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    Home > Coatings News > Paints and Coatings Market > Synthesis and application of polyester resin for dry mixed anti-light powder powder and outdoor solidified dry anti-light powder coating with hydroxyamine

    Synthesis and application of polyester resin for dry mixed anti-light powder powder and outdoor solidified dry anti-light powder coating with hydroxyamine

    • Last Update: 2020-11-18
    • Source: Internet
    • Author: User
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    Abstract:
    high- and low-acid polyester resins for hydroxyamine (Primid) cured dry-mixed anti-light powder coatings have been developed. The mechanical properties, water-resistant boiling and heat resistance of the coating formed by baking after the preparation of high and low acid polyester resin into powder coating and the coating formed by dry mixing by mass ratio of 50:50 were studied.
    results show that:
    the Primid curing system dry and mixed gloss can reach 25 to 35, surface leveling and fineness, mechanical performance and excellent water-resistant cooking performance, can be partially replaced isocyanate triglyceride (TGIC) cured powder coating
    China
    .
    powder coatings have developed rapidly worldwide due to their pollution-free, energy-efficient and near-zero VOC emissions, with a production of 1.6 million t in 2017. At present, domestic thermosolytic powder coatings are mainly divided into indoor powder coatings and outdoor powder coatings, of which indoor powder coatings are mainly epoxy resins, while outdoor powder coatings can be cured with TGIC and Primid.
    When using TGIC curing powder coating, because there is no small molecular by-product generation when baking cured into film, the coating surface is not easy to produce shrink holes, pinholes and other problems, its surface clarity and gloss is high;
    , TGIC system can use catalyst to control reaction speed, and Primid system does not have a suitable catalyst, so the domestic outdoor powder coating mainly uses TGIC as a curing agent. However, due to the physiological toxicity of TGIC, has been banned by the European Union, the domestic has also been listed in 2010 as the elimination of backward production capacity, so TGIC cured powder coatings will gradually be phased out by the market.
    high-gloss powder coatings dominate the market, there is a growing demand for half-light, low-light and lightless products. At present, the preparation of low-light powder coatings such as half-light can mainly use physical and chemical methods, commonly used methods include the addition of detergents, dry mixed light and co-extrusion.
    addition of anti-light agent is mainly acrylic and other resins into polyester resin, resulting in two-phase separation resulting in reduced gloss. Due to the mechanical performance of the system due to the addition of resin, and the cost significantly increased, less application in outdoor powder coatings.
    co-extrusion is mainly high and low acid resin and curing agent through screw extrusion to prepare into a light-absorbing powder coating, in the process of use there is a luster instability phenomenon, its market application is also less. Therefore, the current outdoor powder coating is mainly through dry mixing and de-lighting way to achieve.
    Primid cured dry-mixed anti-light powder coating varieties are relatively few, such as Guangzhou Dynasky NH6381/NH6688, Guanghua GH4406/GH4407, these products in the process of use can not achieve low gloss and good storage stability. In this paper, from the point of view of formulation design, while raising the resin Tg and increasing the active deviation of its high and low acid value resin, the experimental results of Primid curing dry blending gloss can be close to TGIC curing dry mixing light system gloss.
    1 Experimental part
    1.1 Main raw materials
    xin glycol (NPG): Jihua BASF; 2-methyl-1,3 propylene glycol (MPDI): Liaoning Panjin; trihydroxy methamphetamine (TMP): Jilin Petrochemical; 1,4 ethylene glyphate (CHMD): Shanghai Jide Chemistry; glycol (EG), parabens (NTAs): Yangzi Petrochemicals; Interbenzene (IPA): Lotte Korea; Hedic acid (ADA): Jiangsu Haili; Oxalic acid tin (FC2001): Westman Chemicals Private Limited; 30% acetic acid solution, sodium nitrite: analysis pure, national pharmaceutical group.
    Titanium white powder (R-996): industrial grade, Sichuan dragon cocoon; hydroxyacetaminide (T105), leveling agent (GLP588), sabbath: industrial grade, South China Sea chemistry; Qingdao Dongfeng Chemical; Antioxidants for natural gas ovens: industrial grade, Taiwan double key; outdoor TGIC curing dry mixed lighting with high/low acid polyester resin 4805/4806: industrial grade, Anhui Shen jian new materials Co., Ltd.
    1.2 Main experimental equipment
    5L glass reactor: Fischer Scientific, Spain Supply, CAP1000 plus viscosity meter: Broolfield; Pyris-type DSC analyzer: PerKinElmer, INC. TensorI TYPE II Fourier Transform infrared Spectrometer: Bruker.
    twin screw extruder: SLJ-40, Yantai Lingyu; Coffee mill: Q-250A, Shanghai IceDu Electric; Electrostitectronic spraying equipment: HANZHE-901, Hanzhe coating; Electric oven: FDL-100, Binder.
    : Materialtest, Coesfeld; Glossy: Type 4563, Bick; DFT Film Thickener: Positest, DeFelsko, USA; Paint Film Impactor: State-owned Tianjin Instrument Tester Plant; Color Spreader: ColorRerader Konica Minolta Sensing, Inc.; Cup Convex: SP4300, TQC, Netherlands; Artificial Accelerated Aging Tester: Q-lab; Waterproof Material Testing Equipment QSX: Tianjin Construction Instrument Factory; Daxi Shi Pot: GAOBO-13B, Guangdong Gaobo Electric.
    1.3 Preparation of high acid polyester resin (HAV) and low acid polyester resin (LAV
    adding polyols, polyic acids and FC2001 to the 5L spherical glass reactor in table 1, slowly heating up to 240 to 240 255 degrees C and insulation, sampling detection, acid value reached 5 to 15 mg KOH/g cooling to 190 to 220 degrees C to add binary acid (IPA, ADA) acid desealing end, sealing temperature of 230 to 250 degrees C. When the acid value of polyester reaches 50 to 70 mg KOH/g, cool down to 220 to 245 degrees C and vacuum for a period of time, so that the acid value of polyester remains at about 46 to 52 mg KOH/g. Finally, when cooling down to 180 to 220 degrees C, the antioxidant was kept 0.2 to 2h after the discharge, and a high acid polyester resin (HAV) was obtained.
    add polyols, polyic acids and FC2001 to the 5L spherical glass reactor according to the ratio in Table 1, slowly heat up to 240 to 255 degrees C and keep warm, sample detection acid value reached 5 to 15mgKOH/g cool down to 190 to 220 degrees C to add secondary acid (IPA, ADA) for acid unsealing end, sealing end temperature of 230 to 250 degrees C. When the acid value of polyester reaches 30 to 40 mgKOH/g, cool down to 220 to 245 degrees C and vacuum for a period of time, so that the acid value of polyester remains at about 18 to 23 mg KOH/g. Finally, when cooling down to 180 to 220 degrees C, the antioxidant was cast and after 0.2 to 2h was maintained, the low acid polyester resin (LAV) was obtained.
    1.4 Preparation of powder coatings and their coatings
    Powder coatings are prepared according to the basic formula in Table 2, and the process is: ingredients →mixed→ extruded →presses→ crushed→ screened→ powder coating products. The prepared powder coating product is then sprayed with electrostration spray on top of the iron model, then baked and cured in the oven and coated.
    preparation of Primid cured dry mixed light powder coating: the powder coating PD-HAV and PD-LAV with a mass ratio of 1:1 can be fully mixed.
    preparation of TGIC cured dry-mixed anti-light powder coatings: the powder coatings PD-4805 and PD-4806 can be fully mixed with a mass ratio of 1:1.
    1.5 Performance Test
    Test acid values by GB/T 6743-2008, Viscosity by GB/T 9751.1-2008, gb/T 19466.6 2-2004 test glass transition temperature (Tg), test hydroxyl value by GB/T 31412-2015, glialization time by GB/T16995-1997, the temperature is measured at 180 degrees C.
    test adhesion by GB/T 9286-1998, cup convex test by GB/T 9753-2007, gloss of the model measured directly by GB/T 9754-2007, and leveling performance directly by visual inspection To observe the relative thickness of the orange peel, the coating thickness is tested using the Post DFT membrane thickness meter, the impact resistance is tested by GB/T 1732-1993 using the impactor, and the color difference is tested by the color difference reference ASTM D1729-2016 using the color difference meter Color Rerad.
    of the coating refers to the delicateness of the texture of the coating surface after baking, the denser the texture, the more uniform the size represents the finer the finer the degree.
    infrared spectrum: scanning range 600 to 4000cm-1, resolution 4cm-1, test mode is ATR. Artificial accelerated aging performance analysis: wavelength 313nm, light temperature (50±3) degrees C, condensation temperature (40±3) degrees C, light intensity 0.75W/(m2.nm), reference standard ASTMD822/D822M-2013.
    performance test: the use of waterproof material testing equipment after the spray of the iron plate bend 180 degrees to observe whether the coating at the bend cracking.
    natural gas baking experiment: prepare 0.5mL sodium acetate solution and 0.5g sodium nitrite after spraying the model in the oven (oven temperature 180 oC), and then 0.5g of sodium nitrite into the 0.5mL sodium acetate solution, quickly close the oven and bake 15min, and then remove the sample plate after the sample to get the natural gas baking experiment.
    the baking experiment: set the oven temperature to 230 degrees C, then re-place the samples obtained after baking in the oven at 30min, and then remove the models.
    boiling experiment: Add the large saucepan away from the water and bring to the boil, then place the model in it and maintain the boiling state of 2h, see GB/T1733-1993 for testing.
    2 results and discussion
    2.1 high, low acid polyester resin performance
    high, low acid polyester resin performance can be seen in Table 3.
    the high and low acid polyester resins obtained in the experiment met the mass ratio of polyester resin and T105 when prepared into powder coating, respectively, 93/7 and 97/3, and the viscosity was moderate, which was beneficial to improve their level. The Tg of the high and low acid resin is greater than 57 degrees C, and 3d is not blocked at 45 degrees C.
    2.2 Performance of powder coatings and coatings
    the high and low acid polyester resins are prepared into powder coatings, and the two are dried mixed to eliminate light, resulting in Primid cured PD-HAV/PD-LAV dry mixed lighting system model, while comparing the performance of TGIC cured PD-4805/PD-4806 dry mixing system, as shown in Table 4.
    From Table 4, it can be seen that the gel time of high acid polyester resin powder coating is 70 to 90s, the gelization time of low acid polyester resin powder coating is 220 to 260s, the difference between the two gelding time is large, the difference in curing speed forms an inter-permeable network and forms a degliging effect, at this time in the electric oven dry-mixing gloss is 25 to 30, and in the natural gas oven is 2835.
    also observed that the natural gas oven after baking coating showed excellent impact resistance. Electric ovens and natural gas ovens have a chromat difference of about 0.5 when baking, showing good heat resistance and suitable for natural gas oven use. Comparing the TGIC curing model, it can be found that the dry mixing model gloss of Primid curing is slightly higher than that of TGIC curing system, but the difference between the two is very small.
    difference in glazing is mainly due to the fact that the Primid curing system cannot be catalyzed by catalysts, while the TGIC curing system can be accelerated by curing promoters. In terms of fineness, both are good, but a closer look at the Primid curing system model is still not as good as TGIC curing 4805/4806, which may be due to the presence of small molecules such as water during Primid curing process.
    The results of the boiling experiment showed that the high acid polyester resin had excellent water resistance, the gloss of the coating after boiling water was 85, and its preservation rate was more than 90%; For Primid cured dry mixing anti-light model, its gloss can reach 16 to 20, the overall performance of excellent water-resistant cooking performance. Compared with TGIC curing dry mixed lighting system, we can find that the two water after boiling the gloss is close. The results of the
    over-baking experiment show that the high and low acid polyester resins developed in this experiment can be stabilized at more than 90% in the range of 3.5 to 4.0 under the over-baking conditions of 230 degrees C/30min. The color difference and preservation rate of TGIC curing dry mixed anti-light system are better than primid curing system. Since the Primid cured polyester resin is mainly natural gas resistant, the antioxidant is a phosphate class, and the TGIC curing system is a blocked phenol antioxidant and a phosphate antioxidant compound, so the TGIC curing system is better than the experimental Primid curing system.
    2.3 Primid curing system artificial accelerated aging test
    Figure 1 is the artificial aging data of Primid curing dry mixed lighting model.
    from Figure 1, it can be seen that at the beginning of the experiment, the photo protection rate of the model decreased slowly, after artificial aging 200h decreased faster, which is consistent with the performance of conventional weather-resistant resins. The model after artificial aging of 289h and 313h after the preservation rate of 53.5% and 43.1%, respectively, showing that the conventional weather resistance performance is relatively excellent.
    figure 2 is Primid curing dry mixed lighting model in artificial old
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