Preparation method of environment-friendly plastic coating resin

Abstract

The invention relates to a preparation method of environment-friendly plastic coating resin, which comprises the following steps: deoxidizing: adding a solvent into a reaction kettle, and removing oxygen in the solvent and the reaction kettle by using high-purity nitrogen; mixing the monomers: putting the hard monomer, the soft monomer, the carboxylic acid unsaturated monomer and the functional monomer into a reaction kettle containing a solvent; preparing a finished product: adding an initiator at a certain temperature, and keeping the temperature for a certain time; and residual monomer removal: supplementing a part of the initiator at a certain temperature, preserving heat for a certain time, increasing the monomer conversion rate, then cooling to room temperature, filtering and discharging to obtain the environment-friendly plastic coating resin needing to be prepared. In the preparation process, compounding of at least two hard monomers, compounding of at least two soft monomers and at least one solvent are used, and through a solvent polymerization process, the obtained resin has excellent printing adaptability and removable effect when being applied to plastics.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of plastic coating resin, and particularly relates to a preparation method of an environmentally-friendly plastic coating resin which has simple preparation process, stable product, excellent adhesion on a substrate, excellent ink printability, excellent ink compatibility and excellent alkali removal performance. BACKGROUND

[0002] Currently, the outer packaging materials used in the packaging industry mainly include PP, PET, PE, PETG and synthetic paper, and plastics are mainly used; the inks used include UV ink, solvent ink, water ink and weak solvent ink; and the coating resins mainly include acrylate and polyurethane.

[0003] At present, a large amount of plastics are used in food packaging, disposable products, agricultural materials and industrial fillers, and the pollution caused by the plastics to the ecological environment and landscape is difficult to degrade and has a degradation period of hundreds of years.

[0004] Tobacco bamboo is used to replace plastics, and research and development of polylactic acid degradable materials are carried out. However, the cost of tobacco bamboo is high, and the maturity of PLA materials is still poor. Therefore, recycling and reuse of plastics are still the mainstream trend.

[0005] However, the packaging materials need to be printed with fine patterns or related information, and the transparency and processability of the products are seriously affected when the packaging materials are recycled, so that the recycling rate is low. SUMMARY

[0006] In view of the above problems, the main purpose of the present application is to provide a preparation method of an environmentally-friendly plastic coating resin which has simple preparation process, stable product, excellent adhesion on a substrate, excellent ink printability, excellent ink compatibility and excellent alkali removal performance.

[0007] The present application solves the above technical problems by the following technical scheme: a preparation method of an environmentally-friendly plastic coating resin, which comprises the following steps:

[0008] Step (1), oxygen removal: adding a solvent into a reaction kettle, and removing oxygen in the solvent and the reaction kettle by using high-purity nitrogen;

[0009] Step (2), monomer mixing: adding hard monomers, soft monomers, carboxylic acid unsaturated monomers and functional monomers into the reaction kettle containing the solvent;

[0010] Step (3), preparation of finished product: adding an initiator at a certain temperature, and keeping the temperature for a certain time;

[0011] Step (4), removing residual monomers: adding part of initiator at a certain temperature, and keeping for a certain time to improve monomer conversion rate, then cooling to room temperature, filtering the product, and obtaining the environment-friendly plastic coating resin to be prepared;

[0012] The raw materials for preparing the environment-friendly plastic coating resin include the following components in the following weight fractions: 10-70 parts by weight of hard monomer, 20-80 parts by weight of soft monomer, 0.1-10 parts by weight of carboxylic acid unsaturated monomer, 0.1-10 parts by weight of functional monomer, 0.1-5 parts by weight of initiator, and 200-350 parts by weight of solvent.

[0013] In the specific embodiment of the present application, the hard monomer is selected from one or a mixture of several of methyl methacrylate (MMA), styrene (SM), acrylonitrile (CAN) and vinyl acetate (PEVA).

[0014] In the specific embodiment of the present application, the soft monomer is selected from one or a mixture of several of ethyl acrylate (EA), butyl acrylate (BA), isooctyl acrylate (2-EHA) and hydroxyethyl acrylate (HEA).

[0015] In the specific embodiment of the present application, the carboxylic acid unsaturated monomer is selected from one or a mixture of several of acrylic acid (AA), methacrylic acid (MAA), itaconic acid (ITA) and maleic acid (MA).

[0016] In the specific embodiment of the present application, the functional monomer includes cross-linking monomer and / or molecular weight regulator, the cross-linking monomer is selected from one or a mixture of several of diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH), organic zinc salt, organic aluminum salt, diallyl phthalate (DAP) and ethylene glycol dimethacrylate (EGDMA), and the molecular weight regulator is selected from one or a mixture of several of mercaptoethanol (ME), mercaptopropionic acid (3-MPA), n-butyl mercaptopropionate, alpha-methyl styrene dimer (AMSD), n-dodecyl mercaptan and tert-dodecyl mercaptan.

[0017] In the specific embodiment of the present application, the initiator is selected from one or a mixture of several of azobisisobutyronitrile (AIBN), azobisisoheptyl nitrile (AIVN), dibenzoyl peroxide (BPO), dodecanoyl peroxide, dicyclohexyl peroxydicarbonate, cumene hydroperoxide, hydrogen peroxide and the like.

[0018] In the specific embodiment of the present application, in step (1), the solvent is one or a mixture of several of ethyl acetate, toluene, butyl acetate, acetone, ethanol, isopropyl alcohol, butanone, methyl isobutyl ketone and the like.

[0019] In the specific embodiment of the present application, in step (3), the temperature is set to 50-90°C, and the holding time is 8-24H.

[0020] In the specific embodiment of the present application, in step (4), the temperature is set to 60-100°C, and the holding time is 2-10H.

[0021] In the specific embodiment of the present application, the molecular weight of the plastic coating resin is 5000-200000, and the solid content is 20-40%.

[0022] The positive progress effect of the present application is that the preparation method of the environmentally friendly plastic coating resin has the following advantages: the preparation method of the environmentally friendly plastic coating resin provided by the present application uses the compounding of at least two hard monomers, the compounding of at least two soft monomers, and the compounding of at least two solvents during the preparation process. Especially, the solvent polymerization and multiple feeding process is adopted, compared with the traditional one-time feeding, the resin prepared by the polymerization process can achieve the effect of rapid alkali washing under the condition of low acid value, the preparation process is simple, the product is stable, and the acrylic glue obtained has excellent adhesion, excellent ink printing property, excellent ink compatibility, and excellent alkali washing removal performance. DETAILED DESCRIPTION

[0023] The preferred embodiment of the present application is given below to explain the technical scheme of the present application in detail.

[0024] The present application provides a preparation method of an environmentally friendly plastic coating resin, which comprises the following steps:

[0025] Step (1), oxygen removal: adding a solvent into a reaction kettle, and removing oxygen in the solvent and the reaction kettle by using high-purity nitrogen;

[0026] Step (2), monomer mixing: adding hard monomers, soft monomers, carboxylic acid unsaturated monomers, and functional monomers into the reaction kettle containing the solvent;

[0027] Step (3), preparation of finished product: adding an initiator at a certain temperature, and holding for a certain time;

[0028] Step (4), removal of residual monomers: adding part of the initiator at a certain temperature, holding for a certain time to improve the monomer conversion rate, then cooling to room temperature, filtering the material, and obtaining the environmentally friendly plastic coating resin to be prepared;

[0029] The raw material for preparing the environment-friendly plastic coating resin comprises the following components in the following weight fractions: 10-70 parts by weight of hard monomer, 20-80 parts by weight of soft monomer, 0.1-10 parts by weight of carboxylic unsaturated monomer, 0.1-10 parts by weight of functional monomer, 0.1-5 parts by weight of initiator, and 200-350 parts by weight of solvent.

[0030] The hard monomer in the application is selected from one or a mixture of several of methyl methacrylate (MMA), styrene (SM), acrylonitrile (CAN) and vinyl acetate (PEVA).

[0031] The soft monomer in the application is selected from one or a mixture of several of ethyl acrylate (EA), butyl acrylate (BA), isooctyl acrylate (2-EHA) and hydroxyethyl acrylate (HEA).

[0032] The carboxylic unsaturated monomer in the application is selected from one or a mixture of several of acrylic acid (AA), methacrylic acid (MAA), itaconic acid (ITA) and maleic acid (MA).

[0033] The functional monomer in the application comprises cross-linking monomer selected from one or a mixture of several of diacetone acrylamide (DAAM), adipic acid dihydrazide (ADH), organic zinc salt, organic aluminum salt, diallyl phthalate (DAP) and ethylene glycol dimethacrylate (EGDMA), and / or molecular weight regulator selected from one or a mixture of several of mercaptoethanol (ME), mercaptopropionic acid (3-MPA), n-butyl mercaptopropionate, alpha-methyl styrene dimer (AMSD), n-dodecyl mercaptan and tert-dodecyl mercaptan.

[0034] The initiator in the application is selected from one or a mixture of several of azobisisobutyronitrile (AIBN), azobisisoheptyl nitrile (AIVN), dibenzoyl peroxide (BPO), dodecanoyl peroxide, dicyclohexyl peroxydicarbonate, cumene hydroperoxide, hydrogen peroxide and the like.

[0035] In step (1), the solvent is one or a mixture of several of ethyl acetate, toluene, butyl acetate, acetone, ethanol, isopropyl alcohol, butanone, methyl isobutyl ketone and the like. In step (3), the set temperature is 50-90℃, and the holding time is 8-24H. In step (4), the set temperature is 60-100℃, and the holding time is 2-10H.

[0036] The molecular weight of the environment-friendly plastic coating resin in the application is 5000-200000, and the solid content is 20-40%.

[0037] The application is further explained below in connection with embodiments which aim at better illustrating the inventive concept and embodying the essential characteristics of the application, and therefore should not be considered as limiting the scope of the protection. It is also specifically pointed out that the particular experimental methods and equipment described in the examples are not to be considered in a limiting sense, unless otherwise specifically stated in the examples, and that the reagents used are commercially available unless otherwise indicated.

[0038] Example 1

[0039] The embodiment provides a preparation method of an environment-friendly plastic coating resin, and the preparation method comprises the following steps:

[0040] 1. Oxygen removal: 180 parts of ethyl acetate and 50 parts of acetone are added into a 1L reaction kettle, high-purity nitrogen is introduced into the reaction kettle to replace the oxygen in the reaction kettle, and then heating is performed to increase the temperature to 55 DEG C.

[0041] 2. Monomer mixing: 50 parts of methyl methacrylate, 25 parts of styrene, 15 parts of butyl acrylate and 5 parts of isooctyl acrylate are mixed, and then the mixture is quickly added into the reaction kettle at one time.

[0042] 3. Product preparation: 20 parts of ethyl acetate is used to dissolve 2 parts of azobisisobutyronitrile, and then the solution is added into the reaction kettle at one time when the temperature of the reaction kettle reaches 55 DEG C. Then, 12 hours of heat preservation is performed.

[0043] 4. Monomer supplementing: 5 parts of methyl methacrylate is added into the reaction kettle, and then 12 hours of heat preservation is performed.

[0044] 5. Residual monomer removal: 10 parts of ethyl acetate is used to dissolve 0.5 parts of azobisisobutyronitrile, the temperature of the reaction kettle is increased to 70 DEG C, and then the solution is added into the reaction kettle at one time, and then 6 hours of heat preservation is performed. The temperature is decreased to discharge the product, and the alkali-washable plastic coating resin is obtained.

[0045] The "parts" above are all weight parts.

[0046] Example 2

[0047] The embodiment provides a preparation method of an environment-friendly plastic coating resin, and the preparation method comprises the following steps:

[0048] 1. Oxygen removal: 180 parts of ethyl acetate and 50 parts of acetone are added into a 1L reaction kettle, high-purity nitrogen is introduced into the reaction kettle to replace the oxygen in the reaction kettle, and then heating is performed to increase the temperature to 55 DEG C.

[0049] 2. Monomer mixing: 50 parts of ethyl acetate and 50 parts of acetone are added into a 1L reaction kettle, high-purity nitrogen is introduced into the reaction kettle to replace the oxygen in the reaction kettle, and then heating is performed to increase the temperature to 55 DEG C.

[0050] 3. Product preparation: 20 parts of ethyl acetate were used to dissolve 2 parts of azobisisobutyronitrile. When the temperature of the reaction kettle reached 55 degrees, it was added to the reaction kettle at once. Then it was kept warm for 12 hours.

[0051] 4. Additional monomer: 5 parts of methacrylic acid were added dropwise to the reaction kettle. Then it was kept warm for 12 hours.

[0052] 5. Residual monomer removal: 10 parts of ethyl acetate were used to dissolve 0.5 parts of azobisisobutyronitrile, and the temperature of the reaction kettle was raised to 70 degrees. Then it was added to the reaction kettle at once, and kept warm for 6 hours. After cooling, the product was discharged, and a plastic coating resin that could be washed with alkali was obtained.

[0053] The "parts" above are all weight parts.

[0054] Example 3:

[0055] The embodiment provides a preparation method of an environmentally friendly plastic coating resin, and the preparation method comprises the following steps:

[0056] 1. Oxygen removal: 180 parts of ethyl acetate and 50 parts of acetone were added to a 1L reaction kettle, then high-purity nitrogen was introduced into the reaction kettle to replace the oxygen in the reaction kettle. Then it was heated to 55 degrees.

[0057] 2. Monomer mixing: 50 parts of methyl methacrylate, 15 parts of styrene, 15 parts of butyl acrylate, 5 parts of isooctyl acrylate and 5 parts of methacrylic acid were mixed, and then added to the reaction kettle at once.

[0058] 3. Product preparation: 20 parts of ethyl acetate were used to dissolve 2 parts of azobisisobutyronitrile. When the temperature of the reaction kettle reached 55 degrees, it was added to the reaction kettle at once. Then it was kept warm for 12 hours.

[0059] 4. Additional monomer: 10 parts of methacrylic acid were added dropwise to the reaction kettle, and then it was kept warm for 12 hours.

[0060] 5. Residual monomer removal: 10 parts of ethyl acetate were used to dissolve 0.5 parts of azobisisobutyronitrile, and the temperature of the reaction kettle was raised to 70 degrees. Then it was added to the reaction kettle at once, and kept warm for 6 hours. After cooling, the product was discharged, and a plastic coating resin that could be washed with alkali was obtained.

[0061] The "parts" above are all weight parts.

[0062] Example 4:

[0063] The embodiment provides a preparation method of an environmentally friendly plastic coating resin, and the preparation method comprises the following steps:

[0064] 1. Deoxygenation: Add 180 parts of ethyl acetate and 50 parts of acetone to a 1L reactor, then purge the reactor with high-purity nitrogen to replace the oxygen inside. Then heat to 55 degrees Celsius.

[0065] 2. Monomer mixing: Mix 50 parts of methyl methacrylate, 20 parts of styrene, 15 parts of butyl acrylate and 5 parts of isooctyl acrylate, and then quickly add them into the reactor all at once.

[0066] 3. Product Preparation: Dissolve 2 parts of dicyclohexyl peroxide dicarbonate in 20 parts of ethyl acetate. Add the solution all at once to the reactor once the reactor temperature reaches 55 degrees Celsius. Then maintain the temperature for 12 hours.

[0067] 4. Add monomer: Add 10 parts of methacrylic acid dropwise to the reactor. Continue to react at this temperature for 12 hours.

[0068] 5. Residual resin removal: Dissolve 0.5 parts of dicyclohexyl peroxide in 10 parts of ethyl acetate, and heat the reactor to 70 degrees Celsius. Then add the solution to the reactor all at once and keep it at that temperature for 6 hours. Cool down and discharge the material to obtain the alkali-washable plastic coating resin.

[0069] All "portions" mentioned above refer to portions by weight.

[0070] Comparative Example 1 (based on Example 1, using a solvent and a soft monomer):

[0071] This embodiment provides a method for preparing an environmentally friendly plastic coating resin, which includes the following steps:

[0072] 1. Deoxygenation: Add 230 parts of ethyl acetate to a 1L reactor, then purge the reactor with high-purity nitrogen to replace the oxygen inside. Then heat to 55 degrees Celsius.

[0073] 2. Monomer mixing: Mix 50 parts of methyl methacrylate, 25 parts of styrene, and 20 parts of butyl acrylate, and then quickly add the mixture into the reactor all at once.

[0074] 3. Product preparation: Dissolve 2 parts of azobisisobutyronitrile in 20 parts of ethyl acetate. Add the solution to the reactor all at once once the reactor temperature reaches 55 degrees Celsius. Then maintain the temperature for 12 hours.

[0075] 4. Add monomer: Add 5 parts of methacrylic acid dropwise to the reaction vessel and keep it at the temperature for 12 hours.

[0076] 5. Residual Residue Removal: Dissolve 0.5 parts of azobisisobutyronitrile in 10 parts of ethyl acetate, and heat the reactor to 70 degrees Celsius. Then add the solution to the reactor all at once and maintain the temperature for 6 hours. Cool down and discharge the material to obtain the alkali-washable plastic coating resin.

[0077] All "portions" mentioned above refer to portions by weight.

[0078] Comparative Example 2 (based on Comparative Example 1, with the addition of a molecular weight regulator):

[0079] This embodiment provides a method for preparing an environmentally friendly plastic coating resin, which includes the following steps:

[0080] 1. Deoxygenation: Add 230 parts of ethyl acetate to a 1L reactor, then purge the reactor with high-purity nitrogen to replace the oxygen inside. Then heat to 55 degrees Celsius.

[0081] 2. Monomer mixing: Mix 50 parts of methyl methacrylate, 25 parts of styrene, 20 parts of butyl acrylate and 0.3 parts of dodecyl mercaptan, and then quickly add the mixture into the reactor all at once.

[0082] 3. Product preparation: Dissolve 2 parts of azobisisobutyronitrile in 20 parts of ethyl acetate. Add the solution to the reactor all at once once the reactor temperature reaches 55 degrees Celsius. Then maintain the temperature for 12 hours.

[0083] 4. Add monomer: Add 5 parts of methacrylic acid dropwise to the reactor. Keep the reaction at this temperature for 12 hours.

[0084] 5. Residual Residue Removal: Dissolve 0.5 parts of azobisisobutyronitrile in 10 parts of ethyl acetate, and heat the reactor to 70 degrees Celsius. Then add the solution to the reactor all at once and maintain the temperature for 6 hours. Cool down and discharge the material to obtain the alkali-washable plastic coating resin.

[0085] All "portions" mentioned above refer to portions by weight.

[0086] Efficacy test:

[0087] 1. Printing performance test: Tested according to GB / T 17497.1-2012 standard.

[0088] 2. Coating cleaning conditions: Place the film in a 50*150mm size into an 80-degree 3% sodium hydroxide solution, mechanically stir for 20 minutes, and observe the coating peeling.

[0089] 3. Ink peeling test: The test shall be conducted in accordance with GB / T 15962-2008.

[0090] The performance test results of an alkaline washable thin film coating adhesive obtained in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0091] Table 1

[0092]

[0093] Note: A higher printability score indicates better printability; a higher coating peeling score indicates cleaner cleaning.

[0094] As can be seen from Table 1:

[0095] (1) Comparison of Example 1 and Example 2: Example 1 used two solvent combinations, two hard monomers, and two soft monomers. Compared with Example 1, Example 2 used one of two different solvents. The acrylate adhesive obtained in Example 2 had a larger molecular weight, although the printing performance was comparable, the alkaline cleaning performance was worse. This indicates that the solvent toluene is beneficial for increasing the molecular weight of the adhesive, but a higher molecular weight is not conducive to alkaline cleaning.

[0096] (2) Comparison between Example 1 and Example 3: Example 1 used two dissolution combinations, two hard monomers, and two soft monomers. Compared with Example 1, Example 3 used a higher methacrylic acid content. The acrylate glue obtained in Example 3 had a slightly higher molecular weight, but its printing performance was slightly worse, while its alkaline washing effect was excellent.

[0097] (3) Comparison between Example 1 and Example 4: Example 1 used two dissolution combinations, two hard monomers, and two soft monomers. Compared with Example 1, Example 4 used a relatively more efficient initiator. The acrylate adhesive obtained in Example 4 has a smaller molecular weight and excellent printing performance and alkaline washing effect.

[0098] (4) Comparative Example 1 uses a monomer solvent and a single soft monomer, which is beneficial to increase the molecular weight, but the printing performance and alkaline washing effect are poor. Comparative Example 2 adds a molecular weight regulator, which reduces the molecular weight, but the improvement in printing performance and alkaline washing effect is not obvious.

[0099] This invention provides a method for preparing an environmentally friendly plastic coating resin. The preparation process involves a blend of at least two hard monomers, a blend of at least two soft monomers, and a blend of at least two solvents. In particular, the solvent polymerization and multi-stage feeding process, compared to traditional single-stage feeding, allows the resin prepared by this polymerization process to achieve rapid alkali washing even under low acid value conditions. The preparation process is simple, the product is stable, and the obtained plastic coating resin exhibits excellent adhesion to substrates, excellent ink printability, excellent ink compatibility, and excellent alkali removal performance.

[0100] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A method for preparing an environmentally friendly plastic coating resin, characterized in that, The preparation method of the environmentally friendly plastic coating resin includes the following steps: Step (1), Deoxygenation: Add the solvent to the reaction vessel and use high-purity nitrogen to remove the solvent and oxygen in the reaction vessel; Step (2), Monomer mixing: Hard monomers, soft monomers, carboxylic acid unsaturated monomers and functional monomers are placed in a reaction vessel containing solvent; Step (3), Preparation of the finished product: Add the initiator at a certain temperature and keep it warm for a certain time; Step (4), Removing residual monomers: Add a portion of the initiator at a certain temperature and keep it warm for a certain time to improve the monomer conversion rate. Then cool it down to room temperature, filter and discharge the material to obtain the environmentally friendly plastic coating resin to be prepared. The raw materials used to prepare the environmentally friendly plastic coating resin include the following components in parts by weight: 10-70 parts by weight of hard monomer, 20-80 parts by weight of soft monomer, 0.1-10 parts by weight of carboxylic acid unsaturated monomer, 0.1-10 parts by weight of functional monomer, 0.1-5 parts by weight of initiator, and 200-350 parts by weight of solvent.

2. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The hard monomer is selected from one or a mixture of several of methyl methacrylate (MMA), styrene (SM), acrylonitrile (CAN), and vinyl acetate (PEVA).

3. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The soft monomer is selected from one or a mixture of several of ethyl acrylate (EA), butyl acrylate (BA), isooctyl acrylate (2-EHA), and hydroxyethyl acrylate (HEA).

4. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The carboxylic acid unsaturated monomer is selected from one or a mixture of several of acrylic acid (AA), methacrylic acid (MAA), itaconic acid (ITA), and maleic acid (MA).

5. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The functional monomers include cross-linking monomers and / or molecular weight regulators. The cross-linking monomers are selected from one or a mixture of several of diacetone acrylamide (DAAM), adipate dihydrazide (ADH), organozinc salts, organoaluminum salts, diallyl phthalate (DAP), and ethylene glycol dimethacrylate (EGDMA). The molecular weight regulators are selected from one or a mixture of several of mercaptoethanol (ME), mercaptopropionic acid (3-MPA), n-butyl mercaptopropionate, α-methylstyrene dimer (AMSD), n-dodecyl mercaptan, and tert-dodecyl mercaptan.

6. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The initiator is selected from one or a mixture of several of the following: azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (AIVN), benzoyl peroxide (BPO), dodecyl peroxide, dicyclohexyl percarbonate, cumene hydroperoxide, and hydrogen peroxide.

7. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: In step (1), the solvent is one or a mixture of several of the following: ethyl acetate, toluene, butyl acetate, acetone, ethanol, isopropanol, butanone, methyl isobutyl ketone, etc.

8. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: In step (3), the temperature is set to 50-90℃ and the heat preservation time is 8-24H.

9. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: In step (4), the temperature is set to 60-100℃ and the holding time is 2-10H.

10. The method for preparing the environmentally friendly plastic coating resin according to claim 1, characterized in that: The molecular weight of the plastic coating resin is 5,000 to 200,000, and the solid content is 20-40%.

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