Cardanol modified water-based emulsion and preparation method thereof

Abstract

The invention relates to the technical field of water-based paint, in particular to anacardol modified water-based emulsion and a preparation method thereof. The preparation raw materials comprise cardanol, polyhydric alcohol, polybasic acid, an acrylic acid monomer, a catalyst, a neutralizer, an initiator, an organic solvent and water. By limiting the molar ratio of the cardanol to the polybasic acid to the polyhydric alcohol to be (0.8-1.5): 1: (1.02-1.05), the drying speed, hardness, water resistance and corrosion resistance of the emulsion can be improved; the acrylic monomers comprise styrene, butyl acrylate, methyl methacrylate and methacrylic acid, and the weight ratio of the styrene to the butyl acrylate to the methyl methacrylate to the methacrylic acid is limited to be 2: (1-3): (5-6): (0.2-0.5), so that the adhesive force and the salt spray resistance of the emulsion can be further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based coatings, and in particular to a cardanol-modified water-based emulsion and a preparation method thereof. Background Art

[0002] With the vigorous development of the country's industry, environmental protection has become an important issue that cannot be avoided. In this context, water-based industrial paints, as representatives of environmentally friendly paints, have emerged in the market, aiming to replace traditional solvent-based paints to reduce pollution to the environment. However, the water-based industrial paints on the current market are not perfect, and they each have some defects. Among them, water-based alkyd paints, although they are environmentally friendly, have mediocre water resistance, hardness and drying performance, which is difficult to meet the needs of high-end coatings. Water-based acrylic dispersions, although they dry quickly, have a large particle size, resulting in low gloss, and are prone to rust after long-term use, affecting the durability and aesthetics of the coating.

[0003] Chinese invention patent CN 106519199A discloses a method for preparing a modified tung oil alkyd resin. The method uses tung oil, glycerol and anhydride to prepare tung oil alkyd resin. Then, the unsaturated double bonds on the tung oil are reacted with isobornyl acrylate to prepare a modified tung oil alkyd resin, which has poor water resistance and salt spray resistance. Chinese invention patent CN105705545A discloses a paint-based resin, which is a plasticized epoxy-amine adduct P, and the adduct P includes an adduct EA made of epoxy resin E and amine A, which is optionally modified by incorporating unsaturated fatty acid F'. The resin has good salt spray resistance, but poor drying performance. Summary of the invention

[0004] The first aspect of the present invention provides a cardanol-modified aqueous emulsion, wherein the raw materials for preparing the emulsion include: cardanol, polyol, polyacid, acrylic monomer, catalyst, neutralizer, initiator, organic solvent and water.

[0005] The molar ratio of the cardanol, the polyacid and the polyol is (0.8-1.5):1:(1.02-1.05).

[0006] The present application has found that by limiting the molar ratio of cardanol, polyacid and polyol to (0.8-1.5):1:(1.02-1.05), the drying speed, hardness, water resistance and corrosion resistance of the emulsion can be improved. It may be that cardanol contains a large number of unsaturated double bonds while containing benzene rings, which interact with the active groups in polyacids and polyols to improve the rigidity and oxidative crosslinking speed of the emulsion polymer. Further research has found that acrylic monomers include styrene, butyl acrylate, methyl methacrylate and methacrylic acid, and the weight ratio of styrene, butyl acrylate, methyl methacrylate and methacrylic acid is limited to 2:(1-3):(5-6):(0.2-0.5), which can further improve the adhesion and salt spray resistance of the emulsion. The rigid structure of styrene enhances the interaction between polymer segments and effectively improves the salt spray performance, but the rigid structure reduces the adhesion to a certain extent. The flexibility of butyl acrylate and methyl methacrylate helps to improve the wettability of the coating, making it easier for the coating to penetrate into the surface of the substrate, thereby improving the adhesion. At the same time, methacrylic acid is added as a functional monomer, which mainly introduces reactive groups in the coating compounding, participates in the polymerization reaction, and forms a polymer with a specific three-dimensional network structure.

[0007] Preferably, the molar ratio of the cardanol, the polyacid and the polyol is (0.8-1.3):1:(1.02-1.05).

[0008] The polyol includes at least one of ethylene glycol, 1,2- and 1,3-propylene glycol, neopentyl glycol, diethylene glycol, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitol.

[0009] Preferably, the polyol comprises trimethylolpropane.

[0010] The polyacid includes at least one of phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, fumaric acid, maleic anhydride, sebacic acid or pyromellitic anhydride.

[0011] Preferably, the polyacid comprises phthalic anhydride.

[0012] The acrylic monomer includes at least one of styrene, butyl acrylate, methyl methacrylate and methacrylic acid.

[0013] The acrylic monomers include styrene, butyl acrylate, methyl methacrylate and methacrylic acid, and the weight ratio of styrene, butyl acrylate, methyl methacrylate and methacrylic acid is 2:(1-3):(5-6):(0.2-0.5).

[0014] Preferably, the weight ratio of styrene, butyl acrylate, methyl methacrylate and methacrylic acid is 2:2:(5-6):(0.2-0.5).

[0015] The organic solvent includes at least one of xylene, methyl isobutyl ketone, ethylene glycol monobutyl ether, propylene glycol butyl ether, and propylene glycol methyl ether acetate.

[0016] Preferably, the organic solvent includes xylene and propylene glycol butyl ether.

[0017] The catalyst comprises at least one of triethylamine, triethanolamine, diethanolamine, m-xylylenediamine, diaminophenylmethane, 2,4,6-tris(dimethylaminomethyl)phenol, tetraethylammonium bromide and tetrabutylammonium chloride.

[0018] Preferably, the catalyst comprises triethylamine.

[0019] The neutralizing agent includes at least one of dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, maline, triethanolamine, and sodium hydroxide.

[0020] Preferably, the neutralizing agent comprises dimethylethanolamine.

[0021] The initiator comprises at least one of di-tert-butyl peroxide, benzoyl peroxide, diisopropylbenzene peroxide, tert-butyl peroxide isopropylbenzene, 1,1-bis(tert-hexylperoxide)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, tert-butyl peroxyisooctanoate and benzoic acid peroxide.

[0022] Preferably, the initiator comprises benzoic acid peroxide.

[0023] The second aspect of the present invention provides a method for preparing a cardanol-modified aqueous emulsion, comprising the following steps:

[0024] S1, mixing cardanol, polyacid, catalyst and xylene to react to obtain a first mixture;

[0025] S2, adding a polyol to the first mixture to react to obtain a second mixture;

[0026] S3, extracting xylene from the second mixture and adding propylene glycol butyl ether to obtain a third mixture;

[0027] S4, mixing acrylic monomers uniformly, adding initiators and mixing uniformly, to obtain a fourth mixture;

[0028] S5, adding the fourth mixture dropwise to the third mixture, and then adding a neutralizer and water respectively, and emulsifying to obtain a cardanol-modified aqueous emulsion.

[0029] The reaction temperature in step S1 is 160-190°C, and the reaction temperature in step S2 is 190-220°C.

[0030] Preferably, the reaction temperature in step S1 is 170-180°C, and the reaction temperature in step S2 is 200-210°C.

[0031] The acid value of the first mixture is not higher than 130 mgKOH / g, and the acid value of the second mixture is not higher than 10 mgKOH / g.

[0032] The dripping time in step S5 is 2-5 hours.

[0033] Preferably, the dripping time in step S5 is 2.5-3h.

[0034] Beneficial Effects

[0035] 1. By limiting the molar ratio of cardanol, polyacid and polyol to (0.8-1.5):1:(1.02-1.05), the drying speed, hardness, water resistance and antiseptic properties of the emulsion can be improved.

[0036] 2. By limiting the molar ratio of cardanol, polyacid and polyol to (0.8-1.3):1:(1.02-1.05), the drying speed (surface drying) can be controlled within 40 minutes.

[0037] 3. The acrylic monomers include styrene, butyl acrylate, methyl methacrylate and methacrylic acid, and the weight ratio of styrene, butyl acrylate, methyl methacrylate and methacrylic acid is limited to 2:(1-3):

[0038] (5-6): (0.2-0.5), which can further improve the adhesion and salt spray resistance of the emulsion.

[0039] 4. The paint film prepared by the emulsion of this application has a glossiness of up to 90 and a pencil hardness of up to 3H.

[0040] 5. The main raw material of this application, cardanol, is cheap and easily available, which effectively reduces the production cost of the emulsion. DETAILED DESCRIPTION

[0041] Example 1

[0042] A cardanol-modified aqueous emulsion, prepared from the following raw materials: cardanol (Vietnam), polyol (trimethylolpropane), polyacid (phthalic anhydride), acrylic monomer, catalyst (triethylamine), neutralizer (dimethylethanolamine), initiator (benzoic acid peroxide), organic solvent and water.

[0043] The acrylic monomers are styrene, butyl acrylate, methyl methacrylate and methacrylic acid in a mass ratio of 2:2:5:0.2.

[0044] The molar ratio of the cardanol, the polyacid and the polyol is 1.3:1:1.02.

[0045] The organic solvents are xylene and propylene glycol butyl ether.

[0046] A method for preparing a cardanol-modified aqueous emulsion comprises the following steps:

[0047] S1, mixing cardanol, polyacid, catalyst and xylene, reacting at 175° C., monitoring the change of acid value, and obtaining a first mixture with an acid value of 130 mgKOH / g;

[0048] S2, adding the polyol to the first mixture, raising the temperature to 205° C. for reaction, monitoring the change in acid value, and obtaining a second mixture with an acid value of 10 mgKOH / g;

[0049] S3, extracting xylene from the second mixture, adding propylene glycol butyl ether, and obtaining a third mixture with a solid content of 70 wt%;

[0050] S4, mixing acrylic monomers uniformly, adding 2 wt % of an initiator accounting for the total amount of acrylic monomers and mixing uniformly to obtain a fourth mixture;

[0051] S5, adding the fourth mixture dropwise to the third mixture within 3 hours, adding a neutralizer to adjust the pH to 7.0, and then adding water for emulsification to obtain a cardanol-modified aqueous emulsion with a solid content of 43 wt % and a viscosity of 3000 cP at 25° C.

[0052] The mass ratio of the fourth mixture to the third mixture is 3:7.

[0053] The catalyst was added in an amount of 0.5 wt % in the first mixture, and xylene was added in an amount of 4 wt % in the first mixture.

[0054] Example 2

[0055] The specific implementation is the same as that of Example 1; the difference is that the molar ratio of cardanol, polyacid and polyol in Example 2 is 1:1:1.02.

[0056] Example 3

[0057] The specific implementation is the same as that of Example 1; the difference is that the molar ratio of cardanol, polyacid and polyol in Example 3 is 0.8:1:1.02.

[0058] Comparative Example 1

[0059] The specific implementation is the same as Example 1; the difference is that the acrylic monomers in Comparative Example 1 are styrene, butyl acrylate, methyl methacrylate, and methacrylic acid in a mass ratio of 2:2:5:0.1.

[0060] Performance Testing Methods

[0061] The cardanol modified aqueous emulsion prepared in the embodiment and comparative example was added to color paste, additives, drying agent, etc. and dispersed evenly, with a fineness of ≤20um and a spray thickness of 30-40um. The paint film was oxidized and dried for one week before performance testing was performed. The test data are listed in Table 1.

[0062] Performance test data

[0063] Table 1

[0064]

Claims

1. A cardanol-modified aqueous emulsion, characterized in that: The preparation raw materials include: cardanol, polyol, polyacid, acrylic monomer, catalyst, neutralizer, initiator, organic solvent and water; the molar ratio of the cardanol, polyacid and polyol is (0.8-1.5):1:(1.02-1.05).

2. The cardanol-modified aqueous emulsion according to claim 1, characterized in that: The molar ratio of the cardanol, the polyacid and the polyol is (0.8-1.3):1:(1.02-1.05).

3. The cardanol-modified aqueous emulsion according to claim 2, characterized in that: The organic solvent includes xylene and propylene glycol butyl ether.

4. The cardanol-modified aqueous emulsion according to claim 3, characterized in that: The acrylic monomer includes at least one of styrene, butyl acrylate, methyl methacrylate and methacrylic acid.

5. The cardanol-modified aqueous emulsion according to claim 4, characterized in that: The acrylic monomers include styrene, butyl acrylate, methyl methacrylate, and methacrylic acid, and the weight ratio of styrene, butyl acrylate, methyl methacrylate, and methacrylic acid is 2:(1-3):(5-6): (0.2-0.5)。 6. The cardanol-modified aqueous emulsion according to claim 5, characterized in that: The catalyst comprises at least one of triethylamine, triethanolamine, diethanolamine, m-xylylenediamine, diaminophenylmethane, 2,4,6-tris(dimethylaminomethyl)phenol, tetraethylammonium bromide and tetrabutylammonium chloride.

7. A method for preparing the cardanol-modified aqueous emulsion according to any one of claims 3 to 6, characterized in that: The following steps are involved: S1, mixing cardanol, polyacid, catalyst and xylene to react to obtain a first mixture; S2, adding a polyol to the first mixture to react to obtain a second mixture; S3, extracting xylene from the second mixture and adding propylene glycol butyl ether to obtain a third mixture; S4, mixing acrylic monomers uniformly, adding initiators and mixing uniformly, to obtain a fourth mixture; S5, adding the fourth mixture dropwise to the third mixture, and then sequentially adding a neutralizer and water, and emulsifying to obtain a cardanol-modified aqueous emulsion.

8. The method for preparing the cardanol-modified aqueous emulsion according to claim 7, characterized in that: The reaction temperature in step S1 is 160-190°C, and the reaction temperature in step S2 is 190-220°C.

9. The method for preparing the cardanol-modified aqueous emulsion according to claim 8, characterized in that: The acid value of the first mixture is not higher than 130 mgKOH / g, and the acid value of the second mixture is not higher than 10 mgKOH / g.

10. The method for preparing the cardanol-modified aqueous emulsion according to claim 9, characterized in that: The dripping time in step S5 is 2-5 hours.

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