Disclosure of Invention
Aiming at the technical problems at present, the invention provides hydrolysis-resistant polyester resin for water-based coil primer paint and a preparation method thereof, the hydrolysis-resistant polyester resin for the water-based coil primer paint is synthesized, and the problems of unstable storage, poor weather resistance, low curing efficiency and the like of the water-based polyester resin are solved.
An anti-hydrolysis polyester resin for water-based coil primer coating, the molecular weight of the polyester resin is 1000-20000, the acid value is 20-100mgKOH/g, the hydroxyl value is 50-300mgKOH/g, the solid content is 40-80%, and the neutralization degree is 50-100%;
the polyester resin comprises the following raw materials in percentage by mass: 10-40 wt% of polyhydric alcohol, 10-40 wt% of polybasic acid, 2-15 wt% of hydrolysis-resistant monomer, 0.01-1 wt% of catalyst, 1-5 wt% of neutralizing agent, 10-30 wt% of hydrophilic solvent, 1-5 wt% of water-based monomer and the balance of deionized water;
the hydrolysis-resistant monomer is synthesized by dibasic acid and epoxy substances: mixing the dibasic acid with the epoxy substance and other substances, heating to 130-140 ℃, and reacting for 5-6h to obtain the hydrolysis-resistant monomer;
the polyol is a diol.
Preferably, the specific synthesis method of the hydrolysis-resistant monomer is as follows: mixing the dibasic acid with the epoxy substances and the like, heating to 130 ℃, and reacting for 5 hours to obtain the hydrolysis-resistant monomer.
More preferably, the dibasic acid is one of isophthalic acid, phthalic acid, terephthalic acid, succinic acid and glutaric acid, and the epoxy substance is one of ethylene oxide, propylene oxide, ethylene glycol glycidyl ether, propylene glycol glycidyl ether, diethylene glycol glycidyl ether, dipropylene glycol glycidyl ether and epoxy resin.
Preferably, the catalyst is one of antimony series and organic tin series catalysts, and the dosage of the catalyst is 0.01 to 1 weight percent of the total mass of the polymer; the polybasic acid is one or two of dibasic acid and anhydride mixed at any ratio.
Further preferably, the polyacid is selected from: isophthalic acid, phthalic acid, terephthalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, maleic acid, tetrahydrophthalic acid, hexahydroisophthalic acid, 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid or a plurality of the above in any proportion.
Preferably, the water-based monomer is one or more of phthalic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride and maleic anhydride in any proportion.
Preferably, the hydrophilic solvent is one or more selected from ethylene glycol monobutyl ether, propylene glycol methyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, diethylene glycol butyl ether, ethylene glycol methyl ether acetate, ethanol, n-butanol, isopropanol and butanol; the neutralizer is selected from one of ammonia, N, N dimethylethanolamine, diethanolamine, triethanolamine, triethylamine and 1-methyldiethanolamine;
the invention selects polyhydric alcohol with excellent hydrolysis resistance, polybasic acid monomer and hydrolysis resistance monomer to obtain high molecular polymer with medium and low molecular weight through polycondensation reaction under the condition of catalyst, then the material reacts with water-based monomer, and finally neutralization is completed, and water is added to obtain the water-based polyester resin product.
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer paint comprises the following preparation steps in sequence:
1) putting polyalcohol, polybasic acid and hydrolysis-resistant monomer into a reactor, slowly heating to 120 ℃, putting a catalyst into the reactor, slowly heating to 150 ℃, and keeping the temperature for 1-1.5 h;
2) continuously heating up to 10 ℃ per hour until the temperature reaches 220 ℃, and carrying out heat preservation reaction;
3) observing the reaction water yield, starting to measure the acid value at 88-93% of the water yield, and cooling to 150-;
4) adding a water-based monomer, reacting for 0.5-1h, measuring the acid value to be less than 50mgKOH/g, and cooling to 60 ℃;
5) adding a hydrophilic solvent, a neutralizer and deionized water at 60 ℃, and fully and uniformly stirring to obtain the polyester resin.
The polyester resin synthesized by the invention introduces the hydrolysis-resistant monomer, the hydrolysis-resistant monomer is blocked on the main chain of the polyester molecule, the hydrolysis-resistant monomer has a larger hydrophobic group, is in an umbrella cap state, protects an ester bond from hydrolysis, is not abnormal when stored in a thermostat of 50 ℃ for 6 months, has uniform molecular weight distribution, is matched with the amino resin to obtain a paint film with T bending of 2T, 340 ultraviolet aging of within 10 percent of light loss rate after 1500h, has excellent impact resistance of 90cm, is high in paint film fullness, and has good gloss and color retention.
The polyester resin prepared by the invention has active crosslinking sites such as hydroxyl, carboxyl and the like, and can be subjected to curing reaction with amino resin at high temperature (the plate temperature is 180-240 ℃), so that the polyester resin is used for preparing coiled material polyester primer coating with low VOC content and used for various metal coiled materials, and the baking temperature can be obviously reduced by matching with a catalyst (the existing catalyst), and the film forming effect is excellent.
The hydrolysis-resistant monomer is introduced, is segmented on a polyester molecular main chain, has a large hydrophobic group, is in an umbrella cap state, protects ester bonds from hydrolysis, successfully improves the hydrolysis stability of the water-based polyester, can meet the performance requirement of the water-based paint for the coil, and is used as the polyester resin for the primer paint for the water-based coil, so that the use amount of a solvent in the paint is effectively reduced, the VOC emission is reduced, and the polyester resin is safe and environment-friendly; the polyester resin of the present invention has the advantages of storage stability, excellent weather resistance and high curing efficiency.
Detailed Description
The present invention will be described in further detail with reference to the following examples, but it should not be construed that the scope of the present invention is limited to the examples. The techniques realized based on the above contents of the present invention all belong to the scope of the present invention, and the following embodiments are all completed by using the conventional prior art except for the specific description.
Example 1
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer coating comprises the following steps:
and (3) synthesis of hydrolysis-resistant monomer V-2: mixing isophthalic acid, glycol glycidyl ether and other substances, heating to 130 ℃, reacting for 5 hours to obtain hydrolysis-resistant monomer V-2, and filtering for later use;
adding 110g of neopentyl glycol, 35g of methyl propylene glycol, 50g of V-2 monomer, 60g of adipic acid, 200g of isophthalic acid and 25g of 1, 4-cyclohexanedicarboxylic acid into a four-neck flask provided with a thermometer, a stirring device and a condensation water separation device, heating to slowly raise the temperature to completely melt the solid materials, stirring, adding 0.3g of tin oxide serving as a catalyst under the condition of melting of materials at 120 ℃, adjusting the temperature of the materials to 150 ℃ within 2 hours, carrying out heat preservation reaction for 1 hour, controlling the temperature rise rate to be 10 ℃/h, gradually raising the temperature to 220 ℃, carrying out heat preservation reaction at the temperature, continuously observing the water yield in the reaction process, when the water yield reaches 90 percent of theoretical water yield, starting to measure the acid value, when the theoretical acid value is less than 5mgKOH/g, cooling the material to 160 ℃, adding 30g of trimellitic anhydride, reacting for 0.5h, and cooling to 60 ℃ after measuring the acid value is less than 50 mgKOH/g;
dilution stage
Cooling the reaction to 60 ℃, adding 25g of neutralizer N, N dimethyl ethanolamine, stirring for reaction for 0.5 hour, adding 200g of hydrophilic solvent ethylene glycol monobutyl ether, adding 234g of deionized water, and adjusting until the solid content of the product is 50 wt%, thereby obtaining hydrolysis-resistant polyester resin for the water-based coil coating primer, wherein the molecular weight is 5400, the acid value is 45mgKOH/g, and the viscosity is 1500 mPa.s;
after hydrolysis-resistant monomer V-2 is introduced into the polyester resin, the polyester resin is stored in a thermostat at 50 ℃ for 6 months without abnormity, and the resin without the hydrolysis-resistant monomer is stored in the thermostat at 50 ℃ for 10-15 days to generate turbidity and delamination.
Example 2
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer paint comprises the following steps:
and (3) synthesis of hydrolysis-resistant monomer V-2: mixing terephthalic acid with ethylene glycol glycidyl ether and other substances, heating to 130 ℃, reacting for 5 hours to obtain hydrolysis-resistant monomer V-2, and filtering for later use;
adding 99g of neopentyl glycol, 16g of cyclohexanedimethanol, 35g of 2-methyl glycol, 58g of V-2 monomer, 75g of adipic acid, 140g of terephthalic acid and 25g of 1, 4-cyclohexanedicarboxylic acid into a four-neck flask provided with a thermometer, a stirring device and a condensation water separation device, heating to slowly raise the temperature to completely melt the solid materials, and stirring; adding 0.5g of catalyst monobutyl tin oxide under the condition of melting a material at 120 ℃, adjusting the temperature of the material to 150 ℃ within 2 hours, carrying out heat preservation reaction for 1 hour, controlling the heating rate to be 10 ℃/hour, gradually heating to 220 ℃, carrying out heat preservation reaction at the temperature, continuously observing the water yield in the reaction process, starting to measure the acid value when the water yield reaches 88 percent of theoretical water yield, when the theoretical acid value is less than 5mgKOH/g, cooling the material to 160 ℃, adding 25g of trimellitic anhydride, carrying out reaction for 0.5 hour, and cooling to 60 ℃ after the measured acid value is less than 50 mgKOH/g;
dilution stage
Cooling the reaction to 60 ℃, adding 25g of neutralizer N, N-dimethylethanolamine, stirring for reacting for 0.5 hour, adding 150g of hydrophilic solvent ethylene glycol monobutyl ether, adding 250g of deionized water, and adjusting until the solid content of the product is 50 wt%, thereby obtaining hydrolysis-resistant polyester resin for the water-based coil coating primer, wherein the molecular weight of the polyester resin is 3200, the acid value of the polyester resin is 40mgKOH/g, and the viscosity of the polyester resin is 2300 mPa.s;
after the hydrolysis-resistant monomer V-2 is introduced into the polyester resin, the polyester resin is stored in a 50 ℃ thermostat for 6 months without abnormity, and the resin without the hydrolysis-resistant monomer is stored in the 50 ℃ thermostat for 10-15 days to cause the phenomena of turbidity and delamination.
Example 3
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer coating comprises the following steps:
and (3) synthesis of hydrolysis-resistant monomer V-2: mixing phthalic acid with ethylene glycol glycidyl ether and other substances, heating to 130 ℃, reacting for 5 hours to obtain hydrolysis-resistant monomer V-2, and filtering for later use;
adding 98g of propylene glycol, 10g of methyl propylene glycol, 40g of 1, 3-butanediol, 35g of V-2 monomer, 75g of adipic acid, 150g of terephthalic acid and 23g of 1, 2-cyclohexanedicarboxylic acid into a four-neck flask provided with a thermometer, a stirring device and a condensation and water separation device, heating slowly to melt all solid materials, and stirring; adding 0.5g of esterification catalyst 4100 under the condition of melting a material at 120 ℃, adjusting the temperature of the material to 160 ℃ within 2 hours, carrying out heat preservation reaction for 1 hour, controlling the heating rate to be 10 ℃/hour, gradually heating to 220 ℃, carrying out heat preservation reaction at the temperature, continuously observing the water yield in the reaction process, starting to measure the acid value when the water yield reaches 93 percent of the theoretical water yield, when the theoretical acid value is less than 5mgKOH/g, cooling the material to 155 ℃, adding 25g of trimellitic anhydride, carrying out reaction for 0.5 hour, and cooling to 60 ℃ after the measured acid value is less than 50 mgKOH/g;
dilution stage
And (3) cooling the reaction to 60 ℃, adding 25g of triethylamine as a neutralizing agent, stirring for reaction for 0.5 hour, adding 180g of propylene glycol methyl ether as a hydrophilic solvent, adding 187g of deionized water, and adjusting until the solid content of the product is 50 wt%, thereby obtaining the hydrolysis-resistant polyester resin for the water-based coil coating primer, which has the molecular weight of 4400, the acid value of 50mgKOH/g and the viscosity of 4500 mPa.s.
After the hydrolysis-resistant monomer V-2 is introduced into the polyester resin, the polyester resin is stored in a 50 ℃ thermostat for 6 months without abnormity, and the resin without the hydrolysis-resistant monomer is stored in the 50 ℃ thermostat for 10-15 days to cause the phenomena of turbidity and delamination.
Example 4
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer paint comprises the following steps:
and (3) synthesis of hydrolysis-resistant monomer V-2: mixing phthalic anhydride with ethylene glycol glycidyl ether and other substances, heating to 130 ℃, reacting for 5 hours to obtain an anti-hydrolysis monomer V-2, and filtering for later use;
85g of neopentyl glycol, 5g of cyclohexanedimethanol, 43g of hexanediol, 45g of V-2 monomer, 70g of adipic acid, 150g of isophthalic acid and 23g of 1, 2-cyclohexanedicarboxylic acid are added into a four-neck flask provided with a thermometer, a stirring device and a condensation water separation device, the temperature is slowly increased by heating, the solid materials are completely melted, and stirring is started. Adding 0.4g of esterification catalyst 4100 under the condition of melting a material at 120 ℃, adjusting the temperature of the material to 160 ℃ within 2h, carrying out heat preservation reaction for 1h, controlling the heating rate to be 10 ℃/h, gradually heating to 220 ℃, carrying out heat preservation reaction at the temperature, continuously observing the water yield in the reaction process, starting to measure the acid value when the water yield reaches 90 percent of theoretical water yield, when the theoretical acid value is less than 5mgKOH/g, cooling the material to 155 ℃, adding 30g of trimellitic anhydride, carrying out reaction for 0.5h, and cooling to 60 ℃ after the measured acid value is less than 50 mgKOH/g;
dilution stage
And (3) cooling to 60 ℃ for reaction, adding 25g of triethylamine as a neutralizing agent, stirring for reaction for 0.5 hour, adding 200g of hydrophilic propylene glycol methyl ether, and adding deionized water to adjust the solid content of the product to 50 wt%, thereby obtaining the hydrolysis-resistant polyester resin for the water-based coil coating primer, which has the molecular weight of 6500, the acid value of 60mgKOH/g and the viscosity of 5200 mPa.s.
After the hydrolysis-resistant monomer V-2 is introduced into the polyester resin, the polyester resin is stored in a 50 ℃ thermostat for 6 months without abnormity, and the resin without the hydrolysis-resistant monomer is stored in the 50 ℃ thermostat for 10-15 days to cause the phenomena of turbidity and delamination.
Example 5
A preparation method of hydrolysis-resistant polyester resin for water-based coil primer paint comprises the following steps:
and (3) synthesis of hydrolysis-resistant monomer V-2: mixing phthalic anhydride and diethylene glycol glycidyl ether and other substances, heating to 130 ℃, reacting for 5 hours to obtain an anti-hydrolysis monomer V-2, and filtering for later use.
Adding 85g of methyl propylene glycol, 20g of 2-methyl-3-propylene glycol, 35g of hexanediol, 45g of V-2 monomer, 75g of adipic acid, 140g of phthalic anhydride and 22g of suberic acid into a four-neck flask with a thermometer, a stirring device and a condensation water separation device, heating slowly to melt all solid materials, and stirring; adding 0.3g of esterification catalyst 4100 under the condition of melting materials at the temperature of 80 ℃, adjusting the temperature of the materials to 150 ℃ within 2 hours, carrying out heat preservation reaction for 1 hour, controlling the heating rate to be 10 ℃/hour, gradually heating to 220 ℃, carrying out heat preservation reaction at the temperature, continuously observing the water yield in the reaction process, starting to measure the acid value when the water yield reaches the theoretical water yield, when the theoretical acid value is less than 5mgKOH/g, cooling the materials to 160 ℃, adding 30g of trimellitic anhydride, carrying out reaction for 0.5 hour, and cooling to 60 ℃ after the measured acid value is less than 50 mgKOH/g;
dilution stage
And (3) cooling to 60 ℃, adding 26g of diethanolamine serving as a neutralizing agent, stirring for reacting for 0.5 hour, adding 200g of hydrophilic propylene glycol methyl ether, and adding deionized water to adjust the solid content of the product to 50 wt%, thereby obtaining the hydrolysis-resistant polyester resin for the water-based coil coating primer, which has the molecular weight of 1200, the acid value of 35mgKOH/g and the viscosity of 2600 mPa.s.
After hydrolysis-resistant monomer V-2 is introduced into the polyester resin, the polyester resin is stored in a thermostat at 50 ℃ for 6 months without abnormity, and the resin without the hydrolysis-resistant monomer is stored in the thermostat at 50 ℃ for 10-15 days to generate turbidity and delamination.
Test of
The resin in example 1 is selected, the water-based coil coating primer is prepared according to the following formula, and the performance evaluation result is as follows:
TABLE 1 Water-borne coil coating primer formulation
Name of raw materials
|
Proportioning,%
|
Hydrolysis resistant polyester resins
|
35
|
Ethylene glycol monobutyl ether
|
5
|
NN dimethylethanolamine
|
0.8
|
Defoaming agent 810
|
0.2
|
Leveling agent 450
|
0.1
|
Substrate wetting agent 4100
|
0.1
|
Titanium white powder
|
10
|
Carbon black
|
1
|
Precipitated barium sulfate
|
20
|
Deionized water
|
27.8
|
In total
|
100 |
TABLE 2 detection results of the performance of water-based coil coating primers
Item
|
Index requirement
|
The result of the detection
|
State in the container
|
Even without hard blocks after stirring
|
Uniformly stirred without hard lumps
|
Hardness of pencil
|
-
|
2H
|
Reverse impact/(kg. cm)
|
-
|
50
|
Solvent resistance (MEK) wipe/wipe
|
-
|
150
|
T bend/T
|
-
|
2
|
Cross-cut adhesion/grade
|
-
|
0 |
Note: reference standard HG/T3830-2006 coil coating
By evaluating the performance of the colored paint, the performance of the water-based resin reaches the application standard of the oleoresin and is excellent.