CN113088152B

CN113088152B - Multifunctional water-based paint for inner wall plate of refrigerated container

Info

Publication number: CN113088152B
Application number: CN202110373800.8A
Authority: CN
Inventors: 郑玉婴; 杨文杰
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2021-04-07
Filing date: 2021-04-07
Publication date: 2022-04-12
Anticipated expiration: 2041-04-07
Also published as: CN113088152A

Abstract

The invention discloses a multifunctional water-based paint for inner wall plates of refrigerated containers, which is prepared by synthesizing graphene oxide (GC @ GO) with chitosan quaternary ammonium salt grafted on the surface, reducing the graphene oxide, and treating the reduced graphene oxide with acetic acid to obtain cation reduced graphene oxide (GC @ RGO)⁺) And finally, adding the modified acrylic acid into KH566 modified water-based acrylic paint as an antibacterial reinforcing agent, and adding a leveling agent and a defoaming agent to prepare the multifunctional water-based paint. The coating has the advantages of high hardness, high adhesive force, chemical reagent resistance and antibacterial performance, is very environment-friendly, and has great social and economic benefits in cold-chain containers.

Description

Multifunctional water-based paint for inner wall plate of refrigerated container

Technical Field

The invention belongs to the technical field of water-based paint, and particularly relates to multifunctional water-based paint for inner wall plates of refrigerated containers.

Background

With the increasing progress of global science and technology and the continuous improvement of the living standard of people, the food preservation problem is more and more concerned by people, and the development of a cold chain drives the production and development of refrigeration equipment. In the current cold chain storage and transportation process, not only the low-temperature environment required by food needs to be ensured, but also the uniformity in a flow field needs to be considered. Compared with a common truck, the refrigerated container transportation can ensure that food has better fresh-keeping capacity in a low-temperature environment. The refrigerated container can be butted in land, sea and air transportation, has high flexibility, becomes an important link in cold chain transportation, and also becomes one of the most important goods transportation modes in international trade.

The container is mainly prepared from steel plates, light alloy, fiber reinforced plastics, plywood and the like. In order to reduce the influence of corrosive substances such as water inside the container, a protective coating is usually applied to the interior of the container, and the coating needs to have high hardness and adhesion because cargo impacts and rubs against the inner plates during transportation. Meanwhile, new coronavirus is outbreaking worldwide, and the existence of new coronavirus has been detected many times by cold chain transportation as a possible transmission way, so that the development of a coating with antibacterial function is necessary and meets the current social requirements.

Organic coatings (e.g., acrylics, epoxies, etc.) are now widely used to prevent corrosion of metal surfaces. The water-based acrylic emulsion has extremely low Volatile Organic Compound (VOC) content, is easy to prepare, has good wear resistance and strong adhesive force to different base materials, and can be used as a proper organic coating and a physical barrier. Different nano materials are used as reinforcing agents to be blended with the waterborne acrylic amino baking varnish, so that the long-acting anticorrosion effect can be effectively generated, and the modified waterborne coating has unique nano material performance.

Disclosure of Invention

The invention aims to provide the multifunctional water-based emulsion with high hardness, high adhesive force, chemical reagent resistance and antibacterial property, which has great potential when being used for inner wall plates of refrigerated containers.

In order to achieve the purpose, the invention adopts the following technical scheme:

a multifunctional water-based paint for inner wall plates of refrigerated containers comprises the following components in percentage by weight:

94 to 99 percent of KH566 modified acrylic emulsion,

1 to 5 percent of antibacterial reinforcing agent,

0.1 to 0.5 percent of flatting agent,

0.1 to 0.5 percent of defoaming agent,

the sum of the weight percentages of the components is 100 percent.

Wherein the antibacterial reinforcing agent is cationic reduced graphene oxide (GC @ RGO) with chitosan quaternary ammonium salt grafted on the surface⁺). The preparation method comprises the following steps:

1) preparation of CH @ GO: weighing 0.2g of GO, pouring into a beaker filled with 100mL of deionized water, placing into an ultrasonic cleaner for dispersing for 1h, then adding 1mL of acetic acid, uniformly mixing, slowly adding 1g of Chitosan (CH) under a magnetic stirring state, reacting for 5h at 25 ℃, filtering and washing the obtained product until the pH =7, taking out a filter cake, freeze-drying to obtain graphene oxide grafted chitosan (CH @ GO), and storing in a glass dryer for later use;

2) preparation of GC @ GO: uniformly dispersing 0.1g of CH @ GO prepared in the step 1) into 30ml of deionized water, adjusting the pH value to 9 by using 0.16mol/L NaOH solution, adding 20ml of epoxypropyltrimethylammonium chloride solution with the concentration of 100mg/ml, heating in a water bath to 60 ℃, reacting for 2h, standing for 24h, repeatedly cleaning a sample, and drying in a 60 ℃ drying oven to obtain graphene oxide (GC @ GO) with chitosan quaternary ammonium salt grafted on the surface;

3）GC@RGO⁺the preparation of (1): dispersing 0.1g of GC @ GO prepared in the step 2) in 100mL of DMF, carrying out ultrasonic treatment for 1h, then placing the mixture in an oil bath at 80 ℃ for heat preservation reaction for 24h, then cooling to 25 ℃, washing with ethanol and deionized water to remove residual solvent, carrying out centrifugal separation to obtain a product, and freeze-drying to obtain reduced graphene oxide (GC @ RGO) powder with the surface grafted with chitosan quaternary ammonium salt; adding the obtained GC @ RGO into acetone, ultrasonically dispersing for 30min, slowly adding 1.35g of acetic acid into the acetone while stirring at 28 ℃, and stirring for 3 h to obtain GC @ RGO⁺And dried at room temperature for 2 days.

The KH566 modified acrylic emulsion is prepared by adopting a semi-continuous dropwise adding seed emulsion polymerization method, and the preparation steps are as follows:

step 1, adding 80g of deionized water, 0.24g of sodium dodecyl diphenyl ether disulfonate (CR-MADS) and 0.24g of Alkylphenol Polyoxyethylene (APEO) into a four-neck flask provided with a condenser pipe, a stirrer and a nitrogen protection device in sequence to prepare a compound emulsifier and 0.4g of NaHCO₃A buffering agent, namely stirring and mixing at 250 r/min, simultaneously and slowly dripping 24g of Methyl Methacrylate (MMA) and 8g of Butyl Acrylate (BA) into a four-neck flask, and preserving the temperature at 30 ℃ for 1h to obtain seed emulsion serving as a core layer; the flask containing 20g of deionized water was charged with a main charge8g of MMA and 16g of BA as well as 4g of functional monomer Acrylic Acid (AA), 4g of hydroxypropyl methacrylate (HPMA), 0.36g of CR-MADS and 0.36g of APEO as emulsifiers are stirred for 1 hour at the temperature of 30 ℃ to prepare a pre-emulsion as a shell layer;

step 2, weighing 0.4g of potassium persulfate (KPS) to be dissolved in 20g of deionized water to obtain an initiator solution, heating the initiator solution to 65 ℃, adding 1/3 of the initiator solution into the seed emulsion serving as the core layer, reacting for 0.5h to obtain a blue-emitting seed emulsion, carrying out heat preservation reaction for 0.5h, beginning to dropwise add the pre-emulsion serving as the shell layer and the rest of the initiator, controlling the dropwise adding time within 1-2 h, heating to 75 ℃ after the dropwise adding is finished, reacting for 4h, cooling to room temperature after the reaction is completed, adjusting the pH value to 7-7.5, and discharging to obtain an acrylic emulsion;

step 3, pouring the KH566 coupling agent into 90vol% ethanol solution according to the mass ratio of 1:4, adjusting the pH to 3-4 with phosphoric acid, stirring and hydrolyzing at room temperature for 1h, then pouring into the prepared acrylic emulsion, and stirring at high speed for 1h to obtain KH566 modified acrylic emulsion; the dosage of the KH566 coupling agent is 5-10wt% of the dosage of the acrylic emulsion.

The defoaming agent is specifically a BYK organic silicon defoaming agent.

The leveling agent is specifically a BYK leveling agent.

The preparation method of the multifunctional water-based paint is characterized in that the prepared increaser, flatting agent and defoaming agent are introduced into KH566 modified acrylic emulsion, and then the mixture is stirred for 30min at the rotating speed of 800-1000 r/min.

The invention has the following remarkable advantages:

(1) chitosan is a natural polymer with antibacterial activity, and has the advantages of high penetrability, good environmental stability, functional activity, biocompatibility, safety and the like of natural polymers, but the antibacterial activity of chitosan is not high. According to the invention, the quaternary ammonium salt of chitosan with excellent antibacterial effect can be obtained by performing quaternization modification on the quaternary ammonium salt, and bacteria can be killed by directly contacting the quaternary ammonium salt with the bacteria without releasing active substances, so that the antibacterial property of the coating is long-acting, the residual toxicity is greatly reduced, and the safety is improved. RGO⁺As coating barrier, RGO on the one hand⁺Leads to the increase of the tortuosity of a diffusion path, obviously reduces the length of the permeation path, improves the solvent resistance and the corrosion resistance of a paint film, and on the other hand, RGO⁺The positive charge on the surface can form hydrogen bond and electrostatic attraction with bacteria, so that cells can not take up important nutrients and die immediately. Therefore, the cationic reduced graphene oxide with the surface grafted with the chitosan quaternary ammonium salt used in the invention can play double roles of antibiosis and enhancement.

(2) The invention adopts the water-based acrylic emulsion as the raw material, and the preparation process does not need to add an organic solvent to assist in dissolving the acrylic resin, so that the VOC emission is extremely low, and the preparation method is very green and environment-friendly. According to the invention, KH566 coupling agent is selected to modify the acrylic emulsion, and silicon hydroxyl and epoxy in KH566 can react with hydroxyl and carboxyl in the acrylic emulsion to increase the crosslinking density (as shown in figures 2 and 3), so that the mechanical property of the paint film is enhanced, and the adhesion with the inner plate of the container can be improved.

(3) According to the method, firstly, chitosan (CH @ GO) is introduced through an amide reaction between carboxyl on the surface of graphene oxide and amino of chitosan, then H on the amino of the chitosan is replaced through a small-molecule quaternary ammonium salt epoxypropyl trimethyl ammonium chloride ring-opening reaction to prepare graphene oxide (GC @ GO) with the surface grafted with chitosan quaternary ammonium salt, finally, graphene oxide is reduced through hydrothermal method, and GC @ RGO is obtained through acetic acid treatment⁺And then the modified acrylic emulsion is added into KH566 modified acrylic emulsion in a physical blending mode to obtain the multifunctional water-based emulsion with high hardness, high adhesive force, chemical reagent resistance and antibacterial property, and the emulsion has great potential when being applied to inner plates of containers.

Drawings

Fig. 1 is a Zeta potential diagram of different graphene materials.

FIG. 2 is a graph showing a comparison of the surface morphology of paint films obtained from the aqueous acrylic paint (a) of comparative example 1 and the aqueous acrylic paint (b) modified with 2 KH 566.

FIG. 3 is a comparison of the crosslinking ratio of the resulting paint films of the comparative column 1 aqueous acrylic paint and the comparative column 2 KH566 modified aqueous acrylic paint.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

1) Preparation of CH @ GO:

weighing 0.2g of GO, pouring into a beaker filled with 100mL of deionized water, placing into an ultrasonic cleaning machine for dispersing for 1h, then adding 1mL of acetic acid, uniformly mixing, slowly adding 1g of CH under a magnetic stirring state, reacting for 5h at 25 ℃, filtering and washing the obtained product until the pH =7, taking out a filter cake, freeze-drying to obtain CH @ GO, and storing in a glass dryer for later use;

2) preparation of GC @ GO:

uniformly dispersing 0.1g of prepared CH @ GO into 30ml of deionized water, adjusting the pH value to 9 by using 0.16mol/L NaOH solution, adding 20ml of epoxypropyltrimethylammonium chloride solution with the concentration of 100mg/ml, heating in a water bath to 60 ℃, reacting for 2 hours, standing for 24 hours, repeatedly cleaning a sample, and drying in a 60 ℃ drying oven to obtain GC @ GO;

3）GC@RGO⁺the preparation of (1):

dispersing 0.1g of prepared GC @ GO in 100mL of DMF, carrying out ultrasonic treatment for 1h, then placing the mixture in an oil bath at the temperature of 80 ℃ for heat preservation reaction for 24h, then removing a heat source, cooling the mixture to 25 ℃, washing the mixture with ethanol and deionized water to remove residual solvent, carrying out centrifugal separation to obtain a product, and freeze-drying the product to obtain GC @ RGO powder; adding the obtained GC @ RGO into acetone, ultrasonically dispersing for 30min, slowly adding 1.35g of acetic acid into the acetone while stirring at 28 ℃, and stirring for 3 h to obtain GC @ RGO⁺Drying at room temperature for 2 days;

4) preparation of KH566 modified acrylic emulsion:

80g of deionized water, 0.24g of CR-MADS and 0.24g of APEO (ammonium paratolute) prepared compound emulsifier and 0.4g of NaHCO are sequentially added into a four-neck flask provided with a condenser pipe, a stirrer and a nitrogen protection device₃A buffer, mixing the mixture with stirring at 250 r/min and simultaneously slowly dripping the seed monomer into the four-neck flask24g of MMA and 8g of BA, and keeping the temperature at 30 ℃ for 1h to obtain seed emulsion serving as a nuclear layer;

adding 8g of main monomer MMA, 16g of BA, 4g of functional monomer AA, 4g of HPMA, 0.36g of CR-MADS and 0.36g of APEO into a conical flask filled with 20g of deionized water, and stirring for 1 hour at the temperature of 30 ℃ to prepare pre-emulsion serving as a shell layer;

weighing 0.4g of KPS, dissolving in 20g of deionized water to obtain an initiator solution, heating to 65 ℃, adding 1/3 of the initiator solution into the seed emulsion serving as a nuclear layer, reacting for 0.5h to obtain a blue-emitting seed emulsion, keeping the temperature, reacting for 0.5h, beginning to dropwise add the pre-emulsion serving as a shell layer and the rest of the initiator, dropwise adding for about 1-2 h, heating to 75 ℃ after dropwise adding, reacting for 4h, cooling to room temperature after complete reaction, adjusting the pH value to 7-7.5, and discharging to obtain an acrylic emulsion;

adding KH566 coupling agent which is 5wt% of the amount of the acrylic emulsion into 90vol% ethanol solution according to the mass ratio of 1:4, adjusting the pH to 3-4 with phosphoric acid, stirring and hydrolyzing at room temperature for 1h, then adding the obtained mixture into the prepared acrylic emulsion, and stirring at high speed for 1h to obtain the KH566 modified acrylic emulsion.

5) Preparing the multifunctional water-based paint:

introduction of prepared GC @ RGO into KH566 modified acrylic emulsion⁺Stirring the powder, a BYK organic silicon defoaming agent and a BYK flatting agent at the rotating speed of 900 r/min for 30min to obtain GC @ RGO⁺KH566 modified water-based acrylic paint, wherein the weight percentage of each raw material is as follows:

98.8 percent of KH566 modified acrylic emulsion,

GC@RGO⁺ 1%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Example 2

1) Preparation of CH @ GO: in the same manner as in the example 1,

2) preparation of GC @ GO: in the same manner as in the example 1,

3）GC@RGO⁺the preparation of (1): in the same manner as in the example 1,

4) preparation of KH566 modified acrylic emulsion: in the same manner as in the example 1,

5) preparing the multifunctional water-based paint:

97.8 percent of KH566 modified acrylic emulsion,

GC@RGO⁺ 2%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Example 3

1) Preparation of CH @ GO: in the same manner as in the example 1,

2) preparation of GC @ GO: in the same manner as in the example 1,

3）GC@RGO⁺the preparation of (1): in the same manner as in the example 1,

5) preparing the multifunctional water-based paint:

96.8 percent of KH566 modified acrylic emulsion,

GC@RGO⁺ 3%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Example 4

1) Preparation of CH @ GO: in the same manner as in the example 1,

2) preparation of GC @ GO: in the same manner as in the example 1,

3）GC@RGO⁺the preparation of (1): in the same manner as in the example 1,

5) preparing the multifunctional water-based paint:

95.8 percent of KH566 modified acrylic emulsion,

GC@RGO⁺ 4%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Example 5

1) Preparation of CH @ GO: in the same manner as in the example 1,

2) preparation of GC @ GO: in the same manner as in the example 1,

3）GC@RGO⁺the preparation of (1): in the same manner as in the example 1,

5) preparing the multifunctional water-based paint:

94.8 percent of KH566 modified acrylic emulsion,

GC@RGO⁺ 5%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 1

Preparation of the water-based acrylic paint:

80g of deionized water, 0.24g of CR-MADS and 0.24g of APEO (ammonium paratolute) prepared compound emulsifier and 0.4g of NaHCO are sequentially added into a four-neck flask provided with a condenser pipe, a stirrer and a nitrogen protection device₃A buffering agent, namely stirring and mixing at 250 r/min, simultaneously slowly dropwise adding 24g of MMA and 8g of BA in the four-neck flask, and keeping the temperature at 30 ℃ for 1h to obtain seed emulsion serving as a nuclear layer;

introducing a BYK organic silicon defoaming agent and a BYK flatting agent into the water-based acrylic emulsion, and stirring at the rotating speed of 900 r/min for 30min to obtain the water-based acrylic coating, wherein the weight percentage of each raw material is as follows:

99.8 percent of water-based acrylic emulsion,

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 2

Preparation of KH566 modified waterborne acrylic coating:

pouring KH566 coupling agent which is 5wt% of the amount of the acrylic emulsion into 90vol% ethanol solution according to the mass ratio of 1:4, adjusting the pH to 3-4 with phosphoric acid, stirring and hydrolyzing at room temperature for 1h, then pouring into the prepared acrylic emulsion, and stirring at high speed for 1h to obtain KH566 modified acrylic emulsion;

introducing a BYK organic silicon defoaming agent and a BYK flatting agent into KH566 modified acrylic emulsion, and stirring at the rotating speed of 900 r/min for 30min to obtain the water-based acrylic coating, wherein the weight percentage of each raw material is as follows:

KH566 modified acrylic emulsion 99.8%,

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 3

1) Preparation of GO: GO is prepared by the Hummers Method disclosed in the literature (by "student of Reduced Graphene Oxide Preparation by Hummers' Method and Related Characterization") by Ning Cao and Yuan Zhang;

2) preparation of KH566 modified acrylic emulsion: in the same manner as in the example 1,

3) preparation of water emulsion type acrylic acid composite coating:

introducing prepared GO powder, a BYK organic silicon defoaming agent and a BYK flatting agent into KH566 modified water-based acrylic emulsion, and stirring at the rotating speed of 900 r/min for 30min to obtain the GO/KH566 modified water-based acrylic coating, wherein the weight percentages of the raw materials are as follows:

94.8 percent of KH566 modified acrylic emulsion,

GO 5%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 4

1) Preparation of CH @ GO: in the same manner as in the example 1,

2) preparation of GC @ GO: in the same manner as in the example 1,

3) preparation of KH566 modified acrylic emulsion: in the same manner as in the example 1,

4) preparation of water emulsion type acrylic acid composite coating:

introducing prepared GC @ GO powder, a BYK organic silicon defoaming agent and a BYK flatting agent into KH566 modified water-based acrylic emulsion, and stirring at the rotating speed of 900 r/min for 30min to obtain the GC @ GO/KH566 modified water-based acrylic coating, wherein the weight percentages of the raw materials are as follows:

94.8 percent of KH566 modified acrylic emulsion,

GC@GO 5%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 5

1）RGO⁺The preparation of (1): dispersing 0.5g of GO in 250 mL of DMF and carrying out ultrasonic treatment for 1h, then placing the obtained stable solution containing GO in an oil bath at 80 ℃ for heat preservation for 24h, then removing a heat source, cooling the solution to 25 ℃, then washing the solution by using ethanol and deionized water to remove residual solvent, and freeze-drying the product obtained by centrifugal separation to obtain Reduced Graphene Oxide (RGO) powder. Adding the obtained RGO into acetone, ultrasonically dispersing for 30min, slowly adding 1.35g acetic acid under stirring at 28 deg.C, stirring for 3 hr to enrich surface charge to obtain RGO⁺Finally drying for 2 days at room temperature;

3) preparation of water emulsion type acrylic acid composite coating:

introduction of prepared RGO into KH566 modified aqueous acrylic emulsion⁺The powder, BYK organic silicon defoamer and BYK leveling agent are stirred for 30min at the rotating speed of 900 r/min to obtain RGO⁺KH566 modified water-based acrylic paint, wherein the weight percentage of each raw material is as follows:

94.8 percent of KH566 modified acrylic emulsion,

RGO⁺ 5%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Comparative example 6

1) Preparation of RGO: with reference to comparative example 5,

3) preparation of water emulsion type acrylic acid composite coating:

introducing prepared RGO powder, a BYK organic silicon defoaming agent and a BYK flatting agent into KH566 modified water-based acrylic emulsion, and stirring at the rotating speed of 900 r/min for 30min to obtain the RGO/KH566 modified water-based acrylic coating, wherein the weight percentage of each raw material is as follows:

94.8 percent of KH566 modified acrylic emulsion,

RGO 5%，

0.1 percent of defoaming agent,

0.1 percent of flatting agent.

Performance testing

The paints obtained in examples 1 to 5 and comparative examples 1 to 3 and 6 were applied to CRFT panels, and the results of inspecting the paint films are shown in tables 1 to 2. Wherein, the chemical reagent resistance of the paint film is expressed by the phenomenon of change of the surface of the paint film after the paint film reaches the specified test time by measuring the acid and alkali resistance of the paint film according to the national standard GB/T1763-79 (89) < method for measuring chemical reagent resistance of the paint film >. The paint films were subjected to a neutral salt spray resistance test according to the national standard GB/T1771-2007. The pencil hardness of the paint film is tested according to GB/T6739-2006. The paint film adhesion was tested according to GB 9286-1998.

TABLE 1 mechanical testing of the paint films obtained in the examples and comparative examples

As can be seen from Table 1, after addition of GC @ RGO⁺After that, the pencil hardness of the paint film is improved and can reach 5H at most, and simultaneously the prepared water-based acrylic emulsion has high adhesive force, GC @ RGO⁺The adhesion is not affected by the addition of (2). On one hand, due to the existence of amino groups on the chitosan, the polarity of an acrylic acid matrix can be increased, and the adhesive force of the modified coating to the surface of the base material is improved; on the other hand, due to the excellent mechanical properties of the graphene nanosheets, the composite coating has high hardnessThe acrylic emulsion modified by KH566 has high crosslinking density and paint film hardness. However, when the content of the reinforcing agent is too high, agglomeration occurs, so that the properties are deteriorated. As can be seen from comparison of comparative example 3 with comparative example 6, the increase in pencil hardness of the paint film is greater with RGO as the reinforcing agent. However, RGO has poor dispersibility in emulsion, and when added in an excessive amount, agglomeration occurs, which results in small projections on the surface of the paint film and a decrease in the adhesion of the paint film.

TABLE 2 Corrosion resistance testing of the paint films obtained in the examples and comparative examples

As can be seen from the data in Table 2, the corrosion resistance of the purely aqueous acrylic coating is poor, the paint film has blistered and loses gloss less than 24 hours in the salt spray test, and GC @ RGO is added⁺After that, the corrosion resistance of the paint film is obviously improved and is increased along with GC @ RGO⁺The content is gradually increased when GC @ RGO⁺At a content of 4%, the paint film exhibits excellent corrosion resistance. This is due to RGO as a plane enhancer⁺The nano sheet has a two-dimensional structure, so that a water permeation path can be effectively blocked, but graphene is easy to agglomerate, and the performance of the nano sheet is influenced by too much using amount. And it can be seen from the comparison of comparative example 3 with comparative example 6 that the anticorrosive property of GO is slightly inferior to RGO because of more surface defects.

The antibacterial performance test of the paint films obtained in examples 1-5 and comparative examples 4-6 adopts homemade fluorescent escherichia coli, the light emitting values in 5min, 30min and 60min culture are observed, and the bacteriostasis rate is calculated, and the results are shown in table 3.

TABLE 3 antibacterial property test of paint films obtained in examples and comparative examples

As shown in Table 3, the antibacterial performance of each example was improved, particularly example 4The antibacterial agent shows the best antibacterial performance, the bacteria are inactivated at 5min, and 99.87% of the bacteria die after 60 min. At the same time, as can be seen from the table, RGO alone⁺Also has antibacterial property, the antibacterial rate is 91.65% after 60min, and RGO has no antibacterial property, and the antibacterial principle is proved to be RGO⁺The positive charge on the surface forms hydrogen bonds and electrostatic attraction with bacteria, so that cells cannot take up important nutrients and die immediately.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. The multifunctional water-based paint for the inner wall plate of the refrigerated container is characterized by comprising the following components in percentage by weight:

94 to 99 percent of KH566 modified acrylic emulsion,

1 to 5 percent of antibacterial reinforcing agent,

0.1 to 0.5 percent of flatting agent,

0.1 to 0.5 percent of defoaming agent,

the sum of the weight percentages of the components is 100 percent;

wherein the antibacterial reinforcing agent is cationic reduced graphene oxide GC @ RGO with chitosan quaternary ammonium salt grafted on the surface⁺；

The preparation steps of the antibacterial reinforcing agent are as follows:

1) preparation of CH @ GO: weighing 0.2g of GO, adding into 100mL of deionized water, ultrasonically dispersing for 1h, then adding 1mL of acetic acid, mixing uniformly, slowly adding 1g of chitosan under a magnetic stirring state, reacting for 5h at 25 ℃, filtering and washing the obtained product until the pH is =7, taking out a filter cake, and freeze-drying to obtain graphene oxide grafted chitosan CH @ GO;

2) preparation of GC @ GO: uniformly dispersing 0.1g of CH @ GO prepared in the step 1) into 30mL of deionized water, adjusting the pH value to 9 by using 0.16mol/L NaOH solution, adding 20mL of epoxypropyltrimethylammonium chloride solution with the concentration of 100mg/mL, heating in a water bath to 60 ℃, reacting for 2h, standing for 24h, repeatedly cleaning a sample, and drying at 60 ℃ to prepare GC @ GO;

3）GC@RGO⁺the preparation of (1): dispersing 0.1g of GC @ GO prepared in the step 2) in 100mL of DMF, carrying out ultrasonic treatment for 1h, then placing the mixture in an oil bath at the temperature of 80 ℃ for heat preservation reaction for 24h, then cooling to 25 ℃, washing with ethanol and deionized water, carrying out centrifugal separation to obtain a product, and freeze-drying to obtain GC @ RGO powder; adding the obtained GC @ RGO into acetone, ultrasonically dispersing for 30min, then slowly adding 1.35g of acetic acid into the acetone under stirring at the temperature of 28 ℃, and stirring for 3 h to obtain GC @ RGO⁺Drying at room temperature for 2 days;

the preparation steps of the KH566 modified acrylic emulsion are as follows:

step 1, preparing 80g of deionized water, 0.24g of a compound emulsifier prepared from sodium dodecyl diphenyl ether disulfonate and 0.24g of alkylphenol polyoxyethylene, and 0.4g of NaHCO₃A buffering agent, stirring and mixing at 250 r/min, slowly dripping seed monomers of 24g MMA and 8g BA at the same time, and keeping the temperature at 30 ℃ for 1h to obtain seed emulsion serving as a nuclear layer; adding 8g of main monomer MMA, 16g of BA, 4g of functional monomer AA and 4g of HPMA into 20g of deionized water, 0.36g of sodium dodecyl diphenyl ether disulfonate and 0.36g of alkylphenol polyoxyethylene ether as emulsifier, and stirring for 1 hour at the temperature of 30 ℃ to prepare pre-emulsion serving as a shell layer;

step 2, weighing 0.4g of KPS, dissolving in 20g of deionized water to obtain an initiator solution, heating to 65 ℃, adding 1/3 of the initiator solution into the seed emulsion serving as the core layer, reacting for 0.5h to obtain a blue-emitting seed emulsion, keeping the temperature, reacting for 0.5h, beginning to dropwise add the pre-emulsion serving as the shell layer and the rest of the initiator, controlling the dropwise adding time within 1-2 h, heating to 75 ℃ after the dropwise adding is finished, reacting for 4h, cooling to room temperature after the reaction is completed, adjusting the pH value to 7-7.5, and discharging to obtain an acrylic emulsion;

and 3, pouring the KH566 coupling agent into 90vol% ethanol solution, adjusting the pH to 3-4 with phosphoric acid, stirring and hydrolyzing at room temperature for 1h, then pouring into the prepared acrylic emulsion, and stirring at high speed for 1h to obtain the KH566 modified acrylic emulsion.

2. The multifunctional water-based paint for the inner wall panels of the refrigerated container as claimed in claim 1, wherein the amount of the KH566 coupling agent used in step 3 is 5-10wt% of the amount of the acrylic emulsion, and the mass ratio of KH566 to the ethanol solution used is 1: 4.

3. The multifunctional water-based paint for the inner wall panel of the refrigerated container as claimed in claim 1, wherein: the defoaming agent is specifically a BYK organic silicon defoaming agent.

4. The multifunctional water-based paint for the inner wall panel of the refrigerated container as claimed in claim 1, wherein: the leveling agent is specifically a BYK leveling agent.