HYDROXYL-TERMINATED POLYESTER RESIN, PREPARATION METHOD THEREFOR AND USE THEREOF

Abstract

A hydroxyl-terminated polyester resin, a preparation method therefor and use thereof. The hydroxyl-terminated polyester resin is composed of the following raw materials in parts by mass: 25-50 parts of a diol, 40-70 parts of a dibasic acid, 0.1-2 parts of glycidyl tertcarbonate, 0.5-4 parts of a hydroxylation reagent, 0.08-0.3 parts of a catalyst and 0.2-0.5 parts of an antioxidant. The acid value of the polyester resin is 1-8 mgKOH/g, the hydroxyl value is 20-30 mgKOH/g, the melt viscosity at 200° C. is 9000-13000 mPa.Math.s, the reactivity at 180° C. is 410-520 s, the glass transition temperature is 53-59° C., and the softening point is 101-106° C.

Claims

1. A hydroxyl-terminated polyester resin comprising the following components in parts by mass: 25-50 parts of diol, 40-70 parts of dibasic acid, 0.1-2 parts of glycidyl tertcarbonate, 0.5-4 parts of a hydroxylation reagent, 0.08-0.3 parts of a catalyst and 0.2-0.5 parts of an antioxidant.

2. The hydroxyl-terminated polyester resin according to claim 1, wherein the hydroxyl value of the hydroxyl-terminated polyester resin is 20-30 mgKOH/g, and the acid value of the hydroxyl-terminated polyester resin is 1-8 mg KOH/g.

3. The hydroxyl-terminated polyester resin according to claim 1, wherein the melt viscosity of the hydroxyl-terminated polyester resin at 200° C. is 9,000-13,000 mPa s.

4. The hydroxyl-terminated polyester resin according to claim 1, wherein the diol is selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, ethylene glycol, 2-ethyl-2-butyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, and combinations thereof.

5. The hydroxyl-terminated polyester resin according to claim 1, wherein the dibasic acid is aromatic dibasic acid, aliphatic dibasic acid, or a combination thereof.

6. The hydroxyl-terminated polyester resin according to claim 1, wherein the hydroxylation reagent is selected from the group consisting of 1,2,3,4,5-pentitol, 1,2,3,4,5,6-hexanehexol, 2,2-dihydroxymethyl-butanol, and combinations thereof.

7. The hydroxyl-terminated polyester resin according to claim 1, wherein the catalyst is an organic tin catalyst.

8. A method for preparing the hydroxyl-terminated polyester resin according to claim 1, comprising the following steps of: (a) carrying out a polycondensation reaction of the diol, dibasic acid, glycidyl tertcarbonate, and catalyst in an inert atmosphere to obtain a primary polymer; (b) when the acid value of the primary polymer obtained in step (a) is 10-25 mgKOH/g, vacuumizing and then continuing the polycondensation reaction to obtain a condensation polymer; and (c) when the acid value of the condensation polymer obtained in step (b) is 8-15 mgKOH/mg, carrying out a hydroxylation reaction until the acid value of the product obtained by the hydroxylation reaction is 1-8 mgKOH/g and the hydroxyl value of the product is 20-30 mgKOH/g, at this moment, adding an oxidant, and then mixing to obtain the hydroxyl-terminated polyester resin.

9. The method for preparing the hydroxyl-terminated polyester resin according to claim 8, wherein the degree of vacuum of the vacuumizing in step (b) is in a range of 0.08 MPa to 0.1 MPa.

10. A coating comprising the hydroxyl-terminated polyester resin of claim 1.

11. A coating comprising the hydroxyl-terminated polyester resin prepared according to the method of claim 8.

12. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the diol is selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, ethylene glycol, 2-ethyl-2-butyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,6-hexanediol, and combinations thereof.

13. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the dibasic acid is aromatic dibasic acid, aliphatic dibasic acid, or a combination thereof.

14. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the hydroxylation reagent is selected from the group consisting of 1,2,3,4,5-pentitol, 1,2,3,4,5,6-hexanehexol, 2,2-dihydroxymethyl-butanol, and combinations thereof.

15. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the catalyst is an organic tin catalyst.

16. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the temperature of the polycondensation reaction of step (a) is in a range of 230° C. to 240° C.

17. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the time of the polycondensation reaction of step (a) is in a range of 3 hours to 5 hours.

18. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the time of the polycondensation reaction of step (b) is in a range of 50 minutes to 120 minutes.

19. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the temperature of the hydroxylation reaction in step (c) is in a range of 215° C. to 230° C. and the time of the hydroxylation reaction in step (c) is in a range of 1 hour to 3 hours.

20. The method for preparing the hydroxyl-terminated polyester resin of claim 8, wherein the temperature of the mixing in step (c) is in a range of 200° C. to 230° C. and the time of the mixing in step (c) is in a range of 10 minutes to 40 minutes.

Description

DETAILED DESCRIPTION OF THE EXAMPLES

[0039] To make the inventive purpose, technical solutions and its technical effect of the present disclosure more clear, the present disclosure will be further described in detail in combination with specific examples. It should be understood that specific examples described in the description are only to explain the present disclosure but not intended to limit the present disclosure.

[0040] According to compositions of hydroxyl-terminated polyester resins of examples 1-6 and contrasts 1-2 in Table 1, diol, glycidyl tertcarbonate, aromatic dibasic acid, aliphatic dibasic acid and a catalyst were added into a reaction kettle in the proportion, nitrogen was introduced for protection, temperature was risen to about 182-184° C. by a program, at this moment, esterified water started to be generated and discharged by distillation, then the above mixture continued to be slowly heated to 230-240° C., heat preservation was performed for 2-5h at 230-240° C. until more than 90% of esterified water was discharged, and the system became clear and transparent. The acid value was tested as 10-25 mgKOH/g. Vacuum polycondensation was performed, the vacuum degree was adjusted to 0.08-0.1 MPa for reaction, wherein the vacuum polycondensation reaction lasted for 80 min in examples 1-6, the vacuum polycondensation reaction lasted for 118 min in contrast 1, the vacuum polycondensation reaction lasted for 90 min in contrast 2, the acid value was tested as 8-15 mgKOH/g, the temperature was reduced to 215° C.-230° C. for hydroxylation reaction, and heat preservation was performed for 1-3h at this temperature. When the acid value was 1-8 mgKOH/g, the hydroxyl value was 20-30 mgKOH/g and the melt viscosity at 200° C. was 9,000-13,000 mPa.Math.s, the polycondensation reaction was completed. The temperature was reduced to 200° C.-230° C. to obtain a melting condensation polymer. An antioxidant was added into the melting condensation polymer, the above materials were stirred and mixed for 10-40 min, discharged and cooled to obtain the hydroxyl-terminated polyester resin.

TABLE-US-00001 TABLE 1 Compositions of hydroxyl-terminated polyester resins in examples 1-6 and contrasts 1-2 Components (in parts by mass) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Contrast 1 Contrast 2 First feed Diol Neopentyl glycol 25  33.8  35  27 25.8 37 32  33 Ethylene glycol 8 — — 4 8 — 4 — 1,4-cyclohexanedimethanol 2 1.5 8 4 3 2 — 4 2-ethyl-2-butyl-1,3-propanediol — 5   — — 0.5 — — 3 1,2-propanediol — — 1 2.5 — — — — 2-methyl propanediol 1 — — — — 0.7 — — 1,6-hexanediol — 1   — — — — 3 — Glycidyl tertcarbonate 1 0.2 1 0.3 0.3 0.1 — — Aromatic Terephthalic acid 55  58   55  57 58 57 57  55 dibasic acid Isophthalic acid 5 — 5 3 — 2 4 — Fatty 1,4-succinic acid — 2   — — 5 — — — dibasic acid 1,6-hexanedioic acid 4 — — — — — — 4 1,10-decanedioic acid — 1.5 4 — — — — — Dodecanedioic acid — — — 1 — 3 — — 1,4-cyclohexanedicarboxylic acid — — 2 2 — — 2 — Catalyst Monobutyl tin oxide   0.09 —   0.09 0.09 — —   0.09 — Monobutyl tin triisooctanoate —  0.23 — — 0.23 0.23 — 0.23 Second feed (hydroxylation reaction) Hydroxylation 2,2-dihydroxymethyl butanol — — — 1 — 0.8 1 2.3 reagent 1,2,3,4,5-pentitol (xylitol)   0.88 1.5 — — 0.6 0.6 — — 1,2,3,4,5,6-hexanehexol (sorbitol) — —   1.2 0.7 0.5 — — — Third feed (antioxidant added) Antioxidant Antioxidant 1076   0.23  0.23 — 0.23 — —   0.23 — Antioxidant 1010 — —   0.23 — 0.23 0.23 — 0.23 Antioxidant DSTP   0.23  0.23   0.23 0.23 0.23 0.23   0.23 0.23

[0041] Contrast 3: according to compositions of the hydroxyl-terminated polyester resin of example 1, diol, glycidyl tertcarbonate, aromatic dibasic acid, aliphatic dibasic acid and a catalyst were added into a reaction kettle in the proportion, nitrogen was introduced for protection, temperature was risen to about 184° C. by a program, at this moment, esterified water started to be generated and discharged by distillation, then the above mixture continued to be slowly heated to 235° C., heat preservation was performed for 3.5 h at 235° C. until more than 90% of esterified water was discharged, and the system became clear and transparent. The acid value was tested as 10-25 mgKOH/g. Polycondensation was performed for 50 min-120 min until the temperature was 230° C., the hydroxylation reaction was performed, heat preservation was performed for 2h at this temperature so as to complete the polycondensation reaction, and then the temperature was reduced 215° C. to obtain a melting condensation polymer, an antioxidant was added into the melting condensation polymer, and the above materials were stirred and mixed for 30 min, discharged and cooled to obtain the hydroxyl-terminated polyester resin.

[0042] Performance testing was carried on the hydroxyl-terminated polyester resins prepared in examples 1-6 and contrasts 1-3, in which:

[0043] The measurement method of the hydroxyl value of the hydroxyl-terminated polyester resin was as follows: the prepared hydroxyl-terminated polyester resins were weighed in corresponding weights according to Table 2 and put in a 250 mL conical flask, then 20 mL of tetrahydrofuran was added into the flask to dissolve the hydroxyl-terminated polyester resin, then 25 mL of catalyst solution (10 g/L 4-dimethylaminopyridine in tetrahydrofuran solution) and 10 mL of acetylation solution (1 L of tetrahydrofuran containing 125 mL of acetic anhydride) were respectively measured with a pipette and added into the conical flask to be evenly shaken, and underwent standing for 5 min at room temperature; then 20 mL of hydrolysis solution (prepared in a volume ratio of tetrahydrofuran to distilled water being 4:1) was added, evenly shaken (sometimes turbidity occurred) and kept for 30 min at room temperature, and shaken once every 5 min; 25 mL of tetrahydrofuran and 5 drops of phenolphthalein solution (prepared in a proportion of 10 g phenolphthalein/1 L anhydrous ethanol) were added, titration was performed using 0.35N potassium hydroxide-ethanol solution, and the end point is reached when the color of the solution became red from colorless. A blank solution was prepared for titration test to test the acid value of the hydroxyl-terminated polyester resin.

[0044] Calculation of hydroxyl value:

[00001]$\mathrm{OH}=\frac{V_2-V_1*N*56.1}{M}+\mathrm{AV}$

[0045] wherein, V.sub.1: the volume of the potassium hydroxide solution consumed by the hydroxyl-terminated polyester resin;

[0046] V.sub.2: the volume of the potassium hydroxide solution consumed by the blank solution;

[0047] N: the concentration of the potassium hydroxide solution;

[0048] M: the mass of the hydroxyl-terminated polyester resin sample;

[0049] AV: the acid value of the hydroxyl-terminated polyester resin sample.

TABLE-US-00002 TABLE 2 Sampling quality table of hydroxyl value measurement samples of resins Hydroxyl value range (mgKOH/g) <15 15~25 25~50 50~100 100~200 200~400 Sample mass (g) 10 5 3 1.5 1 0.5 Precision (g) 0.001 0.001 0.001 0.001 0.0001 0.0001

[0050] The measurement method of the acid value of the hydroxyl-terminated polyester resin was as follows: 5 g of hydroxyl-terminated polyester resin was weighed and put into a conical flask with accurate of 1 mg, 30 mL of methylbenzene-ethanol mixed solvent was added so that the hydroxyl-terminated polyester resin was completely dissolved (if being not dissolved at room temperature, it could be properly heated under the environment with good ventilation, but the solution needed to be cooled to room temperature before titration). 3-5 drops of phenolphthalein indicator solution were added into the sample solution, then the ethanol solution of potassium hydroxide was immediately titrated until red color appeared, the end point was reached if the red color did not disappear in 30 s, and the volume of the consumed potassium hydroxide solution was recorded. A parallel blank test was performed, and steps were the same as described above.

[0051] Calculation of acid value:

[00002]$\mathrm{Acid}\mathrm{value}=\frac{\left(V-V_0\right)*N*56.1}{m}$

[0052] wherein, m: the mass of the hydroxyl-terminated polyester resin sample;

[0053] V: the volume of the potassium hydroxide solution consumed by the hydroxyl-terminated polyester resin;

[0054] V.sub.0: the volume of the potassium hydroxide solution consumed by the blank test;

[0055] N: the concentration of the potassium hydroxide solution.

[0056] The performance test results of the hydroxyl-terminated resin are as shown in table 3.

TABLE-US-00003 TABLE 3 Performance test results of hydroxyl-terminated resins in examples 1-6 and contrasts 1-3 Index Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Contrast 1 Contrast 2 Contrast 3 Hydroxyl value 23.3 25.0 24.7 29.1 27.2 21.4 24.3 26.7 28.5 mgKOH/g Viscosity 9270 12150 12420 10820 11140 10660 10210 11480 2740 (200° C.)/mPa .Math. s Reactivity 492 419 441 435 457 514 483 406 816 (180° C.)/s Glass transition 55.3 54.8 53.4 57.5 58.6 54.1 55.7 56.2 50.8 temperature/° C. Softening 103 102 101 105 106 102 103 104 96 temperature/° C.

[0057] Result analysis: it can be seen from examples 1-6 and contrasts 1-3 described above that polyester resins with corresponding viscosity ranges are obtained, the vacuumizing time in examples 1-6 is less than that of the contrasts 1-2, and the contrast 3 is not vacuumized, so the viscosity and glass transition temperature of the obtained polyester resin are both low, indicating that the cross-linking density of the obtained polyester resin is low, and there are problems such as poor storage stability of the polyester resin.

[0058] 264 g of polyester resin obtained in examples 1-6 and contrasts 1-3, 36 g of curing agent B1530 (purchased from Evonik Degussa Specialty Chemicals (Shanghai) Co., Ltd.), 165 g of titanium dioxide (purchased from Panzhihua Dongfang Titanium Industry Co., Ltd.), 6 g of leveling agent (purchased from Ningbo Nanhai Chemical Co., Ltd.), 3 g of brightener 701 (purchased from Ningbo Nanhai Chemical Co., Ltd.), 3 g of defoamer 703 (purchased from Zhaoqing Shiying Coating Materials Co., Ltd.) were respectively weighed, and then the powder coating was prepared by melting, extruding, sheeting and crushing with a screw extruder and passing through a 180 mesh powder sieve.

[0059] Product Effect Test:

[0060] The powder coatings obtained in examples 1-6 and contrasts 1-3 were sprayed onto a metal plate subjected to surface treatment (phosphatization) with an electrostatic spray gun, with a film thickness being about 70 μM. The coating was cured at 200° C./15 min, and then performance test was carried out.

[0061] Test the gloss in accordance with GB/T9754-2007;

[0062] Conduct gelling time test in accordance with GB/T16995-1997;

[0063] Conduct impact test in accordance with T/GDTL 004-2018;

[0064] Conduct horizontal flow test in accordance with GB6554-1986;

[0065] Conduct lamp A accelerated aging test in accordance with GB/T14522-2008.

[0066] The performance test results of powder coating layers prepared by examples 1-6 and contrasts 1-3 are as shown in Table 4.

TABLE-US-00004 TABLE 4 Performance test results of power coating layers prepared in examples 1-6 and contrast 1-3 Component Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Contrast 1 Contrast 2 Contrast 3 Coating layer Smooth Smooth Smooth Smooth Smooth Smooth Smooth Un-smooth Smooth appearance Gloss % 90.9 90.5 91.5 90.4 91.9 91.3 90.4 90.8 91.2 Gelling time at 705 575 621 603 645 736 790 532 964 180° C./s Impact/70 cm Qualified in Qualified in Qualified in Qualified in Qualified in Qualified in Crack Qualified in Crack both both both both both both in both both in both positive and positive and positive and positive and positive and positive and positive and positive and positive and negative negative negative negative negative negative negative negative negative Horizontal flow/m 30 28.5 29.5 29 29.5 30.5 31 27.5 35 Lamp A * 1,000 h 99.9 100 99.9 99.8 100 100 98.6 99.3 70.2 (gloss retention (%)) Lamp A * 2,000 h 85.3 87.1 87.9 88.5 85.7 86.4 68.5 72.6 28.4 (gloss retention (%))

[0067] Result analysis: the powder coating layers prepared in examples 1-6 have better mechanical property and more excellent weather resistance compared with the conventional powder polyester coating layers in contrasts 1-3. After accelerated ageing under lamp A for 1,000h, almost all the light retention rate can be maintained at 100% without light gloss; after accelerated ageing under lamp A for 2,000h, the light retention rate can be maintained at more than 85%; all the light retention rates are better, which can better meet the requirement of the market.

[0068] The above examples are preferred embodiments of the present disclosure, but embodiments of the present disclosure are not limited to the above examples, other any variations, modifications, replacements, combinations and simplifications made without departing from the spirit and principle of the present disclosure should be included within the protective scope of the present disclosure.