CN113999378B - Polyester resin for powder coating with low cost and excellent thermal transfer printing effect and preparation method thereof - Google Patents
Polyester resin for powder coating with low cost and excellent thermal transfer printing effect and preparation method thereof Download PDFInfo
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- CN113999378B CN113999378B CN202111559629.6A CN202111559629A CN113999378B CN 113999378 B CN113999378 B CN 113999378B CN 202111559629 A CN202111559629 A CN 202111559629A CN 113999378 B CN113999378 B CN 113999378B
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- 238000000576 coating method Methods 0.000 title claims abstract description 65
- 229920001225 polyester resin Polymers 0.000 title claims abstract description 61
- 239000004645 polyester resin Substances 0.000 title claims abstract description 61
- 239000011248 coating agent Substances 0.000 title claims abstract description 58
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000000843 powder Substances 0.000 title claims description 45
- 230000000694 effects Effects 0.000 title abstract description 17
- 238000010023 transfer printing Methods 0.000 title abstract description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 32
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims abstract description 27
- YDEXUEFDPVHGHE-GGMCWBHBSA-L disodium;(2r)-3-(2-hydroxy-3-methoxyphenyl)-2-[2-methoxy-4-(3-sulfonatopropyl)phenoxy]propane-1-sulfonate Chemical compound [Na+].[Na+].COC1=CC=CC(C[C@H](CS([O-])(=O)=O)OC=2C(=CC(CCCS([O-])(=O)=O)=CC=2)OC)=C1O YDEXUEFDPVHGHE-GGMCWBHBSA-L 0.000 claims abstract description 24
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims abstract description 18
- VERAMNDAEAQRGS-UHFFFAOYSA-N butane-1,4-disulfonic acid Chemical compound OS(=O)(=O)CCCCS(O)(=O)=O VERAMNDAEAQRGS-UHFFFAOYSA-N 0.000 claims abstract description 10
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 claims abstract description 9
- SLCVBVWXLSEKPL-UHFFFAOYSA-N neopentyl glycol Chemical compound OCC(C)(C)CO SLCVBVWXLSEKPL-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000006227 byproduct Substances 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims description 44
- 239000002253 acid Substances 0.000 claims description 35
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 34
- 229920000642 polymer Polymers 0.000 claims description 28
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 26
- 229920005610 lignin Polymers 0.000 claims description 26
- 238000010438 heat treatment Methods 0.000 claims description 23
- 239000002994 raw material Substances 0.000 claims description 22
- 239000011780 sodium chloride Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 230000020477 pH reduction Effects 0.000 claims description 15
- 239000007787 solid Substances 0.000 claims description 15
- 238000004821 distillation Methods 0.000 claims description 13
- 238000012544 monitoring process Methods 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 11
- 230000001276 controlling effect Effects 0.000 claims description 10
- 238000007599 discharging Methods 0.000 claims description 9
- 238000003825 pressing Methods 0.000 claims description 9
- LCFVJGUPQDGYKZ-UHFFFAOYSA-N Bisphenol A diglycidyl ether Chemical compound C=1C=C(OCC2OC2)C=CC=1C(C)(C)C(C=C1)=CC=C1OCC1CO1 LCFVJGUPQDGYKZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000003963 antioxidant agent Substances 0.000 claims description 8
- 230000003078 antioxidant effect Effects 0.000 claims description 8
- 239000003054 catalyst Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 8
- BGYHLZZASRKEJE-UHFFFAOYSA-N [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxy]-2,2-bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxymethyl]propyl] 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical group CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CCC(=O)OCC(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)=C1 BGYHLZZASRKEJE-UHFFFAOYSA-N 0.000 claims description 6
- BVFSYZFXJYAPQJ-UHFFFAOYSA-N butyl(oxo)tin Chemical group CCCC[Sn]=O BVFSYZFXJYAPQJ-UHFFFAOYSA-N 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 238000005886 esterification reaction Methods 0.000 claims description 6
- 238000006068 polycondensation reaction Methods 0.000 claims description 6
- 229920000728 polyester Polymers 0.000 claims description 6
- 238000004321 preservation Methods 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 239000011812 mixed powder Substances 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 238000003786 synthesis reaction Methods 0.000 abstract description 3
- 238000006116 polymerization reaction Methods 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 20
- 238000001723 curing Methods 0.000 description 9
- 238000012546 transfer Methods 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000003973 paint Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 229920001732 Lignosulfonate Polymers 0.000 description 1
- -1 [ methyl-beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] pentaerythritol ester Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002981 blocking agent Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- QDHFHIQKOVNCNC-UHFFFAOYSA-N butane-1-sulfonic acid Chemical compound CCCCS(O)(=O)=O QDHFHIQKOVNCNC-UHFFFAOYSA-N 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000013035 low temperature curing Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000005028 tinplate Substances 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
- C08G63/688—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur
- C08G63/6884—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur derived from polycarboxylic acids and polyhydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/82—Preparation processes characterised by the catalyst used
- C08G63/85—Germanium, tin, lead, arsenic, antimony, bismuth, titanium, zirconium, hafnium, vanadium, niobium, tantalum, or compounds thereof
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Polyesters Or Polycarbonates (AREA)
- Paints Or Removers (AREA)
Abstract
Provides a polyester resin for 60/40 mixed powder coating with low cost and excellent thermal transfer printing effect and a preparation method thereof. The polyester resin is mainly obtained by polymerization of sodium lignin sulfonate, hydrochloric acid, neopentyl glycol, diethylene glycol, trimethylolpropane, terephthalic acid and 1, 4-butanedisulfonic acid. A large amount of sodium lignin sulfonate serving as a byproduct of papermaking is used in the synthesis of the polyester resin, so that the hardness of the polyester resin is improved, the cost is reduced, the activity of the polyester resin is obviously improved by using 1, 4-butanedisulfonic acid end capping, full curing is realized under the curing condition of 160 ℃/12min, and the transfer printing effect is clear.
Description
Technical Field
The invention relates to the field of powder coatings, in particular to a polyester resin for a powder coating with low cost and excellent thermal transfer printing effect and a preparation method thereof.
Background
As a 100% solid powdery paint, the powder paint has the characteristics of no solvent, no pollution, recoverability, environmental protection, labor intensity reduction, high mechanical strength of a coating film and the like, and is widely applied in the current surface coating field.
The polyester resin for the common 60/40 mixed powder coating has wider application in the powder coating, particularly has larger occupation in the heat transfer powder coating, but the common 60/40 mixed polyester resin has softer chain segments and general carboxyl end group activity, and has more customer complaints due to the phenomenon of sticking paper caused by insufficient curing when being used in the heat transfer powder coating.
In addition, sodium lignin sulfonate is a byproduct of papermaking waste liquid, the yield is high, the sodium lignin sulfonate is generally only used in the field of low-end dispersing agents, the added value is low, and the problem of how to improve the added value of lignin sulfonate and realize comprehensive utilization of the sodium lignin sulfonate is solved.
Therefore, there is a need to develop a polyester resin for powder coating with low cost and excellent thermal transfer effect and a preparation method thereof to solve the above-mentioned problems.
Disclosure of Invention
Therefore, the invention provides a low-cost polyester resin with excellent thermal transfer printing effect for powder coating, which mainly comprises the following raw materials in parts by mole:
wherein, besides the raw materials, the polyester resin is also added with a catalyst and an antioxidant in the preparation process,
wherein the catalyst is monobutyl tin oxide, and the dosage of the catalyst is 0.1-0.15% of the total mass of the raw materials;
wherein the antioxidant is antioxidant 1010, namely tetra [ methyl-beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] pentaerythritol ester, and the dosage of the antioxidant is 0.2-0.5% of the total mass of the raw materials.
The sodium lignin sulfonate is a paper making byproduct, and is a common commercial product and can be purchased from Feihuang chemical industry Co., ltd.
Wherein the appearance of the polyester resin is light yellow transparent particles, the acid value is 48-54mgKOH/g, and the softening point is 112-120 ℃.
The invention also provides a preparation method of the polyester resin for the powder coating, which comprises the following steps:
(1) Adding 20-30 mol parts of sodium lignin sulfonate into a first reaction container, adding a proper amount of water, stirring, heating to dissolve completely, and then regulating the pH of the solution to 3-4 for full acidification reaction;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still between 3 and 4, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree to be between-0.095 and-0.098 Mpa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 18-21%, and performing filter pressing to separate solid lignin sulfonic acid from the solution to obtain solid lignin sulfonic acid for standby;
(3) Adding lignin sulfonic acid obtained in the step (2), 15-25 mol parts of neopentyl glycol, 5-12 mol parts of diethylene glycol, 10-15 mol parts of terephthalic acid and a catalyst accounting for 0.1-0.15% of the total mass of the raw materials into a second reaction container, heating to 185-190 ℃ and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 50-65mgKOH/g, 8-15 mol parts of bisphenol A diglycidyl ether and 3-6 mol parts of trimethylolpropane are added, then the temperature is raised to 220-225 ℃, and the reaction is carried out for a period of time;
(5) When the acid value of the polymer in the system is reduced to 25-35mgKOH/g, adding an antioxidant with the dosage of 0.2-0.5% of the total mass of the raw materials, and starting a vacuum system to carry out vacuum polycondensation reaction;
(6) When the acid value of the system polymer is reduced to 12-18mgKOH/g, releasing vacuum, adding 10-17 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 220-225 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 48-54mgKOH/g, discharging, cooling, crushing and granulating to obtain the polyester resin.
In the step (1) or (3), the reaction vessel is a reaction kettle.
Wherein in the step (1), the temperature is raised to 80-85 ℃.
In the step (1), a proper amount of hydrochloric acid solution is gradually added dropwise into the solution to adjust the pH value of the solution to 3-4.
In the step (1), the hydrochloric acid is industrial hydrochloric acid with the mass concentration of 31%.
Wherein in the step (1), the acidification reaction time is 2-3h.
In the step (2), the filter pressing is to separate solid lignin sulfonic acid from a liquid sodium chloride solution through plate-and-frame filter pressing.
Wherein in the step (3), the temperature is raised to 185-190 ℃ at a temperature raising rate of 25-30 ℃/h.
Wherein in the step (4), the temperature is raised to 220-225 ℃ at a temperature raising rate of 6-8 ℃/h.
Wherein, in the step (5), the vacuum degree is controlled to be between-0.096 and-0.098 Mpa.
In the step (7), the discharging is high-temperature discharging when the discharging is hot, and the cooling is performed by using a steel belt with condensed water.
The invention also provides a powder coating, which contains the polyester resin for the powder coating.
Wherein the powder coating is a 60/40 mixed powder coating.
The invention also provides a powder coating, which is prepared from the powder coating.
The invention has the following beneficial technical effects:
1. the invention mainly uses sodium lignin sulfonate, hydrochloric acid, neopentyl glycol, diethylene glycol, trimethylolpropane, terephthalic acid and 1, 4-butanedisulfonic acid to polymerize to obtain the polyester resin suitable for the 60/40 mixed powder coating. The acid value of the obtained polyester resin is 48-54mgKOH/g, and the softening point is 112-120 ℃.
2. In the synthesis of the polyester resin, a large amount of sodium lignin sulfonate is used, the sodium lignin sulfonate is firstly subjected to acidification treatment to obtain lignin sulfonic acid, and the lignin sulfonic acid is used as a functional component to be synthesized into the novel 60/40 polyester resin by matching with neopentyl glycol, diethylene glycol, terephthalic acid, bisphenol A diglycidyl ether, trimethylolpropane, 1, 4-butanesulfonic acid and the like, so that the hardness of the polyester resin is improved, the cost is reduced, and a novel method is provided for recycling the sodium lignin sulfonate with high added value. Specifically, sodium lignin sulfonate and hydrochloric acid are adopted to adjust to acidity to obtain lignin sulfonic acid, then the lignin sulfonic acid is concentrated through reduced pressure distillation and plate and frame filter pressing to obtain solid lignin sulfonic acid, and then the lignin sulfonic acid, dihydric alcohol, dibasic acid and trihydric alcohol are polymerized to obtain the polyester resin.
3. The 1, 4-butanedisulfonic acid is used as a blocking agent and the sulfonic acid group is used as a blocking group in the synthesis of the polyester resin, so that the activity of the polyester resin is obviously improved, the polyester resin and the E-12 epoxy resin are fully cured under the curing condition of 160 ℃/12min at low temperature, and the transfer printing effect is clear.
4. The chain segment of the polyester resin contains a large amount of lignin sulfonic acid and bisphenol A diglycidyl ether which are rigid raw materials, so that the rigidity and the adhesion force with a substrate part of the polyester resin are improved.
5. The coating film obtained after the low-temperature curing of the polyester resin has high hardness, pencil hardness of 2H, no adhesion to transfer paper, clear transfer, excellent adhesion to tinplate, and other performances of the coating film can completely meet various requirements of powder coating, and meanwhile, the raw material cost of the polyester resin is obviously reduced, so that a novel method is provided for comprehensive utilization of a papermaking byproduct sodium lignin sulfonate.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
A preparation method of polyester resin for powder coating comprises the following steps:
(1) Adding 21 molar parts of sodium lignin sulfonate into a first reaction kettle, adding a proper amount of water, stirring, heating to 84 ℃ to completely dissolve the sodium lignin sulfonate, gradually dropwise adding a proper amount of hydrochloric acid solution to adjust the pH of the solution to 3, and performing full acidification reaction for 2.5h;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still 3, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree at-0.095 Mpa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 19%, and performing plate and frame filter pressing to separate solid lignin sulfonic acid from liquid sodium chloride solution to obtain solid lignin sulfonic acid for later use;
(3) Adding lignin sulfonic acid, 17 mole parts of neopentyl glycol, 11 mole parts of diethylene glycol, 12 mole parts of terephthalic acid and monobutyl tin oxide accounting for 0.12% of the total mass of the raw materials obtained in the step (2) into a second reaction kettle, gradually heating to 189 ℃ at a heating rate of 29 ℃/h, and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 52mgKOH/g, adding 9 mole parts of bisphenol A diglycidyl ether and 5 mole parts of trimethylolpropane, then heating to 223 ℃ at the heating rate of 7 ℃/h, and preserving heat for reaction for a period of time;
(5) When the acid value of the polymer in the system is reduced to 29mgKOH/g, adding an antioxidant 1010 accounting for 0.3 percent of the total mass of the raw materials, starting a vacuum system to carry out vacuum polycondensation reaction, and controlling the vacuum degree to be-0.097 Mpa;
(6) When the acid value of the system polymer is reduced to 17mgKOH/g, releasing vacuum, adding 12 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 223 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 52mgKOH/g, discharging at high temperature while the polymer is hot, cooling by using a steel belt with condensed water, crushing and granulating to obtain the polyester resin.
The obtained polyester resin had the appearance of pale yellow transparent particles, an acid value of 52mgKOH/g and a softening point of 115 ℃.
Example 2
A preparation method of polyester resin for powder coating comprises the following steps:
(1) Adding 28 molar parts of sodium lignin sulfonate into a first reaction kettle, adding a proper amount of water, stirring, heating to 81 ℃ to completely dissolve the sodium lignin sulfonate, gradually dropwise adding a proper amount of hydrochloric acid solution to adjust the pH of the solution to 4, and performing full acidification reaction for 2.8 hours;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still 4, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree at-0.095 Mpa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 20%, and performing plate and frame filter pressing to separate solid lignin sulfonic acid from liquid sodium chloride solution to obtain solid lignin sulfonic acid for later use;
(3) Adding lignin sulfonic acid, 20 mole parts of neopentyl glycol, 10 mole parts of diethylene glycol, 13 mole parts of terephthalic acid and monobutyl tin oxide accounting for 0.14% of the total mass of the raw materials obtained in the step (2) into a second reaction kettle, gradually heating to 188 ℃ at a heating rate of 29 ℃/h, and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 64mgKOH/g, 13 mole parts of bisphenol A diglycidyl ether and 4 mole parts of trimethylolpropane are added, then the temperature is raised to 221 ℃ at the heating rate of 8 ℃/h, and the reaction is kept for a period of time;
(5) When the acid value of the polymer in the system is reduced to 26mgKOH/g, adding an antioxidant 1010 accounting for 0.4 percent of the total mass of the raw materials, starting a vacuum system to carry out vacuum polycondensation reaction, and controlling the vacuum degree to be-0.098 Mpa;
(6) When the acid value of the system polymer is reduced to 17mgKOH/g, releasing vacuum, adding 13 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 221 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 53mgKOH/g, discharging at high temperature while the polymer is hot, cooling by using a steel belt with condensed water, crushing and granulating to obtain the polyester resin.
The obtained polyester resin had the appearance of pale yellow transparent particles, an acid value of 53mgKOH/g and a softening point of 113 ℃.
Example 3
A preparation method of polyester resin for powder coating comprises the following steps:
(1) Adding 27 mole parts of sodium lignin sulfonate into a first reaction kettle, adding a proper amount of water, stirring, heating to 83 ℃ to completely dissolve the sodium lignin sulfonate, gradually dropwise adding a proper amount of hydrochloric acid solution to adjust the pH of the solution to 3, and performing full acidification reaction for 2.2h;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still 3, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree at-0.096 Mpa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 21%, and performing plate and frame filter pressing to separate solid lignin sulfonic acid from liquid sodium chloride solution to obtain solid lignin sulfonic acid for later use;
(3) Adding lignin sulfonic acid, 22 mole parts of neopentyl glycol, 6 mole parts of diethylene glycol, 11 mole parts of terephthalic acid and monobutyl tin oxide accounting for 0.14% of the total mass of the raw materials obtained in the step (2) into a second reaction kettle, gradually heating to 189 ℃ at a heating rate of 27 ℃/h, and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 63mgKOH/g, adding 12 mole parts of bisphenol A diglycidyl ether and 5 mole parts of trimethylolpropane, then heating to 222 ℃ at a heating rate of 6 ℃/h, and preserving heat for reaction for a period of time;
(5) When the acid value of the polymer in the system is reduced to 32mgKOH/g, adding an antioxidant 1010 accounting for 0.4 percent of the total mass of the raw materials, starting a vacuum system to carry out vacuum polycondensation reaction, and controlling the vacuum degree to be-0.096 Mpa;
(6) When the acid value of the system polymer is reduced to 15mgKOH/g, releasing vacuum, adding 11 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 222 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 49mgKOH/g, discharging at high temperature while the polymer is hot, cooling by using a steel belt with condensed water, crushing and granulating to obtain the polyester resin.
The prepared polyester resin had the appearance of pale yellow transparent particles, an acid value of 49mgKOH/g and a softening point of 114 ℃.
Example 4
A preparation method of polyester resin for powder coating comprises the following steps:
(1) Adding 24 molar parts of sodium lignin sulfonate into a first reaction kettle, adding a proper amount of water, stirring, heating to 81 ℃ to completely dissolve the sodium lignin sulfonate, gradually dropwise adding a proper amount of hydrochloric acid solution to adjust the pH of the solution to 4, and performing full acidification reaction for 3 hours;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still 4, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree at-0.097 Mpa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 18%, and performing plate and frame filter pressing to separate solid lignin sulfonic acid from liquid sodium chloride solution to obtain solid lignin sulfonic acid for later use;
(3) Adding lignin sulfonic acid, 19 mole parts of neopentyl glycol, 11 mole parts of diethylene glycol, 13 mole parts of terephthalic acid and monobutyl tin oxide accounting for 0.11% of the total mass of the raw materials obtained in the step (2) into a second reaction kettle, gradually heating to 185 ℃ at a heating rate of 29 ℃/h, and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 60mgKOH/g, adding 10 mole parts of bisphenol A diglycidyl ether and 4 mole parts of trimethylolpropane, then heating to 225 ℃ at a heating rate of 8 ℃/h, and preserving heat for reaction for a period of time;
(5) When the acid value of the polymer in the system is reduced to 31mgKOH/g, adding an antioxidant 1010 accounting for 0.5 percent of the total mass of the raw materials, starting a vacuum system to carry out vacuum polycondensation reaction, and controlling the vacuum degree to be-0.097 Mpa;
(6) When the acid value of the system polymer is reduced to 17mgKOH/g, releasing vacuum, adding 16 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 225 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 51mgKOH/g, discharging at high temperature while the polymer is hot, cooling by using a steel belt with condensed water, crushing and granulating to obtain the polyester resin.
The prepared polyester resin had the appearance of pale yellow transparent particles, an acid value of 51mgKOH/g and a softening point of 118 ℃.
Comparative example 1
A commercially available 60/40 polyester resin for powder coating was used as comparative example 1, model number SJ5B, acid value 49mgKOH/g, purchased from Anhui Shenjian New Material Co., ltd.
Comparative example 2
A commercially available 60/40 polyester resin for powder coating was used as comparative example 2, model SJ5B, acid value 49mgKOH/g, purchased from Anhui Shenjian New Material Co., ltd. Comparative example 2 differs from comparative example 1 in that in the preparation of the powder coating, the curing condition of comparative example 1 was 160 ℃/12min, whereas the curing condition of comparative example 2 was 180 ℃/15min.
Preparing a powder coating:
the powder coatings of examples 1-4 and comparative examples 1-2 were prepared using the polyester resins of examples 1-4 and comparative examples 1-2, respectively, according to the following powder coating formulation, wherein the contents of the components are in parts by weight:
preparing a powder paint coating:
the powder coatings of examples 1-4 and comparative examples 1-2 were prepared by mixing the materials uniformly, extruding with a twin-screw extruder, tabletting, crushing, and then crushing and sieving the tablets according to the formulation of the powder coatings of examples 1-4 and comparative examples 1-2, respectively. Then, the powder coatings of examples 1-4 and comparative examples 1-2 were sprayed onto the surface-treated aluminum plate substrate using an electrostatic spray gun, respectively, with a film thickness of 70-80 μm, and cured at 160 ℃/12min (as an exception, the curing conditions of comparative example 2 were changed to 180 ℃/15 min), to obtain the coating coatings of examples 1-4 and comparative examples 1-2. After the aluminum plate and the coating are cooled, uniformly coating glue for thermal transfer printing on the surface of the coating, and then covering and wiping the wood grain transfer printing paper; baking the treated aluminum plate for 10min under 160 ℃ baking condition; after cooling, the transfer paper was peeled off to obtain coating films of the wood grain powder coatings of examples 1 to 4 and comparative examples 1 to 2.
Coating performance test:
and (3) coating index detection: according to GB/T21776-2008, powder coating and detection standard guideline of coating thereof;
and (3) hardness detection: paint film hardness was tested according to GB/T6379-2006, paint and varnish Pencil method.
The results of the resulting coating performance test are shown in table 1.
Table 1 results of test for coating properties of the powder coating of examples and comparative examples
As can be seen from Table 1, the products of examples 1-4 of the invention have good comprehensive properties, the cured coating film is smooth and flat, the gloss and the impact resistance can meet the application requirements, the hardness and the thermal transfer printing effect are obviously improved compared with those of common commercial products, the pencil hardness is 2H, the transfer printing effect is clear, and the paper is not sticky.
The commercial 60/40 polyester resin adopted in the comparative example 1 has poor curing effect after 160 ℃/12min curing due to low carboxyl end activity, and the appearance, impact resistance, gloss and the like of the cured coating film do not meet the requirements;
comparative example 2 the curing condition of comparative example 1 was adjusted to 180 c/15 min, and the appearance of the coating film and impact property were good after sufficient curing was achieved for a long time at high temperature, but the hardness and thermal transfer effect were slightly inferior to those of the product of the present invention.
In conclusion, the method can effectively utilize the papermaking byproduct sodium lignin sulfonate, and provides a method for the subsequent comprehensive utilization and development of the papermaking byproduct.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. A preparation method of polyester resin for powder coating mainly comprises the following raw materials in parts by mole:
wherein, besides the raw materials, a catalyst and an antioxidant are added in the preparation process of the polyester resin;
the preparation method comprises the following steps:
(1) Adding 20-30 mol parts of sodium lignin sulfonate into a first reaction container, adding a proper amount of water, stirring, heating to dissolve completely, and then regulating the pH of the solution to 3-4 for full acidification reaction;
(2) Monitoring the pH value of the solution, stopping the acidification reaction when the pH value is still between 3 and 4, then performing reduced pressure distillation to remove water and excessive hydrochloric acid, controlling the vacuum degree to be between-0.095 and-0.098 MPa, sampling and monitoring the content of sodium chloride in the solution, stopping distillation when the mass fraction of the sodium chloride in the solution reaches 18-21%, and performing filter pressing to separate solid lignin sulfonic acid from the solution to obtain solid lignin sulfonic acid for standby;
(3) Adding lignin sulfonic acid obtained in the step (2), 15-25 mol parts of neopentyl glycol, 5-12 mol parts of diethylene glycol, 10-15 mol parts of terephthalic acid and a catalyst accounting for 0.1-0.15% of the total mass of the raw materials into a second reaction container, heating to 185-190 ℃ and preserving heat for a period of time to perform esterification reaction;
(4) When the acid value of the system polymer reaches 50-65mgKOH/g, 8-15 mol parts of bisphenol A diglycidyl ether and 3-6 mol parts of trimethylolpropane are added, then the temperature is raised to 220-225 ℃, and the reaction is carried out for a period of time;
(5) When the acid value of the polymer in the system is reduced to 25-35mgKOH/g, adding an antioxidant with the dosage of 0.2-0.5% of the total mass of the raw materials, and starting a vacuum system to carry out vacuum polycondensation reaction;
(6) When the acid value of the system polymer is reduced to 12-18mgKOH/g, releasing vacuum, adding 10-17 mol parts of 1, 4-butanedisulfonic acid as a polyester end capping agent, and continuing to carry out heat preservation end capping reaction at 220-225 ℃;
(7) Stopping the reaction when the acid value of the polymer in the system reaches 48-54mgKOH/g, discharging, cooling, crushing and granulating to obtain the polyester resin;
the acid value of the obtained polyester resin was 48 to 54mgKOH/g.
2. The process for producing a polyester resin for powder coating according to claim 1, wherein in the step (1), the temperature is raised to 80 to 85 ℃.
3. The process for producing a polyester resin for powder coating according to claim 1, wherein in the step (1), the acidification reaction time is 2 to 3 hours.
4. The process for producing a polyester resin for powder coating according to claim 1, wherein in the step (3), the temperature is raised to 185 to 190 ℃ at a temperature-raising rate of 25 to 30 ℃/h; in the step (4), the temperature is raised to 220-225 ℃ at a temperature raising rate of 6-8 ℃/h.
5. The process for producing a polyester resin for powder coating according to any one of claims 1 to 4, wherein the catalyst is monobutyl tin oxide and the amount of the catalyst is 0.1 to 0.15% of the total mass of the above raw materials; the antioxidant is antioxidant 1010, and the dosage of the antioxidant is 0.2-0.5% of the total mass of the raw materials.
6. The process for producing a polyester resin for powder coating according to any one of claims 1 to 4, wherein the sodium lignin sulfonate is a paper-making byproduct.
7. A polyester resin for powder coating, which is produced by the process for producing a polyester resin according to any one of claims 1 to 5, wherein the polyester resin has an acid value of 48 to 54mgKOH/g.
8. The polyester resin according to claim 7, wherein the softening point of the polyester resin is 112 to 120 ℃.
9. A powder coating material comprising the polyester resin for powder coating material according to claim 7 or 8.
10. A powder coating prepared from the powder coating of claim 9.
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| USRE32408E (en) * | 1982-09-29 | 1987-04-28 | Masonite Corporation | Lignosulfonate-phenol-formaldehyde resin binder |
| JPH1017656A (en) * | 1996-06-28 | 1998-01-20 | Nippon Ester Co Ltd | Production of polyester resin for powder coating material |
| EP2280036B1 (en) * | 2008-05-21 | 2013-11-13 | Toray Industries, Inc. | Method for producing aliphatic polyester resin, and an aliphatic polyester resin composition |
| CN110156974A (en) * | 2019-05-07 | 2019-08-23 | 安徽美佳新材料股份有限公司 | A kind of Heat Resistant Powder Coatings polyester resin |
| CN111019486B (en) * | 2019-12-26 | 2021-11-30 | 杭州吉成塑粉有限公司 | Inorganic whisker fiber toughened epoxy resin powder anticorrosive paint and preparation method thereof |
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