Suyla inceltilebilen alkid reçineleri

Abstract

Organik yüzey kaplama maddesi olarak kullanılan alkid reçinelerin suda çözünebilmesi veya suyla inceltilebilmesi için, alkidin polimer iskeletine, suda çözünebilecek iyonik grupların katılması gerekir. Bu çalışmada, havayla okside olabilen değişik tipte alkid reçineleri, bitkisel yağ ve yağ asitleri ile değişik özelliklerde ve değişik metotlarla elde edilmiştir. Bu alkidlerin eldesinde değişik metotlar kullanılmıştır. Metotlardan biri, yağ asidi, di karboksilli asit ve polihidrik alkol (veya bitkisel yağın polihidrik alkollerle alkolizasinden sonra bir dikarboksilli asit ile ) düşük asit değerlerine kadar esterleştirilmesi, ve daha sonra trimellitikanhidrit ile belirli miktar karboksilli asit grupları serbest kalacak şekilde tekrar esterleştirilmesiyle elde edilmiştir. Bundan başka, yağ asidi, polihidrik alkol, dikarboksilli asit, ve biri düşük temperatürlerde aktif olmayan karboksilli asit grubu, diğer ikisi hidroksil grubu aktif olan dimetilolpropiyonik asit ile karboksilli asit grupları serbest kalacak şekilde direkt esterleşme reaksiyonuyla elde edilmiştir. Yine başka bir metotta, yağ asidi polihidrik alkol ve dikarboksilli asitlerle düşük asitlere kadar esterleştirilip, triınellitik anhidrit ile karboksilli asit grupları serbest kalacak şekilde belirli bir asit değerine kadar tekrar esterleştirildikten sonra stiren ve metilmetakrilat akrilik monomerlerle modifiye edilmesiyle elde edilmiştir. Bu reçineler daha sonra değişik tipte aminlerle nötürleştirilip ve değişik kosolventlerde çözdükten sonra suyla inceltilerek, alkid reçinelerin performansları üzerindeki etkileri araştırılmıştır.

Alkyd resins are made by esterifying vegetable oils ör fatty acids and various monoftmctional and difunctional acids ör anhydrides with a variety of di, tri, and tetra-functional polyols. Depending on the type of oil and fatty acids used, they may be classed as air-drying, that is cross-linked by autoxidation of the fatty acid residues, ör non air-drying resins. Water-soluble alkyd resins are similar to their solvent-borne counterparts. The majör difference is that their formulation is modified to introduce pendant carboxylic acid groups along the polymer backbone. These pendant acid groups can be neutralized with basic coumpoımds to produce water soluble soaps of the alkyd polymer. Most of water-soluble alkyds in commercial use have acid vahıes of 40 to 65 (on resin solids). The majority of polymers used in industrial coatings are of the carboxyl functional type neutralised, producing a quaternary ammonium salt of the polymer which is water reducible. AAAAAAAA COOH + NR3 > AAAAAAA-COO ~ HNR3+ Polymer with basic groups buut into îhe polymer chain have been used for water reducibie coatings. The majority of commercial applications, however, are in the manufacture of cationic electrocoat resins. Neutralizations of these poîymers is usually obtained by using carboxylic acids,e.g. acetic acid. AAAAAAAA-NR2 +R'COOH »AAAAAAAA-NR2 H + R'COO ~" Water soluble ör reducible versions of aîkyd ör poyesters can be produced in a number of ways. viii a) Öne Stage Process Some early water reducible alkyds were made using asinglestage process. İh tfais manufacturing process ali the components of the formulation were charged to the reaction at the start of the process and the reaction stopped at a high acid value to allow neutralisation, and subsequent dilution with water and cosolvent. Using this process polymerisation is halted at a low degree of polymerisation (i.e. incomplete reaction). To compensate for this, and to attempt to form polymers with some degree of molecular complexity a larger qnantity of high functionality (f&v>2) monomers were used, including in some instances, maleinised oils. This gives rise to a complex reaction mixture which will include oligomeric partial esters, free monomer (both acid and alcohol), and variable water solubüity. Another method is to use acid bearing monomer, such as DMPA (2,2-bishydroxymethyl propanoic acid). İn this method ali of the materials (fatty acids, polyols and polycarboxylic acids) are charged together with DMPA. The esterifîcation reaction occurs at 200 ° C. Due to the steric hindrance, the carboxyl group is not reactive under the synthesis conditions; DMPA behaves as a diol with two primary hydroxyl groups.The resultmg resin bears carboxyl groups which can be neutralized in an aqueous medium by amines. b) Two Stage Process An alkyd ör polyester may be produced in a two stage process. Stage öne is, in essence, a normal manufacturing process where the reaction is allowed to proceed to a more normal degree of polymerisation (i.e AV 5-20). However, the polymer is formulated to have a higher hydroxyl value than normal. Stage two is the reaction of part of the residual hydroxyl functionality with polybasic acid, ör more preferably, anhydride, to an acid value of typically 40-70. This second stage proceeds very rapidly at temperatures of 150-180 ° C when anhydrides are used. Anhydrides are preferred because the anhydride ring opening reaction occurs at a lower temperature than the esterification reaction. Thus the reaction can be confined to the addition of the anhydride to the polymer, avoiding the intermolecular crosslinking which can occur by esterification. Of the anhydrides commonly used trimellitic anhydride (TMA) is preferred, because fewer hydroxyl groups are consumed to achieve a given acid value. ix ^««WWA(WO C -JVWWA*WO C f\ +R,N > fi _ + k^COOH k^JcOO ÎT NR3 vwuwuwuO--C ^wwwuw«O C 6 A Carboxyl Amine lonic functional alkyd soluble salt Several water thimıable alkyd resins, based on short oiî, medium oil, long oil length and acıylic modifîcation, using different type of drying oil, polyol, and dibasic acid after solubilized and neutralized with different type of co-solvents and amines were studied. Preparatiom Of Long Oil Alkyd Resim Rt, R2, amd R3 Ali resins were prepared bycharging the ingredients in a 2000 mi 4-necked flask, equipped with an effîcient stirrer, thermometer and inert gas inlet. Heating was performed by means of heating mantle. Drying vegetable oil (2.95 mol soyabean oil in resin Rt and 2.85 mol sıınflower oil in resin R2 and R3 were used) and pentaerythritol (1.54 mol) and PbO (6.10"4 mol) was placed in the reaction vessel.The mixture was heated to 240 °C and maintained at tfais îemperature until the formation of monoglyceride. This was achieved by testing the solubility of samples removed from the reaction mixture in twice its volume of absolute methanol. The reaction mixüıre was then cooled at 150 °C and maleic anhydride (0.02 mol) and dibasic acid (1.94 mol phtalic anhydride in resin RI and R3,1.95 mol isophtalic acid in resin R2 was used) was added followed by a gradual increase of the temperature to 240 ° C. Some reflux solvent (xylene) was added and water of reaction was rernoved by azeotropic distillation.. As soon as an acid vahıe of 8-10 was reached, the mixtare was cooled at 140 ° C and trimellitic anhydride ( 0.71 mol in resin R} and R3 and 0.85 mol in resin R2 was used) was added and temperature was gradually increased to 185 ° C. After an acid vahıe of 55-60 was achieved the reaction mbrture was cooled and thinned with seconder butanol to 80 % nonvoiatile content. Preparatiom Of Mediıım Oiî Styren-Acîyîic Modifled Alkyd Resm R4 To a four necked 2000 mi round-boîtom flask equipped with a rnechanical stirrer, a partial condenser, a total condenser, and a water determination trap were added the folîowing reactants; Tali oil fatty acid X TOFA-2 (2.09 mol), isophtalic acid (1.14 mol)5 trimethylolpropane (1.89 mol) neopentylglycol (1.26 mol). The mixture was gradually heated to 210 °C and stirred under nitrogen atmosphere. The distillate (water) was collected in the water determination trap. Until an acid number of 8 was achieved, the reaction mixture was cooled to 150 °C. The second stage reactant trimellitic anhydride (0.60 mol) and maleic anhydride (0.61mol) were then added. The temperature was gradually raised to 185°C and the reaction was allowed to continue to yield an acid number of 70-75. The resin was then cooled to 145° C. At this temperature, methlmetacrylate (0.6 mol), styren (0.54 mol), tertiary butyl perbenzoate (0.12 mol), di-tertiary butyl peroxide (0.03 mol) were men added over one hour period. After the addition the resin was held at 145 ° C for 45 minutes and dissolved in isopropanol to 80 % nonvolatile content. Preparation Of Medium Oil Aikyd Resin R5 To a four necked 2000 ml round-bottom flask equipped with a mechanical stirrer, a partial condenser, a total condenser, and a water determination trap were added the following reactants; Tall oil fatty acid (TOFA-2) (2.19 mol), phtalic anhydride (2.36 mol), trimethylolpropane (2.95 mol). The mixture was gradually heated to 230 °C and stirred under N2 atmosphere. The distillate (water) was collected in the water determination trap. Until an acid number of 8 was achieved, the reaction mixture was cooled to 150 °C. The second stage reactant trimellitic anhydride (0.63 mol) was then added. The temperature was gradually raised to 185°C and the reaction was allowed to continue to yield an acid number of 50-55. The resin was then dissolved in isopropanol to 80 % nonvolatile content. Preparation Of Short Oil Alkyd Resim Rs To a four necked 2000 ml round-bottom flask equipped with a mechanical stirrer, a partial condenser, a total condenser, and a water determination trap were added the following reactants; sunflower fatty acid (1.99 mol), trimethyloletan (1.41 mol), pentaerythritol (1.03 mol), phtalic anhydride (3.34 mol) dimetylolpropanoic acid (1.06 mol). The mixture was gradually heated to 200 °C and stirred under N2 atmosphere. The distillate (water) was collected in the water determination trap. Until an acid number of 50-55 was achieved, the reaction mixture was cooled to 150 °C. The resin was then dissolved in isopropanol to 80 % nonvolatile content. Preparation Of Short Oil Aflsyd Resim R7 To a four necked 2000 ml round-bottom flask equipped with a mechanical stirrer, a partial condenser, a total condenser, and a water determination trap were added the following reactants; sunflower fatty acid si (1.80 mol), toimethylolpropan (2.06 moİ), neopentylglycol (1.52 mol), isophtalic acid (2.53 mol). The mixture was gradually heated to 210 °C and stirred under N2 atmosphere. The distillate (water) was collected in the water determination trap. Until an acid number of 8 was achieved, the reaction mixture was cooled to 150°C. The second stage reactant trimellitic anhydride (0.73 mol) was then added. The temperature was gradually raised to 185°C and the reaction was allowed to continue to yield an acid number of 50-55. The resin was then dissolved in isopropanol to 80 % nonvolatile content.