CN117843949A - Autocatalysis fast-curing polyester resin for coiled material and preparation method and application thereof - Google Patents

Abstract

The invention provides an autocatalytic fast-curing polyester resin for coiled materials, a preparation method and application thereof, and raw materials: polyol: 20-44% wt; aromatic polybasic acid: 38-55% wt; branching agent: 0.1-2% wt; amino raw materials: 2-8%; acidolysis agent: 10-20% wt; esterification catalyst: 0.03-0.15% wt; an antioxidant: 0.3 to 3.0 percent by weight; amidation catalyst: 0.001 to 0.4% wt; compared with the prior art, the invention adopts the polyol and the polybasic acid to prepare the carboxyl-terminated polyester resin after esterification, acidolysis end capping and vacuum polycondensation, and the amino raw material reacts with carboxyl in the carboxyl-terminated polyester resin under the catalysis of the amidation catalyst to prepare the amide group, so that the main chain of the polyester resin contains amide bonds. The lone pair electron of the nitrogen atom in the amide bond can catalyze the mutual reaction of the carboxyl of the polyester resin and the epoxy group of the curing agent, realize self-catalysis and be used in the field of coiled materials.

Description

Autocatalysis fast-curing polyester resin for coiled material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of powder coating and polyester resin, and particularly relates to self-catalyzed fast-curing polyester resin for coiled materials, and a preparation method and application thereof.

Background

The coiled material is a continuously coiled material, has the advantages of convenient transportation, storage and processing, is widely used in national economy and life, and is mainly divided into coiled steel, coiled aluminum and the like. The coil is usually coated with a coating material, which plays a role in decorating and protecting the substrate. Traditional coil coatings are mainly solvent-borne coatings, because solvent-borne coatings have high VOC emissions, and the near zero VOC emissions advantage of powder coatings makes them very suitable for coil coating.

However, since the coil has high requirements on the speed of spraying, curing and drying the coating, the common powder coating is difficult to meet the requirements, and the application of the powder coating on the coil is not very practical at present.

Patent publication No. CN112552495A published in 3/26 of 2021 discloses a low-temperature fast-curing polyester resin and a powder coating for coiled materials prepared from the same, which mainly realize a self-extinction function by introducing amino groups and epoxy groups into the resin, however, carboxyl groups, epoxy groups, amino groups and epoxy groups of the polyester resin react with each other under a high-temperature synthesis environment, so that the invention cannot be implemented or has great control difficulty in theory.

Because of high reactivity, polyester resins for coiled materials generally need to be added with small molecules such as triphenylphosphine, triphenylphosphine bromide and the like in a polyester resin or powder formula to catalyze the crosslinking reaction of carboxyl groups and epoxy groups of a curing agent in the polyester resin, however, the small molecules can cause yellowing of the resin and degradation of weather resistance to a certain extent.

The publication No. CN 111138647A published in 5/12/2020 discloses a modified liquid crystal polyester resin and a preparation method thereof, which is mainly realized by adopting a first monomer of hydroxybenzoic acid, a second monomer of parahydroxynaphthoic acid and polyamide to be copolymerized, however, in the actual experimental synthesis process and theoretical analysis, the polyamide such as PA6 cannot be copolymerized or transesterified in the system.

The patent with publication number CN1803953A published in 7/19 2006 discloses a matched coating for an aluminum alloy substrate, wherein the primary coating adopts liquid epoxy resin and primary amine for reaction, and the generated secondary amine can obviously increase the adhesive force between the coating and the substrate. But does not disclose how to cure quickly.

Publication No. CN115197270A published in 10/18/2022 discloses an autocatalytic functional reaction monomer, an autocatalytic polymerization and autocatalytic depolymerization functional copolymer, a preparation method and application thereof, wherein phosphonate ion groups similar to sulfonate are adopted as active groups of a catalyst in a main structure. The yellowing of the resin and the deterioration of weather resistance are easily caused.

Disclosure of Invention

The invention aims to provide an autocatalytic fast-curing polyester resin for coiled materials and a preparation method thereof, wherein a carboxyl-terminated polyester resin is prepared by adopting polyalcohol and polybasic acid through esterification, acidolysis end capping and vacuum polycondensation, and an amide group is prepared by reacting an amino raw material with carboxyl in the carboxyl-terminated polyester resin under the catalysis of an amidation catalyst, so that the main chain of the polyester resin contains an amide bond. The lone pair electron of the nitrogen atom in the amide bond can catalyze the mutual reaction of the carboxyl of the polyester resin and the epoxy group of the curing agent, realize self-catalysis and be used in the field of coiled materials.

It is a further object of the present invention to provide the use of an autocatalytic fast curing polyester resin for coil applications for preparing coil applications.

The specific technical scheme of the invention is as follows:

the invention provides an autocatalytic fast-curing polyester resin for coiled materials, which comprises the following raw materials in percentage by mass: polyol: 20-44% wt; aromatic polybasic acid: 38-55% wt; branching agent: 0.1-2% wt; amino raw materials: 2-8%; acidolysis agent: 10-20% wt; esterification catalyst: 0.03-0.15% wt; an antioxidant: 0.3 to 3.0 percent by weight; amidation catalyst: 0.001 to 0.4% wt; the sum of the mass percentages of the raw materials is 100 percent.

The polyol adopts one or more of neopentyl glycol (NPG), ethylene Glycol (EG), cyclohexanedimethanol (CHDM) and ethylbutyl propylene glycol (BEPD).

The aromatic polybasic acid adopts one or two of terephthalic acid PTA and isophthalic acid IPA.

The branching agent adopts one or two of trimethylol propane TMP, trimethylol ethane TME or dimethylol propionic acid DMPA, preferably dimethylol propionic acid.

The amino raw material comprises ethylenediamine, propylenediamine, hexamethylenediamine, butylenediamine, pentyenediamine, heptylenediamine, decylenediamine, ethanolamine, propanolamine or butanolamine;

the acidolysis agent adopts one or more of isophthalic acid IPA, adipic acid ADA, 1, 4-cyclohexanedicarboxylic acid CHDA, trimellitic anhydride TMA and fumaric acid FCC;

the esterification catalyst adopts an organotin catalyst or a titanium catalyst tin catalyst, preferably one or more of dibutyl tin oxide, tributyl tin oxide, dihydroxybutyl tin chloride, stannous oxalate, monobutyl tin oxide, tetraisopropyl titanate and tetraisobutyl titanate;

the antioxidant is compounded and used by phosphite antioxidants and hindered phenol antioxidants according to the mass ratio of 1:9-9:1; wherein the phosphite antioxidant is selected from tris [ 2.4-di-tert-butylphenyl ] phosphite (antioxidant 168), bis (2, 4-di-tert-butylphenol) pentaerythritol diphosphite (antioxidant 626); the hindered phenol antioxidant adopts pentaerythritol tetra [ beta- ] (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010) and n-stearyl beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076).

The amidation catalyst comprises nano gold, nano silver, nano copper, nano zinc, phosphorous acid, phosphite ester, ammonium chloride and trifluoro benzene sulfonic acid;

the invention provides a preparation method of autocatalytic fast-curing polyester resin for coiled materials, which comprises the following steps:

1) Adding the polyol and the branching agent in the formula amount into a reaction kettle, heating to 160-180 ℃ and melting;

2) Simultaneously adding the formula amount of aromatic polybasic acid and esterification catalyst into a reaction kettle, heating to 235-255 ℃ in nitrogen atmosphere, maintaining, and sampling and detecting an Acid Value (AV) to 4-10 mgKOH/g after the system is clarified;

3) Then cooling to 215-235 ℃ and adding acidolysis agent into a reaction kettle, heating to 235-250 ℃ and maintaining acidolysis end capping until the acid value of the polyester is 44-55mgKOH/g;

4) Cooling to 230-240 ℃ and polycondensing under-0.1 MPA vacuum condition, wherein the acid value reaches 30-40mgKOH/g, and cooling to 190-210 ℃;

5) Adding an amino raw material and an amidation catalyst, maintaining for 1-2 h, cooling to 180-200 ℃, adding a formula antioxidant, maintaining for 5-30min under small vacuum-0.07 MPA, and discharging.

The processes of steps 1), 2), 3) and 5) require the addition of high purity nitrogen (purity greater than 99.99%, the same applies below) for protection.

In the step 2), the temperature is increased to 235-255 ℃ at the speed of 1-2 ℃/min;

in the step 3), the temperature is reduced to 215-235 ℃ at the speed of 3-5 ℃/min; heating to 235-250 ℃ at a heating rate of 1-2 ℃/min;

the self-catalyzed rapid curing polyester resin for coiled materials has the number average molecular weight of 1800-5000g/mol, the viscosity range of 3000-6000 mPa.s/200 ℃, the glass transition temperature (Tg) of more than or equal to 55 ℃, the acid value of 25-50mgKOH/g and the amino content: 0.05 to 0.3m mol/g resin.

The invention provides an application of autocatalytic fast-curing polyester resin for coiled materials, which is used for preparing a coating for coiled materials.

The polyester resin for the traditional coil powder coating is mainly prepared by adding small molecules such as triphenylphosphine, triphenylphosphine bromide and the like at the end of resin synthesis, however, the small molecules can cause yellowing of the resin and degradation of weather resistance to a certain extent. Compared with the prior art, the invention prepares the carboxyl-terminated polyester resin by adopting the polyol and the polybasic acid through esterification, acidolysis end capping and vacuum polycondensation, and prepares the amide group by the reaction of the amino raw material and carboxyl in the carboxyl-terminated polyester resin under the catalysis of the amidation catalyst, thereby realizing the main chain of the polyester resin containing amide bonds. The lone pair electron of the nitrogen atom in the amide bond can catalyze the mutual reaction of the carboxyl of the polyester resin and the epoxy group of the curing agent, realize self-catalysis and be used in the field of coiled materials.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The test materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.

Those of skill in the art, without any particular mention of the techniques or conditions, may follow the techniques or conditions described in the literature in this field or follow the product specifications.

Comparative example 1-comparative example 4

A polyester resin comprising the following raw materials in the amounts shown in table 1.

Example 1-example 2

An autocatalytic fast curing polyester resin for coiled material comprising the following amounts of raw materials as shown in table 1.

Table 1 raw material formulation of polyester resin, actual parameters during synthesis and parameters of finished resin for each of examples and comparative examples

The polyester resin used in comparative example polyester resin A1 was prepared by:

1) Adding the polyol and the branching agent in the formula amount into a reaction kettle, heating to 170 ℃ and melting; 2) Simultaneously adding the formula amount of aromatic polybasic acid and an esterification catalyst into a reaction kettle, heating to 248 ℃ at a speed of 1-2 ℃/min in a nitrogen atmosphere, maintaining, and sampling and detecting an Acid Value (AV) to reach the primary acid value in table 1 after the system is clarified; 3) Then cooling to 220 ℃ at a speed of 3-5 ℃/min, adding an acidolysis agent into a reaction kettle, heating to 244 ℃ at a heating speed of 1-2 ℃/min, and maintaining acidolysis end capping until the acid value of the polyester is the secondary acid value in the acid value table 1; 4) Cooling to 230 ℃ and polycondensing under-0.1 mPa vacuum condition, cooling to 190 ℃ after the acid value reaches the vacuum in table 1, adding formula antioxidant, maintaining the small vacuum of about-0.07 mPa for 5-30min, and discharging. The synthetic stages 1), 2) and 3) require the addition of technical high purity nitrogen for protection.

The polyester resin used in comparative example polyester resin A2 was prepared by:

1) Mixing the formulated amounts of polyol, branching agent andamino starting materialPutting the mixture into a reaction kettle, heating to 170 ℃ and melting; 2) The formula amount of aromatic polybasic acid, esterification catalystAmidation catalystSimultaneously putting the mixture into a reaction kettle, heating to 248 ℃ at a speed of 1-2 ℃/min in nitrogen atmosphere, and maintaining the mixture, and sampling and detecting an Acid Value (AV) to reach the primary acid value in table 1 after the system is clarified; 3) Then cooling to 220 ℃ at a speed of 3-5 ℃/min, adding an acidolysis agent into a reaction kettle, heating to 244 ℃ at a heating speed of 1-2 ℃/min, and maintaining acidolysis end capping until the acid value of the polyester is the secondary acid value in the acid value table 1; 4) Cooling to 230 ℃ and polycondensing under-0.1 mPa vacuum condition, cooling the acid value to 190 ℃ after the acid value reaches the vacuum in table 1, adding the formula antioxidant, maintaining the small vacuum for about-0.07 mPa for 30min, and discharging. The synthetic stages 1), 2) and 3) require the addition of technical high purity nitrogen for protection.

The polyester resin used in comparative example polyester resin A3 was prepared by:

1) Adding the polyol and the branching agent in the formula amount into a reaction kettle, heating to 170 ℃ and melting; 2) The formula amount of aromatic polybasic acid and esterification catalyst are simultaneously put into a reaction kettle, and the mixture is subjected to nitrogen atmosphereRaising the temperature to 248 ℃ at the speed of 1-2 ℃/min and maintaining, and sampling and detecting the Acid Value (AV) to reach the primary acid value in the table 1 after the system is clarified; 3) Then cooling to 220 ℃ at a speed of 3-5 ℃/min and adding an acidolysis agent,Amino starting materials and amidation catalystsPutting the polyester into a reaction kettle, heating to 244 ℃ at a heating rate of 1-2 ℃/min, and maintaining acidolysis end capping until the acid value of the polyester is the secondary acid value in the table 1; 4) Cooling to 230 ℃ and polycondensing under-0.1 mPa vacuum condition, cooling to 190 ℃ after the acid value reaches the vacuum in table 1, adding formula antioxidant, maintaining the small vacuum of about-0.07 mPa for 5-30min, and discharging. The synthetic stages 1), 2) and 3) require the addition of technical high purity nitrogen for protection.

The following comparative polyester resins A4, B1 and B2 were prepared by the following methods:

1) Adding the polyol and the branching agent in the formula amount into a reaction kettle, heating to 170 ℃ and melting; 2) Simultaneously adding the formula amount of aromatic polybasic acid and an esterification catalyst into a reaction kettle, heating to 248 ℃ at a speed of 1-2 ℃/min in a nitrogen atmosphere, maintaining, and sampling and detecting an Acid Value (AV) to reach the primary acid value in table 1 after the system is clarified; 3) Then cooling to 220 ℃ at a speed of 3-5 ℃/min, adding an acidolysis agent into a reaction kettle, heating to 244 ℃ at a heating speed of 1-2 ℃/min, and maintaining acidolysis end capping until the acid value of the polyester is the secondary acid value in the acid value table 1; 4) Cooling to 230 ℃ and polycondensing under-0.1 mPa vacuum condition, wherein the acid value is cooled to 210 ℃ after reaching the vacuum in the table 1; 5) Adding an amino raw material and an amidation catalyst, cooling to 190 ℃ after maintaining for 1.5h, adding a formula amount of antioxidant, and discharging after maintaining for 5-30min under small vacuum of about-0.07 mPa. The synthetic stages 1), 2), 3) and 5) require the addition of technical high purity nitrogen for protection.

Wherein comparative example A1 is a system free of amino-containing starting materials and amidation catalysts; the formulation of comparative examples A2 and A3 is the same as example B1, wherein the comparative example A2 is added with the amino starting material and the amidation catalyst in a single esterification stage, and the comparative example A3 is added with the amino starting material and the amidation catalyst in an acidolysis end-capping stage; comparative examples A4, B1 and B2 were synthesized according to the method of the present invention,only comparative example A4 has less amino raw material consumption。

From the above table, it can be seen that the color of the comparative examples A2 and A3 is poor, and theoretical analysis considers that the thermal oxidation of the amino raw material at high temperature for a long time causes the side reaction of the amino group to generate various chromophore groups (the measured amino content is lower than that of the example B1), so that the polyester resin is poor in color and cannot meet the market demand, and therefore the performance of the powder coating is not detected later. The colors of comparative example A4, examples B1 and B2 are pale white to pale yellow particles, which meet the market demand, and the powder coating properties will be measured normally later.

Powder coatings were prepared using the above prepared examples, comparative examples A1 and A4 polyester resins, curing agents, leveling agents, pigments, inorganic fillers, auxiliaries, and the like, and the specific formulations are shown in table 2 below.

Table 2 powder coating formulations for each of the examples and comparative examples

The preparation method of the powder coating of each example and the comparative example comprises the following steps: weighing different raw materials according to the formula in Table 2, fully premixing in a mixing tank, co-extruding through an extruder, tabletting, crushing, grinding, sieving and packaging to obtain the self-catalyzed powder coating for the coiled material. The powder coating was then sprayed onto the surface of a conventional iron plate produced by tagda by means of electrostatic spraying, and the coating was baked at 200 c @10min and 270 c @60s to retest the properties, the results being shown in table 3.

TABLE 3 Properties of the coatings

Remarks: leveling grades PCI from 1 to 10 represent improvements in leveling performance, where PCI-10 represents the same leveling performance as mirror, and currently commercially available standard boards are used to evaluate the PCI grade.

The above underlined is not satisfactory for the present invention.

Gel time refers to the time required for a volume of powder coating to become non-deformable after melting under specified conditions, wherein a shorter gel time indicates a faster internal reaction of the powder coating and a shorter time required for complete curing into a coating film. It can be seen from table 3 that the conventional powder of polyester resin (formula a 1) has a long gel time (750 s), and the gel time shows a significantly decreasing trend with increasing amino content in the polyester resin, showing that the internal reaction of the powder coating is faster and faster, and shows a self-catalyzing effect. The coatings of example resins B1 and B2 prepared in table 3 using examples 1 and 2 of the present invention have short gel times (gel times of formula B1 and formula B2 are 32s and 28s, respectively), have good autocatalytic rapid curing effect, and meet the requirement of rapid curing of polyester resins for coil (270 ℃ C. @60 s). Comparative example A1, which shows that the powder coating cannot be cured, is impact-dropped under coil steel curing conditions (270 ℃ c.@ 60 s); formulation a4 is a comparative example using a smaller amount of amino raw material, and its (270 ℃ C.@ 60 s) coating has an impact performance satisfying the positive recoil 50/20kg.cmf lower than that of the coatings of example resin B1 and example resin B2, and the coating has an impact performance satisfying the positive recoil 50/50kg.cmf under the coil curing condition (270 ℃ C.@ 60 s), further proving that the self-catalyzed polyester resin powder coating of the present invention satisfies the special requirements of the coil.

The self-catalyzed polyester resin for coil steel is prepared by adopting polyalcohol and polybasic acid to prepare carboxyl-terminated polyester resin after esterification, acidolysis end capping and vacuum polycondensation, and an amino raw material reacts with carboxyl in the carboxyl-terminated polyester resin under the catalysis of an amidation catalyst to prepare an amide group, so that the main chain of the polyester resin contains amide bonds. The lone pair electron of the nitrogen atom in the amide bond can catalyze the mutual reaction of the carboxyl of the polyester resin and the epoxy group of the curing agent, realize self-catalysis and be used in the field of coiled materials.

The above embodiments are described in order to facilitate the understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.

Claims (10)

1. The self-catalyzed fast-curing polyester resin for coiled materials is characterized by comprising the following raw materials in percentage by mass: polyol: 20-44% wt; aromatic polybasic acid: 38-55% wt; branching agent: 0.1-2% wt; amino raw materials: 2-8%; acidolysis agent: 10-20% wt; esterification catalyst: 0.03-0.15% wt; an antioxidant: 0.3 to 3.0 percent by weight; amidation catalyst: 0.001 to 0.4% wt; the sum of the mass percentages of the raw materials is 100 percent.

2. The autocatalytic fast curing polyester resin for coil of claim 1, wherein the polyol is a composition of one or more of neopentyl glycol (NPG), ethylene Glycol (EG), cyclohexanedimethanol (CHDM), ethylbutyl propylene glycol (BEPD).

3. The autocatalytic fast curing polyester resin for coil stock according to claim 1, wherein the aromatic polybasic acid is one or both of terephthalic acid PTA and isophthalic acid IPA.

4. The autocatalytic fast curing polyester resin for rolls according to claim 1, wherein the branching agent is one or a mixture of two of trimethylolpropane TMP, trimethylolethane TME, or dimethylolpropionic acid DMPA.

5. The autocatalytic fast curing polyester resin for coil stock according to claim 1, wherein the amino raw material comprises ethylenediamine, propylenediamine, hexylenediamine, butylenediamine, pentylenediamine, heptylenediamine, decylenediamine, ethanolamine, propanolamine or butanolamine.

6. The autocatalytic fast curing polyester resin for coiled material according to claim 1, wherein the acidolysis agent is one or a mixture of more of isophthalic acid IPA, adipic acid ADA, 1, 4-cyclohexanedicarboxylic acid CHDA, trimellitic anhydride TMA and fumaric acid FCC.

7. The self-catalyzed fast curing polyester resin for rolls according to claim 1, wherein the esterification catalyst is an organotin-based or titanium-based catalyst tin-based catalyst.

8. The autocatalytic fast curing polyester resin for coil of claim 1, wherein the amidation catalyst comprises nano gold, nano silver, nano copper, nano zinc, phosphorous acid, phosphite, ammonium chloride, trifluoro benzene sulfonic acid.

9. A process for the preparation of an autocatalytic fast curing polyester resin for a web as claimed in any one of claims 1 to 8, said process comprising the steps of:

1) Adding the polyol and the branching agent in the formula amount into a reaction kettle, heating to 160-180 ℃ and melting;

2) Simultaneously adding the formula amount of aromatic polybasic acid and esterification catalyst into a reaction kettle, heating to 235-255 ℃ in nitrogen atmosphere, maintaining, and sampling and detecting an Acid Value (AV) to 4-10 mgKOH/g after the system is clarified;

3) Then cooling to 215-235 ℃ and adding acidolysis agent into a reaction kettle, heating to 235-250 ℃ and maintaining acidolysis end capping until the acid value of the polyester is 44-55mgKOH/g;

4) Cooling to 230-240 ℃ and polycondensing under-0.1 MPA vacuum condition, wherein the acid value reaches 30-40mgKOH/g, and cooling to 190-210 ℃;

5) Adding an amino raw material and an amidation catalyst, maintaining for 1-2 h, cooling to 180-200 ℃, adding a formula antioxidant, maintaining for 5-30min under small vacuum-0.07 MPA, and discharging.

10. Use of the autocatalytic fast curing polyester resin for coil use according to claim 9 for preparing a coating for coil use.