CN112251128A

CN112251128A - Thick plate polyurethane primer and preparation method thereof

Info

Publication number: CN112251128A
Application number: CN202011055503.0A
Authority: CN
Inventors: 于东澳; 黄雨花
Original assignee: Nippon Paint Tianjin Co Ltd
Current assignee: Nippon Paint Tianjin Co Ltd
Priority date: 2016-01-29
Filing date: 2016-01-29
Publication date: 2021-01-22
Also published as: CN105602435A

Abstract

The invention discloses a thick plate polyurethane primer which comprises the following components in parts by weight: 17-35 parts of polyester resin; 2-6 parts of amino resin; 2-6 parts of isocyanate; 1.5-2.9 parts of epoxy resin; 18-25 parts of a pigment; 0.7-6 parts of an auxiliary agent; 8-20 parts of a solvent. The invention also discloses a preparation method of the thick plate polyurethane primer. The thick plate polyurethane primer T bend provided by the invention can reach 0T, has no crack and good flexibility, and avoids paint falling phenomenon in the processing process; the salt spray resistance is high, and the salt spray test can reach level 1 in 1000 hours by matching with the polyester finish paint with general performance; the substrate adhesion and the finish adhesion are superior to the traditional epoxy primer and polyester primer. Compared with the traditional primer, the thick plate polyurethane primer provided by the invention has better adhesive force, flexibility and chemical corrosion resistance.

Description

Thick plate polyurethane primer and preparation method thereof

The application is a divisional application of 2016, 1, 29, application No. 201610068468.3 entitled polyurethane primer for thick plate and its preparation method.

Technical Field

The invention relates to the technical field of coatings, in particular to a thick plate polyurethane primer and a preparation method thereof.

Background

In recent years, the application field of the precoated coiled material in China is continuously expanded, and the precoated coiled material is expanded from the prior building field (such as external walls, indoor decoration and the like) to the household appliance industry (such as refrigerators, microwave ovens and the like) and even the transportation field. The precoated coil is coated well and can be directly subjected to various processing and forming processes, so that the precoated coil is required to have high strength and good machining performance. In addition, when the precoated coiled material is applied to the fields of buildings, household appliances and transportation, the application conditions are harsh, and therefore, the precoated coiled material needs to have good corrosion resistance and physical shielding performance.

For the composite coating of the pre-coated coiled material, the primer is the basis, the performance of the whole coating is influenced to a great extent, and the mechanical properties such as the adhesive force, the corrosion resistance, the T bend, the cupping and the like of the substrate are influenced. Conventional primers are typically applied to the sheet, such as epoxy primers and polyester-amino primers (polyester primers for short). The epoxy primer has good adhesion to a substrate and good chemical corrosion resistance, but has poor flexibility. The polyester primer has good adhesion with a substrate and excellent flexibility, but is sensitive to a humid environment and has lower chemical corrosion resistance than an epoxy primer. If the base material is thicker, the internal stress generated in the processing process, particularly in the bending process, is stronger than that of a thin plate, the surface area change is large, and more severe requirements on the flexibility of the coating and the adhesive force of the substrate are provided for preventing the coating at the bending part from falling off.

In view of the above, there is a need to provide a polyester primer with better T-bend and adhesion effects to meet the requirements of pre-coated coil production and development.

Disclosure of Invention

In order to overcome the defect of poor performance of the primer in the prior art, the invention aims to provide the thick plate polyurethane primer, and the T bend of the primer can achieve the technical effects of no crack at 0T, excellent adhesion and no abnormity in salt spray resistance for 1000 hours.

The invention also aims to provide a preparation method of the thick plate polyurethane primer.

In order to achieve the above object, one aspect of the present invention employs the following technical solutions:

the thick plate polyurethane primer comprises the following components in parts by weight:

the polyurethane primer for the thick plate has the advantages that the ratio of polyester to amino is 2-5, the ratio of polyester to isocyanate is 3-6, the ratio of epoxy resin is 0.08-0.12, and the ratio of pigment is 1.0-1.8.

The molecular weight of the polyester resin is 10000-60000, the hydroxyl value is 4-8 mgKOH/g, and the acid value is 0-13 mgKOH/g; such as SKYBON ES 420 from the SK group of Korea.

The amino resin is a fully methylated melamine resin or a mixture of the fully methylated melamine resin and a part of methylated amino resin or a mixture of the fully methylated melamine resin and a high imino methylated melamine resin; the solid content of the amino resin is more than or equal to 80 percent; for example: cymelan 303, Kanno 717, Shanghai Yuanbang chemical amino resin YP 5603.

The isocyanate is a blocked isocyanate such as DESMODUR 3175SN, DESMODUR RL1265, DESMODUR BL3272 from Bayer, Germany.

The epoxy resin can be HG resin of Jiangsu Hongye company and EPIKOTE 828EL of Dutch shell.

The pigment is an extender pigment or a coloring pigment, and preferably at least one of barium sulfate, titanium dioxide, calcined kaolin, strontium chrome yellow and the like.

The auxiliary agent comprises the following components in parts by weight:

0.2-0.5 part of an acid catalyst;

0.5-2 parts of organic tin catalyst.

The acid catalyst is at least one of p-toluenesulfonic acid and blocked acid thereof, dinonyl naphthalenesulfonic acid and blocked acid thereof; for example, NATURE 1051 available from King, BYK-450 available from Bik Chemicals, Germany, and CATALYST 6000 available from Nanjing, Seisakusho chemical industries.

The organic tin catalyst is a blocked polyurethane catalyst; preferably dibutyltin dilaurate with relatively high cost performance; examples thereof include DY-12 produced by Shanghai Deyin chemical company, and DBTL produced by Shanghai Yutian chemical company.

The auxiliary agent also comprises the following components in parts by weight:

0.1-1 part of anti-settling agent;

0.5-1 part of adhesion promoter;

0.5-1.5 parts of a leveling defoaming agent.

The anti-settling agent is at least one of fumed silica or bentonite, such as XHF and CAB-O-SIL M-5 available from Jinhao nanometer materials.

The adhesion promoter is TZ-8805 of Shanghai Weihai trade company Limited or PAE 206 produced by Yixing Ming chemical industry.

The leveling defoaming agent is an acrylic defoaming agent or a fluorine modified acrylic defoaming agent; such as LEVELER S (EX) from Nippon paint (China) Inc.; EFKA 3600 from BASF ltd (china).

The auxiliary agent further comprises 0.1-1 part of a dispersing agent.

The dispersant is a controlled flocculation wetting dispersant; such as BYK-P104, AT-204, R-5310RESIN from Picker chemical, Germany.

The solvent is at least one of S-100# aromatic solvent or trimethylbenzene solvent, S-150# aromatic solvent or durene solvent, cyclohexanone, isophorone, isobutanol, nylon acid methyl ester (DBE) and ethylene glycol butyl ether.

The invention also provides a preparation method of the thick plate polyurethane primer, which comprises the following steps:

(1) mixing 13-25 parts of polyester resin and 18-25 parts of pigment, adding 4-10 parts of solvent, and grinding to obtain slurry;

(2) adding 4-10 parts of polyester resin, 2-6 parts of isocyanate and 0.5-2 parts of organic tin catalyst into the slurry and mixing; then adding 2-6 parts of amino resin, 0.2-0.5 part of acid catalyst, 1.5-2.9 parts of epoxy resin and 4-10 parts of solvent, mixing and filtering to obtain the thick plate polyurethane primer;

or:

(1) mixing 13-25 parts of polyester resin, 18-25 parts of pigment and 0.1-1 part of anti-settling agent, adding 4-10 parts of solvent, and grinding to obtain slurry;

(2) adding 4-10 parts of polyester resin, 2-6 parts of isocyanate and 0.5-2 parts of organic tin catalyst into the slurry and mixing; then adding 2-6 parts of amino resin, 0.2-0.5 part of acid catalyst, 1.5-2.9 parts of epoxy resin, 0.5-1.5 parts of leveling defoaming agent, 0.5-1.0 part of adhesion promoter and 4-10 parts of solvent, mixing and filtering to obtain the thick plate polyurethane primer;

or:

(1) mixing 13-25 parts of polyester resin, 18-25 parts of pigment, 0.1-1 part of anti-settling agent and 0.1-1 part of dispersing agent, adding 4-10 parts of solvent, and grinding to obtain slurry;

(2) adding 4-10 parts of polyester resin, 2-6 parts of isocyanate and 0.5-2 parts of organic tin catalyst into the slurry and mixing; then, 2-6 parts of amino resin, 0.2-0.5 part of acid catalyst, 1.5-2.9 parts of epoxy resin, 0.5-1.5 parts of leveling defoaming agent, 0.5-1.0 part of adhesion promoter and 4-10 parts of solvent are added, mixed and filtered to obtain the thick plate polyurethane primer.

The minimum film forming temperature of the thick plate polyurethane primer is 200 ℃.

The fineness of the grinding is not more than 15 mu m.

The filtration was performed using a 80 μm filter bag.

The viscosity of the thick plate polyurethane primer is measured at 20 ℃ in a cup of 120-140S/coat-4 # or adjusted to 500-600 mPa.s.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

the thick plate polyurethane primer T bend provided by the invention can reach 0T, has no crack and good flexibility, and avoids paint falling phenomenon in the processing process; the salt spray resistance is high, and the salt spray test can reach level 1 in 1000 hours by matching with the polyester finish paint with general performance; the substrate adhesion and the finish adhesion are superior to the traditional epoxy primer and polyester primer. Compared with the traditional primer, the thick plate polyurethane primer provided by the invention has better adhesive force, flexibility and chemical corrosion resistance.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The use of the auxiliary agent in the present invention helps to accelerate the reaction of the raw materials and maintain the stability of the coating, and the acid catalyst can promote the crosslinking of the amino resin, and is generally a strong acid. When a blocked acid is used, the storage stability of the coating is better.

The terms in the present invention:

the polyester amino ratio in the present invention means a weight ratio of solid parts of the polyester resin to solid parts of the amino resin.

The polyester isocyanate ratio refers to the weight ratio of the solid parts of the polyester resin to the solid parts of the isocyanate.

The epoxy resin ratio refers to the weight ratio of the solid content of the epoxy resin to the solid content of the base material (the base material comprises polyester resin, amino resin, epoxy resin and isocyanate).

The pigment ratio refers to the weight ratio of the pigment (including extender pigment) to the solid parts of the base material (base material including polyester resin, amino resin, epoxy resin and isocyanate).

Example 1

A preparation method of a thick plate polyurethane primer comprises the following steps:

1) mixing polyester resin SKYBON ES 42020 parts, pigment titanium dioxide R-99620 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts and anti-settling agent CAB-O-SIL M-50.2 parts, adding 3 parts of solvent S-100# aromatic solvent and 5 parts of isophorone, and grinding to the fineness of not more than 15 mu M to obtain slurry; the polyester resin is a high molecular weight saturated polyester resin, the molecular weight is 16000, the hydroxyl value is 4-8 mgKOH/g, and the acid value is 0-13 mgKOH/g. The linear or partially branched polyester resin with high molecular weight is adopted, so that the high flexibility, processability and adhesive force of the coating can be ensured. If the hydroxyl value of the polyester resin is too high, the reaction groups can not completely react, so that the water resistance after film formation is influenced; if the hydroxyl value is too low, the reactive group is insufficient, and the processability after film formation is impaired, and the polyester resin can be obtained commercially. The polyester resin and the anti-settling agent are added firstly, and then the pigment is added, so that the viscosity of the system is higher, the polyester resin can fully wet the pigment, and the dispersion effect is exerted.

2) Adding polyester resin SKYBON ES 42010 parts, isocyanate DESMODUR 3175SN 4 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56036 parts of amino resin YP, 60000.4 parts of CATALYST, 828EL 2 parts of epoxy resin EPIKOTE, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic hydrocarbon solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer, wherein the filtering is filtering by using a filter bag of 80 mu m. The minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coat-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the measurement is regulated to 500-600 mPa.s.

The amino resin in this embodiment is a fully methylated melamine resin, which provides faster reaction speed and curing hardness, and in other embodiments, the amino resin for final use may be selected according to the process requirements or the requirements of the user.

The isocyanate in the embodiment is blocked isocyanate, and can ensure the stability, acid resistance and salt spray resistance of the single-component finishing paint over time. The epoxy resin in the embodiment is modified epoxy resin, and the proper amount of the modified epoxy resin can improve the adhesive force and the salt spray resistance of a paint film. Because the compatibility of the auxiliary agent and the base material (polyester resin, amino resin, isocyanate and epoxy resin) is not too good, when the base material is added in a small amount, the base material is turbid, crystals are separated out, and the finish paint effect is influenced. Therefore, in this example, the addition of the binder followed by the addition of the other additives resulted in a more stable coating.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the ratio of polyester to amino groups was 2.5, the ratio of polyester to isocyanate was 4.8, the ratio of epoxy resin was 0.08, and the ratio of pigments was 1.0.

The thick plate polyurethane primer prepared in this example is cured at a metal plate temperature of 224 ± 5 ℃, the thickness of the substrate is 2.5mm, the dry coating thickness of the primer is 10 μm, and the performance of the dry coating thickness is 15 μm when matched with a polyester finish with general performance, as shown in table 1 below.

Example 2

1) mixing and grinding polyester resin SKYBON ES 42017 parts, pigment titanium white R-99619 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 2 parts and isophorone 4 parts until the fineness is not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4208 parts, isocyanate DESMODUR 3175SN 4 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56036 parts of amino resin YP, 60000.4 parts of acid CATALYST CATALYST, 2.9 parts of epoxy resin EPIKOTE 828EL, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the ratio of polyester to amino groups was 2.1, the ratio of polyester to isocyanate was 4.0, the ratio of epoxy resin was 0.12, and the ratio of pigments was 1.0.

Example 3

1) mixing and grinding polyester resin SKYBON ES 42014 parts, pigment titanium dioxide R-99614 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 3 parts and isophorone 5 parts until the fineness is not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4204 parts, isocyanate DESMODUR 3175SN 3 parts and organic tin catalyst DBTL 1 part into the slurry, and mixing; adding 56032 parts of amino resin YP, 60000.4 parts of acid CATALYST CATALYST, 1.6 parts of epoxy resin EPIKOTE 828EL, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the polyester amino ratio was 4.4, the polyester isocyanate ratio was 3.8, the epoxy resin ratio was 0.11, and the pigment ratio was 1.3.

Example 4

1) mixing and grinding polyester resin SKYBON ES 42014 parts, pigment titanium dioxide R-99618 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 2 parts and isophorone 4 parts until the fineness is not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4204 parts, isocyanate DESMODUR 3175SN 4 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56033 parts of amino resin YP, 60000.4 parts of acid CATALYST CATALYST, 1.5 parts of epoxy resin EPIKOTE 828EL, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the polyester amino ratio was 2.8, the polyester isocyanate ratio was 5.4, the epoxy resin ratio was 0.11, and the pigment ratio was 1.6.

The thick plate polyurethane primer prepared in this example is cured at a metal plate temperature of 224 ± 5 ℃, the thickness of the substrate is 2.5mm, the dry coating thickness of the primer is 10 μm, and the performance of the dry coating thickness is 15 μm when matched with a polyester finish with general performance is shown in table 1 below.

Example 5

1) mixing and grinding polyester resin SKYBON ES 42016 parts, pigment titanium dioxide R-99620 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 2 parts and isophorone 4 parts until the fineness is not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4205 parts, isocyanate DESMODUR 3175SN 3 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56033 parts of amino resin YP, 60000.4 parts of CATALYST, 828EL 2 parts of epoxy resin EPIKOTE, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the ratio of polyester to amino groups was 3.5, the ratio of polyester to isocyanate was 5.4, the ratio of epoxy resin was 0.11, and the ratio of pigments was 1.5.

The thick plate polyurethane primer prepared in this example is cured at a metal plate temperature of 224 ± 5 ℃, the thickness of the substrate is 2.5mm, the dry coating thickness of the primer is 10 μm, and the performance of the dry coating thickness is 15 μm when matched with a polyester finish with general performance is shown in table 2 below.

Example 6

1) mixing polyester resin SKYBON ES 42025 parts, pigment titanium dioxide R-99620 parts, barium sulfate PRECIPITATED BARIUM SULFATE 5 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 2 parts and isophorone 4 parts, and grinding to fineness of not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4208 parts, isocyanate DESMODUR 3175SN 6 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56033 parts of amino resin YP, 60000.4 parts of CATALYST, 828EL 2 parts of epoxy resin EPIKOTE, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the ratio of polyester to amino groups was 5.4, the ratio of polyester to isocyanate was 3.5, the ratio of epoxy resin was 0.08, and the ratio of pigments was 1.0.

Example 7

1) mixing polyester resin SKYBON ES 42013 parts, pigment titanium dioxide R-99614 parts, barium sulfate PRECIPITATED BARIUM SULFATE 4 parts, anti-settling agent CAB-O-SIL M-50.2 parts, solvent S-100# aromatic solvent 2 parts and isophorone 4 parts, and grinding to fineness of not more than 15 mu M to obtain slurry; the polyester resin has a molecular weight of 16000, a hydroxyl value of 4-8 mgKOH/g and an acid value of 0-13 mgKOH/g.

2) Adding polyester resin SKYBON ES 4205 parts, isocyanate DESMODUR 3175SN 3.5 parts and organic tin catalyst DBTL 1 part into the slurry and mixing; adding 56033 parts of amino resin YP, 60000.4 parts of CATALYST, 828EL 2 parts of epoxy resin EPIKOTE, 36001 parts of leveling defoamer EFKA and 88050.8 parts of adhesion promoter TZ, adding 2 parts of solvent S-100# aromatic solvent, 3 parts of isophorone, 1 part of cyclohexanone and 1 part of isobutanol, mixing and filtering to obtain the thick plate polyurethane primer; the filtration is carried out by using a filter bag with the thickness of 80 μm, the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃, the viscosity is 120-140S/coating-4 # cup, and the measurement is carried out at the temperature of 20 ℃, or the filtration is regulated to 500-600 mPa.s.

In this example, the solid content of the polyester resin is 48%, the solid content of the amino resin is 97%, the solid content of the isocyanate is 75%, and the solid content of the epoxy resin is 99%; the ratio of polyester to amino groups was 3.0, the ratio of polyester to isocyanate was 3.3, the ratio of epoxy resin was 0.12, and the ratio of pigments was 1.1.

TABLE 1

TABLE 2

As can be seen from the data in tables 1 and 2:

1. the properties of the slab polyurethane primers obtained in examples 1-7 were all acceptable, but there were differences.

2. The differences in the properties of the slab polyurethane primers obtained in examples 1-7 are: the T-bend of examples 3, 4, 5 is superior to others, and 0T-crack-free can be achieved, and examples 3, 4, 5 have in common that the epoxy resin ratio is 0.11.

Based on this determination, a key factor in determining the T bend of the slab polyurethane primer is the "epoxy ratio" and the optimal ratio is 0.11. The following examples further illustrate the selection of different epoxy ratios.

Example 8

The same as example 5, except that the epoxy resin EPIKOTE 828EL was 1.7 parts, the calculated epoxy resin ratio was 0.1, and the properties obtained are shown in Table 3.

Example 9

The same as example 5, except that the epoxy resin EPIKOTE 828EL was 1.6 parts, the calculated epoxy resin ratio was 0.09, and the properties obtained are shown in Table 3.

Example 10

The same as example 5, except that the epoxy resin EPIKOTE 828EL was 2.2 parts, the calculated epoxy resin ratio was 0.12, and the properties obtained are shown in Table 3.

TABLE 3

As can be seen from the data in Table 3, only the T bend of example 5 is optimal, reaching 0T, and the rest are reduced, so the "epoxy ratio" for best performance is 0.11, and the T bend is reduced when the ratio deviates.

Example 11

The difference from example 1 is that: the amino resin is a mixture of fully methylated melamine resin and high imino methylated melamine resin (volume ratio is 1: 1). The molecular weight of the polyester resin is 10000-12000, and the hydroxyl value is 5-8 mgKOH/g.

The thick plate polyurethane primer prepared in this example is cured at a metal plate temperature of 224 ± 5 ℃, the thickness of the substrate is 2.5mm, the dry coating thickness of the primer is 10 μm, and the performance of the dry coating thickness is 15 μm when matched with a polyester finish with general performance is shown in table 4.

Example 12

The difference from example 1 is that: the acid catalyst is dinonyl naphthalene sulfonic acid blocked acid.

Example 13

The difference from example 1 is that: the acid catalyst is a mixture of p-toluenesulfonic acid, p-toluenesulfonic acid blocked acid and dinonylnaphthalenesulfonic acid (volume ratio is 1: 2: 2).

Example 14

The difference from example 1 is that S-100 in the solvent is changed to S-150.

Example 15

The difference from example 1 is that: step 1) also comprises adding 1 part of dispersant (R-5310 RESIN). The thick plate polyurethane primer prepared in this example is cured at a metal plate temperature of 224 ± 5 ℃, the thickness of the substrate is 2.5mm, the dry coating thickness of the primer is 10 μm, and the performance of the dry coating thickness is 15 μm when matched with a polyester finish with general performance is shown in table 4.

TABLE 4

As can be seen from the data in table 4, the raw materials provided in the selection experiment had no significant effect on the properties of the slab polyurethane primer.

The specific test mode is as follows:

VOC: volatile organic compounds are obtained by testing the specific gravity and solid content of the back finish;

reverse impact: no peeling;

bending test: no peeling;

cupping test: no peeling;

(methyl ethyl ketone ) -resistant MEK: 2 kilogram force round trip times;

acid resistance test: soaking in 10% HCl solution for 24h without abnormality;

alkali resistance test: soaking in 10% NaOH solution for 24h without abnormality;

boiling resistance after grid cutting: after the blades are cut into grids, the water is boiled for 2 hours without abnormity;

salt spray test: spraying 10% NaCl solution to reach the corrosion range of 2mm below the level 3.

Comparative example 1

The polyester resin is ES-600, has a molecular weight of 7000 and a hydroxyl value of 16-20 mgKOH/g, which is the same as that of example 1. The resulting thick plate polyurethane primer T bend was 4T, significantly worse than example 1.

Comparative example 2

The same as example 1, except that the total amount of the polyester resin SKYBON ES 420 added was 17 parts and the amino resin YP5603 was 7 parts.

Calculated as a polyester to amino ratio of 1.2 and a polyester to isocyanate ratio of 2.7. Because of too little polyester and too much amino, the amino self-crosslinking is too much, the film formed by the film is too brittle, the T bend of the obtained thick plate polyurethane primer is 4T, the salt spray resistance is 4 grade in 1000h grade, and the performance is unqualified.

Comparative example 3

The same as example 1, except that DESMODUR 3175SN 1 part of isocyanate and EPIKOTE 828EL 1.4 parts are added.

Calculated as a polyester to isocyanate ratio of 19.2 and an epoxy to resin ratio of 0.06. Because the isocyanate is too little, the resin can not be fully crosslinked, the flexibility is far inferior to that of the primer added with the isocyanate, the T bend of the obtained thick plate polyurethane primer is 4T, the MEK is 80 to-and-fro, and the performance is unqualified.

Comparative example 4

The difference from the example 1 is that the total amount of the polyester resin SKYBON ES 420 is 36 parts, the epoxy resin EPIKOTE 828EL 3 parts, the pigment titanium pigment R-99621 parts and the barium sulfate PRECIPITATED BARIUM SULFATE 5 parts. Calculating to obtain a face-to-face ratio of 0.9; due to the excessively low pigment ratio, the salt spray resistance of the obtained polyurethane primer for the thick plate is 5 grade after 1000h, the polyurethane primer is unqualified, and the hardness is inferior to that of the polyurethane primer in example 1.

Comparative example 5

The same as example 1, except that the total amount of polyester resin SKYBON ES 420 was 36 parts, the amount of amino resin YP5603 was 1 part, and the amount of isocyanate DESMODUR 3175SN was 7 parts.

Calculated as the amino ratio of the polyester was 8.8. The resulting thick plate polyurethane primer had a significantly poor MEK of 70 cycles due to insufficient crosslinking due to the excess polyester.

From the comparison of the results of the examples and comparative examples, it can be seen that:

1. the addition ratio of the resins and the pigment is within a reasonable range (the ratio of the polyester amino to the polyester isocyanate is 2-5, the ratio of the polyester isocyanate to the polyester isocyanate is 3-6, the ratio of the epoxy resin to the epoxy resin is 0.08-0.12, and the ratio of the pigment to the pigment is 1.0-1.8), and the performance meets the standard requirement. Beyond this range, some of the properties do not meet the standards.

2. The qualified range of the epoxy resin ratio is 0.08-0.12, the chemical resistance at the lower limit is poor, the chemical resistance at the upper limit is improved, but the T bend is obviously reduced, and the epoxy resin ratio with the optimal performance is 0.11 by integrating all the performances.

3. The use of the polyester resin with small molecular weight can not meet the T-bend requirement (examination flexibility) on the thick plate, and the application of the saturated polyester resin SKYBON ES 420 with large molecular weight to the thick plate primer can reach the 0T non-stripping requirement.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the invention and are not to be construed as limiting the embodiments of the present invention, and that various other changes and modifications may be made by those skilled in the art based on the above description. All documents mentioned in this application are incorporated by reference into this application as if each were individually incorporated by reference.

Claims

1. The thick plate polyurethane primer is characterized by comprising the following components in parts by weight:

the molecular weight of the polyester resin is 10000-60000, the hydroxyl value is 4-8 mgKOH/g, and the acid value is 0-13 mgKOH/g.

2. The thick plate polyurethane primer according to claim 1, wherein the ratio of polyester to amino is 2-5, the ratio of polyester to isocyanate is 3-6, the ratio of epoxy resin is 0.08-0.12, and the ratio of pigment is 1.0-1.8;

the amino resin is fully methylated melamine resin or a mixture of the fully methylated melamine resin and partial methylated amino resin or a mixture of the fully methylated melamine resin and high imino methylated melamine resin; the solid content of the amino resin is more than or equal to 80 percent.

3. The slab polyurethane primer of claim 1, wherein the isocyanate is a blocked isocyanate.

4. The slab polyurethane primer according to claim 1, wherein the auxiliary comprises the following components in parts by weight:

0.2-0.5 part of an acid catalyst;

0.5-2 parts of an organic tin catalyst;

the acid catalyst is at least one of p-toluenesulfonic acid and blocked acid thereof, dinonyl naphthalenesulfonic acid and blocked acid thereof;

the organic tin catalyst is a blocked polyurethane catalyst; further, dibutyltin dilaurate was used.

5. The slab polyurethane primer according to claim 4, wherein the adjuvant further comprises the following components in parts by weight:

0.1-1 part of anti-settling agent;

0.5-1 part of adhesion promoter;

0.5-1.5 parts of a leveling defoaming agent;

the anti-settling agent is at least one of fumed silica or bentonite; the leveling defoaming agent is an acrylic defoaming agent or a fluorine modified acrylic defoaming agent.

6. The thick plate polyurethane primer according to claim 5, wherein the auxiliary further comprises 0.1-1 parts of a dispersant; the dispersant is a controlled flocculation wetting dispersant.

7. The slab polyurethane primer according to claim 1, wherein the solvent is at least one of an aromatic hydrocarbon solvent, cyclohexanone, isophorone, isobutanol, methyl nylon acid, butyl glycol ether;

the aromatic solvent is at least one of S-100# solvent oil, S-150# solvent oil, trimethylbenzene solvent and durene solvent.

8. The slab polyurethane primer according to claim 1, wherein the pigment is an extender pigment or a coloring pigment, further comprising at least one of barium sulfate, titanium dioxide, calcined kaolin, strontium chrome yellow.

9. A method for preparing the slab polyurethane primer of any one of claims 1 to 8, comprising the steps of:

or:

10. The method for preparing the thick plate polyurethane primer according to claim 9, wherein the minimum film forming temperature of the thick plate polyurethane primer is 200 ℃;

the fineness of grinding is not more than 15 mu m;

the filtration is filtration using a 80 μm filter bag;