Abstract : In this paper, a pigment wetting and dispersing agent modified with adipic acid epoxy acrylate was synthesized. The influencing factors of synthesis were discussed: catalyst, synthesis temperature, and dilution conditions. The application of UV-cured coatings and offset inks was reviewed. Foreword 1, synthesis experiment Table 1 Performance index of PHEA Item Appearance Viscosity mp.s/25°C Acid price mgKOH/g Refractive index ηD25°C Polymer heat resistance 80°C×72h Table II Catalysts Catalytic Effect Types No Catalyst Triethylamine 2-methylpyridine Triphenylphosphine Reaction time h 20 (AV:45) 5.5 4.5 5.0 As can be seen from the above table, the role of the catalyst is quite large, the effect of different catalysts is not the same, the results are also different, in order to control the appearance and the progress of the reaction, the actual application we choose to compound the effect of the catalyst is better, usually choose the three B Amine and 2-methylpyridine, we also chose to use 2-methylpyridine and triphenylphosphine, the effect is slightly worse, the price is not too good. Table III Synthesis temperature control comparison table Reaction temperature control Reaction time appearance Viscosity mp.s/25°C Refractive index nD25°C 2.3 Dilution conditions Table 4 Miscibility of Diluted Monomers Monomer EHA TPGDA HDDA TMPTA LA NPGDA From the above table, it can be seen that the miscibility of monofunctional long chains is not good. The polarity and long chain of the polymers may affect the elongation of the long chains of monomers, and the tangled molecules may not dissolve due to the poor dissolution of the molecules. The specific mechanism remains to be determined. the study. From the point of polymer film formation, transparent polymers are better. After the opaque polymers are formed, they have poor weather resistance and gloss. Therefore, we are all willing to choose a system with good transparency. Usually considering the monomer irritancy and dilution ability, it is better to choose TPGDA. Table 5 Dilution Conditions of Three Solvents at 60°C Item Xylene Butyl Ester Cyclohexanone Miscibility Transparent Transparent Clear Viscosity mp.s/25°C 31000 9000 7000 In addition, when diluting with xylene, temperature control is very important. In the experiment, we found that adding xylene at temperatures higher than 100°C will cause the gelation of the system. We have similar phenomena in dozens of experiments. It is certain that xylene is involved in the reaction. One of the possible reasons may be that a carboxylic acid molecule of adipic acid reacts or catalyzes the formation of a modified xylene resin; it may also be an alkaline catalyst of p-xylene in this environment. Catalyzed formation of xylene resin. The specific mechanism is to be studied. Table 6 Recipe Table Name Components Formula 1 % Quality &
Key words: adipic acid; epoxy acrylate; wetting and dispersing agent; synthesis; application
In UV-curable coatings, the system is a solvent-free system, which determines the viscosity of the system. For primers with pigmented fillers, matt paints, the system is difficult to disperse, and the storage stability of the system is a performance index. Key factor. To obtain a good coating dispersion system, in addition to the resin (oligomer), pigment fillers, and diluting monomers to be matched with each other, it is necessary to properly use a wetting and dispersing agent in order to achieve the intended purpose.
For UV curing systems, two common wetting and dispersing agents are generally used: one is a synthetic long-chain polyester polymer; the other is a silicone-modified coupling agent. 1 General polyester polymer dispersants have a relatively small effect on acrylate systems that are highly polar in nature; silicone-based conjugate dispersants have wetting and dispersing, anti-settling, and increase in coating systems. The adhesion of the coating film, etc., but due to its structure will often change the surface tension, which will affect the UV curing construction (especially the coating). To increase the amount of non-silicone type can play a dispersing role, and too much amount will play a plasticizing effect on the coating and affect the quality of the coating. Therefore, synthesizing an oligomer that can both function as a wetting and dispersing agent and can participate in polymerization and film formation is the best of both worlds. For this purpose, we have developed a wetting and dispersing agent (PHEA) with a carbon-carbon double bond reactive functional group for UV curing systems.
1.1 experimental materials
1. Epoxy resin 828 (Shell, Industrial Grade 1); 2, Acrylic acid (Beijing Oriental Hyacinth Technology Co., Ltd., Industrial Grade 1); 3, Polymerization inhibitor (p-hydroxyanisole); 4, Antioxidant Agent; 5, composite catalyst; 6, adipic acid (Ukraine imported, industrial grade); 7, tripropylene glycol diacrylate (TPGDA, industrial grade, Jiangsu Nantong Litian Chemical Co., Ltd.); 8, photoinitiator I- 1173 (2-Hydroxy-2-methyl-1-phenylacetone, industrial grade, Beijing Yingli Chemical Co., Ltd.); 9, trimethylolpropane triacrylate (TMPTA, industrial grade, Jiangsu Nantong Litian Chemical Co., Ltd. Limited);
1.2 Synthetic process
First add the epoxy resin 828, adipic acid, catalyst, antioxidant, and polymerization inhibitor to the four-necked flask. Stir it for 3 minutes, add nitrogen, and start heating. Control the temperature at 120±2°C for 2 hours. When the value reaches the theoretical design value, the acid temperature is lowered at 110±2° C. after the addition of acrylic acid. When the acid value is less than 5 mgKOH/g, the diluted monomer TPGDA is added and stirred for 20 minutes to discharge the material. You get the product PHEA.
1.3 Performance Index of Synthetic Product PHEA The product performance index synthesized according to the synthetic process of 1.2 is shown in Table 1 below.
Performance 1 # color transparent 85000 2.5 1.5485 no pass; appearance hue using Fe, Co colorimetric method; refractive index is the use of monocular Abbe refractometer; polymer detection by sample and anhydrous methanol 1:4 detection Viscosity was measured using an NDJ-79 rotary viscometer (Shanghai Tongji University Instrument Factory). The acid value was measured by a chemical method.
2, synthesis discussion
2.1 The use of catalyst
For acid-epoxy addition reactions, the reaction is generally slower. The addition of a catalyst promotes the progress of the reaction. Many literatures indicate that the reaction of epoxy groups is highly efficient. We used triethylamine, 2-picoline, and triphenylphosphine for the catalytic contrast reaction. Under the endpoint control acid value (AV) of less than 5 mgKOH/g, we obtained the results in Table II.
Viscosity mp.s/25°C 150000 95000 80000 75000
Appearance 3 # color transparent 2 # color transparent 1 # color transparent 2 # color transparent Note: The above test according to the method of Table 1.
2.2 Synthetic temperature control
The reaction of carboxylic acid and epoxy group in the presence of a catalyst, the reaction temperature does not have to be heated too high, plus the ring opening of the three-membered ring to release a lot of heat, if you do not control the temperature after the synthesis of the stage will cause acrylic double bond Polymerize and gel, resulting in thermal polymerization. 2 Different temperature control will affect the final product index. From Table 3 below, we can see that the temperature control in different stages has a very important impact. From the perspective of reaction time and final performance, the previous stage is controlled at about 120°C. It is appropriate that the latter stage be controlled at about 110°C.
The first segment of 90±2°C The second segment of 110±2°C 10h The yellowish transparent 120000 1.5625
The first segment of 110±2°C The second segment of 110±2°C 7h The water white transparent 95000 1.5520
The first 120±2°C second section 110±2°C 5h Water white transparent 85000 1.5485
The first segment of 120±2°C The second segment of 100±2°C 10h The yellowish transparent 100000 1.5510
For better application of this compound, dilution is usually performed as in conventional polymers, and different dilution conditions of the monomer or solvent may be used for different conditions of use.
2.3.1 Miscibility with Monomers We used miscible dilution tests with different acrylate monomers in a 80:20 ratio of polymer to monomer. The following six monomers were used to test the miscibility. The specific results are shown in Table 4 below.
Miscible Turbid Transparent Clear Transparent Turbid Transparent Note: EHA (isooctyl acrylate), HDDA (1,6 hexanediol diacrylate), LA (dodecyl acrylate), NPGDA (neopentyl glycol diacrylate) .
2.3.2 Solvent dilution
Due to the large polarity of the polymer itself, although the molecular weight is not large, the viscosity of the entire system is relatively large. Sometimes in different application systems, you can choose some solvents to dilute, in order to get low viscosity, we use the common solvent of xylene, butyl acetate and cyclohexanone to dissolve at 60°C. The large polarity of the dissolved, low viscosity, which also coincides with the "similar dissolution" law.
Note: Polymer: Solvent = 90:10
3 . Application Discussion
3.1 Application in UV Coatings
Both UV-cured primers and matt coatings contain filler systems, and it is important to maintain the stability of the coatings themselves. We determine the relevant properties of the coating according to the formulation of the primer in Table 6 below.