CA2865433C - Natural oil derived gelled ink vehicles - Google Patents

Abstract

Novel natural oil derived ink vehicles are provided by a two step process that does not require the addition of gelants or the irreversible heat bodying or polymerization of the oil. The gelled natural oil may be used as the vehicle/carrier in the ink formulation or alternatively used as a carrier or dispersant for additves in ink formulations. The gelled ink vehicles disclosed have many advantages over ink vehicles disclosed in the prior art.

Description

NATURAL OIL DERIVED GELLED INK VEHICLES
BACKGROUND OF THE INVENTION
The primary component of lithographic printing inks is a gelatinous or gelled vehicle or carrier that must possess sufficient viscosity to disperse finely divided pigments, anti-abrasion additives, and other solid components. Historically, the vehicle or carrier has been based on hydrocarbon based resins, and the control of the rheology of the ink vehicle has historically been challenging. In order to achieve the required gel structure, gelants must be added to the resin.
Typical gelants are the aluminum acylates or alkoxides as described in US
5,427,615 and modified clays as described in US 4,193,806. Other molecular gelants such as polyamide resins and styrene-butadiene block copolymers have been used as gelants in hydrocarbon based oils and solvents. There are several undesirable aspects associated with the use of these gelants.
Organoaluminum based gelants are typically provided in solvents at low concentration of the active aluminum component thus increasing the percentage of VOC's in the formulation. Heat is required for gelation to occur and precise temperature control is required or the gel structure can be destroyed. The modified clays also require heat and sometimes high shear is required to activate or open the clay structure in order for gelation to occur. Polyamide and block copolymer based gelants must be used at high weight percent loadings, typically 20 percent or higher, in order to achieved the desired viscosity. In addition all of these gelants add substantially to the cost of the ink vehicle.
There has been considerable interest in developing vehicles or earners for oil-based printing inks that do not require petroleum or hydrocarbon based components. Decreasing supplies of petroleum, environmental concerns, and interest in biodegradable and renewable resources have prompted the ink manufacturers to initiate efforts to develop inks with vehicles based on biodegradable materials to reduce the industry's dependency on petroleum. 1) ("Vegetable-Oil-Based Printing Ink Formulation and Degradation". Erhan, S.Z, Bagby, M.O.
Industrial Crops and Products. 3 (1995). 237-246. 2) "Vegetable Oil-Based Printing Inks".
Erhan, S.Z, Bagby, M.O. JAOCS, Vol. 69, no. 3 (1992) 251.
The primary means for increasing the viscosity or gelation of natural oils has historically been referred to as "heat-bodying" the oil. In this process, unsaturated natural oils are subjected to high temperatures, typically 300-340 deg C in an inert atmosphere in order to promote chemical crosslinking at the sites of unsaturation in the triglyceride oil.
This process as described in US 5,122,188 and US 6,418,852 typically results in oils with viscosities in the range 1600-1800 centipoise. In order to obtain higher viscosities, a second type of heat-bodying process Is employed in which the high temperature heating is continued until the oil is irreversibly gelled. This intractable gel is then heated at about 340 deg C
with unmodified oil to produce the desired viscosity. It is often necessary to filter insoluble clumps of gelled oil from these blends. In addition, because both of these processes result in irreversible chemical crosslinks between the triglyceride oil chains; it is difficult to maintain obtain precise control of the viscosity. Both of these processes also require rigorous exclusion of oxygen in order to prevent oil degradation and discoloration.
The present invention discloses gelled natural oils useful as ink vehicles and a novel method for their production. The natural oil gelled ink vehicles of the present invention offer several advantages over gelled vehicles disclosed in prior art in that no gelants are required and "heat-bodying" of the oil is unnecessary. The viscosities of the natural oil gelled ink vehicles may also be precisely controlled.
OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide biodegradable natural oil derived gelled vehicle/carrier compositions that can be incorporated into ink and coating formulations.

2 Another object of the present invention is to provide biodegradable natural oil derived gelled vehicle/carrier compositions that are derived from a renewable resource in place of non-renewable petroleum based compositions.
A further object of the present invention is to provide biodegradable natural oil derived gelled vehicle/carrier compositions that do not require the addition of gelants in order to achieve desired viscosities.
An additional object of the present invention is to provide biodegradable natural oil derived gelled vehicle/carrier compositions that do not require high temperature "heat-bodying" of the oil.
A still further object of the present invention is to provide biodegradable natural oil derived gelled compositions useful as vehicles for additives in ink formulations.
MILE juacHmuja Figure 1 shows that the viscosity may be controlled by the amount of neutralization of the maleic anhydride moieties.
Figure 2 shows the precise viscosity control of the vehicle that can be achieved by varying the percentage of the theoretical stoichiometric amount of triethanolamine added.
Figure 3 illustrates clay loadings of up to 75 percent achieved with a soybean oil gel of Example 11 while loadings of only 50 percent were achieved with the standard soy based alkyd resin.
SUMMARY OF THE INVENTION
The instant invention provides a gelled printing vehicle for heatset or other lithographic printing comprising an adduct derived from the reaction product of a natural unsaturated triglyceride oil, or derivative with a substrate suitable for Diels Alder reaction or Ene reaction and wherein said adduct is reacted in a non-aqueous neutralization reaction with a suitable base to form an ionomeric anhydrous gel.

3 The invention also relates to a gelled printing vehicle for heatset or other lithographic printing comprising an adduct derived from the reaction product of an unsaturated triglyceride oil, or derivative with a substrate suitable for Diels Alder reaction or Ene reaction; said adduct being reacted in a non-aqueous neutralization/esterification reaction with an alkanolamine to form an ionomeric anhydrous gel.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention provides gelled vehicles for non-aqueous ink formulations that are derived from natural oils. Thermoreversible gels of unsaturated natural oils of any desired viscosity are conveniently obtained by a simple economical two step process. This process has been described in detail in Applicant's U.S. co-pending application 13/776,542 filed February 25, 2013 and will be summarized here.
In the first step, the unsaturated natural oil, fatty acid or derivative thereof is modified by a process in which the double bonds and/or conjugated double bonds of the triglyceride oil chains are reacted via thermal condensation with an unsaturated substrate which is capable of undergoing an "ene" reaction or an Diels Alder reaction with the sites of unsaturation resulting in the formation of an adduct of the triglyceride oil. The adduct formed is preferentially an anhydride and the substrate reacted in this manner with the triglyceride oil is preferably maleic anhydride. The term "maleation"
been historically applied to the reaction of natural unsaturated oils, fatty acids and their derivatives.
Functionaliztion of triglyceride oils by this method is well known in the art and is described in US
2,033,131, 2,033,132 and 2,063,540. These adducts are generally referred to in the literature as "maleated oils" or maleinized oils". The aqueous neutralization of these natural oil adducts is also well known in the art to produce soaps, emulsifiers and water-based lubricants.
The method described in co-pending application 13/776,542 involves the controlled non-aqueous neutralization of such adducts to provide thermoreversible ionomeric gels. As described in co-pending application 13/776,542 either an alkali or alkaline earth metal base may be employed

4 as the neutralization agent or an alkanolamine may be employed as a neutralization/esterification agent to produce the gels.
This method has proven to be applicable to a wide range of natural unsaturated oils and their derivatives and allows thermoreversible gels of any desired viscosity, from viscous liquids to hard solid gels, to be produced. As described' the method has many advantages over the prior art in that the gels are conveniently and economically produced and do not require the addition of expensive gelants or require the thermal "heat bodying" of the oil. The natural oils that may be used in the method of the present invention include any triglyceride oil that contains significant portions of unsaturated fatty acids. Natural triglyceride oils containing both non-conjugated and conjugated double bonds are suitable. Non-limiting examples of suitable triglyceride oils include soybean oil, linseed oil, safflower oil, sunflower oil, rapeseed oil, castor oil, tall oil, rosin oil and tung oil.

The following examples are intended to illustrate particularly exemplary Natural Oil Gels of the present invention and should not be construed to limit its scope or applicability in any way.
The following general method was used to prepare the Natural Oil Gels listed in Table 1.
In a first step, 2000g of the natural oil and the desired amount of maleic anhydride were charged to a 3 L four-neck round-bottom flask. The contents of the flask were gradually heated to 210 C with agitation under a nitrogen sparge. The reaction mixture was held at this temperature until no free maleic anhydride was detected in the reaction mixture by GC analysis. The reaction mixture was cooled to 50 C and an amount of Sodium Carbonate (0.25eq. per eq. maleic anhydride) was slowly added. The Sodium Carbonate could be added as a solid or as a water slurry.
The reaction mixture was held at 60 C until all of the Sodium Carbonate had reacted and the reaction mixture had cleared.
Excess water was stripped out under vacuum and the gel obtained was discharged. The gels obtained had exemplary properties, being clear and transparent and exhibited no oil bleed.
Table I.
Properties of Gelled Natural Oils IExam le I Percent Maleic Anhdride I Clarit I Oil Bleed I
Viscosit(cP) I
1) Soybean Oil 7.5 Transparent None 1000 2)Soybcan Oil 8 Transparent None 8000 3) Soybean Oil 9 Transparent None 5000 4) Soybean Oil 10 Transparent None 20000 )Soybean Oil 11 Transparent None Soft Gel (Slight Tack) 6) Soybean Oil 12 Transparent None Hard Gel (No tack) 6) Linseed Oil 7.5 Transparent None 5000 7)Linseed Oil 8 Transparent None 12000 8 )Linseed Oil 9 Transparent None 20000 9) Linseed Oil 10 Transparent None 80000 10)Linseed Oil 12 Transparent None Hard Gel (No tack) The viscosity of the gels in Examples 1-10 was controlled by the amount of maleic anhydride grafted on the fatty acid chains of the oil. Alternatively, the viscosity may also be controlled by the amount of neutralization of the maleic anhydride moieties as shown in Figure 1.

The following general method was used to prepare the natural oil gels listed in Table 2.
In a first step, 2000g of the natural oil and the desired amount of maleic anhydride were charged to a 3 L four-neck round-bottom flask. The contents of the flask were gradually heated to 210 C
with agitation under a nitrogen sparge. The reaction mixture was held at this temperature until no free maleic anhydride was detected in the reaction mixture by GC analysis. The reaction mixture was cooled to 50 C and triethanolamine or an alkoxylated triethanolamine (0.67 eq. per 1.0 eq. maleic anhydride) was slowly added. The reaction mixture was held at 80 C for I hour or until no unreacted maleic anhydride was observed in the Infrared Spectrum of the reaction mixture and the gel obtained was discharged.

Table 2.
Properties of Gelled Natural Oils Example Percent Maleic Anhydride Clarity Oil Bleed Viscosity( cP) 11) Soybean Oil 7.5 Transparent None 4500 12) Soybean Oil 8 Transparent None 8700 13) Soybean Oil 9 Transparent None 21000 14) Soybean Oil 10 Transparent None 46000 15) Soybean Oil 11 Transparent None Soft gel (slight Tack) 16) Soybean Oil 12 , Transparent None Hard Gel (No tack) 17) Linseed Oil 7.5 Transparent None 6200 18)Linseed Oil 8 Transparent None 9500 19)Linseed Oil 9 Transparent None 23000 20) Linseed Oil 10 Transparent None Soil Gel (Slight Tack) 21) Linseed Oil 12 Transparent None Hard Gel (No tack) Figure 2 shows the precise viscosity control of the vehicle that can be achieved by varying the percentage of the theoretical stoichiometric amount of triethanolamine added. A soybean oil/maleic anhydride adduct at 10.0 percent maleation was prepared as in examples 11-21. Triethanolamine was added from 20 percent to 70 percent of the theoretical stoichimetric amount required to react with all of the maleic anhydride moieties. The gels were discharged and viscosities were measured at 25 deg C. Above 70 percent theoretical Triethanolamine, hard gels were obtained.

Biodegradable Natural Oil Based Gelled Ink Vehicle Soybean oil gels of different viscosities as prepared in examples 1-10 and examples 11-21 were utilized as a carrier for the preparation of polytetrafluorethylene dispersions. Such dispersions are known in the art to be useful as additives in non-aqueous ink formulations to provide friction reduction and abrasion resistance to the final prints. The dispersions were prepared by mixing micronized PTFE into the gelled soybean oil at 80 C for 1 hour, allowing the mixtures to cool and then discharging. Dispersions were prepared at 25% and 75% PTFE
loading. Control dispersions were made using a standard soy based alkyd resin. The dispersions were then aged at 50 C in order to evaluate dispersion stability. The additives based on the soybean oil gels and the control alkyd were then formulated into a pigmented ink and prints were prepared. The prints were dried and then subjected to abrasion resistance testing. The results are shown in Table 3.
Table 3 Vehicle /Viscosity (cP) Percent PTFE Disnersion Stabilitvc Print Rub Resistance d 24) Soybean Oil Gel (9000 cP) 25 7 6 25) Soybean Oil Gel (9000 cP) 75 6 .. 6 26) Soybean Oil Gel (15000 cP) 25 8 8 27) Soybean Oil Gel (15000 cP) 75 7 .. 9 28) Soybean Oil Gel (20000 eP) 25 10 10 29) Soybean Oil Gel (20000 cP) 75 8 10 30) Soy based Alkyd (9000 cP) 25 4 4 31) Soy based Alkyd (9000 ell 75 4 4 c Dispersion Stability was evaluated by ageing samples at 50 deg C for 72 hours and monitoring the amount of PTFE that had settled. The dispersions were rated on a scale from 1-10. 1 being the worst stability and 10 the best.
d The rub resistance of the prints was rated on a scale from 1-10 with 1 being the worst rub resistance and 10 the best.

Clay Dispersions A soybean oil gel as prepared in Example 11 having a viscosity of 4500 cP was utilized as a carrier or dispersant for the preparation of stable dispersions of bentonite clay in soybean oil which are utilized as fillers in heat set inks. A soy based alkyd resin, commonly used in the industry, was used as a control or comparative example. As shown in Figure 3, clay loadings of up to 75 percent were achieved with a soybean oil gel of Example 11 while loadings of only 50 percent were achieved with the standard soy based alkyd resin.
The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims (4)

What is claimed is:

1. A non-aqueous ink formulation comprising a polytetrafluoroethylene dispersion comprising a gelled printing vehicle for heat-set or other lithographic printing, the vehicle comprising an adduct derived from the reaction product of a natural unsaturated triglyceride oil, or derivative with a substrate suitable for Diets Alder reaction or Ene reaction and wherein said adduct is reacted in a non-aqueous neutralization reaction with a suitable base to form an ionomeric anhydrous gel.

2. The non-aqueous ink formulation of claim 1, wherein the base is an alkanolamine.

3. The non-aqueous ink formulation of claim 1 or 2, wherein the gelled printing vehicle is used as carrier or vehicle for additives in the non-aqueous ink formulation.

4. The non-aqueous ink formulation of claim 1 or 2, wherein the gelled printing vehicle is used as dispersant for additives in the non-aqueous ink formulation.