Study On The Preparation Of Powder Coatings And Its Properties Based On The Polyester Resins

Powder coatings are often used for coating on the surface of metal materials or devices for weather resistance protection or surface decoration.Most of the commercially available powder coatings can only be applied to the final coating of molded devices or products.With the rapid development of industrial technology,some large-scale coating users such as the automotive industry,household appliances industry and other fields to improve production efficiency and reduce costs,the urgent need for a large number of pre-coated steel or steel strip market can be purchased after the stamping or Bend processing to form the required products,directly into the subsequent assembly process or even directly to the end-user use.Therefore,the development of industry technology to powder coating made of impact resistance,bending resistance and other indicators put forward more stringent requirements,continue to carry out high-performance powder coating preparation process and composition of the study has an urgent and important practical significance.Through extensive access to the literature,the polyester resin powder coating with relatively good mechanical properties was selected as the research object.First,a set of basic formula is set up.The technological parameters such as the mixing time,the mixing temperature of the melt extrusion process,the main screw speed,the feed speed and so on,as well as the grinding parameters such as the main grinding and deputy grinding speed of the milling system are studied.The optimum mixing process was as follows: the running time of the high-speed mixer was controlled at about 6 min,the temperature of the twin-screw extruding machine was 110?,the main screw speed was 45 Hz,and the feeding speed was35 Hz.When the powder coating particle size control in the 40 um or so,with the best on the powder rate and leveling match,the corresponding ACM milling system should be set to the process parameters of the main mill speed 5000rad/min,deputy mill speed 2500rad/min.On the basis of the above,by studying the effects of different types of polyester resin and content,curing agent content and modification treatment,the type of pigments and the content of different additives on the performance of powder coatings and coatings,it was found that the coating time of P9335 polyester resin powder coating was the shortest,the impact resistance and bending resistance were the best,and the suitable P9335 polyester resin content should be55%.TGIC curing agent should be appropriate for the amount of 3.85% and modified by the fine treatment,coating leveling,gloss and impact resistance were significantly improved.R996 Rutile Titanium Dioxide is suitable for use as a white pigment for polyester resin powder coatings,while precipitated barium sulfate is used as a filler to improve the melt flow and gloss of the coating due to its minimum oil absorption.Additives can play an important role in regulating the overall performance of the coating-When the amount of L88 levelingagent at 1%,the coating bright and the best leveling;When the content of titanate coupling agent reaches 0.75% of polyester,it can make the inorganic pigment filler get better dispersion effect in organic component;When the amount of edge covering agent is 1%,the ideal covering effect can be achieved.Finally,according to the optimized formula P9335 polyester resin: modified TGIC curing agent: R996 Rutile Titanium Dioxide: precipitation barium sulfate: L88 leveling agent:coupling agent of titanate: edge covering agent ratio is equal to 55: 3.85: 20: 16.24: 1: 0.41:1(the percentage difference is the amount of auxiliary auxiliaries such as benzoin,antioxidant and UV absorbent),The average particle size of the powder coating made with the established preparation process is about 37 um;Coating leveling is good,high gloss,excellent weather resistance,and hardness ? 2H,the substrate surface adhesion up to 0;the coating can withstand 50Kg·cm positive and negative impact test,the coating model by 180°bending test,the bend has not occurred in the coating cracking or peeling phenomenon,Indicating that the polyester resin powder coating prepared in this paper should meet the performance requirements of pre-coated metal sheet coating in engineering practice.