Viscosity-stable high solids rosin-phenolic resin solutions

Abstract: The invention relates to improved solution phenolics and the process for preparing them. In particular, the invention relates to viscosity-stable high solids solutions of esters of rosin-phenol condensates having properties which make them useful in formulating vehicles for gravure printing inks.

Description: Field of Invention The invention relates to novel solution phenolics and the process for preparing them. In particular, the invention relates to viscosity-stable high solids solutions of esters of rosin-phenol condensates having properties which make them useful in formulating vehicles for gravure printing inks. Background of the Invention Hydrocarbon solutions of resin esters of rosin-phenol condensates are known in the ink industry as solution phenolics. Solution phenolics are commonly employed by ink manufacturers in formulating vehicles for gravure printing inks. However, a major problem exists with the use of solution phenolics in that they tend to increase in viscosity over time. The rate of this viscosity growth is concentration-dependent, thereby worsening as the level of resin solids contained in a solution increases (see Table I below). Compounding this problem is the fact that viscosity growth in solution phenolics is also accompanied by undesirable variations in dilution values. As these time-dependent differences in the physical properties of solution phenolics cannot be predicted easily, the resulting variabilities create major problems for ink manufacturers. These twin problems of viscosity growth and dilution value variation are graphically shown by the data listed in Table I below. Here, varying amounts of JONREZ® RP-346 (a rosin-phenolic resin manufactured by Westvaco, Inc.) were dissolved in toluene to produce solutions having differing resin solid levels. These solution phenolics were sealed in jars to prevent toluene evaporation and held at ambient temperatures (about 25°C) for 2 weeks. Viscosity Growth as a Function of Time and Solids For Untreated Solution Phenolics Percent Solids Physical Property Day 1 Day 7 Day 14 Percent Change 45 Brookfield Viscosity (mPas) 16,800 41,000 88,530 427 Dilution (mL) 297 297 314 6 37 Brookfield Viscosity (mPas) 1100 1950 3050 177 Dilution 198 213 198 0 30 Brookfield Viscosity (mPas) 190 205 336 77 Dilution 130 144 140 8 Table I shows that the rate of viscosity growth was proportional to the percent solids of the aged solution: the higher the solids level, the greater the increase in viscosity over time. For example, at 45% nominal solids a toluene solution of JONREZ RP-346 increased 427% (from 16,800 mPas to 88,530 mPas) in 14 days. At 37.5% nominal solids, a toluene solution of JONREZ RP-346 increased 177% in viscosity (from 1100 mPas to 3050 mPas) in 14 days. At 30% solids, a toluene solution of JONREZ RP-346 only increased 77% in viscosity in 14 days. As heretofore there has been no solution to this problem, the ink industry is currently limited to retarding viscosity growth by utilizing rosin-phenolic resin solutions containing low solids concentrations (i.e., below 25% solids). The ability to create rosin-phenolic resin solutions which are viscosity stable at high solids levels would be greatly advantageous to the industry, especially in the areas of solution formulation, transport, and storage. Therefore, it is the object of this invention to produce viscosity-stable high solids rosin-phenolic resin solutions for use in the formulation of vehicles for gravure printing inks. Summary of the Invention This objective is achieved by the addition of a polyalkanolamine or a polyether alcohol to the hydrocarbon solution of esters of rosin-phenol condensates. The resulting solutions are both viscosity stable and dilution stable, even at high solid levels (i.e., solid levels of 25% or more). As mentioned, the invention is directed to novel viscosity-stable high solids solution phenolics (i.e., solutions of esters of rosin-phenol condensates) and the process for preparing the same. In addition, the invention is also directed to gravure printing ink formulations containing such solution phenolics. According to the present invention there is provided a high solids solution phenolic composition comprising a mixture of: (a) from 25.0 to 75.0% by weight, preferably from 35.0 to 55.0% by weight, of resin esters of rosin-phenol condensates, and (b) from 25.0 to 75.0% by weight, preferably from 45.0 to 65.0% by weight, of a solvent; wherein from 0.2 - 4.0% by weight of said resin esters of a member selected from polyalkanolamines, polyether alcohols, or combinations thereof, is added to said mixture; wherein said polyalkanolamines contain: (1) from 1 to 5 amine groups, (2) from 2 to 7 hydroxyl groups, and (3) where each hydroxyl oxygen atom is separated from an amine nitrogen by 2 carbon atoms; and wherein said polyether alcohols are represented by the chemical structures: where R 1 is hydrogen or C 1 - C 18 alkyl; R 2 is hydrogen, CH 3 , or - CH 2 CH 3 ; R 3 is hydrogen or C 1 - C 4 alkyl; and x is 2 to 15. The viscosity-stable solution phenolics are prepared by adding a member selected from polyalkanolamines, polyether alcohols, or combinations thereof to high solids hydrocarbon solutions of esters of rosin-phenol condensates. The production of esters of rosin-phenol condensates is well known in the ink industry, with a variety of esters being commercially available. A commonly used method for producing these esters is taught in Example 6 of U.S. Patent No. 4,643,848 by Thomas et al. Rosins which are suitable for use in producing these esters may be derived from tall oil rosin, wood rosin, or gum rosin. Solvents which are suitable for producing solutions of these esters of rosin-phenol condensates include aliphatic hydrocarbons, aromatic hydrocarbons, and combinations thereof. Polyalkanolamines which are suitable for use in the invention include compounds containing: a) from 1 to 5 amine groups and b) from 2 to 7 hydroxyl groups where c) each hydroxyl oxygen atom is separated from an amine nitrogen by 2 carbon atoms. These compounds can be generally represented by the chemical structure: where R 1 is hydrogen, C 1 - C 18 alkyl, or - R 2 - OH; each R 2 is independently - CH 2 CH 2 -, R 3 is C 2 - C 6 alkylene or cycloalkylene; and x is 0 to 3. Specific suitable polyalkanolamines include, but are not limited to, the following: triethanolamine, N-ethyldiethanolamine, N,N,N',N'-tetrakis(hydroxypropyl)ethylenediamine, N-methyldiethanolamine, N-butyldiethanolamine, triisopropanolamine, N,N,N',N'-tetrakis(hydroxyethyl)-1,4-cyclohexanediamine, N,N,N',N',N''-pentakis(hydroxypropyl)diethylenetriamine, N,N,N',N'-tetrakis(hydroxyethyl)hexamethylenediamine, and combinations thereof. Polyether alcohols which are suitable for use in the invention include compounds which can be generally represented by the chemical structure: where R 1 is hydrogen or C 1 - C 18 alkyl; R 2 is hydrogen, CH 3 , or - CH 2 CH 3 ; R 3 is hydrogen or C 1 - C 4 alkyl; and x is 2 to 15. Specific suitable polyether alcohols include, but are not limited to, the following: diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol, dipropylene glycol monoethyl ether, diethylene glycol monobutyl ether, tripropylene glycol, tetraethylene glycol, poly(ethylene glycol) 200, poly(ethylene glycol) 400, and combinations thereof. The invention is practiced via the addition of from 0.2 - 4.0% (by weight of resin solids) of polyalkanolamine and/or polyether alcohol to high solids hydrocarbon solutions of esters of rosin-phenol condensates. The preferred addition range of the polyalkanolamine and/or polyether alcohol is from 0.5 -2.0% The addition may occur during formulation of the high solids solution or after the solution has been produced. The high solids level of the hydrocarbon solutions of esters of rosin-phenol condensates ranges from 25.0 - 75.0% by weight, with the preferred range being about 35.0 - 55.0% by weight. As appreciated in the art, the exact components and properties of components desired for any given ink application can vary, and, therefore, routine experimentation may be required to determine the optimal components and proportions of components for a given application and desired properties. The following examples are provided to further illustrate the present invention and are not to be construed as limiting the invention in any manner. Example 1 A series of solution phenolics were produced by dissolving 45% by weight of different molecular weight production lots of JONREZ® RP-346 (a rosin-phenolic resin manufactured by Westvaco, Inc.) in 55% by weight of toluene to produce 45% solids solutions. Half of the resulting solutions were left untreated to serve as controls. The other half of the solutions were treated with varying amounts of triethanolamine (TEA). The results are listed in Table II below. Table II shows that triethanolamine suppressed viscosity growth in four different molecular weights of JONREZ RP-346. The maximum viscosity increase was 37% for Lot #2, which was treated with the smallest amount of TEA (0.9 weight percent TEA based on resin solids). Moreover, Table II shows that 45% solids solutions of the four different lots dropped dramatically in viscosity upon treatment with triethanolamine. The four, untreated solutions of JONREZ RP-346 in toluene exhibited viscosities between 6300 mPas and 16,800 mPas. Upon treatment with 0.9% to 1.6% triethanolamine (by weight of resin), the viscosities of these same solutions dropped to between 1200 mPas and 1750 mPas. This substantial decrease in viscosity also was observed in the physical appearance of the stirred solutions. The four, untreated, 45% solids solutions exhibited Weisenberg effects, tending to climb the stirrer shaft during sample preparation at 80°C. However, upon addition of the triethanolamine, a deep vortex immediately developed in each of these solutions, attesting to the significant viscosity-lowering effect of TEA. Example 2 A series of solution phenolics were produced by dissolving 50% (or 55%) by weight of different molecular weight production lots of JONREZ® RP-346 in 50% (or 45%) by weight of toluene to produce 50% (or 55%) solids solutions. To these solution phenolics were added varying amounts of triethanolamine (TEA). The results are listed in Table III below. Triethanolamine Treatment Stabilizes Viscosity and Dilution In 50% and 55% Solids Solutions RP-346 Physical Property Day 1 Day 7 Day 14 Lot #5 50% Solids 1.7% TEA Brook. Viscosity (mPas) 3030 4006 3230 Dilution 240 250 - Lot #6 50% Solids 1.6% TEA Brook. Viscosity (mPas) 3550 4580 4420 Dilution 260 264 251 Lot #7 55% Solids 1.7% TEA Brook. Viscosity (mPas) 17,250 15,270 14,800 Dilution 297 284 299 Triethanolamine also stabilized the viscosity of solutions prepared at solids higher than 45%. Table III shows that addition of around 1.7 weight percent triethanolamine stabilized the viscosity and dilution properties of RP-346 solutions prepared at 50% and 55% solids. Table III shows no control data for the viscosity of untreated solutions of RP-346 at 50% and 55% solids because the solutions were virtually gelled in the reaction vessel at 80°C prior to triethanolamine addition. It was evident, from this gel formation at 80°C, that at 25°C, the Brookfield viscosities of these untreated 50-55% solids solutions would have been immeasurable. Example 3 A solution phenolic was produced by dissolving 45% by weight of JONREZ® RP-346 in 55% by weight of toluene to produce a 45% solids solution. A portion of the solution phenolic was left untreated as a control group. The remainder of the solution phenolic was treated via the addition of varying amounts of different polyalkanolamines. The results are listed in Table IV below. Number of 1,2-Relationships Between Hydroxyl and Amine Groups Correlates with Viscosity Stability Effectiveness Number of 1,2-Relationships Additive and Treatment Level Physical Property Day 1 Day 7 Day 14 0 Control (None) Brook. Viscosity (mPas) 9430 36,600 89,930 Dilution 262 388 291 3 Triethanolamine 1.3 Brook. Viscosity (mPas) 1750 1540 1570 Dilution 219 230 219 2 N-Ethyldiethanolamine 1.8 Brook. Viscosity (mPas) 1540 1630 1711 Dilution 215 223 223 1 N,N-Diethylethanolamine 1.97 Brook. Viscosity (mPas) 4516 11,660 13,050 Dilution 251 262 262 0 Triethylamine 1.7 Brook. Viscosity (mPas) 9000 - 136,750 Dilution 275 - 310 4 THPD 2.0 Brook. Viscosity (mPas) 1060 1260 1115 Dilution 205 228 - Table IV shows the viscosity-stability effects of these additives. The data indicates that at least two hydroxyalkyl groups were required for viscosity stability. Note that triethylamine, which lacked hydroxyl groups, did not suppress viscosity growth. Similarly, a solution treated with N,N-diethylethanolamine, which contained a single 1,2-relationship between its hydroxyl and amine groups, was not viscosity-stable. In contrast, N-ethyldiethanolamine contained two hydroxyethyl groups, and this additive suppressed viscosity growth to almost the same extent as triethanolamine. The data in Table IV strongly suggests that the number of 1,2-relationships between hydroxyl and amine groups correlated with the extent of viscosity reduction. To confirm this the effect of adding 2.0 weight percent N,N,N'N'-tetrakis(2-hydroxypropyl)-ethylenediamine (THPD) was examined. This compound contained four 1,2-relationships between its hydroxyl and amine groups. The viscosity-lowering effect of this additive appeared to be greater than any other compound in this series of triethanolamine analogues. The initial solution viscosity fell from 9430 mPas in the untreated solution to 1060 mPas in the THPD-treated one. However, after aging 14 days the THPD-treated solutions exhibited a white precipitate. Example 4 A series of solution phenolics were produced by dissolving 45% by weight of different molecular weight production lots of JONREZ® RP-346 in 55% by weight of toluene to produce 45% solids solutions. A portion of one solution phenolic was left untreated as a control group. The remainder of the solution phenolics were treated via the addition of varying amounts of different polyether alcohols. The results are listed in Table V below. Polyether Alcohol Treatment Stabilizes Viscosity and Dilution In 45% Solids Solutions RP-346 Additive and Treatment Level Physical Property Day 1 Day 7 Day 14 Lot #8 Control (None) Brook. Viscosity (mPas) 6800 34,500 55,750 Dilution 262 271 323 Lot #8 Tetraethyle ne-Glycol 2.1 Brook. Viscosity (mPas) 1740 2600 3550 Dilution 235 245 253 Lot #9 Diethylene-Glycol 1.3 Brook. Viscosity (mPas) 2280 2480 2970 Dilution 235 249 241 Lot #10 Diethylene-Glycol 0.9 Brook. Viscosity (mPas) 2250 3370 4860 Dilution 233 247 266 As evidenced by the results shown in Table V, the addition of polyether alcohols result in the stabilization of viscosity and dilution values in solution phenolics. Example 5 A series of solution phenolics were produced by dissolving 45% by weight of different molecular weight production lots of JONREZ® RP-346 in 55% by weight of toluene to produce four 45% solids solutions. The viscosities and molecular weights of the production lots are listed in Table VI below. Viscosities and Molecular Weights of Four Lots of RP-346 Lot Brookfield Viscosity at 25°C and 45% Solids in Toluene (mPas) Resin Molecular Weight Characteristics Mw Mw/Mn Mz/1000 Mz+1/1000 #11 2200 116,400 87 917 1485 #12 2420 131,400 94 951 1509 #13 2200 118,800 87 973 1828 #14 2350 83,100 61 621 1031 A portion of each solution phenolic was left untreated as a control group. The remainder of the solution phenolics were treated via the addition of either 1.0% or 1.5% of TEA. One half of the treated solution phenolics were sealed in jars and stored at ambient temperatures for 2 weeks. The results are listed in Table VII below. Variation Over Fourteen Days in the Viscosities and Dilutions of Triethanolamine-Treated RP-346 Solutions Lot Weight Percent Triethanol-Amine 25°C Brookfield Viscosity (mPas) Dilution (mL) day 1 day 14 day 1 day 14 #11 0 2250 4600 190 190 1.0 1060 1440 170 150 1.5 970 1160 150 150 #12 0 2220 5120 190 210 1.0 1090 1400 160 170 1.5 1000 1230 160 160 #13 0 2240 4500 180 200 1.0 1090 1400 170 170 1.5 1000 1220 160 160 #14 0 1710 1800 170 170 1.0 820 1080 160 150 1.5 570 980 140 140 The remaining half of the treated and untreated solution phenolics were utilized as let-down vehicles in the preparation of gravure inks. The gravure ink formulation consisted of: 1) 32% by weight of a red pigment formulation containing a 24% base of lithol rubine, 2) 50% by weight of the respective let-down solution phenolic, and 3) 18% by weight of virgin toluene. The ink formulations were agitated via a Red Devil paint shaker for 30 minutes, after which time the inks were diluted to a value of 18 seconds as measured by a Shell #2 cup at 25°C. The gravure inks were subsequently sealed in jars and stored at ambient temperatures for 2 weeks. The results are listed in Table VIII below. Fourteen-Day Viscosity and Dilution Changes in Gravure Inks Lot Wt % Triethanolamine 25°C Brookfield Viscosity (mPas) Dilution (s) 60° Ink Gloss day 1 day 14 day 1 day 14 day 1 day 14 #11 0 2940 8250 19.6 22.4 51.0 67.6 1.0 1340 1500 17.6 18.5 50.5 66.1 1.5 1040 1240 19.4 18.0 51.4 63.6 #12 0 2900 8100 19.6 23.7 52.8 66.7 1.0 1300 1540 17.8 19.2 54.65 67.9 1.5 1140 1440 17.8 18.6 54.0 66.5 #13 0 2540 5400 19.7 22.7 51.5 65.3 1.0 1240 1560 18.1 18.9 50.1 66.1 1.5 1100 1280 17.8 17.9 49.7 63.2 #14 0 2060 3350 18.4 19.5 49.9 67.9 1.0 1020 1200 16.8 17.5 48.8 65.0 1.5 920 1060 16.3 16.4 47.9 64.9 Table VIII shows the changes in viscosity and dilution of the gravure inks derived from the triethanolamine-treated, let-down vehicles. Untreated inks increased in viscosity roughly 60 to 180% over 14 days. Inks made from let-down vehicles treated with 1.0% triethanolamine increased in viscosity from 12 to 26% over 14 days. Although increasing the triethanolamine level in the let-down vehicle to 1.5% reduced the viscosity of the vehicle and the resulting ink, the viscosity growth characteristics at the 1.0 and 1.5% levels were comparable. The dilution measurements in Table VIII were made by treating all of the samples with 120 mL of toluene and then recording the time required for the diluted sample to pass through a #2 Shell cup. All of the untreated samples gave higher seconds readings, indicating that they were more dilutable than the treated samples. Drying rate differences between treated and untreated inks were estimated in a simulated drying rate test. Samples of treated and untreated inks were drawn down on a grind gauge, and then a piece of paper stock was impressed onto the drawdowns. Slower drying inks transfer longer drawdowns to the paper. The results are listed in Table IX below. Lengths (cm) of Drawdowns in Simulated Drying Rate Experiments Lot Wt % Triethanolamine in Let-Down Vehicle 0.0 1.0 1.5 #11 12.1 12.8 - 13.2 - 13.6 #12 9.5 10.3 - 9.4 - 10.4 #13 12.0 12.5 0 11.0 - 12.1 #14 10.0 11.8 - 10.0 - 11.4 Table IX shows that, in all cases, the TEA-treated inks gave longer drawdowns than their untreated counterparts, indicating that their drying rates were lower. It is important to note, however, that many of the TEA-treated inks gave drawdowns with lengths within the range exhibited by the untreated inks. For example, the drawdowns of untreated inks ranged in length from 9.4 cm to 13.2 cm. The drawdowns of inks made from let-down vehicles treated with 1.0 and 1.5% TEA ranged in length from 10.3 cm to 13.6 cm. In other words, all but one of the treated ink samples (Lot #11 with 1.5% TEA) gave drawdowns with lengths (and, hence, drying rates) within the range exhibited by the four lots of untreated inks. Although the drying rates of gravure inks formulated with TEA were somewhat increased, the rates were still comparable to those of the control inks. TEA treatment did not adversely affect ink film gloss, film density, or bronzing. Example 6 Esters of rosin-phenol condensates suitable for use in the present invention may be produced via the following procedure. To a suitable reaction vessel equipped with an overhead stirrer, condenser, and thermometer is added 100 parts of tall oil rosin. The rosin is heated under an inert gas blanket to 150°C, at which time 0.05 parts magnesium oxide and 15 parts nonylphenol are added. The mixture is allowed to cool to 125°C, whereupon 5.1 parts of paraformaldehyde are added. The temperature of this mixture is held at 125°C for one hour, then increased to 180°C. At this time, 0.10 parts of 50% active phosphinic acid is added and stirred in well, after which 3.0 parts of maleic anhydride are added. The mixture is stirred at 180°C for 1 hour; then the temperature is increased to 200°C and 13.0 parts of pentaerythritol are added. The temperature is increased to 250°C, held for 0.5 hours, then raised to 280°C and held for an acid value less than 25. Many modifications and variations of the present invention will be apparent to one of ordinary skill in the art in light of the above teachings. It is therefore understood that the scope of the invention is not to be limited by the foregoing description, but rather is to be defined by the claims appended hereto.

Claims: A high solids solution phenolic composition comprising a mixture of: (a) from 25.0 to 75.0% by weight of resin esters of rosin-phenol condensates, and (b) from 25.0 to 75.0% by weight of a solvent; wherein from 0.2 - 4.0% by weight of said resin esters of a member selected from polyalkanolamines, polyether alcohols, or combinations thereof, is added to said mixture; wherein said polyalkanolamines contain: (1) from 1 to 5 amine groups, (2) from 2 to 7 hydroxyl groups, and (3) where each hydroxyl oxygen atom is separated from an amine nitrogen by 2 carbon atoms; and wherein said polyether alcohols are represented by the chemical structures: where R 1 is hydrogen or C 1 - C 18 alkyl; R 2 is hydrogen, CH 3 , or - CH 2 CH 3 ; R 3 is hydrogen or C 1 - C 4 alkyl; and x is 2 to 15. A composition as claimed in claim 1, comprising a mixture of: (a) from 35.0 to 55.0% by weight of resin esters of rosin-phenol condensates, and (b) from 45.0 to 65.0% by weight of a solvent. A composition as claimed in claim 1 or 2, wherein said solvent is a member selected from aromatic hydrocarbons, aliphatic hydrocarbons, or mixtures thereof. A composition as claimed in claim 1, 2 or 3, wherein from 0.5 - 2.0% by weight of said resin esters of a member selected from polyalkanolamines, polyester alcohols, or combinations thereof is added to said mixture. A composition as claimed in any preceding claim, wherein said polyalkanolamines are represented by the chemical structure: where R 1 is hydrogen, C 1 - C 18 alkyl, or - R 2 - OH; each R 2 is independently -CH 2 CH 2 -, R 3 is C 2 - C 6 alkylene or cycloalkylene; and x is 0 to 3. A composition as claimed in any preceding claim, wherein said polyalkanolamine is a member selected from: triethanolamine, N-ethyldiethanolamine, N,N,N',N'-tetrakis (hydroxypropyl) ethylenediamine, N-methyldiethanolamine, N-butyldiethanolamine, triisopropanolamine, N,N,N',N'-tetrakis(hydroxyethyl)-1,4-cyclohexanediamine, N,N,N',N',N"-pentakis(hydroxypropyl)diethylenetriamine, N,N,N',N'-tetrakis(hydroxyethyl)hexamethylenediamine, or combinations thereof. A composition as claimed in any preceding claim, wherein said polyether alcohol is a member selected from the group consisting of: diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol, dipropylene glycol monoethyl ether, diethylene glycol monobutyl ether, tripropylene glycol, tetraethylene glycol, poly(ethylene glycol) 200, poly(ethylene glycol) 400, and combinations thereof. A gravure printing ink composition comprising a pigment and the composition as claimed in any preceding claim.

Inventors: CREWS EVERETT, HAYDEN J GEORGE, HUTTER G FREDERICK, CREWS, EVERETT, HAYDEN, J. GEORGE, HUTTER, G. FREDERICK
Applicants: WESTVACO CORP, WESTVACO CORPORATION
Application year: 1993
Main classification: C09D11
IPC codes: C09D11, C08G8