A kind of ultra-low acid value alkyd resin aqueous dispersion and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and specifically relates to an ultra-low acid value alkyd resin aqueous dispersion and a preparation method thereof. The aqueous dispersion comprises, by weight: 11 to 20 parts of periodic oleic acid; 1 to 5 parts of dicyclopentadiene, 5 to 10 parts of phthalic anhydride; 0.5 to 1 part of isophthalic acid; 5 to 10 parts of trimethylolpropane; 0.5 to 2 parts of methyl isobutyl ketone solvent; 10 to 15 parts of ethylene glycol monobutyl ether solvent; 0.2 to 0.5 parts of monoethylenically unsaturated carboxylic acid; 5 to 10 parts of styrene, 1 to 5 parts of alkyl methacrylate, 0.2 to 0.5 parts of a reactive emulsifier, 0.5 to 1 part of an initiator, 0.2 to 1 part of a neutralizer; and 35 to 40 parts of deionized water. The alkyd resin aqueous dispersion obtained by the invention has an acid value of ≤15 mgKOH / g, which is very low. The prepared water-based paint has good dry film hydrophobicity, excellent initial water resistance and actual water resistance, excellent storage stability, and other properties such as gloss, hardness, adhesion, etc. are all good.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and specifically relates to an ultra-low acid value alkyd resin aqueous dispersion and a preparation method thereof. Background Art

[0002] Solvent-based air-drying alkyd resin has high gloss, good fullness, good pigment bearing capacity, excellent comprehensive performance, and low price. It is widely used in steel structure coatings, trailer coatings, and interior mechanical coatings. It is the largest solvent-based resin in my country. However, this resin is often diluted to 55-70% solid content with No. 200 solvent oil or No. 190 solvent oil. Both of these organic solvents are VOC components of coatings. The VOC of the solvent-based coatings prepared is ≥420 g / L, resulting in a large amount of solvent waste and not in line with national environmental protection policies.

[0003] Major resin and coating companies in my country are stepping up efforts to replace solvent-based air-drying alkyd resins. The most important and promising alternative resin is water-based alkyd resin. However, there are still many problems with water-based alkyd resins produced at home and abroad. The most prominent of these is the large gap between water resistance, especially initial water resistance, and solvent-based alkyd resins, as well as poor storage stability. There are three main factors for the poor water resistance and storage stability of commercially available water-based alkyd resins: (1) Water-based alkyd resins have a large number of ester bonds. When the dispersion is prepared for painting, water is usually added. At this time, the water-based alkyd resin is under alkaline conditions, and the ester bonds are easily hydrolyzed, which affects the water resistance and storage stability, especially the initial water resistance and storage stability. (2) The molecular weight of water-based alkyd dispersions is usually not large enough, the glass transition temperature is not high, and the evaporation rate of water is very slow, which causes the water-based alkyd resin to dry slowly, which also greatly affects the water resistance of the dispersion, especially the initial water resistance. (3) The solid acid value of the water-based alkyd resin itself is too high. Among the above three factors, the acid value of waterborne alkyd resin has the greatest impact on the water resistance of waterborne alkyd resin, especially the initial water resistance and storage stability. In order to take into account the storage stability of waterborne alkyd resin, the acid value of commercially available waterborne alkyd resin is usually ≥30mgKOH / g. The higher acid value affects the water resistance of waterborne alkyd resin. When the waterborne alkyd resin is ≤30mgKOH / g, the resin is usually not hydrophilic enough, resulting in poor storage stability. Waterborne alkyd resin usually has better storage stability at a higher solid acid value, but poor water resistance.

[0004] At present, the industry generally adopts modification methods to improve the water resistance and storage stability of water-based alkyd resins, but the effect is limited. In the patent CN102643392B "A method for synthesizing a styrene and acrylate modified quick-drying water-based alkyd resin", the alkyd resin is grafted and copolymerized with a vinyl monomer to improve the hardness development speed, but the resin acid value is high (40-60 mgKOH / g), which negatively affects the water resistance of the coating. In the patent CN113831519A "An epoxy resin prepolymer modified water-based alkyd resin and its preparation method", trimellitic anhydride affects the storage stability and the water whitening resistance of the coating is poor. In the patent CN110527413B "An acrylic acid-modified water-based alkyd dispersion and its preparation method and application", there are many synthesis steps and complex processes. In addition, due to the poor controllability of the functionality of the acrylic resin component, the stability of the production batch is very poor, and it is easy to gel in production, and there are great safety risks in large-scale industrial production. Summary of the invention

[0005] In view of the problems existing in the water-based alkyd resin in the prior art, the present invention provides an ultra-low acid value alkyd resin aqueous dispersion and a preparation method thereof, with the aim of providing a water-based alkyd resin aqueous dispersion having water resistance, especially initial water resistance, very close to that of oily alkyd resin and excellent storage stability.

[0006] The technical solution of the present invention is:

[0007] An ultra-low acid value alkyd resin aqueous dispersion, calculated by weight, has a specific formula as follows:

[0008] 11-20 parts of periodic oleic acid;

[0009] 1 to 5 parts of dicyclopentadiene;

[0010] Phthalic anhydride 5-10 parts;

[0011] 0.5-1 part of isophthalic acid;

[0012] 5-10 parts of trimethylolpropane;

[0013] 0.5-2 parts of methyl isobutyl ketone;

[0014] 10-15 parts of ethylene glycol monobutyl ether;

[0015] 0.2 to 0.5 parts of monoethylenically unsaturated carboxylic acid;

[0016] 5-10 parts of styrene;

[0017] 1 to 5 parts of alkyl (meth)acrylate;

[0018] 0.2-0.5 parts of reactive emulsifier;

[0019] Initiator 0.5-1 part;

[0020] Neutralizer 0.2-1 part;

[0021] 35-40 parts of deionized water.

[0022] Furthermore, in the ultra-low acid value alkyd resin aqueous dispersion, the monoethylenically unsaturated carboxylic acid is any one of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, or any combination of any two or more thereof.

[0023] Furthermore, in the ultra-low acid value alkyd resin aqueous dispersion, the (meth)acrylate alkyl ester monomer is any one of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, and isooctyl acrylate, or any combination of any two or more thereof.

[0024] Furthermore, the reactive emulsifier of the ultra-low acid value alkyd resin aqueous dispersion is one or a combination of SR-10 emulsifier and ER-10 emulsifier produced by Shenzhen Xiangrun.

[0025] Furthermore, in the ultra-low acid value alkyd resin aqueous dispersion, the initiator is any one of TBPB, DCP, and BPO or any combination of multiple thereof.

[0026] Furthermore, in the ultra-low acid value alkyd resin aqueous dispersion, the neutralizing agent is any one of diethanolamine, ammonia water, triethylamine, and dimethylethanolamine, or a combination of any two or more thereof.

[0027] The preparation method of the ultra-low acid value alkyd resin aqueous dispersion comprises the following steps:

[0028] (1) Put periodic oleic acid, eleostearic acid, phthalic anhydride, dry isophthalic acid, trimethylolpropane, and methyl isobutyl ketone solvent into a flask, heat it to 160°C in 2 hours, then heat it to 230°C in 7 hours, keep it warm until the acid value is ≤5 mgKOH / g, evacuate for 2-3 hours, then cool it to below 150°C, and dilute it to 75% solid content with ethylene glycol monobutyl ether solvent to obtain alkyd resin intermediate Z-1;

[0029] (2) The alkyd resin intermediate Z-1 is heated to 120-125°C and set aside;

[0030] (3) uniformly mix the monoethylenically unsaturated carboxylic acid, styrene, alkyl (meth)acrylate, reactive emulsifier, and 80% by weight of initiator, and drip into the reaction device over 2-4 hours;

[0031] (4) After dripping, keep warm for 1 hour;

[0032] (5) Add 10% by weight of initiator and continue to keep warm for 1 hour;

[0033] (6) Continue to add 10% by weight of initiator and keep warm for 3 hours;

[0034] (7) Cooling down and adding the remaining ethylene glycol monobutyl ether solvent to dilute;

[0035] (8) Continue to cool down to 85°C, add neutralizer, disperse evenly, and keep warm at 80-90°C;

[0036] (9) Deionized water was added dropwise at 80-90°C for 1.5 hours. After the addition was completed, high-speed dispersion was continued for 1 hour. The temperature was lowered to below 50°C and packaged to obtain an ultra-low acid value alkyd resin aqueous dispersion F-1.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] In a waterborne alkyd resin system without an external emulsifier, the waterborne alkyd resin relies on its own emulsification effect to obtain water dispersibility. Since the emulsification effect of the waterborne alkyd resin itself is poor, the acid value must be increased to improve the emulsification performance of the waterborne alkyd resin itself. As a result, conventional waterborne alkyd resins have a high acid value and poor water resistance, especially initial water resistance.

[0039] The present invention adopts the technical route of acrylic acid modified alkyd, and creatively introduces reactive emulsifiers ER-10 and SR-10 on the basis of drawing on the existing technology, so as to obtain an alkyd resin aqueous dispersion with ultra-low acid value (solid acid value ≤15mgKOH / g).

[0040] The emulsification effect of ER-10 and SR-10 reactive emulsifiers is much better than the emulsification effect of waterborne alkyd resin itself, so that the emulsification of waterborne alkyd resin in water under low acid value conditions can be improved, thereby improving the storage stability of waterborne alkyd resin water dispersion under low acid value conditions. Reactive emulsifiers have no residue after polymerization and have almost no effect on the water resistance of waterborne alkyd resin. Anionic reactive emulsifiers are usually conducive to obtaining dispersions with smaller particle sizes, and nonionic reactive emulsifiers are usually conducive to obtaining dispersions with larger particle sizes but better storage stability and calcium ion stability. In the present invention, nonionic emulsifier ER-10 and anionic emulsifier SR-10 are used in combination for waterborne alkyd resin, which can well adjust the particle size and storage stability of low acid value waterborne alkyd resin water dispersion.

[0041] The present invention further introduces dicyclopentadiene into the base alkyd resin. Dicyclopentadiene is a bridged ring compound, and has no other hydrophilic groups except double bonds on the molecule, so it is very hydrophobic. The structure of dicyclopentadiene is as follows:

[0042]

[0043] Dicyclopentadiene can react with the hydroxyl group on the trihydroxypropane molecule and be introduced into the molecular structure of waterborne alkyd resin. Its huge bridge ring structure forms a synergistic water-repellent effect with the methyl group on the trimethylolpropane molecule, which can greatly improve the hydrophobicity and hydrolysis resistance of waterborne alkyd resin, thereby further improving its water resistance.

[0044] The invention adopts the technical scheme of acrylic acid modification, and the glass transition temperature and molecular weight of the alkyd resin aqueous dispersion are easy to adjust, and the dryness and mechanical properties of the hydrophobic alkyd resin aqueous dispersion can be well guaranteed. DETAILED DESCRIPTION

[0045] In a specific implementation process, the present invention provides an ultra-low acid value alkyd resin aqueous dispersion, which has a specific formula in parts by weight: 11 to 20 parts of periodic oleic acid; 1 to 5 parts of dicyclopentadiene, 5 to 10 parts of phthalic anhydride; 0.5 to 1 part of isophthalic acid; 5 to 10 parts of trimethylolpropane; 0.5 to 2 parts of methyl isobutyl ketone solvent; 10 to 15 parts of ethylene glycol monobutyl ether solvent; 0.2 to 0.5 parts of monoethylenically unsaturated carboxylic acid; 5 to 10 parts of styrene, 1 to 5 parts of alkyl methacrylate, 0.2 to 0.5 parts of reactive emulsifier, 0.5 to 1 part of initiator, 0.2 to 1 part of neutralizer; and 35 to 40 parts of deionized water.

[0046] The present invention will be further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for which specific conditions are not specified in the examples are usually carried out under conventional conditions or under conditions provided by the manufacturer.

[0047] Example 1

[0048] Synthesis of waterborne alkyd resin intermediate Z-1:

[0049] 100g of periodic oleic acid, 10g of dicyclopentadiene, 50g of phthalic anhydride, 5g of isophthalic acid, 55g of trimethylolpropane, and 10g of methyl isobutyl ketone solvent were put into the reaction device, heated to 160°C, and then heated to 230°C for 7 hours for dehydration and esterification. The reaction was kept at 230°C until the resin solid acid value was ≤5mgKOH / g, and then vacuumed for 2 hours to remove the solvent. The temperature was lowered to 150°C, and 68g of ethylene glycol monobutyl ether was added to dilute to 75% solid content to obtain a water-based alkyd resin intermediate Z-1.

[0050] Preparation of waterborne alkyd resin dispersion (F-1):

[0051] Heat the Z-1 obtained in the previous step to 120-125°C for standby use. Then mix 5g of acrylic acid, 50g of styrene, 10g of methyl methacrylate monomer, 2g of SR10 emulsifier produced by Shenzhen Xiangrun, and 4g of TBPB initiator evenly, and then drip them into the reaction device within 3 hours. After dripping, maintain the temperature at 120-125°C for 1 hour. Add 0.5g of TBPB initiator, drip it, keep it warm for 1 hour, continue to add 0.5g of TBPB initiator, drip it, keep it warm for 3 hours, and dilute it with 16g of ethylene glycol monobutyl ether. Continue to cool it to 85°C, add 7g of triethylamine to neutralize and disperse it evenly, keep it warm at 80-90°C, and drip 252g of deionized water for 1.5 hours. After dripping, disperse it at high speed for 1 hour, and continue to cool it to below 50°C for packaging. Finally, an ultra-low acid value alkyd resin aqueous dispersion was obtained with a solid acid value of 13.9 mgKOH / g, a solid content of 44.8%, a rotational viscosity of 3000 cps / 25°C, and a particle size of about 110 nanometers. Example 2

[0052] Synthesis of waterborne alkyd resin intermediate Z-2:

[0053] 100g of periodic oleic acid, 25g of dicyclopentadiene, 50g of phthalic anhydride, 10g of isophthalic acid, 60g of trimethylolpropane, and 10g of methyl isobutyl ketone solvent were put into the reaction device, heated to 160°C, and then heated to 230°C for 7 hours for dehydration and esterification. The reaction was kept at 230°C until the resin solid acid value was ≤5mgKOH / g, and then vacuumed for 2 hours to remove the solvent. The temperature was lowered to 150°C, and 70g of ethylene glycol monobutyl ether was added to dilute to 75% solid content to obtain a water-based alkyd resin intermediate Z-2.

[0054] Preparation of waterborne alkyd resin dispersion (F-2):

[0055] Heat the Z-2 obtained in the previous step to 120-125°C for standby use. Then mix 3g of acrylic acid, 55g of styrene, 10g of methyl methacrylate monomer, 2g of SR10 emulsifier and 2g of ER-10 emulsifier produced by Shenzhen Xiangrun, and 4.2g of TBPB initiator evenly, and then drip them into the reaction device within 3 hours. After dripping, maintain the temperature at 120-125°C for 1 hour. Add 0.5g of TBPB initiator, drip it, keep it warm for 1 hour, continue to add 0.5g of TBPB initiator, drip it, keep it warm for 3 hours, and add 16g of ethylene glycol monobutyl ether to dilute it. Continue to cool it to 85°C, add 4.2g of triethylamine to neutralize and disperse it evenly, keep it warm at 80-90°C, and drip 252g of deionized water for 1.5 hours. After dripping, disperse it at high speed for 1 hour, and continue to cool it to below 50°C for packaging. Finally, an ultra-low acid value alkyd resin aqueous dispersion was obtained, with a solid acid value of 8 mgKOH / g, a solid content of 46%, a rotational viscosity of 2000 cps / 25°C, and a particle size of about 200 nanometers.

[0056] Comparative Example 1 (this comparative example does not contain reactive emulsifier and dicyclopentadiene)

[0057] Synthesis of waterborne alkyd resin intermediate Z-3:

[0058] 100g of periodic oleic acid, 50g of phthalic anhydride, 60g of trimethylolpropane, and 10g of methyl isobutyl ketone solvent were put into the reaction device, heated to 160°C, and then heated to 230°C for 7 hours for dehydration and esterification. The reaction was kept at 230°C until the resin solid acid value was ≤5mgKOH / g, and then vacuumed for 2 hours to remove the solvent. The temperature was lowered to 150°C, and 70g of ethylene glycol monobutyl ether was added to dilute to 75% solid content to obtain a water-based alkyd resin intermediate Z-3.

[0059] Preparation of water-based alkyd resin dispersion (F-3) without reactive emulsifier and dicyclopentadiene:

[0060] Heat the Z-3 obtained in the previous step to 120-125°C for standby use. Then mix 8g of acrylic acid, 55g of styrene, 10g of methyl methacrylate monomer, and 4.2g of TBPB initiator evenly, and then drip them into the reaction device within 3 hours. After dripping, maintain the temperature at 120-125°C for 1 hour. Add 0.5g of TBPB initiator, drip it, keep it warm for 1 hour, continue to add 0.5g of TBPB initiator, drip it, keep it warm for 3 hours, and add 16g of ethylene glycol monobutyl ether to dilute it. Continue to cool it to 85°C, add 11.2g of triethylamine to neutralize and disperse it evenly, keep it warm at 80-90°C, and drip 248g of deionized water for 1.5 hours. After dripping, disperse it at high speed for 1 hour, and continue to cool it to below 50°C for packaging. The solid acid value of the dispersion is 21mgKOH / g, the solid content is 40%, and the rotational viscosity is 20000cps / 25℃. The dispersion is extremely thixotropic. After 10 minutes of static state, the dispersion solidifies. Under stirring, the dispersion shows obvious shear thinning. After 1 day of hot storage at 50℃, water is seriously separated.

[0061] The water-based alkyd resin of the above embodiment and comparative example is used in combination with a general-purpose water-based alkyd resin trailer paint for bottom and surface, and the dry film thickness is 40-60 μm. The specific performance is shown in Table 1.

[0062] Table 1 Performance test of examples and comparative examples

[0063] Numbered test items Example 1 Example 2 Comparative Example 1 Comparative Example 2 (389-9 solvent-based alkyd resin from a certain company) Solid 44.8 46 40 55 Viscosity 3000 2000 20000 1500 Solid acid value (mgKOH / g) 13.9 8 21 16 mgKOH / g pH 7.5 8 7.3 / Particle size (nm) 110 200 150 / Storage stability (50°C) 30 days 30 days 1 day 30 days Pencil hardness B B 2B 2B Gloss (60°) 92 90 75 88 Adhesion (grid spacing 1mm) Level 0 Level 0 Level 0 Level 0 Initial water resistance (self-drying for 4 hours) 240 hours 240 hours 96 hours 264 hours Storage stability (50°C) 30 days 30 days 1 day 30 days VOC in coating application 250 g / L 260 g / L 230 g / L 480 g / L

[0064] The above test results are the resin properties obtained by testing the water-based steel structure coatings configured with the resins of the embodiments and comparative examples. The test results show that the hydrophobic alkyd resin aqueous dispersion obtained by grafting acrylic acid with a reactive emulsifier in the present invention has an initial water resistance that is basically equivalent to that of the oily air-dried alkyd resin, excellent storage stability, and other properties such as gloss, hardness, and mechanical properties are good. The acid value of the alkyd resin aqueous dispersion that is not grafted with a reactive emulsifier is relatively high, but is less than 30 mgKOH / g, so the water resistance and storage stability are poor.

[0065] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An ultra-low acid value alkyd resin aqueous dispersion, characterized in that: The specific formula is as follows by weight: 11-20 parts of periodic oleic acid; 1 to 5 parts of dicyclopentadiene; Phthalic anhydride 5-10 parts; 0.5-1 part of isophthalic acid; 5-10 parts of trimethylolpropane; 0.5-2 parts of methyl isobutyl ketone; 10-15 parts of ethylene glycol monobutyl ether; 0.2 to 0.5 parts of monoethylenically unsaturated carboxylic acid; 5-10 parts of styrene; 1 to 5 parts of alkyl (meth)acrylate; 0.2-0.5 parts of reactive emulsifier; Initiator 0.5-1 part; Neutralizer 0.2-1 part; 35-40 parts of deionized water; The reactive emulsifier is one or a combination of SR-10 emulsifier and ER-10 emulsifier; The ultra-low acid value alkyd resin aqueous dispersion is prepared by the following steps: (1) Put periodic oleic acid, dicyclopentadiene, phthalic anhydride, isophthalic acid, trimethylolpropane, and methyl isobutyl ketone solvent into a flask, heat it to 160°C in 2 hours, then heat it to 230°C in 7 hours, keep it warm until the acid value is ≤5 mgKOH / g, evacuate for 2-3 hours, then cool it to below 150°C, and dilute it to 75% solid content with ethylene glycol monobutyl ether solvent to obtain alkyd resin intermediate Z-1; (2) The alkyd resin intermediate Z-1 is heated to 120-125°C and set aside; (3) uniformly mix the monoethylenically unsaturated carboxylic acid, styrene, alkyl (meth)acrylate, reactive emulsifier, and 80% by weight of initiator, and drip into the reaction device over 2-4 hours; (4) After dripping, keep warm for 1 hour; (5) Add 10% by weight of initiator and continue to keep warm for 1 hour; (6) Continue to add 10% by weight of initiator and keep warm for 3 hours; (7) Cooling down and adding the remaining ethylene glycol monobutyl ether solvent to dilute; (8) Continue to cool down to 85°C, add neutralizer, disperse evenly, and keep warm at 80-90°C; (9) Deionized water was added dropwise at 80-90°C for 1.5 hours. After the addition was completed, high-speed dispersion was continued for 1 hour. The temperature was lowered to below 50°C and packaged to obtain an ultra-low acid value alkyd resin aqueous dispersion F-1.

2. The ultra-low acid value alkyd resin aqueous dispersion according to claim 1, characterized in that: The monoethylenically unsaturated carboxylic acid is any one of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, or any combination of any two or more thereof.

3. The ultra-low acid value alkyd resin aqueous dispersion according to claim 1, characterized in that: The (meth)acrylic acid alkyl ester monomer is any one of methyl methacrylate, n-butyl acrylate, n-butyl methacrylate and isooctyl acrylate, or any combination of any two or more thereof.

4. The ultra-low acid value alkyd resin aqueous dispersion according to claim 1, characterized in that: The initiator is any one of TBPB, DCP and BPO or any combination of multiple thereof.

5. The ultra-low acid value alkyd resin aqueous dispersion according to claim 1, characterized in that: The neutralizing agent is any one of diethanolamine, ammonia water, triethylamine and dimethylethanolamine or a combination of any two or more thereof.

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