Preparation process and application of ethylene acrylic acid emulsion

Abstract

The application provides a preparation process of an ethylene acrylic acid emulsion, 40-50 parts of polyethylene wax is added into 80-100 parts of deionized water, heated to 50-80 DEG C, after the polyethylene wax is melted and the water is layered, 0.5-1 parts of a surfactant, 0.5-0.8 parts of an initiator are added, and the temperature is kept at 50-80 DEG C; 15 parts of an acrylic acid monomer is slowly added dropwise, and the solution changes from colorless and transparent to slightly milky white; after the dropwise addition is completed, 1-2 parts of a buffer, 1-2 parts of a stabilizer, 0.5-1 parts of ammonia water are added, and then appropriate 50% NaOH is added to adjust the pH to 7-8, and a semi-transparent white ethylene acrylic acid emulsion is obtained. The advantage lies in that the solution grafting method is used, the short-chain polyethylene wax is introduced in the polymerization process of the acrylic acid monomer, the ethylene chain is provided, the addition of the ethylene chain increases the functionality of the acrylic resin, and the prepared ethylene acrylic acid emulsion has the advantages of acid and alkali resistance and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a preparation process and application of ethylene acrylic emulsion. BACKGROUND

[0002] With the continuous improvement of the national economy, people's demand for green and environmental protection is also getting higher and higher. Among them, industrial coatings have been rapidly developing in the direction of environmental protection and pollution-free. Water-based acrylic coating has become the only choice for environmental protection coating because it does not contain organic solvents, is green, healthy and environmentally friendly.

[0003] Water-based acrylic coating can not only be used for coating of equipment, instruments, machinery and pipelines, but also for coating of wood, glass and even electronic materials. It is easy to operate, has good gloss and excellent weather resistance.

[0004] In the prior art, CN 103289006 A discloses a water-based acrylic resin and a preparation method thereof. The water-based acrylic resin comprises 30-40 parts of methyl methacrylate, 5-8 parts of acrylic acid, 10-15 parts of hydroxyethyl methacrylate, 3-5 parts of styrene, 3-5 parts of dimethylbenzene, 0.3-0.5 parts of initiator and 0.5-0.8 parts of crosslinking agent. During preparation, acrylic acid, styrene and initiator are added to a reaction container, and then methyl methacrylate, dimethylbenzene and methylaziridine are added after stirring. The coating film has good hardness, water resistance and weather resistance, and can meet the requirements of ordinary industrial paint. The disadvantage is that the synthesized acrylic resin has poor corrosion resistance, and the ethylene acrylic acid has good corrosion resistance, which is not suitable for metal corrosion prevention.

[0005] In view of this, the present inventors have conducted in-depth research on the above problems, and thus the present application is produced. SUMMARY

[0006] The present application solves the technical problem of poor corrosion resistance of the coating prepared from the existing acrylic resin, and provides a preparation process and application of ethylene acrylic emulsion.

[0007] The present application is implemented as follows: a preparation process of ethylene acrylic emulsion, comprising the following steps:

[0008] Step one: 40-50 parts of polyethylene wax are added to 80-100 parts of deionized water, heated to 50-80℃, and after the polyethylene wax is melted and the water is layered, 0.5-1 parts of surfactant and 0.5-0.8 parts of initiator are added to keep the temperature at 50-80℃;

[0009] Step two: start slowly adding 15 parts of acrylic monomer, and the solution changes from colorless and transparent to light milky white;

[0010] Step 3: After the addition is complete, add 1-2 parts buffer, 1-2 parts stabilizer, 0.5-1 part ammonia, and then add an appropriate amount of 45-55% NaOH to adjust the pH to 7-8, thus obtaining a semi-transparent white ethylene acrylic emulsion.

[0011] Furthermore, the molecular weight of the polyethylene wax is 800-1000.

[0012] Furthermore, the surfactant is either sodium dodecyl sulfate or sodium dodecyl sulfonate.

[0013] Furthermore, the initiator is any one of potassium persulfate, ammonium persulfate, and sodium persulfate.

[0014] Furthermore, the buffer is any one of sodium bicarbonate, potassium dihydrogen phosphate, and sodium acetate.

[0015] Furthermore, the stabilizer is polyvinyl alcohol.

[0016] Furthermore, in step two, the acrylic monomer is added dropwise over 20 minutes.

[0017] On the other hand, an application of an ethylene-acrylic acid emulsion is described, in which the aforementioned ethylene-acrylic acid emulsion is used to prepare a zinc-plated anti-corrosion coating.

[0018] On the other hand, an application of an ethylene-acrylic acid emulsion is described, in which the aforementioned ethylene-acrylic acid emulsion is used as a hot-dip galvanizing sealant.

[0019] The advantages of this invention are:

[0020] 1. This invention introduces short-chain polyethylene wax into the polymerization process of acrylic monomers through solution grafting, providing ethylene chains. The addition of ethylene chains increases the functionality of acrylic resin. The coating formulated from the polymerized ethylene-acrylic emulsion has the advantages of acid and alkali resistance and corrosion resistance, and can be used as an anti-corrosion coating for metals. After use, the neutral salt spray resistance of metals reaches 1500h.

[0021] 2. In the preparation process of the present invention, after the polyethylene wax is emulsified, it reacts directly with the acrylic acid monomer in water to generate an ethylene acrylic acid emulsion with a high grafting rate; the reaction can be carried out without sealing conditions and pressure, and the equipment requirements are low; and there is no need to introduce ethylene gas, so the process is simple and safe.

[0022] 3. The ethylene-acrylic acid emulsion of the present invention can be used as a hot-dip galvanizing sealant. Since the ethylene-acrylic acid emulsion has high corrosion resistance, its use as a sealant can eliminate the need for subsequent passivation processes.

Detailed Implementation Methods

[0023] All other embodiments obtained by those of ordinary skill in the art without creative work based on the embodiments of the present application fall within the scope of protection of the present application.

[0024] Embodiment one

[0025] The embodiment provides a preparation process of ethylene acrylic acid emulsion, and comprises the following steps:

[0026] Step one: 40-50 parts of polyethylene wax is added into 80-100 parts of deionized water, and heated to 50-80 DEG C; after the polyethylene wax is melted and the water is layered, 0.5-1 parts of surfactant and 0.5-0.8 parts of initiator are added, and the temperature is kept at 50-80 DEG C;

[0027] Step two: 15 parts of acrylic acid monomer is slowly added, and the acrylic acid monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white;

[0028] Step three: after the dropwise adding is completed, 1-2 parts of buffer, 1-2 parts of stabilizer, 0.5-1 parts of ammonia water, and appropriate amount of 45-55% NaOH are added to adjust the pH to 7-8, and a semi-transparent white ethylene acrylic acid emulsion is obtained.

[0029] In the embodiment, the molecular weight of the polyethylene wax is 800-1000. The polyethylene wax is purchased from Rushan Beihua New Material Science and Technology Co., Ltd. Low molecular weight is beneficial to high grafting rate of acrylic acid and emulsification.

[0030] In the embodiment, the surfactant is any one of sodium dodecyl sulfate or sodium dodecyl sulfonate.

[0031] In the embodiment, the initiator is any one of potassium persulfate, ammonium persulfate and sodium persulfate. The initiator enables the grafting reaction of polyethylene wax and acrylic acid monomer to be carried out.

[0032] In the embodiment, the buffer is any one of sodium bicarbonate, potassium dihydrogen phosphate and sodium acetate. The buffer is used for adjusting the reaction equilibrium.

[0033] In the embodiment, the stabilizer is polyvinyl alcohol.

[0034] The ethylene acrylic acid emulsion prepared in the embodiment has at least the following beneficial effects:

[0035] 1. In the preparation process of the ethylene acrylic acid emulsion, the polyethylene wax is directly reacted with the acrylic acid monomer in water after being emulsified to generate the ethylene acrylic acid emulsion, the grafting rate is high, the reaction can be carried out without pressure, the requirement for equipment is low, and the process is simple and safe without the need of introducing ethylene gas.

[0036] 2、The preparation process uses an emulsion polymerization method, and the directly synthesized ethylene acrylic acid emulsion has high corrosion resistance, and the ethylene acrylic acid emulsion can be used as a metal anticorrosive coating. The semi-transparent white ethylene acrylic acid emulsion is subjected to salt spray test after being soaked in metal for 3-4 seconds and then being dried, and the time for white rust and red rust to appear is as high as about 1500 hours.

[0037] A plurality of experiments are performed using the preparation process of the ethylene acrylic acid emulsion of the present embodiment, and the following selected several test groups and comparison groups are used to further illustrate the beneficial effects of the preparation process of the ethylene acrylic acid emulsion described in the present embodiment.

[0038] Test Group One

[0039] Step One: 40 parts of polyethylene wax with a molecular weight of 800-1000 are added to 80 parts of deionized water, heated to 50-80℃, and after the polyethylene wax is melted and the water is layered, 0.5 parts of a surfactant and 0.5 parts of a per-initiator are added, and the temperature is maintained at 50-80℃; the surfactant is sodium dodecyl sulfate, and the initiator is potassium persulfate.

[0040] Step Two: Start slowly adding 15 parts of acrylic acid monomer, and the acrylic acid monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white.

[0041] Step Three: After the dropwise addition is completed, 1 part of a buffer and 1 part of a stabilizer are added, 0.5 parts of ammonia water are added, and then an appropriate amount of 50% NaOH is added to adjust the pH to 7-8, thereby obtaining a semi-transparent white ethylene acrylic acid emulsion. The buffer is sodium bicarbonate.

[0042] Step Four: The ethylene acrylic acid emulsion is subjected to salt spray test after being soaked in metal for 3-4 seconds and then being dried, and the time for white rust and red rust to appear on the metal is observed.

[0043] Test Group Two

[0044] Step One: 45 parts of polyethylene wax with a molecular weight of 800-1000 are added to 90 parts of deionized water, heated to 50-80℃, and after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant and 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80℃; the surfactant is sodium dodecyl sulfate, and the initiator is potassium persulfate.

[0045] Step Two: Start slowly adding 15 parts of acrylic acid monomer, and the acrylic acid monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white.

[0046] Step three: after the dropwise addition is completed, 1.5 parts of a buffer, 1.5 parts of a stabilizer, 0.75 parts of ammonia water are added, and then an appropriate amount of 50% NaOH is added to adjust the pH to 7-8, thereby obtaining the semi-transparent white ethylene acrylic acid emulsion. The buffer is sodium bicarbonate.

[0047] Step four: the ethylene acrylic acid emulsion is soaked with metal for 3-4 seconds, then dried and subjected to a salt spray test, and the time length for the metal to appear white rust and red rust is observed.

[0048] Test group three

[0049] Step one: 50 parts of polyethylene wax with a molecular weight of 800-1000 are added to 100 parts of deionized water, heated to 50-80°C, and after the polyethylene wax is melted and the water is layered, 1 part of a surfactant and 0.8 parts of a per-initiator are added, and the temperature is maintained at 50-80°C; the surfactant is sodium dodecyl sulfate, and the initiator is potassium persulfate.

[0050] Step two: start slowly adding 15 parts of acrylic acid monomer, and the acrylic acid monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white.

[0051] Step three: after the dropwise addition is completed, 2 parts of a buffer, 2 parts of a stabilizer, 1 part of ammonia water are added, and then an appropriate amount of 50% NaOH is added to adjust the pH to 7-8, thereby obtaining the semi-transparent white ethylene acrylic acid emulsion. The buffer is sodium bicarbonate.

[0052] Step four: the ethylene acrylic acid emulsion is soaked with metal for 3-4 seconds, then dried and subjected to a salt spray test, and the time length for the metal to appear white rust and red rust is observed.

[0053] Test group four

[0054] Step one: 45 parts of polyethylene wax with a molecular weight of 800-1000 are added to 90 parts of deionized water, heated to 50-80°C, and after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant and 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80°C; the surfactant is sodium dodecyl sulfate, and the initiator is ammonium persulfate.

[0055] Step two: start slowly adding 15 parts of acrylic acid monomer, and the acrylic acid monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white.

[0056] Step three: after the dropwise addition is completed, 1.5 parts of a buffer, 1.5 parts of a stabilizer, 0.75 parts of ammonia water are added, and then an appropriate amount of 50% NaOH is added to adjust the pH to 7-8, thereby obtaining the semi-transparent white ethylene acrylic acid emulsion. The buffer is potassium dihydrogen phosphate.

[0057] Step four: the ethylene acrylic acid emulsion is soaked with metal for 3-4 seconds, then dried and subjected to salt spray test, and the time length for the metal to appear white rust and red rust is observed.

[0058] Test group five

[0059] Step one: 45 parts of polyethylene wax with a molecular weight of 800-1000 are added to 90 parts of deionized water, heated to 50-80°C, and after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant and 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80°C; the surfactant is sodium dodecyl sulfonate, and the initiator is potassium persulfate.

[0060] Step two: start slowly adding 15 parts of acrylic monomer, and the acrylic monomer is added dropwise for 20 minutes; the solution changes from white and transparent to slightly milky white.

[0061] Step three: after the dropwise addition is completed, 1.5 parts of a buffer and 1.5 parts of a stabilizer are added, 0.75 parts of ammonia water is added, and then an appropriate amount of 50% NaOH is added to adjust the pH to 7-8, thereby obtaining a semi-transparent white ethylene acrylic acid emulsion. The buffer is sodium acetate.

[0062] Step four: the ethylene acrylic acid emulsion is soaked with metal for 3-4 seconds, then dried and subjected to salt spray test, and the time length for the metal to appear white rust and red rust is observed.

[0063] Comparison group one

[0064] Step one: 45 parts of polyethylene wax with a molecular weight of 1000-8000 are added to 90 parts of deionized water, heated to 50-80°C, and after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant and 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80°C; the surfactant is sodium dodecyl sulfonate, and the initiator is potassium persulfate.

[0065] Step two: start slowly adding 15 parts of acrylic monomer, and the acrylic monomer is added dropwise for 20 minutes; the white granular suspension is separated, and it is found that it is not soluble in water and cannot be tested.

[0066] Comparison group two

[0067] Step one: 45 parts of polyethylene wax with a molecular weight of 800-1000 are added to 90 parts of deionized water, heated to 50-80°C, and after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant and 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80°C; the surfactant is OP-10, and the initiator is potassium persulfate.

[0068] Step two: start slowly adding 15 parts of acrylic monomer, and the acrylic monomer is added dropwise for 20 minutes; the white granular suspension is separated, and it is found that it is not soluble in water and cannot be tested.

[0069] Comparative Group Three

[0070] Step One: 45 parts of polyethylene wax with a molecular weight of 800-1000 is added to 90 parts of deionized water, heated to 50-80℃, after the polyethylene wax is melted and the water is layered, 0.75 parts of a surfactant, 0.75 parts of a per-initiator are added, and the temperature is maintained at 50-80℃; the surfactant is sodium dodecyl sulfate, and the initiator is potassium persulfate.

[0071] Step Two: Start slowly adding 15 parts of acrylic monomer, and the acrylic monomer is added dropwise for 10 minutes; if the acrylic acid is added too fast, it will form a white waxy hard solid and the reaction cannot proceed.

[0072] Table 1: Composition comparison and experimental phenomena of each test group and comparative group

[0073]

[0074]

[0075] According to the experimental results in Table 1, the ethylene acrylic acid emulsion prepared by the preparation process of the present application has the advantages of acid and alkali resistance and corrosion resistance, and can be used as a metal anticorrosive coating, and the neutral salt spray test of the metal after use reaches 1500h.

[0076] 2. Compared with Comparative Group One, Comparative Group Two and the five test groups, it can be seen that only low molecular weight polyethylene wax can react with acrylic monomer to form ethylene acrylic acid emulsion, which is beneficial to high grafting rate of acrylic acid and emulsification. Moreover, there are specific requirements for the selection of surfactants, and OP-10 cannot be used as an emulsifier to dissolve ethylene acrylic acid in water.

[0077] 3. Compared with Comparative Group Three and the five test groups, it can be seen that the acrylic monomer should not be added too fast, otherwise it will form a white waxy hard solid and the reaction cannot proceed.

[0078] Example Two

[0079] The present embodiment provides an application of an ethylene acrylic acid emulsion. The ethylene acrylic acid emulsion described in Example One is used to prepare a galvanized anticorrosive coating. The galvanized anticorrosive coating of the present embodiment has a neutral salt spray test of the metal after use reaching 1500h, and has high corrosion resistance.

[0080] Example Three

[0081] The present embodiment provides an application of the ethylene acrylic acid emulsion. The ethylene acrylic acid emulsion described in the first embodiment is used for a hot galvanizing sealing agent. The galvanizing corrosion sealing agent of the present embodiment is used, and the neutral salt spray test of the metal after use reaches 1500h. Due to the high corrosion resistance, the subsequent passivation process can be omitted.

[0082] Although the specific embodiments of the present application are described above, those skilled in the art should understand that the specific embodiments described are only illustrative, and are not intended to limit the scope of the present application. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present application should be covered within the scope of the claims of the present application.

Claims

1. A preparation process for an ethylene-acrylic acid emulsion, characterized in that: Includes the following steps: Step 1: Add 40-50 parts of polyethylene wax to 80-100 parts of deionized water, heat to 50-80°C, and after the polyethylene wax melts and the water separates into layers, add 0.5-1 parts of surfactant and 0.5-0.8 parts of initiator, maintaining the temperature at 50-80°C; the polyethylene wax has a molecular weight of 800-1000; the surfactant is any one of sodium dodecyl sulfate or sodium dodecyl sulfonate. Step 2: Slowly add 15 parts of acrylic monomer, and the solution will change from colorless and transparent to slightly milky white; Step 3: After the addition is complete, add 1-2 parts buffer, 1-2 parts stabilizer, 0.5-1 part ammonia, and then add an appropriate amount of 45-55% NaOH to adjust the pH to 7-8, thus obtaining a translucent white ethylene acrylic emulsion; the stabilizer is polyvinyl alcohol.

2. The preparation process of the ethylene-acrylic acid emulsion as described in claim 1, characterized in that: The initiator is any one of potassium persulfate, ammonium persulfate, and sodium persulfate.

3. The preparation process of the ethylene-acrylic acid emulsion as described in claim 1, characterized in that: The buffer is any one of sodium bicarbonate, potassium dihydrogen phosphate, and sodium acetate.

4. The preparation process of the ethylene-acrylic acid emulsion as described in claim 1, characterized in that: In step two, the acrylic monomer is added dropwise over 20 minutes.

5. An application of an ethylene-acrylic acid emulsion, characterized in that: The ethylene-acrylic emulsion prepared by the preparation process of the ethylene-acrylic emulsion according to any one of claims 1-4 is used to prepare galvanized anti-corrosion coatings.

6. An application of an ethylene-acrylic acid emulsion, characterized in that: The ethylene-acrylic acid emulsion prepared by the preparation process of any one of claims 1-4 is used as a hot-dip galvanizing sealant.

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