilized may be vegetable, animal- or mineral-waxes, synthetic and chlorinated waxes, as well as paraffins, oxide-waxes, polyethylene- and polyethylene-oxide waxes having a molecular weight of 400-12000. 
     In the application of the solvent, there may be used aliphatic hydrocarbons, chloro-hydrocarbons, aromatic hydrocarbons, alcohols, esters or ketones. 
     Additionally, suitable binding agents for the coating application are polyvinyl-, polyvinyl chloride- and polyvinyl acetate compounds, or a mixed polymerizate of these compounds to which may be added softening agents, metal stearates such as cobalt or zinc stearates, natural resins or additional synthetic resins, and conditionally active or inactive clay, for example kaolin or silicic acid. As urea derivatives, one may utilize thiocarbamine or any random derivative of the common formula: 
     
         C.sub.p H.sub.4 +.sub.q R 
    
     in which 
     p=1-20, q=1-16 and, 
     R=a member of the group N 2  O, N 2  O 2 , N 2  S or N 4  O 3 , or a complex compound with halogen, especially a trifluoride or trichloride urea complex compound. 
     Urea as well as thiocarbamine, and especially diphenylthiocarbamine should be mentioned as an additive for the metal chloride. 
     It has also been noted that the addition of a metal stearate or a mixture of acid and alcohol on an acetylene base with cycloaliphatic N- or O-containing condensation-products results in an intensification of the color reaction. As to the stearates utilized in the copying materials of the present invention, in addition to the cobalt and zinc stearates, there may also be utilized stearates of lead, tin, calcium, aluminum, barium or iron. 
     It is common in the prior art to also add metal salts to the color-substance accepting masses. However, these components should be added only in small quantities, in order to accelerate the color-format ion and not for the purpose of producing the actual color-reaction. In the present compositions, the metal salts, especially the zinc-chloride or the combination of zinc-chloride and urea or its derivatives, are added in an amount of about 5-90% in weight. The ratio of the mixture of metal chloride and urea or its derivatives should preferably be from about 5:1 to 1:1. 
     Zinc chloride is especially suitable as the metal chloride. However, excellent color-intensive and color-stable copies are also obtained with other chloride such as, for example, chromium (III) chloride, manganese (II) chloride, iron (III) chloride, nickel (II) chloride, cobalt (II) chloride or copper (II) chloride. 
     In the case where zinc chloride and urea are utilized for the color-substance accepting mass, a ratio of these substances of about 9:1 to 1:5 is advantageously employed. 
     The present invention produces not only the advantage of obtaining the above listed color-intensive and color-true transfer pictures, but it also produces the possibility for applying the color-substance accepting mass in a substantially thinner coating than has been formerly possible. The color-substance accepting mass may be applied in a quantity of from 2-5 g/m 2 . It is, however, a special effect of the present invention that an application of only 0.5-6 g/m 2 , preferably 0.3-4 g/m 2  suffices, without causing a reduction of the quality of the copies. Such thin layers of application result in the advantage that substantially more sheets may be used in a set of copying-papers than was formerly possible. The preferred thickness of application depends on the type of the coating method or on the type of the solution- or dispersing-material used. If water is utilized as the dispersing-agent, then the applied coats are somewhat thicker than in the use of organic solvents, such as acetone or ethyl alcohol. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In Table No. 1 hereinbelow are summarized comparison tests in accordance with the present inventive process. The color-former consisted of two parts crystal violet lactone and one part benzoyleucomethylene blue. The color-substance accepting mass contained: 
     1=attapulgite+binding agent 
     2=zinc chloride+binding agent 
     3=urea+binding agent 
     4=attapulgite+zinc chloride+binding agent 
     5=attapulgite+urea+binding agent 
     6=zinc chloride+urea+binding agent 
     7=zinc chloride+urea+metal stearate+binding agent 
     8=zinc chloride+urea+metal stearate+attapulgite+binding agent 
     The coating thickness was 2 to 2.5 g/m 2 , and acetone or water was used as an application medium. 
     
                       TABLE NO. 1                                                 
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Reaction Intensity                                                        
Mass Acetone            H.sub.2 O                                         
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1    almost no reaction very weak reaction                                
2    reaction color too light                                             
                        good reaction                                     
3    no reaction        no reaction                                       
4    reaction as in 2   reaction as in 2                                  
5    reaction as in 1   reaction as in 1                                  
6    substantially stronger                                               
                        very strong reaction,                             
     reaction as in 1 to 5                                                
                        better than in 1 to 5                             
7    reaction more intensive                                              
                        reaction more intensive                           
     than in 6          than in 6                                         
8    no improvement in  no improvement in                                 
     reaction over 7    reaction over 7                                   
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     From the foregoing Table No. 1, it may be noted that with a color substance accepting mass which, according to the present invention, contains zinc chloride and urea as the reaction components, substantially better results were obtained than with masses which do not contain these reaction-components. These results can be improved somewhat when, in addition to the foregoing combination, masses are used which also contain metal stearate. The stearates utilized in the present inventive copying papers are, for example, lead-, zinc-, calcium-, aluminum-, barium-, and iron-stearate. 
     The examples listed below contain the color-substance acceptor masses and color-formers utilized in the present inventive copying material, whereby in the utilization of masses which are applied with the help of a solvent, the respective solvent is also mentioned. 
     
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EXAMPLES FOR COLOR-SUBSTANCE ACCEPTOR-MASSES:                             
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1.  Oxocerite                  80 parts                                   
    polyethylene wax           20 parts                                   
    mixture of an acid amide and an alcohol on                            
    acetylene base with cycloaliphatic N- and                             
    O-containing condensation products                                    
                               5 parts                                    
    zinc chloride              25 parts                                   
    thickness of application - 2.8 g/m.sup.2                              
2.  carnuba wax                60 parts                                   
    micro wax                  15 parts                                   
    polyethylene wax           15 parts                                   
    mixture of an acid amide and alcohol on                               
    acetylene base with cycloaliphatic N-                                 
    and O-containing condensation products                                
                               6 parts                                    
    O-containing condensation products                                    
                               6 parts                                    
    zinc chloride              20 parts                                   
    urea                       8 parts                                    
    thickness of application - 3.5 g/m.sup.2                              
3.  carnauba wax               80 parts                                   
    paraffin                   30 parts                                   
    colophonic resin           6 parts                                    
    polyethylene               12 parts                                   
    zinc chloride              30 parts                                   
    mixture of an acid amide and alcohol on                               
    acetylene base with cycloaliphatic N-                                 
    and O-containing condensation products                                
                               3 parts                                    
    thickness of application - 3 g/m.sup.2                                
4.  zinc chloride              15 parts                                   
    polyterpene resin          3 parts                                    
    calcium carbonate          10 parts                                   
    zinc stearate              3 parts                                    
    polyethylene wax           1 part                                     
    thiocarbamine              5 parts                                    
    acrylic resin              5 parts                                    
    benzene                    90 parts                                   
    thickness of application - 3.6 g/m.sup.2                              
5.  zinc chloride              20 parts                                   
    phthalic acid ester of technical                                      
    hydroabietic alcohol       5 parts                                    
    titanium dioxide           10 parts                                   
    urea                       7 parts                                    
    calcium stearate           2 parts                                    
    polyethylene wax           5 parts                                    
    polystyrene                4 parts                                    
    trichloroethylene          80 parts                                   
    thickness of application - 3.8 g/m.sup.2                              
6.  zinc chloride              25 parts                                   
    urea                       10 parts                                   
    stockalite                 20 parts                                   
    calcium stearate           6 parts                                    
    dibutylphthalate           3 parts                                    
    polyvinyl alcohol          3 parts                                    
    water                      85 parts                                   
    thickness of application - 4 g/m.sup.2                                
7.  zinc chloride              15 parts                                   
    thiocarbamine              5 parts                                    
    zinc stearate              5 parts                                    
    acrylic butyral dispersion 2 parts                                    
    kaolin (China clay)        20 parts                                   
    H.sub.2 O                  90 parts                                   
    thickness of application - 1.9 g/m.sup.2                              
8.  zinc chloride              9 parts                                    
    attapulgite                5 parts                                    
    zinc stearate              5 parts                                    
    kaolin                     5 parts                                    
    polyvinyl acetate          6 parts                                    
    maleic acid modified pentaerythrite                                   
    colophonic ester           3 parts                                    
    acetone                    120 parts                                  
    thickness of application - 1.7 g/m.sup.2                              
9.  zinc chloride              12 parts                                   
    attapulgite                3 parts                                    
    lead stearate              5 parts                                    
    calcium carbonate          5 parts                                    
    phthalic acid ester of technical                                      
    hydroabietic alcohol       6 parts                                    
    vinylchloride acetate copolymer                                       
                               10 parts                                   
    methylethyl ketone         80 parts                                   
    thickness of application - 2 g/m.sup.2                                
10. zinc chloride              8 parts                                    
    attapulgite                2 parts                                    
    calcium stearate           6 parts                                    
    modified pentaerythrite ester                                         
                               8 parts                                    
    polystyrene                1 part                                     
    vinyl acetate              5 parts                                    
    acetone                    90 parts                                   
    trichloroethylene          10 parts                                   
    thickness of application - 1.4 g/m.sup.2                              
11. zinc chloride              15 parts                                   
    attapulgite                5 parts                                    
    polyvinylbutyrol           3 parts                                    
    zinc stearate              10 parts                                   
    titanium dioxide           10 parts                                   
    glycerin ester of polymerized colophony                               
                               5 parts                                    
    ethyl alcohol              100 parts                                  
    thickness of application - 0.9 g/m.sup.2                              
12. zinc chloride              20 parts                                   
    attapulgite                5 parts                                    
    calcium stearate           5 parts                                    
    kaolin                     10 parts                                   
    polyvinyl alcohol          5 parts                                    
    water                      150 parts                                  
    thickness of application - 3.5 g/m.sup.2                              
13. zinc chloride              12 parts                                   
    urea                       4 parts                                    
    vinyl acetate              1 part                                     
    phthalic acid ester of technical                                      
    hydroabietic alcohol       2 parts                                    
    acetone                    80 parts                                   
    thickness of application - 2 g/m.sup.2                                
14. Iron (III)-chloride        15 parts                                   
    urea                       4 parts                                    
    vinyl acetate              1 part                                     
    phthalic acid ester of technical                                      
    hydroabietic alcohol       2 parts                                    
    acetone                    80 parts                                   
    thickness of application - 2.2 g/m.sup.2                              
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     In place of iron (III)-chloride, there may be employed chromium (III)-chloride, vanadium (III)-chloride or manganese (III)-chloride. 
     
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15.  zinc chloride             16 parts                                   
     diphenyl thiocarbamine    6 parts                                    
     polyvinyl alcohol         1.5 parts                                  
     calcium stearate          5 parts                                    
     H.sub.2 O                 90 parts                                   
     thickness of application - 4.3 g/m.sup.2                             
16.  nickel (II)- or cobalt (II)-chloride                                 
                               18 parts                                   
     diphenyl thiocarbamine    6 parts                                    
     polyvinyl alcohol         1.5 parts                                  
     calcium stearate          5 parts                                    
     H.sub.2 O                 90 parts                                   
     thickness of application - 4.4 g/m.sup.2                             
17.  zinc chloride             15 parts                                   
     urea                      10 parts                                   
     polyvinyl butyral         3 parts                                    
     modified pentaerythrite ester                                        
                               2 parts                                    
     calcium carbonate         10 parts                                   
     zinc stearate             4 parts                                    
     ethyl alcohol             120 parts                                  
     thickness of application - 0.9 g/m.sup.2                             
18.  zinc chloride             20 parts                                   
     N-phenylthiocarbamine     10 parts                                   
     starch                    3 parts                                    
     titanium dioxide          8 parts                                    
     H.sub.2 O                 130 parts                                  
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     thickness of application--5.3 g/m 2   
     In place of zinc chloride, copper (II)-chloride may be used in this example. 
     
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 EXAMPLES FOR COLOR-PRODUCING MASS                                        
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(A)     urea                 2 parts                                      
        crystal violet lactone                                            
                             5 parts                                      
        benzoyl-leukomethyl blue                                          
                             2 parts                                      
        titanium dioxide     25 parts                                     
        polyvinyl alcohol    4 parts                                      
        water                140 parts                                    
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     With an application of 2.8 g/m 2 , there is obtained a blue color. 
     
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(B)      urea               4 parts                                       
         3,3-indoylrothphthalide                                          
                            2 parts                                       
         crystal violet lactone                                           
                            6 parts                                       
         calcium carbonate  20 parts                                      
         vinyl acetate      6 parts                                       
         acetone            105 parts                                     
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     With an application of 2.1 g/m 2 , there is obtained a violet script. 
     
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(C)      thiocarbamine      3 parts                                       
         malachite green lactone                                          
                            10 parts                                      
         kaolin             15 parts                                      
         polystyrene        4 parts                                       
         trichloroethylene  80 parts                                      
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     With an application of 2.5 g/m 2 , there is obtained a green script. 
     
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(D)  3-diethylamino-6-methyl-7-anilino-fluoride                           
                                10 parts                                  
     calcium carbonate          30 parts                                  
     synthetic resin on a basis of styrene and                            
     maleic acid ester          6 parts                                   
     ethyl alcohol              90 parts                                  
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     With a coating of 2 g/m 2 , there is obtained a black coloring.