Preparation method of deionized water-based epoxy ester dispersion for single-component industrial anticorrosive paint

Abstract

The invention relates to the technical field of coatings, and discloses a preparation method of a deionized water-based epoxy ester dispersion for a single-component industrial anticorrosive coating, which comprises the following steps: preparing vegetable fatty acid, rosin, E-14 epoxy resin, ethylene glycol monobutyl ether, acrylic acid and ester monomers and deionized water, preparing an epoxy ester intermediate from the vegetable fatty acid, the rosin and the E-14 epoxy resin, and preparing the epoxy ester intermediate from the deionized water; grafting an acrylate monomer under the action of an initiator, and neutralizing to obtain a to-be-emulsified substance; according to the preparation method, by adjusting the proportion of the epoxy ester intermediate and the acrylics in the raw materials, to-be-emulsified substances with different oil degrees and different molecular weights can be prepared, the performance requirements can be better adjusted, and through matching of different raw material monomers, the high-performance emulsion can be prepared. The balance of rigidity and toughness of the resin can be adjusted, and finally, the deionized water-based epoxy ester dispersion has the advantages of excellent pigment and filler wettability, excellent deionized water resistance and high gloss.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to a method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating. Background Art

[0002] The anti-corrosion mechanism of anti-corrosion coatings is to form a barrier coating on the metal surface, preventing deionized water and oxygen from coming into contact with the metal surface. Anti-corrosion coatings are one of the most widely used and important industrial coatings in the world.

[0003] Deionized water-based lightweight anti-corrosion coatings made from alkyd resins offer excellent pigment and filler wettability, deionized water resistance, and high gloss. However, their slow drying time is a major drawback, and the presence of ester groups prevents their salt spray performance from meeting the increasingly stringent market requirements. Epoxy resin-based anti-corrosion coatings also offer excellent salt spray performance, but require an epoxy curing agent, which increases the construction process and is inconvenient. Epoxy ester resins, which combine the strengths of both, have attracted considerable attention since the 1990s. With the introduction of the national oil-to-deionized water strategy, deionized water-based epoxy ester resins have emerged. In response to increasingly stringent environmental protection requirements, we have developed deionized water-based epoxy ester dispersions suitable for industrial anti-corrosion coatings to address the market demand for environmentally friendly, medium-duty anti-corrosion coatings. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a method for preparing a deionized water-based epoxy ester dispersion for a one-component industrial anti-corrosion coating, which has the advantages of excellent wettability of pigments and fillers, outstanding resistance to deionized water, and high gloss. It solves the problems of slow drying and insufficient salt spray performance of alkyd resin deionized water-based light anti-corrosion coatings in existing coatings, as well as the complex construction of epoxy resin anti-corrosion coatings.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating, comprising the following preparation steps: Step 1: Prepare raw materials: prepare vegetable fatty acid, rosin, E-14 epoxy resin, ethylene glycol monobutyl ether, acrylic acid and ester monomers, and deionized water; Step 2, preparation of a water-based epoxy ester intermediate: adding vegetable fatty acid, E-14 epoxy resin and rosin into a reaction flask, setting the reaction conditions and reacting until the acid value of the reaction solution is less than 5, then lowering the reaction temperature and adding ethylene glycol monobutyl ether to obtain a water-based epoxy ester intermediate; Step 3, preparation of water-based epoxy ester emulsion: add the water-based epoxy ester intermediate into the reaction bottle, prepare the acrylic acid drop material, stir evenly, raise the temperature to 135-140 ° C, add the acrylic acid monomer dropwise at a uniform rate within 3-3.15 hours of the reaction, add the initiator after the addition is complete, keep the temperature for 1.0-1.1 hours, then add the initiator again, continue to keep the temperature for 2.95-3.05 hours, reduce the temperature to 60-70 ° C, and perform neutralization treatment to obtain the water-based epoxy ester emulsion; Step 4. Preparation of deionized aqueous epoxy ester dispersion: Transfer the aqueous epoxy ester emulsion to a high-speed dispersing tank, add hot deionized water accounting for 20% of the volume of the emulsion, start stirring, and gradually increase the speed from 5-10 r / min to 1100-1200 r / min. The dispersion time is 15-18 minutes. After the dispersion is completed, the remaining deionized water is added dropwise to prepare the deionized aqueous epoxy ester dispersion.

[0006] Preferably, the raw materials and their weight percentages include: 10% to 18% vegetable fatty acids; 0.2% to 0.5% rosin; 10% to 18% E-14 epoxy resin; 4% to 6% ethylene glycol monobutyl ether; 11% to 15% acrylic acid and ester monomers; and 40% to 50% deionized water.

[0007] Preferably, the plant fatty acid is composed of one or more of soybean oil acid, linoleic acid, tall oil acid, and deionized ricinoleic acid.

[0008] Preferably, the acrylic acid and ester monomers are composed of one or more of butyl acrylate, methyl methacrylate, styrene, acrylic acid, tert-butyl acrylate, lauryl acrylate, and isooctyl acrylate.

[0009] Preferably, the epoxy equivalent of the E-14 epoxy resin is ≤750.

[0010] Preferably, the reaction conditions in step 1 are: raising the temperature to 220-230° C. for reaction, and controlling the reaction time to be more than 4 hours.

[0011] Preferably, after the acid value of the reaction solution in step 1 is less than 5, the temperature is lowered to 145-150°C.

[0012] Preferably, in step 2, the ratio of the aqueous epoxy ester intermediate to the solid content of the dispersion is 30% to 45%.

[0013] Preferably, the temperature of the hot deionized water in step 3 is 60-70°C.

[0014] Preferably, the components of the aqueous epoxy ester emulsion in step 3 and their weight ratios to the aqueous epoxy ester intermediate are: 30% to 45% vegetable fatty acid; 3% to 8% rosin; 30% to 45% E-14 epoxy resin; and 10% to 15% ethylene glycol monobutyl ether.

[0015] Compared with the prior art, the present invention provides a method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating, which has the following beneficial effects: 1. The deionized water-based epoxy ester dispersion of the present invention is prepared by esterifying plant fatty acids, rosin, and E-14 epoxy resin at high temperature, cooling and diluting after the acid value meets the requirements, to obtain a water-based epoxy ester intermediate. The raw materials used in the water-based epoxy ester intermediate are mostly derived from organisms and are renewable resources, meeting the standards of bio-based materials. The introduced rosin not only has conjugated double bonds and strong activity, providing a basis for subsequent grafting of acrylate monomers, but also has its own unique tricyclic diterpene structure, which provides rigidity and dryness.

[0016] 2. The present invention can prepare emulsions with different oiliness and molecular weight by adjusting the ratio of epoxy ester intermediates and acrylates in the raw materials, which can better adjust performance requirements. Moreover, by matching different raw monomers, the balance between resin rigidity and toughness can be adjusted, ultimately making the deionized water-based epoxy ester dispersion have the advantages of excellent pigment and filler wettability, outstanding deionized water resistance and high gloss. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart was prepared for the present invention. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] See also Figure 1 A method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating comprises the following steps: Step 1: Prepare raw materials: prepare vegetable fatty acid, rosin, E-14 epoxy resin, ethylene glycol monobutyl ether, acrylic acid and ester monomers, and deionized water; Step 2, preparation of a water-based epoxy ester intermediate: adding vegetable fatty acid, E-14 epoxy resin and rosin into a reaction flask, setting the reaction conditions and reacting until the acid value of the reaction solution is less than 5, then lowering the reaction temperature and adding ethylene glycol monobutyl ether to obtain a water-based epoxy ester intermediate; The advantages are: plant fatty acids, rosin, and E-14 epoxy resin are first esterified at high temperature, and then cooled and diluted after the acid value meets the requirements to obtain a water-based epoxy ester intermediate. The raw materials used in the water-based epoxy ester intermediate are mostly derived from organisms and are renewable resources, meeting the standards of bio-based materials. At the same time, the introduced rosin not only has conjugated double bonds and strong activity, providing a basis for the subsequent grafting of acrylate monomers, but also has its own unique tricyclic diterpene structure, which provides rigidity and dryness. Step 3, preparation of water-based epoxy ester emulsion: add the water-based epoxy ester intermediate into the reaction bottle, prepare the acrylic acid drop material, stir evenly, raise the temperature to 135-140 ° C, add the acrylic acid monomer dropwise at a uniform rate within 3-3.15 hours of the reaction, add the initiator after the addition is complete, keep the temperature for 1.0-1.1 hours, then add the initiator again, continue to keep the temperature for 2.95-3.05 hours, reduce the temperature to 60-70 ° C, and perform neutralization treatment to obtain the water-based epoxy ester emulsion; Step 4. Preparation of deionized aqueous epoxy ester dispersion: Transfer the aqueous epoxy ester emulsion to a high-speed dispersing tank, add hot deionized water accounting for 20% of the volume of the emulsion, start stirring, and gradually increase the speed from 5-10 r / min to 1100-1200 r / min. The dispersion time is 15-18 minutes. After the dispersion is completed, the remaining deionized water is added dropwise to prepare the deionized aqueous epoxy ester dispersion.

[0020] The advantages are: by adjusting the ratio of epoxy ester intermediates and acrylates in the raw materials, emulsions with different oiliness and different molecular weights can be prepared, which can better adjust performance requirements. Moreover, by matching different raw monomers, the balance between resin rigidity and toughness can be adjusted, so that the deionized water-based epoxy ester dispersion has the advantages of excellent pigment and filler wettability, outstanding deionized water resistance and high gloss. Finally, an industrial anti-corrosion varnish with VOC less than 10%, bio-based content greater than 20%, initial water resistance greater than 168 hours, and salt spray resistance greater than 300 hours is prepared.

[0021] In the preparation method of the present invention, a water-based epoxy ester intermediate is prepared using vegetable fatty acids, E-14 epoxy resin, and rosin as raw materials. The epoxy ester intermediate with a suitable molecular weight is obtained by adjusting the oil content. Acrylic ester monomers are subjected to solvent polymerization to make the dispersion water-based and also increase the molecular weight of the final emulsion. The epoxy ester dispersion obtained by this method not only has a suitable oil content, can better wet pigments and fillers, and has excellent gloss and fullness, but also has excellent drying properties due to the modification of the acrylic acid portion and the large molecular weight of the bulk polymerization. At the same time, the main chain of the epoxy resin component has good stability, thereby significantly improving the salt spray performance.

[0022] Specifically, taking the total mass of the single-component water-based epoxy ester dispersion used in the field of industrial corrosion protection as 100%, the raw materials and their weight percentages include: 10% to 18% vegetable fatty acids; 0.2% to 0.5% rosin; 10% to 18% E-14 epoxy resin; 4% to 6% ethylene glycol monobutyl ether; 11% to 15% acrylic acid and ester monomers; and 40% to 50% deionized water.

[0023] Specifically, the plant fatty acid is composed of one or more of soybean oil acid, linoleic acid, tall oil acid, and deionized ricinoleic acid (plant fatty acids include but are not limited to soybean oil acid, linoleic acid, tall oil acid, and dehydrated ricinoleic acid).

[0024] Specifically, the acrylic acid and ester monomers are composed of one or more of butyl acrylate, methyl methacrylate, styrene, acrylic acid, tert-butyl acrylate, lauryl acrylate, and isooctyl acrylate.

[0025] Specifically, the epoxy equivalent weight of the E-14 epoxy resin is ≤750.

[0026] Specifically, the reaction conditions in step 1 are: raising the temperature to 220-230° C. for reaction, and controlling the reaction time to be more than 4 hours.

[0027] Specifically, after the acid value of the reaction solution in step 1 is less than 5, the temperature is lowered to 145-150°C.

[0028] Specifically, in step 2, the ratio of the water-based epoxy ester intermediate to the solid content of the dispersion is 30% to 45%.

[0029] Specifically, the temperature of the hot deionized water in step 3 is 60-70°C.

[0030] Specifically, the components of the water-based epoxy ester emulsion in step 3 and their weight ratios to the water-based epoxy ester intermediate are: 30% to 45% of vegetable fatty acid; 3% to 8% of rosin; 30% to 45% of E-14 epoxy resin; and 10% to 15% of ethylene glycol monobutyl ether.

[0031] Therefore, the above-mentioned one-component aqueous epoxy ester dispersion for use in the field of industrial corrosion protection is obtained by the preparation method of the present invention. In its preparation process, plant fatty acid, E-14 epoxy resin, and rosin are put into a reaction bottle, heated to 220-130°C and reacted for more than 4 hours until the acid value is less than 5, then cooled to 150°C, and ethylene glycol monobutyl ether is added for dilution to obtain an epoxy ester intermediate. The epoxy ester intermediate is put into the reaction bottle, and then the acrylic ester addition material is prepared. After the reactor is heated to 135-140°C, the monomer is uniformly added dropwise within about 3 hours. After the addition is completed, the initiator is added, and the mixture is kept warm for 1 hour. Then, the initiator is added and the mixture is kept warm for 3 hours. After the insulation is completed, the temperature is lowered and the neutralizer is added to obtain an emulsion. When the temperature of the emulsion is greater than 100°C and less than 120°C, the emulsion is transferred to a high-speed dispersion tank. After the temperature drops below 100°C, 20% hot water is added, stirring is slowly started, and the speed is gradually increased to 1200r / min. After dispersing for 15 minutes, when the resin is dispersed and there is no floating water on the liquid surface, the remaining water is added dropwise until the solid content is reduced to 45%, the temperature is lowered and the material is discharged to obtain an epoxy ester dispersion. The experiment verified that the water-based epoxy ester dispersion in the field of single-component industrial anti-corrosion can meet the needs of industrial anti-corrosion coatings.

[0032] The following examples are based on the raw materials used in the present invention and their respective weight percentage ranges, as well as the preparation process of the present invention. The single-component aqueous epoxy ester dispersion products for use in the field of industrial corrosion protection were prepared under the conditions of the present invention and used in the examples for experimental verification. The relevant finished product performance test data are recorded, as shown in the following table: Test items Example 1 Example 2 Example 3 Example 4 Example 5 Types and proportions of plant fatty acids in alkyd intermediates Soybean oil Linoleic acid Tall oil acid Soybean oil acid: dehydrated ricinoleic acid = 10:1 Linoleic acid: dehydrated ricinoleic acid = 10:1 Mass ratio of epoxy ester intermediate to solid content 30% 30% —— 30% 30% varnish Paint making is normal Paint making is normal Gel during intermediate synthesis Paint making is normal Paint making is normal Paint film thickness 60μm 60μm —— 60μm 60μm Paint film is dry 24h 18h —— 22h 16h 60° gloss 85 90 —— 90 95 Initial water resistance >168h >168h —— >168h >168h Neutral salt spray 168h >300h —— 200h >300h Test items Example 6 Example 7 Example 8 Example 9 Example 10 Types and proportions of plant fatty acids in alkyd intermediates Tall oil acid: dehydrated ricinoleic acid = 10:1 Soybean oil acid: dehydrated ricinoleic acid = 10:1 Soybean oil acid: dehydrated ricinoleic acid = 10:1 Soybean oil acid: dehydrated ricinoleic acid = 8:1 Soybean oil acid: dehydrated ricinoleic acid = 5:1 Mass ratio of epoxy ester intermediate to solid content 30% 40% 50% 30% 30% varnish Paint making is normal Paint making is normal Gel during synthesis Gel during synthesis Gel during synthesis Paint film thickness 60μm 60μm —— —— —— Paint film is dry 20h 26h —— —— —— 60° gloss 90 90 —— —— —— Initial water resistance >168h >168h —— —— —— Neutral salt spray >300h >300h —— —— —— The data of the embodiments in the above table are summarized as follows: 1. Effect of plant fatty acid types on finished product performance Single fatty acids: Soybean oil acid in Example 1: neutral salt spray 168h, gloss 85; Linoleic acid in Example 2: salt spray >300h, gloss 90, actual drying time 18h; In Example 3, tall oil acid formed a gel during the synthesis process, indicating that it has high reactivity and that the process conditions need to be strictly controlled. Complex fatty acids: In Examples 4, 9, and 10, soybean oil acid and dehydrated ricinoleic acid are compounded; In Example 5, the higher the ratio of dehydrated ricinoleic acid in 10:1, the salt spray performance is significantly improved (>300h), and the gloss reaches 95; In Examples 9 and 10, the ratio of complex fatty acids in 8:1 / 5:1 was too high, resulting in the synthesis of gels, indicating that the compounding ratio needs to be balanced; In Examples 5 and 6, linoleic acid and dehydrated ricinoleic acid were compounded, wherein the salt spray time was >300h and the gloss was 90-95; The introduction of dehydrated ricinoleic acid can improve salt spray performance and gloss, but the compounding ratio needs to be controlled (recommended ≤10:1); 2. The influence of epoxy ester intermediate ratio on the performance of finished products 30% ratio (Examples 1-6): Synthetic stability, paint film curing time 16-24h, salt spray 168h to >300h, gloss 85-95, water resistance >168h; 40% ratio (Example 7): Salt spray is still >300h, but the actual drying time is extended to 26h, because the drying is slowed down due to the increase in molecular weight; 50% ratio (Examples 8-10): Gel formation occurred during the synthesis process, indicating that too high a ratio led to a sharp increase in system viscosity and a runaway reaction. The overall performance was optimal when the intermediate ratio was controlled between 30% and 40%. A ratio exceeding 40% was prone to gelation risk. 3. Compliance of key performance indicators of finished products Salt spray performance: The best are Examples 2, 5, 6, and 7 (>300h), meeting industrial anti-corrosion requirements (≥300h).

[0033] The tall oil acid system (Example 3) did not meet the standards due to synthesis failure; Water resistance: All successful examples are >168h, meeting the initial water resistance requirements; Drying time: The shortest is Example 2 (18 hours), and the longest is Example 7 (26 hours), both within a reasonable range (single-component coatings usually require 24 hours to dry); Gloss: The formulations containing dehydrated ricinoleic acid (Examples 5 and 6) have the highest gloss (95 and 90), indicating that it has a positive effect on the smoothness of the paint film; 4. Summary of Risk Points in Preparation Process Tall oil acid: High reaction activity requires strict control of temperature and catalyst dosage, otherwise it will easily gel (Example 3); Intermediate ratio: When it exceeds 40%, the stirring and heat dissipation conditions need to be optimized to avoid viscosity runaway (Examples 8-10); Initiator addition: Stepwise addition (primary initiator + supplementary initiator) can reduce residual monomers and improve conversion rate (refer to step 2 for process modification); Final conclusion: By optimizing the type of plant fatty acids (preferably linoleic acid or a compound system containing dehydrated ricinoleic acid), controlling the proportion of epoxy ester intermediates (30%-40%), and adopting a step-by-step initiation process, a water-based epoxy ester dispersion that meets industrial anti-corrosion requirements can be prepared. Its performance indicators are: neutral salt spray ≥300h; initial water resistance >168h; dry time ≤24h; gloss ≥90 (60°); VOC <10%, and biobased content >20%. This formula not only ensures anti-corrosion performance, but also takes into account environmental protection and construction convenience, making it suitable for steel structures, construction machinery and other fields. In summary, the water-based epoxy ester dispersion prepared by this method meets the performance requirements of one-component water-based industrial anti-corrosion coatings.

[0034] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating, characterized in that: The method comprises the following preparation steps: Step 1: Prepare raw materials: prepare vegetable fatty acid, rosin, E-14 epoxy resin, ethylene glycol monobutyl ether, acrylic acid and ester monomers, and deionized water; Step 2, preparation of a water-based epoxy ester intermediate: adding vegetable fatty acid, E-14 epoxy resin and rosin into a reaction flask, setting the reaction conditions and reacting until the acid value of the reaction solution is less than 5, then lowering the reaction temperature and adding ethylene glycol monobutyl ether to obtain a water-based epoxy ester intermediate; Step 3, preparation of water-based epoxy ester emulsion: add the water-based epoxy ester intermediate into the reaction bottle, prepare the acrylic acid drop material, stir evenly, raise the temperature to 135-140 ° C, add the acrylic acid monomer dropwise at a uniform rate within 3-3.15 hours of the reaction, add the initiator after the addition is complete, keep the temperature for 1.0-1.1 hours, then add the initiator again, continue to keep the temperature for 2.95-3.05 hours, reduce the temperature to 60-70 ° C, and perform neutralization treatment to obtain the water-based epoxy ester emulsion; Step 4. Preparation of deionized aqueous epoxy ester dispersion: Transfer the aqueous epoxy ester emulsion to a high-speed dispersing tank, add hot deionized water accounting for 20% of the volume of the emulsion, start stirring, and gradually increase the speed from 5-10 r / min to 1100-1200 r / min. The dispersion time is 15-18 minutes. After the dispersion is completed, the remaining deionized water is added dropwise to prepare the deionized aqueous epoxy ester dispersion.

2. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, wherein: The raw materials and their weight percentages include: 10% to 18% of vegetable fatty acids; 0.2% to 0.5% of rosin; 10% to 18% of E-14 epoxy resin; 4% to 6% of ethylene glycol monobutyl ether; 11% to 15% of acrylic acid and ester monomers; and 40% to 50% of deionized water.

3. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: The plant fatty acid is composed of one or more of soybean oil acid, linoleic acid, tall oil acid, and deionized ricinoleic acid.

4. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, wherein: The acrylic acid and ester monomers are composed of one or more of butyl acrylate, methyl methacrylate, styrene, acrylic acid, tert-butyl acrylate, lauryl acrylate, and isooctyl acrylate.

5. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, wherein: The epoxy equivalent of the E-14 epoxy resin is ≤750.

6. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: The reaction conditions in step 1 are: raising the temperature to 220-230° C. for reaction, and controlling the reaction time to be more than 4 hours.

7. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: After the acid value of the reaction solution in step 1 is less than 5, the temperature is lowered to 145-150°C.

8. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: In the step 2, the water-based epoxy ester intermediate accounts for 30% to 45% of the solid content of the dispersion.

9. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: The temperature of the hot deionized water in step 3 is 60-70°C.

10. The method for preparing a deionized aqueous epoxy ester dispersion for a one-component industrial anticorrosive coating according to claim 1, characterized in that: The components of the aqueous epoxy ester emulsion in step 3 and their weight ratios to the aqueous epoxy ester intermediate are: 30% to 45% of vegetable fatty acid; 3% to 8% of rosin; 30% to 45% of E-14 epoxy resin; and 10% to 15% of ethylene glycol monobutyl ether.

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