Defoamers: Applications in Water-Based Printing Inks

Transcription

1 Surfȳnol Defoamers: Applications in Water-Based Printing Inks Introduction Formulators of water-based inks know that foam is a costly problem that causes difficulties throughout ink-making and printing processes. Problems, such as reduced throughput, result when foam is generated during either the grinding and dispersion step or letdown. During printing, foam leads to a reduction in print quality. To combat problem foam, two proven approaches are recommended for the ink formulator: Eliminate conventional foam-generating surfactants from pigment grind and finished ink formulations. Replace these foamy surfactants with low or nonfoaming Surfȳnol products, such as Surfȳnol CT-, Surfȳnol CT- and Surfȳnol CT- pigment grind aids, and substrate wetting agents such as Surfȳnol, Surfȳnol, Surfȳnol and Surfȳnol SE-F surfactants. Or, utilize Surfȳnol defoamers designed specifically for water-based printing inks. Replacing conventional foam-generating surfactants, such as dioctyl sodium sulfosuccinate (DOSS) and alkylphenol ethoxylates, with a Surfȳnol surfactant will often reduce or eliminate troublesome foam. However, in many cases, foam-generating surfactants are utilized in the manufacture of raw materials, such as pigment dispersions and resins, that the ink formulator cannot control. Therefore, ink formulators often find that the addition of defoamers is their only option. Air Products offers a full line of defoamers (Table ) so that optimal production and printing of water-based inks can be accomplished. When included in water-based ink systems, they offer: Complete foam elimination during grind/ dispersion Rapid initial defoaming and sustained antifoaming No significant viscosity increase No photopolymer plate swell Cost-effective performance FDA compliance for certain food contact end uses Table Application Surfȳnol Defoamer Recommendations for Water-Based Printing Inks Surfȳnol Defoamers (use level % defoamer on total formulation) DF-7 DF- DF-58 DF-6 DF-66 DF-7 DF-75 DF-D/L DF- DF-695 Organo- Ether- Acetylenic- Modified Modified Modified Acetylenic- Organic- Silicone- Silicone- Silicone- Organic- Organic- Acetylenic- Organic- Silicone- Based Based Based Based Based Based Based Based Based Based Grind Dispersion.%.%.%.% Finished Inks Flexo News Flexo Corrugated Packaging Coated Stock Packaging Flexible Film Ink Jets.... Fountain Solutions.. Overprint Varnishes..5.5.

2 Applications Surfȳnol defoamers were evaluated in several model formulations to confirm their benefits in printing inks. The formulations were selected to provide formulators with starting point information on utilizing Surfȳnol defoamers and to illustrate the performance of these products in a wide range of applications. The applications include: pigment grind/dispersion finished inks flexographic newspaper ink gravure publication ink flexographic corrugated packaging ink flexographic flexible packaging ink Surfȳnol defoamers were evaluated for initial and sustained foam control and to determine optimum starting point use-levels for each application. In addition, the effect of Surfȳnol defoamers on viscosity was determined. Within the flexographic newspaper formulation, tests were conducted to determine the effect of Surfȳnol defoamers on photopolymer plate swell. The experimental procedures utilized are summarized in Figure. The performance results from these evaluations are detailed on the following pages. Figure Experimental Procedures Grind Step Pigment grinding and dispersion was performed in a Red Devil shaker with chrome shot ( mm) until a particle size of 5 on a NPIRI scale was achievedabout minutes. Foam Test: Foam volumes were measured in the actual containers in which the grinding occurred. The transparent containers were precalibrated for volume and the initial ink weight was recorded. After grinding, the foam level was determined. A weight-per-volume calculation revealed the ink density of the milled base, which was compared with the density of the unagitated formulation. The defoamers were tested at increasing intervals of. percent in the grind formulations. Optimum performance was represented by the use level that resulted in a density equal to that of the unagitated ink. Finished Inks Initial screening tests were conducted in each model formulation to determine optimum defoamer use-levels, based on sustained defoamer efficacy. Foam Test: The ink samples were thoroughly mixed, then a -gram aliquot was removed and weighed into a two-ounce glass bottle. An equal amount of water was added and the closed bottle was then agitated in a Red Devil Shaker for five minutes. The lid of the bottle was then removed and a stopwatch was started. The time for total dissipation of foam and bubbles was recorded. These samples were not reused. The above test was repeated after hours, one week, one month and two months. An accelerated oven test was used to simulate aging (one day at 9 o C equals one week). Viscosity Test: Samples were thoroughly mixed prior to all viscosity determinations. Measurements were made with a # Zahn cup at 5 o C. Viscosity values were then compared to that of the control (without defoamer). These viscosity tests were run at hours, one week, and one and two month intervals and compared to the defoamer-free control. Photopolymer Plate Swell Test: Letterflex Photopolymer flexographic printing plate on a steel backing (W. R. Grace) was utilized for investigation of plate swell. Two-inch squares were cut out of the printing plate and weighed on an analytical balance. The squares were then immersed into the model flexographic newspaper inks, which contained the defoamers. After hours, the squares were removed from the ink, rinsed with tap water, patted dry with cloth toweling, and reweighed. The weight increase divided by the initial weight determined the percent plate swell. These plate swell values were then compared to those of a control containing no defoamer.

3 Performance Results Pigment Grinding and Dispersion Foam generated during pigment grinding and dispersion results in inefficient grinds and lower throughput. It can also lead to ink printability problems due to entrained air. The model grind formulations used to demonstrate the effectiveness of Surfȳnol defoamers during grinding and dispersion are presented in Figure and Figure. As indicated by their low densities, the control formulations possessed a high degree of foam. However, with the addition of just. to.% on formulation of Surfȳnol DF-58, Surfȳnol DF-6, Surfȳnol DF-D or Surfȳnol DF-695 defoamers, the foam was completely eliminated. The benefits to the dispersion producer are reduced costs through increased throughput and reduced grind times, as well as improved overall quality of the dispersion. Finished Inks For efficient production and printability, a foam-free ink is of paramount importance. Foam will hinder the mixing process and increase the volume of the formulation, thus decreasing throughput. On press, the presence of foam can cause surface defects and loss of gloss, leading to poor print quality. The Surfȳnol line of defoamers is designed specifically to eliminate stubborn surface foam and entrained air without creating other formulation problems. Surfȳnol defoamers provide both excellent knockdown defoaming and long-term antifoaming in water-based flexographic and gravure inks. Figure Pigment Grind/Dispersion Model Formulations Blue Black Phthalo Blue (GS) Presscake 6.% Carbon Black Pearls 5.% Vancryl 68S. Joncryl Isopropanol 5. Water 9..%.% Test Results: Pigment Grind and Dispersion No Foam Foam Complete Foam Elimination Air Products Polymers, L.P. Cabot Corporation Figure Blue Dispersion Foam Density g/ml DF-58 Unagitated Ink Density =.5 g/ml DF-695 Control DF-D % Defoamer (on total formulation) Excellent Knockdown Defoaming in a Printing Ink Dispersion Model Formulation Blue Sunfast Blue 5: Presscake % Joncryl 6. Surfȳnol DF-6 defoamer.. Water.7 5..% viscosity = 5 cps Black Dispersion Foam Density g/ml DF-58 Unagitated Ink Density =.5 g/ml Control DF-695 DF-D % Defoamer (on total formulation) Test Results No Foam.. unagitated density =. g/ml.8.6. Foamy. No Defoamer... % Defoamer

4 Flexographic Newspaper Inks By providing trouble-free defoaming over an extended time period, Surfȳnol DF-6, Surfȳnol DF-75, Surfȳnol DF- and Surfȳnol DF-695 defoamers meet the needs of the water-based flexographic news ink formulator. When evaluated in the model formulations, these Surfȳnol defoamers all exhibited excellent defoaming and antifoam performance (Figure ). In fact, the data presented indicates that all three products provide sustained defoaming efficacy for at least two months (maximum time period tested) at optimum use levels of. to.% on total formulation weight. In addition, unlike many ink additives, the addition of Surfȳnol defoamers does not cause viscosity-build. Another common problem in flexographic newspaper printing is plate swell, which can lead to a reduction in print quality and clarity. This problem is often a direct result of mineral oils or mineral spirits contained in the defoamer. Most Surfȳnol defoamers do not contain mineral oils or mineral spirits and do not cause or contribute to photopolymer plate swell. All of the plate samples tested with Surfȳnol defoamers swelled less than one percent, with no significant increase over the control. Figure Flexographic Newspaper Inks Model Formulations Blue Flexiverse Phthalo Blue (GS) Dispersion 5.% Vancryl Vanwax 5. Water 6..% Test Results: Sustained Defoaming in Flexo News Inks Blue Ink Surfȳnol DF-75 Surfȳnol DF- Surfȳnol DF-695 Blue CONTROL Black Ink Surfȳnol DF-75 Surfȳnol DF- Black hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec) Flexiverse Carbon Black Dispersion.% Joncryl News Flexo F 7.9 Water 7.8.% Use-Level.%.75%.% % Use-Level.%.% Viscosity Increase 5 (seconds) Surfȳnol DF-695 Black CONTROL hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec).5% % Rapid Defoaming and Sustained Antifoaming No Significant Viscosity Increase No Photopolymer Plate Swell Air Products Polymers, L.P. % defoamer on total formulation 5 Increase over control after months aging (# Zahn)

5 Gravure Publication Inks In the publication gravure model formulations (Figure 5), Surfȳnol DF-75, Surfȳnol DF- and Surfȳnol DF-7 defoamers provided excellent defoaming performance. Results indicate that sustained antifoaming for a minimum of two months is achieved with either.5% of Surfȳnol DF-75 or.5% of either Surfȳnol DF- or Surfȳnol DF-7 defoamer. In addition, after two months aging, the Surfȳnol defoamers had no significant effect on viscosity. Figure 5 Gravure Publication Inks Model Formulation Yellow Flexiverse Diarylide Yellow Dispersion.6% Joncryl Joncryl 89. Jonwax 6 5. Water.8.% Test Results: Sustained Defoaming In Gravure Publication Inks Yellow Ink Surfȳnol DF-75 Use-Level.5% Viscosity Increase (seconds) Surfȳnol DF-7.5% Surfȳnol DF-.5% CONTROL % hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec) Initial and Sustained Defoaming Viscosity Buildup: Slight to Insignificant % defoamer on total formulation Increase over control after months aging (# Zahn)

6 Flexographic Corrugated Packaging Inks Additives utilized in corrugated packaging inks must provide cost-effective performance. In the model formulas tested, Surfȳnol DF- defoamer delivered cost-effective performance by providing sustained antifoaming for at least months at.5.% on final formulation. Surfȳnol DF-695 defoamer delivered costeffective performance for 8 weeks at.5%. Both products delivered this performance at a cost of approximately /lb of finished ink (Figure 6). With these products, foam generated during agitation quickly dissipates as it is destabilized by the Surfȳnol defoamers. And incorporation of the Surfȳnol defoamers does not lead to viscosity-build. As is common with red inks, the system did exhibit some increase in viscosity over the two month aging time period. However, this increase was not due to defoamers, since the defoamer-free control formulations exhibited approximately the same viscosity-build. Figure 6 Flexographic Corrugated Packaging Inks Model Formulations Red Black Flexiverse Calcium Lithol Red Carbon Black Pearls 9.% Dispersion 5.% Joncryl 9.8 Vancryl 5 6. Jonwax 6. Vanwax 5. Water. Water..%.% Test Results: Sustained Defoaming in Flexo Corrugated Packaging Inks Red Ink Surfȳnol DF- Surfȳnol DF-695 Red CONTROL Use-Level 5.%.5% % Viscosity Increase 6 (seconds) Black Ink Surfȳnol DF- hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec) Use-Level 5.5% Surfȳnol DF-695.5% Black CONTROL % hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec) Initial and Sustained Defoaming No Significant Viscosity Increase Air Products Polymers, L.P. Cabot Corporation 5 % defoamer on total formulation 6 Increase over control after months aging (# Zahn)

7 Flexographic Flexible Packaging Surfȳnol defoamers effectively eliminated problem foam in the model flexographic flexible packaging inks (Figure 7). Surfȳnol DF-, DF-75 and DF-7 defoamers rendered the ink free of problem foam for at least one month with the addition of.% or.% on final formulation, respectively. Viscosity tests revealed that the Surfȳnol defoamers had no significant effect on formulation viscosity. Many flexible packaging substrates, such as polypropylene, polyethylene and foil, have low surface energies and are therefore difficult to wet-out. The addition of defoamers often exacerbates this problem. For such applications, Air Products offers Surfȳnol DF-7, a mild defoamer that possesses surface tension reduction properties. At a.% use level, Surfȳnol DF-7 defoamer assists in substrate wet-out while providing excellent defoaming performance. FDA Status Conformance to the relevant subsections contained in Part of the Code of Federal Regulations (Food and Drug Administration) is important in many flexible packaging end uses. Surfȳnol DF-75, DF-7 and DF-695 defoamers are compliant with CFR subsections 75., 76.7, 76.8 and 76., while Surfȳnol DF-7 is compliant with The above clearances have certain restrictions and are subject to the enduse and extractive limitations cited in the regulations. Film Integrity Due to their incompatibility, some defoamers can cause wet-out problems and surface defects. Since poor mixing is often the cause, care must be taken to ensure proper incorporation. But if surface defects persist, formulators can alleviate the problem with.5 to % Surfȳnol in a solvent, Surfȳnol, Surfȳnol or Surfȳnol SE-F surfactant. Volatile Organic Compounds (VOCs) Surfȳnol defoamers have been found to contribute only minimally to the VOC emissions of final ink formulations. The values given in Table were derived by employing ASTM test D69 (EPA Reference Method ). These values are for the defoamers by themselves. However, studies in our labs indicate that the VOC contribution of Surfȳnol defoamers could be significantly less when placed in an ink formulation. Figure 7 Flexographic Flexible Packaging Inks Model Formulation Blue Flexiverse Phthalo Blue (GS) Dispersion 9.5% Joncryl Isopropanol.6 Jonwax 6 5. Surfȳnol.9 Water..% Test Results: Sustained Defoaming in Flexo Flexible Packaging Inks Blue Ink Initial and Sustained Defoaming No Significant Viscosity Increase FDA Compliance for Certain Food Contact End Uses Air Products and Chemicals, Inc. (Performance Chemicals Division) % defoamer on total formulation 5 Increase over control after months aging (# Zahn) Table Surfȳnol DF-75 Surfȳnol DF-7 Surfȳnol DF- Surfȳnol DF-7 VOCs of Surfȳnol Defoamers Defoamer VOC (%) Surfȳnol DF-7. Surfȳnol DF Surfȳnol DF-6. Surfȳnol DF-6. Surfȳnol DF-66.6 Surfȳnol DF-7.7 Surfȳnol DF-75. Surfȳnol DF-D 9.5 Surfȳnol DF-L 6. Surfȳnol DF-.8 Surfȳnol DF-695. Use-Level.%.%.%.% CONTROL % hr < wk wk 8 wk 8 wk Defoaming Performance (Foam Life <6 sec) Viscosity Increase 5 (seconds)

8 For More Information If you d like additional information or technical assistance in preparing specific formulations, write or call Air Products and Chemicals, Inc. at the following locations. Air Products and Chemicals, Inc. Performance Chemicals 7 Hamilton Boulevard Allentown, PA Telephone: (Outside U.S./Canada ) Fax: Latin America Air Products and Chemicals, Inc. Latin American Region 7 Hamilton Boulevard Allentown, PA Telephone: Fax: Europe Air Products Nederland B.V. Kanaalweg 5, Box 9 5 GD Utrecht Netherlands Telephone: Fax: Asia Air Products Japan, Inc. -8-9, Toranomon, Minato-Ku Tokyo 5 Japan Telephone: Fax: Air Products Asia, Inc. Rm 557- Hopewell Centre 8 Queen s Road East Wanchai Hong Kong Telephone: Fax: The information in this literature is offered without charge for use by technically qualified personnel at their discretion and risk. All statements, technical information and recommendations are based on tests and data which we believe to be reliable, but their accuracy or completeness is not guaranteed and no warranty of any kind is made. Air Products and Chemicals, Inc., 998 (97) Printed in USA -9857