Abstract:
Flow agent-dispersant composition for ink systems and the like comprising montan wax having from 3 to 10% of lecithin uniformly dispersed therein and a process for forming the same.

Description:
This is a continuation of application Ser. No. 07/475,852 filed Feb. 6, 1990, now abandoned. 
    
    
     This invention relates to improved dispersant and flow agent wax compositions for inclusion in mixtures of finely divided solids materials in readily liquifiable vehicles and particularly to improved dispersant-flow wax compositions for inks such as carbon paper inks and the like and to a process for making the same. 
     BACKGROUND OF THE INVENTION 
     Certain vegetable waxes, such as carnauba or ouricury wax or certain mineral waxes, such as montan wax, both basic and modified, have long been conventionally utilized to impart highly beneficial hardness and oil retention properties to ink systems, such as carbon paper inks, as well as to enhance the dispersion of solid particulate matter in diverse products incorporating readily liquifiable carrier vehicles. The continually increasing price of such vegetable and mineral wax materials, coupled with the uncertainties attendant their common sources of supply, has forced manufacturers to utilize continually decreasing amounts thereof in carbon paper inks and similar materials for selective functioning as &#34;flow waxes&#34; to obtain satisfactory dispersion properties therein, with other and less expensive materials being substituted therefor to impart the desired hardness and oil retention properties to the product. Even in such reduced amounts, however, the material costs for such vegetable and mineral waxes have risen to such an extent as to pose serious economic problems for the manufacturers of carbon paper inks and similar products. 
     The problem is one of long standing. Prior efforts in the art have been directed to the provision of domestically available synthetic waxes that are possessed of at least some desirable flow agent properties. While such synthetic waxes have provided some advantageous flow agent properties, they have not, as yet, provided the highly beneficial hardness and oil retention properties that are normally required in inks and like products that include a normally solid but readily liquifiable carrier vehicle. Exemplary of the foregoing are the modified synthetic waxes disclosed in U.S. Pat. Nos. 2,890,124, 2,890,125 and 3,163,548. These synthetic waxes, unfortunately, have likewise been characterized by progressively increasing costs for the resultant product and such has operated to accentuate rather than to alleviate the basic problem. 
     A more recent synthetic wax base product is disclosed in U.S. Pat. No. 3,941,608. Here again however, continually increasing raw material and processing costs have resulted in progressively increasing costs for the resultant product. 
     Apart from the increasing cost factor as above noted, the resultant economically dictated utilization of increasing amounts of paraffin wax and other substitutes for the above named vegetable and mineral waxes has increased the likelihood of detrimental gelling of the ink systems and other products being formulated therefrom. 
     As noted above, montan waxes, of both the basic and modified type, have been long recognized as having the ability to impart beneficial hardness and oil retention properties to, as well as the ability to enhance the dispersion of solid particulate matter in, diverse products utilizing readily liquifiable carrier vehicles. Basic montan wax is a mineral wax, solvent extracted from lignite, and is made up of a complex mixture of high molecular esters of long-chain aliphatic acids and wax alcohols. Both basic montan wax and chemically treated or modified montan waxes are hard waxes of microcrystalline structure and are commercially available products. 
     SUMMARY OF THE INVENTION 
     This invention may be briefly described as a chemically modified montan wax that can be advantageously employed as a dispersant-flow agent wax composition for ink systems and particularly for carbon paper inks and to methods of forming the same. In its broader aspects, the chemically modified montan wax product is obtained by the reaction of a montan wax with lecithin. In a narrower aspect, the invention includes the provision of a lecithin modified montan wax containing from three to about ten percent of lecithin. 
     Among the advantages of the subject invention is the provision of an effective dispersant for finely divided solids in liquifiable carrier vehicles, such as ink systems and particularly in carbon paper inks, that has flow imparting properties superior to those of natural vegetable waxes such as carnauba and ouricury, and available montan waxes, and which, in addition to markedly reducing the hazards of detrimental gelling, can be made available at a fraction of the cost of any of the presently available dispersant materials conventionally employed as flow agents in such environments. A further advantage is the provision of a simple and economic method of forming such improved dispersant-flow agents characterized by significantly low operating temperatures and markedly reduced raw material costs as compared to those attendant presently available modified natural and synthetic wax dispersants of the type identified above. A still further advantage of this invention is the provision of an improved wax like dispersant and flow agent to beneficially enhance the properties of liquifiable carrier vehicles for diverse products and permit the use of fillers and lower cost wax materials therein. 
     The primary object of this invention is the provision of a lecithin modified montan wax dispersant-flow agent for ink systems and particularly for carbon paper inks. 
     A further object of this invention is the provision of an economic method of producing an improved lecithin modified dispersant-flow wax for carbon paper inks. 
     Other objects and advantages of the subject invention will become apparent from the following portions of this specification and appended claims which, in accord with the mandate of the patent statutes, discloses the principles of the invention as embodied in presently preferred chemically modified montan wax dispersant-flow agent products and a process for forming the same. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As previously pointed out, montan wax is a natural mineral wax obtained by solvent extraction from lignite and is the base constituent of the improved product. Montan wax is a naturally occurring fossil hard wax made up of a variety of waxes and is a complex mixture of high molecular esters of long chain aliphatic acids and alcohols in association with small amounts of color intensive asphaltic resins. Montan wax is available in basic solvent extracted form and as modified by various chemical aftertreatments. A primary producer of montan waxes is the VEB Braunkohlenwerk &#34;Gustav Sobottka&#34; DDR-4256 Roblingen am See, GDR which produces and sells both basic montan wax and modified or chemically aftertreated montan waxes under the trademark ROMONTA. Another producer of montan waxes is the American Lignite Products Co. of Ione, California which produces and sells both basic and modified or chemically aftertreated montan waxes under the trademark ALPCO. Preferred montan waxes of both the basic or modified types for use in the practice of this invention include, by way of example, the following: 
     
         ______________________________________      Saponification        Solidification      Value       Acid Value                            Point      (ASTM       (ASTM     (ASTMMontan Wax DF1389)     D1386)    F766)______________________________________ROMONTA    85-100      27-33     167-185° F.(Standard)ROMONTA 76 85-95       14-20     172-181° F.ROMONTA C  90-105      23-28     172-182° F.ROMONTA 6715      92-102      23-28     174-183° F.ALPCO 16   85-115      40-60     178-185° F.(Standard)ALPCO 1600 85-115      22-30     178-186° F.ALPCO 1650             23-28     179-188° F.______________________________________ 
    
     The modifier reactant is lecithin. Lecithin is a phosphoglyceride or phosphotide or, more usually, a mixture of the diglycerides of stearic, palmitic and oleic acids linked to the choline ester of phosphoric acid. One of the most common and abundant phosphoglycerides is choline phosphoglyceride which, when pure, is a waxy white solid. Lecithin is commercially produced from soya bean oil and usually consists of a mixture of phosphatides, largely phosphatidyl-choline; phosphatidyl-ethanolamine and phosphatidyl-serine. 
     The dispersant-flow agent wax embodying the subject invention is generally formed by heating the montan wax base constituent to a temperature between 220° and 350° F., preferably about 235° F., in a mixing vessel with good agitation to render it highly fluid. Lecithin is slowly added, with continued agitation, in an amount in the range of from a minimum of about 3 to a maximum of about 10% by weight. If desired, the lecithin can be incrementally added to the molten montan wax. After lecithin addition has been completed the reaction, under continued agitation, is continued for at least one hour. After the reaction has been completed, the improved dispersant-flow agent in the nature of a lecithin modified montan wax may be flaked, prilled or otherwise cooled and mechanically processed to desired form. 
     By way of further example, two formulations of carbon paper ink employing varying amounts of the improved dispersant-flow agent were formulated and their comparative viscosities measured through use of a No. 2 Zahn cup having a delivery aperture of predetermined size therein. The inks were all heated to 200° F. and measured amounts thereof were introduced into the No. 2 Zahn cup. The time required to drain the cup, measured in seconds, is generally indicative of the relative viscosity of the particular carbon paper ink being tested. The lower the drain time period, the lower is the viscosity and vice versa. The two carbon paper ink formulations subjected to test and differing in the main wax vehicle were constituted as follows: 
     
         ______________________________________Formula A        Formula B______________________________________Montan Wax Constituent          6%    Montan Wax Constituent                                 6%Paraffin type slack wax         42%    Microcrystalline type                                42%Petrolatum    15%    slack wax100 second paraffin oil         12%    Petrolatum      15%Carbon black  20%    100 second paraffin oil                                12%Clay           5%    Carbon black    20%                Clay             5%______________________________________ 
    
     The following viscosity tabulation clearly indicates the beneficial characteristics of lecithin modified montan waxes: 
     
         ______________________________________Specific MontanWax Constituent  Formula A   Formula B______________________________________Alpco 16 (standard)            no exit flow                        no exit flowAlpco 16 + 7% lecithin            43 seconds  60 seconds +Alpco 1600       no exit flow                        no exit flowAlpco 1600 + 7% lecithin            38 seconds  55 secondsAlpco 1650       29 seconds  45 secondsAlpco 1650 + 7% lecithin            23 seconds  32 secondsRomonta (Standard)            no exit flow                        no exit flowRomonta + 7% lecithin            43 seconds  60 seconds +Romonta 6715     38 seconds  60 seconds +Romonta 6715 + 7% lecithin            30 seconds  55 secondsRomonta 76       33 seconds  47 secondsRomonta 76 + 7% lecithin            20 seconds  22 secondsRomonta C        27 seconds  45 secondsRomonta C + 7% lecithin            18 seconds  21 seconds______________________________________ 
    
     As will be apparent from the foregoing, the utilization of the lecithin modified montan wax has, in every instance, resulted in a marked decrease in the viscosity of the carbon paper ink at 200° F. 
     Beneficial properties derived from the use of the lecithin modified wax montan waxes have generally been obtained where the percentage of lecithin has varied between about three up to about ten percent by weight. A preferred percentage range for lecithin content is about 5 to 8% and optimum results appear to be obtained where the lecithin percentage is about seven percent. Lecithin addition of as little as 3 percent clearly improves the product, while lecithin additions of over ten percent do not appear to further markedly improve the viscosity and also may result in adverse effects on the hardness and oil retention characteristics of the finished product. 
     Generally indicative of the foregoing are the following viscosity values with variations in lecithin content in the Formula A composition utilizing Romonta C wax as the basic montan wax constituent: 
     
         ______________________________________Romonta C                27 sec.Romonta C + 3% lecithin  29Romonta C + 5% lecithin  25Romonta C + 7% lecithin  18Romonta C + 10% lecithin 18______________________________________ 
    
     Further examples of viscosity reduction through lecithin addition to montan waxes, again employing the No. 2 Zahn cup and 200° F. wax, have been attained as follows: 
     
         ______________________________________      LecithinWax          0%       3%        7%   10%______________________________________Alpco 1650   45       40        32   31Romonta 6715 no flow  60        55   54Romonta 76   47       38        22   23______________________________________ 
    
     In general, it appears that the amount of lecithin to be used is dependent, at least in part, upon the nature of the ink vehicle and the amount of pigment being utilized. Ink formulations with reduced pigment content appear to require less lecithin with permitted usage of a harder wax base. If larger amounts of pigment than that specified in Formula B are employed in the ink formulation, increased percentage of lecithin and/or increased percentage of montan wax constituent would appear to be required. 
     A further carbon black ink identified as Formula C, and comprising 
     
         ______________________________________Montan Wax Constituent               5%Carnauba Wax        2%Slack Wax          56%70 Sec. Paraffin Oil              12%Carbon Black       20%Clay                5%______________________________________ 
    
     was made up in five samples that included the montan wax constituent as follows: 
     
         ______________________________________Sample #1       Romonta CSample #2       Alpco 1650Sample #3       Romonta C + 7% lecithinSample #4       Romonta C + 7% lecithinSample #5       Romonta C + 7% lecithin______________________________________ 
    
     These samples were subjected to the above described viscosity testing under various aging conditions without agitation with the following results: 
     
         ______________________________________Aging    #1       #2       #3      #4  #5______________________________________Initial  40       44       23      22  20 1 Hour  42       52       30      33  30 2 Hours 42       52       32      34  37 4 Hours 43       over 60  29      43  3924 Hours 45       over 60  38      45  40______________________________________ 
    
     It appears from the above that the lecithin modified samples have generally improved aging qualities or stability, which facilitates the usage thereof in the commercial fabrication of diverse products. 
     It has been found that reaction time and temperature may be varied somewhat for different montan wax base constituents. By way of specific example, 465 grams of Romonta Type C wax having the typical specification: 
     
         ______________________________________melting point °F.              172-181acid value         22-28saponification value               92-110specific gravity @ 77° F.              1.00______________________________________ 
    
     was heated in an agitated vessel to about 235° F. After the montan wax reached 235° F., 35 grams of Archer Daniels Midland lecithin was added and the reaction was allowed to proceed for at least 30 minutes under continuing agitation. The molten material was then cooled into the desired form. The resultant lecithin modified wax had the following properties: 
     
         ______________________________________melting point °F.              175-185acid value          8-14saponification value              78-86specific gravity @ 77° F.              1.08______________________________________ 
    
     As further illustrative of reaction temperature criticality, a fourth carbon black ink formulation constituted of 
     
         ______________________________________Formula D______________________________________Montan Wax Constituent               5%Carnauba Wax        2%Slack Wax #3       41%Petrolatum         15%120 sec paraffin oil              12%Carbon black       20%Clay                5%______________________________________ 
    
     was made up in five samples with the montan wax constituent as follows: 
     
         ______________________________________Sample 1  Alpco 1650Sample 2  Romonta 76 + 7% lecithin reacted at 300° F.Sample 3  Romonta 76 + 7% lecithin reacted at 275° F.Sample 4  Romonta 76 + 7% lecithin reacted at 235° F.Sample 5  Romonta C + 7% lecithin reacted at 235° F.______________________________________ 
    
     These samples were subjected to the above described viscosity test under various aging conditions without agitation with the following results: 
     
         ______________________________________Aging    #1         #2    #3       #4  #5______________________________________Initial             26    27       28  20 1 Hour  48         27    33       35  24 2 Hours 50         29    35       38  26 4 Hours 52         29    36       42  2724 Hours 55         32    38       47  29______________________________________ 
    
     The herein described lecithin modified montan wax products maintain or improve the properties of montan wax with respect to hardness and oil retention and greatly enhances the flow and dispersion properties thereof. While the contemplated principle use of this product will be in the carbon paper industry, the lecithin modified montan wax product may well have significant application in other normally solid but liquifiable carrier vehicle products which require pigment dispersion. Some possible applications would be in printing inks, carbon ribbon inks, plastics, paint and polishes.