Abstract:
A pressure-sensitive copying material which employs a color-producing substance and a color substance-accepting material is disclosed. The color substance-accepting material contains, as reaction components, a chloride of a metal having an atomic weight of from 50-66, together with a urea or its derivatives and a binding agent. The color-producing substance includes a dyestuff which is combined with the binding agent and reacts with the color substance-accepting material during color formation.

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______________________________________Reaction IntensityMass Acetone            H.sub.2 O______________________________________1    almost no reaction very weak reaction2    reaction color too light                   good reaction3    no reaction        no reaction4    reaction as in 2   reaction as in 25    reaction as in 1   reaction as in 16    substantially stronger                   very strong reaction,reaction as in 1 to 5                   better than in 1 to 57    reaction more intensive                   reaction more intensivethan in 6          than in 68    no improvement in  no improvement inreaction over 7    reaction over 7______________________________________ 
    
     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. 
     
         ______________________________________EXAMPLES FOR COLOR-SUBSTANCE ACCEPTOR-MASSES:______________________________________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.22.  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.23.  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.24.  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.25.  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.26.  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.27.  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.28.  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.29.  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.210. 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.211. 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.212. 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.213. 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.214. 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______________________________________ 
    
     In place of iron (III)-chloride, there may be employed chromium (III)-chloride, vanadium (III)-chloride or manganese (III)-chloride. 
     
         ______________________________________15.  zinc chloride             16 partsdiphenyl thiocarbamine    6 partspolyvinyl alcohol         1.5 partscalcium stearate          5 partsH.sub.2 O                 90 partsthickness of application - 4.3 g/m.sup.216.  nickel (II)- or cobalt (II)-chloride                          18 partsdiphenyl thiocarbamine    6 partspolyvinyl alcohol         1.5 partscalcium stearate          5 partsH.sub.2 O                 90 partsthickness of application - 4.4 g/m.sup.217.  zinc chloride             15 partsurea                      10 partspolyvinyl butyral         3 partsmodified pentaerythrite ester                          2 partscalcium carbonate         10 partszinc stearate             4 partsethyl alcohol             120 partsthickness of application - 0.9 g/m.sup.218.  zinc chloride             20 partsN-phenylthiocarbamine     10 partsstarch                    3 partstitanium dioxide          8 partsH.sub.2 O                 130 parts______________________________________ 
    
     thickness of application--5.3 g/m 2   
     In place of zinc chloride, copper (II)-chloride may be used in this example. 
     
         ______________________________________ EXAMPLES FOR COLOR-PRODUCING MASS______________________________________(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______________________________________ 
    
     With an application of 2.8 g/m 2 , there is obtained a blue color. 
     
         ______________________________________(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______________________________________ 
    
     With an application of 2.1 g/m 2 , there is obtained a violet script. 
     
         ______________________________________(C)      thiocarbamine      3 parts    malachite green lactone                       10 parts    kaolin             15 parts    polystyrene        4 parts    trichloroethylene  80 parts______________________________________ 
    
     With an application of 2.5 g/m 2 , there is obtained a green script. 
     
         ______________________________________(D)  3-diethylamino-6-methyl-7-anilino-fluoride                           10 partscalcium carbonate          30 partssynthetic resin on a basis of styrene andmaleic acid ester          6 partsethyl alcohol              90 parts______________________________________ 
    
     With a coating of 2 g/m 2 , there is obtained a black coloring.