Phytic acid pretreatment?

The chemical name of phytic acid is phytic acid, its molecular weight is 660.4, and its molecular formula is C 6 H 18 O 24 P 6. Phytic acid is weakly acidic, brown in appearance and easily soluble in water, 95% ethanol, acetone and other solvents. It is an organic phosphoric acid compound extracted from grain [2]. Phytic acid is a hexadentate ligand with six phosphate groups, and the oxygen atom in each phosphate group can be complexed with metal ions as coordination atoms to form a chemically stable five-ring complex [2]. The stable complex formed by phytic acid and metal ions gradually forms a dense protective film on the metal surface, which can effectively prevent the metal from reacting with oxygen in the air, thus protecting the metal from corrosion [3]. The metal surface treated with phytic acid forms a complex, and its chemical properties are similar to those of the coating. At the same time, the active functional groups such as hydroxyl and phosphate in the complex can react with the active functional groups in the coating to form strong chemical bonds, which greatly enhances the adhesion of the coating to the metal surface. At the same time, due to the stable chemical properties of the formed complex, the salt spray resistance of the coating is also improved. Due to the above properties of phytic acid, industrial developed countries have achieved remarkable results by using phytic acid to pretreat metal surface coatings [4].

1 test parts

1. 1 test raw materials

Zhengzhou Yao Di Chemical Products Co., Ltd. HCl Sodium hydroxide from Tianjin Chen Fu Chemical Reagent Factory; Hao Lisen coating Co., Ltd. FC- 109 degreasing powder; FC- 103 Degreaser of Hollysys Coatings Co., Ltd.; Sodium Bromate, Weifang Banghua Chemical Co., Ltd.; Phytic acid (50%), Guangzhou Sanchang Chemical Co., Ltd.; Triethanolamine, Xingtai New Blue Star Technology Co., Ltd.; Tartaric acid, Yantai Derek Bioengineering Co., Ltd.; Calcium nitrate, Qixian Tongli Chemical Co., Ltd.; Copper nitrate, Taiyuan Qunyuan Chemical Co., Ltd.; Potassium sodium tartrate, Grace (Tianjin) Pharmaceutical and Chemical Technology Co., Ltd.; Nickel nitrate, Zhengzhou Shengdanli Chemical Products Co., Ltd.; Sodium benzoate, Tianjin Jinhui Taiya Chemical Reagent Co., Ltd.

1.2 preparation of test reagent

1.2. 1 Preparation of pickling solution

Prepare 1 L 15% hydrochloric acid solution with HCl and deionized water, and add it into a beaker.

1.2.2 preparation of neutralizer

NaOH and deionized water were used to prepare 1 L neutralizer with pH of 14, and added to the beaker.

1.2.3 preparation of degreasing solution

Add 15 g FC- 109 degreaser and 25 g FC- 103 degreaser into a beaker containing 1 L water in turn, and stir evenly until there is no precipitation.

1.2.4 preparation of chemical conversion membrane treatment solution

According to sodium bromate 3.5 g/L, phytic acid 30 mL/L, triethanolamine 16 g/L, tartaric acid 1 g/L, calcium nitrate 1.2 g/L, copper nitrate 0.05g/L, potassium sodium tartrate1.

1.2.5 preparation of blank test solution

Add 1 l deionized water to the beaker.

1.3 test flow

1.3. 1 pretreatment test

Prepare the above prepared chemicals, test A3 steel as the base material according to the flow in Table 1, record the test process, observe the rust return, and determine the rust return area after drying; Then spray alkyd primer and topcoat on A3 steel treated in Test 1 and Test 2, clean the untreated A3 steel, and measure the adhesion and salt spray resistance after natural drying for 24 h (pretreatment test data sheet).