CN105176155A - UV cured cathode electrophoresis paint with side chain containing ammonium salt positive ions and preparation method therefor - Google Patents

Abstract

The invention relates to a UV-cured cathodic electrophoretic coating containing ammonium salt cations in the side chain and a preparation method thereof. The resin of the electrophoretic coating contains: (1) polyurethane with side group ammonium salt cations, the total weight of this component is 40-60wt.% of the total weight of the resin; (2) acrylates with two or more functionalities , the total weight of this component is 40-60wt.% of the total weight of the resin. The invention relates to the preparation of side group-containing tertiary amine dihydric alcohol and the preparation method of UV-cured cathodic electrophoretic paint containing ammonium salt cations in the side chain.

Description

A kind of UV curing cathodic electrophoretic coating containing ammonium salt cation in side chain and preparation method thereof

technical field

The invention belongs to the field of fine chemicals, and in particular relates to a UV-cured cathodic electrophoretic coating with side chains containing ammonium salt cations and a preparation method thereof.

Background technique

Cathodic electrophoretic coatings are widely used in automotive primers, building materials, household appliances, toys and other fields due to their excellent anti-corrosion properties, dense and uniform coating, high degree of coating automation, and high throwing power. The traditional cathodic electrophoretic coating adopts thermal curing method, and the curing temperature is high, generally 140-180°C. Even the low-temperature cathodic electrophoretic coating has a curing temperature of 85-110°C, and the curing time is longer (more than 20min). , not only consumes energy but also limits the application on heat-sensitive materials. UV curable cathodic electrophoretic coating adopts ultraviolet light curing method, which has the advantages of low curing temperature, short curing time and energy saving. Therefore, UV curable cathodic electrophoretic coating has become a new direction for the development of electrophoretic coatings.

In the existing research on UV-cured cathodic electrophoretic coatings, the matrix resins mainly include polyurethane resins, acrylic resins, and epoxy resins. Polyurethane resin is a typical block polymer. Compared with the latter two resins, the performance of polyurethane system is more variable and controllable, so it is a more promising functional material. In polyurethane cathodic electrophoretic coatings, N-methyldiethanolamine is generally used to introduce tertiary amine groups. The tertiary amine introduced in this way is located on the main chain of polyurethane. The water base is wrapped in the polyurethane particles and cannot achieve the hydrophilic effect, so it is necessary to add more monomers containing tertiary amines when preparing polyurethane dispersions.

In the patent US6232364, a cationic electrodeposition ultraviolet curable coating is synthesized by using a tertiary amine diol whose tertiary amino group is located in the main chain. Wherein the tertiary amine diol is a compound containing the following general formula, including N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine and the like.

R is an alkyl group containing 4 or fewer carbon atoms

In the present invention, a new cationic functional monomer is synthesized by using binary glycidyl ether and monovalent secondary amine. The functional monomer contains two tertiary amine groups, and the two tertiary amine groups are at side positions. The functional monomer The structure is as follows:

R ₁ is C _2-10 alkyl, aryl, etc.;

R ₂ are the same or different C _1-6 alkyl groups.

After the synthesized monomer reacts with isocyanate, diol, etc., the tertiary amine group with cationic hydrophilic dispersion function is not on the main chain, but is suspended on the side chain of polyurethane in the form of side group. This pendant tertiary amine group can provide more effective hydrophilic ability and dispersion stability, and play a catalytic role in the synthesis of polyurethane. After synthesizing the polyurethane, add an acrylate monomer with a difunctional or higher functionality, stir evenly, add water and disperse to obtain a UV-curable cathodic electrophoretic coating.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings existing in the prior art, and to provide a preparation method of a UV-cured cathodic electrophoretic coating containing ammonium salt cations in the side chain.

The present invention is realized through the following technical solutions.

A kind of cathodic electrophoretic coating that the UV curing of side chain contains ammonium salt cation, the resin of this coating comprises following component:

(1) Polyurethane containing side group ammonium salt cations, the total weight of this component is 40-60wt.%, based on the total weight of the resin as 100wt.%.

(2) For acrylates with two or more functionalities, the total weight of this component is 60-40 wt.%, calculated as 100 wt.% based on the total weight of the resin.

The method for preparing the cathodic electrophoretic coating of the UV curing of above-mentioned a kind of side chain containing ammonium salt cation, concrete steps are as follows:

1) Add diglycidyl ether in a four-necked round bottom flask;

2) Drop in the secondary amine, the temperature is controlled at 60-80°C, after the drop is completed, the temperature is controlled at 70-80°C, and the temperature is kept for 2.0-4.0h;

3) monitoring the reaction by infrared;

4) After the reaction is finished, remove the remaining secondary amine to obtain a diol monomer containing a side group tertiary amine;

5) At 100-110°C, remove water from the polyester diol under reduced pressure;

6) Add diisocyanate and diol monomer containing pendant tertiary amine respectively, and react at 80-90°C for 2.0-4.0h to obtain polyurethane;

7) measure remaining-NCO value with di-n-butylamine method;

8) After the remaining -NCO value reaches the theoretical value of 0.39-1.90 wt%, cool down, add acetone to dilute, and then add ethanolamine to block;

9) Add lactic acid for neutralization, then add acrylate and photoinitiator, and finally add deionized water to disperse, remove acetone, and obtain the desired coating.

Further, the diol monomer containing side group tertiary amine in step 4) is prepared by reacting diglycidyl ether and mono-secondary amine, and the molar ratio of diglycidyl ether and mono-secondary amine is 1:2.05-1: 2.3.

Further, the polyester diol in step 5) is polyethylene glycol, polypropylene glycol, polytetramethylene glycol or polycaprolactone diol with a number average molecular weight of 200-1000 g/mol.

Further, the polyurethane described in step 6) adopts a diol containing a side group tertiary amine as a monomer, and the monomer structure is as follows:

Wherein R ₁ is C _2- C ₁₀ alkyl or aryl; R ₂ is the same or different C _1- C ₆ alkyl.

Further, the polyurethane described in step 6) is prepared by reacting a diol monomer containing a side group tertiary amine, polyester diol and diisocyanate; the molecular weight of the polyurethane is 5,000-50,000.

Further, the diisocyanate in step 6) is 1,5-pentane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1,3-tetramethylxylylene diisocyanate isocyanate or 1,3-xylylene diisocyanate.

Further, the acrylate in step 9) is binary epoxy acrylate with two or more functionalities, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, polyethylene glycol diacrylate ester, 1,9-nonanediol diacrylate, ethoxylated bisphenol A di(meth)acrylate, polyethylene glycol diacrylate, trimethylol triacrylate, ethoxylated trimethylolpropane tri Acrylates, pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylate, di-trimethylolpropane tetraacrylate or dipentaerythritol hexaacrylate.

Further optimally, the functional monomer, that is, the side group-containing tertiary amine diol is synthesized through the following steps: add diglycidyl ether into a four-necked round-bottomed flask equipped with a condenser, a stirrer, and a thermometer, and pass through a constant pressure funnel Add secondary amine drop by drop, control the temperature at 60-80°C, and control the molar ratio of diglycidyl ether to secondary amine at 1:2.05-1:2.3. The secondary amine was dropped within about 1.5 hours. After the drop, the temperature was controlled at 70-80°C, and the temperature was kept for 3.0 hours. There was no vibration absorption peak of epoxy group at 915cm ^-1 by infrared detection, indicating that the reaction had been completed. After the reaction was finished, the remaining secondary amine was removed under reduced pressure by a vacuum pump. It was confirmed by ¹³ CNMR that the target product had been obtained.

The diglycidyl ether is 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, neopentyl Diol diglycidyl ether or bisphenol A diglycidyl ether, preferably 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and bisphenol A diglycidyl ether. The secondary amine is diethylamine, methylethylamine, di-n-butylamine or di-n-hexylamine, preferably diethylamine and methylethylamine. The molar ratio of diglycidyl ether to secondary amine is 1:2.05-1:2.6, preferably 1:2.05-1:2.3.

Further optimized: remove water from the polyester diol under reduced pressure at 100-110° C. for 1.5 h. Add metered diisocyanate and the synthesized diol functional monomer containing side group tertiary amine respectively, react at 80-90°C for about 2.0h, and measure the remaining -NCO value by di-n-butylamine method. After the remaining -NCO value reaches the theoretical value, cool down, add acetone to dilute, and add ethanolamine equivalent to the remaining -NCO to block, and react for about 15 minutes. After adding lactic acid for neutralization, add acrylate containing 2 or more functional groups and 3% to 5% photoinitiator, add deionized water at high speed to disperse until the solid content is 10% to 15%, and use a vacuum pump to depressurize Acetone was removed to obtain the desired coating.

The diols include but are not limited to: polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycaprolactone diol with a number average molecular weight of 200-1000 g/mol. Diisocyanates include but are not limited to: 1,5-pentane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 2,4,4-trimethyl Hexamethylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate (TDI), 1,5-naphthalene diisocyanate, 1,3-tetramethyl Xylylene Diisocyanate (TMXDI), 1,3-Xylylene Diisocyanate (XDI). Acrylates with two or more functionalities include but are not limited to: binary epoxy acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, polyethylene glycol diacrylate, 1,9 - Nonanediol Diacrylate, Ethoxylated Bisphenol A Di(meth)acrylate, Polyethylene Glycol Diacrylate, Trimethylol Triacrylate, Ethoxylated Trimethylolpropane Triacrylate, Pentaerythritol Triacrylate Acrylates, ethoxylated pentaerythritol tetraacrylate, di-trimethylolpropane tetraacrylate or dipentaerythritol hexaacrylate. The mass of polyurethane accounts for 40-60% of the total mass of the resin, and the mass of acrylate accounts for 40-60% of the total mass of the resin; the molecular weight of polyurethane is 5,000-50,000; Prepared by reaction of ester diol and diisocyanate.

The stainless steel sheet is used as the anode, the tinplate sheet is used as the cathode, the cathode area:anode area is 4:1-6:1, the pole distance is 15cm-20cm, the electrophoresis voltage is set to 60V, and the electrophoresis time is 45s. The cathode tinplate sheet needs to be sanded to remove the surface oxide layer before use, and wiped clean with ethanol. After the electrophoresis is completed, rinse off the floating paint on the surface with slow water. After cleaning, put the iron sheet into a drying oven and bake at 70°C for about 5-10 minutes to remove residual moisture. After the iron sheet is dried, it is cured in a UV curing machine, and the curing conditions are as follows: high-pressure mercury lamp is used for curing, and the energy is 750mj/cm ² . After the paint film is cured, test the pencil hardness and attachment of the paint film according to the national standard GB/T6739-2006 "Determination of paint film hardness by pencil method of paint and varnish" and GB/T9286-1998 "cross-cut test of paint and varnish film". Focus on simultaneously measuring the flexibility and alcohol resistance of paint films.

Compared with the prior art, the present invention has the following advantages and technical effects: (1) because the ammonium salt cation is in the polyurethane side group, the degree of freedom is larger, so that the polyurethane has excellent water dispersibility; (2) the polyurethane provides Good flexibility is provided, and epoxy acrylate provides hardness, so that the paint film has good flexibility and hardness at the same time.

Description of drawings

Figure 1 is the ¹³ C_NMR chart of side chain tertiary amine monomer DDDOD.

Detailed ways

The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto.

Example 1

Put 50.0g of 1,4-butanediol diglycidyl ether into a 250mL four-necked round-bottomed flask, add 40.0g of diethylamine dropwise through a constant pressure funnel under stirring, and control the temperature at 60-80°C for 1.5h After dripping, keep the temperature for 3.0 hours, and judge the complete reaction by observing the vibration absorption peak at 910 cm ^-1 in the infrared spectrogram without epoxy group. After the reaction was finished, the remaining diethylamine was removed under reduced pressure by a vacuum pump. The synthesis route of the diol monomer 7,12-dioxo-3,16-diaza-3,16-diethyl-5,14-octadecanediol (DDDOD) containing pendant tertiary amine is as follows:

Figure 1 ¹³ C_NMR spectrum shows that DDDOD has been synthesized.

Example 2

Add 24.0g of synthesized diol monomer containing side group tertiary amine, 126.5g polycaprolactone diol 1000 (PCL1000), 49.5g polycaprolactone diol 1000 (PCL1000) and Isophorone diisocyanate (IPDI), react at 80°C for about 2.0h, titrate the remaining amount of -NCO with the di-n-butylamine method, until the -NCO content reaches the theoretical value of 1.56wt%, cool down to 30°C, and add 200g of acetone Dilute, then add 4.54g ethanolamine to block, react for 15 minutes, add 10.64g lactic acid for neutralization, and obtain polyurethane solution A containing cations.

Example 3

Get the cation-containing polyurethane solution A40g prepared above, add 30g epoxy acrylate, 0.5g photoinitiator 1-hydroxycyclohexyl phenyl ketone, 0.5g photoinitiator 2-hydroxyl-2-methyl -1-Phenyl-1-acetone, after stirring evenly, add deionized water to disperse under 1000rpm high-speed stirring, evaporate acetone under reduced pressure to obtain a dispersion, dilute it with deionized water dispersion to a solid content of 15% , to obtain the cationic photo-curable cathodic electrophoretic coating containing side groups of the present invention.

Example 4

Get the cation-containing polyurethane solution A50g prepared in Example 2, add 25g epoxy acrylate, 0.5g photoinitiator 1-hydroxycyclohexyl phenyl ketone, 0.5g photoinitiator 2-hydroxyl-2 -Methyl-1-phenyl-1-acetone, after stirring evenly, add deionized water to disperse under high-speed stirring at 1000rpm, evaporate acetone under reduced pressure to obtain a dispersion, dilute with deionized water dispersion to a solid content of 15%, to obtain the cationic photo-curable cathodic electrophoretic coating containing side groups of the present invention.

Example 5

Get the cation-containing polyurethane solution A50g prepared in Example 2, add 25g pentaerythritol triacrylate, 0.5g photoinitiator 1-hydroxycyclohexyl phenyl ketone, 0.5g photoinitiator 2-hydroxyl-2 -Methyl-1-phenyl-1-acetone, after stirring evenly, add deionized water to disperse under high-speed stirring at 1000rpm, evaporate acetone under reduced pressure to obtain a dispersion, dilute with deionized water dispersion to a solid content of 15%, to obtain the cationic photo-curable cathodic electrophoretic coating containing side groups of the present invention.

Example 6

Get the cation-containing polyurethane solution A50g prepared in Example 2, add 25g dipentaerythritol hexaacrylate, 0.5g photoinitiator 1-hydroxycyclohexyl phenyl ketone, 0.5g photoinitiator 2-hydroxyl- 2-Methyl-1-phenyl-1-propanone, after stirring evenly, add deionized water to disperse under high-speed stirring at 1200/rpm, distill off acetone under reduced pressure to obtain a dispersion, dilute with deionized water dispersion to The solid content is 15%, and the cationic photo-curable cathodic electrophoretic coating containing side groups of the present invention is obtained.

Table 1

The test results of hardness, adhesion, flexibility and alcohol resistance of the paint film are shown in Table 1. The test is carried out as follows.

Hardness: Tested according to the national standard GB/T6739-2006 "Determination of paint film hardness by pencil method for paints and varnishes".

Adhesion: GB/T9286-1998 "Cross-cut test of paint and varnish film.

180° bending test: Bend the test piece at an angle of 180° to observe whether the paint film is cracked.

Alcohol resistance: Put a small ball of cotton on the tinplate sheet to make the paint film, drop 100% ethanol on the cotton, leave it for 1 hour, and observe whether there are blisters, cracks, peeling and other damage on the iron sheet. Keep the cotton moistened with ethanol during the test.

Claims (8)

1. the cathodic electrophoretic coating of UV curing that a kind of side chain contains ammonium salt cation, it is characterized in that the resin in this coating comprises following component: (1) the polyurethane that contains side group ammonium salt cation, the gross weight of this component is 40-60wt.%, based on the total weight of the resin as 100wt.%; (2) For acrylates with two or more functionalities, the total weight of this component is 60-40wt.%, based on the total weight of the resin as 100wt.%. 2. prepare the method for the cathodic electrophoretic coating of the UV curing of a kind of side chain containing ammonium salt cation described in claim 1, it is characterized in that, preparation step is as follows: 1) Add diglycidyl ether in a four-necked round bottom flask; 2) Drop in the secondary amine, the temperature is controlled at 60-80°C, after the drop is completed, the temperature is controlled at 70-80°C, and the temperature is kept for 2.0-4.0h; 3) monitoring the reaction by infrared; 4) After the reaction is finished, remove the remaining secondary amine to obtain a diol monomer containing a side group tertiary amine; 5) At 100-110°C, remove water from the polyester diol under reduced pressure; 6) Add diisocyanate and diol monomer containing pendant tertiary amine respectively, and react at 80-90°C for 2.0-4.0h to obtain polyurethane; 7) measure remaining-NCO value with di-n-butylamine method; 8) After the remaining -NCO value reaches the theoretical value of 0.39-1.90 wt%, cool down, add acetone to dilute, and then add ethanolamine to block; 9) Add lactic acid for neutralization, then add acrylate and photoinitiator, and finally add deionized water to disperse, remove acetone, and obtain the desired coating. 3. the preparation method of the cathodic electrophoretic paint that a kind of side chain contains the UV curing of ammonium salt cation according to claim 2, it is characterized in that, step 4) described containing side group tertiary amine glycol monomer is made of two It is prepared by reacting glycidyl ether and mono-secondary amine. The molar ratio of diglycidyl ether and mono-secondary amine is 1:2.05-1:2.3. 4. the preparation method of the cathodic electrophoretic coating of the UV curing of a kind of side chain containing ammonium salt cation according to claim 2, it is characterized in that, step 5) described polyester diol is that number average molecular weight is 200-1000g/ mol of polyethylene glycol, polypropylene glycol, polytetramethylene glycol or polycaprolactone diol. 5. the preparation method of the cathodic electrophoretic coating of the UV curing of a kind of side chain containing ammonium salt cation according to claim 2, it is characterized in that, step 6) described polyurethane adopts the dibasic alcohol that contains side group tertiary amine as unit body, the monomer structure is as follows: Wherein R ₁ is C _2- C ₁₀ alkyl or aryl; R ₂ is the same or different C _1- C ₆ alkyl. 6. the preparation method of the cathodic electrophoretic coating of the UV curing of a kind of side chain containing ammonium salt cation according to claim 2, it is characterized in that, step 6) described polyurethane adopts to contain side group tertiary amine glycol monomer, It is produced by the reaction of polyester diol and diisocyanate; the molecular weight of polyurethane is 5,000-50,000. 7. the preparation method of the cathodic electrophoretic paint of a kind of side chain containing ammonium salt cation according to claim 2 is characterized in that, step 6) described diisocyanate is 1,5-pentane diisocyanate, 1 ,6-Hexamethylene diisocyanate, Isophorone diisocyanate, 2,4,4-Trimethylhexamethylene diisocyanate, 1,4-Cyclohexylene diisocyanate, 1,4-Benzene diisocyanate , 2,4-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1,3-tetramethylxylylene diisocyanate or 1,3-xylylene diisocyanate. 8. the preparation method of the cathodic electrophoretic paint of a kind of side chain containing ammonium salt cation according to claim 2 is characterized in that, step 9) described acrylic acid ester is two or more than two functionalities Epoxy acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, polyethylene glycol diacrylate, 1,9-nonanediol diacrylate, ethoxylated bisphenol A bis(methyl base) acrylate, polyethylene glycol diacrylate, trimethylol triacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylate, di-trimethylolpropane Propane tetraacrylate or dipentaerythritol hexaacrylate.