Preparation process and application of low molecular weight polyethylene wax and acrylic acid synthetic polyethylene acrylic acid

Abstract

The application provides a preparation process of a low-molecular-weight polyethylene wax and acrylic acid synthetic polyethylene acrylic acid, 50-60 parts of polyethylene wax is added into 40-50 parts of butyl acetate, after stirring and dissolving, 0.1-0.2 parts of an initiator is added; 10 parts of an acrylic acid monomer is slowly dropped, the solution starts to turn white, after dropping, 0.1-0.2 parts of an initiator is added; the supernatant of the solution is filtered, the white precipitate in the lower layer is vacuum dried, and polyethylene acrylic acid powder is obtained. The advantage lies in that the low-molecular-weight polyethylene wax is used for grafting reaction with the acrylic acid, the polyethylene acrylic acid can be synthesized under simple environmental conditions, the reaction does not need high temperature and high pressure, the formula is simple, and the operation is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polymer synthesis and chemical coating technology, and particularly relates to a preparation process and application of low-molecular-weight polyethylene wax and acrylic acid for synthesizing polyethylene acrylic acid. BACKGROUND

[0002] Generally, polyethylene acrylic acid is a high-molecular polymer formed by polymerization of ethylene and acrylic acid. In the polymer, the ethylene part provides the hydrophobicity, ductility and weather resistance of the polyethylene acrylic acid, and the acrylic acid part brings polarity, adhesion and high hardness to the polymer molecule. The increase of the acrylic acid part increases the adhesion, polarity and hardness of the high-molecular polymer, reduces the melting point of the polymer, and increases the transparency and adhesion. The copolymer of ethylene acrylic acid is widely used, and is largely used in soft packaging, such as laminated tube, aseptic packaging, meat and cheese packaging, and protective metal coating, wire and cable, and powder coating. The aqueous dispersion of ethylene acrylic acid can be used as a glass adhesive, ink and paint formulation.

[0003] In the industrial synthesis of ethylene acrylic acid copolymer, ethylene gas and acrylic acid are often reacted at high temperature and high pressure by using an initiator. The reaction temperature is in the range of 300-500 DEG C, and the pressure range is generally between 10-20 MPa, which is very harsh. Due to the industrial complexity involved, the synthesis of ethylene acrylic acid copolymer is currently monopolized by foreign countries. Most of the polyethylene acrylic acid used in China is imported from foreign companies such as Bayer, Dow and BASF.

[0004] For example, the prior art CN102167783A discloses a method for functionalizing polyethylene wax, and the formula uses polyethylene wax with a molecular weight of 1000-8000, and the solvent used is petroleum ether. The disadvantages are that the molecular weight of the polyethylene wax used is too high, the grafting rate of the acrylic acid in the finally prepared product is too low, only 12.1%, the synthesized product (white solid PEW-g-AA) is not soluble in water, and the solvent used is flammable and explosive, which requires high safety factor, resulting in high hardware requirements for the reactor equipment.

[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] In order to overcome the weaknesses of the prior art, such as low grafting rate of ethylene acrylic acid, insolubility in water, and high safety factor and hardware equipment requirements in the preparation process, the present application provides a synthesis method for grafting acrylic acid on polyethylene wax, which does not require high temperature and high pressure, has a simple formula and is easy to operate. The generated polyethylene acrylic acid is soluble in water at room temperature under the action of a cosolvent, is suitable for metal coating, is used as a sealing agent for zinc-plated metal, and the neutral salt spray test time reaches 1520 h.

[0007] The application is implemented by a preparation process of low molecular weight polyethylene wax and acrylic acid for synthesizing polyethylene acrylic acid, comprising the following steps:

[0008] Step one: 50-60 parts of polyethylene wax is added into 40-50 parts of butyl acetate, after stirring and dissolving, 0.1-0.2 parts of initiator is added;

[0009] Step two: 10 parts of acrylic acid monomer is slowly dropped, the solution begins to turn white, after dropping, 0.1-0.2 parts of initiator is added; at this time, the white precipitate in the solution is polyethylene acrylic acid;

[0010] Step three: the supernatant of the solution is filtered, and the lower white precipitate is vacuum dried to obtain polyethylene acrylic acid powder.

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

[0012] Further, in step two, 10 parts of acrylic acid monomer is slowly dropped for 14-16 minutes.

[0013] Further, the initiator is any one of potassium persulfate or ammonium persulfate.

[0014] Further, it further comprises step four, 20-30g of polyethylene acrylic acid powder is taken, 200ml of water is added, heated to 80℃, and 2-3g of a cosolvent is added to obtain a polyethylene acrylic acid solution.

[0015] Further, the cosolvent is any one of sodium salicylate, p-aminobenzoic acid, nicotinamide, or acetamide.

[0016] Further, the grafting rate of the polyethylene acrylic acid powder is measured by the following method: the polyethylene acrylic acid powder is extracted with acetone for 20-24h, 0.5g is dissolved in hot xylene, then neutralized with sodium hydroxide-ethanol solution, using phenothalin as an indicator, and the excess alkali is titrated with hydrochloric acid, and finally the grafting rate is measured.

[0017] On the other hand, the application of low molecular weight polyethylene wax and acrylic acid for synthesizing polyethylene acrylic acid, the above-mentioned polyethylene acrylic acid solution is used for preparing a galvanized sealing agent.

[0018] On the other hand, the application of low molecular weight polyethylene wax and acrylic acid for synthesizing polyethylene acrylic acid, the above-mentioned polyethylene acrylic acid solution is used for preparing a coating.

[0019] The application has the following advantages:

[0020] 1. The low molecular weight polyethylene wax is grafted with acrylic acid to synthesize polyethylene acrylic acid under simple environmental conditions, the reaction does not require high temperature and high pressure, the formula is simple, and the operation is simple; the prepared polyethylene acrylic acid overcomes the harsh conditions that ethylene gas is introduced into an acrylic acid solution under high temperature and high pressure, and the operation is simple.

[0021] 2. The low molecular weight polyethylene wax greatly increases the grafting rate of acrylic acid; the selected cosolvent enables the polyethylene acrylic acid powder to be soluble in water at room temperature, and the polyethylene acrylic acid powder can be used to prepare a metal zinc plating sealing agent, the neutral salt spray test of the metal zinc plating sealing agent can reach about 1500 hours, which is much higher than that of the prior art, the metal sealing agent has good performance, and the polyethylene acrylic acid powder can also be used to prepare anticorrosive paint, and the paint has good corrosion resistance.

[0022] 3. Butyl acetate is used as a solvent for the grafting reaction in the grafting reaction process, the solvent is safe and non-toxic, and the solvent overcomes the defects that petroleum ether is flammable and explosive.

DETAILED DESCRIPTION

[0023] Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0024] Example 1

[0025] The embodiment provides a preparation process of polyethylene acrylic acid synthesized by low molecular weight polyethylene wax and acrylic acid, and the preparation process comprises the following steps.

[0026] Step 1: 50-60 parts of polyethylene wax are added into 40-50 parts of butyl acetate, and after stirring and dissolving, 0.1-0.2 parts of an initiator is added.

[0027] Step 2: 10 parts of acrylic acid monomer are slowly dropped, the solution begins to turn white, and after dropping is completed, 0.1-0.2 parts of an initiator is added again; at this time, the white precipitate in the solution is polyethylene acrylic acid; the second addition of the initiator is beneficial to the full reaction.

[0028] Step 3: The upper clear solution of the solution is filtered off, and white solid polyethylene acrylic acid is obtained by vacuum filtration with ethanol, and the polyethylene acrylic acid powder is obtained after drying.

[0029] Step 4: 20-30 g of polyethylene acrylic acid powder is taken, 200 ml of water is added, heated to 80 DEG C, and then 2-3 g of a cosolvent is added, to obtain a polyethylene acrylic acid solution.

[0030] In the embodiment, the molecular weight of the polyethylene wax is 800-1000, and the low molecular weight is beneficial to the high grafting rate of acrylic acid.

[0031] In step two of the present embodiment, 10 parts of acrylic monomer is slowly dropped in 14-16 minutes.

[0032] In the present embodiment, the initiator is any one of potassium persulfate or ammonium persulfate, which enables the grafting reaction of polyethylene wax and acrylic monomer to proceed.

[0033] The cosolvent is any one of sodium salicylate, p-aminobenzoic acid, nicotinamide, or acetamide. The cosolvent enables the polyethylene acrylic powder to be dissolved in water.

[0034] The method for measuring the grafting rate of acrylic acid also includes extracting the polyethylene acrylic powder with acetone for 20-24 hours, taking 0.5 g and dissolving in hot xylene, then adding sodium hydroxide-ethanol solution for neutralization, using phenothalin as the indicator, and titrating the excess alkali with hydrochloric acid. Finally, the grafting rate is measured.

[0035] A plurality of experiments are conducted using the preparation process of polyethylene acrylic acid synthesized by the low molecular weight polyethylene wax and acrylic acid of the present embodiment. The following selects several test groups and comparison groups to further illustrate the beneficial effects of the preparation process of polyethylene acrylic acid synthesized by the low molecular weight polyethylene wax and acrylic acid of the present embodiment.

[0036] Test Group One

[0037] 50 parts of polyethylene wax with a molecular weight of 800-1000 is added to 40 parts of butyl acetate, and after stirring and dissolving, 0.1 part of initiator is added. Then 10 parts of acrylic monomer is slowly dropped in 15 minutes, and the solution starts to turn white. After dropping, 0.1 part of initiator is added. At this time, the white precipitate in the solution is polyethylene acrylic acid. The supernatant of the solution is filtered off, and the white precipitate at the bottom is vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid is measured. Then 20-30 g of polyethylene acrylic acid powder is taken, 200 ml of water is added, heated to 80°C, and 2-3 g of cosolvent is added. The cosolvent is sodium salicylate. Thus, a polyethylene acrylic acid solution is obtained. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc-plated sealant, and the salt spray resistance time is measured.

[0038] Test Group Two

[0039] Add 55 parts of polyethylene wax with molecular weight of 800-1000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and the white precipitate in the lower layer is vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid is measured; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is sodium salicylate, to obtain a polyethylene acrylic acid solution. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0040] Test group three

[0041] Add 55 parts of polyethylene wax with molecular weight of 800-1000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and the white precipitate in the lower layer is vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid is measured; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is sodium salicylate, to obtain a polyethylene acrylic acid solution. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0042] Test group four

[0043] Add 55 parts of polyethylene wax with molecular weight of 800-1000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and the white precipitate in the lower layer is vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid is measured; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is sodium salicylate, to obtain a polyethylene acrylic acid solution. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0044] Test group five

[0045] Add 55 parts of polyethylene wax with molecular weight of 800-1000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and vacuum dry the white precipitate at the bottom to obtain polyethylene acrylic acid powder. At this time, measure the grafting rate of acrylic acid; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is nicotinamide. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0046] Comparison group one

[0047] Add 55 parts of polyethylene wax with molecular weight of 1000-8000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and vacuum dry the white precipitate at the bottom to obtain polyethylene acrylic acid powder. At this time, measure the grafting rate of acrylic acid; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is nicotinamide. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0048] Comparison group two

[0049] Add 55 parts of polyethylene wax with molecular weight of 1000-8000 into 45 parts of butyl acetate, after stirring and dissolving, add 0.15 parts of initiator; then slowly drop 10 parts of acrylic monomer in 15 minutes, the solution begins to turn white, after dropping, add 0.15 parts of initiator; at this time, the white precipitate in the solution is polyethylene acrylic acid; filter out the supernatant of the solution, and vacuum dry the white precipitate at the bottom to obtain polyethylene acrylic acid powder. At this time, measure the grafting rate of acrylic acid; take 20-30 g of polyethylene acrylic acid powder, add 200 ml of water, heat to 80℃, then add 2-3 g of cosolvent, and the cosolvent is nicotinamide. The polyethylene acrylic acid solution is used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time is measured.

[0050] Comparison group three

[0051] The 55 parts of polyethylene wax with a molecular weight of 800-1000 were added to 35 parts of butyl acetate, stirred and dissolved, and then 0.15 parts of an initiator was added; then 10 parts of acrylic monomer was slowly dropped in 15 minutes, the solution began to turn white, and after dropping was completed, 0.15 parts of an initiator was added; at this time, the white precipitate in the solution was polyethylene acrylic acid; the supernatant liquid of the solution was filtered off, and the lower layer white precipitate was vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid was measured; 20-30 g of polyethylene acrylic acid powder was taken, 200 ml of water was added, heated to 80°C, and then 2-3 g of a cosolvent was added, and the cosolvent was sodium salicylate; a polyethylene acrylic acid solution was obtained, which was used for neutral salt spray test of metal zinc plating sealant, and the salt spray resistance time was measured.

[0052] Comparison group four

[0053] The 55 parts of polyethylene wax with a molecular weight of 800-1000 were added to 45 parts of petroleum ether, stirred and dissolved, and then 0.15 parts of an initiator was added; then 10 parts of acrylic monomer was slowly dropped in 15 minutes, the solution began to turn white, and after dropping was completed, 0.15 parts of an initiator was added; at this time, the white precipitate in the solution was polyethylene acrylic acid; the supernatant liquid of the solution was filtered off, and the lower layer white precipitate was vacuum dried to obtain polyethylene acrylic acid powder. At this time, the grafting rate of acrylic acid was measured; the grafting rate obtained at this time was too low, which resulted in that the polyethylene acrylic acid powder could not be dissolved in water and could not be used for neutral salt spray test of metal zinc plating sealant.

[0054] Comparison group five

[0055] The 55 parts of polyethylene wax with a molecular weight of 800-1000 were added to 45 parts of butyl acetate, stirred and dissolved, and then 0.15 parts of an initiator was added; then 10 parts of acrylic monomer was quickly dropped in 7-8 minutes, the solution began to turn white, and after dropping was completed, 0.15 parts of an initiator was added; however, the acrylic acid was too fast to form a white waxy solid, and the reaction could not continue.

[0056] Table 1 Comparison of components and experimental phenomena of each test group and comparison group

[0057]

[0058]

[0059] According to the experimental results in Table 1, it can be seen that:

[0060] 1. Comparing groups one through three and the five experimental groups, it is evident that using low molecular weight polyethylene wax to graft acrylic acid significantly increases the grafting rate of acrylic acid. The resulting polyethylene-acrylic acid solution can withstand 1520 hours of neutral salt spray testing in the metal plating sealant, demonstrating good performance and corrosion resistance in the metal plating sealant. Polyethylene-acrylic acid produced using high molecular weight polyethylene wax is insoluble in water and cannot be used to prepare metal plating sealants. Insufficient polyethylene wax will generate excess polyacrylic acid impurities, forming a mixed powder that is insoluble in water and cannot be used to prepare metal plating sealants. Insufficient solvent usage will also affect the grafting rate and salt spray resistance time.

[0061] 2. Compared with the five experimental groups, the use of butyl acetate as a solvent in the grafting reaction process shows that the solvent is safe and non-toxic, overcoming the disadvantages of petroleum ether being flammable and explosive. It also improves the grafting rate of acrylic acid and greatly extends the salt spray resistance time.

[0062] 3. Compared with the five experimental groups, it can be seen that the acrylic monomer should not be added too quickly, otherwise it will clump together and form a white waxy hard solid, which will prevent the reaction from proceeding.

[0063] Example 2

[0064] This embodiment provides an application of low molecular weight polyethylene wax and acrylic acid to synthesize polyethylene acrylic acid. The polyethylene acrylic acid solution described in Example 1 (including but not limited to any one of test groups one to five) is used to prepare a zinc plating sealant. Using the zinc plating sealant prepared in this embodiment, the neutral salt spray resistance of the metal reaches about 1500 hours after use. Due to its high corrosion resistance, the subsequent passivation process can be omitted.

[0065] Example 3

[0066] This embodiment provides an application of low molecular weight polyethylene wax and acrylic acid to synthesize polyethylene acrylic acid. The polyethylene acrylic acid solution described in Example 1 (including but not limited to any one of test groups one to five) is used to prepare a coating. The coating prepared using this embodiment exhibits high corrosion resistance, with a neutral salt spray resistance test of approximately 1500 hours for metals after use.

[0067] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A process for the preparation of a low molecular weight polyethylene wax and acrylic acid to synthesize polyethylene acrylic acid, characterized by: It comprises the following steps: Step one: 50-60 parts of polyethylene wax is added into 40-50 parts of butyl acetate, after stirring and dissolving, 0.1-0.2 parts of initiator is added; the molecular weight of the polyethylene wax is 800-1000; Step two: 10 parts of acrylic monomer is slowly dropped in 14-16 minutes, the solution begins to turn white, after dropping, 0.1-0.2 parts of initiator is added; at this time, the white precipitate in the solution is polyethylene acrylic acid; Step three: the supernatant of the solution is filtered off, and the lower white precipitate is vacuum dried to obtain polyethylene acrylic acid powder.

2. The process for the preparation of a low molecular weight polyethylene wax and acrylic synthetic polyethylene acrylic acid according to claim 1, characterized in that: The initiator is any one of potassium persulfate or ammonium persulfate.

3. The process for the preparation of a low molecular weight polyethylene wax and acrylic synthetic polyethylene acrylic acid according to claim 2, characterized in that: It also comprises step four, 20-30g of polyethylene acrylic acid powder is taken, 200ml of water is added, heated to 80℃, and then 2-3g of cosolvent is added to obtain a polyethylene acrylic acid solution.

4. The process for the preparation of a low molecular weight polyethylene wax and acrylic synthetic polyethylene acrylic acid according to claim 3, characterized in that: The cosolvent is any one of sodium salicylate, p-aminobenzoic acid, nicotinamide, or acetamide.

5. The process for the preparation of a low molecular weight polyethylene wax and acrylic synthetic polyethylene acrylic acid according to claim 4, characterized in that: The grafting rate of the polyethylene acrylic acid powder is measured by extracting the polyethylene acrylic acid powder with acetone for 20-24h, 0.5g of the powder is dissolved in hot xylene, then neutralized with sodium hydroxide-ethanol solution, using phenolphthalein as an indicator, and titrating the excess alkali with hydrochloric acid to measure the grafting rate.

6. Use of a low molecular weight polyethylene wax and acrylic acid to synthesize polyethylene acrylic acid, characterized in that: The polyethylene acrylic acid solution prepared by the preparation process of claim 3-5 is used to prepare a galvanized sealing agent.

7. Use of a low molecular weight polyethylene wax and acrylic acid to synthesize polyethylene acrylic acid, characterized in that: The polyethylene acrylic acid solution prepared by the preparation process of claim 3-5 is used to prepare a coating.

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