Polyester resin for boiling-resistant high-leveling powder coating with high bio-based content

Abstract

The invention relates to the technical field of multifunctional polyester materials, and discloses polyester resin for a high-bio-based content boiling-resistant high-leveling powder coating, which is prepared by the following steps: preparing a carboxylated bio-based organic silicon monomer which is a carboxylated bio-based organic silicon monomer M1 or a carboxylated bio-based organic silicon monomer M2; on the basis of an esterification reaction mechanism, hydroxylated nano SiO2 is subjected to surface modification treatment through a carboxylated bio-based organic silicon monomer, and the bio-based organic-inorganic hybrid water-resistant modifier is prepared. Polyatomic acid and polyhydric alcohol containing 2, 5-furandicarboxylic acid components are used as synthetic monomers, a bio-based organic-inorganic hybrid water-resistant modifier is added, and the semi-crystalline polyester resin with high bio-based content is prepared through catalytic esterification and vacuum polycondensation reaction, and the semi-crystalline polyester resin can significantly improve the water resistance and the leveling performance of the powder coating, so that the water resistance and the leveling performance of the powder coating are greatly improved. The stable storage can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of multifunctional polyester materials, in particular to a polyester resin for high-biobased content boiling-resistant high-leveling powder coating. Background Art

[0002] After years of development, powder coatings have made great progress, and their market share and application areas have continued to expand. However, powder coatings themselves also have structural defects, which are caused by polyester resin, the most critical component of powder coatings.

[0003] Powder coatings mainly use amorphous polyester resins. A notable feature of amorphous polyester resins is that their glass transition temperature is positively correlated with melt viscosity, that is, the greater the viscosity, the higher the glass transition temperature. Powder coatings, on the one hand, expect polyester resins to have a higher glass transition temperature to ensure storage stability, and on the other hand, expect polyester resins to have lower melt viscosity, so that when powder coatings are cured, polyester resins have better wetting properties for pigments and fillers, thereby obtaining a coating with better leveling properties.

[0004] In addition, since the molecular structure of polyester resin contains more ester bonds, the water resistance of polyester powder is poor.

[0005] In addition, monomers such as polyols and polyacids used in polyester resins are generally derived from fossil raw materials such as petroleum, coal, and natural gas. In the context of the increasing depletion of petrochemical resources and increasingly serious environmental pollution, they are not in line with the concept of sustainable development. Summary of the invention

[0006] The invention provides a semi-crystalline polyester resin with a high bio-based content. The semi-crystalline polyester resin can significantly improve the water resistance and leveling performance of a powder coating and can be stably stored.

[0007] A polyester resin for high-biobased content, boiling-resistant and high-leveling powder coating, comprising the following raw materials in parts by weight: 30-40 parts by weight of neopentyl glycol, 4-6 parts by weight of 2-butyl-2-ethyl-1,3-propanediol, 5-15 parts by weight of 1,6-hexanediol, 1-2 parts by weight of trimethylolpropane, 20-40 parts by weight of terephthalic acid, 3-10 parts by weight of adipic acid, 10-30 parts by weight of 2,5-furandicarboxylic acid, 1-5 parts by weight of a catalyst, 1-5 parts by weight of a capping agent, 0.5-3 parts by weight of a stabilizer, 1-5 parts by weight of a biobased organic-inorganic hybrid water-resistant modifier, and 0.1-3 parts by weight of a composite antioxidant;

[0008] The preparation method of the bio-based organic-inorganic hybrid water-resistant modifier is as follows: using the esterification reaction mechanism, the surface of hydroxylated nano-SiO2 is modified by carboxylated bio-based silicone monomer M1 or carboxylated bio-based silicone monomer M2.

[0009] Preferably, the preparation method of the carboxylated bio-based silicone monomer M1 is: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, a strong acid catalyst catalyzes the addition reaction of 1 molar equivalent of the olefinic functional group of vinyl pentamethyldisiloxane with 1.01-1.05 molar equivalents of the carboxyl functional group of 2,5-furandicarboxylic acid to prepare the carboxylated bio-based silicone monomer M1.

[0010] Preferably, the preparation method of the carboxylated bio-based silicone monomer M2 is: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, a strong acid catalyst catalyzes the addition reaction of 1 molar equivalent of the alkenyl functional group of heptaisobutylallyl polysilsesquioxane with 1.01-1.05 molar equivalents of the carboxyl functional group of 2,5-furandicarboxylic acid to prepare the carboxylated bio-based silicone monomer M2.

[0011] Preferably, the strong acid catalyst is one of sulfuric acid, p-toluenesulfonic acid and fluoroboric acid.

[0012] Preferably, the end-capping agent is trimellitic anhydride or adipic anhydride.

[0013] Preferably, the catalyst is monobutyltin oxide 4100 or stannous oxalate.

[0014] Preferably, the stabilizer is triphenyl phosphite.

[0015] Preferably, the composite antioxidant includes antioxidant 168 and antioxidant 1010.

[0016] Beneficial effects:

[0017] The present invention uses 2,5-furandicarboxylic acid as a bio-based raw material to synthesize two carboxylated bio-based organosilicon monomers, and based on the esterification reaction mechanism, the surface of hydroxylated nano-SiO2 is modified by the carboxylated bio-based organosilicon monomers to obtain a bio-based organic-inorganic hybrid water-resistant modifier;

[0018] A bio-based raw material 2,5-furandicarboxylic acid is used to replace a part of the petrochemical-based raw material (terephthalic acid) as a synthetic monomer of the polyester resin, and the polyester system is modified by a bio-based organic-inorganic hybrid water-resistant modifier to prepare a polyester resin for a high-biobased content, water-boiling-resistant and high-leveling powder coating. The powder coating prepared in this way not only has excellent water-boiling resistance, but also achieves simultaneous improvement of leveling performance and storage stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the chemical structural formula of carboxylated bio-based organosilicon monomer M1;

[0020] Figure 2 is the chemical structural formula of carboxylated bio-based organosilicon monomer M2;

[0021] Figure 3 It is a bar graph of the test results of powder coating performance. DETAILED DESCRIPTION

[0022] Embodiment 1:

[0023] A semi-crystalline polyester resin with a high bio-based content, the formula of which is shown in Table 1;

[0024] Table 1 Formulation of semi-crystalline polyester resin with high bio-based content

[0025] Raw material components Feed mass m(g) Neopentyl glycol NPG 36.25 2-Butyl-2-ethyl-1,3-propanediol BEPD 5.37 1,6-Hexanediol HDO 10.42 Trimethylolpropane (TMP) 1.73 Terephthalic acid PTA 34.61 Adipic acid DOA 7.56 2,5-Furandicarboxylic acid FDCA 21.03 Monobutyltin oxide 4100 1.57 Trimellitic Anhydride TMA 2.68 Triphenyl phosphite 0.55 Bio-based organic-inorganic hybrid water-resistant modifier 1.85 Antioxidant 168 0.28 Antioxidant 1010 0.18

[0026] The preparation method of the bio-based organic-inorganic hybrid water-resistant modifier is as follows: using the esterification reaction mechanism, the surface of the hydroxylated nano-SiO2 is modified by carboxylating the bio-based organic silicon monomer;

[0027] The carboxylated bio-based organosilicon monomer is a carboxylated bio-based organosilicon monomer M1 or a carboxylated bio-based organosilicon monomer M2;

[0028] The preparation method of the carboxylated bio-based organosilicon monomer M1 is as follows: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, p-toluenesulfonic acid catalyzes the addition reaction of the olefin functional group of 1 molar equivalent of vinyl pentamethyldisiloxane and the carboxyl functional group of 1.02 molar equivalent of 2,5-furandicarboxylic acid to generate the carboxylated bio-based organosilicon monomer M1, whose chemical structure is as follows: Figure 1 As shown, the specific preparation steps are as follows: under the protection of nitrogen, 1.7 g of vinyl pentamethyl disiloxane, 1.6 g of 2,5-furandicarboxylic acid and 50 mL of tetrahydrofuran are added to a three-necked flask, the temperature is raised to 30°C to dissolve, and then 0.5 g of p-toluenesulfonic acid is added dropwise to the three-necked flask, the temperature is raised to 60°C, stirred for reaction for 6 hours, cooled to room temperature, the solvent is removed by rotary evaporation, and the carboxylated bio-based organosilicon monomer M1 is obtained after vacuum drying;

[0029] The nuclear magnetic resonance hydrogen spectrum of the carboxylated bio-based silicone monomer M1 is characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 0.03 (s, 9H), 0.08 (s, 6H), 1.44-1.45 (d, 3H), 4.35-4.41 (m, 1H), 7.32-7.36 (d, 2H);

[0030] The preparation method of the carboxylated bio-based organosilicon monomer M2 is as follows: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, p-toluenesulfonic acid catalyzes the addition reaction of 1 molar equivalent of the alkenyl functional group of heptaisobutylallyl polysilsesquioxane with 1.03 molar equivalent of the carboxyl functional group of 2,5-furandicarboxylic acid to generate the carboxylated bio-based organosilicon monomer M2, whose chemical structure is as follows: Figure 2 As shown, the specific preparation steps thereof differ from those of the carboxylated bio-based organosilicon monomer M1 only in that: 1.7 g of vinyl pentamethyl disiloxane is replaced by 8.6 g of heptaisobutylallyl polysilsesquioxane;

[0031] The nuclear magnetic resonance hydrogen spectrum of the carboxylated bio-based silicone monomer M2 is characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 0.53-0.65 (m, 14H), 0.89-0.91 (d, 21H), 0.94-0.96 (d, 21H), 1.13- 1.15 (d, 2H), 1.35-1.36 (d, 3H), 1.68-1.79 (m, 7H), 4.71-4.76 (m, 1H), 7.36-7.42 (d, 2H).

[0032] Embodiment 2:

[0033] A method for preparing a semi-crystalline polyester resin with a high bio-based content comprises the following steps:

[0034] Step 1: Preparation of bio-based organic-inorganic hybrid water-resistant modifier: 1g carboxylated bio-based organosilicon monomer, 5g hydroxylated nano-SiO2 and 50mL N,N-dimethylformamide were added to a three-necked flask, 2mL of concentrated sulfuric acid was slowly added to the three-necked flask under mechanical stirring, the temperature was raised to 80°C and reacted for 5h, washed with deionized water, rotary evaporated and dried to obtain a bio-based organic-inorganic hybrid water-resistant modifier;

[0035] Step 2: According to the formula of the semi-crystalline polyester resin with high bio-based content in Table 1, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol and trimethylolpropane are first put into a reaction kettle, heated to melt, filled with nitrogen and stirred, and then terephthalic acid, adipic acid, 2,5-furandicarboxylic acid and monobutyltin oxide 4100 are added, and the temperature is raised to 240° C. to keep the reaction until the acid value reaches 13.7 mgKOH / g;

[0036] Step 3: Cool down to 220°C and add triphenyl phosphite and trimellitic anhydride, start stirring, and keep warm at 220°C until the acid value reaches 41.5 mgKOH / g; turn on the vacuum pump, slowly evacuate at 220°C to a vacuum degree of -0.1 MPa, maintain for 3 hours, so that the acid value is 24.3 mgKOH / g;

[0037] Step 4: Cooling to 200° C., adding a bio-based organic-inorganic hybrid water-resistant modifier, antioxidant 168 and antioxidant 1010, and maintaining the reaction for 40 minutes to obtain a semi-crystalline polyester resin with a high bio-based content;

[0038] The acid value is tested according to GB / T 6743-2008 "Determination of partial acid value and total acid value of polyester resins for plastics, paints and varnishes".

[0039] When the carboxylated bio-based organosilicon monomer is the carboxylated bio-based organosilicon monomer M1, the prepared polyester resin is recorded as semi-crystalline polyester resin I with high bio-based content;

[0040] When the carboxylated bio-based silicone monomer is the carboxylated bio-based silicone monomer M2, the prepared polyester resin is recorded as semi-crystalline polyester resin II with high bio-based content.

[0041] Embodiment 3:

[0042] Application of a semi-crystalline polyester resin with a high bio-based content: According to the formula in Table 2, a semi-crystalline polyester resin with a high bio-based content, a curing agent TGIC, a leveling agent 588, a brightener 701, benzoin and titanium dioxide are put into a twin-screw extruder (the temperature in the front zone is 120°C, the temperature in the rear zone is 105°C, and the rotation speed is 35r / min), and a powder coating is obtained by premixing, extruding, cooling, crushing, grinding and sieving; the powder coating is sprayed on a tinplate by electrostatic spraying, and is cured at 200°C / 15min.

[0043] Table 2 Powder coating formulation

[0044]

[0045]

[0046] When the semi-crystalline polyester resin with high bio-based content is semi-crystalline polyester resin with high bio-based content I, the prepared powder coating is recorded as powder coating I;

[0047] When the semi-crystalline polyester resin with high bio-based content is semi-crystalline polyester resin with high bio-based content II, the prepared powder coating is recorded as powder coating II.

[0048] Performance Test:

[0049] The powder coating was sprayed on the tinplate by electrostatic spraying. After curing in an oven at 200°C for 15 minutes, the sample was taken out and the coating properties were tested after the sample was cooled to room temperature. The results are shown in Table 3.

[0050] Table 3 Performance test results of powder coatings

[0051]

[0052]

[0053] The powder coatings in the comparative example and Example 3 differ only in that the formulation of the semi-crystalline polyester resin with a high bio-based content does not contain a bio-based organic-inorganic hybrid water-resistant modifier;

[0054] According to the test data in Table 3, Figure 3 ,Through comprehensive analysis of the above experimental results, the following conclusions can be drawn:

[0055] The semi-crystalline polyester resin with high bio-based content prepared by the present invention can not only significantly improve the leveling performance of powder coatings, but also can be stably stored;

[0056] In addition, the semi-crystalline polyester resin with a high bio-based content is modified by using the bio-based organic-inorganic hybrid water-resistant modifier developed and synthesized by the present invention, and the powder coating prepared thereby achieves the beneficial technical effect of effectively improving the water boiling resistance.

Claims

1. A polyester resin for high bio-based content, boiling-resistant and high-leveling powder coating, characterized in that: The invention comprises the following raw materials in parts by weight: 30-40 parts by weight of neopentyl glycol, 4-6 parts by weight of 2-butyl-2-ethyl-1,3-propanediol, 5-15 parts by weight of 1,6-hexanediol, 1-2 parts by weight of trimethylolpropane, 20-40 parts by weight of terephthalic acid, 3-10 parts by weight of adipic acid, 10-30 parts by weight of 2,5-furandicarboxylic acid, 1-5 parts by weight of a catalyst, 1-5 parts by weight of a capping agent, 0.5-3 parts by weight of a stabilizer, 1-5 parts by weight of a bio-based organic-inorganic hybrid water-resistant modifier, and 0.1-3 parts by weight of a composite antioxidant; The preparation method of the bio-based organic-inorganic hybrid water-resistant modifier is as follows: using the esterification reaction mechanism, the surface of the hydroxylated nano-SiO2 is modified by carboxylated bio-based organic silicon monomer M1 or carboxylated bio-based organic silicon monomer M2; The chemical structure of carboxylated bio-based silicone monomer M1 is: The chemical structure of carboxylated bio-based silicone monomer M2 is 2. The polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 1, characterized in that: The preparation method of the carboxylated bio-based silicone monomer M1 is as follows: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, a strong acid catalyst catalyzes an addition reaction between 1 molar equivalent of the olefin functional group of vinyl pentamethyldisiloxane and 1.01-1.05 molar equivalent of the carboxyl functional group of 2,5-furandicarboxylic acid to prepare the carboxylated bio-based silicone monomer M1.

3. The polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 1, characterized in that: The preparation method of the carboxylated bio-based silicone monomer M2 is as follows: based on the Markovnikov rule of olefin electrophilic addition orientation reaction, a strong acid catalyst catalyzes an addition reaction between 1 molar equivalent of the alkenyl functional group of heptaisobutylallyl polysilsesquioxane and 1.01-1.05 molar equivalent of the carboxyl functional group of 2,5-furandicarboxylic acid to prepare the carboxylated bio-based silicone monomer M2.

4. A polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 2 or 3, characterized in that: The strong acid catalyst is one of sulfuric acid, p-toluenesulfonic acid and fluoroboric acid.

5. The polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 1, characterized in that: The end-capping agent is trimellitic anhydride or adipic anhydride.

6. The polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 1, characterized in that: The catalyst is monobutyltin oxide 4100 or stannous oxalate.

7. The polyester resin for high bio-based content boiling resistance and high leveling powder coating according to claim 1, characterized in that: The stabilizer is triphenyl phosphite.

8. The polyester resin for high bio-based content boiling-resistant high-leveling powder coating according to claim 1, characterized in that: The composite antioxidant includes antioxidant 168 and antioxidant 1010.

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