Coating classification: polyurethane coating

Core tip: Introduction: polyurethane coating refers to the coating containing a considerable number of polyester bonds in the paint film, also known as polyurethane coating Polyurethane coating does not necessarily contain polyurethane resin As long as isocyanate or other reactants are used as raw materials, the coatings are called polyurethane coatings, which are mainly used in metal anti-corrosion, aircraft skin, furniture coating, automobile coating, floor paint, road sign paint, etc Classification: polyurethane coatings are classified as follows; (1) According to the composition and film forming mechanism of the coating According to the classification method proposed by the American Society for testing and materials (ASTM), polyurethane is prepared according to its composition and film forming mechanism Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Paint Home News: Introduction: polyurethane paint refers to paint film containing a considerable number of polyester bonds, also known as polyurethane paint Polyurethane coating does not necessarily contain polyurethane resin As long as isocyanate or other reactants are used as raw materials, the coatings are called polyurethane coatings, which are mainly used in metal anti-corrosion, aircraft skin, furniture coating, automobile coating, floor paint, road sign paint, etc Classification: polyurethane coatings are classified as follows; (1) according to the composition and film-forming mechanism of the coatings, according to the classification method proposed by the American Society for testing and materials (ASTM), polyurethane coatings are divided into five categories according to the composition and film-forming mechanism, as shown in Table 1 Table 1 types, characteristics and application types of polyurethane coatings curing - 1 method nco-2 /% pigment dispersibility dry / h abrasion resistance main purpose one component polyurethane oil (astm-1) oxidative polymerization 0 conventional method 0.4-4 general indoor decoration paint, ship, industrial anticorrosion, maintenance paint, floor paint, wood paint wet curing (astm-2) moisture in air < 15 It is difficult to use 0.2-8 alkaline pigment (rh30% or more) for anticorrosive coating of good wood, steel, plastic, floor, cement, mural, underground facilities, closed type (astm-3) heating 0 conventional method 0.5 (below 150 ℃), good insulating paint, especially baking paint two-component catalytic curing type (astm-4) catalyst added to prepolymer 5-10 It is difficult to use alkaline pigment 0.1-2 (rh30%) good ~ very good all kinds of anticorrosive coatings, wear-resistant coatings, leather and rubber coatings (NCO / Oh type, astm-5) polyhydroxy component + additive prepolymer 6-12 polyhydroxy component first grinds with pigment into slurry 2-16 good Various decorative coatings and anti-corrosion coatings, wood, metal (steel, aluminum), plastic, cement, leather, rubber and other coatings (2) according to the type of cyanate ester, according to the type of isocyanate, polyurethane coating is divided into aromatic polyurethane resin coating and aliphatic polyurethane resin coating Aromatic polyurethane resin coating is cheap, UV absorbing, easy to change color and powder It is only suitable for indoor coating or anticorrosive coating TDI, MDI and polymerized PMDI are the main aromatic isocyanates in anticorrosion industry Aliphatic polyurethane resin coating has good weather resistance and no discoloration in outdoor It can be used in automobile maintenance and outdoor high weather resistance anticorrosive coating The main aliphatic isocyanates in the coating industry are HDI, tpdi and H12MDI (3) According to the dispersing medium of the coating, polyurethane coating can be divided into solvent type, solvent-free type, high solid content, water dispersing type, powder coating and light curing type Performance and index: Table 2 and table 3 are the performance indexes of polyester polyurethane coating and epoxy polyurethane coating respectively Table 2 performance index of polyester polyurethane coating dry 7650 polyester / HDI biuret 650 polyester / HDI biuret dry surface [(25 ± 5) ℃] / h 1-22-4 dry [(25 ± 5) ℃] / h 24 48 elastic / mm 1 1 1 impact strength / (kg · cm) 50 adhesion (circle) / level 1 1 1 hardness (swing bar) 0.90.91 distilled water resistance (immersion for 26 days at room temperature) no change salt water resistance (10 %No change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change, no change Cold and hot alternation resistance (100 ℃, 20 min, immediately - 60 ℃, 20 min, and then 10 min at room temperature as a cycle, a total of 100 cycles) elasticity ≤ 10 mm adhesion class 1-2 Table 3 performance index items of epoxy polyurethane coating s01-2 s04-4 s06-2 color and appearance A yellow or brown transparent liquid; B water white or light yellow transparent liquid A same as s01-2; B light gray A same as s01-2; B brown yellow or iron red Surface dry (25 ℃, rh65%) / h ≤ 2 ≤ 1.5 ≤ 1.5 dry (25 ℃, rh65%) / h ≤ 24 ≤ 20 ≤ 10 flexibility / mm ≤ 11 5 impact resistance / cm 50 50 50 hardness (swing bar) ≥ 0.6 ≥ 0.5 ≥ 0.6 chemical resistance (24 h, 10% H2SO4, 10% NH3 · H2O and 10% NaOH aqueous solution) film appearance unchanged film appearance unchanged film appearance unchanged film appearance unchanged Concrete alkalinity (10 d) - no change in coating appearance no change in coating appearance no change in aging resistance (80 ℃, 4 d) no change in coating appearance no change in coating appearance no change in cold and hot alternation (20 cycles) - no change in coating appearance no change in coating appearance ① excellent physical and mechanical properties, especially wear resistance, adhesion, high decoration and tenacity Polyurethane coating is the best wear-resistant coating with the highest elongation at break; polyurethane coating is suitable for most substrates (such as metal, wood and glass , plastics, leather, etc.) have excellent adhesion Compared with epoxy resin, it has poor adhesion to metal, but strong adhesion to rubber and concrete materials It has excellent color and light retention performance, good glossiness, fullness and brightness, especially the weather resistance of aliphatic polyurethane coating is better, which is equivalent to the decoration of acrylic resin coating, far more resistant than epoxy resin coating Good weather and decoration performance ② Good corrosion resistance Compared with epoxy coating, polyurethane coating has stronger acid resistance and water resistance, while their alkali resistance, solvent resistance and oil resistance are equivalent ③ The curing temperature range is wide Polyurethane coating can be cured at room temperature or baking at low temperature It can be crosslinked and cured at low temperature (- 5 ℃ or even lower), and the coating has good performance and fast drying, which most coatings do not have, such as epoxy coating curing slowly below 10 ℃ ④ Wide range of temperature resistance Polyurethane coating can resist low temperature to - 40 ℃ and high temperature to 250 ℃ (for example, polyurethane electrophoretic coating made of hdi-tdi trimer) ⑤ The film is nontoxic after curing The polyurethane coating after thorough curing is non-toxic and is used for food, beer packaging and inner wall of storage tank Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,